WO2018179848A1 - Ink set and image forming method - Google Patents

Ink set and image forming method Download PDF

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Publication number
WO2018179848A1
WO2018179848A1 PCT/JP2018/003872 JP2018003872W WO2018179848A1 WO 2018179848 A1 WO2018179848 A1 WO 2018179848A1 JP 2018003872 W JP2018003872 W JP 2018003872W WO 2018179848 A1 WO2018179848 A1 WO 2018179848A1
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Prior art keywords
group
water
resin
acid
formula
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PCT/JP2018/003872
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French (fr)
Japanese (ja)
Inventor
大島　康仁
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富士フイルム株式会社
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Publication of WO2018179848A1 publication Critical patent/WO2018179848A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/30—Inkjet printing inks
    • C09D11/40—Ink-sets specially adapted for multi-colour inkjet printing
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/54—Inks based on two liquids, one liquid being the ink, the other liquid being a reaction solution, a fixer or a treatment solution for the ink

Definitions

  • the present disclosure relates to an ink set and an image forming method.
  • the recording method using the ink jet method is widely used because a high-quality image can be recorded on a wide variety of substrates by ejecting ink in droplets from a number of nozzles provided in the ink jet head. It's being used.
  • Various forms of image forming methods using the inkjet method have been proposed. For example, an ink set using an ink containing a colorant and a pretreatment liquid containing a compound that aggregates the components in the ink is used. The method to use is known. In this method, for example, an image with excellent resolution can be formed by bringing the ink and the pretreatment liquid into contact with each other.
  • an overcoat liquid containing water-dispersible polyurethane, two kinds of specific compounds, and water is applied to the surface of the recording medium on which the inkjet ink is ejected (for example, Japanese Patent Application Laid-Open No. 2015-2015). No. 172124).
  • the resin contained in the clear ink printed on the image contains acrylic acid having a carboxy group. Components such as resin particles in the clear ink tend to aggregate due to the acid therein, and as a result, a high gloss image cannot be obtained.
  • an aqueous treatment liquid film is formed on an image recorded with pigment ink. The same liquid is used, and the flocculant contained in the aqueous treatment liquid is a polyvalent metal salt. Since the polyvalent metal salt has a weak cohesive force with respect to components such as resin particles in the ink as compared with the acid, the problem of reducing the glossiness of the image hardly occurs, but the sharpness of the image becomes insufficient.
  • overcoat liquids many commercial products marketed as overcoat liquids (so-called aqueous varnishes) have components such as resin particles dispersed and stabilized with carboxylic acid. Therefore, when an image is formed by utilizing the action of an acid contained as a flocculant in the pretreatment liquid, it is dispersed in the overcoat liquid by the action of the acid, as in the case of pigments dispersed and contained in the ink. Aggregation of components such as resin particles tends to occur. When aggregation occurs in the overcoat liquid, the overcoat liquid thickens. Thereby, when the overcoat liquid is applied, irregularities are generated on the surface of the coating film, and the gloss of the film is lowered.
  • the overcoat liquid described in JP-A-2015-172124 is also a resin particle having a carboxy group as a dispersion stabilizing group, as is apparent from the content of Japanese Patent No. 366047 described as a specific example of the production method (see FIG. That is, it is considered that a highly glossy film cannot be obtained due to the increase in viscosity due to aggregation of the resin particles.
  • Such a decrease in the glossiness of the film is a phenomenon that tends to occur in a non-curing aqueous overcoat liquid (so-called aqueous varnish). From the viewpoint of environmental suitability and safety in recent years, it is expected that a water-based overcoat solution that does not easily cause a thickening phenomenon due to aggregation is required.
  • the storage stability of the overcoat liquid is good, and the gloss is good when the image forming surface of the recording material on which an image is formed is overcoated using an acidic pretreatment liquid.
  • the present invention relates to providing an ink set capable of obtaining the characteristics.
  • Another embodiment of the present invention relates to providing an image forming method capable of obtaining good glossiness.
  • Means for solving the above problems include the following aspects. ⁇ 1> An ink composition containing a colorant and water, a pretreatment liquid containing an acid and water, and a resin particle having a group represented by the following formula (1) and having no carboxy group And an overcoat liquid containing water.
  • A represents an alkylene group having 2 or 3 carbon atoms
  • R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms
  • m represents an integer of 3 to 40.
  • the ink set according to ⁇ 1> wherein the total content of the group represented by the formula (1) in the resin contained in the particles is 0.05 g or more and 0.50 g or less per 1 g of the resin.
  • the resin contained in the particles is at least one selected from the group consisting of at least one structural unit represented by the following formula (2), the following formula (3), and the following formula (4).
  • A represents an alkylene group having 2 or 3 carbon atoms
  • R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms
  • R 1 represents a hydrogen atom or a methyl group
  • m represents an integer of 3 to 40.
  • R 2 represents a hydrogen atom or a methyl group
  • R 3 represents a hydrocarbon group having 1 to 20 carbon atoms.
  • ⁇ 4> The ink set according to ⁇ 3>, wherein m in the formula (2) represents an integer of 6 or more and 20 or less.
  • ⁇ 5> The ink set according to any one of ⁇ 1> to ⁇ 4>, wherein the particles include a nonionic surfactant having a group represented by the formula (1).
  • ⁇ 6> Forming an image by applying a pretreatment liquid containing acid and water to the recording material, and applying an ink composition containing a colorant and water to the application surface of the pretreatment liquid of the recording material And a resin particle having a group represented by the formula (1) and not having a carboxy group on at least a part of the recording material on which an image is formed, and over containing water. Applying the coating liquid.
  • the storage stability of the overcoat solution is good, and the image forming surface of the recording material on which an image is formed using an acidic pretreatment solution is good.
  • an ink set capable of obtaining high glossiness.
  • an image forming method capable of obtaining good glossiness is provided.
  • a numerical range indicated by using “to” means a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
  • an upper limit value or a lower limit value described in a numerical range may be replaced with an upper limit value or a lower limit value in another numerical range.
  • the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.
  • a combination of two or more preferred embodiments is a more preferred embodiment.
  • the content of each component means the total content of the plurality of types of substances unless there is a specific notice when there are a plurality of types of substances corresponding to the respective components.
  • process is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes.
  • (meth) acryl is a term used in a concept including both acrylic and methacrylic.
  • An ink set of the present disclosure includes an ink composition containing a colorant and water, a pretreatment liquid containing an acid and water, a resin having a group represented by the formula (1) and having no carboxy group And an overcoat liquid containing water.
  • the ink set of the present disclosure has good storage stability of the overcoat liquid, and good gloss when the image forming surface of a recording material on which an image is formed is overcoated using an acidic pretreatment liquid Is obtained.
  • JP-A-2015-199780 and JP-A-2003-326829 disclose a technique for improving image abrasion or water resistance by providing a liquid containing resin particles dispersed on an image. ing.
  • a pretreatment liquid containing an aggregating agent for aggregating the pigment in the ink composition in addition to the ink composition containing the pigment or the like, it is brought into contact with the pretreatment liquid.
  • the ink composition After the ink composition is ejected and an image is formed, when the image is overcoated with a liquid containing components such as resin particles, the components in the overcoated liquid aggregate and thicken.
  • the effect of improving gloss may be reduced.
  • the aggregating agent contained in the aqueous treatment liquid is a polyvalent metal salt
  • the polyvalent metal salt has a weaker aggregating action of the dispersed component than the acid. It is expected that the viscosity increase due to the aggregation of the components in the liquid when the image is overcoated is small.
  • the overcoat liquid described in JP-A-2015-172124 also contains resin particles having a carboxy group as a dispersion stabilizing group (that is, water-dispersible polyurethane particles), and therefore, due to aggregation of the resin particles. It is thought that thickening occurs and a highly glossy film cannot be obtained. In general, in an overcoat liquid in which resin particles and the like are dispersed and contained, good storage stability is required.
  • an image formed using an acid-containing treatment liquid in an aqueous pretreatment liquid containing an acid (hereinafter also referred to as “acid-containing treatment liquid”) and an ink composition.
  • an aqueous overcoat solution containing resin particles having a specific group that is, a group represented by the formula (1)
  • the overcoat solution Even when the image forming surface of a recording material on which an image is formed is overcoated using the containing treatment liquid, good glossiness can be obtained.
  • the ink set of the present disclosure even when an image formed using an acid-containing processing liquid is overcoated, thickening due to aggregation of components in the overcoat liquid due to the action of an acid in the acid-containing processing liquid can be suppressed. Therefore, the occurrence of irregularities such as streaks that cause a decrease in gloss is effectively suppressed. As a result, it is considered that the effect of improving the glossiness of the image by performing the overcoat treatment is excellent.
  • the resin forming the resin particles contained in the overcoat liquid has a specific group (that is, a group represented by the formula (1)) and does not have a carboxy group, The overcoat solution has good storage stability.
  • the overcoat liquid will be described first, and then the ink composition and the pretreatment liquid will be described.
  • the overcoat liquid contains particles of a resin having a group represented by the formula (1) and not having a carboxy group, and water.
  • the overcoat liquid is an aqueous liquid.
  • the overcoat liquid contains a resin particle having a group represented by the formula (1) and not having a carboxy group, the storage stability is improved.
  • the overcoat liquid has an image forming surface formed by using a pretreatment liquid containing an acid by containing particles of a resin having a group represented by the formula (1) and not having a carboxy group. Even when the film is overcoated, good gloss can be obtained.
  • the overcoat liquid contains resin particles having a group represented by the formula (1) and not having a carboxy group.
  • the resin forming the particles is not particularly limited as long as it has a group represented by the formula (1) and does not have a carboxy group and can maintain the shape of the particles in an aqueous liquid.
  • the resin can be appropriately selected from known resins, and is preferably a water-insoluble or poorly water-soluble resin (hereinafter, the resin forming the particles is also referred to as “water-insoluble resin”).
  • water-insoluble or poorly water-soluble means that when the resin is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., the dissolved amount is 15 g or less. That means.
  • the dissolution amount is the dissolution amount when 100% neutralized with sodium hydroxide or acetic acid according to the type of the salt-forming group of the water-insoluble or poorly water-soluble resin.
  • A represents an alkylene group having 2 or 3 carbon atoms
  • R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms
  • m represents an integer of 3 to 40.
  • the water-insoluble resin may have only one type represented by the formula (1), or may have two or more types.
  • a in Formula (1) represents an alkylene group having 2 or 3 carbon atoms. Specific examples of the alkylene group having 2 or 3 carbon atoms include —CH 2 CH 2 —, —CH 2 CH 2 CH 2 —, and —CH (CH 3 ) CH 2 —. From the viewpoint that the storage stability of the overcoat solution is better, A is preferably —CH 2 CH 2 —.
  • the alkylene group having 2 or 3 carbon atoms represented by A may be only one kind in the formula (1), or may be contained in two or more kinds.
  • m represents the total sum of repeating units represented by — (AO) — contained in two or more types.
  • AO repeating units represented by —
  • R in the formula (1) represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.
  • the hydrocarbon group having 1 to 20 carbon atoms include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms (methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, Octyl group, nonyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, 2-cyclohexylethyl group, norbornyl group, adamantyl group, etc.), aryl group having 6 to 20 carbon atoms (phenyl group, naphthyl group, 4-biphenyl) Group, 2-biphenyl group, etc.), and aralkyl groups having 7 to 20 carbon atoms (benzyl group, phenethyl group, 3-phenylpropyl
  • the hydrocarbon group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms, It is more preferably an alkyl group of 1 to 4, more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.
  • hydrocarbon groups may have a substituent.
  • Substituents include halogen atoms (chlorine atoms, fluorine atoms, bromine atoms, etc.), hydroxy groups, thiol groups, sulfo groups, cyano groups, epoxy groups, —OR 10 groups, —OCOR 10 groups, —COOR 10 groups, — COR 10 group, —N (R 10 ) (R 11 ) group, —NHCONHR 10 group, —NHCOOR 10 group, —Si (R 10 ) 3 group, —CONHR 10 group and the like can be mentioned. A plurality of these substituents may be substituted in the alkyl group.
  • R 10 and R 11 are each independently methyl, ethyl, propyl, butyl, heptyl, hexyl, octyl, decyl, propenyl, butenyl, hexenyl, octenyl, 2-hydroxy Ethyl group, 3-chloropropyl group, 2-cyanoethyl group, N, N-dimethylaminoethyl group, 2-bromoethyl group, 2- (2-methoxyethyl) oxyethyl group, 2-methoxycarbonylethyl group, 3-carboxyethyl Group, 3-carboxypropyl group, benzyl group and the like. Note that when the hydrocarbon group having 1 to 20 carbon atoms has a substituent, the number of carbon atoms represents the total including the number of carbon atoms contained in the substituent.
  • M in Formula (1) represents an integer of 3 to 40. Preferably it represents an integer of 5 or more and 25 or less, more preferably an integer of 6 or more and 20 or less.
  • m is in the above range, the storage stability of the overcoat liquid is good, and the water resistance of the film formed from the overcoat liquid is good.
  • the total content of the group represented by the formula (1) in the water-insoluble resin contained in the particles is preferably 0.05 g or more and 0.50 g or less, and 0.10 g or more and 0 or less per 1 g of the water-insoluble resin. More preferably, it is not more than .40 g, more preferably not less than 0.20 g and not more than 0.30 g.
  • the total content of the group represented by the formula (1) in the water-insoluble resin is 0.05 g or more per 1 g of the water-insoluble resin, the storage stability of the overcoat liquid becomes better.
  • the total content of the group represented by the formula (1) in the water-insoluble resin is 0.50 g or less per 1 g of the water-insoluble resin, the water resistance of the film formed by the overcoat liquid becomes good.
  • the water-insoluble resin contained in the particles is a polymer having at least a structural unit derived from a monomer having a group represented by the formula (1) and not having a carboxy group.
  • the water-insoluble resin may contain only one type of structural unit derived from a monomer having a group represented by the formula (1) and not having a carboxy group, or may contain two or more types. May be.
  • the content of the structural unit having the group represented by the formula (1) in the water-insoluble resin contained in the particles is appropriately selected depending on the structure of the structural unit, but is 0.05 g or more per 1 g of the water-insoluble resin. 0.55 g or less is preferable, 0.10 g or more and 0.45 g or less is more preferable, and 0.20 g or more and 0.35 g or less is still more preferable.
  • the content of the structural unit having the group represented by the formula (1) in the water-insoluble resin is 0.05 g or more per 1 g of the water-insoluble resin, the storage stability of the overcoat liquid becomes better.
  • the content of the structural unit having the group represented by formula (1) in the water-insoluble resin is 0.55 g or less per 1 g of the water-insoluble resin, the water resistance of the film formed by the overcoat liquid is good. It becomes.
  • the water-insoluble resin contained in the particles is at least one selected from the group consisting of at least one structural unit represented by the following formula (2), the following formula (3), and the following formula (4). And a structural unit. According to such an aspect, the abrasion resistance and water resistance of the film formed from the overcoat liquid, and the storage stability of the overcoat liquid are further improved.
  • A represents an alkylene group having 2 or 3 carbon atoms
  • R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms
  • R 1 represents a hydrogen atom or a methyl group
  • m represents an integer of 3 to 40.
  • a in Formula (2) is synonymous with A in Formula (1).
  • R in Formula (2) has the same meaning as R in Formula (1).
  • R 1 in formula (2) is preferably a methyl group.
  • M in the formula (2) has the same meaning as m in the formula (1).
  • the water-insoluble resin may contain only one type of structural unit represented by the formula (2), or may contain two or more types.
  • R 2 represents a hydrogen atom or a methyl group
  • R 3 represents a hydrocarbon group having 1 to 20 carbon atoms.
  • R 2 in Formula (3) is preferably a methyl group.
  • R 3 in the formula (3) represents a hydrocarbon group having 1 to 20 carbon atoms and is synonymous with the hydrocarbon group having 1 to 20 carbon atoms represented by R in the formula (1).
  • the water-insoluble resin may include only one type of the structural unit represented by the formula (3), or may include two or more types.
  • the water-insoluble resin contains at least one structural unit represented by the formula (2) and at least one structural unit represented by the formula (4).
  • the water-insoluble resin comprises at least one structural unit represented by the formula (2), at least one structural unit represented by the formula (3), and the formula (4).
  • at least one structural unit represented by: Formula (4) is a structural unit derived from styrene.
  • the water-insoluble resin is at least one structural unit represented by the formula (2), at least one structural unit represented by the formula (3), and at least one structural unit represented by the formula (4). And a structural unit represented by the formula (2), a structural unit represented by the formula (3), and a structural unit represented by the formula (4) in the water-insoluble resin.
  • the content ratio (content of structural unit represented by formula (2) / content of structural unit represented by formula (3) / content of structural unit represented by formula (4)) is based on mass. It is preferably 5 to 55/5 to 75/20 to 80, more preferably 10 to 45/10 to 60/25 to 70, and more preferably 20 to 35/15 to 45/30 to 60. Is more preferable.
  • the content of the structural unit represented by the formula (2) in the water-insoluble resin contained in the particles is preferably 0.05 g or more and 0.55 g or less, and 0.10 g or more and 0.45 g or less per 1 g of the water-insoluble resin. Is more preferable, and 0.20 g or more and 0.35 g or less is still more preferable.
  • the content of the structural unit represented by the formula (2) in the water-insoluble resin is 0.05 g or more per 1 g of the water-insoluble resin, the storage stability of the overcoat liquid becomes better.
  • the content of the structural unit represented by the formula (2) in the water-insoluble resin is 0.55 g or less per 1 g of the water-insoluble resin, the water resistance of the film formed by the overcoat liquid becomes better. .
  • the content of the structural unit represented by the formula (3) in the water-insoluble resin contained in the particles is arbitrary depending on the structure of R 3. However, it is preferably 0.05 g or more and 0.75 g or less, more preferably 0.10 g or more and 0.60 g or less, and still more preferably 0.15 g or more and 0.45 g or less per 1 g of water-insoluble resin.
  • the content of the structural unit represented by the formula (3) in the water-insoluble resin contained in the particles is within the above range, the water resistance of the film formed by the overcoat liquid becomes better.
  • the content of the structural unit represented by the formula (4) in the water-insoluble resin contained in the particles is 0 per 1 g of the water-insoluble resin. 20 g or more and 0.80 g or less is preferable, 0.25 g or more and 0.70 g or less is more preferable, and 0.30 g or more and 0.60 g or less is still more preferable.
  • the content of the structural unit represented by the formula (4) in the water-insoluble resin contained in the particles is within the above range, the gloss of the film formed by the overcoat liquid becomes better.
  • the content of the group represented by the formula (1) contained in the resin in the water-insoluble resin, the structural unit represented by the formula (2), the structural unit represented by the formula (3), and the formula ( The content of the structural unit represented by 4) is determined by the following method.
  • the overcoat solution is centrifuged using a test tube (product name: Amicon Ultra-15, molecular weight cut off 100 kDa, Merck) equipped with an ultrafiltration filter, and the water-insoluble resin particles are collected and completely dissolved in the solvent. Then, the structure is identified by nuclear magnetic resonance spectroscopy (NMR method). Based on the obtained results, the content of the group represented by the formula (1) contained in the resin, the structural unit represented by the formula (2), the structural unit represented by the formula (3), and the formula The content of the structural unit represented by (4) is calculated.
  • the water-insoluble resin contained in the particles may contain a constituent unit derived from another monomer other than the constituent units described above.
  • the structural unit derived from other monomers is not particularly limited, and examples thereof include ⁇ -methylstyrene, amide monomers (acrylamide, N- (2-hydroxyethyl) acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, isopropylacrylamide, N- (2-hydroxymethyl) acrylamide, methacrylamide, etc.), vinyl cyanide monomers (acrylonitrile, methacrylonitrile, etc.), ethylenically unsaturated carboxylic acid hydroxyalkyl esters Monomers ( ⁇ -hydroxyethyl acrylate, ⁇ -hydroxyethyl methacrylate, etc.), dialkylaminoalkyl (meth) acrylamide hydrochlorides and tertiary salts such as sulfates (dimethylaminoethyl (meth) acryl
  • the water-insoluble resin contained in the particles does not have a carboxy group. If the water-insoluble resin contained in the particles has a carboxy group, the acid, which is an aggregating component contained in the pretreatment liquid described later, reacts with the water-insoluble resin to aggregate the particles, resulting in a decrease in gloss. Invite.
  • the water-insoluble resin contained in the particles does not have a carboxy group, so that the gloss of the formed film is good.
  • “having no carboxy group” means that the water-insoluble resin has substantially no carboxy group.
  • substantially does not have means that even when it has a carboxy group, it exhibits the same performance as when it does not.
  • the content of the carboxy group in the water-insoluble resin is, for example, 0.05 g or less, preferably 0. 03 g or less, more preferably 0.01 g or less.
  • the glass transition temperature (Tg) of the water-insoluble resin is preferably 40 ° C. or higher.
  • Tg is preferably 45 ° C. or higher and 150 ° C. or lower, more preferably 50 ° C. or higher and 130 ° C. or lower, from the viewpoint that the heat resistance of the resin film to be formed is well maintained and the film can be satisfactorily formed. It is preferably 55 ° C. or higher and 110 ° C. or lower.
  • the Tg of the water-insoluble resin is a value measured by a differential scanning calorimetry (DSC).
  • DSC differential scanning calorimeter
  • EXSTAR 6220 manufactured by SII Nanotechnology Inc. can be used.
  • the weight average molecular weight (Mw) of the water-insoluble resin is preferably 1,000 to 1,000,000, more preferably 5,000 to 500,000, still more preferably 10,000 to 300,000, From the viewpoint of viscosity, 20,000 to 70,000 is particularly preferable.
  • the weight average molecular weight of the water-insoluble resin is a value measured by gel permeation chromatography (GPC).
  • GPC uses HLC-8220GPC (Tosoh Corp.) as a measuring device, and three columns of TSKgel, Super Multipore HZ-H (4.6 mm ID ⁇ 15 cm, Tosoh Corp.) as columns.
  • eluent THF tetrahydrofuran
  • RI refractometer
  • the calibration curve is “standard sample TSK standard, polystyrene” of Tosoh Corporation: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000” Prepared from 8 samples of “A-2500”, “A-1000”, and “n-propylbenzene”.
  • the particle of the water-insoluble resin contains a nonionic surfactant having a group represented by the formula (1), that is, a nonion having a group represented by the formula (1) on at least a part of the surface of the particle. It is preferable to have a surfactant.
  • the particles include at least a particulate water-insoluble resin and a nonionic surfactant having a group represented by the formula (1).
  • “including a nonionic surfactant having a group represented by the formula (1)” covers the surface of the water-insoluble resin with the nonionic surfactant having a group represented by the formula (1).
  • a mode in which a nonionic surfactant having a group represented by the formula (1) is contained in the water-insoluble resin.
  • nonionic surfactant having a group represented by the formula (1) a nonionic surfactant having a group represented by the formula (1) introduced into the liquid is described later.
  • the particles and the nonionic surfactant having the group represented by the formula (1) are taken out from another phase, or the particles and the formula ( This is determined by whether the nonionic surfactant having the group represented by 1) is simultaneously taken out from the same phase.
  • nonionic surfactant any conventionally known surfactant can be used without limitation as long as it has at least the group represented by the formula (1).
  • examples of the nonionic surfactant having a group represented by the formula (1) include compounds having a combination of a hydrophobic group and ethylene oxide and / or propylene oxide in the molecule. Specifically, alkyl (carbon number: 6 to 40) phenol-ethylene oxide condensate, aliphatic (carbon number: 6 to 40) first or second linear or branched alcohol and condensation product of ethylene oxide And those represented by the structure of R—O— (CH 2 CH 2 O) n—H (R and n are the same as R and n in formula (1)) are preferable.
  • nonionic surfactant having a group represented by the formula (1) commercially available products can be used.
  • examples of commercially available nonionic surfactants having a group represented by the formula (1) include Kao's Emulgen (registered trademark) series, Nippon Emulsifier's New Coal (registered trademark) series, Neugen (registered trademark) series of Daiichi Kogyo Seiyaku Co., Ltd., Adekator (registered trademark) series of ADEKA Corporation, New Pole (registered trademark) series, Sanyo Chemical Co., Ltd.
  • the total content of the group represented by the formula (1) in the nonionic surfactant contained in the particles is preferably 0.05 g or more and 0.50 g or less per 1 g of the water-insoluble resin forming the particles. 0.10 g or more and 0.40 g or less, more preferably 0.20 g or more and 0.30 g or less.
  • the total content of the group represented by the formula (1) in the nonionic surfactant is 0.05 g or more per 1 g of the water-insoluble resin forming the particles, the storage stability of the overcoat liquid is better. It becomes.
  • the total content of the group represented by the formula (1) in the nonionic surfactant is 0.50 g or less per 1 g of the water-insoluble resin, the water resistance of the film formed by the overcoat liquid is good. Become.
  • the content of the group represented by the formula (1) in the nonionic surfactant contained in the particles is determined by the following method.
  • the overcoat solution is centrifuged using a test tube (product name: Amicon Ultra-15, molecular weight cut off 100 kDa, Merck) equipped with an ultrafiltration filter, and the water-insoluble resin particles are collected and completely dissolved in the solvent. Then, the structure is identified by nuclear magnetic resonance spectroscopy (NMR method). Based on the obtained results, the content of the group represented by the formula (1) in the nonionic surfactant contained in the particles is calculated.
  • the water-insoluble resin particles may be used in the form of a dispersion in which the particles are dispersed in an aqueous medium (so-called aqueous dispersion called latex).
  • a dispersion in which water-insoluble resin particles are dispersed in an aqueous medium can be prepared by a conventionally known method. Examples of the production method include Method A and Method B shown below.
  • Method A A hydrophobic polymer is dissolved in a water-miscible organic solvent (acetone, methanol, etc.), and then added to water containing a nonionic surfactant having a group represented by the formula (1). The mixture is stirred to obtain an emulsified state. Next, the aqueous dispersion of water-insoluble resin particles dispersed with a nonionic surfactant having a group represented by the formula (1) is obtained by heating and / or reducing pressure and distilling off the organic solvent.
  • Method to obtain (so-called phase inversion emulsification method).
  • Method B A hydrophobic polymerizable monomer and a thermal polymerization initiator are added to water containing a nonionic surfactant having a group represented by the formula (1), and stirred to obtain an emulsified state. Next, polymerization is initiated in micelles by heat to obtain an aqueous dispersion of water-insoluble resin particles (so-called emulsion polymerization method).
  • the aqueous dispersion of water-insoluble resin particles is preferably prepared by Method B from the viewpoint of the abrasion resistance and water resistance of the film formed by the overcoat liquid and the storage stability of the overcoat liquid.
  • the average particle size of the water-insoluble resin particles is preferably 10 nm to 500 nm, more preferably 20 nm to 400 nm, and still more preferably 30 nm to 300 nm in terms of volume average particle size.
  • the particle size distribution of the water-insoluble resin particles is not particularly limited, and may be either a wide particle size distribution or a monodisperse particle size distribution. Further, two or more kinds of water-insoluble resin particles having a monodisperse particle size distribution may be mixed and used.
  • the average particle size and particle size distribution of the water-insoluble resin particles are determined by measuring the volume average particle size by a dynamic light scattering method using a nanotrack particle size distribution measuring device.
  • a nanotrack particle size distribution measuring apparatus for example, UPA-EX150 manufactured by Nikkiso Co., Ltd. can be used.
  • the overcoat liquid may contain only one kind of water-insoluble resin particles, or may contain two or more kinds.
  • the content of the resin particles in the overcoat liquid is not particularly limited, and is preferably 10% by mass to 50% by mass, more preferably 15% by mass to 45% by mass with respect to the total mass of the overcoat liquid, 20 More preferred is from 40% by weight.
  • the content of the resin particles in the overcoat liquid is 10% by mass or more, the gloss of the film formed by the overcoat liquid becomes better.
  • the content of the resin particles in the overcoat liquid is 50% by mass or less, the storage stability of the overcoat liquid becomes better.
  • the overcoat liquid contains water.
  • the overcoat liquid is an aqueous liquid containing water as a main solvent.
  • water is the main solvent” means that the content of water exceeds 50% by mass with respect to the total mass of all solvents contained in the overcoat solution.
  • the content of water in the overcoat liquid is not particularly limited, and is preferably 20% by mass to 80% by mass, and more preferably 30% by mass to 70% by mass with respect to the total mass of the overcoat liquid.
  • the overcoat liquid may contain components other than the above components.
  • examples of other components include organic solvents, surfactants, and waxes.
  • bead particles that are incompatible with the resin particles described above may be included.
  • Organic solvent- Organic solvents include alcohol (methanol, ethanol, propanol, isopropanol (IPA), butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.), polyhydric alcohol (ethylene glycol) , Diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), glycol derivatives (ethylene glycol monomethyl ether, ethylene glycol) Monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Monomethyl ether, diethylene glycol monobutyl ether (butyl carbitol), propylene glycol
  • the overcoat liquid may contain a surfactant.
  • the surfactant include nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants, and the like, and anionic surfactants are preferable.
  • anionic surfactant it can select from a well-known thing suitably, For example, a sulfate ester salt, a sulfonate, a phosphate, a fatty acid salt, a formalin condensate etc. are mentioned.
  • cations that form salts include ammonium ions, triethanolamine ions, metal cations, and the like. Among these, as the cation forming the salt, a monovalent metal cation is preferable, and sodium ion or potassium ion is particularly preferable.
  • the anionic surfactant preferably contains at least one selected from a sulfonate salt and a sulfate ester salt from the viewpoint that the effect of suppressing the decrease in the density of the solid image portion and the effect of suppressing the stripe unevenness are more excellent.
  • anionic surfactants sodium lauryl sulfate, linear sodium dodecylbenzene sulfonate, branched sodium dodecylbenzene sulfonate, or sulfosuccinic acid is preferable because the effect of improving the wettability of the surface of the recording material is easily exhibited. Acid-di-2-ethylhexyl sodium is preferred.
  • the content of the surfactant in the overcoat liquid is such that the surface tension of the overcoat liquid (25 ° C.) is 20 mN from the viewpoint of making the coated film uniform and improving the gloss. It is preferably an amount that can be adjusted to 40 mN / m or less, more preferably an amount that can be adjusted to 25 mN / m to 35 mN / m.
  • the overcoat liquid may contain a wax.
  • wax means a polymer compound having a melting point of 170 ° C. or less
  • wax particles means particles formed from the above wax.
  • the wax is distinguished from “resin” which is a polymer compound having no melting point or a melting point exceeding 170 ° C., and wax particles are distinguished from “resin particles”.
  • fusing point means the temperature of the endothermic peak top in DSC measurement using a differential scanning calorimeter (DSC: Differential scanning calorimetry).
  • DSC differential scanning calorimeter
  • EXSTAR 6220 of Hitachi High-Tech Science Co., Ltd. can be used.
  • the wax is preferably contained in the form of particles from the viewpoint of dispersion stability. That is, the wax is preferably contained in the form of wax particles.
  • the particles may be used in the form of a dispersion in which particles are dispersed in an aqueous medium (so-called aqueous dispersion called latex).
  • waxes examples include plant systems such as carnauba wax, candelix wax, beeswax, rice wax, lanolin, animal waxes, paraffin wax, microcrystalline wax, polyolefin wax (polyethylene wax, oxidized polyethylene wax, etc.), petrolatum, etc.
  • Natural wax or synthetic wax such as petroleum wax, montan wax, mineral wax such as ozokerite, synthetic wax such as carbon wax, Hoechst wax, stearamide, ⁇ -olefin / maleic anhydride copolymer, or a mixture thereof Is mentioned.
  • the wax is preferably at least one selected from carnauba wax and polyolefin wax, and polyethylene wax is particularly preferable from the viewpoint of image scratch resistance.
  • the wax is preferably added in the form of a dispersion, and can be included in the overcoat liquid, for example, as a dispersion such as an emulsion.
  • a solvent in the case of a dispersion water is preferable, but it is not limited to water.
  • a commonly used organic solvent can be appropriately selected and used during dispersion.
  • a commercially available product can be used as the wax.
  • Examples of commercially available waxes include Nopcoat PEM17 (San Nopco), Chemipearl (registered trademark) W4005 (Mitsui Chemicals), AQUACER (registered trademark) 515, AQUACER (registered trademark) 531 and AQUACER (registered trademark) 593. (Above, Big Chemie Japan Co., Ltd.), Cellosol 524 (Chukyo Yushi Co., Ltd.), etc.
  • the overcoat solution contains a wax
  • it may contain only one type of wax or two or more types.
  • the overcoat liquid may contain bead particles.
  • bead particles include particles such as acrylic resin beads, amino resin beads, polyolefin resin beads, alumina beads, and glass beads.
  • acrylic resin beads polymethyl methacrylate, polybutyl methacrylate, polymethacrylate, polystyrene having a refractive index of 1.40 to 1.60 and a true specific gravity of 1.01 to 1.50. And other resins (polymethyl methacrylate, polybutyl methacrylate, polymethacrylates, etc.).
  • Amino resin beads include melamine / formaldehyde condensate, benzoguanamine / formaldehyde condensate, melamine / benzoguanamine / formaldehyde having a refractive index of 1.50 to 1.80 and a true specific gravity of 1.30 to 1.80. Examples include condensates and silica-treated products of these condensates.
  • polyolefin resin beads examples include polyethylene resin beads and polypropylene resin beads having a refractive index of 1.30 to 1.60 and a true specific gravity of 0.90 to 1.80.
  • alumina beads examples include aluminum oxide having a refractive index of 1.50 to 1.90 and a true specific gravity of 3.80 to 4.00.
  • soda-lime glass having a refractive index of 1.40 to 2.30 and a true specific gravity of 2.40 to 4.60
  • titanium-barium glass low alkali glass, low alkali borosilicate Glass etc.
  • the beads to be used are incompatible with resin particles having a group represented by the above-described formula (1) and not having a carboxy group.
  • the overcoat liquid is formed of the overcoat liquid by including bead particles having a group represented by the above-described formula (1) and not compatible with resin particles not having a carboxy group.
  • the gloss of the film can be controlled.
  • the overcoat liquid contains bead particles, it may contain only one kind of bead particles or two or more kinds.
  • the content of the bead particles in the overcoat liquid is a ratio of the resin particle content to the bead particle content (resin particle content / The content of the bead particles) is preferably in the range of 20/1 to 1/3, and more preferably in the range of 2/1 to 1/2.
  • the gloss of the film formed by the overcoat liquid can be controlled to a desired gloss.
  • the adhesion of the film formed by the overcoat liquid tends to be insufficient.
  • the bead particles preferably have a refractive index of 1.4 or more and an average particle diameter of 0.5 ⁇ m to 30 ⁇ m.
  • the refractive index and the average particle diameter of the bead particles are within the above range, the bead particles do not diffuse light and the gloss control becomes easy.
  • the average particle diameter of the bead particles is 0.5 ⁇ m to 30 ⁇ m, the adhesion of the film formed by the overcoat liquid is improved.
  • the pH of the overcoat solution is preferably 5.0 to 10.0, more preferably 6.0 to 9.0, from the viewpoint of storage stability.
  • the pH of the overcoat solution is a value measured using a pH meter in a state where the temperature of the overcoat solution is adjusted to 25 ° C. in an environment of 25 ° C.
  • As the pH meter for example, WM-50EG manufactured by Toa DK Corporation can be used.
  • surface tension of an overcoat liquid there is no restriction
  • the surface tension of the overcoat liquid is a value measured under a condition of 25 ° C. by a plate method using a surface tension meter. As the surface tension meter, for example, Automatic Surface Tensiometer CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. can be used.
  • the surface tension of the overcoat liquid can be adjusted, for example, by adding a surfactant.
  • the ink composition contains a colorant and water, and preferably contains resin particles, and may further contain other components as necessary.
  • the ink composition includes a colorant.
  • the colorant is not particularly limited, and may be a pigment or a dye.
  • the colorant is preferably an anionic colorant, and more preferably a pigment, from the viewpoint of excellent cohesiveness when contacted with an aggregating component (that is, an acid) contained in a pretreatment liquid described later.
  • an aggregating component that is, an acid
  • anionic colorant refers to a carboxy group, a sulfo group, or a phosphate group in the structure (for example, in the structure of a dispersant when the colorant is coated with a dispersant described later).
  • a colorant having an anionic group such as
  • any of an organic pigment or an inorganic pigment may be sufficient.
  • the pigment is preferably insoluble or hardly soluble in water from the viewpoint of ink colorability.
  • Organic pigments include polycyclic pigments such as azo lakes, azo pigments, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, diketopyrrolopyrrole pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments.
  • Dye lakes such as basic dye type lakes and acid dye type lakes; nitro pigments, nitroso pigments, aniline black, daylight fluorescent pigments and the like.
  • inorganic pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black.
  • any pigment that is not described in the color index can be used as long as it is dispersible in water.
  • pigments surface-treated with a surfactant, a polymer dispersant, etc., graft carbon, etc. can also be used.
  • the pigment at least one selected from the group consisting of an azo pigment, a phthalocyanine pigment, an anthraquinone pigment, a quinacridone pigment, and a carbon black pigment is preferable, and an anionic azo pigment, an anionic phthalocyanine pigment, and an anion More preferred is at least one selected from the group consisting of quinacridone pigments.
  • a form in which the pigment is dispersed by a dispersant is preferable.
  • a form in which the pigment is dispersed with the polymer dispersant that is, a form in which at least a part of the pigment is coated with the polymer dispersant is preferable.
  • a pigment at least partially coated with a polymer dispersant is referred to as a “resin-coated pigment”.
  • the dispersant may be a polymer dispersant or a low molecular surfactant type dispersant.
  • the polymer dispersant may be an uncrosslinked polymer dispersant (that is, a non-crosslinked polymer dispersant), or a polymer dispersant that is crosslinked by a crosslinking agent (that is, a crosslinked polymer dispersant). May be.
  • the non-crosslinked polymer dispersant may be a water-soluble non-crosslinked polymer dispersant or a water-insoluble non-crosslinked polymer dispersant.
  • the low molecular surfactant type dispersant the surfactant type dispersants described in paragraphs [0016] to [0020] of JP 2010-188661 A can be used.
  • hydrophilic polymer compounds can be used as the water-soluble non-crosslinked polymer dispersant.
  • water-soluble non-crosslinked polymer dispersant for example, natural hydrophilic polymer compounds described in paragraphs [0021] to [0022] of JP 2010-188661 A can be used.
  • a synthetic hydrophilic polymer compound can also be used as the water-soluble non-crosslinked polymer dispersant.
  • Synthetic hydrophilic polymer compounds include vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl methyl ether, polyacrylamide, polyacrylic acid or alkali metal salts thereof, acrylic resins such as water-soluble styrene acrylic resins, Water-soluble styrene maleic acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic resin, polyvinyl pyrrolidone, polyvinyl alcohol, ⁇ -naphthalene sulfonic acid formalin condensate alkali metal salt, quaternary ammonium, cation such as amino group And a high molecular compound having a salt of a functional functional group in the side chain.
  • a polymer compound containing a carboxy group is preferable from the viewpoint of dispersion stability and aggregation of the pigment, for example, an acrylic resin such as a water-soluble styrene acrylic resin, High molecular compounds containing a carboxy group such as a water-soluble styrene maleic acid resin, a water-soluble vinyl naphthalene acrylic resin, and a water-soluble vinyl naphthalene maleic resin are particularly preferred.
  • a polymer having both a hydrophobic portion and a hydrophilic portion can be used as the water-insoluble dispersant.
  • the polymer having both a hydrophobic part and a hydrophilic part include a styrene- (meth) acrylic acid copolymer, a styrene- (meth) acrylic acid- (meth) acrylic acid ester copolymer, and a (meth) acrylic acid ester.
  • -(Meth) acrylic acid copolymer polyethylene glycol (meth) acrylate- (meth) acrylic acid copolymer, styrene-maleic acid copolymer and the like.
  • Styrene- (meth) acrylic acid copolymer (meth) acrylic acid ester- (meth) acrylic acid copolymer, polyethylene glycol (meth) acrylate- (meth) acrylic acid copolymer, and styrene-maleic acid copolymer
  • the coalescence may be a binary copolymer or a ternary or higher copolymer.
  • (meth) acrylic acid ester- (meth) acrylic acid copolymer is preferable, and benzyl (meth) acrylate- (meth) acrylic acid-methyl (meth) acrylate ternary copolymer is preferable.
  • Polymers are particularly preferred.
  • (meth) acrylic acid refers to acrylic acid or methacrylic acid
  • (meth) acrylate refers to acrylate or methacrylate.
  • the copolymer may be a random copolymer, a block copolymer, or a graft copolymer.
  • the weight average molecular weight (Mw) of the non-crosslinked polymer dispersant is preferably 3,000 to 200,000, more preferably 5,000 to 100,000, still more preferably 5,000 to 80,000. Particularly preferred is 10,000 to 60,000.
  • the weight average molecular weight (Mw) of the non-crosslinked polymer dispersant is a value measured by the same method as the measurement of the weight average molecular weight (Mw) of the water-insoluble resin contained in the overcoat liquid described above.
  • the acid value of the non-crosslinked polymer dispersant is not particularly limited, but is preferably larger than the acid value of a resin (preferably a self-dispersing resin) in resin particles described later from the viewpoint of cohesiveness.
  • the crosslinked polymer dispersant is formed by crosslinking a polymer (so-called uncrosslinked polymer) with a crosslinking agent.
  • the polymer is not particularly limited, and various polymers can be used. Among them, polyvinyls, polyurethanes, polyesters and the like that can function as a water-soluble dispersant are preferable, and polyvinyls are more preferable.
  • the polymer is preferably a copolymer obtained using a carboxy group-containing monomer as a copolymerization component. Examples of the carboxy group-containing monomer include (meth) acrylic acid, ⁇ -carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, crotonic acid and the like. Among these, from the viewpoint of the crosslinkability and dispersion stability of the polymer, At least one monomer selected from (meth) acrylic acid and ⁇ -carboxyethyl acrylate is preferred.
  • the polymer Since the polymer is crosslinked by a crosslinking agent, it has a functional group that can be crosslinked by the crosslinking agent.
  • the crosslinkable functional group is not particularly limited, and examples thereof include a carboxy group or a salt thereof, an isocyanate group, and an epoxy group.
  • a carboxy group or a salt thereof is preferable from the viewpoint of improving dispersibility.
  • the acid value of the polymer is preferably 90 mgKOH / g or more, and more preferably 95 mgKOH / g or more, from the viewpoint of water solubility of the polymer. Furthermore, from the viewpoint of the dispersibility and dispersion stability of the pigment, it is preferably 100 mgKOH / g to 180 mgKOH / g, more preferably 100 mgKOH / g to 170 mgKOH / g, and 100 mgKOH / g to 160 mgKOH / g. More preferably it is.
  • the acid value of the polymer is a value measured by the method described in Japanese Industrial Standard (JIS K0070: 1992).
  • the weight average molecular weight (Mw) of the polymer is preferably 50,000 to 120,000, more preferably 60,000 to 120,000, still more preferably 60,000 to 100,000, and particularly preferably 60,000 to 90,000.
  • the weight average molecular weight (Mw) of a polymer is a value measured by the method similar to the measurement of the weight average molecular weight (Mw) of the water-insoluble resin contained in the above-mentioned overcoat liquid.
  • the polymer preferably further has at least one hydrophobic monomer as a copolymerization component.
  • the hydrophobic monomer include (meth) acrylate having an aromatic ring group such as alkyl (meth) acrylate having 1 to 20 carbon atoms, benzyl (meth) acrylate, and phenoxyethyl (meth) acrylate, styrene and derivatives thereof. It is done.
  • the copolymerization form of the polymer is not particularly limited, and the polymer may be a random polymer, a block polymer, or a graft polymer.
  • the method for synthesizing the polymer is not particularly limited, but for example, synthesis by random polymerization of vinyl monomers is preferable from the viewpoint of dispersion stability.
  • the cross-linking agent is not particularly limited as long as it is a compound having two or more sites that react with the polymer, but has two or more epoxy groups from the viewpoint of excellent reactivity with a carboxy group. (I.e., bifunctional or higher functional epoxy compounds) are preferred.
  • the crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, and polypropylene glycol.
  • the crosslinking agent is preferably at least one selected from the group consisting of polyethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether.
  • Examples of the method of coating the pigment with the crosslinked polymer dispersant include a method of dispersing the pigment using a water-soluble or water-insoluble polymer and then crosslinking the polymer with the crosslinking agent.
  • the mass ratio of pigment to dispersant is preferably in the range of 1: 0.06 to 1: 3, more preferably in the range of 1: 0.125 to 1: 2. 1: 0.125 to 1: 1.5 is more preferable.
  • the average particle diameter of the pigment (when the pigment is a resin-coated pigment, the average particle diameter of the resin-coated pigment; hereinafter the same) is preferably 10 nm to 200 nm, more preferably 10 nm to 150 nm, and more preferably 10 nm to 100 nm. Further preferred. When the average particle size is 200 nm or less, the color reproducibility is good and the droplet ejection characteristics when droplets are ejected by the ink jet method are good. When the average particle size is 10 nm or more, light resistance is improved.
  • the particle size distribution of the pigment is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution.
  • Two or more pigments having a monodispersed particle size distribution may be mixed and used.
  • the average particle diameter and particle size distribution of a pigment are calculated
  • the nanotrack particle size distribution measuring apparatus for example, UPA-EX150 manufactured by Nikkiso Co., Ltd. can be used.
  • the dye is not particularly limited, and known dyes such as those described in JP-A Nos. 2001-115066, 2001-335714, and 2002-249677 can be suitably used.
  • a dye a dye held on a water-insoluble carrier may be used.
  • the carrier holding the dye (so-called water-insoluble colored particles) can be used as an aqueous dispersion using a dispersant.
  • the carrier can be used without particular limitation as long as it is insoluble in water or hardly soluble in water.
  • the carrier may be any of inorganic materials, organic materials, and composite materials thereof. Specifically, the carriers described in JP-A Nos. 2001-181549 and 2007-169418 can be preferably used.
  • the ink composition may contain only one colorant or two or more colorants.
  • the content of the colorant (particularly the pigment) in the ink composition is preferably 1% by mass to 25% by mass with respect to the total mass of the ink composition from the viewpoint of image density, and 2% by mass to 20% by mass. Is more preferable, and 2% by mass to 10% by mass is particularly preferable.
  • the ink composition contains water and is prepared as an aqueous composition.
  • water ion-exchanged water or the like can be used.
  • the content of water in the ink composition is not particularly limited, and is preferably 10% by mass to 99% by mass, more preferably 30% by mass to 80% by mass, and 50% by mass with respect to the total mass of the ink composition. More preferably, it is 80% by mass.
  • the ink composition preferably contains resin particles. Unlike the polymer dispersant described above (that is, the polymer dispersant covering at least a part of the pigment), the resin particles are particles that exist separately from the pigment. When the ink composition contains resin particles, the resin particles are preferably aggregated by contact with an aggregating component (that is, an acid) contained in a pretreatment liquid described later. In addition, the resin particles are preferably resin particles having an anionic dissociation group other than a sulfo group from the viewpoint of excellent cohesiveness when contacted with an aggregating component contained in a pretreatment liquid described later. Details of the resin particles having an anionic dissociation group other than the sulfo group will be described later.
  • Resin particles having a sulfo group as an anionic dissociation group are not preferable in that the dispersion stability of the resin particles themselves is greatly improved, so that they do not easily aggregate even if they come into contact with the aggregating component contained in the pretreatment liquid.
  • the resin particles are preferably water-insoluble or poorly water-soluble resin particles.
  • “non-water-soluble or sparingly water-soluble” means that the resin is dried at 105 ° C. for 2 hours and then 100 g of water at 25 ° C. When dissolved in, it means that the dissolved amount is 15 g or less. From the viewpoint of improving the continuous ejection property and ejection stability of the ink, the dissolution amount is preferably 10 g or less, more preferably 5 g or less, and even more preferably 1 g or less.
  • the dissolution amount is the dissolution amount when 100% neutralized with sodium hydroxide or acetic acid depending on the type of the salt-forming group of the water-insoluble or poorly water-soluble resin.
  • the resin particles include thermoplastic, thermosetting, or modified acrylic, epoxy, polyurethane, polyether, polyamide, unsaturated polyester, phenol, silicone, or fluorine resins, Polyvinyl resins such as vinyl chloride, vinyl acetate, polyvinyl alcohol, or polyvinyl butyral, polyester resins such as alkyd resins and phthalic resins, melamine resins, melamine formaldehyde resins, aminoalkyd co-condensation resins, urea resins, urea resins, etc. Examples thereof include resin particles having an anionic group such as an amino material, a copolymer or a mixture thereof.
  • an anionic acrylic resin is, for example, an acrylic monomer having an anionic dissociative group other than a sulfo group (so-called anionic group-containing acrylic monomer) and an anionic dissociation as required. It can be obtained by polymerizing another monomer copolymerizable with a functional group-containing acrylic monomer in a solvent.
  • anionic dissociable group-containing acrylic monomer include an acrylic monomer having one or more groups selected from the group consisting of a carboxy group and a phosphonic acid group.
  • an acrylic monomer having a carboxy group (acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, fumaric acid, etc. ) Is preferred, and at least one of acrylic acid and methacrylic acid is particularly preferred.
  • the resin particles are self-dispersing resin particles (so-called self-dispersing resin particles) from the viewpoint of ejection stability of the ink composition and liquid stability (particularly dispersion stability) of the system containing the colorant. It is preferable.
  • the “self-dispersing resin” as used in the present disclosure is a functional group (especially an acidic group or a hydrophilic group of a salt thereof) possessed by the polymer itself when dispersed by the phase inversion emulsification method in the absence of a surfactant. Refers to a water-insoluble polymer that can be dispersed in an aqueous medium.
  • the “dispersed state” means an emulsified state in which a water-insoluble polymer is dispersed in an aqueous medium (so-called emulsion), and a dispersed state in which the water-insoluble polymer is dispersed in a solid state. It includes both states (so-called suspension).
  • An “aqueous medium” refers to a medium containing water.
  • the aqueous medium may contain a hydrophilic organic solvent as necessary.
  • the aqueous medium preferably contains water and 0.2% by mass or less of a hydrophilic organic solvent with respect to water, and more preferably contains only water.
  • the self-dispersing resin is preferably self-dispersing resin particles that can be in a dispersed state in which a water-insoluble polymer is dispersed in a solid state from the viewpoint of aggregation speed and fixing property when contained in the ink composition.
  • Examples of a method for obtaining an emulsified state or a dispersed state of the self-dispersing resin that is, a method for preparing an aqueous dispersion of self-dispersing resin particles include a phase inversion emulsification method.
  • a phase inversion emulsification method for example, a self-dispersing resin is dissolved or dispersed in a solvent (for example, a water-soluble organic solvent) and then poured into water as it is without adding a surfactant.
  • Examples include a method of obtaining an aqueous dispersion in an emulsified state or a dispersed state after stirring and mixing in a state in which a salt-forming group (for example, acidic group) of the resin is neutralized and mixing, and removing the solvent.
  • a salt-forming group for example, acidic group
  • a stable emulsified state or dispersed state in the self-dispersing resin is a solution in which 30 g of a water-insoluble polymer is dissolved in 70 g of an organic solvent (for example, methyl ethyl ketone).
  • Mixing agent sodium hydroxide when the salt-forming group is anionic, acetic acid when the salt-forming group is cationic
  • 200 g of water stirring (apparatus: stirring device with stirring blades, Rotational speed: 200 rpm (revolutions per minute; the same applies hereinafter), stirring time: 30 minutes, stirring temperature: 25 ° C., and even after removing the organic solvent from the mixture, the emulsified state or dispersed state is 25 ° C.
  • the emulsified state or dispersed state is 25 ° C.
  • a state that exists stably for at least one week that is, a state in which precipitation cannot be visually confirmed).
  • the stability of the emulsified state or dispersed state in the self-dispersing resin can also be confirmed by an accelerated sedimentation test by centrifugation.
  • the stability by the accelerated sedimentation test by centrifugation is, for example, that the aqueous dispersion of resin particles obtained by the above method is adjusted to a solid content concentration of 25% by mass and then centrifuged at 12,000 rpm for 1 hour. It can be evaluated by measuring the solid content concentration of the supernatant after centrifugation. If the ratio of the solid content concentration after centrifugation to the solid content concentration before centrifugation is large (that is, a value close to 1), the resin particles will not settle due to centrifugation, that is, the aqueous dispersion of resin particles. It means that things are more stable.
  • the ratio of the solid content concentration before and after centrifugation is preferably 0.8 or more, more preferably 0.9 or more, and particularly preferably 0.95 or more.
  • the self-dispersing resin preferably has a water-soluble component content that exhibits water solubility in a dispersed state of 10% by mass or less, more preferably 8% by mass or less, and 6% by mass or less. More preferably.
  • a water-soluble component content that exhibits water solubility in a dispersed state of 10% by mass or less, more preferably 8% by mass or less, and 6% by mass or less. More preferably.
  • water-soluble component refers to a compound that is contained in a self-dispersing resin and that dissolves in water when the self-dispersing resin is in a dispersed state.
  • the water-soluble component is a water-soluble compound that is by-produced or mixed when the self-dispersing resin is produced.
  • the main chain skeleton of the water-insoluble polymer is not particularly limited, and examples thereof include vinyl polymers and condensation polymers (epoxy resins, polyesters, polyurethanes, polyamides, celluloses, polyethers, polyureas, polyimides, polycarbonates, etc.).
  • vinyl polymers and condensation polymers epoxy resins, polyesters, polyurethanes, polyamides, celluloses, polyethers, polyureas, polyimides, polycarbonates, etc.
  • a vinyl polymer is particularly preferable as the main chain skeleton of the water-insoluble polymer.
  • Preferable examples of the vinyl polymer and the monomer constituting the vinyl polymer include those described in JP-A Nos. 2001-181549 and 2002-88294. Further, a radical transfer of a vinyl monomer using a chain transfer agent having a dissociable group (or a substituent that can be derived to a dissociable group), a polymerization initiator, an iniferter, a dissociable group (either an initiator or a terminator) Alternatively, a vinyl polymer in which a dissociable group is introduced at the end of a polymer chain by ionic polymerization using a compound having a substituent that can be derived from a dissociable group can also be used. In addition, preferable examples of the condensation polymer and the monomer constituting the condensation polymer include those described in JP-A-2001-247787.
  • the resin particles preferably contain a water-insoluble polymer containing a hydrophilic structural unit and a structural unit derived from an aromatic group-containing monomer or a cyclic aliphatic group-containing monomer from the viewpoint of dispersion stability.
  • the “hydrophilic structural unit” is not particularly limited as long as it is derived from a hydrophilic group-containing monomer, and may be derived from one type of hydrophilic group-containing monomer, or two or more types It may be derived from a hydrophilic group-containing monomer.
  • the hydrophilic group is not particularly limited except for a sulfo group, and may be a dissociable group or a nonionic hydrophilic group.
  • the hydrophilic group is preferably a dissociable group, more preferably an anionic dissociative group, from the viewpoint of the stability of the formed emulsified state or dispersed state. That is, the resin particles are preferably resin particles having an anionic dissociation group.
  • the dissociable group include a carboxy group and a phosphate group. Among these, the dissociable group is preferably a carboxy group from the viewpoint of fixability when the ink composition is constituted.
  • the hydrophilic group-containing monomer is preferably a dissociable group-containing monomer from the viewpoint of dispersion stability and aggregability, and more preferably a dissociable group-containing monomer having a dissociable group and an ethylenically unsaturated bond. preferable.
  • the dissociable group-containing monomer include an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer.
  • the unsaturated carboxylic acid monomer examples include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, 2-methacryloyloxymethyl succinic acid and the like.
  • unsaturated phosphoric acid monomers include vinyl phosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloxyethyl phosphate, diphenyl-2-methacryloxyethyl phosphate, dibutyl-2-acryloxy Examples thereof include ethyl phosphate.
  • an unsaturated carboxylic acid monomer is preferable from the viewpoint of dispersion stability and ejection stability, and at least one of acrylic acid and methacrylic acid is more preferable.
  • the resin particles preferably contain a polymer having a carboxy group from the viewpoint of dispersion stability and agglomeration rate when in contact with the pretreatment liquid described later, and have a carboxy group and an acid value of 25 mgKOH / g to More preferably, it contains a polymer that is 100 mg KOH / g.
  • the acid value is more preferably from 25 mgKOH / g to 80 mgKOH / g, particularly from 30 mgKOH / g to 65 mgKOH, from the viewpoint of self-dispersibility and aggregation rate when contacting with the pretreatment liquid described later. preferable.
  • the acid value of the resin particles is 25 mgKOH / g or more, the dispersion stability is good, and when it is 100 mgKOH / g or less, the cohesiveness is improved.
  • the acid value of the resin particles is a value measured by the method described in Japanese Industrial Standard (JIS K0070: 1992).
  • the aromatic group-containing monomer is not particularly limited as long as it is a compound containing an aromatic group and a polymerizable group.
  • the aromatic group may be a group derived from an aromatic hydrocarbon or a group derived from an aromatic heterocycle.
  • the aromatic group is preferably an aromatic group derived from an aromatic hydrocarbon from the viewpoint of particle shape stability in an aqueous medium.
  • the polymerizable group may be a polycondensable polymerizable group or an addition polymerizable polymerizable group.
  • the polymerizable group is preferably an addition polymerizable polymerizable group from the viewpoint of particle shape stability in an aqueous medium, and more preferably a group containing an ethylenically unsaturated bond.
  • the aromatic group-containing monomer is preferably a monomer having an aromatic group derived from an aromatic hydrocarbon and an ethylenically unsaturated bond.
  • One type of aromatic group-containing monomer may be used, or two or more types may be used in combination.
  • Examples of the aromatic group-containing monomer include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, and a styrene monomer.
  • an aromatic group-containing (meth) acrylate monomer is preferable from the viewpoint of the balance between the hydrophilicity and hydrophobicity of the polymer chain and ink fixability, and phenoxyethyl (meth) acrylate, At least one selected from the group consisting of benzyl (meth) acrylate and phenyl (meth) acrylate is more preferable, and at least one selected from the group consisting of phenoxyethyl (meth) acrylate and benzyl (meth) acrylate is more preferable.
  • the cycloaliphatic group-containing monomer is preferably a monomer having a cycloaliphatic group derived from a cycloaliphatic hydrocarbon and an ethylenically unsaturated bond, and a cycloaliphatic group-containing (meth) acrylate monomer (hereinafter, “ More preferably, it is also referred to as “alicyclic (meth) acrylate”.
  • An alicyclic (meth) acrylate includes a component derived from (meth) acrylic acid and a component derived from alcohol, and the component derived from alcohol is unsubstituted or substituted with alicyclic carbonization. It has a structure containing at least one hydrogen group (cycloaliphatic group).
  • the alicyclic hydrocarbon group may be a constituent site derived from alcohol itself, or may be bonded to a constituent site derived from alcohol via a linking group.
  • the alicyclic hydrocarbon group is not particularly limited as long as it includes a cyclic non-aromatic hydrocarbon group, and may be a monocyclic hydrocarbon group or a bicyclic hydrocarbon group. It may be a tricyclic or more polycyclic hydrocarbon group.
  • the alicyclic hydrocarbon group includes a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, a cycloalkenyl group, a bicyclohexyl group, a norbornyl group, an isobornyl group, a dicyclopentanyl group, a dicyclopentenyl group, an adamantyl group, a decahydro group.
  • the alicyclic hydrocarbon group may further have a substituent.
  • substituents include an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, a hydroxyl group, a primary amino group, a secondary amino group, a tertiary amino group, an alkylcarbonyl group, an arylcarbonyl group, and a cyano group. It is done.
  • the alicyclic hydrocarbon group may further form a condensed ring.
  • the alicyclic hydrocarbon group preferably has 5 to 20 carbon atoms in the alicyclic hydrocarbon group portion from the viewpoint of viscosity and solubility.
  • alicyclic (meth) acrylate is not limited to these specific examples.
  • monocyclic (meth) acrylates include cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate.
  • cycloalkyl (meth) acrylates having 3 to 10 carbon atoms in the cycloalkyl group such as cyclononyl (meth) acrylate and cyclodecyl (meth) acrylate.
  • examples of the bicyclic (meth) acrylate include isobornyl (meth) acrylate and norbornyl (meth) acrylate.
  • Examples of the tricyclic (meth) acrylate include adamantyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate. These alicyclic (meth) acrylates may be used alone or in combination of two or more.
  • bicyclic (meth) acrylate and tricyclic or higher polycyclic (meth) It is preferably at least one selected from the group consisting of acrylates, and at least one selected from the group consisting of isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate. More preferred.
  • the resin used for forming the resin particles is preferably an acrylic resin containing a structural unit derived from a (meth) acrylate monomer, and a structural unit derived from an aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate.
  • An acrylic resin containing is more preferable, it contains a structural unit derived from an aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate, and its content is 10% by mass to 95% by mass Is preferred.
  • the content of the aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate is 10% by mass to 95% by mass, the stability of the emulsified state or the dispersed state is improved, and the ink viscosity is further increased. Can be suppressed.
  • the content of the aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate is stable in the dispersion state, and the particle shape stability in an aqueous medium due to the hydrophobic interaction between aromatic rings or alicyclic rings.
  • the content is more preferably 15% by mass to 90% by mass, further preferably 15% by mass to 80% by mass, and more preferably 25% by mass % To 70% by mass is particularly preferable.
  • the resin used for forming the resin particles can be configured to include, for example, a structural unit derived from an aromatic group-containing monomer or a cycloaliphatic group-containing monomer and a structural unit derived from a dissociable group-containing monomer. Other structural units may be further included as necessary.
  • the monomer that forms the other structural unit is not particularly limited as long as it is a monomer copolymerizable with an aromatic group-containing monomer and a dissociable group-containing monomer.
  • an alkyl group-containing monomer is preferable from the viewpoint of flexibility of the polymer skeleton and easy control of the glass transition temperature (Tg).
  • alkyl group-containing monomers include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl.
  • Alkyl (meth) acrylates such as (meth) acrylate, hexyl (meth) acrylate, and ethylhexyl (meth) acrylate; hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4 -Ethylenically unsaturated monomers having a hydroxyl group such as hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyhexyl (meth) acrylate; dimethylaminoethyl (meth) Dialkylaminoalkyl (meth) acrylates such as acrylate; N-hydroxyalkyl (meth) acrylamides such as N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-hydroxybutyl (meth) acrylamide; N- Methoxymethyl (meth
  • the weight average molecular weight (Mw) of the water-insoluble polymer constituting the resin particles is preferably 3,000 to 200,000, more preferably 5,000 to 150,000, and 10,000 to 100,000. More preferably, it is 000.
  • the weight average molecular weight (Mw) of the water-insoluble polymer is a value measured by the same method as the measurement of the weight average molecular weight (Mw) of the water-insoluble resin contained in the overcoat liquid described above.
  • the water-insoluble polymer constituting the resin particle is a structural unit derived from an aromatic group-containing (meth) acrylate monomer (preferably a structural unit derived from phenoxyethyl (meth) acrylate and / or from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. Or a structural unit derived from benzyl (meth) acrylate) or a cycloaliphatic group-containing monomer (preferably alicyclic (meth) acrylate), and a copolymerization ratio of 15% by mass to 80% by mass of the total mass of the resin particles. It is preferable to include.
  • the water-insoluble polymer has a copolymerization ratio of 15% by mass to 80% by mass of a structural unit derived from an aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate monomer from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer.
  • % A structural unit derived from a carboxy group-containing monomer, and a structural unit derived from an alkyl group-containing monomer (preferably a structural unit derived from an alkyl ester of (meth) acrylic acid).
  • the water-insoluble polymer preferably has an acid value of 25 mgKOH / g to 100 mgKOH / g, a weight average molecular weight (Mw) of 3,000 to 200,000, and an acid value of 25 mgKOH / g to 95 mgKOH. More preferably, the weight average molecular weight (Mw) is 5,000 to 150,000.
  • the acid value of the water-insoluble polymer is a value measured by the method described in Japanese Industrial Standard (JIS K0070: 1992).
  • B-01 Phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (50/45/5)
  • B-02 Phenoxyethyl acrylate / benzyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (30/35/29/6)
  • B-03 Phenoxyethyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (50/44/6)
  • B-04 Phenoxyethyl acrylate / methyl methacrylate / ethyl acrylate / acrylic acid copolymer (30/55/10/5)
  • B-05 benzyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (35/59/6)
  • B-06 Styrene / phenoxyethyl acrylate / methyl methacrylate / acrylic acid copo
  • the method for producing the water-insoluble polymer contained in the resin particles is not particularly limited.
  • a method for producing a water-insoluble polymer emulsion polymerization is carried out in the presence of a polymerizable surfactant to covalently bond the surfactant and the water-insoluble polymer, the hydrophilic group-containing monomer and the aromatic group-containing monomer.
  • a method of copolymerizing a monomer mixture containing an alicyclic group-containing monomer by a known polymerization method such as a solution polymerization method or a bulk polymerization method may be used.
  • the polymerization method is preferably a solution polymerization method, more preferably a solution polymerization method using an organic solvent, from the viewpoint of the aggregation rate and droplet ejection stability when an ink composition is used.
  • the resin particles include a polymer synthesized in an organic solvent from the viewpoint of aggregation rate, the polymer has an anionic group (preferably a carboxy group), and preferably has an acid value of 20 mgKOH / g to 100 mgKOH / g), and a part or all of anionic groups (preferably carboxy groups) of the polymer are preferably neutralized and prepared as a polymer dispersion having water as a continuous phase. That is, the production of the resin particles includes a step of synthesizing a polymer in an organic solvent, and a dispersion step of forming an aqueous dispersion in which at least a part of an anionic group (preferably a carboxy group) of the polymer is neutralized. It is preferable to provide it.
  • the dispersion step preferably includes the following step (1) and step (2).
  • Step (1) A step of stirring a mixture containing a polymer (that is, a water-insoluble polymer), an organic solvent, a neutralizing agent, and an aqueous medium.
  • Step (2) A step of removing the organic solvent from the mixture.
  • Step (1) is a step in which a polymer (that is, a water-insoluble polymer) is first dissolved in an organic solvent, and then a neutralizing agent and an aqueous medium are gradually added and mixed, followed by stirring to obtain a dispersion. It is preferable. By adding a neutralizing agent and an aqueous medium to a water-insoluble polymer solution dissolved in an organic solvent, resin particles having a particle size with higher storage stability can be obtained without requiring strong shearing force. it can.
  • the stirring method of a mixture is not specifically limited, The stirring method using the mixing stirring apparatus generally used is mentioned. Moreover, you may stir a mixture using dispersers, such as an ultrasonic disperser and a high-pressure homogenizer, as needed.
  • step (2) the aqueous dispersion of resin particles is obtained by distilling off the organic solvent from the dispersion obtained in step (1) by a conventional method such as distillation under reduced pressure and phase-inversion into an aqueous system. Obtainable.
  • the organic solvent in the obtained aqueous dispersion is substantially removed, and the amount of the organic solvent is preferably 0.2% by mass or less, more preferably 0.1% by mass or less.
  • the organic solvent include alcohol solvents, ketone solvents, and ether solvents.
  • the organic solvent for example, the organic solvent exemplified in paragraph [0059] of JP 2010-188661 A can be used.
  • the neutralizing agent the neutralizing agents exemplified in paragraphs [0060] to [0061] of JP 2010-188661 A can be used.
  • the average particle size of the resin particles is preferably 10 nm to 400 nm, more preferably 10 nm to 200 nm, still more preferably 10 nm to 100 nm, and particularly preferably 10 nm to 50 nm.
  • the particle size distribution of the resin particles is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution. Two or more kinds of resin particles having a monodisperse particle size distribution may be mixed and used.
  • the average particle diameter and particle size distribution of the resin particles are obtained by measuring the volume average particle diameter by a dynamic light scattering method using a nanotrack particle size distribution measuring apparatus.
  • a nanotrack particle size distribution measuring apparatus for example, UPA-EX150 manufactured by Nikkiso Co., Ltd. can be used.
  • the ink composition may contain only one type of resin particles (preferably self-dispersing resin particles), or may contain two or more types.
  • the content of the resin particles (preferably self-dispersing resin particles) in the ink composition is, for example, 1% by mass to 30% by mass with respect to the total mass of the ink composition from the viewpoint of glossiness of the image. Preferably, 3% by mass to 15% by mass is more preferable.
  • the ink composition may contain components other than the above components.
  • examples of other components include organic solvents, surfactants, and other additives.
  • the ink composition preferably further contains an organic solvent.
  • an organic solvent particularly a water-soluble organic solvent
  • the “water-soluble organic solvent” in the present disclosure refers to an organic solvent that dissolves 5 g or more in 100 g of water at 20 ° C.
  • a water-soluble organic solvent having a vapor pressure lower than that of water is preferable.
  • the water-soluble organic solvent suitable for preventing drying include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2 , 6-hexanetriol, acetylene glycol derivatives, polyhydric alcohols such as glycerin and trimethylolpropane, ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether, Lower alkyl ethers of polyhydric alcohols such as tripropylene glycol monomethyl (or ethyl) ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imida Rijinon, hetero
  • water-soluble organic solvents suitable for promoting penetration include ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, tripropylene glycol monomethyl (or ethyl) ether, and 1,2-hexanediol. Examples include alcohol. These water-soluble organic solvents can exhibit good effects when contained in the ink composition in an amount of 5 to 30% by mass. In addition, these water-soluble organic solvents are preferably used within a range of addition amounts that do not cause printing, image bleeding, and paper loss (so-called print-through).
  • the water-soluble organic solvent can be used for adjusting the viscosity.
  • Specific examples of water-soluble organic solvents that can be used to adjust the viscosity include alcohols (methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol).
  • polyhydric alcohols ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol Etc.
  • glycol derivatives ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol Monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, triethylene glycol monomethyl ether, ethylene glycol di Acetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether,
  • the ink composition may contain only one type of organic solvent or two or more types of organic solvent.
  • the content of the organic solvent in the ink composition is preferably 10% by mass to 50% by mass with respect to the total mass of the ink composition.
  • the ink composition may further contain a surfactant.
  • a surfactant it may contain only one kind of surfactant or two or more kinds.
  • the surfactant examples include nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants and the like.
  • the surfactant an anionic surfactant or a nonionic surfactant is preferable from the viewpoint of aggregation rate.
  • the surfactant content in the ink composition is determined so that the surface tension of the ink composition (25 ° C.) is 25 mN / It is preferably an amount that can be adjusted to m or more and 40 mN / m or less, and more preferably an amount that can be adjusted to 27 mN / m to 37 mN / m.
  • Surfactants can also be used as antifoaming agents.
  • a fluorine compound, a silicone compound, a chelating agent such as ethylenediaminetetraacetic acid (EDTA), or the like can also be used.
  • the ink composition can further contain other additives in addition to the above components.
  • Other additives include, for example, antifading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, antiseptics, antifungal agents, pH adjusters, antifoaming agents, viscosity modifiers, dispersion stabilizers, and rust inhibitors.
  • Known additives such as agents and chelating agents are included. These various additives may be added directly after the ink composition is prepared, or may be added when the ink composition is prepared.
  • the pH adjuster a neutralizing agent (organic base, inorganic alkali, etc.) can be used.
  • the pH adjuster is preferably added so that the pH of the ink composition (25 ° C.) is 6 to 10, and the pH is 7 to 10. It is more preferable to add.
  • the pH of the ink composition is preferably 6 to 10 and more preferably 7 to 10 from the viewpoint of improving the storage stability of the ink composition.
  • the pH of the ink composition is a value measured using a pH meter in a state where the temperature of the ink composition is adjusted to 25 ° C. in an environment of 25 ° C.
  • As the pH meter for example, WM-50EG manufactured by Toa DK Corporation can be used.
  • the viscosity of the ink composition is preferably in the range of 1 mPa ⁇ s to 30 mPa ⁇ s, from the viewpoint of ejection stability when ejected by the ink jet method, and aggregation rate when using a pretreatment liquid described later.
  • the range of s to 20 mPa ⁇ s is more preferred, the range of 2 mPa ⁇ s to 15 mPa ⁇ s is still more preferred, and the range of 2 mPa ⁇ s to 10 mPa ⁇ s is particularly preferred.
  • the viscosity of the ink composition is measured at 25 ° C. using VISCOMETER TV-22 (Toki Sangyo Co., Ltd.).
  • the surface tension of the ink composition is not particularly limited and can be, for example, 20 mN / m or more. From the viewpoint of better droplet ejection by the inkjet method, it is preferably 23 mN / m to 40 mN / m, more preferably 26 mN / m to 37 mN / m.
  • the surface tension of the ink composition is a value measured at 25 ° C. by a plate method using a surface tension meter.
  • As the surface tension meter for example, Automatic Surface Tensiometer CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. can be used.
  • the surface tension of the ink composition can be adjusted, for example, by adding a surfactant.
  • the pretreatment liquid contains an acid and water, and may further contain other components as necessary.
  • the pretreatment liquid contains an acid.
  • the pretreatment liquid contains an acid as a compound (aggregating component) that aggregates at least the colorant contained in the ink composition.
  • the acid acts on at least the colorant which is a dispersed component in the ink composition. Since at least the colorant aggregates, a sharper image can be obtained.
  • Examples of the acid include organic acidic compounds and inorganic acidic compounds that can lower the pH of the ink composition.
  • an organic acidic compound For example, the compound which has a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfo group, a sulfinic acid group, a carboxy group etc. is mentioned.
  • the organic acidic compound a compound having a phosphate group or a carboxy group is preferable, and a compound having a carboxy group is more preferable from the viewpoint of the aggregation rate of the dispersion component (at least the colorant) in the ink composition.
  • Examples of the compound having a carboxy group include polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid (preferably DL-malic acid), maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, Tartaric acid, phthalic acid, 4-methylphthalic acid, lactic acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, these Examples thereof include salts (for example, polyvalent metal salts).
  • the compound having a carboxy group is preferably a divalent or higher carboxylic acid (polyvalent carboxylic acid) from the viewpoint of the aggregation rate of the dispersion component (at least the colorant) in the ink composition, and malonic acid, malic acid, maleic acid. More preferably at least one polycarboxylic acid selected from the group consisting of succinic acid, glutaric acid, fumaric acid, tartaric acid, 4-methylphthalic acid, and citric acid, and malonic acid, malic acid, tartaric acid, and citric acid. Particularly preferred is at least one selected from the group consisting of
  • the organic acidic compound preferably has a low pKa. Dispersion stability is reduced by bringing the surface charge of particles such as pigments and polymer particles in the ink composition stabilized by a weakly acidic functional group such as a carboxy group into contact with an organic acidic compound having a lower pKa. Can be reduced.
  • an acidic compound having a low pKa, a high solubility in water, and a valence of 2 or more is preferable, and a functional group (for example, carboxy group) that stabilizes the particles in the ink composition.
  • a divalent or trivalent acidic compound having a high buffer capacity in a pH range lower than the pKa of the group) is more preferable.
  • inorganic acidic compounds include phosphoric acid, phosphoric acid compounds, nitric acid, nitrous acid, sulfuric acid, hydrochloric acid and the like.
  • phosphoric acid and a phosphoric acid compound are preferable from the viewpoint of suppressing the roughness of the image and the aggregation rate of the dispersion component (at least the colorant) in the ink composition.
  • Phosphoric acid has a low water solubility (25 ° C.) of 0.0018 g / 100 g of water when calcium salt (that is, calcium phosphate) is used. Therefore, when the inorganic acidic compound contained in the pretreatment liquid is phosphoric acid, the calcium salt is not dissolved but immobilized, and the effect of suppressing the roughness generated on the surface of the image area is high. In particular, when a recording medium having a coating layer containing calcium carbonate is used as the recording medium, phosphoric acid is advantageous as the inorganic acidic compound contained in the pretreatment liquid.
  • Examples of the phosphoric acid compound include phosphorous acid, hypophosphorous acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid, and salts thereof.
  • the pretreatment liquid may contain only one kind of acid, or may contain two or more kinds.
  • the acid content in the pretreatment liquid is preferably 5% by mass to 40% by mass and more preferably 10% by mass to 30% by mass with respect to the total mass of the pretreatment liquid.
  • the content of the acid as an aggregating component in the pretreatment liquid is 5% by mass or more, the roughness of the image is further suppressed.
  • the content of the acid that is an aggregating component in the pretreatment liquid is 40% by mass or less, the abrasion resistance of the image is further improved.
  • the content ratio of the organic acidic compound and the inorganic acidic compound in the pretreatment liquid is: From the viewpoint of the aggregation rate of the ink composition and the suppression of roughness of the image, 5 mol% to 50 mol% is preferable, 10 mol% to 40 mol% is more preferable, and 15 mol% to 35 mol% is still more preferable.
  • the pretreatment liquid contains water and is prepared as an aqueous composition.
  • water ion-exchanged water or the like can be used.
  • the content of water in the pretreatment liquid is not particularly limited, and is preferably 10% by mass to 99% by mass, more preferably 50% by mass to 90% by mass, and 60% by mass with respect to the total mass of the pretreatment liquid. More preferably, it is 80% by mass.
  • the pretreatment liquid may contain components other than the above components.
  • examples of other components include organic solvents, nitrogen-containing heterocyclic compounds, antifoaming agents, and other additives.
  • the pretreatment liquid preferably further contains an organic solvent.
  • a water-soluble organic solvent is preferable.
  • the water-soluble organic solvent include the same water-soluble organic solvents that can be contained in the ink composition described above.
  • polyalkylene glycol or a derivative thereof is preferable from the viewpoint of curling suppression. Diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, dipropylene glycol, tripropylene glycol monoalkyl ether, At least one selected from the group consisting of oxypropylene glyceryl ether and polyoxyethylene polyoxypropylene glycol is more preferable.
  • the pretreatment liquid may contain only one organic solvent or two or more organic solvents.
  • the content of the organic solvent in the pretreatment liquid is not particularly limited.
  • 1% by mass to 30% by mass is preferable, and 5% by mass to 15% by mass is more preferable.
  • the pretreatment liquid may further contain a nitrogen-containing heterocyclic compound.
  • the pretreatment liquid contains a nitrogen-containing heterocyclic compound, the abrasion resistance of the image is further improved.
  • a nitrogen-containing 5-membered ring structure or a nitrogen-containing 6-membered ring structure is preferable, and a nitrogen-containing 5-membered ring structure is more preferable.
  • a nitrogen-containing 5-membered ring structure and the nitrogen-containing 6-membered ring structure a 5-membered or 6-membered heterostructure containing at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom A ring structure is preferred.
  • the heterocycle may be condensed with a carbon aromatic ring or a heteroaromatic ring.
  • Heterocycles include tetrazole, triazole, imidazole, thiadiazole, oxadiazole, selenadiazole, oxazole, thiazole, benzoxazole, benzothiazole, benzimidazole, pyrimidine, and triazaine. Examples include a den ring, a tetraazaindene ring, and a pentaazaindene ring.
  • the heterocycle may have a substituent.
  • Substituents include nitro groups, halogen atoms (chlorine atoms, bromine atoms, etc.), mercapto groups, cyano groups, substituted or unsubstituted alkyl groups (eg, methyl, ethyl, propyl, t-butyl, cyanoethyl groups, etc.) ), Aryl groups (eg, phenyl, 4-methanesulfonamidophenyl, 4-methylphenyl, 3,4-dichlorophenyl, naphthyl, etc.), alkenyl groups (eg, allyl groups), aralkyl groups (eg, Benzyl, 4-methylbenzyl, phenethyl, etc.), sulfonyl groups (eg, methanesulfonyl, ethanesulfonyl, p-toluenesulfonyl,
  • nitrogen-containing heterocyclic compound examples include imidazole, benzimidazole, benzoindazole, benzotriazole, tetrazole, benzoxazole, benzothiazole, pyridine, quinoline, pyrimidine, piperidine, piperazine, quinoxaline, morpholine and the like.
  • nitrogen-containing heterocyclic compounds may have a substituent such as the above alkyl group, carboxy group, or sulfo group.
  • the nitrogen-containing 6-membered ring compound a compound having a triazine ring, a pyrimidine ring, a pyridine ring, a pyrroline ring, a piperidine ring, a pyridazine ring or a pyrazine ring is preferable, and a compound having a triazine ring or a pyrimidine ring is more preferable.
  • the nitrogen-containing 6-membered ring compound may have a substituent.
  • substituents examples include an alkyl group having 1 to 6 carbon atoms (preferably 1 to 3), an alkoxy group having 1 to 6 carbon atoms (preferably 1 to 3), a hydroxyl group, a carboxy group, a mercapto group, and 1 carbon atom. And an alkoxyalkyl group having 6 to 6 (preferably 1 to 3), a hydroxyalkyl group having 1 to 6 carbon atoms (preferably 1 to 3), and the like.
  • the nitrogen-containing 6-membered ring compound include triazine, methyltriazine, dimethyltriazine, hydroxyethyltriazine ring, pyrimidine, 4-methylpyrimidine, pyridine, pyrroline and the like.
  • the pretreatment liquid may contain an antifoaming agent.
  • the antifoaming agent include silicone compounds (that is, silicone antifoaming agents) and pluronic compounds (that is, pluronic antifoaming agents).
  • silicone compounds that is, silicone antifoaming agents
  • pluronic compounds that is, pluronic antifoaming agents
  • an antifoamer a silicone type antifoamer is preferable.
  • the silicone-based antifoaming agent a silicone-based antifoaming agent having a polysiloxane structure is preferable.
  • a defoaming agent As a defoaming agent, a commercially available product may be used.
  • examples of commercially available antifoaming agents include BYK-012, BYK-017, BYK-021, BYK-022, BYK-024, BYK-025, BYK-038, BYK-094 (above, BYK Chemie Japan, Inc. )), KS-537, KS-604, KM-72F (Shin-Etsu Chemical Co., Ltd.), TSA-739 (Momentive Performance Materials Japan GK), Olfin (registered trademark) AF104 (Nissin) Chemical Industry Co., Ltd.).
  • silicone-based antifoaming agents such as BYK-017, BYK-021, BYK-022, BYK-024, BYK-025, BYK-094, KS-537, KS-604, At least one selected from the group consisting of KM-72F and TSA-739 is preferred, and BYK-024 is particularly preferred from the viewpoint of ejection stability of the ink composition.
  • the content of the antifoaming agent in the pretreatment liquid is preferably 0.0001% by mass to 1% by mass, and 0.001% by mass with respect to the total mass of the pretreatment liquid. % To 0.1% by mass is more preferable.
  • the amount of the silicone oil is 0.005% by mass to 0.02% by mass.
  • the pretreatment liquid may contain water-insoluble resin particles.
  • the pretreatment liquid may contain water-insoluble resin particles.
  • water-insoluble resin particles By including the water-insoluble resin particles in the pretreatment liquid, most of the water-insoluble resin particles are unevenly distributed on the surface of the recording material after the pretreatment liquid is applied, and the wettability of the surface of the recording material is improved. .
  • an aggregating component ie, acid
  • the droplets are prevented from coalescing, and the droplet size becomes a desired size.
  • the pretreatment liquid contains water-insoluble resin particles, the occurrence of streak-like unevenness that tends to occur in the recorded image is suppressed. Furthermore, roughness in the image can also be suppressed.
  • “graininess” means that after the ink composition has landed on the recording material, the droplets coalesce, causing minute density unevenness in the image and pixel uniformity. A phenomenon that decreases.
  • the “water-insoluble” of the water-insoluble resin is synonymous with the “water-insoluble” of the resin (water-insoluble resin) in the “resin particles” contained in the above-described overcoat liquid. That is, it is synonymous with “water-insoluble or poorly water-soluble” defined in the above-mentioned section of the overcoat solution.
  • the water-insoluble resin in the water-insoluble resin particles includes a structural unit derived from a monomer containing at least one group selected from a sulfo group and a salt of the sulfo group, and a structural unit derived from a monomer containing an aromatic ring structure. It is preferable to have at least, and if necessary, it may further have structural units derived from other monomers.
  • Examples of the structural unit derived from a monomer having at least one group selected from a sulfo group and a salt of a sulfo group include acrylamide-2-methylpropanesulfonic acid, acrylamide-2-methylpropanesulfonic acid salt, styrene Examples include structural units derived from sulfonic acid, ⁇ -methylstyrene sulfonic acid, 3-sulfopropyl (meth) acrylate, and the like.
  • the counter ion in the salt is preferably Na ion, K ion, Li ion, or Al ion.
  • the structural unit derived from a monomer having at least one group selected from a sulfo group and a salt of a sulfo group a structural unit derived from acrylamide-2-methylpropanesulfonic acid is preferable.
  • a structural unit derived from a monomer containing an aromatic ring structure a structural unit derived from styrene is preferable.
  • a structural unit derived from another monomer a structural unit derived from an acrylate ester monomer is preferable.
  • the water-insoluble resin constituting the particles preferably has a weight average molecular weight (Mw) of 3,000 to 150,000.
  • Mw weight average molecular weight
  • the weight average molecular weight (Mw) of the water-insoluble resin that can be contained in the pretreatment liquid is measured by the same method as the measurement of the weight average molecular weight (Mw) of the water-insoluble resin contained in the overcoat liquid described above. Value.
  • the glass transition temperature (Tg) of the water-insoluble resin constituting the particles is preferably 40 ° C. or higher and 120 ° C.
  • Tg of the water-insoluble resin is 40 ° C. or higher, the storage stability of the pretreatment liquid is good.
  • the Tg of the water-insoluble resin is 120 ° C. or less, the change in the texture of the recording material before and after the pretreatment liquid is applied is reduced.
  • the Tg of the water-insoluble resin is a value measured by the same method as the measurement of the Tg of the water-insoluble resin contained in the overcoat liquid described above.
  • the average particle size of the water-insoluble resin particles is preferably 10 nm to 300 nm, more preferably 15 nm to 150 nm in terms of volume average particle size.
  • the particle size distribution of the water-insoluble resin particles is not particularly limited, and may be either a wide particle size distribution or a monodisperse particle size distribution. Further, two or more kinds of water-insoluble resin particles having a monodisperse particle size distribution may be mixed and used.
  • the average particle size and particle size distribution of the water-insoluble resin particles are determined by measuring the volume average particle size by a dynamic light scattering method using a nanotrack particle size distribution measuring device.
  • a nanotrack particle size distribution measuring apparatus for example, UPA-EX150 manufactured by Nikkiso Co., Ltd. can be used.
  • the pretreatment liquid can further contain other additives in addition to the above components.
  • Other additives are the same as other additives in the ink composition described above.
  • the pH of the pretreatment liquid is preferably 7.0 or less, more preferably 0.5 to 3.5, and still more preferably 0.5 to 2.0 from the viewpoint of the aggregation rate of the ink composition.
  • the pH of the pretreatment liquid is a value measured using a pH meter in a state where the temperature of the pretreatment liquid is adjusted to 25 ° C in an environment of 25 ° C.
  • As the pH meter for example, WM-50EG manufactured by Toa DK Corporation can be used.
  • surface tension of a pretreatment liquid there is no restriction
  • the surface tension of the pretreatment liquid is a value measured at 25 ° C. by a plate method using a surface tension meter.
  • As the surface tension meter for example, Automatic Surface Tensiometer CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. can be used.
  • the surface tension of the pretreatment liquid can be adjusted, for example, by adding a surfactant.
  • the viscosity of the pretreatment liquid is preferably 1 mPa ⁇ s to 30 mPa ⁇ s, more preferably 1 mPa ⁇ s to 20 mPa ⁇ s, further preferably 2 mPa ⁇ s to 15 mPa ⁇ s, from the viewpoint of the aggregation rate of the ink composition. • s to 10 mPa ⁇ s is particularly preferable.
  • the viscosity of the pretreatment liquid is a value measured under the condition of 25 ° C. using VISCOMETER TV-22 (Toki Sangyo Co., Ltd.).
  • the ink set of the present disclosure includes at least one overcoat liquid described above, at least one ink composition described above, and a pretreatment liquid described above. As long as it contains at least one kind, another liquid may be included.
  • the image forming method of the present disclosure includes a step of applying a pretreatment liquid containing acid and water to a recording material (hereinafter also referred to as a “pretreatment step”), and a pretreatment liquid application surface of the recording material.
  • a step of forming an image by applying an ink composition containing a colorant and water (hereinafter also referred to as an “image forming step”), and at least a part of the recording material on which the image is formed.
  • a step of applying an overcoat solution containing the resin particles having a group represented by (1) and having no carboxy group, and water (hereinafter also referred to as “overcoat step”). Have.
  • the image forming method of the present disclosure may include processes other than the pretreatment process, the image forming process, and the overcoat process as necessary.
  • the above-described ink set is used for image formation, and the image is overcoated. Therefore, even when an image is formed using an acid-containing treatment liquid, the glossiness of the image forming surface is high. It becomes good.
  • each step in the image forming method of the present disclosure will be described.
  • the details of the ink composition, the pretreatment liquid, the ink composition, and the overcoat liquid, as well as the preferred embodiments, have been described in detail in the section of the ink set, and thus the description thereof is omitted here.
  • a substrate having a contact angle (water contact angle) of 70 ° or more when 3 seconds have passed since a water droplet was applied to the surface is suitable.
  • the recording material include paper base materials such as coated paper and synthetic paper, and polymer base materials such as polyethylene terephthalate (PET) film.
  • PET polyethylene terephthalate
  • a paper base material is preferable and has a coating layer in that the effect of suppressing density reduction and streaky unevenness (and roughness in some cases) in the solid image portion appears remarkably.
  • a paper base material (so-called coated paper) is more preferable.
  • the contact angle with water on the surface of the recording material is determined according to the method described in Japanese Industrial Standard (JIS R3257) using a contact angle meter (product name: Dropmaster DM700, Kyowa Interface Science Co., Ltd.) Measured at room temperature and humidity.
  • JIS R3257 Japanese Industrial Standard
  • a contact angle meter product name: Dropmaster DM700, Kyowa Interface Science Co., Ltd.
  • the coated paper is one in which a coating layer containing an inorganic pigment or the like is provided on the surface of high-quality paper or neutral paper that is generally not surface-treated and mainly comprises cellulose as a support. Coated paper tends to cause uneven gloss in the image area, but effectively suppresses uneven gloss in the image area when the pretreatment liquid contains phosphoric acid or a phosphoric acid compound. Can do.
  • the coated paper is preferably art paper, coated paper, lightweight coated paper, or fine coated paper.
  • the inorganic pigment contained in the coating layer is not particularly limited, for example, silica, kaolin, clay, calcined clay, zinc oxide, tin oxide, magnesium sulfate, aluminum oxide, aluminum hydroxide, pseudoboehmite, calcium carbonate, It is preferably at least one selected from the group consisting of satin white, aluminum silicate, smectite, zeolite, magnesium silicate, magnesium carbonate, magnesium oxide, and diatomaceous earth, and at least selected from the group consisting of calcium carbonate, silica, and kaolin. One type is more preferable.
  • the recording material a commercially available product can be used.
  • Examples of commercially available recording materials include “Bon Ivory” from Oji Paper Co., Ltd., “MagnoStarGloss” from Sappi, “Carolina C2S” from International, “CartaIntegra” from Metsaboard, “VJFP series” from YUPO. Etc.
  • the application amount of the pretreatment liquid and the application amount of the ink composition are adjusted as necessary.
  • the amount of the pretreatment liquid applied may be changed in order to adjust the physical properties such as the viscoelasticity of the aggregate formed by mixing the pretreatment liquid and the ink composition according to the recording material.
  • a pretreatment liquid containing acid and water is applied to the recording material.
  • the pretreatment liquid can be applied by a known method such as a coating method, an ink jet method, or an immersion method.
  • the coating method include known coating methods using a bar coater, an extrusion die coater, an air doctor coater, a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, a bar coater and the like. Details of the inkjet method will be described later.
  • the pretreatment process is provided before the image forming process using the ink composition. That is, before applying the ink composition onto the recording material, a pretreatment liquid for aggregating the dispersion components (colorant, etc.) in the ink composition is applied in advance, and then applied onto the recording material. The ink composition is applied so as to come into contact with the pretreatment liquid, and an image is formed. Thereby, inkjet recording can be speeded up, and a fine image with high density and resolution can be obtained even at high speed recording.
  • the pretreatment liquid on the recording material is preferably heat-dried after the pretreatment liquid is applied onto the recording material and before the ink composition is applied. Accordingly, bleeding is prevented, ink colorability is improved, and a visible image having good color density and hue can be recorded.
  • Heating and drying can be performed by a known heating means such as a heater, a blowing means using blowing air such as a dryer, or a combination of a known heating means and a blowing means.
  • a heating method for example, a method of applying heat with a heater or the like from the side opposite to the side to which the pretreatment liquid of the recording material is applied, or hot air or hot air is applied to the side of the recording material to which the pretreatment liquid has been applied.
  • the method or the method of heating using an infrared heater is mentioned. Heating may be performed by combining a plurality of these heating methods.
  • an image is formed by applying an ink composition containing a colorant and water to the application surface of the pretreatment liquid of the recording material.
  • the ink jet method is not particularly limited.
  • a charge control method that ejects ink using electrostatic attraction
  • a drop-on-demand method that uses vibration pressure of a piezoelectric element
  • an electric signal as an acoustic beam.
  • acoustic ink jet method that uses ink to irradiate ink and ejects ink using radiation pressure
  • thermal ink jet method bubble jet (registered trademark)) method that uses ink to form bubbles by heating ink Either may be sufficient.
  • the ink jet method in particular, the method described in Japanese Patent Application Laid-Open No.
  • the ink jet method for discharging can be used effectively.
  • the inkjet method includes a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method using is included.
  • An ink jet head used in the ink jet method may be an on-demand method or a continuous method.
  • Discharge methods include electro-mechanical conversion methods (single cavity type, double cavity type, bender type, piston type, shear mode type, shared wall type, etc.), electro-thermal conversion methods (thermal ink jet type, bubble jet ( (Registered trademark) type), electrostatic attraction method (electric field control type, slit jet type, etc.), discharge method (spark jet type, etc.), and any of these discharge methods may be used.
  • electro-mechanical conversion methods single cavity type, double cavity type, bender type, piston type, shear mode type, shared wall type, etc.
  • electro-thermal conversion methods thermal ink jet type, bubble jet ( (Registered trademark) type)
  • electrostatic attraction method electric field control type, slit jet type, etc.
  • discharge method spark jet type, etc.
  • an ink jet head As an ink jet head, a single serial head is used, and a shuttle system that performs recording while scanning the head in the width direction of the recording material, and recording elements are arranged corresponding to the entire area of one side of the recording material.
  • a line system using a line head In the line method, an image can be formed on the entire surface of the recording material by scanning the recording material in a direction orthogonal to the arrangement direction of the recording elements, and a carriage system such as a carriage for scanning a short head is unnecessary. Become. Further, since complicated scanning control of the carriage movement and the recording material is not required, and only the recording material moves, the recording speed can be increased as compared with the shuttle system.
  • the image forming step is preferably started within 10 seconds after the preprocessing step, and more preferably within 0.1 seconds to 10 seconds. Thereby, an image can be formed at high speed.
  • Start within 10 seconds after the pretreatment step means that the time from the application of the pretreatment liquid and the completion of drying to the first ink droplet landing on the recording material is within 10 seconds. means.
  • the amount of ink droplets to be applied is preferably 1.5 pL (picoliter) to 3.0 pL, and preferably 1.5 pL to 2. More preferably, it is 5 pL.
  • the amount of ink droplets can be adjusted by appropriately selecting the ejection conditions in the ink jet method according to the ink composition to be ejected.
  • the image forming method of the present disclosure may further include a heat fixing step of heat fixing the image recorded through the preprocessing step and the image forming step. According to the heat fixing step, the image on the recording material is fixed, and the abrasion resistance of the image is further improved.
  • the heating in the heat fixing step is preferably performed at a temperature equal to or higher than the minimum film-forming temperature (MFT) of the resin particles in the image.
  • MFT minimum film-forming temperature
  • the pressure at the time of pressurization is preferably 0.1 MPa to 3.0 MPa, more preferably 0.1 MPa to 1.0 MPa, and further preferably 0.1 MPa to 0.5 MPa in terms of surface smoothing. .
  • the heating method is not particularly limited, and for example, a method of heating with a heating element such as a nichrome wire heater, a method of supplying warm air or hot air, a method of heating with a halogen lamp, an infrared lamp, or the like, and drying without contact.
  • the method of making it suitable is.
  • the method of heating and pressing is not particularly limited. For example, a method of pressing a hot plate against the image forming surface of the recording material, a pair of heating and pressing rollers, a pair of heating and pressing belts, or an image of the recording material.
  • a heating and pressing apparatus having a heating and pressing belt arranged on the forming surface side and a holding roller arranged on the opposite side, heat fixing is performed by contacting them, such as a method of passing a pair of rollers. The method is preferred.
  • a preferable nip time is 1 to 10 seconds, more preferably 2 to 1 second, and further preferably 4 to 100 milliseconds.
  • the preferable nip width is 0.1 mm to 100 mm, more preferably 0.5 mm to 50 mm, and still more preferably 1 mm to 10 mm.
  • the heat and pressure roller may be a metal metal roller, a coating layer made of an elastic body around a metal core, and a surface layer (also referred to as a “release layer”) as necessary. May be provided.
  • the latter core metal can be formed of a cylindrical body made of, for example, iron, aluminum, or stainless steel (SUS), and the surface of the core metal is preferably at least partially covered with a coating layer.
  • the covering layer is particularly preferably formed of a silicone resin or fluororesin having releasability.
  • a heating element is built in one core metal of the heat and pressure roller, and the heat treatment and the pressure treatment are performed simultaneously by passing a recording material between the rollers, or If necessary, the recording material may be sandwiched and heated using two heating rollers.
  • a heating element a halogen lamp heater, a ceramic heater, a nichrome wire or the like is preferable.
  • the thickness of the base material is preferably 10 ⁇ m to 100 ⁇ m.
  • the material of the belt base material aluminum, iron, polyethylene or the like can be used in addition to nickel.
  • the thickness of the layer formed using these resins is preferably 1 ⁇ m to 50 ⁇ m, and more preferably 10 ⁇ m to 30 ⁇ m.
  • elastic members such as springs having tension are provided at both ends of the roller such as a heat pressure roller so that a desired nip pressure can be obtained in consideration of the nip gap. Select and install.
  • the recording material conveyance speed is preferably 200 mm / second to 700 mm / second, more preferably 300 mm / second to 650 mm / second, and 400 mm / second to 600 mm / second. Further preferred.
  • the recording material has a group represented by the formula (1) on at least a part on the side where the image is formed in the image forming process (and in some cases, the heat fixing process), and carboxy.
  • An overcoat liquid containing resin particles having no group and water is applied.
  • the overcoat liquid can be applied by a known method such as a coating method, an ink jet method, or an immersion method.
  • a coating method such as a coating method, an ink jet method, or an immersion method.
  • the coating method include the same as the known coating methods in the above-described pretreatment step.
  • the overcoat process is provided after the image forming process using the ink composition. That is, after a desired image is formed by applying the ink composition on the recording material, at least a part of the image forming surface including the image of the recording material (at least on the side where the image of the recording material is formed) Apply an overcoat solution to a part).
  • the overcoat may be applied only on the image forming surface, only on the image portion where the image is formed, only on the non-image portion where the image is not formed, or on the entire image forming surface. It is preferable that an overcoat is applied to the entire image forming surface. Thereby, the glossiness on the image forming surface of the recording material is effectively improved.
  • overcoat solution preferably, the coating weight
  • 2.0g / m 2 ⁇ 6.0g / m 2 are preferred, 3.0g / m 2 ⁇ 5.0g / m 2 Is more preferable.
  • the volume average particle diameter of resin (including water-insoluble resin) particles was measured by the following method. That is, after preparing a water dispersion whose volume average particle diameter of the resin particles is adjusted so that the solid content concentration of the water dispersion of the resin particles is 2% by mass, and adjusting the liquid temperature to 25 ° C. Measurement was performed by a dynamic light scattering method using a nanotrack particle size distribution measuring apparatus (product name: UPA-EX150, Nikkiso Co., Ltd.).
  • the mixture was further reacted for 3 hours, and then water was added to adjust the solid content concentration of the resin particles to 30% by mass to obtain an aqueous dispersion of resin particles A-1.
  • the volume average particle size of the resin particles A-1 in the obtained aqueous dispersion was 35 nm as measured by the method described above.
  • the weight average molecular weight (Mw) of the resin contained in the particles A-1 was 50,000 as measured by the method described above.
  • the total content of the group represented by the formula (1) in the resin contained in the particles A-1 was calculated and found to be 0.24 g per 1 g of resin.
  • Resin particles A-2 were prepared in the same manner as in the production of resin particles A-1, except that the raw material monomers used in the production of resin particles A-1 were changed as shown in Table 1 below.
  • An aqueous dispersion of ⁇ A-15 was obtained.
  • the volume average particle diameter of the resin particles A-2 to A-15 and the weight average molecular weight (Mw) of the resin contained in the particles A-2 to A-15 in the obtained aqueous dispersion are described above. Measured by the method. Further, the total content of the group represented by the formula (1) in the resins contained in the particles A-2 to A-15 was calculated. The results are shown in Table 1.
  • Resin particles R-1 were prepared in the same manner as in the production of resin particles A-1, except that the raw material monomers used in the production of resin particles A-1 were changed as shown in Table 1 below.
  • An aqueous dispersion of ⁇ R-3 was obtained.
  • the volume average particle diameter of the resin particles R-1 to R-3 and the weight average molecular weight (Mw) of the resin contained in the particles R-1 to R-3 in the obtained aqueous dispersion are described above. Measured by the method. Further, the total content of the group represented by the formula (1) in the resins contained in the particles R-1 to R-3 was calculated. The results are shown in Table 1.
  • resin particles in the present disclosure that is, resin particles having a group represented by the formula (1) and not having a carboxy group
  • resin particles those not corresponding to the resin particles in are referred to as “comparative resin particles”.
  • the numerical values described in the column of the raw material monomer in Table 1 indicate the amount of the raw material monomer used (unit: part by mass), and “-” means that the raw material monomer is not used.
  • composition -75% by weight of aqueous dispersion of resin particles A-1 obtained above ⁇ Wax dispersion 15% by mass (AQUACER (registered trademark) 531, BYK-Chemie) ⁇ Isopropyl alcohol (IPA) 3% by mass ⁇ Butyl carbitol 1% by mass ⁇ Sulfosuccinic acid-di-2-ethylhexyl sodium 1% by mass ⁇ Ion-exchanged water Total amount of 100% by mass
  • overcoat solutions 2-19- Other than changing the aqueous dispersion of resin particles A-1 to any of aqueous dispersions of resin particles A-2 to A-16 and R-1 to R-3 in the preparation of overcoat liquid 1
  • overcoat solutions 2 to 19 were prepared.
  • the pH values of the obtained overcoat solutions 2 to 19 were measured by the method described above, and all were within the range of 6.4 to 8.7. Further, the surface tensions of the overcoat liquids 2 to 19 were measured by the method described above, and all were within the range of 25.3 mN / m to 33.6 mN / m.
  • Each component shown to the following composition was mixed and the pretreatment liquid 1 was prepared. It was 0.8 when the pH of the obtained pretreatment liquid was measured by the above-mentioned method. Moreover, it was 32.8 mN / m when the surface tension of the pretreatment liquid was measured by the method described above.
  • composition ⁇ Diethylene glycol monoethyl ether 4% by mass ⁇ Tripropylene glycol monomethyl ether 4% by mass -Malonic acid (organic acid) 17.3% by mass Propane tricarboxylic acid (organic acid) 4.3% by mass ⁇ Phosphoric acid (inorganic acid) 4.3% by mass -5% by mass of the following water-insoluble resin particles C-1 ⁇ Benzotriazole 1% by mass ⁇ Antifoaming agent
  • the amount of silicone oil to be 0.01% by mass (Product name: TSA-739, solid content: 15% by mass, emulsion type silicone antifoaming agent, Momentive Performance Materials Japan GK) ⁇ Ion-exchanged water Total amount of 100% by mass
  • the weight average molecular weight (Mw) of the polymer dispersant P-1 was 44,600 as measured by the method described above. Furthermore, when the acid value of the polymer dispersant P-1 was measured by a method based on JIS standard (JIS K 0070: 1992), it was 65.2 mgKOH / g.
  • the methyl ethyl ketone was removed from the obtained dispersion at 55 ° C. under reduced pressure, and a part of the water was further removed. Then, using a high-speed centrifugal cooler 7550 (Kubota Co., Ltd.), 50 ml Centrifugation was performed for 30 minutes at a rotation speed of 8,000 rpm using a centrifuge tube. After centrifugation, the supernatant liquid other than the precipitate was collected. Thereafter, the pigment concentration was determined from the absorbance spectrum, and a dispersion (cyan pigment dispersion C) of resin-coated pigment particles (pigment coated with a polymer dispersant) having a pigment concentration of 10.2% by mass was obtained. The average particle diameter of the resin-coated pigment particles in the obtained cyan pigment dispersion C was 105 nm. The average particle size was measured by the method described above.
  • the copolymer contained in the obtained polymer solution had a weight average molecular weight (Mw) of 64,000 and an acid value of 38.9 mgKOH / g.
  • Mw weight average molecular weight
  • the acid value and the weight average molecular weight were measured by the methods described above.
  • an aqueous dispersion (emulsion) of resin particles (B-01) having a solid content concentration of 28.0% by mass was obtained.
  • Each structural unit in the resin of the resin particle (B-01) is shown below.
  • the number of each structural unit in the following formula represents “mass ratio”.
  • Each prepared ink composition was filtered through a polyvinylidene fluoride (PVDF) 5 ⁇ m filter (Millex SV, diameter: 25 mm, Millipore) connected to a plastic disposable syringe, and four inks (magenta ink M1, black) Ink 1 composed of ink K1, cyan ink C1, and yellow ink Y1) was obtained.
  • the pH of the obtained ink 1 was measured by the above-described method and found to be 8.2. Further, the viscosity of the ink 1 was measured by the above-described method and found to be 37.6 mPa ⁇ s.
  • Examples 1 to 16 and Comparative Examples 1 to 3> Using ink 1, pretreatment liquid 1, and overcoat liquids 1 to 19 prepared as described above, ink sets 1 to 19 shown in Table 4 below were produced. Images were formed and evaluated by the following procedures using the ink sets 1 to 19 prepared.
  • the pretreatment liquid 1 was applied onto the substrate using an application bar. The coating was performed with the coating amount of the pretreatment liquid 1 being 1.5 g / m 2 . Next, the pretreatment liquid 1 coated on the substrate was dried under the following conditions.
  • Image formation step Ink 1 (magenta ink M1, black ink K1, cyan ink C1, and yellow ink Y1) is ejected on the side of the base material on which the pretreatment liquid 1 has been applied, under the following conditions.
  • a multicolor image was formed. Specifically, ink of each color was applied (droplet ejected) on the pretreatment liquid-coated surface of the substrate coated with the pretreatment liquid 1 under the following conditions to form an image.
  • Head Head with 1,200 dpi (dots per inch) / 20 inch wide piezo full line heads for 4 colors
  • the ink 1 applied to the pretreatment liquid coating surface of the substrate was dried under the following conditions.
  • an overcoat solution (overcoat) is applied to the entire image forming surface of the substrate on which an image is formed using a roller coater (product name: Digi Coater POD, Toyotec Co., Ltd.). Any one of the coating liquids 1 to 19) was applied by the roller coater described above, so that the image forming surface of the substrate was post-treated to prepare an image sample.
  • the post-treatment was performed by coating the overcoat solution on the image forming surface of the substrate with a coating amount of 4.0 g / m 2 .
  • the overcoat solution coated on the image forming surface of the substrate was dried under the following conditions.
  • ⁇ Condition Temperature and heating method: Heating was performed from the surface of the substrate using an infrared heater so that the surface temperature of the substrate was 40 ° C. Conveying speed: 30m / min
  • Evaluation 1 Calculate the average value of the measured value in the direction parallel to the coating direction of the overcoat liquid and the measured value in the direction perpendicular to the coating direction of the overcoat solution as the gloss value, and use the calculated average value as the gloss value to evaluate the following: Evaluation was made according to criteria.
  • the average glossiness is 60 or more.
  • 4 Average glossiness is 50 or more and less than 60.
  • 3 The average glossiness was 40 or more and less than 50, and a highly glossy overcoat surface was obtained.
  • 2 The average glossiness is 30 or more and less than 40, and a high gloss overcoat surface is not obtained.
  • 1 The average value of glossiness was less than 30.
  • -Evaluation criteria- 5 The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 0 or more and less than 5.
  • 4 The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 5 or more and less than 10.
  • 3 The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 10 or more and less than 15, which is practically acceptable.
  • 2 The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 15 or more and less than 20, and the difference in gloss between the parallel direction and the vertical direction is clearly visually recognized and is not practically acceptable. It is. 1: The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 20 or more.
  • -Evaluation criteria- 5 The rubbed portion was not different from the rubbed portion, and no scratch was observed. 4: Although the surface of the rubbed portion is slightly scratched, there is no damage as an image and there is no practical problem. 3: The surface of the rubbed part was slightly peeled off and very fine scratches were observed, but this is not a problem in practical use. 2: The surface of the rubbed part is peeled off, scratches are conspicuous, and impede practically. 1: The image of the rubbed part is peeled off, and the white background of the coated paper is partially exposed, causing a practical problem.
  • -Evaluation criteria- 5 The part to which ion exchange water is attached is not different from the part to which ion exchange water is not attached, and no change is observed. 4: Although the trace part of the part of the part which ion-exchange water adhered adhered a little, there is no problem practically. 3: A trace was weakly attached to the entire surface of the portion to which the ion-exchanged water was adhered, but it was practically acceptable. 2: The mark is clearly attached to the portion where the ion exchange water is adhered, and it is practically hindered. 1: The overcoat of the part to which ion-exchange water adhered is lost, and it is unacceptable practically.
  • the ink sets of Examples 1 to 16 including an overcoat solution containing resin particles having a group represented by the formula (1) and not having a carboxy group were used.
  • the image sample prepared in this way had very good gloss.
  • grains of the resin which has group represented by Formula (1), and does not have a carboxy group was favorable in storage stability.
  • the image samples produced using the ink sets of Examples 1 to 16 also had good abrasion resistance and water resistance.
  • An image sample produced using the ink set of Comparative Example 3 having an overcoat solution containing resin particles having a group represented by the formula (1) but also having a carboxy group is an ink set of Example 1 or the like.
  • the gloss was remarkably inferior as compared with the image sample produced using.

Abstract

Provided are an ink set and an application thereof, the ink set having: an ink composition containing a coloring agent and water; a pretreatment liquid containing an acid and water; and an overcoat liquid containing water and particles of a resin which has a group represented by formula (1) and does not have a carboxy group. In formula (1), A represents an alkylene group having two or three carbon atoms, R represents a hydrogen atom or a hydrocarbon group having 1-20 carbon atoms, and m represents an integer of 3-40.

Description

インクセット及び画像形成方法Ink set and image forming method
　本開示は、インクセット及び画像形成方法に関する。 The present disclosure relates to an ink set and an image forming method.
　インクジェット法を利用した記録方法は、インクジェットヘッドに設けられた多数のノズルからインクを液滴状に吐出することにより、多種多様な基材に対して高品位の画像を記録できること等の理由から広く利用されている。インクジェット法を利用した画像形成方法には、種々の形態が提案されており、例えば、着色剤を含むインクと、インク中の成分を凝集させる化合物を含む前処理液と、を併用したインクセットを使用する方法が知られている。この方法では、インクと前処理液とを接触させることで、例えば、解像度に優れた画像を形成することができる。 The recording method using the ink jet method is widely used because a high-quality image can be recorded on a wide variety of substrates by ejecting ink in droplets from a number of nozzles provided in the ink jet head. It's being used. Various forms of image forming methods using the inkjet method have been proposed. For example, an ink set using an ink containing a colorant and a pretreatment liquid containing a compound that aggregates the components in the ink is used. The method to use is known. In this method, for example, an image with excellent resolution can be formed by bringing the ink and the pretreatment liquid into contact with each other.
　一方、従来から、画像に求められる要求は高く、画像の解像度及び色再現が良好であるだけでなく、写真のような光沢感及び画像が外部から受ける外力（例えば、引っ掻き又は擦過）に対する耐性も備えていることが重要とされている。 On the other hand, there has been a high demand for images in the past, and not only the resolution and color reproduction of images are good, but also the glossiness like a photograph and the resistance to external force (for example, scratching or scratching) that the image receives from the outside. It is important to have it.
　上記のうち、特に画像の光沢性を高める技術として、インク画像上にオーバーコート液を付与して画像をオーバーコートすることにより画像に高光沢性を与える技術が知られており、所謂、水性ニスを用いる技術が提案されている。 Among the above, as a technique for increasing the glossiness of an image in particular, a technique for imparting high glossiness to an image by applying an overcoat liquid on an ink image and overcoating the image is known. A technique that uses this has been proposed.
　具体的な例として、クエン酸を含む反応液が塗布された記録媒体にブラックインクで画像を印刷した後、樹脂粒子分散体等を用いたクリアインクを全面に印字して画像を記録する技術が開示されている（例えば、特開２０１５－１９９７８０号公報参照）。
　また、塩化マグネシウム等の多価金属塩及び樹脂粒子を含む水性処理液が塗布された記録媒体の被記録面に、顔料インクで記録を行い、その後さらに、被記録面に同じ水性処理液を塗布して皮膜を形成する技術が開示されている（例えば、特開２００３－３２６８２９号公報参照）。
　さらに、記録媒体のインクジェットインクを吐出した面に、水分散性ポリウレタンと、２種類の特定化合物と、水とを含有するオーバーコート液を塗布する技術が開示されている（例えば、特開２０１５－１７２１２４号公報参照）。 As a specific example, there is a technique for printing an image with a black ink on a recording medium coated with a reaction liquid containing citric acid, and then printing the clear ink using a resin particle dispersion or the like on the entire surface to record the image. (For example, refer to JP-A-2015-199780).
In addition, recording is performed with a pigment ink on a recording surface of a recording medium on which an aqueous treatment liquid containing a polyvalent metal salt such as magnesium chloride and resin particles is applied, and then the same aqueous treatment liquid is further applied to the recording surface. Thus, a technique for forming a film is disclosed (for example, see Japanese Patent Application Laid-Open No. 2003-326829).
Further, a technique is disclosed in which an overcoat liquid containing water-dispersible polyurethane, two kinds of specific compounds, and water is applied to the surface of the recording medium on which the inkjet ink is ejected (for example, Japanese Patent Application Laid-Open No. 2015-2015). No. 172124).
　しかしながら、特開２０１５－１９９７８０号公報に開示された技術では、画像上に印字されるクリアインクに含まれる樹脂に、カルボキシ基を有するアクリル酸が含まれているため、画像形成の際、反応液中の酸によって、クリアインク中の樹脂粒子等の成分が凝集しやすく、結果として高光沢な画像は得られない。
　また、特開２００３－３２６８２９号公報に開示された技術では、顔料インクで記録された画像上に水性処理液の皮膜が形成されるものの、皮膜の形成には前処理に用いた水性処理液と同じ液が用いられ、しかも水性処理液に含まれる凝集剤が多価金属塩である。多価金属塩は、酸と比較して、インク中の樹脂粒子等の成分に対する凝集力が弱いため、画像の光沢低下という課題は生じ難いが、画像の鮮鋭さが不十分なものとなる。 However, in the technique disclosed in JP-A-2015-199780, the resin contained in the clear ink printed on the image contains acrylic acid having a carboxy group. Components such as resin particles in the clear ink tend to aggregate due to the acid therein, and as a result, a high gloss image cannot be obtained.
Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 2003-326829, an aqueous treatment liquid film is formed on an image recorded with pigment ink. The same liquid is used, and the flocculant contained in the aqueous treatment liquid is a polyvalent metal salt. Since the polyvalent metal salt has a weak cohesive force with respect to components such as resin particles in the ink as compared with the acid, the problem of reducing the glossiness of the image hardly occurs, but the sharpness of the image becomes insufficient.
　一般に、オーバーコート液（所謂、水性ニス）として上市されている市販品は、樹脂粒子等の成分がカルボン酸により分散安定化されているものが多い。そのため、前処理液中に凝集剤として含まれる酸の作用を利用して画像を形成すると、インク中に分散含有されている顔料等と同様に、酸の作用によりオーバーコート液中に分散されている樹脂粒子等の成分の凝集が生じやすい。オーバーコート液中で凝集が起きると、オーバーコート液は増粘する。これにより、オーバーコート液を塗布した際、塗膜の表面に凹凸が生じ、膜の光沢が低下する。特開２０１５－１７２１２４号公報に記載のオーバーコート液も、製造方法の具体例として記載されている特許第３６６１０４７号公報の内容から明らかなように、カルボキシ基を分散安定化基とする樹脂粒子（即ち、水分散性ポリウレタンの粒子）を含有しているため、樹脂粒子の凝集による増粘が生じ、高光沢な膜は得られないと考えられる。 Generally, many commercial products marketed as overcoat liquids (so-called aqueous varnishes) have components such as resin particles dispersed and stabilized with carboxylic acid. Therefore, when an image is formed by utilizing the action of an acid contained as a flocculant in the pretreatment liquid, it is dispersed in the overcoat liquid by the action of the acid, as in the case of pigments dispersed and contained in the ink. Aggregation of components such as resin particles tends to occur. When aggregation occurs in the overcoat liquid, the overcoat liquid thickens. Thereby, when the overcoat liquid is applied, irregularities are generated on the surface of the coating film, and the gloss of the film is lowered. The overcoat liquid described in JP-A-2015-172124 is also a resin particle having a carboxy group as a dispersion stabilizing group, as is apparent from the content of Japanese Patent No. 366047 described as a specific example of the production method (see FIG. That is, it is considered that a highly glossy film cannot be obtained due to the increase in viscosity due to aggregation of the resin particles.
　このような膜の光沢性の低下は、非硬化型の水系のオーバーコート液（所謂、水性ニス）において生じやすい現象である。近年の環境適性及び安全性の観点からは、凝集による増粘現象が生じ難い水系のオーバーコート液が求められることが予想される。 Such a decrease in the glossiness of the film is a phenomenon that tends to occur in a non-curing aqueous overcoat liquid (so-called aqueous varnish). From the viewpoint of environmental suitability and safety in recent years, it is expected that a water-based overcoat solution that does not easily cause a thickening phenomenon due to aggregation is required.
　また、樹脂粒子等が分散して含有されているオーバーコート液においては、良好な保存安定性が求められる。 In addition, in an overcoat liquid in which resin particles and the like are dispersed and contained, good storage stability is required.
　本発明の一実施形態は、オーバーコート液の保存安定性が良好で、かつ、酸性の前処理液を用いて画像が形成される被記録材料の画像形成面をオーバーコートした場合に良好な光沢性が得られるインクセットを提供することに関する。
　本発明の他の実施形態は、良好な光沢性が得られる画像形成方法を提供することに関する。 In one embodiment of the present invention, the storage stability of the overcoat liquid is good, and the gloss is good when the image forming surface of the recording material on which an image is formed is overcoated using an acidic pretreatment liquid. The present invention relates to providing an ink set capable of obtaining the characteristics.
Another embodiment of the present invention relates to providing an image forming method capable of obtaining good glossiness.
　上記課題を解決するための手段には、以下の態様が含まれる。
　＜１＞　着色剤及び水を含むインク組成物と、酸及び水を含む前処理液と、下記の式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子、及び水を含むオーバーコート液と、を有するインクセット。 Means for solving the above problems include the following aspects.
<1> An ink composition containing a colorant and water, a pretreatment liquid containing an acid and water, and a resin particle having a group represented by the following formula (1) and having no carboxy group And an overcoat liquid containing water.
Figure JPOXMLDOC01-appb-C000003
 
Figure JPOXMLDOC01-appb-C000003
 
　式（１）中、Ａは、炭素数２又は３のアルキレン基を表し、Ｒは、水素原子又は炭素数１～２０の炭化水素基を表し、ｍは、３以上４０以下の整数を表す。 In formula (1), A represents an alkylene group having 2 or 3 carbon atoms, R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and m represents an integer of 3 to 40.
　＜２＞　粒子に含まれる樹脂中の、式（１）で表される基の合計含有量は、樹脂１ｇ当たり、０．０５ｇ以上０．５０ｇ以下である＜１＞に記載のインクセット。
　＜３＞　粒子に含まれる樹脂は、下記の式（２）で表される少なくとも１種の構成単位と、下記の式（３）及び下記の式（４）からなる群より選ばれる少なくとも１種の構成単位と、を含む＜１＞又は＜２＞に記載のインクセット。 <2> The ink set according to <1>, wherein the total content of the group represented by the formula (1) in the resin contained in the particles is 0.05 g or more and 0.50 g or less per 1 g of the resin.
<3> The resin contained in the particles is at least one selected from the group consisting of at least one structural unit represented by the following formula (2), the following formula (3), and the following formula (4). The ink set according to <1> or <2>, comprising:
Figure JPOXMLDOC01-appb-C000004
 
Figure JPOXMLDOC01-appb-C000004
 
　式（２）中、Ａは、炭素数２又は３のアルキレン基を表し、Ｒは、水素原子又は炭素数１～２０の炭化水素基を表し、Ｒ１は、水素原子又はメチル基を表し、ｍは、３以上４０以下の整数を表す。 In formula (2), A represents an alkylene group having 2 or 3 carbon atoms, R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R 1 represents a hydrogen atom or a methyl group, m represents an integer of 3 to 40.
　式（３）中、Ｒ２は、水素原子又はメチル基を表し、Ｒ３は、炭素数１～２０の炭化水素基を表す。 In formula (3), R 2 represents a hydrogen atom or a methyl group, and R 3 represents a hydrocarbon group having 1 to 20 carbon atoms.
　＜４＞　式（２）におけるｍは、６以上２０以下の整数を表す＜３＞に記載のインクセット。
　＜５＞　粒子は、式（１）で表される基を有するノニオン性界面活性剤を含む＜１＞～＜４＞のいずれか１つに記載のインクセット。
　＜６＞　被記録材料に、酸及び水を含む前処理液を付与する工程と、被記録材料の前処理液の付与面に、着色剤及び水を含むインク組成物を付与して画像を形成する工程と、被記録材料の画像が形成された側の少なくとも一部に、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子、及び水を含むオーバーコート液を付与する工程と、を有する画像形成方法。 <4> The ink set according to <3>, wherein m in the formula (2) represents an integer of 6 or more and 20 or less.
<5> The ink set according to any one of <1> to <4>, wherein the particles include a nonionic surfactant having a group represented by the formula (1).
<6> Forming an image by applying a pretreatment liquid containing acid and water to the recording material, and applying an ink composition containing a colorant and water to the application surface of the pretreatment liquid of the recording material And a resin particle having a group represented by the formula (1) and not having a carboxy group on at least a part of the recording material on which an image is formed, and over containing water. Applying the coating liquid.
　本発明の一実施形態によれば、オーバーコート液の保存安定性が良好で、かつ、酸性の前処理液を用いて画像が形成される被記録材料の画像形成面をオーバーコートした場合に良好な光沢性が得られるインクセットが提供される。
　本発明の他の実施形態によれば、良好な光沢性が得られる画像形成方法が提供される。 According to an embodiment of the present invention, the storage stability of the overcoat solution is good, and the image forming surface of the recording material on which an image is formed using an acidic pretreatment solution is good. Provided is an ink set capable of obtaining high glossiness.
According to another embodiment of the present invention, an image forming method capable of obtaining good glossiness is provided.
　以下、本発明を適用したインクセット及び画像形成方法の一例について説明する。但し、本発明は、以下の実施形態に何ら限定されるものではなく、本発明の実施形態の目的の範囲内において、適宜、変更を加えて実施することができる。 Hereinafter, an example of an ink set and an image forming method to which the present invention is applied will be described. However, the present invention is not limited to the following embodiment, and can be implemented with appropriate modifications within the scope of the object of the embodiment of the present invention.
　本開示において「～」を用いて示された数値範囲は、「～」の前後に記載される数値をそれぞれ最小値及び最大値として含む範囲を意味する。
　本開示に段階的に記載されている数値範囲において、ある数値範囲で記載された上限値又は下限値は、他の段階的な記載の数値範囲の上限値又は下限値に置き換えてもよい。また、本開示に記載されている数値範囲において、ある数値範囲で記載された上限値又は下限値は、実施例に示されている値に置き換えてもよい。
　本開示において、２以上の好ましい態様の組み合わせは、より好ましい態様である。
　本開示において、各成分の含有量は、各成分に該当する物質が複数種存在する場合には、特に断らない限り、複数種の物質の合計の含有量を意味する。 In the present disclosure, a numerical range indicated by using “to” means a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In a numerical range described in stages in the present disclosure, an upper limit value or a lower limit value described in a numerical range may be replaced with an upper limit value or a lower limit value in another numerical range. Further, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.
In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.
In the present disclosure, the content of each component means the total content of the plurality of types of substances unless there is a specific notice when there are a plurality of types of substances corresponding to the respective components.
　本開示において、「工程」の用語は、独立した工程だけではなく、他の工程と明確に区別できない場合であっても、その工程の所期の目的が達成されれば本用語に含まれる。 In the present disclosure, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes.
　本開示において、「（メタ）アクリル」は、アクリル及びメタクリルの両方を包含する概念で用いられる語である。 In the present disclosure, “(meth) acryl” is a term used in a concept including both acrylic and methacrylic.
［インクセット］
　本開示のインクセットは、着色剤及び水を含むインク組成物と、酸及び水を含む前処理液と、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子、及び水を含むオーバーコート液と、を有する。
　本開示のインクセットは、オーバーコート液の保存安定性が良好で、かつ、酸性の前処理液を用いて画像が形成される被記録材料の画像形成面をオーバーコートした場合に良好な光沢性が得られる。 [Ink set]
An ink set of the present disclosure includes an ink composition containing a colorant and water, a pretreatment liquid containing an acid and water, a resin having a group represented by the formula (1) and having no carboxy group And an overcoat liquid containing water.
The ink set of the present disclosure has good storage stability of the overcoat liquid, and good gloss when the image forming surface of a recording material on which an image is formed is overcoated using an acidic pretreatment liquid Is obtained.
　従来から、画像上をオーバーコート処理することにより、被記録材料の画像を有する側の表面の光沢性又は画像の耐久性を高める技術が知られている。例えば、特開２０１５－１９９７８０号公報及び特開２００３－３２６８２９号公報には、画像上に樹脂粒子を分散させて含む液を与えることにより、画像の擦過又は水に対する耐性を改善する技術が開示されている。
　インクジェット法で画像を形成する方式のうち、顔料等を含むインク組成物に加え、インク組成物中の顔料等を凝集させる凝集剤を含む前処理液を使用する方式では、前処理液に接触させてインク組成物を打滴し画像形成した後、樹脂粒子等の成分を含む液で画像をオーバーコートする際に、オーバーコートされた液中の成分が凝集し増粘することで、オーバーコートによる光沢の改善効果が低下する場合がある。
　例えば、特開２００３－３２６８２９号公報のように、水性処理液中に含まれる凝集剤が多価金属塩である場合には、多価金属塩は分散成分の凝集作用が酸に比べて弱いため、画像をオーバーコートした際の液中成分の凝集に伴う増粘は少ないことが予想される。しかし、例えば、特開２０１５－１９９７８０号公報のように、酸を含む反応液で前処理された被記録材料に形成された画像をオーバーコートする場合には、オーバーコートされる液中の樹脂粒子等の成分が凝集することによる増粘が顕著になる結果、オーバーコート面に凹凸が生じ、オーバーコートによる光沢改善効果が著しく損なわれるという問題が生じ得る。また、特開２０１５－１７２１２４号公報に記載のオーバーコート液も、カルボキシ基を分散安定化基とする樹脂粒子（即ち、水分散性ポリウレタンの粒子）を含有しているため、樹脂粒子の凝集による増粘が生じ、高光沢な膜は得られないと考えられる。
　また、一般に、樹脂粒子等が分散含有されているオーバーコート液においては、良好な保存安定性が求められる。 2. Description of the Related Art Conventionally, there has been known a technique for improving the glossiness of the surface of an image-recording material side or the durability of an image by overcoating the image. For example, JP-A-2015-199780 and JP-A-2003-326829 disclose a technique for improving image abrasion or water resistance by providing a liquid containing resin particles dispersed on an image. ing.
Among the methods for forming an image by the inkjet method, in a method using a pretreatment liquid containing an aggregating agent for aggregating the pigment in the ink composition in addition to the ink composition containing the pigment or the like, it is brought into contact with the pretreatment liquid. After the ink composition is ejected and an image is formed, when the image is overcoated with a liquid containing components such as resin particles, the components in the overcoated liquid aggregate and thicken. The effect of improving gloss may be reduced.
For example, as in JP-A-2003-326829, when the aggregating agent contained in the aqueous treatment liquid is a polyvalent metal salt, the polyvalent metal salt has a weaker aggregating action of the dispersed component than the acid. It is expected that the viscosity increase due to the aggregation of the components in the liquid when the image is overcoated is small. However, for example, as in JP-A-2015-199780, when an image formed on a recording material pretreated with a reaction liquid containing an acid is overcoated, resin particles in the liquid to be overcoated As a result of the thickening due to the aggregation of the components, etc., the overcoat surface is uneven, and the gloss improvement effect by the overcoat may be significantly impaired. In addition, the overcoat liquid described in JP-A-2015-172124 also contains resin particles having a carboxy group as a dispersion stabilizing group (that is, water-dispersible polyurethane particles), and therefore, due to aggregation of the resin particles. It is thought that thickening occurs and a highly glossy film cannot be obtained.
In general, in an overcoat liquid in which resin particles and the like are dispersed and contained, good storage stability is required.
　これに対し、本開示のインクセットでは、酸を含む水系の前処理液（以下、「酸含有処理液」ともいう。）及びインク組成物に、酸含有処理液を用いて形成された画像をオーバーコートする液として、特定の基（即ち、式（１）で表される基）を有し、かつ、カルボキシ基を有さない樹脂の粒子を含む水系のオーバーコート液を組み合わせることで、酸含有処理液を用いて画像が形成される被記録材料の画像形成面をオーバーコートした場合であっても良好な光沢性が得られる。すなわち、本開示のインクセットでは、酸含有処理液を用いて形成された画像をオーバーコートした場合でも、酸含有処理液の酸の作用によるオーバーコート液中の成分の凝集による増粘が抑えられるため、光沢の低下を招く筋状等のムラの発生が効果的に抑制される。その結果、オーバーコート処理を行うことによる画像の光沢改善効果が良好に奏されると考えられる。
　また、オーバーコート液に含まれる樹脂の粒子を形成する樹脂は、特定の基（即ち、式（１）で表される基）を有し、かつ、カルボキシ基を有さないため、本開示におけるオーバーコート液は、保存安定性が良好である。 On the other hand, in the ink set of the present disclosure, an image formed using an acid-containing treatment liquid in an aqueous pretreatment liquid containing an acid (hereinafter also referred to as “acid-containing treatment liquid”) and an ink composition. By combining an aqueous overcoat solution containing resin particles having a specific group (that is, a group represented by the formula (1)) and not having a carboxy group as the overcoat solution, Even when the image forming surface of a recording material on which an image is formed is overcoated using the containing treatment liquid, good glossiness can be obtained. That is, in the ink set of the present disclosure, even when an image formed using an acid-containing processing liquid is overcoated, thickening due to aggregation of components in the overcoat liquid due to the action of an acid in the acid-containing processing liquid can be suppressed. Therefore, the occurrence of irregularities such as streaks that cause a decrease in gloss is effectively suppressed. As a result, it is considered that the effect of improving the glossiness of the image by performing the overcoat treatment is excellent.
In addition, since the resin forming the resin particles contained in the overcoat liquid has a specific group (that is, a group represented by the formula (1)) and does not have a carboxy group, The overcoat solution has good storage stability.
　以下、本開示のインクセットに含まれるインク組成物、前処理液、及びオーバーコート液のうち、オーバーコート液について最初に説明し、次いで、インク組成物及び前処理液について説明する。 Hereinafter, of the ink composition, the pretreatment liquid, and the overcoat liquid included in the ink set of the present disclosure, the overcoat liquid will be described first, and then the ink composition and the pretreatment liquid will be described.
＜オーバーコート液＞
　オーバーコート液は、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子、及び水を含む。
　オーバーコート液は、水系液体である。オーバーコート液は、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子を含むことにより、保存安定性が良好となる。また、オーバーコート液は、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子を含むことにより、酸を含む前処理液を用いて形成した画像形成面をオーバーコートした場合であっても良好な光沢が得られる。 <Overcoat solution>
The overcoat liquid contains particles of a resin having a group represented by the formula (1) and not having a carboxy group, and water.
The overcoat liquid is an aqueous liquid. When the overcoat liquid contains a resin particle having a group represented by the formula (1) and not having a carboxy group, the storage stability is improved. Further, the overcoat liquid has an image forming surface formed by using a pretreatment liquid containing an acid by containing particles of a resin having a group represented by the formula (1) and not having a carboxy group. Even when the film is overcoated, good gloss can be obtained.
（樹脂の粒子）
　オーバーコート液は、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子を含む。 (Resin particles)
The overcoat liquid contains resin particles having a group represented by the formula (1) and not having a carboxy group.
～樹脂～
　粒子を形成する樹脂としては、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂であって、水系液体中で粒子の形状を保つことができれば、特に制限されず、公知の樹脂の中から適宜選択することができ、好ましくは、非水溶性又は難水溶性の樹脂（以下、粒子を形成する樹脂を「水不溶性樹脂」ともいう。）である。
　ここで、「非水溶性又は難水溶性」であるとは、樹脂を１０５℃で２時間乾燥させた後、２５℃の水１００ｇ中に溶解させた場合に、その溶解量が１５ｇ以下であることをいう。溶解量は、非水溶性又は難水溶性の樹脂の塩生成基の種類に応じて、水酸化ナトリウム又は酢酸で１００％中和した際の溶解量である。 ~ Resin ~
The resin forming the particles is not particularly limited as long as it has a group represented by the formula (1) and does not have a carboxy group and can maintain the shape of the particles in an aqueous liquid. The resin can be appropriately selected from known resins, and is preferably a water-insoluble or poorly water-soluble resin (hereinafter, the resin forming the particles is also referred to as “water-insoluble resin”).
Here, “water-insoluble or poorly water-soluble” means that when the resin is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., the dissolved amount is 15 g or less. That means. The dissolution amount is the dissolution amount when 100% neutralized with sodium hydroxide or acetic acid according to the type of the salt-forming group of the water-insoluble or poorly water-soluble resin.
Figure JPOXMLDOC01-appb-C000005
 
Figure JPOXMLDOC01-appb-C000005
 
　式（１）中、Ａは、炭素数２又は３のアルキレン基を表し、Ｒは、水素原子又は炭素数１～２０の炭化水素基を表し、ｍは、３以上４０以下の整数を表す。 In formula (1), A represents an alkylene group having 2 or 3 carbon atoms, R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and m represents an integer of 3 to 40.
　水不溶性樹脂は、式（１）で表される基を１種のみ有していてもよいし、２種以上有していてもよい。
　式（１）におけるＡは、炭素数２又は３のアルキレン基を表す。
　炭素数２又は３のアルキレン基としては、具体的には、－ＣＨ２ＣＨ２－、－ＣＨ２ＣＨ２ＣＨ２－、及び－ＣＨ（ＣＨ３）ＣＨ２－が挙げられる。
　オーバーコート液の保存安定性がより良好であるとの観点から、Ａは、－ＣＨ２ＣＨ２－であることが好ましい。 The water-insoluble resin may have only one type represented by the formula (1), or may have two or more types.
A in Formula (1) represents an alkylene group having 2 or 3 carbon atoms.
Specific examples of the alkylene group having 2 or 3 carbon atoms include —CH 2 CH 2 —, —CH 2 CH 2 CH 2 —, and —CH (CH 3 ) CH 2 —.
From the viewpoint that the storage stability of the overcoat solution is better, A is preferably —CH 2 CH 2 —.
　Ａで表される炭素数２又は３のアルキレン基は、式（１）中に１種のみでもよいし、２種以上含まれていてもよい。Ａが２種以上存在する場合には、ｍは、２種以上含まれる－（ＡＯ）－で表される繰り返し単位の総和を表す。例えば、式（１）で表される基が－（ＣＨ２ＣＨ２Ｏ）２－［ＣＨ（ＣＨ３）ＣＨ２Ｏ］２－（ＣＨ２ＣＨ２Ｏ）２－ＣＨ３である場合、ｍは６である。 The alkylene group having 2 or 3 carbon atoms represented by A may be only one kind in the formula (1), or may be contained in two or more kinds. When two or more types of A are present, m represents the total sum of repeating units represented by — (AO) — contained in two or more types. For example, when the group represented by the formula (1) is — (CH 2 CH 2 O) 2 — [CH (CH 3 ) CH 2 O] 2 — (CH 2 CH 2 O) 2 —CH 3 , m Is 6.
　式（１）におけるＲは、水素原子又は炭素数１～２０の炭化水素基を表す。
　炭素数１～２０の炭化水素基としては、直鎖、分岐、又は環状の炭素数１～２０のアルキル基（メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ドデシル基、シクロペンチル基、シクロヘキシル基、２－シクロヘキシルエチル基、ノルボニル基、アダマンチル基等）、炭素数６～２０のアリール基（フェニル基、ナフチル基、４－ビフェニル基、２－ビフェニル基等）、炭素数７～２０のアラルキル基（ベンジル基、フェネチル基、３－フェニルプロピル基、ナフチルメチル基、２－ナフチルエチル基等）が例示される。
　これらの中でも、炭素数１～２０の炭化水素基としては、炭素数１～１２のアルキル基、炭素数６～１０のアリール基、又は炭素数７～１３のアラルキル基であることが好ましく、炭素数１～４のアルキル基であることがより好ましく、メチル基又はエチル基であることが更に好ましく、メチル基であることが特に好ましい。 R in the formula (1) represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.
Examples of the hydrocarbon group having 1 to 20 carbon atoms include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms (methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, Octyl group, nonyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, 2-cyclohexylethyl group, norbornyl group, adamantyl group, etc.), aryl group having 6 to 20 carbon atoms (phenyl group, naphthyl group, 4-biphenyl) Group, 2-biphenyl group, etc.), and aralkyl groups having 7 to 20 carbon atoms (benzyl group, phenethyl group, 3-phenylpropyl group, naphthylmethyl group, 2-naphthylethyl group, etc.).
Among these, the hydrocarbon group having 1 to 20 carbon atoms is preferably an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 10 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms, It is more preferably an alkyl group of 1 to 4, more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.
　これらの炭化水素基は、置換基を有していてもよい。
　置換基としては、ハロゲン原子（塩素原子、フッ素原子、臭素原子等）、ヒドロキシ基、チオール基、スルホ基、シアノ基、エポキシ基、－ＯＲ１０基、－ＯＣＯＲ１０基、－ＣＯＯＲ１０基、－ＣＯＲ１０基、－Ｎ（Ｒ１０）（Ｒ１１）基、－ＮＨＣＯＮＨＲ１０基、－ＮＨＣＯＯＲ１０基、―Ｓｉ（Ｒ１０）３基、－ＣＯＮＨＲ１０基等が挙げられる。これらの置換基はアルキル基中に複数置換されてもよい。
　Ｒ１０及びＲ１１は、それぞれ独立に、メチル基、エチル基、プロピル基、ブチル基、ヘプチル基、ヘキシル基、オクチル基、デシル基、プロペニル基、ブテニル基、ヘキセニル基、オクテニル基、２－ヒドロキシエチル基、３－クロロプロピル基、２－シアノエチル基、Ｎ，Ｎ－ジメチルアミノエチル基、２－ブロモエチル基、２－（２－メトキシエチル）オキシエチル基、２－メトキシカルボニルエチル基、３－カルボキシエチル基、３－カルボキシプロピル基、ベンジル基等を表す。
　なお、炭素数１～２０の炭化水素基が置換基を有する場合、炭素原子数は、その置換基に含まれる炭素原子の数を含めた総和を表す。 These hydrocarbon groups may have a substituent.
Substituents include halogen atoms (chlorine atoms, fluorine atoms, bromine atoms, etc.), hydroxy groups, thiol groups, sulfo groups, cyano groups, epoxy groups, —OR 10 groups, —OCOR 10 groups, —COOR 10 groups, — COR 10 group, —N (R 10 ) (R 11 ) group, —NHCONHR 10 group, —NHCOOR 10 group, —Si (R 10 ) 3 group, —CONHR 10 group and the like can be mentioned. A plurality of these substituents may be substituted in the alkyl group.
R 10 and R 11 are each independently methyl, ethyl, propyl, butyl, heptyl, hexyl, octyl, decyl, propenyl, butenyl, hexenyl, octenyl, 2-hydroxy Ethyl group, 3-chloropropyl group, 2-cyanoethyl group, N, N-dimethylaminoethyl group, 2-bromoethyl group, 2- (2-methoxyethyl) oxyethyl group, 2-methoxycarbonylethyl group, 3-carboxyethyl Group, 3-carboxypropyl group, benzyl group and the like.
Note that when the hydrocarbon group having 1 to 20 carbon atoms has a substituent, the number of carbon atoms represents the total including the number of carbon atoms contained in the substituent.
　式（１）におけるｍは、３以上４０以下の整数を表す。好ましくは５以上２５以下の整数を表し、より好ましくは６以上２０以下の整数を表す。
　ｍが上記範囲内にあることで、オーバーコート液の保存安定性が良好となり、かつ、オーバーコート液により形成される膜の耐水性が良好となる。 M in Formula (1) represents an integer of 3 to 40. Preferably it represents an integer of 5 or more and 25 or less, more preferably an integer of 6 or more and 20 or less.
When m is in the above range, the storage stability of the overcoat liquid is good, and the water resistance of the film formed from the overcoat liquid is good.
　粒子に含まれる水不溶性樹脂中の、式（１）で表される基の合計含有量は、水不溶性樹脂１ｇ当たり、０．０５ｇ以上０．５０ｇ以下であることが好ましく、０．１０ｇ以上０．４０ｇ以下であることがより好ましく、０．２０ｇ以上０．３０ｇ以下であることが更に好ましい。
　水不溶性樹脂中の式（１）で表される基の合計含有量が、水不溶性樹脂１ｇ当たり、０．０５ｇ以上であると、オーバーコート液の保存安定性がより良好となる。
　水不溶性樹脂中の式（１）で表される基の合計含有量が、水不溶性樹脂１ｇ当たり、０．５０ｇ以下であると、オーバーコート液により形成される膜の耐水性が良好となる。 The total content of the group represented by the formula (1) in the water-insoluble resin contained in the particles is preferably 0.05 g or more and 0.50 g or less, and 0.10 g or more and 0 or less per 1 g of the water-insoluble resin. More preferably, it is not more than .40 g, more preferably not less than 0.20 g and not more than 0.30 g.
When the total content of the group represented by the formula (1) in the water-insoluble resin is 0.05 g or more per 1 g of the water-insoluble resin, the storage stability of the overcoat liquid becomes better.
When the total content of the group represented by the formula (1) in the water-insoluble resin is 0.50 g or less per 1 g of the water-insoluble resin, the water resistance of the film formed by the overcoat liquid becomes good.
　粒子に含まれる水不溶性樹脂は、式（１）で表される基を有し、かつ、カルボキシ基を有さない単量体に由来する構成単位を少なくとも含む重合体である。
　水不溶性樹脂は、式（１）で表される基を有し、かつ、カルボキシ基を有さない単量体に由来する構成単位を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 The water-insoluble resin contained in the particles is a polymer having at least a structural unit derived from a monomer having a group represented by the formula (1) and not having a carboxy group.
The water-insoluble resin may contain only one type of structural unit derived from a monomer having a group represented by the formula (1) and not having a carboxy group, or may contain two or more types. May be.
　粒子に含まれる水不溶性樹脂中の、式（１）で表される基を有する構成単位の含有量は、構成単位の構造によっても適宜選択されるが、水不溶性樹脂１ｇ当たり、０．０５ｇ以上０．５５ｇ以下が好ましく、０．１０ｇ以上０．４５ｇ以下がより好ましく、０．２０ｇ以上０．３５ｇ以下が更に好ましい。
　水不溶性樹脂中の式（１）で表される基を有する構成単位の含有量が、水不溶性樹脂１ｇ当たり、０．０５ｇ以上であると、オーバーコート液の保存安定性がより良好となる。
　水不溶性樹脂中の式（１）で表される基を有する構成単位の含有量が、水不溶性樹脂１ｇ当たり、０．５５ｇ以下であると、オーバーコート液により形成される膜の耐水性が良好となる。 The content of the structural unit having the group represented by the formula (1) in the water-insoluble resin contained in the particles is appropriately selected depending on the structure of the structural unit, but is 0.05 g or more per 1 g of the water-insoluble resin. 0.55 g or less is preferable, 0.10 g or more and 0.45 g or less is more preferable, and 0.20 g or more and 0.35 g or less is still more preferable.
When the content of the structural unit having the group represented by the formula (1) in the water-insoluble resin is 0.05 g or more per 1 g of the water-insoluble resin, the storage stability of the overcoat liquid becomes better.
When the content of the structural unit having the group represented by formula (1) in the water-insoluble resin is 0.55 g or less per 1 g of the water-insoluble resin, the water resistance of the film formed by the overcoat liquid is good. It becomes.
　粒子に含まれる水不溶性樹脂は、下記の式（２）で表される少なくとも１種の構成単位と、下記の式（３）及び下記の式（４）からなる群より選ばれる少なくとも１種の構成単位と、を含むことが好ましい。このような態様によれば、オーバーコート液により形成される膜の耐擦性及び耐水性、並びにオーバーコート液の保存安定性がより良好となる。 The water-insoluble resin contained in the particles is at least one selected from the group consisting of at least one structural unit represented by the following formula (2), the following formula (3), and the following formula (4). And a structural unit. According to such an aspect, the abrasion resistance and water resistance of the film formed from the overcoat liquid, and the storage stability of the overcoat liquid are further improved.
Figure JPOXMLDOC01-appb-C000006
 
Figure JPOXMLDOC01-appb-C000006
 
　式（２）中、Ａは、炭素数２又は３のアルキレン基を表し、Ｒは、水素原子又は炭素数１～２０の炭化水素基を表し、Ｒ１は、水素原子又はメチル基を表し、ｍは、３以上４０以下の整数を表す。 In formula (2), A represents an alkylene group having 2 or 3 carbon atoms, R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R 1 represents a hydrogen atom or a methyl group, m represents an integer of 3 to 40.
　式（２）におけるＡは、式（１）におけるＡと同義である。
　式（２）におけるＲは、式（１）におけるＲと同義である。
　式（２）におけるＲ１は、好ましくはメチル基である。
　式（２）におけるｍは、式（１）におけるｍと同義である。 A in Formula (2) is synonymous with A in Formula (1).
R in Formula (2) has the same meaning as R in Formula (1).
R 1 in formula (2) is preferably a methyl group.
M in the formula (2) has the same meaning as m in the formula (1).
　水不溶性樹脂は、式（２）で表される構成単位を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 The water-insoluble resin may contain only one type of structural unit represented by the formula (2), or may contain two or more types.
　式（３）中、Ｒ２は、水素原子又はメチル基を表し、Ｒ３は、炭素数１～２０の炭化水素基を表す。 In formula (3), R 2 represents a hydrogen atom or a methyl group, and R 3 represents a hydrocarbon group having 1 to 20 carbon atoms.
　式（３）におけるＲ２は、好ましくはメチル基である。
　式（３）におけるＲ３は、炭素数１～２０の炭化水素基を表し、式（１）におけるＲで表される炭素数１～２０の炭化水素基と同義である。 R 2 in Formula (3) is preferably a methyl group.
R 3 in the formula (3) represents a hydrocarbon group having 1 to 20 carbon atoms and is synonymous with the hydrocarbon group having 1 to 20 carbon atoms represented by R in the formula (1).
　水不溶性樹脂は、式（３）で表される構成単位を含む場合、式（３）で表される構成単位を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 When the water-insoluble resin includes the structural unit represented by the formula (3), the water-insoluble resin may include only one type of the structural unit represented by the formula (3), or may include two or more types.
　水不溶性樹脂のより好ましい態様としては、水不溶性樹脂が、式（２）で表される少なくとも１種の構成単位と、式（４）で表される少なくとも１種の構成単位と、を含む態様であり、更に好ましい態様としては、水不溶性樹脂が、式（２）で表される少なくとも１種の構成単位と、式（３）で表される少なくとも１種の構成単位と、式（４）で表される少なくとも１種の構成単位と、を含む態様である。
　式（４）は、スチレン由来の構成単位である。水不溶性樹脂が式（４）で表される少なくとも１種の構成単位を含むことで、水不溶性樹脂の粒子の疎水化が高まる。また、ガラス転移温度が高まるため、例えば、水不溶性樹脂の粒子の熱安定性が良好になる。さらに、水不溶性樹脂の屈折率が高まるため、より良好な光沢性を有する膜を形成することができる。 As a more preferred embodiment of the water-insoluble resin, the water-insoluble resin contains at least one structural unit represented by the formula (2) and at least one structural unit represented by the formula (4). In a more preferred embodiment, the water-insoluble resin comprises at least one structural unit represented by the formula (2), at least one structural unit represented by the formula (3), and the formula (4). And at least one structural unit represented by:
Formula (4) is a structural unit derived from styrene. When the water-insoluble resin contains at least one structural unit represented by the formula (4), the hydrophobicity of the water-insoluble resin particles is increased. Further, since the glass transition temperature is increased, for example, the thermal stability of the water-insoluble resin particles is improved. Furthermore, since the refractive index of the water-insoluble resin is increased, a film having better glossiness can be formed.
　水不溶性樹脂が、式（２）で表される少なくとも１種の構成単位と、式（３）で表される少なくとも１種の構成単位と、式（４）で表される少なくとも１種の構成単位と、を含む場合、水不溶性樹脂中における、式（２）で表される構成単位と、式（３）で表される構成単位と、式（４）で表される構成単位と、の含有比率（式（２）で表される構成単位の含有量／式（３）で表される構成単位の含有量／式（４）で表される構成単位の含有量）は、質量基準で、５～５５／５～７５／２０～８０であることが好ましく、１０～４５／１０～６０／２５～７０であることがより好ましく、２０～３５／１５～４５／３０～６０であることが更に好ましい。 The water-insoluble resin is at least one structural unit represented by the formula (2), at least one structural unit represented by the formula (3), and at least one structural unit represented by the formula (4). And a structural unit represented by the formula (2), a structural unit represented by the formula (3), and a structural unit represented by the formula (4) in the water-insoluble resin. The content ratio (content of structural unit represented by formula (2) / content of structural unit represented by formula (3) / content of structural unit represented by formula (4)) is based on mass. It is preferably 5 to 55/5 to 75/20 to 80, more preferably 10 to 45/10 to 60/25 to 70, and more preferably 20 to 35/15 to 45/30 to 60. Is more preferable.
　粒子に含まれる水不溶性樹脂中の、式（２）で表される構成単位の含有量は、水不溶性樹脂１ｇ当たり、０．０５ｇ以上０．５５ｇ以下が好ましく、０．１０ｇ以上０．４５ｇ以下がより好ましく、０．２０ｇ以上０．３５ｇ以下が更に好ましい。
　水不溶性樹脂中の式（２）で表される構成単位の含有量が、水不溶性樹脂１ｇ当たり、０．０５ｇ以上であると、オーバーコート液の保存安定性がより良好となる。
　水不溶性樹脂中の式（２）で表される構成単位の含有量が、水不溶性樹脂１ｇ当たり、０．５５ｇ以下であると、オーバーコート液により形成される膜の耐水性がより良好となる。 The content of the structural unit represented by the formula (2) in the water-insoluble resin contained in the particles is preferably 0.05 g or more and 0.55 g or less, and 0.10 g or more and 0.45 g or less per 1 g of the water-insoluble resin. Is more preferable, and 0.20 g or more and 0.35 g or less is still more preferable.
When the content of the structural unit represented by the formula (2) in the water-insoluble resin is 0.05 g or more per 1 g of the water-insoluble resin, the storage stability of the overcoat liquid becomes better.
When the content of the structural unit represented by the formula (2) in the water-insoluble resin is 0.55 g or less per 1 g of the water-insoluble resin, the water resistance of the film formed by the overcoat liquid becomes better. .
　水不溶性樹脂が式（３）で表される構成単位を含む場合、粒子に含まれる水不溶性樹脂中の、式（３）で表される構成単位の含有量は、Ｒ３の構造により、任意に選択されるが、例えば、水不溶性樹脂１ｇ当たり、０．０５ｇ以上０．７５ｇ以下が好ましく、０．１０ｇ以上０．６０ｇ以下がより好ましく、０．１５ｇ以上０．４５ｇ以下が更に好ましい。
　粒子に含まれる水不溶性樹脂中の、式（３）で表される構成単位の含有量が、上記の範囲内にあると、オーバーコート液により形成される膜の耐水性がより良好となる。 When the water-insoluble resin contains the structural unit represented by the formula (3), the content of the structural unit represented by the formula (3) in the water-insoluble resin contained in the particles is arbitrary depending on the structure of R 3. However, it is preferably 0.05 g or more and 0.75 g or less, more preferably 0.10 g or more and 0.60 g or less, and still more preferably 0.15 g or more and 0.45 g or less per 1 g of water-insoluble resin.
When the content of the structural unit represented by the formula (3) in the water-insoluble resin contained in the particles is within the above range, the water resistance of the film formed by the overcoat liquid becomes better.
　水不溶性樹脂が式（４）で表される構成単位を含む場合、粒子に含まれる水不溶性樹脂中の、式（４）で表される構成単位の含有量は、水不溶性樹脂１ｇ当たり、０．２０ｇ以上０．８０ｇ以下が好ましく、０．２５ｇ以上０．７０ｇ以下がより好ましく、０．３０ｇ以上０．６０ｇ以下が更に好ましい。
　粒子に含まれる水不溶性樹脂中の、式（４）で表される構成単位の含有量が、上記の範囲内にあると、オーバーコート液により形成される膜の光沢性がより良好となる。 When the water-insoluble resin contains the structural unit represented by the formula (4), the content of the structural unit represented by the formula (4) in the water-insoluble resin contained in the particles is 0 per 1 g of the water-insoluble resin. 20 g or more and 0.80 g or less is preferable, 0.25 g or more and 0.70 g or less is more preferable, and 0.30 g or more and 0.60 g or less is still more preferable.
When the content of the structural unit represented by the formula (4) in the water-insoluble resin contained in the particles is within the above range, the gloss of the film formed by the overcoat liquid becomes better.
　水不溶性樹脂中の、樹脂に含まれる式（１）で表される基の含有量、並びに、式（２）で表される構成単位、式（３）で表される構成単位、及び式（４）で表される構成単位の含有量は、以下の方法により求められる。
　オーバーコート液を、限外濾過フィルターを搭載した試験管（製品名：アミコンウルトラ－１５、分画分子量１００ｋＤａ、メルク社）を用いて遠心分離し、水不溶性樹脂の粒子を回収し、溶剤に完全に溶解させた後、核磁気共鳴分光法（ＮＭＲ法）にて構造を同定する。得られた結果に基づき、樹脂に含まれる式（１）で表される基の含有量、並びに、式（２）で表される構成単位、式（３）で表される構成単位、及び式（４）で表される構成単位の含有量を算出する。 The content of the group represented by the formula (1) contained in the resin in the water-insoluble resin, the structural unit represented by the formula (2), the structural unit represented by the formula (3), and the formula ( The content of the structural unit represented by 4) is determined by the following method.
The overcoat solution is centrifuged using a test tube (product name: Amicon Ultra-15, molecular weight cut off 100 kDa, Merck) equipped with an ultrafiltration filter, and the water-insoluble resin particles are collected and completely dissolved in the solvent. Then, the structure is identified by nuclear magnetic resonance spectroscopy (NMR method). Based on the obtained results, the content of the group represented by the formula (1) contained in the resin, the structural unit represented by the formula (2), the structural unit represented by the formula (3), and the formula The content of the structural unit represented by (4) is calculated.
　粒子に含まれる水不溶性樹脂は、既述の構成単位以外の他の単量体に由来する構成単位を含んでいてもよい。
　他の単量体に由来する構成単位としては、特に制限されず、例えば、α－メチルスチレン、アミド系単量体（アクリルアミド、Ｎ－（２－ヒドロキシエチル）アクリルアミド、Ｎ，Ｎ－ジメチルアクリルアミド、Ｎ，Ｎ－ジエチルアクリルアミド、イソプロピルアクリルアミド、Ｎ－（２－ヒドロキシメチル）アクリルアミド、メタクリルアミド等）、シアン化ビニル系単量体（アクリロニトリル、メタクリロニトリル等）、エチレン系不飽和カルボン酸ヒドロキシアルキルエステル系単量体（β－ヒドロキシエチルアクリレート、β－ヒドロキシエチルメタクリレート等）、ジアルキルアミノアルキル（メタ）アクリルアミドの塩酸塩及び硫酸塩等の３級塩（ジメチルアミノエチル（メタ）アクリルアミド等）、カチオン性単量体（ジアルキルアミノアルキル（メタ）アクリレートのハロゲン化アルキル付加物（塩化メチル付加物等）及びハロゲン化アリール付加物（塩化ベンジル付加物等）などの４級塩、並びに、ジアルキルアミノアルキル（メタ）アクリルアミドのハロゲン化アルキル付加物（塩化メチル付加物等）及びハロゲン化アリール付加物（塩化ベンジル付加物等）などの４級塩）、２官能（メタ）アクリレート（エチレングリコールジメタクリレート、エチレングリコールジメタアクリレート、ジエチレングリコールジメタクリレート、ジエチレングリコールジメタアクリレート等）などに由来する構成単位が挙げられる。
　粒子に含まれる水不溶性樹脂は、他の単量体に由来する構成単位を含む場合、他の単量体に由来する構成単位を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 The water-insoluble resin contained in the particles may contain a constituent unit derived from another monomer other than the constituent units described above.
The structural unit derived from other monomers is not particularly limited, and examples thereof include α-methylstyrene, amide monomers (acrylamide, N- (2-hydroxyethyl) acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, isopropylacrylamide, N- (2-hydroxymethyl) acrylamide, methacrylamide, etc.), vinyl cyanide monomers (acrylonitrile, methacrylonitrile, etc.), ethylenically unsaturated carboxylic acid hydroxyalkyl esters Monomers (β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, etc.), dialkylaminoalkyl (meth) acrylamide hydrochlorides and tertiary salts such as sulfates (dimethylaminoethyl (meth) acrylamide, etc.), cationic Monomer (Dialky Quaternary salts such as halogenated alkyl adducts (methyl chloride adducts, etc.) and aryl halide adducts (benzyl chloride adducts, etc.) of aminoalkyl (meth) acrylates, and halogenation of dialkylaminoalkyl (meth) acrylamides Quaternary salts such as alkyl adducts (methyl chloride adducts, etc.) and halogenated aryl adducts (benzyl chloride adducts, etc.)), bifunctional (meth) acrylates (ethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol di) And other structural units derived from methacrylate, diethylene glycol dimethacrylate, etc.).
When the water-insoluble resin contained in the particle includes a structural unit derived from another monomer, the water-insoluble resin may include only one type of structural unit derived from another monomer, or may include two or more types. Also good.
　粒子に含まれる水不溶性樹脂は、カルボキシ基を有さない。
　粒子に含まれる水不溶性樹脂がカルボキシ基を有していると、後述する前処理液に含まれる凝集化成分である酸と水不溶性樹脂とが反応して粒子が凝集し、結果として光沢の低下を招く。本開示におけるオーバーコート液では、粒子に含まれる水不溶性樹脂がカルボキシ基を有さないため、形成される膜の光沢性が良好となる。
　ここで、「カルボキシ基を有さない」とは、水不溶性樹脂がカルボキシ基を実質的に有さないことを意味する。また、「実質的に有さない」とは、カルボキシ基を有する場合においても、有さない場合と同等の性能を発現することを意味する。具体的には、水不溶性樹脂がカルボキシ基を有する場合であっても、水不溶性樹脂中のカルボキシ基の含有量は、水不溶性樹脂１ｇ当たり、例えば、０．０５ｇ以下であり、好ましくは０．０３ｇ以下であり、より好ましくは０．０１ｇ以下である。 The water-insoluble resin contained in the particles does not have a carboxy group.
If the water-insoluble resin contained in the particles has a carboxy group, the acid, which is an aggregating component contained in the pretreatment liquid described later, reacts with the water-insoluble resin to aggregate the particles, resulting in a decrease in gloss. Invite. In the overcoat liquid in the present disclosure, the water-insoluble resin contained in the particles does not have a carboxy group, so that the gloss of the formed film is good.
Here, “having no carboxy group” means that the water-insoluble resin has substantially no carboxy group. In addition, “substantially does not have” means that even when it has a carboxy group, it exhibits the same performance as when it does not. Specifically, even when the water-insoluble resin has a carboxy group, the content of the carboxy group in the water-insoluble resin is, for example, 0.05 g or less, preferably 0. 03 g or less, more preferably 0.01 g or less.
　水不溶性樹脂のガラス転移温度（Ｔｇ）は、４０℃以上が好ましい。
　水不溶性樹脂のＴｇが４０℃以上であると、形成される樹脂膜の耐熱性が優れる。
　Ｔｇは、形成される樹脂膜の耐熱性が良好に保持され、かつ、良好に成膜することができるとの観点から、４５℃以上１５０℃以下がより好ましく、５０℃以上１３０℃以下が更に好ましく、５５℃以上１１０℃以下が特に好ましい。
　水不溶性樹脂のＴｇは、示差走査熱量計（ＤＳＣ：Differential scanning calorimetry）により測定される値である。示差走査熱量計（ＤＳＣ）としては、例えば、エスアイアイ・ナノテクノロジー社のＥＸＳＴＡＲ６２２０を用いることができる。 The glass transition temperature (Tg) of the water-insoluble resin is preferably 40 ° C. or higher.
When the Tg of the water-insoluble resin is 40 ° C. or higher, the heat resistance of the formed resin film is excellent.
Tg is preferably 45 ° C. or higher and 150 ° C. or lower, more preferably 50 ° C. or higher and 130 ° C. or lower, from the viewpoint that the heat resistance of the resin film to be formed is well maintained and the film can be satisfactorily formed. It is preferably 55 ° C. or higher and 110 ° C. or lower.
The Tg of the water-insoluble resin is a value measured by a differential scanning calorimetry (DSC). As the differential scanning calorimeter (DSC), for example, EXSTAR 6220 manufactured by SII Nanotechnology Inc. can be used.
　水不溶性樹脂の重量平均分子量（Ｍｗ）は、１，０００～１，０００，０００が好ましく、５，０００～５００，０００がより好ましく、１０，０００～３００，０００が更に好ましく、オーバーコート液の粘度の観点から、２０，０００～７０，０００が特に好ましい。 The weight average molecular weight (Mw) of the water-insoluble resin is preferably 1,000 to 1,000,000, more preferably 5,000 to 500,000, still more preferably 10,000 to 300,000, From the viewpoint of viscosity, 20,000 to 70,000 is particularly preferable.
　水不溶性樹脂の重量平均分子量は、ゲル透過クロマトグラフ（ＧＰＣ：Gel Permeation Chromatography）により測定される値である。
　具体的には、ＧＰＣは、測定装置として、ＨＬＣ－８２２０ＧＰＣ（東ソー（株））を用い、カラムとして、ＴＳＫｇｅｌ、Ｓｕｐｅｒ　Ｍｕｌｔｉｐｏｒｅ　ＨＺ－Ｈ（４．６ｍｍＩＤ×１５ｃｍ、東ソー（株））を３本用い、溶離液として、ＴＨＦ（テトラヒドロフラン）を用いて行う。また、測定条件としては、試料濃度を０．４５質量％、流速を０．３５ｍｌ／ｍｉｎ、サンプル注入量を１０μｌ、及び測定温度を４０℃として、示唆屈折計（ＲＩ）検出器を用いる。また、検量線は、東ソー（株）の「標準試料ＴＳＫ　ｓｔａｎｄａｒｄ，ｐｏｌｙｓｔｙｒｅｎｅ」：「Ｆ－４０」、「Ｆ－２０」、「Ｆ－４」、「Ｆ－１」、「Ａ－５０００」、「Ａ－２５００」、「Ａ－１０００」、及び「ｎ－プロピルベンゼン」の８サンプルから作製する。 The weight average molecular weight of the water-insoluble resin is a value measured by gel permeation chromatography (GPC).
Specifically, GPC uses HLC-8220GPC (Tosoh Corp.) as a measuring device, and three columns of TSKgel, Super Multipore HZ-H (4.6 mm ID × 15 cm, Tosoh Corp.) as columns. , Using eluent THF (tetrahydrofuran) as an eluent. As the measurement conditions, a suggested refractometer (RI) detector is used with a sample concentration of 0.45 mass%, a flow rate of 0.35 ml / min, a sample injection amount of 10 μl, and a measurement temperature of 40 ° C. In addition, the calibration curve is “standard sample TSK standard, polystyrene” of Tosoh Corporation: “F-40”, “F-20”, “F-4”, “F-1”, “A-5000” Prepared from 8 samples of “A-2500”, “A-1000”, and “n-propylbenzene”.
－粒子中の界面活性剤－
　水不溶性樹脂の粒子は、式（１）で表される基を有するノニオン性界面活性剤を含むこと、即ち、粒子の表面の少なくとも一部に、式（１）で表される基を有するノニオン性界面活性剤を有することが好ましい。この態様では、粒子は、少なくとも、粒子状の水不溶性樹脂と、式（１）で表される基を有するノニオン性界面活性剤と、を含む。
　ここで、「式（１）で表される基を有するノニオン性界面活性剤を含む」には、式（１）で表される基を有するノニオン性界面活性剤が水不溶性樹脂の表面を被覆する態様、及び水不溶性樹脂中に式（１）で表される基を有するノニオン性界面活性剤が含まれる態様が包含される。 -Surfactant in particles-
The particle of the water-insoluble resin contains a nonionic surfactant having a group represented by the formula (1), that is, a nonion having a group represented by the formula (1) on at least a part of the surface of the particle. It is preferable to have a surfactant. In this embodiment, the particles include at least a particulate water-insoluble resin and a nonionic surfactant having a group represented by the formula (1).
Here, “including a nonionic surfactant having a group represented by the formula (1)” covers the surface of the water-insoluble resin with the nonionic surfactant having a group represented by the formula (1). And a mode in which a nonionic surfactant having a group represented by the formula (1) is contained in the water-insoluble resin.
　粒子が有する式（１）で表される基を有するノニオン性界面活性剤と、液中に導入された式（１）で表される基を有するノニオン性界面活性剤と、の区別は、後述するように、遠心分離によりオーバーコート液から粒子を抽出する際、粒子と式（１）で表される基を有するノニオン性界面活性剤とが別の相から取り出されるか、又は粒子と式（１）で表される基を有するノニオン性界面活性剤とが同一の相中から同時に取り出されるかによって判断される。 The distinction between a nonionic surfactant having a group represented by the formula (1) and a nonionic surfactant having a group represented by the formula (1) introduced into the liquid is described later. Thus, when the particles are extracted from the overcoat solution by centrifugation, the particles and the nonionic surfactant having the group represented by the formula (1) are taken out from another phase, or the particles and the formula ( This is determined by whether the nonionic surfactant having the group represented by 1) is simultaneously taken out from the same phase.
　ノニオン性界面活性剤は、式（１）で表される基を少なくとも有するものであれば、従来公知のものを制限なく用いることができる。
　式（１）で表される基を有するノニオン性界面活性剤としては、例えば、分子内に疎水性基とエチレンオキシド及び／又はプロピレンオキシドとの組合せを有する化合物が挙げられる。具体的には、アルキル（炭素数：６～４０）フェノール－エチレンオキシド縮合物、脂肪族（炭素数：６～４０）第一又は第二の線状又は分枝鎖アルコールとエチレンオキシドとの縮合生成物等が挙げられ、Ｒ－Ｏ－（ＣＨ２ＣＨ２Ｏ）ｎ－Ｈ（Ｒ及びｎは、式（１）におけるＲ及びｎと同義である。）の構造で表されるものが好ましい。 As the nonionic surfactant, any conventionally known surfactant can be used without limitation as long as it has at least the group represented by the formula (1).
Examples of the nonionic surfactant having a group represented by the formula (1) include compounds having a combination of a hydrophobic group and ethylene oxide and / or propylene oxide in the molecule. Specifically, alkyl (carbon number: 6 to 40) phenol-ethylene oxide condensate, aliphatic (carbon number: 6 to 40) first or second linear or branched alcohol and condensation product of ethylene oxide And those represented by the structure of R—O— (CH 2 CH 2 O) n—H (R and n are the same as R and n in formula (1)) are preferable.
　式（１）で表される基を有するノニオン性界面活性剤としては、上市されている市販品を用いることができる。
　式（１）で表される基を有するノニオン性界面活性剤の市販品の例としては、花王（株）のエマルゲン（登録商標）シリーズ、日本乳化剤（株）のニューコール（登録商標）シリーズ、第一工業製薬（株）のノイゲン（登録商標）シリーズ、（株）ＡＤＥＫＡのアデカトール（登録商標）シリーズ、三洋化成工業（株）のニューポール（登録商標）シリーズ、エレミノール（登録商標）シリーズ、サンノニック（登録商標）シリーズ、エマルミン（登録商標）シリーズ、ライオン（株）のレオックス（登録商標）シリーズ、レオコール（登録商標）シリーズ、ライオノール（登録商標）シリーズ等が挙げられる。 As the nonionic surfactant having a group represented by the formula (1), commercially available products can be used.
Examples of commercially available nonionic surfactants having a group represented by the formula (1) include Kao's Emulgen (registered trademark) series, Nippon Emulsifier's New Coal (registered trademark) series, Neugen (registered trademark) series of Daiichi Kogyo Seiyaku Co., Ltd., Adekator (registered trademark) series of ADEKA Corporation, New Pole (registered trademark) series, Sanyo Chemical Co., Ltd. (Registered Trademark) Series, Emarumin (Registered Trademark) Series, Lion Corporation's Leox (Registered Trademark) Series, Leocoal (Registered Trademark) Series, Lionol (Registered Trademark) Series, and the like.
　粒子に含まれるノニオン性界面活性剤中の、式（１）で表される基の合計含有量は、粒子を形成する水不溶性樹脂１ｇ当たり、０．０５ｇ以上０．５０ｇ以下であることが好ましく、０．１０ｇ以上０．４０ｇ以下であることがより好ましく、０．２０ｇ以上０．３０ｇ以下であることが更に好ましい。
　ノニオン性界面活性剤中の式（１）で表される基の合計含有量が、粒子を形成する水不溶性樹脂１ｇ当たり、０．０５ｇ以上であると、オーバーコート液の保存安定性がより良好となる。
　ノニオン性界面活性剤中の式（１）で表される基の合計含有量が、水不溶性樹脂１ｇ当たり、０．５０ｇ以下であると、オーバーコート液により形成される膜の耐水性が良好となる。 The total content of the group represented by the formula (1) in the nonionic surfactant contained in the particles is preferably 0.05 g or more and 0.50 g or less per 1 g of the water-insoluble resin forming the particles. 0.10 g or more and 0.40 g or less, more preferably 0.20 g or more and 0.30 g or less.
When the total content of the group represented by the formula (1) in the nonionic surfactant is 0.05 g or more per 1 g of the water-insoluble resin forming the particles, the storage stability of the overcoat liquid is better. It becomes.
When the total content of the group represented by the formula (1) in the nonionic surfactant is 0.50 g or less per 1 g of the water-insoluble resin, the water resistance of the film formed by the overcoat liquid is good. Become.
　粒子に含まれるノニオン性界面活性剤中の式（１）で表される基の含有量は、以下の方法により求められる。
　オーバーコート液を、限外濾過フィルターを搭載した試験管（製品名：アミコンウルトラ－１５、分画分子量１００ｋＤａ、メルク社）を用いて遠心分離し、水不溶性樹脂の粒子を回収し、溶剤に完全に溶解させた後、核磁気共鳴分光法（ＮＭＲ法）にて構造を同定する。得られた結果に基づき、粒子に含まれるノニオン性界面活性剤中の式（１）で表される基の含有量を算出する。 The content of the group represented by the formula (1) in the nonionic surfactant contained in the particles is determined by the following method.
The overcoat solution is centrifuged using a test tube (product name: Amicon Ultra-15, molecular weight cut off 100 kDa, Merck) equipped with an ultrafiltration filter, and the water-insoluble resin particles are collected and completely dissolved in the solvent. Then, the structure is identified by nuclear magnetic resonance spectroscopy (NMR method). Based on the obtained results, the content of the group represented by the formula (1) in the nonionic surfactant contained in the particles is calculated.
　水不溶性樹脂の粒子は、粒子が水性媒体中に分散された分散物（所謂、ラテックスと称される水性分散物）の形態で用いられてもよい。 The water-insoluble resin particles may be used in the form of a dispersion in which the particles are dispersed in an aqueous medium (so-called aqueous dispersion called latex).
　水不溶性樹脂の粒子が水性媒体中に分散された分散物は、従来公知の方法により作製することができる。作製方法としては、例えば、下記に示す方法Ａ及び方法Ｂが挙げられる。
　方法Ａ：疎水性の重合体を水混和性の有機溶剤（アセトン、メタノール等）に溶解させた後、式（１）で表される基を有するノニオン性の界面活性剤を含む水に添加し、撹拌して乳化状態とする。次いで、加熱及び／又は減圧し、有機溶剤を留去することにより、式（１）で表される基を有するノニオン性の界面活性剤で分散された、水不溶性樹脂の粒子の水性分散物を得る方法（所謂、転相乳化方法）。
　方法Ｂ：式（１）で表される基を有するノニオン性の界面活性剤を含む水中に、疎水性の重合性モノマーと熱重合開始剤とを添加し、撹拌して乳化状態とする。次いで、ミセル中で熱により重合を開始させて、水不溶性樹脂の粒子の水性分散物を得る方法（所謂、乳化重合方法）。 A dispersion in which water-insoluble resin particles are dispersed in an aqueous medium can be prepared by a conventionally known method. Examples of the production method include Method A and Method B shown below.
Method A: A hydrophobic polymer is dissolved in a water-miscible organic solvent (acetone, methanol, etc.), and then added to water containing a nonionic surfactant having a group represented by the formula (1). The mixture is stirred to obtain an emulsified state. Next, the aqueous dispersion of water-insoluble resin particles dispersed with a nonionic surfactant having a group represented by the formula (1) is obtained by heating and / or reducing pressure and distilling off the organic solvent. Method to obtain (so-called phase inversion emulsification method).
Method B: A hydrophobic polymerizable monomer and a thermal polymerization initiator are added to water containing a nonionic surfactant having a group represented by the formula (1), and stirred to obtain an emulsified state. Next, polymerization is initiated in micelles by heat to obtain an aqueous dispersion of water-insoluble resin particles (so-called emulsion polymerization method).
　水不溶性樹脂の粒子の水性分散物は、オーバーコート液により形成される膜の耐擦性及び耐水性、並びにオーバーコート液の保存安定性の観点から、方法Ｂにより作製することが好ましい。 The aqueous dispersion of water-insoluble resin particles is preferably prepared by Method B from the viewpoint of the abrasion resistance and water resistance of the film formed by the overcoat liquid and the storage stability of the overcoat liquid.
　水不溶性樹脂の粒子の平均粒子径は、体積平均粒子径で１０ｎｍ～５００ｎｍが好ましく、２０ｎｍ～４００ｎｍがより好ましく、３０ｎｍ～３００ｎｍが更に好ましい。
　水不溶性樹脂の粒子の体積平均粒子径が１０ｎｍ以上であると、製造適性が向上する。
　水不溶性樹脂の粒子の体積平均粒子径が５００ｎｍ以下であると、保存安定性がより向上する。
　水不溶性樹脂の粒子の粒径分布に関しては、特に制限はなく、広い粒径分布又は単分散性の粒径分布のいずれであってもよい。また、単分散性の粒径分布を持つ水不溶性樹脂の粒子を２種以上混合して使用してもよい。
　なお、水不溶性樹脂の粒子の平均粒子径及び粒径分布は、ナノトラック粒度分布測定装置を用いて、動的光散乱法により体積平均粒径を測定することで求められるものである。ナノトラック粒度分布測定装置としては、例えば、日機装（株）のＵＰＡ－ＥＸ１５０を用いることができる。 The average particle size of the water-insoluble resin particles is preferably 10 nm to 500 nm, more preferably 20 nm to 400 nm, and still more preferably 30 nm to 300 nm in terms of volume average particle size.
When the volume average particle diameter of the water-insoluble resin particles is 10 nm or more, the production suitability is improved.
When the volume average particle diameter of the water-insoluble resin particles is 500 nm or less, the storage stability is further improved.
The particle size distribution of the water-insoluble resin particles is not particularly limited, and may be either a wide particle size distribution or a monodisperse particle size distribution. Further, two or more kinds of water-insoluble resin particles having a monodisperse particle size distribution may be mixed and used.
The average particle size and particle size distribution of the water-insoluble resin particles are determined by measuring the volume average particle size by a dynamic light scattering method using a nanotrack particle size distribution measuring device. As the nanotrack particle size distribution measuring apparatus, for example, UPA-EX150 manufactured by Nikkiso Co., Ltd. can be used.
　オーバーコート液は、水不溶性樹脂の粒子を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 The overcoat liquid may contain only one kind of water-insoluble resin particles, or may contain two or more kinds.
　オーバーコート液中における樹脂の粒子の含有量は、特に制限されず、オーバーコート液の全質量に対して、１０質量％～５０質量％が好ましく、１５質量％～４５質量％がより好ましく、２０質量％～４０質量％が更に好ましい。
　オーバーコート液中における樹脂の粒子の含有量が、１０質量％以上であると、オーバーコート液により形成される膜の光沢がより良好となる。
　オーバーコート液中における樹脂の粒子の含有量が、５０質量％以下であると、オーバーコート液の保存安定性がより良好となる。 The content of the resin particles in the overcoat liquid is not particularly limited, and is preferably 10% by mass to 50% by mass, more preferably 15% by mass to 45% by mass with respect to the total mass of the overcoat liquid, 20 More preferred is from 40% by weight.
When the content of the resin particles in the overcoat liquid is 10% by mass or more, the gloss of the film formed by the overcoat liquid becomes better.
When the content of the resin particles in the overcoat liquid is 50% by mass or less, the storage stability of the overcoat liquid becomes better.
（水）
　オーバーコート液は、水を含む。
　オーバーコート液は、水を主溶媒として含む水系の液体である。
　ここで、「水が主溶媒である」とは、オーバーコート液に含まれる全溶媒の合計質量に対する水の含有量が５０質量％を超えていることを指す。 (water)
The overcoat liquid contains water.
The overcoat liquid is an aqueous liquid containing water as a main solvent.
Here, “water is the main solvent” means that the content of water exceeds 50% by mass with respect to the total mass of all solvents contained in the overcoat solution.
　水としては、イオン交換水等を用いることができる。
　オーバーコート液中における水の含有量は、特に制限されず、オーバーコート液の全質量に対して、２０質量％～８０質量％が好ましく、３０質量％～７０質量％がより好ましい。 As water, ion-exchanged water or the like can be used.
The content of water in the overcoat liquid is not particularly limited, and is preferably 20% by mass to 80% by mass, and more preferably 30% by mass to 70% by mass with respect to the total mass of the overcoat liquid.
（他の成分）
　オーバーコート液は、上記の成分以外の他の成分を含んでいてもよい。他の成分としては、例えば、有機溶剤、界面活性剤、ワックス等が挙げられる。
　また、オーバーコート液により形成される膜の光沢を制御する目的で、既述の樹脂の粒子と相溶しないビーズ粒子を含んでいてもよい。 (Other ingredients)
The overcoat liquid may contain components other than the above components. Examples of other components include organic solvents, surfactants, and waxes.
Further, for the purpose of controlling the gloss of the film formed by the overcoat liquid, bead particles that are incompatible with the resin particles described above may be included.
－有機溶剤－
　有機溶剤としては、アルコール（メタノール、エタノール、プロパノール、イソプロパノール（ＩＰＡ）、ブタノール、イソブタノール、ｓｅｃ－ブタノール、ｔ－ブタノール、ペンタノール、ヘキサノール、シクロヘキサノール、ベンジルアルコール等）、多価アルコール（エチレングリコール、ジエチレングリコール、トリエチレングリコール、ポリエチレングリコール、プロピレングリコール、ジプロピレングリコール、ポリプロピレングリコール、ブチレングリコール、ヘキサンジオール、ペンタンジオール、グリセリン、ヘキサントリオール、チオジグリコール等）、グリコール誘導体（エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、エチレングリコールモノブチルエーテル、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノブチルエーテル（ブチルカルビトール）、プロピレングリコールモノメチルエーテル、プロピレングリコールモノブチルエーテル、ジプロピレングリコールモノメチルエーテル、トリプロピレングリコールモノメチルエーテル、トリプロピレングリコールモノエチルエーテル、トリエチレングリコールモノメチルエーテル、エチレングリコールジアセテート、エチレングリコールモノメチルエーテルアセテート、トリエチレングリコールモノメチルエーテル、トリエチレングリコールモノエチルエーテル、エチレングリコールモノフェニルエーテル等）、アミン（エタノールアミン、ジエタノールアミン、トリエタノールアミン、Ｎ－メチルジエタノールアミン、Ｎ－エチルジエタノールアミン、モルホリン、Ｎ－エチルモルホリン、エチレンジアミン、ジエチレントリアミン、トリエチレンテトラミン、ポリエチレンイミン、テトラメチルプロピレンジアミン等）、その他の極性溶剤（ホルムアミド、Ｎ，Ｎ－ジメチルホルムアミド、Ｎ，Ｎ－ジメチルアセトアミド、ジメチルスルホキシド、スルホラン、２－ピロリドン、Ｎ－メチル－２－ピロリドン、Ｎ－ビニル－２－ピロリドン、２－オキサゾリドン、１，３－ジメチル－２－イミダゾリジノン、アセトニトリル、アセトン等）などが挙げられる。
　オーバーコート液は、有機溶剤を含む場合、有機溶剤を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 -Organic solvent-
Organic solvents include alcohol (methanol, ethanol, propanol, isopropanol (IPA), butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.), polyhydric alcohol (ethylene glycol) , Diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), glycol derivatives (ethylene glycol monomethyl ether, ethylene glycol) Monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol Monomethyl ether, diethylene glycol monobutyl ether (butyl carbitol), propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, triethylene glycol monomethyl ether, ethylene Glycol diacetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl ether, etc.), amine (ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyl) Jietanau Amine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine, etc., other polar solvents (formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide Sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone and the like.
When the overcoat liquid contains an organic solvent, the overcoat liquid may contain only one kind of organic solvent, or may contain two or more kinds.
－界面活性剤－
　オーバーコート液は、界面活性剤を含んでいてもよい。
　界面活性剤としては、ノニオン性界面活性剤、カチオン性界面活性剤、アニオン性界面活性剤、ベタイン界面活性剤等が挙げられ、アニオン性界面活性剤が好ましい。
　アニオン性界面活性剤としては、公知のものから適宜選択することができ、例えば、硫酸エステル塩、スルホン酸塩、リン酸塩、脂肪酸塩、ホルマリン縮合物等が挙げられる。
　塩を形成するカチオンとしては、アンモニウムイオン、トリエタノールアミンイオン、金属カチオン等が挙げられる。
　これらの中でも、塩を形成するカチオンとしては、１価の金属カチオンが好ましく、ナトリウムイオン又はカリウムイオンが特に好ましい。 -Surfactant-
The overcoat liquid may contain a surfactant.
Examples of the surfactant include nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants, and the like, and anionic surfactants are preferable.
As an anionic surfactant, it can select from a well-known thing suitably, For example, a sulfate ester salt, a sulfonate, a phosphate, a fatty acid salt, a formalin condensate etc. are mentioned.
Examples of cations that form salts include ammonium ions, triethanolamine ions, metal cations, and the like.
Among these, as the cation forming the salt, a monovalent metal cation is preferable, and sodium ion or potassium ion is particularly preferable.
　アニオン性界面活性剤は、ベタ画像部の濃度低下の抑制及び筋ムラの抑制の効果がより優れるとの観点から、スルホン酸塩及び硫酸エステル塩から選ばれる少なくとも１種を含むことが好ましい。
　アニオン性界面活性剤の中でも、被記録材料の表面の濡れ性を改善する効果が発現しやすいとの観点から、ラウリル硫酸ナトリウム、直鎖ドデシルベンゼンスルホン酸ナトリウム、分岐ドデシルベンゼンスルホン酸ナトリウム、又はスルホコハク酸-ジ-２-エチルヘキシルナトリウムが好ましい。 The anionic surfactant preferably contains at least one selected from a sulfonate salt and a sulfate ester salt from the viewpoint that the effect of suppressing the decrease in the density of the solid image portion and the effect of suppressing the stripe unevenness are more excellent.
Among the anionic surfactants, sodium lauryl sulfate, linear sodium dodecylbenzene sulfonate, branched sodium dodecylbenzene sulfonate, or sulfosuccinic acid is preferable because the effect of improving the wettability of the surface of the recording material is easily exhibited. Acid-di-2-ethylhexyl sodium is preferred.
　オーバーコート液が界面活性剤を含む場合、オーバーコート液中における界面活性剤の含有量は、塗布後の膜を均一にして光沢を高める観点から、オーバーコート液（２５℃）の表面張力を２０ｍＮ／ｍ以上４０ｍＮ／ｍ以下に調整できる量であることが好ましく、２５ｍＮ／ｍ～３５ｍＮ／ｍに調整できる量であることがより好ましい。 When the overcoat liquid contains a surfactant, the content of the surfactant in the overcoat liquid is such that the surface tension of the overcoat liquid (25 ° C.) is 20 mN from the viewpoint of making the coated film uniform and improving the gloss. It is preferably an amount that can be adjusted to 40 mN / m or less, more preferably an amount that can be adjusted to 25 mN / m to 35 mN / m.
－ワックス－
　オーバーコート液は、ワックスを含んでいてもよい。
　ここで、「ワックス」とは、融点が１７０℃以下である高分子化合物を意味し、「ワックス粒子」とは、上記のワックスから形成された粒子を意味する。この点において、ワックスは、融点を有しない又は融点が１７０℃を超える高分子化合物である「樹脂」とは区別されるものであり、ワックス粒子は「樹脂の粒子」とは区別される。
　融点は、示差走査熱量計（ＤＳＣ：Differential scanning calorimetry）を用いたＤＳＣ測定における吸熱ピークトップの温度を意味する。示差走査熱量計（ＤＳＣ）としては、例えば、（株）日立ハイテクサイエンスのＥＸＳＴＡＲ６２２０を用いることができる。 -wax-
The overcoat liquid may contain a wax.
Here, “wax” means a polymer compound having a melting point of 170 ° C. or less, and “wax particles” means particles formed from the above wax. In this respect, the wax is distinguished from “resin” which is a polymer compound having no melting point or a melting point exceeding 170 ° C., and wax particles are distinguished from “resin particles”.
Melting | fusing point means the temperature of the endothermic peak top in DSC measurement using a differential scanning calorimeter (DSC: Differential scanning calorimetry). As the differential scanning calorimeter (DSC), for example, EXSTAR 6220 of Hitachi High-Tech Science Co., Ltd. can be used.
　ワックスは、分散安定性の観点から、粒子の形態で含まれていることが好ましい。すなわち、ワックスは、ワックス粒子の形態で含まれていることが好ましい。
　オーバーコート液がワックスを含む場合、粒子が水性媒体に分散された分散物（所謂、ラテックスと称される水性分散物）の形態で用いられてもよい。 The wax is preferably contained in the form of particles from the viewpoint of dispersion stability. That is, the wax is preferably contained in the form of wax particles.
When the overcoat liquid contains a wax, the particles may be used in the form of a dispersion in which particles are dispersed in an aqueous medium (so-called aqueous dispersion called latex).
　ワックスとしては、例えば、カルナバワックス、キャンデリワックス、みつろう、ライスワックス、ラノリン等の植物系、動物系ワックス、パラフィンワックス、マイクロクリスタリンワックス、ポリオレフィンワックス（ポリエチレンワックス、酸化ポリエチレンワックス等）、ペトロラタム等の石油系ワックス、モンタンワックス、オゾケライト等の鉱物系ワックス、カーボンワックス、ヘキストワックス、ステアリン酸アミド等の合成ワックス、α－オレフィン・無水マレイン酸共重合体などの、天然ワックス若しくは合成ワックス又はこれらの混合物が挙げられる。
　これらの中でも、ワックスとしては、カルナバワックス及びポリオレフィンワックスから選ばれる少なくとも１種が好ましく、画像の耐擦過性の点で、ポリエチレンワックスが特に好ましい。 Examples of waxes include plant systems such as carnauba wax, candelix wax, beeswax, rice wax, lanolin, animal waxes, paraffin wax, microcrystalline wax, polyolefin wax (polyethylene wax, oxidized polyethylene wax, etc.), petrolatum, etc. Natural wax or synthetic wax such as petroleum wax, montan wax, mineral wax such as ozokerite, synthetic wax such as carbon wax, Hoechst wax, stearamide, α-olefin / maleic anhydride copolymer, or a mixture thereof Is mentioned.
Among these, the wax is preferably at least one selected from carnauba wax and polyolefin wax, and polyethylene wax is particularly preferable from the viewpoint of image scratch resistance.
　ワックスは、分散物の形で添加されることが好ましく、例えば、エマルション等の分散物として、オーバーコート液中に含むことができる。分散物とする場合の溶媒としては水が好ましいが、水に限定されるものではなく、例えば、通常用いられている有機溶剤を適宜選択して分散時に使用することができる。有機溶剤については、特開２００６－９１７８０号公報の段落番号［００２７］の記載を参照することができる。 The wax is preferably added in the form of a dispersion, and can be included in the overcoat liquid, for example, as a dispersion such as an emulsion. As a solvent in the case of a dispersion, water is preferable, but it is not limited to water. For example, a commonly used organic solvent can be appropriately selected and used during dispersion. Regarding the organic solvent, reference can be made to the description in paragraph [0027] of JP-A-2006-91780.
　ワックスとしては、上市されている市販品を用いることができる。
　ワックスの市販品の例としては、ノプコートＰＥＭ１７（サンノプコ社）、ケミパール（登録商標）Ｗ４００５（三井化学（株））、ＡＱＵＡＣＥＲ（登録商標）５１５、ＡＱＵＡＣＥＲ（登録商標）５３１、ＡＱＵＡＣＥＲ（登録商標）５９３（以上、ビックケミー・ジャパン（株））、セロゾール５２４（中京油脂（株））等が挙げられる。 A commercially available product can be used as the wax.
Examples of commercially available waxes include Nopcoat PEM17 (San Nopco), Chemipearl (registered trademark) W4005 (Mitsui Chemicals), AQUACER (registered trademark) 515, AQUACER (registered trademark) 531 and AQUACER (registered trademark) 593. (Above, Big Chemie Japan Co., Ltd.), Cellosol 524 (Chukyo Yushi Co., Ltd.), etc.
　オーバーコート液は、ワックスを含む場合、ワックスを１種のみ含んでいてもよいし、２種以上含んでいてもよい。 When the overcoat solution contains a wax, it may contain only one type of wax or two or more types.
－ビーズ粒子－
　オーバーコート液は、ビーズ粒子を含んでいてもよい。
　ビーズ粒子としては、アクリル樹脂ビーズ、アミノ樹脂ビーズ、ポリオレフィン樹脂ビーズ、アルミナビーズ、ガラスビーズ等の粒子が挙げられる。 -Bead particles-
The overcoat liquid may contain bead particles.
Examples of the bead particles include particles such as acrylic resin beads, amino resin beads, polyolefin resin beads, alumina beads, and glass beads.
　アクリル樹脂ビーズとしては、屈折率が１．４０～１．６０であり、かつ、真比重が１．０１～１．５０である、ポリメタクリル酸メチル、ポリメタクリル酸ブチル、ポリメタクリル酸エステル、ポリスチレンと他樹脂（ポリメタクリル酸メチル、ポリメタクリル酸ブチル、ポリメタクリル酸エステル等）との共重合物などが挙げられる。
　アミノ樹脂ビーズとしては、屈折率が１．５０～１．８０であり、かつ、真比重が１．３０～１．８０であるメラミン・ホルムアルデヒド縮合物、ベンゾグアナミン・ホルムアルデヒド縮合物、メラミン・ベンゾグアナミン・ホルムアルデヒド縮合物、及びこれらの縮合物のシリカ処理物等が挙げられる。 As acrylic resin beads, polymethyl methacrylate, polybutyl methacrylate, polymethacrylate, polystyrene having a refractive index of 1.40 to 1.60 and a true specific gravity of 1.01 to 1.50. And other resins (polymethyl methacrylate, polybutyl methacrylate, polymethacrylates, etc.).
Amino resin beads include melamine / formaldehyde condensate, benzoguanamine / formaldehyde condensate, melamine / benzoguanamine / formaldehyde having a refractive index of 1.50 to 1.80 and a true specific gravity of 1.30 to 1.80. Examples include condensates and silica-treated products of these condensates.
　ポリオレフィン樹脂ビーズとしては、屈折率が１．３０～１．６０であり、かつ、真比重が０．９０～１．８０であるポリエチレン樹脂ビーズ、ポリプロピレン樹脂ビーズ等が挙げられる。
　アルミナビーズとしては、屈折率が１．５０～１．９０であり、かつ、真比重が３．８０～４．００である酸化アルミニウムが挙げられる。
　ガラスビーズとしては、屈折率が１．４０～２．３０であり、かつ、真比重が２．４０～４．６０であるソーダ石灰ガラス、チタン－バリウム系ガラス、低アルカリガラス、低アルカリ硼珪酸ガラス等が挙げられる。 Examples of the polyolefin resin beads include polyethylene resin beads and polypropylene resin beads having a refractive index of 1.30 to 1.60 and a true specific gravity of 0.90 to 1.80.
Examples of the alumina beads include aluminum oxide having a refractive index of 1.50 to 1.90 and a true specific gravity of 3.80 to 4.00.
As glass beads, soda-lime glass having a refractive index of 1.40 to 2.30 and a true specific gravity of 2.40 to 4.60, titanium-barium glass, low alkali glass, low alkali borosilicate Glass etc. are mentioned.
　使用するビーズは、既述の式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子と相溶しないことが前提である。オーバーコート液が、既述の式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子と相溶しないビーズ粒子を含むことで、オーバーコート液により形成される膜の光沢を制御することができる。 It is premised that the beads to be used are incompatible with resin particles having a group represented by the above-described formula (1) and not having a carboxy group. The overcoat liquid is formed of the overcoat liquid by including bead particles having a group represented by the above-described formula (1) and not compatible with resin particles not having a carboxy group. The gloss of the film can be controlled.
　オーバーコート液は、ビーズ粒子を含む場合、ビーズ粒子を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 When the overcoat liquid contains bead particles, it may contain only one kind of bead particles or two or more kinds.
　オーバーコート液がビーズ粒子を含む場合、オーバーコート液中におけるビーズ粒子の含有量は、不揮発分換算で、樹脂の粒子の含有量とビーズ粒子の含有量との比率（樹脂の粒子の含有量／ビーズ粒子の含有量）が、２０／１～１／３の範囲であることが好ましく、２／１～１／２の範囲であることがより好ましい。
　オーバーコート液中におけるビーズ粒子の含有量が、上記範囲内であると、オーバーコート液により形成される膜の光沢を所望の光沢に制御することができる。なお、オーバーコート液中におけるビーズ粒子の含有量が、上記範囲を超えると、オーバーコート液により形成される膜の密着性が十分でなくなる傾向がある。 When the overcoat liquid contains bead particles, the content of the bead particles in the overcoat liquid is a ratio of the resin particle content to the bead particle content (resin particle content / The content of the bead particles) is preferably in the range of 20/1 to 1/3, and more preferably in the range of 2/1 to 1/2.
When the content of the bead particles in the overcoat liquid is within the above range, the gloss of the film formed by the overcoat liquid can be controlled to a desired gloss. In addition, when the content of the bead particles in the overcoat liquid exceeds the above range, the adhesion of the film formed by the overcoat liquid tends to be insufficient.
　ビーズ粒子は、屈折率が１．４以上であり、かつ、平均粒子径が０．５μｍ～３０μｍであることが好ましい。
　ビーズ粒子の屈折率と平均粒子径とが、上記範囲内であると、ビーズ粒子が光拡散しなくなり、光沢の制御が容易になる。
　また、ビーズ粒子の平均粒子径が０．５μｍ～３０μｍであると、オーバーコート液により形成される膜の密着性が良好になる。 The bead particles preferably have a refractive index of 1.4 or more and an average particle diameter of 0.5 μm to 30 μm.
When the refractive index and the average particle diameter of the bead particles are within the above range, the bead particles do not diffuse light and the gloss control becomes easy.
In addition, when the average particle diameter of the bead particles is 0.5 μm to 30 μm, the adhesion of the film formed by the overcoat liquid is improved.
～オーバーコート液の物性～
（ｐＨ）
　オーバーコート液のｐＨは、保存安定性の観点から、５．０～１０．０が好ましく、６．０～９．０がより好ましい。
　オーバーコート液のｐＨは、２５℃環境下において、オーバーコート液を２５℃に調温した状態でｐＨメーターを用いて測定される値である。ｐＨメーターとしては、例えば、東亜ディーケーケー（株）のＷＭ－５０ＥＧを用いることができる。 -Physical properties of overcoat liquid-
(PH)
The pH of the overcoat solution is preferably 5.0 to 10.0, more preferably 6.0 to 9.0, from the viewpoint of storage stability.
The pH of the overcoat solution is a value measured using a pH meter in a state where the temperature of the overcoat solution is adjusted to 25 ° C. in an environment of 25 ° C. As the pH meter, for example, WM-50EG manufactured by Toa DK Corporation can be used.
（表面張力）
　オーバーコート液の表面張力としては、特に制限はなく、例えば、２０ｍＮ／ｍ以上とすることができる。塗布後の膜を均一にして光沢を高めるため、また、塗布後の膜の表面滑り性を適切な範囲とするため、２０ｍＮ／ｍ～４０ｍＮ／ｍが好ましく、２５ｍＮ／ｍ～３５ｍＮ／ｍがより好ましい。
　オーバーコート液の表面張力は、表面張力計を用い、プレート法により２５℃の条件下で測定される値である。表面張力計としては、例えば、協和界面科学（株）のＡｕｔｏｍａｔｉｃ　Ｓｕｒｆａｃｅ　Ｔｅｎｓｉｏｍｅｔｅｒ　ＣＢＶＰ－Ｚを用いることができる。
　オーバーコート液の表面張力は、例えば、界面活性剤を添加することで調整することができる。 (surface tension)
There is no restriction | limiting in particular as surface tension of an overcoat liquid, For example, it can be 20 mN / m or more. 20 mN / m to 40 mN / m is preferable, and 25 mN / m to 35 mN / m is more preferable in order to make the film after coating uniform and increase gloss, and to make the surface slipperiness of the film after coating suitable. preferable.
The surface tension of the overcoat liquid is a value measured under a condition of 25 ° C. by a plate method using a surface tension meter. As the surface tension meter, for example, Automatic Surface Tensiometer CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. can be used.
The surface tension of the overcoat liquid can be adjusted, for example, by adding a surfactant.
＜インク組成物＞
　インク組成物は、着色剤及び水を含み、樹脂粒子を含むことが好ましく、必要に応じて、更に他の成分を含んでいてもよい。 <Ink composition>
The ink composition contains a colorant and water, and preferably contains resin particles, and may further contain other components as necessary.
（着色剤）
　インク組成物は、着色剤を含む。
　着色剤としては、特に制限はなく、顔料であってもよいし、染料であってもよい。
　また、着色剤は、後述する前処理液に含まれる凝集化成分（即ち、酸）と接触した際の凝集性に優れるとの観点から、アニオン性着色剤が好ましく、更には顔料が好ましい。
　なお、本開示でいう「アニオン性着色剤」とは、構造中（例えば、着色剤が後述の分散剤で被覆される場合は分散剤の構造中）に、カルボキシ基、スルホ基、リン酸基等のアニオン性基を有する着色剤をいう。 (Coloring agent)
The ink composition includes a colorant.
The colorant is not particularly limited, and may be a pigment or a dye.
The colorant is preferably an anionic colorant, and more preferably a pigment, from the viewpoint of excellent cohesiveness when contacted with an aggregating component (that is, an acid) contained in a pretreatment liquid described later.
As used herein, the term “anionic colorant” refers to a carboxy group, a sulfo group, or a phosphate group in the structure (for example, in the structure of a dispersant when the colorant is coated with a dispersant described later). A colorant having an anionic group such as
－顔料－
　顔料としては、特に制限はなく、目的に応じて適宜選択することができ、例えば、有機顔料又は無機顔料のいずれであってもよい。顔料は、水に殆ど不溶であるか又は難溶であることが、インク着色性の点で好ましい。
　有機顔料としては、アゾレーキ、アゾ顔料、フタロシアニン顔料、ペリレン顔料、ペリノン顔料、アントラキノン顔料、キナクリドン顔料、ジオキサジン顔料、ジケトピロロピロール顔料、チオインジゴ顔料、イソインドリノン顔料、キノフタロン顔料等の多環式顔料；塩基性染料型レーキ、酸性染料型レーキ等の染料レーキ；ニトロ顔料、ニトロソ顔料、アニリンブラック、昼光蛍光顔料等が挙げられる。
　無機顔料としては、酸化チタン、酸化鉄、炭酸カルシウム、硫酸バリウム、水酸化アルミニウム、バリウムイエロー、カドミウムレッド、クロムイエロー、カーボンブラック等が挙げられる。
　また、カラーインデックスに記載されていない顔料であっても、水に分散可能であればいずれも使用できる。更に、顔料を界面活性剤、高分子分散剤等で表面処理したもの、グラフトカーボンなども使用可能である。
　これらの中でも、顔料としては、アゾ顔料、フタロシアニン顔料、アントラキノン顔料、キナクリドン顔料、及びカーボンブラック顔料からなる群より選ばれる少なくとも１種が好ましく、アニオン性のアゾ顔料、アニオン性のフタロシアニン顔料、及びアニオン性のキナクリドン顔料からなる群より選ばれる少なくとも１種がより好ましい。 -Pigment-
There is no restriction | limiting in particular as a pigment, According to the objective, it can select suitably, For example, any of an organic pigment or an inorganic pigment may be sufficient. The pigment is preferably insoluble or hardly soluble in water from the viewpoint of ink colorability.
Organic pigments include polycyclic pigments such as azo lakes, azo pigments, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, diketopyrrolopyrrole pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments. Dye lakes such as basic dye type lakes and acid dye type lakes; nitro pigments, nitroso pigments, aniline black, daylight fluorescent pigments and the like.
Examples of inorganic pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black.
Further, any pigment that is not described in the color index can be used as long as it is dispersible in water. Further, pigments surface-treated with a surfactant, a polymer dispersant, etc., graft carbon, etc. can also be used.
Among these, as the pigment, at least one selected from the group consisting of an azo pigment, a phthalocyanine pigment, an anthraquinone pigment, a quinacridone pigment, and a carbon black pigment is preferable, and an anionic azo pigment, an anionic phthalocyanine pigment, and an anion More preferred is at least one selected from the group consisting of quinacridone pigments.
～分散剤～
　インク組成物では、顔料が分散剤によって分散されている形態が好ましい。中でも、特に顔料がポリマー分散剤によって分散されている形態、即ち、顔料の少なくとも一部がポリマー分散剤により被覆されている形態が好ましい。
　以下、少なくとも一部がポリマー分散剤により被覆されている顔料を「樹脂被覆顔料」という。 ~ Dispersant ~
In the ink composition, a form in which the pigment is dispersed by a dispersant is preferable. In particular, a form in which the pigment is dispersed with the polymer dispersant, that is, a form in which at least a part of the pigment is coated with the polymer dispersant is preferable.
Hereinafter, a pigment at least partially coated with a polymer dispersant is referred to as a “resin-coated pigment”.
　分散剤としては、ポリマー分散剤であってもよいし、低分子の界面活性剤型分散剤であってもよい。また、ポリマー分散剤としては、架橋されていないポリマー分散剤（即ち、非架橋ポリマー分散剤）であってもよいし、架橋剤により架橋されたポリマー分散剤（即ち、架橋ポリマー分散剤）であってもよい。 The dispersant may be a polymer dispersant or a low molecular surfactant type dispersant. The polymer dispersant may be an uncrosslinked polymer dispersant (that is, a non-crosslinked polymer dispersant), or a polymer dispersant that is crosslinked by a crosslinking agent (that is, a crosslinked polymer dispersant). May be.
　非架橋ポリマー分散剤としては、水溶性の非架橋ポリマー分散剤であってもよいし、非水溶性の非架橋ポリマー分散剤であってもよい。
　低分子の界面活性剤型分散剤としては、特開２０１０－１８８６６１号公報の段落［００１６］～［００２０］に記載の界面活性剤型分散剤を用いることができる。 The non-crosslinked polymer dispersant may be a water-soluble non-crosslinked polymer dispersant or a water-insoluble non-crosslinked polymer dispersant.
As the low molecular surfactant type dispersant, the surfactant type dispersants described in paragraphs [0016] to [0020] of JP 2010-188661 A can be used.
　非架橋ポリマー分散剤のうち、水溶性の非架橋ポリマー分散剤としては、親水性高分子化合物を用いることができる。
　水溶性の非架橋ポリマー分散剤としては、例えば、特開２０１０－１８８６６１号公報の段落［００２１］～［００２２］に記載の天然の親水性高分子化合物を用いることができる。 Among the non-crosslinked polymer dispersants, hydrophilic polymer compounds can be used as the water-soluble non-crosslinked polymer dispersant.
As the water-soluble non-crosslinked polymer dispersant, for example, natural hydrophilic polymer compounds described in paragraphs [0021] to [0022] of JP 2010-188661 A can be used.
　また、水溶性の非架橋ポリマー分散剤としては、合成系の親水性高分子化合物を用いることもできる。
　合成系の親水性高分子化合物としては、ポリビニルアルコール、ポリビニルピロリドン、ポリビニルメチルエーテル等のビニル系高分子、ポリアクリルアミド、ポリアクリル酸又はそのアルカリ金属塩、水溶性スチレンアクリル樹脂等のアクリル系樹脂、水溶性スチレンマレイン酸樹脂、水溶性ビニルナフタレンアクリル樹脂、水溶性ビニルナフタレンマレイン酸樹脂、ポリビニルピロリドン、ポリビニルアルコール、β－ナフタレンスルホン酸ホルマリン縮合物のアルカリ金属塩、四級アンモニウム、アミノ基等のカチオン性官能基の塩を側鎖に有する高分子化合物などが挙げられる。 Further, as the water-soluble non-crosslinked polymer dispersant, a synthetic hydrophilic polymer compound can also be used.
Synthetic hydrophilic polymer compounds include vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl methyl ether, polyacrylamide, polyacrylic acid or alkali metal salts thereof, acrylic resins such as water-soluble styrene acrylic resins, Water-soluble styrene maleic acid resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleic resin, polyvinyl pyrrolidone, polyvinyl alcohol, β-naphthalene sulfonic acid formalin condensate alkali metal salt, quaternary ammonium, cation such as amino group And a high molecular compound having a salt of a functional functional group in the side chain.
　これらの中でも、合成系の親水性高分子化合物としては、顔料の分散安定性と凝集性の観点から、カルボキシ基を含む高分子化合物が好ましく、例えば、水溶性スチレンアクリル樹脂等のアクリル系樹脂、水溶性スチレンマレイン酸樹脂、水溶性ビニルナフタレンアクリル樹脂、水溶性ビニルナフタレンマレイン酸樹脂等のようなカルボキシ基を含む高分子化合物が特に好ましい。 Among these, as the synthetic hydrophilic polymer compound, a polymer compound containing a carboxy group is preferable from the viewpoint of dispersion stability and aggregation of the pigment, for example, an acrylic resin such as a water-soluble styrene acrylic resin, High molecular compounds containing a carboxy group such as a water-soluble styrene maleic acid resin, a water-soluble vinyl naphthalene acrylic resin, and a water-soluble vinyl naphthalene maleic resin are particularly preferred.
　非架橋ポリマー分散剤のうち非水溶性分散剤としては、疎水性部及び親水性部の両方を有するポリマーを用いることができる。疎水性部及び親水性部の両方を有するポリマーとしては、スチレン－（メタ）アクリル酸共重合体、スチレン－（メタ）アクリル酸－（メタ）アクリル酸エステル共重合体、（メタ）アクリル酸エステル－（メタ）アクリル酸共重合体、ポリエチレングリコール（メタ）アクリレート－（メタ）アクリル酸共重合体、スチレン－マレイン酸共重合体等が挙げられる。
　スチレン－（メタ）アクリル酸共重合体、（メタ）アクリル酸エステル－（メタ）アクリル酸共重合体、ポリエチレングリコール（メタ）アクリレート－（メタ）アクリル酸共重合体、及びスチレン－マレイン酸共重合体は、２元共重合体であってもよいし、３元以上の共重合体であってもよい。
　これらの中でも、非架橋ポリマー分散剤としては、（メタ）アクリル酸エステル－（メタ）アクリル酸共重合体が好ましく、ベンジル（メタ）アクリレート－（メタ）アクリル酸－メチル（メタ）アクリレート３元共重合体が特に好ましい。
　ここで、（メタ）アクリル酸は、アクリル酸又はメタクリル酸を指し、（メタ）アクリレートは、アクリレート又はメタクリレートを指す。
　なお、共重合体は、ランダム共重合体でもよいし、ブロック共重合体でもよいし、グラフト共重合体でもよい。 Among the non-crosslinked polymer dispersants, a polymer having both a hydrophobic portion and a hydrophilic portion can be used as the water-insoluble dispersant. Examples of the polymer having both a hydrophobic part and a hydrophilic part include a styrene- (meth) acrylic acid copolymer, a styrene- (meth) acrylic acid- (meth) acrylic acid ester copolymer, and a (meth) acrylic acid ester. -(Meth) acrylic acid copolymer, polyethylene glycol (meth) acrylate- (meth) acrylic acid copolymer, styrene-maleic acid copolymer and the like.
Styrene- (meth) acrylic acid copolymer, (meth) acrylic acid ester- (meth) acrylic acid copolymer, polyethylene glycol (meth) acrylate- (meth) acrylic acid copolymer, and styrene-maleic acid copolymer The coalescence may be a binary copolymer or a ternary or higher copolymer.
Among these, as the non-crosslinked polymer dispersant, (meth) acrylic acid ester- (meth) acrylic acid copolymer is preferable, and benzyl (meth) acrylate- (meth) acrylic acid-methyl (meth) acrylate ternary copolymer is preferable. Polymers are particularly preferred.
Here, (meth) acrylic acid refers to acrylic acid or methacrylic acid, and (meth) acrylate refers to acrylate or methacrylate.
The copolymer may be a random copolymer, a block copolymer, or a graft copolymer.
　非架橋ポリマー分散剤の重量平均分子量（Ｍｗ）としては、３，０００～２００，０００が好ましく、より好ましくは５，０００～１００，０００であり、更に好ましくは５，０００～８０，０００であり、特に好ましくは１０，０００～６０，０００である。
　なお、非架橋ポリマー分散剤の重量平均分子量（Ｍｗ）は、既述のオーバーコート液に含まれる水不溶性樹脂の重量平均分子量（Ｍｗ）の測定と同様の方法により測定される値である。 The weight average molecular weight (Mw) of the non-crosslinked polymer dispersant is preferably 3,000 to 200,000, more preferably 5,000 to 100,000, still more preferably 5,000 to 80,000. Particularly preferred is 10,000 to 60,000.
The weight average molecular weight (Mw) of the non-crosslinked polymer dispersant is a value measured by the same method as the measurement of the weight average molecular weight (Mw) of the water-insoluble resin contained in the overcoat liquid described above.
　非架橋ポリマー分散剤の酸価は、特に制限されないが、凝集性の観点からは、後述する樹脂粒子における樹脂（好ましくは、自己分散性樹脂）の酸価よりも大きいことが好ましい。 The acid value of the non-crosslinked polymer dispersant is not particularly limited, but is preferably larger than the acid value of a resin (preferably a self-dispersing resin) in resin particles described later from the viewpoint of cohesiveness.
　架橋ポリマー分散剤は、架橋剤によりポリマー（所謂、未架橋のポリマー）が架橋されることで形成される。
　ポリマーとしては、特に制限されず、種々のポリマーを用いることができるが、中でも、水溶性分散剤として機能し得るポリビニル類、ポリウレタン類、ポリエステル類等が好ましく、ポリビニル類がより好ましい。
　ポリマーは、共重合成分としてカルボキシ基含有モノマーを用いて得られる共重合体であることが好ましい。カルボキシ基含有モノマーとしては、（メタ）アクリル酸、β－カルボキシエチルアクリレート、フマル酸、イタコン酸、マレイン酸、クロトン酸等が挙げられ、中でも、ポリマーの架橋性及び分散安定性の観点から、（メタ）アクリル酸及びβ－カルボキシエチルアクリレートから選ばれる少なくとも１種のモノマーが好ましい。 The crosslinked polymer dispersant is formed by crosslinking a polymer (so-called uncrosslinked polymer) with a crosslinking agent.
The polymer is not particularly limited, and various polymers can be used. Among them, polyvinyls, polyurethanes, polyesters and the like that can function as a water-soluble dispersant are preferable, and polyvinyls are more preferable.
The polymer is preferably a copolymer obtained using a carboxy group-containing monomer as a copolymerization component. Examples of the carboxy group-containing monomer include (meth) acrylic acid, β-carboxyethyl acrylate, fumaric acid, itaconic acid, maleic acid, crotonic acid and the like. Among these, from the viewpoint of the crosslinkability and dispersion stability of the polymer, At least one monomer selected from (meth) acrylic acid and β-carboxyethyl acrylate is preferred.
　ポリマーは、架橋剤により架橋されるため、架橋剤により架橋可能な官能基を有する。架橋可能な官能基としては、特に制限されず、カルボキシ基又はその塩、イソシアネート基、エポキシ基等が挙げられるが、例えば、分散性向上の観点から、カルボキシ基又はその塩が好ましい。 Since the polymer is crosslinked by a crosslinking agent, it has a functional group that can be crosslinked by the crosslinking agent. The crosslinkable functional group is not particularly limited, and examples thereof include a carboxy group or a salt thereof, an isocyanate group, and an epoxy group. For example, a carboxy group or a salt thereof is preferable from the viewpoint of improving dispersibility.
　ポリマーの酸価は、ポリマーの水溶性の観点から、９０ｍｇＫＯＨ／ｇ以上であることが好ましく、９５ｍｇＫＯＨ／ｇ以上であることがより好ましい。
　さらには、顔料の分散性及び分散安定性の観点から、１００ｍｇＫＯＨ／ｇ～１８０ｍｇＫＯＨ／ｇであることが好ましく、１００ｍｇＫＯＨ／ｇ～１７０ｍｇＫＯＨ／ｇであることがより好ましく、１００ｍｇＫＯＨ／ｇ～１６０ｍｇＫＯＨ／ｇであることが更に好ましい。
　なお、ポリマーの酸価は、日本工業規格（ＪＩＳ　Ｋ００７０：１９９２）に記載の方法により測定される値である。 The acid value of the polymer is preferably 90 mgKOH / g or more, and more preferably 95 mgKOH / g or more, from the viewpoint of water solubility of the polymer.
Furthermore, from the viewpoint of the dispersibility and dispersion stability of the pigment, it is preferably 100 mgKOH / g to 180 mgKOH / g, more preferably 100 mgKOH / g to 170 mgKOH / g, and 100 mgKOH / g to 160 mgKOH / g. More preferably it is.
The acid value of the polymer is a value measured by the method described in Japanese Industrial Standard (JIS K0070: 1992).
　ポリマーの重量平均分子量（Ｍｗ）としては、５０，０００～１２０，０００が好ましく、より好ましくは６０，０００～１２０，０００であり、更に好ましくは６０，０００～１００，０００であり、特に好ましくは６０，０００～９０，０００である。
　なお、ポリマーの重量平均分子量（Ｍｗ）は、既述のオーバーコート液に含まれる水不溶性樹脂の重量平均分子量（Ｍｗ）の測定と同様の方法により測定される値である。 The weight average molecular weight (Mw) of the polymer is preferably 50,000 to 120,000, more preferably 60,000 to 120,000, still more preferably 60,000 to 100,000, and particularly preferably 60,000 to 90,000.
In addition, the weight average molecular weight (Mw) of a polymer is a value measured by the method similar to the measurement of the weight average molecular weight (Mw) of the water-insoluble resin contained in the above-mentioned overcoat liquid.
　ポリマーは、更に、疎水性モノマーの少なくとも１種を共重合成分として有していることが好ましい。疎水性モノマーとしては、炭素数が１～２０のアルキル（メタ）アクリレート、ベンジル（メタ）アクリレート、フェノキシエチル（メタ）アクリレート等の芳香環基を有する（メタ）アクリレート、スチレン及びその誘導体などが挙げられる。
　ポリマーの共重合形態は、特に制限されず、ポリマーは、ランダムポリマーでもよいし、ブロックポリマーでもよいし、グラフトポリマーでもよい。 The polymer preferably further has at least one hydrophobic monomer as a copolymerization component. Examples of the hydrophobic monomer include (meth) acrylate having an aromatic ring group such as alkyl (meth) acrylate having 1 to 20 carbon atoms, benzyl (meth) acrylate, and phenoxyethyl (meth) acrylate, styrene and derivatives thereof. It is done.
The copolymerization form of the polymer is not particularly limited, and the polymer may be a random polymer, a block polymer, or a graft polymer.
　ポリマーの合成方法は、特に制限されないが、例えば、ビニルモノマーのランダム重合による合成が、分散安定性の点で好ましい。 The method for synthesizing the polymer is not particularly limited, but for example, synthesis by random polymerization of vinyl monomers is preferable from the viewpoint of dispersion stability.
　架橋剤は、ポリマーと反応する部位を２つ以上有している化合物であれば、特に制限されないが、カルボキシ基との反応性に優れているとの観点から、２つ以上のエポキシ基を有している化合物（即ち、２官能以上のエポキシ化合物）が好ましい。
　架橋剤としては、例えば、エチレングリコールジグリシジルエーテル、ポリエチレングリコールジグリシジルエーテル、１，６－へキサンジオールジグリシジルエーテル、ジエチレングリコールジグリシジルエーテル、ポリエチレングリコールジグリシジルエーテル、ジプロピレングリコールジグリシジルエーテル、ポリプロピレングリコールジグリシジルエーテル、トリメチロールプロパントリグリシジルエーテル等が挙げられる。
　これらの中でも、架橋剤としては、ポリエチレングリコールジグリシジルエーテル、ジエチレングリコールジグリシジルエーテル、及びトリメチロールプロパントリグリシジルエーテルからなる群より選ばれる少なくとも１種が好ましい。 The cross-linking agent is not particularly limited as long as it is a compound having two or more sites that react with the polymer, but has two or more epoxy groups from the viewpoint of excellent reactivity with a carboxy group. (I.e., bifunctional or higher functional epoxy compounds) are preferred.
Examples of the crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, and polypropylene glycol. Examples thereof include diglycidyl ether and trimethylolpropane triglycidyl ether.
Among these, the crosslinking agent is preferably at least one selected from the group consisting of polyethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether.
　顔料に架橋ポリマー分散剤を被覆する方法としては、例えば、顔料を水溶性又は水不溶性のポリマーを用いて分散した後に、架橋剤によりポリマーを架橋する方法が挙げられる。 Examples of the method of coating the pigment with the crosslinked polymer dispersant include a method of dispersing the pigment using a water-soluble or water-insoluble polymer and then crosslinking the polymer with the crosslinking agent.
　インク組成物において、顔料と分散剤との質量比（顔料：分散剤）としては、１：０．０６～１：３の範囲が好ましく、１：０．１２５～１：２の範囲がより好ましく、１：０．１２５～１：１．５が更に好ましい。 In the ink composition, the mass ratio of pigment to dispersant (pigment: dispersant) is preferably in the range of 1: 0.06 to 1: 3, more preferably in the range of 1: 0.125 to 1: 2. 1: 0.125 to 1: 1.5 is more preferable.
　顔料の平均粒子径（顔料が樹脂被覆顔料である場合には、樹脂被覆顔料の平均粒子径。以下、同じ。）としては、１０ｎｍ～２００ｎｍが好ましく、１０ｎｍ～１５０ｎｍがより好ましく、１０ｎｍ～１００ｎｍが更に好ましい。
　平均粒子径が２００ｎｍ以下であると、色再現性が良好となり、かつ、インクジェット法で打滴する際の打滴特性が良好になる。
　平均粒子径が１０ｎｍ以上であると、耐光性が良好になる。
　顔料の粒径分布に関しては、特に制限はなく、広い粒径分布又は単分散性の粒径分布のいずれであってもよい。また、単分散性の粒径分布を持つ顔料を２種以上混合して使用してもよい。
　なお、顔料の平均粒子径及び粒径分布は、ナノトラック粒度分布測定装置を用いて、動的光散乱法により体積平均粒子径を測定することで求められるものである。ナノトラック粒度分布測定装置としては、例えば、日機装（株）のＵＰＡ－ＥＸ１５０を用いることができる。 The average particle diameter of the pigment (when the pigment is a resin-coated pigment, the average particle diameter of the resin-coated pigment; hereinafter the same) is preferably 10 nm to 200 nm, more preferably 10 nm to 150 nm, and more preferably 10 nm to 100 nm. Further preferred.
When the average particle size is 200 nm or less, the color reproducibility is good and the droplet ejection characteristics when droplets are ejected by the ink jet method are good.
When the average particle size is 10 nm or more, light resistance is improved.
The particle size distribution of the pigment is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution. Two or more pigments having a monodispersed particle size distribution may be mixed and used.
In addition, the average particle diameter and particle size distribution of a pigment are calculated | required by measuring a volume average particle diameter with a dynamic light scattering method using a nano track particle size distribution measuring apparatus. As the nanotrack particle size distribution measuring apparatus, for example, UPA-EX150 manufactured by Nikkiso Co., Ltd. can be used.
－染料－
　染料としては、特に制限はなく、公知の染料、例えば、特開２００１－１１５０６６号公報、特開２００１－３３５７１４号公報、特開２００２－２４９６７７号公報等に記載の染料を好適に用いることができる。
　染料を用いる場合には、染料を水不溶性の担体に保持したものを用いてもよい。染料を保持した担体（所謂、水不溶性着色粒子）は、分散剤を用いて水系分散物として用いることができる。担体としては、水に不溶又は水に難溶であれば、特に制限なく、用いることができる。担体としては、無機材料、有機材料及びこれらの複合材料のいずれであってもよい。具体的には、特開２００１－１８１５４９号公報、特開２００７－１６９４１８号公報等に記載の担体を好適に用いることができる。 -dye-
The dye is not particularly limited, and known dyes such as those described in JP-A Nos. 2001-115066, 2001-335714, and 2002-249677 can be suitably used. .
When a dye is used, a dye held on a water-insoluble carrier may be used. The carrier holding the dye (so-called water-insoluble colored particles) can be used as an aqueous dispersion using a dispersant. The carrier can be used without particular limitation as long as it is insoluble in water or hardly soluble in water. The carrier may be any of inorganic materials, organic materials, and composite materials thereof. Specifically, the carriers described in JP-A Nos. 2001-181549 and 2007-169418 can be preferably used.
　インク組成物は、着色剤を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 The ink composition may contain only one colorant or two or more colorants.
　インク組成物中における着色剤（特に、顔料）の含有量は、画像濃度の観点から、インク組成物の全質量に対して、１質量％～２５質量％が好ましく、２質量％～２０質量％がより好ましく、２質量％～１０質量％が特に好ましい。 The content of the colorant (particularly the pigment) in the ink composition is preferably 1% by mass to 25% by mass with respect to the total mass of the ink composition from the viewpoint of image density, and 2% by mass to 20% by mass. Is more preferable, and 2% by mass to 10% by mass is particularly preferable.
（水）
　インク組成物は、水を含み、水性組成物として調製されている。
　水としては、イオン交換水等を用いることができる。
　インク組成物中における水の含有量は、特に制限されず、インク組成物の全質量に対して、１０質量％～９９質量％が好ましく、３０質量％～８０質量％がより好ましく、５０質量％～８０質量％が更に好ましい。 (water)
The ink composition contains water and is prepared as an aqueous composition.
As water, ion-exchanged water or the like can be used.
The content of water in the ink composition is not particularly limited, and is preferably 10% by mass to 99% by mass, more preferably 30% by mass to 80% by mass, and 50% by mass with respect to the total mass of the ink composition. More preferably, it is 80% by mass.
（樹脂粒子）
　インク組成物は、樹脂粒子を含むことが好ましい。
　樹脂粒子は、既述のポリマー分散剤（即ち、顔料の少なくとも一部を覆うポリマー分散剤）とは異なり、顔料とは別に存在している粒子である。
　インク組成物が樹脂粒子を含む場合、樹脂粒子は、後述する前処理液に含まれる凝集化成分（即ち、酸）と接触することで凝集するものであることが好ましい。
　また、樹脂粒子は、後述する前処理液に含まれる凝集化成分と接触した際の凝集性に優れる点から、スルホ基以外のアニオン性の解離基を有する樹脂粒子が好ましい。スルホ基以外のアニオン性の解離基を有する樹脂粒子の詳細は後述する。
　アニオン性解離基としてスルホ基を有する樹脂粒子は、樹脂粒子自体の分散安定性が大きく向上するため、前処理液に含まれる凝集化成分と接触しても凝集し難い点で好ましくない。 (Resin particles)
The ink composition preferably contains resin particles.
Unlike the polymer dispersant described above (that is, the polymer dispersant covering at least a part of the pigment), the resin particles are particles that exist separately from the pigment.
When the ink composition contains resin particles, the resin particles are preferably aggregated by contact with an aggregating component (that is, an acid) contained in a pretreatment liquid described later.
In addition, the resin particles are preferably resin particles having an anionic dissociation group other than a sulfo group from the viewpoint of excellent cohesiveness when contacted with an aggregating component contained in a pretreatment liquid described later. Details of the resin particles having an anionic dissociation group other than the sulfo group will be described later.
Resin particles having a sulfo group as an anionic dissociation group are not preferable in that the dispersion stability of the resin particles themselves is greatly improved, so that they do not easily aggregate even if they come into contact with the aggregating component contained in the pretreatment liquid.
　樹脂粒子は、非水溶性又は難水溶性の樹脂の粒子であることが好ましい。
　ここで、「非水溶性又は難水溶性」であるとは、既述のオーバーコート液の項に記載の定義と同様に、樹脂を１０５℃で２時間乾燥させた後、２５℃の水１００ｇ中に溶解させた場合に、その溶解量が１５ｇ以下であることをいう。インクの連続吐出性及び吐出安定性が向上する観点から、溶解量は、好ましくは１０ｇ以下、より好ましくは５ｇ以下であり、更に好ましくは１ｇ以下である。
　溶解量は、非水溶性又は難水溶性の樹脂の塩生成基の種類に応じて、水酸化ナトリウム又は酢酸で１００％中和した時の溶解量である。 The resin particles are preferably water-insoluble or poorly water-soluble resin particles.
Here, “non-water-soluble or sparingly water-soluble” means that the resin is dried at 105 ° C. for 2 hours and then 100 g of water at 25 ° C. When dissolved in, it means that the dissolved amount is 15 g or less. From the viewpoint of improving the continuous ejection property and ejection stability of the ink, the dissolution amount is preferably 10 g or less, more preferably 5 g or less, and even more preferably 1 g or less.
The dissolution amount is the dissolution amount when 100% neutralized with sodium hydroxide or acetic acid depending on the type of the salt-forming group of the water-insoluble or poorly water-soluble resin.
　樹脂粒子としては、例えば、熱可塑性、熱硬化性、又は変性のアクリル系、エポキシ系、ポリウレタン系、ポリエーテル系、ポリアミド系、不飽和ポリエステル系、フェノール系、シリコーン系、又はフッ素系の樹脂、塩化ビニル、酢酸ビニル、ポリビニルアルコール、又はポリビニルブチラール等のポリビニル系樹脂、アルキド樹脂、フタル酸樹脂等のポリエステル系樹脂、メラミン樹脂、メラミンホルムアルデヒド樹脂、アミノアルキド共縮合樹脂、ユリア樹脂、尿素樹脂等のアミノ系材料、或いはそれらの共重合体又は混合物などのアニオン性基を有する樹脂の粒子が挙げられる。
　これらの樹脂粒子のうち、アニオン性のアクリル系樹脂は、例えば、スルホ基以外のアニオン性の解離性基を有するアクリルモノマー（所謂、アニオン性基含有アクリルモノマー）及び必要に応じてアニオン性の解離性基含有アクリルモノマーと共重合可能な他のモノマーを溶剤中で重合して得られる。
　アニオン性の解離性基含有アクリルモノマーとしては、例えば、カルボキシ基、及びホスホン酸基からなる群より選ばれる１つ以上の基を有するアクリルモノマーが挙げられる。これらの中でも、アニオン性の解離性基含有アクリルモノマーとしては、カルボキシ基を有するアクリルモノマー（アクリル酸、メタクリル酸、クロトン酸、エタアクリル酸、プロピルアクリル酸、イソプロピルアクリル酸、イタコン酸、フマル酸等）が好ましく、アクリル酸及びメタクリル酸の少なくとも一方が特に好ましい。 Examples of the resin particles include thermoplastic, thermosetting, or modified acrylic, epoxy, polyurethane, polyether, polyamide, unsaturated polyester, phenol, silicone, or fluorine resins, Polyvinyl resins such as vinyl chloride, vinyl acetate, polyvinyl alcohol, or polyvinyl butyral, polyester resins such as alkyd resins and phthalic resins, melamine resins, melamine formaldehyde resins, aminoalkyd co-condensation resins, urea resins, urea resins, etc. Examples thereof include resin particles having an anionic group such as an amino material, a copolymer or a mixture thereof.
Among these resin particles, an anionic acrylic resin is, for example, an acrylic monomer having an anionic dissociative group other than a sulfo group (so-called anionic group-containing acrylic monomer) and an anionic dissociation as required. It can be obtained by polymerizing another monomer copolymerizable with a functional group-containing acrylic monomer in a solvent.
Examples of the anionic dissociable group-containing acrylic monomer include an acrylic monomer having one or more groups selected from the group consisting of a carboxy group and a phosphonic acid group. Among these, as an anionic dissociative group-containing acrylic monomer, an acrylic monomer having a carboxy group (acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, fumaric acid, etc. ) Is preferred, and at least one of acrylic acid and methacrylic acid is particularly preferred.
　樹脂粒子としては、インク組成物の吐出安定性及び着色剤を含む系の液安定性（特に、分散安定性）の観点から、自己分散性樹脂の粒子（所謂、自己分散性樹脂粒子）であることが好ましい。
　本開示でいう「自己分散性樹脂」とは、界面活性剤の不存在下、転相乳化法により分散状態とした場合、ポリマー自身が有する官能基（特に酸性基又はその塩の親水性基）によって、水性媒体中で分散状態となり得る水不溶性ポリマーをいう。
　ここで、「分散状態」とは、水性媒体中に水不溶性ポリマーが液体状態で分散された乳化状態（所謂、エマルション）、及び、水性媒体中に水不溶性ポリマーが固体状態で分散された分散状態（所謂、サスペンジョン）の両方の状態を含むものである。
　また、「水性媒体」は、水を含む媒体を指す。水性媒体は、必要に応じて、親水性有機溶剤を含んでいてもよい。水性媒体は、水と水に対して０．２質量％以下の親水性有機溶剤とが含まれることが好ましく、水のみであることがより好ましい。
　自己分散性樹脂としては、インク組成物に含有された場合の凝集速度及び定着性の観点から、水不溶性ポリマーが固体状態で分散された分散状態となりうる自己分散性樹脂粒子であることが好ましい。 The resin particles are self-dispersing resin particles (so-called self-dispersing resin particles) from the viewpoint of ejection stability of the ink composition and liquid stability (particularly dispersion stability) of the system containing the colorant. It is preferable.
The “self-dispersing resin” as used in the present disclosure is a functional group (especially an acidic group or a hydrophilic group of a salt thereof) possessed by the polymer itself when dispersed by the phase inversion emulsification method in the absence of a surfactant. Refers to a water-insoluble polymer that can be dispersed in an aqueous medium.
Here, the “dispersed state” means an emulsified state in which a water-insoluble polymer is dispersed in an aqueous medium (so-called emulsion), and a dispersed state in which the water-insoluble polymer is dispersed in a solid state. It includes both states (so-called suspension).
An “aqueous medium” refers to a medium containing water. The aqueous medium may contain a hydrophilic organic solvent as necessary. The aqueous medium preferably contains water and 0.2% by mass or less of a hydrophilic organic solvent with respect to water, and more preferably contains only water.
The self-dispersing resin is preferably self-dispersing resin particles that can be in a dispersed state in which a water-insoluble polymer is dispersed in a solid state from the viewpoint of aggregation speed and fixing property when contained in the ink composition.
　自己分散性樹脂の乳化状態又は分散状態を得る方法、即ち、自己分散性樹脂粒子の水性分散物の調製方法としては、転相乳化法が挙げられる。
　転相乳化法としては、例えば、自己分散性樹脂を溶媒（例えば、水溶性有機溶剤等）中に溶解又は分散させた後、界面活性剤を添加せずにそのまま水中に投入し、自己分散性樹脂が有する塩生成基（例えば、酸性基）を中和した状態で、撹拌し、混合し、溶媒を除去した後、乳化状態又は分散状態となった水性分散物を得る方法が挙げられる。 Examples of a method for obtaining an emulsified state or a dispersed state of the self-dispersing resin, that is, a method for preparing an aqueous dispersion of self-dispersing resin particles include a phase inversion emulsification method.
As the phase inversion emulsification method, for example, a self-dispersing resin is dissolved or dispersed in a solvent (for example, a water-soluble organic solvent) and then poured into water as it is without adding a surfactant. Examples include a method of obtaining an aqueous dispersion in an emulsified state or a dispersed state after stirring and mixing in a state in which a salt-forming group (for example, acidic group) of the resin is neutralized and mixing, and removing the solvent.
　また、自己分散性樹脂における安定な乳化状態又は分散状態とは、水不溶性ポリマー３０ｇを７０ｇの有機溶剤（例えば、メチルエチルケトン）に溶解した溶液、水不溶性ポリマーの塩生成基を１００％中和できる中和剤（塩生成基がアニオン性の場合は水酸化ナトリウムであり、塩生成基がカチオン性の場合は酢酸である。）、及び水２００ｇを混合し、撹拌（装置：撹拌羽根付き撹拌装置、回転数：２００ｒｐｍ（revolutions per minute；以下、同じ。）、撹拌時間：３０分間、撹拌温度：２５℃）した後、混合液から有機溶剤を除去した後でも、乳化状態又は分散状態が、２５℃で少なくとも１週間安定に存在する状態（即ち、沈殿を目視で確認できない状態）であることをいう。 In addition, a stable emulsified state or dispersed state in the self-dispersing resin is a solution in which 30 g of a water-insoluble polymer is dissolved in 70 g of an organic solvent (for example, methyl ethyl ketone). Mixing agent (sodium hydroxide when the salt-forming group is anionic, acetic acid when the salt-forming group is cationic) and 200 g of water, stirring (apparatus: stirring device with stirring blades, Rotational speed: 200 rpm (revolutions per minute; the same applies hereinafter), stirring time: 30 minutes, stirring temperature: 25 ° C., and even after removing the organic solvent from the mixture, the emulsified state or dispersed state is 25 ° C. In a state that exists stably for at least one week (that is, a state in which precipitation cannot be visually confirmed).
　また、自己分散性樹脂における乳化状態又は分散状態の安定性は、遠心分離による沈降の加速試験によっても確認することができる。遠心分離による、沈降の加速試験による安定性は、例えば、上記の方法により得られた樹脂粒子の水性分散物を、固形分濃度２５質量％に調整した後、１２，０００ｒｐｍで１時間遠心分離し、遠心分離後の上澄みの固形分濃度を測定することによって評価できる。
　遠心分離前の固形分濃度に対する遠心分離後の固形分濃度の比が大きければ（即ち、１に近い数値であれば）、遠心分離による樹脂粒子の沈降が生じない、即ち、樹脂粒子の水性分散物がより安定であることを意味する。遠心分離前後での固形分濃度の比としては、０．８以上が好ましく、０．９以上がより好ましく、０．９５以上が特に好ましい。 The stability of the emulsified state or dispersed state in the self-dispersing resin can also be confirmed by an accelerated sedimentation test by centrifugation. The stability by the accelerated sedimentation test by centrifugation is, for example, that the aqueous dispersion of resin particles obtained by the above method is adjusted to a solid content concentration of 25% by mass and then centrifuged at 12,000 rpm for 1 hour. It can be evaluated by measuring the solid content concentration of the supernatant after centrifugation.
If the ratio of the solid content concentration after centrifugation to the solid content concentration before centrifugation is large (that is, a value close to 1), the resin particles will not settle due to centrifugation, that is, the aqueous dispersion of resin particles. It means that things are more stable. The ratio of the solid content concentration before and after centrifugation is preferably 0.8 or more, more preferably 0.9 or more, and particularly preferably 0.95 or more.
　自己分散性樹脂は、分散状態とした場合に水溶性を示す水溶性成分の含有量が１０質量％以下であることが好ましく、８質量％以下であることがより好ましく、６質量％以下であることが更に好ましい。
　水溶性成分の含有量を１０質量％以下とすることで、樹脂粒子の膨潤及び樹脂粒子同士の融着を効果的に抑制し、より安定な分散状態を維持することができる。また、インク組成物の粘度上昇を抑制でき、例えば、インク組成物をインクジェット法に適用する場合に、吐出安定性がより良好になる。
　ここで、「水溶性成分」とは、自己分散性樹脂に含有される化合物であって、自己分散性樹脂を分散状態にした場合に水に溶解する化合物をいう。水溶性成分は自己分散性樹脂を製造する際に、副生又は混入する水溶性の化合物である。 The self-dispersing resin preferably has a water-soluble component content that exhibits water solubility in a dispersed state of 10% by mass or less, more preferably 8% by mass or less, and 6% by mass or less. More preferably.
By setting the content of the water-soluble component to 10% by mass or less, the swelling of the resin particles and the fusion of the resin particles can be effectively suppressed, and a more stable dispersion state can be maintained. In addition, an increase in the viscosity of the ink composition can be suppressed. For example, when the ink composition is applied to an ink jet method, the ejection stability becomes better.
Here, the “water-soluble component” refers to a compound that is contained in a self-dispersing resin and that dissolves in water when the self-dispersing resin is in a dispersed state. The water-soluble component is a water-soluble compound that is by-produced or mixed when the self-dispersing resin is produced.
　水不溶性ポリマーの主鎖骨格としては、特に制限はなく、ビニルポリマー、縮合系ポリマー（エポキシ樹脂、ポリエステル、ポリウレタン、ポリアミド、セルロース、ポリエーテル、ポリウレア、ポリイミド、ポリカーボネート等）などが挙げられる。
　これらの中でも、水不溶性ポリマーの主鎖骨格としては、ビニルポリマーが特に好ましい。 The main chain skeleton of the water-insoluble polymer is not particularly limited, and examples thereof include vinyl polymers and condensation polymers (epoxy resins, polyesters, polyurethanes, polyamides, celluloses, polyethers, polyureas, polyimides, polycarbonates, etc.).
Among these, a vinyl polymer is particularly preferable as the main chain skeleton of the water-insoluble polymer.
　ビニルポリマー及びビニルポリマーを構成するモノマーの好適な例としては、特開２００１－１８１５４９号公報及び特開２００２－８８２９４号公報に記載されているものを挙げることができる。また、解離性基（又は解離性基に誘導できる置換基）を有する連鎖移動剤、重合開始剤、イニファーターを用いたビニルモノマーのラジカル重合、開始剤或いは停止剤のどちらかに解離性基（又は解離性基に誘導できる置換基）を有する化合物を用いたイオン重合によって、高分子鎖の末端に解離性基を導入したビニルポリマーも使用できる。
　また、縮合系ポリマーと縮合系ポリマーを構成するモノマーの好適な例としては、特開２００１－２４７７８７号公報に記載されているものを挙げることができる。 Preferable examples of the vinyl polymer and the monomer constituting the vinyl polymer include those described in JP-A Nos. 2001-181549 and 2002-88294. Further, a radical transfer of a vinyl monomer using a chain transfer agent having a dissociable group (or a substituent that can be derived to a dissociable group), a polymerization initiator, an iniferter, a dissociable group (either an initiator or a terminator) Alternatively, a vinyl polymer in which a dissociable group is introduced at the end of a polymer chain by ionic polymerization using a compound having a substituent that can be derived from a dissociable group can also be used.
In addition, preferable examples of the condensation polymer and the monomer constituting the condensation polymer include those described in JP-A-2001-247787.
　樹脂粒子は、分散安定性の観点から、親水性の構成単位と、芳香族基含有モノマー又は環状脂肪族基含有モノマーに由来する構成単位と、を含む水不溶性ポリマーを含むことが好ましい。 The resin particles preferably contain a water-insoluble polymer containing a hydrophilic structural unit and a structural unit derived from an aromatic group-containing monomer or a cyclic aliphatic group-containing monomer from the viewpoint of dispersion stability.
　「親水性の構成単位」は、親水性基含有モノマーに由来するものであれば、特に制限はなく、１種の親水性基含有モノマーに由来するものであってもよいし、２種以上の親水性基含有モノマーに由来するものであってもよい。親水性基としては、スルホ基を除いては特に制限はなく、解離性基であってもよいし、ノニオン性親水性基であってもよい。
　親水性基は、形成された乳化状態又は分散状態の安定性の観点から、解離性基であることが好ましく、アニオン性の解離基であることがより好ましい。すなわち、樹脂粒子としては、アニオン性の解離基を有する樹脂粒子であることが好ましい。
　解離性基としては、カルボキシ基、リン酸基等が挙げられる。
　これらの中でも、解離性基としては、インク組成物を構成した場合の定着性の観点から、カルボキシ基が好ましい。 The “hydrophilic structural unit” is not particularly limited as long as it is derived from a hydrophilic group-containing monomer, and may be derived from one type of hydrophilic group-containing monomer, or two or more types It may be derived from a hydrophilic group-containing monomer. The hydrophilic group is not particularly limited except for a sulfo group, and may be a dissociable group or a nonionic hydrophilic group.
The hydrophilic group is preferably a dissociable group, more preferably an anionic dissociative group, from the viewpoint of the stability of the formed emulsified state or dispersed state. That is, the resin particles are preferably resin particles having an anionic dissociation group.
Examples of the dissociable group include a carboxy group and a phosphate group.
Among these, the dissociable group is preferably a carboxy group from the viewpoint of fixability when the ink composition is constituted.
　親水性基含有モノマーは、分散安定性と凝集性の観点から、解離性基含有モノマーであることが好ましく、解離性基とエチレン性不飽和結合とを有する解離性基含有モノマーであることがより好ましい。
　解離性基含有モノマーとしては、不飽和カルボン酸モノマー、不飽和スルホン酸モノマー、不飽和リン酸モノマー等が挙げられる。 The hydrophilic group-containing monomer is preferably a dissociable group-containing monomer from the viewpoint of dispersion stability and aggregability, and more preferably a dissociable group-containing monomer having a dissociable group and an ethylenically unsaturated bond. preferable.
Examples of the dissociable group-containing monomer include an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, and an unsaturated phosphoric acid monomer.
　不飽和カルボン酸モノマーの具体例としては、アクリル酸、メタクリル酸、クロトン酸、イタコン酸、マレイン酸、フマル酸、シトラコン酸、２－メタクリロイルオキシメチルコハク酸等が挙げられる。
　不飽和リン酸モノマーの具体例としては、ビニルホスホン酸、ビニルホスフェート、ビス（メタクリロキシエチル）ホスフェート、ジフェニル－２－アクリルオキシエチルホスフェート、ジフェニル－２－メタクリルオキシエチルホスフェート、ジブチル－２－アクリルオキシエチルホスフェート等が挙げられる。
　これらの中でも、解離性基含有モノマーとしては、分散安定性及び吐出安定性の観点から、不飽和カルボン酸モノマーが好ましく、アクリル酸及びメタクリル酸の少なくとも一方がより好ましい。 Specific examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, 2-methacryloyloxymethyl succinic acid and the like.
Specific examples of unsaturated phosphoric acid monomers include vinyl phosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloxyethyl phosphate, diphenyl-2-methacryloxyethyl phosphate, dibutyl-2-acryloxy Examples thereof include ethyl phosphate.
Among these, as the dissociable group-containing monomer, an unsaturated carboxylic acid monomer is preferable from the viewpoint of dispersion stability and ejection stability, and at least one of acrylic acid and methacrylic acid is more preferable.
　樹脂粒子は、分散安定性及び後述の前処理液と接触した際の凝集速度の観点から、カルボキシ基を有するポリマーを含むことが好ましく、カルボキシ基を有し、かつ、酸価が２５ｍｇＫＯＨ／ｇ～１００ｍｇＫＯＨ／ｇであるポリマーを含むことがより好ましい。さらに、酸価は、自己分散性及び後述の前処理液と接触した際の凝集速度の観点から、２５ｍｇＫＯＨ／ｇ～８０ｍｇＫＯＨ／ｇであることが更に好ましく、３０ｍｇＫＯＨ／ｇ～６５ｍｇＫＯＨであることが特に好ましい。
　特に、樹脂粒子の酸価は、２５ｍｇＫＯＨ／ｇ以上であると分散安定性が良好になり、１００ｍｇＫＯＨ／ｇ以下であると凝集性が向上する。
　なお、樹脂粒子の酸価は、日本工業規格（ＪＩＳ　Ｋ００７０：１９９２）に記載の方法により測定される値である。 The resin particles preferably contain a polymer having a carboxy group from the viewpoint of dispersion stability and agglomeration rate when in contact with the pretreatment liquid described later, and have a carboxy group and an acid value of 25 mgKOH / g to More preferably, it contains a polymer that is 100 mg KOH / g. Furthermore, the acid value is more preferably from 25 mgKOH / g to 80 mgKOH / g, particularly from 30 mgKOH / g to 65 mgKOH, from the viewpoint of self-dispersibility and aggregation rate when contacting with the pretreatment liquid described later. preferable.
In particular, when the acid value of the resin particles is 25 mgKOH / g or more, the dispersion stability is good, and when it is 100 mgKOH / g or less, the cohesiveness is improved.
The acid value of the resin particles is a value measured by the method described in Japanese Industrial Standard (JIS K0070: 1992).
　芳香族基含有モノマーは、芳香族基と重合性基とを含む化合物であれば、特に制限はない。芳香族基は、芳香族炭化水素に由来する基であってもよいし、芳香族複素環に由来する基であってもよい。芳香族基としては、水性媒体中での粒子形状安定性の観点から、芳香族炭化水素に由来する芳香族基が好ましい。
　また、重合性基は、縮重合性の重合性基であってもよいし、付加重合性の重合性基であってもよい。重合性基としては、水性媒体中での粒子形状安定性の観点から、付加重合性の重合性基であることが好ましく、エチレン性不飽和結合を含む基であることがより好ましい。 The aromatic group-containing monomer is not particularly limited as long as it is a compound containing an aromatic group and a polymerizable group. The aromatic group may be a group derived from an aromatic hydrocarbon or a group derived from an aromatic heterocycle. The aromatic group is preferably an aromatic group derived from an aromatic hydrocarbon from the viewpoint of particle shape stability in an aqueous medium.
The polymerizable group may be a polycondensable polymerizable group or an addition polymerizable polymerizable group. The polymerizable group is preferably an addition polymerizable polymerizable group from the viewpoint of particle shape stability in an aqueous medium, and more preferably a group containing an ethylenically unsaturated bond.
　芳香族基含有モノマーは、芳香族炭化水素に由来する芳香族基とエチレン性不飽和結合とを有するモノマーであることが好ましい。
　芳香族基含有モノマーは、１種のみ用いてもよいし、２種以上を組み合わせて用いてもよい。
　芳香族基含有モノマーとしては、フェノキシエチル（メタ）アクリレート、ベンジル（メタ）アクリレート、フェニル（メタ）アクリレート、スチレン系モノマー等が挙げられる。これらの中でも、芳香族基含有モノマーとしては、ポリマー鎖の親水性と疎水性とのバランス及びインク定着性の観点から、芳香族基含有（メタ）アクリレートモノマーが好ましく、フェノキシエチル（メタ）アクリレート、ベンジル（メタ）アクリレート、及びフェニル（メタ）アクリレートからなる群より選ばれる少なくとも１種がより好ましく、フェノキシエチル（メタ）アクリレート及びベンジル（メタ）アクリレートからなる群より選ばれる少なくとも１種が更に好ましい。 The aromatic group-containing monomer is preferably a monomer having an aromatic group derived from an aromatic hydrocarbon and an ethylenically unsaturated bond.
One type of aromatic group-containing monomer may be used, or two or more types may be used in combination.
Examples of the aromatic group-containing monomer include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, and a styrene monomer. Among these, as the aromatic group-containing monomer, an aromatic group-containing (meth) acrylate monomer is preferable from the viewpoint of the balance between the hydrophilicity and hydrophobicity of the polymer chain and ink fixability, and phenoxyethyl (meth) acrylate, At least one selected from the group consisting of benzyl (meth) acrylate and phenyl (meth) acrylate is more preferable, and at least one selected from the group consisting of phenoxyethyl (meth) acrylate and benzyl (meth) acrylate is more preferable.
　環状脂肪族基含有モノマーは、環状脂肪族炭化水素に由来する環状脂肪族基とエチレン性不飽和結合とを有するモノマーであることが好ましく、環状脂肪族基含有（メタ）アクリレートモノマー（以下、「脂環式（メタ）アクリレート」ともいう。）であることがより好ましい。
　脂環式（メタ）アクリレートとは、（メタ）アクリル酸に由来する構成部位と、アルコールに由来する構成部位とを含み、アルコールに由来する構成部位に、無置換又は置換された脂環式炭化水素基（環状脂肪族基）を少なくとも１つ含む構造を有しているものである。なお、脂環式炭化水素基は、アルコールに由来する構成部位そのものであってもよいし、連結基を介してアルコールに由来する構成部位に結合していてもよい。 The cycloaliphatic group-containing monomer is preferably a monomer having a cycloaliphatic group derived from a cycloaliphatic hydrocarbon and an ethylenically unsaturated bond, and a cycloaliphatic group-containing (meth) acrylate monomer (hereinafter, “ More preferably, it is also referred to as “alicyclic (meth) acrylate”.
An alicyclic (meth) acrylate includes a component derived from (meth) acrylic acid and a component derived from alcohol, and the component derived from alcohol is unsubstituted or substituted with alicyclic carbonization. It has a structure containing at least one hydrogen group (cycloaliphatic group). In addition, the alicyclic hydrocarbon group may be a constituent site derived from alcohol itself, or may be bonded to a constituent site derived from alcohol via a linking group.
　脂環式炭化水素基としては、環状の非芳香族炭化水素基を含むものであれば、特に制限はなく、単環式炭化水素基であってもよいし、２環式炭化水素基であってもよいし、３環式以上の多環式炭化水素基であってもよい。
　脂環式炭化水素基としては、シクロペンチル基、シクロヘキシル基等のシクロアルキル基、シクロアルケニル基、ビシクロヘキシル基、ノルボルニル基、イソボルニル基、ジシクロペンタニル基、ジシクロペンテニル基、アダマンチル基、デカヒドロナフタレニル基、ペルヒドロフルオレニル基、トリシクロ［５．２．１．０２，６］デカニル基、ビシクロ［４．３．０］ノナンなどが挙げられる。
　脂環式炭化水素基は、更に置換基を有してもよい。
　置換基としては、アルキル基、アルケニル基、アリール基、アラルキル基、アルコキシ基、水酸基、１級アミノ基、２級アミノ基、３級アミノ基、アルキルカルボニル基、アリールカルボニル基、シアノ基等が挙げられる。
　また、脂環式炭化水素基は、更に縮合環を形成していてもよい。
　脂環式炭化水素基としては、粘度及び溶解性の観点から、脂環式炭化水素基部分の炭素数が５～２０であることが好ましい。 The alicyclic hydrocarbon group is not particularly limited as long as it includes a cyclic non-aromatic hydrocarbon group, and may be a monocyclic hydrocarbon group or a bicyclic hydrocarbon group. It may be a tricyclic or more polycyclic hydrocarbon group.
The alicyclic hydrocarbon group includes a cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, a cycloalkenyl group, a bicyclohexyl group, a norbornyl group, an isobornyl group, a dicyclopentanyl group, a dicyclopentenyl group, an adamantyl group, a decahydro group. Naphthalenyl group, perhydrofluorenyl group, tricyclo [5.2.1.0 2,6 ] decanyl group, bicyclo [4.3.0] nonane and the like can be mentioned.
The alicyclic hydrocarbon group may further have a substituent.
Examples of the substituent include an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, a hydroxyl group, a primary amino group, a secondary amino group, a tertiary amino group, an alkylcarbonyl group, an arylcarbonyl group, and a cyano group. It is done.
The alicyclic hydrocarbon group may further form a condensed ring.
The alicyclic hydrocarbon group preferably has 5 to 20 carbon atoms in the alicyclic hydrocarbon group portion from the viewpoint of viscosity and solubility.
　以下、脂環式（メタ）アクリレートの具体例を示す。但し、脂環式（メタ）アクリレートは、これらの具体例に限定されるものではない。
　単環式（メタ）アクリレートとしては、例えば、シクロプロピル（メタ）アクリレート、シクロブチル（メタ）アクリレート、シクロペンチル（メタ）アクリレート、シクロヘキシル（メタ）アクリレート、シクロヘプチル（メタ）アクリレート、シクロオクチル（メタ）アクリレート、シクロノニル（メタ）アクリレート、シクロデシル（メタ）アクリレート等のシクロアルキル基の炭素数が３～１０のシクロアルキル（メタ）アクリレートが挙げられる。
　２環式（メタ）アクリレートとしては、イソボルニル（メタ）アクリレート、ノルボルニル（メタ）アクリレート等が挙げられる。
　３環式（メタ）アクリレートとしては、アダマンチル（メタ）アクリレート、ジシクロペンタニル（メタ）アクリレート、ジシクロペンテニルオキシエチル（メタ）アクリレート等が挙げられる。
　これらの脂環式（メタ）アクリレートは、１種のみ用いてもよいし、２種以上を組み合わせて用いてもよい。 Hereinafter, specific examples of the alicyclic (meth) acrylate will be shown. However, alicyclic (meth) acrylate is not limited to these specific examples.
Examples of monocyclic (meth) acrylates include cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, and cyclooctyl (meth) acrylate. And cycloalkyl (meth) acrylates having 3 to 10 carbon atoms in the cycloalkyl group such as cyclononyl (meth) acrylate and cyclodecyl (meth) acrylate.
Examples of the bicyclic (meth) acrylate include isobornyl (meth) acrylate and norbornyl (meth) acrylate.
Examples of the tricyclic (meth) acrylate include adamantyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate.
These alicyclic (meth) acrylates may be used alone or in combination of two or more.
　これらの中でも、脂環式（メタ）アクリレートとしては、樹脂粒子の分散安定性、定着性、及びブロッキング耐性の観点から、２環式（メタ）アクリレート及び３環式以上の多環式（メタ）アクリレートからなる群より選ばれる少なくとも１種であることが好ましく、イソボルニル（メタ）アクリレート、アダマンチル（メタ）アクリレート、及びジシクロペンタニル（メタ）アクリレートからなる群より選ばれる少なくとも１種であることがより好ましい。 Among these, as the alicyclic (meth) acrylate, from the viewpoint of dispersion stability of resin particles, fixability, and blocking resistance, bicyclic (meth) acrylate and tricyclic or higher polycyclic (meth) It is preferably at least one selected from the group consisting of acrylates, and at least one selected from the group consisting of isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate. More preferred.
　樹脂粒子の形成に用いる樹脂としては、（メタ）アクリレートモノマーに由来する構成単位を含むアクリル系樹脂が好ましく、芳香族基含有（メタ）アクリレートモノマー又は脂環式（メタ）アクリレートに由来する構成単位を含むアクリル系樹脂がより好ましく、芳香族基含有（メタ）アクリレートモノマー又は脂環式（メタ）アクリレートに由来する構成単位を含み、かつ、その含有量が１０質量％～９５質量％であることが好ましい。
　芳香族基含有（メタ）アクリレートモノマー又は脂環式（メタ）アクリレートの含有量が１０質量％～９５質量％であることで、乳化状態又は分散状態の安定性が向上し、更にインク粘度の上昇を抑制することができる。
　芳香族基含有（メタ）アクリレートモノマー又は脂環式（メタ）アクリレートの含有量は、分散状態の安定性、芳香環同士又は脂環同士の疎水性相互作用による水性媒体中での粒子形状の安定化、及び粒子の適度な疎水化による水溶性成分量の低下の観点から、１５質量％～９０質量％であることがより好ましく、１５質量％～８０質量％であることが更に好ましく、２５質量％～７０質量％であることが特に好ましい。 The resin used for forming the resin particles is preferably an acrylic resin containing a structural unit derived from a (meth) acrylate monomer, and a structural unit derived from an aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate. An acrylic resin containing is more preferable, it contains a structural unit derived from an aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate, and its content is 10% by mass to 95% by mass Is preferred.
When the content of the aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate is 10% by mass to 95% by mass, the stability of the emulsified state or the dispersed state is improved, and the ink viscosity is further increased. Can be suppressed.
The content of the aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate is stable in the dispersion state, and the particle shape stability in an aqueous medium due to the hydrophobic interaction between aromatic rings or alicyclic rings. From the viewpoint of reducing the amount of the water-soluble component due to the formation of particles and appropriate hydrophobicity of the particles, the content is more preferably 15% by mass to 90% by mass, further preferably 15% by mass to 80% by mass, and more preferably 25% by mass % To 70% by mass is particularly preferable.
　樹脂粒子の形成に用いる樹脂は、例えば、芳香族基含有モノマー又は環状脂肪族基含有モノマーに由来する構成単位と、解離性基含有モノマーに由来する構成単位とを含んで構成することができ、必要に応じて、その他の構成単位を更に含んでもよい。 The resin used for forming the resin particles can be configured to include, for example, a structural unit derived from an aromatic group-containing monomer or a cycloaliphatic group-containing monomer and a structural unit derived from a dissociable group-containing monomer. Other structural units may be further included as necessary.
　その他の構成単位を形成するモノマーとしては、芳香族基含有モノマー及び解離性基含有モノマーと共重合可能なモノマーであれば、特に制限はない。
　その他の構成単位を形成するモノマーとしては、ポリマー骨格の柔軟性及びガラス転移温度（Ｔｇ）制御の容易さの観点から、アルキル基含有モノマーが好ましい。
　アルキル基含有モノマーとしては、メチル（メタ）アクリレート、エチル（メタ）アクリレート、イソプロピル（メタ）アクリレート、ｎ－プロピル（メタ）アクリレート、ｎ－ブチル（メタ）アクリレート、イソブチル（メタ）アクリレート、ｔ－ブチル（メタ）アクリレート、ヘキシル（メタ）アクリレート、エチルヘキシル（メタ）アクリレート等のアルキル（メタ）アクリレート；ヒドロキシメチル（メタ）アクリレート、２－ヒドロキシエチル（メタ）アクリレート、２－ヒドロキシプロピル（メタ）アクリレート、４－ヒドロキシブチル（メタ）アクリレート、ヒドロキシペンチル（メタ）アクリレート、ヒドロキシヘキシル（メタ）アクリレート等の水酸基を有するエチレン性不飽和モノマー；ジメチルアミノエチル（メタ）アクリレート等のジアルキルアミノアルキル（メタ）アクリレート；Ｎ－ヒドロキシメチル（メタ）アクリルアミド、Ｎーヒドロキシエチル（メタ）アクリルアミド、Ｎ－ヒドロキシブチル（メタ）アクリルアミド等のＮ－ヒドロキシアルキル（メタ）アクリルアミド；Ｎ－メトキシメチル（メタ）アクリルアミド、Ｎ－エトキシメチル（メタ）アクリルアミド、Ｎ－（ｎ－，イソ）ブトキシメチル（メタ）アクリルアミド、Ｎ－メトキシエチル（メタ）アクリルアミド、Ｎ－エトキシエチル（メタ）アクリルアミド、Ｎ－（ｎ－、イソ）ブトキシエチル（メタ）アクリルアミド等のＮ－アルコキシアルキル（メタ）アクリルアミド等の（メタ）アクリルアミドなどが挙げられる。 The monomer that forms the other structural unit is not particularly limited as long as it is a monomer copolymerizable with an aromatic group-containing monomer and a dissociable group-containing monomer.
As the monomer that forms the other structural unit, an alkyl group-containing monomer is preferable from the viewpoint of flexibility of the polymer skeleton and easy control of the glass transition temperature (Tg).
Examples of alkyl group-containing monomers include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl. Alkyl (meth) acrylates such as (meth) acrylate, hexyl (meth) acrylate, and ethylhexyl (meth) acrylate; hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4 -Ethylenically unsaturated monomers having a hydroxyl group such as hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyhexyl (meth) acrylate; dimethylaminoethyl (meth) Dialkylaminoalkyl (meth) acrylates such as acrylate; N-hydroxyalkyl (meth) acrylamides such as N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N-hydroxybutyl (meth) acrylamide; N- Methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N- (n-, iso) butoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, N And (meth) acrylamides such as N-alkoxyalkyl (meth) acrylamides such as-(n-, iso) butoxyethyl (meth) acrylamide.
　樹脂粒子を構成する水不溶性ポリマーの重量平均分子量（Ｍｗ）は、３，０００～２００，０００であることが好ましく、５，０００～１５０，０００であることがより好ましく、１０，０００～１００，０００であることが更に好ましい。
　水不溶性ポリマーの重量平均分子量（Ｍｗ）を３，０００以上とすることで水溶性成分量を効果的に抑制することができる。
　また、水不溶性ポリマーの重量平均分子量（Ｍｗ）を２００，０００以下とすることで、分散安定性を高めることができる。
　なお、水不溶性ポリマーの重量平均分子量（Ｍｗ）は、既述のオーバーコート液に含まれる水不溶性樹脂の重量平均分子量（Ｍｗ）の測定と同様の方法により測定される値である。 The weight average molecular weight (Mw) of the water-insoluble polymer constituting the resin particles is preferably 3,000 to 200,000, more preferably 5,000 to 150,000, and 10,000 to 100,000. More preferably, it is 000.
By setting the weight average molecular weight (Mw) of the water-insoluble polymer to 3,000 or more, the amount of the water-soluble component can be effectively suppressed.
Moreover, dispersion stability can be improved by making the weight average molecular weight (Mw) of a water-insoluble polymer into 200,000 or less.
The weight average molecular weight (Mw) of the water-insoluble polymer is a value measured by the same method as the measurement of the weight average molecular weight (Mw) of the water-insoluble resin contained in the overcoat liquid described above.
　樹脂粒子を構成する水不溶性ポリマーは、ポリマーの親疎水性制御の観点から、芳香族基含有（メタ）アクリレートモノマーに由来する構成単位（好ましくは、フェノキシエチル（メタ）アクリレートに由来する構成単位及び／又はベンジル（メタ）アクリレートに由来する構成単位）又は環状脂肪族基含有モノマー（好ましくは脂環式（メタ）アクリレート）を、共重合比率として樹脂粒子の全質量の１５質量％～８０質量％を含むことが好ましい。
　また、水不溶性ポリマーは、ポリマーの親疎水性制御の観点から、芳香族基含有（メタ）アクリレートモノマー又は脂環式（メタ）アクリレートモノマーに由来する構成単位を共重合比率として１５質量％～８０質量％と、カルボキシ基含有モノマーに由来する構成単位と、アルキル基含有モノマーに由来する構成単位（好ましくは、（メタ）アクリル酸のアルキルエステルに由来する構成単位）とを含むことが好ましく、フェノキシエチル（メタ）アクリレートに由来する構成単位及び／又はベンジル（メタ）アクリレートに由来する構成単位を共重合比率として１５質量％～８０質量％と、カルボキシ基含有モノマーに由来する構成単位と、アルキル基含有モノマーに由来する構成単位（好ましくは、（メタ）アクリル酸の炭素数１～４のアルキルエステルに由来する構成単位）とを含むことがより好ましい。
　また、水不溶性ポリマーは、酸価が２５ｍｇＫＯＨ／ｇ～１００ｍｇＫＯＨ／ｇであり、かつ、重量平均分子量（Ｍｗ）が３，０００～２００，０００であることが好ましく、酸価が２５ｍｇＫＯＨ／ｇ～９５ｍｇＫＯＨ／ｇであり、かつ、重量平均分子量（Ｍｗ）が５，０００～１５０，０００であることがより好ましい。
　なお、水不溶性ポリマーの酸価は、日本工業規格（ＪＩＳ　Ｋ００７０：１９９２）に記載の方法により測定される値である。 The water-insoluble polymer constituting the resin particle is a structural unit derived from an aromatic group-containing (meth) acrylate monomer (preferably a structural unit derived from phenoxyethyl (meth) acrylate and / or from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. Or a structural unit derived from benzyl (meth) acrylate) or a cycloaliphatic group-containing monomer (preferably alicyclic (meth) acrylate), and a copolymerization ratio of 15% by mass to 80% by mass of the total mass of the resin particles. It is preferable to include.
The water-insoluble polymer has a copolymerization ratio of 15% by mass to 80% by mass of a structural unit derived from an aromatic group-containing (meth) acrylate monomer or alicyclic (meth) acrylate monomer from the viewpoint of controlling the hydrophilicity / hydrophobicity of the polymer. %, A structural unit derived from a carboxy group-containing monomer, and a structural unit derived from an alkyl group-containing monomer (preferably a structural unit derived from an alkyl ester of (meth) acrylic acid). 15% by mass to 80% by mass of a structural unit derived from (meth) acrylate and / or a structural unit derived from benzyl (meth) acrylate, a structural unit derived from a carboxy group-containing monomer, and an alkyl group Constituent units derived from monomers (preferably (meth) acrylic acid having 1 to 4 carbon atoms More preferably contains a structural unit) and derived from an alkyl ester.
The water-insoluble polymer preferably has an acid value of 25 mgKOH / g to 100 mgKOH / g, a weight average molecular weight (Mw) of 3,000 to 200,000, and an acid value of 25 mgKOH / g to 95 mgKOH. More preferably, the weight average molecular weight (Mw) is 5,000 to 150,000.
The acid value of the water-insoluble polymer is a value measured by the method described in Japanese Industrial Standard (JIS K0070: 1992).
　以下、水不溶性ポリマーの具体例（例示化合物Ｂ－０１～Ｂ－２３）を示す。但し、水不溶性ポリマーは、これらの具体例に限定されない。なお、具体例における括弧内の数値は、共重合成分の質量比を表す。 Specific examples of the water-insoluble polymer (Exemplary Compounds B-01 to B-23) are shown below. However, the water-insoluble polymer is not limited to these specific examples. In addition, the numerical value in the bracket | parenthesis in a specific example represents the mass ratio of a copolymerization component.
　Ｂ－０１：フェノキシエチルアクリレート／メチルメタクリレート／アクリル酸共重合体（５０／４５／５）
　Ｂ－０２：フェノキシエチルアクリレート／ベンジルメタクリレート／イソブチルメタクリレート／メタクリル酸共重合体（３０／３５／２９／６）
　Ｂ－０３：フェノキシエチルメタクリレート／イソブチルメタクリレート／メタクリル酸共重合体（５０／４４／６）
　Ｂ－０４：フェノキシエチルアクリレート／メチルメタクリレート／エチルアクリレート／アクリル酸共重合体（３０／５５／１０／５）
　Ｂ－０５：ベンジルメタクリレート／イソブチルメタクリレート／メタクリル酸共重合体（３５／５９／６）
　Ｂ－０６：スチレン／フェノキシエチルアクリレート／メチルメタクリレート／アクリル酸共重合体（１０／５０／３５／５）
　Ｂ－０７：ベンジルアクリレート／メチルメタクリレート／アクリル酸共重合体（５５／４０／５）
　Ｂ－０８：フェノキシエチルメタクリレート／ベンジルアクリレート／メタクリル酸共重合体（４５／４７／８）
　Ｂ－０９：スチレン／フェノキシエチルアクリレート／ブチルメタクリレート／アクリル酸共重合体（５／４８／４０／７）
　Ｂ－１０：ベンジルメタクリレート／イソブチルメタクリレート／シクロヘキシルメタクリレート／メタクリル酸共重合体（３５／３０／３０／５）
　Ｂ－１１：フェノキシエチルアクリレート／メチルメタクリレート／ブチルアクリレート／メタクリル酸共重合体（１２／５０／３０／８）
　Ｂ－１２：ベンジルアクリレート／イソブチルメタクリレート／アクリル酸共重合体（９３／２／５）
　Ｂ－１３：スチレン／フェノキシエチルメタクリレート／ブチルアクリレート／アクリル酸共重合体（５０／５／２０／２５）
　Ｂ－１４：スチレン／ブチルアクリレート／アクリル酸共重合体（６２／３５／３）
　Ｂ－１５：メチルメタクリレート／フェノキシエチルアクリレート／アクリル酸共重合体（４５／５１／４）
　Ｂ－１６：メチルメタクリレート／フェノキシエチルアクリレート／アクリル酸共重合体（４５／４９／６）
　Ｂ－１７：メチルメタクリレート／フェノキシエチルアクリレート／アクリル酸共重合体（４５／４８／７）
　Ｂ－１８：メチルメタクリレート／フェノキシエチルアクリレート／アクリル酸共重合体（４５／４７／８）
　Ｂ－１９：メチルメタクリレート／フェノキシエチルアクリレート／アクリル酸共重合体（４５／４５／１０）
　Ｂ－２０：メチルメタクリレート／イソボルニルメタクリレート／メタクリル酸共重合体（２０／７２／８）
　Ｂ－２１：メチルメタクリレート／イソボルニルメタクリレート／メタクリル酸共重合体（４０／５２／８）
　Ｂ－２２：メチルメタクリレート／イソボルニルメタクリレート／ジシクロペンタニルメタクリレート／メタクリル酸共重合体（２０／６２／１０／８）
　Ｂ－２３：メチルメタクリレート／ジシクロペンタニルメタクリレート／メタクリル酸共重合体（２０／７２／８） B-01: Phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (50/45/5)
B-02: Phenoxyethyl acrylate / benzyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (30/35/29/6)
B-03: Phenoxyethyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (50/44/6)
B-04: Phenoxyethyl acrylate / methyl methacrylate / ethyl acrylate / acrylic acid copolymer (30/55/10/5)
B-05: benzyl methacrylate / isobutyl methacrylate / methacrylic acid copolymer (35/59/6)
B-06: Styrene / phenoxyethyl acrylate / methyl methacrylate / acrylic acid copolymer (10/50/35/5)
B-07: benzyl acrylate / methyl methacrylate / acrylic acid copolymer (55/40/5)
B-08: Phenoxyethyl methacrylate / benzyl acrylate / methacrylic acid copolymer (45/47/8)
B-09: Styrene / phenoxyethyl acrylate / butyl methacrylate / acrylic acid copolymer (5/48/40/7)
B-10: benzyl methacrylate / isobutyl methacrylate / cyclohexyl methacrylate / methacrylic acid copolymer (35/30/30/5)
B-11: Phenoxyethyl acrylate / methyl methacrylate / butyl acrylate / methacrylic acid copolymer (12/50/30/8)
B-12: benzyl acrylate / isobutyl methacrylate / acrylic acid copolymer (93/2/5)
B-13: Styrene / phenoxyethyl methacrylate / butyl acrylate / acrylic acid copolymer (50/5/20/25)
B-14: Styrene / butyl acrylate / acrylic acid copolymer (62/35/3)
B-15: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/51/4)
B-16: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/49/6)
B-17: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/48/7)
B-18: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/47/8)
B-19: Methyl methacrylate / phenoxyethyl acrylate / acrylic acid copolymer (45/45/10)
B-20: Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (20/72/8)
B-21: Methyl methacrylate / isobornyl methacrylate / methacrylic acid copolymer (40/52/8)
B-22: Methyl methacrylate / isobornyl methacrylate / dicyclopentanyl methacrylate / methacrylic acid copolymer (20/62/10/8)
B-23: Methyl methacrylate / dicyclopentanyl methacrylate / methacrylic acid copolymer (20/72/8)
　樹脂粒子に含まれる水不溶性ポリマーの製造方法は、特に制限されない。
　水不溶性ポリマーの製造方法としては、重合性界面活性剤の存在下に、乳化重合を行い、界面活性剤と水不溶性ポリマーとを共有結合させる方法、上記親水性基含有モノマーと芳香族基含有モノマー又は脂環族基含有モノマーとを含むモノマー混合物を溶液重合法、塊状重合法等の公知の重合法により、共重合させる方法等が挙げられる。
　重合法としては、凝集速度及びインク組成物とした場合の打滴安定性の観点から、溶液重合法が好ましく、有機溶剤を用いた溶液重合法がより好ましい。 The method for producing the water-insoluble polymer contained in the resin particles is not particularly limited.
As a method for producing a water-insoluble polymer, emulsion polymerization is carried out in the presence of a polymerizable surfactant to covalently bond the surfactant and the water-insoluble polymer, the hydrophilic group-containing monomer and the aromatic group-containing monomer. Alternatively, a method of copolymerizing a monomer mixture containing an alicyclic group-containing monomer by a known polymerization method such as a solution polymerization method or a bulk polymerization method may be used.
The polymerization method is preferably a solution polymerization method, more preferably a solution polymerization method using an organic solvent, from the viewpoint of the aggregation rate and droplet ejection stability when an ink composition is used.
　樹脂粒子は、凝集速度の観点から、有機溶剤中で合成されたポリマーを含み、ポリマーがアニオン性基（好ましくは、カルボキシ基）を有し、（好ましくは、酸価が２０ｍｇＫＯＨ／ｇ～１００ｍｇＫＯＨ／ｇであって）、ポリマーのアニオン性基（好ましくは、カルボキシ基）の一部又は全部は中和され、水を連続相とするポリマー分散物として調製されたものであることが好ましい。
　すなわち、樹脂粒子の製造は、有機溶剤中でポリマーを合成する工程と、ポリマーのアニオン性基（好ましくは、カルボキシ基）の少なくとも一部が中和された水性分散物とする分散工程と、を設けて行なうことが好ましい。 The resin particles include a polymer synthesized in an organic solvent from the viewpoint of aggregation rate, the polymer has an anionic group (preferably a carboxy group), and preferably has an acid value of 20 mgKOH / g to 100 mgKOH / g), and a part or all of anionic groups (preferably carboxy groups) of the polymer are preferably neutralized and prepared as a polymer dispersion having water as a continuous phase.
That is, the production of the resin particles includes a step of synthesizing a polymer in an organic solvent, and a dispersion step of forming an aqueous dispersion in which at least a part of an anionic group (preferably a carboxy group) of the polymer is neutralized. It is preferable to provide it.
　分散工程は、次の工程（１）及び工程（２）を含むことが好ましい。
　工程（１）：ポリマー（即ち、水不溶性ポリマー）、有機溶剤、中和剤、及び水性媒体を含有する混合物を、撹拌する工程
　工程（２）：混合物から有機溶剤を除去する工程 The dispersion step preferably includes the following step (1) and step (2).
Step (1): A step of stirring a mixture containing a polymer (that is, a water-insoluble polymer), an organic solvent, a neutralizing agent, and an aqueous medium. Step (2): A step of removing the organic solvent from the mixture.
　工程（１）は、最初にポリマー（即ち、水不溶性ポリマー）を有機溶剤に溶解させ、次に中和剤と水性媒体とを徐々に加えて混合し、撹拌して分散体を得る工程であることが好ましい。有機溶剤中に溶解した水不溶性ポリマー溶液中に、中和剤と水性媒体とを添加することで、強いせん断力を必要とせずに、より保存安定性の高い粒子径の樹脂粒子を得ることができる。
　混合物の撹拌方法は、特に制限されず、一般に用いられる混合撹拌装置を用いる撹拌方法が挙げられる。また、必要に応じて、超音波分散機、高圧ホモジナイザー等の分散機を用いて、混合物を撹拌してもよい。
　また、工程（２）においては、工程（１）で得られた分散体から、減圧蒸留等の常法により有機溶剤を留去して水系へと転相することで樹脂粒子の水性分散物を得ることができる。得られた水性分散物中の有機溶剤は、実質的に除去されており、有機溶剤の量は、好ましくは０．２質量％以下、更に好ましくは０．１質量％以下である。 Step (1) is a step in which a polymer (that is, a water-insoluble polymer) is first dissolved in an organic solvent, and then a neutralizing agent and an aqueous medium are gradually added and mixed, followed by stirring to obtain a dispersion. It is preferable. By adding a neutralizing agent and an aqueous medium to a water-insoluble polymer solution dissolved in an organic solvent, resin particles having a particle size with higher storage stability can be obtained without requiring strong shearing force. it can.
The stirring method of a mixture is not specifically limited, The stirring method using the mixing stirring apparatus generally used is mentioned. Moreover, you may stir a mixture using dispersers, such as an ultrasonic disperser and a high-pressure homogenizer, as needed.
In step (2), the aqueous dispersion of resin particles is obtained by distilling off the organic solvent from the dispersion obtained in step (1) by a conventional method such as distillation under reduced pressure and phase-inversion into an aqueous system. Obtainable. The organic solvent in the obtained aqueous dispersion is substantially removed, and the amount of the organic solvent is preferably 0.2% by mass or less, more preferably 0.1% by mass or less.
　有機溶剤としては、アルコール系溶剤、ケトン系溶剤、及びエーテル系溶剤が好ましく挙げられる。有機溶剤としては、例えば、特開２０１０－１８８６６１号公報の段落［００５９］に例示された有機溶剤を用いることができる。
　中和剤としては、特開２０１０－１８８６６１号公報の段落［００６０］～［００６１］に例示された中和剤を用いることができる。 Preferred examples of the organic solvent include alcohol solvents, ketone solvents, and ether solvents. As the organic solvent, for example, the organic solvent exemplified in paragraph [0059] of JP 2010-188661 A can be used.
As the neutralizing agent, the neutralizing agents exemplified in paragraphs [0060] to [0061] of JP 2010-188661 A can be used.
　樹脂粒子（特に、自己分散性樹脂粒子）の平均粒子径は、体積平均粒子径で１０ｎｍ～４００ｎｍが好ましく、１０ｎｍ～２００ｎｍがより好ましく、１０ｎｍ～１００ｎｍが更に好ましく、１０ｎｍ～５０ｎｍが特に好ましい。
　樹脂粒子の体積平均粒子径が１０ｎｍ以上であると、製造適性が向上する。
　樹脂粒子の体積平均粒子径が４００ｎｍ以下であると、保存安定性が向上する。
　樹脂粒子の粒径分布に関しては、特に制限はなく、広い粒径分布又は単分散性の粒径分布のいずれであってもよい。また、単分散性の粒径分布を持つ樹脂粒子を２種以上混合して使用してもよい。
　なお、樹脂粒子の平均粒子径及び粒径分布は、ナノトラック粒度分布測定装置を用いて、動的光散乱法により体積平均粒径を測定することで求められるものである。ナノトラック粒度分布測定装置としては、例えば、日機装（株）のＵＰＡ－ＥＸ１５０を用いることができる。 The average particle size of the resin particles (particularly self-dispersing resin particles) is preferably 10 nm to 400 nm, more preferably 10 nm to 200 nm, still more preferably 10 nm to 100 nm, and particularly preferably 10 nm to 50 nm.
When the volume average particle diameter of the resin particles is 10 nm or more, the production suitability is improved.
Storage stability improves that the volume average particle diameter of a resin particle is 400 nm or less.
The particle size distribution of the resin particles is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution. Two or more kinds of resin particles having a monodisperse particle size distribution may be mixed and used.
In addition, the average particle diameter and particle size distribution of the resin particles are obtained by measuring the volume average particle diameter by a dynamic light scattering method using a nanotrack particle size distribution measuring apparatus. As the nanotrack particle size distribution measuring apparatus, for example, UPA-EX150 manufactured by Nikkiso Co., Ltd. can be used.
　インク組成物は、樹脂粒子を含む場合、樹脂粒子（好ましくは、自己分散性樹脂粒子）を１種のみ含んでいてもよいし、２種以上を含んでいてもよい。 When the ink composition contains resin particles, the ink composition may contain only one type of resin particles (preferably self-dispersing resin particles), or may contain two or more types.
　インク組成物中における樹脂粒子（好ましくは、自己分散性樹脂粒子）の含有量は、例えば、画像の光沢性の観点から、インク組成物の全質量に対して、１質量％～３０質量％が好ましく、３質量％～１５質量％がより好ましい。 The content of the resin particles (preferably self-dispersing resin particles) in the ink composition is, for example, 1% by mass to 30% by mass with respect to the total mass of the ink composition from the viewpoint of glossiness of the image. Preferably, 3% by mass to 15% by mass is more preferable.
（他の成分）
　インク組成物は、上記の成分以外の他の成分を含んでいてもよい。他の成分としては、例えば、有機溶剤、界面活性剤、及びその他の添加剤が挙げられる。 (Other ingredients)
The ink composition may contain components other than the above components. Examples of other components include organic solvents, surfactants, and other additives.
－有機溶剤－
　インク組成物は、有機溶剤を更に含むことが好ましい。
　インク組成物において、有機溶剤（特に、水溶性有機溶剤）は、乾燥防止及び浸透促進に寄与する。
　本開示でいう「水溶性有機溶剤」とは、２０℃の水１００ｇに対して５ｇ以上溶解する有機溶剤を指す。
　インク組成物が水溶性有機溶剤を更に含むことで、インク組成物をインクジェット法で吐出して画像を記録する際に、インク吐出口でのインクの乾燥によって発生し得るノズルの目詰まりを効果的に防止することができる。
　また、インク組成物が水溶性有機溶剤を更に含むことで、インク組成物を被記録材料により良く浸透させることができる。 -Organic solvent-
The ink composition preferably further contains an organic solvent.
In the ink composition, an organic solvent (particularly a water-soluble organic solvent) contributes to prevention of drying and promotion of penetration.
The “water-soluble organic solvent” in the present disclosure refers to an organic solvent that dissolves 5 g or more in 100 g of water at 20 ° C.
When the ink composition further contains a water-soluble organic solvent, when the ink composition is ejected by an ink jet method to record an image, nozzle clogging that may occur due to drying of the ink at the ink ejection port is effective. Can be prevented.
Further, when the ink composition further contains a water-soluble organic solvent, the ink composition can be penetrated better into the recording material.
　乾燥防止のためには、水より蒸気圧の低い水溶性有機溶剤が好ましい。
　乾燥防止に好適な水溶性有機溶剤の具体的な例としては、エチレングリコール、プロピレングリコール、ジエチレングリコール、ポリエチレングリコール、チオジグリコール、ジチオジグリコール、２－メチル－１，３－プロパンジオール、１，２，６－ヘキサントリオール、アセチレングリコール誘導体、グリセリン、トリメチロールプロパン等の多価アルコール類、エチレングリコールモノメチル（又はエチル）エーテル、ジエチレングリコールモノメチル（又はエチル）エーテル、トリエチレングリコールモノエチル（又はブチル）エーテル、トリプロピレングリコールモノメチル（又はエチル）エーテル等の多価アルコールの低級アルキルエーテル類、２－ピロリドン、Ｎ－メチル－２－ピロリドン、１，３－ジメチル－２－イミダゾリジノン、Ｎ－エチルモルホリン等の複素環類、スルホラン、ジメチルスルホキシド、３－スルホレン等の含硫黄化合物、ジアセトンアルコール、ジエタノールアミン等の多官能化合物、尿素誘導体などが挙げられる。
　これらの中でも、乾燥防止に好適な水溶性有機溶剤としては、グリセリン、ジエチレングリコール等の多価アルコールが好ましい。 In order to prevent drying, a water-soluble organic solvent having a vapor pressure lower than that of water is preferable.
Specific examples of the water-soluble organic solvent suitable for preventing drying include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2 , 6-hexanetriol, acetylene glycol derivatives, polyhydric alcohols such as glycerin and trimethylolpropane, ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether, Lower alkyl ethers of polyhydric alcohols such as tripropylene glycol monomethyl (or ethyl) ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imida Rijinon, heterocyclic compounds such as N- ethylmorpholine, sulfolane, dimethyl sulfoxide, sulfur-containing compounds such as 3-sulfolene, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives.
Among these, polyhydric alcohols such as glycerin and diethylene glycol are preferable as the water-soluble organic solvent suitable for preventing drying.
　浸透促進に好適な水溶性有機溶剤の具体的な例としては、エタノール、イソプロパノール、ブタノール、ジ（トリ）エチレングリコールモノブチルエーテル、トリプロピレングリコールモノメチル（又はエチル）エーテル、１，２－ヘキサンジオール等のアルコールが挙げられる。
　これらの水溶性有機溶剤は、インク組成物中に５質量％～３０質量％含有されることで良好な効果を奏し得る。また、これらの水溶性有機溶剤は、印字及び画像の滲み、並びに紙抜け（所謂、プリントスルー）を起こさない添加量の範囲内で用いられることが好ましい。 Specific examples of water-soluble organic solvents suitable for promoting penetration include ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, tripropylene glycol monomethyl (or ethyl) ether, and 1,2-hexanediol. Examples include alcohol.
These water-soluble organic solvents can exhibit good effects when contained in the ink composition in an amount of 5 to 30% by mass. In addition, these water-soluble organic solvents are preferably used within a range of addition amounts that do not cause printing, image bleeding, and paper loss (so-called print-through).
　また、水溶性有機溶剤は、粘度の調整に用いることができる。
　粘度の調整に用いることができる水溶性有機溶剤の具体的な例としては、アルコール（メタノール、エタノール、プロパノール、イソプロパノール、ブタノール、イソブタノール、ｓｅｃ－ブタノール、ｔ－ブタノール、ペンタノール、ヘキサノール、シクロヘキサノール、ベンジルアルコール等）、多価アルコール類（エチレングリコール、ジエチレングリコール、トリエチレングリコール、ポリエチレングリコール、プロピレングリコール、ジプロピレングリコール、ポリプロピレングリコール、ブチレングリコール、ヘキサンジオール、ペンタンジオール、グリセリン、ヘキサントリオール、チオジグリコール等）、グリコール誘導体（エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、エチレングリコールモノブチルエーテル、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノブチルエーテル、プロピレングリコールモノメチルエーテル、プロピレングリコールモノブチルエーテル、ジプロピレングリコールモノメチルエーテル、トリプロピレングリコールモノメチルエーテル、トリプロピレングリコールモノエチルエーテル、トリエチレングリコールモノメチルエーテル、エチレングリコールジアセテート、エチレングリコールモノメチルエーテルアセテート、トリエチレングリコールモノメチルエーテル、トリエチレングリコールモノエチルエーテル、エチレングリコールモノフェニルエーテル等）、アミン（エタノールアミン、ジエタノールアミン、トリエタノールアミン、Ｎ－メチルジエタノールアミン、Ｎ－エチルジエタノールアミン、モルホリン、Ｎ－エチルモルホリン、エチレンジアミン、ジエチレントリアミン、トリエチレンテトラミン、ポリエチレンイミン、テトラメチルプロピレンジアミン等）、その他の極性溶剤（ホルムアミド、Ｎ，Ｎ－ジメチルホルムアミド、Ｎ，Ｎ－ジメチルアセトアミド、ジメチルスルホキシド、スルホラン、２－ピロリドン、Ｎ－メチル－２－ピロリドン、Ｎ－ビニル－２－ピロリドン、２－オキサゾリドン、１，３－ジメチル－２－イミダゾリジノン、アセトニトリル、アセトン等）などが挙げられる。 The water-soluble organic solvent can be used for adjusting the viscosity.
Specific examples of water-soluble organic solvents that can be used to adjust the viscosity include alcohols (methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol). , Benzyl alcohol, etc.), polyhydric alcohols (ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol Etc.), glycol derivatives (ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol Monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, triethylene glycol monomethyl ether, ethylene glycol di Acetate, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl ether, etc.), amine (ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N Ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine, etc., other polar solvents (formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl) Sulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone and the like.
　インク組成物は、有機溶剤を含む場合、有機溶剤を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 When the ink composition contains an organic solvent, the ink composition may contain only one type of organic solvent or two or more types of organic solvent.
　インク組成物が有機溶剤を含む場合、インク組成物中における有機溶剤の含有量は、インク組成物の全質量に対して、１０質量％～５０質量％が好ましい。 When the ink composition contains an organic solvent, the content of the organic solvent in the ink composition is preferably 10% by mass to 50% by mass with respect to the total mass of the ink composition.
－界面活性剤－
　インク組成物は、界面活性剤を更に含んでいてもよい。
　インク組成物は、界面活性剤を含む場合、界面活性剤を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 -Surfactant-
The ink composition may further contain a surfactant.
When the ink composition contains a surfactant, it may contain only one kind of surfactant or two or more kinds.
　界面活性剤としては、ノニオン性界面活性剤、カチオン性界面活性剤、アニオン性界面活性剤、ベタイン界面活性剤等が挙げられる。
　これらの中でも、界面活性剤としては、凝集速度の観点から、アニオン性界面活性剤又はノニオン性界面活性剤が好ましい。 Examples of the surfactant include nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants and the like.
Among these, as the surfactant, an anionic surfactant or a nonionic surfactant is preferable from the viewpoint of aggregation rate.
　インク組成物が界面活性剤を含む場合、インク組成物中における界面活性剤の含有量は、インクジェット法で良好に打滴することを考慮すると、インク組成物（２５℃）の表面張力を２５ｍＮ／ｍ以上４０ｍＮ／ｍ以下に調整できる量であることが好ましく、２７ｍＮ／ｍ～３７ｍＮ／ｍに調整できる量であることがより好ましい。 In the case where the ink composition contains a surfactant, the surfactant content in the ink composition is determined so that the surface tension of the ink composition (25 ° C.) is 25 mN / It is preferably an amount that can be adjusted to m or more and 40 mN / m or less, and more preferably an amount that can be adjusted to 27 mN / m to 37 mN / m.
　界面活性剤は、消泡剤としても使用することができる。
　界面活性剤としては、フッ素系化合物、シリコーン系化合物、エチレンジアミン四酢酸（ＥＤＴＡ）等のキレート剤なども使用することができる。 Surfactants can also be used as antifoaming agents.
As the surfactant, a fluorine compound, a silicone compound, a chelating agent such as ethylenediaminetetraacetic acid (EDTA), or the like can also be used.
－その他の添加剤－
　インク組成物は、上記の成分以外に、その他の添加剤を更に含むことができる。
　その他の添加剤としては、例えば、褪色防止剤、乳化安定剤、浸透促進剤、紫外線吸収剤、防腐剤、防黴剤、ｐＨ調整剤、消泡剤、粘度調整剤、分散安定剤、防錆剤、キレート剤等の公知の添加剤が挙げられる。
　これらの各種添加剤は、インク組成物を調製した後に直接添加してもよいし、インク組成物を調製する際に添加してもよい。 -Other additives-
The ink composition can further contain other additives in addition to the above components.
Other additives include, for example, antifading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, antiseptics, antifungal agents, pH adjusters, antifoaming agents, viscosity modifiers, dispersion stabilizers, and rust inhibitors. Known additives such as agents and chelating agents are included.
These various additives may be added directly after the ink composition is prepared, or may be added when the ink composition is prepared.
　ｐＨ調整剤としては、中和剤（有機塩基、無機アルカリ等）を用いることができる。
　ｐＨ調整剤は、インク組成物の保存安定性を向上させる観点から、インク組成物（２５℃）のｐＨが６～１０となるように添加することが好ましく、ｐＨが７～１０となるように添加することがより好ましい。 As the pH adjuster, a neutralizing agent (organic base, inorganic alkali, etc.) can be used.
From the viewpoint of improving the storage stability of the ink composition, the pH adjuster is preferably added so that the pH of the ink composition (25 ° C.) is 6 to 10, and the pH is 7 to 10. It is more preferable to add.
～インク組成物の物性～
（ｐＨ）
　インク組成物のｐＨは、インク組成物の保存安定性を向上させる観点から、６～１０が好ましく、７～１０がより好ましい。
　インク組成物のｐＨは、２５℃環境下において、インク組成物を２５℃に調温した状態でｐＨメーターを用いて測定される値である。ｐＨメーターとしては、例えば、東亜ディーケーケー（株）のＷＭ－５０ＥＧを用いることができる。 -Physical properties of ink composition-
(PH)
The pH of the ink composition is preferably 6 to 10 and more preferably 7 to 10 from the viewpoint of improving the storage stability of the ink composition.
The pH of the ink composition is a value measured using a pH meter in a state where the temperature of the ink composition is adjusted to 25 ° C. in an environment of 25 ° C. As the pH meter, for example, WM-50EG manufactured by Toa DK Corporation can be used.
（粘度）
　インク組成物の粘度は、インクジェット法で吐出する場合の吐出安定性、及び、後述の前処理液を用いた際の凝集速度の観点から、１ｍＰａ・ｓ～３０ｍＰａ・ｓの範囲が好ましく、１ｍＰａ・ｓ～２０ｍＰａ・ｓの範囲がより好ましく、２ｍＰａ・ｓ～１５ｍＰａ・ｓの範囲が更に好ましく、２ｍＰａ・ｓ～１０ｍＰａ・ｓの範囲が特に好ましい。
　インク組成物の粘度は、ＶＩＳＣＯＭＥＴＥＲ　ＴＶ－２２（東機産業（株））を用いて、２５℃の条件下で測定されるものである。 (viscosity)
The viscosity of the ink composition is preferably in the range of 1 mPa · s to 30 mPa · s, from the viewpoint of ejection stability when ejected by the ink jet method, and aggregation rate when using a pretreatment liquid described later. The range of s to 20 mPa · s is more preferred, the range of 2 mPa · s to 15 mPa · s is still more preferred, and the range of 2 mPa · s to 10 mPa · s is particularly preferred.
The viscosity of the ink composition is measured at 25 ° C. using VISCOMETER TV-22 (Toki Sangyo Co., Ltd.).
（表面張力）
　インク組成物の表面張力としては、特に制限はなく、例えば、２０ｍＮ／ｍ以上とすることができる。インクジェット法でより良好に打滴するとの観点から、２３ｍＮ／ｍ～４０ｍＮ／ｍが好ましく、２６ｍＮ／ｍ～３７ｍＮ／ｍがより好ましい。
　インク組成物の表面張力は、表面張力計を用い、プレート法により２５℃の条件下で測定される値である。表面張力計としては、例えば、協和界面科学（株）のＡｕｔｏｍａｔｉｃ　Ｓｕｒｆａｃｅ　Ｔｅｎｓｉｏｍｅｔｅｒ　ＣＢＶＰ－Ｚを用いることができる。
　インク組成物の表面張力は、例えば、界面活性剤を添加することで調整することができる。 (surface tension)
The surface tension of the ink composition is not particularly limited and can be, for example, 20 mN / m or more. From the viewpoint of better droplet ejection by the inkjet method, it is preferably 23 mN / m to 40 mN / m, more preferably 26 mN / m to 37 mN / m.
The surface tension of the ink composition is a value measured at 25 ° C. by a plate method using a surface tension meter. As the surface tension meter, for example, Automatic Surface Tensiometer CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. can be used.
The surface tension of the ink composition can be adjusted, for example, by adding a surfactant.
＜前処理液＞
　前処理液は、酸及び水を含み、必要に応じて、更に他の成分を含んでいてもよい。 <Pretreatment liquid>
The pretreatment liquid contains an acid and water, and may further contain other components as necessary.
（酸）
　前処理液は、酸を含む。
　前処理液は、インク組成物に含まれる少なくとも着色剤を凝集させる化合物（凝集化成分）として、酸を含む。
　前処理液が酸を含むと、画像を形成する際に、酸を含む前処理液とインク組成物とを接触させると、酸がインク組成物中の分散成分である少なくとも着色剤に作用して少なくとも着色剤が凝集するため、より鮮鋭な画像を得ることができる。 (acid)
The pretreatment liquid contains an acid.
The pretreatment liquid contains an acid as a compound (aggregating component) that aggregates at least the colorant contained in the ink composition.
When the pretreatment liquid contains an acid, when the pretreatment liquid containing the acid is brought into contact with the ink composition when forming an image, the acid acts on at least the colorant which is a dispersed component in the ink composition. Since at least the colorant aggregates, a sharper image can be obtained.
　酸としては、インク組成物のｐＨを低下させ得る有機酸性化合物及び無機酸性化合物が挙げられる。 Examples of the acid include organic acidic compounds and inorganic acidic compounds that can lower the pH of the ink composition.
　有機酸性化合物としては、特に制限はなく、例えば、リン酸基、ホスホン酸基、ホスフィン酸基、硫酸基、スルホ基、スルフィン酸基、カルボキシ基等を有する化合物が挙げられる。
　これらの中でも、有機酸性化合物としては、インク組成物中の分散成分（少なくとも着色剤）の凝集速度の観点から、リン酸基又はカルボキシ基を有する化合物が好ましく、カルボキシ基を有する化合物がより好ましい。 There is no restriction | limiting in particular as an organic acidic compound, For example, the compound which has a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfo group, a sulfinic acid group, a carboxy group etc. is mentioned.
Among these, as the organic acidic compound, a compound having a phosphate group or a carboxy group is preferable, and a compound having a carboxy group is more preferable from the viewpoint of the aggregation rate of the dispersion component (at least the colorant) in the ink composition.
　カルボキシ基を有する化合物としては、ポリアクリル酸、酢酸、グリコール酸、マロン酸、リンゴ酸（好ましくは、ＤＬ－リンゴ酸）、マレイン酸、アスコルビン酸、コハク酸、グルタル酸、フマル酸、クエン酸、酒石酸、フタル酸、４－メチルフタル酸、乳酸、ピロリドンカルボン酸、ピロンカルボン酸、ピロールカルボン酸、フランカルボン酸、ピリジンカルボン酸、クマリン酸、チオフェンカルボン酸、ニコチン酸、これらの化合物の誘導体、これらの塩（例えば、多価金属塩）等が挙げられる。
　カルボキシ基を有する化合物としては、インク組成物中の分散成分（少なくとも着色剤）の凝集速度の観点から、２価以上のカルボン酸（多価カルボン酸）が好ましく、マロン酸、リンゴ酸、マレイン酸、コハク酸、グルタル酸、フマル酸、酒石酸、４－メチルフタル酸、及びクエン酸からなる群より選ばれる少なくとも１種の多価カルボン酸がより好ましく、マロン酸、リンゴ酸、酒石酸、及びクエン酸からなる群より選ばれる少なくとも１種が特に好ましい。 Examples of the compound having a carboxy group include polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid (preferably DL-malic acid), maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, Tartaric acid, phthalic acid, 4-methylphthalic acid, lactic acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, these Examples thereof include salts (for example, polyvalent metal salts).
The compound having a carboxy group is preferably a divalent or higher carboxylic acid (polyvalent carboxylic acid) from the viewpoint of the aggregation rate of the dispersion component (at least the colorant) in the ink composition, and malonic acid, malic acid, maleic acid. More preferably at least one polycarboxylic acid selected from the group consisting of succinic acid, glutaric acid, fumaric acid, tartaric acid, 4-methylphthalic acid, and citric acid, and malonic acid, malic acid, tartaric acid, and citric acid. Particularly preferred is at least one selected from the group consisting of
　有機酸性化合物は、ｐＫａが低いことが好ましい。カルボキシ基等の弱酸性の官能基により分散安定化しているインク組成物中の顔料、ポリマー粒子等の粒子の表面電荷を、よりｐＫａの低い有機酸性化合物と接触させることにより減じ、分散安定性を低下させることができる。 The organic acidic compound preferably has a low pKa. Dispersion stability is reduced by bringing the surface charge of particles such as pigments and polymer particles in the ink composition stabilized by a weakly acidic functional group such as a carboxy group into contact with an organic acidic compound having a lower pKa. Can be reduced.
　有機酸性化合物としては、ｐＫａが低く、水に対する溶解度が高く、かつ、価数が２価以上である酸性化合物が好ましく、インク組成物中の粒子を分散安定化させている官能基（例えば、カルボキシ基）のｐＫａよりも低いｐＨ領域に高い緩衝能を有する２価又は３価の酸性化合物がより好ましい。 As the organic acidic compound, an acidic compound having a low pKa, a high solubility in water, and a valence of 2 or more is preferable, and a functional group (for example, carboxy group) that stabilizes the particles in the ink composition. A divalent or trivalent acidic compound having a high buffer capacity in a pH range lower than the pKa of the group) is more preferable.
　無機酸性化合物としては、リン酸、リン酸化合物、硝酸、亜硝酸、硫酸、塩酸等が挙げられる。
　これらの中でも、無機酸性化合物としては、画像のざらつき抑制及びインク組成物中の分散成分（少なくとも着色剤）の凝集速度の観点から、リン酸及びリン酸化合物が好ましい。 Examples of inorganic acidic compounds include phosphoric acid, phosphoric acid compounds, nitric acid, nitrous acid, sulfuric acid, hydrochloric acid and the like.
Among these, as the inorganic acidic compound, phosphoric acid and a phosphoric acid compound are preferable from the viewpoint of suppressing the roughness of the image and the aggregation rate of the dispersion component (at least the colorant) in the ink composition.
　リン酸は、カルシウム塩（即ち、リン酸カルシウム）とした際の水への溶解度（２５℃）が０．００１８ｇ／水１００ｇと小さい。したがって、前処理液に含まれる無機酸性化合物がリン酸であると、カルシウム塩が溶解せず固定化され、画像部表面に発生するざらつきを抑制する効果が高い。特に、記録媒体として炭酸カルシウムを含有する塗工層を有する記録媒体を使用した場合には、前処理液に含まれる無機酸性化合物としては、リン酸が有利である。 Phosphoric acid has a low water solubility (25 ° C.) of 0.0018 g / 100 g of water when calcium salt (that is, calcium phosphate) is used. Therefore, when the inorganic acidic compound contained in the pretreatment liquid is phosphoric acid, the calcium salt is not dissolved but immobilized, and the effect of suppressing the roughness generated on the surface of the image area is high. In particular, when a recording medium having a coating layer containing calcium carbonate is used as the recording medium, phosphoric acid is advantageous as the inorganic acidic compound contained in the pretreatment liquid.
　リン酸化合物としては、例えば、亜リン酸、次亜リン酸、ピロリン酸、メタリン酸、ポリリン酸、又はこれらの塩が挙げられる。 Examples of the phosphoric acid compound include phosphorous acid, hypophosphorous acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid, and salts thereof.
　前処理液は、酸を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 The pretreatment liquid may contain only one kind of acid, or may contain two or more kinds.
　前処理液中における酸の含有量は、前処理液の全質量に対して、５質量％～４０質量％が好ましく、１０質量％～３０質量％がより好ましい。
　前処理液中における凝集化成分である酸の含有量が５質量％以上であると、画像のざらつきがより抑制される。
　前処理液中における凝集化成分である酸の含有量が４０質量％以下であると、画像の耐擦性がより向上する。 The acid content in the pretreatment liquid is preferably 5% by mass to 40% by mass and more preferably 10% by mass to 30% by mass with respect to the total mass of the pretreatment liquid.
When the content of the acid as an aggregating component in the pretreatment liquid is 5% by mass or more, the roughness of the image is further suppressed.
When the content of the acid that is an aggregating component in the pretreatment liquid is 40% by mass or less, the abrasion resistance of the image is further improved.
　凝集化成分として有機酸性化合物と無機酸性化合物とを併用する場合、前処理液中における有機酸性化合物と無機酸性化合物との含有比（無機酸性化合物の含有量／有機酸性化合物の含有量）は、インク組成物の凝集速度及び画像のざらつき抑制の観点から、５ｍｏｌ％～５０ｍｏｌ％が好ましく、１０ｍｏｌ％～４０ｍｏｌ％がより好ましく、１５ｍｏｌ％～３５ｍｏｌ％が更に好ましい。 When an organic acidic compound and an inorganic acidic compound are used in combination as an aggregating component, the content ratio of the organic acidic compound and the inorganic acidic compound in the pretreatment liquid (content of inorganic acidic compound / content of organic acidic compound) is: From the viewpoint of the aggregation rate of the ink composition and the suppression of roughness of the image, 5 mol% to 50 mol% is preferable, 10 mol% to 40 mol% is more preferable, and 15 mol% to 35 mol% is still more preferable.
（水）
　前処理液は、水を含み、水性組成物として調製されている。
　水としては、イオン交換水等を用いることができる。
　前処理液中における水の含有量は、特に制限されず、前処理液の全質量に対して、１０質量％～９９質量％が好ましく、５０質量％～９０質量％がより好ましく、６０質量％～８０質量％が更に好ましい。 (water)
The pretreatment liquid contains water and is prepared as an aqueous composition.
As water, ion-exchanged water or the like can be used.
The content of water in the pretreatment liquid is not particularly limited, and is preferably 10% by mass to 99% by mass, more preferably 50% by mass to 90% by mass, and 60% by mass with respect to the total mass of the pretreatment liquid. More preferably, it is 80% by mass.
（他の成分）
　前処理液は、上記の成分以外の他の成分を含んでいてもよい。他の成分としては、例えば、有機溶剤、含窒素ヘテロ環化合物、消泡剤、及びその他の添加剤が挙げられる。 (Other ingredients)
The pretreatment liquid may contain components other than the above components. Examples of other components include organic solvents, nitrogen-containing heterocyclic compounds, antifoaming agents, and other additives.
－有機溶剤－
　前処理液は、有機溶剤を更に含むことが好ましい。
　有機溶剤としては、水溶性有機溶剤が好ましい。
　水溶性有機溶剤としては、既述のインク組成物に含まれ得る水溶性有機溶剤と同様のものが挙げられる。
　前処理液における水溶性有機溶剤としては、カール抑制の観点から、ポリアルキレングリコール又はその誘導体が好ましく、ジエチレングリコールモノアルキルエーテル、トリエチレングリコールモノアルキルエーテル、ジプロピレングリコール、トリプロピレングリコールモノアルキルエーテル、ポリオキシプロピレングリセリルエーテル、及びポリオキシエチレンポリオキシプロピレングリコールからなる群より選ばれる少なくとも１種がより好ましい。 -Organic solvent-
The pretreatment liquid preferably further contains an organic solvent.
As the organic solvent, a water-soluble organic solvent is preferable.
Examples of the water-soluble organic solvent include the same water-soluble organic solvents that can be contained in the ink composition described above.
As the water-soluble organic solvent in the pretreatment liquid, polyalkylene glycol or a derivative thereof is preferable from the viewpoint of curling suppression. Diethylene glycol monoalkyl ether, triethylene glycol monoalkyl ether, dipropylene glycol, tripropylene glycol monoalkyl ether, At least one selected from the group consisting of oxypropylene glyceryl ether and polyoxyethylene polyoxypropylene glycol is more preferable.
　前処理液は、有機溶剤を含む場合、有機溶剤を１種のみ含んでいてもよいし、２種以上含んでいてもよい。 When the pretreatment liquid contains an organic solvent, the pretreatment liquid may contain only one organic solvent or two or more organic solvents.
　前処理液が有機溶剤を含む場合、前処理液中における有機溶剤の含有量としては、特に制限はなく、例えば、カール抑制の観点から、前処理液の全質量に対して、１質量％～３０質量％が好ましく、５質量％～１５質量％がより好ましい。 When the pretreatment liquid contains an organic solvent, the content of the organic solvent in the pretreatment liquid is not particularly limited. For example, from the viewpoint of curling suppression, 1% by mass to 30% by mass is preferable, and 5% by mass to 15% by mass is more preferable.
－含窒素ヘテロ環化合物－
　前処理液は、含窒素ヘテロ環化合物を更に含んでいてもよい。
　前処理液が含窒素ヘテロ環化合物を含むことで、画像の耐擦性が更に向上する。 -Nitrogen-containing heterocyclic compounds-
The pretreatment liquid may further contain a nitrogen-containing heterocyclic compound.
When the pretreatment liquid contains a nitrogen-containing heterocyclic compound, the abrasion resistance of the image is further improved.
　含窒素ヘテロ環化合物のヘテロ環構造としては、含窒素５員環構造又は含窒素６員環構造が好ましく、含窒素５員環構造がより好ましい。
　含窒素５員環構造及び含窒素６員環構造の中でも、炭素原子、窒素原子、酸素原子、硫黄原子及びセレン原子からなる群より選ばれる少なくとも１種の原子を含む５員又は６員のヘテロ環の構造が好ましい。なお、ヘテロ環は、炭素芳香環又は複素芳香環で縮合していてもよい。
　ヘテロ環としては、テトラゾール環、トリアゾール環、イミダゾール環、チアジアゾール環、オキサジアゾール環、セレナジアゾール環、オキサゾール環、チアゾール環、ベンゾオキサゾール環、ベンゾチアゾール環、ベンゾイミダゾール環、ピリミジン環、トリアザインデン環、テトラアザインデン環、ペンタアザインデン環等が挙げられる。 As a heterocyclic structure of a nitrogen-containing heterocyclic compound, a nitrogen-containing 5-membered ring structure or a nitrogen-containing 6-membered ring structure is preferable, and a nitrogen-containing 5-membered ring structure is more preferable.
Among the nitrogen-containing 5-membered ring structure and the nitrogen-containing 6-membered ring structure, a 5-membered or 6-membered heterostructure containing at least one atom selected from the group consisting of a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom A ring structure is preferred. The heterocycle may be condensed with a carbon aromatic ring or a heteroaromatic ring.
Heterocycles include tetrazole, triazole, imidazole, thiadiazole, oxadiazole, selenadiazole, oxazole, thiazole, benzoxazole, benzothiazole, benzimidazole, pyrimidine, and triazaine. Examples include a den ring, a tetraazaindene ring, and a pentaazaindene ring.
　ヘテロ環は、置換基を有してもよい。
　置換基としては、ニトロ基、ハロゲン原子（塩素原子、臭素原子等）、メルカプト基、シアノ基、置換又は無置換のアルキル基（例えば、メチル、エチル、プロピル、ｔ－ブチル、シアノエチル等の各基）、アリール基（例えば、フェニル、４－メタンスルホンアミドフェニル、４－メチルフェニル、３，４－ジクロルフェニル、ナフチル等の各基）、アルケニル基（例えば、アリル基）、アラルキル基（例えば、ベンジル、４－メチルベンジル、フェネチル等の各基）、スルホニル基（例えば、メタンスルホニル、エタンスルホニル、ｐ－トルエンスルホニル等の各基）、カルバモイル基（例えば、無置換カルバモイル、メチルカルバモイル、フェニルカルバモイル等の各基）、スルファモイル基（例えば、無置換スルファモイル、メチルスルファモイル、フェニルスルファモイル等の各基）、カルボンアミド基（例えば、アセトアミド、ベンズアミド等の各基）、スルホンアミド基（例えば、メタンスルホンアミド、ベンゼンスルホンアミド、ｐ－トルエンスルホンアミド等の各基）、アシルオキシ基（例えば、アセチルオキシ、ベンゾイルオキシ等の各基）、スルホニルオキシ基（例えば、メタンスルホニルオキシ基）、ウレイド基（例えば、無置換ウレイド、メチルウレイド、エチルウレイド、フェニルウレイド等の各基）、アシル基（例えば、アセチル、ベンゾイル等の各基）、オキシカルボニル基（例えば、メトキシカルボニル、フェノキシカルボニル等の各基）、オキシカルボニルアミノ基（例えば、メトキシカルボニルアミノ、フェノキシカルボニルアミノ、２－エチルヘキシルオキシカルボニルアミノ等の各基）、ヒドロキシル基などが挙げられる。一つの環に複数の置換基を有していてもよい。 The heterocycle may have a substituent.
Substituents include nitro groups, halogen atoms (chlorine atoms, bromine atoms, etc.), mercapto groups, cyano groups, substituted or unsubstituted alkyl groups (eg, methyl, ethyl, propyl, t-butyl, cyanoethyl groups, etc.) ), Aryl groups (eg, phenyl, 4-methanesulfonamidophenyl, 4-methylphenyl, 3,4-dichlorophenyl, naphthyl, etc.), alkenyl groups (eg, allyl groups), aralkyl groups (eg, Benzyl, 4-methylbenzyl, phenethyl, etc.), sulfonyl groups (eg, methanesulfonyl, ethanesulfonyl, p-toluenesulfonyl, etc.), carbamoyl groups (eg, unsubstituted carbamoyl, methylcarbamoyl, phenylcarbamoyl, etc.) Each group), sulfamoyl group (for example, unsubstituted sulfamoyl, methyl) Rufamoyl, phenylsulfamoyl, etc. groups), carbonamide groups (eg, acetamide, benzamide, etc. groups), sulfonamido groups (eg, methanesulfonamide, benzenesulfonamide, p-toluenesulfonamide, etc.) ), Acyloxy groups (eg, acetyloxy, benzoyloxy, etc.), sulfonyloxy groups (eg, methanesulfonyloxy), ureido groups (eg, unsubstituted ureido, methylureido, ethylureido, phenylureido, etc.) Group), acyl group (for example, each group such as acetyl and benzoyl), oxycarbonyl group (for example, each group such as methoxycarbonyl and phenoxycarbonyl), oxycarbonylamino group (for example, methoxycarbonylamino, phenoxycarbonylamino, 2 - Ethylhexyl each group such butyloxycarbonylamino), such as a hydroxyl group. One ring may have a plurality of substituents.
　含窒素ヘテロ環化合物の好ましい例としては、イミダゾール、ベンゾイミダゾール、ベンゾインダゾール、ベンゾトリアゾール、テトラゾール、ベンゾオキサゾール、ベンゾチアゾール、ピリジン、キノリン、ピリミジン、ピペリジン、ピペラジン、キノキサリン、モルホリン等が挙げられる。これらの含窒素ヘテロ環化合物は、上記のアルキル基、カルボキシ基、スルホ基等の置換基を有していてもよい。 Preferred examples of the nitrogen-containing heterocyclic compound include imidazole, benzimidazole, benzoindazole, benzotriazole, tetrazole, benzoxazole, benzothiazole, pyridine, quinoline, pyrimidine, piperidine, piperazine, quinoxaline, morpholine and the like. These nitrogen-containing heterocyclic compounds may have a substituent such as the above alkyl group, carboxy group, or sulfo group.
　含窒素６員環化合物としては、トリアジン環、ピリミジン環、ピリジン環、ピロリン環、ピペリジン環、ピリダジン環、又はピラジン環を有する化合物が好ましく、トリアジン環又はピリミジン環を有する化合物がより好ましい。
　含窒素６員環化合物は、置換基を有していてもよい。
　置換基としては、炭素数１～６（好ましくは、１～３）のアルキル基、炭素数１～６（好ましくは、１～３）のアルコキシ基、水酸基、カルボキシ基、メルカプト基、炭素数１～６（好ましくは、１～３）のアルコキシアルキル基、炭素数１～６（好ましくは、１～３）のヒドロキシアルキル基等が挙げられる。
　含窒素６員環化合物の好ましい具体例としては、トリアジン、メチルトリアジン、ジメチルトリアジン、ヒドロキシエチルトリアジン環、ピリミジン、４－メチルピリミジン、ピリジン、ピロリン等が挙げられる。 As the nitrogen-containing 6-membered ring compound, a compound having a triazine ring, a pyrimidine ring, a pyridine ring, a pyrroline ring, a piperidine ring, a pyridazine ring or a pyrazine ring is preferable, and a compound having a triazine ring or a pyrimidine ring is more preferable.
The nitrogen-containing 6-membered ring compound may have a substituent.
Examples of the substituent include an alkyl group having 1 to 6 carbon atoms (preferably 1 to 3), an alkoxy group having 1 to 6 carbon atoms (preferably 1 to 3), a hydroxyl group, a carboxy group, a mercapto group, and 1 carbon atom. And an alkoxyalkyl group having 6 to 6 (preferably 1 to 3), a hydroxyalkyl group having 1 to 6 carbon atoms (preferably 1 to 3), and the like.
Preferable specific examples of the nitrogen-containing 6-membered ring compound include triazine, methyltriazine, dimethyltriazine, hydroxyethyltriazine ring, pyrimidine, 4-methylpyrimidine, pyridine, pyrroline and the like.
－消泡剤－
　前処理液は、消泡剤を含んでいてもよい。
　消泡剤としては、シリコーン系化合物（即ち、シリコーン系消泡剤）、プルロニック系化合物（即ち、プルロニック系消泡剤）等が挙げられる。
　これらの中でも、消泡剤としては、シリコーン系消泡剤が好ましい。
　シリコーン系消泡剤としては、ポリシロキサン構造を有するシリコーン系消泡剤が好ましい。 -Antifoaming agent-
The pretreatment liquid may contain an antifoaming agent.
Examples of the antifoaming agent include silicone compounds (that is, silicone antifoaming agents) and pluronic compounds (that is, pluronic antifoaming agents).
Among these, as an antifoamer, a silicone type antifoamer is preferable.
As the silicone-based antifoaming agent, a silicone-based antifoaming agent having a polysiloxane structure is preferable.
　消泡剤としては、上市されている市販品を用いてもよい。
　消泡剤の市販品の例としては、ＢＹＫ－０１２、ＢＹＫ－０１７、ＢＹＫ－０２１、ＢＹＫ－０２２、ＢＹＫ－０２４、ＢＹＫ－０２５、ＢＹＫ－０３８、ＢＹＫ－０９４（以上、ビックケミー・ジャパン（株））、ＫＳ－５３７、ＫＳ－６０４、ＫＭ－７２Ｆ（以上、信越化学工業（株））、ＴＳＡ－７３９（モメンティブ・パフォーマンス・マテリアルズ・ジャパン合同会社）、オルフィン（登録商標）ＡＦ１０４（日信化学工業（株））等が挙げられる。
　これらの中でも、消泡剤としては、シリコーン系消泡剤である、ＢＹＫ－０１７、ＢＹＫ－０２１、ＢＹＫ－０２２、ＢＹＫ－０２４、ＢＹＫ－０２５、ＢＹＫ－０９４、ＫＳ－５３７、ＫＳ－６０４、ＫＭ－７２Ｆ、及びＴＳＡ－７３９からなる群より選ばれる少なくとも１種が好ましく、インク組成物の吐出安定性の観点からは、ＢＹＫ－０２４が特に好ましい。 As a defoaming agent, a commercially available product may be used.
Examples of commercially available antifoaming agents include BYK-012, BYK-017, BYK-021, BYK-022, BYK-024, BYK-025, BYK-038, BYK-094 (above, BYK Chemie Japan, Inc. )), KS-537, KS-604, KM-72F (Shin-Etsu Chemical Co., Ltd.), TSA-739 (Momentive Performance Materials Japan GK), Olfin (registered trademark) AF104 (Nissin) Chemical Industry Co., Ltd.).
Among these, as the antifoaming agent, silicone-based antifoaming agents such as BYK-017, BYK-021, BYK-022, BYK-024, BYK-025, BYK-094, KS-537, KS-604, At least one selected from the group consisting of KM-72F and TSA-739 is preferred, and BYK-024 is particularly preferred from the viewpoint of ejection stability of the ink composition.
　前処理液が消泡剤を含む場合、前処理液中における消泡剤の含有量は、前処理液の全質量に対して、０．０００１質量％～１質量％が好ましく、０．００１質量％～０．１質量％がより好ましい。
　消泡剤としてシリコーン系消泡剤を用いる場合には、シリコーンオイル量が０．００５質量％～０．０２質量％となる量を含むことが好ましい。 When the pretreatment liquid contains an antifoaming agent, the content of the antifoaming agent in the pretreatment liquid is preferably 0.0001% by mass to 1% by mass, and 0.001% by mass with respect to the total mass of the pretreatment liquid. % To 0.1% by mass is more preferable.
When a silicone-based antifoaming agent is used as the antifoaming agent, it is preferable that the amount of the silicone oil is 0.005% by mass to 0.02% by mass.
－水不溶性樹脂の粒子－
　前処理液は、水不溶性樹脂の粒子を含むことができる。
　前処理液が水不溶性樹脂の粒子を含むことで、前処理液付与後の被記録材料の表面に水不溶性樹脂の粒子の大部分が偏在し、被記録材料の表面の濡れ性が改善される。
　水不溶性樹脂の粒子が表面に偏在した被記録材料にインク組成物が着滴すると、インク滴が被記録材料の表面で濡れ広がり、かつ、前処理液に含まれる凝集化成分（即ち、酸）がインク組成物中の分散成分（例えば、着色剤）を凝集させる。これにより、液滴同士の合一が防止され、かつ、液滴サイズが所望とする大きさになる。その結果、ベタ画像部の濃度低下が抑制され、所望とする濃度を有するベタ画像部が得られる。
　また、前処理液が水不溶性樹脂の粒子を含むことで、記録画像中に生じやすい筋状のムラの発生が抑制される。更に、画像中のざらつきも抑制することができる。
　なお、「ざらつき（ｇｒａｉｎｉｎｅｓｓ）」とは、インク組成物が被記録材料に着滴した後、液滴同士が合一することで、画像中に微小な濃度ムラが発生し、画素の均一性が低下する現象をいう。 -Water-insoluble resin particles-
The pretreatment liquid may contain water-insoluble resin particles.
By including the water-insoluble resin particles in the pretreatment liquid, most of the water-insoluble resin particles are unevenly distributed on the surface of the recording material after the pretreatment liquid is applied, and the wettability of the surface of the recording material is improved. .
When the ink composition deposits on the recording material in which water-insoluble resin particles are unevenly distributed on the surface, the ink droplet spreads on the surface of the recording material, and an aggregating component (ie, acid) contained in the pretreatment liquid Agglomerates dispersed components (for example, colorants) in the ink composition. As a result, the droplets are prevented from coalescing, and the droplet size becomes a desired size. As a result, a decrease in density of the solid image portion is suppressed, and a solid image portion having a desired density is obtained.
In addition, since the pretreatment liquid contains water-insoluble resin particles, the occurrence of streak-like unevenness that tends to occur in the recorded image is suppressed. Furthermore, roughness in the image can also be suppressed.
Note that “graininess” means that after the ink composition has landed on the recording material, the droplets coalesce, causing minute density unevenness in the image and pixel uniformity. A phenomenon that decreases.
　水不溶性樹脂の「水不溶性」については、既述のオーバーコート液に含まれる「樹脂の粒子」における樹脂（水不溶性樹脂）の「水不溶性」と同義である。すなわち、既述のオーバーコート液の項において定義した「非水溶性又は難水溶性」と同義である。
　水不溶性樹脂の粒子における水不溶性樹脂は、スルホ基及びスルホ基の塩から選ばれる少なくとも一つの基を含む単量体に由来の構成単位と、芳香環構造を含む単量体に由来の構成単位と、を少なくとも有していることが好ましく、必要に応じて、更に、他の単量体に由来の構成単位を有していてもよい。 The “water-insoluble” of the water-insoluble resin is synonymous with the “water-insoluble” of the resin (water-insoluble resin) in the “resin particles” contained in the above-described overcoat liquid. That is, it is synonymous with “water-insoluble or poorly water-soluble” defined in the above-mentioned section of the overcoat solution.
The water-insoluble resin in the water-insoluble resin particles includes a structural unit derived from a monomer containing at least one group selected from a sulfo group and a salt of the sulfo group, and a structural unit derived from a monomer containing an aromatic ring structure. It is preferable to have at least, and if necessary, it may further have structural units derived from other monomers.
　スルホ基及びスルホ基の塩から選ばれる少なくとも一つの基を有する単量体に由来する構成単位としては、例えば、アクリルアミド－２－メチルプロパンスルホン酸、アクリルアミド－２－メチルプロパンスルホン酸の塩、スチレンスルホン酸、α－メチルスチレンスルホン酸、３－スルホプロピル（メタ）アクリレート等に由来する構成単位が挙げられる。塩における対イオンは、Ｎａイオン、Ｋイオン、Ｌｉイオン、又はＡｌイオンが好ましい。
　これらの中でも、スルホ基及びスルホ基の塩から選ばれる少なくとも一つの基を有する単量体に由来する構成単位としては、アクリルアミド－２－メチルプロパンスルホン酸に由来する構成単位が好ましい。
　芳香環構造を含む単量体に由来の構成単位としては、スチレンに由来の構成単位が好ましい。
　他の単量体に由来の構成単位としては、アクリル酸エステル系単量体に由来の構成単位が好ましい。 Examples of the structural unit derived from a monomer having at least one group selected from a sulfo group and a salt of a sulfo group include acrylamide-2-methylpropanesulfonic acid, acrylamide-2-methylpropanesulfonic acid salt, styrene Examples include structural units derived from sulfonic acid, α-methylstyrene sulfonic acid, 3-sulfopropyl (meth) acrylate, and the like. The counter ion in the salt is preferably Na ion, K ion, Li ion, or Al ion.
Among these, as the structural unit derived from a monomer having at least one group selected from a sulfo group and a salt of a sulfo group, a structural unit derived from acrylamide-2-methylpropanesulfonic acid is preferable.
As a structural unit derived from a monomer containing an aromatic ring structure, a structural unit derived from styrene is preferable.
As the structural unit derived from another monomer, a structural unit derived from an acrylate ester monomer is preferable.
　粒子を構成する水不溶性樹脂の重量平均分子量（Ｍｗ）は、３，０００～１５０，０００であることが好ましい。
　水不溶性樹脂の重量平均分子量（Ｍｗ）を３，０００以上とすることで、前処理液の保存安定性が良好となる。
　水不溶性樹脂の重量平均分子量（Ｍｗ）を１５０，０００以下とすることで、前処理液を塗布した後の被記録材料の表面に、指紋痕が残り難くなり、取り扱い性が良好となる。
　なお、前処理液に含まれ得る水不溶性樹脂の重量平均分子量（Ｍｗ）は、既述のオーバーコート液に含まれる水不溶性樹脂の重量平均分子量（Ｍｗ）の測定と同様の方法により測定される値である。 The water-insoluble resin constituting the particles preferably has a weight average molecular weight (Mw) of 3,000 to 150,000.
By setting the weight average molecular weight (Mw) of the water-insoluble resin to 3,000 or more, the storage stability of the pretreatment liquid is improved.
By setting the weight average molecular weight (Mw) of the water-insoluble resin to 150,000 or less, fingerprint marks are hardly left on the surface of the recording material after the pretreatment liquid is applied, and the handleability is improved.
The weight average molecular weight (Mw) of the water-insoluble resin that can be contained in the pretreatment liquid is measured by the same method as the measurement of the weight average molecular weight (Mw) of the water-insoluble resin contained in the overcoat liquid described above. Value.
　粒子を構成する水不溶性樹脂のガラス転移温度（Ｔｇ）は、４０℃以上１２０℃であることが好ましい。
　水不溶性樹脂のＴｇが４０℃以上であると、前処理液の保存安定性が良好となる。
　水不溶性樹脂のＴｇが１２０℃以下であると、前処理液を塗布した前後での被記録材料の風合いの変化が少なくなる。
　水不溶性樹脂のＴｇは、既述のオーバーコート液に含まれる水不溶性樹脂のＴｇの測定と同様の方法により測定される値である。 The glass transition temperature (Tg) of the water-insoluble resin constituting the particles is preferably 40 ° C. or higher and 120 ° C.
When the Tg of the water-insoluble resin is 40 ° C. or higher, the storage stability of the pretreatment liquid is good.
When the Tg of the water-insoluble resin is 120 ° C. or less, the change in the texture of the recording material before and after the pretreatment liquid is applied is reduced.
The Tg of the water-insoluble resin is a value measured by the same method as the measurement of the Tg of the water-insoluble resin contained in the overcoat liquid described above.
　水不溶性樹脂の粒子の平均粒子径は、体積平均粒子径で１０ｎｍ～３００ｎｍが好ましく、１５ｎｍ～１５０ｎｍがより好ましい。
　水不溶性樹脂の粒子の体積平均粒子径が１０ｎｍ以上であると、前処理液の保存安定性が良好となる。
　水不溶性樹脂の粒子の体積平均粒子径が３００ｎｍ以下であると、前処理液を塗布した前後での被記録材料の風合いの変化が少なくなる。
　水不溶性樹脂の粒子の粒径分布に関しては、特に制限はなく、広い粒径分布又は単分散性の粒径分布のいずれであってもよい。また、単分散性の粒径分布を持つ水不溶性樹脂の粒子を２種以上混合して使用してもよい。
　なお、水不溶性樹脂の粒子の平均粒子径及び粒径分布は、ナノトラック粒度分布測定装置を用いて、動的光散乱法により体積平均粒径を測定することで求められるものである。ナノトラック粒度分布測定装置としては、例えば、日機装（株）のＵＰＡ－ＥＸ１５０を用いることができる。 The average particle size of the water-insoluble resin particles is preferably 10 nm to 300 nm, more preferably 15 nm to 150 nm in terms of volume average particle size.
When the volume average particle size of the water-insoluble resin particles is 10 nm or more, the storage stability of the pretreatment liquid is improved.
When the volume average particle diameter of the water-insoluble resin particles is 300 nm or less, the change in the texture of the recording material before and after the pretreatment liquid is applied is reduced.
The particle size distribution of the water-insoluble resin particles is not particularly limited, and may be either a wide particle size distribution or a monodisperse particle size distribution. Further, two or more kinds of water-insoluble resin particles having a monodisperse particle size distribution may be mixed and used.
The average particle size and particle size distribution of the water-insoluble resin particles are determined by measuring the volume average particle size by a dynamic light scattering method using a nanotrack particle size distribution measuring device. As the nanotrack particle size distribution measuring apparatus, for example, UPA-EX150 manufactured by Nikkiso Co., Ltd. can be used.
－その他の添加剤－
　前処理液は、上記の成分以外に、その他の添加剤を更に含むことができる。
　その他の添加剤としては、既述のインク組成物におけるその他の添加剤と同様である。 -Other additives-
The pretreatment liquid can further contain other additives in addition to the above components.
Other additives are the same as other additives in the ink composition described above.
～前処理液の物性～
（ｐＨ）
　前処理液のｐＨは、インク組成物の凝集速度の観点から、７．０以下が好ましく、０．５～３．５がより好ましく、０．５～２．０が更に好ましい。
　前処理液のｐＨは、２５℃環境下において、前処理液を２５℃に調温した状態でｐＨメーターを用いて測定される値である。ｐＨメーターとしては、例えば、東亜ディーケーケー（株）のＷＭ－５０ＥＧを用いることができる。 ~ Physical properties of pretreatment liquid ~
(PH)
The pH of the pretreatment liquid is preferably 7.0 or less, more preferably 0.5 to 3.5, and still more preferably 0.5 to 2.0 from the viewpoint of the aggregation rate of the ink composition.
The pH of the pretreatment liquid is a value measured using a pH meter in a state where the temperature of the pretreatment liquid is adjusted to 25 ° C in an environment of 25 ° C. As the pH meter, for example, WM-50EG manufactured by Toa DK Corporation can be used.
（表面張力）
　前処理液の表面張力としては、特に制限はなく、例えば、２０ｍＮ／ｍ以上とすることができる。被記録材料に対する塗布性の観点から、２０ｍＮ／ｍ～６０ｍＮ／ｍが好ましく、２５ｍＮ／ｍ～４５ｍＮ／ｍがより好ましい。
　前処理液の表面張力は、表面張力計を用い、プレート法により２５℃の条件下で測定される値である。表面張力計としては、例えば、協和界面科学（株）のＡｕｔｏｍａｔｉｃ　Ｓｕｒｆａｃｅ　Ｔｅｎｓｉｏｍｅｔｅｒ　ＣＢＶＰ－Ｚを用いることができる。
　前処理液の表面張力は、例えば、界面活性剤を添加することで調整することができる。 (surface tension)
There is no restriction | limiting in particular as surface tension of a pretreatment liquid, For example, it can be set to 20 mN / m or more. From the viewpoint of applicability to the recording material, 20 mN / m to 60 mN / m is preferable, and 25 mN / m to 45 mN / m is more preferable.
The surface tension of the pretreatment liquid is a value measured at 25 ° C. by a plate method using a surface tension meter. As the surface tension meter, for example, Automatic Surface Tensiometer CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. can be used.
The surface tension of the pretreatment liquid can be adjusted, for example, by adding a surfactant.
（粘度）
　前処理液の粘度は、インク組成物の凝集速度の観点から、１ｍＰａ・ｓ～３０ｍＰａ・ｓが好ましく、１ｍＰａ・ｓ～２０ｍＰａ・ｓがより好ましく、２ｍＰａ・ｓ～１５ｍＰａ・ｓが更に好ましく、２ｍＰａ・ｓ～１０ｍＰａ・ｓが特に好ましい。
　前処理液の粘度は、ＶＩＳＣＯＭＥＴＥＲ　ＴＶ－２２（東機産業（株））を用いて２５℃の条件下で測定される値である。 (viscosity)
The viscosity of the pretreatment liquid is preferably 1 mPa · s to 30 mPa · s, more preferably 1 mPa · s to 20 mPa · s, further preferably 2 mPa · s to 15 mPa · s, from the viewpoint of the aggregation rate of the ink composition. • s to 10 mPa · s is particularly preferable.
The viscosity of the pretreatment liquid is a value measured under the condition of 25 ° C. using VISCOMETER TV-22 (Toki Sangyo Co., Ltd.).
　以上、本開示のインクセットについて説明したが、本開示のインクセットは、既述のオーバーコート液の少なくとも１種と、既述のインク組成物の少なくとも１種と、既述の前処理液の少なくとも１種と、を含む態様であればよく、更に他の液を含んでもよい。 Although the ink set of the present disclosure has been described above, the ink set of the present disclosure includes at least one overcoat liquid described above, at least one ink composition described above, and a pretreatment liquid described above. As long as it contains at least one kind, another liquid may be included.
［画像形成方法］
　本開示の画像形成方法は、被記録材料に、酸及び水を含む前処理液を付与する工程（以下、「前処理工程」ともいう。）と、被記録材料の前処理液の付与面に、着色剤及び水を含むインク組成物を付与して画像を形成する工程（以下、「画像形成工程」ともいう。）と、被記録材料の画像が形成された側の少なくとも一部に、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子、及び水を含むオーバーコート液を付与する工程（以下、「オーバーコート工程」ともいう。）と、を有する。
　本開示の画像形成方法は、必要に応じて、前処理工程、画像形成工程、及びオーバーコート工程以外の他の工程を有していてもよい。
　本開示の画像形成方法では、画像形成にあたって既述のインクセットが用いられ、画像上をオーバーコートするので、酸含有処理液を用いて画像を形成する場合にも、画像形成面の光沢性が良好となる。
　以下、本開示の画像形成方法における各工程について説明する。なお、インク組成物、前処理液、インク組成物、及びオーバーコート液の詳細、並びに好ましい態様については、インクセットの項にて詳述したので、ここでは説明を省略する。 [Image forming method]
The image forming method of the present disclosure includes a step of applying a pretreatment liquid containing acid and water to a recording material (hereinafter also referred to as a “pretreatment step”), and a pretreatment liquid application surface of the recording material. A step of forming an image by applying an ink composition containing a colorant and water (hereinafter also referred to as an “image forming step”), and at least a part of the recording material on which the image is formed. A step of applying an overcoat solution containing the resin particles having a group represented by (1) and having no carboxy group, and water (hereinafter also referred to as “overcoat step”). Have.
The image forming method of the present disclosure may include processes other than the pretreatment process, the image forming process, and the overcoat process as necessary.
In the image forming method of the present disclosure, the above-described ink set is used for image formation, and the image is overcoated. Therefore, even when an image is formed using an acid-containing treatment liquid, the glossiness of the image forming surface is high. It becomes good.
Hereinafter, each step in the image forming method of the present disclosure will be described. The details of the ink composition, the pretreatment liquid, the ink composition, and the overcoat liquid, as well as the preferred embodiments, have been described in detail in the section of the ink set, and thus the description thereof is omitted here.
　被記録材料としては、表面に水滴を付与して３秒経過したときの接触角（水接触角）が７０°以上である基材が好適である。
　被記録材料の例としては、塗工紙、合成紙等の紙基材、ポリエチレンテレフタレート（ＰＥＴ）フィルム等のポリマー基材などが挙げられる。
　これらの中でも、被記録材料としては、ベタ画像部の濃度低下と筋状のムラ（及び場合によりざらつき）とを抑制する効果が顕著に現れる点で、紙基材が好ましく、塗工層を有する紙基材（所謂、塗工紙）がより好ましい。 As the recording material, a substrate having a contact angle (water contact angle) of 70 ° or more when 3 seconds have passed since a water droplet was applied to the surface is suitable.
Examples of the recording material include paper base materials such as coated paper and synthetic paper, and polymer base materials such as polyethylene terephthalate (PET) film.
Among these, as the recording material, a paper base material is preferable and has a coating layer in that the effect of suppressing density reduction and streaky unevenness (and roughness in some cases) in the solid image portion appears remarkably. A paper base material (so-called coated paper) is more preferable.
　被記録材料の表面における水との接触角は、接触角計（製品名：ドロップマスターＤＭ７００、協和界面科学（株））を用い、日本工業規格（ＪＩＳ　Ｒ３２５７）に記載の方法に準拠して、常温常湿下で測定される。 The contact angle with water on the surface of the recording material is determined according to the method described in Japanese Industrial Standard (JIS R3257) using a contact angle meter (product name: Dropmaster DM700, Kyowa Interface Science Co., Ltd.) Measured at room temperature and humidity.
　塗工紙は、支持体となるセルロースを主体とした一般に表面処理されていない上質紙又は中性紙の表面に、無機顔料等を含む塗工層を設けたものである。塗工紙は、画像部の光沢ムラが発生しやすい傾向があるが、前処理液にリン酸又はリン酸化合物が含まれる場合には、画像部の光沢ムラの発生を効果的に抑制することができる。塗工紙としては、具体的には、アート紙、コート紙、軽量コート紙、又は微塗工紙が好ましい。 The coated paper is one in which a coating layer containing an inorganic pigment or the like is provided on the surface of high-quality paper or neutral paper that is generally not surface-treated and mainly comprises cellulose as a support. Coated paper tends to cause uneven gloss in the image area, but effectively suppresses uneven gloss in the image area when the pretreatment liquid contains phosphoric acid or a phosphoric acid compound. Can do. Specifically, the coated paper is preferably art paper, coated paper, lightweight coated paper, or fine coated paper.
　塗工層に含まれる無機顔料としては、特に制限はないが、例えば、シリカ、カオリン、クレー、焼成クレー、酸化亜鉛、酸化錫、硫酸マグネシウム、酸化アルミニウム、水酸化アルミニウム、擬ベーマイト、炭酸カルシウム、サチンホワイト、珪酸アルミニウム、スメクタイト、ゼオライト、珪酸マグネシウム、炭酸マグネシウム、酸化マグネシウム、及び珪藻土からなる群より選ばれる少なくとも１種であることが好ましく、炭酸カルシウム、シリカ、及びカオリンからなる群より選ばれる少なくとも１種がより好ましい。 The inorganic pigment contained in the coating layer is not particularly limited, for example, silica, kaolin, clay, calcined clay, zinc oxide, tin oxide, magnesium sulfate, aluminum oxide, aluminum hydroxide, pseudoboehmite, calcium carbonate, It is preferably at least one selected from the group consisting of satin white, aluminum silicate, smectite, zeolite, magnesium silicate, magnesium carbonate, magnesium oxide, and diatomaceous earth, and at least selected from the group consisting of calcium carbonate, silica, and kaolin. One type is more preferable.
　被記録材料としては、上市されている市販品を用いることができる。
　被記録材料の市販品の例としては、王子製紙（株）の「ボンアイボリー」、Ｓａｐｐｉ社の「ＭａｇｎｏＳｔａｒＧｌｏｓｓ」、Ｉｎｔｅｒｎａｔｉｏｎａｌ社の「ＣａｒｏｌｉｎａＣ２Ｓ」、Ｍｅｔｓａｂｏａｒｄ社の「ＣａｒｔａＩｎｔｅｇｒａ」、ＹＵＰＯ社の「ＶＪＦＰシリーズ」等が挙げられる。 As the recording material, a commercially available product can be used.
Examples of commercially available recording materials include “Bon Ivory” from Oji Paper Co., Ltd., “MagnoStarGloss” from Sappi, “Carolina C2S” from International, “CartaIntegra” from Metsaboard, “VJFP series” from YUPO. Etc.
　前処理液の付与量及びインク組成物の付与量は、必要に応じて調節されることが好ましい。例えば、被記録材料に応じて、前処理液とインク組成物とが混合してできる凝集物の粘弾性等の物性を調節するために、前処理液の付与量を変えてもよい。 It is preferable that the application amount of the pretreatment liquid and the application amount of the ink composition are adjusted as necessary. For example, the amount of the pretreatment liquid applied may be changed in order to adjust the physical properties such as the viscoelasticity of the aggregate formed by mixing the pretreatment liquid and the ink composition according to the recording material.
－前処理工程－
　前処理工程では、被記録材料に、酸及び水を含む前処理液を付与する。
　前処理液の付与は、塗布法、インクジェット法、浸漬法等の公知の方法により行うことができる。
　塗布法としては、バーコーター、エクストルージョンダイコーター、エアードクターコーター、ブレードコーター、ロッドコーター、ナイフコーター、スクイズコーター、リバースロールコーター、バーコーター等を用いた公知の塗布法が挙げられる。
　インクジェット法の詳細については後述する。 -Pretreatment process-
In the pretreatment step, a pretreatment liquid containing acid and water is applied to the recording material.
The pretreatment liquid can be applied by a known method such as a coating method, an ink jet method, or an immersion method.
Examples of the coating method include known coating methods using a bar coater, an extrusion die coater, an air doctor coater, a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, a bar coater and the like.
Details of the inkjet method will be described later.
　前処理工程は、インク組成物を用いた画像形成工程前に設けられる。すなわち、被記録材料上にインク組成物を付与する前に、あらかじめインク組成物中の分散成分（着色剤等）を凝集させるための前処理液を付与しておき、被記録材料上に付与された前処理液に接触するようにインク組成物を付与して画像化する。これにより、インクジェット記録を高速化することができ、高速記録しても濃度及び解像度の高い精細な画像が得られる。 The pretreatment process is provided before the image forming process using the ink composition. That is, before applying the ink composition onto the recording material, a pretreatment liquid for aggregating the dispersion components (colorant, etc.) in the ink composition is applied in advance, and then applied onto the recording material. The ink composition is applied so as to come into contact with the pretreatment liquid, and an image is formed. Thereby, inkjet recording can be speeded up, and a fine image with high density and resolution can be obtained even at high speed recording.
　また、被記録材料上の前処理液は、前処理液を被記録材料上に付与した後、インク組成物が付与されるまでの間に、加熱乾燥されることが好ましい。これにより、滲みが防止され、インク着色性が良好になり、色濃度及び色相の良好な可視画像を記録することができる。 The pretreatment liquid on the recording material is preferably heat-dried after the pretreatment liquid is applied onto the recording material and before the ink composition is applied. Accordingly, bleeding is prevented, ink colorability is improved, and a visible image having good color density and hue can be recorded.
　加熱乾燥は、ヒーター等の公知の加熱手段、ドライヤー等の送風を利用した送風手段、又は公知の加熱手段と送風手段とを組み合わせた手段により行える。
　加熱方法としては、例えば、被記録材料の前処理液が付与された側と反対側からヒーター等で熱を与える方法、被記録材料の前処理液が付与された側に温風又は熱風をあてる方法、又は赤外線ヒーターを用いて加熱する方法が挙げられる。加熱は、これらの加熱方法を複数組み合わせて行ってもよい。 Heating and drying can be performed by a known heating means such as a heater, a blowing means using blowing air such as a dryer, or a combination of a known heating means and a blowing means.
As a heating method, for example, a method of applying heat with a heater or the like from the side opposite to the side to which the pretreatment liquid of the recording material is applied, or hot air or hot air is applied to the side of the recording material to which the pretreatment liquid has been applied. The method or the method of heating using an infrared heater is mentioned. Heating may be performed by combining a plurality of these heating methods.
－画像形成工程－
　画像形成工程では、被記録材料の前処理液の付与面に、着色剤及び水を含むインク組成物を付与して画像を形成する。 -Image formation process-
In the image forming step, an image is formed by applying an ink composition containing a colorant and water to the application surface of the pretreatment liquid of the recording material.
　インクジェット法は、特に制限されず、例えば、静電誘引力を利用してインクを吐出させる電荷制御方式、ピエゾ素子の振動圧力を利用するドロップオンデマンド方式（圧力パルス方式）、電気信号を音響ビームに変えインクに照射して放射圧を利用してインクを吐出させる音響インクジェット方式、及びインクを加熱して気泡を形成し、生じた圧力を利用するサーマルインクジェット（バブルジェット（登録商標））方式のいずれであってもよい。
　インクジェット法としては、特に、特開昭５４－５９９３６号公報に記載の方法、即ち、熱エネルギーの作用を受けたインクが急激な体積変化を生じ、この状態変化による作用力によって、インクをノズルから吐出させるインクジェット法を有効に利用することができる。
　なお、インクジェット法には、フォトインクと称する濃度の低いインクを小さい体積で多数射出する方式、実質的に同じ色相で濃度の異なる複数のインクを用いて画質を改良する方式、及び無色透明のインクを用いる方式が含まれる。 The ink jet method is not particularly limited. For example, a charge control method that ejects ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that uses vibration pressure of a piezoelectric element, and an electric signal as an acoustic beam. Instead of acoustic ink jet method that uses ink to irradiate ink and ejects ink using radiation pressure, and thermal ink jet method (bubble jet (registered trademark)) method that uses ink to form bubbles by heating ink Either may be sufficient.
As the ink jet method, in particular, the method described in Japanese Patent Application Laid-Open No. 54-59936, that is, the ink subjected to the action of heat energy causes a sudden volume change, and the ink is discharged from the nozzle by the action force due to this state change. The ink jet method for discharging can be used effectively.
The inkjet method includes a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method using is included.
　インクジェット法で用いるインクジェットヘッドは、オンデマンド方式であってもよいし、コンティニュアス方式であってもよい。
　吐出方式としては、電気－機械変換方式（シングルキャビティー型、ダブルキャビティー型、ベンダー型、ピストン型、シェアーモード型、シェアードウォール型等）、電気－熱変換方式（サーマルインクジェット型、バブルジェット（登録商標）型等）、静電吸引方式（電界制御型、スリットジェット型等）、放電方式（スパークジェット型等）などが挙げられ、これらの吐出方式のいずれを用いてもよい。
　インクジェット法により記録を行う際に使用するインクノズルについては、特に制限はなく、目的に応じて、適宜選択することができる。 An ink jet head used in the ink jet method may be an on-demand method or a continuous method.
Discharge methods include electro-mechanical conversion methods (single cavity type, double cavity type, bender type, piston type, shear mode type, shared wall type, etc.), electro-thermal conversion methods (thermal ink jet type, bubble jet ( (Registered trademark) type), electrostatic attraction method (electric field control type, slit jet type, etc.), discharge method (spark jet type, etc.), and any of these discharge methods may be used.
There are no particular limitations on the ink nozzles used when recording by the inkjet method, and they can be selected as appropriate according to the purpose.
　インクジェットヘッドとしては、単尺のシリアルヘッドを用い、ヘッドを被記録材料の幅方向に走査させながら記録を行なうシャトル方式と、被記録材料の１辺の全域に対応して記録素子が配列されているラインヘッドを用いたライン方式とがある。
　ライン方式では、記録素子の配列方向と直交する方向に被記録材料を走査させることで、被記録材料の全面に画像を形成することができ、短尺ヘッドを走査するキャリッジ等の搬送系が不要となる。また、キャリッジの移動と被記録材料との複雑な走査制御が不要になり、被記録材料だけが移動するので、シャトル方式に比べて記録速度の高速化が実現できる。 As an ink jet head, a single serial head is used, and a shuttle system that performs recording while scanning the head in the width direction of the recording material, and recording elements are arranged corresponding to the entire area of one side of the recording material. There is a line system using a line head.
In the line method, an image can be formed on the entire surface of the recording material by scanning the recording material in a direction orthogonal to the arrangement direction of the recording elements, and a carriage system such as a carriage for scanning a short head is unnecessary. Become. Further, since complicated scanning control of the carriage movement and the recording material is not required, and only the recording material moves, the recording speed can be increased as compared with the shuttle system.
　画像形成工程は、前処理工程の後、１０秒以内に開始されることが好ましく、０．１秒以上１０秒以内に開始されることがより好ましい。これにより、高速に画像を形成することができる。「前処理工程の後、１０秒以内に開始」とは、前処理液の付与及び乾燥終了から、最初のインク滴が被記録材料上に着滴するまでの時間が１０秒以内であることを意味する。 The image forming step is preferably started within 10 seconds after the preprocessing step, and more preferably within 0.1 seconds to 10 seconds. Thereby, an image can be formed at high speed. “Start within 10 seconds after the pretreatment step” means that the time from the application of the pretreatment liquid and the completion of drying to the first ink droplet landing on the recording material is within 10 seconds. means.
　画像形成工程では、高精細印画の観点から、付与（打滴）されるインク滴の液滴量が、１．５ｐＬ（ピコリットル）～３．０ｐＬであることが好ましく、１．５ｐＬ～２．５ｐＬであることがより好ましい。
　なお、インク滴の液滴量は、打滴するインク組成物に応じて、インクジェット法における吐出条件を適宜選択することで調整することができる。 In the image forming step, from the viewpoint of high-definition printing, the amount of ink droplets to be applied (droplet ejection) is preferably 1.5 pL (picoliter) to 3.0 pL, and preferably 1.5 pL to 2. More preferably, it is 5 pL.
The amount of ink droplets can be adjusted by appropriately selecting the ejection conditions in the ink jet method according to the ink composition to be ejected.
－加熱定着工程－
　本開示の画像形成方法では、前処理工程及び画像形成工程を経て記録された画像を加熱定着する加熱定着工程を更に有していてもよい。
　加熱定着工程によれば、被記録材料上の画像の定着が施され、画像の耐擦性がより向上する。 -Heat fixing process-
The image forming method of the present disclosure may further include a heat fixing step of heat fixing the image recorded through the preprocessing step and the image forming step.
According to the heat fixing step, the image on the recording material is fixed, and the abrasion resistance of the image is further improved.
　インク組成物が樹脂粒子を含む場合、加熱定着工程における加熱は、画像中の樹脂粒子の最低造膜温度（ＭＦＴ：Minimum Film-forming Temperature）以上の温度で行うことが好ましい。ＭＦＴ以上に加熱されることで、樹脂粒子が皮膜化して画像の耐擦性が向上する。
　加熱加圧する場合、加圧時における圧力は、表面平滑化の点で、０．１ＭＰａ～３．０ＭＰａが好ましく、０．１ＭＰａ～１．０ＭＰａがより好ましく、０．１ＭＰａ～０．５ＭＰａが更に好ましい。 When the ink composition contains resin particles, the heating in the heat fixing step is preferably performed at a temperature equal to or higher than the minimum film-forming temperature (MFT) of the resin particles in the image. By heating to MFT or higher, the resin particles become a film, and the abrasion resistance of the image is improved.
In the case of heating and pressurizing, the pressure at the time of pressurization is preferably 0.1 MPa to 3.0 MPa, more preferably 0.1 MPa to 1.0 MPa, and further preferably 0.1 MPa to 0.5 MPa in terms of surface smoothing. .
　加熱の方法としては、特に制限されず、例えば、ニクロム線ヒーター等の発熱体で加熱する方法、温風又は熱風を供給する方法、ハロゲンランプ、赤外線ランプ等で加熱する方法など、非接触で乾燥させる方法が好適である。
　加熱加圧の方法としては、特に制限されず、例えば、熱板を被記録材料の画像形成面に押圧する方法、一対の加熱加圧ローラ、一対の加熱加圧ベルト、又は被記録材料の画像形成面側に配された加熱加圧ベルトとその反対側に配された保持ローラとを備えた加熱加圧装置を用い、対をなすローラ等を通過させる方法など、接触させて加熱定着を行なう方法が好適である。 The heating method is not particularly limited, and for example, a method of heating with a heating element such as a nichrome wire heater, a method of supplying warm air or hot air, a method of heating with a halogen lamp, an infrared lamp, or the like, and drying without contact. The method of making it suitable is.
The method of heating and pressing is not particularly limited. For example, a method of pressing a hot plate against the image forming surface of the recording material, a pair of heating and pressing rollers, a pair of heating and pressing belts, or an image of the recording material. Using a heating and pressing apparatus having a heating and pressing belt arranged on the forming surface side and a holding roller arranged on the opposite side, heat fixing is performed by contacting them, such as a method of passing a pair of rollers. The method is preferred.
　加熱加圧する場合、好ましいニップ時間は、１ミリ秒～１０秒であり、より好ましくは２ミリ秒～１秒であり、更に好ましくは４ミリ秒～１００ミリ秒である。また、好ましいニップ幅は、０．１ｍｍ～１００ｍｍであり、より好ましくは０．５ｍｍ～５０ｍｍであり、更に好ましくは１ｍｍ～１０ｍｍである。 In the case of heating and pressing, a preferable nip time is 1 to 10 seconds, more preferably 2 to 1 second, and further preferably 4 to 100 milliseconds. The preferable nip width is 0.1 mm to 100 mm, more preferably 0.5 mm to 50 mm, and still more preferably 1 mm to 10 mm.
　加熱加圧ローラとしては、金属製の金属ローラでもよいし、金属製の芯金の周囲に弾性体からなる被覆層と、必要に応じて表面層（「離型層」ともいう。）と、が設けられたものでもよい。後者の芯金は、例えば、鉄製、アルミニウム製、ステンレス（ＳＵＳ）製等の円筒体で構成することができ、芯金の表面は、被覆層で少なくとも一部が覆われているものが好ましい。被覆層は、特に、離型性を有するシリコーン樹脂又はフッ素樹脂で形成されていることが好ましい。また、加熱加圧ローラの一方の芯金内部には、発熱体が内蔵されていることが好ましく、ローラ間に被記録材料を通すことによって、加熱処理と加圧処理とを同時に施したり、又は必要に応じて、２つの加熱ローラを用いて被記録材料を挟んで加熱したりしてもよい。発熱体としては、ハロゲンランプヒーター、セラミックヒーター、ニクロム線等が好ましい。 The heat and pressure roller may be a metal metal roller, a coating layer made of an elastic body around a metal core, and a surface layer (also referred to as a “release layer”) as necessary. May be provided. The latter core metal can be formed of a cylindrical body made of, for example, iron, aluminum, or stainless steel (SUS), and the surface of the core metal is preferably at least partially covered with a coating layer. The covering layer is particularly preferably formed of a silicone resin or fluororesin having releasability. Further, it is preferable that a heating element is built in one core metal of the heat and pressure roller, and the heat treatment and the pressure treatment are performed simultaneously by passing a recording material between the rollers, or If necessary, the recording material may be sandwiched and heated using two heating rollers. As the heating element, a halogen lamp heater, a ceramic heater, a nichrome wire or the like is preferable.
　加熱加圧装置に用いられる加熱加圧ベルトを構成するベルト基材としては、シームレスのニッケル電鍮が好ましく、基材の厚さは１０μｍ～１００μｍが好ましい。また、ベルト基材の材質としては、ニッケル以外にもアルミニウム、鉄、ポリエチレン等を用いることができる。シリコーン樹脂又はフッ素樹脂を設ける場合は、これら樹脂を用いて形成される層の厚みは、１μｍ～５０μｍが好ましく、１０μｍ～３０μｍがより好ましい。 As the belt base material constituting the heat and pressure belt used in the heat and pressure apparatus, seamless nickel brass is preferable, and the thickness of the base material is preferably 10 μm to 100 μm. Further, as the material of the belt base material, aluminum, iron, polyethylene or the like can be used in addition to nickel. When a silicone resin or a fluororesin is provided, the thickness of the layer formed using these resins is preferably 1 μm to 50 μm, and more preferably 10 μm to 30 μm.
　圧力（即ち、ニップ圧）を実現するには、例えば、加熱加圧ローラ等のローラ両端に、ニップ間隙を考慮して所望のニップ圧が得られるように、張力を有するバネ等の弾性部材を選択して設置すればよい。 In order to achieve the pressure (that is, the nip pressure), for example, elastic members such as springs having tension are provided at both ends of the roller such as a heat pressure roller so that a desired nip pressure can be obtained in consideration of the nip gap. Select and install.
　加熱加圧ローラ又は加熱加圧ベルトを用いる場合の被記録材料の搬送速度は、２００ｍｍ／秒～７００ｍｍ／秒が好ましく、３００ｍｍ／秒～６５０ｍｍ／秒がより好ましく、４００ｍｍ／秒～６００ｍｍ／秒が更に好ましい。 When the heating and pressing roller or the heating and pressing belt is used, the recording material conveyance speed is preferably 200 mm / second to 700 mm / second, more preferably 300 mm / second to 650 mm / second, and 400 mm / second to 600 mm / second. Further preferred.
－オーバーコート工程－
　オーバーコート工程では、被記録材料の、画像形成工程（及び場合により加熱定着工程）で画像が形成された側の少なくとも一部に、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子、及び水を含むオーバーコート液を付与する。 -Overcoat process-
In the overcoat process, the recording material has a group represented by the formula (1) on at least a part on the side where the image is formed in the image forming process (and in some cases, the heat fixing process), and carboxy. An overcoat liquid containing resin particles having no group and water is applied.
　オーバーコート液の付与は、塗布法、インクジェット法、浸漬法等の公知の方法により行うことができる。塗布法としては、既述の前処理工程における公知の塗布法と同様のものが挙げられる。 The overcoat liquid can be applied by a known method such as a coating method, an ink jet method, or an immersion method. Examples of the coating method include the same as the known coating methods in the above-described pretreatment step.
　オーバーコート工程は、インク組成物を用いた画像形成工程後に設けられる。すなわち、被記録材料上にインク組成物を付与して所望の画像が形成された後、被記録材料の画像を含む画像形成面の少なくとも一部（被記録材料の画像が形成された側の少なくとも一部）にオーバーコート液を付与する。この場合、オーバーコートは、画像形成面における、画像が形成された画像部のみ、画像が非形成の非画像部のみ、又は画像形成面の全体のいずれに施してもよく、効果の観点からは、画像形成面の全体にオーバーコートが施される場合が好ましい。
　これにより、被記録材料の画像形成面における光沢性が効果的に改善される。 The overcoat process is provided after the image forming process using the ink composition. That is, after a desired image is formed by applying the ink composition on the recording material, at least a part of the image forming surface including the image of the recording material (at least on the side where the image of the recording material is formed) Apply an overcoat solution to a part). In this case, the overcoat may be applied only on the image forming surface, only on the image portion where the image is formed, only on the non-image portion where the image is not formed, or on the entire image forming surface. It is preferable that an overcoat is applied to the entire image forming surface.
Thereby, the glossiness on the image forming surface of the recording material is effectively improved.
　オーバーコート液の付与量（好ましくは、塗布量）は、光沢性の観点から、２．０ｇ／ｍ２～６．０ｇ／ｍ２が好ましく、３．０ｇ／ｍ２～５．０ｇ／ｍ２がより好ましい。 Application amount of the overcoat solution (preferably, the coating weight), from the viewpoint of glossiness, 2.0g / m 2 ~ 6.0g / m 2 are preferred, 3.0g / m 2 ~ 5.0g / m 2 Is more preferable.
　以下、本発明を実施例により更に具体的に説明するが、本発明はその主旨を超えない限り、以下の実施例に限定されるものではない。 Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.
　なお、実施例において、樹脂（水不溶性樹脂を含む）の粒子の体積平均粒子径は、以下の方法により測定した。すなわち、樹脂の粒子の体積平均粒子径は、樹脂の粒子の水分散液の固形分濃度が２質量％になるように濃度調整した水分散液を用意し、液温を２５℃に調整した後、ナノトラック粒度分布測定装置（製品名：ＵＰＡ－ＥＸ１５０、日機装（株））を用いて、動的光散乱法により測定した。 In Examples, the volume average particle diameter of resin (including water-insoluble resin) particles was measured by the following method. That is, after preparing a water dispersion whose volume average particle diameter of the resin particles is adjusted so that the solid content concentration of the water dispersion of the resin particles is 2% by mass, and adjusting the liquid temperature to 25 ° C. Measurement was performed by a dynamic light scattering method using a nanotrack particle size distribution measuring apparatus (product name: UPA-EX150, Nikkiso Co., Ltd.).
＜樹脂の粒子の作製＞
－樹脂の粒子Ａ－１の作製－
　撹拌機及び冷却管を備えた５００ｍｌの三口フラスコに、界面活性剤（乳化剤）であるドデシルベンゼンスルホン酸ナトリウムの６２質量％水溶液（東京化成工業（株））２．６ｇと水１９０ｇとを加えて、窒素雰囲気下、８０℃で加熱し、更に、水１０ｇに重合開始剤であるペルオキソ二硫酸カリウム（和光純薬工業（株））０．４ｇを加えて溶解させた溶液Ａと、原料モノマーとして、メトキシポリエチレングリコール（５００）モノメタクリレート（製品名、製品コード：ＣＤ５５２、サートマー・ジャパン（株））２８．０ｇ、２－エチルヘキシルアクリレート（和光純薬工業（株））１５．０ｇ、及びスチレン（和光純薬工業（株））５７．０ｇを混合した溶液Ｂと、を３時間かけて同時に滴下した。滴下終了後、更に３時間反応させた後、水を加えて樹脂の粒子の固形分濃度を３０質量％に調整し、樹脂の粒子Ａ－１の水分散液を得た。
　得られた水分散液中の樹脂の粒子Ａ－１の体積平均粒子径を、既述の方法により測定したところ、３５ｎｍであった。また、粒子Ａ－１に含まれる樹脂の重量平均分子量（Ｍｗ）を、既述の方法により測定したところ、５０，０００であった。さらに、粒子Ａ－１に含まれる樹脂中の、式（１）で表される基の合計含有量を算出したところ、樹脂１ｇ当たり０．２４ｇであった。 <Preparation of resin particles>
-Preparation of resin particles A-1-
To a 500 ml three-necked flask equipped with a stirrer and a condenser tube, 2.6 g of a 62% by mass aqueous solution of sodium dodecylbenzenesulfonate (Tokyo Kasei Kogyo Co., Ltd.) as a surfactant (emulsifier) and 190 g of water were added. The solution A was heated at 80 ° C. in a nitrogen atmosphere, and further dissolved by adding 0.4 g of potassium peroxodisulfate (Wako Pure Chemical Industries, Ltd.) as a polymerization initiator to 10 g of water, and as a raw material monomer Methoxypolyethylene glycol (500) monomethacrylate (product name, product code: CD552, Sartomer Japan, Inc.) 28.0 g, 2-ethylhexyl acrylate (Wako Pure Chemical Industries, Ltd.) 15.0 g, and styrene (wa Solution B mixed with 57.0 g of Kojun Pharmaceutical Co., Ltd. was added dropwise simultaneously over 3 hours. After completion of the dropwise addition, the mixture was further reacted for 3 hours, and then water was added to adjust the solid content concentration of the resin particles to 30% by mass to obtain an aqueous dispersion of resin particles A-1.
The volume average particle size of the resin particles A-1 in the obtained aqueous dispersion was 35 nm as measured by the method described above. Further, the weight average molecular weight (Mw) of the resin contained in the particles A-1 was 50,000 as measured by the method described above. Further, the total content of the group represented by the formula (1) in the resin contained in the particles A-1 was calculated and found to be 0.24 g per 1 g of resin.
－樹脂の粒子Ａ－２～Ａ－１５の作製－
　樹脂の粒子Ａ－１の作製に用いた原料モノマーを、下記の表１に示すように変更したこと以外は、樹脂の粒子Ａ－１の作製と同様の操作を行い、樹脂の粒子Ａ－２～Ａ－１５の水分散液を得た。
　得られた水分散液中の樹脂の粒子Ａ－２～Ａ－１５の体積平均粒子径、及び、粒子Ａ－２～Ａ－１５に含まれる樹脂の重量平均分子量（Ｍｗ）を、既述の方法により測定した。また、粒子Ａ－２～Ａ－１５に含まれる樹脂中の、式（１）で表される基の合計含有量を算出した。
　結果を表１に示す。 -Preparation of resin particles A-2 to A-15-
Resin particles A-2 were prepared in the same manner as in the production of resin particles A-1, except that the raw material monomers used in the production of resin particles A-1 were changed as shown in Table 1 below. An aqueous dispersion of ~ A-15 was obtained.
The volume average particle diameter of the resin particles A-2 to A-15 and the weight average molecular weight (Mw) of the resin contained in the particles A-2 to A-15 in the obtained aqueous dispersion are described above. Measured by the method. Further, the total content of the group represented by the formula (1) in the resins contained in the particles A-2 to A-15 was calculated.
The results are shown in Table 1.
－樹脂の粒子Ａ－１６の作製－
　撹拌機、温度計、還流冷却管、及び窒素ガス導入管を備えた２リットル三口フラスコ（反応容器）に、メチルエチルケトン３５０．０ｇを入れ、窒素雰囲気下、７５℃まで昇温した。反応容器内の温度を７５℃に保ちながら（以下、反応終了まで還流）、２－エチルヘキシルアクリレート（和光純薬工業（株））７３．５ｇ、スチレン（和光純薬工業（株））２７６．５ｇ、メチルエチルケトン５０．０ｇ、及び「Ｖ－６０１」（重合開始剤、和光純薬工業（株））１．４ｇを混合した混合溶液を、２時間で滴下が完了するように等速で滴下した。滴下終了後の溶液に、「Ｖ－６０１」０．６ｇ及びメチルエチルケトン２５．０ｇを混合した混合溶液を加え、７５℃で２時間撹拌した後、更に「Ｖ－６０１」０．５ｇ及びイソプロパノール２５．０ｇを混合した混合溶液を加え、７５℃で２時間撹拌した。その後、反応容器内の温度を８５℃に昇温して、更に２時間撹拌を続け、２－エチルヘキシルアクリレート／スチレン（＝２１／７９［質量比］）共重合体のポリマー溶液を得た。
　得られたポリマー溶液中の共重合体の重量平均分子量（Ｍｗ）を、粒子Ａ－１に含まれる樹脂の重量平均分子量（Ｍｗ）と同様の方法により測定したところ、５７，０００であった。
　次に、得られたポリマー溶液５００ｇを秤量し、このポリマー溶液にイソプロパノール３００ｇを加え、反応容器内温度を８０℃に昇温した。次いで、式（１）で表される基を有するノニオン性界面活性剤（製品名：エマルゲン　１０９Ｐ、ポリオキシエチレンラウリルエーテル、花王（株））４０ｇを純水８００ｇに溶解した水溶液を２０ｍｌ／ｍｉｎの速度で滴下し、乳化した後、大気圧下にて反応容器内温度８０℃で２時間、８５℃で２時間、及び９０℃で２時間保った。次いで、反応容器内を減圧にし、イソプロパノール、メチルエチルケトン、及び純水を合計で９７５ｇ留去した。最後に、固形分濃度（ポリマー粒子濃度）が３０．０質量％となるように純水を加えて、樹脂の粒子Ａ－１６の水分散液を得た。
　得られた水分散液中の樹脂の粒子Ａ－１６の体積平均粒子径を、既述の方法により測定したところ、８６ｎｍであった。さらに、粒子Ａ－１６に含まれる樹脂中の、式（１）で表される基の合計含有量を算出したところ、樹脂１ｇ当たり０．１１ｇであった。 -Production of resin particles A-16-
In a 2-liter three-necked flask (reaction vessel) equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, 350.0 g of methyl ethyl ketone was placed and heated to 75 ° C. in a nitrogen atmosphere. While maintaining the temperature in the reaction vessel at 75 ° C. (hereinafter refluxed until the end of the reaction), 73.5 g of 2-ethylhexyl acrylate (Wako Pure Chemical Industries, Ltd.), 276.5 g of styrene (Wako Pure Chemical Industries, Ltd.) Then, a mixed solution in which 50.0 g of methyl ethyl ketone and 1.4 g of “V-601” (polymerization initiator, Wako Pure Chemical Industries, Ltd.) were mixed was added dropwise at a constant speed so that the addition was completed in 2 hours. A mixed solution obtained by mixing 0.6 g of “V-601” and 25.0 g of methyl ethyl ketone was added to the solution after completion of the dropwise addition. After stirring at 75 ° C. for 2 hours, 0.5 g of “V-601” and 25. A mixed solution mixed with 0 g was added and stirred at 75 ° C. for 2 hours. Thereafter, the temperature in the reaction vessel was raised to 85 ° C., and stirring was further continued for 2 hours to obtain a polymer solution of 2-ethylhexyl acrylate / styrene (= 21/79 [mass ratio]) copolymer.
The weight average molecular weight (Mw) of the copolymer in the obtained polymer solution was measured by the same method as the weight average molecular weight (Mw) of the resin contained in the particles A-1, and found to be 57,000.
Next, 500 g of the obtained polymer solution was weighed, 300 g of isopropanol was added to this polymer solution, and the temperature in the reaction vessel was raised to 80 ° C. Then, a nonionic surfactant having a group represented by the formula (1) (product name: Emulgen 109P, polyoxyethylene lauryl ether, Kao Corporation) in an aqueous solution of 20 ml / min dissolved in 800 g of pure water. After dropping at a speed and emulsifying, the temperature in the reaction vessel was kept at 80 ° C. for 2 hours, 85 ° C. for 2 hours, and 90 ° C. for 2 hours under atmospheric pressure. Next, the pressure in the reaction vessel was reduced, and 975 g of isopropanol, methyl ethyl ketone, and pure water were distilled off in total. Finally, pure water was added so that the solid content concentration (polymer particle concentration) was 30.0% by mass to obtain an aqueous dispersion of resin particles A-16.
The volume average particle size of the resin particles A-16 in the obtained aqueous dispersion was 86 nm as measured by the method described above. Further, when the total content of the group represented by the formula (1) in the resin contained in the particles A-16 was calculated, it was 0.11 g per 1 g of resin.
－樹脂の粒子Ｒ－１～Ｒ－３の作製－
　樹脂の粒子Ａ－１の作製に用いた原料モノマーを、下記の表１に示すように変更したこと以外は、樹脂の粒子Ａ－１の作製と同様の操作を行い、樹脂の粒子Ｒ－１～Ｒ－３の水分散液を得た。
　得られた水分散液中の樹脂の粒子Ｒ－１～Ｒ－３の体積平均粒子径、及び、粒子Ｒ－１～Ｒ－３に含まれる樹脂の重量平均分子量（Ｍｗ）を、既述の方法により測定した。また、粒子Ｒ－１～Ｒ－３に含まれる樹脂中の、式（１）で表される基の合計含有量を算出した。
　結果を表１に示す。 -Preparation of resin particles R-1 to R-3-
Resin particles R-1 were prepared in the same manner as in the production of resin particles A-1, except that the raw material monomers used in the production of resin particles A-1 were changed as shown in Table 1 below. An aqueous dispersion of ~ R-3 was obtained.
The volume average particle diameter of the resin particles R-1 to R-3 and the weight average molecular weight (Mw) of the resin contained in the particles R-1 to R-3 in the obtained aqueous dispersion are described above. Measured by the method. Further, the total content of the group represented by the formula (1) in the resins contained in the particles R-1 to R-3 was calculated.
The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000007
 
Figure JPOXMLDOC01-appb-T000007
 
　表１中、本開示における樹脂の粒子（即ち、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子）を「樹脂の粒子」と表記し、本開示における樹脂の粒子に該当しないものを「比較樹脂の粒子」と表記した。
　表１の原料モノマーの組成の欄に記載の数値は、その原料モノマーの使用量（単位：質量部）を示し、「－」は、その原料モノマーを使用していないことを意味する。 In Table 1, resin particles in the present disclosure (that is, resin particles having a group represented by the formula (1) and not having a carboxy group) are referred to as “resin particles”, and the present disclosure Those not corresponding to the resin particles in are referred to as “comparative resin particles”.
The numerical values described in the column of the raw material monomer in Table 1 indicate the amount of the raw material monomer used (unit: part by mass), and “-” means that the raw material monomer is not used.
　表１に記載の原料モノマーの詳細は、以下の通りである。
　・（２）－１～（２）－１０：下記の表２に示すとおり。
　・アクリル酸２－エチルへキシル：式（３）で表される構成単位を形成するための原料モノマー
　・メタクリル酸メチル：：式（３）で表される構成単位を形成するための原料モノマー
　・スチレン：式（４）で表される構成単位を形成するための原料モノマー
　・メタクリル酸：カルボキシ基を有する原料モノマー Details of the raw material monomers listed in Table 1 are as follows.
(2) -1 to (2) -10: As shown in Table 2 below.
2-ethylhexyl acrylate: raw material monomer for forming the structural unit represented by formula (3) methyl methacrylate :: raw material monomer for forming the structural unit represented by formula (3) Styrene: Raw material monomer for forming the structural unit represented by formula (4) Methacrylic acid: Raw material monomer having carboxy group
Figure JPOXMLDOC01-appb-T000008
 
Figure JPOXMLDOC01-appb-T000008
 
＜オーバーコート液の調製＞
－オーバーコート液１の調製－
　下記の組成に示す各成分を混合し、オーバーコート液１を調製した。
　得られたオーバーコート液１のｐＨを既述の方法により測定したところ、７．８であった。また、オーバーコート液１の表面張力を既述の方法により測定したところ、２７．８ｍＮ／ｍであった。 <Preparation of overcoat solution>
-Preparation of overcoat solution 1-
Each component shown to the following composition was mixed and the overcoat liquid 1 was prepared.
It was 7.8 when pH of the obtained overcoat liquid 1 was measured by the above-mentioned method. Moreover, it was 27.8 mN / m when the surface tension of the overcoat liquid 1 was measured by the above-mentioned method.
（組成）
　・上記にて得られた樹脂の粒子Ａ－１の水分散液　　　　７５質量％
　・ワックス分散物　　　　　　　　　　　　　　　　　　１５質量％
　（ＡＱＵＡＣＥＲ（登録商標）５３１、ＢＹＫ－Ｃｈｅｍｉｅ社）
　・イソプロピルアルコール（ＩＰＡ）　　　　　　　　　　３質量％
　・ブチルカルビトール　　　　　　　　　　　　　　　　　１質量％
　・スルホコハク酸－ジ－２－エチルヘキシルナトリウム　　１質量％
　・イオン交換水　　　　　　　　　　　合計で１００質量％となる量 (composition)
-75% by weight of aqueous dispersion of resin particles A-1 obtained above
・ Wax dispersion 15% by mass
(AQUACER (registered trademark) 531, BYK-Chemie)
・ Isopropyl alcohol (IPA) 3% by mass
・ Butyl carbitol 1% by mass
・ Sulfosuccinic acid-di-2-ethylhexyl sodium 1% by mass
・ Ion-exchanged water Total amount of 100% by mass
－オーバーコート液２～１９の調製－
　オーバーコート液１の調製において、樹脂の粒子Ａ－１の水分散液を、樹脂の粒子Ａ－２～Ａ－１６及びＲ－１～Ｒ－３の水分散液のいずれかに変更したこと以外は、オーバーコート液１の調製と同様の操作を行い、オーバーコート液２～１９を調製した。
　得られたオーバーコート液２～１９のｐＨを既述の方法により測定したところ、いずれも６．４～８．７の範囲内であった。また、オーバーコート液２～１９の表面張力を既述の方法により測定したところ、いずれも２５．３ｍＮ／ｍ～３３．６ｍＮ／ｍの範囲内であった。 -Preparation of overcoat solutions 2-19-
Other than changing the aqueous dispersion of resin particles A-1 to any of aqueous dispersions of resin particles A-2 to A-16 and R-1 to R-3 in the preparation of overcoat liquid 1 Were the same as the preparation of the overcoat solution 1, and overcoat solutions 2 to 19 were prepared.
The pH values of the obtained overcoat solutions 2 to 19 were measured by the method described above, and all were within the range of 6.4 to 8.7. Further, the surface tensions of the overcoat liquids 2 to 19 were measured by the method described above, and all were within the range of 25.3 mN / m to 33.6 mN / m.
＜前処理液の調製＞
－前処理液１の調製－
　下記の組成に示す各成分を混合し、前処理液１を調製した。
　得られた前処理液のｐＨを既述の方法により測定したところ、０．８であった。また、前処理液の表面張力を既述の方法により測定したところ、３２．８ｍＮ／ｍであった。 <Preparation of pretreatment liquid>
-Preparation of pretreatment solution 1-
Each component shown to the following composition was mixed and the pretreatment liquid 1 was prepared.
It was 0.8 when the pH of the obtained pretreatment liquid was measured by the above-mentioned method. Moreover, it was 32.8 mN / m when the surface tension of the pretreatment liquid was measured by the method described above.
（組成）
　・ジエチレングリコールモノエチルエーテル　　　　　　　４質量％
　・トリプロピレングリコールモノメチルエーテル　　　　　４質量％
　・マロン酸（有機酸）　　　　　　　　　　　　　　１７．３質量％
　・プロパントリカルボン酸（有機酸）　　　　　　　　４．３質量％
　・リン酸（無機酸）　　　　　　　　　　　　　　　　４．３質量％
　・下記の水不溶性樹脂の粒子Ｃ－１　　　　　　　　　　　５質量％
　・ベンゾトリアゾール　　　　　　　　　　　　　　　　　１質量％
　・消泡剤　　　　シリコーンオイルの質量が０．０１質量％となる量
　（製品名：ＴＳＡ－７３９、固形分量：１５質量％、エマルション型シリコーン消泡剤、モメンティブ・パフォーマンス・マテリアルズ・ジャパン合同会社）
　・イオン交換水　　　　　　　　　　　合計で１００質量％となる量 (composition)
・ Diethylene glycol monoethyl ether 4% by mass
・ Tripropylene glycol monomethyl ether 4% by mass
-Malonic acid (organic acid) 17.3% by mass
Propane tricarboxylic acid (organic acid) 4.3% by mass
・ Phosphoric acid (inorganic acid) 4.3% by mass
-5% by mass of the following water-insoluble resin particles C-1
・ Benzotriazole 1% by mass
・ Antifoaming agent The amount of silicone oil to be 0.01% by mass (Product name: TSA-739, solid content: 15% by mass, emulsion type silicone antifoaming agent, Momentive Performance Materials Japan GK)
・ Ion-exchanged water Total amount of 100% by mass
－水不溶性樹脂の粒子Ｃ－１の作製－
　撹拌機及び冷却管を備えた１，０００ｍｌの三口フラスコに、界面活性剤（乳化剤）であるドデシルベンゼンスルホン酸ナトリウムの６２質量％水溶液（東京化成工業（株））１．５ｇ及び水３５０ｇを加えて、窒素雰囲気下、８０℃で加熱し、更に、水２０ｇに、重合開始剤であるペルオキソ二硫酸カリウム（和光純薬工業（株））０．８５ｇ、及び原料モノマーとしてアクリルアミド－２－プロパンスルホン酸ナトリウムの５０質量％水溶液（Ａｌｄｒｉｃｈ社）１２．４ｇを加えて溶解させた溶液Ａと、原料モノマーとして、スチレン（和光純薬工業（株））１４．９ｇ、メチルメタクリレート（和光純薬工業（株））１２．２ｇ、及びメタクリル酸（和光純薬工業（株））１５．４ｇを混合した溶液Ｂと、を３時間かけて同時に滴下した。滴下終了後、更に３時間反応させて、水不溶性樹脂の粒子Ｃ－１の水分散液（水不溶性樹脂の粒子Ｃ－１の固形分量：１１．４質量％）４２７ｇを得た。
　得られた水分散液中の水不溶性樹脂の粒子Ｃ－１の体積平均粒子径を、既述の方法により測定したところ、３２ｎｍであった。また、粒子Ｃ－１に含まれる水不溶性樹脂の重量平均分子量（Ｍｗ）を、既述の方法により測定したところ、１３５，０００であった。 -Preparation of water-insoluble resin particles C-1-
To a 1,000 ml three-necked flask equipped with a stirrer and a condenser tube was added 1.5 g of a 62% by weight aqueous solution of sodium dodecylbenzenesulfonate (Tokyo Chemical Industry Co., Ltd.) and 350 g of water as a surfactant (emulsifier). The mixture was heated at 80 ° C. in a nitrogen atmosphere, and further, 20 g of water, 0.85 g of potassium peroxodisulfate (Wako Pure Chemical Industries, Ltd.) as a polymerization initiator, and acrylamide-2-propanesulfone as a raw material monomer Solution A in which 12.4 g of a 50% by weight aqueous solution of sodium acid (Aldrich) was added and dissolved, and 14.9 g of styrene (Wako Pure Chemical Industries) as a raw material monomer, methyl methacrylate (Wako Pure Chemical Industries ( Co., Ltd.) 12.2 g and methacrylic acid (Wako Pure Chemical Industries, Ltd.) 15.4 g mixed solution B were simultaneously added dropwise over 3 hours. It was. After completion of the dropwise addition, the reaction was further continued for 3 hours to obtain 427 g of an aqueous dispersion of water-insoluble resin particles C-1 (solid content of water-insoluble resin particles C-1: 11.4% by mass).
The volume average particle size of the water-insoluble resin particles C-1 in the obtained aqueous dispersion was measured by the method described above, and was 32 nm. Further, the weight average molecular weight (Mw) of the water-insoluble resin contained in the particles C-1 was measured by the above-described method and found to be 135,000.
＜インク組成物の調製＞
（ポリマー分散剤Ｐ－１の合成）
　下記スキームに従って、以下に示す方法によりポリマー分散剤Ｐ－１を合成した。 <Preparation of ink composition>
(Synthesis of polymer dispersant P-1)
According to the following scheme, a polymer dispersant P-1 was synthesized by the method shown below.
Figure JPOXMLDOC01-appb-C000009
 
Figure JPOXMLDOC01-appb-C000009
 
　撹拌機及び冷却管を備えた１リットルの三口フラスコに、メチルエチルケトン８８ｇを入れ、窒素雰囲気下、７２℃で加熱し、更に、メチルエチルケトン５０ｇに、ジメチル２，２’－アゾビスイソブチレート（重合開始剤）０．８５ｇ、ベンジルメタクリレート６０ｇ、メタクリル酸１０ｇ、及びメチルメタクリレート３０ｇを溶解させた溶液を、３時間かけて滴下した。滴下終了後、更に１時間反応させた後、メチルエチルケトン２ｇにジメチル２，２’－アゾビスイソブチレート（重合開始剤）０．４２ｇを溶解させた溶液を加え、７８℃に昇温して４時間加熱した。得られた反応溶液は、大過剰量のヘキサンに２回再沈殿させた後、析出した樹脂を乾燥することにより、ポリマー分散剤Ｐ－１を９６ｇ合成した。
　なお、ポリマー分散剤Ｐ－１における各構成単位の数字は「質量比」を表す。
　得られたポリマー分散剤Ｐ－１の組成は、プロトン核磁気共鳴分光法（１Ｈ－ＮＭＲ）にて確認した。また、ポリマー分散剤Ｐ－１の重量平均分子量（Ｍｗ）を既述の方法により測定したところ、４４，６００であった。さらに、ポリマー分散剤Ｐ－１の酸価をＪＩＳ規格（ＪＩＳ　Ｋ　００７０：１９９２）に準拠した方法により測定したところ、６５．２ｍｇＫＯＨ／ｇであった。 In a 1 liter three-necked flask equipped with a stirrer and a condenser, 88 g of methyl ethyl ketone was placed and heated at 72 ° C. in a nitrogen atmosphere. Further, 50 g of methyl ethyl ketone was charged with dimethyl 2,2′-azobisisobutyrate (polymerization initiation). Agent) A solution in which 0.85 g, benzyl methacrylate 60 g, methacrylic acid 10 g, and methyl methacrylate 30 g were dissolved was dropped over 3 hours. After completion of the dropwise addition, the mixture was further reacted for 1 hour, and then a solution in which 0.42 g of dimethyl 2,2′-azobisisobutyrate (polymerization initiator) was dissolved in 2 g of methyl ethyl ketone was added. Heated for hours. The obtained reaction solution was reprecipitated twice in a large excess amount of hexane, and the precipitated resin was dried to synthesize 96 g of polymer dispersant P-1.
The number of each structural unit in the polymer dispersant P-1 represents “mass ratio”.
The composition of the resulting polymer dispersant P-1 was confirmed by proton nuclear magnetic resonance spectroscopy ( 1 H-NMR). The weight average molecular weight (Mw) of the polymer dispersant P-1 was 44,600 as measured by the method described above. Furthermore, when the acid value of the polymer dispersant P-1 was measured by a method based on JIS standard (JIS K 0070: 1992), it was 65.2 mgKOH / g.
（顔料分散液の調製）
－シアン顔料分散液Ｃの調製－
　シアン顔料であるピグメント・ブルー１５：３（製品名：フタロシアニンブル－Ａ２２０、大日精化（株））１０質量部と、ポリマー分散剤Ｐ－１を５質量部と、メチルエチルケトン４２質量部と、１×１０３ｍｏｌ／ｌの水酸化ナトリウム水溶液（ＮａＯＨ水溶液；以下同じ。）５．５質量部と、イオン交換水８７．２質量部と、を混合し、ビーズミル（０．１ｍｍφのジルコニアビーズを使用）により２時間～６時間分散処理を行い、分散物を得た。次いで、得られた分散物を、減圧下、５５℃にてメチルエチルケトンを除去し、更に一部の水を除去した後、更に、高速遠心冷却機７５５０（（株）久保田製作所）を用いて、５０ｍｌ遠心管を使用し、回転数８，０００ｒｐｍ、で３０分間遠心処理を行った。遠心処理後、沈殿物以外の上澄み液を回収した。その後、吸光度スペクトルから顔料濃度を求め、顔料濃度が１０．２質量％の樹脂被覆顔料粒子（ポリマー分散剤で被覆された顔料）の分散物（シアン顔料分散液Ｃ）を得た。
　得られたシアン顔料分散液Ｃ中の樹脂被覆顔料粒子の平均粒子径は、１０５ｎｍであった。なお、平均粒子径は、既述の方法により測定した。 (Preparation of pigment dispersion)
-Preparation of cyan pigment dispersion C-
Pigment Blue 15: 3 which is a cyan pigment (product name: Phthalocyanine A220, Dainichi Seika Co., Ltd.), 5 parts by weight of polymer dispersant P-1, 42 parts by weight of methyl ethyl ketone, × 10 3 mol / l sodium hydroxide aqueous solution (NaOH aqueous solution; the same shall apply hereinafter) 5.5 parts by mass and ion-exchanged water 87.2 parts by mass are mixed with a bead mill (using 0.1 mmφ zirconia beads). ) For 2 to 6 hours to obtain a dispersion. Next, the methyl ethyl ketone was removed from the obtained dispersion at 55 ° C. under reduced pressure, and a part of the water was further removed. Then, using a high-speed centrifugal cooler 7550 (Kubota Co., Ltd.), 50 ml Centrifugation was performed for 30 minutes at a rotation speed of 8,000 rpm using a centrifuge tube. After centrifugation, the supernatant liquid other than the precipitate was collected. Thereafter, the pigment concentration was determined from the absorbance spectrum, and a dispersion (cyan pigment dispersion C) of resin-coated pigment particles (pigment coated with a polymer dispersant) having a pigment concentration of 10.2% by mass was obtained.
The average particle diameter of the resin-coated pigment particles in the obtained cyan pigment dispersion C was 105 nm. The average particle size was measured by the method described above.
－マゼンタ顔料分散液Ｍの調製－
　シアン顔料分散液Ｃの調製において、ピグメント・ブルー１５：３（製品名：フタロシアニンブル－Ａ２２０）の代わりに、マゼンタ顔料であるピグメント・レッド１２２（製品名：クロモファインマゼンタ６８８６、大日精化（株））を用いたこと以外は、シアン顔料分散液Ｃの調製と同様の操作を行い、樹脂被覆顔料粒子（ポリマー分散剤で被覆された顔料）の分散物（マゼンタ顔料分散液Ｍ）を得た。
　得られたマゼンタ顔料分散液Ｍ中の樹脂被覆顔料粒子の平均粒子径は、８５ｎｍであった。なお、平均粒子径は、既述の方法により測定した。 -Preparation of magenta pigment dispersion M-
In the preparation of Cyan Pigment Dispersion C, instead of Pigment Blue 15: 3 (Product Name: Phthalocyanine-A220), Pigment Red 122 (Product Name: Chromofine Magenta 6886, Dainippon Seika Co., Ltd.) )) Was used in the same manner as in the preparation of cyan pigment dispersion C to obtain a dispersion (magenta pigment dispersion M) of resin-coated pigment particles (pigment coated with a polymer dispersant). .
The average particle diameter of the resin-coated pigment particles in the obtained magenta pigment dispersion M was 85 nm. The average particle size was measured by the method described above.
－イエロー顔料分散液Ｙの調製－
　シアン顔料分散液Ｃの調製において、ピグメント・ブルー１５：３（製品名：フタロシアニンブル－Ａ２２０）の代わりに、イエロー顔料であるピグメントイエロー７４（製品名：セイカファストイエロー２０５４、大日精化（株））を用いたこと以外は、シアン顔料分散液Ｃの調製と同様の操作を行い、樹脂被覆顔料粒子（ポリマー分散剤で被覆された顔料）の分散物（イエロー顔料分散液Ｙ）を得た。
　得られたイエロー顔料分散液Ｙ中の樹脂被覆顔料粒子の平均粒子径は、８２ｎｍであった。なお、平均粒子径は、既述の方法により測定した。 -Preparation of yellow pigment dispersion Y-
In the preparation of cyan pigment dispersion C, instead of Pigment Blue 15: 3 (Product Name: Phthalocyanine-A220), Pigment Yellow 74 (Product Name: Seika Fast Yellow 2054, Dainichi Seika) ) Was used in the same manner as in the preparation of cyan pigment dispersion C to obtain a dispersion (yellow pigment dispersion Y) of resin-coated pigment particles (pigment coated with a polymer dispersant).
The average particle diameter of the resin-coated pigment particles in the obtained yellow pigment dispersion Y was 82 nm. The average particle size was measured by the method described above.
－ブラック顔料分散液Ｋの調製－
　シアン顔料分散液Ｃの調製において、ピグメント・ブルー１５：３（製品名：フタロシアニンブル－Ａ２２０）の代わりに、ブラック顔料であるカーボンブラック（製品名：ＮＩＰＥＸ１６０－ＩＱ、オリオンエンジニアドカーボンズ社）を用いたこと以外は、シアン顔料分散液Ｃの調製と同様の操作を行い、樹脂被覆顔料粒子（ポリマー分散剤で被覆された顔料）の分散物（ブラック顔料分散液Ｋ）を得た。
　得られたブラック顔料分散液Ｋ中の樹脂被覆顔料粒子の平均粒子径は、１３０ｎｍであった。なお、平均粒子径は、既述の方法により測定した。 -Preparation of black pigment dispersion K-
In preparation of Cyan Pigment Dispersion C, instead of Pigment Blue 15: 3 (Product name: Phthalocyanine A220), carbon black (Product Name: NIPEX160-IQ, Orion Engineered Carbons) is used. Except that it was used, the same operation as in the preparation of cyan pigment dispersion C was carried out to obtain a dispersion (black pigment dispersion K) of resin-coated pigment particles (pigment coated with a polymer dispersant).
The average particle diameter of the resin-coated pigment particles in the obtained black pigment dispersion K was 130 nm. The average particle size was measured by the method described above.
（樹脂粒子の調製）
－樹種粒子Ｂ－０１の調製－
　撹拌機、温度計、還流冷却管、及び窒素ガス導入管を備えた２リットルの三口フラスコ（反応容器）にメチルエチルケトン３６０．０ｇを仕込んで、７５℃まで昇温した。反応容器内の温度を７５℃に保ちながら、フェノキシエチルアクリレート１８０．０ｇ、メチルメタクリレート１６２．０ｇ、アクリル酸１８．０ｇ、メチルエチルケトン７２ｇ、及び「Ｖ－６０１」（重合開始剤、和光純薬工業（株））１．４４ｇを混合した混合溶液を、２時間で滴下が完了するように等速で滴下した。滴下終了後、「Ｖ－６０１」０．７２ｇ及びメチルエチルケトン３６．０ｇの混合溶液を加え、７５℃で２時間撹拌した後、更に「Ｖ－６０１」０．７２ｇ及びイソプロパノール３６．０ｇの混合溶液を加え、７５℃で２時間撹拌した後、８５℃に昇温して、更に２時間撹拌を続けた。このようにして、重合体溶液を得た。
　得られた重合体溶液に含まれる共重合体は、重量平均分子量（Ｍｗ）が６４，０００であり、酸価が３８．９ｍｇＫＯＨ／ｇであった。なお、酸価及び重量平均分子量は、既述
の方法により測定した。
　次に、重合体溶液６６８．３ｇを秤量し、イソプロパノール３８８．３ｇ、１ｍｏｌ／ｌのＮａＯＨ水溶液１４５．７ｍｌを加え、反応容器内の温度を８０℃に昇温した。次いで、反応容器内に蒸留水７２０．１ｇを２０ｍｌ／ｍｉｎの速度で滴下し、水分散化した。その後、大気圧下にて反応容器内の温度を、８０℃で２時間、８５℃で２時間、９０℃で２時間保った後、反応容器内を減圧してイソプロパノール、メチルエチルケトン、及び蒸留水を合計で９１３．７ｇ留去した。このようにして、固形分濃度２８．０質量％の樹脂粒子（Ｂ－０１）の水分散物（エマルション）を得た。
　樹脂粒子（Ｂ－０１）の樹脂における各構成単位を以下に示す。下記の式中の各構成単位の数字は「質量比」を表す。 (Preparation of resin particles)
-Preparation of tree seed particles B-01-
360.0 g of methyl ethyl ketone was charged into a 2 liter three-necked flask (reaction vessel) equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, and the temperature was raised to 75 ° C. While maintaining the temperature in the reaction vessel at 75 ° C., 180.0 g of phenoxyethyl acrylate, 162.0 g of methyl methacrylate, 18.0 g of acrylic acid, 72 g of methyl ethyl ketone, and “V-601” (polymerization initiator, Wako Pure Chemical Industries ( Ltd.)) was mixed dropwise at a constant speed so that the dripping was completed in 2 hours. After completion of dropping, a mixed solution of 0.72 g of “V-601” and 36.0 g of methyl ethyl ketone was added and stirred at 75 ° C. for 2 hours, and then a mixed solution of 0.72 g of “V-601” and 36.0 g of isopropanol was added. In addition, after stirring at 75 ° C. for 2 hours, the temperature was raised to 85 ° C., and stirring was further continued for 2 hours. In this way, a polymer solution was obtained.
The copolymer contained in the obtained polymer solution had a weight average molecular weight (Mw) of 64,000 and an acid value of 38.9 mgKOH / g. The acid value and the weight average molecular weight were measured by the methods described above.
Next, 668.3 g of the polymer solution was weighed, 388.3 g of isopropanol and 145.7 ml of 1 mol / l NaOH aqueous solution were added, and the temperature in the reaction vessel was raised to 80 ° C. Next, 720.1 g of distilled water was dropped into the reaction vessel at a rate of 20 ml / min to disperse in water. Thereafter, the temperature in the reaction vessel is maintained at 80 ° C. for 2 hours, 85 ° C. for 2 hours, and 90 ° C. for 2 hours, and then the reaction vessel is depressurized to give isopropanol, methyl ethyl ketone, and distilled water. A total of 913.7 g was distilled off. Thus, an aqueous dispersion (emulsion) of resin particles (B-01) having a solid content concentration of 28.0% by mass was obtained.
Each structural unit in the resin of the resin particle (B-01) is shown below. The number of each structural unit in the following formula represents “mass ratio”.
Figure JPOXMLDOC01-appb-C000010
 
Figure JPOXMLDOC01-appb-C000010
 
（インク１の作製）
　上記にて得られた各顔料分散液（マゼンタ顔料分散液Ｍ、ブラック顔料分散液Ｋ、シアン顔料分散液Ｃ、及びイエロー顔料分散液Ｙ）、並びに樹脂粒子（Ｂ－０１）を用い、下記の表３に示す組成となるように各成分を混合し、各インク組成物（マゼンタインク組成物Ｍ１、ブラックインク組成物Ｋ１、シアンインク組成物Ｃ１、イエローインク組成物Ｙ１）をそれぞれ調製した。
　調製した各インク組成物を、プラスチック製のディスポーサブルシリンジに接続した、ポリフッ化ビニリデン（ＰＶＤＦ）５μｍフィルター（Ｍｉｌｌｅｘ　ＳＶ、直径：２５ｍｍ、ミリポア社）で濾過し、４色のインク（マゼンタインクＭ１、ブラックインクＫ１、シアンインクＣ１、及びイエローインクＹ１）からなるインク１を得た。
　得られたインク１のｐＨを既述の方法により測定したところ、８．２であった。また、インク１の粘度を既述の方法により測定したところ、３７．６ｍＰａ・ｓであった。 (Preparation of ink 1)
Using each pigment dispersion (magenta pigment dispersion M, black pigment dispersion K, cyan pigment dispersion C, and yellow pigment dispersion Y) obtained above and resin particles (B-01), the following: Each component was mixed so as to have the composition shown in Table 3 to prepare each ink composition (magenta ink composition M1, black ink composition K1, cyan ink composition C1, yellow ink composition Y1).
Each prepared ink composition was filtered through a polyvinylidene fluoride (PVDF) 5 μm filter (Millex SV, diameter: 25 mm, Millipore) connected to a plastic disposable syringe, and four inks (magenta ink M1, black) Ink 1 composed of ink K1, cyan ink C1, and yellow ink Y1) was obtained.
The pH of the obtained ink 1 was measured by the above-described method and found to be 8.2. Further, the viscosity of the ink 1 was measured by the above-described method and found to be 37.6 mPa · s.
Figure JPOXMLDOC01-appb-T000011
 
Figure JPOXMLDOC01-appb-T000011
 
　表３に記載の成分の詳細は、以下の通りである。
　・サンニックスＧＰ－２５０：三洋化成工業（株）の有機溶剤
　・オルフィン（登録商標）Ｅ１０１０：日信化学工業（株）のノニオン性界面活性剤 Details of the components described in Table 3 are as follows.
・ Sanix GP-250: Organic solvent of Sanyo Chemical Industries ・ Orphine (registered trademark) E1010: Nonionic surfactant of Nissin Chemical Industry Co., Ltd.
＜実施例１～１６及び比較例１～３＞
　上記のように調製した、インク１、前処理液１、及びオーバーコート液１～１９を用い、下記の表４に示すインクセット１～１９を作製した。
　作製したインクセット１～１９を用い、以下の手順で画像を形成し、評価した。 <Examples 1 to 16 and Comparative Examples 1 to 3>
Using ink 1, pretreatment liquid 1, and overcoat liquids 1 to 19 prepared as described above, ink sets 1 to 19 shown in Table 4 below were produced.
Images were formed and evaluated by the following procedures using the ink sets 1 to 19 prepared.
－画像形成－
　被記録材料である基材として、コート紙（製品名：ボンアイボリー＋、米坪：３１０ｇ／ｍ２、王子製紙（株）；塗工紙）を用い、下記の方法により画像を形成した。
　なお、画像の形成に際しては、前処理工程の後、１０秒以内に、画像形成工程においてインクの打滴が開始されるようにした。 -Image formation-
An image was formed by the following method using coated paper (product name: Bon Ivory +, US tsubo: 310 g / m 2 , Oji Paper Co., Ltd .; coated paper) as a recording material.
In forming an image, ink ejection was started in the image forming process within 10 seconds after the pretreatment process.
１．前処理工程
　基材にインク１を付与する直前に、塗布バーを用いて前処理液１を基材上に塗工した。塗工は、前処理液１の塗工量を１．５ｇ／ｍ２として行った。次いで、基材上に塗工された前処理液１を下記の条件で乾燥させた。 1. Pretreatment step Immediately before the ink 1 was applied to the substrate, the pretreatment liquid 1 was applied onto the substrate using an application bar. The coating was performed with the coating amount of the pretreatment liquid 1 being 1.5 g / m 2 . Next, the pretreatment liquid 1 coated on the substrate was dried under the following conditions.
<<条件（送風乾燥）>>
　風速：１５ｍ／秒
　温度及び加熱方法：基材の表面温度（基材の前処理液１が塗工された側の温度）が６０℃となるように基材の背面（基材の前処理液１が塗工されていない側の表面）から接触型平面ヒーターを用いて加熱した。
　送風領域：４５０ｍｍ（乾燥時間：０．７秒） << Condition (fan drying) >>
Wind speed: 15 m / sec Temperature and heating method: Back surface of substrate (pretreatment liquid for substrate) so that surface temperature of substrate (temperature on the side on which substrate pretreatment liquid 1 is applied) is 60 ° C. The surface was heated using a contact type flat heater from the surface of the side where 1 was not coated.
Air blowing area: 450 mm (drying time: 0.7 seconds)
２．画像形成工程
　基材の前処理液１が塗工された側に、下記の条件でインク１（マゼンタインクＭ１、ブラックインクＫ１、シアンインクＣ１、及びイエローインクＹ１）をシングルパス方式で吐出し、多色画像を形成した。具体的には、前処理液１が塗工された基材の前処理液塗工面に、下記の条件で各色のインクを付与（打滴）して画像を形成した。 2. Image formation step Ink 1 (magenta ink M1, black ink K1, cyan ink C1, and yellow ink Y1) is ejected on the side of the base material on which the pretreatment liquid 1 has been applied, under the following conditions. A multicolor image was formed. Specifically, ink of each color was applied (droplet ejected) on the pretreatment liquid-coated surface of the substrate coated with the pretreatment liquid 1 under the following conditions to form an image.
<<条件>>
　ヘッド：１，２００ｄｐｉ（dots per inch）／２０ｉｎｃｈ幅のピエゾフルラインヘッドが４色分配置されたヘッド
　吐出液滴量：２．４ｐＬ（ピコリットル）
　駆動周波数：３０ｋＨｚ（基材搬送速度：６３５ｍｍ／秒） << Condition >>
Head: Head with 1,200 dpi (dots per inch) / 20 inch wide piezo full line heads for 4 colors Discharge droplet volume: 2.4 pL (picoliter)
Drive frequency: 30 kHz (base material conveyance speed: 635 mm / second)
　次に、基材の前処理液塗工面に付与されたインク１を下記の条件で乾燥させた。 Next, the ink 1 applied to the pretreatment liquid coating surface of the substrate was dried under the following conditions.
<<条件（送風乾燥）>>
　風速：１５ｍ／秒
　温度及び加熱方法：基材の表面温度（基材のインク１が付与された側の温度）を６０℃となるように基材の背面（基材のインク１が付与されていない側の表面）から接触型平面ヒーターを用いて加熱した。
　送風領域：６４０ｍｍ（乾燥時間：１秒間） << Condition (fan drying) >>
Wind speed: 15 m / sec Temperature and heating method: Substrate back surface (base material ink 1 is applied) so that the substrate surface temperature (temperature of the base material ink 1 application side) is 60 ° C. The non-side surface was heated using a contact type flat heater.
Air blowing area: 640 mm (drying time: 1 second)
３．加熱定着工程
　次いで、インク１の付与により形成された画像を、シリコンゴムローラ（硬度：５０°、ニップ幅：５ｍｍ）を用いて下記の条件で加熱定着し、基材上に画像が形成された試料を得た。 3. Heat Fixing Step Next, an image formed by applying ink 1 was heat fixed using a silicon rubber roller (hardness: 50 °, nip width: 5 mm) under the following conditions, and a sample on which an image was formed on a substrate Got.
<<条件>>
　ローラ温度：９０℃
　圧力：０．８ＭＰａ << Condition >>
Roller temperature: 90 ° C
Pressure: 0.8 MPa
４．オーバーコート工程
　上記の加熱定着工程を終了した後、ローラーコーター（製品名：Ｄｉｇｉ　Ｃｏａｔｅｒ　ＰＯＤ、（株）トヨテック）を用い、画像が形成された基材の画像形成面の全体にオーバーコート液（オーバーコート液１～１９のいずれか）を、上記のローラーコーターにより塗工することによって、基材の画像形成面に対して後処理を施し、画像サンプルを作製した。後処理は、オーバーコート液を、塗工量を４．０ｇ／ｍ２として基材の画像形成面に塗工することにより行った。 4). Overcoat process After the above heat fixing process is completed, an overcoat solution (overcoat) is applied to the entire image forming surface of the substrate on which an image is formed using a roller coater (product name: Digi Coater POD, Toyotec Co., Ltd.). Any one of the coating liquids 1 to 19) was applied by the roller coater described above, so that the image forming surface of the substrate was post-treated to prepare an image sample. The post-treatment was performed by coating the overcoat solution on the image forming surface of the substrate with a coating amount of 4.0 g / m 2 .
　次に、基材の画像形成面に塗工したオーバーコート液を下記の条件で乾燥させた。 Next, the overcoat solution coated on the image forming surface of the substrate was dried under the following conditions.
<<条件>>
　温度及び加熱方法：基材の表面温度が４０℃となるように基材の表面から赤外線ヒーターを用いて加熱した。
　搬送速度：３０ｍ／分 << Condition >>
Temperature and heating method: Heating was performed from the surface of the substrate using an infrared heater so that the surface temperature of the substrate was 40 ° C.
Conveying speed: 30m / min
－評価－
　上記のようにして作製した画像サンプルに対して、以下の評価を行った。評価結果を下記の表４に示す。 -Evaluation-
The following evaluations were performed on the image samples produced as described above. The evaluation results are shown in Table 4 below.
（１）光沢性
　ＢＹＫガードナー・トリグロスメーター（（株）東洋精機製作所）を用い、画像サンプルにおける基材の画像形成面の光沢度を、オーバーコート液の塗工方向に対して平行な方向と垂直な方向とから測定し、それぞれ６０°反射角での光沢度を求めた。 (1) Glossiness Using a BYK Gardner Trigloss Meter (Toyo Seiki Seisakusho Co., Ltd.), the glossiness of the image forming surface of the base material in the image sample is parallel to the coating direction of the overcoat liquid. Measured from the vertical direction, the glossiness at 60 ° reflection angle was obtained.
（評価１）
　光沢度の値として、オーバーコート液の塗工方向に対して平行な方向の測定値と垂直な方向の測定値との平均値を算出し、算出された平均値を光沢値として、下記の評価基準に従って評価した。 (Evaluation 1)
Calculate the average value of the measured value in the direction parallel to the coating direction of the overcoat liquid and the measured value in the direction perpendicular to the coating direction of the overcoat solution as the gloss value, and use the calculated average value as the gloss value to evaluate the following: Evaluation was made according to criteria.
～評価基準～
　５：光沢度の平均値が６０以上である。
　４：光沢度の平均値が５０以上６０未満である。
　３：光沢度の平均値が４０以上５０未満であり、高光沢なオーバーコート面が得られた。
　２：光沢度の平均値が３０以上４０未満であり、高光沢なオーバーコート面が得られていない。
　１：光沢度の平均値が３０未満であった。 -Evaluation criteria-
5: The average glossiness is 60 or more.
4: Average glossiness is 50 or more and less than 60.
3: The average glossiness was 40 or more and less than 50, and a highly glossy overcoat surface was obtained.
2: The average glossiness is 30 or more and less than 40, and a high gloss overcoat surface is not obtained.
1: The average value of glossiness was less than 30.
（評価２）
　更に、光沢均一性を評価する指標として、オーバーコート液の塗工方向に対して、平行な方向の光沢度の測定値ｐと、垂直な方向の光沢度の測定値ｑと、の差の絶対値を求め、下記の評価基準に従って評価した。 (Evaluation 2)
Further, as an index for evaluating the gloss uniformity, the absolute difference between the measured value p of the glossiness in the direction parallel to the coating direction of the overcoat liquid and the measured value q of the glossiness in the vertical direction is absolute. The value was determined and evaluated according to the following evaluation criteria.
～評価基準～
　５：平行な方向の測定値ｐと垂直な方向の測定値ｑとの差の絶対値が０以上５未満である。
　４：平行な方向の測定値ｐと垂直な方向の測定値ｑとの差の絶対値が５以上１０未満である。
　３：平行な方向の測定値ｐと垂直な方向の測定値ｑとの差の絶対値が１０以上１５未満であり、実用上許容範囲である。
　２：平行な方向の測定値ｐと垂直な方向の測定値ｑとの差の絶対値が１５以上２０未満であり、平行方向と垂直方向の光沢差が明確に視認され、実用上許容されない程度である。
　１：平行な方向の測定値ｐと垂直な方向の測定値ｑとの差の絶対値が２０以上である。 -Evaluation criteria-
5: The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 0 or more and less than 5.
4: The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 5 or more and less than 10.
3: The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 10 or more and less than 15, which is practically acceptable.
2: The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 15 or more and less than 20, and the difference in gloss between the parallel direction and the vertical direction is clearly visually recognized and is not practically acceptable. It is.
1: The absolute value of the difference between the measured value p in the parallel direction and the measured value q in the vertical direction is 20 or more.
（２）画像の耐擦性
　オーバーコート工程における塗工及び乾燥を終了した直後１０分以内に、未使用のコート紙（製品名：ボンアイボリー、米坪：３１０ｇ／ｍ２、王子製紙（株）；被記録材料）を用い、画像サンプルにおける基材の画像形成面を、２４０ｇ／ｃｍ２の加重を掛けて１０回擦った。その後、擦られた部分を目視で観察し、下記の評価基準に従って評価した。 (2) Scratch resistance of the image Within 10 minutes immediately after finishing the coating and drying in the overcoat process, an unused coated paper (product name: Bon Ivory, US tsubo: 310 g / m 2 , Oji Paper Co., Ltd.) Recording material), and the image forming surface of the base material in the image sample was rubbed 10 times under a load of 240 g / cm 2 . Thereafter, the rubbed portion was visually observed and evaluated according to the following evaluation criteria.
～評価基準～
　５：擦られた部分は、擦られていない部分と変わらず、全く傷が認められなかった。
　４：擦られた部分の表面が僅かに傷付いているが、画像として損傷なく実用上問題ない。
　３：擦られた部分の表面が僅かに剥がれ、極細い傷がみられたが、実用上支障を来たさない程度である。
　２：擦られた部分の表面が剥がれ、傷が目立ち、実用上支障を来たす程度である。
　１：擦られた部分の画像が剥がれ、部分的にコート紙の白地が露出し、実用上問題となる程度である。 -Evaluation criteria-
5: The rubbed portion was not different from the rubbed portion, and no scratch was observed.
4: Although the surface of the rubbed portion is slightly scratched, there is no damage as an image and there is no practical problem.
3: The surface of the rubbed part was slightly peeled off and very fine scratches were observed, but this is not a problem in practical use.
2: The surface of the rubbed part is peeled off, scratches are conspicuous, and impede practically.
1: The image of the rubbed part is peeled off, and the white background of the coated paper is partially exposed, causing a practical problem.
（３）画像の耐水性
　オーバーコート工程における塗工及び乾燥を終了した直後１０分以内に、画像サンプルにおける基材の画像形成面に、イオン交換水を１滴垂らし、５秒後にワイプタオルを用いて拭き取った。その後、拭き取った部分を目視で観察し、下記の評価基準に従って評価した。 (3) Water resistance of the image Within 10 minutes immediately after finishing the coating and drying in the overcoat process, a drop of ion-exchanged water is dropped on the image forming surface of the substrate in the image sample, and a wipe towel is used after 5 seconds. Wiped off. Thereafter, the wiped portion was visually observed and evaluated according to the following evaluation criteria.
～評価基準～
　５：イオン交換水が付着した部分は、イオン交換水が付着していない部分と変わらず、全く変化がみられない。
　４：イオン交換水が付着した部分の輪郭部に僅かに跡が付いたが、実用上問題ない。
　３：イオン交換水が付着した部分の全面に跡が弱く付いたが、実用上許容される程度である。
　２：イオン交換水が付着した部分に跡が明確に付いており、実用上支障を来たす程度である。
　１：イオン交換水が付着した部分のオーバーコートが無くなり、実用上許容できない。 -Evaluation criteria-
5: The part to which ion exchange water is attached is not different from the part to which ion exchange water is not attached, and no change is observed.
4: Although the trace part of the part of the part which ion-exchange water adhered adhered a little, there is no problem practically.
3: A trace was weakly attached to the entire surface of the portion to which the ion-exchanged water was adhered, but it was practically acceptable.
2: The mark is clearly attached to the portion where the ion exchange water is adhered, and it is practically hindered.
1: The overcoat of the part to which ion-exchange water adhered is lost, and it is unacceptable practically.
（４）オーバーコート液の保存安定性
　６０℃にて２週間保管したオーバーコート液を用いて、上記と同様の操作を行い、画像サンプルを作製した。保管後のオーバーコート液を塗工して作製した画像サンプルと、保管前のオーバーコート液を塗工して作製した画像サンプルと比較し、下記の評価基準に従って評価した。 (4) Storage stability of overcoat solution Using the overcoat solution stored at 60 ° C for 2 weeks, the same operation as described above was performed to prepare an image sample. An image sample prepared by applying the overcoat solution after storage and an image sample prepared by applying the overcoat solution before storage were evaluated according to the following evaluation criteria.
～評価基準～
　５：保管前のオーバーコート液を塗工して作製した画像サンプルと同様に、異常は認められなかった。
　４：保管前のオーバーコート液を塗工して作製した画像サンプルと比較すると、極薄いスジ跡が僅かにみられるが、実用上問題ない。
　３：保管前のオーバーコート液を塗工して作製した画像サンプルと比較して、極薄いスジ跡が多くみられるが、実用上支障を来たさない程度である。
　２：保管前のオーバーコート液を塗工して作製した画像サンプルと比較して、明確なスジ状の外観異常が多く、実用上支障を来たす。
　１：保管前のオーバーコート液を塗工して作製した画像サンプルと比較して、明確なスジ状の外観異常が非常に多く、実用性が全く無い。 -Evaluation criteria-
5: No abnormality was observed as in the case of the image sample prepared by applying the overcoat solution before storage.
4: Compared with an image sample prepared by applying an overcoat solution before storage, a very thin streak trace is seen, but there is no practical problem.
3: Compared with an image sample prepared by applying an overcoat solution before storage, ultrathin streak traces are often observed, but are practically satisfactory.
2: Compared with an image sample prepared by applying an overcoat solution before storage, there are many clear streak-like appearance abnormalities, which hinders practical use.
1: Compared with an image sample prepared by applying an overcoat solution before storage, the appearance of clear streak-like appearance is very large and there is no practicality at all.
Figure JPOXMLDOC01-appb-T000012
 
Figure JPOXMLDOC01-appb-T000012
 
　表４に示すように、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子を含むオーバーコート液を含む実施例１～実施例１６のインクセットを用いて作製された画像サンプルは、非常に良好な光沢性を有していた。また、式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子を含むオーバーコート液は、保存安定性が良好であった。
　さらに、実施例１～実施例１６のインクセットを用いて作製された画像サンプルは、耐擦性及び耐水性も良好であった。 As shown in Table 4, the ink sets of Examples 1 to 16 including an overcoat solution containing resin particles having a group represented by the formula (1) and not having a carboxy group were used. The image sample prepared in this way had very good gloss. Moreover, the overcoat liquid containing the particle | grains of the resin which has group represented by Formula (1), and does not have a carboxy group was favorable in storage stability.
Furthermore, the image samples produced using the ink sets of Examples 1 to 16 also had good abrasion resistance and water resistance.
　一方、カルボキシ基を有さないが、式（１）で表される基も有さない樹脂の粒子を含むオーバーコート液を含む比較例１及び比較例２のインクセットを用いて作製された画像サンプルは、実施例１等のインクセットを用いて作製された画像サンプルと比較して、光沢性が劣る傾向を示した。また、カルボキシ基を有さないが、式（１）で表される基も有さない樹脂の粒子を含む比較例１におけるオーバーコート液（Ｎｏ．１７）及び比較例２におけるオーバーコート液（Ｎｏ．１８）は、実施例１等におけるオーバーコート液と比較して、保存安定性が顕著に劣っていた。
　式（１）で表される基を有するが、カルボキシ基も有する樹脂の粒子を含むオーバーコート液を有する比較例３のインクセットを用いて作製された画像サンプルは、実施例１等のインクセットを用いて作製された画像サンプルと比較して、光沢性が顕著に劣っていた。 On the other hand, images prepared using the ink sets of Comparative Example 1 and Comparative Example 2 containing an overcoat liquid containing resin particles that do not have a carboxy group but also have no group represented by Formula (1) The sample tended to be less glossy than the image sample produced using the ink set of Example 1 or the like. Further, the overcoat liquid (No. 17) in Comparative Example 1 and the overcoat liquid (No.) in Comparative Example 2 containing resin particles that do not have a carboxy group but do not have the group represented by Formula (1). .18) was significantly inferior in storage stability as compared to the overcoat solution in Example 1 and the like.
An image sample produced using the ink set of Comparative Example 3 having an overcoat solution containing resin particles having a group represented by the formula (1) but also having a carboxy group is an ink set of Example 1 or the like. The gloss was remarkably inferior as compared with the image sample produced using.
　２０１７年３月２９日に出願された日本国特許出願２０１７－０６６１１５号の開示は、その全体が参照により本明細書に取り込まれる。
　本明細書に記載された全ての文献、特許出願、及び技術規格は、個々の文献、特許出願、及び技術規格が参照により取り込まれることが具体的に、かつ、個々に記された場合と同程度に、本明細書中に参照により取り込まれる。 The disclosure of Japanese Patent Application No. 2017-066115 filed on Mar. 29, 2017 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards described in this specification are specifically and individually incorporated by reference as if individual documents, patent applications, and technical standards were incorporated by reference. To the extent it is incorporated herein by reference.

Claims (6)

  1. 　着色剤及び水を含むインク組成物と、
    　酸及び水を含む前処理液と、
    　下記の式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子、及び水を含むオーバーコート液と、
    を有するインクセット。
    Figure JPOXMLDOC01-appb-C000001
     
    　式（１）中、Ａは、炭素数２又は３のアルキレン基を表し、Ｒは、水素原子又は炭素数１～２０の炭化水素基を表し、ｍは、３以上４０以下の整数を表す。     An ink composition comprising a colorant and water;
    A pretreatment liquid containing acid and water;
    An overcoat solution comprising a resin particle having a group represented by the following formula (1) and not having a carboxy group, and water;
    An ink set.
    Figure JPOXMLDOC01-appb-C000001

    In formula (1), A represents an alkylene group having 2 or 3 carbon atoms, R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and m represents an integer of 3 to 40.
  2. 　前記粒子に含まれる前記樹脂中の、前記式（１）で表される基の合計含有量は、前記樹脂１ｇ当たり、０．０５ｇ以上０．５０ｇ以下である請求項１に記載のインクセット。 The ink set according to claim 1, wherein the total content of the group represented by the formula (1) in the resin contained in the particles is 0.05 g or more and 0.50 g or less per 1 g of the resin.
  3. 　前記粒子に含まれる前記樹脂は、下記の式（２）で表される少なくとも１種の構成単位と、下記の式（３）及び下記の式（４）からなる群より選ばれる少なくとも１種の構成単位と、を含む請求項１又は請求項２に記載のインクセット。
    Figure JPOXMLDOC01-appb-C000002
     
    　式（２）中、Ａは、炭素数２又は３のアルキレン基を表し、Ｒは、水素原子又は炭素数１～２０の炭化水素基を表し、Ｒ１は、水素原子又はメチル基を表し、ｍは、３以上４０以下の整数を表す。
    　式（３）中、Ｒ２は、水素原子又はメチル基を表し、Ｒ３は、炭素数１～２０の炭化水素基を表す。     The resin contained in the particles includes at least one structural unit represented by the following formula (2), at least one selected from the group consisting of the following formula (3) and the following formula (4). The ink set according to claim 1, comprising a structural unit.
    Figure JPOXMLDOC01-appb-C000002

    In formula (2), A represents an alkylene group having 2 or 3 carbon atoms, R represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R 1 represents a hydrogen atom or a methyl group, m represents an integer of 3 to 40.
    In formula (3), R 2 represents a hydrogen atom or a methyl group, and R 3 represents a hydrocarbon group having 1 to 20 carbon atoms.
  4. 　前記式（２）におけるｍは、６以上２０以下の整数を表す請求項３に記載のインクセット。 The ink set according to claim 3, wherein m in the formula (2) represents an integer of 6 or more and 20 or less.
  5. 　前記粒子は、前記式（１）で表される基を有するノニオン性界面活性剤を含む請求項１～請求項４のいずれか１項に記載のインクセット。 The ink set according to any one of claims 1 to 4, wherein the particles include a nonionic surfactant having a group represented by the formula (1).
  6. 　被記録材料に、酸及び水を含む前処理液を付与する工程と、
    　前記被記録材料の前記前処理液の付与面に、着色剤及び水を含むインク組成物を付与して画像を形成する工程と、
    　前記被記録材料の前記画像が形成された側の少なくとも一部に、前記式（１）で表される基を有し、かつ、カルボキシ基を有さない樹脂の粒子、及び水を含むオーバーコート液を付与する工程と、
    を有する画像形成方法。     Applying a pretreatment liquid containing acid and water to the recording material;
    Forming an image by applying an ink composition containing a colorant and water to the application surface of the pretreatment liquid of the recording material;
    An overcoat comprising a resin particle having a group represented by the formula (1) and not having a carboxy group on at least a part of the recording material on which the image is formed, and water Applying a liquid;
    An image forming method comprising:
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