WO2019150644A1 - Photocurable ink composition for ink-jet recording and ink set - Google Patents

Photocurable ink composition for ink-jet recording and ink set Download PDF

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Publication number
WO2019150644A1
WO2019150644A1 PCT/JP2018/034285 JP2018034285W WO2019150644A1 WO 2019150644 A1 WO2019150644 A1 WO 2019150644A1 JP 2018034285 W JP2018034285 W JP 2018034285W WO 2019150644 A1 WO2019150644 A1 WO 2019150644A1
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WO
WIPO (PCT)
Prior art keywords
meth
ink composition
mass
group
acrylic monomer
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Application number
PCT/JP2018/034285
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French (fr)
Japanese (ja)
Inventor
雄二郎 原田
欣正 光本
Original Assignee
マクセルホールディングス株式会社
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Filing date
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Application filed by マクセルホールディングス株式会社 filed Critical マクセルホールディングス株式会社
Priority to JP2019568571A priority Critical patent/JP7309623B2/en
Priority to CN201880088278.5A priority patent/CN111684025B/en
Publication of WO2019150644A1 publication Critical patent/WO2019150644A1/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
    • C09D11/38—Inkjet printing inks characterised by non-macromolecular additives other than solvents, pigments or dyes
    • 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

Definitions

  • the present invention relates to a photocurable ink composition for ink jet recording and an ink set.
  • Examples of the ink composition for ink jet recording include an ink composition for forming an image by irradiating an active energy ray such as ultraviolet rays, and an image formed by penetrating into a recording medium and removing the solvent by drying or the like.
  • Examples of the ink composition to be formed (hereinafter, the former may be referred to as a photocurable ink composition for ink jet recording and the latter may be referred to as a solvent ink jet recording ink composition). Since the photocurable ink composition for ink jet recording forms a polymer by light irradiation and is excellent in drying property, generally, the formed image is excellent in coating film strength compared with the ink composition for solvent type ink jet recording. In addition, it has an advantage that it is excellent in transferability for a design image and is suitable for high-speed printing.
  • the property of ejecting ink droplets stably without causing clogging at the nozzles of the ink jet head in order to obtain an image with even better transferability (ejection stability) Is required.
  • Discharge stability is required as an important property particularly in high-speed printing.
  • Patent Document 1 describes that a photocurable ink composition for ink jet recording having excellent curability has skin irritation. It is desired to satisfy all four properties of such an ink composition, such as ejection stability, safety, coating film adhesion, and coating film strength.
  • the present invention has been made in view of the above problems, and its purpose is photocuring capable of forming a coating film having excellent safety and excellent discharge stability in high-speed printing, and having excellent adhesion and strength.
  • An ink composition for ink jet recording is provided.
  • Another object of the present invention is to provide an ink set containing such a photocurable ink composition for ink jet recording.
  • a vinyl ether group-containing (meth) acrylic acid ester represented by: At least one monofunctional monomer selected from the group consisting of acrylamide monomers and monofunctional (meth) acrylic monomers; A polyfunctional (meth) acrylic monomer, The content of the monofunctional monomer is 1% by mass or more and 9% by mass or less, The content of the polyfunctional (meth) acrylic monomer is 5% by mass or more and 50% by mass or less, The glass transition temperature of the polymer of monofunctional (meth) acrylic monomer is 30 ° C. or higher, A photocurable ink composition for ink jet recording, wherein the polyfunctional (meth) acrylic monomer polymer has a glass transition temperature of 30 ° C. or higher.
  • the content of the polymerizable compound having a primary skin irritation index of less than 2 is 3 to 35 parts by mass with respect to 100 parts by mass of the polymerizable compound, [1] or [2] The photocurable ink composition for ink jet recording described in 1.
  • the polyfunctional (meth) acrylic monomer includes a bifunctional (meth) acrylic monomer having a chain structure and a bifunctional (meth) acrylic monomer having an alicyclic structure.
  • the monofunctional (meth) acrylic monomer includes at least one selected from the group consisting of isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclic trimethylolpropane formal acrylate, and isobornyl methacrylate.
  • the photocurable ink composition for ink jet recording according to any one of [1] to [6].
  • the polyfunctional (meth) acrylic monomer includes dicyclopentanyl diacrylate, methyl-1,5-pentanediol diacrylate, dipropylene glycol diacrylate, neopentyl glycol hydroxypivalate ester diacrylate, 1,10 -The above-mentioned [1] to [7], comprising at least one selected from the group consisting of decanediol diacrylate, tripropylene glycol diacrylate, neopentyl glycol propylene oxide diacrylate and 1,9-nonanediol diacrylate
  • the photocurable ink composition for inkjet recording according to any one of the above.
  • the content of the vinyl ether group-containing (meth) acrylic acid ester is 20% by mass or more and 50% by mass or less, for photocurable inkjet recording according to any one of [1] to [8] Ink composition.
  • An ink set comprising the photocurable ink composition for ink jet recording according to any one of [1] to [10].
  • the present invention it is possible to provide a photocurable ink composition for ink jet recording that has excellent safety and excellent ejection stability in high-speed printing, and can form a coating film having excellent adhesion and strength. Moreover, according to this invention, the ink set containing such an ink composition for photocurable inkjet recording can be provided.
  • acryl and methacryl may be referred to as “(meth) acryl”.
  • “system” is added after the compound name, and the compound and its derivatives may be collectively referred to.
  • the polymer name is expressed by adding “system” after the compound name, the repeating unit of the polymer is derived from the compound or its derivative, or it is chemically modified after the polymerization to the repeating unit derived from the compound or its derivative. It means that the polymer is subjected to.
  • An ink composition for ink jet recording according to an embodiment of the present invention (hereinafter sometimes referred to as an ink composition) is used in a single-pass ink jet recording apparatus.
  • the ink composition contains a polymerizable compound and a photopolymerization initiator.
  • the polymerizable compound includes a vinyl ether group-containing (meth) acrylic acid ester, a monofunctional monomer, and a polyfunctional monomer.
  • Vinyl ether group-containing (meth) acrylic acid esters are represented by the general formula (I).
  • the monofunctional monomer is at least one selected from the group consisting of acrylamide monomers and monofunctional (meth) acrylic monomers.
  • the content of the monofunctional monomer is 1% by mass or more and 9% by mass or less.
  • the content rate of a polyfunctional (meth) acryl monomer is 5 mass% or more and 50 mass% or less.
  • the glass transition temperature of the polymer of the monofunctional (meth) acrylic monomer is 30 ° C. or higher, and the glass transition temperature of the polymer of the polyfunctional (meth) acrylic monomer is 30 ° C. or higher.
  • a single-pass inkjet recording apparatus includes a line head that covers the entire recording medium in a direction perpendicular to the conveyance direction of the recording medium. This ink jet recording apparatus moves the recording medium only once in the transport direction with respect to the fixed line head, and ejects ink droplets from the nozzles of the line head in conjunction with this movement. Form. Therefore, the single-pass inkjet recording apparatus can perform high-speed printing and can improve productivity.
  • the discharge method is preferably a piezo method.
  • the photopolymerization initiator absorbs active energy rays and initiates a photopolymerization reaction (chain polymerization reaction).
  • the photopolymerization initiator include acylphosphine oxide compounds, alkylphenone compounds, and thioxanthone compounds.
  • acylphosphine oxide compounds examples include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide.
  • examples of commercially available acylphosphine oxide compounds include “IRGACURE (registered trademark) TPO” and “IRGACURE (registered trademark) 819” manufactured by BASF.
  • alkylphenone compounds examples include 2,2-dimethoxy-1,2-diphenylethane-1-one and 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one. Is mentioned.
  • Examples of commercially available alkylphenone compounds include “IRGACURE (registered trademark) 651” and “IRGACURE (registered trademark) 907” manufactured by BASF.
  • thioxanthone compound examples include thioxanthone, 2,4-dimethylthioxanthone, 2-chlorothioxanthone, 2-ethylthioxanthone, and 1-chloro-4-propoxythioxanthone.
  • the content of the photopolymerization initiator is preferably 5 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the ink composition from the viewpoint of efficiently proceeding the photopolymerization reaction. The following is more preferable.
  • a polymerizable compound is a compound that can form a polymer by a polymerization reaction.
  • the polymerizable compound is at least one monofunctional selected from the group consisting of vinyl ether group-containing (meth) acrylic acid esters represented by the general formula (I), acrylamide monomers and monofunctional (meth) acrylic monomers.
  • the glass transition temperature of the polymer of a monofunctional (meth) acryl monomer is 30 ° C. or higher.
  • the glass transition temperature of the polymer of a polyfunctional (meth) acryl monomer is 30 ° C. or higher.
  • the content of the polymerizable compound is preferably 60 to 85% by mass in the total ink composition.
  • the viscosity of the ink composition can be set to 10.5 mPa ⁇ s or less, and the primary skin irritation index 2 described below can be set.
  • the vinyl ether group-containing (meth) acrylic acid ester represented by the general formula (I) may be referred to as (meth) acrylic acid ester (I).
  • divalent organic residue having 2 to 20 carbon atoms examples include, for example, an alkylene group having 2 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, and 6 to 10 carbon atoms.
  • the bivalent aromatic group of these is mentioned.
  • a divalent organic residue having 2 to 20 carbon atoms may be substituted.
  • An alkylene group having 2 to 20 carbon atoms is linear or branched and unsubstituted.
  • Examples of the alkyl group having 2 to 20 carbon atoms include ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, and hexadecylene group.
  • the alkylene group having 2 to 20 carbon atoms is preferably an alkylene group having 2 to 9 carbon atoms, substituted with an oxoalkylene group having 1 to 8 carbon atoms or any one having 2 to 4 oxygen atoms.
  • the alkylene group having 9 to 15 carbon atoms and the alkylene group having 2 to 6 carbon atoms are more preferable.
  • An alkylene group having 2 to 9 carbon atoms is linear or branched and unsubstituted.
  • Examples of the alkyl group having 2 to 9 carbon atoms include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, and a nonylene group.
  • An oxoalkylene group having 1 to 8 carbon atoms is linear or branched and unsubstituted.
  • the oxoalkylene group having 1 to 8 carbon atoms is a substituent in which one —CH 2 — in the alkylene group having 2 to 9 carbon atoms is substituted with —O—.
  • An alkylene group having 9 to 15 carbon atoms is linear or branched and unsubstituted.
  • Examples of the alkylene group having 9 to 15 carbon atoms include a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tridodecylene group, a tetradecylene group, a tetradecylene group, and a pentadecylene group.
  • alkylene group having 2 to 6 carbon atoms is linear or branched and unsubstituted.
  • alkyl group having 2 to 6 carbon atoms include an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group.
  • the cycloalkylene group having 3 to 20 carbon atoms is cyclic and unsubstituted.
  • Examples of the cycloalkylene group having 3 to 20 carbon atoms include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, and a cyclohexane group.
  • Examples include an undecylene group and a cyclohexadecylene group.
  • the cycloalkylene group having 3 to 20 carbon atoms may be a cycloalkylene group having 3 to 20 carbon atoms which may be substituted with a plurality of alkyl groups having 1 to 3 carbon atoms.
  • the alkyl group having 1 to 3 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, a propyl group, and an isopropyl group.
  • the divalent aromatic group having 6 to 10 carbon atoms is cyclic and unsubstituted.
  • Examples of the divalent aromatic group having 6 to 10 carbon atoms include a phenylene group and a naphthylylene group.
  • the divalent aromatic group having 6 to 10 carbon atoms is a divalent aromatic group having 6 to 10 carbon atoms which may be substituted with a plurality of alkyl groups having 1 to 3 carbon atoms. There may be.
  • Examples of the monovalent organic residue having 1 to 11 carbon atoms include, for example, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and 6 to 10 carbon atoms.
  • a monovalent aromatic group is mentioned.
  • An alkyl group having 1 to 10 carbon atoms is linear or branched and unsubstituted.
  • Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group.
  • the alkyl group having 1 to 10 carbon atoms is preferably an alkyl group having 1 to 3 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms which may be substituted with a phenyl group, and a methyl group. More preferred are an ethyl group and a benzyl group.
  • the monovalent aromatic group having 6 to 10 carbon atoms which may be substituted is preferably a phenyl group.
  • An alkyl group having 1 to 3 carbon atoms is synonymous with an alkyl group having 1 to 3 carbon atoms in a cycloalkylene group having 3 to 20 carbon atoms.
  • a cycloalkyl group having 3 to 10 carbon atoms is cyclic and unsubstituted.
  • Examples of the cycloalkyl group having 3 to 10 carbon atoms include a cyclopentane group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.
  • the monovalent aromatic group having 6 to 10 carbon atoms is cyclic and unsubstituted.
  • Examples of the 1-value aromatic group having 6 to 10 carbon atoms include a phenyl group and a naphthyl group.
  • Examples of (meth) acrylic acid esters (I) include vinyloxyalkyl (meth) acrylate, vinyloxycycloalkyl (meth) acrylate, alkylvinyloxyalkyl (meth) acrylate, and vinyl (meth) acrylate. Loxyalkylcycloalkylalkyl, vinyloxyalkylalkylalkyl (meth) acrylate, vinyloxyalkoxyalkyl (meth) acrylate, vinyloxyalkoxyalkoxyalkyl (meth) acrylate, and vinyloxyalkoxyalkoxyalkoxyalkyl (meth) acrylate Is mentioned. These (meth) acrylic acid esters (I) may be used individually by 1 type, and may be used in combination of 2 or more type.
  • vinyloxyalkyl (meth) acrylate examples include 2-vinyloxyethyl (meth) acrylate, 2-vinyloxypropyl (meth) acrylate, 4-vinyloxybutyl (meth) acrylate, and 2-methacrylic acid 2- Vinyloxybutyl is mentioned.
  • vinyloxycycloalkyl (meth) acrylate examples include vinyloxycyclohexyl (meth) acrylate.
  • alkylvinyloxyalkyl (meth) acrylate examples include 2-methyl-3-vinyloxypropyl (meth) acrylate and 1-methyl-2-vinyloxypropyl (meth) acrylate.
  • Examples of (meth) acrylic acid vinyloxyalkylcycloalkylalkyl include, for example, (meth) acrylic acid 3-vinyloxymethylcyclohexylmethyl.
  • Examples of (meth) acrylic acid vinyloxyalkylarylalkyl include p-vinyloxymethylphenylmethyl (meth) acrylate.
  • Examples of (meth) acrylic acid vinyloxyalkoxyalkyl include 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA), 2- (2-vinyloxyethoxy) ethyl methacrylate (VEEM), and (meth) acrylic.
  • Examples include 2- (vinyloxyisopropoxy) propyl 2-acid and 2- (vinyloxyisopropoxy) isopropyl (meth) acrylate.
  • Examples of (meth) acrylic acid vinyloxyalkoxyalkoxyalkyl include, for example, (meth) acrylic acid vinyloxyethoxyethoxyethyl.
  • (Vinyloxyalkoxyalkoxyalkoxyalkoxyalkyl (meth) acrylate includes, for example, vinyloxyethoxyethoxyethoxyethyl (meth) acrylate).
  • (meth) acrylic acid esters (I) it has low viscosity, low odor, can suppress irritation to the skin, has high flash point, is excellent in reactivity and curability, and is formed by curing.
  • (Meth) acrylic acid 2- (2-vinyloxyethoxy) ethyl is preferred because of excellent adhesion of the coating film.
  • the content of the (meth) acrylic acid esters (I) can reduce the viscosity of the ink, and from the viewpoint of improving the reactivity, the coating film strength, and the adhesion, is 20% by mass or more and 60% by mass in the ink composition. % Or less, more preferably 20% by mass or more and 50% by mass or less, further preferably 30% by mass or more and 50% by mass or less, and more preferably 35% by mass or more and 50% by mass or less. Particularly preferred is 35% by mass or more and 45% by mass or less.
  • the monofunctional monomer has one polymerizable moiety (for example, an ethylenic double bond) in one molecule.
  • the monofunctional monomer is at least one selected from the group consisting of acrylamide monomers and monofunctional (meth) acrylic monomers.
  • the content of the monofunctional monomer is 1% by mass or more and 9% by mass or less in the ink composition.
  • the glass transition temperature Tg of the polymer of a monofunctional (meth) acryl monomer is 30 ° C. or higher.
  • the monofunctional monomer has a relatively low viscosity, and the glass transition temperature Tg of the polymer of the monofunctional (meth) acrylic monomer is relatively high.
  • the ink composition contains a monofunctional monomer at a content of 1% by mass or more and 9% by mass or less, it serves as a diluent for the (meth) acrylic acid esters (I) and the polyfunctional (meth) acrylic monomer. It is possible to provide an ink composition that functions, can form a coating film having excellent ejection stability and safety and excellent strength, that is, having three properties in a well-balanced manner. From the viewpoint of further improving the above three properties, the content of the monofunctional monomer is preferably 7% by mass or more and 9% by mass or less in the ink composition, and more preferably 5% by mass or more and 9% by mass or less. preferable.
  • the primary skin irritation index (Primary Irritation Index: PII value) is a physical property value indicating skin irritation. The larger the PII value, the stronger the irritation to the skin, indicating that the compound requires careful handling.
  • acrylamide monomer examples include dimethylacrylamide, diethylacrylamide, 2-hydroxyethylacrylamide, dimethylaminopropylacrylamide, and acryloylmorpholine (ACMO).
  • acrylamide monomers having a cyclic structure are preferable, and acryloylmorpholine is more preferable.
  • Examples of the monofunctional (meth) acrylic monomer include a monofunctional (meth) acrylic monomer having a chain structure or a cyclic structure.
  • the monofunctional (meth) acrylic monomer having a chain structure here does not have a cyclic structure in its molecular structure, but has a linear structure or a branched structure.
  • the monofunctional (meth) acrylic monomer having a cyclic structure has a cyclic structure in its molecular structure and may further have a chain structure.
  • the monofunctional (meth) acrylic monomer preferably has a cyclic structure from the viewpoint that the polymer of the monofunctional (meth) acrylic monomer has a glass transition temperature of 30 ° C. or higher.
  • Examples of the monofunctional (meth) acrylic monomer having a cyclic structure include monocyclic alicyclic (meth) acrylates, bicyclic alicyclic (meth) acrylates, and heterocyclic (meth) acrylates.
  • Examples of the monocyclic alicyclic (meth) acrylate include cycloalkyl (meth) acrylate (more specifically, 3,3,5-trimethylcyclohexyl acrylate (TMCHA) and the like).
  • bicyclic alicyclic (meth) acrylate examples include isobornyl acrylate (IBOA), isobornyl methacrylate, norbornyl (meth) acrylate, amadantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate.
  • IBOA isobornyl acrylate
  • norbornyl (meth) acrylate norbornyl (meth) acrylate
  • amadantyl (meth) acrylate examples of the heterocyclic (meth) acrylate
  • CTFA cyclic trimethylolpropane formal acrylate
  • isobornyl acrylate (IBOA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), and cyclic trimethylolpropane formal acrylate (CTFA)
  • isobornyl methacrylate At least one selected from the group consisting of isobornyl acrylate (IBOA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), and cyclic trimethylolpropane formal acrylate (CTFA) At least one is more preferable.
  • the glass transition temperature Tg of the polymer of monofunctional (meth) acrylic monomer is 30 ° C. or higher from the viewpoint of improving the coating film strength.
  • the glass transition temperature of the monofunctional (meth) acrylic monomer is preferably 30 ° C. or more and 90 ° C. or less, and 40 ° C. or more, from the viewpoint of improving ejection stability and safety while maintaining excellent coating strength. More preferably, it is 90 ° C. or lower.
  • the polymer of a monofunctional (meth) acrylic monomer is a polymer obtained by polymerizing a monofunctional (meth) acrylic monomer alone. That is, it means that the polymer consists essentially of a repeating unit derived from one monofunctional (meth) acrylic monomer.
  • the polymer substantially consists of a repeating unit derived from one monofunctional (meth) acrylic monomer means that the repeating unit derived from one monofunctional (meth) acrylic monomer is composed of all repeating units constituting the polymer. It means 99 mol% or more.
  • the polyfunctional (meth) acrylic monomer has two or more polymerizable moieties (for example, ethylenic double bonds) in one molecule.
  • polyfunctional (meth) acrylic monomers include bifunctional (meth) acrylic monomers, trifunctional (meth) acrylic monomers, tetrafunctional (meth) acrylic monomers, and pentafunctional (meth) acrylic monomers.
  • the polyfunctional (meth) acrylic monomer may have a chain structure or an alicyclic structure.
  • the polyfunctional (meth) acrylic monomer having a chain structure does not have a cyclic structure in its molecular structure, but has a linear structure or a branched structure.
  • the polyfunctional (meth) acrylic monomer having an alicyclic structure has an alicyclic structure in its molecular structure and may further have a chain structure.
  • the polyfunctional (meth) acrylic monomer is a bifunctional (meth) from the viewpoint that the polymer of the polyfunctional (meth) acrylic monomer has a glass transition temperature of 30 ° C. or more and improves the safety of the ink composition.
  • An acrylic monomer is preferable, and it is more preferable to include a bifunctional (meth) acrylic monomer having a chain structure and a bifunctional (meth) acrylic monomer having an alicyclic structure, and a bifunctional (meth) having a chain structure. More preferably, it contains only acrylic monomers.
  • bifunctional (meth) acrylic monomer having a chain structure examples include alkanediol diacrylate (more specifically, methyl-1,5-pentanediol diacrylate (MPDDA), 1,9-nonanediol diacrylate).
  • alkanediol diacrylate more specifically, methyl-1,5-pentanediol diacrylate (MPDDA), 1,9-nonanediol diacrylate).
  • Examples of the bifunctional (meth) acrylic monomer having a cyclic structure include dicyclopentanyl diacrylate (DCPDA).
  • DCPDA dicyclopentanyl diacrylate
  • polyfunctional (meth) acrylic monomers other than bifunctional are trifunctional (meth) such as propoxylated trimethylolpropane tri (meth) acrylate, glycerin propoxytri (meth) acrylate or pentaerythritol tri (meth) acrylate.
  • trifunctional (meth) such as propoxylated trimethylolpropane tri (meth) acrylate, glycerin propoxytri (meth) acrylate or pentaerythritol tri (meth) acrylate.
  • examples include acrylic monomers, tetrafunctional (meth) acrylic monomers such as pentaerythritol tetra (meth) acrylate, and pentafunctional (meth) acrylic monomers such as dipentaerythritol hydroxypenta (meth) acrylate.
  • dicyclopentanyl diacrylate DCPDA
  • MPDDA methyl-1,5-pentanediol diacrylate
  • DPGDA dipropylene glycol diacrylate
  • HPNDA 1,10-decanediol diacrylate
  • TPGDA tripropylene glycol diacrylate
  • NPPGODA neopentyl glycol propylene oxide diacrylate
  • 1,9-nonanediol diacrylate 1,9ND-A
  • dipropylene glycol diacrylate DPGDA
  • neopentyl glycol hydroxypivalate diacrylate HPND
  • TPGDA tripropylene glycol diacrylate
  • NPPDA neopentyl glycol propylene oxide diacrylate
  • the glass transition temperature Tg of the polymer of the polyfunctional (meth) acrylic monomer is 30 ° C. or higher from the viewpoint of improving the coating film strength.
  • the glass transition temperature Tg of the polyfunctional (meth) acrylic monomer is preferably 30 ° C. or higher and 200 ° C. or lower from the viewpoint of improving ejection stability and safety while maintaining excellent coating strength.
  • the temperature is more preferably 150 ° C. or lower.
  • the polymer of the polyfunctional (meth) acrylic monomer is a polymer obtained by polymerizing the polyfunctional (meth) acrylic monomer alone. That is, it means that the polymer consists essentially of repeating units derived from one kind of polyfunctional (meth) acrylic monomer.
  • the polymer substantially consists of a repeating unit derived from one kind of polyfunctional (meth) acrylic monomer means that the repeating unit derived from one kind of polyfunctional (meth) acrylic monomer is composed of all repeating units constituting the polymer. It means 99 mol% or more.
  • the content of the polyfunctional (meth) acrylic monomer is 5% by mass or more and 50% by mass in the ink composition from the viewpoint of improving the ejection stability and safety of the ink composition and improving the coating film strength. It is preferable that they are 10 mass% or more and 40 mass% or less.
  • the content of the polyfunctional (meth) acrylic monomer is preferably 5% by mass or more and 20% by mass or less, preferably 10% by mass or more and 15% by mass or less when the ink composition contains a white pigment as a pigment. It is more preferable.
  • the content of the polyfunctional (meth) acrylic monomer is such that the ink composition includes a pigment other than white as a pigment (more specifically, a cyan, magenta, yellow, or black pigment). In this case, it is preferably 25% by mass or more and 50% by mass or less, more preferably 30% by mass or more and 45% by mass or less, and more preferably 30% by mass or more and 40% by mass or less.
  • the ink composition may further contain an optional component as necessary in addition to the polymerizable compound and the photopolymerization initiator.
  • an optional component for example, surfactant (surface tension adjusting agent), coloring material, polymerization inhibitor, dispersant, organic solvent, fixing resin, leveling agent, antifoaming agent, antioxidant, pH adjusting agent, Examples include charge imparting agents, bactericides, antiseptics, deodorants, charge control agents, wetting agents, and ultraviolet absorbers.
  • surfactant surface tension adjusting agent
  • coloring material for example, coloring material, polymerization inhibitor, dispersant, organic solvent, fixing resin, leveling agent, antifoaming agent, antioxidant, pH adjusting agent
  • Examples include charge imparting agents, bactericides, antiseptics, deodorants, charge control agents, wetting agents, and ultraviolet absorbers.
  • the ink composition may contain a surfactant.
  • the surfactant include silicone compounds.
  • the silicone compound for example, a silicone compound having a dimethylsiloxane structure is preferable, and a polyether-modified polydimethylsiloxane is more preferable.
  • examples of commercially available surfactants include BYK-350, 352, 354, 355, 358N, 361N, 381N, 381, 392, BYK-300, 302, 306, 307, 310, 315, and 320 manufactured by BYK Chemie.
  • UV3500, UV3510, and UV3570 "Tegorad” manufactured by Tegochemy -2100, 2200, 2250, 2500, and 2700 ”, and“ TEGO® Glide 100, 110, 130, 403, 406, 410, 411, 415, 432, 435, 440, 450, and Evonik Degussa ” 482 "etc. It is but not limited thereto.
  • These surfactants may be used individually by 1 type, and may be used in combination of 2 or more type.
  • the ink composition can be sufficiently wetted and spread on the recording medium to maintain good compatibility even when the ink composition is stored for a long period of time. This is because reproducibility can be maintained.
  • the content of the surfactant is preferably 0.01 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the ink composition from the viewpoint of improving the wettability of the ink composition of the present invention with respect to the recording medium.
  • the ink composition may contain a polymerization inhibitor.
  • the polymerization inhibitor include hydroquinone compounds, catechol compounds, and phenol compounds.
  • the hydroquinone compound include hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, tert-butylhydroquinone, and ditert-butylhydroquinone.
  • the catechol-based compound include catechol, methyl catechol, and tert-butyl catechol.
  • phenolic compounds include phenol, 3,5-ditert-butyl-4-hydroxytoluene (butylhydroxytoluene (BHT)), cresol, and methoquinone.
  • the content of the polymerization inhibitor is 0.05 parts by mass or more and 5 parts by mass with respect to 100 parts by mass of the ink composition from the viewpoint of achieving both the storage stability of the ink composition of the present invention and the curability in the single pass method.
  • the content is preferably 0.20 parts by mass or more and 2 parts by mass or less, and more preferably 0.1 parts by mass or more and 1 part by mass or less.
  • colorant examples include pigments and dyes. From the viewpoint of improving the weather resistance of the formed image, a pigment (more specifically, an organic pigment, an inorganic pigment, or the like) is preferable.
  • black colorant examples include carbon black.
  • Commercially available black colorants include, for example, Toka Black manufactured by Tokai Carbon; HCF, MCF, RCF, LFF, SCF manufactured by Mitsubishi Chemical; Color Black, Special Black, and Printex manufactured by Degussa Huls Colombia's Raven; Cabot's Monarch and Legal.
  • cyan colorants include copper phthalocyanine compounds, anthraquinone compounds, and basic dye lake compounds.
  • cyan colorants include C.I. I. Pigment blue (1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, or 66).
  • yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and arylamide compounds.
  • yellow colorants include C.I. I. Pigment Yellow (1, 3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 138, 147, 151 154, 155, 168, 174, 175, 176, 180, 181, 185, 191, 194, and 214).
  • magenta colorant examples include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.
  • magenta colorant examples include C.I. I. Pigment Red (2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 168, 177 184, 185, 202, 206, 220, 221 or 254).
  • white colorants include white organic pigments (more specifically, Pigment White 6, 18, 21 etc.), white inorganic pigments (more specifically, basic lead carbonate, oxidation). Zinc, titanium oxide, strontium titanate, etc.).
  • the dispersion average particle diameter of the pigment is preferably 20 to 250 nm, and more preferably 50 to 230 nm.
  • the content of the colorant is preferably from 0.5 parts by weight to 25 parts by weight, more preferably from 1.0 parts by weight to 20 parts by weight, with respect to 100 parts by weight of the ink composition. It is still more preferable that it is 0.0 mass part or more and 15 mass parts or less.
  • the ink composition may contain a dispersant (more specifically, a pigment dispersion or the like).
  • a dispersant include polyvinyl alcohol, acrylic acid resin, styrene-acrylic acid resin, and vinyl acetate resin.
  • acrylic resin include polyacrylic acid, acrylic acid-acrylonitrile copolymer, and acrylic acid-alkyl acrylate copolymer.
  • styrene-acrylic acid resin examples include a styrene-acrylic acid copolymer, a styrene-methacrylic acid copolymer, and a styrene-acrylic acid-acrylic acid alkyl ester copolymer.
  • vinyl acetate resin examples include a vinyl acetate-ethylene copolymer and a vinyl acetate-maleic acid ester copolymer.
  • the content of the dispersing agent is from 0.1 to 3 parts by mass with respect to 100 parts by mass of the ink composition from the viewpoint of improving the dispersion stability of the ink composition and exhibiting the same quality as the initial stage even after long-term aging. Or less, more preferably 0.5 parts by mass or more and 1.5 parts by mass or less.
  • the ink composition may contain an organic solvent for the purpose of adjusting the viscosity of the ink composition.
  • the ink composition preferably contains substantially no organic solvent.
  • the ink composition does not need to contain an organic solvent for the purpose of dilution, it is not necessary to heat the ink composition excessively for the purpose of adjusting the viscosity when discharging the ink composition.
  • the ink composition does not need to contain an organic solvent for the purpose of dilution, the viscosity of the ink composition increases due to the volatilization of the organic solvent in the ink composition during storage or use of the ink composition. Etc.
  • the ink composition preferably does not substantially contain an organic solvent from the viewpoint of further improving ejection stability.
  • the content of the organic solvent is preferably 3 parts by mass or less, more preferably 1 part by mass or less, and still more preferably 0 parts by mass with respect to 100 parts by mass of the ink composition.
  • the organic solvent include aromatic hydrocarbons, aliphatic hydrocarbons, ethers, and ketones.
  • the PII value of the ink composition is preferably less than 2, more preferably less than 2.00, and even more preferably less than 1.70.
  • a method for calculating the PII value of the ink composition is described in Examples.
  • the content of the polymerization compound having a primary skin irritation index of less than 2 is 3 with respect to 100 parts by mass of the polymerizable compound (total mass of the polymerizable compound of 100 parts by mass) from the viewpoint of improving the safety of the ink composition.
  • the mass is preferably 35 parts by mass or more and more preferably 5 parts by mass or more and 32 parts by mass or less.
  • the ink composition is suitable for use in an image-forming product that touches a human hand, particularly when the primary skin irritation index PII value is less than 2.
  • the ink composition can be used as an ink composition for food packaging recording for recording on the surface of food packaging as a label. Examples of the label include a product name, a product component, a manufacturer name, a manufacturing date, a lot number, and a note.
  • a method for preparing the ink composition As a method for preparing the ink composition, a conventionally known preparation method can be used. Hereinafter, a suitable preparation method when the ink composition contains a pigment as a colorant will be described. Using a disperser, colorants, a part of the polymerizable compound, and optional components (more specifically, pigment dispersants, etc.) are premixed (premixed) as necessary, and each component is mixed. A primary dispersion is prepared by dissolving or dispersing.
  • disperser examples include a disperser, a container drive medium mill (more specifically, a ball mill, a centrifugal mill, a planetary ball mill, and the like), a high-speed rotating mill (more specifically, a sand mill, etc.), and a medium agitation mill (more specifically, More specifically, a stirring tank type mill or the like may be mentioned.
  • a container drive medium mill more specifically, a ball mill, a centrifugal mill, a planetary ball mill, and the like
  • a high-speed rotating mill more specifically, a sand mill, etc.
  • a medium agitation mill more specifically, More specifically, a stirring tank type mill or the like may be mentioned.
  • the resulting primary dispersion is then mixed with the remaining polymerizable compound, photopolymerization initiator, surfactant (surface tension modifier), and additives (more specifically, gelling prevention) as required. Agent) and mix uniformly using a stirrer.
  • the stirrer include a disperser, a three-one motor, a homogenizer, and a magnetic stirrer.
  • an ink composition can be obtained.
  • the ink composition may be mixed using a mixer such as a line mixer.
  • the ink composition may be mixed using a disperser such as a bead mill and a high-pressure jet mill for the purpose of further reducing the particles in the ink composition.
  • the ink set includes a photocurable ink composition for inkjet recording.
  • the ink set includes a color ink composition for photocurable inkjet recording of a plurality of colors (for example, cyan, magenta, yellow, black, and white).
  • the photocurable ink composition for ink jet recording is, for example, a photocurable ink composition for ink jet recording containing a coloring material.
  • pigment dispersion Black pigment dispersion
  • Pigment Carbon black pigment (“Special Black 250” manufactured by Degussa 15.0 parts Pigment dispersant Solsperse 32000 (manufactured by Lubrizol) 6.0 parts Bifunctional acrylic monomer Dipropylene glycol diacrylate (DPGDA) 79.0 parts
  • DPGDA Dipropylene glycol diacrylate
  • Above materials Pigment, pigment dispersant, and bifunctional acrylic monomer were charged into a plastic bottle, and the contents of the plastic bottle were agitated using a high speed mixer to obtain a mill base. (Toyo Seiki Co., Ltd.) was used to disperse the mill base for 2 hours to obtain a black pigment dispersion.
  • Carbon black pigment (“Special Black 250” manufactured by Degussa) as a black pigment
  • copper phthalocyanine pigment (“P-BFS” manufactured by Clariant) as a cyan pigment
  • quinacridone pigment (BASF as a magenta pigment) “RT-355D”) and a disazo pigment as a yellow pigment (“4GC” manufactured by Clariant), respectively, in the same manner as the preparation of the black pigment dispersion, respectively, cyan pigment dispersion, magenta A pigment dispersion and a yellow pigment dispersion were prepared.
  • White pigment dispersion 15.0 parts of carbon black pigment (“Special Black 250” manufactured by Degussa) as a black pigment was changed to 50.0 parts of titanium oxide pigment (“CR-60” manufactured by Ishihara Sangyo Co., Ltd.) as a white pigment.
  • a white pigment dispersion was prepared in the same manner as the black pigment dispersion except that the amount of dipropylene glycol diacrylate added was changed from 79.0 parts to 45.0 parts.
  • ink compositions (A-2) to (A-7) and Ink Compositions (B-1) to (B-9) were prepared.
  • the monofunctional monomer was changed from 9 parts of isobornyl acrylate (IBOA) to 5 parts of isobornyl acrylate (IBOA) and 4 parts of acryloylmorpholine (ACMO). It was prepared in the same manner as the ink composition (A-1).
  • the black pigment dispersion was changed to a cyan pigment dispersion, and the monofunctional monomer was changed from 9 parts of isobornyl acrylate (IBOA) to 3,3,5-trimethylcyclohexyl acrylate (TMCHA).
  • IBOA isobornyl acrylate
  • TMCHA 3,3,5-trimethylcyclohexyl acrylate
  • HPNDA neopentyl glycol hydroxypivalate ester diacrylate
  • TPGDA tripropylene glycol diacrylate
  • NPGPODA neopentyl glycol propylene oxide diacrylate
  • the coating film was irradiated with ultraviolet rays under the condition of an integrated light quantity of 200 mJ / cm 2 to be cured, thereby obtaining a cured product.
  • the obtained cured product was peeled from the glass substrate to obtain a measurement sample.
  • the glass transition temperature (unit: temperature) of the measurement sample was measured using a thermogravimetric measurement device (“TG-GDA” manufactured by Mac Science).
  • the glass transition temperature of the measured measurement sample was defined as the glass transition temperature of a polymer of monofunctional (meth) acrylic monomer or polyfunctional (meth) acrylic monomer.
  • the glass transition temperatures obtained are summarized in Tables 1 and 2.
  • the measurement conditions were a nitrogen atmosphere, a temperature increase rate of 10 ° C./min, and a measurement temperature range of ⁇ 100 to 180 ° C.
  • the column “Tg” indicates the glass transition temperature of the polymer of each component.
  • the alphabet in the column “component” indicates the abbreviation or model number of the component shown in Table 3.
  • the column “viscosity” indicates the viscosity of each component at 25 ° C.
  • the columns “Example 1” to “Example 7” and the columns “Comparative Example 1” to “Comparative Example 9” indicate the ink compositions (A-1) to (A-7) and the ink composition (B-1), respectively. ) To (B-9) indicates the content (unit: part) of each component.
  • Table 3 shows details of the components of the ink composition.
  • the ink composition When the viscosity of the ink composition at 25 ° C. is 10.5 mPa ⁇ s or less, the ink composition is stably ejected from the nozzles of the inkjet head under the standard use conditions (usually 40 ° C.) of the inkjet recording apparatus. Because.
  • the ink composition was ejected from an inkjet head and applied onto a substrate (white PET) to form a coating film.
  • This inkjet head is an inkjet head mounted on a single-pass inkjet recording apparatus.
  • an ultraviolet LED (“NCCU001E” manufactured by Nichia Corporation)
  • the coating film is irradiated with ultraviolet light so that the total irradiation light quantity becomes 300 mJ / cm 2 , the coating film is cured, and the coating film is formed on the substrate. (Film thickness 3 ⁇ m) was formed.
  • the ink composition was ejected from an inkjet head and applied onto a substrate (white PET) to form a coating film.
  • This inkjet head is an inkjet head mounted on a single-pass inkjet recording apparatus.
  • an ultraviolet LED (“NCCU001E” manufactured by Nichia Corporation)
  • the coating film is irradiated with ultraviolet light so that the total irradiation light quantity becomes 300 mJ / cm 2 , the coating film is cured, and the coating film is formed on the substrate. (Film thickness 3 ⁇ m) was formed.
  • the ink compositions (A-1) to (A-7) contained a polymerizable compound and a photopolymerization initiator.
  • the polymerizable compound contained (meth) acrylic acid esters (I), a monofunctional monomer, and a polyfunctional (meth) acrylic monomer.
  • the monofunctional monomer was at least one of a monofunctional (meth) acryl monomer and an acrylamide monomer.
  • the content of the monofunctional monomer was a numerical value included in the range of 1% to 9%.
  • the content of the polyfunctional (meth) acrylic monomer was a value included in the range of 10% to 40%.
  • the glass transition temperature of the polymer of the monofunctional (meth) acrylic monomer was 30 ° C. or higher.
  • the glass transition temperature of the polymer of the polyfunctional (meth) acrylic monomer was 30 ° C. or higher.
  • the ink compositions (A-1) to (A-7) had a viscosity of 10.5 mPa ⁇ s or less and a PII value of 1.83 or less.
  • the evaluation of the coating strength was S (particularly good) or A (good).
  • the ink compositions (B-1) to (B-2) did not contain (meth) acrylic acid esters (I).
  • the content of the monofunctional monomer was greater than 9%.
  • the polyfunctional (meth) acrylic monomer content was less than 10% or greater than 40%.
  • the glass transition temperature Tg of the polymer of the monofunctional (meth) acrylic monomer was less than 30 ° C.
  • the glass transition temperature Tg of the polyfunctional (meth) acrylic monomer polymer was less than 30 ° C.
  • the viscosity is 10.5 mPa ⁇ s or less, the PII value is less than 2.00, the adhesion evaluation S (particularly good) or A (Good) and coating strength evaluation S (particularly good) or A (good) were not satisfied.
  • the ink compositions (A-1) to (A-7) are superior in ink ejection stability and safety to the ink compositions (B-1) to (B-9) and can be obtained. It is clear that the adhesion and strength of the coating film are excellent.
  • the photocurable ink composition for ink jet recording of the present invention can be suitably used as an ink set for ink jet recording together with other photocurable ink composition for ink jet recording.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Ink Jet Recording Methods And Recording Media Thereof (AREA)
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Abstract

A photocurable ink composition for ink-jet recording which is for use in single-pass ink-jet devices and which comprises polymerizable compounds and a photopolymerization initiator, wherein the polymerizable compounds comprise a vinyl-ether-group-containing (meth)acrylic ester compound represented by the general formula CH2=CR1-COOR2-O-CH=CH-R3 (I), one or more monofunctional monomers comprising an acrylamide-based monomer and/or a monofunctional (meth)acrylic monomer, and a polyfunctional (meth)acrylic monomer, the content of the monofunctional monomers being 1-9 mass% and the content of the polyfunctional (meth)acrylic monomer being 5-50 mass%, and the polymers of the monofunctional monomers and of the polyfunctional monomer each having a glass transition temperature of 30°C or higher.

Description

光硬化型インクジェット記録用インク組成物およびインクセットPhotocurable ink composition for ink jet recording and ink set
　本発明は、光硬化型インクジェット記録用インク組成物およびインクセットに関する。 The present invention relates to a photocurable ink composition for ink jet recording and an ink set.
　インクジェット記録用インク組成物としては、たとえば、紫外線のような活性エネルギー線の照射により塗布膜を硬化させて画像を形成するインク組成物、および記録媒体へ浸透させ溶剤を乾燥等で除去し画像を形成するインク組成物が挙げられる（以下、前者を光硬化型インクジェット記録用インク組成物と記載し、後者を溶剤型インクジェット記録用インク組成物と記載することがある）。光硬化型インクジェット記録用インク組成物は光照射により重合体を形成しかつ乾燥性に優れるため、一般的に、溶剤型インクジェット記録用インク組成物に比べ、形成される画像は塗膜強度に優れ、設計画像に対する転写性に優れ、かつ高速印刷に適するとの利点を有する。 Examples of the ink composition for ink jet recording include an ink composition for forming an image by irradiating an active energy ray such as ultraviolet rays, and an image formed by penetrating into a recording medium and removing the solvent by drying or the like. Examples of the ink composition to be formed (hereinafter, the former may be referred to as a photocurable ink composition for ink jet recording and the latter may be referred to as a solvent ink jet recording ink composition). Since the photocurable ink composition for ink jet recording forms a polymer by light irradiation and is excellent in drying property, generally, the formed image is excellent in coating film strength compared with the ink composition for solvent type ink jet recording. In addition, it has an advantage that it is excellent in transferability for a design image and is suitable for high-speed printing.
特開２０１０－２０９１９８号公報JP 2010-209198 A
　光硬化型インクジェット記録用インク組成物に対しては、転写性がさらに優れる画像を得るために、インクジェットヘッドのノズルにおいて目詰まりを起こさずインク液滴を安定的に吐出する性質（吐出安定性）が要求されている。吐出安定性は、特に高速印刷において重要な性質として求められている。 For photocurable ink compositions for ink jet recording, the property of ejecting ink droplets stably without causing clogging at the nozzles of the ink jet head in order to obtain an image with even better transferability (ejection stability) Is required. Discharge stability is required as an important property particularly in high-speed printing.
　光硬化型インクジェット記録用インク組成物は、通常、光重合開始剤とエチレン性二重結合を有する重合性化合物とを含むため、臭気、皮膚刺激等を有する。特許文献１には、硬化性に優れる光硬化型インクジェット記録用インク組成物ほど、皮膚刺激性を有することが記載されている。このようなインク組成物の吐出安定性、安全性、塗膜の密着性および塗膜強度の４つの性質をすべて満足することが望まれている。 Since the photocurable ink composition for ink jet recording usually contains a photopolymerization initiator and a polymerizable compound having an ethylenic double bond, it has odor, skin irritation, and the like. Patent Document 1 describes that a photocurable ink composition for ink jet recording having excellent curability has skin irritation. It is desired to satisfy all four properties of such an ink composition, such as ejection stability, safety, coating film adhesion, and coating film strength.
　本発明は、上記課題に鑑みてなされたものであり、その目的は、優れた安全性および高速印刷における優れた吐出安定性を有し、密着性および強度に優れる塗膜を形成可能な光硬化型インクジェット記録用インク組成物を提供することである。また、本発明の別の目的は、そのような光硬化型インクジェット記録用インク組成物を含むインクセットを提供することである。 The present invention has been made in view of the above problems, and its purpose is photocuring capable of forming a coating film having excellent safety and excellent discharge stability in high-speed printing, and having excellent adhesion and strength. An ink composition for ink jet recording is provided. Another object of the present invention is to provide an ink set containing such a photocurable ink composition for ink jet recording.
　発明者らは、鋭意検討の結果、本発明をするに至った。
　すなわち、本発明は、以下の態様を提供するものである。
［１］シングルパス方式のインクジェット記録装置に用いる光硬化型インクジェット記録用インク組成物であって、
　重合性化合物と光重合開始剤とを含有し、
　前記重合性化合物は、
　下記一般式（Ｉ）：
　　ＣＨ２＝ＣＲ１－ＣＯＯＲ２－Ｏ－ＣＨ＝ＣＨ－Ｒ３・・・（Ｉ）
（前記一般式（Ｉ）中、Ｒ１は水素原子またはメチル基を表し、Ｒ２は炭素原子数２以上２０以下の２価の有機残基を表し、Ｒ３は水素原子または炭素原子数１以上１１以下の１価の有機残基を表す）
で表されるビニルエーテル基含有（メタ）アクリル酸エステル類と、
　アクリルアミド系モノマーおよび単官能（メタ）アクリルモノマーからなる群から選択される少なくとも１種の単官能モノマーと、
　多官能（メタ）アクリルモノマーとを含み、
　前記単官能モノマーの含有率は、１質量％以上９質量％以下であり、
　前記多官能（メタ）アクリルモノマーの含有率は、５質量％以上５０質量％以下であり、
　単官能（メタ）アクリルモノマーの重合体のガラス転移温度が３０℃以上であり、
　多官能（メタ）アクリルモノマーの重合体のガラス転移温度が３０℃以上である、光硬化型インクジェット記録用インク組成物。
［２］一次皮膚刺激性インデックスは２未満である、前記［１］に記載の光硬化型インクジェット記録用インク組成物。
［３］一次皮膚刺激性インデックスが２未満である重合性化合物の含有量は、前記重合性化合物１００質量部に対して３質量部以上３５質量部以下である、前記［１］または［２］に記載の光硬化型インクジェット記録用インク組成物。
［４］前記多官能（メタ）アクリルモノマーは、鎖状構造または脂環式構造を有する、前記［１］～［３］のいずれかに記載の光硬化型インクジェット記録用インク組成物。
［５］前記多官能（メタ）アクリルモノマーは、鎖状構造を有する二官能（メタ）アクリルモノマーと、脂環式構造を有する二官能（メタ）アクリルモノマーとを含む、前記［１］～［４］のいずれかに記載の光硬化型インクジェット記録用インク組成物。
［６］前記アクリルアミド系モノマーはアクリロイルモルフォリンである、前記［１］～［５］のいずれかに記載の光硬化型インクジェット記録用インク組成物。
［７］前記単官能（メタ）アクリルモノマーは、イソボルニルアクリレート、３，３，５－トリメチルシクロヘキシルアクリレート、環状トリメチロールプロパンホルマールアクリレートおよびイソボルニルメタクリレートからなる群から選択される少なくとも１種を含む、前記［１］～［６］のいずれかに記載の光硬化型インクジェット記録用インク組成物。
［８］前記多官能（メタ）アクリルモノマーは、ジシクロペンタニルジアクリレート、メチル－１，５－ペンタンジオールジアクリレート、ジプロピレングリコールジアクリレート、ネオペンチルグリコールヒドロキシピバリン酸エステルジアクリレート、１，１０－デカンジオールジアクリレート、トリプロピレングリコールジアクリレート、ネオペンチルグリコールプロピレンオキシドジアクリレートおよび１，９－ノナンジオールジアクリレートからなる群から選択される少なくとも１種を含む、前記［１］～［７］のいずれかに記載の光硬化型インクジェット記録用インク組成物。
［９］前記ビニルエーテル基含有（メタ）アクリル酸エステル類の含有率は、２０質量％以上５０質量％以下である、前記［１］～［８］のいずれかに記載の光硬化型インクジェット記録用インク組成物。
［１０］食品包装記録用である、前記［１］～［９］のいずれかに記載の光硬化型インクジェット記録用インク組成物。
［１１］前記［１］～［１０］のいずれかに記載の光硬化型インクジェット記録用インク組成物を含む、インクセット。 As a result of intensive studies, the inventors have arrived at the present invention.
That is, the present invention provides the following aspects.
[1] A photocurable inkjet recording ink composition for use in a single-pass inkjet recording apparatus,
Containing a polymerizable compound and a photopolymerization initiator,
The polymerizable compound is
The following general formula (I):
CH 2 = CR 1 —COOR 2 —O—CH═CH—R 3 (I)
(In the general formula (I), R 1 represents a hydrogen atom or a methyl group, R 2 represents a divalent organic residue having 2 to 20 carbon atoms, and R 3 represents a hydrogen atom or 1 carbon atom. Represents a monovalent organic residue of 11 or less)
A vinyl ether group-containing (meth) acrylic acid ester represented by:
At least one monofunctional monomer selected from the group consisting of acrylamide monomers and monofunctional (meth) acrylic monomers;
A polyfunctional (meth) acrylic monomer,
The content of the monofunctional monomer is 1% by mass or more and 9% by mass or less,
The content of the polyfunctional (meth) acrylic monomer is 5% by mass or more and 50% by mass or less,
The glass transition temperature of the polymer of monofunctional (meth) acrylic monomer is 30 ° C. or higher,
A photocurable ink composition for ink jet recording, wherein the polyfunctional (meth) acrylic monomer polymer has a glass transition temperature of 30 ° C. or higher.
[2] The photocurable ink jet recording ink composition according to [1], wherein the primary skin irritation index is less than 2.
[3] The content of the polymerizable compound having a primary skin irritation index of less than 2 is 3 to 35 parts by mass with respect to 100 parts by mass of the polymerizable compound, [1] or [2] The photocurable ink composition for ink jet recording described in 1.
[4] The photocurable inkjet recording ink composition according to any one of [1] to [3], wherein the polyfunctional (meth) acrylic monomer has a chain structure or an alicyclic structure.
[5] The polyfunctional (meth) acrylic monomer includes a bifunctional (meth) acrylic monomer having a chain structure and a bifunctional (meth) acrylic monomer having an alicyclic structure. 4] The photocurable ink composition for inkjet recording according to any one of the above.
[6] The photocurable inkjet recording ink composition according to any one of [1] to [5], wherein the acrylamide monomer is acryloylmorpholine.
[7] The monofunctional (meth) acrylic monomer includes at least one selected from the group consisting of isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclic trimethylolpropane formal acrylate, and isobornyl methacrylate. The photocurable ink composition for ink jet recording according to any one of [1] to [6].
[8] The polyfunctional (meth) acrylic monomer includes dicyclopentanyl diacrylate, methyl-1,5-pentanediol diacrylate, dipropylene glycol diacrylate, neopentyl glycol hydroxypivalate ester diacrylate, 1,10 -The above-mentioned [1] to [7], comprising at least one selected from the group consisting of decanediol diacrylate, tripropylene glycol diacrylate, neopentyl glycol propylene oxide diacrylate and 1,9-nonanediol diacrylate The photocurable ink composition for inkjet recording according to any one of the above.
[9] The content of the vinyl ether group-containing (meth) acrylic acid ester is 20% by mass or more and 50% by mass or less, for photocurable inkjet recording according to any one of [1] to [8] Ink composition.
[10] The photocurable inkjet recording ink composition according to any one of [1] to [9], which is for food packaging recording.
[11] An ink set comprising the photocurable ink composition for ink jet recording according to any one of [1] to [10].
　本発明によれば、優れた安全性および高速印刷における優れた吐出安定性を有し、密着性および強度に優れる塗膜を形成可能な光硬化型インクジェット記録用インク組成物を提供することができる。また、本発明によれば、そのような光硬化型インクジェット記録用インク組成物を含むインクセットを提供することができる。 According to the present invention, it is possible to provide a photocurable ink composition for ink jet recording that has excellent safety and excellent ejection stability in high-speed printing, and can form a coating film having excellent adhesion and strength. . Moreover, according to this invention, the ink set containing such an ink composition for photocurable inkjet recording can be provided.
　以下、本発明の実施形態について詳細に説明する。なお、本明細書において、アクリルおよびメタクリルを「（メタ）アクリル」と称する場合がある。また、化合物名の後に「系」を付けて、化合物及びその誘導体を包括的に称する場合がある。化合物名の後に「系」を付けて重合体名を表す場合には、重合体の繰返し単位が化合物若しくはその誘導体に由来すること、または化合物若しくはその誘導体に由来する繰返し単位に重合後に化学修飾等を施した重合体であることを意味する。 Hereinafter, embodiments of the present invention will be described in detail. In this specification, acryl and methacryl may be referred to as “(meth) acryl”. In addition, “system” is added after the compound name, and the compound and its derivatives may be collectively referred to. When the polymer name is expressed by adding “system” after the compound name, the repeating unit of the polymer is derived from the compound or its derivative, or it is chemically modified after the polymerization to the repeating unit derived from the compound or its derivative. It means that the polymer is subjected to.
＜光硬化型インクジェット記録用インク組成物＞
　本発明の実施形態に係るインクジェット記録用インク組成物（以下、インク組成物と記載することがある）は、シングルパス方式のインクジェット記録装置に用いられる。インク組成物は、重合性化合物と光重合開始剤とを含有する。重合性化合物は、ビニルエーテル基含有（メタ）アクリル酸エステル類と、単官能モノマーと、多官能モノマーとを含む。ビニルエーテル基含有（メタ）アクリル酸エステル類は、一般式（Ｉ）で表される。単官能モノマーは、アクリルアミド系モノマーおよび単官能（メタ）アクリルモノマーからなる群から選択される少なくとも１種である。単官能モノマーの含有率は、１質量％以上９質量％以下である。多官能（メタ）アクリルモノマーの含有率は、５質量％以上５０質量％以下である。単官能（メタ）アクリルモノマーの重合体のガラス転移温度が３０℃以上であり、多官能（メタ）アクリルモノマーの重合体のガラス転移温度が３０℃以上である。 <Photocurable ink composition for inkjet recording>
An ink composition for ink jet recording according to an embodiment of the present invention (hereinafter sometimes referred to as an ink composition) is used in a single-pass ink jet recording apparatus. The ink composition contains a polymerizable compound and a photopolymerization initiator. The polymerizable compound includes a vinyl ether group-containing (meth) acrylic acid ester, a monofunctional monomer, and a polyfunctional monomer. Vinyl ether group-containing (meth) acrylic acid esters are represented by the general formula (I). The monofunctional monomer is at least one selected from the group consisting of acrylamide monomers and monofunctional (meth) acrylic monomers. The content of the monofunctional monomer is 1% by mass or more and 9% by mass or less. The content rate of a polyfunctional (meth) acryl monomer is 5 mass% or more and 50 mass% or less. The glass transition temperature of the polymer of the monofunctional (meth) acrylic monomer is 30 ° C. or higher, and the glass transition temperature of the polymer of the polyfunctional (meth) acrylic monomer is 30 ° C. or higher.
［１．シングルパス方式］
　シングルパス方式のインクジェット記録装置は、記録媒体の搬送方向に対して垂直方向の記録媒体全域をカバーするラインヘッドを備える。このインクジェット記録装置は、固定されたラインヘッドに対して記録媒体を搬送方向に一回だけ移動させ、この移動に連動してラインヘッドのノズルからインク液滴を吐出する動作で記録媒体上に画像を形成する。このため、シングルパス方式のインクジェット記録装置は高速印刷が可能であり、生産性を向上させることができる。吐出方式は、ピエゾ方式が好ましい。 [1. Single pass method]
A single-pass inkjet recording apparatus includes a line head that covers the entire recording medium in a direction perpendicular to the conveyance direction of the recording medium. This ink jet recording apparatus moves the recording medium only once in the transport direction with respect to the fixed line head, and ejects ink droplets from the nozzles of the line head in conjunction with this movement. Form. Therefore, the single-pass inkjet recording apparatus can perform high-speed printing and can improve productivity. The discharge method is preferably a piezo method.
［２．光重合開始剤］
　本明細書において、光重合開始剤は、活性エネルギー線を吸収し光重合反応（連鎖重合反応）を開始させる。光重合開始剤としては、たとえば、アシルホスフィンオキサイド系化合物、アルキルフェノン系化合物、およびチオキサントン系化合物が挙げられる。 [2. Photopolymerization initiator]
In the present specification, the photopolymerization initiator absorbs active energy rays and initiates a photopolymerization reaction (chain polymerization reaction). Examples of the photopolymerization initiator include acylphosphine oxide compounds, alkylphenone compounds, and thioxanthone compounds.
　アシルホスフィンオキサイド系化合物としては、たとえば、２，４，６－トリメチルベンゾイル－ジフェニル－フォスフィンオキシド、およびビス（２，４，６－トリメチルベンゾイル）－フェニルホスフィンオキシドが挙げられる。アシルホスフィンオキシド系化合物の市販品としては、たとえば、ＢＡＳＦ社製「ＩＲＧＡＣＵＲＥ（登録商標）ＴＰＯ」および「ＩＲＧＡＣＵＲＥ（登録商標）８１９」が挙げられる。 Examples of the acylphosphine oxide compounds include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide. Examples of commercially available acylphosphine oxide compounds include “IRGACURE (registered trademark) TPO” and “IRGACURE (registered trademark) 819” manufactured by BASF.
　アルキルフェノン系化合物としては、たとえば、２，２－ジメトキシ－１，２－ジフェニルエタン－１－オン、および２－メチル－１［４－（メチルチオ）フェニル］－２－モルフォリノプロパン－１－オンが挙げられる。アルキルフェノン系化合物の市販品としては、ＢＡＳＦ社製「ＩＲＧＡＣＵＲＥ（登録商標）６５１」、および「ＩＲＧＡＣＵＲＥ（登録商標）９０７」が挙げられる。 Examples of alkylphenone compounds include 2,2-dimethoxy-1,2-diphenylethane-1-one and 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one. Is mentioned. Examples of commercially available alkylphenone compounds include “IRGACURE (registered trademark) 651” and “IRGACURE (registered trademark) 907” manufactured by BASF.
　チオキサントン系化合物としては、たとえば、チオキサントン、２，４－ジメチルチオキサントン、２－クロロチオキサントン、２－エチルチオキサントン、および１－クロロ－４－プロポキシチオキサントンが挙げられる。 Examples of the thioxanthone compound include thioxanthone, 2,4-dimethylthioxanthone, 2-chlorothioxanthone, 2-ethylthioxanthone, and 1-chloro-4-propoxythioxanthone.
　光重合開始剤の含有量は、光重合反応を効率よく進行させる観点から、インク組成物１００質量部に対して５質量部以上２５質量部以下であることが好ましく、１０質量部以上２０質量部以下であることがより好ましい。 The content of the photopolymerization initiator is preferably 5 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the ink composition from the viewpoint of efficiently proceeding the photopolymerization reaction. The following is more preferable.
［３．重合性化合物］
　本明細書において、重合性化合物は、重合反応により重合体を形成し得る化合物である。重合性化合物は、一般式（Ｉ）で表されるビニルエーテル基含有（メタ）アクリル酸エステル類と、アクリルアミド系モノマーおよび単官能（メタ）アクリルモノマーからなる群から選択される少なくとも１種の単官能モノマーと、多官能（メタ）アクリルモノマーとを含む。単官能（メタ）アクリルモノマーの重合体のガラス転移温度が３０℃以上である。多官能（メタ）アクリルモノマーの重合体のガラス転移温度が３０℃以上である。
　また、重合性化合物の含有率は、全インク組成物において６０～８５質量％であることが好ましい。 [3. Polymerizable compound]
In the present specification, a polymerizable compound is a compound that can form a polymer by a polymerization reaction. The polymerizable compound is at least one monofunctional selected from the group consisting of vinyl ether group-containing (meth) acrylic acid esters represented by the general formula (I), acrylamide monomers and monofunctional (meth) acrylic monomers. A monomer and a polyfunctional (meth) acrylic monomer. The glass transition temperature of the polymer of a monofunctional (meth) acryl monomer is 30 ° C. or higher. The glass transition temperature of the polymer of a polyfunctional (meth) acryl monomer is 30 ° C. or higher.
The content of the polymerizable compound is preferably 60 to 85% by mass in the total ink composition.
（３－１．ビニルエーテル基含有（メタ）アクリル酸エステル類）
　ビニルエーテル基含有（メタ）アクリル酸エステル類は、一般式（Ｉ）：
　　ＣＨ２＝ＣＲ１－ＣＯＯＲ２－Ｏ－ＣＨ＝ＣＨ－Ｒ３・・・（Ｉ）
（前記一般式（Ｉ）中、Ｒ１は水素原子またはメチル基を表し、Ｒ２は炭素原子数２以上２０以下の２価の有機残基を表し、Ｒ３は水素原子または炭素原子数１以上１１以下の１価の有機残基を表す）で表される。インク組成物がビニルエーテル基含有（メタ）アクリル酸エステル類を含むと、インク組成物の粘度を１０．５ｍＰａ・ｓ以下とし、後述する一次皮膚刺激性インデックス２以下とすることができる。以下、一般式（Ｉ）で表されるビニルエーテル基含有（メタ）アクリル酸エステル類を（メタ）アクリル酸エステル類（Ｉ）と記載することがある。 (3-1. (Meth) acrylic acid esters containing vinyl ether groups)
Vinyl ether group-containing (meth) acrylic acid esters are represented by the general formula (I):
CH 2 = CR 1 —COOR 2 —O—CH═CH—R 3 (I)
(In the general formula (I), R 1 represents a hydrogen atom or a methyl group, R 2 represents a divalent organic residue having 2 to 20 carbon atoms, and R 3 represents a hydrogen atom or 1 carbon atom. Represents a monovalent organic residue of 11 or less. When the ink composition contains a vinyl ether group-containing (meth) acrylic acid ester, the viscosity of the ink composition can be set to 10.5 mPa · s or less, and the primary skin irritation index 2 described below can be set. Hereinafter, the vinyl ether group-containing (meth) acrylic acid ester represented by the general formula (I) may be referred to as (meth) acrylic acid ester (I).
　炭素原子数２以上２０以下の２価の有機残基としては、たとえば、炭素原子数２以上２０以下のアルキレン基、炭素原子数３以上２０以下のシクロアルキレン基、および炭素原子数６以上１０以下の２価の芳香族基が挙げられる。炭素原子数２以上２０以下の２価の有機残基は置換されていてもよい。 Examples of the divalent organic residue having 2 to 20 carbon atoms include, for example, an alkylene group having 2 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, and 6 to 10 carbon atoms. The bivalent aromatic group of these is mentioned. A divalent organic residue having 2 to 20 carbon atoms may be substituted.
　炭素原子数２以上２０以下のアルキレン基は、直鎖状または分岐鎖状で非置換である。炭素原子数２以上２０以下のアルキル基としては、たとえば、エチレン基、プロピレン基、ブチレン基、ペンチレン基、ヘキシレン基、へプチレン基、オクチレン基、ノニレン基、デシレン基、ウンデシレン基、およびヘキサデシレン基が挙げられる。炭素原子数２以上２０以下のアルキレン基は、炭素原子数２以上９以下のアルキレン基が好ましく、炭素原子数１以上８以下のオキソアルキレン基、酸素原子２個以上４個以下のいずれかで置換された炭素原子数９以上１５以下のアルキレン基および炭素原子数２以上６以下のアルキレン基がより好ましい。 An alkylene group having 2 to 20 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 2 to 20 carbon atoms include ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, and hexadecylene group. Can be mentioned. The alkylene group having 2 to 20 carbon atoms is preferably an alkylene group having 2 to 9 carbon atoms, substituted with an oxoalkylene group having 1 to 8 carbon atoms or any one having 2 to 4 oxygen atoms. The alkylene group having 9 to 15 carbon atoms and the alkylene group having 2 to 6 carbon atoms are more preferable.
　炭素原子数２以上９以下のアルキレン基は、直鎖状または分岐鎖状で非置換である。炭素原子数２以上９以下のアルキル基としては、たとえば、エチレン基、プロピレン基、ブチレン基、ペンチレン基、ヘキシレン基、へプチレン基、オクチレン基、およびノニレン基が挙げられる。 An alkylene group having 2 to 9 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 2 to 9 carbon atoms include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, and a nonylene group.
　炭素原子数１以上８以下のオキソアルキレン基は、直鎖状または分岐状で非置換である。炭素原子数１以上８以下のオキソアルキレン基は、炭素原子数２以上９以下のアルキレン基における１つの－ＣＨ２－が－Ｏ－に置換された置換基である。 An oxoalkylene group having 1 to 8 carbon atoms is linear or branched and unsubstituted. The oxoalkylene group having 1 to 8 carbon atoms is a substituent in which one —CH 2 — in the alkylene group having 2 to 9 carbon atoms is substituted with —O—.
　炭素原子数９以上１５以下のアルキレン基は、直鎖状または分岐鎖状で非置換である。炭素原子数９以上１５以下のアルキレン基としては、たとえば、ノニレン基、デシレン基、ウンデシレン基、ドデシレン基、トリドデシレン基、テトラデシレン基、テトラデシレン基、およびペンタデシレン基が挙げられる。 An alkylene group having 9 to 15 carbon atoms is linear or branched and unsubstituted. Examples of the alkylene group having 9 to 15 carbon atoms include a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tridodecylene group, a tetradecylene group, a tetradecylene group, and a pentadecylene group.
　炭素原子数２以上６以下のアルキレン基は、直鎖状または分岐鎖状で非置換である。炭素原子数２以上６以下のアルキル基としては、たとえば、エチレン基、プロピレン基、ブチレン基、ペンチレン基、およびヘキシレン基が挙げられる。 An alkylene group having 2 to 6 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 2 to 6 carbon atoms include an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group.
　炭素原子数３以上２０以下のシクロアルキレン基は、環状で非置換である。炭素原子数３以上２０以下のシクロアルキレン基としては、たとえば、シクロプロピレン基、シクロブチレン基、シクロペンチレン基、シクロヘキシレン基、シクロへプチレン基、シクロオクチレン基、シクロノニレン基、シクロデシレン基、シクロウンデシレン基、およびシクロヘキサデシレン基が挙げられる。炭素原子数３以上２０以下のシクロアルキレン基は、複数の炭素原子数１以上３以下のアルキル基で置換されていてもよい炭素原子数３以上２０以下のシクロアルキレン基であってもよい。炭素原子数１以上３以下のアルキル基は、直鎖状または分枝鎖状で非置換である。炭素原子数１以上３以下のアルキル基としては、例えば、メチル基、エチル基、プロピル基、およびイソプロピル基が挙げられる。 The cycloalkylene group having 3 to 20 carbon atoms is cyclic and unsubstituted. Examples of the cycloalkylene group having 3 to 20 carbon atoms include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, and a cyclohexane group. Examples include an undecylene group and a cyclohexadecylene group. The cycloalkylene group having 3 to 20 carbon atoms may be a cycloalkylene group having 3 to 20 carbon atoms which may be substituted with a plurality of alkyl groups having 1 to 3 carbon atoms. The alkyl group having 1 to 3 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, a propyl group, and an isopropyl group.
　炭素原子数６以上１０以下の２価の芳香族基は、環状で非置換である。炭素原子数６以上１０以下の２価の芳香族基としては、たとえば、フェニレン基、およびナフチリレン基が挙げられる。炭素原子数６以上１０以下の２価の芳香族基は、複数の炭素原子数１以上３以下のアルキル基で置換されていてもよい炭素原子数６以上１０以下の２価の芳香族基であってもよい。 The divalent aromatic group having 6 to 10 carbon atoms is cyclic and unsubstituted. Examples of the divalent aromatic group having 6 to 10 carbon atoms include a phenylene group and a naphthylylene group. The divalent aromatic group having 6 to 10 carbon atoms is a divalent aromatic group having 6 to 10 carbon atoms which may be substituted with a plurality of alkyl groups having 1 to 3 carbon atoms. There may be.
　炭素原子数１以上１１以下の１価の有機残基としては、たとえば、炭素原子数１以上１０以下のアルキル基、炭素原子数３以上１０以下のシクロアルキル基および炭素原子数６以上１０以下の１価の芳香族基が挙げられる。 Examples of the monovalent organic residue having 1 to 11 carbon atoms include, for example, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and 6 to 10 carbon atoms. A monovalent aromatic group is mentioned.
　炭素原子数１以上１０以下のアルキル基は、直鎖状または分岐鎖状で非置換である。炭素原子数１以上１０以下のアルキル基としては、たとえば、メチル基、エチル基、プロピル基、イソプロピル基、ｎ－ブチル基、ｓｅｃ－ブチル基、ｔｅｒｔ－ブチル基、ペンチル基、イソペンチル基、ネオペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、およびデシル基が挙げられる。炭素原子数１以上１０以下のアルキル基は、炭素原子数１以上３以下のアルキル基が好ましく、フェニル基で置換されていてもよい炭素原子数１以上３以下のアルキル基がより好ましく、メチル基、エチル基、およびベンジル基がさらに好ましい。置換されていてもよい炭素原子数６以上１０以下の１価の芳香族基は、フェニル基が好ましい。炭素原子数１以上３以下のアルキル基は、炭素原子数３以上２０以下のシクロアルキレン基中の炭素原子数１以上３以下のアルキル基と同義である。 An alkyl group having 1 to 10 carbon atoms is linear or branched and unsubstituted. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, and a neopentyl group. Hexyl group, heptyl group, octyl group, nonyl group, and decyl group. The alkyl group having 1 to 10 carbon atoms is preferably an alkyl group having 1 to 3 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms which may be substituted with a phenyl group, and a methyl group. More preferred are an ethyl group and a benzyl group. The monovalent aromatic group having 6 to 10 carbon atoms which may be substituted is preferably a phenyl group. An alkyl group having 1 to 3 carbon atoms is synonymous with an alkyl group having 1 to 3 carbon atoms in a cycloalkylene group having 3 to 20 carbon atoms.
　炭素原子数３以上１０以下のシクロアルキル基は、環状で非置換である。炭素原子数３以上１０以下のシクロアルキル基としては、たとえば、シクロペンタン基、シクロブチル基、シクロペンチル基、シクロヘキシル基、シクロヘプチル基、およびシクロオクチル基が挙げられる。 A cycloalkyl group having 3 to 10 carbon atoms is cyclic and unsubstituted. Examples of the cycloalkyl group having 3 to 10 carbon atoms include a cyclopentane group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.
　炭素原子数６以上１０以下の１価の芳香族基は、環状で非置換である。炭素原子数６以上１０以下の１価値の芳香族基としては、たとえば、フェニル基、およびナフチル基が挙げられる。 The monovalent aromatic group having 6 to 10 carbon atoms is cyclic and unsubstituted. Examples of the 1-value aromatic group having 6 to 10 carbon atoms include a phenyl group and a naphthyl group.
　（メタ）アクリル酸エステル類（Ｉ）としては、たとえば、（メタ）アクリル酸ビニロキシアルキル、（メタ）アクリル酸ビニロキシシクロアルキル、（メタ）アクリル酸アルキルビニロキシアルキル、（メタ）アクリル酸ビニロキシアルキルシクロアルキルアルキル、（メタ）アクリル酸ビニロキシアルキルアリールアルキル、（メタ）アクリル酸ビニロキシアルコキシアルキル、（メタ）アクリル酸ビニロキシアルコキシアルコキシアルキル、および（メタ）アクリル酸ビニロキシアルコキシアルコキシアルコキシアルキルが挙げられる。これらの（メタ）アクリル酸エステル類（Ｉ）は、１種を単独で用いてもよく、２種以上を組み合わせて用いてもよい。 Examples of (meth) acrylic acid esters (I) include vinyloxyalkyl (meth) acrylate, vinyloxycycloalkyl (meth) acrylate, alkylvinyloxyalkyl (meth) acrylate, and vinyl (meth) acrylate. Loxyalkylcycloalkylalkyl, vinyloxyalkylalkylalkyl (meth) acrylate, vinyloxyalkoxyalkyl (meth) acrylate, vinyloxyalkoxyalkoxyalkyl (meth) acrylate, and vinyloxyalkoxyalkoxyalkoxyalkyl (meth) acrylate Is mentioned. These (meth) acrylic acid esters (I) may be used individually by 1 type, and may be used in combination of 2 or more type.
　（メタ）アクリル酸ビニロキシアルキルとしては、たとえば、（メタ）アクリル酸２－ビニロキシエチル、（メタ）アクリル酸２－ビニロキシプロピル、（メタ）アクリル酸４－ビニロキシブチル、および（メタ）アクリル酸２－ビニロキシブチルが挙げられる。 Examples of the vinyloxyalkyl (meth) acrylate include 2-vinyloxyethyl (meth) acrylate, 2-vinyloxypropyl (meth) acrylate, 4-vinyloxybutyl (meth) acrylate, and 2-methacrylic acid 2- Vinyloxybutyl is mentioned.
　（メタ）アクリル酸ビニロキシシクロアルキルとしては、たとえば、（メタ）アクリル酸ビニロキシシクロヘキシルが挙げられる。 Examples of vinyloxycycloalkyl (meth) acrylate include vinyloxycyclohexyl (meth) acrylate.
　（メタ）アクリル酸アルキルビニロキシアルキルとしては、たとえば、（メタ）アクリル酸２－メチル－３－ビニロキシプロピル、および（メタ）アクリル酸１－メチル－２－ビニロキシプロピルが挙げられる。 Examples of the alkylvinyloxyalkyl (meth) acrylate include 2-methyl-3-vinyloxypropyl (meth) acrylate and 1-methyl-2-vinyloxypropyl (meth) acrylate.
　（メタ）アクリル酸ビニロキシアルキルシクロアルキルアルキルとしては、たとえば、（メタ）アクリル酸３－ビニロキシメチルシクロヘキシルメチルが挙げられる。 Examples of (meth) acrylic acid vinyloxyalkylcycloalkylalkyl include, for example, (meth) acrylic acid 3-vinyloxymethylcyclohexylmethyl.
　（メタ）アクリル酸ビニロキシアルキルアリールアルキルとしては、たとえば、（メタ）アクリル酸ｐ－ビニロキシメチルフェニルメチルが挙げられる。 Examples of (meth) acrylic acid vinyloxyalkylarylalkyl include p-vinyloxymethylphenylmethyl (meth) acrylate.
　（メタ）アクリル酸ビニロキシアルコキシアルキルとしては、たとえば、アクリル酸２－（２－ビニロキシエトキシ）エチル（ＶＥＥＡ）、メタクリル酸２－（２－ビニロキシエトキシ）エチル（ＶＥＥＭ）、（メタ）アクリル酸２－（ビニロキシイソプロポキシ）プロピル、および（メタ）アクリル酸２－（ビニロキシイソプロポキシ）イソプロピルが挙げられる。 Examples of (meth) acrylic acid vinyloxyalkoxyalkyl include 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA), 2- (2-vinyloxyethoxy) ethyl methacrylate (VEEM), and (meth) acrylic. Examples include 2- (vinyloxyisopropoxy) propyl 2-acid and 2- (vinyloxyisopropoxy) isopropyl (meth) acrylate.
（メタ）アクリル酸ビニロキシアルコキシアルコキシアルキルとしては、たとえば、（メタ）アクリル酸ビニロキシエトキシエトキシエチルが挙げられる。 Examples of (meth) acrylic acid vinyloxyalkoxyalkoxyalkyl include, for example, (meth) acrylic acid vinyloxyethoxyethoxyethyl.
　（メタ）アクリル酸ビニロキシアルコキシアルコキシアルコキシアルキルとしては、たとえば、（メタ）アクリル酸ビニロキシエトキシエトキシエトキシエチルが挙げられる。 (Vinyloxyalkoxyalkoxyalkoxyalkyl (meth) acrylate includes, for example, vinyloxyethoxyethoxyethoxyethyl (meth) acrylate).
　これら（メタ）アクリル酸エステル類（Ｉ）のうち、低粘度で、臭気が低く皮膚への刺激を抑えることができ、引火点が高く、かつ、反応性及び硬化性に優れ、硬化により形成される塗膜の密着性が優れるため、（メタ）アクリル酸２－（２－ビニロキシエトキシ）エチルが好ましい。 Among these (meth) acrylic acid esters (I), it has low viscosity, low odor, can suppress irritation to the skin, has high flash point, is excellent in reactivity and curability, and is formed by curing. (Meth) acrylic acid 2- (2-vinyloxyethoxy) ethyl is preferred because of excellent adhesion of the coating film.
　（メタ）アクリル酸エステル類（Ｉ）の含有率は、インクを低粘度化させることができ、反応性、塗膜強度及び密着性を向上させる観点から、インク組成物において２０質量％以上６０質量％以下であることが好ましく、２０質量％以上５０質量％以下であることがより好ましく、３０質量％以上５０質量％以下であることがさらに好ましく、３５質量％以上５０質量％以下であることが特に好ましく、３５質量％以上４５質量％以下であることが非常に特に好ましい。 The content of the (meth) acrylic acid esters (I) can reduce the viscosity of the ink, and from the viewpoint of improving the reactivity, the coating film strength, and the adhesion, is 20% by mass or more and 60% by mass in the ink composition. % Or less, more preferably 20% by mass or more and 50% by mass or less, further preferably 30% by mass or more and 50% by mass or less, and more preferably 35% by mass or more and 50% by mass or less. Particularly preferred is 35% by mass or more and 45% by mass or less.
（３－２．単官能モノマー）
　本明細書において、単官能モノマーは、１分子中に重合性の部分（たとえば、エチレン性二重結合）を１つ有する。単官能モノマーは、アクリルアミド系モノマーおよび単官能（メタ）アクリルモノマーからなる群から選択される少なくとも１種である。単官能モノマーの含有率は、インク組成物において１質量％以上９質量％以下である。単官能（メタ）アクリルモノマーの重合体のガラス転移温度Ｔｇが３０℃以上である。単官能モノマーは粘度が比較的低く、かつ単官能（メタ）アクリルモノマーの重合体のガラス転移温度Ｔｇが比較的高い。このため、インク組成物は１質量％以上９質量％以下の含有率で単官能モノマーを含むと、（メタ）アクリル酸エステル類（Ｉ）および多官能（メタ）アクリルモノマーに対して希釈剤として機能し、吐出安定性および安全性に優れかつ強度の優れる塗膜を形成可能な、すなわち３つの性質をバランスよく兼ね備えるインク組成物を提供することができる。単官能モノマーの含有率は、上記３つの性質を更に向上させる観点から、インク組成物において７質量％以上９質量％以下であることが好ましく、５質量％以上９質量％以下であることがより好ましい。 (3-2. Monofunctional monomer)
In the present specification, the monofunctional monomer has one polymerizable moiety (for example, an ethylenic double bond) in one molecule. The monofunctional monomer is at least one selected from the group consisting of acrylamide monomers and monofunctional (meth) acrylic monomers. The content of the monofunctional monomer is 1% by mass or more and 9% by mass or less in the ink composition. The glass transition temperature Tg of the polymer of a monofunctional (meth) acryl monomer is 30 ° C. or higher. The monofunctional monomer has a relatively low viscosity, and the glass transition temperature Tg of the polymer of the monofunctional (meth) acrylic monomer is relatively high. Therefore, when the ink composition contains a monofunctional monomer at a content of 1% by mass or more and 9% by mass or less, it serves as a diluent for the (meth) acrylic acid esters (I) and the polyfunctional (meth) acrylic monomer. It is possible to provide an ink composition that functions, can form a coating film having excellent ejection stability and safety and excellent strength, that is, having three properties in a well-balanced manner. From the viewpoint of further improving the above three properties, the content of the monofunctional monomer is preferably 7% by mass or more and 9% by mass or less in the ink composition, and more preferably 5% by mass or more and 9% by mass or less. preferable.
　一次皮膚刺激性インデックス（Ｐｒｉｍａｒｙ　Ｉｒｒｉｔａｔｉｏｎ　Ｉｎｄｅｘ：ＰＩＩ値）は、皮膚刺激性を示す物性値である。ＰＩＩ値が大きいほど、皮膚への刺激性が強く、取り扱いに注意を要する化合物であることを示す。 The primary skin irritation index (Primary Irritation Index: PII value) is a physical property value indicating skin irritation. The larger the PII value, the stronger the irritation to the skin, indicating that the compound requires careful handling.
（３－２－１．アクリルアミド系モノマー）
　アクリルアミド系モノマーとしては、たとえば、ジメチルアクリルアミド、ジエチルアクリルアミド、２－ヒドロキシエチルアクリルアミド、ジメチルアミノプロピルアクリルアミド、およびアクリロイルモルフォリン（ＡＣＭＯ）が挙げられる。これらのアクリルアミド系モノマーのうち、環状構造（より具体的には、脂環式構造またはヘテロ環式構造等）を有するアクリルアミド系モノマーが好ましく、アクリロイルモルフォリンがより好ましい。 (3-2-1. Acrylamide monomer)
Examples of the acrylamide monomer include dimethylacrylamide, diethylacrylamide, 2-hydroxyethylacrylamide, dimethylaminopropylacrylamide, and acryloylmorpholine (ACMO). Of these acrylamide monomers, acrylamide monomers having a cyclic structure (more specifically, an alicyclic structure or a heterocyclic structure) are preferable, and acryloylmorpholine is more preferable.
（３－２－２．単官能（メタ）アクリルモノマー）
　単官能（メタ）アクリルモノマーとしては、たとえば、鎖状構造または環状構造を有する単官能（メタ）アクリルモノマーが挙げられる。ここで、ここで鎖状構造を有する単官能（メタ）アクリルモノマーは、その分子構造中に環式構造を有さず、直鎖状構造または分岐状構造を有する。環状構造を有する単官能（メタ）アクリルモノマーは、その分子構造中に環状構造を有し、鎖状構造をさらに有してもよい。 (3-2-2. Monofunctional (meth) acrylic monomer)
Examples of the monofunctional (meth) acrylic monomer include a monofunctional (meth) acrylic monomer having a chain structure or a cyclic structure. Here, the monofunctional (meth) acrylic monomer having a chain structure here does not have a cyclic structure in its molecular structure, but has a linear structure or a branched structure. The monofunctional (meth) acrylic monomer having a cyclic structure has a cyclic structure in its molecular structure and may further have a chain structure.
　単官能（メタ）アクリルモノマーは、該単官能（メタ）アクリルモノマーの重合体が３０℃以上のガラス転移温度を有する観点から、環状構造を有することが好ましい。環状構造を有する単官能（メタ）アクリルモノマーとしては、たとえば、単環の脂環式（メタ）アクリレート、複環の脂環式（メタ）アクリレート、およびヘテロ環式（メタ）アクリレートが挙げられる。単環の脂環式（メタ）アクリレートとしては、たとえば、シクロアルキル（メタ）アクリレート（より具体的には、３，３，５－トリメチルシクロヘキシルアクリレート（ＴＭＣＨＡ）等）が挙げられる。複環の脂環式（メタ）アクリレートとしては、たとえば、イソボルニルアクリレート（ＩＢＯＡ）、イソボルニルメタクリレート、ノルボルニル（メタ）アクリレート、アマダンチル（メタ）アクリレート、およびジシクロペンタニル（メタ）アクリレートが挙げられる。ヘテロ環式（メタ）アクリレートとしては、たとえば、環状トリメチロールプロパンホルマールアクリレート（ＣＴＦＡ）が挙げられる。これらの単官能（メタ）アクリルモノマーは１種を単独で用いてもよく、２種以上を組み合わせて用いてもよい。 The monofunctional (meth) acrylic monomer preferably has a cyclic structure from the viewpoint that the polymer of the monofunctional (meth) acrylic monomer has a glass transition temperature of 30 ° C. or higher. Examples of the monofunctional (meth) acrylic monomer having a cyclic structure include monocyclic alicyclic (meth) acrylates, bicyclic alicyclic (meth) acrylates, and heterocyclic (meth) acrylates. Examples of the monocyclic alicyclic (meth) acrylate include cycloalkyl (meth) acrylate (more specifically, 3,3,5-trimethylcyclohexyl acrylate (TMCHA) and the like). Examples of the bicyclic alicyclic (meth) acrylate include isobornyl acrylate (IBOA), isobornyl methacrylate, norbornyl (meth) acrylate, amadantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate. Can be mentioned. Examples of the heterocyclic (meth) acrylate include cyclic trimethylolpropane formal acrylate (CTFA). These monofunctional (meth) acrylic monomers may be used individually by 1 type, and may be used in combination of 2 or more type.
　これらの単官能（メタ）アクリルモノマーのうち、イソボルニルアクリレート（ＩＢＯＡ）、３，３，５－トリメチルシクロヘキシルアクリレート（ＴＭＣＨＡ）、および環状トリメチロールプロパンホルマールアクリレート（ＣＴＦＡ）、およびイソボルニルメタクリレートからなる群から選択される少なくとも１種が好ましく、イソボルニルアクリレート（ＩＢＯＡ）、３，３，５－トリメチルシクロヘキシルアクリレート（ＴＭＣＨＡ）、および環状トリメチロールプロパンホルマールアクリレート（ＣＴＦＡ）からなる群から選択される少なくとも１種がより好ましい。 Among these monofunctional (meth) acrylic monomers, from isobornyl acrylate (IBOA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), and cyclic trimethylolpropane formal acrylate (CTFA), and isobornyl methacrylate At least one selected from the group consisting of isobornyl acrylate (IBOA), 3,3,5-trimethylcyclohexyl acrylate (TMCHA), and cyclic trimethylolpropane formal acrylate (CTFA) At least one is more preferable.
　単官能（メタ）アクリルモノマーの重合体のガラス転移温度Ｔｇは、塗膜強度を向上させる観点から、３０℃以上である。単官能（メタ）アクリルモノマーのガラス転移温度は、優れた塗膜強度を維持しつつ、吐出安定性および安全性を向上させる観点から、３０℃以上９０℃以下であることが好ましく、４０℃以上９０℃以下であることがより好ましい。なお、本明細書において、単官能（メタ）アクリルモノマーの重合体とは、単官能（メタ）アクリルモノマーが単独で重合した重合体である。すなわち、該重合体が実質的に１種の単官能（メタ）アクリルモノマー由来の繰返し単位からなることを意味する。重合体が実質的に１種の単官能（メタ）アクリルモノマー由来の繰返し単位からなるとは、重合体を構成する全繰返し単位に対して１種の単官能（メタ）アクリルモノマー由来の繰返し単位が９９モル％以上であることを意味する。 The glass transition temperature Tg of the polymer of monofunctional (meth) acrylic monomer is 30 ° C. or higher from the viewpoint of improving the coating film strength. The glass transition temperature of the monofunctional (meth) acrylic monomer is preferably 30 ° C. or more and 90 ° C. or less, and 40 ° C. or more, from the viewpoint of improving ejection stability and safety while maintaining excellent coating strength. More preferably, it is 90 ° C. or lower. In the present specification, the polymer of a monofunctional (meth) acrylic monomer is a polymer obtained by polymerizing a monofunctional (meth) acrylic monomer alone. That is, it means that the polymer consists essentially of a repeating unit derived from one monofunctional (meth) acrylic monomer. The polymer substantially consists of a repeating unit derived from one monofunctional (meth) acrylic monomer means that the repeating unit derived from one monofunctional (meth) acrylic monomer is composed of all repeating units constituting the polymer. It means 99 mol% or more.
（３－３．多官能（メタ）アクリルモノマー）
　本明細書において、多官能（メタ）アクリルモノマーは、１分子中に重合性の部分（たとえば、エチレン性二重結合）を２以上有する。多官能（メタ）アクリルモノマーとしては、二官能（メタ）アクリルモノマー、三官能（メタ）アクリルモノマー、四官能（メタ）アクリルモノマー、および五官能（メタ）アクリルモノマーが挙げられる。多官能（メタ）アクリルモノマーは、鎖状構造または脂環式構造を有してもよい。ここで鎖状構造を有する多官能（メタ）アクリルモノマーは、その分子構造中に環式構造を有さず、直鎖状構造または分岐状構造を有する。脂環式構造を有する多官能（メタ）アクリルモノマーは、その分子構造中に脂環式構造を有し、鎖状構造をさらに有してもよい。 (3-3. Multifunctional (meth) acrylic monomer)
In the present specification, the polyfunctional (meth) acrylic monomer has two or more polymerizable moieties (for example, ethylenic double bonds) in one molecule. Examples of polyfunctional (meth) acrylic monomers include bifunctional (meth) acrylic monomers, trifunctional (meth) acrylic monomers, tetrafunctional (meth) acrylic monomers, and pentafunctional (meth) acrylic monomers. The polyfunctional (meth) acrylic monomer may have a chain structure or an alicyclic structure. Here, the polyfunctional (meth) acrylic monomer having a chain structure does not have a cyclic structure in its molecular structure, but has a linear structure or a branched structure. The polyfunctional (meth) acrylic monomer having an alicyclic structure has an alicyclic structure in its molecular structure and may further have a chain structure.
　多官能（メタ）アクリルモノマーは、該多官能（メタ）アクリルモノマーの重合体が３０℃以上のガラス転移温度を有し、かつインク組成物の安全性を向上させる観点から、二官能（メタ）アクリルモノマーが好ましく、鎖状構造を有する二官能（メタ）アクリルモノマーと、脂環式構造を有する二官能（メタ）アクリルモノマーとを含むことがより好ましく、鎖状構造を有する二官能（メタ）アクリルモノマーのみを含むことがさらに好ましい。 The polyfunctional (meth) acrylic monomer is a bifunctional (meth) from the viewpoint that the polymer of the polyfunctional (meth) acrylic monomer has a glass transition temperature of 30 ° C. or more and improves the safety of the ink composition. An acrylic monomer is preferable, and it is more preferable to include a bifunctional (meth) acrylic monomer having a chain structure and a bifunctional (meth) acrylic monomer having an alicyclic structure, and a bifunctional (meth) having a chain structure. More preferably, it contains only acrylic monomers.
　鎖状構造を有する二官能（メタ）アクリルモノマーとしては、たとえば、アルカンジオールジアクリレート（より具体的には、メチル－１，５－ペンタンジオールジアクリレート（ＭＰＤＤＡ）、１，９－ノナンジオールジアクリレート（１，９ＮＤ－Ａ）、および１，１０－デカンジオールジアクリレート（ＤＤＤＡ）等）、ポリアルキレングリコールジアクリレート（より具体的には、ジプロピレングリコールジアクリレート（ＤＰＧＤＡ）、およびトリプロピレングリコールジアクリレート（ＴＰＧＤＡ）等）および他のジアクリレート（より具体的には、ネオペンチルグリコールヒドロキシピバリン酸エステルジアクリレート（ＨＰＮＤＡ）、およびネオペンチルグリコールプロピレンオキシドジアクリレート（ＮＰＧＰＯＤＡ）等）が挙げられる。これら鎖状構造を有する多官能（メタ）アクリルモノマーは、１種を単独で用いてもよく、２種以上を組み合わせて用いてもよい。 Examples of the bifunctional (meth) acrylic monomer having a chain structure include alkanediol diacrylate (more specifically, methyl-1,5-pentanediol diacrylate (MPDDA), 1,9-nonanediol diacrylate). (1,9ND-A), and 1,10-decandiol diacrylate (DDDA), etc.), polyalkylene glycol diacrylate (more specifically, dipropylene glycol diacrylate (DPGDA), and tripropylene glycol diacrylate) (TPGDA) etc.) and other diacrylates (more specifically, neopentyl glycol hydroxypivalate ester diacrylate (HPNDA), and neopentyl glycol propylene oxide diacrylate (NPPGODA) ), And the like. These polyfunctional (meth) acrylic monomers having a chain structure may be used singly or in combination of two or more.
　環状構造を有する二官能（メタ）アクリルモノマーとしては、たとえば、ジシクロペンタニルジアクリレート（ＤＣＰＤＡ）が挙げられる。 Examples of the bifunctional (meth) acrylic monomer having a cyclic structure include dicyclopentanyl diacrylate (DCPDA).
　二官能以外の多官能（メタ）アクリルモノマーとしては、たとえば、プロポキシ化トリメチロールプロパントリ（メタ）アクリレート、グリセリンプロポキシトリ（メタ）アクリレート若しくはペンタエリスリトールトリ（メタ）アクリレートのような三官能（メタ）アクリルモノマー、ペンタエリスリトールテトラ（メタ）アクリレートのような四官能（メタ）アクリルモノマー、およびジペンタエリストリエールヒドロキシペンタ（メタ）アクリレートのような五官能（メタ）アクリルモノマーが挙げられる。 Examples of polyfunctional (meth) acrylic monomers other than bifunctional are trifunctional (meth) such as propoxylated trimethylolpropane tri (meth) acrylate, glycerin propoxytri (meth) acrylate or pentaerythritol tri (meth) acrylate. Examples include acrylic monomers, tetrafunctional (meth) acrylic monomers such as pentaerythritol tetra (meth) acrylate, and pentafunctional (meth) acrylic monomers such as dipentaerythritol hydroxypenta (meth) acrylate.
　これらの多官能（メタ）アクリルモノマーのうち、ジシクロペンタニルジアクリレート（ＤＣＰＤＡ）、メチル－１，５－ペンタンジオールジアクリレート（ＭＰＤＤＡ）、ジプロピレングリコールジアクリレート（ＤＰＧＤＡ）、ネオペンチルグリコールヒドロキシピバリン酸エステルジアクリレート（ＨＰＮＤＡ）、１，１０－デカンジオールジアクリレート（ＤＤＤＡ）、トリプロピレングリコールジアクリレート（ＴＰＧＤＡ）、ネオペンチルグリコールプロピレンオキシドジアクリレート（ＮＰＧＰＯＤＡ）および１，９－ノナンジオールジアクリレート（１，９ＮＤ－Ａ）が好ましく、ジプロピレングリコールジアクリレート（ＤＰＧＤＡ）、ネオペンチルグリコールヒドロキシピバリン酸エステルジアクリレート（ＨＰＮＤＡ）、１，９－ノナンジオールジアクリレート（１，９ＮＤ－Ａ）、トリプロピレングリコールジアクリレート（ＴＰＧＤＡ）、およびネオペンチルグリコールプロピレンオキシドジアクリレート（ＮＰＧＰＯＤＡ）からなる群から選択される少なくとも１種がより好ましい。 Among these polyfunctional (meth) acrylic monomers, dicyclopentanyl diacrylate (DCPDA), methyl-1,5-pentanediol diacrylate (MPDDA), dipropylene glycol diacrylate (DPGDA), neopentyl glycol hydroxypivalin Acid ester diacrylate (HPNDA), 1,10-decanediol diacrylate (DDDA), tripropylene glycol diacrylate (TPGDA), neopentyl glycol propylene oxide diacrylate (NPPGODA) and 1,9-nonanediol diacrylate (1 9ND-A), dipropylene glycol diacrylate (DPGDA), neopentyl glycol hydroxypivalate diacrylate (HPND) ), 1,9-nonanediol diacrylate (1,9ND-A), tripropylene glycol diacrylate (TPGDA), and neopentyl glycol propylene oxide diacrylate (NPPGODA). preferable.
　多官能（メタ）アクリルモノマーの重合体のガラス転移温度Ｔｇは、塗膜強度を向上させる観点から、３０℃以上である。多官能（メタ）アクリルモノマーのガラス転移温度Ｔｇは、優れた塗膜強度を維持しつつ、吐出安定性および安全性を向上させる観点から、３０℃以上２００℃以下であることが好ましく、３０℃以上１５０℃以下であることがより好ましい。なお、本明細書において、多官能（メタ）アクリルモノマーの重合体とは、多官能（メタ）アクリルモノマーが単独で重合した重合体である。すなわち、該重合体が実質的に１種の多官能（メタ）アクリルモノマー由来の繰返し単位からなることを意味する。重合体が実質的に１種の多官能（メタ）アクリルモノマー由来の繰返し単位からなるとは、重合体を構成する全繰返し単位に対して１種の多官能（メタ）アクリルモノマー由来の繰返し単位が９９モル％以上であることを意味する。 The glass transition temperature Tg of the polymer of the polyfunctional (meth) acrylic monomer is 30 ° C. or higher from the viewpoint of improving the coating film strength. The glass transition temperature Tg of the polyfunctional (meth) acrylic monomer is preferably 30 ° C. or higher and 200 ° C. or lower from the viewpoint of improving ejection stability and safety while maintaining excellent coating strength. The temperature is more preferably 150 ° C. or lower. In the present specification, the polymer of the polyfunctional (meth) acrylic monomer is a polymer obtained by polymerizing the polyfunctional (meth) acrylic monomer alone. That is, it means that the polymer consists essentially of repeating units derived from one kind of polyfunctional (meth) acrylic monomer. The polymer substantially consists of a repeating unit derived from one kind of polyfunctional (meth) acrylic monomer means that the repeating unit derived from one kind of polyfunctional (meth) acrylic monomer is composed of all repeating units constituting the polymer. It means 99 mol% or more.
　多官能（メタ）アクリルモノマーの含有率は、インク組成物の吐出安定性および安全性を向上させ、かつ塗膜強度を向上させる観点から、インク組成物において５質量％以上５０質量％であり、１０質量％以上４０質量％以下であることが好ましい。多官能（メタ）アクリルモノマーの含有率は、インク組成物が顔料としてホワイト色の顔料を含む場合、５質量％以上２０質量％以下であることが好ましく、１０質量％以上１５質量％以下であることがより好ましい。また、多官能（メタ）アクリルモノマーの含有率は、インク組成物が顔料としてホワイト色以外の顔料（より具体的には、シアン色、マゼンタ色、イエロー色、又はブラック色の顔料等）を含む場合、２５質量％以上５０質量％以下であることが好ましく、３０質量％以上４５質量％以下であることがより好ましく、３０質量％以上４０質量％以下であることが好ましい。
The content of the polyfunctional (meth) acrylic monomer is 5% by mass or more and 50% by mass in the ink composition from the viewpoint of improving the ejection stability and safety of the ink composition and improving the coating film strength. It is preferable that they are 10 mass% or more and 40 mass% or less. The content of the polyfunctional (meth) acrylic monomer is preferably 5% by mass or more and 20% by mass or less, preferably 10% by mass or more and 15% by mass or less when the ink composition contains a white pigment as a pigment. It is more preferable. The content of the polyfunctional (meth) acrylic monomer is such that the ink composition includes a pigment other than white as a pigment (more specifically, a cyan, magenta, yellow, or black pigment). In this case, it is preferably 25% by mass or more and 50% by mass or less, more preferably 30% by mass or more and 45% by mass or less, and more preferably 30% by mass or more and 40% by mass or less.
［４．他の成分］
　インク組成物は、重合性化合物および光重合開始剤の他に、必要に応じて任意の成分をさらに含んでもよい。任意の成分としては、たとえば、界面活性剤（表面張力調整剤）、着色材、重合禁止剤、分散剤、有機溶剤、定着性樹脂、レベリング剤、消泡剤、酸化防止剤、ｐＨ調整剤、電荷付与剤、殺菌剤、防腐剤、防臭剤、電荷調整剤、湿潤剤、および紫外線吸収剤が挙げられる。これらの任意の成分は、１種を単独で使用してもよく、２種以上を組み合わせて使用してもよい。 [4. Other ingredients]
The ink composition may further contain an optional component as necessary in addition to the polymerizable compound and the photopolymerization initiator. As optional components, for example, surfactant (surface tension adjusting agent), coloring material, polymerization inhibitor, dispersant, organic solvent, fixing resin, leveling agent, antifoaming agent, antioxidant, pH adjusting agent, Examples include charge imparting agents, bactericides, antiseptics, deodorants, charge control agents, wetting agents, and ultraviolet absorbers. These arbitrary components may be used individually by 1 type, and may be used in combination of 2 or more type.
（４－１．界面活性剤）
　記録媒体および／またはインクジェットヘッドのノズル基板へのインクのぬれ性を調整する目的で、インク組成物は界面活性剤を含んでもよい。界面活性剤としては、たとえば、シリコーン系化合物が挙げられる。シリコーン系化合物としては、たとえば、ジメチルシロキサン構造を有するシリコーン系化合物が好ましく、ポリエーテル変性ポリジメチルシロキサンがより好ましい。界面活性剤の市販品としては、たとえば、ビックケミー社製「ＢＹＫ－３５０、３５２、３５４、３５５、３５８Ｎ、３６１Ｎ、３８１Ｎ、３８１、３９２、ＢＹＫ－３００、３０２、３０６、３０７、３１０、３１５、３２０、３２２、３２３、３２５、３３０、３３１、３３３、３３７、３４０、３４４、３４８、３７０、３７５、３７７、３７８、３５５、３５６、３５７、３９０、ＵＶ３５００、ＵＶ３５１０、およびＵＶ３５７０」、テゴケミー社製「Ｔｅｇｏｒａｄ－２１００、２２００、２２５０、２５００、および２７００」、並びにエボニックデグサ社製「ＴＥＧＯ（登録商標）　Ｇｌｉｄｅ　１００、１１０、１３０、４０３、４０６、４１０、４１１、４１５、４３２、４３５、４４０、４５０、および４８２」等が挙げられるがこれに限定されるものではない。これら界面活性剤は、１種を単独で用いてもよく、２種以上を組み合わせて用いてもよい。界面活性剤は、良好な相溶性を維持する観点から、２種以上を用いることが好ましい。２種以上の界面活性剤を併用することにより、インク組成物を長期間保存した場合でも良好な相溶性を保つためインク組成物が記録媒体上で十分に濡れ広がり、顔料の特徴である広い色再現性を保つことができるからである。 (4-1. Surfactant)
In order to adjust the wettability of the ink to the recording medium and / or the nozzle substrate of the inkjet head, the ink composition may contain a surfactant. Examples of the surfactant include silicone compounds. As the silicone compound, for example, a silicone compound having a dimethylsiloxane structure is preferable, and a polyether-modified polydimethylsiloxane is more preferable. Examples of commercially available surfactants include BYK-350, 352, 354, 355, 358N, 361N, 381N, 381, 392, BYK-300, 302, 306, 307, 310, 315, and 320 manufactured by BYK Chemie. 322, 323, 325, 330, 331, 333, 337, 340, 344, 348, 370, 375, 377, 378, 355, 356, 357, 390, UV3500, UV3510, and UV3570, "Tegorad" manufactured by Tegochemy -2100, 2200, 2250, 2500, and 2700 ”, and“ TEGO® Glide 100, 110, 130, 403, 406, 410, 411, 415, 432, 435, 440, 450, and Evonik Degussa ” 482 "etc. It is but not limited thereto. These surfactants may be used individually by 1 type, and may be used in combination of 2 or more type. From the viewpoint of maintaining good compatibility, it is preferable to use two or more surfactants. By using two or more surfactants in combination, the ink composition can be sufficiently wetted and spread on the recording medium to maintain good compatibility even when the ink composition is stored for a long period of time. This is because reproducibility can be maintained.
　界面活性剤の含有量は、記録媒体に対する本発明のインク組成物の濡れ性を向上させる観点から、インク組成物１００質量部に対して０．０１質量部以上５質量部以下であることが好ましく、０．０５質量部以上３質量部以下であることがより好ましく、０．５質量部以上２質量部以下であることが更に好ましい。 The content of the surfactant is preferably 0.01 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the ink composition from the viewpoint of improving the wettability of the ink composition of the present invention with respect to the recording medium. 0.05 parts by mass or more and 3 parts by mass or less, more preferably 0.5 parts by mass or more and 2 parts by mass or less.
（４－２．重合禁止剤）
　光重合反応の進行を制御する目的で、インク組成物は重合禁止剤を含んでもよい。重合禁止剤としては、たとえば、ヒドロキノン系化合物、カテコール系化合物、およびフェノール系化合物が挙げられる。ヒドロキノン系化合物としては、たとえば、ヒドロキノン、メチルヒドロキノン、ヒドロキノンモノメチルエーテル、ｔｅｒｔ－ブチルヒドロキノン、およびジｔｅｒｔ－ブチルヒドロキノンが挙げられる。カテコール系化合物としては、たとえば、カテコール、メチルカテコール、およびｔｅｒｔ－ブチルカテコールが挙げられる。フェノール系化合物としては、たとえば、フェノール、３，５－ジｔｅｒｔ－ブチル－４－ヒドロキシトルエン（ブチルヒドロキシトルエン（ＢＨＴ））、クレゾール、およびメトキノンが挙げられる。 (4-2. Polymerization inhibitor)
In order to control the progress of the photopolymerization reaction, the ink composition may contain a polymerization inhibitor. Examples of the polymerization inhibitor include hydroquinone compounds, catechol compounds, and phenol compounds. Examples of the hydroquinone compound include hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, tert-butylhydroquinone, and ditert-butylhydroquinone. Examples of the catechol-based compound include catechol, methyl catechol, and tert-butyl catechol. Examples of phenolic compounds include phenol, 3,5-ditert-butyl-4-hydroxytoluene (butylhydroxytoluene (BHT)), cresol, and methoquinone.
　重合禁止剤の含有量は、本発明のインク組成物の保存安定性及びシングルパス方式での硬化性を両立させる観点から、インク組成物１００質量部に対して０．０５質量部以上５質量部以下であることが好ましく、０．２０質量部以上２質量部以下であることが好ましく、０．１質量部以上１質量部以下であることがより好ましい。 The content of the polymerization inhibitor is 0.05 parts by mass or more and 5 parts by mass with respect to 100 parts by mass of the ink composition from the viewpoint of achieving both the storage stability of the ink composition of the present invention and the curability in the single pass method. The content is preferably 0.20 parts by mass or more and 2 parts by mass or less, and more preferably 0.1 parts by mass or more and 1 part by mass or less.
（４－３．着色材）
　着色材としては、たとえば、顔料および染料が挙げられる。形成される画像の耐候性を向上させる観点から、顔料（より具体的には、有機顔料および無機顔料等）が好ましい。 (4-3. Colorant)
Examples of the colorant include pigments and dyes. From the viewpoint of improving the weather resistance of the formed image, a pigment (more specifically, an organic pigment, an inorganic pigment, or the like) is preferable.
　ブラック色の着色材としては、たとえば、カーボンブラックが挙げられる。ブラック色の着色材の市販品としては、たとえば、東海カーボン社製のトーカブラック；三菱化学社製のＨＣＦ、ＭＣＦ、ＲＣＦ、ＬＦＦ、ＳＣＦ；デグサ・ヒュルス社製のカラーブラック、スペシャルブラック、プリンテックス；コロンビア社製のラヴェン；キャボット社製のモナーク、リーガルが挙げられる。 Examples of the black colorant include carbon black. Commercially available black colorants include, for example, Toka Black manufactured by Tokai Carbon; HCF, MCF, RCF, LFF, SCF manufactured by Mitsubishi Chemical; Color Black, Special Black, and Printex manufactured by Degussa Huls Colombia's Raven; Cabot's Monarch and Legal.
　シアン色の着色材としては、たとえば、銅フタロシアニン化合物、アントラキノン化合物、および塩基染料レーキ化合物が挙げられる。シアン色の着色材としては、たとえば、Ｃ．Ｉ．ピグメントブルー（１、７、１５、１５：１、１５：２、１５：３、１５：４、６０、６２、又は６６）が挙げられる。 Examples of cyan colorants include copper phthalocyanine compounds, anthraquinone compounds, and basic dye lake compounds. Examples of cyan colorants include C.I. I. Pigment blue (1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, or 66).
　イエローの着色材としては、たとえば、縮合アゾ化合物、イソインドリノン化合物、アントラキノン化合物、アゾ金属錯体、メチン化合物、又はアリールアミド化合物が挙げられる。イエロー色の着色材としては、たとえば、Ｃ．Ｉ．ピグメントイエロー（１、３、１２、１３、１４、１５、１７、６２、７４、８３、９３、９４、９５、９７、１０９、１１０、１１１、１２０、１２７、１２８、１２９、１３８、１４７、１５１、１５４、１５５、１６８、１７４、１７５、１７６、１８０、１８１、１８５、１９１、１９４、および２１４）が挙げられる。 Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and arylamide compounds. Examples of yellow colorants include C.I. I. Pigment Yellow (1, 3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 138, 147, 151 154, 155, 168, 174, 175, 176, 180, 181, 185, 191, 194, and 214).
　マゼンタ色の着色材としては、たとえば、縮合アゾ化合物、ジケトピロロピロール化合物、アントラキノン化合物、キナクリドン化合物、塩基染料レーキ化合物、ナフトール化合物、ベンズイミダゾロン化合物、チオインジゴ化合物、又はペリレン化合物が挙げられる。マゼンタ色の着色材としては、たとえば、Ｃ．Ｉ．ピグメントレッド（２、３、５、６、７、１９、２３、４８：２、４８：３、４８：４、５７：１、８１：１、１２２、１４４、１４６、１５０、１６６、１６８、１７７、１８４、１８５、２０２、２０６、２２０、２２１、又は２５４）が挙げられる。 Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Examples of the magenta colorant include C.I. I. Pigment Red (2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 168, 177 184, 185, 202, 206, 220, 221 or 254).
　ホワイト色の着色材としては、たとえば、ホワイト色の有機顔料（より具体的には、ピグメントホワイト６，１８，２１等）、ホワイト色の無機顔料（より具体的には、塩基性炭酸鉛、酸化亜鉛、酸化チタン、およびチタン酸ストロンチウム等）が挙げられる。 Examples of white colorants include white organic pigments (more specifically, Pigment White 6, 18, 21 etc.), white inorganic pigments (more specifically, basic lead carbonate, oxidation). Zinc, titanium oxide, strontium titanate, etc.).
　顔料の分散平均粒子径は、インク組成物における顔料の分散性を向上させる観点から、２０～２５０ｎｍであることが好ましく、５０～２３０ｎｍであることがより好ましい。 From the viewpoint of improving the dispersibility of the pigment in the ink composition, the dispersion average particle diameter of the pigment is preferably 20 to 250 nm, and more preferably 50 to 230 nm.
　着色材の含有量は、インク組成物１００質量部に対して０．５質量部以上２５質量部以下であることが好ましく、１．０質量部以上２０質量部以下であることがより好ましく、２．０質量部以上１５質量部以下であることが更に好ましい。 The content of the colorant is preferably from 0.5 parts by weight to 25 parts by weight, more preferably from 1.0 parts by weight to 20 parts by weight, with respect to 100 parts by weight of the ink composition. It is still more preferable that it is 0.0 mass part or more and 15 mass parts or less.
（４－４．分散剤）
　インク組成物中で着色材を分散させる目的で、インク組成物は分散剤（より具体的には、顔料分散体等）を含んでもよい。分散剤としては、たとえば、ポリビニルアルコール、アクリル酸系樹脂、スチレン－アクリル酸系樹脂、および酢酸ビニル系樹脂が挙げられる。アクリル酸系樹脂としては、たとえば、ポリアクリル酸、アクリル酸－アクリロニトリル共重合体、およびアクリル酸－アクリル酸アルキルエステル共重合体が挙げられる。スチレン－アクリル酸系樹脂としては、たとえば、スチレン－アクリル酸共重合体、スチレン－メタクリル酸共重合体、およびスチレン－アクリル酸－アクリル酸アルキルエステル共重合体が挙げられる。酢酸ビニル系樹脂としては、たとえば、酢酸ビニル－エチレン共重合体、および酢酸ビニル－マレイン酸エステル共重合体が挙げられる。 (4-4. Dispersant)
In order to disperse the colorant in the ink composition, the ink composition may contain a dispersant (more specifically, a pigment dispersion or the like). Examples of the dispersant include polyvinyl alcohol, acrylic acid resin, styrene-acrylic acid resin, and vinyl acetate resin. Examples of the acrylic resin include polyacrylic acid, acrylic acid-acrylonitrile copolymer, and acrylic acid-alkyl acrylate copolymer. Examples of the styrene-acrylic acid resin include a styrene-acrylic acid copolymer, a styrene-methacrylic acid copolymer, and a styrene-acrylic acid-acrylic acid alkyl ester copolymer. Examples of the vinyl acetate resin include a vinyl acetate-ethylene copolymer and a vinyl acetate-maleic acid ester copolymer.
　分散剤の含有量は、インク組成物の分散安定性が良好となり、長期経時後も初期と同等の品質を示す観点から、インク組成物１００質量部に対して０．１質量部以上３質量部以下であることが好ましく、０．５質量部以上１．５質量部以下であることがより好ましい。 The content of the dispersing agent is from 0.1 to 3 parts by mass with respect to 100 parts by mass of the ink composition from the viewpoint of improving the dispersion stability of the ink composition and exhibiting the same quality as the initial stage even after long-term aging. Or less, more preferably 0.5 parts by mass or more and 1.5 parts by mass or less.
（４－５．有機溶剤）
　インク組成物は、インク組成物の粘度を調整する目的で、有機溶剤を含んでもよい。インク組成物の乾燥性および形成画像の転写性を向上させる観点から、インク組成物は有機溶剤を実質的に含まないことが好ましい。このようにインク組成物は、希釈する目的で有機溶剤を含む必要がないため、インク組成物を吐出する際に粘度を調整する目的でインク組成物を過度に加熱する必要がない。また、インク組成物は、希釈する目的で有機溶剤を含む必要がないため、インク組成物の保存中又は使用中に、インク組成物中の有機溶剤の揮発に起因するインク組成物の粘度の上昇等が生じにくい。更に、インク組成物が顔料を含む場合であっても、粘度上昇に伴う顔料の沈降が抑制され、良好な分散安定性を有する傾向にある。このように、インク組成物は、吐出安定性を更に向上させる観点からも、有機溶剤を実質的に含まないことが好ましい。有機溶剤の含有量は、インク組成物１００質量部に対して３質量部以下であることが好ましく、１質量部以下であることがより好ましく、０質量部であることが更に好ましい。有機溶剤としては、たとえば、芳香族炭化水素、脂肪族炭化水素、エーテル、およびケトンが挙げられる。 (4-5. Organic solvent)
The ink composition may contain an organic solvent for the purpose of adjusting the viscosity of the ink composition. From the viewpoint of improving the drying property of the ink composition and the transferability of the formed image, the ink composition preferably contains substantially no organic solvent. Thus, since the ink composition does not need to contain an organic solvent for the purpose of dilution, it is not necessary to heat the ink composition excessively for the purpose of adjusting the viscosity when discharging the ink composition. In addition, since the ink composition does not need to contain an organic solvent for the purpose of dilution, the viscosity of the ink composition increases due to the volatilization of the organic solvent in the ink composition during storage or use of the ink composition. Etc. are less likely to occur. Further, even when the ink composition contains a pigment, the precipitation of the pigment accompanying an increase in viscosity is suppressed, and the dispersion tends to have good dispersion stability. Thus, the ink composition preferably does not substantially contain an organic solvent from the viewpoint of further improving ejection stability. The content of the organic solvent is preferably 3 parts by mass or less, more preferably 1 part by mass or less, and still more preferably 0 parts by mass with respect to 100 parts by mass of the ink composition. Examples of the organic solvent include aromatic hydrocarbons, aliphatic hydrocarbons, ethers, and ketones.
［５．一次皮膚刺激性インデックス（ＰＩＩ値）］
　インク組成物のＰＩＩ値は、インク組成物の安全性を向上させる観点から、２未満であることが好ましく、２．００未満であることがより好ましく、１．７０未満であることが更に好ましい。インク組成物のＰＩＩ値の算出方法は、実施例に記載する。 [5. Primary skin irritation index (PII value)]
From the viewpoint of improving the safety of the ink composition, the PII value of the ink composition is preferably less than 2, more preferably less than 2.00, and even more preferably less than 1.70. A method for calculating the PII value of the ink composition is described in Examples.
　一次皮膚刺激性インデックスが２未満である重合化合物の含有量は、インク組成物の安全性を向上させる観点から、重合性化合物１００質量部（重合性化合物の総質量１００質量部）に対して３質量部以上３５質量部以下であることが好ましく、５質量部以上３２質量部以下であることがより好ましい。 The content of the polymerization compound having a primary skin irritation index of less than 2 is 3 with respect to 100 parts by mass of the polymerizable compound (total mass of the polymerizable compound of 100 parts by mass) from the viewpoint of improving the safety of the ink composition. The mass is preferably 35 parts by mass or more and more preferably 5 parts by mass or more and 32 parts by mass or less.
［６．用途］
　インク組成物は、特に一次皮膚刺激性インデックスＰＩＩ値が２未満である場合には、人の手に触れる画像形成物の用途に適している。インク組成物は、ラベルとして食品包装の表面に記録するための食品包装記録用のインク組成物として用いることができる。ラベルとしては、たとえば、商品名、商品の成分、メーカー名、製造年月日、ロット番号、および注意書きが挙げられる。 [6. Application]
The ink composition is suitable for use in an image-forming product that touches a human hand, particularly when the primary skin irritation index PII value is less than 2. The ink composition can be used as an ink composition for food packaging recording for recording on the surface of food packaging as a label. Examples of the label include a product name, a product component, a manufacturer name, a manufacturing date, a lot number, and a note.
［７．光硬化型インクジェット記録用インク組成物の調製方法］
　インク組成物の調製方法は、従来から公知の調製方法を使用することができる。以下、インク組成物が着色材として顔料を含む場合の好適な調製方法を説明する。分散機を用いて、着色剤と、重合性化合物の一部と、必要に応じて任意の成分（より具体的には、顔料分散剤等）とを予備混合（プレミックス）し、各成分を溶解または分散させることで一次分散体を調製する。分散機としては、たとえば、ディスパ、容器駆動媒体ミル（より具体的には、ボールミル、遠心ミル、および遊星ボールミル等）、高速回転ミル（より具体的には、サンドミル等）、および媒体撹拌ミル（より具体的には、撹拌槽型ミル等）が挙げられる。 [7. Method for preparing photocurable ink composition for inkjet recording]
As a method for preparing the ink composition, a conventionally known preparation method can be used. Hereinafter, a suitable preparation method when the ink composition contains a pigment as a colorant will be described. Using a disperser, colorants, a part of the polymerizable compound, and optional components (more specifically, pigment dispersants, etc.) are premixed (premixed) as necessary, and each component is mixed. A primary dispersion is prepared by dissolving or dispersing. Examples of the disperser include a disperser, a container drive medium mill (more specifically, a ball mill, a centrifugal mill, a planetary ball mill, and the like), a high-speed rotating mill (more specifically, a sand mill, etc.), and a medium agitation mill (more specifically, More specifically, a stirring tank type mill or the like may be mentioned.
　次いで、得られた一次分散液に、残りの重合性化合物と、光重合開始剤と、界面活性剤（表面張力調整剤）と、必要に応じて添加剤（より具体的には、ゲル化防止剤等）を添加し、攪拌機を用いて均一に混合する。攪拌機としては、たとえば、ディスパ、スリーワンモーター、ホモジナイザー、およびマグネチックスターラーが挙げられる。このようにしてインク組成物を得ることができる。また、ラインミキサーなどの混合機を用いて、インク組成物を混合してもよい。さらに、インク組成物中の粒子をより微細化する目的でビーズミルおよび高圧噴射ミルのような分散機を用いて、インク組成物を混合してもよい。 The resulting primary dispersion is then mixed with the remaining polymerizable compound, photopolymerization initiator, surfactant (surface tension modifier), and additives (more specifically, gelling prevention) as required. Agent) and mix uniformly using a stirrer. Examples of the stirrer include a disperser, a three-one motor, a homogenizer, and a magnetic stirrer. In this way, an ink composition can be obtained. Further, the ink composition may be mixed using a mixer such as a line mixer. Furthermore, the ink composition may be mixed using a disperser such as a bead mill and a high-pressure jet mill for the purpose of further reducing the particles in the ink composition.
　＜インクセット＞
　インクセットは、光硬化型インクジェット記録用インク組成物を含む。インクセットは、複数色（たとえば、シアン色、マゼンタ色、イエロー色、ブラック色、およびホワイト色）の光硬化型インクジェット記録用カラーインク組成物を含む。光硬化型インクジェット記録用カラーインク組成物は、たとえば、着色材を含む光硬化型インクジェット記録用インク組成物である。 <Ink set>
The ink set includes a photocurable ink composition for inkjet recording. The ink set includes a color ink composition for photocurable inkjet recording of a plurality of colors (for example, cyan, magenta, yellow, black, and white). The photocurable ink composition for ink jet recording is, for example, a photocurable ink composition for ink jet recording containing a coloring material.
　以下、実施例を用いて本発明を更に説明する。なお、本発明は実施例の範囲に何ら限定されるものではない。特に断りのない限り、「％」は「質量％」を示し、「部」は「質量部」を示す。 Hereinafter, the present invention will be further described using examples. The present invention is not limited to the scope of the examples. Unless otherwise specified, “%” indicates “% by mass”, and “part” indicates “part by mass”.
［１．インク組成物の調製］
（１－１．顔料分散体の調製）
（ブラック顔料分散体）
　顔料　カーボンブラック顔料（デグサ社製「Ｓｐｅｃｉａｌ　Ｂｌａｃｋ２５０」　　１５．０部
　顔料分散剤　ソルスパース３２０００(ルーブリゾール社製)　　　　６．０部
　二官能アクリルモノマー　　ジプロピレングリコールジアクリレート（ＤＰＧＤＡ）　７９．０部
　上記材料（顔料、顔料分散剤、および二官能アクリルモノマー）をプラスチック製ビンに投入した。ハイスピードミキサーを用いて、プラスチック製ビンの内容物を均一になるまで撹拌し、ミルベースを得た。次いで、ペイントコンディショナー（東洋精機社製）を用いて、ミルベースを２時間分散させて、ブラック顔料分散体を得た。 [1. Preparation of ink composition]
(1-1. Preparation of pigment dispersion)
(Black pigment dispersion)
Pigment Carbon black pigment (“Special Black 250” manufactured by Degussa 15.0 parts Pigment dispersant Solsperse 32000 (manufactured by Lubrizol) 6.0 parts Bifunctional acrylic monomer Dipropylene glycol diacrylate (DPGDA) 79.0 parts Above materials ( Pigment, pigment dispersant, and bifunctional acrylic monomer) were charged into a plastic bottle, and the contents of the plastic bottle were agitated using a high speed mixer to obtain a mill base. (Toyo Seiki Co., Ltd.) was used to disperse the mill base for 2 hours to obtain a black pigment dispersion.
（シアン顔料分散体、マゼンタ顔料分散体、イエロー顔料分散体）
　ブラック色の顔料としてのカーボンブラック顔料（デグサ社製「Ｓｐｅｃｉａｌ　Ｂｌａｃｋ２５０」）を、シアン色の顔料としての銅フタロシアニン顔料（クラリアント社製「Ｐ－ＢＦＳ」）、マゼンタ色の顔料としてのキナクリドン顔料（ＢＡＳＦ社製「ＲＴ－３５５Ｄ」）、およびイエロー色の顔料としてのジスアゾ顔料（クラリアント社製「４ＧＣ」）に変更した以外は、ブラック顔料分散体の調製方法と同様にしてそれぞれシアン顔料分散体、マゼンタ顔料分散体、およびイエロー顔料分散体を調製した。 (Cyan pigment dispersion, magenta pigment dispersion, yellow pigment dispersion)
Carbon black pigment (“Special Black 250” manufactured by Degussa) as a black pigment, copper phthalocyanine pigment (“P-BFS” manufactured by Clariant) as a cyan pigment, and quinacridone pigment (BASF as a magenta pigment) “RT-355D”) and a disazo pigment as a yellow pigment (“4GC” manufactured by Clariant), respectively, in the same manner as the preparation of the black pigment dispersion, respectively, cyan pigment dispersion, magenta A pigment dispersion and a yellow pigment dispersion were prepared.
（ホワイト顔料分散体）
　ブラック色の顔料としてのカーボンブラック顔料（デグサ社製「Ｓｐｅｃｉａｌ　Ｂｌａｃｋ２５０」）１５．０部をホワイト色の顔料としての酸化チタン顔料（石原産業社製「ＣＲ－６０」）５０．０部に変更し、ジプロピレングリコールジアクリレートの添加量を７９．０部から４５．０部に変更した以外は、ブラック顔料分散体の調製方法と同様にしてホワイト顔料分散体を調製した。 (White pigment dispersion)
15.0 parts of carbon black pigment (“Special Black 250” manufactured by Degussa) as a black pigment was changed to 50.0 parts of titanium oxide pigment (“CR-60” manufactured by Ishihara Sangyo Co., Ltd.) as a white pigment. A white pigment dispersion was prepared in the same manner as the black pigment dispersion except that the amount of dipropylene glycol diacrylate added was changed from 79.0 parts to 45.0 parts.
（１－２．インク組成物（Ａ－１）の調製）
　ブラック顔料分散体を含むプラスチック製ビンに、（メタ）アクリル酸エステル類（Ｉ）としてのアクリル酸２－（２－ビニロキシエトキシ）エチル（ＶＥＥＡ）と、単官能モノマーとしてのイソボルニルアクリレート（ＩＢＯＡ）と、多官能（メタ）アクリルモノマーとしてのジプロピレングリコールジアクリレート（ＤＰＧＤＡ）、ネオペンチルグリコールヒドロキシピバリン酸エステルジアクリレート（ＨＰＮＤＡ）、およびトリプロピレングリコールジアクリレート（ＴＰＧＤＡ）と、光重合開始剤としての２，４，６－トリメチルベンゾイル－ジフェニル－フォスフィンオキサイド（ＢＡＳＦ社製「ＩＲＧＡＣＵＲＥ（登録商標）ＴＰＯ」）と、界面活性剤としてのポリエーテル変性ポリジメチルシロキサン（ビックケミ－社製「ＢＹＫ（登録商標）－ＵＶ３５１０」）と、重合禁止剤としてのブチルヒドロキシトルエン（ＢＨＴ）とを更に投入した。マグネチックスターラーを用いて、ブラック顔料分散体および追加投入した成分を３０分撹拌し、混合物を得た。撹拌後、グラスフィルター（桐山製作所製）を用いて、混合物を吸引ろ過し、インク組成物（Ａ－１）を調製した。表１にインク組成物（Ａ－１）の組成および各成分の配合量を示す。 (1-2. Preparation of ink composition (A-1))
In a plastic bottle containing a black pigment dispersion, 2- (2-vinyloxyethoxy) ethyl acrylate (VEEA) as (meth) acrylic acid esters (I) and isobornyl acrylate (Monofunctional monomer) IBOA), dipropylene glycol diacrylate (DPGDA), neopentyl glycol hydroxypivalate ester diacrylate (HPNDA), and tripropylene glycol diacrylate (TPGDA) as a polyfunctional (meth) acrylic monomer, and a photopolymerization initiator 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide ("IRGACURE (registered trademark) TPO" manufactured by BASF) and polyether-modified polydimethylsiloxane (BIC Chem. And YK (TM) -UV3510 "), and was further charged butylhydroxytoluene as a polymerization inhibitor (BHT). Using a magnetic stirrer, the black pigment dispersion and the additionally charged components were stirred for 30 minutes to obtain a mixture. After stirring, the mixture was suction filtered using a glass filter (manufactured by Kiriyama Seisakusho) to prepare an ink composition (A-1). Table 1 shows the composition of the ink composition (A-1) and the amount of each component.
（１－３．インク組成物（Ａ－２）～（Ａ－７）およびインク組成物（Ｂ－１）～（Ｂ－９）の調製）
　表１および表２に記載の成分および含有量に基づいて、インク組成物（Ａ－１）の調製方法と同様にしてインク組成物（Ａ－２）～（Ａ－７）およびインク組成物（Ｂ－１）～（Ｂ－９）を調製した。たとえば、インク組成物（Ａ－２）は、単官能モノマーをイソボルニルアクリレート（ＩＢＯＡ）９部からイソボルニルアクリレート（ＩＢＯＡ）５部およびアクリロイルモルフォリン（ＡＣＭＯ）４部に変更した以外は、インク組成物（Ａ－１）の調製方法と同様にして調製した。また、インク組成物（Ａ－４）は、ブラック顔料分散体をシアン顔料分散体に変更し、単官能モノマーをイソボルニルアクリレート（ＩＢＯＡ）９部から３，３，５－トリメチルシクロヘキシルアクリレート（ＴＭＣＨＡ）５部に変更し、多官能（メタ）アクリルモノマーをネオペンチルグリコールヒドロキシピバリン酸エステルジアクリレート（ＨＰＮＤＡ）１２部およびトリプロピレングリコールジアクリレート（ＴＰＧＤＡ）９．５部からネオペンチルグリコールプロピレンオキシドジアクリレート（ＮＰＧＰＯＤＡ）２５．５部に変更した以外は、インク組成物（Ａ－１）の調製方法と同様にして調製した。 (1-3. Preparation of Ink Compositions (A-2) to (A-7) and Ink Compositions (B-1) to (B-9))
Based on the components and contents described in Table 1 and Table 2, ink compositions (A-2) to (A-7) and an ink composition ( B-1) to (B-9) were prepared. For example, in the ink composition (A-2), the monofunctional monomer was changed from 9 parts of isobornyl acrylate (IBOA) to 5 parts of isobornyl acrylate (IBOA) and 4 parts of acryloylmorpholine (ACMO). It was prepared in the same manner as the ink composition (A-1). In addition, in the ink composition (A-4), the black pigment dispersion was changed to a cyan pigment dispersion, and the monofunctional monomer was changed from 9 parts of isobornyl acrylate (IBOA) to 3,3,5-trimethylcyclohexyl acrylate (TMCHA). ) 5 parts, polyfunctional (meth) acrylic monomer from neopentyl glycol hydroxypivalate ester diacrylate (HPNDA) 12 parts and tripropylene glycol diacrylate (TPGDA) 9.5 parts neopentyl glycol propylene oxide diacrylate (NPGPODA) Prepared in the same manner as the preparation method of the ink composition (A-1) except that the amount was changed to 25.5 parts.
（重合体のガラス転移温度の測定方法）
　重合性化合物の１種（単官能（メタ）アクリルモノマー及び多官能（メタ）アクリルモノマーのうちの１種）と、光重合開始剤として１－ヒドロキシ－シクロヘキシル－フェニルケトン（チバ社製「ＩＲＧＡＣＵＲＥ１８４」）とを、質量比（重合性化合物／光重合開始剤）９５／５で混合し、溶液を調製した。バーコータ（＃２０）を用いてこの溶液をガラス基板上に塗布して均一な塗布膜を形成した。次に、メタルハライドランプを用いて、積算光量２００ｍＪ／ｃｍ２の条件で紫外線を塗布膜に照射して硬化させ、硬化物を得た。得られた硬化物をガラス基板から剥離し、測定試料とした。熱重量測定装置（マックサイエンス社製「ＴＧ－ＧＤＡ」）を用いて、測定試料のガラス転移温度（単位：温度）を測定した。測定した測定試料のガラス転移温度を、単官能（メタ）アクリルモノマー又は多官能（メタ）アクリルモノマーの重合体のガラス転移温度とした。得られたガラス転移温度を表１および表２にまとめた。なお、測定条件は、窒素雰囲気下、昇温速度１０℃／分、測定温度範囲－１００～１８０℃で行った。 (Measurement method of glass transition temperature of polymer)
One type of polymerizable compound (one type of monofunctional (meth) acrylic monomer and polyfunctional (meth) acrylic monomer) and 1-hydroxy-cyclohexyl-phenyl ketone (“IRGACURE184” manufactured by Ciba) as a photopolymerization initiator ) In a mass ratio (polymerizable compound / photopolymerization initiator) 95/5 to prepare a solution. This solution was applied on a glass substrate using a bar coater (# 20) to form a uniform coating film. Next, using a metal halide lamp, the coating film was irradiated with ultraviolet rays under the condition of an integrated light quantity of 200 mJ / cm 2 to be cured, thereby obtaining a cured product. The obtained cured product was peeled from the glass substrate to obtain a measurement sample. The glass transition temperature (unit: temperature) of the measurement sample was measured using a thermogravimetric measurement device (“TG-GDA” manufactured by Mac Science). The glass transition temperature of the measured measurement sample was defined as the glass transition temperature of a polymer of monofunctional (meth) acrylic monomer or polyfunctional (meth) acrylic monomer. The glass transition temperatures obtained are summarized in Tables 1 and 2. The measurement conditions were a nitrogen atmosphere, a temperature increase rate of 10 ° C./min, and a measurement temperature range of −100 to 180 ° C.
　表１および表２中、欄「Ｔｇ」は、各成分の重合体のガラス転移温度を示す。欄「成分」のアルファベットは、表３に示す成分の略称または型番を示す。欄「粘度」は、２５℃における各成分の粘度を示す。欄「実施例１」～「実施例７」および欄「比較例１」～「比較例９」は、それぞれインク組成物（Ａ－１）～（Ａ－７）およびインク組成物（Ｂ－１）～（Ｂ－９）の各成分の含有量（単位：部）を示す。 In Tables 1 and 2, the column “Tg” indicates the glass transition temperature of the polymer of each component. The alphabet in the column “component” indicates the abbreviation or model number of the component shown in Table 3. The column “viscosity” indicates the viscosity of each component at 25 ° C. The columns “Example 1” to “Example 7” and the columns “Comparative Example 1” to “Comparative Example 9” indicate the ink compositions (A-1) to (A-7) and the ink composition (B-1), respectively. ) To (B-9) indicates the content (unit: part) of each component.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表３にインク組成物の成分の詳細を示す。 Table 3 shows details of the components of the ink composition.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
［２．評価方法］
（２－１．インク組成物の吐出安定性の評価：インク組成物の粘度測定）
　ＪＩＳ　Ｚ８８０３に準拠した方法により、Ｒ１００型粘度計（東機産業社製）を用いて、温度２５℃およびコーン回転数５ｒｐｍの条件下で、インク組成物の粘度を測定した。得られた粘度（単位：ｍＰａ・ｓ）を表４に示す。
　なお、２５℃でのインク組成物の粘度が１０．５ｍＰａ・ｓ以下である場合、インク組成物の吐出安定性が実用上問題ない水準であると評価した。２５℃でのインク組成物の粘度が１０．５ｍＰａ・ｓ以下であると、インクジェット記録装置の標準的な使用条件（通常４０℃）において、インクジェットヘッドのノズルからインク組成物が安定して吐出されるためである。 [2. Evaluation method]
(2-1. Evaluation of ejection stability of ink composition: measurement of viscosity of ink composition)
The viscosity of the ink composition was measured using a R100 viscometer (manufactured by Toki Sangyo Co., Ltd.) under the conditions of a temperature of 25 ° C. and a cone rotation speed of 5 rpm by a method based on JIS Z8803. Table 4 shows the obtained viscosity (unit: mPa · s).
In addition, when the viscosity of the ink composition at 25 ° C. was 10.5 mPa · s or less, it was evaluated that the ejection stability of the ink composition was at a level with no practical problem. When the viscosity of the ink composition at 25 ° C. is 10.5 mPa · s or less, the ink composition is stably ejected from the nozzles of the inkjet head under the standard use conditions (usually 40 ° C.) of the inkjet recording apparatus. Because.
（２－２．インク組成物の安全性の評価：ＰＩＩ値の算出）
　表１および表２に記載されたインク組成物の成分のＰＩＩ値およびインク組成物の組成に基づき、インク組成物のＰＩＩ値を算出した。得られたＰＩＩ値を表４に示す。 (2-2. Evaluation of safety of ink composition: calculation of PII value)
Based on the PII values of the components of the ink composition described in Tables 1 and 2 and the composition of the ink composition, the PII value of the ink composition was calculated. The obtained PII values are shown in Table 4.
（２－３．密着性の評価：クロスカット試験）
　滴サイズ７ｐＬおよび解像度６００×６００ｄｐｉの条件で、インクジェットヘッドからインク組成物を吐出させて基材（白ＰＥＴ）上に塗布し、塗布膜を形成した。このインクジェットヘッドは、シングルパス方式のインクジェット記録装置に搭載するインクジェットヘッドである。紫外線ＬＥＤ（日亜化学工業社製「ＮＣＣＵ００１Ｅ」）を用いて、トータル照射光量が３００ｍＪ／ｃｍ２となるように塗布膜に紫外線を照射して、塗布膜を硬化させ、基材上に塗膜（膜厚３μｍ）を形成した。その結果、密着性測定用試料を得た。次いで、密着性測定用試料の塗膜表面をクロスカットし、粘着シート（ニチバン社製「セロテープ（登録商標）」）の粘着層側の面を貼り付け、粘着シートを引き剥がした。塗膜の状態を目視で観察した。観察結果から密着性を下記評価基準に基づいて評価した。評価Ｓ（特に良好）、Ａ（良好）、およびＢ（良）を密着性が実用上問題のない水準であると判断した。密着性の評価結果を表４に示す。なお、密着性の評価は、温度２５℃で実施された。
（密着性の評価基準）
Ｓ（特に良好）：塗膜が全く剥離しない。
Ａ（良好）　　：塗膜がわずかに剥離しない。
Ｂ（良）　　　：塗膜が一部剥離する。
Ｃ（不良）　　：粘着シートを貼り付けた部分の塗膜の全面が剥離する。 (2-3. Evaluation of adhesion: cross-cut test)
Under the conditions of a droplet size of 7 pL and a resolution of 600 × 600 dpi, the ink composition was ejected from an inkjet head and applied onto a substrate (white PET) to form a coating film. This inkjet head is an inkjet head mounted on a single-pass inkjet recording apparatus. Using an ultraviolet LED (“NCCU001E” manufactured by Nichia Corporation), the coating film is irradiated with ultraviolet light so that the total irradiation light quantity becomes 300 mJ / cm 2 , the coating film is cured, and the coating film is formed on the substrate. (Film thickness 3 μm) was formed. As a result, a sample for measuring adhesion was obtained. Subsequently, the coating film surface of the sample for adhesion measurement was cross-cut, the surface of the pressure-sensitive adhesive sheet (“Cellotape (registered trademark)” manufactured by Nichiban Co., Ltd.) was attached, and the pressure-sensitive adhesive sheet was peeled off. The state of the coating film was visually observed. From the observation results, the adhesion was evaluated based on the following evaluation criteria. Evaluations S (particularly good), A (good), and B (good) were judged to be at a level where there was no problem in practical use. Table 4 shows the results of evaluation of adhesion. In addition, evaluation of adhesiveness was implemented at the temperature of 25 degreeC.
(Adhesion evaluation criteria)
S (particularly good): The coating film does not peel at all.
A (good): The coating film does not peel slightly.
B (good): Part of the coating film peels off.
C (defect): The entire surface of the coating film where the pressure-sensitive adhesive sheet is pasted peels off.
（２－４．塗膜強度の評価：鉛筆硬度試験）
　滴サイズ７ｐＬおよび解像度６００×６００ｄｐｉの条件で、インクジェットヘッドからインク組成物を吐出させて基材（白ＰＥＴ）上に塗布し、塗布膜を形成した。このインクジェットヘッドは、シングルパス方式のインクジェット記録装置に搭載するインクジェットヘッドである。紫外線ＬＥＤ（日亜化学工業社製「ＮＣＣＵ００１Ｅ」）を用いて、トータル照射光量が３００ｍＪ／ｃｍ２となるように塗布膜に紫外線を照射して、塗布膜を硬化させ、基材上に塗膜（膜厚３μｍ）を形成した。その結果、塗膜強度測定用試料を得た。このように硬化させた塗膜強度測定用試料の鉛筆硬度を測定し、下記の基準で評価した。なお、日本工業規格（ＪＩＳ）Ｋ５４００に規定された鉛筆硬度の測定方法に基づき、の表面性試験機（新東科学社製「ＨＥＩＤＯＮ－１４ＤＲ」）を用いて測定した。評価Ｓ（特に良好）、Ａ（良好）、およびＢ（良）を塗膜強度が実用上問題のない水準であると判断した。評価結果を表４に示す。
（塗膜強度の評価基準）
Ｓ（特に良好）：鉛筆硬度が４Ｈ以上である。
Ａ（良好）　　：鉛筆硬度が３Ｈ以上４Ｈ未満である。
Ｂ（良）　　　：鉛筆硬度がＨＢ以上３Ｈ未満である。
Ｃ（不良）　　：鉛筆硬度がＨＢ未満である。 (2-4. Evaluation of coating strength: pencil hardness test)
Under the conditions of a droplet size of 7 pL and a resolution of 600 × 600 dpi, the ink composition was ejected from an inkjet head and applied onto a substrate (white PET) to form a coating film. This inkjet head is an inkjet head mounted on a single-pass inkjet recording apparatus. Using an ultraviolet LED (“NCCU001E” manufactured by Nichia Corporation), the coating film is irradiated with ultraviolet light so that the total irradiation light quantity becomes 300 mJ / cm 2 , the coating film is cured, and the coating film is formed on the substrate. (Film thickness 3 μm) was formed. As a result, a sample for coating film strength measurement was obtained. The pencil hardness of the sample for coating film strength measurement thus cured was measured and evaluated according to the following criteria. It was measured using a surface property tester (“HEIDON-14DR” manufactured by Shinto Kagaku Co.) based on the pencil hardness measurement method specified in Japanese Industrial Standard (JIS) K5400. Evaluation S (particularly good), A (good), and B (good) were judged that the coating film strength was at a level having no practical problem. The evaluation results are shown in Table 4.
(Evaluation criteria for coating strength)
S (particularly good): Pencil hardness is 4H or more.
A (good): Pencil hardness is 3H or more and less than 4H.
B (good): Pencil hardness is HB or more and less than 3H.
C (defect): Pencil hardness is less than HB.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表１に示すように、インク組成物（Ａ－１）～（Ａ－７）は、重合性化合物と光重合開始剤とを含有していた。重合性化合物は、（メタ）アクリル酸エステル類（Ｉ）と、単官能モノマーと、多官能（メタ）アクリルモノマーとを含んでいた。単官能モノマーは、単官能（メタ）アクリルモノマーおよびアクリルアミド系モノマーのうちの少なくとも１種であった。単官能モノマーの含有率は１％以上９％以下の範囲に含まれる数値であった。多官能（メタ）アクリルモノマーの含有率は、１０％以上４０％以下の範囲に含まれる数値であった。単官能（メタ）アクリルモノマーの重合体のガラス転移温度は３０℃以上であった。多官能（メタ）アクリルモノマーの重合体のガラス転移温度が３０℃以上であった。 As shown in Table 1, the ink compositions (A-1) to (A-7) contained a polymerizable compound and a photopolymerization initiator. The polymerizable compound contained (meth) acrylic acid esters (I), a monofunctional monomer, and a polyfunctional (meth) acrylic monomer. The monofunctional monomer was at least one of a monofunctional (meth) acryl monomer and an acrylamide monomer. The content of the monofunctional monomer was a numerical value included in the range of 1% to 9%. The content of the polyfunctional (meth) acrylic monomer was a value included in the range of 10% to 40%. The glass transition temperature of the polymer of the monofunctional (meth) acrylic monomer was 30 ° C. or higher. The glass transition temperature of the polymer of the polyfunctional (meth) acrylic monomer was 30 ° C. or higher.
　表４に示すように、インク組成物（Ａ－１）～（Ａ－７）では、粘度が１０．５ｍＰａ・ｓ以下であり、ＰＩＩ値が１．８３以下であり、密着性の評価はいずれもＡ（良好）であり、塗膜強度の評価は、Ｓ（特に良好）またはＡ（良好）であった。 As shown in Table 4, the ink compositions (A-1) to (A-7) had a viscosity of 10.5 mPa · s or less and a PII value of 1.83 or less. Was also A (good), and the evaluation of the coating strength was S (particularly good) or A (good).
　表２に示すように、インク組成物（Ｂ－１）～（Ｂ－２）は、（メタ）アクリル酸エステル類（Ｉ）を含んでいなかった。インク組成物（Ｂ－３）では、単官能モノマーの含有率が９％より大きかった。インク組成物（Ｂ－１）～（Ｂ－２）および（Ｂ－４）～（Ｂ－７）では、多官能（メタ）アクリルモノマーの含有率が１０％未満または４０％より大きかった。インク組成物（Ｂ－４）～（Ｂ－５）では、単官能（メタ）アクリルモノマーの重合体のガラス転移温度Ｔｇが３０℃未満であった。インク組成物（Ｂ－８）～（Ｂ－９）では、多官能（メタ）アクリルモノマーの重合体のガラス転移温度Ｔｇは３０℃未満であった。 As shown in Table 2, the ink compositions (B-1) to (B-2) did not contain (meth) acrylic acid esters (I). In the ink composition (B-3), the content of the monofunctional monomer was greater than 9%. In the ink compositions (B-1) to (B-2) and (B-4) to (B-7), the polyfunctional (meth) acrylic monomer content was less than 10% or greater than 40%. In the ink compositions (B-4) to (B-5), the glass transition temperature Tg of the polymer of the monofunctional (meth) acrylic monomer was less than 30 ° C. In the ink compositions (B-8) to (B-9), the glass transition temperature Tg of the polyfunctional (meth) acrylic monomer polymer was less than 30 ° C.
　表４に示すように、インク組成物（Ｂ－１）～（Ｂ－２）、（Ｂ－４）～（Ｂ－５）および（Ｂ－７）～（Ｂ－９）では、粘度が１３．１ｍＰａ・ｓ以上であった。インク組成物（Ｂ－１）～（Ｂ－３）および（Ｂ－８）では、ＰＩＩ値が２．００以上であった。インク組成物（Ｂ－３）～（Ｂ－６）および（Ｂ－８）～（Ｂ－９）では、Ｃ（不良）であった。インク組成物（Ｂ－１）～（Ｂ－９）では、粘度が１０．５ｍＰａ・ｓ以下であること、ＰＩＩ値が２．００未満であること、密着性の評価Ｓ（特に良好）またはＡ（良好）および塗膜強度の評価Ｓ（特に良好）またはＡ（良好）であることのすべてを満たさなかった。 As shown in Table 4, in the ink compositions (B-1) to (B-2), (B-4) to (B-5) and (B-7) to (B-9), the viscosity is 13 It was 1 mPa · s or more. In the ink compositions (B-1) to (B-3) and (B-8), the PII value was 2.00 or more. In the ink compositions (B-3) to (B-6) and (B-8) to (B-9), C (poor) was obtained. In the ink compositions (B-1) to (B-9), the viscosity is 10.5 mPa · s or less, the PII value is less than 2.00, the adhesion evaluation S (particularly good) or A (Good) and coating strength evaluation S (particularly good) or A (good) were not satisfied.
　以上から、インク組成物（Ａ－１）～（Ａ－７）は、インク組成物（Ｂ－１）～（Ｂ－９）に対してインクの吐出安定性および安全性に優れ、かつ得られる塗膜の密着性および強度が優れることが明らかである。 From the above, the ink compositions (A-1) to (A-7) are superior in ink ejection stability and safety to the ink compositions (B-1) to (B-9) and can be obtained. It is clear that the adhesion and strength of the coating film are excellent.
　本発明の光硬化型インクジェット記録用インク組成物は、他の光硬化型インクジェット記録用インク組成物とともに、インクジェット記録用インクセットして好適に用いることができる。 The photocurable ink composition for ink jet recording of the present invention can be suitably used as an ink set for ink jet recording together with other photocurable ink composition for ink jet recording.

Claims (11)

  1. 　シングルパス方式のインクジェット記録装置に用いる光硬化型インクジェット記録用インク組成物であって、
    　重合性化合物と光重合開始剤とを含有し、
    　前記重合性化合物は、
    　下記一般式（Ｉ）：
    　　ＣＨ２＝ＣＲ１－ＣＯＯＲ２－Ｏ－ＣＨ＝ＣＨ－Ｒ３・・・（Ｉ）
    （前記一般式（Ｉ）中、Ｒ１は水素原子またはメチル基を表し、Ｒ２は炭素原子数２以上２０以下の２価の有機残基を表し、Ｒ３は水素原子または炭素原子数１以上１１以下の１価の有機残基を表す）
    で表されるビニルエーテル基含有（メタ）アクリル酸エステル類と、
    　アクリルアミド系モノマーおよび単官能（メタ）アクリルモノマーからなる群から選択される少なくとも１種の単官能モノマーと、
    　多官能（メタ）アクリルモノマーとを含み、
    　前記単官能モノマーの含有率は、１質量％以上９質量％以下であり、
    　前記多官能（メタ）アクリルモノマーの含有率は、５質量％以上５０質量％以下であり、
    　単官能（メタ）アクリルモノマーの重合体のガラス転移温度が３０℃以上であり、
    　多官能（メタ）アクリルモノマーの重合体のガラス転移温度が３０℃以上である、光硬化型インクジェット記録用インク組成物。     A photocurable ink jet recording ink composition for use in a single pass ink jet recording apparatus,
    Containing a polymerizable compound and a photopolymerization initiator,
    The polymerizable compound is
    The following general formula (I):
    CH 2 = CR 1 —COOR 2 —O—CH═CH—R 3 (I)
    (In the general formula (I), R 1 represents a hydrogen atom or a methyl group, R 2 represents a divalent organic residue having 2 to 20 carbon atoms, and R 3 represents a hydrogen atom or 1 carbon atom. Represents a monovalent organic residue of 11 or less)
    A vinyl ether group-containing (meth) acrylic acid ester represented by:
    At least one monofunctional monomer selected from the group consisting of acrylamide monomers and monofunctional (meth) acrylic monomers;
    A polyfunctional (meth) acrylic monomer,
    The content of the monofunctional monomer is 1% by mass or more and 9% by mass or less,
    The content of the polyfunctional (meth) acrylic monomer is 5% by mass or more and 50% by mass or less,
    The glass transition temperature of the polymer of monofunctional (meth) acrylic monomer is 30 ° C. or higher,
    A photocurable ink composition for ink jet recording, wherein the polyfunctional (meth) acrylic monomer polymer has a glass transition temperature of 30 ° C. or higher.
  2. 　一次皮膚刺激性インデックスは２未満である、請求項１に記載の光硬化型インクジェット記録用インク組成物。 The photocurable ink jet recording ink composition according to claim 1, wherein the primary skin irritation index is less than 2.
  3. 　一次皮膚刺激性インデックスが２未満である重合性化合物の含有量は、前記重合性化合物１００質量部に対して３質量部以上３５質量部以下である、請求項１または２に記載の光硬化型インクジェット記録用インク組成物。 The photocurable type according to claim 1 or 2, wherein the content of the polymerizable compound having a primary skin irritation index of less than 2 is 3 parts by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the polymerizable compound. Ink composition for inkjet recording.
  4. 　前記多官能（メタ）アクリルモノマーは、鎖状構造または脂環式構造を有する、請求項１～３のいずれかに記載の光硬化型インクジェット記録用インク組成物。 4. The photocurable ink composition for ink jet recording according to claim 1, wherein the polyfunctional (meth) acrylic monomer has a chain structure or an alicyclic structure.
  5. 　前記多官能（メタ）アクリルモノマーは、鎖状構造を有する二官能（メタ）アクリルモノマーと、脂環式構造を有する二官能（メタ）アクリルモノマーとを含む、請求項１～４のいずれかに記載の光硬化型インクジェット記録用インク組成物。 The polyfunctional (meth) acrylic monomer includes a bifunctional (meth) acrylic monomer having a chain structure and a bifunctional (meth) acrylic monomer having an alicyclic structure. The photocurable ink composition for inkjet recording according to the description.
  6. 　前記アクリルアミド系モノマーはアクリロイルモルフォリンである、請求項１～５のいずれかに記載の光硬化型インクジェット記録用インク組成物。 6. The photocurable ink jet recording ink composition according to claim 1, wherein the acrylamide monomer is acryloylmorpholine.
  7. 　前記単官能（メタ）アクリルモノマーは、イソボルニルアクリレート、３，３，５－トリメチルシクロヘキシルアクリレート、環状トリメチロールプロパンホルマールアクリレートおよびイソボルニルメタクリレートからなる群から選択される少なくとも１種を含む、請求項１～６のいずれかに記載の光硬化型インクジェット記録用インク組成物。 The monofunctional (meth) acrylic monomer includes at least one selected from the group consisting of isobornyl acrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclic trimethylolpropane formal acrylate, and isobornyl methacrylate. Item 7. The photocurable ink composition for ink jet recording according to any one of Items 1 to 6.
  8. 　前記多官能（メタ）アクリルモノマーは、ジシクロペンタニルジアクリレート、メチル－１，５－ペンタンジオールジアクリレート、ジプロピレングリコールジアクリレート、ネオペンチルグリコールヒドロキシピバリン酸エステルジアクリレート、１，１０－デカンジオールジアクリレート、トリプロピレングリコールジアクリレート、ネオペンチルグリコールプロピレンオキシドジアクリレートおよび１，９－ノナンジオールジアクリレートからなる群から選択される少なくとも１種を含む、請求項１～７のいずれかに記載の光硬化型インクジェット記録用インク組成物。 The polyfunctional (meth) acrylic monomer is dicyclopentanyl diacrylate, methyl-1,5-pentanediol diacrylate, dipropylene glycol diacrylate, neopentyl glycol hydroxypivalate ester diacrylate, 1,10-decanediol. The light according to any one of claims 1 to 7, comprising at least one selected from the group consisting of diacrylate, tripropylene glycol diacrylate, neopentyl glycol propylene oxide diacrylate and 1,9-nonanediol diacrylate. A curable ink composition for inkjet recording.
  9. 　前記ビニルエーテル基含有（メタ）アクリル酸エステル類の含有率は、２０質量％以上５０質量％以下である、請求項１～８のいずれかに記載の光硬化型インクジェット記録用インク組成物。 The photocurable ink composition for ink jet recording according to any one of claims 1 to 8, wherein a content of the vinyl ether group-containing (meth) acrylic acid ester is 20% by mass or more and 50% by mass or less.
  10. 　食品包装記録用である、請求項１～９のいずれかに記載の光硬化型インクジェット記録用インク組成物。 The photocurable ink jet recording ink composition according to any one of claims 1 to 9, which is used for food packaging recording.
  11. 　請求項１～１０のいずれかに記載の光硬化型インクジェット記録用インク組成物を含む、インクセット。 An ink set comprising the photocurable ink jet recording ink composition according to any one of claims 1 to 10.
PCT/JP2018/034285 2018-02-01 2018-09-14 Photocurable ink composition for ink-jet recording and ink set WO2019150644A1 (en)

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