WO2018074604A1 - Coated white paperboard - Google Patents

Coated white paperboard Download PDF

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Publication number
WO2018074604A1
WO2018074604A1 PCT/JP2017/038076 JP2017038076W WO2018074604A1 WO 2018074604 A1 WO2018074604 A1 WO 2018074604A1 JP 2017038076 W JP2017038076 W JP 2017038076W WO 2018074604 A1 WO2018074604 A1 WO 2018074604A1
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WO
WIPO (PCT)
Prior art keywords
coating
coating layer
weight
pigment
paper
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PCT/JP2017/038076
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French (fr)
Japanese (ja)
Inventor
周平 稲田
宗信 神代
吉松　丈博
大典 大庭
和也 ▲高▼橋
Original Assignee
日本製紙株式会社
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Application filed by 日本製紙株式会社 filed Critical 日本製紙株式会社
Priority to JP2018545779A priority Critical patent/JPWO2018074604A1/en
Publication of WO2018074604A1 publication Critical patent/WO2018074604A1/en

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H19/00—Coated paper; Coating material
    • D21H19/36—Coatings with pigments
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/18—Paper- or board-based structures for surface covering

Definitions

  • the present invention relates to a coated white paperboard having a contour coating layer.
  • White paperboard is often used as a container for foodstuffs, pharmaceuticals, cosmetics, and the like, especially for coated whiteboard paper, there is an increasing demand for improvement in appearance and printability from the viewpoint of visualization.
  • Coated white paperboard is processed by stamping after printing, but the paper often overlaps in the post-processing process, etc., and so-called ink scuffing occurs that causes the prints to rub and contaminate the printing surface. Is a problem.
  • a method of protecting the printed surface by varnishing is generally used, but there is a problem that work efficiency deteriorates due to an increase in the number of processes. Therefore, there is a demand for measures that do not increase the work load at the printing shop.
  • Patent Documents 1 and 2 a coating layer containing a plate-like pigment having a specific average particle diameter in a proportion exceeding 65% by weight with respect to the total pigment is applied by blade coating.
  • White paperboard provided is proposed.
  • white unevenness is an example of quality required for appearance.
  • White unevenness is defined as the standard deviation of whiteness in a minute area. Even if the whiteness is high, if the white unevenness is inferior, the surface feel is poor, and the unevenness is further emphasized particularly in the halftone dot portion of the printed material, so that the value as the printed material is inferior. When the difference between the whiteness of the base paper and the whiteness of the coating layer is large, the whiteness unevenness is particularly remarkable when the coating unevenness of the coating layer is inferior.
  • the opacity of the pigment coating layer provided by the curtain coating method is set to 50% or more, and the outermost layer of the multilayer base paper and its direct A method of increasing the whiteness difference of the lower layer to more than 12% or a method of adding a black dye to the coating pigment to make the whiteness of the base paper and the whiteness of the coating layer within 6% are proposed. (Patent Documents 3 and 4).
  • an object of the present invention is to provide a coated white paperboard with reduced whiteness unevenness with reduced ink rubbing.
  • a coated white board with less white unevenness with reduced ink rubbing can be provided.
  • X to Y includes its end values, that is, X and Y.
  • X or Y means either X or Y, or both.
  • Coated white paperboard (1) base paper
  • the base paper used in the present invention is not limited as long as it is generally used in the field of coated white paperboard, but it is preferable that used paper pulp or chemical pulp is blended.
  • Used paper pulp includes high-quality paper, medium-quality paper, newspapers, leaflets, magazines, and other sorted waste paper, corrugated wastepaper, and undeinked wastepaper pulp made from unsorted wastepaper mixed with these.
  • Kraft pulp, sulfite pulp, etc. can be used as chemical pulp.
  • Pulp other than waste paper pulp or chemical pulp is not particularly limited, and mechanical pulp such as thermomechanical pulp and pressurized groundwood pulp; semi-chemical pulp such as chemical thermomechanical pulp can be used.
  • the amount of the used paper pulp is 50% by weight or more, preferably 80% by weight or more based on the total pulp.
  • the base paper is preferably a multi-layer base paper.
  • the outermost layer on the side on which the pigment is applied is referred to as the surface layer
  • the second layer from the coated surface toward the opposite side is referred to as the lower layer
  • the other layers are referred to as other layers.
  • the outermost surface is also called the back layer
  • the middle layer is also called the layer which comprises an intermediate
  • the base paper with three or more layers
  • a plurality of layers can be stacked.
  • the chemical pulp is used as the surface pulp
  • the whiteness and white unevenness are excellent, and when the used paper pulp is used, it is advantageous in terms of cost, but is not limited thereto.
  • the base paper can be uniformly coated with the contour coating layer, and therefore, the coated white paperboard with reduced whiteness unevenness Can be obtained.
  • the lower layer and the middle layer are mainly composed of waste paper pulp.
  • ⁇ Filler may be added to the base paper.
  • Such filler is not particularly limited, for example, diatomaceous earth, talc, kaolin, calcined kaolin, delaminated kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, Amorphous silica, calcium sulfite, gypsum, white carbon, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, paper sludge, inorganic fillers such as regenerated inorganic particles from deinking floss, urea-formalin resin, Organic fillers such as polystyrene resin, vinyl chloride resin, melamine resin, phenol resin, and plastic hollow particles, and fillers contained in waste paper and broke can be used alone or in combination of two or more.
  • the content of the filler in the base paper is not limited and is appropriately selected.
  • coagulation aids paper strength enhancers, tinting dyes or pigments, and sizing agents can be used in the base paper layer according to the desired quality.
  • a yield improver in order to improve the operability at the time of papermaking, a yield improver, a drainage improver, and an antifoaming agent can be used as appropriate.
  • the paper making method of the base paper is not particularly limited, and a long paper machine including a top wire, an on-top former, a gap former, a round paper machine, a paperboard machine using both a long paper machine and a round paper machine, It can be performed using a Yankee dryer machine, a hybrid type paper machine combining these, or the like, and two or more layers may be combined to form a base paper.
  • the pH during papermaking may be acidic, neutral or alkaline, but neutral or alkaline is preferred.
  • the paper making speed is not particularly limited.
  • the basis weight of the base paper is preferably 150 to 700 g / m 2 .
  • the base paper when the coated paper is produced according to the present invention, the base paper may be smoothed in advance by a soft calendar, a chilled calendar or the like before the coating process. According to the contour coating method of the present invention, even if the base paper is pre-smoothed, the fine unevenness on the surface of the base paper can be reflected in the unevenness of the pigment coating layer, and thus obtained by the present invention.
  • the coated white paperboard is a coated whiteboard paper that has less ink rub than the contact-type coating method even if the base paper is smoothed.
  • the coated white paperboard of the present invention comprises a pigment coating layer.
  • the pigment coating layer is a coating layer containing a so-called white pigment.
  • the number of the pigment coating layers is not limited and may be a single layer or two layers, three layers, or four layers. The effects of the present invention can be obtained, but in consideration of concealability, cost, etc., two layers or three layers It is preferable that there are two layers.
  • Known pigments can be used. Specifically, heavy calcium carbonate, light calcium carbonate, diatomaceous earth, talc, kaolin, calcined kaolin, delaminated kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate From barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, calcium sulfite, gypsum, white carbon, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, paper sludge, deinking floss
  • Inorganic fillers such as regenerated inorganic particles, organic fillers such as urea-formalin resin, polystyrene resin, vinyl chloride resin, melamine resin, phenol resin, and plastic micro hollow particles can be used.
  • the total amount of kaolin or clay in the total amount of pigment of 100 parts by weight is preferably 25 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 15 parts by weight or less. That is, in the total amount of pigment, the total amount of kaolin or clay is preferably 25% by weight or less, more preferably 20% by weight or less, and further preferably 15% by weight or less.
  • the total amount of pigment is the total amount of pigment contained in each pigment coating layer.
  • Kaolin or clay has a high aspect ratio and is sometimes referred to as a high aspect ratio pigment. Examples of the high aspect ratio pigment include plate pigments such as talc, clay, kaolin, calcined kaolin, and delaminated kaolin.
  • the pigment coating layer containing a lot of high aspect ratio pigments may crack
  • the blend ratio of high aspect ratio pigments, especially kaolin or clay is also used to suppress cracking of the pigment coating layer.
  • it is low.
  • calcium carbonate with high whiteness is preferably used, and light calcium carbonate or heavy calcium carbonate can be used as calcium carbonate.
  • the amount of kaolin or clay is the same in the surface layer and the lower layer. It may be different or different.
  • the amount of kaolin or clay in the surface layer can be larger than that of the lower layer, for example, the proportion of kaolin or clay in the surface layer is 30% by weight or less and the proportion of kaolin or clay in the lower layer is 5% by weight or less.
  • the pigment coating layer may contain a known adhesive.
  • the adhesive those conventionally used for coated paper can be used.
  • adhesives include styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, and other copolymers, polyvinyl alcohol, maleic anhydride copolymer Synthetic adhesives such as coalescence and acrylic acid / methyl methacrylate copolymers; proteins such as casein, soy protein, synthetic protein; oxidized starch, positive starch, urea phosphated starch, enzyme-modified starch, hydroxyethyl ether Examples thereof include ordinary coated paper adhesives such as etherified starch such as modified starch, starches such as dextrin; cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, and hydroxymethylcellulose.
  • One or more types of adhesives can be appropriately selected and used,
  • the blending ratio of the pigment and the adhesive is appropriately adjusted within a range where a desired pigment coating solution can be obtained.
  • the solid content ratio is preferably 5 to 30 parts by weight, more preferably 8 to 20 parts by weight with respect to 100 parts by weight of the pigment.
  • the amount of the adhesive is less than 5 parts by weight, the coating layer strength is weakened, and paper dust is generated or the printing strength is inferior.
  • the amount of the adhesive is more than 30 parts by weight, the gap between the pigment particles in the coating layer is filled with the adhesive and the light scattering property of the coating layer is inferior. May be inferior, cost may increase, and the like.
  • a dispersant in addition to the pigment and the adhesive, if necessary, a dispersant, a viscosity improver, a water retention agent, an antifoaming agent, a water resistant agent, a fluorescent dye, Various auxiliaries blended into ordinary coated paper pigments such as colored dyes, colored pigments, surfactants, pH adjusters, cationic resins, anionic resins, ultraviolet absorbers and metal salts can be used as appropriate.
  • the total amount of the pigment coating layer is not limited, but is preferably about 10 to 35 g / m 2 per side, and more preferably about 15 to 30 g / m 2 .
  • the pigment coating layer is a contour coating layer.
  • the contour coating layer is a uniform coating layer provided so as to trace the contour of the base paper, and is a coating layer that substantially reproduces the irregularities on the surface of the base paper.
  • the contour coating layer is formed by a contour coating method coating apparatus, and can be formed by a coating device such as a curtain coating method, an air knife coating method, a spray coating method, or a contact type contour coating method. It is not limited to these.
  • the curtain coating in which the coating layer is provided by the curtain coating method will be described in detail later. When a plurality of pigment coating layers are present, all the pigment coating layers are preferably contour coating layers.
  • the coated white paperboard of the present invention is a clear coating layer comprising various adhesives and various auxiliaries used for the above-mentioned pigment coating layer between the base paper layer and the pigment coating layer. You may have. However, from the viewpoint of reflecting the unevenness of the surface of the base paper layer on the surface of the pigment coating layer, when a clear coating layer is provided, the coating amount is preferably small, specifically about 0.1 to 5 g / m 2. It is preferable that The clear coating layer need not be a contour coating layer.
  • the coated white paperboard of the present invention may have a pigment coating layer by contour coating on one side, but a clear coating layer on the other side (also referred to as “back side” for convenience).
  • a pigment coating layer may be provided.
  • the back coating layer is, as necessary, known pigments and binders, dispersants, viscosity improvers, water retention agents, antifoaming agents, water resistance agents, fluorescent dyes, colored dyes, colored pigments, surfactants, It may contain a pH adjuster, a cationic resin, an anionic resin, an ultraviolet absorber, a metal salt, and the like.
  • the clear or pigment coating layer on the back surface does not need to be contour coating, and may be provided by a known method such as blade coating.
  • the coating amount is not particularly limited, but is generally 0.1 to 5 g / m 2 in terms of solid content on one side.
  • the coated white paperboard of the present invention has appropriate smoothness reflecting irregularities at the base paper level.
  • Smoothness is an index of the degree of unevenness of the surface, depending on the surface distribution of the coating layer obtained by Oken-type smoothness, image processing using PPS roughness, KEYENCE one-shot 3D measurement microscope, etc. Although measured, it is not limited to these. If the smoothness is too high, the contact area between the papers becomes large and the ink rubbing deteriorates or the glossiness increases too much. Therefore, the ink rubbing reduction effect of the present invention and an appropriate white paper glossiness are obtained. It becomes difficult. On the other hand, if the smoothness is too low, there is a possibility that the printing surface feeling and the transportability are deteriorated.
  • the coated white paperboard of the present invention has a PPS roughness of more than 1.3 ⁇ m and not more than 3.0 ⁇ m under the condition of a clamp pressure of 2000 kPa.
  • the upper limit is preferably 2.5 ⁇ m or less, more preferably 2.3 ⁇ m or less.
  • the PPS roughness is an index representing the roughness of the surface of the coated white paperboard measured according to ISO8791.
  • the coated white paperboard having the PPS roughness in the above range reflects the unevenness of the fiber level on the surface of the base paper, thereby reducing ink rub. If the PPS roughness is 1.3 ⁇ m or less, the smoothness becomes high and ink scuffing may occur.
  • the PPS roughness is preferably more than 1.3 ⁇ m and 2.3 ⁇ m or less.
  • the PPS roughness of the base paper under the condition of 2000 kPa is 5 to 15 ⁇ m.
  • the upper limit is preferably 14 ⁇ m or less, more preferably 12 ⁇ m or less, and the lower limit is preferably 6 ⁇ m or more, more preferably 8 ⁇ m or more.
  • the coated white board of the present invention is provided with a pigment coating layer by contour coating, the unevenness of the base paper is reflected in the unevenness of the coated white board, and ink rubbing can be reduced. Therefore, when the PPS roughness of the base paper is within the above range, it is possible to obtain a coated white paperboard in which sufficient irregularities are formed on the surface of the coated white paperboard after the contour coating layer is provided, and ink rubbing is reduced. it can.
  • the D50 value of the height distribution of the coating layer surface obtained by image processing is 5 or more and 25% or less. Is preferred.
  • the D50 is also an index representing the surface roughness of the coated white paperboard, and if the D50 is within this range, ink scuffing is reduced.
  • An apparatus for obtaining the height distribution on the surface of the coating layer by image processing includes, for example, a one-shot 3D measurement microscope (trade name: VR-3100) manufactured by KEYENCE Corporation.
  • the coated white paperboard of the present invention preferably has a DAV2 value of 50 or less.
  • the DAV2 value is an index representing the feeling of haze on the coated paper surface measured using an appearance analyzer manufactured by DuPont. The lower the value, the lower the haze.
  • the DAV2 value is higher than 50, the feeling is somewhat high, and when used as a container such as a box, there may be a problem from the viewpoint of appearance.
  • the coated white paperboard of the present invention preferably has a white paper gloss of 45 to 60%.
  • the white paper glossiness of the present invention is an index of glossiness measured according to JIS-P8142.
  • the whiteness of the coated white board of the present invention is preferably 75 to 85%, and the whiteness of the base paper is preferably 60 to 75%.
  • the whiteness of the base paper is within the above range, a coated white board with excellent whiteness can be obtained.
  • Engineered white paperboard can be obtained.
  • the whiteness is measured in accordance with JIS P8148 “Paper, paperboard and pulp—Method of measuring ISO whiteness (diffuse blue light reflectance)”.
  • Basis weight of the coated white paperboard of the present invention is not particularly limited, but is preferably about 150 to 800 g / m 2 .
  • the coated white paperboard of the present invention has excellent ink rub resistance.
  • the reason for this is not limited, but the coated white paperboard of the present invention is provided with the entire pigment coating layer by contour coating, so it is different from the coating layer provided only by the contact coating method such as blade coating.
  • the unevenness on the surface of the coated white paperboard is also reflected on the surface of the coated layer. Therefore, it is considered that the contact area between the papers when the papers are stacked is small, and even if the surface is rubbed against the print part, it is difficult to scrape the print part on the surface.
  • the contour coating layer is excellent in layer uniformity, white unevenness can also be reduced.
  • the coated white paperboard of the present invention is preferably produced by providing two or more pigment coating layers on a base paper using a contour coating type coating apparatus.
  • the contour coating is a coating method in which a coating layer having a uniform film thickness along the unevenness of a base material such as a base paper is provided.
  • the contour coating method forms a coating layer that reflects the unevenness of the fiber level, so the resulting coated paper has a high level of glossiness compared to the blade coating method.
  • Features such as low Examples of the coating method of the contour coating method include curtain coating, air knife coating, spray coating, various contact type contour coating, etc., but the contour coating of the present invention may be curtain coating. preferable.
  • curtain coating is a pre-measuring method, in which a film is formed by flowing a coating liquid whose flow rate is adjusted according to the coating amount into a curtain shape, and the base paper is passed through the film.
  • This is a coating method in which a coating layer is provided on a base paper. Therefore, the unevenness on the base paper can be easily reproduced on the surface of the coating layer.
  • curtain coating is not scraped off by a blade, and the coating layer formed as a curtain film is placed on the base paper as it is, so that there are many voids in the coating layer, which is preferable in terms of light scattering and whiteness.
  • a well-known apparatus can be used for curtain coating.
  • What is known as the shape of the curtain coating apparatus is a slot type curtain coating apparatus that directly forms a curtain film by discharging the coating liquid downward from the die, and discharging the coating liquid upward from the die,
  • a slide-type curtain coating apparatus that flows while forming a coating liquid film on a slope on a die, and then forms a curtain film by free-falling after leaving the die.
  • any apparatus may be used, but it is preferable to apply multilayer coating by simultaneously forming two or more curtain films using a slot mold.
  • the coating speed is not particularly limited, and can be about 100 to 600 m / min.
  • the solid content concentration of the coating liquid is preferably 58% by weight or more, and more preferably 62% by weight or more.
  • the upper limit of the solid content concentration is not particularly limited, but is preferably 75% by weight or less and more preferably 70% by weight or less in consideration of liquid feeding properties.
  • Example 1 (Base paper 1) Using LBKP 100% by weight pulp, surface layer of 33g / m 2 basis weight, deinked waste paper pulp 80% by weight, non-deinked magazine waste paper pulp 20% by weight, basis weight 36g / m 2 surface layer, Made from 100% by weight of non-black magazine paper pulp, the 4th to 7th layers are made using the same middle and middle layer pulps with a basis weight of 44g / m 2 and combined, pressed and dried. A coated white paperboard base paper having a basis weight of 294 g / m 2 was obtained.
  • the outermost layer on the side on which the pigment is applied is referred to as the surface layer
  • the second layer from the coated surface to the opposite side is referred to as the lower layer
  • the outermost surface is referred to as the back layer
  • the other layers are referred to as the middle layer.
  • the coating liquid B was the outermost layer on one side of the base paper 1 and dried.
  • the coating liquid A layer was a pre-coating layer
  • the coating liquid B layer was a top coating layer.
  • Amount of coating is pre-coated layer weight after drying of 20 g / m 2
  • the top coating layer is 5 g / m 2
  • the basis weight of the coated white paperboard was 316.3 g / m 2.
  • the coating speed was 300 m / min, the same as the papermaking speed, since it was performed consistently with the papermaking by on-machine.
  • the coated white paperboard obtained was calendered to obtain a coated white paperboard.
  • the processing speed was 300 m / min, which was the same as the papermaking speed and the coating speed, because it was performed consistently with the papermaking and coating by on-machine.
  • Example 2 A coated white board was obtained and evaluated in the same manner as in Example 1 except that the coating liquid B was applied to one side of the base paper 1 with a slot type curtain coating apparatus.
  • the coating amount was 25 g / m 2 by weight after drying, and the basis weight of the coated white paperboard was 316.5 g / m 2 .
  • 5 parts by weight of urea phosphate starch with respect to 100 parts by weight of pigment.
  • 14.5 parts by weight of styrene / butadiene copolymer latex was added.
  • water was added to adjust the B-type viscosity at 30 ° C. and 60 rpm to 1000 mPa ⁇ s to obtain a coating liquid D having a solid content concentration of 62% by weight and a static surface tension of 30 mN / m.
  • Example 1 the base paper 1 was adjusted to have a basis weight distribution of 295 g / m 2 by adjusting the basis weight distribution of the fourth to seventh layers, and the coating liquid C was applied as a pre-coating layer by bar coating. After passing through the drying step, the coating liquid D was applied as a top coating layer by a vent blade coating method. Amount of coating is pre-coated layer weight after drying of 8 g / m 2, the top coating layer is 12 g / m 2, the basis weight of the coated white paperboard was 315.1g / m 2. A coated white paperboard was obtained in the same manner as in Example 1 except for the configuration of the coating layer.
  • Example 2 A coated white paperboard was obtained and evaluated in the same manner as in Example 1 except that the calendar process was not performed.
  • the basis weight of the coated white paperboard was 318.5g / m 2.
  • the coating liquid D was applied onto the base paper used in Comparative Example 1 by a vent blade coating method to form a pre-coating layer.
  • the coating liquids A and B were simultaneously applied to the coating liquid B by a slot type curtain coating apparatus so that the coating liquid B was the outermost layer, and dried.
  • Amount of coating is pre-coated layer is 10 g / m 2 by weight of the dry basis weight of the intermediate coating layer 10 g / m 2
  • the top coating layer is 5 g / m 2 coated white paperboard 317 0.9 g / m 2 .
  • the coated white paperboard thus prepared was evaluated as follows. The results are shown in Table 1.
  • Basis weight Measured according to JIS P 8124.
  • Paper thickness Measured according to JIS P 8118.
  • Density Determined from basis weight and paper thickness according to JIS P 8118.
  • Oken smoothness measured according to JIS P 8155.
  • PPS roughness PPS surface roughness measured according to ISO8791. Measured with soft backing.
  • Glossiness of blank paper measured based on JIS-P8142.
  • Whiteness Measured according to JIS P8148.
  • Ink rubbing Ink density of solid part at a printing speed of 8000 sheets / hr using offset sheet-fed ink (NEX-M manufactured by Toyo Ink) with an offset sheet-fed printing machine (4 colors) manufactured by Roland After printing so that the ink becomes 1.80, the humidity is adjusted for 24 hours according to JIS P8111, and a load of 500 gf is applied by the Gakushin type friction fastness tester so that the black solid printing part fits the blank paper part.
  • the ink which rubbed once and transferred to the white paper portion was visually evaluated as ink rubbing.
  • DAV2 The appearance feeling of the coated paper was evaluated using an appearance analyzer manufactured by DuPont. The larger the value is, the more slightly the surface of the coated paper is, and the lower the blank paper feel. (10) Print surface feeling Evaluated visually.
  • the coated white paperboard of the present invention has excellent ink rub resistance.

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Abstract

Provided is a coated white paperboard provided with a base paper and two or more pigment coating layers, wherein the pigment coating layer is a contour coating layer, and the PPS roughness under the condition that a clamping pressure is 200 kPa is greater than 1.3 µm and equal to or less than 3.0 µm. The coated white paperboard has reduced ink friction and low white unevenness.

Description

塗工白板紙Coated white paperboard
　本発明は輪郭塗工層を有する塗工白板紙に関する。 The present invention relates to a coated white paperboard having a contour coating layer.
　白板紙は、食料品や医薬品、化粧品などの容器として使用されることが多く、特に塗工白板紙においては、視覚化の面から外観性や印刷適性等の向上に対する要求が高まっている。塗工白板紙は印刷後に打ち抜き等の加工を行うが、後加工工程等において紙同士が重なりあうことが多いため、その際に印字が擦れて印刷面が汚染されるいわゆるインキ擦れが発生することが問題となっている。このようなインキ擦れを解消するために、一般的には印刷面をニス引きなどによって保護する手法がとられているが、工程が増えることにより作業効率が悪化してしまうなどの問題があるため、印刷所での作業負担の増えない対策が求められている。これに対して、これまでに例えば特許文献１および２には、特定の平均粒子径を有する板状顔料を全顔料に対して６５重量％を超える割合で含有する塗工層をブレード塗工して設けた白板紙が提案されている。 White paperboard is often used as a container for foodstuffs, pharmaceuticals, cosmetics, and the like, especially for coated whiteboard paper, there is an increasing demand for improvement in appearance and printability from the viewpoint of visualization. Coated white paperboard is processed by stamping after printing, but the paper often overlaps in the post-processing process, etc., and so-called ink scuffing occurs that causes the prints to rub and contaminate the printing surface. Is a problem. In order to eliminate such ink rubbing, a method of protecting the printed surface by varnishing is generally used, but there is a problem that work efficiency deteriorates due to an increase in the number of processes. Therefore, there is a demand for measures that do not increase the work load at the printing shop. On the other hand, for example, in Patent Documents 1 and 2, a coating layer containing a plate-like pigment having a specific average particle diameter in a proportion exceeding 65% by weight with respect to the total pigment is applied by blade coating. White paperboard provided is proposed.
　また、外観性で求められる品質としては白色ムラが挙げられる。白色ムラとは、微小面積における白色度の標準偏差と定義される。白色度が高くても白色ムラが劣る場合、面感が悪く、また印刷物の特に網点部においてムラがさらに強調されるため、印刷物としての価値が劣る。白色ムラは、原紙の白色度と塗工層の白色度の差が大きい場合、塗工層の塗工ムラが劣ると特に顕著となる。そこで、塗工層と原紙の白色度を近づけて白色ムラを低減させるために、カーテン塗工方式で設けられた顔料塗工層の不透明度を５０％以上にし、多層原紙の最表層とその直下層の白色度差を１２％より大きくする方法や、塗工顔料に黒染料を配合して、原紙の白色度と塗工層の白色度を６％以内にするなどの方法が提案されている（特許文献３、４）。 Also, white unevenness is an example of quality required for appearance. White unevenness is defined as the standard deviation of whiteness in a minute area. Even if the whiteness is high, if the white unevenness is inferior, the surface feel is poor, and the unevenness is further emphasized particularly in the halftone dot portion of the printed material, so that the value as the printed material is inferior. When the difference between the whiteness of the base paper and the whiteness of the coating layer is large, the whiteness unevenness is particularly remarkable when the coating unevenness of the coating layer is inferior. Therefore, in order to reduce whiteness by bringing the whiteness of the coating layer and the base paper closer, the opacity of the pigment coating layer provided by the curtain coating method is set to 50% or more, and the outermost layer of the multilayer base paper and its direct A method of increasing the whiteness difference of the lower layer to more than 12% or a method of adding a black dye to the coating pigment to make the whiteness of the base paper and the whiteness of the coating layer within 6% are proposed. (Patent Documents 3 and 4).
　この他にも、上述の古紙パルプ多配合の紙を使用しながら、効率よくチリを目立たなくし、白色度や印刷適正を向上させる技術として、表面に塗被する塗工量を多くする、隠蔽性の高い二酸化チタンや構造化カオリン、プラスチックピグメント等の有機顔料を多量に配合する方法が提案されている（特許文献５、６）。 In addition to this, while using the above-mentioned waste paper pulp multi-blend paper, as a technology to make the dust inconspicuous efficiently and improve the whiteness and printability, the coating amount to be applied to the surface is increased, the concealability A method of blending a large amount of organic pigments such as high-titanium dioxide, structured kaolin, and plastic pigment has been proposed (Patent Documents 5 and 6).
特開２００８－９５２７４号公報JP 2008-95274 A 特開２０１１－１１７１２２号公報JP 2011-117122 A 特開２００９－４１１３１号公報JP 2009-41131 A 特開平１－９７２９５号公報JP-A-1-97295 特開平６－１６６９９１号公報JP-A-6-166991 特開２００３－３０６８９２号公報JP 2003-306882 A
　従来、インキ擦れを解消するために塗工層の顔料形状を最適化することが試みられてきたが、インキ擦れの低減度合いは未だ十分満足するレベルではない。また、白色ムラに関しても、高価な資材や設備を使用する必要があったり、白色度の低減を伴うなど課題があった。かかる事情を鑑み、本発明はインキ擦れを低減させた白色ムラの少ない塗工白板紙を提供することを課題とする。 Conventionally, attempts have been made to optimize the pigment shape of the coating layer in order to eliminate ink rubbing, but the degree of ink rubbing reduction is not yet sufficiently satisfactory. In addition, there are problems with white unevenness, such as the need to use expensive materials and equipment, and a reduction in whiteness. In view of such circumstances, an object of the present invention is to provide a coated white paperboard with reduced whiteness unevenness with reduced ink rubbing.
　発明者らは、輪郭塗工による均一な顔料塗工層を設け、板紙表面に繊維レベルの凹凸を形成することで、前記課題が解決できることを見出した。すなわち、前記課題は以下の本発明により解決される。
（１）原紙および顔料塗工層を備える塗工白板紙であって、
　前記顔料塗工層が輪郭塗工層であり、
　クランプ圧２０００ｋＰａの条件におけるＰＰＳラフネスが１．３μｍ超３．０μｍ以下である、塗工白板紙。
（２）前記顔料塗工層中の顔料の総量１００重量部中、カオリンまたはクレーの合計量が２５重量部以下である、（１）記載の塗工白板紙。
（３）前記輪郭塗工層がカーテン塗工層である、（１）または（２）に記載の塗工白板紙。
（４）アピアランスアナライザーによって測定されるＤＡＶ２値が５０以下である、（１）～（３）のいずれかに記載の塗工白板紙。
（５）白紙光沢度が４５～６０％である、（１）～（４）のいずれかに記載の塗工白板紙。 The inventors have found that the above problem can be solved by providing a uniform pigment coating layer by contour coating and forming fiber level irregularities on the paperboard surface. That is, the said subject is solved by the following this invention.
(1) A coated white board having a base paper and a pigment coating layer,
The pigment coating layer is a contour coating layer,
Coated white paperboard having a PPS roughness of more than 1.3 μm and not more than 3.0 μm under the condition of a clamping pressure of 2000 kPa.
(2) The coated white paperboard according to (1), wherein the total amount of kaolin or clay is 25 parts by weight or less in 100 parts by weight of the total amount of pigment in the pigment coating layer.
(3) The coated white paperboard according to (1) or (2), wherein the contour coating layer is a curtain coating layer.
(4) The coated white paperboard according to any one of (1) to (3), wherein the DAV2 value measured by an appearance analyzer is 50 or less.
(5) The coated white paperboard according to any one of (1) to (4), wherein the glossiness of the white paper is 45 to 60%.
　本発明によりインキ擦れを低減させた白色ムラの少ない塗工白板紙を提供できる。 According to the present invention, a coated white board with less white unevenness with reduced ink rubbing can be provided.
　以下、本発明を詳細に説明する。本発明において「Ｘ～Ｙ」はその端値、すなわちＸおよびＹを含む。「ＸまたはＹ」は、Ｘ、Ｙのいずれか、あるいはその両方を意味する。 Hereinafter, the present invention will be described in detail. In the present invention, “X to Y” includes its end values, that is, X and Y. “X or Y” means either X or Y, or both.
１．塗工白板紙
（１）原紙
　本発明で使用される原紙は、一般に塗工白板紙の分野で使用されているものであれば限定されないが、古紙パルプまたは化学パルプが配合されていることが好ましい。古紙パルプとしては、上質紙、中質紙、新聞紙、チラシ、雑誌などの選別古紙、段ボール古紙やこれらが混合している無選別古紙を原料とする脱墨古紙パルプまたは脱墨しない古紙パルプを使用でき、化学パルプとしてはクラフトパルプ、亜硫酸パルプなどを使用できる。古紙パルプまたは化学パルプ以外のパルプは特に制限されず、サーモメカニカルパルプ、加圧砕木パルプなどの機械パルプ；ケミカルサーモメカニカルパルプなどの半化学パルプが使用できる。古紙パルプの配合量は、全パルプ中５０重量％以上、好ましくは８０重量％以上とできる。 1. Coated white paperboard (1) base paper The base paper used in the present invention is not limited as long as it is generally used in the field of coated white paperboard, but it is preferable that used paper pulp or chemical pulp is blended. . Used paper pulp includes high-quality paper, medium-quality paper, newspapers, leaflets, magazines, and other sorted waste paper, corrugated wastepaper, and undeinked wastepaper pulp made from unsorted wastepaper mixed with these. Kraft pulp, sulfite pulp, etc. can be used as chemical pulp. Pulp other than waste paper pulp or chemical pulp is not particularly limited, and mechanical pulp such as thermomechanical pulp and pressurized groundwood pulp; semi-chemical pulp such as chemical thermomechanical pulp can be used. The amount of the used paper pulp is 50% by weight or more, preferably 80% by weight or more based on the total pulp.
　原紙は多層抄き原紙であることが好ましい。本発明では、多層抄きの原紙において、顔料を塗工する側の最表層を表層、塗工面から反対側に向かって２層目を表下層、それ以外を他層という。他層のうち、最裏面を裏層、それ以外を中層ともいう。また、中層を構成する層を、塗工する面から数えて３層目、４層目ということもある。例えば、３層抄き以上の原紙の場合、中層に白色度の低いパルプを用いて、表層、裏層にそれより白色度が高いパルプを用いることもできるし、すべての層のパルプを同じものとして複数層重ねることもできる。表層のパルプは化学パルプを用いた場合は白色度や白色ムラが優れたものとなり、古紙パルプを用いた場合はコストの面で優位であるが、これらに限定されない。本発明によれば、例え低白色度の古紙パルプを多く用いた原紙を使用したとしても、輪郭塗工層により原紙を均一に被覆することができるため、白色ムラが低減された塗工白板紙を得ることができる。表下層および中層は主として古紙パルプで構成されることが好ましい。特に中層には古紙パルプを１００重量％使用することが好ましく、そのうち８０重量％以上を脱墨しない古紙パルプとしてもよい。 The base paper is preferably a multi-layer base paper. In the present invention, in the multi-layer paper, the outermost layer on the side on which the pigment is applied is referred to as the surface layer, the second layer from the coated surface toward the opposite side is referred to as the lower layer, and the other layers are referred to as other layers. Of the other layers, the outermost surface is also called the back layer, and the other is also called the middle layer. Moreover, the layer which comprises an intermediate | middle layer may be called the 3rd layer and the 4th layer from the surface to apply. For example, in the case of base paper with three or more layers, you can use pulp with low whiteness for the middle layer and pulp with higher whiteness for the front and back layers, or the same pulp for all layers A plurality of layers can be stacked. When the chemical pulp is used as the surface pulp, the whiteness and white unevenness are excellent, and when the used paper pulp is used, it is advantageous in terms of cost, but is not limited thereto. According to the present invention, even if a base paper using a large amount of waste paper pulp with low whiteness is used, the base paper can be uniformly coated with the contour coating layer, and therefore, the coated white paperboard with reduced whiteness unevenness Can be obtained. It is preferable that the lower layer and the middle layer are mainly composed of waste paper pulp. In particular, it is preferable to use 100% by weight of waste paper pulp for the middle layer, and 80% by weight or more of the waste paper pulp may be used as non-deinked waste paper pulp.
　原紙には填料が内添されてもよい。かかる填料としては特に限定されないが、例えば、ケイソウ土、タルク、カオリン、焼成カオリン、デラミネーティッドカオリン、重質炭酸カルシウム、軽質炭酸カルシウム、炭酸マグネシウム、炭酸バリウム、二酸化チタン、酸化亜鉛、酸化ケイ素、非晶質シリカ、亜硫酸カルシウム、石膏、ホワイトカーボン、水酸化アルミニウム、水酸化カルシウム、水酸化マグネシウム、水酸化亜鉛、製紙スラッジ、脱墨フロスからの再生無機粒子等の無機填料、尿素―ホルマリン樹脂、ポリスチレン樹脂、塩化ビニル樹脂、メラミン樹脂、フェノール樹脂、プラスチック微小中空粒子などの有機填料、さらには古紙やブロークに含まれている填料を、単独もしくは適宜２種類以上組み合わせて使用できる。原紙の上記填料の含有割合（原紙灰分）は限定されず適宜選択される。原紙灰分が低いほど剛度が向上し、原紙灰分が高い程柔軟性が向上するため、例えば剛度の高い原紙を得たい場合は１０重量％未満とし、しなやかな原紙を得たい場合は１０重量％以上とすることができる。 ∙ Filler may be added to the base paper. Such filler is not particularly limited, for example, diatomaceous earth, talc, kaolin, calcined kaolin, delaminated kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, Amorphous silica, calcium sulfite, gypsum, white carbon, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, paper sludge, inorganic fillers such as regenerated inorganic particles from deinking floss, urea-formalin resin, Organic fillers such as polystyrene resin, vinyl chloride resin, melamine resin, phenol resin, and plastic hollow particles, and fillers contained in waste paper and broke can be used alone or in combination of two or more. The content of the filler in the base paper (base paper ash content) is not limited and is appropriately selected. The lower the base paper ash content, the higher the stiffness, and the higher the base paper ash content, the more flexible. For example, if you want to obtain a base paper with high rigidity, make it less than 10% by weight. It can be.
　また、目的とする品質に合わせて原紙層で凝集助剤、紙力増強剤、色味付け染料または顔料、サイズ剤を使用できる。また、抄紙時の操業性を向上させるために、歩留り向上剤、濾水向上剤、消泡剤を適宜用いることができる。 Also, coagulation aids, paper strength enhancers, tinting dyes or pigments, and sizing agents can be used in the base paper layer according to the desired quality. Moreover, in order to improve the operability at the time of papermaking, a yield improver, a drainage improver, and an antifoaming agent can be used as appropriate.
　原紙の抄紙方法は特に限定されず、トップワイヤー等を含む長網抄紙機、オントップフォーマー、ギャップフォーマー、丸網抄紙機、長網抄紙機と丸網抄紙機を併用した板紙抄紙機、ヤンキードライヤーマシン、これらを組み合わせたハイブリッド型抄紙機等を用いて行うことができ、２層以上を抄き合わせて原紙としてもよい。抄紙時のｐＨは、酸性、中性、アルカリ性のいずれでもよいが、中性またはアルカリ性が好ましい。抄紙速度は、特に限定されない。原紙の坪量は１５０～７００ｇ／ｍ２であることが好ましい。また、本発明により塗工紙を製造する場合は、原紙をソフトキャレンダ、チルドカレンダなどにより、塗工工程の前に、予め平滑化しておいてもよい。本発明の輪郭塗工方式によれば、例え原紙に予め平滑化処理を施したとしても、原紙表面の微細な凹凸を顔料塗工層の凹凸に反映させることができるため、本発明で得られる塗工白板紙は、たとえ原紙に平滑化処理を行ったとしても接触型塗工方式よりもインキ擦れを低減した塗工白板紙となる。 The paper making method of the base paper is not particularly limited, and a long paper machine including a top wire, an on-top former, a gap former, a round paper machine, a paperboard machine using both a long paper machine and a round paper machine, It can be performed using a Yankee dryer machine, a hybrid type paper machine combining these, or the like, and two or more layers may be combined to form a base paper. The pH during papermaking may be acidic, neutral or alkaline, but neutral or alkaline is preferred. The paper making speed is not particularly limited. The basis weight of the base paper is preferably 150 to 700 g / m 2 . Further, when the coated paper is produced according to the present invention, the base paper may be smoothed in advance by a soft calendar, a chilled calendar or the like before the coating process. According to the contour coating method of the present invention, even if the base paper is pre-smoothed, the fine unevenness on the surface of the base paper can be reflected in the unevenness of the pigment coating layer, and thus obtained by the present invention. The coated white paperboard is a coated whiteboard paper that has less ink rub than the contact-type coating method even if the base paper is smoothed.
（２）顔料塗工層
　本発明の塗工白板紙は顔料塗工層を備える。顔料塗工層とはいわゆる白色顔料を含む塗工層である。顔料塗工層の数は限定されず、単層でもよく、２層、３層、４層としても本発明の効果を得ることができるが、隠蔽性やコスト等を考慮すると２層または３層であることが好ましく、より好ましくは２層である。 (2) Pigment coating layer The coated white paperboard of the present invention comprises a pigment coating layer. The pigment coating layer is a coating layer containing a so-called white pigment. The number of the pigment coating layers is not limited and may be a single layer or two layers, three layers, or four layers. The effects of the present invention can be obtained, but in consideration of concealability, cost, etc., two layers or three layers It is preferable that there are two layers.
　顔料としては公知のものを使用でき、具体的には、重質炭酸カルシウム、軽質炭酸カルシウム、ケイソウ土、タルク、カオリン、焼成カオリン、デラミネーティッドカオリン、重質炭酸カルシウム、軽質炭酸カルシウム、炭酸マグネシウム、炭酸バリウム、二酸化チタン、酸化亜鉛、酸化ケイ素、非晶質シリカ、亜硫酸カルシウム、石膏、ホワイトカーボン、水酸化アルミニウム、水酸化カルシウム、水酸化マグネシウム、水酸化亜鉛、製紙スラッジ、脱墨フロスからの再生無機粒子等の無機填料、尿素－ホルマリン樹脂、ポリスチレン樹脂、塩化ビニル樹脂、メラミン樹脂、フェノール樹脂、プラスチック微小中空粒子などの有機填料などを使用できる。 Known pigments can be used. Specifically, heavy calcium carbonate, light calcium carbonate, diatomaceous earth, talc, kaolin, calcined kaolin, delaminated kaolin, heavy calcium carbonate, light calcium carbonate, magnesium carbonate From barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, calcium sulfite, gypsum, white carbon, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, paper sludge, deinking floss Inorganic fillers such as regenerated inorganic particles, organic fillers such as urea-formalin resin, polystyrene resin, vinyl chloride resin, melamine resin, phenol resin, and plastic micro hollow particles can be used.
　ただし、顔料の総量１００重量部中カオリンまたはクレーの合計量は好ましくは２５重量部以下、より好ましくは２０重量部以下、さらに好ましくは１５重量部以下である。すなわち顔料の総量中、カオリンまたはクレーの合計量は２５重量％以下であることが好ましく、２０重量％以下であることがより好ましく、１５重量％以下であることがさらに好ましい。顔料の総量とは各顔料塗工層に含まれる顔料の合計量である。カオリンまたはクレーはアスペクト比が高く、高アスペクト比顔料と呼ばれることもある。高アスペクト比顔料としては、タルク、クレー、カオリン、焼成カオリン、デラミネーティッドカオリン等の板状顔料が挙げられる。従来はこのような板状顔料を使用して塗工層表面を平滑化して、すなわちミクロレベルで平滑にしてインキ擦れを低減することが試みられていた。一方、本発明においては輪郭塗工による顔料塗工層を設け、繊維によって形成された原紙表面の粗さを顔料塗工層に反映させて塗工層表面を粗化して、すなわちマクロレベルで粗化して印刷面との接点を減少させる。このため、本発明では板状顔料の量を低減させてもインキ擦れを低減できると考えられる。また、高アスペクト比の顔料を多く含む顔料塗工層は割れが発生することがあるため、顔料塗工層の割れの抑制のためにも、高アスペクト比顔料、特にカオリンまたはクレーの配合比率は低いことが好ましい。また、その他の顔料としては、白色度の高い炭酸カルシウムを用いることが好ましく、炭酸カルシウムとしては軽質炭酸カルシウムや重質炭酸カルシウムを用いることができる。 However, the total amount of kaolin or clay in the total amount of pigment of 100 parts by weight is preferably 25 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 15 parts by weight or less. That is, in the total amount of pigment, the total amount of kaolin or clay is preferably 25% by weight or less, more preferably 20% by weight or less, and further preferably 15% by weight or less. The total amount of pigment is the total amount of pigment contained in each pigment coating layer. Kaolin or clay has a high aspect ratio and is sometimes referred to as a high aspect ratio pigment. Examples of the high aspect ratio pigment include plate pigments such as talc, clay, kaolin, calcined kaolin, and delaminated kaolin. In the past, attempts have been made to reduce the ink rub by smoothing the surface of the coating layer using such a plate-like pigment, that is, smoothing at the micro level. On the other hand, in the present invention, a pigment coating layer is provided by contour coating, and the surface of the base paper formed by fibers is reflected in the pigment coating layer to roughen the coating layer surface, that is, rough at the macro level. To reduce the number of contacts with the printing surface. For this reason, in this invention, even if it reduces the quantity of a plate-shaped pigment, it is thought that ink rub can be reduced. In addition, since the pigment coating layer containing a lot of high aspect ratio pigments may crack, the blend ratio of high aspect ratio pigments, especially kaolin or clay, is also used to suppress cracking of the pigment coating layer. Preferably it is low. As other pigments, calcium carbonate with high whiteness is preferably used, and light calcium carbonate or heavy calcium carbonate can be used as calcium carbonate.
　例えば、２層の顔料塗工層を設ける場合、各層中の顔料を合計した総量中、カオリンまたはクレーの合計量が２５重量％以下であれば、カオリンまたはクレーの量は表層と下層で同じであってもよいし異なっていてもよい。例えば、表層のカオリンまたはクレーの配合率を３０重量％以下、下層のカオリンまたはクレーの配合率を５重量％以下とする等、表層におけるカオリンまたはクレーの量を下層よりも多くすることができる。また、下層に炭酸カルシウムを多く配合することで本発明の塗工白板紙に隠蔽性を付与し、表層にカオリンまたはクレーを配合することでミクロレベルの平滑性を付与することができる。 For example, when two pigment coating layers are provided, if the total amount of kaolin or clay is 25% by weight or less in the total amount of pigments in each layer, the amount of kaolin or clay is the same in the surface layer and the lower layer. It may be different or different. For example, the amount of kaolin or clay in the surface layer can be larger than that of the lower layer, for example, the proportion of kaolin or clay in the surface layer is 30% by weight or less and the proportion of kaolin or clay in the lower layer is 5% by weight or less. Further, it is possible to impart concealability to the coated white paperboard of the present invention by blending a large amount of calcium carbonate in the lower layer, and impart microlevel smoothness by blending kaolin or clay in the surface layer.
　顔料塗工層は公知の接着剤を含んでいてもよい。接着剤としては塗工紙用に従来から用いられているものを使用できる。接着剤の例としては、スチレン・ブタジエン系、スチレン・アクリル系、エチレン・酢酸ビニル系、ブタジエン・メチルメタクリレート系、酢酸ビニル・ブチルアクリレート系等の各種共重合体、ポリビニルアルコール、無水マレイン酸共重合体、およびアクリル酸・メチルメタクリレート系共重合体等の合成系接着剤；カゼイン、大豆蛋白、合成蛋白等の蛋白質類；酸化澱粉、陽性澱粉、尿素燐酸エステル化澱粉、酵素変性澱粉、ヒドロキシエチルエーテル化澱粉等のエーテル化澱粉、デキストリン等の澱粉類；カルボキシメチルセルロース、ヒドロキシエチルセルロース、ヒドロキシメチルセルロース等のセルロース誘導体等の通常の塗工紙用接着剤が挙げられる。接着剤は、１種類以上を適宜選択して使用できるが、少なくともスチレン・ブタジエン系共重合体を含有することが好ましい。 The pigment coating layer may contain a known adhesive. As the adhesive, those conventionally used for coated paper can be used. Examples of adhesives include styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, and other copolymers, polyvinyl alcohol, maleic anhydride copolymer Synthetic adhesives such as coalescence and acrylic acid / methyl methacrylate copolymers; proteins such as casein, soy protein, synthetic protein; oxidized starch, positive starch, urea phosphated starch, enzyme-modified starch, hydroxyethyl ether Examples thereof include ordinary coated paper adhesives such as etherified starch such as modified starch, starches such as dextrin; cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, and hydroxymethylcellulose. One or more types of adhesives can be appropriately selected and used, but it is preferable to contain at least a styrene / butadiene copolymer.
　顔料と接着剤の配合比率は、所望の顔料塗工液が得られる範囲で適宜調整される。通常、固形分比率で、顔料１００重量部に対し、接着剤５～３０重量部の範囲で含有することが好ましく、８～２０重量部とすることがさらに好ましい。接着剤の量が５重量部より少ないと、塗工層強度が弱くなってしまい、紙粉が発生したり、印刷強度が劣ることなどがある。また、接着剤の量が３０重量部より多いと、塗工層中の顔料粒子間の空隙が接着剤で満たされ塗工層の光散乱性が劣るため、不透明度が劣る、インキの吸収性が劣る、コストが高くなる等が生じうる。 The blending ratio of the pigment and the adhesive is appropriately adjusted within a range where a desired pigment coating solution can be obtained. Usually, the solid content ratio is preferably 5 to 30 parts by weight, more preferably 8 to 20 parts by weight with respect to 100 parts by weight of the pigment. When the amount of the adhesive is less than 5 parts by weight, the coating layer strength is weakened, and paper dust is generated or the printing strength is inferior. Further, when the amount of the adhesive is more than 30 parts by weight, the gap between the pigment particles in the coating layer is filled with the adhesive and the light scattering property of the coating layer is inferior. May be inferior, cost may increase, and the like.
　本発明の各塗工層を形成する塗工液には、顔料と接着剤の他に、必要に応じて、分散剤、粘性改良剤、保水剤、消泡剤、耐水化剤、蛍光染料、着色染料、着色顔料、界面活性剤、ｐＨ調整剤、カチオン性樹脂、アニオン性樹脂、紫外線吸収剤、金属塩など、通常の塗工紙用顔料に配合される各種助剤を適宜使用できる。 In the coating liquid for forming each coating layer of the present invention, in addition to the pigment and the adhesive, if necessary, a dispersant, a viscosity improver, a water retention agent, an antifoaming agent, a water resistant agent, a fluorescent dye, Various auxiliaries blended into ordinary coated paper pigments such as colored dyes, colored pigments, surfactants, pH adjusters, cationic resins, anionic resins, ultraviolet absorbers and metal salts can be used as appropriate.
　顔料塗工層の総量は限定されないが、片面あたり１０～３５ｇ／ｍ２程度であることが好ましく、１５～３０ｇ／ｍ２程度であることがより好ましい。 The total amount of the pigment coating layer is not limited, but is preferably about 10 to 35 g / m 2 per side, and more preferably about 15 to 30 g / m 2 .
　前記顔料塗工層は輪郭塗工層である。輪郭塗工層とは、原紙の輪郭をなぞるように設けられた均一な塗工層であり、原紙表面の凹凸をほぼ再現している塗工層である。輪郭塗工層は、輪郭塗工方式の塗工装置で形成され、例えばカーテン塗工方式、エアナイフ塗工方式、スプレー塗工方式、接触型輪郭塗工方式などの塗工装置などによって形成できるがこれらに限定されない。カーテン塗工方式で塗工層を設けるカーテン塗工については後で詳述する。顔料塗工層が複数存在する場合、すべての顔料塗工層は輪郭塗工層であることが好ましい。 The pigment coating layer is a contour coating layer. The contour coating layer is a uniform coating layer provided so as to trace the contour of the base paper, and is a coating layer that substantially reproduces the irregularities on the surface of the base paper. The contour coating layer is formed by a contour coating method coating apparatus, and can be formed by a coating device such as a curtain coating method, an air knife coating method, a spray coating method, or a contact type contour coating method. It is not limited to these. The curtain coating in which the coating layer is provided by the curtain coating method will be described in detail later. When a plurality of pigment coating layers are present, all the pigment coating layers are preferably contour coating layers.
（３）クリア塗工層
　本発明の塗工白板紙は、原紙層と顔料塗工層の間に、上述の顔料塗工層に用いられる各種接着剤や、各種助剤から成るクリア塗工層を有していてもよい。ただし、顔料塗工層表面に原紙層表面の凹凸を反映させる観点から、クリア塗工層を設ける場合、その塗工量は少ないことが好ましく、具体的には０．１～５ｇ／ｍ２程度であることが好ましい。クリア塗工層は輪郭塗工層である必要はない。 (3) Clear coating layer The coated white paperboard of the present invention is a clear coating layer comprising various adhesives and various auxiliaries used for the above-mentioned pigment coating layer between the base paper layer and the pigment coating layer. You may have. However, from the viewpoint of reflecting the unevenness of the surface of the base paper layer on the surface of the pigment coating layer, when a clear coating layer is provided, the coating amount is preferably small, specifically about 0.1 to 5 g / m 2. It is preferable that The clear coating layer need not be a contour coating layer.
（４）裏面
　本発明の塗工白板紙は、一方の面に輪郭塗工による顔料塗工層を有していればよいが、他方の面（便宜上「裏面」ともいう）にクリア塗工層もしくは顔料塗工層を設けてもよい。他方の面に塗工層を設けることで、剛度を向上させる、またはカールを抑制することができる。裏面塗工層は、必要に応じて、公知の顔料やバインダー、および、分散剤、粘性改良剤、保水剤、消泡剤、耐水化剤、蛍光染料、着色染料、着色顔料、界面活性剤、ｐＨ調整剤、カチオン性樹脂、アニオン性樹脂、紫外線吸収剤、金属塩などを含んでいてよい。裏面のクリアもしくは顔料塗工層は輪郭塗工である必要はなく、ブレード塗工などの公知の方法で設けてよい。その塗工量は、特に制限されないが、一般的に片面あたり固形分で０．１～５ｇ／ｍ２である。 (4) Back side The coated white paperboard of the present invention may have a pigment coating layer by contour coating on one side, but a clear coating layer on the other side (also referred to as “back side” for convenience). Alternatively, a pigment coating layer may be provided. By providing a coating layer on the other surface, rigidity can be improved or curling can be suppressed. The back coating layer is, as necessary, known pigments and binders, dispersants, viscosity improvers, water retention agents, antifoaming agents, water resistance agents, fluorescent dyes, colored dyes, colored pigments, surfactants, It may contain a pH adjuster, a cationic resin, an anionic resin, an ultraviolet absorber, a metal salt, and the like. The clear or pigment coating layer on the back surface does not need to be contour coating, and may be provided by a known method such as blade coating. The coating amount is not particularly limited, but is generally 0.1 to 5 g / m 2 in terms of solid content on one side.
（５）特性
１）平滑性
　本発明の塗工白板紙は、原紙レベルの凹凸を反映した適度な平滑性を有することが好ましい。平滑性は表面の凹凸度合の指標であり、王研式平滑度や、ＰＰＳラフネス、ＫＥＹＥＮＣＥ社のワンショット３Ｄ測定マイクロスコープなどを用いた画像処理によって求めた塗工層表面の高さ分布などにより測定されるが、これらに限定されない。平滑性が高すぎると、紙同士の接触面積が大きくなりインキ擦れが悪化してしまったり、光沢度が上がりすぎてしまうため、本発明のインキ擦れの低減効果や、適切な白紙光沢度を得ることが困難になる。また、平滑性が低すぎると印刷面感や搬送性の悪化を招く可能性がある。 (5) Characteristic 1) Smoothness It is preferable that the coated white paperboard of the present invention has appropriate smoothness reflecting irregularities at the base paper level. Smoothness is an index of the degree of unevenness of the surface, depending on the surface distribution of the coating layer obtained by Oken-type smoothness, image processing using PPS roughness, KEYENCE one-shot 3D measurement microscope, etc. Although measured, it is not limited to these. If the smoothness is too high, the contact area between the papers becomes large and the ink rubbing deteriorates or the glossiness increases too much. Therefore, the ink rubbing reduction effect of the present invention and an appropriate white paper glossiness are obtained. It becomes difficult. On the other hand, if the smoothness is too low, there is a possibility that the printing surface feeling and the transportability are deteriorated.
　１－１）ＰＰＳラフネス
　本発明の塗工白板紙は、クランプ圧２０００ｋＰａの条件におけるＰＰＳラフネスが１．３μｍ超３．０μｍ以下である。上限は、好ましくは２．５μｍ以下、さらに好ましくは２．３μｍ以下である。ＰＰＳラフネスはＩＳＯ８７９１に準じて測定される塗工白板紙の表面の粗度を表す指標である。ＰＰＳラフネスが前記範囲である塗工白板紙は、原紙表面の繊維レベルの凹凸を反映しており、これによってインキ擦れが低減される。ＰＰＳラフネスが１．３μｍ以下だと、平滑性が高くなってしまいインキ擦れが発生する可能性がある。ＰＰＳラフネスは、数値が高すぎると塗工紙表面の凹凸が大きくなり、白紙光沢度の低下や、印刷面感の悪化を引き起こす傾向がある。２．３μｍより高いとその可能性が高くなり、３．０μｍより高いとその傾向がより顕著となるため、これらの観点からＰＰＳラフネスは１．３μｍ超２．３μｍ以下が好ましい。 1-1) PPS roughness The coated white paperboard of the present invention has a PPS roughness of more than 1.3 μm and not more than 3.0 μm under the condition of a clamp pressure of 2000 kPa. The upper limit is preferably 2.5 μm or less, more preferably 2.3 μm or less. The PPS roughness is an index representing the roughness of the surface of the coated white paperboard measured according to ISO8791. The coated white paperboard having the PPS roughness in the above range reflects the unevenness of the fiber level on the surface of the base paper, thereby reducing ink rub. If the PPS roughness is 1.3 μm or less, the smoothness becomes high and ink scuffing may occur. When the PPS roughness is too high, the unevenness of the coated paper surface becomes large, and there is a tendency that the glossiness of the white paper is lowered and the printing surface is deteriorated. If it is higher than 2.3 μm, the possibility increases, and if it is higher than 3.0 μm, the tendency becomes more prominent. From these viewpoints, the PPS roughness is preferably more than 1.3 μm and 2.3 μm or less.
　また、原紙の２０００ｋＰａの条件におけるＰＰＳラフネスは５～１５μｍである。上限は好ましくは、１４μｍ以下、さらに好ましくは１２μｍ以下であり、下限は好ましくは６μｍ以上、さらに好ましくは８μｍ以上である。前述の通り、本発明の塗工白板紙は輪郭塗工により顔料塗工層を設けるため、原紙の凹凸が塗工白板紙の凹凸に反映され、インク擦れを低減することができる。そのため、原紙のＰＰＳラフネスが上記範囲内であると、輪郭塗工層を設けた後の塗工白板紙表面に、十分な凹凸が形成され、インキ擦れを低減した塗工白板紙を得ることができる。 Also, the PPS roughness of the base paper under the condition of 2000 kPa is 5 to 15 μm. The upper limit is preferably 14 μm or less, more preferably 12 μm or less, and the lower limit is preferably 6 μm or more, more preferably 8 μm or more. As described above, since the coated white board of the present invention is provided with a pigment coating layer by contour coating, the unevenness of the base paper is reflected in the unevenness of the coated white board, and ink rubbing can be reduced. Therefore, when the PPS roughness of the base paper is within the above range, it is possible to obtain a coated white paperboard in which sufficient irregularities are formed on the surface of the coated white paperboard after the contour coating layer is provided, and ink rubbing is reduced. it can.
　１－２）画像処理により求めた高さ分布のＤ５０値
　本発明の塗工白板紙は、画像処理により求めた塗工層表面の高さ分布のＤ５０値が５以上、２５％以下であることが好ましい。当該Ｄ５０も塗工白板紙の表面の粗度を表す指標であり、Ｄ５０がこの範囲にあるとインキ擦れが低減される。塗工層表面の高さ分布を画像処理により求める装置としては、例えば（株）ＫＥＹＥＮＣＥ社製のワンショット３Ｄ測定マイクロスコープ（商品名：ＶＲ－３１００）等が挙げられる。 1-2) D50 value of height distribution obtained by image processing In the coated white paperboard of the present invention, the D50 value of the height distribution of the coating layer surface obtained by image processing is 5 or more and 25% or less. Is preferred. The D50 is also an index representing the surface roughness of the coated white paperboard, and if the D50 is within this range, ink scuffing is reduced. An apparatus for obtaining the height distribution on the surface of the coating layer by image processing includes, for example, a one-shot 3D measurement microscope (trade name: VR-3100) manufactured by KEYENCE Corporation.
　２）ＤＡＶ２値
　本発明の塗工白板紙は、ＤＡＶ２値が５０以下であることが好ましい。ＤＡＶ２値はデュポン社製アピアランスアナライザーを用いて測定される、塗工紙表面のもやもや感を表す指標である。この値が低いほどもやもや感が低いことを示す。ＤＡＶ２値が５０より高いと、もやもや感が高く、箱などの容器として使用された際に、外観性の観点から問題となる場合がある。 2) DAV2 value The coated white paperboard of the present invention preferably has a DAV2 value of 50 or less. The DAV2 value is an index representing the feeling of haze on the coated paper surface measured using an appearance analyzer manufactured by DuPont. The lower the value, the lower the haze. When the DAV2 value is higher than 50, the feeling is somewhat high, and when used as a container such as a box, there may be a problem from the viewpoint of appearance.
　３）白紙光沢度
　本発明の塗工白板紙は、白紙光沢度が４５～６０％であることが好ましい。本発明の白紙光沢度はＪＩＳ－Ｐ８１４２にしたがって測定される光沢度の指標である。 3) White paper gloss The coated white paperboard of the present invention preferably has a white paper gloss of 45 to 60%. The white paper glossiness of the present invention is an index of glossiness measured according to JIS-P8142.
　４）白色度
　本発明の塗工白板紙の白色度は７５～８５％であることが好ましく、原紙の白色度は６０～７５％であることが好ましい。原紙の白色度が上記範囲であると、白色度に優れた塗工白板紙を得ることができる。ただし、本発明によれば、輪郭塗工により原紙被覆性の高い顔料塗工層を設けることができるため、例え低白色度の原紙を用いたとしても、白色ムラが少なく、白色度の高い塗工白板紙を得ることができる。白色度は、ＪＩＳ　Ｐ８１４８「紙、板紙及びパルプ－ＩＳＯ白色度（拡散青色光反射率）の測定方法」に従い測定される。 4) Whiteness The whiteness of the coated white board of the present invention is preferably 75 to 85%, and the whiteness of the base paper is preferably 60 to 75%. When the whiteness of the base paper is within the above range, a coated white board with excellent whiteness can be obtained. However, according to the present invention, it is possible to provide a pigment coating layer having a high base paper covering property by contour coating, so even if a low white base paper is used, there is little white unevenness and high whiteness coating. Engineered white paperboard can be obtained. The whiteness is measured in accordance with JIS P8148 “Paper, paperboard and pulp—Method of measuring ISO whiteness (diffuse blue light reflectance)”.
　５）坪量
　本発明の塗工白板紙の坪量は、特に限定されないが、１５０～８００ｇ／ｍ２程度が好ましい。 5) Basis weight The basis weight of the coated white paperboard of the present invention is not particularly limited, but is preferably about 150 to 800 g / m 2 .
（６）効果発現のメカニズム
　本発明の塗工白板紙は、優れた耐インキ擦れ性を有する。この理由は限定されないが、本発明の塗工白板紙は全顔料塗工層が輪郭塗工により設けられるため、ブレード塗工等の接触型塗工方式のみで設けられた塗工層とは異なり、塗工白板紙表面の凹凸が原紙層の繊維レベルでの凹凸が塗工層表面にも反映される。そのため、紙を重ねた際の紙同士の接触面積が少なく、印字部分に当該表面が擦れたとしても印字部分を表面で掻き取ることが生じにくいためと考えられる。さらに、輪郭塗工層は層の均一性に優れるため、白色ムラも低減できる。 (6) Mechanism of manifestation of effect The coated white paperboard of the present invention has excellent ink rub resistance. The reason for this is not limited, but the coated white paperboard of the present invention is provided with the entire pigment coating layer by contour coating, so it is different from the coating layer provided only by the contact coating method such as blade coating. The unevenness on the surface of the coated white paperboard is also reflected on the surface of the coated layer. Therefore, it is considered that the contact area between the papers when the papers are stacked is small, and even if the surface is rubbed against the print part, it is difficult to scrape the print part on the surface. Furthermore, since the contour coating layer is excellent in layer uniformity, white unevenness can also be reduced.
２．製造方法
　本発明の塗工白板紙は、原紙上に輪郭塗工方式の塗工装置を用いて２層以上の顔料塗工層を設けて製造することが好ましい。輪郭塗工は、原紙等の基材の凹凸に沿った均一な膜厚な塗工層を設ける塗工方式である。輪郭塗工方式は、繊維レベルの凹凸を反映した塗工層が形成されるため、得られた塗工紙は、原紙の隠蔽性が高い、ブレード塗工方式と比較して平滑性光沢度が低い等の特徴をもつ。輪郭塗工方式の塗工方法としては、カーテン塗工、エアナイフ塗工、スプレー塗工、各種接触型輪郭塗工などが挙げられるが、本発明の輪郭塗工は、カーテン塗工であることが好ましい。カーテン塗工とは、前計量方式の塗工方法であり、塗工量に合わせて流量などを調節した塗工液をカーテン状に流下させて膜を形成し、その膜に原紙を通すことにより原紙上に塗工層を設ける塗工方式である。そのため、原紙上の凹凸を塗工層表面に再現しやすい。また、カーテン塗工は、ブレードによる掻き落としがなく、カーテン膜として形成された塗工層がそのまま原紙に載せられるため、塗工層の空隙が多く、光散乱性や白色度の点でも好ましい。 2. Production Method The coated white paperboard of the present invention is preferably produced by providing two or more pigment coating layers on a base paper using a contour coating type coating apparatus. The contour coating is a coating method in which a coating layer having a uniform film thickness along the unevenness of a base material such as a base paper is provided. The contour coating method forms a coating layer that reflects the unevenness of the fiber level, so the resulting coated paper has a high level of glossiness compared to the blade coating method. Features such as low. Examples of the coating method of the contour coating method include curtain coating, air knife coating, spray coating, various contact type contour coating, etc., but the contour coating of the present invention may be curtain coating. preferable. Curtain coating is a pre-measuring method, in which a film is formed by flowing a coating liquid whose flow rate is adjusted according to the coating amount into a curtain shape, and the base paper is passed through the film. This is a coating method in which a coating layer is provided on a base paper. Therefore, the unevenness on the base paper can be easily reproduced on the surface of the coating layer. Also, curtain coating is not scraped off by a blade, and the coating layer formed as a curtain film is placed on the base paper as it is, so that there are many voids in the coating layer, which is preferable in terms of light scattering and whiteness.
　カーテン塗工には公知の装置を使用することができる。カーテン塗工装置の形状として公知であるものは、ダイから塗工液を下向きに吐出することにより直接カーテン膜を形成するスロット型カーテン塗工装置と、ダイから塗工液を上向きに吐出し、ダイ上の斜面で塗工液の膜を形成しつつ流動していき、その後ダイを離れて自由落下することによりカーテン膜を形成するスライド型カーテン塗工装置がある。本発明においてはいずれの装置を使用してもよいが、スロット型を用いて２層以上のカーテン膜を同時に形成して多層塗工することが好ましい。塗工速度も特に限定されず、１００～６００ｍ／分程度とすることができる。 A well-known apparatus can be used for curtain coating. What is known as the shape of the curtain coating apparatus is a slot type curtain coating apparatus that directly forms a curtain film by discharging the coating liquid downward from the die, and discharging the coating liquid upward from the die, There is a slide-type curtain coating apparatus that flows while forming a coating liquid film on a slope on a die, and then forms a curtain film by free-falling after leaving the die. In the present invention, any apparatus may be used, but it is preferable to apply multilayer coating by simultaneously forming two or more curtain films using a slot mold. The coating speed is not particularly limited, and can be about 100 to 600 m / min.
　塗工液の固形分濃度は、５８重量％以上が好ましく、６２重量％以上がより好ましい。固形分が５８重量％より低いと、塗工液の原紙への過剰な浸透により塗工紙の品質が低下することがある。一方、固形分濃度の上限は特に制限されないが、送液性等を考慮すると、７５重量％以下が好ましく、７０重量％以下がより好ましい。 The solid content concentration of the coating liquid is preferably 58% by weight or more, and more preferably 62% by weight or more. When the solid content is lower than 58% by weight, the quality of the coated paper may deteriorate due to excessive penetration of the coating liquid into the base paper. On the other hand, the upper limit of the solid content concentration is not particularly limited, but is preferably 75% by weight or less and more preferably 70% by weight or less in consideration of liquid feeding properties.
［実施例１］
（原紙１）
　ＬＢＫＰ１００重量％のパルプを使用して坪量３３ｇ／ｍ２の表層、脱墨古紙パルプ８０重量％、脱墨しない雑誌古紙パルプ２０重量％を配合して坪量３６ｇ／ｍ２の表下層、脱墨しない雑誌古紙パルプ１００重量％のパルプを使用して坪量４４ｇ／ｍ２の中層、中層と同様のパルプを使用して４～７層目をそれぞれ抄造して抄き合わせ、プレス、乾燥処理を行い坪量２９４ｇ／ｍ２の塗工白板紙原紙を得た。本発明では、多層抄きの原紙において、顔料を塗工する側の最表層を表層、塗工面から反対側に向かって２層目を表下層、最裏面を裏層、それ以外を中層という。 [Example 1]
(Base paper 1)
Using LBKP 100% by weight pulp, surface layer of 33g / m 2 basis weight, deinked waste paper pulp 80% by weight, non-deinked magazine waste paper pulp 20% by weight, basis weight 36g / m 2 surface layer, Made from 100% by weight of non-black magazine paper pulp, the 4th to 7th layers are made using the same middle and middle layer pulps with a basis weight of 44g / m 2 and combined, pressed and dried. A coated white paperboard base paper having a basis weight of 294 g / m 2 was obtained. In the present invention, in the multilayer paper, the outermost layer on the side on which the pigment is applied is referred to as the surface layer, the second layer from the coated surface to the opposite side is referred to as the lower layer, the outermost surface is referred to as the back layer, and the other layers are referred to as the middle layer.
（塗工液Ａ）
　紡錘状軽質炭酸カルシウム（Ｄ５０＝０．５μｍ、Ｄ７５／Ｄ２５＝２．５）１００重量部からなる顔料スラリーを調製した後、顔料１００重量部に対して、スチレン・ブタジエン共重合ラテックス１８重量部、界面活性剤０．２重量部を添加した。さらに水を添加して、３０℃、６０ｒｐｍにおけるＢ型粘度が１０００ｍＰａ・ｓになるように調整し、固形分濃度６２重量％、静的表面張力３８ｍＮ／ｍの塗工液Ａを得た。 (Coating fluid A)
After preparing a pigment slurry consisting of 100 parts by weight of spindle-shaped light calcium carbonate (D50 = 0.5 μm, D75 / D25 = 2.5), 18 parts by weight of styrene / butadiene copolymer latex with respect to 100 parts by weight of pigment, 0.2 part by weight of a surfactant was added. Water was further added to adjust the B-type viscosity at 30 ° C. and 60 rpm to 1000 mPa · s to obtain a coating liquid A having a solid content concentration of 62% by weight and a static surface tension of 38 mN / m.
（塗工液Ｂ）
　重質炭酸カルシウム（Ｄ５０＝０．７μｍ、Ｄ７５／Ｄ２５＝３．８）７０重量部、デラミネーティッドカオリン（平均アスペクト比５０）２５重量部、酸化チタン５重量部からなる顔料スラリーを調整した後、顔料１００重量部に対して、スチレン・ブタジエン共重合ラテックス１４重量部、界面活性剤０．２重量部を添加した。さらに水を添加して６０ｒｐｍにおけるＢ型粘度が１０００ｍＰａ・ｓになるように調整し、固形分濃度６８重量％、静的表面張力は３０ｍＮ／ｍの塗工液Ｂを得た。 (Coating fluid B)
After preparing a pigment slurry consisting of 70 parts by weight of heavy calcium carbonate (D50 = 0.7 μm, D75 / D25 = 3.8), 25 parts by weight of delaminated kaolin (average aspect ratio 50) and 5 parts by weight of titanium oxide The styrene / butadiene copolymer latex 14 parts by weight and the surfactant 0.2 parts by weight were added to 100 parts by weight of the pigment. Water was further added to adjust the B-type viscosity at 60 rpm to 1000 mPa · s to obtain a coating liquid B having a solid content concentration of 68% by weight and a static surface tension of 30 mN / m.
（塗工）
　原紙１の片面に上記塗工液Ｂが最表層になるよう、塗工液ＡおよびＢをスロット型カーテン塗工装置にて同時２層塗工を行い、乾燥した。カーテン塗工層は、塗工液Ａの層をプレ塗工層、塗工液Ｂの層をトップ塗工層とした。塗工量は、乾燥後の重量でプレ塗工層が２０ｇ／ｍ２、トップ塗工層が５ｇ／ｍ２であり、塗工白板紙の坪量は３１６．３ｇ／ｍ２であった。塗工速度は、オンマシンにより抄紙と一貫して行ったため、抄紙速度と同じく３００ｍ／ｍｉｎであった。 (Coating)
Two coatings of coating liquids A and B were simultaneously applied by a slot type curtain coating apparatus so that the coating liquid B was the outermost layer on one side of the base paper 1 and dried. For the curtain coating layer, the coating liquid A layer was a pre-coating layer, and the coating liquid B layer was a top coating layer. Amount of coating is pre-coated layer weight after drying of 20 g / m 2, the top coating layer is 5 g / m 2, the basis weight of the coated white paperboard was 316.3 g / m 2. The coating speed was 300 m / min, the same as the papermaking speed, since it was performed consistently with the papermaking by on-machine.
（仕上げ処理）
　得られた塗工白板紙をカレンダー処理することにより、塗工白板紙を得た。処理速度は、オンマシンにより抄紙、塗工と一貫して行ったため、抄紙速度および塗工速度と同じく３００ｍ／ｍｉｎであった。 (Finishing process)
The coated white paperboard obtained was calendered to obtain a coated white paperboard. The processing speed was 300 m / min, which was the same as the papermaking speed and the coating speed, because it was performed consistently with the papermaking and coating by on-machine.
［実施例２］
　原紙１の片面に上記塗工液Ｂをスロット型カーテン塗工装置にて単層塗工を行った以外は、実施例１と同様にして塗工白板紙を得て評価した。塗工量は、乾燥後の重量で２５ｇ／ｍ２であり、塗工白板紙の坪量は３１６．５ｇ／ｍ２であった。 [Example 2]
A coated white board was obtained and evaluated in the same manner as in Example 1 except that the coating liquid B was applied to one side of the base paper 1 with a slot type curtain coating apparatus. The coating amount was 25 g / m 2 by weight after drying, and the basis weight of the coated white paperboard was 316.5 g / m 2 .
［比較例１］
（塗工液Ｃ）
　デラミネーティッドカオリン（平均アスペクト比５０）３５重量部、重質炭酸カルシウム（Ｄ５０＝０．７μｍ、Ｄ７５／Ｄ２５＝３．８）６５重量部からなる顔料スラリーを調製した後、顔料１００重量部に対して、尿素リン酸澱粉３重量部、スチレン・ブタジエン共重合ラテックス１２重量部を添加した。さらに水を添加して、３０℃、６０ｒｐｍにおけるＢ型粘度が１０００ｍＰａ・ｓになるように調整し、固形分濃度６５重量％、静的表面張力３０ｍＮ／ｍの塗工液Ｃを得た。 [Comparative Example 1]
(Coating fluid C)
After preparing a pigment slurry consisting of 35 parts by weight of delaminated kaolin (average aspect ratio 50) and 65 parts by weight of heavy calcium carbonate (D50 = 0.7 μm, D75 / D25 = 3.8), On the other hand, 3 parts by weight of urea phosphate starch and 12 parts by weight of styrene / butadiene copolymer latex were added. Further, water was added to adjust the B-type viscosity at 30 ° C. and 60 rpm to 1000 mPa · s to obtain a coating liquid C having a solid content concentration of 65% by weight and a static surface tension of 30 mN / m.
（塗工液Ｄ）
　デラミネーティッドカオリン（平均アスペクト比５０）２５重量部、クレー（平均アスペクト比２５）２５重量部、重質炭酸カルシウム（Ｄ５０＝０．７μｍ、Ｄ７５／Ｄ２５＝３．８）５重量部、紡錘状軽質炭酸カルシウム（Ｄ５０＝０．５μｍ、Ｄ７５／Ｄ２５＝２．５）３８重量部、酸化チタン７重量部からなる顔料スラリーを調製した後、顔料１００重量部に対して、尿素リン酸澱粉５重量部、スチレン・ブタジエン共重合ラテックス１４．５重量部を添加した。さらに水を添加して、３０℃、６０ｒｐｍにおけるＢ型粘度が１０００ｍＰａ・ｓになるように調整し、固形分濃度６２重量％、静的表面張力３０ｍＮ／ｍの塗工液Ｄを得た。 (Coating fluid D)
25 parts by weight of delaminated kaolin (average aspect ratio 50), 25 parts by weight of clay (average aspect ratio 25), 5 parts by weight of heavy calcium carbonate (D50 = 0.7 μm, D75 / D25 = 3.8), spindle shape After preparing a pigment slurry comprising 38 parts by weight of light calcium carbonate (D50 = 0.5 μm, D75 / D25 = 2.5) and 7 parts by weight of titanium oxide, 5 parts by weight of urea phosphate starch with respect to 100 parts by weight of pigment. 14.5 parts by weight of styrene / butadiene copolymer latex was added. Further, water was added to adjust the B-type viscosity at 30 ° C. and 60 rpm to 1000 mPa · s to obtain a coating liquid D having a solid content concentration of 62% by weight and a static surface tension of 30 mN / m.
　実施例１において、原紙１の４～７層目の坪量配分を調整して２９５ｇ／ｍ２とした原紙に、プレ塗工層として、塗工液Ｃをバー塗工にて塗工し、乾燥工程を経た後に、トップ塗工層として塗工液Ｄをベントブレード塗工方式にて塗工した。塗工量は、乾燥後の重量でプレ塗工層が８ｇ／ｍ２、トップ塗工層が１２ｇ／ｍ２であり、塗工白板紙の坪量は３１５．１ｇ／ｍ２であった。塗工層の構成以外は、実施例１と同様にして塗工白板紙を得た。 In Example 1, the base paper 1 was adjusted to have a basis weight distribution of 295 g / m 2 by adjusting the basis weight distribution of the fourth to seventh layers, and the coating liquid C was applied as a pre-coating layer by bar coating. After passing through the drying step, the coating liquid D was applied as a top coating layer by a vent blade coating method. Amount of coating is pre-coated layer weight after drying of 8 g / m 2, the top coating layer is 12 g / m 2, the basis weight of the coated white paperboard was 315.1g / m 2. A coated white paperboard was obtained in the same manner as in Example 1 except for the configuration of the coating layer.
［比較例２］
　カレンダー処理を実施しなかった以外は実施例１と同様にして塗工白板紙を得て評価した。塗工白板紙の坪量は３１８．５ｇ／ｍ２であった。 [Comparative Example 2]
A coated white paperboard was obtained and evaluated in the same manner as in Example 1 except that the calendar process was not performed. The basis weight of the coated white paperboard was 318.5g / m 2.
［比較例３］
　比較例１で用いた原紙の上に塗工液Ｄをベントブレード塗工方式にて塗工し、プレ塗工層を形成した。次いで、上記塗工液Ｂが最表層になるよう、塗工液ＡおよびＢをスロット型カーテン塗工装置にて同時２層塗工を行い、乾燥した。塗工量は、乾燥後の重量でプレ塗工層が１０ｇ／ｍ２、中間塗工層が１０ｇ／ｍ２、トップ塗工層が５ｇ／ｍ２であり塗工白板紙の坪量は３１７．９ｇ／ｍ２であった。 [Comparative Example 3]
The coating liquid D was applied onto the base paper used in Comparative Example 1 by a vent blade coating method to form a pre-coating layer. Next, the coating liquids A and B were simultaneously applied to the coating liquid B by a slot type curtain coating apparatus so that the coating liquid B was the outermost layer, and dried. Amount of coating is pre-coated layer is 10 g / m 2 by weight of the dry basis weight of the intermediate coating layer 10 g / m 2, the top coating layer is 5 g / m 2 coated white paperboard 317 0.9 g / m 2 .
　このようにして調製した塗工白板紙を以下のとおりに評価した。結果を表１に示す。
（１）坪量：ＪＩＳ　Ｐ　８１２４に準じて測定した。
（２）紙厚：ＪＩＳ　Ｐ　８１１８に準じて測定した。
（３）密度：ＪＩＳ　Ｐ　８１１８に準じて坪量と紙厚から求めた。
（４）王研平滑度：ＪＩＳ　Ｐ　８１５５に準じて測定した。
（５）ＰＰＳラフネス：ＩＳＯ８７９１に準じて測定したＰＰＳ表面粗さ。ソフトバッキングで測定した。
（６）白紙光沢度：ＪＩＳ－Ｐ８１４２に基づいて測定した。
（７）白色度：ＪＩＳ　Ｐ８１４８に準じて測定した。
（８）インキ擦れ：ローランド社製オフセット枚葉印刷機（４色）にてオフセット枚葉用インキ（東洋インキ製ＮＥＸ－Ｍ）を用い、印刷速度８０００枚／ｈｒでベタ部のインキ着肉濃度が墨１．８０となる様に印刷したあと、ＪＩＳ　Ｐ８１１１に基づき２４時間調湿し、学振型摩擦堅牢度試験機により、墨ベタ印刷部が白紙部に合わさるように５００ｇｆの荷重をかけて１回擦り合わせ、白紙部に転移したインキをインキ擦れとして目視評価した。
　　Ａ：良好
　　Ｂ：不良
（９）ＤＡＶ２：デュポン社製アピアランスアナライザーを用い、塗工紙表面のもやもや感を評価した。値が大きいほど塗工紙の表面にもやもや感があり、白紙面感が劣る。
（１０）印刷面感
　目視にて評価した。
　　Ａ：良好
　　Ｂ：不良 The coated white paperboard thus prepared was evaluated as follows. The results are shown in Table 1.
(1) Basis weight: Measured according to JIS P 8124.
(2) Paper thickness: Measured according to JIS P 8118.
(3) Density: Determined from basis weight and paper thickness according to JIS P 8118.
(4) Oken smoothness: measured according to JIS P 8155.
(5) PPS roughness: PPS surface roughness measured according to ISO8791. Measured with soft backing.
(6) Glossiness of blank paper: measured based on JIS-P8142.
(7) Whiteness: Measured according to JIS P8148.
(8) Ink rubbing: Ink density of solid part at a printing speed of 8000 sheets / hr using offset sheet-fed ink (NEX-M manufactured by Toyo Ink) with an offset sheet-fed printing machine (4 colors) manufactured by Roland After printing so that the ink becomes 1.80, the humidity is adjusted for 24 hours according to JIS P8111, and a load of 500 gf is applied by the Gakushin type friction fastness tester so that the black solid printing part fits the blank paper part. The ink which rubbed once and transferred to the white paper portion was visually evaluated as ink rubbing.
A: Good B: Poor (9) DAV2: The appearance feeling of the coated paper was evaluated using an appearance analyzer manufactured by DuPont. The larger the value is, the more slightly the surface of the coated paper is, and the lower the blank paper feel.
(10) Print surface feeling Evaluated visually.
A: Good B: Bad
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　本発明の塗工白板紙は、優れた耐インキ擦れ性を有する。 The coated white paperboard of the present invention has excellent ink rub resistance.

Claims (5)

  1. 　原紙および顔料塗工層を備える塗工白板紙であって、
    　前記顔料塗工層が輪郭塗工層であり、
    　クランプ圧２０００ｋＰａの条件におけるＰＰＳラフネスが１．３μｍ超３．０μｍ以下である、塗工白板紙。     Coated white board with a base paper and a pigment coating layer,
    The pigment coating layer is a contour coating layer,
    Coated white paperboard having a PPS roughness of more than 1.3 μm and not more than 3.0 μm under the condition of a clamping pressure of 2000 kPa.
  2. 　前記顔料塗工層中の顔料の総量１００重量部中、カオリンまたはクレーの合計量が２５重量部以下である、請求項１記載の塗工白板紙。 The coated white paperboard according to claim 1, wherein the total amount of kaolin or clay is 25 parts by weight or less in 100 parts by weight of the total amount of pigment in the pigment coating layer.
  3. 　前記輪郭塗工層がカーテン塗工層である、請求項１または２に記載の塗工白板紙。 The coated white paperboard according to claim 1 or 2, wherein the contour coating layer is a curtain coating layer.
  4. 　アピアランスアナライザーによって測定されるＤＡＶ２値が５０以下である、請求項１～３のいずれかに記載の塗工白板紙。 The coated white paperboard according to any one of claims 1 to 3, wherein the DAV2 value measured by an appearance analyzer is 50 or less.
  5. 　白紙光沢度が４５～６０％である、請求項１～４のいずれかに記載の塗工白板紙。
          The coated white paperboard according to any one of claims 1 to 4, wherein the glossiness of the white paper is 45 to 60%.
PCT/JP2017/038076 2016-10-20 2017-10-20 Coated white paperboard WO2018074604A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015074860A (en) * 2013-10-11 2015-04-20 王子ホールディングス株式会社 Method of producing coated white paperboard
JP2015193949A (en) * 2014-03-31 2015-11-05 日本製紙株式会社 coated white paperboard
JP2015196907A (en) * 2014-03-31 2015-11-09 日本製紙株式会社 coated white paperboard
JP2016060974A (en) * 2014-09-16 2016-04-25 王子ホールディングス株式会社 Coated white paperboard

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015074860A (en) * 2013-10-11 2015-04-20 王子ホールディングス株式会社 Method of producing coated white paperboard
JP2015193949A (en) * 2014-03-31 2015-11-05 日本製紙株式会社 coated white paperboard
JP2015196907A (en) * 2014-03-31 2015-11-09 日本製紙株式会社 coated white paperboard
JP2016060974A (en) * 2014-09-16 2016-04-25 王子ホールディングス株式会社 Coated white paperboard

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