JP2010126854A - Pigment-coated paper for printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide pigment-coated paper for printing which is suitable for hybrid printing having excellent offset printability, and further recording suitability to a high-speed inkjet printer. <P>SOLUTION: The pigment-coated paper for printing includes at least two pigment-coated layers provided on at least one surface of base paper. The outermost layer of the pigment-coated layers contains: not less than 50 pts.mass of kaolin in 100 pts.mass of the pigment; and 4-10 pts.mass of an SBR latex as a binder, based on 100 pts.mass of the pigment. The inside coating layer provided between the outermost layer and base paper contains 50-90 pts.mass of precipitated calcium carbonate having an average particle diameter of 0.05-0.8 μm, and 10-25 pts.mass of an organic or inorganic pigment having an average particle diameter of 1.0-5.0 μm in 100 pts.mass of the pigment; and 10-30 pts.mass of the SBR latex as the binder, based on 100 pts.mass of the pigment. The white paper gloss at 75° on the surface of the pigment-coated paper is not less than 60%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pigment-coated paper for printing. More specifically, the present invention relates to a pigment-coated paper for gloss printing that is excellent in offset printing suitability and suitable for hybrid printing having high-speed inkjet printer recording suitability.

  Offset printing has become the mainstream of printed matter manufacturing methods because high-speed and large-volume printing is possible. On the other hand, with the development of inkjet recording technology in recent years, variable data such as coupons, lucky numbers, bar codes, QR codes, etc. are printed in monochrome on addressed printing in the direct marketing field or printed matter that pre-prints fixed data using the full-color offset printing method. Increasingly, so-called hybrid printing, in which additional printing is performed by an ink jet printer, is performed.

As the pigment-coated paper for printing used in offset printing, there are usually those described in JP-A-7-189179 (Patent Document 1). The coated paper is usually produced by applying a coating layer coating containing pigment, binder, etc. at least 10 g / m ² per side of the base paper using various coaters, and then calendering to smooth the surface. Has been.

  Since these general coated papers mainly focus on printing process suitability, they have a pigment coating layer strength that does not generate picking or blistering in offset printing, but have poor ink-jet ink absorbability.

  As a printing paper suitable for both offset printing and inkjet recording, a method of providing a layer containing a pigment mainly composed of silica on a base paper (Japanese Patent Laid-Open No. 2002-127487, Patent Document 2) has been proposed. By using silica in the pigment coating layer, the ink-jet ink absorbability is improved, but since it does not cause picking during offset printing, it is necessary to use a large amount of binder components, so the gloss of the pigment coated paper surface is reduced. In addition, the texture of gloss printing paper cannot be obtained, and the use of silica increases the manufacturing cost and greatly exceeds the cost of general gloss printing paper, so it is not accepted by the market. .

  In addition, a cationic resin having a specific structure is coated on the base paper in advance, and a pigment coating layer mainly composed of light calcium carbonate is provided, and the specific absorption by the Bristow method (J. TAPPI No. 51-87) on the surface is provided. There has been proposed a coated paper for printing (Japanese Patent Application Laid-Open No. 2004-84141, Patent Document 3) in which the amount of ink transferred over time is defined. However, even with this method, the surface of the pigment-coated paper cannot obtain a high glossiness, and the texture of gloss printing paper cannot be obtained.

  Further, at least two coating layers are provided on the base paper, the base paper adjacent layer contains a pigment having a specific shape, and the surface layer contains thermoplastic organic fine particles having a specific glass transition temperature. Thus, by generating cracks on the surface and improving the air permeability of the coating layer, blisters during offset printing and electrophotographic recording can be prevented, and use as ink jet paper (Japanese Patent Laid-Open No. 2005-36379, Patent Document) 4) has also been proposed. However, since the viscosity of inkjet ink is much lower than the viscosity of offset printing ink and the heat melting viscosity of electrophotographic toner, if there are many cracks on the paper surface, the ink bleeds along the cracks. A feathering phenomenon occurs and satisfactory print image quality cannot be obtained. Therefore, the present situation is that a pigment-coated paper for printing having a surface strength capable of offset printing and ink jet recording suitability and a high surface glossiness has not been obtained.

JP-A-7-189179 (first item) Japanese Patent Laid-Open No. 2002-127487 (first item) JP 2004-84141 A (Section 6) Japanese Patent Laying-Open No. 2005-36379 (first item)

  An object of the present invention is to provide a gloss-based pigment-coated paper suitable for hybrid printing having excellent offset printing suitability and high-speed inkjet printer recording suitability.

  The present invention includes the following modes.

  The pigment-coated paper for printing according to the present invention is provided with at least two pigment-coated layers on at least one surface of a base paper, and the pigment-coated layer has an outermost layer of 100 parts by weight of pigment in kaolin. Is contained in an amount of 4 to 10 parts by mass with respect to 100 parts by mass of the styrene / butadiene copolymer latex as a binder, and an inner coating layer provided between the outermost layer and the base paper, In 100 parts by mass of pigment, 50 to 90 parts by mass of light calcium carbonate having an average particle size of 0.05 to 0.8 μm and 10 to 25 parts by mass of organic or inorganic pigment having an average particle size of 1.0 to 5.0 μm And 10 to 30 parts by mass of a styrene / butadiene copolymer latex as a binder with respect to 100 parts by mass of the pigment, and a white paper glossiness (JIS-P) at 75 degrees on the surface of the pigment-coated paper. 8142) is 60% or more.

The inorganic pigment is preferably heavy calcium carbonate. Moreover, it is preferable that the said white paper glossiness is 70% or more, and it is preferable to contain 3-15 mass parts of hollow plastic pigments with respect to 100 mass parts of pigments in the said outermost layer. Further, the density of the printing pigment-coated paper is preferably 0.95 to 1.15 g / cm ³ .

  According to the present invention, a pigment-coated paper for gloss-based printing suitable for hybrid printing having excellent offset printing suitability and high-speed inkjet printer recording suitability can be obtained.

  The present invention will be described in detail below. The pigment-coated paper for printing according to the present invention is provided with at least two pigment-coated layers on at least one surface of a base paper, and the outermost layer of the pigment-coated layer has a specific pigment composition and binder composition, The inner coating layer provided between the outermost layer and the base paper contains a pigment having a specific average particle size and a binder.

  In order to obtain a coated paper having both offset printing suitability and high-speed inkjet ink absorption and high surface gloss, the present inventors make the pigment coating layer multi-layered and share the function of each layer. It was found that it can be achieved.

  The outermost layer contains 50 parts by mass or more of kaolin in 100 parts by mass of the pigment, and contains 4 to 10 parts by mass of styrene / butadiene copolymer latex as a binder with respect to 100 parts by mass of the pigment. In order to obtain a high surface, processing under a wide range of smoothing processing conditions became possible. As a result, high ink-jet ink absorbability and high ink solvent permeability were obtained.

  Examples of kaolin used in the outermost layer include kaolin of each grade, calcined kaolin, structural kaolin, deramikaolin and the like. As the average particle diameter of kaolin, fine particle kaolin of about 1 μm or less is preferable in terms of high glossiness and image quality in offset printing. Kaolin is contained in an amount of 50 parts by mass or more in 100 parts by mass of the pigment contained in the outermost layer, and more preferably 60 parts by mass or more. When the amount is less than 50 parts by mass, a sufficient gloss expression effect may not be obtained, which is not preferable.

  In the outermost layer, a pigment other than kaolin can be used in combination. Specific examples thereof include, for example, heavy calcium carbonate, light calcium carbonate, aggregated calcium carbonate, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, alumina, magnesium carbonate, magnesium oxide, silica, fine particle silica, colloidal silica. , Magnesium aluminosilicate, particulate calcium silicate, particulate magnesium carbonate, white carbon, satin white, bentonite, zeolite, sericite, smectite and other pigments, polystyrene resin, styrene / acrylic copolymer resin, urea resin , Melamine resin, acrylic resin, vinylidene chloride resin, benzoguanamine resin, and organic pigments composed of these fine hollow particles and through-hole organic materials.

  As an inorganic pigment used in combination with kaolin, light calcium carbonate is preferred because it is easy to obtain high gloss after smoothing treatment, and its shape is more preferably spindle-shaped or needle-shaped, needle-shaped Most preferred. As the organic pigment, it is preferable to use 3 to 15 parts by mass of a hollow plastic pigment in 100 parts by mass of the pigment. When the amount is less than 3 parts by mass, a remarkable combined effect may not be obtained. Moreover, when it mix | blends more than 15 mass parts, surface strength may fall and it may interfere with offset printing.

  The outermost layer contains 4 to 10 parts by mass of styrene / butadiene copolymer latex with respect to 100 parts by mass of the pigment. When the content is less than 4 parts by mass, it is not preferable because sufficient surface strength cannot be obtained and the offset printing may be hindered. On the other hand, when the amount exceeds 10 parts by mass, not only the ink-jet ink absorptivity is lowered but also the glossiness is lowered, which is also not preferable. In the outermost layer, a binder other than the styrene / butadiene copolymer emulsion may be used in combination.

  Examples of binders used in combination include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic. Acid copolymer salt, styrene / acrylic acid copolymer salt, urea resin, melamine resin, amide resin, acrylic resin latex, polyurethane latex, styrene, acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, acrylamide , Vinyl polymers and copolymers such as methacrylamide and methyl vinyl ether, synthetic rubber latex such as methyl methacrylate and butadiene resin, polyurethane resin, polyester resin, polyamide resin, Fin-maleic acid resins, melamine resins, and the like. Of these, various starches that have a small reduction in glossiness and that have an effect of improving coating suitability are preferably used.

  The inner coating layer provided between the outermost layer and the base paper has 50 to 90 parts by weight of light calcium carbonate having an average particle diameter of 0.05 to 0.8 μm and an average particle diameter of 100 parts by weight of the pigment. 10 to 25 parts by mass of an organic or inorganic pigment (hereinafter referred to as “organic or inorganic pigment”) of 1.0 to 5.0 μm is contained, and a styrene / butadiene copolymer latex is used as a binder with respect to 100 parts by mass of the pigment. By containing 10 to 30 parts by mass, the gap between the pigment particles is increased, and both the high solvent absorption speed of the inkjet ink and the surface strength necessary for offset printing can be achieved. Further, by adding the organic or inorganic pigment, the suitability of the outermost layer by the post-metering coating method such as the blade coating method or the Mayer bar method is improved, and better surface quality can be obtained.

  The light calcium carbonate used for the inner coating layer can be selected from those having a specific average particle size among those used in the outermost layer. In addition, pigments other than light calcium carbonate can be used in combination, and are appropriately selected from those used in the outermost layer.

  The light calcium carbonate used for the inner coating layer contains 50 to 90 parts by mass, more preferably 60 to 90 parts by mass, and most preferably 70 to 90 parts by mass. A light calcium carbonate content of less than 50 parts by mass is not preferable because sufficient solvent absorbability of the inkjet ink cannot be obtained. Even when the amount of light calcium carbonate used exceeds 90 parts by mass, the amount of the organic or inorganic pigment used decreases, making it difficult to obtain the effects of the present invention.

  The organic or inorganic pigment can also be appropriately selected from those listed in the specific examples on the outermost layer. Among them, heavy calcium carbonate is effective for improving the solvent absorption rate of ink-jet ink and for improving coating suitability. In terms of surface. When the average particle size of the organic or inorganic pigment is less than 1.0 μm, the difference from the average particle size of the combined pigment becomes small, and the satisfactory effect of improving the solvent absorption rate of ink-jet ink and the improvement of coating suitability are obtained. It may not be obtained.

  Further, when the average particle diameter of the organic or inorganic pigment exceeds 5.0 μm, surface glossiness after coating of the outermost layer may be hindered. To obtain the desired surface glossiness, smoothing treatment conditions It is necessary to increase the calendering pressure, which is undesirable because the solvent absorption rate of the inkjet ink may decrease as a result. As an average particle diameter of the said organic or inorganic pigment, 1.0-3.0 micrometers is more preferable, and 1.0-2.0 micrometers is further more preferable.

  The organic or inorganic pigment is used in an amount of 10 to 25 parts by mass. When the amount used is less than 10 parts by mass, a satisfactory effect of improving the solvent absorption rate of ink-jet ink and an effect of improving coating suitability may not be obtained. When the amount used exceeds 25 parts by mass, the solvent absorption rate of the ink-jet ink may decrease, and the ink-jet suitability may decrease. The amount of the organic or inorganic pigment used is more preferably 10 to 20 parts by mass.

  Further, the inner coating layer contains 10 to 30 parts by mass of styrene / butadiene copolymer latex with respect to 100 parts by mass of the pigment. When the content of the styrene / butadiene copolymer latex is less than 10 parts by mass, sufficient surface strength cannot be obtained, and offset printing may be hindered. Moreover, when it exceeds 30 mass parts, the solvent absorptivity of an inkjet ink may fall. In addition, a binder other than the styrene / butadiene copolymer can be used in combination, and as a specific example, it can be appropriately selected from those used in the outermost layer.

  In each coating layer, various auxiliary agents such as surfactants, pH regulators, viscosity modifiers, softeners, gloss imparting agents, waxes, dispersants, flow modifiers, stabilizers, antistatic agents , A crosslinking agent, a sizing agent, a fluorescent brightening agent, a colorant, an ultraviolet absorber, an antifoaming agent, a water-resistant agent, a plasticizer, a lubricant, an antiseptic, and a fragrance are appropriately included as necessary. May be.

As for the coating amount of the outermost layer of this invention, 6-30 g / m < ² > is preferable. When the coating amount is less than 6 g / m ² , the glossiness cannot be optimized because sufficient coating cannot be performed. On the other hand, when the amount is more than 30 g / m ² , the operability is deteriorated, for example, the drying property at the time of coating is deteriorated, and the production cost may be increased. A more preferable coating amount is 6 to 12 g / m ² .

As for the coating amount of the said inner side coating layer of this invention, 6-30 g / m < ² > is still preferable. In particular, in the case of the inner coating layer in contact with the base paper, if the coating amount is less than 6 g / m ² , it is difficult to fill the unevenness of the base paper, and glossiness may be lowered. When the amount is more than 30 g / m ² , the operability may be lowered and the production cost may be increased, for example, the drying property at the time of coating is deteriorated. A more preferable coating amount is 8 to 15 g / m ² .

  As a coating method for forming each coating layer, generally, conventional coating apparatuses such as a blade coater, an air knife coater, a roll coater, a reverse roll coater, a bar coater, a curtain coater, a slot die coater, a gravure coater, and a Chanplex are used. Coating apparatuses such as a coater, a brush coater, a two-roll type or metering blade type size press coater, a bill blade coater, a short dwell coater, and a gate roll coater can be appropriately used. Among these, blade coaters that can apply high-concentration paints at high speeds can suppress the penetration of the binder resin of the coating layer into the base paper, so that both the ink-jet ink absorbency and surface strength can be achieved with the amount of binder resin used. This is preferably used because it is easy to obtain a coated layer, and it is easy to obtain a highly glossy pigment coating layer surface having excellent surface properties.

  About the pulp which comprises the base paper in this invention, in the range which does not impair the effect of this invention, there is no limitation in the manufacturing method, a kind, etc. in particular. For example, chemical pulp such as KP, mechanical pulp such as SGP, RGP, BCTMP and CTMP, waste paper pulp such as deinked pulp, and non-wood pulp such as kenaf, bamboo, straw, hemp, etc. Organic synthetic fibers such as polyamide fibers and polyester fibers, recycled fibers such as polynosic fibers, and inorganic fibers such as glass fibers, ceramic fibers, and carbon fibers can also be used in combination. In addition, it is preferable to use chlorine free pulp, such as ECF pulp and TCF pulp, as the pulp used for the base paper.

  The beating degree of the pulp constituting the base paper is not particularly limited, but is preferably adjusted in the range of 300 to 550 cc (CSF), for example. When the beating degree exceeds 550 cc (CSF), since the entanglement and adhesive strength of the fibers are insufficient, satisfactory internal strength cannot be obtained, and blisters may occur during offset printing. On the other hand, if it is less than 300 cc (CSF), the effect of improving the adhesion due to the entanglement of the fibers is saturated, and conversely, the printing strength may be reduced due to the influence of the single fiber strength reduction. More preferably, it is 350-520cc (CSF).

  In the base paper, a binder, a dry paper strength enhancer, and a wet paper strength enhancer can be used in combination as long as the effects of the present invention are not impaired. Examples of the binder include water-soluble polymers such as various starches, polyvinyl alcohol, and carboxymethyl cellulose. Examples of the dry paper strength enhancer include anionic, cationic, or amphoteric polyacrylamide resins. Examples of the wet paper strength enhancer include polyamide resins, melamine / formaldehyde resins, urea / formaldehyde resins, polyamide / polyamine / epichlorohydrin resins, and polyethyleneimine resins.

  In the present invention, the sizing degree of the base paper is not particularly limited, but is generally adjusted to a Steecht sizing degree of about 100 seconds or less. As a method for adjusting the sizing degree, the internal sizing agent contained in the raw material and the surface sizing agent applied by a size press coater are adjusted individually or appropriately in combination to a predetermined sizing degree. As internal sizing agents, sizing agents such as rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, alkyl ketene dimers, and alkenyl succinic anhydride neutral sizing agents can be used. A suitable sizing agent and fixing agent are used in combination. Examples of the surface sizing agent include styrene / maleic acid copolymer, styrene / acrylic acid copolymer, styrene / methacrylic acid copolymer, etc. in addition to those used in the above-mentioned internal sizes. It is not something.

  Moreover, a filler may be blended in the base paper as necessary. As the filler, various pigments generally used for fine paper can be used, such as kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, magnesium carbonate, magnesium oxide, Mineral pigments such as silica, white carbon, bentonite, zeolite, sericite and smectite, as well as fine hollow particles, solid particles and polystyrene resins, urea resins, melamine resins, acrylic resins and vinylidene chloride resins Examples thereof include organic pigments such as through-hole particles.

  In addition, when making the base paper, in addition to pulp fibers and fillers, various anionic, nonionic, and cationic properties that have been used in the past are within the range that does not impair the desired effect of the present invention. Alternatively, various papermaking internal additives such as amphoteric yield improver and freeness improver can be appropriately selected and used as necessary. Furthermore, internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be added as necessary.

  There is no particular limitation on the paper making method of the base paper. For example, an acidic paper making method in which the paper making pH is around 4.5, an alkaline filler such as calcium carbonate is contained as a main component, and the paper making pH is from about 6 to about the paper making pH. All paper making methods such as neutral paper making method with 9 weak alkalinity can be applied, and long paper machine, twin wire paper machine, round net paper machine, Yankee paper machine etc. are used as appropriate can do.

  The pigment-coated paper for printing of the present invention is one in which each pigment-coated layer is provided and then subjected to a smoothing treatment to develop surface gloss. As a smoothing processing method, a normal smoothing processing device such as a super calendar, a gloss calendar, a soft calendar, or the like is used. The smoothing process may be appropriately performed on-machine or off-machine, and the form of the pressure device, the number of pressure nips, heating, and the like are appropriately adjusted according to a normal smoothing device. As various physical properties of the pigment coated paper for printing after the smoothing treatment, the blank paper glossiness (JIS-P8142) at 75 degrees on the surface is preferably 60% or more, and more preferably 70% or more. When the glossiness of the blank paper is less than 60%, the ink gloss after the offset printing is also low, and a printed matter that is satisfactory as a gloss printing paper cannot be obtained, which is not preferable.

Moreover, it is preferable that the density as a pigment coated paper for printing is 0.95-1.15 g / cm < ³ >. If the density is less than 0.95 g / cm ³ , sufficient printing strength may not be obtained, and if it exceeds 1.15 g / cm ³ , the ink-jet ink absorption capacity cannot be ensured. Ink jet ink absorbability may not be obtained.

  In the present invention, the method for producing a hybrid printed material is not particularly limited. For example, fixed information can be created by printing variable information with an inkjet printer after printing it with an offset printer, but offset printing can also be performed after variable information is recorded with an inkjet printer first. Both of them can be online or offline, and the paper form can be created by either plain or winding.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. In the examples, “parts” and “%” are parts by mass and mass% unless otherwise specified.

Example 1
[Manufacture of base paper]
90 parts by mass of LBKP (CSF freeness 450 ml), 10 parts by mass of NBKP (CSF freeness 450 ml), and 0.05 mass of alkenyl succinic anhydride (trade name: Fibran 81, manufactured by National Starch) as an internal sizing agent Part, 0.2 part by mass of polyacrylamide resin (trade name: PS194-7, manufactured by Arakawa Chemical Industries) and 0.6 part by mass of sulfuric acid band are added as a paper strength enhancer, and these mixtures are diluted with white water. A paper stock having a pH of 5.3 and a solid content concentration of 1.1% was prepared. This stock is subjected to a papermaking machine to make a paper, and the obtained wet paper has 0.2 parts of a styrene / maleic acid copolymer (trade name: Polymeralon 385, manufactured by Arakawa Chemical Industries), oxidized starch ( A size press liquid containing 5.5% concentration of product name: Ace A (manufactured by Oji Cornstarch Co., Ltd.) is applied with a size press apparatus so that the applied amount is 2 g / m ² in terms of dry mass, dried, and further A smoothing process was performed using a machine calendar to obtain a base paper having a basis weight of 88 g / m ² .

[Preparation of coating solution for inner coating layer]
Light calcium carbonate 65% dispersion (trade name: YCC-FD, average particle size 0.6 μm, manufactured by Yabashi Kogyo Co., Ltd.) 130 parts by mass, heavy calcium carbonate 70% dispersion 22 having an average particle size of 1.2 μm 22 .1 part by mass of 10 parts by mass of 20% aqueous solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch) and 24 parts by mass of 50% dispersion of SBR latex (trade name: T-2531H, manufactured by JSR) The mixture was added and stirred, and water was further added to prepare a coating solution having a solid content of 60%.
[Preparation of coating solution for outermost layer]
70 parts by weight of water, kaolin (trade name: Hydra Gloss 90, manufactured by Huber) and 60 parts by weight of acicular light calcium carbonate dispersion (trade name: Tama Pearl TP-123CS, manufactured by Okutama Kogyo Co., Ltd.) as a dispersant Add 0.1 parts by mass of 40% aqueous solution of sodium polyacrylate (trade name: Aron T-50, manufactured by Toa Gosei Co., Ltd.) and disperse in water using a Coreless disperser to prepare a pigment slurry with a solid content of 70% did. To this pigment slurry, 15 parts by mass of 20% aqueous solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch) and 12 parts by mass of 50% dispersion of SBR latex (trade name: T-2531H, manufactured by JSR) were added. The mixture was stirred and water was further added to prepare a coating solution having a solid concentration of 60%.

[Formation of inner coating layer]
The inner coating layer coating solution was applied to both sides of the base paper using a blade coater so that the dry coating amount per side was 10 g / m ² to form an inner coating layer.
[Formation of outermost layer]
The outermost layer coating solution is applied onto the inner coating layer formed on both surfaces of the base paper using a blade coater so that the dry coating amount per side is 10 g / m ^2. A pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained.

Example 2
In the preparation of the coating solution for the outermost layer in Example 1, instead of 50 parts by mass of a 60% dispersion of acicular light calcium carbonate (trade name: Tamapearl TP-123CS, manufactured by Okutama Kogyo Co., Ltd.), spindle-shaped light calcium carbonate A pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained in the same manner as in Example 1 except that 45 parts by mass of a 67% dispersion (trade name: Tamapearl TP-221GS, manufactured by Okutama Kogyo Co., Ltd.) was used. .

Example 3
In the preparation of the outermost layer coating liquid of Example 1, the amount of kaolin used was reduced from 70 parts by weight to 55 parts by weight, and the acicular light calcium carbonate 60% dispersion was increased from 50 parts by weight to 75 parts by weight. Except for the above, a pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained in the same manner as in Example 1.

Example 4
In the preparation of the outermost layer coating liquid of Example 1, the same procedure as in Example 1 was conducted except that 20 parts by mass of a 26% dispersion of a hollow plastic pigment (trade name: AE-852, manufactured by JSR) was added. Thus, a pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained.

Example 5
In the preparation of the outermost layer coating liquid of Example 1, the basis weight was 128 g / m ^{2 in the same} manner as in Example 1 except that the amount of the 50% dispersion of SBR latex was increased from 12 parts by mass to 20 parts by mass. A pigment-coated paper for printing was obtained.

Example 6
In the preparation of the coating liquid for the inner coating layer of Example 1, Example was used except that heavy calcium carbonate having an average particle diameter of 2.5 μm was used instead of heavy calcium carbonate having an average particle diameter of 1.2 μm. In the same manner as in Example 1, a pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained.

Example 7
In the preparation of the coating solution for the inner coating layer of Example 1, Example 1 was used except that heavy calcium carbonate having an average particle size of 4.7 μm was used instead of heavy calcium carbonate having an average particle size of 1.2 μm. In the same manner as in Example 1, a pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained.

Example 8
In the formation of the inner coating layer of Example 1, the basis weight of 120 g / m is the same as that of Example 1 except that the coating amount after drying of the inner coating layer coating solution is reduced to 6 g / m ² per side. A m ² printing pigment coated paper was obtained.

Comparative Example 1
In the preparation of the outermost layer coating liquid of Example 1, the amount of kaolin used was reduced from 70 parts by weight to 40 parts by weight, and the acicular light calcium carbonate 60% dispersion was increased from 50 parts by weight to 100 parts by weight. Except for the above, a pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained in the same manner as in Example 1.

Comparative Example 2
In the preparation of the outermost layer coating liquid of Example 1, the basis weight was 128 g / m ^{2 in the same} manner as in Example 1 except that the amount of the 50% dispersion of SBR latex was increased from 12 parts by mass to 30 parts by mass. A pigment-coated paper for printing was obtained.

Comparative Example 3
In the preparation of the coating solution for the inner coating layer of Example 1, instead of 130 parts by mass of a 65% dispersion of light calcium carbonate (trade name: YCC-FD, manufactured by Yabashi Kogyo Co., Ltd.), the average particle size is 1. A pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained in the same manner as in Example 1 except that 120.7 parts by weight of a 70% dispersion of 2 μm heavy calcium carbonate was used.

Comparative Example 4
In the preparation of the coating solution for the inner coating layer of Example 1, the basis weight of 128 g / s was the same as in Example 1 except that the amount of the 50% dispersion of SBR latex was reduced from 24 parts by mass to 12 parts by mass. A m ² printing pigment coated paper was obtained.

Comparative Example 5
In the preparation of the coating solution for the inner coating layer of Example 1, 70% heavy calcium carbonate having an average particle size of 0.6 μm was used instead of the 70% dispersion of heavy calcium carbonate having an average particle size of 1.2 μm. A pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained in the same manner as in Example 1 except that the% aqueous dispersion was used. A streak defect was observed on the outermost coated surface.

Comparative Example 6
In the preparation of the coating liquid for the inner coating layer of Example 1, 70 of heavy calcium carbonate having an average particle diameter of 6.0 μm instead of 70% dispersion of heavy calcium carbonate having an average particle diameter of 1.2 μm. A pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained in the same manner as in Example 1 except that the% aqueous dispersion was used.

Comparative Example 7
In the preparation of the inner coating layer coating solution of Example 1, the amount of light calcium carbonate 65% dispersion (trade name: YCC-FD, manufactured by Yabashi Kogyo Co., Ltd.) was 146 parts by mass, and the average particle size was A pigment-coated paper for printing having a basis weight of 128 g / m ² was obtained in the same manner as in Example 1 except that the amount of the 70% dispersion of 1.2 μm heavy calcium carbonate was changed to 7.3 parts by mass. . In addition, the streak defect was recognized by the outermost layer coating surface.

Comparative Example 8
In the preparation of the coating liquid for the inner coating layer of Example 1, the amount of light calcium carbonate 65% dispersion (trade name: YCC-FD, manufactured by Yabashi Kogyo Co., Ltd.) was 107.7 parts by mass, and the average A printing pigment coated paper having a basis weight of 128 g / m ² was obtained in the same manner as in Example 1 except that the amount of heavy calcium carbonate 70% dispersion having a particle size of 1.2 μm was changed to 42.9 parts by mass. Obtained.

For the pigment-coated paper for printing obtained in the examples and comparative examples, the processing conditions were set so that the white paper glossiness (JIS-P8142) at 75 degrees of the surface was 73 to 77% using a super calender. It adjusted and the smoothing process was performed.
The following evaluation was performed on the obtained pigment-coated paper for printing, and the results are shown in Table 1.

[Evaluation methods]
[Measurement of surface gloss of coating layer]
The surface gloss of the obtained pigment-coated paper was measured at an incident angle of 75 degrees according to JIS P-8142 using a gloss meter (described in JIS-Z8741).

[Calculation of density of pigment coated paper for printing]
The thickness of the obtained pigment coated paper was measured using a thickness meter (based on JIS P-8118), and the density was calculated from the thickness and basis weight.

[Evaluation of offset printability on coating layer surface]
(Dry pick strength)
Using a RI printing machine (RI-1, manufactured by Ishikawajima Sangyo Machinery Co., Ltd.), perform solid printing with a test ink (SD50 Red BT-13 for Best One Paper Test, manufactured by T & K TOKA) to pick the printed surface. The degree was visually determined. 5 is the best in the 5-level evaluation, 1 is the worst level, and 3 is the allowable limit.
(Wet pick strength)
In the dry pick strength test method, wet pick strength was evaluated in the same manner as in the dry pick strength test method, except that water was adhered to the surface of each coated pigment-coated paper with a water adhesion roll before printing.

[Evaluation of inkjet ink absorption speed]
(1) The obtained pigment-coated paper is set in an oil absorption meter automatic type (JIS P-8130, manufactured by Kumagaya Riki Kogyo Co., Ltd.).
(2) A cellophane tape is affixed to the upper part of the set test piece, and 5 μl of Kodak Versamark DS6240 printing system ink (No. 1007) is put on the cellophane tape using a microsyringe.
(3) After passing the metal roller over the ink, the time until the glossiness of the stretched ink surface disappeared was visually judged to evaluate the ink jet ink absorption speed.
In general, it was determined that what dried within 5 seconds had suitability for an actual printer.

As clearly shown in Table 1, when the smoothing treatment is performed so that the glossiness of the blank paper is about 75%, the printing pigment coated paper according to the present invention has excellent printing strength both in dry and wet conditions. And has aptitude for offset printing. In addition, since the density of the pigment-coated paper for printing is in the range of 0.95 to 1.15 g / cm ³ , the pigment-coated paper for printing having high ink-jet ink absorbency and excellent suitability as hybrid printing paper is used. Obtained (Examples 1-8). However, when the formulation for the outermost layer and the formulation for the inner coating layer deviate from the provisions of the present invention, pigment coated papers suitable for hybrid printing applications were not obtained (Comparative Examples 1 to 8).

  INDUSTRIAL APPLICABILITY The present invention provides a gloss-based pigment coated paper for hybrid printing that is excellent in offset printing suitability and also has high-speed inkjet printer recording suitability, and is extremely useful in practice.

Claims (5)

In a pigment coated paper for printing in which at least two pigment coated layers are provided on at least one surface of a base paper, the pigment coated layer has an outermost layer of 100 parts by mass of pigment and 50 parts by mass of kaolin. 4 to 10 parts by mass of a styrene / butadiene copolymer latex as a binder with respect to 100 parts by mass of the pigment, and the inner coating layer provided between the outermost layer and the base paper is 100 parts by mass of the pigment. Medium containing 50 to 90 parts by weight of light calcium carbonate having an average particle diameter of 0.05 to 0.8 μm and 10 to 25 parts by weight of an organic or inorganic pigment having an average particle diameter of 1.0 to 5.0 μm as a binder 10 to 30 parts by mass of styrene / butadiene copolymer latex with respect to 100 parts by mass of pigment, and white paper glossiness at 75 degrees of the pigment coated paper surface (JIS-P814) A pigment-coated paper for printing, wherein 2) is 60% or more. The printing pigment-coated paper according to claim 1, wherein the inorganic pigment is heavy calcium carbonate. The pigment-coated paper for printing according to claim 1 or 2, wherein the glossiness of the white paper is 70% or more. The pigment-coated paper for printing according to claims 1 to 3, wherein the outermost layer contains 3 to 15 parts by mass of a hollow plastic pigment with respect to 100 parts by mass of the pigment. The printing pigment-coated paper according to claim 1, wherein the density of the printing pigment-coated paper is 0.95 to 1.15 g / cm ³ .