JP2006328595A - Coated paper for printing use and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide coated paper for printing use excellent in white paper gloss and surface smoothness and printability as well despite having been coated with a coating liquid by a film transfer system hardly affording good surface smoothness, and to provide a method for producing the coated paper. <P>SOLUTION: The coated paper for printing use is such that at least one side of base paper is provided with a coating layer comprising a pigment and an adhesive. For the coating layer, the pigment is 2.0-3.5 μm in average particle size d50<SB>1</SB>determined by light scattering system, being 0.20-0.55 μm in average particle size d50<SB>2</SB>determined by sedimentation system, wherein the ratio(d50<SB>1</SB>/d50<SB>2</SB>) is ≥4. The pigment contains delaminated kaolin ≥95% in the mass distribution of ≤2 μm particles and 35-50% in the mass distribution of ≤0.3 μm particles in the particle size distribution curve determined by sedimentation system, and the delaminated kaolin accounts for 20-100 mass% of the whole pigment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coated paper for printing having a coating layer coated by a film transfer method, excellent in surface smoothness and white paper gloss containing a specific delaminated kaolin, and excellent in printability such as printing smoothness and the like. It relates to a manufacturing method.

In general, coated paper for printing is manufactured by coating and drying a coating liquid mainly composed of a pigment and an adhesive on a base paper, and depending on the coating amount of the coating liquid and the finishing method of the coated paper, it can be cast coated. It is classified into paper, art paper, coated paper, finely coated paper, and the like. These coated papers are subjected to multicolor printing or single color printing, and are widely used as commercial printed materials such as flyers, brochures and posters, or as publications such as books and magazines. In recent years, with the progress of visualization and colorization of printed materials, there has been an increasing demand for higher quality coated paper for printing. Printing of blank paper quality such as blank paper glossiness, smoothness, whiteness, and printing smoothness, etc. Quality such as appearance in the finish is regarded as important.
In particular, leaflets, pamphlets and the like among commercial printed materials have been required to have low cost and good print finishes for the purpose of advertising media. Therefore, the paper used is also becoming thinner and lighter.

Conventional coated paper manufacturing methods include the off-machine method, in which papermaking and coating are performed in separate processes, and the on-machine method, in which papermaking and coating are performed simultaneously on a single machine. More efficient production is possible. Therefore, in general, an on-machine method is adopted as an equipment for producing lightweight coated paper, and after paper making, a pigment coating solution is applied to a film transfer type gate roll or rod or blade metering size press coater, fountain. It is produced by the short dwell blade coater that is a method.
The film transfer method is capable of simultaneous coating on both sides and requires less capital investment than the blade method, and is an advantageous means for producing thin and lightweight coated papers that require low costs.

  Conventionally, various methods for providing a pigment coating layer by a film transfer method have been proposed (Patent Documents 1, 2, 3, 4, 5). These mainly disclose means for solving mist and paint gum-up occurring at a coating speed of 1100 m / min or more. Also, a paint for film transfer coating (Patent Document 6) that exhibits excellent gloss and smoothness comparable to blade coating has been introduced. This is characterized by the use of a low-viscosity starch-based adhesive and the concentration of the pigment coating solution being as high as 58% or more, but because the starch-based adhesive used is low in viscosity, After application by the film transfer method, the starch-based adhesive may migrate in the coating layer, which may cause uneven printing.

Conventionally, delaminated kaolin has been used as the pigment used in the pigment coating layer, and coated papers containing specific delaminated kaolin such as aspect ratio and particle diameter (Patent Documents 7 to 9) are proposed. Has been. All of them are intended to obtain a dull or matte coated paper that uses a delaminated kaolin with a relatively large particle size and suppresses the glossiness of the blank paper. It is not done.
In addition, a coating liquid containing 50 parts by weight or more of an inorganic pigment having a pigment particle diameter ratio (laser method / precipitation method) measured by a laser method and a precipitation method in the range of 3.0 to 10 parts by weight, There has been proposed a coated paper for offset printing (Patent Document 10) coated on a base paper by a film transfer method.
However, according to the study by the present inventors, when trying to obtain a lightly coated coated paper using the kaolin specifically disclosed in the examples, the coating having a sufficient blank gloss is not necessarily obtained. It was found that no paper was obtained.

Japanese Patent No. 3143899 Japanese Patent No. 2967723 Japanese Patent No. 2910030 Japanese Patent No. 3328554 Japanese Patent No. 3328922 Japanese Patent No. 2737897 JP-A-11-302998 JP 2002-105889 A JP 2002-194698 A JP 2005-89868 A

  In the present invention, a coating liquid containing a specific delaminated kaolin is applied by a film transfer method to provide white paper gloss, surface smoothness, and ink suitability such as ink deposition, print smoothness, and surface print strength. An excellent coated paper and a method for producing the same are provided.

The printing coated paper of the present invention is a printing coated paper in which a coating layer mainly composed of a pigment and an adhesive is provided on at least one side of a base paper, wherein the coating layer is used as a pigment by a light scattering method. the average particle size d50 ₁ which measured is in the range of 2.0～3.5Myuemu, the average particle diameter d50 ₂ as measured by sedimentation method is in the range of 0.20～0.55Myuemu, the average particle diameter of the d50 ₁ and the average is the ratio of the particle diameter _{d50 2 (d50 1 / d50 2} ) is 4 or more, yet, in the particle size distribution measurement curve by sedimentation method, the mass distribution of particles smaller than 2μm is 95% or more, 0. It contains delaminated kaolin in which the mass distribution of particles of 3 μm or less is in the range of 35 to 50%, and the mass proportion of the delaminated kaolin in the pigment in the coating layer is 20 to 100% by mass Features Such a coating layer can be formed by coating by a film transfer method. In addition, in this invention, it is preferable to contain 2-25 mass parts of starch derivatives with respect to 100 mass parts of pigments, and it is still more preferable if content of this kaolin is 30-100 mass%.
Moreover, when 1-20 mass parts of copolymer latex whose particle diameter is 40-150 nm is contained as an adhesive agent with respect to 100 mass parts of pigments, printing strength will improve more.
Furthermore, the production method of the present invention for producing a coated paper for printing in which a coating layer mainly composed of a pigment and an adhesive is provided on at least one side of a base paper includes the following steps A and B:
Step A: as coated liquid, the average particle size d50 ₁ as measured by light scattering method is in the range of 2.0～3.5Myuemu, average particle diameter d50 ₂ as measured by sedimentation method from 0.20 to 0. Particles within the range of 55 μm, the ratio of the average particle diameter d50 ₁ to the average particle diameter d50 ₂ (d50 ₁ / d50 ₂ ) is 4 or more, and in the particle size distribution measurement curve by the sedimentation method, particles of 2 μm or less The delaminated kaolin has a mass distribution of 95% or more and a mass distribution of particles of 0.3 μm or less in the range of 35 to 50%, and the mass ratio of the delaminated kaolin in the pigment is 20 Preparing a dispersion of ~ 100% by weight;
Step B: a step of coating the coating solution prepared in Step A on at least one side of a base paper by a film transfer method, wherein a starch derivative is contained in the coating solution of the coating layer Is preferably contained in an amount of 2 to 25 parts by mass with respect to 100 parts by mass of the pigment, and more preferably a thickener or a water retention agent is incorporated when the amount of the starch derivative is small.

  The coated paper for printing according to the present invention is excellent in surface smoothness, white paper gloss, and printing suitability such as printing smoothness and ink inking property in coating by a film transfer method in which good surface smoothness is difficult to obtain. It has the characteristics.

Kaolin used in the present invention has an average particle size d50 ₁ as measured by light scattering method is in the range of 2.0～3.5Myuemu, average particle diameter d50 ₂ as measured by sedimentation method from 0.20 to 0 in the range of .55Myuemu, moreover, the average particle size d50 ₁ and an average particle diameter d50 ₂ ratio is at _(d50 1 / d50 ₂₎ is 4 or more, the particle size distribution measurement curve measured by sedimentation method, following 2μm It is necessary that the particles have a mass distribution of 95% or more and a delaminated kaolin in which the mass distribution of particles of 0.3 μm or less is in the range of 35 to 50%. When kaolin having such physical properties is applied to a base paper as a paint by a film transfer method, the pigment is uniformly applied to the surface of the base paper, and the covering property is remarkably improved. In the present invention, it is necessary that the content of the delaminated kaolin in the pigment is 20% or more, and it is more preferable that the content of the delaminated kaolin is 30 to 100% by mass. When the delaminated kaolin content is less than 20% by mass of the total pigment, the improvement in smoothness is insufficient.

Delaminated kaolin is a clay mineral obtained by peeling a layered bulk kaolin into a single layer, and has a large aspect ratio.
In general, the individual shape characteristics of tabular grains such as delaminated kaolin can be defined by the ratio (aspect ratio: d / t) to the major axis d thickness t. In the present invention, delaminated kaolin is used. particulate characteristics of a specified average particle diameter d50 ₂ by an average particle size d50 ₁ and sedimentation method using a light scattering method.
In the light scattering method average particle size d50 ₁ measurement by the contrast its diameter is regarded all individual particles to spherical particles are measured, the average particle size d50 ₂ measured by sedimentation method, particle shape sedimentation In order to affect the property, particles having a flat plate shape and slower sedimentation are measured as particles having a smaller apparent diameter. Thus, as the particle aspect ratio as described above is large, the average particle diameter d50 ₂ ratio by an average particle size d50 ₁ and sedimentation method using a light scattering _method, d50 1 / d50 ₂ is considered to increase. In the present invention, a laser diffraction particle size distribution analyzer SALD-2000 (manufactured by Shimadzu Corporation) is used as a method for measuring the average particle size by the light scattering method, and Cedigraph 5100 (as a method for measuring the average particle size by the sedimentation method). Micromeritics) was used.

Incidentally, in the particle size distribution of the delaminated kaolin measured by the sedimentation method, when the mass distribution of particles of 2 μm or less is less than 95% and the mass distribution of particles of 0.3 μm or less is less than 35%, a component having a large particle size is present. In many cases, it is not preferable because the smoothness of the coating layer is lowered. When the mass distribution of particles of 0.3 μm or less exceeds 50%, there are many components with small particle sizes, and the coating liquid using this pigment is contained in the base paper. It is not preferable because it penetrates excessively and reduces the smoothness of the coating layer.
The average particle size d50 _1, and an average particle diameter d50 ₂ is, when it is less than each less than 2.0μm and 0.20μm, since delaminated kaolin in coated liquid is excessively penetrates into the base paper It becomes difficult to form a coating layer with high smoothness. In addition, when the average particle diameter d50 ₁ and the average particle diameter d50 ₂ exceed 3.5 μm and 0.55 μm, respectively, it is difficult to obtain a coated paper having sufficient white paper gloss. Then, in the case of d50 1 _/ d50 ₂ is less than 4, it is difficult to obtain a coated paper for printing the present invention is contemplated. In the present invention, the value of d50 ₁ / d50 ₂ is preferably 5 to 9.5, more preferably 6 to 9.

In the present invention, the pigment component is composed of 20 to 100% by mass of the specific delaminated kaolin and other pigments of 80% by mass or less.
Examples of such other pigments include pigments used in the ordinary coated paper field, specifically, heavy or light calcium carbonate, kaolin (excluding the above specific delaminated kaolin), satin white, and calcined kaolin. , Inorganic pigments such as talc, calcium sulfate, barium sulfate, aluminum hydroxide, titanium dioxide, zinc oxide, alumina, magnesium carbonate, magnesium oxide, silica, magnesium aluminosilicate, calcium silicate, bentonite, zeolite, sericite, smectite, Organic pigments such as solid type, hollow type, through-hole type plastic pigments, binder pigments, etc. are listed. Depending on the target coated paper quality, one or more types can be selected and used. To do.

  In order to develop the surface strength of the coated paper of the present invention, a water-soluble adhesive or a water-dispersible adhesive is used. As the water-soluble adhesive, in addition to starch derivatives, proteins such as casein, soybean protein, and synthetic proteins, cellulose derivatives such as hydroxyethyl cellulose, polyvinyl alcohol and modified products thereof can be used. As the starch derivative, oxidized starch, esterified starch, dextrin, esterified starch, cold water-soluble starch, and the like can be used. Among these starches, oxidized starch having a molecular weight of about 3 to 50,000 is more preferable. The blending amount is preferably 2 to 25 parts by mass with respect to 100 parts by mass of the pigment. Incidentally, when the blending amount of the starch derivative is less than 2 parts by mass, when the coating liquid is transferred to the paper, the immobilization of the paint is accelerated, the paint is not efficiently transferred to the paper, the paint residue remains on the roll, and the roll becomes dirty. May occur. On the other hand, when the amount exceeds 25 parts by mass, the viscosity of the paint excessively increases, the separation of the paper at the application nip exit is not stable, and there is a possibility that unevenness having a certain pattern occurs on the paper surface.

  Examples of the water dispersible adhesive used in the present invention include conjugated diene copolymer latexes such as styrene-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex, and styrene-methyl methacrylate-butadiene copolymer latex. Acrylic polymer latex such as acrylic acid ester and / or methacrylic acid ester polymer or copolymer latex, vinyl polymer latex such as ethylene-vinyl acetate polymer latex, or carboxyl of these various polymer latexes Examples thereof include a polymer or a copolymer latex modified with a functional group-containing monomer such as a group, and among these copolymer latexes, those having an average particle diameter of 40 to 150 nm are preferable. With the same content, the smaller the average particle diameter of the latex, the larger the adhesion area with the pigment in the coating layer, and the strength of the coating layer can be effectively expressed. Incidentally, if the particle size of the copolymer latex is smaller than 40 nm, the wetted surface strength by dampening water at the time of offset printing is lowered due to the influence of the emulsifier compounded at the time of latex production, which is not preferable. Furthermore, when the particle diameter of the latex exceeds 150 nm, the contact strength with the pigment in the coating layer is reduced at the same content, so that the surface strength may be insufficient. The amount of the copolymer latex contained in the pigment coating solution can be selected in the range of 3 to 20 parts by mass, preferably 5 to 15 parts by mass with respect to 100 parts by mass of the pigment.

  In the present invention, 2 to 25 parts by weight of a starch derivative is used as an adhesive with respect to 100 parts by weight of a pigment in order to impart coating suitability during coating by a film transfer method and sufficient surface strength to the coated paper. It is desirable to use 3 to 20 parts by weight (preferably 5 to 15 parts by weight) of copolymer latex.

  When the coating liquid used for forming the coating layer in the coated paper of the present invention has only a low water retention performance, for example, even if the blending amount of the starch derivative is 2 parts by mass or more with respect to 100 parts by mass of the pigment When the coating liquid is transferred to the paper at the time of application, the moisture of the coating liquid is quickly absorbed by the paper, so that the coating liquid on the roll is solidified and cannot be peeled off from the roll, and the roll dirt May occur. In order to prevent this, it is preferable to contain a thickener or a water retention agent in the coating solution. As the thickener or water retention agent preferably used in the present invention, an alkali thickening type such as polycarboxylic acid or acrylic copolymer, an acrylic polymer or a hydrophilic base polymer such as polyethylene oxide is used at both ends. Naturally derived types such as an association type having an oil group, carboxymethylcellulose, sodium alginate and the like are included, and the blending amount is preferably in the range of 0.01 to 1.0 part by weight, more preferably 100 parts by weight of the pigment. Is in the range of 0.05 to 0.8 parts by mass.

  In addition to thickeners and water retention agents, the coating solution contains blue or purple dyes or colored pigments, fluorescent dyes, antioxidants, anti-aging agents, conductive inducers, Various auxiliaries such as a foaming agent, an ultraviolet absorber, a dispersant, a pH adjuster, a release agent, and a water repellent can be appropriately blended.

  In the present invention, the solid content concentration of the coating liquid containing the specific delaminated kaolin, other pigments used in combination as needed, an adhesive, and various auxiliary agents used as needed is 25. It can select in the range of -75 mass%. In consideration of adjustment of the coating amount and operability, it is desirable to be in the range of 40 to 65% by mass.

The dry coating amount of the coating layer in the coated paper of the present invention is preferably 0.5 to 20.0 g / m ² per side. Incidentally, when the coating amount is less than 0.5 g / m ² , the surface coverage of the paint is inferior, and the desired quality cannot be obtained. Moreover, exceeding 20.0 g / m < ² > is economically unpreferable.
In addition, the specific delaminated kaolin used in the present invention is a film transfer method, and a dry coating amount per side is about 12 g / m ² or less, and further, a light weight coating of about 10 g / m ² or less is applied. When producing coated paper for printing, a more remarkable effect is exhibited.

  The base paper used in the present invention is not particularly limited, and the base paper used in conventional coated paper for printing can be used.

Examples of pulp components that constitute such base paper include bleached chemical pulp such as bleached hardwood pulp (LBKP) and bleached softwood pulp (NBKP) that are commonly used, groundwood pulp (GP), and pressurized groundwood pulp (PGW). ), Refined groundwood pulp (RGP), thermomechanical pulp (TMP) and other mechanical pulp, deinked waste paper pulp (DIP), waste paper, and the like are appropriately mixed and used. The amount of mechanical pulp preferably does not exceed 70% by mass of the total pulp constituting the base paper. If it exceeds 70% by mass, the printability of the finally obtained coated paper, such as print smoothness and surface strength, may be impaired. Moreover, 1 type, or 2 or more types, such as a pulp fiber obtained from non-wood fiber raw materials, such as kenaf, a synthetic pulp, an inorganic fiber, can also be mix | blended with a base paper.
Mechanical pulp and deinked waste paper pulp can be bleached and used as necessary, and the degree of bleaching can be arbitrarily performed.
For bleaching pulp, it is preferable to use a bleaching process that does not use molecular chlorine such as chlorine gas or chlorine compounds such as chlorine dioxide from the viewpoint of environmental conservation. Pulp that has undergone such bleaching process is used. Examples thereof include ECF pulp and TCF pulp.

Examples of fillers added to the base paper include heavy calcium carbonate, light calcium carbonate, calcium sulfite, gypsum, talc, clay, calcined kaolin, white carbon, amorphous silica, delaminated kaolin, diatomaceous earth, and magnesium carbonate. Examples include inorganic pigments such as titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide, and organic pigments such as urea / formalin resin fine particles and fine hollow particles, and are included in waste paper and waste paper. The filler can also be reused. Two or more fillers can be used in combination.
In the present invention, the filler is generally added so that the paper (base paper) ash content is in the range of 3 to 20% by mass.

  In addition to pulp and filler, the base paper contains internal additives for papermaking, such as internal sizing agents, anionic, nonionic, cationic or amphoteric part retention improvers, drainage improvers, and paper strength enhancers. Auxiliaries can be added as needed. Specific examples of the internally added sizing agent include alkyl ketene dimer, alkenyl succinic anhydride, styrene-acrylic, higher fatty acid, petroleum resin sizing agent, rosin sizing agent and the like. Specific examples of part retention improvers, drainage improvers, and paper strength enhancers include, for example, polyvalent metal compounds such as aluminum (specifically, sulfate bands, aluminum chloride, sodium aluminate, basic Aluminum compounds, etc.), various starches, polyacrylamide, urea resin, polyamide / polyamine resin, polyethyleneimine, polyamine, polyvinyl alcohol, polyethylene oxide and the like. Moreover, it is also possible to use a bulking agent and a softening agent having a function of inhibiting binding between pulp fibers within a range that does not hinder the desired effect of the present invention. Specific examples of bulking agents and softening agents include, for example, polyhydric alcohol and fatty acid ester compounds, polyhydric alcohol and fatty acid ester compound polyoxyalkylene compounds, fatty acid polyamidoamines, polyhydric alcohol surfactants, An ionic surfactant etc. can be illustrated. Generally the addition amount of this bulking agent and a softening agent is about 0.05-2.0 mass% with respect to a pulp.

There are no particular limitations on the paper making conditions of the base paper, and for example, commercial scale paper machines such as long net paper machines, gap former paper machines, round net paper machines, short net paper machines, etc. It can be appropriately selected and used. The papermaking method may be any method such as acidic papermaking, neutral papermaking, or weak alkali papermaking. However, in recent years, since paper preservation is required, base paper made by neutral papermaking is preferred. The base paper can be subjected to normal size press treatment or pigment size press treatment, and starch derivative, polyvinyl alcohol, polyacrylamide or the like is appropriately used as an adhesive for such size press treatment. The basis weight of the base paper made under these paper making conditions is preferably 30 to 70 g / m ² .

  In the production method of the present invention, the above-mentioned coating solution is applied by a film transfer method. As a film transfer type coating apparatus, a gate roll coater, a blade, or a rod metering size press coater can be used.

  The coated paper thus obtained is passed through various publicly known finishing devices such as a super calender, gloss calender, soft calender, etc., and finished with a product.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, the part and% in an example show a mass part and the mass%, respectively.

  The physical properties of kaolin used in Examples and Comparative Examples were measured by the methods described below, and the results are shown in Table 1.

(Measurement of average particle diameter of pigments by light scattering method)
Using a laser diffraction particle size distribution analyzer SALD-2000 manufactured by Shimadzu Corporation, the particle size distribution of the pigment was measured, and the average particle size (d50 ₁ ) corresponding to 50 cumulative mass% was measured. The pigment dispersion used for the measurement is a region in which a pigment slurry having a solid content concentration of 5% by mass prepared by adding 0.05% of a dispersant (sodium polyacrylate) to the pigment can be measured with the measuring device. Diluted to obtain.

(Measurement of average particle size of pigment by sedimentation method)
The particle size distribution of the pigment was measured using a Sedigraph 5100 manufactured by US Micromeritics, and the average particle size (d50 ₂ ) corresponding to 50 cumulative mass% was measured. The pigment dispersion used for the measurement was prepared by adding a pigment slurry having a solid content concentration of 5% by mass prepared by adding 0.05% of a dispersant (sodium polyacrylate) to a pigment, soda pyrophosphate (trade name: Nankaline). It was obtained by diluting with a 0.1% aqueous solution (S1, manufactured by Rin Chemical Co., Ltd.) so that the pigment solid content concentration was about 1%, and subjected to ultrasonic dispersion treatment (30 W, 45 kHz, 60 minutes).

  The coated papers for printing obtained in the examples and comparative examples described later were evaluated by the following methods, and the results are shown in Table 1. The following evaluation test was performed in an environment of 23 ° C. and a relative humidity of 50%.

(White paper gloss)
It measured using the 75 degree glossiness meter according to ISO 8254-1 (1999), and calculated | required the average value.

(Smoothness of coated paper)
JAPAN TAPPI Paper Pulp Test Method No. The Oken type smoothness was measured according to 5-2 (2000).

(Printability (ink fillability and print smoothness))
In an RI printing machine (Meiji Seisakusho), printing was performed using 0.1 cc of printing ink (Values-G type, manufactured by Dainippon Ink & Chemicals, Inc.), and the transferred ink density (ink fillability), and The transfer uniformity (printing smoothness) of the ink was visually observed and comprehensively evaluated.
A: Printability is particularly excellent.
○: Printability is excellent.
Δ: Printability is slightly inferior.
X: Printability is inferior.

(Surface printing strength)
With a RI printing machine (Meiji Seisakusho), 0.4 cc of printing ink (paper test SD50 red BT = 13 made by T & K TOKA) is spread on the roll, and the ink is applied to the coated paper to be evaluated at a slow transfer speed. After printing and printing, knead the ink again without wiping the ink on the roll, overprint on the coated paper once printed, then knead the ink again without wiping the ink again on the roll. Overprinted on the printed coated paper and overprinted 3 times for convenience. Thereafter, the ink remaining on the roll was transferred to another paper, and the color loss of the transferred ink was visually evaluated.
A: No color loss.
○: Slightly missing color is observed.
Δ: Color loss is observed.
X: The color is remarkably lost.

Example 1
(Preparation of coating solution for coating layer)
Sodium polyacrylate as a dispersant, the aqueous solution was added 0.1 parts of the dispersion to kaolin, the average particle size d50 ₁ is 2.49μm as determined by light scattering method, average particle diameter measured by sedimentation method d50 ₂ Is 0.33 μm, d50 ₁ / d50 ₂ is 7.55, and the mass distribution of particles of 2 μm or less in the particle size distribution measurement curve by the precipitation method is 95.9%, and the mass distribution of particles of 0.3 μm or less is 45. 100 parts of 1% delaminated kaolin (trade name: Conzer Extreme, manufactured by Imeris Co., Ltd.) was dispersed with a Coreless disperser to prepare a pigment slurry. In this slurry, 10 parts of oxidized starch (trade name: Ace C, manufactured by Oji Cornstarch Co., Ltd.) as an adhesive with respect to 100 parts of pigment, styrene-butadiene copolymer latex (trade name: SMARTEX PA2323) , Particle diameter: 89 nm, manufactured by Nippon A & L Co., Ltd.) 10 parts (in terms of solid content) were sequentially added to finally prepare a coating solution having a solid content concentration of 53%.

(Create coated paper for printing)
Using a rod metering size press coater on a high-quality base paper (44 tsubo / m ² ) having a tenacity of 0.62 g / cm ³ , the dry coating amount per side of the coating liquid obtained above is 7 g / m. ^It was applied to both sides so as to be ^2, and dried. The coated paper thus obtained was passed through a super calender under the conditions of a roll temperature of 70 ° C. and a linear pressure of 200 kN / m to obtain a coated paper for printing.

Example 2
In the preparation of the coating liquid of Example 1, the compounding amount of oxidized starch was reduced to 2 parts in terms of solid content, the compounding amount of styrene-butadiene copolymer latex was increased to 12 parts in terms of solid content, and a water retention agent ( A coated paper for printing was obtained in the same manner as in Example 1, except that 0.03 part (trade name: S-350, manufactured by Somar) was added to prepare a coating solution.

Example 3
In the preparation of the coating liquid of Example 1, 85 parts of delaminated kaolin (trade name: Conzer Extreme) as a pigment component and heavy calcium carbonate having an average particle size of 0.8 μm (trade name: Hydrocurve 90, Bihoku powdered 15 parts of Kogyo Kogyo Co., Ltd., the amount of oxidized starch was increased to 15 parts in terms of solid content, and the latex was styrene-butadiene copolymer latex (trade name: SN-113I, particle size: 190 nm, Japan) A coated paper for printing was obtained in the same manner as in Example 1 except that the product was changed to A & L.

Example 4
In the preparation of the coating liquid of Example 1, 40 parts of delaminated kaolin (trade name: Konzer Extreme) as a pigment component and light calcium carbonate having an average particle size of 0.45 μm (trade name: Brilliant S-15, Shiraishi Calcium Co., Ltd.) 60 parts), the amount of oxidized starch is increased to 15 parts in terms of solid content, the latex is changed to styrene-butadiene copolymer latex (trade name: SN-113I, particle size: 190 nm), and the final A coated paper for printing was obtained in the same manner as in Example 1 except that the solid content concentration of the typical coating liquid was adjusted to 55%.

Comparative Example 1
In the preparation of the coating liquid of Example 1, as a pigment component, an average particle size d50 ₁ is 4.58μm as determined by light scattering method, average particle size d50 ₂ as measured by sedimentation method 0.46 _.mu.m, d50 1 / d50 ₂ Is kaolin (trade name: Konzer) in which the mass distribution of particles of 2 μm or less is 88.5% and the mass distribution of particles of 0.3 μm or less is 31.5% in the particle size distribution measurement curve by the sedimentation method. 1500 parts, manufactured by Imeris Co., Ltd.) and 15 parts heavy calcium carbonate having an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Flour Industry Co., Ltd.) In the same manner as in Example 1, except that the amount was increased to 15 parts in terms of conversion and the latex was changed to styrene-butadiene copolymer latex (trade name: SN-113I, particle size: 190 nm). To obtain a printing coated paper for.

Comparative Example 2
In the preparation of the coating liquid of Example 1, as a pigment component, an average particle size d50 ₁ is 1.95μm as determined by light scattering method, average particle size d50 ₂ as measured by sedimentation method 0.28 _.mu.m, d50 1 / d50 ₂ Is kaolin (trade name: Milagros), the mass distribution of particles of 2 μm or less in the particle size distribution measurement curve by sedimentation method is 94.9%, and the mass distribution of particles of 0.3 μm or less is 52.6%. J, manufactured by Engelhard Co., Ltd., and the latex was changed to styrene-butadiene copolymer latex (trade name: SN-113I, particle size: 190 nm). A paper was obtained.

Comparative Example 3
In the preparation of the coating solution of Comparative Example 2, as the pigment component, an average particle size d50 ₁ is 3.23μm as determined by light scattering method, average particle size d50 ₂ as measured by sedimentation method 0.65 _.mu.m, d50 1 / d50 ₂ Is 4.97, and a delaminated kaolin having a mass distribution of particles of 2 μm or less in a particle size distribution measurement curve by a sedimentation method is 81.2% and a mass distribution of particles of 0.3 μm or less is 26.2% (product) A coated paper for printing was obtained in the same manner as in Comparative Example 2 except that Name: Astra Plate (manufactured by Imeris) was used.

Comparative Example 4
In the preparation of the coating solution of Comparative Example 2, as the pigment component, an average particle size d50 ₁ is 1.41μm as determined by light scattering method, average particle size d50 ₂ as measured by sedimentation method 0.48 _.mu.m, d50 1 / d50 ₂ Is 2.94, and kaolin having a mass distribution of particles of 2 μm or less in a particle size distribution measurement curve by a sedimentation method is 96.5% and a mass distribution of particles of 0.3 μm or less is 29.2% (trade name: Para. A coated paper for printing was obtained in the same manner as in Comparative Example 2 except that printing (manufactured by PPSA) was used.

Comparative Example 5
In the preparation of the coating solution of Comparative Example 2, as the pigment component, an average particle size d50 ₁ is 3.71μm as determined by light scattering method, average particle size d50 ₂ as measured by sedimentation method 0.95 _.mu.m, d50 1 / d50 ₂ Is 3.91, a delaminated kaolin having a mass distribution of particles of 2 μm or less in a particle size distribution measurement curve by a sedimentation method is 75.0%, and a mass distribution of particles of 0.3 μm or less is 15.8% (product) A coated paper for printing was obtained in the same manner as in Comparative Example 2 except that Name: Capim NP (manufactured by Imeris Corporation) was used.

The coated paper obtained by coating the base paper with a coating solution containing 20% by mass or more of the specific delaminated kaolin pigment component by the film transfer method has excellent white paper gloss and surface smoothness. Moreover, it is excellent in printing suitability such as ink fillability, printing smoothness, and surface printing strength, and can be applied as a light-weight coated paper coated with a light-weight coating.

Claims (7)

In coated paper for printing having a coating layer mainly composed of pigment and an adhesive on at least one surface of the base paper, the coating layer is, as a pigment, an average particle size d50 ₁ as measured by light scattering method 2. in the range of 0～3.5Myuemu, the average particle diameter d50 ₂ as measured by sedimentation method is in the range of 0.20～0.55Myuemu, the average ratio of particle size d50 ₁ and an average particle diameter d50 ₂ of the (D50 ₁ / d50 ₂ ) is 4 or more, and in the particle size distribution measurement curve by the sedimentation method, the mass distribution of particles of 2 μm or less is 95% or more and the mass distribution of particles of 0.3 μm or less is 35 to 35 A coated paper for printing, comprising delaminated kaolin in a range of 50%, wherein a mass ratio of the delaminated kaolin in the pigment is 20 to 100% by mass. The coated paper for printing according to claim 1, wherein a mass ratio of the delaminated kaolin in the pigment is 30 to 100% by mass. The coated paper for printing according to claim 1 or 2, wherein the adhesive contains 2 to 25 parts by mass of a starch derivative with respect to 100 parts by mass of the pigment. 4. The adhesive according to any one of claims 1 to 3, further comprising 1 to 20 parts by mass of a copolymer latex having a particle size of 40 to 150 nm with respect to 100 parts by mass of the pigment. The coated paper for printing described. A method for producing a coated paper for printing in which a coating layer mainly composed of a pigment and an adhesive is provided on at least one side of a base paper, the method comprising the following steps A and B:
Step A: as coated liquid, the average particle size d50 ₁ as measured by light scattering method is in the range of 2.0～3.5Myuemu, average particle diameter d50 ₂ as measured by sedimentation method from 0.20 to 0. Particles within the range of 55 μm, the ratio of the average particle diameter d50 ₁ to the average particle diameter d50 ₂ (d50 ₁ / d50 ₂ ) is 4 or more, and in the particle size distribution measurement curve by the sedimentation method, particles of 2 μm or less The delaminated kaolin has a mass distribution of 95% or more and a mass distribution of particles of 0.3 μm or less in the range of 35 to 50%, and the mass ratio of the delaminated kaolin in the pigment is 20 A step of preparing a dispersion liquid of ˜100% by mass, and a step B: a step of applying the coating liquid prepared in the step A to at least one surface of a base paper by a film transfer method. Coated paper for printing manufacturing method characterized by Mukoto. 6. The method for producing a coated paper for printing according to claim 5, wherein 2 to 25 parts by mass of a starch derivative is added as an adhesive to 100 parts by mass of the pigment in the coating liquid. The method for producing a coated paper for printing according to claim 5 or 6, wherein a thickener or a water retention agent is added to the coating liquid.