WO2017039015A1

WO2017039015A1 - Coated paper, coated base material, and method of evaluating property of ink drying

Info

Publication number: WO2017039015A1
Application number: PCT/JP2016/076044
Authority: WO
Inventors: 遼外岡; 周平稲田; 記之菱沼; 吉松　丈博; 詩織柿木; 篤小菅; 高橋　和哉
Original assignee: 日本製紙株式会社
Priority date: 2015-09-03
Filing date: 2016-09-05
Publication date: 2017-03-09

Abstract

This invention addresses the problems of providing a coated paper having an excellent property of paper alignment, providing a coated base material having an excellent property of ink drying, and providing a method of accurately evaluating the property of ink drying. The first problem is solved by a coated paper for printing that has a white-paper glossiness of less than 30% according to JIS-P8142, and a kinetic coefficient of friction greater than the static coefficient of friction, in terms of the static coefficient of friction and kinetic coefficient of friction measured according to ISO 15359. The second problem is solved by a coated base material having a sheet base material and a pigment coating layer provided thereon, the pore volume V of the pigment coating layer according to nitrogen adsorption being 0.04 cm³/g or greater. The third problem is solved by a method that includes a step of measuring the pore volume V or the average pore diameter m of the pigment coating layer by nitrogen adsorption.

Description

Coated paper, coated substrate, and ink drying property evaluation method

The present invention relates to a coated paper, a coated substrate, a production method thereof, and an ink drying property evaluation method. More specifically, the present invention relates to a coated paper for matte printing and a method for producing the same.

A coated substrate having a coating layer on a sheet-like substrate is used for various applications including printing. Of the coated substrates, coated papers in which the sheet-like substrate is paper (base paper) are particularly important in industry.

Coated paper is broadly divided into glossy coated paper and matte coated paper. Glossy coated paper includes art paper, super art paper, and coated paper used for catalogs, brochures, etc., which are conventionally used for high-grade printing, and these have a glossy finish with a high white paper gloss and printing gloss. It becomes. A matte coated paper is a coated paper having a lower white gloss or printing gloss than gloss coated paper, and includes dull coated paper and matte coated paper. In particular, the demand for matte coated paper has increased in recent years because the difference between blank gloss and printed gloss is larger than that of glossy coated paper, and the character portion after printing is easy to read. As a method of manufacturing matte coated paper, use of a pigment having a large particle diameter as a coating pigment, or a method of increasing the unevenness of the paper surface by not performing a calendar treatment after pigment coating. Is mentioned.

On the other hand, matte coated paper has larger surface irregularities than glossy coated paper, so the ink on the surface of the paper tends to sink. Therefore, it is necessary to transfer a large amount of ink in order to increase the printing density. Accordingly, the matte coated paper tends to have a low drying property because the amount of ink transferred increases. When the drying property of the ink is inferior, the problem of “setback” in which the ink is transferred to the other when the printed matter after printing is stacked is likely to occur. For this reason, in general, measures such as using a powder such as starch in order to prevent adhesion between the printed matter and paper, or taking a stand so as not to rub after overlapping are taken. In particular, when performing double-sided printing, if the above-mentioned “back-off” occurs, the printed image is soiled, and the value of the printed matter is significantly impaired. It is necessary to dry the ink until it no longer occurs. If the drying property of the ink is inferior, this standing time becomes longer, so that the working efficiency is lowered. Further, when printing on the opposite surface in double-sided printing, the printed image on the surface already printed by a roll or the like is rubbed, so that the printed image may be soiled if the drying property of the ink is inferior. Therefore, in order to cope with an improvement in printing speed and double-sided printing, there is a demand for the ability of ink to dry quickly.

In addition, for coated paper, the paper friction coefficient is adjusted in order to avoid problems such as the paper becoming slippery and becoming difficult to set on the printing press or difficult to cut. Has been studied. In general, it is known that the dynamic friction coefficient is smaller than the static friction coefficient in paper. For this reason, if the static friction coefficient is increased to some extent, a reasonably high dynamic friction coefficient can be obtained. Therefore, the prior art has mainly focused on adjusting the static friction coefficient. There is a technique that focuses on the relationship between the dynamic friction coefficient and the static friction coefficient (for example, Patent Document 1), but this technique also presupposes that the dynamic friction coefficient is smaller than the static friction coefficient.

As mentioned above, mat-coated paper is required to have ink quick drying, among other ink drying properties. However, due to recent printing circumstances, demand for ink quick drying is increasing in all coated papers. Specifically, the printing situation is increasing, especially in the field of sheet-fed printing, with the trend toward smaller lots and shorter delivery times, and H-UV printing (hybrid UV printing) has been adopted in printing machines. For example, there is a growing trend toward quick drying, such as the introduction of powderless ink.

The absorption of the solvent component in the ink into the coating layer is determined by the material of the coating layer, the coating layer structure, the printing conditions, the ink conditions, and the like. So far, in order to improve the drying properties of the ink, satin white is blended into the top coating layer, and by maintaining a certain void volume in the coating layer, the absorption and ink absorption properties and ink drying properties are improved. Various studies have been made, such as a method for improving (Patent Document 2) and a method using an ink having excellent drying properties and stain resistance (Patent Document 3). Many studies have focused on the coating layer structure.

Developing coated paper with excellent ink drying requires an accurate evaluation method for ink quick-drying. Regarding the relationship between the pigment coating layer and the solvent absorptivity, the Lucas-Washburn formula shown in formula (1), in which a large number of fine pores existing in the pigment coating layer are regarded as aggregates of capillaries, is widely used. ing. Here, L is the penetration depth of the solvent, r is the average radius of the capillary, t is time, γ is the surface tension of the solvent, θ is the contact angle between the capillary wall and the solvent, and η is the viscosity of the solvent. Assuming that the cylindrical structure of the pigment coating layer has n cylindrical ridges having an average radius r, the ink solvent permeation amount ν into the pigment coating layer is expressed by Formula (2). (1) can be transformed as shown in equation (3). d is the thickness of the pigment coating layer, V is the pore volume of the pigment coating layer, and k is the viscosity of the ink. That is, it is considered that the larger the pore diameter and pore volume in the pigment coating layer, and the smaller the pigment coating layer thickness, the greater the amount of solvent permeation per fixed time and the faster the ink quick drying.

As a method for quantitatively evaluating the pore structure of paper, the mercury intrusion method is generally widely used (Patent Document 4). However, since mercury is a toxic substance, careful handling is required. In recent years, due to consideration for human health and the environment, companies and organizations that restrict use have increased.

Japanese Patent Laid-Open No. 08-060597 Japanese Patent Laid-Open No. 11-247097 Japanese Patent Laying-Open No. 2015-063667 JP 2014-237898 A

In view of the above, the present invention provides a coated paper excellent in paper uniformity, a coated substrate having ink drying properties, particularly a coated paper for matte printing, and more accurately evaluates ink drying properties. It is an object to provide a method.

The above problems are solved by the present invention described below.
(1) Coating having a blank paper glossiness of less than 30% according to JIS-P8142, and having a dynamic friction coefficient larger than the static friction coefficient in the static friction coefficient and the dynamic friction coefficient measured according to ISO 15359 paper.
(2) A base paper, and a pigment coating layer containing a pigment and an adhesive provided thereon,
The pigment comprises kaolin or clay;
The coated paper according to (1), wherein the adhesive contains 20 to 50% by weight of latex in the total adhesive.
(3) The coated paper according to (1) or (2), which is a coated paper for printing.
(4) JAPAN TAPPI Paper Pulp Test Method No. 46. The coated paper according to (3), wherein the printing ink acceptability measured by 46 is 20 to 35.
(5) A step of blade coating a pigment coating liquid containing a pigment and an adhesive on a base paper,
The pigment comprises kaolin or clay;
The method for producing a coated paper according to any one of (1) to (4), wherein the adhesive contains 20 to 50% by weight of latex in the total adhesive.
(6) A coated base material comprising a sheet-like base material and a pigment coating layer provided thereon, wherein the pigment coating layer has a pore volume V of 0.04 cm ³ / g or more by a nitrogen adsorption method. .
(7) The coated substrate according to (6), wherein the average pore diameter m by the nitrogen adsorption method of the pigment coating layer is 30 nm or more.
(8) The coated substrate according to (6) or (7), wherein the pore volume V is 0.09 cm ³ / g or less.
(9) The coated substrate according to any one of (6) to (8), wherein the average pore diameter m is 60 nm or less.
(10) The outermost layer of the coated substrate is a pigment coated layer, and the static friction coefficient and the dynamic friction coefficient on the outermost pigment coated layer side measured according to ISO 15359 are static kinetic coefficients. The coated substrate according to any one of (6) to (9), which has a coefficient of friction greater than that.
(11) The coated substrate according to (10), wherein the outermost pigment coating layer contains 25 to 75% by weight of calcium carbonate in all pigments.
(12) The coated substrate according to (11), wherein the calcium carbonate is heavy calcium carbonate.
(13) The coated substrate according to (11), wherein the calcium carbonate is light calcium carbonate.
(14) The coated substrate according to any one of (10) to (13), wherein the outermost pigment coating layer contains 20 to 50% by weight of kaolin or clay in the total pigment.
(15) The coated substrate according to any one of (10) to (14), wherein the outermost pigment coating layer contains an adhesive and contains 20 to 80% by weight of latex in the adhesive.
(16) The total pore volume (cm ³ / m ² ) defined by the pore volume V (cm ³ / g) × the coating amount c (g / m ² ) of the pigment coating layer is 0.55. The coated base material according to any one of (6) to (15), which is ˜4.50 cm ³ / m ² .
(17) The coated substrate according to any one of (6) to (16), wherein the glossiness according to JIS-P8142 is less than 35%.
(18) JAPAN TAPPI Paper Pulp Test Method No. 46. The coated substrate according to any one of (6) to (17), which is a coated substrate for printing having a printing ink acceptability measured according to 46 of 20 to 35.
(19) The coated substrate according to any one of (6) to (18), which is coated paper.
(20) A step of measuring the pore volume V or the average pore diameter m of the pigment coated layer in the coated substrate comprising the sheet-shaped substrate and the pigment coated layer provided thereon by a nitrogen adsorption method , And a process for evaluating the ink drying property based on the relationship that the larger the V or m, the higher the ink drying property.
A method for evaluating ink drying properties.
(21) It further includes a step of measuring the coating amount c of the pigment coating layer,
The evaluation method according to (20), comprising a step of evaluating the ink drying property based on a relationship that the ink drying property increases as V / c or m / c increases.

According to the present invention, it is possible to provide a coated paper having excellent paper alignability, a coated substrate having ink drying properties, particularly a coated paper for matte printing, and a method for accurately evaluating ink drying properties.

Phase diagram of ink quick-drying and pore volume Phase diagram of ink quick-drying and average pore diameter

The present invention includes the following aspects.
-First coated paper: coated paper having a dynamic coefficient of friction higher than the static coefficient of friction-Second coated substrate: coated substrate comprising a pigment coated layer having a specific pore volume , Especially matte-coated paper for printing-Evaluation method of ink drying

Hereinafter, the present invention will be described in detail. In the present invention, “˜” includes the end value. That is, “X to Y” includes the values of X and Y. “X or Y” means either one of X or Y, or both.

I. First coated paper Coated paper Coated paper is paper having a coating layer such as a clear coating layer and a pigment coating layer on a base paper. The first coated paper of the present invention has a blank paper glossiness of less than 30% according to JIS-P8142, and a static friction coefficient and a dynamic friction coefficient measured according to ISO 15359 that are larger than the static friction coefficient. Has a coefficient of friction. This provides excellent paper alignment. The first coated paper of the present invention is preferably a coated paper for printing. Coated paper for printing is used after printing on the paper surface provided with a pigment coating layer by commercial printing, etc. by printing methods such as offset printing, gravure printing, on-demand printing (laser method, inkjet method, electrophotographic method, etc.) The paper that is used.

The application of the first coated paper is, for example, various printing papers such as flyer paper, book paper, library cover paper, and newspaper paper, various copy papers, various ink jet printing papers, thermal paper, pressure sensitive paper, craft paper, and pressure-sensitive recording. Paper, wrapping paper, paper container base paper, paperboard, thin paper, high quality paper, water-soluble paper, fancy paper, wallpaper, fiberboard, photographic paper, impregnating base paper, deodorant paper, incombustible paper, flame retardant paper, printed electronics paper , Tape paper, envelope paper, cosmetic paper, battery separator, ODP paper, various sanitary paper, tobacco paper, cup base paper, polishing paper, synthetic paper, and the like, but are not limited thereto. Among these, in one aspect, the first coated paper of the present invention is suitable as a printing paper used for various printing methods such as offset printing and gravure printing.

Hereinafter, the first coated paper (also referred to as “first coated paper for printing”) will be described using the coated paper for printing as an example.

(1) Blank paper glossiness Blank paper glossiness is an index indicating the degree of matte tone, and is measured according to JIS-P8142 in the present invention. The blank paper glossiness of the first printing coated paper of the present invention is preferably less than 35%, more preferably less than 30%. The lower limit of the white paper glossiness is not limited, but is preferably 15% or more.

(2) Printing ink acceptability Printing ink acceptability is an index indicating the ease of drying of the ink. In the present invention, the JAPAN TAPPI paper pulp test method No. It is measured according to 46. Specifically, printing ink acceptability is evaluated by the difference in whiteness before and after applying a certain amount of ink on paper, wiping the ink after a lapse of a certain time. Higher values mean better ink drying properties. In the first coated paper for printing of the present invention, the printing ink acceptability is preferably 20 or more, more preferably 21 or more, and further preferably 22 or more. The printing ink acceptability is preferably 35 or less, more preferably 31 or less, still more preferably 30 or less, and even more preferably 25 or less. On the other hand, if the printing ink acceptability exceeds 35, the drying property of the ink becomes excessive, and the printing glossiness decreases.

(3) Friction coefficient If the coated paper for printing slips too much in the printing machine, printing failure occurs. However, the inventors cannot solve this failure only by increasing the static friction coefficient. It was found that this tendency was particularly high in the coated paper for printing. The inventors have found that the problem in the static state and the problem in the dynamic state can be eliminated by applying a dynamic friction coefficient higher than the static friction coefficient to the coated paper for printing.

The first printing coated paper of the present invention has a dynamic coefficient of friction larger than the static coefficient of friction. The coefficient of friction is measured according to ISO 15359. ISO 15359 measures static friction coefficient and dynamic friction coefficient three times using the same sample, adopts the first and third values for static friction coefficient, and the third time for dynamic friction coefficient. The value of is adopted. In the present invention, the first value is adopted as the static friction coefficient. Although not limited, the increase rate calculated by [(dynamic friction coefficient) − (static friction coefficient)] / (static friction coefficient) is preferably 2 to 25%, and preferably 3 to 20%. It is more preferable. The specific friction coefficient is not limited, but the static friction coefficient is preferably 0.3 to 0.7, more preferably 0.4 to 0.6. When the friction coefficient is within this range, the above-mentioned problems before printing and problems in the printing press are eliminated.

(4) Pore volume V
The first printing coated paper of the present invention preferably has a pore volume V of 0.04 cm ³ / g or more. When the pore volume V is in this range, the ink drying property is excellent. The pore volume V is determined by a nitrogen adsorption method. The pore volume V is more preferably 0.045 cm ³ / g or more. Preferably the pore volume V is less than 0.09 cm ³ / g, more preferably 0.085cm ³ / g or less, and more preferably not more than 0.08 cm ³ / g. Specifically, in the present invention, the pore volume is determined from a desorption isotherm obtained by a nitrogen adsorption method. For measurement and analysis, Tristar 3000 manufactured by Shimadzu Corporation can be used. In the present application, the pore volume obtained by the Tristar 3000 is regarded as the pore volume of the pigment coating layer.

Since the pigment coating layer is formed on the base paper, the pore volume V of the pigment coating layer can be measured by peeling the base paper layer and the pigment coating layer. Alternatively, the pore volume of the laminate including the base paper layer and the pigment coating layer is measured, and the obtained pore volume value is converted into a value per unit coating amount from the weight ratio of the base paper and the pigment coating layer. Thus, the pore volume V of the pigment coating layer can be obtained. In the present invention, the latter method is preferred. Examples of the method for measuring the coating amount of the pigment coating layer include the method described in Japanese Patent No. 5827187.

(5) Total pore volume The total pore volume (cm ³ / m ² ) is defined by the pore volume V (cm ³ / g) × the coating amount c (g / m ² ). 55cm ³ / ^{m 2} or more, more preferably 0.60 cm ³ / ^{m 2} or more, more preferably 0.65 cm ³ / ^{m 2} or more. The upper limit of the total pore volume is preferably from 4.50cm ³ / ^{m 2} or less, more preferably 3.60cm ³ / ^{m 2} or less, more preferably 2.70cm ³ / ^{m 2} or less.

(6) Average pore diameter m
The average pore diameter m is determined by the method described above. From the viewpoint of ink drying properties, the average pore diameter m is preferably 30 nm or more. The upper limit of the average pore diameter m is preferably 60 nm or less. Specifically, in the present invention, the average pore diameter is determined from a desorption isotherm obtained by a nitrogen adsorption method. In the present application, the average pore diameter obtained by the Tristar 3000 is regarded as the average pore diameter of the pigment coating layer.

(7) Base Paper 1) Pulp Although known pulp such as chemical pulp, mechanical pulp, and waste paper pulp can be used as the base paper, it is preferable to use chemical pulp. The chemical pulp includes those produced by the kraft pulp method, those produced by the sulfite pulp method, bleached chemical pulp and unbleached chemical pulp, and in the present invention, these can be used. Is preferable from the viewpoints of production cost and quality. The content of the chemical pulp in the raw material pulp is 60% by weight or more in the total pulp, more preferably 80% by weight or more, further preferably 90% by weight or more, particularly 95% by weight or more from the viewpoint of whiteness and the like. preferable.
2) Filler A known filler may be used for the base paper. Known fillers include heavy calcium carbonate, light calcium carbonate, clay, silica, light calcium carbonate-silica composite, kaolin, calcined kaolin, deramikaolin, white carbon, talc, magnesium carbonate, barium carbonate, barium sulfate, water Inorganic fillers such as amorphous silica produced by neutralization of aluminum oxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, titanium oxide, sodium silicate, urea-formalin resin, melamine series Organic fillers such as resin, polystyrene resin and phenol resin are listed. Among these, heavy calcium carbonate and light calcium carbonate, which are typical fillers for neutral papermaking and alkaline papermaking, are preferably used to improve opacity. The filler content in the paper is not particularly limited, but is preferably 1 to 40% by weight, more preferably 10 to 35% by weight.
3) Others Known paper additives can also be used. For example, sulfuric acid bands and various anionic, cationic, nonionic or amphoteric yield improvers, drainage improvers, various paper strength enhancers and internal additive sizing agents, etc. Can be used. Examples of the dry paper strength improver include polyacrylamide and cationized starch, and examples of the wet paper strength improver include polyamidoamine epichlorohydrin. These chemicals are added within a range that does not affect the formation and operability. Examples of the internal sizing agent include alkyl ketene dimer, alkenyl succinic anhydride, and rosin sizing agent. Furthermore, dyes, colored pigments, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents, and the like can be added as necessary.
4) a first basis weight of base paper coated printing paper having a basis weight of the present invention of the base paper is preferably 40 ~ 160g / ^{m 2,} more preferably 45 ~ 150g / ^{m 2,} still is 50 ~ 130g / ^{m 2} Although preferable, it is not limited to these. The base paper of the present invention may be single-layer or multi-layer, but single-layer paper is preferred.

(8) Pigment coating layer 1) Pigment The pigment coating layer is a coating layer containing a pigment. The pigment coating layer may be a single layer or two or more layers.

In the present invention, known pigments can be used. Examples include kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, satin. Examples thereof include inorganic pigments such as white and organic pigments such as a solid type, a hollow type, and a core-shell type. You may use these pigments in combination of multiple types.
In order to achieve the physical properties, it is preferable to use calcium carbonate, kaolin, or clay. The total amount of the pigment is preferably 20 parts by weight or more and less than 50 parts by weight per 100 parts by weight of the pigment, more preferably 20 to 48 parts by weight, and even more preferably 30 to 47 parts by weight. As calcium carbonate, calcium carbonate such as heavy calcium carbonate and light calcium carbonate is preferable. As light calcium carbonate, you may use the light calcium carbonate (causticized light calcium carbonate) manufactured by the causticizing process of a pulp manufacturing process described in patent 5274077 gazette.

As the pigment, it is preferable to use a pigment having a particle size distribution of 80% or more when the particle size distribution is measured by a sedimentation method. The ratio is more preferably 85% or more, and further preferably 90% or more. The particle size distribution of the pigment by the sedimentation method can be measured by Sedigraph 5100 manufactured by Shimadzu Corporation.

2) Adhesive The pigment coating layer contains an adhesive (binder) as a matrix. The adhesive is not limited, and a known adhesive can be used. Various adhesives such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, maleic anhydride copolymer, acrylic acid / methyl Latex such as methacrylate copolymer; polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, and acetoacetyl-modified polyvinyl alcohol; proteins such as casein, soybean protein, and synthetic protein; oxidation Starch, positive starch, urea phosphated starch, etherified starch such as hydroxyethyl etherified starch, starch such as dextrin; carboxymethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, etc. Cellulose derivatives and the like. These multiple types can be used in combination.

The amount of the adhesive is preferably 5 to 20 parts by weight, more preferably 8 to 16 parts by weight with respect to 100 parts by weight of the pigment from the viewpoint of printability and coating suitability. When the total amount of the adhesive exceeds 20 parts by weight, the viscosity of the pigment coating liquid becomes high and operational troubles are likely to occur during coating. Furthermore, there is a tendency that the drying property of the ink is lowered. On the other hand, when the total amount of the adhesive is less than 5 parts by weight, it becomes difficult to obtain sufficient surface strength.

In order to achieve the above physical properties, it is preferable to contain 20 to 55% by weight of latex in all adhesives, and it is preferable to contain 25 to 45% by weight of latex. When two or more pigment coating layers are provided, the outermost pigment coating layer farthest from the base paper preferably contains 20 to 80% by weight of latex in the total adhesive, and 25 to 75% by weight. More preferably, it contains a latex, and more preferably contains 25-55% by weight latex. As other adhesives, it is particularly preferable to use starches, particularly oxidized starch. The reason why starches are preferable is that, compared to latex, starches have higher water retention of the pigment coating solution, so it is difficult for the coating solution to sink into the base paper, and the base paper is effectively coated with the pigment coating layer. can do. In other words, when starches are used, the coverage of the base paper by the pigment coating layer is improved. As a result, an improvement in printing quality, particularly printing glossiness, and an improvement in ink drying property can be expected.

3) Others The pigment coating layer contains various auxiliary agents blended with dispersants, thickeners, water retention agents, antifoaming agents, water resistance agents, and ordinary pigments for coated paper, as necessary. Also good.

2. Production Method The first coated paper for printing of the present invention can be produced by a known method, but it is preferably produced by blade coating a pigment coating solution containing a pigment and an adhesive on the base paper.

(1) Preparation of base paper The base paper has already been described. The base paper is manufactured by a known paper making method.

For example, using a long paper machine including top wire, on-top former, gap former, round paper machine, paperboard machine using a combination of long paper machine and round paper machine, Yankee dryer machine, etc. Can do. The pH during papermaking may be acidic, neutral or alkaline, but neutral or alkaline is preferred. The paper making speed is not particularly limited.

(2) Smoothing treatment of base paper Before applying the pigment coating liquid to the obtained base paper, it is preferable to smooth the base paper with various calendar devices. As such a calendar device, a commonly used calendar device such as a super calendar or a soft calendar can be used as appropriate. As the calendar finishing conditions, the temperature of the rigid roll, the calendar pressure, the number of nips, the roll speed, the paper moisture before the calendar, and the like are appropriately selected according to the required quality.

(3) Preparation of pigment coating liquid The pigment coating liquid can be prepared by dispersing or dissolving a pigment, an adhesive, and, if necessary, an additive in water. The composition of each component is adjusted so that the pigment coating layer can be formed. When performing blade coating, the solid content concentration of the pigment coating solution is preferably 40 to 70% by weight, more preferably 60 to 70% by weight. The viscosity of the pigment coating solution is preferably in the range of 500 to 3000 mPa · s as measured by the B-type viscosity measured at 60 rpm at room temperature.

(4) Coating method The coating method is not limited, and a known coating machine such as a roll coater or a blade coater can be used. The coating speed is not particularly limited, but is preferably 400 to 1800 m / min in the case of a blade coater and 400 to 2000 m / min in the case of a roll coater. In the present invention, the pigment coating layer may be applied with a single layer blade coater, may be applied with a roll coater and then applied with a blade coater, or may be applied with a blade coater and then applied with a blade coater. Although coating may be performed, it is preferable to use a blade coater for coating the outermost coating layer.

One or more pigment coating layers can be provided. Further, a clear coating layer may be provided on the base paper, and a pigment coating layer may be provided thereon.

The coating amount (g / m ² ) of the pigment coating layer in the present invention is preferably ² g / m ² or more, more preferably 5 g / m ² or more, and even more preferably 10 g / m ² or more in terms of solid content per side. If the coating amount is less than 5 g / m ² , the unevenness on the surface of the paper substrate cannot be sufficiently covered, and the acceptability of the printing ink may be significantly reduced. On the other hand, the coating amount of the pigment coating layer is preferably 50 g / ^{m 2} or less, more preferably ^{^{40g / m 2, 35g / m}} 2 or less is more preferred.

The first basis weight of coated printing paper of the present invention is not particularly limited, 50 g / ^{m 2} or more, a degree 260 g / ^{m 2} or less.

(5) Other steps The method for drying the wet coating layer is not limited. For example, a steam heating cylinder, a heated hot air air dryer, a gas heater dryer, an electric heater dryer, an infrared heater dryer, or the like can be used.

The first coated paper for printing of the present invention may be subjected to a smoothing treatment by various calendar devices after the wet coated layer is dried. As such a calendar device, a commonly used calendar device such as a super calendar or a soft calendar can be used as appropriate. As the calendar finishing conditions, the temperature of the rigid roll, the calendar pressure, the number of nips, the roll speed, the paper moisture before the calendar, and the like are appropriately selected according to the required quality.

II. 2nd coating base material A coating base material is a base material provided with a pigment coating layer on a sheet-like base material. The sheet-like substrate means a member having a large width and length with respect to the thickness, and examples thereof include paper, a polymer sheet, a metal foil, a nonwoven fabric, a plate, a cloth, a glass plate, a tile, and a fiber plate. . In the present invention, a film and a sheet are synonymous. In addition, as the application of the second coating substrate, specifically, for example, as paper, flyer paper, book paper, paperback cover paper, various printing papers such as newspaper paper, various copy papers, various inkjet printing papers, Thermal paper, pressure-sensitive paper, craft paper, pressure-sensitive recording paper, wrapping paper, paper container base paper, paperboard, thin paper, colored fine paper, water-soluble paper, fancy paper, wallpaper, photo paper, base paper for impregnation, deodorant paper, non-combustible paper, Examples include flame retardant paper, printed electronics paper, tape paper, envelope paper, decorative material paper, battery separator, ODP paper, various sanitary paper, tobacco paper, cup base paper, abrasive paper, and synthetic paper. Other applications include, but are not limited to, building materials, adsorbents, shield materials, and coating materials in various applications. In the present invention, it is preferable to use paper (base paper) as the base material, that is, the coated base material is coated paper. Among the coated papers, the coated paper for printing is preferable as described above, and the coated paper for matte printing is particularly preferable.

Hereinafter, in order to simplify the description, a second coated substrate (hereinafter also referred to as “second printed coated paper”) will be described by taking matte-tone coated coated paper as an example.

When a pigment with a large particle size is used as a coating pigment, the pore volume of the pigment coating layer decreases and the ink drying property decreases as the pigment particle size increases. It was difficult to achieve both. The second coated paper for printing of the present invention solves this problem.

1. Coated paper for printing The second coated paper for printing of the present invention comprises a base paper and a pigment coated layer provided thereon, and the pore volume V of the pigment coated layer by the nitrogen adsorption method is 0. 04 cm ³ / g or more. The printing coated paper has a blank paper glossiness of less than 35% according to JIS-P8142, and the TAPPI paper pulp test method of the printing coated paper No. The printing ink acceptability measured by 46 is preferably 20-35. The second coated paper for printing of the present invention is commercialized by printing methods such as offset printing, gravure printing, on-demand printing (laser method, ink jet method, electrophotographic method, etc.) on the surface of the paper provided with a pigment coating layer. Paper used for printing.

(1) Pore volume V
The pore volume V is determined by a nitrogen adsorption method. Since the second coated paper for printing of the present invention has a pore volume V of 0.04 cm ³ / g or more, the ink drying property is excellent. The pore volume V is more preferably 0.045 cm ³ / g or more. Preferably the pore volume V is less than 0.09 cm ³ / g, more preferably 0.085cm ³ / g or less, and more preferably not more than 0.08 cm ³ / g. Specifically, in the present invention, the pore volume is determined from a desorption isotherm obtained by a nitrogen adsorption method. For measurement and analysis, Tristar 3000 manufactured by Shimadzu Corporation can be used. In the present invention, the pore volume obtained by the Tristar 3000 is regarded as the pore volume of the pigment coating layer.

(2) Total pore volume The total pore volume (cm ³ / m ² ) is defined by the pore volume V (cm ³ / g) × the coating amount c (g / m ² ). 55cm ³ / ^{m 2} or more, more preferably 0.60 cm ³ / ^{m 2} or more, more preferably 0.65 cm ³ / ^{m 2} or more. The upper limit of the total pore volume is preferably from 4.50cm ³ / ^{m 2} or less, more preferably 3.60cm ³ / ^{m 2} or less, more preferably 2.70cm ³ / ^{m 2} or less.

(3) Average pore diameter m
The average pore diameter m is determined by a nitrogen adsorption method. From the viewpoint of ink drying properties, the average pore diameter m is preferably 30 nm or more. The upper limit of the average pore diameter m is preferably 60 nm or less. Specifically, in the present invention, the average pore diameter is determined from a desorption isotherm obtained by a nitrogen adsorption method. In the present invention, the average pore diameter obtained by the Tristar 3000 is regarded as the average pore diameter of the pigment coating layer.

(4) Glossiness of blank paper Blank glossiness is an index indicating the glossiness of blank paper and is measured according to JIS-P8142 in the present invention. Since the coated paper for printing of the present invention is a matte printed coated paper having a large difference between the blank paper gloss and the printed gloss as described above, the blank paper gloss is preferably less than 35%, more preferably less than 30%. . The lower limit of the white paper glossiness is not limited, but is preferably 15% or more.

(5) Printing ink acceptability Printing ink acceptability is measured as described for the first printing coated paper. In the second coated paper for printing of the present invention, the printing ink acceptability is 20 or more, preferably 21 or more, more preferably 22 or more. The printing ink acceptability is 35 or less, preferably 33 or less, more preferably 31 or less, and further preferably 30 or less. If the printing ink acceptability is less than 20, the drying property of the ink is not sufficient. On the other hand, if the printing ink acceptability exceeds 35, the drying property of the ink becomes excessive, and the printing glossiness decreases.

(6) Friction coefficient It is preferable that the 2nd printing coated paper of this invention has a dynamic friction coefficient larger than a static friction coefficient. The coated paper for printing may cause problems such as slipping of the paper, making it difficult to set the paper on the printing machine, or making cutting difficult. This is because this problem can be solved by having a large dynamic friction coefficient. Conventionally, in order to avoid the problem, it has been studied to adjust the friction coefficient of paper. In general, it is known that the dynamic friction coefficient is smaller than the static friction coefficient in paper. For this reason, if the static friction coefficient is increased to some extent, a reasonably high dynamic friction coefficient can be obtained. Therefore, the prior art has mainly focused on adjusting the static friction coefficient. Although there is a technique that focuses on the relationship between the dynamic friction coefficient and the static friction coefficient (for example, Japanese Patent Application Laid-Open No. 08-060597), this technique also presupposes that the dynamic friction coefficient is smaller than the static friction coefficient. . However, in the present invention, the above-mentioned problem can be solved by an idea different from the conventional idea.

The coefficient of friction is measured as described for the first printing coated paper. Although not limited, the increase rate calculated by [(dynamic friction coefficient) − (static friction coefficient)] / (static friction coefficient) is preferably 2 to 25%, and preferably 3 to 20%. It is more preferable. The specific friction coefficient is not limited, but the static friction coefficient is preferably 0.3 to 0.7, more preferably 0.4 to 0.6. When the friction coefficient is within this range, the above-mentioned problems before printing and problems in the printing press are eliminated.

(7) Base paper 1) Pulp The pulp is as described in the first coated paper for printing.
2) Filler The filler is as described in the first printing coated paper. Among these, when heavy calcium carbonate or light calcium carbonate, which is a typical filler in neutral papermaking or alkaline papermaking, is used, a high opacity improving effect can be obtained. As light calcium carbonate, you may use the light calcium carbonate (causticized light calcium carbonate) manufactured by the causticizing process of a pulp manufacturing process described in patent 5274077 gazette. The filler content in the paper is not particularly limited, but is preferably 1 to 40% by weight, more preferably 10 to 35% by weight.
3) Others In the present invention, known paper additives can also be used. The additive is as described in the first printing coated paper.
4) Basis weight of base paper The basis weight of the base paper is as described in the first coated paper for printing.

(8) Pigment coating layer 1) Pigment In the present invention, a known pigment can be used. Examples include kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, satin. Examples thereof include inorganic pigments such as white and organic pigments such as a solid type, a hollow type, and a core-shell type. You may use these pigments in combination of multiple types. Further, as the light calcium carbonate, causticized light calcium carbonate may be used.

In order to achieve the above-mentioned white paper glossiness, printing ink acceptability, friction coefficient, etc., in the present invention, it is preferable to use calcium carbonate, kaolin, or clay as a pigment. In particular, in order to achieve the friction coefficient, the outermost layer of the coated paper for printing is a pigment coating layer, and the outermost pigment coating layer contains 25 to 75% by weight of calcium carbonate in the total pigment. preferable. Although not limited as other pigments, kaolin or clay is preferably contained in an amount of 20 to 50% by weight in the total pigment of the outermost pigment coating layer. However, the total amount of calcium carbonate and kaolin or clay is adjusted so as not to exceed 100% by weight in the total pigment. The calcium carbonate is preferably heavy calcium carbonate or light calcium carbonate. More preferably, the light calcium carbonate is causticized light calcium carbonate.

In the present invention, the pore volume V and the average pore diameter m can be easily achieved by adjusting the average particle diameter of the pigment. Specifically, for example, the 50% volume average particle diameter (D50) of calcium carbonate is preferably 0.5 to 6.0 μm, and more preferably 0.5 to 2.0 μm. The 50% volume average particle diameter (D50) of kaolin or clay is preferably 1.0 to 6.0 μm, more preferably 2.0 μm to 5.5 μm. If the diameter is less than 1.0 μm, the glossiness of the white paper becomes high and it may be difficult to obtain a matte texture. Also, if the diameter is higher than 6.0 μm, operational troubles such as deterioration of the fluidity of the coating liquid and blade wear are likely to occur, and ink rubbing and drying properties deteriorate during printing. There is. The particle diameters of these pigments can be measured by a laser diffraction particle size distribution analyzer such as Mastersizer S manufactured by Malvern.

2) Adhesive The pigment coating layer contains an adhesive (binder) as a matrix. The adhesive used in the present invention is not limited, and a known adhesive can be used. Various adhesives such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, maleic anhydride copolymer, acrylic acid / Latex such as methyl methacrylate copolymer; polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, and acetoacetyl-modified polyvinyl alcohol; proteins such as casein, soy protein, and synthetic protein; Oxidized starch, positive starch, urea phosphated starch, etherified starch such as hydroxyethyl etherified starch, starches such as dextrin; carboxymethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, etc. Cellulose derivatives and the like. These multiple types can be used in combination. Preferably, a styrene / butadiene copolymer, oxidized starch, dextrin and the like can be mentioned.

In the present invention, as an adhesive for the outermost coating layer, various copolymers such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, It is preferable to use latex such as maleic anhydride copolymer and acrylic acid / methyl methacrylate copolymer, and it is more preferable to use styrene-butadiene copolymer. By adjusting the average particle diameter and glass transition temperature measured by the dynamic light scattering method of latex, it becomes easy to obtain high ink drying properties in coated paper for matte printing. The preferable average particle diameter of the latex is 70 to 150 nm, more preferably 70 to 120 nm. When the average particle size is small, the latex migrates during drying, and the formation of a uniform pigment coating layer may be hindered, resulting in uneven deposition. On the other hand, when the average particle size is large, the ink drying property is improved, but the ink sinks into the pigment coating layer, so that the printing gloss may be deteriorated. The preferable glass transition temperature of the latex is about −30 ° C. to 30 ° C., preferably −25 ° C. to 20 ° C., more preferably −20 ° C. to 15 ° C. When the glass transition temperature is too low, the coating operability may be deteriorated. On the other hand, when the glass transition temperature is too high, the surface strength of the coated paper is insufficient and the glossiness of the blank paper becomes excessive, making it difficult to obtain the matte blank paper glossiness required in the present invention.

In the present invention, in order to achieve the above physical properties, it is preferable to contain 20 to 80% by weight of latex in the total adhesive of the outermost pigment coating layer, and more preferably to contain 25 to 75% by weight of latex. More preferably, it contains 25 to 50% by weight of latex. As other adhesives, starches, particularly oxidized starch and dextrin are preferably used. The reason why starches are preferable is that, compared to latex, starches have higher water retention of the pigment coating solution, so it is difficult for the coating solution to sink into the base paper, and the base paper is effectively coated with the pigment coating layer. I think it can be done. In other words, when starches are used, the coverage of the base paper by the pigment coating layer is improved. As a result, an improvement in printing quality, particularly printing glossiness, and an improvement in ink drying property can be expected.

3. Production Method The second coated paper for printing of the present invention can be produced by a known method, but it is preferable to apply one or two layers of a pigment coating solution containing a pigment and an adhesive on the base paper. The construction method is preferably produced by a roll coater or a blade coater.
(1) Preparation of base paper Preparation of the base paper is as described in the first coated paper for printing.
(2) Base Paper Smoothing Process The base paper smoothing process is as described for the first coated paper for printing.
(3) Preparation of pigment coating solution The pigment coating solution of the present invention can be prepared by dispersing or dissolving a pigment, an adhesive, and, if necessary, an additive in water. The composition of each component is adjusted so that the pigment coating layer can be formed. When performing blade coating, the solid content concentration of the pigment coating solution is preferably 40 to 70% by weight, more preferably 60 to 70% by weight. The viscosity of the pigment coating solution is preferably in the range of 500 to 3000 mPa · s as measured by the B-type viscosity measured at 60 rpm at room temperature.
(4) Coating method The coating method is not limited, and a known coating machine such as a roll coater or a blade coater can be used. The coating speed is not particularly limited, but is preferably 400 to 1800 m / min in the case of a blade coater and 400 to 2000 m / min in the case of a roll coater. In the present invention, the pigment coating layer may be applied with a single layer blade coater, may be applied with a roll coater and then applied with a blade coater, or may be applied with a blade coater and then applied with a blade coater. Although coating may be performed, it is preferable to use a blade coater for coating the outermost pigment coating layer.

One or more pigment coating layers can be provided. Further, a clear coating layer may be provided on the base paper, and a pigment coating layer may be provided thereon. The outermost layer is preferably a pigment coating layer.

The coating amount c (g / m ² ) of the pigment coating layer in the present invention is preferably ² g / m ² or more, more preferably 5 g / m ² or more, more preferably 10 g / m ² or more in terms of solid content per side. . If the coating amount is less than 5 g / m ² , the unevenness on the surface of the paper substrate cannot be sufficiently covered, and the acceptability of the printing ink may be significantly reduced. On the other hand, the coating amount of the pigment coating layer is preferably 50 g / ^{m 2} or less, more preferably ^{^{40g / m 2, 35g / m}} 2 or less is more preferred.

Although the basic weight of the 2nd coated paper for printing of this invention is not specifically limited, It is about 50 g / m < ² > or more and 260 g / m < ² > or less.

(5) Other steps The method for drying the wet pigment coating layer is not limited, and for example, a steam heating cylinder, a heated hot air air dryer, a gas heater dryer, an electric heater dryer, an infrared heater dryer, or the like can be used.

The second coated paper for printing of the present invention may be subjected to a smoothing treatment with various calendar devices to such an extent that the matte texture is not impaired after the wet pigment coating layer is dried. As such a calendar device, a commonly used calendar device such as a super calendar or a soft calendar can be used as appropriate. As the calendar finishing conditions, the temperature of the rigid roll, the calendar pressure, the number of nips, the roll speed, the paper moisture before the calendar, and the like are appropriately selected according to the required quality.

III. Ink fast-drying evaluation method As a method for quantitatively evaluating the pore structure of paper, the mercury intrusion method is generally widely used, but the mesopore (2 to 50 nm) region, which is the void region of the pigment coating layer, is used. Then, since measurement is performed under high pressure conditions, the pores may be deformed. The evaluation method of the present invention can solve such problems.
(1) Measuring step of pore structure The method is a pore volume V or an average pore diameter of the pigment coating layer in a coating substrate comprising a sheet-like substrate and a pigment coating layer provided thereon. a step of measuring m by a nitrogen adsorption method. The nitrogen adsorption method is a method in which nitrogen molecules are adsorbed on the pigment coating layer and the pore volume or average pore diameter is obtained from the behavior of pressure and adsorption amount. Examples of the apparatus that can measure the pore structure by the nitrogen adsorption method include apparatuses such as Tristar 3000 manufactured by Shimadzu Corporation.
(2) Evaluation Step As represented by the above-described formula (3), the ink penetration rate, that is, the ink drying property increases as the pore volume V or the average pore diameter m of the pigment coating layer increases. Therefore, based on this relationship, the ink drying property can be evaluated when the same ink is used for the evaluation of the coated substrate having the pigment coating layer having a certain thickness.

As represented by Equation (3), the ink penetration rate is also affected by the coating amount of the pigment coating layer. Therefore, when the coating amount of the pigment coating layer is c, it is possible to evaluate in consideration of the coating amount c based on the relationship that the ink drying property increases as V / c or m / c increases. .

By the evaluation method of the present invention, the optimum pore volume V or average pore diameter m of the pigment coating layer for expressing ink drying properties can be obtained. The evaluation method of the present invention is suitable for evaluating coated paper whose base material is paper (base paper).

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Parts by weight and% by weight are values in terms of solid content.

1. First printing coated paper <Evaluation method>
(1) White paper glossiness Measured based on JIS-P8142.

(2) Printing ink acceptability JAPAN TAPPI Paper Pulp Test Method No. 46: Paper and paperboard-Printing ink acceptability test method-Measured based on K & N ink method. The whiteness was measured under the condition including UV light (UV-In).
(3) Static friction coefficient and dynamic friction coefficient It measured according to ISO15359. However, in the three repeated measurements, the first measured value was adopted as the static friction coefficient, and the third measured value was adopted as the dynamic friction coefficient.
(4) Ink drying by sensory evaluation Ink on the 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 inking density was black 2.00, the black solid printing part was touched with a fingertip every 10 minutes immediately after printing, and the degree of ink drying speed was sensory evaluated. If the evaluation is 4 or 3, there is no practical problem.
4: Very good 3: Good 2: Slightly inferior 1: Inferior (5) Ink rubbing Printing using offset sheet-fed ink (NEX-M manufactured by Toyo Ink) with an offset sheet-fed printing machine (four colors) manufactured by Roland. After printing at a speed of 8000 sheets / hr so that the solid ink density of the solid part is 1.80, the ink is conditioned for 24 hours according to JIS P8111. Was rubbed once with a load of 500 gf so as to fit the blank paper portion, and the ink transferred to the blank paper portion was visually evaluated as ink rub. If the evaluation is 4 or 3, there is no practical problem.
4: Extremely good 3: Good 2: Slightly inferior 1: Inferior (6) Halftone dot offset Offset sheet-fed printing machine (4 colors) manufactured by Roland (NEX-M manufactured by Toyo Ink Co., Ltd.) Were printed in the order of indigo red (CM) at a printing speed of 8000 sheets / hr so that the solid ink density was 1.60 indigo and 1.50 in red. The printed material obtained was visually evaluated for unevenness in the indigo color (CM) halftone (50%) printed part. If the evaluation is 4 or 3, there is no practical problem.
4: Extremely good 3: Good 2: Slightly inferior 1: Inferior (7) Print glossiness (difference in glossiness)
Using offset sheet-fed ink (NEX-M manufactured by Toyo Ink Co., Ltd.) with an offset sheet-fed printing machine (4 colors) manufactured by Roland, the ink thickness of the solid part is indigo at a printing speed of 8000 sheets / hr. .60 and Crimson (CM) were printed in order of Crimson 1.50. The glossiness of the indigo red (CM) solid printed part of the obtained printed matter was measured based on JIS P-8142.
The value obtained by subtracting the glossiness of the white paper from the printing glossiness is defined as the glossiness difference. If the glossiness difference is 20 or more, preferably 25 or more, the difference in glossiness between the printed portion and the blank paper portion is sufficiently obtained. No problem.
Gloss level difference (%) = Print gloss level (%)-Blank paper gloss level (%)
(8) Printing operability (paper alignment)
Using an offset sheet-fed printing machine (4 colors) manufactured by Roland, using offset sheet-fed ink (NEX-M manufactured by Toyo Ink Co., Ltd.), the ink density of the solid part is black at a printing speed of 8000 sheets / hr. After printing 500 copies so as to be 80, the paper alignment of the printed matter was visually evaluated. If the evaluation is 4 or 3, there is no practical problem.
4: Very good 3: Good 2: Slightly inferior 1: Inferior

[Example 1-1]
Heavy calcium carbonate slurry (product name: Carbital 97, ratio of particles having a particle diameter of 2 μm or less: 97%) as a pigment, 55 parts by weight (solid content) and secondary clay (product name: IMERYS) 45 parts by weight (solid content) of KCS, particles having a particle diameter of 2 μm or less: 85%, 4 parts by weight of styrene / butadiene copolymer latex as an adhesive, oxidized starch (manufactured by Nippon Corn Starch Co., Ltd.) , Trade name: SK200) was added in an amount of 6 parts by weight, and water was further added to obtain a pigment coating solution 1 having a solid concentration of 66% by weight.

As base paper, chemical pulp 100 wt%, and contained precipitated calcium carbonate 13% by weight as a filler, density of 0.73 g / cm ³ was prepared fine paper having a basis weight of 98 g / ^{m 2.} On the base paper, the pigment coating solution 1 was coated on both sides with a blade coater so that the dry coating amount per side was 15.0 g / m ^2, and then dried to obtain a coated paper for printing.

[Example 1-2]
Causticized light calcium carbonate slurry 1 (D50 = 1.02 μm) as a pigment 55 parts by weight (solid content) and secondary clay (manufactured by IMERYS, trade name: KCS, D50 = 4.9 μm) 45 parts by weight (solid content) 4 parts by weight of styrene / butadiene copolymer latex 1 (manufactured by A & L, product name: PB1537) and 6 parts by weight of oxidized starch (manufactured by Nippon Cornstarch, product name: SK200) are used as an adhesive. Further, water was added to obtain a pigment coating solution 1 ′ having a solid concentration of 66% by weight.

A coated paper for printing was obtained in the same manner as in Example 1-1 except that the pigment coating solution 1 'was used instead of the pigment coating solution 1.

[Comparative Example 1-1]
As a pigment, 100 parts by weight (solid content) of heavy calcium carbonate slurry (manufactured by IMERYS, trade name: Carbital 97, ratio of particles having a particle size of 2 μm or less: 97%) is used as an adhesive. 8 parts by weight of polymerized latex and 6 parts by weight of oxidized starch (manufactured by Nippon Corn Starch Co., Ltd., trade name: SK200) were blended, and water was further added to obtain a pigment coating solution 2 having a solid content concentration of 66% by weight. . A coated paper for printing was obtained in the same manner as in Example 1-1 except that the pigment coating solution 2 was used instead of the pigment coating solution 1.

[Comparative Example 1-2]
Heavy calcium carbonate slurry (product name: Carbital 97, ratio of particles having a particle diameter of 2 μm or less: 97%) as a pigment, 55 parts by weight (solid content) and secondary clay (product name: IMERYS) 45 parts by weight (solid content) of KCS, particles having a particle diameter of 2 μm or less: 85%, 7 parts by weight of styrene / butadiene copolymer latex as an adhesive, and oxidized starch (Nihon Corn Starch Co., Ltd.) Manufactured, trade name: SK200) was added in an amount of 3 parts by weight, and water was further added to obtain a pigment coating solution 3 having a solid concentration of 66% by weight. A coated paper for printing was obtained in the same manner as in Example 1-1 except that the pigment coating solution 3 was used in place of the pigment coating solution 1.

These results are shown in Table 1.

From Table 1, it is clear that the first coated paper for printing of the present invention is a coated paper for matte printing, has excellent ink quick-drying properties, and has a dynamic friction coefficient higher than the static friction coefficient. It is.

2. Second coated paper for printing <Evaluation method>
(1) Measurement of pore volume and average pore diameter The pore volume and average pore diameter of the coated paper were determined by a nitrogen adsorption method. For the measurement, Tristar 3000 manufactured by Shimadzu Corporation was used.
(Sample preparation)
A paper sample having a length of 40 cm and a width of 15 cm was divided into two layers so as to be uniform in the thickness direction, and a laminate including a pigment coating layer and a base paper layer was obtained. In the case of double-sided coated paper, two such laminates are obtained, and in the case of single-sided coated paper, one such laminate and one layer mainly composed of a base paper layer are obtained. A laminate including a pigment coating layer and a base paper layer was used as a sample sheet for measurement. In the case of double-sided coated paper, either one was used as a sample sheet for measurement. The basis weight t (g / m ² ) of the sample sheet was measured. Arbitrary four points in one sample sheet were selected, cut into strips, and then placed in a measurement cell so that the measurement sample had a dry weight of about 1 to 2 g. The absolutely dry weight at this time was set to w (g). Pretreatment was performed overnight in a vacuum state at a treatment temperature of 120 ° C.
(Measurement)
The pore volume and average pore diameter of the measurement sample were measured using the apparatus. Specifically, the pore volume and average pore diameter of the measurement sample were determined from the desorption isotherm using the BJH method, and the average value of four samples was taken, and the pore volume V ′ and average pore diameter of the measurement sample were taken. m ′. The pore volume V ′ was converted to a value per unit coating amount and used as the pore volume V of the pigment coating layer of the present invention. The obtained average pore diameter m ′ was directly used as the average pore diameter m of the pigment coating layer of the present invention. The pigment coating layer weight of the measurement sample is: pigment coating layer weight (g) = absolute dry weight w (g) of measurement sample × coating amount c (g / m ² ) ÷ basis weight t (g / g of sample sheet) It was calculated from m ^2). The coating amount c (g / m ² ) was determined by the measurement method described later.

Also by the mercury intrusion method, the pore volume and average pore diameter of the coated paper were determined in the same manner as the nitrogen adsorption method. For the measurement, Auto Pore 9500 manufactured by Shimadzu Corporation was used. Samples were prepared as in the nitrogen adsorption method. However, the amount of the measurement sample was about 0.13 g (absolute dry weight).
(Coating amount)
The coating amount was measured according to the method described in Japanese Patent No. 5827187. Specifically, it measured by the following procedures.
1) A measurement sample (paper) was cut into a size of 5 cm × 5 cm, and the weight x after humidity adjustment was measured at a temperature of 23 ° C. and a relative humidity of 50%.
2) The sample was placed so that the pigment coating layer was in contact with the styrene polymer plate, and was sandwiched with a watch glass and fixed with a clip.
3) Put into a dryer at 120 to 150 ° C., melt the styrene polymer, adhere to the pigment coating layer, allow to cool, adjust the humidity at about 23 ° C. and 50% relative humidity for about half a day, and measure the weight y. .
4) After the measurement sample obtained in the previous step was immersed in a copper ethylenediamine solution for about 3 to 4 hours, the base paper layer and the pigment coating layer were carefully peeled off using a brush. This process was repeated until there was no pulp fiber adhering to the pigment coating layer.
5) The pigment coating layer was washed with water and dried. After conditioning for about half a day at a temperature of 23 ° C. and a relative humidity of 50%, the weight z was measured.
6) The coating amount was calculated by the following formula.
Coating amount c (g / m ² ) = (x−A) × 400
A = yz

(2) Glossiness of blank paper Measurement was performed in the same manner as in Example 1-1.

(3) Printing ink acceptability Measured in the same manner as in Example 1-1.

(4) Static friction coefficient and dynamic friction coefficient The static friction coefficient and the dynamic friction coefficient were measured in the same manner as in Example 1-1.

(5) Ink drying property by sensory evaluation It was measured in the same manner as in Example 1-1.

(6) Halftone dot unevenness Measured in the same manner as in Example 1-1.

(7) Print glossiness (Glossiness difference)
Measurement was performed in the same manner as in Example 1-1.
(Base paper)
A high-quality paper having a density of 0.73 g / cm ³ and a basis weight of 98 g / m ² containing 100% by weight of chemical pulp as a base paper and 13% by weight of light calcium carbonate as a filler was prepared.

[Example 2-1]
Heavy calcium carbonate slurry 1 as a pigment (manufactured by PMMA Tech, trade name: FMT97, ratio of particles having a particle diameter of 2 μm or less by sedimentation method: 97%, D50 = 0.64 μm) 55 parts by weight (solid content) and 2 Grade clay (made by IMERYS, trade name: KCS, D50 = 4.9 μm) 45 parts by weight (solid content), and styrene / butadiene copolymer latex 2 (made by A & L, trade name: PB9501) as an adhesive 4 parts by weight of an average particle diameter of 80 nm and a glass transition temperature of -12 ° C. and 6 parts by weight of oxidized starch (manufactured by Nippon Cornstarch Co., Ltd., trade name: SK200), and further added water to a solid content concentration of 66% by weight A pigment coating solution 1 was obtained.

On the base paper, the pigment coating liquid 1 was coated on both sides with a blade coater so that the dry coating amount per side was 15.0 g / m ^2, and then dried to obtain a coated paper for printing.

[Example 2-2]
Heavy calcium carbonate slurry 1 as a pigment (manufactured by PMMA Tech, trade name: FMT97, ratio of particles having a particle diameter of 2 μm or less by sedimentation method: 97%, D50 = 0.64 μm) 55 parts by weight (solid content) and 2 Grade clay (made by IMERYS, trade name: KCS, D50 = 4.9 μm) 45 parts by weight (solid content), and styrene / butadiene copolymer latex 2 (made by A & L, trade name: PB9501) as an adhesive , 7 parts by weight of an average particle size of 80 nm, glass transition temperature of -12 ° C), 3 parts by weight of oxidized starch (trade name: SK200, manufactured by Nippon Corn Starch Co., Ltd.), water was added, and the solid content concentration was 66% by weight. A pigment coating solution 2 was obtained.

A coated paper for printing was obtained in the same manner as in Example 2-1, except that the pigment coating solution 2 was used instead of the pigment coating solution 1.

[Example 2-3]
Causticized light calcium carbonate slurry 1 (D50 = 1.02 μm) as a pigment 55 parts by weight (solid content) and secondary clay (manufactured by IMERYS, trade name: KCS, D50 = 4.9 μm) 45 parts by weight (solid content) 4 parts by weight of styrene / butadiene copolymer latex 1 (manufactured by A & L, trade name: PB1537, average particle diameter 110 nm, glass transition temperature 10 ° C.) as an adhesive, and starch oxide (manufactured by Nippon Corn Starch Co., Ltd., product) 6 parts by weight of SK200) was added, and water was further added to obtain a pigment coating solution 3 having a solid concentration of 66% by weight.

A coated paper for printing was obtained in the same manner as in Example 2-1, except that the pigment coating solution 3 was used instead of the pigment coating solution 1.

[Comparative Example 2-1]
As a pigment, 100 parts by weight (solid content) of heavy calcium carbonate slurry 1 (manufactured by PMMA Tech, trade name: FMT97, ratio of particles having a particle diameter of 2 μm or less by sedimentation method: 97%, D50 = 0.64 μm) Also, 8 parts by weight of styrene / butadiene copolymer latex 2 (A & L, trade name: PB9501, average particle size 80 nm, glass transition temperature-12 ° C.) as an adhesive, oxidized starch (made by Nippon Cornstarch, trade name) : SK200) was added in an amount of 6 parts by weight, and water was further added to obtain a pigment coating solution 4 having a solid content concentration of 66% by weight.

A coated paper for printing was obtained in the same manner as in Example 2-1, except that the pigment coating solution 4 was used instead of the pigment coating solution 1.

[Comparative Example 2-2]
Causticized light calcium carbonate slurry 1 (D50 = 1.02 μm) as a pigment, 95 parts by weight (solid content), fine clay (manufactured by IMERYS, trade name: Astra Glaze, D50 = 0.23 μm) 5 parts by weight (solid content) 5.8 parts by weight of styrene / butadiene copolymer latex 1 (trade name: PB1537, average particle diameter 110 nm, glass transition temperature 10 ° C.) as an adhesive, and oxidized starch (trade name, manufactured by Nippon Corn Starch Co., Ltd.) : SK200) was added in an amount of 5.3 parts by weight, and water was further added to obtain a pigment coating solution 5 having a solid content concentration of 66% by weight.

Next, 20 parts by weight (solid content) of causticized light calcium carbonate slurry 1 (D50 = 1.02 μm) and 80 parts by weight (solid content) of causticized light calcium carbonate slurry 2 (, D50 = 1.38 μm) were used as pigments. As an adhesive, 2.5 parts by weight of styrene / butadiene copolymer latex 1 (trade name: PB1537, average particle size 110 nm, glass transition temperature 10 ° C.), oxidized starch (manufactured by Nippon Cornstarch Co., Ltd., trade name: SK200) 21 parts by weight, and water was further added to obtain a pigment coating solution 6 having a solid content concentration of 66% by weight.

On the base paper, the pigment coating solution 6 was coated on both sides with a blade coater so that the dry coating amount per side was 4.5 g / m ^2, and then dried to obtain a lower layer coated paper. On the lower layer coated paper, the pigment coating solution 5 is coated on both sides with a blade coater so that the dry coating amount per side becomes 10.5 g / m ^2, and then dried to obtain a coated paper for printing. It was.

[Reference Example 2-1]
70 parts by weight of heavy calcium carbonate slurry 1 (manufactured by Pimatech, trade name: FMT97, D50 = 0.64 μm) as a pigment, 30 parts by weight of first grade clay (manufactured by IMERYS, trade name: Premier, D50 = 3.22 μm) (Solid content), 7 parts by weight of styrene / butadiene copolymer latex 2 (manufactured by A & L, trade name: PB9501, average particle diameter 80 nm, glass transition temperature −12 ° C.) as an adhesive, and oxidized starch ( 3 parts by weight of Nippon Cornstarch Co., Ltd., trade name: SK200) was blended, and water was further added to obtain a pigment coating solution 7 having a solid concentration of 66% by weight.

100 parts by weight (solid content) of heavy calcium carbonate slurry 1 (product name: FMT97, D50 = 0.64 μm) as a pigment and styrene / butadiene copolymer latex 1 (product) Name: 7 parts by weight of PB1537, average particle size 110 nm, glass transition temperature 10 ° C.) and 3 parts by weight of oxidized starch (product name: SK200, manufactured by Nippon Cornstarch Co., Ltd.). A weight% pigment coating solution 8 was obtained.

On the base paper, the pigment coating solution 8 was coated on both sides with a blade coater so that the dry coating amount per side was 8.5 g / m ² and then dried to obtain a lower layer coated paper. Obtained on the lower layer coating paper, double-sided coated so as to have a dry coating weight per one surface of the pigment coating solution 7 in the blade coater is 20.0 g / m ^2, then dried to coated printing paper It was.

[Reference Example 2-2]
Heavy calcium carbonate slurry 2 (manufactured by Phimatech, trade name: FMT90, ratio of particles having a particle diameter of 2 μm or less by precipitation method: 90%, D50 = 0.94 μm) as a pigment, 70 parts by weight, primary clay (IMERYS) Product name: Premier, D50 = 3.22 μm) 30 parts by weight (solid content), and styrene / butadiene copolymer latex 2 (manufactured by A & L, product name: PB9501, average particle diameter 80 nm) as an adhesive 7 parts by weight of a glass transition temperature of -12 ° C. and 3 parts by weight of oxidized starch (trade name: SK200, manufactured by Nippon Corn Starch Co., Ltd.). 9 was obtained.

A coated paper for printing was obtained in the same manner as in Reference Example 2-1, except that the pigment coating solution 9 was used in place of the pigment coating solution 7 as the coating solution.

[Example 2-4]
As a pigment, heavy calcium carbonate slurry 3 (manufactured by Phimatech, trade name: FMT75, proportion of particles having a particle size of 2 μm or less by sedimentation method: 75%, D50 average particle size 1.65 μm) 70 parts by weight, primary clay ( 30 parts by weight (solid content) manufactured by IMERYS, trade name: Premier, D50 = 3.22 μm, and styrene / butadiene copolymer latex 2 (manufactured by A & L, trade name: PB9501, average particle) as an adhesive 7 parts by weight of diameter 80nm, glass transition temperature -12 ° C), 3 parts by weight of oxidized starch (Nippon Cornstarch, trade name: SK200), water added, and pigment coating with a solid content concentration of 66% by weight A working liquid 10 was obtained.

A coated paper for printing was obtained in the same manner as in Reference Example 2-1, except that the pigment coating solution 10 was used in place of the pigment coating solution 7 as the coating solution.

[Example 2-5]
Causticized light calcium carbonate slurry 1 (D50 = 1.02 μm) as a pigment 55 parts by weight (solid content) and first grade clay (manufactured by IMERYS, trade name: KCS, D50 = 4.9 μm) 45 parts by weight (solid content) As an adhesive, 7.5 parts by weight of styrene / butadiene copolymer latex 1 (manufactured by A & L, trade name: PB1537, average particle diameter 110 nm, glass transition temperature 10 ° C.), oxidized starch (manufactured by Nippon Corn Starch Co., Ltd.) 2.7 parts by weight of trade name: SK200), and water was further added to obtain a pigment coating solution 11 having a solid content concentration of 66% by weight.

A coated paper for printing was obtained in the same manner as in Example 2-1, except that the pigment coating solution 11 was used instead of the pigment coating solution 1.

[Comparative Example 2-3]
A pigment coating liquid 12 was obtained in the same manner as in Example 2-5 using fine clay (trade name: Astra Glaze, D50 = 0.23 μm) instead of the primary clay. A coated paper for printing was obtained in the same manner as in Example 2-5, except that the pigment coating solution 12 was used instead of the pigment coating solution 11.

Table 2 shows the formulations and evaluation results of these examples, comparative examples, and reference examples.

As is apparent from Table 2, in the base paper and the printing coated paper having the pigment coating layer thereon, the pore volume V or the average pore diameter m of the pigment coating layer measured by the nitrogen adsorption method is large. The higher the ink drying property. In addition, the ink drying property increases as V / c or m / c increases when the coating amount of the pigment coating layer of the coated paper for printing is c.

Furthermore, the second printing coated paper of the present invention is a matte printing coated paper having a large difference between the blank paper glossiness and the printing glossiness. In Examples 2-1 to 2-5, It is apparent that a coated paper for matte printing having good ink drying properties and printing ink acceptance can be obtained by having a pore volume and an average pore diameter. In addition, the coated paper for matte printing of Examples 2-1 and 2-3 has a dynamic friction coefficient higher than the static friction coefficient, thereby suppressing paper slip and being excellent in paper alignment.

On the other hand, Comparative Examples 2-1 and 2-2 have low pore volume and average pore diameter, and accordingly, printing ink acceptability and ink drying properties are inferior. In addition, as shown in Reference Examples 2-1 and 2-2, if the glossiness of blank paper is higher than 35%, the pore volume, the average pore diameter can be reduced by reducing the particle diameter of the coating pigment. It is easy to obtain excellent printing ink acceptability and ink drying properties within the scope of the present application, but in the present invention, it is excellent in matte printing coated paper with reduced gloss. Ink acceptability and ink drying were achieved.

3. Evaluation of ink quick-drying [comparison between nitrogen adsorption method and mercury intrusion method]
With respect to the coated coated paper obtained in Reference Examples 2-1 and 2-2 and Example 2-4, the ink quick drying property was quantitatively evaluated by the following method.

<Quantitative evaluation of ink quick-drying>
Using an RI printing tester (RI-3 type, manufactured by Ishikawajima Sangyo Co., Ltd.), the standard tack ink for lithographic printing 0.8 cc was spread on a rubber roll, and the above was repeated three times so that the ink amount was uniform at a printing speed of 130 rpm. Printed on coated paper for printing. The ink printed on the coated paper is transferred to the paper every 2 minutes until 2 to 20 minutes after printing, and the Y value (brightness) of the ink transferred to the paper is measured by a portable spectral densitometer (manufactured by X-Rite, X-Rite 520). The Y value indicates the degree of ink transferred to paper without drying. The standard of ink quick-drying was set to Y = 80, and the time to achieve this was used as a quantitative indicator of drying.

Table 3 and FIGS. 1 and 2 show the results. As the pore volume and average pore diameter measured by the nitrogen adsorption method are increased, the ink quick drying property is improved. This tendency is in accordance with the relationship of the above-described formula (3). On the other hand, this correlation was not found in the mercury intrusion method. From the above, it is clear that the ink quick drying property can be measured more accurately by using the nitrogen adsorption method.

Claims

Coated paper having a blank paper glossiness of less than 30% according to JIS-P8142, and having a dynamic friction coefficient larger than the static friction coefficient in the static friction coefficient and the dynamic friction coefficient measured according to ISO 15359.
A base paper, and a pigment coating layer containing a pigment and an adhesive provided thereon,
The pigment comprises kaolin or clay;
The adhesive comprises 20-50 wt% latex in the total adhesive;
The coated paper according to claim 1.
The coated paper according to claim 1 or 2, which is a coated paper for printing.
JAPAN TAPPI Paper Pulp Test Method No. The coated paper according to claim 3, wherein the printing ink acceptability measured by 46 is 20 to 35.
On the base paper, equipped with a step of blade coating a pigment coating liquid containing pigment and adhesive,
The pigment comprises kaolin or clay;
The adhesive comprises 20-50 wt% latex in the total adhesive;
The method for producing a coated paper according to any one of claims 1 to 4.
A coated base material comprising a sheet-like base material and a pigment coating layer provided thereon, and having a pore volume V of 0.04 cm 3 / g or more by the nitrogen adsorption method of the pigment coating layer.
The coated substrate according to claim 6, wherein an average pore diameter m of the pigment coating layer by a nitrogen adsorption method is 30 nm or more.
The coated substrate according to claim 6 or 7, wherein the pore volume V is 0.09 cm 3 / g or less.
The coated substrate according to any one of claims 6 to 8, wherein the average pore diameter m is 60 nm or less.
The outermost layer of the coated substrate is a pigment coated layer, and the static friction coefficient and the dynamic friction coefficient on the outermost pigment coated layer side measured according to ISO 15359 are such that the dynamic friction coefficient is greater than the static friction coefficient. The coated substrate according to any one of claims 6 to 9, which is large.
The coated substrate according to claim 10, wherein the outermost pigment coating layer contains 25 to 75% by weight of calcium carbonate in all pigments.
The coated substrate according to claim 11, wherein the calcium carbonate is heavy calcium carbonate.
The coated substrate according to claim 11, wherein the calcium carbonate is light calcium carbonate.
The coated substrate according to any one of claims 10 to 13, wherein the outermost pigment coating layer contains 20 to 50% by weight of kaolin or clay in the total pigment.
The coated substrate according to any one of claims 10 to 14, wherein the outermost pigment coating layer contains an adhesive and contains 20 to 80% by weight of latex in the adhesive.
The total pore volume (cm 3 / m 2 ) defined by the pore volume V (cm 3 / g) × the coating amount c (g / m 2 ) of the pigment coating layer is 0.55 to 4. The coated substrate according to any one of claims 6 to 15, which is 50 cm 3 / m 2 .
The coated substrate according to any one of claims 6 to 16, which has a glossiness of less than 35% according to JIS-P8142.
JAPAN TAPPI Paper Pulp Test Method No. The coated substrate according to any one of claims 6 to 17, which is a coated substrate for printing having a printing ink acceptability measured according to 46 of 20 to 35.
The coated substrate according to any one of claims 6 to 18, which is coated paper.
A step of measuring the pore volume V or average pore diameter m of the pigment coated layer in a coated substrate comprising a sheet-shaped substrate and a pigment coated layer provided thereon by a nitrogen adsorption method; Or a process of evaluating the ink drying property based on the relationship that the larger m is, the higher the ink drying property is;
A method for evaluating ink drying properties.
Further comprising measuring a coating amount c of the pigment coating layer,
A step of evaluating the ink drying property based on the relationship that the larger the V / c or m / c, the higher the ink drying property;
The evaluation method according to claim 20, comprising: