Coated paper for printing

Abstract

Coated printing paper with a white paper gloss (75°) of more than 40% and less than 60%, with a coating weight of 5 to 15 g / m on at least one side of the base paper. 2 The outermost pigment coating layer contains amorphous calcium carbonate having an average particle size (D50) of 0.80 μm or less.

Description

[Technical field]

[0001] The present invention relates to a coated printing paper equivalent to A3 grade, and more particularly to a coated printing paper equivalent to A3 grade that has good printing surface texture and printing surface strength. [Background technology]

[0002] Coated printing papers are classified into grades A1 to A3 depending on the amount of coating. Generally, coated printing papers classified into grade A3 use 100% bleached chemical pulp as the base paper and have a coating amount of 5 to 15 g / m on one side. 2 Since it has a low coating weight, it has a good printed surface feel and is lightweight, and is used for applications such as catalogs, pamphlets, flyers, and posters that require aesthetic appeal. However, since the coating weight is low compared to A2 grade coated printing paper, which has a higher coating weight, it is difficult to achieve A2 grade level printed surface feel. Regarding improving the surface feel of coated printing paper, Patent Document 1 discloses the use of titanium dioxide as a pigment. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-163020 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for achieving good printed surface texture using calcium carbonate, which is commonly used in this field, instead of using titanium dioxide, which is used in Patent Document 1. Furthermore, the inventors conducted a preliminary study and found that attempts to improve printed surface texture tend to result in a decrease in printed surface strength. In view of this situation, an object of the present invention is to provide a coated printing paper equivalent to A3 grade that has good printed surface texture and printed surface strength. [Means for solving the problem]

[0005] The inventors have found that the above-mentioned problems can be solved by a coated printing paper having a pigment coating layer containing irregular fine calcium carbonate having a specific particle size. That is, the above-mentioned problems are solved by the following present invention. (1) A coated printing paper having a white paper gloss (75°) of more than 40% and less than 60%, Coating weight of 5-15g / m on at least one side of base paper 2 A pigment coating layer of A coated printing paper, the outermost pigment coating layer of which contains amorphous calcium carbonate having an average particle size (D50) of 0.80 μm or less. (2) Coated printing paper according to (1), in which the average particle size (D50) of the amorphous calcium carbonate is 0.50 μm or more. (3) The coated printing paper according to (1) or (2), wherein the outermost pigment coating layer contains 10 parts by weight or more of the amorphous calcium carbonate per 100 parts by weight of the pigment. (4) Coated printing paper according to any one of (1) to (3), wherein the average particle size (D50) of the amorphous calcium carbonate is 0.55 to 0.75 μm. (5) The coated printing paper according to any one of (1) to (4), wherein the outermost pigment coating layer contains 50 parts by weight or less of the amorphous calcium carbonate per 100 parts by weight of the pigment. (6) The coated printing paper according to any one of (1) to (5), wherein the outermost pigment coating layer contains 30 parts by weight or less of the amorphous calcium carbonate per 100 parts by weight of the pigment. Effect of the Invention

[0006] The present invention can provide coated printing paper equivalent to A3 grade that has good printing surface feel and printing surface strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present invention will be described in detail below. In the present invention, "-" includes its end points. That is, "X-Y" includes the values ​​of X and Y.

[0008] 1. Coated paper for printing Coated printing paper is paper for printing that has a pigment coating layer provided on a base paper. The pigment coating layer is a layer that contains a white pigment as a main component. The outermost pigment coating layer of the coated printing paper of the present invention contains amorphous calcium carbonate having an average particle size (D50) of 0.80 μm or less. The coated printing paper of the present invention can be subjected to commercial printing such as offset printing, gravure printing, and on-demand printing (laser method, inkjet method, electrophotographic method, etc.) on the paper surface. In addition, its applications include books, magazines, posters, envelopes, calendars, etc., but are not limited to these.

[0009] (1) Outermost pigment coating layer 1) Pigments The outermost pigment coating layer of the present invention contains amorphous calcium carbonate (hereinafter also referred to as "first calcium carbonate") having an average particle size (D50) of 0.80 μm or less. Irregular calcium carbonate is calcium carbonate that is not uniform in shape, and examples of such calcium carbonate include heavy calcium carbonate produced by physically crushing and classifying limestone, and light calcium carbonate produced in the causticizing step of the pulp manufacturing process (causticized light calcium carbonate, see Japanese Patent Publication No. 5274077).

[0010] When the pigment coating layer is present on both sides of the base paper, the outermost pigment coating layer on at least one side should contain the first calcium carbonate. Calcium carbonate has excellent binding properties with adhesives (binders) having acidic groups such as latex, which will be described later, and improves whiteness, so that good print surface strength, print surface texture, and whiteness can be achieved.

[0011] In the present invention, the average particle size (D50) is the volume 50% average particle size. In the present invention, the average particle size (D50) is measured by a laser diffraction method, and can be measured by a Mastersizer 3000 manufactured by Malvern, etc. The upper limit of the average particle size (D50) of the first calcium carbonate is preferably 0.75 μm or less, and more preferably 0.70 μm or less. From the viewpoint of the specific surface area of ​​the pigment and the binder requirement, the lower limit of the average particle size (D50) is preferably 0.50 μm or more, and more preferably 0.55 μm or more. When the average particle size (D50) is 0.80 μm or less, the coating layer becomes dense, so that glossiness is easily exhibited even with a low coating amount, and further, when a calendar treatment is performed, a high glossiness can be achieved. In addition, when the average particle size (D50) is less than 0.50 μm, the adhesive (binder) requirement increases, and the printing surface strength may decrease.

[0012] The lower limit of the amount of the first calcium carbonate in the outermost pigment coating layer is preferably 10 parts by weight or more, more preferably 20 parts by weight or more, based on 100 parts by weight of the pigment in the outermost pigment coating layer. The entire amount may be the first calcium carbonate, but when a first calcium carbonate with a small average particle size (D50) is used, the specific surface area of ​​the pigment increases and the amount of adhesive (binder) required increases, which tends to make it difficult to develop the print surface strength. On the other hand, when the content of the first calcium carbonate is increased, the development of print gloss and whiteness tend to improve. From the above viewpoints, the upper limit of the amount of the first calcium carbonate is preferably 80 parts by weight or less, more preferably 50 parts by weight or less, even more preferably 40 parts by weight or less, and most preferably 30 parts by weight or less. The first calcium carbonate is preferably heavy calcium carbonate or the above-mentioned causticized light calcium carbonate. When two or more types of first calcium carbonate with different D50 are used, the above-mentioned "amount of the first calcium carbonate" means the total amount of these. For example, when 70 parts by weight of the first calcium carbonate having a D50 of 0.8 μm and 30 parts by weight of the first calcium carbonate having a D50 of 0.5 μm are used, the "blended amount of the first calcium carbonate" is 100 parts by weight.

[0013] As the white pigment other than the first calcium carbonate, pigments that are commonly used in the field can be used. Examples of the pigment include inorganic pigments such as kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate salts, colloidal silica, and satin white, and organic pigments such as solid, hollow, and core-shell types. Although a combination of multiple types of these pigments may be used, it is preferable that the content of yellowish pigments such as kaolin and clay is small because there is a risk of reducing the whiteness.

[0014] As the white pigment other than the first calcium carbonate, it is preferable to use heavy calcium carbonate or light calcium carbonate (hereinafter also referred to as "second calcium carbonate") having an average particle size (D50) exceeding 0.80 μm. The shape of the second calcium carbonate is arbitrary, and may be irregular or uniform. In 100 parts by weight of the pigment in the outermost pigment coating layer, the total amount of the first and second calcium carbonates is preferably 90 parts by weight or more, more preferably 100 parts by weight (total amount). The second calcium carbonate is preferably heavy calcium carbonate or causticized light calcium carbonate. The amount of the first calcium carbonate in this embodiment is preferably as described above.

[0015] 2) Adhesive The outermost pigment coating layer of the present invention contains an adhesive (binder) as a matrix. The adhesive is not limited, and known adhesives can be used. Examples of such adhesives include latexes such as styrene-butadiene copolymers, styrene-acrylic copolymers, ethylene-vinyl acetate copolymers, butadiene-methyl methacrylate copolymers, vinyl acetate-butyl acrylate copolymers, maleic anhydride copolymers, and acrylic acid-methyl methacrylate copolymers; 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; starches such as oxidized starch, cationic starch, urea phosphate esterified starch, etherified starch such as hydroxyethyl etherified starch, and dextrin; and cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxymethyl cellulose. These can be used in combination.

[0016] From the viewpoint of printability and coatability, the amount of adhesive in the outermost pigment coating layer is preferably 5 to 30 parts by weight, more preferably 8 to 25 parts by weight, per 100 parts by weight of the pigment in the outermost pigment coating layer. If the amount of adhesive exceeds 30 parts by weight, the viscosity of the pigment coating liquid increases, and operational problems are likely to occur during coating. Furthermore, there is a tendency for the drying property of the ink to decrease during printing. On the other hand, if the amount of adhesive is less than 5 parts by weight, it becomes difficult to obtain sufficient print surface strength.

[0017] The coated printing paper of the present invention preferably contains 10 to 80% by weight of latex, more preferably 15 to 70% by weight of latex, of the total adhesive in the outermost pigment coating layer. Latex is an adhesive in the form of an emulsion. Styrene-butadiene copolymer latex is preferred as the latex. Compared with kaolin or clay, calcium carbonate has a good affinity with adhesives having acidic groups such as latex. Therefore, by using latex in the coated printing paper of the present invention, a coated printing paper having high printing surface strength, whiteness and printing surface texture can be obtained. It is also preferred to use starch as another adhesive.

[0018] 3) Other additives The outermost pigment coating layer of the present invention may contain, as necessary, various auxiliary agents that are typically blended in coated papers for printing, such as dispersants, thickeners, water retention agents, defoamers, water resistance agents, dyes, and coloring pigments.

[0019] (2) Other pigment coating layers When the coated printing paper of the present invention has two or more pigment coating layers, the amount of the first calcium carbonate in the pigment coating layers other than the outermost pigment coating layer (hereinafter also referred to as "other pigment coating layers") and the total amount of the first and second calcium carbonates are not limited, but are preferably within the ranges described above. The amount of adhesive in the other pigment coating layers and the content of latex and starches are not limited, but are preferably within the ranges described above. The other pigment coating layers may also contain the various auxiliaries described above.

[0020] (3) Coating amount Since the coated printing paper of the present invention is equivalent to A3 grade, the total coating amount of the outermost pigment coating layer and other pigment coating layers is 5 to 15 g / m2 in solid content per side. 2 and 9 to 15 g / m 2 The total coating weight of the outermost pigment coating layer and other pigment coating layers is preferably 5 g / m 2If the thickness is less than 100 mm, the unevenness of the base paper surface cannot be covered sufficiently, and sufficient white gloss may not be obtained. Furthermore, the receptivity of printing ink may be significantly reduced, and the printing quality required for A3 grade paper may not be obtained.

[0021] (4) Base paper 1) Pulp Known pulps can be used for the base paper, including chemical pulp, groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemothermomechanical pulp (CTMP), chemi-ground pulp (CGP), semi-chemical pulp (SCP), recycled paper pulp, and the like.

[0022] In the present invention, it is preferable to use chemical pulp. Chemical pulp includes those produced by the kraft pulp method and those produced by the sulfite pulp method, and both can be used in the present invention, but chemical pulp produced by the kraft method is preferable in terms of production costs. From the viewpoint of whiteness, etc., the content of chemical pulp in the raw material pulp is preferably 60% by weight or more of the total pulp, more preferably 80% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more.

[0023] 2) Filler Known fillers may be used in the base paper, including inorganic fillers such as heavy calcium carbonate, light calcium carbonate, clay, silica, light calcium carbonate-silica composite, kaolin, calcined kaolin, delaminated kaolin, white carbon, talc, magnesium carbonate, barium carbonate, barium sulfate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, titanium oxide, and amorphous silica produced by neutralizing sodium silicate with a mineral acid, and organic fillers such as urea-formaldehyde resin, melamine resin, polystyrene resin, and phenol resin.

[0024] In the present invention, among these, heavy calcium carbonate and light calcium carbonate, which are typical fillers in neutral papermaking and alkaline papermaking, are preferably used to improve opacity. Any calcium carbonate may be used as the filler, and may be the first calcium carbonate or the second calcium carbonate described above, but light calcium carbonate is preferred. The filler content in the base paper is not particularly limited, but is preferably 1 to 40% by weight, and more preferably 10 to 35% by weight. In consideration of the strength of the base paper, etc., it is more preferably 10 to 20% by weight.

[0025] 3) Other additives Known papermaking additives can also be used in the base paper. For example, aluminum sulfate and various anionic, cationic, nonionic or amphoteric retention improvers, drainage improvers, various paper strength enhancers, internal sizing agents, and other papermaking internal additives can be used as necessary. Examples of dry strength improvers include polyacrylamide and cationic starch, and examples of wet strength improvers include polyamide epichlorohydrin, polyamine epichlorohydrin, and polyamide polyamine epichlorohydrin. These chemicals are added to the extent that they do not affect the formation or runnability. Examples of internal sizing agents include alkyl ketene dimers, alkenyl succinic anhydrides, and rosin sizing agents. In addition, dyes, pigments, fluorescent whitening agents, pH adjusters, defoamers, pitch control agents, slime control agents, and other agents can also be added as necessary.

[0026] 4) Basis weight of base paper The basis weight of the base paper of the coated printing paper of the present invention is 20 to 200 g / m 2 It is preferable that the thickness is 20 to 150 g / m 2 More preferably, the thickness is 25 to 72 g / m 2 It is even more preferable that:

[0027] 5) Clear coating layer The coated printing paper of the present invention may have a clear (transparent) coating layer on one or both sides of the base paper described above. The clear coating layer refers to a coating layer obtained by applying a clear coating liquid (surface treatment liquid) containing starches such as starch, oxidized starch, various modified starches (self-modified, cation-modified, etc.), polyacrylamide, polyvinyl alcohol, and other water-soluble polymers as main components to the base paper using a coater (coating machine) such as a two-roll pond size press, a gate roll coater, a premetalling size press, a curtain coater, or a spray coater, and then drying the clear coating liquid. In the present invention, it is preferable to coat starches. In addition, the clear coating liquid may contain a sizing agent, etc.

[0028] By providing a clear coating layer on the base paper, the surface strength and smoothness of the base paper are improved, and the coating suitability when providing a pigment coating layer is also improved. The coating amount of the clear coating layer is 0.1 to 3.0 g / m2 in solid content per side. 2 It is preferable that the thickness is 0.2 to 2.0 g / m 2 More preferably, the thickness is 0.5 to 2.0 g / m 2 It is even more preferable that:

[0029] 2. Manufacturing method The coated printing paper of the present invention can be produced by known methods. (1) Manufacture of base paper The raw materials used for the base paper used in the present invention have already been described. The base paper is manufactured by a known papermaking method. For example, a Fourdrinier papermaking machine including a top wire, an on-top former, a gap former, a cylinder papermaking machine, a board papermaking machine using a combination of a Fourdrinier papermaking machine and a cylinder papermaking machine, a Yankee dryer machine, etc. may be used. The pH during papermaking may be acidic, neutral, or alkaline, but neutral or alkaline is preferred. The papermaking speed is not particularly limited. The base paper used in the present invention may be single-layered or multi-layered, but single-layered base paper is preferably used.

[0030] (2) Calendaring of the base paper Before coating the obtained base paper with a pigment coating liquid, it is preferable to subject the base paper to a calendering treatment using various calendering devices. As such a calendering device, a commonly used calendering device such as a super calender or a soft calender can be appropriately used. As for the calendering conditions, the temperature of the calender rolls, the linear pressure, the number of nips, the roll speed, the moisture content of the paper before calendering, etc. are appropriately selected according to the required quality. By subjecting the base paper to a calendering treatment, the smoothness of the base paper is improved, and the suitability for pigment coating is improved.

[0031] (3) Preparation of coating solution for pigment coating layer The coating liquid for the pigment coating layer can be prepared by dispersing or dissolving the pigment, adhesive, and other additives described above in water. The solid content and viscosity of the coating liquid for the pigment coating layer may be appropriately adjusted according to the coating method described below. As an example, in the case of a blade coater, the solid content is preferably 40 to 70% by weight, more preferably 60 to 70% by weight, and the viscosity is preferably in the range of 500 to 5000 mPa·s in terms of B-type viscosity measured at 60 rpm at room temperature. In addition, in the case of a roll coater, the solid content is preferably 30 to 60% by weight, more preferably 40 to 60% by weight. If the solid content is too low, backflow, etc., is likely to occur in the blade coater. In addition, if the solid content is too high, the load on the blade of the blade coater increases, leading to wear of the blade, and boiling occurs in the case of a roll coater, which tends to affect operability.

[0032] (4) Coating method The coating method is not limited, and known coating methods such as a roll coater and a blade coater can be used. The coating speed is also 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 one layer or two or more layers, but the coating method for the outermost pigment coating layer is preferably a blade coater, since this can improve the surface smoothness.

[0033] (5) Other processes The method for drying the wet pigment coating layer is not limited, and for example, a steam heating cylinder, a heated hot air dryer, a gas heater dryer, an electric heater dryer, an infrared heater dryer, etc. can be used.

[0034] As described above, the produced coated printing paper may be subjected to a calendering treatment. In order to obtain a high gloss, it is preferable to perform a calendering treatment on the coated printing paper. However, on the other hand, the pigment coating layer is compressed, the density increases, and the scattering coefficient increases, so that the whiteness tends to decrease. Therefore, as described later, the calendering conditions must be appropriately selected according to the required quality. When performing the calendering treatment, a commonly used calendering device such as a super calender or a soft calender can be appropriately used. As the calendering conditions, the temperature of the calender roll, the linear pressure, the number of nips, the roll speed, the moisture content of the paper before calendering, etc. are appropriately selected according to the required quality, but it is more preferable to perform a hot soft nip calendering treatment on the coated printing paper of the present invention. The calendering conditions are preferably a linear pressure of 140 to 300 kN / m, a temperature of 70 to 300°C, and the number of nips is 5 or more. The calendering speed is about 200 to 800 m / min.

[0035] 3. White paper properties (1)Basic weight The coating weight of the pigment coating layer has a greater effect on the printing quality of coated printing paper than the basis weight. Therefore, the basis weight of the coated printing paper of the present invention is not particularly limited as long as it is about the same basis weight as papers used in ordinary printing machines. However, from the viewpoint of transportability in a printing machine and stiffness of the paper, the basis weight of the coated printing paper of the present invention is preferably 30 to 250 g / m 2 and more preferably 50 to 220 g / m 2 It is.

[0036] (2) Paper gloss The white paper gloss is an index showing the degree of gloss of white paper, and in the present invention, it is the specular gloss at an angle of 75° to the normal to the paper surface, measured according to JIS-P8142. The coated printing paper of the present invention is a coated printing paper with high white paper gloss, which can be suitably used for catalogs and pamphlets with a luxurious feel. The white paper gloss of the coated printing paper of the present invention is more than 40% and less than 60%.

[0037] (3) Print surface texture and strength As described above, the coated printing paper of the present invention has excellent print surface texture and print surface strength because the outermost pigment coating layer contains amorphous calcium carbonate with an average particle size (D50) of 0.80 μm or less. Even if the average particle size (D50) is within the above range, if calcium carbonate with a uniform shape (such as columnar calcium carbonate) is used, the print surface texture can be improved, but on the other hand, the specific surface area of ​​the pigment becomes excessively high, requiring an excessive amount of adhesive (binder), resulting in a decrease in print surface strength. In this regard, the present invention uses amorphous calcium carbonate with a not excessively high specific surface area, so that the adhesive (binder) is not required in an excessive amount, preventing a decrease in print surface strength, and achieving both excellent print surface texture and excellent print surface strength. EXAMPLES

[0038] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. Parts by weight and % by weight are values ​​calculated on a solid content basis.

[0039] <Evaluation method> (1)Basic weight Measurements were performed based on JIS P 8124. (2) Paper thickness and density Measurements were taken based on JIS P 8118:2014. (3)ISO whiteness Based on JIS P 8148, measurements were taken using a color difference meter CMS-35SPX manufactured by Murakami Shikisai Co., Ltd. under conditions including ultraviolet light. (4) Paper gloss Measurements were performed based on JIS P 8142. (5) Opacity Measurements were performed based on JIS P 8149:2000.

[0040] (6) Print surface texture Using a Roland flatbed press (4 colors), printing was performed at a printing speed of 8000 sheets / hour using printing inks (NEX-NV M manufactured by Toyo Ink) in the order of black → blue → red → yellow, and the printed surface texture (unevenness in ink adhesion, uneven gloss, etc.) of the two-color (blue, red) printed area, the blue solid printed area, and the halftone (50%) printed area of ​​the resulting prints was visually evaluated. The evaluation criteria were as follows: A=Very good, B=Good, C=Slightly poor, D=Poor

[0041] (7)Print surface strength After printing with a RI-I type printing machine (Made by Mei Seisakusho) using printing ink (NEX-Y made by Toyo Ink), the print marks on the rubber roll were transferred to paper and the degree of picking was visually evaluated. The evaluation criteria were as follows: A = Not at all, B = Almost never, C = Slightly but does not affect use, D = Too much to use

[0042] [Example 1] Made of 100% chemical pulp by weight, containing 13.5% light calcium carbonate by weight as a filler. Basis weight: 45g / m 2 The base paper was prepared. 100 parts by weight of ultrafine heavy calcium carbonate (manufactured by Fimatec, product name: FMT100YF, D50 = 0.59 μm), the first calcium carbonate, was used as the pigment, and 5 parts by weight of styrene-butadiene copolymer latex and 6 parts by weight of oxidized starch were mixed as adhesives, and water was further added to obtain a coating liquid for the pigment coating layer with a solids concentration of 65% by weight.

[0043] On the base paper, the coating solution for the pigment coating layer is applied at a solid content of 10 g / m per side. 2 The coated paper was then double-coated with a blade coater so that the coating was as follows: the coated paper was then dried in a conventional manner, and calendered with a resin roll and a metal roll to obtain a coated printing paper. The coated printing paper was evaluated by the methods described above.

[0044] [Example 2] A coated printing paper was produced and evaluated in the same manner as in Example 1, except that 50 parts by weight of ultrafine heavy calcium carbonate (manufactured by Fimatec, product name: FMT100YF, D50 = 0.59 μm) as the first calcium carbonate and 50 parts by weight of fine heavy calcium carbonate (manufactured by Fimatec, product name: FMT97, D50 = 0.86 μm) as the second calcium carbonate were used as pigments.

[0045] [Example 3] A coated printing paper was produced and evaluated in the same manner as in Example 1, except that 20 parts by weight of ultrafine heavy calcium carbonate (manufactured by Fimatec, product name: FMT100YF, D50 = 0.59 μm) as the first calcium carbonate and 80 parts by weight of fine heavy calcium carbonate (manufactured by Fimatec, product name: FMT97, D50 = 0.86 μm) as the second calcium carbonate were used as pigments.

[0046] [Comparative Example 1] A coated printing paper was produced and evaluated in the same manner as in Example 1, except that 50 parts by weight of fine heavy calcium carbonate (manufactured by Fimatec, product name: FMT97, D50 = 0.86 μm), which is a second calcium carbonate, and 50 parts by weight of first-class kaolin (manufactured by Imerys Minerals Japan, product name: Premier, D50 = 2.67 μm) were used as the pigment. [Comparative Example 2] Coated printing paper was produced and evaluated in the same manner as in Example 1, except that calendering was not performed. [Comparative Example 3] 4.5g / m2 solids per side 2 A coated printing paper was produced and evaluated in the same manner as in Example 1, except that double-sided coating was performed using a blade coater so that the coating thickness was 100 μm.

[0047] [Example 4] A coated printing paper was produced and evaluated in the same manner as in Example 1, except that ultrafine causticized precipitated calcium carbonate (manufactured by Nippon Paper Industries Co., Ltd., D50=0.64 μm) was used as the first calcium carbonate.

[0048] [Examples 5 to 7] Except for changing the compounding ratio of the first calcium carbonate and the second calcium carbonate as shown in Table 1, coated printing papers were produced and evaluated in the same manner as in Example 1.

[0049] [Comparative Example 4] A coated printing paper was produced and evaluated in the same manner as in Example 4, except that a pulverized product (D50 = 0.37 μm) of columnar precipitated calcium carbonate (manufactured by Okutama Kogyo Co., Ltd., product name: TP123CS) was used instead of the ultrafine causticized precipitated calcium carbonate (manufactured by Nippon Paper Industries Co., Ltd., D50 = 0.64 μm).

[0050] [Comparative Example 5] Coated printing papers were produced and evaluated in the same manner as in Comparative Example 4, except that the amounts of styrene-butadiene copolymer latex and oxidized starch were changed as shown in Table 1.

[0051] [Table 1]

[0052] It is clear that the coated printing paper of the present invention has excellent printed surface texture and printed surface strength. In particular, it is clear that the coated printing papers of Examples 3, 5, 6, and 7 have extremely excellent printed surface texture and printed surface strength. On the other hand, the coated printing papers of the comparative examples do not have sufficient printed surface texture and printed surface strength. In particular, the coated printing paper of Comparative Example 4, which uses calcium carbonate with a uniform shape as the pigment in the outermost pigment coating layer, has low printed surface strength due to the large amount of adhesive (binder) required. In the coated printing paper of Comparative Example 5, in which the amount of adhesive (binder) was increased to compensate for this, the printed surface strength was improved but the printed surface texture was reduced.

Claims

1. A method for producing coated printing paper, comprising the steps of: The coated printing paper has a white paper gloss (75°) of more than 40% and less than 60%, Coating weight of 5 to 15 g / m on at least one side of the base paper ２ A pigment coating layer of the outermost pigment coating layer contains a first calcium carbonate which is an amorphous calcium carbonate having an average particle diameter (D50) of 0.75 μm or less, and a second calcium carbonate which is a heavy calcium carbonate or a light calcium carbonate having an average particle diameter (D50) of more than 0.80 μm, and the total amount of the first and second calcium carbonates is 90 parts by weight or more per 100 parts by weight of the pigment in the outermost pigment coating layer; The base paper does not contain amorphous silica and amorphous silicates, A coating step of providing a pigment coating layer having a coating weight of 5 to 15 g / m 2 on at least one side of the base paper, a coating step including providing an outermost pigment coating layer among the pigment coating layers using a pigment coating liquid containing the first calcium carbonate and the second calcium carbonate, Manufacturing method.

2. The method according to claim 1, wherein the first calcium carbonate has an average particle size (D50) of 0.50 μm or more.

3. A manufacturing method as described in claim 1 or 2, wherein in the coating process, an outermost pigment coating layer is provided containing 10 parts by weight or more of the first calcium carbonate per 100 parts by weight of pigment.

4. The method according to any one of claims 1 to 3, wherein the first calcium carbonate has an average particle size (D50) of 0.55 to 0.75 µm.

5. A manufacturing method described in any one of claims 1 to 4, wherein in the coating process, an outermost pigment coating layer is provided containing 50 parts by weight or less of the first calcium carbonate per 100 parts by weight of pigment.

6. A manufacturing method described in any one of claims 1 to 5, wherein in the coating process, an outermost pigment coating layer is provided containing 30 parts by weight or less of the first calcium carbonate per 100 parts by weight of pigment.

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