Coated paper for printing

Abstract

To provide A3 grade coated paper for printing with good printability and print surface strength.SOLUTION: The coated paper for printing having a gloss level (75°) of more than 40% but less than 60% comprises a pigment coating layer provided on at least one side of base paper having a coating weight of 5 to 15 g / m2, and an outermost pigment coating layer contains amorphous calcium carbonate having an average particle size (D50) of 0.80 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Coated paper for printing is classified into grades such as A1 to A3 depending on the amount of coating. Generally, coated paper classified as A3 grade uses 100% bleached chemical pulp as the base paper and has a coating amount of 5 to 15 g / m² on one side. 2 Because of its light weight and good print surface texture, it is used for applications such as catalogs, brochures, flyers, and posters where aesthetic appeal is required. However, compared to A2 grade coated paper for printing, which has a higher coating amount, it has the challenge of not being able to achieve the same level of print surface texture as A2 grade paper. Regarding improving the surface texture of coated paper for printing, Patent Document 1 discloses the use of titanium dioxide as a pigment. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2014-163020 [Overview of the project] [Problems that the invention aims to solve]

[0004] There is a demand to achieve a good print surface feel using calcium carbonate, which is commonly used in this field, instead of titanium dioxide, which is used in Patent Document 1. Furthermore, the inventors have found through preliminary studies that attempts to improve the print surface feel tend to decrease the print surface strength. In view of these circumstances, the object of the present invention is to provide a coated paper for printing equivalent to A3 grade that has both a good print surface feel and print surface strength. [Means for solving the problem]

[0005] The inventors have found that a printed coated paper having a pigment coating layer containing amorphous fine calcium carbonate having a specific particle size solves the above problem. In other words, the above problem is solved by the present invention as described below. (1) Printing coated paper with a white gloss (75°) of more than 40% and less than 60%, At least one side of the base paper should have a single-sided coating of 5-15 g / m². 2 It comprises a pigment coating layer, Printing coated paper containing amorphous calcium carbonate in the outermost pigment coating layer having an average particle size (D50) of 0.80 μm or less. (2) The printing coated paper according to (1), wherein the average particle size (D50) of the amorphous calcium carbonate is 0.50 μm or more. (3) The printing coated paper according to (1) or (2), wherein 10 parts by weight or more of amorphous calcium carbonate are contained in 100 parts by weight of pigment in the outermost pigment coating layer. (4) A coated paper for printing 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) A printing coated paper according to any one of (1) to (4), wherein 100 parts by weight of pigment in the outermost pigment coating layer contains 50 parts by weight or less of amorphous calcium carbonate. (6) A printing coated paper according to any one of (1) to (5), wherein the outermost pigment coating layer contains 30 parts by weight or less of amorphous calcium carbonate in 100 parts by weight of pigment. [Effects of the Invention]

[0006] The present invention provides a coated paper for printing equivalent to A3 grade, which has good print surface texture and print surface strength. [Modes for carrying out the invention]

[0007] The present invention will now be described in detail. In this invention, "~" includes its endpoint. That is, "X~Y" includes the values ​​of X and Y.

[0008] 1. Coated paper for printing Printing coated paper is paper for printing that has a pigment coating layer provided on a base paper. The pigment coating layer is a layer mainly composed of white pigment. The outermost pigment coating layer of the printing coated paper of the present invention contains amorphous calcium carbonate having an average particle size (D50) of 0.80 μm or less. The printing coated 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, electrophotography method, etc.) on the paper surface. Its applications include, but are not limited to, books, magazines, posters, envelopes, calendars, etc.

[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. Amorphous calcium carbonate is calcium carbonate with a non-uniform shape, and examples include heavy calcium carbonate produced by physically crushing and classifying limestone, and light calcium carbonate produced in the causticization process of pulp manufacturing (caustic light calcium carbonate, see Japanese Patent No. 5274077).

[0010] If the pigment coating layer is present on both sides of the base paper, it is sufficient that the outermost pigment coating layer on at least one side contains the first calcium carbonate. Calcium carbonate exhibits excellent bonding properties with adhesives (binders) having acidic groups, such as latex, as described later, and also improves whiteness, thus enabling the achievement of good print surface strength, print surface feel, and whiteness.

[0011] In this invention, the average particle size (D50) is the 50% volume average particle size. In this invention, the average particle size (D50) is measured by laser diffraction and can be measured using a Malvern Mastersizer 3000 or the like. 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. If the average particle size (D50) is 0.80 μm or less, the coating layer becomes denser, making it easier to achieve gloss even with a low coating amount, and further high gloss can be achieved when calendering is performed. Also, if the average particle size (D50) is less than 0.50 μm, the adhesive (binder) requirement increases, which may reduce the strength of the printed surface.

[0012] The lower limit of the amount of first calcium carbonate blended in the outermost pigment coating layer is preferably 10 parts by weight or more, and more preferably 20 parts by weight or more, per 100 parts by weight of pigment in the outermost pigment coating layer. The entire amount may be first calcium carbonate, but if 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 achieve print surface strength. On the other hand, increasing the content of first calcium carbonate tends to improve the appearance of print gloss and whiteness. From the above viewpoint, the upper limit of the amount of first calcium carbonate blended 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 aforementioned caustic light calcium carbonate. When two or more types with different D50s are used as the first calcium carbonate, the "amount of first calcium carbonate blended" refers to the total amount of these. For example, if 70 parts by weight of a first calcium carbonate with a D50 of 0.8 μm and 30 parts by weight of a first calcium carbonate with a D50 of 0.5 μm are used, the "amount of first calcium carbonate blended" is 100 parts by weight.

[0013] As the white pigment other than the first calcium carbonate, pigments commonly used in the art can be used. Examples thereof include inorganic pigments such as kaolin, clay, engineered kaolin, delaminated clay, ground calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica and satin white, and organic pigments such as dense type, hollow type and core-shell type. A plurality of these pigments may be used in combination, but since there is a risk that whiteness may decrease, it is preferable that the content of yellowish pigments such as kaolin and clay is low.

[0014] As the white pigment other than the first calcium carbonate, it is preferable to use ground calcium carbonate or light calcium carbonate having an average particle diameter (D50) exceeding 0.80 µm (hereinafter also referred to as "second calcium carbonate"). The shape of the second calcium carbonate is arbitrary, and may be amorphous 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 carbonate is preferably 90 parts by weight or more, and more preferably 100 parts by weight (the total amount). The second calcium carbonate is preferably ground calcium carbonate or causticized light calcium carbonate. The blending 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 comprises an adhesive (binder) as a matrix. The adhesive is not limited, and known adhesives can be used. Examples thereof 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, soybean protein, and synthetic protein; starches such as oxidized starch, cationic starch, urea phosphate esterified starch, etherified starches such as hydroxyethyl etherified starch, and dextrin; and cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxymethyl cellulose. A plurality of these may be used in combination.

[0016] From the viewpoints of printability and coating suitability, the blending amount of the adhesive in the outermost pigment coating layer is preferably 5 to 30 parts by weight relative to 100 parts by weight of the pigment in the outermost pigment coating layer, and more preferably 8 to 25 parts by weight. When the blending amount of the adhesive exceeds 30 parts by weight, the viscosity of the pigment coating liquid increases, and operational troubles are likely to occur during coating. Furthermore, a tendency for the drying property of ink to decrease during printing is observed. On the other hand, when the blending amount of the adhesive is less than 5 parts by weight, it becomes difficult to obtain sufficient printing surface strength.

[0017] The coated paper for printing of the present invention preferably contains 10 to 80% by weight of latex in the total adhesive in the outermost pigment coating layer, and more preferably 15 to 70% by weight of latex. Latex is an adhesive in the form of an emulsion. Styrene-butadiene copolymer latex is preferred as the latex. Calcium carbonate has better affinity with adhesives having acidic groups such as latex compared to kaolin or clay. Therefore, by using latex in the coated paper for printing of the present invention, it is possible to obtain coated paper for printing with high print surface strength, whiteness, and print surface feel. It is also preferable to use starches as other adhesives in combination.

[0018] 3) Other additives The outermost pigment coating layer of the present invention may optionally contain various auxiliary agents commonly used in printed coated paper, such as dispersants, thickeners, water-retaining agents, defoaming agents, water-resistant agents, dyes, and coloring pigments.

[0019] (2) Other pigment coating layers When the printed coated 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 range described above. Furthermore, 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 range described above. In addition, the other pigment coating layers may contain the various auxiliary agents described above.

[0020] (3) Coating amount Since the printed coated paper of the present invention is equivalent to A3 grade, the total coating amount, including the outermost pigment coating layer and other pigment coating layers, is 5 to 15 g / m² in solid content per side. 2 It is 9-15 g / m 2 Preferably, the total coating weight of the outermost pigment coating layer and other pigment coating layers is 5 g / m². 2If the thickness is less than this, the surface irregularities of the base paper may not be sufficiently covered, resulting in insufficient white paper gloss. Furthermore, the receptivity of printing ink may be significantly reduced, potentially preventing the achievement of the print quality required for A3 grade paper.

[0021] (4) Base paper 1) Pulp Any known pulp can be used as the base paper. Examples of known pulps include chemical pulp, wood pulp (GP), refined wood pulp (RGP), thermomechanical pulp (TMP), chemothermetic pulp (CTMP), chemigland pulp (CGP), semi-chemical pulp (SCP), and recycled paper pulp.

[0022] In the present invention, it is preferable to use chemical pulp. Chemical pulp can be produced by the Kraft pulping method or the sulfite pulping method, and both can be used in the present invention, but chemical pulp produced by the Kraft method is preferable in terms of production cost. From the viewpoint of whiteness and other factors, the chemical pulp content in the raw material pulp is preferably 60% by weight or more, 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. Known fillers include inorganic fillers such as heavy calcium carbonate, light calcium carbonate, clay, silica, light calcium carbonate-silica composites, kaolin, calcined kaolin, delamikaolin, white carbon, talc, magnesium carbonate, barium carbonate, barium sulfate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, zinc oxide, titanium dioxide, and amorphous silica produced by neutralization of sodium silicate with mineral acids, as well as organic fillers such as urea-formaldehyde resin, melamine resin, polystyrene resin, and phenolic resin.

[0024] In this invention, among these, heavy calcium carbonate and light calcium carbonate, which are typical fillers in neutral papermaking and alkali papermaking, are preferably used to improve opacity. The calcium carbonate used as a filler is arbitrary and may be either the first calcium carbonate or the second calcium carbonate as described above, but light calcium carbonate is preferred. The filler ratio in the base paper is not particularly limited, but is preferably 1 to 40% by weight, and more preferably 10 to 35% by weight. Considering the strength of the base paper, 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, various anionic, cationic, nonionic, or amphoteric yield improvers, water drainage improvers, various paper strength enhancers, and internal sizing agents can be used as needed. Examples of dry paper strength improvers include polyacrylamide and cationized starch, while examples of wet paper strength improvers include polyamide epichlorohydrin, polyamine epichlorohydrin, and polyamide polyamine epichlorohydrin. These chemicals are added within a range that does not affect the form or operability. Examples of internal sizing agents include alkyl ketene dimers, alkenyl succinic anhydride, and rosin sizing agents. Furthermore, dyes, pigments, fluorescent whitening agents, pH adjusters, defoamers, pitch control agents, slime control agents, etc., can also be added as needed.

[0026] 4) Basis weight of the base paper The basis weight of the base paper for the coated printing paper of the present invention is 20-200 g / m². 2 Preferably, it is 20-150 g / m² 2 It is more preferable that the amount be 25-72 g / m². 2 It is even more preferable that this be the case.

[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 aforementioned base paper. The clear coating layer refers to a coating layer obtained by, for example, applying a clear coating liquid (surface treatment liquid) mainly composed of starches such as starch, oxidized starch, and various modified starches (self-modification, cationic modification, etc.), and water-soluble polymers such as polyacrylamide and polyvinyl alcohol onto base paper using a coater (coating machine) such as a 2-roll pond size press, gate roll coater, premetering size press, curtain coater, or spray coater, followed by drying. In the present invention, it is preferable to apply starches. Further, the clear coating liquid may contain a sizing agent or the like.

[0028] When a clear coating layer is provided on 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, expressed as solid content per side, is 0.1 to 3.0 g / m 2 , preferably 0.2 to 2.0 g / m 2 , more preferably 0.5 to 2.0 g / m 2 , and even more preferably within this range.

[0029] 2. Manufacturing Method The coated printing paper of the present invention can be manufactured by a known method. (1) Manufacture of Base Paper The raw materials used for the base paper employed in the present invention are as described above. The base paper is manufactured by a known papermaking method. For example, the manufacture can be carried out using a Fourdrinier paper machine including a top wire, an on-top former, a gap former, a cylinder paper machine, a paperboard machine combining a Fourdrinier paper machine and a cylinder paper machine, a Yankee dryer machine, or the like. The pH during papermaking may be acidic, neutral or alkaline, but neutral or alkaline is preferable. The papermaking speed is also not particularly limited. The base paper employed in the present invention may be a single layer or a multilayer, but a single-layer base paper is preferably used.

[0030] (2) Calendering Treatment of Base Paper Before applying the pigment coating solution to the obtained base paper, it is preferable to calender the base paper using various calendering devices. Commonly used calendering devices such as supercalenders and soft calenders can be used as appropriate. Calendering conditions, such as the calender roll temperature, linear pressure, nip count, roll speed, and paper moisture content before calendering, are appropriately selected according to the required quality. Calendering the base paper improves its smoothness and thus its suitability for pigment coating.

[0031] (3) Preparation of coating solution for pigment coating layer The coating solution for the pigment coating layer can be prepared by dispersing or dissolving the aforementioned pigment, adhesive, and other additives in water. The solid content concentration and viscosity of the coating solution for the pigment coating layer can be adjusted as appropriate according to the coating method described later. As an example, for a blade coater, the solid content concentration is preferably 40-70% by weight, more preferably 60-70% by weight, and the viscosity is preferably in the range of 500-5000 mPa·s for the B-type viscosity measured at 60 rpm at room temperature. For a roll coater, the solid content concentration is preferably 30-60% by weight, more preferably 40-60% by weight. If the solid content concentration is too low, backflow and other problems are likely to occur in a blade coater. If the solid content concentration is too high, the load on the blades will increase in a blade coater, leading to increased blade wear, and boiling may occur in a roll coater, thus affecting operability.

[0032] (4) Coating method The coating method is not limited, and known coating methods such as roll coaters and blade coaters can be used. The coating speed is also not particularly limited, but 400 to 1800 m / min is preferred for blade coaters, and 400 to 2000 m / min for roll coaters. 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 because it can improve the smoothness of the surface.

[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 mentioned above, the manufactured coated paper for printing may be calendered. Calendering the coated paper for printing is preferable to obtain high gloss, but on the other hand, the pigment coating layer is compressed, increasing its density and raising the scattering coefficient, which tends to decrease the whiteness. Therefore, as described later, the calendering conditions must be appropriately selected according to the required quality. When calendering is performed, commonly used calendering devices such as supercalenders and soft calenders can be used as appropriate. Calendering conditions such as the temperature of the calender roll, linear pressure, number of nips, roll speed, and moisture content of the paper before calendering are appropriately selected according to the required quality, but in the case of the coated paper for printing of the present invention, hot soft nip calendering is more preferable. The calendering conditions are preferably a linear pressure of 140 to 300 kN / m, a temperature of 70 to 300°C, and a number of nips of 5 or more. The calendering speed is about 200 to 800 m / min.

[0035] 3.White paper properties (1)Basic weight For coated paper used for printing, the amount of pigment coating layer has a greater influence on the print quality than the basis weight. Therefore, the basis weight of the coated paper used for printing according to the present invention is not particularly limited and can be anything other than the basis weight of paper used in a normal printing press. However, from the viewpoint of transportability in a printing press and paper rigidity, the basis weight of the coated paper used for printing according to the present invention is preferably 30 to 250 g / m². 2 More preferably 50-220 g / m² 2 That is the case.

[0036] (2) Glossiness of white paper White paper gloss is an index indicating the degree of gloss on white paper, and in this invention, it is measured according to JIS-P8142 as specular gloss at an angle of 75° to the normal of the paper surface. The coated paper for printing of this invention is suitable for use in high-quality catalogs and brochures, and therefore has high white paper gloss. The white paper gloss of the coated paper for printing of this invention is greater than 40% and less than 60%.

[0037] (3) Print surface feel and print surface strength As described above, the printing coated paper of the present invention contains amorphous calcium carbonate with an average particle size (D50) of 0.80 μm or less in the outermost pigment coating layer, thus possessing excellent print surface texture and print surface strength. Even if the average particle size (D50) is within the above range, using uniformly shaped calcium carbonate (such as columnar calcium carbonate) can improve the print surface texture, but on the other hand, the specific surface area of ​​the pigment becomes excessively high, resulting in an excessive requirement for adhesive (binder) and a decrease in print surface strength. In this respect, the present invention uses amorphous calcium carbonate with an excessively high specific surface area, so the requirement for adhesive (binder) does not become excessive, suppressing 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 specifically described below with reference to examples, but the present invention is not limited thereto. Parts by weight and weight percent are values ​​on a solid content basis.

[0039] <Evaluation Method> (1)Basic weight Measurements were taken in accordance with JIS P 8124. (2) Paper thickness and density Measurements were taken in accordance with JIS P 8118:2014. (3)ISO whiteness Measurements were taken using a Murakami Colori Co., Ltd. CMS-35SPX color difference meter, in accordance with JIS P 8148, under conditions including ultraviolet light. (4) Glossiness of white paper Measurements were taken in accordance with JIS P 8142. (5) Opacity Measurements were taken in accordance with JIS P 8149:2000.

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

[0041] (7)Print surface strength Using an RI-I type printing press (manufactured by Akira Seisakusho), printing was performed using printing ink (NEX-Y manufactured by Toyo Ink). After printing, 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 = Does not occur at all, B = Does not occur very often, C = Occurs slightly but does not affect usability, D = Too many to be usable

[0042] [Example 1] This paper uses 100% chemical pulp by weight and contains 13.5% by weight of light calcium carbonate as filler, with a basis weight of 45 g / m². 2 I prepared the original paper. 100 parts by weight of ultrafine heavy calcium carbonate (Fimatec, trade name: FMT100YF, D50=0.59μm), which is the first type of calcium carbonate, was used as the pigment. 5 parts by weight of styrene-butadiene copolymer latex and 6 parts by weight of oxidized starch were added to this as adhesives, and water was further added to obtain a coating solution for a pigment coating layer with a solid content of 65% by weight.

[0043] On the aforementioned base paper, apply a coating liquid for the pigment coating layer at a solid content of 10 g / m² per side. 2 The paper was coated on both sides using a blade coater, dried according to a standard method, and then calendered using resin and metal rolls to obtain coated paper for printing. This coated paper was evaluated using the method described above.

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

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

[0046] [Comparative Example 1] Printing coated paper was manufactured and evaluated in the same manner as in Example 1, except that 50 parts by weight of fine-grained heavy calcium carbonate (Fimatec, trade name: FMT97, D50=0.86μm), a secondary calcium carbonate, and 50 parts by weight of first-grade kaolin (Imeris Minerals Japan, trade name: Premier, D50=2.67μm) were used as pigments. [Comparative Example 2] Printable coated paper was manufactured and evaluated in the same manner as in Example 1, except that calendering was not performed. [Comparative Example 3] 4.5 g / m² of solids per side 2 Printable coated paper was manufactured and evaluated in the same manner as in Example 1, except that both sides were coated with a blade coater to achieve the desired result.

[0047] [Example 4] Printing coated paper was manufactured and evaluated in the same manner as in Example 1, except that ultrafine-grained caustic light calcium carbonate (manufactured by Nippon Paper Industries Co., Ltd., D50 = 0.64 μm) was used as the first calcium carbonate.

[0048] [Examples 5-7] Printing coated paper was manufactured and evaluated in the same manner as in Example 1, except that the mixing ratio of the first calcium carbonate and the second calcium carbonate was changed as shown in Table 1.

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

[0050] [Comparative Example 5] Printing coated paper was manufactured and evaluated in the same manner as in Comparative Example 4, except that the proportions of styrene-butadiene copolymer latex and oxidized starch were changed as shown in Table 1.

[0051] [Table 1]

[0052] The coated paper for printing of the present invention clearly exhibits excellent print surface texture and print surface strength. In particular, the coated paper for printing of Examples 3, 5, 6, and 7 clearly exhibits extremely excellent print surface texture and print surface strength. On the other hand, the coated paper for printing of the comparative examples does not exhibit sufficient print surface texture and print surface strength. In particular, the coated paper for printing of Comparative Example 4, which uses uniformly shaped calcium carbonate as the pigment for the outermost pigment coating layer, has low print surface strength due to the large amount of adhesive (binder) required. In the coated paper for printing of Comparative Example 5, in which the amount of adhesive (binder) was increased to compensate for this, the print surface strength improved, but the print surface texture decreased.

Claims

1. A coated paper for printing with a white gloss level (75°) of more than 40% but less than 60%, At least one side of the base paper should have a single-sided coating of 5 to 15 g / m². ２ It comprises a pigment coating layer, The outermost pigment coating layer is The first calcium carbonate is amorphous calcium carbonate having an average particle size (D50) of 0.80 μm or less, and the second calcium carbonate is heavy calcium carbonate or light calcium carbonate having an average particle size (D50) of more than 0.80 μm, and the adhesive contains starch and latex. In the outermost pigment coating layer, the total amount of the first and second calcium carbonates in 100 parts by weight of pigment is 90 parts by weight or more. The latex content is 10 to (5 / 11) × 100% by weight relative to 100% by weight of the adhesive. Coated paper for printing.

2. The coated paper for printing according to claim 1, wherein the average particle size (D50) of the amorphous calcium carbonate is 0.50 μm or more.

3. The printing coated paper according to claim 1 or 2, wherein the outermost pigment coating layer contains 10 parts by weight or more of the first calcium carbonate in 100 parts by weight of the pigment.

4. The coated paper for printing according to any one of claims 1 to 3, wherein the average particle size (D50) of the first calcium carbonate is 0.55 to 0.75 μm.

5. The printing coated paper according to any one of claims 1 to 4, wherein the outermost pigment coating layer contains 50 parts by weight or less of the first calcium carbonate in 100 parts by weight of the pigment.

6. The printing coated paper according to any one of claims 1 to 5, wherein the outermost pigment coating layer contains 30 parts by weight or less of the first calcium carbonate in 100 parts by weight of the pigment.

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