JP2006188800A - Coated paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated paper having excellent air-permeability and waterproofness, hardly causing generation of blisters at offset rotary printing and printing by an electrophotography method, hardly causing the generation of wrinkle by rotary printing, and having excellent cracking resistance at folding. <P>SOLUTION: The coated paper has a paper base material in a sheet shape, and at least one coated layer formed on one surface thereof, and containing a pigment and an adhesive as essential components. The pigment is kaolin particles having 0.1-1.5 μm average particle diameter and satisfying formula (1): 5≤L/W≤50 (wherein, L represents the major axis of the kaolin particle; and W represents the minor axis of the kaoline particle). The adhesive contains at least one kind selected from (a) a copolymer with a single structure, having 10-60°C Tg and (b) a macromolecular compound with a core-shell structure, and the coated layer contains at least one kind selected from a zirconium-based compound, a polyamide resin and an amine resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coated paper, and particularly to a coated paper that has excellent air permeability, can effectively suppress the generation of blisters during printing, and has a good print finish.

  Offset rotary printing (hereinafter also referred to as “off-wheel printing”), which is one form used for commercial printing, is performed by a dryer after printing paper is fed by winding and ink is transferred onto the paper. The ink is dried and taken up again. Further, it is folded by a folding machine. In either case, if the ink on the surface of the paper that has left the dryer is not completely dry, the surface of the paper or the printing machine may be stained, and a dryer set to extremely high temperature conditions is used. However, there is a case where a defect called blister occurs in the paper at that time.

  Blisters (called paper blisters) in this off-wheel printing are phenomena in which the vapor pressure rises due to the rapid vaporization of moisture in the paper, which causes a force in the thickness direction on the paper and creates voids due to delamination in the paper layer. Therefore, it is said that the cause is that moisture in the paper does not dissipate smoothly. For this reason, blisters are likely to occur particularly on printing paper having a coating layer with poor air permeability on the front and back. With the recent increase in printing speed, the drying temperature tends to be higher, and it is becoming difficult to suppress blistering. Among them, a high gloss printing paper obtained through a gloss imparting process using a super calender has a more dense coating layer, and thus becomes a coating layer with poor air permeability, and blisters are particularly likely to occur.

  Many proposals have been made for suppressing the occurrence of blisters in off-wheel printing. It can be broadly classified into two methods. The first is to increase the interlaminar strength of the coated paper sheet base material (hereinafter sometimes referred to as “base paper”) and to expand due to water vapor pressure. The second method is to prevent delamination against the above, and the second method is to improve the air permeability of the coating layer and to release the generated water vapor to reduce the vapor pressure.

  Various proposals have been made for improving the interlayer strength of the base paper. For example, a method of increasing the interlayer strength of the base paper to a specific value or more (for example, see Patent Document 1), a method of containing a specific amount of cationized starch and polyacrylamide in the base paper (for example, see Patent Document 2), etc. Some have been converted into However, the above-described method for improving the interlayer strength of the base paper is that when the air permeability of the coating layer formed on the base paper is high, the dissipation of water vapor is greatly hindered by the coating layer, so only the interlayer strength of the base paper is improved. Then, blister generation cannot be suppressed completely.

  Many proposals have also been made on methods for improving the air permeability of the coating layer. For example, among the undercoat layer and the overcoat layer, a method using a latex having a specific gel content in the undercoat layer (see, for example, Patent Document 3), using a specific pigment and binder, and using a surface-roughening roll A method of processing (for example, see Patent Document 4) and a method of applying latex having different glass transition temperatures (hereinafter referred to as “Tg”) on a sheet-like paper substrate or undercoat layer (for example, Patent Document 5). A method using kaolin having a specific aspect ratio (for example, see Patent Document 6), a method using superheated steam or the like for drying a coating layer containing a high Tg latex (for example, see Patent Document 7), etc. There is. However, when there are a plurality of coating layers, the thickness of the coating layer increases, so that it is difficult to achieve the desired air permeability. In addition, the production cost is high due to the multiple coating steps. In addition, when the surface-roughening process is performed, coated paper with high gloss cannot be obtained. In addition, when applying a latex having a different Tg on a sheet-like paper base material or an undercoat layer, it is necessary to control the drying conditions within a specific range, so that stable production is difficult, and only the latex is applied. For this reason, the coated paper has a problem of poor water absorption and inking during printing. Further, the use of kaolin having a specific aspect ratio has a limit to high glossiness, and a method using superheated steam or the like for drying a coating layer containing a high Tg latex is one form of a main printing method of commercial printing. Ink printing, which is called an ink set in flat printing, is extremely slow, and when there is no drying process during the printing process, the printing workability is greatly reduced, and stains caused by undried ink occur on the printed matter. There is a risk of reducing the print finish. As described above, although the effect can be seen in any case, the printing finish is good, and it is not always a sufficient level to cope with the recent increase in printing speed, and further improvement is desired. It was rare.

  In addition, the occurrence of blistering may also be a problem even in a printing method using a toner transfer method (so-called electrophotographic method), which is one of the forms of on-demand printing that has been attracting attention in recent years. There are two types of toner transfer type blisters, and one is a paper blister in which the paper is delaminated due to the vapor pressure generated by the evaporation of moisture in the paper, similar to the blister in off-wheel printing. The other is that when the solid toner transferred onto the paper is melted and solidified in the heat fixing unit, the air that exists between the toners cannot be passed through the coating layer and is smoothed. This is a toner blister that is generated by detaching from the surface of the layer. The toner blister peculiar to this toner transfer system is difficult to solve by the method of suppressing the occurrence of blistering in off-ring printing, and an effective solution has not yet been found.

  The voids present on the surface of the coating layer of general coated paper include fine voids (hereinafter referred to as “pores A”) that are not filled with other components between the pigment particles, and the drying process of the coating layer. Vapor permeation holes (hereinafter referred to as “pores B”) generated by rupture of the coating layer resulting from the brittleness of the coating layer film that cannot resist the tensile stress due to film shrinkage during drying (hereinafter referred to as “crack”). In order to fix the ink to the paper during printing (so-called ink set), absorption of the ink solvent due to the capillary phenomenon of the pores plays an extremely important role. Plays. The pore diameter of the pore A varies depending on the size of the pigment used, but is usually about 0.02 to 0.2 μm and greatly contributes to the ink set. Incidentally, there is a report that the pores most effective for the ink set are those having a pore diameter of about 0.12 to 0.15 μm (for example, see Non-Patent Document 1). It is very difficult to control the occurrence of the pore B, and in some cases, a circular hole with a size that can be visually discerned on a white paper or printed matter may be generated. Suppression of the occurrence is desired. The crack is usually produced so as to suppress the generation as much as possible in order to reduce the surface strength of the coating layer. Although it is known that cracks are generated on the surface of the coating layer by a method using latexes having different glass transition temperatures (for example, see Patent Document 5), it is difficult to produce stably as described above. As described in Patent Document 5, the crack size on the surface of the applied coating layer is estimated to be a size that can improve the ink set, that is, about 0.02 to 0.20 μm. Until now, it has not been proposed to effectively and stably generate a void having a size of 0.2 μm or more as defined in the present invention.

  As described above, in the prior art, it is difficult to control the voids existing on the surface of the coating layer, so that the generation of blisters in off-wheel printing and the generation of paper blisters and toner blisters in electrophotography are suppressed. A satisfactory coated paper was not obtained, and further improvement was desired.

JP 11-160906 A (2 pages) JP-A-6-25996 (page 2) JP-A-9-324395 (2 pages) JP-A-5-247891 (page 2) JP 59-22683 A (2 pages) JP 2000-226791 A (page 2) JP-A-8-158297 (page 2)

Tomoyuki Terao et al. “Effects of coating layer structure of coated paper on ink set”, Papa Gikyo Paper, Vol. 51, No. 9, pp. 79-85 (September 1997)

  An object of the present invention is to provide a coated paper that is excellent in air permeability and water resistance and does not generate blisters during off-wheel printing and electrophotographic printing. In addition, an object of the present invention is to provide a coated paper that is less likely to generate off-wheel wrinkles and has excellent breakability.

  As a result of intensive studies in view of the present situation, the present inventors have provided a coated paper having at least one coating layer, and in the coating layer, a pigment having a specific structure and a single structure are provided. It is particularly effective to contain a copolymer and / or a synthetic polymer compound having a core-shell structure, and at least one selected from a zirconium-based compound, a polyamide-based resin, and an amine-based resin. I found it.

The coated paper according to the present invention has a sheet-like paper base material and at least one coating layer formed on at least one surface thereof and containing a pigment and an adhesive as main components. Kaolin particles having an average particle size of 0.1 to 1.5 μm and satisfying the following formula (1):
5 ≦ L / W ≦ 50 (1)
[In the formula (1), L represents the major axis of the kaolin particles, and W represents the minor axis of the kaolin particles.]
The adhesive is selected from (a) a copolymer having a glass transition temperature of 10 to 60 ° C. and having a single structure, and (b) a synthetic polymer compound having a core-shell structure. The coating layer further contains at least one selected from a zirconium-based compound, a polyamide-based resin, and an amine-based resin.
Further, the coating layer is at least two layers, and in the inner coating layer adjacent to the sheet-like paper substrate, any one of acicular crystals, spindle crystals, columnar crystals, and rice granular crystals is used. In the outermost coating layer containing a pigment having a crystal structure and formed on the inner coating layer, the pigment has an average particle diameter of 0.1 to 1.5 μm, and the following formula ( Kaolin particles satisfying 1):
5 ≦ L / W ≦ 50 (1)
[In the formula (1), L represents the major axis of the kaolin particles, and W represents the minor axis of the kaolin particles.]
The adhesive is selected from (a) a copolymer having a glass transition temperature of 10 to 60 ° C. and having a single structure, and (b) a synthetic polymer compound having a core-shell structure. Those containing at least one kind are preferable, and the outermost coating layer preferably contains thermoplastic organic fine particles having a glass transition temperature of 20 to 150 ° C.
Furthermore, the glass transition temperature of the synthetic polymer compound (b) having the core-shell structure is represented by the following formulas (2) and (3):
Tg1 <Tg2 (2)
−10 ° C. <Tg2 <100 ° C. (3)
[In the formulas (2) and (3), Tg1 represents the glass transition temperature of the core portion in the synthetic polymer compound (b) having a core-shell structure, and Tg2 represents the glass transition temperature of the shell portion. It is preferable to satisfy
It is preferable that at least one selected from a zirconium compound, a polyamide resin, and an amine resin is contained in 0.01 to 10 parts by mass in 100 parts by mass of the coating layer.
The surface of the coated paper preferably has a glossiness of 45% or more, and the air permeability of the coated paper is preferably 7000 seconds or less.

  According to the present invention, it has excellent air permeability and water resistance, no blisters are generated at the time of printing or printing in off-wheel printing and electrophotography, and the print finish is good, and further no off-wheel wrinkles are generated. Coated paper that does not break is obtained.

  As a result of intensive studies in view of the present situation, the present inventors have provided a coated paper having at least one coating layer, and in the coating layer, a pigment having a specific structure and a single structure are provided. A copolymer (hereinafter also referred to as “single structure copolymer”) and / or a synthetic polymer compound having a core-shell structure (hereinafter also referred to as “core-shell structure polymer compound”). Furthermore, it has been found that containing at least one selected from a zirconium-based compound, a polyamide-based resin, and an amine-based resin is particularly effective and can be improved without impairing other aptitudes.

  The higher the smoothness of the coating layer surface, and thus the higher the glossiness, the better the adhesion between the coating layer surface and the printing plate, and the higher the ink transferability. In the present invention, an adhesive containing (a) a single structure copolymer having a glass transition temperature of 10 to 60 ° C. and / or (b) a core-shell structure polymer compound is blended in the coating layer. It was confirmed that the cushioning property of the coating film was high, the adhesiveness with the blanket during offset printing was high, and excellent printing quality was obtained. In the present invention, the core-shell structure polymer compound is a fine ball-shaped core portion made of a single polymer or copolymer, and a shell portion surrounding the core portion and made of a single polymer or copolymer. It is a copolymerized polymer compound having a composite structure. The single structure copolymer is a copolymer which is composed of a copolymer of two or more comonomers and does not have a composite structure such as a core-shell structure.

In the coated layer of the coated paper of the present invention, a single structure copolymer (a) having a glass transition temperature of 10 to 60 ° C., preferably 15 to 50 ° C., used as an adhesive (binder) is, for example, A styrene-butadiene copolymer, an acrylic copolymer, a styrene-acrylic copolymer, a vinyl acetate copolymer, an ethylene-vinyl acetate copolymer, or the like is selected. The single structure copolymer (a) having a glass transition temperature of 10 to 60 ° C., preferably 15 to 50 ° C., is 2 to 50 parts by weight, preferably 3 parts per 100 parts by weight (solid content) of the coating layer. -40 parts by weight, more preferably 3-25 parts by weight. If it is less than 2 parts by weight, the coating film strength is insufficient, and the blanket may become dirty during off-wheel printing. On the other hand, when the amount exceeds 50 parts by weight, the air permeability is remarkably lowered and blisters may be generated.

The core-shell structure polymer compound (b) used in the present invention has the following formulas (2) and (3):
Tg1 <Tg2 (2)
−10 ° C. <Tg2 <100 ° C. (3)
[In the formulas (2) and (3), Tg1 represents the glass transition temperature of the core portion in the core-shell structure polymer compound (b), and Tg2 represents the glass transition temperature of the shell portion. ] Is preferable. That is, in this preferred embodiment, the glass transition temperature Tg2 of the shell part is higher than the glass transition temperature Tg1 of the core part, and the glass transition temperature Tg2 of the shell part is higher than −10 ° C. and less than 100 ° C. For this reason, the surface of the film formed of the core-shell structure polymer compound is formed by a shell portion having a glass transition temperature Tg2. After the coating layer is formed, the (Tg1) core portion having a low glass transition temperature is surrounded by a shell portion having a high glass transition temperature (Tg2), and exhibits high flexibility, flexibility and elasticity at room temperature. When the external pressure is removed, the polymer compound core part in the coating film is easily deformed with respect to the external pressure, and returns to the original shape and exhibits high cushioning properties. Therefore, the printing plate and the coating layer are brought into close contact with each other by pressing during printing and exhibit good ink transfer properties. Incidentally, when the glass transition temperature Tg2 of the shell part of the core-shell structure polymer compound (b) is 100 ° C. or more, the film formability may be insufficient. On the other hand, when the glass transition temperature Tg2 of the shell portion is −10 ° C. or lower, the resulting coating film is sticky and blocking is likely to occur. The glass transition temperature Tg2 of the shell part is more preferably in the range of 0 ° C to 75 ° C. In particular, the glass transition temperature Tg2 of the shell part is preferably 5 ° C. or more higher than the glass transition temperature Tg1 of the core. When this temperature difference is less than 5 ° C., the cushioning property of the coating layer becomes insufficient, and the effect of preventing missing dots may be insufficient. The core-shell structure polymer compound (b) used in the present invention is available as a core-shell type copolymer latex, and the latex preferably has a particle diameter of 40 to 300 nm. If it exceeds 300 nm, the strength of the coating film may be insufficient. Further, the toluene-insoluble content of the core-shell structure polymer compound (b) is preferably 30% or more. If it is less than 30%, the polymer compound may swell in the resulting coating layer due to the solvent of the ink, and the mechanical strength of the coating layer may be insufficient. The core-shell structure polymer compound (b) is blended in an amount of 2 to 50 parts by weight, preferably 3 to 40 parts by weight, more preferably 3 to 25 parts by weight, based on 100 parts by weight (solid content) of the coating layer. The If it is less than 2 parts by weight, the coating film strength is insufficient, and the blanket may become dirty during off-wheel printing. On the other hand, when the amount exceeds 50 parts by weight, the air permeability is remarkably lowered and blisters may be generated.

  Methods for producing the core-shell structured polymer compound (b) latex are disclosed in JP-A-62-117897, JP-A-7-324112, JP-A-9-31141 and the like.

  The latex of the core-shell structure polymer compound (b) contains a core copolymer component having a low glass transition temperature Tg1 and a shell copolymer component having a high glass transition temperature Tg2 in the same latex. As a result, the desired film performance can be obtained. That is, in the coated paper of the present invention, when the core-shell structured polymer compound latex is used as a coating layer adhesive (binder), the polymer contained in the coating layer adhesive (binder) component. Since the compound has a copolymer component having a low glass transition temperature in its core, it exhibits cushioning properties against printing press applied to the coated paper during printing, and the coated paper surface is against the printing plate. It can be sufficiently adhered.

  As a result of intensive studies to prevent or reduce the occurrence of blisters, the present inventors have defined as the ratio of the plane major axis L to the minor axis W of the pigment particles as the main component of the pigment contained in the coating layer. The aspect ratio is in the range of 5 to 50, preferably in the range of 5 to 15, and the average particle diameter is in the range of 0.1 to 1.5 μm, preferably in the range of 0.2 to 1.2 μm. By using a certain kaolin, and further containing this kaolin in 100 parts by mass of the total pigment, preferably 30 parts by mass or more, preferably 35 parts by mass or more, high gloss, high smoothness and low air permeability can be obtained. A coating layer was obtained, and the generation of blisters was successfully reduced. Incidentally, even if the average particle diameter of kaolin is 0.1 to 1.5 μm, when the aspect ratio is less than 5, it is difficult to obtain sufficient glossiness in the obtained coating layer, and the smoothness also decreases. Therefore, a good print finish may not be obtained. On the other hand, when the aspect ratio exceeds 50, the glossiness of the obtained coating layer is sufficiently high, but the air permeability is also high, so that the generation of blisters cannot be prevented or reduced.

  The reason why the kaolin used in the present invention is effective for forming a coating layer having high smoothness, high gloss, and low air permeability is that the aspect ratio of kaolin is in the range of 5 to 50 and is generally used. Compared to delaminated kaolin with an aspect ratio exceeding 50, the ratio of the minor axis is a relatively large shape, the average particle size is as small as 0.1 to 1.5 μm, and the hexagonal plate shape has a uniform particle size distribution This is because, after the coating layer is smoothed, the gap between the laminated pigments does not have a dense structure, and has high flatness that is characteristic of hexagonal plate kaolin. Guessed.

  When the average particle diameter of the pigment having an aspect ratio in the range of 5 to 50 is smaller than 0.1 μm, the resulting coating layer tends to have high gloss, but the air permeability is remarkably lowered. On the other hand, if it exceeds 1.5 μm, it is difficult to obtain high gloss on the resulting coating layer, and the desired glossiness cannot be obtained. As for the particle size distribution, it is preferable that the distribution frequency of particles having a particle diameter of 0.1 to 1.5 μm is 65% or more.

  In the coated paper of the present invention, the content of kaolin used as the main component of the pigment in the coating layer is preferably 30 parts by mass or more with respect to 100 parts by mass of the total pigment in the coating layer, More preferably, it is in the range of 35 parts by mass to 100 parts by mass. If it is less than 30 mass parts, the air permeability of the obtained coating layer may become inadequate.

In addition, the inner coating layer is coated with a pigment having a crystal structure of any one of acicular crystals, spindle crystals, columnar crystals, and rice granular crystals, imparting crease resistance to the coated paper and providing air permeability. It is easy to obtain a coating layer having it and is preferably used.
Means a fine pigment having a crystal structure of any one of acicular crystals, spindle-shaped crystals, columnar crystals and rice granular crystals constituting the inner coating layer, for example, at least one of phosphoric acid and water-soluble salts thereof A method of reacting a calcium hydroxide suspension having a specific concentration with a carbon dioxide gas-containing gas (Japanese Examined Patent Publication No. 57-30815), and reacting in the presence of at least one of a specific carboxylic acid and a water-soluble salt thereof. Method (Japanese Examined Patent Publication No. 57-31530), carbon dioxide containing gas is introduced into a water suspension containing a specific needle columnar crystal nucleus calcium carbonate and calcium hydroxide at a specific temperature, and a carbonation reaction is performed. It is produced by a method of obtaining a calcium bundle (Japanese Patent Laid-Open No. 59-232916) or the like.
The fine particle pigments having these crystal structures have an average dimension observed by observation with an electron microscope of a minor axis dimension (W) of 0.005 to 0.5 μm, a major axis dimension (L) of 0.1 to 10 μm, and an aspect ratio (L / W) Any one of acicular crystals, spindle-shaped crystals, columnar crystals, and rice granular crystals having a molecular weight of 2 to 1000, which are appropriately selected and used.

In the coated paper according to the present invention, it is preferable that cracks having a width of 0.2 to 3.0 [mu] m and a length of 3 to 1000 [mu] m are present in an amount of about 1 to 1000 per mm < ² > for suppressing the generation of blisters. When printing on coated paper having such cracks, it is very difficult to visually confirm the cracks on the printed matter, and a good print finish is obtained. In addition, it is preferable that a crack exists independently without connecting. If cracks are connected, the printing strength may be inferior, which is not preferable.

  Although the component of the coating layer of this invention will not be specifically limited if the said crack is obtained, A thermoplastic organic fine particle can be mentioned as a preferable material. Among these, thermoplastic organic fine particles whose surface or the whole is softened under the coating and drying conditions are preferable. Further, Tg (glass), which has a higher film forming temperature than latex generally used as an adhesive for coated paper, is preferable. (Transition temperature) Thermoplastic organic fine particles made of a resin having a temperature in the range of 20 to 150 ° C. are excellent in terms of crack generation, and more preferable. Especially, the thing of the range whose Tg is 20-80 degreeC is preferable on the balance of a desired crack generation effect and printing strength, and the thing of the range which is 30-80 degreeC is especially preferable. When Tg is less than 20 ° C., the occurrence of cracks is small and the air permeability is inferior when viewed from the intended level, and the blistering suppression effect may be inferior. If Tg exceeds 150 ° C., the printing strength may be lowered under normal drying conditions, which is not preferable.

  In the present invention, a Tg of 20 to 150 ° C. is used rather than a single type of thermoplastic organic fine particles made of a resin having a Tg of 20 to 150 ° C. in the coating layer or the outermost coating layer. A system using two or more kinds of thermoplastic organic fine particles having different film forming conditions and made of a resin in a temperature range is more preferable. Examples of the thermoplastic organic fine particles used in the present invention include non-homogeneous structured fine particles such as core-shell fine particles, in addition to normal fine particles which are homogeneous as a whole. In the case of core-shell type fine particles, the Tg of the resin on the shell side is important and is preferably in the range of 20 to 150 ° C. However, although the performance of the obtained coated paper is inferior, one having a Tg of 20 ° C. or lower can be used. Specifically, what is called a binder pigment is mentioned.

  Examples of the thermoplastic organic fine particles include polydienes such as polyisoprene, polyneoprene, and polybutadiene, polyalkenes such as polybutene, polyisobutylene, polypropylene, and polyethylene, vinyl halide, vinyl acetate, styrene, (meth) acrylic acid, (meta ) Vinyl polymers and copolymers such as acrylic ester, (meth) acrylamide, methyl vinyl ether, synthetic rubber latexes such as styrene-butadiene and methyl methacrylate-butadiene, polyurethane resins, polyester resins, polyamides Resin, olefin-maleic anhydride resin, vinylidene chloride resin and the like. One or more of these are appropriately selected and used.

  As a compounding quantity to the coating liquid of the said thermoplastic organic fine particle, the range of 5-60 mass parts is preferable with respect to 100 mass parts (solid content) of a coating layer. When the blending amount is less than 5 parts by mass, the generation of cracks cannot be promoted, the air permeability is high, and the effect of suppressing the generation of blisters may be inferior. On the other hand, when the blending amount exceeds 60 parts by mass, the resin component in the coating layer increases, and the ink vehicle absorbability is poor, so that ink transfer failure is likely to occur, and the texture as coated paper is further reduced. Therefore, it is not preferable.

  In addition to the above-mentioned thermoplastic organic fine particles, a pigment can be blended in the coating layer of the present invention as necessary. Examples of the pigment include known inorganic pigments and organic pigments other than the thermoplastic organic fine particles. Examples of inorganic pigments include heavy calcium carbonate, light calcium carbonate, kaolin, calcined kaolin, structural kaolin, delaminated kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, alumina, magnesium carbonate, magnesium oxide, and silica. , Magnesium aluminosilicate, calcium silicate, white carbon, bentonite, zeolite, sericite, smectite and the like. Examples of organic pigments include polystyrene resins, styrene-butadiene copolymer resins, styrene-acryl copolymer resins, styrene-methacryl copolymer resins, acrylic resins, vinylidene chloride resins, urea resins, and melamine resins. Examples thereof include resins and benzoguanamine resins. Examples of the organic pigment include a solid type, a hollow type, a through-hole type, and a core / shell type. One or more of these are appropriately selected and used. Among them, hollow organic pigments are easily deformed by pressure, and when gloss is imparted by a smoothing process such as super calender, a desired gloss can be obtained at a lower processing pressure, and the pores of the coating layer are reduced. Is preferably used because it exhibits a good air permeability. In addition, as a compounding quantity to the coating liquid of a hollow organic pigment, 20 mass parts or less are preferable with respect to 100 mass parts (solid content) of a coating layer, and 1-10 mass parts is more preferable. When the amount exceeds 20 parts by mass, an opacity reduction phenomenon called calendar burning or blacking may occur in a smoothing process such as super calendering.

As a compounding quantity to the coating liquid of the said inorganic pigment, the range of 40-90 mass parts is preferable with respect to 100 mass parts (solid content) of a coating layer. When the blending amount is less than 40 parts by mass, the generation of cracks cannot be promoted, the air permeability is high, and the blister generation suppressing effect is considerably inferior. Moreover, when a compounding quantity exceeds 90 mass parts, surface strength is inferior and stable printing cannot be performed.
Among them, particularly good cracks are obtained when a coating layer coating liquid comprising a composition containing an inorganic pigment in the range of 40 to 90 parts by mass and a thermoplastic organic fine particle in the range of 5 to 60 parts by mass is used. Therefore, it is preferable.

  If necessary, an adhesive and crack formation promoting particles are further added to the coating solution for the coating layer or the outermost coating layer used in the present invention. The adhesive is used for increasing the surface strength of the coating layer and imparting good printability. The crack formation promoting particles are blended when the crack formation does not reach a desired level.

  As the adhesive, a water-soluble or water-dispersible polymer compound can be used, for example, cationic starch, amphoteric starch, oxidized starch, enzyme-modified starch, thermochemically-modified starch, esterified starch, etherified starch, etc. Starches, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, natural or semi-synthetic polymer compounds such as gelatin, casein, soy protein, natural rubber, polydienes such as polyvinyl alcohol, polyisoprene, polyneoprene, polybutadiene, polybutene, poly Polyalkenes such as isobutylene, polypropylene, and polyethylene, vinyl halides, vinyl acetate, styrene, (meth) acrylic acid, (meth) acrylic acid esters, (meth) acrylamide, methyl vinyl ether and other vinyl polymers and copolymers, Styling -Synthetic polymer latex such as butadiene-based, methyl methacrylate-butadiene-based synthetic rubber latex, polyurethane-based resin, polyester-based resin, polyamide-based resin, olefin-maleic anhydride-based resin, melamine-based resin, etc. . One type or two or more types of adhesives are appropriately selected as necessary. Among the adhesives, an adhesive having a Tg of 20 ° C. or less is preferable, and particularly preferably 0 ° C. or less. As a compounding quantity to the coating liquid of an adhesive agent, 15 mass parts or less are preferable with respect to 100 mass parts (solid content) of a coating layer. When the amount exceeds 15 parts by mass, the generation of cracks is hindered, making it difficult to obtain the desired effect of the present invention.

  In the coating solution for the coating layer or the outermost coating layer used in the present invention, various auxiliary agents such as a surfactant, a pH regulator, a viscosity modifier, a water retention agent, a softening agent are further added as necessary. , Gloss imparting agents, waxes, dispersants, flow modifiers, antistatic agents, stabilizers, antistatic agents, crosslinking agents, sizing agents, fluorescent brighteners, colorants, UV absorbers, antifoaming agents, water resistance Agents, plasticizers, preservatives, fragrances and the like are appropriately blended.

  As the water retention agent, it is preferable to use a cellulose derivative such as carboxymethyl cellulose or hydroxyethyl cellulose, or a synthetic water retention agent such as an alkali swelling acrylic thickener.

  About the pulp which forms the sheet-like paper base material used for this invention, it does not specifically limit about a manufacturing method or a kind, Mechanical pulp, such as chemical pulp like KP and SP, SGP, RGP, BCTMP, and CTMP, , Chlorine-free pulp such as ECF pulp and TCF pulp, waste paper pulp such as deinked pulp, or non-wood pulp such as kenaf, bagasse, bamboo, straw, hemp, etc., organic such as polyamide fiber, polyester fiber, polynosic fiber Examples thereof include synthetic fibers, and inorganic fibers such as glass fibers, ceramic fibers, and carbon fibers.

  In the sheet-like paper substrate, a filler, a yield improver, a freeness improver, a paper strength enhancer, a fixing agent, an internal sizing agent, a dye, a fluorescent whitening agent, a pH adjuster, an eraser are optionally added. Internal additives for papermaking such as foaming agents, pitch control agents, slime control agents and the like can be appropriately blended. The filler is not particularly limited, but various pigments generally used for fine paper, such as kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, carbonate Organic pigments such as mineral pigments such as magnesium, magnesium oxide, silica, white carbon, bentonite, zeolite, sericite, smectite, polystyrene resins, urea resins, melamine resins, acrylic resins, vinylidene chloride resins Solid, micro hollow, and through-hole type particles.

The paper-making method of the sheet-like paper base is not particularly limited, and includes, for example, an acidic paper-making method having a paper-making pH of around 4.5, and a neutral sizing agent and / or an alkaline filler such as calcium carbonate as a main component. It can be applied to all papermaking methods, from weakly acidic papermaking pH of about 6 to weak alkaline neutral papermaking of papermaking pH of about 9, and the paper machine is also a long net paper machine, twin wire paper machine, round net paper machine A known paper machine such as a machine, a Yankee paper machine, or an inclined wire paper machine can be used as appropriate.
Although the basic weight of the sheet-like paper base material used for this invention is not specifically limited, Usually, the thing of the range of 30-300 g / m < ² > is used preferably.

  The paper-making method of the sheet-like paper base is not particularly limited, but even if the air permeability of the coating layer is good, the sheet-like paper base is extremely poor in air permeability, and the effect of suppressing the generation of blisters May not be obtained. Therefore, the JAPAN TAPPI paper pulp test method no. The air permeability based on 5-2: 2000 is preferably 30 seconds or less, and more preferably 20 seconds or less.

Although the total coating amount of the coating layer of this invention is not specifically limited, It is 2-25 g / m < ² > by dry mass with respect to the single side | surface of a sheet-like paper base material, Preferably it is 5-20 g / m < ² >. is there. When the coating amount is less than ² g / m ² , it may be difficult to form a coating layer uniformly on the sheet-like paper substrate. On the other hand, when the coating amount exceeds 25 g / m ² , the air permeability is reduced. It may become high, and the generation of cracks due to shrinkage of the coating layer may be difficult to occur.

  The inner coating layer of the present invention is formed by applying an aqueous coating solution containing an inorganic pigment and a water-soluble adhesive as components to a sheet-like paper base material. The inorganic pigment has a crystalline structure. In addition to the pigment having, for example, heavy calcium carbonate, light calcium carbonate, kaolin, calcined kaolin, structural kaolin, delaminated kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, alumina, magnesium carbonate, magnesium oxide, Examples thereof include silica, magnesium aluminosilicate, calcium silicate, white carbon, bentonite, zeolite, sericite, smectite, etc., which are appropriately selected from these and used in combination of one or more.

  You may mix | blend an organic pigment as another pigment in the coating liquid for inner side coating layers. Examples of the organic pigment include polystyrene resin, styrene-butadiene copolymer resin, styrene-acryl copolymer resin, styrene-methacryl copolymer resin, acrylic resin, vinylidene chloride resin, urea resin, and melamine. Resin, benzoguanamine resin, and the like, which are appropriately selected from these and used in combination of one or more.

  As a compounding quantity to the coating liquid for inner side coating layers of an inorganic pigment, the range of 35-95 mass parts is preferable with respect to 100 mass parts (solid content) of coating layers. When the blending amount is less than 35 parts by mass, it tends to be inferior in terms of air permeability. Moreover, when a compounding quantity exceeds 95 mass parts, it will become inferior in terms of interlayer strength. Moreover, as a compounding quantity to the coating liquid for inner side coating layers of an organic pigment, 30 mass parts or less are preferable with respect to 100 mass parts (solid content) of coating layers. It is not preferable to exceed 30 parts by mass in terms of coating solution cost.

  Examples of the adhesive in the inner coating layer include starches such as starch, oxidized starch, esterified starch, etherified starch, cationized starch, amphoteric starch, enzyme-modified starch, thermochemically modified starch, methylcellulose, carboxymethylcellulose, Examples include cellulose derivatives such as hydroxyethyl cellulose, proteins such as casein and soy protein, water-soluble adhesives such as polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, and olefin-maleic anhydride resin. These are appropriately selected from these and used alone or in combination of two or more. Among water-soluble adhesives, starches are particularly preferable because they are easy to impart rigidity and are inexpensive.

  As an adhesive in the inner coating layer, a water dispersible adhesive may be blended. Such water-dispersible adhesives include conjugated diene copolymer latexes such as styrene-butadiene latex, acrylonitrile-butadiene latex, methyl methacrylate-butadiene latex, and acrylics such as (meth) acrylic acid ester polymers or copolymers. Emulsion, vinyl acetate emulsion such as ethylene-vinyl acetate emulsion, styrene-acrylic emulsion, vinylidene chloride emulsion, polyester emulsion, polyurethane emulsion, polyamide emulsion, and the like. One type or two or more types are used in combination.

  As a compounding quantity to the coating liquid for inner side coating layers of a water-soluble adhesive, the range of 2-25 mass parts is preferable with respect to 100 mass parts (solid content) of coating layers. When the blending amount is less than 2 parts by mass, the interlayer strength tends to be inferior, and the rigidity is likely to be small. Moreover, when a compounding quantity exceeds 25 mass parts, it becomes easy to become a thing with high air permeability. As a compounding quantity to the coating liquid for inner side coating layers of a water dispersible adhesive agent, 20 mass parts or less are preferable with respect to 100 mass parts (solid content) of coating layers. When it exceeds 20 parts by mass, it tends to have a high air permeability.

By adding one or more water-proofing agents in combination, the water resistance of the coating layer is improved, and the coating when dampening water adheres and the coated paper surface gets wet in the offset printing process. Suppresses the decrease in surface strength of the layer. Accordingly, even when the ink is transferred to the image line portion, it is possible to effectively suppress the occurrence of printing defects in the image line portion and smearing of the blanket caused by the coating layer peeling off and adhering to the blanket. The water-proofing agent can be appropriately selected from known ones. Among these, a material that imparts water resistance by a crosslinking reaction is preferable. Zirconium compounds can be preferably used because they react quickly in the coating process and develop water resistance. Examples of zirconium-based compounds include ammonium zirconium carbonate, ammonium zirconium acetate, ammonium zirconium sulfate, ammonium zirconium nitrate, zirconium ammonium iodide, zirconium ammonium fluoride, zirconium ammonium oxychloride, zirconium ammonium oxyiodide, and the like. Of these, ammonium zirconium carbonate is preferably used because it is excellent in terms of handling and water resistance. Incidentally, the zirconium-based compound shows high reactivity with a carboxylic acid, an ester group or the like, and can be preferably used together with an olefin resin, a styrene resin, an alkyd resin, a styrene-acrylic resin, and the like.
The compounding amount of the zirconium-based compound is not limited as long as the desired effect is expressed, but the effect is exhibited by containing 0.01 to 10 parts by mass of the zirconium-based compound in 100 parts by mass of the coating layer. Is done. If the amount is less than 0.01 parts by mass, the water resistance effect may not be exhibited. On the other hand, when the amount exceeds 10 parts by mass, the fluidity of the coating liquid becomes poor, resulting in difficulty in coating properties, or the effect is saturated, and no further water resistance effect is exhibited, resulting in high costs. .

The coating layer of the present invention preferably contains a polyamide-based resin or an amine-based resin as a material that enhances air permeability. As the amine-based resin, Sumire Resin SPI-102A manufactured by Sumika Chemtech Co., Ltd., which is a modified amine-based resin, is used. Examples of polyamide resins include Sumire Resin 633 manufactured by Sumika Chemtech Co., and Sumire Resin SPI-106N which is a modified polyamide resin.
Here, although the mechanism for improving the air permeability is not clear, the polyamide-based resin or the amine-based resin is slightly cationic and has a thickening effect when dried even if the concentration of the coating layer is low. It is presumed that the immobilization of the coating layer is accelerated, and the portion dehydrated by drying contributes to air permeability.
The blending amount of the polyamide resin or amine resin is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the pigment. Incidentally, if the blending amount of the polyamide-based resin or the amine-based resin is less than 0.01 parts by mass, the air permeability may not be improved. On the other hand, when the amount exceeds 10 parts by mass, the paint becomes unstable, and there may be a problem in operability such as the occurrence of streaks.

  In the coating liquid for the inner coating layer, various auxiliary agents such as surfactants, pH regulators, viscosity modifiers, water retention agents, softeners, gloss-imparting agents, waxes, dispersants are added as necessary. , Flow modifier, antistatic agent, stabilizer, antistatic agent, cross-linking agent, sizing agent, fluorescent brightener, colorant, ultraviolet absorber, antifoaming agent, water-resistant agent, plasticizer, preservative, fragrance Etc. are appropriately blended.

The coating amount of the inner coating layer and the outermost coating layer is not particularly limited, but in the case of the inner coating layer, it is usually 0.1 to 10 g / m ² , preferably 0 in terms of dry mass per side. 0.5 to 5 g / m ² . When the amount is less than 0.1 g / m ² , the effect of the two layers becomes extremely small. On the other hand, when the amount exceeds 10 g / m ² , the gas permeability tends to be inferior. In the present invention, the inner coating layer is provided on one side or both sides of the sheet-like paper substrate. Further, the number of inner coating layers per side is usually one layer, but it may be a laminate of two or more layers. In this case, the coating liquids for forming the inner coating layer are not necessarily the same, and may be different according to desired performance requirements.

  As a coating method for the coating layer coating liquid of the present invention, generally known coating apparatuses such as blade coaters, air knife coaters, roll coaters, reverse roll coaters, bar coaters, curtain coaters, slot die coaters, gravure coaters, A Champlex coater, a brush coater, a slide bead coater, a die coater, a two-roll or metering blade type size press coater, a bill blade coater, a short dwell coater, a gate roll coater, and the like are used. A flat coating method in which unevenness due to fibers on the surface of the base paper is covered and flattened is preferable to a contour coating method in which a uniform thickness is applied on the base paper. Drying when the thermoplastic organic fine particles are blended in the coating liquid is preferably performed under conditions where the paper surface temperature is higher than the Tg of the thermoplastic organic fine particles.

  The coated paper of the present invention is usually subjected to a smoothing treatment. The smoothing process is performed on-machine or off-machine using a known apparatus such as a super calendar, a gloss calendar, or a soft calendar. The processing conditions such as the pressure of the pressure device, the heating temperature, and the number of nips are appropriately adjusted. In the present invention, since the generated cracks are considerably large and many in comparison with the size of cracks normally observed in general printing coated paper, the cracks are also blocked by gloss treatment such as super calender. And good air permeability can be provided.

  Paper blisters and toner blisters in the electrophotographic system are coated with JAPAN TAPPI paper pulp test method No. By setting the Oken air permeability based on 5-2: 2000 to 7000 seconds or less, the desired level can be achieved. Especially, 5000 seconds or less are preferable, More preferably, it is 3000 seconds or less, More preferably, it is 2000 seconds or less.

  In the present invention, in terms of the texture of the coated paper, it is preferred that the white paper glossiness at an incident / light-receiving angle of 75 degrees based on JIS Z 8741 is 45% or more, and 50 to 85%, more preferably 55. ~ 85%.

  In order to obtain a coated paper with a high incidence of white paper with an incident / light-receiving angle of 75 degrees according to JIS Z 8741, smoothing processing under high pressure conditions is required. Although the pores are blocked and only those with poor air permeability can be obtained, the coated paper according to the present invention contributes to cracks and can ensure air permeability even if smoothing treatment is performed under high pressure conditions, blistering Can be suppressed.

  When the coating layer is provided on one side of the sheet-like paper substrate, a coating layer can be provided on the back side for preventing curling, imparting printability, imparting paper supply / discharge, imparting antistatic properties, and the like. The back surface can be post-processed to impart properties such as adhesion, heat-sensitive recording, magnetic recording, flame retardancy, heat resistance, water resistance, oil resistance, and slip resistance. In addition, post-processing such as a thermal transfer receiving layer and an ink jet recording layer can be performed.

  The water content of the coated paper of the present invention is usually adjusted to a range of 3 to 10%. More preferably, it is 4 to 8% of range. When the water content is less than 3%, curling occurs on the coated paper, and stable printing cannot be performed. If the water content exceeds 10%, blisters are extremely likely to occur.

  The coated paper obtained in the present invention has extremely good performance as an offset printing or electrophotographic paper, but can also be used as an image recording paper such as a thermal transfer system or an ink jet system.

  In particular, in an electrophotographic system in which an image is formed with toner particles of about 5 to 7 μm, an extremely high quality image can be obtained by using the above-mentioned coated paper. For example, when an image is formed and evaluated using an electrophotographic printer based on a method in conformity with ISO-13660 draft standard QEA (Quality Engineering Associates, Inc.), a mottle at a tile size of 40 μm is 10 GSV (Gray Scale). (Value) or less, the line ragedness (jaggedness) is 10 μm or less, and the brilliance (blurring degree) is 11 μm or less, and an extremely good image can be obtained.

  It has been found that the coated paper of the present invention has a great effect on prevention of off-wheel wrinkles and resistance to folding. Off-wheel wrinkles are wrinkles on the paper that occur during off-wheel printing, and fold resistance is the resistance to cracking of the ink layer at the fold or trough in the folding machine processing after off-wheel printing. It is sex. The reason why the off-wheel wrinkle has a great effect is that, since the air permeability of the paper is low, the evaporation of water contained in the drying process of the off-wheel printing occurs uniformly, and therefore there is no variation in paper moisture. It is possible that the paper is not distorted and wrinkles are unlikely to occur. In addition, the reason why there is a great effect on the resistance to cracking is that the coated paper has a strong surface strength for its low air permeability, and even if force is applied by folding, the coated layer is destroyed. As a result, it is considered that the ink layer is hardly cracked. In addition, with respect to off-wheel wrinkles and crack resistance, a system in which a binder and a binder pigment are further blended shows particularly good results.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these ranges. In the examples, “parts” and “%” indicate “parts by mass (solid component)” and “mass%” unless otherwise specified. In addition, when the measured Tg is not a single peak, the main peak temperature or Tg calculated from the monomer composition is indicated as “Tg representative value”, and when the measured Tg is a single peak, the measurement is performed. The value or Tg calculated from the monomer composition is shown as “Tg value”.

Example 1
[Preparation of sheet-like paper substrate]
To a pulp slurry of 90 parts of LBKP (freeness (CSF) = 450 ml) and 10 parts of NBKP (freeness (CSF) = 450 ml), light calcium carbonate (PC: manufactured by Shiroishi Calcium Co., Ltd.) was added so as to be 5 parts. Paper is made on a long paper machine using a stock containing 1.5 parts of starch, 0.1 part of alkenyl succinic anhydride and 0.6 part of sulfuric acid band per 100 parts of pulp, and starch is applied during the paper making process. It is applied and dried with a size press so that the work amount is 1 g / m ^{2 in} dry weight, and smoothed with a machine calendar so that the Beck smoothness is 30 seconds, and the basis weight is 60 g / m ² . A sheet-like paper substrate was obtained.

[Preparation of coating solution]
Hydra gloss 90 (component: kaolin, average particle size 0.26 μm, aspect ratio 6, manufactured by Huber) 35 parts of water and dispersant (trade name: Aron A-9, manufactured by Toagosei Co., Ltd.) In addition, it was dispersed with a Coreless disperser to obtain a kaolin dispersion having a solid content of 72%. To this dispersion, 35 parts of FMT-97 having a solid content of 75% (component: heavy calcium carbonate, manufactured by Phimatech) was added as a solid content to prepare 35 parts of pigment slurry. Carboxymethylcellulose (trade name; AG Gum HE No. 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.3 parts to this pigment slurry, POT-7092 (Tg; 35 ° C., Nippon Zeon Co., Ltd.) as a styrene-butadiene copolymer latex 10 parts) and 20 parts of synthetic resin 0640 (Tg; 55 ° C., manufactured by JSR), 0.05 parts by mass of zirconium carbonate ammonium salt (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) as a reactive water-resistant agent Was added and stirred, and water was further added to prepare a coating solution having a solid concentration of 55%.

[Formation of coating layer on the surface of sheet paper]
The coating solution obtained above is coated on both sides at 500 m / min using a blade coater so that the dry weight per side of the sheet-like paper substrate is 12 g / m ^2, and then dried with hot air at 160 ° C. The coated paper having a basis weight of 84 g / m ² was obtained by passing the paper through a pressure nip composed of a metal roll and an elastic roll so that the gloss of the blank paper was 50%.

Example 2
[Preparation of coating solution for inner coating layer]
Spindle-shaped light calcium carbonate (trade name: TP221GS, manufactured by Okutama Kogyo Co., Ltd.) 85 parts, water-soluble adhesive oxide starch (trade name: Ace A, manufactured by Oji Constarch Co., Ltd.) 10 parts, high styrene-butadiene core shell structure 5 parts of molecular compound T-2540A (Tg1 / Tg2: −22 ° C./0° C., manufactured by JSR), 0.05 ppm of zirconium carbonate ammonium salt (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) as a reactive water-resistant agent Mass parts were added, and water was further added to prepare a coating solution having a solid concentration of 45%.
[Formation of inner coating layer]
The sheet-like paper base material obtained in Example 1 at a coating speed of 500 m / min using a gate roll coater so that the dry coating amount per side of the coating liquid is 2.0 g / m ^2. The inner coating layer-formed paper was obtained.
[Preparation of coating solution for outermost coating layer]
Kaolin (trade name: Hydra gloss 90, average particle size 0.26 μm, aspect ratio 6, manufactured by Huber) 50 parts in water, 0.01 parts of dispersant (trade name: Aron A-9, manufactured by Toagosei Co., Ltd.) And dispersed with a Coreless disperser to obtain a kaolin dispersion having a solid concentration of 72%. To this dispersion, 15 parts of heavy calcium carbonate having a solid content concentration of 75% (trade name; FMT-97, manufactured by Phimatech) was added in solid content to prepare a pigment slurry. To this pigment slurry, 0.3 g of carboxymethylcellulose (trade name; AG Gum HE No. 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and Tg 55 ° C. thermoplastic organic fine particles (trade name; trade name; 0640, manufactured by JSR) 30 parts, styrene-butadiene-based core-shell structure polymer compound T-2540A (Tg1 / Tg2: −22 ° C./0° C. manufactured by JSR) 5 parts, zirconium carbonate ammonium salt as a reactive water-resistant agent 0.05 parts by mass of (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) was added and stirred, and water was further added to prepare a coating solution having a solid content concentration of 55%.

[Creation of laminated coated paper]
The coating solution for the outermost coating layer was so prepared that the dry coating amount per side was 9.0 g / m ² .
Using a blade coater, coating is performed on both sides of the inner coating layer-formed paper at a coating speed of 500 m / min, and then processing is performed in a pressure nip composed of a metal roll and an elastic roll. %, A coated paper having a basis weight of 82 g / m ² was obtained.

Example 3
In Example 1, zirconium carbonate ammonium salt (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) was increased to 3 parts by mass, and styrene-acrylic resin (trade name; Polymaron 1308, manufactured by Arakawa Chemical Industries, Ltd.) as a water repellent. A coated paper was obtained in the same manner as in Example 1 except that 2 parts by mass was added.

Example 4
In Example 2, the zirconium carbonate ammonium salt (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) of the coating solution for the inner coating layer and the coating solution for the outermost coating layer was increased to 3 parts by mass, and the water repellent A coated paper was obtained in the same manner as in Example 2 except that 2 parts by mass of styrene-acrylic resin (trade name; Polymaron 1308, manufactured by Arakawa Chemical Industries, Ltd.) was added.

Example 5
In Example 1, zirconium carbonate ammonium salt (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) was increased to 3 parts by mass, and modified amine-based resin (trade name: Sumire Resin SPI-102A, Sumika Chemtech Co., Ltd.) was used as a gas permeability improvement aid. Coated paper was obtained in the same manner as in Example 1 except that 1 part by mass) was added.

Example 6
In Example 2, the zirconium carbonate ammonium salt (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) of the inner coating layer coating solution and the outermost coating layer coating solution was increased to 3 parts by mass to improve air permeability. A coated paper was obtained in the same manner as in Example 2 except that 1 part by mass of polyamide resin (trade name: Sumire Resin 633, manufactured by Sumika Chemtech Co., Ltd.) was added as an agent.

Example 7
In Example 2, the coated paper was prepared in the same manner as in Example 2 except that no zirconium carbonate ammonium salt (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) was added to the inner coating layer coating solution. Obtained.

Comparative Example 1
A coated paper was obtained in the same manner as in Example 1, except that zirconium ammonium carbonate (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) was not added.

Comparative Example 2
In Example 2, except that neither zirconium carbonate ammonium salt (trade name; Baycoat 20, manufactured by Nippon Light Metal Co., Ltd.) was added to the inner coating layer coating solution or the outermost coating layer coating solution. Coated paper was obtained in the same manner as Example 2.

The coated paper obtained in Examples 1 to 7 and Comparative Examples 1 and 2, as well as the off-wheel printed material and the color copy printed material were evaluated by the following evaluation methods.
[Number of coating layer surface cracks]
The surface of the coated paper was observed with an electron microscope at a magnification of 100 times or 500 times to examine the number of cracks existing at 100 mm ^2, and the number of cracks per 1 mm ² was calculated.

[Evaluation of blank paper glossiness]
Based on JIS Z 8741, the glossiness of white paper was measured under the conditions of an incident angle and a light receiving angle of 75 degrees. For the measurement, GLOSS METER MODEL GM-26D manufactured by Murakami Color Research Laboratory was used.

[Evaluation of air permeability]
JAPAN TAPPI Paper Pulp Test Method No. Based on 5-2: 2000, the air permeability of the paper was measured using a fully automatic digital type Oken air permeability and smoothness tester EYO manufactured by Asahi Seiko Co., Ltd. It represents that it has air permeability, so that an air permeability numerical value (second) is small.

[Printing coated paper]
[Off-wheel printing]
Using an offset rotary printing press (Mitsubishi Risopia L-BT3-1100 / Mitsubishi Heavy Industries), both sides are 4 color solid design, printing speed is 600 rpm, paper temperature at the dryer outlet is 120 ° C, and cooling after passing through the dryer The roll was folded continuously with printing through cooling water at 10 ° C.

[Evaluation of blanket dirt]
As the evaluation of water resistance, after the above-mentioned off-wheel printing, the stain state of the printing blanket was visually determined and evaluated in five stages of 1 to 5.
5: A level in which no dirt is observed on the blanket and it is extremely excellent.
4: Stain is hardly observed on the blanket, and is an excellent level.
3: A small amount of peeling of the coating layer is observed on the blanket, but at a level that is not a problem in practice.
2: A large amount of peeling of the coating layer on the blanket was observed, and there was a problem in practical use.
1: Peeling of the coating layer on the blanket was remarkably observed, and there was a problem in practical use.

[Evaluation of off-wheel blister]
The blister generation state of the off-wheel printed material was visually judged and evaluated in 5 stages of 1 to 5.
5: A blister is not observed at all and is a very excellent level.
4: The blister is hardly observed and is an excellent level.
3: A small amount of fine blisters are observed, but there is no practical problem.
2: A level in which a large amount of fine blisters are observed and there is a practical problem.
1: A large amount of large blisters is observed, and there is a problem in practical use.

[Evaluation of color copy blister]
Using a color copying machine IPSiO Color 2100 manufactured by RICOH, 100 continuous color prints were made on A4 size coated paper, and the blister generation status was visually judged and evaluated in 5 stages from 1 to 5.
5: A blister is not observed at all and is a very excellent level.
4: The blister is hardly observed and is an excellent level.
3: A small amount of fine blisters are observed, but there is no practical problem.
2: A level in which a large amount of fine blisters are observed and there is a practical problem.
1: A large amount of large blisters is observed, and there is a problem in practical use.

[Evaluation of print finish]
The printed finished state of the above-mentioned off-wheel printed matter was visually judged and evaluated in 5 stages from 1 to 5.
5: Extremely excellent level.
4: Level that is quite excellent.
3: Slightly inferior, but practically no problem.
2: Level that is considerably inferior and problematic in practical use.
1: Significantly inferior and practically problematic level.

[Evaluation of off-wheel wrinkles]
The off-wheel wrinkle occurrence state of the double-sided, four-color solid printing part was visually determined and evaluated in five stages of 1 to 5.
5: Very good level with no wrinkles observed.
4: The generation | occurrence | production of wrinkles is hardly recognized and it is the level which is excellent.
3: Occurrence of mild wrinkles is recognized, but there is no practical problem.
2: Occurrence of wrinkles was observed and there was a problem in practical use.
1: A level where there is a problem in practical use because of severe wrinkles.

[Evaluation of fracture resistance]
The printed coated paper is cut into A4 size, folded in half with a paper folding machine (made by Horizon) in an environment of temperature 23 ° C. and humidity 50% RH, and the bent part is observed with an enlarged loupe. , 1 to 5 were evaluated.
5: The coating layer at the bent portion has no cracks or tears and is good.
4: The coating layer at the bent portion has almost no cracks or tears and has no practical problem.
3: Some cracks are observed in the coating layer at the bent portion, but there is no practical problem.
2: Cracks and tears are seen in the coating layer at the bent part, which is problematic in practice.
1: Cracks and tears are observed in the coating layer at the bent part, and the pulp fibers of the paper substrate are exposed, which is extremely inferior.

  The above evaluation results are shown in Table 1.

As described above in detail, the coated paper according to the present invention is excellent in air permeability and water resistance, does not generate blisters, and has a good print finish during off-wheel printing and electrophotographic printing. In addition, off-wheel wrinkles do not occur and no cracking occurs, which is extremely useful in practice.

Claims (7)

In a coated paper having a sheet-like paper base material and at least one coating layer formed on at least one surface thereof and containing a pigment and an adhesive as main components, the pigment has an average particle size Kaolin particles having a diameter of 0.1 to 1.5 μm and satisfying the following formula (1):
5 ≦ L / W ≦ 50 (1)
[In the formula (1), L represents the major axis of the kaolin particles, and W represents the minor axis of the kaolin particles.]
The adhesive is selected from (a) a copolymer having a glass transition temperature of 10 to 60 ° C. and having a single structure, and (b) a synthetic polymer compound having a core-shell structure. The coated paper further comprises at least one selected from a zirconium compound, a polyamide resin, and an amine resin in the coating layer. The coating layer is at least two layers, and in the inner coating layer adjacent to the sheet-like paper substrate, any one of a needle-like crystal, a spindle-like crystal, a columnar crystal, and a rice granular crystal In the outermost coating layer containing a pigment having a structure and formed on the inner coating layer, the pigment has an average particle diameter of 0.1 to 1.5 μm, and the following formula (1 ) Kaolin particles satisfying:
5 ≦ L / W ≦ 50 (1)
[In the formula (1), L represents the major axis of the kaolin particles, and W represents the minor axis of the kaolin particles.]
The adhesive is selected from (a) a copolymer having a glass transition temperature of 10 to 60 ° C. and having a single structure, and (b) a synthetic polymer compound having a core-shell structure. Furthermore, the coated paper of Claim 1 containing at least 1 sort (s). The coated paper according to claim 2, wherein the outermost coating layer contains thermoplastic organic fine particles having a glass transition temperature of 20 to 150C. The glass transition temperature of the synthetic polymer compound (b) having the core-shell structure is represented by the following formulas (2) and (3):
Tg1 <Tg2 (2)
−10 ° C. <Tg2 <100 ° C. (3)
[In the formulas (2) and (3), Tg1 represents the glass transition temperature of the core portion in the synthetic polymer compound (b) having a core-shell structure, and Tg2 represents the glass transition temperature of the shell portion. The coated paper according to claim 1 or claim 2, satisfying The coated paper according to claim 1, wherein at least one selected from a zirconium compound, a polyamide resin, and an amine resin is contained in 100 parts by mass of the coating layer in an amount of 0.01 to 10 parts by mass. The coated paper according to claim 1, wherein the surface of the coated paper has a glossiness of 45% or more. The coated paper according to claim 1, wherein the air permeability of the coated paper is 7000 seconds or less.