JP2000226791A - Coated paper - Google Patents

Abstract

(57) [Summary] [Problem] To achieve high glossiness of blank paper, excellent ink receptivity in offset printing, no blistering,
Provide a coated paper from which a high-quality image can be obtained. SOLUTION: A paper base material and a coating layer mainly composed of a pigment and an adhesive are provided on both surfaces thereof, and 100 parts by weight of the pigment in the coating layer have an aspect ratio of 5 to 15, The coated paper contains 60 parts by weight or more of kaolin having an average particle diameter of 0.3 to 1.0 μm, and the coated paper has a white paper glossiness of 50 on the surface of the coating layer.
~ 80%, air permeability of 7000 seconds or less; TAPP
I No. 0.27 internal bond strength according to 54-93
０．８0.85 KJ / m ² . Further, in 100 parts by weight of the pigment, an average particle size of 0.5
It is preferable to include 1 to 10 parts by weight of a hollow organic pigment having a size of 1.5 μm. Further, the paper base material preferably has a Beck smoothness of 50 seconds or less and an air permeability of 40 seconds or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated paper which is excellent in the receptivity of a printing ink, in particular, has high gloss of a white paper and does not generate blisters.

[0002]

2. Description of the Related Art In a printing paper used for offset printing, an art in which a coating layer mainly composed of a pigment and an adhesive is provided on a paper base in order to satisfy a finished print after printing is obtained. Coated paper such as paper and coated paper is used. Such a coated paper has a low glossiness to a mat (glossiness of 20% or less), dull (glossiness 2
0-45%) and gloss (gloss 45% or more). In particular, gloss with high glossiness of white paper is subjected to super calendering after coating the coating layer, so that the density of the base paper and the coating layer increases, and the air permeability (in general coated paper, the air permeability is about 15,000 seconds) ) Is markedly reduced. However, in the rotary printing method in which the drying of the ink is instantaneously performed by the high heat of an oven or the like, when a gloss-type coated paper is used, the image portion swells (hereinafter, referred to as a blister) when the ink is dried, so that the appearance is reduced. Therefore, an improvement is desired because of a significant decrease in the value.

[0003] Blisters are used for heat treatment of ink.
(1) When the water vapor in the coated paper expands, the paper base layer is broken and large blisters, that is, macro blisters are generated in the image area. (2) The water vapor between the ink and the coating layer expands. In some cases, fine blisters, that is, micro blisters are generated in the image portion.

[0004] As a general countermeasure, for the macro blister, a method of increasing the internal bonding strength of the paper base to prevent the paper base layer from bursting, and for the micro blister, improving the air permeability of the coating layer are considered. Can be Regarding macro blisters, Japanese Patent Application Laid-Open No. Hei 3-227491 proposes a method of adding a polyacrylamide-based paper-strengthening agent. However, when the amount of addition is increased, floc is generated. The amount of addition is limited in terms of formation,
Even if a coating layer is provided using the obtained paper substrate, the blister has not been sufficiently improved. Regarding micro blisters, Japanese Patent Application Laid-Open No. 4-241199 proposes an attempt to increase the porosity of the undercoat layer by cationizing the undercoat layer and improve the air permeability, but sufficient air permeability is obtained. Therefore, micro-blisters cannot be completely suppressed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-described problems, and it is intended to improve the glossiness of blank paper and the ink receptivity in offset printing. An object of the present invention is to provide a coated paper from which high quality images can be obtained without generation.

[0006]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies on the relationship between the internal bond strength of a paper substrate and the air permeability of a coating layer, and on the occurrence of blisters. In a coated paper in which a coating layer mainly composed of a pigment and an adhesive is provided on both sides of a paper base material, kaolin having a specific range of an aspect ratio and an average particle size, which are a ratio of a plane major axis to a thickness, is mainly used. The coating liquid as a pigment was coated, dried and smoothed, and the coated paper obtained was found to have air permeability and a specific range of internal bond strength. The invention has been completed.

That is, the coated paper according to the present invention comprises a paper base material and, on both sides thereof, a coating layer mainly composed of a pigment and an adhesive, and 100 parts by weight of the pigment in the coating layer. inside,
Aspect ratio 5-15, average particle size 0.3-1.0 μm
Containing at least 60 parts by weight of kaolin, and of the coated paper,
The glossiness of blank paper on the surface of the coating layer is 50 to 80%, and the air permeability is 70.
00 seconds or less; TAPPI No. Internal bond strength analogous to 54-93 is characterized in that a 0.27~0.85KJ / m ^2.

It is preferable that 100 parts by weight of the pigment contains 1 to 10 parts by weight of a hollow organic pigment having an average particle size of 0.5 to 1.5 μm. Further, the paper base material preferably has a Beck smoothness of 50 seconds or less and an air permeability of 40 seconds or less.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have proposed that high gloss and low air permeability can be imparted to coated paper while maintaining a high gloss while maintaining a coated layer in a bulky structure by a light smoothing treatment. As a result of intensive studies, it is necessary to obtain kaolin having an aspect ratio in the range of 5 to 15 and an average particle diameter of 0.3 to 1.0 μm as the main pigment of the coating layer. As a result, it has been found that high gloss and high air permeability can be obtained, and coated paper free of generation of macro blisters and micro blisters has been obtained.

[0010] Generally used aspect ratio of 15 to
Compared to kaolin 20 or delaminated kaolin having an aspect ratio of 40 or more, the kaolin used in the present invention has an aspect ratio in the range of 5 to 15, has a large thickness, and has an average particle diameter of 0.3 to 0.3. Since it is a small hexagonal plate with a small particle size of 1.0 μm and a uniform particle size distribution, the gap between the pigments does not become a dense structure after the coating layer is smoothed, and it is a characteristic of hexagonal plate-shaped kaolin. It is presumed that this is because it has high flatness.

When the particle size is smaller than 0.3 μm, gloss tends to be obtained, but air permeability is significantly reduced.
On the other hand, if it is larger than 1.0 μm, it becomes difficult to obtain gloss, and a desired gloss cannot be obtained. Regarding the particle size distribution, it is preferable that the particle size distribution with a particle size of 0.25 to 1.0 μm is 65% or more.

Kaolin used as the main pigment of the present invention is
60 parts by weight to 1 part by weight based on 100 parts by weight of all pigments in the coating layer
It is blended in the range of 00 parts by weight. By the way, if it is less than 60 parts by weight, the air permeability is significantly reduced.

Further, the present inventors have conducted intensive studies on suppressing the generation of macro blisters. T
APPI No. It has been found that by adjusting the internal bond strength according to No. 54-93 to 0.27 to 0.85 KJ / m ² , it is possible to prevent macro blisters generated by bursting between layers of the paper substrate. Incidentally, when the internal bond strength is less than 0.27 KJ / m ² , the generation of macro blisters cannot be completely prevented even if the air permeability of the coated paper is increased. On the other hand, when it exceeds 0.85 KJ / m ² , pulp flocs are generated, and the formation and appearance are significantly reduced. Preferably, a 0.35~0.85KJ / m ^2.

To improve the internal bond strength of the paper substrate,
For example, there are types of pulp such as those manufactured from high-rigidity softwood, improving the inter-fiber bonding by advancing beating, addition of a paper strength enhancer, resin impregnation, coating, etc., but depending on the purpose, Selected.

The paper substrate of the present invention preferably has a Beck smoothness of 50 seconds or less and an air permeability of 40 seconds or less. If the Bekk smoothness exceeds 50 seconds, operability may be reduced, such as occurrence of streaks and poor adhesion of paint.
On the other hand, if the air permeability exceeds 40 seconds, the air permeability after providing the coating layer and performing the smoothing treatment becomes poor, and the generation of blisters cannot be completely prevented. Preferably, the Beck smoothness is 30
Seconds or less, air permeability is 30 seconds or less.

The Beck smoothness of the paper substrate is adjusted using a smoothing device such as a machine calender or a soft nip calender. On the other hand, the adjustment of the air permeability is made of a paper-strength enhancer such as polyamide, acrylamide, amine compound, amide, epoxy or melamine compound, natural wax,
Olefin-based, zirconium-based or fluorine-based wax water repellent, and polyvinyl alcohol, fluorine-based resin, acrylic resin, styrene-based resin, acryl-styrene-based copolymer resin, amide-based resin, urethane-based resin,
It is performed by a process such as impregnation with a water-soluble resin such as an epoxy resin or a water-dispersible resin, and size press coating.

In the present invention, the coating layer has an average particle size of 0.5
To 1.5 μm hollow organic pigment,
It is also possible to mix up to 10 parts by weight.

The present inventors have conducted intensive studies on improving the receptivity of the printing ink. As a result, 100% by weight of the hollow organic pigment having an average particle diameter of 0.5 to 1.5 μm was added to the coating layer. It was found that the addition of 1 to 10 parts by weight with respect to parts improved the acceptability of the printing ink, and the present invention was completed. About this phenomenon, it is not clear, but by mixing a soft, high cushioning hollow organic pigment in the coating layer, the cushioning property of the coating layer surface has been improved, and the hollow organic pigment and ink Is presumed to have good affinity.

If the average particle size of the hollow organic pigment is less than 0.5 μm, the air permeability of the coating layer may be reduced. On the other hand, if the average particle size is larger than 1.5 μm, desired gloss may not be obtained. When the amount exceeds 10 parts by weight, operability such as streak may be remarkably reduced. When the amount of the hollow organic pigment is 1
If the amount is more than 0 parts by weight, the strength of the coating layer is reduced, and the blanket may be stained during printing. A more preferred amount is 1 to 4 parts by weight.

The hollow organic pigment used in the present invention may be a polystyrene resin, a styrene-acrylic copolymer resin,
Urea resin, melamine resin, acrylic resin, vinylidene chloride resin, benzoguanamine resin,
One or more of these are appropriately selected and used.

The pulp of the paper substrate is not particularly limited with respect to the production method and the kind, etc., and chemical pulp such as KP, mechanical pulp such as SGP, RGP, BCTMP and CTMP, and used paper such as deinked pulp Pulp, non-wood pulp such as kefna, bamboo, straw, hemp, and the like, organic synthetic fibers such as polyamide fiber, polyester fiber, and polynosic fiber, and inorganic fibers such as glass fiber, ceramic fiber, and carbon fiber can also be used.

A filler can be added to the paper substrate as needed. The filler in this case is not particularly limited, but various pigments generally used for high quality paper,
For example, mineral pigments such as kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, magnesium carbonate, magnesium oxide, silica, white carbon, bentonite, zeolite, sericite, smectite and the like. And organic pigments such as polystyrene resins, urea resins, melamine resins, acrylic resins, vinylidene chloride resins, and fine hollow particles thereof.

In the paper stock, besides pulp fiber and filler,
Various anionic, nonionic, cationic or amphoteric retention improvers, drainage improvers, paper-strength enhancers and internal sizing agents that have been conventionally used within the range not impairing the desired effects of the present invention. And the like can be appropriately selected and used as needed. Furthermore, dyes, optical brighteners, pH adjusters, defoamers, pitch control agents,
An internal additive for papermaking, such as a slime control agent, can also be appropriately added according to the use of the paper.

The papermaking method is not particularly limited, and examples thereof include an acidic papermaking method having a papermaking pH of about 4.5,
It can be applied to all papermaking methods, including alkaline filler such as calcium carbonate as a main component, from weakly acidic papermaking pH of about 6 to weakly alkaline neutral papermaking method of papermaking pH of about 9, and the paper machine is also Fourdrinier papermaking. Machine, twin wire paper machine, round mesh paper machine, Yankee paper machine can be used as appropriate.

As the pigment used in the coated paper of the present invention, in addition to the kaolin of the present invention and the hollow organic pigment, for example, heavy calcium carbonate, light calcium carbonate, kaolin, calcined kaolin, structural kaolin, delamikaolin, talc,
Calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, alumina, magnesium carbonate, magnesium oxide,
Mineral pigments such as silica, magnesium aluminosilicate, finely divided calcium silicate, finely divided magnesium carbonate, finely divided light calcium carbonate, white carbon, bentonite, zeolite, sericite, smectite, polystyrene resin, styrene-acrylic copolymer Organic pigments such as resin, urea resin, melamine resin, acrylic resin, vinylidene chloride resin, benzoguanamine resin and the like, and organic pigments such as through-hole resin can be used. Alternatively, two or more kinds are appropriately selected and used.

As the adhesive, a water-soluble and / or water-dispersible polymer compound can be used. For example, cationic starch, amphoteric starch, oxidized starch, enzyme-modified starch, thermochemically modified starch, esterified starch , Starches such as etherified starch, carboxymethyl cellulose, cellulose derivatives such as hydroxyethyl cellulose, gelatin, casein,
Natural or semi-synthetic polymer compounds such as soy protein, natural rubber, etc .; polydienes such as polyvinyl alcohol, isoprene, neoprene (registered trademark) and polybutadiene; polyalkenes such as polybutene, polyisobutylene, polypropylene and polyethylene; vinyl halide; vinyl acetate Vinyl polymers and copolymers such as styrene, styrene, (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylamide, and methyl vinyl ether; and synthetic rubber latex such as styrene-butadiene and methyl methacrylate-butadiene. And synthetic polymers such as polyurethane resins, polyester resins, polyamide resins, olefin-maleic anhydride resins, and melamine resins. One or more of these may be appropriately selected and used depending on the purpose.

The mixing ratio of the adhesive is in the range of 5 to 50 parts by weight (solid part) based on 100 parts by weight (solid part) of the pigment. If the amount is less than 5 parts by weight, the strength of the coating film of the coating layer is weak, and the coating layer may peel off and accumulate on the printing plate of a rotary press, which may cause damage to the printing plate. On the other hand, this is 5
If the amount exceeds 0 parts by weight, the coating layer becomes dense and the air permeability may be significantly reduced.

In the coating liquid, in addition to these pigments and adhesives, various auxiliaries such as surfactants, pH adjusters, viscosity adjusters, softeners, gloss imparting agents, waxes, dispersants, fluidizers Denaturing agents, antistatic agents, stabilizers, antistatic agents, crosslinking agents,
A sizing agent, a fluorescent whitening agent, a coloring agent, an ultraviolet absorber, an antifoaming agent, a waterproofing agent, a plasticizer, a lubricant, a preservative, a fragrance, and the like can be appropriately used as needed.

The coating amount of the coating layer of the present invention is 8 to 20 g /
m ² , preferably 10 to ²⁰ g / m ² is required. If the coating amount is less than 8 g / m ² , it is not possible to sufficiently cover the irregularities on the surface of the paper substrate, so that the acceptability of the printing ink may be significantly reduced. On the other hand, if it exceeds 20 g / m ² , operability such as poor drying property during coating is reduced, and the production cost is increased.

As a coating method for forming a coating layer, generally known coating apparatuses such as a blade coater, an air knife coater, a roll coater, a reverse roll coater, a bar coater, a curtain coater, a die slot coater, a gravure coater, and a chanter Apparatuses such as a plex coater, a brush coater, a two-roll or metering blade type size press coater, a bill blade coater, a short dwell coater, and a gate roll coater are appropriately used.

The coating layer is formed on both sides of the paper substrate, and if necessary, one layer or two or more intermediate layers may be provided to form a multilayer structure. In the case of a double-sided coating or a multilayer structure, each coating liquid does not need to have the same or the same coating amount, and may be appropriately adjusted and blended according to a required quality level, and is particularly limited. is not. When a coating layer is provided on one side of the paper substrate, a coating layer made of a synthetic resin layer, a pigment and an adhesive, or an antistatic layer is provided on the back side to prevent curling, impart printability, and supply and discharge paper. It is also possible to give the like. Further, the back surface of the paper substrate may be subjected to various processes, for example, post-processes such as adhesion, magnetism, flame retardancy, heat resistance, water resistance, oil resistance, and anti-slipping, so that it is possible to use the paper substrate with additional applicability.

According to the present invention, after providing a coating layer on a paper substrate,
It is smoothed in a normal drying process or surface treatment process, etc.
It is finished by adjusting the water content to be about 3 to 10%, preferably about 4 to 8%.

The smoothing process is performed by a normal smoothing device such as a super calender, a gloss calender, a soft calender, etc., and is used as appropriate in an on-machine or an off-machine. The number of pressure nips, heating, and the like are also appropriately adjusted according to a normal smoothing treatment device.

Since the coated paper subjected to the smoothing treatment needs to have the texture of the printing paper, it is required to conform to JIS Z87.
The glossiness of blank paper at 75 degrees of incidence / receiving angle based on 41 is 50 ~
It is preferably 80%, more preferably 60 to 80%. Further, the air permeability is preferably adjusted to 7000 seconds or less, more preferably 5000 seconds or less, and still more preferably 3000 seconds or less.

If the glossiness is less than 50%, the appearance of a white paper and the desired glossiness may not be obtained. On the other hand, if the glossiness is higher than 80%, even if the pigment used in the present invention is used, the transparency will not increase. The temper cannot be adjusted to 7000 seconds or less, and macro blisters or micro blisters may occur. By the way, if the air permeability exceeds 7000 seconds, micro blisters may be generated even if the internal bond strength of the coated paper is 0.27 to 0.85 KJ / m ² . On the other hand, when the internal bonding strength is less than 0.27 KJ / m ² even when the air permeability is 5000 seconds or less, macro blisters may be generated.

The coated paper obtained by the above method is
It can be used as a non-impact printing type image recording paper such as an electrophotographic type or a thermal transfer type because of its surface smoothness and high air permeability as well as its offset rotary printing suitability.

[0037]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples, but it is needless to say that the present invention is not limited to these ranges. In the examples, “parts” and “%” indicate “parts by weight (solid content)” and “% by weight” unless otherwise specified.

Example 1 [Preparation of base material] LBKP (freeness (CSF) = 50
0ml) 70 parts, NBKP (freeness (CSF) = 5
(00ml) 30 parts of pulp slurry, 0.1% of polyacrylamide resin (trade name: PS117, manufactured by Arakawa Chemical Industries) as a paper strength enhancer and polyacrylamide resin (trade name: PS460, Arakawa Chemical Co., Ltd.) 0.3)
% And one part of a sulfuric acid band, and the mixture was diluted with white water to prepare a stock having a pH of 5.3 and a solid content of 1.1%. The stock is made using a Fourdrinier machine,
Polyacrylamide resin (trade name; Polymer Set 53)
1, Arakawa Chemical Industry Co., Ltd.) with a size press of 2%, applied by a size press so that the applied amount becomes 1 g / m ^{2 in} dry weight, dried and Beck smoothness by machine calender Smooth processing to 30 seconds to obtain a basis weight of 8
A base paper of 0 g / m ² was obtained (paper base). Table 1 shows the Beck smoothness, air permeability, and internal bond strength of the paper substrate.

[Preparation and Coating of Coating Liquid] 100 parts of Astra Plus (component: Kaolin, manufactured by Huber Corporation) was used as a dispersant with sodium polyacrylate (trade name: Alon A-
9, manufactured by Toa Gosei Co., Ltd.), and dispersed in water using a CORES disperser to prepare a pigment slurry. 3.0 parts of oxidized starch (trade name; Ace A, manufactured by Oji Cornstarch Co., Ltd.) and 10 parts of styrene butadiene copolymer latex (trade name: OX1060, manufactured by Zeon Corporation) are added to the pigment slurry, and the mixture is stirred. Water was added to prepare a coating liquid having a solid content of 50%. Table 2 shows the composition, shape, aspect ratio, average particle size, and particle size distribution of the inorganic pigments used.

[Formation of Coating Layer on Paper Substrate] The obtained coating liquid was dried at a dry weight of 12 g / m ² per one side of the paper substrate.
Using a blade coater, both sides are coated using a blade coater, and the paper is passed through a pressure nip composed of a metal roll and an elastic roll, and the glossiness of the white paper at an incident / receiving angle of 75 degrees according to JIS Z8741 is 65%. So that the basis weight is 10
4 g / m ² of coated paper was obtained.

Example 2 Astraplus used in Example 1 (components: kaolin,
A coated paper was prepared and evaluated in the same manner, except that 100 parts of Huber Co.) was changed to 70 parts of Astra Plus and 30 parts of Brilliant (component: light calcium carbonate, manufactured by Shiraishi Calcium Co.).

Comparative Example 1 Astraplus used in Example 1 (components: kaolin,
A coated paper was prepared and evaluated in the same manner except that 100 parts of HUBER Co., Ltd. was changed to 50 parts of Astra Plus and 50 parts of brilliant (component: light calcium carbonate, manufactured by Shiraishi Calcium Co., Ltd.).

Comparative Examples 2 to 4 Astraplus used in Example 1 (components: kaolin,
100 parts of Huber), chao gloss (component; kaolin, manufactured by Huber) (Comparative Example 2), astraplate (component: Delamikaolin, manufactured by Huber) (Comparative Example 3), brilliant (component: light calcium carbonate, A coated paper was prepared and evaluated in the same manner except that the composition was changed to Shiraishi Calcium Co. (Comparative Example 4). Here, in Comparative Examples 3 and 4, the calendering conditions were enhanced, but the glossiness did not increase.

Examples 3 to 5 Astraplus used in Example 1 (components: kaolin,
100 parts of Astra Plus (Huber).
97.5 parts of Kaolin, manufactured by Huber and HP91 (component: hollow organic pigment, manufactured by Rohm & Haas) 2.5 parts (Example 3), 95 parts of Astra Plus (component; kaolin, manufactured by Huber) and 95 parts of HP91 (Component: hollow organic pigment, manufactured by Rohm & Haas) 5 parts (Example 4), 90 parts of Astra Plus (component: kaolin, manufactured by Huber) and HP91
(Component: hollow organic pigment, manufactured by Rohm & Haas Co., Ltd.) A coated paper was prepared and evaluated in the same manner except that the amount was changed to 10 parts (Example 5).

Comparative Example 5 Astraplus used in Example 1 (components: kaolin,
100 parts of Astra Plus (Huber).
Coated papers were prepared and evaluated in the same manner except that 50 parts of kaolin (manufactured by Huber) and 50 parts of chao gloss (component: kaolin, manufactured by Huber) were changed.

Examples 6 to 7 The same procedures as in Example 4 were carried out except that the coating amount was changed to 8 g / m ² (absolute dry solids) (Example 6) and 18 g / m ² (Example 7). Paper was made and evaluated.

Comparative Example 6 A coated paper was prepared and evaluated in the same manner as in Example 4, except that the coating amount was changed to 6 g / m ² (absolute dry solid content).

Examples 8 to 9 Coated papers were prepared in the same manner as in Example 4 except that the glossiness after the smoothing treatment was changed to 55% (Example 8) and 75% (Example 9). evaluated.

Example 10 In preparing the paper substrate of Example 4, the amount of polyacrylamide-based resin (trade name; PS117, manufactured by Arakawa Chemical Industry Co., Ltd.) was 0.4%, and the amount of polyacrylamide-based resin (trade name) was changed. ; PS
460, manufactured by Arakawa Chemical Industries Co., Ltd.), except that the amount of addition (paper base) was changed to 0.6%, and a coated paper was prepared and evaluated in the same manner.

Comparative Example 7 A coated paper was prepared and evaluated in the same manner as in Example 4, except that the polyacrylamide-based resin was not added, and the size press was changed to water (paper base). .

Comparative Example 8 In the preparation of the paper substrate of Example 4, the addition amount of polyacrylamide resin (trade name; PS117, manufactured by Arakawa Chemical Industry Co., Ltd.) was 0.7%, and polyacrylamide resin (trade name; PS
460 (Arakawa Chemical Industry Co., Ltd.), except that the amount of addition was changed to 0.8% (paper base).

Evaluation Method [Measurement of Average Particle Diameter and Particle Size Distribution of Pigment] A Sedigraph 5100 V3.07 was used as a measuring instrument. Table 2 shows the results.

[Measurement of Aspect Ratio of Pigment and Observation of Shape]
The image was magnified 15,000 times with an electron microscope to measure the aspect ratio and observe the shape. Table 2 shows the results.

[Measurement of Internal Bonding Strength of Paper Substrate and Coated Paper] TAPPI No. It measured according to 54-93. The measuring instrument used was an internal bond tester Model-B manufactured by SCOTT.

[Measurement of Air Permeability of Paper Substrate and Coated Paper] The air permeability was measured by an Oken type air permeability meter.

[Measurement of Beck Smoothness of Paper Base] Measured by a Beck smoothness measuring device.

[Measurement of Glossiness of Coated Paper] The glossiness was measured under the conditions that the incident angle and the light receiving angle were 75 degrees. The measuring instrument is GLOSS METER MODEL G manufactured by Murakami Color Research Laboratory.
M-26D was used.

[Printing of Coated Paper] A printing machine was used under the following conditions, using Komori System C-20 manufactured by Komori Corporation Environment: 20 ° C., 65% RH Printing speed: 200 to 250 m / min Printing length: 6000m Drying conditions: Adjust the paper surface temperature to 150 ° C using a gas heater

(Evaluation of Printing Ink Acceptability of Coated Paper) Evaluation was made according to the following evaluation criteria. ：: No missing or missing dot. There is no problem in practical use,
The quality is also excellent. ：: Missing or missing dots are slightly observed. No problem in practical use. Δ: Missing or missing dots are frequently observed. There is a practical problem. ×: Dropouts and chipping of dots are remarkably observed. There is a problem in practical use, and the quality is extremely poor.

(Evaluation of Stain on Blanket) Stain on the blanket after printing at 6000 m was evaluated according to the following evaluation criteria. A: No stain is observed. There is no practical problem and the quality is excellent. ：: Dirt is slightly observed. No problem in practical use. Δ: Dirt is frequently observed. There is a practical problem. X: Stain was remarkably observed. There is a problem in practical use, and the quality is extremely poor.

(Evaluation of Macro Blister) The state of occurrence of macro blisters was confirmed with a magnifying loupe (30 times) and evaluated according to the following evaluation criteria. ：: Macro blister was not observed. There is no practical problem and the quality is excellent. ：: Macro blister is slightly observed. No problem in practical use. Δ: Macro blisters are frequently observed. There is a practical problem. X: Macro blister was remarkably observed. There is a problem in practical use, and the quality is extremely poor.

(Evaluation of Micro Blister) The state of occurrence of micro blisters was confirmed with a magnifying loupe (30 times) and evaluated according to the following evaluation criteria. ：: Micro blister was not observed. There is no practical problem and the quality is excellent. ：: Micro blisters are slightly observed. No problem in practical use. Δ: Micro blisters are frequently observed. There is a practical problem. X: Micro blisters were remarkably observed. There is a problem in practical use, and the quality is extremely poor.

[Evaluation of Paper Substrate and Coated Paper]
Tables 1 and 3 show the results of the air permeability, glossiness and internal bond strength of the paper substrate and the obtained coated paper. The printing paper was evaluated for acceptability of printing ink, contamination of blanket and blister. The results are shown in Table 4.

[0064]

[Table 1]

[0065]

[Table 2]

[0066]

[Table 3]

[0067]

[Table 4]

[0068]

EFFECT OF THE INVENTION The coated paper according to the present invention is a coated paper that has high glossiness of white paper, is excellent in ink receptivity in offset printing, has no blistering, and can obtain high-quality images. It is extremely useful in practice.

Claims (3)

[Claims] 1. A coated paper comprising a paper base material and a coating layer mainly composed of a pigment and an adhesive provided on both surfaces thereof, wherein 100 parts by weight of the pigment in the coating layer have an aspect ratio of Ratio 5
15, kaolin having an average particle size of 0.3 to 1.0 μm is mixed with 60
The coated paper has a white paper glossiness of 50 to 80%, an air permeability of 7000 seconds or less, and J.I. TAPPI No. Coated paper, wherein the internal bond strength is 0.27~0.85KJ / m ² analogous to 54-93. 2. The coated paper according to claim 1, wherein 100 parts by weight of the pigment contains 1 to 10 parts by weight of a hollow organic pigment having an average particle size of 0.5 to 1.5 μm. 3. The coated paper according to claim 1, wherein the paper base material has a Beck smoothness of 50 seconds or less and an air permeability of 40 seconds or less.