JP2003013392A - Coated paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated paper that has high white paper glossiness and excellent paper-running properties on a printing machine and resists to the occurrence of offset or blocking on the back face, after printing in the offset sheet feed printing. SOLUTION: The coated paper comprises the paper base and at least one of the coated layer mainly comprising pigment and adhesive on the base paper in which the surface of the coating layer characteristically has 10-1,000 convexes/mm<2> and the white paper glossiness is 45-58%. In a preferred embodiment, spherical particles of 3.0-50.0 μm average particle size is included in the coated layer and additionally preferred that the base paper is coated from the outside with the spherical particles of 3.0-50.0 μm average particle size thereby having 10-1,000 convexes/mm<2> . Further, the static friction coefficient preferably is 0.2-0.7 on the surface of the coated layer.

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 has a high gloss of white paper, is particularly excellent in show-through of printing ink and paper runnability, and has good operability.

[0002]

2. Description of the Related Art Offset printing is divided into a rotary printing method and a sheet-fed printing method according to the form of paper used. In the rotary printing method, roll paper is used for continuous printing, and printing ink is wound up after a drying process. Or cut appropriately and stocked. On the other hand, in the sheet-fed system, the sheets are fed one by one, and after printing, there is no drying process, and the printed sheets are stacked and stocked. In this case, the show-through of the printing ink is likely to occur. Therefore, in the sheet-fed method, air is blown between the papers at the paper feed section to suppress the adhesion between the papers, and at the stack section, powder or the like is put between the papers to prevent show-through or blocking of the paper after printing. Preventing outbreak.

The occurrence of double feeding in the paper feeding section has been improved by the blowing of air, but it is not yet sufficient. On the other hand, the powder in the stacker portion has the effect of preventing show-through and blocking, but the powder remains on the printing surface, so this powder causes printing problems during back-side printing or additional printing. Usually, the adhesion efficiency of the powder to the printed surface is 20 to 30%, and the rest is scattered in the air, and it is desired to reduce the powder as much as possible in order to deteriorate the working environment and protect the machine. For this reason, ultraviolet curing or the like is performed using ultraviolet curable ink, but a printing paper without ink show-through is desired.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and has a high glossiness of a blank sheet, an excellent sheet running property in a printing machine, and an offset sheet-fed sheet. The object of the present invention is to provide a coated paper in which show-through and blocking are less likely to occur on the back surface of the paper after printing and a high-quality image is obtained.

[0005]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present inventors have earnestly studied the surface property of a coating layer and show-through or blocking on the back surface of paper, and as a result, both surfaces of a paper substrate have been investigated. In a coated paper in which a coating layer containing a pigment and an adhesive as a main component is provided, a base paper coated with spherical particles is coated with a coating liquid containing kaolin as a main pigment, and / or Spherical particles are contained in the coating liquid as a pigment to apply the coating, and after drying, smoothing treatment is performed, the coated paper obtained is excellent in the acceptability of printing inks, and in offset sheet-fed printing, The present invention has been completed by discovering that it has excellent running properties, is less likely to cause show-through or blocking on the back surface of paper, and has good operability.

That is, the coated paper according to the present invention comprises a paper base material and a coating layer containing a pigment and an adhesive as a main component on at least one surface thereof, and the surface of the coating layer is 10 to 10. 1
It is characterized in that it has a convex portion of 000 pieces / mm ² and the glossiness of the white paper is 45 to 80%.

The coating layer has an average particle size of 3.0 to 5
It is preferable to contain spherical particles of 0.0 μm. Further, the paper base material has an average particle size of 3.0 to 50.
Spherical particles of 0 μm are externally applied and coated, 10 to 1000 particles /
It is preferable to have a convex portion of mm ² . Furthermore, the coefficient of static friction of the surface of the coating layer is
C, 50% R.C. H. ) Is preferably 0.2 to 0.7.

As the spherical particles, inorganic pigments and / or organic pigments can be used, and as the organic pigments, solid, hollow and through-hole types can be appropriately selected and used. preferable.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of the inventors of the present invention, as a result of earnest research on maintaining high gloss of coated paper and improving paper feedability and ink show-through during offset printing, It is thought that it is necessary to obtain high gloss while reducing the contact between the papers and the ink show-through to reduce the contact area between the paper surface and the ink, and the surface of the coating layer has a convex shape of 10 to 1000 pieces / mm ² . By having a part, a coated paper having high gloss and good suitability for offset printing was obtained.

It is preferable that the spherical particles used in the present invention have a particle size of 3.0 to 50.0 μm. Further, the number of convex portions existing on the surface of the coating layer is 10 to 1000 / m.
It is in the range of m ² . Compared with the particle size of kaolin or the like used in the main pigment being about 1.0 μm, the spherical particles are coarse particles, and some of the spherical particles are convex on the surface of the coating layer. Even after appearing and smoothing treatment, spherical particles are present on the surface of the coating layer in a convex shape, so that the contact area between the surface of the coating layer and the ink is small and the show-through of the ink is improved.

By the way, when the particle size is smaller than 3.0 μm, or the number of convex portions present on the surface of the coating layer is 10 / m.
When it is less than m ² , gloss is likely to appear, but ink show-through may occur. On the other hand, when the particle diameter is larger than 50.0 μm or when the number of convex portions present on the surface of the coating layer is more than 1000 / mm ² , the show-through effect of the ink is improved, but the gloss is exhibited. It is difficult to obtain the desired gloss, and uneven transfer of ink may occur. From the balance of ink show-through improvement effect and gloss,
Regarding the particle size distribution, it is more preferable that the particle size distribution is a particle size of 5.0 to 30.0 μm, and the number of convex portions present on the coated paper surface is more preferably 20 to 600 pieces / mm ^2. preferable.

The cause of double feeding occurring in the paper feeding section occurs when the adhesion between the paper sheets is high. Generally, the adhesion between papers can be evaluated by the friction coefficient. As in the present application, when the coating layer has a convex portion on the surface, the adhesion between the papers is reduced, so that the occurrence of double feeding can be prevented. By the way, if the convex portion exceeds 50 μm, it will hinder the development of gloss. Where the coefficient of static friction is 0.2
If it is less than the above range, the paper gap may be too slippery and the handling property of the paper may be deteriorated. On the other hand, if it is more than 0.7, the adhesion between the paper sheets may be high and double feeding may occur in the paper feeding section. I have something to do.

Among the spherical particles used in the present invention, examples of the inorganic pigment include light calcium carbonate, magnesium carbonate and the like, and one kind or two or more kinds are appropriately selected and used from these.

Among the spherical particles used in the present invention, solid type, hollow type and through-hole type organic pigments include polystyrene resin, styrene-acrylic copolymer resin, urea resin, melamine resin, Acrylic resins, vinylidene chloride resins, benzoguanamine resins, and the like,
One or two or more of these may be appropriately selected and used.

There is no particular limitation on the manufacturing method and the kind of the paper base pulp, and chemical pulp such as KP, mechanical pulp such as SGP, RGP, BCTMP and CTMP, and deinking pulp can be used. Used paper pulp or non-wood pulp such as kenaf, bagasse, bamboo, straw, hemp, etc., organic synthetic fibers such as polyamide fiber, polyester fiber, polynosic fiber, and inorganic fibers such as glass fiber, ceramic fiber, carbon fiber, etc. Can be used. E
Chlorine-free pulp such as CF pulp and TCF pulp and waste paper pulp are preferably used.

If desired, a filler can be added to the paper base material. 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, and smectite, , Polystyrene resins, urea resins, melamine resins, acrylic resins, vinylidene chloride resins, and organic pigments such as minute hollow particles thereof.

In addition to pulp fiber and filler,
To the extent that the desired effects of the present invention are not impaired, various conventionally used anionic, nonionic, cationic or amphoteric retention improvers, drainage improvers, paper strength enhancers, fixing agents and Various types of internal additive for papermaking such as internal sizing agent can be appropriately selected and used as necessary. Further, an internal additive for papermaking such as a dye, a fluorescent whitening agent, a pH adjusting agent, a defoaming agent, a pitch control agent and a slime control agent may be appropriately added depending on the purpose of the paper.

The papermaking method is not particularly limited. For example, an acidic papermaking method having a papermaking pH of about 4.5, 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, such as weak acidity of about pH 6 to weak alkaline papermaking method of about pH 9 and the like, and the paper machine can be a Fourdrinier paper machine, a twin wire paper machine, a round wire paper machine, A Yankee paper machine can be used as appropriate.

In the paper making process as described above, the spherical pigment is applied to the surface of the paper base material. A two-roll or metering blade type size press coater, a gate roll coater, or the like is used.

As the pigment used in the coated paper of the present invention, in addition to the spherical particles, for example, heavy calcium carbonate, light calcium carbonate, kaolin, calcined kaolin, structural kaolin, deramie kaolin, talc, calcium sulfate, Barium sulfate, titanium dioxide, zinc oxide, alumina, magnesium carbonate, magnesium oxide, silica, magnesium aluminosilicate, fine particle calcium silicate, fine particle magnesium carbonate, fine particle light calcium carbonate, white carbon, bentonite, zeolite, sericite,
Mineral pigments such as smectite, polystyrene resins,
Styrene-acrylic copolymer resin, urea resin, melamine resin, acrylic resin, vinylidene chloride resin,
Organic pigments such as solid type, hollow type, and through-hole type resins such as benzoguanamine-based resins can be used, and one or two or more kinds thereof are appropriately selected and used.

As the adhesive agent, 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, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, gelatin, casein,
Soy protein, natural or semi-synthetic polymer compounds such as natural rubber, polyvinyl alcohol, isoprene, neoprene,
Polydienes such as polybutadiene, polybutene, polyisobutylene, polypropylene, polyalkenes such as polyethylene, vinyl halides, vinyl acetate, styrene,
(Meth) acrylic acid, (meth) acrylic acid ester,
Vinyl-based polymers and copolymers such as (meth) acrylamide and methyl vinyl ether, synthetic rubber latex such as styrene-butadiene-based, methylmethacrylate-butadiene-based, polyurethane-based resin, polyester-based resin, polyamide-based resin, olefin- Examples thereof include synthetic polymer compounds such as maleic anhydride resin and melamine resin. Among these, one kind or two or more kinds are appropriately selected and used according to the purpose.

The mixing ratio of the adhesive is preferably in the range of 5 to 50 parts by mass (solid content) with respect to 100 parts by mass (solid content) of the pigment. By the way, if it is less than 5 parts by mass,
The strength of the coating film of the coating layer is weak, and the coating layer may be peeled off from the printing plate of the rotary press, and the peeled portion may be deposited, which may cause damage to the printing plate. On the other hand, when it exceeds 50 parts by mass, the coating layer becomes dense and the ink fixability may be significantly lowered.

In addition to these pigments and adhesives, various auxiliary agents such as surfactants, pH adjusters, viscosity adjusters, softeners, gloss imparting agents, waxes, dispersants, and flow agents are contained in the coating liquid. Modifier, antistatic agent, stabilizer, antistatic agent, crosslinking agent,
A sizing agent, a fluorescent whitening agent, a coloring agent, an ultraviolet absorber, an antifoaming agent, a water resistant agent, a plasticizer, a lubricant, an antiseptic, a perfume and the like can be appropriately used if necessary.

The coating amount (solid content) of the coating layer of the present invention is 5
~ 20 g / m < ² >, preferably 8-15 g / m < ² > is required. If the coating amount is less than 5 g / m ² , the irregularities on the surface of the paper substrate cannot be sufficiently covered, so that the acceptability of the printing ink may be significantly reduced. On the other hand, when it exceeds 20 g / m ² , operability such as poor drying property at the time of coating is deteriorated and manufacturing cost is also increased.

The coating method for forming the coating layer is a generally known coating apparatus 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. An apparatus 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 is appropriately used.

The coating layer is formed on both sides of the paper base material, and if necessary, one layer or two or more intermediate layers may be provided to form a multilayer structure. In the case of double-sided coating or multi-layer structure, each coating liquid does not have to have the same or the same coating amount, and may be appropriately adjusted and blended according to the required quality level, and is not particularly limited. is not. When a coating layer is provided on one side of the paper substrate, a synthetic resin layer, a coating layer composed of pigment and adhesive, and an antistatic layer are provided on the back side to prevent curling, impart printability, and feed and discharge paper. It is also possible to add suitability and the like. It is also possible to add various properties to the back surface of the paper substrate, for example, post-processing such as adhesion, heat sensitivity, magnetism, flame retardancy, heat resistance, water resistance, oil resistance, anti-slip, etc. Is.

In the present invention, after the coating liquid layer is provided on the paper substrate, it is subjected to smoothing treatment in a usual drying process, a surface treatment process and the like to have a water content of 3 to 10%, preferably 4 to 8%. It is adjusted to finish and finished.

Further, the smoothing treatment is carried out by a smoothing treatment device such as a normal super calender, a gross calender, a soft calender, etc., which is appropriately used on-machine or off-machine, and the form of a pressure device, The number of pressure nips, heating, etc. are appropriately adjusted according to a normal smoothing apparatus.

Since the coated paper which has been subjected to the smoothing treatment needs to have the texture of the printing paper, the J
The white paper glossiness at an incident / light receiving angle of 75 degrees based on IS Z 8741 is 45 to 80%, preferably 55 to 80%.
Is.

If the glossiness is less than 45%, the appearance of white paper or desired glossiness may not be obtained, while the glossiness is 8%.
When it is higher than 0%, even if the spherical particles used in the present invention are used, the convex portions of the paper surface enter the coating layer during the smoothing treatment, and the offset of the ink during offset printing is not improved. Sometimes.

The coated paper obtained by the above method can be used not only as an offset printing paper, but also as an image recording paper of a non-impact printing system such as an electrophotographic system, a thermal transfer system, an inkjet system.

[0032]

EXAMPLES The present invention will be described in more detail below with reference to examples, but of course the present invention is not limited to these ranges. In addition, "parts" and "%" in the examples mean "parts by mass (solid content)" and "mass%" unless otherwise specified.

Example 1 [Preparation of substrate] LBKP (freeness (CSF) = 45)
0 ml) 90 parts, NBKP (freeness (CSF) = 4
Light calcium carbonate (PC: made by Shiraishi Calcium) was added to 10 parts of pulp slurry to give 5 parts, and 1.5 parts of starch, 0.1 part of alkenyl succinic anhydride and sulfuric acid per pulp were added. Paper is made with a Fourdrinier paper machine using 0.6 part of banded paper stock, and in the paper making process, it is applied with a size press machine so that the following coating amount becomes 1 g / m ^{2 in} dry mass. Then, it was dried and smoothed by a machine calender to have a Beck smoothness of 30 seconds to obtain a base paper having a basis weight of 80 g / m ² (hereinafter referred to as a paper base material).

[Preparation and coating of coating liquid] 96 parts of UW-90 (component; kaolin, manufactured by Engelhard) and spherical particles
(Component: Light calcium carbonate with a diameter of 10 μm, manufactured by Yonejo Lime Industry Co., Ltd.) To 4 parts, 0.2 parts of sodium polyacrylate (trade name: Aron A-9, manufactured by Toagosei Co., Ltd.) as a dispersant was added, and choles Water was dispersed using a disperser to prepare a pigment slurry. 3.0 parts of esterified starch (trade name; Petrocoat C-8, manufactured by Nitto Kagaku) and styrene-butadiene copolymer latex (trade name; T) were added to the pigment slurry.
(2550K JSR) 10 parts were added and stirred, and water was further added to prepare a coating liquid having a solid content concentration of 60%.

[Formation of Coating Layer on Paper Substrate] The coating liquid thus obtained was dried at a rate of 10 g / m 2 on one side of the above-mentioned paper substrate.
Both sides are coated using a blade coater so as to be ^2, and the paper is passed with a super calender pressure nip composed of a metal roll and an elastic roll at a linear pressure of 65 kg / cm, and a basis weight of 104 g / m ^2. I got coated paper. The surface of the coating layer had 300 convex portions per 1 mm ² .

Example 2 Using the coating liquid used in Example 1, the coating amount was 5 per side.
A coated paper was prepared and evaluated in the same manner as in Example 1 except that the content was changed to g / m ² . The surface of the coating layer had 300 convex portions per 1 mm ² .

Example 3 96 parts of UW-90 (component: kaolin, manufactured by Engelhard) used in Example 1 and spherical particles (component: diameter 10 μm)
m light calcium carbonate, Yonejo Lime Industry Co., Ltd.) 4 parts,
UW-90 (component; kaolin, manufactured by Engelhard) 9
A coated paper was prepared and evaluated in the same manner as in Example 1 except that 2 parts and 8 parts of spherical particles (component; light calcium carbonate having a diameter of 10 μm, manufactured by Yonejo Lime Industry Co., Ltd.) were used. The surface of the coating layer had 300 convex portions per 1 mm ² .

Example 4 96 parts of UW-90 (component: kaolin, manufactured by Engelhard Co.) used in Example 1 and spherical particles (component: diameter 10 μm)
m light calcium carbonate, Yonejo Lime Industry Co., Ltd.) 4 parts,
UW-90 (component; kaolin, manufactured by Engelhard) 8
A coated paper was prepared and evaluated in the same manner as in Example 1 except that 5 parts and spherical particles (component; light calcium carbonate having a diameter of 3 μm, manufactured by Yonejo Lime Industry Co., Ltd.) were changed to 15 parts. The surface of the coating layer had 300 convex portions per 1 mm ² .

Example 5 96 parts of UW-90 (component: kaolin, manufactured by Engelhard) used in Example 1 and spherical particles (component: diameter 10 μm)
m light calcium carbonate, Yonejo Lime Industry Co., Ltd.) 4 parts, U
W-90 (component; kaolin, manufactured by Engelhard) 99
Parts and spherical particles (component; light calcium carbonate having a diameter of 20 μm, manufactured by Yonejo Lime Industry Co., Ltd.) were changed to 1 part, and coated paper was prepared and evaluated in the same manner as in Example 1. The surface of the coating layer had 300 convex portions per 1 mm ² .

Example 6 96 parts of UW-90 (component: kaolin, manufactured by Engelhard) used in Example 1 and spherical particles (component: diameter 10 μm)
m light calcium carbonate, Yonejo Lime Industry Co., Ltd.) 4 parts,
UW-90 (component; kaolin, manufactured by Engelhard) 9
A coated paper was prepared and evaluated in the same manner as in Example 1 except that the content was changed to 9.8 parts and 0.2 parts of spherical particles (component; light calcium carbonate having a diameter of 10 μm, manufactured by Yonejo Lime Industry Co., Ltd.). The surface of the coating layer had 10 convex portions per 1 mm ² .

Example 7 96 parts of UW-90 (component: kaolin, manufactured by Engelhard) used in Example 1 and spherical particles (component: diameter 10 μm)
m light calcium carbonate, Yonejo Lime Industry Co., Ltd.) 4 parts, U
W-90 (ingredient; Kaolin, manufactured by Engelhard) 88
Parts and spherical particles (component; light calcium carbonate having a diameter of 10 μm, manufactured by Yonejo Lime Industry Co., Ltd.) were changed to 12 parts, and coated paper was prepared and evaluated in the same manner as in Example 1. The surface of the coating layer had 1000 convex portions per 1 mm ² .

Example 8 The spherical particles used in Example 1 (component; light calcium carbonate having a diameter of 10 μm, manufactured by Yonejo Lime Industry Co., Ltd.) were converted into spherical polyethylene (diameter 25 μm, manufactured by Mitsui Chemicals, Inc .: Miperon XM-22).
1 U) was changed, the compounding amount was changed to 4 parts, and the glossiness was adjusted to 55%. A coated paper was prepared and evaluated in the same manner as in Example 1. The surface of the coating layer has a surface area of 300 per mm ^2.
It had a number of convex portions.

Example 9 [Preparation of substrate] LBKP (freeness (CSF) = 45)
0 ml) 90 parts, NBKP (freeness (CSF) = 4
Light calcium carbonate (PC: made by Shiraishi Calcium) was added to 10 parts of pulp slurry to give 5 parts, and 1.5 parts of starch, 0.1 part of alkenyl succinic anhydride and sulfuric acid per pulp were added. Using a stock with the addition of 0.6 part of a band, paper making was carried out with a Fourdrinier paper machine, and during the paper making process, the following coating liquid was applied so that the coating amount was 1.5 g / m ^{2 in} dry mass. A base paper having a basis weight of 80 g / m ² (hereinafter, referred to as a paper base material) is obtained by applying it with a size press machine, drying it, and smoothing it with a machine calender so that the Bekk smoothness is 10 seconds. It was The surface of the base paper is 4 per 1 mm ^2.
It had 00 convex portions. "Size press coating liquid" Spherical particles (light calcium carbonate with a diameter of 20 μm, made by Yonejo Lime Industry Co., Ltd.) 10 parts Ace A (oxidized starch, made by Oji Corn Starch Co., Ltd.) 90 parts

[Preparation and coating of coating liquid] 96 parts of UW-90 (component; kaolin, manufactured by Engelhard) and Hydrocarb K9 (component: ground calcium carbonate, manufactured by Bihoku Kouka Co., Ltd.)
4 parts of sodium polyacrylate as a dispersant (trade name;
0.2 parts of Aron A-9, manufactured by Toagosei Co., Ltd.) was added, and the mixture was dispersed in water using a Choles disperser to prepare a pigment slurry.
3.0 parts of esterified starch (trade name; Petrocoat C-8, manufactured by Nitto Kagaku) and styrene-butadiene copolymer latex (trade name; T-2550) were added to the pigment slurry.
K, manufactured by JSR) was added and stirred, and water was further added to prepare a coating liquid having a solid content concentration of 60%.

[Formation of Coating Layer on Paper Base Material] The obtained coating liquid is 10 g / m ^{2 in} dry mass per one side of the paper base material.
Coated on both sides using a blade coater and passed through the pressure nip of a super calendar composed of metal rolls and elastic rolls, adjusted to have a gloss of 55%, and weighed. To obtain a coated paper having a weight of 104 g / m ² . The surface of the coating layer had 300 convex portions per 1 mm ² .

Example 10 In Example 9, during the papermaking process, the coating liquid of the size press device was lowered.
A coated paper was prepared in the same manner as in Example 9 except that the changes were made as described below.
Made and evaluated. 1 mm on the surface of the base paper ^TwoHit
It had 300 convex portions. On the surface of the coating layer
Is 1 mm^TwoIt had 200 convex portions per hit. " Size press coating liquid " Spherical particle 10 parts (Polyethylene with a diameter of 25 μm; trade name Miperon XM-221U, manufactured by Mitsui Chemicals, Inc.)   Ace A (oxidized starch, made by Oji Corn Starch) 90 parts

Example 11 [Preparation of substrate] LBKP (freeness (CSF) = 45)
0 ml) 90 parts, NBKP (freeness (CSF) = 4
Light calcium carbonate (PC: made by Shiraishi Calcium) was added to 10 parts of pulp slurry to give 5 parts, and 1.5 parts of starch, 0.1 part of alkenyl succinic anhydride and sulfuric acid per pulp were added. Size-press the following coating liquid so as to make a coating amount of 1 g / m ^{2 in a} dry mass during the papermaking process using a fourdrinier paper machine using 0.6% banded paper stock. A base paper having a basis weight of 80 g / m ² (hereinafter, referred to as a paper base material) was obtained by coating with an apparatus, drying and smoothing with a machine calender so that the Bekk smoothness was 20 seconds. ² per 1 mm ^{2 on} the surface of the base paper
It had 00 convex portions. "Size press coating liquid" Spherical particles 10 parts (polyethylene with a diameter of 25 μm, trade name: Miperon XM-221U, manufactured by Mitsui Chemicals, Inc.) Ace A (oxidized starch, manufactured by Oji Corn Starch) 90 parts

[Preparation and Application of Coating Liquid] 96 parts of UW-90 (component; kaolin, manufactured by Engelhard) and spherical polyethylene (diameter 25 μm, manufactured by Mitsui Chemicals: Miperon XM)
-221U), 0.2 parts of sodium polyacrylate (trade name; Aron A-9, manufactured by Toagosei Co., Ltd.) as a dispersant was added to 4 parts, and the mixture was water-dispersed using a Choles disperser to prepare a pigment slurry. . 3.0 parts of esterified starch (trade name; Petrocoat C-8, manufactured by Nitto Kagaku) and styrene-butadiene copolymer latex (trade name; T) were added to the pigment slurry.
(2550K JSR) 10 parts were added and stirred, and water was further added to prepare a coating liquid having a solid content concentration of 60%.

[Formation of Coating Layer on Paper Substrate] The obtained coating liquid is 10 g / m ^{2 in} dry mass per one side of the above-mentioned paper substrate.
Coated on both sides using a blade coater and passed through the pressure nip of a super calendar composed of metal rolls and elastic rolls, adjusted to have a gloss of 55%, and weighed. To obtain a coated paper having a weight of 104 g / m ² . The surface of the coating layer had 400 convex portions per 1 mm ² .

Comparative Example 1 96 parts of UW-90 (component: kaolin, manufactured by Engelhard) used in Example 1 and spherical particles (component: diameter 10 μm)
m light calcium carbonate, Yonejo Lime Industry Co., Ltd.) 4 parts,
UW-90 (Component: Kaolin, manufactured by Engelhard) 1
A coated paper was prepared and evaluated in the same manner as in Example 1 except that only 00 parts was changed. No convex portion could be observed on the surface of the coating layer.

Comparative Example 2 96 parts of UW-90 (component: kaolin, manufactured by Engelhard) used in Example 1 and spherical particles (component: diameter 10 μm)
m light calcium carbonate, Yonejo Lime Industry Co., Ltd.) 4 parts,
UW-90 (component; kaolin, manufactured by Engelhard) 7
A coated paper was prepared and evaluated in the same manner as in Example 1 except that 6 parts and spherical particles (component; light calcium carbonate having a diameter of 10 μm, manufactured by Yonejo Lime Industry Co., Ltd.) were changed to 24 parts. The surface of the coating layer had 2000 convex portions per 1 mm ² .

Comparative Example 3 96 parts of UW-90 (component: Kaolin, manufactured by Engelhard) used in Example 1 and spherical particles (component: diameter 10 μm)
m light calcium carbonate, Yonejo Lime Industry Co., Ltd.) 4 parts,
UW-90 (component; kaolin, manufactured by Engelhard) 9
A coated paper was prepared and evaluated in the same manner as in Example 1 except that the content was changed to 9.5 parts and 0.5 parts of spherical particles (component; light calcium carbonate having a diameter of 35 μm, manufactured by Yonejo Lime Industry Co., Ltd.). The surface of the coating layer had 300 convex portions per 1 mm ² .

Comparative Example 4 96 parts of UW-90 (component: kaolin, manufactured by Engelhard) used in Example 1 and spherical particles (component: diameter 10 μm)
m light calcium carbonate, Yonejo Lime Industry Co., Ltd.) 4 parts,
UW-90 (component; kaolin, manufactured by Engelhard) 8
A coated paper was prepared and evaluated in the same manner as in Example 1 except that 0 parts and spherical particles (component; light calcium carbonate having a diameter of 2 μm, manufactured by Yonejo Lime Industry Co., Ltd.) were changed to 2 parts. The surface of the coating layer had 300 convex portions per 1 mm ² .

Comparative Example 5 [Preparation of base material] LBKP (freeness (CSF) = 45)
0 ml) 90 parts, NBKP (freeness (CSF) = 4
Light calcium carbonate (PC: made by Shiraishi Calcium) was added to 10 parts of pulp slurry to give 5 parts, and 1.5 parts of starch, 0.1 part of alkenyl succinic anhydride and sulfuric acid per pulp were added. Using a stock with the addition of 0.6 part of a band, paper making was carried out with a Fourdrinier paper machine, and during the paper making process, the following coating liquid was applied so that the coating amount was 1.5 g / m ^{2 in} dry mass. A base paper having a basis weight of 80 g / m ² (hereinafter, referred to as a paper base material) is obtained by applying it with a size press machine, drying it, and smoothing it with a machine calender so that the Bekk smoothness is 10 seconds. It was 5 mm ² per 1 mm ^{2 on} the surface of the base paper
It had 00 convex portions. "Size press coating liquid" Spherical particles (light calcium carbonate with a diameter of 2 μm, made by Yonejo Lime Industry Co., Ltd.) 10 parts Ace A (oxidized starch, made by Oji Corn Starch Co., Ltd.) 90 parts

[Preparation and coating of coating liquid] 96 parts of UW-90 (component; kaolin, manufactured by Engelhard) and Hydrocarb K9 (component: ground calcium carbonate, manufactured by Bihoku Kouka Co., Ltd.)
4 parts of sodium polyacrylate as a dispersant (trade name;
0.2 parts of Aron A-9, manufactured by Toagosei Co., Ltd.) was added, and the mixture was dispersed in water using a Choles disperser to prepare a pigment slurry.
3.0 parts of esterified starch (trade name; Petrocoat C-8, manufactured by Nitto Kagaku) and styrene-butadiene copolymer latex (trade name; T-2550) were added to the pigment slurry.
K, manufactured by JSR) was added and stirred, and water was further added to prepare a coating liquid having a solid content concentration of 60%.

[Formation of Coating Layer on Paper Base Material] The obtained coating liquid is 10 g / m ^{2 in} dry mass per one side of the paper base material.
Coated on both sides using a blade coater and passed through the pressure nip of a super calendar composed of metal rolls and elastic rolls, adjusted to have a gloss of 55%, and weighed. To obtain a coated paper having a weight of 104 g / m ² . The surface of the coating layer had 0 convex portions per 1 mm ² .

[Counting of the convex portions on the surface of the coating layer] The convex portions on the surface of the coating layer were counted by magnifying (100) times with an electron microscope. The results are shown in Table 1.

[Printing of coated paper] An offset four-color printing machine manufactured by Mitsubishi Heavy Industries, Ltd. was used as a printing machine, and printing was performed under the following conditions: environment of 20 ° C., 65% RH printing speed: 10000 sheets / hour number of printed sheets: 10000 Sheet drying conditions: Use a gas heater to adjust the paper surface temperature to 150 ° C Powder: Silicone-coated starch, particle size 25 μm

(Evaluation of ink show-through on back side) 10000
The stain on the back surface of the paper after printing one sheet was evaluated according to the following evaluation criteria. ◯: Dirt is not seen. There is no problem in practical use and the quality is excellent. Δ: Some dirt is seen. There is no problem in practical use. X: Dirt is often seen. There are practical problems and the quality is poor.

(Evaluation of glossiness of blank paper) JIS Z 8741
The glossiness was measured under the condition that the incident angle and the light receiving angle were 75 degrees. The measuring device is GLOSS ME manufactured by Murakami Color Research Institute.
TER MODEL GM-26D was used.

(Evaluation of coefficient of friction between papers) The coefficient of friction between papers of the obtained coated paper was measured under ISO environment (23 ° C., 50% RH).
Then, it measured using the tensile tester.

(Evaluation of paper running property) A color copying machine IPSiO Color2100 manufactured by RICOH was used.
A color original was used to continuously print 1000 sheets, and the running property of the paper was evaluated. A: There is no double feeding or jamming of paper. ◯: 1 to 2 sheets of double feed or jamming of paper. Δ: 3 to 4 sheets are fed or jammed. ×: Double feeding or jamming of paper is 5 or more.

[Evaluation of Paper Base Material and Coated Paper] From the above,
The resulting coated paper was evaluated for ink show-through on the back surface, white paper glossiness, coefficient of friction between papers, and paper running property, and the results are shown in Table 1.

[0064]

[Table 1]

[0065]

EFFECTS OF THE INVENTION The coated paper according to the present invention has a high glossiness of white paper and excellent paper running property in a printing machine, and in offset sheet-fed printing, show-through and blocking occur on the back surface of the paper after printing. It is a coated paper that is difficult to produce and provides a high-quality image, and is extremely useful in practice.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4L055 AA02 AA03 AC06 AG12 AG27                       AG41 AG47 AG48 AG59 AG63                       AG76 AG89 AG94 AG97 AH01                       AH02 AH09 AH12 AH37 AH50                       BE08 EA11 EA16 EA27 FA15                       GA19

Claims (4)

[Claims] 1. A coated paper comprising a paper base material and a coating layer containing a pigment and an adhesive as a main component on at least one surface thereof, wherein the surface of the coating layer is 10 to 1000 pieces / mm. ^Two
2. The coated paper, which has a convex portion and has a white paper gloss of 45 to 80%. 2. An average particle size of 3.0 to 5 in the coating layer.
The coated paper according to claim 1, which contains spherical particles of 0.0 μm. 3. The paper base material is externally coated on its surface with spherical particles having an average particle diameter of 3.0 to 50.0 μm.
The coated paper according to claim 1, which has a convex portion of about 1000 pieces / mm ² . 4. The static friction coefficient of the surface of the coating layer is ISO
The coated paper according to any one of claims 1 to 3, which has an environment (23 ° C, 50% RH) of 0.2 to 0.7.