JP2000110094A - Composition for coated paper for gravure printing and coated paper for gravure printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated paper for gravure printing which has excellent surface strength, rigidity and blocking resistance and has little occurrence of missing dots, and a composition used for producing such a coated paper for gravure printing. provide. . The copolymer latex contains an adhesive composed of a pigment, hollow polymer particles, a copolymer latex, and starch, and the copolymer latex has a number average particle size of 0.06 to 0.2 μm. Has a glass transition temperature of −50 to + 45 ° C., and the weight ratio of the copolymer latex / starch is 80/20 in terms of solid content.
A base paper is coated with a composition for coated paper for gravure printing, which is 5/95.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for coated paper for gravure printing and a coated paper for gravure printing. More specifically, a coating for gravure printing comprising a pigment, hollow polymer particles and an adhesive comprising a specific copolymer latex and starch, wherein the weight ratio of the copolymer latex / the starch is in a specific range. The present invention relates to a paper composition and a coated paper for gravure printing obtained by applying the composition to base paper.

[0002]

2. Description of the Related Art In recent years, gravure printing, which has a high ink density and can provide colorful printed matter, is often used for printing coated paper. Coated paper used for gravure printing is required not only to have excellent surface strength, rigidity and blocking resistance, but also to be free from the occurrence of missing dots.

[0003] Conventionally, in order to obtain a coated paper with less occurrence of missing dots, a copolymer latex having a glass transition temperature of -40 ° C or less has been used as an adhesive, and a surface treatment has been performed under a high temperature and a high pressure using a calendar. Has been used. However, the coated paper for gravure printing obtained by this method was inferior in surface strength, rigidity, and blocking resistance, although generation of missing dots was small. If the coated paper has poor blocking resistance and surface strength, the rolls become dirty during calendering, resulting in poor operability, and in gravure printing, the printed surface is peeled off to reduce the value of the printed material. Problems occur. A printed matter having low rigidity is difficult to handle, and the value as a printed matter is undesirably reduced.

It is known that the stiffness of coated paper has a correlation with the paper thickness of the coated paper, and it is known that as a method of improving the stiffness, it is particularly effective to perform calendering at low temperature and low pressure. ing. However, since the conventional method requires a high-temperature and high-pressure calendering treatment, it has not been possible to obtain a coated paper with less occurrence of missing dots and excellent rigidity. Therefore, it is strongly desired that the coated paper for gravure printing has excellent surface strength, rigidity, and blocking resistance, and generates few missing dots.

JP-A-64-20396 discloses a coating containing 2 to 20% by weight of a non-film-forming resin particle having an outer diameter of 0.2 to 0.6 μm and a void therein as a pigment. A gravure coated paper coated with the composition is disclosed. This publication describes a method of combining a synthetic resin emulsion and starch as an adhesive. However, this method does not limit the synthetic resin emulsion, and this publication does not describe the effect of the use ratio of the synthetic resin emulsion and starch on gravure printing.

Japanese Patent Application Laid-Open No. 5-125695 discloses a coating for gravure printing in which a specific base paper is provided with a coating layer containing 5 to 40% by weight of 0.8 to 6 μm hollow polymer particles as a pigment. Papermaking is disclosed. This method requires the use of base paper containing 10 to 50% by weight of filler. However, when base paper containing a large amount of filler is used, there has been a problem that paper peeling easily occurs during printing.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a coated paper for gravure printing which is excellent in surface strength, rigidity and blocking resistance, and has little occurrence of missing dots. Still another object of the present invention is to provide a composition used for producing the above-mentioned coated paper for gravure printing.

[0008]

Means for Solving the Problems The present inventors have repeatedly studied an adhesive in order to achieve the above object.
If the adhesive is composed of a specific copolymer latex and starch, and the weight ratio of the copolymer latex to starch is in a specific range, the desired coated paper for gravure printing can be obtained. The present invention has been completed based on this finding.

Thus, according to the present invention, an adhesive comprising a pigment, hollow polymer particles and a copolymer latex and starch is contained, and the number average particle diameter of the copolymer latex is 0.06 to 0. 2 μm, the glass transition temperature of the copolymer constituting the copolymer latex is −50 to + 45 ° C., and the weight ratio of the copolymer latex / the starch is 80/20 to 5 in terms of solid content. / 95, a composition for coated paper for gravure printing. Further, according to the present invention, there is provided a coated paper for gravure printing obtained by coating the above composition on base paper.

Hereinafter, the present invention will be described in detail. The composition for coated paper for gravure printing of the present invention (hereinafter referred to as “coating composition”) comprises a pigment, hollow polymer particles, a copolymer latex, and starch.

The pigment used in the present invention is not particularly limited, and examples thereof include clay, calcium carbonate, titanium oxide, aluminum hydroxide, satin white, silica, talc,
Inorganic pigments such as barium sulfate; plastic pigments,
Organic pigments such as a binder pigment are exemplified. These can be used alone or in combination of two or more.

The hollow polymer particles used in the present invention are polymer particles having one or more voids (hollows) inside the particles. The hollow polymer particles preferably have a thermoplastic resin as a shell in order to reduce the occurrence of missing dots.

Examples of hollow polymer particles having a thermoplastic resin as a shell include styrene resins such as polystyrene and poly-β-methylstyrene; polymethyl methacrylate, polyethyl methacrylate, polyisopropyl methacrylate, and polyisobutyl methacrylate. , Acrylic resins such as polyacrylonitrile and polymethacrylonitrile; polyvinyl chloride, polytetrafluoroethylene, polyvinyl alcohol, poly-o-vinylbenzyl alcohol, poly-m-
Vinyl benzyl alcohol, poly-p-vinyl benzyl alcohol, polyvinyl formal, polyvinyl acetal, polyvinyl propional, polyvinyl butyral, polyvinyl isobutyral, polyvinyl tertiary butyl ether, polyvinyl pyrrolidone, polyvinyl carbazole, cellulose acetate, cellulose triacetate, polycarbonate, etc. Various things can be illustrated. Further, those having a shell made of a copolymer or the like obtained by variously combining monomers used for each of the above polymers can also be used. The hollow polymer particles having these thermoplastic resins as shells are not limited by the production method.

[0014] Further, these resins are preferably hollow polymer particles having a multilayer structure, since a high porosity can be obtained, and among them, polystyrene polymer particles / poly (meth) acrylate polymer are preferable. Hollow polymer particles forming a multilayer structure are particularly preferred.

The outer diameter of the hollow polymer particles used in the present invention is as follows:
Although not particularly limited, 0.3 to 10 μm is preferable,
0.5-8 μm is more preferred.

The porosity of the hollow polymer particles used in the present invention (the ratio of the internal void volume to the total particle volume) is not particularly limited, but is preferably at least 10%, more preferably at least 30%. It is considered that the larger the porosity, the more the coated paper is easily smoothed by the calendering treatment, so that the occurrence of missing dots is reduced. However, it is actually difficult to produce hollow polymer particles having a porosity of 90% or more.

The hollow polymer particles used in the present invention are not limited by the production method. Examples of the method for producing hollow polymer particles include those described in JP-A-64-1704, JP-A-5-279409, JP-A-6-248012, and JP-A-10-11018. Is mentioned.

The amount of the hollow polymer particles used in the present invention is 0.1 to 30 parts by weight, preferably 0.5 to 25 parts by weight, more preferably 1 to 20 parts by weight based on 100 parts by weight of the pigment. is there. If the amount is less than 0.1 parts by weight, many missing dots are generated. If the amount exceeds 30 parts by weight, the viscosity of the coating composition will increase, or the surface strength of the coated paper will decrease. If the solid content concentration is lowered in order to lower the viscosity of the coating composition, mist is generated at the time of coating, and the coated paper tends to be insufficiently dried.

The adhesive used in the present invention comprises a copolymer latex and starch. The number average particle diameter of the copolymer latex needs to be 0.06 to 0.2 μm.
Preferably it is 0.07-0.18 micrometers, More preferably, it is 0.08-0.15 micrometers. When the thickness is less than 0.06 μm, the rigidity of the coated paper is reduced, and more missing dots are generated. If it exceeds 0.2 μm, the surface strength of the coated paper will be poor.

In the present invention, the copolymer constituting the copolymer latex must have a glass transition temperature (hereinafter, referred to as "Tg") of -50 to + 45 ° C.
Preferably -50 to + 40 ° C, more preferably -50 to
+ 35 ° C. If the temperature is lower than −50 ° C., the surface strength and rigidity of the coated paper decrease, and the blocking resistance further decreases. +
If the temperature exceeds 45 ° C., the surface strength of the coated paper decreases,
Further, many missing dots are generated.

In the present invention, the tetrahydrofuran-insoluble content (hereinafter referred to as "THF-insoluble content") of the copolymer constituting the copolymer latex is not particularly limited, but is usually 10 to 95% by weight, preferably 10 to 95% by weight. Is 20 to 90
%, More preferably 30 to 85% by weight. 10
When the amount is less than% by weight, there is a tendency that the roll is easily stained in the calendering process. If it exceeds 95% by weight, the surface strength of the coated paper tends to decrease.

The copolymer latex used in the present invention is not particularly limited as long as the number average particle diameter and Tg are respectively in the above ranges. Specific examples of the copolymer latex include acrylonitrile-butadiene copolymer latex, styrene-butadiene copolymer latex, carboxy-modified styrene-butadiene copolymer latex, and styrene-butadiene- (meth) acrylate copolymer latex. Conjugated diene copolymer latex such as carboxy-modified styrene-butadiene- (meth) acrylate copolymer latex; (meth) acrylate copolymer latex, styrene- (meth) acrylate copolymer latex And (meth) acrylate-based copolymer latex such as vinyl acetate- (meth) acrylate copolymer latex.

Among the above copolymers, styrene-butadiene copolymer latex, especially carboxy-modified styrene-butadiene copolymer latex, especially conjugated diene monomer, aromatic vinyl monomer, and ethylenically unsaturated monomer A copolymer latex obtained by copolymerizing a carboxylic acid monomer and, if necessary, a monomer copolymerizable therewith is preferably used.

As the conjugated diene monomer, for example,
1,3-butadiene, isoprene, 2,3-dimethyl-
Examples thereof include 1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, and chloroprene. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, β-methylstyrene, o-
Vinyltoluene, m-vinyltoluene, p-vinyltoluene, o-chlorostyrene, m-chlorostyrene, p-
Chlorostyrene, hydroxymethylstyrene, halogenated styrene and the like can be mentioned. Examples of the ethylenically unsaturated carboxylic acid monomer include, for example, acrylic acid, methacrylic acid, crotonic acid, fumaric acid, maleic acid, mono- or dicarboxylic acids such as itaconic acid, anhydrides of dicarboxylic acids,
And monoalkyl esters of dicarboxylic acids.

The monomers copolymerizable with the above-mentioned monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate,
-Ethylenically unsaturated carboxylic acid ester monomers such as ethylhexyl acrylate, glycidyl (meth) acrylate and lauryl (meth) acrylate; ethylenically unsaturated carboxylic acid amides such as (meth) acrylamide and N-methylol (meth) acrylamide System monomer;
(Meth) acrylonitrile, fumaronitrile, 2-chloropropenenitrile, 2-ethylpropenenitrile, 2
-Ethylenically unsaturated nitrile monomers such as -propylpropenenitrile and 2-butenenitrile; crosslinkable monomers such as divinylbenzene, ethylene glycol dimethacrylate and 1,3-butylene glycol dimethacrylate; ethylene and vinyl acetate Is mentioned.

The starch used in the present invention is not particularly limited. For example, starch which has been chemically treated such as oxidized starch, etherified starch, esterified starch, enzyme-modified starch; corn, rice, wheat, potato, sweet potato, banana, etc. Non-chemically treated starch obtained from cereals and the like. Of the above starches, chemically treated starches, especially oxidized starches,
Esterified starch is preferred. In the present invention, the above starch may be used alone, or two or more types may be used in combination. Further, the starch used in the present invention is not limited by its molecular weight.

The adhesive used in the present invention has a copolymer latex / starch weight ratio of 80/20 to 80/20 in terms of solid content.
It needs to be 5/95. Preferably 75/2
5/10/90, more preferably 70 / 30-15 / 8
5 If the amount of the copolymer latex exceeds this range, the rigidity of the coated paper decreases. Also,
If the amount of starch used exceeds this range, many missing dots are generated.

The amount of the adhesive comprising the copolymer latex and starch is 2 to 30 parts by weight, preferably 3 to 25 parts by weight, more preferably 3 to 25 parts by weight, based on 100 parts by weight of the pigment. -20 parts by weight. If the amount is less than 2 parts by weight, the surface strength of the coated paper is insufficient, and the printed surface is peeled off. If the amount is more than 30 parts by weight, smoothing is difficult to improve even by calendering, so that many missing dots are generated.

The coating composition of the present invention may contain, if necessary, auxiliary materials such as dyes, dispersants, pH adjusters, lubricants, release agents, viscosity adjusters, defoamers, and preservatives. can do. The types of these auxiliary materials are not particularly limited. Further, the usage amount, addition concentration, addition method, and the like of these auxiliary materials can be arbitrarily selected within a range that does not impair the effects of the present invention.

The solid content concentration of the coating composition of the present invention is not particularly limited, but is usually 20 to 70% by weight, preferably 30 to 65% by weight. If it is less than 10% by weight, mist is generated at the time of coating, or the coated paper tends to be insufficiently dried. If it exceeds 70% by weight, the fluidity of the coating composition will decrease, making it difficult to adjust the coating amount.

The method for preparing the coating composition of the present invention is generally carried out by adding a pigment, a hollow polymer particle, a copolymer latex, a starch, water, and, if necessary, Charge the ingredients and stir to prepare.

The coated paper for gravure printing of the present invention is obtained by coating the coating composition of the present invention on one or both sides of a base paper and drying it.

The basis weight of the base paper used for producing the coated paper for gravure printing of the present invention is not particularly limited, but is usually 20 to
200 g / m ^2, preferably 30~160g / m ^2.

In order to obtain the coated paper for gravure printing of the present invention, the base paper is coated with the coating composition of the present invention in an amount of 3 to 3 per side.
Apply 20 g / m ² (dry weight).

Although the coating method is not particularly limited, it is usually carried out using a coating machine such as a gate roll coater, blade coater, bill blade coater, bar coater, curtain coater, air knife coater and the like.

The method of drying after coating is not particularly limited.
Usually, the drying is performed using a dryer such as a steam dryer, a hot air dryer or an electric heater dryer. The drying temperature and drying time vary depending on the dryer and the coating speed, but are usually 80 to 180.
It is about 0.03 to 10 seconds at ° C.

After the coating composition of the present invention is applied to base paper and dried, the coated paper is subjected to calendering using various calendars such as a super calender, a gloss calender, a soft calender, and a machine calender. Can be. The roll temperature and the linear pressure of the calender are not particularly limited, but usually the roll temperature is about 40 to 200 ° C and the linear pressure is about 60 to 200 kg / cm.

[0038]

The present invention will be described below in more detail with reference to Examples, Comparative Examples and Reference Examples. In the Examples, Comparative Examples and Reference Examples, parts and% are based on weight, and the weight of the copolymer latex is in terms of solid content. [Evaluation Method of Copolymer Latex] The methods for measuring the number average particle diameter of the copolymer latex and the Tg and THF insoluble content of the copolymer constituting the copolymer latex are as follows.

(Number average particle size) The copolymer latex whose pH has been adjusted to 8 is measured using COULTER LS230 (manufactured by Coulter KK).

(Tg) A copolymer latex having a pH of 8 was cast on a glass plate held horizontally so that the thickness of the dried film was about 2 mm, and the temperature was 23 ° C. and the humidity was 65%.
Dry naturally for 48 hours in a constant temperature and humidity room kept at a constant temperature. Peel off the obtained film from the glass plate, 2mm × 2mm
Then cut about 10mg into a special container and cover it. This dedicated container was set on a differential scanning calorimeter (Model RDC220, manufactured by Seiko Denshi Co., Ltd.), and the initial temperature-
The measurement is performed under the conditions of 100 ° C., an end temperature of 100 ° C., and a heating rate of 10 ° C./min.

(THF insoluble content) A copolymer latex of pH 8 was cast on a glass plate held horizontally so that the thickness of the dried film was about 2 mm.
Dry naturally for 48 hours in a constant temperature and humidity room maintained at 65 ° C. and a humidity of 65%. The obtained film was peeled off from the glass plate and cut into 2 mm x 2 mm, and about 0.3 g of the film was cut into a box-shaped 80 mm.
It is precisely weighed (weight: Bg) and put into a mesh wire net (weight: Ag). This box-shaped 80 mesh wire mesh is put in a glass beaker, 100 ml of tetrahydrofuran is poured, and the mixture is left at room temperature for 48 hours. After standing for 48 hours, pull up the wire mesh and weigh the aluminum plate in advance (weight:
Cg) and leave in the fume hood for 4 hours. Thereafter, the entire aluminum plate is dried in a dryer at 105 ° C. for 3 hours, and the dry weight (weight: Dg) of the entire aluminum plate is measured.
The THF insoluble content is calculated by the following equation. THF-insoluble content (%) = (DCA) × 100 / B

[Evaluation Method of Coated Paper] The evaluation methods of the surface strength, the stiffness, the blocking resistance and the number of missing dots of the coated papers of the examples and comparative examples are as follows.

(Surface strength) Using a RI printing suitability tester (manufactured by Ishikawajima-Harima Heavy Industries, Ltd.), the coated paper was overprinted four times with picking ink (tack value: 12; manufactured by Toyo Ink Co., Ltd.). Is visually determined and indicated by a five-point method.
The higher the score, the better the surface strength.

(Stiffness) Clark Stiffness Meter (manufactured by Kumagai Riki Co., Ltd.)
Measure using M of paper at a test piece width of 30 mm
D, the critical length in the CD direction is obtained, and from their average value L,
Clark stiffness: Shimesuru in the value of ^{L 3/100 (cm 3/} 100). The higher the value, the higher the rigidity.

(Blocking resistance) The coating composition was applied to one side of a commercially available medium base paper having a basis weight of 48 g / m ² using a wire bar so that the coating amount after drying was 7 g / m ^2. After the work, it is dried in a hot air dryer at 100 ° C. for 10 seconds. After drying, the coated paper is taken out and allowed to stand for 5 hours in a constant temperature and humidity chamber adjusted to a temperature of 23 ° C. and a humidity of 65%, and then the coated paper is cut into a width of 3 cm and a length of 20 cm to obtain a test piece. . A polyethylene film having a width of 2.5 cm and a length of 25 cm was overlaid on the coated surface of the test piece, and was heated at 120 ° C. and 3 kg / cm ² using a heat sealer (manufactured by Tester Sangyo Co., Ltd.).
Under the conditions described above for 30 seconds. After crimping, it is taken out of the heat sealer and left at room temperature for 3 minutes while being crimped.
After standing for 3 minutes, the polyethylene film was peeled off from the test piece, and the amount of the adhered substance on the polyethylene film was visually determined and indicated by a 5-point method. Standard of 5-point method: 5 without adhesion
Points: 4 points with slight deposits, 3 points with deposits but few, 2 points with many deposits, and 1 point with extremely large deposits. The higher the score, the better the blocking resistance.

(Number of missing dots) Using a gravure printing suitability tester (Kumagaya Riki Kogyo Co., Ltd.)
Printing is performed on coated paper under the following conditions, and the number of missing dots in the 20% gradation portion is counted. As the ink used, xylene was added to OGH91 black ink (manufactured by Toyo Ink Co., Ltd.). Adjust for 3 seconds with 30 seconds. The printing pressure is 12kg /
cm ² and the printing speed is 70 m / min.

Reference Example 1: Copolymer latex (A)
(H) 50 parts of water were placed in a pressure-resistant vessel equipped with a stirrer, the inside of which was replaced with nitrogen.
0.5 parts of sodium bicarbonate, 0.2 parts of sodium lauryl sulfate, monomers shown in Table 1, and t-dodecylmercaptan were charged and stirred for 30 minutes to prepare a monomer emulsion. An autoclave equipped with a stirrer and a temperature sensor, and the inside of the autoclave was replaced with nitrogen, 0.05 parts of sodium ethylenediaminetetraacetate, 0.5 parts of potassium persulfate,
50 parts of water and sodium lauryl sulfate shown in Table 1 were charged, and the internal temperature was adjusted to 80 ° C. 8% of the monomer emulsion was added to an autoclave and reacted for 1 hour. The remaining monomer emulsion and 0.5 part of potassium persulfate were continuously added over 5 hours. After completion of the addition, the internal temperature was adjusted to 85 ° C., and this was maintained for 4 hours to complete the reaction. The polymerization conversion of each of the obtained copolymer latexes was 98% or more. A 20% aqueous solution of sodium hydroxide was added to each of the obtained copolymer latexes to adjust the pH to 8, and unreacted monomers were removed by a rotary evaporator. After further concentration, aggregates in the copolymer latex were removed using a 325 mesh wire mesh, and the solid content concentration was 50%, pH 8
Was obtained. Using each of the obtained copolymer latexes, the number average particle diameter, Tg, and THF insoluble content of the copolymer latex were measured and are shown in Table 1.

[0048]

[Table 1]

[Production of coated paper for gravure printing] Example 1 80 parts of clay (KCS: manufactured by ECCI) and delaminated clay (α-Plate: manufactured by ECCI) 2
0 parts, sodium polyacrylate 0.2 parts, sodium hydroxide 0.15 parts, starch (MS-4600: manufactured by Nippon Shokuhin Kako Co., Ltd.) 3 parts, copolymer latex (A) 6 parts, hollow polymer particles ( HP-1055: manufactured by Rohm & Haas Co., Ltd.), 5 parts of water and 76.2 parts of water were added, and the mixture was stirred for 30 minutes and the solid content concentration was 60
% Of the coating composition was obtained.

This coating composition was applied on a commercially available medium base paper having a basis weight of 48 g / m ² , and the coating amount after drying on one side was 7 g / m ^2.
The coating was performed using a table-top manual blade coater, and then dried in a hot air dryer at 100 ° C. for 10 seconds.
Further, the other side was coated and dried in the same manner as above to obtain a coated paper. The obtained coated paper was heated to a temperature of 23.
The sample was left standing for 5 hours in a constant temperature and humidity room adjusted to 65 ° C. and a humidity of 65%. The coated paper was treated with a metal roll at a surface temperature of 65 ° C and a linear pressure of 1
The surface treatment was performed twice using a laboratory mini super calender adjusted to 00 kg / cm to obtain a coated paper (1). The surface strength, rigidity, blocking resistance and number of missing dots of the coated paper (1) were measured. Table 2 shows the results.

Examples 2 to 4 Coated papers (2) to (4) in the same manner as in Example 1 except that copolymer latexes (B) to (D) were used instead of copolymer latex (A). I got The physical properties of the coated papers (2) to (4) were measured in the same manner as in Example 1. Table 2 shows the results.

Example 5 A coating composition having a solid content of 60% was prepared in the same manner as in Example 1 except that the amount of the hollow polymer particles was changed to 20 parts and the amount of water was further changed. Using this coating composition, a coated paper (5) was obtained in the same manner as in Example 1. The physical properties of the coated paper (5) were measured in the same manner as in Example 1. Table 2 shows the results.

Example 6 A coated paper (6) was obtained in the same manner as in Example 1, except that 4 parts of the copolymer latex (A) and 5 parts of starch were used. The physical properties of the coated paper (6) were measured in the same manner as in Example 1. Table 2 shows the results.

Example 7 A coated paper (7) was obtained in the same manner as in Example 1 except that 2 parts of the copolymer latex (A) and 7 parts of starch were used. The physical properties of the coated paper (7) were measured in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 1 Example 1 was repeated except that carboxymethylcellulose (Cellogen WSC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used instead of starch.
A coated paper (8) was obtained in the same manner as described above. The physical properties of the coated paper (8) were measured in the same manner as in Example 1. Table 2 shows the results.

Comparative Examples 2 to 5 Coated papers (9) to (12) in the same manner as in Example 1 except that copolymer latexes (E) to (H) were used instead of copolymer latex (A). I got Coated paper (9)-(1
Physical properties of 2) were measured in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 6 Coated paper (13) was obtained in the same manner as in Example 1, except that 8 parts of the copolymer latex (A) and 1 part of starch were used. The physical properties of the coated paper (13) were measured in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 7 A coated paper (14) was obtained in the same manner as in Example 1 except that the copolymer latex (A) was not used and the starch was 9 parts. The physical properties of the coated paper (14) were measured in the same manner as in Example 1. Table 2 shows the results.

[0059]

[Table 2]

From Table 2, it can be seen that the coated paper using carboxymethylcellulose instead of starch (Comparative Example 1) has extremely poor stiffness. Coated paper using a copolymer latex having a small number average particle diameter (Comparative Example 2)
Indicates that the rigidity is inferior and that the occurrence of missing dots is large. It can be seen that the coated paper using the copolymer latex having a large number average particle diameter (Comparative Example 3) has poor surface strength. It can be seen that the coated paper using the copolymer latex having a low Tg (Comparative Example 4) is inferior in surface strength, rigidity and blocking resistance. It can be seen that the coated paper using the copolymer latex having a high Tg (Comparative Example 5) had poor surface strength and generated many missing dots. Further, it can be seen that the coated paper (Comparative Example 6) using an adhesive having a high weight ratio of the copolymer latex has poor rigidity.
Coated paper using only starch as adhesive (Comparative Example 7)
Indicates that many missing dots are generated.

Compared with the coated papers of Comparative Examples 1 to 7, the coated paper for gravure printing of the present invention is excellent in white paper gloss, opacity, surface strength and blocking resistance, and has less occurrence of missing dots. I understand.

[0062]

EFFECT OF THE INVENTION By using the composition for coated paper for gravure printing of the present invention, it is possible to provide a coated paper for gravure printing excellent in surface strength, rigidity and anti-blocking property and generating few missing dots.

Preferred Embodiments of the Invention Embodiments of the present invention are summarized below. (1) An adhesive comprising a pigment, hollow polymer particles, a copolymer latex, and starch, the copolymer latex having a number average particle diameter of 0.06 to 0.2 μm, The glass transition temperature of the constituent copolymer is -5
0 to + 45 ° C., and the weight ratio of the copolymer latex / starch is 80/20 to 5/9 in terms of solid content.
5. A composition for coated paper for gravure printing, wherein the composition is 5. (2) The composition for coated paper for gravure printing according to (1), wherein the outer diameter of the hollow polymer particles is 0.3 to 10 μm, preferably 0.5 to 8 μm. (3) The porosity of the hollow polymer particles (the ratio of the internal void volume to the total particle volume) is 10% or more, and preferably 30% or more.
% Or more, the composition for coated paper for gravure printing according to (1) or (2). (4) The amount of the hollow polymer particles used is 0.1 to 30% by weight, preferably 0.5 to 25% by weight, more preferably 1 to 20% by weight based on 100 parts by weight of the pigment. ~
The composition for coated paper for gravure printing according to any one of (3).

(5) The copolymer latex according to any one of (1) to (4), wherein the number average particle diameter is preferably 0.07 to 0.18 μm, more preferably 0.08 to 0.15 μm. The composition for coated paper for gravure printing according to the above. (6) The glass transition temperature of the copolymer is preferably -50
The composition for coated paper for gravure printing according to any one of (1) to (5), which has a temperature of from −40 ° C. to + 40 ° C., and more preferably from −50 to + 35 ° C. (7) The amount of the copolymer insoluble in tetrahydrofuran is 1
The composition for coated paper for gravure printing according to any one of (1) to (6), which is 0 to 95% by weight, preferably 20 to 90% by weight, and more preferably 30 to 85% by weight. (8) The composition for coated paper for gravure printing according to any one of (1) to (7), wherein the copolymer is a styrene-butadiene copolymer or a carboxy-modified styrene-butadiene copolymer. (9) The gravure printing according to any one of (1) to (8), wherein the starch comprises at least one selected from oxidized starch, etherified starch, esterified starch, and enzyme-modified starch. Composition for coated paper.

(10) The weight ratio of the copolymer latex to starch is preferably 75/25 to 10 in terms of solid content.
/ 90, more preferably 70/30 to 15/85, the composition for coated paper for gravure printing according to any one of (1) to (8). (11) The amount of the adhesive used is 2 to 30 parts by weight, preferably 3 to 2 parts by weight, in terms of solid content, based on 100 parts by weight of the pigment.
5 parts by weight, more preferably 3 to 20 parts by weight (1)
The composition for coated paper for gravure printing according to any one of (9) to (9).

(12) Coated paper for gravure printing obtained by applying the composition of (1) to (9) to base paper. (13) The coated paper for gravure printing according to (12), wherein the basis weight of the base paper is 20 to 200 g / m ² , preferably 30 to 160 g / m ² . (14) The base paper is coated with the composition of (1) to (9) in an amount of 3
-20 g / m ² (dry weight) (1
The coated paper for gravure printing according to 2) or (13).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L055 AG27 AG47 AG56 AG63 AG70 AG71 AG72 AG76 AG89 AG94 AG97 AH02 AH37 AJ04 EA16 EA20 EA32 FA11 FA12 FA13 FA15 GA19

Claims (2)

[Claims] 1. An adhesive comprising a pigment, a hollow polymer particle, a copolymer latex and a starch, wherein the copolymer latex has a number average particle size of 0.06 to 0.2 μm,
The copolymer constituting the copolymer latex has a glass transition temperature of −50 to + 45 ° C., and the weight ratio of the copolymer latex / starch is 80/2 in terms of solid content.
A composition for coated paper for gravure printing, wherein the composition is 0 to 5/95. 2. A coated paper for gravure printing obtained by coating the composition according to claim 1 on a base paper.