JPH1046490A - Composition for coated paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition for a coated paper excellent in printability, surface strength, internal strength, water resistance (sizing properties), etc., in producing a coated paper, especially a fine coated paper or a surface-coated paper. SOLUTION: This composition for a coated paper comprises an aqueous polymer composition obtained by mixing (A) a copolymer latex prepared by subjecting 100 pts.wt. of a polymerizable monomer mixture comprising 0-60 pts.wt. of an aliphatic conjugated diene-based monomer, 0.5-10 pts.wt. of an ethylenic unsaturated monomer and 30-99.5 pts.wt. of another copolymerizable monomer to emulsion polymerization with (B) a water-soluble polymer containing >=60wt.% of acrylamide in the weight ratio of solid content of the components A/B or 20/80 to 99/1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylamide-based polymer, which is one of typical water-soluble polymers as paper and pulp chemicals such as an internal paper strength enhancer or a surface coating agent, and a paper coating agent. When the aqueous polymer composition is used for the production of coated paper, especially lightly coated paper or surface coated paper by mixing a binder, a plastic pigment, and a copolymer latex (polymer fine particles) used as a pigment binder. The present invention provides a coated paper composition having excellent water resistance (size), surface strength, internal strength, printability and the like.

[0002]

2. Description of the Related Art In recent years, the usage ratio of used paper has been increasing in the papermaking industry for environmental protection. Recovered paper contains fine fibers and therefore has weak bonding between pulp and low paper strength. Therefore, a surface coating agent is used in addition to the internal paper strength agent, and the amount thereof is also increasing. Surface coating agents are used for corrugated cardboard exterior liners and other paperboard, high-quality paper, medium-quality paper, coated base paper, newsprint, etc., and modify surface properties, specifically, surface friction, fluff, lubricity , Moisture absorption, gloss, paper powder, picking during printing, internal paper strength, water resistance (size)
It is used for the purpose of improvement. Conventionally used surface coating agents include acrylamide polymers, starch and modified products thereof, cellulose derivatives such as carboxymethyl cellulose, and water-soluble polymers such as polyvinyl alcohol and derivatives thereof. It is difficult to obtain sufficient surface strength with a coating agent,
No improvement in water resistance (size) can be expected. In order to overcome these problems by increasing the amount of coating, new problems such as a decrease in ink set and occurrence of blocking occur. Further, in recent years, for example, in newsprint applications, the weight of the base paper has been reduced, and the surface strength, internal strength, printability, and water resistance (size) of the paper have been increased by increasing the speed of printing and increasing the ratio of offset rotary printing. Problems such as improvement have become apparent. For example, in the field of information recording paper such as ink jet recording paper, the use of special paper and common paper has been promoted, and a slight amount of coating processing (fine coating) has been performed.
There is an increasing demand for imparting sufficient printability and water resistance (size).

[0003]

SUMMARY OF THE INVENTION Under the above background, the present invention relates to the use of the aqueous polymer composition in the production of coated paper, especially lightly coated paper or surface coated paper. An object of the present invention is to provide a coated paper composition having excellent printability, surface strength, internal strength, and water resistance (size).

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that an aqueous polymer composition obtained by mixing polymer particles and a water-soluble polymer containing acrylamide as a main component at a specific ratio is used. The present invention has been completed. The composition for coated paper in the present invention contains an aqueous polymer composition obtained by mixing polymer fine particles, that is, a copolymer latex prepared by emulsion polymerization and a water-soluble polymer containing acrylamide as a main component. It is a feature.

That is, the present invention relates to (1) 0-60 parts by weight of an aliphatic conjugated diene monomer, 0.5-10 parts by weight of an ethylenically unsaturated acid monomer, and other copolymerizable monomers. 3
0-99.5 parts by weight of polymerizable monomer mixture 100
(A) / (B) = a copolymer latex (A) obtained by emulsion polymerization of parts by weight and a water-soluble polymer (B) containing 60% by weight or more of acrylamide at a solid content weight ratio.
A coated paper composition comprising an aqueous polymer composition mixed in a ratio of 20 / 80-99 / 1,
Is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The copolymer latex (A) of the present invention will be described.
The copolymer latex of the present invention contains 0 to 60 parts by weight of an aliphatic conjugated diene monomer and 0.5 to 0.5 parts of an ethylenically unsaturated acid monomer.
-10 parts by weight, other copolymerizable monomer 30-9
It is obtained by emulsion polymerization of 100 parts by weight of a monomer mixture consisting of 9.5 parts by weight.

Specific examples of the aliphatic conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene,
2-chloro-1,3-butadiene and the like can be mentioned. These monomers can be used alone or in combination of two or more kinds, and the used amount is 0 to 60 parts. If the amount is more than the above range, the water resistance, whiteness and opacity tend to decrease when used as a composition for coated paper.

Specific examples of the ethylenically unsaturated acid monomer include monocarboxylic acids such as acrylic acid and methacrylic acid;
Dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; further, half esters such as methyl maleate and methyl itaconate; and sulfonic acids such as styrene sulfonic acid, 2-sulfoethyl acrylate, and acrylamidopropane sulfonic acid. Can be. Also, anhydrides of dicarboxylic acids can be used. These monomers can be used alone or in combination of two or more. Their usage is 0.5-10 parts. If the amount is less than the above range, the adhesive strength and stability tend to decrease when used as a composition for coated paper. On the other hand, if it is more than the above range, the viscosity may increase, and the operability may decrease.

Specific examples of other monomers include aromatic vinyl compounds such as styrene, vinyltoluene and p-methylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycidyl (meth)
Ester compounds of acrylic acid or methacrylic acid such as acrylate; dialkyl esters of ethylenically unsaturated carboxylic acids such as diethyl fumarate and dimethyl itaconate; vinyl cyanide compounds such as acrylonitrile, methacrylonitrile and α-chloroacrylonitrile; ) Ethylenically unsaturated carboxylic amides such as acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide and N-substituted compounds thereof, methylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate , Methylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dibutylaminoethyl (meth)
Examples include ethylenically unsaturated monomers such as ethylenically unsaturated amine compounds such as acrylate, dimethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, 2-vinylpyridine, and 4-vinylpyridine. These monomers can be used alone or in combination of two or more. Their usage is 30-99.5 parts. If the amount is less than the above range, the water resistance, whiteness and opacity tend to decrease when used as a composition for coated paper.

The surfactant (emulsifier) used in the present invention is not particularly limited, and nonionic, anionic, amphoteric and polymerizable surfactants can be used. Specifically, for example, a sulfate salt of a higher alcohol such as sodium dodecyl sulfate, a sulfonate-type anionic interface such as sodium (di) alkyldiphenyl ether (di) sulfonate, sodium dodecylbenzenesulfonate, sodium dioctylsulfosuccinate and the like. Surfactants, nonionic surfactants of the type such as alkyl esters of polyethylene glycol, alkyl phenol ethers, alkyl ethers and the like can be used. Examples of the amphoteric surfactant include those having a carboxylate, a phosphate, or a phosphate as an anion portion and an amine salt or a quaternary ammonium salt as a cation portion. Specifically, betaine type,
Glycine-type amphoteric surfactants and the like can be mentioned. Specific examples of the polymerizable surfactant include propenyl-2.
Anionic polymerizable surfactants such as -ethylhexyl sulfosuccinate sodium salt, (meth) acrylic acid polyoxyethylene sulfate, polyoxyalkylpropenyl ether sulfate ammonium salt, (meth) acrylic acid polyoxyethylene ester phosphate, etc. And nonionic polymerizable surfactants such as polyoxyethylene alkyl benzene ether (meth) acrylate and polyoxyethylene alkyl ether (meth) acrylate. These may be used alone or in combination of two or more.

In the present invention, as a polymerization initiator, a redox-based initiator such as a water-soluble initiator such as potassium persulfate, ammonium persulfate, or sodium persulfate alone or in combination with a reducing agent such as sodium bisulfite, amines or the like is used. It can also be used as a polymerization initiator. Further, oil-soluble initiators such as a water-soluble azo initiator, benzoyl peroxide and azobisisobutyronitrile can also be used.

In the present invention, known molecular weight regulators used in general emulsion polymerization can be used as the molecular weight regulator. Specifically, for example, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan, mercaptans such as t-tetradecyl mercaptan, dimethyl xanthogen disulfide, diethyl xanthogen disulfide, Xanthogen disulfides such as diisopropylxanthogen disulfide, thiuram disulfides such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, terpenoids such as terpinolene, α-methylstyrene dimer, 2-ethylhexyl thioglycolate, 3-phenyl -1-pentene, 1,4-cyclohexadiene, hydroquinone,
t-butylcatechol, 2,6-di-t-butyl-4-
In addition to methylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-xylenol, allyl compounds such as allylamine and allyl alcohol, mercaptans such as mercaptoethanol, mercaptopropionic acid and thioglycolic acid, and cysteamine. Can be mentioned.

The acrylamide-based water-soluble polymer (B) of the present invention will be described. Examples of monomers that can be used by copolymerizing with the acrylamide monomer include ionic, hydrophilic, and hydrophobic monomers, and among the ionic monomers, as the anionic monomer, (Meta)
Monocarboxylic acids such as acrylic acid and crotonic acid and salts thereof, dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid, half esters and salts thereof, 3-butene 1,2,3-tricarboxylic acid, Tricarboxylic acids such as pentene-1,2,4-tricarboxylic acid and aconitic acid and salts thereof, vinylsulfonic acid, styrenesulfonic acid, 2-sulfoethylacrylate, acrylamidepropanesulfonic acid, acrylamide-te
Examples include sulfonic acid group-containing unsaturated monomers such as rt-butyl sulfonic acid and salts thereof. Among the ionic monomers, cationic monomers include N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and N, N-dimethylaminopropyl (meth) acrylamide , N, N-diethylaminopropyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylate, N, N −
Third such as diethylaminopropyl (meth) acrylate
And quaternary amino group-containing unsaturated monomers obtained by reacting these with quaternizing agents such as methyl chloride, dimethyl sulfate and benzyl chloride.

Examples of hydrophilic monomers include methacrylamide, N-methylol (meth) acrylamide, acetone acrylamide, N, N-dimethyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-
Diethyl (meth) acrylamide, N-propylacrylamide, N-acryloylpyrrolidine, N-acryloylpiperidine, N-acryloylmorpholine, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, various methoxypolyethylene glycol (meth) acrylates , N-vinyl-2-pyrrolidone and the like.

The hydrophobic monomers include N, N-di-n
-Propyl (meth) acrylamide, Nn-butyl (meth) acrylamide, Nn-hexyl (meth) acrylamide, Nn-octyl (meth) acrylamide, N-tert-octyl (meth) acrylamide,
N-alkyl (meth) acrylamide derivatives such as N-dodecylacrylamide, Nn-dodecylacrylamide, N, N-diglycidyl (meth) acrylamide, N
N- (ω-glycidoxyalkyl) such as-(4-glycidoxybutyl) (meth) acrylamide, N- (5-glycidoxypentyl) acrylamide, N- (6-glycidoxyhexyl) acrylamide Meth) acrylamide derivatives, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
(Meth) acrylate derivatives such as dodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and glycidyl (meth) acrylate; olefins such as vinyl acetate, vinyl chloride, vinylidene chloride, ethylene, propylene, and butene; acrylonitrile and methacryloyl Ethylene nitrile compounds such as nitrile, styrene, α-
Methylstyrene, butadiene, isoprene and the like can be mentioned. These monomer components can be used alone or in combination of two or more, but the total amount used is preferably less than 40% by weight of the water-soluble polymer component. In some cases, a problem may occur in polymerization stability.

Examples of monomers which can be used by copolymerizing with the acrylamide monomer in addition to the above compounds include crosslinkable vinyl monomers. Specific examples include bifunctional types such as methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and divinylbenzene. A crosslinkable monomer, or
Examples include polyfunctional crosslinkable monomers such as 1,3,5-triacryloylhexahydro-S-triazine, triallyl isocyanurate, and pentaerythritol triacrylate. The amount of these crosslinkable vinyl monomers used is 5% by weight or less based on the total amount of all the monomers constituting the water-soluble polymer containing acrylamide as a main component. It is preferable that the content be not more than weight%.
In addition, it is possible to use glyoxal monourenes such as monomethylol glyoxal monourene, dimethylol glyoxal monourene, monomethyl glyoxal monourene, dimethyl glyoxal monourene, and monomethylol monomethyl glyoxal monourene for the purpose of improving water resistance. (Japanese Patent Laid-Open No. 6-3)
41095). These may be used in an amount of 0.1 to 100 parts of a water-soluble polymer containing acrylamide as a main component.
1-10 parts.

The method for polymerizing the water-soluble polymer containing acrylamide as the main component of the present invention is in accordance with a known method for polymerizing a water-soluble polymer, but radical polymerization is preferred. The production method may be either batch polymerization in which all the monomers are charged into a reaction vessel at a time and polymerization, or semi-batch polymerization in which a part of the monomers are continuously added during the polymerization.

The polymerization initiator used in the present invention is not particularly limited, but is preferably a water-soluble initiator. The monomers may be added all at once to the reaction vessel charged, or may be continuously dropped. Specific examples of the initiator include persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate; and peroxides such as hydrogen peroxide, benzoyl peroxide, and di-tert-butyl peroxide. These initiators can be used alone or as a redox-based polymerization initiator in combination with a reducing agent. Examples of the reducing agent in this case include salts of lower ionization such as sulfite, bisulfite, iron, copper, and cobalt; organic amines such as N, N, N ', N'-tetramethylethylenediamine; and aldose. And reducing sugars such as ketose. Also, azo compounds are preferred initiators, and 2,2′-azobis-2-methylpropionamidine hydrochloride, 2,2′-azobis-2,4-dimethylvaleronitrile, 2,2′-azobis-N, N '
-Dimethyleneisobutylamidine hydrochloride, 2,2'-azobis-2-methyl-N- (2-hydroxyethyl)-
Propionamide, 2,2′-azobis-2- (2-imidazolin-2-yl) -propane and salts thereof,
4'-azobis-4-cyanovaleric acid and its salts can be used. It is also possible to use two kinds of the above-mentioned polymerization initiators in combination.

There is no particular limitation on the chain transfer agent used in the present invention, but a water-soluble chain transfer agent is preferred. Specific examples include allylsulfonic acid, methallylsulfonic acid and their sodium or potassium salts. Examples thereof include alkali metal salts or ammonium salts, allyl compounds such as allylamine and allyl alcohol, mercaptans such as mercaptoethanol, mercaptopropionic acid and thioglycolic acid, and cysteamine.

The viscosity of the water-soluble polymer containing acrylamide as a main component of the present invention is 50
It is 0 poise or less, preferably 100 poise or less. If the viscosity is more than the above range, there arises a problem that workability is deteriorated and stability at the time of mixing with the copolymer latex is lowered.

The aqueous polymer composition of the present invention can be used as it is as a composition for coated paper, or can be used by further blending a pigment or the like. When a pigment is not used, for example, when used as a surface coating agent, the aqueous polymer composition may be used alone or with various chemicals, for example, a sizing agent such as a rosin-based or synthetic system, a water-proofing agent, and a release agent. , An antifoaming agent, a rust inhibitor and the like.
When using a pigment in the composition for coated paper, as the pigment to be used, clay used for ordinary coated paper, light calcium carbonate, heavy calcium carbonate, titanium oxide, aluminum hydroxide, satin white, barium sulfate, Inorganic pigments such as magnesium oxide, talc, and colloidal silica, and organic pigments such as polystyrene, SBR, and phenolic resin can be used alone or in combination of two or more. In addition, dispersants, water-proofing agents, viscosity modifiers, Antifoaming agent, water retention agent, dye, fluorescent dye, solvent, pH adjuster, surfactant,
Preservatives, other auxiliaries, additives and the like can be used as needed.

The composition for coated paper thus obtained is applied by a coating apparatus such as a blade coater, a bar coater, a gate roll coater, a size press, a calender and a spray. As the coated base paper of the present invention, newspaper base paper, medium paper, high quality paper, and paperboard having a basis weight of 40 to 300 g / m 2 are used. The coating amount of the composition for coated paper on these base papers is 0.1-25 g / m 2 on one side in a dry state. The coated paper is finished by various methods such as a calender.

[0023]

The present invention will now be described more specifically with reference to examples. In the examples, “%” and “parts” are based on weight. Production Example 1 of Copolymer Latex In an autoclave equipped with a stirrer, 100 parts of deionized water was charged and adjusted to 65 ° C. while purging with nitrogen, and then 0.5 parts of sodium dodecylbenzenesulfonate and 1.8 parts of potassium persulfate were added. Is added. To this aqueous solution, 34 parts of butadiene emulsified using a homogenizer and styrene 60 were added.
Parts, a total of 100 parts by weight of a monomer mixture of 1 part by weight of acrylic acid, 2 parts of itaconic acid, and 3 parts of methacrylamide.
0.6 parts of dodecyl mercaptan, 2,4-dimethyl-6
-T-butylphenol (trade name: Anti-Oxid
ant No. 30 / E. I. DU PONT NEM
OURS & Co. (Inc., INC) 1.2 parts, an emulsion consisting of 0.3 parts of sodium dodecylbenzenesulfonate and 50 parts of deionized water was added continuously for 6 hours, and then the polymerization was continued for another 8 hours to complete the polymerization. The polymerization was completed at a polymerization conversion of 98%. Then, the obtained polymer fine particle dispersion is p-pulped using sodium hydroxide.
After adjusting to H6, steam was blown in to remove unreacted monomers, and the solid content was reduced to 50 by heating under reduced pressure.
%, An average particle diameter of 105 nm, and a copolymer fraction (51) having a gel fraction of 51%.

Here, the particle diameter and the gel fraction were measured by the following methods. (A) Average particle size The copolymer latex was diluted with pure water to a predetermined concentration, and then measured with a submicron particle size analyzer manufactured by Coulter Electronics. (B) Gel content The copolymer latex is uniformly cast on a polypropylene plate, left to dry at room temperature for one week, and then dried in a hot air circulating drier at 80 ° C for one hour to form a film. After accurately weighing about 1 g with an analytical balance and immersing it in 100 ml of toluene for 2 days, 10 ml of a toluene solution is collected, and the solid content after drying is weighed, and the gel content is calculated by the following method.

[0025] Production Example 2 of Copolymer Latex Copolymer latex having a particle diameter of 107 nm and a gel fraction of 81% was prepared in the same manner as in Production Example 1 of the copolymer latex except that tert-dodecyl mercaptan was not used. 2) was obtained.

Production Example 3 of Copolymer Latex The amount of styrene and butadiene was 84 parts and 10 parts, respectively.
A copolymer latex (3) having a particle diameter of 103 nm and a gel fraction of 35% was obtained in the same manner as in Production Example 1 of the copolymer latex, except for using parts.

Production Example 1 of Water-Soluble Polymer Containing Acrylamide as Main Component 80.71 parts of deionized water was placed in a five-necked flask equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen gas inlet pipe, and a dropping port.
90 parts of a 50% aqueous acrylamide solution and 6.25 parts of an 80% aqueous acrylic acid solution were charged, and the temperature of the aqueous solution was adjusted to 30 ° C. while blowing nitrogen gas. To this aqueous solution, 0.28 parts of ammonium persulfate was added as an initiator in deionized water 3
To 6.52 parts, 0.13 part of sodium bisulfite as a reducing agent of a redox initiator was dissolved in 35.52 parts of deionized water, respectively, and then added to start the reaction. 60
Polymerization for minutes, without controlling the temperature of the aqueous solution during that time,
Spontaneous fever was caused. The reaction was terminated by cooling, and a 20% water-soluble polymer (1) having a Brookfield type B viscosity of 30 ps at 25 ° C. was obtained.

Preparation Example 1-3 of Aqueous Polymer Composition To 500 g of the copolymer latex (1) having a solid content adjusted to 20%, 50 g and 100 g of 20% of the water-soluble polymer (1) were stirred, respectively. Or 200 g was added to prepare aqueous polymer compositions (1), (2) and (3).

Production Example 4 of Aqueous Polymer Composition To 500 g of a copolymer latex (2) having a solid content adjusted to 20%, 100 g of 20% of a water-soluble polymer (1) was added with stirring to obtain an aqueous polymer composition. Polymer composition (4) was prepared.

Production Example 5 of Aqueous Polymer Composition To 500 g of a copolymer latex (3) having a solid content adjusted to 20%, 100 g of 20% of a water-soluble polymer (1) was added with stirring to obtain an aqueous polymer composition. A polymer composition (5) was prepared.

Example 1 The aqueous polymer composition (1) shown in the production example was used at a solid content of 5%.
And adjusted with deionized water. Next, using a blade coater, the basis weight 44 adjusted to 28 cm long and 18 cm wide was used.
By adjusting the blade pressure of a blade coater on a g / m2 base paper, 0.5 g / m2 of a dry coating amount (hereinafter simply referred to as coating amount) was applied to one surface. 70 ℃ after coating
Was dried in a drum dryer for 50 seconds to obtain a coated paper.
The coated paper is kept at a constant temperature and humidity (temperature 20 ° C, humidity 65%).
After seasoning for 4 hours, the following physical properties were evaluated, and the results are shown in Table 1. (1) Blank glossiness Using a gloss meter GM-3D manufactured by Murakami Color Co., Ltd., an angle of 75
The specular gloss of ゜ was measured. (2) Printing gloss Using an RI printing suitability tester (manufactured by Mei Seisakusho), printing with ink (Toyo Ink Mark Five New Indigo)
After seasoning at constant temperature and humidity (temperature 20 ° C, humidity 65%) for a period of time, use a gloss meter GM-3D manufactured by Murakami Color Co., Ltd.
The specular gloss at an angle of 60 ° was measured. (3) Dry pick strength Using an RI printing suitability tester (manufactured by Mei Seisakusho), printing with ink (Toyo Ink SMX Tack 25) was used to visually determine the peeling state, and the 5-point method (5 points was excellent, One point was evaluated as poor). (4) Wet pick strength Using a RI printing suitability tester (manufactured by Akira Seisakusho), wet the paper surface with a Molton roll, immediately print with ink (Toyo Ink SMX Tack 25), and visually check the peeling state. The evaluation was made according to a 5-point method (5 points excellent, 1 point poor).

(5) Ink acceptability test Using an RI print suitability tester (manufactured by Meiji Seisakusho), wet the paper surface with a Molton roll, immediately print with ink (Toyo Ink SMX Tack 25), and accept the ink. Concentration 5
Evaluation was made by the point method (5 points excellent, 1 point poor). (6) Ink setting test Using an RI printing suitability tester (manufactured by Mei Seisakusho), printing was performed every 10 seconds with ink (Toyo Ink Mark Five New Indigo), and ink density was transferred by pressing art paper on the printing surface. For 24 hours at a constant temperature and humidity (temperature of 20 ° C., humidity of 65%), and then measured with a Macbeth ink densitometer (Sakata Inx Co., Ltd.). (7) Stiffness test A coated paper sample was adjusted to 5 cm in length and 2.5 cm in width, and a Gurley stiffness tester (Kumaya Riki Kogyo Co., Ltd.)
Was used for the measurement. (8) Break length measurement test Adjust the coated paper sample to 15 cm long and 1.5 cm wide,
The measurement was performed using a digital tensile tester (manufactured by Sagawa Seisakusho). (9) Size test A test was conducted by a water drop method. After 1 μl of deionized water was dropped on the coated paper, the time until the water droplet on the surface of the coated paper disappeared was measured and expressed in seconds.

Example 2-4 The aqueous polymer composition (2) shown in Production Example was used to obtain a solid content of 2
%, 5%, and 10%, respectively, by diluting with deionized water. Next, using a blade coater, length 28 cm, width 1
By adjusting the solid content of the aqueous polymer composition and the blade pressure of the blade coater on a base paper having a basis weight of 44 g / m 2 adjusted to 8 cm, the coating amount was 0.2, 0.5, 1.5 g.
/ M <2> on one side. Hereinafter, physical properties were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Examples 5-7 Physical properties were evaluated in the same manner as in Example 1 except that the aqueous polymer compositions (3) to (5) shown in Production Examples were used. The results are shown in Table 1. .

Comparative Example 1 The above physical properties were evaluated using base paper having a basis weight of 44 g / m 2, and the results are shown in Table 1. Comparative Example 2-4 Except that the water-soluble polymer (1) shown in Production Example was used,
Physical properties were evaluated in the same manner as in Example 2-4, and the results are shown in Table 1.

[0036]

[Table 1]

[0037]

According to the present invention, there is provided an acrylamide polymer which is one of typical water-soluble polymers as paper and pulp chemicals such as an internal paper strength enhancer or a surface coating agent, and a binder for paper coating. Plastic pigment, by mixing a copolymer latex used as a pigment binder, coated paper, especially when using the water-soluble polymer in the production of finely coated paper or surface coated paper, printability, surface strength, Provided is a coated paper composition having excellent internal strength, water resistance (size), and the like.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Goro Kuwamura 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Saburo Hayano 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical (72) Inventor Kenichi Nakane 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. An aliphatic conjugated diene monomer 0-60 parts by weight An ethylenically unsaturated acid monomer 0.5-10 parts by weight Other copolymerizable monomers 30-99.5 parts by weight A copolymer latex (A) obtained by emulsion polymerization of 100 parts by weight of a polymerizable monomer mixture and a water-soluble polymer (B) containing 60% by weight or more of acrylamide are represented by a solid content weight ratio of (A) / ( B) = A coated paper composition comprising an aqueous polymer composition mixed at a ratio of 20 / 80-99 / 1.