JPH08158296A - Paper-coating liquid composition - Google Patents

Abstract

PURPOSE: To provide paper-coating liquid composition which has excellent high- speed coating fluidity and moisture retention and gives coated paper having excellent white paper feeling and gravure printability. CONSTITUTION: This paper-coating composition comprises (A) 100 pts.wt. of pigment, (B) 4-20 pts.wt. of a diene copolymer latex of 0.06-0.16μm average particle size, resulting from emulsion polymerization of a monomer mixture of (a) 20-70wt.% of a conjugated diene monomer, (b) 0.5-10wt.% of an ethylenically unsaturated carboxylic acid, and (c) 20-79.5wt.% of other copolymerizable monomers, and (C) 0.1-1 pt.wt. of an alkali-soluble latex, resulting from emulsion polymerization of a monomer mixture of (d) 20-50wt.% of an ethylenically unsaturated monocarboxylic acid, (e) 20-75wt.% of an alkyl acrylate and (f) 5-30wt.% of vinyl acetate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper coating liquid composition having excellent fluidity and water retention suitable for high-speed coating, and having excellent white surface feeling of coated paper and excellent gravure printing suitability. Is.

[0002]

2. Description of the Related Art Coated papers are pigments such as kaolin clay, calcium carbonate, satin white, talc and titanium oxide on the surface of base paper for the purpose of improving printability and optical properties such as gloss. Copolymer latex as a binder and a coating liquid containing a water-retaining agent or a water-soluble polymer such as starch, casein, polyvinyl alcohol, or carboxymethyl cellulose as a main binder as a main constituent are applied. The copolymer latex contains styrene and butadiene as main monomer components, and is emulsion-polymerized to obtain a styrene-butadiene copolymer latex, so-called SB.
Latex is commonly used.

In recent years, with the increase in the production amount of coated paper, high-speed coating has been promoted for the purpose of improving the production capacity. Further, a high solidification of the coating liquid is being promoted for the purpose of coping with the decrease in the drying ability due to the high speed coating and improving the production efficiency. The coating liquid is required to have high performance required to withstand such high speed coating and high solid content coating. For example, in high-speed coating with blade coating or high solids coating, the coating liquid is required to have excellent high-speed fluidity and water retention, but if these are inferior, deposits grow on the blade tip. (Bleeding) This will lead to troubles such as the adherence of lees on the coated paper, the generation of aggregates and the formation of streaks on the coated paper (streak).

On the other hand, with the speeding up of the coating process, there is a problem in the quality of coated paper. For example, it is a slight unevenness in the glossiness of coated paper (white paper surface feeling), deterioration of printability in gravure printing (halftone dot reproducibility), and the like. These are important problems because they lower the commercial value of coated paper. SB latex, which is the main binder of coated paper, is required to be improved so as to reduce such problems caused by high speed coating. It is generally known that a method of reducing the particle size of the copolymer latex is effective for improving the high-speed fluidity of the coating liquid, and is disclosed in, for example, JP-A-5-32710.
And JP-A-5-32711 describes a method for producing a copolymer latex having a small particle size by using a fine particle seed. However, the paper coating composition using a latex having a particle size of 0.1 to 0.18 μm, which is exemplified in the publication, is excellent in high-speed fluidity, but satisfies the quality of coated paper, particularly the feeling of white paper. It is difficult to improve it to the level possible.

Further, as a method for improving the dot reproducibility of coated paper, Japanese Patent Publication No. 22088/1990 and Japanese Patent Publication No.
No. 24280 describes a composition for paper coating using an alkali-soluble latex. However, the paper coating liquid composition exemplified here is certainly excellent in halftone dot reproducibility and although the gravure suitability is improved, the white surface feeling of the coated paper does not reach a satisfactory level, and further High-speed fluidity is also insufficient.

As described above, further improvement is required for the high-speed coating property of the coating liquid and the coated paper quality, particularly the white paper surface feeling and halftone dot reproducibility.

[0007]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a paper coating liquid which is excellent in high-speed coating fluidity and water retention of the coating liquid, and which has good white surface feeling of coated paper and good gravure printing suitability. It is intended to provide a composition.

[0008]

[Means for Solving the Problems] The inventors of the present invention used a diene copolymer latex having a particle size of 0.06 to 0.16 μm and an alkali-soluble latex having a specific composition in combination to rapidly flow a coating solution. Based on this finding, the present invention was accomplished based on the finding that the properties, water retention, and whiteness of coated paper are dramatically improved.

That is, in the present invention, 4 to 4 parts by weight of the following diene copolymer latex (A) is added to 100 parts by weight of the pigment.
20 parts by weight of 0.1% alkali-soluble latex (B)
The present invention provides a paper coating liquid composition characterized by containing 1 to 1 part by weight. Diene copolymer latex (A): (a) 20 to 70% by weight of conjugated diene monomer, (b) 0.5 to 10% by weight of ethylenically unsaturated carboxylic acid monomer, (c) other A particle size of 0.0, which is obtained by emulsion polymerization of a monomer mixture composed of 20 to 79.5% by weight of a copolymerizable vinyl monomer.
Diene-based copolymer latex of 6 to 0.16 μm. Alkali-soluble latex (B): (d) 20 to 50% by weight of ethylenically unsaturated monocarboxylic acid monomer, (e) 20 to 75% by weight of alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, (F) Vinyl acetate 5-30
An alkali-soluble latex obtained by emulsion polymerization of a monomer mixture consisting of wt%.

Hereinafter, the present invention will be described in detail. Examples of the (a) conjugated diene monomer used for producing the diene copolymer latex (A) include butadiene, isoprene, and 2-chloro-1,3-butadiene. These conjugated diene-based monomers may be used alone or in combination of two or more, and the amount used is 20 to
70% by weight, preferably 25 to 60% by weight in terms of cohesive strength. If the amount used is less than 20% by weight, the resulting polymer will be too brittle, and if it exceeds 70% by weight, it will be too soft, and in either case, the strength will be insufficient.

Examples of the (b) ethylenically unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and crotonic acid. These carboxylic acids may be used either individually or in combination of two or more, and the amount used is selected in the range of 0.5 to 10% by weight, preferably 1 to 7% by weight. If this amount is less than 0.5% by weight, the dispersion stability of the latex is not sufficient, various problems occur during coating solution preparation and coating, and the strength is insufficient. If it exceeds 10% by weight, the viscosity of the latex or the coating solution becomes too high, which is not preferable.

(C) Other copolymerizable vinyl monomers include aromatic vinyl monomers such as α-methylstyrene, vinyltoluene and P-methylstyrene, acrylonitrile, methacrylonitrile and α-. Vinyl cyanide monomers such as chloracrylonitrile, acrylamide,
Methacrylamide, N-methylolacrylamide, N
N-monoalkyl (meth) acrylamides such as -methylacrylamide and N-methylmethacrylamide, N,
Amide group-containing ethylene monomers such as N, N-dialkyl (meth) acrylamide, glycidyl methacrylamide, N-dimethylacrylamide, N, N-dimethylmethacrylamide, etc., methyl acrylate, ethyl acrylate, butyl acrylate , Methyl methacrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, glycidyl methacrylate, alkyl esters of acrylic acid or methacrylic acid, carboxylic acid vinyl esters such as vinyl acetate, vinyl halides such as vinyl chloride Examples thereof include ethylenic amines such as aminoethyl acrylate and dimethylaminoethyl acrylate, sodium styrenesulfonate, and the like.

These copolymerizable monomers may be used alone or in combination of two or more. Also, the amount used is 20-
It is selected in the range of 79.5% by weight, preferably 15 to 70% by weight. If the amount used exceeds 79.5% by weight, the pick strength of the coated paper becomes poor, which is not preferable. The particle size of the diene copolymer latex (A) is 0.06 to 0.16 μm.
m, preferably 0.08 to 0.14 μm. If it is less than 0.06 μm, the viscosity of the latex becomes too high, which hinders its use. On the other hand, 0.16
When it exceeds μm, the high-speed fluidity of the coating liquid is lowered and the effect of the present invention is not exhibited.

The latex particle size can be controlled within this range by a known method. For example, in seed polymerization, the particle size of the seed latex used or the amount used may be adjusted. In addition, in a polymerization method that does not use seeds, conditions such as the type of emulsifier, the amount of emulsifier, the amount of polymerization initiator, and the polymerization temperature may be set appropriately. Generally, the larger the amount of emulsifier and the amount of polymerization initiator, the smaller the particle size of the latex obtained. Further, if these conditions are the same, the particle size of the latex obtained becomes smaller as the polymerization temperature becomes higher.

Next, the alkali-soluble latex (B) will be described. The alkali-soluble latex (B) is
A non-crosslinkable copolymer which is completely soluble in an alkaline aqueous solution is preferable. The complete dissolution with an alkaline aqueous solution here means that the pH of the latex is adjusted to 7.5 by dropping a 3% by weight aqueous solution of sodium hydroxide into a latex having a concentration of 3% by weight.
In the above case, the light transmittance at a wavelength of 470 nm is 40%.
It means that it is above. The transmittance of the diene copolymer latex (A) is less than 40%.

Examples of the (d) ethylenically unsaturated monocarboxylic acid monomer used in the production of the alkali-soluble latex (B) include acrylic acid, methacrylic acid, crotonic acid, and a half ester of dicarboxylic acid. These ethylenically unsaturated monocarboxylic acid monomers may be used alone or in combination.
A combination of two or more species may be used, and the amount used is 20
~ 50% by weight. If it is less than 20% by weight, a paper coating composition having high water retention cannot be obtained, and if it exceeds 50% by weight, a large amount of aggregates are generated during emulsion polymerization and a stable latex cannot be obtained.

Examples of (e) acrylic acid alkyl esters having an alkyl group having 1 to 8 carbon atoms include methyl acrylate, ethyl acrylate, n-butyl acrylate and 2-ethylhexyl acrylate.
These may be used alone or in combination of two or more, and the amount used is necessarily determined from the amounts of the ethylenically unsaturated monocarboxylic acid monomer and vinyl acetate.

If the vinyl acetate (f) is less than 5% by weight, sufficient water retention cannot be imparted to the coating composition.
If it exceeds 5% by weight, a large amount of aggregates are generated during emulsion polymerization and a stable latex cannot be obtained. In order to obtain the alkali-soluble latex (B), pH is less than 7.5, preferably pH
It is necessary to carry out emulsion polymerization in the region of 3.0 to 5.5. If the pH in the polymerization system is 7.5 or more, a stable alkali-soluble latex cannot be obtained. In addition, since the alkali-soluble latex (B) is remarkably thickened at a pH of 7.5 or more and is difficult to handle, the pH is less than 7.5, preferably the pH.
It is preferable to handle it in the area of 3.0 to 5.5.

Well-known emulsifiers, polymerization initiators, chain transfer agents, polymerization methods and the like are used when emulsion-polymerizing the diene copolymer latex (A) and the alkali-soluble latex (B) in the present invention. As the emulsifier, for example, aliphatic soap, rosin acid soap, alkyl sulfonate, dialkylaryl sulfonate, alkyl sulfosuccinic acid, polyoxyethylene alkyl sulfate,
Anionic surfactants such as polyoxyethylene alkylaryl sulfates, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene sorbitan fatty acid esters, and oxyethyleneoxypropylene block copolymers. To be This surfactant is usually used as an anionic surfactant alone or in a mixed anionic / nonionic system.

The polymerization initiator has a function of radically decomposing by heat or a reducing substance to cause addition polymerization of a monomer. Examples of such a polymerization initiator include water-soluble or oil-soluble peroxo compounds. Disulfate, peroxide,
Azobis compounds and the like, specifically potassium peroxodisulfate, sodium peroxodisulfate, ammonium peroxodisulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, 2,2-azobisisobutyronitrile, cumene hydroperoxide. Among these, peroxodisulfate is particularly preferable.

Examples of the chain transfer agent include mercaptans such as n-butyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, n-dodecyl mercaptan, and t-dodecyl mercaptan, and disulfides such as tetramethyl thiuram disulfide and tetraethyl thiuram disulfide. , Halogenated derivatives such as carbon tetrachloride and carbon tetrabromide, α-methylstyrene dimer, 2-ethylhexyl thioglycolate and the like.

If desired, various polymerization regulators such as sodium hydroxide, potassium hydroxide, sodium hydrogencarbonate, sodium carbonate, and disodium hydrogenphosphate can be added.
Various chelating agents such as H-preparing agent and ethylenediaminetetrasodium can be added. The polymerization temperature in this emulsion polymerization is usually selected in the range of 50 to 100 ° C., but if acceleration of the polymerization or polymerization at a lower temperature is desired, acidic sodium sulfite, ascorbic acid or a salt thereof,
The so-called redox polymerization method can be adopted by using a reducing agent such as erythorbic acid, a salt thereof, or Rongalit in combination with the polymerization initiator.

As the emulsion polymerization method, for example, a batch charging method of the monomer mixture or a method of polymerizing a part of the monomer mixture and then intermittently or continuously adding the remaining monomer mixture is used. You can Alternatively, a method of continuously adding the monomer mixture from the start of the polymerization can be adopted. Next, the paper coating liquid composition of the present invention will be described. The paper coating liquid composition of the present invention contains 4 to 20 parts by weight of the diene copolymer latex (A) and 0.1 to 1 part by weight of the alkali-soluble latex (B) per 100 parts by weight of the pigment. It is characterized by When the amount of the diene copolymer latex (A) used is less than 4 parts by weight, the surface strength of the coated paper is remarkably reduced, which is not preferable. Further, if it is used in an amount of more than 20 parts by weight, the paper coating liquid composition tends to adhere to the roll in the coating step, which causes roll contamination.

When the amount of the alkali-soluble latex (B) used is less than 0.1 part, sufficient water retention cannot be imparted to the paper coating composition, and when it exceeds 1 part, the paper coating composition cannot be used. The viscosity of the coating liquid composition becomes too high, which is not preferable. In the present invention, the particle size of the diene copolymer latex (A) is in the range of 0.06 to 0.16 μm, and the amount of the diene copolymer latex (A) and the alkali-soluble latex (B) used is the above. Only when the content is within the range, good high-speed coating property and white surface feeling can be achieved.

Examples of the pigments used in the paper coating composition include mineral pigments generally used for paper coating such as clay, calcium carbonate, titanium oxide and satin white. Further, a pigment dispersant, a fluorescent dye, a coloring pigment, etc. can be optionally mixed. The pH of the paper coating liquid composition needs to be adjusted to 7.5 to 13.0 with a water-soluble alkaline substance. When the pH of the composition is less than 7.5, the alkali-soluble latex (B) is not completely dissolved, and sufficient water retention cannot be imparted to the paper coating liquid composition. On the other hand, if the pH exceeds 13, the viscosity of the coating liquid composition will remarkably increase and the operability will decrease.

Examples of the alkaline substance used for pH adjustment include commonly used sodium hydroxide, potassium hydroxide, ammonia and the like. The preparation of the paper coating liquid composition was carried out by adding the diene copolymer latex (A) and the alkali-soluble latex (B) to a sufficiently dispersed pigment slurry, stirring the mixture sufficiently, and then adjusting the pH with an alkaline substance. It is preferable to use the method of performing. Regarding the addition of the latex, the diene copolymer latex (A) and the alkali-soluble latex (B) may be added separately, or the diene copolymer latex (A) and the alkali-soluble latex (B) may be added in advance. It is also possible to add a mixture. When mixed in advance, the pH of the diene copolymer latex (A) should be 7.5.
It should be less than 3.0, preferably in the range of 3.0 to 6.0.

In the paper coating liquid composition, if necessary, water-soluble natural polymeric substances such as casein and starch, carboxymethyl cellulose, sodium alginate, or other synthetic water retention agents, for example, those shown in the present invention. It is also possible to add an alkali-soluble latex other than the composition. The paper coating liquid composition of the present invention can be applied to base paper by an ordinary method using various blade coaters such as flooded nips and short dwells.

The coated paper produced using the composition can be subjected to offset printing, gravure printing and the like.

[0029]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Each property was determined as follows. (1) Particle diameter This is an average value of values obtained for 100 latex particles by a transmission electron micrograph. (2) High-speed fluidity (high shear viscosity) Using a Hercules high shear viscometer manufactured by Kumagai Riki, using E
Bob was measured under the condition of 4,400 rotations. The smaller the value, the better the high-speed fluidity. (3) Water retention A particle size gauge (manufactured by Yoshimitsu Scientific Co., Ltd.) is used. Apply the coating solution to the particle size gauge and immediately cover the coated base paper from above.
The time for the coating solution to dry to a gauge depth of 70 microns is measured. The longer the time, the better the water retention. (4) Pick strength Using an RI printing tester (manufactured by Ming Seisakusho), 0.4 cc of printing ink (SD Super Deluxe 50 Hong B made by T & K TOKA Co., Ltd .; Tuck 18) was overprinted and the picking state that appeared on the rubber roll was confirmed. It was lined on another mount and the state was observed. The evaluation was made by a 10-point evaluation method, and the less scored the picking phenomenon, the higher the score. (5) Wet pick strength Using an RI printing tester (manufactured by Ming Seisakusho), water is applied to the coated paper surface with a sleeve roll, and immediately after that, printing ink (T & K) is used.
Toka SD Super Deluxe 50 Red B; Tack 15) 0.4 cc was printed once, and the picking state that appeared on the rubber roll was lined on another mount and the state was observed. The evaluation was made by a 10-point evaluation method, and the less scored the picking phenomenon, the higher the score. (6) Mechanical Stability The mechanical stability of the paper coating solution was measured using the Marron stability test.

Residual occurrence rate of 0.05% or less: ○, residual occurrence rate of 0.05 to 0.2% or less: △ Residual occurrence rate of 0.2% or more: × (7) Blank surface feeling Asahi Kasei formula surface Sensitivity measurement device (Tappi Journal,
p. 89, Vol. 76, No. The one described in 10, 1993) was used.

The average area of one dark part on the coated paper surface is 0.5
Less than mm ² : ○, average area of one dark part on the coated paper is 0.5 mm ² or more: × (8) Gravure suitability Printing speed 60 m / min, printing pressure using the Ministry of Finance Printing Bureau gravure printing suitability tester It was printed at 10 kg / cm ² .
The number of missing dots per cm ^{2 of the} halftone part was counted to obtain the missing rate with respect to the number of halftone dots in the entire halftone part. The smaller the halftone dot dropout rate, the better the gravure suitability. (9) Transmittance Using a photoelectric spectrometer (Model 6B manufactured by Hirama Rika Kenkyusho Co., Ltd.), a wavelength of 470 nm
It was measured at.

Production Example 1 Polymerization of Diene Copolymer Latex (A-1) A pressure resistant reaction vessel equipped with a stirrer and a temperature control jacket was added with 70 parts by weight of water and a polystyrene seed latex having a particle diameter of 0.0215 μm. 45 parts by weight, sodium dodecylbenzenesulfonate 0.1 parts by weight, fumaric acid 2.
5 parts by weight were charged and the temperature was raised to 80 ° C. Then, an initiator comprising 20 parts by weight of water, 1 part by weight of sodium peroxodisulfate, 0.1 part by weight of sodium lauryl sulfate and 0.2 part by weight of sodium hydroxide was added to the monomer mixture shown in Table 1 for 5 hours. The system aqueous solution was added at a constant flow rate for 6 hours. After reacting for another 2 hours and then cooling, the pH of the produced copolymer latex was adjusted to 7 with sodium hydroxide, and then unreacted monomers were removed by steam stripping method. A latex (A-1) was obtained by filtration. The copolymer latex was adjusted so that the final concentration of solid content was 50% by weight.

Next, except that the amount of seed latex used and the composition of the monomer mixture were changed as shown in Table 1,
In the same manner, the copolymer latex (A-
2), (A-3) and copolymer latexes (a-1) and (a-2) used in Comparative Examples were produced. Production Example 2 Production of Alkali-Soluble Latex (B-1) 180 parts by weight of water, 2.0 parts by weight of sodium dodecylbenzene sulfonate, sodium ethylenediaminetetraacetate in a pressure resistant reaction vessel equipped with a stirrer and a temperature control jacket were added. 02 parts by weight were charged and heated to 85 ° C. After replacing the inside of the container with nitrogen, 10 parts by weight of vinyl acetate and 3 parts of methacrylic acid were used.
5 parts by weight, 55 parts by weight of ethyl acrylate, 0.1 parts by weight of dodecyl mercaptan, 40 parts by weight of water, 0.8 parts by weight of sodium peroxodisulfate, 0.8 parts by weight of sodium dodecylbenzenesulfonate, hydroxylated An initiator aqueous solution consisting of 0.2 part by weight of sodium was added dropwise at the same time, the addition was completed in 3 hours while maintaining the temperature at 85 ° C., and the polymerization was further continued for 1 hour. Thus, an alkali-soluble latex (B-1) having a polymerization rate of 98%, a pH of 4.4 and a solid content of 30.2% was obtained. The alkali-soluble latex was diluted to 3% with water, a 3% aqueous solution of sodium hydroxide was added dropwise, and the light transmittance at pH 7.5 was measured to be 52%. confirmed.

Then, the alkali-soluble latex (B-2) used in Examples and the alkali-soluble latex used in Comparative Examples were prepared in the same manner as in Production Example 2 except that the monomers having the compositions shown in Table 2 were used. (B-1) and (b-2) were manufactured.

[0035]

Examples 1 to 3 and Comparative Examples 1 to 3 Using the obtained copolymer latex and alkali-soluble latex, a paper coating composition was prepared according to the following formulation (1). Formulation of paper coating liquid composition (1) Clay: 70, calcium carbonate: 30, dispersant: 0.
2, sodium hydroxide: 0.1, oxidized starch: 4, copolymer latex: 10, alkali-soluble latex:
0.3, water: added so that the total solid content is 64% (unit: parts by weight) The viscosity and water retention of this coating liquid composition are measured, and then the coating amount is 12 g / m ^{2 on} one side. Grammage of 75 g / m ²
It was applied to the base paper. The coating is a cylindrical laboratory coater (CLC6000, made by Warehauser).
Was used at a coating speed of 900 m / min. After coating, supercalendering was performed at a roll temperature of 50 ° C. and a linear pressure of 150 kg / cm to obtain coated paper.

Table 3 shows the results of evaluation of the coated paper thus obtained according to the evaluation method described above.

[0037]

Examples 4 to 7 and Comparative Examples 4 to 7 Copolymer latex (A-1) and alkali-soluble latex (B-
Using 1), a paper coating liquid composition was prepared according to the following formulation (2). The viscosity, water retention and physical properties of the coated paper were measured in the same manner as in Example 1. The results obtained are shown in Table 4.

Formulation of paper coating liquid composition (2) Clay: 70, calcium carbonate: 30, dispersant: 0.
2, sodium hydroxide: 0.1, oxidized starch: the amount shown in Table 4, carboxymethyl cellulose: the amount shown in Table 4,
Copolymer latex (A-1): amount shown in Table 4, alkali-soluble latex (B-1): amount shown in Table 4, water: added so that the total solid content is 64% (unit is parts by weight)

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

As is apparent from the examples, according to the present invention, high-speed fluidity and water retention relating to high-speed coating are excellent,
In addition, it is possible to easily obtain a paper coating liquid composition having excellent white surface feeling of coated paper and excellent gravure printing suitability.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area // (C08L 9/00 33:00) (C08L 9/00 31:04)

Claims (1)

[Claims] 1. The following diene copolymer latex (A) is contained in an amount of 4 to 20 parts by weight and the alkali-soluble latex (B) is included in an amount of 0.1 to 1 part by weight, based on 100 parts by weight of the pigment. Paper coating composition. Diene copolymer latex (A): (a) 20 to 70% by weight of conjugated diene monomer, (b) 0.5 to 10% by weight of ethylenically unsaturated carboxylic acid monomer, (c) other A particle size of 0.0, which is obtained by emulsion polymerization of a monomer mixture composed of 20 to 79.5% by weight of a copolymerizable vinyl monomer.
Diene-based copolymer latex of 6 to 0.16 μm. Alkali-soluble latex (B): (d) 20 to 50% by weight of ethylenically unsaturated monocarboxylic acid monomer, (e) 20 to 75% by weight of alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, (F) Vinyl acetate 5-30
An alkali-soluble latex obtained by emulsion polymerization of a monomer mixture consisting of wt%.