JPH10324720A - Aqueous copolymer dispersion and aqueous coating resin composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject dispersion excellent in initial dryability and initial coating film's water resistance and useful in such uses as coating materials and inks, by including a specific amount of a multivinyl compound as a copolymer component of a carbonyl group-contg. copolymer. SOLUTION: This aqueous copolymer dispersion is obtained by emulsion polymerization, in the presence of an emulsifier (e.g. anionic surfactant), of a monomer mixture comprising (A) 0.1-30 pts.wt. of a polymerizable unsaturated monomer bearing at least one carbonyl group in one molecule (e.g. diacetoneacrylamide), (B) 0.05-5 wt.% of a multivinyl compound bearing at least two polymerizable unsaturated bonds in one molecule, (C) 0-10 wt.% of a water-soluble ethylenic unsaturated monomer (e.g. maleic acid), and (D) 55-99.85 wt.% of another ethylenic unsaturated monomer (vinyl acetate).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous dispersion of a copolymer which is excellent in initial drying property and water resistance of an initial coating film and is useful for applications such as room temperature drying type paints, inks and adhesives. The present invention relates to a water-based resin composition for a paint.

[0002]

2. Description of the Related Art In recent years, in the fields of paints, inks, adhesives, etc., there has been a shift from an organic solvent type to an aqueous type in terms of resource saving, environmental hygiene, no pollution, and non-hazardous materials (Fire Defense Law). Is underway. Generally, aqueous paints for drying at room temperature include:
An acrylic copolymer emulsion is used as a vehicle component. The acrylic copolymer emulsion is to form a film by fusing emulsion particles after coating, and in order to secure film forming property by such fusing, the glass transition temperature of the copolymer is designed to be high. It was difficult. For this reason, the coating film formed from the water-based paint using the copolymer emulsion was inferior in the toughness and stain resistance of the film, and the water resistance was undeniable.

In order to solve the problem at the time of forming the emulsion of the water-based paint, the applicant of the present invention used a carbonyl group-containing copolymer emulsion and a hydrazide compound to form a crosslinker between emulsion particles with a crosslinking agent having a relatively small molecular weight. It was proposed to crosslink (JP-A-4-249587), thereby reinforcing the film-forming properties and realizing not only stain resistance and water resistance but also improved initial drying properties.

However, in the production of the above carbonyl group-containing copolymer emulsion, the type and amount of the monomer which is a copolymer component are determined depending on the purpose required for the emulsion particles. In some cases, the group could not be introduced, and there was no problem after sufficiently drying in terms of water resistance, but there was a problem at the time of the initial coating film. On the other hand, for example, Japanese Patent Application Laid-Open No. 57-3850 proposes that carbonyl group-containing copolymer emulsion particles have a multilayer structure having a core and a shell. This measure has the advantage that the range of choice of the copolymer component can be expanded according to the purpose required for the emulsion particles, but the curability, the initial drying property, and the water resistance of the initial coating film are insufficient.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, by using a specific amount of a polyvinyl compound as a copolymer component of a carbonyl group-containing copolymer, the emulsion particles have been prepared in advance. The present inventors have found that the inside can be crosslinked to some extent and the initial drying property and the water resistance of the initial coating film can be improved without lowering the mechanical performance, and have reached the present invention.

That is, the present invention provides (a) 0.1 to 30% by weight of a polymerizable unsaturated monomer having at least one carbonyl group in one molecule, and (b) at least two polymerizable unsaturated monomers in one molecule. A polyvinyl compound having a polymerizable unsaturated bond
To 5% by weight, (c) water-soluble ethylenically unsaturated monomer
A monomer mixture containing 55 to 99.85% by weight of (d) other ethylenically unsaturated monomers in the presence of an emulsifier. (B) at least two polymerizable unsaturated monomers in one molecule; and (b) at least two polymerizable unsaturated monomers having one or more carbonyl groups in one molecule. The polyvinyl compound having a bond is used in an amount of 0.
A monomer containing 0.5 to 5% by weight, (c) 0 to 10% by weight of a water-soluble ethylenically unsaturated monomer, and (d) 55 to 99.95% by weight of another ethylenically unsaturated monomer. The copolymer (I) obtained by emulsion-polymerizing the polymer mixture in the presence of an emulsifier is used as a core component, and (e) a carbonyl group-containing polymerizable unsaturated monomer is added to an aqueous dispersion containing the copolymer (I). 0.1 to 30% by weight, (f) 0 to 10% by weight of a water-soluble ethylenically unsaturated monomer, and (g) 60 to 99.9% by weight of another ethylenically unsaturated monomer. A copolymer aqueous dispersion obtained by adding a monomer mixture and emulsion-polymerizing the copolymer (II) as a shell component, and an aqueous dispersion of these copolymers, Further, it has at least two or more hydrazide groups per molecule as a crosslinking agent. A resin composition for water-based paint, wherein a hydrazide compound is blended such that the hydrazide group in the hydrazide compound is 0.01 to 2 mol per 1 mol of a carbonyl group contained in the aqueous copolymer dispersion. It provides things.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the polymerizable unsaturated monomer (a) having at least one carbonyl group in one molecule used in the present invention, for example, acrolein, diacetone acrylamide, diacetone methacrylamide,
Formyl styrene, vinyl alkyl ketones having 4 to 7 carbon atoms (eg, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) and the like.
Of these, diacetone acrylamide and diacetone methacrylamide are particularly preferred.

[0008] The polyvinyl compound (b) having at least two polymerizable unsaturated bonds in one molecule used in the present invention includes a polymerizable unsaturated monocarboxylic acid ester of a polyhydric alcohol and a polybasic acid. And polymerizable unsaturated alcohol esters and aromatic compounds substituted with two or more vinyl groups. Specific examples thereof include allyl (meth) acrylate and ethylene glycol di (meth) acrylate. -To, triethylene glycol di (meth)
Acrylate, tetraethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol di (meth) acrylate ) Acrylate, neopentylglycol di (meth) acrylate
G, 1,6-hexanediol- (meth) acryle
Pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethanedi (meth) Acrylate, 1,
1,1-trishydroxymethylethanetri (meth) acrylate, 1,1,1-trishydroxymethylpropanetri (meth) acrylate, triallyl isocyanurate, diallyl terephthalate, divinylbenzene, etc. Is mentioned.

The water-soluble ethylenically unsaturated monomer (c) used in the present invention can be copolymerized with the monomer (a) and has strong hydrophilicity as it is or by neutralization or quaternary salification. The monomers shown may be any of anionic, cationic and nonionic monomers.
Examples of the monomer (c) include anionic ones such as (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate, 2-acrylamido-2-methylpropanesulfonic acid, and allylsulfonic acid. Styrene sulfonic acid sodium salt, sulfoethyl methacrylate and its sodium salt and ammonium salt; in the cationic system, for example, (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate; Glycidyl (meta)
Adducts of acrylates and amines; nonionics include (meth) acrylates having a polyoxyethylene chain.

Other ethylenically unsaturated monomers (d) used in the present invention include, for example, methyl (meth)
Acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate,
Alkyl having 1 to 24 carbon atoms of (meth) acrylic acid such as 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate; Cycloalkyl ester; hydroxyalkyl ester of (meth) acrylic acid having 2 to 8 carbon atoms such as 2-hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; vinyl fragrance such as styrene and vinyltoluene Group compounds: N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate,
Examples thereof include vinyl acetate and (meth) acrylonitrile, which are appropriately used depending on desired performance.

The first copolymer aqueous dispersion of the present invention [I]
Means that the monomer (a) is 0.1 to 30% by weight, preferably 0.5 to 25% by weight, and the monomer (b) is 0.05 to 5% by weight, preferably 0.1 to 4% by weight. %, The monomer (c) is 0 to
10% by weight, preferably 0.1-8% by weight, and 55-99.85% by weight of monomer (d), preferably 63-9%
It is obtained by emulsion polymerization of a monomer mixture containing 9.3% by weight in the presence of an emulsifier. Examples of the emulsifier include anionic surfactants and nonionic surfactants, and emulsification using a polymerization initiator such as a persulfate or a peroxide in the presence of one or more of the emulsifiers. Can be polymerized.

When the amount of the monomer (a) is less than 0.1% by weight,
When the curing property with the crosslinking agent component is inferior, when it exceeds 30% by weight, the resulting coating film is liable to crack and the monomer (b)
Is less than 0.05% by weight, the water resistance and curability of the initial coating film are insufficient. On the other hand, if it exceeds 5% by weight, the film-forming properties of the emulsion particles are reduced, and the monomer (c) contains Exceeding the range is not preferred because the hydrophilicity becomes too strong and the water resistance of the coating film deteriorates.

The second copolymer aqueous dispersion of the present invention [II]
First, a monomer mixture forming a core component is subjected to a first-stage emulsion polymerization using a polymerization initiator in the presence of an emulsifier to obtain an aqueous dispersion of a copolymer (I). In the dispersion,
The monomer mixture forming the shell component is subjected to the second stage of emulsion polymerization using a polymerization initiator to obtain an aqueous dispersion of core-shell particles. At the time of the emulsion polymerization in the second stage, it is usually desirable that the emulsifier is not added, or even if it is added, the amount is such that new particles are not formed.

The copolymer (I) as the core component contains the monomer (a) in an amount of 0 to 30% by weight, preferably 0 to 25% by weight, and the monomer (b) in an amount of 0.05 to 5% by weight. %, Preferably 0.1 to 4% by weight, monomer (c) at 0 to 10% by weight, preferably 0.1 to 8% by weight, and monomer (d) at 55 to 55% by weight.
It is obtained by using a monomer mixture containing 99.95% by weight, preferably 63 to 99.8% by weight.

In the copolymer (I), the monomer (a)
On the other hand, if it exceeds 30% by weight, the resulting coating film is liable to crack, etc., and if the monomer (b) is less than 0.05% by weight,
When the water resistance and the curability of the initial coating film are insufficient, on the other hand, when it exceeds 5% by weight, the film-forming property of the emulsion particles decreases, and when the monomer (c) exceeds 10% by weight, the hydrophilicity becomes strong. It is not preferable because the water resistance of the coating film becomes too poor.

On the other hand, the copolymer (II) as the shell component is
Carbonyl group-containing polymerizable unsaturated monomer (e)
30% by weight, preferably 0.5 to 25% by weight, 0 to 10% by weight, preferably 0.1 to 8% by weight of the water-soluble ethylenically unsaturated monomer (f), and other ethylenically unsaturated monomers 60 to 99.9% by weight of the monomer (g), preferably 67
It is obtained by using a monomer mixture containing 99.4% by weight.

In the copolymer (II), if the amount of the monomer (e) is less than 0.1% by weight, the curability with the crosslinking agent component is inferior. However, if the amount of the monomer (f) exceeds 10% by weight, the hydrophilicity becomes too strong and the water resistance of the coating film deteriorates.

The carbonyl group-containing polymerizable unsaturated monomer (e) can be appropriately selected from those listed in the description of the monomer (a) and can be used. The body (f) can be appropriately selected from those listed in the description of the monomer (c) and used. The other ethylenically unsaturated monomer (g) can be appropriately selected from those listed in the description of the monomer (d).

The weight ratio of the solid content of the copolymer (I) as the core component and the copolymer (II) as the shell component is determined based on 100 parts by weight of (I) in view of film forming property and initial water resistance. It is appropriate that (II) be 400 to 25 parts by weight, preferably 300 to 30 parts by weight.

The resin composition for water-based paint of the present invention contains the above copolymer aqueous dispersion [I] and / or [II] as a vehicle component. Further, if necessary, known emulsions conventionally used in the field of coatings, such as vinyl acetate emulsion, acrylic resin emulsion, vinyl acetate-acryl emulsion, ethylene-vinyl acetate emulsion, etc., are solid components in total vehicle components. You may mix | blend the quantity which makes the ratio which occupies in 50 weight% or less.

The composition of the present invention further contains a hydrazide compound having at least two or more hydrazide groups per molecule as a crosslinking agent.

The hydrazide compound includes, for example, saturated aliphatic carboxylic acid dihydrazide having 2 to 18 carbon atoms such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide and sebacic acid dihydrazide. A dihydrazide of a monoolefinically unsaturated dicarboxylic acid such as maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide; reaction of carbonic acid dihydrazide, bissemicarbazide, a polyisocyanate compound with an active hydrogen compound having a hydrophilic group such as a polyoxyethylene chain; Semicarbazide compound obtained by reacting a product with a hydrazine derivative (see JP-A-8-151358); dihydrazide of phthalic acid, terephthalic acid or isophthalic acid; Hydrazide, trihydrazide or tetrahydrazide; nitrilotriacetic acid trihydrazide, trihydrazide citrate, 1,2,4-benzenetricarboxylic hydrazide; ethylenediaminetetraacetic acid tetrahydrazide,
1,4,5,8-naphthoic acid tetrahydrazide; a polyhydrazide obtained by reacting a low polymer having a carboxylic acid lower alkyl ester group with hydrazine or hydrazine hydrate (hydrazine hydroxide) (Japanese Patent Publication No. 52-2287)
No. 8).

When the hydrazide compound is too hydrophobic, it is difficult to disperse it in water, and a uniform crosslinked coating film cannot be obtained. Therefore, it is preferable to use a compound having a moderate hydrophilicity and a relatively low molecular weight. In the above examples, for example, dihydrazide of dicarboxylic acid such as adipic dihydrazide and succinic dihydrazide is preferable.

The hydrazide compound is added in an amount of 0.01 to 2.0 mol, preferably 0.05 to 1 mol, per mol of the carbonyl group in the components [I] and [II]. A suitable amount is 0.5 mol.

In producing a coating material using the composition of the present invention, a pigment, a filler, an aggregate, a pigment dispersant,
Wetting agents, defoamers, plasticizers, film-forming auxiliaries, organic solvents, preservatives, fungicides, pH adjusters, rust inhibitors, etc. can be appropriately selected and combined according to the respective purposes. it can.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

Preparation of Copolymer Aqueous Dispersion [I] Example 1 28.5 ml of deionized water was placed in a two-liter four-necked flask.
0.1 part by weight of Newcol 707SF (manufactured by Nippon Emulsifier Co., Ltd., anionic surfactant having a polyoxyethylene chain, non-volatile content of 30%) was added.
C. 3% by weight of a pre-emulsion obtained by emulsifying the following composition and 25% by weight of 10.5 parts by weight of a solution obtained by dissolving 0.5 part by weight of ammonium persulfate in 10 parts by weight of deionized water. Addition, addition 2
After 0 minute, the remaining pre-emulsion and the remaining aqueous solution of ammonium persulfate were added dropwise over 4 hours.

Deionized water 36.8 parts by weight Styrene 15 parts by weight Methyl methacrylate 41.3 parts by weight n-butyl acrylate 24 parts by weight 2-ethylhexyl acrylate 15 parts by weight Diacetone acrylamide 2 parts by weight 1 2,6-hexanediol diacrylate 0.5 parts by weight Hydroxyethyl acrylate 2 parts by weight Acrylic acid 0.2 parts by weight Newcol 707SF 6.6 parts by weight 143.4 parts by weight After holding at 85 ° C for a time,
The temperature was lowered to 40-60 ° C. Then, pH 8 with ammonia water
To 9 to obtain a copolymer aqueous dispersion [I-1] having a solid content of 55% by weight. The pH of the emulsion was 8.3.

Examples 2 to 4 and Comparative Examples 1 and 2 An aqueous dispersion of a copolymer [I-2] was prepared in the same manner as in Example 1 except that the monomers in the pre-emulsion to be dropped had the compositions shown in Table 1. ] To [I-6]. Table 1 shows the property values of each aqueous dispersion of the copolymer.

[0030]

[Table 1]

Preparation of Copolymer Aqueous Dispersion [II] Example 5 28.5 L of deionized water was placed in a two-liter four-necked flask.
0.1 part by weight of Newcol 707SF (manufactured by Nippon Emulsifier Co., Ltd., anionic surfactant having a polyoxyethylene chain, non-volatile content of 30%) was added.
C. 3% by weight of a pre-emulsion (for core) obtained by emulsifying the following composition and 0.5%
25 parts by weight of 10.5 parts by weight of a solution in which 10 parts by weight of ammonium persulfate was dissolved in 10 parts by weight of deionized water were added, and 20 minutes after the addition, 67% by weight of the pre-emulsion and 50 parts by weight of an aqueous ammonium persulfate solution were added. % By weight was added dropwise over 2 hours.

Deionized water 36.8 parts by weight Styrene 15 parts by weight Methyl methacrylate 43.3 parts by weight n-butyl acrylate 24 parts by weight 2-ethylhexyl acrylate 15 parts by weight 1,6-hexanediol acrylyl -0.5 parts by weight Hydroxyethyl acrylate 2 parts by weight Acrylic acid 0.2 parts by weight Newcol 707SF 6.6 parts by weight Total 143.4 parts by weight After completion of dropping, the mixture was kept at 85 ° C. for 2 hours. rear,
30% by weight of a pre-emulsion (for shell) obtained by emulsifying the following composition and 25% by weight of the above-mentioned aqueous solution of ammonium persulfate were added dropwise thereto over 2 hours.

Deionized water 36.8 parts by weight Styrene 15 parts by weight Methyl methacrylate 38.8 parts by weight n-butyl acrylate 24 parts by weight 2-ethylhexyl acrylate 15 parts by weight Diacetone acrylamide 5 parts by weight Hydroxy Ethyl acrylate 2 parts by weight Acrylic acid 0.2 parts by weight Newcol 707SF 6.6 parts by weight 143.4 parts by weight After completion of dropping, this was further kept at 85 ° C. for 2 hours.
The temperature was lowered to 40-60 ° C. Then, pH 8 with ammonia water
To 9 to obtain a copolymer aqueous dispersion [II-1] having a solid content of 55% by weight. The pH of the emulsion was 8.4.

Examples 6 to 8 and Comparative Examples 3 and 4 The monomers in the core and shell pre-emulsions to be dripped have the compositions shown in Table 2, and the ratios of the core and shell pre-emulsions used are shown in Table 2. The aqueous dispersion of copolymer [II-2] was prepared in the same manner as in Example 5 except that the ratio was as shown in Example 5.
To [II-6]. Table 2 shows the property values of each aqueous dispersion of the copolymer.

[0035]

[Table 2]

Preparation of Resin Compositions Examples 9 to 16 and Comparative Examples 5 to 8 Each of the copolymer aqueous dispersions was charged into a 2 liter container.
Further, adipic dihydrazide was blended with the hydrazide group to the molar amount shown in Table 3 with respect to the carbonyl group in each copolymer aqueous dispersion, and the mixture was stirred, mixed, and further adjusted to pH 7 to 9 with aqueous ammonia. Thus, respective resin mixtures were obtained.

Each of the obtained resin mixtures was subjected to the following performance tests. Table 3 shows the results.

(* 1) Swelling ratio of solvent Each resin mixture obtained as described above was placed on a glass plate by a doctor.
Paint with a blade to a dry film thickness of 60 μm,
After drying for one week under the conditions of a temperature of 20 ° C. and a relative humidity of 75%, the dried film was peeled from the glass plate, cut into a size of 4 × 4 cm, and immersed in xylene at 20 ° C. for 24 hours. . Next, the film was taken out, the xylene on the surface was removed, and the film weight S (g) was measured.
After drying for an hour, the film weight D (g) was measured. The solvent swelling ratio (%) was calculated according to the following equation.

Solvent swelling ratio (%) = (S / D) × 100 (* 2) Gel fraction Each resin mixture obtained as described above was placed on a glass plate by a doctor.
Paint with a blade to a dry film thickness of 60 μm,
After drying for 1 week at a temperature of 20 ° C. and a relative humidity of 75%, the dried film was peeled off from the glass plate, immersed in acetone, and extracted at reflux temperature for 24 hours. The fraction was calculated.

Gel fraction (%) = (weight of membrane after extraction / weight of membrane before extraction) × 100 (* 3) Initial water resistance −
Paint with a blade to a dry film thickness of 60 μm,
After drying at a temperature of 20 ° C. and a relative humidity of 75% for 1 hour, the test plate was half-submerged in 20 ° C. water, and after 30 minutes, the test plate was pulled up and the coated surface was visually evaluated.

：: No abnormality Δ: Slight whitening (blueing) ×: Significant whitening

[0042]

According to the present invention, a certain amount of a polyvinyl compound is used as a copolymer component of a carbonyl group-containing copolymer, so that the emulsion particles are crosslinked to some extent in advance, and the particles are crosslinked with carbonyl and hydrazide. By doing so, a room temperature drying type water-based paint resin composition having good water resistance particularly at the initial stage of coating can be obtained. Therefore, the composition of the present invention is very suitable for outdoor use and is useful as a vehicle component of architectural exterior paints.

[0043]

[Table 3]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 57/10 C08L 57/10 C09D 157/10 C09D 157/10

Claims (4)

[Claims] (1) 0.1 to 30% by weight of a polymerizable unsaturated monomer having at least one carbonyl group in one molecule; and (b) at least two polymerizable unsaturated monomers in one molecule. 0.05 to 5% by weight of a polyvinyl compound having a saturated bond,
(C) 0 to 10% by weight of a water-soluble ethylenically unsaturated monomer, and (d) 55% of another ethylenically unsaturated monomer.
An aqueous dispersion of a copolymer, which is obtained by emulsion-polymerizing a monomer mixture containing 99 to 85% by weight in the presence of an emulsifier. 2. (a) 0 to 30% by weight of a polymerizable unsaturated monomer having at least one carbonyl group in one molecule, and (b) at least two polymerizable unsaturated bonds in one molecule. From 0.05 to 5% by weight of a polyvinyl compound having
(C) 0 to 10% by weight of a water-soluble ethylenically unsaturated monomer, and (d) 55% of another ethylenically unsaturated monomer.
The copolymer (I) obtained by emulsion-polymerizing a monomer mixture containing ．99.95% by weight in the presence of an emulsifier is used as a core component, and an aqueous dispersion containing this is
(E) a carbonyl group-containing polymerizable unsaturated monomer of 0.1 to
30% by weight of (f) water-soluble ethylenically unsaturated monomer
(G) a copolymer (II) obtained by emulsion polymerization by adding a monomer mixture containing 60 to 99.9% by weight of (g) other ethylenically unsaturated monomers.
A water dispersion of a copolymer, characterized by comprising as a shell component. (A) 0.1 to 30% by weight of a polymerizable unsaturated monomer having at least one carbonyl group in one molecule, and (b) at least two polymerizable unsaturated monomers in one molecule. 0.05 to 5% by weight of a polyvinyl compound having a saturated bond,
(C) 0 to 10% by weight of a water-soluble ethylenically unsaturated monomer, and (d) 55% of another ethylenically unsaturated monomer.
水 99.85% by weight of a monomer mixture containing an aqueous dispersion of a copolymer obtained by emulsion polymerization in the presence of an emulsifier, and as a crosslinking agent, at least two or more hydrazide groups per molecule. A hydrazide compound having a carbonyl group 1 contained in the aqueous copolymer dispersion.
The hydrazide group in the hydrazide compound is present in an amount of 0.
A resin composition for a water-based paint, which is blended in an amount of from 0.1 to 2 mol. 4. A polymerizable unsaturated monomer having at least one carbonyl group in one molecule of (a) 0 to 30% by weight, and (b) at least two polymerizable unsaturated bonds in one molecule. From 0.05 to 5% by weight of a polyvinyl compound having
(C) 0 to 10% by weight of a water-soluble ethylenically unsaturated monomer, and (d) 55% of another ethylenically unsaturated monomer.
The copolymer (I) obtained by emulsion-polymerizing a monomer mixture containing ．99.95% by weight in the presence of an emulsifier is used as a core component, and an aqueous dispersion containing this is
(E) a carbonyl group-containing polymerizable unsaturated monomer of 0.1 to
30% by weight of (f) water-soluble ethylenically unsaturated monomer
(G) a copolymer (II) obtained by emulsion polymerization by adding a monomer mixture containing 60 to 99.9% by weight of (g) other ethylenically unsaturated monomers.
And a hydrazide compound having at least two or more hydrazide groups per molecule as a cross-linking agent is added to a 1 mol of carbonyl group contained in the aqueous copolymer dispersion. A hydrazide group in the hydrazide compound in an amount of 0.01 to 2 mol.