JP2000290538A - Aqueous coating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous coating agent which yields a coated film having an excellent water resistance and solvent resistance. SOLUTION: The titled coating agent comprises an epoxy resin emulsion (A) and at least one hardener (B) chosen from amine compounds, thiol compounds, acid anhydrides, imidazoles and dicyandiamides. Here, the epoxy resin emulsion (A) is obtained by allowing an epoxy resin to react with a vinyl alcohol polymer having at least one functional chosen from an amino group, a carboxyl group and a mercapto group in a molecule, in an aqueous medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an aqueous coating agent, and more particularly, to an aqueous coating agent having excellent water resistance and solvent resistance.

[0002]

2. Description of the Related Art Epoxy resins have excellent adhesiveness to various substrates, heat resistance, corrosion resistance, chemical resistance, electrical properties, and mechanical properties, and are therefore widely used in coating agents, paints, adhesives, and fiber treatment agents. It is used for When epoxy resins are used for the above applications, solvent types in which the epoxy resin is dissolved in various low-boiling solvents are generally used to facilitate handling. The use of low-boiling solvents has been restricted due to problems such as harm to the environment and adverse effects on the global environment.In recent years, an aqueous dispersion of epoxy resin has been developed in which an epoxy resin is dispersed in water using an emulsifier. Has been put to practical use. For example, JP
JP-A-4-15956, JP-A-58-111831, JP-B-6-102748 and the like describe epoxy resin emulsions by forced emulsification, and are described in JP-A-57-108150 and JP-A-57-108150. 61-2438
Japanese Patent No. 22 proposes a modified epoxy resin in which a hydrophilic group is introduced and self-emulsified. However, the aqueous coating agent obtained using the epoxy resin emulsion proposed in these publications has a water resistance of the cured product, solvent resistance, as compared with the non-aqueous epoxy resin adhesive.
It had disadvantages inferior in physical properties such as adhesion to a substrate.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an aqueous coating agent which exhibits excellent water resistance and solvent resistance without the above-mentioned problems. It is a thing.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop an aqueous coating agent having the above-mentioned preferable properties. As a result, in an aqueous medium, an epoxy resin, an amino group in a molecule, An epoxy resin emulsion (A) obtained by reacting a vinyl alcohol polymer having at least one functional group selected from a carboxyl group and a mercapto group and an amine compound, a thiol compound, an acid anhydride, imidazoles and dicyandiamide. The present inventors have found that an aqueous coating agent comprising at least one curing agent (B) is an aqueous coating agent having the intended performance, and have completed the present invention.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the aqueous coating agent of the present invention will be described in detail. The epoxy resin used in the production of the epoxy resin emulsion (A) constituting the aqueous coating agent of the present invention includes, for example, hydroquinone, resorcinol, methylresorcinol, pyrocatechol,
Polyglycidyl ether compounds of mononuclear polyhydric phenol compounds such as phloroglucinol; dihydroxynaphthalene, biphenol, methylene bisphenol (bisphenol F), methylene bis (orthocresol), ethylidene bisphenol, isopropylidene bisphenol (bisphenol A), isopropyl Redidenbis (orthocresol), tetrabromobisphenol A,
1,3-bis (4-hydroxycumylbenzene), 1,
4-bis (4-hydroxycumylbenzene), 1,1,
3-tris (4-hydroxyphenyl) butane, 1,
Polyglycidyl ether compounds of polynuclear polyhydric phenol compounds such as 1,2,2-tetra (4-hydroxyphenyl) ethane, thiobisphenol, sulfobisphenol, oxybisphenol, phenol novolak, orthocresol novolak, resorcinol novolak;
Ethylene glycol, propylene glycol, butylene glycol, hexanediol, polyglycol, thiodiglycol, glycerin, trimethylolpropane,
Polyglycidyl ethers of polyhydric alcohols such as pentaerythritol, sorbitol, bisphenol A-ethylene oxide adduct; maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, suberic acid, adipic acid, azelaic acid, sebacic acid, dimer Aliphatic, aromatic or alicyclic such as acid, trimer acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, endmethylenetetrahydrophthalic acid Homopolymer or copolymer of glycidyl ester of polybasic acid and glycidyl methacrylate; glycidylamino group such as N, N-diglycidylaniline, bis (4- (N-methyl-N-glycidylamino) phenyl) methane Having epoxidation Things; vinylcyclohexene diepoxide, dicyclopentadiene diepoxide, 3,4
Epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6
Methylcyclohexylmethyl-3,4-epoxy-6
Methylcyclohexanecarboxylate, bis (3,4
Epoxides of cyclic olefin compounds such as -epoxy-6-methylcyclohexylmethyl) adipate; epoxidized conjugated diene polymers such as epoxidized polybutadiene and epoxidized styrene-butadiene copolymer; and heterocyclic compounds such as triglycidyl isocyanurate. can give.

Among these epoxy resins, in particular, when at least one polyglycidyl ether compound selected from the group consisting of mononuclear polyhydric phenol or polyglycidyl ether of polynuclear polyhydric phenol and aliphatic polyglycidyl ether is used. In particular, when a bisphenol-type epoxy resin (polyglycidyl ether of alkylidene bisphenol) is used, an aqueous coating agent excellent in corrosion resistance, adhesion to a substrate, and the like can be obtained, which is preferable.

[0007] These epoxy resins may be modified with a diglycidyl ether compound of a polyalkylene oxide such as polyethylene oxide or polypropylene oxide to give self-emulsifiability.

[0008] The amino group in the molecule used in the present invention,
The vinyl alcohol polymer having a carboxyl group or a mercapto group is not particularly limited as long as it is a vinyl alcohol polymer containing an amino group, a carboxyl group or a mercapto group in the molecule, and particularly a primary or secondary amino group. Is preferred. The method for producing a vinyl alcohol polymer having an amino group, a carboxyl group or a mercapto group includes, for example, (1) an ethylenically unsaturated monomer having a primary amino group or a secondary amino group such as vinylformamide and methylvinylacetamide. (2) a method of copolymerizing a monomer or an ethylenically unsaturated monomer having a functional group capable of forming a primary amino group or a secondary amino group by hydrolysis with vinyl acetate, followed by saponification; Addition of a mercaptan having an amino group or a carboxyl group to a side chain epoxy group of a polymer obtained by copolymerizing a monomer having an epoxy group such as allyl glycidyl ether and vinyl acetate with a catalyst such as sodium hydroxide. (3) Functionality capable of reacting with the hydroxyl group of polyvinyl alcohol (4) reacting a compound having an amino group or a carboxyl group with a vinyl alcohol polymer in a molecule with a vinyl alcohol polymer; and (4) a monomer having a carboxyl group such as maleic anhydride or itaconic acid and vinyl acetate. A method of saponifying after copolymerization; (5) A vinyl ester polymer obtained by polymerizing a vinyl monomer mainly comprising a vinyl ester monomer in the presence of thiolacetic acid is obtained by a conventional method. Saponification method; and the like.

The vinyl alcohol polymer may have a functional group other than an amino group, a carboxyl group or a mercapto group in the molecule, as long as the effects of the present invention are not impaired. Examples of monomer units that provide such a functional group include ethylene, propylene, isobutylene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, (anhydrous) fumaric acid, (anhydrous) maleic acid, and (anhydrous)
Itaconic acid, allylsulfonic acid, methallylsulfonic acid,
Vinylsulfonic acid, acrylamide-2-methylpropanesulfonic acid, methacrylamide-2-methylpropanesulfonic acid, sulfopropyl acrylate, sulfopropyl methacrylate, and alkali salts thereof, acrylamide, methacrylamide, trimethyl- (3-acrylamide -3-dimethylpropyl) -ammonium chloride, ethyl vinyl ether, butyl vinyl ether,
Examples include N-vinylpyrrolidone, vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, tetrafluoroethylene, and the like. Further, a polymer having a functional group at a terminal obtained by polymerizing a vinyl ester monomer such as vinyl acetate in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid may be used.

The content of the amino group or carboxyl group of the vinyl alcohol polymer having an amino group or carboxyl group in the molecule used in the present invention is not particularly limited, and a preferable range varies depending on the degree of polymerization and the like. Generally, 0.1 to 15 mol% is preferable, and 0.2 to 10 mol% is more preferable. When the content of the amino group or the carboxyl group is less than 0.1 mol%, the reactivity with the epoxy group in the epoxy resin is lowered, and the epoxy resin may not be emulsified stably. When the content of the amino group or the carboxyl group exceeds 15 mol%, the storage stability of the obtained epoxy emulsion is lowered, and the system may gel.

The degree of saponification of a vinyl alcohol polymer is as follows:
It is preferably at least 50 mol%, more preferably at least 60 mol%, even more preferably at least 70 mol%. Saponification degree 5
If the amount is less than 0 mol%, the water solubility, which is an inherent feature of the vinyl alcohol polymer, is reduced. The degree of polymerization of the vinyl alcohol-based polymer is preferably such that the viscosity average molecular weight according to the JIS method is 100 to 10,000.
More preferably, it is 0 to 8,000. Molecular weight 10
When it is less than 0, the solvent resistance and water resistance of the epoxy emulsion obtained by the production method of the present invention are insufficient, and when the molecular weight exceeds 10,000, when the epoxy resin is emulsified, May become too high to emulsify stably.

The amount of the vinyl alcohol polymer used relative to the epoxy resin is 100 parts by weight of the epoxy resin.
It is 0.2 to 20 parts by weight, preferably 0.5 to 15 parts by weight. If the added amount is less than 0.2 parts by weight, the emulsification may not be carried out stably. If the added amount exceeds 20 parts by weight, the storage stability of the obtained epoxy emulsion may decrease, May gel. The addition of the vinyl alcohol-based polymer is usually performed in an aqueous solution,
Ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; ethyl acetate;
Esters such as butyl acetate; dimethylformamide, N
May be added by dissolving it in a mixed solvent of water and an organic solvent such as amides such as methylpyrrolidone.

In the present invention, when a vinyl alcohol polymer having a mercapto group is used as the vinyl alcohol polymer, a vinyl alcohol polymer having a mercapto group is added to an epoxy resin in an aqueous medium in an aqueous medium. It is preferred to carry out the reaction in the presence of The alkali catalyst used here is not particularly limited,
Sodium hydroxide, potassium hydroxide, sodium methylate, sodium acetate, sodium bicarbonate, sodium carbonate, monoethanolamine, diethanolamine,
Triethanolamine, triethylamine and the like. Although the amount of the alkali catalyst used is not particularly limited, it is usually based on 100 parts by weight of the vinyl alcohol-based polymer.
0.1 to 10 parts are used. If the amount is less than 0.1 part, the reaction between the epoxy resin and the mercapto group may be difficult to proceed, and if it is more than 10 parts, the stability of the epoxy resin may be impaired. As the vinyl alcohol-based polymer having a mercapto group, a vinyl alcohol-based polymer having a mercapto group at one molecular end is preferable.

As a method for producing an epoxy resin emulsion, when an epoxy resin is emulsified in an aqueous medium,
Or after emulsification, a method of adding a vinyl alcohol polymer having at least one functional group selected from an amino group, a carboxyl group and a mercapto group in the molecule, and reacting the resulting mixture to produce an epoxy resin emulsion is preferred. is there. The emulsification of the epoxy resin is performed using an emulsifying and dispersing device such as a homomixer and a homogenizer. At this time, the emulsification temperature is not particularly limited, but is usually 5 to 70 ° C.

The epoxy resin emulsion used in the present invention
(A) When the vinyl alcohol-based polymer has an amino group, the epoxy resin and the vinyl alcohol-based polymer unit are generally bonded by a structural unit represented by the following general formula 1. It is presumed that the water-based coating agent of the present invention contributes to good water resistance, solvent resistance and the like.

[0016]

Embedded image

In emulsifying the epoxy resin, a surfactant may be used in combination. Examples of the surfactant include nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and a polyoxyethylene-polyoxypropylene block copolymer. Activator: Anionic surfactants such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium alkyldiphenylether disulfonate and sodium di (2-ethylhexyl) sulfosuccinate can be used.

The epoxy resin emulsion used for the aqueous coating agent of the present invention usually has a solid content of about 20 to about 20%.
The content is adjusted to 65% by weight, but is not limited thereto. When an organic solvent is used in the production of the emulsion, the organic solvent can be removed by distillation or stripping as necessary.

The curing agent (B) used in the aqueous coating agent of the present invention is at least one curing agent selected from amine compounds, thiol compounds, dicyandiamide, acid anhydrides and imidazoles. As the amine compound, ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, diethylenetriamine,
Dipropylene triamine, triethylene triamine, tetraethylene pentamine, dipropylene triamine, dimethylaminopropylamine, aliphatic polyamines such as diethylaminopropylamine, mensendiamine,
1,3-bis (aminomethyl) cyclohexane, isophoronediamine, N-3-aminopropylcyclohexylamine, 1,4-diaminocyclohexane, 2,4-diaminocyclohexane, bis (aminocyclohexyl)
Methane, 1,3-bis (aminocyclohexylpropane), bis (3-methyl-4-aminocyclohexyl)
Alicyclic polyamines such as methane, 1,4-bis (ethylamino) cyclohexane, m-xylylenediamine, p
-Xylylenediamine, 4- (1-aminoethyl) aniline, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, bis (3-ethyl-4-amino-5-methylphenylmethane), 1,4-
Bis [2- (3,5-dimethyl-4-aminophenyl)
Propyl] benzene, aromatic polyamines such as N-aminoethylpiperazine, 1,4-bis (3-aminopropyl) piperazine, and other heterocyclic polyamines such as polyamine-based curing agents; these polyamines and dimer acid; A polyamide polyamine curing agent obtained by reacting a dicarboxylic acid by an ordinary method is exemplified. Tertiary amines can also be used as the amine compound. The tertiary amine is not particularly limited, but tris (dimethylaminomethyl) phenol, dimethylbenzylamine, 1,8-diazabicyclo (5,4,0) undecane and the like are mainly used.

In the curing agent (B) used in the aqueous coating agent of the present invention, the thiol compound is not particularly limited as long as it has two or more mercapto groups. Examples of such compounds include Capcure3-800, CapcureWR-6, EpomateQX11, and Epom manufactured by Yuka Shell Epoxy Co., Ltd.
ateQX40, Adeka Hardener EH316, manufactured by Asahi Denka Kogyo Co., Ltd.
ADEKA HARDNER EH317 and the like.

Among the curing agents (B) used in the aqueous coating agent of the present invention, the acid anhydrides include dodecenyl succinic anhydride, polyadipic anhydride, polyazeline anhydride,
Aliphatic acid anhydrides such as polysebacic anhydride, poly (ethyloctadecanoic anhydride), poly (phenylhexadecanoic anhydride), methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhymic anhydride , Hexahydrophthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride,
Alicyclic acid anhydrides such as methylcyclohexene dicarboxylic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride,
And aromatic acid anhydrides such as ethylene glycol bis trimellitate and glycerol tristrimellitate.

Among the curing agents (B) used in the aqueous coating agent of the present invention, imidazole compounds are not particularly restricted but include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole and the like. Tertiary amines and imidazoles are often used in combination with other curing agents such as acid anhydrides and thiol compounds. Other examples of the curing agent (B) include dicyandiamide.

The aqueous coating agent of the present invention may contain another aqueous emulsion as required. The aqueous emulsion is not particularly limited, but conventionally known urethane dispersion, vinyl acetate polymer emulsion, vinyl acetate- (meth) acrylate copolymer emulsion, ethylene-vinyl acetate copolymer emulsion, ethylene-vinyl acetate -(Meth) acrylate copolymer emulsion, ethylene-vinyl chloride copolymer emulsion, ethylene-vinyl acetate-vinyl chloride copolymer emulsion, ethylene-vinyl acetate-third
Grade carboxylic acid vinyl ester copolymer emulsion,
Acetic acid such as (meth) acrylate (co) polymer emulsion, styrene- (meth) acrylate copolymer emulsion, styrene-butadiene copolymer emulsion, styrene- (meth) acrylate-butadiene copolymer emulsion Examples include vinyl resin emulsions, (meth) acrylate emulsions, and diene resin emulsions.

If necessary, various organic solvents such as toluene, perchrene, dichlorobenzene, trichlorobenzene, starch, modified starch, oxidized water, etc., may be used to adjust the drying property, setting property, viscosity, film forming property and the like. Starch, sodium alginate, carboxymethylcellulose,
Water-soluble polymers such as methyl cellulose, hydroxymethyl cellulose, maleic anhydride / isobutene copolymer, maleic anhydride / styrene copolymer, maleic anhydride / methyl vinyl ether copolymer, polyvinyl alcohol, urea / formalin resin, urea / melamine / Holimarin resin, phenol / Holimarin resin, etc., thermosetting resins, clay, kaolin, talc, calcium carbonate, filler such as wood flour, filler such as flour, boric acid,
Reaction accelerators such as aluminum sulfate, pigments such as titanium oxide, and other various additives such as antifoaming agents, dispersants, antifreezing agents, preservatives, and rust inhibitors can be appropriately added.

The aqueous coating agent obtained by the present invention can be used for a wide range of applications, for example, a primer coating agent, a top coating agent for films and sheets of various plastics such as polyester, nylon, PVC, ABS, OPP, CPP, etc. As a surface coating agent for various metal plates such as iron plate, steel plate, aluminum plate, etc., as a top coat agent for various functional papers such as thermal paper, or as a coating agent for various textiles, natural leather, artificial leather, synthetic leather, wood, etc. Useful as

[0026]

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples,
And "%" mean by weight unless otherwise specified.

Example 1 Amino group-containing polyvinyl alcohol (polyvinyl alcohol obtained by copolymerizing vinyl formamide and vinyl acetate followed by saponification: degree of polymerization 350, degree of saponification 98.5 mol%, primary amino group content 1.5 Mol%, 5% of PVA-1)
While vigorously stirring 100 g of the aqueous solution at 20 ° C. with a homomixer, 100 g of a bisphenol A type epoxy resin (Epicoat 828; manufactured by Yuka Shell Epoxy) was added and emulsified to obtain a stable emulsion having a solid concentration of 50.5%. Aqueous coating agent was prepared by adding 30 parts of Adeka hardener EH-220 (manufactured by Asahi Denka Kogyo) to 100 parts of the obtained epoxy resin emulsion. The following tests were performed using this aqueous coating agent. Evaluation of aqueous coating agent An aqueous coating agent was applied to each material such as a PET film, a PVC sheet, and an aluminum plate so as to have a film thickness of 20 μm, and was dried at 80 ° C. as a test piece.
The following evaluations were performed. Table 1 shows the results. (Evaluation of solvent resistance) Acetone was applied to the surface of the coating film of the test piece, and a rubbing test was performed to rub the surface of the test piece, and the appearance of the coating film was changed. The evaluation results are ◎ very good, ○ good, △
Slightly poor, x: peeling off of coating film, etc. (Evaluation of Water Resistance) The test piece was immersed in water at 20 ° C. for one week, and the change in the appearance of the coating film was observed. The evaluation results are shown as ◎ very good, 一部 partly whitened, Δwhitened, and x-peeled.

Example 2 The procedure of Example 1 was repeated, except that the thiol-based curing agent Adeka Hardener EH316 (manufactured by Asahi Denka Kogyo KK) was used instead of the amine-based curing agent used in Example 1. The test was performed. The results are shown in Table 1.

Example 3 The procedure of Example 1 was repeated, except that 15 parts of a tertiary amine compound, tris (dimethylaminomethyl) phenol, was used instead of 30 parts of the amine-based curing agent used in Example 1. The test was performed. The results are shown in Table 1.

Example 4 Instead of using 30 parts of the amine type curing agent used in Example 1, an imidazole compound; 2-methylimidazole 10
The test was performed in the same manner as in Example 1 except that the parts were used.
The results are shown in Table 1.

Example 5 Example 1 was repeated except that 10 parts of trimellitic anhydride was used instead of 30 parts of the amine-based curing agent used in Example 1.
The test was performed in the same manner as described above. The results are shown in Table 1.

Example 6 A test was performed in the same manner as in Example 1 except that 10 parts of dicyandiamide was used instead of 30 parts of the amine-based curing agent used in Example 1. The results are shown in Table 1.

Comparative Example 1 A test was conducted in the same manner as in Example 1 except that 30 parts of the amine-based curing agent used in Example 1 was not used. The results are shown in Table 1.

Example 7 Instead of using the amino group-containing polyvinyl alcohol used in Example 1, the amino group-containing polyvinyl alcohol was copolymerized with allyl glycidyl ether and vinyl acetate, and then 2-aminothiophenol was reacted with NaOH as a catalyst. Polyvinyl alcohol obtained by addition and further saponification: a polymerization degree of 500, a saponification degree of 97.5 mol%, a primary amino group modification amount of 1.0 mol%, and the same procedure as in Example 1 except that PVA-2) was used. Similarly, an epoxy resin emulsion was obtained and tested. The results are shown in Table 1.

Example 8 Instead of using the amino group-containing polyvinyl alcohol used in Example 1, amino group-containing polyvinyl alcohol (polyvinyl alcohol obtained by copolymerizing methylvinylacetamide and vinyl acetate and then saponifying:
An epoxy resin emulsion was obtained in the same manner as in Example 1 except that the degree of polymerization was 750, the degree of saponification was 87.5 mol%, the amount of secondary amino group modification was 2.5 mol%, and PVA-3). went. The results are shown in Table 1.

Example 9 Instead of using the amino group-containing polyvinyl alcohol used in Example 1, a carboxyl group-containing polyvinyl alcohol (polyvinyl alcohol obtained by copolymerizing maleic anhydride and vinyl acetate and then saponifying: An epoxy resin emulsion was obtained and tested in the same manner as in Example 1 except that a degree of saponification of 1700, a degree of saponification of 98.5 mol%, a carboxyl group modification amount of 2.5 mol%, and PVA-4) were used. The results are shown in Table 1.

Example 10 Instead of using the amino group-containing polyvinyl alcohol used in Example 1, a mercapto group-containing polyvinyl alcohol (polyvinyl alcohol obtained by polymerizing vinyl acetate in the presence of thiolacetic acid followed by saponification: 1500,
Degree of saponification 96.0 mol%, mercapto group content 1.5 ×
An epoxy resin emulsion was obtained and tested in the same manner as in Example 1 except that 10 ^-5 equivalent / g, PVA-1) was used. The results are shown in Table 1.

Comparative Example 2 Instead of using the amino group-containing polyvinyl alcohol used in Example 1, unmodified polyvinyl alcohol (manufactured by
Kuraray PVA-117: polymerization degree 1700, saponification degree 98.5
An attempt was made to produce an epoxy resin emulsion in the same manner as in Example 1 except that mol%, PVA-5) was used. However, a non-emulsified component was produced, and a stable emulsion was not obtained.

Comparative Example 3 An epoxy resin was prepared in the same manner as in Example 1 except that the amino group-containing polyvinyl alcohol used in Example 1 was replaced with a nonionic emulsifier (Emulken 985 manufactured by Kao Corporation). An emulsion was obtained and tested. The results are shown in Table 1.

[0040]

[Table 1]

[0041]

The aqueous coating agent of the present invention can be used in a wide range of applications because it provides a film having excellent water resistance, solvent resistance, etc., and can be used for polyester, nylon, PVC, ABS,
As a primer coat agent, a top coat agent or a base polymer of an aqueous gravure ink for various plastic films and sheets such as OPP and CPP, iron plate, steel plate,
It is useful as a surface coating agent for various metal plates such as aluminum plates, as a top coat agent for various functional papers such as thermal paper, or as a coating agent and paint for various textiles, natural leather, artificial leather, synthetic leather, wood and the like. .

Claims (3)

[Claims] 1. An epoxy resin in an aqueous medium,
Epoxy resin emulsion (A) obtained by reacting a vinyl alcohol polymer having at least one functional group selected from an amino group, a carboxyl group and a mercapto group in a molecule with an amine compound, a thiol compound, an acid anhydride, and imidazole Coating agent comprising at least one curing agent (B) selected from the group consisting of carboxylic acids and dicyandiamide. 2. The aqueous coating agent according to claim 1, wherein the vinyl alcohol-based polymer is a vinyl alcohol-based polymer containing a primary or secondary amino group. 3. An epoxy resin emulsion (A) obtained by reacting a vinyl alcohol polymer having a mercapto group in a molecule with an epoxy resin in an aqueous medium in the presence of an alkali catalyst. The aqueous coating agent according to claim 1.