JP3175543B2 - Aqueous paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based coating composition, and more particularly, to a water-based coating composition having excellent foam-suppressing and defoaming properties suitable for inner surface coating of metal cans and the like.

[0002]

2. Description of the Related Art In the field of paints, there have been studies on the transition to water-based paints for various applications in order to avoid problems caused by the use of solvents.
In particular, paints used for the inner surface coating of food and beverage metal cans are desired to be switched to water-based paints in terms of resource saving, energy saving, low pollution, and safety.
As the resin for the water-based paint, like the solvent-based paint, epoxy resin is mainly studied from the viewpoint of the properties of the film,
Various techniques for suitably dispersing an epoxy resin in water have been proposed. Among these techniques, the method of dispersing an epoxy resin using a surfactant is not suitable for practical use because the epoxy resin is deteriorated by the surfactant used and tends to have poor dispersion stability over time. .

In order to solve this drawback, an epoxy resin having a self-emulsifying property has been obtained by modifying the epoxy resin. Representative examples thereof include JP-A-55-75460 and JP-A-57-10.
Nos. 5418 and 53-1228, for example, acrylic acid and carboxyl groups in a carboxyl group-containing acrylic resin obtained by copolymerizing a monomer containing methacrylic acid and an aromatic epoxy resin. A method of partially esterifying an epoxy group, introducing a carboxyl group into the epoxy resin, and neutralizing the carboxyl group with a base to make the epoxy resin aqueous, and the like. In each of the above techniques, an emulsifying segment is introduced into an epoxy resin by the action of acrylic acid or methacrylic acid. It has also been proposed to produce an aqueous resin dispersion in which an epoxy resin is dispersed by forcibly dispersing an unmodified epoxy resin and a phenol resin using the surface active action of an acrylic resin, and use the resultant in a paint. ing.

[0004] However, these water-based paints have high thixotropic properties, and therefore, there is a possibility that defects may occur in the coating depending on the application method.

As a method for applying these water-based paints, it is possible to form a film having a certain degree of uniformity by using a spray coating method which is a closed system. When using a system roll coating, the water-based paint is agitated by the rolls, and since the water-based paint is circulated, air is entrapped and a large amount of bubbles are generated, and a film defect caused by the bubbles is generated. was there. This is a serious problem particularly in the inner surface coating of a can enclosing a food or the like. That is, when a film defect occurs, the food comes into direct contact with the metal surface of the can, which may cause deterioration or deterioration of the food, which may cause safety and hygiene problems. In order to prevent this, it has been considered to add an antifoaming agent, but a known effective antifoaming agent is a silicon-based one. Because of the fear, it could not be used for coating the inner surface of a food can that directly contacts the food.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to improve the dispersion stability of an aqueous paint base such as an epoxy resin, and to suppress the foaming property. It is an object of the present invention to provide a water-based coating composition which is excellent in defoaming properties, can form a defect-free film, and is suitable for inner surface coating of a highly safe can which can be used for foods and the like.

[0007]

The aqueous coating composition according to claim 1 of the present invention has a solid content of 10% in the aqueous coating base (A).
0.001 to 0.5 part by weight of a copolymer (B) obtained by polymerizing an unsaturated monomer comprising the following (a) to (c) with 0 part by weight is neutralized with an amine to make water soluble. It is an aqueous coating composition containing the following. (A) 2-ethylhexyl acrylate and / or 2
-Ethylhexyl methacrylate: 50% by weight or more (b) unsaturated monomer having a carboxyl group: 5 to 30
(C) Other unsaturated monomers copolymerizable with the above (a) and (b): 45% by weight or less

[0008] The aqueous coating composition according to claim 2 of the present invention is the aqueous coating composition according to claim 1, wherein the aqueous coating base (A) contains a self-emulsifiable epoxy resin and a phenol resin. Aqueous resin dispersion (A1), an aqueous resin dispersion containing a self-emulsifying epoxy resin and an amino resin (A2), or an epoxy resin and a phenolic resin are forced into an aqueous medium using an acrylic resin. (A3), which is one of

[0009]

Next, the present invention will be described in more detail. In the present invention, the copolymer (B) that contributes to the foam-suppressing property and the defoaming property contains 50% by weight of 2-ethylhexyl acrylate and / or 2-ethylhexyl methacrylate (a) (hereinafter abbreviated as alkyl ester (a)). % Is obtained by polymerizing an unsaturated monomer mixture containing at least 10% by weight.

Which can be copolymerized with the alkyl ester (a)
As the unsaturated monomer (b) having a carboxyl group,
Acrylic acid, methacrylic acid, itaconic acid, crotonic acid,
Maleic acid and anhydrides thereof are mentioned, and acrylic acid and methacrylic acid are particularly preferable.

Other unsaturated monomers (c) copolymerizable with the above (a) and (b) include alkyl esters of acrylic acid and / or methacrylic acid having an alkyl group having 3 or less carbon atoms; Acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate and other unsaturated monomers having a hydroxyl group; 2-hydroxylethyl acrylate, 2-hydroxylethyl methacrylate, allyl alcohol, vinyl alcohol and other unsaturated monomers; styrene, α-methylstyrene, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, acrylonitrile and the like.

Examples of the amine used for neutralizing the copolymer (B) include alkylamines such as trimethylamine, triethylamine and butylamine, and alcoholamines such as 2-dimethylaminoethanol, diethanolamine, triethanolamine and aminomethylpropanol. , Morpholine and the like are used. Also, polyamines such as ethylenediamine and diethylenetriamine can be used.
It is preferable to neutralize at least 80 equivalents or more of the carboxyl group in the unsaturated monomer having a carboxyl group (b) with the amine. If the neutralization ratio is less than 80 equivalents, it becomes difficult to uniformly mix in the paint, which is not preferable.

The copolymer (B) formed from these unsaturated monomer mixtures is added in an amount of 0.001 to 0.5 parts by weight based on 100 parts by weight of the solid content of the aqueous paint base. 0.
It is preferable to add from 01 to 0.5 parts by weight. If the amount added is less than 0.001 part by weight, the defoaming property is insufficient, and
If the amount exceeds 5 parts by weight, the strength of the formed film is reduced.

The aqueous paint base used in the aqueous paint composition of the present invention is not particularly limited, and the aqueous paint base itself can withstand heat sterilization and can form a good film on a metal surface. If present, it can be used arbitrarily in order to exhibit excellent defoaming properties by adding the copolymer. In the present invention, the aqueous paint base refers to a material in the aqueous paint composition that contributes to the formation of a coating film. Typical water-based paint bases include water-based paint bases mainly composed of epoxy resin from the viewpoint of film strength, durability and stability, and various self-emulsifying epoxy resins combined with amino resin or phenol resin And a dispersion in which an epoxy resin and a phenol resin are forcibly dispersed in an aqueous medium using an acrylic resin.

As the self-emulsifying epoxy resin, a) a carboxyl group in a carboxyl group-containing acrylic resin obtained by copolymerizing a monomer containing acrylic acid and methacrylic acid and an epoxy group in an aromatic epoxy resin are converted into dimethylaminoethanol. , Those obtained by partially esterifying in the presence of an esterification catalyst such as diethanolamine, introducing a carboxyl group into the epoxy resin, and rendering the epoxy resin aqueous by neutralizing the carboxyl group with a base,
b) Acrylic-modified epoxy resin in which a carboxyl group of acrylic acid or methacrylic acid and an epoxy group in the epoxy resin are partially esterified in the presence of an esterification catalyst such as sodium hydroxide to introduce an acryloyl group into the epoxy resin. To obtain a carboxyl group in the epoxy resin by copolymerizing the acrylic-modified epoxy resin and acrylic acid, a monomer containing methacrylic acid,
An epoxy resin made aqueous by neutralizing the carboxyl group with a base. C) Polymerizing the epoxy resin and a monomer containing acrylic acid or methacrylic acid in the presence of a radical generator such as a peroxide. By
Acrylic acid on the fatty chain skeleton of the epoxy resin, a polymer obtained by graft polymerization of methacrylic acid, and a graft modified product that is a mixture of a carboxyl group-containing acrylic resin is obtained.
Aqueous epoxy resin is obtained by neutralizing a carboxyl group in the graft-modified product with a base. An aqueous paint base is obtained by combining the self-emulsifying epoxy resin with an amino resin or a phenol resin.

D) The epoxy resin and the phenol resin are forcibly dispersed by applying a high shearing force by utilizing the surface active action of the acrylic resin, and after adding water to phase inversion, removing the solvent if desired. An aqueous paint base using the aqueous resin dispersion obtained in this manner can be used.

The epoxy resin used herein is obtained by condensing bisphenols such as bisphenol A, bisphenol B and bisphenol F with epichlorohydrin in the presence of an alkali catalyst. Epicoat 1004, Epicoat 1007, Epicoat 1009, Epicoat 1010
(Above, trade names), PKHH (trade name, manufactured by Phenoxy Associates) and the like. Further, a modified epoxy resin or a phenoxy resin obtained by reacting a denaturant such as bisphenol A or a vegetable oil fatty acid such as dehydrated castor oil fatty acid, soybean oil fatty acid or coconut oil fatty acid with the epoxy group or hydroxyl group of the bisphenol type epoxy resin is also used. be able to.

The amount of the water-based paint base agent can be arbitrarily selected depending on the type of the substrate to which the water-based paint composition is applied, the desired film strength, and the like.

In addition to the above, the aqueous coating composition of the present invention contains an organic solvent and a surfactant in order to improve the coating properties and to impart functions according to the use within the range not impairing the effects of the present invention. And additives such as a slipping agent, a rust preventive, a pigment and a filler.

The base material such as a metal plate to which the aqueous coating composition of the present invention is applied includes an untreated steel plate, a treated steel plate, a zinc plate,
Tinplate steel, such as tin plate, chromium-plated steel plate and chromic acid-treated steel plate, nickel-plated steel plate, aluminum-plated steel plate, and aluminum.

The method of coating the metal plate is not particularly limited, and examples thereof include spray coating such as air spray, airless spray and electrostatic spray, roll coater coating, immersion coating, and electrodeposition coating. Of these, the effect of the present invention is particularly remarkable when applied to roll coater coating, in which film defects due to the generation of bubbles are problematic.

The baking conditions for the aqueous coating composition of the present invention are not particularly limited, but generally the temperature is 150 to 23.
0 ° C. and the baking time are selected from the range of 2 to 30 minutes.

[0023]

EXAMPLES The present invention will be described in more detail with reference to specific examples, but the present invention is not limited thereto.
Hereinafter, unless otherwise specified, “parts” and “%” represent “parts by weight” and “% by weight”, respectively.

(Production Example 1) Synthesis of copolymer (A-1) (1) 186 parts of 2-butanol (2) 47 parts of 2-butanol (3) 80 parts of 2-ethylhexyl acrylate (4) 10 parts of methacrylic acid (5) Styrene 10 parts (6) Azobisisobutyronitrile 1 part (7) Dimethylethanolamine 10 parts (8) Water 324 parts Charge (1) in a four-necked flask filled with nitrogen gas,
The mixed solution of (2) to (6) was added over 2 hours. 10
The mixture was heated to 0 ° C., stirred for 3.5 hours, (7) and (8) were added, and the mixture was stirred for 10 minutes.
1) A solution was obtained.

(Production Example 2) Synthesis of copolymer (A-2) (1) 186 parts of 2-butanol (2) 47 parts of 2-butanol (3) 60 parts of 2-ethylhexyl methacrylate (4) 20 parts of methacrylic acid (5) Methyl methacrylate 20 parts (6) Benzoyl peroxide 1 part (7) Dimethylethanolamine 21 parts (8) Water 313 parts Charge (1) into a four-necked flask filled with nitrogen gas,
The mixed solution of (2) to (6) was added over 2 hours. 10
The mixture was heated to 0 ° C., stirred for 3.5 hours, (7) and (8) were added, and the mixture was stirred for 10 minutes.
2) A solution was obtained.

(Production Example 3) Synthesis of copolymer (A-3) (1) 186 parts of 2-butanol (2) 47 parts of 2-butanol (3) 90 parts of 2-ethylhexyl acrylate (4) 10 parts of methacrylic acid (5) Benzoyl peroxide 1 part (6) Dimethylethanolamine 10 parts (7) Water 324 parts Charge (1) in a four-necked flask filled with nitrogen gas,
The mixed solution of (2) to (5) was added over 2 hours. 10
The mixture was heated to 0 ° C., stirred for 3.5 hours, (6) and (7) were added, and the mixture was stirred for 10 minutes.
3) A solution was obtained.

(Production Example 4) Synthesis of copolymer (B-1) (1) 200 parts of propylene glycol monopropyl ether (2) 300 parts of 2-butanol (3) 133 parts of methacrylic acid (4) 100 parts of styrene 5) Ethyl acrylate 100 parts (6) Benzoyl peroxide 12 parts (1) and (2) in a four-necked flask filled with nitrogen gas
And 1/4 of the mixture of (3) to (6) was added. After heating to 100 ° C, with stirring (3) ~
The remaining amount of the mixed solution of (6) was added dropwise over 2 hours. After completion of the dropwise addition, the mixture was further stirred for 2 hours while maintaining the temperature at 100 ° C. Thus, a copolymer having a solid content of 40% (B-1)
A solution was obtained.

(Production Example 5) Synthesis of copolymer (B-2) (1) n-butanol 598 parts (2) styrene 60 parts (3) ethyl acrylate 120 parts (4) methyl methacrylate 60 parts (5 ) Methacrylic acid 160 parts (6) Benzoyl peroxide 2 parts Into a four-necked flask filled with nitrogen gas, half of each of (1) to (6) was charged, heated and maintained at 90 ° C. 90 ° C
Then, the remaining amount of the mixed solution of (1) to (6) was added dropwise over 2 hours while stirring. After the completion of dropping, the temperature is set to 9
While maintaining the temperature at 0 ° C, the mixture was further stirred for 5 hours. Thus, a copolymer (B-2) solution having a solid content of 39.1% and a weight average molecular weight of 112,000 was obtained.

(Production Example 6) Phenol resin (C-1)
Preparation of solution (1) 80 parts of ion-exchanged water (2) 72 parts of a 21.5% aqueous sodium hydroxide solution (3) 140 parts of bisphenol A (4) 37 parts of formalin 400 parts (5) 20% hydrochloric acid 70 parts (6) 180 parts of 1-butanol (1) to (4) were charged into a four-necked flask filled with nitrogen gas, reacted at 50 ° C. for 2 hours, and then heated to 70 ° C. for 1 hour. This gave a red-brown transparent resin solution. The resin solution was cooled to 40 ° C., and (5) was added. In a few minutes, the upper layer was separated into a colorless and transparent aqueous layer and the lower layer into a brown organic layer. After separating the upper layer by decantation, (6) was added to obtain a phenol resin (C-1) solution having a solid content of 54%.

(Production Example 7) Phenol resin (C-2)
Preparation of solution (1) bisphenol A 264 parts (2) p-cresol 66 parts (3) 37% folimarin 176 parts (4) 25% ammonia water 20 parts In a four-necked flask filled with nitrogen gas, (1) to ( 3) was charged, heated and melted at 80 ° C. for 30 minutes, then cooled to 70 ° C., and (4) was added dropwise while paying attention to heat generation. The reaction was performed for 3 hours while maintaining the reaction temperature at 80 ° C. After the reaction, a mixed solvent 47 of 50% butyl acetate and 50% n-butanol was used.
The mixture was extracted with 4 parts, dehydrated over about 3 hours by heating and refluxing at a temperature of 90 to 110 ° C.
%, A phenolic resin having a weight average molecular weight of 1560 (C-
2) A solution was obtained.

(Production Example 8) Preparation of self-emulsifying epoxy resin (D-1) (1) 66 parts of propylene glycol monopropyl ether (2) Epicoat 1009 (manufactured by Yuka Shell Epoxy Co., Ltd.) 200 parts (3) 150 parts of copolymer resin (B-1) solution (4) 13 parts of dimethylaminoethanol (5) 871 parts of ion-exchanged water (1) and (2) in a four-necked flask filled with nitrogen gas
And stirred under heating at 120 ° C. for 2 hours to dissolve the epoxy resin. Then, after cooling and adding (3), 1
While stirring at 00 ° C., (4) was added, and the mixture was reacted for 1 hour and then cooled. After cooling to 60 ° C.,
It was dropped over 20 minutes to obtain the desired self-emulsifying epoxy resin (D-1). 20% solids in paint, 12% solvent, 18 sec. Viscosity at # 4 Ford Cup at 25 ° C
Met.

(Production Example 9) Water-based paint base (D-2)
Preparation of self-emulsifying epoxy resin (D-1) 1 in Production Example 8
The phenolic resin described in Production Example 6 (C-
1) 2.0 parts of the solution was added with stirring at room temperature to obtain an aqueous paint base (D-2). The solids content of this paint is 2
0%, viscosity 16 sec / 25 ° C. in a # 4 Ford cup.

(Production Example 10) Water-based paint base (D-
Preparation of 3) [A. Preparation of Epoxy-Modified Resin] (1) 350 parts of ethylene glycol monoethyl ether (2) 645 parts of Epicoat 1100L (manufactured by Yuka Shell Epoxy Co., Ltd.) (3) 1 part of a 10% sodium hydroxide aqueous solution 1 part (4) hydroquinone 02 parts (5) Methacrylic acid 4 parts In a four-necked flask filled with nitrogen gas (1) and (2)
And stirred under heating at 120 ° C. for 2 hours to dissolve the epoxy resin. Thereafter, the temperature was increased, and (3) to (5) were added while stirring at 130 ° C., and the reaction was carried out for 3 hours while maintaining the temperature at 130 ° C., followed by cooling and taking out. The obtained resin solution had a solid content of 64.5% and a resin acid value of 0.2 (per solid content). [B. Production of Aqueous Dispersion] (1) Methyl isobutyl ketone 23 parts (2) Epoxy-modified resin (A) 171 parts (3) Styrene 16.7 parts (4) Ethyl acrylate 19.5 parts (5) Methacrylic acid 19 0.5 parts (6) butyl cellosolve 33.4 parts (7) azobisisobutyronitrile 2.4 parts (8) azobisisobutyronitrile 0.6 part (9) methyl ethyl ketone 10 parts (10) dimethylaminoethanol 8 Part (11) Ion-exchanged water 537 parts Charged (1) into a four-necked flask filled with nitrogen gas,
While refluxing at 80 ° C., the mixed solution of (2) to (7) was added dropwise over 3 hours. After completion of the dropwise addition, the temperature was raised to 90 ° C., and (8) was added 60 minutes after the completion of the dropwise addition. After further reacting at 90 ° C. for 60 minutes, it was cooled. After the temperature was lowered to 70 ° C., (9) and (10) were added. Then (11) is changed to 1
It was added dropwise over 20 minutes to obtain an aqueous dispersion. The solid content of the dispersion was 19.7%, the amount of solvent was 15%, and the viscosity was 15 seconds / 25 ° C in a # 4 Ford cup. [C] Preparation of water-based paint base (D-3) 3.0 parts of the phenol resin solution (C-1) of Production Example 6 was stirred at room temperature with respect to 100 parts of the aqueous dispersion (b). To give a water-based paint base (D-3).
This coating had a solids content of 21% and a viscosity of 17 seconds / 25 ° C. in a # 4 Ford cup.

(Production Example 11) Water-based paint base (D-
Preparation of 4) [d] Production of aqueous dispersion (1) 100 parts of ethylene glycol monobutyl ether (2) 60 parts of 1-butanol (3) 150 parts of Epicoat 1010 (manufactured by Yuka Shell Epoxy Co., Ltd.) 150 parts (4) Methacryl Acid 20 parts (5) Styrene 10 parts (6) Ethyl acrylate 7.5 parts (7) Benzoyl peroxide 2 parts (8) Dimethylaminoethanol 15 parts (9) Ion exchange water 285 parts (10) Ion exchange water 350 parts (1) to (3) were charged into a four-necked flask filled with nitrogen gas, and heated and dissolved. After heating to 110 ° C., while stirring, a solution in which (4) to (7) were uniformly mixed and dissolved was
It was added dropwise over 2 hours. After the completion of the dropwise addition, the temperature was maintained at 110 ° C., the mixture was stirred for 4 hours, and then cooled. After the temperature was lowered to 80 ° C., a mixed solution of (8) and (9) was added dropwise over 60 minutes. After the completion of the dropwise addition, (10) was added dropwise over 120 minutes to obtain an aqueous dispersion. The neutralization ratio of the carboxyl groups contained in the acrylic resin in the dispersion was 72.5 mol%,
The solid content of this dispersion was 18.8%, the amount of solvent was 16%, and the viscosity was 18 seconds / 25 ° C. in a # 4 Ford cup. [E] Preparation of aqueous paint base (D-4) 2.0 parts of the phenol resin solution (C-1) of Production Example 6 was added at room temperature to 100 parts of the aqueous dispersion described in [D]. Water-based paint base (D-4) added with stirring
I got The paint had a solids content of 20% and a viscosity of 19 seconds / 25 ° C. in a # 4 Ford cup.

(Production Example 12) Water-based paint base (D-
Preparation of 5) [F] Preparation of epoxy resin solution (1) Epicoat 1009 (manufactured by Yuka Shell Epoxy Co., Ltd.) 40 parts (2) butyl acetate 45 parts (3) n-butanol 15 parts Nitrogen gas sealed 4 (1) to (3) were charged into a one-necked flask, gradually heated, heated to 110 ° C., and dissolved over 3 hours to obtain an epoxy resin solution having a solid content of 40.0%. [G] Preparation of mixed solution of epoxy resin and phenol resin (1) Epoxy resin solution 80 parts (2) Phenol resin (C-2) solution (Production Example 7) 20 parts Epoxy resin solution of (1) and (2) A mixed solution having a solid content of 40.1% obtained by mixing the phenol resin solution was obtained. [H] Preparation of water-based paint (D-5) (1) 340 parts of a mixed liquid of epoxy resin and phenol resin (the above [G]) (2) 60 parts of copolymer resin (B-2) solution (Production Example 5) 3) 15 parts of 25% ammonia water (4) 225 parts of ion-exchanged water (5) 360 parts of ion-exchanged water (1) and (2) are sufficiently stirred until uniform in the reaction vessel, and then vigorously stirred. The mixed solution of (3) and (4) was gradually dropped. After sufficiently stirring until the system became uniform, (5) was gradually added dropwise with vigorous stirring to obtain a dispersion having a solid content of 16.0%. afterwards,
38.0% solids by azeotropic distillation at 60-90 torr
Most of the solvent was removed with water until isobutanol and butyl carbitol were each finally present in the paint at 5%. It was added to a concentration of 10% and diluted with ion-exchanged water to obtain an aqueous paint base (D-5). This paint base had a solids content of 28.3% and a viscosity of 45 seconds / 25 ° C. in a # 4 Ford cup.

(Examples 1 to 3 and Comparative Examples 1 to 4) (Preparation and evaluation of aqueous coating composition) The aqueous coating bases (D-2) to (D-5) obtained in Production Examples 8 to 10 were prepared. make use of,
Water-based coating compositions were prepared in the amounts shown in Table 1. Copolymer resins (A-1) to (A-3) described in Production Examples 1 to 3
Examples 1 to 5 were prepared by blending the solution as an antifoaming agent.
It was set to 3.

[0037]

[Table 1]

100 ml of each water-based coating composition was placed in a volume of 500
Weighed into a graduated cylinder of ml. 1m diameter at the tip
m was inserted into the paint in the measuring cylinder, and nitrogen gas was flowed at a flow rate of 200 ml / min for 3 minutes. Thereafter, the volume of the foam-containing paint was immediately measured, and the results of evaluating the defoaming property according to the following criteria were shown in Table 1. (Evaluation criteria) Volume of paint containing foam is less than 110 ml: ◎ (very excellent in defoaming property) Volume of paint containing foam is 110 ml or more and less than 150 ml: ○ (excellent in defoaming property) Contains foam The volume of the paint containing the foam was 150 ml or more and less than 300 ml: Δ (slightly inferior in defoaming properties) The volume of the paint containing foam was 300 ml or more: × (poor in defoaming properties) Examples 1 to 7, which are the aqueous coating compositions of the present invention, had excellent defoaming properties, but Comparative Examples 1 to 4 to which other defoaming agents were added were found to have poor defoaming properties. When these paints were applied to a metal plate by roll coating, the metal plates to which the paints of Examples 1 to 4 were applied were visually observed, and no film defects due to bubbles were observed. In each of the metal plates to which the paint was applied, occurrence of film defects due to bubbles was observed.

[0039]

Since the aqueous coating composition of the present invention has the above-mentioned constitution, the dispersion stability of an aqueous coating base such as an epoxy resin can be improved, and a film having excellent foam suppressing and defoaming properties and having no defects can be obtained. It shows an excellent effect that it can be formed, and has high safety that can be used for foods and the like.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C09D 133/06

Claims (2)

(57) [Claims] 1. A solid content of 100 of an aqueous paint base (A).
The parts by weight, and neutralized by the following (a) ~ unsaturated monomer obtained by polymerizing a copolymer consisting of (c) (B) 0.001~0.5 parts <br/> amine An aqueous coating composition comprising a water-soluble coating composition. (A) 2-ethylhexyl acrylate and / or 2-ethylhexyl methacrylate: 50% by weight or more (b) Carboxyl group-containing unsaturated monomer: 5 to 30
(C) Other unsaturated monomers copolymerizable with the above (a) and (b): 45% by weight or less 2. A water-soluble paint base (A) is an aqueous resin containing an aqueous resin dispersion containing a self-emulsifying epoxy resin and the phenol resin (A1) or, alternatively a self-emulsifying epoxy resin and an amino resin dispersion (A2) or, alternatively an epoxy resin and a phenolic resin that is dispersed forcibly aqueous medium using an acrylic resin (A3), the aqueous coating of claim 1, wherein a is either Composition.