JPS6011754B2 - thermosetting coating composition - Google Patents

Description

Detailed Description of the Invention The present invention is an aqueous polymer obtained by emulsion polymerization of a vinyl monomer containing a crosslinkable unsaturated monomer in the presence of an epoxy resin using a water-soluble thermosetting acrylic resin as an emulsifier. The dispersion provides a highly competitive coating with significantly improved mechanical properties, adhesion, water resistance, chemical resistance and salt spray resistance. Moreover, the present invention relates to a thermosetting coating composition that is effective in preventing air pollution and water pollution due to its low content of organic solvent in volatile components.

Conventionally, thermosetting water-based paints have been widely used as pollution countermeasures such as air pollution prevention, but these water-based paints can be roughly divided into water-dispersed types, in which resin components are dispersed in water, and those in which resin components are dissolved in water. There are two types of aqueous solutions available, but at the current stage neither is satisfactory and has several drawbacks.

For example, in the water-dispersed paint that is the object of the present invention, the gloss of the resulting coating is poor, the surfactant used as an emulsifier remains in the paint film, so the water resistance and weather resistance are unsatisfactory, and the water solubility Even if a crosslinking agent such as amino resin is used in combination, fusion with the dispersed resin particles in the aqueous dispersion and uniform mixing are insufficient, resulting in insufficient curing properties and generally poor water resistance and solvent resistance. It will be done. The present invention was achieved as a result of various studies aimed at overcoming the drawbacks of conventional water-dispersed paints using surfactants in order to solve the above-mentioned problems.

That is, the present invention comprises 5 to 6% by weight of hydroxyalkyl acrylate and/or hydroxyalkyl methacrylate, 5 to 2% by weight of acrylic acid and/or methacrylic acid, and the following general formula (wherein R is a hydrogen atom or In the methyl group, R' is a hydrogen atom or Cn 5 n+, where n is an integer of 1 to 4.

) of the compound '1) 2, and the weight percent of the monoethylenically unsaturated monomer 9 that can be polymerized with them, and the compound '11 and the monoethylenically unsaturated monomer 9. Using a water-soluble copolymer obtained by copolymerizing and neutralizing monomer components having a total amount of 2% by weight or more as an emulsifier, 5 to 3% by weight of an epoxy resin, the weight of the compound {1-5 to 5 %, and vinyl monomer 20
It consists essentially of an aqueous polymer dispersion obtained by emulsion polymerization of a monomer mixture containing an epoxy resin of ~9% by weight, and if necessary, a 'B-amino resin is combined with a pinwheel aqueous dispersion at a solid content weight ratio. The present invention relates to a thermosetting coating composition characterized in that it is blended in an amount of 40% or less with respect to 100 to 60% of a liquid. Moreover, the thermosetting coating composition obtained in the present invention has an organic solvent content of 3 to 3% by weight in volatile components, which meets the object of the present invention. The hydroxyalkyl acrylate and hydroxyalkyl methacrylate, which are the first component of the monomer components constituting the emulsifier used to obtain the aqueous polymer dispersion of the present invention, include 2-hydroxyethyl acrylate, 2-hydroxyalkyl methacrylate,
One or more selected from hydroxyethyl, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, etc. can be used, and the amount ranges from 5 to 5 based on the total amount of monomer components constituting the emulsifier. It is appropriate to use 6% by weight, preferably as low as 10 to 4% by weight; if it is less than 5% by weight, it will cause a decrease in crosslinking properties, and if it is more than 6% by weight, it will cause an increase in hydrophilic groups. The water resistance of the formed coating film is also poor.

Furthermore, the amount of the second component (acrylic acid and/or methacrylic acid) of the monomers constituting the emulsifier is preferably within the range of 5 to 2% by weight, and the amount of the second component and its neutralization amount are It is possible to arbitrarily adjust the polymer particle diameter in the aqueous polymer dispersion. If the second component is less than 5% by weight, a stable aqueous polymer dispersion cannot be obtained, and if it is more than 2% by weight, the obtained aqueous polymer dispersion becomes viscous steel, which is also stable. inferior to sex. Also,
Examples of the compound m represented by the above general formula, which is the third monomer component constituting the emulsifier, include N-methylol acrylamide, N-methylol methacrylamide, N-
Butoxymethylacrylamide “N-butoxymethyl,
Monomers having a self-reduction resistant functional group such as methacrylamide can be mentioned, and the amount thereof is suitably 2% by weight or less.

Note that even if compound m is not used as a third component in the emulsifier, the object of the present invention will not be impaired as long as a sufficient amount of compound [1-] is contained in the polymer particles described below. Further, if the amount of the compound {1} is more than 2% by weight, it is not preferable because it may cause gelation during the production of the emulsifier.
Furthermore, as the fourth component of the monomers constituting the emulsifier, that is, the monoethylene unsaturated monomer that can be polymerized with the above-mentioned first to third components to form a water-soluble I type copolymer, an alkyl acrylate monomer is used. esters (e.g., methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, cyclohexyl acrylate, etc.), alkyl methacrylates (e.g., methyl methacrylate) , ethyl methacrylate, propyl methacrylate, butyl methacrylate, isoptyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, etc.), acrylade, methacrylamide, acrylonitrile, methacrylonitrile, styrene, substituted styrenes , vinyl chloride, vinyl acetate, etc., and the amount thereof is not more than 9% by weight, and if the amount is more than that, the object of the present invention cannot be achieved.

In addition, the total amount of the compound represented by the general formula '1) which is the third component of the monomers constituting the emulsifier and the fourth component of the monomers constituting the emulsifier, that is, the monoethylene unsaturated monomer is If the total amount is less than 2% by weight, the object of the present invention cannot be achieved.

The emulsifier used in the present invention can be obtained by polymerizing the monomer components consisting of the above-mentioned first to fourth components in an organic solvent using a suitable polymerization initiator by a known method, and neutralizing the monomer components.

Examples of organic solvents used here include alcohol solvents such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and butyl alcohol; ether alcohol solvents such as methyl cellosolve, cellosolve, butyl cellosolve, methyl carbitol, carbitol, and butyl carbitol; Organic solvents that are freely miscible with water are used, such as ester solvents such as methyl cellosolve acetate and cellosolve acetate, and ketone solvents such as acetone. In addition, as a polymerization initiator, an azo compound such as azobisisobutyronitrile, a peroxide such as penzoyl peroxide, a peracid ester such as t-butyl perbenzoate,
A redox system consisting of ammonium persulfate or the like and an iron salt can be used. Furthermore, it is possible to introduce some unsaturated groups into such an emulsifier, and these unsaturated groups can participate in the copolymerization reaction during the emulsion polymerization described later, resulting in a more stable aqueous polymer dispersion. can be obtained.

As a method for introducing an unsaturated group into the emulsifier, for example, a part of the carboxyl group in the copolymer is reacted with glycidyl methacrylate or glycidyl acrylate in the presence of a basic catalyst, so that a methacrylic group or an acrylic group can be introduced into the emulsifier. can be introduced into the copolymer side chain. After distilling off an appropriate amount of the organic solvent from the copolymer solution obtained in this way under normal pressure or reduced pressure, the copolymer is neutralized by at least 50% of the carboxyl groups by adding a basic substance. The emulsifier used in the present invention can be obtained by diluting it with water to a desired concentration.

In this case, the amount of neutralization is preferably 70% or more, and the basic substances used for neutralization include ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, dimethylethanolamine, diethanolamine, and triethanol. There are amines, etc. In the present invention, an aqueous polymer dispersion, which is the object of the present invention, can be obtained by emulsion polymerizing a monomer mixture containing an epoxy resin using such an emulsifier.

Epoxy resins present in emulsion polymerization include:
Epicoat-828-1001, 1004-10
07, 1009, etc. [product name manufactured by Shell Chemical Co., Ltd.],
Or epicron - 80 stops - 1010, - 301 -
1000 etc. [Product name manufactured by Dainippon Ink and Chemicals Co., Ltd.]
Bisphenol type epoxy resins such as epoxy resins can be mentioned, and the amount thereof is suitably 5 to 3% by weight based on the total amount of the monomer mixture to be emulsion polymerized. The presence of an epoxy resin during emulsion polymerization significantly improves the water resistance and chemical resistance of the coating film, but if the epoxy resin is less than 5% by weight, almost no such effects are observed, and 3. If it exceeds % by weight, the stability of the resulting aqueous polymer dispersion will be poor and the mechanical properties of the coating film will be impaired. Further, the monomer mixture to be emulsion polymerized in the presence of an epoxy resin to obtain the aqueous polymer dispersion consists of compound '11 used as the third component of the emulsifier and a pinyl monomer, and compound '1 ) is suitably between 5 and 5% by weight, preferably between 5 and 3% by weight, based on the total amount of epoxy resin and monomer mixture.

If the amount of compound '1} is less than 5% by weight, the object of the present invention, which is to obtain a coating film with markedly improved mechanical properties, water resistance, and chemical resistance, cannot be achieved, and the weight of compound '1} is less than 5% by weight. If it exceeds %, the mechanical properties and water resistance of the coating film will deteriorate. Furthermore, as vinyl monomers in the monomer mixture, monomers used as monoethylene unsaturated monomers collectively referred to as the fourth component of the aforementioned floating L agent, acrylic acid, methacrylic acid, acrylic acid hydroxy Examples include alkyl, hydroxyalkyl methacrylate, and the like.

The vinyl monomer is present in an amount of 20 to 9% by weight based on the total amount of the epoxy resin and the monomer mixture. If it exceeds %, the curability decreases, which is not preferable.
The aqueous polymer dispersion of the present invention is prepared by mixing compound '11 with a vinyl monomer in the presence of an epoxy resin.

Then, if necessary, the solution is supplemented to 40 to 80 qo to make a uniform solution, and then added to the aqueous solution of the emulsifier and carried out according to the usual emulsification method. In this case, a monomer mixture containing the above emulsifier and epoxy resin. The appropriate weight ratio of the former to the latter is 5 to 40:95 to 60 in terms of solid content. The aqueous polymer dispersion thus obtained has excellent mechanical stability, thermal stability, and good storage stability, and is the thermosetting polymer composition targeted by the present invention. Even when the aqueous polymer dispersion is used alone, it is possible to obtain a baked coating film with significantly improved mechanical properties, water resistance, and chemical resistance, which is the objective of the present invention. If an amino resin is blended and used, these effects will become even more remarkable.

Amino resins with various structures are used, but
For example, di-, tri-, tetra-, besotar, or hexamethylolmelamine and its derivatives, urea-
formaldehyde condensate, urea-melamine cocondensation resin,
Examples include benzobuanamine, but melamine resin is particularly preferred. The blending ratio of the aqueous polymer dispersion and the amino resin legs is 100 to 60 in terms of solid content ratio.
%, B' is less than 40%, especially when the wind is 100-70%
The range of 'B' is preferably 30% or less. A blend outside this range will result in defects in coating film performance such as water resistance and solvent resistance, making it impossible to achieve the object of the present invention. The aqueous polymer dispersion according to the present invention has an affinity for pigments, and other known water-reducing resins as pigment dispersants are not particularly required. It may be added in a proportion of up to 5 parts by weight based on the solid content.

One of the features of the compositions according to the invention is that the proportion of organic solvents in the volatile substances can be between 3 and 3% by weight. If the amount of organic solvent is within this range, there will be no problem in preventing air pollution. Here, volatile substances have a boiling point of 300 oo at normal pressure.
It refers to the following substances, specifically water and organic solvents. The composition of the present invention may contain various inorganic and organic pigments, various fillers, additives, and the like, as required.

As a method for coating the composition of the present invention, various well-known coating methods such as brush coating, immersion coating, spray coating, roller coating, or mist coating can be used.

The composition of the present invention is usually heat-cured after coating, and the heat-curing conditions vary depending on the content of crosslinkable functional groups in the composition, film thickness, type of solvent, etc., but are usually 80 to 250°C, preferably 10 at a suitable temperature in the temperature range of 100 to 18 pi○
By heating for ~60 minutes, a coating film with excellent water resistance and solvent resistance can be formed.

In addition, in advance, a normal crosslinking catalyst such as NAC1, NH4NQ, (N5)2HP04, (COOH)2, p-toluenesulfonic acid is added to the composition at a concentration of 0% relative to the solid content of the composition.
．． 5-1. It is also possible to add % by weight of the compound, which is effective for lowering the heat curing conditions.

The present invention is characterized by not only using a self-crosslinking monomer during emulsion polymerization in the production of an aqueous polymer dispersion, but also using a self-crosslinking monomer in the emulsifier itself. If an amino resin is blended with the solution alone or with the aqueous polymer dispersion to form a film in the presence or absence of a crosslinking catalyst and then heat-treated, it will be possible to form a film between the emulsifiers, between the polymers, between the emulsifier and the polymer, and even between the emulsifiers and the polymers. Because a dense three-dimensional network structure is formed between the dispersed particles and the external crosslinking agent (amino resin), it is possible to obtain a coating with high water resistance, chemical resistance, and good mechanical properties. Since emulsion polymerization is carried out in the presence of the coating, it is not only more effective in improving the coating performance described above, but also significantly improved adhesion (including interlayer adhesion) and salt spray resistance. Furthermore, since the amount of organic solvent in the volatile matter is small, the viscosity of the solution is reduced in current aqueous paints, making it significantly more effective in preventing air pollution than the current use of large amounts of organic solvents. The above-mentioned effects obtained by adding an epoxy resin can also be sufficiently obtained with a general aqueous solution type paint system, but in that case, it is difficult in practice due to poor storage stability. A composition with excellent storage stability can only be obtained by coexisting the polymer dispersion during the production of the polymer dispersion.

When unmodified epoxy resin, that is, epoxy resin with oxirane groups, is blended with general water-soluble resin varnish,
Since the varnish is an alkaline aqueous solution, it has extremely poor stability due to the opening reaction of the oxirane group, and precipitates and separates, making it virtually impossible to use it in a denatured state. In the present invention B, the epoxy resin exists within the neutral acrylic resin particles and has good stability as it does not come into direct contact with the alkaline aqueous solution. In addition, during film formation, the epoxy resin is mixed with the acrylic emulsion particles, homogenized, and reacts with the carboxyl group of the dispersion stabilizer to form a strong bond. In this case, the effect will be significant. Furthermore, the effects obtained by the present invention in comparison with conventional emulsion polymerization methods and aqueous solution type coatings will be explained as follows.

First, in paints obtained by conventional emulsion polymerization methods, surfactants remain in the paint film, so the water resistance and weather resistance of the paint film are unsatisfactory, and the gloss is also poor.

However, in the preparation of the composition according to the invention, the above-mentioned disadvantages are not present, since no conventional surfactants are used and the particle size of the resulting aqueous polymer dispersion is extremely small. In addition, conventional aqueous paints require a large amount of carboxyl groups to make the base resin water-soluble, and these remain in the paint film, resulting in poor alkali resistance, water resistance, and weather resistance.

On the other hand, the aqueous polymer dispersion of the present invention requires only a small amount of carboxyl groups relative to the total amount, so that the above-mentioned drawbacks hardly occur. Furthermore, it is now possible to increase the non-volatile content during painting, which is limited by current aqueous paints.
Paint workability is also improved. The present invention will be explained below with reference to Examples and Comparative Examples. Example 1 Hydroxyethyl methacrylate 5 parts by weight acrylic acid
2 parts by weight styrene
4 parts by weight ethyl methacrylate
35 parts by weight azobisisobutyronitrile
1 part by weight was dropped into 10 parts by weight of cellosolve heated to 12,020 ℃ to carry out a copolymerization reaction over 7 hours, then part by weight of the solvent 7 was distilled off, neutralized with triethylamine, and water was added. was added to make a 15% aqueous solution.

Add methyl methacrylate to 10 parts by weight of this aqueous solution.
2 parts by weight, ethyl acrylate 1
A mixture consisting of 5 parts by weight of N-poxymethylacrylamide, 3 parts by weight, and 1 part by weight of Epiquat 828 was mixed to form a homogeneous solution. After stirring for 1 hour, 1 part by weight of ammonium persulfate was added to 5 parts by weight of water. When added to the solution and heated at 7yo for 4 hours, the solid content was 45.
% and a viscosity of 105 centipoise.

The obtained dispersion did not change in viscosity even after being left at 40:00 for one month, and was stable without any aggregates. 1 part by weight of 16 boxes of this aqueous polymer dispersion was added to 1 part by weight of methylated methylolmelamine.
Seed HM-100 (80% butyl cellosolve solution)
[Product name manufactured by Sumitomo Chemical Co., Ltd.] 37 parts by weight and 10 parts by weight of Butyl Cellosol were added to make a paint, diluted with water, and mixed with food cup #4 for 3 rounds, resulting in a solid content of 35.
%, and the amount of organic solvent in the volatile matter was 11%. When this was spray-coated on an iron plate and competed at 140 oo for 30 minutes, a coating film with good physical properties, particularly adhesion, acid resistance, alkali resistance, solvent resistance, water resistance, and salt spray resistance, was obtained. Example 2 20 parts by weight of the aqueous polymer dispersion obtained in Example 1 was added with Reuban 2 E (
A paint was prepared by adding parts by weight of 50% n-butyl/xylol mixed solution (trade name, manufactured by Mitsui Toatsu Chemical Co., Ltd.) 1 and parts by weight of butyl cellosolve 2, and diluted with water to make a food cup #. The solid content was 36%, and the amount of organic solvent in the volatile matter was 17%.

When this was spray-painted on a steel plate and baked at 14,000 for 30 minutes, the physical properties, especially adhesion, acid resistance, alkali resistance,
A coating film with excellent solvent resistance, water resistance, and salt spray resistance was obtained. Example 3 Hydroxyethyl methacrylate 1 part by weight Acrylic acid 8 parts by weight Styrene
4 parts by weight ethyl methacrylate
42 parts by weight azobisisobutyronitrile
2 parts by weight were dropped into 10 parts by weight of cellosolve heated to 120 pm C, and the copolymerization reaction was carried out over 7 hours, after which 8 parts by weight of the solvent was distilled off and neutralized with triethylamine. Add water to make a 25% aqueous solution.

Using 80 parts by weight of this aqueous solution, titanium white JR-60 female [
Teikoku Kako Co., Ltd. product name] 10 parts by weight were dispersed in a ball mill, and the polymer aqueous dispersion 1 used in Example 1 was dispersed into this.
A paint was prepared by adding 1 part by weight of a tablet and 3 parts by weight of HM-100, diluted with water, and tested in a #4 food cup.The solid content was 52%, and the amount of organic solvent in the volatile matter was 8%. there were. When this was spray-painted on an iron plate, it had excellent coating workability, and when it was left to stand at 140°C for 30 minutes, it showed excellent physical properties, especially adhesion, acid resistance, alkali resistance, solvent resistance, water resistance, and salt spray resistance. A coating film with good gloss was obtained. Example 4 5 parts by weight of aluminum pigment was added and dispersed with 8 parts by weight of the 25% aqueous solution used in Example 3, and 11 parts by weight of the aqueous polymer dispersion 11 used in Example 1 and HM-100 were added thereto. 30
A paint was prepared by adding 10 parts by weight of butyl cellosolve, diluted with water, and filtered through a #4 food cup three times to find that the solid content was 35% and the amount of organic solvent in the volatile matter was 12%.

When this was spray-painted on an iron plate, the coating workability was excellent, and when baked at 140℃ between three powders, the physical properties were improved, especially adhesion, acid resistance, alkali resistance, solvent resistance, and water resistance.
Excellent salt spray resistance, excellent metallic feel,
A coating film with good gloss was obtained. Example 5 Hydroxyethyl acrylate 25 parts by weight Hydroxypropyl methacrylate 5 parts by weight methacrylic acid
1 part by weight N-methylolacrylamide 1 part by weight Methyl methacrylate 2 parts by weight
1 part by weight of butyl acrylate 3 parts by weight azobisisobutyronitrile 1 part by weight was added dropwise to 10 parts by weight of inpropyl alcohol heated to reflux, and polymerization was carried out over 7 hours. Part by weight of was distilled off, neutralized with aqueous ammonia, and water was added to make a 20% aqueous solution.

Styrene is added to 10 parts by weight of this aqueous solution.
la weight part isoptyl methacrylate
3 parts by weight of Epiclone 1010 3 parts by weight of N-butoxymethylmethacrylamide were heated at 6030° C. to form a homogeneous solution, and then added to 1.
After standing for an hour, 1 part by weight of potassium persulfate was dissolved in 1 part by weight of water, and the mixture was heated at 75° C. for 4 hours to obtain an aqueous polymer dispersion having a solid content of 36% and a viscosity of 200 centipoise.

The obtained dispersion did not change in viscosity even after being left at 40 qo for one month, and was stable without any aggregates. A paint was prepared by adding 5 parts by weight of butyl cellosol to 10 parts by weight of this polymer aqueous dispersion, diluted with water, and mixed with a #4 food cup.
When the actual product was filtered, the solid content was 32%, and the amount of organic solvent in the volatile matter was 16%. Spray paint this on a steel plate and heat it to 140℃.
After baking for 30 minutes, the physical properties, especially adhesion, acid resistance,
A coating film with excellent alkali resistance, solvent resistance, water resistance, and salt spray resistance was obtained. Example 6 Hydroxypropyl acrylate 4 parts by weight N-butoxymethylacrylamide 2 parts by weight acrylic acid
5 parts by weight methyl methacrylate
35 parts by weight azopisisobutyronitrile 1
Part by weight was added dropwise to 10 parts by weight of Cellosol which had been heated to 120°C and polymerized for 7 hours, followed by 2 parts by weight of glycidyl methacrylate and hydroquinone.
0.05 parts by weight of dimethylaminoethanol and 0.5 parts by weight were added, and heating was continued for an additional 6 hours.

Parts by weight of Solvent 7 were distilled off from this solution, neutralized with triethylamine, and then diluted with water to make an 8% aqueous solution. Styrene is added to 10 parts by weight of this aqueous solution.
4 male parts by weight N-propoxymethylacrylamide 1 part by weight N-methylolmethacrylamide 1 part by weight Epiquat 1001 4 parts by weight n-dodecyl mercaptan 0.1 part by weight was heated and stirred at 60 qo to form a homogeneous solution, and then added. After praying for 1 hour, dissolve 1 part by weight of ammonium persulfate in 1 part by weight of water and add 7 parts by weight.
When heated at 5q0 for 4 hours, the solid content was 44% and the viscosity was 90.
A centipoise polymer dispersion was obtained.

This dispersion did not change in viscosity even after being left at 40° C. for one month, and was stable without any aggregates. A paint was prepared by adding 37 parts by weight of HM-100 and 1 part by weight of butyl cellosolve to 159 parts by weight of this aqueous polymer dispersion, diluted with water and strained in a #4 food cup for 3 times, resulting in a solid content of 36%.
The amount of organic solvent in the volatile matter was 9%. When this was spray-painted on an iron plate and allowed to harden at 140 qo for 30 minutes, the physical properties were as follows.
In particular, coating films with excellent adhesion, acid resistance, alkali resistance, solvent resistance, water resistance, and salt spray resistance were noted. Comparative Example 1 In Example 1, except that the components added to 10 parts by weight of the 15% aqueous solution (emulsifier) were replaced with "33 parts by weight of thyl methacrylate, 24 parts by weight of ethyl acrylate, and 3 parts by weight of N-butoxymethylacrylamide". An aqueous dispersion was prepared in the same manner as in Example 1.

Comparative Example 2 In Example 1, 15% aqueous solution (emulsifier)
An aqueous dispersion was prepared in the same manner as in Example 1, except that among the components added to 100 parts by weight, "3 parts by weight of N-butoxymethylacrylamide" was replaced with "3 parts by weight of hydroxyethyl methacrylate". did.

Performance test results Table 1 shows the performance test results of the coating film (thickness: 20 mm) that was spray-coated with the aqueous dispersions obtained in the above Examples and Comparative Examples on an iron plate and heated at 14,000 Celsius for 30 minutes. .

Table 1 Test Methods Gloss: Determined visually Hardness: Performed according to the pencil scratch test specified in JIS K5400-614.

Adhesion: Use a sharp knife to reach the substrate (iron plate).
After making 100 goblets of size 1 x 1 on the paint film, pasting adhesive cellophane tape on the surface, and rapidly peeling off the tape, the number of paint films remaining on the substrate.

Acid resistance: 0. The condition of the coated surface was observed after immersion in an aqueous hydrochloric acid solution at room temperature for 48 hours. Alkali resistance: 0. The condition of the coated surface was observed after immersion in an aqueous sodium hydroxide solution at room temperature for 4 hours.

Solvent resistance: The state of the coated surface was observed after soaking in 20qo xylene for 4 hours. Water resistance: The state of the painted surface was observed after being immersed in tap water at 40:00 for one week.

Salt spray resistance: The coating film was cross-cut to reach the substrate, and after being left in a salt water mist tester for one week, rust formation from the cut portion was examined.

Claims (1)

[Scope of Claims] 1 (A) 5 to 60% by weight of hydroxyalkyl acrylate and/or hydroxyalkyl methacrylate, 5 to 20% by weight of acrylic acid and/or methacrylic acid,
Compounds represented by the following general formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In the formula, R is a hydrogen atom or a methyl group, R' is a hydrogen atom, or C_nH_2_n_+_1, where n is an integer from 1 to 4.) (I) is 20% by weight or less, and the monoethylenically unsaturated monomer copolymerizable with these is 90% by weight or less, and the total amount of the compound (I) and the monoethylenically unsaturated monomer is A water-soluble copolymer obtained by copolymerizing and neutralizing monomer components consisting of 20% by weight or more is used as an emulsifier, 5 to 30% by weight of an epoxy resin,
5 to 50% by weight of the compound (I) and vinyl monomer 2
A thermosetting coating composition consisting essentially of an aqueous polymer dispersion prepared by emulsion polymerization of a monomer mixture containing 0 to 90% by weight of an epoxy resin. 2 Applicable (A
) by adding (B) an amino resin to a polymer aqueous dispersion,
The ratio of (A) and (B) is (A) 100 in terms of solid content weight ratio.
The thermosetting coating composition according to claim 1, wherein (B) is 40% or less relative to 60%.