JPH0329807B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-dispersible resin component useful as a resin component for a chipping-resistant material used as a coating material for protecting the exterior sheet metal part of a vehicle, such as an automobile, from scratches caused by flying stones. Although it can form a coating film and has a thin film thickness, it has excellent chipping resistance, excellent adhesion to sheet metal parts, rust prevention, flat thin film formation, sound insulation, gasoline resistance, cold flexibility, and resistance. The present invention relates to a water-dispersible resin component that is extremely useful for providing chipping-resistant materials exhibiting various properties such as impact resistance, especially non-solvent type chipping-resistant materials. More specifically, the present invention relates to the following (a) to (c) (a) polymerizable monomers containing no carboxyl group in the molecule, and whose homopolymer has a glass transition temperature of 0°C. The above polymerizable monomers...
...1 to 25% by weight (b) A polymerizable monomer that does not contain a carboxyl group in its molecule and whose homopolymer has a glass transition temperature of less than 0°C...
...70 to 98% by weight, and (iii) α,β-unsaturated carboxylic acid...0.5 to 5% by weight. Glass transition temperature obtained by copolymerizing a polymerizable monomer consisting of 0.5 to 5% by weight under emulsion polymerization conditions. The present invention relates to a water-dispersible resin for chipping-resistant materials comprising a water-dispersible resin having a temperature of 0°C or less. It can be applied to sheet metal processing parts, especially plating plates, such as lead-tin alloy plated steel plates, tin plated steel plates, aluminum plated steel plates, chrome plated steel plates, nickel plated steel plates, and various other alloy plated steel plates, etc., to provide a thin coating. Although it can form a film and has a thin film thickness, it has excellent chipping resistance, excellent adhesion to sheet metal parts, rust prevention, flat thin film formation, soundproofing, gasoline resistance, cold flexibility, and impact resistance. It is desired to develop a chipping-resistant material, especially a non-solvent type chipping-resistant material, which exhibits various properties such as hardness. Conventionally used protective coatings called anti-chip materials have some degree of anti-chip effect when applied in a high film thickness on exposed galvanized steel surfaces or electrodeposited coatings. However, the anti-chip effect at a thin film thickness is unsatisfactory, and furthermore, the anti-rust effect of the protective coating alone is extremely poor, especially in the case of water-based anti-chip material compositions. However, there is a disadvantage that rust occurs in a short period of time in exposed steel surfaces such as scratches and seams during sheet metal processing, and a solution to this problem has been strongly desired. Further, the coating film of conventional chipping-resistant materials has irregularities, and there is a concern that they are susceptible to scratches when a flying stone hits the recessed portions. Further, in the case of aqueous chipping-resistant material compositions, there is a concern about the adhesion after immersion in water, especially immediately after immersion, and improvement thereof has also been desired. The inventors of the present invention have discovered that the present inventors have achieved excellent performance in applications for chipping-resistant materials that are useful as resin components for water-based chipping-resistant materials that are non-solvent type and can avoid environmental pollution caused by solvent volatilization, and in particular for rust-proof and chipping-resistant materials. Research has been conducted to provide a water-dispersible resin component that exhibits the following properties. As a result, the following (a) to (c) (a) Polymerizable monomers containing no carboxyl group in the molecule and whose homopolymer has a glass transition temperature of 0°C or higher. Sexual monomer...
...1 to 25% by weight, (b) A polymerizable monomer that does not contain a carboxyl group in its molecule and whose homopolymer has a glass transition temperature of less than 0°C. …
...70 to 98% by weight, and (iii) α,β-unsaturated carboxylic acid...0.5 to 5% by weight. Glass transition temperature obtained by copolymerizing a polymerizable monomer consisting of 0.5 to 5% by weight under emulsion polymerization conditions. It has been discovered that a water-dispersible resin having a temperature of 0° C. or less has extremely excellent performance and suitability as a resin component for a non-solvent water-based chipping-resistant material. According to the research of the present inventors, the above specific (a) and (b)
The glass transition temperature obtained by copolymerizing a polymerizable monomer consisting of a specific range of amounts under emulsion polymerization conditions is 0.
The water-dispersible resin below ℃ can form a thin, flat coating film even in the form of a chipping-resistant material containing other additives such as fillers and pigments, and has a thin film thickness. Excellent chipping resistance, excellent adhesion to sheet metal parts, rust prevention, soundproofing,
It has the ability to form a film exhibiting various properties such as gasoline resistance, cold flexibility, and impact resistance, and has been found to be extremely useful as a water-dispersible resin component for water-based rust-proofing and chipping-resistant materials. Ta. Furthermore, it is important to use the above three types of monomers (a), (b) and (c) in combination and to satisfy their usage ratios, especially omitting (c) α,β-unsaturated carboxylic acid. As a result, the stability of the water-dispersible resin for chipping-resistant materials decreases, causing a change in viscosity, which tends to lead to a state where it cannot be coated. It was found that this deteriorated the adhesion to the plated steel plate and the rust prevention properties. Furthermore, if the glass transition point temperature of the resin is higher than 0°C, there is a problem that the chipping resistance becomes poor. It was found that it is particularly important to use monomers (a), (b), and (c) in combination and to satisfy their usage ratios. Therefore, an object of the present invention is to provide a water-dispersible resin component for chipping-resistant materials. The above objects and many other objects and advantages of the present invention will become more apparent from the following description. Examples of the polymerizable monomer (a) that can be used to form the water-dispersible resin for the chipping-resistant material of the present invention include styrene, methylstyrene, ethylstyrene, methyl acrylate, methyl methacrylate,
Ethyl methacrylate, butyl methacrylate,
Acrylonitrile, vinyl acetate, vinyl chloride, acrylamide, N-methylol acrylamide, diacetone acrylamide, diallyl phthalate, divinylbenzene, triallyl cyanurate, glycidyl acrylate, glycidyl methacrylate, hydroxymethyl methacrylate, hydroxy methacrylate, etc. Can be mentioned. Preferably styrene, methyl acrylate, methyl methacrylate, acrylonitrile, N-methylol acrylamide, acrylamide,
diallyl phthalate, divinylbenzene, triallyl cyanurate, glycidyl methacrylate, etc., and these polymerizable monomers (a) do not contain a carboxyl group in the molecule, and these polymerizable monomers are not polymerized. It is essential that the glass transition temperature of the homopolymer obtained is 0°C or higher. Examples of the polymerizable monomer (b) include alkyl acrylates having an alkyl group of 2 or more carbon atoms, such as ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate. , butyl or octyl ester of maleic acid or fumaric acid, vinyl propionate, vinyl vasatuccinate, vinylidene chloride, etc., but preferably ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc. are used. These polymerizable monomers (b) must not contain carboxyl groups in their molecules, and the glass transition temperature of the homopolymer obtained by polymerizing these polymerizable monomers must be less than 0°C. That is. Furthermore, examples of the polymerizable monomer (c) include maleic acid, fumaric acid, crotonic acid, acrylic acid, methacrylic acid, itaconic acid, etc., but preferably acrylic acid, methacrylic acid, itaconic acid. α,β-unsaturated carboxylic acids such as As mentioned above, in the present invention, two or more types of polymerizable monomers (a) and (b) whose respective homopolymers have different glass transition temperatures, and an α,β-unsaturated carboxylic acid ( A water-dispersible resin having a glass transition temperature of 0° C. or less obtained by blending c) in a specific ratio and emulsion polymerization is used as a resin component for the chipping-resistant material. Only by utilizing this resin component can excellent adhesion and chipping resistance, as well as improved rust prevention properties, be obtained. Furthermore, improvements in thin, flat coating film formation, gasoline resistance, cold flexibility, impact resistance, etc. can be obtained. The use of the water-dispersible resin of the present invention as a resin component for chipping-resistant materials has not been previously known. The water-dispersible resin for rust-proofing and chipping-resistant materials of the present invention contains 1 to 25% by weight, preferably 1 to 15% by weight, more preferably 1 to 10% by weight of the polymerizable monomer (a). The polymerizable monomer (b) is 70 to 98% by weight, preferably 75 to 98% by weight, more preferably 80 to 95% by weight, and the α,β-unsaturated carboxylic acid (c) is
It can be obtained by emulsion polymerization of a combination of polymerizable monomers comprising 0.5 to 5% by weight, preferably 0.5 to 4% by weight, more preferably 0.5 to 3% by weight.
Each of these monomers (a), (b) and (c) can be used singly or in combination of two or more types,
When using multiple types, it is sufficient that the total amount satisfies the usage ratio of each monomer described above. monomer
If the usage ratios of (a), (b), and (c) are exceeded, the adhesion to the plated steel sheet, especially the adhesion after water immersion and the rust prevention ability will deteriorate, which is not desirable. Furthermore, the chipping resistance effect is also adversely affected. For example, if (c) α,β-unsaturated carboxylic acid is omitted, the stability of the water-dispersible resin for the chipping-resistant material decreases, and the viscosity of the chipping-resistant material changes, making it easy to become uncoatable. Furthermore, the adhesion of the chipping-resistant coating film to various types of galvanized steel sheets and rust prevention properties also tend to deteriorate. Moreover, (c) if the amount of α,β-unsaturated carboxylic acid is too excessive, the adhesion of the chipping-resistant coating film to the steel plate after immersion in water tends to decrease. Therefore, (iii) the α,β-unsaturated carboxylic acid monomer is selected in an amount of 0.5 to 5% by weight, preferably 0.5 to 4% by weight, more preferably 0.5 to 3% by weight. Furthermore, (a) if the amount of monomer used is too small,
The chipping resistance, which is the original objective, decreases. Furthermore, if the amount of monomer (a) used is too excessive, the chipping-resistant coating film will have poor cold flexibility and impact resistance, and the effects of the present invention will not be obtained. Therefore, (a) the monomer is selected in an amount of 1 to 25% by weight, preferably 1 to 15% by weight, more preferably 1 to 10% by weight. Furthermore, (b) if the amount of monomer used is too small,
There is a problem in that the chipping-resistant coating film tends to have poor cold flexibility and impact resistance. Furthermore, (b) if the monomer is used in an excessive amount, the adhesion of the chipping-resistant coating film to a steel plate after immersion in water, chipping resistance, and rust prevention properties will deteriorate. Therefore, (b) the monomer is selected in an amount of 70 to 98% by weight, preferably 75 to 98% by weight, more preferably 80 to 95% by weight. Furthermore, the water-dispersible resin for chipping-resistant materials of the present invention contains a polymerizable monomer mixture consisting of a specific amount ratio of the specific polymerizable monomers (a), (b), and (c) as described above. It is a water-dispersible resin obtained by emulsion polymerization, and its glass transition temperature is 0°C or lower. If the glass transition temperature exceeds 0° C., the chipping resistance becomes poor, which is not preferable. In the present invention, the glass transition temperature of the homopolymer of the polymerizable monomer (a) and the glass transition temperature of the homopolymer of the polymerizable monomer (b) forming the water-dispersible resin are determined by differential thermal analysis. The glass transition temperature (hereinafter abbreviated as Tg) of the polymer of each of these monomers is exemplified as shown in Table 1.

[Table] In addition, the glass transition temperature (Tg) of the water-dispersible resin obtained is calculated according to the following formula. Tg calculation formula 1/Tg=W ₁ /Tg ₁ +W ₂ /Tg ₂ +...+W _o /Tg _o Tg and Tg _o are expressed as absolute temperatures. W _o indicates the weight fraction of each component monomer of the polymer. The Tg of the polymer of each monomer is shown in Table 1 above. The water-dispersible resin component for chipping-resistant materials of the present invention includes monomer components (a), (b), and (c) that satisfy the above-mentioned combination of specific types of monomers and the proportions of each monomer. It can be formed by copolymerizing under emulsion polymerization conditions. The emulsion polymerization technique itself can be performed by a known method. Emulsion polymerization can be carried out in an aqueous medium in the presence of a catalyst and in the presence of a surfactant and/or a protective colloid. Examples of surfactants to be used include:
Fatty acid salts such as sodium oleate and potassium oleate, alkyl sulfate ester salts such as sodium lauryl sulfate and ammonium lauryl sulfate, alkylaryl sulfonates and dialkyl sulfosuccinates such as sodium alkylbenzenesulfonate and sodium alkylnaphthalene sulfonate. , alkyl phosphates, and a wide range of anionic surfactants such as nonionic anionic surfactants with polyoxyalkylenes such as polyoxyethylene added; for example,
Polyoxyalkylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyalkylene alkyl phenol ethers such as polyoxyethylene octyl phenol ether and polyoxyethylene nonyl phenol ether; and polyoxyethylene higher alcohols. Ethers, sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, polyoxyalkylene fatty acid esters such as polyoxyethylene monolaurate, polyoxyethylene monostearate, oleic acid monoglyceride Examples include a wide range of nonionic surfactants such as glycerin fatty acid esters such as stearic acid monoglyceride, and oxyethylene oxypropylene block polymers. These can be used alone or in combination. Examples of protective colloids to be used include partially saponified polyvinyl alcohol, completely saponified polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose salts, and salts thereof, guar gum. Natural polysaccharides such as
These can be used alone or in combination. During emulsion polymerization, it is preferable to use a surfactant and a protective colloid as exemplified above in combination, from the viewpoint of stability of the system during polymerization. Further, if desired, a small amount of a cationic surfactant or an amphoteric surfactant can be used in combination with an anionic and/or nonionic surfactant such as those exemplified above. Examples of such cationic surfactants include alkylamine salts such as laurylamine acetate, quaternary ammonium salts such as lauryltrimethylammonium chloride and alkylbenzyldimethylammonium chloride, and cationic surfactants such as polyoxyethylalkylamine. Examples include activators. Examples of amphoteric surfactants include amphoteric surfactants such as alkyl betaines such as lauryl betaine. Furthermore, examples of catalysts used in emulsion polymerization include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate, tertiary butyl hydroperoxide, cumene hydroperoxide, paramenthane hydroperoxide, and the like. Examples include organic peroxides such as, hydrogen peroxide, and the like.
These can also be used either singly or in combination. Further, during emulsion polymerization, a reducing agent may be used in combination, if desired. Examples include reducing organic compounds such as ascorbic acid, tartaric acid, citric acid, and glucose, sodium thiosulfate, sodium sulfite, sodium bisulfite, and sodium metabisulfite. The reaction temperature can be selected as appropriate, but for example, about 40 to
Examples include temperatures such as about 90°C. During the reaction,
Although it is possible to add the entire amount of a given surfactant to the reaction system in advance, it is also possible to add a portion of the surfactant to the reaction system in advance to start the reaction, and then add the remainder continuously or in portions at intervals during the reaction. It is also possible and preferred. Furthermore, monomers (a), (b), and (c) can be added all at once, added in portions, or added continuously, but it is preferable to add them continuously in order to control the reaction. . In addition to the above-mentioned surfactant and catalyst, a PH regulator, polymerization degree regulator, antifoaming agent, etc. can be added as appropriate during emulsion polymerization. The water-dispersible resin for chipping-resistant materials of the present invention, which can be produced as described above, usually has a non-volatile content of about 30 to
The non-volatile content should be about 70% by weight, preferably about 40 to about 65%. The viscosity of the resin is approximately
A viscosity of 10,000 cps or less, for example about 5 to about 10,000 cps, can be exemplified. After emulsion polymerization, the pH of the resulting water-dispersible resin liquid is preferably adjusted to 3-11 using a PH regulator such as ammonia or triethanolamine. Furthermore, it is preferable to add an antifoaming agent, a preservative, etc. When using the water-dispersible resin for chipping-resistant materials of the present invention obtained as described above as a resin component of chipping-resistant materials, other water-dispersible resins such as styrene-butadiene rubber latex, etc. may be used as desired. Butyl rubber latex, vinyl acetate emulsion, vinyl acetate copolymer emulsion,
Polyurethane aqueous dispersion, nitrile-butadiene rubber latex, etc. may be mixed, but the solid content should be about 30% by weight or less based on the water-dispersible resin component of the present invention. When using the water-dispersible resin for chipping-resistant material of the present invention as a chipping-resistant material, known fillers can be appropriately selected and used. Examples of fillers include talc, calcium carbonate, diatomaceous earth, mica, kaolin, barium sulfate,
Examples include magnesium carbonate, erosil, vermiculite, graphite, alumina, silica, rubber powder, etc. Coloring agents such as titanium oxide and carbon black may also be used. These fillers are preferably used in a proportion of 70 to 250 parts by weight based on 100 parts by weight of the solid content of the water-dispersible resin. If the amount is less than 70 parts by weight, problems such as blistering may occur during baking, drying and hardening, which is not preferable. Also, the blending amount is 250
If the amount is less than 1 part by weight, in addition to the problem of reduced adhesion after immersion in water, the chipping resistance of the material is significantly reduced, and block-like peeling may occur especially when exposed to impact from large flying stones at low temperatures, which is undesirable. . The rust-proof and chipping-resistant material that can be used in the present invention can form a flat protective coating without uneven appearance, and can exhibit excellent chipping resistance even with a thin film thickness. It is not desirable to mix asbestos fibers, which are designated as chemical substances and are suspected of being carcinogenic. Conventionally, in the case of chipping-resistant materials, especially water-based chipping-resistant materials, an elastic coating film is applied to the base coating surface or the finish coating surface, which has excellent rust prevention properties, to protect the coating surface from chipping. However, the main focus was placed only on the anti-corrosion properties of the chipping-resistant material itself, and no careful consideration was given to the rust-preventing ability of the chipping-resistant material itself. Prior to the present invention, there had been no proposal for a chipping-resistant material that also has the above-mentioned extremely excellent anti-corrosion properties. Furthermore, when the water-dispersible resin for chipping-resistant material of the present invention is used as a chipping-resistant material, it is preferable to use a non-toxic rust-preventing pigment. Conventionally, anti-corrosion pigments that have been widely used in oil-based paints and anti-rust base paints, such as red lead, lead powder, zinc chromate, barium chromate, and strontium chromate, are toxic and do not interact well with water-dispersible resins. It is not preferable because the expected antirust effect cannot be realized under the combined use conditions of , and therefore it cannot be used in the present invention. The above-mentioned non-toxic rust-preventing pigments may be those called non-polluting rust-preventing pigments, such as; zinc phosphate, calcium phosphate, aluminum phosphate, titanium phosphate, silicon phosphate, or their orthos, and phosphate rust preventive pigments such as condensed phosphates; zinc molybdate, calcium molybdate, zinc calcium molybdate, zinc potassium molybdate, zinc potassium phosphomolybdate,
Examples include molybdate-based rust preventive pigments such as calcium potassium phosphomolybdate; borate-based rust preventive pigments such as calcium borate, zinc borate, barium borate, barium metaborate, and calcium metaborate; and the like. These toxic antirust pigments are mixed in an amount of 10 to 100 parts by weight, preferably 30 to 70 parts by weight, per 100 parts by weight of the solid content of the water-dispersible resin. If the amount of non-toxic anti-rust pigment is less than 10 parts by weight, sufficient anti-corrosion ability will not be achieved, and if the amount is too large (more than 100 parts by weight), it will not be possible to achieve sufficient rust prevention after immersion in water. This is not preferable because it reduces the adhesion of the material. The rust-proof and chipping-resistant material described above can further contain conventional additives such as preservatives, dispersants, thickeners, thixotropic agents, antifreeze agents, and PH adjusters. The properties of the rust-proof and chipping-resistant material are as follows:
For example, specific gravity is about 1.1 to about 1.5, pH is about 7 to about 9,
Preferred examples include properties in which the nonvolatile content is about 60% or more and the viscosity measured using a B-type viscometer is about 100 to about 300 poise. A method of protecting a sheet metal workpiece using the rust-proof and chipping-resistant material described above will be explained. Sheet metal processed parts may be steel plates, plated steel plates, painted steel plates, etc., processed into various shapes using a sheet metal press, and then welded together as automobile parts, such as gasoline tanks, and painted after welding. It may be a face. For example, the sheet metal processed parts that can be most effectively protected include gas tanks made of plated steel sheets, and other sheet metal parts outside the vehicle interior, such as the back of the car's floor, tire house, front apron, and rear apron. It can also be applied to electrodeposition coating surfaces, intermediate coating coating surfaces, top coating coating surfaces, etc. The coating method for application may be any conventionally known method, and airless coating is common. The dry film thickness of the rust-proof and chipping-resistant material preferred for protecting sheet metal parts is approximately 200 to approximately 800 microns.
More preferably about 200 to about 500 microns. If the dry film thickness is less than about 200 microns, it is not preferable because the chipping resistance rapidly decreases.
If the diameter is about 800 microns or more, it may cause blistering during baking and drying, which is not preferable. The rust-proofing and chipping-resistant material of the present invention can exhibit sufficient chipping resistance even when the dry film thickness is, for example, about 500 microns or less. preferable. The painted surface may be dried at room temperature or by baking, but preferably after pre-drying at about 80℃.
It is preferable to apply heat in a drying oven at a temperature of 120 to about 180°C. When using the water-dispersible resin for chipping-resistant materials of the present invention as a resin component of chipping-resistant materials, various fillers, pigments, preservatives, dispersants, thickeners, thixotropic agents, antifreeze agents, etc., which are known per se, may be used. Additives such as agents, pH regulators, etc. can be added as appropriate. Examples of manufacturing the water-dispersible resin for chipping-resistant materials of the present invention will be shown below. Example 1 In a 5 liter round bottom flask with a stirrer, add 1050 ml of water.
g, polyoxyethylene nonyl phenyl ether 7g, sodium dodecylbenzenesulfonate 3g
and heat at 40℃ to dissolve. After replacing the inside of the flask with nitrogen, the temperature inside the flask is raised to 80°C. 80
Styrene (glass transition temperature 90°C)
℃) 288g, 2-ethylhexyl acrylate (glass transition temperature -60℃) 1594g, acrylic acid 38
mixture of g, 2.5% ammonium persulfate aqueous solution 160
g, 160 g of a 2.5% aqueous sodium bisulfite solution, 70 g of polyoxyethylene nonyl phenyl ether, and 670 g of an aqueous solution in which 30 g of sodium dodecylbenzenesulfonate were dissolved, respectively, were continuously added over 7 hours for emulsion polymerization. The obtained emulsion polymer was a milky white emulsion with a glass transition temperature of -43 DEG C. and a solid content of about 51%, and the pH was adjusted to 7.0 with aqueous ammonia to obtain water-dispersible resin A for chipping-resistant materials of the present invention. Comparative example 1 Water 1050 in a 5 liter round bottom flask with a stirrer
g, polyoxyethylene nonyl phenyl ether 7g, sodium dodecylbenzenesulfonate 3g
and heat at 40℃ to dissolve. After replacing the inside of the flask with nitrogen, the temperature inside the flask is raised to 80°C. 80
Styrene (glass transition temperature 90°C)
℃) 760g, 2-ethylhexyl acrylate (glass transition temperature -60℃) 1053g, acrylic acid 114
mixture of g, 2.5% ammonium persulfate aqueous solution 160
g, 160 g of a 2.5% aqueous sodium bisulfite solution, 70 g of polyoxyethylene nonyl phenyl ether, and 670 g of an aqueous solution in which 30 g of sodium dodecylbenzenesulfonate were dissolved were each continuously added over 7 hours for emulsion polymerization. The obtained emulsion polymer was a milky white emulsion with a glass transition point of -9°C and a solid content of about 51%, and the pH was adjusted to 7.0 with aqueous ammonia to obtain a water-dispersible resin B for comparison. Reference Examples 1 and 2 A water-dispersible resin for chipping-resistant materials of the present invention (resin A obtained in Example 1) and a comparative water-dispersible resin (resin B obtained in Comparative Example 1) were used, respectively. ,
Chipping-resistant materials having the formulations shown in Table 1 below were prepared, and the tests described below were conducted. The results are shown in Table 1 below. Secondary adhesion test after water-resistant immersion After cleaning the surface of a 0.8 x 100 x 200 mm lead-tin alloy plated steel plate (product name Tansheet) manufactured by Nippon Steel Corporation with thinner, each sample was sprayed with airless spray (compression The coating was applied at a ratio of 30:1 and a primary pressure of 3Kg/ ^m2 to a dry film thickness of approximately 350μ using a tip with a diameter of approximately 0.9mm, and then baked at 140°C for 20 minutes to form a chipping-resistant coating. A test plate was prepared by forming a film. The prepared test plate was immersed in water at approximately 40℃ for 7 days, then pulled out, the water on the paint film was gently wiped off with gauze, and the water on the paint film was held vertically at room temperature for 4 to 7 hours, and then the water on the paint film was removed with gauze. Wipe off lightly, JIS-
In accordance with K-5400 6.15, make a 1 mm wide goblin and check the adhesion rate of the paint film by peeling it off with cellophane tape. Rust Prevention Test Two tan sheets similar to those described above were seamlessly welded, the surfaces of the plates were cleaned with thinner, and each sample was coated on both sides using the same coating method as described above to prepare test plates. The prepared test plate is JIS-Z-2371
It was subjected to a salt spray test according to the following. Chipping resistance test A nut (M-6) was continuously dropped from a height of 2 m at an angle of 60 degrees using a PVC pipe with a diameter of 40 mm onto the painted surface of a test plate prepared in the same manner as the secondary adhesion test. The weight was evaluated based on the total weight that fell when the substrate was exposed. However, three levels of film thickness were used: 300μ, 450μ, and 800μ.

【table】

【table】

【table】

Claims (1)

[Scope of Claims] 1 The following (a) to (c): (a) A polymerizable monomer that does not contain a carboxyl group in its molecule, and a homopolymer of the monomer has a glass transition temperature of 0. Polymerizable monomer whose temperature is above ℃...
...1 to 25% by weight, (b) A polymerizable monomer that does not contain a carboxyl group in its molecule and whose homopolymer has a glass transition temperature of less than 0°C. …
...70 to 98% by weight, and (iii) α,β-unsaturated carboxylic acid...0.5 to 5% by weight. Glass transition temperature obtained by copolymerizing a polymerizable monomer consisting of 0.5 to 5% by weight under emulsion polymerization conditions. A water-dispersible resin for chipping-resistant materials consisting of a water-dispersible resin with a temperature of 0°C or less.