JPH0665525A - Copolymer latex for chipping-resistant baking paint - Google Patents

Abstract

PURPOSE:To obtain a copolymer latex excellent in chipping resistance and water resistance by emulsion-polymerizing a monomer mixture comprising a conjugated diene, an ethylenically unsaturated acid, and other monomer using an organic peroxide. CONSTITUTION:A monomer mixture comprising 20-80wt.% conjugated diene, 0.1-15wt.% ethylenically unsaturated acid, and 5-79.9wt.% other copolymerizable monomer is emulsion-polymerized in the presence of an organic peroxide to obtain the copolymer latex having a toluene-insoluble content of 50wt.% or higher. This latex imparts excellent film-forming properties, crack resistance, adhesion strength, blistering resistance, chipping resistance, and water resistance to a chipping-resistant baking paint. In particular, the chipping resistance and water resistance are on levels unable to be attained with any conventional copolymer latex known as a material for this use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolymer latex used for baking type chipping-resistant paints, and more particularly to baking type chipping-resistant paints having film-forming properties, crack resistance,
The present invention relates to a copolymer latex that imparts adhesion, chipping resistance and water resistance.

[0002]

Baking type anti-chipping paint is a paint which is applied to the surface of metal or plastic and then baked and dried at high temperature to form a coating film, which effectively protects the surface from chipping. Such paint is generally called (baking type) anti-chipping paint. For example, the surface of a gasoline tank mounted on an automobile is plated with a lead-tin alloy to prevent rusting. However, while the automobile is running, the plated surface may be damaged (chipping) due to the impact of pebbles that have been flipped up. When chipping occurs, the gasoline tank will be corroded by the rust generated from the damaged part.

As a means for preventing such chipping, it is known to apply a chipping resistant coating and form a coating film to protect the surface. The chipping-resistant paint is composed of a composition containing a polymer component and a filler component as essential essential components, and solvent-based chipping-resistant paint and water-based bake-type chipping paint are known. In recent years, due to pollution problems such as environmental pollution, fire hazard, and hygiene problems during work, the change from solvent-based to water-based is progressing, and as the switching progresses, it is required to improve the performance of water-based bake-type chipping resistant paint. Is increasing.

[0004]

The required properties of the water-based, baking-type, chipping-resistant paint include film-forming property, crack resistance, adhesion, blister resistance, chipping resistance and water resistance. Baking-type chipping-resistant paints using a conventional copolymer latex do not have sufficient performances, and particularly have poor chipping resistance and water resistance. This chipping resistance and water resistance are the essential and extremely important performances of the baking type chipping resistant coating. The present invention, bake-type chipping resistant coating, imparts excellent chipping resistance and water resistance effect that cannot be obtained with conventional copolymer latex known for bake-type chipping resistant coating,
It is another object of the present invention to provide a copolymer latex which also has excellent film-forming property, crack resistance, and adhesion.

[0005]

The present invention comprises 20 to 80% by weight of a conjugated diene monomer and 0.1 to 1 ethylenically unsaturated acid.
5% by weight and other copolymerizable monomer 5 to 79.9% by weight
To provide a copolymer latex for a baking resistant chipping resistant coating, characterized in that the monomer consisting of (1) is not polymerized in the presence of an organic peroxide, and the content of the toluene insoluble matter in the copolymer is 50% by weight or more. It is a thing. Hereinafter, the present invention will be described in detail.

Specific examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-neopentyl-1, 3-butadiene, 2-chloro-1,3
-Butadiene, 1,2-dichloro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, 2-bromo-1,3-butadiene, 2-cyano-1,3-butadiene, substituted straight chain There are conjugated pentadienes, linear and side chain conjugated hexadienes, and the like, and 1,3-butadiene is particularly preferable. The conjugated diene monomer is 20 to 80% by weight, preferably 30 to 75% by weight. If it is less than 20% by weight, the film forming property and crack resistance are inferior, while if it exceeds 80% by weight, the chipping resistance is inferior.

Specific examples of the above-mentioned ethylenically unsaturated acid monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, fumaric anhydride, maleic acid and maleic anhydride. Vinyl sulfonic acid,
Examples thereof include ethylenically unsaturated sulfonic acids such as isoprene sulfonic acid. The ethylenically unsaturated acid monomer may be neutralized with an alkali metal such as sodium or potassium or ammonia. It is preferably an ethylenically unsaturated carboxylic acid. The ethylenically unsaturated acid monomer is 0.1 to 15% by weight, preferably 0.5 to
It is 10% by weight. If it is less than 0.1% by weight, the adhesion will be
The chipping resistance is inferior, while if it exceeds 15% by weight, crack resistance and blister resistance are inferior.

Examples of the copolymer monomer other than the conjugated diene and the ethylenically unsaturated acid include, for example, aromatic vinyl monomers, (meth) acrylic acid ester monomers and vinyl cyanide monomer. Polymer, ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomer, ethylenically unsaturated carboxylic acid amide monomer, ethylenically unsaturated sulfonic acid ester monomer, ethylenically unsaturated alcohol monomer and esters thereof Examples thereof include a monomer, an ethylenically unsaturated ether monomer, an ethylenically unsaturated amine monomer, an ethylenically unsaturated silane monomer, and a vinyl halide monomer. These may be used alone or Used in seeds and above. Preferred are aromatic vinyl-based monomers, (meth) acrylic acid ester monomers, and vinyl cyanide-based monomers. Aromatic vinyl monomers are more preferred.

Examples of the aromatic vinyl compound include styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene and 4-hydroxystyrene.
Ethylstyrene, 4-ethoxystyrene, 3,4-dimethylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chloro-3-methylstyrene, 4-t-butylstyrene, 2,4-dichlorostyrene, 2, 6-dichlorostyrene, 1-vinylnaphthalene, divinylbenzene and the like can be mentioned, and styrene is particularly preferably used. Further, divinylbenzene is a crosslinkable monomer, and the toluene insoluble content can be adjusted by adjusting the amount of divinylbenzene used.

Specific examples of the acrylic acid ester monomer include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, acrylic acid 2 Examples include ethylhexyl, octyl acrylate, n-nonyl acrylate, isononyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, n-amine acrylate, lauryl acrylate, benzyl acrylate and cyclohexyl acrylate. be able to. Among these, alkyl acrylates having an alkyl group having 4 to 12 carbon atoms are preferable, and ethyl acrylate and acrylic acid n are more preferable.
-Butyl and isononyl acrylate, particularly preferably n-butyl acrylate.

Specific examples of the methacrylic acid ester monomer include methyl methacrylate, ethyl methacrylate,
N-butyl methacrylate, isobutyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, decyl methacrylate, undecyl methacrylate, Examples thereof include dodecyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, lauryl methacrylate, benzyl methacrylate, cyclohexyl methacrylate and the like. Among these, alkyl methacrylate having an alkyl group having 4 to 12 carbon atoms is preferable.

Specific examples of the vinyl cyanide-based monomer include acrylonitrile, α-chloroacrylonitrile, α-methoxyacrylonitrile, methacrylonitrile, α-chloromethacrylonitrile, α-methoxymethacrylonitrile and vinylidene cyanide. And the like, and of these, acrylonitrile is preferable.
Specific examples of the ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomer include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate.

Specific examples of the ethylenically unsaturated carboxylic acid amide monomer include acrylamide, methacrylamide, N-butoxymethyl acrylamide, N-butoxymethyl methacrylamide, N-butoxyethyl acrylamide and N-butoxyethyl methacrylamide. , N-
Methoxymethylacrylamide, N-methoxymethylmethacrylamide, Nn-propoxymethylmethacrylamide, Nn-propoxymethylmethacrylamide, N-methylacrylamide, N-methylmethacrylamide, N, N-dimethylacrylamide, N, Examples thereof include N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide and the like.

Specific examples of the ethylenically unsaturated sulfonic acid ester monomer include alkyl vinyl sulfonate,
Examples thereof include alkyl isoprene sulfonate. Specific examples of the ethylenically unsaturated alcohol monomer and ester monomers thereof, allyl alcohol, methallyl alcohol, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl stearate, vinyl benzoate, allyl acetate, Examples thereof include methallyl caproate, allyl laurate, allyl benzoate, vinyl alkyl sulfonate, allyl alkyl sulfonate, vinyl aryl sulfonate, and the like. Specific examples of the ethylenically unsaturated ether monomer include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, methyl allyl ether, ethyl allyl ether and the like.

Specific examples of the ethylenically unsaturated amine monomer include vinyldimethylamine, vinyldiethylamine, vinyldiphenylamine, allyldimethylamine and methallyldiethyleneamine. Specific examples of the ethylenically unsaturated silane monomer include vinyltriethylsilane, methylvinyldichlorosilane, dimethylallylchlorosilane, vinyltrichlorosilane and the like. Specific examples of the vinyl halide monomer include vinyl chloride, vinylidene chloride, 1,2-dichloroethylene, vinyl bromide,
Examples thereof include vinylidene bromide and 1,2-dibromoethylene.

The amount of the copolymerizable monomer other than the conjugated diene and the ethylenically unsaturated acid monomer is 5 to 79.5% by weight, preferably 15 to 69.5% by weight. The average particle size of the copolymer latex of the present invention is preferably 0.04 to 0.
4 μm, more preferably 0.5 to 0.35 μm. If it is less than 0.04 μm, the blister resistance is insufficient, while if it exceeds 0.4 μm, the adhesion and chipping resistance may be insufficient. The average particle diameter of the copolymer latex here was taken as the average particle diameter by taking the number average of 100 particles with an electron microscope. Regarding the average particle size of the above-mentioned copolymer latex, the type and amount of emulsifier at the time of polymerization, the amount of water for polymerization, the stirring speed, the seed polymerization method, and the like are appropriately adjusted, or the desired average particles are combined appropriately. A copolymer latex having a diameter can be obtained. The toluene insoluble content of the copolymer latex is 50% by weight or more, preferably 55 to 98% by weight. If it is less than 50% by weight, water resistance and blister resistance are poor. The toluene insoluble content of the copolymer latex here is measured by the following method.

When the copolymer latex is used alone or in combination with sodium hydroxide or potassium hydroxide, p
Adjust to H8 and solid content 48%. This copolymer latex is applied to a Teflon plate using a 200 μ applicator and then quickly dried. The solid content Ag of the completely dried coating film was collected and immersed in 50 ml of toluene at room temperature for 20 hours. 2 Filter using qualitative filter paper. A part (C milliliter) of the filtrate is accurately sampled and evaporated to dryness, the obtained residual solid content Bg is weighed, and the toluene insoluble content is determined by the following formula. [AB (100 / C)] / A × 100% = toluene insoluble matter

Regarding the toluene insoluble content of the above-mentioned copolymer latex, the kind and amount of the crosslinkable monomer used at the time of polymerization, the kind and amount at the start, the kind and amount of the chain transfer agent, the polymerization temperature, etc. are appropriately selected. It is possible to obtain a desired copolymer latex having a toluene insoluble content by adjusting the amount or by appropriately combining these.

The copolymer latex of the present invention can be obtained by emulsion polymerization in the presence of an organic peroxide which is a polymerization initiator. By using this organic peroxide, the copolymer latex excellent in chipping resistance and water resistance, which is the object of the present invention, can be obtained. The organic peroxide that can be used in the present invention is not particularly limited, but preferable organic peroxides include hydroperoxide, diacyl peroxide and the like. Examples of hydroperoxides include t-butyl peroxide, cumene hydroperoxide, di-isopropylbenzene hydroperoxide, paramenthane hydroperoxide, and 2,5-dimethylhexane 2,5.
-Dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide and the like.

Examples of the diacyl peroxide include octanoyl peroxide, lauroyl peroxide and benzoyl peroxide.
Hydroperoxide is more preferable, cumene hydroperoxide, di-isopropylbenzene hydroperoxide, and paramenthane peroxide are particularly preferable. The organic peroxides listed above can be used alone or in combination of two or more. Further, an inorganic initiator such as potassium persulfate, ammonium persulfate, hydrogen peroxide, or an azo initiator such as azobisisobutyronitrile may be used in combination within a range that does not hinder the object of the present invention.

In the present invention, the amount of organic peroxide used is
It is preferably 0.03 to 25, based on the total amount of the monomer components.
%, More preferably 0.03 to 2% by weight, particularly preferably 0.05 to 1% by weight. In order to promote emulsion polymerization, for example, sodium pyrobisulfite,
Sodium sulfite, sodium bisulfite, ferrous sulfate, glucose, formaldehyde sodium sulfoxylate, L-ascorbic acid and its salts, reducing agents such as sodium bisulfite: combined use of chelating agents such as glycine, alanine and sodium ethylenediaminetetraacetate You can also do it.

The copolymer latex of the present invention can be obtained by emulsion-polymerizing the above-mentioned monomer components using the above-mentioned organic peroxide, a known emulsifier and a chain transfer agent. Here, as the emulsifier, anionic emulsifiers such as sodium dodecylbenzene sulfonate, sodium lauryl sulfate, sodium diphenyl ether disulfonate, and sodium succinate dialkyl ester sulfonate,
Alternatively, nonionic emulsifiers such as polyoxyethylene alkyl esters and polyoxyethylene alkyl allyl ethers, amphoteric emulsifiers, fluorine-based surfactants and the like can be mentioned, and one or more of these can be used in combination. The amount of the emulsifier used is preferably 0.1 to 10% by weight, more preferably 0.2 to 5% by weight, particularly preferably 0.2 to 3% by weight based on the total weight of the monomer components.
% By weight. Within this range, a copolymer latex having excellent polymerization stability and further excellent effects as the object of the present invention can be obtained.

As the chain transfer agent, α-methylstyrene dimer, terpinolene, α-terpinene, γ-terpinene, dipentene, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, diethylxanthogen disulfide. , Dimethyl quintogen disulfide, diisopropyl xanthogen disulfide, tetramethyl thiuram monosulfide, tetraethyl thiuram disulfide, tetrabutyl thiuram disulfide, dipentanemethyl thiuram disulfide and the like can be used.
These are usually used in an amount of 0 to 15% by weight based on the total weight of the monomer components.

In emulsion polymerization, in addition to the emulsifier, polymerization initiator, chain transfer agent, etc., various electrolytes, pH adjusters, etc. may be used in combination, if necessary. And
Usually, 100 parts by weight of the monomer component is added to 100 parts of water.
To 300 parts by weight and the emulsifier, polymerization initiator, chain transfer agent, etc., in an amount within the above range, the polymerization temperature is 10 to 90.
C., preferably 30 to 80.degree. C., and the polymerization time is 5 to 40 hours. The method for adding the monomer component is not particularly limited, and any method such as a batch addition method, a continuous addition method or a divided addition method may be employed. The final polymerization conversion rate of the copolymer latex is preferably 60 to 100%, particularly preferably 95 to 100%. The solid content of the copolymer latex of the present invention is 48
˜58 wt%, more preferably 50-56 wt%.

The bake-type chipping-resistant paint is mainly composed of a copolymer latex and a filler, and if necessary, a heat-sensitive additive such as a fibrous filler or a delayed coagulant, carbon black, an organic pigment or the like. Color pigments, rust prevention pigments,
Additives such as a dispersant, a defoaming agent and a thickener, an organic solvent such as ethylene glycol, propylene glycol and butyl cellosolve may be contained. The composition ratio of the copolymer latex and the filler in the baking-type chipping-resistant coating is generally 10 to 400 parts by weight, and preferably 2 to 100 parts by weight (solid content) of the copolymer latex.
The amount is 0 to 300 parts by weight, more preferably 30 to 250 parts by weight. When a fibrous filler is used in combination, if necessary, the amount is preferably 5 to 100 parts by weight with respect to 100 parts by weight (solid content) of the copolymer latex in order to sufficiently exert the effect of addition.

Specific examples of the filler include talc, calcium carbonate, mica, kaolin, barium sulfate, graphite, aluminum hydroxide, alumina, iron oxide, titanium oxide, silica, rubber powder, glass talk, and at least the surface of which is porous. Examples thereof include those containing silicon dioxide as a main component, for example, non-fibrous fillers such as diatomaceous earth, which may be used alone or in combination of two or more kinds. Of these powdery fillers, diatomaceous earth and aluminum hydroxide are particularly preferred. For diatomaceous earth, SiO
₂ is contained in an amount of 80% by weight or more, and aluminum hydroxide is 80% by weight of Al ₂ (OH) _3.
The above is contained. Further, hollow particles such as silica balloons, glass balloons, carbon balloons, polyvinylidene chloride balloons, polystyrene balloons and the like can be mentioned. The preferable average particle size of these fillers is 1 to 300 μm.

The fibrous filler used as necessary is not particularly limited as long as it is in a fibrous form, and for example, carbon fiber, rock wool, fibrous potassium titanate, fibrous magnesium sulfate, Examples thereof include attabalgite, wollastonite, fibrous barium sulfate, asbestos and pulp. The solid content of the baking type chipping resistant coating is usually 60 to 85% by weight,
It is preferably 65 to 80% by weight. By using the copolymer latex of the present invention in the baking type chipping resistant coating,
It imparts excellent film-forming properties, crack resistance, adhesion, blister resistance, chipping resistance, and water resistance to baking type bitching-resistant paints, and the points of particular note are the effects of chipping resistance and water resistance. This is an effect that cannot be obtained with the copolymer latex conventionally known for baking type and chipping resistant coatings.

[0028]

The present invention will be further described below with reference to examples, but the present invention is not limited to these examples. In the examples, parts and% are based on weight. Method for producing copolymer latex A to C and a to F In a reactor, the monomer components shown in Tables 1 and 2, an emulsifier, and a chain transfer agent are charged and heated under nitrogen gas with stirring. When the internal temperature reaches 30 ° C, the initiator component is added and the polymerization temperature 35
To 60 ° C., and the polymerization time is appropriately in the range of 15 to 30 hours, and the copolymer latexes A to C shown in Tables 1 and 2 and a to
I got it. A to C are copolymer latexes within the scope of the present invention, and a to C are copolymer latexes outside the scope of the present invention.

Examples 1 to 3 and Comparative Examples 1 to 6 Using the copolymer latexes shown in Tables 1 and 2, bake-type chipping-resistant paints were evaluated. The evaluation results are shown in Table 1 and Table 2.
Shown in. Evaluation method (1) Preparation of baking resistant chipping resistant coating (a) Copolymer latex of Tables 1 and 2 (solid content) 100 parts (b) Sodium hexametaphosphate (dispersant) 1.5 (c) Defoaming agent KM-71 ^Note 0.5 (d) Calcium carbonate (Super # 2000) ^{Note 3)} 200 (e) Water Amount to adjust solid concentration of 75% Note 1) Shin-Etsu Chemical Co., Ltd. Note 2) Average particle size 5 μm Manufactured by Maruo Calcium Co., Ltd. Components (a), (b), and (e) are put into a mixer, (d) is gradually added with stirring, and the mixture is sufficiently stirred to burn with a solid content concentration of 75%. A mold chipping-resistant paint was obtained, and the chipping-resistant paint was evaluated by the test method shown below.

(2) Evaluation of Baking-type Chipping Resistant Paint Test Example 1 (Evaluation of Chipping Resistance) Baking-type chipping-resistant paint was applied to a turn sheet plate (lead-tin plated steel plate) by an airless spray device.
Applied on top. Then, after leaving at room temperature for 10 minutes, 1
Each coating composition was cured by baking and drying at 00 ° C. for 10 minutes and further at 130 ° C. for 20 minutes to form a coating film having a thickness of 200 μm on the turn sheet plate. The formed coating films were evaluated for chipping resistance. As an evaluation method, first, a vinyl chloride pipe having an inner diameter of 20 mm was arranged so as to extend at an angle of 60 degrees with respect to the turn sheet plate on which the coating film was formed, and then an M4 nut from the height of 2 m was used. It was carried out by continuously dropping the coating film through the pipe and measuring the total weight (kg) of the M4 nut when the base material of the turn sheet plate was exposed. The results are shown in Tables 1 and 2.

Test Example 2 (Evaluation of Water Resistance) The turn sheet plate having the coating film with a thickness of 200 μm formed in Test Example 1 was allowed to stand for 1 week in warm water at 40 ° C., taken out, and kept as it was. Using the turn sheet plate of
The chipping resistance was measured in the same manner as in Test Example 1.
The results are shown in Tables 1 and 2. Test Example 3 (evaluation of blister resistance) In the same manner as in Test Example 1, a baking-type chipping-resistant paint was applied and baked to dry, and a film thickness of 1,0 was formed on the turn sheet plate.
A coating film having a thickness of 00 μm was formed, and the occurrence of swelling was observed for each coating film. The results are shown in Tables 1 and 2. ◯: There is no blistering on the coating film surface. X: The coating film surface has blisters. Test Example 4 (Evaluation of Film Formability) The coating film formation process of Test Example 3 was visually evaluated according to the following evaluation criteria. The results are shown in Tables 1 and 2. ◯: There is no unevenness on the coating film surface. X: The surface of the coating film is significantly uneven.

Test Example 5 (Evaluation of Adhesion) The adhesion was measured in accordance with the cross-cut tape method of JIS K5400 item 8.5. The results are shown in Table 1. Test Example 6 (Evaluation of Crack Resistance) A baking-type chipping-resistant paint was applied and baked and dried in the same manner as in Test Example 1 to give a film thickness of 1,0 on the turn sheet plate.
A coating film having a thickness of 00 μm was formed, and cracks and cracks were observed in each coating film. The results are shown in Tables 1 and 2. ◯: There is no crack or crack on the coating film surface. X: The coating film surface has cracks and cracks.

Examples 1 to 3 relate to baking type chipping-resistant paints using the copolymer latex within the scope of the present invention, and the copolymer latex of the object of the present invention can be obtained. Comparative Examples 1 and 2 are examples of copolymer latexes obtained by using an initiator outside the scope of the present invention, and are inferior in chipping resistance and water resistance. Comparative Example 3 is an example of a copolymer latex in which the amount of 1,3-butadiene used is less than the range of the present invention, and film forming property, chipping resistance, and crack resistance are poor. Comparative Example 4 is an example of a copolymer latex in which the amount of 3-butadiene used exceeds the range of the present invention, and the chipping resistance is poor. Comparative Example 5 is an example of a copolymer latex in which the amount of the ethylenically unsaturated acid used is less than the range of the present invention, and the adhesion and chipping resistance are poor. Comparative Example 6 is an example in which the toluene insoluble content of the copolymer latex is less than the range of the present invention, and the blister resistance and water resistance are poor.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

EFFECT OF THE INVENTION The copolymer latex for bake-type chipping-resistant paint of the present invention has excellent film-forming property, crack resistance, adhesion, blister resistance, chipping resistance, and water resistance for bake-type chipping-resistant paint. Give. Particularly noteworthy effects are chipping resistance and water resistance, and these effects are
This is an effect that cannot be obtained with the copolymer latex known for bake-type chipping resistant paints.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Yonekawa 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] 1. A conjugated diene monomer of 20 to 80% by weight,
Copolymer in which a monomer comprising 0.1 to 15% by weight of an ethylenically unsaturated acid and 5 to 79.9% by weight of another copolymerizable monomer is not polymerized in the presence of an organic peroxide. Is a copolymer latex for baking resistant chipping resistant coatings, wherein the toluene insoluble content is 50% by weight or more.