JP2519367B2 - Resin composition for electrodeposition paint - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for a matte electrodeposition coating having durability.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed as a method for matting the surface of an electrodeposition coating film. For example, by mixing an inorganic transparent pigment in the electrodeposition coating, the resin for coating and the inorganic transparent pigment are simultaneously deposited on the coated surface by electrodeposition coating,
How to deluster. A method in which an amino acid having a sulfonic acid group and a sulfuric acid ester group is added to an amino resin-curable anionic electrodeposition coating composition to make it matte by electrodeposition coating (JP-A Nos. 52-137444 and 52- 1374
45, 52-137446, and 56-1.
06977, JP-A-3-139574).
Then, a resin for coating is copolymerized with an unsaturated alkoxysilane compound to prepare an amino resin curing type (Japanese Patent Publication No.
No. 24519, Japanese Unexamined Patent Publication Nos. 2-255871 and 3-160074) are proposed.

However, among the above methods, the method of adding an inorganic transparent pigment involves a large difference in the specific gravity of the inorganic transparent pigment in an electrodeposition paint bath, so that process control such as indispensable stirring of the bath is required for uniformity. It is difficult to stabilize the degree of matting. In addition, the method of adding an organic acid to the amino resin-curable anionic electrocoating material makes it difficult to control the process in the bath of the electrocoating material because of differences in the electrophoretic velocity and the deposition characteristics between the coating resin and the acid. Becomes In addition, the resin composition for electrodeposition paints obtained by copolymerizing an unsaturated alkoxysilane compound does not have the above-mentioned problem, but the three-dimensional siloxane bond has an amino resin because of the chemical reaction originated from the hydrolysis of the alkoxysilane. Using a phenomenon that occurs in the resin particles for electrodeposition coatings containing, to make the coating a fine rough surface, the aim is to provide a matte effect due to diffused reflection of light, but due to changes over time in the gel content, etc. It is difficult to obtain a consistently rough surface.
Matting degree control is a problem.

In order to solve the above problems, the present inventors first prepared an aqueous dispersion of a block copolymer containing a polysiloxane residue in the main chain and a carboxyl group in the side chain. Proposed an electrodeposition paint as the main component (Japanese Patent Application No. 3)
No. 338498, Japanese Patent Application No. 3-346384). Furthermore, the present inventors have previously proposed an electrodeposition coating composition containing, as a main component, an aqueous dispersion of a graft copolymer containing a polysiloxane residue and a carboxyl group in its side chain (Japanese Patent Application No. 4-1).
3346). These electrodeposition paints have excellent durability and high matte performance, but their drawback is that the variable range of both performances is relatively narrow.

[0005]

When the matte coating process is performed by the electrodeposition method, not only the matte degree but also the weather resistance, the roughness and opacification of the coated surface, the adhesion, the hardness, etc. There are also important evaluation items, which are greatly influenced by the composition and structure of the synthetic resin that constitutes the electrodeposition coating. Even in the case of the polysiloxane residue-containing block copolymer at the most advanced position in the above-mentioned prior art, or even the graft copolymer, each of them alone can always satisfy the above-mentioned requirements in many items. It cannot be provided. Therefore, it is an object of the present invention to provide a resin composition for an electrodeposition coating material, which can solve the above-mentioned problems and can cope with a wide range of required performances.

[0006]

According to the present invention, there is provided a resin composition for electrodeposition coating which can achieve the above object.

That is, according to the present invention, (A) a block copolymer containing a polysiloxane residue in the main chain and an acid residue in the side chain, and (B) a polysiloxane residue and an acid in the side chain. The present invention relates to a resin composition for electrodeposition coating, which comprises both components of a graft copolymer containing a residue as an aqueous dispersion.

The block copolymer having a polysiloxane residue in the main chain of the component (A) and an acid residue in the side chain is used for preparing the resin composition for electrodeposition coating composition of the present invention. , For example, Japanese Patent Application No. 3-338498 or 3-3
No. 46384, a carboxylic group (-) is formed in the presence of a compound in which an azo group and a polysiloxane residue are linearly bonded.
COOH), sulfuric acid (-OSO ₃ H), sulfonic acid (-SO
₃ H), phosphoric acid (—OPO ₃ H ₂ ), and the like, and a polymerizable unsaturated monomer containing an acid residue (hereinafter, simply referred to as an acid residue) and a polymerizable unsaturated monomer copolymerizable therewith. It is obtained by polymerizing in the presence of a radical polymerization initiator in a hydrophilic solvent. Therefore, the acid residue in the present invention is a carboxyl group,
It means a sulfuric acid group, a sulfonic acid group and a phosphoric acid group.

Examples of the compound in which an azo group and a polysiloxane residue are linearly bonded include those represented by the following general formula [I] or general formula [II].

Embedded image (In the formula, m is 0 or a number of 1 to 200, and n is 1 to
130 number) or

Embedded image (In the formula, m is 0 or a number of 1 to 200, and n is 1 to
240 numbers)

The acid residue-containing polymerizable unsaturated monomer, the polymerizable unsaturated monomer copolymerizable therewith, and the hydrophilic solvent used as the reaction solvent are the graft copolymer of the component (B) described below. The same materials as those described in the section of the combination can be used, and the method for producing the block copolymer can be performed in the same manner.

The graft copolymer containing a polysiloxane residue and an acid residue in the side chain of the component (B) used for preparing the resin composition for electrodeposition coating of the present invention is an unsaturated polysiloxane compound. And a polymerizable unsaturated acid monomer (a) containing an acid residue, and a polymerizable unsaturated monomer (b) copolymerizable therewith, the same hydrophilic solvent as in the synthesis of component (A) above. It is obtained by polymerizing in the presence of a radical polymerization initiator. The graft copolymer as the component (B) is synthesized, for example, as follows. The component giving a polysiloxane residue to the side chain is represented by the general formula [III]

Embedded image [In the formula, R ₁ represents hydrogen or a methyl group, R ₂ represents (CH ₂ ) ₁ (wherein, l is 0 or an integer of 1 to 6), R ₃ is the same or different, and a lower alkyl group, R ₄ Are the same or different and each is a halogen atom-substituted or unsubstituted alkyl group or phenyl group, A is an ester or amide bond, and n is 17 to 270]. Alkyl groups include, for example, methyl, ethyl, propyl, isopropyl, butyl, Te
1 to 6 carbon atoms such as rt-butyl, pentyl and hexyl groups
And a straight chain or branched alkyl group. Also,
The halogen atom-substituted alkyl group is a halogenated version of the above alkyl group, for example, chloromethyl, bromomethyl, trifluoromethyl, 2-chloroethyl, 3
-Chloropropyl, 3-bromopropyl, 3,3,3-
Examples include trifluoropropyl and 1,1,1,2-tetrahydroperfluorooctyl groups. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. The amount of unsaturated polysiloxane compound used is 2 to
If it is 30% by weight and the amount used is less than 2% by weight, there is almost no matting effect due to the copolymerization of the compound, and conversely 30% by weight.
If the amount exceeds 5% by weight, not only copolymerization with the components (a) and (b) becomes difficult but also uneconomical. The molecular weight of the unsaturated polysiloxane compound is 1,500 to 20,000.
And preferably 2,000 to 15,000. When the molecular weight is less than 1,500, there is almost no matting effect, and when it exceeds 20,000, copolymerization becomes difficult.

It goes without saying that the component (a) which gives an acid residue to the side chain is necessary for the process of making the resulting graft copolymer of the component (B) aqueous and for the electrodeposition coating process. Specific examples of the component (a) that can be used include (meth) acrylic acid,
Maleic acid, fumaric acid, itaconic acid, etc.
These can be used alone or in combination. The usable (a) component is acid phosphooxyethyl (meth) acrylate, acid phosphooxypropyl (meth) acrylate, acid phosphooxypolyoxyethylene glycol mono (meth) acrylate, acid phosphooxypolyoxypropylene glycol mono. Unsaturated organic phosphoric acid such as (meth) acrylate; unsaturated organic sulfonic acid such as vinyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and P-styrene sulfonic acid can be used, but especially ( Meta)
Acrylic acid is preferred. The amount of the component (a) used varies depending on the nature of the monomer to be copolymerized and the reaction conditions, but it is usually 15 to 150 in acid value, preferably 20 to 1
00.

Specific examples of the component (b) used in the production of the graft copolymer of the component (B) include (meth) acrylic acid esters having 1 to 8 carbon atoms, for example, methyl (meth) acrylate, Ethyl, isopropyl, n-butyl, isobutyl, 2-ethylhexyl, 2-hydroxyethyl, hydroxypropyl; vinyl esters of alkane monocarboxylic acids having 1 to 12 carbon atoms, such as vinyl acetate, vinyl propionate, vinyl-n. Butyrate, vinyl versatate; unsaturated amides or imides, eg
(Meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, alkoxymethyl (meth)
Acrylamide, such as N-butoxymethyl (meth) acrylamide, maleic imide, maleic diamide;
Vinyl aromatic monomers such as styrene and P-methylstyrene are exemplified. Incidentally, in general, any monomer can be used as the monomer of the present invention as long as it has a radically polymerizable monomer, and vinyl chloride, vinylidene chloride,
Halogen-containing vinyl compounds such as vinylidene fluoride; mono- or di-olefins such as ethylene and 1,3-butadiene; α, β-olefinically unsaturated acids such as esters of maleic acid and fumaric acid; and other (meth) acrylonitrile And so on. These monomers can be used alone or in combination. The total amount of component (a) and component (b) used is 70 to 98% by weight.

Specific examples of the hydrophilic solvent used for the graft copolymer include monoalcohols having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol,
Isobutyl alcohol and t-butyl alcohol; ethylene glycol and its derivatives, such as ethylene glycol monomethyl ether, monomethyl ether acetate, monoethyl ether, diethyl ether, monoethyl ether acetate, monoisopropyl ether, monobutyl ether, diethyl ether, monoethyl ether. Acetate, monoisopropyl ether, monobutyl ether acetate; diethylene glycol and its derivatives, such as monomethyl ether, monoethyl ether, monoethyl ether acetate, mono-n-butyl ether, mono-t- of diethylene glycol.
Butyl ether, dimethyl ether, methyl ethyl ether, diethyl ether monoacetate; triethylene glycol and its derivatives, such as triethylene glycol monomethyl ether, monoethyl ether; propylene glycol and its derivatives, such as propylene glycol monomethyl ether, monoethyl ether, mono -N-butyl ether, mono-t-butyl ether, methyl ether acetate; dipropylene glycol and its derivatives, such as dipropylene glycol monomethyl ether, monoethyl ether; tripropylene glycol and its derivatives, such as tripropylene glycol monomethyl ether; glycerin And its derivatives, for example glycerol monoacetate; trimethyleneglycol Le and derivatives thereof, for example, 1-butoxy - ethoxy propanol, 3,3-dimethyl-3
-Methoxypropanol; butanediol and its derivatives such as 3-methoxybutanol, 3-methyl-3
-Methoxybutanol, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-
Methyl-1,3-butanediol; acetylene glycol derivatives such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol and its ethylene oxide adduct, 2,6-dimethyl-4-octyne -3,6-diol; other dioxane, 1,5-pentanediol, hexylene glycol, trimethylolpropane,
Examples thereof include 1,2,6-hexanetriol and low-molecular-weight polyethylene glycol, and generally, monoalkyl ethers of ethylene glycol or propylene glycol and combinations thereof with a monoalcohol having 4 or less carbon atoms are preferable. These solvents can be used alone or in combination.

The polymerization initiator used in the graft copolymerization reaction may be a peroxide-type and / or azo-type radical polymerization initiator, and specifically, a peroxide-type initiator such as methyl ethyl ketone peroxide and methyl isobutyl ketone peroxide. Ketone peroxide;
Diacyl peroxides such as lauroyl peroxide, benzoyl peroxide and p-chlorobenzoyl peroxide; 2,4,4-trimethylpentyl-
Hydroperoxides such as 2-hydroperoxide, cumene hydroperoxide and t-butyl hydroperoxide; dicumyl peroxide, di-t
-Dialkyl peroxides such as butyl peroxide; butyl-4,4-di (t-butylperoxy) pentoate, peroxyketals such as ethyl-3,3-di (t-amylperoxy) butyrate; alkyl peresters A percarbonate and the like can be mentioned. In the azo system, for example, 2,2′-azobisisobutyronitrile, 1,1 ′
-Azobis (cyclohexane-1-carbonitrile) and other azonitriles; 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'azobis [2- (2-imidazolin-2-yl) propane], etc. Azoamidine and the like. It should be noted that these polymerization initiators may be combined with a reducing agent such as an organic amine to form a redox system.

Since the method for producing the graft copolymer as the component (B) is solution polymerization which is generally carried out, a known method can be adopted. That is, the method of charging the above-mentioned three components and the hydrophilic solvent may be batch charging or divided charging, and the reaction temperature is usually 60 to 140 ° C. and the reaction time is about 4 to 12 hours. If necessary, various chain transfer agents such as octyl mercaptan, lauryl mercaptan, β-mercaptopropionic acid, and octyl thioglycolate can be used for controlling the molecular weight.

The block copolymer of the component (A) and the graft copolymer of the component (B) obtained as described above are mixed in a desired ratio to prepare an aqueous dispersion, and the mixture is added to the mixture. This is done by adding a base such as ammonia and amines to neutralize the acid residues in the copolymers of the above-mentioned components (A) and (B), and then adding water thereto and stirring. As another method of preparing an aqueous dispersion, the block copolymer as the component (A) and the graft copolymer as the component (B) are separately added with a base such as ammonia or amines to obtain a copolymer. You may neutralize the acid residue in it, and after that, add water and stir to make a water dispersion, and mix each water dispersion. The mixing ratio of the block copolymer of the component (A) and the graft copolymer of the component (B) is not particularly limited,
Usually (A) component 95 to 5% by weight and (B) component 5 to 95
It can be used in the range of weight%.

Examples of amines include alkylamines such as diethylamine, triethylamine, diisopropylamine and trimethylamine; alkanolamines such as monoethanolamine, diethanolamine and triethanolamine; alkylalkanolamines such as diethylaminoethanol. Is usually 0.5 to 0.95 (molar ratio) with respect to the acid residue in the above copolymer.

The aqueous dispersion of the copolymer of the components (A) and (B) thus obtained can be used as an electrodeposition paint as it is, but a thermosetting amino resin is usually added.
That is, an initial condensate of formalin with melamine, urea, benzoguanamine, or the like, or an alkyl ether compound thereof with an aliphatic alcohol having 4 or less carbon atoms is blended as an amino resin to make the coating film tough. The amino resin may be added before or after forming the aqueous dispersion. The addition amount is in the range of 1/9 to 7/3 in weight ratio with respect to the above copolymer.

The operations from the above water dispersion to the addition of melamine resin and the like to finish as an electrodeposition coating are carried out individually for each of the block copolymer and the graft copolymer, and then by mixing them. Is also achieved.

[0021]

The present invention will be described in more detail with reference to Examples and Comparative Examples. The “parts” in the production examples, examples and comparative examples are “parts by weight” unless otherwise specified.

Production Example 1 A four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a calcium chloride tube was charged with a compound of the general formula [IV]

Embedded image Wherein, D is (CH _{2) l} or _{- (CH 2) 3 OCH 2} CH 2
-, E represent NH ₂ or OH, R ₂ is the same or different and represents a lower alkyl group, and R ₃ is the same or different and represents a halogen atom-substituted or unsubstituted alkyl group or a phenyl group. 1 represents the same or different and represents an integer of 0 or 1 to 6, and m represents an integer of 0 or 1 to 200], which is a polydimethylsiloxane having a molecular weight of 4,600 and having amino groups at both ends of the molecule. (General formula (I
V], R ₂ and R ₃ are methyl groups, E is —NH ₂ ,
D is _{- (CH 2) 3 -,} m is an average 60 a is Shin-Etsu Chemical Co., Ltd., X-22-161C) 100 parts was charged with 4.38 parts of triethylamine and chloroform 86.8 parts, was thoroughly stirred . Then, a solution consisting of 6.89 parts of 4,4′-azobis (4-cyanopentanoic acid chloride) and 86.8 parts of chloroform was added dropwise under ice cooling over 40 minutes. After completion of the dropwise addition, the mixture was reacted at room temperature for 2 hours, diluted with 50 parts of chloroform, washed with water to remove water-soluble components such as triethylamine hydrochloride, and dried under reduced pressure.

The number average molecular weight of the obtained azo group-containing polydimethylsiloxane amide was found to be 29.00 by GPC analysis.
It was 0. The decomposition temperature of the azo group determined by DSC (Differential Scanning Calorimeter) was 93.6 ° C, and the decomposition enthalpy was -39.3 mJ / mg, but the heat balance after heat treatment at 140 ° C for 5 hours was Didn't show up.

1 equipped with stirrer, heat exchanger and thermometer
In a 4,000 ml four-necked flask, 10 parts of the azo group-containing polydimethylsiloxane compound obtained above, 20 parts of ethylene glycol monomethyl ether, and butyl acrylate 35
Parts, 35 parts of methyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, and 10 parts of methacrylic acid were charged, and solution polymerization was performed under stirring at a temperature of about 100 ° C. for 7 hours, and then 21.5 parts of ethylene glycol monomethyl ether was added. Was added. The temperature of the reaction solution was then cooled to 60 ° C. and neutralized with 9.4 parts of triethylamine.

Next, 40 parts of an alkoxymethylmelamine resin (Nikalac MX-40: manufactured by Sanwa Chemical Co., Ltd.) as a curing agent and ethylene glycol monoethyl ether 1
After adding 0 part of the solution, 260 parts of deionized water was gradually added to make the solution water-based to obtain a stable fine particle dispersion.

The properties of the resulting aqueous dispersion were as follows: Solid content concentration 29.9%, polymerization rate 98.8%,
Viscosity 250 cp (at 30 ° C), pH 8.3, average particle size 2
60 μm.

Production Example 2 In a 500 ml four-necked flask equipped with a stirrer, a heat exchanger and a thermometer, 26 parts of ethylene glycol monomethyl ether, 35 parts of butyl acrylate, 35 parts of methyl methacrylate, and 2-hydroxy methacrylate. Ethyl 10 parts, methacrylic acid 10 parts and silaplane FM-0725
(In the general formula [III], R ₁ , R ₃ , and R ₄ are methyl groups, R ₂ is a propylene group, A is an ester bond, and n is about 131 (molecular weight about 10,000). Dimethyl siloxane: manufactured by Chisso Co., Ltd.) 10 parts and charged with azobisisobutyronitrile 0.7 while stirring.
After dissolving part, warm. When the temperature of the solution reached about 80 ° C. due to heating, the solution rapidly reacted. After 2 hours and 4 hours of reaction at about 90 ° C., 15.5 parts of an ethylene glycol monomethyl ether solution containing 0.5 part of azobisisobutyronitrile was added half by half.
After reacting for another 2 hours, the mixture was cooled to 60 ° C. and neutralized with 9.4 parts of triethylamine.

Next, 40 parts of an alkoxymethyl melamine resin (Nikalac MX-40: manufactured by Sanwa Chemical Co., Ltd.) as a curing agent and ethylene glycol monoethyl ether 1
After adding 0 part of the solution, 260 parts of deionized water was gradually added to make the solution water-based to obtain a stable fine particle dispersion.

The properties of the obtained aqueous dispersion were as follows. Solid content concentration 30.1%, polymerization rate 99.2%, viscosity 2,700 cp (at 30 ° C), pH 8.0, number average molecular weight 2
9,000, average particle diameter 310 μm.

Example 1 An electrodeposition coating composition containing a polysiloxane residue in the main chain and a carboxyl group in the side chain as the main component obtained in Production Example 1 and Production Example 2 The resulting side chains were mixed with a polysiloxane residue and an electrodeposition coating material containing a carboxyl group so that both copolymers would have a weight ratio of 9: 1,
Using this as an electrodeposition paint, a matte electrodeposition coating was applied to an aluminum plate under the following conditions, and its performance was evaluated. The results are shown in Table 1. A) Aluminum plate: JIS H4000 (A1050P) 1.5 × 35 × 70 mm b) Anodic oxidation: ・ Immersed in 10% NaOH aqueous solution for 2 minutes / 60 ° C., washed with deionized water ・ 15% HNO ₃ aqueous solution for 30 seconds / After soaking at 25 ° C, wash with deionized water ・ 15% H ₂ SO ₄ aqueous solution at current of 1 A / dm ² for 30 minutes /
After energizing at 30 ° C, washing with deionized water c) Electrodeposition coating: voltage 150 V, 2 minutes / 25 ° C, distance between electrodes 150 mm d) Film thickness: using a film thickness meter (Isoscope MP2, manufactured by Helmto Fisher) Measurement e) Smoothness: The appearance of the coating film after coating was visually observed to examine the appearance, unevenness and pinholes. F) Adhesiveness: Put a 1 mm gap (10 x 10) on the coated surface, attach the cellophane tape, and then peel it off and evaluate it by the number of remaining coatings.) Gloss: Glossmeter [digital variable gloss UGV-5D, manufactured by Suga Test Instruments Co., Ltd.] to measure 60-degree specular gloss. H) Weather resistance: Gloss retention rate (%) after 1000 hours of sunshine weatherometer. Li) Pencil hardness: "Mitsubishi Uni Evaluation using the hardness until the coating film is scratched using [Mitsubishi Pencil Co., Ltd. product] Alkali resistance: Observe the state after immersing the coating film in a 5% NaCO ₃ aqueous solution for 24 hours / 20 ° C. Acid resistance: Observe the state of the coating film immersed in a 5% H ₂ SO ₄ aqueous solution for 24 hours at 20 ° C.) Keeping power: Aluminum plate as a cathode, anodized aluminum plate 5
Connect the plate to the anode at 5 cm intervals. The closest anode plate distance to the cathode is 5 cm. Voltage 200V, 2 minutes / 25 ℃

Comparative Example 1 Electrodeposition coating was carried out in the same manner as in Example 1 except that only the electrodeposition coating composition containing the block copolymer obtained in Production Example 1 as a main component was used, and various properties of the coated surface were investigated. It was The results were as shown in Table 1.

Comparative Example 2 Except for using only the electrodeposition coating composition containing the graft copolymer obtained in Production Example 2 as the main component, electrodeposition coating was performed in the same manner as in Example 1 and various properties of the coated surface were investigated. It was The results were as shown in Table 1.

[0033]

[Table 1]

The results, as shown in Table 1, show that the mixing has an excellent effect. That is, the roughness of the coated surface seen in the case of using only the electrodeposition coating composition containing the block copolymer as the main component obtained in Production Example 1 (Comparative Example 1) disappeared, and the graft copolymer was used as the main component. In the case of using only the electrodeposition paint obtained in Production Example 2 (Comparative Example 2), the unsatisfactory throwing power, the delustering effect and the insufficient weather resistance are eliminated, and both components are mixed individually. It has been shown to be effective in overcoming the drawbacks found in some cases.

Production Example 3 The amount of the azo group-containing polydimethylsiloxane compound used was 2
In the same manner as in Production Example 1 except that the amount of decrease was 8 parts and the amount of decrease was 8 parts and the amount was increased with a mixture of methyl methacrylate 40: butyl acrylate 40: methacrylic acid 10: 10-2-hydroxyethyl methacrylate 10. I got electrodeposition paint. Its properties were as follows. Solid content concentration 29.6
%, Polymerization rate 97.8%, viscosity 940 cp (30 ° C.), pH 8.
2, number average molecular weight 28,000 (however, only the above block copolymer), particle size 223 μm.

Production Example 4 Silaplane FM-0725 was reduced to 4 parts, and the reduced portion was changed to 6 parts with methyl methacrylate 30: butyl acrylate 3
An electrodeposition coating composition was obtained in the same manner as in Production Example 2 except that the mixture was mixed in the ratio of 0: 10 methacrylic acid: 10: 2-hydroxyethyl methacrylate to increase the amount. Its properties were as follows. Solid content concentration 30.0%, polymerization rate 99.0%, viscosity
(30 ° C.) 1,400 cp, pH 8.2, particle size 257 μm,
Number average molecular weight 32,000 (however, only the above graft copolymer).

Example 2 An electrodeposition coating composition containing a polysiloxane residue in the main chain obtained in Production Example 3 and a carboxyl group in the side chain as a main component, and an electrodeposition coating obtained in Production Example 2 An electrodeposition coating material containing a polysiloxane residue and a carboxyl group in its side chain was mixed in such a manner that both copolymers had a polymerization ratio of 8: 2, and this was used in the same manner as in Example 1 except that this was used. It was painted.
The results are shown in Table 2.

Comparative Example 3 Electrodeposition coating was performed in the same manner as in Example 2 except that only the electrodeposition coating material obtained in Production Example 3 was used, and the performance of the coated surface was evaluated. The results are shown in Table 2.

Comparative Example 4 Electrodeposition coating was performed in the same manner as in Example 2 except that only Production Example 4 was used, and the performance of the coated surface was evaluated. The results are shown in Table 2.

[0040]

[Table 2]

The results, as shown in Table 2, showed the positive effect of mixing. That is, when the above-mentioned mixed system was used to obtain a semi-glossy coated surface (gloss 30%), it was found that only the electrodeposition paint obtained in Production Example 3 containing a block copolymer as a main component was used (Comparative Example 3). The resulting lack of weather resistance is significantly improved, and the insufficient film thickness is observed when only the electrodeposition coating composition containing the graft copolymer as the main component and obtained in Production Example 4 is used (Comparative Example 4). Insufficient adhesion when wet and insufficient weather resistance are resolved.

[0042]

The resin composition of the present invention is useful as a durable matte electrodeposition coating composition.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C09D 153/00 PGY C09D 153/00 PGY 183/10 PMU 183/10 PMU

Claims (1)

(57) [Claims] 1. A block copolymer containing (A) a polysiloxane residue in its main chain and containing an acid residue in its side chain, and (B) containing a polysiloxane residue and an acid residue in its side chain. A resin composition for electrodeposition coating, comprising both components of the graft copolymer as described above as an aqueous dispersion.