JPH0319872B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-based coating composition for electrodeposition coating which can be dried and cured at room temperature, and more particularly, it relates to a water-based coating composition containing a water-solubilized product or water-dispersed product of maleic acid of a certain specific fatty acid-modified polymer, The present invention relates to an aqueous coating composition for electrodeposition coating that dries at room temperature and contains an organic solvent and water as main components. Electrodeposition coating has many advantages over other coating methods such as flow coating, brush coating, spray coating, and immersion coating, and is used for coating various products including automobiles. ing. For example, compared to the other coating methods mentioned above, the electrodeposition coating method can coat difficult-to-coat parts of objects with complex shapes with a uniform film thickness, and there is less loss of paint, making it more efficient to use. It has the advantages of being extremely high in corrosion resistance, and being less likely to run, sag, or sag on the painted surface. However, on the other hand, most conventional electrodeposition coatings use thermosetting water-based paints, which require baking at a high temperature of 100℃ or higher to harden the coating after electrodeposition. Therefore, it is difficult to apply to coated objects with a large heat capacity, or there are drawbacks such as large economic losses. Therefore, the inventors of the present invention were able to electrodeposit a water-based paint that dries and hardens at room temperature without the need to bake the coating film after electrodeposition, and it is also possible to form a practical coating film at room temperature. Therefore, we thought that it would be possible to eliminate the above disadvantages while taking advantage of the advantages of the electrodeposition coating method, and we investigated a water-based paint composition that dries at room temperature and is suitable for electrodeposition coating. . However, the properties that a water-based coating composition for use in electrodeposition coating should have include that the coating film formed from the coating composition dries and hardens at room temperature; It is required to have the following characteristics. For example, (1)
The paint components are required to have excellent stability without deterioration in the electrodeposition bath; (2) to provide a coating film with excellent smoothness at room temperature; (3) to have good throwing power. Ru. Therefore, the present inventors performed electrodeposition coating using emulsion type and aqueous solution type water-based paints that dry at room temperature, such as alkyd resin-based and maleated polybutadiene-based paints, which are generally used as general-purpose paints. When I tried, among these,
With none of the emulsion type water-based paints, it was not possible to obtain a coating film that was dense and had excellent smoothness, and the throwing power was also insufficient. In addition, water-soluble alkyd resin paints have a limited film hardness and are forced to dry for a long time.
Moreover, since the alkyd resin is easily hydrolyzed in the electrodeposition bath and has poor bath stability, it has defects such as poor throwing power and roughness on the coated surface. On the other hand, water-soluble maleated polybutadiene paints are hardly hydrolyzed but have poor drying properties at room temperature, so they are of little practical use. In this way, the water-based paints that dry at room temperature, which have been conventionally used as general-purpose paints, have excellent electrodeposition bath stability,
It lacks any of the properties required for a water-based paint composition for electrodeposition coating that dries at room temperature, such as coating film throwing power, coating film drying properties, and coating film smoothness. It is difficult to apply it for painting. However, this time, surprisingly, (A) maleic acid and/or anhydride was added to the drying oil fatty acid residue and/or semi-drying oil fatty acid residue bonded to the main chain consisting of the allyl alcohol-containing polymer via an ester bond. Made by adding maleic acid, the glass transition temperature is -30~60℃, the content of the fatty acid residue is 5~70% by weight, and the acid value is 5~5%.
260, aqueous solubilization or dispersion of maleic fatty acid modified polymer, (B) from butyl cellosolve, benzyl alcohol, octyl alcohol, n-butanol, 3-methyl-3-methoxybutanol, 3-methoxybutyl acetate, butyl carbitol, methyl ethyl ketone A water-based paint composition that dries at room temperature and mainly contains one or more selected organic solvents and (C) water can be easily applied by electrodeposition, and has good bath stability and throwing power. , has excellent coating film smoothness,
Furthermore, we discovered that although the drying properties are insufficient when applied using other coating methods, the drying properties at room temperature are surprisingly excellent when applied by electrodeposition. The present invention has now been completed. According to the present invention, the main components are (A) a water-solubilized or water-dispersed product of a maleate of a fatty acid-modified polymer, (B) a specific organic solvent, and (C) water. A room temperature drying type aqueous coating composition for electrodeposition coating is provided. The water-solubilized or water-dispersed product of the above (A) fatty acid-modified polymer maleated product (hereinafter sometimes simply referred to as "modified maleated polymer") used in the present invention is The coating composition of the present invention does not contain any ester bonds and is hardly hydrolyzed in the electrodeposition bath. The coating film is formed to a uniform thickness) and the coating surface has excellent smoothness. Furthermore, since the glass transition temperature of the above-mentioned modified maleated polymer is adjusted to a specific range, the coating film of the coating composition of the present invention after coating is based on the fatty acid of the drying oil or semi-drying oil. It is possible to obtain an initial hardness sufficient for use simply by evaporating volatile substances (water, organic solvents, etc.) from the coating film without using oxidative polymerization. The electrodeposited coating film formed from the coating composition of the present invention is further cured by oxidative polymerization of the fatty acid in the air, improving the flexibility, adhesion, and breaking strength of the coating film. etc. will be further improved. However, when the drying oil or semi-drying oil fatty acid content in the modified maleated polymer increases, contact between the electrodeposition bath and air due to the opening of the electrodeposition bath increases, or turnover becomes longer. In some cases, the fatty acid may undergo oxidative polymerization in the electrodeposition bath and deteriorate the coated surface condition. However, the electrodeposited coating film of the present invention has excellent initial hardness as described above, and furthermore, as described below, the fatty acid is Since the crosslinking reaction can be carried out efficiently, it is possible to minimize the fatty acid content in electrodeposition coating systems where such deterioration may occur, and it is possible to eliminate such defects. Furthermore, the coating film formed from the aqueous coating composition of the present invention has a higher drying property than a coating film formed by applying the aqueous coating composition using other coating methods such as spray coating and dip coating. It has outstanding flexibility, breaking strength, and water resistance. This technological effect is an unexpected and surprising phenomenon. Although the basis for obtaining such technical effects is unknown, it is clear that almost no neutralizing agent is present in the coating film of the aqueous coating composition of the present invention deposited on the anode (object to be coated) using the electrodeposition coating method. The dryness and water resistance of the coating film are improved because it does not contain much of the material, and it is also free from oxygen gas generated at the anode and metal ions (e.g. iron, zinc, lead, calcium ions, etc.) eluted from the anode. Therefore, the crosslinking reaction of the coating film due to oxidative polymerization of fatty acids bonded to the polymer chain (main chain) as pendant side chains is promoted, and as a result, the drying properties, flexibility, breaking strength, and water resistance of the coating film are improved. It is inferred that the performance has significantly improved. As a result, it has become possible to efficiently carry out the crosslinking reaction based on the oxidative polymerization reaction of fatty acids, making it possible to reduce the amount of unsaturated fatty acids used and improving the stability of the electrodeposition bath. It is thought that this contributed to the Further, since the aqueous coating composition of the present invention contains a specific organic solvent, it has become possible to significantly improve the smoothness (gloss) of the coating film surface.
This is thought to be because the organic solvent is distributed into the coating film after electrodeposition and imparts flowability to the coating film. Hereinafter, the water-based coating composition according to the present invention will be explained in more detail. As mentioned above, the aqueous coating composition comprises (A) a water-solubilized or water-dispersed product of a modified maleated polymer;
This is an aqueous coating composition for electrodeposition coating that can be dried and cured at room temperature, containing (B) a specific organic solvent and (C) water as main components. (A) A water-solubilized or water-dispersed product of a modified maleated polymer. Made by adding maleic acid and/or maleic anhydride, the glass transition temperature is -30 to 60°C, the content of the fatty acid residue is 5 to 70% by weight, and the acid value is 5 to 260.
It is a water-solubilized product or a water-dispersed product of a maleated product (modified maleated polymer) of a fatty acid-modified polymer. The modified maleated polymer can be produced by various methods, for example, (a) a polymer using allyl alcohol or allyl alcohol and other polymerizable unsaturated monomers (hereinafter referred to as Ester reaction of drying oil fatty acids and/or semi-drying oil fatty acids (hereinafter sometimes referred to collectively as "unsaturated fatty acids") to copolymers with copolymers with "other vinyl monomers") and then adding maleic acid and/or maleic anhydride (hereinafter, these may be collectively referred to as "maleic acid, etc.") to the unsaturated fatty acid residue in the esterification reaction product, or (b) Addition of maleic acid, etc. to unsaturated fatty acid residues in a polymer made of an esterification reaction product of allyl alcohol and unsaturated fatty acid or a copolymer made of the esterification reaction product and another vinyl monomer It can be obtained by, etc. First, in (a) above, a polymer using allyl alcohol and a copolymer of allyl alcohol and another vinyl monomer can be produced by a method known per se. Here, in a copolymer with other vinyl monomers, it is preferable that allyl alcohol is contained in the copolymer in an amount of 5% by weight or more. Then, unsaturated fatty acids are bonded to the hydroxyl groups contained in the polymer or copolymer through an esterification reaction. In this esterification reaction, the amount of unsaturated fatty acids is
The content of unsaturated fatty acid residues in the modified maleated polymer should be between 5 and 70% by weight, and the esterification reaction should
This is done by heating to ~300°C. Next, maleic acid, etc. is added to the unsaturated fatty acid residues in this esterification reaction product (maleation). You can react with In particular, when there are many hydroxyl groups remaining in the polymer main chain, it is recommended to esterify with a low-molecular or high-molecular acid such as acetic acid, propionic acid, or stearic acid to remove excess hydroxyl groups, and then perform maleation. preferable. When maleating with maleic anhydride,
Requires ring opening of the acid anhydride group attached to the fatty acid residue,
This can be done with water, alcohol, ammonia, amine, etc., and the amount of maleic anhydride is adjusted so that the final acid value is 5-260. When maleating with maleic acid, the amount of maleic acid is adjusted so that the final acid value falls within the above range. Furthermore, in (b) above, the esterification reaction between allyl alcohol and unsaturated fatty acid can be carried out by a method known per se. For example, in the reaction of allyl alcohol and unsaturated fatty acids, both of the above components are mixed in a suitable inert organic solvent, preferably with a boiling point of 180
℃ or less water-immiscible organic solvents, such as aromatic hydrocarbon group-based solvents such as benzene, toluene, and xylene; esterification catalysts such as sulfuric acid; , aluminum sulfate, methyl sulfate, p-
In the presence of toluenesulfonic acid, hydrochloric acid, phosphoric acid, etc. and a polymerization inhibitor such as hydroquinone, methoxyphenol, tert-butylcatechol, benzoquinone, etc., at a temperature of about 110 to 160°C, about 0.5 to 9
This can be carried out by reacting for a period of time. The polymerization reaction of this esterification reaction product or the copolymerization reaction of this esterification reaction product and other vinyl monomers is carried out in accordance with a method known per se for producing an acrylic copolymer, for example, in a solution solution. This can be carried out using a polymerization method, an emulsion polymerization method, a suspension polymerization method, or the like. It is preferable to carry out the polymerization according to a solution polymerization method, in which each monomer component is mixed with a radical polymerization catalyst (for example, an azo-based polymer) in a suitable organic solvent (for example, one or more selected from the organic solvents listed below). compound, peroxide type compound, sulfide, sulfine, diazo compound, nitroso compound, redox type, etc.), usually about 0 to about 180°C, preferably about 40°C.
The reaction can be carried out by continuing the reaction at a temperature of up to about 170°C for about 1 to 20 hours, preferably about 2 to 10 hours. In order to copolymerize the esterification reaction product with another vinyl monomer, the amount of the esterification reaction product blended is such that the content of unsaturated fatty acid residues in the modified maleated polymer is 5 to 70% by weight. For example, it is preferably 5% by weight or more in the copolymer. and,
Addition of maleic acid and/or maleic anhydride to unsaturated fatty acid residues contained in the polymer or copolymer thus obtained (maleation) can be carried out in the same manner as in (a) above. . In (a) and (b) above, other vinyl monomers to be copolymerized with allyl alcohol include, for example, styrene, vinyltoluene, α-methylstyrene,
Acrylonitrile, methacrylonitrile, ester of monohydric alcohol with 1 to 26 carbon atoms and acrylic acid or methacrylic acid, ethylene glycol monoalkyl ether or diethylene glycol monoalkyl ether (alkyl group with 1 carbon number)
~8) and acrylic acid or methacrylic acid, propylene glycol monoalkyl ether or dipropylene glycol monoalkyl ether (alkyl group having 1 to 8 carbon atoms) and acrylic acid or methacrylic acid, other than the above unsaturated fatty acids Examples include addition monomers of a monocarboxylic acid having 4 to 26 carbon atoms and glycidyl methacrylate or glycidyl acrylate.
It is desirable to use a monomer that has excellent copolymerizability with the allyl alcohol or the esterification product of allyl alcohol and an unsaturated fatty acid, and the resulting modified maleated polymer is stable at high temperatures. Other butadiene, isoprene, chloroprene, pentadiene, vinyl acetate, vinyl chloride, beoba monomer (manufactured by Siel Chemical Co., USA,
Monomers used in general radical polymerization such as (trade name) can also be used as other monomers. Unsaturated fatty acids are components that impart drying properties at room temperature, such as safflower oil fatty acids, soybean oil fatty acids, linseed oil fatty acids, sesame oil fatty acids, eno oil fatty acids, grape kernel fatty acids, corn oil fatty acids, hempseed oil fatty acids, and poppy oil fatty acids. fatty acids, sunflower oil fatty acids,
Those containing many non-conjugated double bonds and having carbon numbers of 6 to 30, preferably 17 to 20, such as tall oil fatty acids, cottonseed oil fatty acids, rubber seed oil fatty acids, and walnut oil fatty acids, can cause the maleation reaction to gel. Preferred are safflower oil fatty acids, linseed oil fatty acids, soybean oil fatty acids, tall oil fatty acids, and mustard oil fatty acids.
Oiticica oil fatty acids, peanut oil fatty acids, tung oil fatty acids, dehydrated castor oil fatty acids, hydene fatty acids, etc. can also be used. In addition, the modified maleated polymer obtained as described above can be made water-soluble or water-dispersed by neutralizing some or all of the carboxyl groups formed by maleic acid, etc. in the polymer with an aqueous solution of a neutralizing agent. This is done by Examples of neutralizing agents that can be used include ammonia, amines, alkali metal hydroxides, and alkali metal carbonates or bicarbonates. The amines that can be used include primary, secondary or tertiary lower alkyl amines; primary, secondary or tertiary lower alkanolamines; and cycloalkylamines. In addition, examples of alkali metal hydroxides include potassium hydroxide,
Sodium hydroxide, etc.; as the alkali metal carbonate or bicarbonate, sodium carbonate, sodium bicarbonate, etc. can be used. Among these neutralizing agents, triethylamine is particularly preferred. The amount of the neutralizing agent used can generally be 0.1 to 2.0 equivalents, preferably 0.5 to 1.2 equivalents, relative to the carboxyl groups in the modified maleated polymer. The modified maleated polymer used in the present invention has (1) a glass transition temperature of -30°C to 60°C, preferably -25°C to 50°C, more preferably -23 to 20°C; (2) a drying oil; The content of fatty acid residues and/or semi-drying oil fatty acid residues is 5 to 70% by weight, preferably 10 to 70% by weight.
60% by weight, more preferably 20 to 55% by weight; and (3) it is important to adjust the acid value to 5 to 260, preferably 10 to 150, more preferably 20 to 100; Those skilled in the art can easily determine the proportions of each monomer to produce a maleated fatty acid-modified addition polymer that satisfies these property requirements by conducting simple small-scale experiments. Regarding the properties of this modified maleated polymer, when the glass transition temperature is lower than -30℃, the initial coating film curing immediately after electrodeposition coating using the copolymer is insufficient; If this happens, the flexibility, adhesion, impact resistance, etc. of the sufficiently oxidized and dried coating film will deteriorate. In addition, if the content of unsaturated fatty acids is less than 5% by weight, the oxidative drying properties of the coating film cannot be expected, resulting in insufficient hardness, while if it exceeds 70% by weight, oxidative polymerization progresses in the electrodeposition coating bath. However, it is not possible to obtain a uniform painted surface. Furthermore, if the acid value is lower than 5, it becomes difficult to water-solubilize or water-disperse the fatty acid-modified copolymer, while if it is higher than 260, the water resistance of the coating film decreases, both of which are unfavorable, and the purpose of the present invention is to cannot be achieved. The glass transition temperature of the modified maleated polymer in the present invention was measured using a torsional plate analyzer (manufactured by Rigaku Corporation, TBA-8120A1) based on the principle of the free torsional vibration method. The temperature at which the mechanical damping index of the fiber impregnated with the fatty acid-modified carboxyl group-containing copolymer reaches its peak was measured. Impregnation of the polymer into the fibers is carried out using a solution of the polymer (solids content
40% by weight ethyl acetate/butyl cellosolve = 1/
The braided cord specified by the measuring device was immersed in the solution (1 solution), then taken out and dried under vacuum to remove the solvent. In addition, unsaturated fatty acids may deteriorate the stability of the electrodeposition bath, so it is preferable to keep the amount as small as possible. may be contained in a large amount in the modified copolymer. (B) Organic solvent The organic solvent used in the present invention is butyl cellosolve,
Penzyl alcohol, octyl alcohol, n-
butanol, 3 methyl 3 methoxybutanol, 3
- One or more selected from methoxybutyl acetate and butyl carbitol,
These organic solvents are appropriately distributed in the electrodeposited coating film, impart fluidity to the coating film, and can significantly improve smoothness. The blending amount of the organic solvent is 15 to 500 parts by weight, further 30 to 200 parts by weight, per 100 parts by weight of the modified maleated polymer (A).
Particularly preferred is 50 to 150 parts by weight. In the coating composition of the present invention, if organic solvents other than those specified above are blended, the smoothness of the coating film cannot be improved, but depending on the purpose of application, the above specified organic solvents and other organic solvents may be used in combination. It is also possible to do so. Examples of solvents other than the above include toluene,
Examples include xylene, methyl ethyl ketone, and methyl isobutyl ketone. (C) Water Tap water, tap water, deionized water, etc. can be used. The coating composition of the present invention comprises a modified maleated polymer made water-soluble or water-dispersed in this way,
It contains an organic solvent and water as its main components, and can be used as is for electrodeposition coating, but if necessary, as is usually done,
Coloring pigments, extender pigments, antirust pigments, surfactants, etc. may also be blended. Furthermore, it is possible to add commonly used metal salt desiccants such as cobalt naphthenate and lead naphthenate in order to improve the dry curing properties of the coating film at room temperature; It is preferable to select the amount added depending on the required degree of bath stability. Specifically, modified maleated polymer 100
It is preferable to add the metal salt desiccant in an amount of 0.001 to 0.1 part by weight based on the amount of metal per part by weight. The aqueous coating composition of the present invention produced as described above can be widely used as a coating for electrodeposition coating. In electrodeposition coating, the content of the modified maleated polymer in the aqueous coating composition in the electrodeposition coating bath is generally 3 to 25% by weight, preferably 5 to 20% by weight.
% by weight. The object to be coated may be of any size and shape, as long as at least its surface is made of conductive metal. In particular, since the resin composition of the present invention does not require the coating film to be cured by heating, it can be advantageously applied to objects having a large heat capacity and for which it is difficult to cure the coating film by heating. . Specifically, examples thereof include iron, aluminum, steel, and those whose surfaces have been subjected to chemical conversion treatment (for example, zinc phosphate treatment, iron phosphate treatment, etc.). The electrodeposition coating operation can be carried out in a manner known per se. For example, the temperature of the electrodeposition coating bath prepared as described above is set at 10 to 50°C, preferably 20 to 35°C.
The object to be coated is immersed in this as an anode, and the voltage between it and another cathode is 10 to 300 volts, preferably 30 to 250 volts, for 30 seconds to 20 minutes, preferably 1 to 10 volts. A coating film can be deposited on the surface of the object to be coated (anode) by applying electricity for a minute. Thereafter, if the object to be coated is taken out of the electrodeposition bath and left at room temperature, the coating film dries and hardens. Of course, if necessary, the object to be coated may be cured by heating to an extent (approximately 250° C. or less) that the coating film components will not be thermally decomposed. Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, in the above, "part" and "%" refer to parts by weight and weight %, respectively.
It is. Example 1 (a) Production of modified maleated polymer: RJ-100 (number average molecular weight 1600, OH content 7.8%
1264 parts of styrene-allylic alcohol copolymer (manufactured by Monsanto Chemical Co., Ltd.), linseed oil fatty acid
A mixture of 1,180 parts of xylene, 100 parts of xylene, and 1.5 parts of dibutyltin oxide was placed in a reactor, and the mixture was heated at 230°C while removing the condensation water produced from the reaction system.
React for 10 hours to obtain a resin with an acid value of 5.5. To this was added 145 parts of maleic anhydride, and a maleation reaction was carried out at 190-200°C for 7 hours. After removing xylene and unreacted maleic acid by vacuum distillation, water was added to open the anhydride groups, and n-butyl cellosolve was added to obtain modified maleated polymer A with a total acid value of 56 and solid content of 80%. Obtained. (b) Manufacture of water-based coating composition: Add n-butyl cellosolve to the modified maleated polymer A obtained in (a) above in an amount of 30 parts per 100 parts of resin solid content, and further add octanol to the resin solid content. Added at a rate of 30 parts per 100 parts per minute. Then, the total acid value of the modified maleated polymer is approximately
Neutralized using 0.9 equivalents of triethylamine. Next, the resin solid content is added to this neutralized resin solution.
Pigment Titanium Dioxide JR-600 (trade name, manufactured by Teikoku Kako Co., Ltd., rutile type titanium white) 29 per 100 parts
0.4 parts of Carbon Black MA-100 (product name: Carbon Black, manufactured by Mitsubishi Kasei Corporation) and 1.0 parts of strontium chromate (manufactured by Kikuchi Color Industries, Ltd.), dispersed with a paint conditioner, and then mixed with the resin. The total content of minute and pigment minutes is 10
% with ion-exchanged water to obtain a water-based paint composition for electrodeposition coating. (c) Electrodeposition coating: The electrodeposition coating composition was placed in a 4L hard polyvinyl chloride container that can be stirred with a magnetic stirrer, and a 75 x 50 x 0.8 (mm) degreased and cleaned polished mild steel plate was used as an electrode. SPCCJIS-G3141 was used as an anode and a cathode. Connect a DC voltage rectifier between both electrodes (Takasago Manufacturing Co., Ltd. TYPE G-25M GP0250-
5) for 2 minutes. The distance between the electrodes was 15 cm, and both electrodes were each immersed in the bath composition to a depth of 10 cm. After electrodeposition at 150 volts for 2 minutes, the mild steel plate on the anode side was removed from the bath and hung vertically to dry at room temperature. The stability of the electrodeposition coating composition in the electrodeposition bath and the performance test results of the resulting coating film are summarized in Table 1 below. Example 2 (a) Production of modified maleated polymer: RJ-100 (number average molecular weight 1600, OH content 7.8%
1264 parts of styrene-allylic alcohol copolymer (manufactured by Monsanto Chemical Co., Ltd.), soybean oil fatty acid
A mixture consisting of 1,180 parts of xylene, 100 parts of xylene, and 1.5 parts of dibutyltin oxide was placed in a reaction vessel, and the mixture was heated at 230°C while removing the condensed water produced from the reaction system.
React for 10 hours to obtain a resin with an acid value of 5.5. Add 116 parts of maleic anhydride to this and heat at 190°C to 200°C.
Carry out the maleation reaction for a period of time. After removing xylene and unreacted maleic acid by distillation under reduced pressure, the mixture was ring-opened with water and n-butyl cellosolve was added to obtain a modified maleated polymer B having a total acid value of 45 and a solid content of 79.5%. (b) Production and electrodeposition coating of aqueous coating composition Into the modified maleated polymer B solution obtained in (a) above,
After adding n-butyl cellosolve to 30 parts per 100 parts of the resin solid content and further adding benzyl alcohol at a ratio of 50 parts per 100 parts of the resin solid content, approximately Neutralized using 0.9 equivalents of triethylamine. Then, a pigment was dispersed in this neutralized resin solution in the same manner as in Example 1 (1)-b to obtain a resin composition for electrodeposition coating, and electrodeposition was applied in the same manner as in (1)-c. and used it for testing. The results are shown in Table 1 below. Example 3 (a) Production of modified maleated polymer: RJ-100 (number average molecular weight 1600, OH content 7.8%
1264 parts of styrene-allylic alcohol copolymer (manufactured by Monsanto Chemical Co., Ltd.), linseed oil fatty acid
A mixture consisting of 1,180 parts of xylene, 100 parts of xylene, and 1.5 parts of dibutyltin oxide was placed in a reaction vessel, and the mixture was heated at 230°C while removing the condensed water produced from the reaction system.
React for 10 hours to obtain a resin with an acid value of 5.5. To this was added 87 parts of maleic anhydride, and a maleation reaction was carried out at 190°C to 200°C for 7 hours. After removing xylene and unreacted maleic acid by vacuum distillation, the ring was opened with water and n-butyl cellosolve was added to obtain a modified maleated polymer C having a total acid value of 45 and a solid content of 80%. (b) Production and electrodeposition coating of aqueous coating composition Into the modified maleated polymer C solution obtained in (a) above,
After adding n-butyl cellosolve to 35 parts per 100 parts of solid content of the polymer and adding benzyl alcohol at a ratio of 35 parts per 100 parts of solid content of the polymer, the total acid value of the polymer was determined. for about
Neutralized using 0.9 equivalents of triethylamine. Then, a pigment was dispersed in this neutralized solution in the same manner as in Example 2 (b) to obtain a coating composition for electrodeposition, and electrodeposition was performed in the same manner as in Example 2 (c). Tested. The results are shown in Table 1 below. Comparative Example 1 A mixture of the following components: neopentyl glycol 52.5 parts trimethylolpropane 68.25 parts isophthalic acid 149.4 parts trimellitic acid 13.44 parts linseed oil fatty acid 70 parts para-tert-butylbenzoic acid 26.7 parts was subjected to a condensation reaction at 240°C for 7 hours. 30 parts of n-butyl cellosolve and 30 parts of benzyl alcohol were added to a drying oil fatty acid-modified alkyd resin with an acid value of 40, a Gardner viscosity of V to W, and a fatty acid content of 20%, and then the total acid value of the resin was It was neutralized using about 1.0 equivalent of triethylamine. Then, pigment per 100 parts of solid content of the alkyd resin.
Titanium Dioxide JR-600, 30 parts, Carbon Black MA-100, 0.4 parts, Strontium Chromate, 1.0 parts were blended and dispersed with a paint conditioner, resulting in a total resin and pigment content of 10%. The mixture was diluted with ion-exchanged water to obtain a water-based coating composition for electrodeposition coating. Electrodeposition coating was performed in the same manner as in Example 1, and the sample was subjected to a test as a comparative example. The results are summarized in Table 1 below. Comparative Example 2 The composition obtained up to the dispersion of the pigment in Example 1 was diluted with water and adjusted to a viscosity of 25 seconds for food cup No. 4, and a degreased and cleaned polished mild steel plate of 75 x 50 x 0.8 (mm) was prepared. A test board was prepared by spray painting SPCCJIS-G3141. A test plate with a film thickness of 20 μm in a dry state was used for the test. The results are shown in Table 1 below.

【table】

【table】

Claims (1)

[Scope of Claims] 1 (A) Maleic acid and/or maleic anhydride in the drying oil fatty acid residue and/or semi-drying oil fatty acid residue bonded to the main chain consisting of an allyl alcohol-containing polymer via an ester bond. The glass transition temperature is -30 to 60℃,
Water soluble or water dispersion of maleic acid of fatty acid modified polymer having fatty acid residue content of 5 to 70% by weight and acid value of 5 to 260 (B) Butyl cellosolve, benzyl alcohol, octyl alcohol, n-butanol , 3-methyl-3-methoxybutanol, 3-methoxybutyl acetate, butyl carbitol, methyl ethyl ketone, and one or more organic solvents selected from methyl ethyl ketone; thing.