JPH11349866A - Lusterless electrodeposition coating material and electrodeposition coating method therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lusterless electrodeposition coating material which exhibits good electrophoretic properties, is excellent in homogeneous dispersibility in a bath, and is excellent in homogeneous design properties and to provide an electrodeposition coating method using the same. SOLUTION: This coating material contains a resin compsn. which is prepd. by neutralizing a mixture comprising, based on the solid content, (A) 100 pts.wt. acrylic resin having an acid value of 30-100, a hydroxy value of 60-150, and a wt. average mol.wt. of 20,000-100,000, (B) 50-100 pts.wt. alkyl-etherified methylolmelamine resin of which at least 40% of all the ether groups are 4-10C alkyl ether groups and the rest are 3C or lower alkyl ether groups, and (C) 1-10 pts.wt. epoxy compd. having at least two epoxy groups per molecule and an epoxy equivalent of 500 or lower with a base to give an aq. resin dispersion and subjecting this dispersion to microgelation reaction at 40-120 deg.C. The electrodeposition coating method uses the coating material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a matte electrodeposition paint and a matte electrodeposition coating method. Specifically, (A)
An acrylic resin, (B) an alkyl etherified methylol melamine resin in which the amount of alkyl ether groups having 4 to 10 carbon atoms is 40% or more of the total ether groups and the remainder is an alkyl ether group having 3 or less carbon atoms, and (C) an epoxy compound A matte electrodeposition paint containing fine electrodepositable microgel particles in water, and using the electrodeposition paint to obtain a coating film by an electrodeposition coating method using an object to be coated as an anode. And a matte electrodeposition coating method characterized by the following.

[0002]

2. Description of the Related Art Heretofore, as a matte paint which does not obscure the hue and fine pattern of the object to be coated itself, one in which micro silica is dispersed in the paint has been generally used.
However, microsilica is inferior in chemical resistance, especially in alkali resistance, and a coating film having good transparency cannot be obtained. There are drawbacks such as a difference in gloss, particularly on the upper and lower surfaces, depending on the part to be coated.

On the other hand, there is known a method of dispersing organic fine particles having a small specific gravity in a coating material. However, this method, for example, a method in which organic fine particles are dispersed in a paint as described in JP-B-51-8975 has practical utility as a general solvent type spray paint or a dip type paint. However, it was unsuitable as an electrodeposition paint. The reason for this is that since the electrophoretic properties of the organic fine particles are not considered at all, the organic fine particles do not have the characteristic of electrophoresis at a constant rate when energized, and sometimes fall off by washing with water.

In the electrodeposition paints and coatings, the viscosity of the electrodeposition bath is set to be substantially the same as the viscosity of water from the viewpoint of diffusion of generated Joule heat and washing properties. The body has such a low viscosity (usually a water content of 80-9
5%) in an electrolyte bath, the uniform dispersibility is poor, and in the electrodeposition coating, a solvent used for the purpose of adjusting gloss, improving washability, lowering the coating film resistance, and other components other than the essential components of the coating are used. There were drawbacks such as the elimination of contaminating electrolytes was not considered.

[0005]

On the other hand, there is known a method of forming an insoluble intra-particle microgel in a resin for electrodeposition paint to achieve low gloss. Various methods for forming microgels have been proposed, one of which is to introduce an alkoxysilyl group into the base resin and form a insoluble intraparticle microgel in the copolymer resin by a condensation reaction with the alkoxysilyl group. Has been proposed. For example, JP-A-59-67396, JP-A-64-14281, and JP-A-05-263296 correspond to this technique, but the gloss value varies depending on the coating conditions, and the cleaning process after electrodeposition. In particular, there are constraints on the electrodeposition coating workability, such as being susceptible to the effects of

There is also a method in which an epoxy compound is reacted with a base resin obtained by copolymerizing an α, β-ethylenically unsaturated carboxylic acid monomer. For example, JP-A-59-13827 and JP-A-60-163979 correspond to this technology. However, these techniques use Nikarac MX-40 (70% methyl ether group, 30% butyl ether group) manufactured by Sanwa Chemical Co., Ltd. as a melamine resin, as shown in Examples, and use acrylic resin / melamine resin. The ratio is 100/37 to 100/46 by weight (Japanese Unexamined Patent Publication (Kokai) No. 59-13827).
/ 44, and JP-A-60-163979, in Examples 1, 2, and 3, 100/45, 100/37,
100/46) and the melamine resin is 50
% Or less of the amount of the melamine resin.

Therefore, these techniques can provide a stable matting effect as compared with the above-mentioned matting technique using an alkoxysilyl group, but the coating film is rough and smooth due to insufficient flow during baking. There is a problem in that it has a poor feeling and a feeling of durability, and also has a poor concealing property of a die mark peculiar to an aluminum molding material, which is a major problem in that the commercial value of the coating material is reduced. Insufficient flow at the time of baking generates pinholes in the coating film, which causes a problem in chemical resistance such as acid resistance and alkali resistance.

[0008] These factors are attributable in part to the use of a hydrophilic melamine resin having 70% methyl ether groups in the melamine resin. Hydrophilic melamine resin is well compatible with acrylic resin, so it hardly separates on the coating surface during the baking process, so the flowability during baking is insufficient, and the coating film formed during electrodeposition coating Since the surface irregularities remain almost intact after baking without disappearing, the coating film surface is rough,
A coating film with a poor smoothness and lack of feeling is obtained. Also, with respect to dice marks, which are fine grooves on the surface of the material, the flowability at the time of baking is insufficient, so that the coating film cannot sufficiently fill the grooves during the baking process, resulting in a decrease in dice mark hiding ability.

As another factor, if the amount of melamine resin used is less than 50% by weight with respect to the acrylic resin 100, most of the melamine resin is used for a crosslinking reaction with the acrylic resin, and during the baking process, Almost no melamine resin separated on the surface of the coating film remains, so that the flowability at the time of baking is insufficient and the above-mentioned problem occurs.

In view of the above, the present inventors have made intensive studies to solve the above-mentioned problems in a method for forming a microgel from the reaction between a carboxyl group and an epoxy group. By combining resins and further restricting the use ratio of acrylic resin and epoxy compound, the flowability during baking is large, the surface roughness of the coating film is small, the gloss is excellent in smoothness, feeling of holding, and dice mark concealment It has been found that an erased coating film can be obtained.

[0011]

That is, the present invention provides:
(A) an acrylic resin having an acid value of 30 to 100, a hydroxyl value of 60 to 150, and a weight average molecular weight of 20,000 to 100,000;
(B) an alkyl etherified methylol melamine resin in which the content of alkyl ether groups having 4 to 10 carbon atoms is 40% or more of the total ether groups, and the remainder is an alkyl ether group having 3 or less carbon atoms; and (C) two per molecule. 3 of an epoxy compound having the above epoxy group and having an epoxy equivalent of 500 or less.
(A) 10
The mixture in which (B) is 50 to 100 and (C) is 1 to 10 is neutralized with a base to obtain an aqueous resin dispersion, and then the aqueous resin dispersion is microgeled at 40 to 120 ° C. The present invention relates to a matte electrodeposition paint and a method of electrodeposition coating the same, which contain a resin composition obtained by a chemical reaction.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The acrylic resin (A) used in the present invention has an acid value of 30 to 100, preferably 40 to 80, and a hydroxyl value of 6.
0-150, preferably 70-130,
(A1) α, β-ethylenically unsaturated carboxylic acid monomer, (a2) hydroxy group-containing α, β-ethylenically unsaturated monomer, and (a3) other α, β-ethylenically unsaturated monomer It can be produced by copolymerizing monomers.

The above component (a1) is used for imparting water dispersibility and electrophoresis to the copolymer resin and for forming a microgel by reacting with the epoxy compound (C). , Methacrylic acid, crotonic acid, vinyl acetic acid, itaconic acid, maleic acid, maleic anhydride,
Fumaric acid, citraconic acid and the like. These may be used alone or in combination of two or more.

The amount of component (a1) used is such that the acid value of the acrylic resin (A) is from 30 to 100, preferably from 40 to 80. If the acid value of the acrylic resin (A) is less than 30, sufficient water dispersion stability cannot be obtained, and the reaction with the epoxy compound (C) is insufficient, so that a sufficient matting effect cannot be obtained. On the other hand, if it exceeds 100, the electrophoretic properties are poor, and the water resistance and weather resistance are reduced.

The component (a2) imparts curability by reacting with an alkyl etherified methylol melamine resin during baking of a coating film. For example, 2-
Hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate and the like, and modified lactones thereof; These can be used in combination.

The component (a2) is used in such a range that the hydroxyl value in the copolymer resin is 60 to 150, preferably 70 to 130. If the hydroxyl value is less than 60,
When the curing property is insufficient, and when it exceeds 160, the coating film becomes brittle and the water resistance is reduced, so that sufficient performance cannot be obtained.

Further, as the component (a3) which forms the skeleton of the copolymer resin, an alkyl ester of acrylic acid or methacrylic acid or other vinyl monomers can be used. Specific compounds include, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl Methacrylate, t-butyl acrylate, t-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, heptyl acrylate, heptyl methacrylate, diethylene glycol monoacrylate Over DOO, acrylic acid and diethylene glycol monomethacrylate, esters of methacrylic acid, styrene, alpha-methyl styrene,
Vinyl monomers such as vinyltoluene, vinyl acetate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, methylolacrylamide, methylolmethacrylamide, methoxymethylacrylamide,
Amide monomers such as n-butoxymethylacrylamide, diacetone acrylamide, diacetone meacrylamide and the like can be mentioned. These can be used alone or in combination of two or more.

The preferred weight average molecular weight of the acrylic resin (A) is 20,000 to 100,000. When the weight average molecular weight is 20,000 or less, the coating film durability cannot be sufficiently obtained, and when it is 100,000 or more, the water dispersibility decreases, and the handling property of the paint becomes poor. In particular, in terms of matting properties and paint stability, the weight average molecular weight is 2500.
It is preferably from 0 to 70000. The molecular weight is measured using a GPC measuring device and a polystyrene standard sample. Further, the glass transition temperature of the acrylic resin (A) is preferably from -10 to 60C, and particularly preferably from 10 to 40C from the viewpoint of mattability and flexibility.

The acrylic resin (A) described above can be obtained by subjecting the monomers (a1), (a2) and (a3) to solution polymerization, non-aqueous dispersion polymerization, bulk polymerization, emulsion polymerization, suspension polymerization and the like. Although it can be obtained by polymerization by a known method, solution polymerization is particularly preferred, and the reaction temperature is usually 4
0-170 ° C is chosen.

As the reaction solvent, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol,
Isobutyl alcohol, sec-butyl alcohol, t
-It is preferable to use a hydrophilic solvent such as butyl alcohol, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol monobutyl ether. Known polymerization initiators such as organic peroxides, azo compounds, ammonium persulfate, and potassium persulfate can be used as the polymerization initiator.

In order to disperse the obtained acrylic resin (A) in water, at least a part of the carboxyl groups in the resin is neutralized with a basic substance, for example, an organic amine or an inorganic base. Such basic substances include monomethylamine,
Dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, monobutylamine, dibutylamine, alkylamines such as tributylamine, diethanolamine, diisopropanolamine, triethanolamine, dimethylethanolamine, Examples thereof include alkanolamines such as diethylethanolamine, alkylenepolyamines such as ethylenediamine, propylenediamine, diethylenetriamine, and triethylenetetramine, ammonia, ethyleneimine, pyrrolidine, piperidine, piperazine, morpholine, sodium hydroxide, and potassium hydroxide.
The neutralization ratio with such a basic substance is suitably from 30 to 100%, and particularly preferably from 50 to 90%, since water dispersibility is good and gloss unevenness does not occur.

The alkyl etherified methylol melamine resin (B) used in the present invention has an alkyl ether group having 4 to 10 carbon atoms in an amount of 40% or more of the total ether groups, and the remainder is an alkyl ether group having 3 or less carbon atoms. Alkyl-etherified methylol melamine resin, basically, after all hydrogen bonded to amino group present in one molecule of melamine is converted to methylol, then, when the methylol group is alkyl-etherified with alcohol, 40% or more thereof Has 4 carbon atoms
The remaining methylol groups are alkyl etherified methylol melamine resins etherified with 10 to 10 alcohols and the remaining methylol groups are alkyl etherified with methyl alcohol, ethyl alcohol, or propyl alcohol. Carbon number 4
A butyl ether group is preferred for the alkyl ether groups of 10 to 10, and a methyl ether group is preferred for the remaining alkyl ether groups. The condition that the alkyl ether group having 4 to 10 carbon atoms is 40% or more has no problem even when one kind of melamine resin is used or two or more kinds of melamine resins are combined.

When the content of the hydrophobic alkyl ether group having 4 to 10 carbon atoms is less than 40%, the melamine resin (B) becomes too hydrophilic, and the compatibility with the acrylic resin (A) is too good. During the process, (B) the melamine resin hardly separates on the surface of the coating film, so that the flow property at the time of baking is insufficient, and the coating film surface is rough, smooth,
A coating film with a poor feeling of holding is obtained. Also, the dice mark concealing property is reduced.

An alkyl ether group having 4 to 10 carbon atoms is
The melamine resin (B) of the present invention having 0% or more is appropriately phase-separated into the surface layer of the coating film during the baking process, and improves the flowability of the coating film and contributes to the smoothness and low glossiness of the coating film. It is thought that it is. Further, the content of the alkyl ether group having 4 to 10 carbon atoms is more preferably 50% or more, and 50 to 80% is more preferable in consideration of the water washability, the unevenness of the gloss of the coating film, and the opalescence.

The amount of the melamine resin (B) used in the present invention is as follows:
(A) 50 to 100 of acrylic resin 100 by weight
However, if it is less than this range, there is almost no (B) melamine resin separated on the surface of the coating film during the baking process, sufficient flowability cannot be ensured, and the coating film surface is rough, smooth, and sticky. A coating film with poor feeling is obtained. Also, the dice mark concealing property is reduced. In addition, because of insufficient cross-linking of the coating film, mechanical properties, solvent resistance, chemical resistance and the like are reduced. On the other hand, if the amount is large, the affinity with the acrylic resin (A) becomes insufficient, and the melamine resin (B) partially separates from the acrylic resin (A) in the aqueous dispersion, resulting in poor stability of the aqueous dispersion and dispersion particles. Problems such as non-uniformity of the diameter, poor water washability after electrodeposition, water repellency, unevenness of the gloss of the coating film, and milkiness are caused.

The index of the flowability of the coating film is evaluated by the gloss of the coating film during the baking process. Specifically, the gloss of the electrodeposited coating film is measured after air-drying and then left at 70 ° C. for 20 minutes. This gloss is referred to as 70 ° C. gloss. The higher the 70 ° C. gloss, the greater the flow property during baking, the less rough the coating is, and the more excellent the coating is in smoothness, solid feeling, and dice mark hiding. Can be In order to secure the flow property at the time of baking, it is preferable to secure the gloss at 70 ° C. of 25 or more.

The epoxy compound (C) used in the present invention is an epoxy compound having an epoxy equivalent of 500 or less and having two or more epoxy groups per molecule. Is a glycidyl ether of polyphenol having two phenolic hydroxyl groups, and preferred polyphenols are resorcin, hydroquinone, 2,2-bis- (4-hydroxyphenyl) -propane (commonly known as bisphenol A), and 4,4 ′. −
Examples thereof include dihydroxybenzophenone, 1,1-bis- (4-hydroxyphenyl) -methane, 1,1-bis- (4-hydroxyphenyl) -ethane, and 4,4′-dihydroxybiphenyl. Another one is 1
Glycidyl ether of a polyol having two or more alcoholic hydroxyl groups in the molecule, and preferred polyols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol,
Examples thereof include low-molecular-weight polyols such as dipropylene glycol, 1,4-cyclohexanediol, trimethylolpropane, glycerin, and pentaerythritol, and oligomer diols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Another example is a glycidyl ester of a dicarboxylic acid having two or more carboxyl groups in one molecule. Preferred dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, hexahydrophthalic acid, adipic acid and the like. Can be mentioned. Further, as an alicyclic epoxy compound, an epoxy compound having a cyclohexene oxide group (Celloxide-2021 manufactured by Daicel Corporation,
CELOXIDE-2080 etc.), other EH manufactured by Daicel
PE-3150 can be mentioned. Further, glycidyl acrylate, glycidyl methacrylate, copolymers of epoxy group-containing vinyl monomers such as allyl glycidyl ether and other vinyl monomers can be exemplified, but are not limited thereto, the epoxy compound Is also possible.

The epoxy compound (C) of the present invention is used in an amount of 1 to 10 by weight based on 100 parts of the acrylic resin (A).
However, if it is less than this range, the amount of microgel formed is small, and the gloss reduction effect is insufficient. Conversely, when the amount is large, the coating film does not flow sufficiently during the baking process even if the melamine resin (B) of the present invention is used in a predetermined amount, which is not preferable. This is probably because the amount of microgel produced was too large and flowability was suppressed. A more preferable range of the epoxy compound (C) is (A) an acrylic resin 1 by weight ratio.
00 to 3 to 6.

With respect to the microgel formation reaction, (A) an acrylic resin, (B) a melamine resin and (C) an epoxy compound are mixed and dispersed in water.
C., preferably at 60-100.degree. When the temperature is lower than 40 ° C., the microgelation reaction hardly proceeds, and a sufficient matting effect cannot be obtained. On the other hand, when the temperature is higher than 120 ° C., the microgelation reaction proceeds too much, and the flowability at the time of baking of the coating material is reduced, and a large number of pinholes are formed in the coating film to lower the chemical resistance. Further, the surface roughness of the coating film is remarkable, which is not preferable.

The reaction can be carried out without using a catalyst, but it is also possible to use an acid catalyst in combination. For example, formic acid, acetic acid, oxalic acid, sulfonic acid, hydrochloric acid, sulfuric acid, nitric acid,
There are phosphoric acid and the like, and sulfonic acid is particularly preferable. As the sulfonic acid, methanesulfonic acid, ethanesulfonic acid, toluenesulfonic acid, isopropylbenzenesulfonic acid,
Examples thereof include nonylbenzenesulfonic acid, decylbenzenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonyldinaphthalenesulfonic acid, dihexyldinaphthalenesulfonic acid, and didecyldinaphthalenesulfonic acid.

Depending on the required performance, workability, cost and the like, if necessary, for example, xylene resin, polyester resin, urethane resin, etc. can be used in combination.
In this case, it is used in the same manner as the melamine resin.

The electrodeposition paint obtained according to the present invention is diluted with deionized water or deionized water partially containing a hydrophilic solvent, if necessary, and then subjected to electrodeposition coating. When the matte electrodeposition coating composition of the present invention is applied, the solid content concentration of the coating bath is suitably from 4 to 20% by weight. If it is lower than 4% by weight, it takes a long time to obtain a required coating film thickness, and 2
If it exceeds 0% by weight, the state of the bath liquid becomes unstable, and the amount of paint taken out of the coating system is also a problem.

With respect to the coating method, electrodeposition coating is performed using the object to be coated as an anode. The coating voltage is 30 to 350 V, preferably 50 to 300 V, and the energization time is 0.5 to 7 V.
Minutes, preferably 1 to 5 minutes. The higher the voltage, the shorter the energization time, and conversely, the lower the voltage, the longer the energization time. The coating voltage may be applied by applying the set voltage at the same time as energization or by gradually increasing the set voltage to the set voltage. The coated object is washed with water if necessary, and then heated at 150 to 200 ° C. for 15 to 60 minutes to obtain a final coating film. The coating thickness is preferably from 5 to 30 μm.

The object to which the electrodeposition coating method of the present invention is applied is not particularly limited as long as it has conductivity, but when aluminum or an aluminum alloy is used, it is excellent in performance such as smoothness. In addition, a uniform matte coating is obtained, and mechanical properties, solvent resistance, chemical resistance, weather resistance,
A coating film excellent in workability and the like can be obtained. For electrodeposition coating, an object to be coated is used as an anode, an electrodeposited deposition film is obtained by applying a predetermined voltage, and if necessary, washed by a conventional method, and then, through a baking process, low gloss, mechanical properties,
A coating film excellent in solvent resistance, chemical resistance, weather resistance, workability and the like can be obtained.

[0035]

The present invention will be described below with reference to examples. Parts are parts by weight unless otherwise indicated.

Synthesis of Acrylic Resin [Synthesis Examples 1 to 3] (Synthesis of Resin Solutions A-1 to 3) A reaction apparatus having a stirrer, a thermometer, a monomer dropping device, and a reflux cooling device is prepared.

[0037]

[Table 1]

According to the formulations of Synthesis Examples 1 to 3 shown in Table 1,
(1) and (2) were charged into a reactor, the temperature was raised to the reflux temperature with stirring, (3) to (9) were previously mixed uniformly, and then added dropwise over 3 hours. The temperature was maintained at 90 ° C.
1.5 hours after the completion of dropping, (10) was added, and 9
The reaction was continued at 0 ° C. for 1.5 hours to obtain transparent and viscous resin liquids A-1 to A-3 having a resin solid content of 65%. Table 1 shows the characteristic values of the obtained resin liquids A-1 to A-3.

[0039]

[Table 2]

Epoxy compound: Sumiepoxy ELA-128P (bifunctional, epoxy equivalent 186) manufactured by Sumitomo Chemical Co., Ltd. Melamine B1: Cymel 236 manufactured by Mitsui Cytec
(Butoxy group ratio 60%) Melamine B2: Cymel 235 manufactured by Mitsui Cytec
(Butoxy group ratio 40%) Melamine B3: Mycoat 506 manufactured by Mitsui Cytec
(Ratio of butoxy group: 100%) Melamine B4: Nikarac MX- manufactured by Sanwa Chemicals Co., Ltd.
40 (butoxy group ratio 30%)

A reactor having a stirrer, a thermometer, and a reflux cooling device was prepared.
Charge (1) to (8) according to the blending amount of 1
For 1 hour. After adding (9) to this, (1)
0) was gradually added to obtain a dispersion resin liquid. This resin dispersion was kept at 80 ° C. for 6 hours to terminate the microgelation reaction, and (11) was added to the resin dispersion.
11 was obtained.

Preparation of Paint and Electrodeposition Coating [Examples 1 to 7 Comparative Examples 1 to 4] Using the dispersion resin liquids obtained in Production Examples 1 to 11, using the formulations shown in Tables 3 and 4, A bath was obtained. This electrodeposition bath solution was put into a PVC bath, the cathode was made of SUS304 steel plate, and the 6063S aluminum alloy plate was subjected to alumite treatment (alumite film thickness = 9 μm), further electrolytically colored black, and then washed with hot water by a standard method. Electrodeposition coating was performed using an aluminum material as an anode (substrate).

[0043]

[Table 3]

[0044]

[Table 4]

Evaluation of coating film performance The specific conditions of electrodeposition coating were as follows: bath temperature 22 ° C., distance between electrodes 12c.
m, the pole ratio (+/-) 2/1, and 130
V was applied so that the coating thickness became 10 μm, and after the electrodeposition was completed, the coating was washed and subsequently baked at 185 ° C. for 30 minutes, and the coating performance was evaluated. Table 5 shows the results.

[0046]

[Table 5]

(Note) Evaluation method (1) Gloss value: 60 ° gloss was measured with a gloss meter. (2) Pencil hardness: JIS-K-5400 tear determination. (3) Make 100 grids on the coating film with a cutter knife, attach cellophane on it, and observe the adhesion when the cellophane tape is quickly peeled off. 100/100: No peeling. 0/100: All peeled off. (4) Alka resistance: Observation of the coated surface after immersion in 1% NaOH at 20 ° C for 48H. (5) Acid resistance: After immersing for 48 hours in 5% sulfuric acid at 20 ° C., the state of the coated surface was observed. (6) Appearance of coating film Dice mark ○: Dice mark is not conspicuous. Δ: Dice mark is slightly conspicuous. X: Dice mark is conspicuous. Smoothness ：: Good smoothness. ×: rough skin. (7) Gloss value at 70 ° C: After electrodeposition, dried at 70 ° C for 20 minutes and measured for gloss at 60 ° with a gloss meter. (8) Water washability: After electrodeposition, immerse in a 2% isopropyl alcohol aqueous solution for 3 minutes, pull up and leave for 3 minutes to observe the appearance. Further, baking is performed at 185 ° C. for 30 minutes, and the appearance of the coating film is observed. ：: No water repellency was observed during standing after immersion, and no streak-like gloss unevenness was observed in the coating film.

[0048]

The acid value is 30 to 100, and the hydroxyl value is 60 to 15.
An epoxy resin having an epoxy resin having an epoxy equivalent of 500 or less, an alkyl ether group having 4 to 10 carbon atoms having 40% or more of the total ether groups, and the remainder having a carbon number of 0 or less. By using an alkyl etherified methylol melamine resin having an alkyl ether group of 3 or less to form fine electrodepositable microgel particles in water, it has good electrophoresis and A matte electrodeposition paint having excellent uniform dispersibility and excellent uniform design was obtained.

Continuation of front page (72) Inventor Yasuhisa Saito 6-10-73 Minamitsukaguchi-cho, Amagasaki City, Hyogo Prefecture Inside Shinto Paint Co., Ltd.

Claims (6)

[Claims] (A) an acid value of 30 to 100 and a hydroxyl value of 60
Acrylic resin having a weight average molecular weight of 20,000 to 100,000, (B) alkyl etherification in which the amount of alkyl ether groups having 4 to 10 carbon atoms is 40% or more of all ether groups, and the remainder is alkyl ether groups having 3 or less carbon atoms A methylol melamine resin, and (C) an epoxy compound having two or more epoxy groups per molecule and having an epoxy equivalent of 500 or less, and in terms of solid content weight ratio,
A mixture in which (B) is 50 to 100 and (C) is 1 to 10 with respect to 100 of (A) is neutralized with a base to obtain an aqueous resin dispersion. A matte electrodeposition paint and a method of electrodeposition coating, comprising a resin composition obtained by a microgelation reaction at ℃. 2. The matte electrodeposition paint according to claim 1, wherein the alkyl ether group having 4 to 10 carbon atoms is (B) an alkyl etherified methylol melamine resin having 50% or more of the total ether groups. Electrodeposition method. 3. The matte electrodeposition coating composition according to claim 1, wherein the alkyl ether group having 4 to 10 carbon atoms is (B) an alkyl etherified methylol melamine resin having 50 to 80% of all ether groups. The electrodeposition coating method. 4. The method according to claim 1, wherein, in terms of solid content weight ratio, (B) the alkyl etherified methylol melamine resin is 70 to 90 and (C) the epoxy compound is 3 to 6, based on 100 of the acrylic resin. Matte electrodeposition paint and its electrodeposition coating method. 5. In terms of solid content weight ratio, (B) alkyl etherified methylol melamine resin is 70 to 90 and (C) epoxy compound is 3 with respect to (A) 100 acrylic resin.
The matte electrodeposition paint according to claim 2, wherein the composition is an electrocoating method. 6. An alkyl etherified methylol melamine resin (B) of 70 to 90 and an epoxy compound (C) of 3 to 6 based on 100 of the acrylic resin (A) in terms of solid content weight ratio. Matting electrodeposition paint and electrodeposition coating method described in 1.