JPH10183031A - Electrodeposition coating composition and coating film made by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the dullness, workability and film performance by using a carboxylated resin, fine inorganic particles and a specified alkylalkoxysilane compound (hydrolyzate) as the constituents. SOLUTION: A (oil-modified) saturated or unsaturated alkyd resin, or carboxylated resin such as carboxylated acrylic polymer in an amount of 100 pts.wt. is blended with fine inorganic particles having a mean diameter of 20-200nm, in an amount of 1-40 pts.wt. and an alkylalkoxysilane compound (hydrolyzate) having at least one group selected from amino, epoxy and isocyanato groups and represented by the formula X-R1 -SiO(R2 )3 (wherein R1 is a 2-10C alkyl or an aryl when X is amino; R1 is a 2-10C alkyl or an aryl when X is epoxy; and R1 is a 2-9C alkyl or an aryl when X is isocyanato), in an amount sufficient to provide a ratio of this compound to the acid value of resin of (1 to 10):1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeposition coating composition, and more particularly to an electrodeposition coating composition which can be suitably used as a matte coating film.

[0002]

2. Description of the Related Art Hitherto, many methods have been proposed for obtaining a matte electrodeposition coating film. For example, (1)
A method of washing the electrodeposited film with a cationic surfactant (see Japanese Patent Publication No. 48-4447), and a method of treating the electrodeposited film with an alcohol solution or an alcohol-containing aqueous solution (Japanese Patent Publication No. 46-22351). (3) a method of treating an electrodeposited coating film before baking with an aqueous solution of an organic acid or an inorganic acid (see JP-A-52-137444-6), and (4) an electrodeposition coating before baking. A method of treating the membrane with hot water or steam (Japanese Patent Publication No. 47-
A method is known in the art.

However, in the method of performing some treatment after forming the electrodeposition coating film, a sufficient matting effect cannot be obtained, or if the treatment liquid is not strictly controlled, the matting state varies from lot to lot, and Differences in texture, uneven matting, and mattness occur. In addition, since one step is added in the electrodeposition coating line, problems such as a decrease in work efficiency occur.

[0004] As a method of obtaining a matte coating film in general coating, a method of dispersing a matting agent in a paint has been widely practiced, and this method is applied to electrodeposition coating. Alternatively, a method of dispersing a matting agent in a water-soluble electrodeposition paint (see Japanese Patent Publication No. 60-8318), (6) a method of dispersing a silica fine powder in an aqueous or water-soluble electrodeposition paint (Japanese Patent Publication No.
No. 60-8319) and the like. In this,
The method of dispersing the silica fine powder in the aqueous or water-soluble electrodeposition paint can relatively easily disperse the silica fine powder in the paint, but the bond between the paint particles and the silica fine powder is not sufficiently generated, The gloss of the coating film greatly changes depending on the presence or absence of water washing after the electrodeposition coating, and the problem that the uneven gloss due to the uneven water washing becomes prominent tends to occur. Further, it is difficult to control the silica content in the paint and the silica content in the coating film to the same amount, and there is also a problem that the composition is greatly different between immediately after use of the paint and at the end thereof.

Further, in recent years, there has been proposed (7) an invention in which a molecule having an alkoxysilane group in a side chain is introduced into a resin to form a microgel to give a matting effect (Japanese Patent Publication No. Sho 62-24519).
Japanese Patent Application Laid-Open Publication No. 2000-216, the mainstream of matte electrodeposition paints. However, in this method, it is necessary to introduce an alkoxysilane group into the side chain of the resin, and a device must be devised for polymerization of the resin itself, and the alkoxysilane group is not introduced into the side chain of the resin molecule as expected. There are problems such as affecting. Furthermore, even though the alkoxysilane group can be introduced into the side chain as expected, the alkoxysilane group may not sufficiently stabilize the coating particles (resin molecules) forming the microgel. Therefore, instead of introducing alkoxysilane into the side chain, a method of adding 3-chloropropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, and phenyltriethoxysilane to the resin was attempted. No erasing effect was obtained.

As described above, the addition of an inorganic fine powder and the introduction of an alkoxysilane group have been proposed to impart a matting property. However, it is desired to improve the weather resistance of the resin and to reduce the defects of the coating film. I have.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide the above-mentioned drawbacks of the conventional matte electrodeposition coating film, that is, an electrodeposition coating composition having excellent matting properties, workability and high coating performance. An object and a coating film using the same are provided.

[0008]

The present invention has the following configuration to achieve the above object.

"(1) An electrodeposition paint comprising inorganic fine particles, an alkylalkoxysilane compound having at least one selected from an amino group, an epoxy group and an isocyanate group and / or a hydrolyzate thereof. Composition.

(2) A coating film obtained by curing the electrodeposition coating composition according to (1). "

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the inorganic fine particles are not particularly limited, but metal oxide fine particles and a sol obtained by finely dispersing them in a solvent are preferred. Metal oxide fine particles such as antimony oxide, aluminum oxide, titanium oxide, zirconium oxide, and molybdenum oxide, and their sols are preferably used. Further, calcium carbonate, clay, alumina white and the like can be added and used. Among them, a sol dispersed in a solvent of metal oxide fine particles is preferably used because of excellent stability and excellent miscibility with a resin, particularly, because the diameter of the dispersed particles can be easily controlled. Silicon oxide is preferably used. The size and shape are not limited, but the average particle diameter is 20.
Spherical or oblong particles of nm to 200 nm are particularly preferred. When the particle diameter exceeds 200 nm, sedimentation or secondary aggregation of the paint particles tends to occur, while when it is smaller than 20 nm, the matting effect tends to be insufficient.

In the present invention, as the alkoxysilane compound and / or its hydrolyzate, one having at least one selected from an amino group, an epoxy group and an isocyanate group is used. Among them, those having an amino group or an epoxy group are particularly preferable from the viewpoint of reactivity with the carboxyl group of the resin. As the alkylalkoxysilane compound, a generally used alkoxysilane compound is used. For example, in a compound represented by the following general formula, a compound in which X is substituted with an amino group, an epoxy group, or an isocyanate group is particularly preferable. It is preferably used.

The amino group of the formula XR ₁ -SiO (R ₂ ) ₃ is not particularly limited, but a primary amino group is particularly preferred. When X is an amino group, R ₁ is preferably an alkyl or aryl group having 2 to 10 carbon atoms. As the epoxy group, glycidyl, 1,3-epoxycyclohexyl, and the like are preferable. In this case, R1 is preferably an alkyl group or an aryl group having 2 to 10 carbon atoms. When X is an isocyanate group, R ₁ is preferably an alkyl or aryl group having 2 to 9 carbon atoms.

In the present invention, a resin having a carboxyl group is preferably used in the case of a paint used for anion electrodeposition using an object to be coated as an anode. Further, in the case of cationic electrodeposition using an object to be coated as a cathode, it is preferable to use a resin having a tertiary amino group in a side chain. As the resin having a carboxyl group, for example, (1) a mixture of one or more of a saturated or unsaturated alkyd resin and an oil-modified product thereof, an acrylic polymer having a carboxyl group, a vinyl polymer, and an acrylic vinyl copolymer Or, (2) a fluoropolymer having a carboxyl group, for example, by reacting a dibasic acid anhydride with a hydroxyl group-containing fluoropolymer and introducing a carboxyl group, such as a carboxyl generally used as an electrodeposition paint A resin having a group can be suitably used in the present invention.

Further, in the present invention, it is preferable to use an amine or ammonia from the viewpoint that the emulsion is stabilized, has low volatility, and hardly remains in the side chain. As the amine, trimethylamine, triethylamine,
Preferred are tertiary amines such as trialkylamines such as tripropylamine, hydroxyalkylamines such as triethanolamine and tripropanolamine, and aromatic amines such as benzyldimethylamine. On the other hand, in the case of cationic electrodeposition, it is also preferable to use a polymer compound having a tertiary amine in the side chain.

In the present invention, the inorganic fine particles are coated with an alkylalkoxysilane compound having at least one isocyanate group, an amino group and an epoxy group and / or a hydrolyzate thereof, whereby the inorganic fine particles are coated. Stable in the composition.

The use ratio of the inorganic fine particles of the present invention to the alkylalkoxysilane compound is 3 to 50 equivalents in terms of amino group, epoxy group and isocyanate group of the alkylalkoxysilane compound with respect to the inorganic fine particles. Is preferred.

The amount of the inorganic fine particles is preferably 1 to 40 parts by weight per 100 parts by weight of the resin having a carboxyl group. If the amount exceeds 40 parts by weight, the inorganic fine particles cannot be sufficiently mixed into the paint particles when dispersed in water to form a paint, and the inorganic fine particles may float in the aqueous dispersion medium. It tends to impair the appearance. If the amount of the inorganic fine particles is less than 1 part by weight, the matting effect of the electrodeposition coating film may be insufficient. Further, when the average particle diameter of the inorganic fine particles is from 20 nm to 200 nm, a particularly high effect can be obtained.

Particularly high effects are obtained when the alkylalkoxysilane compound of the present invention and / or its hydrolyzate is contained at a ratio corresponding to 1 to 10 of the resin acid value of the resin having a carboxyl group. If it exceeds 10, the paint particles are enlarged when dispersed in water to form a paint, and the paint particle system becomes non-uniform, which tends to impair the appearance of the electrodeposition coating film. If the amount is less than 1 part by weight, the matte effect of the electrodeposition coating film tends to be insufficient.

It is also preferable to add an appropriate amount of a melamine resin to the resin having a carboxyl group to further improve the boiling water resistance and alkali resistance of the electrodeposition coating film.

In forming a coating (dispersion in water), first, an alkylalkoxysilane compound having at least one selected from inorganic fine particles, amino groups, epoxy groups and isocyanate groups and / or a hydrolyzate thereof, for example, a carboxyl group What is added to a resin such as a resin having the resin is dispersed using water as a dispersion medium. At that time, the acid of the resin must be neutralized. For example, amines or ammonia is added. In this case, it is preferable to add amines or ammonia at an addition ratio corresponding to 60% to 90% neutralization of the acid value of the resin such as a resin having a carboxyl group. When the neutralization ratio is out of this range, the inorganic fine particles added to the resin at the time of coating, the alkylalkoxysilane compound and / or a hydrolyzate thereof tend to be separated from the resin.

The temperature at which the inorganic fine particles, the alkylalkoxysilane compound and / or the hydrolyzate thereof are mixed with the resin is preferably in the range of 0 ° C. to 100 ° C. When the temperature is low, the dispersion efficiency of the inorganic fine particles, the alkylalkoxysilane compound and / or the hydrolyzate thereof in the resin decreases, and when the temperature is high, the inorganic fine particles, the alkylalkoxysilane compound and / or the hydrolyzate thereof are reduced. Etc. may be metamorphosed.

The coating is preferably made within one week after mixing the inorganic fine particles, the alkylalkoxysilane compound and / or the hydrolyzate thereof, and the like. If left for a long time after mixing, the paint particles at the time of forming the paint may undergo secondary aggregation and settle.

Hereinafter, one embodiment of the electrodeposition coating composition of the present invention will be described.

In a temperature range of 0 ° C. to 100 ° C., 1 to 4 spherical silica fine particles are added to 100 parts by weight of the acrylic resin.
0 parts by weight (solid content) of an alkylalkoxysilane compound having an amino group or an epoxy group is added to 1 to 10 equivalents of the acrylic resin acid value, and triethylamine is added to 60% to 90% of the acrylic resin acid value equivalent to neutralization. These are sufficiently mixed and dispersed with a chemister. At this time, a melamine resin may be added in an appropriate amount to improve the performance of the electrodeposition coating film. After standing for one week immediately after mixing, deionized water is gradually added to prepare a matte electrodeposition coating stock solution having a resin solid content of 20 to 30% by weight. It is preferable to gradually add deionized water to the adjusted stock solution to make the resin solid content of the electrodeposition coating material 3 to 20% by weight, and then to perform the electrodeposition coating. If the resin solid content is outside this range, unevenness during coating, weather resistance,
The acid resistance tends to be insufficient.

Hereinafter, the present invention will be described in more detail with reference to Examples.

[0027]

【Example】

Examples 1-4 An acrylic resin (acid value 550.5, hydroxyl value 8
6.0, solids content 53.4% by weight, solvent composition normal butanol 18.3% by weight, isopropanol 28.3% by weight), silica fine particles (trade name IPA-ST, manufactured by Nissan Chemical Co., Ltd.), γ-glycidoxy Propyltrimethoxysilane (trade name KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed with a resin acid value of 6 and triethylamine was mixed with 60% neutralization of the resin acid value. After leaving for 3 hours, deionized water was gradually added. A matte electrodeposition coating stock solution having a resin solid content of 25% by weight was prepared. The amount of the acrylic resin, the amount of added silica fine particles, the amount of γ-glycidoxypropyltrimethoxysilane, and the amount of triethylamine added are as shown in Table 1. The acrylic resin was 100 parts by weight in terms of solid content.

Further, the obtained resin composition was adjusted with deionized water to obtain a resin solid content of 10% by weight.

An aluminum test plate (trade name: A6063S, manufactured by Nippon Test Panel Kogyo Co., Ltd.) that has been subjected to anodizing treatment in each of the prepared paints is held in a vertically suspended state.
Using this as an anode, the voltage was adjusted so that the coating thickness became 14 μm, and a direct current was applied for 150 seconds. After the coating was completed, the test plate was removed from the paint bath, drained for 90 seconds, washed with water, and then placed in a hot-air circulation oven and dried by heating at 180 ° C. for 30 minutes. The gloss and appearance of the obtained electrodeposition coating film,
The weather resistance, acid resistance, pencil hardness and co-progression properties were as shown in Table 1. The co-progressive property indicates the ratio of the content of silica in the electrodeposition paint to the content of silica in the electrodeposition coating film. The silica content in the figure is shown. The silica content in the coating film was measured by scraping a fixed weight of the electrodeposited coating film with a scraper, placing it in a crucible, heating the crucible to about 1000 ° C., and calculating the remaining amount when the weight became constant. Was calculated.

Example 5 An electrodeposited coating film was obtained in the same manner as in Example 2, except that water washing was not performed after the electrodeposition coating. The performance of the obtained electrodeposition coating film was as shown in Table 1.

Example 6 In Example 2, the silica fine particles used were changed to trade name NB
An electrodeposition coating film was obtained by using the same method except that A-ST (manufactured by Nissan Chemical Industries, Ltd.) was used. The performance of the obtained electrodeposition coating film was as shown in Table 1.

Example 7 The same procedure as in Example 2 was carried out except that γ-glycidoxypropyltriethoxysilane was changed to γ-glycidoxypropyltriethoxysilane (trade name KBE-403, manufactured by Shin-Etsu Chemical Co., Ltd.). Was used to obtain an electrodeposition coating film. The performance of the obtained electrodeposition coating film was as shown in Table 1.

Example 8 The procedure of Example 2 was repeated except that the melamine resin (trade name Nikalac M) was used.
X-57, manufactured by Sanwa Chemical Co., Ltd.) was used in the same manner except that acrylic resin, silica fine particles, and γ-glycidoxypropyltrimethoxysilane were simultaneously added to obtain an electrodeposition coating film. The obtained electrodeposition coating film was as shown in Table 1.

Comparative Example 1 An electrodeposited coating film was obtained in the same manner as in Example 1 except that silica fine particles were not added. The performance of the obtained electrodeposition coating film was as shown in Table 1.

Comparative Example 2 An electrodeposited coating film was obtained in the same manner as in Example 2 except that γ-glycidoxypropyltrimethoxysilane was not used. The obtained electrodeposition coating film was as shown in Table 1.

Comparative Example 3 An aluminum test plate (trade name: A6063S, manufactured by Nippon Test Panel Kogyo Co., Ltd.) obtained by anodizing the paint obtained in Example 1 was dip-coated and air-dried at room temperature for 30 minutes.
It was placed in a hot air circulation oven and dried by heating at 180 ° C. for 30 minutes. The resulting coating had a gloss value of 90 and was not a matte coating.

[0037]

The electrodeposition coating composition of the present invention exhibits extremely stable matting performance irrespective of the presence or absence of washing with water. In addition, in terms of co-progression, the inorganic fine particles are immobilized by the alkylalkoxysilane compound and / or a hydrolyzate thereof, and thus have extremely excellent stability.

Claims (8)

[Claims] An electrodeposition coating composition comprising inorganic fine particles, an alkylalkoxysilane compound having at least one selected from an amino group, an epoxy group and an isocyanate group and / or a hydrolyzate thereof. . 2. The electrodeposition coating composition according to claim 1, comprising an amine or ammonia. 3. The electrodeposition coating composition according to claim 1, further comprising a resin having a carboxyl group. 4. The electrodeposition coating composition according to claim 3, wherein the composition contains 1 to 40 parts by weight of inorganic fine particles per 100 parts by weight of the resin. 5. An alkylalkoxysilane compound and / or
5. The electrodeposition coating composition according to claim 3, wherein a hydrolyzate thereof is contained in an amount of 1 to 10 corresponding to the acid value of the resin. 6. The electrodeposition coating composition according to claim 2, wherein the composition contains an amine or ammonia corresponding to a neutralization of 60% or more and 90% or less of the acid value of the resin. 7. A coating film obtained by curing the electrodeposition coating composition according to claim 1. 8. The coating according to claim 7, wherein the gloss of the coating is 5 or more and 40 or less.