JPH02269780A - Aqueous dispersion and matte electrodeposition coating composition - Google Patents

Abstract

PURPOSE:To prepare an electrodeposition coating compsn. having an excellent storage stability and giving a matte coating film with an excellent aesthetic appearance by compounding a reaction product of acrylic polycarboxylic acid resin with an epoxysilane compd. as the essential component. CONSTITUTION:100 pts.wt. acrylic polycarboxylic acid resin having an acid value of 20-200, pref. 30-100, a hydroxyl value of 200 or lower, pref. 20-100, and a number-average MW of 100-100000, pref. 200-80000, is reacted with 0.1-20 pts.wt., pref. 0.5-10 pts.wt., epoxysilane compd. (e.g. gamma- glycidoxypropylmethyldiethoxysilane). The reaction product is dispersed in water in a solid content of 3-60wt.%, pref. 7-45wt.% to give an electrodeposition coating compsn.

Description

[Detailed description of the invention] 1 mouse upper concave ■month! The present invention relates to aqueous dispersions and matte electrodeposition coating compositions.

' - Biso・ Conventionally, a product obtained by heating an aqueous emulsion containing an α,β-ethylenically unsaturated carboxylic acid resin and an epoxy compound has been used as a resin composition for a matte paint. It is described in Japanese Patent Application Laid-Open No. 58-213058.

This resin composition forms a matte coating film with excellent smoothness by reacting a carboxylic acid resin and an epoxy compound within the water-based emulsion particles and increasing the molecular weight to an appropriate level. Because strong acidic catalysts such as acid compounds and water-insoluble neutralizers are used, the molecular weight of the emulsion particles increases during long-term running, resulting in emulsion particles with no fluidity when baked and resulting in poor coating film smoothness. There were drawbacks.

As a result of extensive research in order to solve the above-mentioned problems, the inventors of the present invention have developed an electrodeposited material containing a reaction product of an acrylic polycarboxylic acid resin and an epoxysilane compound as an essential component. The present inventors have discovered that the coating composition has excellent storage stability and forms a matte coating film with excellent cosmetic properties, and has completed the present invention.

That is, the present invention provides a matting aqueous dispersion containing a reaction product of an acrylic polycarboxylic acid resin and an epoxysilane compound as a resin component, and a matting electric dispersion containing the aqueous dispersion as a matting agent component. The present invention relates to a coating composition.

As the acrylic polycarboxylic acid resin used in the present invention, conventionally known anionic acrylic electrodeposition paint resins and the like can be used. Specifically, for example, a polymer obtained by radical polymerization of a carboxyl group-containing polymerizable unsaturated monomer, optionally a hydroxyl group-containing polymerizable unsaturated monomer, and other radically polymerizable unsaturated monomers. Combination is preferred.

Examples of the carboxyl group-containing polymerizable unsaturated monomer include (meth)acrylic acid, (anhydrous) maleic acid, fumaric acid, crotonic acid, and itaconic acid. A carboxyl group is introduced into the polymer by the monomer component, and the carboxyl group is utilized for reaction with the epoxy group in the epoxysilane compound and for making the polymer water-soluble. The amount of the carboxyl group-containing polymerizable unsaturated monomer used is such that the acid value of the polymer is about 20 to 200, preferably about '30.
It is preferable to use the range of 100 to 100. If the acid value is less than about 20, the content of remaining carboxyl groups consumed by the epoxy silane compound will be small (and the stability of the aqueous dispersion will be poor).On the other hand, if the acid value is greater than about 200, the durability of the coating film will be poor. It is not preferable because it is inferior in quality.

Examples of the above-mentioned hydroxyl group-containing polymerizable unsaturated monomers include 2-hydroxyethyl (meth)acrylate and 2-hydroxybrobyl (meth)acrylate. A hydroxyl group is introduced into the polymer by the monomer component, and the hydroxyl group can be used to react with a crosslinking agent such as an amino resin and a blocked isocyanate compound to obtain a cured coating film. The content of hydroxyl groups is preferably in the range of 200 to 100, preferably 200 to 100.

As the above-mentioned amino resin, formaldehyde adducts of melamine, urea, benzoguanamine, acetoguanamine, or mixtures thereof and alcohol etherified products thereof are used, and the amino resin does not need to be water-soluble. Blocked polyisocyanate is a polyisocyanate compound reacted with a blocking agent (e.g. alcohol, phenol, etc.), and examples of the isocyanate compound include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, and metaxyl diisocyanate. , hexamethylene diisocyanate, lysine diisocyanate, 4.4'
-methylenebis(cyclohexyl isocyanate), methylcyclohexane 2.4 (2,6) diisocyanate, 1,3-(incyanatomethyl)cyclohexane, isophorone diisocyanate, trimethylhexamethylene diisocyanate, and the like.

The above-mentioned amino resin and block polyisocyanate may be used alone or in combination. The amount used is 50% by weight or less in terms of resin solid content.

Other radically polymerizable unsaturated monomers mentioned above include 5
For example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, etc. of(
Alkyl C1-24 esters of meth)acrylic acid; Vinyl aromatic monomers such as styrene, α-methylstyrene, and vinyltoluene; Amide compounds of acrylic acid or methacrylic acid; Usually used in the synthesis of acrylic resins such as acrylonitrile and methacrylonitrile Any known monomer can be used. These monomers can be appropriately selected and used depending on the required performance.

The above-mentioned acrylic polycarboxylic acid resin has approximately 1,000
~ioooooo, preferably about 2000-5oooo
can have a number average molecular weight in the range of . If the molecular weight is less than about 1000, a sufficient matting effect cannot be obtained,
On the other hand, if the molecular weight is greater than about 1 ooooo, the resin becomes highly viscous, making it difficult to form uniform fine particles during water dispersion, and storage stability tends to be poor, which is not preferable.

The epoxysilane compound used in the present invention has a number average molecular weight of about 130 to 9000, each having an average of one or more epoxy groups and a hydroxysilane group and/or a hydrolyzable group directly bonded to a silicon atom in one molecule; Preferably, it has a range of about 130 to 1000.

The hydrolyzable group directly bonded to the silicon atom is a residue that is hydrolyzed by water or moisture to produce a hydroxysilane group, such as a hydrogen atom: a C1-S alkoxy group;
Aryloxy groups such as phenoxy, tolyloxy, varamethoxyphenoxy, varanitrophenoxy, benzyloxy; acetoxy, propionyloxy, butanoyloxy, benzoyloxy, phenylacetoxy, formyloxy, etc. Acyloxy group;
Examples include residues represented by the following formula % formula % (R is the same or different and represents a C+"s alkyl group). Among them, alkoxy and acyloxy groups are suitable.

One or more epoxy groups and hydroxy groups and/or
Or as an epoxysilane compound having a hydrolyzable group directly bonded to a silicon atom, for example, OCR.

(:, H2-CH-CHz-0-CsHa-5L-OC
Hs\ / 1 0 0CH.

CH.

CR3 CH.

O.C., H.

CCHs CH2-CH-CH, -0-C,, Hs-SL-OCC
I3QC)I.

Hs 0CCI.

Epoxysilane compounds such as; such epoxysilane compounds and polysilane compounds (e.g. tetramethoxysilane, tetrapropoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, propyltripropoxysilane, dimethyldimethoxysilane, diethyljethoxysilane, dipropyl dimethoxysilane); Epoxypolysilane compounds obtained by reacting propoxysilane, diethyldisilanol, diphenyljethoxysilane, etc. with epoxy group-containing polymerizable unsaturated monomers (e.g. glycidyl (meth)acrylate, allyl glycidyl ether, 3.4- Polymerizable unsaturated monomers having a hydroxysilane group and/or a hydrolyzable group directly bonded to a silicon atom (e.g. vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyl Copolymers containing trimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, 2-styrylethyltrimethoxysilane, γ-(meth)acryloxib-vinyltrimethoxysilanol, etc. as essential monomer components. can be mentioned. Among these, it is preferable to use an epoxysilane compound which is used in a small amount (and forms a matte coating film with excellent cosmetic properties).

The above-mentioned epoxysilane compounds can be used alone or in combination of two or more.

The amount of the epoxy silane compound used is about 0.1 to 20 parts by weight, preferably about 0.5 to 10 parts by weight, based on ioo parts by weight of the acrylic polycarboxylic acid resin. If the amount used is less than about 0.1 parts by weight, a sufficient matte coating film cannot be obtained, while if the amount used is more than about 20 parts by weight, the stability of the aqueous dispersion will deteriorate, which is not preferred.

The aqueous dispersion of the present invention can be prepared, for example, by adding the crosslinking agent and the epoxysilane compound after or before neutralizing a solution of an acrylic polycarboxylic acid resin dissolved in an organic solvent with a neutralizing agent. When added, it can be adjusted by neutralizing, dispersing in water, and then heating to carry out the reaction.

As the organic solvent, it is preferable to use an organic solvent that is capable of dissolving or dispersing the acrylic polycarboxylic acid resin, does not easily react with the epoxysilane compound, and is hydrophilic. Specifically, for example, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, and butyl alcohol, cellosolve solvents such as ethylene glycol monomethyl, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether, and propylene glycol ethers. , diethylene glycol ethers, etc. can be used.

Further, as the neutralizing agent, conventionally known basic compounds can be used, such as ammonia, dimethylamine, trimethylamine, diethylamine, triethylamine, diisopropylamine, butylamine, monoethanolamine, jetanolamine, triethanolamine. , monoisopropanolamine, diisopropanazine, triisopropanazine, N-methylethanolamine, N-aminoethylethanolamine,
Examples include N-methyljetanolamine and polygutucolamine. These neutralizing agents have a ratio of about 0.3 to 1.2 to the carboxyl group of the acrylic polycarboxylic acid resin.
It can be used within the equivalent range.

The solids content of the aqueous dispersion is usually adjusted to about 3 to 60% by weight, preferably about 7 to 45% by weight.

The reaction of the aqueous dispersion is completed by raising the temperature of the aqueous dispersion to about 0° C. to reflux temperature and stirring.

In addition to the above, the aqueous dispersion of the present invention can be prepared by neutralizing an organic solvent solution of acrylic polycarboxylic acid resin with a neutralizing agent or by adding an epoxysilane compound to the neutralizing agent and performing a reaction. Furthermore, when a neutralizing agent is not added, after the neutralizing agent is added, a crosslinking agent is blended as needed, and this can be adjusted by dispersing this in water.

The above reaction can usually be carried out by raising the temperature from about 0°C to reflux temperature.

In the present invention, the reaction between the acrylic polycarboxylic acid resin and the epoxysilane compound can be controlled by measuring the resin acid value or epoxy equivalent. It is believed that it is sufficient that the resin acid value is reduced by about 1 or more from the initial resin acid value.

The aqueous dispersion obtained in this manner can be used as an electrodeposition paint by itself, or it can be used as a matting agent and mixed with a glossy electrodeposition paint.

As the glossy electrodeposition paint, conventionally known anionic electrodeposition paints, such as acrylic-melamine type, acrylic-isocyanate type, fluorine-melamine type, fluorine-isocyanate type, etc., can be used. .

The mixing ratio of the coated electrodeposition paint and the aqueous dispersion can be adjusted as appropriate depending on the required gloss, but usually the resin solid content of the aqueous dispersion is 10 parts by weight based on 100 parts by weight of the resin solid content of the paint. It can be used in an amount of at least 20 parts by weight, preferably at least 20 parts by weight.

The matte electrodeposition coating composition of the present invention may contain coloring pigments, extender pigments, coating surface conditioners, etc., if necessary.

The matte electrodeposition coating composition of the present invention usually has a resin type C content of about 3
It is prepared in a range of 20% by weight, preferably about 5% to 15% by weight, and subjected to electrodeposition coating.

As the method and apparatus for coating with the matte electrodeposition coating composition of the present invention, any known method and apparatus conventionally used in anodic electrodeposition can be used. The conditions for close contact secretion used are generally a bath temperature of 20°C.
~30℃, electric B100~400V (preferably 100
~30 Cv) and a current application time of 30 seconds to 10 minutes. A dry coating thickness of approximately 2 to 5 Cμ, preferably approximately 5 to 30 μ, is considered sufficient.

In addition, as a coating material to be electrodeposited, it also has electrical conductivity.
Materials, such as iron, steel, copper, aluminum, plating W4 base where the surface of steel is plated with zinc, tin, chromium, aluminum, etc., metal materials whose surface is chemically or electrolytically treated with chromic acid, phosphoric acid, etc. Can be mentioned. Among these, articles of various shapes (for example, plate-like, rod-like, enamel-like, etc.) made of anodic oxidized aluminum are preferred.

After the electrodeposition coating film formed on the object to be coated is pulled up from the electrodeposition bath, excess paint adhering to the electrodeposition coating film is washed with water or water passed through by reverse osmosis. Usually about 1
Baking is carried out at 50-220' C1, preferably at about 160-200 DEG C. for about 10-60 minutes, preferably for about 20-40 minutes.

(Action and Effect of the Invention) In the present invention, an epoxysilane compound reacts with an acrylic polycarboxylic acid resin to introduce a silane group into the resin, and the silane group is hydrolyzed in the process of water dispersion to form a hydroxysilane group. is formed, and then a condensation reaction between these groups or between these groups and a hydrolyzable group results in an intraparticle gel structure, and since there are many hydrophilic hydroxysilane groups on the particle surface, fine and stable water is formed. Forming dispersed particles. The coating film obtained by electrocoating this product is highly hydrophilic, so remove excess electrocoating paint with water, etc. (It is a matte coating film that has good suitability for washing with water and has no finishing defects after washing.) In addition, when baking the electrodeposition coating, polysiloxane bonds are generated by the reaction between hydroxyl groups on the particle surface, resulting in a matte coating with excellent weather resistance, chemical resistance, etc. be able to.

The present invention will now be described in more detail. "Parts" and "%" in the examples are based on weight.

Example 1 100 parts of isopropyl alcohol was charged into a reaction vessel and maintained at 80°C, and 18 parts of styrene, 31 parts of methyl methacrylate, 19 parts of n-butyl acrylate, 810 parts of ethyl acrylate, 15 parts of hydroxyethyl acrylate, and acrylic acid were added. A mixture of 7 parts of azobisdimethylvaleronitrile and 1.0 parts of azobisdimethylvaleronitrile was added dropwise over 3 hours to carry out a reaction. An acrylic copolymer varnish having a number average molecular weight of 30,000, an acid value of 53, and a hydroxyl value of 72 was obtained.

Next, 42 parts of methylmethylolated melamine resin (manufactured by Hitachi Chemical Co., Ltd., Melan 620, solid content 70%) and 5 parts of γ-glycidoxypropyl methyljethoxysilane were added to 140 parts of the above varnish. , mixed well to make it homogeneous. Add 857 parts of deionized water to the mixture;
After adjusting the solid content to 10%, it was heated for 70' while stirring.
The reaction was carried out at C for 4 hours to obtain the electrodeposition paint of Example 1.

Example 2 Example 2 was carried out using the same formulation and manufacturing method as in Example 1, except that γ-glycidoxypropylmethyljethoxysilane used in Example 1 was replaced with γ-glycidoxypropyltrimethoxysilane. An electrodeposited paint was obtained.

Example 3 The γ-glycidoxypropylmethyljethoxysilane used in Example 1 was converted into β-(3,4 epoxycyclohexyl)
Example 1 except that it was replaced with ethyltrimethoxysilane
The electrodeposition paint of Example 3 was obtained using the same formulation and manufacturing method.

Example 4 A mixture of 140 parts of the acrylic copolymer varnish and 5 parts of γ-glycidoxypropylmethyljethoxysilane was reacted at 80° C. for 4 hours to obtain a reaction product. Next, the reaction mixture was cooled to room temperature, 42 parts of Melan 620 was added, and the mixture was thoroughly mixed to become uniform. Add 8 ounces of deionized water to the mixture.
57 parts were added to obtain the electrodeposition paint of Example 4 having a solid content of 10%.

Example 5 Anionic glossy electrodeposition paint (manufactured by Kansai Paint Co., Ltd., AG-
200, acrylic-melamine paint, solid content 10%
) 700 parts of the electrodeposition paint of Example 1 (solid content 1O%) 30
0 parts was added thereto and mixed thoroughly to obtain a uniform electrodeposited paint of Example 5.

Comparative Example 1 An electrodeposition paint of Comparative Example 1 was obtained using the same formulation and manufacturing method as in Example 1, except that the γ-glycidoxypropylmethyljethoxysilane used in Example 1 was not used.

Comparative Example 2 The same formulation and production as in Example 1 except that 5 parts of γ-glycidoxypropyl methyljethoxysilane used in Example 1 was replaced with 10 parts of epoxy resin (Epicoat 834, manufactured by Shell Chemical Co., Ltd.). An electrical storage paint of Comparative Example 2 was obtained by the method.

An anodized 6063S aluminum alloy plate (anodized film thickness 10μ) is used as the object to be coated (anode),
In the electrodeposition paint baths of the above Examples and Comparative Examples, the bath temperature was 22°C;
The applied voltage was set so that the dry film thickness was about 10μ, and electricity was applied for 3 minutes to form an electrodeposited film on the object to be coated.After washing with water, baking was carried out at 180℃ for 30 minutes. I got a painted plate.

Paint storage stability: After being left in a sealed state at 30℃ for 2 months, electrodeposition coating was performed and the appearance of the coating film was compared with that before the test.
Changes in the appearance of the paint film were observed.

Painted surface smoothness: The appearance of the painted film after painting was observed with the naked eye to check for citrus skin, pinholes, unevenness, and appearance.

Gloss: Gloss meter (E!' VG2PD manufactured by Hondenshoku Kogyo Co., Ltd.
) was used to measure the specular reflectance (unit: 2%) at 60 parts.

Goban adhesion: Make 100 1 mm square creases in the coating film with a cutter knife, and cut 100 creases with cellophane adhesive tape.
A peel test was conducted to determine the number of remaining folds.

After being immersed in an aqueous solution of sodium hydroxide having alkali resistance of 1% by weight for 72 hours, the appearance of the coating film was observed with the naked eye to determine the presence or absence of blistering.

(○: No abnormality, @: Slight blistering, Δ niblistering, ×: Significant blistering) Weather resistance: Weather meter (manufactured by Suga Test Instruments Co., Ltd., Ducycle, 60 minutes of irradiation/60 minutes of darkness, black An accelerated weathering test was conducted for 100 hours at a panel temperature of 63°C.
The gloss retention rate (unit: 2%) and appearance were examined.

Claims (2)

[Claims] (1) A mattable aqueous dispersion containing a reaction product of an acrylic polycarboxylic acid resin and an epoxysilane compound as a resin component. (2) A matte electrodeposition coating composition containing the aqueous dispersion according to claim 1 as a matting agent component.