JPH10128226A - Formation of coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method of a coating film excellent in smoothness, iridescent luster, water resistance, acid resistance, scuff resistance, etc., and less susceptible to a humidity at the time of coating. SOLUTION: In the coating film forming method, a thermoset org. solvent based coloring base coating material A containing a neutralized matter of a hydroxy group-containing resin having an acid value of 5-100, a blocked polyisocyanate and a crosslinking agent selected from among blocked polyisocyanates and amino resins is applied, and a thermoset water based coating material B is applied on the uncured coloring coated surface. After applying a thermoset org. solvent based clear coating material C containing a carboxyl group-containing resin, a vinyl polymer having an epoxy group, a hydroxy group and a hydrolyzable alkoxysilyl group in one molecule, a reactive organopolysiloxane and a crosslinked fine particles polymer and having 65-90wt.% solid content, a three-layered coating film consisting of the components A, B and C is cured simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a three-layer coating film using a colored base paint, a water-based colored paint and a clear paint.

[0002]

2. Description of the Related Art A neutralized polycarboxylic acid resin having an acid value of 5 to 100 and an amino resin are essential components, and an organic solvent-based thermosetting paint containing no metallic pigment is applied. The viscosity of the applied paint is 10 poise (20
It is known that the above three-layer coating is heated and cured simultaneously after adjusting the temperature to at least (° C), applying a thermosetting aqueous metallic coating thereon, and further applying a transparent thermosetting coating. (Japanese Patent Publication No. 4-25076). By the way, the type of the top coat paint for automobile outer panels and the like which has conventionally been mainly of a type in which a hydroxyl group-containing acrylic resin is cured by heating with a melamine resin. However, in recent years, etching of a coating film and stain-like stains due to acid rain have become problems worldwide. Further, with the spread of car wash machines, abrasion caused by the car wash machines has also become a problem. For this reason, there is a demand for a topcoat paint, particularly a clear topcoat paint, which can form a coating film having both sufficient acid resistance and abrasion resistance.

[0003] The imparting of scratch resistance to a coating film is usually achieved by making the coating film highly crosslinked. On the other hand, imparting acid resistance to a coating film is usually achieved by introducing a crosslinking system resistant to acid. However, almost no method has been proposed so far to impart acid resistance to the coating film while also imparting scratch resistance.

Further, in the field of paints, it is urgently necessary to take measures to control the use of solvents due to aggravation of air pollution and to save resources by reflecting on waste of resources.

As one of the measures, there is a development of a so-called high solid content paint in which the content of a solvent in the paint is reduced to increase the solid content. Most of the high solid content paints currently being developed are aminopolyester-based and aminoacrylic-based paints using an amino resin as a curing agent, but desired ones have not been obtained due to the following disadvantages. . First, if these resins are reduced in molecular weight in order to reduce the viscosity of amino resins, polyesters and acrylic resins, a crosslinkable functional group (such as amino resins) Must have a high content of a methylol group, an imino group, a polyester and an acrylic resin, and a hydroxyl group. However, these crosslinkable functional groups tend to increase the viscosity due to the interaction between the functional groups, and hinder lowering the viscosity. Particularly, in the case of an acrylic resin, it is necessary to compensate for a decrease in the performance of the coating film due to a decrease in the molecular weight by a large amount of hydroxyl groups. Second, when an amino resin paint is used as the high solid content paint, it is thought to be due to the fact that a large amount of condensate such as alcohol is generated at the time of baking and curing. . Therefore, the tendency of the amino resin paint to cause this “sidearm” is a drawback to high solid differentiation of the paint.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a method for forming a coating film which solves the above-mentioned deficiencies of the above method and has excellent acid resistance and scratch resistance.

That is, the present invention relates to a thermosetting organic solvent system containing a neutralized product of a hydroxyl group-containing resin having an acid value of 5 to 100 and a crosslinking agent selected from a block polyisocyanate and an amino resin. A colored base paint (A) is applied, a thermosetting water-based colored paint (B) is applied to the uncured colored coating surface, and if necessary, preliminarily dried at 50 to 100 ° C. 1) a resin having a carboxyl group, (C-
2) A vinyl polymer having an epoxy group, a hydroxyl group and a hydrolyzable alkoxysilyl group in one molecule, (C-3) a reactive organopolysiloxane, and (C-4) a crosslinked fine particle polymer. Characteristic solid content is 65-
After applying 90% by weight of a thermosetting organic solvent-based clear coating material (C), it is heated and heated to the above (A), (B) and (C).
And a method of forming a three-layer coating film comprising:

Hereinafter, the coating film forming method (the present method) of the present invention will be described in detail.

Colored base paint (A): acid value of 5 to 100
A thermosetting organic solvent-based coloring paint containing a neutralized product of a hydroxyl group-containing resin and a crosslinking agent selected from a block polyisocyanate and an amino resin. This is a liquid paint to be applied to an object to be coated prior to the application.

The colored base paint (A) has an acid value of 5 to 10
A crosslinked agent (A-2) and a color pigment (A-3) selected from a neutralized product of the hydroxyl group-containing resin (A-1), block polyisocyanate and amino resin, which are 0, as essential components; Is a thermosetting organic solvent-based colored coating obtained by mixing the above with an organic solvent.

(A-1) is a hydroxyl group-containing resin having an acid value of 5 to 100, and has a carboxyl group and a hydroxyl group in one molecule.

[0012] The content of the carboxyl group is in the range of 5 to 100 mgKOH / g based on the acid value.
-70 mgKOH / g, particularly preferably 30-50 mg
KOH / g is preferred. When the acid value is less than 5 mgKOH / g, the coating with the water-based colored coating (B) to be subsequently coated is poor and the ability to absorb moisture in the coating is inferior. , Sauce, etc.,
On the other hand, when the acid value is larger than 100, the water resistance of the coating film of the coating material (A) is lowered, and neither is preferable.

The hydroxyl group in the resin (A-1) imparts crosslinking reactivity with the crosslinking agent (A-2), and its content is from 10 to 150 mgKOH / g based on the hydroxyl value.
Particularly, 30 to 80 mgKOH / g is preferable.

Specific examples of the resin (A-1) include acrylic resins, vinyl resins and polyester resins having a carboxyl group and a hydroxyl group.

[0015] The acrylic resin and the vinyl resin are polymers comprising a carboxyl group-containing unsaturated monomer and a hydroxyl group-containing unsaturated monomer as main components, and further using other unsaturated monomers as required. Having a number average molecular weight of about 3,000 to 100,000, especially about 5,000 to 5
000 is preferred.

The carboxyl group-containing unsaturated monomer is a compound having at least one polymerizable unsaturated double bond and at least one carboxyl group in one molecule, for example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid. Examples include acids and half-monoalkyl esters of these dicarboxylic acids (suitably having 1 to 10 carbon atoms), and one or more of these can be used.

The hydroxyl group-containing unsaturated monomer has at least one polymerizable unsaturated double bond and at least one hydroxyl group in one molecule.
Compound, for example, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, acrylic acid or methacrylic acid such as hydroxypropyl methacrylate and 2 to 2 carbon atoms
Monoesters with 10 glycols, and the like, and one or more of these can be used.

The other unsaturated monomer is a compound having at least one polymerizable unsaturated double bond in one molecule, and is an unsaturated monomer having no carboxyl group or hydroxyl group. Specifically, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate,
Butyl acrylate, butyl methacrylate, pentyl acrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate,
Monoesters of acrylic acid or methacrylic acid such as lauryl acrylate and lauryl methacrylate with monoalcohols having 1 to 24 carbon atoms; glycidyl group-containing unsaturated monomers such as glycidyl acrylate and glycidyl methacrylate; acrylonitrile, acrylamide, N-methyl Nitrogen-containing unsaturated monomers such as acrylamide, N-methylolacrylamide, N-butoxymethylacrylamide and dimethylaminoethyl methacrylate; aromatic ring-containing unsaturated monomers such as styrene, α-methylstyrene and vinyltoluene; vinyl acetate; Vinyl chloride; and one or more of these can be used.

The acrylic resin is a polymer containing 20% by weight or more of monoesters of acrylic acid or methacrylic acid and a monoalcohol having 1 to 24 carbon atoms, and the vinyl resin has a content of 20% by weight of the monoesters. Less than the polymer.

The polyester resin is an oil-free or oil-modified oil-prepared resin prepared by an ester reaction using a polyhydric alcohol and a polybasic acid, and if necessary, a monobasic acid and an oil component (including this fatty acid). It is a polyester resin. The number average molecular weight of the resin is about 500
~ 50,000, especially about 3,000-30,000 are preferred.

Polyhydric alcohols are compounds having two or more hydroxyl groups in one molecule, such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, 2,2-dimethylpropanediol, glycerin, and trimethylolpropane. And pentaerythritol and Kajura E (trade name, manufactured by Shell Chemical Co., Ltd.), and one or more of these can be used. A polybasic acid is a compound having two or more carboxyl groups in one molecule, for example, phthalic acid, isophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, succinic acid, adipic acid, sebacic acid, trimellitic acid Examples thereof include acids, pyromellitic acid and anhydrides thereof, and one or more of these can be used.

The monobasic acid is a compound having one carboxyl group in one molecule and includes, for example, benzoic acid and t-butylbenzoic acid. The oil component (including this fatty acid) is castor oil, dehydrated Castor oil, safflower oil,
Examples include soybean oil, linseed oil, tall oil, coconut oil, and fatty acids thereof, and one or more of these can be used.

In the polyester resin, the carboxyl group may be, for example, a polycarboxylic acid such as trimellitic acid and pyromellitic acid having three or more carboxyl groups in one molecule, or a dicarboxylic acid may be half-esterified. And the hydroxyl group is glycerin,
It can be easily introduced by using a polyhydric alcohol having three or more hydroxyl groups in one molecule such as trimethylolpropane or pentaerythritol.

As the resin (A-1), a graft polymer obtained by grafting an acrylic resin or a vinyl resin to a polyester resin can also be used, and its number average molecular weight is 500 to 4
000 is suitable. The graft polymer is obtained by reacting the above unsaturated monomer with a polyester resin having a polymerizable unsaturated group.

The resin (A-1) used in the colored base coating material (A) neutralizes the carboxyl groups of the resin (A-1) by using a basic substance before mixing with the crosslinking agent (A-2) or the like. Is preferred.

The basic substance for neutralization is preferably water-soluble, such as ammonia, methylamine, ethylamine, propylamine, isopropylamine, butylamine, 2-ethylhexylamine, cyclohexylamine, dimethylamine, diethylamine, dipropylamine, and the like. Diisopropylamine, dibutylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, ethylenediamine, morpholine, N-alkylmorpholine, pyridine, monoisopropanolamine, methylethanolamine, methylisopropanolamine, dimethylethanolamine, diisopropanolamine, diethanolamine, Triethanolamine, diethylethanolamine, triethanolamine, etc. Are, these are one or two
More than species can be used. The amount of these neutralizing agents used is 0.1 to 2.0 based on the carboxyl groups in the resin (A-1).
Equivalents, especially 0.3-1.2 equivalents, are suitable.

The crosslinking agent (A-2) is selected from a block polyisocyanate and an amino resin, and reacts with a hydroxyl group of the neutralized resin (A-1) to form a colored base coating material (A). The coating is cross-linked and cured in three dimensions.

The block polyisocyanate is a compound obtained by blocking the isocyanate group of a polyisocyanate compound with a blocking agent such as phenols, alcohols, oximes, lactams, etc. at a predetermined temperature (usually 80 to 1).
When heated above 60 ° C.), the blocking agent dissociates to regenerate free isocyanate groups, which undergo a crosslinking reaction with the hydroxyl groups of the resin (A-1).

The polyisocyanate compound contains 2 per molecule.
Compounds having at least two isocyanate groups, such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate, Free methylene bis (cyclohexyl isocyanate), isophorone diisocyanate, and free isocyanate groups obtained by reacting these polyisocyanates with low or high molecular weight polyols in excess of isocyanate groups. And prepolymers. The molecular weight of the block polyisocyanate is preferably from 200 to 10,000.

As the amino resin, for example, a methylolated amino resin in which an imino group obtained by condensation reaction of formaldehyde with a part or all of amino groups of an amino compound such as melamine, benzoguanamine or urea may remain; Further, imino groups or methylol groups obtained by etherification with one or more alcohols selected from monoalcohols having 1 to 10 carbon atoms remain in all or a part of the methylol groups of the methylolated amino resin. An alkyl etherified amino resin which may be used. The number average molecular weight of the alkyl etherified amino resin is preferably from 400 to 3,000.

The neutralized resin (A-1) and the crosslinking agent (A-
The ratio to 2) is based on the solid content, and the former is suitably 50 to 90% by weight, particularly 60 to 80% by weight, and the latter is suitably 50 to 10% by weight, particularly 40 to 20% by weight.

The color pigment (A-3) is for coloring the coating film of the colored base paint (A) in a solid tone or a metallic tone, and the coating film may be colored transparent or colored opaque.

Examples of the coloring pigment (A-3) include titanium dioxide, zinc white, carbon black, red iron,
Cadmium red, molybdenum red, graphite, cadmium yellow, chrome ero, titanium yellow, chromium oxide, cobalt green, ultramarine, navy blue, cobalt blue,
Solids selected from inorganic and organic pigments such as Prussian blue, cobalt blue, cobalt violet, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, dioxazine pigments, sulene pigments, perylene pigments, and thioindigo pigments Color pigments: flaky aluminum, mica, mica coated with metal oxide, mica-like iron oxide, silver-plated glass flake, titanium-coated graphite, metal titanium flake,
Metallic pigments such as phthalocyanine flakes; and the like. Alone from these, or 2
More than one species can be used in combination. The blending amount of the coloring pigment (A-3) can be arbitrarily selected according to the target color tone (solid tone or metallic tone), and is not limited.

The colored base paint (A) in the present method is
It is obtained by mixing a neutralized product of the resin (A-1), the crosslinking agent (A-2) and the coloring pigment (A-3) in an organic solvent.

As the organic solvent, any of the known organic solvents for coatings can be used, for example, esters, ethers, alcohols, amides, ketones, aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatics. Examples thereof include hydrocarbon solvents, and one or more solvents selected from these solvents can be used.
In particular, among them, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether acetate,
Diethylene glycol monoethyl ether acetate, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether,
Diethylene glycol diethyl ether, diethylene glycol monobutyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, methyl alcohol, ethyl alcohol, allyl alcohol, n-propyl alcohol, isopropyl alcohol, tertiary butyl alcohol, ethylene glycol, 1,2-propylene It is preferable to use a hydrophilic organic solvent such as glycol, 1,3-butylene glycol, 2,3-butylene glycol, hexylene glycol, hexanediol, dipropylene glycol, acetone, and acetone alcohol. One or two or more of these hydrophilic organic solvents can be used. The hydrophilic organic solvent is easily dissolved in water, and is an organic solvent that dissolves at 50 ° C. or more at 100 ° C. at 20 ° C., for example. The proportion of the hydrophilic organic solvent is suitably 20% by weight or more, especially 40 to 100% by weight, based on the total weight of the organic solvent contained in the colored base coating material (A) at the time of coating.

In the colored base paint (A), a part of these organic solvents is replaced by water such as deionized water to form a mixed system of an organic solvent and water, and a paint obtained by mixing each of the above components is also used. included. In a mixed system of an organic solvent and water, the organic solvent content is 50 to 100% by weight, and the water content is 0 to 5%.
A range of 0% by weight is suitable.

The colored base coating material (A) may further contain, if necessary, an antisettling agent, an extender and the like. The non-volatile content of the colored base paint (A) at the time of coating is usually 20 to 65% by weight. However, the amount of the organic solvent is reduced to prevent air pollution and save resources.
It is preferably a high solid type adjusted to 60 to 60% by weight, particularly 40 to 60% by weight.

The single coating film of the colored base coating material (A) is a colored opaque or colored transparent solid or metallic coating film. Here, an opaque coating film means a light transmittance of less than 5% in a cured film of 20μ, and a transparent coating film means a light transmittance of 5% or more in a cured film of 20μ.

In the present method, the colored base paint (A)
Can be applied directly to the object to be coated, such as an automobile outer panel (made of metal or plastic), but it is hardened by applying a primer such as a cationic or anionic electrodeposition paint and an intermediate paint. It is preferable to paint the surface.

The color base paint (A) is applied by adjusting the viscosity at the time of application to 13 to 60 seconds / Ford cup # 4/20 ° C., preferably 15 to 40 seconds / Ford cup # 4/20 ° C. , Airless spray, electrostatic coating, etc., the film thickness based on the cured coating film is 5 to 25 μm, especially 1
It is preferable to apply the coating so as to have a thickness of 0 to 20 μm. The coating film of the colored base paint (A) is left at room temperature for 1 to 20 minutes as needed without heating and curing, and then a thermosetting water-based coloring paint (B) is applied to the uncured coating surface. I do.

Water-based colored paint (B): A water-based liquid paint applied to the uncured coating surface of the colored base paint (A). The base resin (B-1), the crosslinking agent (B-2) and the color pigment (B) -3) is mixed and dispersed in water.

As the base resin (B-1), for example, an acrylic resin having a carboxyl group and a hydroxyl group,
Examples include vinyl resin and polyester resin.

The carboxyl group makes the resin easy to dissolve or disperse in water.
0 mgKOH / g, especially 30-100 mgKOH / g, is suitable. The hydroxyl group imparts crosslinking reactivity with the crosslinking agent (B-2), and its content is 1 based on the hydroxyl value.
0-150 mgKOH / g, especially 30-80 mgKOH
/ G is preferred. Among these base resins, the acrylic resin and the vinyl resin have a number average molecular weight of about 3,000 to 1
00,000, especially about 5,000 to 50,000, and polyester resin about 500 to 50,000, especially about 3,
000 to 30,000 are preferred.

The acrylic resin, vinyl resin and polyester resin (base resin B-1) are made of the above-mentioned colored base.
It is obtained by solution polymerization in an organic solvent using the components described for the hydroxyl group-containing resin (A-1) of the paint (A) so that the hydroxyl value, acid value and molecular weight fall within the above ranges. It can also be produced by emulsion polymerization in the presence of an aqueous dispersion stabilizer solution.

Examples of the dispersion stabilizer used in the emulsion polymerization include a nonionic surfactant and an anionic surfactant, and an acid value of 20 to 150 and a number average molecular weight of 5,000 to 5,000.
An aqueous solution of an aqueous resin such as 30,000 acrylic resin can be suitably used.

The emulsion polymerization itself can be carried out by a known method. Among them, an emulsion produced by a multi-stage polymerization method using a carboxyl group-containing unsaturated monomer is preferable because of excellent workability in coating. That is, first, polymerization is carried out in a system containing no or almost no carboxyl group-containing unsaturated monomer (usually 3% by weight or less in all monomers), and then a large amount of carboxyl group-containing unsaturated monomer (usually (5 to 30% by weight in the monomer), and polymerization and neutralization are preferable, because the viscosity of the emulsion increases, and there is no sagging or unevenness and the coating workability is excellent. As the neutralizing agent, the substances exemplified for the resin (A-1) can be used, and the amount of the neutralizing agent to be used is 0.1 to 2.0 equivalents, particularly 0.3 to 1.0 equivalent to the carboxyl group in the polymer. Two equivalents are suitable.

Further, as the base resin (B-1), polyisocyanate, polyetherpolyol or polyesterpolyol having a number average molecular weight of 500 to 5,000, low molecular weight polyol having a molecular weight of less than 500 and dimethylol are used. Polyurethanes obtained by urethane reaction of rualkanoic acid or the like can also be used.

The cross-linking agent (B-2) is used as the base resin (B-1)
And a three-dimensionally cross-linking reaction with the hydroxyl group to form a cured coating film of the aqueous coloring paint (B). One or more selected from block polyisocyanates and amino resins can be used. These block polyisocyanates and amino resins include a crosslinking agent (A)
One or more selected from those exemplified in -2) can be used.

The ratio of the base resin (B-1) to the crosslinking agent (B-2) was 5% based on the total weight of the two components.
0-90%, especially 65-80%, crosslinker 50-50
%, Particularly preferably 35 to 20%.

The coloring pigment (B-3) is an aqueous coloring paint (B).
This is for coloring the coating film in a solid tone or a metallic tone, and the coating film may be colored transparent or colored opaque. As the color pigment (B-3), a single pigment selected from the solid color pigments and the metallic pigments exemplified as the color pigments (A-3) of the color base paint (A), or a combination of two or more thereof. can do.

The water-based coloring paint (B) is a base resin (B-
1), a cross-linking agent (B-2) and a color pigment (B-3) are mixed and dispersed in water. In the water-based colored paint (B), a part of water can be replaced with the hydrophilic organic solvent exemplified in the colored base paint (A), and the content of the organic solvent is from 0 to 0 based on the total amount of water. 50% by weight is suitable.

The water-based coloring paint (B) may further contain, if necessary, an antisettling agent, an extender pigment and the like. The non-volatile content of the water-based colored coating (B) when applied is usually preferably 15 to 65% by weight, and the single coating is an opaque or transparent solid or metallic coating. Here, the opaque coating film means a light transmittance of less than 5% in a cured film of 20μ, and the transparent coating film has a light transmittance of 5% in a cured film of 20μ.
That is all.

The water-based colored paint (B) may be left uncured for 1 to 20 minutes at room temperature if necessary.
Paint on the painted surface. The viscosity at the time of application of the aqueous coloring paint (B) was adjusted to 15 to 60 seconds / Ford cup # 4/20 ° C, preferably 20 to 50 seconds / Ford cup # 4/20 ° C, and air spray, airless spray, electrostatic The thickness of the cured coating film is 5 to 40 μm, especially 10
It is preferable to apply the coating so as to have a thickness of up to 35 μm.

In the present method, the water-based colored paint (B) is applied to the uncured coated surface of the colored base paint (A), and then the thermosetting clear paint (C) is applied. Prior to coating, it is preferable that a two-layer coating film composed of the colored base paint (A) and the water-based colored paint (B) is preliminarily dried at 50 to 100 ° C. Most or all of the volatile components such as organic solvent and water in the two coatings are evaporated by the preliminary drying, but little or no cross-linking reaction of the coatings is performed. The gel fraction of the membrane is usually 0-5%. When the preliminary drying is performed, the coating film is volatilized and the coating film is dried and solidified. Therefore, the clear coating (C) is applied to the coated surface, and the solvent and the low molecular weight resin component contained in the coating film penetrate and diffuse into both the coating films. However, the occurrence of unevenness and the like can be prevented without reducing the viscosity of the two coating films and without reflowing the metallic pigment and the like.

Thermosetting organic solvent-based clear coating (C):
The thermosetting organic solvent-based clear paint (C) is an organic solvent-based thermosetting paint that forms a transparent coating film and is applied to the coating surface of the thermosetting water-based coloring coating material (B) and has a carboxyl group. Resin (C-1), a vinyl polymer (C-2) having an epoxy group, a hydroxyl group and a hydrolyzable alkoxysilyl group in one molecule, a reactive organopolysiloxane (C-
3) and a liquid paint having a solid content of 65 to 90% by weight, preferably 65 to 80% by weight, obtained by dissolving or dispersing the crosslinked fine particle polymer (C-4) in an organic solvent.

Resin having carboxyl group (C-1):
Usually, the acid value is 50 to 500 mgKOH / g, preferably 80 to 500 mgKOH / g.
It is 300 mgKOH / g. When the acid value of the resin (C-1) is less than 50 mgKOH / g, the curability of the obtained clear coating material (C) tends to decrease, and the acid resistance and scratch resistance of the coating film tend to decrease. If the value is more than 500 mgKOH / g, the compatibility with the polymer (C-2) and the reactive organopolysiloxane (C-3) tends to decrease, and the storage stability tends to be impaired. . The following are mentioned as resin (C-1).

(C-1-1) An acid anhydride group is contained in one molecule.
Vinyl polymer having a group obtained by esterification : Here, a group obtained by half-esterifying an acid anhydride group means a group obtained by adding an aliphatic monoalcohol to an acid anhydride group to open a ring (that is, by half-esterification). A) a group comprising a carboxyl group and a carboxylic ester group obtained. Hereinafter, this group may be simply referred to as a half ester group.

The resin (C-1-1) can be easily obtained by copolymerizing a vinyl monomer having a half ester group and other vinyl monomers by an ordinary method. Further, it can also be easily obtained by similarly copolymerizing a vinyl monomer having an acid anhydride group instead of the vinyl monomer having a half ester group, and then half-esterifying the acid anhydride group.

Examples of the vinyl monomer having an acid anhydride group include those having maleic anhydride, itaconic anhydride and the like. Examples of the vinyl monomer having a half ester group include those obtained by half esterifying the acid anhydride group of the vinyl monomer having the acid anhydride group.

As described above, the half esterification may be performed either before or after the copolymerization reaction. As the aliphatic monoalcohol used for the half esterification, low molecular weight monoalcohols, for example, methanol, ethanol,
Isopropanol, tert-butanol, isobutanol, methyl cellosolve, ethyl cellosolve and the like. The half-esterification reaction can be carried out according to a usual method, usually at a temperature from room temperature to about 80 ° C., using a tertiary amine as a catalyst if necessary.

Other vinyl monomers include, for example, vinyl monomers having a hydroxyl group; (meth) acrylates; vinyl ethers and aryl ethers;
Olefinic compounds and diene compounds; hydrocarbon ring-containing unsaturated monomers; nitrogen-containing unsaturated monomers, and the like.

As the vinyl monomer having a hydroxyl group,
For example, 2-hydroxyethyl (meth) acrylate,
C2-C8 hydroxyalkyl esters of acrylic acid or methacrylic acid such as 3-hydroxypropyl (meth) acrylate and hydroxybutyl (meth) acrylate; and polyether polyols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; A) Monoesters with unsaturated carboxylic acids such as acrylic acid; monoethers with polyether polyols such as polyethylene glycol, polypropylene glycol and polybutylene glycol and hydroxyl-containing unsaturated monomers such as 2-hydroxyethyl (meth) acrylate; Monoesterified product of an unsaturated compound containing an acid anhydride group such as maleic acid or itaconic anhydride and a glycol such as ethylene glycol, 1,6-hexanediol, neopentyl glycol, etc. Is a diester product; hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether; allyl alcohol and the like; 2-hydroxypropyl (meth) acrylate; α, β-unsaturated carboxylic acid and Cardura E10 (manufactured by Shell Petrochemical Co., Ltd.) Adducts with monoepoxy compounds such as (name) and α-olefin epoxides; adducts of glycidyl (meth) acrylate with monobasic acids such as acetic acid, propionic acid, p-tert-butylbenzoic acid and fatty acids; Adducts of the above hydroxyl group-containing monomer with lactones (eg, ε-caprolactone, γ-valerolactone) and the like can be mentioned.

Examples of (meth) acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, hexyl acrylate 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, stearyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n methacrylate -Butyl, isobutyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate,
C1-24 alkyl or cycloalkyl esters of acrylic acid or methacrylic acid such as stearyl methacrylate and cyclohexyl methacrylate; methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl acrylate, methoxyethyl methacrylate,
Examples thereof include alkoxyalkyl esters of acrylic acid or methacrylic acid having 2 to 18 carbon atoms, such as ethoxybutyl acrylate and ethoxybutyl methacrylate.

Examples of the vinyl ethers and aryl ethers include chain alkyl vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, butyl vinyl ether, tert-butyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether and octyl vinyl ether; cyclopentyl vinyl ether; Cycloalkyl vinyl ethers such as cyclohexyl vinyl ether; aryl vinyl ethers such as phenyl vinyl ether and trivinyl ether; aralkyl vinyl ethers such as benzyl vinyl ether and phenethyl vinyl ether; allyl ethers such as allyl glycidyl ether and allyl ethyl ether.

Examples of the olefinic compound and the diene compound include ethylene, propylene, butylene, vinyl chloride, butadiene, isoprene, chloroprene and the like.

Examples of the unsaturated monomer having a hydrocarbon ring include styrene, α-methylstyrene, phenyl (meth) acrylate, phenylethyl (meth) acrylate, phenylpropyl (meth) acrylate, benzyl (meth) acrylate, Phenoxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-
Acryloyloxyethyl hydrogen phthalate, 2
-Acryloyloxypropyl hydrogen phthalate, 2-acryloyloxypropyl hexahydrohydrogen phthalate, 2-acryloyloxypropyl tetrahydrohydrogen phthalate, esterified product of p-tert-butyl-benzoic acid and hydroxyethyl (meth) acrylate, dicyclopentenyl (Meth) acrylate and the like.

Examples of the nitrogen-containing unsaturated monomer include, for example,
N, N-dimethylaminoethyl (meth) acrylate,
N, N-diethylaminoethyl (meth) acrylate,
Nitrogen-containing alkyl (meth) acrylates such as Nt-butylaminoethyl (meth) acrylate; acrylamodo, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) Polymerizable amides such as acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide; 2-vinylpyridine, 1-vinyl-2-pyrrolidone, 4-vinylpyridine and the like Aromatic nitrogen-containing monomers; polymerizable nitriles such as acrylonitrile and methacrylonitrile; allylamine.

As a copolymerization method, a general polymerization method of a vinyl monomer can be used, but a solution type radical polymerization method in an organic solvent is most suitable in consideration of versatility and cost. That is, aromatic solvents such as xylene and toluene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ester solvents such as ethyl acetate, butyl acetate, isobutyl acetate and 3-methoxybutyl acetate; n-butanol and isopropyl alcohol By performing a copolymerization reaction in the range of about 60 to 150 ° C. in the presence of a polymerization initiator such as azobisisobutyronitrile and benzoyl peroxide in a solvent such as an alcohol solvent, the desired polymer can be easily obtained. Can be obtained.

The copolymerization amount of each of the vinyl monomer having a half ester group or an acid anhydride group and the other vinyl monomer is usually appropriate to be as follows in all the monomers. That is, from the viewpoint of curability and storage stability, the vinyl monomer having a half ester group or an acid anhydride group is about 5 to 40% by weight, preferably 10 to 30% by weight.
% By weight. It is appropriate that the other vinyl monomer accounts for about 60 to 95% by weight, preferably 70 to 90% by weight. The amount of styrene used among the other vinyl monomers is suitably up to about 20% by weight from the viewpoint of the weather resistance of the cured coating film. still,
When a vinyl monomer having an acid anhydride group is used, half esterification after polymerization is as described above.

The resin (C-1-1) is preferably an acrylic polymer having a number average molecular weight of 2,000 to 10,000. If the number average molecular weight is less than 2,000, the weather resistance of the cured coating film tends to decrease,
If it exceeds 000, the compatibility with the polymer (B) and the reactive organopolysiloxane (C) tends to decrease, and neither is preferable.

(C-1-2) Carboxyl Group-Containing Polyester
Steal polymer: Resin (C-1-2) is a carboxyl group-containing polyester polymer.

The number average molecular weight of the carboxyl group-containing polyester polymer to be used is not particularly limited, but it is usually appropriate to be about 1,500 to 2,000.

The carboxyl group-containing polyester polymer includes ethylene glycol, butylene glycol, 1,6
-Can be easily obtained by a condensation reaction between a polyhydric alcohol such as hexanediol, trimethylolpropane, and pentaerythritol and a polycarboxylic acid such as adipic acid, terephthalic acid, isophthalic acid, phthalic anhydride, and hexahydrophthalic anhydride. it can. For example, a carboxyl group-containing polyester polymer can be obtained by a one-step reaction under the compounding condition of polycarboxylic acid with excess carboxyl group. After synthesizing the polyester polymer of the above, a carboxyl group-containing polyester polymer can also be obtained by post-adding an acid anhydride group-containing compound such as phthalic anhydride, hexahydrophthalic anhydride and succinic anhydride.

Further, the carboxyl group-containing polyester polymer has improved compatibility with the polymer (C-2) and the reactive organopolysiloxane (C-3),
In order to impart reactivity with the hydrolyzable alkoxysilyl group contained in 2), it is also effective to introduce a hydroxyl group within a hydroxyl value of 0 to 100 mgKOH / g. The introduction of a hydroxyl group can be carried out by stopping the condensation reaction halfway under a compounding condition of excess carboxyl group,
Conversely, under the compounding condition of excess hydroxyl group, the synthesis can be easily performed by synthesizing a polyester polymer having a hydroxyl group terminal and then compounding an acid anhydride group-containing compound to be added later in a smaller amount than the hydroxyl group.

(C-1-3) No polyol and 1,2-acid
Half ester generated by addition reaction with hydrate: Resin (C-1-3) is a half ester generated by reaction between polyol and 1,2-acid anhydride.

Although the number average molecular weight of the half ester is not particularly limited, it is usually a low molecular weight of about 400 to 1,000 and has a high reactivity with an epoxy group. Help form.

The half ester is composed of a polyol and 1,2-
It is obtained by reacting with an acid anhydride under conditions sufficient for a ring-opening reaction of the acid anhydride to occur and for substantially no polyesterification reaction to occur. Such reaction products have a low molecular weight and a narrow molecular weight distribution. They also exhibit a low volatile organic content in the composition and impart excellent properties in the resulting coating.

The half ester is composed of a polyol and 1,2-
The reaction is performed with an acid anhydride in an inert atmosphere such as a nitrogen atmosphere in the presence of a solvent. Examples of suitable solvents include ketones such as, for example, methyl amyl ketone, diisobutyl ketone, methyl isobutyl ketone; aromatic hydrocarbons such as toluene, xylene; or other organic solvents such as dimethylformamide and N-methylpyrrolidone. Is mentioned.

The reaction temperature is preferably low, ie 150 ° C.
Not more than 120 ° C., usually 70 to 15
0 ° C, preferably 90 to 120 ° C. If the temperature exceeds 150 ° C., a polyesterification reaction occurs, which is not desirable. If the temperature is lower than 70 ° C., a sufficient reaction rate cannot be obtained, which is not preferable.

The reaction time basically varies somewhat depending on the reaction temperature, but is usually about 10 minutes to 24 hours.

The equivalent ratio of acid anhydride: polyol is about 0.8: 1 to 1.2: 1, calculated on the assumption that the acid anhydride is monofunctional.
Within the range, the desired half ester can be obtained to the maximum.

The acid anhydride used for preparing the desired half ester has about 2 to 2 carbon atoms except for the carbon atom in the acid portion.
30. Examples of such include aliphatic, cycloaliphatic, olefinic and cyclic olefinic anhydrides and aromatic anhydrides. Substituted aliphatic and aromatic anhydrides are included in the aliphatic and aromatic anhydrides, so long as the substituents do not adversely affect the reactivity of the anhydride or the properties of the resulting half ester. . Examples of substituents include chloro, alkyl and alkoxy groups. Examples of acid anhydrides include succinic anhydride, methyl succinic anhydride, dodecenyl succinic anhydride, octadecenyl succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexa Hydrophthalic anhydride, alkylhexahydrophthalic anhydride (eg, methylhexahydrophthalic anhydride), tetrafluorophthalic anhydride, endomethylenetetrahydrophthalic anhydride, chlorendic anhydride, itaconic anhydride, citracone Acid anhydrides and maleic anhydride.

The polyols that can be used are those having about 2 to 20 carbon atoms.
It has. Preferably, diols, triols and mixtures thereof are used. Examples of such include polyols having 2 to 10 carbon atoms. Examples of suitable are aliphatic polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, glycerol,
2,3-butanetriol, 1,6-hexanediol, neopentyl glycol, diethylene glycol,
Dipropylene glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, trimethylolpropane, 2,2,4-trimethylpentane-1,3-diol, pentaerythritol and 1,
2,3,4-butanetetraol is exemplified. Aromatic polyols such as bisphenol A and bis (hydroxymethyl) xylene may be used.

An epoxy group, a hydroxyl group and a water content in one molecule
Vinyl polymer having a decomposable alkoxysilyl group (C-
2): The polymer (C-2) is a vinyl polymer having an epoxy group, a hydroxyl group and a hydrolyzable alkoxysilyl group in one molecule.

The polymer (C-2) is obtained by mixing a vinyl monomer having an epoxy group, a vinyl monomer having a hydroxyl group, a vinyl monomer having a hydrolyzable alkoxysilyl group and other vinyl monomers with the resin (C-1-1). ) Can be easily obtained by copolymerization in the same manner as in the case of (1).

Examples of the vinyl monomer having an epoxy group include glycidyl (meth) acrylate and allyl glycidyl ether. Examples of the vinyl monomer having a hydrolyzable alkoxysilyl group include vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, vinyltris (2-methoxyethoxy) silane, and γ- (meth) silane. Acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, vinyltriacetoxysilane, β- (meth) acryloyloxyethyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, γ- (Meth) acryloyloxypropylmethyldiethoxysilane and the like, and preferably, from the viewpoint of low-temperature curability and storage stability, vinyl acetate in which the hydrolyzable alkoxysilyl group is an ethoxysilyl group. Examples thereof include rutriethoxysilane, vinylmethyldiethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, and γ- (meth) acryloyloxypropylmethyldiethoxysilane. The vinyl monomer having a hydroxyl group and other vinyl monomers are the same as those described above.

The copolymerization amount of each of a vinyl monomer having an epoxy group, a vinyl monomer having a hydroxyl group, a vinyl monomer having a hydrolyzable alkoxysilyl group, and other vinyl monomers is usually as follows: The ratio is appropriate. That is, the amount of the vinyl monomer having an epoxy group is about 5 to 60% by weight, preferably 10 to 40% by weight, from the viewpoint of curability and storage stability. The vinyl monomer having a hydroxyl group is
From the viewpoint of curability and storage stability, about 3 to 50% by weight,
Preferably, it is 5 to 30% by weight. The amount of the vinyl monomer having a hydrolyzable alkoxysilyl group is about 3 to 40% by weight, preferably 5 to 20% by weight, from the viewpoint of curability and cost. Further, other vinyl monomers are about 10 to 80% by weight, preferably 20 to 80% by weight.
Suitably, it is 50% by weight. The amount of styrene used among the other vinyl monomers is suitably up to about 20% by weight from the viewpoint of the weather resistance of the cured coating film.

The polymer (C-2) obtained by polymerization in the above copolymerization amount usually has an epoxy group content of from 0.5 to 5.0 mmol / g, preferably from 0.8 to 5.0 mmol / g.
~ 2.5 mmol / g, hydroxyl value is 10 ~ 200mgKOH /
g, preferably 30 to 120 mg KOH / g, having a hydrolyzable alkoxysilyl group content of 0.3 to 5.0 mmol / g,
Preferably, it is 1.0 to 3.0 mmol / g.

When the epoxy group content of the polymer (C-2) is less than 0.5 mmol / g, the curability of the resulting composition is reduced, and the acid resistance and scratch resistance of the coating film are reduced. When the content of the epoxy group is more than 5.0 mmol / g, the compatibility with the resin (C-1) and the reactive organopolysiloxane (C-3) is reduced, and storage stability is impaired. Both tend to be undesirable.

The polymer (C-2) has a hydroxyl value of 10
If it is less than mgKOH / g, the curability of the resulting composition will decrease and the acid resistance and scratch resistance of the coating will tend to decrease, and if the hydroxyl value exceeds 200 mgKOH / g, the water resistance of the coating will increase. None of these is preferred because the properties tend to decrease.

When the content of the hydrolyzable alkoxysilyl group in the polymer (C-2) is less than 0.3 mmol / g, the curability of the obtained composition is lowered and the acid resistance of the coating film is reduced.
Abrasion resistance tends to decrease, and if the content of the hydrolyzable alkoxysilyl group is more than 5.0 mmol / g, the cost increases, and neither is preferred. Further, the polymer (C-2) has a number average molecular weight of 2,000 to 1
It is preferably an acrylic polymer in the range of 000. If the number average molecular weight is less than 2,000, the weather resistance of the cured coating film tends to decrease, and if it exceeds 10,000, the compatibility with the resin (C-1) and the reactive organopolysiloxane (C-3) Are liable to decrease, and thus both are not preferred.

Reactive organopolysiloxane (C-
3): The reactive organopolysiloxane (C-3) used in the clear coating (C) is a component used to impart high acid resistance and abrasion resistance to the coating film, and the resin (C)
As long as it is compatible with -1) and the polymer (C-2), it can be used without any particular limitation.

The reactive organopolysiloxane (C-
3) may have any of linear, branched, net-like, and cyclic structures, and as the organo group (organic group), an alkyl group (methyl group, ethyl group, propyl group, butyl group, Hexyl group), alkenyl group, aryl group, allyl group, phenyl group and the like. Among them, those having an organo group such as a methyl group, a vinyl group and a phenyl group are practically advantageous in that they are manufactured industrially and are inexpensive.

Examples of the reactive functional group include a silanol group, an alkoxysilyl group, an alcoholic hydroxyl group, a glycidyl group, an amino group, a mercapto group, a carboxyl group, an amide group, a vinyl group, and a (meth) acryloxy group. Among them, an alkoxysilyl group, an alcoholic hydroxyl group and a glycidyl group are preferred.

The number of the reactive functional groups is preferably one or more in one molecule of the reactive organopolysiloxane (C-3).

Regarding the molecular weight of the component (C-3), (C-3)
Although it can be appropriately selected within a range having compatibility with the component -1) and the component (C-2) and cannot be unconditionally described, the compatibility tends to decrease as the molecular weight increases.

The number of silicon atoms contained in one molecule is preferably from 2 to 300,
100 are more preferable, and 3 to 50 are particularly preferable.

The component (C-3) is known, and specific examples thereof include those disclosed in JP-A-5-43696 and JP-A-7-70509. As the component (C-3), only one type may be used alone, or two or more types may be used in combination.

The crosslinked fine particle polymer (C-4) used for the clear coating material (C) includes the resin (C-1) having a carboxyl group and an epoxy group, a hydroxyl group and a hydrolyzate in one molecule, respectively. No miscibility with a system comprising a vinyl polymer (C-2) having a reactive alkoxysilyl group and a reactive organopolysiloxane (C-3);
In addition, the term refers to polymers that can be stably dispersed, and the purpose is to constitute a paint (C-
It is to add so-called pseudoplastic viscosity behavior to each of the mixtures consisting of 1), (C-2) and (C-3).

All of the above-mentioned mixtures have substantially Newtonian flow properties, have no yield value due to their relatively low molecular weight, or have very small values, so Various coating defects appear, such as when performing coating work with the material vertical, or when sagging etc. is likely to occur due to temperature rise at the time of baking performed after such painting, or repelling is likely to occur .

However, for the above mixture,
When a crosslinked fine particle polymer is added as described below, the apparent viscosity at the time of standing increases, but when high shear stress is applied, such as during spraying, it is sufficient. The viscosity is reduced and the spraying operation can be performed without any additional difficulty, and after a few seconds or a few minutes after the application to the base material, The effect of preventing such coating film defects and the like can be sufficiently exerted such that structural viscosity is exhibited and coating film defects such as repelling do not occur.

As the crosslinked fine particle polymer (C-4),
Naturally, it is desirable that the composition of the cured coating film after baking be completely transparent.

As a specific example of the crosslinked fine particle polymer (C-4), an aqueous emulsion or a fine particle polymer having a known intramolecular crosslinked structure obtained by an aqueous suspension polymerization method or a non-aqueous dispersion polymerization method can be used. It is. Among them, the aqueous emulsion or the fine particle polymer having an intramolecular cross-linked structure obtained by the aqueous suspension polymerization method is prepared by physical or chemical means such as evaporation or azeotropic distillation of water or precipitation or aggregation of the polymer (particles). , Can be separated in the form of a solid, or when subjected to such physical or chemical means, resins and / or organic solvents other than the various polymers in the respective paints In the presence of, the medium of the desired crosslinked fine particle polymers,
It is also possible to directly replace water with the resins and / or organic solvents.

In the present invention, as the crosslinked fine particle polymer, a polymerizable monomer having at least two radically polymerizable unsaturated groups in a molecule as disclosed in JP-A-3-66770 and Crosslinked fine particle polymers obtained by emulsion polymerization of other radically polymerizable unsaturated monomers in the presence of a reactive emulsifier containing an allyl group in the molecule, and those disclosed in JP-A-1-95116. A polymer containing an alkoxysilyl group-containing vinyl monomer as an essential monomer component is used as a dispersion stabilizer resin, and a polymer obtained by polymerizing a radical polymerizable unsaturated monomer in an organic liquid in the presence of the resin. A non-aqueous dispersion of a particulate polymer insoluble in an organic liquid is preferably used.

Such a crosslinked fine particle polymer is substantially non-swellable and non-fusible even in a solvent having a high polymer dissolving power such as toluene or ethyl acetate. When added to a resin solution or dispersion (binder resin) containing a solvent having such a high dissolving power, the resin (solution) dispersion has a high resin content, that is, a high solid, without increasing the viscosity of the resin (solution) dispersion. A fine particle polymer having a high cross-linking density that can realize the yield of the dispersion and that, after drying, can form a solid resin composition together with the added resin solution or dispersion. Can be defined as

Resin having a carboxyl group which is an essential component in the clear coating composition (C) (C-1), a vinyl polymer having an epoxy group, a hydroxyl group and a hydrolyzable alkoxysilyl group in one molecule (C-2) , Reactive organopolysiloxane (C-3) and crosslinked fine particle polymer (C-
The compounding ratio of 4) is such that the resin (C-1) and the polymer (C-2)
And the ratio of the reactive organopolysiloxane (C-3) to the equivalent ratio of the former carboxyl group to the latter epoxy group is 1: 0.5 to 0.5: 1. The mixing ratio of the polysiloxane (C-3) is 3 to 50 parts by weight based on 100 parts by weight of the total amount of the resin (C-1) and the polymer (C-2), and the crosslinked fine particle polymer (C- 4) The compounding ratio of the resin (C-1) and the polymer (C-
The ratio is preferably 1 to 20 parts by weight based on 100 parts by weight of the total of 2) and the reactive organopolysiloxane (C-3). If the mixing ratio is outside the above range, the curability tends to decrease, and the acid resistance and scratch resistance of the coating film tend to decrease. A more preferable mixing ratio is such that the mixing ratio of the resin (C-1), the polymer (C-2) and the reactive organopolysiloxane (C-3) is equivalent to the former carboxyl group and the latter epoxy group. 1: 0.6-
0.6: 1, and the mixing ratio of the reactive organopolysiloxane (C-3) is 5 with respect to 100 parts by weight of the total amount of the resin (C-1) and the polymer (C-2). To 30 parts by weight, and the blending ratio of the crosslinked fine particle polymer (C-4) is 100 in total of the resin (C-1), the polymer (C-2) and the reactive organopolysiloxane (C-3). The ratio is 1 to 10 parts by weight with respect to parts by weight.

In the clear coating (C), if necessary,
A curing catalyst can be included. As a curing catalyst that can be used, a catalyst effective for a crosslinking reaction between a carboxyl group and an epoxy group includes tetraethylammonium bromide, tetrabutylammonium bromide, tetraethylammonium chloride, tetrabutylphosphonium bromide, triphenylbenzylphosphonium chloride, and the like. Quaternary salt catalysts; and amines such as triethylamine and tributylamine. Of these, quaternary salt catalysts are preferred. Furthermore, a compound obtained by blending a phosphate compound such as dibutyl phosphoric acid with an equivalent amount of the quaternary salt to the quaternary salt can improve the storage stability of the paint without impairing the curability and reduce the electric resistance value of the paint. (I.e., a decrease in spray coating suitability) is preferred. Examples of the catalyst effective for the crosslinking reaction of the ethoxysilyl group include tin catalysts such as dibutyltin dilaurate and dibutyltin diacetate; titanium catalysts such as tetrabutyl titanate; and amines such as triethylamine and tributylamine. .

The above two curing catalysts can be used alone or in combination. However, it is desirable to use them together from the viewpoint of curability and scratch resistance.

Further, a so-called dehydrating agent such as trimethyl orthoacetate can be used in the clear coating material (C), if necessary, in order to suppress the deterioration of the coating material due to the compounding solvent and moisture present in the air. is there.

In the clear coating (C), if necessary,
Known general pigments such as color pigments, extender pigments, and rust-preventive pigments can be blended.

Examples of the coloring pigments include quinacridone-based pigments such as quinacridone red, azo-based pigments such as pigment red, phthalocyanine blue, phthalocyanine lines, and the like.
Organic pigments such as phthalocyanine based pigments such as perylene red; inorganic pigments such as titanium oxide and carbon black; aluminum flakes, nickel flakes, copper flakes, brass flakes, chrome flakes, and parmica And metallic pigments such as colored parmica.

If necessary, various resins such as polyester resin, alkyd resin, silicone resin and fluororesin, and non-aqueous polymer particles can be added to the clear coating material (C). Also, for example, melamine resin,
It is also possible to use a small amount of a crosslinking agent such as a blocked isocyanate. Furthermore, if necessary, general paint additives such as an ultraviolet absorber, an antioxidant, a surface conditioner, and a defoaming agent can be blended.

The clear coating (C) is usually used as an organic solvent type coating composition. As the solvent, various organic solvents for coatings, for example, aromatic or aliphatic hydrocarbon solvents; alcohol solvents; ester solvents; ketone solvents; ether solvents can be used. As the organic solvent to be used, the one used at the time of preparing the polymer to be blended may be used as it is, or may be added as appropriate. The clear coating (C) contains the above-mentioned components as main components, but if necessary, a coloring pigment, a metallic pigment, an interference pattern pigment such as mica, and the like can be added to such an extent that the transparency of the coating film is not hindered.

In the present method, the colored base paint (A) and the water-based colored paint (B) are applied, and then the
After preliminarily drying at 100 ° C. for 5 to 60 minutes, a clear paint (C) having a viscosity at the time of application of 15 to 50 seconds, preferably 20 to 40 seconds, is applied to the coated surface of the water-based colored paint (B).
By air spray, airless spray, electrostatic coating, etc., the film thickness based on the cured coating film is 20 to 60 μm, especially 3
Coat so as to have a thickness of 0 to 50 μm. Then, if necessary, the mixture is left at room temperature for 1 to 20 minutes, and then heated at 120 to 180 ° C. for 10 to 60 minutes to form a three-color paint comprising a colored base paint (A), an aqueous colored paint (B) and a clear paint (C). The coating film forming method of the present invention is achieved by simultaneously three-dimensionally curing the layer coating film.

In the present method, the colored base paint (A),
There are various specific examples of the form of the three-layer coating film structure using the water-based coloring paint (B) and the clear paint (C), and typical examples thereof are as follows.

1) Opaque solid color coating (A) / opaque metallic coating (B) / clear coating (C) 2) Opaque solid color coating (A) / transparent metallic coating (B) / clear Coating (C) 3) Opaque solid color coating (A) / opaque solid color coating (B) / clear coating (C) 4) Opaque solid color coating (A) / transparent solid color coating Film (B) / clear coating (C) 5) Transparent solid color coating (A) / opaque metallic coating (B) / clear coating (C) 6) Transparent solid color coating (A) / transparent Metallic coating (B) / clear coating (C) 7) Transparent solid color coating (A) / opaque solid color coating (B) / clear coating (C) 8) Transparent solid color coating ( A) / Transparent solid color coating film (B) / Clear coating film (C) 9) Opaque metallic coating (A) / opaque metallic coating (B) / clear coating (C) 10) Opaque metallic coating (A) / transparent metallic coating (B) / clear coating (C) 11) Opaque metallic coating (A) / opaque solid color coating (B) / clear coating (C) 12) Opaque metallic coating (A) / transparent solid color coating (B) / clear coating (C) 13) Transparent metallic coating (A) / opaque metallic coating (B) / clear coating (C) 14) Transparent metallic coating (A) / transparent metallic coating (B) / clear coating (C) 15) Transparent metallic coating (A) / opaque solid color coating (B) / clear coating (C) 16) Transparent metallic coating (A) / transparent solid color
Coating (B) / Clear coating (C) The technical effects achieved by the method of the present invention are as follows.

[0117] 1. Organic solvent-based colored base paint (A) containing a neutralized product of a hydroxyl group-containing resin having an acid value of 5 to 100
The neutralized product in the uncured coating film has strong water absorption. Therefore, when the water-based colored paint (B) is applied to the uncured coated surface, the water content in the paint (B) coating film is rapidly absorbed,
The viscosity was increased, and generation of sagging and metallic unevenness of the coating film could be prevented. Therefore, the finished appearance is excellent irrespective of the surrounding humidity at the time of applying the water-based coloring paint (B).

[0118] 2. When the colored base paint (A) and the water-based colored paint (B) are applied and preliminarily dried at 50 to 100 ° C., and then the clear paint (C) is applied, a mixed layer of the water-based colored paint and the clear paint does not occur. The occurrence of sidearms and sagging was prevented.

3. Since the water-based coloring paint (B) is a water-based paint, the metallic pigment is easily oriented in parallel to the coating surface as compared with the organic solvent-based paint, and the pearly luster is improved.

[0120] 4. Since the water-based coloring paint (B) is applied to the uncured coating surface of the organic solvent-based coloring base paint (A),
Even if the humidity at the time of painting fluctuates, the paint hardly flows or the surface of the paint becomes rough, so that it is no longer necessary to strictly control the humidity at the time of painting.

5. The resulting coating has improved acid resistance and abrasion resistance.

[0122]

EXAMPLES Examples and comparative examples according to the present invention will be described below. All parts and percentages are based on weight.

1. Production Example 1) Acrylic resin solution (a-1) Monomer component-1 (Note 1) was added to 60 parts of butyl cellosolve heated to 120 ° C. over 3 hours and copolymerized.
Acid value 40, hydroxyl value 52 and number average molecular weight about 10.0
Acrylic resin solution (a-
1) was obtained.

Note 1: Monomer component-1 30 parts of methyl methacrylate, 23 parts of ethyl acrylate,
It consists of 30 parts of butyl acrylate, 12 parts of hydroxyethyl methacrylate, 5 parts of acrylic acid and 2 parts of α, α′-azobisisobutyronitrile.

2) Acrylic resin solution (a-1N) To 100 parts of acrylic resin solution (a-1) was added 3.5 parts of dimethylaminoethanol for neutralization. A resin solution (a-1N) was obtained.

3) Polyester resin solution (b-1) 0.7 mol of neopentyl glycol, 0.3 mol of trimethylolpropane, 0.4 mol of phthalic anhydride and 0.5 mol of adipic acid were placed in a reaction vessel. ~ 230 ° C
For 5 hours, then trimellitic anhydride 0.03
After the addition by mol and further reacting at 180 ° C. for 1 hour, butyrocellosolve was added thereto to obtain a polyester resin solution (b- 1) was obtained.

4) Polyester resin solution (b-1N) 100 parts of the polyester resin solution (b-1) was neutralized by adding 4 parts of dimethylaminoethanol, and then isopropyl alcohol was added to obtain a polyester resin solution having a nonvolatile content of 60%. (B-1N) was obtained.

5) Acrylic resin emulsion (c-1) 140 parts of deionized water and 30% "Newco
l707SF "(surfactant, manufactured by Nippon Emulsifier Co., Ltd.
2.5 parts of trade name) and 1 part of the following monomer component-2 (Note 2) are added, mixed in a nitrogen stream, and 3 parts of a 3% ammonium persulfate aqueous solution is added at 60 ° C. Then, after heating to 80 ° C., 79 parts of monomer component-2 (Note 2), 30% “N
ewcol 707SF "2.5 parts, a monomer emulsion comprising 4 parts of a 3% aqueous solution of ammonium persulfate and 42 parts of deionized water were added to the reaction vessel over 4 hours using a metering pump. After completion of the addition, it is aged for 1 hour.

Further, at 80 ° C., the following monomer components:
3 (Note 3) 20.5 parts and 4 parts of a 3% aqueous solution of ammonium persulfate are simultaneously dropped in parallel into the reaction vessel in 1.5 hours. Thereafter, the mixture was aged for 1 hour, diluted with 30 parts of deionized water, and filtered at 30 ° C. with a 200 mesh nylon cloth. Deionized water was further added to the filtrate, and the pH was adjusted to 7.5 with dimethylaminoethanolamine to obtain an acrylic resin emulsion (c-1) having an average particle diameter of 0.1 μm and a nonvolatile content of 20%.

Note 2: Monomer component-2 55 parts of methyl methacrylate, 8 parts of styrene, 9 parts of n-butyl acrylate, 2-hydroxyethyl acrylate 5
Parts, 2 parts of 1,6-hexanediol diacrylate and 1 part of methacrylic acid.

Note 3: Monomer component-3 5 parts of methyl methacrylate, 7 parts of n-butyl acrylate,
It consists of 5 parts of 2-ethylhexyl acrylate, 3 parts of methacrylic acid and 0.5 part of 30% “Newcol 707SF”.

6) Half ester formed by addition reaction between polyol and 1,2-acid anhydride (e-1) A 3-methyl glass flask equipped with a stirrer, a thermometer and a condenser was charged with 3-methyl 236 parts of -1,5-pentanediol, 134 parts of trimethylolpropane, 1078 parts of hexahydrophthalic anhydride and 780 parts of xylene were charged and heated to 120 ° C. in a nitrogen atmosphere to cause a reaction. The reaction mixture was kept at this temperature for 4 hours and then cooled,
Solid content 65%, Gardner viscosity (25 ° C) R, acid value 27
A solution of 1 mg KOH / g of half ester (e-1) was obtained.

7) Vinyl polymer having epoxy group, hydroxyl group and hydrolyzable alkoxysilyl group (f-1) In a 5-liter glass flask equipped with a stirrer, a thermometer and a condenser, 410 parts of xylene and n-butanol 7
After charging 7 parts, the mixture was heated to 125 ° C. with an electric heating mantle, and at that temperature, a mixture of the following monomer compositions was evenly dropped over 4 hours. Incidentally, azobisisobutyronitrile is a polymerization initiator.

Glycidyl methacrylate 504 parts (35%) 4-hydroxy n-butyl acrylate 216 parts (15%) γ-methacryloxypropyltriethoxysilane 216 parts (15%) n-butyl acrylate 216 parts (15%) Styrene 288 parts (20%) azobisisobutyronitrile 72 parts Then, after aging for 30 minutes, further 90 parts of xylene,
A mixture of 40 parts of n-butanol and 14.4 parts of azobisisobutyronitrile was added dropwise over 2 hours.
After aging for a time, a solution of the acrylic polymer (f-1) having a final polymerization rate of 100% was obtained.

The polymer solid content of the obtained polymer liquid was 70%.
%, Gardner viscosity (25 ° C.) V. The number average molecular weight of this polymer was 2,000. The epoxy group content of this polymer was 2.12 mmol / g, the hydroxyl value was 78 mgKOH / g, and the ethoxysilyl group content was 1.55 mmol / g.

8) Crosslinked fine particle polymer (g-1) 1 equipped with a stirrer, thermometer, cooling pipe and heating mantle
In a liter flask, 3547.5 parts of deionized water and 5
20 parts of 0% “Latemul S-120A” (trade name, manufactured by Kao Corporation, trade name, sulfosuccinic allyl group-containing anionic reactive emulsifier) was charged, and the temperature was raised to 90 ° C. while stirring. In addition, “VA”, a water-soluble azoamide polymerization initiator,
-086 "(manufactured by Wako Pure Chemical Industries, Ltd., trade name: 2,2 '
-Azobis [2-methyl-N- (2-hydroxyethyl) -propionamide]) in deionized water 5
20% of the aqueous solution dissolved in 00 parts was added. After 15 minutes, 150 parts of styrene, 550 parts of methyl methacrylate, n
5% of a monomer mixture consisting of 150 parts of -butyl acrylate, 50 parts of 2-hydroxyethyl acrylate and 100 parts of 1,6-hexanediol diacrylate were added. Then, after further stirring for 30 minutes, the dropping of the remaining monomer mixture and polymerization initiator was started. The monomer mixture was added dropwise for 3 hours, and the polymerization initiator was added dropwise for 3.5 hours, during which the polymerization temperature was kept at 90 ° C. After completion of the dropwise addition of the polymerization initiator aqueous solution, the mixture was heated at 30 ° C. for 30 minutes, cooled to room temperature, and taken out using a filter cloth to obtain an aqueous dispersion of an aqueous crosslinked fine particle polymer having a solid content of 20%.

The aqueous dispersion was placed on a stainless steel vat for 60 minutes.
It dried in the electric hot air type dryer of ° C, and was taken out as a solid resin. Thereafter, xylene heated to 60 ° C / n-
Dispersed in a mixed solvent of butyl alcohol = 50/50 (weight ratio) to form a crosslinked fine particle polymer having a solid content concentration of 15% (g
-1) A dispersion was obtained.

The resulting dispersion had a Gardner viscosity (25
C) A2, the particle size of the polymer particles was 70 nm (measured with a Coulter Nanosizer N-4).

9) Acrylic resin solution (a-2) (for comparison) 40 parts of Swazole # 1000 (trade name, manufactured by Maruzen Oil Co., Ltd.) heated to 120 ° C. were mixed with monomer component-4 (Note 4). )
Was added for 3 hours and copolymerized to obtain an acrylic resin solution (a-2) having a hydroxyl value of 120 and a number average molecular weight of about 6,000 and a nonvolatile content of 70%.

Note 4: Monomer component-4 30 parts of styrene, 35 parts of butyl acrylate, 10 parts of 2-ethylhexyl methacrylate, 25 parts of 2-hydroxyethyl acrylate and α, α'-azobisisobutyronitrile Consists of four parts.

10) Non-aqueous dispersion of acrylic resin (d-1)
(Comparative) A solution consisting of 58 parts of 60% Uban 28-60 (trade name, melamine resin, manufactured by Mitsui Toatsu Chemicals, Inc.), 30 parts of n-heptane, and 0.15 part of benzoyl peroxide was charged into a reaction vessel. After heating to 95 ° C., the following monomer component-5 (Note 5) was added dropwise over 3 hours. One hour after the completion of the dropwise addition, a mixture of 0.65 parts of t-butyl peroctoate and 3.5 parts of Shellsol 140 was added dropwise over 1 hour, and then stirred at 95 ° C. for 2 hours. did. The solvent was removed under reduced pressure to obtain an acrylic resin non-aqueous dispersion (d-1) having a resin solid content of 60% and a varnish viscosity of A (Gardner bubble viscometer).

Note 5: Monomer component-5 15 parts of styrene, 9 parts of acrylonitrile, 13 parts of methyl methacrylate, 15 parts of methyl acrylate, 1.8 parts of n-butyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 1 part of acrylic acid .2 parts, 0.5 parts of benzoyl peroxide, 5 parts of n-butanol, 30 parts of Schelsol 140 and 9 parts of n-heptane.

11) Preparation of Colored Base Coating (A-1) 70 parts (solid content) of acrylic resin solution (a-1N), Cymel 370 (trade name, manufactured by Mitsui Cytec Co., Ltd., melamine resin, solid content 88%) ) 30 parts (solid content), 99.98 parts of titanium dioxide pigment and 0.02 carbon black
Was mixed with isopropanol and dispersed uniformly. Non-volatile content 40%, viscosity 25 seconds / Ford cup # 4/20
° C and the color tone of the coating film was Munsell chart N8.5.

12) Preparation of Colored Base Coating (A-2) 70 parts (solid content) of a polyester resin solution (b-1N)
30 parts of Cymel 370 (solid content), titanium dioxide 9
9.98 parts and 0.02 parts of carbon black were mixed with isopropanol and uniformly dispersed. Nonvolatile content 5
0%, viscosity 25 seconds / Ford cup # 4/20 ° C., and the coating color tone was Munsell chart N8.5.

13) Preparation of Colored Base Coating (A-3) 35 parts (solid content) of an acrylic resin solution (a-1N), 35 parts (solid content) of a polyester resin solution (b-1N), 3030 parts of Cymel 370 ( Solid content), titanium dioxide pigment 9
9.98 parts and 0.02 parts of carbon black were mixed with isopropanol and uniformly dispersed. Nonvolatile content 4
3%, viscosity 25 seconds / Ford cup # 4/20 ° C., and the coating color tone was Munsell chart N8.5.

14) Preparation of colored base paint (A-4) (for comparison) 70 parts (solid content) of acrylic resin solution (a-1), 30 parts (solid content) of Cymel 370, titanium dioxide pigment
98 parts and 0.02 parts of carbon black were mixed with isopropanol and uniformly dispersed. Nonvolatile 40
%, Viscosity 25 seconds / Ford cup # 4/20 ° C., and the coating color tone was Munsell chart N8.5. 15) Preparation of colored base paint (A-5) (for comparison) 70 parts (solid content) of polyester resin solution (b-1), 3030 parts (solid content) of Cymel 370, titanium dioxide 99.
98 parts and 0.02 parts of carbon black were mixed with isopropanol and uniformly dispersed. Non-volatile content 50
%, Viscosity 25 seconds / Ford cup # 4/20 ° C., and the coating color tone was Munsell chart N8.5. 16) Preparation of colored base paint (A-6) (for comparison) 35 parts (solid content) of acrylic resin solution (a-1), 35 parts (solid content) of polyester resin solution (b-1), 3030 parts of Cymel 370 (Solid content), titanium dioxide pigment 99.9
8 parts and 0.02 parts of carbon black were mixed with deionized water and uniformly dispersed. Non-volatile content 40%, viscosity 2
5 seconds / Ford Cup # 4/20 ° C., and the coating color tone was Munsell chart N8.5.

17) Preparation of Water-Based Thermosetting Colored Paint (B-1) Titanium oxide-coated scaly mica powder “Iliodin 103
R "(manufactured by Merck Ltd., trade name) in an amount of 50 parts of an acrylic resin solution (a-1N).
And dispersed. Further, 50 parts of a polyester resin solution (b-1N) and Cymel 370 3
4 parts were mixed, and then an acrylic resin emulsion (c-
1) After mixing 100 parts, deionized water was added, and the non-volatile content was 20%, the viscosity was 40 seconds / Ford cup # 4/20 ° C.
A water-based coloring paint was obtained.

18) Preparation of thermosetting clear coating material (C-1) 30 parts (solid content) of half ester (e-1) formed by addition reaction between polyol and 1,2-acid anhydride, epoxy group, 30 parts (solid content) of a vinyl polymer (f-1) having a hydroxyl group and a hydrolyzable alkoxysilyl group, a reactive organopolysiloxane "X41-1067" (trade name, product of Shin-Etsu Chemical Co., Ltd., glycidyl group and Methoxysilyl group-containing organopolysiloxane, molecular weight 740) 1
After preparing a resin mixed solution with 0 parts (solid content) and 3 parts (solid content) of the crosslinked fine particle polymer (g-1), 2 parts of an equivalent mixture of tetrabutylammonium bromide and monobutylphosphoric acid, "Tinuvin 900" ( 1 part of trade name, Ciba Geigy, ultraviolet absorber) and 0.1 part of BYK-300 (trade name, Big Chemie, surface conditioner) are added, and “Swazol 1000” (Cosmo Oil Co., Ltd.) (Trade name, hydrocarbon solvent) to obtain a thermosetting clear coating material having a nonvolatile content of 72% and a viscosity of 30 seconds (Ford Cup # 4/20 ° C.).

19) Preparation of Melamine Curable Thermosetting Clear Coating (C-2) (Comparative) 57 parts of acrylic resin solution (a-2), 50 parts of acrylic resin non-aqueous dispersion (d-1), Cymel 303 (Mitsui Cytec, trade name, melamine resin, solid content 88
%) 30 parts, 25% dodecylbenzenesulfonic acid solution 4
Section and BYK-300 (manufactured by Big Chemie Japan,
(Trade name) 0.5 part of the mixture was added to Swazole # 1000, and the non-volatile content was 55%, the viscosity was 30 seconds / Ford cup #
The temperature was adjusted to 4/20 ° C.

2. Examples and Comparative Examples Degreasing and zinc phosphate treated steel sheets (JIS G314
1, a 400 × 300 × 0.8 mm size cationic electrodeposition paint (“Elecron 9400HB” manufactured by Kansai Paint Co., Ltd., trade name, epoxy resin-based cationic resin using a blocked polyisocyanate compound as a curing agent) By electrodeposition coating to a film thickness of 20 μm (cured coating film), heating at 170 ° C. for 20 minutes for cross-linking and curing, and then applying an intermediate coating material (“Lugabake intermediate coating” Kansai Paint) Co., Ltd., trade name, polyester resin / amino resin type, organic solvent type, Munsell chart N of coating film was made to be the same as each colored base coating material (A)) and film thickness 40 μm (cured coating film) 1)
It was crosslinked and cured by heating at 40 ° C. for 30 minutes.

The colored base paints (A-1) to (A-6) were applied to the coated steel sheet thus obtained by using a mini-bell rotating electrostatic coating machine while changing the humidity in the booth. The coating thickness was 10 μm based on the cured coating. After applying the colored base paint, leave it in the booth for 1 minute, then in a wet-on-wet state, apply the water-based colored paint (B-1) in one stage using an air atomizing electrostatic coating machine as the colored base paint. It was painted with the humidity in the booth. The coating thickness was 10 μm based on the cured coating. After applying the water-based coloring paint, leave it in the booth for 1 minute, then heat it in a hot-air circulating drying oven at 80 ° C for 10 minutes to volatilize most of the volatile components (the gel content of the coating film by acetone reflux extraction). Rate is 5% or less), and after the temperature of the coating film is brought to room temperature, the thermosetting clear coating material (C-1) or (C-2) is coated on the coated surface by using a mini-bell rotating electrostatic coating machine. did. The coating thickness is 40 based on the cured coating
μm. After leaving it at room temperature for 5 minutes, it is heated at 140 ° C. for 30 minutes in a circulating hot air drying oven for 30 minutes to give a colored base paint (A), a water-based thermosetting colored paint (B-1) and a thermosetting clear paint (C). Was simultaneously cross-linked and cured.

Table 1 shows the workability of the coating and the performance of the coating film obtained in these steps together with the respective steps.

The test method is as follows.

Waki critical film thickness: A colored base paint (A) and a water-based thermosetting colored paint (B) were each applied to a stationary horizontal surface at a thickness of 10 μm and dried, and then the film thickness of the thermosetting clear paint (C) was measured. Critical film thickness (μ)
m).

Pearl gloss: ALCOPE LMR100
(Manufactured by Fuji Industry Co., Ltd., trade name), the IV value was measured. When this value increases, it indicates that the pearl luster is excellent.

Smoothness: Measured by a tension meter manufactured by RENAULT. An increase in this value indicates that the smoothness is excellent.

Visibility: Sharpness gloss meter P.I. G. FIG. It measured by D-IV. When this value is increased, it indicates that the sharpness is excellent.

Acid resistance: 1% of test coated plate in 40% sulfuric acid solution
After immersion for 2 hours and left at 50 ° C. for 5 hours, it was washed with water and the coated surface was observed. The evaluation criteria are as follows.

A indicates that there is no change, B indicates that there is no abnormality in the coated surface, but a slight step is recognized at the boundary between the immersed portion and the non-immersed portion, and C indicates that the coated surface is whitened.

Scratch resistance: After the automobile coated with the test coated plate on the roof was washed 15 times with a car washer, the coated surface of the coated plate was observed. The car washer was manufactured by Yasui Sangyo
0FWRC "was used. The evaluation criteria are as follows.

A shows almost no scratches by visual observation, B
Shows slight scratches, but the degree is very slight, and C indicates that the scratches are conspicuous by visual observation.

[0162]

[Table 1]

[0163]

According to the present invention, smoothness, pearl luster,
Provided is a method for forming a coating film which has excellent water resistance, acid resistance, abrasion resistance, etc., does not easily flow even when the humidity at the time of coating is high, and does not cause roughening of the coated surface even when coated at low humidity. A remarkable effect is produced.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 201/06 C09D 201/06 201/10 201/10 (72) Inventor Mitsuru Endo 4-7-11-1 Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Kansai Paint Co., Ltd. (72) Inventor Mikio Shimakawa 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Kansai Paint Co., Ltd.

Claims (1)

[Claims] 1. A thermosetting organic solvent-based colored base coating material containing a neutralized product of a hydroxyl group-containing resin having an acid value of 5 to 100 and a crosslinking agent selected from block polyisocyanate and amino resin. A) is applied, and the uncured colored coating surface is
Apply a thermosetting water-based coloring paint (B) and apply 5
(C-1) a resin having a carboxyl group, (C-2) a vinyl polymer having an epoxy group, a hydroxyl group and a hydrolyzable alkoxysilyl group in one molecule, C-3) A thermosetting organic solvent-based clear coating material (C) having a solid content of 65 to 90% by weight, containing a reactive organopolysiloxane and (C-4) a crosslinked fine particle polymer. And then heating to simultaneously cure the three-layer coating consisting of (A), (B) and (C).