JP2003096393A - Method for forming thermoset coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a thermoset coating film which is hard to cause sagging in coating automobiles, bicycles, and the like, and simultaneously, can obtain a smooth coating surface. SOLUTION: This method for forming the thermoset coating film comprises coating a coating material composition comprising (A) a compound having two or more alkoxysilyl groups per molecule, (B) a thermosetting resin composition, (C) a photoacid generator, and (D) an organic solvent at a solid content weight ratio of the compound (A) to the thermosetting resin composition (B) of 0.5/99.5 to 20/80 with 0.1-10 pts.wt., based on 100 pts.wt. compound (A), photoacid generator (C) on a substance to be coated, then irradiating the coating liquid with light to thicken the coating liquid, and subsequently heating and curing the resulting coating liquid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thermosetting coating film without sagging, which is particularly suitable for forming a high solid coating type thermosetting coating film on automobiles, motorcycles, containers and the like. Is.

[0002]

2. Description of the Related Art Conventionally, as a method for preventing the sagging of a paint, a high-molecular-weight resin, organic fine particles, an extender pigment, etc. are mixed in the paint to prevent the sagging of the paint from the painting process to the baking process. Have been prevented. In recent years, in order to improve the global environment, it has been demanded to reduce the amount of organic solvent used, and it is also desired to increase the solid content of the coating composition in coating materials to reduce the amount of organic solvents. Mixing a high-molecular-weight resin, organic fine particles, extender pigment, etc. as the anti-sagging agent in a paint with a high solid content will result in an increase in the viscosity of the paint, which may make painting difficult. However, there was a problem that the painted surface became uneven even if it could be painted.

In order to solve these problems, a photopolymerizable monomer is contained in the paint and the paint droplets sprayed from a spray gun are irradiated with light to crosslink the photopolymerizable monomer. Has proposed a method for preventing sagging (see Japanese Patent Laid-Open No. 6-65523). However, with this method, it is difficult to uniformly irradiate the paint droplets with light, and since the viscosity of the coating liquid applied to the object to be coated greatly increases, the fluidity decreases and a smooth coating surface is obtained. There is a problem that it is hard to be caught.

An object of the present invention is to provide a method for forming a thermosetting coating film which can solve the above-mentioned problems and is less likely to cause sagging when coating automobiles, motorcycles and the like, and which can obtain a smooth coating surface. That is.

[0005]

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention applied a coating composition containing a compound having two or more alkoxysilyl groups in one molecule to an object to be coated and then applied it. It was found that not only can the coating liquid be prevented from sagging, but also a smooth coating film with no unevenness can be formed by irradiating the coating liquid with light to partially polymerize the compound to increase the viscosity of the coating film, thus completing the present invention. Came to.

Thus, according to the present invention, (A) a compound having two or more alkoxysilyl groups in one molecule,
A coating composition containing (B) a thermosetting resin composition, (C) a photoacid generator, and (D) an organic solvent, which is a solid of the compound (A) and the thermosetting resin composition (B). The weight ratio is (A) / (B) = 0.5 / 99.5 to 20/80, and the photoacid generator (C) is 0.1 to 10 parts by weight with respect to 100 parts by weight of the compound (A). After coating a coating composition within the range of parts on the article to be coated, the coating solution is irradiated with light to increase the viscosity of the coating solution, and then heated and cured to form a thermosetting coating film. Will be provided.

The method of the present invention will be described in detail below.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for forming a thermosetting coating film of the present invention, a compound (A) having two or more alkoxysilyl groups in one molecule, a thermosetting resin composition (B), a photoacid generator. A coating composition containing (C) and an organic solvent (D) is used.

Compound (A) Compound (A) which is a raw material of the coating composition used in the present invention
Is a compound having two or more alkoxysilyl groups in one molecule, for example, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, Alkylalkoxysilanes such as dimethyldimethoxysilane, phenylethoxysilane, diphenyldiethoxysilane, decyltrimethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4 -Epoxycyclohexyl) ethyl group-containing alkylalkoxysilanes such as ethyltrimethoxysilane; vinyltrimethoxysilane, vinyltriethoxysilane, 3- (meth) acryloylpropyne Trimethoxysilane, 3- (meth)
Acryloylpropyltriethoxysilane, 3- (meth) acryloylpropylmethyldimethoxysilane, 3
-(Meth) acryloylpropylmethyldiethoxysilane and other alkoxysilanes having an ethylenically unsaturated group; 3-isocyanatopropyltrimethoxysilane,
3-isocyanatopropyltriethoxysilane, 3-
Isocyanatopropylmethyldimethoxysilane, 3-
Isocyanate propylalkoxysilanes such as propylmethyldiethoxysilane; mercapto-containing alkoxy such as 3-mercaptopropyltrimethoxysilane, 3-chloro-mercaptopropyltrimethoxysilane, 3-hydroxy-mercaptopropyltrimethoxysilane Silanes; vinyltrimethoxysilane, vinyltriethoxysilane, 3- (meth) acryloylpropyltrimethoxysilane, 3- (meth)
Acryloylpropyltriethoxysilane, 3- (meth) acryloylpropylmethyldimethoxysilane, 3
Polymers of alkoxysilanes having an ethylenically unsaturated group such as-(meth) acryloylpropylmethyldiethoxysilane or styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl ( (Meth) acrylate,
Lauryl (meth) acrylate, cyclohexyl (meth) acrylate, cyclohexenyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate,
ε-caprolactone modified tetrahydrofurfuryl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, dicyclopentenyl (meth) acrylate,
Copolymers with compounds having an ethylenically unsaturated group such as dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate and benzyl (meth) acrylate; 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltri Alkoxysilanes having an isocyanate group such as ethoxysilane, 3-isocyanatepropylmethyldimethoxysilane, and 3-isocyanatepropylmethyldiethoxysilane, and ethylene glycol, propylene glycol,
1,4-butanediol, 1,6-hexanediol,
Examples thereof include reaction products with polyols such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, and sorbitol. These can be used alone or in combination of two or more.

Thermosetting Resin Composition (B) The thermosetting resin composition (B) is one which can be cured by heating to form a coating film, and examples thereof include a hydroxyl group-containing acrylic resin and a hydroxyl group-containing polyester resin. Examples include a combination of a hydroxyl group-containing resin with a cross-linking agent such as a polyisocyanate compound, a combination of a carboxyl group-containing compound such as a carboxyl group-containing acrylic resin and a carboxyl group-containing polyester resin with an epoxy group-containing compound. it can.

The acrylic resin is a copolymer of a polymerizable unsaturated monomer, and the hydroxyl group-containing acrylic resin is obtained by using a hydroxyl group-containing unsaturated monomer as a part of the polymerizable unsaturated monomer. Further, the carboxyl group-containing acrylic resin is a polybasic acid anhydride obtained by using a carboxyl group-containing unsaturated monomer as a part of the polymerizable unsaturated monomer, or by a half-esterification reaction to the hydroxyl group of the hydroxyl group-containing acrylic resin. Can be synthesized by ring-opening addition. Examples of the polybasic acid anhydrides include phthalic anhydride, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, het anhydride, trimellitic anhydride, pyromellitic anhydride, and succinic anhydride. .

Examples of the hydroxyl group-containing unsaturated monomer include 2-hydroxyl ethyl (meth) acrylate,
Examples thereof include hydroxylpropyl (meth) acrylate and butanediol mono (meth) acrylate.

Examples of the unsaturated monomer containing a carboxyl group include acrylic acid, methacrylic acid, crotonic acid,
Examples thereof include itaconic acid, maleic acid and fumaric acid.

Other polymerizable unsaturated monomers include, for example, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate,
2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, cyclohexenyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, ε-caprolactone-modified tetrahydrofurfuryl (meth) acrylate, phenoxyethyl ( (Meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, hydroxyethyl (meth) acrylate and ε -Adduct with caprolactone, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3
-Butoxypropyl (meth) acrylate, monohydroxyethyl phthalate (meth) acrylate, Aronix M110 (manufactured by Toagosei Co., Ltd.), N-methylol (meth)
Acrylamide, N-methylol (meth) acrylamide butyl ether, acryloylmorpholine, dimethylaminoethyl (meth) acrylate, N-vinyl-2-
Examples thereof include pyrrolidone.

As the polyester resin, those obtained by synthesizing a polybasic acid component and a polyhydric alcohol component by a conventional direct esterification method or transesterification method can be used.

The polybasic acid component is selected from, for example, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, sebacic acid and maleic anhydride. One or more dibasic acids and lower alkyl ester compounds of these acids are mainly used, and if necessary, trivalent or more polybasic acids such as trimellitic anhydride, methylcyclohexene tricarboxylic acid, and pyromellitic dianhydride. Are used together. In addition, as the acid component, a monobasic acid such as benzoic acid, crotonic acid, or pt-butylbenzoic acid can be used together for the purpose of adjusting the molecular weight, and oil fatty acids such as coconut oil fatty acid and dehydrated castor oil fatty acid are used. It is also possible to do so.

Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol and 1,6-hexanediol. And other polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol can be used in combination. These polyhydric alcohols can be used alone or in admixture of two or more. Further, some of the above acid components and alcohol components are dimethylolpropionic acid, oxypivalic acid, paraoxybenzoic acid, etc .; lower alkyl esters of these acids;
It can also be replaced by an oxyacid component such as a lactone such as caprolactone.

The hydroxyl group-containing polyester resin is obtained by reacting a polybasic acid and a polyhydric alcohol in excess of the polyhydric alcohol, and the carboxyl group-containing polyester resin is a polybasic acid and a polyhydric alcohol. It is synthesized by reacting with an excess of acid or by ring-opening addition of a polybasic acid anhydride to the hydroxyl group of the hydroxyl group-containing polyester resin by a half-esterification reaction. As the polybasic acid anhydride used for half-esterification, the same one as used for the synthesis of the acrylic resin can be used.

It is also possible to use, as the carboxyl group-containing compound, the polybasic acid mentioned as the raw material for the polyester resin as it is.

As the amino resin to be combined with the hydroxyl group-containing resin, melamine resin, guanamine resin, urea resin and the like can be used, and among them, melamine resin is preferable from the viewpoint of weather resistance and the like. Further, a curing catalyst may be used in combination with these amino resins.

Examples of the polyisocyanate compound include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; cycloaliphatic diisocyanates such as hydrogenated xylylene diisocyanate or isophorone diisocyanate; tolylene diisocyanate or 4,4'- Organic diisocyanates such as aromatic diisocyanates such as diphenylmethane diisocyanate itself, or adducts of these respective organic diisocyanates with polyhydric alcohols, low molecular weight polyester resins, water, etc., or cyclized polyisocyanates of the respective organic diisocyanates as described above. Examples of the compounding agent include isocyanate, biuret, and the like. Blocking agents for these polyisocyanate compounds It can be used those blocks. When using a blocked isocyanate compound, it is preferable to use a dissociation catalyst together.

The epoxy group-containing compound to be combined with the carboxyl group-containing compound is not particularly limited as long as it has an average of two or more epoxy groups in one molecule, but from the viewpoint of weather resistance, the epoxy group-containing compound is included. An acrylic resin obtained by copolymerizing an unsaturated monomer and another unsaturated monomer is suitable. Examples of the epoxy group-containing unsaturated monomer include glycidyl (meth) acrylate, methylglycidyl (meth) acrylate, and the like, and other unsaturated monomers include the unsaturated groups used in the description of the acrylic resin. Monomers can be used.

The ratio of the compound (A) having two or more alkoxysilyl groups in one molecule to the thermosetting resin composition (B) is (A) / (B) = 0.5 / in terms of solid weight ratio. 99.5
-20/80, preferably 2/98 to 15/85 is suitable from the viewpoint of the balance between thickening due to photocuring and coating performance such as weather resistance and hardness of the final coating.

Photoacid Generator (C) The photoacid generator (C) is a photopolymerization initiator which generates an acid upon irradiation with light. As the photo-acid generator (C), for example,
Examples thereof include compounds represented by the following formulas (1) to (15).

Ar_Two  I⁺・ X⁻        (1) (In the formula, Ar represents an aryl group, for example, a phenyl group,
X⁻Is BF_Four ⁻  , PF ₆ ⁻  , SbF₅(OH)
⁻  , SbF₆ ⁻  , AsF₆ ⁻Or the following formula

[0026]

[Chemical 1]

Represents a group represented by: Ar ₃ S ⁺ · X ⁻ (2) (wherein Ar and X ⁻ have the same meanings as described above)

[0028]

[Chemical 2]

(Wherein R ¹ is an aralkyl group having 7 to 15 carbon atoms or an alkenyl group having 3 to 9 carbon atoms, R ²
Represents a hydrocarbon group having 1 to 7 carbon atoms or a hydroxyphenyl group, R ³ represents an alkyl group having 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom, and X ⁻ has the same meaning as above. Have)

[0030]

[Chemical 3]

(Where Y⁻  Is PF₆ ⁻  , SbF
₅(OH)⁻  , SbF₆ ⁻  Or AsF ₆ ⁻Represents)

[0032]

[Chemical 4]

(Wherein X ⁻ has the same meaning as described above)

[0034]

[Chemical 5]

(Wherein X ^- has the same meaning as described above)

[0036]

[Chemical 6]

[0037]

[Chemical 7]

(In the formula, R ⁴ and R ⁵ are each independently an alkyl group having 1 to 12 carbon atoms or 1 to 12 carbon atoms.
12 represents an alkoxyl group)

[0039]

[Chemical 8]

[0040]

[Chemical 9]

(In the formula, X ⁻ has the same meaning as described above)

[0042]

[Chemical 10]

(In the formula, R ⁶ represents an alkyl group having 1 to 12 carbon atoms or an alkoxyl group having 1 to 12 carbon atoms, n represents an integer of 0 to 3, and X ⁻ has the same meaning as described above).

[0044]

[Chemical 11]

(In the formula, R ⁷ and R ⁸ are each independently an alkyl group having 1 to 12 carbon atoms or 1 carbon atom.
~ Represents an alkoxyl group of 12)

[0046]

[Chemical 12]

[0047]

[Chemical 13]

Commercially available products of the above photo-acid generator include, for example, Syracure UVI-6970 and UVI-697.
4, the same UVI-6990, the same UVI-6950 (above,
All of them are manufactured by Union Carbide Co., USA), ADEKA OPTOMER SP-150, SP-170 (all produced by Asahi Denka Co., Ltd.), CI-2855 (Nippon Soda Co., Ltd.), P
I-2074 (Pentafluorophenyl borate toluyl cumyl iodonium salt manufactured by Roger Co., Ltd.), FC-5
09 (manufactured by 3M), BBI-102 (manufactured by Midori Kagaku), Irgacure 261 (manufactured by Ciba Specialty Chemicals) and the like. The photo-acid generator (C) can be used alone or in combination of two or more kinds.

The photoacid generator (C) is used in an amount of 0.1 to 10 parts by weight, preferably 0.3 to 7 parts by weight, based on 100 parts by weight of the compound (A) having two or more alkoxysilyl groups. From the viewpoint of photocurability, it is preferable to add and use parts.

Organic Solvent (D) The organic solvent (D) is an inert organic solvent which does not substantially react with the radical-polymerizable unsaturated group-containing compound (A) and the thermosetting resin composition (B). If there is no particular limitation, it can be used. Specifically, for example, aromatic solvents such as toluene and xylene; ethyl acetate, propyl acetate, butyl acetate, methoxybutyl acetate, amyl acetate, methyl cellosolve acetate, cellosolve acetate, diethylene glycol monomethyl ether acetate, carbitol acetate, etc. Acetate solvent; ether solvent such as dioxane, ethylene glycol diethyl ether, ethylene glycol dibutyl ether; acetone, methyl ethyl ketone,
Examples include ketone solvents such as methyl isobutyl ketone. These can be used alone or in combination of two or more.

The content of the organic solvent in the coating material of the present invention is preferably 40% by weight or less in the coating material. When the amount of the organic solvent is 40% by weight or more, that is, when the solid content is 60% by weight or less, it is not much different from the content of the organic solvent in the conventional paint, and it is not so effective in improving the global environment for the purpose of reducing the amount of the organic solvent.

The coating composition used in the present invention may further contain known pigments, ultraviolet absorbers, surface modifiers, alkoxylyl compounds, organic compounds and the like, if necessary.

In the method of the present invention, the coating composition can be applied to an object to be coated such as automobiles, motorcycles and containers by a coating method such as a spray coating method or a curtain coating method. Method is preferred.
In addition, the viscosity of the coating solution immediately after spray coating the above coating composition on an article is 1 to 10 Pa from the viewpoint of coating smoothness.
s, preferably in the range of 2 to 7 Pa · s.
The viscosity of the coating liquid is scraped off immediately after coating, preferably within 10 seconds after coating, using an E-type viscometer (Toki Sangyo RE
80 type rotation speed: 1 RPM).

By irradiating the coating liquid on the article coated by the above method with light, the coating liquid thickens and sagging during setting and / or heat drying can be prevented. The viscosity of the coating liquid after irradiation is 40 to 100 Pa.
s, preferably in the range of 50 to 80 Pa · s, is highly effective in preventing sagging and is suitable. The viscosity of the coating liquid can be measured in the same manner as the viscosity of the coating liquid immediately after coating.

Especially for those which are liable to sag during setting, it is preferable to irradiate with light as early as possible after coating, but in general, many of them are liable to sag during heating and drying. In that case, the time is appropriately opened. Alternatively, it is more suitable to move the light to another place and irradiate it with light from the viewpoints of safety against fire and contamination of the irradiation device by paint mist. The wavelength for irradiating light is usually 200 to
An ultraviolet ray range of 450 nm is suitable, and an irradiation source having a highly sensitive wavelength can be appropriately selected and used according to the type of the photopolymerization initiator. Examples of the irradiation source of ultraviolet rays include a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a xenon lamp, a carbon arc, a metal halide lamp, and sunlight. The UV irradiation conditions for the coating film are
Usually, dose 100~2,000mJ / cm ^2, preferably is suitable range of the 500~1,500mJ / cm ^2.

The object to be exposed to light is subsequently heated and dried, and the resin in the coating solution is crosslinked to form a tough coating film. The heating means is not particularly limited, for example, hot air stove,
Drying equipment such as an electric furnace and infrared induction heating can be applied.
The heating temperature is usually about 50 to 200 ° C., preferably 7
It is suitable to be in the range of about 0 to 150 ° C. The heating time is not particularly limited, but is usually 15 to 15.
A range of 45 minutes is preferred.

[0057]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited to these. In the following, "parts" and "%" are based on weight.

Production Example of Alkoxysilyl Group-Containing Compound Production Example 1 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device was charged with 480 parts of butyl acetate and heated to 130 ° C. while blowing nitrogen gas. After warming, while maintaining the temperature, a mixed solution of the following monomer and initiator was dropped from the dropping device over 3 hours.

[0059] After completion of dropping, aging at 130 ° C. for 1 hour, resin solid content 70
% Of an alkoxysilyl group-containing copolymer solution was obtained. The number average molecular weight of the obtained resin measured by GPC (gel permeation chromatography) was about 3,000, and the number of alkoxysilyl groups was about 11 on average.

Production Example 2 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device was charged with 118 parts of 1,6-hedisandiol, 410 parts of 3-isocyanatopropyltrimethoxysilane and 132 parts of butyl acetate. Part, charged with nitrogen gas and heated to 80 ° C., then kept at 80 ° C. for 5 hours, cooled down after confirming that the added isocyanate had substantially reacted, and alkoxysilyl having a resin solid content of 80% A group-containing oligomer solution was obtained. Average molecular weight is about 52
The average number of 8 and alkoxysilyl groups was about 6.

Production of Thermosetting Resin Production Example 3 480 parts of butyl acetate was charged into a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device, and heated to 130 ° C. while blowing nitrogen gas. After that, while maintaining the temperature, a mixed solution of the following monomer and initiator was added dropwise from the dropping device over 3 hours.

[0062] After completion of dropping, aging at 130 ° C. for 1 hour, resin solid content 70
% Hydroxyl group-containing copolymer solution was obtained. G of the obtained resin
The number average molecular weight measured by PC (gel permeation chromatography) was about 3,000, and the hydroxyl value was 108.

Production Example 4 296 parts of phthalic acid, 292 parts of adipic acid, 186 parts of ethylene glycol and 312 parts of neopentyl glycol were placed in a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a water separator. The temperature was raised to 160 ° C. Then, after dehydrating over 2 hours and raising the temperature to 220 ° C., a small amount of xylene was put in the reaction vessel, azeotropy of condensed water was carried out, and it was confirmed that substantially all the added acid had reacted and cooled. Then, xylene was added to obtain a hydroxyl group-containing polyester resin solution having a resin solid content of 80%. GPC of the obtained resin
(Gel Permeation Chromatograph) The number average molecular weight was about 1,000 and the hydroxyl value was 112.

Production Example 5 480 parts of butyl acetate were charged into a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, and a dropping device, and the temperature was raised to 130 ° C. while blowing nitrogen gas. While maintaining the above, a mixed solution of the following monomers and an initiator was dropped from the dropping device over 3 hours.

[0065] After completion of dropping, aging at 130 ° C. for 1 hour, resin solid content 70
% Carboxyl group-containing copolymer solution was obtained. The number average molecular weight of the obtained resin measured by GPC (gel permeation chromatography) was about 3,000, and the acid value was 104.

Production Example 6 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and a dropping device was charged with 480 parts of butyl acetate and heated to 130 ° C. while blowing nitrogen gas. While maintaining the above, a mixed solution of the following monomers and an initiator was dropped from the dropping device over 3 hours.

[0067] After completion of dropping, aging at 130 ° C. for 1 hour, resin solid content 70
% Epoxy group-containing copolymer solution was obtained. The number average molecular weight of the obtained resin measured by GPC (gel permeation chromatography) was about 3,000, and the epoxy equivalent was 530.

Preparation of coating material Preparation Example 1 Copolymer solution containing alkoxysilyl group of Preparation Example 1 5.7
Parts, 2 parts of dimethyldimethoxysilane, 100 parts of the hydroxyl group-containing copolymer solution of Production Example 3 and 23 parts of Cymel 235 (methyl / butylated melamine resin manufactured by Mitsui Cytec Co., Ltd.) were stirred and mixed, and then CI-2855 (Nippon Soda Co., Ltd.). 0.3 parts of TINUVIN 400 (manufactured by Ciba Specialty Chemicals) as an additive such as an ultraviolet absorber, and 0.3 parts of TINUVIN 144 (manufactured by Ciba Specialty Chemicals) ) Was added and dissolved, diluted with xylene, and the viscosity was adjusted to 25 seconds with a Ford cup # 4 (20 ° C.) having an appropriate viscosity for spray coating.
The solid content in the paint was 65%.

Preparation Example 2 Alkoxysilyl group-containing oligomer solution of Preparation Example 2.
8 parts, 3 parts of phenyltrimethoxysilane, 100 parts of the hydroxyl group-containing copolymer solution of Production Example 3 and Sumidule N-7.
After stirring and mixing 32 parts of 5 (solid content 75%, Sumitomo Bayer Urethane Co., polyisocyanate compound), PI-20
After adding 0.5 parts of 74 (manufactured by Roger Co., photo-acid generator) and dissolving, 0.6 parts of tinuvin 400 and 0.3 parts of tinuvin 144 as additives such as an ultraviolet absorber are further added and dissolved. Then, it was diluted with xylene, and the viscosity was adjusted to 25 seconds using Ford Cup # 4 (20 ° C.), which is an appropriate viscosity for spray coating. The solid content in the paint was 67%.

Preparation Example 3 10 parts of decyltrimethoxysilane, 80 parts of the hydroxyl group-containing polyester resin solution of Preparation Example 4 and Cymel 235 (Mitsui Cytec, methyl / butylated melamine resin) 2
After stirring and mixing 6 parts, PI-2074 (manufactured by Roger,
0.3 parts of TINUVIN 400 and 0.3 parts of TINUVIN 144 as additives such as an ultraviolet absorber are further added and dissolved, and diluted with xylene. Ford cup # 4 (20 ° C.), which is an appropriate viscosity for spray coating, was used for 25 seconds. The solid content in the paint was 75%.

Preparation Example 4 5 parts of methyltriethoxysilane, 84 parts of the hydroxyl group-containing polyester resin solution of Preparation Example 4 and Sumidule N-75
(Solid content: 75%, polyisocyanate compound manufactured by Sumitomo Bayer Urethane Co., Ltd.) After stirring and mixing 37 parts, 0.3 part of Syracure UVI-6970 (manufactured by Union Carbide Co., photo-acid generator) was added and dissolved, and further. 0.6 parts of TINUVIN 400 and 0.3 parts of TINUVIN 144 as an additive such as an ultraviolet absorber are added and dissolved, diluted with xylene, and sprayed with Ford Cup # 4 having an appropriate viscosity for spray coating.
(20 ° C.) 25 seconds. The solid content of the paint is 7
It was 4%.

Preparation Example 5 10 parts of phenyltrimethoxysilane, 64 parts of the carboxyl group-containing copolymer solution of Production Example 5 and 64 parts of the epoxy group-containing copolymer solution of Production Example 6 were stirred and mixed, and then CI-28 was used.
After adding 0.3 parts of 55 (manufactured by Nippon Soda Co., Ltd., a photo-acid generator) and dissolving, 0.6 parts of tinuvin 400 and 0.3 parts of tinuvin 144 were further added as additives such as an ultraviolet absorber. Dissolved, diluted with xylene and 25 seconds in Ford Cup # 4 (20 ° C), the proper viscosity for spray painting. The solid content in the paint was 70%.

Preparation Example 6 (Comparative) 100 parts of the hydroxyl group-containing copolymer solution of Preparation Example 3 and 23 parts of Cymel 235 (methyl / butylated melamine resin manufactured by Mitsui Cytec Co., Ltd.) were stirred and mixed, and then CI-2855 (Japan). 0.3 parts of photo acid generator manufactured by Soda Co., Ltd. was added and dissolved, and then Tinuvin 40 was added as an additive such as an ultraviolet absorber.
0.6 parts of 0 and 0.3 parts of TINUVIN 144 were added to dissolve and diluted with xylene, and the viscosity was adjusted to 25 seconds with Ford cup # 4 (20 ° C.), which is an appropriate viscosity for spray coating. The solid content in the paint was 67%.

Preparation Example 7 (for comparison) Mizukasil P526 (manufactured by Mizusawa Chemical Co., Ltd.) as an anti-sagging agent
5 parts of the hydroxyl group-containing polyester resin solution 8 of Production Example 4
After stirring and mixing 4 parts and 37 parts of Sumidule N-75 (solid content 75%, polyisocyanate manufactured by Sumitomo Bayer Urethane Co., Ltd.), 0.3 part of CI-2855 (photo acid generator manufactured by Nippon Soda Co., Ltd.) was added. Then, 0.6 part of TINUVIN 400 and 0.3 part of TINUVIN 144 as additives such as an ultraviolet absorber are added and dissolved, diluted with xylene, and then diluted with xylene to give a suitable viscosity for spray coating Ford cup. # 4
(20 ° C.) 25 seconds. Solid content in paint is 4
It was 5%.

Preparation Example 8 (for comparison) Mizukasil P526 (manufactured by Mizusawa Chemical Co., Ltd.) as an anti-sagging agent
5 parts of the hydroxyl group-containing polyester resin solution 8 of Production Example 4
After stirring and mixing 4 parts and 37 parts of Sumidule N-75 (solid content 75%, manufactured by Sumitomo Bayer Urethane Co., polyisocyanate compound), 0.3 part of CI-2855 (manufactured by Nippon Soda Co., Ltd., a photoacid generator) was added. Then, 0.6 part of TINUVIN 400 and 0.3 part of TINUVIN 144 as additives such as an ultraviolet absorber are added and dissolved, and the mixture is diluted with xylene so that the solid content in the paint is 60%. %. The viscosity of this paint was 100 seconds in Ford Cup # 4 (20 ° C).

Formation of Thermosetting Coatings Examples 1-5 and Comparative Examples 1-3 Zinc Phosphate Chemical Treatment 0.8 mm, 25 cm
Epoxy cationic electrodeposition coating is applied on square dull steel plates to a dry film thickness of about 20 μm, and the temperature is maintained at 170 ° C for 20
After baking for a minute, sharpen with # 400 sandpaper,
Degreased by wiping with petroleum benzine. An intermediate coating surfacer for automobiles was air-spray coated thereon to a dry film thickness of about 25 μm, baked at 140 ° C. for 30 minutes, sanded with # 400 sandpaper, and drained and dried. Further, a white base coat paint is applied thereon to a film thickness of 20 μm, and the coating film is cured by heating at 140 ° C. for 30 minutes, followed by sanding with # 400 sandpaper, draining and drying, and petroleum oil. It was wiped with benzine to be degreased and used as a test material.

Next, this material is placed vertically, and the upper side 15c
m is coated with the paints prepared in the above Preparation Examples 1 to 8 by air spray so that the cured coating film is 40 μm, and immediately after that, 100 W is applied with a 120 W / cm metal halide lamp.
After irradiating with 0 mJ / cm ² ultraviolet rays, the coated plate was placed vertically in a drying oven with the coated part facing up, and at 140 ° C. for 30 minutes.
The coating film was cured by heating for a minute to form a top coating film.
The coated plates coated with the paints prepared in Comparative Preparation Examples 6 to 8 were not irradiated with ultraviolet rays and were placed vertically in a drying oven with the coated part facing upward at 140 ° C. for 30 minutes. The coating film was heated and cured to form a top coating film.

The following methods were used to measure the solid content of each coating used in the above test, the evaluation of sag, the evaluation of smoothness, the evaluation of curability, and the change in the viscosity of the coating film before and after light irradiation. I went. The results are shown in Table 1 below.

Solids content: 1.5 g of the paint was weighed in a tin plate with a diameter of 9 cm and after heating at 130 ° C. for 3 hours, the remaining amount was weighed and expressed as a percentage divided by the initial amount.

Evaluation of Sagging: How many cm the sagging of the paint was measured on the uncoated 10 cm at the bottom of the material.

Smoothness of coating film: The surface condition of the coating film was visually evaluated.

60 degree specular gloss: JIS K-5400
It measured according to 7.6 (1990).

Xylene rubbing property: After wiping the coated surface 50 times back and forth with gauze containing xylene, the coated surface was observed. The evaluation criteria are as follows. ◯: No change on the coated surface and good, Δ: Scratch is recognized on the coated surface and the curability is poor, ×: The coating surface is dissolved in xylene and the curability is significantly poor.

Viscosity of coating liquid before and after irradiation with light In order to confirm the change in viscosity of the coating liquid due to irradiation with light, a glass plate was coated with the coating composition prepared in the above Preparation Examples 1 to 8 to 40 μm by air spray. Then, the coating liquid is scraped off within 10 seconds to measure the viscosity with an E-type viscometer (RE8 manufactured by Toki Sangyo Co., Ltd.).
0 type, rotation speed: 1 RPM). In addition, another glass plate was coated in the same manner as above, irradiated with 1000 mJ / cm ² ultraviolet rays, and the coating liquid was scraped off from the glass plate to obtain a viscosity of E.
It was measured by a viscometer. The results are shown in Table 2.

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[Table 1]

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[Table 2]

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EFFECTS OF THE INVENTION By using the method of the present invention, a thermosetting coating material having a high solid content can be applied without sagging, and a smooth and glossy coated surface can be formed. Therefore, it is extremely useful particularly as a method for forming a thermosetting coating film on automobiles, motorcycles, containers and the like.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kei Maruyama             Seki, 4-17-1, Higashi-Hachiman, Hiratsuka City, Kanagawa Prefecture             West Paint Co., Ltd. F-term (reference) 4J038 CG001 CG142 CL002 DA132                       DA142 DA162 DA172 DD001                       DG262 GA03 GA06 GA15                       JC32 JC34 JC35 JC36 KA03                       KA06 NA01 NA23 PA17 PB07                       PC02

Claims (3)

[Claims] 1. A compound having (A) two or more alkoxysilyl groups in one molecule, (B) a thermosetting resin composition,
A coating composition containing (C) a photo-acid generator and (D) an organic solvent, wherein a solid content weight ratio of the compound (A) and the thermosetting resin composition (B) is (A) / (B ) = 0.5 / 9
9.5 to 20/80, and after coating the coating composition with a coating composition in which the photoacid generator (C) is in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the compound (A). A method for forming a thermosetting coating film, which comprises heating the coating solution by irradiating the coating solution with light to increase the viscosity of the coating solution and then curing the coating solution. 2. The coating liquid viscosity of the coating liquid immediately after the coating composition is applied to an object to be coated is 1 to 10 Pa.s, and the viscosity of the coating liquid after light irradiation of the coating liquid is 40 to 100 Pa.s. It is in the range of s, The thermosetting coating film forming method of Claim 1 characterized by the above-mentioned. 3. The solid content of the coating composition is 60% by weight.
It is above, The thermosetting coating film forming method of Claim 1 or 2 characterized by the above-mentioned.