JP2003245606A - Method for forming thermoset coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a thermoset coating film, hard to generate dropping at the time of coating of a car, a two-wheeled vehicle or the like and capable of obtaining a smooth coating surface. <P>SOLUTION: A coating composition contains a photosetting composition (A), a thermosetting resin composition (B), a photopolymerization initiator (C), a photically acid generating agent (D) and an organic solvent (E). The photosetting composition (A) comprises a compound (A-1) having two or more radical polymerizable unsaturated groups in one molecule thereof and having a number average molecular weight of 250-2,000 and at least one compound (A-2) selected from a compound having an epoxy group, a compound having an oxetanyl group and a compound having two or more alkoxysilyl groups in one molecule thereof. After the coating composition is applied to an object to be coated, the applied coating solution is irradiated with light to be increased in viscosity and cured under heating to form the thermoset coating film. <P>COPYRIGHT: (C)2003,JPO

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 present inventors have found that a compound having a large number of radically polymerizable unsaturated groups in one molecule, a compound having an epoxy group, a compound having an oxetanyl group, and At least one selected from compounds having two or more alkoxysilyl groups in one molecule
After coating the coating composition containing both of the compounds of the type on the article to be coated, it is possible to prevent the sagging of the coating by irradiating the coating liquid with light to partially polymerize the compound to increase the viscosity of the coating film. In addition, they have found that a smooth coating film having no unevenness can be formed, and have completed the present invention.

Thus, according to the present invention, (A) a photocurable composition, (B) a thermosetting resin composition, (C) a photopolymerization initiator, (D) a photoacid generator, and (E) an organic compound. A coating composition containing a solvent, wherein the photocurable composition (A) has an average of two or more radically polymerizable unsaturated groups in one molecule and a number average molecular weight of 250 to 2,000. From at least one compound (A-1) selected from the compound (A-1) inside and a compound having an epoxy group, a compound having an oxetanyl group and a compound having two or more alkoxysilyl groups in one molecule. Therefore, the compound (A-1) and the compound (A-2) have a solid content weight ratio of (A-1) / (A-2) = 0.
Within the range of 5 / 99.5 to 99.5 / 0.5, the photocurable composition (A) and the thermosetting resin composition (B) have a solid content weight ratio of (A) / (B) = 0. In the range of 0.5 / 99.5 to 20/80, the photopolymerization initiator (C) is in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the compound (A-1), and a photoacid generator. (D) is 0.1 to 0.1 parts by weight based on 100 parts by weight of compound (A-2).
The coating composition containing 10 parts by weight is applied to an object to be coated, the coating solution is irradiated with light to thicken the coating solution, and then heated and cured. A method for forming a thermosetting coating film is 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 photocurable composition (A), a thermosetting resin composition (B), a photopolymerization initiator (C), a photoacid generator. A coating composition containing (D) and an organic solvent (E) is used.

Photocurable composition (A) The photocurable composition which is the component (A) of the coating composition used in the present invention has an average of two or more radically polymerizable unsaturated groups in one molecule. And a compound (A-1) having a number average molecular weight in the range of 250 to 2,000, a compound having an epoxy group, a compound having an oxetanyl group, and a compound having two or more alkoxysilyl groups in one molecule. It contains at least one compound (A-2) as an essential component.

The purpose of adding the photocurable composition (A) to the coating composition containing the thermosetting resin composition (B) is to irradiate the coating composition of the coating composition with light to form a coating solution. To increase the viscosity and prevent sagging of the coating liquid. Generally, in the curing by light irradiation, the radical polymerizable unsaturated group-containing compound (A-1) has a fast curing reaction, but has a drawback that the curability of the surface of the coating film is poor due to the influence of oxygen in the air. The compound (A-2) selected from a compound having an epoxy group, a compound having an oxetanyl group, and a compound having two or more alkoxysilyl groups in one molecule is inferior in curability to a radical type, but it is It is characterized in that it can be cured to the surface of the coating film without curing inhibition, and the compound (A-1) is used as the photocurable composition (A).
By using both the compound and the compound (A-2) at the same time,
The curability of the entire system was increased, and the anti-sagging effect could be further improved.

Radical-polymerizable unsaturated group-containing compound (A-
1) The radical-polymerizable unsaturated group-containing compound (A-1) has an average of 2 or more, preferably 3 or more radical-polymerizable unsaturated groups in one molecule from the viewpoint of curability, and has a number-average molecular weight. Is 250 to 2,000, preferably 280 to 1,5
Those within the range of 00 are suitable. Specific examples of the compound (A-1) include, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di ( (Meth) acrylate,
Polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4
-Butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, bisphenol A ethylene oxide modified di (meth) acrylate,
Bisphenol A Propylene oxide modified di (meth)
Acrylate, 2-hydroxy 1-acryloxy 3-methacryloxypropane, tricyclodecane dimethanol di (meth) acrylate, di (meth) acryloyloxyethyl acid phosphate, Kayarad HX-2
20, 620, R-604, MANDA (all manufactured by Nippon Kayaku Co., Ltd.), trimethylolpropane tri (meth) acrylate, trimethylolpropane ethylene oxide-modified tri (meth) acrylate, trimethylolpropane propylene oxide-modified tri ( (Meth) acrylate, glycerin tri (meth) acrylate, glycerin ethylene oxide modified tri (meth) acrylate, glycerin propylene oxide modified tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, isocyanurate ethylene Polymerizable monomers such as oxide-modified triacrylate and dipentaerythritol hexa (meth) acrylate, polyester poly having a molecular weight of 1,700 or less Glycidyl, a polymerizable oligomer obtained by condensation-adding (meth) acrylic acid to a polyol, a polymerizable oligomer obtained by adding (meth) acrylic acid to a compound having a molecular weight of 1,700 or less and having three or more epoxy groups in one molecule, Epoxy group-containing (meth) such as (meth) acrylate
Polymerizable resin obtained by adding (meth) acrylic acid or the like to acrylic resin having a molecular weight of 1,700 or less copolymerized with acrylate, and having a molecular weight of 1,700 copolymerized with an acid-containing (meth) acrylate such as (meth) acrylic acid. Polymerizable resins obtained by adding epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate to the following acrylic resins, polymers of tolylene diisocyanate, polymers of diphenylmethane diisocyanate, polymers of hexamethylene diisocyanate, etc. 2-hydroxyl ethyl (meth) acrylate, hydroxyl propyl (meth) acrylate, butane diol mono (meth) acrylate-containing (meth) acrylate oligomer, glycerin, trimethylolethane, trimethyl Polyols such as propane, pentaerythritol, dipentaerythritol, and sorbitol, isocyanic acid (meth) acrylate, tolylene diisocyanate and isophorone diisocyanate, 2-hydroxyl ethyl (meth) acrylate, hydroxylpropyl (meth) acrylate, butanediol mono (meth) The oligomer etc. which added the compound which has an ethylenically unsaturated group and isocyanate group which added the hydroxyl group containing (meth) acrylates, such as acrylate, can be mentioned.

Here, "(meth) acrylate" means acrylate or methacrylate.

Compound (A-2) The compound (A- which is a raw material of the coating composition used in the present invention.
2) is at least one compound selected from a compound having an epoxy group, a compound having an oxetanyl group, and a compound having two or more alkoxysilyl groups in one molecule.

The compound having an epoxy group in the molecule has an epoxy equivalent of 70 to 1,000, preferably 80 to 1,000.
800 can be preferably used, and specifically, for example, dicyclopentadiene dioxide,
(3,4-epoxycyclohexyl) methyl-3,4-
Epoxy cyclohexanecarboxylate, bis (2,
3-epoxycyclopentyl) ether, bis (3,4)
-Epoxycyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, (3,4-epoxy-6-methylcyclohexyl) methyl-3,4-epoxy-6-methylcyclohexanecarboxylate, Bis (3,4-epoxycyclohexylmethyl) acetal, ethylene glycol bis (3,4-epoxycyclohexyl) ether, ethylene glycol 3,4-epoxycyclohexanecarboxylic acid diester, (3,4-epoxycyclohexyl) methyl alcohol, (3,4-Epoxycyclohexyl) ethyltrimethoxysilane, 3-ethyl-
3- (3,4-epoxycyclohexylmethyl) oxymethyl oxetane, Epolide GT300 (trade name, manufactured by Daicel Chemical Industries, Ltd., trifunctional alicyclic epoxy resin), the following formula

[0015]

[Chemical 1]

An epoxy compound containing an alicyclic epoxy group such as a compound represented by the following; for example, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,4 -Butanediol diglycidyl ether,
Neopentyl glycol diglycidyl ether, 1,6
-Hexanediol diglycidyl ether, glycerin diglycidyl ether, diglycerin tetraglycidyl ether, trimethylolpropane triglycidyl ether, spiroglycol diglycidyl ether, 2,6
-Diglycidyl phenyl ether, sorbitol polyglycidyl ether, triglycidyl isocyanurate,
Epoxy compounds containing aliphatic epoxy groups, such as bisphenol A diglycidyl ether, butadiene dioxide, phthalic acid diglycidyl ester, 3-ethyl-3-glycidyloxymethyl oxetane; for example, vinylcyclohexene dioxide, limonene dioxide and the like. An epoxy compound containing an alicyclic epoxy group and an aliphatic epoxy group; a compound having two or more epoxy groups in one molecule among the above epoxy compounds has 6 carbon atoms.
A fatty acid-modified epoxy compound having an epoxy group and a fatty acid ester group in one molecule obtained by reacting a fatty acid having 3 to 33 (for example, lauric acid, oleic acid, linseed oil fatty acid, etc.) with a part of the epoxy group; glycidyl ( Meta)
(Methyl) glycidyl group-containing polymerizable unsaturated monomers such as acrylate, methylglycidyl (meth) acrylate, and allylglycidyl ether; Alicyclic epoxy group-containing polymerizable unsaturated monomers such as 3,4-epoxycyclohexylmethyl (meth) acrylate Homopolymers or copolymers such as 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, dicyclopentenyloxyethyl (meth)
Acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, an adduct of hydroxyethyl (meth) acrylate and ε-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-pyrrolidone Examples include coalescing. Here, (meth) acrylate means acrylate or methacrylate.

The compound having an oxetanyl group includes
For example, 3-ethyl-3-methoxymethyloxetane,
3-ethyl-3-ethoxymethyl oxetane, 3-ethyl-3-butoxymethyl oxetane, 3-ethyl-3-
Hexyloxymethyl oxetane, 3-methyl-3-hydroxymethyl oxetane, 3-ethyl-3-hydroxymethyl oxetane, 3-ethyl-3-allyloxymethyl oxetane, 3-ethyl-3- (2'-hydroxyethyl) oxy Methyl oxetane, 3-ethyl-3-
(2'-Hydroxy-3'-phenoxypropyl) oxymethyloxetane, 3-ethyl-3- (2'-hydroxy-3'-butoxypropyl) oxymethyloxetane, 3-ethyl-3- (2'-butoxyethyl) ) Oxymethyl oxetane, 3-ethyl-3-benzyloxymethyl oxetane, 3-ethyl-3- (p-tert-butylbenzyloxymethyl) oxetane, the following formula

[0018]

[Chemical 2]

(In the above formula, two R ^a have 1 to 10 carbon atoms.
6 alkyl groups, which may be the same or different.
R ^b is an alkylene group having 1 to 6 carbon atoms, a cycloalkylene group, a phenylene group, a xylylene group, or a carbon atom having 4 to 4 carbon atoms.
30 represents a polyalkyleneoxy group), 3- (acryloyloxymethyl) 3-methyloxetane, 3- (methacryloyloxymethyl) 3-methyloxetane, 3- (acryloyloxymethyl) 3-
Ethyl oxetane, 3- (methacryloyloxymethyl) 3-ethyl oxetane, 3- (acryloyloxymethyl) 3-butyl oxetane, 3- (methacryloyloxymethyl) 3-butyl oxetane, 3- (acryloyloxymethyl) 3-hexyl oxetane And 3-
Examples thereof include homopolymers or copolymers of (methacryloyloxymethyl) 3-hexyloxetane, copolymers of the above-mentioned monomers and the above-mentioned monomers such as styrene, and the like.

Further, a copolymer of an epoxy group-containing (meth) acrylate and an oxetanyl group-containing (meth) acrylate can also be mentioned.

Examples of the compound having two or more alkoxysilyl groups in one molecule include tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane and methyltriethoxy. Alkylalkoxysilanes such as silane, dimethyldimethoxysilane, phenylethoxysilane, diphenyldiethoxysilane, decyltrimethoxysilane; 3-
Glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4
-Epoxycyclohexyl) ethyl group-containing alkylalkoxysilanes such as ethyltrimethoxysilane; vinyltrimethoxysilane, vinyltriethoxysilane,
Ethylenic unsaturated such as 3- (meth) acryloylpropyltrimethoxysilane, 3- (meth) acryloylpropyltriethoxysilane, 3- (meth) acryloylpropylmethyldimethoxysilane, 3- (meth) acryloylpropylmethyldiethoxysilane Group-containing alkoxysilanes; 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropylmethyldimethoxysilane, 3-isocyanatepropylmethyldiethoxysilane, and other alkoxysilanes having an isocyanate group; 3 -Mercaptopropyltrimethoxysilane,
3-chloro-mercaptopropyltrimethoxysilane,
Alkoxysilanes having a mercapto group such as 3-hydroxy-mercaptopropyltrimethoxysilane; vinyltrimethoxysilane, vinyltriethoxysilane,
Ethylenic unsaturated such as 3- (meth) acryloylpropyltrimethoxysilane, 3- (meth) acryloylpropyltriethoxysilane, 3- (meth) acryloylpropylmethyldimethoxysilane, 3- (meth) acryloylpropylmethyldiethoxysilane Group-containing alkoxysilane polymers 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, dicyclopentenyloxyethyl (meth)
Copolymer with a compound having an ethylenically unsaturated group such as acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate; 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, 3-isocyanatepropylmethyl Alkoxysilanes having an isocyanate group such as dimethoxysilane and 3-isocyanatepropylmethyldiethoxysilane, and ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, trimethylolethane, trimethylolpropane And a reaction product with a polyol such as pentaerythritol, dipentaerythritol, and sorbitol. These can be used alone or in combination of two or more.

Further, the compound (A-1) and the compound (A-
The solid content weight ratio with (2) is (A-1) / (A-2) = 0.
5 / 99.5 to 99.5 / 0.5, preferably (A-1)
The range of / (A-2) = 10/90 to 90/10 is suitable from the viewpoint of the balance between thickening due to photocuring and coating smoothness.

Thermosetting Resin Composition (B) The thermosetting resin composition (B) is one that 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 above 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 above 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 carboxyl group-containing unsaturated monomer 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 the polybasic acid mentioned as the raw material for the polyester resin as the carboxyl group-containing compound 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. 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 contained. 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 photocurable composition (A) to the thermosetting resin composition (B) is (A) / (B) = weight solid content ratio.
0.5 / 99.5-20 / 80, preferably 2 / 98-
The range of 15/85 is suitable from the viewpoint of the balance between the thickening by photocuring and the coating performance such as weather resistance and hardness of the final coating.

Photopolymerization Initiator (C) Examples of the photopolymerization initiator (C) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl. Propan-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2
-Morpholino (4-thiomethylphenyl) propane-
1-one, 2-benzyl-2-dimethylamino-1-
(4-morpholinophenyl) -butanone, 2,4,6-
Trimethylbenzoylphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, benzophenone, methyl o-benzoylbenzoate, hydroxybenzophenone, 2
-Isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4
-Dichlorothioxanthone, 2,4,6-tris (trichloromethyl) -S-triazine, 2-methyl-4,6
-Bis (trichloro) -S-triazine, 2- (4-methoxyphenyl) -4,6-bis (trichloromethyl)
-S-triazine and the like can be mentioned.

These photopolymerization initiators can be used alone or in combination of two or more, and the compounding amount thereof is 100 parts by weight of the radical-polymerizable unsaturated group-containing compound (A-1). C) is 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight in terms of photocurability.

Further, in order to accelerate the photopolymerization reaction by the photoradical polymerization initiator, a photosensitization accelerator may be used in combination with the photopolymerization initiator. Examples of the photosensitizer that can be used in combination include triethylamine, triethanolamine, methyldiethanolamine, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and 4
-Isoamyl dimethylaminobenzoate, benzoic acid (2-
Dimethylamino) ethyl, Michler's ketone, 4,4'-
Tertiary amines such as diethylaminobenzophenone, alkylphosphine such as triphenylphosphine, β-
Examples thereof include thioether type compounds such as thiodiglycol. These photosensitizers can be used alone or in combination of two or more, and the amount thereof is 0.1 to 5 parts by weight with respect to 100 parts by weight of the radically polymerizable unsaturated group-containing compound (A-1). Within the range of parts is preferable.

Photoacid Generator (D) The photoacid generator (D) is a photopolymerization initiator which generates an acid upon irradiation with light. As the photo-acid generator (D), 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

[0042]

[Chemical 3]

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

[0044]

[Chemical 4]

(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)

[0046]

[Chemical 5]

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

[0048]

[Chemical 6]

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

[0050]

[Chemical 7]

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

[0052]

[Chemical 8]

[0053]

[Chemical 9]

(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)

[0055]

[Chemical 10]

[0056]

[Chemical 11]

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

[0058]

[Chemical 12]

(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).

[0060]

[Chemical 13]

(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)

[0062]

[Chemical 14]

[0063]

[Chemical 15]

Commercially available products of the above-mentioned 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)
And so on.

The above photo-acid generator (D) may be used alone or in a mixture of 2
These can be used in combination of two or more kinds, and the compounding amount thereof is 0.1 to 10 parts by weight, preferably 0.3 to 7 parts by weight with respect to 100 parts by weight of the compound (A-2). Suitable from the viewpoint of curability.

Organic Solvent (E) As the organic solvent (E), the above-mentioned photocurable composition (A) is used.
Also, any inert organic solvent which does not substantially react with the thermosetting resin composition (B) can be used without particular limitation. 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-based solvents; ether-based solvents such as dioxane, ethylene glycol diethyl ether, ethylene glycol dibutyl ether; and ketone-based solvents such as acetone, methyl ethyl ketone, and 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 and 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.

Particularly, for those which easily cause sagging during setting, it is preferable to irradiate light as early as possible after coating, but in general, there are many cases where sagging occurs at the time of heating and drying, and 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.

[0073]

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 of Radical Polymerizable Unsaturated Group-Containing Compound Production Example 1 A reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and an air blowing device was charged with 182 parts of xylene.
Denacol EX-612 (manufactured by Nagase Chemical Industry Co., Ltd., sorbitol polyglycidyl ether) 510 parts, acrylic acid 216 parts, hydroquinone monomethyl ether 0.4 parts and tetrabutylammonium bromide 3 parts were charged, and while blowing air into the reaction vessel, 115 The temperature was raised to ℃ and kept at that temperature for 5 hours. After confirming that all of the added acrylic acid had reacted, it was cooled and the solid content of the resin was 80%.
A radically polymerizable unsaturated group-containing oligomer solution of was obtained.
The number average molecular weight of the oligomer is about 970, and it has an average of about 3 radically polymerizable unsaturated groups in one molecule.

Production Example 2 888 parts of isophorone diisocyanate, 464 parts of 2-hydroxyethyl acrylate and 0.7 parts of hydroquinone monomethyl ether were placed in a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser and an air blowing device.
80 parts while blowing air into the reaction vessel.
After the temperature was raised to ℃ and kept at that temperature for 5 hours and it was confirmed that the added 2-hydroxyethyl acrylate was substantially completely reacted, 136 parts of pentaerythritol, 372 parts of butyl acetate and 0.2 parts of dibutyltin dilaurate were added. Was further added and held at 80 ° C., and after confirming that substantially all of isophorone diisocyanate had reacted, the mixture was cooled to obtain a radical-polymerizable unsaturated group-containing resin solution having a resin solid content of 80%. The number average molecular weight of the resin is about 1,500, and it has about 4 radically polymerizable unsaturated groups in one molecule.

Having an epoxy group and / or an oxetanyl group
Production Example 3 thermometer compounds, thermostat, stirrer, the reaction vessel equipped with a reflux condenser and dropping device was charged with butyl acetate 480 parts, followed by heating to 130 ° C. while blowing nitrogen gas, the temperature While maintaining the above, a mixture liquid of the following monomer and initiator was dropped from the dropping device over 3 hours.

[0077] After completion of dropping, the mixture was aged at 130 ° C. for 1 hour to obtain an epoxy group-containing copolymer solution having a solid content of 70%. Copolymer GPC
The number average molecular weight measured by (gel permeation chromatography) was 3,000, and the number of epoxy groups was 5 on average.

Production Example 4 480 parts of butyl acetate were placed in 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, and then the temperature was raised. While maintaining the temperature, a mixture liquid of the following monomer and initiator was dropped from the dropping device over 3 hours.

[0079] After completion of dropping, the mixture was aged at 130 ° C. for 1 hour to obtain an oxetanyl group-containing copolymer solution having a solid content of 70%. Copolymer G
The number average molecular weight measured by PC (gel permeation chromatography) was 3,000, and the number of oxetanyl groups was 5 on average.

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 heated to 130 ° C. while blowing nitrogen gas, and then the temperature was raised. While maintaining the temperature, a mixture liquid of the following monomer and initiator was dropped from the dropping device over 3 hours.

[0081] After completion of dropping, the mixture was aged at 130 ° C. for 1 hour to obtain an epoxy group- and oxetanyl group-containing copolymer solution having a solid content of 70%. The number average molecular weight of the copolymer measured by GPC (gel permeation chromatography) is 3,000, and the average number of epoxy groups is 3
And the number of oxetanyl groups was 2 on average.

Production of alkoxysilyl group-containing compound 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. After warming, while maintaining the temperature, a mixed solution of the following monomer and initiator was added dropwise from the dropping device over 3 hours.

[0083] 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 3,000, and the number of alkoxysilyl groups was 11 on average.

Production Example 7 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 528
And the average number of alkoxysilyl groups was 6.

Production of Thermosetting Resin Production Example 8 480 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.

[0086] 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 3,000, and the hydroxyl value was 108.

Production Example 9 296 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 1,000 and the hydroxyl value was 112.

Production Example 10 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.

[0089] 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 3,000, and the acid value was 104.

Production Example 11 480 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 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.

[0091] 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 3,000, and the epoxy equivalent was 530.

Preparation of Paint Preparation Example 1 2.5 parts of radical-polymerizable unsaturated group-containing oligomer solution of Preparation Example 1 and epoxy group-containing copolymer solution of Preparation Example 3.
5 parts, (3,4-epoxycyclohexyl) methyl-
3,4-epoxycyclohexanecarboxylate 2
Parts, 100 parts of the hydroxyl group-containing copolymer solution of Production Example 8 and 23 parts of Cymel 235 (methyl / butylated melamine resin manufactured by Mitsui Cytec Co., Ltd.) were stirred and mixed, and then Irgacure 81
9 (manufactured by Ciba Specialty Chemicals, photo radical polymerization initiator) and 0.1 part of CI-2855 (manufactured by Nippon Soda Co., Ltd., photo acid generator) were added and dissolved, and then an ultraviolet absorber. As an additive, 0.6 parts of TINUVIN 400 (manufactured by Ciba Specialty Chemicals) and 0.3 parts of TINUVIN 144 (manufactured by Ciba Specialty Chemicals).
25 parts in a Ford cup # 4 (20 ° C), which is an appropriate viscosity for spray painting.
A paint T1 was prepared according to the second. The solid content in the coating material T1 was 65%.

Preparation Example 2 Radical-polymerizable unsaturated group-containing resin solution 2.0 of Preparation Example 2
Part, pentaerythritol tetraacrylate 2.5
Part, oxetanyl group-containing copolymer solution 2.0 of Production Example 4
Part, (3,4-epoxycyclohexyl) methyl-3,
After stirring and mixing 3 parts of 4-epoxycyclohexanecarboxylate, 100 parts of the hydroxyl group-containing copolymer solution of Production 8, and 32 parts of Sumidule N-75 (solid content 75%, Sumitomo Bayer Urethane Co., polyisocyanate compound) with stirring,
Irgacure 819 (Ciba Specialty Chemicals, radical photopolymerization initiator) 0.2 parts and PI-20
After adding 0.2 parts of 74 (manufactured by Roger Co., Ltd., a photo-acid generator) and dissolving, 0.6 parts of TINUVIN 400 and 0.3 parts of TINUVIN 144 as an additive such as an ultraviolet absorber are further added and dissolved. Then, it was diluted with xylene, and was adjusted to 25 seconds with a Ford cup # 4 (20 ° C.), which is an appropriate viscosity for spray coating, to prepare a coating material T2. The solid content in the coating material T2 was 67%.

Preparation Example 3 5 parts of pentaerythritol tetraacrylate, (3,
4-Epoxycyclohexyl) methyl-3,4-epoxycyclohexanecarboxylate 5 parts, 80 parts hydroxyl group-containing polyester resin solution of Preparation Example 9 and Cymel 23
After stirring and mixing 26 parts of 5 (Mitsui Cytec, methyl / butylated melamine resin), Irgacure 184 (Ciba Specialty Chemicals, photo radical polymerization initiator)
0.1 part and PI-2074 (manufactured by Roger Co., a photo-acid generator) were added and dissolved, and then 0.6 part of tinuvin 400 and tinuvin 144 were further added as an additive such as an ultraviolet absorber. 0.3 part was added and dissolved, diluted with xylene, and the paint T3 was prepared by adjusting the Ford cup # 4 (20 ° C.), which has an appropriate viscosity for spray coating, for 25 seconds.
The solid content in the coating material T3 was 75%.

Preparation Example 4 3 parts of dipentaerythritol hexaacrylate, 3 parts of the epoxy group- and oxetanyl group-containing copolymer solution of Production Example 5, and the hydroxyl group-containing polyester resin solution 84 of Production Example 9
Parts and Sumijour N-75 (solid content 75%, manufactured by Sumitomo Bayer Urethane Co., polyisocyanate compound) 37 parts by stirring and mixing, and then 0.1 part of Irgacure 184 (photo radical polymerization initiator manufactured by Ciba Specialty Chemicals) and After 0.1 part of Cylacure UVI-6990 (manufactured by Union Carbide, a photo-acid generator) was added and dissolved, Tinuvin 400 was further added as an additive such as a UV absorber at a concentration of 0.
6 parts and 0.3 parts of TINUVIN 144 were added and dissolved, diluted with xylene, and adjusted to 25 seconds with Ford cup # 4 (20 ° C.), which has an appropriate viscosity for spray coating, to prepare a coating T4. The solid content in the coating T4 was 74%.

Preparation Example 5 Pentaerythritol tetraacrylate 3 parts, (3,
4-Epoxycyclohexyl) methyl-3,4-epoxycyclohexanecarboxylate 7 parts, 64 parts of the carboxyl group-containing copolymer solution of Preparation 10 and Preparation 11
After stirring and mixing 64 parts of the epoxy group-containing copolymer solution described above, 0.05 parts of Irgacure 819 (photo radical polymerization initiator manufactured by Ciba Specialty Chemicals) and CI-
0.3 parts of 2855 (manufactured by Nippon Soda Co., Ltd., a photo-acid generator) were added and dissolved, and then 0.6 parts of tinuvin 400 and 0.3 parts of tinuvin 144 were further added as additives such as an ultraviolet absorber. It was dissolved, diluted with xylene, and adjusted to 25 seconds with Ford cup # 4 (20 ° C.), which is an appropriate viscosity for spray coating, to prepare a coating T5. The solid content in the coating material T5 was 70%.

Preparation Example 6 2.5 parts of radical-polymerizable unsaturated group-containing oligomer solution of Preparation Example 1, 2.5 parts of alkoxysilyl group-containing copolymer solution of Preparation Example 6, 2 parts of dimethyldimethoxysilane, Preparation Example 8 100 parts of a hydroxyl group-containing copolymer solution and Cymel 23
After stirring and mixing 23 parts of 5 (Mitsui Cytec, methyl / butylated melamine resin), Irgacure 819 (Ciba Specialty Chemicals, photo radical polymerization initiator)
And 0.1 part of CI-2855 (manufactured by Nippon Soda Co., Ltd., photo-acid generator) were added and dissolved, and then TINUVIN 400 (manufactured by Ciba Specialty Chemicals Inc.) as an additive such as an ultraviolet absorber. ) 0.6 parts and tinuvin 144
0.3 part (manufactured by Ciba Specialty Chemicals Co., Ltd.) was added and dissolved, diluted with xylene, and adjusted to 25 seconds with Ford cup # 4 (20 ° C.), which is an appropriate viscosity for spray coating, to prepare a coating T6. The solid content in the coating T6 was 65%.

Preparation Example 7 Radical-polymerizable unsaturated group-containing resin solution 2.0 of Preparation Example 2
Part, pentaerythritol tetraacrylate 2.5
Parts, 1.5 parts of alkoxysilyl group-containing oligomer solution of Production Example 7, 2.0 parts of (3,4-epoxycyclohexyl) methyl-3,4-epoxycyclohexanecarboxylate, hydroxyl group-containing copolymer solution of Production Example 8 After stirring and mixing 100 parts and 32 parts of Sumidule N-75 (solid content 75%, manufactured by Sumitomo Bayer Urethane Co., polyisocyanate compound), 0.2 parts of Irgacure 819 (photo radical polymerization initiator manufactured by Ciba Specialty Chemicals). And PI-2074 (manufactured by Roger Co., Ltd., a photo-acid generator) were added and dissolved, and then 0.6 parts of tinuvin 400 and tinuvin 14 were further added as an additive such as an ultraviolet absorber.
0.3 parts of 4 was added and dissolved, diluted with xylene, and the suitable viscosity for spray coating was Ford Cup # 4 (20
The paint T7 was prepared by adjusting the temperature to 25 ° C. for 25 seconds. The solid content in the coating material T7 was 67%.

Preparation Example 8 3 parts of dipentaerythritol hexaacrylate, 4 parts of methyltriethoxysilane, 84 parts of the hydroxyl group-containing polyester resin solution of Preparation Example 9 and Sumidule N-75 (solid content 75%, manufactured by Sumitomo Bayer Urethane Co., poly (Isocyanate compound) 37 parts by stirring and mixing, and then Irgacure 18
4 (manufactured by Ciba Specialty Chemicals, photo radical polymerization initiator) 0.1 part and Syracure UVI-699
0 (manufactured by Union Carbide, photo-acid generator) was added to 0.1 parts and dissolved, and then 0.6 parts of tinuvin 400 and 0.3 parts of tinuvin 144 as additives such as an ultraviolet absorber.
25 parts in a Ford cup # 4 (20 ° C), which is an appropriate viscosity for spray painting.
A paint T8 was prepared according to the second. The solid content in the coating material T8 was 74%.

Preparation Example 9 (for comparison) 100 parts of the hydroxyl group-containing copolymer solution of Preparation Example 8 and 23 parts of Cymel 235 (methyl / butylated melamine resin manufactured by Mitsui Cytec Co., Ltd.) were stirred and mixed, and then an ultraviolet absorber or the like was added. As an agent, 0.6 parts of TINUVIN 400 and 0.3 part of TINUVIN 144 were added and dissolved, diluted with xylene, and the suitable viscosity for spray coating was Ford Cup # 4 (20 ° C).
Then, the paint T9 was prepared in 25 seconds. The solid content in the coating T9 was 67%.

Preparation Example 10 (for comparison) Mizukasil P526 (manufactured by Mizusawa Chemical Co., Ltd.) as an anti-sagging agent
5 parts of hydroxyl group-containing polyester resin solution 8 of Production Example 9
After stirring and mixing 4 parts and 37 parts of Sumidule N-75 (polyisocyanate manufactured by Sumitomo Bayer Urethane Co., Ltd. with a solid content of 75%), 0.6 parts of tinuvin 400 and 0.3 parts of tinuvin 144 as additives such as an ultraviolet absorber. Part of the mixture was dissolved, diluted with xylene, and adjusted to 25 seconds with a Ford cup # 4 (20 ° C.), which has an appropriate viscosity for spray coating, to prepare a coating T10. The solid content of the paint T10 is 45
%Met.

Preparation Example 11 (for comparison) Mizukasil P526 (manufactured by Mizusawa Chemical Co., Ltd.) as an anti-sagging agent
5 parts of hydroxyl group-containing polyester resin solution 8 of Production Example 9
After stirring and mixing 4 parts and 37 parts of Sumidule N-75 (polyisocyanate compound manufactured by Sumitomo Bayer Urethane Co., Ltd. with a solid content of 75%), Tinuvin 4 as an additive such as an ultraviolet absorber.
A coating material T11 having a solid content of 60% was prepared by adding 0.6 part of 00 and 0.3 part of tinuvin 144 to dissolve and dilute. The viscosity of this paint T11 was 100 seconds in Ford cup # 4 (20 ° C.).

Preparation of test material Thickness 0.8 mm, 25 cm that has been subjected to zinc phosphate chemical conversion treatment
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.

Formation of thermosetting coatings Examples 1 to 8 The above test materials were placed vertically, and the coatings prepared in the above Preparation Examples 1 to 5 were air-sprayed on the upper part of 15 cm so that the cured coatings had a thickness of 40 μm. Painted on, then immediately 120W
/ Cm 2 with a metal halide lamp of 1000 mJ / cm ²
After irradiation with ultraviolet rays, the coated plate was placed vertically in a drying oven with the coated part facing upward, and heated at 140 ° C. for 30 minutes to cure the coating film, thereby forming a top coating film.

Comparative Examples 1 to 3 The coated plates coated with the coating materials prepared in Comparative Preparation Examples 9 to 11 under the same conditions as those of the above-described Examples were not irradiated with ultraviolet rays, and the coated portions of the coated plates were placed in the drying oven. Place it vertically so that it becomes 1
The coating film was cured by heating at 40 ° C. for 30 minutes to form a top coating film.

The solid content of each coating used in the above test, the evaluation of sag, the evaluation of smoothness and the evaluation of curability were carried out by the following methods. 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 heated at 130 ° C. for 3 hours, after which 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: The coated surface was wiped 50 times back and forth with gauze containing xylene, and then the coated surface was observed. The evaluation criteria are as follows.

◯: No change on the coated surface and good, Δ: Scratch was observed on the coated surface and the curability was poor, ×: The coating surface was dissolved in xylene and the curability was significantly poor.

Coating Viscosity Before and After Light Irradiation In order to confirm the change in viscosity of the coating liquid due to light irradiation, the coating composition prepared in the above Preparation Examples 1 to 11 was air-sprayed so that the cured coating film had a thickness of 40 μm. Each sample is coated with 2 sheets, and one sheet is immediately irradiated with 1000 mJ / cm ^{2 of} ultraviolet rays. Then, the non-irradiated coating film and the irradiated coating film are scraped off from the glass plate. Industrial RE80 type rotation speed: 1 RPM). The results are shown in Table 2.

[0114]

[Table 1]

[0115]

[Table 2]

[0116]

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    F term (reference) 4D075 BB26Z BB43Y BB99Y CA48                       DA06 DA23 DB02 DC12 EA07                       EA19 EA21 EB22 EB33 EB37                       EB38 EB42 EB52 EB56 EC37                       EC54

Claims (3)

[Claims] 1. A photocurable composition (A), a thermosetting resin composition (B), a photopolymerization initiator (C), a photoacid generator (D),
And (E) a coating composition containing an organic solvent, wherein the photocurable composition (A) has an average of two or more radically polymerizable unsaturated groups in one molecule and a number average molecular weight of 250 to
Compound (A-1) in the range of 2,000 and at least one compound selected from a compound having an epoxy group, a compound having an oxetanyl group and a compound having two or more alkoxysilyl groups in one molecule ( A-2), wherein the compound (A-1) and the compound (A-2) have a solid content weight ratio of (A-1) / (A-2) = 0.5 / 99.5 to 99.5.
Within the range of 0.5 / 0.5, the photocurable composition (A) and the thermosetting resin composition (B) have a solid content weight ratio of (A) / (B) = 0.
Within the range of 5 / 99.5 to 20/80, the photopolymerization initiator (C) is 0.1 based on 100 parts by weight of the compound (A-1).
Within the range of 10 to 10 parts by weight, and the photoacid generator (D) is a compound
-2) After coating the coating composition, which is contained in the range of 0.1 to 10 parts by weight based on 100 parts by weight, on the article to be coated,
A method for forming a thermosetting coating film, which comprises irradiating a coating solution with light to increase the viscosity of the coating solution, followed by heating and curing. 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.