JPH11300272A - Method for forming coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a coating film excellent in the smoothness of a coating surface by a method in which a substrate is coated with a liquid coating composition containing a thermosetting resin composition and an active energy ray curable resin composition, the coating surface is irradiated with active energy rays for preliminary curing, and the coating film is heated to be cured completely. SOLUTION: In a method for forming a coating film in which the sagging of an applied coating in the vertical part of a surface to be coated is controlled, after the surface being coated with a liquid coating composition containing a thermosetting resin composition and an active energy ray curable resin composition, the coating surface is radiated with active energy rays for preliminary curing, and the coating film is heated to be cured completely. As the thermosetting resin composition, a composition comprising a substrate resin such as an acrylic resin having crosslinkable functional groups such as hydroxyl groups and a crosslinking agent such as a melamine resin which can react with these functional groups is used. Besides, a composition containing a polymerizable unsaturated compound and others is used as the active energy ray curable resin composition.

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 coating film, and more particularly to a method for forming a coating film having excellent smoothness on a coating surface (particularly, a vertical portion) without deteriorating the chemical and physical performance of the coating film. About the method.

[0002]

2. Description of the Related Art A thermosetting coating material controls the fluidity of the coating material to form a smooth coating surface, and hardly causes dripping of the coating material in a vertical portion of the coating surface. For this purpose, a flow control agent is incorporated. Various fluid regulators are known, for example, inorganic additives such as Erosil and Benton, polyamide compounds such as DISPARON (trade name, manufactured by Kusumoto Kasei Co., Ltd.), diisocyanate compounds and A diurea compound, a gelled polymer fine particle, and the like obtained by a reaction with a secondary amine are generally used.

[0003] The addition of these flow control agents affects the rheological properties of the coating composition, and as a result, improves the prevention of sagging of the coating film in the vertical portion and the pattern control of the metallic pigment. However, on the other hand, there are defects that the finished appearance such as gloss of the coated surface, the interlayer adhesion when further coating is applied, and the water resistance of the coating film are reduced.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate these defects in a thermosetting paint, and to provide an active energy ray-curable resin composition without adding a flow control agent. Active energy in the paint film
It has been found that the object can be achieved by preliminarily curing the film by irradiating the film and then heating the film to completely cure the film, thereby completing the present invention.

That is, according to the present invention, a liquid coating composition containing a thermosetting resin composition and an active energy ray-curable resin composition is applied to an object to be coated, and the coated surface is irradiated with active energy rays. After pre-curing, and heating to completely cure the coated film.

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

[0007] The liquid coating composition used in the present invention (hereinafter referred to as "the liquid coating composition")
The present composition) contains a thermosetting resin composition (a) and an active energy ray-curable resin composition (b), and these are mixed with a solvent such as an organic solvent.

The thermosetting resin composition (a) is a resin composition which can be cured three-dimensionally by a cross-linking reaction upon heating, for example, an acrylic resin having a crosslinkable functional group such as a hydroxyl group,
Vinyl resins, polyester resins, base resins such as alkyd resins, and melamine resins that can react with these functional groups,
A composition comprising a crosslinking agent such as a block polyisocyanate compound is exemplified.

Examples of the acrylic resin or vinyl resin having a hydroxyl group include a polymer obtained by polymerizing a hydroxyl group-containing monomer with another monomer.

The hydroxyl group-containing monomer is a compound having at least one hydroxyl group and at least one polymerizable unsaturated bond in one molecule, for example, hydroxyethyl (meth) acrylic acid.
, Hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate and the like having 2 to 20 carbon atoms
And a monoesterified product of (meth) acrylic acid and the like. The other monomer is a compound other than the hydroxyl group-containing monomer and has at least one polymerizable unsaturated bond in one molecule, and includes the following monomers.

Acrylic monomer: a monoester of (meth) acrylic acid and a monovalent alcohol having 1 to 22 carbon atoms, such as methyl (meth) acrylate and ethyl (meth) acrylate , Propyl (meth) acryle
Butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like. Alkoxy ester-based monomer: (meth) acrylic acid and an alkoxy ester having 2 to 18 carbon atoms, for example, methoxybutyl (meth) acrylate,
Methoxyethyl (meth) acrylate and the like. Aminoacrylic monomer: N, N-dimethylaminoethyl (meth)
Acrylate, N, N-diethylaminoethyl (meth)
Acrylate, Nt-butylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth)
Acrylate etc. Acrylamide monomer: (meth)
Acrylamide, N-methyl (meth) acrylamide,
N-ethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-dimethyl (meth) acrylamide and the like. Carboxyl group-containing monomer: a compound having at least one carboxyl group and at least one polymerizable unsaturated bond in one molecule, for example, monocarboxylic acids such as acrylic acid and methacrylic acid, maleic acid, itaconic acid,
Fumaric acid, mesaconic acid, anhydrides thereof, dicarboxylic acids such as half esterification, and modified products thereof;
Glycidyl group-containing monomers: glycidyl (meth) acrylate and the like. Others: styrene, α-methylstyrene, vinyl toluene, acrylonitrile, vinyl acetate, vinyl chloride, etc.

The polymerization reaction of the hydroxyl group-containing monomer with other monomers can be carried out by a known method, and the hydroxyl value of the obtained hydroxyl group-containing acrylic resin is 50 to 150 mg KOH.
/ G, especially 65-120 mgKOH / g, acid value is 0-5
0 mgKOH / g, especially 1-20 mgKOH / g, number average molecular weight of about 2000-100,000, especially 3000-
A range of 50,000 is suitable.

The polyester resin and alkyd resin having a hydroxyl group are usually produced by subjecting a polybasic acid and a polyhydric alcohol to an esterification reaction.
It is preferable that one molecule has two or more hydroxyl groups.

The polybasic acid is a compound having two or more carboxyl groups in one molecule, for example, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic acid, Examples thereof include hexahydrophthalic acid, heptic acid, maleic acid, fumaric acid, itaconic acid, trimellitic acid and anhydrides thereof. The polyhydric alcohol is a compound having two or more hydroxyl groups in one molecule. Examples thereof include ethylene glycol, propylene glycol, and butylene glycol.
Hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, glycerin, trimethylolethane,
And trimethylolpropane.

The hydroxyl group-containing polyester resin and alkyd resin can be prepared by reacting such a polybasic acid with a polyhydric alcohol in excess of a hydroxyl group according to a known esterification method. 5
0-150 mgKOH / g, especially 65-120 mgKO
H / g, acid value is 0 to 50 mgKOH / g, especially 1 to 20
mgKOH / g, number average molecular weight is about 2000-2000
Resins in the range of 0, especially 5000-13000 are suitable.

As the polyester resin and alkyd resin, linseed oil fatty acid, coconut oil fatty acid, safflower oil fatty acid, soybean oil fatty acid, sesame oil fatty acid, eno oil fatty acid, hemp oil fatty acid, trol oil fatty acid, dehydrated castor oil Those modified with (semi) dry oil fatty acids such as fatty acids can also be used. The modification amount of these fatty acids is 30 in oil length.
% Is suitable. These resins may contain a polymerizable unsaturated bond.

Examples of the cross-linking agent include melamine resins and block polyisocyanate compounds capable of cross-linking with these hydroxyl group-containing resins.

As the melamine resin, part or all of the methylol group of methylolated melamine has 1 to 8 carbon atoms.
A partially or fully etherified melamine resin etherified with a monovalent alcohol of the formula:
A pentanuclear compound having a molecular weight of 300 to 2,000 is preferable. Also included are melamine resins containing imino groups.

The block polyisocyanate compound is a polyisocyanate compound in which all the isocyanate groups of the polyisocyanate compound are blocked with a blocking agent. When heated to a predetermined temperature, the blocking agent is dissociated and the isocyanate group is regenerated. To form a crosslinking reaction with the hydroxyl group-containing resin.

The polyisocyanate compound is a compound having two or more isocyanate groups in one molecule, for example, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene. Aromatic diisocyanate such as diisocyanate; aliphatic diisocyanate such as tetramethylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate and lysine diisocyanate; Methylene bis (cyclohexyl isocyanate), isophorone diisocyanate, methylcyclohexane diisocyanate
Cycloaliphatic diisocyanates such as cyclohexane diisocyanate and cyclopentane diisocyanate;
A biuret type adduct, an isocyanuric ring type adduct of the polyisocyanate; and a free isocyanate obtained by reacting the polyisocyanate with a low molecular weight or high molecular weight polyol in excess of an isocyanate group. Group-containing prepolymers. Blocking agents include phenols, oximes, lactams, active methylenes, alcohols, acid amides, imides, amines, imidazoles, ureas, carbamic acids, imines, mercaptans Are preferred. The molecular weight of the block polyisocyanate is preferably from 200 to 10,000.

The composition ratio of the base resin and the crosslinking agent can be arbitrarily selected according to the purpose. For example, based on the total weight of both components, the base resin is 50 to 90% and the crosslinking agent is 50%. A range of 10% to 10% is suitable.

Active energy ray-curable resin composition (b)
Is a composition that can be cured by a cross-linking reaction by irradiating active energy rays such as ultraviolet rays or electron beams. Specifically, a polymerizable unsaturated compound, a photopolymerization initiator, and a thermal polymerization initiator are used. Compositions.

The polymerizable unsaturated compound is a compound having one or more polymerizable unsaturated bonds in one molecule, and examples thereof include the following compounds.

A) Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate
(Meth) acrylic acid such as butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate And carbon number 1-22
Monoesterified with monohydric alcohol.

B) Mono (or di) of (meth) acrylic acid with glycol having 2 to 20 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol and the like.
Esterified products.

C) maleic acid, itaconic acid, fumaric acid,
Mesaconic acids and their dicarboxylic acids such as anhydrides and half-esterified products or modified products thereof.

D) (meth) acrylic acid with 2 to 18 carbon atoms
Alkoxy esters of

E) N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, Nt-butylaminoethyl (meth) acrylate, N, N- Amino acrylic monomers such as dimethylaminopropyl (meth) acrylate.

F) Acrylamide monomers such as (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-butyl (meth) acrylamide and N-dimethyl (meth) acrylamide.

G) Glycidyl group-containing monomers such as glycidyl (meth) acrylate.

H) Styrene, α-methylstyrene, vinyltoluene, acrylonitrile, vinyl acetate, vinyl chloride and the like.

[0032] _{i) Ph-O- (C 2} H 4 0) n-0CH
C = CH ₂ (where Ph is a phenol group and has 15 carbon atoms)
Phenol-ethylene oxide-modified acrylate, 2-ethylhexylcarbitol acrylate represented by the following formula (including those having the following alkyl groups, n is an integer of 1 to 6):
N-vinylpyrrolidone, bisphenol A ethylene oxide-modified diacrylate, isocyanuric acid ethylene oxide-modified diacrylate, tripropylene glycol diacrylate, pentaerythritol diacrylate monostearate, tetraethylene glycol diacrylate -Polyethylene glycol diacrylate
Propylene glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane propylene oxide modified triacrylate, isocyanuric acid ethylene oxide modified triacrylate, trimethylol Propane ethylene oxide modified triacryle
Oligomer, ω-carboxy-polycaprolactone monoacrylate having 2 moles of acrylic acid added to both hydroxyl groups of polyurethane, dipentaerythritol penta and hexaacrylate, pentaerythritol tetraacrylate, and polyurethane Monohydroxyethyl phthalate, acrylic acid dimer, 2-hydroxy-3
-Phenoxypropyl acrylate, an oligomer obtained by adding 2 mol or more of acrylic acid to a terminal hydroxyl group of a polyester, and the like. The number average molecular weight of the polymerizable unsaturated compound is 50
-3000, especially 100-2000 is preferred.

The photopolymerization initiator is used for accelerating the crosslinking (polymerization) reaction of the polymerizable unsaturated compound by irradiation with an active energy ray. Examples thereof include benzoin, benzoin methyl ether and benzoin ethyl ether. -Tell, 2-
Methyl benzoin, benzyl, benzyl dimethyl ket
, Diphenyl sulfide, tetramethylthiuram monosulfide, diacetyl, eosin, thionine, Michler's ketone, anthracene, anthraquinone, acetophenone, α-hydroxyisobutylphenone, p-isopropyl α-hydroxyisobutylphenone, α-α′-dichloro-4-phenoxy Acetophenone, 1-hydroxy-1-cyclohexylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, methylbenzoylformate, 2-methyl-1- [4- (methylthio) phenyl] .2-morpholino-propene, thioxanthone, Benzophenone, 2,2-dimethoxy-1,
2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 1-hydroxy-cyclohexyl-phenyl-ketone, benzophenone,
-Methyl-1- [4- (methylthio) phenyl] -2-
Monforinopropanone 1,2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone 1,2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,4 , 6-Trimethylbenzoyldiphenyl-phosphine oxide, 1- [4- (2
-Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1one, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyr-yl) titanium), 2 -Hydroxy-2-methyl-1-phenylpropan-1-one, bisacylphosphine oxide, (η ⁵ -2,4-cyclopentadien-1-yl) [(1,2,3,4,5,6 −η) −
(1-methylethyl) benzene] -iron (1 +)-
Hexafluorophosphate (1-) and the like.

The ratio of the photopolymerization initiator is 0.1 to 10 parts by weight, especially 0.1 to 100 parts by weight, per 100 parts by weight of the polymerizable unsaturated compound.
5 to 5 parts by weight are suitable.

The thermal polymerization initiator promotes a crosslinking (polymerization) reaction of a polymerizable unsaturated compound contained in a portion not irradiated with active energy rays or in a coating film with insufficient irradiation by heating. For example, benzoyl peroxide, di-t-butyl hydroperoxide, t-butyl hydroperoxide, cumylperoxide, cumene hydroperoxide, diisopropylbenzane hydroperoxide, t-butylperoxyoxybenzoate,
Lauryl peroxide, acetyl peroxide, t
Peroxides such as -butylperoxy-2-ethylhexanoate; and azo compounds such as α · α'-azobisisobutylnitrile, azobisdimethylvaleronitrile, and azobiscyclohexanecarbonitrile.

The amount of the thermal polymerization initiator to be used is suitably 0.1 to 10 parts by weight, particularly 0.5 to 5 parts by weight, per 100 parts by weight of the polymerizable unsaturated compound.

The present composition comprises the thermosetting resin composition (a) and the active energy ray-curable resin composition (b).
The composition ratio of these components is 20 to 95% based on the total weight of both components,
Especially 50 to 90%, composition (b) is 80 to 5%, especially 5
A range of 0 to 10% is suitable.

Further, as an organic solvent for mixing the two compositions, a hydrocarbon solvent, an ester solvent, an ether solvent, an alcohol solvent, a ketone solvent and the like can be used.

The present composition comprises the thermosetting resin composition (a) and the active energy ray-curable resin composition (b) described above.
Can be prepared by mixing and dispersing in an organic solvent, and a pigment, a coating surface adjuster, an antioxidant, a flow adjuster, a pigment dispersant, and the like can be appropriately compounded. When an alkanolamine such as triethanolamine, diethanolamine or monoethanolamine is added in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the polymerizable unsaturated compound of the composition (b), the curability of the coating film is reduced. improves.

Examples of pigments include titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chrome ero, chromium oxide, prussian bull, cobalt bull, azo pigment, phthalocyanine pigment,
Color pigments such as quinacridone pigments, isoindoline pigments, threne-based pigments and perylene pigments; extender pigments such as talc, clay, kaolin, barita, barium sulfate, barium carbonate, calcium carbonate, silica, and alumina white;
Examples include, but are not limited to, metallic pigments such as aluminum powder, mica powder, and mica powder coated with titanium oxide.

The substrate to which the method of the present invention is applied is not particularly limited, but a metal or plastic outer body portion of an automobile body, household electric appliance, office equipment or the like is particularly suitable.

The composition can be applied to these substrates as an intermediate coating and / or a top coating.
Among them, it is particularly preferable to use as a top coat such as a solid color paint, a metallic paint and a clear paint. Specifically, the viscosity of the composition is 15 to 25.
Sec / ford cup # 4/20 ° C, solid content 40
~ 95% by weight, electrostatic coating, airless spray,
By air spray, etc., the cured coating film is 10 to 60 μm,
In particular, it is preferable to apply a thickness of 15 to 40 μm.

The method of the present invention comprises the step of drying the thus coated coating film of the present composition, if necessary, at room temperature or at a temperature of 100 ° C. or lower to remove most or all of the organic solvent in the coating film by evaporation. This is achieved by pre-curing the coated surface by irradiating it with active energy rays and then heating to completely cure the coating.

The active energy rays include, for example, ultraviolet rays, laser rays, X rays, electron rays, ion beam rays and the like. Of these, ultraviolet rays are preferably used, and as a generator therefor, a mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, and a carbon arc lamp are used.
Metal, metal halide, gallium lamp, chemical lamp and the like.

It is possible to irradiate the coated surface with active energy rays before or after the composition is coated and the coated surface flows and becomes smooth or after sagging does not occur. preferable.

The irradiation with active energy rays is carried out to such an extent that the coating film of the present composition is pre-cured. Here, the pre-curing means that the coating film is cured to such an extent that the fluidity of the coating film stops and sagging does not occur in the vertical portion or the inclined portion during heating in the next step. The irradiation amount of the active energy ray for the pre-curing can be arbitrarily selected depending on the type of the active energy ray and the composition of the present composition.
000 mj / cm ² , 50 to 300 Kev for electron beam
It is preferable to irradiate up to 20 Mrad. These irradiation times are suitably from 1 second to 5 minutes.

In the method of the present invention, a coating film of the present composition is pre-cured by irradiation with active energy rays, and then the coating film is heated and completely cured. Here, “completely cured” refers to 80% by weight or more, particularly 90% by weight based on the above gel fraction.
It is preferable to perform the treatment so as to be in a range of not less than weight%.
Specifically, after the coating film of the present composition is pre-cured by irradiation with an active energy ray, it is cured at 60 to 200 ° C., particularly 120 ° C.
It can be completely cured by heating at １７０170 ° C. for 5 to 40 minutes. In this heating step, the coating surface does not flow even in the vertical portion, and a coating film having excellent smoothness can be formed. The gel fraction indicates the degree of crosslinking and curing of the coating film. The weight (W1) of the non-extracted coating film obtained by subjecting the heat-cured coating film to solvent extraction under acetone reflux for 6 hours is determined by the active energy ray. Value (weight%) divided by the weight (W2) of the coating film (the volatile component such as a solvent has been removed by heating at a temperature of 100 ° C. or less) before the irradiation.
It is.

[0048]

The present composition comprising a thermosetting resin composition and a resin composition curable by irradiation with active energy rays is used. The coating film is first pre-cured by irradiation with active energy rays. Thereafter, by heat curing, it was possible to improve the smoothness of the coated surface without deteriorating the chemical and physical performance of the coating film. In particular, the vertical portion and the inclined portion of the object to be coated are more likely to sag as the thickness of the applied liquid paint increases, but in the method of the present invention, the applied surface of the applied composition flows. Before sagging occurs at or after smoothing, the coated surface is pre-cured by irradiating the coated surface with active energy rays. It forms a coating film that has a firm feeling and a sense of depth and has excellent smoothness.

[0049]

EXAMPLES Examples and comparative examples of the present invention will be described below. Parts and percentages are based on weight, and the film thickness of the coating is for the cured coating.

1. Preparation of sample 1) Substrate: 0.8 m thick treated with zinc phosphate chemical conversion
m, a thermosetting epoxy resin-based cationic electrodeposition paint (“Elecron 9600” manufactured by Kansai Paint Co., Ltd., trade name) is applied to a thickness of 20 μm on a dull steel plate having a thickness of 20 μm.
Heat for 0 minutes to cure, then apply a polyester resin / melamine resin-based intermediate coating ("Lugabek KPX-6").
0 "(Kansai Paint Co., Ltd., trade name) was applied so as to have a film thickness of 35 μm, and was cured by heating at 140 ° C. for 30 minutes to obtain an object to be coated.

2) The present composition a): a polyester oligomer obtained by adding acrylic acid to a hydroxyl group-containing polyester resin (number average molecular weight 1500,
(It has two or more polymerizable unsaturated bonds per molecule.)
6 parts, pentaerythritol triacrylate 4 parts, 2
-Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone 1 (photopolymerization initiator) 1.8
Parts, t-butyl peroxy-2-ethylhexanoate (thermal polymerization initiator) 0.2 part, saturated polyester resin (hydroxyl value 100 mgKOH / g, acid value 5 mgKOH / g,
67 parts of number average molecular weight (about 6500), 23 parts of butylated melamine resin, and 60 parts of titanium white pigment are mixed with an equal weight mixed solvent of xylene and swazol 1500 (trade name, manufactured by Cosmo Oil, hydrocarbon solvent). This composition (a) was dispersed and adjusted to have a viscosity of 20 seconds / ford cup # 4/20 ° C. and a solid content of 60%.

B): 30 parts of a polyester oligomer obtained by adding acrylic acid to a hydroxyl group-containing polyester resin (number average molecular weight: 1500, having two or more polymerizable unsaturated bonds per molecule), pentaerythritol triacryle 20 parts, 2-benzyl-2-dimethylamino-1
8.8 parts of-(4-morpholinophenyl) -butanone 1 (photopolymerization initiator), 1 part of t-butylperoxy-2-ethylhexanoate (thermal polymerization initiator), saturated polyester resin (hydroxyl value) 100mgKOH / g, acid value 5mgK
OH / g, number average molecular weight of about 6500) 37 parts, butylated melamine resin 13 parts and titanium white pigment 60 parts were equi-weighted with xylene and swazol 1500 (trade name, manufactured by Cosmo Oil, hydrocarbon solvent). It was mixed and dispersed in a mixed solvent, and had a viscosity of 20 seconds / ford cup # 4/20 ° C. and a solid content of 6
This composition (b) adjusted to 5% was obtained.

C): 60 parts of a polyester oligomer obtained by adding acrylic acid to a hydroxyl group-containing polyester resin (number average molecular weight: 1500, having two or more polymerizable unsaturated bonds per molecule), pentaerythritol triacryle 40 parts, 2-benzyl-2-dimethylamino-1
17.6 parts of-(4-morpholinophenyl) -butanone 1 (photopolymerization initiator), 2 parts of t-butylperoxy-2-ethylhexanoate (thermal polymerization initiator), saturated polyester resin (hydroxyl value) 100 mg KOH / g, acid value 5 mg
15 parts of KOH / g, number average molecular weight of about 6500), 5 parts of butylated melamine resin, and 60 parts of titanium white pigment were equi-weighted with xylene and swazol 1500 (trade name, manufactured by Cosmo Oil, hydrocarbon solvent). It was mixed and dispersed in a mixed solvent, and had a viscosity of 20 seconds / ford cup # 4/20 ° C. and a solid content of 7
This composition (c) adjusted to 0% was obtained.

D): saturated polyester resin (having a hydroxyl value of 1)
75 parts of 00 mg KOH / g, acid value of 5 mg KOH / g, number average molecular weight of about 6500), 25 parts of butylated melamine resin and 60 parts of titanium white pigment were mixed with xylene and swazol 1
500 (Cosmo Oil, trade name, hydrocarbon-based solvent) mixed and dispersed in an equal weight mixed solvent and adjusted to a viscosity of 20 seconds / ford cup # 4/20 ° C. and a solid content of 55%. (D) was obtained.

2. EXAMPLES AND COMPARATIVE EXAMPLES With the substrates to be coated in a vertical position, the compositions a) to c) were applied by an air spray coating machine so that the film thickness became 40 μm. After confirming that the coated surface was smooth, the coated surface was pre-cured by irradiating the coating surface with ultraviolet rays of 2000 mj / cm ² using a metal halide lamp.
The irradiation time was about 2 seconds. Then, the pre-cured coating film was heated at 140 ° C. for 20 minutes to be completely cured.

In the comparative example, the present composition d) was applied to an object to be coated vertically so as to have a film thickness of 40 μm using an air spray coating machine, and was left standing at room temperature for 2 minutes while being kept vertical. The coating film was heated at 140 ° C. for 20 minutes to completely cure without UV irradiation.

Table 1 shows the performance test results of the obtained cured coating films.

[0058]

[Table 1]

The test method of the coating film in Table 1 is as follows.

Smoothness: The presence or absence of sagging on the coated surface was visually observed. ○ indicates that almost no dripping was observed, Δ indicates that dripping was slightly observed, and x indicates that dripping was frequently observed.

Coating appearance: The result of visual evaluation of the coated surface. O indicates almost no occurrence of wrinkles, dents, etc.
Δ indicates that wrinkles, dents and the like were slightly observed, and X indicates that wrinkles and dents were often observed.

Claims (2)

[Claims] 1. A liquid coating composition containing a thermosetting resin composition and an active energy ray-curable resin composition is applied to an object to be coated, and the coated surface is irradiated with active energy rays to pre-curing. And then heating to completely cure the coating film. 2. The coating film forming method according to claim 1, wherein the liquid coating composition is applied to an object to be coated, and after the coated surface flows and becomes smooth, it is pre-cured by irradiating with active energy rays. .