JP2002363480A - Photo-curing type primer composition and coating method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photo-curing type primer composition curing rapidly by irradiating light, having a good working property and excellent in adhesion to a base material and grinding property, and to provide a method for under- coating by using the same. SOLUTION: The photo-curing type primer composition contains (A) an acrylic resin containing a polymerizable unsaturated group at its side chain via a urethane bond, and also containing 0.2-2.0 mol/kg polymerizable unsaturated group in the solid portion of the resin (A), (B) a urethane (meth) acrylate oligomer containing >=1 polymerizable unsaturated groups in one molecule, (C) a polymerizable unsaturated compound, (D) an extender and (E) a photo-polymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable primer composition which cures quickly by light irradiation, has good workability, and is excellent in adhesion to materials and polishing properties, and an undercoating method using the same. About.

[0002]

2. Description of the Related Art Conventionally, for repair coating of an automobile outer panel, a sheet metal putty is mainly applied to a damaged portion with a spatula or the like, and the putty surface is polished after drying, and then a finish coat is applied thereon. In order to ensure the properties, a primer surfacer is applied, and after drying, the coated surface is polished smoothly, and then a top coat is applied. Time is spent. Therefore, in order to reduce the time required for the entire repair coating, repair coating using a photocurable putty composition has been studied in recent years.
Such a photocurable putty composition is disclosed in, for example,
JP-A-4-117588, JP-A-9-137089, JP-A-9-100306 and the like have proposed a photocurable coating composition containing a polymerizable unsaturated group-containing resin and a photopolymerization initiator. However, when this composition is used as a repair primer surfacer, there is a problem that the coating properties such as abrasiveness, hardness, adhesion, and water resistance are insufficient.

[0003]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, as a primer surfacer, a specific acrylic resin having a polymerizable unsaturated group via a urethane bond and a urethane (meth) ) It was found that the use of a paint having a specific composition containing an acrylate oligomer greatly improved the working efficiency without affecting the performance of the coating film, and completed the present invention.

That is, the present invention provides: (A) an acrylic resin containing a polymerizable unsaturated group in a side chain via a urethane bond and containing a polymerizable unsaturated group in the solid content of the resin (A) in an amount of 0.2 to 2.0 mol / kg;
(B) a urethane (meth) acrylate oligomer containing one or more polymerizable unsaturated groups in one molecule, (C) other polymerizable unsaturated compounds, (D) extender pigment, and (E)
1. A photocurable primer composition comprising a photopolymerization initiator, 2. The photocuring according to claim 1, wherein the acrylic resin (A) is obtained by reacting a hydroxyl group-containing acrylic resin (a) with a compound (b) having an isocyanate group and a polymerizable unsaturated group in one molecule. 2. a mold primer composition; 2. The photocurable composition according to claim 1, wherein the acrylic resin (A) is obtained by reacting an isocyanate group-containing acrylic resin (c) with a compound (d) having a hydroxyl group and a polymerizable unsaturated group in one molecule. 3. a mold primer composition; Urethane (meth) acrylate oligomer (B)
Are obtained by reacting a compound (e) containing two or more isocyanate groups in one molecule with a hydroxyl group-containing polymerizable unsaturated monomer (f) and a monohydric alcohol (g). 4. The photocurable primer composition according to item 1, The proportions of the components (A), (B) and (C) are such that the component (A) is 5 to 90% by weight, the component (B) is 5 to 90% by weight, ) Component is 5-6
5. The photocurable primer composition according to any one of items 1 to 4, which is 0% by weight; 6. The photocurable primer composition according to item 1, wherein resin particles are used in combination with the extender pigment (D). 7. The photocurable primer composition according to any one of items 1 to 6, wherein the Ti value is 5 or more; 8. A coating method, comprising applying a photocurable putty composition to a substrate surface, and then applying the photocurable primer composition according to any one of 1 to 7 above, A coating layer of a photocurable putty composition and a coating layer of a photocurable primer composition formed on the coating surface,
Item 9. The coating method according to Item 8, wherein both coating surfaces are cured simultaneously by irradiating a light beam.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the acrylic resin (A) contains a polymerizable unsaturated group in a side chain via a urethane bond, and the polymerizable unsaturated group is contained in a solid content of the resin (A). It contains 0.2 to 2.0 mol / kg.

The polymerizable unsaturated group is not particularly limited as long as it causes a radical polymerization reaction by light such as visible light, near infrared light and ultraviolet light.
Examples include an acryloyl group, a vinyl group, a vinyl ether group, and an allyl group. Particularly, a (meth) acryloyl group is preferable.

[0007] In the present specification, "(meth) acryloyl group" means "acryloyl group or methacryloyl group".
Represents

[0008] The amount of the polymerizable unsaturated group depends on the resin (A)
0.2 to 2.0 mol / kg in solid content, preferably 0.1 to 2.0 mol / kg.
3 to 1.5 mol / kg is preferred. When the amount of the polymerizable unsaturated group is less than 0.2 mol / kg, the crosslinking is insufficient and the physical properties of the film are deteriorated.
If it exceeds g, the curing shrinkage becomes too large, and the adhesion is undesirably reduced.

The acrylic resin (A) has good adhesion of the resulting coating film, and it is preferable to introduce a polymerizable unsaturated group via a urethane bond by utilizing the reaction of isocyanate / hydroxyl group. It is.

As a method for producing the acrylic resin (A), there is firstly a method of reacting a hydroxyl group-containing acrylic resin (a) with a compound (b) having an isocyanate group and a polymerizable unsaturated group in one molecule. . In this case, it is preferable that the conditions are such that the hydroxyl groups are excessive and unreacted isocyanate does not remain.

The above-mentioned hydroxyl-containing acrylic resin (a) is a copolymer obtained by copolymerizing a polymerizable unsaturated monomer mixture containing a hydroxyl-containing polymerizable unsaturated monomer in the presence of a polymerization initiator. Can be preferably used. Examples of the hydroxyl group-containing polymerizable unsaturated monomer include hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, and a product adduct of hydroxyethyl (meth) acrylate and lactone; "," Placcel FM3 "(manufactured by Daicel Chemical Industries, Ltd.), polyethylene glycol mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and the like, alone or Two or more types can be appropriately selected and used.

The above-mentioned hydroxyl group-containing acrylic resin (a) includes, in addition to the hydroxyl group-containing polymerizable unsaturated monomer as an essential component, other polymerizable unsaturated monomers copolymerizable with the monomer as required. May be used as a copolymer component.

The other polymerizable unsaturated monomer can be used without any particular limitation as long as it is copolymerizable with the above-mentioned hydroxyl group-containing polymerizable unsaturated monomer. Specifically, methyl (meth) acrylate , Ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) A) acrylates, lauryl (meth) acrylates, monoesters of acrylic acid or methacrylic acid with monoalcohols having 1 to 24 carbon atoms such as isobornyl (meth) acrylate, styrene, α-methylstyrene, acrylic acid, methacrylic acid, Crotonic acid, itaconic acid, maleic acid Fumaric acid, 2-carboxyethyl (meth) acrylate, 2-carboxypropyl (meth) acrylate, 5-carboxypentyl (meth) acrylate, glycidyl (meth) acrylate, .gamma.
(Meth) acryloyloxypropyltrimethoxysilane and the like. These may be used alone,
Two or more types can be appropriately selected and used.

In the present invention, the hydroxyl group contained in the hydroxyl group-containing acrylic resin (a) obtained as described above and the compound (b) having an isocyanate group and a polymerizable unsaturated group in one molecule are contained. By reacting with an isocyanate group, a polymerizable unsaturated group can be introduced into a side chain of the acrylic resin (A) via a urethane bond.

Examples of the compound (b) having an isocyanate group and a polymerizable unsaturated group in one molecule include an isocyanate group containing an isocyanate group such as isocyanate ethyl (meth) acrylate and m-isopropenyl-α, α-dimethylbenzyl isocyanate. A polymerizable unsaturated monomer or a product obtained by an addition reaction of a compound having two isocyanate groups with a hydroxyl group-containing polymerizable unsaturated monomer in equimolar amounts can be used.

Examples of the compound having two isocyanate groups include hexamethylene diisocyanate, trimethylene diisocyanate, 1,4-tetramethylene diisocyanate, pentamethylene diisocyanate,
Aliphatic diisocyanate compounds such as 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4- (or- 2,6-) diisocyanate,
Alicyclic diisocyanate compounds such as 1,3-cyclopentane diisocyanate and 1,2-cyclohexane diisocyanate, xylylene diisocyanate, meta-xylylene diisocyanate, tetramethyl xylylene diisocyanate, tolylene diisocyanate, 4,4'-
And aromatic diisocyanate compounds such as diphenylmethane diisocyanate.

The hydroxyl group-containing polymerizable unsaturated monomer can be appropriately selected from those described in the section of the hydroxyl group-containing acrylic resin (a).

Next, as a method for producing an acrylic resin (A) containing a polymerizable unsaturated group in a side chain via a urethane bond, an isocyanate group-containing acrylic resin (c) and a hydroxyl group in one molecule and a polymerizable unsaturated A method of reacting the compound (d) having a group is also included.

The isocyanate group-containing acrylic resin (c) is obtained by copolymerizing a polymerizable unsaturated monomer mixture containing an isocyanate group-containing polymerizable unsaturated monomer in the presence of a polymerization initiator. Coalescing can be suitably used.
As the isocyanate group-containing polymerizable unsaturated monomer,
For example, isocyanatoethyl acrylate, m-isopropenyl-α, α-dimethylbenzyl isocyanate and the like can be mentioned. Further, the compound (b) having an isocyanate group and a polymerizable unsaturated group in one molecule may be used. These can be used alone or by appropriately selecting two or more kinds.

The other polymerizable unsaturated monomer other than the isocyanate group-containing polymerizable unsaturated monomer can be copolymerized with the above-mentioned isocyanate group-containing polymerizable unsaturated monomer, and can quickly react with the isocyanate group. A monomer having no reactive functional group is preferable, and specifically, methyl (meth)
Acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2
Monoesters of acrylic acid or methacrylic acid such as ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl (meth) acrylate and isobornyl (meth) acrylate with monoalcohols having 1 to 24 carbon atoms, styrene, α -Methylstyrene and the like. These may be used alone,
Two or more types can be appropriately selected and used.

Examples of the compound (d) having a hydroxyl group and a polymerizable unsaturated group in one molecule include hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate,
Product adduct of hydroxyethyl (meth) acrylate and lactone; "Placcel FA2", "Placcel FM"
3 "(manufactured by Daicel Chemical Industries, Ltd.), polyethylene glycol mono (meth) acrylate, 2-hydroxy-3-
Obtained by adding an equimolar addition reaction of a hydroxyl group-containing polymerizable unsaturated monomer such as phenoxypropyl (meth) acrylate or a compound having two hydroxyl groups with an isocyanate group-containing polymerizable unsaturated monomer as described above. And these can be used alone or by appropriately selecting two or more kinds.

In the reaction of the component (a) / component (b) and the reaction of the isocyanate group and the hydroxyl group in the reaction of the component (c) / component (d), the urethane-forming reaction is promoted to promote the polymerization. It is preferable to carry out the reaction at a reaction temperature of 20 to 80 ° C. using a solvent, a urethanization catalyst, a polymerization inhibitor and the like, if necessary, so that the unsaturated group does not disappear.

The acrylic resin (A) may contain not only a polymerizable unsaturated group but also a reactive functional group. In this case, a compound containing a reactive functional group capable of reacting with the reactive functional group in the resin (A) may be further added. As the combination of the reactive functional groups, a conventionally known combination can be selected without any particular limitation. For example, a combination of a hydroxyl group and an isocyanate
And a combination of an epoxy group and an amino group, an epoxy group and a carboxyl group, a hydroxyl group and an alkoxysilyl group. Specifically, for example, when the resin (A) has a hydroxyl group, a polyisocyanate compound or the like may be used in combination. When such a compound is used, it is suitably used in an amount of 30% by weight or less based on the whole resin solids.

The acrylic resin (A) has a weight average molecular weight before introduction of a polymerizable unsaturated group of 5,000 to 5,000.
50,000 and a glass transition temperature in the range of -50 to 100C, preferably -50 to 70C. If the weight-average molecular weight is less than 5,000, the physical properties of the film will be reduced, while if it exceeds 50,000, the viscosity will be high and handling will be difficult, which is not preferable. If the glass transition temperature is lower than −50 ° C., tack tends to remain after curing, and the polishing property is reduced.

The glass transition temperature mentioned here is measured as follows. A resin solution equivalent to 10 mg of solid content is placed in a dedicated aluminum pan having a diameter of 4.5 mm and a depth of 2 mm, and dried under reduced pressure at 50 ° C. for 3 hours to completely remove the solvent to obtain only the resin solid content, which is used as a sample for measurement. . The measurement was performed using SSC-5300.
The temperature is increased at a rate of 20 ° C./min by using a mold type thermal analyzer (manufactured by Seiko Denshi Kogyo Co., Ltd.), and the temperature is increased from about 50 ° C. below the expected glass transition temperature.

In the present invention, the urethane (meth) acrylate oligomer (B) is blended for improving the adhesion and water resistance, and has a weight average molecular weight of 400 to 400.
3,000, preferably 400 to 2,000 can be suitably used. If it is less than 400, the curing shrinkage becomes large because the amount of the unsaturated group becomes large, and the adhesion is reduced.
If it exceeds 3,000, it is not preferable because it is not so effective in improving the adhesion.

The amount of the polymerizable unsaturated group of the urethane (meth) acrylate oligomer (B) is preferably contained in the solid content of the component (B) in the range of 1.0 to 2.5 mol / kg. If it is less than 1.0 mol / kg, the crosslinking is insufficient and the physical properties of the film are reduced, and the adhesion and water resistance are reduced.
If it exceeds 5 mol / kg, the curing shrinkage becomes too large and the adhesiveness is undesirably reduced.

The urethane (meth) acrylate oligomer (B) is preferably a compound (e) containing two or more isocyanate groups in one molecule, a hydroxyl-containing polymerizable unsaturated monomer (f), Those obtained by reaction with a hydric alcohol (g) are preferred.

Compound (e) containing two or more isocyanate groups in one molecule includes hexamethylene diisocyanate, trimethylene diisocyanate, 1,4-tetramethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, , 2
Aliphatic diisocyanate compounds such as butylene diisocyanate and trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4- (or -2,6-) diisocyanate, 1,3 -Cyclopentane diisocyanate, 1,
Alicyclic diisocyanate compounds such as 2-cyclohexane diisocyanate, xylylene diisocyanate, meta-xylylene diisocyanate, tetramethyl xylylene diisocyanate, tolylene diisocyanate, 4,
A diisocyanate compound itself such as an aromatic diisocyanate compound such as 4'-diphenylmethane diisocyanate, or an adduct of each of these diisocyanate compounds with a polyhydric alcohol, a low molecular weight polyester resin or water, or cyclization of the above-described diisocyanate compounds Examples of the polymer include an isocyanate biuret compound. Among them, a cyclic trimer of hexamethylene diisocyanate is particularly preferable.

The hydroxyl group-containing polymerizable unsaturated monomer (f) is
It is used to introduce a polymerizable unsaturated group into the urethane (meth) acrylate oligomer (D). Examples thereof include hydroxyethyl (meth) acrylate, hydroxybutyl (meth) acrylate, and hydroxyethyl ( Product adduct of (meth) acrylate and lactone; "Placcel FA2", "Placcel FM3" (all manufactured by Daicel Chemical Industries, Ltd.), polyethylene glycol mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (Meth) acrylate and the like can be used.

The monohydric alcohol (g) is used in the synthesis of the urethane (meth) acrylate oligomer (D) for the purpose of blocking excess isocyanate groups and for adjusting the concentration of unsaturated groups. As the monohydric alcohol (g), conventionally known ones can be used without limitation, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, i-butyl alcohol, 2- Ethyl butanol, 2-ethylhexanol,
Examples include benzyl alcohol, lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether.

At the time of the reaction of component (e) / component (f) / component (g), a solvent, if necessary, may be added so as to accelerate the urethanization reaction so that the polymerizable unsaturated group does not disappear. Using a urethanization catalyst, polymerization inhibitor, etc., the reaction temperature is 20 to
It is preferred to carry out at 80 ° C. When the monohydric alcohol (g) is not used, it is preferable to use an equivalent amount of an isocyanate group and a hydroxyl group, or to carry out the reaction until the isocyanate group disappears.

In the present invention, the other polymerizable unsaturated compound (C) is compounded as a reactive diluent and for adjusting the unsaturated group concentration in the coating composition. Monomers having these or oligomers other than the above (B) can be suitably used. Specifically, ethyl (meth) acrylate, butyl (meth) acrylate,
2-ethylhexyl (meth) acrylate, isobornyl (meth) acrylate, norbornyl (meth) acrylate, adamantyl (meth) acrylate, neopentyl glycol di (meth) acrylate, hydroxyethyl (meth) acrylate Trimethylolpropane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, dipentaerythritol (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, 2 , 2-Bis (4- (3-methacryloxy-2-hydroxypropoxy) -phenyl)
Mono- or polyvalent alcohol (meth) acrylates such as propane, di (methacryloxyethyl) trimethylhexamethylene diurethane, and 2,2-bis (4-methacryloxypolyethoxyphenyl) propane; (Meth) acryloyloxymethoxycarbonylphthalic acid,
4- (meth) acryloyloxyethoxycarbonylphthalic acid and other 4- (meth) acryloyloxyl group-containing aromatic polycarboxylic acids and anhydrides thereof; styrene, α
-Methylstyrene, chlorostyrene, vinyltoluene,
aromatic vinyl compounds such as t-butylstyrene and divinylbenzene; diallyl phthalate, diallyl isophthalate, triallyl phthalate; epoxy acrylate;
Ethylene oxide modified epoxy acrylate, polyester acrylate, polydimethyl silicon di (meth)
Acrylate and the like can be mentioned, and these can be used alone or in combination of two or more.

When the components (A), (B) and (C) are used in combination, the proportions used are (A)
With respect to the total solid content of the component (B) and the component (C),
It is preferable that the component (A) is 5 to 90% by weight, the component (B) is 5 to 90% by weight, and the component (C) is 5 to 60% by weight. If the content of the acrylic resin (A) is less than 5% by weight, tackiness remains and the polishing property is reduced. On the other hand, if it exceeds 90% by weight, the adhesion and the water resistance are undesirably reduced. If the amount of the urethane (meth) acrylate oligomer (B) is less than 5% by weight, the adhesion and the water resistance are reduced.
When the amount of the polymerizable unsaturated compound (C) is less than 5% by weight, the solid content at the time of coating decreases, and the property of the coating film decreases due to the decrease in the unsaturated group concentration in the coating. However, it is not preferable because the polishing ability is reduced.

The extender pigment (D) used in the photocurable primer composition of the present invention is blended for the purpose of, for example, relieving the stress of the coating film and securing the adhesion, and those having a high light transmittance. desired.

Examples of the extender include talc, mica, barium sulfate, kaolin, calcium carbonate, clay, silica, quartz, glass and the like.
It can be used in combination of two or more species.

The extender pigment (D) is the total resin solid content in the composition (total amount of the components (A), (B) and (C)).
1 to 300 parts by weight, preferably 5 to 100 parts by weight
２００200 parts by weight. If the amount is less than 1 part by weight, the polishing property is reduced, and the internal stress is generated, so that the adhesion and the water resistance are reduced. If the amount exceeds 300 parts by weight, the viscosity of the paint is increased and the workability is reduced. It is not preferable.

Further, other fillers can be used in combination with the extender (D) as required. As the filler, for example, titanium white, red iron, carbon black,
Color pigments such as iron black, aluminum hydroxide, magnesium hydroxide, and the like can be included.

In addition, resin particles may be used in combination with the extender pigment (D), if necessary, from the viewpoint of controlling the viscous behavior. As the resin particles, conventionally known resin particles such as polymer beads, finely crushed polymers of the above-mentioned monomers, and gelled polymer fine particles (for example, JP-A-51-126287). JP-A-53-133233
JP, JP-A-53-133236, JP-A-Showa 56
Gelled polymer particles obtained by emulsion polymerization of a monomer mixture containing divinyl monomers in the presence of an allyl group-containing reactive emulsifier. (See, for example, JP-A-3-66770), the resin (A),
Since it has excellent dispersibility in the components (B) and (C), it can be suitably used.

The photopolymerization initiator (E) used in the photocurable primer composition of the present invention generates radicals when excited by light energy of light irradiation such as ultraviolet light, visible light, and near infrared light. , As long as it initiates radical polymerization, for example, 4-phenoxydichloroacetophenone,
4-t-butyl-dichloroacetophenone, 4-t-butyl-trichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl)
-2-hydroxy-2-methylpropan-1-one, 1
-(4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 4- (2-hydroxyphenoxy) -phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenylketone,
2-methyl-1- [4- (methylthio) phenyl] -2-
Acetophenone compounds such as morpholinopropanone-1; thioxanthone, 2-chlorothioxanthone,
Thioxanthone compounds such as methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, and 2,4-dichlorothioxanthone; benzyl,
Benzyl compounds such as benzyl dimethyl ketal, benzyl-β-methoxyethyl acetal, 1-hydroxycyclohexyl phenyl ketone; benzophenone, o-
Methyl benzoyl benzoate, Michler's ketone, 4,
4'-bisdiethylaminobenzophenone, 4,4'-
Benzophenone compounds such as dichlorobenzophenone;
Benzoin ether compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isobutyl ether; camphor-quinone, anthraquinone, 3-ketocoumarin, α-naphthyl, 2,4,6
-Trimethylbenzoyl, diphenylphosphine oxide, acylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 10-butyl-2-chloroacridone, Fluorenone and the like. In addition to these, known initiator systems include ionic dye-counter ion compounds such as cationic dye-borate anion compounds (for example, JP-A-1-60606 and JP-A-2-11607), and metal arrays. Compounds and organic dyes (for example,
JP-A-4-363308 and JP-A-5-17525). Also, cyanine dyes, phthalocyanine dyes, pyrylium dyes, thiopyrylium dyes, azurenium dyes, squarylium dyes, N
i, Cr and other metal complex dyes, naphthoquinone / anthraquinone dyes, indophenol dyes, indoaniline dyes, triphenylmethane dyes, triallylmethane dyes, aminium / diimmonium dyes, nitroso compounds And complexes of cationic dyes such as those described in JP-A-62-143044 and JP-A-2-11-11.
607, JP-A-3-111402, JP-A-5-19
No. 4619, JP-A-4-77503, etc., and a near-infrared light-absorbing cationic dye-borate anion complex, and a cyanine dye disclosed in JP-A-2-189548 and halogenation. A triazine compound or a cyanine compound having a methyl group and a metal arene compound; a metal arene compound and a squarylium dye disclosed in JP-A-5-17525;
And the like.

The amount of the photopolymerization initiator (E) is 0.01 to 20 parts by weight based on 100 parts by weight of the total resin solids (resins (A), (B) and (C)) in the composition. It is about parts by weight.

The photopolymerization initiator (E) is preferably used in combination with an oxygen removing agent capable of absorbing oxygen in a free radical chain process or an active hydrogen donor chain transfer agent. Examples of the oxygen removing agent include phosphine, phosphite, phosphonate, stannous salt, and other compounds that are easily oxidized by oxygen. Examples of the chain transfer agent include triethylamine, N-methyldiphenylamine, Tertiary amines such as isoamyl 4-dimethylaminobenzoate, triethanolamine and dimethylethanolamine, dimethylaminoethyl methacrylate; N-phenylglycine, 2-mercaptobenzoxazole, 2-
Mercaptobenzothiazole; 2,6-diisopropyl-N, N-dialkylaniline, N, N, 2,4,6-
N, N-dialkylaniline such as pentamethylaniline and the like can be mentioned.

The photopolymerization initiator (E) may be used in combination with a boron sensitizer. Examples of the boron sensitizer include tetra-n-butylammonium, n-butyltriphenylboron, tetramethylammonium n-butyltriphenylboron, tetra-n-butylphosphonium n
-Butyltriphenylboron and the like.

The photopolymerization initiator (E) may be used in combination with an organic peroxide. Examples of the organic peroxide include benzoyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide and the like.

The primer composition of the present invention preferably contains a phosphate group-containing compound from the viewpoint of improving the adhesion to the substrate. Examples of the phosphoric acid group-containing compound include acidic phosphoric acid esters such as dibutyl phosphate and 2-ethylhexyl phosphate, acidic phosphites, polyphosphoric acid compounds thereof, and phosphoric acid copolymer resins.
Further, a phosphoric acid copolymer resin may be used as the resin (A), and a phosphate group-containing monomer may be used as the polymerizable unsaturated compound (C).

The amount of the phosphoric acid group-containing compound is defined as a phosphoric acid group based on the total amount of all resin solids (the total amount of the pre-resins (A), (B) and (C)) in the composition. 0.01 ~
It is desirably determined to be 1.0 mmol / g, preferably 0.05 to 0.5 mmol / g.

Further, the primer composition of the present invention is preferably used in order to improve the adhesion to the substrate and the overcoat layer and to improve the workability.
Further, if necessary, a cellulose derivative, a non-reactive diluent, a thermoplastic resin and the like can be blended. Cellulose acetate butyrate (CAB) as a fibrin derivative,
Nitrocellulose and the like, and further using a graft copolymer of a cellulose derivative such as the CAB with a monomer mixture such as a hydroxyl-containing unsaturated monomer or another ethylenically unsaturated monomer. Is also good. Examples of the non-reactive diluent include an organic solvent, and examples of the thermoplastic resin include polyethylene, polystyrene, polymethyl methacrylate, polyvinyl acetate, polyvinyl chloride, and polycaprolactone. Of these, the use of a fibrous derivative such as a CAB graft copolymer is particularly preferable because the hydroxyl groups are oriented on the surface of the coating film and the adhesion is improved when the overcoat is a urethane curing system.

These are within a range having good compatibility with the above-mentioned resins (A), (B) and (C), and are 40% by weight or less, preferably 1 to 20% by weight, based on the total solid content thereof.
It is desirable to be added in an amount of about% by weight.

The primer composition of the present invention containing the above components preferably has a Ti value of 5 or more, preferably 5 to 8 from the viewpoint of storage stability. In the present specification, the Ti value is defined as a TI (Thixotropy index: rotation number 6) indicated in the evaluation of non-Newtonian properties of a coating composition by a rotational viscometer.
(the ratio of viscosity at 60 rpm to 60 rpm) (JI
SK 5400 4.5.3 (1990)), and a larger Ti value indicates a thixotropic fluid. If the Ti value is less than 5, the storage stability may be poor, which is not preferable.

The primer composition of the present invention can be stored by filling the above-mentioned paint components in a usual round can or the like.
To prevent light from entering the can when opening and closing the lid,
It is preferable to fill a small-mouthed container as shown in FIG. In addition, if the filling can has such a shape, depending on the pigment concentration, if the paint is settled in the form of a soft cake on the bottom of the can, shake the can with the lid closed before use to stir. Thus, the paint can be returned to a uniform state.

The primer composition of the present invention can also be obtained as an aerosol paint by adding a propellant to the above paint component and filling the paint component together with the propellant in an aerosol container. As the propellant, known dimethyl ether, L
P gas or the like can be used alone or in combination.

The photocurable primer composition of the present invention obtained as described above can be directly applied to a substrate surface or a putty painted surface, and the substrate surface may be made of iron, zinc, aluminum or the like. Examples of the surface include a metal surface, a chemically treated surface thereof, plastic, wood, and the like, and an old coating film surface coated thereon. In the repair coating, if the base material surface is a damaged portion, it is appropriate to sand the damaged portion as necessary and around the damaged portion as necessary. Examples of the putty-coated surface include a surface polished after applying and drying a conventionally known lacquer-based, polyester-based, or epoxy-based putty on such a repaired surface.

In the present invention, a coating method comprising coating a photocurable putty composition on the above-mentioned substrate surface and then coating the photocurable primer composition of the present invention obtained as described above on the photocurable putty composition is used. Is also provided.

As the photocurable putty composition, one molecule of a polymerizable unsaturated group which causes a radical polymerization reaction by light such as visible light, near-infrared light and ultraviolet light as exemplified by the above-mentioned photocurable primer composition. Any known resin containing at least one polymerizable unsaturated group-containing resin, a polymerizable unsaturated compound, a photopolymerization initiator, and a filler such as a pigment can be used without particular limitation. Kaihei 9-1
No. 76517 and JP-A-9-302262.

The application of the photocurable putty composition can be appropriately selected according to the state of the damaged portion which is the substrate surface, and the photocurable putty composition is appropriately applied with the polymerizable unsaturated compound as described above. The method is performed by adjusting the viscosity and spraying the damaged portion, or filling the damaged portion with a spatula or the like.

The obtained putty-coated surface may be cured by light irradiation, or a photocurable primer composition may be applied in an uncured state, and both layers may be cured simultaneously by light irradiation. In particular, from the viewpoint of reducing the number of steps, it is preferable to apply both compositions over and over on a wet-on-wet basis, and to irradiate light to cure both coating surfaces simultaneously.

When the wet-on-wet coating process is employed as described above, the coating layer formed of the photo-curable putty composition and the photo-curable primer composition may both easily transmit light. Desirable, especially PVC
(Pigment volume concentration) is 10-30 for the photocurable putty composition.
%, The content of the photocurable primer composition is preferably in the range of 10 to 40%. Further, both compositions preferably contain an extender pigment having a high light transmittance as a pigment to be used, and a photopolymerization initiator used in both compositions includes visible light or near light for curing to the inside of a coating film. Compounds that excite at long wavelengths such as infrared light are preferred.

The coating of the photocurable primer composition can be performed by a conventionally known method such as spraying, roll coating, gravure coating, and screen, and the coating viscosity is appropriately adjusted. It may be spray-painted. The primer coating has a dry film thickness of 30 to 500 μm, preferably 50 to 500 μm.
It is within the range of 300 μm. Primer coating cured by light irradiation, without polishing, or by polishing,
Used for top coat.

The light source used for light irradiation can be used without any particular limitation, and examples thereof include a halogen lamp, a xenon lamp, a krypton lamp, a metal halide lamp, a fluorescent lamp, sunlight, a semiconductor laser, and a light emitting diode. No. Irradiation conditions can be appropriately selected depending on the thickness and composition of the putty layer and the primer layer.

As the top coat, there can be used any organic solvent-based or water-based top coat such as acrylic lacquer, urethane-curable paint, fluororesin-based paint and the like, which can be used without particular limitation. System paints are preferred.

[0061]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. “Parts” and “%” are “parts by weight” respectively.
And "% by weight".

Production Example 1 of Acrylic Resin A reactor was equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, a dropping pump, a dry air blowing pipe, 50 parts of xylene was charged, and the temperature was raised to 115 ° C. while stirring. After that, a mixture of the monomer and the polymerization initiator shown in Table 1 below was dropped at a constant rate over 3 hours using a dropping pump while maintaining the mixture at 115 ° C. 1.5 hours after completion of dropping 110
Then, a solution prepared by dissolving 0.5 part of an additional polymerization initiator in 10 parts of xylene was added dropwise at a constant rate over 1.5 hours, and the mixture was further kept at 110 ° C. for 3 hours and stirring was continued. Then, add 25 parts of xylene and dilute with 80
Cooled to ° C. Subsequently, while supplying dry air to the liquid phase, 0.06 parts of hydroquinone monomethyl ether as a polymerization inhibitor, 0.06 parts of dibutyltin dilaurate as a urethanization catalyst, and equimolar adducts of isophorone diisocyanate and hydroxyethyl acrylate18. Two copies,
14 parts of xylene was added and the temperature was kept at 80 ° C. for 7 hours to complete the addition reaction, thereby obtaining an acrylic resin solution (A1). The resin solution (A1) has a nonvolatile content of 55% and a Gardner viscosity of Z6.
Was a homogeneous and clear solution. The resin had a weight average molecular weight before introduction of a polymerizable unsaturated group of 17,000 and a glass transition temperature of 60 ° C.

Production Examples 2 to 6 The same procedures as in Production Example 1 were carried out except that the composition was as shown in Table 1, and the acrylic resin solutions (A2) to (A2)
6) was obtained. The properties of the obtained resin solution are also shown in Table 1.

Production Example 7 A glycidyl group-containing acrylic resin was synthesized in the same manner as in Production Example 1, except that the monomers and the polymerization initiator were mixed as shown in Table 1. Subsequently, while maintaining the system at 110 ° C., while supplying dry air to the liquid phase, as a polymerization inhibitor,
0.06 parts of hydroquinone monomethyl ether, 1.0 part of tetrabutylammonium bromide as an esterification catalyst, 4.6 parts of acrylic acid, and 14 parts of xylene were added, and the mixture was maintained at 110 ° C. for 7 hours to complete the addition reaction. Thus, an acrylic resin solution (A7) having a radically polymerizable unsaturated group in a side chain without via a urethane bond was obtained. Table 1 also shows the property values of the obtained resin solution.

[0065]

[Table 1]

Production Example 8 Production of Urethane Acrylate Oligomer A reactor was equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, a dropping pump, and a blowing pipe for dry air.
"N-3300" (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.)
Solid content 100%, cyclic trimer of hexamethylene diisocyanate, NCO content 21.5%) 583.5 parts, xylene 26 parts, hydroquinone monomethyl ether 0.47 part as a polymerization inhibitor, dibutyltin dilaurate as a urethanization catalyst 0.47 parts were charged, and the mixture was stirred while supplying dry air to the liquid phase, and heated to 80 ° C. continue,
A mixture of 288.3 parts of hydroxybutyl acrylate and 66.7 parts of n-butanol was dropped at a constant rate over 3 hours using a dropping pump while maintaining the temperature at 80 ° C., and the addition reaction was maintained at 80 ° C. for 5 hours. The mixture was completed and cooled while diluting with 216 parts of isopropanol to obtain a urethane (meth) acrylate oligomer solution (B1).
The obtained oligomer solution (B1) was a uniform and transparent solution having a nonvolatile content of 80% and a Gardner viscosity W. The unsaturated group concentration is 2.12 mol / kg, and the weight average molecular weight is 940
Met.

Preparation Examples 9 and 10 The same procedure as in Preparation Example 8 was repeated except that the isocyanate compound, the hydroxyl group-containing polymerizable unsaturated monomer and the monohydric alcohol were mixed as shown in Table 2, and the respective oligomer solutions were prepared. (B2) and (B3) were obtained. Table 2 also shows the property values of the obtained oligomer solution.

[0068]

[Table 2]

Preparation of Primer Composition Example 1 In a container, 90.9 parts of an acrylic resin solution (A1), 50 parts of a urethane acrylate oligomer solution (B1), 10 parts of isobornyl acrylate, and “Microace L-1” ( Note 1) 50 parts, “Varita” (Note 2) 150 parts, and 50 parts of xylene were blended, mixed and stirred, and charged with glass beads having a diameter of 1.5 mm, and dispersed in a batch sand for 20 minutes. Thereto, 4 parts of “Kayamer PM1” (Note 3) and 4 parts of a photopolymerization initiator “Irgacure 819” (Note 4) were added and stirred to obtain a primer composition (P1). The Ti value of the primer composition (P1) was 5.5.

(Note 1): “Micro Ace L-1”: Talc, manufactured by Nippon Talc (Note 2): “Varita”: Sedimentable barium sulfate 100, manufactured by Sakai Chemical Industry Co., Ltd. (Note 3): “Kayamar PM” -21 ": Unsaturated group-containing phosphate monomer manufactured by Nippon Kayaku Co., Ltd. (Note 4):" Irgacure 819 ": Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide manufactured by Ciba Specialty Chemicals. .

(Note 5): Fine resin particles G: In a 1-liter flask equipped with a stirrer, a thermometer, a cooling tube and a heating mantle, 3547.5 parts of deionized water and "Latemul S-12" were added.
0A "(manufactured by Kao Corporation, sulfosuccinic acid-based allyl group-containing anionic reactive emulsifier, 50% aqueous solution), and the mixture was heated to 90 ° C with stirring. Next, "VA
20% of an aqueous solution obtained by dissolving 12.5 parts of "-086" (Wako Pure Chemical Industries, Ltd., water-soluble azoamide polymerization initiator) in 500 parts of deionized water was added. After 15 minutes, 300 parts of styrene,
400 parts of methyl methacrylate, n-butyl acrylate
Then, 5% of a monomer mixture consisting of 200 parts of 1,6-hexanediol diacrylate and 100 parts of 1,6-hexanediol diacrylate was added and stirred for 30 minutes. Thereafter, the dropping of the remaining monomer mixture and the aqueous solution of the polymerization initiator is further started. The dropping of the monomer mixture is performed in 3 hours, and the dropping of the aqueous solution of the polymerization initiator is performed over 3.5 hours. did. After the dropping of the aqueous polymerization initiator solution, the temperature was further maintained at 90 ° C. for 30 minutes, cooled to room temperature, taken out using a filter cloth, and an aqueous dispersion of an aqueous gelled fine particle polymer having a solid content of 20% was obtained. Its particle size was 72 nm. This was dried on a stainless steel pad to obtain resin fine particles G.

Examples 2 to 11 and Comparative Examples 1 to 5 The same procedures as in Example 1 were carried out except that the components shown in Table 3 were used, and the respective primer compositions (P
2) to (P16) were obtained. In Comparative Example 5, a composition excluding the pigment was prepared.

The Ti value of each of the primer compositions obtained above was measured, and further stored in the container shown in FIG.
The state of the coating liquid after storage at 0 ° C. for 3 months was evaluated. ○ indicates no abnormality at all, △ indicates slight increase in viscosity but no sedimentation or aggregation of the pigment, and X indicates that the pigment sedimented and aggregated to form a hard cake.

[0074]

[Table 3]

Coating Examples 12 to 22 and Comparative Examples 6 to 10 As shown in Table 3, the primer compositions of Examples and Comparative Examples obtained above were applied on mild steel plates (90 × 150 × 0.8 mm). 20 seconds in xylene (Ford Cup # 4/20
℃), spray-coated so as to have a dry film thickness of about 100 to 150 μm, and then “Prismarite”
(Cork, halogen lamp) irradiation distance 15c
m for 10 minutes to cure. After the obtained primer surface was lightly polished with # 600 water-resistant paper, "Rethane P
"G-80 White" (acrylic urethane resin top coat, manufactured by Kansai Paint Co., Ltd.) was spray-coated so as to have a dry film thickness of 50 μm, and dried at 60 ° C. for 30 minutes to obtain each coated plate. Table 4 shows the performance test results of each coated plate. Each test method is as follows.

(* 1) Tackiness: The tackiness of the surface of each coated plate was examined (○: good, Δ: slight tack on the surface,
X: There is considerable tack on the surface).

(* 2) Adhesion: A sticking tape adhesion test was performed (試 験: no peeling, Δ: partial peeling, ×: peeling all over).

(* 3) Abrasiveness: Primer coated surface is # 6
The sample was polished with water-resistant paper and the polished state was observed (（:
Good, Δ: slightly entangled, ×: considerably entangled).

(* 4) Finishing property: The finishing property of each coated plate was visually evaluated (目: good, Δ: slightly glossy on painted surface, ×: considerably glossy on painted surface).

(* 5) Water resistance: Each coated plate was immersed in tap water for 7 days, and the state of the coated surface (formation of blister) was observed.
Further, a sticking test was conducted on a goban-shaped tape. Painted surface condition (○: good, Δ: blisters partially generated, ×: blisters generated on entire surface), tapered tape attached (付 着: no peeling,
Δ: Partially peeled, ×: Peeled over the entire surface).

[0081]

[Table 4]

Production Examples 11 to 12 of Photocurable Putty Compositions Each composition was blended according to the composition shown in Table 1 below, added sequentially, and mixed and stirred to obtain each of the photocurable putty compositions (PT1).
(PT2) was obtained. (Note 6) "SP-1507": an acrylate group-containing epoxy resin manufactured by Showa Polymer Co., Ltd. (Note 7) "SP-5003": an acrylate group-containing epoxy resin manufactured by Showa Polymer Co., Ltd. (Note 8) N, N, N 2,4,6-pentamethylaniline:
Chain transfer agent

[0083]

[Table 5]

Coating Example 23 The putty composition (PT1) obtained in the above preparation example was applied to a mild steel plate (90 × 150 × 0.8 mm) with a spatula so as to have a thickness of 5 mm, and “Square Light” (Ushio Lighting) 2 at irradiation distance of 20 cm with a metal halide lamp
Irradiated for minutes. After lightly polishing the obtained putty surface, the primer composition (P1) obtained in the above preparation example was spray-coated so as to have a dry film thickness of about 50 to 100 μm,
Then, it was irradiated with a “square light” at an irradiation distance of 20 cm for 2 minutes to be cured. After the obtained primer surface was lightly polished with # 600 water-resistant paper, "Retan PG-80 White" (acrylic urethane resin-based overcoat, manufactured by Kansai Paint Co., Ltd.) was spray-coated so as to have a dry film thickness of 50 [mu] m. For 30 minutes to obtain a coated plate.

Example 24 The putty composition (PT2) obtained in the above-mentioned production example was applied to a mild steel plate (90 × 150 × 0.8 mm) with a spatula so as to have a thickness of 5 mm. The primer composition (P11) obtained in the above was spray-coated so as to have a dry film thickness of about 50 to 100 μm, and then “square light”
(Metal halide lamp manufactured by Ushio Lighting Co., Ltd.) for 2 minutes at an irradiation distance of 20 cm to cure both coating surfaces. Without polishing the obtained primer surface, "Rethane PG-80 White" (acrylic urethane resin-based top coat, manufactured by Kansai Paint Co., Ltd.) was spray-coated so as to have a dry film thickness of 50 μm, and dried at 60 ° C. for 30 minutes. To obtain a painted plate.

COMPARATIVE EXAMPLE 11 On a mild steel plate (90.times.150.times.0.8 mm), "LUC Poly Putty" (manufactured by Kansai Paint Co., Ltd., an unsaturated polyester resin room-temperature-curing two-pack type putty) was used immediately before use. 2% of "LUC putty common curing agent" (Kansai Paint Co., Ltd., organic peroxide compound) is blended, and this putty composition is applied with a spatula to a thickness of 5 mm and polished at 20 ° C. Dry until dry. Next, "JUST Urethane Prasaf" (Kansai Paint Co., Ltd., acrylic urethane resin 2
20% of "JUST urethane plasaf hardener" (manufactured by Kansai Paint Co., Ltd.) based on the liquid base material
"Retan PG2K Thinner" (Kansai Paint Co., Ltd.)
0%, and the primer composition has a dry film thickness of 50 to
It was spray-coated so as to have a thickness of about 100 μm, and was forcibly dried at 60 ° C. until polishing became possible. After the obtained primer surface was lightly polished with # 600 water-resistant paper, "Retan PG-80 White" (acrylic urethane resin-based overcoat, manufactured by Kansai Paint Co., Ltd.) was spray-coated so as to have a dry film thickness of 50 [mu] m. For 30 minutes to obtain a coated plate.

Table 6 shows the performance test results of the respective coated plates. Each test method is as follows. The adhesion is as described above (* 2).

(* 6) Total drying time: The total of light irradiation and heating time (minutes) in the putty and primer steps.

(* 7) Finishing property: In the process of preparing each coated plate, after applying the top coat paint, apply a lamp or force dry, then leave at 24 ° C. for 24 hours and visually observe the surface based on the following criteria. Evaluation was made (（: good, Δ: slight distortion on the coated surface, x: considerable distortion on the coated surface).

(* 8) Water resistance: After immersing each coated plate in tap water for 7 days, the state of the coated surface (the occurrence of blisters) was observed.
Further, a test similar to the above-mentioned adhesion test and a bending test were performed. In the bending test, each coated plate was bent at a 90 ° angle from the center, and the state of the bent portion was visually observed.

Painted surface condition (○: good, Δ: partial blister)
Occurrence, ×: blisters generated on the entire surface) Adhesion (○: no peeling, Δ: partial peeling, ×: entire surface peeled) Bending test (○: good, △: slight peeling, ×: peeling)

[0092]

[Table 6]

[0093]

According to the photo-curable primer composition of the present invention, the curing time is short in a one-pack type, the working efficiency is improved, and the curing does not proceed until irradiation with light, so that the usable time as a paint is long. Has features. Furthermore, when a specific polymerizable unsaturated group-containing resin is used, the resulting primer-coating film contains a large amount of urethane bonds, has excellent adhesion to the substrate and abrasion properties, and has excellent finish after applying a top coat. Is also excellent. In addition, using the composition of the present invention, wet-on-wet coating can be performed between the putty / primer layer, the process time can be further reduced, and the formed coating film has good curability. It has excellent adhesion between layers.

[Brief description of the drawings]

FIG. 1 shows a container for storing the photocurable primer composition of the present invention.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takao Matoba 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa F-term (reference) in Kansai Paint Co., Ltd. 4J038 CG001 CG002 DG211 DG212 DG261 DG262 EA012 FA002 FA042 FA122 FA152 FA212 FA231 FA232 FA252 FA262 FA272 FA281 FA282 GA01 HA286 HA376 HA446 HA486 HA526 HA536 HA546 KA03 KA06 MA02 NA23 PA17 PB07 PC02 PC06 PC08

Claims (9)

[Claims] (1) The resin (A) contains a polymerizable unsaturated group in a side chain via a urethane bond, and has a polymerizable unsaturated group.
Acrylic resin containing 0.2 to 2.0 mol / kg in solid content of (A), (B) urethane (meth) acrylate oligomer containing one or more polymerizable unsaturated groups in one molecule, (C)
A photocurable primer composition comprising: a polymerizable unsaturated compound; (D) extender pigment; and (E) a photopolymerization initiator. 2. An acrylic resin (A) obtained by reacting a hydroxyl group-containing acrylic resin (a) with a compound (b) having an isocyanate group and a polymerizable unsaturated group in one molecule. Item 4. A photocurable primer composition according to Item 1. 3. The acrylic resin (A) is obtained by reacting an isocyanate group-containing acrylic resin (c) with a compound (d) having a hydroxyl group and a polymerizable unsaturated group in one molecule. Item 4. A photocurable primer composition according to Item 1. 4. A urethane (meth) acrylate oligomer (B) comprising a compound (e) containing two or more isocyanate groups in one molecule, a hydroxyl-containing polymerizable unsaturated monomer (f), and The photocurable primer composition according to claim 1, which is obtained by reacting with a polyhydric alcohol (g). 5. The use ratio of the components (A), (B) and (C) is 5 to 5% based on the total solid content of the components.
5. The method according to claim 1, wherein the component (B) is 5 to 90% by weight, and the component (C) is 5 to 60% by weight.
Item 4. The photocurable primer composition according to item 1. 6. The photocurable primer composition according to claim 1, wherein resin particles are used in combination with the extender pigment (D). 7. The photocurable primer composition according to claim 1, which has a Ti value of 5 or more. 8. A photocurable putty composition is applied to a substrate surface, and then the photocurable primer composition according to any one of claims 1 to 7 is applied thereon. Painting method. 9. A coating layer of a photocurable putty composition and a coating layer of a photocurable primer composition formed on the coating surface are irradiated with light to cure both coating surfaces simultaneously. 9. The coating method according to claim 8, wherein the coating method is performed at least.