JP2002256220A - Curable composition for coating, multilayer curable coating film, coated article, outer plate for automobile and active energy ray curable composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a curable composition for coating capable of forming a coating film of top coating having excellent transparency, scratch resistance, chemical resistance, weather resistance and adhesivity to a substrate and a coating film of surface prearrangement on the surface of a substrate, applicable to an outer plate for automobiles especially in a three-dimensional shape, and contributing to the prevention of global warming. SOLUTION: This curable composition for coating comprises mixing 100 mass parts of the total of (A) 20-80 mass % of a polymer compound containing an acryloyloxy group on the side chain with (B) 2-60 mass % of a curable silicone (solid content) and (C) 5-50 mass % of an alicyclic compound group containing one or more acryloyloxy groups in one molecule and/or a heterocyclic compound group containing one or more acryloyloxy groups in one molecule with (D) 0.01-10 mass parts of a radical polymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to a novel composition, and more particularly, to a substrate surface having excellent transparency, abrasion resistance, heat resistance, chemical resistance, weather resistance, and a base coat. A curable composition for coating capable of forming a topcoat film having excellent adhesion, a multilayer cured film having a clear top coat film containing the composition as a main component, a coated article having a cured film of the composition, And an active energy ray-curable composition in which a coating film formed on a substrate before polymerization and curing becomes tack-free.

[0002]

2. Description of the Related Art Conventionally, a coating material for top coating such as an automobile outer panel has been mainly of a type in which a hydroxyl group-containing acrylic resin is cured by heating with a melamine resin. However, in recent years, etching and stain-like stains on paint films due to acid rain and abrasions during car washing due to the spread of car washing machines have been taken up around the world, so sufficient acid rain resistance and abrasion resistance have been simultaneously achieved. There is a need for a satisfactory topcoat paint.

On the other hand, the problem of preventing global warming has been taken up on a worldwide scale. In particular, most of the outer skin paints for automobiles, which are used in enormous amounts, are thermosetting paints. Therefore, when the paint is heated and baked, there is a problem that carbon dioxide is generated and global warming is accelerated.

[0004] Under such a problem, Japanese Patent Laid-Open Publication No.
No. 5770 discloses that the above-described acid rain resistance and abrasion resistance are achieved by using a polymer having a carboxyl group and a hydroxyl group in the molecule and a polymer having an epoxy group and a hydroxyl group in the molecule as a top coat by heat curing. Methods have been proposed to simultaneously satisfy the overcoming. Further, Japanese Patent Application Laid-Open No. 5-59326 discloses that a coating film having excellent acid rain resistance can be obtained by using both crosslinking with an amino resin and crosslinking with a blocked isocyanate.

[0005] However, these methods can improve the performance of the coating film itself, but require a large amount of electricity at the time of heating because the coating is a heat-curable coating material. Emissions cannot be controlled and cannot contribute to the prevention of global warming.

[0006] Among the performances required for the outer panel of an automobile, the scratch resistance has been limited as the industry standard has become higher in the case of a coating film composed of only an organic material. for that reason,
In the case of transparent synthetic resin molded products that emphasize this, as a method for improving scratch resistance, for example, a paint composed of a partially hydrolyzed condensate of a silane mixture containing alkyltrialkoxysilane as a main component and colloidal silica is used. A method of applying to the surface and then heat-treating to form a cross-linked coating to improve the scratch resistance (US Pat. No. 4,060,271)
No.) has been found.

[0007] Although this method can provide a coating having high abrasion resistance, it is a heat-curable coating, so that the curing time is long and thermal energy is required during curing, so that the amount of carbon dioxide emitted is low. Has no effect on the reduction of Further, it is difficult to form this coating film on the colored undercoating film.

As a technique effective for reducing the abrasion resistance and carbon dioxide emission, Japanese Patent Publication No. 57-500984 (US Pat. No. 4,438,462) discloses colloidal silica and a methacryloyloxy group. A method is disclosed in which an ultraviolet-curable coating composed of an alkoxysilane having a glycidyl functional group and a non-silyl acrylate is applied to the surface of a molded product, and then irradiated with ultraviolet light to obtain a scratch-resistant synthetic resin molded product. . According to this method, the curing time of the conventional silicon-based coating film is significantly reduced by using an ultraviolet-curable coating material, and the scratch resistance of the coating film can be improved.

[0009] However, this method can be applied to a substrate having a three-dimensional shape such as an automobile outer panel, although it can be applied to a substrate having a simple shape. That is, in order to coat a substrate having a three-dimensional shape, it is necessary that the paint does not sag after being applied to the substrate, and a tack-free coating film is required. Even after the organic solvent is volatilized, dripping occurs in a liquid state, a film having tackiness even when the liquid state becomes highly viscous, and the like, disadvantages occur, and the ultraviolet curable paint also At present, it cannot be used for automotive skins.

[0010]

The inventors of the present invention have made intensive studies on the above problems and found that colloidal silica capable of imparting abrasion resistance to a coating film and a radical polymerizable silane compound under specific conditions. Curable silicon obtained by reacting under, and after the contained organic solvent is volatilized, a tack-free coating film is obtained, a polymer compound having a radical polymerizable functional group in the molecule, toughness and advanced Attention was paid to using together with an ethylenically unsaturated compound capable of imparting chemical resistance such as sulfuric acid resistance and solvent resistance.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to (A) a polymer compound having an acryloyloxy group in a side chain of 20 to 80% by mass,
(B) (b1) Colloidal silica fine particles (solid content) 40 to 9
0 mass%, and (b2) the following general formula (I)

Embedded image

(Wherein X represents a methacryloyloxy group, an acryloyloxy group or a vinyloxy group, R ¹ represents a linear or branched alkyl group having 0 to 8 carbon atoms,
R ² and R ^{3 each} represent a linear or branched alkyl group having 1 to 8 carbon atoms, n represents a positive integer of 0 to 2, and m + n represents a positive number of 1 to 3. )) Or a hydrolyzate (solid content) of 10 to 60% by mass (provided that the total amount of component (b1) and component (b2) is 100 parts by mass) (C) one or more alicyclic compounds having one or more acryloyloxy groups in one molecule and / or one or more in one molecule. Curable composition for coating comprising (D) 0.01 to 10 parts by mass of a radical polymerization initiator, based on 100 parts by mass of the total of 5 to 50% by mass of the heterocyclic compound group having an acryloyloxy group; In the method for forming a top coat by sequentially forming a colored base coat film and one or more layers of a clear top coat film on a substrate, the outermost clear top coat film is a curable composition for coating according to claims 1 to 3. Composition as the main component Multilayer cured coating, the coated article, and the automotive outer panels having a multilayer cured coating film having a cured coating film of the coating curable composition.

First, the curable composition for coating of the present invention will be described in detail.

The curable composition for coating of the present invention (hereinafter abbreviated as coating composition) comprises (A) 20 to 80% by mass of a polymer compound having an acryloyloxy group in a side chain, (B) (b1)
Colloidal silica fine particles (solid content) 40 to 90% by mass
And (b2) the following general formula (I)

Embedded image (Wherein, X represents a methacryloyloxy group, an acryloyloxy group, or a vinyloxy group, and R ¹ has 0 to 8 carbon atoms.
R ² and R ^{3 each} represent a linear or branched alkyl group having 1 to 8 carbon atoms, n represents a positive integer of 0 to 2, and m + n represents a positive integer of 1 to 3 Is a number. ) Or a hydrolyzate thereof (solid content)
60% by mass (however, the total amount of the component (b1) and the component (b2) is 1
A) an alicyclic compound having at least one acryloyloxy group in one molecule (C) 2 to 60% by mass of curable silicon (solid content) obtained by hydrolysis and condensation reaction Group and / or heterocyclic compound group 5 having one or more acryloyloxy groups in one molecule
It is a composition comprising (D) 0.01 to 10 parts by mass of a radical polymerization initiator with respect to 100 parts by mass in total of 50 to 50% by mass.

Hereinafter, each component of the coating composition will be described.

The component (A) of the present invention is a polymer compound having an acryloyloxy group in a side chain, and is a component for imparting flexibility.

As a specific example of the component (A), for example, a copolymer composed of a vinyl monomer having an acid anhydride group such as maleic anhydride and itaconic anhydride and another copolymerizable monomer is synthesized. A polymer compound obtained by adding an acrylate monomer having a hydroxyl group such as hydroxyalkyl acrylate to an acid anhydride group in a polymer chain;
After synthesizing a copolymer composed of a vinyl monomer having a carboxyl group such as acrylic acid and methacrylic acid and other copolymerizable monomers, an acrylate monomer having an epoxy group such as glycidyl acrylate in the carboxyl group in the polymer chain After synthesizing a copolymer composed of a vinyl monomer having an epoxy group such as glycidyl (meth) acrylate and other copolymerizable monomers, acrylic acid or the like is added to the epoxy group in the polymer. And a polymer compound obtained by adding an acrylate monomer having a carboxyl group.

These addition reactions may be carried out by a usual method, and can be carried out at a temperature of from room temperature to about 80 ° C., and if necessary, using a tertiary amine or the like as a catalyst.

Other monomers copolymerizable with a vinyl monomer having an acid anhydride group, a vinyl monomer having a carboxyl group, a vinyl monomer having an epoxy group, and the like include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, Butyl (meth) acrylate,
2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dicyclopentanyl (meth) acrylate, (Meth) acrylic acid esters such as cyclopentenyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, (meth) acrylamide, N-butoxy (meth) acrylamide and the like (Meth) acrylamides, styrene, α-methylstyrene, vinyl compounds such as vinyl toluene and vinyl acetate, glycerin monoallyl ether, allyl alcohol, ethylene glycol monoallyl And allyl ether alcohol compounds such as ether.

In order to make the most of the properties of the coating composition of the present invention, it is necessary to pay attention so that unadded acid anhydride groups and carboxyl groups remain as little as possible in the polymer compound (A). When a large amount of an acid anhydride group or a carboxyl group remains without being added, the resulting cured coating film tends to have poor solvent resistance and weather resistance.

The molecular weight of the polymer compound (A) may be appropriately selected depending on the mixing ratio of the components (B) and (C) described below, and is not particularly limited.
Range of about 00 to 50,000, especially 2000 to 1000
A range of about 0 is preferable.

The polymer (A) has a weight average molecular weight of 1
If it is smaller than about 000, the coating film performance after curing tends to decrease, and if it is larger than about 50,000, the compatibility of the composition tends to decrease.

The amount of the polymer compound (A) used in the coating composition of the present invention is 10% in total of the components (A) to (C).
In 0 parts by mass, a range of 20 to 80% by mass, preferably 30% by mass.
The range is from 75 to 75% by mass, and more preferably from 40 to 70% by mass. If the amount of the polymer compound (A) is less than 20% by mass, the flexibility of the cured coating film is extremely lowered and cracks tend to occur. Chemical properties, surface hardness, abrasion resistance, and weather resistance tend to decrease.

The component (B) of the present invention comprises (b1) 40 to 90% by mass of colloidal silica fine particles (solid content) and (b2) the following general formula (I)

Embedded image (Wherein, X represents a methacryloyloxy group, an acryloyloxy group, or a vinyloxy group, and R ¹ has 0 to 8 carbon atoms.
R ² and R ^{3 each} represent a linear or branched alkyl group having 1 to 8 carbon atoms, n represents a positive integer of 0 to 2, and m + n represents a positive integer of 1 to 3 Is a number. ) Or a hydrolyzate thereof (solid content)
60% by mass (however, the total amount of the component (b1) and the component (b2) is 1
Is a curable silicone obtained by hydrolysis and condensation reaction.

The curable silicone (B) is a component that imparts abrasion resistance to the cured coating film.

In the coating composition of the present invention, the colloidal silica fine particles (b1) as a component of the component (B) are:
It refers to a state in which ultrafine particles of silicic anhydride having a primary particle diameter of 1 to 200 nm are dispersed in a dispersion medium of water or an organic solvent.

Examples of the dispersion medium include water; alcohol solvents such as methanol, ethanol, isopropanol, n-propanol, isobutanol and n-butanol; polyhydric alcohol solvents such as ethylene glycol; ethylene cellosolve; Polyhydric alcohol derivatives such as butyl cellosolve; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and diacetone alcohol;
Examples thereof include monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and tetrahydrofurfuryl acrylate.

Of these, alcohol solvents having 3 or less carbon atoms are particularly preferred in the reaction step with the component (b2) described below. The colloidal silica fine particles (b1) can be produced by a known method, and are also commercially available.

The colloidal silica fine particles (b1) are components that can significantly improve the scratch resistance of the cured coating film, and are particularly excellent in improving the scratch resistance of fine particles such as silica sand. However, when the colloidal silica fine particles alone are used as a cured coating film, the adhesion to the substrate is poor.

The average particle size of the fine particles of the colloidal silica (b1) used in the coating composition of the present invention is not particularly limited, but is preferably in the range of 1 to 200 nm, particularly preferably in the range of 5 to 80 nm. If the average particle diameter is smaller than 1 nm, gelation tends to occur in the reaction step with the component (b2) described later, and if it exceeds 200 nm, the transparency of the cured coating film tends to decrease.

The monomer (hereinafter abbreviated as a silane compound) or its hydrolyzate represented by the general formula (I), which is the component (b2), reacts with the colloidal silica fine particles (b1) to produce a polymer compound ( A component that improves the compatibility between A) and compound (C).

As the component (b2), a silane compound having an acryloyloxy group, a methacryloyloxy group, or a vinyl group or a styryl group, which exhibits polymerization activity upon irradiation with ultraviolet light, is used. It is possible to form a chemical bond between (A) and the compound (C), thereby providing the cured coating with adhesion to the synthetic resin molding surface.

Further, when used in combination with the colloidal silica fine particles (b1), the scratch resistance of the cured coating film can be further improved, and in particular, the effect of improving the scratch resistance of metal fibers such as steel wool can be enhanced. it can.

As a specific example of the component (b2), for example, 3-
Methacryloyloxypropyltrimethoxysilane, 3
Acryloyloxypropyltrimethoxysilane, 2
-Methacryloyloxyethyltrimethoxysilane, 2
-Acryloyloxyethyltrimethoxysilane, 3-
Methacryloyloxypropyltriethoxysilane, 3
Acryloyloxypropyltriethoxysilane, 2
-Methacryloyloxyethyltrimethoxysilane, 2
-Acryloyloxyethyltrimethoxysilane, 3-
Examples include at least one silane compound selected from methacryloyloxypropylmethyldimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and the like, or a hydrolyzate thereof.

Among the above, 3-methacryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane At least one silane compound selected from silanes or a hydrolyzate thereof is particularly preferred.

The hydrolysis is carried out in the presence or absence of an organic solvent such as an alcohol solvent in the presence or absence of 0.5 to 6 mol of water or 0.001 mol of silane compound per mol.
A first step of adding a hydrolysis catalyst such as an aqueous solution of 0.1N hydrochloric acid or acetic acid and stirring the mixture under heating to remove the alcohol produced by the hydrolysis out of the system; It can be obtained by performing a second step of removing outside.

Here, the method for producing the component (B) in the present invention will be described in detail below.

The method for producing the component (B) is carried out in the presence of colloidal silica fine particles (b1) and a hydrolyzate of a silane compound (b2).
The azeotropic distillation of the dispersion medium in the colloidal silica fine particles (b1) with a nonpolar solvent such as toluene under normal pressure or reduced pressure,
After replacing the dispersion medium with a non-polar solvent, the reaction is carried out under heating.

Specifically, first, colloidal silica fine particles
A hydrolysis catalyst is added to (b1) and the silane compound (b2), and the silane compound is hydrolyzed by an ordinary method such as stirring at room temperature or under heating. Next, colloidal silica fine particles (b1)
The dispersion medium in the mixture is azeotropically distilled together with the non-polar solvent under normal pressure or reduced pressure, and after replacing the dispersion medium with the non-polar solvent,
In a temperature range of 150 ° C, preferably 80 to 130 ° C, the solid content concentration is in a range of 30 to 90% by mass, preferably 50 to 90% by mass.
The mixture is stirred for 0.5 to 10 hours while maintaining it in the range of 80% by mass. During this reaction, water,
A catalyst such as an acid or a base may be used.

The curable silicon (B) obtained in this manner was hydrophobized by coating the surface of the hydrophilic colloidal silica fine particles (b1) with (meth) acryloyl-functional silicon, and thus was used in the present invention. Polymer compound (A)
And the compound (C) are improved in compatibility, and the resulting cured coating film has good transparency. In particular, when the cured coating film of the composition of the present invention is made thick, the haze value of the coating film becomes very small, and the appearance as a clear top coat film tends to be excellent.

The non-polar solvent used in the production of the component (B) may be appropriately selected based on the dielectric constant, dipole moment or hydrogen bonding parameter, and has a medium polarity in a broad sense. The solvent is also included in the non-polar solvent referred to herein. For example, the dielectric constant at 20 ° C. is 2
A non-polar solvent in the range of 10 is a preferred solvent when producing the component (B).

Specific examples of the non-polar solvent include, for example, hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cyclohexane; halogenated hydrocarbons such as trichloroethylene and tetrachloroethylene; 1,4-dioxane; Ethers such as butyl ether; ketones such as methyl isobutyl ketone; esters such as n-butyl acetate, isobutyl acetate, ethyl acetate and ethyl propionate; polyhydric alcohols such as 1-methoxy-2-propanol and ethylene glycol monobutyl ether Derivatives and the like can be mentioned.

Further, unsaturated ethylenic compounds such as 1
Monomers having one or more (meth) acryloyloxy groups in the molecule can also be used as the non-polar solvent. Among these nonpolar solvents, the use of aromatic hydrocarbons or polyhydric alcohol derivatives is preferred from the viewpoint of the reaction between the component (b1) and the component (b2), and toluene and 1-methoxy-2-propanol are particularly preferable. preferable.

During the production of the component (B), it is preferable to keep the concentration of solids in the reaction system constant, especially 30 to 9
A range of 0% by mass is preferred. When the solid content is less than 30% by mass, that is, when the amount of the solvent exceeds 70% by mass, the reaction between the components (b1) and (b2) tends to be insufficient. Tends to have poor transparency. On the other hand, if this solid content concentration exceeds 90% by mass, a rapid reaction occurs and the gelation tends to occur.

The component (B) in the present invention comprises the component (b1)
The component (b2) is (b1) / (b2) = 40-90 / 10-6 in a mass ratio.
It is obtained by reacting at a use ratio of 0, preferably 50 to 80/20 to 50 (total 100 parts by mass).

When the use ratio of the component (b1) and the component (b2) is out of the above range, for example, when the component (b1) exceeds 90% by mass, the reaction system tends to become cloudy or gel. Cracks tend to occur in the cured coating film.

On the other hand, when the component (b1) is less than 40% by mass, (b)
The reaction between component 1) and component (b2) tends to be insufficient,
Further, when a thick cured coating film is formed, the scratch resistance and transparency of the coating film tend to decrease.

The curable silicon produced by such a conventional method other than the present invention has insufficient curability, cannot be cured sufficiently in an air atmosphere, and tends to cause appearance defects such as a decrease in transparency. It is in. In addition, the problem that sufficient scratch resistance and weather resistance etc. of the cured coating film could not be obtained, the present invention,
By reacting the component (b1) and the component (b2) in a non-polar solvent, an unprecedented excellent curability is realized, and a cured coating film which is transparent and has excellent scratch resistance even in an air atmosphere. This enables formation.

The amount of the curable silicon (B) used in the coating composition of the present invention is 1 in total of the components (A) to (C).
In the range of 2 to 60% by mass, preferably 10 to 100% by mass.
The range is from 50 to 50% by mass, and more preferably from 15 to 40% by mass.

2% by mass of curable silicone (B)
If the amount is smaller, the surface tackiness becomes poor, and the effect of improving the scratch resistance tends not to be sufficiently exhibited.
If it exceeds 0% by mass, the coating film appearance, chemical resistance, scratch resistance,
Surface hardness, weather resistance, and adhesion are poor, and cracks tend to occur in the cured coating film.

The component (C) of the present invention is a group of alicyclic compounds having one or more acryloyloxy groups in one molecule and / or heterocyclic compounds having one or more acryloyloxy groups in one molecule. It is a group and is a component that imparts high toughness and chemical resistance such as sulfuric acid resistance and solvent resistance to a coating film.

Specific examples of the component (C) of the present invention include, for example, a heterocyclic compound having one acryloyloxy group such as tetrahydrofurfuryl acrylate, acryloyl morpholine, morpholinoethyl acrylate, isobornyl acrylate, Cyclohexyl acrylate, 2-cyclohexylethyl acrylate, 4-
Alicyclic compounds having one acryloyloxy group such as cyclohexylcyclohexyl acrylate, methylcyclohexyl acrylate, trimethylcyclohexyl acrylate, adamantyl acrylate, and tricyclodecanyl acrylate; 1,4-dimethylolcyclohexanediacrylate; tricyclodecanedimethanol Acrylate, 2,2-bis (4-acryloyloxycyclohexyl) propane, 2,2-bis (4- (acryloyloxydiethoxy) cyclohexyl) propane, 2,2-bis (4- (acryloyloxydipropoxy) cyclohexyl) An alicyclic compound having two acryloyloxy groups such as propane can be exemplified. These compounds may be used alone or in combination of two or more, but it is particularly preferable to use two or more in combination.

Of the above, 1,4-dimethylolcyclohexane diacrylate and tricyclodecane dimethanol diacrylate are particularly preferred.

In the present invention, the amount of compound (C) used is
5 to 50 in 100 parts by mass of the total amount of components (A) to (C)
%, Preferably in the range of 10 to 30% by weight. If the amount of the compound (C) is less than 5% by mass, the weather resistance of the obtained cured coating film and the adhesion to the substrate tend to decrease, while if it exceeds 50% by mass, cracks occur in the cured coating film. Or the tack-free property tends to decrease.

(D) Component The radical polymerization initiator (D) is added to the coating composition of the present invention.
Is blended. The radical polymerization initiator (D) may be any compound that generates a radical, and may be a compound that generates a radical by an active energy ray or a compound that generates a radical by heat.

Among the specific examples of the component (D), specific examples of the compound that generates a radical by an active energy ray include benzoin, benzoin methyl ether,
Benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, methylphenylglyoxy Rate, ethylphenylglyoxylate, 4,
4-bis (dimethylaminobenzophenone), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 1
-(4-isopropylphenyl) -2-hydroxy-2
Carbonyl compounds such as -methylpropan-1-one; sulfur compounds such as tetramethylthiuram disulfide; azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile; benzoyl peroxide and ditertiary butyl par Peroxide compounds such as oxides; acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide.

Specific examples of the compound that generates a radical by heat include benzoyl peroxide, t-butylperoxy-2-ethylhexanate, bis (4-t-
(Butylcyclohexyl) peroxydicarbonate, cumene hydroperoxide, methyl ethyl ketone peroxide and the like.

Among the radical polymerization initiators (D), in the present invention, at least one compound selected from benzophenone, 1-hydroxycyclohexylphenyl ketone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide methylphenylglyoxylate is used. Particularly preferred.
In the present invention, if necessary, a compound capable of generating a radical by an active energy ray and a compound capable of generating a radical by heat may be used in combination.

In the present invention, the radical polymerization initiator (D)
Is used in a range of 0.01 to 10 parts by mass with respect to a total of 100 parts by mass of the components (A) to (C) of the coating composition.
Preferably it is in the range of 0.1 to 5 parts by mass.

The amount of the radical polymerization initiator (D) used is 0.
If the amount is less than 01 parts by mass, poor curing tends to occur, while if it exceeds 10 parts by mass, the cured coating film tends to be colored and the weather resistance tends to decrease.

Component (E) The coating composition of the present invention may optionally contain an organic solvent (E).

Specific examples of the organic solvent (E) include, for example, alcohol solvents such as isopropyl alcohol, n-butanol, isobutanol and diacetone alcohol; hexane, cyclohexane, toluene, xylene,
Hydrocarbon solvents such as high boiling aromatic solvents such as Swazol 1000 (trade name, manufactured by Maruzen Petrochemical Co.); methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone;
Ketone solvents such as cyclohexanone; ether solvents such as ethyl ether; ester solvents such as ethyl acetate, n-butyl acetate, amyl acetate, methoxypropyl acetate and ethoxyethyl acetate; methyl cellosolve, ethyl cellosolve, butyl cellosolve, methoxypropanol; Examples include solvents based on polyhydric alcohol derivatives such as methoxybutanol and ethyldiglycol.

These organic solvents (E) may be used in various aspects such as uniform solubility and dispersion stability of the composition of the present invention, adhesion of the cured coating film to a substrate, smoothness and uniformity, and the like. It may be appropriately selected and used from the viewpoint of appropriately adjusting the viscosity from the viewpoint of improving workability during coating, and may be used alone or in combination of two or more.

When the composition of the present invention is used as a top coat, it is preferable to use an organic solvent (E). Particularly preferred specific examples include organic solvent (E) 10
When the content is 0% by mass, the alcoholic organic solvent (e1) 0
30 mass%, acetate organic solvent (e2) 0-30 mass%, ketone solvent (e3) 1-30 mass%, polyhydric alcohol derivative solvent (e4) 1-30 mass%, aromatic solvent ( e5) a combination of 1 to 30% by mass.

When the organic solvent (E) is used in the present invention, it is preferably in the range of 10 to 1000 parts by weight, particularly preferably 50 to 100 parts by weight, based on the total amount of the components (A) to (C). ８００800 parts by mass.

When the amount of the organic solvent (E) exceeds 1000 parts by mass, there is a possibility that a long time is required for volatilization of the solvent and that the workability is lowered such that sagging is apt to occur during coating.

The coating composition of the present invention may contain, if necessary, an antioxidant, an anti-yellowing agent, a bluing agent, a pigment, a leveling agent, an antifoaming agent, a thickener, an anti-settling agent, Various additives such as an antistatic agent, an antifogging agent, an ultraviolet absorber, and a light stabilizer may be contained.

Next, the multilayer cured coating film and coated article of the present invention will be described in detail below.

In order to form a coating film in the present invention, the coating composition is first applied by a brush coating method, a spray coating method,
What is necessary is just to apply to a base material by well-known methods, such as a shower flow coating method, a dip coating method, and a curtain coating method.

The coating amount of the coating composition may be appropriately determined, but is preferably in the range of 5 to 80 μm, more preferably in the range of 10 to 60 μm, and still more preferably in the range of 20 to 50 μm. If so, a cured coating film having sufficient abrasion resistance and adhesion to the substrate is obtained, and the durability due to the curing shrinkage is excellent.

Means for curing the coating film of the coating composition may be performed by a known method, and is not particularly limited. For example,
Irradiation with active energy rays such as α, β, and γ rays is preferable, and among them, it is preferable to use ultraviolet rays, which are versatile, low-cost, and have high productivity.

As an ultraviolet source, an ultraviolet lamp is generally used in terms of practicality and economy. Specific examples include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, and a metal halide lamp. The atmosphere for irradiating these may be air or an inert gas such as nitrogen or argon. An air atmosphere is preferable from the viewpoint of practicality and economy.

When the coating composition is applied to a substrate and before it is cured with an active energy ray or the like, if an organic solvent is used, it is volatilized and removed from the coating film. This volatilization may be performed at room temperature as it is,
Infrared or hot air drying oven at 20-120 ° C
The heat treatment may be performed for up to 60 minutes.

The substrate on which the multilayer cured film of the present invention is applied is not particularly limited, and various types of substrates may be used. A plastic substrate (a surface which has been subjected to a surface treatment such as primer coating or intermediate coating if necessary, or a composite member obtained by combining these materials) may be used.

Specific examples of the plastic substrate include:
For example, polymethyl methacrylic resin, polycarbonate resin, polyester resin, polyolefin resin, acrylonitrile-styrene copolymer resin, polyamide resin, polyarylate resin, polymethacrylimide resin and the like can be mentioned.

The coated article of the present invention is an article having a cured coating film of the coating composition. The article here means
Other than the above-described base material, there is no particular limitation on glass, metal, wood, paper, cloth, and the like. In particular, articles having a cured coating film of the coating composition of the present invention are particularly suitable for automobile outer panels.

A specific method of manufacturing an automobile outer panel will be specifically described below.

This formation method is a method in which a base coat film is formed on a substrate with a thermosetting colored paint and then a clear top coat film is formed with the composition of the present invention, or a thermoset colored paint is formed on the substrate. After forming a base coat film and a thermosetting clear coat film of melamine type or acid-epoxy type, a method of forming a clear top coat film with the composition of the present invention can be applied.

Specific examples of the thermosetting coloring paint include acrylic resin / amino resin, alkyd resin / amino resin, polyester resin / amino resin, acrylic resin / polyisocyanate, and alkyd resin / polyisocyanate. A coating composition in which a coloring pigment is blended with a known resin composition such as a resin, a polyester resin / polyisocyanate, an epoxy acrylic resin / a carboxylic acid acrylic resin, or the like.

The form of the thermosetting colored paint may be any form such as an organic solvent type, a high solid type, a non-dispersed type, an aqueous solution type, and a water dispersed type. However, from the viewpoint of suppressing the amount of solvent discharged at the time of forming the coating film, it is preferable to form the colored base coat film with a water-containing thermosetting coloring paint.

After forming the base coat film, the clear top coat film of the present invention may be formed. However, after forming a melamine type or acid-epoxy type thermosetting clear coat film as an intermediate coating clear, The clear top coat film of the present invention may be formed.

According to the present invention, by forming a coating composition comprising such components, the coating composition is applied to a substrate and then, when the organic solvent is contained, the contained organic solvent is volatilized. It was found that the coating film became tack-free, and that this coating film was polymerized and cured by irradiation with active energy rays.

By using such a composition, even when coating on a substrate having a three-dimensional shape, which has been difficult in the past, no dripping of the paint occurs during the coating operation, and the organic solvent is removed after coating. When it is contained, after volatilizing it, the coating film becomes tack-free and workability can be improved. In particular, the composition can be put to practical use as a clear coat film for an automobile outer panel. This can cure at the same time by irradiation with active energy rays and can solve the problem of global warming prevention with good productivity in a short time.

[0084]

The present invention will be described in more detail with reference to the following examples. In addition, the evaluation method in an Example is as follows.

1. Surface tackiness: A test plate having a coating film of the curable composition for coating formed on a substrate was heated at 120 ° C. for 10 minutes to volatilize an organic solvent in the coating film. Thereafter, the surface of the coating film naturally cooled to room temperature was touched by hand to evaluate the presence or absence of stickiness. ○: No surface tack ×: Surface tack

2. Coating appearance: The appearance of the cured coating was visually evaluated. ：: The cured coating has no abnormality and is excellent in smoothness. X: The surface of the cured coating has a skin-like or considerable unevenness and is poor in smoothness.

3. Sulfuric acid resistance: about 0.3m of 40% sulfuric acid solution
1 was dropped on the surface of the cured coating film, heated at 80 ° C. for 25 minutes, washed with water, and the coating film was visually evaluated. ：: No change x: The cured coating film surface was etched or yellowed.

4. Solvent resistance: A gauze sufficiently impregnated with methyl ethyl ketone and xylene was reciprocated 50 times under a load of 500 g, and the appearance of the coating film surface was visually evaluated. ：: No change Δ: Scratch or cloudy coating ×: Swelling or dissolution of coating

5. Scratch resistance: The felt impregnated with the cleanser was reciprocated 20 times with a load of 500 g. Then, the light reflectance was measured with a gloss meter (trade name: Gloss Meter VG2000, manufactured by Nippon Denshoku Industries Co., Ltd.), and the gloss retention of the cured coating film was calculated from the initial gloss and the gloss of the scratches. The gloss retention of 40% or more is indicated as abrasion resistance pass (O).

6. Pencil hardness: The pencil hardness of the cured coating film was measured in accordance with JIS K 5400 (Mitsubishi Pencil Co., Ltd., trade name Uni). Note that a pencil hardness of H or more is indicated as a pencil hardness pass (（).

7. Weather resistance: After the test plate was tested for 1000 hours with a sunshine weatherometer, the coating film surface was visually observed. ：: No change in coating film surface ×: Abnormality such as crack, discoloration, peeling, etc.

8. Adhesion: 100 grids are formed on the coating film with a cutter, and cellophane tape (Nichiban)
And peeled off at once.も の indicates that the coating film was not peeled off, and x indicates that the coating film was partially peeled off.

<Preparation of Polymer Compound> Synthesis Example 1 108 parts by mass of glycidyl methacrylate, 150 parts by mass of cyclohexyl methacrylate, isobutyl methacrylate 4
A mixed solution (a1) of 2 parts by mass and 21 parts by mass of azobisisobutyronitrile was prepared. Next, n-butyl acetate 21 was placed in a 2 liter four-necked flask equipped with a stirrer and a condenser.
0 parts by mass and 90 parts by mass of propylene glycol monomethyl ether acetate were charged.
After the temperature was raised to 0 ° C, the mixed solution (a1) was added dropwise over 4 hours to cause a stirring reaction, and 3 parts by mass of azobisisobutyronitrile was dissolved in 60 parts by mass of n-butyl acetate for 1 hour. The solution was dropped. Further, at 80 ° C., 6 parts by mass of tetramethylammonium bromide, 57 parts by mass of acrylic acid, and propylene glycol monomethyl ether acetate 30
After the mixture of parts by mass was added dropwise over 1 hour and stirred, the reaction was terminated when it was confirmed that the acid value was 5 mgKOH / g or less. Thus, the polymer compound (A1) was added to 46
A solution containing% by mass was obtained. Obtained polymer compound (A1)
Had a weight average molecular weight of about 6,000.

Synthesis Example 2 A mixed solution (a2) was prepared in the same manner as in Synthesis Example 1. Next, 210 parts by mass of n-butyl acetate and 90 parts by mass of propylene glycol monomethyl ether acetate were charged into a two-liter four-necked flask equipped with a stirrer and a condenser, and heated to 120 ° C. while purging with nitrogen. After (a2) was added dropwise over 4 hours to cause a stirring reaction, a solution prepared by dissolving 3 parts by mass of azobisisobutyronitrile in 60 parts by mass of n-butyl acetate was added dropwise over 1 hour. Further, a mixture of 6 parts by mass of tetramethylammonium bromide, 66 parts by mass of methacrylic acid, and 30 parts by mass of propylene glycol monomethyl ether acetate was dropped at 80 ° C. over 1 hour and stirred, and the acid value became 5 mgKOH / g or less. After confirming that the reaction was completed. Thus, a solution containing the polymer compound (A2) at 48% by mass was obtained. The weight average molecular weight of the obtained polymer compound (A2) was about 6,000.

<Synthesis of Curable Silicon> Synthesis Example 3 γ-methacryloyloxypropyltrimethoxysilane (trade name: KBM503, manufactured by Shin-Etsu Silicone Co., Ltd.) was placed in a 3-liter four-necked flask equipped with a stirrer and a condenser.
82 parts by mass, 2000 parts by mass of isopropanol-dispersed colloidal silica (SiO ₂ concentration: 30% by mass, trade name: IPA-ST, manufactured by Nissan Chemical Industries, Ltd.) and 0.038 parts by mass of hydroquinone monomethyl ether were charged, and heated to 80 ° C.
When the reflux started, 139 parts by mass of ion-exchanged water was dropped over 20 minutes. After the completion of the dropwise addition, the volatile components were distilled off over 2 hours, and the distilled components were 1204 parts by mass. Thereafter, the temperature of the reaction system is raised, and while stirring and refluxing, 1 hour.
The reaction was performed at 10 ° C. for 4 hours. The obtained reaction product (B1) was a light brown transparent solution having a solid content of 60% by mass.

Example 1 <Preparation of coating composition> 130 parts by mass (solid content 46% by mass) of a solution containing the polymer compound (A1) as the component (A),
Solution (B1) 17 containing curable silicon as component (B)
Parts by mass (solid content 60% by mass), tricyclodecane dimethanol diacrylate (trade name: Light Acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.) as the component (C) (C
1) 30 parts by mass, 2 parts by mass of 1-hydroxycyclohexylphenyl ketone (D1) (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) as a component (D) and methylphenylglyoxylate (D2) (trade name:
(Vicure 55, manufactured by Stoffer Co., Ltd.) was stirred and mixed to prepare a coating composition.

<Preparation of Evaluation Test Plate> Zinc phosphate treatment
Electrodeposition paint for automobiles on steel sheet (10cm x 30cm)
And baked at 180 ° C for 30 minutes.
Apply a liquid intermediate paint and bake at 160 ° C for 30 minutes
After the coating, the coating film was ground with water to obtain a dried plate. This
Each of the coating compositions shown in Table 1 was applied to
After drying at 5 ° C for 5 minutes, a high-pressure mercury lamp
3000mJ / cm ²(Wavelength 3
20 to 380 nm UV energy)
Test plate having 35 μm thick cured coating film
Got.

Examples 1 to 5 and Comparative Examples 1 to 9 Coating compositions were prepared in the same manner as in Example 1 except that the compositions shown in Table 1 were used. Thereafter, an evaluation test plate was prepared by the method described above, and the cured coating film was evaluated. The evaluation results of the cured coating film are also shown in Table 1.

[0099]

[Table 1]

The numerical values in the composition column in the table are all parts by mass, and the polymer compound (A) and the photocurable organic silicon were used.
Each numerical value of (B1) is a solid content (parts by mass). Also,
The numerical value of the organic solvent (D) is the total amount of the organic solvent contained in the solutions described in Synthesis Examples 1 to 4 and the amount of the organic solvent added alone.

The abbreviations in the table represent the following compounds. (A) Component (A1): Polymer compound polymerized in Synthesis Example 1 (solid content) (A2): Polymer compound polymerized in Synthesis Example 2 (solid content) (B) Component (B1): Synthesis Example 3 Synthesized photocurable organic silicon (solid content) (C) component (C1): tricyclodecane dimethanol diacrylate (trade name: light acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.) (C2): isobornyl acrylate ( Product Name: IBX
A, manufactured by Osaka Organic Chemical Industry Co., Ltd.) (C3): 1,6-hexanediol dimethacrylate (trade name: NK Ester HD, manufactured by Shin-Nakamura Chemical Co., Ltd.) (D) Component (D1): 1-hydroxycyclohexyl phenyl ketone (Trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) (D2): methylphenylglyoxylate (trade name: Vicure-55, manufactured by Stouffer)

Comparative Example 1 is an example of a coating composition containing an unsaturated compound other than the component (C) in the present invention. The composition of the present invention is more resistant to sulfuric acid, abrasion and scratches than the composition of the present invention. The cured coating film had poor solvent properties.

Comparative Example 2 is an example of a coating composition containing a polymer compound other than the component (A) in the present invention, and was a cured coating film having poor sulfuric acid resistance and solvent resistance.

Comparative Example 3 is an example of a coating composition containing a polymer compound other than the component (A) in the present invention and an unsaturated compound other than the component (C) in the present invention. The cured coating film had poor sulfuric acid properties, solvent resistance, and abrasion resistance.

Comparative Example 4 is an example of a coating composition having a small amount of the component (A) in the present invention, and was a cured coating film inferior in weather resistance, surface tackiness and adhesion.

Comparative Example 5 is an example of a coating composition containing a large amount of the component (A) in the present invention, and is inferior in coating film appearance, sulfuric acid resistance, solvent resistance, scratch resistance, pencil hardness, and weather resistance. It was a coating film.

Comparative Example 6 is an example of a coating composition containing less component (B) in the present invention, and was inferior in abrasion resistance and surface tackiness.

Comparative Example 7 is an example of a coating composition containing a large amount of the component (B) in the present invention. The coating film appearance, sulfuric acid resistance, solvent resistance, scratch resistance, pencil hardness, weather resistance, adhesion The cured coating film was poor.

Comparative Example 8 is an example of a coating composition containing a large amount of the component (C) in the present invention.
The cured coating film had poor adhesion.

Comparative Example 9 is an example of a coating composition containing no unsaturated compound in the present invention, and shows the appearance of a coating film, sulfuric acid resistance, solvent resistance, scratch resistance, pencil hardness, weather resistance, and adhesion. The cured coating film was poor.

[0111]

The present invention is an epoch-making composition which is tack-free after application to a substrate and does not cause sagging. In addition, a high-hardness cured coating film with excellent transparency, scratch resistance, solvent resistance, sulfuric acid resistance, and weather resistance can be formed on the substrate surface, and is hardened by irradiation with active energy rays, so workability is improved. And to solve the problem of preventing global warming. As described above, the present invention can easily achieve excellent surface improvement of various base materials in a short time, and is extremely useful in industry.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C09D 143/04 C09D 143/04 F-term (Reference) 4F100 AA20C AK25C AT00A BA03 BA07 BA10A BA10C CC00B CC00C DE01C GB32 JB01 JB12B JB12C JB14C JJ03 JK14 JL09 JL10B JN01 JN01C 4J038 DL122 FA132 FA172 FA212 FA221 FA231 HA446 KA03 KA06 NA01 NA03 NA11 NA12 NA14 PA17 PB03 PB07 PC02 PC03 PC06 PC08 PC10

Claims (10)

[Claims] (A) 20 to 80% by mass of a polymer compound having an acryloyloxy group in a side chain; (B) 40 to 90% by mass of (b1) colloidal silica fine particles (solid content); Formula (I) (Wherein, X represents a methacryloyloxy group, an acryloyloxy group, or a vinyloxy group, and R ¹ has 0 to 8 carbon atoms.
R ² and R ^{3 each} represent a linear or branched alkyl group having 1 to 8 carbon atoms, n represents a positive integer of 0 to 2, and m + n represents a positive integer of 1 to 3 Is a number. ) Or a hydrolyzate thereof (solid content)
60% by mass (however, the total amount of the component (b1) and the component (b2) is 1
A) an alicyclic compound having at least one acryloyloxy group in one molecule (C) 2 to 60% by mass of curable silicon (solid content) obtained by hydrolysis and condensation reaction Group and / or heterocyclic compound group 5 having one or more acryloyloxy groups in one molecule
A curable composition for coating comprising (D) 0.01 to 10 parts by mass of a radical polymerization initiator with respect to 100 parts by mass in total of 50 to 50% by mass. 2. A coating curable composition comprising 100 parts by mass of the total of components (A) to (C) and 10 to 1000 parts by mass of an organic solvent (E). 3. The curable composition for coating according to claim 1, wherein the radical polymerization initiator (D) is a compound that generates a radical by an active energy ray. 4. A base material having a colored base coat film and one or more clear top coat films sequentially formed thereon, and the outermost clear top coat film is provided.
A multilayer cured coating film comprising the curable composition for coating as described above as a main component. 5. The multi-layer cured coating film according to claim 4, wherein the clear top coat film has been polymerized and cured by irradiation with active energy rays. 6. A clear top coat film having a thickness of 5 to 80 μm.
The multilayer cured coating film according to claim 4, wherein the coating film is transparent in the range of m. 7. The multilayer cured coating film according to claim 4, wherein the colored base coat film is a cured product of a coating composition containing water. 8. A coated article having a cured coating film of the curable composition for coating according to claim 1. 9. An automotive outer panel having the multilayer cured coating film according to any one of claims 4 to 7. 10. An active energy ray-curable composition, wherein a coating film comprising the composition according to claim 1 becomes tack-free before polymerization and curing.