JP2001316603A - Curable composition for coating, multilayer cured coating film, coated article, automotive outer panel and active energy ray curable composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a curable composition for coating that can form a cured coating film excellent in transparency, mar resistance, heat resistance, chemical resistance, weathering resistance and adhesion to a primer coat and produce an active energy ray curable composition that gives a coating film which will become tack free before it is cured when formed on a substrate. SOLUTION: This curable composition for coating is produced by blending (D) 0.01-10 pts.wt. radical polymerization initiator in 100 pts.wt. of the total of (A) 20-80% polymer compound having one or more C=C bonds, i.e., carbon-to- carbon unsaturated double bonds, in its side chain, (B) 2-60% curable silicone obtained by subjecting 40-90% colloidal silica fine particles b1 and 10-60% monomer or its hydrolyzate b2 of formula I [wherein, X is a (meth)acryloyloxy group or vinyloxy group; R1 to R3 are each independently 8C or less alkyl group; and m+n is a positive number of 1 to 3 (provided that the total of b1 and b2 is 100%)] to hydrolysis and condensation reaction and (C) 5-50% ethylenically unsaturated compound having two or more (meth)acryloyloxy groups in one molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] The present invention relates to a novel composition, and more particularly, to a substrate having excellent transparency, abrasion resistance, heat resistance, chemical resistance, weather resistance, and a base coat. Curable composition capable of forming an overcoat film having excellent adhesion to the coating, a multilayer cured film having a clear top coat film containing the composition as a main component, and 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 In the past, paints for top coating such as automobile outer panels have 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 abrasion 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 at the same time There is a need for a topcoat that can form a satisfactory coating.

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-mentioned measures against acid rain and scratch resistance are obtained by using a polymer having a carboxyl group and a hydroxyl group in a molecule and a polymer having an epoxy group and a hydroxyl group in a molecule as a top coat by heat curing. Methods have been proposed to simultaneously satisfy the overcoming. Furthermore, 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.

However, in these methods, although the performance of the coating film itself can be improved, since the coating is a heat-curable coating, a large amount of electricity is required at the time of heating, and the latter problem, that is, carbon dioxide is required. Emissions cannot be reduced and cannot contribute to the prevention of global warming.

[0006] Among the performances required for an automobile outer panel, abrasion resistance has been limited as the industry standard becomes higher in a coating film composed of only an organic material. for that reason,
As a method for improving the scratch resistance of a transparent synthetic resin molded article in which scratch resistance is regarded as important, for example, a paint comprising a partially hydrolyzed condensate of a silane mixture containing an alkyl trialkoxysilane as a main component and colloidal silica is used. A method has been found in which a coating is applied to the surface and then heat-treated to form a crosslinked coating film to improve the scratch resistance (US Pat. No. 4,060,271).

According to this method, a coating film having a high degree of scratch resistance can be obtained. However, since this is a heat-curable coating material, the curing time is long and heat energy is required for curing. It has no effect on reducing carbon emissions. Further, it is difficult to form the above-mentioned coating film on the colored base coat film.

As a technique effective in 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. Disclosed is a method of applying a UV-curable coating composed of an alkoxysilane having a glycidyl functional group and a non-silyl acrylate to the surface of a molded product, and then irradiating the UV-curable coating with ultraviolet light to obtain a synthetic resin molded product having excellent scratch resistance. Have been. According to this method, the curing time of the conventional silicon-based coating film is greatly reduced by using an ultraviolet-curable coating material, and the scratch resistance of the coating film can be improved.

However, although this method can be applied to a substrate having a simple shape, it cannot be applied to a substrate having a three-dimensional shape such as an automobile outer panel.

That is, in order to coat a substrate having a three-dimensional shape, no dripping of the paint occurs after application to the substrate.
In addition, it is necessary to form a tack-free coating film before polymerization and curing. However, the above-mentioned ultraviolet-curable paint, after application, even after volatilizing the organic solvent contained in the coating film, causes dripping in a liquid state. The film has impurities such as dust and dirt adhering to the coating film.
At present, the UV-curable paints cannot be used for automobile outer panels.

[0011]

The inventors of the present invention have conducted 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 the above, when containing an organic solvent, a polymer compound having a radical polymerizable functional group in a molecule, in which a tack-free coating film is obtained after volatilization thereof,
Also, attention was paid to using an ethylenically unsaturated compound capable of imparting toughness to a coating film.

That is, the present invention provides: (A) 20 to 80% by mass of a polymer compound having a side chain having at least one carbon-carbon unsaturated double bond;
(B) (b1) Colloidal silica fine particles (solid content) 40 to 9
0% by mass and (b2) the following general formula (I)

Embedded image

Wherein X is a methacryloyloxy group, an acryloyloxy group or a vinyloxy group, R ¹ is 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 is a positive number of 1 to 3. ) Of 10 to 60% by mass (provided that the total amount of component (b1) and component (b2) is 100 parts by mass), (C) 5 to 50% by mass of ethylenically unsaturated compound having at least two or more (meth) acryloyloxy groups in one molecule For 100 parts by mass,
(D) a curable composition for coating comprising 0.01 to 10 parts by mass of a radical polymerization initiator, and the curable composition for coating further coated on a colored base coat film previously formed on a substrate. A multilayer cured coating film having a clear top coat film as a main component formed thereon, a coated article having a cured coating film of the curable composition for coating, and a coating film formed on a substrate before polymerization curing is tack-free. Active energy ray-curable composition.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the curable composition for coating of the present invention will be described in detail. The curable composition for coating (hereinafter, abbreviated as “coating composition”) of the present invention includes: (A) a polymer compound having a side chain having at least one or more carbon-carbon unsaturated double bond; mass%,
(B) (b1) Colloidal silica fine particles (solid content) 40 to 9
0% by mass and (b2) the following general formula (I)

[0015]

Embedded image (In the formula, 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 are linear or branched alkyl groups having 1 to 8 carbon atoms, n is a positive integer of 0 to 2, and m + n is 1 to 3 Is a number. ) Or a hydrolyzate thereof (solid content)
60% by mass (provided that the total amount of the component (b1) and the component (b2) is 1
(To be 00 parts by mass), 2 to 60% by mass of curable silicon (solid content) obtained by hydrolysis and condensation reaction, and (C) at least two or more (meth) acryloyloxy groups in one molecule. Ethylenically unsaturated compounds 5-5
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 0% by mass.

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

The component (A) of the present invention is a polymer compound having a side chain having at least one carbon-carbon unsaturated double bond, and is a component for imparting flexibility.

Specific examples of the component (A) include, for example, an acid anhydride group of a copolymer composed of a vinyl monomer having an acid anhydride group such as maleic anhydride and itaconic anhydride and another copolymerizable monomer. Obtained by adding a vinyl monomer having a hydroxyl group such as hydroxyalkyl (meth) acrylate to a polymer; a copolymer comprising a vinyl monomer having a carboxyl group such as acrylic acid and methacrylic acid and another copolymerizable monomer Compounds obtained by adding a vinyl monomer having an epoxy group such as glycidyl (meth) acrylate to the carboxyl group of the above.

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 or a vinyl monomer having a carboxyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and 2- (meth) acrylate. Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (Meth) acrylates such as (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, and (meth)
(Meth) acrylamides such as acrylamide and N-butoxy (meth) acrylamide; vinyl compounds such as styrene, α-methylstyrene, vinyltoluene and vinyl acetate; allyls such as glycerin monoallyl ether, allyl alcohol and ethylene glycol monoallyl ether Ether alcohol compounds and the like can be mentioned.

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 component (B) and the component (C) described later, 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
When it is smaller than about 000, the coating film performance after curing tends to decrease, and when it is larger than about 50,000, the compatibility of the composition tends to decrease.

The amount of the polymer compound (A) (solid content) used in the coating composition of the present invention is in the range of 20 to 80% by mass, preferably 30 to 7% by mass, per 100 parts by mass of the coating composition.
It is in the range of 5% by mass, more preferably in the range of 40 to 70% by mass.

The amount of the polymer compound (A) used is 20% by mass.
When the amount is less, poor performance occurs such as sagging easily at the time of film formation, poor tackiness on the surface of the cured film, and extremely reduced flexibility of the cured film, making the film easily crackable. When the content exceeds 80% by mass, the appearance, chemical resistance, surface hardness, abrasion resistance, and weather resistance of the cured coating film 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)

[0027]

Embedded image

Wherein X is a methacryloyloxy group, an acryloyloxy group or a vinyloxy group, R ¹ is 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 is a positive number of 1 to 3. ) Of 10 to 60% by mass (provided that the total amount of component (b1) and component (b2) is 100 parts by mass), Curable silicone (solid content) obtained by

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 size 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;
Polyhydric alcohol derivatives such as ethylene cellosolve and butyl cellosolve; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and diacetone alcohol; 2-
Examples include monomers such as 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 diameter 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 silane compound) represented by the above general formula (I) or its hydrolyzate, which is the component (b2), reacts with the colloidal silica fine particles (b1) to produce a polymer compound ( A component for improving the compatibility between A) and the ethylenically unsaturated compound (C).

As the component (b2), a silane compound having an acryloyloxy group, a methacryloyloxy group, or a vinyl group having polymerization activity upon irradiation with ultraviolet rays is used. By using this silane compound, the polymer compound (A) And the ethylenically unsaturated compound (C) can form a chemical bond, whereby the cured coating film can be provided with adhesion to the surface of the synthetic resin molded product.

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

Specific examples of the component (b2) include, 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, vinyltriethoxy At least one silane compound selected from silanes or a hydrolyzate thereof is particularly preferred.

The hydrolysis is carried out by adding 0.5 to 6 mol of water or 0.001 mol of silane compound to 1 mol of silane compound in the presence or absence of an organic solvent such as an alcohol solvent.
A first step of adding a hydrolysis catalyst such as an aqueous solution of 0.1 N hydrochloric acid or acetic acid and stirring the mixture under heating to remove the alcohol produced by the hydrolysis outside 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 as follows, in the presence of the colloidal silica fine particles (b1) and the hydrolyzate of the silane compound (b2).
The dispersion medium in the colloidal silica fine particles (b1) is azeotropically distilled with a non-polar 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 in a step of reacting 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)
After the azeotropic distillation of the dispersion medium with the non-polar solvent under normal pressure or reduced pressure, and replacing the dispersion medium with a non-polar solvent, 60 ~
In the temperature range of 150 ° C, preferably 80 to 130 ° C, the solid content concentration is in the range of 30 to 90% by mass, preferably 50 to 90% by mass.
Stir for 0.5 to 10 hours while maintaining 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) thus obtained was hydrophobized by coating the surface of the hydrophilic colloidal silica fine particles (b1) with (meth) acryloyl-functional silicon, so that it is used in the present invention. Polymer compound (A)
And the ethylenically unsaturated compound (C) have improved compatibility,
The transparency of the obtained cured coating film becomes good. In particular, when the cured coating film of the composition of the present invention is formed into a thick film, the haze value of the coating film becomes very small, and the appearance as a clear top coat film tends to be excellent.

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

During the production of the component (B), it is preferable to keep the solid content concentration 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 solvent exceeds 70% by mass, the reaction between the component (b1) and the component (b2) tends to be insufficient. Tends to have poor transparency. On the other hand, if the solid content concentration exceeds 90% by mass, a rapid reaction occurs and 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).

The proportion of the component (b1) and the component (b2) is such that, for example, when the component (b1) exceeds 90% by mass, the reaction system tends to be clouded or gelled. Cracks tend to occur easily.

On the other hand, when the component (b1) is more than 40% by mass, (b)
The reaction between the component (1) and the component (b2) is sufficient, and when a thick cured coating film is formed, the scratch resistance and transparency of the coating film are improved.

In the present invention, the component (b1) and the component (b)
2) By reacting with the component, an unprecedented excellent curability is developed, and a cured coating film which is transparent and excellent in scratch resistance can be formed even in an air atmosphere.

The amount of the curable silicone (B) used in the coating composition of the present invention is determined based on 100 parts by mass of the coating composition.
The range is 2 to 60% by mass, preferably 10 to 50% by mass, and more preferably 15 to 40% by mass.

The amount of the curable silicon (B) used is 2% by mass.
If the amount is less than the above, the effect of improving the scratch resistance tends to be insufficient, while if it exceeds 60% by mass, the surface tackiness, appearance of the cured coating film, chemical resistance, abrasion resistance, surface hardness, weather resistance There is a tendency that various performances such as generation of cracks due to poor properties become poor.

The ethylenically unsaturated compound having at least two (meth) acryloyloxy groups in one molecule, which is the component (C) of the present invention, is not particularly limited. Aromatic or aromatic ester mono- or poly (meth) acrylates, aliphatic, alicyclic or aromatic urethane poly (meth) acrylates, epoxy poly (meth) acrylates, polyester poly (meth) Acrylate and the like can be used.

Specific examples of the component (C) include, for example,
1,4-butanediol di (meth) acrylate, 1,
6-hexanediol di (meth) acrylate, 1,9
-Nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol (n = 2 to 15) di (meth) acrylate, polypropylene glycol (n = 2 to 15) Di (meth) acrylate, polybutylene glycol (n = 2 to 15) di (meth) acrylate, 2,2-bis (4- (meth) acryloyloxyethoxyphenyl) propane, 2,2-bis (4- (meth) ) Di (meth) acrylate compounds such as acryloyloxydiethoxyphenyl) propane, trimethylolpropane diacrylate, bis (2- (meth) acryloyloxyethyl) hydroxyethyl-isocyanurate; trimethylolpropane tri (meth)
Acrylate, tris (2- (meth) acryloyloxyethyl) isocyanurate, tris (2- (meth) acryloyloxypropyl) isocyanurate, bis (2- (meth) acryloyloxyethyl) hydroxyethyl isocyanurate, bis (2- (Meth) acryloyloxypropyl) -2-ethoxypropyl isocyanurate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, di Polyfunctional (meth) acrylate compounds such as pentaerythritol hexa (meth) acrylate; epoxy di (meth) obtained by reacting bisphenol A type epoxy with (meth) acrylic acid Epoxy poly (meth) acrylate such as acrylate; urethane tri (meth) acrylate obtained by reacting 2-hydroxyethyl (meth) acrylate with a trimer of 1,6-hexamethylene diisocyanate, isophorone diisocyanate and 2-hydroxypropyl (meth) Urethane di (meth) acrylate reacted with acrylate, urethane hexa (meth) acrylate reacted with isophorone diisocyanate and pentaerythritol tri (meth) acrylate, dicyclomethane diisocyanate and 2-hydroxyethyl (meth) acrylate The reacted urethane di (meth) acrylate, urethanation product of dicyclomethane diisocyanate and poly (n = 6 to 15) tetramethylene glycol are treated with 2-hydroxyethyl (meth) Urethane poly (meth) acrylates such as urethane di (meth) acrylate reacted with acrylate; polyester (meth) acrylate reacted with trimethylolethane and succinic acid, (meth) acrylic acid, trimethylolpropane and succinic acid, Ethylene glycol, and (meth)
Examples thereof include polyester poly (meth) acrylates such as polyester (meth) acrylate reacted with acrylic acid. These compounds may be used alone or in combination of two or more.

Among these, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, tris (2- (meth) acryloyloxy) Ethyl) isocyanurate, bis (2- (meth) acryloyloxyethyl) hydroxyethyl isocyanurate, trimethylolpropanetri (meth) acrylate, 1,6-hexamethylene diisocyanate trimer and 2-hydroxyethyl (meth) acrylate Urethane tri (meth) acrylate, isophorone diisocyanate and pentaerythritol tri (meth) acrylate Dicyclopentyldimethoxysilane diisocyanate and 2-hydroxyethyl (meth) urethane di obtained by reacting acrylate (meth) acrylate, trimethylolpropane tri (meth) acrylate, tris (2-
It is particularly preferable to use one type of compound selected from (meth) acryloyloxyethyl) isocyanurate and 1,6-hexanediol di (meth) acrylate alone or in combination of two or more types.

The amount of the ethylenically unsaturated compound (C) used in the coating composition of the present invention is in the range of 5 to 50% by mass, preferably 10 to 30% by mass, per 100 parts by mass of the composition. .

If the amount of the ethylenically unsaturated compound (C) used is less than 5% by mass, the weather resistance of the cured coating film obtained and the adhesion to the substrate tend to decrease, while the amount exceeds 50% by mass. Cracks tend to occur in the cured coating film and 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) only needs to generate radicals, and may be a compound that generates radicals by active energy rays or a compound that generates radicals by heat.

Specific examples of the compound which generates a radical by the active energy ray of the component (D) include, for example, 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, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4-bis (dimethylamino Benzophenone), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1
Carbonyl compounds such as -one; sulfur compounds such as tetramethylthiuram disulfide; azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile; peroxide compounds such as benzoyl peroxide and ditert-butyl peroxide. 2,4,6-
Trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,
Examples include acylphosphine oxide compounds such as 4-trimethylpentylphosphine oxide.

Specific examples of the compound which 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, in the present invention, one or more compounds selected from benzophenone, 1-hydroxycyclohexylphenyl ketone, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide methylphenylglyoxylate are particularly preferred. In addition,
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.

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

When 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.

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; Solvents based on polyhydric alcohol derivatives such as methoxybutanol and ethyldiglycol are exemplified.

These organic solvents (E) may be used in various physical properties 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 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) in order to improve coating workability. As a particularly preferred specific example in this case, when the organic solvent (E) is 100% by mass, the alcohol-based organic solvent (e1) is 0 to 30% by mass,
Acetate organic solvent (e2) 0 to 30% by mass, ketone solvent (e3) 1 to 30% by mass, polyhydric alcohol derivative solvent (e4) 1 to 30% by mass, aromatic solvent (e5) 1 to 1 3
A combination of 0% by mass is exemplified.

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 100 parts by weight of the total of components (A) to (C). ８００800 parts by mass. When the use amount of the organic solvent (E) exceeds 1000 parts by mass, it may take a long time for the solvent to evaporate, or the workability may be deteriorated such that the coating tends to sag.

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 thickening agent, an anti-settling agent, Various additives such as an antistatic agent, an antifogging agent, an ultraviolet absorber, and a light stabilizer may be included.

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

In order to form the multilayer cured coating film of the present invention, the coating composition is first coated by a known method such as a brush coating method, a spray coating method, a shower flow coating method, a dip coating method, and a curtain coating method. What is necessary is just to apply to a base material.

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

Means for curing the coating film of the coating composition may be 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 high in 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 them 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 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 carried out at room temperature as it is, or at a temperature of 20 to 120 ° C. and 1 to 60 using an infrared or hot air drying oven.
The heat treatment may be performed for a minute.

The substrate on which the multilayer cured coating film of the present invention is formed is not particularly limited. The substrate is obtained by electrodepositing a primer on a chemically treated steel sheet and, if necessary, applying an intermediate coating. And various plastic base materials (which may be subjected to a surface treatment such as primer coating or intermediate coating if necessary), or a composite member obtained by combining these materials.

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 of the composition. The article here is not particularly limited, such as glass, metal, wood, paper, cloth, etc., in addition to the above-mentioned base material. Articles having a cured coating film of the coating composition of the present invention are particularly suitable for automobile outer panels.

As a specific method for producing an automobile outer panel, for example, a colored base coat film is formed on a substrate with a thermosetting colored paint, and then a clear top coat film is formed on the colored base coat film with the composition of the present invention. Is formed.

Specific examples of the thermosetting coloring paints mentioned here include, for example, acrylic resin / amino resin, alkyd resin / amino resin, polyester resin / amino resin, acrylic resin / polyisocyanate, alkyd resin / A coating composition in which a coloring pigment is blended with a known resin composition such as a polyisocyanate type, a polyester resin / polyisocyanate type, an epoxy acrylic resin / a carboxylic acid type acrylic resin, and 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-dispersion type, an aqueous solution type, and a water dispersion type. However, from the viewpoint of suppressing the discharge amount of the solvent 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.

The active energy ray-curable composition of the present invention is a composition in which a coating film formed on a substrate becomes tack-free before polymerization and curing.

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 the workability can be improved. In particular, the composition can be put to practical use as a clear coat film for automotive outer panels. This can simultaneously solve the problems of curability by irradiation with active energy rays, good productivity in a short time, and prevention of global warming.

Specific examples of such innovative compositions include, for example, the above-described coating compositions, but are not limited thereto.

[0087]

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 on which a coating film of the curable composition for coating was 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 film has no abnormality and is excellent in smoothness. X: The surface of the cured coating film has a yuzu-skin shape or considerable unevenness, and is inferior 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. ：: The cured coating surface was not etched. X: The cured coating surface was etched.

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 cured coating film surface was visually evaluated. ：: No change Δ: Scratched or cloudy coating X: Swelling or dissolution of coating

[0092] 5. Scratch resistance: The felt impregnated with the cleanser was reciprocated 20 times with a load of 500 g. And
The light reflectance is measured with a gloss meter (Nippon Denshoku Industries Co., Ltd., trade name:
Gloss meter VG2000) was used to calculate the gloss retention of the cured coating film from the initial gloss and the scratch gloss. 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 according to JIS K 5400 (Mitsubishi Pencil Co., Ltd., trade name Uni). It should be noted that a pencil hardness of H or higher is indicated as a pencil hardness pass (○).

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

<Preparation of Polymer Compound> Synthesis Example 1 165 parts by mass of methyl methacrylate, 45 parts by mass of n-butyl methacrylate, 51 parts by mass of styrene, 9 parts of methacrylic acid
A mixed solution (a1) of 30 parts by mass of maleic anhydride, 30 parts by mass of azobisisobutyronitrile and 90 parts by mass of propylene glycol monomethyl ether acetate
Was adjusted.

Next, 300 parts by mass of n-butyl acetate was charged into a two-liter four-necked flask equipped with a stirrer and a condenser, heated to 120 ° C. while purging with nitrogen, and the mixed solution (a1) was added for 4 hours. Then, a solution prepared by dissolving 1.2 parts by mass of azobisisobutyronitrile in 60 parts by mass of propylene glycol monomethyl ether acetate was added dropwise over 2 hours. Further, a mixture of 3 parts by mass of triethylamine and 44.1 parts by mass of 4-hydroxybutyl acrylate was dropwise added at 80 ° C. over 1 hour, stirred, and then heated and stirred at 90 ° C. for 4 hours.

Subsequently, 58.2 parts by mass of glycidyl methacrylate was added dropwise at 70 ° C. over 1 hour, followed by stirring at 90 ° C., and after confirming that the acid value was 5 mgKOH / g or less, the reaction was continued. finished. Thus, a solution containing the polymer compound (A1) at 49% by mass was obtained. The weight average molecular weight of the obtained polymer compound (A1) is 4000 to 50.
00.

Synthesis Example 2 195 parts by mass of methyl methacrylate, 15 parts by mass of n-butyl methacrylate, 45 parts by mass of methacrylic acid, 45 parts by mass of isobornyl methacrylate, 30 parts by mass of azobisisobutyronitrile and propylene glycol monomethyl ether acetate 90 parts by mass of the mixed solution (a2) was prepared.

Next, 300 parts by mass of n-butyl acetate was charged into a two-liter four-necked flask equipped with a stirrer and a condenser, heated to 120 ° C. while purging with nitrogen, and the mixed solution (a2) was added for 4 hours. Then, a solution prepared by dissolving 1.2 parts by mass of azobisisobutyronitrile in 60 parts by mass of propylene glycol monomethyl ether acetate was added dropwise over 2 hours. Further, a mixture of 6 parts by mass of tetrabutylammonium bromide and 75 parts by mass of glycidyl methacrylate was dropped at 80 ° C. over 1 hour and stirred, and then the reaction was terminated after confirming that the acid value was 5 mgKOH / g or less. did.

Thus, a solution containing the polymer compound (A2) at 48% by mass was obtained. The obtained polymer compound (A
The weight average molecular weight of 2) was 4000 to 5000.

Synthesis Example 3 180 parts by mass of methyl methacrylate, 45 parts by mass of n-butyl methacrylate, 15 parts by mass of methacrylic acid, 6 parts of styrene
A mixed solution (a3) of 0 parts by mass, 30 parts by mass of azobisisobutyronitrile and 90 parts by mass of propylene glycol monomethyl ether acetate was prepared.

Next, 300 parts by mass of n-butyl acetate was charged into a two-liter four-necked flask equipped with a stirrer and a condenser, heated to 120 ° C. while purging with nitrogen, and the mixed solution (a3) was added for 4 hours. After stirring and reacting, a solution prepared by dissolving 1.2 parts by mass of azobisisobutyronitrile in 60 parts by mass of propylene glycol monomethyl ether acetate was added dropwise over 2 hours, followed by stirring at 130 ° C. for 3 hours. Was done.

Thus, a solution containing 42% by mass of the polymer compound (A3) was obtained. The obtained polymer compound (A
The weight average molecular weight of 3) was 4000 to 5000.

<Synthesis of Curable Silicon> Synthesis Example 4 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 Co., 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, volatiles were distilled off over 2 hours. The distilled off was 1204 parts by mass.
Thereafter, the temperature of the reaction system was increased, and the temperature was increased to 110
The reaction was performed at 4 ° 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> 102 parts by mass (solid content: 49% by mass) of a solution containing the polymer compound (A1) as the component (A),
(B) 33 parts by mass of curable silicone (B1) (solid content: 60% by mass) as a component, and (C) component isocyanuric acid EO modified triacrylate (trade name: M-315, manufactured by Toa Gosei Co.) (C1) 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 Stofer)
One part by mass was stirred and mixed to prepare a coating composition.

<Preparation of Evaluation Test Plate> A zinc phosphate-treated steel plate (10 cm × 30 cm) is coated with a cationic electrodeposition paint for automobiles, baked at 180 ° C. for 30 minutes, and further coated with an aminoalkyd intermediate coating. After baking at 160 ° C. for 30 minutes, the coating film was ground with water to obtain a dried plate. The coating composition shown in Table 1 was applied to this plate, and the composition was applied to a plate under an air atmosphere using a high-pressure mercury lamp (manufactured by Fusion).
Ultraviolet light of 00 mJ / cm ² (integrated energy of ultraviolet light having a wavelength of 320 to 380 nm) was irradiated to obtain an evaluation test plate having a cured coating film having a thickness of 35 μm. Table 1 shows the evaluation results of the obtained cured coating films.

Examples 2 to 5 and Comparative Examples 1 to 10 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 this cured coating film are also shown in Table 1.

[0109]

[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 amount of the organic solvent contained in the solution described in Synthesis Examples 1 to 4 and the amount of the organic solvent added alone.

Furthermore, 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) (A3): Polymer polymerized in Synthesis Example 3 Compound (solid content) (B) component (B1): photocurable organosilicon synthesized in Synthesis Example 4 (solid content) (C) component (C1): isocyanurate EO modified triacrylate (trade name: M-315) (C2): 4-hydroxybutyl acrylate (C3): tetrahydrofurfuryl acrylate

(D) Component (D1): 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) (D2): Methyl phenyl glyoxylate (trade name: Vicure-55, Stoffer) Company)

Comparative Example 1 is an example of a coating composition containing no component (B) in the present invention.
The cured coating film had poor solvent resistance.

Comparative Example 2 is a coating composition containing a polymer compound other than the component (A) in the present invention, so that although the surface tackiness and the appearance of the coating film are good, the sulfuric acid resistance, the solvent resistance, and the The cured coating film had poor abrasion resistance.

Comparative Example 3 is an example of a coating composition containing no component (C) in the present invention, and was a cured coating film having poor solvent resistance and scratch resistance.

Comparative Example 4 is an example of the coating composition containing no component (C) in the present invention, and was a cured coating film having poor solvent resistance and scratch resistance.

Comparative Example 5 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 having poor surface tackiness.

Comparative Example 6 is an example of a coating composition containing a large amount of the component (A) in the present invention, and was a cured coating film having poor coating film appearance, sulfuric acid resistance and solvent resistance.

Comparative Example 7 is an example of a coating composition having a small amount of the component (B) in the present invention, and was a cured coating film having poor scratch resistance.

Comparative Example 8 is an example of a coating composition containing a large amount of the component (B) in the present invention, and was a cured coating film inferior in all evaluation results.

Comparative Example 9 is an example of a coating composition containing a large amount of the component (C) in the present invention, and was a cured coating film having poor surface tackiness and film appearance.

Comparative Example 10 is an example of a coating composition containing no component (C) in the present invention, and is a cured coating film having poor coating film appearance, sulfuric acid resistance, solvent resistance, scratch resistance, and pencil hardness. Met.

[0123]

The composition of the present invention is an active energy ray-curable composition which is tack-free before polymerization and cure and has no sagging, which has never been seen before. Also,
To form a cured coating with excellent transparency, scratch resistance, heat resistance, chemical resistance, weather resistance, and adhesion to the underlying coating on the substrate surface, and to cure by irradiation with active energy rays, This solves the problem of preventing global warming.
Further, since excellent surface improvement of various substrates can be easily achieved in a short time, it is extremely useful industrially.

Claims (10)

[Claims] (A) a polymer compound having a side chain having at least one or more carbon-carbon unsaturated double bond;
80% by mass, (B) (b1) 40 to 90% by mass of colloidal silica fine particles (solid content), and (b2) the following general formula (I): (In the formula, 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 are linear or branched alkyl groups having 1 to 8 carbon atoms, n is a positive integer of 0 to 2, and m + n is 1 to 3 Is a number. ) Or a hydrolyzate thereof (solid content)
60% by mass (provided that the total amount of the component (b1) and the component (b2) is 1
(To be 00 parts by mass), 2 to 60% by mass of curable silicon (solid content) obtained by hydrolysis and condensation reaction, and (C) at least two or more (meth) acryloyloxy groups in one molecule. Ethylenically unsaturated compounds 5-5
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 0% by mass. 2. The curable composition for coating according to claim 1, wherein 10 to 1000 parts by mass of the organic solvent (E) is blended with 100 parts by mass of the total amount of the components (A) to (C). 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 method according to claim 1, wherein a clear top coat film comprising the curable composition for coating according to claim 1 as a main component is formed on a colored base coat film previously formed on the base material. Characterized multilayer cured coating. 5. The multilayer cured coating film according to claim 4, wherein the clear top coat film is 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 cured multilayer 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 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 formed on a substrate becomes tack-free before polymerization and curing.