JP2923125B2 - Paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition which can form a coating film having excellent acid resistance, weather resistance and abrasion resistance and which is suitable as a top coating for automotive coating.

[0002]

2. Description of the Related Art One of the important properties of an overcoat for automotive coating is to form a coating film having excellent finished appearance such as smoothness, gloss and sharpness. Finish appearance, with the top coat paint for automotive coating mainly composed of the hydroxyl group-containing acrylic resin and amino resin currently used,
A coating film excellent in weather resistance, physical function, and the like can be obtained. However, in recent years, air pollution has progressed, and the damage caused by acid rain such as forest withering has become a serious social problem. Particularly, automobile outer panels coated with the above-mentioned coating film have a disadvantage that the surface is easily deteriorated. ing. Also, coatings applied to articles used outdoors have problems that they are etched by acid rain, and whitening and spots occur on the coatings. Have been. Furthermore, coatings applied to automobile outer panels and the like are easily scratched by friction with a cleaning brush or the like, which is one of the causes of deterioration in appearance. strong.

[0003]

Means for Solving the Problems The present inventors have developed a topcoat paint which forms a coating film having significantly improved acid resistance without impairing the finished appearance, weather resistance and physical properties of the coating film. For the purpose, as a result of intensive studies, a hydroxyl group-containing acrylic copolymer containing 45 to 55% by weight of a styrene monomer and obtained by a copolymerization reaction between the styrene and a specific acrylate monomer, and an amino acid The present inventors have found that a coating composition containing a resin or a (block) polyisocyanate compound as a cured resin component provides a coating film having excellent acid resistance and weather resistance, and have completed the present invention.

That is, the present invention relates to the following components (A) styrene monomer, hydroxyl group-containing monoacrylate monomer and acrylate monomer of monohydric alcohol having 4 to 24 carbon atoms (hereinafter referred to as "long-chain acrylate monomer"). Is an acrylic copolymer having a hydroxyl value of 60 to 140 mg KOH / g resin, a weight average molecular weight of 3,000 to 30,000, and a styrene monomer content of The present invention relates to a coating composition containing a curable resin composition containing 90 to 50% by weight of an acrylic copolymer, which is 45 to 55% by weight, and (B) 10 to 50% by weight of an amino resin and / or a (block) polyisocyanate compound. .

The acrylic copolymer used in the coating composition of the present invention has a hydroxyl value of 60 to 140 mgKOH / g resin, preferably 90 to 120 mgKOH / g resin, and a weight average molecular weight of 3,000 to 30,000. Preferably 5,000 to 2
It is in the range of 0000. When the hydroxyl value is less than 60 mg KOH / g resin, the coating performance such as acid resistance and scratch resistance is poor, and when it exceeds 140 mg KOH / g resin, the compatibility with a crosslinking agent such as amino resin and (block) polyisocyanate is impaired. As a result, the appearance of the finished paint deteriorates. When the weight average molecular weight is less than 3,000, the coating properties such as acid resistance and weather resistance are poor, and when the weight average molecular weight exceeds 30,000, the finished appearance of the coating deteriorates.

The acrylic copolymer is obtained by copolymerizing a styrene monomer, a hydroxyl-containing monoacrylate monomer and a long-chain acrylate monomer.

The hydroxyl group-containing monoacrylate monomer used in the acrylic copolymer is a monomer containing one acryloyl group and one or more hydroxyl groups in one molecule, and is a monohydric ester of a dihydric alcohol, ε. -Caprolactone-modified acrylic monomers and the like.

Examples of the acrylate of a dihydric alcohol include 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2,3-dihydroxypropyl acrylate, 1,4-butanediol monoacrylate, and (poly) ethylene glycol. Monoacrylate and the like. Among these, 1,4-butanediol monoacrylate is preferred.

[0009] As the ε- caprolactone-modified acrylic monomer, the following formula _{CH 2 = CH-COOCH 2 CH} 2 O (COC 5 H 10 O) n H

Wherein n is from 0.5 to 5. ], For example, "Placcel FA
-1 "," Placcel FA-2 "," Placcel FA-
3 "," Placcel FA-4 "," Placcel FA-
5 "(all manufactured by Daicel Chemical Industries, Ltd., trade name, ε-caprolactone-modified 2-hydroxyethyl acrylates)
However, the present invention is not limited to this.

In the present invention, a coating film having excellent abrasion resistance is obtained by using an ε-caprolactone-modified acrylic monomer and / or a 1,4-butanediol monoacrylate monomer as an essential component as the hydroxyl group-containing monoacrylate monomer. Is preferred because they can be formed. When these monomers are used, it is preferable that the monomers be contained at 10% by weight or more in all the monomer components.

The long-chain acrylic monomer used in the acrylic copolymer is an acrylate monomer of a monohydric alcohol having 4 to 24 carbon atoms. When the carbon number of the long-chain acrylic monomer is less than 4, the coating properties such as processability, acid resistance, and scratch resistance decrease, and when it exceeds 24, the coating properties such as stain resistance and scratch resistance decrease. Not preferred.
As the long-chain acrylic monomer, specifically, for example, n
-Butyl acrylate, isobutyl acrylate, te
Examples thereof include rt-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, lauryl acrylate, tridecyl acrylate, and stearyl acrylate.

The ratio of each monomer component constituting the acrylic copolymer is as follows: styrene monomer is 45 to 55% by weight;
Hydroxyl-containing monoacrylate monomer is used in an amount such that the copolymer has a hydroxyl value of 60 to 140 mg KOH / g resin, usually about 1
A range of 2 to 40% by weight and the remaining proportion of long chain acrylic monomer, usually about 5 to 43% by weight, is desirable. If the styrene monomer ratio is less than 45% by weight, the coating properties such as acid resistance and surface hardness are poor, and if it exceeds 55% by weight, the coating properties such as weather resistance are poor. Further, when the proportion of the long-chain acrylic monomer is less than about 5% by weight, the coating properties such as processability deteriorate, and when it exceeds about 43% by weight, the coating properties such as acid resistance and surface hardness decrease, which is not preferable. .

In addition to the above-mentioned monomers, conventionally known radically polymerizable monomers can be appropriately selected and used. Specific examples include acrylic acid, maleic acid, maleic anhydride, and acrylonitrile. The monomers can be present in a range of up to about 5% by weight of the total monomer components.

The copolymerization reaction of a styrene monomer, a hydroxyl group-containing monoacrylate monomer, and a long-chain acrylic monomer can be carried out in the same manner as in a conventional method for synthesizing an acrylic resin or a vinyl resin. For example, it can be carried out by dissolving or dispersing the above components in an organic solvent, and heating while stirring at a temperature of about 60 to 180 ° C. in the presence of a radical polymerization initiator. The reaction time is usually 1 to
It may be about 10 hours.

The organic solvent is heptane,
Hydrocarbon solvents such as toluene, xylene, octane, and mineral spirits; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, methyl cellosolve acetate, and butyl carbitol acetate; methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone Ketone solvents, alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol and isobutanol, ether solvents such as n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc. Can be used. Among these, when a hydrocarbon solvent is used, it is preferable to use another solvent in combination from the viewpoint of solubility. As the radical initiator, any of the commonly used radical initiators can be used. Examples thereof include peroxides such as benzoyl peroxide and tert-butylperoxy-2-ethylhexanoate, and azobisisobutyronitrile. And azo compounds such as azobisdimethyl valeronitrile.

An amino resin used in the coating composition of the present invention;
The (block) polyisocyanate compound is for crosslinking the hydroxyl group-containing acrylic copolymer.

As the amino resin to be used, a melamine resin widely used in conventional thermosetting acrylic resin paints can be used. For example, melamine, urea, benzoguanamine, acetoguanamine, spiroguanamine,
A known partially or completely methylolated amino resin obtained by reacting an amino component such as dicyandiamide with an aldehyde can be used. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. In addition, those obtained by etherifying the methylolated amino resin with an appropriate alcohol can also be used. Examples of the alcohol used for the etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, and isobutyl alcohol. Alcohol, 2
-Ethylbutanol, 2-ethylhexanol and the like. In the present invention, it is particularly preferable to use hexamethoxymethylmelamine or some or all substituted by C ₄ or higher alcohol ether melamine resins of the methoxy group. In this case, it is preferable to add a usual curing catalyst such as paratoluenesulfonic acid and dodecylbenzenesulfonic acid.

When a strong acid catalyst as described above is used, triethylamine, diethanolamine, 2-amino-
It may be neutralized (blocked) with an amine compound such as 2-methylpropanol.

Commercially available melamine resins include, for example, butylated melamine resins (Mitsubishi Toatsu Uban 20SE).
-60, Uban 225, Dainippon Ink Super Beckamine G840, Super Beckamine G821, etc.), Methylated melamine resin (Mitsui Cyanamid Co., Ltd. Cymel 303, Sumitomo Chemical Sumimal M-100, Sumimal M-40S etc.) , Methyl etherified melamine resin (Cymel 303 and Cymel 32 manufactured by Mitsui Cyanamid Co., Ltd.)
5, Cymel 327, Cymel 350, Cymel 37
0, Nikarac MS17, Nikarac M, manufactured by Sanwa Chemical
S15, Resin 741 manufactured by Monsanto Co., Ltd., Sumimal M55 manufactured by Sumitomo Chemical Co., Ltd., methylated, butylated mixed etherified melamine resin (Cymel 235, Cymel 202, Cymel 238, Cymel 254, Cymel 272 manufactured by Mitsui Cyanamid Co., Ltd.) And melamine resins such as methylated and isobutylated mixed etherified melamine resins (Cymel XV805 manufactured by Mitsui Cyanamid Co., Ltd., Niclac MS95 manufactured by Sanwa Chemical Co., Ltd.).

The polyisocyanate compound used as a crosslinking agent may be a free isocyanate compound or a blocked isocyanate compound. Examples of the polyisocyanate compound having a free isocyanate group include: aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; cycloaliphatic diisocyanates such as xylene diisocyanate or isophorone diisocyanate; tolylene diisocyanate; Organic diisocyanates themselves such as aromatic diisocyanates such as diphenylmethane diisocyanate, or an adduct of an excess of each of these organic diisocyanates with a polyhydric alcohol, a low molecular weight polyester resin or water, or each of the organic diisocyanates listed above And the isocyanate / biuret form. Examples of typical commercial products are "Varnock D" 750, -800, DN-9
50, -970 or 15-455 "(products of Dainippon Ink and Chemicals, Inc.)," Dismodule L,
N, HL or N3390 "(manufactured by Bayer AG, West Germany)," Takenate D-102, -202, -11
0 or -123N "(product of Takeda Pharmaceutical Co., Ltd.),
"Coronate EH, L, HL or 203" (product of Nippon Polyurethane Industry Co., Ltd.) or "Duranate 24A"
-90CX "(a product of Asahi Kasei Corporation). As the polyisocyanate compound having a blocked isocyanate group, the polyisocyanate compound having a free isocyanate group is an oxime,
Examples thereof include those blocked with a known blocking agent such as phenol, alcohol, lactam, malonic ester, and mercaptan. Examples of these typical commercially available products include “Barnock D-550” (product of Dainippon Ink and Chemicals, Inc.), “Takenate B-815-N” (product of Takeda Pharmaceutical Co., Ltd.), and “Aditol VXL”. -80 "
(A product of Hoechst AG in West Germany) or "Coronate 250
7 "(product of Nippon Polyurethane Industry Co., Ltd.).

The coating composition of the present invention can be obtained by blending the acrylic copolymer with an amino resin and / or a (block) polyisocyanate compound. The acrylic copolymer is 90 to 50 per total amount of both.
% By weight, preferably in the range of 80 to 60% by weight. If the blending ratio of the acrylic copolymer deviates from the above range, a sufficient crosslinked coating film is not formed and weather resistance, acid resistance,
It is not preferable because the coating film performance such as abrasion resistance deteriorates.

In the coating composition of the present invention, polymer fine particles having an average particle diameter in the range of 0.01 to 1 μm can be blended in addition to the above. The polymer constituting the fine particles must be insoluble in the organic solvent used in the coating composition of the present invention. The polymer may be cross-linked or uncross-linked, but is preferably cross-linked. The fine particles are known per se and can be appropriately selected from conventional ones, and it is particularly preferable to use the following.

(1) Non-aqueous dispersion type vinyl resin The non-aqueous dispersion type vinyl resin is obtained by dispersing and polymerizing at least one vinyl monomer in the presence of a polymer dispersion stabilizer and an organic solvent. As the polymer dispersion stabilizer, known ones conventionally used in the field of non-aqueous dispersion can be used, and examples thereof include the following (1) to (9).

(1) Self-condensed polyester of a hydroxyl group-containing fatty acid such as 12-hydroxystearic acid and glycidyl acrylate or glycidyl methacrylate are added to introduce about 1.0 polymerizable double bonds in the molecule. Polyester macromonomer.

(2) A comb polymer obtained by copolymerizing the polyester macromonomer of the above (1) with methyl methacrylate and / or other (meth) acrylic acid esters and vinyl monomers.

(3) A compound in which a small amount of glycidyl (meth) acrylate is copolymerized with the above (2), and (meth) acrylic acid is later added to the glycidyl group to introduce a double bond.

(4) A hydroxyl group-containing acrylic copolymer obtained by copolymerizing at least 20% by weight of a (meth) acrylic acid ester of a monoalcohol having 4 or more carbon atoms.

(5) According to the above (4), 1 based on the number average molecular weight.
As a method for introducing a double bond of 0.3 or more per molecule, for example, a small amount of glycidyl (meth) acrylate is copolymerized in an original acrylic copolymer, and (G) is added to the glycidyl group later. A method of adding (meth) acrylic acid.

(6) Alkyl melamine resin having a high mineral spirit tolerance.

(7) An alkyd resin having an oil length of 15% or more and / or a method of introducing a polymerizable double bond into the alkyd resin. Examples of a method for introducing a polymerizable double bond include a method of adding glycidyl (meth) acrylate to a carboxyl group in an alkyd resin.

(8) An oil-free polyester resin having a high mineral spirit tolerance, an alkyd resin having an oil length of 15% or more, and / or a resin having a polymerizable double bond introduced therein.

(9) Cellulose acetate butyrate into which a polymerizable double bond has been introduced. Examples of a method for introducing a polymerizable double bond include a method of adding isocyanateethyl methacrylate to cellulose acetate butyrate.

These dispersion stabilizers are used alone or in combination of a plurality of types.

Among the above-mentioned dispersion stabilizers, dispersion stabilizers which are particularly suitable in the present invention are soluble in relatively low-polarity solvents such as aliphatic hydrocarbons, and also satisfy the requirements for coating film performance to some extent. As a dispersion stabilizer satisfying such conditions, particularly, the molecular weight, glass transition temperature, polarity (SP value of polymer), hydroxyl value, acid value, etc. can be easily adjusted, The acrylic copolymers (4) and (5), which are also excellent in weather resistance, are preferred. Further, an acrylic copolymer having an average of about 0.2 to 1.2 polymerizable double bonds capable of graft polymerization with dispersed fine particles in a molecule is preferable.

In the non-aqueous dispersion type vinyl resin used in the coating composition of the present invention, in the presence of the above-mentioned polymer dispersion stabilizer, the dispersion stabilizer and a vinyl monomer which forms dispersed fine particles are dissolved. Polymer fine particles produced from a vinyl monomer are easily produced by dispersing and polymerizing at least one vinyl monomer in an organic solvent mainly containing an aliphatic hydrocarbon which does not substantially dissolve.

The component of the monomer forming the vinyl copolymer suitable as the polymer dispersion stabilizer and the vinyl monomer forming the dispersed fine particles are not particularly limited as long as they are radically polymerizable unsaturated monomers. Various types can be used without any need. Typical examples are as follows.

(A) Ester of acrylic acid or methacrylic acid: for example, methyl acrylate, ethyl acrylate,
Propyl acrylate, isopropyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, lauryl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, methacrylic acid Hexyl, octyl methacrylate, lauryl methacrylate, stearyl methacrylate, etc., C _1-18 alkyl esters of acrylic acid or methacrylic acid: glycidyl acrylate, glycidyl methacrylate: allyl acrylate, C _2- of acrylic acid, such as allyl methacrylate, or methacrylic acid ₈ alkenyl esters: hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl meth click relay Acrylic or C _2-8 hydroxyalkyl esters of methacrylic acid equal allyl oxyethyl acrylate, C _3-18 alkenyloxy alkyl esters of acrylic acid or methacrylic acid such as allyl methacrylate or the like.

(B) Vinyl aromatic compounds: for example, styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, vinylpyridine and the like.

(C) α, β-ethylenically unsaturated acid: for example, acrylic acid, methacrylic acid, itaconic acid and the like.

(D) Amide of acrylic acid or methacrylic acid: for example, acrylamide, methacrylacrylamide, n-butoxymethylacrylamide, n-methylolacrylamide, n-butoxymethylmethacrylamide, n-methylolmethacrylamide and the like.

(E) Others: For example, acrylonitrile, methacrylonitrile, methyl isopropenyl ketone; vinyl acetate, veoba monomer (manufactured by Shell Chemical Company),
Vinyl propionate, vinyl pivalate, isocyanate ethyl methacrylate, perfluorocyclohexyl (meth) acrylate, p-styrenesulfonamide, N-methyl-p-styrenesulfonamide, γ-methacryloxypropyltrimethoxysilane and the like.

Among the above-mentioned monomers, those which are preferably used particularly for the preparation of a vinyl copolymer as a dispersion stabilizer include n-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, lauryl methacrylate. , Mainly composed of relatively long-chain low-polar monomers such as stearyl methacrylate, and, if necessary, styrene, methyl (meth) acrylate, ethyl (meth) acrylate,
It is a monomer mixture using 2-hydroxyethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid and the like in combination.

It is preferable that glycidyl (meth) acrylate or isocyanatoethyl methacrylate is added to a polymer obtained by copolymerizing these monomers to introduce a polymerizable double bond.

The vinyl copolymer serving as a dispersion stabilizer can be easily produced by a conventionally known solution polymerization method using a radical polymerization initiator.

The number average molecular weight of the dispersion stabilizer is 1,000.
About 50,000 to 3,000 to 3,000.
A range of about 0000 is more preferable.

Among the above-mentioned monomers, those which are particularly suitable as vinyl monomers forming dispersed fine particles include:
It is mainly composed of relatively high polar monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl acrylate, and acrylonitrile, and if necessary, (meth) acrylic acid and (meth) acrylic acid. Those using 2-hydroxyethyl acrylate in combination can be mentioned. Also, a small amount of a polyfunctional monomer such as divinylbenzene or ethylene glycol dimethacrylate is used in combination, or a plurality of monomers having a functional group that react with each other such as glycidyl methacrylate and methacrylic acid are copolymerized or N-alkoxymethylated. The inside of the particles may be crosslinked by copolymerizing a self-reactive monomer such as acrylamide or γ-methacryloxy trialkoxysilane to form gelled particles.

In carrying out the dispersion polymerization, the mixing ratio of the dispersion stabilizer and the vinyl monomer to be dispersed fine particles is as follows:
5/95 to 80/20 by weight ratio, preferably 10/90
The dispersion polymerization may be carried out in the presence of a radical polymerization initiator according to a conventionally known method.

(2) Other polymer fine particles Obtained by subjecting a monomer mixture containing a crosslinking monomer containing at least two ethylenic double bonds to emulsion polymerization in an aqueous medium using an anionic or nonionic surfactant. An aqueous dispersion of polymer fine particles may be used in the form of a powder in which polymer fine particles are separated from the aqueous dispersion, or a dispersion of an organic solvent obtained by replacing water with an organic solvent.

The above aqueous dispersion is described in, for example,
In the gelled fine particle polymer and the method for producing the same described in Japanese Patent No. 47107, those using an anionic or nonionic reactive emulsifier can be suitably used.
Since the gelled fine particle polymer is described in the publication, the detailed description will be replaced with this reference here.

By using the polymer fine particles in the coating composition of the present invention, a coating film having further excellent appearance and durability can be formed.

The mixing ratio of the polymer fine particles can be appropriately selected depending on the required performance and the like, but is usually about 100 parts by weight based on the total weight of the acrylic copolymer, amino resin and (block) polyisocyanate compound. The range is 0.1 to 50 parts by weight, preferably about 1 to 30 parts by weight.

In the coating composition of the present invention, a small amount of a modified resin such as cellulose acetate butyl, epoxy resin, polyester resin, alkyd resin and acrylic resin may be used in addition to the above components. If necessary, additives such as an organic solvent, a pigment, a curing catalyst, an ultraviolet absorber, a coating surface adjuster, an antioxidant, a fluidity adjuster, a pigment dispersant, and a silane coupling agent may be added. Can be.

Examples of the organic solvent include hydrocarbon solvents such as heptane, toluene, xylene, octane, and mineral spirit; and ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, methyl cellosolve acetate, and butyl carbitol acetate. , Methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and other ketone solvents; methanol, ethanol, isopropanol, n-butanol, sec-butanol, isobutanol, and other alcohol solvents, n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol Ethers such as monoethyl ether,
Aromatic petroleum solvents such as Swazol 310, Swazol 1000, and Swazol 1500 manufactured by Cosmo Oil Co., Ltd. can be used. These organic solvents can be used alone or in combination of two or more. Further, from the viewpoint of curability, those having a boiling point of about 150 ° C. or less are preferable, but not limited thereto.

Examples of the pigments that may be contained in the coating composition of the present invention include organic pigments (for example, quinacridones such as quinacridone, azos such as pigment red, and phthalocyanines such as phthalocyanine blue and phthalocyanine green) and inorganic pigments. Pigments (eg, titanium oxide, barium sulfate, calcium carbonate, barita, clay, silica, etc.),
Carbon-based pigments (carbon black), metallic powders (eg, aluminum, mica-like iron oxide, stainless steel, etc.) and rust preventive pigments (eg, red iron, strontium chromate, etc.) can be used.

As a curing catalyst, a curing agent (block)
When it is a polyisocyanate compound, examples thereof include dibutyltin diacetate, dibutyltin dioctate, dibutyltin laurate, triethylamine, and diethanolamine.

The coating composition of the present invention can be applied directly to a material to be coated such as metal (for example, steel plate, surface-treated steel plate, etc.), plastic or the like, or to the surface of a coating film obtained by applying a primer or primer / intermediate coating to the material to be coated. . When used as an automotive paint, for example, it can be used as a top coat enamel paint such as 2 coats 1 bake, 2 coats 2 bake, etc. and a solid color paint such as a clear top coat paint and 1 coat 1 bake.

The coating composition of the present invention is applied to a dry film thickness of about 10 to 60 μm by means of, for example, electrostatic coating (bell type or the like), air spray coating or the like, and is applied at a temperature of about 120 to 180 ° C. for 10 to 60 μm. By heating for about a minute, a coating film can be formed.

When the paint composition of the present invention is used as a clear top coat paint such as the above two coat one bake, two coat two bake, etc., additives such as an ultraviolet absorber, an ultraviolet stabilizer and the like may be blended. Is preferred.

Specific examples of the ultraviolet absorber include benzophenone, 2,4-dihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone,
2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy -4-methoxy-5-sulfobenzophenone, 5-chloro-2-hydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2-hydroxy-4-
Benzophenone-based compounds such as methoxy-2'-carboxybenzophenone, 2-hydroxy-4- (2-hydroxy-3-methylacryloxy) propoxybenzophenone; 2- (2'-hydroxy-5'-methyl-phenyl) benzo Triazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butyl-phenyl) benzotriazole, 2- (2'-hydroxy-3'-te
rt-butyl-5'-methyl-phenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t
tert-butyl-phenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t
tert-isoamylphenyl) benzotriazole,
2- (hydroxy-5-tert-butyl-phenyl)
Benzotriazole-based compounds such as benzotriazole; ethyl-2-cyano-3,3'-diphenylacrylate, 2-ethylhexyl-2-cyano-3,3'-
Acrylates such as diphenyl-acrylate; salicylates such as phenyl salicylate, 4-tert-butyl-phenyl salicylate, para-octyl-phenyl salicylate; ethanediamide-N- (2-
Ethoxyphenyl) -N ′-(4-isododecylphenyl), 2-ethyl-2′-ethoxyoxalanilide,
2-ethoxy-5-tert-butyl-2'-ethyl-
Oxalanilide and Sandboes EPU. Oxalic anilide compounds such as USU 3206; hydroxy-5-methoxy-acetophenone;
2-hydroxy-naphthophenone, 2-ethoxyethyl-para-methoxycinnamate, nickel-bisoctylphenyl sulfide, [2,2'-thiobis (4-t
ert-octylphenolato)]-n-butylamine-
Other compounds such as nickel are exemplified. These can be used alone or in combination of two or more.

As the ultraviolet stabilizer, bis (1,2,2,3)
2,6,6-pentamethyl-4-piperidinyl) -2-
Butyl-2- (4-hydroxy-3,5-di-tert
-Butylbenzyl) propane diate, bis (1,
2,2,6,6-pentamethyl-4-piperidyl) sebacate, 8-acetyl-3-dodecyl-7,7,9,9
-Tetramethyl-1,3,8-triazaspiro [4,
5] Decane-2,4-dione and Tinuvin 144, 292, 440 (trade names, manufactured by Ciba Geigy) as trade names,
Hindered amines such as SANOL LS-770 (manufactured by Sankyo Co., Ltd.) are exemplified.

The above-mentioned ultraviolet absorber can be used alone, but in the present invention, it is particularly preferable to use this in combination with an ultraviolet stabilizer. These additives are desirably in the range of about 0.1 to 4 parts by weight per 100 parts by weight of the total weight of the additive and the vinyl copolymer crosslinking agent.

The clear coating is usually used without adding a coloring pigment, but a coloring pigment that does not hide the colored base coating film can be added to the clear coating.

Next, the above-described two-coat one-bake will be described. The two-coat and one-bake can be carried out, for example, by applying a paint composition for a colored base coat to the above-mentioned material, and then applying and baking the paint for a clear top coat. The coating of the coating composition for the coloring base and the clear top coat can be carried out by a usual coating method, for example, an electrostatic coating or a non-electrostatic coating machine. The thickness of the colored base coat is preferably about 10 to 50 μm (after curing). After applying the paint, leave it at room temperature for several minutes or
After forcibly drying at about 0 to 80 ° C. for several minutes, a clear coat paint composition is applied. Clear film thickness is 10-6
0 μm (after curing) is preferred. Then 120-180 ° C
The heating is performed at a temperature of about 10 to 40 minutes.

The above-mentioned colored base coat application composition is preferably a curable coating composition containing a metal flake powder and / or a mica powder, and such a colored base coating itself is already known. Specifically, an acrylic resin, a polyester resin, an acryl / polyester resin or the like is used as a base resin, an amino resin, a (block) polyisocyanate or the like is used as a cross-linking agent, and if necessary, cellulose acetate butyrate, a coloring pigment, an extender pigment, Organic solvent-based (including high solid and non-aqueous dispersion type) paints containing organic polymer fine particles, anti-settling agent, anti-sagging agent, pigment dispersant, UV absorber and other paint additives, water-based Curable paints such as paints can be used. Examples of the metal flake powder include aluminum flake, nickel flake, copper flake, stainless flake, brass flake and chrome flake, and examples of the mica powder include pearl mica, colored pearl mica, and the like.

[0066]

In the coating composition of the present invention, the acrylic copolymer which is a cured resin component contains a styrene monomer as a main component particularly as a monomer component constituting the copolymer, and is copolymerized with the styrene monomer. By selecting an acrylate monomer as a monomer component to be polymerized, a coating film having excellent weather resistance and acid resistance can be formed. The reason for exhibiting such an excellent effect is that the radical copolymerization reactivity between the styryl group of the styrene monomer and the acryloyl group of the acrylate ester monomer used in the present invention is good, so that the amount of the styrene homopolymer is small. A copolymer has been synthesized, and the weather resistance of a coating film can be greatly improved, which is not expected from an acrylic resin containing 45 to 55% by weight of a styrene monomer. It is presumed that was able to form a coating film having excellent acid resistance, which is chemically stable because it is hardly affected by acid or the like.

Further, in the coating composition of the present invention, as a monomer component constituting the acrylic copolymer, 1,4-
Butanediol monoacrylate monomer and / or ε
-By using a hydroxyl group-containing monoacrylate monomer as the caprolactone-modified acrylate monomer, it is possible to uniformly introduce a primary hydroxyl group into the acrylic copolymer molecule, and to have excellent scratch resistance due to the properties of the monomer component itself. It has the effect of forming a cured coating film.

[0068]

EXAMPLES The present invention will be further clarified with reference to Production Examples, Examples and Comparative Examples. Unless otherwise specified, “parts” and “%” are “parts by weight” and “% by weight”, respectively.
Means

[1] Preparation of Sample Production Example 1 Production of Hydroxy Group-Containing Acrylic Resin Solution A Swazol 1000 [manufactured by Cosmo Oil Co., Ltd.] was placed in a usual acrylic resin reaction tank equipped with a stirrer, thermometer, reflux condenser and the like. , Aromatic solvent], and the mixture was heated and stirred. After the temperature reached 125 ° C., the following monomer mixture was added dropwise over 3 hours.

Styrene 50 parts Lauryl acrylate 10 parts n-butyl acrylate 7 parts 1,4-butanediol monoacrylate 30 parts Acrylic acid 3 parts α, α'-azobisisobutyronitrile 4 parts The above monomer mixture is added dropwise. After completion, further 30 minutes at 125 ° C
Azobisdimethylvaleronitrile 0.5
And a mixture of 20 parts of Swazole 1000 were added dropwise over 1 hour. Thereafter, stirring was continued for 1 hour while maintaining the temperature at 125 ° C., followed by cooling. Add n-butanol to this
4.8 parts were added and diluted to obtain a hydroxyl group-containing acrylic resin A having a solid content concentration of 55%. The weight average molecular weight (MW) of this acrylic resin was 13,000, and the benzene ring concentration in the acrylic resin (the concentration of benzene rings with respect to the total amount of the monomer components) was 37%. The benzene ring concentration in the acrylic resin was determined by the following equation.

[0071]

(Equation 1)

Production Examples 2 to 7 Production of Hydroxy Group-Containing Acrylic Resin Solutions B to G Acrylic resin solutions B to G were produced in the same manner as in Production Example 1. All solids concentrations were 55% by weight. Compositions of Acrylic Resin Solutions BG and Their Weight Average Molecular Weights (M
W) is shown in Table 1.

[0073]

[Table 1]

Production Example 8 Production of Non-Aqueous Dispersion-Type Vinyl Resin A conventional acrylic resin reaction tank equipped with a stirrer, thermometer, reflux condenser, etc. was charged with 45.7 parts of xylol and 5 parts of n-butanol. After heating and stirring and reaching 125 ° C., the following monomer mixture was added dropwise over 3 hours.

Styrene 30 parts Lauryl methacrylate 20 parts n-butyl acrylate 10 parts 2-ethylhexyl methacrylate 12 parts 2-hydroxyethyl methacrylate 20 parts 2-hydroxyethyl acrylate 5 parts Acrylic acid 3 parts tert-butyl peroctoate 4.6 parts After dropping the above monomer mixture, the mixture is further heated at 125 ° C. for 30 minutes.
Azobisdimethylvaleronitrile 0.5
And a mixture of 16 parts of xylol were added dropwise over 1 hour, and the mixture was aged for 5 hours. The solid content of the obtained resin solution was 60%.

Next, 168 parts of the varnish was added to 4-ter
0.03 parts of t-butyl pyrocatechol and 2 parts of glycidyl methacrylate were added and reacted at 125 ° C. for 5 hours to introduce a polymerizable double bond. 90 parts of this product, 48 parts of xylol and 105 parts of heptane were charged into a flask, and the following monomers and a polymerization initiator were added dropwise at 90 ° C. over 4 hours. Further, 0.5 part of tert-butyl peroctoate was added, followed by aging for 3 hours to obtain a non-aqueous dispersion type vinyl resin.

Styrene 40 parts Methyl methacrylate 20 parts Acrylonitrile 16 parts Glycidyl methacrylate 2 parts 2-hydroxyethyl acrylate 20 parts Methacrylic acid 2 parts α, α'-azobisisobutyronitrile 1 part The obtained resin dispersion has a solid content. 45% milky white dispersion.

Production Example 9 Production of Gelled Fine Particles 1 equipped with a stirrer, thermometer, cooling pipe and heating mantle
In one flask, 3536.5 parts of deionized water, emulsifier (*
51 parts of 1) was added and the temperature was raised to 90 ° C. while stirring.
12.5 parts of the polymerization initiator (* 2) was added to 50 parts of deionized water.
20% of an aqueous solution dissolved in 0 parts was added. After 15 minutes, 5% of the monomer mixture (* 3) was added. Then another 30
After stirring for 1 minute, the remaining monomer mixture and the polymerization initiator were started to be dropped. The drop of the monomer mixture was 3 hours,
The polymerization initiator was added dropwise over 3.5 hours, during which the polymerization temperature was kept at 90 ° C. After completion of the dropwise addition of the polymerization initiator aqueous solution, the mixture was heated at 90 ° C. for 30 minutes, cooled to room temperature, and taken out using a filter cloth to obtain an aqueous dispersion of an aqueous gelled fine particle polymer having a solid content of 20%.

The obtained aqueous dispersion was dried on a stainless steel vat in an electric hot air dryer at 60 ° C., and was taken out as a solid resin. Thereafter, the mixture was dispersed in a mixed solvent of xylene / n-butyl alcohol = 50/50 (weight ratio) heated to 60 ° C. to obtain a gelled fine particle polymer dispersion (average particle diameter 82 nm) having a solid content concentration of 20%. Prepared.

* 1 Emulsifier: Eleminor JS-2
(39% aqueous solution) Sulfosuccinic allyl group-containing anionic reactive emulsifier, commercial product, Sanyo Chemical.

* 2 Polymerization initiator: VA-080 Water-soluble azoamide polymerization initiator 2,2′-azobis ｛2
-Methyl-N- [1,1-bis (hydroxymethyl)-
2-Hydroxyethyl] propionamide｝, commercial product
Wako Pure Chemical Industries.

* 3 Monomer mixture: styrene / n-butyl acrylate / 1,6-hexanediol acrylate = 470/470/60 (parts).

Example 1 The hydroxyl-containing acrylic resin solution (A) obtained in Production Example 1 was
A mixture of 36 parts (75 parts by solid content), 25 parts of Cymel XV805 (Note 1), 0.1 part of a surface preparation agent (Note 2), and 2 parts of an ultraviolet absorber (Note 3) is stirred, and then Swazole 1500 is used. (Note 4) A mixed solvent of / n-butanol = 9/1 was added and the paint viscosity was 25 seconds (Ford cup # 4/25
° C) for the test.

(Note 1) Cymel XV805: A methyl and isobutyl mixed etherified monomeric melamine resin having a solid content of about 100%, manufactured by Mitsui Cyanamid Co., Ltd.

(Note 2) Surface preparation agent: Big Chem Co., Ltd., B
YK-300 solution,

(Note 3) UV absorber: Tinuvin 900 manufactured by Ciba-Geigy.

(Note 4) Swazol 1500: an aromatic solvent manufactured by Cosmo Oil Co., Ltd.

Examples 2 to 7 and Comparative Examples 1 to 3 were carried out in the same manner as in Example 1 except that the mixture before adjusting the viscosity was as shown in Table 2, and each had a coating viscosity of 25 seconds (Ford cup # 4 / (25 ° C.).

The mixing ratios of the examples and comparative examples in Table 2 are amounts (parts) converted into the solid content and the active ingredient.

(Note) in Table 2 is as follows.

(Note 5) Nailure 5543: manufactured by Industries, King, USA, a neutralized dodecylbenzenesulfonate amine having an active ingredient of about 25%, trade name.

(Note 6) Sumidur N: non-yellowing type polyisocyanate (NCO, manufactured by Sumitomo Bayer Urethane Co., Ltd.)
Content 16.5%, solid content concentration 75%).

[0093]

[Table 2]

[0094]

[Table 3]

Comparative Study Example The hydroxyl group-containing acrylic resin (A) obtained in Production Example 1 and the hydroxyl group-containing acrylic resin (E) obtained in Production Example 5 were combined with a UV detector (ultraviolet spectrophotometer, a benzene ring at a wavelength of 254 nm). The results of analysis of both acrylic resins using GPC (gel permeation chromatography) equipped with detection) are shown in FIGS. 1 and 2, respectively. From these figures, the distribution state of styrene in each polymer can be observed. In the acrylic resin (A), almost no styrene-rich oligomer exists in the low molecular weight region (MW 2,000 or less). On the other hand, when a large amount of styrene and methacrylic acid ester are copolymerized as in the case of the acrylic resin (E), it can be seen that a considerable amount of styrene-rich oligomer exists in the low molecular weight region. From these results, it is apparent that by copolymerizing styrene and acrylate as in the present invention, it is possible to suppress the formation of low molecular weight styrene-rich oligomers, which is one of the adverse factors affecting weather resistance. .

Coating and Preparation of Coated Films The coated and cured coating films were prepared by using the viscosity-adjusted coating materials of the above Examples and Comparative Examples.

0.8 mm thick with zinc phosphate chemical conversion treatment
An epoxy-based cationic electrodeposition paint is electrodeposited on a dull steel plate so as to have a dry coating of about 20 μm, and an automobile middle coating surfacer is applied on the baked electrodeposition coating with a dry coating thickness of about 20 μm.
After coating and baking to a thickness of μm, the material was sanded with # 400 sandpaper, drained and dried, and then degreased with petroleum benzene to prepare a test material.

[0098] On this material, Magiclon base coat HM
-22 (manufactured by Kansai Paint Co., Ltd., metallic paint, trade name)
Was coated using an air spray gun F5 (trade name, manufactured by Meiji Kikai Seisakusho) so as to have a cured film thickness of about 15 μm, and was left at room temperature for about 3 minutes. The paint whose viscosity was adjusted was applied using the above-mentioned air spray gun F5 so as to have a cured film thickness of about 40 μm, and then left standing at room temperature for about 10 minutes.
Next, this was heated and cured at 140 ° C. for 30 minutes using an electric hot air dryer.

Example 1 was used to measure the gel fraction.
To 7 and Comparative Examples 1 to 3 were cured to a thickness of about 40 μm on a tin plate.
m.

Various tests were carried out on each of the obtained baked coated plates. Table 3 shows the test results.

[0101]

[Table 4]

The tests in Table 3 were performed according to the following test methods.

Test Method Coating Appearance: The finished appearance of the coating film was evaluated based on the following criteria based on glossiness and stickiness. ◎: very good, ：: good, ×: bad.

20 ° gloss: Specular reflectance was measured at 20 °.

Pencil hardness: A pencil scratch value according to JIS K 5400 was displayed.

Acid resistance: 0.4 ml of artificial rain was dropped on a test coated plate, heated on a hot plate heated to 85 ° C. for 15 minutes, washed with water, and the coated surface was observed and evaluated according to the following criteria. ：: No change at all, Δ: No abnormality on the painted surface, but a slight step was recognized at the boundary between the dripped portion and the non-dripped portion, ×: Whitened painted surface.

As artificial rain, 19.6 g of a 1 mg / g solution of NaNO ₃ , 5.2 g of a 1 mg / g solution of KNO ₃ ,
₂ · 2H ₂ O 1mg / g solution 3.7g, MgSO ₄ · 7
8.2 g of a 1 mg / g solution of H ₂ O, 1 m of (NH ₄ ) ₂ SO ₄
g / g solution, 73.3 g, 0.1N H ₂ SO ₄ .
0 g, 20.0 g of 0.1 N HNO ₃ , 0.05 NH
A mixture of 10.0 g of Cl and 4.7 g of a 1 mg / g solution of NaF and adjusted to 1 with H ₂ SO ₄ was used.

Water resistance: After being immersed in warm water of 40 ° C. for 240 hours, it was washed with water, the coated surface was observed, and evaluated according to the following criteria. ○: no change at all, △: slightly glossy.

Solvent resistance: The coated surface was wiped 10 times with gauze impregnated with xylol, and the coated surface was observed and evaluated according to the following criteria. ：: No change at all, Δ: Scratch on the coated surface, ×: Swelled coated surface and whitening tendency.

Scratch resistance: After the automobile coated with the test coated plate on the roof was washed 5 times with a car washer, the coated surface of the coated plate was observed. Car wash machine made by Yasui Sangyo "PO 20FW"
RC "was used. The evaluation criteria are as follows. ：: Almost no scratches were found by visual observation, and passed.
：: Slight scratches are found, but the degree is light. △: Scratches are conspicuous by visual observation and reject. ×: Marked scratches are clearly recognized by visual observation and reject.

Gel fraction: 3 coating films peeled from tin plate
After placing in a 00 mesh stainless steel mesh container and extracting with an acetone / methanol = 1/1 solvent for 6 hours, the gel fraction was calculated according to the following equation. Gel fraction (%) = (weight of sample after extraction / weight of sample before extraction) × 100

Weather resistance: The coating film after being exposed to a sunshine weather meter for 1600 hours was observed and evaluated as follows. ：: no abnormality, △: small cracks occurred a little, ×: cracks.

[Brief description of the drawings]

FIG. 1 shows a hydroxyl group-containing acrylic resin (A) obtained in Production Example 1.
Is the result of analyzing by GPC.

FIG. 2 is a hydroxyl group-containing acrylic resin (E) obtained in Production Example 5.
Is the result of analyzing by GPC.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masaaki Kobayashi 4-171-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Inside Kansai Paint Co., Ltd. (72) Inventor Adult 4-1-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Paint Examiner, Tsutomu Onodera, Inc. (56) References JP-A-1-158079 (JP, A) JP-A-3-172368 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09D 1/00-201/10

Claims (3)

(57) [Claims] 1. The following component (A): a hydroxyl value of 60 to 14, which is composed of a styrene monomer, a hydroxyl group-containing monoacrylate monomer and an acrylate monomer of a monohydric alcohol having 4 to 24 carbon atoms.
0 mgKOH / g resin, weight average molecular weight 3,000-30,0
Acrylic copolymer 90 to 50 wherein the styrene monomer content is 45 to 55% by weight
% By weight (B) 10 to 50% by weight of an amino resin and / or a (block) polyisocyanate compound as a curable resin composition. 2. The coating composition according to claim 1, comprising a 1,4-butanediol monoacrylate monomer and / or an ε-caprolactone-modified acrylate monomer as the hydroxyl group-containing monoacrylate monomer. 3. The coating composition according to claim 1, wherein the coating composition is a top coating composition.