WO2015037280A1

WO2015037280A1 - Coating material composition and coated article

Info

Publication number: WO2015037280A1
Application number: PCT/JP2014/063892
Authority: WO
Inventors: 正人中水
Original assignee: 関西ペイント株式会社
Priority date: 2013-09-10
Filing date: 2014-05-26
Publication date: 2015-03-19
Also published as: CN105612227B; JP5692482B1; JPWO2015037280A1; CN105612227A

Abstract

This coating material composition contains a base material that contains a hydroxyl group-containing acrylic resin (A) and a curing agent that contains a polyisocyanate compound (B). The hydroxyl group-containing acrylic resin (A) contains 25-95 parts by mass of a hydroxyl group-containing acrylic resin (A1) that has a hydroxyl number of 70-200 mgKOH/g and a glass transition temperature of less than -30°C and 5-75 parts by mass of a hydroxyl group-containing acrylic resin (A2) that has a hydroxyl number of 30-200 mgKOH/g and a glass transition temperature of from -30°C to 75°C based on the mass of the resin solids in the base material. The hydroxyl group-containing acrylic resin (A2) has a specific monomer composition.

Description

Coating composition and coated article

The present invention relates to a coating composition and a coated article that can form a coating film having excellent scratch resistance, hardness, appearance, adhesion, and chemical resistance to a plastic substrate.

In recent years, plastic base materials such as ABS resin, polypropylene, urethane resin, and polycarbonate resin have been used for various industrial products such as communication devices, home appliances, and automobile parts. Such industrial products are required to have scratch resistance, hardness, appearance, adhesion, chemical resistance, and the like.

For various industrial products, the first layer is coated with multiple types of paints with different functions, such as the paint with excellent adhesion to the substrate and the second layer with excellent scratch resistance of the substrate. There are industrial products that can form multi-layer coatings, but in some cases, it is possible to establish adhesion and various coating film performances in the coating process of one coat and one bake (one coating and one baking) with one type of paint. Some industrial products are required, and it is more difficult to find one coat and one bake as a problem. In addition, as chemical resistance, in recent years, it contains UV absorbers, preservatives, emulsifiers and the like such as liquid foundations, makeup foundations, concealers, sunscreens, cosmetics such as cosmetic liquids, milky lotions and hand creams. Even if the composition for external use on the skin is left on the surface of the coating, it does not cause poor coating adhesion, reduced appearance, reduced hardness, etc. (hereinafter abbreviated as “resistance to a composition containing an ultraviolet absorber”). Is sometimes required).

For example, Patent Document 1 discloses a clear coating composition containing a hydroxyl group-containing acrylic resin and a polyfunctional isocyanate compound as a paint excellent in scratch resistance and acid resistance, wherein the hydroxyl group-containing acrylic resin is at least part of a monomer. As a hydroxyl group-containing acrylic resin obtained using a hydroxyalkyl (meth) acrylate having a hydroxyalkyl group having 4 to 9 carbon atoms, wherein at least a part of the polyfunctional isocyanate compound is an isocyanurate type isocyanate compound, A lactone-containing monomer having a specific soft segment portion in an amount of 25 to 50% by mass based on the total solid content of the hydroxyl group-containing acrylic resin and polyfunctional isocyanate compound, and based on the total solid content of the hydroxyl group-containing acrylic resin and polyfunctional isocyanate compound Soft seg of origin A clear coating composition for automobiles, wherein the proportion of the tip portion is 4.5% by mass or less and the resulting cured coating film has a dynamic glass transition temperature in the range of 30 to 60 ° C. A composition is disclosed.

However, the paint is mainly suitable for a metal substrate, and adhesion to a plastic substrate in a 1-coating 1-baking process and resistance to a composition containing an ultraviolet absorber are not sufficient.

In Patent Document 2, as a paint excellent in car washing scratch resistance, acid resistance and weather resistance, the hydroxyl value is 80 to 220 mgKOH / g, the glass transition temperature is −50 ° C. or higher and lower than 0 ° C. A hydroxyl group-containing resin (A) containing 25 to 55% by mass of units derived from hydroxybutyl (meth) acrylate, a hydroxyl group value having a hydroxyl value of 80 to 220 mgKOH / g and a glass transition temperature of 0 to 50 ° C. A coating composition comprising a resin (B) and a crosslinking agent (C) comprising a polyisocyanate compound as essential components, wherein the content ratio of the hydroxyl group-containing resin (A) and the hydroxyl group-containing resin (B) is a resin solid Isocyanate having a mass ratio of 95/5 to 50/50 and a functional group of the crosslinking agent (C) for the total hydroxyl groups of the hydroxyl group-containing resin (A) and the hydroxyl group-containing resin (B) Content of coating composition is disclosed, wherein the molar ratio of NCO / OH is 0.5 to 1.5.

However, the paint is mainly suitable for a metal substrate, and adhesion to a plastic substrate in a 1-coat 1-bake coating process and resistance to a composition containing an ultraviolet absorber are not sufficient.

Patent Document 3 discloses a self-restoring coating composition containing a lactone-modified acrylic resin and a polycarbonate diol. Although the said coating resin composition is excellent in the abrasion resistance to the ABS board in the 1 coat 1 baking process, the tolerance with respect to the composition containing a ultraviolet absorber etc. is not enough.

Patent Document 4 discloses that a polyisocyanate compound (A) having an isocyanate group equivalent in the range of 100 to 280 g / eq and an average glass transition temperature (Tg) of −55 ° C. or more and less than −9 ° C. And an acrylic polyol (B) having an average functional group number of 4 to 20 and a number average molecular weight (Mn) in the range of 3000 to 15000, the ratio of both [the number of moles of isocyanate groups in the polyisocyanate compound] ] / [The number of moles of hydroxyl groups in the acrylic polyol (B)] is contained in such a ratio that it is in the range of 0.75 to 1.5. Although the said coating resin composition is excellent in the scratch resistance to the ABS board in a 1 coat 1 baking coating process, and base-material adhesiveness, the tolerance with respect to the composition containing a ultraviolet absorber etc. is not enough.

Patent Document 5 discloses a polyisocyanate compound (A) having an isocyanate group equivalent of 100 to 280 g / eq, an average Tg of −50 to −10 ° C., and an average number of functional groups of hydroxyl groups per molecule of 4 to Polyester polyol (B) having a number average molecular weight (Mn) in the range of 1000 to 3000 and a ratio of the two [molar number of isocyanate groups in the polyisocyanate compound] / [polyester polyol (B) A coating resin composition is disclosed, which is contained in such a ratio that the number of moles of the hydroxyl group in the range of 0.75 to 1.5. The coating resin composition is excellent in scratch resistance and substrate adhesion to an ABS plate in a 1-coat 1-bake coating process, but is not sufficiently resistant to a composition containing an ultraviolet absorber or the like.

Patent Document 6 describes chemical resistance, for example, a lotion used to prevent sunburn, and the surface of the acrylic resin film does not become rough even if it is exposed to a high temperature for a long time with a hand cream attached. When molded, the film surface does not crack, and has a surface hardness, and has a carboxyl group and a hydroxyl group, and has a solid content acid value of 15 to 150 mgKOH / g and a glass transition temperature. Containing a vinyl polymer (A) having a temperature of 70 to 140 ° C. and a polyisocyanate compound (B), wherein the polyisocyanate compound (B) has a solid content hydroxyl value of 2 to 2 in the vinyl polymer (A). A curable resin composition for a thermoforming film characterized by a content that reacts with 80 mg KOH / g is disclosed. However, the curable resin composition for thermoforming film is not sufficient in adhesion to a plastic substrate and scratch resistance in a 1-coat 1-bake coating process.

Japanese Unexamined Patent Publication No. 2006-176634 Japanese Unexamined Patent Publication No. 2009-46642 Japanese Unexamined Patent Publication No. 2012-97127 Japanese Unexamined Patent Publication No. 2012-97173 Japanese Unexamined Patent Publication No. 2012-87183 Japanese Unexamined Patent Publication No. 2012-97248

The present invention has been made in consideration of these points, and contains excellent scratch resistance, hardness, appearance, adhesion, ultraviolet absorbers and the like for a plastic substrate in a 1-coat 1-bake coating process. It is an object of the present invention to provide a coating composition and a coated article capable of forming a coating film having resistance to the composition.

As a result of intensive studies to achieve the above object, the present inventor has obtained a paint containing a main agent containing two specific hydroxyl group-containing acrylic resins at a specific ratio and a curing agent containing a polyisocyanate compound. It has been found that the above problems can be solved by using the composition, and the present invention has been completed.

That is, the present invention provides the following coating composition and an article obtained by coating the coating composition.
The present invention relates to the following (1) to (6).
(1) A coating composition comprising a main agent containing a hydroxyl group-containing acrylic resin (A) and a curing agent containing a polyisocyanate compound (B),
The hydroxyl group-containing acrylic resin (A) has a hydroxyl value of 70 to 200 mgKOH / g and a glass transition temperature of less than −30 ° C. of 25 to 95 parts by mass based on the resin solid mass in the main agent, and 5 to 75 parts by mass of a hydroxyl group-containing acrylic resin (A2) having a hydroxyl value of 30 to 200 mg KOH / g and a glass transition temperature of -30 to 75 ° C.
And,
The hydroxyl group-containing acrylic resin (A2) is based on the total amount of the polymerizable unsaturated monomers (a2-1) to (a2-3).
30-80% by mass of methyl methacrylate (a2-1),
Hydroxyl-containing polymerizable unsaturated monomer (a2-2) 10 to 35% by mass, and other polymerizable unsaturated monomer (a2-3) 0 to 60% by mass
The coating composition which is a hydroxyl-containing acrylic resin obtained by making this react.
(2) The hydroxyl group-containing acrylic resin (A1) is based on the total amount of the polymerizable unsaturated monomers (a1-1) and (a1-2).
10 to 60% by mass of polymerizable unsaturated monomer (a1-1) having a hydroxyalkyl group having 4 to 9 carbon atoms and 40 to 90% by mass of other polymerizable unsaturated monomer (a1-2)
The coating composition according to (1) above, which is a hydroxyl group-containing acrylic resin obtained by reacting
(3) The coating composition according to (1) or (2), wherein the polyisocyanate compound (B) is at least one selected from the group consisting of biuret type and allophanate type polyisocyanate compounds.
(4) The coating composition according to any one of (1) to (3), wherein the main agent further contains a hydroxyl group-containing polyester resin (C).
(5) A method of applying the coating composition according to any one of (1) to (4) on a plastic substrate surface.
(6) A coated article obtained by coating the plastic substrate surface with the coating composition according to any one of (1) to (4).

The coating composition of the present invention has excellent scratch resistance, hardness, appearance, adhesion, and resistance to a composition containing an ultraviolet absorber, etc., for a plastic substrate in a 1-coat 1-bake coating process. A coating film can be formed.

Hereinafter, the coating composition of the present invention will be described in more detail.
In the present specification, “mass” means “weight”.

The coating composition of the present invention is a coating composition comprising a main component containing a hydroxyl group-containing acrylic resin (A) and a curing agent containing a polyisocyanate compound (B), wherein the hydroxyl group-containing acrylic resin (A) is The specific hydroxyl group-containing acrylic resin (A1) and the specific hydroxyl group-containing acrylic resin (A2) are contained in a specific ratio based on the resin solid content mass in the main agent.

(Main agent)
<Hydroxyl-containing acrylic resin (A)>
In the present invention, the hydroxyl group-containing acrylic resin (A) refers to an acrylic resin containing a hydroxyl group in the molecule. The hydroxyl group-containing acrylic resin (A) can be synthesized by copolymerizing a hydroxyl group-containing polymerizable unsaturated monomer and other copolymerizable polymerizable unsaturated monomers by a conventional method.

Examples of the hydroxyl group-containing polymerizable unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and polyethylene glycol. Ε-caprolactone is added to a monoesterified product of a polyhydric alcohol such as mono (meth) acrylate or polypropylene glycol (meth) acrylate and (meth) acrylic acid, or a monoesterified product of the polyhydric alcohol and (meth) acrylic acid. Examples thereof include compounds obtained by ring-opening polymerization, and these can be used alone or in combination of two or more.

Other copolymerizable polymerizable unsaturated monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, Isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-octyl (meth) acrylate, nonyl ( Alkyl esters of (meth) acrylic acid such as (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, stearyl (meth) acrylate; (meth) acrylic acid, maleic acid, maleic anhydride, etc. Carboxyl group-containing polymerizable unsaturated monomer; aminoalkyl (meth) such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate Acrylate; acrylamide, methacrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-methylolacrylamide, N-methylol (Meth) acrylamide or derivatives thereof such as acrylamide methyl ether and N-methylolacrylamide butyl ether; 2- (methacryloyloxy) ethyltrimethylammonium chloride, 2- (methacrylo) Quaternary ammonium base-containing monomers such as (ruoxy) ethyltrimethylammonium bromide; (meth) acrylamide-alkanesulfonic acid such as 2-acrylamido-2-methylpropanesulfonic acid, sulfoalkyl such as 2-sulfoethyl (meth) acrylate (meta) ) Acrylate; Acrylic ring-containing polymerizable unsaturated monomers such as acrylonitrile, methacrylonitrile, vinyl acetate, styrene, vinyltoluene, α-methylstyrene; Polyvinyl compounds such as allyl methacrylate; γ- (meth) acryloyloxypropyltrimethoxy Hydrolyzable silyl group-containing polymerizable unsaturated monomers such as silane, γ- (meth) acryloyloxypropyltriethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, and the like. Al can be used either alone or in combination of two or more.
In the present specification, “(meth) acrylate” means acrylate or methacrylate, and “(meth) acrylic acid” means acrylic acid or methacrylic acid. “(Meth) acryloyl” means acryloyl or methacryloyl, and “(meth) acrylamide” means acrylamide or methacrylamide.

The copolymerization of the polymerizable unsaturated monomer is preferably a copolymerization by a solution polymerization method. For example, a mixture of the polymerizable unsaturated monomer and the radical polymerization initiator is dissolved or dispersed in an organic solvent. Examples of the polymerization method include heating at 80 ° C. to about 200 ° C. with stirring for about 1 to 10 hours.

In the present invention, the hydroxyl group-containing acrylic resin (A) is a specific hydroxyl group-containing acrylic resin in terms of scratch resistance, hardness, appearance, adhesion, resistance to a composition containing an ultraviolet absorber and the like of the resulting coating film. (A1) and a specific hydroxyl group-containing acrylic resin (A2) are contained.

In the coating composition of the present invention, the mixing ratio (mass ratio) of the hydroxyl group-containing acrylic resin (A1) and the hydroxyl group-containing acrylic resin (A2) is the former (A1) / the latter (A2) = 25/75 to 95. / 5, preferably 30/70 to 80/20, more preferably 40/60 to 70/30, including the scratch resistance, hardness, appearance, adhesion and UV absorber of the resulting coating film From the viewpoint of resistance to the composition to be used.

In the present invention, the content of the hydroxyl group-containing acrylic resin (A1) is the total in the main agent from the viewpoint of scratch resistance, hardness, appearance, adhesion, chemical resistance (sunscreen resistance), and the like of the obtained coating film. The amount is from 25 to 95 parts by weight, preferably from 30 to 60 parts by weight, more preferably from 40 to 50 parts by weight, based on the resin solid content.

In the present invention, the content of the hydroxyl group-containing acrylic resin (A2) is the total in the main agent from the viewpoint of scratch resistance, hardness, appearance, adhesion, chemical resistance (sunscreen resistance) and the like of the obtained coating film. The amount is 5 to 75 parts by weight, preferably 10 to 50 parts by weight, more preferably 15 to 45 parts by weight, based on the resin solids weight.

<< Hydroxyl-containing acrylic resin (A1) >>
In the present invention, the hydroxyl group-containing acrylic resin (A1) has a hydroxyl value of 70 to 200 mgKOH / g, preferably 100 to 200 mgKOH / g, more preferably 120 to 180 mgKOH / g, and a glass transition temperature of less than −30 ° C., preferably − A hydroxyl group-containing acrylic resin of less than 40 ° C., more preferably less than −50 ° C. When the hydroxyl value of the hydroxyl group-containing acrylic resin (A1) is 70 mgKOH / g or more, the adhesion, hardness and appearance of the resulting coating film are good, and when it is 200 mgKOH / g or less, the scratch resistance of the coating film is good. Therefore, it is preferable. On the other hand, if the glass transition temperature exceeds −30 ° C., the coating film may be inferior in scratch resistance.

In the present specification, the glass transition temperature Tg of the hydroxyl group-containing acrylic resin is a value calculated by the following formula.
1 / Tg (K) = W1 / T1 + W2 / T2 +... Wn / Tn
Tg (° C.) = Tg (K) -273
In the formula, W1, W2,... Wn are mass fractions of the respective monomers, and T1, T2... Tn are glass transition temperatures Tg (K) of the homopolymers of the respective monomers.
The glass transition temperature of the homopolymer of each monomer is described in POLYMERHANDBOOKFourth Edition, J. MoI. Brandrup, E .; h. Immergut, E .; A. The glass transition temperature of a monomer not described in the literature, which is a value according to Grulk (1999), was synthesized by synthesizing a homopolymer of the monomer so that the weight average molecular weight was about 50,000, and its glass transition The value when the temperature is measured by differential scanning thermal analysis is used.

Further, in this specification, the weight average molecular weight and the number average molecular weight are the retention time (retention capacity) measured using a gel permeation chromatograph (GPC), and the retention time of standard polystyrene with a known molecular weight measured under the same conditions ( It is a value obtained by converting to the molecular weight of polystyrene by (retention capacity). The columns are “TSKgel G-4000H × L”, “TSKgel G-3000H × L”, “TSKgel G-2500H × L”, “TSKgel”.
G-2000H × L "(both manufactured by Tosoh Corp., trade name), mobile phase: tetrahydrofuran, measurement temperature: 40 ° C, flow rate: 1 ml / min, detector: performed under the conditions of RI It is a thing.

The hydroxyl group-containing acrylic resin (A1) is obtained by copolymerizing a polymerizable unsaturated monomer (a1-1) having a hydroxyalkyl group having 4 to 9 carbon atoms and another polymerizable unsaturated monomer (a1-2) by a conventional method. Can be synthesized.

Examples of the polymerizable unsaturated monomer (a1-1) having a hydroxyalkyl group having 4 to 9 carbon atoms include 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. 7-hydroxyheptyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 7-methyl-8-hydroxyoctyl (meth) acrylate, 2-methyl-8-hydroxyoctyl (meth) acrylate, 9-hydroxynonyl ( (Meth) acrylate etc. are mentioned, These can be used individually or in combination of 2 or more types, respectively. Of these, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, and 6-hydroxyhexyl from the viewpoint of excellent scratch resistance, appearance, adhesion, and resistance to a composition containing an ultraviolet absorber. (Meth) acrylate is particularly preferred.

As the other polymerizable unsaturated monomer (a1-2), monomers other than the monomer (a1-1) among the monomers described in the column of the hydroxyl group-containing acrylic resin (A) can be appropriately used. Among them, from the viewpoint of obtaining a hydroxyl group-containing acrylic resin (A1) having a low Tg and obtaining a coating film excellent in resistance to a composition containing scratch resistance, hardness, appearance, adhesion, and an ultraviolet absorber, etc. The polymerizable unsaturated monomer (a1-2) particularly preferably has a polymerizable unsaturated monomer having an alkyl group having 4 to 8 carbon atoms. In the present invention, the “polymerizable unsaturated monomer having an alkyl group having 4 to 8 carbon atoms” means an alkyl group-containing polymerizable unsaturated monomer having an alkyl moiety having 4 to 8 carbon atoms. Examples of the polymerizable unsaturated monomer having an alkyl group having 4 to 8 carbon atoms include n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, n- Examples include hexyl (meth) acrylate, n-octyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. These monomers can be used alone or in combination of two or more. Of these, n-butyl (meth) acrylate and 2-ethylhexyl acrylate are particularly preferable from the viewpoint of scratch resistance, hardness, appearance, adhesion, resistance to a composition containing an ultraviolet absorber, and the like. .

The proportion of the polymerizable unsaturated monomer (a1-1) having a hydroxyalkyl group having 4 to 9 carbon atoms in the production of the hydroxyl group-containing acrylic resin (A1) is determined based on the monomer component (polymerizable unsaturated monomer (a1- Based on the total amount of 1) and (a1-2)), it is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and further preferably 20 to 40% by mass.

The proportion of other polymerizable unsaturated monomer (a1-2) used in producing the hydroxyl group-containing acrylic resin (A1) is preferably 40 to 90% by mass, based on the total amount of monomer components, and preferably 50 to 85%. More preferably, it is more preferably 60-80% by weight.

When a polymerizable unsaturated monomer having an alkyl group having 4 to 8 carbon atoms is used as the other polymerizable unsaturated monomer (a1-2), the use ratio is 10 to 80 on the basis of the total amount of the monomer components. % By mass is preferable, 15 to 70% by mass is more preferable, and 20 to 65% by mass is further preferable.

In the present invention, the hydroxyl group-containing acrylic resin (A1) preferably has a weight average molecular weight of 5,000 to 33, from the viewpoint of scratch resistance, hardness, appearance, adhesion, and resistance to a composition containing an ultraviolet absorber. 000, more preferably in the range of 8,000 to 30,000.

<< Hydroxyl-containing acrylic resin (A2) >>
In the present invention, the hydroxyl group-containing acrylic resin (A2) has a hydroxyl value of 30 to 200 mgKOH / g, preferably 50 to 180 mgKOH / g, more preferably 100 to 160 mgKOH / g, and a glass transition temperature of −30 to 75 ° C., preferably A hydroxyl group-containing acrylic resin at −20 to 50 ° C., more preferably −10 to 40 ° C.
The hydroxyl group-containing acrylic resin (A2) contains polymerizable unsaturated monomers (a2-1) to (a2-3), and the total amount of each monomer (a2-1) to (a2-3) is used as a reference.
30 to 80% by mass of methyl methacrylate (a2-1), preferably 32 to 75% by mass, more preferably 35 to 70% by mass,
The hydroxyl group-containing polymerizable unsaturated monomer (a2-2) is 10 to 35% by mass, preferably 15 to 30% by mass, more preferably 20 to 28% by mass,
And other polymerizable unsaturated monomer (a2-3) is reacted in an amount of 0 to 60% by mass, preferably 0 to 53% by mass, more preferably 2 to 45% by mass.
When the hydroxyl value of the hydroxyl group-containing acrylic resin (A2) is 30 mgKOH / g or more, the resistance to a composition containing an ultraviolet absorber is good, and when it is 200 mgKOH / g or less, the resulting coating film has good scratch resistance. This is preferable. Further, when the glass transition temperature is −30 ° C. or higher, the adhesion of the coating film is good and the resistance to the composition containing an ultraviolet absorber is good, and when it is 75 ° C. or lower, the scratch resistance of the coating film is obtained. This is preferable because the property is improved. Further, when the content of methyl methacrylate (a2-1) is 30 to 80% by mass based on the total amount of each monomer, the scratch resistance and adhesion of the coating film are improved, and an ultraviolet absorber and the like are contained. The resistance to the composition is improved.

Examples of the hydroxyl group-containing polymerizable unsaturated monomer (a2-2) include the hydroxyl group-containing polymerizable unsaturated monomer described in the column of the hydroxyl group-containing acrylic resin (A).

As other polymerizable unsaturated monomers (a2-3), among the other copolymerizable polymerizable unsaturated monomers described in the column of the hydroxyl group-containing acrylic resin (A), methyl methacrylate and hydroxyl group-containing polymerizable monomers are used. Monomers other than the saturated monomer (a2-2) can be appropriately used.

In the present invention, the hydroxyl group-containing acrylic resin (A2) preferably has a weight average molecular weight of 5,000 to 33, from the viewpoint of scratch resistance, hardness, appearance, adhesion, and resistance to a composition containing an ultraviolet absorber. 000, more preferably in the range of 8,000 to 30,000.

In the coating composition of the present invention, the hydroxyl group-containing acrylic resin (A) may include a hydroxyl group-containing acrylic resin other than the hydroxyl group-containing acrylic resin (A1) and the hydroxyl group-containing acrylic resin (A2).

<Other main ingredients>
The main agent of the present invention comprises a hydroxyl group-containing acrylic resin (A) containing the hydroxyl group-containing acrylic resin (A1) and the hydroxyl group-containing acrylic resin (A2) at a specific ratio as an essential component, and further contains a hydroxyl group as necessary. Resin components such as polyester resin (C), hydroxyl group-containing urethane resin, phenol resin, polycarbonate resin, and epoxy resin can be contained.

<< Hydroxyl-containing polyester resin (C) >>
The hydroxyl group-containing polyester resin (C) can be usually obtained by esterifying a polybasic acid and a polyhydric alcohol by a method known per se with an excess of hydroxyl groups.

A polybasic acid is a compound having two or more carboxyl groups in one molecule. For example, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, diphenylmethane-4,4 Aromatic polybasic acids such as' -dicarboxylic acid and anhydrides thereof; alicyclic dicarboxylic acids such as hexahydroisophthalic acid, hexahydroterephthalic acid, hexahydrophthalic acid and tetrahydrophthalic acid and anhydrides; adipic acid, sebacin Aliphatic polybasic acids such as acid, suberic acid, succinic acid, glutaric acid, maleic acid, chloromaleic acid, fumaric acid, dodecanedioic acid, pimelic acid, azelaic acid, itaconic acid, citraconic acid and dimer acid and their anhydrides Lower alkyl esters such as methyl esters and ethyl esters of these dicarboxylic acids; Ter; trimellitic acid, trimellitic anhydride, pyromellitic acid, pyrometic anhydride, trimesic acid, methylcyclohexentricarboxylic acid, tetrachlorohexene polybasic acid, and polybasic acids having a valence of 3 or more .

The polyhydric alcohol is a compound having two or more hydroxyl groups in one molecule. For example, ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4- Butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,5-pentanediol, , 4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2, 2,4-trimethyl-1,3-pentanediol, Dihydric alcohols such as 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, and hydroxypivalic acid neopentyl glycol ester; Polylactone diols obtained by adding lactones such as ε-caprolactone to alcohols; Ester diols such as bis (hydroxyethyl) terephthalate; Alkylene oxide adducts of bisphenol A, polyether diols such as polyethylene glycol, polypropylene glycol, polybutylene glycol Class: α-olefin epoxides such as propylene oxide and butylene oxide, Cardura E10 [manufactured by Shell Chemical Co., Ltd., trade name, glycidyl ester of synthetic hyperbranched saturated fatty acid], etc. Non-epoxy compounds; trihydric or higher alcohols such as glycerin, trimethylolpropane, trimethylolethane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, sorbitol, mannitol; Polylactone polyols obtained by adding lactones such as ε-caprolactone to higher alcohols; 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated bisphenol A, and Examples thereof include alicyclic polyhydric alcohols such as hydrogenated bisphenol F.

The introduction of a hydroxyl group can be performed, for example, by using a polyhydric alcohol having 3 or more hydroxyl groups in one molecule.

Further, at the time of the reaction of the polybasic acid and the polyhydric alcohol, a monobasic acid, an oil component (including this fatty acid) and the like may be used as necessary. Examples of the monobasic acid include benzoic acid and t-butylbenzoic acid. Examples of the oil component include castor oil, dehydrated castor oil, safflower oil, soybean oil, linseed oil, tall oil, coconut oil, and the like. These fatty acids etc. are mentioned, These can be used 1 type or in mixture of 2 or more types. Furthermore, the polyester resin may be modified with an epoxy compound such as butyl glycidyl ether, alkylphenyl glycidyl ether, or neodecanoic acid glycidyl ester, if necessary.

In the present invention, the hydroxyl group-containing polyester resin (C) has a hydroxyl value of 50 to 200 mgKOH from the viewpoint of scratch resistance, hardness, appearance, adhesion and resistance to a composition containing an ultraviolet absorber, etc. / G, preferably 60 to 150 g KOH / g, and a hydroxyl group-containing polyester resin (C1) having a weight average molecular weight of 2,000 to 20,000, preferably 2,000 to 15,000. The acid value of the hydroxyl group-containing polyester resin (C1) is preferably from 0 to 10 mgKOH / percent from the viewpoint of scratch resistance, hardness, appearance, adhesion, resistance to a composition containing an ultraviolet absorber and the like of the resulting coating film. g, more preferably 0 to 5 mg KOH / g.

Further, in the present invention, the hydroxyl group-containing polyester resin (C1) has a nurate structure from the viewpoint of scratch resistance, hardness, appearance, adhesion, resistance to a composition containing an ultraviolet absorber and the like of the obtained coating film. A hydroxyl group-containing polyester resin (C1-1) obtained by reacting a polyhydric alcohol containing a cyclic polyol compound (c1) with a polybasic acid is desirable.

Examples of the cyclic polyol compound (c1) having a nurate structure include tris (hydroxyalkyl) isocyanurate such as tris (hydroxyethyl) isocyanurate, tris (hydroxypropyl) isocyanurate and tris (hydroxybutyl) isocyanurate, the tris Ε-caprolactone modified form of (hydroxyalkyl) isocyanurate, tris (hydroxyethyl) isocyanurate, diol compound and dicarboxylic acid, and the hydroxyl group in tris (hydroxyethyl) isocyanurate and diol compound is converted to a carboxyl group in dicarboxylic acid. Tris (hydroxyethyl) isocyanurate esterified product obtained by reacting in excess, and polyisocyanate compound having nurate structure and diol A compound, a hydroxyl group in the diol compound reaction product obtained by reacting with excess state to isocyanate groups in the polyisocyanate compounds and the like having a isocyanurate structure. These can be used alone or in combination of two or more.

Of these, tris (2-hydroxyethyl) isocyanurate and ε-caprolactone-modified products of tris (2-hydroxyethyl) isocyanurate from the viewpoint of resistance of the resulting coating film to a composition containing an ultraviolet absorber or the like. Is preferred, and tris (2-hydroxyethyl) isocyanurate is more preferred.

The content ratio of the cyclic polyol compound (c1) having a nurate structure in the hydroxyl group-containing polyester resin (C1-1) is determined based on the total amount of alcohol components from the viewpoint of resistance to the composition containing an ultraviolet absorber or the like of the coating film obtained. Is preferably in the range of 1 to 75 mol%, more preferably in the range of 10 to 60 mol%.

The content of the hydroxyl group-containing polyester resin (C1) is determined based on the total solid content in the main agent from the viewpoint of scratch resistance, hardness, appearance, adhesion and resistance to a composition containing an ultraviolet absorber, etc. Is preferably 10 to 70 parts by mass, more preferably 20 to 60 parts by mass. The content of the hydroxyl group-containing polyester resin (C1-1) is the total amount in the main agent from the viewpoint of scratch resistance, hardness, appearance, adhesion, resistance to a composition containing an ultraviolet absorber and the like of the obtained coating film. The amount is preferably 10 to 50 parts by mass, more preferably 20 to 40 parts by mass based on the solid content.

(Curing agent)
The curing agent used in the present invention contains a polyisocyanate compound (B).

<Polyisocyanate compound (B)>
Examples of the polyisocyanate compound (B) include aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; biuret-type adducts of these aliphatic polyisocyanates, isocyanurate ring addition Products, allophanate type adducts, uretdione type adducts; alicyclic diisocyanates such as isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4- or -2,6-diisocyanate; Biuret type adduct of alicyclic diisocyanate, isocyanurate cycloadduct; xylylene diisocyanate, tetramethylxylylene diisocyanate , Aromatic diisocyanate compounds such as tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate, 1,4-naphthalene diisocyanate; biuret type adducts of these aromatic diisocyanates, isocyania Nurate ring adducts; hydrogenated MDI and derivatives of hydrogenated MDI; isocyanates at the hydroxyl groups of polyols such as ethylene glycol, propylene glycol, 1,4-butylene glycol, dimethylolpropionic acid, polyalkylene glycol, trimethylolpropane, hexanetriol Urethane adducts obtained by reacting polyisocyanate compounds in an excess ratio of groups; biuret type adducts and isocyanurate ring adducts of these urethanized adducts It can be mentioned. Among these, in particular, biuret-type adducts of aliphatic polyisocyanates (biuret-type polyisocyanate compounds) and allophanate-type adducts (allophanate-type polyisocyanate compounds) are used to obtain scratch resistance, hardness, appearance, It can be preferably used from the viewpoints of adhesion and resistance to a composition containing an ultraviolet absorber and the like.

The amount of the polyisocyanate compound (B) used is usually such that the isocyanate group (NCO) contained therein is an equivalent ratio of NCO / OH to the hydroxyl group (OH) in the main agent, and is 0.5 to It is appropriate to select it within a range of 2.0, preferably 0.8 to 1.5.

In the coating composition of the present invention, if necessary, a coating used in the field of ordinary coatings such as an organic solvent, a curing catalyst, a pigment, a pigment dispersant, a leveling agent, an ultraviolet absorber, a light stabilizer, and a plasticizer. Additives can be combined in the main agent and / or curing agent in an appropriate combination.

The organic solvent is not particularly limited, and for example, usual paint solvents such as hydrocarbon, ester, ether, alcohol, and ketone can be used.

Examples of the curing catalyst include tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, and dioctyl. Organic metals such as tin oxide, dibutyltin fatty acid salt, lead 2-ethylhexanoate, zinc octylate, zinc naphthenate, fatty acid zinc, cobalt naphthenate, calcium octylate, copper naphthenate, tetra (2-ethylhexyl) titanate A compound is mentioned, These can be used 1 type or in mixture of 2 or more types. These may be used in combination with known urethane curing catalysts such as tertiary amines and phosphoric acid compounds, if necessary. When the coating composition of the present invention contains a curing catalyst, the amount of the curing catalyst used is usually 0.001 to 2 parts by mass, preferably 0.01 to 100 parts by mass of the resin solid content in the coating composition. The range of ~ 1 part by mass is appropriate.

Examples of the pigment include titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chromium yellow, chromium oxide, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, selenium pigment, Color pigments such as perylene pigments; body pigments such as talc, clay, kaolin, barita, barium sulfate, barium carbonate, calcium carbonate, alumina white; metallic pigments such as aluminum powder, mica powder, mica powder coated with titanium oxide, etc. Can be mentioned. These can be used alone or in combination of two or more.

When the paint composition of the present invention is used as a clear paint and contains a pigment, the amount of the pigment is preferably an amount that does not hinder the transparency of the resulting coating film, for example, Usually, it is preferably in the range of 0.1 to 20 parts by weight, more preferably in the range of 0.3 to 10 parts by weight, based on 100 parts by weight of the solid content in the coating composition. More preferably, it is in the range of 5 to 5 parts by mass.

In the case where the coating composition of the present invention is used as a colored coating and contains a pigment, the blending amount of the pigment is usually 1 to 200 based on 100 parts by mass of the solid content in the coating composition. It is preferably in the range of parts by mass, more preferably in the range of 2 to 100 parts by mass, and still more preferably in the range of 5 to 50 parts by mass.

As the ultraviolet absorber, conventionally known ones can be used, and examples thereof include ultraviolet absorbers such as benzotriazole absorbers, triazine absorbers, salicylic acid derivative absorbers, and benzophenone absorbers. These can be used alone or in combination of two or more.

When the coating composition of the present invention contains an ultraviolet absorber, the blending amount of the ultraviolet absorber is in the range of 0.1 to 10 parts by mass based on 100 parts by mass of the solid content in the coating composition. It is preferably within the range of 0.2 to 5 parts by mass, and more preferably within the range of 0.3 to 2 parts by mass.

As the light stabilizer, conventionally known light stabilizers can be used, and examples thereof include hindered amine light stabilizers.

When the coating composition of the present invention contains a light stabilizer, the blending amount of the light stabilizer is in the range of 0.1 to 10 parts by mass based on 100 parts by mass of the solid content in the coating composition. It is preferably within the range of 0.2 to 5 parts by mass, and more preferably within the range of 0.3 to 2 parts by mass.

From the viewpoint of storage stability, the coating composition of the present invention is preferably used as a two-pack type coating composed of the main agent and the curing agent, and both are mixed immediately before use.

In the present invention, a coated article can be obtained by painting the coating composition on the surface of a plastic substrate. The plastic substrate is not particularly limited. For example, a polyolefin-based resin represented by polyethylene, polypropylene, etc .; polyethylene terephthalate resin, polybutylene terephthalate (PBT) resin, polycarbonate (PC) resin, polycarbonate-polybutylene terephthalate Thermoplastic polyester resins such as (PC / PBT) resin; Styrenic resins such as acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene-acrylate (ASA) resin; Other polymethyl methacrylate resin, acrylic Resin, vinylidene chloride, polyamide resin, polyphenylene ether resin, polyoxymethylene resin, polyurethane resin, epoxy resin, etc. It can be mentioned materials surface, such as a hybrid resin and fiber reinforced plastic (Fiber-Reinforced Plastics). These material surfaces may be subjected to a degreasing treatment or a surface treatment as needed. Furthermore, after forming an undercoat film on the plastic substrate surface, the coating composition of the present invention may be applied.

The method for applying the coating composition of the present invention is not particularly limited. For example, it can be applied by air spray, airless spray, rotary atomizing coater, dip coating, brush or the like.

The coating film of the coating composition of the present invention can usually have a cured film thickness of usually 3 to 100 μm, preferably 3 to 50 μm.

In the method for forming a coating film of the coating composition of the present invention, the heating conditions are not particularly limited, but it can be carried out by holding at 50 to 100 ° C., preferably 50 to 90 ° C. for 10 to 90 minutes. When the plastic material is deformed by heat, the heating condition is preferably maintained at 50 to 80 ° C. for 10 to 90 minutes, for example, when an ABS resin is used.

The coating film obtained by the coating composition of the present invention has a glass transition temperature of 20 in terms of scratch resistance, hardness, appearance, adhesion and resistance to a composition containing an ultraviolet absorber and the like. It is suitable that the temperature is -60 ° C, preferably 30-55 ° C, more preferably 35-50 ° C. The glass transition temperature is obtained by using a dynamic viscoelasticity measuring apparatus as a measurement sample, and forming a 25 μm-thick coating film that has been heat-cured at 80 ° C. for 30 minutes into a strip-shaped free film (0.5 cm × 2 cm). This is the temperature at which the value of tan δ shows a maximum value when the tan δ value is measured under conditions of a temperature range of 20 to 200 ° C. and a frequency of 11 Hz using a prepared temperature rate of 3 ° C./min. . As a dynamic viscoelasticity measuring apparatus, FT Rheospectra DVE-V4 (trade name, manufactured by Rheology) can be used.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to only these examples. “Part” and “%” represent “part by mass” and “% by mass”, respectively. Moreover, the film thickness of a coating film is based on a cured coating film.

[Production of hydroxyl group-containing acrylic resin (A1)]
Production Example 1
A reaction vessel equipped with a stirrer, thermometer, reflux condenser, thermostat and dropping pump was charged with 50 parts of butyl acetate and heated to 115 ° C. while blowing nitrogen gas. Thereafter, while maintaining the reaction system at 115 ° C. ± 3 ° C., with stirring, 25 parts of 4-hydroxybutyl acrylate, 10 parts of 2-hydroxyethyl acrylate, 25 parts of n-butyl methacrylate, 40 parts of 2-ethylhexyl acrylate, And a mixture of 2.0 parts of 2,2′-azobisisobutyronitrile and a polymerization initiator are dropped into the reaction vessel at a constant rate over a period of 3 hours using a dropping pump. Aging for 1 hour at temperature. Thereafter, a mixture of 0.5 part of 2,2′-azobisisobutyronitrile and 17 parts of butyl acetate was added dropwise to the reaction vessel over 1 hour. After completion of the addition, the mixture was aged for 1 hour to complete the reaction.
The obtained hydroxyl group-containing acrylic resin (A1-1) solution was a uniform transparent solution having a solid content of 60%. The weight average molecular weight of the acrylic resin was about 20,000, the hydroxyl value was 146 mgKOH / g, and the glass transition temperature was −41 ° C.

Production Examples 2 to 11
In the above Production Example 1, the same operations as in Production Example 1 were performed except that the monomer mixture had the composition shown in Table 1, and the hydroxyl group-containing acrylic resins (A1-2) to (A1-11) having a solid content of 60% were obtained. ) A solution was obtained. Table 1 shows the weight average molecular weight, hydroxyl value, and glass transition temperature of each hydroxyl group-containing acrylic resin obtained.

[Production of hydroxyl group-containing acrylic resin (A2)]
Production Example 12
A reaction vessel equipped with a stirrer, thermometer, reflux condenser, thermostat and dropping pump was charged with 60 parts of butyl acetate and stirred at 125 ° C. ± 3 ° C. while blowing nitrogen gas, and 45 parts of methyl methacrylate were added therein. , A mixture of 25 parts of 2-hydroxyethyl acrylate, 20 parts of n-butyl acrylate, 10 parts of lauryl methacrylate and 2.0 parts of 2,2′-azobisisobutyronitrile was added dropwise at a constant rate over 3 hours, Further, aging was performed at the same temperature for 1 hour. Thereafter, a mixture of 0.5 part of 2,2′-azobisisobutyronitrile and 21 parts of butyl acetate was added dropwise to the reaction vessel over 1 hour, and after completion of the addition, the mixture was aged for 1 hour to complete the reaction.
The obtained hydroxyl group-containing acrylic resin (A2-1) solution was a uniform transparent solution having a solid content of 55%. The weight average molecular weight of the acrylic resin was about 21,000, the hydroxyl value was 121 mgKOH / g, and the glass transition temperature was −7 ° C.

Production Examples 13 to 27
In the above Production Example 12, the same operation as in Production Example 12 was carried out except that the mixture of monomers was changed to the composition shown in Table 2, and the hydroxyl group-containing acrylic resins (A2-2) to (A2-16) having a solid content of 60% were obtained. ) A solution was obtained. Table 2 shows the weight average molecular weight, hydroxyl value, and glass transition temperature of each hydroxyl group-containing acrylic resin obtained.

[Production of hydroxyl group-containing polyester resin]
Production Example 28
A reaction vessel equipped with a stirrer, thermometer, rectification column and water separator is charged with 136 parts of hexahydrophthalic anhydride, 83 parts of 1,6-hexanediol and 78 parts of tris (2-hydroxyethyl) isocyanurate. The temperature was raised to 160 ° C. in a nitrogen atmosphere.

Thereafter, the temperature was raised to 220 ° C. over 3 hours, and xylene was added to carry out the reaction under reflux while distilling off water. After cooling when the desired acid value was reached, it was diluted with butyl acetate to obtain a polyester resin (C-1) solution having a solid content of 50%. This polyester resin (C-1) had a number average molecular weight of 2,200 and a hydroxyl value of 113 mgKOH / g.

Production Examples 29-31
In the above Production Example 28, the same procedure as in Production Example 28 was carried out except that the mixture of the monomer and the polymerization initiator was changed to the composition shown in Table 3, and a hydroxyl-containing polyester resin (C-2) having a solid content of 50% was obtained. (C-4) A solution was obtained. Table 3 shows the number average molecular weight and hydroxyl value of each obtained hydroxyl group-containing polyester resin.

[Manufacture of coating composition]
Examples and Comparative Examples Each component was uniformly mixed so as to have the composition shown in Table 4. Next, a diluting solvent was added to the resulting mixture, and a Ford Cup No. A coating composition having a viscosity according to 4 of 25 seconds was obtained.

Components (A) and (C) were mixed and stirred so as to have the blending composition shown in Table 4 to prepare each main agent having a solid content of about 40%. The curing agent of component (B) was added to this main agent so as to have the composition shown in Table 4, and mixed uniformly. Next, a diluting solvent was added to the resulting mixture, and a Ford Cup No. A coating composition having a viscosity according to 4 of 25 seconds was obtained.

Table 4 shows the solid content, and (B-1) to (B-3) in Table 4 are as follows.
(B-1): Duranate 24A-90E, trade name, manufactured by Asahi Kasei Chemicals Corporation, hexamethylene diisocyanate biuret type, solid content 90%, isocyanate group content 21.2%
(B-2) XP2580: trade name, manufactured by Bayer, allophanate type of hexamethylene diisocyanate, solid content 100%, isocyanate group content 19.5%
(B-3) Sumidur N3300: trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd., hexamethylene diisocyanate nurate, solid content 100%, isocyanate group content 21.8%

[Preparation of test coated plate]
Each of the coating compositions prepared as described above is applied to an ABS plate (black, degreased) by air spray coating so that the cured film thickness is about 25 μm, and cured by heating at 80 ° C. for 30 minutes for each test. A coated plate was obtained.

Each obtained test coated plate was subjected to the following performance test. The results are also shown in Table 4.

[Coating performance test]
Scratch resistance: The test coated plate obtained as described above was set in a Gakushin type friction fastness tester “RT-200” (trade name, manufactured by Daiei Chemical Seiki Seisakusho Co., Ltd.). No. A 2000 sandpaper was affixed with double-sided tape, a 200 g weight was placed on the friction element, and the coating film was scratched by polishing twice back and forth. After standing at 25 ° C. for 24 hours, the L15 ° value of the coating film was measured and evaluated based on the following criteria from the difference (ΔL15 °) from the L15 ° value of the coating film before scratching.

The measurement of the L15 ° value is performed using a variable angle color difference meter “MA68II” (trade name, manufactured by X-Rite Co., Ltd.) with the L in the light receiving angle direction of 15 degrees with respect to the direction in which light is incident in the direction perpendicular to the scratch. The value (this is referred to as L15 ° value) was read and the difference ΔL15 ° before and after the test was calculated. The case where ΔL15 ° exceeds 30 is rejected.

Pencil hardness: Implemented according to JIS K 5600-5-4 (1999). The pencil lead was applied at an angle of about 45 ° with respect to the coating surface of each test coating plate, and the pencil was moved forward at a uniform speed by about 10 mm while pressing firmly against the coating surface so as not to break the core. This operation was repeated 5 times at different locations, and the hardness symbol of the hardest pencil that did not leave a pencil lead mark on the coating film was defined as pencil hardness.

Adhesiveness: Cut lines were made with a cutter so as to reach the substrate on the coating film surface of each test coating plate, and 100 squares having a size of 2 mm × 2 mm were made. Subsequently, a cellophane pressure-sensitive adhesive tape and a cloth pressure-sensitive adhesive tape were adhered to the coating surface, and the number of cells remaining after the film was rapidly peeled off at 20 ° C. was evaluated according to the following criteria. .

A: The number of cells remaining when the cellophane adhesive tape was peeled off was 100, and the number of cells remaining when the cloth adhesive tape was peeled off was 100. ○: The number of squares in which the coating film remains when the cellophane adhesive tape is peeled off, and the square in which the coating film remains when the cloth adhesive tape is peeled off The number is 99 or less. X: The number of cells remaining when the cellophane adhesive tape is peeled is 99 or less, and the film remains when the cloth adhesive tape is peeled off. The number of squares is 99 or less

Resistance to a composition containing an ultraviolet absorber, etc .: 0.5 g / 100 cm ² of cosmetics per unit coating area on the coating surface of each test coating plate (Givenchy DW UV Shield, trade name, manufactured by Parfum Givenchy), SPF50 PA ++ ), Left at 55 ° C. for 4 hours, cooled to room temperature, wiped off the cosmetics on the surface, and evaluated the appearance of the coating film, pencil hardness and adhesion. The pencil hardness is measured by the same method as described above, and the pencil hardness symbol that is within two ranks down from the hardness symbol obtained in the above-mentioned “pencil hardness:” section is regarded as acceptable. The evaluation of adhesion was performed in the same manner as the above method. The appearance of the coating film was evaluated according to the following criteria.

○: No abnormality ×: Smudge, discoloration, marks, peeling occurred

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on September 10, 2013 (Japanese Patent Application No. 2013-187105), the contents of which are incorporated herein by reference.

Claims

A coating composition comprising a main agent containing a hydroxyl group-containing acrylic resin (A) and a curing agent containing a polyisocyanate compound (B),
The hydroxyl group-containing acrylic resin (A) has a hydroxyl value of 70 to 200 mgKOH / g and a glass transition temperature of less than −30 ° C. of 25 to 95 parts by mass based on the resin solid mass in the main agent, and 5 to 75 parts by mass of a hydroxyl group-containing acrylic resin (A2) having a hydroxyl value of 30 to 200 mg KOH / g and a glass transition temperature of -30 to 75 ° C.
And,
The hydroxyl group-containing acrylic resin (A2) is based on the total amount of the polymerizable unsaturated monomers (a2-1) to (a2-3).
30-80% by mass of methyl methacrylate (a2-1),
Hydroxyl-containing polymerizable unsaturated monomer (a2-2) 10 to 35% by mass, and other polymerizable unsaturated monomer (a2-3) 0 to 60% by mass
The coating composition which is a hydroxyl-containing acrylic resin obtained by making this react.
The hydroxyl group-containing acrylic resin (A1) is based on the total amount of the polymerizable unsaturated monomers (a1-1) and (a1-2).
10 to 60% by mass of polymerizable unsaturated monomer (a1-1) having a hydroxyalkyl group having 4 to 9 carbon atoms and 40 to 90% by mass of other polymerizable unsaturated monomer (a1-2)
The coating composition according to claim 1, wherein the coating composition is a hydroxyl group-containing acrylic resin obtained by reacting.
The coating composition according to claim 1 or 2, wherein the polyisocyanate compound (B) is at least one selected from the group consisting of a biuret type polyisocyanate compound and an allophanate type polyisocyanate compound.
The coating composition according to any one of claims 1 to 3, wherein the main agent further contains a hydroxyl group-containing polyester resin (C).
5. A method for coating the plastic substrate surface with the coating composition according to any one of claims 1 to 4.
A coated article obtained by coating the plastic substrate surface with the coating composition according to any one of claims 1 to 4.