阅读说明：本技术 涂料组合物 (Coating composition ) 是由 中林拓也 上田拓弥 于 2018-12-20 设计创作，主要内容包括：本发明涉及一种涂料组合物,其包含(A)粘合剂成分和(B)流变调节剂,所述粘合剂成分(A)包含：含烷氧基甲硅烷基的丙烯酸树脂(A1)；并且所述流变调节剂(B)包含：(b1)多异氰酸酯化合物,(b2)数均分子量为300以下的伯单胺,以及(b3)数均分子量大于300而小于6000的聚醚胺的反应产物。(The present invention relates to a coating composition comprising (a) a binder component comprising: an alkoxysilyl group-containing acrylic resin (a 1); and the rheology modifier (B) comprises: (b1) a polyisocyanate compound, (b2) a primary monoamine having a number average molecular weight of 300 or less, and (b3) a polyetheramine having a number average molecular weight of more than 300 and less than 6000.)

1. A coating composition comprising (A) a binder component and (B) a rheology modifier,

the adhesive component (a) comprises: an alkoxysilyl group-containing acrylic resin (a 1);

and, the rheology modifier (B) comprises: (b1) a polyisocyanate compound, (b2) a primary monoamine having a number average molecular weight of 300 or less, and (b3) a polyetheramine having a number average molecular weight of more than 300 and less than 6000.

2. The coating composition according to claim 1, wherein the alkoxysilyl group-containing acrylic resin (a1) is a hydroxyl group-and alkoxysilyl group-containing acrylic resin (a 1').

3. A coating composition according to claim 1 or 2, wherein the binder component (a) further comprises a cross-linking agent (a 3).

4. The coating composition of claim 3, wherein the crosslinker (A3) comprises: at least one selected from the group consisting of amino resins, polyisocyanate compounds and blocked polyisocyanate compounds.

5. The coating composition of claim 3, wherein the crosslinker (A3) comprises: a polyisocyanate compound.

6. A coating composition according to any one of claims 1 to 5 wherein the primary monoamine (b2) having a number average molecular weight of 300 or less comprises: primary monoamines containing a benzene ring.

7. The coating composition of any one of claims 1 to 6, wherein the polyetheramine (b3) having a number average molecular weight of greater than 300 and less than 6000 is a diamine.

8. The coating composition according to any one of claims 1 to 7, wherein the compounding ratio of the polyisocyanate compound (B1), the primary monoamine (B2) having a number average molecular weight of 300 or less, and the polyetheramine (B3) having a number average molecular weight of more than 300 and less than 6000 in the rheology modifier (B) is: the amount of the polyisocyanate compound (b1) is in the range of 30 to 60% by mass, the amount of the primary monoamine (b2) having a number average molecular weight of 300 or less is in the range of 35 to 65% by mass, and the amount of the polyetheramine (b3) having a number average molecular weight of more than 300 and less than 6000 is in the range of 0.5 to 15% by mass, based on the total amount of the components (b1) to (b 3).

9. The coating composition according to any one of claims 1 to 8, wherein the content of the rheology modifier (B) is in the range of 0.1 to 3 parts by mass with respect to 100 parts by mass of the solid content of the binder component (A).

Technical Field

The present invention relates to a coating composition.

Background

In order to impart excellent appearance and properties to a substrate, it is common to form a coating film on the substrate by applying a coating composition to the substrate to form a wet coating film and by curing the wet coating film.

In such coating compositions, studies have been made to improve the scratch resistance of the coating film by using an acryl silane (シランアクリル, acryl silane). For example, patent document 1 discloses a curable composition containing an alkoxysilyl group-containing acrylic polymer having a silicon equivalent (silicon equivalent) of 700 or less, an acrylic resin having a glass transition temperature of 30 ℃ or less, and a curing catalyst. However, in the coating composition using the acryl silane, the transparency, water resistance and finished appearance (smoothness, etc.) of the obtained coating film are sometimes insufficient.

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coating composition capable of forming a coating film having excellent scratch resistance, transparency, water resistance, and finished appearance.

Technical scheme for solving problems

The present inventors have conducted extensive studies in order to achieve the above object, and as a result, found that the above technical problems can be achieved by a coating composition comprising (a) a binder component and (B) a rheology modifier, wherein the binder component (a) comprises: an alkoxysilyl group-containing acrylic resin (a 1); and, the rheology modifier (B) comprises: (b1) a polyisocyanate compound, (b2) a primary monoamine having a number average molecular weight of 300 or less, and (b3) a polyetheramine having a number average molecular weight of more than 300 and less than 6000.

Specifically, the present invention includes the following embodiments.

A coating composition comprising (a) a binder component and (B) a rheology modifier, the binder component (a) comprising: an alkoxysilyl group-containing acrylic resin (a 1); and the rheology modifier (B) comprises: (b1) a polyisocyanate compound, (b2) a primary monoamine having a number average molecular weight of 300 or less, and (b3) a polyetheramine having a number average molecular weight of more than 300 and less than 6000.

Item 2. the coating composition of item 1, wherein the alkoxysilyl group-containing acrylic resin (A1) is an alkoxysilyl group-and hydroxyl group-containing acrylic resin (A1').

Item 3. the coating composition of item 1 or 2, wherein the binder component (a) further comprises a crosslinker (a 3).

The coating composition of item 3, wherein the crosslinker (A3) comprises: at least one selected from the group consisting of amino resins, polyisocyanate compounds and blocked polyisocyanate compounds.

The coating composition of item 3, wherein the crosslinker (A3) comprises: a polyisocyanate compound.

The coating composition of any of items 1 to 5, wherein the primary monoamine (b2) having a number average molecular weight of 300 or less comprises: primary monoamines containing a benzene ring.

Item 7 the coating composition of any one of items 1 to 6, wherein the polyetheramine (b3) having a number average molecular weight of more than 300 and less than 6000 is a diamine.

Item 8. the coating composition according to any one of items 1 to 7, wherein a compounding ratio of the polyisocyanate compound (B1), the primary monoamine (B2) having a number average molecular weight of 300 or less, and the polyetheramine (B3) having a number average molecular weight of more than 300 and less than 6000 in the rheology modifier (B) is: the amount of the polyisocyanate compound (b1) is in the range of 30 to 60% by mass, the amount of the primary monoamine (b2) having a number average molecular weight of 300 or less is in the range of 35 to 65% by mass, and the amount of the polyetheramine (b3) having a number average molecular weight of more than 300 and less than 6000 is in the range of 0.5 to 15% by mass, based on the total amount of the components (b1) to (b 3).

The coating composition according to any one of items 1 to 8, wherein the content of the rheology modifier (B) is in the range of 0.1 to 3 parts by mass based on 100 parts by mass of the solid content of the binder component (A).

Advantageous effects of the invention

The coating composition of the present invention is a coating composition comprising (a) a binder component and (B) a rheology modifier, wherein the binder component (a) comprises: an alkoxysilyl group-containing acrylic resin (a 1); and, the rheology modifier (B) comprises: (b1) a polyisocyanate compound, (b2) a primary monoamine having a number average molecular weight of 300 or less, and (b3) a polyetheramine having a number average molecular weight of more than 300 and less than 6000. Therefore, the present invention achieves the effect of forming a coating film having excellent scratch resistance, transparency, water resistance, and finished appearance.

Detailed Description

The coating composition of the present invention is described in more detail below.

The coating composition of the present invention (hereinafter sometimes simply referred to as "coating of the present invention") comprises (a) a binder component and (B) a rheology modifier, wherein the binder component (a) comprises: an alkoxysilyl group-containing acrylic resin (a 1); and the rheology modifier (B) comprises: (b1) a polyisocyanate compound, (b2) a primary monoamine having a number average molecular weight of 300 or less, and (b3) a polyetheramine having a number average molecular weight of more than 300 and less than 6000.

Adhesive component (A)

The binder component (a) itself has film-forming properties, may be non-crosslinking type or crosslinking type, and is particularly preferably crosslinking type. As binder component (A), it is possible to use known film-forming resins which are used as binder components in coatings. The film-forming resin may be used alone or in combination of two or more.

The coating composition of the present invention comprises an alkoxysilyl group-containing acrylic resin (a1) as at least a part of the binder component (a).

Acrylic resin containing alkoxysilyl group (A1)

The alkoxysilyl group-containing acrylic resin (a1) is an acrylic resin containing at least one alkoxysilyl group in one molecule.

Examples of the alkoxy moiety of the alkoxysilyl group in the alkoxysilyl group-containing acrylic resin (A1) include alkoxy moieties having about 1 to 6 carbon atoms, and preferably 1 to 3 carbon atoms, such as methoxy group, ethoxy group, and propoxy group. The alkoxy moiety is more preferably a methoxy group and an ethoxy group, and still more preferably a methoxy group, from the viewpoint of scratch resistance of the obtained coating film.

Examples of the alkoxysilyl group include a trialkoxysilyl group, a dialkoxysilyl group, and a monoalkoxysilyl group. The alkoxysilyl group is preferably a trialkoxysilyl group from the viewpoint of scratch resistance of the obtained coating film.

When the alkoxysilyl group is a dialkoxysilyl group or a monoalkoxysilyl group, as a group bonded to a silicon atom other than the alkoxy group, an alkyl group having about 1 to 6 carbon atoms, and preferably about 1 to 3 carbon atoms (e.g., methyl, ethyl, propyl) can be used.

The alkoxysilyl group-containing acrylic resin (a1) can be obtained by copolymerizing an alkoxysilyl group-containing polymerizable unsaturated monomer with other polymerizable unsaturated monomers (polymerizable unsaturated monomers other than the alkoxysilyl group-containing polymerizable unsaturated monomer).

The polymerizable unsaturated monomer containing an alkoxysilyl group is a compound having 1 or more alkoxysilyl groups and 1 or more polymerizable unsaturated bonds in one molecule. Examples of the alkoxysilyl group-containing polymerizable unsaturated monomer include: vinyltrimethoxysilane, vinyltriethoxysilane, acryloxyethyltrimethoxysilane, methacryloxyethyltrimethoxysilane, acryloxypropyltrimethoxysilane, methacryloxypropyltrimethylsilane, acryloxypropyltriethoxysilane, methacryloxypropyltriethoxysilane, vinyltris (. beta. -methoxyethoxy) silane, and the like.

From the viewpoint of scratch resistance of the obtained coating film, as the alkoxysilyl group-containing polymerizable unsaturated monomer, vinyltrimethoxysilane, γ -acryloyloxypropyltrimethoxysilane, and γ -methacryloyloxypropyltrimethoxysilane are preferable, and γ -methacryloyloxypropyltrimethoxysilane is more preferable.

Commercially available products can be used as the alkoxysilyl group-containing polymerizable unsaturated monomer. Examples include: KBM-1003, KBE-1003, KBM-502, KBM-503, KBE-502, KBE-503, KBM-5103, KBM-5803 (each manufactured by Shin-Etsu chemical Co., Ltd.), Y-9936, A-174 (manufactured by Momentive Performance Materials Japan GK), OFS-6030 and Z-6033 (manufactured by Toray Dow Corning).

The alkoxysilyl group-containing polymerizable unsaturated monomer may be used alone or in combination of two or more.

As other polymerizable unsaturated monomers copolymerizable with the alkoxysilyl group-containing polymerizable unsaturated monomer, the following monomers (1) to (7) can be used. These polymerizable unsaturated monomers may be used alone or in combination of two or more.

(1) Polymerizable unsaturated monomer containing hydroxyl group

The hydroxyl group-containing polymerizable unsaturated monomer is a compound containing one or more hydroxyl groups and one or more polymerizable unsaturated bonds in one molecule. Examples of the hydroxyl group-containing polymerizable unsaturated monomers include: monoesterification products of glycols having 2 to 8 carbon atoms (e.g., 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate) with (meth) acrylic acid; a caprolactone-modified product of the mono-esterification product of such a diol having 2 to 8 carbon atoms with (meth) acrylic acid; adducts of (meth) acrylic acid with epoxy group-containing compounds (for example, Cardura E10P (manufactured by Hexion Specialty Chemicals Inc., trade name, glycidyl ester of synthetic highly branched saturated fatty acid (glycidyl neodecanoate)); N-methylol (meth) acrylamide; allyl alcohol, (meth) acrylic acid esters having a polyoxyethylene chain whose molecular terminal is a hydroxyl group; and the like.

(2) Polymerizable unsaturated monomers containing acid groups

The polymerizable unsaturated monomer containing an acid group is a compound having one or more acid groups and one or more polymerizable unsaturated bonds in one molecule. Examples of monomers include: carboxyl group-containing monomers such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, and maleic anhydride; sulfonic acid-containing monomers such as vinylsulfonic acid and 2-methyl-2-propenoic acid-2-sulfoethyl ester; and acid phosphate monomers such as 2- (meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxypropyl acid phosphate, 2- (meth) acryloyloxy-3-chloropropyl phosphate, and 2-methacryloyloxyethylphenyl phosphate (2-methacryloyloxypropylphenyl phosphoric acid). These monomers may be used alone or in combination of two or more.

By using a carboxyl group-containing monomer as at least a part of the other polymerizable unsaturated monomer, a carboxyl group-and alkoxysilyl group-containing acrylic resin can be obtained.

When a polymerizable unsaturated monomer having an acid group is used, it is preferable to use the monomer in an amount such that the acid value of the alkoxysilyl group-containing acrylic resin (A1) is from 0.5 to 15mg KOH/g, more preferably from 1 to 10mg KOH/g.

(3) Esterification products of acrylic acid or (meth) acrylic acid with monohydric alcohols having 1 to 20 carbon atoms

Specific examples include: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isomyristyl (meth) acrylate, octadecyl (meth) acrylate, isostearyl acrylate (trade name, Osaka Organic Chemical Industry, manufactured by ltd., (lauryl (meth) acrylate), tridecyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and the like.

(4) Aromatic vinyl monomer

Specific examples include styrene, alpha-methylstyrene, vinyltoluene, and the like.

When an aromatic vinyl monomer is used as a constituent component, the glass transition temperature of the resulting resin is increased, and a hydrophobic coating film having a high refractive index can be obtained. By improving the gloss of the coating film, excellent finished appearance can be obtained.

When an aromatic vinyl monomer is used as the constituent component, the proportion thereof is preferably 3 to 50% by mass, more preferably 5 to 40% by mass, based on the total amount of the monomer components.

(5) Polymerizable unsaturated monomers containing glycidyl groups

The glycidyl group-containing polymerizable unsaturated monomer is a compound having one or more glycidyl groups and one or more polymerizable unsaturated bonds in one molecule. Specific examples include glycidyl acrylate, glycidyl (meth) acrylate, and the like.

By using a glycidyl group-containing polymerizable unsaturated monomer as at least a part of other polymerizable unsaturated monomers, an epoxy and alkoxysilyl group-containing acrylic resin can be obtained.

(6) Compounds containing nitrogen and polymerizable unsaturated bonds

Examples include: (meth) acrylamide, N-dimethyl (meth) acrylamide, N- [3- (dimethylamino) propyl ] (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, ethyl N, N-dimethylamino (meth) acrylate, vinylpyridine, vinylimidazole, acrylonitrile, methacrylonitrile, and the like.

(7) Other vinyl compounds

Examples include: vinyl acetate, vinyl propionate, vinyl chloride, vinyl versatate, and the like. Examples of vinyl versatate include commercially available products VEOVA 9 and VEOVA 10 (trade name, manufactured by Mitsubishi Chemical Corporation), and the like.

As the other polymerizable unsaturated monomer, those listed in the above-mentioned (1) to (7) may be used alone, or two or more kinds may be used in combination.

The term "polymerizable unsaturated monomer" as used herein refers to a monomer having one or more (e.g., 1 to 4) polymerizable unsaturated groups. Polymerizable unsaturated groups are unsaturated groups which can undergo free radical polymerization. Examples of polymerizable unsaturated groups include: vinyl, (meth) acryloyl, (meth) acrylamido, vinyl ether, allyl, propenyl, isopropenyl, maleimido, and the like.

The term "(meth) acrylate" as used herein refers to either acrylate or methacrylate. The term "(meth) acrylic" refers to either acrylic or methacrylic. The term "(meth) acryl" refers to acryl or methacryl. The term "(meth) acrylamide" refers to acrylamide or methacrylamide.

In the production of the alkoxysilyl group-containing acrylic resin (a1), the content of the alkoxysilyl group-containing polymerizable unsaturated monomer is preferably in the range of 3 to 60 mass%, preferably 10 to 50 mass%, more preferably 20 to 40 mass%, based on the total amount of the comonomer components, from the viewpoint of the finished appearance and scratch resistance of the obtained coating film.

The weight average molecular weight of the alkoxysilyl group-containing acrylic resin (a1) is preferably 2000 to 50000, more preferably 3000 to 30000, and still more preferably 4000 to 20000, from the viewpoint of the finished appearance and curability of the coating film.

In the present specification, the average molecular weight refers to a value calculated by a chromatogram measured by gel permeation chromatography based on the molecular weight of standard polystyrene. Here, HLC8120GPC (manufactured by TosohCorporation) was used for the gel permeation chromatograph. The column was measured using TSKgel G-4000HXL, TSKgel G-3000HXL, TSKgel G-2500HXL and TSKgel G-2000HXL (trade name, each manufactured by Tosoh Corporation) four columns under conditions that the mobile phase was tetrahydrofuran, the measurement temperature was 40 ℃, the flow rate was 1 cc/min and the detector was RI.

The glass transition temperature of the alkoxysilyl group-containing acrylic resin (A1) is preferably in the range of-50 to 60 ℃, more preferably-15 to 45 ℃, and still more preferably 0 to 40 ℃ from the viewpoint of the hardness of the coating film and the appearance of the finished product.

In the present specification, the glass transition temperature (. degree. C.) of the acrylic resin is calculated using the following formula.

1/Tg(K)＝(W1/T1)+(W2/T2)+…… (1)

Tg(℃)＝Tg(K)–273 (2)

In each formula, Wl, W2, … … represent the mass fraction of the monomer used for copolymerization, and T1, T2, … … represent the tg (k) of the homopolymer of each monomer.

T1, T2, … … are values disclosed in Polymer Hand Book, second edition, eds.J.Brantup and E.H.Immergut III-139-179. When the homopolymer Tg of the monomer is unclear, the glass transition temperature (. degree. C.) refers to the static glass transition temperature. For example, a sample is put into a measuring cup and vacuum suction is performed to completely remove the solvent, and then a change in heat at a temperature range of-20 to +200 ℃ at a temperature rising rate of 3 ℃/minute is measured using a differential scanning calorimeter DSC-220U (manufactured by Seiko Instruments Inc.). The initial change point of the baseline on the low temperature side is considered as the static glass transition temperature.

The method for obtaining the alkoxysilyl group-containing acrylic resin (a1) by copolymerizing the monomer mixture is not particularly limited, and a known copolymerization method can be used. Among them, it is preferable to use a solution polymerization method in which polymerization is carried out in an organic solvent in the presence of a polymerization initiator.

Examples of the organic solvent used in the solution polymerization method include: toluene, xylene, Swasol 1000 (trade name, Cosmo Oil co., ltd., high boiling point petroleum-based solvent), and similar aromatic-based solvents; ester solvents such as ethyl acetate, butyl acetate, propyl propionate, butyl propionate, 1-methoxy-2-propyl acetate, 2-ethoxyethyl propionate, butyl 3-methoxyacetate, ethylene glycol ethyl ether acetate, and propylene glycol methyl ether acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone; alcohol solvents such as isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and 2-ethylhexanol; and so on.

These organic solvents may be used alone or in combination of two or more. From the viewpoint of solubility of the acrylic resin, ester-based solvents and ketone-based solvents are preferable. In addition, aromatic solvents may also be used in appropriate combination.

Examples of the polymerization initiator used for copolymerizing the alkoxysilyl group-containing acrylic resin (a1) include known radical polymerization initiators such as 2,2 ' -azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide, t-butyl peroctoate, 2 ' -azobis (2-methylbutyronitrile), and 2,2 ' -azobis (2, 4-dimethylvaleronitrile).

The alkoxysilyl group-containing acrylic resin (a1) may be used alone or in combination of two or more.

The alkoxysilyl group-containing acrylic resin (a1) may contain a crosslinking-type functional group other than the alkoxysilyl group. Examples of the crosslinking-type functional group include a hydroxyl group, a carboxyl group, and an epoxy group. Among them, hydroxyl groups are preferable from the viewpoint of the scratch resistance, water resistance, curability, and finished appearance of the obtained coating film. Therefore, as the alkoxysilyl group-containing acrylic resin (a1), a hydroxyl group-and alkoxysilyl group-containing acrylic resin (a 1') can be preferably used.

Acrylic resin containing hydroxyl group and alkoxysilyl group (A1')

The acrylic resin (a 1') containing hydroxyl groups and alkoxysilyl groups is a resin having one or more hydroxyl groups and one or more alkoxysilyl groups in one molecule.

In the method for producing the alkoxysilyl group-containing acrylic resin (a1), the hydroxyl group-and alkoxysilyl group-containing acrylic resin (a 1') may be produced by using a hydroxyl group-containing polymerizable unsaturated monomer as one of the other polymerizable unsaturated monomers.

In the production of the hydroxyl group-and alkoxysilyl group-containing acrylic resin (a 1'), the amount of the hydroxyl group-containing polymerizable unsaturated monomer is preferably in the range of 5 to 60 mass%, more preferably 15 to 50 mass%, and even more preferably 25 to 45 mass%, based on the total amount of the comonomer components, from the viewpoint of scratch resistance, water resistance, curability, and finished appearance of the obtained coating film.

The hydroxyl value of the hydroxyl group-and alkoxysilyl group-containing acrylic resin (A1') is preferably 70 to 200mgKOH/g, more preferably 80 to 190mgKOH/g, and still more preferably 100 to 180mgKOH/g, from the viewpoint of scratch resistance, water resistance, curability, and finished product appearance of the obtained coating film.

As the hydroxyl group-and alkoxysilyl group-containing acrylic resin (a 1'), a secondary hydroxyl group-and alkoxysilyl group-containing acrylic resin (a1 ") can be used from the viewpoint of the finished appearance of the obtained coating film.

In the method of producing the hydroxyl group-and alkoxysilyl group-containing acrylic resin (a 1'), the secondary hydroxyl group-and alkoxysilyl group-containing acrylic resin (a1 ") may be produced by using a secondary hydroxyl group-containing polymerizable unsaturated monomer as one of the hydroxyl group-containing polymerizable unsaturated monomers.

As the secondary hydroxyl group-containing polymerizable unsaturated monomer, there may be mentioned: polymerizable unsaturated monomers having a secondary hydroxyl group, the alkyl group of the ester moiety of which has 2 to 8, preferably 3 to 6, more preferably 3 or 4 carbon atoms, such as 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 3-hydroxybutyl (meth) acrylate; adducts of (meth) acrylic acid with an epoxy group-containing compound (for example, Cardura E10P (manufactured by Hexion Specialty Chemicals Inc., trade name, glycidyl ester of synthetic highly branched saturated fatty acid (glycidyl neodecanoate)), and the like.) these may be used alone or in combination of two or more.

In the production of the secondary hydroxyl group-and alkoxysilyl group-containing acrylic resin (a1 "), the content thereof when a secondary hydroxyl group-containing polymerizable unsaturated monomer is used is in the range of 15 to 45 mass%, preferably 20 to 40 mass%, based on the total amount of the comonomer components, from the viewpoint of the finished appearance of the obtained coating film.

In the production of the secondary hydroxyl group-and alkoxysilyl group-containing acrylic resin (a1 "), the proportion of the secondary hydroxyl group-containing polymerizable unsaturated monomer in the total amount of the hydroxyl group-containing polymerizable unsaturated monomers is preferably in the range of 50 to 100 mass%, more preferably 55 to 100 mass%, and still more preferably 60 to 100 mass%, from the viewpoints of water resistance and finished appearance of the obtained coating film.

Other film-forming resins

In the coating composition of the present invention, as the film-forming resin of the binder component (a), a film-forming resin other than the alkoxysilyl group-containing acrylic resin (a1) is used in combination with the alkoxysilyl group-containing acrylic resin (a 1).

As the film-forming resin that can be used as the binder component (a) in combination with the alkoxysilyl group-containing acrylic resin (a1), a known film-forming resin that has been used as a binder component for paints can be used.

As the film-forming resin, acrylic resin, polyester resin, polyurethane resin, and alkyd resin can be used. These resins may be used alone or in combination of two or more.

The film-forming resin preferably contains crosslinking-type functional groups. The crosslinking functional group is preferably a hydroxyl group, a carboxyl group, or an epoxy group. Among them, the film-forming resin preferably contains a hydroxyl group from the viewpoint of water resistance of the obtained coating film.

As the film-forming resin other than the alkoxysilyl group-containing acrylic resin (a1), for example, a hydroxyl group-containing acrylic resin (a2) containing no alkoxysilyl group, a hydroxyl group-containing polyester resin, and a hydroxyl group-containing polyurethane resin are preferable.

Hydroxyl-containing acrylic resin not containing alkoxysilyl group (A2)

The hydroxyl group-containing acrylic resin (a2) containing no alkoxysilyl group can be obtained, for example, by copolymerizing a hydroxyl group-containing polymerizable unsaturated monomer with other polymerizable unsaturated monomers (polymerizable unsaturated monomers other than the alkoxysilyl group-containing polymerizable unsaturated monomer and the hydroxyl group-containing polymerizable unsaturated monomer).

Those mentioned above can be used as the hydroxyl group-containing polymerizable unsaturated monomer. As the polymerizable unsaturated monomers other than the alkoxysilyl group-containing polymerizable unsaturated monomer and the hydroxyl group-containing polymerizable unsaturated monomer, the monomers described in the above items (2) to (7) can be used.

The hydroxyl value of the hydroxyl group-containing acrylic resin (A2) containing no alkoxysilyl group is preferably from 70mgKOH/g to 200mgKOH/g, more preferably from 80mgKOH/g to 190mgKOH/g, and still more preferably from 100mgKOH/g to 180 mgKOH/g. The hydroxyl group-containing acrylic resin (A2) containing no alkoxysilyl group preferably has a weight average molecular weight of 2000 to 50000, more preferably 3000 to 30000, and still more preferably 4000 to 20000. The glass transition temperature of the hydroxyl group-containing acrylic resin (A2) containing no alkoxysilyl group is preferably-50 to 60 ℃, more preferably-10 to 50 ℃, and still more preferably 5 to 45 ℃.

From the viewpoint of the finished appearance of the obtained coating film, it is preferable to use the secondary hydroxyl group-containing acrylic resin (a 2') containing no alkoxysilyl group as the hydroxyl group-containing acrylic resin (a2) containing no alkoxysilyl group.

As the secondary hydroxyl group-containing acrylic resin (a 2') not containing an alkoxysilyl group, for example, it can be prepared by using a secondary hydroxyl group-containing polymerizable unsaturated monomer as one of the above-mentioned hydroxyl group-containing polymerizable unsaturated monomers in the method for preparing the hydroxyl group-containing acrylic resin (a2) not containing an alkoxysilyl group.

Examples of the secondary hydroxyl group-containing polymerizable unsaturated monomers include: polymerizable unsaturated monomers having a secondary hydroxyl group, the alkyl group of the ester moiety of which has 2 to 8, preferably 3 to 6, more preferably 3 or 4 carbon atoms, such as 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 3-hydroxybutyl (meth) acrylate; adducts of (meth) acrylic acid with an epoxy group-containing compound (for example, Cardura E10P (manufactured by Hexion Specialty Chemicals Inc., trade name, glycidyl ester of synthetic highly branched saturated fatty acid (glycidyl neodecanoate)), and the like.) these may be used alone or in combination of two or more.

In the production of the secondary hydroxyl group-containing acrylic resin (a2) containing no alkoxysilyl group, the content thereof when the secondary hydroxyl group-containing polymerizable unsaturated monomer is used is in the range of 15 to 45 mass%, and preferably 20 to 40 mass%, based on the total amount of the comonomer components, from the viewpoint of the finished appearance of the obtained coating film.

In the production of the secondary hydroxyl group-containing acrylic resin (a 2') not containing an alkoxysilyl group, the proportion of the secondary hydroxyl group-containing polymerizable unsaturated monomer in the total amount of the hydroxyl group-containing polymerizable unsaturated monomers is preferably in the range of 50 to 100% by mass, more preferably 55 to 100% by mass, and still more preferably 60 to 100% by mass, from the viewpoints of water resistance and finished appearance of the obtained coating film.

The hydroxyl value of the secondary hydroxyl group-containing acrylic resin (A2') not containing an alkoxysilyl group is preferably from 70mgKOH/g to 200mgKOH/g, more preferably from 80mgKOH/g to 190mgKOH/g, and still more preferably from 100mgKOH/g to 180 mgKOH/g. The weight average molecular weight of the secondary hydroxyl group-containing acrylic resin (A2') containing no alkoxysilyl group is preferably 2000 to 50000, more preferably 3000 to 30000, and still more preferably 4000 to 20000.

The hydroxyl group-containing polyester resin can be produced by a conventional method, for example, by esterification reaction of a polybasic acid and a polyhydric alcohol. The polybasic acid is a compound having two or more carboxyl groups in one molecule. Examples include: phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, fumaric acid, itaconic acid, trimellitic acid, pyromellitic acid, anhydrides thereof, and the like. A polyol is a compound having two or more hydroxyl groups in one molecule. Examples include: diols such as ethylene glycol, propylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 2-diethyl-1, 3-propanediol, neopentyl glycol, 1, 9-nonanediol, 1, 4-cyclohexanediol, neopentyl glycol hydroxypivalate, 2-butyl-2-ethyl-1, 3-propanediol, 3-methyl-1, 5-pentanediol, 2, 4-trimethylpentanediol, and hydrogenated bisphenol A; a tri-or higher polyol component such as trimethylolpropane, trimethylolethane, glycerol, and pentaerythritol; hydroxycarboxylic acids such as 2, 2-dimethylolpropionic acid, 2-dimethylolbutyric acid, 2-dimethylolvaleric acid, 2-dimethylolhexanoic acid, and 2, 2-dimethyloloctanoic acid; and so on.

In addition, for example, the obtained compound can be introduced into a polyester resin by reacting a monoepoxy compound such as an α -olefin epoxide (for example, propylene oxide, butylene oxide) or Cardura E10P (trade name, glycidyl ester of synthesized highly branched saturated fatty acid (glycidyl neodecanoate), manufactured by Hexion Specialty Chemicals inc.) with an acid.

The carboxyl group can be introduced into the polyester resin in a semi-esterified manner by, for example, adding an acid anhydride to the hydroxyl group-containing polyester.

The hydroxyl value of the hydroxyl group-containing polyester resin is preferably 80 to 250mg KOH/g, more preferably 100 to 200mg KOH/g. The hydroxyl group-containing polyester resin preferably has a weight average molecular weight of 500 to 3500, more preferably 500 to 2500.

Examples of the hydroxyl group-containing polyurethane resin include hydroxyl group-containing polyurethane resins obtained by reacting a polyol with a polyisocyanate.

Examples of low molecular weight polyols include: glycols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, and hexylene glycol; trihydric alcohols such as trimethylolpropane, glycerol and pentaerythritol; and so on. Examples of high molecular weight polyols include: polyether polyols, polyester polyols, acrylic polyols, epoxy polyols, and the like. Examples of polyether polyols include: polyethylene glycol, polypropylene glycol, polybutylene glycol, and the like. Examples of the polyester polyol include: polycondensates of the above-mentioned dihydric alcohols (alcohols such as dipropylene glycol, 1, 4-butanediol, 1, 6-hexanediol, and neopentyl glycol) with dibasic acids (for example, adipic acid, azelaic acid, or sebacic acid); polyols obtained by ring-opening polymerization of lactones (e.g., polycaprolactone); a polycarbonate diol; and so on. Polyols such as carboxyl-containing polyols, for example 2, 2-dimethylolpropionic acid and 2, 2-dimethylolbutyric acid, can also be used.

Examples of polyisocyanates that react with these polyols include: aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; biuret adducts and isocyanurate ring adducts of such polyisocyanates; alicyclic diisocyanates such as isophorone diisocyanate, 4' -methylenebis (cyclohexyl isocyanate), methylcyclohexane-2, 4- (or-2, 6-) diisocyanate, 1,3- (or 1,4-) bis (isocyanatomethyl) cyclohexane, 1, 4-cyclohexane diisocyanate, 1, 3-cyclopentane diisocyanate, and 1, 2-cyclohexane diisocyanate; biuret adducts and isocyanurate ring adducts of such polyisocyanates; aromatic diisocyanate compounds such as xylylene diisocyanate, m-xylylene diisocyanate, tetramethylxylylene diisocyanate, toluene diisocyanate, 4 ' -diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, 1, 4-naphthalene diisocyanate, 4-toluidine diisocyanate, 4 ' -diphenyl ether diisocyanate, (m-or p) -phenylene diisocyanate, 4 ' -diphenylene diisocyanate, 3 ' -dimethyl-4, 4 ' -diphenylene diisocyanate, bis (4-isocyanatophenyl) sulfone, and isopropylidene bis (4-phenylisocyanate); biuret adducts and isocyanurate ring adducts of such polyisocyanates; polyisocyanates having 3 or more isocyanate groups in one molecule, such as triphenylmethane-4, 4 ', 4 "-triisocyanate, 1,3, 5-triisocyanate, 2,4, 6-triisocyanate tolylene, and 4, 4' -dimethyldiphenylmethane-2, 2 ', 5, 5' -tetraisocyanate; biuret adducts and isocyanurate ring adducts of such polyisocyanates; and so on.

The hydroxyl value of the hydroxyl group-containing polyurethane resin is preferably 80 to 250mg KOH/g, more preferably 100 to 200mg KOH/g. The hydroxyl group-containing polyurethane resin preferably has a weight average molecular weight of 500 to 10000, more preferably 1000 to 5000.

Crosslinking agent (A3)

In the coating composition of the present invention, the binder component (a) may contain a crosslinking agent (a 3). The crosslinking agent (a3) is a compound that can react with the crosslinking-type functional group in the binder component (a) and form a crosslinked structure by reaction. The crosslinking-type functional group in the binder component (a) is preferably a hydroxyl group, and the crosslinking agent (a3) is preferably a compound reactive with a hydroxyl group. Particularly, when the alkoxysilyl group-containing acrylic resin (a1) in the adhesive component (a) is a hydroxyl group-and alkoxysilyl group-containing acrylic resin (a 1'), it is preferable, but not limited thereto.

Specific preferred examples of the crosslinking agent (a3) include: polyisocyanate compound, blocked polyisocyanate compound, amino resin, epoxy group-containing compound, carboxyl group-containing compound, carbodiimide compound. Among them, polyisocyanate compounds, blocked polyisocyanate compounds and amino resins which can react with hydroxyl groups are preferable. The crosslinking agent (a3) preferably contains a polyisocyanate compound from the viewpoint of finished appearance, scratch resistance, and the like.

The polyisocyanate compound is a compound having at least two isocyanate groups in one molecule. Examples include: aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, aromatic-aliphatic polyisocyanate compounds, aromatic polyisocyanate compounds, and derivatives of these polyisocyanate compounds, and the like.

Examples of the aliphatic polyisocyanate compounds include: aliphatic diisocyanate compounds such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate (1,2-propylene diisocyanate), 1,2-butylene diisocyanate (1,2-butylene diisocyanate), 2, 3-butylene diisocyanate, 1, 3-butylene diisocyanate, 2,4, 4-or 2,2, 4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and methyl 2, 6-diisocyanohexanoate (commonly known as lysine diisocyanate); aliphatic triisocyanate compounds such as 2-isocyanatoethyl 2, 6-diisocyanatohexanoate, 1, 6-diisocyanato-3-isocyanatomethylhexane, 1,4, 8-triisocyanatooctane, 1,6, 11-triisocyanatoundecane, 1, 8-diisocyanato-4-isocyanatomethyloctane, 1,3, 6-triisocyanatohexane, and 2,5, 7-trimethyl-1, 8-diisocyanato-5-isocyanatomethyloctane; and so on.

Examples of the alicyclic polyisocyanate compounds include: alicyclic diisocyanate compounds such as 1, 3-cyclopentene diisocyanate, 1, 4-cyclohexane diisocyanate, 1, 3-cyclohexane diisocyanate, 3-isocyanatomethyl-3, 5, 5-trimethylcyclohexyl isocyanate (commonly known under the name isophorone diisocyanate), 4-methyl-1, 3-cyclohexylene diisocyanate (commonly known under the name hydrogenated TDI), 2-methyl-1, 3-cyclohexylene diisocyanate, 1, 3-or 1, 4-bis (isocyanatomethyl) cyclohexane (commonly known as hydrogenated ditolyl diisocyanate) or mixtures thereof, and methylenebis (4, 1-cyclohexanediyl) diisocyanate (commonly known as hydrogenated MDI), and norbornane diisocyanate; alicyclic triisocyanate compounds, for example 1,3, 5-triisocyanatocyclohexane, 1,3, 5-trimethylisocyanocyclohexane, 2- (3-isocyanatopropyl) -2, 5-bis (isocyanatomethyl) -bicyclo (2.2.1) heptane, 2- (3-isocyanatopropyl) -2, 6-bis (isocyanatomethyl) -bicyclo (2.2.1) heptane, 3- (3-isocyanatopropyl) -2, 5-bis (isocyanatomethyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 1-isocyanatomethyl-3- (3-isocyanatopropyl) -heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane and 6- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane; and so on.

Examples of the aromatic-aliphatic polyisocyanate compound include: aromatic-aliphatic diisocyanate compounds, such as methylenebis (4, 1-phenylene) diisocyanate (commonly known as MDI), 1, 3-or 1, 4-xylylene diisocyanate or a mixture thereof, ω' -diisocyanato-1, 4-diethylbenzene, and 1, 3-or 1, 4-bis (1-isocyanato-1-methylethyl) benzene (commonly known as tetramethylxylylene diisocyanate) or a mixture thereof; aromatic-aliphatic triisocyanate compounds such as 1,3, 5-triisocyanatomethylbenzene; and so on.

Examples of the aromatic polyisocyanate compound include: aromatic diisocyanate compounds such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4 ' -diphenyl diisocyanate, 1, 5-naphthalene diisocyanate, 2, 4-toluene diisocyanate (commonly known as 2,4-TDI) or 2, 6-toluene diisocyanate (commonly known as 2,6-TDI) or a mixture thereof, 4 ' -toluidine diisocyanate, and 4,4 ' -diphenyl ether diisocyanate; aromatic triisocyanate compounds such as triphenylmethane-4, 4', 4 "-triisocyanate, 1,3, 5-triisocyanatobenzene, and 2,4, 6-triisocyanatotoluene; aromatic tetraisocyanate compounds such as 4,4 ' -diphenylmethane-2, 2 ', 5,5 ' -tetraisocyanate; and so on.

Examples of the polyisocyanate compound derivative include: dimers, trimers, biurets, allophanates, uretdiones, uretonimines, isocyanurates, oxadiazinetriones, polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI), crude TDI, and the like of the above polyisocyanate compounds.

The polyisocyanate compounds and derivatives thereof may be used alone or in combination of two or more.

From the viewpoint of weather resistance of the obtained coating film, at least one selected from the group consisting of an aliphatic polyisocyanate compound, an alicyclic polyisocyanate compound, and derivatives thereof is preferably used as the polyisocyanate compound. From the viewpoint of increasing the solid content of the obtained coating composition and the finished appearance and scratch resistance of the obtained coating film, it is more preferable to use the aliphatic polyisocyanate compound and/or its derivative.

As the aliphatic polyisocyanate compound and/or a derivative thereof, from the viewpoint of increasing the solid content of the obtained coating composition and the finished appearance and scratch resistance of the obtained coating film, it is preferable to use an aliphatic diisocyanate compound and/or an isocyanurate thereof, and it is more preferable to use hexamethylene diisocyanate and/or an isocyanurate thereof.

When the coating composition of the present invention contains the above polyisocyanate compound as the crosslinking agent (a3), the proportion of the polyisocyanate compound is preferably in the range of 5 to 60 parts by mass, preferably 15 to 50 parts by mass, more preferably 25 to 45 parts by mass, relative to 100 parts by mass of the solid content of the binder component (a), from the viewpoint of finished appearance and scratch resistance of the obtained coating film.

In the present specification, the solid content of the binder component (a) means: the total solid content of the alkoxysilyl group-containing acrylic resin (a1) as an essential component and the film-forming resin (for example, the hydroxyl group-containing acrylic resin (a2) containing no alkoxysilyl group) other than the alkoxysilyl group-containing acrylic resin (a1) and the crosslinking agent (A3) as optional components.

The blocked polyisocyanate compound usable as the crosslinking agent (a3) is a compound obtained by blocking the isocyanate group of the above polyisocyanate compound with a blocking agent.

Examples of the blocking agent include: phenol compounds such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; lactam compounds such as-caprolactam, -valerolactam, γ -butyrolactam, and β -propiolactam; aliphatic alcohol compounds such as methanol, ethanol, propanol, butanol, pentanol, and lauryl alcohol; ether compounds such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and methoxymethanol; alcohol compounds such as benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylolurea, methylolmelamine, diacetone alcohol, 2-hydroxyethyl acrylate, and ethyl 2-hydroxy (meth) acrylate; oxime compounds such as formamide oxime, acetamide oxime, acetyl oxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexane oxime; active methylene compounds such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone; thiol compounds such as butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, and ethylthiophenol; amide compounds such as acetanilide, methoxyacetanilide, N-acetyltoluidine (acetotoluide), acrylamide, methacrylamide, acetamide, stearamide, and benzamide; imide compounds such as succinimide, phthalimide, and maleimide; amine compounds such as diphenylamine, phenylnaphthylamine, dimethylaniline, N-phenyldimethylaniline, carbazole, aniline, naphthylamine, butylamine, dibutylamine, and butylaniline; imidazole compounds such as imidazole and 2-ethylimidazole; urea compounds such as urea, thiourea, ethylene urea, ethylene thiourea, and diphenyl urea; carbamate compounds such as phenyl N-phenylcarbamate (phenyl N-phenylcarbamate); imine compounds such as ethyleneimine (ethyleneimine) and propyleneimine (propyleneimine); sulfite compounds such as sodium hydrogen sulfite and potassium hydrogen sulfite; an azole compound; and so on. Examples of such azole compounds include: pyrazole or pyrazole derivatives such as pyrazole, 3, 5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3, 5-dimethylpyrazole, 4-nitro-3, 5-dimethylpyrazole, 4-bromo-3, 5-dimethylpyrazole and 3-methyl-5-phenylpyrazole; imidazole or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole and 2-phenylimidazole; imidazoline derivatives, such as 2-methylimidazoline and 2-phenylimidazoline; and so on.

Particularly preferred blocking agents are, for example: an oxime-based blocking agent, an active methylene-based blocking agent, and pyrazole or a pyrazole derivative.

When the end-capping is performed (reaction with an end-capping agent), a solvent may be added as necessary. As the solvent used in the blocking reaction, a solvent which does not react with an isocyanate group is preferably used. Examples include: ketones such as acetone and methyl ethyl ketone; esters, such as ethyl acetate; and solvents such as N-methyl-2-pyrrolidone (NMP).

When the coating composition of the present invention contains the above-mentioned blocked polyisocyanate compound as the crosslinking agent (a3), the proportion of the blocked polyisocyanate compound is preferably in the range of 5 to 60 parts by mass, preferably 15 to 50 parts by mass, more preferably 25 to 45 parts by mass, relative to 100 parts by mass of the solid content of the binder component (a), from the viewpoint of finished appearance and scratch resistance of the obtained coating film.

When the coating composition of the present invention contains the above polyisocyanate compound and/or blocked polyisocyanate compound as the crosslinking agent (a3), it is preferable that the equivalent ratio (NCO/OH) of the total amount of isocyanate groups (including blocked isocyanate groups) in the polyisocyanate compound and blocked polyisocyanate compound to the hydroxyl groups of the hydroxyl group-containing resin in the binder component (a) is generally in the range of 0.5 to 2 and preferably in the range of 0.8 to 1.5 from the viewpoints of water resistance and finished appearance of the obtained coating film.

Amino resins which can be used as the crosslinking agent (A3) include partially or fully methylolated amino resins obtained by reacting an amino component with an aldehyde component. Examples of amino components include: melamine, urea, benzoguanamine, acetoguanamine, stearguanamine, spiroguanamine, dicyandiamide, and the like. Examples of the aldehyde component include: formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, and the like.

Those obtained by etherification of part or all of the methylated groups of the above methylated amino resins with a suitable alcohol can also be used. Examples of alcohols useful for etherification include: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, 2-ethylbutanol, 2-ethylhexanol, and the like.

Preferably the amino resin is a melamine resin. Examples of useful melamine resins include alkyl etherified melamine resins obtained by etherifying part or all of the methylol groups of a partially or fully methylolated melamine resin with an alcohol.

Preferred examples of the alkyl etherified melamine resin include: a methyl-etherified melamine resin obtained by etherifying part or all of the methylol groups of a partially or fully methylolated melamine resin with methanol; a butyl-etherified melamine resin obtained by etherifying part or all of methylol groups of a partially or fully methylolated melamine resin with butanol; methyl-butyl mixed etherified melamine resin obtained by etherifying part or all of methylol groups of a partially or fully methylolated melamine resin with methanol and butanol; and so on.

The melamine resin preferably has a weight average molecular weight of 400 to 6000, more preferably 500 to 5000, and still more preferably 800 to 4000.

Commercially available products can be used as the melamine resin. Examples of commercially available products include: cymel 202, Cymel 203, Cymel 238, Cymel 251, Cymel303, Cymel323, Cymel324, Cymel325, Cymel327, Cymel350, Cymel385, Cymel 1156, Cymel 1158, Cymel 1116, Cymel 1130 (each manufactured by Allnex Japan inc.), U-VAN 120, U-VAN20 HS, U-VAN20 SE60, U-VAN 2021, U-VAN2028, U-VAN 28-60 (each manufactured by Mitsui Chemicals, inc.), and the like.

The melamine resin may be used alone or in combination of two or more.

When the coating composition of the present invention contains the above-mentioned amino resin as the crosslinking agent (a3), the proportion thereof is preferably in the range of 0.5 to 40 parts by mass, and preferably in the range of 1.0 to 15 parts by mass, more preferably 1.5 to 10 parts by mass, and further preferably 1.5 to 5 parts by mass, relative to 100 parts by mass of the solid content of the binder component (a), from the viewpoint of transparency, water resistance, and finished appearance of the obtained coating film.

The crosslinking agent (a3) may be used alone or in combination of two or more.

Rheology modifier (B)

The rheology modifier (B) comprises: (b1) a polyisocyanate compound, (b2) a primary monoamine having a number average molecular weight of 300 or less, and (b3) a polyetheramine having a number average molecular weight of more than 300 and less than 6000.

Polyisocyanate Compound (b1)

As the polyisocyanate compound (b1), for example, the polyisocyanate compounds described in the description of the crosslinking agent (A3) can be used.

The polyisocyanate compound (b1) is preferably an aliphatic polyisocyanate compound and/or a derivative thereof, more preferably an aliphatic diisocyanate compound and/or an isocyanurate thereof, from the viewpoint of transparency, water resistance and finished appearance of the obtained coating film. Among these, hexamethylene diisocyanate and/or isocyanurate thereof are preferable, and hexamethylene diisocyanate is more preferable.

A primary monoamine (b2) having a number average molecular weight of 300 or less

Examples of the primary monoamine (b2) having a number average molecular weight of 300 or less include: benzylamine, ethylamine, n-propylamine, sec-propylamine, n-butylamine, sec-butylamine, tert-butylamine, n-pentylamine, α -methylbutylamine, α -ethylpropylamine, β -ethylbutylamine, hexylamine, octylamine, 2-ethylhexylamine, n-decylamine, 1-aminooctadecane (stearylamine), cyclohexylamine, aniline, 2- (2-aminoethoxy) ethanol, and the like. The primary monoamine (b2) may be used alone or in combination of two or more.

The primary monoamine (b2) having a number average molecular weight of 300 or less is preferably a primary monoamine containing a benzene ring, and more preferably benzylamine, from the viewpoints of transparency, water resistance and finished appearance of the obtained coating film.

From the viewpoint of transparency, water resistance and finished appearance of the obtained coating film, the primary monoamine (b2) having a number average molecular weight of 300 or less preferably has a number average molecular weight of 60 to 300, more preferably 75 to 250, and still more preferably 90 to 150.

Polyetheramines having a number average molecular weight of greater than 300 and less than 6000 (b3)

The polyether amine (b3) is an amine having a number average molecular weight of more than 300 and less than 6000 and containing two or more ether bonds in one molecule.

In particular, from the viewpoint of transparency, water resistance and finished appearance of the obtained coating film, the number average molecular weight of the polyetheramine (b3) is preferably in the range of 300 to 4000, preferably 320 to 3000, more preferably 350 to 2000.

From the viewpoints of transparency, water resistance and finished appearance of the obtained coating film, the polyetheramine (b3) is preferably a primary amine.

From the viewpoint of transparency of the obtained coating film, the polyether amine (b3) is preferably at least one amine selected from the group consisting of monoamines, diamines, and triamines. In particular, the polyetheramine (b3) is more preferably a diamine from the viewpoint of transparency, water resistance and finished appearance of the obtained coating film.

Therefore, from the viewpoint of transparency, water resistance and finished appearance of the obtained coating film, the polyetheramine (b3) is preferably at least one amine selected from the group consisting of primary monoamines, primary diamines and primary triamines, more preferably a primary diamine. In the present invention, the primary diamine is a diamine having two-NH groups₂Amines of radicals, and primary triamines being of three-NH₂An amine of the group.

As the polyether amine (b3), for example, polyoxyalkylene (polyoxyalkylene) containing amines can be preferably used.

From the viewpoint of transparency of the obtained coating film, as the polyoxyalkylene containing amine, at least one amine compound selected from the group consisting of polyoxyalkylene containing monoamines (b3-1) represented by the following formula (1), polyoxyalkylene containing diamines (b3-2) represented by the following formula (3), and polyoxyalkylene containing polyamines (b3-3) having 3 or more amino groups represented by the following formula (6) can be preferably used.

Among them, polyoxyalkylene group-containing diamine (b3-2) can be particularly preferably used from the viewpoint of transparency, water resistance and finished appearance of the obtained coating film.

Monoamine containing polyoxyalkylene (b3-1)

The polyoxyalkylene group-containing monoamine (b3-1) is a polyoxyalkylene group-containing monoamine represented by the following formula (1).

In the formula, R¹Represents a monovalent organic compound, preferably a monovalent hydrocarbon group, more preferably C_1-4An alkyl group; r²Represents C_2-6Alkylene, preferably C_2-4Alkylene, more preferably selected from ethylene group, propylene group and tetramethylene groupup) at least one alkylene group of the group; m represents an integer of 2 to 70, preferably 4 to 60, more preferably 5 to 50; m oxyalkylene units (O-R)²) May be the same or different; when an oxyalkylene unit (O-R)²) Different from each other, oxyalkylene units (O-R)²) The addition form (polymerization form) of (b) may be a random type or a block type.

Specifically, as the polyoxyalkylene group-containing monoamine (b3-1), a polyoxyalkylene group-containing monoamine represented by the following formula (2) can be preferably used.

(wherein a represents an integer of 1 to 35, preferably 1 to 30, more preferably 1 to 25; and b represents an integer of 1 to 35, preferably 2 to 30, more preferably 3 to 25.)

Commercially available products can be used as the polyoxyalkylene group-containing monoamine (b 3-1). Examples of commercially available products include: JEFFAMINE M-600 (number average molecular weight 600; in the above formula (2), a is 1 and b is 9), JEFFAMINE M-1000 (number average molecular weight 1000; in the above formula (2), a is 19 and b is 3), JEFFAMINE M-2005 (number average molecular weight 2000; in the above formula (2), a is 6 and b is 29), JEFFAMINE M-2070 (number average molecular weight 2000; in the above formula (2), a is 31 and b is 10) manufactured by Huntsman Corporation, and the like.

Polyoxyalkylene group-containing diamine (b3-2)

The polyoxyalkylene containing diamine (b3-2) is a polyoxyalkylene containing diamine represented by the following formula (3).

In the formula, R³Represents C_2-6Alkylene, preferably C_2-4An alkylene group, more preferably at least one alkylene group selected from the group consisting of ethylene group, propylene group and tetramethylene group; r⁴Represents C_2-6Alkylene, preferably C_2-4An alkylene group, more preferably at least one alkylene group selected from the group consisting of ethylene group, propylene group and tetramethylene group; n represents an integer of 2-70, preferably 4-60, more preferably 5-50; n oxyalkylene units (O-R)⁴) May be the same or different; when an oxyalkylene unit (O-R)⁴) Different from each other, oxyalkylene units (O-R)⁴) The addition form (polymerization form) of (b) may be a random type or a block type.

Specifically, as the polyoxyalkylene containing diamine (b3-2), a polyoxyalkylene containing diamine represented by the following formula (4) is mentioned.

(wherein c represents an integer of 2 to 70, preferably 3 to 60, more preferably 4 to 50.)

And/or a polyoxyalkylene group-containing diamine represented by the following formula (5).

It is preferable to use (in the formula, d and f each represent an integer of 0 to 40, preferably 1 to 20, more preferably 1 to 10; e represents an integer of 2 to 40, preferably 4 to 35, more preferably 6 to 30; d + f is in the range of 1 to 80, particularly preferably 1 to 10, more preferably 2 to 9, and further more preferably 3 to 8).

A commercially available product can be used as the polyoxyalkylene containing diamine (b 3-2). Examples of commercially available products include: JEFFAMINE D-400 (number average molecular weight 430; in the above formula (4), c. apprxeq.6.1 (average)), JEFFAMINE D-2000 (number average molecular weight 2000; in the above formula (4), c. apprxeq.33), JEFFAMINE D-4000 (number average molecular weight 4000; in the above formula (4), c. apprxeq.68), JEFFAMINE ED-600 (number average molecular weight 600; in the above formula (5), D + f. apprxeq.3.6 (average), e. apprxeq.9), JEFFAMINE ED-900 (number average molecular weight 900; in the above formula (5), D + f. apprxeq.6, e. apprxeq.12.5 (average)), JEFFAMINE-2003 (number average molecular weight 2000; in the above formula (5), D + f. apprxeq.6, e. apprxeq.39), ELASTAMINERT-1000 (number average molecular weight 1000), Huntingan, and the like.

Polyoxyalkylene group-containing polyamine (b3-3)

The polyoxyalkylene containing polyamine (b3-3) is a polyoxyalkylene containing polyamine having 3 or more amino groups represented by the following formula (6).

In the formula, R⁵Represents a q-valent organic group having a carbon atom at the site bonded to the oxygen atom shown in the formula, preferably a q-valent hydrocarbon group; r⁶Represents C_2-6Alkylene, preferably C_2-4An alkylene group, more preferably at least one alkylene group selected from the group consisting of ethylene, propylene and tetramethylene; p represents an integer of 2-70, preferably 4-60, more preferably 5-50; q represents an integer of 3 or more, preferably 3 to 6, more preferably 3 or 4; p oxyalkylene units (O-R)⁶) May be the same or different; when an oxyalkylene unit (O-R)⁶) Different from each other, oxyalkylene units (O-R)⁶) The addition form (polymerization form) of (b) may be a random type or a block type.

Specifically, as the polyoxyalkylene polyamine (b3-3), a polyoxyalkylene-containing triamine represented by the following formula (7) and/or formula (8):

in the formula (7), g, h and i each represent an integer of 1 to 40, preferably 1 to 30, and more preferably 1 to 20; particularly, the sum g + h + i is preferably in the range of 3 to 40, preferably 4 to 30, and more preferably 5 to 20;

in the formula (8), j, k and r each represent an integer of 1 to 90, preferably 1 to 75, and more preferably 1 to 60; in particular, j + k + r is preferably in the range of 3 to 90, preferably 4 to 75, and more preferably 5 to 60.

A commercially available product can be used as the polyoxyalkylene group-containing polyamine (b 3-3). Examples of commercially available products include: JEFFAMINE T-403 (number average molecular weight 440; in the above formula (7), g + h + i is 5 to 6), JEFFAMINE T-3000 (number average molecular weight 3000; in the above formula (8), j + k + r ≈ 50), JEFFAMINE T-5000 (number average molecular weight 5000; in the above formula (8), j + k + r ≈ 85), manufactured by Huntsman Corporation, and the like.

Reaction method

The reaction of the polyisocyanate compound (b1), the primary monoamine (b2) having a number average molecular weight of 300 or less, and the polyetheramine (b3) having a number average molecular weight of more than 300 and less than 6000 can be usually carried out by mixing the components (b1) to (b3), raising the temperature as needed, and sampling an arbitrary method. The reaction is preferably carried out at 5 to 80 ℃ and more preferably at 10 to 60 ℃.

By this reaction, the carbonyl group of the polyisocyanate compound (b1), the amine of the primary monoamine (b2) having a number average molecular weight of 300 or less, and the polyether amine (b3) having a number average molecular weight of more than 300 and less than 6000 form a urea bond, thereby forming a crosslinked structure.

The components (b1) to (b3) can be mixed by an arbitrary method. Preferably, the polyisocyanate compound (b1) is added to the mixture of the primary monoamine (b2) and polyetheramine (b 3). Mixing may also be carried out in several stages as desired. The reactions of the components (b1) to (b3) are preferably carried out in the presence of an organic solvent.

Examples of the organic solvent include: aromatic solvents such as toluene, xylene, and Swasol 1000 (trade name, Cosmo Oil co., ltd., high boiling point petroleum solvent); aliphatic solvents such as mineral spirits; ester solvents such as ethyl acetate, butyl acetate, propyl propionate, butyl propionate, 1-methoxy-2-propyl acetate, 2-ethoxyethyl propionate, butyl 3-methoxyacetate, ethylene glycol ethyl ether acetate, and propylene glycol methyl ether acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone; alcohol solvents such as isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and 2-ethylhexanol; and so on.

From the viewpoint of transparency, water resistance and finished appearance of the obtained coating film, the proportions of the components (b1) to (b3) in the reactions of the components (b1) to (b3) are preferably in the following ranges based on the total amount of the components (b1) to (b 3):

polyisocyanate compound (b 1): 30 to 60 mass%, preferably 35 to 55 mass%, more preferably 40 to 50 mass%;

a primary monoamine (b2) having a number average molecular weight of 300 or less: 35 to 65 mass%, preferably 40 to 62 mass%, more preferably 45 to 60 mass%; and

polyetheramine (b3) having a number average molecular weight of more than 300 and less than 6000: 0.5 to 15% by mass, preferably 1 to 10% by mass, more preferably 1.5 to 8% by mass.

In the reaction of the components (b1) to (b3), the ratio (amino group/isocyanate group) of the total number of amino groups in the primary monoamine (b2) and the polyether amine (b3) to the number of isocyanate groups in the polyisocyanate compound (b1) is preferably in the range of 0.7 to 1.5, preferably 0.9 to 1.1, more preferably 0.95 to 1.05, from the viewpoints of transparency, water resistance and finished appearance of the obtained coating film.

In the present invention, the rheology-adjusting agent (B) may generally comprise a reaction product of the polyisocyanate compound (B1) and the primary monoamine (B2), and may further comprise a reaction product of the polyisocyanate compound (B1) and the polyether amine (B3), in addition to the reaction product of the polyisocyanate compound (B1), the primary monoamine (B2), and the polyether amine (B3).

From the viewpoint of suppressing aggregation of the reaction product, the reaction of the components (b1) to (b3) is preferably carried out in the presence of a resin component.

Examples of the resin component used for the reaction of components (b1) to (b3) include: acrylic resins, polyester resins, polyether resins, polycarbonate resins, polyurethane resins, epoxy resins, alkyd resins, and the like. Among them, acrylic resins are preferable from the viewpoint of transparency, water resistance and finished appearance of the obtained coating film. The resin component may be the binder component (a1) or a resin component different from the binder component (a). As the resin component, a film-forming resin other than the alkoxysilyl group-containing acrylic resin (a1), for example, a hydroxyl group-containing acrylic resin (a2) containing no alkoxysilyl group, is preferably used.

When the reaction of the components (b1) to (b3) is carried out in the presence of the above resin component, the mixing ratio of the components (b1) to (b3) and the resin component is preferably a ratio of the total mass of the components (b1) to (b3) to the mass of the resin component, that is, a ratio of the total mass of the components (b1) to (b3) to the mass of the resin component is 3/97 to 15/85, preferably 5/95 to 12/88.

In the present invention, when the reaction of the components (B1) to (B3) is carried out in the presence of the resin component, the resin component is not contained in the rheology modifier (B).

Coating composition

The coating composition of the present invention (hereinafter sometimes simply referred to as "coating of the present invention") is a coating composition comprising the rheology-adjusting agent (B) and the binder component (a) comprising the alkoxysilyl group-containing acrylic resin (a 1).

In the coating composition of the present invention, the content of the alkoxysilyl group-containing acrylic resin (a1) is preferably in the range of 5 to 80 parts by mass, preferably 10 to 60 parts by mass, and more preferably 15 to 40 parts by mass, based on 100 parts by mass of the total solid content of the binder component (a), from the viewpoint of scratch resistance, transparency, water resistance, and finished appearance of the obtained coating film.

In the coating composition of the present invention, the content of the rheology modifier (B) is preferably in the range of 0.1 to 3 parts by mass, preferably 0.2 to 2.7 parts by mass, and more preferably 0.3 to 2.5 parts by mass, based on 100 parts by mass of the total solid content of the binder component (a), from the viewpoints of transparency, water resistance, and finished appearance of the obtained coating film.

The coating composition of the present invention can form a coating film excellent in transparency, water resistance and finished appearance. The reason is presumed to be as follows:

a rheology modifier (B) comprising the reaction product of the polyisocyanate compound (B1), the primary monoamine (B2) having a number average molecular weight of 300 or less, and the polyetheramine (B3) having a number average molecular weight of more than 300 and less than 6000, forming a network in the coating composition to exert sag control ability, thereby improving finished product appearance. Further, by using the primary monoamine (B2) having a relatively low molecular weight and the polyetheramine (B3) having a relatively high molecular weight in combination as the amine component, the solubility of the rheology modifier (B) containing the reaction product at the time of forming a coating film is improved, and a coating film excellent in transparency and water resistance is formed.

The coating composition of the present invention may further contain a coloring pigment, an effect pigment, a pigment, and the like as necessary. The coating composition of the present invention may further contain extender pigments, ultraviolet absorbers, light stabilizers, catalysts, defoaming agents, rheology modifiers other than the above rheology modifier (B), rust inhibitors, surface modifiers, organic solvents, and the like.

Examples of the coloring pigment include: titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chrome yellow, chromium oxide, prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, vat-type dyes, perylene pigments, and the like.

Examples of effect pigments include: aluminum powder, mica powder, titanium oxide-coated mica powder, and the like.

Examples of extender pigments include: talc, clay, kaolin, barium oxide, barium sulfate, barium carbonate, calcium carbonate, alumina white, and the like.

The above pigments may be used alone or in combination of two or more.

When the coating composition of the present invention is used as a clear coating and contains a pigment, the amount of the pigment used is preferably not to impair the transparency of the obtained coating film. For example, the amount of the pigment is generally in the range of 0.1 to 20% by mass, preferably 0.3 to 10% by mass, and more preferably 0.5 to 5% by mass, based on the total solid content in the coating composition.

When the coating composition of the present invention is used as a colored coating and contains a pigment, the amount of the pigment is usually in the range of 1 to 200 mass%, preferably 2 to 100 mass%, more preferably 5 to 50 mass%, based on the total solid content in the coating composition.

In the present specification, "solid content" means a nonvolatile component such as a resin, a curing agent, and a pigment remaining in the coating composition after drying at 110 ℃ for 1 hour. For example, the total solids content of the coating composition can be calculated as follows. The coating composition is weighed in a heat-resistant container, such as an aluminum foil cup, dried at 110 ℃ for 1 hour after spreading on the bottom of the container, and then the mass of the ingredients in the coating composition remaining after drying is measured to determine the ratio of the mass of the remaining ingredients after drying to the total mass of the coating composition before drying.

Examples of the ultraviolet absorber include known ultraviolet absorbers such as benzotriazole absorbers, triazine absorbers, salicylic acid derivative absorbers, benzophenone absorbers and the like. These ultraviolet absorbers may be used alone or in combination of two or more.

When the coating composition of the present invention contains an ultraviolet absorber, the amount of the ultraviolet absorber is generally in the range of 0.1 to 10% by mass, preferably 0.2 to 5% by mass, more preferably 0.3 to 2% by mass, based on the total solid content in the coating composition.

Examples of the light stabilizer include known light stabilizers such as hindered amine light stabilizers.

As the hindered amine light stabilizer, a hindered amine light stabilizer having low basicity can be preferably used from the viewpoint of pot life. Examples of such hindered amine light stabilizers include acylated hindered amines, amino ether-based hindered amines, and the like. Specific examples include HOSTAVIN3058 (trade name, manufactured by Clariant), TINUVIN 123 (trade name, manufactured by BASF), and the like.

When the coating composition of the present invention contains a light stabilizer, the amount of the light stabilizer is generally in the range of 0.1 to 10 mass%, preferably 0.2 to 5 mass%, more preferably 0.3 to 2 mass%, based on the total solid content in the coating composition.

Examples of the catalyst include known catalysts. For example, when the coating composition of the present invention contains the above-mentioned polyisocyanate compound and/or blocked polyisocyanate compound as the crosslinking agent (a3), the coating composition of the present invention may contain a urethane reaction catalyst.

Specific examples of the urethane-forming reaction catalyst include: organic metal compounds such as tin octylate, dibutyltin diacetate, dibutyltin diisooctylate, dibutyltin dilaurate, dioctyltin diacetate (dioctyltin diacetate), dioctyltin di (2-ethylhexoate), dibutyltin oxide, dibutyltin sulfide, dioctyltin oxide, dibutyltin fatty acid salt, lead 2-ethylhexanoate, zinc octylate, zinc naphthenate, zinc fatty acid salt, bismuth octylate, bismuth 2-ethylhexanoate, bismuth oleate, bismuth neodecanoate, bismuth versatate, bismuth naphthenate, cobalt naphthenate, calcium octylate, copper naphthenate, and titanium tetrakis (2-ethylhexanol), tertiary amines, and the like, these may be used alone or in combination of two or more.

When the coating composition of the present invention contains the above-mentioned urethanization reaction catalyst, the amount of the urethanization reaction catalyst is preferably in the range of 0.005 to 2 mass%, more preferably 0.01 to 1 mass%, based on the total solid content in the coating composition of the present invention.

When the coating composition of the present invention contains the above-mentioned urethane reaction catalyst, the coating composition of the present invention may contain, from the viewpoints of storage stability, curability, and the like: organic acids such as acetic acid, propionic acid, butyric acid, isovaleric acid, caproic acid, 2-ethylbutyric acid, naphthenic acid, caprylic acid, pelargonic acid, capric acid, 2-ethylhexanoic acid, isooctanoic acid, isononanoic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, neodecanoic acid, versatic acid, isobutyric anhydride, itaconic anhydride, acetic anhydride, citraconic anhydride, propionic anhydride, maleic anhydride, butyric anhydride, citric anhydride, trimellitic anhydride, pyromellitic anhydride, and phthalic anhydride; inorganic acids such as hydrochloric acid and phosphoric acid; metal complexes such as acetylacetone and imidazole compounds; and so on.

When the above-mentioned melamine resin is used as the crosslinking agent (a3) in the coating composition of the present invention, the coating composition of the present invention may comprise: sulfonic acids such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid and the like are used as curing catalysts; alkyl phosphates such as monobutyl phosphoric acid, dibutyl phosphoric acid, mono (2-ethylhexyl) phosphoric acid, di (2-ethylhexyl) phosphoric acid, and the like; salts of such acids with amine compounds, and the like.

When the coating composition of the present invention contains a curing catalyst for melamine resin, the amount of the curing catalyst for melamine resin is preferably in the range of 0.1 to 2 mass%, preferably 0.2 to 1.7 mass%, more preferably 0.3 to 1.4 mass%, based on the total solid content in the coating composition of the present invention.

In a preferred embodiment, the coating composition of the present invention is an organic solvent-based coating composition, wherein the solvent mainly comprises an organic solvent.

Examples of the organic solvent include: aromatic solvents such as toluene, xylene, and Swasol 1000 (trade name, Cosmo Oil co., ltd., high boiling point petroleum solvent); ester solvents such as ethyl acetate, butyl acetate, propyl propionate, butyl propionate, 1-methoxy-2-propyl acetate, 2-ethoxyethyl propionate, ethyl 3-ethoxypropionate, butyl 3-methoxyacetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and methyl amyl ketone; alcohol solvents such as isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and 2-ethylhexanol; and so on. These may be used alone or in combination of two or more.

There is no particular limitation on the substrate coated with the coating composition of the present invention. Examples of such substrates include: exterior panel parts of automobile bodies such as passenger cars, trucks, motorcycles, and buses; automotive parts; exterior panel parts of household appliances such as cellular phones and audio devices; and so on. Particularly preferred are automobile bodies and outer panel parts of automobile parts.

The material of the substrate is not particularly limited. Examples include: metallic materials such as iron, aluminum, brass, copper, tin, stainless steel, galvanized alloy steel (Zn-Al, Zn-Ni, Zn-Fe, etc.); plastic materials such as polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin, and the like, and various FRPs; inorganic materials such as glass, cement, and concrete; wood; textile materials (e.g., paper and cloth); and so on. Among them, a metal material and a plastic material are preferable.

The substrate may be an article having a surface treatment such as a phosphate treatment, a chromate treatment, a complex oxide treatment or the like applied to the metal material listed above or a metal surface such as a vehicle body or the like formed therefrom. The substrate may be one having an undercoat film of various electrodeposition paints formed on the metal material, the vehicle body, or the like, or one having an intermediate coat film further formed on the undercoat film. The substrate may be a plastic material such as a bumper or the like having a primer coating film formed thereon.

There is no particular limitation on the method of applying a coating material comprising the coating composition of the present invention (hereinafter sometimes simply referred to as "coating material of the present invention"). For example, air spraying, airless spraying, rotary atomizing coating, curtain coating, or other coating methods may be used to form the wet coating film. Among these coating methods, electrostatic charge may be applied as needed, and among these methods, air spray coating or rotary atomization coating is particularly preferable. The coatings of the present invention are generally preferably applied to a cured film thickness of about 10 μm to 60 μm, more preferably 25 μm to 50 μm.

When air spraying, airless spraying or rotary atomizing coating is carried out, it is preferable to bring the viscosity of the coating material of the present invention within a viscosity range suitable for coating by appropriately adjusting with a solvent such as an organic solvent. The viscosity is generally in the range of 15 seconds to 60 seconds, and preferably in the range of 20 seconds to 40 seconds at 20 ℃ as measured with a Ford cup No.4 viscometer.

The wet coating film obtained by applying the coating material of the present invention to a substrate can be cured by heating. The heating may be performed by a known heating method. A drying furnace such as a hot-blast furnace electric furnace, an infrared induction heating furnace, or the like may be used. The heating temperature is not particularly limited, and is, for example, preferably in the range of 60 ℃ to 160 ℃, more preferably 80 ℃ to 140 ℃. The heating time is not particularly limited, and is, for example, preferably in the range of 10 minutes to 60 minutes, more preferably 15 minutes to 30 minutes.

The coating material of the present invention is a coating composition which can form a coating film having excellent scratch resistance, transparency, water resistance and finished appearance, and can be particularly suitably used as a top clear coat coating material. The coating material of the present invention can be suitably used as a coating material for automobiles in particular.

Method for forming multilayer coating film

The method of forming a multilayer coating film using the coating composition of the present invention as a top clear coat coating may include, for example, sequentially forming at least one pigmented base coat coating and at least one clear coat coating on a substrate, wherein the coating composition of the present invention is used as the clear coat coating forming the uppermost layer.

Specific examples of such a method include forming a multilayer coating film by a two-coat one-bake method, applying a colored base coat paint on a substrate on which an electrodeposition coating film and/or an intermediate coating film has been formed, preheating the obtained uncured coating film at, for example, 40 to 90 ℃ for about 3 to 30 minutes as necessary to promote evaporation of the solvent in the colored base coat paint, then applying the paint of the present invention as a clear coat paint to the uncured colored base coat film, and then curing the colored base coat film and the clear coating film at the same time.

The coating material of the present invention can also be suitably used as a top clear coat coating material for top coating in a three-coat two-bake system or a three-coat one-bake system.

The base coating paint used in the above manner may be a generally known thermosetting base coating paint, and specific examples include a paint obtained by combining a crosslinking agent (e.g., an amino resin, a polyisocyanate compound, or a blocked polyisocyanate compound) with a reactive functional group of a base resin (e.g., an acrylic resin, a polyester resin, an alkyd resin, or a urethane resin).

As the base coat paint, for example, a water-based paint, an organic solvent-based paint, or a powder paint may be used. From the viewpoint of finished appearance of the coating film and reduction of environmental load, an aqueous coating material is preferable.

When two or more clear coating films are formed in the method of forming a multilayer coating film, the coating material of the present invention or a known thermosetting clear coating material can be used as a clear coating material for forming layers other than the uppermost layer.