WO2010047195A1 - Coating composition and method for forming coating film - Google Patents

Abstract

A coating composition which is capable of forming a cured coating film having excellent abrasion resistance, acid resistance, contamination resistance and finish appearance. The coating composition is characterized by containing (A) a hydroxyl group-containing resin having a hydroxyl number of 80-200 mgKOH/g and a weight average molecular weight of 2,500-40,000, (B) a polyisocyanate compound and (C) an alkoxysilyl group-containing reaction product which is obtained by a reaction of a polycarbonate diol and an alkoxysilane compound, and has a hydroxyl number of 0-50 mgKOH/g and a number average molecular weight of 500-5,000.

Description

Coating composition and coating film forming method

The present invention relates to a coating composition having excellent scratch resistance, acid resistance and stain resistance.

Paints to be coated on an object such as an automobile body are required to have excellent coating performance such as scratch resistance, acid resistance, stain resistance, and finish.

Conventionally, melamine cross-linked paints have been widely used as paints for the above objects. The melamine cross-linking paint is a paint containing a hydroxyl group-containing resin and a melamine resin as a cross-linking agent, has a high cross-linking density at the time of heat curing, and is excellent in coating film performance such as scratch resistance and finish. However, this paint has a problem that the melamine cross-linking is easily hydrolyzed by acid rain, and the acid resistance of the coating film is poor.

Japanese Patent Laid-Open No. 6-220397 discloses a two-component urethane cross-linking coating composition comprising a hydroxyl group-containing acrylic resin, a hydroxyl group-containing oligoester and an isocyanate prepolymer. This paint is excellent in acid resistance of the coating film because urethane crosslinks are hardly hydrolyzed. However, the scratch resistance of the coating film is insufficient.

Japanese Patent Laid-Open No. 6-220397

An object of the present invention is to provide a coating composition capable of forming a cured coating film excellent in any of scratch resistance, acid resistance, stain resistance and finish.

As a result of intensive studies to solve the above problems, the present inventors have found that a hydroxyl group-containing resin having a specific hydroxyl value and an average molecular weight, a polyisocyanate compound, and an alkoxy obtained by a reaction between a polycarbonate diol and an alkoxysilane compound. The inventors have found that the above object can be achieved by a coating composition containing a reaction product having a hydroxyl group number and a number average molecular weight within a specific range having a silyl group, and has completed the present invention.

That is, the present invention is obtained by reacting a hydroxyl group-containing resin (A) having a hydroxyl value of 80 to 200 mgKOH / g and a weight average molecular weight of 2500 to 40000, a polyisocyanate compound (B), and a polycarbonate diol and an alkoxysilane compound. A coating composition comprising a reaction product (C) having an alkoxysilyl group and a hydroxyl value of 0 to 50 mgKOH / g and a number average molecular weight of 500 to 5000 is provided.

The present invention also relates to a method of forming a multilayer coating film by coating at least one layer of a colored base coat paint and at least one layer of a clear coat paint on an object to be coated. The present invention provides a method for forming a multilayer coating film characterized by coating the coating composition described above.

Furthermore, this invention provides the coated article obtained by the said multilayer coating-film formation method.

According to the coating composition of the present invention containing a specific hydroxyl group-containing resin and a polyisocyanate compound and a reaction product having a specific alkoxysilyl group obtained by a reaction between a specific polycarbonate diol and an alkoxysilane compound, Since the reaction product having a specific alkoxysilyl group obtained by the reaction with the alkoxysilane compound has good compatibility with the hydroxyl group-containing resin and the polyisocyanate compound, a coating film with good finish can be obtained. it can.

In addition, the reaction product having the alkoxysilyl group can improve the physical properties of the coating film such as mechanical strength, urethane crosslinking by the reaction of the hydroxyl group-containing resin and the polyisocyanate compound, and the reaction product having the alkoxysilyl group. Scratch resistance, acid resistance, and contamination resistance because the bond between the alkoxysilyl group and the hydroxyl group, the condensation bond between the alkoxysilyl groups, and the carbonate bond of the reaction product having the alkoxysilyl group are excellent in acid hydrolysis resistance. The effect that the cured coating film excellent in all, such as property can be formed can be show | played.

Hereinafter, the coating composition of the present invention (hereinafter sometimes referred to as “the present coating”) and the method for forming a multilayer coating film will be described in detail.

The coating composition of the present invention comprises a hydroxyl group-containing resin (A) having a hydroxyl value of 80 to 200 mgKOH / g and a weight average molecular weight of 2500 to 40000, a polyisocyanate compound (B), and a reaction between a polycarbonate diol and an alkoxysilane compound. A coating composition comprising a reaction product (C) having an alkoxysilyl group and having a hydroxyl value of 0 to 50 mgKOH / g and a number average molecular weight of 500 to 5000.

Hydroxyl-containing resin (A)
The hydroxyl group-containing resin (A) contained in the coating composition of the present invention is a hydroxyl group-containing resin having a hydroxyl value of 80 to 200 mgKOH / g and a weight average molecular weight of 2500 to 40,000.

The hydroxyl group-containing resin (A) is not particularly limited as long as the hydroxyl value is in the range of 80 to 200 mgKOH / g and the weight average molecular weight is in the range of 2500 to 40000. Specifically, for example, acrylic resin, polyester resin, A polyether resin, a polyurethane resin, etc. can be mentioned, As a preferable thing, a hydroxyl-containing acrylic resin, a hydroxyl-containing polyester resin, and a hydroxyl-containing polyurethane resin, More preferably, a hydroxyl-containing acrylic resin can be mention | raise | lifted.

In a preferred embodiment of the present invention, the hydroxyl group-containing acrylic resin is obtained by copolymerizing a hydroxyl group-containing unsaturated monomer (M-1) and other copolymerizable unsaturated monomer (M-2) by a conventional method. Can be manufactured.

The hydroxyl group-containing unsaturated monomer (M-1) is a compound having one hydroxyl group and one unsaturated bond in one molecule, and this hydroxyl group mainly functions as a functional group that reacts with a crosslinking agent. . Specifically, the monomer is preferably a monoester product of acrylic acid or methacrylic acid and a dihydric alcohol having 2 to 10 carbon atoms, such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl. Acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyheptyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxynonyl (meth) acrylate , Hydroxydecyl (meth) acrylate, etc., more preferably 2-hydroxyethyl (meth) acrylate, hydroxypropyl acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl ( Data) acrylate, and the like can be mentioned. In addition, other monoesterified products of polyhydric alcohol and acrylic acid or methacrylic acid are compounds obtained by ring-opening condensation of ε-caprolactone, such as “Placcel FA-1”, “Placcel FA-2”, “Placcel” FA-3, Plaxel FA-4, Plaxel FA-5, Plaxel FM-1, Plaxel FM-2, Plaxel FM-3, Plaxel FM-4, Plaxel FM −5 ”(all of which are trade names, manufactured by Daicel Chemical Industries, Ltd.).

The blending ratio of the hydroxyl group-containing unsaturated monomer (M-1) is preferably 20 to 50% by mass, particularly 25 to 45% by mass based on the total amount of the monomer mixture.

By setting the blending ratio of the hydroxyl group-containing unsaturated monomer (M-1) within the above range, the cured coating film is sufficiently cross-linked to obtain a predetermined scratch resistance, and other copolymerization is possible. The compatibility with the unsaturated monomer (M-2) and the compatibility between the obtained hydroxyl group-containing acrylic resin and the other components (polyisocyanate compound (B) and reaction product (C)) are sufficiently high. It is preferable because the finished appearance of the coating film is also good.

In the present specification, “(meth) acrylate” means “acrylate or methacrylate”.

The other copolymerizable unsaturated monomer (M-2) is a compound having one unsaturated bond in one molecule other than the hydroxyl group-containing unsaturated monomer (M-1). Specific examples are listed below in (1) to (8).

(1) Acid group-containing unsaturated monomer: a compound having one or more acid groups and one unsaturated bond in one molecule, such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic Carboxyl group-containing unsaturated monomers such as acid and maleic anhydride; sulfonic acid group-containing unsaturated monomers such as vinyl sulfonic acid and sulfoethyl (meth) acrylate; 2- (meth) acryloyloxyethyl acid phosphate; Examples include acidic phosphate ester unsaturated monomers such as 2- (meth) acryloyloxypropyl acid phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, and 2-methacryloyloxyethylphenyl phosphate be able to. These can be used alone or in combination of two or more. The acid group-containing unsaturated monomer can also act as an internal catalyst when the component (A) undergoes a crosslinking reaction with the crosslinking agent, and the amount used thereof is the total amount of the monomer mixture constituting the hydroxyl group-containing acrylic resin. Is preferably used in the range of 0 to 5% by mass, particularly 0.1 to 3% by mass.

(2) Monoesterified product of acrylic acid or methacrylic acid and a monohydric alcohol having 1 to 20 carbon atoms: for example, methyl (meth) acrylate, ethyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (Meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isomyristyl (meth) acrylate, isostearyl acrylate (Osaka Organic Chemical Industry) Product name), cyclohexyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, adamantyl (meth) acrylate, 3,5-dimethyl Damantyl (meth) acrylate, 3-tetracyclododecyl methacrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, 4-methylcyclohexylmethyl (meth) acrylate, 4-ethylcyclohexylmethyl (meth) acrylate, 4-methoxycyclohexyl Methyl (meth) acrylate, tert-butylcyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate, cyclododecyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and the like.

When the monomer (2) is used as a constituent component, the blending ratio is preferably 3 to 50% by mass, particularly 10 to 40% by mass based on the total amount of the monomer mixture.

(3) alkoxysilane group-containing unsaturated monomer: for example, vinyltrimethoxysilane, vinyltriethoxysilane, acryloxyethyltrimethoxysilane, methacryloxyethyltrimethoxysilane, acryloxypropyltrimethoxysilane, methacryloxypropyltri Methoxysilane, acryloxypropyltriethoxysilane, methacryloxypropyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, etc. Among these, preferable alkoxysilane group-containing unsaturated monomers include vinyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like.

By using an alkoxysilane group-containing unsaturated monomer as a constituent component, in addition to the crosslinking bond between the hydroxyl group and the isocyanate group, a condensation reaction between the alkoxysilane groups and a crosslinking bond caused by the reaction between the alkoxysilane group and the hydroxyl group are generated. Can do. Thereby, since the crosslinking density of the obtained coating film improves, the effect of an improvement in acid resistance and stain resistance can be obtained.
When an alkoxysilane group-containing unsaturated monomer is used as a constituent component, the blending ratio is preferably 3 to 50% by mass, particularly 5 to 35% by mass based on the total amount of the monomer mixture. .

(4) Aromatic unsaturated monomer: for example, styrene, α-methylstyrene, vinyl toluene, etc. By using an aromatic unsaturated monomer as a constituent component, the Tg of the resulting resin increases, Since a hydrophobic coating film having a high refractive index can be obtained, it is possible to obtain the effects of improving the finish by improving the gloss of the coating film and improving the water resistance and acid resistance.

When an aromatic unsaturated monomer is used as a constituent component, the blending ratio is preferably in the range of 3 to 50% by mass, particularly 5 to 40% by mass based on the total amount of the monomer mixture.

(5) Glycidyl group-containing unsaturated monomer: A compound having one glycidyl group and one unsaturated bond in each molecule, specifically, glycidyl acrylate, glycidyl methacrylate, and the like.

(6) Nitrogen-containing unsaturated monomers: for example, (meth) acrylamide, dimethylacrylamide, N, N-dimethylpropylacrylamide, N-butoxymethylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, diacetoneacrylamide, N, N-dimethylaminoethyl (meth) acrylate, vinylpyridine, vinylimidazole and the like.

(7) Other vinyl compounds: For example, vinyl acetate, vinyl propionate, vinyl chloride, versatic acid vinyl ester Veova 9, Veova 10 (Japan Epoxy Resin), etc.

(8) Unsaturated bond-containing nitrile compound: For example, acrylonitrile, methacrylonitrile and the like.

These other vinyl monomers (M-2) can be used alone or in combination of two or more.

A hydroxyl group-containing acrylic resin can be obtained by copolymerizing a monomer mixture comprising the monomers (M-1) and (M-2).

As a hydroxyl group-containing acrylic resin for making a coating composition excellent in both coating film performance such as scratch resistance, acid resistance and stain resistance and finish of the coating film, a monomer (M- Particularly preferred is a hydroxyl group-containing acrylic resin obtained by copolymerizing a monomer mixture comprising 1) and (M-2).

(A) 20-50% by mass of a hydroxyl group-containing unsaturated monomer, (b) 0-60% by mass of a monoester product of acrylic acid or methacrylic acid and a monohydric alcohol having 1-20 carbon atoms, and (c) aroma. Hydroxyl group-containing acrylic resin obtained by copolymerizing a monomer mixture composed of 0 to 40% by mass of an aliphatic unsaturated monomer.

The copolymerization method for copolymerizing the monomer mixture to obtain a hydroxyl group-containing acrylic resin is not particularly limited, and a known copolymerization method can be used. A solution polymerization method in which polymerization is carried out in the presence of a polymerization initiator can be preferably used.

Examples of the organic solvent used in the solution polymerization method include aromatic solvents such as toluene, xylene, and swazole 1000 (trade name, high-boiling petroleum solvent) manufactured by Cosmo Oil; ethyl acetate, 3-methoxybutyl Ester solvents such as acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, propyl propionate, butyl propionate, ethoxy ethyl propionate, etc. Can be mentioned.

These organic solvents can be used alone or in combination of two or more. However, since the hydroxyl group-containing acrylic resin used in the coating material has a high hydroxyl value, it has a high boiling point in terms of the solubility of the resin. It is preferable to use an ester solvent or a ketone solvent. In addition, aromatic solvents having higher boiling points can be suitably used in combination.

Examples of the polymerization initiator that can be used in the copolymerization of the hydroxyl group-containing acrylic resin include 2,2′-azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide, Mention may be made of radical polymerization initiators known per se, such as t-butyl peroctoate and 2,2′-azobis (2-methylbutyronitrile).

The hydroxyl value of the hydroxyl group-containing acrylic resin is in the range of 80 to 200 mgKOH / g, more preferably in the range of 90 to 190 mgKOH / g. When the hydroxyl value is less than 80 mgKOH / g, the scratch resistance may be insufficient due to the low crosslinking density. On the other hand, if it exceeds 200 mgKOH / g, the water resistance of the coating film may decrease.

The weight average molecular weight of the hydroxyl group-containing acrylic resin is in the range of 2500 to 40000, more preferably in the range of 5000 to 30000. It is preferable to use a hydroxyl group-containing acrylic resin having a weight average molecular weight in the above range because the coating film performance such as acid resistance is high, the coating film is smooth and the finish is good.

In addition, in this specification, a weight average molecular weight is the value which converted the weight average molecular weight measured with the gel permeation chromatograph (The Tosoh company make, "HLC8120GPC") on the basis of the weight average molecular weight of polystyrene. Columns are “TSKgel G-4000H × L”, “TSKgel G-3000H × L”, “TSKgel G-2500H × L”, “TSKgel G-2000H × L” (all manufactured by Tosoh Corporation, trade names) ), Mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 cc / min, detector: RI. The number average molecular weight is also a value measured under the same conditions as described above.

The glass transition temperature of the hydroxyl group-containing acrylic resin is preferably in the range of −40 ° C. to 85 ° C., particularly in the range of −30 ° C. to 80 ° C. When the glass transition temperature is less than −40 ° C., the coating film hardness may be insufficient, and when it exceeds 85 ° C., the coated surface smoothness of the coating film may be deteriorated.

The hydroxyl group-containing polyester resin that can be used as the hydroxyl group-containing resin (A) can be produced by a conventional method, for example, by an esterification reaction between a polybasic acid and a polyhydric alcohol. The polybasic acid is a compound having two or more carboxyl groups in one molecule. For example, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic acid, hexa And hydrophthalic acid, maleic acid, fumaric acid, itaconic acid, trimellitic acid, pyromellitic acid and their anhydrides. The polyhydric alcohol contains two or more hydroxyl groups in one molecule. For example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-diethyl-1,3 -Propanediol, neopentyl glycol, 1,9-nonanediol, 1,4-cyclohexanediol, hydroxypi Diols such as neopentyl glycol phosphate, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethylpentanediol, and hydrogenated bisphenol A And trivalent or higher polyol components such as trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, and the like, and 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylol Examples thereof include hydroxycarboxylic acids such as pentanoic acid, 2,2-dimethylolhexanoic acid, and 2,2-dimethyloloctanoic acid.

In addition, a monoepoxy compound such as propylene oxide and butylene oxide, a monoepoxy compound such as Cardura E10 (product name, glycidyl ester of a synthetic highly branched saturated fatty acid) such as Cardura E10 is reacted with an acid, A compound may be introduced into the polyester resin.

When introducing a carboxyl group into a polyester resin, for example, it can also be introduced by adding an acid anhydride to a hydroxyl group-containing polyester and half-esterifying it.

The hydroxyl value of the hydroxyl group-containing polyester resin is in the range of 80 to 200 mgKOH / g, more preferably in the range of 100 to 170 mgKOH / g. By setting the hydroxyl value within the above range, a sufficiently high scratch resistance is obtained and the water resistance of the coating film is high, which is preferable.

The weight average molecular weight of the hydroxyl group-containing polyester resin is in the range of 2500 to 40000, more preferably in the range of 5000 to 30000.

It is preferable to use a hydroxyl group-containing polyester resin having a weight average molecular weight within the above range because a paint having high coating performance such as acid resistance and coating surface smoothness can be obtained.

The glass transition temperature of the hydroxyl group-containing polyester resin is preferably in the range of −40 ° C. to 85 ° C., particularly in the range of −30 ° C. to 80 ° C. Use of a hydroxyl group-containing polyester resin having a glass transition temperature in the above range is preferable because sufficiently high coating film hardness and coating surface smoothness can be obtained.

The hydroxyl group-containing resin (A) also includes so-called urethane-modified acrylic resins and urethane-modified polyester resins.

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

Examples of the polyol include dihydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, and hexamethylene glycol, and trivalent or higher alcohols such as trimethylolpropane, glycerin, pentaerythritol, and sorbitol. Etc. Examples of the high molecular weight material include polyether polyol, polyester polyol, acrylic polyol, and epoxy polyol. Examples of the polyether polyol include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Examples of the polyester polyol include alcohols such as the aforementioned dihydric alcohols, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol, and dibasic acids such as adipic acid, azelaic acid, and sebacic acid. Lactone-based ring-opening polymer polyol such as polycaprolactone, polycarbonate diol, and the like. In addition, carboxyl group-containing polyols such as 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid can also be used.

Examples of the polyisocyanate to be reacted with the above polyol include aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; and burette type addition of these polyisocyanates. , Isocyanurate cycloadduct; isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4- (or -2,6-) diisocyanate, 1,3- (or 1,4-) Alicyclic diisocyanates such as di (isocyanatomethyl) cyclohexane, 1,4-cyclohexane diisocyanate, 1,3-cyclopentane diisocyanate, 1,2-cyclohexane diisocyanate And burette type adducts, isocyanurate cycloadducts of these polyisocyanates; xylylene diisocyanate, metaxylylene diisocyanate, tetramethylxylylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene Diisocyanate, 1,4-naphthalene diisocyanate, 4,4-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, (m- or p-) phenylene diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethyl-4 , 4'-biphenylene diisocyanate, bis (4-isocyanatophenyl) sulfone, isopropylidenebis (4-phenylisocyanate), etc. And burette-type adducts, isocyanurate cycloadducts of these polyisocyanates; triphenylmethane-4,4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatobenzene, 2, Polyisocyanates having three or more isocyanate groups in one molecule such as 4,6-triisocyanatotoluene, 4,4′-dimethyldiphenylmethane-2,2 ′, 5,5′-tetraisocyanate; And polyisocyanate burette type adducts, isocyanurate ring adducts, and the like.

The hydroxyl value of the hydroxyl group-containing polyurethane resin is in the range of 80 to 200 mgKOH / g, more preferably in the range of 100 to 170 mgKOH / g. When the hydroxyl value is less than 80 mgKOH / g, the scratch resistance may be insufficient, and when it exceeds 200 mgKOH / g, the water resistance of the coating film may be lowered.

The weight average molecular weight of the hydroxyl group-containing polyurethane resin is in the range of 2500 to 40000, more preferably in the range of 5000 to 30000. When the weight average molecular weight is less than 2500, the coating performance such as acid resistance may be deteriorated, and when it exceeds 40000, the coating surface smoothness of the coating may be deteriorated.

The glass transition temperature of the hydroxyl group-containing polyurethane resin is preferably −40 ° C. to 85 ° C., particularly preferably within the range of −30 ° C. to 80 ° C. When the glass transition temperature is less than −40 ° C., the coating film hardness may be insufficient, and when it exceeds 85 ° C., the coated surface smoothness of the coating film may be deteriorated. The hydroxyl group-containing resin (A) can be used alone or in combination of two or more. As the hydroxyl group-containing resin (A), a hydroxyl group-containing acrylic resin or a hydroxyl group-containing polyester resin can be suitably used.

Polyisocyanate compound (B)
The polyisocyanate compound (B) of the coating composition of the present invention is a compound having two or more free isocyanate groups in one molecule, and those conventionally used in the production of polyurethane can be used. Examples thereof include aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of these polyisocyanates.

Examples of the aliphatic polyisocyanate include compounds having 2 to 3 isocyanate groups having a straight or molecular chain saturated or unsaturated, aliphatic hydrocarbon or fatty acid having 3 to 8 carbon atoms as a skeleton. Can be mentioned. More specifically, for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene Aliphatic diisocyanates such as diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, lysine ester triisocyanate, 1,4,8-triisocyanate Octane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, 2,5,7-trimethyl-1,8- Aliphatic triisocyanates such as isocyanato-5-isocyanatomethyl-octane and the like.

Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: Isophorone diisocyanate), 4,4'-methylenebis (cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane ( Common name: hydrogenated xylylene diisocyanate) or mixtures thereof, alicyclic diisocyanates such as norbornane diisocyanate, for example, 1,3,5-triisocyanatocyclohexane, 1,3 5-trimethylisocyanatocyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 2- (3-isocyanatopropyl) -2, 6-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 3- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 6- (2-isocyanatoethyl) -2-isocyanato Methyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanato (Lopyl) -bicyclo (2.2.1) -heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, etc. Alicyclic triisocyanate and the like.

Examples of the araliphatic polyisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω′-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis ( 1-isocyanato-1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or a mixture thereof, for example, an araliphatic triisocyanate such as 1,3,5-triisocyanatomethylbenzene Etc.

Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4′- or 4,4′-diphenylmethane diisocyanate, or a mixture thereof. 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, aromatic diisocyanates such as 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate, for example, triphenylmethane-4,4 ′, 4 "Aromatic triisocyanates such as -triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, such as 4,4'-diphenylmethane-2,2 ', 5,5 '-Tetraiso It can be mentioned aromatic tetracarboxylic isocyanates such as Aneto.

Examples of the polyisocyanate derivative include dimer, trimer, burette, allophanate, carbodiimide, uretdione, uretoimine, isocyanurate, oxadiazine trione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric). MDI) and crude TDI.

These polyisocyanate compounds may be used alone or in combination of two or more. Of these polyisocyanate compounds, aliphatic diisocyanates and derivatives thereof can be suitably used from the viewpoint of scratch resistance, weather resistance, and the like.

Moreover, the blocked polyisocyanate compound which is the compound which blocked the isocyanate group of the polyisocyanate compound which has a 2 or more free isocyanate group in 1 molecule mentioned above with the blocking agent as a polyisocyanate compound can also be used.

The blocking agent blocks a free isocyanate group. For example, when heated to 100 ° C. or higher, preferably 130 ° C. or higher, the isocyanate group is regenerated and can easily react with a hydroxyl group. Examples of such blocking agents include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and hydroxybenzoic acid methyl; ε-caprolactam, δ-valerolactam, Lactams such as γ-butyrolactam and β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono Butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, pro Ethers such as lenglycol monomethyl ether and methoxymethanol; benzyl alcohol; glycolic acid; glycolic acid esters such as methyl glycolate, ethyl glycolate and butyl glycolate; lactic acid esters such as lactic acid, methyl lactate, ethyl lactate and butyl lactate; Alcohols such as methylol urea, methylol melamine, diacetone alcohol, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate; oximes such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime System: Active methylene system such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone Butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol and other mercaptans; Acid amides such as stearamide, benzamide; imides such as succinimide, phthalimide, maleic imide; diphenylamine, phenylnaphthylamine, xylidine, N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine, di Amines such as butylamine and butylphenylamine; Imidazoles such as imidazole and 2-ethylimidazole; 3,5-dimethylpyra Pyrazoles such as urea; ureas such as urea, thiourea, ethylene urea, ethylene thiourea and diphenyl urea; carbamate esters such as phenyl N-phenylcarbamate; imines such as ethyleneimine and propyleneimine; bisulfite Examples of the blocking agent include sulfites such as soda and potassium bisulfite.

In performing the blocking (reacting the blocking agent), a solvent can be added as necessary. The solvent used for the blocking reaction is preferably not reactive to isocyanate groups, for example, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, and solvents such as N-methylpyrrolidone (NMP). Can give.

Polyisocyanate compound (B) can be used alone or in combination of two or more.

Reaction product (C)
The reaction product (C) of this paint is a reaction product having a hydroxyl value of 0 to 50 mgKOH / g and a number average molecular weight of 500 to 5000 having an alkoxysilyl group obtained by reaction of a polycarbonate diol and an alkoxysilane compound.

The hydroxyl value of the reaction product (C) is determined by the compatibility with the hydroxyl group-containing resin (A) and the polyisocyanate compound (B), the curability of the resulting coating composition and the acid resistance and scratch resistance of the resulting coating film. From the viewpoint, it is 0 to 50 mgKOH / g, preferably 0 to 30 mgKOH / g.

The reaction product (C) can be synthesized by reacting a polycarbonate diol and an alkoxysilane compound.

Polycarbonate diol is usually a compound obtained by polycondensation reaction of a diol and a carbonylating agent.

The diol component of the polycarbonate diol used for the synthesis of the reaction product (C) is preferably a divalent alcohol having 2 to 10 carbon atoms, particularly 4 to 8 carbon atoms. Specifically, for example, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, , 7-heptanediol, 1,8-octanediol, 2-ethyl-1,6-hexanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, etc. Aliphatic systems such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and the like; aromatic systems such as p-xylenediol and p-tetrachloroxylenediol; Examples thereof include diols such as diethylene glycol and dipropylene glycol. These diols can be used alone or in combination of two or more.

The polycarbonate diol used for the synthesis of the reaction product (C) is preferably one obtained by polycondensing a diol component containing 1,6-hexanediol and a carbonylating agent from the viewpoint of durability and hardness.

Further, as a particularly preferred one, 1,6-hexanediol is used as an essential diol component, and two or more diol components are used in combination, and a combination of 1,6-hexanediol and 1,5-pentanediol, Polycarbonate diol obtained by polycondensation of a diol component such as a combination of 1,6-hexanediol and 1,4-butanediol, or a combination of 1,6-hexanediol and 1,4-cyclohexanedimethanol with a carbonylating agent Can give.

As the carbonylating agent, for example, one or a combination of two or more commonly used alkylene carbonates, dialkyl carbonates, diallyl carbonates and phosgenes can be used. Of these, preferred are ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate and the like.

As the polycarbonate diol used for the synthesis of the reaction product (C), it is preferable to use one having a viscosity at 50 ° C. of 10,000 mPa · s or less. When the viscosity at 50 ° C. exceeds 10,000 mPa · s, handling may be difficult, and the obtained reaction product (C) is compatible with the hydroxyl group-containing resin (A) and the polyisocyanate compound (B). Since it becomes inferior, the glossiness of a coating film, white turbidity, etc. arise, and the finish of a coating film may become inferior.

The viscosity of the polycarbonate diol used for the synthesis of the reaction product (C) is preferably 10,000 mPa · s or less, more preferably 8000 mPa · s or less, and even more preferably 5000 mPa · s or less at 50 ° C. The viscosity is a value measured at 50 ° C. using a B-type viscometer under the condition of 6 rpm.

The number average molecular weight of the polycarbonate diol used for the synthesis of the reaction product (C) is preferably from 300 to 2000, more preferably from 500 to 1800, and even more preferably from 700 to 2000, from the viewpoint of acid resistance and scratch resistance of the coating film. 1500.

In the present specification, the number average molecular weight is a value calculated based on the molecular weight of standard polystyrene from the chromatogram measured by gel permeation chromatograph. As the gel permeation chromatograph, “HLC8120GPC” (manufactured by Tosoh Corporation) was used. Four columns, “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”, “TSKgel G-2000HXL” (both manufactured by Tosoh Corporation), are used as columns. Mobile phase: Tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 cc / min, detector: RI

Commercially available products can be used as the polycarbonate diol used in the synthesis of the reaction product (C). Examples of commercially available products include T-5650J (diol components: 1,6-hexanediol and 1,5-pentanediol) and T-4671 (diol components: 1,6-hexanediol and 1,6 manufactured by Asahi Kasei Chemicals Corporation). 4-butanediol); UM-90 (diol components: 1,6-hexanediol and 1,4-cyclohexanedimethanol) manufactured by Ube Industries, Ltd.

Examples of the alkoxysilane compound used for the synthesis of the reaction product (C) include dialkoxysilane, trialkoxysilane, tetraalkoxysilane, isocyanate group-containing trialkoxysilane, and alkoxysilane oligomer.
Dialkoxysilanes include dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldiethoxysilane; trialkoxysilanes include methyltrimethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, and phenyltrimethoxy. Examples thereof include silane, methyltriethoxysilane, hexyltriethoxysilane, decyltriethoxysilane, and phenyltriethoxysilane.
Isocyanate group-containing trialkoxysilanes are γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane, γ-isocyanatopropyltributoxysilane; tetraalkoxysilanes are tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane And tetrabutoxysilane.

Of these, γ-isocyanatopropyltriethoxysilane can be preferably used from the viewpoints of finish and scratch resistance of the coating film.

These alkoxylane compounds can be used alone or in appropriate combination of two or more as required.

The reaction product (C) is usually synthesized under conditions such that a compound having a structure in which the end of the polycarbonate diol is modified with an alkoxysilane compound is obtained.

The optimum reaction temperature varies depending on the alkoxysilane compound used, but is about 100 to 150 ° C., for example, when methyltrimethoxylane is used as the alkoxysilane compound.

The polycarbonate diol and the alkoxylane compound can be synthesized by a condensation reaction under the condition that the equivalent ratio (alkoxy group of alkoxysilane compound / hydroxyl group of polycarbonate diol) is 5.0 or less. The relevant amount ratio is preferably 2.0 to 4.0, more preferably 2.3 to 3. from the viewpoints of curability when used as a coating composition, acid resistance and stain resistance of the resulting coating film, and the like. 5, more preferably 2.5 to 3.0.

The lower the corresponding ratio, the more the reaction product (C) having a higher proportion of the compound having a structure in which only one end of the polycarbonate diol is modified with an alkoxysilane compound. The higher the corresponding ratio, the more the both ends of the polycarbonate diol are. A reaction product (C) having a high production ratio of the compound having a structure modified with the alkoxysilane compound is obtained.

In addition, unreacted polycarbonate diol remains in the reaction product (C) as the amount ratio decreases, but in the present invention, the remaining polycarbonate diol is usually separated without separating the unreacted polycarbonate diol. The contained reaction product (C) can be used.

Among the above alkoxysilane compounds, in particular, when an isocyanate group-containing trialkoxysilane is used, the reaction product (C) is obtained by preferentially reacting the isocyanate group of the isocyanate group-containing trialkoxysilane with the hydroxyl group of the polycarbonate diol. Can be synthesized.

The reaction temperature is, for example, about 60 to 100 ° C. when γ-isocyanatopropyltriethoxysilane is used as the isocyanate group-containing trialkoxysilane.

The polycarbonate diol and the isocyanate group-containing trialkoxylane can be synthesized by urethanization under the condition that the equivalent ratio (isocyanate group of the isocyanate group-containing trialkoxylane / hydroxyl group of the polycarbonate diol) is 1.05 or less. The relevant amount ratio is preferably 0.85 to 1.03, more preferably 0.9 to 1.1, from the viewpoints of curability when used as a coating composition, acid resistance and stain resistance of the resulting coating film, and the like. 02, more preferably 0.95 to 1.00.

The lower the corresponding ratio, the more the reaction product (C) having a higher proportion of the compound having a structure in which only one end of the polycarbonate diol is modified with an alkoxysilane compound. The higher the corresponding ratio, the more the both ends of the polycarbonate diol are. A reaction product (C) having a high production ratio of the compound having a structure modified with the alkoxysilane compound is obtained.

In addition, unreacted polycarbonate diol remains in the reaction product (C) as the amount ratio decreases, but in the present invention, the remaining polycarbonate diol is usually separated without separating the unreacted polycarbonate diol. The contained reaction product (C) can be used.

The hydroxyl value of the reaction product (C) is 0 to 50 mgKOH / g, preferably 0 to 40 mgKOH / g, more preferably in terms of curability when used as a coating composition and stain resistance of the resulting coating film. Is 0-30 mg KOH / g.

The number average molecular weight of the reaction product (C) is 500 to 500 in terms of compatibility with the hydroxyl group-containing resin (A) and the polyisocyanate compound (B), scratch resistance, hardness, weather resistance, and the like of the resulting coating film. 5000, preferably 600 to 3000, more preferably 700 to 1500.

In the present invention, the hydroxyl value and the number average molecular weight are values as a reaction product (C) including an unreacted residual polycarbonate diol.

In the coating composition of the present invention, the equivalent ratio of the hydroxyl group of the hydroxyl group-containing resin (A) and the reaction product (C) to the isocyanate group of the polyisocyanate compound (B) from the viewpoint of the curability of the coating film and scratch resistance. (NCO / OH) is preferably in the range of 0.5 to 2.0, more preferably 0.8 to 1.5.

The amount of the hydroxyl group-containing resin (A), polyisocyanate compound (B) and reaction product (C) in the coating composition of the present invention is the total solid content of the component (A), the component (B) and the component (C). Based on 100 parts by mass, the non-volatile content of the hydroxyl group-containing resin (A) is 30 to 75% by mass, preferably 40 to 65% by mass, and the polyisocyanate compound (B) is 20 to 65% by mass, preferably 30 to 55%. It is suitable that the mass% and the reaction product (C) are in the range of 3 to 30 mass%, preferably 5 to 25 mass%, more preferably 10 to 20 mass%.

Other components This coating composition is a coating composition containing the hydroxyl group-containing resin (A), polyisocyanate compound (B), and reaction product (C) as essential components, and usually contains an organic solvent and is further necessary. Depending on the type, other curing catalysts, pigments, pigment dispersants, leveling agents, UV absorbers, light stabilizers, plasticizers, surface conditioners, etc. Can do.

Examples of the curing catalyst include tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, and dioctyl. Examples thereof include organometallic catalysts such as tin oxide and lead 2-ethylhexanoate, and tertiary amines.

These compounds described above as the curing catalyst may be used alone or as a mixture of two or more. The amount of the curing catalyst varies depending on the type, but is usually 5 parts by mass or less, preferably 0.1 to 4 parts by mass with respect to 100 parts by mass of the total solid content of the components (A), (B) and (C). About a part.

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, and perylene. Color pigments (D) such as pigments; body pigments such as talc, clay, kaolin, barita, barium sulfate, barium carbonate, calcium carbonate, silica, alumina white; aluminum powder, mica powder, mica powder coated with titanium oxide, etc. A metallic pigment etc. can be mention | raise | lifted.

These pigments described above can be used alone or in combination of two or more. The pigment content varies depending on the type, but is usually 200 parts by mass or less, preferably about 1 to 100 parts by mass with respect to 100 parts by mass of the total solid content of the components (A), (B) and (C). It is.

Further, although the content of the color pigment varies depending on the kind thereof, it is usually 150 parts by mass or less, preferably 1 to 100 parts per 100 parts by mass in total of the solid contents of the components (A), (B) and (C). About mass parts.

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.

The content of the ultraviolet absorber in the coating composition is usually 10 parts by mass or less, particularly 0.2 to 5 parts by mass, more particularly 0.3 to 2 parts by mass with respect to 100 parts by mass of the total resin solid content. It is preferable from the viewpoint of weather resistance and yellowing resistance.

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

The content of the light stabilizer in the coating composition is usually 0 to 10 parts by weight, particularly 0.2 to 5 parts by weight, more particularly 0.3 to 2 parts by weight with respect to 100 parts by weight of the total resin solid content. It is preferable from the viewpoint of weather resistance and yellowing resistance to be within the range of parts.

When the isocyanate group of the polyisocyanate compound as the component (B) is not blocked, the coating composition of the present invention has a hydroxyl group-containing resin (A) and a reaction product (C) because of storage stability. And the polyisocyanate compound (B) are separated from each other, and it is preferable to use a mixture of the two immediately before use.

Coating Method of Coating Composition The coating object to which the present coating is applied is not particularly limited, but is preferably the body of various vehicles such as automobiles, motorcycles, containers, and the like. In addition, cold rolled steel sheets, galvanized steel sheets, zinc alloy plated steel sheets, stainless steel sheets, tin plated steel sheets, etc., metal substrates such as aluminum plates, aluminum alloy plates, etc .; Good.

Further, the object to be coated may be one in which the metal surface of the vehicle body or metal substrate is subjected to a surface treatment such as a phosphate treatment, a chromate treatment, or a complex oxide treatment. Furthermore, as the object to be coated, an undercoat film and / or an intermediate coat film such as various electrodeposition paints may be formed on the vehicle body, metal base material, or the like.

The coating method of this paint is not particularly limited, and for example, a wet coating film can be formed by a coating method such as air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, or the like. In these coating methods, electrostatic application may be performed as necessary. Of these, air spray coating is particularly preferred. In general, the coating amount of the paint is preferably about 10 to 50 μm as a cured film thickness.

In the case of air spray coating, airless spray coating, and rotary atomization coating, the viscosity of the coating is adjusted to a viscosity range suitable for the coating, usually Ford Cup No. In a 4-viscosity meter, it is preferable to adjust appropriately using a solvent such as an organic solvent so that a viscosity range of about 15 to 60 seconds at 20 ° C. is obtained.

Curing of the wet coating film formed by applying the coating material to the object to be coated is performed by heating, and the heating can be performed by a known heating means, such as a hot air furnace, an electric furnace, an infrared induction heating furnace, etc. The drying oven can be applied. The heating temperature is suitably in the range of 60 to 180 ° C, preferably 90 to 150 ° C. The heating time is not particularly limited, but is preferably in the range of 15 to 30 minutes.

This paint can be used suitably as a top-coat top clear coat because it can provide a cured coating film excellent in any of scratch resistance, acid resistance, stain resistance and finish. This paint can be particularly suitably used as an automobile paint.

As a multi-layer coating film forming method in which this paint is applied as a top-coat top clear coat paint, at least one layer of a colored base coat paint and at least one layer of a clear coat paint are sequentially applied to an object to be coated. Thus, there can be mentioned a method for forming a multilayer coating film, wherein the coating composition of the present invention is applied as the uppermost clear coating composition.

Specifically, for example, a solvent-type or water-based base coat paint is applied on an object to which electrodeposition coating and / or intermediate coating has been applied, and the coating film is not cured, as needed. In order to promote the volatilization of the solvent in the base coat paint, for example, after preheating at 40 to 90 ° C. for about 3 to 30 minutes, this paint is applied as a clear coat paint on the uncured base coat film. Thereafter, there can be mentioned a method for forming a multi-layer coating film of a 2-coat 1-bake method in which the base coat and the clear coat are cured together.

Also, it can be suitably used as a top clear coat paint in the top coat of the 3-coat 2-bake method or the 3-coat 1-bake method.

As the base coat paint used in the above, a conventionally known normal thermosetting base coat paint can be used. Specifically, for example, a base resin such as an acrylic resin, a polyester resin, an alkyd resin, a urethane resin type, or the like. In addition, a coating material obtained by appropriately combining a curing agent such as an amino resin, a polyisocyanate compound, or a block polyisocyanate compound with a reactive functional group contained in the base resin can be used.

Also, as the base coat paint, a high solid type with a small amount of organic solvent used is desirable from the viewpoint of environmental problems, resource saving, etc. Further, a water-based paint or a powder paint can be used.

In the multilayer coating film forming method, when two or more clear coats are applied, a conventionally known normal thermosetting clear coat paint can be used as the clear coat paint in addition to the present paint.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples. In the following, “part” and “%” are both based on mass, and the film thickness of the coating film is based on the cured coating film.

Production Examples of Hydroxyl-Containing Resin (A) Production Examples 1 to 9
In a four-necked flask equipped with a stirrer, a thermometer, a cooling tube and a nitrogen gas inlet, 31 parts of ethoxyethyl propionate was charged, and the temperature was raised to 155 ° C. under nitrogen gas flow. After reaching 155 ° C., the flow of nitrogen gas was stopped, and a dropping monomer mixture composed of a monomer and a polymerization initiator shown in Table 1 below was dropped over 4 hours. After aging at 155 ° C. for 2 hours while bubbling nitrogen gas, the mixture was cooled to 100 ° C. and diluted with 32.5 parts of butyl acetate to obtain a coating resin having a solid content of 60%. Table 1 below shows the mass solid content concentration (%) and the resin property values of the obtained coating resin.

The measurement of the hydroxyl value in Table 1 was performed according to JISK-0070 (1992). Specifically, 5 ml of acetylating reagent (acetic anhydride pyridine solution adjusted to 100 ml by adding pyridine to 25 g of acetic anhydride) was added to the sample and heated in a glycerin bath, followed by potassium hydroxide solution Was titrated with phenolphthalein as an indicator, and calculated according to the following formula.
Hydroxyl value (mgKOH / g) = [V × 56.1 × C / m] + D
V: titration (ml), C: titrant concentration (mol / l), m: solid weight of sample (g), D: acid value of sample (mgKOH / g)

Here, the acid value was measured in accordance with JISK-5601-2-1 (1999). Specifically, the sample was dissolved in a mixed solvent of toluene / ethanol = 2/1 volume ratio, titrated with a potassium hydroxide solution using phenolphthalein as an indicator, and calculated according to the following formula.
Acid value (mgKOH / g) = 56.1 × V × C / m
V: titration volume (ml), C: concentration of titrant (mol / l), m: weight of solid content of sample (g)

The glass transition temperature (° C.) in Table 1 was calculated by the following formula.
1 / Tg (K) = (W1 / T1) + (W2 / T2) +
Tg (° C.) = Tg (K) -273
In each formula, W1, W2,... Represent the respective mass fractions of the monomers used for copolymerization, and T1, T2,... Represent the Tg (K) of the homopolymer of each monomer. T1, T2,... Are values according to Polymer Handbook (Second Edition, edited by J. Brandup, E. H. Immergut).

Production Examples of Reaction Products (C) Having Alkoxysilyl Groups Production Examples 10-23
A four-necked flask equipped with a stirrer, a thermometer, a cooling pipe and a nitrogen gas inlet is charged with the polycarbonate diol and swazol 1000 (trade name, hydrocarbon solvent manufactured by Cosmo Oil Co., Ltd.) shown in Table 2 below, and nitrogen The temperature was raised to the temperature (reaction temperature) shown in Table 2 below under the atmosphere. After reaching a predetermined temperature, an alkoxysilane compound shown in Table 2 below was added and reacted for 5 hours, whereby each reaction product (C) solution No. 1-14 were obtained. The mass solid content concentration (%) and the characteristic value of each reaction product solution obtained are also shown in Table 2 below. For the hydroxyl value, 1> indicates that the hydroxyl value is less than 1.

(* 1) to (* 6) in Table 2 have the following meanings, respectively, and the viscosity of the polycarbonate diol is 50 ° C. and is 6 rpm using a B-type viscometer (rotor number: No. 4). It is the value measured by.
(* 1) T-5650J: manufactured by Asahi Kasei Chemicals, polycarbonate diol having 1,6-hexanediol and 1,5-pentanediol as diol components, number average molecular weight 800, viscosity 860 mPa · s, hydroxyl value 140 mgKOH / g, 100% solids.
(* 2) T-4671: manufactured by Asahi Kasei Chemicals, polycarbonate diol having 1,6-hexanediol and 1,4-butanediol as diol components, number average molecular weight 1000, viscosity 2400 mPa · s, hydroxyl value 112 mgKOH / g, 100% solids.
(* 3) UM-90: manufactured by Ube Industries, Ltd., polycarbonate diol containing 1,6-hexanediol and 1,4-cyclohexanedimethanol as diol components, number average molecular weight 900, viscosity 7000 mPa · s, hydroxyl value 124 mgKOH / g , 100% solids.
(* 4) PC-M: polycarbonate diol synthesized using 1,6-hexanediol and 3-methylpentanediol as diol components, diphenyl carbonate as carbonylating agent, number average molecular weight 2000, viscosity 7000 mPa · s, hydroxyl value 56 mg KOH / g, 100% solids.
(* 5) PC-N: Polycarbonate diol synthesized using 1,6-hexanediol and 3-methylpentanediol as diol components, diphenyl carbonate as carbonylating agent, number average molecular weight 380, viscosity 120 mPa · s, hydroxyl value 260 mg KOH / g, solid content 100%.
(* 6) KR510: manufactured by Shin-Etsu Chemical Co., Ltd., methyl / phenyl type alkoxysilane oligomer

The numerical value about the compounding quantity of each polycarbonate diol and an alkoxysilane compound in Table 2 shows a mass part.

Production Examples 1-15 of the coating composition and Comparative Examples 1-9
Using the compounds obtained in the above production examples, the resin, and the raw materials listed in Table 3 below, the mixture shown in Table 3 below was stirred and mixed using a disper to form a paint, and each coating composition No. 1-24 were obtained. In addition, the mixing | blending of the coating composition shown in Table 3 is solid content mass ratio of each component. (* 7) to (* 10) in Table 3 have the following meanings, respectively.
(* 7) N-3300: manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanate, solid content 100%, NCO content 21.8%.
(* 8) UV1164: UV absorber manufactured by Ciba Geigy.
(* 9) HALS292: Ciba Geigy Corporation light stabilizer.
(* 10) BYK-300: trade name, manufactured by Big Chemie, surface conditioner.

Each coating composition No. obtained in Examples 1 to 15 and Comparative Examples 1 to 9 above. For Nos. 1 to 24, Ford Cup #No. 4 was adjusted to a viscosity of 25 seconds at 20 ° C.

Preparation of test plates Each coating composition No. obtained in Examples 1 to 15 and Comparative Examples 1 to 9 was used. Test plates were prepared in the following manner for each of those having a viscosity adjusted from 1 to 24.

Electron GT-10 (trade name, thermosetting epoxy resin-based cationic electrodeposition paint manufactured by Kansai Paint Co., Ltd.) has a thickness of 20 μm on a 0.8 mm-thick dull steel sheet subjected to zinc phosphate conversion treatment. Electrodeposited and heated at 170 ° C. for 30 minutes to cure, and then Amirac TP-65-2 (trade name, polyester / melamine resin-based automotive intermediate coating) manufactured by Kansai Paint Co., Ltd. with a film thickness of 35 μm Air spray coating was performed, and the mixture was heated and cured at 140 ° C. for 30 minutes. An aqueous metallic base coat WBC713T # 202 (manufactured by Kansai Paint Co., Ltd., acrylic / melamine resin-based automotive top coat paint, black paint color) is applied to the coating film so as to have a film thickness of 15 μm, and left at room temperature for 5 minutes. Then, after preheating at 80 ° C. for 10 minutes, each coating composition prepared and viscosity-adjusted in the above Examples and Comparative Examples was applied on the uncured coating film so as to have a film thickness of 35 μm. And then left at 10 ° C. for 10 minutes and then heated at 140 ° C. for 20 minutes to cure both coatings together to obtain a test plate. Each of the obtained test plates was allowed to stand at room temperature for 7 days and then subjected to the following coating film performance test.

Results of performance test : Scratch resistance: 20 degrees of test plate after car washer was washed 15 times with car wash machine at 20 ° C ± 5 ° C under the condition of 20 ° C ± 5 ° C. The specular reflectance (20 ° gloss value) was measured and evaluated by the gloss retention (%) relative to the 20 ° gloss value before the test. The higher the gloss retention, the better the scuff resistance, and usually 85% or more is required for use as a paint to be applied to automobile bodies and the like. As the car washer, “PO20 FWRC” manufactured by Yasui Industry Co., Ltd. was used.

Acid resistance: 0.4 cc of 40% sulfuric acid was dropped on the coating film of each test plate, heated for 15 minutes on a hot plate heated to 60 ° C., and then the test plate was washed with water. The etching depth (μm) of the sulfuric acid dripping site was cut off with a surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd., surface roughness shape measuring instrument “Surfcom 570A”) 0.8 mm (scanning speed 0.3 mm / sec The acid resistance was evaluated by measurement under the condition of 5000 times magnification. The smaller the etching depth, the better the acid resistance. Usually, it is required to be 0.6 μm or less in order to be used as a paint to be painted on an automobile body or the like.

Finishability (gloss): The 20-degree specular reflectance (20 ° gloss value) of the test plate was measured and evaluated. The higher the reflectance, the better the finish, and it is usually required to be 83 or more in order to be used as a paint to be painted on an automobile body or the like.

Contamination resistance: After each test coating plate was tested for 600 hours in a sunshine weatherometer (manufactured by Suga Test Instruments Co., Ltd., accelerated weathering tester), each test coating plate was contaminated with a mixture of mud, carbon black, mineral oil and clay. The substance was adhered to the nell and rubbed lightly on the surface of each test plate. This was left for 24 hours in a constant temperature and humidity chamber at 20 ° C. and 75% RH, and then the coated surface was washed with running water, and the degree of contamination of the coated film was evaluated according to the following criteria based on the lightness difference (ΔL) of the coated plate. The smaller the ΔL value, the better the stain resistance. ΔL was determined by the following equation.
ΔL = (L value before stain resistance test) − (L value after stain resistance test)
The L value was measured using CR-200 (color difference meter manufactured by Minolta Camera Co.).
A: ΔL <0.2, O: 0.2 ≦ ΔL <1, Δ: 1 ≦ ΔL <2, X: 2 ≦ ΔL.

In the contamination resistance test, Eleclon GT-10 (trade name, thermosetting epoxy resin-based cationic battery manufactured by Kansai Paint Co., Ltd.) was applied on a 0.8 mm-thick dull steel plate subjected to zinc phosphate conversion treatment. Electrodeposition coating) to a film thickness of 20 μm, cured by heating at 170 ° C. for 30 minutes, and then Amirac TP-65-2 (manufactured by Kansai Paint Co., Ltd., trade name, polyester / melamine resin system) Each of the above-mentioned Examples and Comparative Examples was prepared and viscosity-adjusted on a coating film that was air-sprayed to a film thickness of 35 μm and cured by heating at 140 ° C. for 30 minutes. Using the test plate obtained by coating the coating composition so as to have a film thickness of 35 μm, allowing it to stand at room temperature for 10 minutes, and then heating and curing at 140 ° C. for 20 minutes, each test plate was similarly used. At room temperature It was performed stain resistance test from left to days.
The performance test results are also shown in Table 3.

As shown in Table 3 above, the coating composition No. Nos. 1 to 15 (Examples 1 to 15) have all of high scratch resistance, acid resistance, stain resistance and finish of the coating film. In contrast, the coating composition No. 16-24 are significantly inferior in any of these characteristics.

Claims (8)

A hydroxyl group-containing resin (A) having a hydroxyl value of 80 to 200 mgKOH / g and a weight average molecular weight of 2500 to 40,000, a polyisocyanate compound (B), and an alkoxysilyl group obtained by a reaction between a polycarbonate diol and an alkoxysilane compound A coating composition comprising a reaction product (C) having a hydroxyl value of 0 to 50 mgKOH / g and a number average molecular weight of 500 to 5000. The coating composition according to claim 1, wherein the hydroxyl group-containing resin (A) is a hydroxyl group-containing acrylic resin. The coating composition according to claim 1, wherein the polyisocyanate compound (B) contains an aliphatic diisocyanate or a derivative thereof. The coating composition according to claim 1, wherein the reaction product (C) is obtained by a reaction between a polycarbonate diol and an isocyanate group-containing alkoxysilane compound. The coating composition according to claim 1, wherein the reaction product (C) is obtained by a reaction between a polycarbonate diol and a trialkoxysilane compound. Furthermore, the coating composition of Claim 1 containing a coloring pigment. 2. A method of forming a multilayer coating film by applying at least one layer of a colored base coat paint and at least one layer of a clear coat paint sequentially to an object, wherein the clear coat paint is the uppermost layer. A method for forming a multilayer coating film, comprising coating a coating composition. A coated article obtained by the multilayer coating film forming method according to claim 7.