Coating composition and in-mold coating method

Abstract

The present disclosure provides a coating composition which is capable of forming a coating film that is excellent in terms of contamination resistance, recovery from scratches, and smoothness, and which has a low VOC content.　The present disclosure relates to a coating composition which contains an isocyanate-reactive group-containing compound (A) and a polyisocyanate composition (B), and has a solid content concentration of 90 mass% or more, wherein: the polyisocyanate composition (B) has a uretdione group and an allophanate group; the molar ratio of the uretdione group to the total of the uretdione group and the allophanate group in the polyisocyanate composition (B) and one or more groups among an isocyanurate group, a urethane group, a biuret group, and an iminooxadiazinedione group, which are present in the polyisocyanate composition (B) is within the range of 5-25%; and the molar ratio of the allophanate group to the total of the uretdione group and the allophanate group in the polyisocyanate composition (B) and the one or more groups among the isocyanurate group, the urethane group, the biuret group, and the iminooxadiazinedione group, which are present in the polyisocyanate composition (B) is within the range of 5-55%.

Description

Coating composition and in-mold coating method

[0001] The present invention relates to a coating composition and an in-mold coating method.

[0002] Conventionally, for the purpose of imparting excellent appearance, performance, etc. to a substrate surface, a coating film has been formed by applying a coating composition to the substrate surface and curing the formed wet coating film. In recent years, from the viewpoint of reducing the environmental load, there has been a demand for reducing volatile organic compounds (VOCs) in coating compositions and reducing the air conditioning energy required during painting.

[0003] Furthermore, in recent years, in various technical fields, there has been a demand for high adhesion between the coating film and the substrate, in particular adhesion after a water load (water-resistant adhesion), as well as high hardness on the coated surface of the substrate. Furthermore, when the coating composition is applied to an article to be used outdoors, it is usually required to be able to form a coating film with high weather resistance.

[0004] Patent Document 1 discloses a two-component coating material composition comprising a paint base component A and a curing component B, wherein the paint base component A comprises: i. one or more polyols A1 selected from the group of polyols containing ester groups, and having a hydroxyl value of 300 to 500 mg KOH / g and a hydroxyl group functionality of more than 2; ii. one or more polyols A1 selected from the group of polyols containing ester groups, and having a hydroxyl value of 300 to 500 mg KOH / g and a hydroxyl group functionality of more than 2; １ -(OH) ｐ (In the formula, R １ is a p-valent branched, cyclic or straight-chain, saturated or unsaturated aliphatic hydrocarbon radical having 5 to 18 carbon atoms, and the radical R １ optionally containing one or more tertiary amino groups, and p is 2 to 6), iii. one or more aliphatic polyols A2 of the general formula (II): R ２ -(C=O) ｒ -O-(AO) ｓ -R ３ (In the formula, R ２ is a saturated or unsaturated aliphatic hydrocarbon radical having 6 to 30 carbon atoms, R ３ is H, radical PO(OH) ２or a radical of an optionally partially phosphorylated mono- or disaccharide or a radical of an optionally partially phosphorylated alditol, where AO represents one or more alkylene oxide radicals selected from the group consisting of ethylene oxide, propylene oxide, and butylene oxide, r is 0 or 1, and s is 0 to 30), iv. one or more crosslinking catalysts A4 selected from the group of organotin compounds, v. one or more polyamines A5 having at least two secondary amino groups and an amine value of 120 to 280 mg KOH / g, and ix. one or more additives A9 selected from the group consisting of wetting agents and / or dispersants, rheological aids, and flow control agents, and wherein said curing component B comprises: i. The two-component coating material composition is described as comprising one or more polyisocyanates B1 having an average of 2.4 to 5 NCO groups, the two-component coating material composition having a solids content of at least 96% by weight according to ASTM D2369 (2015), based on the total weight of the two-component coating material composition, and characterized in that the molar ratio of NCO groups in the curing component B to the acidic hydrogen atoms of hydroxyl groups, primary amino groups and secondary amino groups in the paint base component A is from 1:1.15 to 1:0.95, allowing damage-free release from normally metal mold surfaces without the use of external mold release agents, while ensuring very good adhesion to the substrate and allowing recoating with further coating films, such as base coats and clear coats, to form surfaces of very good quality without costly and inconvenient cleaning and / or polishing steps.

[0005] Special Publication No. 2020-528103

[0006] The technology described in Patent Document 1 results in a low VOC content in the resulting coating composition, but the resulting coating film may not have sufficient stain resistance, scratch recovery, and smoothness. An object of the present invention is to provide a coating composition that can form a coating film with excellent stain resistance, scratch recovery, and smoothness, and that has a low VOC content.

[0007] As a result of extensive research into achieving the above object, the present inventors have discovered a coating composition comprising an isocyanate-reactive group-containing compound (A) and a polyisocyanate composition (B), and having a solids concentration of 90 mass % or more, wherein the polyisocyanate composition (B) has uretdione groups and allophanate groups, and the uretdione groups and allophanate groups in the polyisocyanate composition (B) are in a ratio of 0.01 to 0.01, and the ratio of the isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups in the polyisocyanate composition (B) is in a ratio of 0.01 to 0.01. and the molar ratio of the allophanate groups to the total of the uretdione groups and allophanate groups in the polyisocyanate composition (B), and the isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups present in the polyisocyanate composition (B), is within the range of 5 to 55%.

[0008] That is, the present invention relates to the following items <1> to <7>: <1> A coating composition comprising an isocyanate-reactive group-containing compound (A) and a polyisocyanate composition (B) and having a solids concentration of 90 mass % or more, wherein the polyisocyanate composition (B) has uretdione groups and allophanate groups, and the molar ratio of the uretdione groups to the total of the uretdione groups and allophanate groups in the polyisocyanate composition (B) and the isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups present in the polyisocyanate composition (B) is within the range of 5 to 25%; a molar ratio of the allophanate groups to the total of the uretdione groups and allophanate groups in the polyisocyanate composition (B), and the isocyanurate groups, the urethane groups, the biuret groups, and the iminooxadiazinedione groups present in the polyisocyanate composition (B), is within the range of 5 to 55%.

[0009] <2> The coating composition according to <1>, wherein the isocyanate-reactive group-containing compound (A) comprises an isocyanate-reactive group-containing compound having two isocyanate-reactive groups. <3> The coating composition according to <1> or <2>, wherein the isocyanate-reactive group-containing compound (A) comprises an isocyanate-reactive group-containing compound having a number average molecular weight in the range of 300 to 1,000.

[0010] <4> The coating composition according to any one of <1> to <3>, wherein the isocyanate-reactive group-containing compound (A) comprises an isocyanate-reactive group-containing compound having an alicyclic skeleton. <5> The coating composition according to any one of <1> to <4>, further comprising a carbodiimide group-containing compound (C).

[0011] <6> An in-mold coating method comprising the steps of injecting an in-mold coating paint composition between a molded substrate and an inner wall of a mold, curing the in-mold coating paint composition, and then removing the coated molded article from the mold, wherein the in-mold coating paint composition is the paint composition described in any one of <1> to <5>. <7> The in-mold coating method described in <6>, wherein the film thickness of a coating film formed by the in-mold coating composition is within the range of 70 to 1000 μm in dry film thickness.

[0012] According to the present invention, it is possible to provide a coating composition that is capable of forming a coating film that is excellent in stain resistance, scratch recovery, and smoothness, and that has a low VOC content.

[0013] The present invention will be described in detail below, but these are examples of preferred embodiments, and the present invention is not limited to these details.

[0014] [Paint composition] The paint composition of the present invention comprises an isocyanate-reactive group-containing compound (A) and a polyisocyanate composition (B), and has a solids concentration of 90 mass % or more, wherein the polyisocyanate composition (B) has uretdione groups and allophanate groups, and the uretdione groups and allophanate groups in the polyisocyanate composition (B) and the isocyanurate groups, urethane groups, biuret groups and iminooxadiazinedione groups in the polyisocyanate composition (B) are the most preferable. The molar ratio of the uretdione groups to the total of those present in polyisocyanate composition (B) is within the range of 5 to 25%, and the molar ratio of the allophanate groups to the total of the uretdione groups and allophanate groups in polyisocyanate composition (B) and the isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups present in polyisocyanate composition (B) is within the range of 5 to 55%. In this specification, "solid content" refers to non-volatile components such as resins, curing agents, and pigments remaining after drying at 80°C for 30 minutes. The solid content can be determined, for example, by weighing a sample into a heat-resistant container such as an aluminum foil cup, spreading the sample on the bottom of the container, drying at 80°C for 30 minutes, and weighing the mass of the components remaining after drying.

[0015] In addition, in this specification, "solid content concentration" means the mass ratio of the above solid content in the composition. Therefore, the solid content concentration of the composition can be calculated by, for example, weighing 1.0 g of the composition into a heat-resistant container such as an aluminum foil cup, spreading the composition on the bottom of the container, drying at 80°C for 30 minutes, weighing the mass of the components in the composition remaining after drying, and determining the mass ratio of the components remaining after drying to the total mass of the composition before drying. The solid content concentration in the coating composition of the present invention is 90 mass% or more. By having a solid content concentration of the coating composition of 90 mass% or more, the VOC content in the resulting coating composition can be reduced.

[0016] The solids concentration of the coating composition of this embodiment is preferably in the range of 93 to 100 mass %, more preferably in the range of 95 to 100 mass %, and even more preferably in the range of 97 to 100 mass %, from the viewpoint of reducing the VOC content in the resulting coating composition.

[0017] [Isocyanate-reactive group-containing compound (A)] The isocyanate-reactive group-containing compound (A) is a compound having at least one isocyanate-reactive group per molecule. The isocyanate-reactive group is not particularly limited as long as it is a group that is reactive with an isocyanate group. Examples of the isocyanate-reactive group include a hydroxyl group, an amino group, a thiol group, etc., and from the viewpoint of the contamination resistance and scratch recovery properties of the coating film to be formed, it is preferable that the compound contains at least one selected from a hydroxyl group and an amino group, and more preferably contains a hydroxyl group.

[0018] Therefore, examples of the isocyanate-reactive group-containing compound (A) include a hydroxyl group-containing compound (A1), an amino group-containing compound (A2), a thiol group-containing compound (A3), a hydroxyl group- and amino group-containing compound, a hydroxyl group- and thiol group-containing compound, an amino group- and thiol group-containing compound, and an amino group-, hydroxyl group- and thiol group-containing compound. It is preferable that the compound contains at least one compound selected from the hydroxyl group-containing compound (A1) and the amino group-containing compound (A2), and it is more preferable that the compound contains the hydroxyl group-containing compound (A1).

[0019] The isocyanate-reactive group-containing compound (A) preferably contains two isocyanate-reactive group-containing compounds from the viewpoint of the scratch recovery properties of the coating film to be formed, etc. When the isocyanate-reactive group-containing compound (A) contains the two isocyanate-reactive group-containing compounds, the content of the two isocyanate-reactive group-containing compounds is preferably within the range of 10 to 100 mass%, more preferably within the range of 15 to 65 mass%, and even more preferably within the range of 25 to 60 mass%, based on the total solids content of the isocyanate-reactive group-containing compound (A), from the viewpoint of the contamination resistance and scratch recovery properties of the coating film to be formed, etc.

[0020] From the viewpoints of reducing the VOC content in the resulting coating composition and improving the contamination resistance, scratch recovery, smoothness, etc. of the coating film formed, the isocyanate-reactive group-containing compound (A) preferably contains an isocyanate-reactive group-containing compound having a number average molecular weight in the range of 300 to 1,000, more preferably contains an isocyanate-reactive group-containing compound having a number average molecular weight in the range of 400 to 850, and even more preferably contains an isocyanate-reactive group-containing compound having a number average molecular weight in the range of 450 to 600.

[0021] When the isocyanate-reactive group-containing compound (A) contains an isocyanate-reactive group-containing compound having a number average molecular weight in the range of 300 to 1000, the content of the isocyanate-reactive group-containing compound having a number average molecular weight in the range of 300 to 1000 is preferably in the range of 10 to 100 mass%, more preferably in the range of 25 to 100 mass%, and even more preferably in the range of 35 to 100 mass%, based on the total solids content of the isocyanate-reactive group-containing compound (A), from the viewpoint of reducing the VOC content in the resulting coating composition and improving the contamination resistance, scratch recovery, and smoothness of the coating film formed. From the viewpoint of the contamination resistance of the coating film formed, the isocyanate-reactive group-containing compound (A) preferably contains an isocyanate-reactive group-containing compound having an alicyclic skeleton.

[0022] When the isocyanate-reactive group-containing compound (A) contains an isocyanate-reactive group-containing compound having an alicyclic skeleton, the content of the isocyanate-reactive group-containing compound having an alicyclic skeleton is preferably in the range of 5 to 100 mass %, more preferably in the range of 10 to 100 mass %, and even more preferably in the range of 20 to 100 mass %, based on the total solids content of the isocyanate-reactive group-containing compound (A), from the viewpoints of the contamination resistance and scratch recovery properties of the coating film to be formed.

[0023] [Hydroxyl Group-Containing Compound (A1)] The hydroxyl group-containing compound (A1) is a compound having at least one hydroxyl group per molecule. Examples of the hydroxyl group-containing compound (A1) include hydroxyl group-containing oligomers and hydroxyl group-containing polymers, such as hydroxyl group-containing polyester resins, hydroxyl group-containing polycaprolactone resins, hydroxyl group-containing polyether resins, hydroxyl group-containing polycarbonate resins, hydroxyl group-containing acrylic resins, hydroxyl group-containing acrylic-modified polyester resins, hydroxyl group-containing polyurethane resins, hydroxyl group-containing epoxy resins, and hydroxyl group-containing alkyd resins. Among these, hydroxyl group-containing polyester resins are preferred from the viewpoints of reducing the VOC content in the resulting coating composition, as well as improving stain resistance, scratch recovery, and smoothness. These compounds can be used alone or in combination of two or more. The hydroxyl group-containing polyester resins can usually be produced by esterification or transesterification of an acid component and an alcohol component.

[0024] The acid component may be a compound typically used as a polycarboxylic acid in the production of the hydroxyl group-containing polyester resin. Examples of such polycarboxylic acids include aliphatic polybasic acids, alicyclic polybasic acids, and aromatic polybasic acids. When the acid component contains a polycarboxylic acid, the polycarboxylic acid preferably contains an alicyclic polybasic acid, from the viewpoint of the stain resistance of the coating film to be formed. The alicyclic polybasic acid is generally a compound having one or more alicyclic structures and two or more carboxyl groups per molecule, an acid anhydride of the compound, or an ester of the compound. The alicyclic structure may be primarily a 4- to 6-membered ring structure. Examples of alicyclic polybasic acids include alicyclic polycarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3-methyl-1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, and 1,3,5-cyclohexanetricarboxylic acid; anhydrides of these alicyclic polycarboxylic acids; and lower alkyl esters of these alicyclic polycarboxylic acids having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The above alicyclic polybasic acids can be used alone or in combination of two or more.

[0025] The aliphatic polybasic acid is generally an aliphatic compound having two or more carboxyl groups per molecule, an acid anhydride of the aliphatic compound, or an ester of the aliphatic compound. Examples of the aliphatic polybasic acid include aliphatic polycarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, octadecanedioic acid, citric acid, and butanetetracarboxylic acid; anhydrides of the aliphatic polybasic carboxylic acids; and lower alkyl esters of the aliphatic polybasic carboxylic acids having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The aliphatic polybasic acids can be used alone or in combination of two or more.

[0026] The aromatic polybasic acid is generally an aromatic compound having two or more carboxyl groups per molecule, an acid anhydride of the aromatic compound, or an ester of the aromatic compound. Examples of the aromatic polybasic acid include aromatic polycarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, trimellitic acid, and pyromellitic acid; anhydrides of the aromatic polycarboxylic acids; and lower alkyl esters of the aromatic polycarboxylic acids having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. The aromatic polybasic acids can be used alone or in combination of two or more.

[0027] Acid components other than the above-mentioned aliphatic polybasic acids, alicyclic polybasic acids, and aromatic polybasic acids can also be used. Such acid components are not particularly limited, and examples include fatty acids such as coconut oil fatty acids, cottonseed oil fatty acids, hempseed oil fatty acids, rice bran oil fatty acids, fish oil fatty acids, tall oil fatty acids, soybean oil fatty acids, linseed oil fatty acids, tung oil fatty acids, rapeseed oil fatty acids, castor oil fatty acids, dehydrated castor oil fatty acids, and safflower oil fatty acids; monocarboxylic acids such as isononanoic acid, neodecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexanoic acid, and 10-phenyloctadecanoic acid; and hydroxycarboxylic acids such as lactic acid, 3-hydroxybutanoic acid, and 3-hydroxy-4-ethoxybenzoic acid. These acid components can be used alone or in combination of two or more.

[0028] As the alcohol component, a polyhydric alcohol having two or more hydroxyl groups in one molecule can be suitably used. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1 ,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclohexane dihydric alcohols such as candimethanol, hydroxypivalic acid neopentyl glycol ester, hydrogenated bisphenol A, hydrogenated bisphenol F, and dimethylolpropionic acid; polylactone diols obtained by adding a lactone compound such as ε-caprolactone to these dihydric alcohols; ester diol compounds such as bis(hydroxyethyl) terephthalate; polyether diol compounds such as alkylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; trihydric or higher alcohols such as glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tris(2-hydroxyethyl)isocyanuric acid, sorbitol, and mannite; polylactone polyol compounds obtained by adding a lactone compound such as ε-caprolactone to these trihydric or higher alcohols; and fatty acid esters of glycerin.

[0029] When the alcohol component contains a polyhydric alcohol, the polyhydric alcohol preferably contains a polyhydric alcohol having an alicyclic skeleton, from the viewpoint of the stain resistance of the coating film to be formed, etc. Examples of the polyhydric alcohol having an alicyclic skeleton include 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 4,4-bicyclohexanol, 4-(2-hydroxyethyl)cyclohexanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,3-cyclopentanediol, tricyclodecane dimethanol, 1,3-adamantanediol, pentacyclopentadecanedimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol F.

[0030] Alcohol components other than the above polyhydric alcohols can also be used. Examples of such alcohol components include, but are not limited to, monoalcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, isobutyl alcohol, pentyl alcohol, 2-ethylhexyl alcohol, stearyl alcohol, benzyl alcohol, phenethyl alcohol, and 2-phenoxyethanol; and alcohol compounds obtained by reacting a monoepoxy compound such as propylene oxide, butylene oxide, or "Cardura E10P" (trade name, manufactured by Hexion, a glycidyl ester of synthetic highly branched saturated fatty acid) with an acid.

[0031] The method for producing the hydroxyl-containing polyester resin is not particularly limited and can be carried out according to a conventional method. For example, a hydroxyl-containing polyester polyol resin can be produced by heating the acid component and the alcohol component in a nitrogen stream at about 150 to 250°C for about 5 to 10 hours to carry out an esterification reaction or transesterification reaction between the acid component and the alcohol component. When carrying out the esterification reaction or transesterification reaction of the acid component and the alcohol component, these components may be added to a reaction vessel all at once, or one or both may be added in several portions. Alternatively, the hydroxyl-containing polyester resin may be first synthesized, and then the resulting hydroxyl-containing polyester resin may be reacted with an acid anhydride to half-esterify it into a carboxyl- and hydroxyl-containing polyester resin. Alternatively, a carboxyl-containing polyester resin may be first synthesized, and then the alcohol component may be added to produce the hydroxyl-containing polyester resin.

[0032] During the esterification or transesterification reaction, known catalysts such as dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, and tetraisopropyl titanate can be used as catalysts to promote the reaction. The hydroxyl-containing polyester resin can be modified with a fatty acid, a monoepoxy compound, a polyisocyanate compound, or the like during or after production of the resin. Examples of the fatty acid include coconut oil fatty acid, cottonseed oil fatty acid, hempseed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, dehydrated castor oil fatty acid, and safflower oil fatty acid. An example of the monoepoxy compound that can be suitably used is "Cardura E10P" (trade name, manufactured by Hexion, a glycidyl ester of a synthetic highly branched saturated fatty acid).

[0033] Examples of the polyisocyanate compound include aliphatic diisocyanate compounds such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; and alicyclic diisocyanate compounds such as hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,3-(isocyanatomethyl)cyclohexane, and 1,4-(isocyanatomethyl)cyclohexane. aromatic diisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenylmethane diisocyanate, etc.; organic polyisocyanates themselves, such as trivalent or higher polyisocyanates such as lysine triisocyanate, 4-(isocyanatomethyl)octamethylene diisocyanate, etc.; adducts of these organic polyisocyanates with polyhydric alcohols, low-molecular-weight polyester resins, water, etc.; cyclized polymers (for example, isocyanurates) and biuret-type adducts of these organic polyisocyanates. These polyisocyanate compounds can be used alone or in combination of two or more.

[0034] From the viewpoint of the scratch recovery of the coating film formed, the hydroxyl group-containing polyester resin preferably contains a hydroxyl group-containing polyester resin having two isocyanate-reactive groups. When the hydroxyl group-containing compound (A1) contains the hydroxyl group-containing polyester resin, from the viewpoints of reducing the VOC content in the resulting coating composition and of the stain resistance, scratch recovery, and smoothness of the coating film formed, the hydroxyl group-containing polyester resin preferably contains a hydroxyl group-containing polyester resin having a number average molecular weight in the range of 300 to 1,000, more preferably a hydroxyl group-containing polyester resin having a number average molecular weight in the range of 400 to 850, and even more preferably a hydroxyl group-containing polyester resin having a number average molecular weight in the range of 450 to 600. From the viewpoint of the stain resistance of the coating film formed, the hydroxyl group-containing polyester resin preferably contains a hydroxyl group-containing polyester resin having an alicyclic skeleton.

[0035] From the viewpoint of the contamination resistance and scratch recovery properties of the coating film to be formed, the hydroxyl value of the hydroxyl-containing polyester resin is preferably within a range of 20 to 600 mgKOH / g, more preferably within a range of 100 to 580 mgKOH / g, and even more preferably within a range of 300 to 560 mgKOH / g.

[0036] The glass transition temperature (Tg) of the hydroxyl group-containing polyester resin is preferably within the range of −80 to 10° C., more preferably within the range of −70 to 5° C., and even more preferably within the range of −60 to 0° C., from the viewpoints of the contamination resistance, scratch recovery, smoothness, etc. of the coating film to be formed.

[0037] In this specification, the number average molecular weight and weight average molecular weight are values ​​obtained by converting the retention time (retention volume) measured using a gel permeation chromatograph (GPC) into the molecular weight of polystyrene using the retention time (retention volume) of a standard polystyrene of known molecular weight measured under the same conditions. Specifically, the gel permeation chromatograph uses "HLC-8120GPC" (trade name, manufactured by Tosoh Corporation), four columns ("TSKgel G4000HXL", "TSKgel G3000HXL", "TSKgel G2500HXL", and "TSKgel G2000HXL" (trade names, all manufactured by Tosoh Corporation) in total, a differential refractometer is used as the detector, and the mobile phase is tetrahydrofuran, the measurement temperature is 40°C, and the flow rate is 1 mL / min.

[0038] The glass transition temperature can be measured, for example, using a differential scanning calorimeter "DSC-50Q" (Shimadzu Corporation, trade name), by placing a sample in a measuring cup, vacuum suctioning to completely remove the solvent, and then measuring the change in heat quantity at a temperature increase rate of 3°C / min in the range of -100°C to 150°C, and taking the first change in the baseline on the low-temperature side as the static glass transition temperature. When a hydroxyl-containing polyester resin is contained as the hydroxyl-containing compound (A1), the content of the hydroxyl-containing polyester resin is preferably in the range of 10 to 100% by mass, more preferably in the range of 20 to 100% by mass, and even more preferably in the range of 40 to 100% by mass, based on the total solids content of the hydroxyl-containing compound (A1), from the viewpoints of reducing the VOC content in the resulting coating composition and improving the stain resistance, scratch recovery, and smoothness of the coating film formed.

[0039] The hydroxyl group-containing polycaprolactone resin can be obtained, for example, by ring-opening polymerization of ε-caprolactone using a dihydric to tetrahydric polyhydric alcohol as an initiator. Examples of the dihydric or higher polyhydric alcohol include polyhydric alcohol compounds obtained by reacting ethylene glycol, glycerin, trimethylolethane, trimethylolpropane, diglycerin, ditrimethylolpropane, 1,2,6-hexanetriol, pentaerythritol, tris(2-hydroxyethyl)isocyanuric acid, or dimethylolalkanoic acid with a monoepoxy compound (e.g., "Cardura E10P; glycidyl ester of synthetic highly branched saturated fatty acid" manufactured by HEXION Specialty Chemicals). These can be used alone or in combination of two or more.

[0040] Commercially available hydroxyl group-containing polycaprolactone resins can be used, such as "PLACCEL 205," "PLACCEL 205H," "PLACCEL L205AL," "PLACCEL 205U," "PLACCEL 208," "PLACCEL 210," "PLACCEL 210N," "PLACCEL 210CP," "PLACCEL 212," "PLACCEL L212AL," "PLACCEL 220," "PLACCEL 220N," "PLACCEL 220CPB," "PLACCEL 220CPT," and "PLACCEL 2 20UA," "Placcel 220NP1," "Placcel L220AL," "Placcel 220EB," "Placcel 230," "Placcel 230N," "Placcel 240," "Placcel 303," "Placcel 305," "Placcel 308," "Placcel 309," "Placcel 312," "Placcel 320," "Placcel L320AL," "Placcel 410" (all trade names, manufactured by Daicel Corporation), "TONE Examples of the acrylic acid esters include Capa 0201, Capa 0230, Capa 0249, Capa 0301, Capa 0305, Capa 0310, Capa 1241, Capa 1278, and Capa 2221 (all trade names manufactured by The Dow Chemical Company), Capa 2043, Capa 2101, Capa 2201, Capa 2205, Capa 2209, Capa 2201A, Capa 2203A, Capa 3031, Capa 3050J, Capa 3091, and Capa 4101 (all trade names manufactured by Ingevity).

[0041] The hydroxyl group-containing polycaprolactone resin preferably contains a hydroxyl group-containing polycaprolactone resin having two hydroxyl groups from the viewpoint of the scratch recovery properties of the coating film to be formed, etc. As the hydroxyl group-containing polycaprolactone resin having two hydroxyl groups, a commercially available product can be used. Examples of trade names of commercially available products include "Placcel 205", "Placcel 205H", "Placcel L205AL", "Placcel 205U", "Placcel 208", "Placcel 210", "Placcel 210N", "Placcel 210CP", "Placcel 212", "Placcel L212AL", "Placcel 220", "Placcel 220N", "Placcel 220CPB", "Placcel 220CPT", "Placcel 220UA", "Placcel 220NP1", "Placcel L220AL", "Placcel 220EB", "Placcel 230", "Placcel 230N", and "Placcel 240" (all trade names, manufactured by Daicel Corporation), "TONE 0201", "TONE 0230", "TONE 0249", "TONE 1241", and "TONE Examples of suitable acrylic acid esters include "Capa 1278" and "TONE 2221" (all trade names, manufactured by The Dow Chemical Company), "Capa 2043," "Capa 2101," "Capa 2201," "Capa 2205," "Capa 2209," "Capa 2201A," and "Capa 2203A" (all trade names, manufactured by Ingevity). From the viewpoints of reducing the VOC content in the resulting coating composition and improving the contamination resistance, scratch recovery, smoothness, etc. of the coating film formed, the hydroxyl group-containing polycaprolactone resin preferably contains a hydroxyl group-containing polycaprolactone resin having a number average molecular weight in the range of 300 to 1,000, more preferably a hydroxyl group-containing polycaprolactone resin having a number average molecular weight in the range of 350 to 850, and even more preferably a hydroxyl group-containing polycaprolactone resin having a number average molecular weight in the range of 400 to 600.

[0042] The hydroxyl group-containing polycaprolactone resin preferably contains a hydroxyl group-containing polycaprolactone resin having an alicyclic skeleton, from the viewpoint of the stain resistance of the coating film to be formed, etc. The hydroxyl group value of the hydroxyl group-containing polycaprolactone resin is preferably within the range of 50 to 900 mgKOH / g, more preferably within the range of 100 to 750 mgKOH / g, and even more preferably within the range of 130 to 600 mgKOH / g, from the viewpoint of the stain resistance and scratch recovery of the coating film to be formed.

[0043] When the hydroxyl group-containing compound (A1) contains a hydroxyl group-containing polycaprolactone resin, the content of the hydroxyl group-containing polycaprolactone resin is preferably within a range of 10 to 80 mass%, more preferably within a range of 15 to 60 mass%, and even more preferably within a range of 20 to 40 mass%, based on the total solids content of the hydroxyl group-containing compound (A1), from the viewpoints of the stain resistance, scratch recovery, and smoothness of the coating film formed. Examples of the hydroxyl group-containing polyether resin include alkylene oxide adducts of hydroxyl group-containing monomers, and ring-opening (co)polymers of alkylene oxides or cyclic ethers (e.g., tetrahydrofuran), as described below. Specific examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene glycol-propylene glycol (block or random) copolymers, polyhexamethylene glycol, and polyoctamethylene glycol. The hydroxyl group-containing polyether resins can be used alone or in combination of two or more.

[0044] The hydroxyl-containing polyether resin preferably contains a hydroxyl-containing polyether resin having two hydroxyl groups, from the viewpoint of the scratch recovery properties of the coating film formed, etc. From the viewpoints of reducing the VOC content in the resulting coating composition and of the contamination resistance, scratch recovery properties, smoothness, etc. of the coating film formed, the hydroxyl-containing polyether resin preferably contains a hydroxyl-containing polyether resin having a number average molecular weight in the range of 300 to 1,000, more preferably a hydroxyl-containing polyether resin having a number average molecular weight in the range of 350 to 850, and even more preferably a hydroxyl-containing polyether resin having a number average molecular weight in the range of 400 to 60.

[0045] The hydroxyl value of the hydroxyl-containing polyether resin is preferably in the range of 50 to 600 mgKOH / g, more preferably in the range of 70 to 500 mgKOH / g, and even more preferably in the range of 90 to 400 mgKOH / g, from the viewpoint of the stain resistance and scratch recovery of the coating film formed. When a hydroxyl-containing polyether resin is contained as the hydroxyl-containing compound (A1), the content of the hydroxyl-containing polyether resin is preferably in the range of 5 to 100 mass%, more preferably in the range of 10 to 50 mass%, and even more preferably in the range of 10 to 25 mass%, based on the total solid content of the hydroxyl-containing compound (A1), from the viewpoint of reducing the VOC content in the resulting coating composition and the scratch recovery and smoothness of the coating film formed.

[0046] The hydroxyl group-containing polycarbonate resin is a compound obtained by a conventional polycondensation reaction of a known polyol component with a carbonylating agent. Examples of the polyol component include a diol component and a polyhydric alcohol component such as a trihydric or higher alcohol.

[0047] Examples of the diol component include linear diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-ethyl-1,6-hexanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,2, Examples of suitable diol components include branched diols such as 4-trimethyl-1,3-pentanediol and 2-ethyl-1,3-hexanediol; alicyclic diols such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; aromatic diols such as p-xylenediol and p-tetrachloroxylenediol; ether-based diols such as diethylene glycol and dipropylene glycol; and polylactone diols obtained by adding a lactone compound such as ε-caprolactone to any of these diol components. These diol components can be used alone or in combination of two or more. From the viewpoint of the stain resistance of the coating film to be formed, it is preferable that the diol component contains the above-mentioned alicyclic diol.

[0048] Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, a trimethylolpropane dimer, and pentaerythritol; and polylactone polyols obtained by adding a lactone compound such as ε-caprolactone to these trihydric or higher alcohols. These trihydric or higher alcohols can be used alone or in combination of two or more. Known carbonylating agents can be used. Specific examples include alkylene carbonate, dialkyl carbonate, diallyl carbonate, and phosgene, and these can be used alone or in combination of two or more. Among these, preferred examples include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, and diphenyl carbonate.

[0049] The hydroxyl group-containing polycarbonate resin preferably contains a hydroxyl group-containing polycarbonate resin having two hydroxyl groups, from the viewpoint of the scratch recovery properties of the coating film formed. From the viewpoints of reducing the VOC content in the resulting coating composition and of the stain resistance, scratch recovery properties, and smoothness of the coating film formed, the hydroxyl group-containing polycarbonate resin preferably contains a hydroxyl group-containing polycarbonate resin having a number average molecular weight in the range of 300 to 1,000, more preferably a hydroxyl group-containing polycarbonate resin having a number average molecular weight in the range of 400 to 850, and even more preferably a hydroxyl group-containing polycarbonate resin having a number average molecular weight in the range of 450 to 600. From the viewpoint of the stain resistance of the coating film formed, the hydroxyl group-containing polycarbonate resin preferably contains a hydroxyl group-containing polycarbonate resin having an alicyclic skeleton. From the viewpoint of the contamination resistance and scratch recovery of the coating film to be formed, the hydroxyl value of the hydroxyl-containing polycarbonate resin is preferably within a range of 50 to 600 mgKOH / g, more preferably within a range of 70 to 500 mgKOH / g, and even more preferably within a range of 90 to 400 mgKOH / g.

[0050] When the hydroxyl group-containing compound (A1) contains a hydroxyl group-containing polycarbonate resin, the content of the hydroxyl group-containing polycarbonate resin is preferably within the range of 10 to 100 mass%, more preferably within the range of 25 to 100 mass%, and even more preferably within the range of 40 to 100 mass%, based on the total solids content of the hydroxyl group-containing compound (A1), from the viewpoints of the contamination resistance, scratch recovery, and smoothness of the coating film formed. The hydroxyl group-containing acrylic resin can be produced, for example, by copolymerizing a hydroxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer by a method known per se, such as solution polymerization or emulsion polymerization in water. Production by solution polymerization is preferred. When the hydroxyl group-containing acrylic resin is produced by solution polymerization, the solution used in the solution polymerization preferably contains a polyhydric alcohol.

[0051] The hydroxyl group-containing polymerizable unsaturated monomer is a compound having one or more hydroxyl groups and one or more polymerizable unsaturated bonds per molecule. Examples of the hydroxyl group-containing polymerizable unsaturated monomer include monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; ε-caprolactone-modified monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms; N-hydroxymethyl (meth)acrylamide; allyl alcohol; and (meth)acrylates having a polyoxyethylene chain with a hydroxyl group at the molecular terminal. However, in this embodiment, a monomer corresponding to the polymerizable unsaturated monomer having an ultraviolet-absorbing functional group (xvii) described later should be defined as another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer, and is excluded from the hydroxyl group-containing polymerizable unsaturated monomer. These can be used alone or in combination of two or more kinds.

[0052] As other polymerizable unsaturated monomers copolymerizable with the above-mentioned hydroxyl group-containing polymerizable unsaturated monomers, for example, the following monomers (i) to (xx) can be used. These polymerizable unsaturated monomers can be used alone or in combination of two or more. (i) Alkyl or cycloalkyl (meth)acrylates: for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate, and the like. (ii) Polymerizable unsaturated monomers having an isobornyl group: isobornyl (meth)acrylate, etc.

[0053] (iii) Polymerizable unsaturated monomers having an adamantyl group: adamantyl (meth)acrylate, etc. (iv) Polymerizable unsaturated monomers having a tricyclodecenyl group: tricyclodecenyl (meth)acrylate, etc. (v) Polymerizable unsaturated monomers containing an aromatic ring: benzyl (meth)acrylate, styrene, α-methylstyrene, vinyltoluene, etc.

[0054] (vi) Polymerizable unsaturated monomers having an alkoxysilyl group: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, etc. (vii) Polymerizable unsaturated monomers having a fluorinated alkyl group: perfluoroalkyl(meth)acrylates such as perfluorobutylethyl(meth)acrylate and perfluorooctylethyl(meth)acrylate; fluoroolefins, etc. (viii) Polymerizable unsaturated monomers having a photopolymerizable functional group such as a maleimide group.

[0055] (ix) Vinyl compounds: N-vinylpyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate, etc. (x) Carboxyl group-containing polymerizable unsaturated monomers: (meth)acrylic acid, maleic acid, crotonic acid, β-carboxyethyl (meth)acrylate, etc. (xi) Nitrogen-containing polymerizable unsaturated monomers: (meth)acrylonitrile, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, methylenebis(meth)acrylamide, ethylenebis(meth)acrylamide, adducts of glycidyl (meth)acrylate and amine compounds, etc.

[0056] (xii) Polymerizable unsaturated monomers having two or more polymerizable unsaturated groups in one molecule: allyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, etc. (xiii) Epoxy group-containing polymerizable unsaturated monomers: glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, allyl glycidyl ether, etc. (xiv) (meth)acrylates having a polyoxyethylene chain with an alkoxy group at the molecular terminal.

[0057] (xv) Polymerizable unsaturated monomers having a sulfonic acid group: 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth)acrylate, allylsulfonic acid, 4-styrenesulfonic acid, etc.; sodium salts and ammonium salts of these sulfonic acids, etc. (xvi) Polymerizable unsaturated monomers having a phosphoric acid group: acid phosphooxyethyl (meth)acrylate, acid phosphooxypropyl (meth)acrylate, acid phosphooxypoly(oxyethylene)glycol (meth)acrylate, acid phosphooxypoly(oxypropylene)glycol (meth)acrylate, etc. (xvii) Polymerizable unsaturated monomers having an ultraviolet absorbing functional group: 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole, etc. (xviii) Light-stable polymerizable unsaturated monomers: 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and the like.

[0058] (xix) Polymerizable unsaturated monomers having a carbonyl group: acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrene, vinyl alkyl ketones having 4 to 7 carbon atoms (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone), etc. (xx) Polymerizable unsaturated monomers having an acid anhydride group: maleic anhydride, itaconic anhydride, citraconic anhydride, etc.

[0059] In this specification, the term "polymerizable unsaturated group" refers to an unsaturated group capable of radical polymerization. Examples of such polymerizable unsaturated groups include vinyl groups, (meth)acryloyl groups, (meth)acrylamide groups, vinyl ether groups, allyl groups, propenyl groups, isopropenyl groups, and maleimide groups. In this specification, "(meth)acrylate" refers to acrylate or methacrylate. "(meth)acrylic acid" refers to acrylic acid or methacrylic acid. "(meth)acryloyl" refers to acryloyl or methacryloyl. "(meth)acrylamide" refers to acrylamide or methacrylamide. From the viewpoint of the stain resistance of the coating film to be formed, it is preferable that the polymerizable unsaturated monomer contains a polymerizable unsaturated monomer having an alicyclic skeleton.

[0060] Examples of the polymerizable unsaturated monomer having an alicyclic skeleton include cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, tricyclodecanyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, tricyclodecenyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, etc. The polymerizable unsaturated monomer having an alicyclic skeleton can be used alone or in combination of two or more.

[0061] The hydroxyl group-containing acrylic resin preferably contains a hydroxyl group-containing acrylic resin having an alicyclic skeleton, from the viewpoint of the stain resistance of the coating film to be formed, etc. The hydroxyl group value of the hydroxyl group-containing acrylic resin is preferably within the range of 50 to 200 mgKOH / g, more preferably within the range of 70 to 190 mgKOH / g, and even more preferably within the range of 100 to 180 mgKOH / g, from the viewpoint of the stain resistance and scratch recovery of the coating film to be formed, etc.

[0062] The glass transition temperature (Tg) of the hydroxyl group-containing acrylic resin is preferably within the range of -20 to 70°C, more preferably within the range of -10 to 50°C, and even more preferably within the range of 0 to 40°C, from the viewpoints of reducing the VOC content in the resulting coating composition and improving the contamination resistance, scratch recovery, and smoothness of the coating film formed.

[0063] In this specification, the glass transition temperature (Tg) of the hydroxyl group-containing acrylic resin is a value calculated by the following formula: 1 / Tg(K) = W1 / T1 + W2 / T2 + ... Wn / Tn Tg(°C) = Tg(K) - 273 In the formula, W1, W2, ... Wn are the mass fractions of each monomer, and T1, T2, ... Tn are the glass transition temperatures Tg(K) of the homopolymers of each monomer. The glass transition temperatures of the homopolymers of each monomer are calculated by the ... The glass transition temperature of a monomer not described in the document is the static glass transition temperature when a homopolymer of the monomer is synthesized so as to have a weight-average molecular weight of about 50,000.

[0064] The polyhydric alcohol is a compound having two or more hydroxyl groups in one molecule. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2 -pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, tetramethylene glycol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, hydroxypivalate polylactone diols obtained by adding a lactone compound such as ε-caprolactone to any of these dihydric alcohols; ester diol compounds such as bis(hydroxyethyl) terephthalate; polyether diol compounds such as alkylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; trihydric or higher alcohols such as glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tris(2-hydroxyethyl)isocyanuric acid, sorbitol, and mannite; polylactone polyol compounds obtained by adding a lactone compound such as ε-caprolactone to any of these trihydric or higher alcohols; and fatty acid esters of glycerin.

[0065] The polyhydric alcohols can be used alone or in combination of two or more. From the viewpoint of reducing the VOC content in the resulting coating composition, the blending amount of the polyhydric alcohol is preferably within the range of 10 to 150 mass%, more preferably 20 to 130 mass%, and even more preferably 40 to 100 mass%, based on the total amount of the hydroxyl group-containing acrylic resin. The solution used in the solution polymerization method can contain an organic solvent other than the polyhydric alcohol, as necessary.

[0066] Examples of the organic solvent include aromatic solvents such as toluene, xylene, and "Swasol 1000" (trade name, high-boiling point petroleum solvent, manufactured by Cosmo Oil Co., Ltd.); ester solvents such as ethyl acetate, butyl acetate, propyl propionate, butyl propionate, 1-methoxy-2-propyl acetate, 2-ethoxyethyl propionate, 3-methoxybutyl acetate, 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; and alcohol solvents such as isopropanol, n-butanol, isobutanol, and 2-ethylhexanol.

[0067] When the hydroxyl group-containing compound (A1) contains the hydroxyl group-containing acrylic resin, the content of the hydroxyl group-containing acrylic resin is preferably in the range of 10 to 100 mass %, more preferably in the range of 25 to 90 mass %, and even more preferably in the range of 40 to 85 mass %, based on the total solid content of the hydroxyl group-containing compound (A1), from the viewpoints of the contamination resistance and scratch recovery properties of the coating film to be formed.

[0068] The hydroxyl group-containing compound (A1) may be, for example, ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,2-butanediol, 2 -butyl-2-ethyl-1,3-propanediol, 1,2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol ethanol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydroxypivalic acid neopentyl glycol ester, hydrogenated bisphenol A, hydrogenated bisphenol F, glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tris(2-hydroxyethyl)isocyanuric acid, sorbitol, mannite, hydroxyacetone, 4-(2-hydroxyethyl)morpholine, benzyl alcohol, 2-phenylethanol, 2-phenoxyethanol, naphthalen-1-ol, (1,3-benzoxol-5-yl)methanol, nonylphenol, dinonylphenol, nonylphenol ethoxylate, monostyrenated phenol, distyrenated phenol, tristyrenated phenol, etc. These can be used alone or in combination of two or more.

[0069] The hydroxyl group-containing monomer preferably contains a hydroxyl group-containing monomer having an alicyclic skeleton from the viewpoint of stain resistance of the coating film to be formed, etc. Examples of the hydroxyl group-containing monomer having an alicyclic skeleton include 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol F.

[0070] Furthermore, from the viewpoint of the scratch recovery properties of the coating film to be formed, etc., the hydroxyl group-containing monomer preferably contains a hydroxyl group-containing monomer having two isocyanate-reactive groups. When a hydroxyl group-containing monomer is contained as the hydroxyl group-containing compound (A1), from the viewpoint of the stain resistance, scratch recovery properties, smoothness, etc. of the coating film to be formed, the content of the hydroxyl group-containing monomer is preferably within the range of 5 to 100 mass%, more preferably within the range of 5 to 70 mass%, and even more preferably within the range of 5 to 60 mass%, based on the total solid content of the hydroxyl group-containing compound (A1). When the hydroxyl group-containing compound (A1) is contained as the isocyanate-reactive group-containing compound (A), the content of the hydroxyl group-containing compound (A1) is preferably in the range of 50 to 100 mass %, more preferably in the range of 60 to 100 mass %, and even more preferably in the range of 70 to 100 mass %, based on the total solids content of the isocyanate-reactive group-containing compound (A), from the viewpoints of the contamination resistance, scratch recovery, smoothness, and the like of the coating film to be formed.

[0071] [Amino Group-Containing Compound (A2)] The amino group-containing compound (A2) is a compound having at least one primary amino group and / or one secondary amino group in the molecule. Examples of the amino group-containing compound (A2) include aliphatic polyamines such as ethylenediamine, pentamethylenediamine, hexamethylenediamine, trimethylhexamethylenediamine, diethylenetriamine, dipropylenetriamine, triethylenetetramine, N,N'-bis-(3-aminopropyl)ethylenediamine, and tetraethylenepentamine; 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, and 1,4-cyclohexanediamine; 4-methyl-1,3-cyclohexanediamine, 2-methyl-1,3-cyclohexanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 3,3'-dimethyl-4,4'-methylenebis(cyclohexylamine), N,N'-(isophoronediamino)bispropionitrile, N,N'-di-sec-butyl-4,4'-methylenebis(cyclohexylamine), 1,2-bis(aminomethyl)cyclohexane, 1,3-bis alicyclic polyamines such as bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, and norbornanediamine; heterocyclic polyamines such as piperazine and N-(2-aminoethyl)piperazine; 2,4-toluenediamine, 2,6-toluenediamine, 4,4'-diaminodiphenylmethane, diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-methylenebis[N-(1-methylpropyl)aniline], 4,4'-diamino aromatic polyamines such as diphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, aminobenzylamine, m-xylylenediamine, p-xylylenediamine, and N,N'-di-sec-butyl-p-phenylenediamine;Polyether polyamine compounds such as polyoxypropylene diamine, polyoxyethylene diamine, poly(oxyethylene / oxypropylene) diamine, trimethylolpropane poly(oxypropylene) triamine, and glyceryl poly(oxypropylene) triamine; N,N'-(2-methylpentane-1,5-diyl)bisaspartic acid tetraethyl ester, N,N'-[methylenebis(cyclohexane-4,1-diyl)]bisaspartic acid tetraethyl ester, N,N'-[methylenebis(2-methylcyclohexane-4,1-diyl)]bisaspartic acid tetraethyl ester, and N,N'-[methylenebis(2-methylcyclohexane-4,1-diyl)]bisaspartic acid tetraethyl ester. ]bisaspartic acid ester compounds such as tetraethyl aspartate and α-{2-[(1,4-diethoxy-1,4-dioxobutan-2-yl)amino]propyl}-ω-{2-[(1,4-diethoxy-1,4-dioxobutan-2-yl)amino]propoxy}poly[oxy(methylethylene)]; and aminosilane compounds such as N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and γ-anilinopropyltrimethoxysilane. These can be used alone or in combination of two or more.

[0072] From the viewpoint of the contamination resistance of the coating film to be formed, the amino group-containing compound (A2) preferably contains at least one compound selected from aliphatic polyamines, alicyclic polyamines, polyether polyamine compounds, and polyaspartic acid ester compounds, and more preferably contains at least one compound selected from alicyclic polyamines and polyaspartic acid esters.

[0073] From the viewpoint of the scratch recovery properties of the coating film to be formed, etc., the amino group-containing compound (A2) preferably comprises an amino group-containing compound having two isocyanate-reactive groups. Furthermore, from the viewpoints of reducing the VOC content in the resulting coating composition and of the contamination resistance, scratch recovery properties, and smoothness of the coating film to be formed, the amino group-containing compound (A2) preferably comprises an amino group-containing compound having a number average molecular weight in the range of 300 to 1,000, more preferably an amino group-containing compound having a number average molecular weight in the range of 400 to 850, and even more preferably an amino group-containing compound having a number average molecular weight in the range of 450 to 600.

[0074] As the amino group-containing compound (A2), commercially available products can be used. Examples of commercially available product names include "Baxodur EC110", "DETA", "N4 Amine", "Baxodur EC210", "Baxodur EC201", "Baxodur EC330", "Baxodur EC331", "Baxodur PC136", "Baxodur EC130", "Baxodur EC280", "Baxodur EC301", "Baxxodur EC302", "Baxxodur EC303", "Baxxodur EC310", and "Baxxodur EC311" (all of which are product names manufactured by BASF), "Clearlink 1000", "Unilink 4200", and "Unilink 4100'' (all product names, manufactured by DORF KETAL), ``JEFFAMINE M-600'', ``JEFFAMINE M-1000'', ``JEFFAMINE M-2005'', ``JEFFAMINE M-2070'', ``JEFFAMINE M-3085'', ``JEFFAMINE D-230'', ``JEFFAMINE D-400'', ``JEFFAMINE D-2000'', ``JEFFAMINE D-4000'', ``JEFFAMINE ED-600'', ``JEFFAMINE ED-900", "JEFFAMINE ED-2003", "JEFFAMINE EDR-148", "JEFFAMINE RT-1000," "JEFFAMINE T-403," "JEFFAMINE T-3000," "JEFFAMINE T-5000" (all trade names, manufactured by HUNTSMAN), "MXDA," "1,3-BAC" (all trade names, manufactured by Mitsubishi Gas Chemical Company, Inc.), "WANAMINE MDA-100H", "Ethacure 100 Plus", "Ethacure 300", "Ethacure 420", "Bisaniline-M", "Bisaniline-P" (all trade names, manufactured by Mitsui Fine Chemicals, Inc.), "VESTAMIN IPD", "VESTAMIN TMD", "VESTAMIN PACM", "ANCAMINE 2049" (all trade names, manufactured by EVONIK Industries), “D.E.H.20”, “D.E.H.24”, “D.E.H.26”, “D.E.H.29”, “D.E.H.39”, “D.E.H.444”, “D.E.H. 445", "D.E.H.4042", "D.E.H.4044", "D.E.H.487", "D.E.H.488", "D.E.H.530", "D.E.H." Dow Chemical Co., Ltd.), "Desmophen NH1220", "Desmophen NH1420", "Desmophen NH1422", "Desmophen NH1423", "Desmophen NH1520", "Desmophen NH1521", "Desmophen NH1523" (all trade names, manufactured by Covestro), "FEISPARTIC F220", "FEISPARTIC F420", "FEISPARTIC F520", "FEISPARTIC F2850" (all trade names, manufactured by Feiyang Protech), "TSE-EZASP 9033" (trade name, manufactured by TSE Industries).

[0075] Commercially available products can be used as the alicyclic polyamine. Examples of commercially available products under trade names include "Baxodur EC210," "Baxodur EC201," "Baxodur EC330," "Baxodur EC331," and "Baxodur PC136" (all trade names, manufactured by BASF), "Clearlink 1000" (all trade names, manufactured by DORF KETAL), "1,3-BAC" (all trade names, manufactured by Mitsubishi Gas Chemical Company, Inc.), "WANAMINE MDA-100H" (all trade names, manufactured by Mitsui Fine Chemicals, Inc.), "VESTAMIN IPD," "VESTAMIN PACM," and "ANCAMINE 2049" (all trade names, EVONIK (all trade names, manufactured by The Dow Chemical Company), "Desmophen NH1420", "Desmophen NH1422", "Desmophen NH1423", "Desmophen NH1520", "Desmophen NH1521", "Desmophen NH1523" (all trade names, manufactured by Covestro), "FEISPARTIC F420", "FEISPARTIC F520" (all trade names, manufactured by Feiyang and "TSE-EZASP 9033" (all trade names, manufactured by TSE Industries).

[0076] When the amino group-containing compound (A2) is contained as the isocyanate-reactive group-containing compound (A), the content of the amino group-containing compound (A2) is preferably in the range of 10 to 100 mass%, more preferably in the range of 25 to 100 mass%, and even more preferably in the range of 40 to 100 mass%, based on the total solid content of the isocyanate-reactive group-containing compound (A), from the viewpoints of the contamination resistance and scratch recovery properties of the coating film to be formed.

[0077] [Thiol Group-Containing Compound (A3)] The thiol group-containing compound (A3) is a compound having at least one thiol group in one molecule. Examples of the thiol group-containing compound (A3) include pentaerythritol tetrakis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, tetraethylene glycol bis(3-mercaptopropionate), tetramethylene glycol bis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), trimethylolpropane dipropanethiol, pentaerythritol tetrakis(3-mercaptopropionate), trimethylolpropane dipropanethiol, and pentaerythritol tetrakis(3-mercaptopropionate). Examples include thritol tripropanethiol, pentaerythritol tetrapropanethiol, 1,4-bis(mercaptomethyl)benzene, pentaerythritol tetrakis(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptobutyrate), tetramethylene glycol bis(3-mercaptobutyrate), tris-[(3-mercaptobutyroyloxy)-ethyl]-isocyanurate, trimethylolpropane tris(thioglycolate), pentaerythritol tetrakis(thioglycolate), etc. These can be used alone or in combination of two or more.

[0078] As the thiol group-containing compound (A3), commercially available products can be used. Examples of commercially available trade names include "TMMP-LV", "TEMPIC", "PEMP-LV", "DPMP", "EGMP-4", "BDMP", "Multiol Y-3", "Multiol Y-4", "PXDT" (all trade names, manufactured by SC Organic Chemical Co., Ltd.), "BDTG", "HDTG", "TMTG", "PETG", "EGTP", "BDTP", "TMTP", "PETP" (all trade names, manufactured by Yodo Chemical Co., Ltd.), "ADEKA Hardener EH-317" (all trade names, manufactured by ADEKA Corporation), "Karenz MT PEI", "Karenz MT BDI", "Karenz MT BD1", "Karenz MT TPMB", "Karenz MT NRI" (all trade names, manufactured by Showa Denko KK), "jER Cure QX11", "jER Cure QX40" (all trade names, manufactured by Mitsubishi Chemical Corporation), and the like. From the viewpoints of reducing the VOC content in the resulting coating composition and improving the contamination resistance, scratch recovery, smoothness, etc. of the coating film formed, the thiol group-containing compound (A3) preferably contains a thiol group-containing compound having a number average molecular weight in the range of 400 to 1,000, more preferably contains a thiol group-containing compound having a number average molecular weight in the range of 400 to 850, and even more preferably contains a thiol group-containing compound having a number average molecular weight in the range of 450 to 600.

[0079] When the isocyanate-reactive group-containing compound (A) contains the thiol group-containing compound (A3), the content of the thiol group-containing compound (A3) is preferably in the range of 5 to 100 mass%, more preferably in the range of 7 to 100 mass%, and even more preferably in the range of 10 to 100 mass%, based on the total solids content of the isocyanate-reactive group-containing compound (A), from the viewpoints of the contamination resistance and scratch recovery properties of the coating film to be formed.

[0080] In the coating composition of this embodiment, the content of the isocyanate-reactive group-containing compound (A) is preferably in the range of 15 to 80 mass %, more preferably in the range of 20 to 70 mass %, and even more preferably in the range of 25 to 50 mass %, based on the total amount of the coating composition, from the viewpoints of reducing the VOC content in the resulting coating composition and improving the contamination resistance, scratch recovery, smoothness, etc. of the coating film to be formed.

[0081] [Polyisocyanate Composition (B)] The polyisocyanate composition (B) contains a polyisocyanate compound having at least two isocyanate groups per molecule, such as an aliphatic polyisocyanate, an alicyclic polyisocyanate, an araliphatic polyisocyanate, an aromatic polyisocyanate, and derivatives of these polyisocyanates (e.g., modified compounds containing uretdione groups, allophanate groups, urethane groups, carbodiimide groups, urea groups, biuret groups, uretonimine groups, isocyanurate groups, oxazolidone groups, and iminooxadiazinedione groups), which can be used alone or in combination of two or more. However, in the present invention, compounds having a carbodiimide group and two or more isocyanate groups are not included in the polyisocyanate compound, but are included in the carbodiimide group-containing compound (C).

[0082] In the coating composition of the present invention, the polyisocyanate composition (B) has uretdione groups and allophanate groups. In the coating composition of the present invention, the molar ratio of the uretdione groups to the total of the uretdione groups and allophanate groups in the polyisocyanate composition (B) and the isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups present in the polyisocyanate composition (B) is within the range of 5 to 25%. By having the molar ratio of uretdione groups within the range of 5 to 25%, a coating film with excellent stain resistance and smoothness can be formed.

[0083] From the viewpoint of the contamination resistance and smoothness of the coating film to be formed, the molar ratio of uretdione groups to the sum of uretdione groups and allophanate groups in the polyisocyanate composition (B) and isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups present in the polyisocyanate composition (B) is preferably within the range of 6 to 22%, more preferably within the range of 7 to 20%, and even more preferably within the range of 9 to 18%. In the coating composition of the present invention, the molar ratio of allophanate groups to the sum of uretdione groups and allophanate groups in the polyisocyanate composition (B) and isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups present in the polyisocyanate composition (B) is within the range of 5 to 55%. By having the molar ratio of allophanate groups within the range of 5 to 55%, a coating film with excellent scratch recovery and smoothness can be formed.

[0084] The molar ratio of the allophanate groups to the sum of the uretdione groups and allophanate groups in the polyisocyanate composition (B) and the isocyanurate groups, urethane groups, biuret groups and iminooxadiazinedione groups present in the polyisocyanate composition (B) is preferably within the range of 10 to 50%, more preferably within the range of 15 to 47%, and even more preferably within the range of 25 to 45%, from the viewpoints of the scratch recovery and smoothness of the coating film to be formed.

[0085] Furthermore, the molar ratio of uretdione groups to allophanate groups contained in the polyisocyanate composition (B) (uretdione groups / allophanate groups) is preferably within a range of 10 / 90 to 80 / 20, more preferably within a range of 15 / 85 to 65 / 35, and even more preferably within a range of 20 / 80 to 55 / 45, from the viewpoints of the stain resistance, scratch recovery, and smoothness of the coating film to be formed. The molar ratios of uretdione groups, allophanate groups, isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups in the polyisocyanate composition (B) are as follows: １３It can be measured by C-NMR measurement.

[0086] The specific method for measuring the molar ratios of the uretdione group, allophanate group, isocyanurate group, urethane group, biuret group, and iminooxadiazinedione group in the polyisocyanate composition (B) will be described in the Examples. Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene 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, methyl 2,6-diisocyanatohexanoate (trivial name: lysine diisocyanate), and the like. aliphatic diisocyanates 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.

[0087] Examples of the alicyclic polyisocyanate include alicyclic diisocyanates such as 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: isophorone diisocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (common name: hydrogenated xylylene diisocyanate) or a mixture thereof, and norbornane diisocyanate; 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2-(3-isocyanatopropyl)-2,5-di(isocyanatomethyl)-bicyclo(2.2.1)hepta 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 alicyclic triisocyanates such as 2-isocyanatoethyl-3-(3-isocyanatopropyl)-bicyclo(2.2.1)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. Examples of the araliphatic polyisocyanate include araliphatic diisocyanates such as 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; and araliphatic triisocyanates such as 1,3,5-triisocyanatomethylbenzene.

[0088] Examples of the aromatic polyisocyanate include aromatic diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4'- or 4,4'-diphenylmethane diisocyanate or mixtures thereof, 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, 4,4'-toluidine diisocyanate, and 4,4'-diphenyl ether diisocyanate; aromatic triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatobenzene, and 2,4,6-triisocyanatotoluene; and aromatic tetraisocyanates such as 4,4'-diphenylmethane-2,2',5,5'-tetraisocyanate.

[0089] The polyisocyanates and their derivatives may be used alone or in combination of two or more. Among these polyisocyanates, aliphatic diisocyanates, aliphatic triisocyanates, alicyclic diisocyanates, araliphatic diisocyanates, and their derivatives are preferably used alone or in combination of two or more. Furthermore, the polyisocyanate compound may be a prepolymer obtained by reacting the polyisocyanate or its derivative with a compound reactive with the polyisocyanate under conditions of excess isocyanate groups. Examples of compounds reactive with the polyisocyanate include compounds having active hydrogen groups such as hydroxyl groups and amino groups. Specific examples of compounds that can be used include polyhydric alcohols, low-molecular-weight polyester resins, amines, and water.

[0090] The polyhydric alcohol can be the same as that used in the description of the hydroxyl group-containing polyester resin. From the viewpoint of the contamination resistance and scratch recovery of the coating film to be formed, the polyisocyanate composition (B) is preferably used in a proportion such that the ratio of isocyanate groups in the polyisocyanate composition (B) to the isocyanate reactive groups in the isocyanate-reactive group-containing compound (A) is within the range of 0.7 to 2.0, more preferably 0.9 to 1.5. Furthermore, from the viewpoint of the contamination resistance, scratch recovery, and smoothness of the coating film to be formed, the content of the polyisocyanate composition (B) in the coating composition of this embodiment is preferably within the range of 10 to 80 mass%, more preferably within the range of 20 to 75 mass%, and even more preferably within the range of 30 to 70 mass%, based on the total amount of the coating composition.

[0091] [Carbodiimide Group-Containing Compound (C)] The coating composition of this embodiment preferably contains a carbodiimide group-containing compound from the viewpoint of the contamination resistance of the coating film formed. The carbodiimide group-containing compound (C) is a compound having at least one carbodiimide group per molecule, and can be, for example, a compound obtained by subjecting the isocyanate groups of an isocyanate group-containing compound to a carbon dioxide removal reaction. Commercially available products can be used as the carbodiimide group-containing compound (C). Examples of commercially available products under the trade names include "Carbodilite V-02B", "Carbodilite V-05", "Elastostab H01", "Carbodilite V-03", "Carbodilite V-07", "Carbodilite V-09", "Carbodilite V-09GB", "Carbodilite V-09M", and "Carbodilite V-04PF" (all trade names, manufactured by Nisshinbo Chemical Co., Ltd.), "Stabaxol I", "Stabaxol I LF", "Stabaxol P", "Stabaxol P100", and "Stabaxol P200" (all trade names, manufactured by LANXESS). From the viewpoint of reducing the VOC content in the resulting coating composition and improving the contamination resistance of the coating film formed, it is preferable that the carbodiimide group-containing compound (C) contains a solventless carbodiimide group-containing compound.

[0092] Commercially available products can be used as the solventless carbodiimide group-containing compound. Examples of commercially available products include "Carbodilite V-02B," "Carbodilite V-05," "Elastostab H01," and "Carbodilite V-04PF" (all manufactured by Nisshinbo Chemical Inc.). The number-average molecular weight of the carbodiimide group-containing compound (C) is preferably within the range of 500 to 5,000, more preferably within the range of 600 to 3,000, and even more preferably within the range of 700 to 1,500, from the viewpoints of reducing the VOC content in the resulting coating composition and improving the contamination resistance of the coating film formed.

[0093] When the coating composition of the present embodiment contains the carbodiimide group-containing compound (C), the content of the carbodiimide group-containing compound (C) is preferably in the range of 0.1 to 5 mass %, more preferably in the range of 0.2 to 4 mass %, and even more preferably in the range of 0.3 to 3 mass %, based on the total amount of the coating composition, from the viewpoint of the contamination resistance of the coating film to be formed, etc.

[0094] [Other Components] In addition to the above, the coating composition of this embodiment may further contain an ultraviolet absorber and / or a light stabilizer. Furthermore, if necessary, other additive components commonly used in the field of coating, such as an internal mold release agent, a crosslinking agent, a solvent (organic solvent, water), a pigment, a catalyst, a dehydrating agent, an antioxidant, a surface conditioner, an antifoaming agent, an emulsifier, a surfactant, an antifouling agent, a wetting agent, a thickener, a dye, an abrasion resistance improver, and a gloss adjuster, may be appropriately contained.

[0095] [Ultraviolet Absorber] As the ultraviolet absorber, conventionally known ones can be used, for example, benzotriazole-based absorbers, triazine-based absorbers, salicylic acid derivative-based absorbers, benzophenone-based absorbers, etc. Furthermore, the ultraviolet absorber may have a polymerizable unsaturated group.

[0096] Specific examples of the benzotriazole-based absorbents include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, 2-{2'-hydroxy-3'-(3'',4'',5'',6''-tetrahydrophthalimidomethyl)-5'-methylphenyl}benzotriazole, 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole, and the like. Specific examples of the triazine-based absorbent include 2,4-bis(2,4-dimethylphenyl)-6-(2-hydroxy-4-isooctyloxyphenyl)-1,3,5-triazine, 2-[4((2-hydroxy-3-dodecyloxypropyl)-oxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-((2-hydroxy-3-tridecyloxypropyl)-oxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, and 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine.

[0097] Specific examples of the salicylic acid derivative-based absorbents include phenyl salicylate, p-octylphenyl salicylate, and 4-tert-butylphenyl salicylate.

[0098] Specific examples of the benzophenone-based absorbents include 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, and naphthalene. Examples include thorium 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, resorcinol monobenzoate, 2,4-dibenzoylresorcinol, 4,6-dibenzoylresorcinol, hydroxydodecylbenzophenone, and 2,2'-dihydroxy-4(3-methacryloxy-2-hydroxypropoxy)benzophenone.

[0099] Commercially available examples of the ultraviolet absorber include "TINUVIN 1130," "TINUVIN 900," "TINUVIN 928," "TINUVIN 384-2," "TINUVIN 479," "TINUVIN 477," "TINUVIN 405," "TINUVIN 400" (trade names manufactured by BASF, TINUVIN is a registered trademark), and "RUVA 93" (trade name manufactured by Otsuka Chemical Co., Ltd.).

[0100] When the coating composition of the present embodiment contains the above-mentioned ultraviolet absorber, the content of the ultraviolet absorber is preferably in the range of 0.1 to 10 mass %, more preferably in the range of 0.2 to 5.0 mass %, and even more preferably in the range of 0.3 to 3.0 mass %, based on the total amount of the coating composition, from the viewpoint of the contamination resistance of the coating film to be formed, etc.

[0101] [Light Stabilizer] The light stabilizer is used as a radical chain inhibitor that captures active radical species generated during the deterioration process of the coating film, and examples thereof include light stabilizers of hindered amine compounds.

[0102] Examples of the hindered amine compound include bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, bis(N-methyl-2,2,6,6-tetramethyl-4-piperidinyl)sebacate, 4-benzoyloxy-2,2',6,6'-tetramethylpiperidine, bis(1,2,2,6,6-pentamethyl-4-piperidyl){[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl}butylmalonate, Examples of the light stabilizer include, but are not limited to, monomeric types such as methyl acrylate, methyl meth ...

[0103] Examples of commercially available light stabilizers include "TINUVIN 123", "TINUVIN 152", "TINUVIN 249", and "TINUVIN 292" (manufactured by BASF, trade names, TINUVIN is a registered trademark), "HOSTAVIN 3058" (manufactured by Clariant, trade name, Hostavin is a registered trademark), and "ADK STAB LA-82" (manufactured by ADEKA Corporation, trade name, ADK STAB is a registered trademark). When the coating composition of this embodiment contains the above-mentioned light stabilizer, the content of the light stabilizer is preferably in the range of 0.1 to 10 mass%, more preferably in the range of 0.2 to 7.5 mass%, and even more preferably in the range of 0.3 to 5.0 mass%, based on the total amount of the coating composition, from the viewpoint of the contamination resistance of the coating film to be formed.

[0104] [Internal mold release agent] When the coating composition of the present embodiment is used as an in-mold coating coating composition, it is preferable that the coating composition of the present embodiment contains an internal mold release agent from the viewpoint of the releasability between the formed coating film and the mold.

[0105] Examples of the internal mold release agent include saturated fatty acids such as stearic acid and palmitic acid; saturated fatty acid salts such as zinc stearate, aluminum stearate, magnesium stearate, calcium stearate, sodium stearate, potassium stearate, barium stearate, zinc palmitate, aluminum palmitate, magnesium palmitate, calcium palmitate, and sodium palmitate; saturated fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, N,N-dimethyllauric acid amide, N,N-dimethylmyristic acid amide, N,N-dimethylpalmitic acid amide, N,N-dimethylstearic acid amide, N,N-diethyllauric acid amide, N,N-diethylmyristic acid amide, N,N-diethylpalmitic acid amide, and N,N-diethylstearic acid amide; unsaturated fatty acids such as palmitoleic acid and oleic acid; zinc palmitoleate, aluminum palmitoleate, palmitic acid amide, and the like. unsaturated fatty acid salts such as magnesium oleate, calcium palmitoleate, sodium palmitoleate, potassium palmitoleate, barium palmitoleate, zinc oleate, aluminum oleate, magnesium oleate, calcium oleate, sodium oleate, potassium oleate, and barium oleate; unsaturated fatty acid amides such as palmitoleic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, N-oleyl palmitic acid amide, N-stearyl erucic acid amide, N,N-dimethyl oleic acid amide, and N,N-diethyl oleic acid amide; nonionic surfactants such as polyoxyethylene alkyl ethers and sorbitan alkyl esters; fluorine-based compounds such as polytetrafluoroethylene, fluoropolyethers, perfluoroalkyl esters, and perfluoroalkyl ester salts; phosphate ester compounds such as phosphate monoesters and / or phosphate diesters having alkyl chains or oxyethylene chains, etc.;Stearic acid monoglyceride, stearic acid diglyceride, stearic acid triglyceride, stearate monosorbitate, stearate stearyl, palmitic acid monoglyceride, palmitic acid diglyceride, palmitic acid triglyceride, behenic acid monoglyceride, behenic acid diglyceride, behenic acid triglyceride, behenyl behenate, pentaerythritol monostearate, pentaerythritol tetrastearate, pentaerythritol tetrapelargonate, propyl Examples of fatty acid esters include ethylene glycol monostearate, stearyl stearate, palmityl palmitate, methyl stearate, butyl stearate, methyl laurate, methyl palmitate, isopropyl palmitate, biphenyl biphenate, sorbitan monostearate, and 2-ethylhexyl stearate; soybean oil lecithin, silicone oil, and fatty acid alcohol dibasic acid esters, which can be used alone or in combination of two or more types;

[0106] When the coating composition of the present embodiment contains the internal release agent, the content of the internal release agent is preferably in the range of 0.1 to 5.0 mass %, more preferably in the range of 0.2 to 4.0 mass %, and even more preferably in the range of 0.2 to 3.0 mass %, based on the total amount of the coating composition, from the viewpoint of the releasability between the formed coating film and the mold.

[0107] [Solvent] Examples of the solvent that can be used include organic solvents, water, etc. Examples of the organic solvent include ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester-based solvents such as ethyl acetate, butyl acetate, methyl benzoate, ethyl ethoxypropionate, ethyl propionate, and methyl propionate; ether-based solvents such as tetrahydrofuran, dioxane, and dimethoxyethane; glycol ether-based solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; aromatic solvents such as toluene, xylene, and "Swasol 1000" (trade name, high-boiling point petroleum solvent, manufactured by Cosmo Oil Co., Ltd.); and aliphatic hydrocarbon-based solvents such as hexane and heptane.

[0108] The content of the solvent in the coating composition of this embodiment is within the range of 0 to 10 mass % based on the total amount of the coating composition. From the viewpoint of reducing the VOC content in the resulting coating composition, the content of the solvent in the coating composition of this embodiment is preferably within the range of 0 to 5 mass %, and more preferably within the range of 0 to 3 mass %.

[0109] [Pigments] Examples of the pigments include luster pigments, color pigments, and extender pigments. These pigments can be used alone or in combination of two or more. Examples of the luster pigments include aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, glass flakes, aluminum oxide, mica, aluminum oxide coated with titanium oxide and / or iron oxide, and mica coated with titanium oxide and / or iron oxide. Examples of the color pigments include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, threne pigments, perylene pigments, dioxazine pigments, diketopyrrolopyrrole pigments, and heat-shielding pigments.

[0110] Examples of the extender pigment include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, alumina white, etc. When the coating composition of this embodiment contains the above-mentioned pigment, the content of the pigment is preferably in the range of 0.1 to 40 mass %, more preferably in the range of 0.2 to 30 mass %, and even more preferably in the range of 0.3 to 20 mass %, based on the total amount in the coating composition, from the viewpoints of reducing the VOC content in the resulting coating composition and improving scratch recovery and smoothness.

[0111] [Catalyst] A conventionally known catalyst can be used. Examples of the catalyst include tin octoate, dibutyltin diacetate, dibutyltin di(2-ethylhexanoate), dibutyltin dilaurate, dioctyltin diacetate, dioctyltin di(2-ethylhexanoate), dioctyltin dineodecanoate, dioctyltin diversatate, dibutyltin oxide, dibutyltin sulfide, dioctyltin oxide, dibutyltin fatty acid salts, lead 2-ethylhexanoate, zinc octoate, zinc naphthenate, zinc fatty acids, bismuth octanoate, bismuth 2-ethylhexanoate, bismuth oleate, bismuth neodecanoate, and versatane. organometallic compounds such as bismuth titanate, bismuth naphthenate, cobalt naphthenate, calcium octylate, copper naphthenate, tetra(2-ethylhexyl)titanate, tetra(n-butyl)titanate, titanium diisopropoxybis(acetylacetonate), titanium tetraacetylacetonate, titanium diisopropoxybis(ethylacetoacetate), titanium butoxide dimer, zirconium tetra-n-propoxide, zirconium tetra-n-butoxide, zirconium tetraacetylacetonate, and zirconium tributoxymonoacetylacetonate;Triethylamine, N,N'-dimethylcyclohexylamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N',N'',N''-pentamethyldiethylenetriamine, N,N,N',N'',N''-pentamethyldipropylenetriamine, 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), 1,5-diazabicyclo[4.3.0]-pentane (PBB ... tertiary amine compounds such as 1-(2-dimethylaminoethyl)-5-nonene (DBN), N-methyl-N'-(2-dimethylaminoethyl)piperazine, N-ethylmorpholine, 1,2-dimethylimidazole, dimethylethanolamine, dimethylaminoethoxyethanol, N-methyl-N'-(2-hydroxyethyl)piperazine, 2-hydroxyethyl-1,4-diazabicyclo[2.2.2]octane, 1,1'-{[3-(dimethylamino)propyl]imino}bis(2-propanol), bis(2-dimethylaminoethyl)ether, and bis(2-morpholinoethyl)ether, as well as neutralized salts of the tertiary amine compounds; and quaternary ammonium salts such as carboxylates of tetraalkylammonium, tetraarylammonium, and alkylarylammonium, and halides of tetraalkylammonium, tetraarylammonium, and alkylarylammonium, which can be used alone or in combination of two or more kinds.

[0112] When the coating composition of the present embodiment contains the above catalyst, from the viewpoint of the contamination resistance and scratch recovery properties of the coating film to be formed, the amount of catalyst blended is preferably in the range of 0.005 to 2 mass %, and more preferably in the range of 0.01 to 1 mass %, based on the total amount of the coating composition.

[0113] Furthermore, when the coating composition of the present embodiment contains the above-mentioned catalyst, it may also contain organic acids such as acetic acid, propionic acid, butyric acid, isopentanoic acid, hexanoic acid, 2-ethylbutyric acid, naphthenic acid, octylic acid, nonanoic acid, decanoic 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; and metal coordination compounds such as acetylacetone and imidazole-based compounds.

[0114] [Dehydrating Agent] Conventionally known inorganic and organic dehydrating agents can be used as the dehydrating agent. Examples of the inorganic dehydrating agent include calcium compounds such as calcium hydride, calcium oxide (quicklime), calcium chloride, and calcium sulfate (gypsum); barium compounds such as barium oxide; magnesium compounds such as magnesium sulfate; sodium compounds such as sodium sulfate and sodium carbonate; copper compounds such as copper sulfate; inorganic silicon compounds such as silica gel; and aluminum compounds such as aluminum oxide (hydraulic alumina, lithium aluminum hydride, amorphous silica alumina, and crystalline aluminosilicates (molecular sieves). These can be used alone or in combination of two or more.

[0115] Examples of the organic dehydrating agent include alkyl orthoformate, alkyl orthoacetate, alkyl orthoborate, vinylsilane, alkoxysilane compounds, monoisocyanate compounds, aliphatic acid anhydrides such as acetic anhydride, and aromatic acid anhydrides such as benzoic anhydride, and these can be used alone or in combination of two or more. When the coating composition of this embodiment contains the dehydrating agent, from the viewpoint of the contamination resistance and scratch recovery properties of the coating film formed, the amount of the dehydrating agent is preferably in the range of 0.1 to 2 mass%, and more preferably in the range of 0.3 to 1 mass%, based on the total amount of the coating composition.

[0116] [Method for forming a coating film using a coating composition] The coating composition of the present embodiment is applied to a substrate to form a wet coating film (uncured coating film), and then the wet coating film is cured to form the desired coating film.

[0117] The substrate is preferably a resin material from the viewpoint of adhesion of the coating film to be formed and releasability of the coating film to be formed from the mold, etc. Examples of the resin material include acrylic resins such as polymethyl methacrylate, polyester resins such as polyethylene terephthalate, polyethylene naphthalate, poly-1,4-cyclohexanedimethylene terephthalate, polyethylene-1,2-diphenoxyethane-4,4'-dicarboxylate, and polybutylene terephthalate, epoxy resins represented by commercially available products such as Epicoat (trade name: manufactured by Yuka Shell Epoxy Co., Ltd.), polycarbonate resins, polyimide resins, novolac resins, phenolic resins, acrylonitrile-butadiene-styrene (ABS) resins, acrylonitrile-ethylene-styrene (AES) resins, and acrylic resins. Examples of the resin include lylonitrile-styrene-acrylate (ASA) resin, vinyl chloride resin, vinylidene chloride resin, polyurethane resin, cellulose ester resin (e.g., triacetyl cellulose, diacetyl cellulose, propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose, nitrocellulose), polyamide resin, polystyrene resin (e.g., syndiotactic polystyrene), polyolefin resin (e.g., polypropylene, polyethylene, polymethylpentene), polysulfone resin, polyethersulfone resin, polyarylate resin, polyetherimide resin, polyetherketone resin, various fiber reinforced plastic materials (Fiber Reinforced Plastics: hereinafter sometimes abbreviated as FRP material or simply FRP), as well as polymer alloys thereof, recycled materials thereof, etc. Furthermore, the resin material may be mixed with a compound containing a reactive functional group such as a hydroxyl group, amino group, mercapto group, silanol group, vinyl group, or epoxy group, or wood fiber, cellulose nanofiber, kenaf, etc., to form the substrate.

[0118] The substrate may be, for example, one obtained by coating the resin material with a primer coating, an intermediate coating, a top coating, etc., to form a primer layer, an intermediate coating layer, a top coating layer, etc. The substrate may also be one that has been subjected to treatment (physical treatment) by at least one physical method selected from plasma treatment, corona discharge treatment, active energy ray treatment, flame treatment, blast treatment, polishing treatment, etc.

[0119] The coating composition of this embodiment is preferably applied directly to a substrate. The application of the coating composition of this embodiment to the substrate is not particularly limited, and examples thereof include outer panels of automobile bodies such as passenger cars, trucks, motorcycles, and buses; interior and exterior automotive parts such as bumpers, center pillars, mirrors, door handles, instrument panels, door trims, and center consoles; furniture and building materials such as chairs, vanity mirrors, window frames, and gates; and outer panels of household electrical appliances such as mobile phones and audio equipment. The method for applying the coating composition of this embodiment to a substrate is not particularly limited. For example, the coating can be applied by air spray, airless spray, rotary atomizer, dip coating, applicator, brush, roller, in-mold coating, or the like. Electrostatic application may be performed during application.

[0120] From the viewpoint of scratch recovery of the formed coating film, the coating film thickness is preferably in the range of 70 to 1000 μm, more preferably in the range of 100 to 900 μm, and even more preferably in the range of 200 to 800 μm, in terms of the cured film thickness. The coating composition of this embodiment can be cured on the substrate by heating the coating composition.

[0121] [Heating] Heating can be performed using any method known in this field. Specifically, for example, hot air, hot gas, infrared heater, IR radiator, oven, heated roller, hot press, microwave, etc. In this embodiment, from the viewpoint of ease of work, etc., heating is preferably performed using hot air, infrared heater, hot press, etc. The heating temperature is preferably in the range of 30 to 200°C, more preferably in the range of 50 to 180°C, and even more preferably in the range of 70 to 160°C, from the viewpoints of productivity, workability, and thermal stability of the substrate, etc.

[0122] The heating time is preferably within a range of 20 seconds to 60 minutes, and more preferably within a range of 40 seconds to 10 minutes. The coating composition of this embodiment can also be suitably used in coating by an in-mold coating method. This in-mold coating method typically allows the use of a coating composition with a low VOC content, and further reduces the air conditioning energy required during coating, thereby offering the advantage of reducing the environmental impact.

[0123] [In-mold coating method] The in-mold coating method according to this embodiment comprises the steps of injecting the coating composition according to this embodiment (hereinafter, when the coating composition according to this embodiment is used in the in-mold coating method, it will be referred to as the in-mold coating coating composition) between the molded substrate and the inner wall of the mold, curing the in-mold coating coating composition, and then removing the coated molded article from the mold.

[0124] As the in-mold coating method, any conventional method of molding and coating in a mold can be used without any particular limitation. Specifically, for example, the methods described in JP-A 2000-141407 and JP-A 2008-525212 can be used. Note that the resin molding mold used when molding the resin material and the in-mold coating mold used when in-mold coating with the in-mold coating paint composition may be the same or different.

[0125] When the resin molding mold and the in-mold coating mold are the same, for example, a heated and molten resin material is injected in an injection cylinder between the resin molding molds having the shape of the desired molded product, cooled and pressurized in the resin molding mold to form a molded product from the resin material, and then the resin molding mold is separated from the surface of the molded product made of the resin material. Next, a gap sufficient for injecting an in-mold coating paint composition is provided between the surface of the molded product made of the resin material and the in-mold coating mold, and the in-mold coating paint composition is injected between the surface of the molded product made of the resin material and the inner wall of the in-mold coating mold. The in-mold coating mold is then closed to form an uncured in-mold coating film on the molded product made of the resin material. Next, the uncured in-mold coating film formed on the molded product made of the resin material is heated and molded into the desired shape, resulting in an in-mold coated molded product in which a cured in-mold coating film is formed on the molded product made of the resin material.

[0126] When the resin molding mold and the first coating film coated mold are different, for example, a heated and molten resin material is injected in an injection cylinder between resin molding molds having the shape of the desired molded product, cooled and pressurized in the resin molding mold, the resin material is molded into a molded product, and the resin molding mold is then separated from the surface of the molded product made of the resin material and removed. Next, the in-mold coating mold is brought close to the surface of the resin molded product, a gap sufficient to inject an in-mold coating paint composition is provided between the surface of the molded product made of the resin material and the in-mold coating mold, and the in-mold coating paint composition is injected between the surface of the molded product made of the resin material and the inner wall of the in-mold coating mold. The in-mold coating mold is then closed, and an uncured in-mold coating film is formed on the molded product made of the resin material. Next, the uncured in-mold coating film formed on the molded product made of the resin material is heated and molded into the desired shape, resulting in an in-mold coated molded product having a cured in-mold coating film formed on the molded product made of the resin material.

[0127] Furthermore, from the viewpoint of the releasability between the in-mold coated molded article and the in-mold coated mold, an external mold release agent may be applied to the mold. Examples of such external mold release agents that can be used include fluorine-based, silicone-based, surfactant-based, and wax-based external mold release agents. The heating temperature when melting the resin in the injection cylinder is determined arbitrarily depending on the type of resin material, etc., but is preferably 80 to 300°C. The mold temperature when injecting the resin material is determined arbitrarily depending on the molding time, type of resin material, etc., but is preferably 30 to 120°C.

[0128] The molding time for the resin material may be until the resin material is completely solidified, but it is sufficient that the resin material is solidified to a strength that does not impair the molded shape when the in-mold coating paint composition is poured, and is usually preferably about 20 seconds to 60 minutes. The amount of the in-mold coating paint composition poured is an amount sufficient to obtain the desired film thickness, and from the viewpoint of the scratch recovery of the formed coating film, an amount sufficient to obtain a cured film thickness of 70 to 1000 μm is preferred, an amount sufficient to obtain a cured film thickness of 100 to 900 μm is more preferred, and an amount sufficient to obtain a cured film thickness of 200 to 800 μm is even more preferred.

[0129] The heating temperature when the uncured in-mold coating film is heated is preferably within the range of 20 to 160°C, more preferably within the range of 40 to 150°C, and even more preferably within the range of 60 to 140°C.

[0130] Furthermore, the heating time for heating the uncured in-mold coating film is preferably within a range of 20 seconds to 10 minutes, more preferably within a range of 30 seconds to 5 minutes, and even more preferably within a range of 40 seconds to 4 minutes.

[0131] When the uncured in-mold coating film is heated and cured, it is preferable to apply pressure. When applying pressure, the pressure is preferably within the range of 2 to 14 MPa from the viewpoint of the water-resistant adhesion and popping resistance of the coating film to be formed.

[0132] Hereinafter, this embodiment will be described in more detail with reference to Production Examples, Examples, and Comparative Examples. Note that these Production Examples, Examples, and Comparative Examples are merely illustrative and are not intended to limit the scope of the present invention. In the Production Examples, Examples, and Comparative Examples, "parts" and "%" are based on mass unless otherwise specified. Furthermore, the film thickness of the coating film is based on the cured coating film. The components used in the following examples are as follows.

[0133] [Preparation of Hydroxyl-Containing Acrylic Resin Composition] Preparation Example 1: 40 parts of 1,4-cyclohexanedimethanol were charged into a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube, and dropping device. The charged liquid was stirred at 150°C while nitrogen gas was blown into the reaction vessel, and a monomer mixture consisting of 25 parts of styrene, 15 parts of methyl methacrylate, 20 parts of n-butyl acrylate, 40 parts of 2-hydroxyethyl methacrylate, and 8 parts of di-tertiary amyl peroxide (polymerization initiator) was added dropwise at a uniform rate over 4 hours. The reaction system was then aged at 150°C for 1 hour and then cooled to obtain a hydroxyl-containing acrylic resin composition (A1-1) with a solids concentration of 100% by mass. The hydroxyl value of the hydroxyl-containing acrylic resin in the resulting hydroxyl-containing acrylic resin composition (A1-1) was 172 mgKOH / g, the number average molecular weight was 1,900, and the glass transition temperature was 39.0°C.

[0134] Production Example 2: 40 parts of 1,4-cyclohexanedimethanol were charged into a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube, and dropping device. The charged liquid was stirred at 150°C while nitrogen gas was blown into the reaction vessel, and a monomer mixture consisting of 23 parts of styrene, 3 parts of methyl methacrylate, 34 parts of n-butyl acrylate, 40 parts of 2-hydroxyethyl methacrylate, and 8 parts of di-tertiary amyl peroxide (polymerization initiator) was added dropwise at a uniform rate over 4 hours. The reaction system was then aged at 150°C for 1 hour and then cooled to obtain a hydroxyl-containing acrylic resin composition (A1-2) with a solids concentration of 100% by mass. The hydroxyl value of the hydroxyl-containing acrylic resin in the resulting hydroxyl-containing acrylic resin composition (A1-2) was 172 mgKOH / g, the number average molecular weight was 1,900, and the glass transition temperature was 15.3°C.

[0135] Production Example 3: 40 parts of 1,4-cyclohexanedimethanol was charged into a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube, and dropping device. The charged liquid was stirred at 150°C while nitrogen gas was blown into the reaction vessel, and a monomer mixture consisting of 20 parts of styrene, 10 parts of methyl methacrylate, 35 parts of 2-ethylhexyl acrylate, 35 parts of 2-hydroxyethyl methacrylate, and 8 parts of di-tertiaryamyl peroxide (polymerization initiator) was added dropwise at a uniform rate over 4 hours. The reaction system was then aged at 150°C for 1 hour and then cooled to obtain a hydroxyl-containing acrylic resin composition (A1-3) with a solids concentration of 100% by mass. The hydroxyl value of the hydroxyl-containing acrylic resin in the resulting hydroxyl-containing acrylic resin composition (A1-3) was 151 mgKOH / g, the number average molecular weight was 1,900, and the glass transition temperature was -8.7°C.

[0136] [Production of Pigment Dispersion (P)] Production Example 4 Into a container equipped with a stirrer, 4.7 parts of butyl acetate, 1 part of "Raven 5000 ULTRA III POWDER" (trade name, manufactured by BIRLA CARBON, carbon black pigment, solids concentration 100%), 0.1 parts of "SOLSPERSE 5000S" (trade name, manufactured by LUBRISOL, phthalocyanine pigment derivative, solids concentration 100%), and 1 part of "DISPERBYK-2013" (trade name, manufactured by BYK-Chemie, dispersant, solids concentration 100%) were placed and mixed uniformly. The resulting mixed solution was then placed in a wide-mouth glass bottle, and glass beads with a diameter of approximately 1.3 mm were added as a dispersion medium, the bottle was sealed, and the mixture was dispersed for 4 hours using a paint shaker to obtain pigment dispersion (P-1).

[0137] [Production of Coating Composition] Example 1 Into a vessel equipped with a stirrer were placed 30.0 parts of "FLEXOREZ 148" (trade name, manufactured by KING INDUSTRIES, polyester resin having two hydroxyl groups and an alicyclic skeleton, number average molecular weight 480, solids concentration 100%), 70.0 parts of "Desmophen XP2488" (trade name, manufactured by Covestro, a mixture of 26% of a monomer having two hydroxyl groups and an alicyclic skeleton with a number average molecular weight of less than 300 and 76% of a polyester resin having more than two hydroxyl groups and no alicyclic skeleton with a number average molecular weight of 960, solids concentration 100%), 60.0 parts of "Desmodur N3400" (trade name, manufactured by Sumika Covestro Urethane Co., Ltd., polyisocyanate having uretdione groups, solids concentration 100%), and 100.0 parts of "Desmodur N3500 (trade name, manufactured by Sumika Covestro Urethane Co., Ltd., polyisocyanate having an allophanate group, solid content concentration 100%) 90.0 parts, "Carbodilite V-05" (trade name, manufactured by Nisshinbo Chemical Co., Ltd., carbodiimide group-containing compound having an isocyanate group, carbodiimide equivalent per solid content 262, number average molecular weight 800, solid content concentration 100%) 1.5 parts, "Moldwiz INT-120IMC" (trade name, manufactured by AXEL PLASTICS, fatty acid tertiary dimethylamide-containing mixture, solid content concentration 100%) 0.6 parts, "BYK-333" (trade name, manufactured by BYK-Chemie, surface conditioner (polyether-modified polydimethylsiloxane), solid content concentration 100%) 0.1 parts, "TINUVIN 1.2 parts of "TINUVIN 400" (trade name, manufactured by BASF Corporation, triazine-based ultraviolet absorber, solids concentration 85%), 2.0 parts of "TINUVIN 292" (trade name, manufactured by BASF Corporation, hindered amine compound light stabilizer, solids concentration 100%), and 0.6 parts of "NEOSTAN U-830" (trade name, manufactured by Nitto Kasei Co., Ltd., dioctyltin diversatate, solids concentration 100%) were blended and mixed uniformly to obtain Coating Composition No. 1 with a solids concentration of 99.9%.

[0138] Examples 2 to 38 and Comparative Examples 1 to 11 Coating compositions No. 2 to No. 49 were obtained in the same manner as in Example 1, except that the blending compositions in Example 1 were as shown in Table 1 below.

[0139] [Measurement of the molar ratio of uretdione groups and allophanate groups in polyisocyanate composition (B)] The molar ratios of uretdione groups and allophanate groups were measured according to the following method for the polyisocyanate compositions (B) in coating compositions No. 1 to No. 49 obtained in Examples 1 to 38 and Comparative Examples 1 to 11. The results are also shown in Table 1. In the tables, the term "molar ratio of uretdione groups" refers to the molar ratio of uretdione groups to the sum of uretdione groups and allophanate groups in the polyisocyanate composition (B) and isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups present in the polyisocyanate composition (B), and the term "molar ratio of allophanate groups" refers to the molar ratio of allophanate groups to the sum of uretdione groups and allophanate groups in the polyisocyanate composition (B) and isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups present in the polyisocyanate composition (B).

[0140] (Measurement conditions) １３ C-NMR device: JNM-ECZ400R / S1 (manufactured by JEOL), resonance frequency: 100MHz, concentration: 60wt / vol%, shift standard: CDCl ３ (77 ppm), Number of accumulations: 10,000, Pulse program: complete proton decoupling method, Waiting time: 2 seconds, (Characteristic peaks (chemical shift values) of (B) in polyisocyanate composition) Isocyanurate group: 148.5 ppm: integral value ÷ 3 Urethane group: 156.3 ppm: integral value ÷ 1 Allophanate group: around 154 ppm: integral value ÷ 1 Biuret group: 155.8 ppm: (integral value - allophanate group integral value) ÷ 2 Iminooxadiazinedione group: 137.3 ppm: integral value ÷ 1 Uretdione group: 157.5 ppm: integral value ÷ 2.

[0141]

[0142]

[0143]

[0144]

[0145] The components listed in the table are as follows: (Note 1) "FLEXOREZ 188": Trade name, manufactured by KING INDUSTRIES, polyester resin having two hydroxyl groups and an alicyclic skeleton, number average molecular weight 490, solid content 100%, (Note 2) "MPD": Trade name, manufactured by Kuraray Co., Ltd., polyester resin having two hydroxyl groups and no alicyclic skeleton, 3-methyl-1,5-pentanediol, molecular weight 118, solid content 100%, (Note 3) "Kuraray Polyol P-2010": Trade name, manufactured by Kuraray Co., Ltd., polyester resin having two hydroxyl groups and no alicyclic skeleton, number average molecular weight 2000, solid content 100%, (Note 4) "Kuraray Polyol P-510": Trade name, manufactured by Kuraray Co., Ltd., polyester resin having two hydroxyl groups and no alicyclic skeleton, number average molecular weight 500, solid content 100%, (Note 5) "Placcel 205U": Trade name, manufactured by Daicel Corporation, polycaprolactone resin having two hydroxyl groups and no alicyclic skeleton, number average molecular weight 530, solid content 100%, (Note 6) "ETERNACOLL PH-50": Trade name, manufactured by UBE Corporation, polycarbonate resin having two hydroxyl groups and no alicyclic skeleton, number average molecular weight 500, solid content 100%, (Note 7) "Sannix PP-400": Trade name, manufactured by Sanyo Chemical Industries, Ltd., polyether resin having two hydroxyl groups and no alicyclic skeleton, number average molecular weight 400, solid content 100%, (Note 8) "Placcel 303" (Trade name, manufactured by Daicel Corporation, polycaprolactone resin having more than two hydroxyl groups and no alicyclic skeleton, number average molecular weight 310, solid content 100%) (Note 9) "Desmophen NH1220": Trade name, manufactured by Covestro, N,N'-(2-methylpentane-1,5-diyl)bisaspartate tetraethyl, a compound having two secondary amino groups and no alicyclic skeleton, number average molecular weight 461, solid content 100%, (Note 10) "Desmophen NH1423": Trade name, manufactured by Covestro, N,N'-[methylenebis(cyclohexane-4,1-diyl)]bisaspartic acid tetraethyl ester, a compound having two secondary amino groups and an alicyclic skeleton, number average molecular weight 555, solid content 100%, (Note 11) "TMMP-LV": trade name, manufactured by SC Organic Chemical Co., Ltd., trimethylolpropane tris(3-mercaptopropionate), a compound having more than two primary thiol groups and no alicyclic skeleton, number average molecular weight 399, solid content 100%, (Note 12) "Desmodur N3900" polyisocyanate having an iminooxadiazinedione group, solid content 100%, (Note 13) "Desmodur N3600": trade name, manufactured by Sumika Covestro Urethane Co., Ltd., polyisocyanate having an isocyanurate group, solid content 100%.

[0146] [Preparation of In-Mold Coated Molded Product] Example 39 (Preparation of In-Mold Coated Molded Product (M1)) First, "DIALAC TW20" (trade name, manufactured by Techno UMG, acrylonitrile-styrene-acrylate resin (ASA resin)) was filled into an injection molding cylinder and heated to melt at 230°C. Thereafter, it was injected between a resin molding die at 60°C, and the pressure was maintained for 30 seconds while cooling, thereby obtaining a 100 mm x 100 mm x 2 mm flat "DIALAC TW20" molded product. Next, the resin molding die was opened once, and the coating composition No. obtained in Example 1 was inserted between the obtained flat "DIALAC TW20" molded product and the coating film-coated die. 1 was poured into the coating film-coated mold, the inside of the coating film-coated mold was heated to 80°C, and while maintaining the temperature, a molding pressure of 5 MPa was applied and maintained for 1 minute, after which the pressure was reduced and the coating film-coated mold was opened to produce an in-mold coated molding (M1-1) in which a coating film with a cured film thickness of 200 μm was coated on a flat "DIALAC TW20" molding.

[0147] (Preparation of in-mold coated molded product (M2)) First, "Makroblend UT235M" (trade name, manufactured by Covestro, a polymer alloy of polyethylene terephthalate resin and polycarbonate resin) was filled into an injection molding cylinder and heated to melt at 270°C. It was then injected between a resin molding die at 70°C, and cooled while maintaining the pressure for 30 seconds to obtain a 100 mm x 100 mm x 2 mm flat "Makroblend UT235M" molded product. Next, the resin molding die was opened once, and the coating composition No. obtained in Example 1 was inserted between the obtained flat "Makroblend UT235M" molded product and the coating film-coated die. 1 was injected, the inside of the coating film-coated mold was heated to 80°C, and while maintaining the temperature, a molding pressure of 5 MPa was applied and maintained for 1 minute, after which the pressure was reduced and the coating film-coated mold was opened, thereby producing an in-mold coated molding (M2-1) in which a coating film with a cured film thickness of 200 μm was coated on a flat "Makroblend UT235M" molding.

[0148] Examples 40 to 79, Comparative Examples 12 to 22 In-mold coated moldings (M1-2) to (M1-52) and (M2-2) to (M2-52) were prepared in the same manner as in Example 39, except that the type of coating composition and the cured film thickness were as shown in Table 2 below.

[0149] [Evaluation of in-mold coated moldings] The cured coating film on each of the in-mold coated moldings was evaluated for stain resistance, scratch recovery, smoothness and mold releasability. The evaluation results are shown in Table 2.

[0150] (Stain Resistance) A mixture of white petrolatum (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 10% carbon black FW-200 (trade name, manufactured by Orion Engineered Carbons, carbon black pigment, solid content concentration 100%) was applied to the surface of each of the in-mold coated moldings obtained in Examples 39 to 79 and Comparative Examples 12 to 22 in an amount of approximately 200 g / m. ２The mixture was applied so that the stain would be like this and left at room temperature for 24 hours. The mixture was then wiped off with gauze soaked in toilet soap solution as specified in JIS K3301:2007, and the wiped area was observed to evaluate stain resistance based on the following criteria. An evaluation result of A or B was considered acceptable: A: No staining or almost no staining was observed, and no traces were found; B: Almost no staining was observed, but slight traces were found; C: Staining remained.

[0151] (Scratch recovery) The surface of each of the in-mold coated moldings obtained in Examples 39 to 79 and Comparative Examples 12 to 22 was scratched using a scratch tester "Scoot" (manufactured by Profid Co., Ltd.) under the conditions of a scratch load of 15 N, a scratch speed of 10 mm / sec, and a scratch distance of 50 mm, using a SUS scratch indenter (spherical tip φ=1.0 mm). Immediately thereafter, the maximum depth of the scratch was measured using a surface roughness measuring instrument "Surfcom 130A" (manufactured by Tokyo Seimitsu Co., Ltd.). This was designated as d ０ Each of the above in-mold coated moldings was left to stand in an environment of 23°C for 24 hours, and the maximum depth of the scratch was measured in the same manner. １ The scratch recovery rate was calculated using the following formula and evaluated according to the following criteria. If the evaluation result was A or B, it was considered to be acceptable. Scratch recovery rate (%) = (d ０ -d １ ) / d ０ x 100 A: Wound recovery rate is 80% or more, B: Wound recovery rate is 60% or more but less than 80%, C: Wound recovery rate is less than 60%.

[0152] (Smoothness) For each of the in-mold coated moldings obtained in Examples 39 to 79 and Comparative Examples 12 to 22, smoothness was evaluated according to the following criteria based on the Long Wave (LW) value measured using a "Wave Scan" (trade name, manufactured by BYK Gardner). The smaller the LW value, the higher the smoothness of the coated surface, and A and B were rated as passing. A: LW value less than 15, B: LW value 15 or more but less than 18, C: LW value 18 or more.

[0153] (Mold Releasability) In producing the in-mold coated moldings (M1) and (M2), when the coating film coated mold was released, a spatula was inserted into the gap between one of the four corners of the in-mold coated molding and the coating film coated mold, and the mold was lifted up to conduct a mold release test to determine whether the in-mold coated molding could be released from the coating film coated mold. If the mold did not release, the spatula was removed, and the spatula was again inserted into the gap between one of the four corners on the right and the coating film coated mold, and the mold was lifted up in the same way to conduct a mold release test. This was repeated for all four corners until the mold was released, for a total of up to four times. In addition, for in-mold coated moldings where the coating film had peeled off, the surface of the in-mold coated molding was observed with the naked eye, the number of peeled coating film points was counted, and the mold releasability was evaluated according to the following criteria. A and B are acceptable. A: The in-mold coated molded product was released from the mold in the 1st or 2nd mold release test, and the coating film did not peel off; B: The in-mold coated molded product was released from the mold in the 3rd or 4th mold release test, and the coating film did not peel off or the peeling score was 1 point; C: The in-mold coated molded product was released from the mold in the 1st to 4th mold release test, and the coating film peeled off by 2 points or more; D: The in-mold coated molded product did not release from the mold even after 4 mold release tests, or the coating film completely peeled off from the substrate.

[0154]

[0155]

[0156]

[0157]

Claims

1. A coating composition comprising an isocyanate-reactive group-containing compound (A) and a polyisocyanate composition (B), having a solids concentration of 90 mass% or more, wherein the polyisocyanate composition (B) has uretdione groups and allophanate groups, and the molar ratio of the uretdione groups to the total of the uretdione groups and allophanate groups in the polyisocyanate composition (B) and the isocyanurate groups, urethane groups, biuret groups, and iminooxadiazinedione groups present in the polyisocyanate composition (B) is within the range of 5 to 25%. a molar ratio of the allophanate groups to the total of the uretdione groups and allophanate groups in the polyisocyanate composition (B), and the isocyanurate groups, the urethane groups, the biuret groups, and the iminooxadiazinedione groups present in the polyisocyanate composition (B), is within the range of 5 to 55%.

2. The coating composition of claim 1, wherein the isocyanate-reactive group-containing compound (A) comprises an isocyanate-reactive group-containing compound having two isocyanate-reactive groups.

3. The coating composition according to claim 1 or 2, wherein the isocyanate-reactive group-containing compound (A) comprises an isocyanate-reactive group-containing compound having a number average molecular weight in the range of 300 to 1,000.

4. The coating composition according to any one of claims 1 to 3, wherein the isocyanate-reactive group-containing compound (A) comprises an isocyanate-reactive group-containing compound having an alicyclic skeleton.

5. The coating composition according to any one of claims 1 to 4, further comprising a carbodiimide group-containing compound (C).

6. An in-mold coating method comprising the steps of injecting an in-mold coating paint composition between a molded substrate and the inner wall of a mold, curing the in-mold coating paint composition, and then removing the coated molded article from the mold, wherein the in-mold coating paint composition is a paint composition according to any one of claims 1 to 5.

7. The in-mold coating method according to claim 6, wherein the coating film formed by the in-mold coating composition has a dry thickness within the range of 70 to 1000 μm.

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