Coating material composition and in-mold coating method

Abstract

The present invention addresses the problem of providing a coating material composition which has a low VOC content and which can form a coating film having excellent hardness, water resistance, weathering resistance and pinhole resistance. The present invention provides a coating material composition which contains: (A) a main agent containing a hydroxyl group-containing acrylic resin composition that includes (a1) a hydroxyl group-containing acrylic resin and (a2) a polyhydric alcohol; and (B) a curing agent containing a polyisocyanate compound. The hydroxyl group-containing acrylic resin (a1) is synthesized using a solution polymerization method. A solution used in the solution polymerization method contains the polyhydric alcohol (a2).

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, in order to impart excellent appearance, performance, and the like to a substrate surface, a coating film has been formed by applying a coating composition to the substrate surface and curing the resulting wet coating film. From the perspective of reducing the environmental load, there has been a demand for a reduction in volatile organic compounds (VOCs) in the coating composition and a reduction in the air conditioning energy required during painting.

[0003] In recent years, in various technical fields, there has been a demand for high water resistance (water-resistant adhesion and water-whitening resistance) of coating films in addition to high hardness of the coated surface of a substrate.

[0004] Furthermore, when the coating composition is applied to an article to be used outdoors, it is generally required that the composition be capable of forming a coating film having high weather resistance.

[0005] Furthermore, it is known that thermosetting paints can develop a phenomenon called "popping" in the cured coating film formed during the heat curing process, and it is therefore necessary to form coating films with good popping resistance. Popping is a bubble-like coating defect on the surface of the coating film, where the solvent remaining inside the coating film rapidly evaporates during heat curing, creating bubbles in the coating film, and at the same time, the resin components in the coating film solidify, causing the bubbles to appear as bubble-like defects in the areas where the bubbles have formed. The popping is also sometimes called a pinhole.

[0006] 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 １optionally 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) ２ or 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.

[0007] Special Publication No. 2020-528103

[0008] With the technology described in Patent Document 1, although the VOC content in the resulting coating composition is low, the hardness, water resistance, weather resistance and blisters resistance of the coating film formed may not be sufficient.

[0009] An object of the present invention is to provide a coating composition that is capable of forming a coating film that is excellent in hardness, water resistance, weather resistance, and blisters resistance, and that has a low VOC content.

[0010] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that the above-mentioned object can be achieved by a coating composition containing (A) a base agent containing a hydroxyl-containing acrylic resin composition containing (a1) a hydroxyl-containing acrylic resin and (a2) a polyhydric alcohol, and (B) a curing agent containing a polyisocyanate compound, wherein the hydroxyl-containing acrylic resin (a1) is synthesized by a solution polymerization method, and the solution used in the solution polymerization method contains a polyhydric alcohol (a2).

[0011] That is, in a typical embodiment, the present invention relates to the following items <1> to <5>. <1> A coating composition containing (A) a base containing a hydroxyl-containing acrylic resin composition containing (a1) a hydroxyl-containing acrylic resin and (a2) a polyhydric alcohol, and (B) a curing agent containing a polyisocyanate compound, wherein the hydroxyl-containing acrylic resin (a1) is synthesized by solution polymerization, and the solution used in the solution polymerization contains a polyhydric alcohol (a2). <2> The coating composition according to <1>, wherein the polyhydric alcohol (a2) has a melting point within the range of 10 to 150°C. <3> The coating composition according to <1> or <2>, wherein the number-average molecular weight of the polyhydric alcohol (a2) is 1,000 or less. <4> The coating composition according to any one of <1> to <3>, wherein the solids concentration is 90% by mass or more. <5> 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 according to any one of <1> to <4>.

[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 hardness, water resistance, weather resistance, and blisters resistance, 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] The coating composition of the present invention is a coating composition containing (A) a base agent containing a hydroxyl-containing acrylic resin composition containing (a1) a hydroxyl-containing acrylic resin and (a2) a polyhydric alcohol, and (B) a curing agent containing a polyisocyanate compound, wherein the hydroxyl-containing acrylic resin (a1) is synthesized by a solution polymerization method, and the solution used in the solution polymerization method contains the polyhydric alcohol (a2).

[0015] [Base Component Containing Hydroxyl-Containing Acrylic Resin Composition (A)] The base component of the coating composition of the present invention contains a hydroxyl-containing acrylic resin composition (A).

[0016] [Hydroxyl-Containing Acrylic Resin Composition (A)] The hydroxyl-containing acrylic resin composition (A) contains a hydroxyl-containing acrylic resin (a1) and a polyhydric alcohol (a2). The hydroxyl-containing acrylic resin (a1) is synthesized by a solution polymerization method, and the solution used in the solution polymerization method contains the polyhydric alcohol (a2).

[0017] The hydroxyl group-containing acrylic resin (a1) can be obtained, for example, by copolymerizing a hydroxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer (a polymerizable unsaturated monomer other than the hydroxyl group-containing polymerizable unsaturated monomer).

[0018] The hydroxyl group-containing polymerizable unsaturated monomer is a compound having one or more hydroxyl groups and one or more polymerizable unsaturated bonds in one 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; adducts of (meth)acrylic acid with epoxy group-containing compounds (for example, "Cardura E10P" (trade name), manufactured by Momentive Specialty Chemicals, neodecanoic acid glycidyl ester); N-hydroxymethyl (meth)acrylamide; allyl alcohol; and (meth)acrylates having a polyoxyethylene chain whose molecular terminal is a hydroxyl group.

[0019] As the hydroxyl group-containing polymerizable unsaturated monomer, it is preferable to use a primary hydroxyl group-containing polymerizable unsaturated monomer from the viewpoint of the hardness of the coating film to be formed.

[0020] Examples of the primary hydroxyl group-containing polymerizable unsaturated monomer include polymerizable unsaturated monomers having a primary hydroxyl group and in which the alkyl group in the ester moiety has 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. These can be used alone or in combination of two or more. Of these, 2-hydroxyethyl (meth)acrylate is preferred from the viewpoint of the hardness of the coating film to be formed.

[0021] Examples of other polymerizable unsaturated monomers copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer include the following monomers (1) to (6). These polymerizable unsaturated monomers can be used alone or in combination of two or more.

[0022] (1) Acid Group-Containing Polymerizable Unsaturated Monomer The acid group-containing polymerizable unsaturated monomer is a compound having one or more acid groups and one or more polymerizable unsaturated bonds per molecule. Examples of such monomers include carboxyl group-containing monomers such as (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, and maleic anhydride; sulfonic acid group-containing monomers such as vinyl sulfonic acid and 2-sulfoethyl (meth)acrylate; and acidic phosphate ester monomers such as 2-(meth)acryloyloxyethyl acid phosphate, 2-(meth)acryloyloxypropyl acid phosphate, 2-(meth)acryloyloxy-3-chloropropyl acid phosphate, and 2-methacryloyloxyethylphenyl phosphoric acid. These monomers may be used alone or in combination. When an acid group-containing polymerizable unsaturated monomer is used, it is preferably used in an amount such that the acid value of the hydroxyl group-containing acrylic resin (A) is 0.5 to 30 mgKOH / g, particularly 1 to 20 mgKOH / g, from the viewpoint of the water resistance of the coating film.

[0023] When an acid group-containing polymerizable unsaturated monomer is used as a constituent component, the blending ratio thereof is preferably within the range of 0.03 to 7.00 mass %, particularly 0.05 to 5.00 mass %, based on the total amount of the monomer components.

[0024] (2) Esterification products of acrylic acid or methacrylic acid with monohydric alcohols having 1 to 20 carbon atoms. Specific examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, isostearyl acrylate (trade name, manufactured by Osaka Organic Chemical Industry Ltd.), lauryl (meth)acrylate, tridecyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate.

[0025] When an ester of acrylic acid or methacrylic acid with a monohydric alcohol having 1 to 20 carbon atoms is used as a constituent component, the blending ratio thereof is preferably within the range of 10 to 87% by mass, particularly 20 to 70% by mass, based on the total amount of the monomer components.

[0026] (3) Aromatic vinyl monomers Specific examples include styrene, α-methylstyrene, vinyltoluene, and the like.

[0027] By using an aromatic vinyl monomer as a constituent component, the glass transition temperature of the resulting resin is increased, and a coating film with a high refractive index and hydrophobicity can be obtained, which can improve the gloss of the coating film and thereby the finished appearance.

[0028] When an aromatic vinyl monomer is used as a constituent component, the blending ratio thereof is preferably within the range of 3 to 50% by mass, and particularly 5 to 40% by mass, based on the total amount of the monomer components.

[0029] (4) Glycidyl Group-Containing Polymerizable Unsaturated Monomer The glycidyl group-containing polymerizable unsaturated monomer is a compound having one or more glycidyl groups and one or more polymerizable unsaturated bonds in one molecule, and specific examples thereof include glycidyl acrylate and glycidyl methacrylate.

[0030] (5) Polymerizable Unsaturated Bond-Containing Nitrogen Atom-Containing Compounds Examples thereof include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-[3-(dimethylamino)propyl](meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetone(meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylate, vinylpyridine, vinylimidazole, acrylonitrile, and methacrylonitrile.

[0031] (6) Other vinyl compounds Examples include vinyl acetate, vinyl propionate, vinyl chloride, and versatic acid vinyl ester. Examples of versatic acid vinyl ester include commercially available products such as "Veoba 9" and "Veoba 10" (both trade names, manufactured by Japan Epoxy Resin Co., Ltd.).

[0032] As the other polymerizable unsaturated monomers, the monomers shown in (1) to (6) above can be used alone or in combination of two or more.

[0033] In the present invention, the polymerizable unsaturated monomer refers to a monomer having one or more (e.g., 1 to 4) polymerizable unsaturated groups. The polymerizable unsaturated group refers to an unsaturated group that can undergo 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.

[0034] In addition, in this specification, "(meth)acrylate" means acrylate or methacrylate. "(meth)acrylic acid" means acrylic acid or methacrylic acid. "(meth)acryloyl" means acryloyl or methacryloyl. "(meth)acrylamide" means acrylamide or methacrylamide.

[0035] In the production of the hydroxyl-containing acrylic resin (a1), the amount of the hydroxyl-containing polymerizable unsaturated monomer used is preferably within the range of 15 to 50% by mass, more preferably 20 to 40% by mass, based on the total amount of copolymerizable monomer components, from the viewpoints of the water resistance, hardness, and popping resistance of the coating film to be formed.

[0036] The hydroxyl value of the hydroxyl-containing acrylic resin (a1) is preferably within the range of 50 to 210 mgKOH / g, particularly 80 to 200 mgKOH / g, and more particularly 100 to 190 mgKOH / g, from the viewpoint of the water resistance and hardness of the coating film to be formed.

[0037] The hydroxyl group-containing acrylic resin (a1) is synthesized by a solution polymerization method, and the solution used in the solution polymerization method contains a polyhydric alcohol (a2).

[0038] The polyhydric alcohol (a2) 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.

[0039] From the viewpoint of the hardness and water resistance of the coating film to be formed, the melting point of the polyhydric alcohol (a2) is preferably in the range of 10 to 150°C, more preferably in the range of 15 to 145°C, and even more preferably in the range of 20 to 140°C.

[0040] In this specification, the melting point is measured by differential scanning calorimetry (DSC) using a differential scanning calorimeter.

[0041] Examples of the polyhydric alcohol (a2) having a melting point in the range of 10 to 150°C include dihydric alcohols such as 1,4-butanediol, 2,3-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 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, hydroxypivalic acid neopentyl glycol ester, and isosorbide; Examples include polylactone diols obtained by adding a lactone compound such as ε-caprolactone to coal; 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, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, tris(2-hydroxyethyl)isocyanuric acid, and sorbitol; 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.

[0042] Furthermore, from the viewpoints of providing a coating composition with high hardness, water resistance, and anti-fouling properties of the coating film formed, as well as a low VOC content, the polyhydric alcohol (a2) preferably has a number average molecular weight of 1,000 or less, more preferably in the range of 50 to 1,000, and even more preferably in the range of 100 to 800.

[0043] Examples of the polyhydric alcohol (a2) having a number average molecular weight of 1,000 or less 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, and 3-methyl-1,5-pentanediol. ethanol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydroxypivalic acid neopentyl glycol ester, hydrogenated bisphenol A, dimethylolpropionic acid, isosorbide, glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tris(2-hydroxyethyl)isocyanuric acid, sorbitol, mannitol, and the like.

[0044] Furthermore, from the viewpoints of providing a coating composition with good hardness, water resistance, and anti-flaking properties of the coating film formed, and a low VOC content, it is preferable that the polyhydric alcohol (a2) has a melting point in the range of 10 to 150°C and a number average molecular weight of 1,000 or less.

[0045] Examples of the polyhydric alcohol (a2) having a melting point in the range of 10 to 150°C and a number average molecular weight of 1000 or less include 1,4-butanediol, 2,3-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-pentanediol, 2,4-pentanediol, tetramethylene glycol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, and 1,5-hexanediol. Examples of the alcohol include dihydric alcohols such as ethanol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, hydroxypivalic acid neopentyl glycol ester, and isosorbide; and trihydric or higher alcohols such as glycerin, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, tris(2-hydroxyethyl)isocyanuric acid, and sorbitol.

[0046] The polyhydric alcohols (a2) can be used alone or in combination of two or more kinds.

[0047] From the viewpoints of providing a coating composition with high hardness, water resistance, weather resistance, and anti-flake properties for the coating film to be formed, as well as a low VOC content, the amount of the polyhydric alcohol (a2) blended 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 (a1).

[0048] The solution used in the solution polymerization method may contain an organic solvent other than the polyhydric alcohol (a2) as needed.

[0049] 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.

[0050] When an organic solvent is contained during the solution polymerization, the content thereof is preferably 80 mass% or less, more preferably 70 mass% or less, and even more preferably 60 mass% or less, based on the total amount of the polyhydric alcohol (a2) (the total amount of the polyhydric alcohol (a2) being 100 mass%).

[0051] In the solution polymerization, it is preferable to use a polymerization initiator.

[0052] Examples of the polymerization initiator include known radical polymerization initiators such as 2,2'-azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, di-t-amyl peroxide, t-butyl peroctoate, 2,2'-azobis(2-methylbutyronitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile).

[0053] In a preferred embodiment of the present invention, the (a1) hydroxyl-containing acrylic resin can be obtained by polymerizing raw material monomers for the (a1) hydroxyl-containing acrylic resin (preferably, a hydroxyl-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers) in a solution containing the (a2) polyhydric alcohol and, optionally, other components. In this embodiment, the temperature during solution polymerization is not limited, but can be appropriately set, for example, within the range of 100 to 190°C, preferably 110 to 150°C. The solution polymerization time is also not limited, but can be appropriately set, for example, within the range of 1 to 6 hours, preferably 2 to 4 hours.

[0054] The number average molecular weight of the hydroxyl group-containing acrylic resin (a1) is preferably within the range of 1,000 to 3,000, more preferably within the range of 1,200 to 2,800, and even more preferably within the range of 1,500 to 2,500, from the viewpoints of providing a coating composition with low VOC content, as well as the hardness, water resistance, weather resistance, and flake resistance of the coating film to be formed.

[0055] In this specification, the average molecular weight is a value calculated from a chromatogram measured by gel permeation chromatography using the molecular weight of standard polystyrene as a reference. The gel permeation chromatograph used was "HLC8120GPC" (manufactured by Tosoh Corporation). Four columns, "TSKgel G-4000HXL," "TSKgel G-3000HXL," "TSKgel G-2500HXL," and "TSKgel G-2000HXL" (all manufactured by Tosoh Corporation, trade names), were used, and the measurement was performed under the following conditions: mobile phase: tetrahydrofuran, measurement temperature: 40°C, flow rate: 1 cc / min, and detector: RI.

[0056] The glass transition temperature of the hydroxyl group-containing acrylic resin (a1) is preferably within the range of 0 to 90°C, more preferably within the range of 10 to 80°C, and even more preferably within the range of 20 to 70°C, from the viewpoints of the hardness, water resistance, weather resistance, and flake resistance of the coating film to be formed, and of providing a coating composition with a low VOC content.

[0057] In this specification, the glass transition temperature (°C) of the acrylic resin was calculated by the following formula.

[0058] 1 / Tg(K)=(W1 / T1)+(W2 / T2)+... (1) Tg(°C)=Tg(K)-273 (2) In each formula, W1, W2,... represent the mass fraction of each monomer used in copolymerization, and T1, T2,... represent the Tg(K) of the homopolymer of each monomer. Note that T1, T2,... are values ​​according to pages III-139 to 179 of Polymer Hand Book (Second Edition, edited by J. Brandup and E.H. Immergut). When the Tg of the homopolymer of the monomer is unclear, the glass transition temperature (°C) is taken as the static glass transition temperature. For example, a differential scanning calorimeter "DSC-220U" (manufactured by Seiko Instruments Inc.) is used. A sample is placed in a measuring cup, and the solvent is completely removed by vacuum suction. Then, the change in calorific value is measured in the range of -20°C to +200°C at a heating rate of 3°C / min, and the first change point in the baseline on the low temperature side is taken as the static glass transition temperature.

[0059] In the present invention, the hydroxyl-containing acrylic resin composition (A) contains (a1) a hydroxyl-containing acrylic resin and (a2) a polyhydric alcohol. In one embodiment, the hydroxyl-containing acrylic resin composition (A) may be a reaction solution obtained by solution polymerization of the hydroxyl-containing acrylic resin (a1) using a solution containing the polyhydric alcohol (a2). The hydroxyl-containing acrylic resin composition (A) may be used alone or in combination of two or more kinds.

[0060] The content of the hydroxyl group-containing acrylic resin composition (A) in the main component of the coating composition of the present invention is preferably within the range of 40 to 100 mass %, more preferably 45 to 90 mass %, and even more preferably 50 to 80 mass %, based on the total amount of the main component of the coating composition, from the viewpoints of providing a coating film having good hardness, water resistance, weather resistance, and flake resistance, as well as a coating composition with a low VOC content.

[0061] Furthermore, from the viewpoints of providing a coating composition with good hardness, water resistance, weather resistance and flake resistance of the coating film to be formed, and with a low VOC content, the content of the hydroxyl group-containing acrylic resin composition (A) in the coating composition of the present invention is preferably within the range of 10 to 50 mass %, more preferably 12 to 40 mass %, and even more preferably 14 to 35 mass %, based on the total amount of the coating composition.

[0062] [Other Components] The main component of the coating composition of the present invention may further contain an ultraviolet absorber and / or a light stabilizer in addition to the above. Furthermore, if necessary, other additive components commonly used in the field of coating, such as an isocyanate-reactive group-containing compound other than the hydroxyl group-containing acrylic resin composition (A), a solvent, 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, a gloss adjuster, etc., may be appropriately contained.

[0063] 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. The ultraviolet absorber may also have a polymerizable unsaturated group.

[0064] 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.

[0065] 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.

[0066] Specific examples of the salicylic acid derivative-based absorbents include phenyl salicylate, p-octylphenyl salicylate, and 4-tert-butylphenyl salicylate.

[0067] 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.

[0068] 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.).

[0069] When the main component of the coating composition of the present invention contains the above-mentioned ultraviolet absorber, the content of the ultraviolet absorber is preferably in the range of 0.5 to 10 mass %, more preferably in the range of 0.8 to 5.0 mass %, and even more preferably in the range of 1.0 to 4.0 mass %, based on the total amount of the main component of the coating composition, from the viewpoint of the weather resistance of the coating film to be formed, etc.

[0070] 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.

[0071] 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, monomeric types such as methyl acrylate; oligomeric types such as poly{[6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)iminol]}; and polyester bond types such as a polyesterification product of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and succinic acid, but are not limited to these. Also, known light stabilizers can be used as the light stabilizer.

[0072] Examples of commercially available products of the light stabilizer include "TINUVIN 123", "TINUVIN 152", "TINUVIN 249", and "TINUVIN 292" (trade names, manufactured by BASF, TINUVIN is a registered trademark), "HOSTAVIN 3058" (trade name, manufactured by Clariant, Hostavin is a registered trademark), and "ADK STAB LA-82" (trade name, manufactured by ADEKA Corporation, ADK STAB is a registered trademark).

[0073] When the main component of the coating composition of the present invention contains the above-mentioned light stabilizer, the content of the light stabilizer is preferably in the range of 0.5 to 10 mass %, more preferably in the range of 0.8 to 9.0 mass %, and even more preferably in the range of 1.0 to 8.0 mass %, based on the total amount of the main component of the coating composition, from the viewpoint of the weather resistance of the coating film to be formed, etc.

[0074] Examples of the isocyanate-reactive group-containing compound other than the hydroxyl group-containing acrylic resin composition (A) include hydroxyl group-containing compounds other than the hydroxyl group-containing acrylic resin composition (A), amino group-containing compounds, and thiol group-containing compounds.

[0075] The hydroxyl group-containing compound is a compound having at least one hydroxyl group per molecule. Examples of the hydroxyl group-containing compound include 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 other than the hydroxyl group-containing acrylic resin (a1), hydroxyl group-containing polyurethane resins, hydroxyl group-containing epoxy resins, and hydroxyl group-containing alkyd resins. Among these, hydroxyl group-containing polycaprolactone resins are preferred.

[0076] 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 compounds can be used alone or in combination of two or more.

[0077] 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 0201'', ``TONE 0230'', ``TONE 0249'', ``TONE 0301'', ``TONE 0305'', ``TONE 0310'', ``TONE 1241'', ``TONE 1278'', ``TONE 2221'' (the above, product name, The Dow Chemical), "Capa 2043", "Capa 2101", "Capa 2201", "Capa 2205", "Capa 2209", "Capa 2201A", "Capa 2203A", "Capa 7201A", "Capa 7203'', ``Capa 3031'', ``Capa 3050J'', ``Capa 3091'', ``Capa 4101" (trade name, manufactured by Ingevity Inc.) and the like.

[0078] From the viewpoint of the water resistance and hardness of the coating film to be formed, the hydroxyl value of the hydroxyl group-containing polycaprolactone resin is preferably within a range of 50 to 900 mgKOH / g, more preferably within a range of 100 to 750 mgKOH / g, and even more preferably within a range of 130 to 600 mgKOH / g.

[0079] The number average molecular weight of the hydroxyl group-containing polycaprolactone resin is preferably within the range of 200 to 5,000, more preferably within the range of 250 to 3,000, and even more preferably within the range of 300 to 2,000, from the viewpoints of reducing the VOC content in the resulting coating composition and improving the water resistance and hardness of the coating film formed.

[0080] When the main ingredient of the coating composition of the present invention contains a hydroxyl group-containing polycaprolactone resin, the content of the hydroxyl group-containing polycaprolactone resin is preferably in the range of 1 to 50 mass %, more preferably in the range of 5 to 48 mass %, and even more preferably in the range of 10 to 46 mass %, based on the total amount of the main ingredient of the coating composition, from the viewpoints of providing a coating film with good hardness, water resistance, weather resistance, and popping resistance, as well as a coating composition with a low VOC content.

[0081] The amino group-containing compound is a compound having at least one primary amino group and / or secondary amino group in the molecule.

[0082] Examples of the amino group-containing compound 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, 1,4-cyclohexanediamine, 4-methyl-1,3-cyclohexanediamine, 2-methyl-1,3- Alicyclic polyamines such as 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(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, and norbornanediamine; pipera heterocyclic polyamines such as 2,4-toluenediamine, 2,6-toluenediamine, 4,4'-diaminodiphenylmethane, diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-methylenebis[N-(1-methylpropyl)aniline], 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 4,4'-(1,3-phenylenediisopropyl)aniline, 1,3-bis(3-aminophenoxy)benzene, 1,3-phenylenediisopropyl aromatic polyamines such as 4,4'-(1,4-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 polyoxypropylenediamine, polyoxyethylenediamine, poly(oxyethylene / oxypropylene)diamine, trimethylolpropanepoly(oxypropylene)triamine, and glycerylpoly(oxypropylene)triamine;Examples of suitable polyaspartic acid ester compounds include tetraethyl N,N'-(2-methylpentane-1,5-diyl)bisaspartate, tetraethyl N,N'-[methylenebis(cyclohexane-4,1-diyl)]bisaspartate, tetraethyl N,N'-[methylenebis(2-methylcyclohexane-4,1-diyl)]bisaspartate, 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 compounds can be used alone or in combination of two or more.

[0083] The thiol group-containing compound is a compound having at least one thiol group in one molecule.

[0084] Examples of the thiol group-containing compound 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 hexakis(3-mercaptopropionate), trimethylolpropane dipropanethiol, and pentaerythritol hexakis(3-mercaptopropionate). Examples of such esters include trimethylolpropane triol, pentaerythritol tetrapropane triol, 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), and pentaerythritol tetrakis(thioglycolate). These may be used alone or in combination of two or more.

[0085] Examples of the solvent that can be used include organic solvents, such as 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.

[0086] The content of the above solvent in the main component of the coating composition of the present invention is preferably 15 mass % or less based on the total amount of the main component of the coating composition, from the viewpoint of providing a coating composition that has good resistance to foaming and a low VOC content.

[0087] Examples of the pigment include luster pigments, color pigments, extender pigments, etc. The pigments may be used alone or in combination of two or more.

[0088] Examples of the bright pigment 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.

[0089] Examples of the color pigment 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.

[0090] Examples of the extender pigment include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white.

[0091] When the main component of the coating composition of the present invention contains the above-mentioned pigment, the content of the pigment is preferably in the range of 0.1 to 60 mass %, more preferably in the range of 0.2 to 55 mass %, and even more preferably in the range of 0.3 to 50 mass %, based on the total amount of the main component of the coating composition, from the viewpoints of providing a coating film having high hardness, water resistance, weather resistance, and flake resistance, as well as a coating composition with a low VOC content.

[0092] In the present invention, the pigment may be prepared as a pigment paste separately from the base resin and the curing agent to form a so-called three-component coating composition.

[0093] Examples of the catalyst include tin octylate, 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 octylate, 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'',N''-pentamethyldiethylenetriamine, N,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]-2-methylpropanediol (DABCO), 1,8-diazabicyclo[5.4.0]-2-methylpropanediol ... tertiary amine compounds such as 1,3-dimethyl-2,4 ...

[0094] When the main component of the coating composition of the present invention contains the above catalyst, from the viewpoints of providing a coating film having high hardness, water resistance, weather resistance and popping resistance, as well as a coating composition with a low VOC content, the amount of catalyst blended is preferably in the range of 0.01 to 5.0 mass%, more preferably in the range of 0.05 to 4.0 mass%, and even more preferably in the range of 0.1 to 3.0 mass%, based on the total amount of the main component of the coating composition.

[0095] Furthermore, when the main ingredient of the coating composition of the present invention contains the above 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 compounds.

[0096] As the dehydrating agent, conventionally known inorganic dehydrating agents and organic dehydrating agents can be used.

[0097] 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 may be used alone or in combination of two or more.

[0098] 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. These can be used alone or in combination of two or more.

[0099] When the main ingredient of the coating composition of the present invention contains the above-mentioned dehydrating agent, from the viewpoints of providing a coating film having high hardness, water resistance, weather resistance and flake resistance, as well as a coating composition with a low VOC content, the amount of the dehydrating agent blended 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 0.3 to 3.0 mass%, based on the total amount of the main ingredient of the coating composition.

[0100] The viscosity of the base material of the coating composition of the present invention is determined from the viewpoints of providing a coating composition with high hardness, water resistance, weather resistance, and anti-flaking properties of the coating film formed, as well as a low VOC content, at a temperature of 65°C and a shear rate of 100 sec. －１ The viscosity at 2000 to 3000 mPa·s is preferably in the range of 20 to 3000 mPa·s, more preferably in the range of 100 to 2800 mPa·s, and even more preferably in the range of 200 to 2500 mPa·s.

[0101] The method for measuring viscosity will be explained in the examples.

[0102] [Curing Agent Containing Polyisocyanate Compound (B)] The curing agent for the coating composition of the present invention contains a polyisocyanate compound (B).

[0103] [Polyisocyanate Compound (B)] The polyisocyanate compound (B) is a compound having at least two isocyanate groups in one molecule, and includes, for example, aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of the polyisocyanates.

[0104] 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 (common name: lysine diisocyanate), diisocyanato), and the like; and aliphatic triisocyanates 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] Examples of the polyisocyanate derivatives include dimers, trimers, biurets, allophanates, uretdione, uretonimine, isocyanurates, iminooxadiazinedione, polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI), crude TDI, and the like of the above-mentioned polyisocyanate compounds.

[0109] The polyisocyanates and derivatives thereof may be used alone or in combination of two or more thereof. Among these polyisocyanates, it is preferable to use aliphatic diisocyanates, aliphatic triisocyanates, alicyclic diisocyanates, araliphatic diisocyanates, and derivatives thereof alone or in combination of two or more thereof.

[0110] The polyisocyanate compound (B) may be a prepolymer obtained by reacting the polyisocyanate or a derivative thereof with a compound reactive with the polyisocyanate under conditions of excess isocyanate groups. Examples of the compound reactive with the polyisocyanate include compounds having an active hydrogen group such as a hydroxyl group or an amino group, and specific examples of the compound that can be used include polyhydric alcohols, low-molecular-weight polyester resins, amines, and water.

[0111] From the viewpoints of providing a coating composition with high hardness, water resistance, weather resistance and foaming resistance of the coating film formed, as well as a low VOC content, the content of the polyisocyanate compound (B) in the curing agent of the coating composition of the present invention is preferably in the range of 80 to 100 mass %, more preferably in the range of 85 to 98 mass %, and even more preferably in the range of 90 to 96 mass %, based on the total amount of the curing agent in the coating composition.

[0112] Furthermore, from the viewpoints of providing a coating composition with high hardness, water resistance, and weather resistance of the coating film to be formed, as well as a low VOC content, the content of the polyisocyanate compound (B) in the coating composition of the present invention 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.

[0113] [Other Components] In addition to the above, the curing agent of the coating composition of the present invention may further contain a curing agent other than the polyisocyanate compound (B). If necessary, it may also contain other additives commonly used in the field of coating, such as hydrolysis stabilizers, UV absorbers, light stabilizers, internal mold release agents, solvents, pigments, catalysts, dehydrating agents, antioxidants, surface conditioners, antifoaming agents, emulsifiers, surfactants, antifouling agents, wetting agents, thickeners, dyes, scratch resistance improvers, gloss adjusters, etc.

[0114] The hydrolysis stabilizer may include, for example, a carbodiimide group-containing compound.

[0115] The carbodiimide group-containing compound is a compound having at least one carbodiimide group in one molecule, and can be, for example, a compound obtained by subjecting the isocyanate groups of an isocyanate group-containing compound to a carbon dioxide-eliminating reaction.

[0116] Commercially available products can be used as the carbodiimide group-containing compound. Examples of commercially available products with trade names include "Carbodilite V-02B," "Elastostab H01," "Carbodilite V-03," "Carbodilite V-05," "Carbodilite V-09," "Carbodilite V-09GB," "Carbodilite V-09M," and "Carbodilite V-04PF" (all trade names, manufactured by Nisshinbo Chemical Inc.), "Stabaxol I," "Stabaxol I LF," "Stabaxol P," "Stabaxol P100," and "Stabaxol P200" (all trade names, manufactured by LANXESS).

[0117] The number average molecular weight of the carbodiimide group-containing compound 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 hardness and water resistance of the coating film to be formed.

[0118] In the present invention, a compound having a carbodiimide group and two or more isocyanate groups is not included in the polyisocyanate compound (B), but is included in the carbodiimide group-containing compound.

[0119] The carbodiimide group-containing compound preferably includes a solvent-free carbodiimide group-containing compound from the viewpoint of reducing the VOC content in the resulting coating composition.

[0120] The solvent-free carbodiimide group-containing compound may be commercially available, such as "Carbodilite V-02B," "Carbodilite V-05," "Elastostab H01," and "Carbodilite V-04PF" (all of which are product names manufactured by Nisshinbo Chemical Inc.).

[0121] When the curing agent of the coating composition of the present invention contains a carbodiimide group-containing compound, the content of the carbodiimide group-containing compound is preferably in the range of 0.5 to 10 mass %, more preferably in the range of 1 to 9 mass %, and even more preferably in the range of 2 to 7 mass %, based on the total amount of the curing agent in the coating composition, from the viewpoints of providing a coating film with good hardness, water resistance, weather resistance, and popping resistance, as well as a coating composition with a low VOC content.

[0122] As the solvent, for example, the solvents exemplified in the description of the main component containing the hydroxyl group-containing acrylic resin composition (A) can be used.

[0123] When the curing agent of the coating composition of the present invention contains the above-mentioned solvent, the content of the solvent is preferably 20 mass % or less, more preferably 15 mass % or less, and even more preferably 10 mass % or less, based on the total amount of the curing agent in the coating composition, from the viewpoints of providing a coating film with good hardness, water resistance, weather resistance, and flake resistance, as well as a coating composition with a low VOC content.

[0124] As the dehydrating agent, for example, the dehydrating agents exemplified in the section explaining the main component containing the hydroxyl group-containing acrylic resin composition (A) can be used.

[0125] When the curing agent of the coating composition contains the above-mentioned dehydrating agent, from the viewpoints of providing a coating film having high hardness, water resistance, weather resistance, and anti-flaking properties, as well as a coating composition with a low VOC content, the amount of the dehydrating agent blended is preferably in the range of 0.1 to 3 mass %, more preferably in the range of 0.3 to 2 mass %, and even more preferably in the range of 0.5 to 1 mass %, based on the total amount of the curing agent in the coating composition.

[0126] The viscosity of the curing agent of the coating composition of the present invention is set to 65°C at a shear rate of 100 sec from the viewpoints of providing a coating composition with high hardness, water resistance, weather resistance, and anti-flaking properties of the coating film to be formed, as well as a low VOC content. －１The viscosity at 2000 to 3000 mPa·s is preferably in the range of 20 to 2000 mPa·s, more preferably in the range of 40 to 2000 mPa·s, and even more preferably in the range of 80 to 1000 mPa·s.

[0127] [Coating composition] The coating composition of the present invention is a coating composition containing (A) a base agent containing a hydroxyl-containing acrylic resin composition containing (a1) a hydroxyl-containing acrylic resin and (a2) a polyhydric alcohol, and (B) a curing agent containing a polyisocyanate compound, wherein the hydroxyl-containing acrylic resin (a1) is synthesized by a solution polymerization method, and the solution used in the solution polymerization method contains a polyhydric alcohol (a2).

[0128] The ratio of the base agent to the curing agent in the coating composition of the present invention is preferably such that the ratio of isocyanate groups in the curing agent to hydroxyl groups in the base agent is within the range of 0.5 to 2.0, more preferably 0.7 to 1.5, from the viewpoint of the hardness, water resistance, weather resistance, and blisters resistance of the coating film to be formed.

[0129] The solids concentration of the coating composition of the present invention is preferably 90% by mass or more, more preferably 93% by mass or more, and even more preferably 97% by mass or more, from the viewpoints of reducing the VOC content in the resulting coating composition and improving the cracking resistance of the coating film formed.

[0130] In this specification, the term "solid content" refers to non-volatile components such as resins, curing agents, and pigments that remain after drying for 30 minutes at 80° C. 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 it at 80° C. for 30 minutes, and weighing the mass of the components remaining after drying.

[0131] In this specification, the term "solid content concentration" refers to the mass ratio of the 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 remaining in the composition after drying, and determining the ratio of the mass of the components remaining after drying to the total mass of the composition before drying.

[0132] The reason why the coating composition of the present invention can provide a coating composition that forms a coating film with high hardness, water resistance, weather resistance, and blisters resistance, as well as a low VOC content, is not clear. However, because the hydroxyl-containing acrylic resin (a1) is synthesized in a solution containing the polyhydric alcohol (a2), the VOC content can be reduced, and the amount of solvent that evaporates is reduced, resulting in good blisters resistance. Furthermore, because the hydroxyl-containing acrylic resin (a1) contains hydroxyl groups, it reacts well with the polyisocyanate compound (B), allowing the formation of a coating film with excellent hardness, water resistance, and weather resistance. Furthermore, it is presumed that the polyhydric alcohol (a2) used in the synthesis of the hydroxyl-containing acrylic resin (a1) also reacts well with the polyisocyanate compound (B), allowing the formation of a coating film with excellent hardness, water resistance, and weather resistance.

[0133] [Method for producing a coating composition or its main component] As described above, the hydroxyl-containing acrylic resin (a1) for use in the main component of the coating composition of the present invention can be synthesized by solution polymerization using a solution containing a polyhydric alcohol (a2). Thus, in one embodiment, the present invention provides a method for producing a hydroxyl-containing acrylic resin (a1) for use in producing a main component of a coating composition, comprising a step of solution polymerization using a solution containing a polyhydric alcohol (a2), wherein the coating composition contains a main component containing a hydroxyl-containing acrylic resin composition containing the hydroxyl-containing acrylic resin (a1) and the polyhydric alcohol (a2), and a curing agent containing a polyisocyanate compound (B). In one embodiment, the present invention provides a method for producing a hydroxyl-containing acrylic resin composition for use as a base agent of a coating composition, the method comprising the step of producing a hydroxyl-containing acrylic resin (a1) by solution polymerization using a solution containing a polyhydric alcohol (a2), wherein the coating composition contains a base agent containing a hydroxyl-containing acrylic resin composition containing the hydroxyl-containing acrylic resin (a1) and the polyhydric alcohol (a2), and a curing agent containing a polyisocyanate compound (B).

[0134] In one embodiment, the present invention provides a method for producing a base agent for a coating composition, the method comprising the steps of: producing a hydroxyl-containing acrylic resin composition by the above method; and optionally, mixing the hydroxyl-containing acrylic resin composition obtained in the above step with components other than the hydroxyl-containing acrylic resin composition.

[0135] Furthermore, in one embodiment, the present invention provides a method for producing a coating composition, comprising the steps of producing a base agent for a coating composition by the above method, and combining the base agent obtained in the step with (B) a curing agent containing a polyisocyanate compound.

[0136] In these methods, the types and amounts of the components (a1) hydroxyl group-containing acrylic resin, (a2) polyhydric alcohol, polyisocyanate compound, etc., the solution polymerization conditions, etc., can be the same as those described above. In the method for producing a coating composition, the step of combining the base agent and curing agent includes not only mixing the base agent and curing agent and curing them, but also combining them while they are filled in separate containers.

[0137] [Method for forming a coating film] The coating composition of the present invention 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.

[0138] The substrate is preferably made of a resin material from the viewpoint of the water resistance of the coating film to be formed.

[0139] 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 suitable resins include lylonitrile-styrene-acrylate (ASA) resins, vinyl chloride resins, vinylidene chloride resins, polyurethane resins, cellulose ester resins (e.g., triacetyl cellulose, diacetyl cellulose, propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose, nitrocellulose), polyamide resins, polystyrene resins (e.g., syndiotactic polystyrene), polyolefin resins (e.g., polypropylene, polyethylene, polymethylpentene), polysulfone resins, polyethersulfone resins, polyarylate resins, polyetherimide resins, polyether ketone resins, various fiber reinforced plastic materials (Fiber Reinforced Plastics: hereinafter sometimes abbreviated as FRP materials or simply FRP), and polymer alloys thereof.

[0140] The substrate may also be one in which, for example, a primer coating, an intermediate coating, a top coating, or the like is applied onto the resin material, thereby forming a primer layer, an intermediate coating layer, a top coating layer, or the like in advance.

[0141] The substrate may be subjected to at least one physical treatment (physical treatment) selected from plasma treatment, corona discharge treatment, active energy ray treatment, flame treatment, blast treatment, polishing treatment, and the like.

[0142] The coating composition of the present invention is preferably applied directly onto a substrate.

[0143] Furthermore, the applications of substrates to which the coating composition of the present invention can be applied are not particularly limited, and examples include outer panels of automobile bodies such as passenger cars, trucks, motorcycles, and buses; interior and exterior automobile 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.

[0144] The method for applying the coating composition of the present invention to a substrate is not particularly limited. For example, the coating composition can be applied by air spray, airless spray, rotary atomizer, dip coating, applicator, brush, roller, in-mold coating, etc. Electrostatic application may be performed during application.

[0145] The coating thickness, in terms of cured film thickness, is preferably within the range of 5 to 2000 μm, more preferably within the range of 10 to 1500 μm, and even more preferably within the range of 15 to 1000 μm.

[0146] The coating composition of the present invention can be cured on a substrate by heating the coating composition.

[0147] The heating can be carried out by any suitable method known in this field. Specifically, for example, hot air, hot gas, an infrared heater, an IR radiator, an oven, a heated roller, a hot press, a microwave, etc. In the present invention, from the viewpoint of ease of operation, etc., it is preferable to carry out heating by hot air, an infrared heater, a hot press, etc.

[0148] From the viewpoints of productivity, workability, thermal stability of the substrate, etc., the heating temperature is preferably within a range of 30 to 200°C, more preferably within a range of 50 to 180°C, and even more preferably within a range of 70 to 160°C.

[0149] 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.

[0150] The coating composition of the present invention can also be suitably used in coating by the in-mold coating method, which has the advantage of being able to use coating compositions with low VOC contents and also reducing the air conditioning energy required during coating, thereby reducing the environmental impact.

[0151] [In-mold coating method] The in-mold coating method according to the present invention comprises the steps of injecting the coating composition of the present invention (hereinafter, when the coating composition of the present invention is used in the in-mold coating method, it will be referred to as the in-mold coating coating composition) between a molded substrate and the inner wall of a mold, curing the in-mold coating coating composition, and then removing the coated molded article from the mold.

[0152] The above-mentioned in-mold coating composition preferably contains an internal mold release agent from the viewpoint of the releasability of the formed coating film from the mold.

[0153] The internal mold release agent is preferably blended into the main component of the coating composition.

[0154] 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;

[0155] From the viewpoints of the water resistance, weather resistance, and water-whitening resistance of the coating film to be formed, as well as the releasability between the coating film to be formed and the mold, the internal release agent preferably contains a fatty acid amide, more preferably contains a fatty acid tertiary amide, and even more preferably contains a fatty acid tertiary dimethylamide.

[0156] Examples of the fatty acid amides include 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; and unsaturated fatty acid amides such as palmitoleic acid amide, oleic acid amide, erucic acid amide, behenic acid amide, N-oleylpalmitic acid amide, N-stearylerucic acid amide, N,N-dimethyloleic acid amide, and N,N-diethyloleic acid amide.

[0157] As the internal mold release agent containing the fatty acid amide, commercially available products can be used. Examples of commercially available product names include "INT-120IMC" (trade names, manufactured by Axel Plastics), "Amide AP-1", "Diamid Y", "Diamid O-200", "Diamid I-200" (trade names, manufactured by Mitsubishi Chemical Corporation), "Neutron", "Neutron-2", "Neutron-S", "Neutron BNT-22H", "Neutron PNT-34", "Neutron SNT-F" (trade names, manufactured by Nippon Fine Chemicals Co., Ltd.), "Aruflow S-10", "Aruflow E-10", "Aruflow P-10" (trade names, manufactured by NOF Corporation), "Armoslip CP Powder", "Armoslip HT Powder", "Armoslip E" (trade names, manufactured by Lion Specialty Chemicals Co., Ltd.), "Fatty Acid Amide S", "Fatty Acid Amide O-N", "Fatty Acid Amide E" (trade names, manufactured by Kao Corporation), and the like.

[0158] When the fatty acid amide is contained as the internal mold release agent, the content of the fatty acid amide is preferably in the range of 30 to 100 mass %, more preferably in the range of 50 to 100 mass %, and even more preferably in the range of 70 to 100 mass %, based on the total amount of the internal mold release agent, from the viewpoints of the water resistance and water whitening resistance of the coating film to be formed, and the releasability between the coating film to be formed and the mold.

[0159] Examples of the fatty acid tertiary amides include 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, N,N-diethylstearic acid amide, and N,N-dimethyloleic acid amide.

[0160] The internal release agent containing a fatty acid tertiary amide may be a commercially available product, such as "INT-120IMC" (product name, manufactured by AXEL PLASTICS).

[0161] When a fatty acid tertiary amide is contained as the internal release agent, the content of the fatty acid tertiary amide is preferably in the range of 20 to 100 mass %, more preferably in the range of 35 to 100 mass %, and even more preferably in the range of 50 to 100 mass %, based on the total amount of the internal release agent, from the viewpoints of the water resistance and water whitening resistance of the coating film to be formed, and the releasability between the coating film to be formed and the mold.

[0162] Examples of the fatty acid tertiary dimethylamides include N,N-dimethyllauric acid amide, N,N-dimethylmyristic acid amide, N,N-dimethylpalmitic acid amide, N,N-dimethylstearic acid amide, and N,N-dimethyloleic acid amide.

[0163] The internal release agent containing a fatty acid tertiary dimethylamide may be a commercially available product, such as "INT-120IMC" (product name, manufactured by AXEL PLASTICS).

[0164] When a fatty acid tertiary dimethylamide is contained as the internal mold release agent, the content of the fatty acid tertiary dimethylamide is preferably in the range of 20 to 100 mass %, more preferably in the range of 35 to 100 mass %, and even more preferably in the range of 50 to 100 mass %, based on the total amount of the internal mold release agent, from the viewpoints of the water resistance and water whitening resistance of the coating film to be formed, and the releasability between the coating film to be formed and the mold.

[0165] When the main component of the coating composition of the present invention contains the above-mentioned internal release agent, the content of the internal release agent is preferably in the range of 0.3 to 5.0 mass %, more preferably in the range of 0.4 to 4.0 mass %, and even more preferably in the range of 0.5 to 3.0 mass %, based on the total amount of the main component of the coating composition, from the viewpoints of the weather resistance, water resistance, and water-whitening resistance of the coating film to be formed, as well as the releasability between the coating film to be formed and the mold.

[0166] The in-mold coating method can be any conventional method of molding and coating in a mold without any particular limitation. Specifically, for example, the methods described in JP-A 2000-141407 and JP-A 2008-525212 can be used.

[0167] The resin molding mold used when molding the resin material and the in-mold coating mold used when coating the in-mold with the in-mold coating paint composition may be the same or different.

[0168] 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.

[0169] 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.

[0170] From the viewpoint of 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, such as a fluorine-based, silicone-based, surfactant-based, or wax-based external mold release agent.

[0171] 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 temperature of the mold 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.

[0172] The molding time of 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 damage the molded shape when the in-mold coating paint composition is injected, and usually about 20 seconds to 60 minutes is preferred.

[0173] The amount of the in-mold coating composition to be injected is an amount sufficient to obtain a desired film thickness, and is preferably an amount sufficient to obtain a cured film thickness of 15 to 2000 μm.

[0174] 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.

[0175] 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.

[0176] When the uncured in-mold coating film is heated and cured, it is preferable to apply pressure.

[0177] When the pressure is applied, it is preferable that the pressure be within the range of 2 to 14 MPa from the viewpoint of the water resistance and popping resistance of the coating film to be formed.

[0178] The present invention will be explained in more detail below 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.

[0179] Preparation of Hydroxyl-Containing Acrylic Resin Composition (A) 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 mixture was then aged at 150°C for 1 hour and then cooled to obtain a hydroxyl-containing acrylic resin composition (A-1) with a solids concentration of 100% by mass. The hydroxyl-containing acrylic resin (a1) in the resulting hydroxyl-containing acrylic resin composition (A-1) had a hydroxyl value of 172 mgKOH / g, a number average molecular weight of 1,900, and a glass transition temperature of 40°C.

[0180] Production Examples 2 to 11 Solutions of hydroxyl-containing acrylic resin compositions (A-2) to (A-11) were obtained in the same manner as in Production Example 1, except that the blending compositions in Production Example 1 were as shown in Table 1. Table 1 also shows the acid value, hydroxyl value, number average molecular weight, and glass transition temperature of the hydroxyl-containing acrylic resin in each hydroxyl-containing acrylic resin composition.

[0181]

[0182]

[0183] Preparation of Hydroxyl-Containing Acrylic Resin (R) Preparation Example 12: A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube, and dropping device was charged with 32 parts of propylene glycol monomethyl ether acetate. The reaction vessel was stirred at 150°C while nitrogen gas was blown into it, 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 mixture was then aged at 150°C for 1 hour and then cooled to obtain a hydroxyl-containing acrylic resin (R-1) solution with a solids concentration of 65% by mass. The resulting hydroxyl-containing acrylic resin (R-1) had a hydroxyl value of 172 mgKOH / g, a number average molecular weight of 1,900, and a glass transition temperature of 40°C.

[0184] Production of Pigment Paste (P) Production Example 13: 20 parts of "PLACCEL 303" (trade name, manufactured by Daicel Corporation, hydroxyl group-containing polycaprolactone resin, number average molecular weight 310, solids concentration 100%), 8.7 parts of butyl acetate, 4.3 parts of "RAVEN 5000 ULTRA III POWDER" (trade name, manufactured by BIRLA CARBON, carbon black pigment, solids concentration 100%), 0.4 parts of "SOLSPERSE 5000S" (trade name, manufactured by LUBRISOL, phthalocyanine pigment derivative, solids concentration 100%), and 2.4 parts of "DISPERBYK-2013" (trade name, manufactured by BYK-Chemie, dispersant, solids concentration 100%) were placed in a container equipped with a stirrer and mixed uniformly. The resulting mixed solution was then placed in a wide-mouthed glass bottle, and glass beads with a diameter of about 1.3 mm were added as a dispersion medium, followed by sealing. The mixture was dispersed for 4 hours using a paint shaker to obtain a pigment paste (P-1).

[0185] Preparation of In-Mold Coating Composition Example 1 Into a vessel equipped with a stirrer, 100 parts of the hydroxyl group-containing acrylic resin composition (A-1) obtained in Preparation Example 1, 1.3 parts of "Moldwiz INT-120IMC" (trade name, manufactured by Axel Plastics, fatty acid tertiary dimethylamide-containing mixture, solids concentration 100%), 2.1 parts of "TINUVIN 400" (trade name, manufactured by BASF, triazine-based ultraviolet absorber, solids concentration 85%), 4.2 parts of "TINUVIN 292" (trade name, manufactured by BASF, hindered amine compound light stabilizer, solids concentration 100%), and 1.3 parts of "Neostan U-830" (trade name, manufactured by Nitto Kasei Co., Ltd., dioctyltin diversatate, solids concentration 100%) were added to a base resin containing "Desmodur" The mixture was uniformly mixed with 115.4 parts of a curing agent containing 115.4 parts of "N3900" (trade name, manufactured by Sumika Covestro Urethane Co., Ltd., iminooxadiazinedione of hexamethylene diisocyanate, solid content 100%) to obtain In-mold Coating Composition No. 1 with a solid content of 99.9%. The mixture was heated at a temperature of 65°C and a shear rate of 100 sec. －１ The viscosity of the base material is 3000 mPa·s, the temperature is 65°C, and the shear rate is 100 sec －１ The viscosity of the curing agent was 100 mPa·s.

[0186] Examples 2 to 8, 10 to 19 and Comparative Examples 1 and 2 In-mold coating coating compositions Nos. 2 to 8 and Nos. 10 to 21 were obtained in the same manner as in Example 1, except that the blending compositions in Example 1 were as shown in Table 2 below.

[0187] Example 9 Into a vessel equipped with a stirrer, 60 parts of the hydroxyl-containing acrylic resin composition (A-1) obtained in Production Example 1, 20 parts of "PLACCEL 303" (trade name, manufactured by Daicel Corporation, hydroxyl-containing polycaprolactone resin, number average molecular weight 310, solid content 100%), 1.3 parts of "Moldwiz INT-120IMC" (trade name, manufactured by Axel Plastics, fatty acid tertiary dimethylamide-containing mixture, solid content 100%), 2.0 parts of "TINUVIN 400" (trade name, manufactured by BASF, triazine-based ultraviolet absorber, solid content 85%), 4.0 parts of "TINUVIN 292" (trade name, manufactured by BASF, hindered amine compound light stabilizer, solid content 100%), and "Neostan The base material contained 1.2 parts of "U-830" (trade name, manufactured by Nitto Kasei Co., Ltd., dioctyl tin diversatate, solids concentration 100%), 93.5 parts of "Desmodur N3900" (trade name, manufactured by Sumika Covestro Urethane Co., Ltd., iminooxadiazinedione of hexamethylene diisocyanate, solids concentration 100%), 47.0 parts of "Desmodur NZ200" (trade name, manufactured by Sumika Covestro Urethane Co., Ltd., a mixture of isocyanurate of hexamethylene diisocyanate and isocyanurate of isophorone diisocyanate, solids concentration 100%), and "Carbodilite A curing agent containing 3.6 parts of "V-05" (trade name, manufactured by Nisshinbo Chemical Inc., a carbodiimide group-containing compound having an aromatic ring structure and two isocyanate groups, a carbodiimide equivalent per solid content of 262, a number average molecular weight of 800, and a solid content concentration of 100%) and 35.8 parts of the pigment dispersion (P-1) obtained in Production Example 13 were uniformly mixed to obtain an in-mold coating paint composition No. 9 with a solid content concentration of 99.2%. The mixture was heated at a temperature of 65°C and a shear rate of 100 sec. －１ The viscosity of the base material is 1200 mPa·s, the temperature is 65°C, and the shear rate is 100 sec －１ The viscosity of the curing agent was 140 mPa·s, the temperature was 65°C, and the shear rate was 100 sec －１ The viscosity of the pigment dispersion (P-1) was 1200 mPa·s.

[0188] Temperature: 65°C, shear rate: 100 sec －１ Viscosity at temperature 65°C, shear rate 100 sec －１The viscosity at 200°C was measured by the following method.

[0189] Shearing rate 100sec －１ The temperature was increased from 20°C to 80°C at a rate of 5°C / min, and the shear rate was 100 sec. －１ The viscosity at a temperature of 65°C was measured using a cone and plate viscometer "MCR-302e" (trade name, manufactured by Anton Paar, diameter 25 mm, cone and plate tilted at 2°).

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[0191]

[0192]

[0193]

[0194] The components listed in the table are as follows: (*1) "URIC F-97": trade name, manufactured by Ito Oil Mills, castor oil modified polyol, solids concentration 100%, (*2) "Desmodur N3400": trade name, manufactured by Sumika Covestro Urethane Co., Ltd., mixture of uretdione and isocyanurate of hexamethylene diisocyanate, solids concentration 100%, (*3) "Desmodur N3600": trade name, manufactured by Sumika Covestro Urethane Co., Ltd., isocyanurate of hexamethylene diisocyanate, solids concentration 100%.

[0195] Preparation of In-Mold Coated Molded Product Example 20 (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 in-mold coating paint 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, thereby producing an in-mold coated molding (M1-1) in which a coating film with a cured film thickness of 300 μm was coated on a flat "DIALAC TW20" molding.

[0196] Examples 21 to 38, Comparative Examples 3 to 4 In-mold coated moldings (M1-2) to (M1-21) were prepared in the same manner as in Example 20, except that the types of in-mold coating paint compositions in Example 20 were as shown in Table 3 below.

[0197] Evaluation of in-mold coated moldings Each of the obtained in-mold coated moldings was evaluated for water-resistant adhesion, water-whitening resistance, hardness, weather resistance, popping resistance, and mold releasability. The evaluation results are shown in Table 3.

[0198] (Water-Resistant Adhesion) Each of the in-mold coated moldings obtained in Examples 20 to 38 and Comparative Examples 3 and 4 was immersed in 40°C warm water for 240 hours, then removed and dried at 20°C for 24 hours. Next, the coating film of each in-mold coated molding after the water resistance test was cut into a grid pattern with a cutter so as to reach the substrate, creating 100 2mm x 2mm cross-hatched patterns. Next, adhesive cellophane tape was attached to the cut surface of each in-mold coated molding, and the adhesive cellophane tape was rapidly peeled off at a temperature of 23±2°C and a humidity of 50±5% relative humidity. The remaining state of the cross-hatched coating film after peeling was examined, and the adhesion after the water resistance test was evaluated based on the following criteria. A, B, and C were considered acceptable. A: 100 cross-hatched coating films remain, and there are no small chips or lifting of the coating film at the edges of the cutter notches; B: 100 cross-hatched coating films remain, and there are small chips or lifting of the coating film at the edges of the cutter notches; C: 90 to 99 cross-hatched coating films remain; D: 80 to 89 cross-hatched coating films remain; E: The number of remaining cross-hatched coating films is 79 or less.

[0199] (Water Whitening Resistance) Each of the in-mold coated moldings obtained in Examples 20 to 38 and Comparative Examples 3 and 4 was irradiated with light at angles of 25°, 45°, and 75° relative to the axis perpendicular to the coating film surface using a multi-angle spectrophotometer "CM-512m3" (trade name, manufactured by Konica Minolta, Inc.), and the L ＊ , a ＊ , b ＊ The test panels were then immersed in warm water at 40°C for 240 hours. After immersion in warm water, the test panels were irradiated with light at angles of 25°, 45°, and 75° relative to the axis perpendicular to the coating surface using the multi-angle spectrophotometer "CM-512m3" (trade name, manufactured by Konica Minolta Inc.). The L ＊ , a ＊ , b ＊ Then, the color of the L before and after immersion in hot water was measured. ＊ , a ＊ , b ＊ From the color measurement values, ΔE at 25°, 45° and 75° according to JIS K 5600-4-6 (1999) ＊ (25°), ΔE ＊(45°) and ΔE ＊ (75°) is calculated, and ΔE ＊ (25°), ΔE ＊ (45°) and ΔE ＊ (75°) ＊ The evaluation was carried out based on the following criteria. A, B and C are acceptable. A: ΔE ＊ B: ΔE is less than 1.0 ＊ C: ΔE is 1.0 or more and less than 1.5 ＊ D: ΔE is 1.5 or more and less than 2.0 ＊ is 2.0 or more and less than 3.0, E: ΔE ＊ is 3.0 or more.

[0200] (Hardness) The Martens hardness (N / mm2) of each of the in-mold coated moldings obtained in Examples 20 to 38 and Comparative Examples 3 and 4 was measured using a "Fisherscope (registered trademark) HM2000S" (product name, manufactured by Fisher Instruments) and evaluated based on the following criteria. The measurement conditions were as follows: indenter: square pyramidal Vickers indenter (material: diamond, facing angle: 136°), maximum test load: 20 mN, indentation speed: 20 mN / 25 seconds, temperature: 21±2°C, humidity: 50±5% relative humidity. A, B, and C are acceptable. A: Martens hardness is 125 N / mm2 or more; B: Martens hardness is 100 N / mm2 or more and less than 125 N / mm2; C: Martens hardness is 75 N / mm2 or more and less than 100 N / mm2; D: Martens hardness is 50 N / mm2 or more and less than 75 N / mm2; E: Martens hardness is less than 50 N / mm2.

[0201] (Weather resistance) For each of the in-mold coated moldings obtained in Examples 20 to 38 and Comparative Examples 3 and 4, a multi-angle spectrophotometer "CM-512m3" (trade name, manufactured by Konica Minolta, Inc.) was used to irradiate light from angles of 25°, 45°, and 75° relative to the axis perpendicular to the coating surface, and the L ＊ , a ＊ , b ＊The color was measured. Next, in accordance with JIS K 5600-7-7, an accelerated weathering test was carried out using a "Super Xenon Weather Meter" (a weathering tester manufactured by Suga Test Instruments Co., Ltd.) under the conditions of a test piece wetting cycle of 18 minutes / 2 hours, a black panel temperature of 61 to 65°C, and a lamp irradiation time of 1,200 hours. Next, for each of the in-mold coated moldings after the accelerated weathering test, light was irradiated from angles of 25°, 45°, and 75° relative to the axis perpendicular to the coating film surface using the above-mentioned multi-angle spectrophotometer "CM-512m3" (trade name, manufactured by Konica Minolta Inc.), and the L ＊ , a ＊ , b ＊ Then, the L before and after the accelerated weather resistance test was measured. ＊ , a ＊ , b ＊ From the color measurement values, ΔE at 25°, 45° and 75° according to JIS K 5600-4-6 (1999) ＊ (25°), ΔE ＊ (45°) and ΔE ＊ (75°) is calculated, and ΔE ＊ (25°), ΔE ＊ (45°) and ΔE ＊ (75°) ＊ The evaluation was based on the following criteria: ＊ The smaller the ΔE, the less discoloration of the test panel and the better the weather resistance. A, B and C are acceptable. A: ΔE ＊ B: ΔE is less than 1.0 ＊ C: ΔE is 1.0 or more and less than 1.5 ＊ D: ΔE is 1.5 or more and less than 2.0 ＊ is 2.0 or more and less than 3.0, E: ΔE ＊ is 3.0 or more.

[0202] (Pockmark Resistance) The in-mold coated moldings obtained in Nos. 20 to 38 and Comparative Examples 3 and 4 were observed with the naked eye, the number of poppies that had appeared on the coating surface was counted, and poppy resistance was evaluated according to the following criteria. A, B, and C are acceptable. A: There are no poppies of 1 mm or more on the coating surface, and there are 3 or fewer poppies less than 1 mm. B: There are no poppies of 1 mm or more on the coating surface, and there are 4 to 6 poppies less than 1 mm. C: There are no poppies of 1 mm or more on the coating surface, and there are 7 or more poppies less than 1 mm. D: There are 1 to 3 poppies of 1 mm or more on the coating surface. E: There are 4 or more poppies of 1 mm or more on the coating surface.

[0203] (Mold release property) In the preparation of the in-mold coated molding (M1), 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 release test was carried out to determine whether the in-mold coated molding could be released from the coating film coated mold. If the mold release was not successful, 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 release test was carried out in the same manner. This was repeated for all four corners until the mold release, up to a total of four times. In addition, for in-mold coated moldings from which the coating film had peeled, 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 release property was evaluated according to the following criteria. A, B, and C were 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; C: The in-mold coated molded product was released from the mold in the 1st to 4th mold release test, and the coating film peeling score was 1 point; D: The in-mold coated molded product was released from the mold in the 1st to 4th mold release test, and the coating film peeling score was 2 or more points; E: 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.

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[0206]

Claims

1. A coating composition comprising (A) a base material containing a hydroxyl-containing acrylic resin composition containing (a1) a hydroxyl-containing acrylic resin and (a2) a polyhydric alcohol, and (B) a curing agent containing a polyisocyanate compound, wherein the hydroxyl-containing acrylic resin (a1) is synthesized by a solution polymerization method, and the solution used in the solution polymerization method contains the polyhydric alcohol (a2).

2. The coating composition according to claim 1, wherein the melting point of the polyhydric alcohol (a2) is within the range of 10 to 150°C.

3. The coating composition according to claim 1, wherein the polyhydric alcohol (a2) has a number average molecular weight of 1,000 or less.

4. A coating composition as described in claim 1, having a solids concentration of 90 mass% or more.

5. 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 a paint composition according to any one of claims 1 to 4.

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