COATING COMPOSITION HAVING HIGH SOLID CONTENT AND METHOD FOR FORMING MULTILAYER COATING FILM

Abstract

A high-solid-content coating composition includes: (A) a hydroxy group-containing acrylic resin having a glass transition temperature (Tg) in a range of 20 C. to 70 C. and a weight average molecular weight in a range of 3,000 to 10,000; (B) a hydroxy group-containing polyester resin being a reaction product of a polyfunctional compound (b-1) having a carboxy group and a hydroxy group in total of three or more in one molecule, a monoepoxide compound (b-2) having a hydrocarbon group having 4 or more carbon atoms, and a caprolactone compound (b-3); and (C) a polyisocyanate compound, in which a solid content at the time of coating is 50 mass % or more.

Claims

1. A high-solid-content coating composition, comprising: (A) a hydroxy group-containing acrylic resin having a glass transition temperature (Tg) in a range of 20 C. to 70 C. and a weight average molecular weight in a range of 3,000 to 10,000; (B) a hydroxy group-containing polyester resin being a reaction product of a polyfunctional compound (b-1) having a carboxy group and a hydroxy group in total of three or more in one molecule, a monoepoxide compound (b-2) having a hydrocarbon group having 4 or more carbon atoms, and a caprolactone compound (b-3); and (C) a polyisocyanate compound, wherein a solid content at the time of coating is 50 mass % or more.

2. The high-solid-content coating composition according to claim 1, wherein the hydroxy group-containing acrylic resin (A) comprises a hydroxy group-containing acrylic resin (A) having an alkoxysilyl group.

3. The high-solid-content coating composition according to claim 1, wherein an acid value of the hydroxy group-containing polyester resin (B) is 30 mgKOH/g or less.

4. The high-solid-content coating composition according to claim 1, wherein the polyfunctional compound (b-1) having a carboxy group and a hydroxy group in total of three or more is a compound having one carboxy group and two hydroxy groups.

5. The high-solid-content coating composition according to claim 1, wherein the hydroxy group-containing polyester resin (B) further comprises a polybasic acid compound (b-4) as a reaction component.

6. A method for forming a multilayer coating film, the method comprising: a step (1): coating an object to be coated with an intermediate coating composition to form an intermediate coating film; a step (2): coating the intermediate coating film formed in the step (1) with a basecoat coating composition to form a basecoat coating film; a step (3): coating the basecoat coating film formed in the step (2) with the highsolid-content coating composition according to claim 1 to form a clearcoat coating film; and a step (4): heating and curing the intermediate coating film, the basecoat coating film, and the clearcoat coating film formed in the steps (5 1) to (3) at once.

Description

EXAMPLES

[0207] Hereinafter, the present invention will be described more specifically with reference to Production Examples, Examples, and Comparative Examples. However, the present invention is not limited thereto. In each example, parts and % are based on mass unless otherwise specified. A film thickness of a coating film is based on a cured coating film.

[0208] [1] Preparation of Object to be Coated

[0209] A degreased and zinc phosphate-treated steel sheet (JISG3141, size: 400 mm300 mm0.8 mm) was electrodeposition coated with a cationic electrodeposition coating ELECRON GT-10 (trade name, manufactured by Kansai Paint Co., Ltd., a material in which a blocked polyisocyanate compound was used as a curing agent for an epoxy resin polyamine-based cationic resin) so as to have a film thickness of 20 m based on a cured coating film, and was heated at 170 C. for 20 minutes for crosslinking and curing, so as to form an electrodeposition coating film thereby obtaining an object to be coated.

[0210] [2] Preparation of Coating

[0211] <Production of Hydroxy Group-Containing Acrylic Resin (A)>

Production Example 1

[0212] A reaction vessel including a thermometer, a thermostat, a stirrer, a reflux condenser, a nitrogen inlet tube, and a dropping device was charged with 27 parts of Swasol 1000 (trade name, manufactured by Cosmo Oil Co., Ltd, aromatic-based organic solvent) and 5 parts of propylene glycol monomethyl ether acetate. The charged solution was stirred at 150 C. while nitrogen gas was blown into the reaction vessel, and a monomer mixture containing 20 parts of styrene, 32.5 parts of 2-hydroxypropyl acrylate, 46.2 parts of isobutyl methacrylate, 1.3 parts of acrylic acid, and 3.2 parts of di-tertiary amyl peroxide (polymerization initiator) was added dropwise thereto at a uniform rate over 4 hours. Thereafter, the mixture was aged at 150 C. for 1 hour, cooled, and further diluted by adding 21 parts of isobutyl acetate to obtain a solution of a hydroxy group-containing acrylic resin (A-1) having a solid content concentration of 65%. The obtained hydroxy group-containing acrylic resin (A-1) had an acid value of 10.1 mgKOH/g, a hydroxy value of 140 mgKOH/g, a weight average molecular weight of 8,000, and a glass transition temperature of 39 C.

Production Examples 2 to 4

[0213] In Production Example 1, solutions of hydroxy group-containing acrylic resins (A-2) to (A-4) having a solid content concentration of 65% were obtained in the same manner as in Production Example 1, except that blending compositions were as shown in Table 1. Table 1 also shows an acid value, a hydroxy value, a weight average molecular weight, and a glass transition temperature of each hydroxy group-containing acrylic resin.

TABLE-US-00001 TABLE 1 Production Example 1 2 3 4 Name of hydroxy group-containing acrylic resin (A) A-1 A-2 A-3 A-4 Monomer Acid group-containing Acrylic acid 1.3 1.3 1.3 1.3 mixture polymerizable unsaturated monomer Hydroxy group- 2-hydroxypropyl acrylate 32.5 32.5 32.5 32.5 containing polymerizable unsaturated monomer Other polymerizable Styrene 20 20 20 30 unsaturated monomers Isobutyl methacrylate 46.2 46.2 34.2 N-butyl acrylate 12 Methyl methacrylate 36.2 Polymerization initiator Di-tertiary amyl peroxide 3.2 5.5 3.2 3.2 Acid value (mgKOH/g) 10.1 10.1 10.1 10.1 Hydroxy value (mgKOH/g) 140 140 140 140 Weight average molecular weight 8,000 4,500 8,000 8,000 Glass transition temperature ( C.) 39 39 22 58

[0214] <Production of Hydroxy Group-Containing Acrylic Resin (A) Having Alkoxysilyl Group>

Production Example 5

[0215] A reaction vessel including a thermometer, a thermostat, a stirrer, a reflux condenser, a nitrogen inlet tube, and a dropping device was charged with 30 parts of Swasol 1000 (trade name, manufactured by Cosmo Oil Co., Ltd, aromatic-based organic solvent) and 10 parts of n-butanol. The charged solution was stirred at 125 C. while nitrogen gas was blown into the reaction vessel, and a monomer mixture containing 15 parts of -methacryloxypropyltrimethoxysilane, 32.5 parts of 2-hydroxyethyl methacrylate, 10 parts of styrene, 10 parts of 2-ethylhexyl acrylate, 32.5 parts of isobutyl methacrylate, and 7.0 parts of 2,2-azo bis(2-methylbutylonitrile) (polymerization initiator) was added dropwise thereto at a uniform rate over 4 hours. Thereafter, the mixture was aged at 125 C. for 30 minutes, and then a solution containing 0.5 parts of 2,2-azo bis(2-methylbutylonitrile) and 5.0 parts of Swasol 1000 was added dropwise at a uniform rate over 1 hour. Thereafter, the mixture was aged at 125 C. for 1 hour, cooled, and further diluted by adding 6 parts of isobutyl acetate to obtain a solution of a hydroxy group-containing acrylic resin (A-1) containing an alkoxysilyl group and having a solid content concentration of 65%. The obtained hydroxy group-containing acrylic resin (A-1) containing an alkoxysilyl group had an alkoxysilyl group content of 60 mmol/g, a hydroxy value of 140 mgKOH/g, a weight average molecular weight of 7,000, and a glass transition temperature of 32 C.

[0216] <Production of Hydroxy Group-Containing Acrylic Resin (D)>

Production Example 6

[0217] A reaction vessel including a thermometer, a thermostat, a stirrer, a reflux condenser, a nitrogen inlet tube, and a dropping device was charged with 27 parts of Swasol 1000 (trade name, manufactured by Cosmo Oil Co., Ltd, aromatic-based organic solvent) and 5 parts of propylene glycol monomethyl ether acetate. The charged solution was stirred at 150 C. while nitrogen gas was blown into the reaction vessel, and a monomer mixture containing 20 parts of styrene, 32.5 parts of 2-hydroxypropyl acrylate, 46.2 parts of isobutyl methacrylate, 1.3 parts of acrylic acid, and 2.0 parts of di-tertiary amyl peroxide (polymerization initiator) was added dropwise thereto at a uniform rate over 4 hours. Thereafter, the mixture was aged at 150 C. for 1 hour, cooled, and further diluted by adding 21 parts of isobutyl acetate to obtain a solution of a hydroxy group-containing acrylic resin (D-1) having a solid content concentration of 65%. The obtained hydroxy group-containing acrylic resin (D-1) had an acid value of 10.1 mgKOH/g, a hydroxy value of 140 mgKOH/g, a weight average molecular weight of 11,000, and a glass transition temperature of 39 C.

Production Examples 7 to 9

[0218] In Production Example 6, solutions of hydroxy group-containing acrylic resins (D-2) to (D-4) having a solid content concentration of 65% were obtained in the same manner as in Production Example 6, except that blending compositions were as shown in Table 2. Table 2 also shows an acid value, a hydroxy value, a weight average molecular weight, and a glass transition temperature of each hydroxy group-containing acrylic resin.

TABLE-US-00002 TABLE 2 Production Example 6 7 8 9 Name of hydroxy group-containing acrylic resin (D) D-1 D-2 D-3 D-4 Monomer Acid group-containing Acrylic acid 1.3 1.3 1.3 1.3 mixture polymerizable unsaturated monomer Hydroxy group- 2-hydroxypropyl acrylate 32.5 32.5 32.5 12.5 containing polymerizable 2-hydroxyethyl methacrylate unsaturated monomer 20 Other polymerizable Styrene 20 20 20 30 unsaturated monomers Isobutyl methacrylate 46.2 46.2 30 N-butyl acrylate 16.2 Methyl methacrylate 36.2 Polymerization initiator Di-tertiary amyl peroxide 2 8 3.2 3.2 Acid value (mgKOH/g) 10.1 10.1 10.1 10.1 Hydroxy value (mgKOH/g) 140 140 140 140 Weight average molecular weight 11,000 2,500 8,000 8,000 Glass transition temperature ( C.) 39 39 17 75

Production Example 10

[0219] A reaction vessel including a thermometer, a thermostat, a stirrer, a reflux condenser, a nitrogen inlet tube, and a dropping device was charged with 27 parts of Swasol 1000 (trade name, manufactured by Cosmo Oil Co., Ltd, aromatic-based organic solvent) and 5 parts of propylene glycol monomethyl ether acetate. The charged solution was stirred at 150 C. while nitrogen gas was blown into the reaction vessel, and a monomer mixture containing 11.5 parts of 2-ethylhexyl methacrylate, 40 parts of 2-hydroxyethyl methacrylate, 38 parts of isobutyl acrylate, 10.5 parts of acrylic acid, and 6.5 parts of di-tertiary amyl peroxide (polymerization initiator) was added dropwise thereto at a uniform rate over 4 hours. Thereafter, the mixture was aged at 150 C. for 1 hour, cooled, and further diluted by adding 21 parts of isobutyl acetate to obtain a solution of a hydroxy group-containing acrylic resin (D1-1) having a solid content concentration of 65%. The obtained hydroxy group-containing acrylic resin (D1-1) had an acid value of 81.8 mgKOH/g, a hydroxy value of 173 mgKOH/g, a weight average molecular weight of 3,500, and a glass transition temperature of 17 C.

[0220] <Production of Hydroxy Group-Containing Polyester Resin (B)>

Production Example 11

[0221] A reaction vessel including a stirrer, a reflux condenser, and a thermometer was charged with 148 parts of dimethylol butanoic acid, 735 parts of Cardura E10P (trade name, manufactured by Momentive Specialty Chemicals Inc., neodecanoic acid monoglycidyl ester), and 308 parts of hexahydrophthalic anhydride, and the mixture was reacted at 190 C. for 3 hours. Thereafter, 342 parts of c-caprolactone were added thereto, and the mixture was reacted at 190 C. for 3 hours, and then diluted with butyl acetate to obtain a solution of a hydroxy group-containing polyester resin (B-1) having a solid content concentration of 80%. The obtained hydroxy group-containing polyester resin (B-1) had an acid value of 4 mgKOH/g, a hydroxy value of 120 mgKOH/g, and a number average molecular weight of 2,100.

Production 12 to 17

[0222] In Production Example 11, solutions of hydroxy group-containing polyester resins (B-2) to (B-7) having a solid content concentration of 80% were obtained in the same manner as in Production Example 11, except that blending compositions were as shown in Table 3. Table 3 also shows an acid value, a hydroxy value, and a number average molecular weight of each hydroxy group-containing polyester resin.

TABLE-US-00003 TABLE 3 Production Example 11 12 13 14 15 16 17 Name of hydroxy group-containing polyester resin (B) B-1 B-2 B-3 B-4 B-5 B-6 B-7 Polyfunctional compound (b-1) Dimethylol butanoic acid 148 134 134 148 having carboxy group and hydroxy Malic acid 134 group in total of three or more in Citric acid 192 one molecule Tartaric acid 150 Monoepoxide compound (b-2) Cardura E10P 735 735 613 245 735 980 980 having hydrocarbon group having 4 or more carbon atoms Polybasic acid compound (b-4) Hexahydrophthalic 308 308 308 154 154 308 anhydride Caprolactone compound (b-3) -caprolactone 342 456 262 342 342 456 456 Acid value (mgKOH/g) 4 12 21 2 4 3 4 Hydroxy value (mgKOH/g) 120 120 111 232 128 98 93 Number average molecular weight 1,529 1,633 1,317 733 1,361 1,779 1,890

[0223] <Production of Hydroxy Group-Containing Polyester Resin (E) Other Than Hydroxy Group-Containing Polyester Resin (B)>

Production Example 18

[0224] A reaction vessel including a stirrer, a reflux condenser, and a thermometer was charged with 90 parts of lactic acid, 490 parts of Cardura E10P (trade name, manufactured by Momentive Specialty Chemicals Inc., neodecanoic acid monoglycidyl ester), and 154 parts of hexahydrophthalic anhydride, and the mixture was reacted at 190 C. for 3 hours. Thereafter, 228 parts of -caprolactone were added thereto, and the mixture was reacted at 190 C. for 3 hours, and then diluted with butyl acetate to obtain a solution of a hydroxy group-containing polyester resin (E-1) having a solid content concentration of 80%. The obtained hydroxy group-containing polyester resin (E-1) had an acid value of 1 mgKOH/g, a hydroxy value of 176 mgKOH/g, and a number average molecular weight of 961.

Production Example 19

[0225] A reaction vessel including a stirrer, a reflux condenser, and a thermometer was charged with 148 parts of dimethylol butanoic acid, 735 parts of Cardura E10P (trade name, manufactured by Momentive Specialty Chemicals Inc., neodecanoic acid monoglycidyl ester), and 308 parts of hexahydrophthalic anhydride, and the mixture was reacted at 190 C. for 6 hours, and then diluted with butyl acetate to obtain a solution of a hydroxy group-containing polyester resin (E-2) having a solid content concentration of 80%. The obtained hydroxy group-containing polyester resin (E-2) had an acid value of 1 mgKOH/g, a hydroxy value of 142 mgKOH/g, and a number average molecular weight of 1,190.

Production Example 20

[0226] A reaction vessel including a stirrer, a reflux condenser, a water separator, and a thermometer was charged with 100.1 parts of hexahydrophthalic anhydride and 118 parts of 1,6-hexanediol, and the mixture was reacted at 230 C. for 6 hours, and then diluted with butyl acetate to obtain a solution of a hydroxy group-containing polyester resin (E-3) having a solid content concentration of 80%. The obtained hydroxy group-containing polyester resin (E-3) had an acid value of 2 mgKOH/g, a hydroxy value of 192 mgKOH/g, and a number average molecular weight of 578. <Production of High-Solid-Content Coating Composition>

Example 1

[0227] A main agent obtained by uniformly mixing 76.9 parts (solid content: 50 parts) of the solution of the hydroxy group-containing acrylic resin (A-1) obtained in Production Example 1, 10 parts (solid content: 8 parts) of the solution of the hydroxy group-containing polyester resin (B-1) obtained in Production Example 11, 0.5 parts (solid content: 0.3 parts) of SETALUX 61767 VX-60 (trade name, manufactured by Allnex, viscosity modifier, solid content: 60%), and 0.4 parts (solid content: 0.2 parts) of BYK-300 (trade name, manufactured by BYK-Chemie, surface conditioner, active component: 52%), and 42 parts of Sumidur N3300 (trade name, manufactured by Sumika Covestro Urethane Co., Ltd., isocyanurate of hexamethylene diisocyanate, solid content: 100%) as a curing agent were uniformly mixed immediately before coating, and butyl acetate was added thereto to adjust a solid content at the time of coating to 58%, thereby obtaining a high-solid-content coating composition No. 1.

Examples 2 to 18 and Comparative Examples 1 to 9

[0228] High-solid-content coating compositions No. 2 to No. 27 were obtained in the same manner as the high-solid-content coating composition No. 1, except that blending compositions and solid contents at the time of coating were as shown in Tables 4 to 8 below. The blending compositions shown in Tables 4 to 8 are based on a solid content mass of each component.

[0229] <Preparation of Test Plate>

[0230] The object to be coated prepared in the above [1] was electrostatically coated with WP-523H (trade name, manufactured by Kansai Paint Co., Ltd., acrylic/melamine resin-based aqueous intermediate coating composition) using a rotary atomization type electrostatic coating machine so as to have a cured film thickness of 20 m, and was allowed to stand for 5 minutes to form an uncured intermediate coating film.

[0231] Next, the uncured intermediate coating film was electrostatically coated with WBC-713T No. 1F7 (trade name, manufactured by Kansai Paint Co., Ltd., acrylic/melamine resin-based aqueous basecoat coating, silver coating color) using a rotary atomization type electrostatic coating machine so as to have a dry film thickness of 12 m, was allowed to stand for 3 minutes, and then preheated at 80 C. for 5 minutes to form an uncured basecoat coating film.

[0232] Next, the uncured basecoat coating film was electrostatically coated with the high-solid-content coating composition No. 1 using a rotary atomization type electrostatic coating machine so as to have a dry film thickness of 35 m to form a clearcoat coating film, which was allowed to stand for 7 minutes. Next, by heating at 140 C. for 30 minutes, the intermediate coating film, the basecoat coating film, and the clearcoat coating film were heated and cured to prepare a test plate of Example 1.

[0233] In the production of the test plate of the high-solid-content coating composition No. 1, test plates of Examples 2 to 18 and Comparative Examples 1 to 9 were produced in the same manner as in the production of the test plate of the high-solid-content coating composition No. 1, except that the high-solid-content coating composition No. 1 was changed to any one of the high-solid-content coating compositions No. 2 to No. 27.

[0234] Each of the test plates obtained above was evaluated by the following test method. Evaluation results are shown in Tables 4 to 8 together with the coating compositions.

[0235] (Test Method)

[0236] Tukon hardness: The test plate was allowed to stand in a thermostatic chamber at for 4 hours, and then a Tukon hardness was measured with TUKON (manufactured by American Chain&Cable Company, micro hardness tester). The Tukon hardness, which is a Knoop hardness test method, is a numerical value measured by a TUKON micro hardness tester manufactured by American Chain&Cable Company, and the Tukon hardness, also called Knoop hardness number (KHN), is a hardness of a coating film that is determined by pressing a square pyramidal diamond indenter into a test surface of a material with a constant test load and measuring a size of a resulting diamond-shaped indentation. The greater the value is, the greater the hardness is. A value of 10 or more is regarded as acceptable.

[0237] Scratch resistance: The test plate was fixed to a test stand of a car wash test machine (manufactured by Amtec, Carwash Lab Apparatus) under an atmosphere of 20 C., and a car wash brush was rotated at 127 rpm and the test stand was reciprocated 10 times while spraying a test solution obtained by mixing 1.5 g of Sikron SH200 (trade name, silica fine particles having a particle size of 24 m, manufactured by Quarzwerke) with 1 liter of water onto the test plate. Thereafter, water washing and drying were performed, and the 20 gloss before and after the test was measured using a gloss meter (manufactured by Byk-Gardner, device name: Micro Tri Gross), and a gloss retention rate was calculated according to the following equation. The higher the gloss retention rate is, the better the scratch resistance is. A and B are regarded as acceptable.

[0238] Gloss retention rate (%)=(gloss after test/gloss before test)100

[0239] A: Gloss retention rate of 85% or more

[0240] B: Gloss retention rate of 80% or more and less than 85%

[0241] C: Gloss retention rate of less than 80%

[0242] Water resistance: The test plate was immersed in warm water at 40 C. for 240 hours, pulled out, and immediately after wiping off the water on a surface, 100 square grids with a size of 2 mm2 mm were formed on a coated surface according to JIS K 5600-5-6 (1990) on a coating film. An adhesive tape was attached to the surface, and was rapidly peeled off, and then the number of square grid coating films remained on the coated surface was evaluated. A is regarded as acceptable.

[0243] A: Remaining number/total number=100/100, with no edge chipping

[0244] B: Remaining number/total number=100/100, with edge chipping

[0245] C: Remaining number/total number=99 or less

[0246] Finished appearance: A finished appearance was evaluated based on a long wave (LW) value and a short wave (SW) value measured by a Wave Scan (trade name, manufactured by BYK Gardner).

[0247] LW value: An index of smoothness, and the smaller the LW value is, the higher the smoothness of a coated surface is. A value of 6 or less is regarded as acceptable.

[0248] SW value: An index of image clarity, and the smaller the SW value is, the higher the image clarity of a coated surface is. A value of 17 or less is regarded as acceptable.

[0249] Anti-after-tack property: L values (brightness) at an acceptance angle of 15 and an acceptance angle of 110 were measured using a multiangle spectrophotometer MA-68 II (trade name, manufactured by X-Rite), and a flip-flop value was obtained according to the following equation and used as an index of an anti-after-tack property. The higher the flip-flop value is, the better orientation of aluminum is, and the better the anti-after-tack property is. A value of 87 or more is regarded as acceptable.

Flip-flop value=L value at acceptance angle of 15L value at acceptance angle of 110.

TABLE-US-00004 TABLE 4 Example 1 2 3 4 5 6 High-solid-content coating composition NO. 1 2 3 4 5 6 Hydroxy group- Hydroxy group- Acrylic resin (A-1) 50 45 45 43 containing acrylic containing acrylic Acrylic resin (A-2) 45 43 resin (A) resin (A) Acrylic resin (A-3) Acrylic resin (A-4) Hydroxy group- Acrylic resin (A-1) containing acrylic resin having alkoxysilyl group Hydroxy group-containing Acrylic resin (D-1) acrylic resin (D) Acrylic resin (D-2) Acrylic resin (D-3) Acrylic resin (D-4) Acrylic resin (D1-1) 5 5 5 Hydroxy group-containing Polyester resin (B-1) 8 8 8 5 8 5 polyester resin (B) Polyester resin (B-2) Polyester resin (B-3) Polyester resin (B-4) Polyester resin (B-5) Polyester resin (B-6) Polyester resin (B-7) Hydroxy group-containing Polyester resin (E-1) polyester resin (E) Polyester resin (E-2) Polyester resin (E-3) Polyisocyanate compound (C) Sumidur N3300 42 42 42 42 42 42 Melamine resin U-VAN 20SE60 5 5 5 5 Viscosity modifier SETALUX 61767 VX-60 0.3 0.3 0.3 0.3 0.3 0.3 Surface conditioner BYK-300 0.2 0.2 0.2 0.2 0.2 0.2 Solid content at the time of coating (%) 58% 58% 58% 58% 58% 58% Evaluation result Tukon hardness 11 11 11 12 11 11 Scratch resistance A A A A A A Water resistance A A A A A A Finished appearance (LW) 4 4 4 4 3 4 Finished appearance (SW) 14 14 14 14 15 15 Anti-after-tack property 88 91 88 91 87 90 (flip-flop value)

TABLE-US-00005 TABLE 5 Example 7 8 9 10 11 12 High-solid-content coating composition NO. 7 8 9 10 11 12 Hydroxy group-containing Hydroxy group-containing Acrylic resin (A-1) 20 45 45 acrylic resin (A) acrylic resin (A) Acrylic resin (A-2) Acrylic resin (A-3) 45 Acrylic resin (A-4) 45 Hydroxy group-containing Acrylic resin (A-1) 45 25 acrylic resin (A) having alkoxysilyl group Hydroxy group-containing acrylic resin (D) Acrylic resin (D-1) Acrylic resin (D-2) Acrylic resin (D-3) Acrylic resin (D-4) Acrylic resin (D1-1) Hydroxy group-containing polyester resin (B) Polyester resin (B-1) 8 8 8 8 Polyester resin (B-2) 8 Polyester resin (B-3) 8 Polyester resin (B-4) Polyester resin (B-5) Polyester resin (B-6) Polyester resin (B-7) Hydroxy group-containing polyester resin (E) Polyester resin (E-1) Polyester resin (E-2) Polyester resin (E-3) Polyisocyanate compound (C) Sumidur N3300 42 42 42 42 42 42 Melamine resin U-VAN 20SE60 5 5 5 5 5 5 Viscosity modifier SETALUX 61767 VX-60 0.3 0.3 0.3 0.3 0.3 0.3 Surface conditioner BYK-300 0.2 0.2 0.2 0.2 0.2 0.2 Solid content at the time of coating (%) 58% 58% 58% 58% 58% 58% Evaluation result Tukon hardness 10 13 12 11 11 11 Scratch resistance A B A A A A Water resistance A A A A A A Finished appearance (LW) 4 6 5 4 5 5 Finished appearance (SW) 15 17 14 15 15 16 Anti-after-tack property 87 89 88 88 89 91 (flip-flop value)

TABLE-US-00006 TABLE 6 Example 13 14 15 16 17 18 High-solid-content coating composition NO. 13 14 15 16 17 18 Hydroxy Hydroxy group-containing Acrylic resin (A-1) 43 45 45 43 45 45 group- acrylic resin (A) Acrylic resin (A-2) containing Acrylic resin (A-3) acrylic resin Acrylic resin (A-4) (A) Hydroxy group-containing Acrylic resin (A-1) acrylic resin (A) having alkoxysilyl group Hydroxy group-containing acrylic resin (D) Acrylic resin (D-1) Acrylic resin (D-2) Acrylic resin (D-3) Acrylic resin (D-4) Acrylic resin (D1-1) 5 5 Hydroxy group-containing polyester resin (B) Polyester resin (B-1) Polyester resin (B-2) Polyester resin (B-3) 5 Polyester resin (B-4) 8 Polyester resin (B-5) 8 5 Polyester resin (B-6) 8 Polyester resin (B-7) 8 Hydroxy group-containing polyester resin (E) Polyester resin (E-1) Polyester resin (E-2) Polyester resin (E-3) Polyisocyanate compound (C) Sumidur N3300 42 42 42 42 42 42 Melamine resin U-VAN 20SE60 5 5 5 5 5 5 Viscosity modifier SETALUX 61767 VX-60 0.3 0.3 0.3 0.3 0.3 0.3 Surface conditioner BYK-300 0.2 0.2 0.2 0.2 0.2 0.2 Solid content at the time of coating (%) 58% 58% 58% 58% 58% 58% Evaluation result Tukon hardness 11 11 11 12 11 11 Scratch resistance A A A A A A Water resistance A A A A A A Finished appearance (LW) 6 5 5 5 4 5 Finished appearance (SW) 17 15 15 15 15 14 Anti-after-tack property 92 88 88 91 88 88 (flip-flop value)

TABLE-US-00007 TABLE 7 Comparative Example 1 2 3 4 5 High-solid-content coating composition NO. 19 20 21 22 23 Hydroxy group-containing Hydroxy group-containing Acrylic resin (A-1) acrylic resin (A) acrylic resin (A) Acrylic resin (A-2) Acrylic resin (A-3) Acrylic resin (A-4) Hydroxy group-containing Acrylic resin (A-1) acrylic resin (A) having alkoxysilyl group Hydroxy group-containing acrylic resin (D) Acrylic resin (D-1) 45 Acrylic resin (D-2) 45 Acrylic resin (D-3) 45 Acrylic resin (D-4) 45 Acrylic resin (D1-1) 45 Hydroxy group-containing polyester resin (B) Polyester resin (B-1) 8 8 8 8 8 Polyester resin (B-2) Polyester resin (B-3) Polyester resin (B-4) Polyester resin (B-5) Polyester resin (B-6) Polyester resin (B-7) Hydroxy group-containing polyester resin (E) Polyester resin (E-1) Polyester resin (E-2) Polyester resin (E-3) Polyisocyanate compound (C) Sumidur N3300 42 42 42 42 42 Melamine resin U-VAN 20SE60 5 5 5 5 5 Viscosity modifier SETALUX 61767 VX-60 0.3 0.3 0.3 0.3 0.3 Surface conditioner BYK-300 0.2 0.2 0.2 0.2 0.2 Solid content at the time of coating (%) 58% 58% 58% 58% 58% Evaluation result Tukon hardness 12 10 9 13 8 Scratch resistance A B A B A Water resistance A B B A B Finished appearance (LW) 8 4 4 7 6 Finished appearance (SW) 19 13 14 18 18 Anti-after-tack property 86 84 85 86 93 (flip-flop value)

TABLE-US-00008 TABLE 8 Comparative Example 6 7 8 9 High-solid-content coating composition NO. 24 25 26 27 Hydroxy group-containing Hydroxy group-containing Acrylic resin (A-1) 45 45 45 45 acrylic resin (A) acrylic resin (A) Acrylic resin (A-2) Acrylic resin (A-3) Acrylic resin (A-4) Hydroxy group-containing Acrylic resin (A-1) acrylic resin (A) having alkoxysilyl group Hydroxy group-containing acrylic resin (D) Acrylic resin (D-1) Acrylic resin (D-2) Acrylic resin (D-3) Acrylic resin (D-4) Acrylic resin (D1-1) Hydroxy group-containing polyester resin (B) Polyester resin (B-1) Polyester resin (B-2) Polyester resin (B-3) Polyester resin (B-4) Polyester resin (B-5) Polyester resin (B-6) Polyester resin (B-7) Hydroxy group-containing polyester resin (E) Polyester resin (E-1) 8 Polyester resin (E-2) 8 Polyester resin (E-3) 8 8 Polyisocyanate compound (C) Sumidur N3300 42 42 42 42 Melamine resin U-VAN 20SE60 5 5 5 5 Viscosity modifier SETALUX 61767 VX-60 0.3 0.3 0.3 0.3 Surface conditioner BYK-300 0.2 0.2 0.2 0.2 Solid content at the time of coating (%) 58% 58% 58% 45% Evaluation result Tukon hardness 11 11 11 11 Scratch resistance A B A A Water resistance A A A A Finished appearance (LW) 8 9 11 5 Finished appearance (SW) 19 20 21 15 Anti-after-tack property 85 85 86 87 (flip-flop value)

[0250] Although the embodiment and examples of the present invention have been specifically described above, the present invention is not limited to the above embodiment, and various modifications can be made based on the technical idea of the present invention.

[0251] For example, the configurations, methods, processes, shapes, materials, numerical values, and the like described in the above embodiment and Examples are merely examples, and configurations, methods, processes, shapes, materials, numerical values, and the like different from those described above may be used as necessary.

[0252] The configurations, methods, processes, shapes, materials, numerical values, and the like in the above embodiment can be combined with each other without departing from the gist of the present invention.

[0253] The present application is based on Japanese Patent Application No. 2020-191307 filed on Nov. 18, 2020, and Japanese Patent Application No. 2021-066840 filed on Apr. 12, 2021, contents of which are incorporated herein by reference.