Curable coating composition and coating film forming method

1. A coating film forming method

which comprises a step (1) of applying a curable coating on a substrate to be coated and

a step (2) including a stage of heating ahead of a stage of irradiating with ultraviolet ray, said curable coating comprising the curable coating which comprises (a) a component having two or more active methylene and/or active methine groups, (b) a component having two or more methacrylate and/or acrylate groups per one molecule, (c) a Michael reaction catalyst and (d) a photo-polymerizaton initiator.

2. The coating film forming method according to claim 1 ,

wherein said curable coating is a clear coating.

3. The coating film forming method according to claim 2 ,

wherein the substrate in said step (1) is formed with an uncured base coating film thereon in advance.

4. The coating film forming method according to claim 1 , wherein said component (a) is at least one species selected from the group consisting of reaction products of polyol with a carboxylic acid compound containing an active methylene group and/or an active methine group and/or a carboxylic acid ester containing an active methylene group and/or an active methine group, reaction products of a polyamine compound with diketene, acrylic resins containing an active methylene group/or an active methine group and reaction products of an isocyanate compound with a carboxylic acid compound containing an active methylene group and/or a carboxylic acid ester containing an active methylene group.

5. The coating film forming method according to claim 1 , wherein said component (b) is at least one species selected from the group consisting of (meth)acrylate esters of polyol, unsaturated polyester resins, epoxy(meth)acrylate resins, urethane(meth)acrylate resins, acrylic resins containing an α,β-unsaturated carbonyl group, polyether(meth)acrylate resins and silicone oligomers containing a (meth)acryloyl group.

6. The coating film forming method according to claim 1 , wherein said component (c) comprises at least one selected from the group consisting of alkaline metal hydroxides, alkaline metal alkoxides, quaternary ammonium hydroxides, quaternary ammonium carbonates, tertiary amines, guanidine, amidine, and tertiary phosphines.

7. The coating film forming method according to claim 1 , wherein said component (c) comprises a component (i) having an onium salt.

8. The coating film forming method according to claim 7 , wherein a cation of said onium salt is at least one selected from the group consisting of quaternary ammonium cations, quaternary phosphonium cations and tertiary sulfonium cations, and an anion of said onium salt is at least one selected from the group consisting of halide anions except for fluoride anions, carboxylate anions, sulfonate anions, sulfate anions, nitrate anions and phosphate anions.

9. The coating film forming method according to claim 7 , wherein said component (i) having the onium salt is a resin obtained by copolymerization of at least one monomer selected from the group consisting of quaternized aminoalkyl(meth)acrylates, quaternized amonoalkyl(meth)acrylamides, quaternary ammonium(meth)acrylates, quaternary phosphinoalkyl(meth)acrylates and quaternary phosphonium(meth)acrylates.

10. The coating film forming method according to claim 7 , wherein said component (c) comprises a component (ii) having an epoxy group.

11. The coating film forming method according to claim 10 , wherein said component (ii) having the epoxy group is a glycidyl compound, an alicyclic epoxy compound or an α-olefin epoxide.

12. The coating film forming method according to claim 10 , wherein said component (ii) having the epoxy group is a resin obtained by copolymerization of at least one monomer selected from the group consisting of glycidyl(meth)acrylates, β-methylglycidyl(meth)acrylates, glycidyl ether of 4-hydroxybutyl(meth)acrylate and (meth)acrylate of 3,4-epoxycyclohexanemethanol.

13. The coating film forming method according to claim 4 , wherein said component (b) is at least one species selected from the, group consisting of (meth)acrylate esters of polyol, unsaturated polyester resins, epoxy(meth)acrylate resins, urethane(meth)acrylate resins, acrylic resins containing an α,β-unsaturated carbonyl group, polyester(meth)acrylate resins and silicone oligomers containing a (meth)acryloyl group.

14. The coating film forming method according to claim 4 , wherein said component (c) comprises at least one selected from the group consisting of alkaline metal hydroxides, alkaline metal alkoxides, quaternary ammonium hydroxides, quaternary ammonium carbonates, tertiary amines, guanidine, amidine, and-tertiary phosphines.

15. The coating film forming method according to claim 5 , wherein said component (c) comprises at least one selected from the group consisting of alkaline metal hydroxides, alkaline metal alkoxides, quaternary ammonium hydroxides, quaternary ammonium carbonates, tertiary amines, guanidine, amidine, and tertiary phosphines.

16. The coating film forming method according to claim 4 , wherein said component (c) comprises a component (i) having an onium salt.

17. The coating film forming method according to claim 5 , wherein said component (c) comprises a component (i) having an onium salt.

18. The coating film forming method according to claim 16 , wherein a cation of said onium salt is at least one selected from the group consisting of quaternary ammonium cations, quaternary phosphonium cations and tertiary sulfonium cations, and an anion of said onium salt is at least one selected from the group consisting of halide anions except for an fluoride anion, carboxylate anions, sulfonate anions, sulfate anions, nitrate anions and phosphate anions.

19. The coating film forming method according to claim 17 , wherein a cation of said onium salt is at least one selected from the group consisting of quaternary ammonium cations, quaternary phosphonium cations and tertiary sulfonium cations, and an anion of said onium salt is at least one selected from the group consisting of halide anions except for an fluoride anion, carboxylate anions, sulfonate anions, sulfate anions, nitrate anions and phosphate anions.