Method for producing fluoroolefin copolymer solution and method for producing coating composition

1. A method for producing a fluoroolefin copolymer solution, the method comprising:

subjecting a fluoroolefin and a monomer other than the fluoroolefin to a solution polymerization in an organic solvent in the presence of potassium carbonate and hydrotalcite

wherein a mass ration of the potassium carbonate to the hydrotalcite is from 4/96 to 80/20.

2. The method of claim 1 ,

wherein the organic solvent comprises at least one organic solvent selected from the group consisting of a ketone solvent, an ether/ester solvent and a third-category organic solvent stipulated in Industrial Safety and Health Act.

3. The method of claim 2 , wherein the organic solvent further comprises an alcohol solvent having at most 4 carbon atoms.

4. The method of claim 1 ,

wherein a total mass of the potassium carbonate and the hydrotalcite is from 0.5 to 10 mass % of a total mass of the fluoroolefin and the monomer.

5. The method of claim 1 , wherein the monomer is comprises cyclohexyl vinyl ether.

6. The method of claim 1 ,wherein the monomer comprises a hydroxyalkyl vinyl ether.

7. The method of claim 1 , further comprising:

filtrating a reaction solution obtained from the solution polymerization to remove an insoluble component.

8. The method of claim 1 , wherein a chromaticity of the fluoroolefin copolymer solution is from 30 to 60% of a chromaticity of a comparative solution obtained by an otherwise identical process comprising solution polymerization in the presence of potassium carbonate but not hydrotalcite.

9. The method of claim 1 , wherein a number of fluorine atoms in the fluoroolefin is 2 or more.

10. The method of claim 9 , wherein the number of fluorine atoms in the fluoroolefin is from 2 to 6.

11. The method of claim 1 , wherein the fluoroolefin comprises tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, hexafluoropropylene, or any combination thereof.

12. The method of claim 1 ,

wherein the monomer other than the fluoroolefin comprises a structure of formula 1:

CH 2 =CX ( CH 2 ) n - Q - R—Y   (1),

X is a hydrogen atom or a methyl group,

n is 0 or 1,

Q is an oxygen atom, —C(O)O— or —O(O)C—,

R is an optionally branched, optionally cyclic C 2-20 alkylene group, and

Y is a hydrogen atom or a crosslinkable functional group.

13. The method of claim 1 , wherein the organic solvent is substantially free of any aromatic ring.

14. The method of claim 1 , wherein the hydrotalcite has a particle diameter of from 5 to 500 μm.

15. The method of claim 1 , wherein the potassium carbonate has a particle diameter of from 100 to 1,000 μm.

16. The method of claim 1 , wherein the mass ratio of the potassium carbonate to the hydrotalcite is from 10/90 to 50/50.

17. The method of claim 1 , wherein the solution polymerization is in the presence of a polymerization initiator.

18. A method for producing a coating composition, comprising:

producing a fluoroolefin copolymer solution by the method of claim 1 , and then

blending a second coating material blend component to the fluoroolefin copolymer solution.

19. The method of claim 18 , wherein the second coating material blend component is at least one selected from the group consisting of an organic solvent, a curing agent, a colorant and a resin other than the fluoroolefin copolymer.