Method for producing fluorinated copolymer solution, and coating composition

A method for producing a fluorinated copolymer solution, the method comprising polymerizing a monomer mixture comprising a fluoro-olefin (A), a monomer (B) having a crosslinkable group and a monomer (C) having no fluorine atom and no crosslinkable group, in the presence of an organic solvent, and a compound having two or more piperidyl groups to form a fluorinated copolymer solution,

• wherein the molar ratio of the total molar amount of piperidyl groups contained in the compound to the total molar amount of monomers in the monomer mixture, is from 0.00105 to 0.00380, wherein the compound having two or more piperidyl groups is formula (3):
• wherein to the fluorinated copolymer solution obtained is added a polyisocyanate and a curing catalyst to obtain a coating composition and the coating composition is applied as a coating film on a glass substrate, the resulting coating film has a cure degree of at least 70% as determined by the difference of the mass of the coating film before and after being immersed in acetone for 1 hour under reflux.