PURPOSE: To obtain a soft fluororesin by a safe polymerization method using a solution of an unsaturated peroxide which can be stored and does not adversely influence the polymerization, by using a specific solvent.
CONSTITUTION: A monomer comprising a fluoromonomer is radical- copolymerized with a monomer which has both a double bond and a peroxy bond in the molecule and has been dissolved III R1COOR2 [wherein R1 is H, methyl, or t-butyl and R2 is (chlorrne- or fluorine-substituted) methyl, ethyl, n-propyl, or isopropyl], C2HxClyF2 [wherein (x), (y), and (z) each is 1 to 4, provided that (x+y+z)=6], C3HxC1yF2 [wherein (x), (y) and (z) each is 1-6, provided that (x+y+z):8], C4HxClyFz [wherein (x), (y), and (z) each is 1-8, provided that (x+y+f):10], methylene chloride, or 1,1,1-trichloroethane. Thus, an elastic fluorocopolymer is obtained which contains peroxy bonds in the molecule and has a glass transition temp. not higher than room temp. A fluoromonomer which gives a crystalline polymer having a melting point of 130°C or higher is grafted onto the fluorocopolymer.
ISHIHARA AKIRA
KAWAMURA KATSUNORI
