Fluoride-containing polymer and composition containing same

Claim 1

A fluorine-containing polymer substantially comprising: monomeric units of (A), at least one fluorine-containing olefin of the formula: CF.sub.2 ═CXY wherein X is a hydrogen atom or a fluorine atom and Y is a hydrogen atom, a chlorine atom, a fluorine atom, a trifluoromethyl group, a difluoromethyl group, a C 1 -C 3 perfluoroalkoxy group or a group of the formula: --(CF.sub.2).sub.m COOM wherein m is an integer of 0 to 3 and M is a hydrogen atom, a C 1 -C 4 alkyl group, a sodium atom or a potassium atom but when X is a hydrogen atom, Y is always a hydrogen atom; monomeric units of (B), at least one C 4 -C 8 fluorine-containing diene(s) of the formula b--(CF 2 ) n --b, b--(CF 2 O) x --(CF 2 CF 2 O) y --(CF 2 CF(CF 3 )--O) z --CF 2 --b or ##STR5## wherein b is the same or a different group of the formula CF 2 ═CF--, CF 2 ═CH-- or CF 2 ═CFO--, n is an integer of 0 to 4, x is an integer of 0 to 3, y is an integer of 0 or 1 and z is an integer of 0 or 1, and x, y and z satisfy the relationship: < x+2y+3z+1≦4 but when n=0, z is other than the group of the formula CF 2 ═CFO--; (C), at least one iodine atom; and (D), at least one unsaturated --C 1 -C 8 -- fluoro or chlorofluorohydrocarbon group, the molar ratio of the diene (B) and the olefin (A) being from 1×10 -4 to 5×10 -2 , the iodine atom (C) being from 0.001 to 10% by weight based on the weight of the polymer and being bonded mainly to the end carbon atom(s) and the molar ratio of the group (D) and the olefin (A) being from 1×10 -5 to 5×10 -2 , said fluorine-containing polymer being produced by the process comprising the steps of polymerizing the component (A) in the presence of a radical producing source, excluding antinic ultraviolet light, and an iodine compound in which one or more of said iodine atoms (C) are bonded to said saturated or unsaturated fluoro or chlorofluorohydrocarbon group (D) and then further polymerizing with component (B) in the presence of the resulting product from the first polymerization.