Patent ID: 8877870

Claim:
A fluorinated elastic copolymer, which comprises repeating units (a) of tetrafluoroethylene, repeating units (b) of a fluorinated monomer having one polymerizable unsaturated bond, provided that tetrafluoroethylene is excluded, and repeating units (c) of a fluorinated monomer having at least two polymerizable unsaturated bonds, wherein the ratio (molar ratio) of the repeating units (a) to the repeating units (b) is (a)/(b)=63.4/36.6 to 80/20, and the proportion of the repeating units (c) of the total amount of the repeating units (a) and the repeating units (b) is from 0.01 to 1 mol %, wherein the fluorinated elastic copolymer comprises iodine atoms, bromine atoms or both iodine and bromine atoms at molecular terminals thereof, wherein the fluorinated monomer having one polymerizable unsaturated bond is a perfluoro(alkyl vinyl ether) represented by the formula CF 2 ═CFOR f1 , where R f1 is a C 1-3 perfluoroalkyl group which may have an etheric oxygen atom, and wherein the fluorinated monomer having at least two polymerizable unsaturated bonds is a monomer represented by the formula R 14 ((O) a CF═CF 2 ) b , where a is 0 or 1, b is an integer of from 2 to 6, and R 14 is a C 1-25 b-valent perfluoro saturated hydrocarbon group which may have an etheric oxygen atom.