FLUORORUBBER COPOLYMER

摘要

Provided is a fluororubber copolymer which comprises perfluoromethyl vinyl ether (PMVE) units and has excellent chemical resistance and low-temperature resistance, namely a fluororubber copolymer obtained by radical polymerization in the presence of a diiodide compound represented by the general formula (1): RI2 (1) (wherein R is a saturated fluoro- or chlorofluoro-hydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms) which comprises 40 to 70 mole % of vinylidene fluoride units, 10 to 25 mole % of tetrafluoroethylene units, and 20 to 35 mole % of perfluoromethyl vinyl ether units and contains 0.05 to 2 wt % of iodine based on the copolymer, and the vulcanizate of which exhibits TR70 of -20 to -30°C as determined according to ASTM D1329 TR test and a volume change of 8 to 20 % after the immersion in a 15:85 (by weight) mixture of Fuel C and methanol at 40 °C for 70 hours.