TETRAFLUOROETHYLENE/HEXAFLUOROPROPYLENE COPOLYMERS WITH HIGHER DRAWABILITY

摘要

The invention relates to a fluorinated ethylene propylene copolymer which is processed from the melt by fusion granulation and which consists essentially of monomer units of 78 to 95 wt. % tetrafluoroethylene, 5 to 22 wt. % hexafluoropropene and not more than 3 mol % fluorinated monomers that can be copolymerised with a mixture of tetrafluoroethylene and hexafluoropropene. Said copolymer has a molar ratio of weight average to number average of less than 2, has less than 80 unstable terminal groups per 1x106 carbon atoms and is produced by aqueous emulsion polymerisation. The copolymer is coagulated after polymerisation and then agglomerated. The agglomerate is isolated and dried to form a free flowing product, partial sintering being prevented. Sai d product is brought into contact with an effective amount of fluorine at a temperature between 60 ~C and the preliminary sintering temperature, whereby unstable terminal groups are converted into stable terminal groups. The fusi on granulate is advantageously treated with ammonia or a compound which liberat es ammonia, in water. The product can be used for coating wires and cables.