Patent ID: 7122608

Claim:
VDF polymerization process, optionally modified with small amounts, generally comprised between 0.1 and 10% by moles, of one or more fluorocontaining comonomers, for preparing VDF polymers showing improved levels of white index, carried out in the presence of a microemulsion comprising a (per)fluoropolyether having neutral end groups, or microemulsions of fluoropolyoxyalkylenes having hydrogen containing end groups and/or hydrogen-containing repeating units, or microemulsions of fluoropolyoxyalkylenes having hydrogen-containing end groups and/or hydrogen-containing repeating units and hydrocarbons C 1 –C 20 , of aliphatic, aromatic or mixed type, optionally containing halogens, said fluoropolyethers having number average molecular weight from 400 to 3000, and a surfactant based on perfluoropolyethers with a sodium carboxylate end group, said surfactant having a number molecular weight Mn comprised between 400–600, and having a distribution of molecular weight such that fractions having a number average molecular weight greater than 700 are not present or are present in amount of less than 5% by weight.