Patent ID: 8124667

Claim:
A method for the stabilization of a grafted fluoropolymer by radiation grafting onto said fluoropolymer of a graftable metal salt, comprising the following steps: a) melt blending the fluoropolymer comprising a poly(vinylidene fluoride) (PVDF) homopolymer or copolymer with a compound containing a single C═C double bond and at least one polar functional group that is not a carboxylic acid salt functional group, and a stabilizer of at least one graftable metal salt having one of the following formulae: (CH 2 ═CH—COO − ) n M n+ (CH 2 ═C(CH 3 )—COO − ) n M n+ (CH 2 ═CH-Q-COO − ) n M n+ where Q denotes an optionally substituted, linear or cyclic, aliphatic or optionally substituted aromatic group, n is 1 or 2, and M denotes a metal cation of valence n, which may be chosen from Ca 2+ , Na + and Zn 2+ , wherein said subscript n and valence n represent the same number; b) forming the blend obtained at a) into films, sheets, granules or powder; c) subjecting the products from step b) to photon (γ) or electron (β) irradiation with a dose of between 0.5 and 15 Mrad, to obtain a fluoropolymer onto which said graftable compound is grafted and also said graftable metal salt is grafted; and d) subjecting the products from step c) to a washing and/or a degassing operation, wherein an optional antioxidant stabilizer is blended into the fluoropolymer either before or after the irradiation step.