Patent ID: 6939495

Claim:
A method of manufacturing a pipe, said method comprising extruding thermoprocessable copolymers of TFE to form said pipe, wherein said thermoprocessable copolymers of TFE consist essentially of: (a) from 4.5 to 8.5% by weight of perfluoromethylvinylether (PMVE); (b) from 0.3 to 1.6% by weight of a perfluorodioxole of formula: wherein: Y=F, OR f , R f wherein R f is a perfluoroalkyl having from 1 to 5 carbon atoms; X 1 and X 2 , equal to or different from each other, are—F or—CF 3 ; (c) TFE, forming the remaining part to 100%; said copolymer having: a number of ionic end groups lower than 4×10 −4 mol/Kg of polymer; flex life values higher than 20,000 in a MFI range (measured at 372° C. with a 5 Kg load) comprised between 1 and 5; release values of F − ions on the polymer in pellet and on the finished manufactured article lower than 1 ppm by weight with respect to the polymer weight; release values of F − ions lower than 1 ppm on extruded manufactured articles, both at low and high extrusion rate of the polymer.