Patent ID: 7141620

Claim:
A process for producing an aqueous polytetrafluoroethylene dispersion composition, comprising: adding from 2 to 20 wt %, based on the weight of polytetrafluoroethylene, of a nonionic surfactant, having an average molecular weight ranging from 450 to 800 and an inorganic/organic property ratio ranging from 1.07 to 1.50, and from 10 to 800 weight %, based on the weight of polytetrafluoroethylene, of water to an aqueous polytetrafluoroethylene polymer emulsion having a polytetrafluoroethylene content ranging from 10 to 50 wt % that is obtained by emulsion polymerization of tetrafluoroethylene in the presence of an anionic perfluorocarboxylate surfactant, thereby producing an aqueous polytetrafluoroethylene dispersion having a polytetrafluoroethylene content ranging from 1 to 40 wt %; obtaining a polytetrafluoroethylene-rich dispersion by permitting said aqueous polytetrafluoroethylene dispersion formed in the step above to separate into two aqueous phases, the supernatant phase being an aqueous phase substantially containing said anionic perfluorocarboxylate surfactant and the remaining phase being said polytetrafluoroethylene-rich aqueous dispersion; and separating the polytetrafluoroethylene-rich aqueous dispersion from the aqueous supernatant that contains said anionic perfluorocarboxylate surfactant.