New and improved process for the production of shaped articles from polymers and copolymers of tetrafluoroethylene

Abstract

Abstract Articles, e.g. rods, tubes, films and fibres, of tetrafluoroethylene polymers and copolymers are made by mixing the comminuted polymer with an organic heat-decomposable film-forming material, shaping and heating until the film-forming material is decomposed and the polymer coalesces. Film-forming materials specified are cellulose nitrate and acetate, ethyl cellulose, polyvinyl acetate, polyhydric alcohol-polybasic acid polyesters, polystyrene, gelatin and zein. Copolymers described are those with ethylene, isobutylene, chlorotrifluoroethylene, vinylidene chloride or fluoride and vinyl chloride or fluoride. Heating is preferably effected above the transition temperature of the p polymer (327 DEG C.) and in the presence of oxygen supplied by the atmosphere or by ammonium nitrate, and may be followed by quenching in cold water. The process may be used to coat asbestos fibres and sheets, carbon, mica, bentonite, glass and wires. Films and fibres made by the process and, if desired, oriented, may be wrapped on to articles for electric insulation and set by a heat treatment.

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