Patent ID: 6228287
Filing Date: 2001-05-08
Classification: B29C,H01B,H01C

Abstract:
A process for producing a positive temperature coefficient polymer composition comprising a crystalline polymer and an electrically conductive filler that is present in a predetermined proportion in the composition, the process comprising the steps of:blending the crystalline polymer with the electrically conductive filler into a first intimate admixture in proportions wherein the electrically conductive filler isless in the first intimate admixture than the predetermined proportion in the positive temperature coefficient polymer composition;extruding said first admixture to obtain an extruded pre-mix of crystalline polymer and filler;allowing the first admixture to solidify, and thereafter admixing the pre-mix with more electrically conductive filler in sufficient quantity to attain the predetermined proportion of filler in the composition, and melting and extruding the resulting mix to form said positive temperature coefficient polymer composition.