Process for producing porous polytetrafluoroethylene film
AssigneeDaikin Industries, Ltd.
InventorsShinji Tamaru, Hirofumi Nishibayashi, Katsutoshi Yamamoto, Osamu Tanaka, Osamu Inoue
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Abstract
A porous PTFE film having a thin thickness and good permeability is produced by coating an emulsion of polytetrafluoroethylene on a substrate surface, in particular, a porous polytetrafluoroethylene substrate which has not been heated at a melting point of unsintered polytetrafluoroethylene or higher, heating the coated substrate at a temperature not lower than a melting point of sintered polytetrafluoroethylene to semi-sinter polytetrafluoroethylene, optionally removing the semi-sintered polytetrafluoroethylene film from the substrate, and then stretching the semi-sintered film at least in one direction.
Claims10
A process for producing a porous polytetrafluoroethylene film comprising coating an emulsion of polytetrafluoroethylene on a substrate surface, heating the coated substrate at a temperature not lower than a melting point of sintered polytetrafluoroethylene to semi-sinter polytetrafluoroethylene, optionally removing the semi-sintered polytetrafluoroethylene film from the substrate, and then stretching the semi-sintered film at least in one direction.
A process for producing a multi-layer porous polytetrafluoroethylene film comprising at least two layers having different average pore sizes, which process comprises coating an emulsion of polytetrafluoroethylene on a porous polytetrafluoroethylene substrate which has not been heated at a melting point of unsintered polytetrafluoroethylene or higher, heating a coated polytetrafluoroethylene substrate at a temperature not lower than a melting point of sintered polytetrafluoroethylene to semi-sintered polytetrafluoroethylene, and stretching a composite of the coated film and the substrate at least in one direction.
Dependencies are inferred from the claim text.