Patent ID: 9138690
Filing Date: 2015-09-22
Classification: B01D,B29C,B29K,B29L,C08J,Y10T

Abstract:
1. A method for producing one of an air-permeable filter and an air-permeable fabrics material comprising, as a constituent material, an air-permeable composite sheet, said method comprising: filling pores of a porous polytetrafluoroethylene (PTFE) sheet with a hardenable material solution comprising a hardenable material; hardening or semi-hardening the porous PTFE sheet filled with the hardenable material solution to increase compression resistance and mechanical strength of the air-permeable composite sheet; and expanding the hardened or semi-hardened porous PTFE sheet, after said hardening or semi-hardening step, to increase porousness of the hardened or semi-hardened porous PTFE sheet, wherein the expanding step re-generates continuous holes through the composite sheet, and wherein the hardenable material is present on the parts of the surface of the pores of the PTFE sheet and the PTFE sheet is exposed in other parts to provide water repellency on the exposed other parts.