STRETCHED POLYTETRAFLUOROETHYLENE POROUS FILM HAVING ELASTICITY-RESTORING PROPERTY IN FILM THICKNESS DIRECTION, ITS MANUFACTURING METHOD AND USE OF POROUS FILM

摘要

PPROBLEM TO BE SOLVED: To provide a stretched polytetrafluoroethylene porous film having an improved elasticity-restoring property in the film thickness direction, and its manufacturing method. PSOLUTION: The stretched polytetrafluoroethylene porous film has a residual strain of at most 11.0% which is measured after a twenty-times repeated burden of a load necessary for thrusting a cylindrical stick, which has an outside diameter of at least 2 mm and at least 1.9 times the film thickness, a tip face with a smooth flat surface perpendicular to the axis and a longitudinal modulus of elasticity of at least 1.010SP4/SPkgf/mmSP2/SP, with the tip surface thereof ahead into the depth of 20% of the film thickness in the film thickness direction of the porous film at a distortion rate of 100%/min. The manufacturing method of the porous film comprises a step for compressing the stretched polytetrafluoroethylene porous film having a high stretch ratio. PCOPYRIGHT: (C)2006,JPO&NCIPI