Patent ID: 9025314
Filing Date: 2015-05-05
Classification: B29C,B29K,B32B,C08J,H01G,H01M,Y02E,Y10T

Abstract:
1. A biaxially oriented, single- or multi-layered porous film, the porosity of which is produced by conversion of β-crystalline polypropylene when the film is stretched, said film comprising at least one porous layer, this layer containing propylene homopolymer and/or propylene block copolymer and β-nucleation agent, wherein the film has a Gurley value of 50 to 400 s and shrinkage in the longitudinal direction of <5% at 100° C./1 hour, and a transverse shrinkage at 100° C./1 hour of <10% and the film having a tear strength of >30 N/mm 2 and the film further having a modulus of elasticity in the longitudinal direction of from 300 to 1800 N/mm 2 and in the transverse direction of from 500 to 3000 N/mm 2 .