HIGH STRENGTH POROUS FILM OF POLYPROPYLENE AND PROCESS FOR PRODUCING SAME

摘要

Disclosed is a high strength porous film of polypropylene which comprises predominantly a polypropylene resin and possesses the following physical properties: (1) a tensile strength of at least 35 MPa in machine direction (MD) and transverse direction (TD); (2) a porosity of not more than 80%; and (3) a moisture permeability of at least 20 g/m2 day. The porous film may be produced by stretching or thermally treating a biaxially stretched polypropylene film. The high strength porous film may be used for wrapping food or as a separator of a secondary battery.