MICROPOROUS POLYPROPYLENE FILM AND PROCESS FOR PRODUCING THE SAME

摘要

A microporous polypropylene film exhibiting enhanced film forming properties in beta-crystal technique; a microporous polypropylene film of markedly lowered specific gravity; a microporous polypropylene film of highly enhanced permeability; and a process for producing these microporous polypropylene films. There is provided a microporous polypropylene film comprising a polypropylene whose Trouton's ratio is specified. Further, there is provided a microporous polypropylene film comprising a polypropylene whose main chain skeleton contains long-chain branching. Still further, there is provided a microporous polypropylene film comprising a polypropylene whose formula of relationship between melt tension and melt flow rate is specified. Still further, there is provided a microporous polypropylene film comprising a polypropylene whose profile of film in-plane intensity distribution in azimuthal angle direction of (-113) face as identified by X-ray diffractometry is specified.