Patent ID: 8491991
Filing Date: 2013-07-23
Classification: B29C,B29K,C08J,Y10T

Abstract:
1. A microporous polypropylene film consisting essentially of not less than 97 wt % polypropylene with respect to a total amount of monomers of all polymers in the film, said polypropylene comprising polypropylene having a Trouton ratio of not less than 30, said film having 1) β-crystal activity, 2) a specific gravity of 0.2 to 0.4, 3) a liquid paraffin permeating time of 0.1 seconds/25 μm to 60 seconds/25 μm, 4) a heat shrinkage ratio at 105° C. in a longitudinal direction of the film of no greater than 5%, 5) a Trouton ratio of not less than 6 and 6) a Gurley air permeability of 50 sec/100 ml to 300 sec/100 ml.