Patent ID: 6824865
Filing Date: 2004-11-30
Classification: B01D,B29D,B29K,H01M,Y02E,Y10T

Abstract:
A microporous polyolefin membrane with fine fibrils, comprising (A) a polyolefin having a weight-average molecular weight of 5Ã—105 or more or (B) fibrils a composition containing a polyolefin having a weight-average molecular weight of 5Ã—105 or more,said fibrils being connected to each other, wherein the average pore size of the membrane is 0.05 to 5 mm, and the crystal lamellas of the polyolefin which are inclined at an angle &thgr; of 80 to 100Â° to the plane constituting the membrane account for at least 40% of the total lamellas both on a section cut in the mechanical direction and on a section cut in the direction perpendicular to the mechanical direction and in the thickness direction.