| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyolefin microporous film suitably used as a separator for a battery and to provide a method for producing the same. SOLUTION: The polyolefin microporous film comprises a polyolefin composition containing≥1.0 wt.% of an ultra high molecular weight polyolefin having≥5×10<SP>5</SP>viscosity average molecular weight and has 25-60% porosity and a porous structure of a branch and trunk-like fibril. The area of the porous part observed on the surface by a scanning electron microscope amounts to≥80% and, in the porous part, the average diameter of trunk-like fibril is 0.01-0.05μm and the average diameter of branch-like fibril crossing the trunk is 0.01-0.03μm. COPYRIGHT: (C)2006,JPO&NCIPI |
