A PROCESS FOR PREPARING A MICROPOROUS POLYOLEFIN MEMBRANE

摘要

A process for preparing a microporous polyolefin membrane comprises stretching a thick sheet comprising a polyolefin resin and a solvent to a thin membrane by a bi-oriented stretch, wherein said bi-oriented stretch is a sequential bi-oriented stretch comprising a machine direction stretch followed by a transverse direction stretch and the transverse direction stretch ratio is over 1.3 times of the machine direction stretch ratio. The microporous polyolefin membrane prepared by the process of the present invention possesses good ventilation property and high tensile strength.