PROCESS FOR PRODUCING MICROPOROUS POLYOLEFIN FILM

摘要

A process for producing a microporous polyolefin film which is used in applications such as water treatment and microfiltration membranes and has a relatively large pore diameter, a narrow pore diameter distribution, and excellent permeability, characterized by preparing a solution comprising 5 to 40 % by weight of a polyolefin composition containing an ultrahigh-molecular polyolefin having a weight-average molecular weight of 5x105 or higher and 95 to 60 % by weight of a solvent, extruding the solution through die lips, rapidly cooling the extrudate, and stretching the resultant sheet 1.01- to 1.4fold in terms of areal ratio.