Microporous polyolefin membrane, separators and filters for battery using the same

摘要

PURPOSE: To provide an easily producible ultrafine porous polyolefin film having high mechanical strength and excellent drawability. ;CONSTITUTION: A sheet of a crosslinked polyolefin having a crosslinked structure to get a gel fraction of 5-70% is immersed in a good solvent for polyolefin at a temperature between Tm-50°C and Tm+50°C (Tm is melting point of the polyolefin resin). The immersed sheet is cooled and maintained in a state to prevent the shrinkage or drawn to obtain a polyolefin film having fine pores.;COPYRIGHT: (C)1994,JPO