| 摘要 |
PROBLEM TO BE SOLVED: To provide a porous film having high gas permeability and strength, especially a porous film having a strength and a gas permeability sufficient for the use as a separator for a battery. SOLUTION: A porous film having a gas permeability of 10-1,000 sec/100 ml per 25μm thick and a pin puncture strength of 2-8 N per 25μm thick is produced by preparing a raw film from a resin composition produced by compounding 100 pts.mass of a polyolefin resin (melting point; Tm°C) with 2-25 pts.mass of a filler, drawing the raw film by a single or multiple stage low-temperature drawing at -20 to +50°C at a draw ratio of 1.1-3.0, and further drawing the film by a≥2-stage high-temperature drawing at (Tm-70) to (Tm-5)°C at a draw ratio of 1.1-3.0. COPYRIGHT: (C)2008,JPO&INPIT |
