| 摘要 |
PROBLEM TO BE SOLVED: To obtain a film high in strength in a shutdown temperature range, capable of attaining a complete shutdown, excellent in shape retaining properties during melting, etc., by making the viscosity in a shutdown temperature range a specific value or higher than it in a drawn porous film. SOLUTION: This drawn porous polymer film has >=10<3> poise, preferably 10<3> -10<2> poise, more preferably 10<4> -10<6> poise viscosity in a shutdown temperature range. The porous film is preferably subjected to shutdown substantially by shrinkage in a shutdown temperature range and the shrinkage factor required for shutdown is generally several % or more, preferably 5-90 % in a shutdown temperature. The main shrinkage direction is preferably the longitudinal direction of the porous polymer film. This porous film is preferable as a separator for batteries and a permeable membrane for electrolytic capacitor, etc. |
