POROUS POLYPROPYLENE FILM

摘要

In order to provide a porous polypropylene film in which the ratio of change in air permeability is small and the initial air-permeating property is satisfactory even under high temperature environment, a porous polypropylene film is proposed, satisfying the following conditions (1) and (2) regarding air-permeability (Pa1) at 20° C. and air-permeability (Pa2) after heating at 95° C. for one hour: (1) The Pa1 is 800 seconds/100 ml or less (2) The ratio of change in air permeability calculated by the formula below is 120% or less Ratio of change in air permeability (%)=(Pa2/Pa1)×100