POROUS POLYPROPYLENE FILM PRODUCTION METHOD AND POROUS POLYPROPYLENE FILM AND ELECTRICITY STORAGE DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a porous polypropylene film production method suitable for a separator for an electricity storage device, and capable of achieving sufficient performance even under a high temperature environment when it is used for the separator for an electricity storage device. ! SOLUTION: Provided is the porous polypropylene film production method including a step for drawing a non-drawn sheet including a β crystal nucleus agent whose average circle-equivalent diameter is 150 nm or less and standard deviation of an equivalent circle diameter is 70 nm or less to at least one axis. ! COPYRIGHT: (C)2015,JPO&INPIT