abstract |
Provided is a porous film having a shutdown (SD) characteristic in order to ensure the safety of a battery while having a breakdown (BD) characteristic of a polypropylene resin. A laminated porous film in which at least two porous layers are laminated, wherein one layer of the porous layer includes a polypropylene resin and the other layer includes the polypropylene resin. It is a shutdown layer made of a composition having a crystal melting peak temperature lower than the crystal melting peak temperature of the resin composition of the layer, and has β activity and / or β crystal forming ability. [Selection figure] None |