| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a laminated porous film having excellent air permeability and mechanical strength, and having a shut-down characteristic. <P>SOLUTION: In the laminated porous film in which at least two porous layers are laminated, the two layers contain polypropylene resins. One of the two layers contains a thermoplastic resin having a peak crystal melting temperature of 100°C to 150°C, while the other one layer does not include the thermoplastic resin having the peak crystal melting temperature of 100°C to 150°C, and has β activity and/or β crystal formation power. On the other hand, the two layers contain the polypropylene resins, and thermoplastic resins each having the peak crystal melting temperature of 100°C to 150°C, wherein contents of the two thermoplastic resins of these two layers are made to differ from each other, and the laminated porous film has the β activity and/or the β crystal formation power. <P>COPYRIGHT: (C)2009,JPO&INPIT |
