| 摘要 |
PROBLEM TO BE SOLVED: To solve problems of the conventional porous film which has extremely high void ratio, tending to result in reduced elastic modulus due to such a high void ratio, and whose void ratio becomes higher when a draw ratio is increased to promote molecular orientation and to enhance an elastic modulus, resulting in rather reduced elastic modulus despite the intention; and to provide a porous film having a high elastic modulus by appropriately controlling voids generated during stretching. SOLUTION: The porous film includes at least one layer of mixed resin containing a polypropylene-based resin and a thermoplastic resin having a crystal melting peak temperature or a glass transition temperature of <120°C, and hasβactivity. COPYRIGHT: (C)2010,JPO&INPIT |
