| 摘要 |
PROBLEM TO BE SOLVED: To provide a microporous polyolefin film which can provide a separator for nonaqueous secondary batteries having excellent shutdown properties when compounded with a heat-resistant porous layer composed of a heat-resistant resin. SOLUTION: The polyolefin microporous film includes an MD<SB>105</SB>/TD<SB>105</SB>of 1.3-3.0 when the thermal shrinkage at 105°C in the machine direction and thermal shrinkage at 105°C in the machine vertical direction are taken as MD<SB>105</SB>and TD<SB>105</SB>, respectively. COPYRIGHT: (C)2011,JPO&INPIT
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