Nonaqueous electrolyte secondary battery separator
As a nonaqueous electrolyte secondary battery separator having a transverse direction/machine direction crease recovery angle ratio of close to 1, a nonaqueous electrolyte secondary battery separator is provided that includes a polyolefin porous film having a ratio of a 60-degree gloss in an machine direction to a 60-degree gloss in a transverse direction which ratio is not less than 1.00.
1. A nonaqueous electrolyte secondary battery separator comprising:
a polyolefin porous film,
the polyolefin porous film having a ratio of a 60-degree gloss in a machine direction to a 60-degree gloss in a transverse direction of not less than 1.00.
2. The nonaqueous electrolyte secondary battery separator according to claim 1 , further comprising:
an insulating porous layer.
3. The nonaqueous electrolyte secondary battery separator according to claim 2 , wherein the insulating porous layer contains at least one resin selected from the group consisting of a polyolefin, a (meth)acrylate-based resin, a fluorine-containing resin, a polyamide-based resin, a polyester-based resin, and a water-soluble polymer.
4. The nonaqueous electrolyte secondary battery separator according to claim 3 , wherein
the polyamide-based resin is aramid resin.
5. A nonaqueous electrolyte secondary battery member comprising:
a positive electrode;
a nonaqueous electrolyte secondary battery separator according to claim 1 ; and
a negative electrode,
wherein the positive electrode is adjacent to the nonaqueous electrolyte secondary battery separator and the negative electrode is adjacent to the nonaqueous electrolyte secondary battery separator on a side opposite the positive electrode.
6. A nonaqueous electrolyte secondary battery comprising:
a nonaqueous electrolyte secondary battery separator according to claim 1 .
7. A nonaqueous electrolyte secondary battery member comprising:
a positive electrode;
a nonaqueous electrolyte secondary battery separator according to claim 2 ; and
a negative electrode,
wherein the positive electrode is adjacent to the nonaqueous electrolyte secondary battery separator and the negative electrode is adjacent to the nonaqueous electrolyte secondary battery separator on a side opposite the positive electrode.
8. A nonaqueous electrolyte secondary battery comprising:
a nonaqueous electrolyte secondary battery separator according to claim 2 .