Microporous Membrane, Battery Separator, and Battery
A microporous membrane according to the present invention is a microporous membrane containing a copolymerized high density polyethylene and a high density polyethylene, wherein a content of an α-olefin unit having 3 or more carbon atoms in the microporous membrane is 0.01 mol % or more and 0.6 mol % or less, and a viscosity average molecular weight of the microporous membrane is less than 300,000. In addition, a battery separator according to the present invention contains the above microporous membrane. Further, a battery according to the present invention contains the above battery separator.
1. A microporous membrane comprising a copolymerized high density polyethylene and a high density polyethylene,
wherein a content of an α-olefin unit having 3 or more carbon atoms in the microporous membrane is 0.12 mol % or more and 0.56 mol % or less,
wherein a viscosity average molecular weight of the microporous membrane is 180,000 or more and less than 300,000,
wherein the copolymerized high density polyethylene has a melt index of 0.8 to 5, and a content of the α-olefin unit having 3 or more carbon atoms in the copolymerized high density polyethylene is 0.4 to 0.8 mol %, and
wherein the high density polyethylene has a viscosity average molecular weight of 150,000 or more and less than 500,000.
2. The microporous membrane according to claim 1 , wherein a molecular weight distribution Mw/Mn of the microporous membrane is 2 or more and 8 or less.
3. The microporous membrane according to claim 1 , wherein the microporous membrane does not comprise a high density polyethylene having a viscosity average molecular weight of 500,000 or more.
4. The microporous membrane according to claim 1 , further comprising polypropylene.
5. The microporous membrane according to claim 1 , wherein a dynamic friction coefficient of the microporous membrane is less than 0.2.
6. A battery separator comprising the microporous membrane according to claim 1 .
7. A battery comprising the battery separator according to claim 6 .
8. The microporous membrane according to claim 1 , wherein a fuse response time is 10 seconds or less.
9. The microporous membrane according to claim 8 , wherein, in a battery windability test, a proportion of samples, in which pin contact portions are displaced by 2 mm or more from an initial position before pin removal due to being pulled by the pin, is 1/100 or less.
10. The microporous membrane according to claim 1 , wherein the viscosity average molecular weight of the microporous membrane is ≤290,000.
11. The microporous membrane according to claim 10 , wherein a molecular weight distribution Mw/Mn of the microporous membrane is 2 or more and 8 or less.
12. The microporous membrane according to claim 10 , wherein the microporous membrane does not comprise a high density polyethylene having a viscosity average molecular weight of 500,000 or more.
13. The microporous membrane according to claim 10 , further comprising polypropylene.
14. The microporous membrane according to claim 10 , wherein a dynamic friction coefficient of the microporous membrane is less than 0.2.
15. The microporous membrane according to claim 10 , wherein a fuse response time is 10 seconds or less.
16. The microporous membrane according to claim 15 , wherein, in a battery windability test, a proportion of samples, in which pin contact portions are displaced by 2 mm or more from an initial position before pin removal due to being pulled by the pin, is 1/100 or less.
17. A battery separator comprising the microporous membrane according to claim 10 .
18. A battery comprising the battery separator according to claim 17 .