Porous film
Provided is a porous film comprising a heat-resistant resin and two or more fillers, wherein a value of D 2 /D 1 is 0.15 or less where among values each obtained by measuring the average particle diameter of particles that constitute one of the two or more fillers, the largest value is let be D 1 and the second largest value is let be D 2 .
1. A porous film comprising a heat-resistant resin which is a nitrogen-containing aromatic polymer and two or more fillers, wherein a value of D 2 /D 1 is 0.15 or less where among values each obtained by measuring the average particle diameter of particles that constitute one of the two or more fillers, the largest value is D 1 and the second largest value is D 2 , wherein when the total weight of the fillers is 100, a ratio of a weight of the filler consisting of the particles with the average particle size of D 1 to a weight of the filler consisting of the particles with the average particle size of D 2 is from 30:70 to 70:30 and wherein the nitrogen-containing aromatic polymer is selected from the group consisting of aromatic polyamides, aromatic polyimides, and aromatic polyamideimides.
2. The porous film according to claim 1 which has a thickness that is not less than 1 μm and not more than 50 μm.
3. The porous film according to claim 1 , wherein when the weight of all the fillers is let be 100, the weight of the filler consisting of the particles having an average particle diameter of D 1 and the weight of the filler consisting of the particles having an average particle diameter of D 2 is 90 or more.
4. The porous film according to claim 1 , wherein D 1 is not less than 0.1 μm, and D 2 is less than 0.1 μm.
5. The porous film according to claim 1 , wherein D 1 is not more than 10 μm.
6. The porous film according to claim 4 , wherein D 1 is not less than 0.1 μm and not more than 1 μm, and D 2 is not less than 0.01 μm and less than 0.1 μm.
7. The porous film according to claim 1 , wherein all the particles constituting the fillers are alumina particles.
8. The porous film according to claim 1 , wherein part or all of the particles constituting the fillers are approximately spherical particles.
9. The porous film according to claim 7 , wherein when the overall weight of the porous film is let be 100, a weight of the fillers is not less than 20 and not more than 95.
10. A separator made of the porous film according to claim 1 .
11. The porous film according to claim 7 , wherein when the overall weight of the porous film is let be 100, a weight of the fillers is not less than 30 and not more than 90.
12. A porous film comprising a heat-resistant resin which is a nitrogen-containing aromatic polymer and two or more fillers, wherein a value of D 2 /D 1 is 0.15 or less wherein among values each obtained by measuring the average particle diameter of particles that constitute one of the two or more fillers, the largest value is D 1 and the second largest value is D 2 , wherein when the total weight of the fillers is 100, a ratio of a weight of the filler consisting of the particles with the average particle size of D 1 to a weight ratio of the filler consisting of the particles with the average particle size of D 2 is from 30:70 to 70:30, wherein the particles constituting the fillers are alumina particles.
13. The porous film according to claim 12 which has a thickness that is not less than 1 μm and not more than 50 μm.
14. The porous film according to claim 12 , wherein when the weight of all the fillers is 100, the weight of the filler consisting of the particles having an average particle diameter of D 1 and the weight of the filler consisting of the particles having an average diameter of D 2 is 90 or more.
15. The porous film according to claim 12 , wherein D 1 is not less than 0.1 μm and D 2 is less than 0.1 μm.
16. The porous film according to claim 12 , wherein D 1 is not more than 10 μm.
17. The porous film according to claim 15 , wherein D1 is not less than 0.1 μm and not more than 1 μm, and D2 is not less than 0.01 μm and less than 0.1 μm.
18. The porous film according to claim 12 , wherein part or all of the particles constituting the fillers are approximately spherical particles.
19. The porous film according to claim 12 , wherein when the overall weight of the porous film is 100, a weight of the fillers is not less than 20 and not more than 95.
20. A separator made of the porous film according to claim 12 .
21. The porous film according to claim 12 , wherein when the overall weight of the porous film is 100, a weight of the fillers is not less than 30 and not more than 90.