Patent ID: 8323837

Claim:
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.