POROUS FILM, BATTERY AND SEPARATOR THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a porous film which has high thickness precision even if the thickness is extremely thin. SOLUTION: The porous film is composed of a resin composite film consisting of at least high density polyethylene resin (A) and filler material (B), wherein holes are formed on the resin composite film by extending it. Average value of the thickness of the porous film is 5 to 40μm, and maximum value and minimum value are within the limits of the average value±25%. Inorganic filler which consists of barium sulfate grains or calcium carbonate grains having average grain diameter from 0.1 to 25μm is used as the filler material (B). The filler material (B) of 50 to 400 part by mass is combined with the high density polyethylene resin (A) of 100 part by mass. COPYRIGHT: (C)2006,JPO&NCIPI