Patent ID: 7872085

Claim:
A biaxially oriented polypropylene film comprising: a polypropylene resin as a main component thereof; having a weight average molecular weight of 100,000 or more and 500,000 or less, the weight average molecular weight being determined by gel permeation chromatography, wherein the polypropylene resin has an isotactic proportion of 95% by mass or more and 99% by mass or less, the isotactic proportion being determined based on an amount of an extraction residue obtained by subjecting the polypropylene resin to sequential-extraction, an electric breakdown voltage level of the biaxially oriented polypropylene film is 0.3 KV/μm or more, and the biaxially oriented polypropylene film has a thickness of 1 to 7 μm, and at least one surface of the biaxially oriented polypropylene film has a protrusion volume of 2.0×10 4 μm 3 or more and 3.0×10 4 μm 3 or less, the protrusion using a super-depth surface profile measurement microscope by determining an average plane of the surface and an irradiation source of the super-depth surface profile measurement microscope and measuring a volume of protrusions projecting from the average plane.