BIAXIALLY STRETCHED POLYPROPYLENE FILM FOR CAPACITOR, METALLIZED FILM, AND FILM CAPACITOR

摘要

Provided is a biaxially stretched polypropylene film for capacitors which has high withstand voltage characteristics when used as a dielectric for capacitors and which has highly suitable processability into elements. The biaxially stretched polypropylene film for capacitors has projections on both surfaces and has a thickness (t1, µm) of 4-20 µm. When one of the surfaces is expressed by surface A and the other by surface B, all of the following relationships are satisfied. 800=SRzB=1,300 (nm) 0.1=SRzA/SRzB=0.8 PBmin=100 (nm) PBmax=1,500 (nm) 0.4=PB450-750/PB=0.7 In the relationships, SRzA is the 10-point average roughness of surface A (nm), SRzB is the 10-point average roughness of surface B (nm), PBmin is the minimum projection height of surface B (nm), PBmax is the maximum projection height of surface B (nm), PB450-750 is the total number of projections which are present on surface B and which each have a height of 450 nm or greater but less than 750 nm, per 0.1 mm2 (projections/0.1 mm2), and PB is the total number of projections present on surface B per 0.1 mm2 (projections/0.1 mm2).