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.

主权项

1. A biaxially stretched polypropylene film for a capacitor, which has projections on both surfaces thereof, and has a thickness t1 (μm) of 4 to 20 μm, wherein when one of both the surfaces that is smaller in SRz is represented by a surface A and the other surface is represented by a surface B, wherein:
800≦SRzB≦1,300 (nm), 0.1≦SRzA/SRzB≦0.8, PBmin≧100 (nm), PBmax≦1,500 (nm), and 0.4≦PB450-750/PB≦0.7, are satisfied and wherein:
SRzA: a ten-point average roughness (nm) of the surface A,SRzB: a ten-point average roughness (nm) of the surface B,PBmin: a minimum projection height (nm) of the surface B,PBmax: a maximum projection height (nm) of the surface B,PB450-750: the number of projections which are present in the surface B and each have a height of 450 nm or more but less than 750 nm per 0.1 mm2 (number/0.1-mm2), andPB: the total number of projections present in the surface B per 0.1 mm2 (number/0.1-mm2).