| 摘要 |
PROBLEM TO BE SOLVED: To provide the polyester film for a capacitor which suitably obtains excellent dielectric strength and insulation resistance even under severe capacitor machining condition. SOLUTION: This polyester film for a capacitor is a biaxially oriented film consisting principally of polyethylene terephthalate, the number of surface projections of 2000 to 500 nm measured by the three-dimensional surface roughness meter is 200 to 2000/nm2, and the thermal elongation quantity Z(%) of the film at 90 to 140 deg.C C satisfies 3.9×10-4.(t-40)2>=Z>=1.2×10-8.(t-40)4, where (t) is the measured temperature ( deg.C). |
