BIAXIALLY STRETCHED POLYOLEFIN FILM, METHOD FOR MANUFACTURING THE FILM, METAL-DEPOSITED POLYOLEFIN FILM, AND FILM CAPACITOR

摘要

PROBLEM TO BE SOLVED: To provide a biaxially stretched polyolefin film capable of manufacturing a capacitor endowed simultaneously with high-temperature voltage resistance and safety at the time of the impression of a high voltage.SOLUTION: The provided biaxially stretched polyolefin film is a biaxially stretched polyolefin film possessing a surface layer formed by a polypropylene resin composition including an isotactic polypropylene resin as a main component. The surface of the surface layer is a roughened surface on which fine unevenness is formed. The polypropylene resin composition includes polymethylpentene. The roughened surface satisfies relations of formulae (2) and (3): formula (2): -15 μm≤RSm-RSm≤3 μm; formula (3): 8 μm≤RSm≤25 μm. RSmand RSmare average lengths of curve elements on an occasion where the surface roughness of the roughened surface is measured with an optical interference-type non-contact surface shape analyzer; RSmis the measurement value along the lengthwise direction of the polyolefin film, whereas RSmis the measurement value along the widthwise direction thereof.