| 摘要 |
PROBLEM TO BE SOLVED: To provide a polypropylene film which can be rolled with constant spacing during device winding processing and gives a safe condenser having excellent high-temperature voltage-withstanding characteristics during voltage application.SOLUTION: A polypropylene film includes a plurality of fine unevennesses each having a crater shape to give the film a rough surface. When upper parts of the fine unevennesses are projected on the surface to obtain a projected image, a plurality of crater projected images G each comprising a pair of arcs 30a and 30b are observed on the projected image. When the sum of the lengths of the pair of arcs 30a and 30b is set as L, the whole length of a virtual ring including the pair of arcs 30a and 30b is set as Lin each crater projected image G and the ratio (L/L) is evaluated, the average α of the ratios (L/L) is 0.3 or more. |
