To increase high-temperature machining property and to improve electrical characteristics such as the breakdown voltage characteristics of a capacitor at a high temperature by making specific a heat shrinkage rate in the longitudinal direction, a heat shrinkage rate in the width direction, a strength on 100% extension in the longitudinal direction, and a mesopentad percentage.
In a polypropylene film, a heat shrinkage rate in the longitudinal direction is set to approximately 3.0% or less, and that is the width direction is set to approximately 0% or more and approximately 1.0% or less. Also, strength on 100% extension ion the longitudinal direction of the film is set to approximately 8.0 kg/mm2 or more. Further, the mesopentad percentage of the polypropylene film is set to approximately 98.0% or more. Also, at least one surface of the polypropylene film is metallized. At this time, surface treatment such as corona discharge treatment is made to the surface where the film is metallized, thus improving a deposition machining property and a high-temperature machining property in the manufacturing process of a capacitor, simplifying the manufacturing process, and improving the electrical characteristics of withstand voltage and the like.
ODA AKIRA
MORIGUCHI ISAMU
