DIELECTRIC RESIN COMPOSITION FOR FILM CAPACITOR, PROCESS FOR PRODUCING SAME, AND FILM CAPACITOR

摘要

To increase the heat resistance of a film capacitor, a cured article obtained by curing a mixed solution of a polyvinyl acetal having a hydroxyl group content of 10% to 38% by weight, the number of carbon atom repetitions of the polyvinyl acetal being 100 or more, and a polyisocyanate having an isocyanate content of 1% to 50% by weight is used as a material of dielectric resin films (3, 4) arranged between first and second counter electrodes (5, 6) facing each other. At least the polyvinyl acetal is subjected to high-pressure homogenization in which a shearing force is applied in such a manner that a pressure applied to the polyvinyl acetal is 50 MPa or more when the first organic material is passed through a path having a diameter of 0.125 mm and a length of 5 mm, so that the solubility is increased to allow a curing reaction to proceed uniformly. The cured article has a glass transition temperature of 130°C or higher and a breakdown voltage of 350 V/µm or more,