POLYPROPYLENE FILM FOR OIL-IMPREGNATED CAPACITOR AND CAPACITOR CONSTITUTED OF THE FILM

摘要

PROBLEM TO BE SOLVED: To increase the breakdown voltage and thermal resistance, by making mesopentad separation ratio at least a specified value, and making percentage of thermal contraction in the longitudinal direction and percentage of thermal contraction in the widthwise direction at most specified values. ;SOLUTION: Mesopentad separation ratio of a polypropylene film is set at least about 98.0%. Percentage of thermal contraction in the longitudinal direction is set at most 3.0%, and percentage of thermal contraction in the widthwise direction is set at most 1.0%. In the polypropylene film, cyclic epoxy araldite such as 3,4-epoxycyclohexylmethyl and 3,4-epoxycyclohexanecarboxylate is contained at least about 0.005 wt.% and at most about 0.060 wt.%. The film is formed by using a tenter method or an inflation method. As a result, a polypropylene film excellent in withstand voltage and thermal resistance is manufactured, and an oil-impregnated capacitor excellent in long term stability is manufactured by using the above film at least as a part of dielectrics.;COPYRIGHT: (C)1999,JPO