Hoechst Aktiengesellschaft

Karl E Helf

Guenther Crass

Gunter Schloegl

Lothar Bothe

Thomas Wilhelm

A biaxially-oriented film, suitable for use as an electrically insulating film, is disclosed. The film is composed of a highly-pure electrical film raw material based on polyolefins, in particular propylene polymers, and contains carbonate particles as a neutralizing agent. The carbonate particles preferably have an absolute particle size of less than 10 micrometers, a mean particle diameter of less than 0.1 micrometer, a specific surface area of more than 30 m.sup.2 /g and a degree of whiteness of more than 90%. The film is used as a dielectric in a capacitor and shows improved electrical properties.

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Wiesbaden, Germany

Karl E Helf