Dielectric films with increased voltage endurance

Abstract

A dielectric film with improved voltage endurance is disclosed. The dielectric film is provided with an aluminum oxide powder dust coating which increases the life of the film by improving the voltage endurance. A film comprising mica reinforced with polyester and/or glass is especially useful in the manufacture of insulating tapes and cloths found in electrical devices. Best voltage endurance is provided by fumed aluminum oxide particles which are in the colloidal size range and which are more than 99.5% pure.

Dependencies are inferred from the claim text.