General Electric Company

John W Eustance

Stanley Young Hobbs

Emilie L Carley

A thin polypropylene film with improved surface impregnation properties for dielectric fluids is disclosed. The film has one predetermined textured surface consisting essentially of fibroids intertwined and overlapping, and coextensive and uniform over its continuous length and is characterized by a space factor of above about 5%.

Textured surface polypropylene film

An improved process of producing a predetermined textured surface on a polypropylene film is disclosed including the steps of extruding the polypropylene into a stalk, cooling the stalk to crystallize the polypropylene, passing the stalk through a heating zone and biaxially stretching the stalk into a thin film. The stalk emanating from the extruder has a section primarily temperature controlled and correlated to the stalk velocity to cause extensive, continuous and uniform spherulite formation with a predominantly type III polypropylene crystal structure on the outer surface of the stalk, which upon subsequent inflation of the stalk causes the desired texture to occur.

A metallized polypropylene film with improved surface impregnation properties for dielectric fluids is disclosed. The film has one predetermined textured surface and is characterized by a space factor of above about 5% and has an electrical conductive metallic coating on one surface.

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South Glens Falls, NY, United States of America

John W Eustance