POLYESTER FILM WITH SMOOTH AND HIGHLY ADHESIVE SURFACE AND METHOD OF MAKING SAME

摘要

Disclosed is a biaxially stretched polyester film having a modified surface with an excellent bondability, in which both the surface smoothness and the slip characteristic, which are contradictory to each other, are satisfactory. This biaxially stretched polyester film has a multiplicity of ultra-fine protrusions which are an integral part of the film and dyeable with osmic acid. The film is prepared by subjecting an undrawn or drawn polyester sheet to a plasma treatment and then drawing the treated sheet at least once. The film is valuable as a base for a magnetic recording medium.