Polyester film primed with organic acid salts

Claim 1

An oriented self-supporting polyester film having a thin continuous primer coating on one or both sides thereof, said coating consisting essentially of a salt selected from the group consisting of: (a) a water soluble alkali metal salt of an unsaturated fatty acid having from 10 to 18 carbon atoms and mixtures of such salts; or (b) a water soluble alkali metal salt of an alkyl sulfate having from 8 to 18 carbon atoms, and mixtures of such salts, said primer coating being present at a weight effective to improve the adhesion of printing inks to said film and wherein said film is prepared by melt extruding a substantially amorphous polyester film and thereafter orienting said film by stretching in one or two directions and heat setting said film, said primer coating being applied to said film as an aqueous solution prior to stretching in one direction, or subsequent to stretching in one direction but prior to stretching in a mutually perpendicular direction, or subsequent to stretching but prior to winding the oriented film, said film being subjected to a corona discharge treatment prior to the application of said primer coating, and wherein said film has a printing ink composition applied directly to said primer coating.