Process for producing a colored polyester film

Abstract

A polyester film can be dyed by coating the film with a layer of a dye mixture which is a suspension of at least one disperse dyestuff in a solution of a thickener in water and which has a viscosity of no more than 500 centipoise, preferably 5-50 centipoise, at ambient temperature, followed by heating to cause the dyestuff to migrate from the layer into the film. The coating process is preferably reverse gravure printing. The process can be used to prepare films which contain one or more dyestuffs in one surface region of the film and one or more different dyestuffs, for example an ultraviolet absorber, in the other surface region of the film. The dyed films show good resistance to fading when exposed to light and are useful for example as automobile window films.

Dependencies are inferred from the claim text.