Primer coating, polyester film having a primer coating, and a process for coating film

摘要

A polyester film coated with a novel primer coating and overcoated with one or more gelatin-aziridine coatings makes an excellent photographic film as well as for other suitable purposes like reprographic film, x-ray film, etc. The primer coating has about 85-90% by weight of a water-dispersible copolyester and about 1-15% by weight of an anionic surfactant. The water-dispersible copolyester contains about 80-98 mol % of at least one dicarboxylic acid or its ester equivalent; about 1-20 mol % of a sulfomonomer containing a sulfonate group attached to a dicarboxylic nucleus; and about 100 mol % of at least one glycol having 2-11 carbon atoms. The gelatin-aziridine coating contains about 0.5 to 100% by weight of aziridine, based on the weight of the gelatin. The gelatin-aziridine coating is sufficient to provide adhesion to or serve as a photographic gelatin coating and the aziridine being sufficient to bond the gelatin to the primed film. The gelatin-aziridine coating may constitute a single uniformly blended layer, or separate layers of gelatin and of aziridine with each layer diffused into the other. A process for producing a film useful as a photographic substrate is also disclosed.