a crystalline polyester film or sheet coated with a priming composition consisting essentially of a carboxyl group - containing copolyester , wherein the carboxyl groups are introduced either by treatment of the terminal hydroxyl groups of the copolyester with a dicarboxylic acid anhydride or by pyrolysis of the copolyester . such primer compositions form continuous wet films and dry coatings and provide surfaces receptive to a variety of surface finishes such as further polymer coatings and inks . further , the primer - coated polyester can be recycled and can be used in applications where the coating is in contact with food articles .