Tripolymer primer for vinyl resin dispersions and steel coated with a film thereof

Claim 1

A SHEET OF STEEL HAVING ADHERED THERETO A FILM OF PRIMER COMPRISING A COPOLYMER OF MONOMER COMPONENTS CONSISTING ESSENTIALLY OF VINYL TOULENE, ACRYLONITRILE AND AN ETHYLENICALLY UNSATURATED CARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF ACRYLIC ACID, METHACRYLIC ACID AND ITACONIC ACID, THE PROPORTIONS OF SAID MONOMER COMPONENETS ON A MOL EQUIVALENT BASIS BEING WITHIN THE AREA A-C-D-F-A ON THE TRIANGULATION OF FIGURE 1, AND COPOLYMER HAVING ARELATIVE VISCOSITY MEASURED AT 25* C. IN A 1 GRAM/100 ML. SOLVENT SOLUTION IN DIMETHYL FORMAMIDE OF FROM 1.4-3.5 AND A TOPCOAT ADHERED TO SAID PRIMER FILM, SAID TOPCOAT COMPRISING A FUSED LAYER OF A POLYMER HAVING A MOLECULAR WEIGHT ABOVE 20,000 AND SELECTED FROM THE GROUP CONSISTING OF POLYVINYL CHLORIDE, COPOLYMERS OF VINYL CHLORIDE WITH UP TO 10% BY WEIGHT OF VINYL ACETATE AND COPOLYMERS OF VINYL CHLOWITH UP TO 10% BY WEIGHT OF VINYLIDENE CHLORIDE.