Coating composition for metallic substrates

A method of preventing corrosion of a metallic substrate, comprising

• providing a two-component coating composition comprising
• a film-forming component comprising
• a polymer component (I) comprising a film-forming polymer having functional groups selected from the group consisting of active hydrogen containing groups, epoxide groups, and mixtures thereof, and
• a hardener component (II) comprising a crosslinking agent having functional groups selected from the group consisting of isocyanate groups and amine groups, and
• a corrosion protection component consisting essentially of aluminum selected from the group consisting of nonleafing aluminum pigments and which is present in an amount of from 0.011 to 0.051 weight percent, based on the total nonvolatile film-forming component of the coating composition,
• mixing component (I) and component (II) together to from a mixed coating composition,
• applying the mixed coating composition to a metallic substrate, and
• curing the applied mixed coating composition to provide a coated metallic substrate, wherein the coated metallic substrate has a pass rating after 480 hours in salt spray per ASTM B117 and is sandable and recoatable.

A method of making a multilayer coating system, comprising

• providing a two-component primer coating composition comprising
• a film-forming component comprising
• a polymer component (I) comprising a film-forming polymer having functional groups selected from the group consisting of active hydrogen containing groups, epoxide groups, and mixtures thereof, and
• a hardener component (II) comprising a crosslinking agent having functional groups selected from the group consisting of isocyanate groups and amine groups,
• a corrosion protection component consisting essentially of aluminum selected from the group consisting of nonleafing aluminum pigments and which is present in an amount of from 0.011 to 0.051 weight percent, based on the total nonvolatile film-forming component of the coating composition,
• mixing component (I) and component (II) together to form a mixed primer composition,
• applying the mixed primer composition directly to a metal substrate to provide a coated metallic substrate,
• curing the coated metallic substrate to provide a primed metallic substrate which is both sandable and recoatable,
• applying to the primed metallic substrate one or more additional coating compositions, and
• curing the one or more additional coating compositions to provide a cured multilayer coating system.