Coating Compositions for Aluminum Beverage Cans and Methods of Coating Same

A method, comprising the steps of:

• providing a latex-based acrylic coating composition that comprises a surfactant, a crosslinker, and a latex;
• wherein the latex includes one or more polymers formed from ethylenically unsaturated monomers;
• wherein the ethylenically unsaturated monomers include one or more monomers selected from alkyl acrylates and methacrylates, one or more acid-functional monomers, optionally one or more oxirane-group containing monomers, and optionally one or more difunctional (meth)acrylate monomers;
• wherein acrylamide, methacrylamide, N-isobutoxymethyl acrylamide, or N-butoxymethyl acrylamide are not present in ethylenically unsaturated monomers polymerized in aqueous medium to form the latex;
• and wherein the coating composition is not made using PVC compounds and is substantially free of mobile and bound bisphenol A;
• spray applying the coating composition onto an interior surface of an aluminum beverage can including a body portion and an end portion;
• and
• curing the coating composition to form a cured coating that exhibits (i) a global extraction result of less than 50 ppm and (ii) a metal exposure of less than 3 mA on average when the can is filled with 1% NaCl in deionized water and tested pursuant to the Initial Metal Exposure test method disclosed herein.

An interior can coating composition comprising a latex-based acrylic coating composition that comprises a surfactant, a crosslinker, and a latex;

• wherein the latex includes one or more polymers formed from ethylenically unsaturated monomers;
• wherein the ethylenically unsaturated monomers include one or more monomers selected from alkyl acrylates and methacrylates, one or more acid-functional monomers, optionally one or more oxirane-group containing monomers, and optionally one or more difunctional (meth)acrylate monomers;
• wherein acrylamide, methacrylamide, N-isobutoxymethyl acrylamide, or N-butoxymethyl acrylamide are not present in ethylenically unsaturated monomers polymerized in aqueous medium to form the latex;
• wherein the coating composition is not made using PVC compounds and is substantially free of mobile and bound bisphenol A;
• and wherein the coating composition, when spray applied onto an interior of a 12 ounce two-piece drawn and ironed aluminum beverage can at 120 to 130 milligrams per can coating weight and cured at 188° C. to 199° C. (measured at the can dome) for 30 seconds, exhibits:
• (i) a global extraction result of less than 50 ppm;
• and
• (ii) a metal exposure of less than 3 mA on average when the can is filled with 1% NaCl in deionized water and tested pursuant to the Initial Metal Exposure test method disclosed herein.