Coating Compositions for Aluminum Beverage Cans and Methods of Coating Same

Abstract

A coating composition for a food or beverage can that includes an emulsion polymerized latex polymer formed by combining an ethylenically unsaturated monomer component with an aqueous dispersion of a water-dispersible polymer.

What is claimed is: 
     
         1 - 20 . (canceled) 
     
     
         21 . An interior can coating composition comprising a latex-based acrylic coating composition that comprises a latex that 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, and one or more oxirane-group containing monomers; and wherein the coating composition is not made using PVC compounds and is substantially free of mobile and bound bisphenol A. 
     
     
         22 . The coating composition of  claim 21 , 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 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. 
     
     
         23 . The coating composition of  claim 22 , 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 a global extraction result of less than 50 ppm. 
     
     
         24 . The coating composition of  claim 22 , 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 no adhesion failure when tested pursuant to ASTM D-3359-Test method B after retort in deionized water for 90 minutes at a heat of 121° C. and a corresponding pressure. 
     
     
         25 . The coating composition of  claim 21 , 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, gives a metal exposure of less than 3.5 mA when tested pursuant to the Metal Exposure after Drop Damage test disclosed herein. 
     
     
         26 . The coating composition of  claim 21 , 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. 
     
     
         27 . The coating composition of  claim 26 , wherein vinyl acrylamides or vinyl methacrylamides are not present in ethylenically unsaturated monomers polymerized in aqueous medium to form the latex. 
     
     
         28 . The coating composition of  claim 21 , wherein the coating composition is completely free of mobile and bound bisphenol A and aromatic glycidyl ether compounds. 
     
     
         29 . The coating composition of  claim 21 , wherein the ethylenically unsaturated monomers include one or more alkyl acrylates and one or more alkyl methacrylates. 
     
     
         30 . The coating composition of  claim 21 , wherein the ethylenically unsaturated monomers include glycidyl (meth)acrylate, butyl (meth)acrylate, and styrene. 
     
     
         31 . The coating composition of  claim 30 , wherein the ethylenically unsaturated monomers include glycidyl methacrylate, butyl acrylate, and styrene. 
     
     
         32 . The coating composition of  claim 30 , wherein the ethylenically unsaturated monomers include methacrylic acid. 
     
     
         33 . The coating composition of  claim 30 , wherein the ethylenically unsaturated monomers include one or more hydroxy alkyl (meth)acrylate. 
     
     
         34 . The coating composition of  claim 21 , wherein at least 40 wt-% of the ethylenically unsaturated monomers polymerized in aqueous medium to form the latex comprise one or more monomers selected from alkyl acrylates and methacrylates. 
     
     
         35 . The coating composition of  claim 21 , wherein the ethylenically unsaturated monomers include a vinyl aromatic compound, and wherein the vinyl aromatic compound comprises at least 20 wt-% of the ethylenically unsaturated monomers polymerized in aqueous medium to form the latex. 
     
     
         36 . The coating composition of  claim 21 , wherein the ethylenically unsaturated monomer component includes one or more difunctional (meth)acrylate monomers. 
     
     
         37 . The coating composition of  claim 21 , wherein the coating composition includes a surfactant. 
     
     
         38 . The coating composition of  claim 37 , wherein the coating composition includes a crosslinker. 
     
     
         39 . The coating composition of  claim 21 , wherein the coating composition includes a phenoplast crosslinker. 
     
     
         40 . The coating composition of  claim 21 , wherein the coating composition includes a strong acid. 
     
     
         41 . The method of  claim 40 , wherein the strong acid comprises dodecylbenzene sulphonic acid. 
     
     
         42 . The method of  claim 41 , wherein the strong acid is present in an amount of from at least 0.01% by weight to no greater than 3% by weight, based on the weight of nonvolatile material. 
     
     
         43 . An interior can coating composition comprising a latex-based acrylic coating composition that comprises a latex that 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, and one or more oxirane-group containing 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 completely 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. 
 
     
     
         44 . The coating composition of  claim 43 , wherein the ethylenically unsaturated monomers include one or more alkyl acrylates and one or more alkyl methacrylates. 
     
     
         45 . The coating composition of  claim 43 , wherein the ethylenically unsaturated monomers include glycidyl (meth)acrylate, butyl (meth)acrylate, and styrene. 
     
     
         46 . The coating composition of  claim 45 , wherein the ethylenically unsaturated monomers include glycidyl methacrylate, butyl acrylate, and styrene. 
     
     
         47 . The coating composition of  claim 45 , wherein the ethylenically unsaturated monomers include methacrylic acid. 
     
     
         48 . The coating composition of  claim 43 , 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 no adhesion failure when tested pursuant to ASTM D-3359-Test method B after retort in deionized water for 90 minutes at a heat of 121° C. and a corresponding pressure. 
     
     
         49 . The coating composition of  claim 43 , 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, gives a metal exposure of less than 3.5 mA when tested pursuant to the Metal Exposure after Drop Damage test disclosed herein. 
     
     
         50 . The coating composition of  claim 43 , wherein vinyl acrylamides or vinyl methacrylamides are not present in ethylenically unsaturated monomers polymerized in aqueous medium to form the latex. 
     
     
         51 . The coating composition of  claim 43 , wherein the coating composition includes a strong acid. 
     
     
         52 . The coating composition of  claim 51 , wherein the strong acid comprises dodecylbenzene sulphonic acid. 
     
     
         53 . The coating composition of  claim 51 , wherein the strong acid is present in an amount of from at least 0.01% by weight to no greater than 3% by weight, based on the weight of nonvolatile material. 
     
     
         54 . An interior can coating composition comprising a latex-based acrylic coating composition that comprises a latex that includes one or more polymers formed from ethylenically unsaturated monomers; wherein the ethylenically unsaturated monomers include glycidyl (meth)acrylate, butyl (meth)acrylate, and styrene; 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. 
 
     
     
         55 . The coating composition of  claim 54 , 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. 
     
     
         56 . The coating composition of  claim 54 , wherein the ethylenically unsaturated monomers include glycidyl methacrylate, butyl acrylate, and styrene. 
     
     
         57 . The coating composition of  claim 54 , wherein at least 50 wt-% of the ethylenically unsaturated monomers polymerized in aqueous medium to form the latex comprise one or more monomers selected from alkyl acrylates and methacrylates. 
     
     
         58 . The coating composition of  claim 54 , wherein the ethylenically unsaturated monomers include a vinyl aromatic compound, and wherein the vinyl aromatic compound comprises at least 20 wt-% of the ethylenically unsaturated monomers polymerized in aqueous medium to form the latex. 
     
     
         59 . The coating composition of  claim 54 , wherein vinyl acrylamides or vinyl methacrylamides are not present in ethylenically unsaturated monomers polymerized in aqueous medium to form the latex. 
     
     
         60 . The coating composition of  claim 54 , wherein the ethylenically unsaturated monomers include methacrylic acid. 
     
     
         61 . The coating composition of  claim 54 , wherein the ethylenically unsaturated monomers include one or more hydroxy alkyl (meth)acrylate. 
     
     
         62 . The coating composition of  claim 54 , wherein the coating composition includes a surfactant. 
     
     
         63 . The coating composition of  claim 62 , wherein the coating composition includes a crosslinker. 
     
     
         64 . The coating composition of  claim 54 , wherein the coating composition includes a phenoplast crosslinker. 
     
     
         65 . The coating composition of  claim 54 , wherein the coating composition includes a strong acid. 
     
     
         66 . The coating composition of  claim 65 , wherein the strong acid comprises dodecylbenzene sulphonic acid. 
     
     
         67 . The coating composition of  claim 65 , wherein the strong acid is present in an amount of from at least 0.01% by weight to no greater than 3% by weight, based on the weight of nonvolatile material.