Coating compositions for aluminum beverage cans and methods of coating same

1. A method, comprising the steps of:

receiving a coating composition that includes an emulsion polymerized latex polymer that comprises a reaction product of an ethylenically unsaturated monomer component polymerized in the presence of an aqueous dispersion of a salt of an acid- or anhydride-functional polymer, wherein the ethylenically unsaturated monomer component includes an oxirane group-containing monomer and at least 40 wt-% of the ethylenically unsaturated monomer component comprises one or more monomers selected from alkyl acrylates and methacrylates, and wherein the coating composition is substantially free of bound BPA;

spray applying the coating composition onto an interior surface of an aluminum beverage can including a body portion and a bottom end portion; and

curing the coating composition to form a continuous cured coating.

2. The method of claim 1 , wherein the cured coating exhibits a global extraction result of less than 50 ppm.

3. The method of claim 1 , wherein the beverage can includes a dome apex and the cured coating shows no craze after the outside of the dome apex is subjected to a 12 in-lbs reverse impact.

4. The method of claim 1 , wherein the cured coating 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.

5. The method of claim 1 , wherein the ethylenically unsaturated monomer component includes at least 20 wt-% of a vinyl aromatic compound.

6. The method of claim 1 , wherein the oxirane-group containing monomer is present in an amount of more than 5 wt-% to 30 wt-%, based on the weight of the ethylenically unsaturated monomer component.

7. The method of claim 1 , wherein the oxirane group-containing monomer comprises glycidyl methacrylate, glycidyl acrylate, or a mixture of glycidyl methacrylate and glycidyl acrylate.

8. The method of claim 1 , wherein the ethylenically unsaturated monomer component does not include acrylamide, methacrylamide, N-isobutoxymethyl acrylamide, or N-butoxymethyl acrylamide.

9. The method of claim 1 , wherein the ethylenically unsaturated monomer component does not include any vinyl acrylamide monomers.

10. The method of claim 1 , wherein the ethylenically unsaturated monomer component includes both an alkyl acrylate and an alkyl methacrylate.

11. The method of claim 1 , wherein at least 50 wt-% of the ethylenically unsaturated monomer component is used in making the latex polymer, based on the total weight of ethylenically unsaturated monomer component and salt of the acid- or anhydride-functional polymer.

12. The method of claim 1 , wherein the salt of an acid- or anhydride-functional polymer comprises a salt of an acid- or anhydride-functional polymer and a tertiary amine.

13. The method of claim 1 , wherein the coating composition does not include a phenoplast crosslinker.

14. The method of claim 1 , further comprising filling the coated beverage can with a beverage product.

15. The method of claim 1 , wherein the coating composition is completely free of bound BPA and aromatic glycidyl ether compounds.

16. A coated beverage can resulting from the method of claim 1 .

17. The method of claim 1 , wherein the acid- or anhydride-functional polymer comprises an organic-solution polymerized acid- or anhydride-functional acrylic polymer.

18. The method of claim 17 , wherein the cured coating exhibits a metal exposure of less than 1 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.

19. The method of claim 17 , wherein the cured coating exhibits a global extraction result of less than 10 ppm.

20. The method of claim 17 , wherein the cured coating 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.

21. The method of claim 17 , wherein the ethylenically unsaturated monomer component includes at least 20 wt-% of styrene.

22. The method of claim 17 , wherein the oxirane-group containing monomer is present in an amount of more than 5 wt-% to 9 wt-%, based on the weight of the ethylenically unsaturated monomer component.

23. The method of claim 17 , wherein the ethylenically unsaturated monomer component includes ethyl acrylate.

24. The method of claim 23 , wherein the ethylenically unsaturated monomer component includes styrene.

25. The method of claim 17 , wherein the ethylenically unsaturated monomer component includes ethyl acrylate, styrene, and glycidyl methacrylate.

26. The method of claim 17 , wherein the acid- or anhydride-functional monomers included in the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer consists of methacrylic acid.

27. The method of claim 1 , wherein the cured coating exhibits a metal exposure of less than 2 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.

28. The method of claim 27 , wherein the cured coating exhibits a global extraction result of less than 1 ppm.

29. The method of claim 1 , wherein the salt of an acid- or anhydride-functional polymer comprises a salt of an acid- or anhydride-functional alkyd resin, a salt of an acid- or anhydride-functional polyester resin, or a salt of an acid- or anhydride-functional polyurethane resin.

30. The method of claim 1 , wherein the salt of an acid- or anhydride-functional polymer comprises a salt of an acid- or anhydride-functional acrylic polymer.

31. The method of claim 30 , wherein the acid- or anhydride-functional acrylic polymer comprises more than 15 wt-% acid- or anhydride-functional monomers, based on the weight of polymerizable unsaturated monomer used to generate the acid- or anhydride-functional acrylic polymer.

32. The method of claim 30 , wherein the acid- or anhydride-functional acrylic polymer comprises more than 30 wt-% acid- or anhydride-functional monomers, based on the weight of polymerizable unsaturated monomer used to generate the acid- or anhydride-functional acrylic polymer.

33. The method of claim 30 , wherein the polymerizable unsaturated monomers used to generate the acid- or anhydride-functional acrylic polymer includes methacrylic acid and does not include acrylic acid.

34. A method, comprising the steps of:

receiving a coating composition that includes an emulsion polymerized latex polymer that comprises a reaction product of an ethylenically unsaturated monomer component polymerized in the presence of an aqueous dispersion of a salt of an organic-solution polymerized acid- or anhydride-functional acrylic polymer and an amine, and wherein the ethylenically unsaturated monomer component includes an oxirane-group containing monomer and at least 40 wt-% of the ethylenically unsaturated monomer component consists of one or more monomer types selected from alkyl acrylates and methacrylates;

spray applying the coating composition onto an interior surface of an aluminum beverage can including a body portion and a bottom end portion; and

curing the coating composition to form a cured coating.

35. The method of claim 34 , wherein the coating composition is substantially free of bound BPA and aromatic glycidyl ether compounds.

36. The method of claim 35 , wherein the cured coating exhibits a metal exposure of less than 2 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.

37. The method of claim 36 , wherein the cured coating exhibits a global extraction result of less than 10 ppm.

38. The method of claim 36 , wherein the cured coating 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.

39. The method of claim 35 , wherein the cured coating exhibits a metal exposure of less than 1 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.

40. The method of claim 35 , wherein the cured coating exhibits a global extraction result of less than 50 ppm.

41. The method of claim 35 , wherein the cured coating exhibits a global extraction result of less than 1 ppm.

42. The method of claim 35 , wherein the beverage can includes a dome apex and the cured coating shows no craze after the outside of the dome apex is subjected to a 12 in-lbs reverse impact.

43. The method of claim 35 , wherein the cured coating 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.

44. The method of claim 35 , wherein the ethylenically unsaturated monomer component includes at least 20 wt-% of styrene.

45. The method of claim 35 , wherein the ethylenically unsaturated monomer component includes at least 20 wt-% of a vinyl aromatic compound.

46. The method of claim 35 , wherein the oxirane-group containing monomer is present in an amount of more than 5 wt-% to 30 wt-%, based on the weight of the ethylenically unsaturated monomer component.

47. The method of claim 35 , wherein the oxirane-group containing monomer is present in an amount of more than 5 wt-% to 9 wt-%, based on the weight of the ethylenically unsaturated monomer component.

48. The method of claim 35 , wherein the oxirane group-containing monomer comprises glycidyl methacrylate, glycidyl acrylate, or a mixture of glycidyl methacrylate and glycidyl acrylate.

49. The method of claim 35 , wherein the ethylenically unsaturated monomer component includes ethyl acrylate.

50. The method of claim 49 , wherein the ethylenically unsaturated monomer component includes styrene.

51. The method of claim 35 , wherein the ethylenically unsaturated monomer component includes ethyl acrylate, styrene, and glycidyl methacrylate.

52. The method of claim 35 , wherein the ethylenically unsaturated monomer component does not include acrylamide, methacrylamide, N-isobutoxymethyl acrylamide, or N-butoxymethyl acrylamide.

53. The method of claim 35 , wherein the ethylenically unsaturated monomer component does not include any vinyl acrylamide monomers.

54. The method of claim 35 , wherein the ethylenically unsaturated monomer component includes both an alkyl acrylate and an alkyl methacrylate.

55. The method of claim 35 , wherein at least 50 wt-% of the ethylenically unsaturated monomer component is used in making the latex polymer, based on the total weight of ethylenically unsaturated monomer component and salt of the organic-solution polymerized acid- or anhydride-functional acrylic polymer and an amine.

56. The method of claim 35 , wherein the amine comprises a tertiary amine.

57. The method of claim 35 , wherein the acid- or anhydride-functional acrylic polymer comprises more than 15 wt-% acid- or anhydride-functional monomers, based on the weight of polymerizable unsaturated monomer used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer.

58. The method of claim 35 , wherein the acid- or anhydride-functional acrylic polymer comprises more than 30 wt-% acid- or anhydride-functional monomers, based on the weight of polymerizable unsaturated monomer used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer.

59. The method of claim 35 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer includes methacrylic acid and does not include acrylic acid.

60. The method of claim 35 , wherein the acid- or anhydride-functional monomers included in the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer consists of methacrylic acid.

61. The method of claim 35 , wherein the coating composition does not include a phenoplast crosslinker.

62. The method of claim 35 , further comprising filling the coated beverage can with a beverage product.

63. The method of claim 35 , wherein the coating composition is completely free of bound BPA and aromatic glycidyl ether compounds.

64. The method of claim 35 , wherein at least 50 wt-% of the ethylenically unsaturated monomer component consists of one or more monomer types selected from alkyl acrylates and methacrylates.

65. A coated beverage can resulting from the method of claim 35 .

66. A coated article comprising:

an aluminum beverage can including a body portion and a bottom end portion; and

a cured coating on an interior surface of the aluminum beverage can, wherein the coating is formed from a coating composition that includes an emulsion polymerized latex polymer that comprises a reaction product of an ethylenically unsaturated monomer component polymerized in the presence of an aqueous dispersion of a salt of an acid- or anhydride-functional polymer and an amine, wherein the ethylenically unsaturated monomer component includes an oxirane-group containing monomer and at least 40 wt-% of the ethylenically unsaturated monomer component consists of one or more monomer types selected from alkyl acrylates and methacrylates, and wherein the coating composition is substantially free of bound BPA and aromatic glycidyl ether compounds.

67. The coated article of claim 66 , wherein the coating is formed from a spray applied coating.

68. The coated article of claim 67 , wherein the acid- or anhydride-functional acrylic polymer used to from the salt of an acid- or anhydride-functional polymer and an amine was formed by polymerizing unsaturated monomers in the presence of a free radical initiator.

69. The coated article of claim 68 , wherein the beverage can contains a beverage product.