Coating compositions for aluminum beverage cans and methods of coating same

1. An inside spray beverage can coating composition, comprising:

an emulsion polymerized latex polymer that is prepared from ingredients including:

a salt of an acid- or anhydride-functional acrylic polymer and an amine;

an ethylenically unsaturated monomer component that includes a vinyl aromatic compound and an oxirane-group containing monomer; and

water;

wherein the coating composition is substantially free of bound bisphenol A, and wherein the coating composition is suitable for forming an inside spray coating of a two-piece drawn and ironed aluminum beverage can.

2. The coating composition of claim 1 , wherein the oxirane-group containing monomer is present in an amount of 0.1 wt-% to 30 wt-%, based on the weight of the ethylenically unsaturated monomer component.

3. The coating composition of claim 1 , 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.

4. The coating composition of claim 1 , wherein the ethylenically unsaturated monomer component comprises a vinyl aromatic component that is at least 20 wt-% of the ethylenically unsaturated monomer component, and wherein the vinyl aromatic component comprises one or more aromatic compounds.

5. The coating composition of claim 1 , wherein the vinyl aromatic compound is styrene.

6. The coating composition of claim 1 , wherein the ethylenically unsaturated monomer component comprises at least 20 wt-% of styrene.

7. The coating composition of claim 1 , wherein the ethylenically unsaturated monomer component includes ethyl acrylate.

8. The coating composition of claim 1 , wherein the ethylenically unsaturated monomer component includes ethyl acrylate, styrene, and glycidyl methacrylate.

9. The coating composition of claim 1 , wherein the ethylenically unsaturated monomer component includes butyl acrylate, styrene, and glycidyl methacrylate.

10. The coating composition of claim 1 , wherein the coating composition is made without using PVC compounds.

11. The coating composition of claim 1 , wherein the emulsion polymerized latex polymer is substantially free of bound aromatic glycidyl ether compounds.

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

13. The coating composition of claim 1 , wherein the ethylenically unsaturated monomer component does not include any vinyl acrylamide monomers.

14. The coating composition of claim 1 , wherein at least 25 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 acrylic polymer.

15. The coating composition of claim 1 , wherein the acid- or anhydride-functional acrylic polymer has a number average molecular weight of 1,500 to 50,000.

16. The coating composition of claim 1 , wherein the acid- or anhydride-functional acrylic polymer has a number average molecular weight of 2,000 to 20,000.

17. The coating composition of claim 1 , wherein the acid- or anhydride-functional acrylic polymer has an acid number of at least 40.

18. The coating composition of claim 1 , wherein at least 40 wt-% of the ethylenically unsaturated monomer component comprises one or more monomers selected from alkyl acrylates and methacrylates.

19. The coating composition of claim 1 , 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 10 ppm.

20. The coating composition of claim 1 , 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, shows no craze after the outside of the dome apex of the can is subjected to a 12 in-lbs reverse impact.

21. The coating composition of claim 1 , 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.

22. The coating composition of claim 1 , wherein at least 10 wt-% of the salt of the acid- or anhydride-functional acrylic polymer 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 acrylic polymer.

23. The coating composition of claim 1 , wherein the coating composition is made without using PVC compounds.

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

25. The coating composition of claim 24 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include methacrylic acid, styrene, and ethyl acrylate.

26. The coating composition of claim 24 , 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.

27. The coating composition of claim 24 , wherein the oxirane group-containing monomer comprises glycidyl methacrylate.

28. The coating composition of claim 24 , wherein the coating composition is substantially free of bound aromatic glycidyl ether compounds.

29. The coating composition of claim 24 , 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.

30. The coating composition of claim 24 , wherein the organic-solution polymerized acid- or anhydride-functional acrylic polymer has an acid number of at least 40.

31. The coating composition of claim 24 , wherein the organic-solution polymerized acid- or anhydride-functional acrylic polymer has an acid number of at least 100.

32. The coating composition of claim 24 , 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.

33. The coating composition of claim 24 , 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.

34. The coating composition of claim 24 , wherein at least 40 wt-% of the ethylenically unsaturated monomer component comprises one or more monomers selected from alkyl acrylates and methacrylates.

35. The coating composition of claim 24 , 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 1 ppm.

36. The coating composition of claim 24 , 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 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 coating composition of claim 24 , 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, shows no craze after the outside of the dome apex of the can is subjected to a 12 in-lbs reverse impact.

38. The coating composition of claim 24 , 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.

39. The coating composition of claim 24 , wherein at least 10 wt-% of the salt of the organic-solution polymerized acid- or anhydride-functional acrylic polymer 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 acrylic polymer.

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

41. The coating composition of claim 40 , wherein at least 60 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 acrylic polymer.

42. The coating composition of claim 41 , wherein the acid- or anhydride-functional acrylic polymer has an acid number of at least 100.

43. The coating composition of claim 1 , wherein the coating composition includes a crosslinker.

44. The coating composition of claim 43 , wherein the crosslinker comprises a phenoplast crosslinker.

45. The coating composition of claim 1 , 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.

46. The coating composition of claim 45 , wherein the polymerizable unsaturated monomers used to generate the acid- or anhydride-functional acrylic polymer includes methacrylic acid and does not include acrylic acid.

47. The coating composition of claim 1 , wherein the amine comprises a tertiary amine.

48. The coating composition of claim 47 , wherein the tertiary amine comprises triethyl amine or dimethyl ethanol amine.

49. The coating composition of claim 1 , 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.

50. The coating composition of claim 49 , 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.

51. The coating composition of claim 49 , 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, shows no craze after the outside of the dome apex of the can is subjected to a 12 in-lbs reverse impact.

52. The coating composition of claim 51 , 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.

53. An inside spray beverage can coating composition, comprising:

an emulsion polymerized latex polymer prepared from ingredients including:

a salt of an organic-solution polymerized acid or anhydride-functional acrylic polymer and a tertiary amine;

an ethylenically unsaturated monomer component that includes an alkyl (meth)acrylate, a vinyl aromatic compound, and an oxirane-group containing monomer; and

water;

wherein the coating composition is substantially free of bound bisphenol A, and wherein the coating composition is suitable for forming an inside spray coating of a two-piece drawn and ironed aluminum beverage can.

54. The coating composition of claim 53 , wherein the oxirane-functional monomer comprises glycidyl methacrylate.

55. The coating composition of claim 53 , wherein the tertiary amine comprises triethyl amine or dimethyl ethanol amine.

56. The coating composition of claim 53 , wherein the coating composition is substantially free of bound aromatic glycidyl ether compounds.

57. The coating composition of claim 53 , wherein the coating composition includes a phenoplast crosslinker.

58. The coating composition of claim 53 , wherein the coating composition is made without using PVC compounds.

59. The coating composition of claim 53 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include methacrylic acid, styrene, and ethyl acrylate.

60. The coating composition of claim 59 , wherein the vinyl aromatic compound comprises styrene.

61. The coating composition of claim 60 , wherein the oxirane-functional monomer comprises glycidyl methacrylate.

62. The coating composition of claim 59 , wherein the ethylenically unsaturated monomer component comprises at least 20 wt-% of styrene.

63. The coating composition of claim 62 , wherein the oxirane-functional monomer comprises glycidyl methacrylate.

64. The coating composition of claim 63 , 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.

65. The coating composition of claim 59 , wherein the oxirane-functional monomer comprises glycidyl methacrylate.

66. The coating composition of claim 59 , 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.

67. The coating composition of claim 53 , wherein the vinyl aromatic compound comprises styrene.

68. The coating composition of claim 67 , wherein the oxirane-functional monomer comprises glycidyl methacrylate.

69. The coating composition of claim 53 , wherein the ethylenically unsaturated monomer component comprises at least 20 wt-% of styrene.

70. The coating composition of claim 69 , wherein the oxirane-functional monomer comprises glycidyl methacrylate.

71. The coating composition of claim 53 , 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.

72. The coating composition of claim 71 , wherein at least 10 wt-% of the salt of the organic-solution polymerized acid- or anhydride-functional acrylic polymer 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 acrylic polymer.

73. An inside spray beverage can coating composition, comprising:

an emulsion polymerized latex polymer, wherein the emulsion polymerized latex polymer is substantially free of bound bisphenol A and bound aromatic glycidyl ether compounds and is prepared from ingredients including:

a salt of an organic-solution polymerized acid- or anhydride-functional acrylic polymer and a tertiary amine,

an ethylenically unsaturated monomer component that includes an alkyl (meth)acrylate, a glycidyl ester of an alpha, beta-ethylenically unsaturated acid or anhydride, and a vinyl aromatic component that is at least 20 wt-% of the ethylenically unsaturated monomer component, and wherein the vinyl aromatic component comprises one or more aromatic compounds, and

water; and

a phenoplast crosslinker;

wherein the coating composition is substantially free of bound bisphenol A, and wherein the coating composition is suitable for forming an inside spray coating of a two-piece drawn and ironed aluminum beverage can.

74. The coating composition of claim 73 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include styrene.

75. The coating composition of claim 73 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include ethyl acrylate.

76. The coating composition of claim 73 , wherein the tertiary amine comprises triethyl amine or dimethyl ethanol amine.

77. The coating composition of claim 73 , wherein the coating composition is substantially free of bound glycidyl ether compounds.

78. The coating composition of claim 73 , wherein the coating composition is made without using PVC compounds.

79. The coating composition of claim 73 , wherein the organic-solution polymerized 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.

80. The coating composition of claim 79 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include ethyl acrylate.

81. The coating composition of claim 79 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include styrene.

82. The coating composition of claim 79 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include methacrylic acid.

83. The coating composition of claim 82 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include ethyl acrylate.

84. The coating composition of claim 79 , 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.

85. The coating composition of claim 84 , wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include ethyl acrylate.

86. The coating composition of claim 84 , wherein at least 10 wt-% of the salt of the organic-solution polymerized acid- or anhydride-functional acrylic polymer 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 acrylic polymer.

87. An inside spray beverage can coating composition, comprising:

an emulsion polymerized latex polymer, and wherein the emulsion polymerized latex polymer is prepared from ingredients including:

a salt of an organic-solution polymerized acid- or anhydride-functional acrylic polymer and a tertiary amine, wherein the polymerizable unsaturated monomers used to generate the organic-solution polymerized acid- or anhydride-functional acrylic polymer include ethyl acrylate, methacrylic acid, and styrene,

an ethylenically unsaturated monomer component that includes glycidyl methacrylate, styrene, and an alkyl (meth)acrylate, 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

water;

wherein the coating composition is substantially free of bound bisphenol A, and wherein the coating composition is suitable for forming an inside spray coating of a two-piece drawn and ironed aluminum beverage can.

88. The coating composition of claim 87 , wherein the alkyl (meth)acrylate comprises ethyl acrylate.

89. The coating composition of claim 87 , wherein the ethylenically unsaturated component comprises at least 20 wt-% styrene.

90. The coating composition of claim 87 , wherein at least 15 wt-% of the salt of the organic-solution polymerized acid- or anhydride-functional acrylic polymer 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.

91. The coating composition of claim 87 , wherein the coating composition is made without using PVC compounds.

92. The coating composition of claim 87 , wherein the coating composition is substantially free of bound aromatic glycidyl ether compounds.

93. The coating composition of claim 87 , wherein the coating composition includes a phenoplast crosslinker.

94. The coating composition of claim 93 , wherein the tertiary amine comprises triethyl amine or dimethyl ethanol amine.

95. The coating composition of claim 87 , wherein at least 40 wt-% of the ethylenically unsaturated monomer component comprises one or more monomers selected from alkyl acrylates and methacrylates.

96. The coating composition of claim 95 , wherein the alkyl (meth)acrylate comprises ethyl acrylate.

97. The coating composition of claim 95 , wherein the ethylenically unsaturated component comprises at least 20 wt-% styrene.