Granted Patent B2

US 9,981,776 · App. 14/552,941 · Granted May 29, 2018

Abstract

Claims (44)

1. A method for producing a coated food or beverage can, the method comprising:

applying a coating composition onto a metal substrate, wherein the coating composition comprises:

a water-dispersible copolymer comprising:

an acrylic component having a glass transition temperature ranging from about 40° C. to about 160° C.; and

an epoxy component that is covalently attached to the acrylic component with a carbon-carbon bond;

a crosslinking agent; and

an aqueous carrier; and

curing the coating composition on the metal substrate to provide a cured coating on the metal substrate, wherein the cured coating exhibits an adhesion rating of at least 8 pursuant to the Adhesion Test after retort in a 0.4 weight percent citric acid solution pursuant to the Retort Method;

deforming at least a portion of the coated metal substrate into a can end for the coated food or beverage can such that the cured coating is located on an interior surface of the can end, and

wherein the cured coating exhibits a level of flexibility such that the cured coating located on the interior surface of the can end passes less than about 5 milliamps of electrical current pursuant to the Porosity Test prior to being subjected to any pasteurization or retort.

2. The method of claim 1 , and further comprising free-radical polymerizing monomers to produce the water-dispersible copolymer.

3. The method of claim 1 , and further comprising bonding a linking compound to an epoxy compound to produce the epoxy component, wherein the bonded linking compound is the portion of the epoxy component that is covalently attached to the acrylic component with the carbon-carbon bond.

4. The method of claim 1 , wherein the acrylic component is polymerized from a monomer mixture selected from the group consisting of an aromatic vinyl compound, acrylic acid, methacrylic acid, and combinations thereof.

5. The method of claim 1 , wherein applying the coating composition onto the metal substrate comprises coil coating the coating composition onto the metal substrate.

6. The method of claim 1 , wherein curing the coating composition on the metal substrate comprises heating the coating composition on the metal substrate to a peak metal temperature ranging from 175° C. to 280° C.

7. A method for producing a coated food or beverage can, the method comprising:

providing a cured coating on a metal substrate, wherein the cured coating is produced from a coating composition that comprises:

a water-dispersible copolymer comprising:

an acrylic component having a glass transition temperature ranging from about 40° C. to about 160° C.; and

an epoxy component that is covalently attached to the acrylic component with a carbon-carbon bond;

a crosslinking agent; and

an aqueous carrier; and

deforming at least a portion of the metal substrate into a can end of a food or beverage can, wherein the can end has an interior surface, and such that the cured coating is disposed at least on the interior surface;

wherein the cured coating on the interior surface exhibits a level of flexibility such that the cured coating passes less than about 5 milliamps of electrical current pursuant to the Porosity Test prior to being subjected to any pasteurization or retort; and

wherein the cured coating exhibits an adhesion rating of at least 8 pursuant to the Adhesion Test after retort in a 0.4 weight percent citric acid solution pursuant to the Retort Method.

8. The method of claim 7 , wherein the epoxy component comprises an epoxy-terminated group.

9. The method of claim 7 , wherein the acrylic component is polymerized from a monomer mixture selected from the group consisting of an aromatic vinyl compound, acrylic acid, methacrylic acid, and combinations thereof.

10. The method of claim 7 , wherein the cured coating composition exhibits an adhesion rating of at least 8 pursuant to the Adhesion Test after retort in a 2 weight percent citric acid solution pursuant to the Retort Method.

11. A method for producing a coated food or beverage can, the method comprising:

deforming at least a portion of the metal substrate into a can end of a food or beverage can, wherein the can end has an interior surface;

applying a coating composition on the interior surface, wherein the coating composition comprises:

a water-dispersible copolymer comprising:

an acrylic component having a glass transition temperature ranging from about 40° C. to about 160° C.; and

an epoxy component that is covalently attached to the acrylic component with a carbon-carbon bond;

a crosslinking agent; and

an aqueous carrier; and

curing the coating composition to form a cured coating on the interior surface, wherein the cured coating has:

a level of flexibility such that the cured coating passes less than about 5 milliamps of electrical current pursuant to the Porosity Test prior to being subjected to any pasteurization or retort, and

an adhesion rating of at least 8 pursuant to the Adhesion Test after retort in a 0.4 weight percent citric acid solution pursuant to the Retort Method.

12. The method of claim 11 , wherein the epoxy component comprises an epoxy-terminated group.

13. The method of claim 11 , wherein the acrylic component is polymerized from a monomer mixture selected from the group consisting of an aromatic vinyl compound, acrylic acid, methacrylic acid, and combinations thereof.

14. The method of claim 11 , wherein applying the coating composition onto the interior surface comprises spray coating the coating composition onto the interior surface.

15. The method of claim 11 , wherein curing the coating composition on the interior surface comprises heating the coating composition to a peak metal temperature ranging from 175° C. to 280° C.

16. The method of claim 11 , wherein the cured coating composition exhibits an adhesion rating of at least 8 pursuant to the Adhesion Test after retort in a 2 weight percent citric acid solution pursuant to the Retort Method.

Assignments (8)