Polyester polymer and coating compositions thereof
View Patent ↗A polymer and coating compositions containing the polymer are provided that are useful in coating applications such as, for example, food or beverage packaging coatings. The polymer preferably includes a polyester backbone and at least one deblockable isocyanate group attached to the backbone. In one embodiment, the polymer includes a polyester-carbamate backbone, one or more pendant deblockable isocyanate groups, and one or more terminal or pendant isocyanate-reactive groups. The deblockable isocyanate groups may be provided, for example, through use of a partially blocked polyisocyanate.
1. A method, comprising:
providing a coating composition comprising a polymer having a polyester backbone and one or more pendant deblockable isocyanate groups attached to the backbone; and
applying the coating composition on at least a portion of a metal substrate prior to, or after, forming the metal substrate into a food or beverage container, or a portion thereof.
2. The method of claim 1 , wherein the polymer includes terminal hydroxyl groups.
3. The method of claim 1 , wherein the polymer includes one or more terminal or pendant isocyanate-reactive groups attached to the backbone selected from amide groups, amino groups, carboxylic groups, phenol groups, thiol groups, urea groups, or combinations thereof.
4. The method of claim 1 , wherein the polymer includes a plurality of carbamate groups in the polyester backbone of the polymer.
5. The method of claim 1 , wherein the polymer comprises a reaction product of ingredients including a polyisocyanate compound having on average from about 1.5 to about to about 2.5 free isocyanate groups.
6. The method of claim 5 , wherein the polyisocyanate compound comprises an isocyanate trimer.
7. The method of claim 1 , wherein the coating composition further comprises a crosslinker.
8. The method of claim 1 , wherein the coating composition further comprises a resole phenolic crosslinker.
9. The method of claim 1 , wherein the polymer is a reaction product of ingredients comprising:
(i) a partially blocked polyisocyanate having on average from about 1.5 to about to about 2.5 free isocyanate groups, and
(ii) a hydroxyl-terminated polyester oligomer or polymer; and
wherein the ratio of free isocyanate groups in (i) to terminal hydroxyl groups in (ii) is less than 1.
10. The method of claim 1 , wherein the coating composition, based on total non-volatile weight, comprises:
from about 15 to about 70 weight percent of the polymer; and
from about 0.5 to about 30 weight percent of one or more crosslinkers.
11. The method of claim 1 , wherein the polymer includes one or more aliphatic carbon-carbon double bonds.
12. The method of claim 1 , wherein the polymer includes one or more unsaturated bicyclic groups.
13. The method of claim 1 , further comprising: after applying the coating composition on the metal substrate, forming the metal substrate into the food or beverage container, or a portion thereof.
14. The method of claim 1 , wherein the coating composition is applied onto a preformed food or beverage container or a preformed portion thereof.
15. The method of claim 1 , wherein the coating composition is a solvent-based coating composition that is substantially free of water.
16. A method, comprising:
providing a coating composition comprising:
a polymer having a polyester backbone and one or more pendant deblockable isocyanate groups attached to the backbone, and
a liquid carrier; and
applying the coating composition on at least a portion of a metal substrate prior to, or after, forming the metal substrate into a food or beverage container, or a portion thereof.
17. The method of claim 16 , wherein the coating composition is a solvent-based coating composition that is substantially free of water, and wherein the coating composition, based on total non-volatile weight, comprises: from about 15 to about 70 weight percent of the polymer; and from about 0.5 to about 30 weight percent of one or more crosslinkers.
18. The method of claim 16 , wherein the coating composition is a water-based coating composition.
19. The method of claim 18 , wherein the polymer includes one or more unsaturated bicyclic groups.
20. The method of claim 16 , wherein the coating composition includes at least 40% by weight of water based on the total weight of the coating composition, and wherein the polymer is a reaction product of ingredients comprising:
(i) a partially blocked polyisocyanate having on average from about 1.5 to about to about 2.5 free isocyanate groups, and
(ii) a hydroxyl-terminated polyester oligomer or polymer; and
wherein the ratio of free isocyanate groups in (i) to terminal hydroxyl groups in (ii) is less than 1.