Coating compositions for packaging articles such as food and beverage containers

Patent metadata

Field	Value
Publication number	US-2016376446-A1
Application number	US-201414902501-A
Country	US
Kind code	A1
Filing date	Jul 1, 2014
Priority date	Jul 2, 2013
Publication date	Dec 29, 2016
Grant date	—

Abstract

An article, comprising a packaging article such as food or beverage container ( 20 ), or a portion thereof, that includes substrate ( 30, 32 ) and a coating ( 34 ) disposed on at least a portion of the substrate ( 30, 32 ). The coating ( 34 ) is preferably formed from a coating composition that comprises a latex emulsion having a first-stage copolymer, a second-stage copolymer, and a linkage interconnecting the first-stage copolymer and the second-stage copolymer prior to curing.

First claim

1 . An article, comprising a food or beverage container, or a portion thereof, including:
a metal substrate; and a coating disposed on at least a portion of the metal substrate, wherein the coating is formed from a coating composition having an emulsion polymerized latex that is a reaction product of a method comprising:
providing a first-stage copolymer having step-growth-functional groups;
grafting a linkage monomer to one of the of the step-growth-functional groups to provide a pendant linkage group; and
emulsion polymerizing a plurality of second-stage monomers in the presence of the first-stage copolymer to form a second-stage copolymer and to link the second-stage copolymer to the first-stage copolymer with a linkage derived from the pendant linkage group.

2 . The article of claim 1 , wherein providing the first-stage copolymer comprises emulsion polymerizing a plurality of first-stage monomers to form the first-stage copolymer.

3 . The article of claim 1 , wherein the step-growth-functional groups comprise acid-functional groups, alcohol-functional groups, amine-functional groups, or combinations thereof.

4 . The article of claim 3 , wherein the step-growth-functional groups comprise acid-functional groups, and wherein the acid-functional groups comprise carboxylic acid-functional groups, anhydrides thereof, salts thereof, or combinations thereof.

5 . The article of claim 1 , wherein the linkage monomer comprises an ethylenically-unsaturated oxirane-functional monomer.

6 . The article of claim 5 , wherein the linkage monomer comprises glycidyl acrylate, glycidyl methacrylate, or a mixture thereof.

7 . The article of claim 1 , wherein the first-stage copolymer comprises at least one structural unit produced from a polymerizable surfactant monomer.

8 - 9 . (canceled)

10 . The article of claim 1 , wherein the second-stage copolymer further comprises at least one functional group comprising an oxirane group, an isocyanate group, an azlactone group, an oxazoline group, a cyclocarbonate group, or a combination thereof.

11 . The article of claim 1 , wherein the second-stage monomers comprise one or more (meth)acrylates, one or more ethylenically-unsaturated aromatic monomers, or combinations thereof.

12 . The article of claim 1 , wherein the coating composition is substantially free of one or more of structural units derived from bisphenol A, bisphenol F, bisphenol S, any diepoxides thereof, formaldehyde or formaldehyde-forming materials, (meth)acrylamides, styrene, or combinations thereof.

13 . A method of making a coating composition that is suitable for use with food or beverage containers, the method comprising:
providing a first-stage copolymer dispersed in an aqueous carrier, the first-stage copolymer having step-growth-functional groups, reacting at least one of the step-growth-functional groups of the first-stage copolymer with a complimentary-functional group of a linkage monomer to produce a pendant ethylenically-unsaturated group; and emulsion polymerizing a plurality of ethylenically unsaturated second-stage monomers in the presence of the first-stage copolymer to produce a second-stage copolymer, wherein first-stage copolymer is linked to the second-stage copolymer.

14 . (canceled)

15 . The method of claim 13 , wherein
providing the first-stage copolymer comprises emulsion polymerizing a plurality of first-stage monomers to form the first-stage copolymer.

16 . The method of claim 13 , wherein the first-stage monomers comprise one or more polymerizable surfactant monomers.

17 . The method of claim 13 , wherein the step-growth-functional groups comprise acid-functional groups, and wherein the acid-functional groups comprise carboxylic acid-functional groups, anhydrides thereof, salts thereof, or combinations thereof, and wherein reacting the step-growth-functional group of the first-stage copolymer with the complimentary-functional group of the linkage monomer comprises conducting a condensation reaction.

18 . The method of claim 17 , further comprising neutralizing at least a portion of the acid-functional groups.

19 . The method of claim 13 , further comprising introducing a polymerization inhibitor prior to reacting the step-growth-functional group of the first-stage copolymer with the complimentary-functional group of the linkage monomer.

20 . A method of forming a coating on a food or beverage container, the method comprising:
providing a coating composition having an emulsion polymerized multi-stage latex, wherein at least a portion of the latex includes a first-stage emulsion polymerized latex copolymer linked to a second-stage emulsion polymerized copolymer, wherein a linkage formed during free-radical polymerization of the second-stage copolymer links the first-stage copolymer to the second-stage copolymer; spraying the provided coating composition onto an interior surface of the food or beverage container; and heating the sprayed coating composition to cure the coating composition, thereby providing the coating on the interior surface of the food or beverage container.

21 . The method of claim 20 , wherein the second-stage copolymer further includes a curing group, and wherein curing the coating composition comprises reacting a curing group of the second-stage copolymer with a step-growth-functional group of the first-stage copolymer.

22 . (canceled)

23 . The method of claim 20 , wherein the linkage linking the first and second copolymers includes at least one ester linkage, and is connected to the second-stage copolymer with a carbon-carbon covalent bond.

24 . The method of claim 20 , wherein the copolymer linkage has a structure selected from the group consisting of:

wherein the carbonyl groups are directly bonded to backbone carbon atoms of the first-stage copolymer and the second-stage copolymer, and wherein, optionally, each hydrogen atom of the CH 2 and CH groups is independently substituted with a C 1 -C 3 alkyl group.

25 - 54 . (canceled)

Assignees

• Valspar Sourcing Inc

Inventors

• Gibanel Sebastien
• Prouvost Benoit

Classifications

• B05D1/18

  performed by dipping · CPC title

• B32B15/08

  of synthetic resin · CPC title

• B32B15/095

  comprising polyurethanes · CPC title

• B32B15/085

  comprising polyolefins · CPC title

• B05D1/02

  performed by spraying · CPC title