Polyoxazoline curing for packaging coating compositions

Patent metadata

Field	Value
Publication number	US-10836928-B2
Application number	US-201715844047-A
Country	US
Kind code	B2
Filing date	Dec 15, 2017
Priority date	Dec 15, 2017
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

Coated packaging and methods for coating such packaging are disclosed. The coating compositions comprise a polymer comprising acid functionality and a polyoxazoline, wherein the coating composition is substantially free of formaldehyde. The coating compositions may be applied onto at least a portion of the interior and/or exterior of packaging, such as metal cans and can ends.

First claim

The invention claimed is:

1. A package coated at least in part on a surface, the coating composition comprising:
(a) a polymer comprising acid functionality, and
(b) a polyoxazoline, wherein the coating composition comprises less than 1000 ppm based on the total weight of the coating composition of formaldehyde, derivatives thereof, and residues thereof.

2. The coated package of claim 1 in which the package is a metal can.

3. The coated package of claim 1 in which the coating is applied to a food-contacting surface of the package.

4. The coated package of claim 2 in which the coating composition is applied to a can end.

5. The coated package of claim 1 in which the composition is an aqueous-based composition in which (a) and (b) are dispersed in aqueous medium.

6. The coated package of claim 1 in which the composition is an organic solvent-based composition.

7. The coated package of claim 1 in which the polymer comprising acid functionality comprises a carboxylic acid group-containing (meth)acrylic polymer.

8. The coated package of claim 1 in which the calculated molar ratio of oxazoline groups to carboxylic acid groups is from 0.03:1 to 5:1.

9. The coated package of claim 1 in which the polyoxazoline has the following structure:

wherein n is an integer of 2 to 4; R is an n-valent organic group; and each R 1 , R 2 , R 3 and R 4 are independently hydrogen or a C 1 -C 4 alkyl group.

10. The coated package of claim 9 where R 2 and R 3 are H.

11. The coated package of claim 9 in which R is a divalent radical selected from an arylene radical and an alkylene radical and n=2.

12. The coated package of claim 1 in which the polyoxazoline is a polymeric polyoxazoline.

13. The coated package of claim 12 in which the polymeric polyoxazoline comprises a polyester polyoxazoline or a (meth)acrylic polymer polyoxazoline.

14. The coated package of claim 13 in which the polyoxazoline has a number average molecular weight of 1,000-50,000.

15. A method of coating a package comprising:
(a) applying the coating composition of claim 1 to at least a portion of the package, prior to and/or after forming the package or a portion thereof; and
(b) heating the coated substrate to a temperature and for a time sufficient to cure the coating composition.

16. The method of claim 15 in which the package is a metal can.

17. The method of claim 16 in which the coating composition is applied to a food-contacting surface of the metal can.

18. The method of claim 16 in which the coating composition is applied to a can end.

19. The method of claim 15 in which the coating composition is an aqueous-based composition in which (i) and (ii) are dispersed in aqueous medium.

20. The method of claim 15 in which the polymer comprising acid functionality comprises a carboxylic acid group-containing (meth)acrylic polymer, a carboxylic acid group-containing polyester polymer, or mixtures thereof.

21. The method of claim 15 in which the calculated molar ratio of oxazoline groups to carboxylic acid groups is from 0.03:1 to 5:1.

22. The method of claim 15 in which the package is formed and the coating composition applied to at least a portion of the package.

23. The method of claim 15 in which the coating composition is applied to a planar substrate; the coating composition heated for a time and temperature sufficient to cure the coating composition; and the substrate formed into a package or a portion thereof.

24. The method of claim 23 in which the coating composition is applied continuously to a length of coil metal sheet stock.

25. The method of claim 15 in which the polyoxazoline has the following structure:

wherein n is an integer of 2 to 4; R is an n-valent organic group; R 1 , R 2 , R 3 and R 4 are independently hydrogen or a substituted or unsubstituted C 1 -C 4 alkyl group.

26. The method of claim 25 where R 2 and R 3 are H.

27. The method of claim 25 in which R is a divalent radical comprising an arylene radical or an alkylene radical and wherein n=2.

28. The method of claim 15 in which the polyoxazoline comprises a polymeric polyoxazoline.

29. The method of claim 28 in which the polymeric polyoxazoline comprises a polyester polyoxazoline or a (meth)acrylic polymer polyoxazoline.

30. The method of claim 29 in which the polyoxazoline has a number average molecular weight of 1,000-50,000.

Assignees

• Ppg Ind Ohio Inc

Inventors

• Molleo Max Aaron
• Zhou Hongying
• Seneker Carl Allen
• Kurtz Christopher Paul
• Li Qin

Classifications

• C09D133/068

  containing glycidyl groups · CPC title

• C09D133/02 Primary

  Homopolymers or copolymers of acids; Metal or ammonium salts thereof · CPC title

• C08G81/024

  Block or graft polymers containing sequences of polymers of C08C or C08F and of polymers of C08G · CPC title

• B65D1/165

  Cylindrical cans · CPC title

• C08L79/06

  Polyhydrazides; Polytriazoles; Polyamino-triazoles; Polyoxadiazoles · CPC title