Flexible container coating compositions

Patent metadata

Field	Value
Publication number	US-11186744-B2
Application number	US-201916598398-A
Country	US
Kind code	B2
Filing date	Oct 10, 2019
Priority date	Nov 6, 2015
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

A coating composition includes: (a) 60 to 90 percent by weight of an active hydrogen-containing polyester having a number average molecular weight of at least 23,000, an acid value below 5 and a hydroxyl value below 10, (b) 0.1 to 10 percent by weight of a polyanhydride, and (c) 5 to 30 percent by weight of a curing agent reactive with the active hydrogens associated with (a) and (b), the percentages being based on weight of resin solids of the coating composition, where the reaction product of the coating composition forms a single coating without including a thermoplastic polymer. The coating composition is useful in coating food and beverage containers, particularly 2-piece cans formed by drawing and redrawing (DRD).

First claim

What is claimed is:

1. A coating composition comprising:
(a) 60 to 90 percent by weight of an active hydrogen-containing polyester having a number average molecular weight of at least 23,000, an acid value below 5 and a hydroxyl value below 10,
(b) 0.1 to 10 percent by weight of a polyanhydride having the following structural formula:

where m=2 to 4 and X is a divalent, trivalent or tetravalent organic group including mixed groups,
(c) 5 to 30 percent by weight of a curing agent reactive with the active hydrogens associated with (a) and (b),
the percentages being based on weight of resin solids of the coating composition, wherein the reaction product of the coating composition forms a single coating without including a thermoplastic polymer.

2. The coating composition of claim 1 in which the polyester has a number average molecular weight of at least 23,000 and up to 50,000, an acid value below 2 and a hydroxyl value below 8.

3. The coating composition of claim 1 in which X is a group of the structure:

where R 1 is C 2 to C 6 alkylene or C 2 to C 3 alkylidyne.

4. The coating composition of claim 3 in which R 1 is a mixed organic group comprising C 2 to C 6 alkylene and C 2 to C 3 alkylidyne.

5. The coating composition of claim 1 in which the curing agent is an aminoplast.

6. The coating composition of claim 1 further comprising an epoxidized polybutadiene polymer.

7. A coating composition comprising:
(i) a reaction product produced from a reaction mixture comprising:
a) a first active hydrogen-containing polyester having a number average molecular weight of at least 15,000, an acid value below 5 and a hydroxyl value below 10;
b) a second active hydrogen-containing polyester different from the first active hydrogen-containing polyester and having a number average molecular weight of at least 23,000, an acid value below 5 and a hydroxyl value below 10, wherein the first active hydrogen-containing polyester and the second active hydrogen-containing polyester together comprise 60 to 90 percent by weight;
c) 0.1 to 10 percent by weight of a polyanhydride having the following structural formula:

where m=2 to 4 and X is a divalent, trivalent or tetravalent organic group including mixed groups,
d) 5 to 30 percent by weight of a curing agent reactive with the active hydrogens associated with (a) and (b); and

(ii) an epoxidized polybutadiene polymer;
the percentages being based on weight of resin solids of the coating composition, wherein the reaction product of the coating composition forms a single coating without including a thermoplastic polymer.

8. The coating composition of claim 7 , wherein the second active hydrogen-containing polyester has an acid value of below 2.

9. A method of coating a metal can comprising:
a) applying to a planar metal substrate the coating composition of claim 1 ;
b) curing the composition on the substrate to form a coating; and
c) forming a metal can from the coated substrate.

10. The method of claim 9 in which the metal can is a seamless two-piece can.

11. The method of claim 9 in which the metal can is formed by drawing and redrawing.

12. A method of coating a metal can comprising:
a) applying to a planar metal substrate the coating composition of claim 7 ;
b) curing the composition on the substrate to form a coating; and
c) forming a metal can from the coated substrate.

13. The method of claim 12 in which the metal can is a seamless two-piece can.

14. The method of claim 12 in which the metal can is formed by drawing and redrawing.

15. A coated can comprising:
a can body; and
a single coating layer coated onto at least a portion of the can body, the coating layer comprising the reaction product of the coating composition of claim 1 .

16. A coated can comprising:
a can body; and
a single coating layer coated onto at least a portion of the can body, the coating layer comprising the reaction product of the coating composition of claim 7 .

Assignees

• Ppg Ind Ohio Inc

Inventors

• Lai Huy
• Kazik Kris M
• Veres Keri

Classifications

• B05D7/14

  to metal, e.g. car bodies (involving a chemical reaction between the metal and the coating C23) · CPC title

• B21D51/26

  cans or tins; Closing same in a permanent manner (making outlet arrangements B21D51/38; welding or soldering B23K) · CPC title

• B21D22/201

  Work-pieces; preparation of the work-pieces, e.g. lubricating, coating · CPC title

• B65D23/02

  Linings or internal coatings · CPC title

• C08G63/916 Primary

  Dicarboxylic acids and dihydroxy compounds · CPC title