Flexible Container Coating Compositions

Patent metadata

Field	Value
Publication number	US-2023272240-A1
Application number	US-202318311637-A
Country	US
Kind code	A1
Filing date	May 3, 2023
Priority date	Nov 6, 2015
Publication date	Aug 31, 2023
Grant date	—

Abstract

A coating composition comprising a high molecular weight polyester, a trimellitic anhydride-polyol adduct and a curing agent is disclosed. The compositions are 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 at least one 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) 0.1 to 10 percent by weight of a polyanhydride hardener comprising an active hydrogen; (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 coating composition is substantially free, essentially free, and/or completely free of bisphenol A (BPA), bisphenol A diglycidyl ether (BADGE), bisphenol F (BPF), and bisphenol F diglycidyl ether (BFDGE).

2 . The coating composition of claim 1 , wherein the polyanhydride hardener has the following structural formula:

where m=2 to 4 and X is a divalent, trivalent, or tetravalent organic group including mixed groups.

3 . The coating composition of claim 2 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 , wherein the polyanhydride hardener is prepared by reacting trimellitic anhydride with a polyol.

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

7 . The coating composition of claim 1 , wherein the at least one active hydrogen-containing polyester comprises:
a first active hydrogen-containing polyester having a number average molecular weight of at least 20,000, an acid value below 5, and a hydroxyl value below 10; and a second active hydrogen-containing polyester different from the first active hydrogen-containing polyester and having a number average molecular weight of at least 30,000, an acid value below 5, and a hydroxyl value below 10.

8 . The coating composition of claim 1 , wherein the coating composition comprises less than 5 percent by weight of the polyanhydride hardener.

9 . The coating composition of claim 6 , wherein the coating composition comprises from 0.05 to 1.0 percent by weight of the epoxidized polybutadiene polymer.

10 . The coating composition of claim 1 , wherein the polyanhydride hardener is prepared from trimellitic anhydride and wherein the curing agent is an aminoplast curing agent.

11 . A coated can, comprising:
a can body; and a coating layer coated onto at least a portion of the can body, the coating layer formed from the coating composition of claim 1 .

12 . The coated can of claim 11 , wherein the coating layer is formed over a food contact surface of the can body.

13 . The coated can of claim 11 , wherein the coating composition is applied to a planar metal sheet before the planar metal sheet is drawn to form the can body.

14 . The coated can of claim 11 , wherein the can body comprises aluminum and/or steel.

15 . The coated can of claim 11 , wherein the coated can is a two-piece can comprising a body portion and an end portion, wherein the coating layer is formed over an interior surface of the two-piece can.

16 . The coated can of claim 11 , wherein the coated can comprises a single coating layer formed over the can body.

17 . A method for preparing a metal can, comprising:
applying the coating composition of claim 1 to a planar metal sheet prior to drawing of the planar metal sheet; curing the coating composition to form a coating layer on the planar metal sheet; drawing the coated planar metal sheet into a cup; and successively re-drawing the cup into lengthened side walls to form the metal can.

18 . The method of claim 17 , wherein the planar metal sheet comprises aluminum and/or steel.

19 . The method of claim 17 , wherein the metal can comprises a two-piece can.

20 . The method of claim 17 , wherein the metal can comprises a food contact surface, wherein the coating layer is formed over at least a portion of the food contact surface.

Assignees

• Ppg Ind Ohio Inc

Inventors

• Lai Huy
• Kazik Kris M
• Veres Keri

Classifications

• C09D167/02 Primary

  Polyesters derived from dicarboxylic acids and dihydroxy compounds (C09D167/06 takes precedence) · CPC title

• C09D7/63

  organic · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• C09D167/00 Primary

  Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain (based on polyester-amides C09D177/12; based on polyester-imides C09D179/08); Coating compositions based on derivatives of such polymers · CPC title

• C08G63/916 Primary

  Dicarboxylic acids and dihydroxy compounds · CPC title