Shrink wrap label coating to facilitate recycling

Patent metadata

Field	Value
Publication number	US-2016200942-A1
Application number	US-201414911534-A
Country	US
Kind code	A1
Filing date	Jul 24, 2014
Priority date	Aug 21, 2013
Publication date	Jul 14, 2016
Grant date	—

Abstract

The present invention discloses a method of enabling the easy separation of labels, including wrap around labels and sleeve labels, particularly shrink sleeve labels, from containers during recycling through the use of a specially formulated coating to be applied in the seam area. The coatings ensure proper bonding, and shrink properties, of the labels, and have been designed to help de-bonding of the seam in a hot caustic wash step, or a solvent wash step. The method does not rely on floatation separation and therefore may be applied to any container/label material combination regardless of their specific gravity differences.

First claim

1 . (canceled)

2 . A coating composition comprising:
a) at least one first resin with a Tg above about 25° C.; b) at least one second resin hydrolysable or solutionable in a hot caustic bath or solvent wash; and wherein the first and second resin may be the same or different.

3 . The coating composition of claim 2 , wherein the coating comprises at least one resin with a Tg above about 25° C. selected from the group consisting of polyesters, nitrocelluloses, acrylics, styrenics, including styrenic copolymers such as styrene-maleic anhydride, shellacs, epoxies, polyurethanes, and vinyls.

4 . The coating composition of claim 2 , wherein the at least one second resin which is at least partially solutioned or hydrolysed in an aqueous medium at a pH of 12 or greater.

5 . The coating composition of claim 4 , wherein the acid value of the coating composition based on dry film is greater than 20.

6 . The coating composition of claim 2 , wherein the second resin is selected from the group consisting of polyhydroxyearboxylic acids, sulfopolyesters, acrylics, polymers containing sulfonamide functionality, and polymers with a hydroxyl level of about 50 or greater.

7 . A label substrate coated with the coating composition of claim 2 .

8 . The substrate of claim 7 , wherein:
a) the coating composition produces a bond strength of coating to substrate after seaming to the substrate that is the lesser of 5 N/in or a tensile strength of the substrate; b) the coating composition produces a bond that is suitable for hot shrinking around a container or article; and c) the coating composition is delaminated when placed into a hot caustic environment, or when placed into a solvent wash.

9 . (canceled)

10 . The substrate of claim 7 , wherein the coating composition produces a bond strength of greater than 9 N/in of coating to substrate after seaming to the substrate.

11 . The substrate of claim 7 , wherein the coating composition produces a bond strength of greater than 30 N/in of coating to substrate after seaming to the substrate.

12 . The substrate of claim 7 , wherein the coating composition forms a bond with the substrate via either a solvent or heat sealing process.

13 . The substrate of claim 7 , wherein the coating composition itself functions as a seaming material, and replaces a seaming solvent.

14 . The substrate of claim 7 , which is entirely coated with the coating composition.

15 . The substrate of claim 7 , which is partially coated with the coating composition.

16 . The substrate of claim 15 , wherein at least a 7 mm margin seaming area of the substrate is coated with the coating composition.

17 . A coating system comprising:
a) a first coating layer in contact with a label substrate comprising at least one resin with a Tg above about 25° C.; and b) a second coating layer applied over the first coating layer.

18 . The coating system of claim 17 , wherein the first coating layer, the second coating layer, or both the first coating layer and the second coating layer, is further in contact with inks printed on the substrate.

19 . (canceled)

20 . (canceled)

21 . The coating system of claim 17 , wherein the coating system is at least partially hydrolysable or solutionable under conditions of recycling.

22 . The coating system of claim 17 , wherein:
a) the coating system produces a bond strength of coating to substrate after seaming to the substrate that is the lesser of 5 N/in or a tensile strength of the substrate; b) the coating system produces a bond that is suitable for hot shrinking around a container or article; and c) the coating, system is delaminated when placed into a hot caustic environment, or when placed into a solvent wash.

23 . (canceled)

24 . A method to produce a removable label for a plastic container wherein the label is removed from the container during a hot caustic wash step in the recycling process, or during a solvent wash step in the recycling process, comprising applying to the label substrate:
a) a coating composition comprising:
i. at least one first resin with a To above about 25° C.:
ii. at least one second resin hydrolysable or solutionable in a hot caustic bath or solvent wash; and
wherein the first and second resin may be the same or different; or

b) a coating system comprising:
i. a first coating layer in contact with a label substrate comprising at least one resin with a Tg above about 25° C.; and
ii. a second coating layer applied over the first coating layer.

25 . (canceled)

26 . (canceled)

27 . The method of claim 24 , wherein the label is removed by de-seaming from the container.

28 . An article wrapped with a removable sleeve label prepared according to the method of claim 24 .

29 . The article of claim 28 , wherein the label separates from the article when the article is placed into a hot caustic wash, or is placed into a solvent wash.

30 . The article of claim 28 , wherein the label separates in less than 5 minutes at 65° C.

31 . The article of claim 28 wherein the label separates in less than 3.5 minutes at 65° C.

32 . The article of claim 28 , wherein the label separates in less than 2 minutes at 75° C.

33 . The article of claim 28 , wherein the label separates in less than 1 minute at 85° C.

34 . (canceled)

35 . The article of claim 28 , wherein the label is comprised of a seamed plastic substrate.

36 . The article of claim 35 , wherein the label is a shrink label.

37 . The article of claim 28 , wherein the label is a full wrap label.

38 . The article of claim 28 , wherein the label is a partial wrap label.

39 . (canceled)

40 . (canceled)

41 . (canceled)

42 . The article of claim 28 , wherein the article is a plastic article.

Assignees

• Schottland Philippe
• Mateuszczyk Robert
• Lucci Saverio
• Zha Yongping
• Sun Chemical Corp

Inventors

• Schottland Philippe
• Mateuszczyk Robert
• Lucci Saverio
• Zha Yongping

Classifications

• B29L2031/744

  Labels, badges, e.g. marker sleeves · CPC title

• C09D129/04

  Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids · CPC title

• B29B17/02

  Separating plastics from other materials · CPC title

• B29B2017/0296

  Dissolving the materials in aqueous alkaline solutions, e.g. NaOH or KOH · CPC title

• C09D167/04

  Polyesters derived from hydroxycarboxylic acids, e.g. lactones (C09D167/06 takes precedence) · CPC title