Cook-in shrink film

• US 4,734,327 A
• Filed: 12/29/1986
• Issued: 03/29/1988
• Est. Priority Date: 12/29/1986
• Status: Expired due to Term

• Current Assignee: Curwood Incorporated (Amcor Plc)
• Original Assignee: Viskase Corporation (Viskase Companies Incorporated)
• Inventors: Vicik, Stephen J.
• Primary Examiner(s): Thibodeau, Paul J.
• Application Number:
  US06/946,722
• Time in Patent Office: 456 Days
• Field of Search: 428/35, 428/474.5, 428/474.7, 428/575, 428/576, 428/332
• US Class Current: 428/332
• CPC Class Codes: B32B 2307/31 Heat sealable
• CPC Class Codes: B32B 2307/7265 Non-permeable
• CPC Class Codes: B32B 2323/046 LDPE, i.e. low density polyethylene
• CPC Class Codes: B32B 2331/04 Polymers of vinyl acetate, e.g. PVA
• CPC Class Codes: B32B 2377/00 Polyamides
• CPC Class Codes: B32B 2439/70 Food packaging
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/306 comprising vinyl acetate or vinyl alcohol (co)polymers
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/34 comprising polyamides
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C08L 23/0853 Vinylacetate
• CPC Class Codes: C08L 2312/06 by radiation
• CPC Class Codes: C08L 2666/06 Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 2666/20 Macromolecular compounds having nitrogen in the main chain according to C08L75/00 - C08L79/00; Derivatives thereof
• CPC Class Codes: C08L 29/04 Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• CPC Class Codes: C08L 77/00 Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain of polyhydrazides C08L79/06; of polyamideimides or polyamide acids C08L79/08; Compositions of derivatives of such polymers
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/31725 Of polyamide
• CPC Class Codes: Y10T 428/31728 : Next to second layer of polyamide
• CPC Class Codes: Y10T 428/31909 : Next to second addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31913 : Monoolefin polymer

Abstract

An irradiated three layer heat shrinkable plastic film comprising an EVOH - Nylon core layer as an oxygen barrier, a first outer layer comprising a blend of EVA and C6-C8 olefin type LLDPE, and a second outer layer comprising EVA.

Claims

1. A three layer plastic film comprising:

(a) a core layer of between about 60 and 90 wt. % hydrolyzed ethylene-vinyl acetate copolymer containing between about 28 and 40 wt. % ethylene and blended with between about 10 and 40 wt. % amide polymer having a melting point below about 420°

F., said core layer providing an oxygen transmission rate through the film below about 90 cc/m² /mil thickness/24 hrs/Atm;

(b) a first outer layer directly adhered to one side of said core layer comprising a blend of ethylene-vinyl acetate containing between about 7 and 15 wt. % vinyl acetate and between about 10 and 25 wt. % linear low density polyethylene being a copolymer of C6 to C8 olefin and ethylene; and

(c) a second outer layer directly adhered to the other side of said core layer and comprising ethylene vinyl acetate containing between about 7 and 15 wt. % vinyl acetate;

(d) said film having been irradiated at a level of between about 1 and 5 MR.

2. A film according to claim 1 wherein the second outer layer is a blend of said ethylene vinyl acetate and up to about 10 wt. % linear low density polyethylene being a copolymer of C6 to C8 olefin and ethylene.

3. A film according to claim 1 wherein said amide polymer in the core layer is a Nylon 6 copolymer.

4. A film according to claim 3 wherein said Nylon 6 copolymer is Nylon 6, 66.

5. A film according to claim 3 wherein said Nylon 6 copolymer is Nylon 6, 12.

6. A film according to claim 1 wherein the core layer comprises between about 25 and 85 wt. % hydrolyzed ethylene-vinyl acetate copolymer blended with between about 15 and 25 wt. % amide polymer.

7. A film according to claim 1 wherein said hydrolyzed ethylene-vinyl acetate copolymer contains between about 32 and 38 wt. % ethylene.

8. A film according to claim 1 wherein hexene-1 is the C6 to C8 olefin in said first outer layer.

9. A film according to claim 1 wherein the oxygen transmission rate of said core layer is below about 75 cc/M² /mil thickness/24 hrs/Atm.

10. A film according to claim 1 wherein the total thickness of the three layers is between about 2.0 and 3.5 mils.

11. A film according to claim 10 wherein the thickness of said core layer is up to about 0.3 mils.

12. A film according to claim 1 wherein the ethylene-vinyl acetate of said first outer layer contains between about 9 and 12 wt. % vinyl acetate.

13. A film according to claim 1 wherein said first outer layer contains between about 15 and 20 wt. % linear low density polyethylene.

14. A film according to claim 2 wherein hexene-1 is the C6 to C8 olefin in said second outer layer.

15. A film according to claim 10 wherein the thickness of said first outer layer is between about 1.2 and 2.6 mils.

16. A film according to claim 1 wherein said second outer layer is a blend of said ethylene-vinyl acetate and up to about 5 wt. % linear low density polyethylene being a copolymer of hexene-1 and ethylene.

17. A film according to claim 1 wherein the ethylene vinyl acetate of said second outer layer contains between about 9 and 12 wt. % vinyl acetate.

18. A film according to claim 10 wherein the thickness of said second outer layer is between about 0.3 and 1.0 mils.

19. A film according to claim 1 which is irradiated at a level of between about 2 and 4 MR.

20. A three layer plastic film comprising:

(a) a core layer of between about 75 and 85 wt. % hydrolyzed ethylene-vinyl acetate copolymer containing between about 32 and 38 wt. % ethylene and blended with between about 15 and 25 wt. % Nylon 6,66 copolymer, said core layer having an oxygen transmission rate below about 75 cc/M² /mil thickness/24 hrs/Atm and thickness of between about 0.05 and 0.2 mils;

(b) a first outer layer of thickness between about 1.2 and 2.6 mils directly adhered to one side of said core layer comprising a blend of ethylene vinyl acetate containing between about 9 and 12 wt. % vinyl acetate, and between about 15 and 20 wt. % linear low density polyethylene being a copolymer of hexene-1 and ethylene; and

(c) a second outer layer of thickness between about 0.3 and 1.0 mils directly adhered to the other side of said core layer and comprising a blend of ethylene-vinyl acetate containing between about 9 and 12 wt. % vinyl acetate, and up to about 5 wt. % linear low density polyethylene being a copolymer of butene-1 and ethylene;

(d) said film having a total thickness of between about 2.0 and 3.5 mils and having been irradiated at a level of between about 2 and 4 MR.