Multilayer shrink films having a core layer of EVA/ionomer blend

• US 20070298273A1
• Filed: 06/27/2006
• Published: 12/27/2007
• Est. Priority Date: 06/27/2006
• Status: Abandoned Application

• Current Assignee: Clysar, LLC (Cove Point Portfolio Holdings LLC)
• Original Assignee: Bemis Clysar, Inc.
• Inventors: Thies, Robert Wayne, Idlas, Scott Allan
• Application Number:
  US11/475,762
• Publication Number:
  US 20070298273A1
• Time in Patent Office: Days
• US Class Current: 428/516
• CPC Class Codes: B32B 2250/40 Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
• CPC Class Codes: B32B 2307/736 Shrinkable
• CPC Class Codes: B32B 2553/00 Packaging equipment or accessories not otherwise provided for
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: C08L 23/0869 Acids or derivatives thereof
• CPC Class Codes: C08L 23/0876 Neutralised polymers, i.e. ionomers
• CPC Class Codes: C08L 2666/06 Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof
• CPC Class Codes: Y10T 428/2495 Thickness [relative or absolute]
• CPC Class Codes: Y10T 428/31913 Monoolefin polymer
• CPC Class Codes: Y10T 428/3192 Next to vinyl or vinylidene chloride polymer
• CPC Class Codes: Y10T 428/31935 Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31938 Polymer of monoethylenically unsaturated hydrocarbon

Abstract

Heat shrinkable multilayer packaging films comprising at least one core of a blend of at least 50% by weight of an ethylene unsaturated-ester copolymer and a material selected from the group consisting of ionomers, ethylene/acid copolymers and terpolymers, or blends, and two outer-film layers comprising a polyolefin. The invention includes films and packaging articles.

Claims

3-1. The film of claim 1, wherein said outer-film layers each comprise at least a low-density polyethylene copolymer.

19. A biaxially-oriented multilayer thermoplastic film comprising:

a) two outer-film layers each comprising a blend of a linear low-density polyethylene, a very low-density polyethylene or an ultra low-density polyethylene copolymer and a low-density polyethylene;

b) a core layer comprising a blend of at least 50% by weight relative to said core layer of a first material selected from the group consisting of ethylene vinyl acetate copolymer, ethylene butyl acetate copolymer, ethylene methyl acetate copolymer, ethylene ethyl acetate copolymer, and blends thereof, and a second material selected from the group consisting of ionomers, ethylene/acid copolymers and terpolymers, and blends thereof, and at least 20% by weight relative to said core layer of a second material selected from the group consisting of ionomers, ethylene/acid copolymers and terpolymers, and blends thereof; and

c) wherein said film has an unrestrained linear thermal shrinkage value of at least 20% in both machine and transverse directions at 100°

C. as measured in accordance with ASTM D-2732-96 test method, and a coefficient of friction of less than 0.5 as measured in accordance with ASTM D-1894 test method.

20. The film of claim 19, wherein said core layer comprises at least an acid neutralized salt of ethylene/methacrylic acid copolymer.

21. The film of claim 19, wherein said core layer has a relative thickness of between 50 to 95% of the total thickness of said film.

22. The film of claim 19, wherein said film is coextruded by a blown film coextrusion method.

23. The film of claim 19, wherein said film has a shrink tension of 300 psi or less at 100°

C. as measured in accordance with ASTM D-2838-02 test method.

24. The film of claim 19, wherein said film has a clarity value of at least 85% as measured in accordance with ASTM D-1746 test method and a haze value of less than 4% as measured in accordance with ASTM D-1003 test method.

25. The film of claim 19, wherein said film has a coefficient of friction of less than 0.25 as measured in accordance with ASTM D-1894 test method.

26. The film of claim 19, wherein said film has a coefficient of friction of less than 0.10 as measured in accordance with ASTM D-1894 test method.

27. The film of claim 19, wherein said film has an unrestrained linear thermal shrinkage value of at least 30% in the both machine and transverse directions at 100°

C. as measured in accordance with ASTM D-2732-96 test method.

28. The film of claim 19, wherein said core layer further comprises between 0.2 to 1.0% by weight of a slip agent.

29. The film of claim 19, wherein said core layer further comprises between 0.2 to 1.0% by weight of an amide slip agent.

30. The film of claim 19, wherein said film is adapted to form a packaging article.

31. A biaxially-oriented multilayer thermoplastic film comprising:

a) a first and a second outer-film layer each comprising a blend of a linear low-density polyethylene, a very low-density polyethylene or an ultra low-density polyethylene copolymer and a low-density polyethylene;

b) a core layer disposed between said first and second outer-film layers and comprising a blend of at least 50% by weight relative to said core layer of a first material selected from the group consisting of ethylene vinyl acetate copolymer, ethylene butyl acetate copolymer, ethylene methyl acetate copolymer, ethylene ethyl acetate copolymer, and blends thereof, and a second material selected from the group consisting of ionomers, ethylene/acid copolymers and terpolymers, and blends thereof, at least 20% by weight relative to said core layer of a second material selected from the group consisting of ionomers, ethylene/acid copolymers and terpolymers, and blends thereof, and between 0.2 to 1.0% by weight of an amide slip agent;

wherein said core layer has a thickness of at least 50% of the total thickness of said film;

c) a first intermediate layer positioned between said first outer-film layer and said core layer, and a second intermediate layer positioned between said second outer-film layer and said core layer;

wherein each of said intermediated layers comprise a polyolefin; and

d) wherein said film has an unrestrained linear thermal shrinkage value of at least 30% in both machine and transverse directions at 100°

C. as measured in accordance with ASTM D-2732-96 test method, and a coefficient of friction of less than 0.25 as measured in accordance with ASTM D-1894 test method.

32. The film of claim 31, wherein said film has a coefficient of friction of less than 0.10 as measured in accordance with ASTM D-1894 test method.

33. The film of claim 31, wherein said film is adapted to form a packaging article.