Peelable/resealable packaging film

• US 20060172131A1
• Filed: 02/01/2005
• Published: 08/03/2006
• Est. Priority Date: 02/01/2005
• Status: Active Grant

• Current Assignee: Bemis Company Incorporated (Amcor Plc)
• Original Assignee: Curwood Incorporated (Amcor Plc)
• Inventors: Nett, Lynn M., Haedt, Edward L., Sheridan, Paul J., Michels, Joseph J.
• Granted Patent: US 7,422,782 B2
• Time in Patent Office: Days
• US Class Current: 428/336
• CPC Class Codes: B32B 15/08 of synthetic resin
• CPC Class Codes: B32B 2250/03 3 layers
• CPC Class Codes: B32B 2274/00 Thermoplastic elastomer material
• CPC Class Codes: B32B 2307/31 Heat sealable
• CPC Class Codes: B32B 2307/748 Releasability
• CPC Class Codes: B32B 2439/46 Bags
• CPC Class Codes: B32B 2439/70 Food packaging
• 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 27/10 of paper or cardboard
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/06 permitting easy separation
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: Y10T 428/14 Layer or component removable to expose adhesive
• CPC Class Codes: Y10T 428/1471 Protective layer
• CPC Class Codes: Y10T 428/1476 Release layer
• CPC Class Codes: Y10T 428/1481 Dissimilar adhesives
• CPC Class Codes: Y10T 428/149 Sectional layer removable
• CPC Class Codes: Y10T 428/1495 Adhesive is on removable layer
• CPC Class Codes: Y10T 428/2495 : Thickness [relative or absolute]
• CPC Class Codes: Y10T 428/24959 : of adhesive layers
• CPC Class Codes: Y10T 428/24967 : Absolute thicknesses specified
• CPC Class Codes: Y10T 428/263 : Coating layer not in excess of 5 mils thick or equivalent
• CPC Class Codes: Y10T 428/265 : 1 mil or less
• CPC Class Codes: Y10T 428/269 : including synthetic resin or polymer layer or component
• CPC Class Codes: Y10T 428/2813 : Heat or solvent activated or sealable
• CPC Class Codes: Y10T 428/2817 : Heat sealable
• CPC Class Codes: Y10T 428/2826 : Synthetic resin or polymer
• CPC Class Codes: Y10T 428/2848 : Three or more layers
• CPC Class Codes: Y10T 428/2852 : Adhesive compositions
• CPC Class Codes: Y10T 428/2878 : including addition polymer from unsaturated monomer
• CPC Class Codes: Y10T 428/2883 : including addition polymer of diene monomer [e.g., SBR, SIS, etc.]
• CPC Class Codes: Y10T 428/31678 : Of metal
• CPC Class Codes: Y10T 428/31692 : Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31696 : Including polyene monomers [e.g., butadiene, etc.]
• CPC Class Codes: Y10T 428/31728 : Next to second layer of polyamide
• CPC Class Codes: Y10T 428/3175 : Next to addition polymer from unsaturated monomer[s]
• CPC Class Codes: Y10T 428/31786 : Of polyester [e.g., alkyd, etc.]
• CPC Class Codes: Y10T 428/31797 : Next to addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/3188 : Next to cellulosic
• CPC Class Codes: Y10T 428/31895 : Paper or wood
• CPC Class Codes: Y10T 428/31899 : Addition polymer of hydrocarbon[s] only
• CPC Class Codes: Y10T 428/31906 : Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31909 : Next to second addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31913 : Monoolefin polymer
• CPC Class Codes: Y10T 428/31917 : Next to polyene polymer
• CPC Class Codes: Y10T 428/31924 : Including polyene monomers
• CPC Class Codes: Y10T 428/31931 : Polyene monomer-containing
• CPC Class Codes: Y10T 428/31938 : Polymer of monoethylenically unsaturated hydrocarbon

Abstract

The present invention describes a multilayer film suitable for use in packaging applications comprising at least a polymeric first layer having a first surface and an opposing second surface wherein the polymeric first layer comprises a heat-sealable, water-insoluble polyester; a polymeric second layer having a first surface and an opposing second surface and comprising a pressure-sensitive adhesive, wherein the second surface of the polymeric second layer is in contact with the first surface of the polymeric first layer and forms a peelable/resealable bond therebetween; and a third layer in contact with the first surface of the polymeric second layer.

Claims

1. A multilayer film for packaging applications comprising:

(a) at least a polymeric first layer, a polymeric second layer, and a third layer;

(b) wherein said polymeric first layer is an innermost exterior-film layer, said polymeric second layer is an internal-film layer and both polymeric first and second layers are coextruded together;

(c) wherein said polymeric first layer has a first surface and an opposing second surface and comprises a heat-sealable, water-insoluble homopolymer or copolymer of polyester;

(d) wherein said polymeric second layer has a first surface and an opposing second surface and comprises a pressure-sensitive adhesive;

wherein said second surface of said polymeric second layer is in direct contact with and bonded to said first surface of said polymeric first layer such that a peelable/resealable bond is formed between said polymeric first and second layers;

wherein said first surface of said polymeric second layer is in direct contact with and bonded to said third layer; and

(e) wherein said third layer comprises a material selected from the group consisting of a thermoplastic material, a cellulosic material, a metallic material and combinations thereof.

3. A multilayer film for packaging applications according to claims 1 or 2, wherein at least said polymeric first layer and said polymeric second layer are coextruded together by either cast or blown film coextrusion.

4. A multilayer film for packaging applications according to claims 1 or 2, wherein at least said polymeric first layer, said polymeric second layer and said third layer are coextruded together by either cast of blown film coextrusion.

5. A multilayer film for packaging applications according to claims 1 or 2, wherein said heat-sealable, water-insoluble polyester comprises a material selected from the group consisting of homopolymers and copolymers of polylactic acid, polyhydroxyalkonates, polyalkyl terephthalates, polyalkyl isophthalates, polyalkyl naphthalates and blends thereof.

6. A multilayer film for packaging applications according to claims 1 or 2, wherein said pressure-sensitive adhesive comprises a tackifier first component and an elastomeric second component of a styrene/rubber block copolymer.

7. A multilayer film for packaging applications according to claims 1 or 2, wherein said pressure-sensitive adhesive comprises a styrene/rubber block copolymer selected from the group consisting of butadiene, isoprene, ethylene-butylene, ethylene-propylene, and blends thereof.

8. A multilayer film for packaging applications according to claims 1 or 2, wherein said peelable/resealable bond has an initial first peel strength of at least 2 lb/in (0.36 Kg/cm) as measured in accordance with ASTM F-904.

9. A multilayer film for packaging applications according to claims 1 or 2, wherein said peelable/resealable bond has an initial first peel strength of at least 3 lb/in (0.54 Kg/cm) as measured in accordance with ASTM F-904.

10. A multilayer film for packaging applications according to claims 1 or 2, wherein said peelable/resealable bond has a re-tack second peel strength of at least 0.50 lb/in (0.09 Kg/cm) as measured in accordance with ASTM F-904.

11. A multilayer film for packaging applications according to claims 1 or 2, wherein said peelable/resealable bond has a re-tack second peel strength of at least 0.60 lb/in (0.11 Kg/cm) as measured in accordance with ASTM F-904.

12. A multilayer film for packaging applications according to claims 1 or 2, wherein said heat-sealable, water-insoluble polyester comprises at least one material selected from the group consisting of homopolymers or copolymers of polylactic acid (PLA), polyethylene terephthalate (PET) and blends thereof.

13. A multilayer film for packaging applications according to claims 1 or 2, wherein said polymeric first layer has a thickness of between 0.05-0.5 mil (1.27-12.7 μ

m).

14. A multilayer film for packaging applications according to claims 1 or 2, wherein said polymeric first layer has a thickness of between 0.1-0.3 mil (2.54-7.62 μ

m).

15. A multilayer film for packaging applications according to claims 1 or 2, wherein said polymeric first layer is a food-contact layer.

16. A multilayer film for packaging applications according to claims 1 or 2, wherein said thermoplastic material of said third layer comprises a polyolefin, polyester, polyamide, polystyrene and blends thereof.

17. A multilayer film for packaging applications according to claims 1 or 2, wherein said metallic material comprises either a metallic foil or a metallic coating.

18. A multilayer film according to claims 1 or 2, wherein said film forms a container or a portion thereof.

2. A multilayer film for packaging applications comprising:

(a) at least a polymeric first layer, a polymeric second layer, and a third layer;

(b) wherein said polymeric first layer is an innermost exterior-film layer, said polymeric second layer is an internal-film layer and both polymeric first and second layers are coextruded together;

(c) wherein said polymeric first layer has a first surface and an opposing second surface and comprises a heat-sealable, water-insoluble homopolymer or copolymer of polyester;

(d) wherein said polymeric second layer has a first surface and an opposing second surface and comprises a pressure-sensitive adhesive;

wherein said second surface of said polymeric second layer is in direct contact with and bonded to said first surface of said polymeric first layer;

wherein said bond between said first polymeric layer and said second polymeric layer is adapted to comprise both an initial peel strength and a re-tack second peel strength;

wherein said first surface of said polymeric second layer is in direct contact with and bonded to said third layer; and

(e) wherein said third layer comprises a material selected from the group consisting of a thermoplastic material, a cellulosic material, a metallic material and combinations thereof.

19. A coextruded multilayer film for packaging applications comprising:

(a) at least a polymeric first layer, a polymeric second layer, and a polymeric third layer;

(b) wherein said polymeric first layer is an innermost exterior-film layer having a first surface and an opposing second surface and comprises a heat-sealable, water-insoluble polyester selected from the group consisting of homopolymers and copolymers of polylactic acid, polyhydroxyalkonates, polyalkyl terephthalates, polyalkyl isophthalates, polyalkyl naphthalates and blends thereof;

(c) wherein said polymeric second layer is an internal-film layer having a first surface and an opposing second surface and comprises a pressure-sensitive adhesive;

wherein said second surface of said polymeric second layer is in direct contact with said first surface of said polymeric first layer and forms a peelable/resealable bond between said polymeric first and second layers;

wherein said first surface of said polymeric second layer is in direct contact with said third layer; and

(d) wherein said third layer comprises a polyolefin.

20. A coextruded multilayer film for packaging applications according to claim 19, wherein said film is formed by either cast or blown film coextrusion.

21. A coextruded multilayer film for packaging applications according to claim 19;

wherein said pressure-sensitive adhesive comprises a tackifier first component and an elastomeric second component of a styrene/rubber block copolymer.

22. A coextruded multilayer film for packaging applications according to claim 21, wherein said styrene/rubber block copolymer comprises a material selected from the group consisting of butadiene, isoprene, ethylene-butylene, ethylene-propylene and blends thereof.

23. A coextruded multilayer film for packaging applications according to claim 19, wherein said peelable/resealable bond has an initial first peel strength of at least 2 lb/in (0.36 Kg/cm) as measured in accordance with ASTM F-904.

24. A coextruded multilayer film for packaging applications according to claim 23 wherein said peelable/resealable bond has an initial first peel strength of at least 3 lb/in (0.54 Kg/cm) as measured in accordance with ASTM F-904.

25. A coextruded multilayer film for packaging applications according to claim 19, wherein said peelable/resealable bond has a re-tack second peel strength of at least 0.50 lb/in (0.09 Kg/cm) as measured in accordance with ASTM F-904.

26. A coextruded multilayer film for packaging applications according to claim 25, wherein said peelable/resealable bond has a re-tack second peel strength of at least 0.60 lb/in (0.11 Kg/cm) as measured in accordance with ASTM F-904.

27. A coextruded multilayer film for packaging applications according to claim 19, wherein said polymeric first layer has a thickness of between 0.05-0.5 mil (1.27-12.7 μ

m).

28. A coextruded multilayer film for packaging applications according to claim 27, wherein said polymeric first layer has a thickness of between 0.1-0.3 mil (2.54-7.62 μ

m).

29. A coextruded multilayer film for packaging applications according to claim 19, wherein said polymeric first layer is a food-contact layer.

30. A coextruded multilayer film for packaging applications according to claim 19, wherein said film forms a container or a portion thereof.

31. A coextruded multilayer film for packaging applications comprising:

(a) at least a polymeric first layer, a polymeric second layer, and a polymeric third layer;

(b) wherein said polymeric first layer is an innermost exterior-film layer having a first surface and an opposing second surface and comprises a heat-sealable, water-insoluble polyester selected from the group consisting of homopolymers and copolymers of polylactic acid, polyethylene terephthalate and blends thereof;

(c) wherein said polymeric second layer is an internal-film layer having a first surface and an opposing second surface and comprises a mixture of a tackifier first component and an elastomeric second component of a styrene/rubber block copolymer;

wherein said second surface of said polymeric second layer is in direct contact with said first surface of said polymeric first layer and forms a peelable/resealable bond between said polymeric first and second layers;

wherein said first surface is in direct contact with said third layer; and

(d) wherein said third layer comprises a polyolefin.

32. A coextruded multilayer film for packaging applications according to claim 31, wherein said film is formed by either cast or blown film coextrusion.

33. A coextruded multilayer film for packaging applications according to claim 31, wherein said styrene/rubber block copolymer comprises a material selected from the group consisting of butadiene, isoprene, ethylene-butylene, ethylene-propylene and blends thereof.

34. A coextruded multilayer film for packaging applications according to claim 31, wherein said peelable/resealable bond has an initial first peel strength of at least 2 lb/in (0.36 Kg/cm) as measured in accordance with ASTM F-904.

35. A coextruded multilayer film for packaging applications according to claim 34, wherein said peelable/resealable bond has an initial first peel strength of at least 3 lb/in (0.54 Kg/cm) as measured in accordance with ASTM F-904.

36. A coextruded multilayer film for packaging applications according to claim 31, wherein said peelable/resealable bond has a re-tack second peel strength of at least 0.50 lb/in (0.09 Kg/cm) as measured in accordance with ASTM F-904.

37. A coextruded multilayer film for packaging applications according to claim 36, wherein said peelable/resealable bond has a re-tack second peel strength of at least 0.60 lb/in (0.11 Kg/cm) as measured in accordance with ASTM F-904.

38. A coextruded multilayer film for packaging applications according to claim 31, wherein said polymeric first layer has a thickness of between 0.05-0.5 mil (1.27-12.7 μ

m).

39. A coextruded multilayer film for packaging applications according to claim 38, wherein said polymeric first layer has a thickness of between 0.1-0.3 mil (2.54-7.62 μ

m).

40. A coextruded multilayer film for packaging applications according to claim 31, wherein said polymeric first layer is a food-contact layer.

41. A coextruded multilayer film for packaging applications according to claim 31, wherein said film forms a container or a portion thereof.