Easy-open reclosable films having an interior frangible interface and articles made therefrom

• US 20070082161A1
• Filed: 10/11/2005
• Published: 04/12/2007
• Est. Priority Date: 10/11/2005
• Status: Active Grant

• Current Assignee: Bemis Company Incorporated (Amcor Plc)
• Original Assignee: Curwood Incorporated (Amcor Plc)
• Inventors: Nelson, Kevin, Cruz, Tara
• Granted Patent: US 7,927,679 B2
• Time in Patent Office: Days
• US Class Current: 428/40.100
• CPC Class Codes: B32B 2329/04 Polyvinylalcohol
• CPC Class Codes: B32B 2367/00 Polyesters, e.g. PET, i.e. polyethylene terephthalate
• CPC Class Codes: B32B 2439/00 Containers; Receptacles closures therefor B32B2435/00
• 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 27/302 comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• 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: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/06 permitting easy separation
• CPC Class Codes: B32B 7/10 at least one layer having inter-reactive properties
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: Y10T 428/1352 Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/14 Layer or component removable to expose adhesive
• CPC Class Codes: Y10T 428/1452 Polymer derived only from ethylenically unsaturated monomer
• 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 428/2852 : Adhesive compositions
• CPC Class Codes: Y10T 428/2878 : including addition polymer from unsaturated monomer

Abstract

The present invention relates to peelable resealable multilayer films which include at least a first polymer layer, a second polymer layer of pressure-sensitive adhesive in direct contact with and bonded to both the first and third layers. The bond formed between the second and third layers includes a peelable resealable interface having a first interfacial peel strength, A, and a second interfacial peel strength, B. The peelable resealable interface includes a first interfacial peel strength, A, having a value of less than 3500 gram-force/inch (1350 newton/meter) as measured in accordance with ASTM F-904-98 test method when the films of the present invention are peeled from a second thermoplastic film to which the film has been heat-sealed. The second interfacial peel strength, B, has a value of at least 400 gram-force/inch (154 newton/meter) as measured in accordance with ASTM F-904-98 test method when the films are peeled from and re-adhered to a second film.

Claims

1. A peelable resealable multilayer film comprising:

at least a first thermoplastic layer, a second thermoplastic layer and a third thermoplastic layer;

wherein said second layer is in direct contact with and bonded to both said first and third layers;

wherein said second layer comprises a tacky pressure-sensitive adhesive;

wherein said bond between said second and third layers comprises a peelable resealable interface having a first interfacial peel strength “

A” and

a second interfacial peel strength “

B”

such that the value of A is less than 3500 gram-force/inch (1350 newton/meter) as measured in accordance with ASTM F-904 test method when peeled from a second thermoplastic film to which said film has been heat-sealed, and the value of B is at least 330 gram-force/inch (127 newton/meter) as measured in accordance with ASTM F-904 when peeled from and resealed to said second film;

and wherein the relative values of A and B satisfy the relationship A≧

B.

2. The film according to claim 1, wherein said film is coextruded by either slot cast or blown film coextrusion.

3. The film according to claim 1, wherein said first layer comprises a homopolymer or copolymer selected from the group consisting of polyolefin, ionomer and blends thereof.

4. The film according to claim 3, wherein said polyolefin comprises a homopolymer or copolymer selected from the group consisting of polyethylene, polypropylene, polybutylene and blends thereof.

5. The film according to claim 3, wherein said first layer comprises an ionomer or blend thereof.

6. The film according to claim 1, wherein said bond between said first and second layers has an interfacial peel strength of at least 3500 gram-force/inch (1350 newton/meter) as measured in accordance with ASTM F-904 test method when peeled from a second thermoplastic film to which said film has been heat-sealed.

7. The film according to claim 1, wherein said value of B is at least 400 gram-force/inch (154 newton/meter) as measured in accordance with ASTM F-904.

8. The film according to claim 1, wherein said first layer is an exterior film layer.

9. The film according to claim 1, wherein said tacky pressure sensitive adhesive comprises a tackifier first component and an elastomer second component of styrene/rubber copolymer.

10. The film according to claim 1, wherein said third layer comprises a polymer having a glass transition temperature of at least 5°

C. as measured in accordance with ASTM D-3418 test method.

11. The film according to claim 10, wherein said third layer comprises an ethylene/vinyl alcohol copolymer or blends thereof.

12. The film according to claim 10, wherein said third layer comprises polyester.

13. The film according to claim 10, wherein said third layer comprises polyamide.

14. The film according to claim 10, wherein said third layer comprises polystyrene.

15. The film according to claim 10, wherein said third layer comprises polyketone.

16. The film according to claim 10, wherein said third layer comprises acrylic ester-based polymer.

17. The film according to claim 10, wherein said third layer comprises methylpentene homopolymer or copolymer.

18. The film according to claim 10, wherein said third layer comprises cyclic olefin copolymer.

19. The film according to claim 1, wherein said film further comprises a fourth polymer layer comprising an anhydride-modified polyolefin.

20. The film according to claim 19, wherein said film further comprises a fifth polymer layer comprising a material selected from the group consisting of polyolefin, polyester, polyamide and blends thereof.

21. The film according to claim 1, wherein said film has heat shrinkage value less than about 5% in the machine direction at 90°

C. and less than about 5% in the transverse direction at 90°

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

22. A packaging article having at least one member comprising a peelable resealable multilayer film comprising:

at least a first thermoplastic layer, a second thermoplastic layer and a third thermoplastic layer;

wherein said second layer is in direct contact with and bonded to both said first and third layers;

wherein said second layer comprises a tacky pressure-sensitive adhesive;

wherein said bond between said second and third layers comprises a peelable resealable interface having a first interfacial peel strength “

A” and

a second interfacial peel strength “

B”

such that the value of A is less than 3500 gram-force/inch (1350 newton/meter) as measured in accordance with ASTM F-904 test method when peeled from a second thermoplastic film to which said film has been heat-sealed, and the value of B is at least 330 gram-force/inch (127 newton/meter) as measured in accordance with ASTM F-904 when peeled from and resealed to said second film;

and wherein the relative values of A and B satisfy the relationship A≧

B.

23. A coextruded peelable resealable multilayer film comprising:

at least a first thermoplastic layer, a second thermoplastic layer and a third thermoplastic layer;

wherein said first layer comprises a material selected from the group consisting of polyolefin, ionomer and blends thereof;

wherein said second layer is in direct contact with and bonded to both said first and third layers;

wherein said second layer comprises a tacky pressure-sensitive adhesive;

wherein said third layer comprises a material having a glass transition temperature of at least 5°

C. as measured in accordance with ASTM D-3418 test method;

wherein said bond between said second and third layers comprises a peelable resealable interface having a first interfacial peel strength “

A” and

a second interfacial peel strength “

B”

such that the value of A is less than 3500 gram-force/inch (1350 newton/meter) as measured in accordance with ASTM F-904 test method when peeled from a second thermoplastic film to which said film has been heat-sealed, and the value of B is at least 330 gram-force/inch (127 newton/meter) as measured in accordance with ASTM F-904 when peeled from and resealed to said second film;

and wherein the relative values of A and B satisfy the relationship A≧

B.

24. The film according to claim 23, wherein said film is coextruded by blown film coextrusion.

25. The film according to claim 23, wherein said polyolefin comprises a homopolymer or copolymer selected from the group consisting of polyethylene, polypropylene, polybutylene and blends thereof.

26. The film according to claim 23, wherein said first layer comprises an ionomer or blend thereof.

27. The film according to claim 23, wherein said bond between said first and second layers has an interfacial peel strength of at least 3500 gram-force/inch (1350 newton/meter) as measured in accordance with ASTM F-904 test method.

28. The film according to claim 23, wherein said value of B is at least 400 gram-force/inch (154 newton/meter) as measured in accordance with ASTM F-904.

29. The film according to claim 23, wherein said first layer is an exterior film layer.

30. The film according to claim 23, wherein said tacky pressure sensitive adhesive comprises a tackifier first component and an elastomer second component of styrene/rubber copolymer.

31. The film according to claim 23, wherein said wherein said third layer comprises a polymer selected from the group consisting of ethylene/vinyl alcohol copolymer, polyester, polyketone, polystyrene, acrylic ester-based polymer, cyclic olefin copolymer, methylpentene homopolymer or copolymer, polyamide, and blends thereof.

32. The film according to claim 31, wherein said third layer comprises an ethylene/vinyl alcohol copolymer or blend thereof.

33. The film according to claim 23, wherein said film further comprises a fourth polymer layer comprising an anhydride-modified polyolefin.

34. The film according to claim 33, wherein said film further comprises a fifth polymer layer comprising a material selected from the group consisting of polyolefin, polyester, polyamide and blends thereof.

35. The film according to claim 23, wherein said film has heat shrinkage value less than about 5% in the machine direction at 90°

C. and less than about 5% in the transverse direction at 90°

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

36. A coextruded peelable resealable multilayer thermoplastic film comprising:

a first polymer layer, a second polymer layer, a third polymer layer, a fourth polymer layer, and a fifth polymer layer;

wherein said first layer comprises a material selected from the group consisting of polyolefin, ionomer and blends thereof,

wherein said second polymer layer comprises a tacky pressure-sensitive adhesive and is in direct contact with and bonded to said first and third layers;

wherein said third layer comprises a polymer having a glass transition temperature of at least 5°

C. as measured in accordance with ASTM D-3418 and is a material selected from the group consisting of ethylene/vinyl alcohol copolymer, polyester, polyketone, polystyrene, acrylic ester-based polymer, cyclic olefin copolymer, methylpentene homopolymer or copolymer, polyamide, and blends thereof;

wherein said fourth layer comprises an anhydride-modified polyolefin and is in direct contact with and bonded to said third and fifth layers;

wherein said fifth layer comprises a material selected from the group consisting of polyolefin, polyester, polyamide and blends thereof;

wherein said bond between said second and third layers comprises a peelable resealable interface having a first interfacial peel strength “

A” and

a second interfacial peel strength “

B”

such that the value of A is less than 3500 gram-force/inch (1350 newton/meter) as measured in accordance with ASTM F-904 test method when peeled from a second thermoplastic film to which said film has been heat-sealed, and the value of B is at least 330 gram-force/inch (127 newton/meter) as measured in accordance with ASTM F-904 when peeled from and resealed to said second film;

and wherein the relative values of A and B satisfy the relationship A≧

B.

37. The film according to claim 36, wherein said film is coextruded by blown film coextrusion.

38. The film according to claim 36, wherein said polyolefin comprises a homopolymer or copolymer selected from the group consisting of polyethylene, polypropylene, polybutylene and blends thereof.

39. The film according to claim 36, wherein said first layer comprises an ionomer or blend thereof.

40. The film according to claim 36, wherein said bond between said first and second layers has an interfacial peel strength of at least 3500 gram-force/inch (1350 newton/meter) as measured in accordance with ASTM F-904 test method.

41. The film according to claim 36, wherein said value of B is at least 400 gram-force/inch (154 newton/meter) as measured in accordance with ASTM F-904

42. The film according to claim 36, wherein said first layer is an exterior film layer.

43. The film according to claim 36, wherein said tacky pressure sensitive adhesive comprises a tackifier first component and an elastomer second component of styrene/rubber copolymer.

44. The film according to claim 36, wherein said third layer comprises an ethylene/vinyl alcohol copolymer or blend thereof.

45. The film according to claim 36, wherein said film has heat shrinkage value less than about 5% in the machine direction at 90°

C. and less than about 5% in the transverse direction at 90°

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

46. A packaging article having at least one member comprising a peelable resealable multilayer film comprising a coextruded peelable resealable multilayer thermoplastic film comprising a first polymer layer, a second polymer layer, a third polymer layer, a fourth polymer layer, and a fifth polymer layer;

wherein said first layer comprises a material selected from the group consisting of polyolefin, ionomer and blends thereof;

wherein said second polymer layer comprises a tacky pressure-sensitive adhesive and is in direct contact with and bonded to said first and third layers;

wherein said third layer comprises a polymer having a glass transition temperature of at least 5°

C. as measured in accordance with ASTM D-3418 and is a material selected from the group consisting of ethylene/vinyl alcohol copolymer, polyester, polyketone, polystyrene, acrylic ester-based polymer, cyclic olefin copolymer, methylpentene homopolymer or copolymer, polyamide, and blends thereof;

wherein said fourth layer comprises an anhydride-modified polyolefin and is in direct contact with and bonded to said third and fifth layers;

wherein said fifth layer comprises a material selected from the group consisting of polyolefin, polyester, polyamide and blends thereof;

wherein said bond between said second and third layers comprises a peelable resealable interface having a first interfacial peel strength “

A” and

a second interfacial peel strength “

B”

such that the value of A is less than 3500 gram-force/inch (1350 newton/meter) as measured in accordance with ASTM F-904 test method when peeled from a second thermoplastic film to which said film has been heat-sealed, and the value of B is at least 330 gram-force/inch (127 newton/meter) as measured in accordance with ASTM F-904 when peeled from and resealed to said second film;

and wherein the relative values of A and B satisfy the relationship A≧

B.