Heat-sealed, peelable lidding membrane for retort packaging

• US 7,798,359 B1
• Filed: 07/28/2005
• Issued: 09/21/2010
• Est. Priority Date: 08/17/2004
• Status: Active Grant

• Current Assignee: Berry Plastics Corporation (Berry Global Group Inc.)
• Original Assignee: Momar Industries, LLC
• Inventors: Marsella, Louis J.
• Primary Examiner(s): Stashick; Anthony
• Assistant Examiner(s): Hicks; Robert J
• Application Number:
  US11/191,881
• Time in Patent Office: 1,881 Days
• Field of Search: 215/13.1, 215/DIG.2, 215/305, 215/295, 220/359.4, 220/359.3, 220/359.2, 220/359.1, 220/FOR.186
• US Class Current: 220/359.3
• CPC Class Codes: B32B 15/08 of synthetic resin
• CPC Class Codes: B32B 15/20 comprising aluminium or copper B32B15/016 and B32B15/017 take precedence
• CPC Class Codes: B32B 27/06 as the main or only constituent of a layer, which is next to another layer of the same or of a different material next to a layer of a particular substance B32B9/045; next to a bituminous or tarry layer B32B11/046; next to a water setting substance layer B32B13/12; next to a metal layer B32B15/08; next to a glass layer B32B17/10; next to a layer formed of natural mineral fibres or particles B32B19/045; next to a wood layer B32B21/08; next to a cellulosic plastic layer B32B23/08; next to a natural or synthetic rubber layer B32B25/08
• 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: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: B65D 41/045 Discs B65D41/0457 takes precedence
• CPC Class Codes: B65D 53/04 Discs

Abstract

Heat-sealed, peelable lidding membrane for retort packaging. The membrane includes a plastic layer laminated to a foil layer with a first adhesive layer. A co-extruded layer is laminated to the foil layer with a second adhesive layer. The co-extruded layer is formed with a plastic body co-extruded with a heat-sealable sealing resin layer.

Claims

1. A heat-sealed, peelable lidding membrane for retort packaging comprising:

a top layer wherein said top layer prevents tearing of said membrane during removal from a container;

a foil layer laminated to said top layer with a first adhesive layer;

a co-extruded layer affixed directly to said foil layer with a second adhesive layer, said co-extruded layer having a plastic body co-extruded with a heat-sealable sealing resin layer, wherein said heat-sealable sealing resin layer is adapted to sealingly engage a container rim surrounding a container opening; and

wherein said co-extruded plastic body of said co-extruded layer has a low density polyethylene layer and a linear medium-density polyethylene layer, wherein said low density polyethylene layer is co-extruded between said co-extruded linear medium-density polyethylene layer and said co-extruded heat-sealable sealing resin layer, wherein said plastic body of said co-extruded layer prevents tearing of said co-extruded layer and causes fracture and delamination of said heat-sealable sealing resin layer from said container rim when said heat-sealed peelable lidding membrane is removed from said container rim.

2. The membrane of claim 1, wherein said top layer is a plastic layer.

3. The membrane of claim 2, wherein said plastic layer is a polyethylene terephthalate or a polyester.

4. The membrane of claim 1, wherein said first adhesive layer is a polyurethane based adhesive cured with an isocyanate based curing agent.

5. The membrane of claim 1, wherein said foil layer being aluminum foil.

6. The membrane of claim 1, wherein said second adhesive being a polyurethane based adhesive cured with an isocyanate based curing agent.

7. The membrane of claim 1, wherein said top layer being a layer of relatively stiff material.

8. The membrane of claim 7, wherein said stiff material being a paper, a cardboard, a plastic, or a composite thereof.

9. The membrane of claim 7, wherein said stiff material is a layer of talc-filled polypropylene.

10. The membrane of claim 1 including a transparent layer adhesively secured to said top layer.

11. The membrane of claim 10, wherein said top layer includes an ink layer.

32. The membrane of claim 1, wherein said first adhesive or said second adhesive is a solventless adhesive.

12. A combination of a cap and a container for retort processing of a package comprising:

a cap adapted to be received by a container neck of said container, said cap having a cap seal including a plastic layer and an elastomer layer;

said container having a heat sealed, peelable lidding membrane covering an opening in said container neck, said membrane including a top layer, a foil layer laminated to said top layer with a first adhesive layer, and a co-extruded layer affixed directly to said foil layer with a second adhesive layer, said co-extruded layer having a plastic body co-extruded with a heat sealable sealing resin layer, wherein said heat sealable sealing resin layer engages a rim surrounding said opening in said container neck; and

wherein said co-extruded plastic body of said co-extruded layer has a low density polyethylene layer and a linear medium-density polyethylene layer, wherein said low density polyethylene layer is co-extruded between said co-extruded linear medium-density polyethylene layer and said co-extruded heat-sealable sealing resin layer, wherein said co-extruded plastic body of said co-extruded layer prevents tearing of said co-extruded layer and causes fracture and delamination of said heat-sealable sealing resin layer from said rim of said container opening.

13. The combination of claim 12, wherein said top layer is a second plastic layer.

14. The combination of claim 13, wherein said second plastic layer is a polyethylene terephthalate or a polyester.

15. The combination of claim 12, wherein said first adhesive layer is a polyurethane based adhesive cured with an isocyanate based curing agent.

16. The combination of claim 12, wherein said foil layer being aluminum foil.

17. The combination of claim 12, wherein said second adhesive being a polyurethane based adhesive cured with an isocyanate based curing agent.

18. The combination of claim 12, wherein said top layer being a layer of relatively stiff material.

19. The combination of claim 18, wherein said stiff material being a paper, a cardboard, a plastic or a composite thereof.

20. The combination of claim 18, wherein said stiff material is a layer of talc-filled polypropylene.

21. The combination of claim 12, including a transparent layer adhesively secured to said top layer.

22. The combination of claim 21, wherein said top layer includes an ink layer.

23. A heat-sealed, peelable lidding membrane for retort packaging including a sealant layer structure comprising:

a top layer wherein said top layer prevents tearing of said membrane during removal from a container, a foil layer laminated to said top layer with a first adhesive layer, and a co-extruded layer affixed directly to said foil layer with a second adhesive layer;

said co-extruded layer including a plastic body and a sealant layer, said sealant layer bondable to a container lip of said container with a strength sufficient to allow said sealant layer to remain with said container when the membrane is peeled free from said container lip;

said sealant layer being capable of tearing at the periphery of said container lip when the membrane is peeled free from said container lip; and

said plastic body of said co-extruded layer has a low density polyethylene layer and a linear medium-density polyethylene layer, wherein said low density polyethylene layer is co-extruded between said co-extruded linear medium-density polyethylene layer and said co-extruded sealant layer, said plastic body co-extrusion bonded to said sealant layer with a strength sufficient to fracture said sealant layer at or near the periphery of said container lip during peeling of said complete membrane and delaminates from said sealant layer adjacent said container lip, said plastic body of said co-extruded layer having a tear resistance sufficient to achieve fracture and delamination of said sealing resin layer from said container lip.

24. The heat-sealed, peelable lidding membrane for retort packaging of claim 23 wherein said sealant layer is colored.

25. The heat-sealed, peelable lidding membrane for retort packaging of claim 23 wherein the peel force is from about 2 to 6 pounds.

26. The heat-sealed, peelable lidding membrane for retort packaging of claim 23 wherein said top layer is a polyethylene terephthalate or polyester layer.

27. The heat-sealed peelable lidding membrane for retort packaging of claim 26 wherein said polyethylene terephthalate or polyester layer includes at least one pull tab.

28. The heat-sealed, peelable lidding membrane for retort packaging of claim 23 wherein said top layer includes at least one pull tab.

29. The heat-sealed, peelable lidding membrane for retort packaging of claim 23 wherein said top layer is stiff enough for said peelable membrane to be removed without the use of a pinching grip motion.

30. The heat-sealed, peelable lidding membrane for retort packaging of claim 23 wherein said first adhesive layer or said second adhesive layer is a solventless adhesive.

31. The heat-sealed, peelable lidding membrane for retort packaging of claim 23 further comprising a secondary resilient backup structure, said secondary resilient backup structure being separate and not bonded to the rest of the peelable membrane structure, said secondary resilient backup structure may be a homogeneous material or include multiple layers coextruded or adhesive bonded together, said secondary structure may be separated from or integral with a closure and is flexible and resilient.

33. The heat-sealed, peelable lidding membrane for retort packaging of claim 23 wherein said top layer is a layer of relatively stiff material.

34. The heat-sealed, peelable lidding membrane for retort packaging of claim 33 wherein said stiff material is a paper, a cardboard, a plastic or a composite thereof.

35. The heat-sealed, peelable lidding membrane for retort packaging of claim 33 wherein said stiff material is a layer of talc-filled polypropylene.