Easy-opening closure for retortable container

• US 7,055,713 B2
• Filed: 11/12/2002
• Issued: 06/06/2006
• Est. Priority Date: 11/12/2002
• Status: Expired due to Fees

• Current Assignee: Sonoco Development Inc (Sonoco Products Company)
• Original Assignee: Sonoco Development Inc (Sonoco Products Company)
• Inventors: Rea, Keith, Renck, Lawrence E.
• Primary Examiner(s): Francis, Faye
• Application Number:
  US10/292,842
• Publication Number:
  US 20040089664A1
• Time in Patent Office: 1,302 Days
• Field of Search: 220/266, 220/270, 220/276, 220/359, 220/359.3, 220/359.2
• US Class Current: 220/276
• CPC Class Codes: B65D 17/505 applied to the external and internal part of the container wall
• CPC Class Codes: B65D 2517/5013 the tape covering almost the whole of the container end panel
• CPC Class Codes: B65D 2517/5029 and connected to container by local areas of adhesive
• CPC Class Codes: B65D 2517/5048 rolled or folded back, e.g. to avoid sharp edges
• CPC Class Codes: B65D 2517/5083 with means facilitating initial lifting of tape, e.g. lift or pull-tabs

Abstract

A retortable container and an easy-opening closure for hermetic sealing of an open end thereof. The closure includes a metal end ring adapted to be double seamed to an open end of the retortable container, an intermediate area extending radially inward and defining an opening to an interior of the container, and a folded area folded into the interior of the container. The folded area extends radially outward from the opening and substantially parallel to at least an adjacent portion of the intermediate area. A first membrane patch overlaps and is bonded to an under side of the intermediate area of the end ring such that the first membrane patch prevents contamination of contents of the container by the metal end. A second membrane patch covers the opening and is bonded to an upper side of the first membrane patch. The bonds have predetermined shear and tensile force strengths sufficient to withstand shear and tensile forces created during retort processing of the container, while allowing easy-opening of the container by peeling the second membrane patch.

Claims

1. An easy-opening closure for hermetic sealing of an open end of a retortable container, the closure comprising:

a metal end ring having a deformable outside peripheral area adapted to be joined to the open end of the retortable container, an intermediate area extending radially inward from said outside peripheral area and defining an opening to allow access therethrough to the interior of the container, and a folded area folded into the interior of the container and extending radially outward from said opening and substantially parallel to and in abutting contact with said intermediate area and so as to terminate in a metal end edge;

a first membrane patch having an outside peripheral area overlapping and attached to an under side of said intermediate area of said metal end ring at a portion of the intermediate area which does not overlie the folded area by a bond having predetermined shear and tensile force strengths, and being also bonded to the folded area such as to seal the metal end edge, and having an inside peripheral area extending inwardly into said opening; and

a second membrane patch of sufficient size to cover said opening and having an outer peripheral area overlapping and attached to an upper side of said first membrane patch by a bond having predetermined shear and tensile force strengths;

wherein said predetermined shear and tensile force strengths of said bonds are sufficient to withstand shear and tensile forces created during retort processing of the container, while allowing easy-opening of the container by peeling said second membrane patch, and wherein said first membrane patch prevents contamination of contents of the container by said metal end edge.

2. An easy-opening closure according to claim 1 wherein the folded area and the adjacent portion of the metal end ring lie in parallel planes with substantially no space therebetween.

3. An easy-opening closure according to claim 1 wherein said bond between said first membrane patch and said metal end ring has a shear force strength of greater than 15 psi, and said bond between said second membrane patch and said first membrane patch has a shear force strength of greater than 15 psi and a tensile force strength of less than 5 psi.

4. An easy-opening closure according to claim 1 wherein said metal end ring comprises steel having polypropylene heat-sealable surfaces, said first membrane patch includes polypropylene heat-sealable surfaces, said second membrane patch comprises a layer having a polypropylene heat-sealable bottom surface, and said bonds comprise heat-sealed bonds.

5. An easy-opening closure according to claim 1 wherein said outer peripheral area of said second membrane patch also overlaps and is attached to an upper side of said intermediate area of said metal end ring by a bond which is unaffected during retort processing of the container and having a predetermined tensile force strength which allows peeling of said second membrane patch from said metal end ring.

6. An easy-opening closure according to claim 5 wherein said bond between said first membrane patch and said metal end ring has a shear force strength of greater than 15 psi, said bond between said second membrane patch and said first membrane patch has a shear force strength of greater than 15 psi and a tensile force strength of less than 5 psi, and said bond between said second membrane patch and said metal end ring has a tensile force strength of less than 5 psi.

7. An easy-opening closure according to claim 1 wherein said first membrane patch defines a fail portion disposed between said bonds, said fail portion being weaker than said bonds such that said first membrane patch tears at said fail portion when said second membrane patch is pulled from the closure.

8. An easy-opening closure according to claim 7 wherein said fail portion comprises a circumferentially-extending score located within said opening.

9. An easy-opening closure according to claim 1 wherein at least one of said first and second membrane patches defines an aperture that is closely adjacent said opening of said metal end ring.

23. An easy-opening closure according to claim 1 wherein said first membrane patch extends radially outwardly beyond said metal end edge such that said metal end edge is disposed between said first membrane patch and said intermediate area of said metal end ring.

10. An easy-opening closure for hermetic sealing of an open end of a retortable container, the closure comprising:

a metal end ring having a deformable outside peripheral area adapted to be double seamed to the open end of the retortable container, an intermediate area extending radially inward from said outside peripheral area and defining an opening to allow access therethrough to the interior of the container, and a folded area folded into the interior of the container against said intermediate area and extending radially outward from said opening and parallel to and in abutting contact with said intermediate area and so as to terminate in a metal end edge;

a first membrane patch having an outside peripheral area overlapping and attached to an under side of said intermediate area of said metal end ring at a portion of the intermediate area which does not overlie the folded area by a bond having predetermined shear and tensile force strengths, and being also bonded to the folded area such as to seal the metal end edge, and having an inside peripheral area extending inwardly into said opening; and

a second membrane patch of sufficient size to cover said opening and having an outer peripheral area overlapping and attached to an upper side of said first membrane patch by a bond having predetermined shear and tensile force strengths;

wherein said outer peripheral area of said second membrane patch also overlaps and is attached to an upper side of said intermediate area of said metal end ring by a bond having predetermined shear and tensile force strengths and wherein said predetermined shear and tensile force strength of said bonds are sufficient to withstand shear and tensile forces created during retort processing of the container while allowing easy-opening of the container by peeling said second membrane parch, and wherein said first membrane parch prevents contamination of contents of the container by said metal end edge.

11. An easy-opening closure according to claim 10 wherein said bond between said first membrane patch and said metal end ring has a shear force strength of greater than 15 psi, said bond between said second membrane patch and said first membrane patch has a shear force strength of greater than 15 psi and a tensile force strength of less than 5 psi, and said bond between said second membrane patch and said metal end ring has a tensile force strength of less than 5 psi.

12. An easy-opening closure according to claim 10 wherein said metal end ring comprises steel having polypropylene heat-sealable surfaces, said first membrane patch includes polypropylene heat-sealable surfaces, said second membrane patch comprises a layer having a polypropylene heat-sealable bottom surface, and said bonds comprise heat-sealed bonds.

13. An easy-opening closure according to claim 13 wherein said first membrane patch defines a fail portion disposed between said bond between said first membrane patch and said metal end ring and said bond between the first membrane patch and the second membrane patch, said fail portion being weaker than said bonds such that said first membrane patch tears at said fail portion when said second membrane patch is pulled from the closure.

14. An easy-opening closure according to claim 13 wherein said fail portion comprises a circumferentially-extending score located within said opening.

15. An easy-opening, retortable container comprising:

a base portion having a bottom and side that define an open end and an interior space and;

a metal end ring having an outside peripheral area double seamed to the open end of said base portion, an intermediate area extending radially inward from said outside peripheral area and defining an opening to allow access therethrough to the interior space, and a folded area folded into the interior space and extending radially outward from said opening and substantially parallel to and in abutting contact with said intermediate area and so as to terminate in a metal end edge;

a first membrane patch having an outside peripheral area overlapping and attached to an under side of said intermediate area of said metal end ring at a portion of the intermediate area which does not overlie the folded area by a bond having predetermined shear and tensile force strengths, and being also bonded to the folded area such as to seal the metal end edge, and having an inside peripheral area extending inwardly into said opening; and

a second membrane patch of sufficient size to cover said opening and having an outer peripheral area overlapping and attached to an upper side of said first membrane patch by a bond having predetermined shear and tensile force strengths,

wherein said predetermined shear and tensile force strength of said bonds are sufficient to withstand shear and tensile forces created during retort processing of the container, while allowing easy-opening of the container by peeling said second membrane patch, and wherein said first membrane patch prevents contamination of contents of the container by said metal end edge.

16. An easy-opening, retortable container according to claim 15 wherein said folded area and said adjacent portion of said metal end ring lie in parallel planes with substantially no space therebetween.

17. An easy-opening, retortable container according to claim 15 wherein said bond between said first membrane patch and said metal end ring has a shear force strength of greater than 15 psi, and said bond between said second membrane patch and said first membrane patch has a shear force strength of greater than 15 psi and a tensile force strength of less than 5 psi.

18. An easy-opening, retortable container according to claim 15 wherein said metal end ring comprises steel having polypropylene heat-sealable surfaces, said first membrane patch includes polypropylene heat-sealable surfaces, said second membrane patch comprises a layer having a polypropylene heat-sealable bottom surface, and said bonds comprise heat-sealed bonds.

19. An easy-opening, retortable container according to claim 15 wherein said outer peripheral area of said second membrane patch also overlaps and is attached to an upper side of said intermediate area of said metal end ring by a bond which is unaffected during retort processing of the container and having a predetermined tensile force strength which allows peeling of said second membrane patch from said metal end ring.

20. An easy-opening, retortable container according to claim 19 wherein said bond between said first membrane patch and said metal end ring has a shear force strength of greater than 15 psi, said bond between said second membrane patch and said first membrane patch has a shear force strength of greater than 15 psi and a tensile force strength of less than 5 psi, and said bond between said second membrane patch and said metal end ring has a tensile force strength of less than 5 psi.

21. An easy-opening, retortable container according to claim 15 wherein said first membrane patch defines a fall portion disposed between said bonds, said fail portion being weaker than said bonds such that said first membrane patch tears at said fail portion when said second membrane parch is pulled from the closure and wherein said fail portion comprises a circumferentially-extending score.

22. An easy-opening, retortable container according to claim 15 wherein at least one of said first and second membrane patches defines an aperture that is closely adjacent said opening of said metal end ring.

24. An easy-opening, retortable container according to claim 15 wherein said first membrane patch extends radially outwardly beyond said metal end edge such that said metal end edge is disposed between said first membrane patch and said intermediate area of said metal end ring.