Container with Reduced, Peel-Off-Force Tear Configuration

Abstract

A container assembly includes a can, a can end, and a sheet which hermetically closes an access opening in the can end. The can end includes an opening for accessing the contents of the container. This opening is hermetically sealed closed by a sheet sealed to the end about the periphery of the opening with a closed-loop of adhesive. The sheet preferably includes a tab and a weakened or score line which causes the sheet to tear across the seal at an angle less than 90 degrees to the seal such that the sheet pulls away from the can end along a line generally parallel to the loop where the sheet is being separated from the can end.

What is claimed is: 
     
         1 . A container end, comprising:
 a metal rim including an inwardly extending flange with a rolled edge which defines an opening in the end, the metal rim including a thermoplastic layer and an area extending into the opening;   a foil with a thermoplastic layer, the foil covering the opening, the foil including a weakening formation and a tab formed by at least a portion of the formation;   a closed-loop seal having a central axis and formed from the layers to seal the foil to the rim such that the tab is substantially located over the area, wherein the formation is configured to promote tearing of the foil across the seal when a pulling force is initially applied to the tab and separation of the foil from the seal in a direction generally parallel to the central axis of the seal after the foil is torn across the seal; and   a seal extension extending from the closed loop between the area and the tab.   
     
     
         2 . The container end of  claim 1 , wherein the seal includes a weakened area adjacent to the weakened formation to further promote tearing of the seal across the seal. 
     
     
         3 . The container end of  claim 1 , wherein the foil is an aluminum foil and the thermoplastic layer is polypropylene. 
     
     
         4 . The container end of  claim 2 , wherein the seal is configured to prevent breach of the hermetic seal when a force of at least 20-30 pounds per square inch is applied to the portion of the foil covering the opening. 
     
     
         5 . The container end of  claim 4 , wherein the seal is further configured to prevent breach of the hermetic seal when the end is exposed to at least 220 to 250 degrees Fahrenheit. 
     
     
         6 . A metal container assembly comprising:
 a metal can end including:
 a metal rim including an inwardly extending flange which includes a rolled edge with defines an opening in the end, 
 a sheet which covers the opening such that the rolled edge is rolled toward the sheet, and 
 a closed-loop adhesive seal which hermetically seals the sheet to the flange, wherein the sheet includes a tab, and a weakening line in the vicinity of tab configured to promote tearing of the sheet across the adhesive seal; and 
   a metal can body having an open end, wherein the can end is fastened to the open end of the can by overlapping a portion of the can with a portion of the metal rim and bending the portions into a sealed joint.   
     
     
         7 . The metal container of  claim 6 , wherein the tab is oriented to be pulled in a direction generally parallel to the central axis of the adhesive seal. 
     
     
         8 . The metal container of  claim 7 , wherein the sheet is a metal foil having a thermoplastic layer. 
     
     
         9 . The metal container of  claim 8 , wherein the flange includes a thermoplastic layer and the adhesive seal is formed from a portion of the thermoplastic layers by selectively heating the overlapping layers. 
     
     
         10 . The metal container of  claim 9 , wherein the seal has a seal strength which is reduced, relative to the majority of the seal, at a weakened location along the seal, and the weakening line is located substantially at the weakened location to cause the foil to tear across the seal substantially at the weakened location. 
     
     
         11 . The container of  claim 10 , wherein the seal is formed from first and second adhesives wherein the second adhesive is weaker than the first adhesive and the second adhesive forms a portion of the seal at the weakened location. 
     
     
         12 . The container of  claim 10 , wherein the adhesive seal is formed with at least first and second cross-sections wherein the second cross-section in smaller than the first cross-section and the adhesive located at the weakened location has the second cross-section. 
     
     
         13 . The container of  claim 9 , wherein the flange has an increased area, all or a portion of the weakening line is located above the increased area, and the metal foil includes a tab at least partially defined by the weakening line. 
     
     
         14 . The container of  claim 13 , wherein the seal includes a projection located between the tab and increased area of the flange. 
     
     
         15 . A container assembly, comprising:
 a can having an open end;   a can end attached to the open end, having at least one opening defined by a periphery,   a metal foil sheet configured to close the opening; and   an adhesive which attaches the foil to the periphery of the opening to hermetically close the opening, the adhesive being configured to resist at least a force of 20-30 pounds per square inch of the portion of the foil covering the opening;   the metal foil including a weakened formation configured to promote tearing of the foil across the adhesive the foil is pulled to remove the foil from the can end.   
     
     
         16 . The container assembly of  claim 15 , the adhesive includes at least one portion which has resistance to removal of the foil which is less than the resistance to removal of at least another portion of the adhesive. 
     
     
         17 . The container assembly of  claim 16 , wherein the at least one portion has a reduced amount of adhesive. 
     
     
         18 . The container assembly of  claim 16 , wherein the can is fabricated from metal. 
     
     
         19 . The container assembly of  claim 16 , wherein the can is fabricated from a non-metallic material. 
     
     
         20 . The container assembly of  claim 15 , wherein the can end is fastened to the open end of the can by overlapping a portion of the can with a portion of the can end and bending the portions into a sealed joint. 
     
     
         21 . The container assembly of  claim 19 , wherein the sheet is integrally formed from a flexible material, and peelable from the can end. 
     
     
         22 . The container assembly of  claim 20 , wherein the flexible material is a polypropylene aluminum. 
     
     
         23 . The container of  claim 15 , wherein the foil sheet and the periphery include a thermoplastic layer, the periphery includes an increased area, and the adhesive is the combination of portions of the thermoplastic layers which are formed by selectively heating overlapping layers into a closed-loop of adhesive with a projection located at the increased area. 
     
     
         24 . A container end, comprising:
 a generally circular metal flange including an inwardly extending flange which defines an opening in the end;   a sheet which covers the opening;   an adhesive bead structure which hermetically seals the sheet to the flange, the bead structure being configured in a generally spiral form to provide concentric areas of adhesive on at least portions of the flange, the sheet being formed to permit independent removal of the sheet from the concentric areas thereby reducing the force required to separate the sheet from the opening.   
     
     
         25 . The container end of  claim 24 , wherein the sheet is a metal foil sheet which includes at least one weakening line which facilitates tearing of the foil to permit independent removal of the sheet from the concentric areas. 
     
     
         26 . The container end of  claim 25 , wherein the adhesive is a thermoplastic. 
     
     
         27 . The container end of  claim 26 , wherein the sheet is generally circular and is sealed to the can end around the perimeter of the sheet. 
     
     
         28 . The container end of  claim 27 , wherein the sheet includes a tab extending therefrom, configured to facilitate peeling of the sheet from the can end. 
     
     
         29 . A container end, comprising:
 a metal rim including an inwardly extending flange which defines an opening in the end;   a sheet which covers the opening; and   a closed-loop adhesive seal which hermetically seals the sheet to the flange, the seal, wherein the sheet includes a tab, and a weakening line in the vicinity of tab to cause the foil to tear across the seal substantially at the weakened location.   
     
     
         30 . The container end of  claim 29 , wherein the seal is formed from first and second adhesive layers located on the sheet and rim, respectively. 
     
     
         31 . The container end of  claim 30 , wherein the adhesive is a thermoplastic material. 
     
     
         32 . The container end of  claim 31 , wherein the adhesive seal is formed to have a projection extending from the closed-loop toward the tab. 
     
     
         33 . The container end of  claim 32 , wherein the weakening line crosses the adhesive loop at an angle less than 90 degrees. 
     
     
         34 . The container end of  claim 32 , wherein the flange includes a rolled edge which defines the boundary of the opening. 
     
     
         35 . The container end of  claim 34 , wherein the sheet is formed from a metal foil. 
     
     
         36 . The container end of  claim 32 , wherein the flange includes a widened location generally located below the tab and the weakened location.