Tamper Evidencing Metal Foil Container Closure

Abstract

A tamper evident metal foil closure for a container which provides visual evidence of tampering in the form of damage to the metal foil (e.g. tearing) and evidence of temperature tampering of the metal foil when heat is used to remove and reseal the metal foil. Containers sealed with this novel metal foil closure make it more difficult to tamper with or remove the container contents and then return the container for a refund.

What is claimed is: 
     
         1 . A tamper evidencing closure for a container comprising:
 a metal ring;   a metal foil sealed to the ring on one side of the metal foil with a thermoplastic adhesive; and   a heat-sensitive, color-changing ink applied to one of the ring or the metal foil adjacent to the adhesive wherein the temperature at which the ink changes color is above ambient air temperature and below the melting point of the adhesive.   
     
     
         2 . The closure of  claim 1 , wherein the ring includes a double seam flange adjacent to an interior flange which defines an opening and the metal foil is adhered to the interior flange to span and seal close the opening. 
     
     
         3 . The closure of  claim 2 , wherein the metal foil includes a weakening formation adjacent to the interior flange. 
     
     
         4 . The closure of  claim 3 , wherein the closure further includes a pull-tab joined to the metal foil generally adjacent to the weakening formation. 
     
     
         5 . The closure of  claim 4 , wherein the weakening formation is a groove extending adjacent to the edge of the interior flange. 
     
     
         6 . The closure of  claim 1 , wherein the ink changes color at temperatures above 150 to 160 degrees F. 
     
     
         7 . The closure of  claim 6 , wherein the melting point of the adhesive is from 180 to 190 degrees F. 
     
     
         8 . The closure of  claim 2 , wherein the double seam flange has a top side and a bottom side which engages a respective container and the interior flange has a top surface which extends from the topside and a bottom surface which extends from the bottom side, the metal foil being adhered to the topside. 
     
     
         9 . The closure of  claim 2 , wherein the double seam flange has a top side and a bottom side which engages a respective container and the interior flange has a top surface which extends from the topside and a bottom surface which extends from the bottom side, the metal foil being adhered to the bottom side. 
     
     
         10 . A food container comprising:
 a cylindrical container body defined by a base from which a cylindrical wall extends to a top edge;   a metal foil;   a thermoplastic adhesive;   a metal ring including a double seam flange adjacent to an interior flange which defines an opening, the metal foil being adhered to the interior flange with the thermoplastic adhesive to span and seal close the opening; and   a heat-sensitive, color-changing ink applied adjacent to the adhesive and on an exterior surface of the container defined by of one of the metal ring or foil, wherein the temperature at which the ink changes color is above ambient air temperature and below the melting point of the adhesive, wherein the double seam flange is rolled into a seal with the cylindrical container at the top edge such that the container, the seal, the metal ring, the adhesive and the metal foil are joined to form a hermetically sealed enclosure having a predetermined volume.   
     
     
         11 . The closure of  claim 10 , wherein the metal foil includes a weakening formation adjacent to the interior flange. 
     
     
         12 . The closure of  claim 11 , wherein the closure further includes a pull-tab joined to the metal foil generally adjacent to the weakening formation. 
     
     
         13 . The closure of  claim 12 , wherein the weakening formation is a groove extending adjacent to the edge of the interior flange. 
     
     
         14 . The closure of  claim 10 , wherein the ink changes color at temperatures above 150 to 160 degrees F. 
     
     
         15 . The closure of  claim 14 , wherein the melting point of the adhesive is from 180 to 190 degrees F. 
     
     
         16 . The closure of  claim 10 , wherein the double seam flange has a top side and a bottom side which engages the top edge and the interior flange has a top surface which extends from the topside and a bottom surface which extends from the bottom side, the metal foil being adhered to the topside. 
     
     
         17 . The closure of  claim 10 , wherein the double seam flange has a top side and a bottom side which engages the top edge and the interior flange has a top surface which extends from the topside and a bottom surface which extends from the bottom side, the metal foil being adhered to the bottom side. 
     
     
         18 . A food container comprising:
 a cylindrical container body defined by a body from which a cylindrical wall extends to a top edge;   a metal ring including a double seam flange adjacent to an interior flange which defines an opening, wherein the double seam flange has a top side and a bottom side and the interior flange has a top surface which extends from the topside and a bottom surface which extends from the bottom side; and   a metal foil which spans the bottom side, the bottom surface and the opening to cover the opening; wherein the double seam flange and the top edge are formed into a seam having the metal foil captured between the double seam flange an the top edge of the container.   
     
     
         19 . The food container of  claim 18  further comprising a thermoplastic adhesive which bonds the metal foil to the metal ring. 
     
     
         20 . The food container of  claim 18 , wherein the metal foil includes a weakening formation adjacent to the interior flange and a pull-tab joined to the metal foil adjacent to the formation.