Closure system

Abstract

A foil of a tagger ring foil (TRF) closure system for a container, such as a can, is provided. The foil comprises a composite of two or more layers made from different materials instead of aluminum only.

That which is claimed: 
     
         1 . A foil of a tagger ring foil (TRF) closure system for a container, such as a can, comprising a composite of two or more layers made from different materials instead of aluminum only and having a board burst strength, when measured with Australian Standard (AS) 1301.438s, of less than 400 KPa and a cross direction ring crush resistance pressure, defined as the ring crush measured using AS 1301.407s, divided by 0.152 and multiplied by the foil thickness measured using AS 1301.426s, of less than 10 MPa so that, in use, when the foil is part of a TRF closure system on a container and the foil is ruptured to gain access to the contents of the container, the ruptured foil does not form a sharp edge. 
     
     
         2 . The foil defined in  claim 1  wherein the materials that form the layers of the composite foil and the combination of the layers are selected so that the foil can be processed in a conventional container manufacturing process that includes forming the container with a TRF closure system. 
     
     
         3 . The foil defined in  claim 1  comprising a composite of the following layers: paper, a first polymer, one of a metal and a metal alloy, and a second polymer. 
     
     
         4 . The foil defined in  claim 3  wherein the paper ranges in thickness between 25 and 100 gsm. 
     
     
         5 . The foil defined in  claim 3  wherein the first polymer layer ranges in thickness of between 10 and 30 μm. 
     
     
         6 . The foil defined in  claim 3  wherein the polymer of the first polymer layer comprises a low density polyethylene co-extruded with an acrylic acid such as ethylene acrylic acid. 
     
     
         7 . The foil defined in  claim 3  wherein the metal of the metal layer comprises aluminum. 
     
     
         8 . The foil defined in  claim 3  wherein the metal layer has a thickness of between 7 and 60 μm. 
     
     
         9 . The foil defined in  claim 1  further comprising a filler for reducing the board burst or ring crush resistance pressure to a required level. 
     
     
         10 . A tagger ring foil (TRF) closure system for a container, such as a can, that comprises the composite foil defined in  claim 1 . 
     
     
         11 . A container, such as a can, that comprises the tagger ring foil (TRF) closure system defined in  claim 10 . 
     
     
         12 . The container defined in  claim 11  wherein the composite foil of the closure system is applied to the container so that a paper side of the foil is an outward facing side of the foil. 
     
     
         13 . The container defined in  claim 11  wherein the container is a metal container.