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 comprising a composite of two or more layers made from different materials, wherein at least one layer comprises aluminium, 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, an aluminium layer comprising one of an aluminium and an aluminium 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. 
     
     
         7 . The foil defined in  claim 3  wherein the aluminium layer has a thickness of between 7 and 60 μm. 
     
     
         8 . The foil defined in  claim 1  further comprising a filler for reducing the board burst strength or the ring crush resistance pressure to a required level. 
     
     
         9 . A tagger ring foil (TRF) closure system for a container that comprises the composite foil defined in  claim 1 . 
     
     
         10 . A container that comprises the tagger ring foil (TRF) closure system defined in  claim 9 . 
     
     
         11 . The container defined in  claim 10  wherein the composite foil of the closure system comprises a paper side and is applied to the container so that the paper side of the foil is an outward facing side of the foil. 
     
     
         12 . The container defined in  claim 10  wherein the container is a metal container.