Easy-open container and closure assembly therefor

Abstract

A container comprises a container body defining a top opening, a sealing surface being defined on the container body encircling the top opening, and a closure sealed to the sealing surface by a heat-seal material comprising a blend of two different acidic ionomers having respectively higher and lower acid content such that the heat-seal material has an acid content intermediate between that of the two different ionomers, whereby the resulting heat seal strikes a balance between oil-resistance and age-up.

1 . A container, comprising: 
 a container body defining a top opening, a sealing surface being defined on the container body encircling the top opening; and    a closure sealed to the sealing surface by a heat-seal material comprising a blend of first and second acidic ionomers having respectively higher and lower acid content such that the heat-seal material has an acid content intermediate between that of the first and second ionomers.    
     
     
         2 . The container of  claim 1 , further comprising a ring-shaped end member attached to the container body encircling the top opening, the sealing surface being defined by the end member.  
     
     
         3 . The container of  claim 2 , wherein the end member comprises metal.  
     
     
         4 . The container of  claim 1 , wherein the first ionomer has an acid content of about 15% by weight and the heat-seal material has an acid content of about 11% by weight.  
     
     
         5 . The container of  claim 1 , wherein the first ionomer comprises a copolymer of ethylene and methacrylic acid wherein methacrylic acid groups are partially neutralized with a cation.  
     
     
         6 . The container of  claim 1 , wherein the second ionomer comprises a copolymer of ethylene and acrylic acid wherein acrylic acid groups are partially neutralized with a cation.  
     
     
         7 . The container of  claim 1 , wherein the first ionomer comprises a copolymer of ethylene and methacrylic acid wherein methacrylic acid groups are partially neutralized with a cation and the second ionomer comprises a copolymer of ethylene and acrylic acid wherein acrylic acid groups are partially neutralized with a cation.  
     
     
         8 . The container of  claim 7 , wherein the first and second ionomers are present in approximately equal proportions by weight in the heat-seal material.  
     
     
         9 . A container, comprising: 
 a container body defining a top opening, a sealing surface being defined on the container body encircling the top opening; and    a closure sealed to the sealing surface by a heat-seal material comprising an acidic ionomer having an acid content of about 11% by weight.    
     
     
         10 . A container, comprising: 
 a container body defining a top opening;    a metal end attached to the container body encircling the top opening; and    a membrane closure sealed to the metal end by a heat-seal material comprising a blend of first and second acidic ionomers having respectively higher and lower acid content such that the heat-seal material has an acid content intermediate between that of the first and second ionomers.    
     
     
         11 . A closure assembly for a container, comprising: 
 a ring-shaped end member having a curl portion configured to be attached to a flange of a container by double-seaming, the end member further comprising a portion located radially inwardly from the curl portion and defining a sealing surface; and    a flexible membrane closure configured to attach to the ring-shaped end member;    wherein each of the end member and the closure has a heat-seal material disposed thereon for attaching the closure to the end member by heat-sealing, the heat-seal material comprising a blend of first and second acidic ionomers having respectively higher and lower acid content such that the heat-seal material has an acid content intermediate between that of the first and second ionomers.    
     
     
         12 . The closure assembly of  claim 11 , wherein the first ionomer has an acid content of about 15% by weight and the heat-seal material has an acid content of about 11% by weight.  
     
     
         13 . The closure assembly of  claim 11 , wherein the first ionomer comprises a copolymer of ethylene and methacrylic acid wherein methacrylic acid groups are partially neutralized with a cation.  
     
     
         14 . The closure assembly of  claim 11 , wherein the second ionomer comprises a copolymer of ethylene and acrylic acid wherein acrylic acid groups are partially neutralized with a cation.  
     
     
         15 . The closure assembly of  claim 11 , wherein the first ionomer comprises a copolymer of ethylene and methacrylic acid wherein methacrylic acid groups are partially neutralized with a cation and the second ionomer comprises a copolymer of ethylene and acrylic acid wherein acrylic acid groups are partially neutralized with a cation.  
     
     
         16 . A member for a closure assembly of a container, comprising: 
 a ring-shaped end member having a curl portion configured to be attached to a flange of a container by double-seaming, the end member further comprising a portion located radially inwardly from the curl portion and defining a sealing surface, and a heat-seal material disposed on the sealing surface for attaching a membrane closure to the end member by heat-sealing, the heat-seal material comprising a blend of first and second acidic ionomers having respectively higher and lower acid content such that the heat-seal material has an acid content intermediate between that of the first and second ionomers.    
     
     
         17 . The member of  claim 16 , wherein the first ionomer has an acid content of about 15% by weight and the heat-seal material has an acid content of about 11% by weight.  
     
     
         18 . The member of  claim 16 , wherein the first ionomer comprises a copolymer of ethylene and methacrylic acid wherein methacrylic acid groups are partially neutralized with a cation.  
     
     
         19 . The member of  claim 16 , wherein the second ionomer comprises a copolymer of ethylene and acrylic acid wherein acrylic acid groups are partially neutralized with a cation.  
     
     
         20 . The member of  claim 16 , wherein the first ionomer comprises a copolymer of ethylene and methacrylic acid wherein methacrylic acid groups are partially neutralized with a cation and the second ionomer comprises a copolymer of ethylene and acrylic acid wherein acrylic acid groups are partially neutralized with a cation.  
     
     
         21 . A flexible membrane closure for a container, comprising: 
 at least one structural layer of flexible material; and    a heat-seal material joined to the at least one structural layer and exposed at one surface of the closure for heat-sealing to a sealing surface provided on a container, the heat-seal material comprising a blend of first and second acidic ionomers having respectively higher and lower acid content such that the heat-seal material has an acid content intermediate between that of the first and second ionomers.    
     
     
         22 . The flexible membrane closure of  claim 21 , wherein the first ionomer has an acid content of about 15% by weight and the heat-seal material has an acid content of about 11% by weight.  
     
     
         23 . The flexible membrane closure of  claim 21 , wherein the first ionomer comprises a copolymer of ethylene and methacrylic acid wherein methacrylic acid groups are partially neutralized with a cation.  
     
     
         24 . The flexible membrane closure of  claim 21 , wherein the second ionomer comprises a copolymer of ethylene and acrylic acid wherein acrylic acid groups are partially neutralized with a cation.  
     
     
         25 . The flexible membrane closure of  claim 21 , wherein the first ionomer comprises a copolymer of ethylene and methacrylic acid wherein methacrylic acid groups are partially neutralized with a cation and the second ionomer comprises a copolymer of ethylene and acrylic acid wherein acrylic acid groups are partially neutralized with a cation.