Heat-sealable structure for aluminum disposable beverage-brewing containers

Abstract

The present invention relates to a heat-sealable structure comprising an aluminum foil and a heat-seal lacquer, said structure exhibiting a seal strength, according to ASTM F2824, of more than 23 N/15 mm when heat-sealed to another heat-sealable structure comprising an aluminum foil and the same heat-seal lacquer, the heat-seal lacquers of both structures contacting each other for heat sealing, said seal lacquer comprising a copolymer blend comprising: —from 30 to 80% by weight, preferably 40 to 70% by weight, more preferably from 50 to 60% by weight of a copolymer A based on (meth)acrylate ester (co)polymers, olefin (co)polymers and block or grafted copolymers comprising (met)acrylate ester sequences and olefin sequences, —from 20 to 70% by weight, preferably 30 to 60% by weight, more preferably from 40 to 50% by weight of a copolymer (B) based on vinyl halides, vinyl esters of carboxylic acids and ethylenically unsaturated (poly)carboxylic acids.

What is claimed is: 
     
         1 . A heat-sealed structure comprising:
 a first aluminum foil heat-sealed to a second aluminum foil;
 the first aluminum foil with a first heat-seal lacquer thereon representing a first heat-sealable structure, and 
 the second aluminum foil with a second heat-seal lacquer thereon, the second heat-seal lacquer being the same as the first heat-seal lacquer, the second aluminum foil with the second heat seal lacquer representing a second heat-sealable structure, 
   the first and second heat-seal lacquers of the first and second heat-sealable structures contacting each other in the heat-sealed structure,   said seal lacquer comprising a copolymer blend comprising:
 from 30 to 80% by weight, of a copolymer (A) comprising one or more (meth)acrylate ester (co)polymers, one or more olefin (co)polymers and one or more block or grafted copolymers comprising (meth)acrylate ester sequences and olefin sequences, 
 from 20 to 70% by weight of a copolymer (B) based on vinyl halides, vinyl esters of carboxylic acids and ethylenically unsaturated (poly)carboxylic acids; 
   the heat-sealed structure being characterized by a seal strength, according to ASTM F2824 of more than 23N/15 mm.   
     
     
         2 . The heat-sealed structure of  claim 1 , wherein the in that copolymer (A) and copolymer (B) are in a homogeneous distribution over an entire thickness of a seal layer between the first and second aluminum foils. 
     
     
         3 . The heat-sealed structure of  claim 1 , wherein the weight ratio of copolymer (A) to copolymer (B) is between 0.4 and 4.0. 
     
     
         4 . The heat-sealed structure according to  claim 1 , wherein each of the first and second heat-seal lacquers is characterized in that:
 copolymer (A) of the heat-seal lacquer comprises from 5 to 70% by weight of the one or more (meth)acrylate ester (co)polymers, from 5 to 70% by weight of the one or more olefin (co)polymers and from 1 to 90% by weight of the one or more block or grafted copolymers comprising (meth)acrylate ester sequences and olefin sequences;   copolymer (B) of the heat-seal lacquer comprises from 70 to 95% by weight of the one or more vinyl halide, from 1 to 30% by weight of the one or more vinyl esters of C1 to C20 carboxylic acids and from 0.1 to 10% by weight of the one or more ethylenically unsaturated (poly)carboxylic acids.   
     
     
         5 . The heat-sealed structure according to  claim 1 , characterized in that the thickness of the first and the second aluminum foils is between 20 and 160 microns and that the thickness of the heat-seal lacquers is between 1 and 20 microns. 
     
     
         6 . The heat-sealed structure according to  claim 1 , comprising one or more stoving paints or varnishes. 
     
     
         7 . The heat-sealed structure according to  claim 1 , comprising one or more printings. 
     
     
         8 . The heat-sealed structure of  claim 1 , exhibiting a seal strength, according to ASTM F2824, of more than 25 N/15 mm. 
     
     
         9 . A heat-sealed structure comprising:
 a heat-sealable structure comprising an aluminum foil and a heat-seal lacquer, that is heat-sealed to another heat-sealable structure comprising an aluminum foil and the same heat-seal lacquer, the heat-seal lacquers of both structures contacting each other for heat sealing, said seal lacquer comprising a copolymer blend comprising:   from 30 to 80% by weight of a copolymer (A) comprising one or more (meth)acrylate ester (co)polymers, one or more olefin (co)polymers and one or more block or grafted copolymers comprising (meth)acrylate ester sequences and olefin sequences,   from 20 to 70% by weight of a copolymer (B) based on vinyl halides, vinyl esters of carboxylic acids and ethylenically unsaturated (poly)carboxylic acids, wherein   copolymer (A) and copolymer (B) are homogeneously distributed over the entire thickness of the seal layer.   said heat-sealed structure exhibiting a seal strength, according to ASTM F2824, of more than 23 N/15 mm.   
     
     
         10 . The heat-sealed structure according to  claim 9  characterized in that:
 copolymer (A) of the heat-seal lacquer comprises from 5 to 70% by weight of the one or more (meth)acrylate ester (co)polymers, from 5 to 70% by weight of the one or more olefin (co)polymers and from 1 to 90% by weight of the one or more block or grafted copolymers comprising (meth)acrylate ester sequences and olefin sequences; 
 copolymer (B) of the heat-seal lacquer comprises from 70 to 95% by weight of the one or more vinyl halide, from 1 to 30% by weight of the one or more vinyl esters of C1 to C20 carboxylic acids and from 0.1 to 10% by weight of the one or more ethylenically unsaturated (poly)carboxylic acids. 
 
     
     
         11 . The heat-sealed structure according of  claim 9 , characterized in that the thickness of the aluminum foils is between 20 and 160 microns, and that the thickness of the heat-seal lacquers is between 1 and 20 microns. 
     
     
         12 . The heat-sealed structure according to  claim 9 , comprising one or more stoving paints. 
     
     
         13 . The heat-sealed structure of  claim 9 , comprising one or more varnishes. 
     
     
         14 . The heat-sealed structure according of  claim 9 , comprising one or more printings. 
     
     
         15 . The heat-sealed structure of  claim 9 , exhibiting a seal strength, according to ASTM F2824, of more than 25 N/15 mm. 
     
     
         16 . The heat-sealed structure of  claim 9 , wherein the copolymer blend comprises 40 to 70% by weight of copolymer (A). 
     
     
         17 . The heat-sealed structure of  claim 9 , wherein the copolymer blend comprises 50 to 60% by weight of copolymer (A). 
     
     
         18 . The heat-sealed structure of  claim 9 , wherein the copolymer blend comprises 30 to 60% by weight of copolymer (B). 
     
     
         19 . The heat-sealed structure of  claim 9 , wherein the copolymer blend comprises 40 to 50% by weight of copolymer (B). 
     
     
         20 . The heat-sealed structure according to  claim 9 , characterized in that the thickness of the aluminum foils is between 30 and 120 microns and that the thickness of the heat-seal lacquers is between 2 and 15 microns.