Enhanced oxygen-scavenging polymers, and packaging made therefrom

Abstract

Oxygen-scavenging polymers and packaging for holding oxygen-sensitive products. A heat treatment process has been found to significantly increase the oxygen-scavenging performance of the polymer. The enhanced scavenging polymer can be effectively incorporated into various packaging, including transparent multilayer containers for beer and juice. In one embodiment, a multilayer package made from the scavenger provides an actual reduction in oxygen content of a contents of the package, over a long period of time (e.g., 24 weeks). The package can be stored unfilled for an extended period (without significant loss of scavenging capability) and will scavenge substantially immediately upon filling with a liquid product. The package may incorporate a relatively low weight percentage of the scavenger, thus providing enhanced scavenging in a cost-effective manner.

1 . A package for an aqueous liquid wherein the package has a wall comprising an oxygen-scavenging polymeric composition, a thickness of the wall adapted to achieve oxygen removal from the liquid.  
     
     
         2 . The package of  claim 1 , wherein the wall comprises a multi-layer including at least one layer of the oxygen-scavenging composition.  
     
     
         3 . The package of  claim 1 , wherein the oxygen-scavenging composition comprises a polyamide and cobalt present in an amount of at least 200 ppm in the polyamide.  
     
     
         4 . The package of  claim 3 , wherein the polyamide is a solid-stated polyamide.  
     
     
         5 . The package of  claim 4 , wherein the polyamide is MXD-6.  
     
     
         6 . The package of  claim 2 , wherein the oxygen-scavenging layer is positioned adjacent one or more layers of a polymer providing at least one of structural and oxygen barrier properties.  
     
     
         7 . The package of  claim 6 , wherein the oxygen-scavenging layer is positioned between layers of the polymer.  
     
     
         8 . The package of  claim 6 , wherein the polymer is biaxially-oriented.  
     
     
         9 . The package of  claim 8 , wherein the polymer is selected from the group consisting of polyesters and polyolefins.  
     
     
         10 . The package of  claim 9 , wherein the polymer is a polyester.  
     
     
         11 . The package of  claim 10 , wherein the polymer is polyethylene terephthalate.  
     
     
         12 . The package of  claim 6 , wherein the adjacent polymer layer is an inner layer, at least a portion of which is contacted with the aqueous liquid.  
     
     
         13 . The package of  claim 6 , wherein the package includes at least a portion having two oxygen-scavenging layers positioned between three adjacent polymer layers.  
     
     
         14 . The package of  claim 1 , wherein the aqueous liquid is beer.  
     
     
         15 . The package of  claim 1 , wherein the wall is transparent.  
     
     
         16 . The package of  claim 15 , wherein the wall has a percent haze of less than 10%.  
     
     
         17 . The package of  claim 15 , wherein the wall has a percent haze of less than 7%.  
     
     
         18 . The package of  claim 15 , wherein the wall has a percent haze of less than 5%.  
     
     
         19 . The package of  claim 2 , wherein the multi-layer has an odd number of layers.  
     
     
         20 . The package of  claim 1 , wherein the package, when filled with an aqueous liquid having a 100 ppb oxygen content, removes oxygen from the liquid.  
     
     
         21 . The package of  claim 20 , wherein after filling with the aqueous liquid the package maintains an oxygen content below 100 ppb for at least 3 months.  
     
     
         22 . A multi-layer package for enclosing an aqueous liquid having an oxygen content, the package comprising: 
 at least one oxygen-scavenging layer comprising a polyamide and cobalt in an amount of at least 200 ppm in the polyamide and wherein the package enclosing the liquid has an oxygen-removal rate greater than an oxygen-removal rate of a dry package.    
     
     
         23 . A multi-layer composition comprising: 
 an oxygen-scavenging layer comprising a polyamide and cobalt in an amount of at least 200 ppm in the polyamide; and    a structural polymer layer positioned adjacent the oxygen-scavenging layer, wherein the structural layer is permeable to water.    
     
     
         24 . A method of removing oxygen from an aqueous liquid having an oxygen content comprising: 
 providing a package having a wall comprising at least one oxygen-scavenging layer comprising a polymeric composition; and    selecting a thickness of the wall to achieve a reduction in the oxygen content.    
     
     
         25 . The method of  claim 24 , wherein the oxygen content is reduced over a period of at least 3 months.  
     
     
         26 . The method of  claim 24 , wherein the thickness selected enables reduction of an initial oxygen content of 100 ppb to a concentration of less than 50 ppb.  
     
     
         27 . The method of  claim 26 , wherein the reduction in oxygen content begins within 2 days.  
     
     
         28 . The method of  claim 24 , wherein the oxygen content is reduced at a rate of at least 50 ppb/day.  
     
     
         29 . The method of  claim 24 , wherein the oxygen content is reduced at a rate of at least 150 ppb/day.  
     
     
         30 . A method of reducing the oxygen content of a volume of a liquid comprising: 
 providing a sealed multi-layer container containing a volume of liquid, the container comprising at least one oxygen-scavenging layer, the at least one oxygen-scavenging layer comprising a polymer and cobalt, the polymer having a repeat unit including a carbonyl and at least one hydrogen atom alpha to the carbonyl, the cobalt being present in an amount of at least 200 ppm in the layer, and at least one structural polymer layer positioned between the at least one oxygen-scavenging layer and the volume of the liquid, wherein the oxygen content of the volume of the liquid in the sealed multi-layer container is maintained for a period of time below the oxygen content of a same volume of the liquid stored in a sealed glass container for the same period of time.    
     
     
         31 - 82 . (canceled)