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 enclosing an aqueous liquid, the package having a wall wherein the wall comprises at least one oxygen-scavenging layer of a solid-stated polyamide and at least 200 ppm of a transition metal in the polyamide, wherein at least a portion of the wall has a haze of less than 10%.  
     
     
         2 . The package of  claim 1 , wherein the polyamide is MXD-6.  
     
     
         3 . The package of  claim 1 , wherein the transition metal is cobalt.  
     
     
         4 . The package of  claim 1 , 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.  
     
     
         5 . The package of  claim 4 , wherein the oxygen-scavenging layer is positioned between layers of the adjacent polymer.  
     
     
         6 . The package of  claim 5 , wherein the adjacent polymer is biaxially-oriented.  
     
     
         7 . The package of  claim 6 , wherein the adjacent polymer is selected from the group consisting of a polyester and a polyolefin.  
     
     
         8 . The package of  claim 7 , wherein the adjacent polymer is a polyester.  
     
     
         9 . The package of  claim 8 , wherein the polyester is polyethylene terephthalate.  
     
     
         10 . The package of  claim 5 , wherein one adjacent polymer layer is an inner layer, at least a portion of which is contacted with the aqueous liquid.  
     
     
         11 . The package of  claim 10 , wherein the package includes at least a portion having two oxygen-scavenging layers positioned between three adjacent polymer layers.  
     
     
         12 . The package of  claim 10 , wherein the aqueous liquid is beer.  
     
     
         13 . The package of  claim 1 , wherein the at least a portion of the wall has a percent haze of less than 7%.  
     
     
         14 . The package of  claim 1 , wherein the at least a portion of the wall has a percent haze of less than 5%.  
     
     
         13 . The package of  claim 1 , wherein the at least a portion of the wall is a sidewall.  
     
     
         14 . The package of  claim 1 , wherein the entire package has a percent haze of less than 10%.  
     
     
         15 . The package of  claim 3 , wherein the oxygen-scavenging layer contains from 200 ppm to 2000 ppm of cobalt.  
     
     
         16 . The package of  claim 15 , wherein the oxygen-scavenging layer contains from 300 ppm to 1000 ppm of cobalt.  
     
     
         17 . The package of  claim 16 , wherein the oxygen-scavenging layer contains from 400 ppm to 800 ppm of cobalt.  
     
     
         18 . A container for enclosing an aqueous liquid, the container having a wall wherein the wall comprises at least one layer of a solid-stated polyamide and at least 200 ppm of cobalt in the polyamide.  
     
     
         19 . A container for enclosing an aqueous liquid, the container having a wall wherein the wall comprises at least one layer of a solid-stated polyamide, wherein at least a portion of the wall has a haze of less than 10%.  
     
     
         20 . A container for enclosing an aqueous liquid, the container having a wall wherein the wall comprises at least one layer of a polyamide and at least 200 ppm of cobalt in the polyamide, wherein at least a portion of the wall has a haze of less than 10%.