Multilayer Film Having Passive and Active Oxygen Barrier Layers

Abstract

The present invention provides a multilayer film having an active oxygen barrier multilayer core comprising at least one of 1) an active oxygen barrier layer is sandwiched between two passive oxygen barrier layers, or 2) a passive oxygen barrier layer is sandwiched between two active oxygen barrier layers. In one embodiment, the active barrier layer comprises a composition that is a blend of a thermoplastic resin (A) having carbon-carbon double bonds substantially in its main chain, a transition metal salt (B), and an oxygen barrier polymer (C). In some embodiments the active barrier layer may also include a compatibilizer (D). The passive oxygen barrier layers help to maintain the oxygen barrier properties of the multilayer film after the oxygen absorbing capacity of the active barrier layer has been exhausted. As a result, the useful shelf life of the film can be extended.

That which is claimed is: 
     
         1 . A multilayer active oxygen barrier film comprising a multilayer oxygen barrier component comprising at least one of 1) an active oxygen barrier layer that is disposed between two opposing passive oxygen barrier layers, or 2) a passive oxygen barrier layer that is disposed between two opposing active oxygen barrier layers, wherein the active oxygen barrier layer comprises an oxygen scavenging composition that is a blend of:
 (A) a thermoplastic resin having carbon-carbon double bonds substantially in its main chain;   (B) a transition metal salt; and   (C) an oxygen barrier polymer,   
       wherein the passive oxygen barrier layers are selected from the group consisting of polyamide, ethylene vinyl alcohol, polyvinyl alcohol, and copolymers and combination thereof, and wherein the passive multilayer oxygen barrier component is disposed between an outer sealant layer and an outer abuse layer, and wherein the film has an oxygen scavenging rate that is at least about 0.01 cc oxygen per day per gram of the oxygen scavenging composition blend. 
     
     
         2 . The active oxygen barrier film of  claim 1 , wherein the oxygen barrier polymer (C) is selected from the group consisting of ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol, polyvinyl chloride, polyacrylonitrile, and combinations thereof. 
     
     
         3 . The active oxygen barrier film of  claim 1 , wherein the active oxygen barrier layer comprises a blend of
 (A) a thermoplastic resin that is polyoctenylene;   (B) a cobalt salt; and   (C) an oxygen barrier polymer is ethylene vinyl alcohol copolymer having an ethylene content of 30 to 44 mole %.   
     
     
         4 . The active oxygen barrier film of  claim 1 , wherein the thermoplastic resin (A) comprises at least one of the units represented by formula (I) and formula (II): 
       
         
           
           
               
               
           
         
         wherein R 1 , R 2 , R 3  and R 4  are the same or different, a hydrogen atom, a substituted or non-substituted alkyl group, a substituted or non-substituted aryl group, a substituted or non-substituted alkylaryl group, —COOR 5 , —OCOR 6 , a cyano group or a halogen atom, and R 3  and R 4  are capable of forming a ring via a methylene group or an oxymethylene group, and wherein R 5  and R 6  are a substituted or non-substituted alkyl group, a substituted or non-substituted aryl group, or a substituted or non-substituted alkylaryl group. 
       
     
     
         5 . The active oxygen barrier film of  claim 1 , wherein the thermoplastic resin (A) comprises at least one of the units represented by formula (I) and formula (II): wherein R 1 , R 2 , R 3  and R 4  are hydrogen atoms. 
     
     
         6 . The active oxygen barrier film of  claim 1 , wherein in the thermoplastic resin (A), has adjacent carbon-carbon double bonds that are separated by at least three methylenes. 
     
     
         7 . The active oxygen barrier film of  claim 1 , wherein the thermoplastic resin (A) has a unit represented by a formula (III): 
       
         
           
           
               
               
           
         
         wherein R 7  and R 8  are each independently a hydrogen atom, a substituted or non-substituted alkyl group, a substituted or non-substituted aryl group, a substituted or non-substituted alkylaryl group, —COOR 9 , —OCOR 10 , a cyano group, or a halogen atom, and R 9  and R 10  are each independently a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms. 
       
     
     
         8 . The active oxygen barrier film of  claim 1 , wherein the thermoplastic resin (A) is at least one resin selected from the group consisting of polybutadiene, polyisoprene, polychloroprene, and polyoctenylene. 
     
     
         9 . The active oxygen barrier film of  claim 6 , wherein the thermoplastic resin (A) is at least one resin selected from the group consisting of polybutadiene and polyoctenylene. 
     
     
         10 . The active oxygen barrier film of  claim 7 , wherein the thermoplastic resin (A) is polyoctenylene. 
     
     
         11 . The active oxygen barrier film of  claim 1 , wherein the transition metal salt (B) is at least one metal salt selected from the group consisting of an iron salt, a nickel salt, a copper salt, a manganese salt and a cobalt salt, and combinations thereof. 
     
     
         12 . The active oxygen barrier film of  claim 1 , wherein the oxygen absorption amount of the thermoplastic resin (A) is at least 1.6 mols per 1 mol of carbon-carbon double bonds of the thermoplastic resin (A). 
     
     
         13 . The active oxygen barrier film of  claim 1 , wherein the oxygen absorption rate of the film is at least 0.01 ml/(g·day). 
     
     
         14 . The active oxygen barrier film of  claim 1 , wherein the oxygen barrier polymer (C) has an oxygen transmission rate of 500 ml·20 μm/(m 2 ·day·atm) or less at 65% RH at 20° C. 
     
     
         15 . The active oxygen barrier film of  claim 14 , wherein the oxygen barrier polymer (C) comprises a polymer selected from the group consisting of polyvinyl alcohol, polyamide, polyvinyl chloride, polyacrylonitrile, and combinations thereof. 
     
     
         16 . The active oxygen barrier film of  claim 15 , wherein the oxygen barrier polymer (C) is an ethylene-vinyl alcohol copolymer having an ethylene content of 5 to 60 mol % and a saponification degree of about 90% or more. 
     
     
         17 . The active oxygen barrier film of  claim 15 , wherein the oxygen barrier polymer (C) is present in an amount of about 70 to 99 weight % and the thermoplastic resin (A) is present in an amount of 30 to 1 weight %, based on the combined weight of the thermoplastic resin (A) and the EVOH oxygen barrier polymer (C). 
     
     
         18 . The active oxygen barrier film of  claim 13 , further comprising a compatibilizer (D). 
     
     
         19 . The active oxygen barrier film of  claim 18 , wherein the oxygen barrier polymer (C) is present in an amount of 70 to 98.9 wt %, the thermoplastic resin (A) is present in an amount of about 1 to 29.9 weight %, and the compatibilizer (D) is present in an amount of about 0.1 to 29 weight %, based on the total weight of the thermoplastic resin (A), oxygen barrier polymer (C), and the compatibilizer (D). 
     
     
         20 . The active oxygen barrier film of  claim 1 , wherein the active oxygen barrier layer is sandwiched between opposing passive oxygen barrier layers, and wherein the passive oxygen barrier layers comprise a polyamide. 
     
     
         21 . The active oxygen barrier film of  claim 1 , wherein the passive oxygen barrier layers comprise nylon 6. 
     
     
         22 . A package comprising:
 a) a food article; and   b) a film wrapped around at least a portion of the food article, the film comprising a multilayer oxygen barrier component comprising at least one of 1) an active oxygen barrier layer that is disposed between two opposing passive oxygen barrier layers, or 2) a passive oxygen barrier layer that is disposed between two opposing active oxygen barrier layers, wherein the active oxygen layer comprises an oxygen scavenging composition that is a blend of:
 (A) a thermoplastic resin having carbon-carbon double bonds substantially in its main chain; 
 (B) a transition metal salt; and 
 (C) an oxygen barrier polymer, 
   
       wherein the passive oxygen barrier layers are polyamide, and wherein the multilayer oxygen barrier component is disposed between an outer sealant layer and an outer abuse layer, and wherein the film has an oxygen scavenging rate that is at least about 0.01 cc oxygen per day per gram of the oxygen scavenging composition blend, and a total free shrink, at 185° F., of at least 20 percent. 
     
     
         23 . A process for preparing a film having oxygen barrier properties comprising the step of coextruding a multilayer active oxygen barrier film, wherein the film comprises a multilayer oxygen barrier component comprising at least one of 1) an active oxygen barrier layer that is disposed between two opposing passive oxygen barrier layers, or 2) a passive oxygen barrier layer that is disposed between two opposing active oxygen barrier layers, wherein the active oxygen barrier layer comprises an oxygen scavenging composition that is a blend of:
 (A) a thermoplastic resin having carbon-carbon double bonds substantially in its main chain;   (B) a transition metal salt; and   (C) an oxygen barrier polymer selected from the group consisting of ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol, polyvinyl chloride, polyacrylonitrile, and combinations thereof,   
       wherein the passive oxygen barrier layers are selected from the group consisting of polyamide, ethylene vinyl alcohol, polyvinyl alcohol, and copolymers and combination thereof, and wherein the multilayer oxygen barrier component is disposed between an outer sealant layer and an outer abuse layer, and wherein the film has an oxygen scavenging rate that is at least about 0.01 cc oxygen per day per gram of the oxygen scavenging composition blend, and wherein a sealed pouch prepared from said film exhibits an oxygen ingress of 0.45% or less at 41 days storage at a temperature of 100° F. and 75% relative humidity.