Enhanced oxygen barrier performance from modification of ethylene vinyl alcohol copolymers (EVOH)

Abstract

Herein is disclosed a modified ethylene vinyl alcohol polymer (EVOH) comprising an oxygen scavenging functional group. Preferably, the modified EVOH comprises structures IV, V, and VI: wherein x is an integer greater than or equal to 1, y is an integer greater than or equal to 1, z is an integer greater than or equal to 1, and R comprises a cycloalkenyl group. The modified EVOH is useful in oxygen barrier applications, such as a forming an oxygen barrier layer of a packaging article. Also disclosed are methods of modifying ethylene vinyl alcohol polymers, and using the modified EVOH to make packaging articles with a superior barrier to entry by atmospheric oxygen.

What is claimed is:  
     
         1 . An oxygen barrier composition, comprising a modified ethylene vinyl alcohol polymer (EVOH) comprising an oxygen scavenging functional group.  
     
     
         2 . The oxygen barrier composition of  claim 1 , wherein the modified EVOH comprises structures IV, V, and VI:  
       
         
           
           
               
               
           
         
         wherein x is an integer greater than or equal to 1, y is an integer greater than or equal to 1, z is an integer greater than or equal to 1, and R comprises a cycloalkenyl group.  
       
     
     
         3 . The oxygen barrier composition of  claim 2 , wherein R has structure II:  
       
         
           
           
               
               
           
         
         wherein q 1 , q 2 , q 3 , q 4 , and r are independently selected from hydrogen, methyl, or ethyl; m is —(CH 2 ) n —, wherein n is an integer from 0 to 4, inclusive; and, when r is hydrogen, at least one of q 1 , q 2 , q 3 , and q 4  is also hydrogen.  
       
     
     
         4 . The oxygen barrier composition of  claim 3 , wherein y is greater than or equal to 1, z is greater than or equal to 1, n is 1, and q 1 , q 2 , q 3 , q 4 , and r are hydrogen.  
     
     
         5 . The oxygen barrier composition of  claim 2 , further comprising a transition metal catalyst.  
     
     
         6 . The oxygen barrier composition of  claim 5 , wherein the transition metal catalyst is a cobalt salt.  
     
     
         7 . The oxygen barrier composition of  claim 6 , wherein the cobalt salt is selected from cobalt oleate, cobalt stearate, or cobalt neodecanoate.  
     
     
         8 . The oxygen barrier composition of  claim 2 , further comprising a photoinitiator.  
     
     
         9 . The oxygen barrier composition of  claim 8 , wherein the photoinitiator is selected from benzophenone derivatives containing at least two benzophenone moieties and having the formula: 
       A a (B) b   wherein    A is a bridging group selected from sulfur; oxygen; carbonyl; —SiR″ 2 —, wherein each R″ is individually selected from alkyl groups containing from 1 to 12 carbon atoms, aryl groups containing 6 to 12 carbon atoms, or alkoxy groups containing from 1 to 12 carbon atoms; —NR′″—, wherein R′″ is an alkyl group containing 1 to 12 carbon atoms, an aryl group containing 6 to 12 carbon atoms, or hydrogen; or an organic group containing from 1 to 50 carbon atoms;    a is an integer from 0 to 11;    B is a substituted or unsubstituted benzophenone group; and    b is an integer from 2 to 12.    
     
     
         10 . The oxygen barrier composition of  claim 9 , wherein the photoinitiator is selected from dibenzoyl biphenyl, substituted dibenzoyl biphenyl, benzoylated terphenyl, substituted benzoylated terphenyl, tribenzoyl triphenylbenzene, substituted tribenzoyl triphenylbenzene, benzoylated styrene oligomer, or substituted benzoylated styrene oligomer.  
     
     
         11 . The oxygen barrier composition of  claim 2 , further comprising an antioxidant.  
     
     
         12 . The oxygen barrier composition of  claim 11 , wherein the antioxidant is selected from 2,6-di(t-butyl)-4-methylphenol(BHT), 2,2′-methylene-bis(6-t-butyl-p-cresol), triphenylphosphite, tris-(nonylphenyl)phosphite, vitamin E, tetra-bismethylene 3-(3,5-ditertbutyl-4-hydroxyphenyl)-propionate methane, or dilaurylthiodipropionate.  
     
     
         13 . The oxygen barrier composition of  claim 2 , wherein the composition is a blend comprising the modified EVOH and an unmodified EVOH.  
     
     
         14 . The oxygen barrier composition of  claim 13 , wherein the blend comprises from about 5 wt % to about 20 wt % modified EVOH.  
     
     
         15 . A packaging article, comprising: 
 an oxygen barrier layer, which comprises a modified ethylene vinyl alcohol polymer (EVOH) comprising an oxygen scavenging functional group.    
     
     
         16 . The packaging article of  claim 15 , wherein the modified EVOH comprises structures IV, V, and VI:  
       
         
           
           
               
               
           
         
         wherein x is an integer greater than or equal to 1, y is an integer greater than or equal to 1, z is an integer greater than or equal to 1, and R comprises a cycloalkenyl group.  
       
     
     
         17 . The packaging article of  claim 16 , wherein R has structure II:  
       
         
           
           
               
               
           
         
         wherein q 1 , q 2 , q 3 , q 4 , and r are independently selected from hydrogen, methyl, or ethyl; m is —(CH 2 ) n —, wherein n is an integer from 0 to 4, inclusive; and, when r is hydrogen, at least one of q 1 , q 2 , q 3 , and q 4  is also hydrogen.  
       
     
     
         18 . The packaging article of  claim 17 , wherein y is greater than or equal to 1, z is greater than or equal to 1, n is 1, and q 1 , q 2 , q 3 , q 4 , and r are hydrogen.  
     
     
         19 . The packaging article of  claim 16 , comprising two or more oxygen barrier layers which comprise a modified ethylene vinyl alcohol polymer (EVOH) comprising an oxygen scavenging functional group.  
     
     
         20 . The packaging article of  claim 16 , further comprising a transition metal catalyst in the oxygen barrier layer or a layer adjacent to the oxygen barrier layer.  
     
     
         21 . The packaging article of  claim 20 , wherein the transition metal catalyst is a cobalt salt.  
     
     
         22 . The packaging article of  claim 21 , wherein the cobalt salt is selected from cobalt oleate, cobalt stearate, or cobalt neodecanoate.  
     
     
         23 . The packaging article of  claim 16 , further comprising a photoinitiator in the oxygen barrier layer.  
     
     
         24 . The packaging article of  claim 23 , wherein the photoinitiator is selected from benzophenone derivatives containing at least two benzophenone moieties and having the formula: 
       A a (B) b   wherein    A is a bridging group selected from sulfur; oxygen; carbonyl; —SiR″ 2 —, wherein each R″ is individually selected from alkyl groups containing from 1 to 12 carbon atoms, aryl groups containing 6 to 12 carbon atoms, or alkoxy groups containing from 1 to 12 carbon atoms; —NR′″—, wherein R′″ is an alkyl group containing 1 to 12 carbon atoms, an aryl group containing 6 to 12 carbon atoms, or hydrogen; or an organic group containing from 1 to 50 carbon atoms;    a is an integer from 0 to 11;    B is a substituted or unsubstituted benzophenone group; and    b is an integer from 2 to 12.    
     
     
         25 . The packaging article of  claim 24 , wherein the photoinitiator is selected from dibenzoyl biphenyl, substituted dibenzoyl biphenyl, benzoylated terphenyl, substituted benzoylated terphenyl, tribenzoyl triphenylbenzene, substituted tribenzoyl triphenylbenzene, benzoylated styrene oligomer, or substituted benzoylated styrene oligomer.  
     
     
         26 . The packaging article of  claim 16 , further comprising an antioxidant in the oxygen barrier layer.  
     
     
         27 . The packaging article of  claim 26 , wherein the antioxidant is selected from 2,6-di(t-butyl)-4-methylphenol(BHT), 2,2′-methylene-bis(6-t-butyl-p-cresol), triphenylphosphite, tris-(nonylphenyl)phosphite, vitamin E, tetra-bismethylene 3-(3,5-ditertbutyl-4-hydroxyphenyl)-propionate methane, or dilaurylthiodipropionate.  
     
     
         28 . The packaging article of  claim 16 , wherein the oxygen barrier layer comprises a blend of the modified EVOH and an unmodified EVOH.  
     
     
         29 . The packaging article of  claim 28 , wherein the blend comprises from about 5 wt % to about 20 wt % modified EVOH.  
     
     
         30 . The packaging article of  claim 16 , further comprising a second oxygen barrier layer not comprising a modified EVOH.  
     
     
         31 . The packaging article of  claim 30 , wherein the second oxygen barrier layer comprises poly(ethylene vinyl alcohol) (EVA), polyacrylonitrile, polyvinyl chloride (PVC), poly(vinylidene dichloride), polyethylene terephthalate (PET), or polyamide.  
     
     
         32 . The packaging article of  claim 16 , further comprising a structural layer.  
     
     
         33 . The packaging article of  claim 32 , wherein the structural layer comprises polyethylene, low density polyethylene, very low density polyethylene, ultra-low density polyethylene, high density polyethylene, polypropylene, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), nylon, polyvinyl chloride, ethylene-vinyl acetate, ethylene-alkyl (meth)acrylates, ethylene-(meth)acrylic acid, or ethylene-(meth)acrylic acid ionomers.  
     
     
         34 . The packaging article of  claim 33 , wherein the structural layer comprises PET.  
     
     
         35 . The packaging article of  claim 16 , further comprising a moisture barrier layer.  
     
     
         36 . The packaging article of  claim 35 , wherein the moisture barrier layer comprises polyethylene, polyethylene terephthalate (PET), or a mixture thereof.  
     
     
         37 . The packaging article of  claim 16 , further comprising an oxygen scavenging layer.  
     
     
         38 . The packaging article of  claim 37 , wherein the oxygen scavenging layer is a liner, coating, sealant, gasket, adhesive insert, non-adhesive insert, or fibrous mat insert in the packaging article.  
     
     
         39 . The packaging article of  claim 16 , wherein the packaging article is in the form of a single layer film, a multilayer film, a single layer rigid article, or a multilayer rigid article.  
     
     
         40 . A method of making a modified ethylene vinyl alcohol polymer (EVOH) comprising an oxygen scavenging functional group, comprising: 
 (i) providing (a) an ethylene vinyl alcohol (EVOH) copolymer, (b) an aldehyde comprising an olefinic or benzylic group, and (c) a catalyst; and    (ii) reacting the EVOH copolymer and the aldehyde in the presence of the catalyst under temperature and pressure sufficient to form the modified ethylene vinyl alcohol polymer.    
     
     
         41 . The method of  claim 40 , wherein the modified EVOH comprises structures IV, V, and VI:  
       
         
           
           
               
               
           
         
         wherein x is an integer greater than or equal to 1, y is an integer greater than or equal to 1, z is an integer greater than or equal to 1, and R comprises a cycloalkenyl group.  
       
     
     
         42 . The method of  claim 41 , wherein R has structure II:  
       
         
           
           
               
               
           
         
         wherein q 1 , q 2 , q 3 , q 4 , and r are independently selected from hydrogen, methyl, or ethyl; m is —(CH 2 ) n —, wherein n is an integer from 0 to 4, inclusive; and, when r is hydrogen, at least one of q 1 , q 2 , q 3 , and q 4  is also hydrogen; and  
         the aldehyde has structure III:  
         
           
             
             
                 
                 
             
           
           wherein q 1 , q 2 , q 3 , q 4 , and r are independently selected from hydrogen, methyl, or ethyl; m is —(CH 2 ) n —, wherein n is an integer from 0 to 4, inclusive; and, when r is hydrogen, at least one of q 1 , q 2 , q 3 , and q 4  is also hydrogen.  
         
       
     
     
         43 . The method of  claim 42 , wherein the aldehyde is tetrahydrobenzaldehyde (THBE).  
     
     
         44 . The method of  claim 43 , wherein the catalyst is selected from hydrochloric acid, hydrofluoric acid, a transition metal catalyst, sulfuric acid, or toluene sulfonic acid.  
     
     
         45 . The method of  claim 41 , wherein the reaction is carried out as a solution process, a bulk process, a suspension process, or a melt process.  
     
     
         46 . The method of  claim 41 , further comprising blending the modified EVOH with an unmodified EVOH.  
     
     
         47 . A method of making a modified ethylene vinyl alcohol polymer (EVOH) comprising an oxygen scavenging functional group, comprising: 
 (i) providing (a) an ethylene vinyl acetate (EVA) copolymer and (b) an aldehyde comprising an olefinic or benzylic group;    (ii) hydrolyzing the EVA copolymer in an aqueous solution, to form an EVOH copolymer; and    (iii) reacting the EVOH and the aldehyde, to form the modified EVOH.    
     
     
         48 . The method of  claim 47 , wherein the modified EVOH comprises structures IV, V, and VI:  
       
         
           
           
               
               
           
         
         wherein x is an integer greater than or equal to 1, y is an integer greater than or equal to 1, z is an integer greater than or equal to 1, and R comprises a cycloalkenyl group.  
       
     
     
         49 . The method of  claim 48 , wherein R has structure II:  
       
         
           
           
               
               
           
         
         wherein q 1 , q 2 , q 3 , q 4 , and r are independently selected from hydrogen, methyl, or ethyl; m is —(CH 2 ) n —, wherein n is an integer from 0 to 4, inclusive; and, when r is hydrogen, at least one of q 1 , q 2 , q 3 , and q 4  is also hydrogen; and  
         the aldehyde has structure III:  
         
           
             
             
                 
                 
             
           
         
         wherein q 1 , q 2 , q 3 , q 4 , and r are independently selected from hydrogen, methyl, or ethyl; m is —(CH 2 ) n —, wherein n is an integer from 0 to 4, inclusive; and, when r is hydrogen, at least one of q 1 , q 2 , q 3 , and q 4  is also hydrogen.  
       
     
     
         50 . A method of forming a packaging article comprising an oxygen barrier layer, comprising: 
 (i) providing an oxygen barrier composition comprising a modified ethylene vinyl alcohol polymer (EVOH) comprising an oxygen scavenging functional group; and    (ii) forming the oxygen barrier composition into the packaging article or a layer thereof.    
     
     
         51 . The method of  claim 50 , wherein the modified EVOH comprises structures IV, V, and VI:  
       
         
           
           
               
               
           
         
         wherein x is an integer greater than or equal to 1, y is an integer greater than or equal to 1, z is an integer greater than or equal to 1, and R comprises a cycloalkenyl group.  
       
     
     
         52 . The method of  claim 51 , wherein R has structure II:  
       
         
           
           
               
               
           
         
         wherein q 1 , q 2 , q 3 , q 4 , and r are independently selected from hydrogen, methyl, or ethyl; m is —(CH 2 ) n —, wherein n is an integer from 0 to 4, inclusive; and, when r is hydrogen, at least one of q 1 , q 2 , q 3 , and q 4  is also hydrogen.  
       
     
     
         53 . The method of  claim 51 , wherein the forming step comprises forming a transition metal catalyst into the oxygen barrier layer or a layer adjacent to the oxygen barrier layer of the packaging article.  
     
     
         54 . The method of  claim 51 , wherein the oxygen barrier composition further comprises a photoinitiator.  
     
     
         55 . The method of  claim 51 , wherein the oxygen barrier composition further comprises an antioxidant.  
     
     
         56 . The method of  claim 51 , wherein the oxygen barrier composition comprises a blend of the modified EVOH and an unmodified EVOH.  
     
     
         57 . The method of  claim 56 , wherein the blend comprises from about 5 wt % to about 20 wt % modified EVOH.  
     
     
         58 . The method of  claim 51 , wherein two or more oxygen barrier layers of the packaging article are formed in the forming step.  
     
     
         59 . The method of  claim 51 , wherein the forming step further comprises forming a second oxygen barrier layer not comprising a modified EVOH in the packaging article.  
     
     
         60 . The method of  claim 51 , wherein the forming step further comprises forming a structural layer in the packaging article.  
     
     
         61 . The method of claim  60 , wherein the structural layer comprises PET.  
     
     
         62 . The method of  claim 51 , wherein the forming step comprises forming a multilayer rigid container comprising, from exterior to interior: a structural layer comprising PET; the oxygen barrier layer; and a structural layer comprising PET.  
     
     
         63 . The method of  claim 51 , wherein the forming step further comprises forming a moisture barrier layer in the packaging article.  
     
     
         64 . The method of  claim 51 , wherein the forming step further comprises forming an oxygen scavenging layer in the packaging article.  
     
     
         65 . The method of  claim 51 , wherein the forming step comprises forming the packaging article as a single layer film, a multilayer film, a single layer rigid article, or a multilayer rigid article.