Multilayered packaging material

Abstract

A multilayered polymeric structure for use as a packaging container comprising a first layer of oxygen barrier material and a second protective layer bonded to the first layer where the oxygen barrier layer material is selected from the group consisting of saponified ethylene-vinyl acetate copolymer, polyamide, polyvinyl alcohol, modification products thereof, and mixtures thereof, and the second protective layer comprises a polymer and an inorganic filler in an amount sufficient to further enhance the moisture barrier property of the outer protective layer over what it would be in the absence of the filler.

We claim: 
     
         1 . A process for protecting an oxygen sensitive substance comprising the step of enclosing the substance in a package, said package comprising a laminated multilayer material where the multilayer material comprises
 (i) a first layer of oxygen barrier material having a first surface and an opposing second surface,   (ii) a protective second layer having a surface that is bonded to at least a portion of the first surface of the first layer in a face to face relationship, and;   (iii) a protective third layer having a surface that is bonded to at least a portion of the second surface of the first layer in a face to face relationship,   
       where the oxygen barrier layer material is selected from the group consisting of saponified ethylene-vinyl acetate copolymer, polyamide, polyvinyl alcohol, and mixtures of the foregoing, the protective second and third layers comprise a moisture barrier polymer, and either one or both of the protective layers comprise inorganic filler particles dispersed in the moisture barrier polymer in an amount effective to show an enhancement of the rate of recovery of the oxygen transmission rate of the structure after a retort shock over what it would be in the absence of the filler particles, where the filler particles comprise a material with a moisture capacity of greater than 0.05% moisture by weight of material, and where retort shock is a process in which the structure is subjected to moisture vapor in the form of steam at a temperature of at least 125° C. for at least 33 minutes impinging on the one or both of the protective layers. 
     
     
         2 . The process of  claim 1  in which the polymer is selected from the group consisting of polypropylene, polystyrene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, polyethylene terephthalate, polybutylene terehthalate, polycarbonates, acrylonitrile-styrene-butadiene copolymer, polyphenylene oxide, modification products and mixtures thereof. 
     
     
         3 . The process of  claim 1  in which the multilayer material further comprises a fourth and a fifth adhesive layers in between the first and second, and first and third layers respectively. 
     
     
         4 . The process of claim  26  in which the second layer further comprises a skin layer adjacent to the side of the second layer opposite to the first layer. 
     
     
         5 . The process of  claim 1  in which the third layer comprises a skin layer adjacent to the side of the third layer opposite to the first layer. 
     
     
         6 . The process of  claim 4  in which the second layer comprises a skin layer adjacent to the side of the third layer opposite to the first layer. 
     
     
         7 . The process of  claim 4  in which the skin layer comprises a polyolefin. 
     
     
         8 . The process of  claim 4  in which the skin layer comprises a polyolefin. 
     
     
         9 . The process of  claim 6  in which the skin layers on the second and third layers comprise polyolefins. 
     
     
         10 . The process of  claim 3  in which the fourth and fifth layers comprise an adhesive polymer. 
     
     
         11 . The process of  claim 10  in which the adhesive polymer comprises a copolymer of ethylene and maleic anhydride. 
     
     
         12 . The process of  claim 1  in which the filler particles comprise fillers selected from the group consisting of talc, calcium carbonate, calcium oxide, silica, barium sulfate, wollastonite, mica, clay, kaolin, silica, diatomaceous earth, alumina, zinc white, magnesium oxide, calcium sulfite, calcium sulfate, calcium silicate, glass powders, glass fibers, silane-treated glass fibers, asbestos, gypsum fibers, and combinations thereof. 
     
     
         13 . The process of  claim 1  in which the filler further comprises a surface coating over at least a portion of its surface. 
     
     
         14 . The process of  claim 1  in which the filler is present in an amount from 1.5% to 50% by weight of polymer plus filler in the second layer, the third layer, or both. 
     
     
         15 . The process of  claim 12  in which the filler is present in an amount from 10% to 40% by weight of polymer plus filler in the second layer, the third layer, or both. 
     
     
         16 . The process of  claim 1  in which at least 10% of the filler particles have an aspect ratio of between 1 and 120. 
     
     
         17 . The process of  claim 16  in which at least 10% of the filler particles have an aspect ratio of between 5 and 40. 
     
     
         18 . The process of  claim 1  in which the filler particles have a number average particle size in their smallest dimension of between 0.5 and 15 microns. 
     
     
         19 . The process of  claim 18  in which the filler particles have a number average particle size in their smallest dimension of between 1.5 and 10 microns.