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.

1 . A laminated multilayered sheet structure for use in a packaging container, said structure comprising:
 (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 structure of  claim 1  in which the rate of recovery of oxygen transmission is measured by the integral of a plot of oxygen transmission rate versus time where time is measured from the end of the retorting process for at least 50 hours and enhancement means that the integral in the presence of particles is less than that in the absence of particles. 
     
     
         3 . The structure of  claim 1  in which the moisture barrier polymer in the second and third layers is independently selected from the group consisting of polypropylene, polystyrene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, polyethylene terephthalate, polybutylene terephthalate, polycarbonates, acrylonitrile-styrene-butadiene copolymer, polyphenylene oxide, modification products and mixtures thereof. 
     
     
         4 . The structure of  claim 1  which further comprises a fourth and fifth adhesive layers in between the first and second, and first and third layers respectively. 
     
     
         5 . The structure of  claim 1  in which the second layer further comprises a skin layer bonded to the side of the second layer that is not the side bonded to the first layer. 
     
     
         6 . The structure of  claim 4  in which the third layer further comprises a skin layer bonded to the side of the third layer that is not the side that is bonded to the first layer. 
     
     
         7 . The structure of  claim 6  in which the second layer comprises a skin layer bonded to the side of the second layer that is not the side that is bonded to the first layer. 
     
     
         8 . The structure of  claim 5  in which the skin layer comprises a polyolefin. 
     
     
         9 . The structure of  claim 6  in which the skin layer comprises a polyolefin. 
     
     
         10 . The structure of  claim 6  in which the skin layers on the second and third layers comprise polyolefins. 
     
     
         11 . The structure of  claim 3  in which the fourth and fifth adhesive layers comprise an adhesive polymer. 
     
     
         12 . The structure of  claim 10  in which the adhesive polymer comprises a copolymer of ethylene and maleic anhydride. 
     
     
         13 . The structure of  claim 1  in which the filler particles comprise material selected from the group consisting of 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. 
     
     
         14 . The structure of  claim 1  in which the filler particles further comprise a surface coating over at least a portion of their surface. 
     
     
         15 . The structure of  claim 1  in which the filler particles are present in an amount from 1.5% to 50% by weight of polymer plus filler in the second layer, the third layer, or both. 
     
     
         16 . The structure of  claim 14  in which the filler particles are present in an amount from 10% to 40% by weight of polymer plus filler in the second layer, the third layer, or both. 
     
     
         17 . The structure of  claim 1  in which at least 10% of the filler particles have an aspect ratio of between 1 and 120. 
     
     
         18 . The structure of  claim 16  in which at least 10% of the filler particles have an aspect ratio of between 5 and 40. 
     
     
         19 . The structure 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. 
     
     
         20 . The structure 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. 
     
     
         21 . A container comprising walls in which the walls comprise a laminated multilayered sheet structure comprising:
 (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. 
     
     
         22 . The container of  claim 20  where the walls of the container comprise over at least a part of their surface a pigmented skin layer adjacent to the second or third protective layers, or both, on the sides of the second and third layers that are not bonded to the first layer, where the pigmented skin or skins are up to 25% of the total thickness of the container walls or lid or both, in the portion of the side where the skin is present, and the second and third layers then together comprise 5% to 40% of the thickness of the container walls or both in the portion of the side where they are present respectively. 
     
     
         23 . The container of  claim 21  in which one or more adhesive layers bond the first layer to the second and third protective layers and the adhesive layer or layers comprise from 1 to 5% of the total thickness of the container wall in any place. 
     
     
         24 . The container of  claim 21  in which the first layer comprises 1 to 10% of the thickness of the container walls over the portion of the container walls where first layer is present. 
     
     
         25 . The container of  claim 21  in which the pigmented skin comprises a polyolefin. 
     
     
         26 . The container of  claim 20  which is produced by thermoforming. 
     
     
         27 . 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. 
     
     
         28 . The process of  claim 26  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 terephthalate, polycarbonates, acrylonitrile-styrene-butadiene copolymer, polyphenylene oxide, modification products and mixtures thereof. 
     
     
         29 . The process of  claim 26  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. 
     
     
         30 . 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. 
     
     
         31 . The process of  claim 26  in which the third layer comprises a skin layer adjacent to the side of the third layer opposite to the first layer. 
     
     
         32 . The process of  claim 30  in which the second layer comprises a skin layer adjacent to the side of the third layer opposite to the first layer. 
     
     
         33 . The process of  claim 29  in which the skin layer comprises a polyolefin. 
     
     
         34 . The process of  claim 30  in which the skin layer comprises a polyolefin. 
     
     
         35 . The process of  claim 31  in which the skin layers on the second and third layers comprise polyolefins. 
     
     
         36 . The process of  claim 28  in which the fourth and fifth layers comprise an adhesive polymer. 
     
     
         37 . The process of  claim 35  in which the adhesive polymer comprises a copolymer of ethylene and maleic anhydride. 
     
     
         38 . The process of  claim 26  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. 
     
     
         39 . The process of  claim 26  in which the filler further comprises a surface coating over at least a portion of its surface. 
     
     
         40 . The process of  claim 26  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. 
     
     
         41 . The process of  claim 39  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. 
     
     
         42 . The process of  claim 26  in which at least 10% of the filler particles have an aspect ratio of between 1 and 120. 
     
     
         43 . The process of  claim 41  in which at least 10% of the filler particles have an aspect ratio of between 5 and 40. 
     
     
         44 . The process of  claim 26  in which the filler particles have a number average particle size in their smallest dimension of between 0.5 and 15 microns. 
     
     
         45 . The process of  claim 43  in which the filler particles have a number average particle size in their smallest dimension of between 1.5 and 10 microns.