Thermoformable Copolyester Laminate

Abstract

A laminate includes the following substantially coextensive layers in the following order: (a) a non-sealable, self-supporting, thermoformable copolyester film layer having a first surface and a second surface, the second surface constituting an outermost, exposed surface of the laminate; (b) a laminating adhesive layer on the first surface of the thermoformable copolyester film layer; and (c) a self-supporting, thermoformable structural film layer having a first surface and a second surface, the first surface contacting the laminating adhesive layer. Polyethylene terephthalate constitutes at least 80% by weight of the self-supporting thermoformable copolyester film layer; the thermoformable structural film layer includes a polymer selected from the group consisting of polyamides, polypropylene, polyethylene, polyethylene terephthalate, ionomers, ethylene acrylic acid copolymers, ethylene vinyl acetate copolymers, polystyrene, ethylene vinyl alcohol copolymers and polyvinylidene chloride; the thermoformable copolyester film layer, the structural film layer and the laminate each shrink less than 5% in length and width upon exposure to boiling water for five seconds; and the laminate is thermoformable and its chloroform-soluble extractives meet the requirements of paragraph h(1) of 21 CFR §177.1630 as defined herein.

1 . A laminate comprising the following substantially coextensive layers in the following order
 (a) a non-sealable, self-supporting, thermoformable copolyester film layer having a first surface and a second surface, said second surface constituting an outermost, exposed surface of the laminate, wherein the copolyester in the thermoformable copolyester film layer comprises from 90 mol % to 97 mol % of at least one aromatic dicarboxylic acid and correspondingly from 10 mol % to 3 mol % of at least one aliphatic dicarboxylic acid;   (b) a laminating adhesive layer on the first surface of the thermoformable copolyester film layer; and   (c) a self-supporting, thermoformable structural film layer having a first surface and a second surface, said first surface contacting the laminating adhesive layer;   wherein polyethylene terephthalate constitutes at least 80% by weight of the self-supporting thermoformable copolyester film layer;   the thermoformabie structural film layer comprises a polymer selected from the group consisting of polyamides, polypropylene, polyethylene, polyethylene terephthalate, ionomers, ethylene acrylic acid copolymers, ethylene vinyl acetate copolymers, polystyrene, ethylene vinyl alcohol copolymers and polyvinylidene chloride;   the thermoformabie copolyester film layer, the structural film layer and the laminate each shrink less than 5% in length and width upon exposure to bulling water for five seconds; and   the laminate is thermoformable and its chloroform-soluble extractives meet the requirements of paragraph h(1) of 21 CFR §177.1630 as defined herein,   
     
     
         2 . The laminate of  claim 1 , wherein the structural film layer comprises a polyamide. 
     
     
         3 . The laminate of  claim 1 , wherein the structural film layer comprises nylon 6,6. 
     
     
         4 . The laminate of  claim 1 , further comprising a barrier layer substantially coextensive with the copolyester film layer and the structural film layer, on a side of the structural film layer opposite the copolyester film layer, wherein the barrier layer comprises a polymer selected from the group consisting of oriented polyethylene terephthalate, polyvinylidene chloride, ethylene vinyl alcohol copolymers and polyamides. 
     
     
         5 . The laminate of  claim 4 , consisting of the copolyester film layer, the laminating adhesive layer, the structural film layer, and the barrier layer. 
     
     
         6 . The laminate of  claim 4 , wherein the barrier layer comprises polyvinylidene chloride. 
     
     
         7 . The laminate of  claim 4 , wherein the barrier layer is on the second surface of the structural film layer. 
     
     
         8 . The laminate of  claim 1 , consisting of the copolyester film layer, the laminating adhesive layer and the structural film layer. 
     
     
         9 . The laminate of  claim 1 , wherein the laminate is in the shape of a thermoformed receptacle haying a pocket with a flange and an opening, the second surface of the copolyester film layer forming an inner surface of the pocket and a mating surface of the flange. 
     
     
         10 . A package comprising the laminate of  claim 9  and a heat-sealable film, wherein the opening of the receptacle is closed by the heat-sealable film, said heat-sealable film comprising a self-supporting polymeric film having on a surface thereof a substantially coextensive heat-seal layer;
 wherein the heat-seal layer of the heat-sealable film is in contact with and bonded to the mating surface of the flange of the thermoformed receptacle; and 
 wherein chloroform-soluble extractives of the heat-sealable film meet the requirements of paragraph h(1) of 21 CFR §177.1630 as defined herein. 
 
     
     
         11 . The package of  claim 10 , wherein the heat-seal layer comprises an amorphous copolyester. 
     
     
         12 . The package of  claim 10 , wherein the laminate is capable of forming a heat-seal bond to the capping web with a bond strength of at least 250 g/25 mm and at most 2500 g/25 mm. 
     
     
         13 . The package of  claim 10 , further comprising a contained foodstuff. 
     
     
         14 . The package of  claim 10 , wherein the heat-seal layer ruptures and vents the package at a temperature in a range from 150° F. (65.6° C.) to 450° F. (232.2° C.). 
     
     
         15 . The package of  claim 14 , wherein the heat-seal layer ruptures and the package vents only at a temperature above 210° F. (98.9° C.). 
     
     
         16 . The package of  claim 14 , wherein the heat-seal layer ruptures and the package vents only at a temperature above 250° F. (121.1° C.). 
     
     
         17 . The package of  claim 13 , wherein the foodstuff is meat, poultry, or seafood. 
     
     
         18 . A method of packaging a foodstuff, comprising placing the foodstuff in the pocket of the laminate of  claim 9  and subsequently sealing the opening by heat-sealing a film to the flange. 
     
     
         19 . The package of  claim 14 , wherein the foodstuff is meat, poultry, or seafood.