Packaging articles in containers having self-adhering inner layers

Abstract

An article is packaged in a multilayer flexible plastic sheet having a layer of a self-adhering plastic material and a layer of normally solid, thermoplastic organic polymer by (1) inserting the article between two opposing portions of the multilayer plastic sheet such that the layer of self-adhering plastic material faces the article; (2) collapsing the opposing portions into conforming contact with the article such that essentially all gases are permitted to pass out of the resulting package; and (3) sealing together the opposing contacting surfaces of said opposing portions to form a hermetically sealed package such that the self-adhering plastic material remains in clinging, conforming contact with the article and itself upon puncture of the multilayer plastic sheet.

What is claimed is: 
     
       1. A method of packaging comprising the steps of (1) inserting an article between two opposing sheet portions .Iadd.of a container.Iaddend., each of said .[.sheets.]. .Iadd.sheet portions .Iaddend.being .Iadd.made of .Iaddend.flexible, multilayer plastic sheet .Iadd.material .Iaddend.having a first layer of a self-adhering plastic material facing the article and a second layer of a nontacky normally solid .[.plastic.]. .Iadd.thermoplastic, organic polymeric .Iaddend.material different from the first layer and providing structural strength to the multilayer plastic sheet, said self-adhering material .Iadd.being a copolymer of olefin and a monomer selected from the group consisting of unsaturated ester and unsaturated carboxylic acid, said copolymer being .Iaddend.capable of bonding to itself at temperatures below the heat distortion point of said nontacky normally solid plastic material; (2) collapsing the opposing sheet portions into clinging, conforming contact with the article .[.such that.]. and forming .Iadd.a flange-like peripheral interface portion defined by the opposing contacting surfaces of the sheet portions extending around at least a portion of the periphery of the container, by removing .Iaddend.essentially all gases .[.are permitted to pass out of the resulting package.]. .Iadd.and creating a vacuum in said package.Iaddend.; and (3) .Iadd.heat .Iaddend.sealing together .Iadd.without simultaneous mechanical pressure the flange-like peripheral interface portions defined by .Iaddend.the opposing contacting surfaces of said sheet portions .Iadd.with said container under a pressure differential between the ambient pressure on the outside of the container and the vacuum in said container .Iaddend.to form a hermetically sealed package which remains in clinging, conforming contact with said article upon puncture of said sheet portions. 
     
     
       2. A method according to claim 1 wherein the self-adhering plastic material is capable of bonding to itself at temperatures between about 80° and about 100° C. and step (3) is carried out by heating the resulting package to a temperature between about 80° and about 100° C. 
     
     
       3. A method according to claim 2 wherein the self-adhering plastic material is a .[.polymer.]. .Iadd.copolymer of olefin and an unsaturated ester .Iaddend.containing at least 5 weight percent of .[.a.].  polymerized unsaturated ester. 
     
     
       4. The method according to claim 3 wherein the unsaturated ester is vinyl acetate. 
     
     
       5. The method according to claim 4 wherein the unsaturated ester polymer is an ethylene/vinyl acetate copolymer. 
     
     
       6. The method according to claim 2 wherein the self-adhering plastic material is polyvinyl acetate. 
     
     
       7. The method according to claim 2 wherein step (3) is carried out by immersing the resulting package in boiling water. 
     
     
       8. The method according to claim 1 wherein the self-adhering plastic material is an olefin/unsaturated acid copolymer containing at least 3 weight percent of unsaturated acid. 
     
     
       9. The method according to claim 8 wherein the copolymer is an ethylene/acrylic acid copolymer. .[.10. The method according to claim 1 wherein the opposing sheet portions in the form of a container having an opening are collapsed into clinging, conforming contact with the article 
     
     
        by evacuating all gases from the container..]. 11. A method of packaging comprising the steps of (1) inserting an article into a container having two sheet portions superimposed upon one another and sealed together around at least a portion of their periphery, said container being provided with an opening, said .[.sheets.]. .Iadd.sheet portions .Iaddend.being .Iadd.made of .Iaddend.flexible, multilayer plastic sheet .Iadd.material .Iaddend.having a first layer of a self-adhering plastic material facing the article and a second layer of a normally solid, heat-shrinkable, plastic material different from the first layer and providing structural strength to the multilayer plastic sheet, said self-adhering material .Iadd.being a copolymer of olefin and a monomer selected from the group consisting of unsaturated ester and unsaturated carboxylic acid, said copolymer .Iaddend.being capable of bonding to itself at .Iadd.a .Iaddend.temperature below the heat distortion temperature of the heat-shrinkable plastic material and (2) shrinking the container into conforming contact with the article .Iadd.and forming a flange-like peripheral interface portion defined by the opposing contacting surfaces of the sheet portions extending about at least a portion of the periphery of the container .Iaddend.such that essentially .Iadd.all .Iaddend.gases are permitted to pass out of said opening while simultaneously .Iadd.heat .Iaddend.sealing together .Iadd.the flange-like peripheral interface portions defined by .Iaddend.the opposing, contacting surfaces of said sheet portions .Iadd.without simultaneous mechanical pressure .Iaddend.to form a hermetically sealed package which remains in clinging, conforming contact with said article upon puncture of said 
     
     
        package. 12. The method according to claim 11 wherein the heat shrinkable .[.polymer.]. .Iadd.material .Iaddend.is a vinylidene chloride/vinyl chloride copolymer. .[.13. A packaged article comprising an article enclosed in a flexible, multilayer plastic sheet having a layer of a self-adhering plastic material, said layer facing the article, and a shrunk layer of a heat-shrinkable, normally solid, plastic material different from the first layer and providing structural strength to the plastic sheet, said self-adhering plastic material being capable of bonding to itself at temperatures below the heat distortion point of the heat-shrinkable plastic material, said plastic sheet being in clinging, conforming contact with the article and all opposing contacting surfaces of the plastic sheet being sealed together such that the plastic sheet remains in clinging conforming contact with said article upon puncture of said sheet..]. .[.14. A container comprising at least two opposing sheet portions of a flexible, multilayer plastic sheet having a lining layer of a self-adhering plastic material and a layer outside of the lining layer of a heat-shrinkable normally solid, plastic material different from the first layer and providing structural strength for the plastic sheet, said self-adhering plastic material being capable of bonding to itself at temperatures below the heat distortion point of the heat-shrinkable plastic material, the opposing sheet portions being superimposed on one another and sealed together around at least a portion of their periphery, said container being provided with an opening..]. .[.15. The container according to claim 14 wherein the self-adhering plastic material is an unsaturated ester polymer which is capable of bonding to itself at a temperature between about 80° and about 100° C..]. .[.16. The container according to claim 15 wherein the unsaturated ester polymer is an ethylene/vinyl acetate copolymer containing at least 5 weight percent of polymerized vinyl acetate..]. .[.17. The container according to claim 14 wherein the heat-shrinkable polymer is a heat-shrinkable 
     
     
        vinylidene chloride/vinyl chloride copolymer..]. 18. A method of packaging .[.according to claim 1.]. comprising the steps of (1) inserting an article between two opposing sheet portions, each of said sheets being flexible, multilayer plastic sheet having a first layer of a self-adhering plastic material facing the article and a second layer of nontacky, normally solid material different from the first layer and providing structural strength to the multilayer plastic sheet.Iadd., said self-adhering material being capable of bonding to itself at temperatures below the heat distortion point of said nontacky normally solid plastic material; .Iaddend.(2) sealing the sheet portions together in a discontinuous manner such that air passages remain; (3) collapsing the opposing sheet portions into clinging, conforming contact with the article such that essentially all gases are permitted to pass out of the resulting package; such that remaining air passages are closed; and (4) sealing together the opposing contacting surfaces of said sheet portions to form a hermetically sealed package which remains in clinging, conforming contact 
     
     
        with said article upon puncture of said sheet portions. 19. A method of packaging .[.according to claim 1.]. comprising the steps of (1) inserting an article into a flexible multiplex bag having individual lining walls of a self-adhering plastic material and individual outer walls of a nontacky, normally solid plastic material different from the lining walls and providing structural strength to the multiplex bag.Iadd., said self-adhering material being capable of bonding to itself at temperatures below the heat distortion point of said nontacky normally solid plastic material; .Iaddend.(2) collapsing the multiplex bag into clinging, conforming contact with the article such that essentially all gases are permitted to pass out of the resulting package; and (3) sealing together the opposing contacting surfaces of said lining walls to form a hermetically sealed package which remains in clinging, conforming contact 
     
     
        with said article upon puncture of said multiplex bag. 20. The method according to claim 19 wherein the individual walls of the multiplex bag are each perforated such that the perforations of one wall are out of 
     
     
        registration with the perforations of the next adjacent walls. 21. The 
     
     
        multiplex bag according to claim 19. 22. The multiplex bag according to 
     
     
        claim 20. 23. The method of packaging according to claim 18 comprising the steps of (1) inserting an article between two opposing sheet portions, each of said sheets being a flexible multilayer plastic sheet having a first layer of a self-adhering plastic material capable of bonding to itself at temperatures between about 80° and 100° C. facing the article and a second layer of nontacky, normally solid plastic material different from the first layer and providing structural strength to the multilayer plastic sheet, said sheet portions being sealed together in a discontinuous manner such that mazelike air passages remain, (2) collapsing the opposing sheet portions into clinging, conforming contact with the article such that essentially all gases are permitted to pass out of the resulting package and the remaining mazelike air passages are closed and (3) sealing together the opposing contacting surfaces of said sheet portions to form a hermetically sealed package which remains in clinging, conforming contact with said article upon puncture of said sheet 
     
     
        portions. 24. The method according to claim 23 wherein steps (2) and (3) are carried out in a single operation by heating the resulting package in a vacuumizing chamber to a temperature between about 80° and about 
     
     
        100° C. 25. A container comprising at least two opposing sheet portions of a flexible, multilayer plastic sheet having a lining layer of a self-adhering plastic material and a layer outside of the lining layer of a nontacky normally solid plastic material different from the first layer and providing structural strength to the multilayer plastic sheet, said self-adhering material being capable of bonding to itself at temperatures below the heat distortion point of the nontacky normally solid plastic material, the opposing sheet portions being superimposed on one another and sealed together in a discontinuous manner to form discontinuous seals such that air passages remain between the inside of 
     
     
        said container and the outside. 26. The container according to claim 25 wherein the discontinuous seals are maze seals forming mazelike air 
     
     
        passages therebetween. 27. The container according to claim 25 wherein the discontinuous seals are skip seals. .Iadd. 28. A method as in claim 1 wherein said self-adhering material is a copolymer of ethylene and vinyl acetate providing sufficient adhesion to cling to the article being packaged and to seal at points of contact between the layers and wherein 
     
     
        said second layer is nylon. .Iaddend. .Iadd. 29.  A method as in claim 1 wherein said self-adhering material is a copolymer of ethylene and acrylic acid providing sufficient adhesion to cling to the article being packaged and to seal at points of contact between the layers and wherein said second layer is nylon. .Iaddend..Iadd. 30. A method as in claim 1 wherein said self-adhering material is a copolymer of ethylene and vinyl acetate providing sufficient adhesion to cling to the article being packaged and to seal at points of contact between the layers and wherein said second layer material is Saran. .Iaddend..Iadd. 31. A method as in claim 1 wherein said self-adhering material is a copolymer of ethylene and acrylic acid providing sufficient adhesion to cling to the article being packaged and to seal at points of contact between the layers and wherein said second layer is Saran. .Iaddend. .Iadd. 32. A method of packaging comprising the steps of (1) inserting an article between two opposing sheet portions, said sheet portions being made of flexible, multilayer plastic sheet material having a first layer of a self-adhering plastic material facing the article and a second layer of a normally solid plastic material different from the first layer and providing structural strength to the multilayer plastic sheet, said self-adhering material being a copolymer of olefin and a monomer selected from the group consisting of unsaturated ester and unsaturated carboxylic acid, said copolymer being capable of bonding to itself at a temperature below the heat distortion temperature of the plastic material and providing adhesion sufficient to cling to the article being packaged and (2) collapsing the opposing sheet portions into conforming contact with the article and forming a flange-like peripheral interface portion defined by the opposing sheet portions extending about at least a portion of the periphery of the container such that essentially all gases are permitted to pass out of the resulting container and heat sealing together without simultaneous mechanical pressure the flange-like peripheral interface portions defined by the opposing, contacting surfaces of said sheet portions to form a hermetically sealed package which remains in clinging, conforming contact with said article upon puncture of said package. .Iaddend..Iadd. 33. A method of packaging comprising the steps of (1) inserting an article into a container having two sheet portions superimposed upon one another and sealed together around at least a portion of their periphery, said container being provided with an opening, said sheet portions being made of flexible, multi-layer plastic sheet material having a first layer of a self-adhering plastic material facing the article and a second layer of a nontacky normally solid, non-heat shrinkable, thermoplastic organic polymeric material different from the first layer and providing structural strength to the multilayer plastic sheet, said self-adhering material being a copolymer of olefin and an unsaturated ester capable of bonding to itself at temperatures below the heat distortion temperature of the non-heat shrinkable plastic material and providing adhesion sufficient to cling to the article being packaged, (2) evacuating gases from said container to collapse the container into conforming contact with the article, creating a vacuum in said container, and simultaneously forming a flange-like peripheral interface portion defined by the opposing contacting surfaces of said opposing sheet portions extending about at least a portion of the periphery of the container; and (3) heat sealing together without simultaneous mechanical pressure the flange-like peripheral interface portions defined by the opposing contacting surfaces of said sheet portions with the container under a pressure differential between the ambient pressure on the outside of the container and the vacuum in said container to form a hermetically sealed package which remains in clinging, conforming contact with said article upon, puncture of said sheet portions. .Iaddend..Iadd. 34. A method of packaging comprising the steps of (1) inserting an article into a container having two sheet portions superimposed upon one another and sealed together around at least a portion of their periphery, said container being provided with an opening, said sheet portions being made of flexible, multi-layer plastic sheet material having a first layer of a self-adhering plastic material facing the article and a second layer of a nontacky normally solid, heat shrinkable, thermoplastic organic polymeric material different from the first layer and providing structural strength to the multilayer plastic sheet, said self-adhering material being a copolymer of olefin and an unsaturated ester capable of bonding to itself at temperatures below the heat distortion temperature of the heat shrinkable plastic material and providing adhesion sufficient to cling to the article being packaged; (2) evacuating gases from said container, and simultaneously forming a flange-like peripheral interface portion defined by the opposing contacting surface of said opposing sheet portions extending about at least a portion of the periphery of the container; and (3) subsequently heat shrinking said sheet portions and heat sealing together without simultaneous mechanical pressure the flange-like peripheral interface portions defined by the opposing contacting surfaces of said sheet portions with the container under a pressure differential between the ambient pressure on the outside of the container and the vacuum in said container to form a hermetically sealed package which remains in clinging, conforming contact with said article upon puncture of said sheet portions. .Iaddend..Iadd. 35. The method according to claim 33 wherein said self-adhering material is a copolymer of ethylene and vinylacetate and said second layer is nylon and said flange-like peripheral interface portion extends about the entire periphery of said container. .Iaddend..Iadd. 36. The method according to claim 33 wherein said self-adhering material is a copolymer of ethylene and acrylic acid and said second layer is nylon and said flange-like peripheral interface portion extends about the entire periphery of said container. .Iaddend..Iadd. 37. The method according to claim 34 wherein said self-adhering material is a copolymer of ethylene and vinyl acetate and said second layer material is Saran. .Iaddend..Iadd. 38. The method according to claim 34 wherein said self-adhering material is a copolymer of ethylene and acrylic acid and said second layer is Saran. .Iaddend.