US20120244362A1 - Multi-layer sheet structure - Google Patents

Abstract

A multi-layer sheet structure includes, in an exemplary embodiment, a barrier layer having a first side and a second side, at least one thermoplastic layer on the first side of the barrier layer, and at least one thermoplastic layer on the second side of the barrier layer. A cup shaped container may be molded from the multi-layer sheet structure.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application claims priority to Provisional Patent Application No. 61/466,326 filed Mar. 22, 2011, which is hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
• The field of the invention relates generally to multi-layer sheet structures and more particularly, to thermoplastic multi-layer sheet structures that are moldable, include at least one layer of a polypropylene, and which is produced with sustainable and renewable ingredients.
• Thermoplastic sheets are used in forming various articles, for example, plastic cups and plastic cup shaped containers. Typically, thermoplastic sheets are made from polystyrene resins which may used to form plastic cups and plastic cup shaped containers. Plastic cup shaped containers are sometimes used in single serve coffee maker. Such single, or individual, serve coffee makers typically utilize a single serve fresh ground coffee cup shaped container and the brewed coffee is dispensed directly into a coffee cup. The fresh ground coffee container typically facilitates sealing the coffee grounds in the container until use, so that the coffee grounds are fresh, and typically are sealed at the top with a moisture barrier seal. The cup shaped containers have various sizes which hold only enough coffee to brew one cup of coffee up to a full pot of coffee.
• As explained above, single serve coffee containers are configured to be used once and then discarded. Polystyrene plastic, however, is not as environmentally friendly and has a high carbon foot print, as compared to other types of plastics.
BRIEF DESCRIPTION OF THE INVENTION
• In one aspect, a multi-layer sheet structure is provided. The multi-layer sheet structure includes a barrier layer having a first side and a second side, at least one thermoplastic layer on the first side of the barrier layer, and at least one thermoplastic layer on the second side of the barrier layer.
• In another aspect, a multi-layer sheet structure is provided that includes a barrier layer having a first side and a second side, a first adhesive layer on the first side of the barrier layer, and a second adhesive layer on the second side of the barrier layer. The multi-layer sheet structure also includes a first layer that includes a first polypropylene composition on the first adhesive layer, and a second layer that includes a second polypropylene composition on the second adhesive layer.
• In still another aspect, a method of making a multi-layer sheet structure is provided. The method includes connecting a plurality of extruders to a die configured to extrude a plurality of layers, feeding a plurality of thermoplastic materials to the plurality of extruders, and co-extruding a plurality of layers from the plurality of thermoplastic materials to form the multi-layer sheet structure. The plurality of layers include a barrier layer having a first side and a second side, at least one thermoplastic layer on the first side of the barrier layer, and at least one thermoplastic layer on the second side of the barrier layer.
• In still another aspect, a multi-layer sheet structure is provided. The multi-layer sheet comprising a first layer and a second layer. The first layer comprise a first polypropylene composition and the second layer comprise a second polypropylene composition.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a cross sectional schematic illustration of an example embodiment of a multi-layer sheet structure.
• FIG. 2 is a cross sectional schematic illustration of another embodiment of a multi-layer sheet structure.
• FIG. 3 is a cross sectional schematic illustration of another embodiment of a multi-layer sheet structure.
• FIG. 4 is a cross sectional schematic illustration of another embodiment of a multi-layer sheet structure.
• FIG. 5 is a schematic illustration of an example embodiment of a forming insert.
• FIG. 6 is a perspective view of an example embodiment of a forming base that may be used with the forming insert shown inFIG. 5.
• FIG. 7 is a schematic illustration of another example embodiment of a forming insert.
• FIG. 8 is a perspective view of an example embodiment of a forming base that may be used with the forming insert shown inFIG. 7.
• FIG. 9 is a schematic illustration of another example embodiment of a forming insert.
• FIG. 10 is a perspective view of an example embodiment of a forming base that may be used with the forming insert shown inFIG. 9.
• FIG. 11 is a schematic illustration of another example embodiment of a forming insert.
• FIG. 12 is a perspective view of an example embodiment of a forming base that may be used with the forming insert shown inFIG. 11.
• FIG. 13 is a perspective view of an example embodiment of a mold plug.
• FIG. 14 is a perspective view of another example embodiment of a mold plug.
• FIG. 15 is a perspective view of another example embodiment of a mold plug.
• FIG. 16 is a side view of a cup formed from the forming insert shown inFIG. 5 and the forming base shown inFIG. 6.
• FIG. 17 is a perspective view of the cup shown inFIG. 16.
• FIG. 18 is a side view of a cup formed from the forming insert shown inFIG. 7 and the forming base shown inFIG. 8.
• FIG. 19 is a perspective view of the cup shown inFIG. 18.
• FIG. 20 is a side view of a cup formed from the forming insert shown inFIG. 9 and the forming base shown inFIG. 10.
• FIG. 21 is a perspective view of the cup shown inFIG. 20.
• FIG. 22 is a side view of a cup formed from the forming insert shown inFIG. 11 and the forming base shown inFIG. 12.
• FIG. 23 is a perspective view of the cup shown inFIG. 22.
DETAILED DESCRIPTION OF THE INVENTION
• A multi-layer thermoplastic sheet structure and a method of making the multi-layer thermoplastic sheet structure is described below in detail. The multi-layer sheet structure, in an exemplary embodiment, includes seven layers. Specifically, the sheet structure includes an outer top layer of polypropylene, an inner top layer of polypropylene, a first adhesive layer (tie layer), a barrier layer, a second adhesive layer (tie layer), an inner bottom layer of polypropylene, and an outer bottom layer of polypropylene. Although the sheet structure is specifically described herein as having seven layers, it is contemplated additional layers or fewer layers could be utilized in the sheet. For example, in another embodiment, the sheet structure may include five layers. Specifically, the sheet structure includes a top layer of polypropylene, an adhesive layer (tie layer), a barrier layer, another adhesive layer (tie layer) and a bottom layer of polypropylene. In other embodiments, the multi-layer sheet structure may include from two layers to eight layers. Some examples of a multi-layer sheet structure include a two layer structure that may include two polypropylene layers; a six layer structure that may include a barrier layer, two adhesive layers one on each side the barrier layer, one polypropylene layer on one adhesive layer and two polypropylene layers on the other adhesive layer; and an eight layer structure that may include a barrier layer, two adhesive layers one on each side the barrier layer, three polypropylene layers on one adhesive layer and two polypropylene layers on the other adhesive layer.
• The multi-layer sheet structure may be used for forming various articles, for example, cups and cup shaped containers. The multi-layer sheet structure can be molded into various articles using methods known in the art including, for example, pressure forming, thermoforming, plug assisted thermoforming, thermal stamping, vacuum forming, compression forming, and the like. All the ingredients in the multi-layer sheet structure are FDA approved which permit the use of cups and cup shaped containers formed from the multi-layer sheet structure to come in contact with food and liquids for human consumption.
• Cup shaped containers may be formed using a plug assisted thermoforming process that utilizes cup shaped molds and plugs to assist the sheet structure into the mold and distribute the materials of multi-layer sheet structure around the mold to form a cup shaped container having a uniform wall, and uniform heel and the bottom area of the cup shaped container. The molds are designed to improve the material distribution around the cup shaped container wall, the heel area and the bottom area over known cup shaped containers. In addition, when the cup shaped container is used in a coffee brewing machine, the design of the mold and the distribution of the material of the multi-layer sheet structure in the bottom area permit clean punctures by the coffee brewing machine in the bottom area of the cup shaped container.
• Referring to the drawings,FIG. 1 is a cross sectional schematic illustration of an exemplary embodiment of amulti-layered sheet structure10 that includes seven layers. Specifically,multi-layer sheet structure10 includes an outer top layer12 (also referred to herein as first layer12) formed of a polypropylene composition, an inner top layer14 (also referred to herein as second layer14) formed of a polypropylene composition, a tie layer16 (also referred to herein as third layer16) formed of an adhesive material, a barrier layer18 (also referred to herein as fourth layer18), a tie layer20 (also referred to herein as fifth layer20) formed of an adhesive material, an inner bottom layer22 (also referred to herein as sixth layer22) formed of the polypropylene composition ofinner top layer14, and an outer bottom layer24 (also referred to herein as seventh layer24) formed of the polypropylene composition ofouter top layer12. The polypropylene composition ofouter top layer12 and the polypropylene composition ofinner top layer14 may be the same polypropylene composition, or different polypropylene compositions.
• The polypropylene composition offirst layer12 includes a polypropylene. The polypropylene may be at least one of a polypropylene homopolymer, polypropylene copolymer, and blends with polypropylene and compatible polymers. The polypropylene composition may also include a color concentrate and an inorganic reinforcing agent. The color concentrate may include color pigments and/or dyes dispersed in solvents and/or a polymer compatible with polypropylene. Any suitable inorganic reinforcing agent may be used, for example, talc, mica, glass, silica, whiskers, wollastonite, carbon fiber, aramid fibers, and the like. The polypropylene composition offirst layer12 may include about 2 to about 6 percent by weight of the color concentrate, about 50 to about 70 percent by weight of polypropylene, and about 5 to about 60 percent by weight of the inorganic reinforcing agent, the weight percent based on the total weight of the polypropylene composition. Alternatively, the polypropylene offirst layer12 may include about 4 percent by weight of the color concentrate, about 61 percent by weight of polypropylene, and about 35 percent by weight of the inorganic reinforcing agent, the weight percent based on the total weight of the polypropylene composition oflayer12.
• In another embodiment, the polypropylene composition offirst layer12 may also include a renewable plastics material or bioplastic, for example, a corn starch product. The corn starch product is a resin made from corn starch and referred to as Plastarch Material (PSM). Other bioplastics include, but not limited to, polylactic acid (PLA), modified PLA, polyhydroxyalkanoates (PHA), modified PHA, poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), and blends of these bioplastics with other plastics, for example polypropylene, polyethylene, and the like. In this embodiment, the polypropylene composition offirst layer12 may include about 2 to about 6 percent by weight of the color concentrate, about 5 to about 65 percent by weight of polypropylene, about 5 to about 75 percent by weight of the renewable plastics material, and about 10 to about 40 percent by weight of the inorganic reinforcing agent, the weight percent based on the total weight of the polypropylene composition. Alternatively, the polypropylene composition offirst layer12 may include about 4 percent by weight of the color concentrate, about 46 percent by weight of polypropylene, about 20 percent by weight of the renewable plastics material, and about 30 percent by weight of the inorganic reinforcing agent, the weight percent based on the total weight of the polypropylene composition. In another embodiment, the polypropylene composition offirst layer12 may be 100 percent by weight of polypropylene, and in another embodimentfirst layer12 may be 100 percent by weight of renewable plastics materials.
• In a further embodiment, the multi-layer sheets described above that were not used and left over after a thermoforming process may be recycled and added to a virgin polypropylene composition. Multi-layer sheets and/or portions of the sheets that are left over after a thermoforming process are ground-up and added to a virgin polypropylene composition. The ground-up recycled material includes each of the materials used to form each layer of the multi-layer sheets. The polypropylene composition offirst layer12 may include up to about 50 percent of the recycled material. The use of recycled material facilitates producing economically viable products formed frommulti-layered sheet structure10.
• The polypropylene composition ofsecond layer14 may be any of the embodiments of the polypropylene composition offirst layer12 described above. The polypropylene composition offirst layer12 and the polypropylene composition ofsecond layer14 may be the same polypropylene composition, or may be different polypropylene compositions.
• The polypropylene composition ofsixth layer22 may be any of the embodiments of the polypropylene composition offirst layer12 described above, and the polypropylene composition ofseventh layer24 may be any of the embodiments of the polypropylene composition offirst layer12. The polypropylene composition ofsixth layer22 and the polypropylene composition ofseventh layer24 may be the same polypropylene composition, or may be different polypropylene compositions.
• Any of the polypropylene compositions described above may be prepared by melt compounding the components with equipment known in the art. The equipment may include continuous and batch mixers, for example, Farrel Continuous Mixers available from Farrel Corporation, Ansonia, Conn., Banbury® mixers available from Farrel Corporation, single screw extruders, multiple screw extruders, and the like. In addition, compounding and melt mixing of the components in a continuous fashion, in-line with the production of extrudedmulti-layer sheet structure10 may also be used.
• Third layer16 andfifth layer20 are tie or adhesive layers formed of an adhesive material. The adhesive material is used to bondsecond layer14 tofourth layer18, and to bondsixth layer22 tofourth layer18. Suitable adhesive material that may be used include, but not limited to, a maleic anhydride grafted polypropylene adhesive, a functionalized polyethylene, a functionalized polypropylene, for example, a copolymer with polypropylene, a polyamide, blends of polyethylene and polypropylene containing active groups capable of reacting with the material ofbarrier layer18.
• Fourth layer18 is a barrier layer and is formed by at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, cyclic olefin copolymers, and the like.Fourth layer18 may also include fillers, for example, active/passive scavengers, nanofillers including talc, glass, clay, silica, mica, and the like.
• Multi-layer sheet structure10 has a thickness of about 10 mil to about 135 mil. Alternatively,multi-layer sheet structure10 has a thickness of about 10 mil to about 100 mil. Alternatively,multi-layer sheet structure10 has a thickness of about 35 mil to about 60 mil.First layer12 has a thickness of about 0.5 mil to about 15 mil,second layer14 has a thickness of about 3.5 mil to about 77.5 mil,third layer16 has a thickness of about 0.5 mil to about 5 mil,fourth layer18 has a thickness of about 0.5 mil to about 5 mil,fifth layer20 has a thickness of about 0.5 mil to about 5 mil,sixth layer22 has a thickness of about 3.5 mil to about 77.5 mil, andseventh layer24 has a thickness of about 0.5 mil to about 15 mil.
• FIG. 2 is a cross sectional schematic illustration of an embodiment of amulti-layered sheet structure30 that includes five layers. Specifically,multi-layer sheet structure30 includes a top layer32 (also referred to herein as first layer32) formed of a polypropylene composition, a tie layer34 (also referred to herein as second layer34) formed of an adhesive material, a barrier layer36 (also referred to herein as third layer36), a tie layer38 (also referred to herein as fourth layer38) formed of an adhesive material, and a bottom layer40 (also referred to herein as fifth layer40) formed of a polypropylene composition.
• The polypropylene composition offirst layer32 may be any of the embodiments of the polypropylene composition offirst layer12 described above and shown inFIG. 1, and the polypropylene composition offifth layer40 may be any of the embodiments of the polypropylene composition offirst layer12 described above and shown inFIG. 1. The polypropylene composition offirst layer32 and the polypropylene composition offifth layer40 may be the same polypropylene composition, or may be different polypropylene compositions.
• Second layer36 andfourth layer38 are tie or adhesive layers formed of an adhesive material. The adhesive material is used to bondfirst layer32 tothird layer36, and to bondfifth layer40 tothird layer36. Suitable adhesive material that may be used include, but not limited to, a maleic anhydride grafted polypropylene adhesive, a functionalized polyethylene, a functionalized polypropylene, for example, a copolymer with polypropylene, polyamide, blends of polyethylene, and polypropylene containing active groups capable of reacting with the material of thethird layer36.
• Third layer36 is a barrier layer and is formed by at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, cyclic olefin copolymers, and the like.Third layer36 may also include fillers, for example, active/passive scavengers, nanofillers including talc, glass, clay, silica, mica, and the like.
• FIG. 3 is a cross sectional schematic illustration of an embodiment of amulti-layered sheet structure42 that includes three layers. Specifically,multi-layer sheet structure42 includes a top layer44 (also referred to herein as first layer44) formed of a polypropylene composition, a barrier layer46 (also referred to herein as second layer46), and a bottom layer48 (also referred to herein as third layer48) formed of a polypropylene composition.
• The polypropylene composition offirst layer44 may be any of the embodiments of the polypropylene composition offirst layer12 described above and shown inFIG. 1, and the polypropylene composition ofthird layer48 may be any of the embodiments of the polypropylene composition offirst layer12 described above and shown inFIG. 1. The polypropylene composition offirst layer44 and the polypropylene composition ofthird layer48 may be the same polypropylene composition, or may be different polypropylene compositions.
• Second layer46 is a barrier layer and is formed by at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, cyclic olefin copolymers, and the like.Second layer46 may also include fillers, for example, active/passive scavengers, nanofillers including talc, glass, clay, silica, mica, and the like.
• FIG. 4 is a cross sectional schematic illustration of an embodiment of amulti-layered sheet structure50 that includes two layers. Specifically,multi-layer sheet structure40 includes a top layer52 (also referred to herein as first layer52) formed of a polypropylene composition, and a bottom layer54 (also referred to herein as second layer54) formed of a polypropylene composition.
• The polypropylene composition offirst layer52 may be any of the embodiments of the polypropylene composition offirst layer12 described above and shown inFIG. 1, and the polypropylene composition ofthird layer54 may be any of the embodiments of the polypropylene composition offirst layer12 described above and shown inFIG. 1. The polypropylene composition offirst layer52 and the polypropylene composition ofsecond layer52 may be the same polypropylene composition, or may be different polypropylene compositions.
• Multi-layer sheet structure10 may be fabricated by a co-extrusion process. Specifically,multi-layer structure10 may be formed by co-extrudingfirst layer12,second layer14,third layer16,fourth layer18,fifth layer20,sixth layer22 andseventh layer24. A plurality of extruders are connected to a feed block that includes a die for extruding multiple layers at once. Three to nine extruders may be used, and the feed block connected to the extruders has a die for forming from 3 to 13 layers. At least one extruder may be used for each different material. In the exemplary embodiment, five extruders are used to feed the materials for each of the layers to the feed block to form the seven layers ofmulti-layer sheet structure10. In alternative embodiments, four extruders or six extruders may be used to feed the materials for each of the layers to the feed block to form the seven layers ofmulti-layer sheet structure10. Other co-extruding techniques can be used, for example, a multi-manifold die may be used instead of a feed block. In addition, groups of multiple layers may be co-extruded and then laminated together to formmulti-layer sheet structure10. For examplefirst layer12 andsecond layer14 are co-extruded to form a first sheet, and third, fourth, andfifth layers16,18, and20 are co-extruded separate from first andsecond layers12 and14 to form a second sheet. Also,sixth layer22 and seventh layer are co-extruded separate from first, second, third, fourth, andfifth layers12,14,16,18, and20 to form a third sheet. Then the three sheets are laminated to formmulti-layer structure10.
• In the exemplary embodiment,multi-layer sheet structure10 may be used for forming various articles, for example, cups and cup shaped containers. Specifically, cup shaped containers are formed using a plug assisted thermoforming process that utilizes cup shaped molds and plugs to assistsheet structure10 into the mold and distribute the materials of multi-layer sheet structure around the mold to form a cup shaped container having a uniform wall, and uniform heel and the bottom area of the cup shaped container.
• FIGS. 5-12 are schematic illustrations of various molds that may be used to mold articles, for example, cups and cup shaped containers frommulti-layer sheet structure10.Mold70, shown inFIGS. 5 and 6, includes a forminginsert72 and a formingbase74. Forminginsert72 includes amold cavity76 and abase cavity78 sized to receive formingbase74. Formingbase74 includes atop surface80 that provides the shape of the bottom of a cup being molded.Mold82, shown inFIGS. 7 and 8, includes a forminginsert84 and a forming base86. Forminginsert84 includes amold cavity88 and abase cavity90 sized to receive forming base86. Forming base86 includes atop surface92 that provides the shape of the bottom of a cup being molded.Mold94, shown inFIGS. 9 and 10, includes a forming insert96 and a formingbase98. Forminginsert98 includes amold cavity100 and abase cavity102 sized to receive formingbase98. Formingbase98 includes atop surface104 that provides the shape of the bottom of a cup being molded.Mold106, shown inFIGS. 11 and 12, includes a forminginsert108 and a formingbase110. Forminginsert108 includes amold cavity110 and abase cavity112 sized to receive formingbase110. In addition,mold cavity110 includes a plurality offlutes114 in awall116 ofmold cavity110. Formingbase110 includes atop surface118 that provides the shape of the bottom of a cup being molded.Molds70,82,94, and106 may be made from any suitable material, for example, steel, stainless steel, aluminum, and the like.
• FIGS. 13-15 are bottom perspective schematic illustrations of plugs that may be used with the molds shown inFIGS. 5-12. Plug120, shown inFIG. 13, includes asmooth bottom122. Plug124, shown inFIG. 14, includes raised and lower area of a bottom126 to assist in forming the bottom of the cup being formed. Plug128, shown inFIG. 15, includes raised and lower area of a bottom130 to assist in forming the bottom of the cup being formed.Plugs124 and128 work synergistically withmolds70,82,94, and106 to increase the cup heel thickness as compared to cups formed withplug120. The increased heel thickness provides for increased strength of the cup heel as compared to cups formed withplug120.Plugs120,124, and128 may be made from any suitable material, for example, steel, stainless steel, aluminum, and the like. In addition, plugs120,124, and128 may also include a plastic outer layer formed from, for example, an epoxy, a silicone, and the like.
• FIGS. 16-23 include a side schematic illustration and a bottom perspective schematic illustration of various cup designs formed frommulti-layer10. Each cup includes acup wall121, aheel123, and abottom area125.Cup131, shown inFIGS. 16 and 17, has an increasedstack ledge depth132 and a reducedheel corner radius134 compared to known cups.Cup131 may be formed inmold70 shown inFIGS. 5 and 6.Cup140, shown inFIGS. 18 and 19, has an increasedstack ledge depth142 and a reducedheel corner radius144 compared to known cups. In addition,cup140 includes an addedcenter radius146 for strength.Cup140 may be formed inmold82 shown inFIGS. 7 and 8.Cup150, shown inFIGS. 20 and 21, has an increasedstack ledge depth152 and a reducedheel corner radius154 compared to known cups. In addition,cup150 includes two added center radius forstrength156.Cup150 may be formed inmold94 shown inFIGS. 9 and 10.Cup160, shown inFIGS. 22 and 23 has an increasedstack ledge depth162 and areduced corner radius164 compared to known cups. In addition,cup160 includes addedflutes166 to abottom portion168 ofcup wall120 for strength.Cup160 may be formed inmold106 shown inFIGS. 11 and 12.
• This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims (43)

1. A multi-layer sheet structure comprising:

a barrier layer having a first side and a second side;

at least one thermoplastic layer on said first side of said barrier layer; and

at least one thermoplastic layer on said second side of said barrier layer.

2. The multi-layer sheet structure in accordance withclaim 1 wherein said at least one thermoplastic layer on said first side of said barrier layer comprises a first layer comprising a first polypropylene composition, and said at least one thermoplastic layer on said second side of said barrier layer comprises a second layer comprising a second polypropylene composition.

3. The multi-layer sheet structure in accordance withclaim 2 further comprising a first adhesive layer between said first side of said barrier layer and said first layer, and a second adhesive layer between said second side of said barrier layer and said second layer.

4. The multi-layer sheet structure in accordance withclaim 3 further comprising a third layer comprising a third polypropylene composition on said first layer.

5. The multi-layer sheet structure in accordance withclaim 4 further comprising a fourth layer comprising a fourth polypropylene composition on said second layer.

6. The multi-layer sheet structure in accordance withclaim 5 further comprising a fifth layer comprising a fifth polypropylene composition on said third layer.

7. The multi-layer sheet structure in accordance withclaim 6 further comprising a sixth layer comprising a sixth polypropylene composition on said fourth layer.

8. The multi-layer sheet structure in accordance withclaim 2 wherein said first and second polypropylene compositions comprise a polypropylene and optionally at least one of a color concentrate, an inorganic reinforcing agent, and a bioplastic material, said first polypropylene composition is the same as said second polypropylene composition, or different from each other.

9. The multi-layer sheet structure in accordance withclaim 2 wherein said first and second polypropylene compositions further comprise up to 50% of recycled material comprising unused reground multi-layer sheet structures.

10. The multi-layer sheet structure in accordance withclaim 8 wherein said bioplastic material comprises at least one of a resin made from corn starch, polylactic acid materials (PLA), polyhydroxyalkanoates materials (PHA), poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), and blends of said bioplastic materials at least one of polyethylene and polypropylene.

11. The multi-layer sheet structure in accordance withclaim 1 wherein said barrier layer comprises at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, and cyclic olefin copolymers.

12. The multi-layer sheet structure in accordance withclaim 11 wherein said barrier layer further comprises least one of active scavengers, passive scavengers, talc, glass, clay, silica, and mica.

13. The multi-layer sheet structure in accordance withclaim 1 wherein said multi-layer sheet structure does not include said barrier layer.

14. A multi-layer sheet structure comprising:

a barrier layer having a first side and a second side;

a first adhesive layer on said first side of said barrier layer;

a second adhesive layer on said second side of said barrier layer;

a first layer on said first adhesive layer, said first layer comprising a first polypropylene composition; and

a second layer on said second adhesive layer, said second layer comprising a second polypropylene composition.

15. The multi-layer sheet structure in accordance withclaim 14 wherein said first layer comprises a plurality of first thermoplastic layers, each of said plurality of first thermoplastic layers comprising a polypropylene composition.

16. The multi-layer sheet structure in accordance withclaim 15 wherein said second layer comprises a plurality of second thermoplastic layers, each of said plurality of second thermoplastic layers comprising a polypropylene composition.

17. The multi-layer sheet structure in accordance withclaim 14 wherein said first and second polypropylene compositions comprise a polypropylene and optionally at least one of a color concentrate, an inorganic reinforcing agent, and a bioplastic material, said first polypropylene composition is the same as said second polypropylene composition, or different from each other.

18. The multi-layer sheet structure in accordance withclaim 17 wherein said first and second polypropylene compositions further comprise up to 50% of recycled material comprising unused reground multi-layer sheet structures.

19. The multi-layer sheet structure in accordance withclaim 17 wherein said bioplastic material comprises at least one of polylactic acid materials (PLA), polyhydroxyalkanoates materials (PHA), poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), a resin made from corn starch, and blends of the bioplastic materials with at least one of polyethylene and polypropylene.

20. The multi-layer sheet structure in accordance withclaim 14 wherein said barrier layer comprises at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, and cyclic olefin copolymers.

21. A method of making a multi-layer sheet structure, said method comprising:

connecting a plurality of extruders to a die configured to extrude a plurality of layers;

feeding a plurality of thermoplastic materials to the plurality of extruders; and

co-extruding a plurality of layers from the plurality of thermoplastic materials to form the multi-layer sheet structure, the plurality of layers comprise:

a barrier layer having a first side and a second side;

at least one thermoplastic layer on the first side of the barrier layer; and

at least one thermoplastic layer on the second side of the barrier layer.

22. The method in accordance withclaim 21 wherein connecting a plurality of extruders to a die comprises connecting the plurality of extruders to a feed block having a die configured to extrude a plurality of layers.

23. The method in accordance withclaim 21 wherein connecting a plurality of extruders to a die comprises connecting the plurality of extruders to a multi-manifold die configured to extrude a plurality of layers.

24. The method in accordance withclaim 21 wherein co-extruding a plurality of layers comprise co-extruding:

a barrier layer having a first side and a second side;

at least one thermoplastic layer covering the first side of the barrier layer; and

at least one thermoplastic layer covering the second side of the barrier layer.

25. The method in accordance withclaim 24 wherein co-extruding comprises co-extruding:

a barrier layer;

a first layer onto the first side of the first side of the barrier layer, the first layer comprising a first polypropylene composition; and

a second layer onto the second side of the barrier layer, the second layer comprising a second polypropylene composition.

26. The method in accordance withclaim 25 wherein co-extruding further comprises co-extruding:

a first adhesive layer between the first side of the barrier layer and the first layer; and

a second adhesive layer between the second side of the barrier layer and the second layer.

27. The method in accordance withclaim 26 wherein co-extruding further comprises co-extruding:

at least one layer onto the first layer, the at least one layer comprising a third polypropylene composition.

28. The method in accordance withclaim 27 wherein co-extruding further comprises co-extruding:

at least one layer onto the second layer, the at least one layer comprising a fourth polypropylene composition.

29. The method in accordance withclaim 27 wherein co-extruding further comprises co-extruding:

co-extruding a first group of layers;

co-extruding a second group of layer; and

laminating the first group of layers to the second group of layers.

30. The method in accordance withclaim 25 wherein the first and second polypropylene compositions comprise a polypropylene and optionally at least one of a color concentrate, an inorganic reinforcing agent, and a bioplastic material, the first polypropylene composition is the same as the second polypropylene composition, or different from the second polypropylene.

31. The method accordance withclaim 25 wherein the first and second polypropylene compositions further comprise up to 50% of recycled material comprising unused reground multi-layer sheet structures.

32. The method in accordance withclaim 30 wherein the bioplastic material comprises at least one of polylactic acid materials (PLA), polyhydroxyalkanoates materials (PHA), poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), a resin made from corn starch, and blends of the bioplastic materials with at least one of polyethylene and polypropylene.

33. The method in accordance withclaim 21 wherein the barrier layer comprises at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, and cyclic olefin copolymers.

34. A multi-layer sheet structure comprising:

a first layer; and

a second layer;

said first layer comprise a first polypropylene composition and said second layer comprise a second polypropylene composition.

35. The multi-layer sheet structure in accordance withclaim 34 further comprising a barrier layer positioned between said first layer and said second layer.

36. The multi-layer sheet structure in accordance withclaim 35 further comprising:

a first adhesive layer positioned between said barrier layer and said first layer; and

a second adhesive layer positioned between said barrier layer and said second layer.

37. The multi-layer sheet structure in accordance withclaim 36 further comprising at least one cap layer positioned on said first layer, said at least one cap layer comprising a third polypropylene composition.

38. The multi-layer sheet structure in accordance withclaim 37 further comprising at least one cap layer positioned on said second layer, said at least one cap layer comprising a fourth polypropylene composition.

39. The multi-layer sheet structure in accordance withclaim 34 wherein said first and second polypropylene compositions comprise a polypropylene and optionally at least one of a color concentrate, an inorganic reinforcing agent, and a bioplastic material, said first polypropylene composition is the same as said second polypropylene composition, or different from said second polypropylene composition.

40. The multi-layer sheet structure in accordance withclaim 34 wherein said first and second polypropylene compositions further comprise up to 50% of recycled material comprising unused reground multi-layer sheet structures.

41. The multi-layer sheet structure in accordance withclaim 39 wherein said bioplastic material comprises at least one of a resin made from corn starch, polylactic acid materials (PLA), polyhydroxyalkanoates materials (PHA), poly(hydroxybutyrate-co-valerate) (PHBV), poly(hydroxubutyrate-co-hexanoate) (PHBH), and blends of said bioplastic materials at least one of polyethylene and polypropylene.

42. The multi-layer sheet structure in accordance withclaim 35 wherein said barrier layer comprises at least one of poly(ethylene vinyl alcohol) (EVOH), polyvinyl alcohol (PVOH), polyvinylidene chloride (PVDC), polyamide, acrylate copolymers, and cyclic olefin copolymers.

43. The multi-layer sheet structure in accordance withclaim 42 wherein said barrier layer further comprises least one of active scavengers, passive scavengers, talc, glass, clay, silica, and mica.

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