Title of Invention

ESCAPSULATED BARRIER FOR FLEXIBLE FILMS AND A METHOD OF MAKING THE SAME.

Abstract

TITLE: ENCAPSULATED BARRIER FOR FLEXIBLE FILMS AND A METHOD OF MAKING THE SAME. Coextruted films having a heat a sensitive barrier layer comprising materials such as EV011, nylon etc, which has been encapsulated by a first adhesive material, and additional adhesive layers of a higher melting polymer deposited on the first adhesive layer. The first adhesive layers help to protect the heat sensitive barrier material from the heat of extrusion/lamination.

Full Text

Encapsulated Barrier for Flexible Films And a Mitood of Making the Same The present invention relates to an encapsulated banter film structure and a method of malting the same. More specifically, the present invention relates to a thermoplastic, multilayer packing film having a barrier layer consisting of a thermally sensitive polymer material, preferably ethylene vinyl alcohol. The material acts to prevent the passage of gases such as, for example, oxygen and/or water vapor, from one side of the film to the other. The barrier material is encapsulated by one or more layers of a relatively thermacy stable material that acts to protect the barrier material from high temperatures and/or long residence times present during coextrusion, lamination or coating mat may destroy or otherwise degrade the barrier material. The one or more thermally stable encapsulsting layers and in bindmg the thermally sensitive barrier layer to outer layers having relatively higher melt and/or extrusion temperatures thereby maintaining optical clarity of the film produced therefrom, In addition, the present invention relates to using an acid terpolymer as an adhesive to bind the thermally sensitive barrier cose material to high temperature outer layers white eliminating clarity problems associated with using other adhesives. It is, of course, generally known to utilize a polymeric material as % barrier material in films to prevent the passage of molecules such as, for example, gases and water vapor. Films may have these barrier properties to protect foods or other gas-sensitive materials that may be contained within bags or other containers made from the films. In particular, food articles are subject to the deleterious effects of gases and water vapors. A known film structure that prevents the passage of molecules therethrough uses polyvinylidene chloride ("PVdC) or polyvinylidene chloride/methyl acrylate copolymer ("PVdC/MA"), commonly known as MA-Saran and manufactured by Dow Chemical Company. These barriers are generally useful in preventing molecules suck as oxygen from patting therethrough but are fastly unstable at the high temperatures needed to produce many multilayer films from a moltes, resin. Typically, FVdC degxades at high temperatures forming polyenes reducing the optical clarity of films made therefrom. A suitable, albeit more costly, substitute for MA-Saran is emylene vinyl alcohol coporymer ("EVOH"). Another film that ia commonly used as a barrier layer, especially for food products such aa cheese, is a PVdC coated oriented polypropylene ("OPP") layer. Structures made using this barrier material have good barrier characteristics. Specifically, barrier layers of FVdC coated OFF adequately restrict the movement of oxygen molecules or water vapor through packaging made therefrom. However, PVdC coaled OPP is coat prohibitive. Generally, EVOH ia thermally stable at higher temperatures relative to PVdC or MA-Saran. However, EVOH is still sensitive to high temperature, particularly when adhered to a layer of polyethylene ("PE") having maleic anhydride functional groups. While EVOH may be extruded at higher temperatures relative to PVdC, the temperature of extrusion may still be too low for coextrusion win other layers mat require very high temperatures for adequate melting and/or adhesion to lamination or coating substrates. Typical methods of coextrusion generally entail feeding the barrier material and adhesive resins into a feedblock where they are arranged into an "A/B/A" configuration prior to extrusion through a die. The adhesive layers most be compatible with me barrier layer as well as me substrates that are being laminated or coated. Further, the adhesive layers most be at or greater man 600°F to adequately adhere to the substrace. However, this adhesive layer melt temperature requites mat the downstream hardware (such as, for example, the feedblock and/or the die) be at or greater man 600°P as well. Many barrier materiala, including, especially, EVOH, ready degrade when exposed to tomperatures greater than about 450oF for extended periods of time. Dae to mis degradation, as well as me extensive reaction mat may occur between the barrier material and the adhesive layer at the layer interface, the ratting extrudate may have clarity or other problems. For example, BVOH reacts wife boiled amhydride, a typical adhesive layer wed with BVOH, to produce a "ground glass" appearance when coextraded at high temperatures for extended periods of time. A known process of coextruding and laminating heat sensitive materials is described fat U.S. Patent Nor 5,106,562, 5,108,844, 5,190,711 and 5,236,642, which are hereby incorporated by reference in their entirety. Various methods are disclosed fot reducing the impact of higher temperature polymeric meltstream elements on a lower temperature polymeric meltstream. The methods may include super-cooling the hotter meltstream element below me melting temperature hot above the crystallization (empertture, exposing one or more moltstream elements to an another thermal condition for a limited period of time, and/or using one or more layers as a heat sink via encapsulation. Specifically, these patents describe methods of encapsulating one film layer by another material. The "562 and "844 patents specifically relate to FVdC or, preferably, PVdC-MA core materials with othylene vinyl acetate copolymer ("EVA") or emylene methyl acrylete copolymer ("EMA") or blend"s thereof encapsulating me core material The encapsulated PVdC or PVdC-MA is, therefore, protected from the high temperature of the coextrusion process. Generally, the encapsulation memod uses am encapsalator having a crosshead mandrel with a central bore to receive a first mettstream element from an extruder. A second polymeric meltstream is fed through a sleeve via an inlet passage into me oncapsalator. As me second meltsteam enters the encapsulator, it splits and flows around me first meltstream. Consequently, the second meltstream completely surrounds me first meltstream, thereby forming a combined meltsteam. The second meltstream forms a contimuous layer about the circumference of the first meltstream completely surounding me first mettstream. Thus, me first and second ineltstreams maintain their individual identities while me first meltstream is completely surrounded by and encapsulated within the second meltsteam. The combined meltstream may men be fed through a transport pipe to a feedblock for coextrusion with one or more other layers to produce a meltilayer film. However, these patents do not disclose other material that may be utilized as heat sensitive barrier materials besides PVdC or PVdC-MA Summary of the Invention The present invention relates to encapsulating a barrier material with a flat adhesive layer at the same melt temperature as the barrier material. For example, EVOH melts at less than 450°F and, therefore, is encapsulated by the first adhesive layer at less than 450oF prior to entering the feedblock. The eacapsulating first adhesive layer protects the barrier material from the hot melt temperatures of a. second adhesive layer, which the first adhesive material encounters within the feedblock. The first adhesive material insulates the barrier material from the month higher melt temperature of the second adhesive layer. Moreover, the first adhesive material directically reduces the residence time of the barrier material within the hardware by keeping it away from areas of high drag and hangup, such as the internal walls of the hardware. The result is an extradite with excellent clarity. It is, therefore, an advantage of the present invention to provide a film structure and a method of manufacturing me same mat use a relatively inexpensive barrier material to prevent the nalgration of gases through the film structnre such as, for example, oxygen and/or water vapor, without degrading due to high heat and/or long residence times within the film producing equipment. The encapsulated EVOH barrier layer may be utilized effectively as. a replacement to oost-prohibitive barrier materials such, as PVdC coated OPP. Another advantage of the present invention is to provide a film structure and a method of manufacturing the same that allow the use of a thermally sensitive barrier material to be utilized within high temperature coextrusion/lamination process. And, an advantage of me present invention is to provide a fihn structure and a method of manufacturing the same mat surround the thermally sensitive barrier material with an adhesive in an encapsulating process to protect the barrier material from high temperature that may exist in the coextrusion/lamination process. A still further advantage of the present invention is to provide a film structure and a method of manufacturing the same that use an adhesive to encapsulate the barrier material at the melt temperature of the barrier material. Further, the adhesive layer may protect the barrier material from layers coextruded therewith or laminated thereto having higher melt temperatures. In addition, the adhesive may protect the barrier material from high temperatures of the hardware and long residence times within the hardware. Moreover, an advantage of the present invention is to provide a film structure and a method of manufacturing the same that uses a thermally sensitive material such as EVOH as the barrier layer material to reduce costs of the film structure. And, another advantage of the present invention is to provide a film structure and a method of manufacturing the same that eliminates interlayer leakage and deadspots in the barrier layer material flow patterns. Additional features and advantages of the present invention are described in, and will be apparent from, the detailed description of the presently preferred embodiments and from the drawings. Brief Description of the Accompanying Drawings Figure 1 illustrates an improved-coextrusion lamination process having a plurality of extruders and encapsulators in an embodiment of the present invention. Figure 2A shows a film structure having a barrier layer encapsulated by first adhesive layers which, in turn, are encapsulated by second adhesive layers, and then laminated outer substrates in an embodiment of the present invention. Figure 2B illustrates a film structure having a barrier layer encapsulated by first adhesive layers and coextruded with second and third adhesive layers. Further, outer substrate layers are then laminated thereto. Figure 2C illustrates an alternate embodiment of the present invention of a barrier layer encapsulated by first adhesive layers and coextruded with a single second adhesive layer on only one side of the barrier layer/first adhesive layer encapsulation. Further, outer substrate layers are then laminated thereto. Detailed Description of the Presently Preferred Embodiment The protect invention relates to a film structure and a method of manufacturing the film structure. Mote specifically, the present invention relates to a structure having a banter layer to protect against the migration of molcules such at, for example, gates and/or water vapors. Generally, a first adhesive layer at a relatively low melt temperature encapsulates a thermally sensitive barrier layer. Other adhesive layers are extraded at high temperatures relative to the barrier layer and encapsulate or otherwise are coextruded with the first adhesive tayer and the barrier layer. The high temperature of the second adhesive layers aid in adhering the other adhesive layers so outer substrate layers. The first adhesive layers may thereby act as both a heat sink to protect the barrier layer from the high temperature of the coextrusion/lamination process and a the layer to aid in bonding the thermally sensitive harder layer to the outer substrate tayers. Moreover, the present invention, relates to an improved adhesive layer comprising an acid terpolymer for EVOH that may be used in any high temperature coextrusion process. Referring now to the drawings wherein like numerals refer to like parts, Figure 1 illustrates an encapsulation system 1. The encapsulation system 1 may include an extruder 3 mat may melt and extrude a barrier material 2 into a meltstream 4 using means well known in the art. The barrier material 2 may be melted and extruded at a relatively low temperature so mat the barrier material 2 does not degrade within the extruder 3. An adhesive material 10 may be extruded in a second extruder 9 to form in adhesive meltstream 8. The adhesive material 10 may be melted and extruded at a temperature that is the same or relatively similar to the melt temperature of the barrier material 2. The meltstream 4 may then be fed into an encapsulator 6 and encapsulated by the adhesive material 10 via methods described in U.S. Patent Nos. 5,106.562, 5,108.844. 3,190,711 and 3,236.642, each of which is incorporated in these entirety by reference. By encapsulating the thermally sensitive barrier material 2 (meltstream 4) by the adhesive material (meltstream 8), the barrier material 2 may be protected from high temperatures present within the system 1. Further, the adhesive material 10 (meltstream 8) may aid in reducing the residence time of the barrier material 2 within the downstream coextrusion hardware. The residence time is reduced because me encapsulating adhesive material 10 increases the laminar from of the barrier material 2 through the hardware. In other words, the barrier material 2 will not get held up on the surfaces of the downstream hardware since the barrier material 2 will not contact me surfaces of the hardware. An encapsulated meltstream 12 is thereby produced that may then fed into a feedblock 14. The feedblock 14 may be a Clorren feedblock, or any other feedblock apparent to those skilled in the art. At this point, a number of different options are available to create a number of different structures. First, the encapsulated meltstream 12 may be encapsulated by a meltstream 16 from a second adhesive material 18 that is method and extruded in a third extender 15. Partial cancapsulation may occur if the encapsulating material does not completely surround the encapsulated material. Second, the meltstream 16 and a meltstraeam 17 from a third adhesive material 20 mat is melted and extruded in a fourth extruder 19, may be coextruded with the encapsulated meltstream 12 within the feedblock 14. A multylayer-coextruded sheet 22 may be formed after passing the meltstream through a die 21 to thin and spread the material into the flat sheet 22. After the sheet 22 is produced, it may be laminated with outer layers such as various substrates detailed below with reference to Figures 2A-2C. Figure 2A shows an improved structure 100 that may be produced by the system described above with reference to Figure 1. The structure 100 may include a barrier layer 110 mat may be completely encapsulated by first adhesive layers 112. The barrier layer 110 may be composed of any thermoplastic polymeric material mat may prevent me migration of molecoles sach as, for example, oxygen and water vapor, thereby protecting sensitive materials contained within packages made from the structure 100. For example, the structure 100 may be utilized as a bag mat may be sealed on all sides and may completely surround an article of food contained therein. The barrier layer 110 may preferably be made from a material having superior barrier properties such as, for example, polymers and/or copolymers of HVOH and EVOH blends of nylon or polyethylene. Moreover, other materials may include polyamide polymers, copolymers and blends thereof; PVdC and PVdC-MA; acrylonitrile polymers and copolymers; and polyethylene copolymers and/or blends. The barrier layer 110 may be protected by the first adhesive layer 112 that may encapsulate the barrier layer 110 via the system described in Figure 1. The first adhesive layers 112 may be coextruded to encapsulate the barrier layer 110 to create a first encapsulated extrudate 113 composed of a barrier layer 110 completely surrounded by first adhesive layers 112. The first extrudate 113 may then be coemtruded with and/or encapsulated by second adhesive layers 114 at a higher temperature than the first encapsulated extrudate 113. The first adhesive layers 112 may product the barrier layer 110 from the high temperatures necessary to adequstely melt and extrude the second adhesive layers 114 or any other layer coextruded, laminated or otherwise disposed adjacent to the first adhesive layers 112. Outer layers 116, 118, and/or 120 may be laminated to the first extrudate 113 as apparent to those skilled in the art. The owner layers 116,118 and/or 120 may include any substrate necessary to add desired properties to the structure 100. For example, the outer layer 116 may include any material that may add strength, stiffness, heat resistance, durability and/or printability to the structure 100. Further, the layer 116 may act to prevent the migration of certain types of molecules, such as, for example, modulate, from penetrating into the inner layer of the structure 100. Further, the layer 116 may add flex crack resistance to the film structure produced. In addition, the outer layer 120 may be composed of a material that may act as s sealant when heated. However, it ahoald be noted mat the outer layers 116,118 and/or 120 may be composed of any material apparent to those skilled in the act for providing desired characteristics to the structure 100. Alternatively, the first extradate 113 may be coextruded with one or more layers as shown with reference to Figures 2B and 2C, rather than be encapsulated with the adhesive layers 114. Referring now to Figure 2B, the first extrudate 113 may be coextruded with an adhesive layer 130 on a surface of the first extrudate 113. Another adhesive layer 132 may be coextrnded on an opposite surface of the first extradate 113. The adhesive layer 130,132 may be the same notarial or, alternatively, may be composed of different materials. The adhesive layers 130,132 may be different depending on the type of material bonded thereto to from the outside layers 116, 118 and/or 120. However, any type of layer may be laminated thereon as may be apparent to those skilled in the art. Further, the first extradate 113, including the barrier layer 110 and the first adhesive layers 112, may have an adhesive layer 134 coextruded on only one surface of the first extrudate 113 as shown in Figure 2C. In addition, there may be no adhesive layer disposed on the opposite surface of me tost extradase 113. Further, the outer layers 116,118 may be laminated to the adhesive layer 134. Conventional adhesive layers coextnided, laminated or otherwiae disposed adjacent to an EVOH barrier layer typically are compoaed of a ream of polyethylene haying maleic anhydride grafted thereon. However, as stated previously, maleic anhydride tends to react with the EVOH copylyner chain causing crosslinkages between the maleic enhydride grafted polyethylene and the EVOH. Many crosspackages may degrade me qnalny of the barrier layer properties and may father degrade the optical clarity of the film, causing a wavy "ground glass" appearance. Therefore, other material may be utilized in the present invention as adhesive layers to encapsulate, coextrude with, laminate to or otherwise be disposed adjacent to the EVOH barrier material. For example, it has been determined that an acid terpolymer of, prederably, ethylese, acrylic acid and methyl acrylate works well to tie the barrier layer of EVOH to outer layers of the film structure while protecting the EVOH barrier layer from Ugh temperatures and long residence times within the coextrusion hardware. Moreover, acid terpolymer may be used as an adhesive layer for the following barrier layers: EVOH; EVOH/nylon blends; EVOH/polyethylene ("PE") copolymers; polyaamides and acrylonitrile. Although acid terpolymer may not bind well with EVOH, this invention allows the EVOH and acid terpolymer to be subject to long residence times in order to adequentely adhere to each other. Further, polyamide, otherwise known as nylon, also may adequestely bond BVOH to outer substrate layers. Polyamide adhesive layers may adhere to the following barrier layers at relatively low melt temperatures: EVOH, EVOH/nylon blends, EVOH/PE copolymers and polyamide. Moreover, acid terpolymers and nylon may provide good adhesiom to EVOH without causing the optical clarity problems associated with maleic adhydride. It should also be noted that white acid terpolymer and nylon may be used wife encapsulation, at described above, they should not be limited in that regard. Specifically, acid terpolymer and nylon adhesive layers adhering to EVOH may be used in any film-making process apparent to those skilled in the art, including coextrusion and lamination processes. Moreover, although maleic anhydride grafted to PB may canae clarity problems when used as an adnealve with EVOH, maleic anhydride may still be used, especially when clarity it not an issue. Polyethylene grafted with maleic anhydride fractional groups may bond to the following barrier layers: EVOH, EVOH/nylon blends, EVOH/PE copolymers, polymides and PVdC-MA. Oner adhesive layers that may be utilized to bond to the barrier layer and to the barrier layers to outer layers may include a polystyrene block copolymer, preferably for bonding to an acrylonitrile barrier layer. In addition, ethylene acrytic add copoiymer ("BAA") may be need to bond to PVdC-MA or an acrylonitrile barrier layer. The adhesive layers 114, 130, 132 and/or 134 as shown in Figaros 2A-2C may aid in bonding me adhesive layen 112 to substrates mat may be disposed on outside surfaces of me film structure. Generally, the adhesive layers 114,130,132 and/or 134 may be meted and/or coextruded at relatively high temperatures since the adheaive layen 112 protect the barrier layer 110. The fact that EVOH is protected by the adheaive layers 112 allows me use of high temperature to adequentely adhere the adhesive layers 114, 130, 132 and/or 134 to the outer substrate layers. The adhesive layers 114, 130, 132 and/or 134 may comprise any of the following: acid terpolymer; maleic antydride grafted to polyethylene; EMA; EVA; or polystyrene block copolymer. Further, EMA may be used to the adhesive layers 112 to the following outer layers: oriented polyesters; oriented polypropylene; oriented nylon, metal foil; paper and paper board. further, EVA may be used as the adhesive layers 114, 130, 132 and/or 134 to bond the adhesive layers 112 to oriented polyesters, metal foil, uniaxially oriented polypropylene or high density polyethylene ("HDPE"), paper and paper board. Finally, polyethylene such as low density polyethylene ("LDPE"), linear low density polyethylene ("LLDPE"), medium density polyethylene ("MDPE") and HDPE may be med as the adhesive layers 114, 130, 132 and/or 134 to the adhesive layers 112 to many other types of layers except biaxially oriented polypropylene, uniaxially oriented polypropylene or HDPE. The barrier layer 110, adhesive layers 112, 114, 130, 132 tad/or 134 may be laminated to substrates to form completed film structures. As noted with reference to Figures 2A and 2B, the substrates may include the owner layers 116, 118 and/or 120. The substrates may be composed of any of the following materials; oroented polyesters and variations thereof including metalized polyesters; oriented polypropylene and variations thereof including matalized PP; biaxcially oriented nylon; metal foil; unusually oriented PP or HDPE; paper and paper board; non- oriented nylon or EVOH/nylon blends, including metallized variations thereof; extrusion coated PET/nylon; single site catalyzed ("SSC") polyolefins and iosomers. It should be noted that the list of substrates above is not exhaustive; any polymeric material may be need as a substrate for any purpose as may be apparent to those skilled in the art. The following table lists common substrates with materials commonly used as adhesives. Further, the table lists the melt temperatures necessary to adequetely adhere the adhesive materials to the substrates: As shown in Structure 1 and corresponding to the film structure shown in Figure 2A or 2B, EVOH or an EVOH blend (>75% BVOH) may be used as the barrier layer 110 with acid terpolymer or maleic anhydride grafted to PE as the adhesive layers 112 encapasulating fee EVOH barrier layer 110. In a preferred embodiment, the EVOH barrier layer may be encapsulated by add terpolymer forming the first extnidate 113 at a first temperature that is relatively low since both the EVOH and acid terpolymer will extrude within the same temperature range of 400° F and 450° F, preferably 410° F. Next, PB copolymers or blends thereof may be coextruded with the first extrudate 113 of EVOH and acid terpolymer or maleic anhydride to make a film, structure corresponding to the film structure of Figure 2B. Alternatively, the first extradate 113 may be fed through a second encapsulator thereby encapsulating the first extrudate by the PE copolymer such as, for example, EMA, thereby making a film structure corresponding to me film structure of Figure 2A. Preferably, the adhesive layers 114, 130 are EMA. To adequately adhere the EMA to me oriented polypropylene layer, as shown in Structure 1, me EMA should be extruded at a temperature of about 550° F. Moreover, the adhesive layers 114, 132 bonded to the outer layer 120 of PET should be extruded at a temperature of about 610° F to adequately adhere to the PET. As previously noted, the adhesive layers 112 protect the EVOH barrier layer from the high temperatures or long residence times of the encapsulation or coextrusion of the adhesive layers 114,130 and/or 132. As shown in Structure 2 and corresponding to the Him structure shown in Figure 2A or 2B, EVOH or an EVOH Mend (>75% EVOH) may be used as the barrier layer 110 with nylon as the adhesive layers 112 encapsulating the EVOH barrier layer 110. The EVOH barrier layer may be extruded within a temperature range of 400o F and 450° F, preferably 410° F and may be encapsulated by nylon that may be extruded within the temperature range of 440° F and 470° F, preferably 450° F. Next, the adhesive layers 114,130 and/or 132 comprising a layer of LDPE or EMA may encapsulate or otherwise be coextruded with the first extradate 113 of EVOH and nylon to make a film structure corresponding to the film structure of Figure 2A or 2B. To adequately adhere the LDPE or EMA to the oriented polypropylene layer, as shown in Structure 2, the LDPE or EMA should be extracted at temperature of about 550° F. Moreover, the adhesive layers 114,132 comprising LDPE or EMA bonded to the outer layer 120 of PET should be extruded at a tenperatnre of about 610° F to adequately adhere to the PET. As previously noted, the adhesive layers 112 protect the EVOH barrier layer from the high temperatures or long residence times of the encapsulation or coextration of the adhesive layers 114,130 and/of 132. Structure 3 may correspond to the fin structure of Figure 2B, except without the outer layer 116. In other words, Structure 3 may nave a barrier layer 110 of EVOH encapsulated by the adhesive layers 112 comprising, preferably, acid terpolymer. Again, the EVOH and the acid terpolymer may be extruded between 400° F and 450° F. Adhesive layer 114, 130 and/or 132 may encapsulate or otherwise be coextruded with the first extrudate 113 comprising EVOH and acid terpolymer. The adhesive layers 114, 130 bonding to outer layer 118 comprising EVA may be extruded at a temperature between 580° F and 620o F. The adhesive layers 114,132 that bond to the outer layer 120 comprising PET may be extruded at a temperature of about 610° F. The elimination of the OPP layers allows for the use of LDPE as the adhesive layer 114 or 130. Structure 4 illustrates another preferred embodiment of the present invention. In this embodiment, the barrier layer 110 may be EVOH or EVOH blended with nylon, having adhesive 112 couprising nylon encapsulating the barrier layer 110. Again, the barrier layer 110 and the first adhesive layer 112 my be extruded and encapsulated at roughly the same temperature to protect the barrier layer from degradation caused by baat or long residence times. Further, the adhesive layers 114, 130 and/or 132 may comprise polyethylene blended with polyethylene having maleic anhydride functional groups grafted thereto and may encapsulate the barrier layer and the first adhesive layers or may otherwise be coemtraded therewith. The adhesive layers 114, 130 and/or 132 may be extruded at a relatively high temperature compared to the barrier layer and the adhesive layers 112: about 580° F to about 620o F. The outer layer 116 may comprise an oriented polypropylene layer or a layer of nylon disposed between the adhesive layer 114 or 130 and the outer layer 118 may comprise a sealant layer of EVA or other material. Further, the outer layer 120 may be PET or biaxially oriented nylon. Another embodiment may have no outer layer 116 disposed between me adhesive 114 or 130 and the outer layer 118. It should be understood that various changes and modification to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages, It is, therefore, intended that such changes and modifications be covered by the appended claims. We Claim: 1. A film structure comprising: a thermally sensitive barrier layer made from a first polymeric material having a melt temperature range between about 400° F and about 450° F; a first set of adhesive layers disposed on opposite surfaces of the barrier layer wherein the first adhesive layers are made from a second polymeric material having a melt temperature between about 400° F and about 450° F, wherein said first set of adhesive layers are formed by encapsulating said barrier layer with said second polymeric material; a second set of adhesive layers on an outside surface of the first adhesive layers having a melt temperature between about 550° F and about 620° F, wherein said barrier layer and first and second set of adhesive layers are co-extruded to form an extrudate; and at least one substrate layer formed separately from and adhered to said extrudate. 2. The film structure as claimed in claim 1 wherein the barrier layer is made of a material comprising ethylene vinyl alcohol. 3. The film structure as claimed in claim 1 wherein the barrier layer is made of a material selected from the group consisting of ethylene vinyl alcohol copolymer; ethylene vinyl alcohol copolymer blended with polyamide; ethylene vinyl alcohol copolymer blended with polyethylene; polyamide; polyvinylidene chloride copolymer and acrylonitrile. 4. The film structure as claimed in claim 1 wherein said first set of adhesive layers is made from a polymeric material selected from the group consisting of an acid terpolymer, polyamide, polyolefin copolymer having maleic anhydride grafted thereto, ethylene methyl acrylate copolymer, ethylene vinyl acetate copolymer, polystyrene block copolymer, and ethylene acrylic acid copolymer. 5. The film structure as claimed in claim 1 wherein said second set of adhesive layers is made from a polymeric material selected from the group consisting of polyethylene, polyethylene copolymer and polyethylene copolymer having maleic anhydride grafted thereto. 6. The film structure as claimed in claim I comprising: a sealant layer forming an outside layer of the film structure disposed adjacent to an outside surface of the substrate; and an outside layer of the film structure disposed on an opposite side of the film structure from the sealant layer. 7. The film structure as claimed in claim 1 wherein said substrate comprises oriented polypropylene and wherein the film structure comprises: a sealant layer forming a first outside layer of the film structure disposed adjacent to the polypropylene layer; and a second outside layer of the film structure disposed on an opposite side of the film structure from the sealant layer. 8. The film structure as claimed in claims 6 or 7 wherein the outer layer is made from a polyester or biaxially oriented nylon. 9. The film structure as claimed in claims 6 or 7 wherein the sealant layer comprises a material selected from the group consisting of ethylene vinyl acetate copolymer, single site catalyzed polyolefin, polyethylene, an ionomer and polypropylene. 10. A film structure comprising: a barrier layer made from ethylene vinyl alcohol; a first adhesive material wherein the thermally sensitive material is encapsulated by the first adhesive material forming a first extrudate upon co-extrusion of the thermally sensitive material and the first adhesive material at a first temperature wherein the first adhesive material forms first and second adhesive layers on opposite sides of the barrier layer; and a second adhesive material adhered to the first extrudate on a surface of the first extrudate wherein the second adhesive material forms a third adhesive layer on at least one outside surface of the first adhesive material wherein the second adhesive material is coextruded with the first extrudate at a second temperature to form a second extrudate wherein the second temperature is higher than the first temperature; and at least one substrate formed separately from and adhered to an outside surface of the second extrudate. 11. The film structure as claimed in claim 10 wherein the barrier layer and the first adhesive material are extruded at a temperature between about 400° F and 450° F and wherein the second adhesive material is extruded at a temperature of between about 550° F and 620° F. 12. The film structure as claimed in claim 10 comprising: an outer layer laminated to each outside surface of the second extrudate. 13. The film structure as claimed in claim 10 comprising: a third adhesive material forming a fourth adhesive layer on another outside surface of the first extrudate. 14. The film structure as claimed in claim 13 wherein the second and third adhesive materials encapsulate the first and second adhesive layers and the barrier layer. 15. The film structure as claimed in claim 13 wherein the second and third adhesive materials are the same type of material. 16. The film structure as claimed in claim 10 wherein the film structure is formed by passing the second extrudate through a die to form a film. 17. The film structure as claimed in claim 10 wherein the first adhesive material is selected from the group consisting of an acid terpolymer and polyamide. 18. The film structure as claimed in claim 10 wherein the second adhesive material is selected from the group consisting of ethylene methyl acrylate copolymer, ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, polyethylene, polyethylene copolymer and polyethylene copolymer with maleic anhydride. 19. The film structure as claimed in claim 10 wherein said substrate comprises oriented polypropylene and said film structure comprising: a sealant layer laminated to the polypropylene layer; and an outer layer laminated to another outside surface of the second extrudate. 20. A film structure comprising: a plurality of layers; a barrier layer within the plurality of layers wherein the barrier layer is made from ethylene vinyl alcohol; and an adhesive layer disposed adjacent to the barrier layer wherein the adhesive layer binds the barrier layer to at least one of the remaining layers in the plurality of layers and further wherein the adhesive layer is made from an acid terpolymer. 21. The film structure as claimed in claim 20 wherein the acid terpolymer comprises ethylene/methyl acrylate/acrylic acid terpolymer. 22. A method of manufacturing a film structure, the method comprising the steps of: providing a first extruder for extruding a thermally sensitive barrier material, wherein said barrier material is made with ethylene vinyl alcohol; extruding said barrier material; providing a second extruder for extruding a first adhesive material; extruding the first adhesive material; encapsulating the barrier material by the first adhesive material in a first encapsulator to form a first extrudate at a first temperature; providing a second adhesive material; extruding the second adhesive material via a third extruder; adhering the first extrudate to the second adhesive at a second temperature to form a combined meltstream wherein the second temperature is higher than the first temperature; feeding the combined meltstream through a die to form a flat sheet wherein the flat sheet includes a barrier layer encapsulated by first adhesive layers on opposite sides of the barrier layer and further wherein at least one of the first adhesive layers are bonded to a second adhesive layer on an outside surface of the first adhesive layers; and laminating said sheet to at least one substrate formed separately from said sheet; 23. The method as claimed in claim 22 wherein the first temperature is between about 400° F and 450° F and further wherein the second temperature is between about 550° F and 620° F. 24. The method as claimed in claim 22 comprising the steps of: laminating a plurality of layers to the film. 25. The method as claimed in claim 22 wherein the substrate comprises an oriented polypropylene layer. 26. The method as claimed in claim 22 wherein the barrier material is selected from the group consisting of ethylene vinyl alcohol copolymer; ethylene vinyl alcohol copolymer blended with polyamide; ethylene vinyl alcohol blended with polyethylene; polyamide; polyvinylidene chloride copolymers and acrylonitrile. 27. The method as claimed in claim 22 comprising the steps of: combining a third adhesive material to form a third adhesive layer to a second outside surface of the first adhesive layers; laminating an outer layer to an outer surface of the third adhesive layer; and laminating a sealant layer to an outside surface of the polypropylene layer. 28. The method as claimed in claim 22 wherein the first adhesive material is selected from the group consisting of polyamides, polyethylene having maleic anhydride functional groups, ethylene methyl acrylate copolymer, ethylene vinyl acetate copolymer, polystyrene block copolymer and ethylene acrylic acid copolymer. 29 . A film structure made by the method of claims 22 to 28. Coextruted firm having a heat a sensitive barrier layer (110) comprising materials such as EV011, nylon etc, which has been encapsulated by a first adhesive material (112), and additional adhesive layers of a higher melting polymer (113) deposited on the first adhesive layer. The first adhesive layers help to protect the heat sensitive barrier material from the heat of extrusion / lamination.

Documents:

251-kolnp-2003-granted-abstract.pdf

251-kolnp-2003-granted-claims.pdf

251-kolnp-2003-granted-correspondence.pdf

251-kolnp-2003-granted-description (complete).pdf

251-kolnp-2003-granted-form 1.pdf

251-kolnp-2003-granted-form 18.pdf

251-kolnp-2003-granted-form 2.pdf

251-kolnp-2003-granted-form 3.pdf

251-kolnp-2003-granted-form 5.pdf

251-kolnp-2003-granted-letter patent.pdf

251-kolnp-2003-granted-pa.pdf

251-kolnp-2003-granted-reply to examination report.pdf

251-kolnp-2003-granted-specification.pdf

251-kolnp-2003-granted-translated copy of priority document.pdf