NZ236437A - Multilayer packaging film with oxygen barrier core layer - Google Patents

Description

No: Date: . 236437 Priority Date(s): .

Complete Spacification Fi:-:d: Class: tUnu/sp,-.. 6Kifiy/oi Publication Date: .. 2fi.IMY.TO P rng!^[o: NEW ZEALAND PATENTS ACT, 1953 COMPLETE SPECIFICATION PACKAGING MATERIAL FOR SHREDDED CHEESE /We w R GRACE & CO.-CONN, a corporation organized and existing under the laws of the state of Connecticut, USA of 1114 Avenue of the Americas, New York, NY 10036, United States hereby declare the invention for which /f/we pray that a patent may be granted to iji^us, and the method by which it is to be performed, to be particularly described in and by the following statement (foil owed by page la) 2364 BACKGROUND OF THE INVENTION This invention relates generally to the art of packaging films and more particularly to films and laminates useful in the packaging of food products such as cheese.

It is common practice in packaging many goods, including food items, to use what is generally known as form-fill-seal equipment. In the vertical form-fill-seal (VFFS) arrangement, flexible packaging material is fed from a rollstock to a tube former where a tube is fashioned from the sheet material into a vertically dependent, upwardly open tube having overlapping longitudinal edges. These overlapping edges are subsequently sealed together longitudinally by means well known in the art and the end of the tube is sealed together by a pair of transverse heat seals which are vertically spaced apart. At this point the tube is filled with a measured quantity of the product to be packaged, such as shredded cheese. A second heat sealing operation, typically performed after the filled tube has been downwardly advanced, completes enclosure of the product. Simultaneously with or shortly after the transverse heat sealing step the tube is completely transversely severed by known cutting means in a space between the vertically spaced apart pair of transverse heat seals. Thereafter the tube is downwardly advanced and the cycle is successively repeated so as to form a multiplicity of individually packaged products.

Alternatively, a single transverse heat seal formed from a pair of horizontally spaced apart sealing jaws may be used to form in effect 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 1*V ;• 236437 ;two vertically adjacent heat seals which are simultaneously or subsequently severed at a line vertically intermediate the heat seals. ;Horizontal form-fill-seal (HFFS) equipment is also well known in the art for packaging many goods, including food items. ;Flexible packaging material useful for this as well as other applications typically must meet stringent requirements imposed by the particular food or other article to be packaged. ;In some cases, for example, it is desirable to have a packaging material with a broad sealing "window", including a low seal initiation temperature. ;The flexible material must also have sufficient abuse resistance to physical and mechanical abuse imposed by the entire form-fill-seal or other packaging system, and the subsequent abuse which the package may undergo during the distribution cycle. ;Yet another requirement of packaging material, especially in form-fill-seal systems, is good hot seal strength ("hot tack") and cold (final) seal strength with respect to the transverse heat seals, which are typically subjected to loading forces from the introduced product such as food product, soon after the heat seal is formed. Cold seal strengths of at least about ten pounds per inch are preferred. ;When the contained food product is e.g. shredded cheese, contamination can occur in the areas of the packaging material that will form the seals of the final package. Effective encapsulation of this contamination should occur to provide seals with sufficient strength to maintain package integrity during the distribution cycle. ;Still another requirement for such material, when packaging oxygen or moisture sensitive products, is good i.e. low oxygen and moisture vapor transmission rates. ;In VFFS and HFFS applications, it is preferable to have a packaging material with a coefficient of friction (cof) of less than about ;4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 ;2 ;• 2364 ;.3. At higher cof values, it becomes increasingly more difficult to run packaging material on these systems. ;Of interest is U.S. Patent No. 3,912,843 (Brazier) disclosing a flexible packaging film with layers of nylon, biaxially oriented polypropylene, heat sealable polyolefin, and saran. ;Of interest is U.S. Patent No. 4,284,674 issued to Sheptak and disclosing a multilayer film having a core layer of ethylene vinyl alcohol copolymer adhered on each side to nylon, each nylon layer in turn being adhered to a chemically modified polyolefin, and a further layer of primer material suitable to adhere the modified polyolefin to an outer layer of polypropylene or other materials suitable for conveying toughness, flex-crack resistance and moisture barrier properties to the multiply film. ;Also of interest is U.S. Patent No. 4,355,721 issued to Knott et al and disclosing a coextruded multilayer sheet having a first layer of nylon, an EVOH barrier layer, another layer of nylon, an adhesive layer, and another outside layer of, for example, high density polyethylene. ;Of interest is U.S. Patent No. 4,398,635 issued to Hirt and disclosing a medication package in which a coextruded multiple layer sheet may have a structure including a layer of ethylene vinyl alcohol copolymer sandwiched between adjacent layers of nylon, and in which one of the nylon layers may be further adhered to a tie resin. The nylon layers may form either an outside surface or, in one example, internal layers with additional layers of polymeric materials added to each side of the sandwich structure. ;Of interest is U.S. Patent No. 4,405,667 issued to Christensen et al, disclosing a packaging material for retort applications including a heat seal layer of linear low density polyethylene, a seventh and ninth layer of nylon, and an eighth layer of EVOH. ;Of interest is U.S. Patent No. 4,407,873 issued to Christensen et al, disclosing a packaging material for retort applications including a heat seal layer of linear low density polyethylene, a second layer of ;4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 ;3 ;236437 ;linear low density polyethylene with optionally 0% to 80% medium density polyethylene blended into the second layer, a third layer of anhydride modified medium density polyethylene, a fourth layer of nylon, a fifth layer of ethylene vinyl alcohol copolymer, and a sixth layer of nylon. ;Of interest is U.S. Patent No. 4,421,823 (Theisen et al) disclosing a laminate having an outer layer of polypropylene or polyester, an oxygen barrier layer, and a polyethylene layer. ;Of interest is U.S. Patent No. 4,457,960 issued to Newsome, disclosing a multilayer film having a core layer of a barrier material such as EVOH and EVOH blends. This film may be shrinkable and may be melt extruded, and may contain outside layers having a blend of linear low density polyethylene and ethylene vinyl acetate copolymer. ;Of interest is U.S. Patent No. 4,495,249 issued to Ohya et al, disclosing a five-layer film having a core layer of a saponified copolymer of ethylene and vinyl acetate, outer layers of a mixture of linear low density polyethylene and ethylene vinyl acetate copolymer, and two adhesive layers disposed between the core layer and outer layers. ;Of interest is U.S. Patent No. 4,501,798 (Koschak et al) disclosing a film with surface layers of nylon and ethylene copolymer and an interior layer of EVOH. ;Of interest is U.S. Patent No. 4,640,852 (Ossian) disclosing a multiple layer film having a layer of nylon on each side of an EVOH layer, and additional layers of modified polyethylene and linear low density polyethylene or propylene ethylene copolymer. ;Of interest is U.S. Patent No. 4,683,170 (Tse et al) disclosing a film having a nylon surface layer, a heat sealable surface layer, and interior layers of EVOH, adhesive, and polyethylene or polypropylene. ;Of interest is U.S. Patent No. 4,735,855 (Wofford et al) disclosing a laminate with a core layer of an oxygen barrier material, a poly amide on each surface of the core layer, a sealant layer, a second surface layer, and intermediate adhesive layers. ;4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 ;4 ;236437 ;Of interest is U.S. Patent No. 4,746,562 (Fant) disclosing a film with a core layer of EVOH, intermediate polyamide layers, outer linear low density polyethylene layers, and adhesive layers. ;Of interest is German Patent No. 3035474 Al (Schroeder) disclosing a multilayer construction having an internal layer of EVOH, outer layers of nylon and Surlyn™, and an intermediate layer of Plexar™. ;It is an object of the present invention to provide a multilayer film or laminate suitable for the packaging of food products, especially food products such as shredded cheese which can contaminate the seal areas of a VFFS or HFFS pouch. ;It is a further object of the present invention to provide a multilayer film or laminate with a broad sealing "window", including low seal initiation temperature. ;It is still another object of the present invention to provide a multilayer film or laminate which provides extended shelf life to food products. ;It is yet another object of this invention to provide a film or laminate with good abuse resistance. ;Another object of the present invention is to provide a packaging material with good hot and cold seal strengths when used in a VFFS or HFFS system, even when the seals are contaminated by food product. ;An additional object of the present invention is to provide a packaging material with a coefficient of friction of less than about .3. ;SUMMARY OF THE INVENTION ;The instant invention is directed to a polymeric film comprising a core layer comprising an oxygen barrier material; an internal polyamide layer disposed on each surface respectively of the core layer; a sealant ;4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 ;5 ;layer comprising very low density polyethylene; an outer heat resistant layer; arid an intermediate layer disposed between the internal polyamide layer and the sealant layer and an intermediate layer disposed between the internal polyamide layer and outer heat-resistant layer, each intermediate layer comprising a chemically modified polyolefin. ;In another aspect of the present invention, a method for producing a film comprises coextruding a core layer comprising an oxygen barrier material; an internal polyamide layer disposed on each surface respectively of the core layer; a sealant layer comprising very low density polyethylene; ail outer heat resistant layer ; and an intermediate layer disposed between the internal polyamide layer and the sealant layer, and an intermediate layer disposed between the internal polyamide layer and the outer heat-resistant layer, each intermediate layer comprising a chemically modified polyolefin; said layers extruded through several extruders; joining said extruded layers at a die to form a total coextrusion; drawing the coextrusion from the die; quenching the coextrusion; and winding the coextrusion into rolls. ;In yet another aspect of the invention, a laminate comprises a polymeric film having a core layer comprising an oxygen barrier material, an internal polyamide layer disposed on each surface respectively of the core layer, a sealant layer comprising very low density polyethylene, an outer layer comprising a polymeric material selected from the group consisting of polyamide, polypropylene, polyester, polycarbonate, high density polyethylene, linear low density polyethylene, and copolymers and an intermediate layer disposed between the internal polyamide layer and the sealant layer and an intermediate layer disposed between the internal polyamide layer and the outer layer, each intermediate layer comprising a chemically modified polyolefin; and a substrate adhered to the outer polymeric layer of the polymeric film, and comprising polyester or polypropylene. ;DEFINITIONS ;"Oxygen barrier" is used herein to refer to polymeric materials having oxygen transmission rates of preferably less than about 100cc/m,2 in 24 hours at 73°F (STP), and more preferably less than about 10cc/m2, ;4/891212.5A/TXTGH/01:45:31 PM/June 1, 1990 £ ^ ; ;6 ;V ;* \ ^ MUG?993 ' 1 • 23 6 4 24 hours, 73°F (STP)(ASTM D 3985). Such materials include e.g. ethylene vinyl alcohol copolymer, and vinylidene chloride copolymers, although polyamides are to some extent useful in providing oxygen barrier properties.

"Polyamide" is used herein to refer to high molecular weight polymers having amide linkages along the molecular chain, and refers more specifically to synthetic polyamide such as various nylons.

"Ethylene vinyl alcohol copolymer" is used herein to refer to a vinyl alcohol copolymer having an ethylene comonomer, and prepared by e.g. hydrolysis of vinyl acetate copolymers, or by chemical reactions with polyvinyl alcohol.

"Polyolefin" is used herein broadly to include polyethylene, ethylene copolymers having a small amount of a comonomer such as vinyl acetate, ethylene-alpha olefin copolymers (LLDPE), polypropylene, polybutene, and other resins falling in the "polyolefin" family classification.

"Very low density polyethylene" is used herein to mean a linear ethylene alpha olefin copolymer having densities of generally between 0.880 and 0.915 grams/cubic centimeter, and produced by a catalytic process.

BRIEF DESCRIPTION OF THE DRAWINGS Further details are given below with reference to the drawings, wherein: Fig. 1 is a schematic cross-section of a preferred embodiment of a polymeric film of the invention; and Fig.2 is a schematic cross-section of a preferred embodiment of a laminate of the invention. 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 7 • 23 6 4 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Fig. 1 a schematic cross-section of a preferred embodiment of the film of the invention is shown. The film structure is directed to a multi-layer composite having the generalized structure of (outside) A/B/C/D/C/B/E (inside) where A is an outer heat resistant layer, B is an intermediate adhesive layer, C is an internal polyamide layer, D is an oxygen barrier layer, and E is a sealant layer.

Outer layer 10 serves as a heat resistant and an abuse resistant layer, and preferably is a polyamide such as nylon 6, nylon 6,66, nylon 6,12 or nylon 6,10. A commercially available resin is Capron 8207 F from Allied or Ultramid C35 from BASF. When used as the outermost layer of a packaging material, layer 10 should have sufficient heat resistance to withstand the longitudinal and transverse sealing operations that are part of a typical form/fill/seal process. Polyamides such as nylon 6 and nylon 6,66 offer good flex crack resistance as well as resistance to the formation of pinholes. Other materials suitable for layer 10 include polyester, polypropylene, polycarbonate, and high density polyethylene.

Oxygen barrier layer 16 is preferably an ethylene vinyl alcohol copolymer such as Soarnol ET available from Nippon Goshei. This material exhibits excellent oxygen barrier properties at low humidities with lesser barrier qualities at higher humidities.

On either side of the barrier layer 16 are internal polyamide layers 14 preferably comprising nylon 6.

Sealant layer 20 is preferably a very low density polyethylene (VLDPE) such as Attane 4004, available from Dow. This material is sometimes referred to as ultra low density polyethylene. Particularly preferred VLDPE has a density in the range of .900 to .910 grams/cubic centimeter. Another suitable material is ionomer, a metal salt-neutralized copolymer of ethylene and acrylic or methacrylic acid. Other suitable sealant materials include polyolefins, ethylene-alpha olefin copolymers, and blends thereof. 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 8 236437 Intermediate tie layers 12 and 18 respectively assure adhesion between internal layers 14 and outer layer 10 and sealant layer 20 respectively. These intermediate tie layers may be identical or different from each other, and may include a wide range of chemically modified and anhydride/grafted polyolefins including those based on ethylene vinyl acetate copolymer, polypropylene, low density polyethylene, linear low density polyethylene, and very low density polyethylene. Commercial examples of such materials are those marketed under the name Plexar available from Quantum, the CXA series from DuPont, and the like. A preferred commercial resin is Bynel CXA 3095, a chemically modified ethylene vinyl acetate copolymer available from DuPont.

The film of the present invention provides good optical properties including clarity and high gloss, good color retention (in meat products), extended shelf life, and good hot and cold seal strength even in the case of contaminated seals.

Films in accordance with the present invention may be made by extruding the various resins through five, six or seven extruders. The extrudate is passed through a die where the layers are joined and form a total coextrusion. The multilayer composite exits the die lips and is hot blown and then cooled.

Two of the resin streams can be split to provide the internal polyamide layers and the intermediate adhesive layers. In the event that layers 12 and 18 comprise different resins, an additional extruder is used.

When intended for use in a VFFS or HFFS application, the film is hot blown by techniques well known in the art, to a blow up ratio of between 2:1 and 3:1. Optionally, the film could be irradiated which would cross-link ethylene vinyl acetate copolymer adhesive layers 12 and 18 in the event that such resins were used in the adhesive layers. The film can also be chemically cross-linked by means of commercially available chemical cross-linking agents.

In order to reorient the film, it could be longitudinally oriented, calendared, and/or tenterframed. 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 9 0 23 6 4 Referring to Fig.2, in an alternative embodiment, a substrate 30 can be laminated by conventional adhesives 32 to the film of the present invention. The substrate is adhered at the outer surface layer 10 of the film. When practicing this embodiment, layer 10 is not an outermost surface of the final laminate. The choice of materials suitable for layer 10 is in this case broadened to include ethylene alpha olefins such as linear low density polyethylene (LLDPE)(e.g. Dowlex 2044A), or other materials which do not necessarily possess the abuse resistance or heat resistance of polyamide for VFFS and HFFS applications. LLDPE adds pinhole resistance and favorable mechanical properties to the final laminate.

Commercially available substrates are typically polyester or polypropylene films with or without an interior coating of vinylidene chloride copolymer (saran). The coating adds to the oxygen barrier properties of the overall laminate, especially at high relative humidity conditions. The interior surface of the polyester or polypropylene substrate is optionally trap printed.

The films or laminates of the present invention are particularly suited for packaging of cheese products such as shredded cheese.

The invention may be further understood by reference to the following examples which appear in Table 2. These examples were produced by extruding the various resins listed through separate extruders, except that the internal polyamide layers were extruded as a split stream from a single extruder, and the two tie layers were also extruded as a split stream from a single extruder.

In each example, the extrudates were joined in the arrangement described where they entered a coextrusion die. The resulting composite exited the die lips and was hot blown at a ratio of between 2:1 and 3:1. The hot blown film was then cooled, then collapsed and wound into mill logs, and slit to the desired width using Dusenbury slitters.

The resulting films of Examples 1-5 and 7-8 had an overall thickness of about 2.0 mils. The films of Examples 6 and 9-10 were each produced in final thicknesses of about 2.5 mils and 3.0 mils. 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 236437 Films of the present invention are preferably 1.0 to 5.0 mils thick.

Table 1 identifies the resins that were used in the examples of Table 2.

Table 1 EV0Ht SOARNOL ET (NIPPON GOHSEI) LLDPEt LLDPE2 DOWLEX 3010 DOWLEX 2044A (DOW) (DOW) VLDPET ATTANE 4004 (DOW) I \ I2 SURLYN 1702 (MODIFIED) SURLYN 1702 (DUPONT) (DUPONT) NYLON, NYLON? NYLON;l CAPRON 8207 F ULTRAMID KR-4407 f ULTRAMID C 35 (ALLIED) (BASF) (BASF) TIE, TIEZ TIE3 PLEXAR 3 ADMER NF 500A BYNEL CXA 3095 (QUANTUM/USI) (MITSUI) (DUPONT) A 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 11 9 23 6 4 "EVOH" is ethylene vinyl alcohol copolymer. "LLDPE" is linear low density polyethylene. "VLDPE" is very low density polyethylene, and as used in Examples 1 through 9 represents the sealant or food contact layer of the film. "I" is ionomer. The modification in "I1" is the addition of 5,000 parts per million (ppm) of Superfine Superfloss™, an antiblock agent commercially available from Johns Manville. The commercial polyamides listed are all Nylon 6.

Table 2 Examples Polymeric Film 1 LLDPE,/TIE,/NYLON , /EVOH,/NYLON ,/TIE,/VLDPE, 30 5 12.5 10 12.5 5 25 2 LLDPE, /TIE, /NYLON, /EVOH, /NYLON ,/TIE, /VLDPE, 35 5 10 10 10 5 25 3 LLDPE,/TIE,/NYLON,/EVOH,/NYLON,/TIE,/VLDPE, 35 5 7.5 10 7.5 5 30 4 LLDPE ,/TIE2/NYLON,/EVOH,/NYLON,/TIE;,/1, 35 5 7.5 10 7.5 5 30 LLDPE,/TIE2/NYLON,/EVOH,/NYLON ,/TIE;?/Ip 35 5 7.5 10 7.5 5 30 6 NYL0N2/TIE, /NYLON, /EVOH, /NYLON, /TIE, /VLDPE, 10 15 7.5 10 7.5 15 35 7 LLDPE2/TIE, /NYLON, /EVOH,/NYLON,/TIE,/VLDPE, 35 5 10 10 10 5 25 8 LLDPE;,/TIE, /NYLON, /EVOH, /NYLON ,/TIE, /VLDPE, 35 5 10 10 10 5 25 9 NYLON2/TIE3/NYLON, /EVOH, /NYLON, /TIE.-,/VLDPE, 10 15 7.5 10 7.5 15 35 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 12 23 6 4 NYLON.-, /TIE3/NYLON, /EVOH T /NYLON t/TIE,,/VLDPE, 15 7.5 10 7.5 15 35 In each of the examples, the values listed under each layer are the percent of the film structure formed by the respective layers.

In each of Examples 1 through 3 and 6 through 10, the sealant layer (VLDPE) contained a small percentage (3 to 4%) of Ampacet 10853. This is a polyethylene masterbatch with 6 parts per thousand of an antiblocking agent (diatomaceous earth).

In Example 1, Attane 4001 (Dow) was used at first in the sealant layer, but because of bubble instability, the Attane 4004 was used instead.

In each of Examples 4 and 5, the ionomer sealant layer included a small percentage of Superfine Superfloss™, an antiblock agent from Johns Manville.

The outer nylon layers of Examples 6, 9 and 10 also contained small amounts of slip and antiblock agents.

Each of the coextruded films of Examples 1 to 5, 7 and 8 was laminated by conventional means to a substrate of a 75 gauge biaxially oriented polypropylene, B523™, available from Hercules.

Each of the coextruded films of Examples 1 to 5, 7 and 8 was also laminated to a 48 gauge polyester substrate, Mylar™, available from DuPont.

Each of the coextruded films of Examples 1 to 5 , 7 and 8 was also laminated to a 50 gauge coated polyester substrate, Scotchpar 2708™ available from Minnesota Mining and Manufacturing.

In the case of each laminate thus formed, the substrate was adhered to the coextruded film at the interface between the substrate and the outer layer of the coextruded film. 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 13 0 23 6 4 Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be utilized without departing from the principles and scope of the invention, as those skilled in the art will readily understand. Accordingly, such modifications and variations may be practiced within the scope of the following claims. For example, although the preferred process for producing the polymeric film of the present invention is a coetrusion process, other processes such as extrusion coating and conventional lamination can also be used to combine the layers of the polymeric film. 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 14

Claims (14)

WHA 1/fm CLAIM IS

1. A polymeric film comprising: 3643/ a) a core layer comprising an oxygen barrier material; b) an internal polyamide layer disposed on each surface respectively of the core layer; c) a sealant layer comprising very low density polyethylene; d) an outer heat resistant layer; and e) an intermediate layer disposed between the internal polyamide layer and the sealant layer and an intermediate layer disposed between the internal polyamide layer and outer heat-resistant layer, each intermediate layer comprising a chemically modified polyolefin.

2. |he polymeric film according to claim 1 wherein the oxygen barrier material comprises ethylene vinyl alcohol copolymer.

3. The polymeric film according to claim 1 wherein the internal

4- The polymeric film according to claim 1 wherein the outer heat resistant layer is a polymeric material taken from the group consisting of polyamide, polyester, polypropylene, polycarbonate, high density polyethylene, and copolymers and mixtures thereof.

5. The polymeric film according to claim 1 wherein the sealant la^er further comprises a small amount of an antiblock agent.

The polymeric film according to claim 1 wherein the chemically modified polyolefin comprises a polyolefin selected from the group consisting of ethylene vinyl acetate copolymer, polypropylene, low density polyethylene, linear low density polyethylene and very low density polyamide comprises nylon 6. polyethylene. >1 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 15 •, 2 8 MAR 1994." 2-5 64-^7

7. A method for producing a laminate, comprising: a) coextruding a core layer comprising an oxygen barrier material; an internal polyamide layer disposed on each surface respectively of the core layer; a sealant layer comprising very low density polyethylene; an outei- heat resistant layer ; and ail intermediate layer disposed between the internal polyamide layer and the sealant layer and an intennediate layer disposed between the internal polyamide layer and the outer heat-resistant layer, each intermediate layer comprisina a chemically modified polyolefin; said layers extruded through at least one separate extruder for the extrusion of each layer, b) joining said layers at a die to form a total coextrusion; c) d) e)

8. The method according to claim 7 wherein the adhesive layers and sealant layers are cross-linked.

9. The method according to claim 7 wherein the coextrusion is longitudinally oriented.

10. A laminate comprising: a) a polymeric film having i) a core layer comprising an oxygen barrier material; drawing the coextrusion from the die; f" quenching the coextrusion; and winding the coextrusion into rolls. N.Z. L . ii) an internal polyamide layer disposed on each surface respectively of the core layer; 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 16 iii) a sealant layer comprising very low density polyethylene; iv) an outer layer comprising a polymeric material selected from the group consisting of polyamide, polypropylene, polyester, polycarbonate, high density polyethylene, linear low density polyethylene, and copolymers and mixtures thereof; v) an intermediate layer disposed between the internal polyamide layer and the sealant layer and an intermediate layer disposed between the internal polyamide layer and the outer layer, each intermediate layer comprising a chemically modified polyolefin^ and b) a substrate adhered to the outer polymeric layer of the polymeric film, and comprising polyester or polypropylene.

11. A laminate of claim 10 further comprising a coating of vinylidene chloride copolymer on an interior surface of the substrate.

12. A polymeric film substantially as herein described with reference to the figure 1 of the accompanying drawings.

13. A method for producing a laminate substantially as herein described with reference to the accompanying drawings.

14. A laminate substantially as herein described with reference to figure 2- of the accompanying drawings. — By ytie) their auftorHwd Aqw* AJ. PARK & SON. 4/891212.5A/TXTGM/01:45:31 PM/June 1, 1990 17