NZ239561A - Multi-layer cook-in laminate with food contact layer comprising lldpe and ethylene/alpha-olefin and optionally an anti-block agent - Google Patents

Description

2 6 OCT 1993 I 'o 1 o MEW ZEALAND PATENTS ACT, 1953 f*>Z. PARENT OF^FISS No.

Da t6 '■ 27 AUG 1991 receiver COMPLETE SPECIFICATION BARRIER COEXTRUDED FILM FOR COOK-IN APPLICATIONS fc/We, W R GRACE & CO.-CONN, a corporation of the State of Connecticut, of 1114 Avenue of the Americas, New York, New York 10036, United States of America, hereby declare the invention for which>L/Ke pray that a patent may be granted to ;£/We, and the method by which it is to be performed, to be particularly described in and by the following statement:- BACKGROUND OF THE INVENTION This invention relates generally to gas impermeable, thermoplastic packaging film which can be heat sealed to itself or to another material to form a flexible or semi-flexible package. The invention relates more particularly to z'ne use of such film in packaging food products in which the packaged product is submerged in heated water or autoclaved or retorted for a substantially period of time for pasteurizing or cooking the packaged product, the packaging material being essentially non-degradable under such conditions.

There is a need in the food packaging industry for a packaging film from which packages can be made which are of improved structural soundness, and provide excellent toughness and package integrity in cook-in applications. The cooking conditions are often severe enough to cause delamination or degradation of the packaging material in some cases. For the sake of package appearance, it is desirable to have a precooked food product which is attractively packaged inside a preferably transparent film within which it is precooked.

The term "pasteurizable" as used herein is intended to refer to packaging material structurally capable of withstanding exposure to pasteurizing conditions while containing a food product. Many food products require pasteurization after they have been hermetically packaged to destroy harmful microbes which grow in the absence of air. Specific pasteur- la ization requirements tend to vary by country; however, limiting conditions probably are submersion of the hermetically sealed product in water at 95°C for one hour. Thus, for a bag to be characterized as pasteurizable, structural integrity of the bag must be maintained during pasteurization, i.e. the bag must have superior high temperature seal strength and must be delamination resistant under such time-temperature conditions.

Optionally, the packaging material is heat shrink-able under pasteurizing conditions so as to provide an attractively packaged pasteurized food product.

The term "cook-in" as used herein is intended to refer to packaging material structurally capable of withstanding exposure to cook-in time-temperature conditions while containing a food product. Cook-in packaged foods are essentially prepackaged, precooked foods that go directly to the consumer in that configuration which may be consumed with or without warming. Cook-in time-temperature conditions typically refer to a long slow cook, for example submerging in water at 70°-80°C for four to six hours. Such cook-in time-tempera-ture requirements are representative of institutional cooking requirements. Submerging at 80°C for twelve hours probably represents the limiting case. Under such conditions, a packaging material properly characterized as cook-in will maintain seal integrity and will be delamination resistant. Optionally, the packaging film is heat shrinkable under these conditions so as to form a tightly fitting package and preferably should have some tendency for product adhesion to prevent cook out or collection of juices between the surface of the food product and the interior surface of the packaging material.

A number of characteristics are required for cook-in packaging film. First, packages made from such film must have seal integrity under such conditions i.e. the heat sealed seams should resist being pulled apart. As a corol- 7/900803.3/SPECFLDR 2 lary, the film should be heat sealable either to itself or to another material. In the case of cook-in packages having thermoformed cavities for placement of a product, a non-form-ing cover web is typically vacuum sealed to the formed web to create the cook-in package.

Secondly, such materials must be delamination resistant, i.e. the multilayers making up the film must not separate or blister.

Additionally, the food contact layer of such film must qualify under the appropriate food laws and regulations for safe food contact.

A fourth consideration is the oxygen barrier or vapor barrier properties of the material, which are preferably high to maintain the freshness of the food contained therein.

Additional desirable characteristics in some package applications are heat shrinkability during the cook-in process to provide a packaging material which fits snugly around the product contained therein, as well as optical clarity where eye appeal of the packaged product is desired.

Various cook-in packaging materials are currently available in the market place. U. S. Patent No. 4,469,742 issued to Oberle et al describes a pasteurizable and/or cook-in shrink film which employs a hydrolyzed ethylene vinyl acetate copolymer (ethylene vinyl alcohol copolymer or EVOH) in an irradiated, multilayer structure suitable for cook-in applications.

Another current film structure, such as shown in U. S. Patent No. 4,683,170 (Tse et al), has a five layer construction in which a core layer of ethylene vinyl alcohol copolymer is adhered to an inner ionomeric sealant layer, and to an outer nylon abuse layer, by means of respective tie 7/900803.3/SPECFLDR 3 • 23 9 5 6 1 layers, one on either side of the core layer. This latter structure requires the use of relatively thick tie layers.

In some cases these tie materials, such as the Plexar series of resins available from Quantam and the CXA series of polymeric adhesive resins available from du Pont, are typically very specialized and relatively expensive materials.

Also of interest is U.S. Pat. No. 4,735,855 to Wofford, et al which discloses a thermoformable polymeric laminate having a core layer of an oxygen barrier material, a polyamide layer disposed on either side of the core layer, the polyamide having controlled crvstallinity, a sealant layer, an outer layer of a moisture barrier material, preferably polypropylene, and an intermediate layer disposed between the polyamide layer and each of the sealant layer and outer layer respectively, the intermediate layer being an anhydride grafted polyolefin.

Also of some interest is U.S. Pat. No. 4,457,960 to Newsome which discloses a film structure for use in shrink bags including a sealing layer which may be a blend of linear low density polyethylene and ethylene/vinyl-acetate copolymers.

Of similar interest is U.S. Pat. No. 4,801,486 to Quacquarella et al which discloses a film structure for use in shrink bags including a sealing layer which may be a blend of linear low density polyethylene and very low density polyethylene .

SUMMARY OF THE INVENTION It is an object of the present invention to go soire way towards meeting the above-mentioned desiderata, or at least to provide the public with a useful choice.

The present invention is directed to a polymeric laminate comprising a core layer comprising an oxygen barrier material; a polyamide layer disposed on each surface respectively of the core layer, the polyamide layer having controlled crystallinity; a sealant layer; an outer abuse layer; and an intermediate layer disposed between the n polyamide layer and each of the sealant layer and outer layer respectively, and comprising an anhydride grafted polvolefin.

In another aspect of the present invention, a method for producing a laminate comprises coextruding a core layer comprising an oxygen barrier material; a polyamide layer disposed on each surface respectively of the core layer, the polyamide having controlled crvstallinity; a sealant layer; an outer abuse layer; and an intermediate layer disposed between the polyamide layer and each of the sealant layer and outer layer respectively, ana comprising an anhydride grafted 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 a further aspect the present invention consists in a multiple-layer, cook-in laminate having a first food contacting and sealing layer conprising: from about 5% to about 95% by weight of linear lav density polyethylene; from about 5% to about 95% by weight of ethylene/alpha-olefin copolymers having a density of less than 0.915 g/cc; and from about 0% to about 2% by weight of an anti-block agent.

In a further aspect the present invention consists in a method of making a cook-in film conprising: coextruding an inner sealing layer conprising from about 5% to about 95% by weight of linear lav density polyethylene and from about 5% to about 95% by weight of other ethylene/alpha-olefin copolymers having a density of less than 0.915 g/cc, a barrier layer and an abuse layer conprising a polyamide; and quenching the coextruded film. (followed by page 5a) DEFINITIONS "Controlled crystallinity" refers to at least some control in the nature and extent of crystallization in a polyamide, resulting in a package with adequate or improved package tightness. Preferably, controlled crystallinity of polyamides is achieved by including a small amount of a nucleating agent such as talc. These agents are believed to set up nucleating sites in the resin around which more consistently sized crystallites grow. This in turn provides improved package tightness.

"Corona discharge treatment" or "corona treating" are used herein to refer to subjecting the surfaces of thermoplastic materials, such as polyolefins, to corona discharge, i.e. the ionization of a gas such as air in close proximity to a film surface, the ionization initiated by a high voltage passed through a nearby electrode, and causing oxidation and other changes to the film surface. 5a "Oxygen barrier" is used herein to refer to polymeric materials having oxygen transmission rates of less than about 10cc/m,2 in 24 hours at 73°F (STP), and preferably less than about lcc/m2, 2 4 hours, 73 °F (STP). Such materials include e.g. ethylene vinyl alcohol copolymer, and vinylidene chloride copolymers.

"Polyamide" is used molecular weight polymers having molecular chain, and refers more polyamide such as various nylons. herein to refer to high amide linkages along the specifically to synthetic "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, polypropylene, polybutene, and other resins falling in the "polyolefin" family classification.

"LDPE" designates branched chain polyethylene made by the high pressure process and will have a density below 0.940 g/cc and, most often a density of 0.915 to 0.925 as the 0,926 to 0.939 range is often referred to as the medium density range.

"LLDPE" refers to linear low density polyethylene which generally is understood to include that group of ethylene/alpha-olefin copolymers having limited side chain branching and which fall into a density range of 0.910 to 0.940 g/cc. Sometimes linear polyethylene in the density range from 0.926 to 0.940 is referred to as linear medium density polyethylene (LMDPE). Typical brand names are Dowlex from Dow Chemical Company, Ultzex and Neozex from Mitsui 7/900803.3/SPECFLDR 6 •"% A & rfl sJ s? v* fl Petro Chemical Company, and Sclair from duPont. The alpha-olefin copolymers are typically butene-1, pentene-1, hexene-1, octene-1, etc.

"Very low density polyethylene" (VLDPE) and "ultra-low density polyethylene" (ULDPE) refer to ethylene/alpha-olefin copolymers which have a density of less than about 0.915 and, more specifically, usually 0.912 or below and may be below 0.89. Typical VLDPE resins are those designated DFDA by Union Carbide and are believed to principally or usually have butene, or isobutene as a comonomer. The very low density polyethylenes as compared to LLDPE, usually have significantly higher copolymer content and distinctly different properties making them a distinct class of polymers. Typically, resins designated "ULDPE" resins come from Dow and are believed to have octene as the comonomer. There is a slight difference in properties which is thought to be attributable to the comonomer. As used herein the term "linear ethylene/alpha-olefin copolymer having a density of less than 0.915 g/cc" encompasses both VLDPE and ULDPE. (See "Plastics Technology Magazine" for September, 1984 at Page 113 where an article entitled, "INTRODUCING VERY LOW DENSITY PE" appears.) BRIEF DESCRIPTION OF THE DRAWINGS Further details are given below with reference to the sole figure drawing, wherein Fig. 1 is a schematic cross-scction of a preferred embodiment of a cook-in structure in accordance with the present invention. 7/900803.3/SPECFLDR 7 <L Q \ «> Q • 3 1 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring specifically to the sole drawing, in Fig. 1 a schematic cross-section of a preferred embodiment of the cook-in laminate 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 abuse layer, B is an intermediate adhesive layer, C is a polyamide layer, D is an oxygen barrier layer, and E is a sealant layer.

Outer layer 10 serves as an abuse layer. Preferably, outer layer 10 is a polyamide, more preferably, a nylon 6 such as Ultramid KR-4407F provided by BASF. A minor amount of an antiblock agent, such as 10853 provided by Ampacet, may also be included in layer 10.

Oxygen barrier layer 16 is preferably an ethylene vinyl alcohol copolymer such as EVAL EP-H101A available from Evalca. 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 polyamide layers 14 comprising nylon 6 and more preferably nucleated nylon 6. The nucleating agent in the nylon 6 is believed to set up nucleation sites around which more consistently sized crystallites grow. This in turn provides improved package tightness in the final packaged product. A suitable nucleating agent is, for example, talc.

Sealant layer 20 generally serves as both a food contacting and a sealing layer and is preferably a blend of linear low density polyethylene and some other ethylene copolymer. For example, it has been found that a blend of LLDPE and ULDPE provides for good high temperature sealing in 7/900803.3/SPECFLDR 8 O "■ ^ £ 0 rn o the cook-in regime and also for good lower temperature tack sealing. Thus, when a non-forming web in accordance with the present invention is sealed to a forming web, also of the present invention, both the high pressure seal, formed by heating the two webs between high pressure seal bars and the low pressure seal, which is formed by atmospheric pressure when the filled package is evacuated, are capable of withstanding the rigors of the cook-in regime. Also within the scope of the present invention are blends of LLDPE with EVA or VLDPE. Furthermore, when corona treated, preferably within the range of from about 40 dynes/cm to about 60 dynes/cm and most preferably at about 50 dynes/cm, all of such blends demonstrate a synergistic effect in providing improved protein adhesion.

The sealing layer may include in the range of about 5". to 95% by weight LLDPE and, correspondingly, 5% to 95% of other ethylene copolymers. Preferably an othylcnc/alpha-olefin is blended with the LLDPE, most preferably ULDPE, with such comprising 15% by weight of the sealant layer. Generally, sealability increases with increasing ULDPE. Thus, for embodiments having very high ULDPE content, such as that disclosed below in Example 7, lower seal temperatures are required for the high pressure seal and greater seal tack is demonstrated by the low pressure sea. Correspondingly, if EVA is blended with LLDPE in the sealant layer, sealability will increase with increasing EVA.

As depicted in the figure, the sealant layer is preferably a relatively thick layer, more preferably forming in excess of 30% of the total film structure thickness. This provides some moisture protection for the core layer 16.

It is also preferred that the sealant layer or the abuse layer or both include a minor portion of an antiblock agent for ease of handling. It was found that the same mechanism of the present invention which provides for improved protein adhesion of the sealant layer to the pack- 7/900803.3/SPECFLDR 9 C >. 1 " — r* J xk aged meat product during cooking also keeps the film from coming off of the roll because of adhesion of the sealant layer to the abuse layer. Because inclusion of antiblock in the polyamide abuse layer, such as is described below in Examples 1, 2, and 3, reduces the optical qualities of the present laminate, it is most preferred that such agent is included only in the sealant layer. Thus, one preferred sealing layer composition includes 83% by weight LLDPE, 15% by weight ULDPE and 2% by weight of an anti-block agent.

Tie layers 12 and 18 respectively assure adhesion between polyamide layers 14 and outer layer 10 and sealant layer 20 respectively. These tie layers may be identical or different from each other, and may include a wide range of 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 Norchem, the CXA series from DuPont, and the like.

In one embodiment of the present invention, the multilayer film can be used as a non-forming web in combination with a forming web to produce the final package. In a typical packaging operation, a forming web is formed into a mold to provide a film cavity in which a food product is placed. Many meat products are packaged in this manner. A non-forming web such as the web of this invention can then be placed over the cavity and vacuum sealed by means well known in the art to the periphery of the forming web. The sealant layer 20 will then bond to the sealant material of the forming web. Of course, the film can also be bonded to itself where it is desirable to use the film to make a bag or pouch.

One advantage of the present invention is that it may be corona treated for excellent protein adhesion during cook-in. However, the present sealing layer is also well suited for cook-in applications for which either no protein 7/900803.3/SPECFLDR adhesion or only limited protein adhesion is preferred. For e".ample, in skin-on turkey breast cook-in processes the skin is either left on the breast or removed from and then replaced onto the turkey breast during preliminary treatment. In either case, protein adhesion of the turkey skin to the inner sealant layer during cook-in will cause the skin to strip from the turkey meat during removal of the package by the consumer. Thus, for such application it is preferred that the forming web, which is drawn into the shape of a turkey breast and which contacts the skin, has a sealing layer which does not exhibit protein adhesion qualities. In such cases, cook-out is limited by providing a non-forming web, which does not contact the breast skin, having protein adhesion qualities. Furthermore, by the present invention, a corona treated non-forming web may be sealed to a non-corona treated forming web with the excellent sealing properties discussed above with respect to both high pressure and low pressure seals being achieved.

The present cook-in structure represents several other significant improvements over the prior art. For example, the nylon abuse layer of the present film has a high heat resistance and can withstand the high sealant temperatures associated with the sealing of non-forming webs to forming webs. Such property is also important for an abuse layer which must withstand the time and temperature requirements of the cook-in regime. Moreover, because nylon is not very thermally insulative, such an abuse layer allows the interior of the film, which is held against the cold meat product therein, to experience a higher temperature in the shrink tunnel, thereby providing improved free shrink.

However, because nylon is not a very effective moisture barrier, it has been found useful to thicken tie layer 12 which binds the outer abuse layer to that inner nucleated nylon 6 layer which is adjacent the moisture sensitive EVOH core. Because of the expense involved in providing such a thickened tie layer, it has further been found to be 7/900803.3/SPECFLDR 11 advantageous to provide two relatively thin tie layers between which is interposed a relatively thick intermediate layer of, preferably, an ethylene alpha-olefin copolymer.

Laminates 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 quenched. The film is wound into mill logs, and then taken, for example, to a Dusenbury slitter to be slit to the desired width.

Two of the resin streams can be split to provide the polyamide layers and the adhesive layers. In the event that layers 12 and 18 comprise different resins, an additional extruder is used. The outer layer 10 may actually be extruded through two contiguous extruders, in which case an additional extruder would be required.

In order to optionally orient the laminate, it could be longitudinally oriented, calendared, and/or tenterframed.

The invention may be further understood by reference to the following examples.

EXAMPLE 1 A thermoformable cook-in laminate was prepared in accordance with the present invention by extruding the various resins listed below through six separate extruders.

A first extruder provided a sealant layer comprising a blend of 15% ethylene/vinyl-acetate (PE1375 from Rexene 7/900803.3/SPECFLDR 12 which has 3.6% vinyl-acetate), 83% LLDPE (Dowlex 2044A from Dow), and 2% of an antiblock agent (10853 from Ampacet).

A second extruder provided an LLDPE based adhesive (Bynel 4125 from Dow).

A third extruder provided a split stream of a nucleated nylon 6 (Ultramid KR4418).

A fourth extruder provided the core layer of an oxygen barrier material (EVAL EP-H101A ethylene vinyl alcohol copolymer from EVALCA).

A fifth extruder provided an ethylene vinyl ace-tate-based anhydride-grafted polymeric adhesive (DuPont Bynel CXA 3095).

A sixth extruder provided an abuse layer comprising a blend of 98% of polycaprolactam, nylon 6 (Ultramid KR-4407F from BASF) and 2% of an antiblock agent (10853 from Ampacet).

These extrudates were joined in the arrangement described where they entered a coextrusion die. The resulting composite exited the die lips and was quenched, then wound into mill logs, and slit to the desired width using Dusenbury slitters.

The resulting laminate had an overall thickness of about 4.00 mils.

The sealant layer had a thickness of 1.16 mils or 29% of the overall laminate thickness. 7/900803.3/SPECFLDR 13 The LLDPE tie layer had a thickness of .32 mils or 8% of the overall laminate thickness.

The polyamide layers had thicknesses of .28 mils (adjacent the thicker adhesive layer) and .32 mils, representing 7% and 8% of the overall laminate thickness, respectively.

The core layer had a thickness of .40 mils or 10% of the overall laminate thickness.

The EVA based tie layer had a thickness of .92 mils or 23% of the overall laminate thickness.

The abuse layer had a thickness of .60 mils or 15% of the overall laminate thickness.

The sealant side of the laminate was corona treated to 50 dynes/cm.

EXAMPLE 2 A thermoformable cook-in laminate was prepared as described in Example 1, but with the first extruder providing a sealant layer comprising a blend of 5% EVA (LD-318.92 from Exxon which has a vinyl-acetate content of 9.0%), 93% LLDPE (Dowlex 2044A from Dow) and 2% of an antiblock agent (1085 3 from Ampacet).

EXAMPLE 3 A thermoformable cook-in laminate was prepared as described in Example 1, but with the first extruder providing a sealant layer comprising a blend of 15% ULDPE (Attane 4001 7/900803.3/SPECFLDR 14 'I § i from Bow), 83% LLDPE (Dowlex 2044A from Dow) and 2% of an antiblock agent (10853 from Ampacet).

EXAMPLE 4 A thermoformable cook-in laminate was prepared as described in Example 1, but with the first extruder providing a sealant layer comprising a blend of 15% ULDPE (Attane 4001 from Dow), 80% LLDPE (Dowlex 2044A from Dow) and 5% of an antiblock agent (10853 from Ampacet) and with the sixth extruder providing an abuse layer comprising 100% nylon 6 (Ultramid KR-4407F from BASF).

EXAMPLE 5 A thermoformable cook-in laminate was prepared as described in Example 1, but with the first extruder providing a sealant layer comprising a blend of 15% ULDPE (Attane 4001 from Dow), 83% LLDPE (Dowlex 2044A from Dow) and 2% of an antiblock agent (10853 from Ampacet) and with the sixth extruder providing an abuse layer comprising 100% nylon 6 (Ultramid KR-4407F from BASF).

EXAMPLE 6 A thermoformable cook-in laminate was prepared as described in Example 5 above but the sealant side of the laminate was not corona treated.

EXAMPLE 7 7/900803.3/SPECFLDR A thermoformable cook-in laminate is prepared as described in Example 1 above but with the first extruder providing a sealant layer comprising a blend of 15% LLDPE (Dowlex 2044A from Dow), 83% ULDPE (Attane 4001 from Dow), and 2% of an antiblock agent (10853 from Ampacet).

EXAMPLES 8-13 Thermoformable cook-in laminates were prepared as described above in Examples 1 - 7, respectively, but such that each laminate had an overall thickness of 6.0 mils, the percent of overall thickness of each layer being the same as described in Example 1.

EXAMPLES 14-19 Thermoformable cook-in laminates were prepared as described above in Examples 1 - 7, respectively, but such that each laminate had an overall thickness of 8.0 mils, the percent of overall thickness of each layer being the same as described in Example 1.

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. For example, the present sealing layer could be used in place of the sealing layer of any of the thermof ormable cook-in laminates disclosed herein. Accordingly, such modifications and variations may be practiced within the scope of the following claims. 7/900803.3/SPECFLDR 16

Claims (24)

1. A multiple-layer, cook-in laminate having a first food contacting and sealing layer comprising: from substantially 5% to substantially 95% by weight of li low density polyethylene; from substantially 5% to substantially 95% by weight of ethylene/alpha-olefin copolymers having a density of less than 0.915 g/cc; and from substantially 0% to substantially 2% by weight of an block agent.

2. The laminate of claim 1 wherein said food contacting and sealing layer is corona treated.

3. The laminate of claim 1 wherein said linear low density polyethylene comprises from substantially 80% to substantially 95% by weight of said food contacting and sealing layer and said ethylene/alpha-olefin copolymers having a density of less than 0.915 g/cc comprise from substantially 5% to substantially 20% by weight thereof.

4. The laminate of claim 1 wherein said laminate is selected as comprising at least the multi-layer laminate structure: first food contacting and sealing layer/barrier layer.

5. The laminate of claim 4 wherein said laminate is selected as comprising at least the multi-layer laminate structure: first food contacting and sealing layer/barrier layer/abuse layer.

6. The laminate of claim 1 further including additional layers comprising: a second or adhesive layer comprising a polyolefin based adhesive material; a third or polyamide layer; , . 7/900803.3/SPECFLDR 17 a fourth or barrier layer comprising ethylene vinyl alcohol; a fifth or polyamide layer; a sixth or adhesive layer comprising a polyolefin based adhesive material; and a seventh or abuse layer comprising a polyamide.

7. The laminate of claim 6 wherein the food contacting and sealing side thereof is corona treated within the ranae of from substantially 40 dynes/cm to substantially 60 dynes/cm.

8. The laminate of claim 7 wherein said food contacting and sealing side is corona treated to 50 avnes/cm.

9. The laminate of claim 6 wherein said third and fifth polyamide layers comprise nucleated nylon 6.

10. A multiple layer cook-in laminate comprising: a food contacting and sealing layer comprising a blend of linear low density polyethylene and other ethylene copolymers; a barrier layer; and an abuse layer comprising a polyamide.

11. The laminate of claim 10 wherein said other ethylene copolymers are ethylene/vinyl-acetate copolymers.

12. The laminate of claim 10 wherein said barrier layer comprises ethylene vinyl alcohol copolymer.

13. The laminate of claim 12 further including polyamide layers disposed on either side of said ethylene vinyl alcohol barrier layer.

14. The laminate of claim 13 wherein said polyamide layers comprise nucleated nylon 6.

15. The laminate of claim 13 further including intermediate layers disposed between the polyamide layer and 7/900803.3/SPECFLDR 2 5;.'.;. each of the food contacting and sealing layer and the abuse layer respectively and comprising an anhydride grafted polyolefin.

16. The laminate of claim 10 wherein the food contacting and sealing side thereof is corona treated to 50 dynes/cm.

17. A cook-in package having a food contacting layer comprising: from substantially 5% to substantially 95% by weight of linea low density polyethylene; from substantially 5% to substantially 95% by weight of ethylene/vinyl-acetate copolymers; and from substantially 0% to substantially 2% by weight of an antiblock agent.

18. The cook-in package of claim 17 wherein said food contacting layer is corona treated, for improved protein adhesion.

19. A method of making a cook-in film comprising: coextruding an inner sealing layer comprising from substantially 5% to substantially 95% by weight of linear low density polyethylene and from substantially 5% to substantially 95% by weight of other ethylene/alpha-olefin copolymers having a density of less than 0.915 g/cc, a barrier layer and an abuse layer comprising a polyamide; and quenching the coextruded film.

20. The method of claim 19 further including the step of corona treating the sealing layer.

21. A multiple-layer, cook-in laminate as claimed in any one of claims 1 to 16 substantially as hereinbefore described with reference to any example thereof and/or the accompanying drawing; -i ' 7/900803.3/SPECFLDR 19 ^ r , r, /L w' i \ w 1 -- . / i

22. A cook-in package as claimed in claim 17 or 18 substantially as hereinbefore described with reference to any example thereof and/or the accompanying drawing.

23. A method of making a cook-in film as claimed in claim 19 or 20 when performed substantially as hereinbefore described with reference to any example thereof ana/or the accompanying drawing.

24. A cook-in film when produced by a method as claimed in any one of claims.19, 20 and 23. 27 AUG 1991 received 20