WO1998017546A1

WO1998017546A1 - Package having peel initiation mechanism

Info

Publication number: WO1998017546A1
Application number: PCT/US1997/016973
Authority: WO
Inventors: James R. Mabry
Original assignee: Cryovac, Inc.
Priority date: 1996-10-18
Filing date: 1997-10-16
Publication date: 1998-04-30
Also published as: AR013848A1; AU4801797A

Abstract

A package (10) which allows for butchering and packaging of fresh red meat at a centralized facility is provided which includes a composite support member (12) such as a barrier foam tray for receiving and supporting the meat, a permeable film enclosing the meat and an impermeable film enclosing the permeable film which remains in place during distribution and is removed at retail. The impermeable film is sealed to a sealing surface (22) on the flange of the tray. A lip (24) is positioned below the sealing surface and provides a peel initiation point for removing the impermeable film at retail with reduced package failure.

Description

PACKAGE HAVING PEEL INITIATION MECHANISM

Background of the Invention The present invention relates generally to packages for fresh red meat. Particularly, this invention is directed to the packaging of food products such that the packaged product may be maintained in one condition under certain circumstances and then converted to another condition. Specifically, packages in accordance with the present invention provide for distribution of a packaged product in a low oxygen environment and for introduction of oxygen to the product surface at a supermarket or other retail outlet. While a wide variety of food products can be packaged in accordance with the teachings of this invention, it is particularly advantageous in connection with the packaging of fresh red meat such that the meat may be transported in a low oxygen atmosphere, that is, preferably 0.5% O₂ or less, and then caused to bloom when it reaches a supermarket by exposure to oxygen.

Historically, large sub-primal cuts of meat have been butchered and packaged in each supermarket. It has long been recognized that this arrangement is extremely inefficient and expensive. Instead it would be preferable to permit the meat to be butchered and packaged at a central facility which benefits from economies of scale and thereafter shipped to individual supermarkets such as is done, for example, with many poultry products.

In the past, the goal of central fresh red meat processing has not been achievable because most consumers prefer to buy meat which is reddened in color as a result of exposure to oxygen. However, the meat maintains its reddened color for approximately one to two days and, thereafter, turns a brown color which is undesirable to most consumers. Therefore, if the meat was butchered and packaged in a gas permeable film, as is typical at retail, at a central location and then shipped to another location for eventual sale, in all likelihood, by the time the package reached the retail outlet the meat would have undergone the transformation to the brown color and would be effectively unsalable. Conversely, if the meat was butchered and packaged in a gas impermeable film at a central location and then shipped to another location for eventual sale, the meat would reach the retail outlet having a purple color which is typical of meat prior to exposure to oxygen. Heretofore, marketing efforts to teach the consumer about the harmlessness of the purple color have proved to be ineffective. And, if the gas impermeable film was a component of a conventional package having a tray which is overwrapped or lidded with a film, the impermeable film would have to be removed and replaced with a permeable film in order to allow for bloom of the meat to a bright red color prior to display for the consumer, negating to a large extent the benefits of a central processing facility. A variety of packages have been developed in an effort to provide a means for transporting meat in a low oxygen environment and for quickly and easily introducing oxygen to the meat at the retail outlet immediately prior to display to the consumer.

One approach to solving this problem has involved the development of peelable films. That is, films have been developed which readily delaminate into permeable and impermeable portions. Such a film is sealed to a support member, such as a tray, which contains the meat product, thereby forming a gas impermeable package for distribution. At the retail outlet, the gas impermeable portions are peeled from the film leaving a permeable film sealed to the tray and, therefore, a gas permeable package which allows the meat to bloom to bright red. Most of the other approaches to achieving the goal of central fresh red meat processing have involved the development of a variety of dual web packages of the type having a permeable film covering the meat product and an impermeable film, which is removed at the retail outlet, covering the permeable film wherein the permeable film and the impermeable film are separate, discreet films. Examples of these types of packages include dual overwrap packages wherein a permeable film is wrapped around the meat and its support member and an impermeable film is wrapped about the permeable film, dual lid packages which include a permeable lid and an impermeable lid sealed to the periphery of the support member, and packages with a head space which allows for the introduction of a treating gas, typically nitrogen, carbon dioxide or some mixture of the two, between a permeable film adjacent to the meat product and an impermeable upper web. For the latter two types of packages, the support member must have oxygen barrier properties as the impermeable film does not extend completely around the package.

Such impermeable support members may generally be chosen from a variety of commercially available designs and compositions, and generally include a tray with a sealant material bonded to the innermost and uppermost surfaces thereof. The sealant material generally serves both as a material to which a lidding film can be sealed and also as a material which provides a barrier to the passage of oxygen into the tray. Examples of commercially available trays include those which are formed of a rigid solid polymer, a barrier/sealant coated polymer, a barrier/sealant coated foamed polymer, or barrier/sealant coated pulp or paperboard. For foamed trays, an oxygen impermeable/sealant film must be included, at least, on the innermost and uppermost surfaces of the tray in order to prevent the ingress of oxygen into the package and to allow a lidding film to be sealed to the tray. One readily available support member is a foamed substrate of a resin such as polystyrene or polypropylene with a sealant film laminated thereto. The oxygen impermeable/sealant film must be capable of forming a seal, preferably a heat seal, with the permeable film and, in a dual lid package, the impermeable film. In order to prevent outgassing of residual gases from the foamed structure into the package and in order to maintain a low oxygen atmosphere within the package prior to removal of the upper impermeable film, the sealant film must also be an oxygen impermeable film. A tray formed from such a film/foam laminate is generally referred to as a "barrier foam tray."

Therefore, the film/foam laminate from which the support member is produced is formed by extruding a foamed sheet, extruding a sealant film, and laminating the two together. The laminate is then thermoformed and cut into a plurality of support members, commonly referred to as barrier foam trays. At the cut edge of each tray it is possible to view the film/foam laminate in cross-section. For some trays, another film laminated to the opposite side of the foamed sheet is employed to form a film/foam/film laminate. Hereagain, such three-layer laminate is discernible at the cut edge of each tray made therefrom.

For packages having a permeable film sealed to an inner portion of a barrier foam tray flange which is covered by an impermeable film sealed to an outer portion of the barrier foam tray flange a problem has arise when an attempt is made, at retail, to peel the impermeable film from the package. That is, if the impermeable film is sealed to the outer portion of the tray flange all the way to the cut edge of the tray, when an attempt is made to peel the impermeable film away from the tray, the retail worker often, instead, pulls the sealant film from the foam, either delaminating the tray into its separate film and foam components or tearing apart the foam, and, either way, causing a package failure. Such package failure occurs even though the force required to peel the impermeable film from the tray is much less than either the force required to pull the sealant film from the underlying foam or the force required to cause cohesive failure of the foam such that portions of the foam are pulled up with the sealant film. Rather, the failure occurs because the retail worker inadvertently grips and pulls the sealant film when attempting to peel the impermeable film from the tray.

SUMMARY OF THE INVENTION The present invention provides a package comprising a support member or tray comprising a base, sidewalls extending upwardly therefrom, and a flange. The flange comprises at least one sealing surface extending about a perimeter thereof and a lip adjacent and exterior to the at least one sealing surface and positioned below the sealing surface. The sidewalls have an innermost surface and the base, sealing surface and lip have an uppermost surface. A sealant material is bonded to the innermost surface of the sidewalls and on the uppermost surfaces of the base, sealing surface, and lip. A product is positioned within the support member and a film is sealed to the support member at the at least one sealing surface of the flange thereby enclosing the product. The film extends outwardly from the at least one sealing surface and is not sealed to the lip.

In accordance with another aspect of the invention, a package includes a support member comprising a base, sidewalls extending upwardly therefrom, and a flange. The flange comprises a first, interior sealing surface and a second, exterior sealing surface, each of the sealing surfaces extending about separate perimeters of the flange. The flange further comprises a lip adjacent and exterior to the second sealing surface and is positioned below the sealing surface. The sidewalls have an innermost surface and the base, first and second sealing surfaces, and lip have an uppermost surface. A sealant material is bonded to the innermost surface of the sidewalls and on the uppermost surfaces of the base, first and second sealing surfaces, and lip. A product is positioned within the support member and a first, permeable film is sealed to the support member at the first interior sealing surface of the flange to thereby enclose the product. A second, impermeable film is peelably sealed to the support member at the second, exterior sealing surface of the flange to thereby enclose the permeable film. The impermeable film extends outwardly from the second, exterior sealing surface and is not sealed to said lip. Advantageously, packages in accordance with the present invention allows for central processing of fresh red meat with minimal package failure at retail. This is accomplished by providing a peel-initiation lip on the support member which allows the outer, impermeable film of a dual lid package, or the impermeable portion of a delaminatable film of a single lid package, to be peelably removed from the support member at retail. The peel-initiation lip minimizes the liklihood that the retail worker will inadvertently grip and pull the sealant film bonded to the support member when attempting to remove the impermeable film.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of preferred embodiments of the invention follows, with reference to the accompanying drawings, wherein:

Fig. 1 is a perspective view of a package, according to the invention;

Fig. 2 is an enlarged view of the cut edge of the tray of the package of Figure 1 ; Fig. 3 is a cross-sectional view of the package of Figure 1;

Fig. 4 is a cross-sectional view of the package of Figure 1 as is shown in Figure 3 with the impermeable film being peeled from the tray;

Fig. 5 is a cross-sectional view of another package in accordance with the present invention; Fig. 6 is a cross-sectional view of the package of Figure 5 with the impermeable portion of the multilayer film being peeled from the permeable portion; and

Fig. 7 is an enlarged view of the flange of the package of Figures 5 and 6 demonstrating the delamination mechanism of the multilayer film.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention generally relates to a package for products, particularly fresh red meat products, having a support member or tray, and a film sealed about a peripheral flange of the tray.

Most typically, the support member of the present invention is a barrier foam tray as discussed above. However, all composite trays which are formed of multilayer laminated or coextruded materials and which are subject to delamination or cohesive failure are within the scope of the present invention. Examples of composite support members within the scope of the present invention are trays formed of polymeric or paperboard substrates having a sealant film laminated thereto, trays formed of substrates having a sealant layer coated thereon, and trays formed from multilayer, coextruded sheets having an outer sealant layer. Although the present invention is generally directed to a package having a product contained within such a tray with a lidding film sealed to the flange of the tray, it is specifically directed to a package for products, particularly fresh red meat products, having a composite tray, an inner permeable film sealed to the flange of the tray, and an outer impermeable film sealed either to flange of the tray or to the permeable film. However, the peel initiation mechanism provided by the present invention may be advantageously employed on any package having a lidding film peelably sealed to a composite tray such that the lidding film may be easily removed by peeling it from the tray. However, it is of particular importance to packages which must maintain package integrity for a period of time following removal of one of two top films. For the centrally-packaged fresh red meat package discussed above, package failure which occurs during removal of the outer, impermeable film results in product failure, not merely an inconvenient opening mechanism. Thus, while the present invention is generally directed to a package having a film sealed to a single sealing surface on the flange of a tray, it is particularly directed to a package having one, preferably permeable film sealed to a first sealing surface of the flange and another, preferably impermeable film sealed either to a second sealing surface of the flange or to the permeable film itself.

The permeable film of the present invention is an oxygen permeable or non-barrier film which may be a formable or stretchable material. Typical polymeric materials for the present permeable film may include any material which may be securely sealed or bonded to the support member and which provides a sufficient gas permeability as discussed above.

Generally, olefinic polymers are preferred and most preferred are ethylenic polymers such as polyethylene or any of a variety of ethylene copolymers including, for example, ethylene vinyl acetate, ethylene acrylate copolymers, ethylene acrylic acid copolymers including metal neutralized salts thereof, and ethylene alpha-olefin copolymers. Such ethylene alpha-olefins may be heterogeneous or homogeneous in nature. That is, ethylene alpha-olefins which have been formed by conventional Zeigler-Natta catalysis and are heterogeneous in nature, such as linear low density polyethylene (LLDPE), are within the scope of the present invention as well as such copolymers which are formed by single site catalysis, such as any of a variety of forms of metallocene catalyst technology, and are homogeneous in nature are also within the scope of the present invention. A preferred permeable film for use in accordance with the present invention is a symmetrical, five layer oriented film having the structure:

EVA / LLDPE / EVA / LLDPE / EVA although a wide variety of permeable films may be employed.

The impermeable film of the present invention may be any suitable barrier film or laminate which is substantially impermeable to gas such as oxygen so that a fresh meat product contained in a vacuum or other low oxygen atmosphere possesses an enhanced shelf life over a package without the barrier layer. Suitable polymeric materials having gas barrier properties for use in the present invention include ethylene vinyl alcohol copolymers, vinylidene chloride copolymers (PVDC) such as vinylidene chloride vinyl chloride or vinylidene chloride methyl acrylate. Laminates of a sealable film and a barrier structure which includes a barrier layer and a tough, non-forming material such as a biaxially oriented nylon or biaxially oriented polyester are especially preferred for use as the impermeable lidding of the present inventive package. An exemplary film structure for the impermeable web is polyamide/tie/polyamide/EVOH/polyamide/tie/LLDPE/LLDPE and/or EVA (where "tie" is a tie or adhesive layer). Such film is preferably cast-coextruded. An alternative film structure is a saran-coated, biaxially-oriented polyamide film adhesively laminated to the following coextruded film: EVA/LLDPE PE and/or PP and/or EVA.

Generally, the films which may be employed in accordance with the present invention may be monolayer or multilayer. Multilayer films may be employed when all of the properties required of the film cannot be achieved by a single polymeric component or a blend of polymers in a single layer. For example, an impermeable film to be sealed to a tray in all likelihood will comprise a multilayer film because several properties are needed including peelable sealability, oxygen barrier, and impact and/or outer abuse properties. Thus, the film employed will most likely contain three layers at a minimum: a seal layer, a barrier layer, and an outer abuse layer. Further internal layers such as adhesive layers and bulk layers may also be included. Laminates of sealable films and nonforming materials such as biaxially oriented polyester or biaxially oriented nylon are also within the scope of the present invention and are widely recognized as superior lidstocks for tray-type packages.

Generally, films in accordance with the present invention will be extruded or coextruded through either a slot die or an annular die forming either a sheet or a tube, respectively. While the extruded polymeric material is still in a molten state the sheet or tube may be expanded by stretching or blowing to achieve a desired dimension. The film is then cooled, slit to desired widths and taken up as a roll. Such rolls of film are employed in the packaging process as is discussed in greater detail below.

Figure 1 shows a package 10 in accordance with the present invention having a composite tray or support member 12 with a cavity 14 defined by base 7 and sidewalls 9 for receiving a product 16 and an upper flange 18 which includes inner sealing surface 20, outer sealing surface 22, and lip 24. Tray 12 has been thermoformed from a three layer composite material having an upper sealant film 11, foam core 13, and outer film 15 and cut at edges 17. Figure 2 provides an enlarged view of edge 17. From Figures 3 and 4 it may be discerned that sealant film 11 is bonded to the uppermost surface of base 7, the innermost surfaces of the sidewalls 9, inner sealing surface 20, outer sealing surface 22, and the uppermost surface of the lip 24.

As is shown in Figure 3, impermeable film 26 is sealed to the support member at outer sealing surface 22. A peelable seal is formed between the impermeable film 26 and outer sealing surface 22 such that the outer impermeable film may be readily removed from the package at retail. As is shown in Figure 3, film 26 extends beyond outer sealing surface 22. Lip 24 extends downwardly from outer sealing surface 22 such that film 26 may be readily grasped for ease of removal. Figure 4 shows film 26 being removed with underlying permeable film 24 sealed to inner sealing surface 20 and with composite tray 12 remaining intact.

Although less preferred, a tray having non-stepped sealing surfaces may be employed in the present invention so long as the impermeable film seal is formed external to the permeable film seal and the lip is stepped down from the external sealing surface. Such non- stepped flange may include those of the type having an inner sealing surface, a coplanar outer sealing surface, and a downwardly extending groove separating the two wherein the groove provides for easy cutting of the permeable film following sealing to the first inner sealing surface. However, trays having a single sealing surface wherein the permeable film may be sealed interior to the impermeable film seal are also within the scope of the present invention.

Another embodiment in which a tray having such a single sealing surface may be advantageously employed is illustrated in Figures 5 - 7. Figure 5 shows a package 110 in accordance with the present invention having a composite tray or support member 112 with a cavity 114 defined by base 107 and sidewalls 109 for receiving a product 116 and an upper flange 118 which includes sealing surface 120 and lip 124. Tray 112 has been thermoformed from a three layer composite material having an upper sealant film 111, foam core 113, and outer film 115 and cut at edges 117. Film 126 is sealed to the support member at sealing surface 120. Film 126 extends beyond sealing surface 120 and lip 124 extends downwardly from sealing surface 120 such that film 126 may be readily grasped.

As is shown in Figure 6, film 126 is a multilayer, coextruded film which is capable of delaminating into a permeable portion 130 and an impermeable portion 132. The force required to delaminate upper, impermeable portion 132 from lower, permeable portion 130 is much less than the force required to break the seal between the film and sealing surface 120 such that grasping and pulling film 126 delaminates the film, leaving permeable portion 130 sealed to sealing surface 120, rather than peeling the entire film from the tray.

Figure 7 shows in greater detail the mechanism by which film 126 delaminates. That is, when the retail worker initially grasps and pulls on film 126 the entire structure, including permeable portion 130 and impermeable portion 132 is being pulled. When the pulling pressure reaches the seal between the film and sealing surface 120 the film begins to rupture until the weak layer-to-layer interface is reached between permeable portion 130 and impermeable portion 132. A variety of multilayer film structures are useful in accordance with the present embodiment and are capable of such delamination. All include gas permeable polymeric materials in one or more layers in the permeable portion of the film, a gas barrier polymer layer and possibly other polymeric layers in the impermeable portion of the film, and a layer-to-layer interface between the two portions which is readily delaminatable. Also within the scope of the present invention are laminates of permeable and impermeable films which are capable of such inter-film delamination. The foregoing description of preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents.

Claims

WHAT IS CLAIMED IS:

1. A package comprising: a support member comprising a base, sidewalls extending upwardly therefrom, and a flange, said flange comprising at least one sealing surface extending about a perimeter thereof and a lip adjacent and exterior to said at least one sealing surface and positioned below said sealing surface, wherein said sidewalls have an innermost surface and said base, sealing surface and lip have an uppermost surface; a sealant material bonded to the innermost surface of said sidewalls and on the uppermost surfaces of said base, sealing surface, and lip; a product positioned within said support member; and a film sealed to said support member at the at least one sealing surface of the flange thereby enclosing the product, said film extending outwardly from the at least one sealing surface and not sealed to said lip.

2. The package set forth in claim 1 wherein the film is peelably sealed to said support member at the at least one sealing surface.

3. The package set forth in claim 1 wherein the film is a multilayer film, capable of delamination into a permeable portion and an impermeable portion.

4. The package set forth in claim 3 wherein the multilayer film is sealed to said at least one sealing surface at said permeable portion.

5. The package set forth in claim 4 wherein the force required to delaminate said multilayer film is less than the force required to remove the multilayer film from the at least one sealing surface.

6. The package set forth in claim 1 wherein the uppermost surface of the lip of the flange is parallel to and below the at least one sealing surface.

7. The package set forth in claim 1 wherein the sealant material is a sealant film.

8. The package set forth in claim 7 wherein the sealant film is an oxygen- impermeable film.

9. The package set forth in claim 1 wherein said support member comprises a film/foam laminate.

10. The package set forth in claim 1 wherein said support member comprises a film/foam/film laminate.

11. A package comprising: a support member comprising a base, sidewalls extending upwardly therefrom, and a flange, said flange comprising a first, interior sealing surface and a second, exterior sealing surface, each of said sealing surfaces extending about separate perimeters of said flange, said flange further comprising a lip adjacent and exterior to said second sealing surface and positioned below said sealing surface, wherein said sidewalls have an innermost surface and said base, first and second sealing surfaces, and lip have an uppermost surface; a sealant material bonded to the innermost surface of said sidewalls and on the uppermost surfaces of said base, first and second sealing surfaces, and lip; a product positioned within said support member; a first, permeable film sealed to said support member at the first interior sealing surface of the flange thereby enclosing the product; and a second, impermeable film peelably sealed to said support member at the second, exterior sealing surface of the flange thereby enclosing the permeable film, said impermeable film extending outwardly from the second, exterior sealing surface and not sealed to said lip.

12. The package set forth in claim 11 wherein the uppermost surface of the lip of the flange is parallel to and below the first and second sealing surfaces.

13. The package set forth in claim 11 wherein the second sealing surface is parallel to and below the first sealing surface.

14. The package set forth in claim 11 wherein the sealant material is a sealant film.

15. The package set forth in claim 11 wherein the sealant film is an oxygen- impermeable film.

16. The package set forth in claim 11 wherein said support member comprises a film/foam laminate.

17. The package set forth in claim 11 wherein said support member comprises a film/foam/film laminate.