Abstract:
A modified atmosphere package for storing oxygen sensitive goods containing a a gas impermeable tray including flanges around the perimeter of the tray and a bottom inside surface, and a a gas impermeable film with a bottom inside surface. The film is fitted with a one-way valve and is positioned over and adjacent to the flanges of said tray, and the film is sealed to such flanges. A support extends from the bottom inside surface of the tray to the bottom inside surface of the gas impermeable film, the support being adapted to prevent the film from collapsing when the atmospheric pressure above the film exceeds the atmospheric pressure below the film.

Description:
CROSSED-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a continuation-in-part of applicant&#39;s patent application U.S. Ser. No. 09/182,754, filed Oct. 29, 1998, U.S. Pat. No. 6,023,915 which relied for priority upon provisional patent application 60/094,694, filed May 8, 1998. 
    
    
     FIELD OF THE INVENTION 
     A modified atmosphere package for storing oxygen sensitive goods which contains internal means for supporting such package. 
     BACKGROUND INVENTION 
     Applicant&#39;s copending patent application U.S. Ser. No. 09/182,754 describes and claims a modified atmosphere package for storing oxygen-sensitive goods. The package of the instant application is an improvement over the package of applicant&#39;s prior case, containing means for supporting the gas impermeable film used in the package. When vacuum is applied to such package, the film often tends to collapse, causing the package to have a less desirable appearance. The package of this case is as desirable as applicant&#39;s prior package and, additionally, is not subject to being collapsed as readily by the application of vacuum. 
     It is an object of this invention to provide a flexible, low cost apparatus for establishing a variety of modified atmospheric conditions within a package containing a food or non-food product. 
     SUMMARY OF THE INVENTION 
     In accordance with this invention, there is provided a modified atmosphere package for storing oxygen sensitive goods, comprising: a gas impermeable tray including flanges around the perimeter of said tray, and a gas impermeable film fitted with a first one-way valve, said film positioned over and adjacent to said flanges of said tray, said film is sealed to said flanges of said try forming said package, and wherein such package contains means disposed within the package for supporting said gas impermeable film. 
    
    
     BRIEFED DESCRIPTION OF THE DRAWINGS 
     The present invention will be more fully understood by reference to the following detailed description thereof, when read in conjunction with the attached drawings, wherein like reference numerals refer to like elements, and wherein: 
     Each of FIGS. 1,  2 ,  3 ,  4 ,  5 ,  6 ,  7 ,  8 ,  9 ,  10 ,  11 ,  12 ,  13 ,  14 ,  15 , and  16  is a sectional view of one embodiment of the package of this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a sectional view of one preferred embodiment of the invention. Referring to FIG. 1, it will be seen that barrier film tray package  10  includes a gas impermeable tray  12  to contain oxygen sensitive food or non-food goods  15 ; such goods can include, e.g., meat, fish, poultry, prepared meals, non-food items, etc. A gas impermeable film or lid  18  is positioned over the goods and the tray  12 . 
     In the embodiment depicted in FIGS. 1,  2 ,  3 ,  4 ,  5 ,  6 ,  7 , and  8 , the gas impermeable film  18  is fitted with a one-way valve  20 . In the embodiment depicted in FIGS. 9,  10 ,  11 ,  12 ,  13 ,  14 ,  15 , and  16 , the one-way valve is disposed in either the bottom of gas impermeable tray  12 , or on the side of gas impermeable tray  12 . 
     Referring again to FIG. 1, and in the preferred embodiment depicted therein, the tray package  10  is disposed within a vacuum chamber  16 , and vacuum is imposed through port  17  so that gas flows from the interior of chamber  16  in the direction of arrow  19 . This vacuum causes valve  20  to open, allowing air within tray  12  to escape into chamber  16  and thence out of port  17 . 
     When one ceases imposing a vacuum through port  17 , the valve  20  eventually closes, thereby maintaining a vacuum within tray  12 . When this occurs, the atmospheric pressure outside on top of film  18  is greater than the pressure below film  18 , and film  18  will then tend to collapse in the direction of arrow  21 . When this occurs, goods  15  tend to be contacted by the collapsing film  18  and/or compressed; often this collapsing film damages the goods; and, at the very least, the collapsing film tends to give the package a poor appearance. 
     In the embodiment depicted in FIG. 1, one or more supports  13  are disposed within the tray  12  and are contiguous with the bottom inside surface  23  of tray  12  and the top inside surface  25  of film  18 . 
     In the embodiment depicted in FIG. 1, only one support  13  is shown for the sake of simplicity of representation. It is preferred that each tray  12  contain at least 2 of these supports  13  and, preferably, at least 3 of these supports  13 . In one embodiment, tray  12  contains at least 4 of these supports  13 . 
     The supports  13  generally have a thickness  27  of from about 0.020 to about 0.500 inches. In one embodiment, support  13  has a thickness of from about 0.1 to about 0.3 inches. 
     In one embodiment, the support(s)  13  are integrally connected to tray  12 . In another embodiment, the support(s)  13  are adhesively connected or otherwise bonded by conventional means to the bottom surface  23  of tray  12 . 
     In one embodiment, the support(s)  13  consist essentially of plastic material. 
     In one embodiment, support(s)  13  are in the form of a ring which is contiguous with but not necessarily bonded to the bottom of tray  12 . Many other embodiments of support(s)  13  will be apparent to those skilled in the art; all are within the scope of this invention. 
     The surfaces of the flanges  14  of the tray  12  and the edges of the film  18  are sealed to prevent gases from escaping the interior of the package  10 . The gas escaping the valve  20  in the film  18  can be monitored to determine when the appropriate modified atmosphere levels have been reached within the package  10 . With this configuration, the need for solid carbon dioxide and/or an oxygen absorber is not required. 
     The package  10  can also be used in microwaveable applications, since the pressure within the package  10  is self-venting. Unlike existing food packages, the top of the package  10  does not have to be peeled back or the contents removed from the package or holes punched in the film. The package  10  can be placed directly into the microwave oven. As pressure builds inside the package  10 , the one-way valve  20  on the top of the tray  12  will vent, allowing the gas to escape. 
     The tray  12  can be constructed of a thermoformable monolayer structure of polyester (such as amorphous poly[ethylene terephthalate]), or polyvinyl chloride. The total thickness of the material prior to thermoforming is from about 0.010 to about 0.030 inches. The tray  12  can be made of gas permeable or substantially gas impermeable materials. In one embodiment, the tray material is dense enough to prevent seepage of liquid. 
     One may utilize absorbent trays, such as those supplied by Vitembal (France) or Linpak (U.S./Europe). Alternatively, one may use other means, such as an absorbent pad, for absorbing liquids exuded from meat. 
     The tray may consist essentially of polyolefins (such as polypropylene/polyvinylidene chloride/polypropylene, with ties layers between the polypropylene and the polyvinylidene chloride), high density polyethylene, polyvinylidene chloride/high density polyethylene with tie layers between the high density polyethylene and the polyvinylidene chloride, and the like. 
     The tray may be constructed of a plastic foam (open celled or closed celled), such as polystyrene, polypropylene, polyvinyl chloride, and polyester; and it may include a substantially gas impermeable plastic layer laminated thereto or any combination of plastic, paper, glass, aluminum or coatings, coextrusions or laminations of such materials such that the combination contemplated provides a barrier to oxygen permeation equal to or less than 0.55 cc-mil per 100 square inches per day in ambient atmosphere at one atmosphere pressure. 
     In one embodiment, the laminated barrier layer is manufactured from a co-extruded LLDPE/polyvinylidene chloride/LLDPE structure with tie layers between the LLDPE and polyvinylidene layers and with a thickness of from about 0.003 to about 0.006 inches. Alternatively, the tray may be constructed of a polyamide (such as nylon), a coextruded nylon/EVOH structure laminated to a LLDPE or LLDPE/LPDE heat sealable layer with tie layers between the nylon and EVOH layers, said structure being commercially available from Allied Specialty Films in the United States. 
     FIG. 2 is a sectional view of a tray package  10  which is comprised of solid carbon dioxide  99 . In general, from about 10 to about 150 grams of carbon dioxide  99  is present, generally at a temperature of less than about −60 degrees Fahrenheit. 
     It is preferred that the solid carbon dioxide not be contiguous with the oxygen-sensitive goods  15  but, instead, be contiguous with tray  12 . 
     As will be apparent to those skilled in the art, as air is removed through valve  20  upon the imposition of vacuum through port  17 , the solid carbon dioxide sublimes and fills the tray  12  with gaseous carbon dioxide. The sublimation generally is slower than the evacuation; and, thus, the support  13  is essential for preventing the film  18  from collapsing. 
     In one embodiment, air is evacuated from tray  12  at a rate of at least about 0.1 liters per second when the vacuum is imposed through port  17 . 
     In the embodiment illustrated in FIG. 3, instead of using solid carbon dioxide within tray  12  (see FIG.  2 ), an oxygen-absorber  97  is used. These oxygen absorbers are well known to those skilled in the art. Thus, for example, in U.S. Pat. No. 5,698,250 of Gary R. DelDuca et al., which is assigned to Tenneco Packaging Inc., a “modified atmospheric package” was claimed. This package contained “. . . an oxygen scavenger activated with an activating agent . . . .” According to the patentees, the oxygen scavenger is necessary because “Low-level oxygen systems relying upon evacuation techniques to diminish oxygen levels suffer from several disadvantages . . . the evacuation techniques render it difficult to remove any oxygen within a previously wrapped package such as an overwrapped meat tray . . . . The trapped oxygen raises the residual oxygen level in the package and can also cause billowing and subsequent damage to the package during evacuation” (see lines 3-15 of column 2 of this patent). The entire disclosure of this patent is hereby incorporated by reference into this specification. Furthermore, each of the prior art references cited during the prosecution of this patent are also hereby incorporated by reference into this specification. 
     FIG. 4 is a sectional view of a package  10  which contains both an oxygen-absorber  97  and solid carbon dioxide  99 . 
     FIG. 5 illstratews an embodiment with neither the oxygen-absorber  97  or the solid carbon dioxide  99 , and with only one valve  20 . 
     FIG. 6 illustrates a tray  10  similar to that depicted in FIG. 5 but which contains solid carbon dioxide  99 . FIG. 7 illustrates a tray  10  similar to that depicted in FIG. 5 but which also contains oxygen scavenger  97 . FIG. 8 illustrates a tray  10  similar to that depicted in FIG. 8, but which also contains solid carbon dioxide  99 . 
     FIG. 9 illustrates a tray assembly  10  with a valve  20  located either in the bottom  95  of the tray assembly or in the sidewall  93  of the tray assembly. In this embodiment, only one valve  20  is preferably used, in either of the designated locations. FIG. 10 illustrates a tray assembly  10  similar to that illustrated in FIG. 9 but which also contains solid carbon dioxide  99 . FIG. 11 illustrates a tray assembly similar to that illustrated in FIG. 9 but which also contains an oxygen-scavenger  97 . FIG. 12 illustrates a tray assembly similar to that depicted in FIG. 10 but which also contains an oxygen-scavenger  97 . 
     FIG. 13 illustrates a tray assembly  10  in which the perishable goods  15  are contiguous with both the bottom  23  of tray 12  as well as the bottom surface  25  of film  18 . As will be apparent to those skilled in the art, in this embodiment the oxygen-sensitive goods  15  acts as a support in place of support  13  (see FIG.  1 ). FIG. 14 illustrates a tray assembly similar to that depicted in FIG. 13 but which also contains solid carbon dioxide  99 . FIG. 15 illustrates a tray assembly  10  similar to that depicted in FIG. 13 but which also contains oxygen scavenger  97 . FIG. 16 illustrates a tray assembly similar to that depicted in FIG. 14 but which also contains an oxygen scavenger  97 . 
     The one-way valve  20  may be, e.g., the one-way valve produced by Plitek LLC of Des Plaines, Ill. 
     It is to be understood that the aforementioned description is illustrative only and that changes can be made in the apparatus, in the ingredients and their proportions, and in the sequence of combinations and process steps, as well as in other aspects of the invention discussed herein, without departing from the scope of the invention as defined in the following claims.