Abstract:
A package for a microwaveable food product has a pair of sidewalls each having an inner layer formed of a generally microwave transparent material, and an outer layer formed of a generally non-microwave transparent material having high oxygen barrier properties. A layer of adhesive is disposed between the two layers, bonding the layer together in a peelable bond. The inner layers are positioned adjacent to each other and sealed together adjacent to the peripheral edges of the sidewall to thereby seal a microwaveable food product therein. Prior to heating, the non-microwave transparent outer layer is peeled off the sidewalls of the package.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a multi-layer package, with a peelable outer layer, for packaging food products intended for microwave heating.  
       BACKGROUND OF THE INVENTION  
       [0002]     The last decade has seen a great increase in the popularity of the use of packaged foods that are microwaved by the consumer prior to eating. The list of such foods is extensive and continually expanding. Appetizers, entrees, desserts and snacks all are included in this trend with products ranging from popcorn to pizza. Typically, these food items are stored in their packages from the time of their production until the time that they are later heated or cooked in a microwave oven.  
         [0003]     Some food products are relatively stable and their freshness easily maintained. Other food products present more of a challenge in maintaining their freshness, and thus require packaging having greater barrier properties. Depending upon their stability, microwavable food products have principally been packaged in one of three formats.  
         [0004]     A first format utilizes a low-barrier, but microwavable wrapper, which is adequate for many types of less sensitive foods. While this option utilizes packaging material which is the least expensive, it does not have adequate barrier properties to store more sensitive food products without resulting in poor taste, poor texture, poor appearance, or even spoilage of the food stored.  
         [0005]     A second more expensive packaging format is suitable for sensitive foods, and utilizes a high-barrier, but non-microwavable package. Food packaged using this format must be completely removed from its package prior to microwave heating. Thus, with this particular format the convenience of eating the heated food directly from the package is lost. Another drawback with use of this packaging format occurs when the food is to be heated in a microwave located in a public area, as may be the case for foods purchased at places such as a service station, convenience store or a fast food outlet. A consumer may be hesitant to completely remove the wrapper and then heat the bare food product in a public microwave of questionable or unknown cleanliness. Even when heating in a clean microwave oven, the exposed food product is prone to fouling the inside surfaces of the oven during heating or cooking, unless put into a separate closed container, that may or may not be available. Furthermore, many consumers prefer to eat a microwaved food product out of its original packaging, rather than heating in, and then eating from, a container that will later require cleaning.  
         [0006]     A third, still more expensive packaging format employs the use of a packaging material that provides high-barrier properties, as well as being capable of microwaving. This packaging format has the drawback of being relatively expensive, and the increased cost of the wrapper can adversely impact the profit margin of a food manufacturer. If the increased cost of the wrapper is passed on to the consumer, the higher price for the packaged items may reduce sales volume.  
         [0007]     Therefore, a need exists for a low cost microwaveable package which also has high-barrier properties.  
       BRIEF SUMMARY OF THE INVENTION  
       [0008]     In accordance of one aspect of the invention a package for a microwaveable food product is provided and has a first and second sidewalls . Each side wall is comprised of an inner layer formed of a generally microwave transparent material and an outer layer formed of a high oxygen barrier material. The inner layer has an inner surface and an outer surface with the inner surface of the inner layer of the first sidewall facing the inner surface of the inner layer of the second sidewall. The inner surfaces of the inner layers of the sidewalls are sealed adjacent the peripheral edges of the sidewalls to form a hollow interior for packaging a food product within the interior. The outer layer has an inner surface and a outer surface, the inner surface of the outer layer is positioned over the outer surface of the inner layer. An adhesive layer is positioned at least partially between the outer surface of the inner layer at the inner surface of the outer layer to peelably bond the outer layer to the inner layer. The bond is such that it allows manual removal of the outer layer. The microwaveable inner layer continues to package the food product during microwaving.  
         [0009]     In another aspect of the invention a package for packaging a microwaveable food product is provided having a flexible inner wrapper formed of a first generally microwave transparent material and a flexible outer wrapper formed of a high oxygen barrier and generally non-microwave transparent second material. The outer wrapper substantially surrounds the inner wrapper. The outer wrapper is attached to at least a portion of the inner wrapper by an adhesive layer. The outer wrapper is readily manually removable from the inner wrapper to allow removal of a substantial portion of the outer wrapper. The food product in the inner wrapper may then be heated by microwaving.  
         [0010]     In another aspect of the invention a multilayer packaging material is provided that has a first layer having a first surface and has a second layer having a second surface. An adhesive layer is disposed between the first surface and the second surface to at least partially bond the first layer to the second layer. The adhesive layer has a plurality of voids in the layer. The strength of the bond is such as to readily allow manual removal of the second layer from the first layer. The first layer is comprised of a substantially microwave transparent plastic material and the second layer is comprised of a high oxygen barrier substantially non-microwave transparent plastic material. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a cross sectional side view taken along line  1  of  FIG. 6  showing the package in accordance with the invention with a food product packaged therein;  
         [0012]      FIG. 2  is a cross sectional side view of the package of  FIG. 1  showing the outer layer partially peeled away from the inner layer;  
         [0013]      FIG. 3  is a cross sectional side view of the package of  FIG. 1  showing the outer layer fully peeled off the package;  
         [0014]      FIG. 4  is schematic drawing of the inner and outer layers and the adhesive layer there between;  
         [0015]      FIG. 5  is a cross sectional side view of the multilayer packaging material of the package;  
         [0016]      FIG. 6  is a perspective view of the package; and  
         [0017]      FIG. 7  is a perspective view of the package with manual separation of the outer layer from the inner layer being initiated. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]      FIG. 1  illustrates a package  10  for a food product  12  which includes an inner layer  14  and a peelable outer layer  16  and an adhesive  18  there between. Inner layer  14  is formed of a microwave transparent material such as, for example, a clear and sealable polypropylene or polyester. Outer layer  16  is formed of a non-microwave transparent high oxygen barrier material such as metalized polypropylene or metalized polyester. Microwave transparent layer  14  has an inner surface  20  adjacent food product  12  and an outer surface  22 . Adhesive  18  is applied to outer surface  22  of microwave transparent layer  14  and allows the inner surface  24  of outer barrier layer  16  to be peelably adhered to inner layer  14 . Preferably, the adhesive layer  18  is applied by spraying, laminating, or otherwise depositing onto outer surface  22 , a suitable adhesive material is, for example a peelable pressure-sensitive or other non-permanent laminating adhesive. Since it is desired that outer layer  16  be relatively easy to peel from inner layer  14 , it is advantageous not to completely cover outer surface  22  with adhesive. Thus a waffle-shaped configuration as shown in  FIG. 4 , or other patterns that provide voids or adhesive free spaces  32  in adhesive layer  18 , are preferred to facilitate manual separation of inner layer  14  and outer layer  16  at a later desired time. The voids may comprise at least one half of the area of adhesive layer  18 , or the adhesive may be applied in only a relatively limited number of spots on outer surface  22  of inner layer  14 .  
         [0019]     After application of adhesive  18  to inner layer  14 , layers  14 , 16  are joined together, such as by pressing the outer barrier layer  16  against the outer surface  22  of layer  14  to form the multilayer packaging material  26  of the present invention as seen in  FIG. 5 . As an example, layer  14  and layer  16  each may be individually provided in the form of a roll of stock (not shown). A machine (not shown) is utilized to simultaneously unroll each layer, while at the same time spraying the pattern of adhesive layer  18  onto outer surface  22  of microwave transparent layer  14 . The machine may then press layers  14 ,  16  together to form multilayer packaging material  26  that itself may be rolled up to provide a roll of stock of packaging material  26 . The roll of multilayer packaging material  26  can then be utilized in forming multilayered package  10  of the present invention. In the alternative, adhesive layer  18  may be formed on the inner surface  24  of high oxygen barrier layer  16  rather than outer surface  22  of layer  14 . It is also possible to spray adhesive onto both surfaces  22  and  24 , however this generally may not be preferred since to do so would tend to increase the force required to later peel layer  16  from layer  14 . It is also possible to form the adhesive layer as a distinct separate layer  18  which is positioned adjacent and then laminated onto the outer surface of layer  14 .  
         [0020]     Referring to  FIGS. 1 and 6 , sheets of packaging material  26  of a desired shape and size, for example a generally rectangular shape, are used to form the sidewalls  28  of package  10 . A pair of sidewalls  28  are arranged with inner surfaces  20  of inner layers  14  positioned face to face. The bottom ends  30  and the side edges  36  of the juxtaposed sidewalls  28  are sealed, such as by heat sealing, to form a package  10  that is closed at package bottom  34  and side edges  36 . At this stage of assembly, package  10  has an top end  38  that is open providing access to the interior  40  of package  10 . Food product  12  may then be inserted through top end  38  into interior  40  of package  10 . Top edges  42  of top end  38  are then sealed, such as by heat sealing opposing inner surfaces  20  of inner layer  14  along top edges  42  to form a closed hermetically sealed package  10 . To facilitate separation of outer layers  16  of sidewalls  28 , sidewalls  28  may have one or more portions  58  where outer layer  16  extends beyond top end  42  of inner layer  14  to allow easier griping of the outer layers  16  for separation. Since the top ends of inner layer  14  seal food product  14  within package  10 , if desired, outer layers  16  need not be sealed together at portions  58 .  
         [0021]     Other methods of packaging food product  12  will be readily apparent to those skilled in the art to meet the needs of various packaging applications. For example, food product  12  may be inserted between two sheets of multilayer packaging material  26  with the inner surfaces  20  of the inner layers  14  opposite each other. The bottom ends  30 , side edges  36  and top edges  42  may then be heat sealed, or otherwise adhered together, to enclose food product  12  within a sealed package  10 .  
         [0022]     Package  10  may also be thought as two separate flexible wrappers  50 , 52  each forming, in effect, a separate package, as can be best appreciated in  FIGS. 1-3 . Inner wrapper  50  is formed of two sheets of inner layer  14  and outer wrapper  52  is formed of two sheets of outer layer  16 . Alternatively, inner wrapper  50  and outer wrapper  52  may be formed separately and inner wrapper  50  inserted into outer wrapper  52 . Food product  12  can then be inserted into inner wrapper  50  and thereafter top edges  42  of inner wrapper  50  can be sealed to enclose food product  12 . Adhesive layer  18  between wrappers  50 ,  52  allows the outer wrapper  52  to be peelably attached to the inner wrapper  50 .  
         [0023]     As seen in  FIG. 7 , when it is desired that food product  12  in package  10  be microwave heated, the consumer manually peels back the outer high barrier layer  16  beginning at portions  58  from the inner microwave transparent layer  14 . To do so a user grips the outer layer  16  of one sidewall  28  at portion  58  with the users right thumb RT and right finger RF, and the other sidewall  28  at portion  58  in the users left thumb LT and left finger LF. Outer layers  16  of sidewalls  28  at portion  58  are then pulled apart. As seen in  FIG. 2  outer layers  16  are continued to be peeled away from inner layers  14  along sidewalls  28 . The peeling action is continued until outer layers  16  are entirely removed from package  10 , leaving only inner layers  14  of inner wrapper  50 . As seen in  FIG. 3  inner wrapper  52  retains food product  12  for microwave heating. Inner wrapper  50  remains sealed, if desired, during microwaving.  
         [0024]     After the food has been microwave heated, inner wrapper  50  consisting of inner layer  12  can be opened along top edges  42  and used for a container from which food product  12  is consumed. Or if desired, food product  12  may be removed from inner layers  14  and placed on another surface for serving.  
         [0025]     Thus, a higher barrier microwaveable multilayer food package  10  is provided that is capable of preserving relatively sensitive food products requiring barrier properties not available with lower cost microwaveable packaging materials. Moreover utilization of a high cost single material that is both a high oxygen barrier and microwaveable is avoided. Instead, the package of the present invention accomplishes its objective at a lower cost, providing high barrier properties and allowing microwaving through use of peelable high oxygen barrier outer layer  14  and microwaveable inner layer  12 .  
         [0026]     Where used in the various figures of the drawing, the same numerals designate the same or similar parts. Furthermore, when the terms “top,” “bottom,” “first,” “second,” “upper,” “lower,” “height,” “width,” “length,” “end,” “side,” “horizontal,” “vertical,” and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawing and are utilized only to facilitate describing the invention.  
         [0027]     Modifications may be made to the embodiments described above without departing from the broad inventive concepts thereof. Accordingly, the present invention is not limited to the particular embodiments nor to the theoretical description disclosed, but is intended to cover all modifications that are within the spirit and scope of the invention as defined in the appended claims.