Abstract:
A bacon package has a stiffener sheet formed of plastic having an inner layer of foam polystyrene and solid films of polystyrene on opposite sides of the foam layer and coextruded therewith to form a web. The web of coextruded plastic is fed through an embossing station which forms an embossment defining the outer periphery of the stiffener sheet and, if desired, a plurality of annular embossments within the periphery. The embossed extrudate is then cut with heated knives around each embossment to seal the edges defined by the embossments. Apparatus other than heated knives may be used for sealing the edges.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is based on and claims the benefit of provisional application No. 60/727,775 filed Oct. 18, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a new and improved package for bacon and to a stiffener board for use therein. The package of the present invention has a number of advantages over the present paper board product used for packaging bacon. The bacon package presently on the market uses a wood fiber board material that is laminated on both the upper and lower surfaces with a plastic sheet. The lower surface is pigmented (black, yellow, or other color). The upper film is either printed on the top surface or reversed printed to show through the clear film of the lamination. The package is finished by punching the perimeter and a number of windows to allow the marble of the bacon to show through for observation by the customer.  
         [0003]     The laminated and printed board is folded around the bacon and the total package is then vacuum sealed with a clear film.  
         [0004]     The use of fiber board in the present packages for bacon leads to a number of problems that the present invention solves.  
         [0005]     The problems with the prior packages include:  
         [0006]     The fibers in the edge of the board sometimes poke through the vacuum shrink film allowing air to enter the package. If this happens on the packing line, the bacon can be recycled and the value saved. If the leak is missed by the packer or is a slow leak that shows up at the retailer, the retailer will not accept it and the bacon must be destroyed.  
         [0007]     The bacon grease also soaks into the fiber board at the cut edges. The soaking in of the grease makes the package soggy.  
         [0008]     The grease together with the organic fiber produces sites for mold or bacteria growth.  
         [0009]     Fibers and paper dust from the cut can find its way to the surface of the bacon.  
         [0010]     The films delaminate from the base board.  
         [0011]     These problems can be completely solved with the present invention which utilizes a unique foam plastic stiffener sheet and with processing steps which seal the edges of the foam structure to assure no grease penetration into the foam structure.  
         [0012]     The steps of manufacturing the foam sheet and package of the present invention include:  
         [0013]     1. A sheet structure is extruded with three layers. The outside layer is a white blend of polystyrene materials to provide a smooth printable surface. The inner layer is polystyrene foam to provide the preferred stiffness and economics. The bottom layer intended to contact the bacon is a blend of polystyrene and pigment to provide the desired color.  
         [0014]     2. The outside surface of the outside sheet is printed and a thin clear polypropylene sheet is either directly adhered to the printed surface or alternately is reversed printed and bonded to the solid polystyrene outside layer.  
         [0015]     3. The sheet structure, printed as set forth in step 2, is then run through a heat embossing step which collapses and seals the foam structure of the inner layer in areas of the sheet that will be die cut to form (a) windows for the bacon package and (b) edges defining the outer edges of the stiffener.  
         [0016]     4. After the embossing step, the stiffener is cut out of the extruded and printed sheet by cutting through the embossed areas to form the windows and outer edges. The cutting may be performed using a heated knife in order to assure that a seal is obtained along the cut edges so that no foam of the foam polystyrene layer is exposed at the seam in the event the heat embossing step does not totally collapse the foam to form a complete seal along the embossments. Other methods of forming a seal along the embossments may be used including laser, hot-air, plasma and induction heating or any other method of heat sealing.  
         [0017]     Since the structure is fully sealed in the cut areas, grease cannot soak in. Additionally, dust and fibers are not present as in the fiber board products of the prior art. No delaminating is experienced with the structure of the present invention.  
         [0018]     The embossing step can also be used to form a quilted or waffled surface which improves the stiffness and handling of the, foam stiffener and the finished bacon package.  
         [0019]     The embossing step can also provide decorative patterns in the printed surface such as a pig outline or other desired logo shapes. 
     
    
     IN THE DRAWINGS  
       [0020]      FIG. 1  is a flow diagram showing the manufacture of foam stiffener of the present invention.  
         [0021]      FIG. 2  is a perspective view of a section of tri-extruded foam/film as it is unrolled from a roll or web of such film.  
         [0022]      FIG. 3  is a perspective view showing the structure of  FIG. 2  following printing.  
         [0023]      FIG. 4  is a view similar to  FIG. 2  showing the application of polypropylene laminating film following printing as shown in  FIG. 3 .  
         [0024]      FIG. 5  is a perspective view showing the tri-extruded foam/film with reverse printed polypropylene film laminated thereto.  
         [0025]      FIG. 6  is a perspective view showing a pair of heated embossing rolls through which the web having the printed structure of  FIG. 4  is passed to form a plurality of stiffener sheets in the web of foam/film with polypropylene film laminate.  
         [0026]      FIG. 7  is a perspective view showing a plurality of stiffener sheets in the web after embossing and before being cut.  
         [0027]      FIG. 8  is a perspective view of the foam stiffener sheet following the cutting step.  
         [0028]      FIG. 9  is a schematic perspective view showing the embossed stiffener sheet being fed through a cutter.  
         [0029]      FIG. 10  is a perspective view of a complete foam stiffener sheet following cutting with an embossed logo thereon.  
         [0030]      FIG. 11  is a flow diagram showing the process of forming a bacon package utilizing the foam stiffener sheet of  FIG. 8 .  
         [0031]      FIG. 11A  is a view of the bacon pack as seen from the reverse side of  FIG. 11 .  
         [0032]      FIG. 12  is a sectional view taken through a heat embossed area.  
         [0033]      FIG. 13  is a sectional view taken through a heat embossed area following cutting to form windows.  
         [0034]      FIG. 14  is a perspective view showing an embodiment of stiffener sheet with ribs. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0035]     Referring to  FIGS. 1-10 , there is shown a roll  10  of tri-extruded foam/film being unrolled as an elongated web. The web of foam/film  12  has an outside layer  13  of solid polystyrene, preferably having a white pigment, which provides a smooth printable surface, an inner layer  14  of polystyrene foam and a bottom layer  15  of solid polystyrene intended to contact the bacon in the final bacon package. The bottom layer  15  is preferably pigmented a desired color, for example black or yellow. The overall structure of the tri-extruded foam/film has a thickness on the order of 0.015inch with the foam inner layer having a thickness on the order of 0.014 inch and each of the outside layer  13  and bottom layer  15  having a thickness on the order of 0.0005 inch.  
         [0036]     As shown in  FIG. 1 , as the web of tri-extruded foam/film  12  is unrolled from the supply roll  10 , it is passed through a printer  18  which prints a desired logo  19 , for example, the words “BACON SLICES 1 Pound” as shown in  FIG. 3 .  
         [0037]     Following printing, the tri-extruded foam/film  12  is passed through a laminator  20  which laminates a thin clear polypropylene sheet  22  over the outside layer  13  and the printed logo  19 . The polypropylene sheet  22  has a thickness on the order of 0.0005 inch and provides protection for the printed logo  19  which may readily be seen therethrough.  
         [0038]     If desired, in lieu of printing the outside layer  13 , the polypropylene sheet  22  could be reverse printed on the surface which contacts the. outside layer  13 . This may be seen in  FIG. 5  in which the logo “BACON PACK” was reverse printed on the polypropylene film  22  prior to being laminated to the outside layer  13 .  
         [0039]     The web having the printed and laminated structure of  FIG. 4  or  FIG. 5  is then passed through a heat embossing station  24  having a pair of heated embossing rolls  25  and  26  such as shown in  FIG. 6 . As may be seen in  FIG. 6 , the lower roll  26  has a smooth cylindrical surface  27  while the upper roll  25  has a plurality of raised areas  28  which will compress the tri-extruded foam/film  12  with the laminated polypropylene sheet  22  to form embossed areas  30  (see  FIG. 7 ) in which the foam is compressed to form, as a result of heat and pressure from the rolls  25  and  26 , solid or mostly solid polystyrene from what was previously the foam inner layer  14 . As a result, most or all portions of the embossed areas  30  are heat sealed. Additionally, the upper roll  25  has a raised area  31  defining a circumferential path  35 . (See  FIG. 7 ). The foam in this area is also compressed to form solid or mostly solid polystyrene.  
         [0040]     The upper roll also has a transverse raised area  41  following a straight line path. The transverse raised area  41 , upon embossing, forms a fold line  32  and does not necessarily form a heat seal.  
         [0041]     After passing through the heat embossing station  24 , the embossed web is moved through a cutting station  29  (See  FIG. 9 ) at which the web is then cut with a heated knife at a perimeter defined by the circumferential path  35  of  FIG. 7  and cut, also with a heated knife, through the embossed areas  30  to form windows  30 A, to form the final stiffener sheet  36  (see  FIG. 8 ) with sealed edges  33 , which stiffener sheet  36  may be then packaged for shipment to the company forming the bacon package. Cutting with heated knives assures that the perimeter edges  33  of the stiffener sheet  36  and all edges of the windows  30 A are completely sealed with solid polystyrene and that there is no exposed foam at such edges. Other methods of sealing the perimeter edges  33  and the edges of the windows  30 A may also be used including but not limited to laser sealing, hot-air heating, plasma heating and induction heating.  
         [0042]     As shown in  FIG. 9 , the cutting station  29  includes an upper cutting roller  50  having (i) raised cutting blades  51  to cut the sealed peripheral edge defining the circumferential path  35  and (ii) raised cutting blades  52  to cut the embossed areas  30  to form windows  30 A. The cutting station  29  also has a roller die anvil  54  with a smooth cylindrical surface  55  against which the cutting blades  51  and  52  cut the stiffener sheet  36  from the web. The cut stiffener sheets  36  are then delivered to a stacking station  42  for packaging and subsequent delivery to a bacon packer.  
         [0043]     As shown in  FIG. 10 , if desired an additional logo  38 , such as a pig, may be embossed in the stiffener sheet  36 . Additionally, as shown in  FIG. 14  additional stiffener ribs  40  may be embossed in the stiffener sheet  36 .  
         [0044]      FIG. 12  is a sectional view taken through one of the embossed areas  30  to show the compression and sealing of the foam to form solid or mostly solid polystyrene in the embossed area  30 .  FIG. 13  is a sectional view showing circumferential embossed areas  30  cut out to form a window  30 A.  
         [0045]     Referring to  FIG. 11 , there is shown schematically the process steps utilized by the bacon packer for using the stiffener sheet  36  to form the final bacon package. As shown in  FIG. 11 , the stiffener sheet  36  has four edges  33 A,  33 B,  33 C and  33 D, each of which was cut from an area along the circumferential path  35  which had been (1) heat compressed and sealed or (2) heat compressed and sealed by cutting with a heated knife or otherwise sealed so that the plastic at such edges is solid and no foam is exposed at such edges  33 A,  33 B,  33 C, and  33 D. Additionally, the embossed areas  30  are cut and sealed inside the embossing so that no foam is exposed at the edges of the windows  30 A. Also shown is the logo  19  (“BACON PACK”), the window areas  30 A, and fold line  32 . As shown in  FIG. 11 , step ( 1 ) the stiffener sheet  36  is folded along the fold line  32  with sliced bacon positioned therein step. Step ( 1 A) the stiffener sheet  36  folded over the bacon  40  may then be wrapped step ( 2 ),with film and vacuum packed step ( 3 ) to form the final bacon pack  44 .  FIG. 11A  shows the bacon pack  44  on the reverse side from that shown in the flow diagram of  FIG. 11 . It clearly shows the defining windows  30 A through which the bacon may be seen by the ultimate purchaser of the package.  
         [0046]     Under another embodiment of the present invention, it is contemplated that a stiffener sheet could be formed using a combined cutting and sealing technique to cut the outer periphery from the web such that the outer periphery is solid plastic throughout with no foam exposed at such outer periphery. Similarly the windows could be formed within the confines of such outer periphery by using a combined step of cutting and sealing along an annular path to define an inner periphery defining each window with such inner periphery being solid plastic throughout such that no foam is exposed at such inner periphery. Such cutting and sealing could be accomplished with heated knives, laser cutting and sealing, or any other process which effects a cutting and sealing to form edges having solid plastic throughout the thickness of such edges from the outside layer  13  of polystyrene to the inner layer  14  and through the bottom layer  15 .  
         [0047]     Many modifications will become readily apparent to those skilled in the art.