Abstract:
Disposable polymeric container covers, methods of manufacturing the same, and machines for manufacturing the same are disclosed wherein the cover may include a polymer film adapted to enclose a bowl or the like, and an elastic film proximate thereto adapted to seal the cover against the bowl. The elastic film may be provided as an annular member completely surrounding the bowl, or in segments around an otherwise non-elastic ring. The method may include co-extruding the elastic with the non-elastic polymer, or stamping the elastic and non-elastic polymers as separate pieces and then heat sealing them together.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application is related to, and claims the priority benefit of, U.S. Provisional Patent Application No. 60/478,479, filed Jun. 13, 2003. 
     
    
     
       FIELD OF THE DISCLOSURE  
         [0002]    The disclosure generally relates to polymeric container covers, methods of manufacturing the same, and machines for manufacturing the same.  
         BACKGROUND OF THE DISCLOSURE  
         [0003]    Disposable container covers capable of covering containers of various sizes and shapes have been in use for many years. Such covers typically include a plastic film, such as polyethylene, provided in sufficient dimension to overlay the container opening. The film then employs surface tension or elastic bands to secure the film to the container, such as with Saran® wrap or Quick Covers®, respectively, both being products of the present assignee, with the latter having an elastic band sewn directly to the film around its perimeter. The elastic band bordering the film is attached in such a manner that tension is created on the film, thereby creating a hollow enclosure with an expandable opening for placing atop and around containers of various sizes and shapes.  
           [0004]    Use of such container covers is common for both perishable and nonperishable items. While these covers are beneficial in many respects, they are not without room for improvement. A common problem with existing container covers is the lack of an effective seal between the cover and the container. This is especially problematic with regard to food storage. First, depending on the size of the container cover relative to the container, the conventional container covers described above are vulnerable to slippage and inadvertent removal from the container. Any attempt at preserving freshness or protecting the contents of the container from exposure to various elements is futile where the container cover does not actually cover the container, but instead, slips off the container.  
           [0005]    Even when such conventional covers remain appropriately positioned on a container, their sealing capabilities are limited. More specifically, given the limited constriction afforded by elastic bands, the susceptibility of films to lose surface tension, and/or the irregular shapes of the containers being sealed, air and moisture can flow relatively freely in and out of containers covered with conventional container covers. Consequently, where a substantial or hermetic seal is desired, as opposed to where air or moisture ventilation is desired, the goal of preserving the freshness of perishable items is less likely to be realized with conventional disposable covers.  
           [0006]    An additional problem with conventional container covers relates to manufacturing. Specifically, conventional container covers, as described above, require the slow, labor intensive manufacturing step of manually sewing an elastic band to the periphery of the film. These covers do not readily lend themselves to high-speed automated manufacturing, in turn, driving up the cost and time of manufacturing conventional container covers. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 a  is a plan view of a container cover according to the teachings of the disclosure.  
         [0008]    [0008]FIG. 1 b  is a cross-sectional view taken along line  1   b - 1   b  of the container cover shown in FIG. 1 a.    
         [0009]    [0009]FIG. 2 a  is a plan view of an apparatus for manufacturing container covers during a preliminary stage according to the teachings of the disclosure.  
         [0010]    [0010]FIG. 2 b  is a plan view of preliminary output atop a receiving device according to the teachings of the disclosure.  
         [0011]    [0011]FIG. 3 a  is a plan view of an apparatus for manufacturing container covers during a standard stage according to the teachings of the disclosure.  
         [0012]    [0012]FIG. 3 b  is a plan view of standard output atop a receiving device according to the teachings of the disclosure.  
         [0013]    [0013]FIG. 4 is a perspective view of a first phase of a standard stage of operation of an apparatus for manufacturing container covers according to the teachings of the disclosure.  
         [0014]    [0014]FIG. 5 is a perspective view of a second phase of a standard stage of operation of an apparatus for manufacturing container covers according to the teachings of the disclosure.  
         [0015]    [0015]FIG. 6 is a perspective view of a third phase of a standard stage of operation of an apparatus for manufacturing container covers according to the teachings of the disclosure.  
         [0016]    [0016]FIG. 7 is a perspective view of a fourth phase of a standard stage of operation of an apparatus for manufacturing container covers according to the teachings of the disclosure.  
         [0017]    [0017]FIG. 8 a  is a plan view of a container cover according to the teachings of the disclosure.  
         [0018]    [0018]FIG. 8 b  is a plan view of a container cover according to the teachings of the disclosure.  
         [0019]    [0019]FIG. 9 is a perspective view of an apparatus for manufacturing container covers according to the teachings of the disclosure.  
         [0020]    [0020]FIG. 10 a  is a plan view of a first stage of production of a container cover according to the teachings of the disclosure.  
         [0021]    [0021]FIG. 10 b  is a plan view of a second stage of production of a container cover according to the teachings of the disclosure.  
         [0022]    [0022]FIG. 10 c  is a plan view of a third stage of production of a container cover according to the teachings of the disclosure.  
         [0023]    [0023]FIG. 10 d  is a plan view of a fourth stage of production of a container cover according to the teachings of the disclosure.  
         [0024]    [0024]FIG. 10 e  is a plan view of a fifth stage of production of a container cover according to the teachings of the disclosure.  
         [0025]    [0025]FIG. 10 f  is a cross-sectional view of the first stage of production of a container cover as shown in FIG. 10 a.   
     
    
       [0026]    While the disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the disclosure to the specific embodiments disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the disclosure as defined by the appended claims.  
       DETAILED DESCRIPTION  
       [0027]    Referring now to the drawings and with specific reference to FIGS. 1 a  and  1   b,  a container cover  10  is provided comprising a first polymer  12  and a second polymer  14 . A first layer  16  comprises the first polymer  12  and a second layer  18  comprises the second polymer  14 , said layers operatively associated with one another at a first surface  11  of the second layer  18 . In some embodiments, there may be additional layers, such as an insulating layer operatively associated with the second layer  18  at a second surface  13  of the second layer  18 . Such a configuration is useful as it helps prevent the contamination of the insulating layer. The first and second layers  16 ,  18  are sealed about a perimeter  17 . Although the container cover  10  is shown in a circular shape, that is for illustrative purposes only, as the container cover  10  may be made in any shape or size. The shape and size may be customized to fit a particular container. Custom fitting can help prevent or eliminate excessive plastic folds or gather in the container cover.  
         [0028]    The first polymer  12  may comprise an elastomeric material, e.g. an elastic film. Compatible elastomeric materials include, but are not limited to, Tredegar Product CEX-816WR, Tredegar Product X-25132, Dow Chemical Product Affinity—Polyolefin Plastomers 8200 Series, Dow Chemical Product Affinity—Polyolefin Plastomers PF 1140 Series, Dow Chemical Product Affinity—Flexomer 9078 Series. The second polymer may comprise, but is not limited to, polyethylene (PE) or polypropylene (PP). An additional insulating layer may comprise, but is not limited to, 3M Thinsulate® or non-woven PE.  
         [0029]    The container cover  10  may also comprise a handle that allows for lifting and/or “burping” of the container. That is, pulling such a handle allows for air to be released from the container. Such a handle may be located, for example, at a center  15  on the second surface  13 , so as to be operatively associated with the cover  10 . In some embodiments, the cover  10  will have one or more handles operatively associated along the perimeter  17 .  
         [0030]    A method of manufacturing a container cover  10  using an apparatus (machine)  20  is presented in FIGS. 2 a  and  2   b . A first web  22  comprises the first polymer  12 , and a second web  24  comprises the second polymer  14 . The first web  22  may be positioned above the second web  24 . Although the positioning of said webs is shown as transverse and perpendicular in FIGS. 2 a  and  3   a , the webs may take on a range of relative positions, and in some embodiments may be parallel. The first web  22  may be spooled from a first supply roll  26  to a first receiving roll  27 . The second web  24  may be spooled from a second supply roll  28  to a second receiving roll  29 . The first web  22  may be advanced towards the first receiving roll  27 , and the second web  24  may be advanced towards the second receiving roll  29 . The first and second webs  22 ,  24  are superimposed at position  52 . A receiving device  25  may be placed beneath the second web  24  at position  52  to receive container covers, e.g.  10 , after they have been sealed and cut from the first and second webs  22 ,  24 . In some embodiments, the receiving device  25  comprises a vacuum arm that may receive container covers, from which they are delivered for packaging.  
         [0031]    [0031]FIG. 2 a  illustrates by use of references numbers  32 ,  34 ,  36 ,  38 ,  40 ,  50 ,  52 ,  54  and  56  positions in a plane of the apparatus  20 . Said positions help describe the positions that the first and second webs  22 ,  24  and components thereof may occupy.  
         [0032]    [0032]FIG. 2 a  illustrates a preliminary stage  21  of the manufacturing process, which generates preliminary output  60  shown in FIG. 2 b . The preliminary stage does not generate the container cover  10 , but rather the scrap covers  62 ,  64  and  66  of the preliminary output  60 , which may be recycled. In the preliminary stage  21 , a first pilot hole  130  is at position  30 . Such pilot holes may be punched out at this position or formed at an earlier stage. The apparatus  20  at position  32  generates a small hole in the first web, e.g.  132 , a small hole in the second web  42 , and a scrap small cover, e.g.  62 . The apparatus  20  at position  34  generates a medium hole in the first web, e.g.  134 , a medium hole in the second web, e.g.  44 , and a medium scrap cover, e.g.  64 . The apparatus at position  36  generates a large hole in the first web, e.g.  136 , a large hole in the second web, e.g.  46 , and a large scrap cover, e.g.  66 .  
         [0033]    [0033]FIGS. 3 a  and  3   b  represent a standard stage  31  of the apparatus  20 , which generates a container cover, e.g.  10 , in three different sizes as illustrated by the covers  72 ,  74  and  76  of the standard output  70 . In FIG. 3 a , the first web  22  and the second web  24  have each advanced one position. A second pilot hole  230  is now in position  30 . The first pilot hole  130  occupies position  32 , the small hole  132  occupies position  34 , the medium hole  134  occupies position  36 , and the large hole  136  occupies position  38 . The small hole  42 , medium hole  44  and large hole  46  of the second web  22  occupy position  54 . The apparatus  20  at position  32  generates a small hole in the first web, e.g.  232 , a small hole in the second web  142 , and a small cover, e.g.  72 . The apparatus  20  at position  34  generates a medium hole in the first web, e.g.  234 , a small hole in the second web, e.g.  144 , and a medium cover, e.g.  74 . The apparatus at position  36  generates a large hole in the first web, e.g.  236 , a large hole in the second web, e.g.  146 , and a large cover, e.g.  76 .  
         [0034]    [0034]FIGS. 4-7 illustrate four phases,  33 ,  35 ,  37  and  39  respectively, of the standard stage  31  of the manufacturing process. In FIG. 4, the first web  22  and second web  24  have advanced from their respective positions they had occupied in the preliminary stage  21 , but the container covers  72 ,  74  and  76  have not yet been produced. An output generator  80  may comprise three stamping modules: a large generator module  81 , a medium generator module  88  and a small generator module  95 . While three generator modules are illustrated, there is no limit to the number of modules in a given stamping apparatus  80 . Each generator module, e.g.  81 ,  88  and  95 , may comprise a sealing device, e.g.  82 ,  89  and  96 , and a stamping device, e.g.  85 ,  92  and  99 . Each sealing device may comprise a sealing shaft, e.g.  83 ,  90  and  97 , and a sealing head, e.g.  84 ,  91  and  98 . Each stamping device may comprise a stamping shaft, e.g.  86 ,  93  and  100 , and a stamping head, e.g.  87 ,  94  and  101 . Each sealing device may be housed within the respective stamping device. The output generator  80 , modules  81 ,  88  and  95 , sealing devices  82 ,  89  and  96 , stamping devices  85 ,  92  and  99 , and other components of the output generator  80  may all take on a number of different forms, positions, shapes, sizes, etc., and those shown are for illustrative purposes only. In the first phase  33 , both the sealing devices and the stamping devices are in their retracted positions.  
         [0035]    [0035]FIG. 5 illustrates a second phase  35  of the standard stage  31 , in which the three sealing devices  82 ,  89  and  96  have dropped and made contact with the first web  22 , which in turn is in contact with the second web  24 . The stamping devices  85 ,  92  and  99  remain in the retracted position. The sealing devices serve to seal the first and second webs  22 ,  24  together at respective positions  32 ,  34  and  36 . This sealing may be accomplished by any number of processes. In one embodiment the webs are sealed together using heat. The sealing devices are in contact with the first and/or second web for a sufficient dwell time to allow the webs to fuse.  
         [0036]    [0036]FIG. 6 illustrates a third phase  37  of the standard stage  31 , in which both the sealing devices  82 ,  89 , and  96 , and the stamping devices  85 ,  92  and  99  have dropped and have become associated with the first and second webs  22 ,  24 . The stamping devices serve to cut out the container covers  72 ,  74  and  76  from their respective positions  32 ,  34  and  36 . The container covers may be cut out by any number of processes including hot wire, hot knife, razor blades, laser, ultrasound, molten plastic, etc.  
         [0037]    [0037]FIG. 7 illustrates a fourth phase  39  of the standard stage  31 . Both the sealing devices  82 ,  89 , and  96 , and the stamping devices  85 ,  92  and  99  have again retracted. The container covers  72 ,  74  and  76  have been received by the receiving device  25 . The fourth phase  39  of the standard stage  31  illustrated in FIG. 7 corresponds to the planar views shown in FIGS. 3 a  and  3   b . Following the fourth phase  39  shown in FIG. 7, the first web  22  and the second web  24  may both move one position to arrive at a relative position in respect to position  52  so that the first phase  33  of the standard stage  31  repeated and the cycled started again.  
         [0038]    While the modules have been described as acting in unison that is for illustrative purposes only. In some embodiments the modules may operate independently of one another. In some embodiments, fewer than all of the modules may be used. In some embodiments the first and second webs  22 ,  24  are the product of multiple sublayers. For example the second web may comprise both a PE layer and an insulating layer. Layers or sublayers may be quilted together, or attached in other ways. In some embodiments an insulating layer is attached to the second web  24  prior to attachment of the first web  22 .  
         [0039]    In some embodiments, the first and second webs  22 ,  24  are of different widths as those shown in figures. In some embodiment the second web  24  is not a single sheet but rather made of three, or a different number, separate sheets moving parallel to one another. In some such embodiments the sheets may move at different speeds relative to each other. The webs  22 ,  24  may have any number of thicknesses. In some embodiments, the thickness of each web is between 1 and 3 mm.  
         [0040]    [0040]FIG. 8 a  shows another container cover  110  that can be manufactured according to the methods of the disclosure. The cover  110  is composed of first and second polymers  12 ,  14 , and first and second layers  116 ,  118 . The first and second polymers,  12 ,  14 , may comprise those materials, and others, described above in respect to cover  10 , e.g. polymer  12  may comprise an elastic material, e.g. an elastic film. The first layer  116  comprises four regions. A first region  151  and second region  153  may comprise the first polymer  12 , whereas the third region  161  and the fourth region  163  may comprise the second polymer  14 . The first and second regions  151 ,  153  may be diametrically opposed to each other, and the third region  161  and fourth region  163  may be diametrically opposed to each other. The second layer  118  may comprise the second polymer  14 . The first layer  116  is operatively associated with the second layer  118 , said layers being sealed about a perimeter  117 .  
         [0041]    [0041]FIG. 8 b  shows yet another container cover  210  that can be manufactured according to the methods of the disclosure, and which is a variation on the cover  110 . The cover  210  is composed of first and second polymers  12 ,  14 , and first and second layers  216 ,  218 . The first layer  216  comprises eight regions. A first region  151 , second region  153 , third region  155  and fourth region  157  may comprise the first polymer  12 , whereas the fifth region  165 , sixth region  167 , seventh region  169  and the eighth region  171  may comprise the second polymer  14 . The first region  151  and second region  153  may be diametrically opposed, as may the third region  155  and fourth region  157 . The second layer  218  may comprise the second polymer  14 . The fifth region  165  and sixth region  167  may be diametrically opposed to one another, as may the seventh region  169  and eighth region  171 . The first layer  216  is operatively associated with the second layer  218 , said layers being sealed about a perimeter  217 . As discussed in relation to cover  10 , the covers  110  and  210  may be produced in any shape or size, and those depicted in the figures are for illustrative purpose only.  
         [0042]    The apparatus  320 , shown in FIG. 9, may be used to manufacture the container covers, e.g.  10 ,  110 ,  210  and other container covers. As depicted, the apparatus  320  is set up to manufacture the lid  110 . The apparatus  320  comprises a first extruder  341  that may extrude a first polymer  12  and a second extruder  343  that may extrude a second polymer  14 . The extruders  341  and  343  are operatively associated so that they may coextrude a multipolymer web  370  that may comprise both a first polymer  12  and second polymer  14 . There is no limit to the number of polymers that may be comprised by the multipolymer web  370 . The apparatus  320  also comprises a stamping device  347 , a folding device  349  (e.g. a folding board), a sealing device  350 , a cutting device  354 , a conveying device  359 , a reclamation system  361 , and a stacking device  363 . The sealing device may comprise a first heat sealer roll  351  and a second heat sealer roll  353 . The cutting device may comprise a first die cutter roll  355  and a second die cutter roll  359 . The stacking device  363  may comprise a stacking tray.  
         [0043]    [0043]FIGS. 10 a - 10   e  show stages,  371 ,  373 ,  375 ,  377  and  379 , of processing of the web  370  as it moves through the apparatus  320  as indicated in FIG. 9. As shown in FIG. 10 a,  in a first stage  371 , the web  370  has just emerged from the extruders  341 ,  343 . The web comprises a first portion  381  and a second portion  383 . The first portion  381  comprises both first polymer  12  and second polymer  14 . The first portion  381  comprises a stripe  389  flanked by two flanking regions  385 ,  387 . The stripe  389  may comprise the first polymer  12 , and the flanking regions  385 ,  387  may comprise the second polymer. The second portion  383  may comprise the second polymer  14 . Additional features of the web  370  are illustrated in FIG. 10 e,  which shows a cross-sectional view of the web  370  depicted in FIG. 10 a.  The first portion  381  has a first surface  391  and a second surface  393 . The second portion has a first surface  395  and a second surface  397 . The first portion  381  may be substantially equal is size to the second portion  383 .  
         [0044]    [0044]FIG. 10 b  illustrates the second stage  373 . The stamping device  347  has already cut out a first hole  441 , and the stamping device  347  is shown in the process of stamping out a second hole  443 . The holes, e.g.  441 ,  443 , may be stamped out so that the stamp is centered on the stripe  389  and overlaps with the flanking regions  385 ,  387  as illustrated. However, this is for illustrative purposes only. For example, the stamping device  347  can be sized and/or the stripe  389  sized so that the hole  441  does not overlap the flanking regions  385 ,  387 , but is rather contained by the stripe  389 . Such an arrangement allows for the production of the container cover  10  shown in FIGS. 1 a  and  1   b.  In FIG. 10 b,  the first hole  441 , having already been formed, is shown distal from the extruders  341 ,  343 , relative to the second hole  443 .  
         [0045]    [0045]FIG. 10 c  shows the web  370  during a third stage  375 , after it has been folded by the folding device  349 . During folding, the first portion  381  and second portion  383  may be folded together so that the first surface  391  of the first portion  381  may be brought closer and/or in contact with the first surface  395  of the second portion  383 . In the alternative, the second surface  393  of the first portion  381  may be brought closer and/or in contact with the second surface  397  of the second portion  383 .  
         [0046]    [0046]FIG. 10 d  shows the web  370  as it travels through a fourth stage  377 . The first and second portions  381 ,  383  have already been sealed about a perimeter  445  surrounding the first hole  441 . The first and second portions are shown in the process of being sealed together by the sealing device  350  about a perimeter  447  surrounding the second hole  443 . While the holes  441 ,  443  are shown facing toward the first roller  351  and away from the second roller  353  that is for illustrative purposes only. The opposite orientation is also possible depending on how the web  370  is positioned in the apparatus  320 , and how the web  370  is folded.  
         [0047]    [0047]FIG. 10 e  shows a fifth stage  379 . The cutting device  354  cuts the web  370  about a perimeter  451  surrounding the perimeter  447  and the second hole  443 . The web  370  has already been cut about a perimeter  449  surrounding the perimeter  445  and the first hole  441  to form the container cover  110 . The cover  110  rides on a conveying device  359  that will take it to a stacking device  363  that will ready the cover  110  for packaging. As described in respect to FIG. 10 d,  the orientation of the web  370 , as well as the container cover  110 , are for illustrative purposes only, and the opposite orientation is also possible. The now spent web  372 , the residual product of the web  370 , can be seen in FIG. 9. The spent web may be taken to a reclamation device  361 , recycled and reused.  
         [0048]    Container covers  10 ,  110 ,  210  and others may be alternatively assembled using a turntable. The first layers, e.g.  116 ,  216 , are assembled from components corresponding to the regions, e.g.  151 ,  153 ,  161 ,  163  in the case of cover  110 , and  151 ,  153 ,  155 ,  157 ,  165 ,  167 ,  169 , and  171 . The regions are sealed together. The assembled first layer, e.g.  16 ,  116 ,  116  is then attached to the second layer, e.g.  18 ,  118 ,  218  about a perimeter, e.g.  17   117 ,  217 . In some embodiment the second layer, e.g.  18 ,  118 ,  218 , rests on the turntable and the regions are attached the second layer directly.  
         [0049]    The foregoing description of container covers, methods of manufacturing container covers and machines for manufacturing container covers have been set forth merely to illustrate the disclosure and are not intended to be limiting. Because modifications of the disclosed embodiments incorporating the spirit and substance of the disclosure may occur to persons skilled in the art, the disclosure should be construed to include everything within the scope of the claims to be presented and equivalents thereof.