Patent Publication Number: US-6216855-B1

Title: Tray for containing foodstuffs and luxury foods which give off liquids

Description:
The invention relates to a tray for containing foodstuffs and luxury foods giving off liquids, particularly meat, fish or poultry, with a basic tray member having a base, side walls and transverse side walls, and which has at least two outer plies of waterproof plastic and an absorbent layer located between the plies, openings being provided in the upper ply facing the foodstuffs and luxury foods, for passage of the liquid into the absorbent layer. 
     Previous trays of the type named have an absorbent layer of paper, cellulose or the like. Re-use of such a tray, consisting for example of plastics, in the sense of a closed circuit, is difficult, as the layer (not consisting of plastic) must firstly be separated in a complex process. 
     On this basis it is the object of the present invention to provide a tray which may be simply re-used and nevertheless has a good capacity for absorbing liquid. 
     The purpose is achieved according to the invention in that the absorbent layer consists of an open-celled plastic preferably of an open-celled foam plastic. In contrast to other plies, this layer is not waterproof and thus absorbs the separated liquid into its open cells. Separation of the individual plies or of the layer in this construction is no longer necessary for re-use of old materials, as the outer plies and the absorbent layer consist entirely of plastic. 
     More advantageously, the lower ply consists of a closed-cell foam plastic, whilst the upper ply is produced from a compact, i.e. non-foamed plastic, particularly from a sheet. The closed-cell foam plastic is soft, pleasant to handle, has a high heat insulating effect and is waterproof. The upper compact ply has a relatively smooth surface and thus is pleasant in appearance. In the non-visible (lined) construction, the central absorbent layer is hidden from view, as are the liquids which have penetrated the absorbent layer, for example reddish meat juice. The upper compact ply can optionally be either coloured or uncoloured. Alternatively it may also be envisaged to associate with the outer side of the lower ply a further lowermost ply of compact plastics, particularly a sheet. The tray is then constructed in four plies or four layers. This additional lowermost ply can correspond to the upper ply, i.e. can be either coloured or uncoloured. 
     It is particularly advantageous if, in addition to the formation of the lower ply from closed-cell foam plastic, the (central) absorbent layer consists of open-cell foam plastic. The material involved here is totally open-celled, e.g. foam plastic. Correspondingly, the lower ply is formed from entirely closed-celled, e.g. foam plastic. In this way there is a separation of the tray which complies with requirements. This separation is also advantageous because the layer and the ply may be particularly easily formed either from entirely open-cell or closed-cell foam plastic. In this connection, entirely open-cell foam plastic or entirely closed-cell foam plastic means that, during manufacture of the corresponding layer or ply, an attempt is made to obtain either as many closed or as many open-cells as possible. In the ideal case all, i.e. 100% of the cells would either be open or closed. This ideal case however is not always achieved in practice, so that the absorbent layer, made of open-cell foam plastic, contains open cells to a small degree, and the lower ply made of closed-cell foam plastic, contains open cells to a small degree. As a rule, in the case of closed-cell foam plastics, at least 90% of the cells are closed, while with open-cell foam plastics at least 90% of the cells are open. Accordingly, when entirely closed cells are mentioned, this is to be taken to mean a foam plastic in which as many cells as possible are closed, but also a small proportion of the cells can be open. Conversely, in the case of an open-cell foam plastic, the majority of the cells are open, while a small proportion of the cells can be closed. 
     The invention further relates to a surrounding edge of the tray. The two plies are compressed together with the absorbent layer in the area of the surrounding edge, in such a way that the layer is no longer open-celled in this lateral area. For this purpose, the layer in the area of the surrounding edge of the tray is preferably partly compacted. The lateral area of the layer is rendered non-cellular by means of the compression procedure. Thus the absorbed liquid cannot pass out over the edge. In addition, the lateral compression is only carried out to such a degree that the lower ply in the lateral area does in fact lose strength, but remains flexible and thus is not compacted. 
     In this way sharp edges in the area of the surrounding rim are avoided. According to an advantageous further development of the invention, the base wall of the tray is at least partly curved in configuration. This curvature is of such type that at least the inner wall of the tray, upon which the articles to be contained by the tray rest, has a curvature. The curvature is such that the highest point is located roughly in the centre of the base wall. From this point the base wall drops away to the side walls or the transverse side walls. Thus the liquid accumulating in the interior of the tray can run off to the edges of the base wall or accumulate there. In this case the lateral areas of the base wall adjacent to the side walls and the lateral side walls must not be curved. Preferably, openings for removing the liquid to the absorbent layer are provided in the lateral areas of the base wall adjacent to the side walls and transverse walls, so that the liquids can also be removed at that point to which they have been passed due to the raised centre of the base wall. Further features of the invention will become apparent from the sub-claims. 
    
    
     Preferred embodiments of the invention, given by way of example will be explained in more detail in the following with reference to drawings, which show: 
     FIG.  1 : a plan view of a tray according to the invention, 
     FIG.  2 : a cross-section of the tray along line II—II in FIG. 1, 
     FIG.  3 : an enlarged cross-section similar to the cross-sectional view in FIG. 2, yet in the area of an opening for the passage of liquids, 
     FIG.  4 : an enlarged detail IV—IV from FIG. 2 in the area of a rim of the tray, 
     FIG.  5 : a plan view of a second embodiment of a tray according to the invention, 
     FIG.  6 : a cross-section of the tray along line V—V in FIG. 5, 
     FIG.  7 : an enlarged detail VI from FIG. 5 in the area of an opening in a base wall, 
     FIG.  8 : a cross-section through the opening in FIG. 7 along the line VII—VII. 
    
    
     The trays shown here are in three-layer form and are entirely made of plastic. 
     The tray  10  shown in FIGS. 1 to  4  has a lower ply  11  of liquid-type plastic, particularly of entirely closed-cell foam plastic, an upper ply  12  of liquid-type plastic particularly a compact, non-foamed plastic or made from a sheet, and an absorbent layer  13  located between the plies  11 ,  12 . The outer walls of the two outer plies  11 ,  12  form a so-called basic tray member. The plies  11 ,  12 , of equal size, and the layer  13 , of corresponding size, are connected together substantially over their entire surface. 
     The absorbent layer  13  in the present case likewise consists of plastic, i.e. of an open-cell plastic, preferably an entirely open-cell foam plastic. The layer  13  is thus suitable for absorbing or taking up liquids. 
     The upper ply  12  has a plurality of openings  14  at regular or irregular intervals. The openings  14  can extend entirely or partly through the layer  13 . FIG. 3 shows an alternative, i.e. openings  14  produced by stamping, forming an aperture tab  15 , which is pressed into the layer  13  and thus forms at that point a recess  16  as a continuation of opening  14 . The liquids given off by a piece of meat, fish or poultry in the tray can flow out through the openings  14  into the layer  13  and are absorbed or retained by the open cells of the layer  13 . 
     The basic tray body of the tray  10  has in a previously known way a flat base wall  22  and obliquely upwardly aligned side walls  17 ,  18  and corresponding transverse side walls  19 ,  20 . The side walls  17 ,  18  and transverse walls  19 ,  20  surround the base wall  22 . Connecting with the said side walls  17 ,  18  and transverse walls  19 ,  20  in an outward direction is a surrounding rim  21 . This is formed by compression of the two plies  11 ,  12  and of layer  13 . Thus the two plies  11 ,  12  and the layer  13 , of equal size, extend over the entire width and length of the tray  10 . 
     The individual plies  11 ,  12  and the layer  13  are compressed together in the surrounding rim  21  to such an extent that the absorbent layer  13  in this area has lost its absorbent, open-celled property (FIG.  4 ). In this area the layer  13  is waterproof, i.e. by means of entire or partial compacting. Accordingly, no liquid can emerge out of the surrounding rim  21 . In FIG. 4, the compacted region of the ply  12  and of the layer  13  has the width R. In this area R the layer  13  is compacted down to the thickness of the ply  12 . Both are thus of roughly the same thickness; i.e. they have a respective thickness of about 0.4 mm. Due to the compacting of the layer  13  in the region R of the surrounding rim  21 , this latter forms with the adjacent ply  12  a unified compacted plastic rim. 
     Finally, the surrounding rim  21  is so compressed that the lower play  11  is in fact reduced in thickness in this area, but remains flexible, being only partly compacted. In this area of reduced thickness (“R” in FIG. 4, the ply has a thickness of preferably only 1 to 2 mm. The surrounding rim  21  thus feels relatively soft, at least from below. There are no sharp edges. The described flexibility of the lower ply  11  and the compacting of layer  13  in the surrounding rim  21  may be achieved simultaneously, and do not exclude one another (FIG.  4 ). 
     In the region of the base wall  22  and in the region of the walls  17  to  20 , the ply  11  has the greatest thickness. The absorbent layer  13  is slightly thinner, while the upper ply  12 , due to its compact structure, is extremely thin both relative to the lower ply  11  and also to the layer  13 . The lower ply  11  and the layer  13  are produced from layers of identical density and/or thickness. During manufacture of the tray  10  in a deep-drawing process with preceding heating, the lower ply  11  expands, due to the closed cells, to a greater degree than the absorbent layer  13  with open cells. 
     Thus the thicker lower ply  11  results relative to the layer  13 . 
     As FIG. 1 shows, the openings  14  are provided only in the opening of the base wall  22 . Corresponding openings  14  may however also be provided in the region of the side wall  17 ,  18  and/or of the transverse side walls  19 ,  20 . 
     FIGS. 5 to  8  show a tray  23  according to a second embodiment of the invention. The tray  23  is also in a three-layer form. The tray  23 , like tray  10 , has a lower ply  24  of waterproof plastic, particularly of entirely closed-cell foam plastic, an upper ply  25  of waterproof plastic, particularly of a compact non-foamed plastic, for example a sheet, and an absorbent layer  26  located between the plies  24  and  25 . The absorbent layer  26  also consists of a plastic, i.e. of an open-cell plastic, preferably an entirely open-celled foam plastic. 
     The tray  23  has a basic tray body which corresponds in form to the basic tray body of the tray  10  of FIGS. 2 to  4 . In this respect reference is made to the description of tray  10 , identical reference numbers identifying identical parts. 
     In tray  23  also, the plies  24  and  25 , and the layer  26 , with respect to their surface areas, are of equal size. The conditions of thickness of plies  24 ,  25  and of the layer  26  roughly correspond to those of the tray  10  in FIGS. 1 to  4 . Also, the surrounding rim  21  of the tray  23  is waterproof, the liquid-absorbing layer  26  in the area of the surrounding rim  21  being at least compressed in such a way that its cells are closed and thus no liquids can flow outwards over the rim  21 . The plies  24  and  25  are substantially connected over their entire surface with the intermediate layer  26 , as is the case with the tray  10  in FIGS. 1 to  4 . 
     In contrast to tray  10 , in the tray  23  the base wall  27  is slightly curved. This curvature is such that the highest point is located roughly in the centre of the base wall  27  and from this point extends downwards both the side walls  17  and  18  and to the transverse side walls  19 ,  20 . This inclination of the base wall  27  aligned towards the edges of the tray  23  terminates shortly before the side walls  17  and  18  and the transverse side walls  19  and  20 , so that lateral areas of the base wall  27  extend roughly horizontally. 
     The curvature in the base wall  27  is formed by an absorbent layer  26  which is slightly curved only on the upper side. The underside of the curved layer  26  is flat (FIG.  5 ). The volume of this absorbent layer  26  is in this way increased. Despite the curvature of the base wall  27 , the plies  24  and  25  have parallel outer walls, so that the underside of the base wall  27  of tray  23 , delimited by the lower wall of the lower ply  24 , is flat. The thin upper ply  25  is adapted, in the curved area of the base wall  27 , to the curved configuration of the absorbent layer  26  only at the upper side of the same, so that the upper ply  25  has a curved configuration at points, and thus the base wall  27  is curved at least in the central area on the inner side of the tray  23 . 
     It will be seen from FIG. 5 that the base wall  27  has openings  28  only on a partial area of its surface. These openings are located in lateral areas of the base wall  27  adjacent to the side walls  17  and  18  and the transverse side walls  19  and  20 , i.e. preferably on such lateral areas of the base wall  27  which are not curved. In this way the openings  28  surround the curved area of the base wall  27 . Accumulating liquid in the interior of the tray  23  can flow from the central highest point of the base wall  27  to the edges of the base wall  27  and the openings  28  located at that point. 
     In the case of the tray  23 , the openings  28  are formed in a special way, i.e. by a cruciform incision. This cruciform incision extends substantially through the upper, sheet-like ply  25 . Thus in the area of each opening  28 , the play  25  receives four triangular tabs  29 , which are pressed into the central absorbent layer  26 . In this way there are provided, between edges  30  of adjacent tabs  29 , intermediate spaces  31 , at which the waterproof upper ply  25  does not overlap the absorbent central layer  26 , so that liquids can pass through the intermediate spaces  31  to the absorbent layer  26  (FIGS.  7  and  8 ). By means of pressing the tabs  29  into the layer  26 , there results in the area of each opening  28  a recess aligned towards the centre of the same in the base wall  27 , so that the flow of liquids to each opening  28  is simplified and intensified. 
     It may also be envisaged to provide the tray  23  with openings  28  formed or manufactured in another way, and also to undertake the distribution of the openings on the base wall  27  and if necessary also the transverse side walls  19 ,  20  and/or side walls  17 ,  18  in a way different from that shown in FIG.  5 . 
     Finally it may be envisaged to form the trays  10  and  23  from more than the two plies  11 ,  12 ;  24 ,  25  and the intermediate absorbent layer  13 ;  26  as shown in FIGS. 1 to  8 . For example there may be provided beneath the outer side of the lower ply  11 ;  24  an additional (lowermost) ply, which covers the entire outer side of the lower ply  11 ;  24 . This lowermost ply preferably consists of compact ply, for example a thin sheet similar to the upper ply  12 ;  25 . The lowermost ply may also be coloured or carry a colour pattern or a printed message.