Abstract:
A container having an expandable thickness for better insulation. The container has two walls which may be expanded to form an insulating air space therebetween. The expansion may be caused by compressible foam, an expandable strip material, a projection running on an inclined surface arrangement or by a gas generating material. The expansion may be activated by removing a vacuum, pulling a physical strip, by rotating one layer within the other or by crushing microcapsules to release gas. The expanded container provides better insulation for hot foods but allows a smaller thickness for storage.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates generally to a container for hot food products and more particularly to a container having an expandable space between two layers to provide a thermally insulating space to prevent hot food from cooling.  
         [0003]     2. Description of the Background  
         [0004]     Due to the pace of modern life, it has become very common for many people to rely on carry-out food services for the preparation of many of their meals. This presents a special problem for the food providers since food which is prepared and sold at a certain temperature may be very delectable, but is less tasty if the food is allowed to cool before eating. While this may be a problem of a lesser degree if the food is being eaten on the spot, it is a real difficulty for take-out services. Over the years, a number of different types of containers have been developed, especially of the paper product variety and especially with various coatings to prevent the moisture from the food from softening the paper. Other products have also been used, such as styrofoam which provides insulation in the thickness of the container wall.  
         [0005]     No matter what the actual material, the user of a container is faced with a two pronged problem. On the one hand, a thicker walled container typically provides better insulation and allows the customer to keep his food hot longer, thus providing a better experience for the customer. On the other hand, thicker walled material require additional storage space and often additional cost. Thus, it is difficult to have a container which is thin for storage and transportation but which provides superior insulation ability in use.  
       SUMMARY OF THE INVENTION  
       [0006]     Accordingly, the present invention is an improvement over previous arrangements by providing a container which is thin for storage, but which can be dynamically expanded at the time of the use.  
         [0007]     The present invention further provides a two walled container which has walls close to each other for storage and which are expanded in use to provide extra insulation.  
         [0008]     The present invention also provides a two walled container which is expanded before using.  
         [0009]     The present invention still further provides a multi-walled container which is expanded during use to provide for extra space between the walls.  
         [0010]     The present invention provides a double walled container having compressed foam inserts under pressure between the walls which are expanded upon use to provide an air space between the walls.  
         [0011]     The present invention also provides a double walled container having a flat insert between the layers, which when activated forms an expanded shape to separate the walls and provide extra insulation.  
         [0012]     The present invention further provides a double walled container having corresponding shapes which when rotated causes the shapes to separate and provide space between the walls.  
         [0013]     The present invention further provides a container having double walls with a material placed therebetween to generate gas when activated.  
         [0014]     The present invention also provides a method for expanding a container.  
         [0015]     Briefly, the invention achieves this by providing a container in the form of a bowl or bag which has two layers with a mechanism therebetween which can be released by a physical action such as pulling a string, by releasing a vacuum seal or by crushing microcapsules or a matrix material or allowing reactants in separated chambers to come together, to generate gas so as to force the two layers apart and leave an air space between the layers which acts as insulation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:  
         [0017]      FIGS. 1A and 1B  show a first embodiment of the present invention.  
         [0018]      FIGS. 2A and 2B  show an enlarged detail of one portion of  FIG. 1 .  
         [0019]      FIGS. 3A and 3B  show a second embodiment of the present invention.  
         [0020]      FIGS. 4A-4C  show a third embodiment of the present invention.  
         [0021]      FIGS. 5A and 5B  show a fourth embodiment of the present invention.  
         [0022]      FIG. 6  shows a variation of the second embodiment of the present invention.  
         [0023]      FIGS. 7 and 8  show two variations of a fifth embodiment of the present invention.  
         [0024]      FIGS. 9-11  show three variations of a sixth embodiment of the present inventions.  
         [0025]      FIGS. 12A and 12B  show a variant of the sixth embodiment of the present invention.  
         [0026]      FIGS. 13A and 13B  show a second variant on the sixth embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]     Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.  
         [0028]     Referring now to  FIG. 1A , a first embodiment of the invention is shown as container  10  in the shape of a bowl. The container includes an outer layer  12  and an inner layer  14 . This Figure shows a container in the compressed or storage state.  FIG. 1B  shows the container after it has been expanded to the state in which is used. The two layers meet at their outer edges to form a pair of lips  18  and  19  which are connected. A layer of foam material  16  is placed between the two layers. While the Figures shows this foamed material in separate pieces, it is possible that it may be in the shape of a solid sheet, a matrix, web, or any other shape. Also, although the foam is shown only on the bottom of the bowl, it also could extend up the sides.  
         [0029]     The foam is compressed in the storage state and allowed to expand in the expanded state as shown in  FIG. 1B . The expansion may occur in a number of different manners. It is possible that the foam is physically compressed and held in place by a band or tape which may then be removed when the container is about to be used, in order to allow the foam to expand. It is also possible to replace the air between the walls with a vacuum seal which will then be released by puncturing the seal and allowing air to enter.  
         [0030]     The particular manner of compression is not as important as the fact that the two layers may be expanded to allow an air space to be formed between layers  12  and  14 . This dead air space acts as a marvelous insulator and retains generally more heat than traditional single walled containers. The lips  18  and  19  are originally formed as shown in  FIG. 2A  and are allowed to expand as shown in FIG.  2 B while remaining in contact. Such an arrangement is necessary due to the separation of the two layers.  
         [0031]     Although the present invention has been described in terms of a bowl shape, similar arrangements can be made in the form of a plate, or even in the form of a bag for carrying the food home. Lids having this arrangement could also be supplied. Also, although the discussion centers on keeping foods hot, it is equally applicable for cold foods which must remain cold. Of course, the containers can be used for materials other than food which require heat retention.  
         [0032]     The second embodiment of the invention is shown in  FIGS. 3A and 3B . In this arrangement, container  20  is formed by a two wall structure including an outer wall  22  and an inner wall  24 , in a fashion similar to that of the first embodiment. However, in place of compressed foam, the bottom contains an expandable flat mesh  26 . This mesh may be for example, a sheet of material having slits formed therein. When the material is pulled from one side, the slits cause the material to turn slightly sideways and to expand the areas between slits so as to form an expanded material. If the space between slits is of the appropriate size, the distance between the two layers increases and is supported by the expanded material.  
         [0033]     In  FIG. 3B , the expanded material  26  forms zig-zag shapes which supports the two layers with a space therebetween. The result is an increased distance between the layers and an air space which acts as an insulator.  
         [0034]     In order to actuate the expandable material, a strap  28  is attached to one end thereof. The employees prepares the container for use by pulling on the strap, which causes the expandable material to stretch and form the extended arrangement causing the two walls to separate. The actual shape of strap  28  is unimportant and can be a loop, a handle or a tape and may be of any material which is strong enough to withstand the pulling necessary to expand the material.  FIG. 6  shows such a two strap arrangement with the two straps being joined by velcro and holding the lid and container together.  
         [0035]     The strap can serve a second purpose of bundling the two walls of the container, or in configurations of a container and matching lid, the strap can serve to tie the lid and container together in storage. The strap can loop around the container and lid elastically or can be a two strap arrangement tied together by any convenient fastening means including clips, velcro, buttons, spring biased fasteners and the like.  
         [0036]     A third embodiment is shown in  FIGS. 4A  to  4 C. In this arrangement, container  30  includes an outer layer  32  and an inner layer  34 . These layers are similar to the two previous arrangements, except that the bottoms of the two layers are different. That is, the bottom of the inner layer has short legs or projections  36  which are arranged at equal distances around the bottom. The outer layer contains 3 recesses  38  which have sloped inner walls. As shown better in  FIG. 4B , in the stored or compressed state, projection  36  extends downwardly into the deepest part of recess  38  so that the two layers are close to each other. When an expansion is desired, the employee rotates the inner layer relative to the outer layer. The result is that the projection  30  rides along the inclined bottom of the recess  38  until it reaches the shallow end. As a result, the projection is lifted upwardly along with the inner layer  34 . The result is that the two layers are separated and an air space is formed therebetween.  
         [0037]     The recesses  38  are placed equally around the bottom of the outer layer  32 . The extent of each recess must be short enough that the recesses do not contact each other. However, the recesses must be otherwise long enough so that the incline in the recess is gentle enough for the projection to move easily. Although the example shows 3 projections on 3 recesses, any number can be utilized as long as the number of projections and recesses are similar.  
         [0038]     A fourth embodiment is shown in  FIGS. 5A and 5B . In this arrangement, a container  40  includes an outer layer  42  and an inner layer  44 . The space between the layers includes a material which is capable of generating gas when activated. Thus, the material may include microcapsules which have citric acid and bicarbonate or they may utilize any type of sequestered reactants which can generate gas on being activated. The activation can occur by pressing the layers so as to crush the microcapsules or other activation means may be employed. When the gas is generated, the material swells causing the layers to separate. The layers will normally be sealed so as to prevent the loss of gas.  
         [0039]     In each of these cases, the distance between the two layers of the container is increased. For example, in the embodiment of  FIG. 1 , the compressed state may have a thickness of 0.08 inches while the expanded state may have a thickness of 0.20 inch. In the embodiment of  FIG. 3 , the stored state may have a thickness of 0.006 inch and an expanded state of 0.2 inch. Likewise, other embodiments may have a similar size changes. The particular stored thickness and expanded thickness may vary due to physical limitations in the various constructions. However, it should be noted that the difference in thicknesses allow for the container to be stored in a much smaller area. This difference is incredibly important, especially for a small establishments where the amount of storage space is very limited.  
         [0040]      FIGS. 6 and 7  show other arrangements for expanding the two layers, based on a screw mechanism. In  FIG. 7 , the outer layer  60  contains a protrusion  64  having screw threads around its outer periphery. The inner layer  62  contains a recess  66  also containing screw threads. The two layers can be screwed together to make a compact unit. When the container is being used, the two layers are unscrewed relative to each other to provide an air separation therebetween.  
         [0041]      FIG. 8  shows a similar arrangement, but where the outer layer  70  has screw threads  74  formed in the sloping sidewalls of this layer. Inner layer  72  similarly has screw threads on the outside of the sidewall which engage the screw threads  74 . The screw threads can extend circumferentially so as to engage around the entire periphery of the layer. When the inner layer is turned relative to the outer layer, the screw threads cause the inner layer to be lifted relative the outer layer causing an increase in the air spacing.  
         [0042]      FIGS. 9-11  show additional embodiments based on the use of an accordion section which is used to couple the two layers together. In each of the three figures, the outer layer  80  and the inner layer  82  are joined by an accordion section  84 ,  86  or  88 . This section can be similar to those used for drinking straws which can be expanded by being pulled. Thus, in  FIG. 9 , the two walls are joined at the top by accordion section  84 . In  FIG. 10 , the two walls are joined by accordion section  88  which is mounted between the bottoms of the two layers. In  FIG. 11 , accordion section  88  is formed on the sidewalls of the outer layer only. In each of the three embodiments, the container can be expanded by pulling the inner layer upwardly in order to expand the accordion section and separate the two layers.  
         [0043]      FIGS. 12A and 12B  disclose a variant of the accordion arrangement. As seen in  FIG. 12A , the two layers have walls which are formed with corrugations. The inner layer is a load carrying layer manufactured of a strong dense polymer such as polyethylene. An outside layer is formed from a polymer film such as polyethylene which covers the inner layer and follows the shape of the inner layer. Both walls have corrugations which nest in order to minimize the containers size during transportation. When the container is used, a special ring-shaped protrusion near the bottom holds the outer layer away from the internal load carrying container layer as the container is unfolded. Thus, before the container is expanded, the external polymer film lies against the surface of the inner layer. The employee then moves the corrugations of the container apart until the required volume is obtained. The separating corrugation at the container bottom is unfolded which stretches the external film and moves it away from the inner layer. Thus, the inner layer is pulled upwardly to unfold the corrugations which then causes the external film to be stretched. Thus, the separation between layers is formed to acquire insulating properties.  
         [0044]      FIGS. 13A and 13B  show another arrangement where corrugations are utilized in order to completely fold the container. In a similar fashion to the arrangement of  FIGS. 12A and 12B , the load carrying layer is deformed and wrapped with a layer of polymer film. The container is shaped into a plane using the corrugations and folded. The folded body may then be inserted into the container lid which is folded in two. It is also possible to insert elastic elements with equal spacing into the folding lines of the body and lid which will act as springs. When the container is removed from the lid, the springs, as well as the elasticity of the material will allow the container lid to reacquire the original shape. The bends in the lid and body have protrusions that separate the external film from the inner layer in the same fashion as in the arrangement of  FIGS. 12A and 12B .  
         [0045]     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.