Abstract:
The present disclosure provides a multiple-compartment insulated food tray and lid for storage and service. The insulated food trays allow for two or more stacked strays to be mechanically unified using the weight of the top tray on the bottom tray in any orientation where the weight of the second tray remains on the first tray. In another embodiment of the present disclosure, a polymer with foam and blowing agents are used during the molding process to create in a first phase a hard shell in contact with the mold. In a second phase, insulation is created in the hard shell by thermal treatment and expansion of the residual polymer inserted in the mold. In a third embodiment of the present disclosure, the insulated food trays, when stacked, can be placed in a nondiscriminatory arrangement.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 11/423599, filed Jun. 12, 2006, the contents of which are hereby incorporated herein by reference. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates to a multiple-compartment insulated food tray for storage and service, and more particularly an insulated food tray and method of manufacture using a durable polymer matrix wherein each main compartment is insulated. 
       BACKGROUND 
       [0003]    Meals served to humans generally include multiple courses served at different temperatures. Normally, each courses is served on a different plate, often at different temperatures, and at different time intervals. In some circumstances, large groups of people must be fed where special requirements are imposed. In some environments, such as school cafeterias, incarceration facilities, hospitals, military bases, summer camps, airplanes, nursing homes, etc., food service must be provided to large groups without generating excessive dirty dishes or utensils, and those dishes and utensils must limit manipulation problems at service, provide ease in storage, be easily cleaned, protect the user from sharp objects, and even respect strict logistical restraints. 
         [0004]    The use of food serving systems based on trays is known in the art. The first generation of trays was made of disposable structures with removable inserts. More robust trays include a light-weight frame with vertical separators designed to segregate the courses, but these trays offered little or no thermal insulation between the courses. A common example of these trays include the familiar TV dinner tray, which is able to hold frozen food for long periods of time and later be placed in a conventional oven. Trays may include compartments to separate cold foods from hot foods, wet courses from dry courses, and prevent mixing of the courses. Trays may also include compartments in which small items such as condiments can be served. 
         [0005]    Thin-walled metallic trays are light and disposable but offer little temperature control of the food. If heated courses are placed in these trays, the trays themselves can become hot, the hands of users can be burned, and food courses can reach thermal equilibrium within minutes. Newer versions of trays include insulation placed within a shell made by the tray, but these shells are often bulky, require numerous and expensive manufacturing steps, result in very small compartment sizes, and are still vulnerable to thermal equilibrium unless they are covered by a second tray or a lid. For this reason, a thin-walled robust food tray capable of insulating the food is needed. 
         [0006]    Another problem with existing trays is the incapacity to provide for an efficient and safe way to supply of utensils without resulting to a dedicated compartment in the tray, or an independent and external supply of utensils. Placing utensils within a compartment often results in the utensil being in contact with the food. What is needed is a food tray able to provide for utensil delivery system without negatively affecting the other functions of the food tray, such as the capacity. 
         [0007]    Yet another problem of existing food tray technology is partial insulation resulting from stacking trays. Food place within a recessed portion of a first insulated food tray is insulated from the environment, but if the courses include hot and cold portions located in different compartments, both courses reach an intermediate thermal equilibrium quickly within the food tray. What is needed is a compartment-specific insulated food tray. The use of compartment-specific insulation may also offer odor control in order to better preserve the aroma of each course. 
       SUMMARY 
       [0008]    It is an object of the present disclosure to provide an insulated, multiple-compartment food tray and lid for storage and service. The insulated food tray and lid is equipped with a circumferential, weight-activated lip and a series of female U-shaped lips located on the tops of the internal and external walls of the insulated food tray. If a lid or a second insulated food tray acting as a lid is placed on top of the first insulated food tray, an L-shaped circumferential lip and male U-shaped lip located on the bottom portion of the second tray seals the compartments from each other resulting in thermal and aromatic segregation among the compartments. The use of a long, L-shaped lip on the circumference of the insulated food trays allows for two stacked strays to be mechanically unified using the weight of the top tray on the bottom tray in any orientation where the weight of the second tray remains on the first tray. 
         [0009]    In another embodiment of the present disclosure, a polymer with foam and blowing agents is used during the molding process to create in a first phase a hard shell in contact with the mold. In a second phase, insulation is created in the hard shell by thermal treatment and expansion of the residual polymer inserted in the mold. This two-step formation process allows for a light, robust insulated food tray with better capacity and improved properties over existing food tray technologies. In a third embodiment of the present disclosure, the insulated food trays can be stacked in a nondiscriminatory arrangement by rotating one tray in relationship with the next by a fixed angle depending on the geometry of the insulated trays. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an exploded view of a stack of two insulated food trays and a top lid in accordance with an embodiment of this disclosure. 
           [0011]      FIG. 2  is a side view along cut-line  2 - 2  of the exploded view of the stack of two insulated food trays and the top lid of  FIG. 1 . 
           [0012]      FIG. 3  is a top view of an insulated food tray in accordance with an embodiment of this disclosure. 
           [0013]      FIG. 4  is a bottom view of the insulated food tray of  FIG. 4 . 
           [0014]      FIG. 5  is a detail cut view of the L-shaped lip of an assembled stack of insulated food trays and a top lid in accordance with an embodiment of the present disclosure. 
           [0015]      FIG. 6  is a detail cut view of the U-shaped lip in the assembled stack of insulated food trays and top lid in accordance with the embodiment of  FIG. 5 . 
           [0016]      FIG. 7  is a functional diagram in accordance with a method of manufacturing an insulated food tray in accordance with an embodiment of this disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to  FIG. 1 , a stack  16  of insulated food trays  1  and lid  2  is shown. In this possible embodiment, two insulated food trays  1  are shown stacked vertically, and a lid  2  is placed on top of the upper insulated food tray  1 . It is understood by one of ordinary skill in the art that while only two insulated food trays  1  are illustrated, a stack can include a greater plurality of insulated food trays  1 . 
         [0018]    The bottom insulated food tray  1  as shown on  FIG. 1  is arranged nondiscriminatorily in relation to the top insulated food tray  1  and can be rotated in the horizontal plane by 180 degrees. While a single nondiscriminatorily arranged configuration is illustrated in  FIG. 1 , it is understood by one of ordinary skill in the art that many different configurations and nondiscriminatory arrangements are possible based on a plurality of factors, including the geometry of the insulated food tray  1  and the arrangement of the different inner compartments. An illustrative but nonlimiting example includes an octagonal insulated food tray with eight compartments located circumferentially around a single center compartment. In this example, a top insulated food tray  1  could be placed nondiscriminatorily in eight orientations in relation to a bottom insulated food tray  1  by rotating the top or bottom tray by any factor of 45 degrees. 
         [0019]      FIG. 2  shows an insulated food tray  1  of  FIG. 1  comprising an upper surface member  3  of a first height  51  and a lower surface member  4  of a second height  53  connected to the upper surface member  3  to form an outer shell  21  with an inner volume  20 . An insulated material is released in the inner volume  20  in a phase of the formation process of the insulated food tray  1 . 
         [0020]    The inner volume  20  is filled with an insulating medium as a result of the formation process of the outer shell  21 . An injection molding method for manufacturing an insulated food tray is shown in  FIG. 7 . In a first step  101 , a series of agents are blended into a polymer in order to create a durable polymer matrix. A quantity of blowing agent is added to the mix. In a preferred embodiment, a range of 1% to 5% of weight is added. It is understood by one of ordinary skill in the art that while a preferred range is disclosed, the determination of the quantity and proportion of blowing agent to be added to a mix is a function of the chemical nature of the blowing agent and the chemical stability of the base polymer as processed during molding by the injection mold and associated molding apparatus. A quantity of structural foam is also added to the polymer mix. In a preferred embodiment, the range is 5% to 20%. It is also understood by one of ordinary skill in the art that as for any other agent added to the polymer mix, the determination of the quantity and proportion of structural foam needed are a function of the chemical nature of the foaming agent and the chemical stability of the base polymer in combination with any other agent as used during the process of molding by injection. In a second step  102 , the durable polymer matrix is injected into the mold using conventional injection molding techniques. It is understood by one of ordinary skill in the art that the precise amount of durable polymer to be injected is a function of the actual geometry of the insulated food tray and the expansion volume of the insulation  20  within the inner shell  21  and must be calibrated upon injection based on the parameters of the injection molding device. 
         [0021]    In a third step  103  also shown in  FIG. 7 , the polymer matrix is solidified on the outer surface of the insulated food tray in order to form an outer shell  21  in contact with the cold, inside surface of the injection mold. It is understood by one of ordinary skill in the art of injection molding that the thickness of the shell and the injection locations in the mold needed to form the plurality of ribs and structures of the insulated food tray  1  are calibrated using classical injection molding techniques. In a fourth step  104 , a fraction of the polymer matrix remaining inside the shell is heated to allow the endothermic or exothermic durable polymer matrix to generate gas to form a solid insulation material with small gas bubbles. In a preferred embodiment, nitrogen gas is released during an endothermic reaction, but it is understood by one of ordinary skill in the art that any type of release gas chemically activated during the heating phase may be used, as well as any other neutral gas or expansion solid. It is understood that activation of the foam agent and the blowing agent by heat or other activation source is a very broad technology. What is contemplated is any activation means including but not limited to heat, cold, friction, time, chemical by-products, electrical current, magnetic excitation, irradiation, vibration, and any other potential energy source able to activate an agent found within a polymer matrix and create an insulation phase. In a preferred embodiment, the heating phase is conducted during approximately six minutes and at a temperature of approximately 140 degrees F. It is understood by one of ordinary skill in the art of heating injection molded pieces that the temperature and duration of the heating phase are a function of a plurality of parameters needed to activate agents within the polymer matrix and correspond to the current best mode. 
         [0022]    The next step of the method of manufacturing relates to cooling the insulated food tray within the injection mold  105 . In a preferred embodiment, water is used to cool the mold to facilitate stabilization of the agents and the insulation  20  within the outer shell  21 . It is understood by one of ordinary skill in the art that the insulated food tray  1  within the injection mold can be cooled using a plurality of conventional means including but not limited to air cooling, mold cooling, time cooling, and compressed gas cooling. In a next step, the insulated tray  1  is stabilized  106  before removal from the injection mold using classical techniques including but not limited to hand removal or mechanical removal. 
         [0023]    Returning to the embodiment shown as  FIGS. 1 and 2 , the upper surface  3  of a first height  51  and the lower surface  4  of a second height  53  are shown to be the same height corresponding to roughly half of the total height of the insulated food tray  1 . It is understood by one of ordinary skill in the art that while first and second heights  51 ,  53  are shown in this proportion in a preferred embodiment, the respective heights can correspond to any proportion of the total height of the insulated food tray  1  as long as the functional limitations associated with stacking the insulated food trays  1  is made possible. 
         [0024]    The upper surface member  3  is relieved to define a plurality of inner compartments  5  of at least a third height  50  of a first top lip  57  and an outer rim  7  [not shown] with a second top lip  55  of the first height  51 . The lower surface member  4  is relieved to define inner ribs  58  of a fourth height  52  with a first bottom lip  56  and a second outer rim  14  [not shown] with a second bottom lip  54  of the second height  53 . While the surface member  3  is described with the help of elements of two heights called a first height  51  and a third height  50 , respectively, it is understood by one of ordinary skill in the art that both heights may be of the same height or that any of the two heights may be higher from the bottom surface of the compartments  5  without any influence on this disclosure. The same may be said for the second height  53  and the fourth height  52  on the bottom member  4 . The use of the terms “second” and “fourth” are not indicative of the necessity of a difference in height or any indication that the second height  53  is more important than the fourth height  52 . 
         [0025]    The contents of an inner compartment  5  in a first insulated food tray  1 , as shown in  FIG. 3 , is insulated by another inner compartment  5  in the first insulated food tray  1  by placing a second insulated food tray  1  on the top of the first insulated food tray  1  so the first bottom lip  56  and the second bottom lip  54  of the second insulated food tray  1  connects with the first top lip  57  and the second top lip  55  of the first insulated food tray  1 , respectively.  FIGS. 5 and 6  show two detail of the embodiment of  FIGS. 1 and 2  where both bottom lips  56 ,  54  of the second insulated food tray  1  connect with both top lips  57 ,  55  of the first insulated food tray  1 . It is understood that while the present disclosure relates to an embodiment where the combined height of the first and second heights  51 ,  53  must be approximately the same as the combined height of the third and fourth heights  50 ,  52  in order to seal the compartments  5 , other heights may be contemplated that are sufficient to seal the compartments  5 . It is be understood by one of ordinary skill in the art that while the best mode of a preferred embodiment disclosed is made of a single molded element, the art of injection molding allows contemplation of the use of the merger of more than a single molded element in order to create the preferred embodiment. A nonlimiting example includes the use of a first upper surface member  3  of a first height  51  wherein a series of smaller containers would be connected to the inside portion of the relieved portion of the upper surface member in order to recreate containers  5 . The present disclosure contemplates the use of any combination of elements in order to create the essential properties of the insulated food tray disclosed herein. 
         [0026]    In another embodiment, the seal between the first top lip  57  is made of a female U-shaped lip, and the first bottom lip  56  is made of a male U-shaped lip in order to allow for the compartment  5  to be sealed when the upper surface member  3  of a first insulating food tray  1  is placed under the lower surface member  4  of a second insulated food tray  1 . In another preferred embodiment, the second top lip  55  is made of a male U-shaped and the second bottom lip  54  is a recessed L-shaped lip. In the preferred embodiment shown as  FIGS. 1-6 , the L-shaped lip is inverted and the top portion of the L-shaped lip is located inside of the volume formed by the second top lip  55  of the first insulated food tray  1 . It is understood by one of ordinary skill in the art that while U-shaped and L-shaped lips are disclosed and shown, these shapes may be made of a series of flat or curved sections assembled to recreate these shapes. It is understood that the maximum angular radius of any connecting angle is determined by the manufacturing process and molding tolerances associated with the molding process. In a preferred embodiment, the lips  56 ,  54  are approximately ⅛th inch in lateral thickness and the U-shaped lip and L-shaped lip have a quasicircular head radius and a very thick wall. 
         [0027]    As shown on  FIG. 4 , support corner tabs  11  are placed on the bottom section of the L-shaped lip  54 . These tabs serve a plurality of functions including but not limited to improving locally the coverage section between both insulated food trays in a stack  16 , and protecting the first bottom lip  56  from friction and wear when the insulated food tray  1  is placed on a table or other surface. In a preferred embodiment, the support corner tabs are about 1/16th inch in height. It is understood by one of ordinary skill in the art that a plurality of support mechanisms can be used to protect the first bottom lip  56  from wear. 
         [0028]    One of the compartments  5  includes a notch holder  12  able to receive a utensil  60  as shown using phantom lines in  FIG. 1 . The notch holder is designed to hold a utensil  60  specifically designed to be used in conjunction with food courses served within one or more of the compartments  5 . In a preferred embodiment, the handle of the utensil is inserted in the notch  12  in order to protect the apprehension section of the utensil  60  from coming in substantial contact with food placed in the compartment  5  where the utensil  60  is situated. 
         [0029]    In yet another embodiment as shown in  FIGS. 1-2 , the upper surface  3  of the insulated food tray  1  is further relieved to create two side-by-side volume separators  13 . In a preferred embodiment, the volume separators  13  define condiment holders to be used in association with one of the courses placed in the containers  5 . It is understood by one of ordinary skill in the art what while two volumes are shown, different quantities or types of volumes may be contemplated. In addition, in the preferred embodiment shown, the third height  50  of the condiment sections  13  does not include a first top lip  57  to be associated with a first bottom lip  56  of an associated fourth height  52  of a second insulated food tray  1 . This configuration contemplates use where the condiment compartments  13  are not completely insulated from the surrounding immediate compartment  5 . It is understood by one of ordinary skill that any combination of sealed or unsealed first bottom lip  56  may be used in association with this disclosure depending on the desired level of insulation to be obtained. 
         [0030]      FIG. 1-2  illustrates a situation where a first insulated food tray  1  is insulated by placing a second insulated food tray  1  on top. The figures also show the situation where the second insulated food tray  1  is insulated by placing a lid  2  on top. The lid comprises a second upper surface member  17  and a second lower surface member  18 . The lower surface member  18  is relieved to create a series of ribs  22  to mimic the lower surface  4  of the insulated food tray  1 . In the preferred embodiment, the second upper surface member  17  is flat, but it is understood by one of ordinary skill in the art that the lid may be made of a wide variety of geometries and include numerous functional features to serve any additional purpose. 
         [0031]      FIGS. 1-2  show an exploded view of the tray stack shown in  FIGS. 5-6 . When trays and/or a lid are stacked, the weight of the top trays, along with the weight of the food courses placed in the compartments  5 , serve to seal the bottom insulated food tray  1  with the top insulated food tray  1  or lid  2 . It is understood that if an insulated food tray is insulated and sealed by gravitational force, the seal may be broken if the stack  16  is rotated to a significantly vertical configuration. The disclosure provides for a stack of trays able to remain sealed as long as the weight of the top insulated food tray  1  or lid  2  pushes on the bottom insulated food trays  1 . 
         [0032]      FIG. 3  is a top view of an insulated food tray in accordance with an embodiment of this disclosure.  FIG. 4  is a bottom view of the insulated food tray of  FIG. 4 .  FIG. 5  is a detail cut view of the L-shaped lip of an assembled stack and top lid of insulated food trays in accordance with an embodiment of the present disclosure.  FIG. 6  is a detail cut view of the U-shaped lip in the assembled stack and top lid of insulated food trays in accordance with the embodiment of  FIG. 5 . 
         [0033]    Persons of ordinary skill in the art appreciate that although the teachings of the disclosure have been illustrated in connection with certain embodiments, there is no intent to limit the invention to such embodiments. On the contrary, the intention of this disclosure is to cover all modifications and embodiments falling fairly within the scope of the teachings of the disclosure.