CA1230085A

CA1230085A - Food container and the process for initiating the production of integrated heating of same

Info

Publication number: CA1230085A
Application number: CA000415063A
Authority: CA
Inventors: Simon Benmussa
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-11-09
Filing date: 1982-11-08
Publication date: 1987-12-08
Also published as: EP0079286A3; EP0079286B1; ES8307471A1; MC1484A1; EP0079286A2; ES517213A0; DE3280138D1; IL67190A

Abstract

ABSTRACT OF THE DISCLOSURE
A self-heating receptacle is provided herein comprising a vessel for food to be heated, and below the vessel, a container sealed by a lid. The container contains two chemicals, e.g.
quicklime and water, which are reagents for an exothermic reaction. A pouch within the container holds one of the chemicals sealed from the other. A flexible tearing filament secured to the pouch is for simultaneously opening both the pouch and the container, thereby to trigger the exothermic reaction to heat the food vessel. The tearing filament is so connected to the pouch and is so arranged that, upon pulling the tearing filament, the tearing filament creates a line of tear across both the pouch and the lid.

Description

3~ 35 The invention relates to a food container and the process for initiating the production of integrated heating of same.
Numerous self-heating containers exist at the present time.
These containers have numerous drawbacks. One drawback is that it is difficult to store these containers for several days. Another drawback is that reactive products, not being protected efficiently in a packing, becomes inoperative in course of time, in general after fifty to seventy days. Furthermore, the means used for starting the chemical reaction which produces the heat for heating the foods are more or less efficient.
Generally, these containers are provided with several reactive pockets, a pocket containing calcium oxide or quicklime, or potassium hydroxide and orthophosphoric acid or calcium oxide or quicklime and a water pocket, a means being provided for bursting these pockets to allow the reaction. The pocket is disposed in the upper part which causes a rapid but limited exothermic reaction because of the poor mixing which is obtained between the water and the reagent.
Numerous patents exist which describe self-heating containers.
I~owever, their present design imparts serious disadvantages thereto, namely poor combustion of the quicklime, and premature or accidental setting off of the reaction, which may be dangerous.
German Patent 1,214,600 waS conceived for a well defined mixture of fruit juice and milk, and does not then include the use of reactive mixtures.
Likewise, U.S. Patent 3,085,681 cannot serve in this type of use without risks. The water must necessarily be in the inner pocket, and the water cannot impregnate the quicklime entirely because of the very ~23~

arrangement of the two envelopes - resulting in poor combustion of the quicklime. Moreover, the outer pocket would explode under the vapor pressure released by the quicklime at the time of the reaction, and if that would not occur, the vapor would remain enclosed and so would not in any case heat the foods in a third container.
U.S. Patent 3,871,357, in so far as opening of the water pocket is concerned, only opens it once out of three or four times - for both the pocket and the tongue are free in its commercial application. Even in the patent, the risks of insecurity are great, since a cutting blade on the tongue may, if the foods are heavy, cut the tray containing them or burst it with actuating the tongue, in the stopped position and if there is any juice at all, the reaction would be immediately triggered off. When moving the tray, the water pocket may burst by itself by banging against the tip of the tongue, resulting in uncontrolled triggering off of the reaction.
In French Patent 2,348,121, the adhesive strip forms an hermet-ic seal for a water pocket. This is irrational for the least humidity, or heat which is too high,or temperatures which are very low,may unstick the adhesive strip. The reaction would take place at any time and would be uncontrolled. In this French Patent 2,348,121, the water pocket is fixed at one end and the cord is independent of the pocket at another end. That allows a certain movement within the heating tray, which results in a certain risk of tearing and of an uncontrolled reaction of the reagent during production, storage, transshipment or transport thereof.
A Swiss process, known under the name of Trade Marks of POZEL, BLANC~IAT and BERTRAND is commercialized. The self-heating containers of such process are identical in design in so [ar as the assembly of the ~23~

troughs and the unit so Lormed is concerned, to U.S. Patent No. 3,871,357 and to the above-mentioned U.S. and German Patents as well as to French Patent 2,348,121 for the opening of the water pocket. This latter is stapled by one end to a small cardboard sheet as well as the opening cord which, while being independent of the pocket, is also stapled at one end to said cardboard. The whole is free to move without anchorage in the heating trough thus resulting in a permanent danger caused by the staples which may either tear the trough receiving the foods, and thus the juice would trigger off a reaction, or also pierce the heating trough and even the water pocket, which would cause the reaction at an ill-timed moment.
It should also be noted that in all these above-mentioned patents, the quicklime is also in constant movement inside the heating trough-resulting in poor operation through lack of total combustion or combustion at a single location in the trough which, thus, does not allow perfect heating of the food contained in the upper trough where, very often, a single part is hot.
Furthermore, existing troughs have a flat water pocket covering practically the whole of the heating surface, which forms a screen for the diffusion of heat to the upper trough containing the food.
The standards in force are embodied in legislation relating to packing, safety and hygiene. In the existing self-heating containers an assembly is provided between the trough containing the foods and the flexible aluminum foil serving as heating trough in which are incorp-orated the quicklime and the water pocket. Thus, since the trough receiving the foods never exceeds 80 microns for financial and technical folding reasons, accidents may be Feared due to faulty handling by the user either in piercing the bottom of the food tray, then the juice of the meal would ~Z~ 5 pause a reaction with the quicklirne, or by bursting t:he wat:er pocket, the same resul.t ooul.d be attained.
n object therefore of one aspect oF this irluelltion is to giue the user all the guaran~ec!s of hygi.ene and saFety without losing efficierlcy.
n object of another aspect of this inuenti.on is to prouide an irnprouernent in the triggering-off of the reaction (which is always controlled), to prouide a substantially complete reaction of the reactant products, and an hornogeneous 0 heating of the food products.
y one broad aspect of this inuention, a self-heating receptacle is prouided comprising a uessel for food to be heated, and below the uessel, a container sealed by a lid, the container containing -two chemicals which are reagents in an exothermic reaction; a pouch within the container in which one of the chemicals is sealed from the other chemical; and a flexible tearing filament for simultaneously opening the pouch and opening the container, thereby to perrnit the chemicals to contact each other and to take part in the exothermic reaction thereby to heat the food uessel; the tearing Filament being connected to the pouch and being so arranged that, upon pul].ing the tearing filarnent, the tearing filament creates a line of tear across both the pouch and the lid.
The pouch is preferably suspended by its encis aboue the bottom of the container and is surrounded by the ~3~

chemicals. In this embodiment, the ends of the pouch are secured to upwardly-facing ledges on the container.
In another aspect, the self-heating receptacle is provided in combination with a housing in the bottom of which the container is disposed, the food vessel being disposed in the housing on top of the container. The food vessel preferably has a bottom that is spaced a short distance above the upper surface of the container. In this embodiment, as well, the tearing filament extends across the lid below the bottom of the food vessel, and emerges from between the housing the food vessel in a portion that can be grasped by the user to pull on the tearing filament, thereby to split both the pouch and the lid. The flexible tearing filament preferably terminates in a free end disposed in an outwardly opening recess in the container, and includes a removable protective sheet closing the recess.
In another aspect, the chemical in the pouch is water containing an anti-freeze additive, preferably where the anti-freeze additive is either methylated spirits or ethylene glycol.
The self-heating receptacle may also include valve means coupled to the pouch for controlling the flow ox water and the development of the exothermic reaction.
The pouch in another aspect is in the form of a pouch which includes a central compartment containing wacer, and a peripheral compartment containing quicklime or calcium hydroxide.

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In yet another aspect, the self-heating raceptacle include a support trough, the support trough containing the pouch at the bottom thereof, and the food vessel being disposed thereabove, with a cover of the support trough being arranged between the pouch and the food vessel. It is preferred that an ampty space of 5 millimeters be provided between the pouch and the food vessel, the empty spaca increasing the heating capacity of the self-heating receptacle. In such case, the lid is formed from two walls, and includes fixing means allowing the lid to be fixed on the support trough, and allowing communication with the chamber formed by the bottom of the food pouch and the top of the pouch.
In still another embodiment, the self-heating receptacle includes means disposed about the two chemicals for preventing the formation of frost during the thawing of the self-heating receptacle. For example, the chemical for reaction may be quicklime and the quicklime is vacuum packed in a sealed envelope, or in an antifreeze envelope, or in an absorbing envelope so as to avoid dripping or thawing of frost which has been formed inside the pouch and which would prematurely set off the reaction of the quicklime duriny the period of thawing of the foods.
The compartment receiving the foods may be 80 microns or more in thickness, but is separated from the heating compartment (containing the pouch) by an empty space of 5 mm. A safety cover ~23~

for the heating compartment is provided having a thickness of 40 microns. The user is thus protected Erom any accidental operation by means of a thickness of 120 microns plus 5 mm of space.
During the reaction and once the reaction is accomplished, the safety cover remains on the heating compartment, the opening cord only causing a cut in the width of the haating pouch at the center thereof in the longitudinal direction, to let the steam escape which will heat the compartment containing the foods.
Means allow the reaction products to be kept for thirteen to fourteen months. Means for opening the pouches allow a progressive and total chemical reaction to be obtained. Finally, according to variations of the invention, the container may comprise means for re-using it or, on the contrary, it may be thrown away. The water pouch may include valve means for controlling the flow of water so as to control and, if need be, to stop the reaction.
The container of an embodiment of the invention disclosed and claimed in a division application hereof is formed of a support which comprises one or more compartments for the food product or products, and a compartment for the reagent mounted on slides in the manner of a drawer, the exothermic reaction being initiated by permitting mixing of the reactive products with water. To this end, the support includes an opening whose inner tides comprise slides which allow the drawer containing tha we .

~L23~)~8~i reagents to slide and to be placed in the support. A contusive or cutting means, disposed at the entrance of the opaning, opens the water pouch and causes the mixing of the reactive products.
The self-heating receptacle, according to aspects of the present invention, is designed so that the support member or food vessel holds and protects the food. Disposed below the food vessel i5 the heating vessel, or more accurately, the food vessel, that is the vessel that contains the products which are to be reheated is above the heating vessel. The food-carrying receptacle is, preferably, of aluminum foil to have a good contact with the heating receptacle which is below. The pouch which contains the water is a sleeve which is supported at its ends on supports in such a manner that the water pouch is suspended above the bottom, and a short distance from the heating vessel. That suspension of the water pouch or sleeve permits a good distribution of the water throughout the chemical, e.g. the quicklime, at the moment ox opening.
A tearing filament is provided which has two distinct functions. The first is to open the water pouch to set off or trigger a reaction, and the second is to open the lid on the heating vessel to permit the heating of the food contained in the upper vessel.
The water pouch may be made from several materials ensuring good securement. These materials must offer a completely sealed barrier to tha risks of OG~in~, sweating or dampness. Varnished . ", .
,~ ,j ~3~5 polypropylene film may -thus be used. This is a special polypropylene with very high tear factor. Alternatively, films of high or medium density polyethylenes, polyester/polyethylene or polyethylene/polypropylene complexes, all with a high tear factor, may also be used.
Contrary to the teachings of the prior art, the water pouch is flanked in the longitudinal direction in the center of the lower wall, by a tear tongue, strip or cord, of a length seleced depending on the dimensions of the water pouch, the heating compartment and on the chosen opening mode. The tear cord is bonded, heat welded or fixed to the pouch and the material out of which it is made depends not only on that of the pouch, but also on that o the closing cover. It must allow the latter to provide a complete seal, without adhering to the cover. The tear cord must have a length sufficient to come back to the rear and to project from the support trough through an orifice whose position and diameter are specially chosen and also serving as vapor discharge chimney, this orifice being closed during storage.
As noted hereinabove, the tear cord is bonded, heat welded or fixed to the outside on the lower side of the pouch. At thel front ends of the water pouch and the cover, on each side of the tear cord, a tear tab is provided so that, by exerting a pull on the cord which is placed in the center o the pouch and the cover, a part equai to its width or to its diameter is removed ~3~

l O
from the cover as well as from the water pouch, smoothly and continuously. This removal of material, due to the pull exerted on the cord, allows the water pouch, whose lower and upper walls have been subjected to this total and even cutting of a strip from the walls, to discharge the water evenly, totally and rapidly because of the few tenths of millimeters of space left between the pouch resting on the pads and the bottom of the heating compartment, that is to say due to the tact that the water pouch is suspended by its end in the bottom of the heating compartment. Because of the piece cut out of the cover and the total removal of a strip equal to the width of the tongue, this invention allows the vapor created by the exothermic reaction to escape. Thus the foods contained in the upper compartment are heated without reducing the safety due to the thickness of the cover which remains in position.
In the teachings of the prior art, the tongue or cord has only one function and one use, namely it tears a wall or a pocket so as to cause mixing. On the contrary, in the present invention, in its broadest aspects, the tearing cord has two separate functions: the first function being for opening the water pouch so as to trigger off the reaction; the second function being to open the cover so as to allow heating of the foods contained in the upper trough. In many self-heating receptacles in use at the present time, the cover which separates the heating trough from the food trough does not exist.

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Since only a small strip is removed from the cover for allowing the vapor to pass therethrough, the cover is permitted to continue its protection function in so far as safety and hygiene are concerned.
The invention in another aspect also provides novel means for triggering off the reaction. The tearing cord used in accordance with embodiments of the invention is fixedly secured to one of the ends of the water pouck, then it passes between the upper part of the water pouch and the lower part of the cover, then between the upper part of the cover and the bottom of the food trough. The cord forms an "S" or a "V" which, in a first stage, tears the safety cover and, in a second state, opens the water pouch.
For products which are deep-frozen, the heating trough used in accordance with aspects of the invention provides further technical advantages. Thus, the water of the pouch has an anti-freeze product, e.g., methylated spirits or ethylene glycol added thereto, sufficient for reaching minus 40C. without undergoing any physical change. The ractant chemical, e.g. the quicklime, is also vacuum packed in the trough but it must be protected from contact with the aluminum by an envelope made from polystyrene or from any anti-freeze and/or absorbent material or complex. When the foods are thawed and during the whole time required for this operation, the dripping of moisture from the frost which would form inside the heating trough does not start a premature reaction with the quicklime. The invention in its various aspects provides both a disposable container and a refillable container, as well.
In more general terms therefore, the invention in a first embodiment of a disposable self-heating receptacle, comprises a support member supporting one or a plurality of food vessels. A
container disposed below the receptacle carries the reactive chemical products, which can be quicklime and a reservoir of water in a pouch. The container is sealed hermetically by an impermeable but frangible lid.
The food vessel can be 80 microns or more in thickness, and is separated from the heating vessel by a gap of 5 mm. The lid of the heating vessel may be up to 40 microns in thickness.
During and after the reaction, the lid rests above the heating vessel. By pulling the tearing filament, which extends beneath one edge of the lid and is secured to the pouch, the pouch is torn open and its water mixes with the quicklime to initiate an exothermic reaction that produces steam. The lid is cut along its center in the longitudinal direction to allow the escape of steam, which heats the food vessel.
A protective sheet is disposed on the side ox the support member, and inside this sheet is disposed the end of the tearing filament, so that by remoYing the sheet and by reaching into the recess in which the end of the tearing filament is disposed, grasping that end and pulling on the tearing filament initiates ~l~3a~35 the operation described above. The lid is of water impermeable material, e.g. polystyrene, such that frost which forms on the food vessel during freezing, will not, upon thawing and the consequent formation of moisture, trigger the premature reaction of the quicklime.
In another embodiment, the heating vessel includes the quicklime therein and a sleeve or pouch of water. The pouch of water is suspended by its ends which are secured on ledges of vessel, above the bottoml of the heating vessel. A tearing filament is also provided. The tearing filament is secured at one end of water pouch and passes below the pouch between the pouch and the bottom, beneath the end between the edge of vessel and the lid, and then above the lid.
The food vessel is supported by its rim on the upper rim of the upper vessel above the lower vessel. The bottom of the food vess,Pl is spaced above the lid of the heating vessel, and the tearing filament extends through this space, and then between the rims of the vessels and emerges to provide an end that can be grasped and pulled by the user. When this is done, the filament tears the lid loose from the haating vessel, and then begins to split the water pouch beginning at one end thereof. The simultaneous splitting of the lid and the water pouch not only opens the pouch but also serves thoroughly to mix the water from the pouch with the quicklime, thereby to provoke an exothermic reaction releasing steam. At the same time pulling on the ~3q~

filament splits the lid, thereby to permi-t this steam to contact and heat the bottom of the food vessel. The fastening of one end of the pouch to the ledge ensures that the filament will split the pouch beginning at that end, and that thereafter, the filament so distorts the pouch as not only to expel the water contained therein but also to tend to mix that water thoroughly with the quicklime.
In another embodiment, the cover is made of two parts.
Space is provided between the two parts to serve as a chamber for lO hot vapours from the heating vessel. The cover is provided with small conduits or chimneys which are disposed in communication with a chamber formed by a bottom of the food carrying vessel and the lid of the chamber of the heating vessel. When the filament is pulled, it exerts a force on the secured extremity of the pouch, thereby rupturing the pouch. At the same time the cord tears or peels away the lid on the heating vessel. The piercing or removal ox the lid allows the steam to enter into the space between the lid and the bottom of the Good vessel. The steam also enters the chamber and rises through the conduits into the 20 space between the two parts of the cover. In this fashion heat is provided on all surfaces of the recaptacle.
In certain northern climates, where temperatures can reach -15C. or -20C., it is difficult to reheat the food conveniently when using a conventional receptacle. The foods at the bottom will -worm and those at the top will be cold. To avo.d .
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such problem, the cover can be made of two walls, the exterior of polypropylene and the interior of polypropylene fused onto aluminum. In between the two walls is a space, which in turn is in communication with the heating chamber of the vessel. The vapour passes over the cover and reheats all of the food in the food-carrying vessel or container equally and sufficiently.
The refillable receptacle is designed mainly for being used by private persons (campers, yachtsmen, etc.) for whom the preparation of dishes is different from that of others and often requires whole pieces of meat, e.g., fillets or quiche lorraines, pizzas, etc. to be heated. The container further includes a cover which has three main functions:
a) that of protecting the foods and preventing them from overturning;
b) it may serve either as a dish for eating or as a cutting up dish; and c) it may also serve in some cases as a steamer.
In the accompanying drawings, Figure 1 is a perspective view seen from the side of the integrated heating container according to one embodiment of the invention disclosed and claimed in a divisional application hereof;
Figure 2 is a partial and cut away view of the drawer opening of the receptacle of Figure 1 showing the operation of the means for opening of the receptive pouches;

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Figure 3 is a sectional view of a po-lch of reactive products;
Figure 4 is a lateral view in section of a disposable container with integrated heating according to one embodiment of this invention;
Figure 5 is a lateral view in section of a disposable container with integrated heating according to another embodiment of this invention;

Figure 6 is a longitudinal sectional view of another embodiment of an integrated heating container according to another facet of this invention;
Figure 7 is a longitudinal sectional view of the heating trough on the integrated heating container according to another embodiment of this invention;
Figure 8 is a longitudinal sectional view of the protection support-trough assembly with its heating pouch and its food container; and Figure 9 is a longitudinal sectional view of the support-trough assembly according to yet another embodiment of this invention with its heating pouch and its food container and further with its lid.
The container 1 shown in Figures 1, 2 and 3 is an embodimentof the invention disclosed and claimed in a divisional application hereof, and is formed of a support 2 nhich comprises one or more compartments 3 and I. An opening 6 is provided on , ~;~3~

the wide 5 of support 2. The opening 6 allows a housing, which contains the reactive product or products, snot shown), to go in or out like a drawer 8. The reactive products, e.g., calcium oxide or quicklime and water, are separate and are packed in a sealed plastic pouch. A cutting means 9 is arranged at the entrance 6. Cutting means 9 is shown as a toothed strip whose teeth 10 engage the pouch when the product passes and allow the reactive products to be mixed. This mixing gives rise to the exotharmic chemical reaction and heating of the food produrts disposed in compartments 3 and 4. A pouch containing the reagents in compartments, in this example, calcium oxide in a peripheral compartment 11, and water in a central compartment 12, is shown in section in Figure 3. The support 2 with its opening 6 on the side 5 is shown in Figure 2. According to a variation of this embodiment, the opening 6 comprises a slit 13 in which a tongue provided on the pouches of reactive products is engaged when drawer 8 is pushed in. By pushing drawer 8 into its housing, the tongue is nipped in slit 13 and tears the reagent bag or bags, which causes the mixing and immediately sets off the exothermic chemical reaction.
The drawer 8 includes guide ramps l on its sides 14, and a vertically-movable piece 16 which is attached to cutting means 9.
Piece 16 moves in channel 17a as roller 17 is moved vertically by ramp 15. As will be noted, piece 16 is biased upwardly by spring 13. When drawer is completely freed prom its support 2, the .
~3, ~3~ 3S

teeth 10 of the strip 9 do not appear. The user places a reactive product refill in drawer 8. When drawer 8 is pushed closed, rollers 17, riding on ramps 15, move downward, forcing strip 9 and teeth 10 into the pouches of reactive chemicals in drawer 8 or vessel 18, thereby opening the pouch. After use, the expended chemicals may be removed and the unit reused by recharging it with fresh reactive chemicals. The advantage ox this embodiment is that an integrated heating container is obtained which is refillable with reactive products, and is always operative.
According to another embodiment of this invention which is a variation thereof, the integrated heating container may be disposable, as shown in Figures 4, 5 and 6. Support 18 includes one or more compartments 19 for food products. A housing 20, disposed below compartment 19, contains the reactive products 21 (calcium oxide) and 22 lthe water pouch). Housing 20 which includes the reactive products 21 and 22 is sealingly closed by cover 23.

An opening means 2~ is provided after breaking a protecting window or plate 25. Cord 26 may be pulled which opens the pouch 22 containing the water and thus causes the reaction. The pouch may also be provided with valve means serving as a non-return valve for controlling the flow of water and thus the chemical reaction and so the heating.

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In some cases, it may be advantageous -to keep the Eood container in a deep freezer so as to have deep frozen products.
In order that the water pouch does not freeze or burst, it is advantageous to add a chemical which lowers the freezing point thereof to the water, e.g., ethylene glycol or methylated spirits.
The heating trough 30, with the quicklime 31 and its water pouch 32 can be seen in Figure 7. The water pouch 32 is suspended by its ends 33 and 34, which rests on pads 35 and 36, to space water pouch 32 above the bottom 37 of the heating trough 30. A tearing cord 38 is fixed at the ends 33, 34 of peuch 32.
As seen in Figure 7, cord 38 passes under the safety cover 39.
The tearing cord 38 may also be arranged as shown in Figures 5 and 6. However, Figures 7 and 8 show the double function of the tearing cord 38. In Figure 7, the tearing cord 38 passes over the lower wall, and comes out under the end 34 between pad 36 a:nd the securing point of the pouch 3.2. In Figure 8, the tearing cord 38 leaves from end 33 of the water pouch 32, passes over the upper part of pouch 32 and under the lower wall of the cover 39, and comes against the inner wall of the support trough 40 to project at the level of the flange thereof and the flange of the food container 41.
Figure 8 also shows the support trough 11 which forms a housing both for the heating pouch, and for the food container 41.

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Figure 9 shows an embodimen-t of a self-heating container comprising a lid 42. Lid 42 is formed from two parts 43 and 44.
The lid 42 is fixed by small chimneys 45 which are fixed with the chamber 46 formed by the bottom 47 of the food trough 41 and the cover 39 or the chamber of the heating trough 30.

.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A self-heating receptacle comprising: a food vessel for food to be heated, and below said food vessel, a container sealed by a lid, said container containing two chemicals which are reagents in an exothermic reaction; a pouch within said container in which one of said chemicals is sealed from the other said chemical; and a flexible tearing filament for simultaneously opening said pouch and opening said container, thereby to permit said chemicals to contact each other and to take part in said exothermic reaction thereby to heat said food vessel, said tearing filament being connected to said pouch and being so arranged that, upon pulling said tearing filament, said tearing filament creates a line of tear across both said pouch and said lid.

2. A self-heating receptacle as claimed in claim 1, in which said pouch is suspended by its ends above the bottom of said container and is surrounded by said other chemical.

3. A self-heating receptacle as claimed in claim 2, in which said ends of said pouch are secured to upwardly facing ledges on said container.

4. A self-heating receptacle as claimed in claim 1, in combination with a housing in the bottom of which said container is disposed, said food vessel being disposed in said housing on top of said container.

5. A self-heating receptacle as claimed in claim 4, wherein said food vessel has a bottom that is spaced a short distance above the upper surface of said container.

6. A self-heating receptacle as claimed in claim 4, wherein said tearing filament extends across said lid below the bottom of said food vessel, and emerges from between said housing and said food vessel in a portion that can be grasped by the user to pull on the tearing filament, thereby to split both said pouch and said lid.

7. A self-heating receptacle as claimed in claim 1, wherein said flexible tearing filament terminates in a free end disposed in an outwardly opening recess in said container, and including a removable protective sheet closing said recess.

8. A self-heating receptacle as claimed in claim 1, in which the chemical in said pouch is water containing an anti-freeze additive.

9. The self-heating receptacle according to claim 8, wherein said anti-freeze additive is either methylated spirits or ethylene glycol.

10. The self-heating receptacle according to claim 1, including valve means coupled to said pouch for controlling the flow of water and the development of said exothermic reaction.

11. The self-heating receptacle according to claim 1, wherein said pouch is in the form of a pouch which comprises a central compartment containing water, and a peripheral compartment containing quicklime or calcium hydroxide.

12. The self-heating receptacle according to claim 1, including a support trough, said support trough containing said pouch at the bottom thereof, and said food vessel being disposed thereabove, with a cover of said support trough being arranged between said pouch and said food vessel.

13. The self-heating receptacle according to claim 12, including an empty space of 5 millimeters between said pouch and said food vessel, said empty space increasing the heating capacity of said self-heating receptacle.

14. The self-heating receptacle according to claim 12, wherein said lid is formed from two walls, and including fixing means allowing said lid to be fixed on said support trough, and allowing communication with the chamber formed by the bottom of said food pouch and the top of said pouch.

15. The self-heating receptacle according to claim 1, including means disposed about said two chemicals for preventing the formation of moisture during the thawing of said self-heating receptacle.

16. The self-heating receptacle according to claim 15, wherein the chemical for reaction is quicklime and wherein said quicklime is vacuum packed in a sealed envelope or in an antifreeze envelope or in an absorbing envelope so as to avoid dripping or thawing of frost which has been formed inside said pouch and which would prematurely set off the reaction of the quicklime during the period of thawing of the foods.