GB2173091A - A self-heating foodstuff container - Google Patents

Abstract

A self-heating foodstuff container is provided which is capable of generating heat by utilizing an exothermic reaction without supply of any material. It comprises a container body (10) for receiving the foodstuff, a heating unit (18) housed within the body and a cover member (28) secured to the heating unit for closing the same. The heating unit (18) includes a heat-conductive can (20) having a flange (22) for securing the can (20) to the body, an exothermic reaction agent (24) and a liquid containing bag (26) both disposed in the can. The bag (26) is positioned at a substantially central portion of the can (20) and is entirely surrounded by the reaction agent (24). The cover member (28) has an aperture (30) which permits a pin (16) or other sharp member to be inserted into the can (20) for rupture of the bag (26) to thereby cause the exothermic reaction within the can (20). <IMAGE>

Description

SPECIFICATION A self-heating foodstuff container The present invention relates to a foodstuffcontainerhaving incorporated therein heat generating means which is capable of warming the foodstuff such as coffee, soup, noodles and the like without supply of external heat energy.

It is known to warm the foodstuff by utilizing heat generated by a chemical exothermic reation such as hydration, oxidation or neutralization. A foodstuff container incorporating exothermic reaction agents is disclosed, for example, in the Japanese Utility Model Application as laid open under No.59-101882. The container disclosed therein has a compartment filled with an exothermic reaction agent ofthe type which causes a reaction when mixed with water, and when it is desired to generate heat, water is supplied into the container from an inletformed in an outerwall thereof. Thus, this container involves the practical inconvenience of carrying a water bottle, for example, in addition to the container.

This inconvenience can be removed by incorporat ing water or another reaction inducing liquid into the container. An attempt to utilize such a structure was carried out in orderto solve the problem of how to prevent mixture ofthe reaction agent with the liquid beforethe reaction was intended andhowto initiate the reaction promptly and efficiently when desired.

Further, during the exothermic reation the heated liquid must be prevented from leaking out of the container while expanded gas such as air should be expelled.

The exothermic reaction may be obtained by using metal oxide, which reaction requires no liquid.

However, metal oxide does not generate sufficent heat to warm the foodstuff to the desired temperature.

Accordingly, an object of the present invention is to provide a self-heating foodstuff container in which an exothermic reaction may be efficiently and promptly initiated without the necessity of carrying an external supply of liquid and in which an unintended reaction may be prevented from occurring.

Anobjectofatleasta preferredembodimentofthe present invention isto provide a self-heating foodstuff container in which an exothermic reaction agent incorporated therein may be utilized with maximal efficiency.

Afurtherobject of at least a preferred embodiment ofthe present invention is to provide a self-heating foodstuff container which permits gas expanded by an exothermic reaction to be expelled while preventing liquid from leaking out ofthe container.

According to the present invention, there is provided a self-heating foodstuff container comprising: a container bodyfor receiving afoodstuff a foodstufftherein and having an open end; a heating unit housed within said container body, said heating unit comprising a heat-conductive can, an exothermic reaction agent and a liquid containing bag both disposed in said can, said can having a flange defining an open end of said can and secured to said container body for closing said open end of said container body, and said bag being disposed at a substantially central portion of said can and being entirely surrounded by said reaction agent; and a cover member attached to said can for closing said open end thereof, said cover member having formed therein an aperture; whereby rupture of said bag through said aperture causes the exothermic reaction within said can to heat said foodstuff.

The reaction agent is preferably quick lime.

The heating unit may include fitted in the open end ofthe can a partition formed of a flexible material which sepa rates the cover memberfrom the reaction agent, the partition being formed with a slit ata position aligned with the aperture. Preferably, the heating unitfurther includes fitted in the open end of the can a ring memberfor supporting weights ofthe reaction agent and the bag to thereby maintain the bag in position.

The container may be equipped with a needle member which can be inserted into the can through the aperture for penetrating the bag.

Other &commat;r objects, features and advantages ofthe present invention will be apparent from thefollowing detailed description of preferred embodiments thereofwhen taken in conjunction with the accompanying drawings, in which: Figure lisa longitudinally sectioned view illustrating a self-heating foodstuff container according to a first embodiment ofthe present invention; Figure 2 is a cross sectional view taken along line ll-ll in Fig. 1; Figure 3 is an enlarged fragmentaryview illustrating a slightly modified part ofthe container in Fig. 1; Figure 4 is a longitundinally sectioned view showing a self-heating foodstuff container according to a second embodiment ofthe invention;; Figure 5 is a plan view of a cap used in the container in Figure 4; and Figure 6 is a diagram illustrating results of experiments conducted by the present inventors.

Referring now to Figs. 1 and 2 of the drawings, a self-heating container according to an embodiment of the present invention includes a cylindrical body 10 having open ends. The body 10may be formed of any suitable materials such as metal, paperboard or synthetic resin, and in this embodiment it has a multi-layer structure mainly comprising paper with its innermost layer being coated with synthetic resin to reduce conductivity of heat. The upper open end of the body 10 is closed by an upper cover 12 which is secured to the body 10 by a seam and which is provided with a conventional opening means such as a lift-up ring structure (not shown). Also secured to the upper end of body 10 in an easily detachable manner is a cap 14forholding a needle member 16.

A heating unit generally indicated by reference numeral 18 is housed within the body 10 and includes a cylindrical can 20 formed of heat conductive material such as aluminium or another metal. The can 20 is opened at its lower end and has a flange 22 which is secured to the lower end ofthe body 10 by a seam to thereby close the lower open end ofthe body 10. The heating unit 18furthercomprisesan exothermic reaction agent 24 and a liquid containing bag 26 both disposed in the can 20. The reaction agent 24 preferably comprises quick lime in the form of agglomerates of 2to 10 mesh,the quick lime being preferable in view ofcostand heat generating efficiency. The quick lime may be used either alone or in combination with a reaction control agent such as dolomite (CaMg(CO3)2).The bag 26 containing liquid, which is in this embodiment water, is positioned at a substantially central portion of the can 20 and is entirely surrounded bythe reaction agent 24, i.e. in this embodiment by the quick lime, hereinafter described in detail. The bag 26 is formed of relatively soft material such as synthetic resin so as to permitthe needle member 16 to penetrate the bag when it is desired to produce the exothermic reaction.

A lower cover 28 is provided to close the open end of the can 20 and is secured to the body 1 Otogetherwith the flange 22 of the can 20. Formed in the lower cover 28 is an aperture 30through which the needle member 16 can enterthe can 20. The aperture 30 is normally closed byan adhesive seal 32. The lower cover 28 is spaced from the reaction agent24 by means of an inner cover or partition 34 having a folded periphery of which the lower edge rests on the lower cover 28. The partition 34 is made of flexible, liquid-absorbent material such as pasteboard having a thickness of about 1.5mm.As is best shown in Figure 2, the partition 34 is provided with slits 36 crossing each other and aligned with the aperture of the cover 28, these slits being formed in such a manner as to preventthe reaction agent 24 from spilling butto permit the needle member 16to advancetherethrough.

The body 10 is filled with food or beverage 38 ofthe type which is suitable forconsuming in a heated condition. When the food or beverage 38 is to be consumed, the cap 14 is first removed from the body 10 and the needle member 16 is detached from the cap 14. Then the body 10 is placed upside down to insert the needle member 16 into the heating unit 18 through the aperture 30 of the lower cover 28. The seal 32 may be removed priorto the insertion ofthe needle member 16 or may be pierced by the member 16.

Passing through the partition 34 by spreading the slits 36, the sharp end of needle member 16 reaches the bag 26 to rupture the same. It is necessary atthis point to insertthe needle member 16 sufficentlyto penetrate the bag 26 so that holes are formed both in the lower surface and in the upper surface ofthe bag 26.

Immediatelyafterthe member 16 is drawn outofthe bag 26, the liquid contained therein spouts from the holeswherebya hydration reaction ofthe quick lime startsto generate heat. The generated heat is transmitted to the foodstuff 38 through the conductive can 20.

As described above, the bag 26 is located substantially atthe center portion ofthe can 20 and is entirely surrounded bythe reaction agent24. This location of the bag 26 is important in orderto permit an immediate diffusion ofthe liquid all overthe can 20 and thereby to provide a hydration reaction of maximum efficiency. Ifthe liquid container is located abovethe reactionagentorbelowtheagent,theagent tendsto preventthe liquid from being diffused to the opposite side ofthe can, producing a reaction only around the liquid container.Further, the non-reacted agent prevents heat from being conducted to the foodstuffsurrounding the can. Afterthe hydration reaction, the quick lime becomes powder which tends to close the holes of the liquid containerfrom which the liquid is to flow. Accordingly, a smooth and immediate diffusion ofthe liquid is particularly important when the reaction agent is quick lime. In a practical use, it is preferable to reverse the body 10 afterthe needle member 16 is drawn out so that the liquid may efficiently diffuse into the agent 24.

During the exothermic reaction, the partition 34 prevents the heated liquid from spouting outofthe can 20 while permitting expanded airto escape through the slits 36 to be expelled from the aperture 30. If desired, the lower cover 28 and the partition 34 may be formed with exhaust holes 40 and 42, respectively, as illustrated in Figure 3. The exhaust hole42 in the partition 34 has a diameter less than a diameter ofthe hole 40 in the cover 28. These holes are aligned with each otherto ensurethatthe expanded air is smoothly expelled from the container, thereby preventing the can 20 from being damaged by increased pressure.

Figure4illustratestheself-heating container according to a second embodiment of the invention, in which the same reference numerals are used to indicate the same or corresponding parts as in thefirst embodiment. In this second embodiment, a ring member 50 defining an opening 52 is disposed between the lower cover 28 and the partition 34 of disc-shape. The ring member 50 may be made of pasteboard having substantial thickness and is tightly fitted in the can 20 to supportthe weight ofthe reaction agent 24 and the liquid containing bag 26.

Formed in the lower cover 28 are exhaust holes 54 parts of which face the opening 52 ofthe ring member 50to allow the expanded airto escape in cooperation with the slits 36 ofthe partition 34. These exhaust holes, as well as the aperture 30, are normally closed by a seal 56 which is removed from the lower cover 28 beforethe insertion of needle member 16.

The cap 14 holding the needle member 16 is fitted overthe lowercover28 in a detachable manner.

Preferably, the cap 14 is retained in position during the exothermic reaction so as to conceal the lower cover 28 which is atthattime heated to a considerable temperature. In this case, plural recesses 58 are provided at periphery ofthe cap 14 as shown in Figure 5, through which expanded air escapes.

The ring member 50 is intended to secure the bag 26 in position within the reaction agent 24 even when the container is subjected to vibration. The inventors preparedtwenty samples ofthe containers according to the present invention, only half of which had the ring member 50. All samples were subjected to substantial vibration and thereafter exothermic reac tionwascausedto occur. The temperature ofthe foodstuff before and afterthe reaction was measured for each sample and the above experiment revealed the following. That is, the reaction raised the tempera- ture on an average 41.O"C in samples withoutthe ring member (A) and 41.5"C in samples having the ring member (B), the difference herein being small and not significant. However, irregularity in the maximum temperatures afterthe reaction was 3.8"C in samples (A) while the same was only 2.1"C in samples (B). This apparently meansthatthe ring member allows the required temperature to be obtained with less irregu laity.

Anotherexpenmentwas conducted by the inventors with respect to the diameter ofthe needle member 16 andthe resultsthereof are shown in Figure 6. It will be observed that if the needle member with a diameter of less than 2.0mm is used, the exothermic reaction takes a relatively long time and does not generate sufficient heat resulting in a maximum temperature of around 50C. This is due to the small amount of the liquid which spouts from the bag 26 at the initiation ofthe reaction. Also, when the diameter was increasedtoabout6.Omm, difficultywas encoun- tered in penetrating the bag 26 although a maximum temperature of a substantially acceptable level was obtained. On the other hand, when the needle memberof3.5mm diameterwas used, the exothermic reaction promptly generated sufficent heat and the needle memberwas smoothly inserted into the can 20 and penetrated the bag 26. Thus, a desired diameter of the needle memberwas found to be in the range of3 to4mm.

Claims (11)

1. A self-heating foodstuff container comprising a container body for receiving a foodstufftherein and having an open end; a heating unit housed within said container body, said heating unit comprising a heat-conductive can, an exothermic reaction agent and a liquid containing bag both disposed in said can, said can having a flange defining an open end ofsaid can and secu red to said container bodyforclosing said open end of said container body, and said bag being disposed at a substantially central portion of said can and being entirely surrounded by said reaction agent; and a cover member attached to said can for closing said open end thereof, said covermemberhavingformed therein an aperture; whereby rupture of said bag through said aperture causes the exothermic reaction within said can to heat said foodstuff.

2. A self-heating foodstuff container as claimed in claim 1, wherein said reaction agent is quick lime.

3. A self-heating foodstuff container as claimed in claim 1 or 2, wherein said heating unit includes fitted in said open end of said can a partition formed of a flexible material and separating said cover member from said reaction agent, said partition being formed with a slit at a position aligned with said aperture.

4. A self-heating foodstuff container as claimed in claim 3 wherein said slit comprises a pair of slits crossing each other.

5. A self-heating foodstuff container as claimed in claim 3 or4, wherein said cover member and said partition are formed with exhaust holes permitting expanded gas in said can to escape to the outside of the container during said exothermic reaction.

6. Aself-heatingfoodstuffcontainerasclaimed in any preceding claim, wherein said heating unitfurther includes fitted in said open end of said can a ring memberforsupporting the weight of said reaction agent and said bag to thereby maintain said bag in position.

7. A self-heating foodstuff container as claimed in any preceding claim,furthercomprising a needle member which can be inserted into said can through said aperture for penetrating said bag.

8. A self-heating foodstuff container as claimed in claim 7, wherein said needle member has a diameter of about 3 to at mm.

9. A self-heating foodstuff container as claimed in claim 7 or 8, wherein said needle member is secured to a cap fitted on one ofthe ends of said container body.

10. A self-heating foodstuff container as claimed in claim 9, wherein said cap is formed ata periphery thereof with recesses.

11. A self-heating foodstuff- container substantial- ly as herein described and as illustrated in the accompanying drawings.