There have been many proposas for self-heating or self-cooling beverage containers. WO 96/29255, for example, discloses a can having the same external dimensions and shape as conventional beverage cans, but having an indented base to define an external cavity in which means to cool or heat the contents of the can are received.

Heating or cooling of the contents of the can can be achieved by using two chemical reactants which are stable when separated, but which produce an exothermic reaction or an endothermic reaction when mixed. US patent No.

5,626,022 shows just one example, from many, of an insert for a self-heating or self-cooling can which enables mixing of the reactants when required. This construction, as is common, utilises a breakable or pierceable barrier to separate the two reactants and spikes or other piercing means to break the barrier when their reaction is required to heat or cool the can.

Increasingly, consumers will drink direct from a can rather than pouring out the contents. However, self-heating or self-cooling containers as shown, for example, in WO 96/29255 or in PCT/GB00/01865 are very effective at heating or cooling their contents, such that the can, particularly where it is made of metal, will be relative hot or cold. This can be unpleasant to drink from and can also be hazardous in that the temperature of the can can injure the lips.

There is also a potential danger with self-heating or self-cooling containers. The containers described in the International specifications referred to above are designed such that they effectively heat the contents of the can. It is, of course, possible for a consumer to start the heating process, for example, and then to open the can and dispense some of the contents. If this happens, or if the contents are dispensed before the heating process is initiated, overheating of the can with potentially hazardous effects can occur.

It is an object of the present invention to reduce the problems identified above.

According to the present invention there is provided a method of protecting a self-heating or a self-cooling container against premature opening, the container comprising a heating or cooling mechanism for heating or cooling contents of the container, and having opening means operable to enable access to the container contents, wherein a protective cover is arranged on the container so as to prevent operation of the opening means, and wherein the method comprises the step of enabling the removal of the protective cover only when the container and its contents have attained a predetermined temperature.

A method of an embodiment of the invention prevents premature opening of the container in that the protective cover cannot be removed before the heating or cooling mechanism has been operated, or before the container and its contents have attained the predetermined temperature. This obviates the problem of overheating arising because some or all of the contents have been dispensed before or during the heating process.

To make self-heating or self-cooling containers operate most effectively, it is generally necessary that the consumer wait until the heating or cooling mechanism has performed its function. Preferably, therefore, the predetermined temperature is chosen to be the steady state temperature to which the container and its contents are brought a predetermined time after the operation of the heating or cooling mechanism.

In one embodiment, the materials of the container and of the protective cover are arranged to react differently to changes in the temperatures to which they are subjected such that removal of the protective cover is enabled by the reactions of the container and of the protective cover to the predetermined temperature attained by the container and its contents.

For example, the container and the protective cover are arranged such that their relative sizes alter when they are subjected to changes in temperature. This change in relative sizes is used to enable removal of the

protective cover. Thus, where the protective cover is received within an area of the container, expansion of that container area relative to the cover will enable release of the protective cover. In an alternative construction, where the protective cover is arranged to engage around an area of the container, expansion of the cover will enable its release.

Additionally, and/or alternatively the protective cover is retained in position to prevent operation of the opening means by retaining means arranged to change state with changes in temperature.

For example, the retaining means may be a structural member joining the protective cover to the container and arranged to degrade or change state in some manner which enables at least part of the structural member to be broken as its temperature is changed. Where the container is heated, the structural member may melt or soften, and where the container is cooled, the structural member may become frangible In an embodiment of a self-heating container, the protective cover is arranged to expand upon heating relative to the container such that when the container and its contents have reached the predetermined temperature, the protective cover may be removed. For a self-cooling container, the protective cover may also be released by arranging for it to expand relative to the container. In this case, the protective cover would be arranged to contract less than the container upon cooling, for example.

Additionally and/or alternatively, the retaining means may be in the form of a glue, adhesive or other bonding material, for example, holding the protective cover on the container and arranged to degrade upon change of temperature whereby the hold or bond is released.

The present invention also extends to a self-heating or a self-cooling container having a heating or cooling mechanism for heating or cooling contents of the container, and opening means operable to enable access to the container contents, said container further comprising a protective cover arranged on the container so as to prevent operation of the opening means, the arrangement being such that the removal of the protective cover is enabled

only when the container and its contents have attained a predetermined temperature whereby the container is protected against premature opening.

According to a further aspect of the present invention, there is provided a self-heating or self-cooling container comprising a tubular peripheral wall within which first and second separated cavities extend, the first cavity receiving the contents of the container, and the second cavity housing a heating or cooling mechanism, a first end member closing the first cavity, and a second end member closing the second cavity, and opening means operable to enable access to the contents of the container formed in, or associated with, said first end member, said container further comprising a protective cover for protecting against premature opening of the container, said protective cover being arranged on the container so as to prevent operation of the opening means, the arrangement being such that removal of the protective cover is enabled only when the container and its contents have attained a predetermined temperature.

With a self-heating or self-cooling container of an embodiment of the invention, the protective cover is not removable until the container and its contents attain the predetermined temperature. As the protective cover prevents operation of the opening means until it has been removed, dispensing of the contents of the container before the operation of the heating or cooling mechanism, or during that process, is prevented.

Preferably, the materials of the container and of the protective cover are arranged to react differently to changes in the temperatures to which they are subjected such that removal of the protective cover is enabled by the reactions of the container and of the protective cover to the predetermined temperature attained by the container and its contents.

For example, the container and the protective cover are arranged such that their relative sizes alter when they are subjected to changes in temperature. This change in relative sizes is used to enable removal of the protective cover. Thus, where the protective cover is received within an area of the container, expansion of that container area relative to the cover will enable release of the protective cover. In an alternative construction, where the

protective cover is arranged to engage around an area of the container, expansion of the cover will enable its release.

Additionally, and/or alternatively the protective cover is retained in position to prevent operation of the opening means by retaining means arranged to change state with changes in temperature.

For example, the retaining means may be a structural member joining the protective cover to the container and arranged to degrade or change state in some manner which enables at least part of the structural member to be broken as its temperature is changed. Where the container is heated, the structural member may melt or soften, and where the container is cooled, the structural member may become frangible.

In an embodiment of a self-heating container, the protective cover is arranged to expand upon heating relative to the container such that when the container and its contents have reached the predetermined temperature, the protective cover may be removed. For a self-cooling container, the protective cover may also be released by arranging for it to expand relative to the container. In this case, the protective cover would be arranged to contract less than the container upon cooling, for example.

Additionally and/or alternatively, the retaining means may be in the form of a glue, adhesive or other bonding material, for example, holding the protective cover on the container and arranged to degrade upon change of temperature whereby the hold or bond is released.

A self-heating or a self-cooling container of an embodiment of the invention may incorporate any heating or cooling mechanism. Various arrangements are described, for example, in WO 96/29255. In a preferred embodiment, the heating or cooling mechanism comprises a first chemical reactant and a second chemical reactant received within the second cavity of the container. The chemical reactants are kept apart until heating or cooling of the contents of the container is required.

In one embodiment of a container of the invention, said opening means are formed in said first end member, and the protective cover is engaged over the opening means to prevent access thereto.

For example, the protective cover may be attached to the first end member to extend over the opening means and deny access thereto.

Alternatively, the protective cover may be a retaining device arranged to engage the opening means in a manner to prevent its operation. Where, for example, the opening means is a substantially traditional ring-pull, a retaining device may be a staple which is threaded through the user part of the ring-pull to prevent pivoting thereof relative to the first end member.

In an alternative embodiment, said opening means are formed in said first end member, and the protective cover is engaged on the container to enclose the first end member and thereby prevent access to the opening means.

Where the protective cover encloses the first end member, it is preferably reengageable on the container and provided with a drinking hole such that the contents of the container can be drunk through the protective cover. For example, the reengageable protective cover may be made of an insulating material such that the protective cover can act to protect the consumer from the temperature of the container. The cover also provides a more pleasant surface to drink from than the edge of a can, for example.

The protective cover may be of any appropriate shape. In one embodiment, the cover may be of the type increasingly supplied on beverage containers at takeaway outlets, for example, as described in US patent No.

4,589,569.

For hygienic reasons, the drinking hole in the protective cover may be closed by a breakable seal. The seal will be opened to reveal the drinking hole when the protective cover is reengaged on the container.

In an embodiment, the protective cover is shaped to provide a drinking rim within which the drinking hole is formed. Furthermore, a recess is provided in the protective cover adjacent the drinking hole.

In WO 96/29255, the second cavity of the container, which supports the heating or cooling mechanism, extends within the first cavity in which the container contents are received. It will be appreciated that the invention is not limited to any particular form or structure of self-heating or self-cooling container and is applicable, for example, to a container in which the second cavity surrounds the first cavity which houses the contents. Alternatively, the first and second cavities may extend side by side.

Although it is generally preferred that the end member for the first cavity is at the opposite end of the peripheral wall to that for the second cavity, this is not essential. The first and second end members may, if required, both be arranged at the same end of the peripheral wall.

A self-heating or self-cooling container of the invention may be used to contain any contents which may require cooling or heating. Thus, not only is the container suitable for beverages, it may alternatively be used for foodstuffs or medicines.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows, partly in section, a self-heating or a self-cooling container illustrating an external reactant cavity thereof and a closure for the cavity, Figure 2 shows a section through a protective cover to be provided on a top end member of a container of Figure 1, Figure 3 shows a top plan view of the cover of Figure 2, Figure 4 shows a plan view of a top end member of a container as in Figure 1, and Figure 5 shows schematically the use of a protective cover after opening of a container to aid drinking from the container.

The invention is described hereinafter with reference to a self-heating beverage container having a particular design of heating mechanism.

However, the invention is applicable to both self-heating and self-cooling containers and finds application irrespective of the proposed contents of the container. As described, the container has an external cavity in which heating or cooling means is received, the external cavity being closed by a closure.

The invention is not limited to such an arrangement and can be used with other constructions of self-heating or self-cooling mechanisms.

The container shown in Figure 1 may be a metal or plastics material beverage container 10 having a substantially cylindrical peripheral wall 12 which is closed at one end by a top end member 14. As described in WO 96/29255, a base end member 16 of the container is indented to define an elongate external cavity 20 which extends within the peripheral wall 12. It will be appreciated that the peripheral wall 12 and the top and base members 14 and 16 of the container together define an internal cavity 22 in which the beverage is received. It will be seen that the external cavity 20 extends within this internal cavity 22, but is separated therefrom by the wall of the base member 16.

The container 10 illustrated in Figure 1 is configured to have the same external dimensions and shape as a conventional beverage can. This means that the can can be filled and treated on existing filling lines. The can 10 may be made of aluminium, as is conventional, and have a ring-pull opening means 50 (Figure 4) in the top end member 14 as is also usual.

The external cavity 20 of the can 10 is to be utilised to contain a heating mechanism. In the embodiment shown, the heating mechanism comprises a first reactant material, which, for example, may be quicklime (calcium oxide).

The cavity 20, incorporating the quicklime, is closed by a closure 30. For the self-heating can this closure 30 may contain water.

When it is required to heat the contents of the can 10, the can is inverted and stood on its top member 14 so that the base of the closure 30 is accessible. A button on the bottom of the base is depressed whereby a water chamber 42 within the closure 30 is opened so that water from the closure 30

flows over the quicklime in the reactant cavity 20 to cause the exothermic reaction. The user retains the can in its inverted position until the contents of the can have been heated to a satisfactory temperature.

The size of the external cavity 20 and the amount of quicklime charged therein are chosen to ensure that the contents of the container can be heated within an appropriate time period of, for example, two to five minutes.

However, if the contents of the container were dispensed before or during operation of the heating mechanism there would be no contents to absorb the heat generated and excessive heating of the can would result. The invention proposes that such premature opening of the can be prevented and a protective cover to be fixed to the can to enclose the top end member 14 is shown in Figures 2 and 3.

As indicated above, the top end member 14 of the can 10 may be provided with opening means in the form of a ring-pull arrangement indicated generally at 50. The protective cover 52 shown in Figures 2 and 3 is attached to the can 10 such that it extends over the ring-pull 50 and fully encloses the top end member 14. Whilst the protective cover 52, therefore, is fixed onto the can 10, access to the ring-pull 50 is not possible.

The protective cover 52, as illustrated in Figures 2 and 3, has a top end member 54 from whose periphery a peripheral rim 56 depends. The top end member 54 is also configured to define an annular rim 58 in which a drinking hole 60 is defined. A recess 62 is provided adjacent the drinking hole 60.

The protective cover 52 may be made, for example, of a material which expands upon heating at a greater rate than the material of the can 10. For example, the protective cover may be made of an appropriate thermoplastics material. Accordingly, after the can 10 has been filled and sealed, the protective cover 52 may be applied thereto, whilst hot, to enclose the top end member 14. The cover 52 is then allowed to cool and shrink to contract onto the can. Additionally, and/or alternatively, the protective cover may be welded, bonded or glued in place by a heat meltable or heat softenable substance.

The self-heating can 10 with the protective cover 52 applied cannot be opened because the ring-pull 50 is not accessible. Opening is only possible by removal of the protective cover and this, in its turn, requires that the contents be properly heated by operation of the heating mechanism. When the container and its contents have been heated such that they attain the predetermined temperature, the cover 52 expands and/or the glue or other bonding material melts or softens to enable removal of the cover. The ring-pull 50 may then be operated to open the can whereby the contents can be dispensed.

The protective cover can be disposed of once it has been removed.

However, in the embodiment illustrated, the protective cover 52 has been designed to make drinking from the can safer and more pleasant. Accordingly the user may push the protective cover 52 to reengage it onto the can 10. The user can then drink the contents of the can through the drinking hole 60.

If required, the drinking hole 60 may be provided with a breakable seal or cover (not shown), which can be broken to reveal the drinking hole when the contents are to be drunk from the can. This mechanism keeps contaminants from entering through the drinking hole into the cover whilst this is fixed on the can initially.

Figure 5 shows the reengagement of a protective cover, as 52, onto a can 10 and shows the use of the cover 52 when drinking from the can 10. In the embodiment of the cover 52 shown in Figure 5, a further depending rim 64 extends the first depending rim 56. Such an additional rim 64 could be used, if required, as the means to retain the protective cover 52 on the can either through contraction and expansion and/or by being bonded or otherwise joined to the can.

In the embodiments described so far, it has been assumed that the can 10 is a substantially conventional can with a ring-pull. Of course, other opening and closing means might be utilised. For example, the top end member, as 14, may be engaged on the container by screw threads or other means at its periphery. In that case, the protective cover may be in the form of an annular rim engaged around the peripheral edge of the container 10. This annular rim

would be removable, as described above, in response to heating of the container to enable opening of the container. The annular rim would be reengageable to provide an insulating rim for drinking from the container as described above.

It will be appreciated that other variations or modifications to the embodiments as described and illustrated may be made within the scope of the appended claims.