SELF-HEATING OR SELF-COOLING CONTAINERS

Abstract: A self-heating metal can (10) has an indented base (16) defining an external cavity (20) which is utilised to contain heating means. The heating means comprises quicklime (26) filled within a first chamber (28) and water within a second chamber (32) of the cavity (20). A breakable membrane (24) separates the two chambers (28, 32) and the second chamber (32) is closed by closure (30). Depression of a button (50) of the closure moves an elongate piercing member (42) to pierce the membrane (24) so that water from the chamber (32) flows over the quicklime (22) to cause the exothermic reaction.

Description: SELF-HEATING OR SELF-COOLING CONTAINERS The present invention relates to a self-heating or a self-cooling container. There have been many proposals 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, proposes the use of a module, which is pre-assembled and is then inserted into the can. Many examples of such inserts and modules have been proposed, but none of them have been found to be entirely satisfactory. The designs are often overly complicated, or do not withstand normal transport and handling, or are prone to failure. Furthermore, the need to form the module as a sub- assembly adds to the manufacturing costs. The present invention seeks to overcome the problems noted with the existing inserts for self-cooling and self-heating containers. According to the present invention there is provided a self-heating or self-cooling container having a tubular peripheral wall, a top member closing one end of the peripheral wall, and a base member closing the other end of the peripheral wall, an internal cavity for the contents of the container being defined within the peripheral wall, wherein the base member is indented to define an external cavity which extends within the peripheral wall but is separated from the internal cavity, and wherein means for heating or cooling the contents of the container are received within said external cavity, said heating or cooling means comprising a breakable membrane dividing the external cavity into first and second chambers, a first reactant material sealed within the first chamber by said breakable membrane, a closure member closing said second chamber to retain a second reactant material therein, and piercing means movable to break or pierce the breakable membrane whereby said first and second reactant materials can mix. With an embodiment of a self-heating or a self-cooling container of the invention, there is no requirement to form the heating or cooling means into a sub-assembly. Instead, the individual components of the heating or cooling means are simply assembled within the external cavity of the container. This preferably occurs after the container has been filled, and its contents have been subjected to any required treatments. When the reactant materials mix there will generally be a chemical reaction, for example, to produce a heating or a cooling effect. Such a chemical reaction may be associated with pressure changes, as well as temperature changes. Accordingly, pressure venting means are preferably associated with the closure member and/or with the container. In a preferred embodiment, a one way valve or seal is associated with the closure. Although the container was developed specifically for use with self- cooling or self-heating beverage containers, it is adaptable for use as a container in which a first material which it is required to mix with a second material can be contained and subsequently mixed. The first and second materials, which are required to be mixed at the point of use, may be chemically reactive. The present invention extends to a container for facilitating the mixing of first and second materials, the container comprising a cavity, a breakable membrane dividing the cavity into first and second chambers, a first material sealed within the first chamber by said breakable membrane, a closure member closing said second chamber to retain a second material therein, and piercing means movable to break or pierce the breakable membrane whereby said first and second materials can mix. For example, hair dyes and hair perming agents are required to be rendered active at the point of their application to hair. This is done by reacting a first chemical with the rest of the formulation. The first chemical may be housed in the second chamber of a container of the invention, and the first chamber in the cavity used to contain the rest of the formulation. The closure is pressed when it is required to use the hair dye or hair perming agent to enable mixing of the first chemical with the rest of the formulation. In a totally different sphere, a container of the invention may constitute a paint can, for example, with paint of one colour, contained in the first chamber, to be mixed with paint of another colour kept in the second chamber. By this means, for example, a container of the invention would allow a paint comprising a selected mix of two colours to be made available. A container of the invention is primarily suitable to contain fluids, but may be utilised in any situation where the mixing of a fluid material with other materials, and/or a chemical reaction is required at the point of use. It would be possible, for example, for the closure member and the piercing means to be separate elements. For example, a piercing member could be arranged to be movable through and with respect to the closure member. However, in a presently preferred embodiment, which is simple to construct and easy to use, the closure member supports the piercing means and enables movement of the piercing means to break or pierce the breakable membrane. It would also be possible for the closure member to comprise a cap in which a compartment is defined which may receive the second reactant material and/or enclose further elements of the container. However, it is presently preferred that the construction be as simple as possible. In an embodiment, the closure member comprises a periphery arranged to engage the container, and carries at least one elongate piercing member which extends from the inner surface of the closure member. The or each elongate piercing member may be fixed to the inner surface of the closure member or may be integrally formed therewith. It is necessary for the piercing member(s) to be movable to pierce the breakable membrane. Such movement could be accommodated by mounting the piercing member(s) on a pushbutton or plunger construction supported within the closure member. Where the piercing member(s) are directly affixed to, or integrally formed with, the closure member, hinge means may be formed in the closure member. In a presently preferred embodiment, the closure member and the piercing member(s) are formed from a plastics material, and the closure member is formed to provide the necessary movement for the piercing member(s). In a preferred embodiment, an elongate piercing member is affixed to the closure member and upstanding therefrom, the arrangement being such that depression of the closure member adjacent the piercing member moves the member to pierce the breakable membrane. Preferably, the piercing member is arranged substantially centrally of the closure member. The piercing member may be affixed to the closure member. In a preferred embodiment, the elongate member is integrally formed with the closure member. In a preferred embodiment, the piercing member is mounted on the closure member by way of a button formed in the closure member. This button may be a separate structure provided in the closure member. Preferably, however, the button is moulded integrally with the closure member. In a preferred embodiment, the button is defined by an annular groove and has a domed shape. Normally, the dome is convex, but pressure thereon causes a overcentre movement reversing the curvature of the dome. This pushes the piercing member carried thereby towards the breakable membrane to pierce the breakable membrane. Preferably, the closure member is arranged to clip onto the base of the container such that it acts to close its external cavity. Alternatively, the closure member may be mechanically connected to the container by other means, for example, by a screw connection. For example, the closure member may be provided with a peripheral rim which is appropriately shaped to clip onto the base of the container. Although the closure member may be of any required peripheral shape, in a preferred embodiment the closure member is circular, and, in this case, its peripheral rim is annular. An annular groove may be defined in the closure member, radially inwardly of the peripheral rim, and arranged to receive a base edge of the container. Preferably, the closure member and its peripheral rim are shaped such that any increase in pressure within the second chamber of the external cavity tends to urge the rim into better engagement with the base edge of the container. A container of the present invention was developed specifically for use as a self-cooling or self-heating container for beverages. Of course, it will be appreciated that the container may be used for any contents. The reactant materials are chosen to give the reaction required and may be in any particular form. However, the structure of the cooling or heating means is particularly appropriate where the first reactant material sealed within the first chamber is in a powder, granular, or other particulate form, whilst the second reactant material in the second chamber is a fluid. When it is required to cool or heat the container, it is inverted to provide access to the base of the closure member which is then pressed to cause the piercing member to pierce the breakable membrane. This releases the fluid in the second chamber such that it flows into the first chamber to begin the chemical reaction. The use of a second reactant material in fluid form assists in the mixing process. For a self-heating container, for example, quicklime may be filled within the first chamber and water retained within the second chamber. Lime is extremely hydroscopic and it has been found that sealing the lime by the breakable membrane within the first chamber improves the shelf life of the container greatly as the lime is thereby sealed from contamination. The breakable membrane may be of any material capable of sealing the first reactant material in the first chamber, and supporting the weight of that material when the container is in its normal upright position. For example, the breakable membrane may be formed by a disc of a metal foil secured to the external cavity to extend across it. In a presently preferred embodiment, the external cavity is shaped to define an annular flange therein. A disc shaped breakable membrane may then be affixed to the annular flange after a charge of the first reactant material has been filled into the first chamber. For example, the disc shaped breakable membrane may be affixed to the annular flange by way of a carrier member. Alternatively, the periphery of the disc shaped breakable membrane may be affixed directly to the annular flange. Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows schematically one embodiment of a self-heating beverage container, Figure 2 shows an enlarged view of the base of the container of Figure 1 in the inverted position, Figure 3 shows an example of a container of the invention, in the inverted position, and illustrates, the shape of its external cavity and of its closure member, and Figure 4 shows an inverted container having a carrier for the breakable membrane. The invention will be described hereinafter specifically with reference to a self-heating beverage container. However, the container of the invention, which is described below, may alternatively be arranged to be self-cooling. In fact, and as set out above, the container finds general application whenever it is required to package goods in a manner requiring two materials to be mixed at the point of use. The container shown in Figure 1 may be a metal or plastics material container 10 having a substantially cylindrical peripheral wall 12 which is closed at one end by a top member 14. As described in WO 96/29255, a base 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 contents, such as a beverage, are 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 10 can be filled and treated on existing filling lines. The external cavity 20 of the can 10 is to be utilised to contain heating or cooling means. Where the can 10 is a self-heating can, for example, the heating means may comprise quicklime (calcium oxide) 26 filled within a first chamber within the cavity 20. A second chamber 32 within the cavity 20, separated from the first by breakable membrane 24, is filled with water. The second chamber 32 is closed by closure 30. 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, described below, on the bottom of the base is depressed whereby an elongate piercing member 42 pierces the membrane 24 so that water from the chamber 32 flows over the quicklime 22 to cause the exothermic reaction. The steam which is generated is allowed to vent around the periphery of the closure 30 through vents or recesses (not illustrated) formed in either the periphery of the closure 30 or in the wall of the cavity 20 or in both. The user will retain the can in its inverted position until the exit of steam has been compleied. At this stage the contents of the can will have been heated to a satisfactory temperature. The structure of the heating means is apparent from Figures 2 and 3. As can be seen in Figure 3, the base member 16 is shaped to define at least one annular flange 34 in the wall of the external cavity 20. This flange 34 is used to support the breakable membrane 24 whereby the external cavity 20 is divided into a first chamber 28 and a second chamber 32. It will be appreciated that the breakable membrane 24 may be piercable, rupturable or breakable in other manner. In a preferred embodiment, the breakable membrane 24 is a disc of metal foil. After the first reactant material, for example, the quicklime 26 (not shown in Figure 3) has been charged into the first chamber 28, the membrane 24 is positioned in the cavity 20 and bonded or otherwise sealed along its periphery to the annular flange 34. Preferably, and as shown in Figures 2 and 3, the closure 30 is formed from plastics material and is integral with the elongate piercing member 42. The closure 30 comprises a substantially circular member having an annular peripheral rim 36. This rim 36 defines an annular recess 38 which enables the closure 30 to be clipped on to the base of the can 10. It will be seen that in the embodiment illustrated, the free edge of the rim 36 carries an annular projection 40 which is arranged to engage within an annular groove provided externally of the base edge of the can 10. For security of the connection, the peripheral area of the closure 30 is made to have a greater thickness of material than the central area thereof. Substantially centrally thereof, the closure 30 carries an upstanding elongate piercing member 42. In the embodimenr illustrated, this piercing member 42 is cylindrical and has a sharpened free end. However, it would alternatively be possible to provide a number of individual elongate piercing members for example, in the form of spikes or barbs, which are arranged along the circumference of a circle or in some other appropriate configuration. The piercing member 42 is fixed to the closure 30 centrally of a button 50 defined within the closure 30 by an annular groove 48. It will be seen that in the condition shown in Figures 2 and 3, the button 50 is convex and is positioned radially inwardly of the annular groove 48. It will be appreciated that after the quicklime 26 is sealed within the first chamber 28 by the breakable membrane 24, an open second chamber 32 is thereby defined. This chamber 32 is then filled with water which is retained therein by snap fitting the closure 30 into position on the base of the can 10. In this respect, it is important to ensure that the chamber 32 is substantially water tight and, in the embodiment shown in Figure 3, the periphery of the closure 30 is shown to have an integrally formed seal in the form of an annually extending wiper 52. It is additionally or alternatively possible to incorporate within the peripheral region of the closure 30 a one way valve or seal 56 (Figure 1 ) arranged to prevent the ingress of air from the outside. Such an atmospheric valve is effective to seal water within the chamber 32 but enables venting of the chamber. By such measures, it can be ensured that the closure 30 effectively seals the chamber 32 and prevents leakage of water therefrom during normal transport and handling. Furthermore, the membrane 24 hermetically seals the chamber 28 with its charge of quicklime whereby contamination of the quicklime is prevented. This increases the shelf life of the heating means of the can 10. When self-heating of the can is required, it is inverted as described above. The button 50 is pressed. The button 50 is arranged to have an overcentre action such that on depression, the button moves from its initial convex domed position to a substantially concave domed position. Preferably, the button is stable in both of its states. This movement of the button 50 moves the piercing member 42 in a direction to pierce or break the breakable membrane 24. Generally, it is expected that depression of the button 50 will cause a positive break in the membrane 24 whereby water is quickly released into th^ quicklime within the chamber 28 to commence the self-heating reaction. However, because the can 10 is inverted, it does not matter if there is some failure in the break provided as long as some rupture of the membrane 24 occurs. In this respect, with any rupture in the membrane 24, a flow of water from the chamber 32 into the chamber 28 will occur and this, in itself, will tend to ensure that a larger rupture in the membrane 24 is caused. The reaction which takes place between the water and the quicklime will generate steam and it is necessary to ensure that air and steam can exit from the external cavity 20. In the embodiment illustrated, vent channels 54, which are visible in Figure 2, are provided through the material of the periphery of the closure 30. It will be seen that the channels 54 open into the external cavity 20 radially outwardly of the wiper 52. The wiper 52 is thereby able to prevent egress of water whilst allowing air and steam to exit. The self-heating container described and illustrated can be filled on conventional filling lines, and the contents thereof may be subjected to any treatment required. For example, contents of the container may be pasteurised and/or sterilised. Thereafter, it is a simple matter to invert each completed and filled container and provide it with heating means in its external cavity 20. Thus, the external cavity 20 is charged with a predetermined amount of quicklime, a breakable membrane 24 is inserted and is bonded or otherwise fixed by appropriate means to the annular flange 34, a charge of water is then filled into the thus defined second chamber 32, and the closure 30 is clipped onto the container 10. The embodiment described above shows a particularly simple construction for the heating means and a similar construction can be used for cooling means. The final can is sufficiently robust to withstand normal transport and handling. It is preferred that the closure 30 be made of a plastics material. Presently it is preferred that the plastics material be translucent or transparent. When the container 10 is a metal can there can be difficulties if it is required, for example, to affix the breakable membrane 24 to the annular flange 34 using a meltable adhesive. For example, a flange, as 34, formed on a metal can wi not be as smooth as that on a plastics material can. Furthermore, the metal can acts as a heat sink which takes away heat from the adhesive. As a result it can be difficult to obtain a perfect seal between the periphery of the membrane 24 and the flange 34. Figure 4 shows an embodiment of the present invention able to reduce difficulties of this nature. As illustrated, in the embodiment of Figure 4, the breakable membrane 24 has been secured to a carrier 60. Preferably this carrier 60 is integrally formed of plastics material and has a cylindrical plug 62 having an annular ring 64 at one end thereof. A peripheral area of the breakable membrane 24 is adhered, bonded or otherwise fixed to the annular ring 64 such that it is stretched across the carrier. The carrier 60 is then assembled with the annular flange 34 such that it plugs the chamber 28 and the membrane 24 hermetically seals the chamber 28. It will generally be necessary to fix the carrier 60 in its position to ensure that the chamber 28 is, and remains, hermetically sealed by the breakable membrane 24. For example, the annular ring 64 may be adhered or otherwise fixed to the annular flange 34. Where the carrier 60 is of plastics material and the breakable membrane 24 is a foil disc, it is generally straightforward to achieve a perfect seal between the two by gluing, for example. It is then only necessary to ensure that the carrier 60 reliably plugs the chamber 28. The carrier 60 may be of a solid body of plastics material. Alternatively, constructions are possible where the carrier 60 is of semi permeable material, for example, or is in the form of a sieve. It is proposed that external surfaces of the closure and/or of the container 10 be made of, or coated with, materials having thermochromic properties. In this way, if the closure has been operated to cause self-heating of the can at any time, this is immediately apparent by, for example, a change in the colour of part of the closure and/or of part of the container 10. It will be appreciated that modifications to or variations of the embodiments described and illustrated may be made within the scope of this application.

Claims: CLAIMS 1. A self-heating or self-cooling container having a tubular peripheral wall, a top member closing one end of the peripheral wail, and a base member closing the other end of the peripheral wall, an internal cavity for the contents of the container being defined within the peripheral wall, wherein the base member is indented to define an external cavity which extends within the peripheral wall but is separated from the internal cavity, and wherein means for heating or cooling the contents of the container are received within said external cavity, said heating or cooling means comprising a breakable membrane dividing the external cavity into first and second chambers, a first reactant material sealed within the first chamber by said breakable membrane, a closure member closing said second chamber to retain a second reactant material therein, and piercing means movable to break or pierce the breakable membrane whereby said first and second reactant materials can mix. 2. A self-heating or self-cooling container as claimed in Claim 1 , further comprising pressure venting means associated with the closure member and/or with the container. 3. A self-heating or self-cooling container as claimed in Claim 2, wherein a one way valve or seal is associated with the closure. 4. A container for facilitating the mixing of first and second materials, the container comprising a cavity, a breakable membrane dividing the cavity into first and second chambers, a first material sealed within the first chamber by said breakable membrane, a closure member closing said second chamber to retain a second material therein, and piercing means movable to break or pierce the breakable membrane whereby said first and second materials can mix. 5. A container as claimed in any preceding claim, wherein the closure member supports the piercing means and enables movement of the piercing means to break or pierce the breakable membrane. 6. A container as claimed in Claim 5, wherein the closure member comprises a periphery arranged to engage the container, and carries at least one elongate piercing member which extends from the inner surface of the closure member. 7. A container as claimed in Claim 6, wherein the or each elongate piercing member is fixed to the inner surface of the closure member, or is integrally formed therewith. 8. A container as claimed in any of Claims 5 to 7, wherein elongate piercing member(s) are mounted on a pushbutton or plunger construction supported within the closure member. 9. A container as claimed in Claim 7, further comprising hinge means formed in the closure member to enable movement of the piercing member(s) to pierce the breakable membrane. 10. A container as claimed in Claim 6, wherein the closure member and the piercing member(s) are formed from a plastics material, and the closure member is formed to provide the necessary movement for the piercing member(s). 11. A container as claimed in Claim 10, wherein an elongate piercing member is affixed to the closure member and upstanding therefrom, the arrangement being such that depression of the closure member adjacent the piercing member moves the member to pierce the breakable membrane. 12. A container as claimed in Claim 11 , wherein the piercing member is arranged substantially centrally of the closure member. 13. A container as claimed in Claim 11 or Claim 12, wherein the elongate piercing member is integrally formed with the closure member. 14. A container as claimed in any of Claims 10 to 13, wherein the piercing member is mounted on the closure member by way of a button formed in the closure member, and wherein the button is moulded integrally with the closure member. 15. A container as claimed in Claim 14, wherein the button is defined by an annular groove and has a domed shape. 16. A container as claimed in any preceding claim, wherein the closure member is arranged to clip onto the base of the container such that it acts to close its external cavity. 17. A container as claimed in Claim 16, wherein the closure member is provided with a peripheral rim which is appropriately shaped to clip onto the base of the container. 18. A container as claimed in Claim 17, wherein the closure member is circular, and its peripheral rim is annular, and wherein an annular groove is defined in the closure member, radially inwardly of the peripheral rim, and arranged to receive a base edge of the container. 19. A container as claimed in Claim 17 or Claim 18, wherein the closure member and its peripheral rim are shaped such that any increase in pressure within the second chamber of the external cavity tends to urge the rim into better engagement with the base edge of the container. 20. A container as claimed in any preceding claim, wherein the first reactant material sealed within the first chamber is in a powder, granular, or other particulate form, and the second reactant material in the second chamber is a fluid. 21. A container as claimed in any preceding claim, wherein the breakable membrane is of any material capable of sealing the first reactant material in the first chamber, and supporting the weight of that material when the container is in its normal upright position. 22. A container as claimed in Claim 21 , wherein the breakable membrane is formed by a disc of a metal foil secured to the external cavity to extend across it. 23. A container as claimed in Claim 21 or Claim 22, wherein the external cavity is shaped to define an annular flange therein and wherein a disc shaped breakable membrane is then affixed to the annular flange after a charge of the first reactant material has been filled into the first chamber. 24. A container as claimed in Claim 23, wherein the disc shaped breakable membrane is affixed to the annular flange by way of a carrier member. 25. A container as claimed in Claim 23, wherein the periphery of the disc shaped breakable membrane is affixed directly to the annular flange. 26. A self-heating or self-cooling container substantially as hereinbefore described with reference to the accompanying drawings. 27. A container substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: SEARLE MATTHEW JOHN, SEARLE, MATTHEW, JOHN
Applicants: SEARLE MATTHEW JOHN, THERMOTIC DEV LTD, SEARLE, MATTHEW, JOHN, THERMOTIC DEVELOPMENTS LIMITED
Application year: 2000
Main classification: A47J36
IPC codes: A47J36, B65D81, F25B23, F25D5