Patent Publication Number: US-2002000392-A1

Title: Tamper evident closure

Description:
[0001] The present invention relates to a tamper evident closure for a receptacle, and to a method of providing tamper evidence for a closed receptacle.  
       [0002] In our copending patent application Ser. No. PCT/GB99/04241 we describe a closure which can be utilised when it is required to package first and second materials such that they are separated initially, but are to be mixed at the point of use. Specifically, in our existing patent application, we describe a particularly effective closure for a self-heating or self-cooling beverage container.  
       [0003] The closure, described in PCT/GB99/04241 comprises a fluid container having means operable by pressing the base thereof to enable exit of fluid from the fluid container. This fluid exit causes the first and second materials to be mixed, and generates a heating or cooling effect, for example, where the package is a self-cooling or a self-heating beverage container.  
       [0004] The base of the fluid container of a closure as described above has been arranged to be stable in both of its states. Thus, the fact that the first and second materials in the package have been mixed is evident where the base of the closure is in its depressed condition. However, where the package is a self-heating container, for example, such that mixture of the first and second materials generates heat, and perhaps steam and/or causes the mixed materials to expand, it has been found that the base does not reliably remain in the depressed condition.  
       [0005] It is an object of the present invention to provide a more reliable tamper evident closure for a package such as a self-heating container.  
       [0006] According to a first aspect of the present invention there is provided in a package containing first and second separated materials, which materials are to be mixed at the point of use, and of which the first material is fluid, a method of providing evidence that mixture of the materials has occurred, the method comprising the steps of containing the first material in a fluid chamber, and causing mixture of the first and second materials by flowing the first material out of the fluid chamber, the method further comprising the step of arranging that flow of the first material out of the fluid chamber provides a visual indication that mixing has occurred.  
       [0007] The package and/or the fluid chamber may be made of, or incorporate, thermochromic materials such that any temperature changes effected by the exit of the first material from the fluid chamber cause colour changes in the package and/or the fluid chamber.  
       [0008] However, if the mixture of the first and second materials does not cause a temperature change, the thermochromic effect is not useful as a means to provide tamper evidence.  
       [0009] Preferably, the fluid chamber is, or has one or more areas which are, transparent and/or translucent whereby it can be determined visually if the fluid chamber contains the first material. Preferably, the first material is of a first colour and internal surfaces of the fluid chamber are of a second colour to aid in the determination of the presence of fluid in the fluid chamber.  
       [0010] Additionally and/or alternatively, exit of fluid from the fluid chamber is arranged to reveal patterns or designs within the fluid chamber which are externally visible, and/or to cause externally visible pattern or design changes.  
       [0011] The present invention also extends to a package arranged to provide evidence that mixture of materials has occurred therein in accordance with a method as defined above.  
       [0012] In a preferred embodiment, the fluid chamber, or part thereof, forms a closure for a package in the form of a self-cooling or a self-heating beverage container. In this embodiment, the fluid chamber contains a first chemical reactant, and the second chemical reactant is received within a receptacle formed by an external cavity of the beverage container.  
       [0013] A closure as defined above may have any of the features or combinations of features as set out in our copending patent application No. PCT/GB99/04241. Additionally and/or alternatively a closure as defined above may have any of the features or combinations of features as set out in our copending British patent No. 9926735.3. In this latter case, a cavity in a receptacle is divided by a membrane to form first and second separated chambers. A closure, for example, an end cap is used to seal the first chamber in which a fluid is contained. Piercing the membrane, for example, by depression of the closure causes mixture of the materials in the two chambers. Such an arrangement can also be rendered tamper evident as described above.  
       [0014] The invention also extends to a method of indicating when a closure for a receptacle has been tampered with, the receptacle comprising a first, fluid chamber in which a fluid is contained, a second, receiving chamber, and a closure of the receptacle which closes at least the fluid chamber, and the method comprising the steps of ensuring that attempts to open the closure, and hence the receptacle, cause the fluid to exit the fluid chamber and to enter the receiving chamber, and arranging that flow of the fluid out of the fluid chamber provides a visual indication that attempts have been made to open the closure.  
       [0015] A method of this aspect of the invention may incorporate any of the features defined above.  
       [0016] According to a further aspect of the present invention there is provided a tamper evident closure arranged to provide evidence that attempts have been made to open the closure.  
       [0017] The invention also extends to a tamper evident closure, said closure comprising or defining a fluid chamber in which fluid is contained, and operating means operable to enable exit of fluid from the fluid chamber, wherein the flow of fluid from the chamber is arranged to provide a visual indication that fluid has exited from the fluid chamber.  
       [0018] It may be sufficient to arrange the fluid chamber such that the presence of fluid therein is externally visible. Thus, when fluid has exited from the fluid chamber that will also be apparent by visual inspection.  
       [0019] However, it is presently preferred that the exit of fluid from the chamber provides a more positive visual indication.  
       [0020] In one embodiment, an internal surface of the fluid chamber is provided with a distinctive colour and/or patterns, the fluid is coloured and its colour differs from any colour on the internal surface of the fluid chamber, and the fluid chamber is, or has areas thereof, which are transparent or translucent such that the fluid chamber or the areas thereof have a particular appearance when the fluid is within the chamber. Exit of the fluid from the chamber then changes the visual appearance of the fluid chamber or of the areas thereof.  
       [0021] For example, if the internal surface of the fluid chamber has a first colour, and the fluid has a second colour, the fluid chamber when filled with fluid will have a third colour. When the fluid exits the chamber, its colour changes, and perhaps reverts to the first colour.  
       [0022] The invention has been described above with particular reference to packages for first and second materials, where the materials are to be mixed at the point of use. Although this is the presently preferred environment for a tamper evident closure of the invention as defined above the closure can be utilised to close any receptacle required.  
       [0023] Where the fluid exiting from the fluid chamber is not required to be mixed with contents of the receptacle, the closure may be provided with a receiving chamber for receiving fluid which has exited from the fluid chamber.  
       [0024] In an embodiment, the tamper evident closure is divided by a partition into a fluid chamber in which the fluid is contained, and a receiving chamber, wherein fluid exiting from the fluid chamber is received within the receiving chamber.  
       [0025] In an alternative embodiment, said closure is arranged to close a cavity whereby a fluid chamber is defined in which the fluid is contained, the closure further carrying piercing means for piercing a wall of the fluid chamber to cause fluid to exit therefrom. 
     
    
    
     [0026] Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which:  
     [0027]FIG. 1 shows, partly in section, a self-heating or a self-cooling beverage container illustrating an external reactant cavity thereof and a closure for the cavity,  
     [0028]FIG. 2 shows a larger view of the closure in its closed position,  
     [0029]FIG. 3 shows the closure of FIG. 2 after opening thereof,  
     [0030]FIG. 4 shows a section of a further embodiment of a tamper evident closure for a receptacle, and  
     [0031]FIG. 5 shows another example of a self-heating or a self-cooling beverage container incorporating a tamper evident arrangement of the invention. 
    
    
     [0032] The invention as shown in FIGS.  1  to  3  and  5  will be described with reference to a self-heating or a self-cooling beverage container. However, a tamper evident method of the invention, which is described below, finds general application wherever it is required to package first and second materials such that they are separated initially but are then mixed at the point of use. Generally, the first and second materials will be chemically reactive.  
     [0033] However, it should be noted that a tamper evident closure of the invention has universal application to receptacles, regardless of their contents, as will be described with reference to FIG. 4.  
     [0034] As described in PCT/GB99/04241, the beverage container shown in FIG. 1 is a metal or plastics material beverage container  10  having a substantially cylindrical peripheral wall  12  which is closed at one end by a top member  14 . A base member  16  of the container is indented to define an elongate external cavity  20  which extends within the peripheral wall  12 . 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. The external cavity  20  extends within this internal cavity  22 , but is separated therefrom by the wall of the base member  16 .  
     [0035] The external cavity  20  of the can  10  is utilised to contain a first reactant material. For a self-heating can the cavity may be filled with quicklime (calcium oxide). The cavity  20 , incorporating the quicklime, is closed by a closure  30 . For the self-heating can, for example, this closure  30  contains water.  
     [0036] 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  50  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 will retain the can in its inverted position until the exit of steam has been completed. At this stage the contents of the can will have been heated to a satisfactory temperature.  
     [0037]FIG. 2 shows the closure  30 . In the embodiment illustrated, the closure is moulded from plastics material and comprises a base member generally indicated as  32  and a lid generally indicated as  34 . At its centre, the base  32  has an upstanding plunger  44 . In the embodiment illustrated, this plunger  44  has an open top end for receiving a fixing  46  of the lid  34 .  
     [0038] The plunger  44  is affixed to the base centrally of a button  50  defined within the base  32  by an annular groove  48 . It will be seen that in the condition shown in FIG. 2, the button  50  is convex and is radially inwardly of the annular groove  48 .  
     [0039] When self-heating of the can  10  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, as indicated in FIG. 3, 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 plunger  44  in a direction to push the lid  34  out of the opening of the chamber  42 . Generally, it is expected that depression of the button  50  will cause a positive opening of the lid  34  of the chamber  42  whereby water is quickly released into the quicklime of the cavity  20  to commence the self-heating reaction. However, because the container  10  is inverted, it does not matter if positive and full opening of the lid does not occur. In this respect, as long as there is some opening of the lid, flow of the water from the chamber  42  will begin and this will, in itself, tend to ensure fuller opening of the lid.  
     [0040] Further details of the closure are described in PCT/GB99/04241.  
     [0041] Because the button  50  is stable in its depressed condition, it was thought that this would provide a visual indication when the closure had been operated to cause self-heating of the can. However, it has now been found that heating not only causes air and steam to be generated but also causes the quicklime to expand. These factors may cause the button  50  to be returned to its original stable condition.  
     [0042] Accordingly, to provide evidence that the closure has been operated to cause self-heating of the can, the internal surface of the lid  34  is coloured and/or provided with a bold pattern. The material of the base  32 , or at least a portion thereof, is transparent, and the water contained within the chamber  42  is coloured to obscure the colour or pattern on the internal surface of the lid  34  when this is viewed from externally of the closure by way of the base  32 . For example, the water might be coloured red and the internal surface of the lid  34  coloured blue. When the can, therefore, is in its initial full and unoperated state, visual inspection of the base of the can will reveal a red closure. After operation, as the water has exited from the chamber  42 , the closure will appear blue. The fact that the closure has been operated is therefore immediately visually apparent.  
     [0043] Rather than having the closure change colour, it would also be possible to have it change from transparent to opaque, or vice-versa. This could be achieved, for example by colouring the water to be opaque such that its exit from the closure reveals the internal surface of the lid  34 . Additionally and/or alternatively, the exit of the water could be arranged to cause a chemical reaction on internal surfaces of the closure.  
     [0044]FIG. 4 illustrates schematically a section through an embodiment of a tamper evident closure for a bottle, for example, for containing medicine. The tamper evident closure  100  illustrated in FIG. 4 has an internally threaded, cylindrical collar  102  enabling the closure to be screwed onto an externally threaded bottle neck (not shown). The closure  102  is child proof and thus, in known fashion, has to be squeezed radially or pushed downwardly as it is rotated to enable it to be unscrewed from the bottle neck.  
     [0045] As shown in FIG. 4, the closure  100  comprises a first, fluid chamber  104 , and a second, receiving chamber  106  divided by a partition  108  and arranged on top of the collar  102 . The fluid chamber  104  contains a coloured fluid which, in the initial condition of the closed and sealed medicine bottle, is visible through a window  110  in the top of the closure  100 .  
     [0046] The closure  100  is configured such that when an attempt is made to open the closure, for example, by squeezing the closure or pushing it downwardly, the fluid in the fluid chamber  104  is caused to flow into the receiving chamber  106 . For example, an attempt to open the closure might cause the partition  108  to be moved and/or pierced.  
     [0047] Where the partition  108  is pierced, the partition  108  can be used to conceal the fluid in the receiving chamber  106  so that it is not visible through the window  110 . By this means the closure  100  is seen to change colour whereby any tampering therewith is made evident.  
     [0048]FIG. 5 shows an alternative construction for a self-heating or a self-cooling beverage container with an alternative embodiment of tamper evident closure. In FIG. 5, features which are the same as or similar to those of the embodiment of FIGS.  1  to  3  have been accorded the same reference numerals.  
     [0049] As described above, the container  10  of FIG. 5 has an external cavity  20  which may be utilised to contain heating or cooling means. In this embodiment, the external cavity  20  is divided into a first chamber  132  and a second chamber  128  separated from the first by a breakable membrane  124 . The first chamber  132  is closed by a closure  130 .  
     [0050] When it is required to heat the contents of the can  10 , a button  50  of the closure  130  is pressed with the can inverted and stood on its top member  14 . The button thereby causes an elongate piercing member  142  to pierce the membrane  124  so that water from the first chamber  132  flows over quicklime within the second chamber  128  to cause the exothermic reaction.  
     [0051] It will be seen in FIG. 5 that the base member  16  is shaped to define at least one annular flange  134  in the wall of the external cavity  20 . This flange  134  is used to support the breakable membrane  124  whereby the external cavity  20  is divided into the first chamber  132  and the second chamber  128 .  
     [0052] Preferably, the breakable membrane  124  is a disc of metal foil bonded or otherwise sealed along its periphery to the annular flange  134  to define the two chambers  128 ,  132  and to keep their contents separated.  
     [0053] Substantially centrally thereof, the closure  130  carries the upstanding elongate piercing member  142 .  
     [0054] It will be appreciated that the closure  130  effectively seals the chamber  132  and prevents leakage of water which, in a self-heating can, may be received within the first chamber  132 . The membrane  124  hermetically seals the second chamber  128 , which may include a charge of quicklime whereby contamination of the quicklime is prevented.  
     [0055] When self-heating of the can is required, it is inverted and the button  50  is pressed. On depression, the button  50  moves from its initial convex domed position to a substantially concave domed position, and this moves the piercing member  142  in a direction to pierce or break the breakable membrane  124 . As a result, water is quickly released from the first chamber  132  into the quicklime within the chamber  128  to commence the self-heating reaction.  
     [0056] As previously described, the arrangement of FIG. 5 is such that there is a visual indication when the closure  130  has been operated. So, for example, the water within the first chamber  132  may be brightly coloured such that the view through the closure  130  changes colour once the water is released from the chamber  132 . The closure  130  is preferably clear or translucent so that such colour changes are readily apparent.  
     [0057] In one embodiment, the membrane  124  may be coloured and the piercing member  142  arranged to destroy a large area of the membrane  124  whereby the colour within the first chamber, as viewed through the closure  130 , changes.  
     [0058] As described above, any suitable means for making the exit of the fluid from the fluid chamber visually apparent can be employed.  
     [0059] It will be appreciated that modifications to or variations of the embodiments described and illustrated may be made within the scope of this application.