This invention relates to an insert for a drink container and, in

4 particular, to an insert to be put in a drink container which is under

-- pressure in order that, when the container is opened, material is released from the insert into the drink in the container so as to modify the nature of that drink.

Inserts of a variety of types have been proposed for inclusion in drink containers, in particular for use with drink containers which contain beer under pressure. The object of these inserts is to release gas into the beer when the drink container is opened and thereby to cause the formation of an enhanced "creamy" head on the beer. Known inserts have not been entirely satisfactory and are of limited applicability.

In a known type of insert the insert comprises a vessel having a hollow part, closed at one end and open at the other, and, slidably and sealingly engaged with the open end, a plunger part and valve means permitting only under certain relative pressure conditions inside and outside the vessel egress of material from the vessel or egress of material into the vessel.

The disadvantage with this type of insert are that the tolerances required for a good clean hermetically sealed operation, with the slidably operation of the device, are so tight that the inserts are costly and difficult to produce.

Further, the inserts are also liable to jamming in operation.

The present invention is concerned with providing an insert for use in a drink container in which the above disadvantages are alleviated if not fully overcome.

In accordance with the present invention there is provided an insert for inclusion, and use, in a drink container, which insert includes:

- a base section;

- a top section-,

- a thin wall section which separates the base section and the top section and which acts with the base section and top section to define a space which is hermetically sealed from the surrounding ambient atmosphere in the drink container; and

- means to destroy the hermetic seal separating the space from the surrounding atmosphere within the drink container when particular conditions are experienced; wherein the insert is inserted, or assembled, in a drink container free from drink such that the space is at substantially ambient pressure, and upon the filling of the drink container with drink, and any further treatments including sealing of the drink container, the contents of the drink container are caused to be in a pressurised state and the thin wall section of the insert collapses, or partially collapses, causing the pressure in the space to equilibriate with the surrounding atmosphere pressure, and the insert is provided with means to hold the insert in the collapsed position, whereupon releasing the pressure in the drink container the hermetic seal is destroyed causing the material in the space to be released into the drink in the drink container.

The present invention has the advantage over those previously described in that the insert relies on well proven and cost effective manufacturing techniques. Further, as no mutually moving components are involved there are no chances of the insert jamming.

In a particular arrangement of the present invention the insert comprises a substantially rigid frame having a number of collapsible convex surface which collapse inwardly on application of a pressure across them.

According to a further aspect of the invention of independent significance an insert for a drink container comprises a base section and a top section defining a space which is hermetically sealed from its surroundings; and valve means for destroying the hermetic seal; in which the based and/or top include at least a part which is deformable; in which the insert is inserted or assembled at substantially ambient pressure and subsequent pressurisation of the container causes the deformable part or parts to collapse until the space within the insert equilibriates with the pressure within the container; and in which the insert is held in the collapsed position and the release of the pressure within the container causes the valve means to open and break the hermetic seal, causing the contents of the insert to be released into the container.

Alternatively, according to another aspect of the invention an insert for a drink container comprises at least one section defining a space which is hermetically sealed from its surroundings; and valve means for destroying the hermetic seal; in which one or more of the sections includes at least a part which is deformable; in which the insert is inserted or assembled at substantially ambient pressure and subsequent pressurisation of the container causes the deformable part of parts to collapse until the space within the insert equilibriates with the pressure inside the container; in which the insert is formed from a material of which the actual resilience causes the insert to be held in the collapsed position; and in which the release of the pressure within the container causes the value means to open and break the hermetic seal, causing the contents of the insert to be released into the container.

The base section may be seam welded to the top section, or may be co-formed with the top section by blow moulding a one-piece insert.

In one embodiment of the present invention the insert is formed from a thermoplastically behaving polymeric material, and most preferably, polypropylene.

Preferably the insert is formed from a suitable metal material, for example aluminium or mild steel. Furthermore it is preferable to use a laminate of metal and polymeric material in order to prevent direct contact between metal and the contents of the drink container. It is a further advantage that use of a metal/polymer laminate avoids the need for a non-oxiding gas within the insert.

As will be well appreciated by those skilled in the art, the insert needs to be formed with dimensions that will enable it to collapse in a controlled fashion under the pressures which will normally be experienced in a drink container during the canning operation, i.e. between 30 and 90 psi. However, it will also be appreciated that the insert needs to be designed to operate under the conditions which will be experienced in a particular system.

Now in an embodiment where the insert is formed from polypropylene the thin walled section, preferably, has a thickness in the region of 0.3 to 0.45 mm, and most preferably in the order of 0.35 mm.

In an embodiment where the insert is formed from aluminium the thin walled section, preferably, has a thickness in the region of .09 mm to 0.2 mm, and most preferably, 0.12 mm.

If the insert is formed from mild steel the thin walled section, preferably, has a thickness in the region of 0.12 mm to 0.18 mm, and, most preferably in the order of 0.15 mm.

In the circumstances where the insert is formed from a metallic material the actual resilience of the metallic material can act to provide the means to hold the insert in a collapsed position. Alternatively, the resilience of the metallic material can be used to provide assistance in holding the insert in a collapsed position and a second means to hold the insert in a collapse position will be provided.

In a particular arrangement of the present invention the means to hold the insert in the collapse position comprises a number of posts which are fixedly secured to the insert so that they are stable in space during collapse of the insert and which posts pass through holes as the insert collapses, with the post carrying detent means which pass through the holes in one direction only and so act to prevent the insert re-establishing itself when the pressure in the drink container is relieved.

In an alternative arrangement the means to hold the insert in a collapsed position comprises a shell member having a collar, which shell member moves in space as the insert collapses so that the collar acts against a number of posts which are fixedly secured to the insert so that they are fixed in space as the insert collapses and which post carry detent means so that as the insert collapses the post moves through holes provided in the insert and the detents act to lock the insert in position and prevent the insert from re-establishing itself.

Further, the posts provided with the above arrangements can be caused to move outwardly so that they engage the walls of a drink container and act to stabilise the insert within the drink container.

Normally, the insert will be provided with means which act to stabilise the insert in the drink container. By this it is meant the insert will be held in a position in the drink container relative to the walls of the drink container and, therefore, it will not be able to move around and rattle in the drink container.

The means which act to stabilise the insert in the drink container may be any one of those used with the presently known forms of inserts for use with drink containers, for example, the insert could form an interference fit with the walls of the drink container

Alternatively the means to stabilise the insert in the container may be provided by an adhesive applied between the insert and the inside wall of the container. Practically, the adhesive would be applied between the base portion of the insert and the bottom of container. As an alternative to adhesives, the means may be provided by a sucker or suckers attached to either the insert or the container, and adapted to grip the other by means of suction cups.

A further alternative is provided by flexible magnets, which may be deployed, one inside the insert itself and another outside the base of the container. If a steel container is used then there may not be the need for the second container located magnet.

The base portion of the insert may be shaped, or profile to match the inner profile of the container bottom, this will assist location and increase the ability to secure the insert by the means described above.

In one particular arrangement of the present invention the thin walled section comprises two collars which are arranged to deform outwardly, and act like a bellows, the bellows forming the means which stabilise the insert in the drink container.

In another arrangement of the present invention the thin walled section is provided with scoring which acts to assist and control the collapse of the insert.

In another embodiment of the present invention the insert comprises a thin walled envelope having a base section and a top section wherein the envelope has at least one spiral of increased thickness extending between the base section and the top section.

The means to destroy the hermetic seal provided in accordance with the present invention can take any suitable form, and simply in its broadest term acts like a pressure actuated valve means.

In one arrangement the means comprises a deformable member which under the pressure differential variations experienced by the insert with regard to its ambient deforms and upon the drink container being opened deforms sufficiently to puncture on a spike. The spike could be

a solid or hollow like spike, for example a hypodermic needle to assist in the escape of gas from the insert to the beverage.

Clearly, any other suitable means could be used, such as a septum type device, favoured by some people.

In one particular embodiment made in accordance with the present invention the insert includes: a base section and a top section separated by a wall section, with sections together define a chamber, the insert being capable of collapsing when the external pressure increases above that within the chamber by a first predetermined amount and being capable of being held in that reduced volume state, and the insert further including valve means for releasing the contents of the chamber when the external pressure falls below that within the chamber by a second predetermined amount; in which the valve means comprises a septum of elastomeric material fixed against a section of the insert; said section having a first hole and the septum having a pinhole or slit adapted to communicate with the first hole ; the pin hole or slit being normally held closed by the resiliency of the septum but opening in the response to an external pressure lower than that within the chamber by the second predetermined amount, thus allowing the insert contents to be released into the container.

Preferably, the septum is fixed against the insert section by a guide member having an aperture in alignment with the pinhole or slit, the aperture being of a size such that the lower external pressure causes the septum to be deflected outwardly in a controlled manner through the aperture. The chamber may contain a gas or mixture of gases.

The invention will now be illustrated by way of description of several examples shown in the accompanying drawings, in which:

Figure 1 shows a schematic representation of a design of insert made in accordance with the present invention;

Figure 2 shows a schematic representation of a secured design of an insert made in accordance with the present invention;

Figure 3 shows a schematic representation of a third design of an insert made in accordance with the present invention;

Figure 4 shows a schematic representation of a fourth design of an insert made in accordance with the present invention;

Figures 5 to 9 show a schematic representation of the action of a fifth design made in accordance with the present invention;

Figure 10 shows a schematic representation of a sixth design of an insert made in accordance with the present invention;

Figure 11 shows a schematic representation of a seventh design of an insert made in accordance with the present invention.

Figures 12 and 13 show a schematic representation of an eighth alternative design of an insert made in accordance with the present invention;

Figures 14 and 15 show a schematic representation of a ninth alternative design of an insert made in accordance with the present invention;

Figure 16 shows a schematic representation of a suitable means to hold the insert in a collapsed position;

Figure 17 shows a schematic representation of a second suitable means to hold the insert in a collapsed position; and

Figure 18 and 19 show a schematic representation of a suitable alternative means to release the material into the drink.

Now referring to figure 1 of the accompanying drawings there is shown a first embodiment of an insert made in accordance with the present invention, which insert is intended for use with beer containers to be manufactured under standard manufacturing conditions.

The insert is manufactured from polypropylene and comprises two members which are adhesively adhered to one another. The insert comprises: a base section 1; a thin walled section 2 which is formed as a unitary member with the base section 1 and has an overall thickness of around 1.5 mm with an ultra thin section 3 having a thickness of around .35 mm; a top section 4 having circumferential groove 5 into which the thin walled section 2 remote from the base section 1 is adhesively secured, wherein the base section 1, thin walled section 2 and top section 4 define a space 6;

- a throughbore 7 which connects the space 6 with the surrounding atmosphere of the insert;

- a membrane 8 disposed across the throughbore 7 so as to hermetically seal the space 6 from the surrounding atmosphere; and

- a point 9 disposed so that it can puncture the membrane 8 when the pressure exceeds the ambient pressure by a sufficient degree.

The insert has an overall diameter of 50 mm and the height of 40 mm with a base thickness of around 10 mm, and is weighted so that it is base heavy in the installation condition. Further, the insert is weighted so that it does not tend to float to the top of the drink container when in use.

In addition the insert is provided with means in this case an interference fitting skirt 10, which stabilises the insert in the drink container and prevents the insert from moving about in the drink container.

In use the insert is disposed in the drink container so that the base section 1 of the insert contacts the base of the drink container. The drink container is then filled with the drink, and undergoes further treatments such as sealing of the container and pasteurisation of the drink contained therein in the normal fashion adopted by the industry. These processes act to increase the pressure in the drink container, and this increase in pressure causes the thin walled section 2, and in particular the ultra thin wall section 3, to collapse inwards so that the space 6 of the insert remains at a pressure substantially in equilibrium with the pressure of the surrounding atmosphere.

However, during storage of the drink container the pressure in the container is slightly relieved due to cooling of the container after pasteurisation, but the atmosphere pressure in the container remains above the ambient pressure to that of the drink container. In order to prevent the space 6 of the insert from increasing above that it has adopted in its collapsed state suitable means (not shown) is provided to prevent the insert re-establishing itself.

Consequently, the space 6 is maintained at a pressure in excess to its ambient pressure.

However this pressure is not sufficient to cause the membrane 8 to puncture on the point 9.

Vhen the drink container is opened, the pressure differential between the space 6 and the ambient significantly increases causing the membrane

8 to puncture on the point 9 and releasing the material in the space 6 through the puncture or possibly via the point 9 if this is hollow into the drink in the container. Normally, the material in the space 6 of the insert will be a gas and if the drink in the container is beer, frothing of the beer will occur.

In an alternative to the first embodiment of the present invention the insert as shown in figure 1 is formed from a suitable metal material, such as aluminium or mild steel and is substantially as described above. Similar numbers have been used to describe similar components, and therefore no further description will be given here.

If the insert is manufactured from aluminium the thin walled section 2 and 3 will have the following thicknesses 0.25 mm and 0.1 mm respectively.

The operation of the insert shown in figure 1 when the insert is formed from a metallic material is similar to that described above with regard to polypropylene.

However, with this embodiment the resilient nature of the metal material can be utilised in order to provide the means to retain the insert in the collapsed state and consequently no further means will be required.

Now referring to figure 2 of the drawings there is shown a second embodiment of an insert made in accordance with the present invention. This embodiment is substantially the same as that described with reference to figure 1 of the accompanying drawings and therefore similar numerals have been used to describe similar components and further description will not be given. However with this particular embodiment the thin walled sections 2 and 3 are provided with scoring 15 in order to assist and control the fashion in which the insert will collapse upon use, and exertion of a pressure differential.

In all other factors the insert is the same in design and operation to that previously described.

Now referring to figure 3 of the accompanying drawings there is shown a third embodiment of an insert made in accordance with the present invention. This particular embodiment of insert is very similar to that described with reference to figures 1 and 2 of the accompanying drawings and similar numbers have been used to describe similar components.

Consequently further description will not be given.

The difference with this particular embodiment from those previously described primarily relates to the method of delivery of the material in the space in the insert to the surrounding drink. In this embodiment a method of delivery uses a a septum type device disposed in the base section 1 of the insert.

An insert 11 is formed in the base section 1 and the throughbore 7 is disposed to communication between the insert 11 and the space 6.

A disc 12 having a central throughbore 13 is fully disposed in the insert 11, which disc 12 acts to locate and hold a septum 14 in position in the inset between the base section 1 and the disc 12.

The septum 14 is formed from an elastomeric polymer which has a slot formed therein which is normally closed due to the resiliency of the polymer.

Furthermore, the septum is supported by the base section 1, the throughbore 7 being large enough to allow communication between the space 6 and the exterior of the insert but small enough to prevent the septum 14 from deforming inwardly and opening the throughbore 7 when the exterior pressure becomes greater than the pressure within the space 6.

On the other hand, the central bore 13 of the disc is large enough to allow the septum to open when the exterior pressure falls below that within the space 6, such as will occur when the container is opened, thus breaking the hermetic seal. The septum 14 is in alignment with the throughbore 13 and is only able to deflect in the location of the throughbore 13 so that the disc 12 also serves to control the opening of the septum and the particular pressure at which the septum is driven outwards sufficiently to open.

In the figure, both the throughbore 7 of the insert and the central bore 13 of the disc are in general alignment, so that on release of the pressure in the drink container the material in the space flows through the aligned throughbore. Clearly it is essential only that the throughbores can communicate in some way to allow material in the space to escape from the insert.

Now referring to figure 4 of the accompanying drawings there is shown in a fourth embodiment an alternative septum device to that described with reference to figure 3 of the accompanying drawings. Similar

numbers have been used to describe similar components, and no further description of these components will be given here.

In this particular arrangement the disc 12 is not fully disposed in the inset 11.

Now referring to figure 5 of the accompanying drawings there is shown a fifth embodiment of insert made in accordance with the present invention and disposed in a drink container.

This particular embodiment works in a bellows type fashion. The insert comprises:- an outer member 101 having a generally cup shaped configuration which when disposed in the drink container is in an inverted position; a membrane 103 disposed towards the open end of the member 101 and which acts to define a space 104 with the member 101; and a disc like member 105 having a number of apertures 106 and a point 107 which is disposed in the open end of the member 101 but not in the space 104.

The member 101 is formed from polypropylene with a general thickness of 1.5 mm and comprises: an end section 108; and a circumferential wall 109 with two circumferentially extending collars 110 of reduced thickness, the collars having a thickness of 0.35 mm.

The member 101 is provided with scoring 111 in its outer surface in the area adjacent to the boundary of the collars 110 with the areas of greater thickness in the wall member and scoring 112 in the inner surface of the member 101 centrally within the collars 110.

The insert is weighted so that when surrounded by drink there is no tendency for the insert to float.

In use the insert is disposed in the drink container so that the open end of the member 101 of the insert contacts the base of the drink container. The drink container is then filled with drink and undergoes further treatments such as sealing of the container and pasteurisation of the drink therein in the normal fashion used in the industry. These operations/treatments act to raise the pressure in the drink container and this increase in pressure causes the two circumferentially extending collars 110 to deform outwardly along the scoring lines 111 and 112 so

as to form a bellows as shown in figures 6 to 9 of the accompanying drawings during collapse of the insert.

Ultimately, this causes the pressure in the space 104 to increase so that it equilibriates with the surrounding atmosphere pressure.

In the fully collapsed state the bellows sections (collars 110) are flat forming two skirt members which act to stabilise the insert in the drink container. Now during storage due to the cooling of the drink subsequent to pasteurisation the pressure in the drink container is slightly relieved but the atmosphere pressure in the container remains above that of the surrounding atmosphere to the drink container. In order to prevent the space 104 of the insert from increasing above that it has adopted in the collapsed state suitable means (not shown) is provided to prevent the insert from re-establishing itself. Consequently the space 104 is maintained at a pressure in excess to its immediate ambient pressure. However, this pressure differential is not sufficient to cause the membrane 103 to be punctured by the point 107.

Vhen the drink container is opened, the pressure differential between the space 104 and the ambient significantly increases causing the membrane 103 to puncture on the point 107 and so releasing the material in the space 104 through the puncture, or possibly via the point 107 if this is hollow into the drink

In an alternative to the fifth embodiment of the present invention the insert as shown in figure 5 of the accompanying drawings is formed from a suitable metal material, such as aluminium or mild steel, and is substantially as described above.

If the insert is manufactured from mild steel the reduced thickness collars of the member 101 have a thickness of 0.15 mm whilst the general thickness of the member 101 is 0.25 mm.

Now referring to figure 10 of the accompanying drawings there is shown a sixth embodiment of insert made in accordance with the present invention.

The insert is formed from polypropylene and comprises: a base member 201; an inverted cup shaped member 202 with a general thickness of 0.35 mm; means 203 for retaining the cup shaped member in a position; a membrane 217 _:

and, a disc shaped member 204 with a series of apertures 205 and a point 206, which is disposed below the membrane 217.

The base member 201 has: a groove 207 circumferentially extending around the top surface of the base member 201 towards the periphery of the base member; a centrally disposed throughbore 208; and, a series of holes 209 between the groove 206 and the edge of the base member 201.

The inverted cup shaped member 202 is formed with generally uniformed thickness, and has an end section 210 and a circumferential wall section 211 surrounding the end section 210. The wall section 211 is adhesively adhered to the groove 207 in the base member 201.

A circumferentially extending collar 213 extends around the. outside of the end section 210 and circumferential wall section 211 of the inverted cup shaped member 202. A series of holes 214 is formed in the collar 213 so that these holes may co-operate with the series of holes 209 in the base member 201.

Further, a bead 214 having an increased thickness of 2.5 mm is formed in the wall section 211 in a spiral configuration running from the base section 201 to the end section 210.

The means 203 for retaining the insert in a position comprises: a number of posts 215, each of which is disposed in a hole in the series of holes 209 and extends through a hole in the circumferentially extending collar 213 of the inverted cup shaped member 202; and detent conical formations 216 formed on the posts which pass through the holes in the collar in one direction but are prevented from doing so in the other direction.

Vhen assembled the base member 201 an inverted cup shaped member 202 define a space 218 in which adjacent the base member 201 is disposed the membrane 217. In this fashion the membrane seals the material in the space 218.

In use the insert is disposed in the drink container so that the base member 201 of the insert is in contact with the base member of the drink container. The drink container is then filled with drink, and undergoes further treatments such as sealing of the container and pasteurisation

of the drink in the normal fashion used in the industry. This acts to raise the pressure in the drink container, and this increase in pressure causes the inverted cup shaped member 202 to collapse and the posts 215 with detent conical formations 216 to move through the holes in the collar 213 of the inverted cup shaped member 202. The end of the post 215 are thus moved outwardly and engaged with the walls of the drink container so as to stabilise the insert in the drink container with regard to the walls thereof.

Consequently, as the insert collapses the pressure in the space 218 increases and equilibriates with the atmosphere pressure in the drink container.

Now during storage the pressure in the drink container is slightly relieved, due to the cooling subsequent to the pasteurisation operation, but the pressure in the container remains above that of the surrounding atmosphere to the drink container. The detent conical formations 216 on the post 215 engage with the holes in the collar 213 of the inverted cup member 202 to hold the insert in the collapsed state.

As a result of this the pressure in the space 218 is held above that of the surrounding atmosphere pressure, but the pressure differential is not sufficient to cause the membrane 217 to puncture on the point 206.

Vhen the drink container is opened the pressure differential between the space 218 and the surrounding atmosphere significantly increases causing the membrane 217 to puncture on the point 206 so releasing the material in the space 218 through the puncture, or possibly via the point 206 if this is hollow, into the drink in the container.

Now referring to figure 11 of the accompanying drawings there is shown seventh embodiment made in accordance with the present invention. This embodiment is similar to that shown and described with reference to figure 10 of the accompanying drawings, and similar numbers have been used to describe similar components. Consequently no further description of these components will be given here.

The difference between this embodiment and the previous embodiment is in the fact that the membrane 217 is disposed in the upper surface of the inverted cup member 202, with the point 206 being disposed there above. Consequently, the insert is formed as a unitary member.

The operation of this insert is similar to that described with regard to the previous embodiment.

It should however be noted that the means 203 for retaining the insert in position described with reference to figure 6 the accompanying drawings could be used with the inserts described with reference to figures 1 to 3 of the accompanying drawings.

Now referring to figures 12 and 13 of the accompanying drawings in which there is shown an eighth embodiment made in accordance with the present invention. In this embodiment the insert is formed from polypropylene and comprises:

- a cylindrical side wall 250 having a thickness of 0.25 mm;

- a top surface 251 having the same thickness as the cylindrical side wall 250, and being joined to the cylindrical side wall by webbing 252 which has a thickness of 0.2 mm _;

- a bottom surface 253 having the same thickness as the cylindrical side wall 250 and being joined to the cylindrical side wall by webbing 254 which has a thickness of 0.2 mm; and

- a valve means 255 formed in the top surface 251.

The cylindrical side wall 250, top surface 251, bottom surface 253 and webbings 252 and 254 define a space 256 which is hermetically sealed from the surrounding environment.

The valve means 255 is a septum type device of the same general class as described with reference to Figures 3 and 4 of the accompanying drawings and such basic description is incorporated herein by way of reference.

The insert will also be provided with means (not shown) which stabilise the insert in the drink container and prevent the insert from moving about in the drink container.

In use the insert is disposed in a drink container so that the bottom surface 253 of the insert contacts the base of the drink container. The drink container is then filled with drink, and undergoes further treatment such as sealing of the container and pasteurisation of the drink contained therein in a normal fashion adopted by the industry. These processes act to increase the pressure in the drink container, and this increase in pressure causes the top surface 251 and bottom surface

253 to move towards one another and therefore the space 256 to collapse inwards so that the atmosphere in the insert remains at a precious substantially and equilibrium with a pressure of the surrounding atmosphere.

However, during storage of the drink container the pressure in the container is slightly relieved due to cooling of the container and its contents after pasteurisation, but the atmosphere pressure in the container remains above the ambient pressure to that of the drink container.

The angular relationship, and thickness of the polypropylene from which the insert is made, of the cylindrical side wall 250, top surface 251, bottom surface 253, and the respective webbings 252 or 254 act as the means to prevent the insert re-establishing itself during this cooling. Consequently, the space 256 is maintained at a pressure in access to its ambient pressure. However, this pressure, or more particularly the pressure differential between the space and the surrounding atmosphere is not sufficient to open the septum and cause release of the material within the insert.

Vhen the drink container is opened, the pressure differential between the space 256 and the surrounding atmosphere significantly increases causing the septum to open so releasing the material in the space through the septum and into the drink in the container. Normally, the material in the space 256 of the insert will be a gas and if the drink in the container is beer, frothing of the beer will occur.

In an alternative arrangement of this embodiment the device is manufactured from aluminium and/or mild steel and the appropriate wall thicknesses mentioned above with regard to other embodiments are adopted.

Now referring to figures 14 and 15 of the accompanying drawings in which there is shown a ninth embodiment made in accordance with the present invention. In this embodiment the insert is formed from a coated metal and comprises a drawn cup having a base 263 and a cylindrical side wall 260 joined to an end 261 by a seaming operation or other conventional technique.

The base 263 and side wall 260 are of substantially the same thickness, for example 0.27 - 0.28 mm, and the end 261 is slightly

thinner, for example 0.223 or 0.235mm, although it may be the same thickness as the base and side wall. The height of the side wall is limited to less than 30 mm in order to prevent the side wall from deforming during pressurisation.

The base 263 of the cup is formed with a septum-type valve 266 which has been described in more detail with reference to figures 3 and 4 above. Alternatively, the septum may be formed in the end 261, if preferred.

The insert wall, base and end together define a space or chamber 256 which is hermetically sealed from the surrounding environment by the septum.

The insert will also be provided with means (not shown) which stabilise the insert in the drink container and prevent the insert from moving about in the drink container.

The use of metal for forming the insert ensures that the base and end are maintained in their deformed state and the insert is prevented from re-establishing itself during cooling in storage.

The septum is designed so that any increase in external pressure is not capable of opening it, even after the insert has collapsed. Furthermore, the large throughbore in a disc is used to control the ' pressure at which the septum opens so that the septum will open when the drink container is opened. Vhen this occurs, the pressure differential is such that the septum opens and material is released from the chamber through the septum and into the drink in the container. Normally, the material is gas, so that if the drink in the container is beer, frothing of the beer will occur.

In an alternative embodiment of this device, the insert is manufactured from a non-toxic polymer but most polymers will require means for locking the insert in its collapsed state and the thickness of the insert will need to be adjusted to ensure that deformation occurs as required. Metal is, however, a preferred material for the insert provided that it is coated in some way since it is more environmentally acceptable than are plastics materials.

In the use the insert is disposed in a drink container so that the bottom surface 263 of the insert contacts the base of the drink container. The drink container is then filled with drink, and undergoes

further treatment such as sealing of the container and pasteurisation of the drink contained therein in a normal fashion adopted by the industry. These processes act to increase the pressure in the drink container, and this increase in pressure causes the end 261 and base 263 to move towards one another and therefore space 266 to collapse inwards so that the atmosphere in the insert remains at a pressure substantially in equilibrium with a pressure of the surrounding atmosphere.

Although during storage of the drink container the pressure in the container is slightly relieved due to cooling of the container and its contents after pasteurisation, the atmospheric pressure in the container remains above the ambient pressure to that of the drink container.

Now referring to figure 16 of the accompanying drawings there is shown one form of means to retain the insert in the collapsed condition.

This arrangement an angled collar member 301 is formed on an outer shell member 302 which moves down as the insert collapses and pushes a number of posts outwardly so that they engage with the sides of the drink container. At the same time the post 304 moves through holes, and detent means 305 on the post engaged with the holes to prevent the insert from re-establishing itself.

Now referring to figure 17 of the accompanying drawings a second arrangement of means to retain the insert in a position is shown. This arrangement is similar to that described above with regard to figure 12 of the accompanying drawings except that the posts 304 act against a second set of posts 306 which then engaged the sides of the drink container

Now referring to Figure 18 and 19 of the accompanying drawings, there is shown a form of mechanism to enable the release of the material within the space in the insert into the drink. This is an alternative arrangement to those discussed above and can be used as a simple substitution for those mechanisms.

The mechanism as shown can be formed in the base, top or wall section of an insert in accordance with the present invention and comprises a section 350 of reduced thickness, (although this is not essential), formed in the insert which section 350 has formed therein one a more apertures 351 (in this case a circular pattern of six aperatures is shown). A sealing ring 352 is secured over the section 350 and is

hermatically sealed to the insert so that the space in the insert is isolated from drink contained in the drink container.

The sealing ring 352 is formed from a suitable material, such as a laminate of polypropylene. Aluminium foil and polypropylene, and comprise :

- an adhering portion 353 which is adhered to an insert on which the ring 352 is to be used;

- a central flap section 354; and

- a retaining means 355.

The adhering portion 353 and central flap section 354 are separated from one another, over a significant proportion of these length by rupturable means 356. This rupturable means may for example comprise a weakened section, which does not when formed include any perforations enabling communication between the two sides of the sealing ring 352.

The weakened section shown may have a break therein to act like a hinge once the rupturable means rupture. This constitutes in this particular embodiment the retaining means 355.

It will however be well appreciated in the industry that with this form of device more than one break could be incorporated in the weakened section and form a weakened section having a number of retaining sections to form the retaining means.