EP0758996B1

EP0758996B1 - Method of pressurising inserts

Info

Publication number: EP0758996B1
Application number: EP95918052A
Authority: EP
Inventors: David Wilson Pennell; David Neil Wragg; Clive Scott Coleman
Original assignee: STYGIAN Ltd
Current assignee: STYGIAN Ltd
Priority date: 1994-05-04
Filing date: 1995-05-04
Publication date: 1998-12-09
Anticipated expiration: 2015-05-04
Also published as: AU2413195A; GB9408800D0; WO1995030603A1; EP0758996A1

Description

This invention relates to a method of providing a pressurised gas in an insert for release into a beverage.

It is becoming increasingly popular to provide an insert inside a beverage can in which the insert contains a pressurised gas which is released into the beverage when the can is opened.

A number of methods have been used to provide an insert with a valve means, charged with pressurised gas, positioned in a sealed beverage can.

In one method, the gas inside the insert can be charged to super-atmospheric pressure at the time of forming the insert and the insert placed in the beverage can in a super- atmospheric atmosphere. This means that there is no pressure differential across a valve of the insert; no gas will escape from the insert which would otherwise cause a lowering of the internal pressure of the insert.

This method requires major alteration to a canning line to be put into effect as a beverage can containing the charged insert must be kept at super-atmospheric pressure during filling and sealing.

A second method is to fill the insert with a gas at atmospheric pressure and to increase the pressure of the gas within the insert once it is placed and sealed within the beverage can. An increase in pressure within the insert can be produced by reduction of the volume of the insert or by means of the insert having a gas permeable wall through which gas can enter the insert from the surrounding beverage until the gas pressure within the insert is equal to the pressure of the surrounding beverage.

These two methods both have disadvantages. The first method necessitates a reduction of the speed of the canning line. The second method requires the insert either to have moving parts or to be formed of a deformable material, the deformation of which may not be uniform across a number of inserts, or to rely on a gas permeable material for transfer of the gas into the insert.

WO-A-92/00896 discloses an insert having a closable orifice for releasing a pressurised gas within a beverage container, the insert comprising an insert cap attached to an insert body in which the insert cap has a first state in which it has a connection portion and a resilient substantially accurate portion and a second, elastically deformed state in which the cap is retained at the insert body by attachment of its connection portion to the insert body to close the insert.

EP-A-594 221 discloses a pasteurisation step applied to an insert.

According to a first aspect, the present invention provides a method of providing a pressurised gas in an insert formed, at least in part, of a thermally modifiable plastics material for release into a beverage comprising the steps of:

(a) providing an insert cap and an insert body which are assembled able to form the insert, the insert cap being provided in a first state in which it has a connection portion and a resilient, substantially arcuate body portion;

(b) assembling the insert body and the insert cap together, in a gas at super atmospheric pressure with an initially convex surface of the body portion of the cap arranged towards the insert body, by deforming the body portion of the cap, maintaining it in a second, elastically deformed state at the insert body such that an orifice of the insert is blocked by a projection member to close the insert, and fixing the connection portion of the cap to the insert body to form the insert and seal the super atmospheric pressure gas within the insert body characterised by;

(c) reducing the pressure surrounding the insert to atmospheric pressure, the resilience of the cap causing it to be retained at the insert body to prevent substantial release of pressurised gas from the insert;

(d) placing the insert in a container, filling the container with a beverage and sealing the container;

(e) increasing the temperature of the insert within the container, causing the cap to undergo plastic deformation to assume a third, relaxed, state at which it is maintained at the insert body and in which state reduction of the pressure externally of the insert to substantially atmospheric pressure causes the cap to deform causing gas to be released from inside the insert.

According to a second aspect, the present invention provides an insert formed, at least in part, of a thermally modifiable plastics material having a closeable orifice for releasing a pressurised gas within a beverage container, the insert comprising an insert cap which can be attached to an insert body in which insert cap has a first state in which it is not attached to the insert body and it has a connection portion and a resilient substantially arcuate body portion with an initially convex surface arranged towards the inset body and a second, elastically deformed state in which the cap is retained at the insert body in by attachment of its connection portion to the insert body at super atmospheric pressure such that the orifice is blocked by a projection member to close the insert characterised in that the pressure surrounding the insert may be reduced to atmospheric pressure, wherein the resilience of the cap causes it to be retained at the insert body to prevent substantial release of pressurised gas from the insert; the insert cap undergoing plastic deformation to assume a third, relaxed, state in response to a raising of temperature of the insert, in which the insert cap is maintained at the insert body, such that the insert cap is deformable in response to a reduction in external pressure to substantially atmospheric pressure to cause gas to be released from inside the insert;

The method and apparatus of the present invention cannot be deduced from examination of the insert as provided in a beverage can before, during or after operation of the insert.

Preferably, the projection member is attached to the insert body and the orifice is provided in the cap.

Preferably, the insert body is provided in the form of a cup-shaped member.

Preferably, the cap is deformed around the projection member upon being assembled with the insert body, the projection member acting against the cap to cause it to assume its second state when attached to the insert body.

Preferably, the temperature of the insert within the container is raised by subjecting the container and the beverage therein to a pasteurisation process.

Preferably, the insert cap comprises a ridge on an internal circumference of the insert cap which acts against a rim of the insert body to seal the insert cap against the insert body.

Embodiments of the present invention will now be described with reference to the accompanying drawings in which:

Fig 1 is a cross-section of the components of an insert in accordance with the present invention, before assembly;

Fig 2 is a cross-section of the insert of Fig 1 when assembled; and

Fig 3 is a cross-section of the insert of Fig 1 during operation of the insert on opening a beverage container in which the insert is disposed.

Referring to the drawings, a diagrammatic cross section of the insert 10 is shown in Fig 1. The insert has two opposing walls 1, 2. This first wall 1, which is disposed at the top of the insert 10, has an orifice 3 in its centre. The orifice 3 has a surround 4 which co-operates with a top 5 of a projection member in the form of a stem 6 which projects from an internal face 7 of the second wall 2.

The first wall 1 is in the form of a cap 8 which clips onto an insert body in the form of a cup shaped member 9 of which the second wall 2 is the base.

Prior to assembly of the cap 8 onto the cup shaped member 9, the cap 8, when not subjected to external forces, has a body portion having a curved, convex or arcuate form such that its centre, at which orifice 3 is positioned, curves inwardly in relation to the surrounding rim 12 of the cap 8.

The cap 8 is formed of a resilient material and clips onto the cup member 9 with an interference fit between the rim 12 of the cap 8 (which provides a connection portion) and the rim 13 of the cup member 9.

The insert 10 is designed such that the composite height h1 of the projecting stem 6 and the orifice surround 4 is of greater height than the distance h2 between the two walls 1,2 at their circumferences including the fully extended inter-locking join of the cap 8 to the cup member 9. This means that the first wall 1 is forced to curve around the stem 6 in a concave manner when the cap 8 is pressed onto the cup member 9 and the top 5 of the stem 6 is forced against the surround 4 of the orifice 3 thereby closing the orifice 3.

The resilience of the cap 8 of the insert 10 is such that the insert 10 can be assembled under a pressure of approximately 34 psi and the cap 8 forced onto the cup member 9 enclosing the gas at a pressure of 34 psi within the insert 10.

The pressure external to the insert 10 is reduced slowly to atmospheric pressure and the resilience or spring of the cap 8 of the insert 10 is such that substantially no gas escapes from the orifice 3 even though there is a large pressure difference between the pressures inside and outside the insert 10.

It is important to ensure that the cap 8 does not pop off inadvertently due to the resilience or spring of the cap 8 not being sufficient. Alternatively, if the resilience or spring of the cap 8 is too strong, operation of the insert 10 will be impaired. The resilience of the cap 8 is determined by the dimensions of the cap and flexibility and nature of the material from which it is made.

The insert 10 is inserted into the can and the can is filled with a beverage and sealed. After sealing, the can is pasteurised. During pasteurisation the pressure of the beverage inside the can rises considerably due to the rise in temperature. The pressure inside the insert 10 also rises due to the increase in temperature of the gas; however, due to the fact that the pressure of the beverage external to the insert 10 is greater than the internal pressure of the insert 10, no gas escapes from the insert 10 during this time.

When the plastics material of which the insert is made is heated, as occurs during pasteurisation, it creeps slightly and as it is under pressure the cap 8 creeps more into the position it is held in by the external pressure in relation to the cup member 9. Due to the creep in the plastics material, the resilience or spring of the cap 8 is weakened a little but, once cooled, the pressure external to the insert 10 is sufficient to ensure that the orifice 3 remains closed until the beverage can is opened.

When the can is cooled after pasteurisation the pressure within the insert 10 falls back to its original filling pressure of approximately 34 psi. The pressure in the beverage external to the insert 10 remains at a higher pressure enabling the cans to be transported without risk of the gas escaping from the insert 10.

When the can is opened, the pressure in the beverage surrounding the insert 10 drops suddenly to atmospheric pressure. This sudden drop in pressure causes the resilient cap 8 of the insert 10 to spring away from the stem 6 which projects from the second wall 2 of the insert 10 thus allowing some gas to escape through the orifice 3. The seal between the cap 8 and the cup member 9 must be sufficiently strong to prevent the cap 8 coming away from the cup member 9 during this decrease in external pressure. Not all the gas escapes through the orifice 3 as the cap 8 of the insert 10 quickly springs back to rest on the stem 6. This means that some pressurised gas remains in the insert 10.

Due to the fact that the operation of the insert 10 depends on the resilience or spring of the cap 8 of the insert 10, the dimensions of the cap 8 are extremely important. Also, the seal between the cap 8 and the cup member 9 of the insert 10 is very important and a slight ridge 11 on the internal circumference of the cap 8 is provided which acts against the rim 13 of the cup member 9 holding the seal between the cap 8 and the cup member 9 together even when the cap 8 is tensioned and is curved around the stem projection 6.

This operation may vary slightly in that the base of the cup member 9 may curve outwardly as well as or in place of the cap 8.

Modifications and improvement may be made without departing from the scope of this invention as claimed.

Claims

A method of providing a pressurised gas in an insert (10) formed, at least in part, of a thermally modifiable plastics material for release into a beverage comprising the steps of:

(a) providing an insert cap (1) and an insert body (2) which are assembleable to form the insert (10), the insert cap (1) being provided in a first state in which it has a connection portion and a resilient, substantially arcuate body portion;

(b) assembling the insert body (2) and the insert cap (1) together, in a gas at super atmospheric pressure with an initially convex surface of the body portion of the cap (1) arranged towards the insert body, by deforming the body portion of the cap (1), maintaining it in a second, elastically deformed state at the insert body (2) such that an orifice (3) of the insert is blocked by a projection member (6) to close the insert, and fixing the connection portion of the cap (1) to the insert body (2) to form the insert and seal the super atmospheric pressure gas within the insert body;
characterised by;

(c) reducing the pressure surrounding the insert to atmospheric pressure, the resilience of the cap (1) causing it to be retained at the insert body (2) to prevent substantial release of pressurised gas from the insert;

(d) placing the insert (10) in a container, filling the container with a beverage and sealing the container;

(e) increasing the temperature of the insert (10) within the container, causing the cap (1) to undergo plastic deformation to assume a third, relaxed, state at which it is maintained at the insert body (2) and in which state reduction of the pressure externally of the insert to substantially atmospheric pressure causes the cap (1) to deform causing gas to be released from inside the insert (10).
A method in accordance with claim 1, in which the projection (6) member is attached to the insert body (2) and the orifice (3) is provided in the cap (1).
A method in accordance with any preceding claim in which the insert body (2) is provided in the form of a cup-shaped member.
A method in accordance with any preceding claim in which cap (1) is deformed around the projection member (6) upon being assembled with the insert body (2), the projection member (6) acting against the cap (1) to cause it to assume its second state when attached to the insert body (2).
A method in accordance with any preceding claim in which the temperature of the insert (10) within the container is raised by subjecting the container and the beverage therein to a pasteurisation process.
An insert (10) formed, at least in part, of a thermally modifiable plastics material having a closeable orifice (3) for releasing a pressurised gas within a beverage container, the insert comprising an insert cap (1) which can be attached to an insert body (2) and which insert cap (1) has a first state in which it is not attached to the insert body and it has a connection portion and a resilient substantially arcuate body portion with an initially convex surface arranged towards the insert body and a second, elastically deformed state in which the cap (1) is retained at the insert body (2) by attachment of its connection portion to the insert body (2) at super atmospheric pressure such that the orifice (3) is blocked by a projection member (6) to close the insert (10) characterised in that the pressure surrounding the insert may be reduced to atmospheric pressure, wherein the resilience of the cap (1) causes it to be retained at the insert body (2) to prevent substantial release of pressurised gas from the insert; the insert cap (1) undergoing plastic deformation to assume a third, relaxed, state in response to a raising of temperature of the insert (10), in which the insert cap (1) is maintained at the insert body (2), such that the insert cap (1) is deformable in response to a reduction in external pressure to substantially atmospheric pressure to cause gas to be released from inside the insert (10).
An insert according to claim 6 in which the insert cap (1) comprises a ridge (11) on an internal circumference of the insert cap (1) which acts against a rim (13) of the insert body (2) to seal the insert cap (1) against the insert body (2).