WO2015110782A1

WO2015110782A1 - Container with foil check valve

Info

Publication number: WO2015110782A1
Application number: PCT/GB2015/000012
Authority: WO
Inventors: Neil COLEY
Original assignee: Discovery Flexibles Limited
Priority date: 2014-01-21
Filing date: 2015-01-20
Publication date: 2015-07-30
Also published as: GB201400974D0

Abstract

An improved apparatus and method for releasing excess gas from a container. The container has a gas tight wall which forms a product containing cavity, an outer wall and a one way valve for allowing gas to leave the cavity. The valve has a first perforated layer which forms part of the gas tight wall of the cavity, a second perforated layer which forms part of the outside of the container. The first perforated layer and the second perforated layer are joined together such that an enclosed volume is formed between the first perforated layer and the second perforated layer. The gas tight layer prevents the flow of gas from the container when in a first position and allows gas to move through the valve when in a second position. The second position if the layer is caused by overpressure in the cavity.

Description

CONTAINER WITH FOIL CHECK VALVE

Introduction The present invention relates to an apparatus for gas over-pressure release which is suitable for use in packaging for products that develop gas, in particular powder or granular products, such as coffee, food products in general, detergents and others. One purpose of the invention is to create a package which prevents the build-up of excess gas within the packaging after the packaging has been sealed.

Background

Some products release gas after they have been processed into their final form before packaging. However, in order to maintain the quality and freshness of the product it is very important that the product is sealed within its packaging as soon as possible after it has been processed, one consequence of this is that gas is released after the product has been sealed in its container.

Ground roasted coffee beans, for example, give out significant amounts of carbon dioxide and aromatic gasses after the product has been packaged If roasted coffee is stored in gas-tight soft packaging, the creation of significant amounts of excess gas within the sealed container will cause the package to bulge and greatly increase the risk that the package will burst. For this reason packaging in which fresh ground coffee is contained requires a one way vent applied to it to allow the coffee to "de- gas". The de-gassing process can take from 12 to 48 hours and can be affected by storage conditions, temperature and type of coffee being packed. Currently there are 2 main solutions to applying a vent to the bag. Both of these solutions are outlined below. Solution 1 - The Diaphragm Valve

The diaphragm valve is applied during the bag forming process on a packing line. The valve is heat sealed in register onto the film prior to bag formation. At the same time as the valve is being applied a hole is pierced allowing a free venting area on the bag.

The diaphragm valve also known as an overpressure or degassing valve is a one- way valve which is normally applied to the upper wall of the container and whose purpose is to allow the gases developed by a product, to escape from the container in order to avoid the possible build up of internal overpressure. The one-way valve also prevents air from entering the container because contact with air will impair the quality of the product.

Typical one way valves comprise a small, rigid, disc shaped element which extends through one surface of the packaging and it is usually positioned towards the top of the package near the area of the intended opening section of the package. Figure 1 shows a typical container suitable for holding ground roasted coffee. The container 1 has an outer printable surface layer 3, an openable sealed top edge 7 and a degassing valve 5 positioned on the front surface of the container.

US 4444219 discloses an example of a valve for releasing overpressure in a sealed package which has flexible walls. The valve body has a flat valve seat having thereon a diaphragm with a valve shutting part. In the seat there are valve openings, each having a number of concentric ring-like channels round it in the seat. The concentric channels take up a sealant such as silicone oil. The diaphragm is made of a single piece of material running from one side of the walls to the other without any holes therein. It is kept in position in a middle part of the valve seat so that the diaphragm may be moved freely, at least over the valve openings.

EP 1538107 discloses another example of a degassing valve. In this case, the valve comprises a base body or plate with a first hole with a smaller diameter for the passage of the gases and a second hole with a larger diameter for expansion of the gases. A cap provided with an outlet hole for discharge of gas is coupled to the base body, and a mobile diaphragm is positioned between the base body and the cap to open/shut-off the passage of gas from the second expansion hole to the outlet hole. One problem with this type of vent is that the machine used to apply the valve and pierce the bag is only available from a very limited number of companies. In addition, the valves are expensive typically adding significantly to the cost of manufacture. The throughput on these types of machine is typically slower than on standard form- fill and seal machines. The advantage of this system is that the bag has a venting solution that is robust and has been in use for many years.

Taking the example of freshly ground coffee, packaging is prepared by creating a suitable type of soft packaging bag and in a separate process, presenting the bag to a coffee valve applicator machine which inserts the degassing valve into and through one face of the bag and seals the valve in position.

Solution 2 - Label Application

There are 2 main label applications currently used to apply a vent to a package.

Type 1 involves a film being pierced and a label being applied just after a dose of oil has been placed over the holes. This can be intricate and if the oil dosage is too little or too much the bags can fail. The maintenance and security of the label is not as good as the valve but typically the machinery for applying the label is cheaper as is the overall cost per bag.

Type 2 is the same as type 1 described above except that the labels are already pre- treated with oil. The cost of the labels is high and available only from the label manufacturer.

Packaging to which valves or labels of the type described above, are applied require several additional process steps in comparison with packaging where no such gas pressure release means is needed. These solutions increase the cost and time for packaging production.

Summary of the Invention

It is an object of the present invention to provide an improved apparatus for releasing excess gas from a container. In accordance with a first aspect of the invention there is provided a container adapted to prevent a build up of gas therein, the container comprising:

at least one gas tight wall which forms a cavity in which a product may be enclosed;

a one way valve for allowing gas in the cavity at higher pressure than the ambient pressure outside the cavity to leave the cavity, the valve comprising: a first perforated layer which forms part of the gas tight wall of the cavity;

a second perforated layer which forms part of the outside of the container, the first perforated layer and the second perforated layer being joined together such that an enclosed volume is formed between the first perforated layer and the second perforated layer; a gas tight layer in a first position across the first perforated layer to prevent the flow of gas to and from the container and wherein the gas tight layer is moved from the first position when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure such that gas may flow through perforations in the first perforated layer, through the enclosed volume and through perforations in the second perforated layer.

Preferably, the gas tight layer comprises a strip of material removeably connected in the first position across the first perforated layer by fixing means to prevent the flow of gas to and from the container and wherein the gas tight layer is moved from the first position when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure such that gas may flow through perforations in the first perforated layer, through the enclosed volume and through perforations in the second perforated layer. Alternatively, the gas tight layer comprises a fluid material of suitable viscosity such that when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure, the fluid is moved from a position where it prevents flow of gas through the first and second perforated layers to one where it allows gas to flow. Preferably, the fluid is applied in situ between the first layer and the second layer and to ensure that the area of the package in which the fluid is present is left unsealed when a heat-seal is applied to the container.

Preferably, the fluid remains filling the void where the first layer and the second layer are not sealed to create a channel for gas from the container to vent gas when a higher gas pressure exists in the container than is present outside the container. The gas will pass through and out of the pack by forcing the oil away from the top of the pack when venting. The oil will then move back to fill the opening when the coffee has stopped venting.

Preferably, the container is a soft packet.

Optionally, the container is made at least in part from rigid material

Optionally, the container is made at least in part from flexible material. Preferably, the first perforated layer is integrally formed with the wall of the cavity

Preferably, the second perforated layer is integrally formed with the outside of the container. Preferably, the outside of the container comprises an outer layer of printable material bonded to a layer of foil.

Preferably, the foil is aluminium foil. Preferably, the outside layer printable material may be selected from one of the following materials oriented polypropylene (OPP), cast polypropylene (CPP), oriented polyamide (OPA), polyethylene (PE) or polyethyleneterephthalate (PET)

Preferably, the first perforated layer is integrally formed with the wall of the cavity. Preferably, the gas tight layer comprises a filmic thermoplastic. Preferably, the filmic thermoplastic is made from polyethylene.

Preferably, the filmic thermoplastic is made from low density polyethylene (LDPE).

Preferably, the gas tight layer is a strip extending down one wall of the container through the enclosed volume.

Optionally, the gas tight layer is substantially circular.

Preferably, the fixing means has a suitable peel strength such that it will move to the second position when an overpressure exists within the container.

Advantageously, the fixing means may reseal the gas tight layer to the first perforated layer once the pressure inside the cavity has reduced to a level at or near to the ambient pressure. Preferably, the fixing means is an adhesive.

Optionally, the fixing means is a sealant.

Preferably, the fixing means is a liquid.

Advantageously, a liquid fixing means of suitable peel strength and viscosity affects the seal and release of the gas tight layer from the first perforated layer by movement of the liquid into and out of contact with the gas tight layer and the first perforated layer.

Preferably, the fixing means is a mineral oil.

Preferably, the perforations are sized to prevent the fluid from entering the cavity. Preferably the perforations are made using a laser.

Optionally, the perforations are holes punched into the respective layers. Optionally, the perforations are cuts made in the respective layers.

In accordance with a second aspect of the invention there is provided a method for making a container which has an integrated one way valve, the method comprising the steps of:

creating an outer layer of the container;

perforating one or more predetermined parts of the outer layer to create a second perforated layer;

creating an inner gas tight wall which forms a cavity in which a product may be enclosed;

perforating one or more predetermined parts of the inner layer to create a first perforated layer;

bonding the outer layer of the container to the inner gas tight layer layer such that the area around the second perforated layer and the first perforated layer is not bonded and forms an enclosed volume;

introducing a gas tight layer into the enclosed volume either before or after the enclosed volume has been formed

wherein the gas tight layer is removeably connected in a first position across the first perforated layer to prevent the flow of gas to and from the container and wherein the gas tight layer is moved from the first position when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure such that gas may flow through perforations in the first perforated layer, through the enclosed volume and through perforations in the second perforated layer.

Preferably, the step of introducing a gas tight layer further comprises introducing a fixing means into the enclosed volume either before or after the enclosed volume has been formed

wherein the gas tight layer is removeably connected in a first position across the first perforated layer by fixing means to prevent the flow of gas to and from the container and wherein the gas tight layer is moved from the first position when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure such that gas may flow through perforations in the first perforated layer, through the enclosed volume and through perforations in the second perforated layer.

Alternatively, the gas tight layer comprises a fluid material of suitable viscosity such that when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure, the fluid is moved from a position where it prevents flow of gas through the first and second perforated layers to one where it allows gas to flow.

Preferably, the fluid is applied in situ between the first layer and the second layer and to ensure that the area of the package in which the fluid is present is left unsealed when a heat-seal is applied to the container. Preferably, the fluid remains filling the void where the first layer and the second layer are not sealed to create a channel for gas from the container to vent gas when a higher gas pressure exists in the container than is present outside the container.

The gas will pass through and out of the pack by forcing the oil away from the top of the pack when venting. The oil will then move back to fill the opening when the coffee has stopped venting.

Preferably, the container is a soft packet. Optionally, the container is made at least h part from rigid material

Optionally, the container is made at least in part from flexible material.

Preferably, the first perforated layer is integrally formed with the wall of the cavity

Preferably, the foil is aluminium foil.

Preferably, the outside layer printable material may be selected from one of the following materials oriented polypropylene (OPP), cast polypropylene (CPP), oriented polyamide (OPA), polyethylene (PE) or polyethyleneterephthalate (PET) Preferably, the first perforated layer is integrally formed with the wall of the cavity.

Preferably, the gas tight layer comprises a filmic thermoplastic.

Preferably, the filmic thermoplastic is made from polyethylene.

Optionally, the gas tight layer is substantially circular.

Optionally, the fixing means is a sealant.

Preferably, the fixing means is a liquid. Advantageously, a liquid fixing means of suitable peel strength and viscosity affects the seal and release of the gas tight layer from the first perforated layer by movement of the liquid into and out of contact with the gas tight layer and the first perforated layer.

Preferably, the fixing means is a mineral oil.

Preferably, the perforations are sized to prevent the fluid from entering the cavity.

Preferably the perforations are made using a laser. Optionally, the perforations are holes punched into the respective layers. Optionally, the perforations are cuts made in the respective layers. Brief Description of the Drawings

The present invention will now be described by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a known type of container and one way valve;

Figure 2 is a perspective view of a first embodiment of a container in accordance with the present invention;

Figure 3 is a cross sectional view along line "B" of an embodiment of a one way valve in accordance with the present invention;

Figure 4 is a cross sectional view along line "A" of an embodiment of a one way valve in accordance with the present invention;

Figure 5 is a side view similar to that shown in figure 3 but which shows the passage of excess gas through the valve; Figure 6 Is a cross sectional view similar to that shown in figure 4;

Figure 7a is a schematic diagram which shows a novel process for making a valve in accordance with the present invention, figure 7b shows the cross section of the outer second layer and figure 7c shows a cross section of an example of the finished valve;

Figure 8 is a cut-away drawing of a further embodiment of a container in accordance with the present invention;

Figure 9 is a cut-away drawing of a further embodiment of a container in accordance with the present invention; and Figure 10 is a cut-away drawing of a further embodiment of a container in

accordance with the present invention.

Detailed Description of the Drawings The present invention provides a novel type of one way degassing valve which may be integrally formed with a container or packet. In particular the present invention may be integrally formed with the type of soft packet often used for perishable commodities such as coffee. Figure 2 is a perspective view of a first embodiment of a container in accordance with the present invention. Figure 2 shows a container 11 which has a printable outer surface 13. Shown on the outer surface 13 is the one way valve 15 which extends down the front surface of the container 11 from at or near the container opening 17 towards the case 18 of the container 1.

The outside of the one-way valve 15 is shown with the second perforated layer 19 which is formed from the outer surface of the container 1 and contains a number of perforations 21. The gas tight layer is positioned below the second perforated layer 19. In this example of the present invention, the gas-tight layer 23 comprises a non- rigid strip of non-gas permeable material which acts as a seal.

Figure 3 is a cross section along the direction shown by arrow "B" in figure 2. This view of the embodiment of the present invention shows the detailed construction of the one-way valve. The cross section 31 shows the one-way valve 33, the first perforated layer 35 is positioned inside the container cavity and the second perforated layer 45 is positioned on the outer surface of the container 11. The gas tight layer 41 is positioned directly between the first perforated layer 35 and the second perforated layer 45. Perforations in the first perforated layer 37 and perforations 47 in the second perforated layer 45 extend through the respective perforated layers. Perforations 37 provide a channel through which gas may flow from the cavity 49 to the gas tight layer 41 . Perforations 47 provide a channel through which gas may flow from the enclosed volume 43 to outside the container 51.

The gas tight layer 41 is removeably fixed to the first perforated layer 35 such that the gas tight layer 41 covers the perforations 37 in the first perforated layer 35. In this example of the present invention the fixing means 39 comprises a mineral oil which provides a breakable bond which seals together the gas tight layer 41 and the first perforated layer 35. The strength of the bond is engineered to allow gas to flow from the cavity inside the container and through the one-way valve to reduce the excess high pressure resultant from a build up of gas within the cavity. In this embodiment of the present invention the first perforated layer 35 and the second perforated layer 45 of the one-way valve are formed from the outer layer 32 of the container and the inner layer 36 of the container. As show in figure 3, in the general construction of the container, the outer layer 32 and the inner layer 36 are bonded together, preferably in a lamination process. The area which forms the one- way valve of the present invention the outer layer 32 and the inner layer 36 are not bonded together leaving an enclosed volume into which the gas tight layer may be introduced. Figure 4 is a cross section along the direction shown by arrow "A" of figure 2. The first perforated layer 35 is made from low density polyethylene (LDPE); the fixing means is a mineral oil 39 which has a suitable level of adhesion to the LDPE layer 35 and the gas tight layer 41. The second perforated layer 45 comprises an outer printable layer of Polyethylene terephthalate (PET) 63 and a layer of aluminium foil 65.

Figure 5 shows a cross section of the container along line 'B' which is similar to that shown in figure 3 but which shows the presence of excess gas in the container cavity and the operation of the one-way valve. Excess gas 53 may build up inside the cavity 49 as a result of continuing chemical reactions inside the cavity 49 or as a result of the application of heat or other processes which increase the amount of gas in the cavity 49. The excess gas 53 causes the gas pressure within the cavity to increase which can cause the container to bulge or otherwise put stress on the walls of the container. Once the gas pressure reaches a predetermined level, the bond between the gas tight layer 41 and the first perforated layer 35, which has been created by the mineral oil 39 is broken and the gas tight layer 41 is lifted up from on top of the first perforated layer to create a channel or gap 55. Accordingly, gas is able to flow 57 from the cavity 49 out of the container. The gas 59 outside the chamber disperses into the atmosphere 51.

Figure 6 shows a cross section 71 at another embodiment of a one- way valve in accordance with the present invention. In this example the PET layer 73 is bonded to the aluminium foil 77 by means of an adhesive 75. The gas tight layer is described as a floating diaphragm 79 because it is supported on a layer of mineral oil 81 which seals and releaseably bonds the floating diaphragm 79 to the LDPE layer 83.

An example of a process for creating a container in accordance with the present invention will now be described with reference to figure 7. In this example of the present invention, the process 101 has been designed in two stages.

The first stage 103 relates to the creation of the outside layer of the container, part of which forms the second perforated layer. The second stage 131 relates to the process for combining together the outside layer of the container with the inside surface and the addition of the gas tight layer.

The first stage 103 comprises the reverse printing of the PET Laminate to Aluminium Foil and the creation of perforations through all layers of laminate. In this stage of the process, a reel of PET 105 and a reel of aluminium foil 109 are provided, lengths of the material are unravelled and carried along via rollers 113 to be laminated together 115 using a suitable adhesive for permanently bonding the layers together to form ply 1 123. Prior to being collected onto a reel 119, perforations 117 are made in the laminate at specifically designated positions that will form the second perforated layer and part of the cavity of the one way valve.

Figure 7b shows a cross section of the laminate 121 which comprises a PET layer 123 an adhesive bonding layer 125 and an aluminium foil layer 127 as well as perforations 129.

In the second stage 131 , ply 1 134 is combined with the diaphragm strip or gas tight layer 140 on reel 135 and with the first perforated layer LDPE 138 from reel 139. All three materials are unwound from their reels into elongated sheets to be laminated together 141 using suitable adhesives. This requires laminating ply 1 134 to the layer of LDPE 138 using an adhesive roller 141 to apply a clear/adhesive to the layers at positions outside of the area which will form the first and second perforated layers. Whilst laminating the ply 1 layer 134 to the LDPE a reel fed 135 gas tight layer

(diaphragm strip) 140 is positioned about the centres of perforations in the ply 1 layer 134. The LDPE layer 138 is perforated after it has been unwound and before the introduction of the diaphragm strip 140. The diaphragm strip 140 is immersed in mineral oil pre feed to laminate to coat one side only allowing it to adhere to the LDPE. In order to form the completed body of the container 143, the ply 1 33 layer and the LDPE layer 139 must be correctly aligned with respect to the gas tight strip 140 to ensure that the unbounded parts which form the first and second perforated layers enclose the gas tight strip 140. Figure 7c shows in cross section an example of a gas tight seal in accordance with the present invention comprising the second outer layer 121 and the first inner layer 149 with the seal arranged in an enclosed volume between them. The volume having channels into and out from the volume which are perforations in the respective layers.

The following embodiments of the present invention use a sealant fluid without a sealant strip to provide a valve in accordance with the present invention.

These examples provide a bag that has the same exit only venting characteristics but without the need for any extra application machinery on the packing line or any other consumables required. This would also mean that the product would be available in reel form and would run on any type of suitable packing line for packing coffee. Figure 8 is a drawing which is a cut-away view 161 of the layers of a container in accordance with the present invention. The figure shows a PET top web 163 a foil second web 165, a PE inner web 167 and punched holes169 which are positioned in a strip in which a fluid sealant (oil) 171 is applied. The oil 171 is applied in situ between the foil 165 and the PE 167 to ensure that the area of the package in which the oil is present is left unsealed when a heat-seal is applied to the container. The oil 171 remains filling the void where the two layers of PE are not sealed. This is then able to create a channel for gas from the container to vent gas when a higher gas pressure exists in the container than is present outside the container. The gas will pass through and out of the pack by forcing the oil away from the top of the pack when venting. The oil will then move back to fill the opening when the coffee has stopped venting.

Figure 9 shows another embodiment of the invention. The reference numerals of figure 8 have been used where corresponding features are present in figure 9. In this embodiment, no PE is removed from the finished film. The film is simply cut to create a series of vents 173 in the PE to allow air to pass through and out of the pack in a similar manner to that described in figure 8. Figure 10 shows another embodiment of the invention in which a laser is used to create perforations 175 in the PE layer. The reference numerals of figure 8 have been used where corresponding features are present in figure 10. In figure 0 both the adhesive free area and the oil applied area can be considerably smaller than that shown in figures 8 and 9. The main advantages of this version over those of figures 8 and 9 is that this version requires a much smaller adhesive free and oil applied areas. The perforations may be sized to allow gas to pass through the hole but not allow oil to pass back through the holes and into the bag itself.

This embodiment has the same principle of operation as that of figures 8 and 9 in that the oil in the channel prevents the PE from sealing to itself through the packing line. This oil will then move to allow gas to pass out of the bag when the pack is under pressure and return to its original position once the overpressure inside the container has reduced.

Advantageously, the present invention allows the creation of a container which has a one way valve. As well as the novel construction of the container and the seal, the novel process for making the container allows the addition of the one way valve to be incorporated within the process of making the container itself thereby avoiding the need to firstly create the container then insert a degassing valve which has been made in an entirely separate process. Another advantage of the present invention is that the degassing valve may be made from soft packing material such as PET and LDPE, this allows the valve to be positioned along the length of a packet allowing the excess gas to exit from the cavity in more locations. The well known, substantially rigid valves must be relatively small so that the soft package in which it is inserted can retain its softness and flexibility.

Improvements and modifications may be incorporated herein without deviating from the scope of the invention.

Claims

1. A container adapted to prevent a build-up of gas therein, the container comprising:

at least one gas tight wall which forms a cavity in which a product may be enclosed; an outside wall; and

a one way valve for allowing gas in the cavity at higher pressure than the ambient pressure outside the cavity to leave the cavity, the valve comprising:

a first perforated layer which forms part of the gas tight wall of the cavity;

a second perforated layer which forms part of the outside of the container, the first perforated layer and the second perforated layer being joined together such that an enclosed volume is formed between the first perforated layer and the second perforated layer;

a gas tight layer in a first position across the first perforated layer to prevent the flow of gas to and from the container and wherein the gas tight layer is moved from the first position when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure such that gas may flow through perforations in the first perforated layer, through the enclosed volume and through perforations in the second perforated layer.

2. A container as claimed in claim 1 wherein, the gas tight layer comprises a strip of material removeably connected in the first position across the first perforated layer by fixing means to prevent the flow of gas to and from the container and wherein the gas tight layer is moved from the first position when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure such that gas may flow through perforations in the first perforated layer, through the enclosed volume and through perforations in the second perforated layer.

3. A container as claimed in claim 1 wherein, the gas tight layer comprises a fluid material of suitable viscosity such that when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure, the fluid is moved from a position where it prevents flow of gas through the first and second perforated layers to one where it allows gas to flow.

4. A container as claimed in claim 3 wherein , the fluid is applied in situ between the first layer and the second layer and to ensure that the area of the package in which the fluid is present is left unsealed when a heat-seal is applied to the container.

5. A container as claimed in claims 3 and 4 wherein, the fluid remains filling the void where the first layer and the second layer are not sealed to create a channel for gas from the container to vent gas when a higher gas pressure exists in the container than is present outside the container.

6. A container as claimed in any preceding claim which is a soft packet.

7. A container as claimed in any preceding claim wherein, the container is made at least in part from rigid material

8. A container as claimed in any preceding claim wherein, the container is made at least in part from flexible material.

9. A container as claimed in any preceding claim wherein, the first perforated layer is integrally formed with the wall of the cavity

10. A container as claimed in any preceding claim wherein, the second perforated layer is integrally formed with the outside of the container.

1 1. A container as claimed in any preceding claim wherein, the outside of the container comprises an outer layer of printable material bonded to a layer of foil.

12. A container as claimed in claim 1 1 wherein, the foil is aluminium foil.

13. A container as claimed in any preceding claim wherein, the outside layer printable material may be selected from one of the following materials oriented polypropylene (OPP), cast polypropylene (CPP), oriented polyamide (OPA), polyethylene (PE) or polyethyleneterephthalate (PET)

14. A container as claimed in any preceding claim wherein, the gas tight layer comprises a filmic thermoplastic.

15. A container as claimed in claim 14 wherein, the filmic thermoplastic is made from polyethylene.

16; A container as claimed in claim 15 wherein, the filmic thermoplastic is made from low density polyethylene (LDPE).

17. A container as claimed in claims 1 , 2 and 6 to 16 wherein, the gas tight layer is a strip extending down one wall of the container through the enclosed volume.

18. A container as claimed in claims 1 , 2 and 6 to 16 wherein the gas tight layer is substantially circular.

19. A container as claimed in claim 2 wherein, the fixing means has a suitable peel strength such that it will move to the second position when an overpressure exists within the container.

20. A container as claimed in claim 2 and claim 19 wherein, the fixing means is an adhesive.

21. A container as claimed in claim 2 and claim 19 wherein, the fixing means is a sealant.

22. A container as claimed in claim 2 and claim 19 wherein, the fixing means is a liquid.

23. A container as claimed in claim 22 wherein, the fixing means is a mineral oil.

24. A container as claimed in any preceding claim wherein, the perforations are holes punched into the respective layers.

25. A container as claimed in any preceding claim wherein, the perforations are cuts made in the respective layers.

26. A method for making a container which has an integrated one way valve, the method comprising the steps of:

creating an outer layer of the container;

27. A method as claimed in claim 26 wherein, the step of introducing a gas tight layer further comprises introducing a fixing means into the enclosed volume either before or after the enclosed volume has been formed

28. A method as claimed in claim 26 wherein, the gas tight layer comprises a fluid material of suitable viscosity such that when the gas pressure inside the container exceeds a predetermined level with respect to the ambient pressure, the fluid is moved from a position where it prevents flow of gas through the first and second perforated layers to one where it allows gas to flow.

29. A method as claimed in claim 28 wherein, the fluid is applied in situ between the first layer and the second layer and to ensure that the area of the package in which the fluid is present is left unsealed when a heat-seal is applied to the container.

30. A method as claimed in claims 28 and 29 wherein, the fluid remains filling the void where the first layer and the second layer are not sealed to create a channel for gas from the container to vent gas when a higher gas pressure exists in the container than is present outside the container.

31. A method as claimed in claims 26 to 29 wherein, the container is made at least in part from rigid material

32. A method as claimed in claims 26 to 29 wherein, the container is made at least in part from flexible material.

33. A method as claimed in claims 26 to 32 wherein, the first perforated layer is integrally formed with the wall of the cavity

34. A method as claimed in claims 26 to 33 wherein, the second perforated layer is integrally formed with the outside of the container.

35. A method as claimed in claims 26 to 34 wherein, the outside of the container comprises an outer layer of printable material bonded to a layer of foil.

36. A method as claimed in claims 26 to 35 wherein, the foil is aluminium foil.

37. A method as claimed in claims 26 to 36 wherein, the outside layer printable material may be selected from one of the following materials oriented polypropylene (OPP), cast polypropylene (CPP), oriented polyamide (OPA), polyethylene (PE) or polyethyleneterephthalate (PET)

38. A method as claimed in claims 26 to 37 wherein, the first perforated layer is integrally formed with the wall of the cavity.

39. A method as claimed in claims 26 to 38 wherein, the gas tight layer comprises a filmic thermoplastic.

40. A method as claimed in claim 39 wherein, the filmic thermoplastic is made from polyethylene.

41. A method as claimed in claims 41 and 42 wherein, the filmic thermoplastic is made from low density polyethylene (LDPE).

42. A method as claimed in claims 26, 27 and 31 to 41 wherein, the gas tight layer is a strip extending down one wall of the container through the enclosed volume.

43. A method as claimed in claims 26, 27 and 31 to 41 , wherein the gas tight layer is substantially circular.

44. A method as claimed in claims 26 to 43, wherein the fixing means has a suitable peel strength such that it will move to the second position when an overpressure exists within the container.

45. A method as claimed in claims 26 to 44 wherein, the fixing means is an adhesive.

46. A method as claimed in claims 26 to 44, wherein the fixing means is a sealant.

47. A method as claimed in claims 26 to 46, wherein the fixing means is a liquid.

5

48. A method as claimed in claim 47 wherein, the fixing means is a mineral oil.

49. A method as claimed in claims 26 to 47, wherein, the perforations are holes punched into the respective layers.

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50. A method as claimed in claims 26 to 49, wherein, the perforations are cuts made in the respective layers.