WO2008068520A1

WO2008068520A1 - Vacuum-packing methods and apparatus

Info

Publication number: WO2008068520A1
Application number: PCT/GB2007/050588
Authority: WO
Inventors: Martin Dominic Smithson; Tien Tjiu Tan
Original assignee: 3 S's Limited
Priority date: 2006-09-27
Filing date: 2007-09-27
Publication date: 2008-06-12
Also published as: GB0619003D0

Abstract

A vacuum-packing apparatus for vacuum-packing a compressible product (1) within an airtight enclosure of flexible material, the compressible product initially being located between first and second layers (2, 3) of the flexible material, includes: compression means (5) for compressing the product to expel air therefrom; vacuum means (7) to evacuate the enclosure; and closing means for joining the layers subsequent to evacuation to close the enclosure; wherein the apparatus comprises sealing means (6) to seal off a section of flexible material during compression but before evacuation so that the amount of flexible material required to make the enclosure can be reduced.

Description

Vacuum-Packing Methods and Apparatus

This invention relates to vacuum-packing apparatus for vacuum-packing a product within an airtight enclosure formed from a flexible material and methods for achieving the same. In particular, the product may be compressible product, for example plastic waste bags, rubber gloves etc.

When packaging products, it is preferable to reduce the size of the packaged products as much as is possible, so as to maximise the number of packages that can be stored or transported for example. Furthermore, smaller packages require correspondingly less packaging material and therefore are of environmental benefit.

One technique for minimising package sizes is to package the product using a vacuum- packing technique. Here, the product concerned is located within an airtight enclosure formed from a flexible material, e.g. a plastics material, from which as much air as possible has been evacuated.

In order to further reduce the amount of air within the enclosure, when packaging a compressible product, it is possible to compress the package before and during the evacuation process. In this way, air is expelled from the product before evacuation commences. The finished package is correspondingly smaller in size than the conventional vacuum-packed package. Such a technique is known from British Patent No. GB 2375518 B.

Typically, the product to be packaged is inserted into a pocket of flexible covering material, i.e. a substantially rectangular envelope which is pre-sealed along three of the four sides. This package is then held between two trays or moulds which shape the package during evacuation. The package is compressed to remove excess air from the product and package, and then the package is evacuated and the open edge is sealed to form an airtight enclosure. Although such techniques provide very compact packages, there are some associated drawbacks. For example, the packages thus produced typically have at least one edge with a sizeable "flap" of the flexible packaging material formed by two layers of the material held together by the vacuum. The flap increases the size of the package and indicates wastage of the packaging material. In addition, the regions around the sealed joins of the enclosure may be crumpled or wrinkled as a result of the evacuation procedure. Such wrinkles detract from the appearance of the package, increase the size of the package, and indicate further wastage. Finally, as the enclosure material is primarily functional, the appearance of the package may be compromised in relation to traditionally packaged products.

It is an aim of the present invention to provide vacuum-packing apparatus and methods which substantially overcome these problems.

In accordance with a first aspect of the present invention, there is provided a vacuum- packing apparatus for vacuum-packing a compressible product within an airtight enclosure formed from first and second layers of flexible material, the compressible product initially being located between the first and second layers, the apparatus including: compression means for compressing the product to expel air therefrom; vacuum means to evacuate air from between the first and second layers; and closing means for joining the layers subsequent to evacuation to form the enclosure; wherein the apparatus comprises sealing means to seal off a section of flexible material during compression but before evacuation so that the amount of flexible material required to make the enclosure can be reduced.

In accordance with a second aspect of the present invention there is provided a method of vacuum-packing a compressible product within an airtight enclosure formed from first and second layers of flexible material, comprising the steps of: a) locating the compressible product between the first and second layers of the flexible material; b) compressing the product to expel air from the product; c) sealing off a section of the flexible material; d) evacuating air from between the first and second layers; and e) joining the first and second layers to close the enclosure.

In accordance with a third aspect of the present invention there is provided a vacuum- packing apparatus for vacuum-packing a product within an airtight enclosure of flexible material, the product initially being located between first and second layers of the flexible material, the apparatus including: a support tray for supporting the first layer, the product and the second layer; vacuum means to evacuate the region between the first and second layer; and sealing means for sealing the first and second layers to each other subsequent to evacuation to form the enclosure; wherein the apparatus comprises means for restraining portions of the first and second layers during evacuation to prevent their crumpling during evacuation.

In accordance with a fourth aspect of the present invention there is provided a method of vacuum-packing a product within an airtight enclosure formed from a flexible material, comprising the steps of: a) providing first and second layers of the flexible material and locating the product therebetween; b) restraining portions of the first and second layers to prevent their crumpling during subsequent evacuation; c) evacuating the region between the first and second layers; and d) sealing the first and second layers together subsequent to evacuation to form the enclosure.

In accordance with a fifth aspect of the present invention there is provided a method of vacuum-packing a product including a container formed from a relatively rigid material within an airtight enclosure formed from a flexible material, comprising the steps of: a) providing a sheet of container material; b) forming a container for the product from the container material and locating the product within the container; c) providing first and second layers of the flexible material; d) locating the container between said first and second layers; e) compressing the layers, product and container to expel air therefrom; f) evacuating the region between the first and second layers; and g) sealing the first and second layers together subsequent to evacuation to form the enclosure. Further features of the present invention are set out in the accompanying claims.

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

Figure 1 shows a product loaded into a pre-sealed pocket of flexible covering material in a first embodiment of the present invention;

Figure 2 shows compression and sealing apparatus of the first embodiment;

Figure 3 shows the apparatus of Fig. 2 used for sealing a package;

Figure 4 shows vacuum-packing apparatus used in the first embodiment;

Figure 5 shows vacuum-packing apparatus used in a second embodiment of the present invention;

Figure 6a shows a blank for constructing a display sheet in a third embodiment of the present invention;

Figure 6b shows an alternative blank to that of Fig. 6a for use in the third embodiment;

Figure 7 shows apparatus for construction of the package using the display of Figs. 6a or

6b;

Figure 8 shows apparatus for sealing the package in the third embodiment;

Figure 9 shows a perspective view of a further embodiment of a vacuum packing apparatus; and

Figure 10 shows a front view of the vacuum packing apparatus of Fig. 9.

A first embodiment of the present invention is shown in Figs 1 to 4, which enables the amount of flexible covering material used in the vacuum-packing process to be reduced.

As shown in Fig. 1, a compressible product 1 is initially located between first and second substantially rectangular layers 2, 3 of the flexible covering material. In the embodiment shown, the layers 2, 3 are sealed along three edges, to form a pocket 4 of the material, with one edge unsealed to enable the product to be inserted therethrough. Alternatively, a sheet of material may be folded over itself (known as a "J-fold") and then sealed along two adjacent, orthogonal sides. This forms an alternative type of pocket, with one open end, two sealed edges, and a fourth side that is formed by the fold-line of the material. Here again, the product may be inserted into the pocket through the open end. Alternatively, the product may be placed on the sheet which is then folded over the product and the two sides sealed as before. A further alternative is that the product may be placed between two unjoined sheets of material, and the required sealing is carried out during a subsequent process as described below.

Fig. 1 shows an embodiment in which the product 1 is inserted into a pocket 4 which is pre-sealed on three sides to form a package "bundle". The width of the pocket 4 is necessarily greater than the width of the product 1 so to allow easy insertion, so that there is a flap of excess material included at each side of the package. One of these flaps of excess material is designated as a section of width "a" on Fig. 1. The two closed rear corners of the pocket, i.e. the two corners at the opposite end to the open side of the pocket are pre-sealed and trimmed to remove excess material prior to insertion of the product 1. Alternatively, these corners may be sealed and trimmed during the subsequent compression procedure.

Fig. 2 shows apparatus for carrying out compression and trimming of the package. The package is compressed by the downward movement of a pressure plate 5 onto the package. This acts to expel excess air from the bundle. Due to the compression, the amount of excess material, i.e. width "a" actually increases, as less material is needed to cover the compressed, and therefore smaller, product. In order to gather as much excess material on one side of the package as possible, the product is moved within and relative to the pocket of material. This may be done, for example, by means of a pusher arm (not shown) which pushes the product to one side of the pocket. The product may additionally be pushed toward the rear of the pocket, for example by a further pusher arm, so that the product is moved to a corner of the pocket. This pushing of the product may be carried out prior to, or during, compression of the package.

While the package is under compression, side sealing means 6 is moved to engage the package so that it can seal off the flap of excess material. Side seal 6 typically uses heat sealing to join the first 2 and second 3 layers of flexible material together as close as possible to the product, so that the amount of excess material sealed off is maximised. The side seal 6 also trims the excess material from the package. The trimmed off material may then be recycled as appropriate.

After sealing, the side seal 6 is disengaged and the package is rotated 90 degrees to the position shown in Fig. 3. The side seal is then re-engaged to seal the front of the pocket 4, through which the product 1 was loaded. The sealed-off excess material is again trimmed.

In order to remove further excess material, an open corner of the package may be also sealed and trimmed. This is achieved by disengaging the side seal 6, rotating the package 45 degrees and re-engaging the side seal 6. If the two closed corners were not sealed and trimmed before insertion of the product 1 into the pocket 4, as described previously, they may be sealed and trimmed at this stage. This leaves one corner unsealed to enable evacuation of the package, as will be described below.

Once the excess material has been trimmed, the package is evacuated, using apparatus as shown in Fig. 4. The orientation of the package is controlled so that the remaining unsealed corner is available. A suction tube 7 is inserted into the package, and the air within is removed. The suction tube 7 is then removed and the package is sealed to form an airtight enclosure, using a seal clamp 8 and vacuum clamp 9 to insure that the vacuum is maintained during withdrawal of the suction tube 7 and subsequent sealing. The sealing is carried out by a heat seal 10. The operation of sealing is conducted as follows. Firstly the enclosure is clamped using vacuum clamp 9 and air is evacuated form the enclosure using the suction tube 7. Next the suction tube 7 removed from the enclosure and seal clamp 8 is actuated to hold the enclosure during sealing. The enclosure is then sealed using the heat seal 10 and the clamps are released. The package produced uses a minimum of covering material, which both reduces the size of the package and reduces the raw materials used. All of the excess material trimmed off can be recycled for future use.

Although the embodiment described above uses a pre-formed pocket of covering material, as mentioned earlier this is not essential. When using two separate sheets of material, the method must be modified slightly. For example, the product will not be pushed relative to the sheets, as there is no sealed side to push up against. Instead, the product will be compressed, thus creating excess material, which is then sealed off and trimmed as above. Sealing and trimming is performed on each side, to form the enclosure.

A second embodiment of the invention is shown in Fig. 5. With this embodiment, crumpling at the edges of the package covering, which usually occurs during the evacuation stage, is prevented.

The product 1 to be packaged is initially located between first and second layers 2, 3 of the flexible covering material, and this bundle is supported on a substantially rectangular support tray 11. The first and second layers 2, 3 may be provided in several ways. For example, the material may be pre-formed as a pocket, which would be substantially rectangular and sealed along three of the four edges, so that the fourth edge is left open. The product can then be inserted into the pocket, so that it lies between the first and second layers of material. Alternatively, a sheet of material may be folded over itself (known as a "J-fold") and then sealed along two adjacent, orthogonal sides. This forms an alternative type of pocket, with one open end, two sealed edges, and a fourth side that is formed by the fold-line of the material. Here again, the product may be inserted into the pocket through the open end. Alternatively, the product may be placed on the sheet which is then folded over the product and the two sides sealed as before. A further alternative is that the product may be placed between two unjoined sheets of material, and the required sealing is carried out during the vacuum-packing process as described below.

Whichever method is used to provide a package bundle with the product located between two layers of flexible material, there will necessarily be excess material produced on at least one side of the product. In Fig. 5 for example, the product is shown as being preloaded into a pocket of material. The size of the pocket has to be large enough so that the product may be inserted easily, and so excess material is left at the sides of the product. Furthermore, if the product is compressed prior to evacuation, excess material will also be created as the overall size of the package decreases under compression.

The support tray 11 as shown has upwardly-extending sidewalls 12 on three sides thereof (the sidewall on the rear side is not visible in Fig. 5). The width of the support tray 11 is selected so as to fit the width of the bundle quite snugly, so that the excess material projects over the top surfaces of the sidewalls 12. An upper tray member 13 is also provided, which comprises downwardly-extending sidewalls 14 substantially the same width apart as for the support tray 11. The upper tray 13 is moveable vertically relative to the support tray 11 , as will be described below.

A pressure plate 5 is located within the upper tray 13 and movable relative thereto, which may be used to compress the bundle in preparation for evacuation as for the previous embodiment.

Fig. 5 shows the apparatus when the package is formed by a pocket of flexible material, which is pre-sealed on three sides. For other configurations, for example when two individual sheets of material are used, the sidewalls of the support or upper tray may include sealing means, for example heat-sealing means.

In use, the upper tray 13 is moved vertically away from the support tray 11 to allow loading of the bundle into the support tray 11. The sidewalls 12 of the support tray 11 act to mould the package bundle to ensure that it is neatly arranged into the desired shape. Regions of excess material project over the sidewalls 12. The upper tray 13 is then moved toward the support tray 11 so that the top surfaces of the support tray sidewalls 12 and the lower surfaces of the upper tray sidewalls 14 are brought into abutment. These upper and lower surfaces act as gripping surfaces 15 to restrain the excess material of the package therebetween. The sidewalls 14 of the upper tray act to mould the package in a similar way to the support tray sidewalls 12.

The pressure plate 5 is then lowered to compress the package, to expel air from the package and product. The pressure plate 5 acts to compress the package throughout the subsequent evacuation stage.

If the package is formed from a pocket with three pre-sealed edges, then the evacuation stage may commence. Otherwise, any free edges of the package are first sealed, for example by use of heat-sealing means provided at the upper or support tray sidewalls 14, 12.

The package is evacuated as in the previous embodiment, i.e. by insertion of an suction tube into the package, removing air from the package, and then sealing the package in an airtight manner, e.g. by heat sealing. During evacuation, the excess material is restrained between the gripping surfaces of the upper and support tray sidewalls 14, 12. This helps to prevent wrinkling or crumpling of the material during evacuation, which improves the appearance of the finished package, and, because the covering material is substantially flat at the sides, reduces the width of the finished package.

Fig. 5 shows that the upper and support trays 13, 11 have substantially equal length sidewalls 14, 12. This is useful for the situation where the excess material is located proximate the middle of the package. However, there may be situations in which the excess material is located at a different position, for example at an edge of the package. This may occur when the first and second layers 2, 3 of flexible covering material are provided by two separate sheets of the material. In this case, the product may be placed on the bottom sheet, with the upper sheet then placed on top of the product. The sheets would meet, and be joined at, the lower edges of the product. For such configurations, alternative designs of trays may be used. With the above example, the support tray may include little or no sidewall, while the upper tray would include an extended sidewall, so that the gripping portions would still abut in the region of the excess material.

A third embodiment of the present invention is shown in Figs. 6a to 8. In this embodiment, a relatively rigid display sheet is included in the package, between the product and the outer covering. The display sheet, which may for example comprise cardboard or plastics material, forms a container or box around the product, and may be printed to provide product information which is readable through the covering. The display sheet may also be used to help maintain the correct shape of package. If the product comprises discrete articles such as bags or rubber gloves for example, the display sheet may be provided with an aperture to enable individual articles to be dispensed from the package without damaging its structural integrity.

Production of a package including such a display sheet involves a two-stage process, firstly the display sheet is formed, and secondly the package with the display sheet is vacuum-packed.

Initially, a display sheet blank 16 is constructed. The blank 16 may be formed from one sheet, as shown in Fig. 6a, or from two sheets, as shown in Fig. 6b. In both cases, the blank 16 is folded to create edges, so that the blank 16 may be formed into a box-shape. As shown, the blank includes both a dispensing hole 17 for dispensing of the product, and a suction hole 18 to enable evacuation of the interior of the package in the second stage. As shown in more detail in Fig. 7, the product 1 is placed inside the blank 16 (here the two-part blank is shown), and the blank 16 is pressed and the corresponding edges sealed together to form a closed box around the product 1. The sealing may be achieved using adhesive tape applied by adhesive tape units 20 as shown, or alternatively heat-sealing for example.

The second stage commences by placing the box between first and second layers of flexible covering material to form a "bundle". The layers may be provided in several ways. For example, the material may be pre-formed as a pocket, which would be substantially rectangular and sealed along three of the four edges, so that the fourth edge is left open. The box can then be inserted into the pocket, so that it lies between the first and second layers of material. Alternatively, a sheet of material may be folded over itself (known as a "J-fold") and then sealed along two adjacent, orthogonal sides. This forms an alternative type of pocket, with one open end, two sealed edges, and a fourth side that is formed by the fold-line of the material. Here again, the box is inserted into the pocket through the open end. Alternatively, the product may be placed on the sheet which is then folded over the box and the two sides sealed as before. A further alternative, and the preferred arrangement for this embodiment, is that the box may be placed between two unjoined sheets of material, and the required sealing is carried out during the vacuum- packing process as described below. Fig. 8 shows apparatus suitable for vacuum packing the box, where the layers are provided as two separate sheets. A support tray 11 supports the first sheet (omitted for clarity), the box and the second sheet (omitted for clarity). The support tray 11 includes vertically-extending sidewall 12 along one edge, against which the package is placed. An upper tray 13 is provided above and in alignment with the support tray 11, and is vertically moveable relative to the support tray 11. The upper tray 13 includes a sidewall 14 that extends downwardly, on the opposite side of the package to the support tray sidewall 12. The support tray and upper tray sidewalls 12, 14 include heat sealing means 19 at their horizontal surfaces.

A pressure plate (not shown) is located within the upper tray 13 and movable relative thereto, which may be used to compress the bundle in preparation for evacuation as for the previous embodiments.

In use, the upper tray 13 is moved vertically away from the support tray 11 to allow loading of the bundle into the support tray 11. The sidewall 12 of the support tray 11 acts to align the package bundle to ensure that it is neatly arranged into the desired shape. The flexible material sheets extend both laterally on both sides of the bundle, i.e. both over the support tray sidewall 12 and the opposite side. The upper tray 13 is then moved toward the support tray 11 so that the horizontal surfaces of the support tray and upper tray sidewalls 12, 14 are brought into abutment with the upper tray 13 and support tray 11 respectively. The sidewall 14 of the upper tray acts to align the package in a similar way to the support tray sidewall 12.

The pressure plate is then lowered to compress the package, to expel air from the package and product. The pressure plate acts to compress the package throughout the subsequent evacuation stage.

The lateral free edges of the first and second sheets are then heat-sealed and trimmed by the heat-sealing means 19 disposed in the sidewalls 12, 14. The rear edge of the package is also sealed and trimmed by any suitable means (not shown), e.g. also by heat-sealing.

The package is evacuated as in the previous embodiments, i.e. by insertion of a suction tube into the package, removing air from the package via the suction hole in the display sheet, and then sealing the package in an airtight manner, e.g. by heat-sealing.

With this apparatus, a package is formed where the joins between the first and second layers of flexible material are located at the corners of the package, rather than at the middle of the sides. This helps to maintain a clean box-shape to the package, and enables the display sheet to be more easily read through the covering.

Although the apparatus shown permits substantially cuboid packages to be formed, similar apparatus may be used to form packages of other shapes. It is possible for example to form packages in the form of a triangular prism. This may be achieved simply by using a pressure plate of different form, for example using a inverted V-shape pressure plate. Alternatively, two planar pressure plates could be used to apply pressure to the top of the package in two, respective directions. In these cases, the support tray used would include little or no sidewall, while the upper tray could include two oppositely-opposed sidewalls of equal length, with heat-sealing means disposed at the horizontal surface of each sidewall. This arrangement would act to seal the package at the two lower side edges.

Turning now to Figs. 9 and 10, these show a vacuum packing apparatus 30 according to a further embodiment of the present invention. The apparatus 30 comprises two opposing compression plates 32, 34 and an associated clamping and sealing mechanism 36

The product (not shown) to be packaged is initially located between first and second layers of the flexible covering material, and this bundle is supported on a horizontal surface, such as a conveyor belt 38. The first and second layers may be provided in several ways. For example, the material may be pre-formed as a pocket, which would be substantially rectangular and sealed along three of the four edges, so that the fourth edge is left open. The product can then be inserted into the pocket, so that it lies between the first and second layers of material. Alternatively, a sheet of material may be folded over itself (known as a "J- fold") and then sealed along two adjacent, orthogonal sides. This forms an alternative type of pocket, with one open end, two sealed edges, and a fourth side that is formed by the fold-line of the material. Here again, the product may be inserted into the pocket through the open end. Alternatively, the product may be placed on the sheet which is then folded over the product and the two sides sealed as before. A further alternative is that the product may be placed between two unjoined sheets of material, and the required sealing is carried out as described above in relation to the other embodiments of the invention.

The bundle of the product and the sheet material is closed on three sides (either by folding or sealing) and has one open side. The bundle is placed on the horizontal surface between the opposed compression plates 32, 34, or placed on the conveyor belt 38 and moved into position between the opposed compression plates 32, 34, such that the open side projects upwards.

The compression plates 32, 34 comprise vertical, opposing side walls 32a, 34a which are moveable towards and away from one another to compress the bundle and force air out of the product and the enclosure. At the upper end of each compression plate 32, 34 there is provided clamping and sealing means 36. The clamping and sealing means 36 may be provided adjacent the upper end of the compression plates 32, 34, or they may be integrated within the compression plates 32, 34. Also provided at the upper end of the compression plates 32, 34 is air evacuation means (not shown).

When the bundle is located between the compression plates 32, 34, they are actuated in order to compress the bundle and force air out of the product and the enclosure. Next, the clamping and sealing means 36 are actuated. The clamping and sealing means take the same form as described in relation to Fig. 4.

The compression plates 32, 34 are mounted on support posts, such that they may be adjusted to operate in conjunction with packages of different sizes. The compression plates 32, 34 may be adjusted vertically along the length of their respective support posts.

The above-described embodiments are exemplary only, and many other alternatives will be apparent to those skilled in the art, within the scope of the accompanying claims.

Claims

1. Vacuum-packing apparatus for vacuum-packing a compressible product within an airtight enclosure formed from first and second layers of flexible material, the compressible product initially being located between the first and second layers, the apparatus including: compression means for compressing the product to expel air therefrom; vacuum means to evacuate air from between the first and second layers; and closing means for joining the layers subsequent to evacuation to form the enclosure; wherein the apparatus comprises sealing means to seal off a section of flexible material during compression but before evacuation so that the amount of flexible material required to make the enclosure can be reduced.

2. Apparatus according to Claim 1, comprising cutting means for removing the sealed off section.

3. Apparatus according to either of Claims 1 and 2, comprises means for adjusting the position of the compressible product within and relative to the layers prior to evacuation.

4. Apparatus according to Claim 3, wherein the means for adjusting the position of the compressible product moves the compressible product in two substantially orthogonal directions relative to the pocket.

5. Apparatus according to either of Claims 3 and 4, wherein the means for adjusting the position of the compressible product comprises a pushing arm.

6. Apparatus according to any preceding claim, comprising means for rotating the pocket within the horizontal plane.

7. Apparatus substantially as herein described with reference to Figs. 1 to 4 of the accompanying drawings.

8. A method of vacuum-packing a compressible product within an airtight enclosure formed from first and second layers of flexible material, comprising the steps of: a) locating the compressible product between the first and second layers of the flexible material; b) compressing the product to expel air from the product; c) sealing off a section of the flexible material; d) evacuating air from between the first and second layers; and e) joining the first and second layers to close the enclosure.

9. A method according to Claim 8, comprising the step of removing the section of flexible material.

10. A method according to either of Claims 8 and 9, comprising the step of adjusting the position of the compressible product within and relative to the layers.

11. A method according to any of Claims 8 to 10, comprising the step of rotating the enclosure within the horizontal plane to enable selected areas of the enclosure to be sealed by the sealing means.

12. A method according to any of Claims 8 to 11, wherein the layers are substantially rectangular and pre-sealed along two adjacent edges.

13. A method according to any of Claims 8 to 11, wherein the layers are substantially rectangular and pre-sealed along three edges.

14. A method substantially as herein described with reference to Figs. 1 to 4 of the accompanying drawings.

15. Vacuum-packing apparatus for vacuum-packing a product within an airtight enclosure of flexible material, the product initially being located between first and second layers of the flexible material, the apparatus including: a support tray for supporting the first layer, the product and the second layer; vacuum means to evacuate the region between the first and second layer; and sealing means for sealing the first and second layers to each other subsequent to evacuation to form the enclosure; wherein the apparatus comprises means for restraining portions of the first and second layers during evacuation to prevent their crumpling during evacuation.

16. Apparatus according to Claim 15, wherein the restraining means comprises an upper member which is movable relative to the support tray.

17. Apparatus according to Claim 16, wherein each of the support tray and upper member comprises respective gripping surfaces which may be brought into and out of abutment by said relative motion, such that in use the restrained portions of the first and second layers are squeezed between the respective gripping surfaces.

18. Apparatus according to Claim 17, wherein the upper member comprises an upper tray, and wherein at least one of the support tray and upper tray comprises first and second vertically-extending sidewalls located on opposite sides of the respective tray, such that the distal ends of the respective sidewalls provide the respective gripping surfaces.

19. Apparatus according to any of Claims 15 to 18, comprising compression means for compressing the product between the first and second layers to expel air from the product prior to evacuation.

20. Apparatus according to Claim 19, wherein the compression means comprises a pressure plate.

21. Apparatus according to Claim 20 when dependent on Claim 18, wherein the pressure plate is housed within the upper tray.

22. Apparatus according to any of Claims 19 to 21, comprising additional sealing means for sealing together the first and second layers along selected sealing lines during compression.

23. Apparatus according to Claim 22, wherein the additional sealing means are housed in the or one of the trays.

24. Apparatus substantially as herein described with reference to Fig. 5 of the accompanying drawings.

25. A method of vacuum-packing a product within an airtight enclosure formed from a flexible material, comprising the steps of: a) providing first and second layers of the flexible material and locating the product therebetween; b) restraining portions of the first and second layers to prevent their crumpling during subsequent evacuation; c) evacuating the region between the first and second layers; and d) sealing the first and second layers together subsequent to evacuation to form the enclosure.

26. A method according to Claim 25, wherein step b) includes squeezing said portions between upper and lower relatively movable members.

27. A method according to either of Claims 25 and 26, further comprising the step of compressing the product prior to performing step c).

28. A method according to any of Claims 25 to 27, including an initial step of providing the first and second layers in the form of a substantially rectangular pocket with one open end.

29. A method according to Claim 28, wherein the pocket is provided by pre-sealing first and second sheets of the flexible material together along three sealing lines.

30. A method according to Claim 28, wherein the pocket is provided by folding over a single sheet of flexible material to form the first and second layer and sealing along two sealing lines.

31. A method according to any of Claims 25 to 27, including the step of sealing the first and second layers together along four sealing lines.

32. A method substantially as herein described with reference to Fig. 5 of the accompanying drawings.

33. A method of vacuum-packing a product including a container formed from a relatively rigid material within an airtight enclosure formed from a flexible material, comprising the steps of: a) providing a sheet of container material; b) forming a container for the product from the container material and locating the product within the container; c) providing first and second layers of the flexible material; d) locating the container between said first and second layers; e) compressing the layers, product and container to expel air therefrom; f) evacuating the region between the first and second layers; and g) sealing the first and second layers together subsequent to evacuation to form the enclosure.

34. A method according to Claim 33, wherein the container is formed by folding the sheet and joining free edges of the sheet together.

35. A method according to either of Claims 33 and 34, further comprising the steps of providing an additional sheet of container material and forming the container by joining free edges of the first and second sheets.

36. A method according to any of Claims 33 to 35, comprising the step of providing a dispensing aperture in the container material.

37. A method according to any of Claims 33 to 36, including the initial step of providing the first and second layers in the form of a substantially rectangular pocket with one open end.

38. A method according to Claim 37, wherein the pocket is provided by pre-sealing first and second sheets of the flexible material together along three sealing lines.

39. A method according to Claim 37, wherein the pocket is provided by folding over a single sheet of flexible material to form the first and second layer and sealing along two sealing lines.

40. A method according to any of Claims 33 to 36, including the step of sealing the first and second layers together along four sealing lines.

41. A method according to any of Claims 33 to 40, wherein step f) includes initially restraining portions of the first and second layers to prevent their crumpling during subsequent evacuation.

42. A method according to Claim 41, wherein the restrained portions are adjacent to edges of the container.

43. A method according to any of Claims 33 to 42, wherein step e) includes applying pressure via a pressure plate.

44. A method according to Claim 43, wherein the pressure plate is planar.

45. A method according to Claim 43, wherein the pressure plate is non-planar.

46. A method according to Claim 43, wherein step e) includes applying pressure via an additional pressure plate.

47. A method substantially as herein described with reference to Figs. 6a to 8 of the accompanying drawings.