WO2007091004A1

WO2007091004A1 - Foldable container

Info

Publication number: WO2007091004A1
Application number: PCT/GB2006/004408
Authority: WO
Inventors: Stephen King
Original assignee: Alexir Packaging Limited
Priority date: 2006-02-09
Filing date: 2006-11-24
Publication date: 2007-08-16
Also published as: ATE497469T1; GB0602532D0; EP1981766B1; PL1981766T3; EP1981766A1; DK1981766T3; ES2359582T3; DE602006019985D1

Abstract

The object of this invention is to provide a foldable container (1) which is sealed against spillage of liquid contents while also being gas restrictive. The container (1) is provided with a lid (17) which can be easily sealed to the container and thereby resist the leaking of the contents and to prevent flow of air from or into the container.

Description

Foldable Container

The invention relates to a container suitable for carrying various solid or liquid items including food and drinks. In particular, the invention relates to a container which can be conveniently formed from a flat pack into a three dimensional container.

Similar containers are well known, but suffer from the disadvantage that they are not sufficiently gas restrictive in construction to enable gas flushing and are unable to retain gas at a given level within the container which is important in order to keep curtain food-stuffs fresh for a given period of time, for example several days.

Other known containers use adhesive in attempt to seal the container but this does not provide the gas barrier required and is more difficult to recycle.

The object of this invention is to provide a foldable container which is sealed against spillage of liquid contents while also being gas restrictive. The container is provided with a lid which can be easily sealed to the container and thereby resist the leaking of the contents and to prevent flow of gas from or into the container. Also, the container can be used for deep freezing, chilling, microwaving or conventional oven cooking its contents.

Accordingly this invention provides a heat-sealable container formed from a one-piece foldable blank, the blank having a plurality of triangular folding faces which form the corners of the container.

Preferably, the corners of the container comprise two or more layers when folded. Preferably, the container further comprises a lid.

More preferably the lid comprises a transparent laminate film portion framed by a plastic coated cardboard material.

Preferably, the blank and/or lid comprise a cardboard coated with a plastic material such as Polyethylene (PE); Polypropylene (PP); or polyethylene terephthalate (PET).

Preferably, the blank and/or lid have a plastic coating of thickness between 30 and 60 microns. This can be increased as required.

More preferably, the blank and/or lid have a plastic coating of thickness 40 microns.

Preferably, the blank comprises at least one flange extending around its perimeter.

An outer perimeter flange provides a surface to which a lid can be attached to seal the container.

More preferably the at least one flange is of width between 1 and 5mm.

Still more preferably, the at least one flange is of width 2mm.

A narrow flange allows greater pressure per unit force to be applied to the lid-flange surface when the lid is sealed and so providing a tighter seal. Preferably, the outer perimeter flange comprises at least one split at the corner of the container.

More preferably, the or each split is approximately half the width of the flange.

A split at the comers of the perimeter flange allows the flange to "bend" around the corners of the container without the flange splitting. The plastic coating of the flange stretches around the corner to provide improved strength.

In another aspect, the present invention provides a method of forming a container from a plastic coated foldable blank comprising the steps of: punching out the foldable blank; guiding the foldable blank to fold corners directing heat at the corners of the foldable blank to melt the plastic coating and seal the container.

Preferably, the method of forming the container further comprises the step of heat sealing a lid to the container.

Optionally, the method of forming the container further comprises the step of passing gas through the container.

The webs are heat sealed so as to prevent leakage of liquid of gaseous contents through the corner seams.

Optionally, the tray also uses a separate single use lid which can easily be sealed to the tray further preventing leakage. In use, heat is applied to the surface of the material to effect sealing. The heat passes through the board and slightly melts the plastic layer on the inner surface. In addition, jets of hot air are directed over the surface to partially melt the surface causing the plastic to mould into a single solid state. When the material is folded the two melted inner surfaces stick together providing an air-tight seal.

A preferred embodiment of the invention is illustrated in the accompanying drawings wherein:

Figure 1 shows a plan view of the container of the present invention before the container is folded and sealed; and

Figure 2 shows a plan view of a lid which is sealed to the container of Figure 1.

As can be seen in the Figure 1, the blank of the container 1 has 90 degree rotational symmetry and comprises a base 3 and four trapezoidal side faces 5a, 5b, 5c, and 5d. The container 1 is made of cardboard coated on both sides with polyethylene terephthalate (PET). Molten PET is extruded onto the cardboard blank and settles to form a uniform coating of thickness of minimum of 40 microns. Opposing faces 5a and 5c are of equal dimensions with an outer side of length 1451.12mm, an inner side of length 114mm and a depth of 44.5mm. Opposing faces 5b and 5d are of equal dimensions with an outer side of length 188.29mm, an inner side of length 158mm and a depth of 45mm. Between each side face 5a-d are triangular folding faces 7 and 9. A 2mm "tram line" flange 11 extends along the outer side of each side face 5a-c. The flange 11 extends along to folding face 9 and forms "hook" flange 13 adjacent folding face 7. There is a split 15 in "tram line" flange 11 which runs transverse to the flange 11 between the trapezoidal face 5a-d and the triangular folding face 9. The split 15 is approximately half of the width of the flange 11. It may however be less than half the width.

As shown in Figure 2, a lid 17 comprises a frame 19 of cardboard coated with PET. The lid 17 may alternatively be made entirely from a polyester film or similar film. The frame 19 further comprises an insert 21 for labeling purposes. The frame 19 surrounds a polyester based transparent laminate film 23. The lid may also comprise a tab 25 to enable easier removal of the lid 17 from the container 1. The insert 21 can be produced in a different size, placed in a different position or removed altogether.

In use, to form the container 1, the blank is punched out vertically and a guide is used to fold the corners. Triangular folding faces 7 and 9 are pinched together and folding face 9 is pressed to the underside of the trapezoidal side face. The splits 15 in the tram line flange 11 allows the flange 11 to bend around each corner of the container, without the flange splitting because the PET layer stretches. The "hook" flange 13 meets flange 11 at the edge of each trapezoidal face 5a-d to form a double thickness seal. Hot air at a temperature of approximately 250⁰C is directed first at the webbed corners 7,9 of the container 1 from the inside and then from the outside of the container 1 to melt the PET layer and seal the container 1. The double thickness of the container 1 at the corners 7, 9 prevent "pin holing" and air entering the container after sealing.

The tram line flange 11 is now generally parallel to the base 3 of the container 1 to allow the lid 17 to be accurately placed on top. Hot air is then applied. The temperature of the air ranges from 15O⁰C to 27O⁰C depending on the lid material, the seal or opening required and the final application of the product. The contents of the tray may be gassed prior to sealing with the lid 17, depending on the shelf life of the contents of the container 1. If gassing is required multiple nozzles of gas are directed into the container 1 before sealing. Using a combination of heat, profiled tooling, and pressure, the lid 17 is secured to the tray using the same principle as used in sealing the webbed corners. The lid 17 is welded to the container 1 and an air tight seal is formed by the melting of the PET layer of the container 1 and the lid 17. A tight seal is formed by the narrow tram line flange 11 because of the pressure applied thereto, but the lid 17 is still peelable from the container 1.

The above described embodiment has been given by way of example only, and the skilled reader will naturally appreciate that many variations could be made thereto without departing from the scope of the present invention.

Claims

1. A heat-sealable container formed from a one-piece foldable blank, the blank having a plurality of triangular folding faces which form the corners of the container.

2. A container according to claim 1, wherein the corners of the container comprise two or more layers when folded.

3. A container according to claim 1 or claim 2 further comprising a lid.

4. A container according to claim 3, wherein the lid comprises a transparent laminate film portion framed by a plastic coated cardboard material.

5. A container according to any one of claims 1 to 4, wherein the blank comprises a cardboard coated with a plastic material such as Polyethylene (PE) Polypropylene (PP) or polyethylene terephthalate (PET).

6. A container according to claim 5, wherein the blank has a plastic coating of thickness between 30 and 60 microns.

7. A container according to claim 6, wherein the blank has a plastic coating of thickness 40 microns.

8. A container according to any preceding claim, comprising at least one flange extending around its perimeter.

9. A container according to claim 8, wherein the or each flange provides a surface to which a lid can be attached to seal the container.

10. A container according to claim 8 or claim 9, wherein the or each flange has a width between lmm and 5mm.

11. A container according to claim 10, wherein the or each flange has a width 2mm.

12. A container according to any one of claims 8 to 11, wherein the or each flange comprises at least one split at the corner of the container.

13. A container according to claim 12, wherein the or each split is half the width of the flange.

14. A method of forming a container from a plastic coated foldable blank comprising the steps of: punching out the foldable blank; guiding the foldable blank to fold corners directing heat at the corners of the foldable blank to melt the plastic coating and seal the container.

15. A method according to claim 14, comprising the step of heat sealing a lid to the container.

16. A method according to claim 14 or claim 15, further comprising the step of passing gas through the container.

17. A container as substantially herein described and referred to in the accompanying figures.

18. A method as substantially hereinbefore described as referred to in the accompanying figures.