GB2194515A - Composite containers - Google Patents

Abstract

A composite container comprises an inner plastics material container 10 and an outer case 24 of cardboard material. The outer case 24 is sealed by means of a lid 20 so as to trap the inner container 10 in the outer case 24. The outer case body 24 and lid 20 are of plastics coated cardboard to facilitate sealing of same together by bringing the plastic coated faces of the body and lid together where sealing is effected. The invention has particular application in supporting inner containers which are flimsy and not in themselves self-supporting. For use in a microwave oven, a layer of receptor material may be located between the bases of the container 10 and case 24. <IMAGE>

Description

SPECIFICATION Improvements relating to composite containers This invention relates to composite containers being containers of the type comprising an inner container for holding the container contents, and an outer case in which the inner container is contained.

The inner container is formed of plastics material, and may be formed by any suitable process such as thermoforming, injection moulding or the like and it may be rigid or flexible. The invention has particular application when the inner container is of a flimsy, non-self-supporting nature, the support for the inner container being provided by the outer case. The inner container comprises a body portion defined by a wall or walls and a base and in the widest aspect of the invention, the container may or may not have any top edge formation such as a flange or rim, and the container may or may not have its own cover.

The outer case comprises any suitable material, but typically will be cardboard or cardboard like in nature, being cut and creased to form a protective shell for the inner container on the one hand, and on the other hand serving as a means to carry advertising or other material, suitably applied thereto by printing or the like. The outer case comprises essentially two parts namely a lid portion and a body portion.

Such containers are suitable for containing a variety of foodstuffs for example frozen dinners, pies and the like and to this end such containers may be relatively flat articles and of relatively shallow depth, but it is also possible to provide composite containers of the type to which the invention relates for the holding of other foodstuffs and indeed for holding liquids, although in such case the top of the inner container must be sealed.

Composite containers of the type to which the invention relates are known, and in one specific form of known composite container, the inner container is provided with an outwardly extending flange at the top of the wall thereof, and this flange is trapped between a flange on the body portion of the outer case and a peripheral rim of the lid portion. The said peripheral rim, inner container flange and body portion flange are sandwiched and sealed together in order to close the inner container and to connect the outer case to the inner container.

This method of connecting has the disadvantage that the inner container must be of a specific form i.e. provided with a flange, and also that the lid portion, inner container and body portion must be arranged in accurate position of relationship for the effective sealing step. Furthermore the materials of the inner container, lid portion and body portion must be compatible if they are capable of being sealed together.

Additionally, the lid portion seals the open top of the inner container, and this may not always be required.

The present invention is a modification of this construction, and provides that the peripheral portion of the lid is sealed directly to the flange of the body portion of the outer case the inner container being inside the outer case.

The sealing may be effected by any suitable means such as by adhesive, by heat sealing, ultrasonic welding, radio frequency welding or any other suitable means, it being understood that in the case where sealing is other than by adhesive, then it is necessary that the contacting surfaces of the lid and body portion flange be of compatible materials. For example, the outer case and lid may be formed of plastic coated board such as polyethylene coated board, the plastic coated surfaces of the lid and board being arranged face to face and sealed together.

The lid portion and body portion maycom- prise cardboard or the like sheet material, coated with materials suitable for heat sealing or welding. Such coating materials comprise for example polyethylene, polypropylene, polyester, PVC or the like.

The sealing together of the lid and portion and body portion may be by any suitable means.

If it is required that the inner container should be for holding liquids, the lid can be arranged to seal against the top edge of the inner container to close same, in which case the material of the lid surface facing the container top edge to which it is to be sealed should be compatible with the container top edge so that it can be sealed thereto or it will be necessary to use a suitable adhesive between these contacting surfaces to provide an effective seal.

In the alternative, the inner container could be sealed closed by means of its own cover previously applied.

An advantage of the invention, is that the inner container need not be of the same shape as the cavity created by the outer case, and also the outer case where the sealing takes place between the lid and body flange, when the body and lid are of cardboard material, may be folded upwardly or downwardly in order to reduce the overall space which is taken up by the composite container. This could not be done in the prior art wherein the inner container flange is trapped between the lid portion and the body portion of the outer case.

The body portion may comprise a rectangular tray portion and the lid may comprise simply a flat sheet blank, but it is not essential that the outer case be constructed specifically in this fashion. For example, the outer case may simply cover only side wall portions of the inner container and in the case where the body portion is in the form of a tray, a central region of the base of the tray may be omitted so that in fact the body portion is simply a supporting wrap extending round the inner container wall. In this case, a non-flimsy material would be required for the inner container.

The composite containers, with appropriate selection of materials, are particularly suitable for being used to hold foodstuffs whilst such foodstuffs are being cooked whether in a microwave oven or in a conventional oven.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 is an exploded perspective view of an inner container and outer case combination according to a first embodiment of the invention; Figure 2 is a sectional elevation of the composite container of Fig. 1 when in assembled condition; Figure 3 is an enlarged sectional elevation illustrating how the lid portion and body portion of the outer case of the container of Fig.

-1 are sealed together; and Figure 4 illustrates how the peripheral edge of the outer case can be folded upwardly or downwardly; and Figure 5 is a sectional elevation of a composite container according to a second embodiment of the invention.

Referring to Figs. 1 to 4 of the drawings, the composite container is shown in Fig. 1 and comprises an inner container 10 of plastics material and comprising a base 12, side walls 14, and end walls 16. There is a peripheral flange 18 at the top edge of the container 10 as shown and the inner container may be formed in any suitable manner.

The outer case comprises a lid portion- 20 which is simply a flat sheet typically of cardboard coated on one side with plastics material such as a polyethylene, indicated by numeral 22, and a base portion 24 which is in the form of a tray to receive the container 10 and is- provided with a top flange 26. The body portion 24 is preferably formed with the same material as is the lid portion 20, and the plastic coating is on the inside of the body portion 24 and also on the upper surface of the flange 26.

The inner container 10 fits into the outer case 24 as will be understood, but the flange 18 is narrower than the flange 24 so that the flange 26 extends beyond the flange 18 when the container 10 is in the body 24. The lid 20 is of the same shape and dimension as the outer perimeter of the flange 26 so that when the three components are assembled, a peripheral portion of the lid 20 faces the peripheral portion of the flange 26 which extends beyond the flange 18, as shown in Fig. 2, and in this region beyond the edge of flange 18, the lid portion 20 and body portion 24 are secured together, also as indicated in Fig. 2.

The means for securing and in fact sealing the lid portion and body portion together may comprise heat sealing, high frequency welding, ultrasonic welding, or adhesive, and in each case a pair of dies 28 and 30 are pushed together as indicated by the arrows in Fig. 2 in order to seal the lid portion and body portion as described. The dies may be heated or may be ultrasonic electrodes in order to achieve the sealing as described above.

Fig. 3 shows in enlarged detail the construction of the lid portion 20 and body portion 24 at the peripheral region where they are sealed together. The cardboard of lid 20 is indicated by numeral 32 and the coating by 34 and similarly in relation to the body portion 24, the cardboard is indicated by reference 36 and the coating by 38. It will be seen that in the region 40 where the lid portion and body portion are sealed together, the coatings 34 and 38 are facing and in fact are fused together by a heat sealing or welding process.

The cardboard 32 and 38 of folds round the region of the edge of the flange 18 which is in fact trapped between the lid portion and body portion.

The coating 34 may also be arranged to be fused to the flange 18 in order to seal the interior of container 10 and this sealing to the flange 18 may be performed at the same time as or before or after the sealing together of the lid portion and body portion in the region 40.

Although the inner container 10 is shown as being provided with an outwardly turned flange 18, it could be provided with an inwardly turned flange 18 or no flange at all in which case the outer body portion flange 26 and the region of the lid sealed thereto could either be turned upwardly as indicated by reference 42 in Fig. 4, or downwardly as indicated by reference 44 in Fig. 4 reiative to the outer case 24 thereby ensuring that the package takes up the minimum of width and length which enhances the storage space utilisation capabilities of the package. The folding upwardly and folding downwardly of flange 26 and the associated portion of the lid 20 is enhanced by providing appropriate crease lines on these portions so that the corner region can be tucked in as fillets 46 indicated in Fig.

4.

In the arrangement shown in Fig. 5, the outer case 50 is sealed by means of its own lid 52, and the inner container 54 has its own cover 56. Also shown in this figure is a layer 58 of what is referred to as susceptor or receptor material being a material which heats up when subjected to microwave radiation, and the heat can be used for applying a high local temperature to adjacent foodstuff, for example to crisp or brown the foodstuff as described in British Patent Specification No.

2046060. Such susceptor or receptor material can be used in any embodiment of Fig. 1 or any embodiment of this invention.

When the composite container is to be used for the cooking of foodstuff by microwave energy, it is preferred that the inner container be constructed of a suitable plastics material such as polyester terephthalate (PET), but other plastics material can be used when the container is for cooking by conventional oven, or indeed if the foodstuff is a nature which does not require to be cooked or if the contents of the container are other than foodstuff, then a much wider range of plastics material can be used for the inner container.

In a modified arrangement, portions of the outer case 24 may be cut away so as to expose at least a portion of the inner container 10. For example the ends of the outer case could be removed or have cut-out portions and a large portion of the base of the outer case portion 24 could be removed.

Claims (10)

1. A composite container comprising an inner container and an outer case, said outer case comprising a body portion and a lid, wherein the peripheral portion of the lid is sealed directly to a flange of the body portion of the outer case, the inner container being inside the outer case.

2. A composite container according to Claim 1, wherein the sealing is effected by any suitable means such as by adhesive, heat sealing, ultrasonic welding, radio frequency welding or any other suitable means, and in the case where the sealing is other than by adhesive, the contacting surfaces of the lid and body portion flange are of compatible materials.

3. A composite container according to Claim 1, wherein the lid and body portion are of cardboard material which is coated with a sealable plastics material such as polyethylene.

4. A composite container according to any preceding claim, wherein there is receptor or susceptor material between the base of the inner container and body portion of the outer case.

5. A composite container according to Claim 4, wherein the receptor or susceptor material is a loose sheet placed between said inner container and body portion.

6. A composite container according to Claim 4, wherein the receptor or susceptor material is laminated to the base of the inner container or body portion.

7. A composite container according to any preceding claim, wherein the said flange of the body portion and peripheral portion of the lid are adapted to be folded downwardly or upwardly so as to reduce the overall length and width of the composite container for transportation and storage purposes.

8. A composite container according to any preceding claim, wherein the inner container within the outer case is sealed by means of its own cover.

9. A composite container according to any of Claims 1 to 7, wherein the inner container is provided with a flange which is trapped between the said peripheral portion of the lid and the flange of the body portion of the outer case.

10. A composite container substantially as hereinbefore described with reference to any of the embodiments illustrated in the accompanying drawings.