GB2232566A - Microwavable packaging carton - Google Patents

Abstract

A packaging container containing or for containing contents to be heated by microwave energy, which container is formed from cut and creased sheet material and which is held in erected condition by means of adhesive connecting portions 50, 52, 54, fig 4 of the sheet material, the container including a microwave receptor material sheet 56 thereon, and the container being constructed so that the adhesive is located remote from the receptor so as to be least affected by the heat effects of the receptor material when the container and its contents are subjected to micro-wave heating. <IMAGE>

Description

Improvements relating to Packaging Containers This invention relates to packaging containers, and in particular it concerns a container of the type which is sealed and has a base panel, a top panel and side panels connecting the top and base panels. The container is erected from a one piece blank which is appropriately cut and creased, a common edge panel connecting the base panel and top panel, the remaining sides of the base panel having base edge panels connected thereto, whilst the top panel has top edge panels connected thereto. In the erection of the container, the said common connection panel and base edge panels are moved to the erected condition and then the top panel is folded over to lie opposite the base panel, and finally the top edge panels are folded to overlap the base edge panels and are glued thereto by hot-melt adhesive.The hot-melt adhesive lies between the base edge panels and overlapping top edge panels nearer to and adjacent the base panel.

The present invention relates to containers of the above described nature.

Conventional packaging containers of the above described nature are used for holding microwavable foodstuff, and it is common to place inside the container a sheet of microwave receptor material which lies on the inner surface of the base panel of the container so that the foodstuff rest on the receptor material. The receptor material is a material which when subjected to microwave energy heats-up to a temperature suitable for crisping the surface of the food stuff in contact therewith. Typically therefore, the container of the nature described may be used for holding microwavable chipped potatoes. The chipped potatoes rest on the receptor material and when the package in sealed condition is placed in a microwave oven, the chips are not only heated by the microwave energy, but also are crisped where they contact with the receptor material.The chips therefore have a texture which is similar to chipped potatoes cooked by conventional frying methods.

It is also known to provide the packaging containers of the nature described with lines of weakening so that a panel or a section of a panel or panels can be torn back to expose the container contents for consumption.

A difficulty which arises in connection with the known container when used for microwave heating of the contents and wherein the receptor sheet is also provided is that the heat generated by the receptor sheet has an effect on the hot-melt adhesive due to the close proximity of the adhesive and the receptor sheet. Accordingly, the integrity of the sealed container can be disturbed or destroyed during the microwave cooking, and this is undesirable at least from a marketing point of view.

The present invention seeks to overcome this difficulty by providing a new packaging container which performs the same functions as the existing packaging container, but does not have the disadvantages.

In the earlier arrangement, the erection of the container involves the erection in the first stage of the base edge panels relative to the base, and the top panel is provided with the lines of weakening defining the tear-back section.

The hot-melt adhesive is applied to the surfaces of the top edge panels at the free edges thereof. In the present invention, the arrangement is somewhat inverted in so far as the tear-back section is provided in the top panel, but the top panel is adapted to be erected in the first stage of operation and the adhesive is provided on the free edges of the base edge panels, and therefore in the erected container, the adhesive will be located closer to and adjacent the top panel, and the receptor sheet when provided will be located adjacent the inside of the base panel.

It can be seen therefore that the receptor sheet and adhesive have been arranged in spaced relationship, one being adjacent the base panel the other being adjacent the top panel.

To enhance operation, the receptor sheet may be adhered to the inside surface of the base panel when, as is preferred, the containers are constructed from one piece blanks. The receptor sheets may be adhered to the base panels by a window patching operation.

The tear-back portion may comprise a section of the top panel and a section of one of the top edge panels, the section of the top edge panel being defined by slits or cuts. A bottom edge panel which overlaps said top edge panel containing the slits may provide a means of protecting the said slits from accidental impact during erection and handling of the sealed container, but said base edge panel being cut-away to allow said portion of the top edge panel and an adjacent portion of the top panel to be gripped for the tearing-away of the tearback portion to expose the container contents.

The top edge panels may be adapted to be interlocked by means of interlocking flaps or tabs so as form with the top panel a holding tray and into which the container contents may be placed before the tray is closed by means of the base panel and the base edge panels.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein Fig.l is a plan view of a blank a of known packaging container of the nature to which the invention relates; Fig. 2 is a blank of Fig. 1 when in a partly erected condition; Fig. 3 is a front view of the packaging container shown in Fig. 2 when in the fully erected condition; Fig. 4 is a plan view of blank erectable into a container according to an embodiment of the invention; Fig. 5 is a perspective view of the blank shown in Fig. 4 when in the partially erected condition; Fig. 6 is a perspective view of a packaging container erected from the blanks shown in figs. 4 and 5.

Referring to the drawings, the packaging container blank shown in fig. 1 comprises a base panel 10, a top panel 12 a connecting panel 14 hinged to the base panel 10 and top panel 12 by fold lines 16 18. The base panel 10 has base edge panels 20, 22, 24 connected thereto by a hinge line 26, 28, 30, and top panel 12 has top edge panels 32, 34, and 36 connected therto by hinge lines 38, 40 and 42.

At the ends, panels 14 and 20 have locking tabs 14A, 14B and 20A, 20B which are adapted to enter slits 22A and 24A in base edge panels 22 and 24, as will be described.

As can be seen, panel 10 is of rectangular form and is of the same size as panel 12 whilst panels 20 and 14 also of rectangular form are of identical size. Pannels 22, 24, 34 and 36 are of the same width so that in fact the blank is erectable into a rectangular box configuration as indicated in Fig. 2.

The top panel 12 is provided with skip-cuts 44 which also extend into panel 32 in order to define a tear back section 12A and 32A for gaining access to the container contents as will be described. The lines 44 of skip-cuts meet the free edge of panel 32 symetrically at points 46, 48. The distance between points 46 and 48 should desirably be at least one third of the length of the free edge of panel 32 in order that the section 12A, 32A can be torn back from a wide base.

Finally, the panels 32, 34, 36 are provided with lines of hot-melt adhesive 50, 52 and 54, and it should be noted that the line 52 is in fact made of two lengths lying at opposite sides of the section 32A but not traversing that section as clearly that section has to be torn away in the opening of the package.

In the erection of the blank shown in fig. 1 to the position shown in fig. 2, the base section of the package is initially erectd by means of a conventional punch and die operation so that, as shown in fig. 2, the panels 14, 20, 22 and 24 are moved to a vertical position in relation to the base panel 10, the tabs 14A, 14B and 20A and 20B being interlocked with the said slots 22A and 24A as shown in fig.2 . This method of erection is conventional.

In the next stage of operation, the sheet 56 of receptor material, of approximately the same dimensions as the base panel 10 is simply inserted in the package as indicated by arrow 58 and then the contents are placed on top of the receptor sheet 56. Sealing of the package is completed simply by folding over the panel 12 as indicated by arrow 60 and then the top edge panels 32, 34 and 36 are folded onto the outsides of the erected base edge panels and are glued thereto by means of the glue strips 52, 54 and 50. When it is desired to open the package, the sections 32A and 12A are simply torn-along lines 44.

Fig. 3 shows the disadvantage of this construction. The receptor sheet 56 is adjacent the base panel 10, and the plane containing the adhesive strips 50, 52 and 54 as indicated by reference 62 in fig. 3 is close to or could be coincident with the plane containing receptor sheet 56. With this arrangement, when the package is subjected to microwave heating, the somewhat intense heat created by the receptor sheet 56 is experienced by the adjacent hot-melt adhesive strips 52 and 54 and the hot-melt adhesive becomes deactivated and adhesion can be lost, impairing the integrity of the package, which is undesirable.

By a redesign of the packaging arrangement in accordance with the invention, this disadvantage can be overcome quite simply, and fig. 4 shows a specific embodiment of the blank erectable into the packaging container of the present invention. The same reference numerals have been used to indicate the same or similar function parts, and in the arrangement in fig. 4 it will be noticed that base panel 10 has the edge panels 32, 34 and 36 carrying the adhesive 50, 52 and 54 and therefore these edge panels overlap the edge panels connected to the top 12 which is provided with the edge panels 20, 22 and 24. It is to be noticed however that the edge panel 12 has a tear-back section 20A which does not extend to the free edge of panel 20, and also that the base edge panel 32 has a cut-away portion 70 whose function will be explained hereinafter.

In the erection of the blank shown in fig. 4, the panels around the top panel 12 are erected by a punch and die operation at the position as shown clearly in fig. 5, and it is the base panel 10 which is folded over the tray formed by panel 12 and edge panels 14, 20, 22 and 24, following which the panels 32, 34 and 36 are folded inwardly so as to be sealed by the hot-melt adhesive to the panels 20, 22 and 24.

In this arrangement, the contents of the container are placed into the tray first and then the receptor sheet is placed on top of the contents or in the alternative, as shown in fig.

5, the receptor sheet 56 is in fact window patched to the base panel 10, and this window patching operation can be done during the manufacture of the container blanks as shown in fig. 4, thereby simplifying the filling operation for the person who has to fill the containers. In fact the window patching of the receptor sheets to the blanks provides an important advantage in that it eliminates the possibility of two receptor sheets being placed into any one container. By putting two or more receptor sheets into one container there is created the possibility of a danger of fire when the package is subjected to microwave heating.

When the container has been sealed as described, it is inverted to place it into the correct upright disposition as shown in fig. 6, and the advantage of the invention will be seen from fig. 6 in so far as the receptor sheet 56 is located adjacent the base panel 10, whilst the adhesive line is located adjacent the top panel 12.

To open the container, the section 20A is pressed inwardly in order to fracture the line of weakening 20B effected by the skip-cuts and then the section 20A can be folded to the underside of section 12A and the overlapped sections grasped by the fingers to tear section 12A away from the remainder of the panel 12.

The cut-out 70 is dimensioned so that the edge of the panel 32 adjacent the cut-out 70 in fact overlaps the line of weakening 20B to protect that line during the erection, handling and transportation of the container.

The packaging container will preferably be constructed of cut and creased cardboard materaial, although any other suitable sheet material can be used for this purpose.

Claims (8)

1. A packaging container containing or for containing contents to be heated by microwave energy, which container is formed from cut and creased sheet material and which is held in erected condition by means of adhesive connecting portions of the sheet material, the container including a microwave receptor material thereon, and the container being constructed so that the adhesive is located remote from the receptor so as to be least affected by the heat effects of the receptor material when the container and its contents are subjected to micro-wave heating.

2. A packaging container according to claim 1 wherein the container is provided with lines of weakening so that a section of the container can be torn back to expose the container contents for consumption.

3. A packaging container according to claim 2 wherein the torn back section may comprise a section of the top panel and a section of one of the top edge panels, the section of the top edge panel being defined by slits or cuts.

4. A packaging container according to claim 3 wherein a bottom edge panel overlaps said top edge panel containing the slits or cuts and thus provides a means of protecting the said slits or cuts from accidental impact during erection and handling of the sealed container.

5. A packaging container according to claim 4 wherein said bottom edge panel is cut away to allow said portion of the top edge panel and an adjacent portion of the top panel to be gripped for the tearing away of the tear-back portion to expose the container contents.

6. A packaging container according to any preceding claim, wherein the top edge panels are adapted to be interlocked by means of interlocking flaps or tabs so as to form with the top panel a holding tray into which the container contents may be placed before the tray is closed by means of the base panel and the base edge panels.

7. A packaging container according to any preceding claim wherein the receptor material is adhered to the inside surface of the base panel when the container is constructed from a one piece blank.

8. A packaging container aeeording to claim 7, wherein the receptor material is adhered to the said base panel by a window patching operation.