Both aluminium and semi-corrugated board are currently used for trays in the food industry (particularly the baking industry) and have advantages over existing carton trays in respect of structural strength, rigidity and oven durability. However they suffer from the disadvantage of poor printability. If a printed surface is required, external printed flow-pack film is used, which is expensive.

Aluminium trays have the further disadvantage that they cannot be reheated in a microwave oven and also present an environmental and potential health hazard.

An object of the present invention is to overcome or alleviate at least some of the above disadvantages.

In one aspect the invention provides a self-supporting receptacle for a food product, the receptacle being formed from a flat sheet folded into sidewalls which extend upwardly from a base portion, adjacent ends of adjoining sidewalls being joined by a connecting portion which comprises two panels folded together about an upwardly- extending fold line to form a flap which lies against one of the adjoining sidewalls, the flap tapering from its upper end towards its lower end.

The resulting receptacle is easy to open, and also has a relatively rigid construction which is strengthened by the flap. Furthermore, since each connecting portion is formed from material which is normally removed when making a blank, wastage of material is reduced.

Furthermore the receptacle can easily be made leakproof.

To this end, preferably the region of the sheet constituting said connecting portion is uncut at any level between the base and the top of the flap.

Preferably the flap extends to substantially the full height of said adjoining sidewalls. This preferred feature ensures that any material which leaks into the flap between the panels cannot escape from the receptacle.

In another aspect the invention provides a self-supporting receptacle for a food product, the receptacle being formed from a flat sheet folded into sidewalls which extend upwardly from a base portion, wherein at least one sidewall is provided with a strengthening flap on its upper edge, the strengthening flap being turned downwardly over the exterior surface of that sidewall and extending outwardly from that sidewall to form a handle.

Preferably the strengthening flap is turned downwardly and inwardly towards its associated sidewall. This increases the rigidity of the handle.

In one embodiment the strengthening flap is folded downwardly and inwardly about a fold which defines the outer edge of the handle.

In another embodiment the strengthening flap is curved to form a tubular or part- tubular portion of the handle.

In another embodiment the terminal portion of the strengthening flap is attached to the outer surface of its associated sidewall.

Preferably the sheet material is heat-resistant leakproof and greaseproof board.

The invention also provides a food package comprising a receptacle as defined above (in accordance with either aspect) which contains a baked or bakable food product.

The invention also provides a blank for a receptacle as defined above (in accordance with either aspect).

Preferred embodiments of the invention are described below by way of example only with reference to Figures 1 to 8 of the accompanying drawings, wherein: Figure 1 is a top plan view of a blank used to make a baking tray in accordance with

theinvention; Figure 2 is a top plan view of one end of the tray in an intermediate configuration as it is being formed from the blank (or unfolded by a consumer to remove the baked food product from the tray); Figure 3 is an end view of the baking tray; Figure 4 is a sketch perspective view of the tray; Figure 5 is a top plan view of another blank used to make another embodiment; Figure 6 is an end view of the resulting tray; Figure 7 is an end view of a similar tray in which the flaps forming the handles are curved down rather than being sharply folded as in Figure 6, and Figure 8 is a schematic side elevation of a baking installation utilising any of the above baking trays.

Throughout the drawings, similar parts are indicated by corresponding reference numerals.

Referring to Figure 1, the blank shown is made of lightweight white printable ovenable board and is optionally coated with PET (polyethylene terephthalate). The reverse (outside) surface of the blank is suitably printed, using a suitable heat- resistant ink approved for food packaging.

Fold lines are indicated by dashed lines in Figure 1 and can be formed by scoring or otherwise weakening (but preferably not by perforating) the blank. These define a base 10, sidewalls 20 and endwalls 30 as shown in Figure 2. A connecting portion joining the adjoining walls comprises two triangular panels 6 and 7 which are separated by a fold line f which extends diagonally from the corner of the base 10.

Two strengthening flaps or handles 5 are formed on the outer edges of the sidewalls 20 and in this embodiment are divided into three panels 1,2 and 3 which are separated by fold lines. A retaining flap 4 is formed along the top edge of each end wall 30.

The rear surface of the blank has glued areas 8 on the sidewall portions which are aligned with and secure the panels 1 when the blank is folded to form the receptacle (as can be seen eg in Figure 3) and has further glued areas 9 extending across the flaps 4 and endwall portions. PVA-based glue is employed for the glued areas.

As shown in Figure 2, the tray is formed by folding panels 6 and 7 towards each other about fold line f and folding the resulting flap against the outer surface of the end wall 30. The retaining flap 4 is then folded downwardly over the flap formed from panels 6 and 7 (which are now face-to-face). The inner portions of glued areas 9 secure the panels 7 to the endwalls 30 and the outer portions of the glued areas 9 (on the rear of flaps 4) secure the flaps 4 over panels 6.

The assembly is completed by folding panel 3 downwardly and outwardly until it is horizontal or inclined slightly downwardly, folding panel 2 inwardly towards the sidewall 20 and folding panel 1 away from sidewall 20 until it is parallel therewith and in contact with glued region 8.

The resulting tray is shown in end view in Figure 3 and in perspective view in Figure 4. The width (ie measured in the direction parallel to the adjacent sidewall in Figure 3) of panel 1 is suitably 8 to 10 mm and the depth of the tray is suitably 30 mm to 75 mm. The handles 5 formed by the strengthening flaps provide rigidity to the tray and the tray can be opened easily by lifting each flap 4 and then unfolding the flaps formed by the panel portions 6 and 7 as shown in Figure 2.

It should be noted that the entire periphery of the blank (and in particular the top edge of the connecting portion formed by triangular panels 5 and 6) lies at or near the top edges of the sidewalls 20 and 30, thereby ensuring that even if any of the contents found their way between panels 5 and 6, such contents could not flow over any edge from the receptacle.

It is not essential for the top edges of the panels 5 and 6 to be exactly aligned with the top edges of the sidewalls 20 and 30 in the finished container (in the described embodiment the top edges the these panels lie about 1 mm below the fold of flap 4 in the assembled receptacle) but it should be noted that the connecting portions (panels 6 and 7) at the edges of the receptacle open out when the receptacle is unfolded to form a sheet similar to the blank of Figure 1 whose edge completely

surrounds the contents of the receptacle and thereby enables the contents (eg a cake) to be sliced on the sheet without the risk of eg cake crumbs falling between the ends of the sidewalls onto the table. This is a further advantage over known aluminium or semi-corrugated trays.

Figure 5 shows a further blank which differs from the blank of Figure 1 by having glued areas 8'nearer the top edge of the sidewalls (allowing a greater area for printing on the outside of the sidewalls) and by having small square glued regions 18'which align with and glue only the flap 4 in the finished tray, the folded-together panels 6 and 7 being held in position mechanically by the flap 4. This feature enables the tray to be opened more easily and can be employed in eg the embodiment of Figure 1 as well.

As shown in Figure 6, during assembly the panel portion 2'is folded upwardly under panel portion 3'into contact therewith to form flat handles 5'on either long side of the tray, the glued areas 8'holding the handles in the configuration shown.

Figure 7 shows a variant of the embodiment of Figure 6 in which the strengthening flaps of the blank have no fold lines and are merely turned down in a smooth curve to form tubular handles 5". The terminal edges of the flaps forming handles 5"are suitably glued to the sidewalls by glue beads 8"in order to increase the rigidity of the construction.

The trays of all three embodiments have outwardly inclined walls which allows them to be stacked. In Figure 8 a stack S of such trays T is shown. The trays T are successively released from the bottom of the stack S onto the moving surface of a conveyor belt C which carries them beneath a filling station F where they are filled with baking mixture before being carried through a baking oven B to provide a baked packed food product eg a cake. Tests have shown that when made with commercially available ovenable board, the trays can withstand temperatures of up to 204 °C for 30 minutes in a conventional oven.

The trays of all the described embodiments are rigid or semi-rigid and are self- supporting.