GB2076783A

GB2076783A - Packaging Container

Info

Publication number: GB2076783A
Application number: GB8115001A
Authority: GB
Original assignee: AKERLAND and RAUSING AB; Akerlund and Rausing AB
Current assignee: AKERLAND and RAUSING AB; Akerlund and Rausing AB
Priority date: 1980-05-30
Filing date: 1981-05-15
Publication date: 1981-12-09
Also published as: SE433338B; GB2076783B; SE8004041L

Abstract

A packaging container is formed from a blank having joint flaps (13, 14) joining wall panels (11, 12) and connected to edge flaps (15, 16) of those panels by connection portions (23, 24). The joint flaps (13, 14) are no greater in height than the wall panels (11, 12) and the connection portions (23, 24) are substantially narrower than the width of the edge flaps (15, 16). <IMAGE>

Description

SPECIFICATION A Packaging Container and Blank Therefor The present invention relates to packaging containers and has particular, but not exclusive, application to containers of plastics coated sheet material, especially carboard. The sheet material of the container may be coated on one side thereof or on both sides.

The invention is especially concerned with trays coated with plastics of polyester type, for example polyethylene terephthalate (PETP) of polybutene terephthalate (PBTP), to provide a heat resisting coating which withstands temperatures around 2000C for a substantial time without running. Plastics coated trays of said type are especially suited for foodstoofs and particularly readily prepared dishes which, in order to be consumed, merely need to be heated.

In a specific application, the tray is packed with a pastry mixture in powder form to which water is added and the whole tray and contents thereafter placed in an oven to bake the contents directly in the tray. It is essential that the tray should be powder tight before removal of a cover closing the tray. Unfortunately, the polyester type plastics especially suited for use at oven temperatures are difficult to seal. This difficulty arises, inter alia, from the narrow softening temperature range of said plastics material, especially PETP and PBTP.

An object of the present invention is to provide a packaging container construction which will facilitate powder tightness in trays having a polyester type plastics coating. In particular, it is an object to provide a construction which will permit the use with said trays of relatively simple sealing equipment, especially equipment for dotwise sealing to obtain easily openable characteristics. Basically, the need is to be able to use conventional contact heat jaws above a cover to be sealed on the tray and below horizontally outwardly extending edge flanges, which normally exist in tray constructions of this kind and against which sealing of the cover occurs.

In general terms, it has been found that a special design of container corner permits uniformly distributed heat transfer through the edge flange of the container and thereby facilitates the use of polyester type plastics coatings.

According to one aspect of the present invention, there is provided a packaging container formed of sheet material comprising an angulate bottom panel; upstanding wall panels connected along respective edges of said bottom panel; joint flaps inter-connecting adjacent wall panels at the container corners; and edge flanges connected along respective wall panels and extending around the upper edge of the container, wherein the height of the joint flaps is no greater than the height of the respective adjacent wall panels and the joint flaps are connected to respective adjacent edge flanges via connection portions which are substantially narrower than the width of the edge flaps and have their free edges facing outwardly. Usually, but not necessarily, the packaging container will be formed by folding up a single blank of the sheet material.

According to a second aspect of the present invention, there is provided a sheet material blank for erection into a packaging container as defined in the first aspect of the invention, said blank comprising an angulate bottom panel; wall panels foldably connected along respective edges of said bottom panel; joint flaps foldably interconnecting adjacent wall panels at the blank corners; and edge flanges foldably connected along the outer edges of respective wall panels, wherein the height of the joint flaps is no greater than the height of the respective adjacent wall panels and the joint flaps are connected to respective adjacent edge flanges via connection portions which are substantially narrower than the width of the edge flaps.

The provision of corners without free edges facing the internal space of the container, and hence the contents of the container, avoids absorption of water, fat etc. from the contents.

It is preferred that the joint flaps have a maximum height equal to the height of the respective adjacent wall panels.

As mentioned previously, the invention has particular application to packaging containers and blanks having a surface coating of plastics, especially polyester, on at least one side. Usually, but not necessarily, the sheet material will be cardboard coated on at least one side with the plastics material.

Usually, the bottom panel will be rectangular, especially oblong. In a presently preferred embodiment, the packaging tray comprises a bottom panel connected to opposite pairs of side wall panels and end wall panels via crease lines or the like, said side wall panels and end wall panels being inter-connected by joint flaps, and ançedge flange integral with the side wall and end wall panels and extending around the upper edge of the tray, wherein the joint flaps have a maximum height equal to the height of the side walls and end walls, and the joint flaps are connected to respective edge flanges of the side wall panels and end wall panels via connection portions which are considerably narrower than the width of the edge flange and have open cut edges facing outwardly.

In all containers of the invention, it is preferred that the joints flaps form external delta corners and that at least a part of the connecting portion of the inner joint flap at each corner of the container is folded under the edge flange connected to the adjacent wall panel and thereby turns the free edge thereof outwardly. In such a construction, it is possible by pre-creasing blanks to erect the blanks to finished trays by relatively simple erection tools of conventional type whereby the cut surfaces face outwardly as a result of erection of the tray.

The connection portion preferably is folded along a fold line which extends from the crossing point between the line of connection of the edge flange to the adjacent wall panel and the line of connection of the joint flap to said wall panel out of the free edge of the connection portion. It is particularly preferred that the outer joint flap at each corner has a crossing point corresponding to said crossing point of the inner joint flap and said crossing point of the outer joint flap is located at a distance from the free edge of the corresponding connection portion, said two crossing points substantially coinciding and said outer flap connection portion being placed under the inner flap connection portion and also turning the free edge thereof outwardly.

In order to permit sealing of the outer joint flap against the external side of the container in an external delta corner construction, it is preferred that the inner joint flap at each corner has a cut out at the upper edge thereof.

The following is a description by way of example only and with reference to the accompanying drawings of some presently preferred embodiments of the invention. In the drawings: Figure 1 is a plan view showing two tray blanks of the invention, namely a blank shown in solid lines in which the blank is coated on both sides thereof and a modification shown by broken lines in which the blank is coated on one side only; Figure 2 is a partial plan view showing a corner of two further tray blanks of the invention; namely a blank shown in solid lines in which the blank is coated on one side only and a modification shown in broken lines in which the blank is coated on both sides; Figure 3 shows the corner of the solid line blank of Figure 2 in an erected tray and seen from outside the tray, and Figure 4 shows the same corner as Figure 3 but seen from the outside of the tray.

Referring first to Figures 1 and 2, a tray blank of the invention comprises a bottom panel 10, opposite side wall panels 11, opposite end wall panels 12, a pair of joint flaps 13, 14 between adjacent side wall and end wall panels, side wall flanges 1 5 and end wall flanges 16. In the embodiment shown in solid lines in Figure 1, the blank is coated on both sides, preferably by PETP or PBTP. The broken line 17 in Figure 1 indicates a modified version which-is coated only on the side which will be inside the erected tray. This coated side is the side facing upwards in the embodiment shown in solid lines in Figure 2. The broken line 1 7 in Figure 2 relates to a version which is coated on both sides.

In order to erect the blank into a finished tray, it is preferred that hot air guns heat the coating of the blank in the shaded areas shown in Figures 1 and 2 to a temperature at which the plastic coating softens. Thereafter, the blank is pushed through an erection shaft of a conventional type having a cross-section corresponding to the blank and folding elements for the joint flaps and the edge flanges.

It is to be noted that the joint flaps 13, 14 have been given such a height that they are directly placable against the outside of the end wall 12 without any doubling or three-folding of the material thickness of the end wall flange 1 6. The joint flaps have a maximum height equal to the side wall and end wall height. The folding of the joint flaps is carried out along creasing lines 18, 19, 20. The flap 14 is the inner joint flap while the flap 13 is the outer joint flap of the finished external delta corner.

In the erection tool, the side wall flange 1 5 and end wall flange 1 6 are also folded out to a more or less horizontal position along the crease lines 21, 22. In this connection, it should be noted that the crease lines 21,20 and 18, 22 respectively are so formed that between a respective edge flange 15, 16 and joint panel part 13, 14 belonging thereto, there are formed the connection portions 23, 24. The actual corners of the tray, at least seen from the inside and with regard to the cover, are formed where the crossing points between the crease lines 20, 21 and 1 8, 22 coincide in the erected tray. This means that said connection portions, which thus seen from the inside of the tray lie outside the actual corners, effectively turn the free cut edges outwardly at the corner regions. This condition is still more emphasized if the edge flange 16 of the connection portion 14 is given a crease line 25 extending from the crossing point between the crease lines 1 8, 22 to the open cut surface of the flange 1 6 and connecting portion 24.

The minor extension of the doubling of material of the flange 16 which is due to the folding along the crease line 25 may be neglected from a cover tightness point of view with regard to uniformly distributed heat transfer. Any loss in heat transfer uniformity is compensated by the advantages given by the outwardly facing cut surfaces.

Claims

1. A packaging container formed of sheet material comprising an angulate bottom panel; upstanding wall panels connected along respective edges of said bottom panel; joint flaps inter-connecting adjacent wall panels at the container corners; and edge flanges connected along respective wall panels and extending around the upper edge of the container, wherein the height of the joint flaps is no greater than the height of the respective adjacent wall panels and the joint flaps are connected to respective adjacent edge flanges via connection portions which are substantially narrower than the width of the edge flaps and have their free edges facing outwardly.

2. A container as claimed in Claim 1 wherein the joint flaps have a maximum height equal to the height of the respective adjacent wall panels.

3. A container as claimed in Claim 1 or Claim 2 formed by folding up a single blank of the sheet material.

4. A container as claimed in any one of the preceding Claims wherein the sheet material has a surface coating of plastics on at least one side.

5. A container as claimed in Claim 4 wherein the sheet material is cardboard coated on at least one side with plastics.

6. A container as claimed in Claim 4 or Claim 5 wherein the plastics is a polyester.

7. A container as claimed in any one of the preceding Claims wherein the bottom panel is rectangular.

8. A packaging tray of carboard coated by plastics on one side or both sides thereof of corresponding material, comprising a bottom panel connected to opposite pairs of side wall panels and end wall panels via crease lines or the like, said side wall panels and end wall panels being inter-connected by joint flaps, and an edge flange integral with the side wall and end wall panels and extending around the upper edge of the tray, wherein the joint flaps have a maximum height equal to the height of the side walls and end walls, and the joint flaps are connected to respective edge flanges of the side wall panels and end wall panels via connection portions which are considerably narrower than the width of the edge flange and have open cut edges facing outwardly.

9. A container as claimed in any one of the preceding Claims wherein the joint flaps form external delta corners and at least a part of the connection portion of the inner joint flap at each corner of the container is folded under the edge flange connected to the adjacent wall panel and thereby turns the free edge thereof outwardly.

10. A container as claimed in Claim 9, wherein the connection portion is folded along a fold line which extends from the crossing point between the line of connection of the edge flange to the adjacent wall panel and the line of connection of the joint flap to said wall panel out to the free edge of the connection portion.

11. A container as claimed in Claim 10 wherein the outer joint flap at each corner thereof has a crossing point corresponding to said crossing point of the inner joint flap, and said outer flap crossing point is located at a distance from the free edge of the corresponding connection portion, said two crossing points substantially coinciding and said outer flap connection portion being placed under the inner flap connection portion and also turning the free edge thereof outwardly.

12. A container as claimed in any one of Claims 9 to 11 , wherein the inner joint flap at each corner has a cut-out at the upper edge thereof to allow the sealing of the outer joint flap against the external side of the container.

1 3. A container substantially as hereinbefore described with reference to Figure 1 or Figures 2 to 4 of the drawings.

1 4. A sheet material blank for erection into a packaging container as claimed in Claim 3, said blank comprising an angulate bottom panel; wall panels foldably connected along respective edges of said bottom panel; joint flaps foldably interconnecting adjacent wall panels at the blank corners; and edge flanges foldably connected along the outer edges of respective wall panels; wherein the height of the joint flaps is no greater than the height of the respective adjacent wall panels and the joint flaps are connected to respective adjacent edge flanges via connection portions which are substantially narrower than the width of the edge flaps.

15. A blank as claimed in Claim 14 wherein the joint flaps have a maximum height equal to the height of the respective adjacent wall panels.

16. A blank as claimed in Claim 14 or Claim 15 wherein the sheet material has a surface coating of plastics on at least one side.

17. A blank as claimed in Claim 1 6 wherein the sheet material is carboard coated on at least one side with plastics.

18. A blank as claimed in Claim 16 or Claim 17 wherein the plastics is a polyester.

19. A blank as claimed in any one of Claims 14 to 18 wherein the bottom panel is rectangular.

20. A blank of cardboard coated by plastics on one side or both sides thereof or of corresponding material for erection into a packaging container as claimed in Claim 8, comprising a bottom panel connected to opposite pairs of side wall panels and end wall panels via crease lines or the like, said side wall panels and end wall panels being inter-connected by joint flaps, and an edge flange integral with the side wall and end wall panels for extending around the upper edge of the tray, wherein the joint flaps have a maximum height equal to the height of the side walls and end walls, and the joint flaps are connected to respective edge flanges of the side wall panels and end wall panels via connection portions which are considerably narrower than the width of the edge flange.

21. A blank as claimed in any one of Claims 14 to 20 wherein the joint flaps form external delta corners and at least a part of the connection portion of the inner joint flap at each corner of the container is foldable under the edge flange connected to the adjacent wall panel and thereby turns the free edge thereof outwardly.

22. A blank as claimed in Claim 21, wherein the connection portion is foldable along a fold line which extends from the crossing point between the line of connection of the edge flange to the adjacent wall panel and the line of connection of the joint flap to said wall panel out to the free edge of the connection portion.

23. A blank as claimed in Claim 22 wherein the outer joint flap at each corner thereof has a crossing point corresponding to said crossing point of the inner joint flap, and said outer flap crossing point is located at a distance from the free edge of the corresponding connection portion, said two crossing points substantially coinciding and said outer flap connection portion being locatable under the inner flap connection portion and also turning the free edge thereof outwardly.

24. A blank as claimed in any one of Claims 21 to 23, wherein the inner joint flap at each corner has a cut-out at the upper edge thereof to allow the sealing of the outer joint flap against the external side of the container.

25. A blank substantially as hereinbefore described with reference to and as shown in Figure 1 or Figure 2 of the drawings.