Cardboard tray

Abstract

The present invention relates to a cardboard tray. The cardboard tray of the present invention comprises a bottom wall, a plurality of upright side walls and an equal number of upright corner walls arranged alternately along the periphery of the bottom wall, and a plurality of peripheral flanges arranged to butt against each other, each peripheral flange being arranged along an upper edge of the corresponding upright side wall via a fold line. A reinforcing flange is arranged along the upper edge of each upright corner wall via a fold line, and one reinforcing flange is bonded to both peripheral flanges of adjacent upright side walls. The peripheral flange has a sealing area extending along the peripheral flange and covering at least a portion of the width of the peripheral flange. The reinforcing flange at least partially overlaps the sealing area when viewed perpendicularly to the sealing area.

Description

[Technical field]

[0001] The present invention relates to a cardboard tray comprising a bottom wall portion, a number of upright side walls and an equal number of upright corner walls arranged alternately along the periphery of the bottom wall portion, and a peripheral flange consisting of a number of peripheral flange portions abutted against each other, each peripheral flange portion being arranged along an upper edge of a corresponding one of the upright side walls via a fold line, the peripheral flange having a seal area extending along the peripheral flange and spanning at least a portion of the width of the peripheral flange. [Background technology]

[0002] Such a cardboard tray is known from DE 196 54 230 A1. The cardboard tray of DE 196 54 230 A1 is folded from a cardboard sheet and is kept in a predetermined shape by connecting adjacent wall sections by glued flaps. After such a cardboard tray is prepared, it is filled with e.g. fruits or vegetables and sealed with a plastic film on the peripheral flange. A disadvantage here is that due to the tension in the plastic film, which usually occurs when the plastic film cools down to room temperature, the peripheral flange rolls up (curls) upwards in order to relieve said tension. This impairs the aesthetic appearance and also makes it impossible to stack several similarly sealed cardboard trays.

[0003] WO 2018 / 178508 discloses another corrugated tray. It is explained in WO 2018 / 178508 that gaps may occur between adjacent peripheral flanges. To solve this problem, a butt joint is provided between the butt edges of the peripheral flanges. In order to prevent the butt joint between the peripheral flanges from being damaged during the packaging operation of the corrugated tray, a support flange is arranged on the corner wall. The support flange may be glued to the peripheral flange, but according to WO 2018 / 178508, it is important that the support flange is dimensioned so that it does not overlap the sealing area when viewed perpendicularly to the sealing area.

[0004] In the cardboard tray of Patent Document 2 (WO 2018 / 178508), the plastic film also causes the peripheral flange portion having the sealing area to curl upward.

[0005] EP 3768118 A1 proposes a cardboard tray with multiple double-folded peripheral flanges, each of which is glued to the outside of an upright side wall, to prevent the flanges from curling upwards when a plastic film is sealed onto the peripheral flanges.

[0006] However, due to the complexity of the double folded flanges, special machinery is required to fold such corrugated trays from blanks.

[0007] Furthermore, such rectangular cardboard trays cannot be used with typical top sealing equipment and tools used for plastic trays (which typically have rounded edges). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] DE 19654230 A1 [Patent Document 2] International Publication No. 2018 / 178508 [Patent Document 3] European Patent Application Publication No. 3768118 Summary of the Invention

[0009] The object of the present invention is to mitigate or eliminate the above mentioned drawbacks.

[0010] This object is achieved by a cardboard tray according to the invention, characterized in that a reinforcing flange is arranged along an upper edge of each upright corner wall via a fold line, one reinforcing flange being glued to both peripheral flanges of adjacent upright side walls, the reinforcing flange at least partially overlapping the sealing area when viewed perpendicularly to the sealing area.

[0011] In the cardboard tray according to the present invention, the corners are reinforced (strengthened) by bonding the reinforcing flange to the peripheral flange. Therefore, even if a plastic film is bonded to the sealing area, the peripheral flange is less likely to roll up (curl). The crease line of the reinforcing flange is offset at an angle to the crease line of the peripheral flange, so that the reinforcing flange prevents the peripheral flange from bending along the crease line. Furthermore, because the reinforcing flange is bonded to the peripheral flange, the bilayer portion at the periphery may be more resistant to bending or bending. Furthermore, the presence of the bilayer creates tension between the peripheral flange and the reinforcing flange when the bilayer is pulled upward. This tension resists the bilayer from rolling up (curling up).

[0012] The corners of the tray are reinforced relative to the rest of the perimeter flange, allowing additional tension to be applied to the plastic film sealed to the tray, resulting in a smoother appearance and allowing more trays to be stacked.

[0013] As a result, the present invention provides a corrugated tray suitable for fruits and vegetables (i.e., a corrugated tray that may be provided with multiple vent holes) that can be manufactured in-line or off-line, and the upright corner walls provide a rounded corrugated tray that can be used with the same conventional top sealing equipment and tools used for plastic trays.

[0014] In a preferred embodiment of the cardboard tray according to the present invention, the reinforcing flange portion completely overlaps the sealing area (over the entire sealing area) in the width direction of the peripheral flange.

[0015] By completely overlapping the reinforcing flange portion with respect to the sealing area in the width direction (over the entire sealing area), the area in which the plastic foil (plastic film) can transmit tension to the peripheral flange is reliably reinforced.

[0016] The peripheral flange portion extends along the upright corner wall so that the overlap of the reinforcing flange portion in the circumferential direction is along its entire length.

[0017] In yet another preferred embodiment of the cardboard tray according to the present invention, the angle between the upper edges of adjacent upright side walls and the upper edges of the upright corner walls is greater than 0° and less than 90°, preferably greater than 35° and less than 55°, more preferably 45°.

[0018] Such angles between the upper edges of adjacent upright side walls and the upper edges of the upright corner walls provide additional strength to the corners where the reinforcing flange portions are bonded to the perimeter flange portions.

[0019] In yet another preferred embodiment of the cardboard tray according to the present invention, the joining angle of the butt edges of two adjacent peripheral flange portions is smaller than the angle between the upper edges of the two upright side wall portions corresponding to the two adjacent peripheral flange portions.

[0020] The angle of the butt edges is smaller than the angle between the upper edges of the two upright side walls, so that the peripheral flange slopes downward from the upper edges of the upright side walls toward the outside of the cardboard tray. This downward slope of the peripheral flange further increases the resistance of the peripheral flange to curling up. This can increase the tension of the plastic foil (plastic film) sealed to the top of the cardboard tray.

[0021] In another embodiment of the cardboard tray according to the present invention, at least one of the peripheral flange portions extending along the upright corner wall is provided at at least one longitudinal end with an adhesive flap that is adhesively attached to the upright corner wall.

[0022] The adhesive flap bonded to the upstanding corner wall provides an additional connection between the perimeter flange and the upstanding corner wall which, in combination with the reinforcing flange portion of the upstanding corner wall bonded to the perimeter flange, provides a stronger structure to the corner portion of the corrugated tray.

[0023] In another embodiment of the cardboard tray according to the invention, at least one of the upright side walls is provided with an adhesive flap which is glued to the upright corner wall adjacent to said upright side wall.

[0024] The advantage of each of the above described embodiments is that only the upright corner walls need to be coated with adhesive and the cardboard tray can be folded from an unfolded sheet (blank sheet) by a simple folding device into a structurally strong cardboard tray that will retain its shape once the adhesive has set.

[0025] In yet another embodiment of the cardboard tray according to the invention, at least one of the peripheral flange portions comprises a first elongated flange portion, a second elongated flange portion and a third elongated flange portion which are parallel to each other and connected along an elongated edge, the first elongated flange portion being disposed along the corresponding upright side wall portion, the second elongated flange portion being double folded against the first elongated flange portion, the third elongated flange portion being parallel to the second elongated flange portion and connected along an elongated edge, and the third elongated flange portion being glued to either the inside or outside of the corresponding upright side wall portion.

[0026] In this embodiment, the peripheral flanges running along the upright side walls are also reinforced, so that the corners of the cardboard tray are reinforced as well as the sides. Such reinforced peripheral flanges are described in WO 2019 / 179930.

[0027] Yet another embodiment of the cardboard tray of the present invention further comprises a plastic film covering the cardboard tray, the plastic film being sealed along the peripheral flange in the sealing area.

[0028] In yet another embodiment of the cardboard tray of the present invention, a quantity of adhesive or glue is disposed between each of the reinforcing flange portions and both of the corresponding peripheral flange portions, the quantity of adhesive or glue extending between the butting edges of both of the peripheral flange portions.

[0029] Here, the adhesive or pressure sensitive adhesive is not only used to bond the reinforcing flange to the peripheral flange, but also to fill the gap that occurs between the butting edges of the peripheral flanges, so that when the plastic film is laminated to the inside of the cardboard tray, no groove is formed at the transition from one peripheral flange to the other, and then a perfectly smooth sealing surface is created, which allows the plastic film covering the cardboard tray to be sealed airtight. [Brief description of the drawings]

[0030] These and other features of the present invention will be explained in conjunction with the accompanying drawings.

[0031] [Figure 1] 1 is a perspective view of a cardboard tray according to a first embodiment of the present invention; [Diagram 2] 2 shows a sheet for the cardboard tray according to FIG. 1 in the unfolded state. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 2 shows a bottom view of a corner portion of the cardboard tray of FIG. 1. [Diagram 5] 11 shows a portion of a sheet of a cardboard tray in an unfolded state according to a second embodiment of the present invention. [Figure 6] 6 shows a cross-sectional view of a cardboard tray folded from the unfolded sheet of FIG. 5. [Figure 7] FIG. 11 is a perspective view showing a part of a cardboard tray according to a third embodiment of the present invention. [Figure 8] 8 shows a cross-sectional view of the cardboard tray of FIG. 7. [Figure 9A] 4 is a cross-sectional view showing details of a corner portion of the cardboard tray according to the present invention. FIG. [Figure 9B] 4 is a cross-sectional view showing details of a corner portion of the cardboard tray according to the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] 1 shows a perspective view of a cardboard tray 1 according to a first embodiment of the present invention. The cardboard tray 1 comprises a bottom wall 2 having, for example, eight sides, and a plurality of upright side walls 3 and a plurality of upright corner walls 4 rising from the periphery of the bottom wall 2. The upright side walls 3 and the upright corner walls 4 are alternately arranged in the circumferential direction of the bottom wall 2.

[0033] A number of adjacent peripheral flanges 5 are disposed along fold lines 6 on the upper edge of a respective one of the upright side walls 3. Each peripheral flange 5 extends beyond the fold line 6 at each longitudinal end to the edge of the adjacent upright corner wall 4.

[0034] As shown in Figure 2, a reinforcing flange 7 is disposed at the upper end of each upright corner wall 4 along fold line 8. The reinforcing flange 7 is adhered to the underside of the extension of the peripheral flange 5 to hold the cardboard tray 1 in the folded-in position (assembled state).

[0035] Fig. 3 shows a cross-sectional view of a cardboard tray 1 according to the present invention. As clearly shown in Fig. 3, the reinforcing flange portion 7 is bonded to the lower surface (bottom) of the peripheral flange portion 5. A sealing area (seal zone) 9 is formed (defined) on the peripheral flange portion 5 to which a plastic sheet (plastic film) 10 is sealed. The reinforcing flange portion 7 is provided to span at least a portion of the width of the peripheral flange portion 5. This allows the sealing area 9 to overlap the reinforcing flange portion 7 at least partially, preferably completely as shown (see Fig. 4).

[0036] 5 shows a portion of a sheet (blank sheet) in an unfolded state of a cardboard tray 20 according to a second embodiment of the present invention. The cardboard tray 20 has a bottom wall portion 21, a plurality of upright side walls 22, and a plurality of upright corner walls 23. Each upright side wall portion 22 has a peripheral flange portion 24. The peripheral flange portion 24 is extended in the longitudinal direction so that a longitudinal end portion 25 of the peripheral flange portion 24 is located above a reinforcing flange portion 26 disposed on the upright corner wall portion 23. This is similar to the cardboard tray 1 of the first embodiment shown in FIG. 1.

[0037] The lower edges 27, 28 of the upright side walls 22 are formed partly by score lines 27 and partly by crease lines 28. When the sheet in its unfolded state as shown in Figure 5 is folded into the cardboard tray 20 as shown in Figure 6, the score lines 27 form foot elements which space the bottom wall 21 from the resting surface on which the cardboard tray 20 rests.

[0038] The joining angles α1, α2 of the butt edges of two adjacent peripheral flanges 24 are smaller than the angle β formed between the upper edges of the two upright sidewalls 22 corresponding to the two adjacent peripheral flanges 24. When the cardboard tray 20 is folded into a predetermined shape, the peripheral flanges 24 need to be angled downwards in order to form a smooth peripheral flange by butting their longitudinal edges together (see FIG. 6). The downward sloping peripheral flanges provide additional strength to the cardboard tray 20.

[0039] FIG. 7 shows a cardboard tray 30 according to a third embodiment of the present invention. The cardboard tray 30 comprises a bottom wall 31, an upright side wall 32 and an upright corner wall 33. A first elongated flange 34, a second elongated flange 35 and a third elongated flange 36 are connected to the upper edge of the upright side wall 32. The first elongated flange 34, the second elongated flange 35 and the third elongated flange 36 are connected parallel to each other and along the elongated edge (see FIG. 8). The first elongated flange 34 and the second elongated flange 35 are folded twice and the third elongated flange 36 is glued to the upright side wall 32. This provides a strong flange along the upright side wall 32. Such a double folded flange may also be provided on the other upright side wall 32 of the cardboard tray 30.

[0040] The second elongated flange portion 35 extends in the longitudinal direction along the upper edge of the upright corner wall portion 33. This upright corner wall portion 33 is provided with a reinforcing flange (not shown) as in the first embodiment of the corrugated cardboard tray 1 and the second embodiment of the corrugated cardboard tray 20. To further strengthen the corner portion, an adhesive flap 37 is provided at the end of the second elongated flange portion 35 and is adhered to the upright corner wall portion 33.

[0041] Additionally, the upright side walls 32 are provided with adhesive flaps 38 along their side edges, which are adhered to the upright corner walls 33 .

[0042] As is evident from this and the previous embodiments, only one side of the upright corner wall 33 needs to be coated with adhesive in order for the entire cardboard tray to fold into the desired shape.

[0043] 9A and 9B show details of a corner of a cardboard tray 40 similar to any of the previous embodiments. The corner of the cardboard tray 40 is provided with an upstanding corner wall 41 having a reinforcing flange 42. The reinforcing flange 42 is adhered to the underside of peripheral flange portions 43, 44 via an adhesive layer 45.

[0044] If the peripheral flanges 43, 44 are not completely butted together, the adhesive may overflow from the space between the peripheral flanges 43, 44, forming a bulge 46.

[0045] Once the plastic sheet 47 is laminated to the peripheral flanges 43, 44, the bulges 46 are smoothed out (see FIG. 9B) to create a smooth sealing area and provide an airtight seal for the plastic sheet 47 over the peripheral flanges 43, 44.

[0046] By dimensioning the perimeter flange corner radius, perimeter flange width, and width of the upstanding side walls and upstanding corner walls, a corrugated tray can be provided that matches the dimensions of a conventional plastic tray, allowing users to maintain their existing top seal equipment and tools without additional investment, and to process both types interchangeably.

[0047] The reinforced corners of the cardboard tray of the present invention provide sufficient strength to the elongated sides of the cardboard tray to ensure that the cardboard tray, when filled with, for example, fruits and vegetables, will engage with the tools of existing top sealing devices in the same way as plastic trays, i.e. the elongated sides of the cardboard tray will not flex and the filled cardboard tray will not fall out of the top sealing device.

Claims

1. A bottom wall portion; a plurality of upright side walls and an equal number of upright corner walls arranged alternately around a periphery of the bottom wall; a peripheral flange including a plurality of mating peripheral flange portions, each peripheral flange portion being disposed along a fold line along an upper edge of a corresponding one of the upright side walls; the peripheral flange having a sealing area extending along the peripheral flange and across at least a portion of the width of the peripheral flange; a reinforcing flange portion disposed along an upper edge of each of the upright corner walls and through a fold line; one reinforcing flange portion is bonded to both of the peripheral flange portions of the adjacent upright sidewall portions; The reinforcing flange portion at least partially overlaps the sealing area when viewed in a direction perpendicular to the sealing area. A cardboard tray characterized by:

2. The reinforcing flange portion completely overlaps the sealing area in the width direction of the peripheral flange.

2. The cardboard tray according to claim 1.

3. the angle between the upper edges of adjacent upright side walls and the upper edges of the upright corner walls is greater than 0° and less than 90°, preferably greater than 35° and less than 55°, more preferably 45°; The cardboard tray according to claim 1 or 2.

4. a joint angle between the butt edges of two adjacent peripheral flange portions is smaller than an angle between upper edges of two upright sidewall portions corresponding to the two adjacent peripheral flange portions; The cardboard tray according to any one of claims 1 to 3.

5. At least one of the peripheral flanges extending along the upright corner wall is provided at at least one longitudinal end with an adhesive flap that is adhered to the upright corner wall. The cardboard tray according to any one of claims 1 to 4.

6. At least one of the upright side walls is provided with an adhesive flap that is adhered to the upright corner wall adjacent the upright side wall. The cardboard tray according to any one of claims 1 to 5.

7. the at least one peripheral flange portion comprises a first elongated flange portion, a second elongated flange portion, and a third elongated flange portion parallel to one another and connected along elongated edges; the first elongated flange portion is disposed along the corresponding upright sidewall portion, the second elongated flange portion is double folded relative to the first elongated flange portion, and the third elongated flange portion is connected parallel to the second elongated flange portion along an elongated edge thereof; the third elongated flange portion is bonded to either the inside or outside of the corresponding upstanding sidewall portion; The cardboard tray according to any one of claims 1 to 6.

8. Further comprising a plastic film covering the cardboard tray; the plastic film is sealed along the peripheral flange at the seal area; The cardboard tray according to any one of claims 1 to 7.

9. a quantity of adhesive or pressure sensitive adhesive is disposed between each of the reinforcing flange portions and both of the peripheral flange portions corresponding to the reinforcing flange portion; the quantity of adhesive or glue extends between the butting edges of the peripheral flange portions corresponding to the reinforcing flange portions; The cardboard tray according to any one of claims 1 to 8.

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