AU2021206856B2

AU2021206856B2 - A tray

Info

Publication number: AU2021206856B2
Application number: AU2021206856A
Authority: AU
Inventors: Llewellyn Evans
Original assignee: Ball & Doggett Pty Ltd
Current assignee: Ball & Doggett Pty Ltd
Priority date: 2020-11-16
Filing date: 2021-07-22
Publication date: 2022-07-21
Anticipated expiration: 2041-07-22
Also published as: AU2021206856A1

Abstract

P1716AUAU ABSTRACT A unit stackable with identical units to form a stack. The unit comprises one or more trays 1 each comprising a floor 3 and a wall arrangement 5 about the floor. Each unit comprises locating protrusions 7 and locating recesses 9. The unit is 5 shaped to nest within an underlying identical unit. The locating recesses are downwardly open and shaped to receive and cooperate with the locating protrusions of the underlying identical unit to horizontally locate the unit with respect to underlying identical unit. 2/3 11,11a 5b 5a 3,3a 3b 7,7a 5 7,7a 7,7a 7,7a FIGURE 3 7 7 FIGURE 4 9 FIGURE 5 9

Description

2/3

11,11a 5b 5a 3,3a 3b 7,7a

5

7,7a 7,7a

7,7a

FIGURE 3

7 7

FIGURE 4

9 FIGURE 5 9

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A TRAY FIELD

The invention in its various aspects relates to trays, products comprising trays and methods related to trays.

The invention will be described with respect to meat trays for packaging and presenting meat to consumers by way of example only. Variants of the technology disclosed herein may well be applied in other contexts.

BACKGROUND

Modified Atmosphere Packaging (MAP) is employed to extend the shelf life of meat. By shielding the meat from oxidants, the meat can be made more attractive to purchasers for longer.

An existing approach to MAP entails plastic trays that are formed by vacuum forming or injection moulding. The trays are typically manufactured at one facility, and then nested within each other to form a stack that is transported to a meat packing plant.

Within the meat packing plant, the stack of trays is supplied to a denesting machine to automatically separate and release one tray at a time onto a conveyor belt.

For this purpose, meat trays are conventionally formed with upwardly divergent walls and denesting lugs to control the stacking pitch (that is to vertically locate the trays with respect to each other).

Denesting machines sometimes jam due to trays being misaligned with respect to each other and/or due to vertically adjacent trays binding with respect to each other. A tight fit between adjacent trays can help to maintain better alignment but a tighter fit can be associated with binding.

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Typical plastic trays are not environmentally friendly. Even trays that are in principle recyclable often find their way into landfill or become litter polluting the environment. There is consumer demand for more environmentally friendly trays.

Pulp moulding is an existing process for producing biodegradable items. The International patent application published as WO 2009/136783 discloses a tray comprising a polymer foil layer laminated to a moulded fibre layer. Figures 1 and 2 herein are closely based on Figures 1 and 3 of WO 2009/136783.

Figure 1 is a perspective view of a tray T. Figure 2 is a perspective cut-away view of a stack of two of the trays T1,T2. The tray T is a rectangular tray with an upwardly divergent wall arrangement whereby the tray Ti is nestable within the underlying tray T2. The denesting lugs L, L1, L2 serve to vertically locate the trays T1,T2 with respect to each other. The walls W1,W2 are a close fit so as to horizontally locate the trays with respect to each other.

The present inventors have recognised that intricate features such as the lugs L can make it more difficult to seal the tray to suit MAP. An existing approach to lamination entails deforming a sheet of barrier film using vacuum and/or a male mould so that the film stretches to conform to the top surface of the substrate. Forming intricate features such as the lugs L typically calls for a thicker film to ensure that the film remains integral as it stretches and deforms to a shape of corresponding intricacy.

The present inventors have also recognised that pulp moulding imposes design limitations not present in injection moulding and/or vacuum forming and that these limitations add to the challenges of producing a tray well adapted to automatic denesting.

With the foregoing in mind, the invention aims to provide improvements, or at least alternatives, in and for trays and for those concerned with trays.

Variants of the technology disclosed herein may be usefully applied in contexts unrelated to pulp moulding, MAP and/or automated denesting.

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SUMMARY

One aspect of the invention provides a tray stackable with identical trays to form a stack;

the tray comprising

a floor;

a wall arrangement about the floor;

locating protrusions;

locating recesses;

a first side; and

a second side opposite the first side;

stop portions;

contacting portions; and

a moulded pulp form;

wherein the tray is shaped to nest within an underlying identical tray at 1800 about a vertical axis with respect to the tray;

the locating recesses are downwardly open and shaped to receive and erate with the locating protrusions of the underlying identical tray to horizontally locate the tray with respect to the underlying identical tray;

two of the locating protrusions are on the first side;

two of the locating protrusions are on the second side;

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two locating recesses are bracketed by the locating protrusions on the first side; and

two locating recesses bracket the locating protrusions on the second side;

the contacting portions are arranged to contact the stop portions of an overlying identical tray to vertically locate the overlying tray with respect to the tray;

the stop portions and the contacting portions are configured to define approximately horizontal contact interfaces.

Also disclosed is a unit stackable with identical units to form a stack;

the unit comprising one or more trays each comprising

a floor; and

a wall arrangement about the floor;

each unit comprising

locating protrusions; and

locating recesses;

wherein the unit is shaped to nest within an underlying identical unit; and

the locating recesses are downwardly open and shaped to receive and cooperate with the locating protrusions of the underlying identical unit to horizontally locate the unit with respect to underlying identical unit.

Preferably the unit comprises

stop portions; and

contacting portions arranged to contact the stop portions of an overlying identical unit to vertically locate the overlying tray with respect to the tray.

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The contacting portions may be tops of the locating protrusions. The stop portions may be within the recesses. Preferably the stop portions and the contacting portions are configured to define approximately horizontal contact interfaces.

The locating recesses may have more draft than the locating protrusions.

Preferably each tray comprises a substrate to provide at least most of a strength of the tray; and

a barrier layer over the substrate.

The substrate is preferably fibre-based, e.g. the substrate may be a moulded pulp substate.

Optionally each tray comprises about a top of the wall arrangement, a rim arranged to be spanned by and bonded to a cover layer to define a sealed chamber within the tray.

The unit may consist of one tray.

Preferably the locating recesses open to an outside of the wall arrangement and/or open to interiors of the locating protrusions.

Optionally the one tray comprises

a first side;

a second side opposite the first side;

two of the locating protrusions on the first side; and

two of the locating protrusions on the second side.

The one tray may comprise

two locating recesses bracketed by the locating protrusions on the first side; and

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two locating recesses bracketing the locating protrusions on the second side.

Also disclosed is a stack of the units.

Also disclosed is a method of producing separated trays comprising supplying the stack to a denesting machine.

Also disclosed is a modified atmosphere package comprising the separated tray.

Also disclosed is a tray comprising

a floor;

a wall arrangement about the floor;

locating protrusions; and

locating recesses;

wherein the tray is shaped to nest within an underlying identical tray; and

the locating recesses are downwardly open and shaped to receive and cooperate with the locating protrusions of an underlying identical tray to horizontally locate the tray with respect to underlying identical tray.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a perspective view of a tray.

Figure 2 is a perspective cut-away view of a stack.

Figure 3 is a perspective view of a tray.

Figure 4 is a plan view of the tray of Figure 3.

Figure 5 is an elevation of the tray of Figure 3.

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Figure 6 is a horizontal cross-section view of a portion of a stack of the trays.

Figure 7 is a transverse vertical cross-section view of a portion of the stack of trays.

Figure 8 is a perspective view of a tray.

Figure 9 is an exploded elevation of a portion of a stack of two trays.

DESCRIPTION OF EMBODIMENTS

The tray 1 comprises a floor 3 surrounded by a wall arrangement 5. In this example, the floor 3 is more or less planar comprising a raised inner portion 3a surrounded by a moat portion 3b. The tray further comprises locating protrusions 7 and locating recesses 9.

The wall arrangement 5 comprises four planar wall sections 5a mutually connected by curved wall sections 5b. A rim 11 runs about the top of the wall arrangement 5 and comprises a planar sealing face 11a. The sealing face 11a is a closed loop and defines a contact surface to which a suitable transparent film is adherable to seal product within the tray 1. In this example, the sealing interface is planar, although in principle other shapes are possible.

In this example, the protrusions 7 and recesses 9 are part of integrated locating formations 7,9 having an approximately uniform wall thickness and in which the recesses 9 open into the hollow interiors of the protrusions 7. Figure 9 illustrates a pair of trays in which the locating features 7',9' are separated. The locating protrusions 7 sit proud of the floor 3 within the wall arrangement 5 and below the rim 11. The recesses 9 open downwardly from the underside of the floor 3 and are positioned to receive and cooperate with the protrusions 7 of an underlying tray.

In this example the tray 1 is a rectangular tray comprising two opposed straight sides. As the word 'side' and similar words are used herein, a long rectangle has two long sides and two short sides. In the example of Figure 9, each of the locating features 7', 9' is defined by a respective thin-walled formation having a shape corresponding to three sides and the ceiling of a truncated four sided pyramid. In this example, one

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of the sides is generally parallel to the length of the tray whilst the other two sides are generally transverse thereto. Other forms, e.g. frustoconical forms, are possible.

Whilst rectangular (e.g. square) trays are preferred, other 4-sided shapes and indeed other shapes more generally are possible, e.g. one version of the tray may comprise two straight opposed sides mutually connected by curved ends. In this case, on one of the opposed sides, the protrusions 7 bracket the recesses 9 whilst on the other side the protrusions 7 are bracketed by the recesses 9. In this way the tray is adapted for A-B stacking, that is for mutually identical trays to be stacked one on top of the other but rotated 1800 (about a vertical axis) with respect to each other. The bracketed recesses are positioned to receive the bracketed protrusions, and the bracketing recesses are positioned to receive the bracketing protrusions.

In this way, the tray 1 constitutes a single stackable unit stackable with identical units to form a stack, e.g. a stack suited to an automated denesting machine. Other options are possible, by way of example two similar but not identical trays might be combined to form a stackable unit. By way of example, a variant A of the tray 1 might comprise two opposed sides each of which has locating protrusions bracketed by locating recesses, whilst a variant B of the tray 1 might comprise two opposed sides each of which has locating protrusions bracketing locating recesses. In this way, the B variant might be stacked atop the A variant to form a unit stackable with identical such A-B units.

Whilst stackable units comprising two trays, or indeed more than two trays, are possible, a stackable unit consisting of a single tray is preferred so that the stacks can be made without having to differentiate between two similar trays.

The protrusions 7 and recesses 9 are configured to cooperate so that protrusions nest within the recesses to align vertically adjacent trays with respect to each other vertically and in both horizontal directions.

Preferably a nominal clearance C between the complementary side walls of the features 7,9 (Figure 7) is a minimum selected based on process tolerances. Most preferably, an interior of the recess 9 has more draft angle than the corresponding

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exterior of the protrusions 7 whereby the clearance C downwardly diverges. In this way the features 7,9 guide each other into mutual alignment to horizontally register the trays without the binding that might occur if mutually parallel surfaces were brought into contact. In this case the nominal clearance C is 0.2mm just below the corner radii and this gap widens downwardly from there.

Each protrusion 7 has a contacting portion 7a in the form of a horizontal top. Each recess 9 comprises a stop portion 9a (Figure 7) in the form of a horizontal ceiling. The contacting portions 7a are arranged to contact the stop portions 9a to vertically locate the vertically adjacent trays with respect to each other. The horizontal portions 7a,9a meet at a horizontal interface to define a positive stop without the potential for binding that might occur at the interface between two drafted surfaces. Preferably the horizontal tops are each at least 3mm, e.g. at least 5mm, wide in a direction normal to the adjacent portion of the wall arrangement. This limits the impact of distortion associated with processes such as pulp moulding. In this example the portions 7a,9a meet at horizontal interfaces within the recesses 9, although there are other possibilities. Some degree of inclination would be tolerable, although preferably the interface is at least 300, or more preferably at least 600, from vertical. Likewise, non planar shapes are possible.

Preferably the protrusions 7 have less draft than the wall arrangement 5 although it is also preferred that at least the locating features 7, 9 have at least 100, or more preferably at least 140, of draft e.g.to suit pulp moulding. Preferably the wall arrangement 5 also has at least 100, e.g. at least 140, of draft. Advantageously, the wall arrangements 5 of vertically adjacent trays clear each other. Most preferably, the locating features 7,9 provide substantially all of the contact between the vertically adjacent trays.

Figure 8 illustrates an alternate tray 101 that is a deeper version of the tray 1 and comprises a wall arrangement 105, locating protrusions 107 and locating recesses 109.

The described trays may be formed of any convenient material, e.g. conventional plastics are possible, although the material is preferably biodegradable, or most

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preferably compostable. Preferred variants of the described geometry enable the tray to be formed by pulp moulding and also be stacked and denested efficiently.

A preferred approach to pulp moulding entails a female mould with a mesh inner layer. The female mould is lowered into the pulp and raised to capture pulp. A male mould is then lowered to depress water from the captured pulp. The male mould is heated, preferably to about 200 0C, to dry the moulded pulp. Preferably the pulp comprises bamboo pulp, e.g. at least 50%, or more preferably at least 70%, bamboo pulp by weight.

In one example of moulding process, tray pulp slurry is prepared in holding tanks and pumped into the moulding tanks when required to maintain a slurry mix comprising about 3% pulp and about 97% water by weight. The pulp is 76.5% Bamboo pulp, 13.5% Wood pulp and 10% cassava starch. Within each moulding tank the slurry is held and a female moulding die is lowered into the slurry. The female die is made of two components, the aluminium mould and an inner mesh. The mesh ensures that fibre is caught inside the mould and does not flow through the holes that are inside the aluminium mould. The mould is raised trapping fibre within the mould.

Once the female mould is raised the male mould is lowered down pressing the fibre and forming the tray. The male mould is heated to 2000 C to dry the pulp. The heated water that is pressed out of the tray escapes through the holes that are within the female die. The dried trays are removed and stacked.

This pulp moulding process produces a form that may either serve as a tray or which may be subject to further processing to suit other applications. By way of example the form may constitute a pulp moulded substrate that is processed to render it gas tight, e.g. gas tight to suit MAP. A preferred approach to sealing the substrate comprises deforming a film to conformally contact and adhere to the top surface of the substrate.

A preferred approach to deforming a film is to draw air through the substrate. Following this approach, an irregular distribution of pulp (and associated variations in a wall thickness) can lead to the film puncturing. Accordingly, preferred variants of

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the substrate have a substantially uniform material thickness throughout. It is also preferred that a mean wall thickness of each tray of a set of trays be within a 10% tolerance of a target wall thickness. It is also preferred that the pulp is substantially homogenous so that the substrate has substantially uniform fibre length throughout. Soft corner radii (e.g. at least 1mm, or preferably at least 2mm), at least about the locating features contributes to the uniformity of the pulp.

The lamination process may commence by inserting substrate form(s) into lamination mould(s). Film can then be drawn above the substrate form(s) and heated before being drawn down due to air, inside the tray and across all the features.

In one example, the unlaminated trays are inserted into the female lamination the laminating film is pulled across the top of the laminator mould. The laminator hot plates are lowered to heat the film up 6500 C. Compressed air is used from above the film to start driving the film into the trays. A vacuum is also created below the tray to ensure the film is drawn fully into the tray. The trays are removed from the mould and transported to die cutting. The trays are placed upside down on top of a male die, a hydraulic press with knives is lowered and cuts the excess off the trays. The finished tray is then packed.

Of course, there are other ways in which a barrier layer might be formed, e.g. a spray coating might be applied. Preferably the resultant tray is a high barrier tray.

Once the tray, complete with its substrate and barrier layer, is complete and similar such trays are complete, the trays can be stacked, e.g. manually stacked. The stack may then be packaged, e.g. within a plastic bag, for transport to a meat packing plant.

At the meat packing plant, the stack can be removed from its package and supplied to a denesting machine, e.g. a spiral denester. As the terminology 'denesting machine' and similar terminology are used herein, a denesting machine may be integrated as part of a larger machine, e.g. integrated with a conveyor onto which the denested trays are dropped.

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In this example, the tray 1 is configured to stack at a stacking pitch SP of 6mm (Figure 7) so as to define a gap G of 3mm into which the separating element(s) is insertable to separate the trays. In preferred variants, the denesting machine is a spiral denester comprising one or more helixes arranged to enter the gap G.

Despite the difficulties of pulp moulding, preferred variants of the described geometry provide for a uniform gap G and minimal movement between the vertically adjacent trays to suit efficient denesting.

The invention is not limited to the examples disclosed herein. Rather the invention is defined by the claims.

The term 'comprises' and its grammatical variants has a meaning that is determined by the context in which it appears. Accordingly, the term should not be interpreted exhaustively unless the context dictates so.

Claims

P1716AUAU 13 CLAIMS

1. A tray stackable with identical trays to form a stack;

the tray comprising

a floor;

a wall arrangement about the floor;

locating protrusions;

locating recesses;

a first side;

a second side opposite the first side;

stop portions;

contacting portions; and

a moulded pulp form;

the locating recesses are downwardly open and shaped to receive and cooperate with the locating protrusions of the underlying identical tray to horizontally locate the tray with respect to underlying identical tray;

two of the locating protrusions are on the first side;

two of the locating protrusions are on the second side;

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two of the locating recesses are bracketed by the locating protrusions on the first side; and

two of the locating recesses bracket the locating protrusions on the second side;

the contacting portions are arranged to contact the stop portions of an overlying identical tray to vertically locate the overlying identical tray with respect to the tray;

2. The tray of claim 1 wherein the contacting portions are tops of the locating protrusions;

the stop portions are within the recesses.

3. The tray of claim 1 or 3 wherein the locating recesses have more draft than the locating protrusions.

4. The tray of claim 1, 2 or 3 wherein each tray comprises about a top of the wall arrangement, a rim arranged to be spanned by and bonded to a cover layer to define a sealed chamber within the tray.

5. The tray of any one of claims 1 to 4 wherein the locating recesses open to an outside of the wall arrangement.

6. The tray of any one of claims 1 to 5 wherein the locating recesses open to interiors of the locating protrusions.

7. The tray of any one of claims 1 to 6 wherein the moulded pulp form is a substrate to provide at least most of a strength of the tray; and

a barrier layer over the substrate.

8. A stack of trays each in accordance with any one of claims 1 to 7.

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9. A method of producing separated trays comprising supplying the stack of trays of claim 8 to a denesting machine.

10. A modified atmosphere package comprising a separated tray produced in accordance with claim 9.