The present invention relates to a tray for different goods, such as food, ready meals and other products packed in disposable trays. The inventive tray allows for a reduced weight and a cost-effective production.

BACKGROUND ART

There is an increasingly large demand for food, meals and also other products sold in disposable trays. There are several criteria which the tray must fulfil, depending on the use. One important criterion is the amount of material used in the tray in order to obtain a sufficient stability of the tray. Another important criterion is that the tray should at the same time be easy and cheap to produce.

In order to reduce the environmental impact caused by disposable trays, some markets are imposing a specific environmental tax based on the weight of the tray. Different solutions to minimize the weight and at the same time retaining a sufficient stability are known.

One way is to introduce different stability pattern in the tray, e.g. in the form of grooves, channels, ridges, etc in the walls of the tray. Such stabilizing profiles are easy to introduce in pressed trays, e.g. made from paper, aluminium or vacuum formed plastic. Such patterns do however impose problems for injection-moulded plastic trays, since the flow in the tools is obstructed by the pattern.

Another way is to use a material with a low density, e.g. foam materials, having a low weight and an acceptable stability for some use. The volume of such trays is however relatively large, due to the thickness of the material. The larger volume takes away some of the weight advantage for such trays.

There is thus a need for an improved tray, having a reduced weight with a retained stability. There is thus room for an improved tray.

DISCLOSURE OF INVENTION

An object of the invention is therefore to provide an improved tray, which comprises a side wall module and a separate, fixedly attached bottom. A further object of the invention is to provide a method for producing such a tray.

The solution to the problem according to the invention is described in the characterizing part of claim 1 regarding the tray and in claim 11 regarding the method. The other claims contain advantageous embodiments and further developments of the tray.

In a disposable tray comprising a side wall module and a bottom, where the bottom is a separate bottom attached to the side wall module, the object of the invention is achieved in that the bottom is fixedly attached to the side wall module and that the bottom consists of a foil that is thinner than the walls of the side wall module.

By this first embodiment of the tray according to the invention, a tray is obtained, which allows for a reduced weight and a reduced material usage. Further, the inventive tray provides a reduced production cost.

In an advantageous development of the invention, the bottom of the tray is a foil or film. The foil is thinner than the walls of the side wall module. Preferably, the foil is at least 4 times thinner than the walls of the side wall module, and more preferably up to 10 times thinner than the walls of the side wall module. The bottom foil is preferably made from a plastic material or a material with similar properties and may comprise at least one coating layer, preferably a plastic layer or a printed coating. Other layers may also be comprised, depending on the requirements.

In an advantageous development of the invention, the bottom is fixedly attached to the side wall module at the lower rim to the side wall module. This allows for an easy and cost-effective attachment of the bottom foil. The bottom may also be fixedly attached at the lower wall section of the side wall module. This may be advantageous for trays without a lower rim.

In an advantageous development of the invention, the side wall module is produced by injection moulding. When the side wall module is produced by injection moulding, it is also possible to attach the bottom in the same process. Other production methods of the side wall module are also possible, such as thermoforming.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be described in greater detail in the following, with reference to the embodiments that are shown in the attached drawings, in which

Fig. 1 shows a side view of a tray according to the invention,

Fig. 2 shows a split view of the tray according to the invention,

Fig. 3 shows in split view of a second embodiment of the tray according to the invention.

MODES FOR CARRYING OUT THE INVENTION

The embodiments of the invention with further developments described in the following are to be regarded only as examples and are in no way to limit the scope of the protection provided by the patent claims. The invention is concerned with disposable trays, i.e. trays which are intended to be used once, or at least to be opened only once. Such a tray is not adapted to be closed or sealed once it is opened. Such trays are often used for food of different kinds and for ready meals, but may also be used for other types of goods that are to be packed in a sealed and enclosed way. Fig. 1 shows a first embodiment of a tray 1. The tray 1 comprises in the shown example two longitudinal side walls 3, 4 and two transverse side walls 5, 6 interconnected to each other, thereby forming a side wall module 2 made in one piece. The tray further comprises a fixedly attached bottom 7. The side walls 3, 4 and 5, 6 are substantially perpendicular to each other, but other shapes are also possible. A rectangular outer shape is however cost-efficient both to handle and to stack in larger quantities. Another suitable shape is a circular or an oval shape.

The side walls slope somewhat such that the trays can be stacked in each other. This allows for an efficient transportation of empty trays and facilitates the removal of the tray from the production tool. The lower periphery of the side wall module is provided with a lower rim 10 that is adapted to receive a bottom foil that will constitute the bottom 7 of the tray.

The bottom foil is attached in a fixedly manner to the side wall module 2.

The attachment of the bottom foil is preferably made at the same production site in which the side wall module is produced, such that a complete tray is provided. It is of course also possible to attach the bottom at a later stage, if required.

The bottom may be fixedly attached to the lower rim 10 of the tray in different ways. One way to fixedly attach the bottom foil is to use a heat sealing process using a heated plate that melts the bottom foil to the lower rim. The bottom foil will thus be attached in a fixed way to the side wail module. Other means of heating, such as laser, ultrasonic waves or other types of radiation may also be used. It is also possible to use an adhesive to fixate the bottom foil to the side wall module. The context of the bottom being fixedly attached to the side wall module should be understood as the bottom being attached to the side wall module such that it cannot be removed from the side wall module without damage to the bottom or the side walls. The bottom is not adapted to be removed. The bottom is also not provided with any type of removal aid, such as removal tabs or the like. The material of the bottom and the side wall module preferably bond with each other in a strong manner, such as being melted or glued together.

The bottom is preferably made from a material that is different from the material of the side wall module, even if it is also possible to use a bottom material that is the same as the side wall module. A suitable material is a material that comprises at least one layer of a plastic material or a material with similar properties. It is further preferred that the bottom is thinner than the walls of the side wall module. By using a bottom that is thinner than the walls of the side wall module, it is possible to reduce the weight of the tray without negative impact on the stability of the tray. Since the tray is handled by the side walls, the side walls make up the base of the tray and are therefore the parte of the tray that give the tray its stability. Further, trays are stacked on top of each other, which mean that the side walls must be able to withstand the weight of several trays, also when they are packed with goods.

Suitable materials for the bottom foil may be paper or other fiber materials, woven or nonwoven structures, board or even materials comprising metal. The foil is preferably coated or co-laminated with one or more layers in order to provide e.g. a diffusion-proof foil, to provide an adhesion or to provide other properties. A coating may be a plastic based material, a lacquer, a wax or the like which may be applied by using a printing technology. It is possible to provide a coating only partial on the foil, such as applying a sealing coating or adhesive only at the rim section of the foil. The trays for which the invention is most useful have a height that is less than the shortest measure of the width or length of the tray. Preferably, the length of the tray, i.e. the longer measure of the tray, is in the interval of two to eight times the height of the tray, and the width of the tray, i.e. the shorter measure of the tray, is in the interval of one to five times the height of the tray. In such trays, the stability is mainly carried by the side walls and it is thus possible to reduce the bottom thickness without affecting the stability of the tray. The same goes for the lid, which is often a thin foil attached to the upper rim of the tray. For circular trays, the diameter of the tray is preferably in the interval of two to eight times the diameter of the tray.

One advantage of the inventive tray, in which a separate bottom is attached to a side wall module, is that the weight of the tray may be reduced. In a regular injection moulded tray in which the side walls and the bottom is of the same thickness, the weight of the bottom part may be, depending on the dimensions of the tray, in the same order as the side walls.

In an example of a typical food tray used for ready meals, the tray is 45 mm high, 156 mm wide and 196 mm long. In such a tray, the weight of the bottom is about the same as the weight of the side walls, having the same thickness. A typical thickness of such a tray is in the interval of 600 to 1100 μπι. With the use of a thinner bottom, the weight can be reduced. In one example, with a bottom foil that is 10% of the thickness of the side walls, the weight of the total tray can be reduced by approximately a third. Depending on the dimensions of the tray and the used bottom foil, a weight reduction of up to 35% is thus possible. This will in turn reduce the transportation cost of the trays and may also reduce the environmental tax for disposable products, where such a tax is enforced. A further advantage is of course also that the amount of material required for the tray is reduced. Another advantage of the inventive tray is that the production cost of the tray may be reduced. Trays in the form of a tray intended for e.g. food is often produced by an injection-moulding process. A tray in which the bottom is produced at the same time as the side walls requires a high injection pressure and a relatively expensive tool. By producing a separate side wall module with the same dimensions, the injection pressure can be reduced which in turn allows for a smaller injection machine. The injection tool is also simplified which reduces cost. Some of these costs are levelled out by the fact that a separate bottom must be attached in a separate operation, but the total will still add up to a cost reduction.

Also a tray with a bottom of the same thickness as the side walls can be produced in this way. In this case, the separate bottom is produced as a foil having the same thickness as the side walls and is attached to the side walls in a later operation, e.g. by heat. The result is the same as a trays produced by injection moulding but to a lower cost. Such a tray is sometimes of advantage, e.g. when there is a specific requirement on the bottom, e.g. when heavy or sharp products are stored in the tray.

It is also possible to produce an inventive tray by using other processes than injection moulding. One such process is thermoforming in which the tray is produced from a sheet material. Such a tray will be produced with a fixed bottom, but for e.g. weight reasons or in order to save material, the fixed bottom may be cut out and replaced with a thin bottom foil instead. The cut-out bottom can be recycled. In this way, the material required for a tray is reduced also for thermoformed trays. The same applies for other processes where a tray with a fixed bottom is produced, such as vacuum forming or blow moulding. It is also possible to use another material than plastic for the inventive tray. The side wall module may e.g. be produced from paper or a fibre material.

The upper periphery of the side wall module 2 comprises an upper rim 9 that is adapted to receive a lid 8 of some kind. The lid may be made from different materials but is preferably a transparent film that is attached to the upper rim after goods or food has been put in the tray. The lid may be removable or fixedly attached, depending on the intended use of the tray.

When a tray is to be filled with goods in a filling station at the end user, a single tray is brought to a filling station. This may be either a manually operated filling station or an automated filling station. Depending on the goods to pack, the filling station may comprise one or more substations. The main use for the inventive tray is in the food industry. When a ready meal is packed in the tray, the different food products are placed in the tray one after the other. When only one product, such as one food product or one other type of product is packed, the tray is filled in one operation. When the filling of the tray is completed, a lid is mounted to the tray. The lid is preferably mounted to the tray in a heat sealing operation. Commonly known heat sealing apparatuses or machines comprising a heated plate may be used. It is also possible to use a separate lid that is attached to the tray by snap locking.

The main use for the inventive tray is in the food industry. However, also other products that are relatively light weight and require a sealed package are well suited for the tray. Such products may be different products that should be protected from humidity during transportation and storage, such as medical equipment, electronic components, rubber products and light weight metal products. The tray is well suited for sub suppliers throughout the industry. By using a foil for the bottom and lid that prevents light from passing through, the products may also be protected from sunlight and UV-radiation. The tray may also be filled with a protective gas in order to prolong the influence of oxygen that may diffuse through the tray walls or the bottom or lid.

In a second embodiment, the bottom is attached to the lower rim 10 of the tray in a different way. In this embodiment, the bottom foil is attached to the lower wall section 11 of the side wall module. In this example, the bottom foil is folded around the lower rim and extends up a small portion on the side walls, which is the lower wall section. Such a tray may be advantageous for side wall modules that do not have a lower rim, e.g. for production reasons. The foil is in this embodiment attached to the lower wall section with heat or an adhesive.

In a further embodiment, suitable for injection moulding, the bottom is attached to the lower rim 10 of the tray in the injection moulding process. In this embodiment, the bottom is first inserted into the injection moulding tool and held in place by e.g. vacuum or static electricity. Thereafter, the side wall module is moulded, during which the bottom is adhered to the lower rim in a fixed way. The tray is in this embodiment completed in one operation cycle, which provides an efficient way to produce disposable trays.

The invention is not to be regarded as being limited to the embodiments described above, a number of additional variants and modifications being possible within the scope of the subsequent patent claims.

REFERENCE SIGNS

1 : Tray

2: Side wall module

3: Longitudinal side wall 4: Longitudinal side wall

5: Transverse side wall

6: Transverse side wall

7: Bottom

8: Lid

9: Upper rim

10: Lower rim

11 : Lower wall section