The present invention relates to a new type of EPS containers, according to the preamble of patent claim 1.

Background

Food, especially fresh fish, is often transported in EPS containers (Expanded Polystyrene).

Transport in EPS containers is the least expensive and efficient way to transport fish. Such a container is light, functional, hygienic, robust and may be adjusted to a European pallet. The fish is placed into the container together with ice, possibly an absorbent, and finally a lid of EPS is laid onto the container, and fastened with straps. Such containers having a lid and straps are well known in prior art, for instance from Bewi AS.

During transportation, most of the ice will melt, and in order to prevent the food from lying in water, which would reduce the quality, most EPS containers are performed with holes for drainage, whereby superfluous water may drain out. During long transportations, water will thus flow out of the containers, and from the vehicle, such as a trailer. This water is mixed with fluids from the fish, and is thus unfavourable discharge. The alternative is to use sufficient amounts of absorbents, which i.a. is done for transportation by plane.

To fill the containers with ice instead of food is very unfavourable, and renders the

transportation expensive. One may also use dry ice instead of wet ice, but dry ice is more expensive, and should not directly touch the food. The alternative for using EPS containers with ice, is to use other containers and perform other ways of cooling during the entire transport. The containers must also be strong enough to be stackable and to allow being moved and handled without danger for falling apart.

Many different types of trays or small containers of XPS - extruded polystyrene are known, for instance from JP 7060922. XPS are produced in flat plates, and an XPS-tray is produced by punching a tray from such an XPS plate. To perform the punching process, the plate must be relatively thin, and thus it is not possible to produce a container of XPS having sufficient strength. The thin walls are not providing sufficient insulation, and the XPS-trays must thus be cooled from the outside.

Object

A main object is that the EPS containers according to the present patent application should be lighter and have smaller outer volume than known EPS containers having the same inner volume. A further object is that the containers should be air- and fluid tight, in order to render the atmosphere inside controllable. Yet another object is that the containers should provide better possibilities for branding.

Trie invention

The objects are achieved with an EPS container according to the characterizing parts of patent claims 1 and 7. Further advantageous features are stated in the accompanied dependent claims.

The invention is related to a container having sidewalls and floor of EPS, wherein the traditional EPS lid is replaced by a plastic film being fastened directly to the EPS container. By using this film a substantial reduction of volume and weight is achieved, and if desirable, it is possible to obtain a container being liquid and/or gas tight. Using a transparent plastic film further makes it easier for the end user to inspect the contents of the container, as it no longer needs to be opened to allow inspection of its contents. The film also offers a good possibility for branding, because it can be printed directly onto the plastic film. Directly printing onto EPS is possible, but the result is often poor, and it causes a lot of wreckage. The alternative is to use stickers, but that involves extra costs and work.

An adhesive is used to fasten the plastic film to the EPS container. Even if this adhesive is not supposed to contact the contents of the container directly, it is still an advantage to use an adhesive being approved by FDA for indirect contact with food. The adhesive must fasten well to EPS, and preferably have a lower melting point than EPS, so that the EPS is not deformed or melted when the adhesive is supplied. When EPS melts, styrene gas is produced, and styrene gas is possibly cancerous for humans.

By "gluing" it is in this application meant use of an adhesive/glue for fastening two parts to each other, releasably or durably. By "adhesive" it is meant any kind of fastening means being suitable for fastening two parts to each other, releasably or durably. Different types of adhesives may be used, preferably adhesives applied in one step, and reactivated in another, for instance adhesives being activated by temperature, pressure, ultrasound or ultraviolet light. It may also be used adhesives applied in one step and cured in another. In an alternative embodiment, a kind of plastic firstly being applied to the EPS container is used, and when the plastic film is applied, the film is welded to the plastic already being applied to the EPS container. It is, of course, a premise that the plastic being applied to the EPS container adheres to EPS, and does not loosen during the welding. A preferred example of an adhesive being reactivated with heat, is ethylene vinyl acetate (CAS# 24937-78-8, also known as EVA). It is a copolymer of ethylene and vinyl acetate. The weight ratio of vinyl acetate is normally varying between 10 and 40%. In an especially preferred embodiment, the adhesive is applied immediately after production of the container, in such a way that the adhesive is applied in a dry, controllable environment. The adhesive may also be applied after the contents of the container is put in place, but then water, ice or other elements might prevent optimal adhesion between adhesive and EPS. After the contents are placed in the container, the adhesive must be reactivated and the plastic film applied. If the characteristics of the adhesive so allows, it may also be moulded into the EPS container during production.

In an alternative embodiment, the upper edge of the sidewalls of the EPS container/is provided with a horizontal, peripheral track where the adhesive is placed, in such a way that the contact surface between EPS and adhesive is as large as possible without changing the thickness of the wall.

The plastic film being placed as lid on an EPS container, must also be approved for food, corresponding to the adhesive. The plastic film is preferably gas tight, and should have high tensile strength, for instance about 13 MPa. Furthermore it is a premise that the film fastens well to the adhesive, and that its properties does not change during the reactivation or curing of the adhesive; for instance it must have a melting temperature higher than the reactivation temperature of the adhesive, in cases where the glue should be reactivated by heat. In order to achieve a film having satisfying characteristics it may be an advantage to use a plastic film comprising several layers, a laminate. Besides, it is preferred to allow printing directly onto the plastic film, possibly on one of the layers if a laminate is being used, and that it is produced in a non-dewing quality.

The invention also comprises a method for producing a container as described above, comprising the steps of

„- moulding a container (1) having sidewalls and floor of EPS in a regular way,

- applying an adhesive on an upper edge of the sidewalls,

- laying a plastic film (5) over the container, and guiding it down at the least until contact with the adhesive is achieved.

The container is filled with desired contents after moulding or preferably after the adhesive is applied.

The method also comprises a further step for reactivating the glue after it is applied onto the container, and most preferably it is reactivated after the plastic film is put onto the box, in such a way that the adhesive will be reactivated through the plastic film. Finally it is an advantage that the plastic film is guided down until contact with the adhesive, and further until contact with the upper edge of the container is achieved. By using EPS containers according to the present invention, one achieves reduced weight and reduced volume. Compared to use of traditional containers this offers large economic cuts upon transportation. When one also may achieve a completely gastight container, the fish may be packed in a controlled atmosphere, and this offers new methods for packaging and transporting fresh fish. For instance a reduction of the amount of ice will contribute substantially to further lower the costs for transportation.

,By replacing the lids with a plastic film, the underside of the floor and the upper part of the sidewalls and/or upper edge may be performed with reciprocal designs, in such a way that the floor of an adjacent container being stacked on top, will function as an insulating lid. This gives a further reduction of the outer volume of the container, and allows more containers to be stacked in; the height, without increasing the outer measures of the pallet. This reduces the transportation costs further.

Example

The invention will in the following be described in the form of an example, wherein a container having sidewalls and floor of EPS is provided with a plastic film lid, and wherein a number of containers are placed on a pallet. The example is shown in the enclosed drawings, where

Figure 1 shows a container having sidewalls and floor of EPS, while adhesive is applied at the upper edge of the sidewalls,

Figure la shows an enlarged section of Figure 1, where the track having applied adhesive is shown in detail,

Figure 2 shows the container of Figure 1, having a plastic film glued in place, and

Figure 3 shows a pallet of containers according to present invention, compared to a pallet of traditional containers.

Figure 1 shows a fish container 1 having sidewalls and floor of EPS (in this case an EPS having a melting temperature of 103°C is used) designed to achieve a plastic film as lid instead of a traditional EPS lid. The container is designed with a horizontal track on the upper edge of the sides of the container, wherein the track is designed to provide a carrier surface for the adhesive. In the shown embodiment in Figure 1, and as shown in detail in Figure la, the adhesive 2 is applied to the track. The upper edges of the container is further provided with a discontinuous, elevated outer edge 3, which is opposite to recesses/grooves 4 in the underside of the container, in such a way that containers can be steadily stacked high.

In a specific preferred embodiment of the invention, a EVA adhesive, for example Krystal Lim FDA 105, is applied to the track 2, at a temperature where the adhesive is liquid or semi-solid, but under the melting temperature for EPS. Upon use of Krystal Lim FDA 105 this will be a

temperature of about 70°C. Once the adhesive is applied, the container 1 is cooled and transported to the site of use, where fish and ice are placed into the container. When the desired contents are placed in the container, a plastic film 5, for instance a 40 μηη thick two-layer plastic film of PE and EVA, wherein the EVA layer turns towards the adhesive, is placed over the container, and guided down towards the upper side of the container, until the plastic touches the adhesive. Then the adhesive is reactivated, preferably by heat, at a temperature higher than the melting temperature for the adhesive, but lower than the melting temperature for EPS. The reactivation of the adhesive may for instance be performed by using a frame being lowered onto the plastic film and heating the adhesive through it. In cases where the adhesive is Krystal adhesive FDA 105, the frame may have a temperature of 80°C. The frame must have the same shape as the adhesive 2, but may advantageously be narrower in order to avoid direct contact between the hot frame and the EPS container.

While the adhesive is being reactivated, the film 5 is lowered further, and preferably until the film is in contact with the upper edges of the container, in such a way that it is glued to the EPS container. A container provided with such a plastic film is shown in Figure 2.

There are several machines in prior art, for fastening plastic films as lids to trays of other materials, for instance plastic trays, preferably by lamination of plastic layers. With small adjustments these machines may also be used for fastening a plastic film to a container according to.the present invention, which will be obvious to a person skilled in the art.

The savings by using plastic films 5 instead of traditional EPS lids 6, are large. A traditional lid weighs 200 gram, and a plastic film with adhesive, according to the example above, weighs about 15 g. The weight reduction per container will thus be about 185 g, and per pallet (24 containers) 24*185 g, i.e. 4,440 g. However, to ensure that a hole is not made in the lid of the uppermost containers, and to avoid loss of cold, it is preferred that the uppermost layer has traditional layers in addition, and the reduction per pallet will thus be (24-3) * 185 g = 3,840 g. The weight reduction of the containers themselves, due to new design having elevations and recesses comes in addition.

A lid adds about 2 cm to the height of a container, and the volume reduction per pallet (8 containers on top of each other) will thus be 7 * 2 cm; 14 cm. However, when the containers further are designed with elevations on the upper edge and opposite recesses on the underside of the floor, the containers can be stacked more closely than before, and the total volume reduction, having containers according to the present invention, is as shown in Figure 3, 23.9 cm, or about 230 litres. Above is shown and described a preferred embodiment of the present invention. The Figures and example are only given to illustrate an embodiment and should not under any circumstances be interpreted as limiting to the invention which is defined by the enclosed claims.