NO20170055A1

NO20170055A1 - Container for transportation and storage of foods

Info

Publication number: NO20170055A1
Application number: NO20170055A
Authority: NO
Inventors: Torbjørn Grimstad; Hrafn Stefansson
Original assignee: Bra Kasser As
Priority date: 2017-01-13
Filing date: 2017-01-13
Publication date: 2018-07-16
Also published as: NO343823B1

Abstract

The invention concerns a container (1) made of expanded synthetic plastic material for transport and/or storage of foods. The container comprises: - a base (3) having an inner surface (30 and an outer surface (3"), - at least one sidewall (2) fixed to the base's (3) circumference (5), the sidewall having an inner surface (20 and an Outer surface (2"), and wherein the base (3) has a maximum thickness in its centerarea (4) seen perpendicularly from above which is larger than the thickness of the base (3) closer to its circumference (5), and wherein the center area includes the center point of the base and covers a base surface area up to 40% of the total base surface area. The inventions also concerns a lid for the container and a method for producing such a container.The invention concerns a container (1) made of expanded synthetic plastic material for transport and / or storage of foods. The container comprises: - a base (3) having an inner surface (30 and an outer surface (3 ")) - at least one sidewall (2) fixed to the base's (3) circumference (5), the sidewall having an inner surface (20 and an Outer surface (2 "), and the base (3) has a maximum thickness in its center area (4) seen perpendicularly from above which is greater than the thickness of the base (3) closer to its circumference) 5), and including the center area includes the center point of the base and covers a base surface area up to 40% of the total base surface area.The inventions also concern a lid for the container and a method for producing such a container.

Description

Technical Field:

The present invention relates to a synthetic plastic container for transportation and storage of foods and a method for producing such container.

Background and prior art:

Traditional containers are known for transporting and/or storage of foods such as fish. Expanded Polystyrene (EPS) is one of the most common materials used in such containers, providing light and hygienic containers having very good isolation properties. To keep the fish fresh during transportation and/or storage, the fish is placed inside the container together with a sufficient amount of ice. Also other cooling methods can be used such as super cooled saltwater in sealed plastic bags. The containers are closed with a lid of EPS-material and strapped. The conventional containers are normally rectangular in shape and stacked on top of each other during transportation. The containers can be placed on EUR-pallets for transportation. Normally, three stacks of containers, each stack comprising up to nine containers are placed on one EUR-pallet (standard European pallet). A detailed description of a relevant prior art is presented in WO 2011/062502 A1 and GB 987850.

WO 2011/062502 A1 shows a traditional container of EPS for transportation and/or storage of fish.

GB 987850 shows a container for fish of rectangular shape, wherein the container has a base curved upwards towards the top of the container for the purpose of collecting liquids from the fish and cooling ice to flow out through slits.

A disadvantage with the containers known from prior art is that they are weak, thus often breaking during transportation and handling. During transportation the container are stacked on top of each other. Thus, the containers positioned at the bottom of a stack have a tendency to brake during transportation, thus wasting/compromising the food contents within the containers.

Thus, it is an object of the present invention to provide a container for transportation and storage of food such as fish that at least mitigate the above mentioned disadvantages, i.e. to provide a container having an improved mechanical strength, and consequently a load carrying capacity and an impact strength able to withstand the dynamic and static pressure typical containers containing fish may be exposed to during transportation., thereby increasing the number of containers that may be stacked on top of each other without breaking.

Another object of the present invention is to provide a container having improved isolation properties.

Yet another object of the present invention is to provide lighter containers thereby inter alia ease the total handling weight for personnel when handling fish containers.

Yet another object of the present invention is to optimize and reduce the cost related to the manufacturing of the containers.

Yet another object of the present invention to provide a lid for covering the above inventive container having an increased mechanical strength compared to a traditional lid of same circumferential size and weight.

Yet another object of the present invention to provide a container having an outer/external volume typical for a traditional container containing fish, and where the inventive container shows a higher mechanical strength with no or a minimum of storage capacity loss inside the container.

Summary of the invention:

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention.

In particular, the invention concerns a container made of expanded synthetic plastic material for transportation and/or storage of fish. However, the inventive container may also be used for other food products.

The container comprises:

- a base having an inner surface and an outer surface,

- at least one sidewall fixed to the base’s circumference, the sidewall having an inner surface and an outer surface,

and wherein the base has a maximum thickness in its center area seen perpendicularly from above which is larger than the thickness of the base closer to its circumference, wherein the center area includes the center point of the base and covers a base surface area up to 40% of the total base surface area.

The container is made of expanded synthetic plastic material which can be selected from polystyrene, polyethylene or polypropylene or any food contact approved polymer.

The inner surfaces of the container should be understood as the surface facing the inside of the container, while the outer surfaces of the container should be understood as the surface facing the outside of the container.

The container may be of any geometrical shape like for example a cylinder having a round base and one sidewall enclosing the circumference of the base, or a cuboid having a rectangular base (such as squared) and four sidewalls enclosing the circumference of the base. In an advantageous embodiment of the invention, the container comprises a rectangular base and four sidewalls, but where the container deviate from a cuboid form in that two parallel sidewalls are longer than the two other parallel sidewalls.

Traditional rectangular containers having a uniform base wall thickness over the whole base area will unavoidably have the weakest area in the center point of the container’s base.

An increased thickness at the center area which includes the center point of the container’s base provides an increased strength in the container which is important in order to avoid damages to the containers during loading and transportation. The increased thickness also results in increased isolation properties.

If the container’s base is symmetrical, the center point of the container base is defined as the point on the inner surface of the base left unchanged by symmetric actions. Hence, the center point of a base having the form of a square, rectangle, rhombus or parallelogram is where the diagonals intersects, this being the fixed point of rotational symmetries. Similarly, if the base has the form of a circle, the center is the point equidistant from the points on the edge / circumference.

According to the present invention, the term “center area” of the base is used to define an area of the base which includes the center point as defined above and covers a base surface area up to 40 % of the total base surface area.

In a preferred embodiment according to the present invention, the center area covers up to 30 % of the base surface area, more preferably up to 20 % of the surface area, and even more preferably up to 10 % of the surface area. The center area may cover an area as small as the center point as defined above of the base surface area.

In another advantageous embodiment, the thickness of the center area of the base of the container is at least 2 % thicker than the thickness at or adjacent to the base’s circumference. Preferably, the center area of the base is more than 10 % thicker, and even more preferably more than 20 % thicker, and even more preferably more than 30 % thicker than the thickness at or adjacent to the circumference of the base.

In another advantageous embodiment the base of the container has a minimum thickness at or adjacent to the base’s circumference.

In another advantageous embodiment the inner surface of the base of the container has a dome shaped structure, where the outer surface of the base is flat relative to the inner surface of the base.

Further, the container according to the present invention may in an advantageous embodiment comprise at least one curved crossing between the base’s inner surface and the at least one sidewall’s inner surface.

In another advantageous embodiment the area at the crossing between the base’s inner surface and at least one sidewall’s inner surface has a varying radius. When replacing the constant small radius in traditional rectangular containers with variable and much bigger radius as in the present invention, the strength of the container increases.

The increased thickness of the crossings due to the curving of the crossings contribute and/or the avoidance of any sharp edges further increase the mechanical strength of the container. Thus, the crossings are having a bigger inner surface radius than traditional rectangular containers having crossings that are not curved but close to 90°.

The term “crossing” should be understood as an edge wherein one sidewall meets another sidewall, wherein one sidewall meets the base or wherein the edge of two sidewalls meet the base of the container. The latter crossing is referred to as a corner of the container.

The term “curved” should be understood as the crossings or corners being rounded by an arc of a circle arranged on the inside of the container, and wherein the radius of the circle is in the range from 5 mm to 80 mm, preferably between 10 mm and 70 mm, more preferably between 15 mm and 60 mm. Hereinafter, the radius of the curved crossing is referred to as “radius”.

In addition to increased strength of the container, the benefits of rounded or curved crossing is related to an increased production rate of the containers. The mold used during production of the containers will have a structure corresponding to the shape to the container. Thus the corners at the inside of the mold will be curved, resulting in an increased flow rate of the EPS-material during filling compared to filling of a mold having 90<o>corners. When the corners or crossings inside the mold are not curved the velocity of the flow of EPS-material inside the mold decreases significantly when traversing the sharp corners. The time of filling of EPS-material in the mold is hence longer compared to molds with curved crossings. The curved corners or crossings of the mold causes a more efficient flow inside the mold since the velocity of the flow does not decrease significantly during transverse. The time of filling of the mold is thus faster and the production rate increases.

As is known practice in all mold making industries, the sidewalls of the produced containers are usually slightly tapered, by as little as 0.5° and up 2° to ease the ejection of the container out from the mold.

Strength analysis of traditional container have shown that the sidewalls often crack adjacent to or at the crossing between the sidewalls and the base of the container. The sidewall pressure from the goods inside the container also increases towards the base of the container. An increased wall thickness is therefore needed at or adjacent to the crossing between the sidewalls and the base of the container.

In another embodiment of the invention the outer surface of at least one of the sidewalls is straight and facing perpendicular to the outer surface of the base, and the inner surface of said at least one wall is straight and wedged towards the inner surface of the base such that the thickness of said at least one sidewall is at its thickest close to the base.

The thickness of the wedged sidewall close or at the base of the container is preferably at least 3 % thicker than the thickness of the sidewall close or at the top of the container, more preferably the thickness close or at to the base is at least 10 % thicker, and even more preferably at least 30% thicker than the thickness at the top of the sidewall.

In another advantageous embodiment the container has four sidewalls.

In another advantageous embodiment, wherein the container has four sidewalls, the area at the crossing between the base’s inner surface and at least one sidewall’s inner surface comprises a varying radius wherein the radius of the crossing gradually increases being smallest at or adjacent to the corners and largest halfway between two corners.

In another advantageous embodiment wherein the container has four sidewalls, the at least one crossing between the inner surfaces of two sidewalls of the container is curved. In a preferred embodiment radius of the crossing between two sidewalls is larger at or adjacent to the base of the container than the radius of the crossing closer to the top of the container.

In another advantageous embodiment wherein the container has four sidewalls, the crossing between the outer surfaces of at least two sidewalls of the container are curved.

In another preferred embodiment wherein the container has four sidewalls, all the crossing on the inside of the container are curved meaning that all the crossings between the inner surfaces of two sidewalls are curved and all crossings between the inner surface of the sidewalls and the inner surface of the base are curved. It is also preferred that all the crossings between the outer surfaces off two sidewalls are curved.

Also the base corners or crossings on the inside of a container, having four sidewalls, are preferably curved, meaning that the crossing wherein the inner surface of the base meets the inner surfaces of two sidewalls are curved.

Further, the crossings wherein the outer surface of the sidewalls meet the outer surface of the base may also be curved, but preferably these crossings are approximately 90° so the box can be easily palletized.

The larger the radius is in a crossing, the larger is the thickness at the crossing of the container, which again results in an increased strength of the container. By varying the radius of the crossings, the thicknesses of the crossings in the container is increased where the container is weakest.

In another embodiment wherein the container has four sidewalls, the outer surfaces of the sidewalls are straight facing close to perpendicular to the outer surface of the base, and the inner surfaces of at least one sidewall is straight and wedged towards the inner surface of the base such that the thickness of said at least one sidewall is at its thickest close to the base. In a preferred embodiment, all the sidewalls of said container comprises such a wedged shaped inner surface of the sidewalls.

The increased thickness of the walls towards the base provides thicker and stronger crossings between the at least one sidewalls and the base of the container. Further, if the container has four sidewalls, there will also be an increased thickness at the base at each crossing of two sidewalls. The increased thickness provides increased strength in the container and minimizes the chances of the container being damaged or breaking during loading and/or transportation when compared to traditional containers known from prior art.

The container may also comprise through going drain holes/slits located at the base at each crossing of two sidewalls. The through going drain holes/slits allows melted ice (water) and other liquids to escape from the inside to the outside of the container.

Further, the container may comprise handles. In a four walled container, the handles can be located on the outer surface of two sidewalls.

The present invention also concerns a lid for covering containers as described above.

The lid is preferably made of the same expanded synthetic plastic material as the container and comprises an inner and outer surface wherein the inner surface of the lid has a maximum thickness in its center area seen perpendicularly from above which is larger than the thickness closer to the circumference of the lid, wherein the center area includes the center point of the inner surface area and covers a inner surface area up to 40% of the total inner surface area.

The inner surfaces of the lid should be understood as the surface facing the inside of the container during use.

The lid may be of any geometrical shape like for example a circular or rectangular depending on the geometry of the container. In an advantageous embodiment of the invention wherein the container is rectangular, the lid is rectangular having two parallel edges that are longer than the two other parallel edges.

As for the container, if the surface area of the lid is symmetrical, the center point of the lid’s inner surface area is defined as the point on the inner surface left unchanged by symmetric actions. Hence, the center point of a inner surface area having the form of a square, rectangle, rhombus or parallelogram is where the diagonals intersects, this being the fixed point of rotational symmetries. Similarly, if the surface area has the form of a circle, the center is the point equidistant from the points on the edge / circumference.

According to the present invention, the term “center area” of the inner surface area is used to define an area of the inner surface which includes the center point as defined above and covers a inner surface area up to 40 % of the total inner surface area.

In a preferred embodiment according to the present invention, the center area covers up to 30 % of the total inner surface area, more preferably up to 20 % of the inner surface area, and even more preferably up to 10 % of the inner surface area. The center area may cover an area as small as the center point as defined above of the total inner surface area.

In an advantageous embodiment the maximum thickness of the center area of the inner surface of lid is at least 2 % thicker than the thickness at, or adjacent to, the lid’s circumference. Preferably, the center area of the inner surface is more than 10 % thicker, and even more preferably more than 20 % thicker than the thickness at or adjacent to the circumference of the inner surface.

In another advantageous embodiment the inner surface of the lid has a dome shaped structure and the outer surface is flat relative to the inner surface.

An increased thickness in the center area of the lid increases the strength of the lid. It may thus withstand stronger impacts or strain compared to conventional lids, i.e. lids not having an increased thickness at the center area.

The inventions also concerns an assembly for transportation and/or storage of food comprising a container and a lid,

wherein the container comprises a base having an inner surface and an outer surface, wherein the base has a maximum thickness in its base center area seen perpendicularly from above which is larger than the thickness of the base closer to its circumference, and wherein the base center area includes the center point of the base and covers a base surface area up to 40% of the total base surface area, and at least one sidewall fixed to the base’s circumference, the sidewall having an inner surface and an outer surface, and

wherein the lid has an inner surface with a maximum thickness at its center area seen perpendicularly from above which is larger than the thickness of the inner surface area closer to its circumference, and wherein the center area includes the center point of the inner surface area and covers a surface area up to 40% of the total inner surface area.

When the assembly comprising the container and lid is closed, plastic straps are applied to keep the assembly closed during transportation. The straps have a tendency to make cuts into the outer surface of the lid thus making it weaker. Hence, the lid is preferably further strengthened with areas having increased thickness, i.e. with more EPS-material, so that the lids will be able to withstand the pressure and avoid cuts from the straps. This is particularly important at the edges of the lid.

The invention also concerns a method for manufacturing a container. The method comprises the following steps:

- feeding beads of pre-expanded synthetic plastic material through at least one inlet channel into a closed mold, wherein the mold has a shape corresponding to the shape of the container as described in any of the features above,

- molding the pre-expanded beads with steam and pressure, causing the beads to fuse together,

- cooling the mold, and

- removing the container from the mold.

The cooling can for example be achieved by vacuum and/or spray cooling.

A person skilled in the art will be familiar with the process of molding containers made of EPS-materials. The method described above is a conventional method, but the shape of the mold is different from the conventional molds for producing such containers. Due to the above described curved crossings or corners inside the mold, the shape of the mold according to the present invention leads to an increased production rate of containers.

According to the invention more material in volume is needed to produce a container having such an increased thickness in the base and thus more material in volume is needed to fill the mold during production compared to traditional containers for storing and transporting fish. Accordingly one could think the time saved due to the curved corners in the mold would outweigh the time it takes to fill the mold with a bigger volume of EPS-material, but this is not the fact for the present invention. The time saved due to the curved crossings inside the mold is longer than the time it takes to fill the mold with the extra volume of EPS-material, thus the production is more efficient than the conventional method which comprises a conventionally shaped mold having none or less curved crossings / corners.

The density of the EPS-material used in the traditional containers can be reduced in containers according to the present invention while still obtaining higher strength due to their different shape.

In the following description, numerous specific details are introduced to provide a thorough understanding of embodiments of the claimed container, lid, assembly and method. One skilled in the relevant art, however, will recognize that these embodiments can be practiced without one or more of the specific details, or with other components etc. In other instances, well-known structures or operations are not shown, or are not described in detail, to avoid obscuring aspects of the disclosed embodiments.

Brief description of the drawings:

Fig. 1 shows perspective view of a container according to prior art.

Fig. 2 (a) shows a container according to prior art seen perpendicularly from above, fig. 2 (b) shows a cross sectional side view along section A-A shown in fig. 2 (a) and fig. 2 (c) shows a cross sectional side view along section B-B shown in fig. 2 (a).

Fig. 3 shows a perspective view of a container according to the present invention.

Fig. 4 shows the container in fig. 3 seen perpendicularly from above.

Fig. 5 shows a cross sectional side view of the container along section A-A shown in fig. 4.

Fig. 6 shows a cross sectional side view of the container along section B-B shown in fig. 4.

Fig. 7 shows the outer surface of a lid according to the present invention seen perpendicularly from above.

Fig. 8 (a) shows a cross sectional side view of the lid along section C-C in figure 7 and fig 8 (b) shows a cross sectional side view along section D-D in figure 7.

Detailed description of the invention

Fig. 1 and 2 show a traditional container 1 according to prior art.

Fig. 1 shows a traditional container 1 which is rectangular and comprises four sidewalls 2 and a base 3. The sidewalls 2 comprise an inner surface 2’ and an outer surface 2’’ that are planar in shape. Also the base 3 comprises an inner surface 3’ and an outer surface 3’’ that are planar in shape.

Further, it can be seen that the crossings 6’ between the outer surfaces 2’’ of two sidewalls 2 are approximately 90°, the crossings 6 between the inner surfaces 2’ of two sidewalls 2 are approximately 90°, and the crossings 6’ between the inner surfaces 2’ of the sidewalls 2 and the inner surface 3’ of the base 3 are approximately 90°. Also the four base corners 6’’‘ on the inside of the container 1, wherein the drain holes 7 are located, are also approximately 90°.

Fig. 2 (a), (b) and (c) shows different views of the traditional container 1 in fig. 1. Fig. 2 (a) shows the container 1 seen perpendicularly from above. Drain holes 7 are shown in each base corner 6’’’ between two sidewalls 2. The crossing 6 between the inner surfaces 2’ of two sidewalls 2 is seen to be approximately 90°, and the crossings 6’ between the outer surfaces 2’’ of two sidewalls 2 is seen to be approximately 90°. Also the crossing 6’’ between the inner surface 3’ of the base 3 and an inner surface 2’ of a sidewall 2 is seen to be approximately 90°. Fig. 2 (b) shows a cross sectional side view of section A-A indicated by arrows in fig. 2 (a) and fig 2 (c) shows a cross sectional side view of section B-B also indicated by arrows in fig. 2 (a). As can be seen from both the cross sectional views of this container 1 the base 3 has a uniform thickness over the entire base 3.

For a four side rectangular container, the distance between the parallel, vertical sidewalls and the size of the radius between the base’s inner surface and the sidewalls may play a big role in optimizing the thickness of the base towards and at the center area. Such optimization depends on the strength requirements and design of the container.

Fig. 3 shows a container 1 according to the present invention. As can be seen, the container 1 comprises curved crossings 6, 6’ where two sidewalls 2 meet both on the inner surface 2’ and outer surface 2’’ of the sidewalls 2. Further it can be seen that the crossing 6’’ where the inner surface 3’ of the base 3 of the container 1 meet the inner surface 2’ of the wall 2 is curved having a variating radius.

Further, at the corners of the container 1, where the base 3 meets two sidewalls 2 at the crossing 6’’’, drain holes 7 are shown.

The outer surface 2’’ of the at least one wall 2 may be partly provided with a hollow part of preferably a rectangular or trapezoidal shape extending from the base 3 of the container 1 to provide a hand grip/handle 8. Such hand grips 8 should be well known to a person skilled in the art and is also illustrated in fig. 1.

Fig. 4 show a top view of the container 1 shown in fig. 3. Fig. 4 illustrates the inner surface 3’ of the base 3 showing the center area 4 of the container 1. The center area 4 is the area at base 3 covering at least the area where line B-B meets line A-A, also called center point. As indicated by the oval circles on the figure, the thickness of the base 3 increases from the circumference 5 towards the center area 4 of the base 3 of the container 1, in the similar way that terrain heights are shown in topographic maps. The smaller the oval circles are, the thicker is the base 3 of the container 1.

As also illustrated in the fig. 4, the crossings 6’’ between the sidewalls 2 and the inner surface 3’ of the base 3 are curved having a varying radius. The radius of the curved crossing 6’’ is at its smallest close to the corners 6’’’ and at its largest in the halfway between two corners 6’’’. Thus, the thickness between the inner surface and outer surface of the container 1 at the crossing 6’’ is at its largest halfway between two corners 6’’’.

Also fig. 5 and 6 show the inventive container 1 shown in fig. 3 and 4. Fig. 5 shows the cross sectional side view of section A-A in fig. 4 and fig. 6 shows the cross sectional side view of section B-B in fig. 4. Both figures displays how the thickness of the base 3 of container 1 increases form the circumference 5, 6’’ towards the center area 4 of the inner surface 3’ of the base 3.

The inner surface 2’ of the walls 2 are straight and wedged towards the inner surface 3’ of the base 3 such that the thickness of the sidewalls 2 are at their thickest close to the base 3. The crossings 6’’ wherein the inner surface 3’ of the base 3 meets the inner surface 2’ of the sidewall 2 is curved giving an increased thickness in the crossing 6’’ of the container 1.

Fig. 7 (a) shows a top view of the inner surface 8’ of a lid 8 according to the present invention. The oval circles indicate how the thickness of the inner surface 8’ of the lid 8 increases towards the center area 9. The smaller the circumference of the oval circle, the thicker is the inner surface 8’ of the lid 8.

Fig. 7 (b) shows a top view of the outer surface 8’’ of a lid 8 according to the present invention. As can be seen form the figure, the lid 8 has strengthening areas 11 placed wherein the plastic straps are applied when sealing the container 1. The outer surface 8’’ of the lid 8 is substantially straight with the exceptions of the strengthening areas. Further the center area 9 is shown on the figure.

Fig. 8 (a) shows a cross sectional side view of section C-C in fig. 7. Fig 8 (b) shows the cross sectional side view of section D-D in fig. 7. Both figures, 8 (a) and 8 (b) displays how the thickness increases form the circumference towards the center area 9 of the inner surface 8’ of the lid 8. The figure also illustrates the strengthening areas 11 placed wherein the plastic straps are applied when sealing the container 1 comprising the lid.

Illustrating example:

The present example illustrates the differences between a fish container according to the present invention and traditional fish containers. In the example the container of the present invention and the traditional container have the same external volume, meaning that they have the same length, height and width being approximately 800 mm long, 400 mm wide and 200mm high.

The container according to the present invention is made by feeding beads of preexpanded polystyrene into a closed mold through three inlet channels. The mold has the shape corresponding to the shape of the inventive container and the preexpanded beads may have a density of about 20-25 kg/m<3>. After molding the preexpanded beads with steam at about 115 °C and pressure of about 0.9 bar causing the beads to fuse together, the molded container is cooled with vacuum. The containers produced have a density of about 17 kg/m<3>of expanded polystyrene.

Thus, the containers produced by the present method have a lower final density, about 17 kg/m<3>, when compared to traditional containers which have a final density of about 20-25 kg/m<3>.

The thicker base and sidewalls of the container according to the present invention causes a higher volume of material needed to produce the inventive containers compared to traditional containers. Nevertheless, the present example shows that even if the total volume of material needed to produce the inventive containers are higher than for traditional containers, still less material is needed to produce the inventive containers due to the lower density of the material of the inventive containers compared to traditional containers. Further, even if the inventive containers have a lower density, the impact strength and strain of the containers produced are proven to be better and higher than traditional containers due to the increased thickness in the base, walls and crossings. The low density of the material of the inventive containers also makes the inventive containers lighter than traditional containers.

In traditional containers about 4 kg of ice is needed per container for storage and transportation of fish for a given period of time. The inventors have found that the inventive containers having thicker base and sidewalls than traditional containers, and further comprises a density of about 17 kg/m<3>only needs 3 kg of ice per container for storage and transportation of fish to provide the same cooling effect as traditional containers for the same given period of time. Thus, the isolation properties of the inventive container is much higher when compared to traditional containers. Further, the volume inside the inventive container which is lost due to the thicker base and walls does not influence the amount of fish to be transported or stored in each container since less ice is needed. The reduced amount of ice needed is thus at least corresponding to the loss of volume inside the container due to the thicker base and walls.

The increased impact strength and strain of the container according to the present invention causing increased resistance for the containers to break, also renders it possible to stack a bigger amount of containers on top of each other and avoiding that the containers situated at or close to the bottom of the stack to break during transportation.

Traditional containers are normally stacked on EUR-pallets during transportation. One EUR-pallet (which is 120cm x 80 cm 14.4 cm) takes 3 stacks of containers wherein each stack comprises 9 traditional containers, thus the total amount of traditional containers per EUR-pallet is 27.

By substituting the traditional containers with containers according to the present invention, each stack of containers can comprise 11 containers, thus each EUR-pallet can take 33 containers. Thus, the present invention provides a decrease in transportation costs in that a bigger amount of containers can be transported simultaneously when compared to traditional containers. The more containers that can be transported at the time, the more food/fish can be transported. Further the risk of the containers breaking during loading or transportation is significantly reduced.

In the preceding description, various aspects of the container and lid according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the container. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the container, which are apparent to persons skilled in the art to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention.

List of reference numerals / letters:

1 container

2 sidewall of the container

2’ inner surface of the sidewall

2’’ outer surface of the sidewall

3 base of the container

3’ inner surface of the base

3’’ outer surface of the base

4 center area of the base of the container

5 circumference of the base of the container

6 crossing between the inner surfaces of two sidewalls

6’ crossing between the outer surfaces of two sidewalls

6’’ crossing between the inner surface of a sidewall and the inner surface of the base

6’’’ base corners, crossing at the base where two sidewalls meet each other and the base

7 drain holes

8 lid

8’ inner surface of the lid

8’’ outer surface of the lid

9 center area of the lid

10 circumference of the lid

11 strengthening area

Claims

1. A container (1) made of expanded synthetic plastic material for transport and/or storage of fish, comprising

- a base (3) having an inner surface (3’) and an outer surface (3’’),

- at least one sidewall (2) fixed to the base’s (3) circumference (5), the sidewall having an inner surface (2’) and an outer surface (2’’),

characterized in that the base (3) has a maximum thickness in its center area (4) seen perpendicularly from above which is larger than the thickness of the base (3) closer to its circumference (5), and wherein the center area includes the center point of the base and covers a base surface area up to 40% of the total base surface area.

2. The container (1) in accordance with claim 1, characterized in that the thickness of the center area (4) of the base (3) is at least 2% thicker than the thickness at, or adjacent to, the base’s circumference (5).

3. The container (1) in accordance with any one of the preceding claims, characterized in that the inner surface (3’) of the base (3) has a dome shaped structure and the outer surface (3’’) is flat relative to the inner surface (3’).

4. The container (1) in accordance with any one of the preceding claims, characterized in that the area at the crossing between the base’s inner surface (3’) and the at least one sidewall’s inner surface

is curved.

5. The container (1) in accordance with any one of the preceding claims, characterized in that container comprises four sidewalls (2) and wherein the base (3) of the container (1) is rectangular.

6. The container (1) in accordance with claim 5, characterized in that the container (1) has:

- curved crossings (6,) between the inner surfaces

of two sidewalls (2),

- curved crossings (6’’) between the outer surfaces (2’’) of two sidewalls (2), and

- curved crossings (6’) between the inner surface

of the sidewalls (2) and the inner surface (3’) of the base (3).

7. The container (1) in accordance with claim 5 or 6, characterized in that the outer surface (2’’) of at least one of the walls (2) is straight and facing perpendicular to the outer surface (3’’) of the base (3), and the inner surface

of said at least one wall (2) is straight and wedged towards the inner surface (3’) of the base (3) such that the thickness of said at least one wall (2) is at its thickest close to the base (3).

8. The container (1) in accordance with any one of claims 5 to 7, characterized in that it comprises through going drain holes (7) located in the base (3) at each crossing (6’’’) of two sidewalls (2).

9. The container (1) in accordance with any of the preceding claims, characterized in that the synthetic plastic material is selected from polystyrene, polyethylene or polypropylene.

10. A lid (8) made of expanded synthetic plastic material for sealing a container (1) according to any one of claims 1-9 characterized in that a inner surface

of the lid (8) has a maximum thickness in its center area (9) seen perpendicularly from above which is larger than the thickness of the lid (8) closer to its circumference (10), wherein the center area includes the center point of the inner surface area and covers a surface area up to 40% of the total base surface area.

11. The lid (8) in accordance with claim 10, characterized in that the maximum thickness of the center area (9) of the inner surface (8’) of the lid (8) is at least 2% thicker than the thickness at, or adjacent to, the lid’s circumference (10).

12. The lid (8) according to claim 10 or 11 characterized in that the inner surface (8’) has a dome shaped structure and a outer surface (8’’) is flat relative to the inner surface (8’).

13. The lid (8) according to any one of claims 10-12 characterized in that the lid (8) is made of a synthetic plastic material selected from polystyrene, polyethylene or polypropylene.

14. An assembly for transport and/or storage of fish characterized by comprising

- a container (1) in accordance with any of claims 1-9, and

- a lid (8) in accordance with any one of claims 10-13.

15. A method for manufacturing a container (1), characterized by comprising the following steps:

- feeding beads of pre-expanded synthetic plastic material into a closed mold through at least one inlet channel, wherein the mold has a shape corresponding to the shape of the container (1) according to any one of claims 1-9,

- molding the pre-expanded beads with steam and pressure, causing the beads to expand and fuse together,

- cooling the mold, and

- removing the container (1) from the mold.

17. Use of a container according to any one of claims 1-9 for storage and transportation of food.