SHIPPING CONTAINER FOR SENSITIVE GOODS

Description

[0001] The invention relates to a shipping container for shipping temperature-sensitive goods, comprising container walls which surround and close off an interior space provided for receiving the goods on all sides, wherein the container walls have thermal insulation.

[0002] Conventional shipping containers for the temperature-controlled shipment of goods comprise an outer shell made of cardboard or plastic, which ensures the necessary stability during shipping and offers space for handles and inscriptions / labels. Within the outer shell is a thermal insulation layer, which may be made of Styrofoam (EPS) or another insulating material (PUR, PIR, XPS). The interior space enclosed by the container walls either contains the goods to be transported directly together with a coolant (e.g. food cooled with ice) or there is a coolant layer (e.g. ice packs with a phase change material) surrounding an inner shell in which the goods to be transported are placed. Conventional shipping containers have the problem that if the heat is applied unevenly, different local temperatures can develop within the goods to be transported.In areas with high heat input, the transported goods can therefore be heated above the maximum permissible temperature (e.g., 8°C), which by definition limits the operating time of the entire shipping box, even though significantly lower temperatures prevail in other areas. In this case, the potential of the coolant is not utilized efficiently.

[0003] A shipping container according to the preamble of claim 1 is known from JP 2012 184909 A.

[0004] This effect is particularly pronounced when the goods being transported completely fill the interior of the shipping box, thus preventing internal air circulation, which would improve heat distribution. The effect is further amplified when the coolant is located inside the goods being transported, as a large portion of the cooling energy of the internal coolant cannot be utilized.

[0005] A common approach to improving internal heat distribution is to incorporate grooves into the interior walls. This maintains air circulation even when the load is pressed against the interior walls. A disadvantage of this approach, however, is the space it requires. To achieve effective air circulation, the grooves must be at least 3-8 mm deep. This space is lost either to the interior or to the wall structure. Furthermore, differences in air density in a passively cooled container typically result in a temperature gradient within the interior. Warm air rises and causes local heating of the load. This reduces the positive effect of air circulation on heat distribution.

[0006] Another possible approach to improving internal heat distribution is the use of an inner shell made of aluminum or with aluminum elements. However, this leads to a significant increase in weight and negatively impacts the manufacturing costs and recyclability of the shipping box.

[0007] The present invention therefore aims to improve heat distribution within shipping containers.

[0008] This affects not only the heat distribution along the inner shell of the shipping container, but also within the transported goods.

[0009] The improved heat distribution should lead to an equalization of the temperature of the transported goods and any coolant throughout the entire shipping container and thus to a longer running time.

[0010] The available space within the shipping container should be utilized as efficiently as possible. The thickness of the wall structure should be minimized, and the interior should be fully loaded. Heat distribution should occur without air circulation.

[0011] Ultimately, the shipping container should be inexpensive and easy to manufacture, lightweight, and recyclable. Handling should be as simple and flexible as possible.

[0012] To achieve this object, the invention essentially provides for a shipping container of the type mentioned at the outset to have heat-conducting plates arranged in the interior and / or delimiting the interior, which heat-conducting plates are constructed in multiple layers and have at least one layer of expanded graphite.

[0013] The multilayer heat-conducting plates provided by the invention are very simple and flexible to use. On the one hand, the interior can be lined with the heat-conducting plates, creating a highly heat-conducting inner shell within the thermal insulation. On the other hand, the heat-conducting plates can be inserted as intermediate layers within the transported goods.

[0014] Expanded graphite is characterized by its low weight. Expanded graphite has high thermal conductivity, making it ideal for compensating for uneven heat input, which can occur, for example, due to thermal bridges in the container's thermal insulation. This has a positive effect on the service life of the shipping container.

[0015] Expanded graphite (also called expandable graphite) is produced by intercalating foreign components (intercalates) between the graphite lattice layers. Such expandable graphite intercalation compounds are typically produced by dispersing graphite particles in a solution containing an oxidizing agent and the guest compound to be intercalated. Commonly used oxidizing agents are nitric acid, potassium chlorate, chromic acid, potassium permanganate, and the like. Concentrated sulfuric acid, for example, is used as the intercalating compound.When heated to a temperature above the so-called onset temperature, the expandable graphite intercalation compounds are subject to a strong increase in volume with expansion factors of more than 200. This is caused by the fact that the intercalation compounds embedded in the layer structure of the graphite are decomposed by the rapid heating to this temperature with the formation of gaseous substances, whereby the graphite layers are driven apart in an accordion-like manner, i.e. the graphite particles are expanded or inflated perpendicular to the layer plane.

[0016] When fully expanded graphite is compacted under directed pressure, the graphite layer planes align preferentially perpendicular to the direction of pressure, with the individual aggregates interlocking. This allows a self-supporting layer of expanded graphite to be created without the addition of a binder.

[0017] The heat-conducting plate used according to the invention is therefore characterized in a preferred embodiment in that the layer planes of the expanded graphite run essentially parallel to one another and parallel to the plate plane. This advantageously results in an anisotropic thermal conductivity of the heat-conducting plate. This means that the thermal conductivity of the expanded graphite is high along its outer surface, but low as it passes through the material. This dual functionality leads, on the one hand, to the desired heat distribution in the plate plane and, on the other hand, to a reduction in the heat input into the transported material transverse to the plate plane. In particular, the layer of expanded graphite in the plate plane preferably has a thermal conductivity of 190-760 W / mK or 190-380 W / mK.

[0018] In order to support the possibly unstable layer of expanded graphite and to improve its handling, it is provided that the heat-conducting plates have at least one carrier layer on which the layer of expanded graphite is arranged and to which it is possibly connected.

[0019] In particular, it can be provided that the layer of expanded graphite is arranged between two carrier layers. At least one carrier layer consists of cardboard or plastic.

[0020] Preferably, the at least one carrier layer has a thickness of 0.3-1 mm. The at least one layer of expanded graphite preferably has a thickness of 0.4-4 mm, preferably 0.4-1 mm.

[0021] Due to the presence of the carrier layer(s), the thermal conductivity plate has a reduced average thermal conductivity in the plate plane compared to pure expanded graphite, which can advantageously be in a range of 60-180W / mK.

[0022] The heat-conducting plates surround the interior on all sides and without gaps. The heat-conducting plates thus form, for example, an inner shell in which the transported goods are located. In the case of a cuboid-shaped shipping container, each of the six walls is preferably assigned a heat-conducting plate, so that the aforementioned inner shell is constructed from six heat-conducting plates. The heat-conducting plates, particularly their edge areas, preferably touch each other directly, so that heat is evened out around the entire interior, whereby heat can be conducted via the inner shell, for example, from one side of the interior to an opposite side.

[0023] The heat-conducting plates can be permanently attached to the container walls. Alternatively, the heat-conducting plates can simply be applied to the container walls, whereby adjacent heat-conducting plates can be structurally connected (e.g., with interlocking) to prevent tipping into the interior. Finally, the cover plate, which is assigned to a removable container wall, i.e., a lid, is inserted. The cover plate can alternatively be attached to the lid, e.g., by adhesive.

[0024] As an alternative to arranging the heat-conducting plates on the container walls, or in addition to this, heat-conducting plates can be provided that traverse the interior of the shipping container. The heat-conducting plates can form space dividers between which the transported goods are arranged. In a preferred embodiment, the heat-conducting plates are arranged in a grid or lattice pattern and divide the interior into a plurality of cuboid-shaped receiving chambers, in each of which at least one temperature-sensitive item can be arranged, such as a medicine box or the like.

[0025] The influence of the heat-conducting plates on the service life of the shipping container is particularly significant if the shipping container has a coolant or a coolant element to which at least one of the heat-conducting plates is arranged adjacent, in particular in contact with it. A coolant element is understood here to be an element, such as a container, in which a liquid or liquefiable coolant is contained. A phase-change material can be used as the coolant, in particular. Cooling elements are designed as ice packs, for example.

[0026] Preferably, the coolant is distributed throughout the transported goods. This can be the case, for example, with medication boxes with internal cooling packs. To optimally utilize the coolant, the heat-conducting plates must be inserted both around the medication boxes and as intermediate layers. In this case, the operating time of the shipping container will be more than doubled by using the present invention. This corresponds to an increase of >100%.

[0027] Another example where the impact of heat-conducting plates is very high is incomplete coverage with cooling elements. A common problem with the use of cooling packs is that, for design reasons, a closed enclosure of the transported goods cannot be achieved. This leads to a localized heat intrusion and a premature termination of the runtime. With the use of heat-conducting plates according to the invention, the heat is evenly distributed and absorbed across the cooling packs. This leads to a significant increase in runtime.

[0028] A further preferred possibility of combining the heat-conducting plates with cooling elements can be achieved by providing an outer layer of heat-conducting plates which surround the interior on all sides, and by providing an inner layer of heat-conducting plates which surround the interior on all sides, wherein passive cooling elements are arranged between the outer and the inner layer.

[0029] The coolant can also be provided as part of the container wall. A preferred embodiment in this context provides for the container walls to be multi-layered and to have at least one layer of a coolant, such as a phase-change material, as thermal insulation.

[0030] The thermal insulation arranged in the container walls can alternatively or additionally be designed as a conventional insulation layer, with the container walls being constructed in multiple layers and having at least one thermal insulation layer as thermal insulation. The thermal insulation layer can be made, for example, of polystyrene (EPS) or another insulating material, such as polyurethane (PUR), polyisocyanurate (PIR), or extruded polystyrene (XPS). The thermal insulation layer preferably has a thermal conductivity of <0.05 W / mK, measured in a direction from the outside to the inside.

[0031] The shipping container according to the invention is preferably box-shaped. A box-shaped shipping container preferably has a cuboid-shaped base body open on one side and a lid, wherein the lid is formed integrally with the base body, e.g., connected by a folded edge, or is designed as a separate lid that can be pushed onto the base body.

[0032] Preferably, the container walls of the box-shaped shipping container are constructed of multiple layers and have an outer shell made of cardboard or plastic. A further layer of the box-shaped shipping container, arranged within the outer shell, can be formed by a thermal insulation layer. The thermal insulation layer does not have to be materially connected to the outer shell made of cardboard or plastic; rather, the thermal insulation layer can simply be inserted into the outer shell. The thermal insulation layers of the container walls can themselves form a self-supporting cuboid-shaped body that is inserted into the outer shell made of cardboard or plastic.

[0033] The shipping container according to the invention is designed especially for mail or parcel shipping and is therefore to be distinguished from a freight container or the like. The shipping container according to the invention therefore preferably has maximum dimensions of 80x50x50cm, preferably 60x50x50cm.

[0034] The invention will be explained in more detail below with reference to exemplary embodiments shown schematically in the drawing. Fig. 1 a detailed view of a heat conducting plate, Fig. 2 a cross-section through a first embodiment of a shipping container according to the invention with external heat-conducting plates, Fig. 3 a cross section through a second embodiment of a shipping container according to the invention with outer heat conducting plates and intermediate layers and Fig. 4 a cross-section through a third embodiment of a shipping container according to the invention with outer and inner heat-conducting plates.

[0035] In Fig. 1 A thermally conductive plate 1 according to the invention is schematically shown. The thermally conductive plate 1 is designed as a composite plate made of several layers. The thermally conductive plate 1 consists of two outer layers 2 made of cardboard or plastic and a layer 3 made of expanded graphite. The outer layers 2 stabilize the graphite core and each have a thickness of 0.3-1 mm. The inner graphite layer 3 has a thickness of 0.4-1 mm, resulting in a total composite thickness of 1-3 mm.

[0036] The individual layers or panels are connected by adhesive or a surrounding film (not shown).

[0037] The heat-conducting plate 1 can be manufactured in various sizes (length and width in the range 20-1000 mm) to fit the shipping container. Alternatively, the heat-conducting plates 1 can be cut to the size of the shipping container.

[0038] Fig. 2 shows a first embodiment of a shipping container according to the invention, which is designed as a cuboid-shaped shipping box. The shipping box comprises six box walls, which are formed by a lower shell or a base body 4 and a lid 5, each of which consists of an insulating material (e.g., Styrofoam) or a multi-layer wall structure. The interior space within the box walls is lined with heat-conducting plates 1, which are Fig. 1 are formed. First, the lower plate 1 is inserted. The plates 1 on the side walls are structurally connected to one another (e.g., with interlocking) to prevent tipping into the interior. Finally, the cover plate 1 is inserted. The cover plate 1 can alternatively be attached to the cover 5, e.g., by gluing.

[0039] This is the simplest version of the invention. Penetrating heat is evenly distributed across the outer inner shell made of graphite composite panels. Thermal bridges in the insulation layer are compensated.

[0040] Fig. 3 shows a second embodiment of a shipping container according to the invention, which is designed as a cuboid-shaped shipping box. The shipping box again consists of a lower shell 4 and a lid 5, each of which consists of an insulating material (e.g., Styrofoam) or a multi-layer wall structure. The interior space within the insulating layer is lined with heat-conducting plates 1, which are Fig. 1 The transported goods consist of boxes 6, each equipped with a coolant. For example, boxes with integrated phase change material can be used, as described in WO 2020 / 261104 A1 or WO 2020 / 261108 A1.

[0041] Heat-conducting plates 1 are inserted as intermediate layers between the individual layers of the transported goods. Finally, the cover plate 1 is inserted. The cover plate can alternatively be attached to the lid 5, e.g., by gluing.

[0042] Fig. 4 shows a third embodiment of a shipping container according to the invention, which is designed as a cuboid-shaped shipping box. The shipping box consists of a lower shell 4 and a lid 5, each of which consists of an insulating material (e.g., Styrofoam) or a multi-layer wall structure. The interior of the insulating layer is lined with heat-conducting plates 1, which are Fig. 1 are formed. A coolant layer 7, which consists, for example, of cooling packs, is inserted within the outer heat-conducting plates 1. This is followed by an inner layer of heat-conducting plates 1.

[0043] Although in the cross-sectional views according to Fig. 2 , 3 and4 Although only four sides of the container are shown, it is understood that the remaining two sides have the same structure.

Claims

1. Shipping container for shipping temperature-sensitive goods to be transported, comprising container walls (4, 5), which surround and close off on all sides an interior space provided for receiving the goods to be transported, whereby the container walls (4, 5) have thermal insulation and whereby heat conducting plates (1) are arranged in the interior space and / or delimiting the interior space, which heat conducting plates have a multilayer structure and comprise at least one layer (3) of expanded graphite, characterized in that the heat conducting plates (1) surround the interior space on all sides and without gaps, that the heat conducting plates (1) have at least one carrier layer (2) on which the layer (3) of expanded graphite is arranged and that the at least one carrier layer (2) consists of cardboard or plastic.

2. Shipping container according to claim 1, characterized in that the layer (3) of expanded graphite is arranged between two carrier layers (3).

3. Shipping container according to claim 1 or 2, characterized in that the at least one carrier layer (2) has a thickness of 0.3-1 mm.

4. Shipping container according to any one of claims 1 to 3, characterized in that the at least one layer (3) of expanded graphite has a thickness of 0.4-4 mm, in particular 0.4-1 mm.

5. Shipping container according to any one of claims 1 to 4, characterized in that the layer (3) of expanded graphite has a thermal conductivity of 190-760 W / mK in the plate plane.

6. Shipping container according to any one of claims 1 to 5, characterized in that the heat conducting plates (1) have a thermal conductivity of 60-180 W / mK in the plate plane.

7. Shipping container according to any one of claims 1 to 6, characterized in that the heat conducting plates (1) traverse the interior space.

8. Shipping container according to any one of claims 1 to 7, characterized in that the heat conducting plates (1) form space dividers between which the transported goods (6) are arranged.

9. Shipping container according to any one of claims 1 to 8, characterized in that the heat conducting plates (1) surround passive cooling elements, in particular coolant elements, which are arranged in the interior space of the shipping container.

10. Shipping container according to any one of claims 1 to 9, characterized in that an outer layer of heat conducting plates (1) is provided, which surround the interior space on all sides, and in that an inner layer of heat conducting plates (1) is provided, which surround the interior space on all sides, passive cooling elements, in particular coolant elements, being arranged between the outer and the inner layer.

11. Shipping container according to any one of claims 1 to 10, characterized in that the container walls (4, 5) are multilayered and have at least one layer of a coolant, such as a phase change material, as thermal insulation.

12. Shipping container according to any one of claims 1 to 11, characterized in that the container walls (4, 5) are multi-layered and have at least one thermal insulation layer as thermal insulation.

13. Shipping container according to any one of claims 1 to 12, characterized in that the container walls (4, 5) are multi-layered and have an outer shell made of a cardboard or a plastic.

14. A heat conducting plate for use in a shipping container according to any one of claims 1 to 13, comprising at least one layer (3) of expanded graphite and two carrier layers (2) between which the layer (3) of expanded graphite is disposed, characterized in that the carrier layers (2) consist of cardboard or plastic.

15. Heat conducting plate according to claim 14, characterized in that the carrier layers (2) have a thickness of 0.3-1 mm.

16. Heat conducting plate according to claim 14 or 15, characterized in that the at least one layer (3) of expanded graphite has a thickness of 0.4-4 mm, in particular 0.4-1 mm.