EP3368841B1 - Method for producing a diffusing sheet of cork, diffusing cork wall, and isothermic container comprising such a wall - Google Patents

Description

Field of the invention

The invention relates to a method of manufacturing a cork diffusing plate for an insulated container, to a cork diffusing plate and to an insulated container comprising such a plate for containing pharmaceuticals, foodstuffs or any other type of object. asking to be transported at a controlled temperature.

State of the art

Various insulated containers are currently known. The insulated containers allow their contents to be kept at a certain desired temperature, in order to keep them at a controlled temperature during their transport or storage.

The document US 2002/0050147 discloses an insulated container comprising a double plastic wall inside which are placed heating or cooling elements. This double wall comprising the heating or cooling elements defines a volume which is used as a container. The container will be kept at a certain temperature depending on the content. Thanks to this type of container, the objects are not in direct contact with the heating or cooling elements.

In the container of the prior art, the internal walls of the double wall are made of plastic and are less insulating than the external walls, so that the heat flux is transmitted to the container, and not to the outside. The problem is that the temperature of the cooling or heating elements is transmitted quickly to the container through the plastic walls, this can create a thermal shock for the objects contained. This thermal shock is a problem for foods for example, for which sudden temperature change is not recommended. In addition, when the cooling elements transmit their temperature to the container and heat up, condensation is created and moisture is found on the plastic walls.

The document CH 147246 A discloses a thermally insulating container whose walls are made using several layers of cork, with air spaces between the layers of cork filled with raw granules of cork.

Summary of the invention

An object of the invention is first to provide a method of manufacturing a diffusing plate for an insulated container, making it possible to avoid thermal shocks by ensuring a spread over time of the temperature through this plate.

To this end, the invention relates to a method of manufacturing a cork diffusing plate for an insulated container. Considering a starting cork plate of initial density, it is compressed to laterally increase the density, form crusted outer skins with a diffusion greater than that initial and thus control the diffusion of the compressed plate.

Thanks to the method of the invention, a cork diffusing plate is obtained with its outer skins of higher density than the internal part, which gives a diffusing property to the external surfaces and an insulating property to the internal part of the plate. This conformation of the plate therefore makes it possible to have diffusing and insulating power at the same time, thanks to the diffusing power of external crusts and to the insulating power of the internal alveolar part. The result obtained is that the plate thus produced offers a control of the diffusion of the temperature through it. In addition, the external crusts provide rigidity to the plate, which allows it to be machined precisely, and assembled to hold it in the container. This rigidity provided by the crusts is essential, otherwise the plates should be much thicker and the useful volume of the container would be greatly reduced.

The invention further relates to a cork diffusing plate for an insulated container produced according to the manufacturing method of the invention.

The invention also proposes a type of insulated container comprising walls, said walls comprising an external cork plate and an internal cork plate, with an intermediate space arranged to receive a thermal source, the walls being arranged to receive content, characterized in that said internal plate is a cork diffusing plate produced according to said manufacturing process.

The internal plate of the wall is the diffusing plate of the invention, compressed so as to have a particular structure having a higher density of its external surfaces. This internal wall thus improved makes it possible to diffuse over time the temperature from the thermal source to the volume capable of receiving content which must be kept at a certain temperature. The heat source can of course be a cold source or hot. Depending on the thickness of the sublayers in the internal plate and the densities of these sublayers, the temperature spreads more or less quickly. This results in being able to manage the broadcasting time, depending for example on the transport time of the content to be kept under controlled temperature. The temperature is controlled thanks to this diffusing plate. On the other hand, the outer plate has a lower density than the inner plate, in order to force the heat flow to go towards the volume intended to receive the content, and not towards the outside of the container. The difference in density between the external and internal plate coupled to the multi-density system of the internal plate makes it possible to optimize the desired effect.

Another advantage is that the thermal shocks experienced by the containers of the prior art are avoided. The temperature will diffuse slowly through this internal plate, so as not to suddenly change the temperature of the volume intended to receive the content. The distribution of cold or hot is controlled in advance thanks to the thickness of the compressed cork underlayments of the internal plate.

Another breakthrough observed is that cork is a moisture-absorbing material. When the cold heat source heats up and condenses, the condensation will be absorbed by the outer plate. Indeed, the outer plate is less dense than the inner plate, which promotes the absorption of moisture by this outer plate. In addition, the dense crust of the inner wall also promotes this absorption of moisture by this outer plate, because this crust acts as a barrier to moisture.

On the other hand, the central part of the internal plate of the wall makes it possible to store cold or hot, which must pass through the two external crusts. The internal plate will therefore charge in order to become itself a reserve of hot or cold. We can therefore keep hot or cold more stable if the container is opened for a brief manipulation.
Also, the internal plate loading uniformly over its height and width is then assimilated to an element allowing a perfectly homogeneous diffusion of the desired temperature and not a point source.

These three claimed means of the invention proceed from the same inventive concept closely linked to the diffusing plate, as such, and its manufacturing process.

Brief description of the figures

• La Figure 1 est une vue en coupe de la plaque diffusante en liège comprimé de l'invention;
• La Figure 2 est une vue du dessus du conteneur isotherme de l'invention ;
• Et la figure 3 est une vue en perspective du conteneur de la figure 2.

These and other aspects of the invention will be clarified by the detailed description of the invention, reference being made to the accompanying drawings, in which:

• The Figure 1 is a sectional view of the compressed cork diffusing plate of the invention;
• The Figure 2 is a top view of the insulated container of the invention;
• And the figure 3 is a perspective view of the container of the figure 2 .

Figures are not drawn to scale. Similar elements are denoted by similar references in the figures.

Detailed description of particular embodiments

With reference to the figure 1 , a starting cork plate has been compressed on the surface to a determined thickness, and so as to have a density varying on the section of the plate 1. The density within said plate 1 is higher on the external surfaces 2 than in the internal part 3 of said plate 1 to allow control of the diffusion of the temperature through said plate.

During this manufacturing process, said starting cork plate is here compressed over its entire surface.

The external surfaces 2 are assimilated to dense crusts, having a density between 0.6 to 0.85, while the internal part 3 of the diffusing wall 1 has a honeycomb structure with a density between 0.15 and 0.45. The cellular inner part 3 therefore has a higher insulating power than the outer crusts 2. This conformation of plate 1 makes it possible to have a diffusing and insulating power at the same time, thanks to the diffusing power of the outer crusts 2 and the insulating power of the internal alveolar part 3.

A determined proportion between the thicknesses of the dense external crusts 2 and the internal alveolar part 3 must be obtained. It is the same for the ratio between the densities of these two parts. The proportion of internal alveolar part 3 must not be too high, at the risk that the plate 1 is too insulating and that the temperature diffusion through it is too slowly. On the contrary, the proportion of external crusts 2 must not be too high either, at the risk that the plate 1 is not sufficiently insulating and that the temperature diffusion through it takes place too quickly.

The dense external crusts 2 also provide adequate rigidity to the plate in order to give it its retention in the container 4. To achieve ideal insulation, the cork plate 1 must have a low density. The problem which arises is that the plate 1 is then too flexible and does not maintain itself correctly. Two solutions can be envisaged. A first solution would be to increase the thickness of the plate 1, which would decrease the useful volume of the container 4, which is a capital element to be optimized in the field of transport. The second solution would be to increase the density of the plate 1 so that it maintains itself, but the insulation would be reduced and there would be a risk of thermal shock. In order to achieve the same insulation with sufficient density to hold the plate 1, the thickness of this plate 1 must be increased and therefore the useful volume of the container 4 must be reduced.

To keep adequate insulation with the smallest possible wall thickness, those skilled in the art would also be led to think of using a low density cork sheet but reinforced with another rigid material. The latter would not think of compressing the cork wall in order to provide it with more rigid external surfaces 2 to keep the internal part 3 insulating.

The insulated container 4 of the figure 2 seen from above, uses internal diffusing plates 1 in compressed cork. Concretely, the insulated container 4 includes walls around a volume 5 capable of receiving the content to keep at a certain temperature. The container 4 is characterized in that each wall comprises an external cork plate 6, a space 7 which can contain, and here containing, at least one thermal source 8 and an internal plate 1 produced by compression of cork. Said internal plate 1 separates the heat source 8 from the content located in the volume 5. In addition, said internal plate 1 has the density of its external surfaces 2 higher than that of its internal part 3 in order to diffuse the temperature as desired. The geometry of the internal plate 1 will affect the speed of transmission of the temperature from the thermal sources 8 to the volume 5 capable of receiving the content which must be maintained at a certain temperature. Indeed, depending on the thickness of the sublayers 2 and 3 in the internal plate 1 and the densities of these sublayers 2 and 3, the temperature spreads more or less quickly. This makes it possible to manage the broadcasting time, depending for example on the transport time of the content to be kept under controlled temperature.

In addition, the external plate 6 has a lower density than the internal plate 1 in order to force the heat flow to go towards the volume 5, and not towards the outside of the container 4.

As a thermal source, we can consider ice cubes, containers of a hot liquid, ...

In some cases, the insulated container 4, the walls of which form an isothermal primary space 5, can be placed in an external packaging with secondary space 11 for securing and protecting the isothermal primary space 5. In fact, the container is in some cases placed in a package, which allows it to have a cover 10 and a bottom 9. This packaging, which can be made of cardboard for example, is practical for transport. Packaging is a means of solidarity and protection. But in most cases, the container itself already includes a bottom and a lid. The packaging then only adds an additional cover 10 and bottom 9 to the container 4.

Space 7 can contain a thermal source, but in some cases it can be dispensed with. In fact, the container of the invention can be used simply by using the fact that the external walls, during transport or storage, allow the external temperature to gradually pass, the external walls regulating the passage of this temperature.

According to a preferred embodiment of the invention, the insulated container 4 has the shape of a rectangular parallelepiped.

Claims (7)

1. Method for producing a diffusing sheet of cork for an isothermic container, characterised in that, a starting sheet of cork with an initial density is compressed so as to laterally increase the density, and to form hardened outer skins (2) with a higher level of diffusion compared to the initial level, and thereby control the diffusion of the compressed sheet.
2. Method for producing a diffusing sheet of cork (1) for an isothermic container according to claim 1, said starting sheet of cork being compressed over the whole of the surface thereof.
3. Diffusing sheet of cork (1) for an isothermic container, characterised in that it is produced according to the production method of claim 1.
4. Isothermic container (4) comprising walls, said walls comprising an outer sheet of cork (6) and an inner sheet of cork (1), with an interstitial space (7) arranged to receive a heat source (8), the walls being arranged to receive a content (5), characterised in that said inner sheet (1) is a sheet according to claim 3.
5. Isothermic container (4) according to claim 4, said inner sheet (1) having a higher density than said outer wall (6).
6. Isothermic container (4) according to one of claims 4 and 5 wherein said walls form a primary isothermic space 5 closed by a bottom and a cover of a packaging with a secondary space for receiving said walls.
7. Isothermic container (4) according to any one of claims 4 to 6 which has the shape of a parallelepiped rectangle.

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