WO2004048227A1

WO2004048227A1 - Electrically conductive container

Info

Publication number: WO2004048227A1
Application number: PCT/EP2003/013308
Authority: WO
Inventors: Tony Dhoop
Original assignee: Rosenlew Fibc Benelux N. V.
Priority date: 2002-11-26
Filing date: 2003-11-25
Publication date: 2004-06-10
Also published as: AU2003293728A1; FI20022098A; FI20022098A0

Abstract

The present invention relates to an electrically conductive container comprising an outer package (11) and an inner package (12) inserted in the outer package (11). Both the outer and the inner packages (11, 12) are made of electrically conductive materials and connected to one another so that the connection forms an electrically conductive link (14) from the inner package (12) to the outer package (11). The inner package (12) is made of a multi-layer material, where at least the layers (12a, 12b) that may come in contact with the contents of the container, i.e. the inner and outer layers (12a, 12b) of the multi-layer material are made of a food and pharmaceuticals approved polymer. A separate electrically conductive core layer (12c) is sandwiched between said inner and outer layers (12a, 12b), so that said core layer (12c) is prevented to come into contact with the contents of the container.

Description

ELECTRICALLY CONDUCTIVE CONTAINER

Background of the Invention

1. Field of the Invention

The present invention relates to an electrically conductive container, and more particularly to an electrically conductive container such as a sack or bag for filling, transporting and storing powdered, granular or bulk material. Still more particularly the present invention relates to a package for food, pharmaceuticals, fine chemicals and/or similar materials requiring high hygiene of the package. The package may be e.g. FIBC (Flexible Intermediate Bulk Container, big bag, collapsible container) or RIBC (Rigid Intermediate Bulk Container).

2. Description of the Prior Art

Certain products create a dust when filled into a container. This dust can be electrically charged due to static electricity and can have high voltages and create sparks and therefore the contents of the container produce a dust explosion risk. Attempts have been made to overcome this problem and for this purpose it has been proposed to make the container from an electrically conductive material so that such static electricity can be led away to the ground whereby the risk of sparks is minimized. Such container may also be used and discharged in circumstances, where sparks could be dangerous, e.g. in connection of flammable prod- ucts. Electrically conductive containers of different types are known in the art. These containers are typically made of a fabric or similar material having electrically conductive yarns woven, knitted, or otherwise incorporated therein. Alternatively these containers may also have different combinations of carbon layers or carbon fibers to lead away the charges. However, food and pharmaceuticals typically may not be in direct contact with carbon. Foods and pharmaceuticals further often require an inner packaging made of special polymers to protect the contents from contamination. These polymers are typically non-conductive (e.g. PE, PP), and additives improving conductivity make the product not approved for food contact.

With respect to the prior art, reference is made to U.S. Patents Nos. 6,207,592, 6,331 ,334 and 4,948,265, U.S. Patent Application Publication No. 2001/0014567, European Patent Application Publications Nos. 1197445 and 0456328, British Paten Application No. 2101559 and German Utility Model No. 8909967.2 U1. These publications show either different containers or container bags made of electrically conductive material or they show conductive fabrics or materials for containers. European Patent Application No. 0456328 represents the closest prior art. Therein is disclosed a container bag which comprises a body of flexible material (an outer package) and a woven inner lining (an inner package), whereby both the body and the lining are made of electrically conductive material and they are connected to one another electrically. The conductivity of the body and liner has been obtained by conductive threads woven into the fabric. The electrical connection between the body and the liner is obtained by stitching or sewing with a conductive thread. A significant disadvantage of this prior art container is the fact that it cannot be used in connection with food, pharmaceuticals or similar materials. At first this due to the structure of the liner, and secondly to the manner by which the bag body and the liner are connected to one another. The material to be packaged can become into contact with the conductive threads woven into the liner and it can also become into contact with the conductive threads with which the bag body and the liner are electrically connected to one another. The materials used in this bag are not approved for food contact. Summary of the Invention

The present invention aims to obtain an improvement upon the aforementioned conventional electrically conductive containers and to solve the problems confront- ing those containers, especially as to containers intended for food and pharmaceuticals.

Therefore, the object of the present invention is to provide an electrically conductive container for filling, transporting and storing powdered, granular or bulk mate- rial, especially for food, pharmaceuticals, fine chemicals and/or similar materials requiring high hygiene of the package.

The above-described object of the present invention is attained by an electrically conductive container comprising an outer package and an inner package inserted in the outer package, whereby both the outer and the inner package are made of electrically conductive materials and connected to one another so that the connection forms an electrically conductive link from the inner package to the outer package.

The improvement of the container is characterized in that the inner package is made of a multi-layer material, where at least the layers that may come in contact with the contents of the container, i.e. the inner and outer layers of the multi-layer material are made of a food and pharmaceuticals approved polymer and a separate electrically conductive layer is sandwiched between said inner and outer lay- ers, so that it is prevented to come into contact with the contents of the container.

The advantage of the invention is the fact that during filling of the container and when the container full the contents of the container may come into contact with a food and pharmaceuticals approved polymer only and not at all with the electrically conductive material layer, whereby the container is extremely hygienic and it can be used for materials to be packaged requiring high level of hygiene. Brief Description of the Drawings

FIG. 1 is a schematic and partially cross-sectional view showing an example of the container according to the present invention.

FIG. 2 shows the detail II of FIG. 1 in a larger scale.

Detailed Description of the Invention

By way of illustration FIG. 1 shows the inventive container generally denoted with reference number 10. In FIG. 1 the container 10 is a collapsible container, e.g. a big bag or a flexible intermediate bulk container (FIBC), but it is to be understood that the invention is applicable also for other types of containers. As an example, the invention is applicable rigid intermediate bulk containers (RIBC). The container 10 or package consist of an outer package 11 and an inner package 12 inserted into said outer package 11. The container is also provided with lifting loops 18 fastened, preferably stitched to the outer package 11.

In the embodiment shown in FIG. 1 the container 10 is further provided with an inlet opening 15 defined by the fill spout 17 of the inner package 12. Said fill spout 17 is surrounded by a collar 16 formed of the outer package 11. At the bottom 10' of the container a discharge spout 19 is provided. Further, in the embodiment shown the container 10 may be composed of several parts of which the wall parts are denoted with reference numeral 10a. The wall parts 10a and the bottom 10' are attached to one another by seams 14, 14a, 14', preferably by stitched seams. FIG. 1 shows further that in this embodiment of the invention at least at one of the seams 14 the inner package 12 is provided with wings 13 which are sewn in said seam 14 of the outer package 11. This is shown and explained in a more detailed manner in connection with FIG. 2. As mentioned before FIG. 2 shows the detail II of FIG. 1 in a larger scale. According to the invention the container 10 comprises an outer package 1 and an inner package 12 inserted in the outer package 11. The outer package 1 1 is made of electrically conductive material, e.g. fabric that may be uncoated. There are sev- eral possible ways to make the fabric electrically conductive and according to one possible embodiment conductive threads or yarns are woven into the fabric. The inner package 12 is also made of an electrically conductive material and according to the present invention it is made of a multi-layer material consisting of at least three layers 12a, 12b, 12c. Because the inventive container 10 is particularly in- tended to be used in connection with food, pharmaceuticals, fine chemicals, etc, at least the layers that may come in contact with the contents, i.e. the inner layer 12a and the outer layer 12b of the inner package 12 are made of food and pharmaceuticals approved polymer. Typically this polymer may be polyolefine plastic, e.g. LDPE. In order to make the multi-layered material of the inner package 12 electri- cally conductive a separate conductive layer, i.e. a core layer 12c is sandwiched between the inner and outer layers 12a, 12b of said inner package 12. The conductive core layer 12c may be e.g. a carbon layer, a layer of electrically conductive polymer, etc. Depending on the polymers used there may be some tie layers in the structure of the inner package 12. There may be adhesive layers between the in- ner, outer and core layers 12a, 12b, 12c of the material of the inner package 12 by which adhesives said layers are bonded to one another.

The inner package 12 is fixed to the outer package 11 so that there is an electrically conductive link 14 from the inner package to the outer package. This can be made e.g. by stitching, stapling, etc. In the embodiment shown in FIGS. 1 and 2 the inner and outer packages 1 1 , 12 are stitched or sewn together with a conductive yarn or thread 14 from the wings 13 formed therein so that said yarn or thread 14 forms a conductive link from the inner package 12 (from the conductive core layer 2c of the inner package) to the conductive outer package 1. However it is not necessary that the inner and outer packages 11 , 12 should be sewn together along the whole length of a seam of the container 10, but there should be a conductive link between said packages 11 , 12 at least at one point.

The conductive link 14 between the inner and outer packages 11 , 12 may be made in several ways. The inventive container 10 is intended to be used in connection with food, pharmaceuticals, fine chemicals, etc, and so the container 10 as a whole must be approved for those purposes. This means that the container 10 must be formed so that the contents of the container will not come in contact with the fixing of the conductive link 14 between said packages. In the embodiment shown in FIG. 2 the inner package 12 is heat-sealed at the inner side of the conductive link 14 so that a seal 20 is formed that prevents the contents of the container to come in contact with the conductive link.

Even though the inner and outer surfaces of the inner package 12, i.e. the inner and outer layers 12a, 12b of said inner package are of non-conductive material, said layers being very thin allow an electrical charge to dissipate to the conductive core layer 12c. Through the conductive link 14 between the inner and outer packages 11 , 12 the charge is eventually grounded. A container of this type is now certified to be conductive and approved for food contact.

Claims

1. Electrically conductive container comprising an outer package (11) and an inner package (12) inserted in the outer package (11), whereby both the outer and the inner packages (11, 12) are made of electrically conductive materials and connected to one another so that the connection forms an electrically conductive link (14) from the inner package ( 2) to the outer package (11), characterized in that the inner package (12) is made of a multi-layer material, where at least the layers (12a, 12b) that may come in contact with the contents of the container (10), i.e. the inner and outer layers (12a, 12b) of the multi-layer material are made of a food and pharmaceuticals approved polymer and a separate electrically conductive core layer (12c) is sandwiched between said inner and outer layers (12a, 12b), so that said core layer (12c) is prevented to come into contact with the contents of the container (10).

2. Electrically conductive container according to claim 1, characterized in that the multi-layer material of the inner package (12) comprises at least one tie layer.

3. Electrically conductive container according to claim 1 or2, c h a ra c te r ized in that the multi-layer material of the inner package (12) comprises ad- hesives between the layers to bond said layers to one another.

4. Electrically conductive container according to anyone of the previous claims, c haracterized in that the electrically conductive core layer is a carbon layer.

5. Electrically conductive container according to anyone of the previous claims, c h aracte rized in that the electrically conductive core layer is made of electrically conductive polymer.