EP1245503B1 - Shipping container made of plastic and method for producing a shipping container - Google Patents

Abstract

A transport container (1) made of plastic, contains electrically conducting polymers. A transport container (1) made of plastic, contains electrically conducting polymers. The plastic container is a hollow member and has a volume in excess of 450 liters. The plastic is polyethylene, and the package has a seam. The electrically conducting polymers are applied as a lacquer onto the plastic package, and consist of doped polymers chosen from the polyaniline group. The plastic container is located in a metal cage (9). The container surface is subjected to flame treatment or a corona treatment.

Description

The invention relates to a transport packaging made of plastic according to the preamble of claim 1 and a method for producing a transport packaging according to claim 8. Transport packaging made of plastic are known in various versions and have proven themselves. One problem area is the packaging of ignitable materials and their storage in potentially explosive areas. Plastic packaging can pose a hazard due to the electrostatic charging of its surfaces. Therefore, in the "Static Electricity" guideline ZH1 / 200 of BG Chemistry, Section 7.1.1.4, it is stipulated, for example, that in an Ex zone 1 for substances in explosion group II a, chargeable areas of 100 cm ^{2 are} not exceeded. Electrostatic conductive parts including conductive, i.e. non-rechargeable liquids must therefore be earthed.

If flammable liquids above their lower explosion point are to be handled in plastic transport packaging, it must be assumed that the requirements for avoiding ignition sources in zone 0 must be met on the packaging of the container. For substances in explosion group II a, unshielded chargeable areas must not exceed 25 cm ² .

In order to meet these requirements, closed metallic Outer container suggested that the plastic container completely sheath and thus allow adequate grounding. this has However, the disadvantage that the degree of filling of the container is no longer of is visible from the outside.

Furthermore, a stretchable sack with conductive material has been proposed that can be placed around the plastic container. However, such outer packaging is expensive and complex to use. In addition, it is difficult to ensure that, with such stretchable outer packaging, surely chargeable areas of, for example, 100 cm ^{2 are} not exceeded.

Plastic packaging arranged in a metal cage has also been proposed. The fields of this metal cage are, for example, less than 100 cm ² and the filling cap was made conductive using the copper / zinc sintering process. However, such cages essentially share the disadvantages of the stretchable bag described above.

DE-A-10 013 000 describes glass molded containers and molded parts Plastic. Here are electrically conductive tracks on the inner wall of the Containers or molded parts proposed. The conductive plastic layer should during the ejection process of the plastic melt from the extruder into the Blow mold in a modified coextrusion process directly on the Inner wall of the actual container are applied.

US-A-5,759,649 proposes a three-layer plastic container composite plastic cover. The outer layer consists of a Polymer, the inner layer consists of a perforated polymer and the middle layer made of an electrically conductive material. The middle layer is used for grounding according to the invention. Preferably here thin aluminum foils are used. In a special Embodiment suggests that the conductive layer part should be the outer container layer, the conductive layer should be inside the container. Ultimately, it was suggested the plastic container with soot particles to be electrically conductive. Adequate soot addition leads however, to the fact that the plastic container is no longer translucent and the level is no longer easily recognizable from the outside is. The pigments introduced also reduce the shelf life the container and lead to tearing, particularly in the case of drop tests the container at the weld line.

The invention is therefore based on the object of a transport packaging to further develop plastic in such a way that it is better in potentially explosive atmospheres Areas can be used.

This task is solved in that a stable, hollow transport packaging, made of plastic with a volume of over 450 liters of electrical paint applied to the transport packaging Has conductive polymers.

The characterizing features of claim 1 make it possible to manufacture plastic transport packaging, whose surface has a high conductivity. Preferably lies the specific resistance below 106 ohms x meters. This leads to no longer surround the plastic packaging with metal grids or nets plastic packaging for hazardous areas can be manufactured very inexpensively.

The use of electrically conductive polymers in the manufacture of the Packaging also means that if the Tankes the discharge layer is always arranged on the tank. Provided as a result of heating the tank volume increases, this is This is also an advantage when the network is pulled over the tank. Provided However, if the tank contracts, the distance usually increases between the net drawn over the tank and the outer wall of the tank, so that proper derivation is no longer guaranteed. If however, the tank is emptied without opening an air flow the tank comes together relatively quickly and it is created at this very moment the risk of explosion due to electrostatic charges.

The plastic packaging is a stable hollow body. Hollow bodies allow containers to be produced in a simple manner, which are suitable, for example, for the transport of liquids. Such containers are in large quantities for transport and the storage of explosive or flammable substances.

The invention relates to hollow bodies that have a volume of over Have 450 liters. These are usually 1000 liter plastic containers, special equipment due to the use of electrically conductive polymers to avoid electrostatic ignition hazards in potentially explosive atmospheres Areas of Zone 1Group II A preserved.

The polymers are used as a varnish on the plastic packaging applied. This enables two in the seam area to combine pure polymer materials with each other without this Polymers occur that affect the strength of the seam could. The paint is advantageously only after the creation of the Interface applied to the finished hollow plastic container.

Such a lacquer layer can be on the inside as well as on the outside be applied to the plastic packaging, especially at It is proposed that the polymers on the outside of the Plastic packaging is applied. This causes the cargo is derived on the outside of the packaging and makes it easier to to provide an electrically conductive layer with an earthing.

Such transport packaging made of polyethylene is advantageous manufactured. HDPE should be mentioned here in particular.

In a simple manufacturing variant, these plastic packaging blown from an extruded piece of tubing, the Hose is pressed together at the separation points. This creates Seams that are particularly at risk in terms of strength. The invention relates above all to plastic packaging that has a seam have, since the electrically conductive polymers to the strength only slightly affected the seams.

The polymers do not necessarily have to be continuous Lacquer layer can be applied, but can also be used as a net Layer be applied. The use of a mesh-like layer is reduced the amount of necessary polymers and ensures transparency of the container.

A preferred embodiment provides that the polymers as translucent layer are applied. Such a layer allows Recognizability of the degree of filling of the container, even if the container is completely covered with a layer of lacquer.

Positive results have been achieved with doped polymers that are made from the group of conjugated chain molecules, such as. B. the polyanilines come.

The object of the invention is also achieved with a method of manufacture a transport packaging solved, in which a surface of a Plastic packaging for flame treatment or corona treatment undergoes and the plastic packaging with an electric paint containing conductive polymers is sprayed.

The flame treatment or the corona treatment ensures that the as a layer, a good hold on the plastic surface finds and apply a uniformly thin layer of lacquer can. For this purpose, spraying is particularly suggested, as it does such industrial packaging quickly and in industrial use can be treated equally.

It is advantageous if the sprayed transport packaging in a metal cage is arranged. The metal cage can be done easily be grounded and it ensures that an electrically conductive connection between the lacquer layer comprising electrically conductive polymers and grounding is achieved. The metal cage also forms one mechanical protection for transport packaging.

An embodiment of a transport packaging according to the invention is shown in the figure and is explained in more detail below. It shows the only figure is a three-dimensional view of a pallet container.

The pallet container 1 shown in FIG. 1 is a so-called intermediate Bulk Container (IBC), for example as a 1000 liter plastic container for the transport of liquid and ignitable materials serves. However, the invention is not limited to such pallet containers but also affects plastic drums, plastic canisters such as polyethylene and polypropylene and open packaging, especially for explosive substances.

The pallet container 1 consists essentially of a plastic bladder 2 and a pallet 3. The plastic bladder 2 is made in the present case HDPE made and the pallet made of wood. However, are suitable as a pallet also particularly good metallic pallets, as these are the grounding of the container facilitate.

The plastic bladder 2 of the transport packaging 1 has on its upper side 4 a lid 5. This lid 5 is made of electrically conductive material produced or has electrically conductive polymers. Here is the Form conductive surface of the plastic cover 5 so that it with the surface of the plastic bladder 2 comes into contact thereby to be grounded. At the bottom 6 of the plastic bladder 2 is an outlet 7 provided that the filling and in particular an emptying of the Allows container.

The plastic bladder 2 of the transport packaging 1 has on its outside a lacquer layer 8, which contains electrically conductive polymers. The lacquer layer is translucent and slightly greenish and therefore allows it to recognize the level in the container from the outside. To the plastic bubble A metal cage 9 is arranged around it, which consists of vertical struts 10 and horizontal struts 11 and 12 is formed. This metal cage 9 holds the plastic bladder 2 firmly on the pallet 3 and is grounded (not shown) accidental.

With a static charge of the plastic bladder 2, the charge of Surface of the plastic bubble through the electrically conductive polymers the applied layer of paint is passed on until it with the metal cage 9 comes into contact. The charge is on the metal cage 9 subsequently derived because the metal cage 9 is provided with an earth is. The cover 5 and the outlet tap 7 are either electrically conductive connected or standing with the outer surface of the plastic bladder 2 directly connected to the metal cage 9 in order to also in these areas to avoid electrical charging.

The applied varnish with electrically conductive polymers enables a specific resistance of less than 10 ³ Ohm X meters and thus ensures safe dissipation of electrostatic charges. The applied lacquer also has the advantage that it increases UV protection, which has a particularly advantageous effect on the contents.

By varying the proportion of conjugated chain molecules in the application varnish, specific surface resistances of 10 ³ to 10 ⁶ ohm X meters can be set.

Claims (9)

1. A stable, hollow transport package (1) made of plastic with a volume in excess of 450 litres comprising a layer of electrically conductive polymers, characterized in that said layer is coated as a varnish (8) onto the transport package (1).
2. The transport package according to one of the afore-mentioned claims, characterized in that it is manufactured from polyethylene.
3. The transport package according to one of the afore-mentioned claims, characterized in that it comprises a seam.
4. The transport package according to one of the afore-mentioned claims, characterized in that the polymers are coated onto the outer side of the plastic package (2)
5. The transport package according to one of the afore-mentioned claims, characterized in that the polymers are coated as a reticular layer.
6. The transport package according to one of the afore-mentioned claims, characterized in that the polymers are coated as a translucent layer.
7. The transport package according to one of the afore-mentioned claims, characterized in that the polymers used are doped polymers, preferably from the group of the polyanilines.
8. A method of manufacturing a transport package (1) according to claim 1, by which a surface of a plastic package (2) is submitted to a flame treatment or a corona treatment and a varnish (8) containing an electrically conductive polymer is sprayed onto the plastic package.
9. The method according to claim 8, characterized in that the spray coated plastic package (2) is disposed into a metal cage (9).

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