Electrode and method for applying an electrical potential to a surface of a conductive or non-conductive material

Abstract

Electrode for applying an electrical potential to a surface of a conductive or non-conductive material. The electrode comprises a first electrically conductive material extending at least partially parallel to the surface, in particular a metal wire, and a second electrically conductive material extending at least partially parallel to the surface. Furthermore, an electrical contact is provided which connects the first electrically conductive material to the second electrically conductive material, wherein the first electrically conductive material has a greater conductivity than the second electrically conductive material. Furthermore, the second electrically conductive material comprises at least one organic substance.

Description

[0001] 1 / 14 9590 - JK

[0002] Windmöller & Hölscher SE & Co. KG

[0003] Münsterstraße 50

[0004] 49525 Lengerich / Westphalia

[0005] Our reference number: 9590 JK

[0006] Electrode and a method for applying an electrical potential to the surface of a conductive or non-conductive material

[0007] The invention relates to an electrode and a method for applying an electrical potential to the surface of a conductive or non-conductive material.

[0008] Various materials, especially plastic materials and preferably plastic films, are frequently subjected to an electrical potential in order to influence their properties.

[0009] For this process, the material is subjected to an electrical potential via an electrode. This electrode typically does not touch the material. The material is placed on or passed over an object that is subjected to a further electrical potential. This object is often grounded, so that the additional electrical potential is zero. In the case of plastic films, this object is frequently a roller or cylinder over which the plastic film runs.

[0010] To produce noticeable effects in materials, especially plastic films, it is necessary to generate high potential differences between the electrode and the object. Needle electrodes are frequently used, in which a number of needles are arranged in a row, with the row extending parallel to the surface of the material. The needles themselves are usually oriented orthogonally to the surface of the material. Thus, a very strong electric field can emanate from each needle tip. 2 / 14 9590 - JK

[0011] The problem here, however, is that an inhomogeneous electric field is also present at the surface of the material, meaning the material is not affected uniformly. This electric field can cause a charge displacement, resulting in an electrical charge at least at the surface of the material. With an inhomogeneous electric field, the charge displacements within the material vary locally. Permanent traces can remain in the material, which can be detrimental to subsequent processing steps.

[0012] To homogenize the electric field and thus avoid permanent marks in the material, patent W02023001837, "Electrode and method for applying pressure to a surface of a conductive or non-conductive material," proposes a device which replaces the majority of needles with a continuous band consisting of two electrically conductive materials, the first of which has a higher conductivity than the second. The aforementioned patent application is a reference to the present patent application, both in terms of content and definitions, and is therefore to be considered an integral part of the present patent application.

[0013] Since the lower conductivity of the second material is intended to prevent the formation of sudden discharges that lead to lightning, finding a suitable material is a balancing act between an electrically insulating and an electrically conductive material. The goal is to find a material whose conductivity for the application lies within a suitable range between very high and very low conductivity. However, finding materials with a suitable conductivity has proven difficult. Furthermore, most materials are sensitive to overheating. When isolated lightning strikes occur, the high temperatures in the vicinity damage the surfaces of many materials, thus shortening the electrode's service life. This also applies to "heat-resistant" materials such as glass or ceramics, which are also very expensive and difficult to process.

[0014] The object of the present invention is therefore to propose an electrode and a method in which the second material has a suitable conductivity.

[0015] According to the invention, this problem is solved by all the features of claim 1. Possible embodiments of the invention are specified in the dependent claims.

[0016] According to the invention, the second electrically conductive material comprises at least a portion of an organic substance.

[0017] For the purposes of the invention, an electrically conductive material is a material that can comprise various chemical substances. This material can be a component, for example a metal wire, wherein the metal used can comprise an alloy. However, the material can also comprise a component with a layered structure of various electrically conductive substances.

[0018] Organic substances within the meaning of the invention comprise chemical compounds containing carbon and / or carbon-carbon and / or carbon-hydrogen bonds. These compounds often contain hydrocarbon chains in which the carbon atoms are linked together by single bonds, such as polyethylene (C2H4). n , Polypropylene (CsHe) but also polystyrene (C8H8) n Because of the small difference in electronegativity between hydrogen (2.2 eV) and carbon (2.5 eV), charge shifts within the molecules are negligible. They are therefore considered nonpolar. Consequently, these chemical compounds, also known as saturated hydrocarbons, are typically excellent electrical insulators.

[0019] The invention is based on the understanding that the electrical conductivity of various hydrocarbons differs widely, particularly when other atoms and / or molecules, which at least partially do not comprise carbon and / or hydrogen, are present in these hydrocarbons. For this reason, not all hydrocarbons are electrical insulators.

[0020] If the second electrically conductive material of the electrode at least partially comprises an organic substance, a desirable high electrical resistance or low conductivity results, so that uncontrolled discharges and thus the formation of lightning are avoided.

[0021] The conductivity of organic substances can depend on the properties of the individual molecule, but also on the interaction of several molecules with each other. For example, it is known that certain hydrocarbons form a crystal structure (especially when inorganic compounds are also involved) that leads to semiconducting properties. Thus, there are chemical variations of organic compounds that are capable of conducting electric current to the desired extent, so that one or more of these organic substances can be used, at least partially, to conduct the electric current in the electrode. In an advantageous embodiment of the invention, it is therefore provided that the at least one organic substance has semiconducting properties, i.e., is an electrical semiconductor. The electrical resistance of such materials is preferably in the range between 100 kΩ and 300 MΩ.

[0022] It is advantageous if the second electrically conductive material comprises an organic substance with carbon compounds, wherein semiconducting properties are generated by periodic interruptions of the carbon bonds, in particular by atoms of chemical elements from a different chemical group than carbon or hydrogen. By suitable doping with foreign atoms that can provide charge carriers, polymers can be produced whose conductivity is greater than that of the same polymers without doping. The degree of doping determines the conductivity of the polymer and, in particular, its semiconducting properties. Furthermore, it is possible that carbon bonds are interrupted by atoms of other chemical elements, such as oxygen, which can also impart semiconductor properties to the organic molecules.For example, in polyethylene glycol, the carbon compound, which forms a carbon chain, has an oxygen atom incorporated at every second carbon atom further along. OH groups are located at the ends of each carbon chain. Such a carbon compound also possesses semiconductor properties.

[0023] Furthermore, it can be advantageous if the second electrically conductive material comprises an organic compound with carbon compounds, where the carbon compounds are at least partially conjugated carbon compounds. For example, unsaturated hydrocarbons are known in which double bonds occur between two carbon atoms due to the absence of hydrogen atoms. In these conjugated carbon compounds, such as polyacetylene, single bonds alternate with double bonds between the carbon atoms. The extended electron system can confer electrically conductive properties, particularly semiconductor properties, to such organic molecules.

[0024] Depending on the length of the carbon chain or the size of the molar mass, this organic substance exists as either a solid or a liquid. It is advantageous if the organic substance exists in the solid state under normal conditions. In this case, the organic substance is easy to handle and, above all, can be formed into a desired shape.

[0025] In this context, "solid" means any organic substance or mixture of organic substances that has at least a partially solid state of matter under normal conditions (10 to 40 degrees Celsius, ambient pressure 900 to 1100 mbar), in particular under standard conditions (20 degrees Celsius, ambient pressure 950 mbar), or that assumes at least a partially solid state of matter under the application conditions (temperatures up to 180 degrees Celsius) of a 6 / 14 9590 - JK generic electrode.

[0026] However, it can also be advantageous if the organic substance is in a liquid state under normal conditions. In this context, "liquid" refers to any organic substance or organic mixture that exhibits at least a partially flowable state under normal conditions or assumes at least a partially flowable state under the operating conditions of a generic electrode.

[0027] The operating conditions of a generic electrode are understood to be the conditions that a generic electrode itself generates, such as the presence of a high voltage, the existence of an electric field, and / or the local increase in the temperature of the air and / or at least parts of the electrode due to the presence of a plasma.

[0028] A plasma is a mixture of particles consisting of ions, free electrons, and usually also neutral atoms or molecules. A plasma contains free charge carriers. The ionization degree of a plasma can be less than 1%, but also 100%. The formation of a plasma is a reaction of the air to the potential difference generated by the electrode. Charges are transported from the electrode to the material by the air. Since air has electrical resistance, it heats up when it conducts an electric current.

[0029] However, this also refers to the conditions that the electrode encounters at its place of application, such as the conditions that exist in different parts of a production line for plastic films, such as an air temperature of 100 °C and more.

[0030] A further advantage of the invention is that the second electrically conductive material is at least partially represented by an organic liquid, wherein the liquid at least partially wets the other chemical components of the second electrically conductive material. This results in a further advantage, as the organic liquid acts like a liquid surface of the second material. In the case of isolated, uncontrolled discharges and lightning strikes, damage to the surface of the second material is replaced and thus repaired by the flowing organic liquid. This results in a self-healing surface that significantly increases the service life of the electrode.

[0031] Further advantages, features, and details of the invention will become apparent from the following description, in which various exemplary embodiments are explained in detail with reference to the figures. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination thereof. Within the scope of the entire disclosure, features and details described in connection with the method according to the invention naturally also apply in connection with the device according to the invention, and vice versa, so that the disclosure always makes, or can make, reciprocal references to the individual aspects of the invention.

[0032] The individual figures show:

[0033] Fig. 1 A schematic section through a simple strip electrode,

[0034] Fig. 2 A schematic section through a strip electrode with porous

[0035] Complete material and supply of organic fluid,

[0036] Fig. 3 A schematic section through a strip electrode with replaceable porous solid material and

[0037] Fig. 4 A schematic front view of a strip electrode according to Figure 3 and

[0038] Fig. 5 An electrode assembly with two electrodes designed as strip electrodes according to Fig. 4. 8 / 14 9590 - JK

[0039] In the various figures of the drawing, identical parts are always labelled with the same reference symbols.

[0040] For the following description, it is claimed that the invention is not limited to the exemplary embodiments and not to all or several features of the described combinations of features, but that each individual partial feature of the exemplary embodiment(s) is also significant for the subject matter of the invention independently of all other partial features described in connection therewith and also in combination with any features of another exemplary embodiment.

[0041] Fig. 1 shows a cross-section of an electrode according to the invention, which comprises a solid component 4 as a shaper. The shaper can be, for example, a plate or a frame. This component 4 preferably comprises an electrically insulating material, such as polyethylene, wood, or glass. This component 4 is enclosed by a porous material 2. The porous material 2 can be, for example, a sponge, nonwoven fabric, or a woven fabric stretched around the component 4 and held together by an electrical contact 3 in the form of a seam made of a wire, in particular a copper wire. Here, "wire" is not understood to mean only an element with a round cross-section; rather, the wire can have any cross-sectional shape. A wire can therefore also be formed as a metal strip. Alternatively, the seam can also comprise any type of thread, including a non-conductive one.In this case, however, a separate wire is provided, which is pressed against the porous material 2, for example by means of the thread, so that an electrical contact is created between the wire and the porous material 2.

[0042] To activate the electrode, it is briefly immersed in a liquid 11 containing an organic substance. The porous material 2 absorbs and at least temporarily stores the liquid, so that the porous material is saturated with the liquid 11. The excess liquid 11 can be wiped off or will drip off on its own. The electrode is then ready for use.

[0043] In this context, the electrical contact 3 is considered the first electrically conductive material with high conductivity, while the combination of component 4 and the porous material 2, which is at least partially saturated with liquid 11, is considered the second electrically conductive material within the meaning of the invention. A high voltage can be applied to the electrical contact 3. The tip of the electrode 10 points towards the material (not shown) that is to be influenced by the electrical potential.

[0044] The liquid 11 conducts the electric current towards the electrode tip 10. Here, the electrostatic field lines become more concentrated due to the shape of the electrode tip 10, and the air is ionized. For this to occur, the material preferably has an electrical potential of zero, as already described in the introductory section.

[0045] While component 4 and porous material 2 are electrically insulating, liquid 11 conducts electricity with an electrical resistance, thus preventing uncontrolled local discharges. Therefore, liquid 11 can be considered an electrically conductive fluid.

[0046] The advantages of this embodiment are its particularly simple design and ease of implementation.

[0047] Fig. 2 shows a cross-section through another embodiment of the electrode according to the invention.

[0048] A solid 1, impregnated with a liquid 11 comprising an organic substance, forms, together with a cutting edge 9 and a sharpened cutting edge 10, the second electrically conductive material with low conductivity. The solid itself is preferably an insulator. The solid 1 can, for example, comprise pores, in particular micropores, in which the liquid can be absorbed and / or with which the liquid can interact within the 10 / 14 9590 - JK

[0049] The solid 1 can be conductive. However, the solid 1 can also be fibrous and, for example, comprise paper. In general, the solid 1 is designed to absorb, store, and release liquids. The second electrically conductive material thus formed is arranged between two liquid-tight housing plates 5, which form a housing, and is equipped with an electrical contact 3, for example, in the form of a seam made of a wire, in particular a copper wire. Alternatively, the electrical contact 3, which can also at least partially comprise a metal strip, can be kept in contact with the solid 6 by the housing plates 5.

[0050] Electrical contact 3, in turn, represents the first electrically conductive material with high conductivity.

[0051] The solid 1 can be supplied with liquid 11 via a hose 8, thus compensating for any liquid loss within the electrode. The electrode housing has an inlet or connection for the hose 8, which supplies the liquid 11. A fluid-contact connection exists between the hose connection and the solid 1, allowing the liquid 11 to reach the solid 1.

[0052] The cutting edge 9 has a very small radius at its cutting edge 10, resulting in a high concentration of electrostatic field lines. This makes the electrode effective at ionizing air. The straightness of the sharpened cutting edge 9 leads to a clearly defined electrostatic field. The continuous supply of liquid 11 prevents the electrode from drying out.

[0053] Fig. 3 shows a cross-section through another embodiment of the electrode according to the invention, in which the solid 1 can be easily replaced. As in the embodiment according to Fig. 2, the housing consists of two housing plates 5 between which the solid 1, exposed to the liquid 11, is held. It has a cutting edge 9 11 / 14 9590 - JK with a particularly sharpened cutting edge 10. The solid 1 can have a smaller overall extent in the direction of the tube 8 than the solid according to the embodiment of Fig. 2. In this case, a cavity remains in the housing, which is filled with the liquid 11. To prevent the solid 1 from moving relative to the housing, it is preferably secured in the housing by means of at least one seal 7 by means of a force-fit and / or form-fit connection.A further seal 6 between the housing plates 5 projects into the cavity containing the liquid 11 and is equipped with an electrical contact 3, which can again be configured as already described in connection with Figures 1 and 2. The electrical contact 3 is also surrounded or saturated by the liquid 11, so that the electrical voltage from the electrical contact 3 penetrates through the liquid 11 to the cutting edge 10 of the solid 1 and ionizes the air there. By separating the housing plates 5, the solid 1 is exposed and can be easily replaced. The electrical contact 3 can remain in the housing and is preferably not replaced.

[0054] In this context, the electrical contact 3, preferably in the form of a seam made of wire, particularly copper wire, can be considered the first electrically conductive material, while the combination of the solid 1 and the liquid 11, which is enclosed in a cavity, represents the second material. The electrical connection between the first and second materials is created by the liquid 1 flowing around the electrical contact 3.

[0055] Figure 4 shows a front view of the electrode, which has already been described in connection with Figure 3. Visible is the front plate of the housing 5, which is firmly but detachably connected to the rear housing plate (not visible) by means of screws. The seal 6, also not visible, is located between these plates. The other elements correspond to those of Figure 3, so they do not need to be discussed again here. It is worth noting that the hose 8 is centrally located on the housing 5. In this case, a single hose is sufficient. However, multiple hoses can also be used.

[0056] Hoses should be provided if the liquid 11 is to be distributed evenly across the width of the electrode. This is recommended if the housing 5 does not have a cavity but is, for example, completely filled with a solid, as shown in Figure 2. The entire electrode, and in particular the cutting edge 10, extends parallel to the material. This applies to all embodiments of the present invention. Since a liquid 11 is used in the electrode, it is recommended that the cutting edge be arranged horizontally to the ground and that the housing 5 extend at least partially in the direction of gravity so that the liquid 11 can flow towards the cutting edge 10. Additionally or alternatively, the same effect can be achieved by pressurizing the liquid 11.

[0057] Fig. 5 shows a particular embodiment of the invention, which relates to an electrode assembly with two or more electrodes of the aforementioned type. In particular, due to field weakening and voltage drop when the electrode is widened or lengthened parallel to a longitudinal extension of the electrode, especially the cutting edge 10, which runs parallel to the surface of the material, the voltage must be increased to achieve the same effect. Furthermore, widening or lengthening the electrode can lead to uncontrolled discharges or electrical flashovers. An extension of the electrode can also lead to mechanical instability. A particular embodiment therefore consists in arranging two or more electrodes of the aforementioned type side by side such that the cutting edges 10 of the at least two electrodes are aligned with each other.This allows for the advantageous provision of an electrode group width 12, or the effectively treatable material width to be increased, without having to increase the peak voltage. Advantageously, each electrode may be provided with its own voltage supply via its own electrical contact 3, wherein the two respective electrical contacts 3 are preferably connected independently of each other. A particular advantage of several electrodes arranged in alignment can also be that the 13 / 14 9590 - JK.

[0058] The material can be treated with different potentials across the entire material width achievable by the electrode assembly, as the electrodes can be subjected to different voltages. This can offer various advantages depending on the process.

[0059] In the figures, the reference symbol "PEG" denotes polyethylene glycol, which is an example of liquid 11. PEG can be supplied to the electrode via tube 8.

[0060] The invention is not limited to the illustrated and described embodiments, but also encompasses all embodiments that have the same effect within the meaning of the invention. The embodiments are not limited to the combination of all features; rather, each individual partial feature can have inventive relevance independently of all other partial features. Furthermore, the invention is not limited to the combination of features defined in the independent claims, but can also be defined by any other combination of specific features of all disclosed individual features. Consequently, each individual feature of the respective independent claims can be omitted and / or replaced by at least one individual feature disclosed elsewhere in the application.

[0061] 14 / 14 9590 - JK

[0062] Reference symbol list

[0063] 1 solid 2 porous material

[0064] 3 electrical contacts

[0065] 4 components

[0066] 5 Housing plate

[0067] 6 Seal 7 Seal

[0068] 8 hose

[0069] 9 cutting edge

[0070] 10 Cutting edge

[0071] 11 Liquid 12 Treatable material width

[0072] PEG Polyethylene glycol

Claims

1 / 4 9590 - JK Windmöller & Hölscher SE & Co. KG Münsterstraße 50 49525 Lengerich / Westphalia Our reference number: 9590 JK Electrode and a method for applying an electrical potential to the surface of a conductive or non-conductive material Claims 1. Electrode for applying an electrical potential, particularly one that causes electrical polarization, to a surface of a conductive or non-conductive material, in particular a plastic material, comprising a first electrically conductive material extending at least partially parallel to the surface, in particular a metal wire, a second electrically conductive material extending at least partially parallel to the surface, and at least one electrical contact connecting the first electrically conductive material to the second electrically conductive material, wherein the first electrically conductive material has a higher conductivity than the second electrically conductive material, characterized in that the second electrically conductive material comprises at least one organic substance.

2. Electrode according to claim 1, characterized in that the organic material is an electrical semiconductor.

3. Electrode according to one of the preceding claims, characterized in that 2 / 4 9590 - JK the second electrically conductive material comprises an organic substance with carbon compounds, wherein semiconducting properties are produced by an, in particular periodic, interruption of the carbon compounds, in particular by atoms of chemical elements of a chemical main group other than carbon or hydrogen.

4. Electrode according to one of the preceding claims, characterized in that the second electrically conductive material comprises an organic substance with carbon compounds, wherein the carbon compounds are at least partially conjugated carbon compounds.

5. Electrode according to one of the preceding claims, characterized in that the organic substance is in the solid state under normal conditions.

6. Electrode according to one of the preceding claims, characterized in that the organic substance is in the liquid state under normal conditions, and preferably comprises polyethylene glycol.

7. Electrode according to one of the preceding claims, characterized in that the second material comprises an electrically non-conductive solid with which at least parts of the organic substance can be absorbed and / or stored and / or released.

8. Electrode according to one of the preceding claims, characterized in that the second material is at least partially represented by the organic liquid under normal conditions, wherein the organic liquid 3 / 4 9590 - JK is enclosed in a cavity, with the first electrically conductive material being surrounded by the organic liquid.

9. Electrode according to one of the preceding claims, characterized in that an access point and a supply line, in particular a hose, is provided through which the organic liquid can be supplied to the solid.

10. Electrode assembly comprising at least two electrodes according to one of claims 1 to 9, wherein the electrodes are arranged parallel to the surface of the material and aligned with each other in a longitudinal extent of the electrode.

11. Method for applying an electrical potential causing electrical polarization to the surface of a conductive or non-conductive material, in particular a plastic material, wherein a first electrically conductive material, in particular a metal wire, extending at least partially parallel to the surface, is applied an electrical potential, wherein the material is at least partially exposed to the potential via a second electrically conductive material, extending at least partially parallel to the surface, wherein the second electrically conductive material is brought at least partially to the electrical potential by means of at least one electrical connecting wire connecting the first electrically conductive material to the second electrically conductive material, wherein the first electrical material has a higher conductivity than the second electrically conductive material.wherein the second electrically conductive material at least partially comprises an organic substance that conducts the current.

12. Method according to claim 10, characterized in that 4 / 4 9590 - JK by means of an electrode assembly according to claim 9 the material can be subjected to different potentials over a material width treatable by means of the electrode assembly, in that the electrodes of the electrode assembly can be subjected to different voltages relative to each other.

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