EP2185749B1 - Device and method for producing electrically conductive nanostructures by means of electrospinning - Google Patents

Description

The invention is based on known methods for producing structures of electrically conductive material using printing methods. The invention relates to a method with which it is possible to deposit nanofibers targeted with high local precision on any surface. This is made possible by a particularly adapted process of so-called electrospinning in conjunction with a material suitable for this, from which the electrically conductive structures are formed by the structures consist of conductive particles or subjected to a post-treatment to generate conductivity.

Many components (e.g., many automotive interiors; panes) and everyday necessities (e.g., beverage bottles) are essentially made of electrically insulating materials. This includes both known polymers, such as polyvinyl chloride, polypropylene, etc., but also ceramics, glass and other mineral materials. In many cases, the insulating effect of the component is desired (for example in the case of mobile computer housings). However, there is also a frequent need to provide such components or articles with an electrically conductive surface or structure to, for example, integrate electronic functions directly into the device or article.

Other requirements for the surface of everyday objects and their material are the greatest possible creative freedom in the design, positive mechanical properties (eg high impact resistance), as well as certain optical properties (eg transparency, gloss, etc.), in particular of the above exemplified materials be achieved with different weighting.

There is therefore a need to maintain the positive properties of the material and to selectively produce a conductive surface. In particular, the optical transparency and gloss are technically demanding in this context. They can only be reached via three routes. Either the substrate material itself is deliberately made conductive without impairing its mechanical and optical properties, or a material is used which is conductive, but visually optically imperceptible to humans and can be easily applied selectively to the surface of the substrate, or a conductive material is used which, although not transparent itself, can be applied to the surface by means of a suitable process such that the resulting structure is suitable for human beings Generally without the aid of optical aids is imperceptible. This does not affect the gloss and transparency properties of the substrate.

In general, any structure that is not visually perceptible, which, applied to a two-dimensional surface in one of its two dimensions on the substrate plane, does not exceed a characteristic length of 20 μm. In order to surely suppress any influence on the surface perception, submicron-scale structures (i.e., having a line width of ≤ μm) are particularly desirable.

There are a large number of methods for applying particularly conductive material to surfaces. In particular, common printing methods, such as screen printing or inkjet printing are suitable for this purpose. Particularly for these printing techniques, corresponding formulations for conductive materials already exist - also called inks - which, in conjunction with the methods, make conductive structures on the surface representable.

While screen printing methods are principally incapable of producing structures in an optical resolution of less than 1 .mu.m because of the smallest available mesh size of the printing screens, ink jet printing methods would theoretically be able to do so since the dimensions of the resulting structure on the substrate in the case of inkjet printing processes can be directly correlated with the Nozzle diameter of the printhead used correlate. However, as a rule, the characteristic length of the minimum dimension of the resulting structure is greater than the diameter of the nozzle head used. [ J. Mater. Sci. 2006, 41, 4153 ; Adv. Mater. 2006, 18, 2101 Nevertheless, structures with a line width of less than 1 μm could in principle be produced if printers with nozzle openings significantly below 1 μm could be used. However, this is impractical in practice, since with increasing reduction of the nozzle diameter, the requirements for the usable inks rise sharply. If the ink used contains particles, then their average diameter would have to follow the reduction of the nozzle diameter, which in principle precludes all inks with particles ≥1 μm. Furthermore, the requirement for the rheological properties of the ink (eg, viscosity, surface tension, etc.) increases to be usable by the printhead. In many cases, however, these parameters are not adjustable separately from the behavior (eg spreading and adhesion) of the ink on the respective substrate, which renders the combination of ink-printing methods unusable for the production of conductive structures in this size range.

A method by which structures smaller than 1 μm can alternatively be represented on polymer surfaces is the so-called hot embossing. By the method have already been Circular surface structures with a diameter of approx. 25 nm are shown [ Appl. Phys. Lett. 1995, 67, 3114 ; Adv. Mater. 2000, 12, 189 ]. Disadvantage of hot stamping, however, is the restriction of the structural shape to the shape of the embossing stamp or embossing roll used in each case. A free design of the structure is not possible hereby.

Particularly thin fibers, which could also potentially be applied to the surface of a suitable substrate, can be produced by means of a method which has established itself under the name "electrospinning". This makes it possible to produce fibers of a few nanometers diameter using a spinnable material [ Angew. Chem. 2007, 119, 5770-5805 ].

Electrospun fibers are only obtained in the form of large, disordered fiber mats. Ordered fibers are so far only possible by spinning on a rotating roll [ Biomacromolecules, 2002, 3, 232 ]. It is also known that in principle conductive fibers can be spun by means of "electrospinning". A corresponding conductive material for such use utilizing the conductivity of carbon nanotubes is also known. [ Langmuir, 2004, 20 (22), 9852 ].

In US2001-0045547 discloses methods and materials that can be used to obtain conductive fiber mats.

Targeted deposition of non-conductive fibers on flat surfaces could be achieved by reducing the distance between the spinner and the substrate. [ Nano Letters, 2006, 6, 839 ].

So far, no electrically conductive structures with a targeted arrangement on a substrate surface prepared by means of electrospinning have been described.

In US2005-0287366 discloses a method and material that can be used to produce conductive fibers. The method involves electrospinning at a distance of about 200 mm, so that also disordered fiber mats are obtained. The material is a polymer which is rendered conductive via further post-treatment steps involving a thermal treatment. A specific orientation and application of the fibers obtained on a substrate is not disclosed.

It is therefore an object of the invention to develop a process with which targeted, conductive structures can be generated on a surface visually for the human eye using electrospinning technology.

The object is achieved by the use of a device for producing conductive linear structures having a line width of at most 5 .mu.m on a particular non-electrically conductive substrate, which is the subject of the invention, at least comprising a substrate holder, a spinning capillary, with a supply of a spinning liquid and an electrical power supply is connected, a controllable movement unit for moving the spinning capillary and / or the substrate holder relative to each other, an optical measuring device, in particular a camera, for tracking the spinning process at the output of the spinning capillary, and a computing unit for controlling the distance of the spinning capillary relative to Substrate support depending on the spinning process.

The spinning capillary preferably has an opening width of not more than 1 mm.

Particularly preferred is a device in which the spinning capillary has a circular opening with an inner diameter of 0.01 to 1 mm, preferably 0.01 to 0.5 mm, particularly preferably 0.01 to 0.1 mm.

In a preferred embodiment of the new device, the voltage supply delivers an output voltage of up to 10 kV, preferably from 0.1 to 10 kV, particularly preferably from 1 to 10 kV, very particularly preferably from 2 to 6 kV.

In a further preferred embodiment, the controllable movement unit serves to move the substrate holder.

Also preferred is a device, characterized in that the spinning capillary is adjustable to a distance of 0.1 to 10 mm, preferably 1 to 5 mm, more preferably 2 to 4 mm to the substrate surface.

In a particularly preferred variant of the device, the stock for the spinning liquid is provided with a conveying device which conveys the spinning liquid into the spinning capillary. For example, this is a piston syringe, which is provided with a motor spindle as a piston propulsion.

The invention also provides a process for producing conductive linear structures having a line width of at most 5 μm on a, in particular non-electrically conductive substrate by electrospinning, characterized in that a spinning liquid based on an electrically conductive material or a precursor compound for an electrically conductive material from a spinning capillary having an opening width of not more than 1 mm while applying an electrical voltage between substrate or substrate holder and spinning capillary or spinning capillary holder of at least 100 V at a distance of at most 10 mm between the output of the spinning capillary and the surface of the substrate is spun onto the substrate surface and the substrate surface is moved relative to the output of the spinning capillary, wherein the relative movement is controlled depending on the spin flow that removes the solvent of the spinning liquid and optionally the precursor erverbindung is treated to an electrically conductive material.

Suitable substrates are electrically non-conductive or poorly conductive materials such as plastics, glass or ceramic, or semiconducting materials such as silicon, germanium, gallium arsenide and zinc sulfide. In a preferred method, the distance between the exit of the spinning capillary and the substrate surface is set to 0.1 to 10 mm, preferably 1 to 5 mm, particularly preferably 2 to 4 mm.

The viscosity of the spinning liquid is preferably at most 15 Pa.s, more preferably 0.5 to 15 Pa.s, more preferably 1 to 10 Pa.s, most preferably 1 to 5 Pa.s.

The spinning liquid preferably comprises at least one solvent, in particular at least one selected from the group: water, C ₁ -C ₆ -alcohol, acetone, dimethylformamide, dimethylacetamide, dimethylsulfoxide and meta-cresol, a polymeric additive, preferably polyethylene oxide, polyacrylonitrile, polyvinylpyrrolidone, Carboxymethylcellulose or polyamide and a conductive material.

Particularly preferred is a method in which the spin liquid contains as conductive material at least one of the series: conductive polymer, a metal powder, a metal oxide powder, carbon nanotubes, graphite and carbon black.

The conductive polymer is particularly preferably selected from the series: polypyrrole, polyaniline, polythiophene, polyphenylenevinylene, polyparaphenylene, polyethylene dioxythiophene, polyfluorene, polyacetylene, particularly preferably polyethylenedioxythiophene / polystyrenesulphonic acid.

In the event that the spinning liquid as a conductive material preferably at least one metal powder of the metals silver, gold and copper, preferably silver is used as the solvent, a dispersant-containing water and optionally additionally C ₁ - C ₆ alcohol, wherein the metal powder is present in dispersed form and has a particle diameter of at most 150 nm.

Preferably, the dispersing aid comprises at least one agent selected from the group: alkoxylates, alkylolamides, esters, amine oxides, alkylpolyglucosides, alkylphenols, arylalkylphenols, water-soluble homopolymers, water-soluble random copolymers, water-soluble block copolymers, water-soluble graft polymers, in particular polyvinyl alcohols, copolymers of polyvinyl alcohols and polyvinyl acetates, polyvinylpyrrolidones, Cellulose, starch, gelatin, gelatin derivatives, amino acid polymers, polylysine, polyaspartic acid, polyacrylates, polyethylene sulfonates, polystyrenesulfonates, polymethacrylates, condensation products of aromatic sulfonic acids with formaldehyde, naphthalenesulfonates, lignosulfonates, copolymers of acrylic monomers, polyethylenimines, polyvinylamines, polyallylamines, poly (2-vinylpyridines), Block copolyether, block copolyether with polystyrene blocks and / or polydiallyldimethylammonium chloride.

A particularly preferred spinning liquid is characterized in that the silver particles a) have an effective particle diameter of 10 to 150 nm, preferably from 40 to 80 nm, determined by laser correlation spectroscopy.

The silver particles are preferably contained in the formulation in a proportion of 1 to 35 wt .-%, particularly preferably 15 to 25 wt .-%.

The content of dispersing agent in the spinning liquid is preferably 0.02 to 5 wt .-%, particularly preferably 0.04 to 2 wt .-%.

The size determination by means of laser correlation spectroscopy is known from the literature and z. B. described in T. Allen, Particle Size Measurements, Vol. 1, Kluver Academic Publishers, 1999 ,

In another variant of the new method, a spinning liquid is used which has a precursor compound for an electrically conductive material which is selected from the series: polyacrylonitrile, polypyrrole, polyaniline, polyethylenedioxythiophene and additionally a metal salt, in particular an iron (III) salt preferably contains iron (III) nitrate. When Solvents come here z. For example, acetone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, meta-cresol and water in question.

The method is very particularly preferably carried out in such a way that the above-described new apparatus or one of its preferred variants is used for spinning the spinning liquid.

By means of the device, the desired fine conductive structures are produced by electrospinning. Depending on the spinning solution used, it will be necessary to post-treat the structures to achieve or increase the desired conductivity.

When the voltage is applied between the capillary or capillary holder and the substrate holder, a drop forms at the opening of the capillary, from which the filament emerges.

Furthermore, receptacle for capillary and substrate are designed so that a relative positioning of capillary opening to the substrate surface is possible. In a particular embodiment, the capillary can be positioned above the substrate by means of positioning motors, in another it is possible with positioning motors to position the substrate under the capillary during spinning. In particular, substrate and capillary can be moved. Preferably, the substrate is moved under the capillary.

In order to produce the desired conductive structures from the spinning liquid, it should be ensured that the spinning process is stabilized such that the resulting structure on the surface has no breaks. This is preferably achieved by regulating the capillary distance relative to the substrate surface by interrupting the continuation of the line via a control loop as a function of a camera image, if obviously the filament breaks off. More preferably, the stabilization of the process is achieved so that a computer analyzes the image of the camera and interrupts the relative advancement of the capillary with respect to the substrate if the analysis results in a break, a change in linewidth, or a bubble in the continuous fiber.

The camera can be positioned anywhere, eg. B. in transparent substrates below the substrate or near the capillary opening.

The minimum voltage to be applied in the process varies linearly with the set distance and is also dependent on the type of spinning fluid. Preferably, an operating voltage of 0.1 to 10 kV should be used for spinning for structured laying of the fibers, as described above.

Particularly good results were obtained when the distance between the head of the capillary and substrate surface was 0.1 to 10 mm.

It has furthermore been found that the material to be spun for carrying out the process should have a viscosity of in particular not more than 15 Pa · s in order to reliably produce conductive structures with the spinning material.

After the steps described above, the specified material is desirably on the substrate and may be post-treated as needed to increase conductivity.

For example, This post-treatment includes the entry of energy into the generated structures. In the case of conductive polymers (especially polyethylenedioxythiophene), the polymer particles present in suspension in the solvent are e.g. fused together by heating the suspension on the substrate while the solvent evaporates at least partially. Preferably, the post-treatment step is carried out at least at the melting temperature of the conductive polymer, more preferably above its melting temperature. This creates continuous tracks. Also preferred is a post-treatment of the structures / fibers on the substrate by means of microwave radiation.

In the case of a spun carbon nanotube-containing material, the aftertreatment of the generated lines vaporizes the solvent between the dispersed particulates to obtain continuous, carbon nanotube, percolatable webs. The treatment step is in this case carried out in the region of the evaporation temperature of the solvent contained in the material or above, preferably above the evaporation temperature of the solvent. Once the percolation limit has been reached, the desired printed conductors are created.

Alternatively, conductive structures can also be produced by depositing a precursor material for an electrically conductive material, for example polyacrylonitrile (PAN), on the substrate and is annealed under changing gaseous media to produce carbon as a conductive substance, as described below.

In this case, a solution of a polymer (e.g., PAN or carboxymethyl cellulose) and a metal salt (e.g., a ferric salt such as ferric nitrate) is prepared in a solvent suitable for both components (e.g., DMF). The polymer should be convertible to a conductive material stable at such temperatures. Particularly preferred polymers are those which can be converted to carbon by high temperature treatment. Particularly preferred are graphitizable polymers (e.g., polyacrylonitrile at 700-1000 ° C). Among the metal salts, those whose decomposition temperature or decomposition temperature under the reductive atmosphere is below the decomposition temperature of the respective polymer (e.g., ferric nitrate nonahydrate at 150 ° C to 350 ° C) are preferred. After the conversion of the metal salts into metal particles, preferably by purely thermal decomposition or gaseous reducing agents, particularly preferably by hydrogen, the polymer is converted into carbon in the presence of the metal particles. Finally, if appropriate, carbon is additionally deposited on the structures from the gas phase, preferably by chemical vapor deposition from hydrocarbons. For this purpose, volatile carbon precursors are passed over the structures at high temperatures. Preference is given here to using short-chain aliphatics, more preferably e.g. Methane, ethane, propane, butane, pentane, or hexane, particularly preferably the liquid at room temperature aliphatic n-pentane and n-hexane. In this case, the temperatures should be selected so that the metal particles promote the growth of tubular carbon filaments and an additional graphite layer along the fiber. For iron particles, this temperature range is e.g. between 700 and 1000 ° C, preferably between 800-850 ° C. The duration of the vapor deposition in the above case is between 5 minutes and 60 minutes, preferably between 10 to 30 minutes.

If, in accordance with a preferred procedure, the above-described suspensions of noble metal nanoparticles in solvents are used as spinning liquid for producing conductive structures, the aftertreatment can be carried out by heating the entire component or specifically the printed conductors to a temperature at which the metal particles sinter together and the solvent at least partially evaporated. In this case, the smallest possible particle diameters are advantageous, since with nanoscale particles the sintering temperature is proportional to the particle size, so that a lower sintering temperature is required for smaller particles. Here, the boiling point of the solvent is as close as possible to the sintering temperature of the particles and is as low as possible to protect the substrate thermally. The solvent of the spinning liquid preferably boils at a temperature <250 ° C, especially preferably at a temperature <200 ° C, particularly preferably at a temperature ≤ 100 ° C. All temperatures given here are based on boiling temperatures at a pressure of 1013 hPa. The sintering step is carried out at the indicated temperatures until a continuous conductor has been formed. This is preferably a period of one minute to 24 hours, more preferably from five minutes to 8 hours, particularly preferably from two to eight hours.

The new method is used in particular for the production of substrates which have conductive structures on their surface which have a dimension of not more than 1 μm in one dimension, preferably from 1 μm to 50 nm, particularly preferably from 500 nm to 50 nm, wherein the conductive material is preferably a suspension of conductive particles as described above, and the substrate is preferably transparent, for example to glass, ceramic, semiconductor material or a transparent polymer as described above.

The invention will be described below using the FIG. 1 exemplified in more detail. FIG. 1 shows a schematic of the spinning device according to the invention.

Examples example 1 (Conductive nanostructures with carbon nanotubes):

• Die Halterung 1 für das Substrat 9, eine Siliziumscheibe und die metallische Fassung 13 der Spinnkapillare 2, welche mit einem Flüssigkeitsvorrat 3 für die Spinnlösung 4 versehen ist. sind mit einer elektrischen Spannungsversorgung 5 verbunden. Die Spannungsversorgung 5 stellt elektrische Gleichspannung bis zu 10 kV zur Verfügung. Die Spinnkapillare 2 ist eine Glaskapillare mit einem Innendurchmesser von 100 µm. Der regelbare Stellmotor 6 dient zur Bewegung der Spinnkapillare 2 und der Stellmotor 6' zur Bewegung der Substrathalterung 1 relativ zueinander um den Abstand zwischen diesen einzustellen. Die Kamera 7 ist zur Verfolgung des Spinnvorgangs auf den Ausgang der Spinnkapillare 2 ausgerichtet, und mit einem Rechner 8 mit Bildverarbeitungssoftware zur Auswertung der Bilddaten der Kamera verbunden. Der Vortrieb des Motors 6' der Substrathalterung 1 wird vom Rechner 8 geregelt in Abhängigkeit vom Austritt der Spinnlösung 4 aus der Spinnkapillare 2.

For spinning the spinning solution, the following apparatus (see Fig. 1 ) used:

• The holder 1 for the substrate 9, a silicon wafer and the metallic frame 13 of the spinning capillary 2, which is provided with a liquid supply 3 for the spinning solution 4. are connected to an electrical power supply 5. The power supply 5 provides electrical DC voltage up to 10 kV available. The spinning capillary 2 is a glass capillary with an internal diameter of 100 μm. The controllable servo motor 6 is used to move the spinning capillary 2 and the servomotor 6 'to move the substrate holder 1 relative to each other to adjust the distance between them. The camera 7 is aligned to follow the spinning process to the output of the spinning capillary 2, and connected to a computer 8 with image processing software for evaluating the image data of the camera. The propulsion of the motor 6 'of the substrate holder 1 is controlled by the computer 8 in dependence on the exit of the spinning solution 4 from the spinning capillary 2.

A spinning solution 4 of 10% by weight of polyacrylonitrile (PAN: average molecular weight 210,000 g / mol) and 5% by weight of iron (III) nitrate nonahydrate in dimethylformamide was prepared. The viscosity of the resulting solution was about 4.1 Pa · s. The spinning process was initiated at a distance of 0.6 mm between the capillary opening and the surface of the substrate 9 at a voltage of 1.9 kV between spinning capillary 2 and substrate 9. After setting a stable fiber flow, the voltage was adjusted to 0.47 kV and the distance increased to 2.2 mm. In this setting, the spinning solution 4 was spun onto the surface of the substrate 9 and the substrate moved laterally to produce lines.

The substrate 9 with the obtained PAN fibers was subsequently within 90 min. heated from 20 to 200 ° C, then treated for 60 minutes at 200 ° C. Thereafter, the air of the drying oven in which the sample 9 was located, was replaced by argon and the temperature increased to 250 ° C within 30 minutes. Argon was then replaced by hydrogen. Under this hydrogen atmosphere, the temperature was again kept at 250 ° C for 60 minutes. The mixture was then switched back to argon as gas for the drying oven and the sample 9 was heated to a temperature of 800 ° C within two hours. Finally, the argon was added to the argon hexane for seven minutes and finally the sample 9 was cooled back to room temperature under argon. The cooling process was not regulated, but it was waited until the interior of the furnace had reached a temperature of 20 ° C.

The result was a conductive line based essentially on carbon. When contacting two points of the line at a distance of 190 microns, a resistance of 1.3 kOhm was measured. The line had a linewidth of about 130 nm.

Claims (16)

1. Apparatus for producing conductive linear structures having a line width of at most 5 µm on a specifically non-electrically conducting substrate (9), comprising at least a substrate holder (1), a spinning capillary (2), which is connected to a reservoir (3) for a spinning liquid (4) and to an electrical voltage supply (5), an adjustable movement unit (6, 6') for moving the spinning capillary (2) and/or the substrate holder (1) relative to each other, an optical measuring device (7), specifically a camera, for tracking the spinning process at the point of exit from the spinning capillary (2) and an arithmetic processing unit (8) for controlling the distance of the spinning capillary (2) from the substrate holder (1) according to the spinning process.
2. Apparatus according to Claim 1, characterized in that the spinning capillary (2) has an opening width of not more than 1 mm.
3. Apparatus according to Claim 2, characterized in that the spinning capillary (2) has a circularly round opening with an internal diameter of 0.01 to 1 mm, preferably 0.25 to 0.75 mm, more preferably 0.5 to 0.3 mm.
4. Apparatus according to any of Claims 1 to 3, characterized in that the voltage supply (5) delivers an output voltage of up to 10 kV, preferably of 0.1 to 10 kV, more preferably 1 kV to 10 kV, most preferably 2 to 6 kV.
5. Apparatus according to any of Claims 1 to 3, characterized in that the adjustable movement unit (6') serves to move the substrate holder (1).
6. Apparatus according to any of Claims 1 to 3, characterized in that the spinning capillary (2) is adjustable to a distance of 0.1 to 10 mm, preferably 1 to 5 mm, more preferably 2 to 4 mm from the substrate surface.
7. Apparatus according to any of Claims 1 to 3, characterized in that the reservoir (3) comprises a conveying device (12) which conveys the spinning liquid (4) into the spinning capillary (2).
8. Method for producing conductive linear structures having a line width of at most 5 µm on a specifically non-electrically conducting substrate (9) by electrospinning, characterized in that a spinning liquid (4) based on an electrically conducting material or a precursor compound for an electrically conducting material is spun onto the substrate surface (10) from a spinning capillary (2) having an opening width of no more than 1 mm by applying an electrical voltage of at least 100 V between the substrate (9) or substrate holder (1) and the spinning capillary (2) or spinning capillary holder (13) at a distance of at most 10 mm between the point of exit (11) of the spinning capillary (2) and the surface of the substrate (9) and the substrate surface (10) is moved relative to the point of exit (11) of the spinning capillary (2), wherein the relative movement is controlled according to the spin flux, removing the solvent of the spinning liquid (4) and post-treating any precursor compound to form an electrically conducting material.
9. Method according to Claim 8, characterized in that the distance between the point of exit (11) of the spinning capillary (2) and the substrate surface (10) is adjusted to 0.1 to 10 mm, preferably 1 to 5 mm, more preferably 2 to 4 mm.
10. Method according to Claim 8 or 9, characterized in that the viscosity of the spinning liquid (4) is at most 15 Pa•s, preferably 0.5 to 15 Pa•s, more preferably 1 to 10 Pa•s, most preferably 1 to 5 Pa•s.
11. Method according to any of Claims 8 to 10, characterized in that the spinning liquid (4) consists at least of a solvent, specifically selected from the series: water, C1-C6 alcohol, acetone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide and meta-cresol, a polymeric additive, preferably polyethylene oxide, polyacrylonitrile, polyvinylpyrrolidone, carboxymethylcellulose or polyamide, and a conductive material.
12. Method according to Claim 11, characterized in that the spinning liquid (4) contains as conductive material at least one from the series: conductive polymer, a metal powder, a metal oxide powder, carbon nanotubes, graphite and carbon black.
13. Method according to Claim 12, characterized in that the conductive polymer is selected from the series: polypyrrole, polyaniline, polythiophene, polyphenylenevinylene, polyparaphenylene, polyethylenedioxythiophene, polyfluorene, polyacetylene, preferably polyethylenedioxythiophene/polystyrene sulfonic acid.
14. Method according to any of Claims 11 to 13, characterized in that the spinning liquid (4) includes as conductive material at least one metal powder of the metals silver, gold and copper, preferably silver and, as solvent, water containing a dispersant and optionally C1-C6 alcohol, wherein the metal powder is present in disperse form and has a particle diameter of at most 150 nm.
15. Method according to any of Claims 8 to 10, characterized in that the spinning liquid (4) includes a precursor compound for an electrically conducting material, said precursor compound being selected from the series: polyacrylonitrile, polypyrrole, polyaniline, polyethylenedioxythiophene and additional metal salt specifically iron (III) salt.
16. Method according to any of Claims 8 to 15, characterized in that the spinning liquid (4) is spun using apparatus according to any of Claims 1 to 7.

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