Composites made from conductive polymers and inorganic binders.

p0001The invention relates to composite materials made of electrically conductive materials and inorganic binders.

p0002Conductive polymers containing conjugated double bonds, are known. For example, acetylene or acetylene can be polymerized under the influence of certain Ziegler catalysts. By subsequent doping, this can be done, for example, electrochemically with electron acceptors or electron donors electrically conductive polymers can be obtained (US-PS 4,204,216 and US-PS 4,222,903).

p0003Electrically conductive polymers are obtained by polymerization of 5-membered heterocycles pyrrole or thiophene, for example, on the work AF Diaz et. al. JCS Chem. Comm. 1979, pages 634 ff and page 845 ff and from EP-OS 99 984 known. Another group of electrically conductive polymers, the conductive poly-p-phenylene. These can be obtained for example by the process described in J. Am. Chem. Soc. 1985 (1963) 454 ff and in J. Marcromol. SCI. C 5 (1971) page 295 et seq are described.

p0004Object of the present invention was to show composites made of electrically conductive materials and inorganic binders.

p0005It has now been found that this object is achieved by composite materials that include a p- or n-doped electrically conductive polymer as electrically conductive material containing conjugated double bonds and forms a coherent phase.

p0006Such composites can preferably be found as heating elements, shielding or as probes use.

p0007Among the polymers containing conjugated double bonds, in particular, those polymers which are obtained by electrochemical polymerization of compounds from the class of 5-membered heterocyclic compounds with conjugated π-electron system, the nitrogen or sulfur as a hetero atom are suitable. Advantageously, the polymers from the class of pyrroles and thiophenes. Also suitable are substituted pyrroles, such as n-alkylpyrroles or monoalkyls or dihalo come substituted pyrroles. Compounds from the class of the thiophenes are thiophene next even the 2-, or 3-, or methylthiophene, 2,3-diethylthiophene. The compounds can also be copolymerized together with other copolymerizable compounds or Ocazol diazole. The polymers are prepared by the known processes cited above. The polymerization is therefore advantageously carried out by anodic oxidation in a Elektrolythlösungsmittel containing conductive salts. This gives copolymers wherein the Leitsalzanionen are attached, is called p-doped conductive polymers.

p0008In the same way, the polymers of acetylene can be prepared. The production method is described in the above literature. Advantageously, such Acetylenpolymere in EP 88 301 and in Synthetic Metals<u>5</u> (1982) p 51 are described. Particularly suitable are stretched polymers. In addition, electrically conductive polymers such as poly-p-phenylene are suitable.

p0009The electrically conductive polymers are, for example, with Leitsalzanionen as I⁻, ClO₄⁻, AsF₆⁻ or p-doped with Li⁺, Na⁺, K⁺ or alkaline earth n-doped. The doping can be performed electrochemically or chemically.

p0010For the production of the composite materials, inorganic binders are used. Thus, for example unhydraulische binder such as gypsum, Sorel cement or magnesia use find. Advantageous to use hydraulic binders such Zememt, lime or water glass or other silicates, and borates, vanadates, titanates, Ferate, cuprates or molybdates. Also suitable salts, selenium, sulfur and silicon in question. About binder and cement to give more details in Römpp Chemie Lexikon, 7th edition, page 366 and 3 967th

p0011In the production of composite materials, care should afford, that the electrically conductive polymer forms a coherent phase. That is that the proportions of the polymers with each other are in contact, so that conductivity is possible. Coherent phases form as films, threads or wires, but it may also be used compression moldings from pulverulent polymers. Furthermore, it is possible to use knitted fabric, tissue or disordered poured layers of fibrous polymers. Also suitable are: porous materials such as membranes with open cells or fleece. Thus, it is possible to produce composite materials which have a planar extension and wherein the electrically conductive polymer is included as a core layer. but it is also possible to produce composite materials that consist of only two layers, namely, the polymer and the binder. Furthermore, layered composite materials can often be produced. But you can also make composites that have a longitudinal extent, relates the multiple of the transverse extent. So may be the example belts, cables or ropes, which are surrounded by inorganic means.

p0012The production policy is applied depending on the used inorganic binder. It should be noted here, that in the preparation temperatures are not exceeded, which may lead to a degradation of the polymer. The proportion of the electrically conductive polymers in composite material amounts to 1 part binder 0.001 to 0.1, preferably 0.001 to 0.1 parts.

p0013As already mentioned above, can be found shielding or heating elements use as probes the composites. but they can also be used as electrical controls, or as electrodes.

example 1

p0014A polyacetylene film of 5 microns thickness is prepared according to EP 88 301 is treated for a period of 30 min. With an iodine-containing carbon tetrachloride solution at 23 ° C. The so doped film has a conductivity of 2500 S / cm. The doped film is placed between 2 sheets of potassium, which have a thickness of 3 mm and pressed at 300 bar.

p0015Similarly, the set is to be treated Acetylenfolie between glass plates of 3 mm thickness and pressed at 300 bar and a temperature of 750 ° C.

p0016The composites thus obtained may for example be used as probes.

example 2

p0017A polyacetylene whose doping is described in Example 1, in water glass solution inserted from the solution removed and cured tor at 50 ° C and a pressure of 0.1. It forms a composite of in which a polyacetylene of hardened water glass is embedded. This composite can be used as a control.

example 3

p0018A mixture of 10 parts of sulfur and 5 parts of polypyrrole which has a conductivity of 1 S / cm and is p-doped and in the form of small particles with a diameter of 0.1 mm is compressed at a pressure of 30 bar. It is a compact condition in which the Polypolyrrolteilchen are embedded in the sulfur and form a coherent phase. Such compacts can be found as a probe use.

example 4

p0019There are particles having a diameter of 1 - 2 mm is used, consisting of polypyrrole, is deposited on the graphite particles. The conductivity of these particles is 1 S / cm. The particles with cement and water in the ratio 1: 3 mixed:. 1 The mixture is left for a period of 3 days at 25 ° C cure. The proportion of polypyrrole in the composite is 20 wt .-%. The polypyrrole particles form a coherent phase.

p0020In the same way Polypyrrolfasern are stored, which have a diameter of 1 mm length of 3 to 5 mm and have a conductivity of 2 S / cm. There is obtained a composite material in which the polypropylene fibers forming the coherent phase.

p0021There is inserted a polypyrrole film with a thickness of 200 microns in a cement mixture. The mixture is shaped, so that the film is coated with a layer of 1 cm cement on both sides. It is allowed the cement to harden and receives a composite, wherein the Polypyrrolanteil has a conductivity of 10⁻³ S / cm.

example 5

p0022In an analogous manner as described in Example 4, a Polyproylenfolie is 200 microns in thickness embedded in a plaster, so that the polypropylene film is coated on both sides with a layer of 5 mm. After curing, to obtain a composite. The conductivity of the polypyrrole film in the composite 150 S / cm.

p0023In the same way, a composite element can be made such that a polyacetylene film contains, which is n-doped with lithium anions.