Claims
- 1. In a process for imparting antistatic properties on a substrate which only conducts electrical current poorly or not at all wherein a coating of an electroconductive organic polymer is applied onto the surface of the substrate, the improvement which comprises producing on the surface of the substrate a coating of a polythiophene which consists of structural units of the formula ##STR7## in which A is an C.sub.1 -C.sub.4 -alkylene radical or a substituted C.sub.1 -C.sub.4 -alkylene radical,
- by oxydative polymerization of a 3,4-disubstituted thiophene of the formula ##STR8## in which A has the meaning indicated under formula (I).
- 2. The process of claim 1, wherein A is a methylene radical, alkyl-substituted methylene radical, an 1,2-ethylene radical, an 1,2-ethylene radical wich is substituted by C.sub.1 -C.sub.12 -alkyl or phenyl or a 1,2-cyclohexylene radical.
- 3. The process of claim 1 wherein the oxidant is an alkali metal persulphate, an ammonium persulphate or an iron(III) salt of an organic acid or of inorganic acid containing an organic radical, and this oxidant is applied together with the 3,4-disubstituted thiophene of the formula (II) from one solution or printing paste onto the substrate to be provided with the antistatic properties.
Priority Claims (2)
| Number |
Date |
Country |
Kind |
| 3813589 |
Apr 1988 |
DEX |
|
| 3843412 |
Dec 1988 |
DEX |
|
(a) EP-A-0,206,133:
This is a division of application Ser. No. 337,498, filed Apr. 13, 1989, now U.S. Pat. Ser. No. 4,959,430, patented Sept. 25, 1990.
The invention relates to new polythiophenes of high electrical conductivity, their preparation by oxidative polymerization of the corresponding thiophenes, and the use of the polythiophenes for imparting antistatic properties on substrates which only conduct electrical current poorly or not at all, in particular on plastic mouldings, and as electrode material for rechargeable batteries.
2. Description of Related Art
Polythiophenes, their preparation by electrochemical or chemical oxidation of the corresponding thiophenes, and the use of the polythiophenes for imparting antistatic properties on substrates which only conduct electrical current poorly or not at all are known; see, for example:
This discloses a process for applying coatings of conductive, polymeric heterocyclic compounds produced with the aid of oxidants onto substrates which conduct electrical current only poorly or not at all. However, only the imparting of antistatic properties on substrates by means of polypyrrole produced on the substrates by oxidative polymerization of pyrrole is described;
This publication describes specific thiophenes substituted in the 3- and/or 4-position by (substituted) alkyl and/or alkoxy groups and the electroconductive polymers obtained from them by chemical or electrochemical oxidation. According to the data given in the publication, the polythiophenes obtained by chemical oxidation only have poor conductivity;
This publication describes the preparation of polymeric 3-alkylthiophenes by reacting 3-alkyl-2,5-dihalogeno-thiophenes with magnesium in the presence of nickel compounds in inert organic solvents. The electroconductivity of the undoped polythiophenes obtained in this way is given as being 9.times.10.sup.-14 S/cm;
Both publications concern the preparation of substituted conductive polythiophenes which are soluble in organic solvents, and the use of the solutions of these soluble polythiophenes for imparting antistatic properties on substrates which only conduct electrical current poorly or not at all. The preparation of the soluble, substituted, conductive polythiophenes or solutions thereof is carried out by electrochemical oxidation of the corresponding substituted thiophenes (EP-A 257,573) or by reacting the corresponding 2,5-dihalogenothiophenes with magnesium in the presence of nickel catalysts (EP-A 203,438); the last-mentioned process is virtually impossible to carry out on an industrial scale, and the polythiophenes obtained by electrochemical oxidation only have very low conductivity.
Surprisingly, it has been found that a specific type of 3,4-disubstituted polythiophenes is particularly suitable for imparting antistatic properties on substrates which only conduct electrical current poorly or not at all, since it has a high electroconductivity and since, in addition, it can be prepared directly on the substrates to be provided with antistatic properties by chemical oxidation of the parent 3,4-disubstituted thiophenes using customary oxidants. This is because it has been found that the polymerization rates of the specific thiophenes can be varied through the choice of oxidant and, in particular, can be adjusted so that it is no longer necessary to apply the oxidant and substituted thiophenes separately to the substrate to be provided with antistatic properties, as has hitherto been necessary in the case of provision of antistatic properties using polypyrrole, but instead so that it is possible to apply the substituted thiophenes and oxidants to the substrates to be treated in combined form together in a solution of printing paste.
US Referenced Citations (2)
| Number |
Name |
Date |
Kind |
| 4898921 |
Humphrey et al. |
Feb 1990 |
|
| 4900782 |
Han et al. |
Feb 1990 |
|
Divisions (1)
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Number |
Date |
Country |
| Parent |
337498 |
Apr 1989 |
|
Patent Grant
5035926
