PROCESS FOR PRODUCING FUNCTIONALIZED POLYTHIOPHENES

Abstract

The present invention relates to a process for producing a liquid composition comprising a functionalized ?-conjugated polythiophenes, comprising the process steps of i) providing a liquid phase comprising a) thiophene monomers of the general formula (I) wherein X,Y are identical or different and are O, S, or NR.sup.1, wherein R.sup.1 is hydrogen or an aliphatic or aromatic residue having 1 to 18 carbon atoms; A is organic residue carrying an anionic functional group; b) an oxidizing agent; and c) a solvent; ii) oxidatively polymerizing the thiophene monomers of the general formula (I) to obtain a liquid composition comprising functionalized ?-conjugated polythiophenes; wherein (?1) the pH of the liquid phase provided in process step i) is adjusted to a value below 7.0, wherein the pH is determined at a temperature of 20? C.; and (?2) the chloride content of the liquid phase provided in process step i) is less than 10000 ppm, based on the total weight of the liquid phase. The present invention also relates to the liquid composition obtainable by this process, to a liquid composition comprising a functionalized ?-conjugated polythiophene, wherein the composition is characterized by a certain ratio of mass average molecular weight M.sub.w and the molar average molecular weight M.sub.n of the functionalized ?-conjugated polythiophene, to a liquid composition comprising a functionalized ?-conjugated polythiophene, wherein the functionalized ?-conjugated polythiophene comprises different repeating units in a defined amount, to a process for the preparation of such a liquid composition, to a process for the preparation of a capacitor in which these liquid compositions are used for the formation of the solid electrolyte, to a capacitor obtainable by this process and to the use of the liquid compositions for the preparation of a conductive layer.

Claims

1. A process for producing a liquid composition comprising functionalized ?-conjugated polythiophenes, the process comprising i) providing a liquid phase comprising a) thiophene monomers of formula (I) ##STR00016## wherein X and Y are identical or different and are independently selected from O, S, and NR.sup.1, wherein R.sup.1 is hydrogen or an aliphatic or aromatic residue having 1 to 18 carbon atoms; and A is an organic residue carrying an anionic functional group; b) an oxidizing agent; and c) a solvent; ii) oxidatively polymerizing the thiophene monomers of formula (I) to obtain the liquid composition; wherein (?1) the pH of the liquid phase provided in process step i) is adjusted to a value below 7.0, wherein the pH is determined at a temperature of 20? C.; and (?2) the chloride content of the liquid phase provided in process step i) is less than 10000 ppm, based on the total weight of the liquid phase.

2. The process according to claim 1, wherein (?3) the oxygen content of the liquid phase provided in process step i) is less than 1000 ppm, based on the total weight of the liquid phase.

3. The process according to claim 1, wherein X and Y are O, and A is (CH.sub.2).sub.mCR.sup.2R.sup.3(CH.sub.2).sub.n, wherein R.sup.2 is hydrogen or (CH.sub.2).sub.sZ(CH.sub.2).sub.pSO.sub.3.sup.?M.sup.+, R.sup.3 is (CH.sub.2).sub.sZ(CH.sub.2).sub.pSO.sup.?M.sup.+, Z is O, S or CH.sub.2, M.sup.+ is a cation, m and n are identical or different and are independently an integer from 0 to 3, s is an integer from 0 to 10 and p is an integer from 1 to 18.

4. The process according to claim 1, wherein X and Y are O, and A is (CH.sub.2)CR.sup.2R.sup.3(CH.sub.2).sub.n, wherein R.sup.2 is hydrogen, R.sup.3 is (CH.sub.2).sub.2O(CH.sub.2).sub.pSO.sub.3.sup.?M.sup.+, W is Na.sup.+ or K.sup.+, n is 0 or 1, s is 0 or 1, and p is 4 or 5.

5. The process according to claim 1, wherein X and Y are O, and A is (CH.sub.2CHR), wherein R is (CH.sub.2).sub.tOAr[(W).sub.uSO.sub.3.sup.?M.sup.+].sub.v, wherein Ar is an optionally substituted C.sub.6-C.sub.20 arylene group; W is an optionally substituted C.sub.1-C.sub.6 alkylene group; M.sup.+ represents is H.sup.+, an alkali cation selected from the group consisting of Li.sup.+, Na.sup.+, and K.sup.+, NH(R.sup.1).sub.3 or HNC.sub.5H.sub.5, wherein each R.sup.1 group is independently, a hydrogen atom or an optionally substituted C.sub.1-C.sub.6 alkyl group; t is an integer of 0 to 6; u is an integer of 0 or 1; and v is an integer of 1 to 4.

6. The process according to claim 1, wherein the oxidizing agent b) is a salt of a heavy metal, a salt of a peroxodisulfate, or a mixture thereof.

7. The process according to claim 1, wherein the thiophene monomers are polymerized in process step ii) by electrochemical polymerization and wherein the oxidizing agent b) is an electrode.

8. The process according to claim 1, wherein the solvent c) is water.

9. The process according to claim 1, wherein the pH of the fluid phase provided in process step i) is adjusted to a value below 7.0 using an organic acid or an inorganic acid.

10. The process according to claim 1, wherein the oxidative polymerization in process step ii) is performed under an inert gas atmosphere of nitrogen, argon, carbon dioxide or a mixture thereof.

11. The process according to claim 10, wherein the oxidative polymerization in process step ii) is performed under a pressure that is equal to or above the vapor pressure of the liquid phase during the polymerization reaction in process step ii).

12. The process according to claim 1, wherein the oxidative polymerization in process step ii) is performed under a reduced pressure of not more than 0.8 bar.

13. A liquid composition obtained by the process according to claim 1.

14. A liquid composition comprising a functionalized ?-conjugated polythiophene, wherein the polythiophene comprises repeating units of formula (I) ##STR00017## wherein X and Y are identical or different and are independently selected from O, S, and NR.sup.1, wherein R.sup.1 is hydrogen or an aliphatic or aromatic residue having 1 to 18 carbon atoms; and A is an organic residue carrying an anionic functional group; and wherein the ratio of the mass average molecular weight M.sub.w to the molar average molecular weight M.sub.n (M.sub.w/M.sub.n) of the functionalized ?-conjugated polythiophene is at least 6.

15. The liquid composition according to claim 14, wherein the mass average molecular weight M.sub.w of the functionalized ?-conjugated polythiophene is at least 50000 g/mol.

16. The liquid composition according to claim 15, wherein the mass average molecular weight M.sub.w of the functionalized ?-conjugated polythiophene is in the range from 125000 g/mol to 240000 g/mol.

17. The liquid composition according to claim 14, wherein the molar average molecular weight M.sub.n of the functionalized ?-conjugated polythiophene is less than 25000 g/mol.

18. The liquid composition according to claim 14, wherein the functionalized ?-conjugated polythiophene is present in the liquid composition in the form of particles, the particles being characterized by i) a d.sub.50-value (weight average particle diameter) in the range from 1 to 100 nm, and ii) a d.sub.90-value of less than 3.5?d.sub.50.

19. A process for producing a liquid composition comprising functionalized ?-conjugated polythiophenes, the process comprising i) providing a liquid phase comprising a) thiophene monomers of the general formula (I) ##STR00018## wherein X,Y and A are as defined in claim 1, and wherein the liquid phase comprises a mixture of thiophene monomers of formula (Ia) and thiophene monomers of formula (Ib) ##STR00019## and wherein the content of thiophene monomers of formula (Ib) is less than 18 wt.-%, and the content of thiophene monomers of formula (Ia) is more than 82 wt. %, in each case based on the total weight of the thiophene monomers in the liquid phase, wherein the content of thiophene monomers of formula (Ia) and the content of thiophene monomers of formula (Ib) equal 100 wt.-%; b) an oxidizing agent; and c) a solvent; and ii) oxidatively polymerizing the thiophene monomers of formula (Ia) and (Ib) to obtain the liquid composition.

20. The process according to claim 19, wherein the content of thiophene monomers of formula (Ib) is at least 0.2 wt.-%, based on the total weight of the thiophene monomers in the liquid phase.

21. A liquid composition, obtained by the process according to claim 19.

22. A liquid composition comprising a functionalized ?-conjugated polythiophene, wherein the polythiophene comprises repeating units of formula (I) ##STR00020## wherein X and Y are identical or different and are independently selected from O, S, and NR.sup.1, wherein R.sup.1 is hydrogen or an aliphatic or aromatic residue having 1 to 18 carbon atoms; and A is an organic residue carrying an anionic functional group; and wherein the functionalized ?-conjugated polythiophene comprises repeating units of formula (Ia) and repeating units of formula (Ib) ##STR00021## and wherein the content of repeating units of formula (Ib) is less than 18 wt. %, and the content of repeating units of formula (Ia) is more than 82 wt.-%, in each case based on the total weight of the functionalized ?-conjugated polythiophene, wherein the content of repeating units of formula (Ia) and the content of repeating units of formula (Ib) equal 100 wt.-%.

23. The liquid composition according to claim 22, wherein the content of repeating units of formula (Ib) is at least 0.2 wt. %, based on the total weight of the functionalized ?-conjugated polythiophene.

24. The liquid composition according to claim 13, wherein a conductive layer made by the liquid composition has a conductivity of more than 12 S/cm.

25. A process for the production of a capacitor, comprising: I) providing an electrode body of an electrode material, wherein a dielectric covers one surface of this electrode material at least partly under formation of an anode body; and II) introducing a liquid composition according to claim 13 into at least a part of the electrode body.

26. A capacitor obtained by the process according to claim 25.

27. An electronic device comprising a conductive layer, wherein the conductive layer comprises liquid composition according to claim 13.

28. The electronic device according to claim 27, wherein the electronic device is selected from photoconductive cells, photoresistors, photoswitches, phototransistors, phototubes, IR detectors, photovoltaic device, solar cells, coating materials for memory storage devices, field effect resistance devices, anti-static films, biosensors, electrochromic devices, solid electrolyte capacitors, energy storage devices, touch panels and electromagnetic shielding.

29. The electronic device according to claim 28, wherein the conductive layer is a solid electrolyte layer in a solid electrolyte capacitor.

30. The liquid composition according to claim 14, wherein X and Y are O; and A is (CH.sub.2).sub.mCR.sup.2R.sup.3(CH.sub.2).sub.n; wherein R.sup.2 is hydrogen or (CH.sub.2).sub.sZ(CH.sub.2).sub.pSO.sub.3.sup.?M.sup.+, R.sup.3 is (CH.sub.2).sub.sZ(CH.sub.2).sub.pSO.sub.3.sup.?M.sup.+, Z is O, S or CH.sub.2, M.sup.+ is a cation, m and n are identical or different and are independently an integer from 0 to 3, s is an integer from 0 to 10 and p is an integer from 1 to 18.

31. The liquid composition according to claim 14, wherein X and Y are O; and A is (CH.sub.2)CR.sup.2R.sup.3(CH.sub.2).sub.n; wherein R.sup.2 is hydrogen, R.sup.3 is (CH.sub.2).sub.2O(CH.sub.2).sub.pSO.sub.3.sup.?M.sup.+, M.sup.+ is Na.sup.+ or K.sup.+, n is 0 or 1, s is 0 or 1, and p is 4 or 5.

32. The liquid composition according to claim 14, wherein X and Y are O; and A is (CH.sub.2CHR); wherein R is (CH.sub.2).sub.tOAr[(W).sub.nSO.sub.3.sup.?M.sup.+].sub.v, wherein Ar is an optionally substituted C.sub.6-C.sub.20 arylene group; W is an optionally substituted C.sub.1-C.sub.6 alkylene group; M.sup.+ is H.sup.+, an alkali cation selected from the group consisting of Li.sup.+, Na.sup.+, and K.sup.+, NH(R.sup.1).sub.3 or HNC.sub.5H.sub.5, wherein each R.sup.1 group is, independently, a hydrogen atom or an optionally substituted C.sub.1-C.sub.6 alkyl group; t is an integer of 0 to 6; u is an integer of 0 or 1; and v is an integer of 1 to 4.

33. The liquid composition according to claim 22, wherein X and Y are O; and A is (CH.sub.2).sub.mCR.sup.2R.sup.3(CH.sub.2).sub.n; wherein R.sup.2 is hydrogen or (CH.sub.2).sub.sZ(CH.sub.2).sub.pSO.sub.3.sup.?M.sup.+, R.sup.3 is (CH.sub.2).sub.sZ(CH.sub.2).sub.pSO.sub.3.sup.?M.sup.+, Z is O, S or CH.sub.2, M.sup.+ is a cation, m and n are identical or different and are independently an integer from 0 to 3, s is an integer from 0 to 10 and p is an integer from 1 to 18.

34. The liquid composition according to claim 22, wherein X and Y are O; and A is (CH.sub.2)CR.sup.2R.sup.3(CH.sub.2).sub.n; wherein R.sup.2 is hydrogen, R.sup.3 is (CH.sub.2).sub.2O(CH.sub.2).sub.pSO.sub.3.sup.?M.sup.+, W is Na.sup.+ or K.sup.+, n is 0 or 1, s is 0 or 1, and p is 4 or 5.

35. The liquid composition according to claim 22, wherein X and Y are O; and A is (CH.sub.2CHR); wherein R is (CH.sub.2).sub.tOAr[(W).sub.nSO.sub.3.sup.?M.sup.+].sub.v, wherein Ar is an optionally substituted C.sub.6-C.sub.20 arylene group; W is an optionally substituted C.sub.1-C.sub.6 alkylene group; M.sup.+ is H.sup.+, an alkali cation selected from the group consisting of Li.sup.+, Na.sup.+, and K.sup.+, NH(R.sup.1).sub.3 or HNC.sub.5H.sub.5, wherein each R.sup.1 group is, independently, a hydrogen atom or an optionally substituted C.sub.1-C.sub.6 alkyl group; t is an integer of 0 to 6; u is an integer of 0 or 1; and v is an integer of 1 to 4.

Description

EXAMPLES

[0255] For the preparation of a PEDOT-S solutions as described below, the sodium salt of 4-(2,3-dihydrothieno-[3,4-b][1,4]dioxin-2-ylmethoxy)-1-butanesulphonic acid (EDOT-S) was prepared as described by Chevrot et al. (J. Electroanal. Chem. 1998, 443, 217-226) and employed as the monomer.

Synthesis Example 1

Not According to the Present Invention

[0256] A 3 L jacketed beaker made of glass is equipped a mechanical stirrer, a thermometer and a nitrogen flow.

[0257] Component A

[0258] In this beaker 243.6 g (0.9 mol) iron(III)chloride were dissolved in 800 g of deionized water and nitrogen was blown through the solution for 30 minutes while stirring until the oxygen content was below 0.25 mg/l.

[0259] Component B

[0260] In a separate glass beaker 100 g EDOT-S sodium salt (0.29 mol) were dissolved in 1200 g of deionized water. Nitrogen was blown through this solution via a flexible tube until the oxygen content was below 0.25 mg/l.

[0261] Component B was added to component A while stirring. The thus obtained mixture was heated up to 90-95? C. within 6 hours and was kept at this temperature for additional 15 hours. After the reaction was completed, the reaction mixture was filled up to a volume of 10 L by adding deionized water and was subsequently treated by means of ultrafiltration (Pall Microza SLP 1053 with a cut-off of 10000 g/mol), whereby 8 L of water were removed. This procedure was repeated 6 times in order to remove the inorganic salts.

[0262] The thus obtained dispersion was characterized by a conductivity of 0.05 S/cm and a solid content of 1.62 wt.-%.

Synthesis Example 2

Not According to the Present Invention

[0263] A 3 L jacketed tank made of stainless steel is equipped a mechanical stirrer, a ventilation valve at the upper lid, a material inlet that can be closed and a thermometer.

[0264] Component A

[0265] Into this tank 2000 g of deionized water, 16.0 g of a 10 wt.-% aqueous iron(III) sulfate solution and 100 g of EDOT-S sodium salt (0.29 mol) were introduced. The stirrer was operated at 50 rpm, the temperature was adjusted to 20? C. and the inner pressure was reduced to 100 hPa. The pressure in the tank was subsequently raised to atmospheric pressure, followed by a further reduction of a pressure to 25 hPa in order to expel the oxygen.

[0266] Component B

[0267] In a separate glass beaker 78.5 g sodium peroxodisulfate were dissolved in 200 ml water and nitrogen was blown through the solution for 30 minutes while stirring until the oxygen content was below 0.25 mg/l.

[0268] Component B was then sucked into the tank. The material inlet was then closed and the inner pressure of the tank was adjusted to 25 hPa by means of a vacuum pump. The reaction was continued for 19 hours under this reduced pressure. After the reaction was completed, the reaction mixture was filled up to a volume of 10 L by adding deionized water and was subsequently treated by means of ultrafiltration (Pall Microza SLP 1053 with a cut-off of 10000 g/mol), whereby 8 L of water were removed. This procedure was repeated 6 times in order to remove the inorganic salts.

[0269] The thus obtained dispersion was characterized by a conductivity of 0.09 S/cm and a solid content of 1.05 wt.-%.

Synthesis Example 3

According to the Present Invention

[0270] A 3 L jacketed tank made of stainless steel is equipped a mechanical stirrer, a ventilation valve at the upper lid, a material inlet that can be closed and a thermometer.

[0271] Component A

[0272] Into this tank 2000 g of deionized water, 16.0 g of a 10 wt.-% aqueous iron(III) sulfate solution, 5.7 g sulfuric acid (95 wt.-%) and 100 g of EDOT-S sodium salt (0.29 mol) were introduced. The stirrer was operated at 50 rpm, the temperature was adjusted to 20? C. and the inner pressure was reduced to 100 hPa. The pressure in the tank was subsequently raised to atmospheric pressure, followed by a further reduction of a pressure to 25 hPa in order to expel the oxygen.

[0273] Component B

[0274] In a separate glass beaker 78.5 g sodium peroxodisulfate were dissolved in 200 ml water and nitrogen was blown through the solution for 30 minutes while stirring until the oxygen content was below 0.25 mg/l.

[0275] Component B was then sucked into the tank. The material inlet was then closed and the inner pressure of the tank was adjusted to 25 hPa by means of a vacuum pump. The initial pH of the reaction solution was 1.9 and the reaction was continued for 19 hours under this reduced pressure. After the reaction was completed, the reaction mixture was filled up to a volume of 10 L by adding deionized water and was subsequently treated by means of ultrafiltration (Pall Microza SLP 1053 with a cut-off of 10000 g/mol), whereby 8 L of water were removed. This procedure was repeated 6 times in order to remove the inorganic salts.

[0276] The thus obtained composition was characterized by a conductivity of 27 S/cm and a solid content of 1.22 wt.-%. The composition was further concentrated by means of ultra filtration until a solid content of 2.4 wt.-% was reached.

Synthesis Example 4

Preparation of a PEDOT/PSS-Dispersion; Not According to the Present Invention

[0277] 868 g of deionized water and 330 g of an aqueous polystyrenesulphonic acid solution having an average molecular weight of 70000 g/mol and a solids content of 3.8 wt.-% were initially introduced into a 2 l three-necked flask with a stirrer and internal thermometer. The reaction temperature was kept between 20 and 25? C. 5.1 g of 3,4-ethylenedioxythiophene were added, while stirring. The solution was stirred for 30 min. 0.03 g of iron(III) sulphate and 9.5 g of sodium persulphate were then added and the solution was stirred for a further 24 h. After the reaction had ended, for removal of inorganic salts 100 ml of a strongly acid cation exchanger and 250 ml of a weakly basic anion exchanger were added and the solution was stirred for a further 2 h. The ion exchanger was filtered off. The poly(3,4-ethylenedioxythiophene)/polystyrenesulphonate dispersion was homogenized with a high pressure homogenizer ten times under a pressure of 700 bar. The dispersion was subsequently concentrated to a solids content of 2.5% and then additionally homogenized another five times under a pressure of 1500 bar.

Synthesis Example 5

Preparation of a PEDOT-S Composition According to the Prior Art

[0278] 0.496 g of EDOT-S (1.5 mmol) were dissolved in 18 ml of dist. water under argon. 0.97 g (6.0 mmol) of FeCl.sub.3 was then added in one portion. Thereafter, the solution was stirred at room temperature for 8 h, and heated at 100? C. for 3 h, cooled and worked up. For working up, the solution was diluted to about 3 wt.-% with dist. water, 9 g of Lewatit? S100 and 9 g of Lewatit? MP 62 were added and the mixture was stirred at room temperature for 4 h. After the ion exchangers had been filtered off, a dark blue polymer solution having a solids content of 2.71% was obtained.

Comparative Example 1

Preparation of a Capacitor Pursuant to WO 2014/048562 A2

[0279] 45 g of the PEDOT/PSS dispersion from Synthesis Example 4, 45 g of the PEDOT-S composition from Synthesis Example 5 and 10 g of polyethylene glykol 400 (PEG-400) were mixed and the pH was adjusted to 3.0 using ammonia (dispersion A).

[0280] A porous aluminium foil, formed at 36 V, having dimensions of 200 mm?5 mm (anode foil) and a porous aluminium foil having dimensions of 210 mm?3 mm (cathode foil) were each provided with a contact wire and were then wound up together with two cellulose separator papers and fixed with an adhesive tape. 20 of these oxidized electrode bodies were produced. The separator paper of the oxidized electrode bodies was then carbonized in an oven at 300? C.

[0281] The oxidized electrode bodies were impregnated in dispersion A for 15 minutes. Thereafter, drying was carried out at 120? C. for 20 min and then at 150? C. for 20 min. The impregnation and drying were carried out a further time. The mean electrical values have been determined.

Example 1

Preparation of a Capacitor Pursuant to WO 2014/048562 A2

[0282] 45 g of the PEDOT/PSS dispersion from Synthesis Example 4, 45 g of the PEDOT-S composition from Synthesis Example 3 and 10 g of polyethylene glykol 400 (PEG-400) were mixed and the pH was adjusted to 3.0 using ammonia (dispersion B).

[0283] Capacitors were prepared pursuant to the procedure in Comparative Example 1. The mean electrical values have been determined and the resultsnormalized to the Comparative Example 1are shown in Table 1.

TABLE-US-00001 TABLE 1 CAP ESR Comparative Example 1 1.00 1.00 Example 1 1.01 0.53

Synthesis Example 6

Preparation of a PEDOT/PSS Dispersion for a Polymeric Outer Layer

[0284] 1736 g of deionized water and 660 g of an aqueous polystyrenesulphonic acid solution having an average molecular weight of 70000 g/mol and a solids content of 3.8 wt.-% were initially introduced into a 5 l glass reactor with a stirrer and thermometer. The reaction temperature was kept between 20 and 25? C. 10.2 g of 3,4-ethylenedioxythiophene were added, while stirring. The solution was stirred for 30 minutes. 0.06 g of iron(III) sulphate and 19 g of sodium persulphate were then added and the solution was stirred for a further 24 hours. After the reaction had ended, for removal of inorganic salts 200 ml of a strongly acid cation exchanger and 500 ml of a weakly basic anion exchanger were added and the solution was stirred for a further 2 h. The ion exchanger was filtered off. The dispersion obtained achieved a solids content of 1.5% by subsequent concentration.

[0285] 160 g of this dispersion, 28 g of water, 6 g of a sulpho-polyester (Eastek 1100, solids content 30%, average molecular weight 10000-15000, Eastman), 8 g of dimethylsulphoxide, 1 g of 3-glycidoxypropyltrimethoxysilane (Silquest A-187, OSi Specialties) and 0.4 g of wetting agent (Dynol 604, Air Products) were mixed intensively for one hour in a glass beaker with a stirrer.

Synthesis Example 7

Preparation of a Crosslinking Agent Solution

[0286] 4.0 g of p-toluenesulphonic acid monohydrate, 1.7 g of 1,10-diaminodecane and 95.5 g of water were mixed intensively in a glass beaker with a stirrer.

Synthesis Example 8

Production of an Electrode Body for a Tantalum Electrolytic Capacitor

[0287] Tantalum powder having a specific capacitance of 18000 CV/g was pressed to pellets with inclusion of a tantalum wire and sintered in order to form a porous anode body having dimensions of 1.5 mm?2.9 mm?4.0 mm. 5 of these porous anode bodies were anodized in a phosphoric acid electrolyte at 100 V to form a dielectric, in order to obtain the capacitor bodies.

Synthesis Example 9

[0288] The composition from Synthesis Example 5 was diluted to a concentration of 2.0% by addition of deionized water.

Synthesis Example 10

[0289] The composition from Synthesis Example 3 was diluted to a concentration of 2.0% by addition of deionized water.

Comparative Example 2

[0290] The capacitor bodies from Synthesis Example 8 were impregnated in the composition from Synthesis Example 9 for 1 min. Thereafter, drying was carried out at 120? C. for 10 min. The impregnation and drying were carried out nine further times.

[0291] The capacitor bodies were then impregnated in the solution from Synthesis Example 7. Thereafter, drying was carried out at 120? C. for 10 min. The capacitor body was then impregnated in the dispersion from Synthesis Example 6. Thereafter, drying was carried out at 120? C. for 10 min.

[0292] The capacitor bodies were then impregnated in the solution from Synthesis Example 7. Thereafter, drying was carried out at 120? C. for 10 min. The capacitor body was then impregnated in the dispersion from Synthesis Example 6. Thereafter, drying was carried out at 120? C. for 10 min.

[0293] The capacitor bodies were then impregnated in the solution from Synthesis Example 7. Thereafter, drying was carried out at 120? C. for 10 min. The capacitor body was then impregnated in the dispersion from Synthesis Example 6. Thereafter, drying was carried out at 120? C. for 10 min.

[0294] The capacitor bodies were then covered with a graphite layer and thereafter with a silver layer in order to obtain the finished capacitors in this way.

[0295] The mean values for the electrical parameters (CAP, ESR) have been determined.

Example 2

[0296] The treatment of the capacitor bodies was carried out as described in Comparative Example 2, but the composition from Synthesis Example 10 was used instead of the composition from Synthesis Example 9.

[0297] The mean values for the electrical parameters (CAP, ESR) have been determined and the resultsnormalized to the Comparative Example 2are shown in table 2.

TABLE-US-00002 TABLE 2 CAP ESR Comparative Example 2 1.00 1.00 Example 2 1.15 0.25

Synthesis Example 11

Not According to the Present Invention

[0298] 0.496 g of EDOT-S (1.5 mmol) were dissolved in 18 ml of dist. water under argon. 0.97 g (6.0 mmol) of FeCl.sub.3 was then added in one portion. Thereafter, the solution was stirred at room temperature for 8 h, and heated at 100? C. for 3 h, cooled and worked up. For working up, the solution was diluted to 1 wt.-% with dist. water, 9 g of Lewatit? S100 and 9 g of Lewatit? MP 62 were added and the mixture was stirred at room temperature for 4 h. After the ion exchangers had been filtered off, a dark blue polymer solution having a solids content of 1 wt.-% was obtained. In the thus obtained composition the solid content was adjusted to 2.15 wt.-% by means of evaporation.

Synthesis Example 12

According to the Present Invention

[0299] A 3 L jacketed tank made of stainless steel is equipped a mechanical stirrer, a ventilation valve at the upper lid, a material inlet that can be closed and a thermometer.

[0300] Component A

[0301] Into this tank 2000 g of deionized water, 8.0 g of a 10 wt.-% aqueous iron(III) sulfate solution, 2.9 g sulfuric acid (95 wt.-%) and 50 g of EDOT-S sodium salt (0.15 mol) were introduced. The stirrer was operated at 50 rpm, the temperature was adjusted to 20? C. and the inner pressure was reduced to 100 hPa. The pressure in the tank was subsequently raised to atmospheric pressure, followed by a further reduction of a pressure to 25 hPa in order to expel the oxygen.

[0302] Component B

[0303] In a separate glass beaker 39.3 g sodium peroxodisulfate were dissolved in 200 ml water and nitrogen was blown through the solution for 30 minutes while stirring until the oxygen content was below 0.25 mg/l.

[0304] Component B was then sucked into the tank. The material inlet was then closed and the inner pressure of the tank was adjusted to 25 hPa by means of a vacuum pump. The initial pH of the reaction solution was 1.9 and the reaction was continued for 19 hours under this reduced pressure. After the reaction was completed, 600 g Lewatit Monoplus S 108H and 500 g Lewatit MP62 (Lanxess AG, Cologne) were added and stirred with a mechanical stirrer. After 6 hours the Lewatit was removed by filtration.

[0305] The sample was concentrated by means of rotary evaporator until a solid content of >2 wt.-% was reached. The thus obtained composition was characterized by a solid content of 2.14 wt.-%.

Synthesis Example 13

According to the Present Invention

[0306] A 3 L jacketed tank made of stainless steel is equipped a mechanical stirrer, a ventilation valve at the upper lid, a material inlet that can be closed and a thermometer.

[0307] Component A

[0308] Into this tank 2000 g of deionized water, 16.0 g of a 10 wt.-% aqueous iron(III) sulfate solution, 5.7 g sulfuric acid (95 wt.-%) and 100 g of EDOT-S sodium salt (0.29 mol) were introduced. The stirrer was operated at 50 rpm, the temperature was adjusted to 20? C. and the inner pressure was reduced to 100 hPa. The pressure in the tank was subsequently raised to atmospheric pressure, followed by a further reduction of a pressure to 25 hPa in order to expel the oxygen.

[0309] Component B

[0310] In a separate glass beaker 78.5 g sodium peroxodisulfate were dissolved in 200 ml water and nitrogen was blown through the solution for 30 minutes while stirring until the oxygen content was below 0.25 mg/l.

[0311] Component B was then sucked into the tank. The material inlet was then closed and the inner pressure of the tank was adjusted to 25 hPa by means of a vacuum pump. The initial pH of the reaction solution was 1.9 and the reaction was continued for 19 hours under this reduced pressure. After the reaction was completed, 1100g Lewatit Monoplus S 108H and 1000g Lewatit MP62 (Lanxess AG, Cologne) were added and stirred with a mechanical stirrer. After 6 hours the Lewatit was removed by filtration.

[0312] The thus obtained composition was characterized by a solid content of 1.19 wt.-%. The composition was further concentrated by means of rotary evaporator until a solid content of >2 wt.-% was reached. The thus obtained composition was characterized by a solid content of 2.15% and a conductivity of 41 S/cm.

[0313] The mass average molecular weight M.sub.w and the molar average molecular weight M.sub.n of the compositions obtained in Synthesis Example 11, Synthesis Example 12 and Synthesis Example 13 are shown in the following table 3:

TABLE-US-00003 TABLE 3 M.sub.w M.sub.n M.sub.w/M.sub.n Synthesis Example 11 23300 g/mol 5300 g/mol 4 Synthesis Example 12 79000 g/mol 8400 g/mol 9 Synthesis Example 13 204000 g/mol 9500 g/mol 21

Comparative Example 3

[0314] An aluminium capacitor was prepared as in Comparative Example 1 with the sole difference that instead of the composition from Synthesis Example 5 the composition from Synthesis Example 11 has been used.

Example 3

[0315] An aluminium capacitor was prepared as in Example 1 with the sole difference that instead of the composition from Synthesis Example 3 the composition from Synthesis Example 12 has been used.

Example 4

[0316] An aluminium capacitor was prepared as in Example 1 with the sole difference that instead of the composition from Synthesis Example 3 the composition from Synthesis Example 13 has been used.

[0317] The mean values for the electrical parameters (CAP, ESR) are shown in table 4, wherein the values were normalized to the Comparative Example 3. Also shown are the ESR-values of the capacitors after they have been stored for 500 hours at 85? C. and 85% relative humidity (the values are normalized to the corresponding values before storage under these conditions).

TABLE-US-00004 TABLE 4 ESR CAP ESR after 500 h at 85? C./85% rh Comparative Example 3 1.0 1.0 137.1 Example 3 1.0 0.9 23.8 Example 4 1.0 0.8 9.5

[0318] These results clearly show that when using a PEDOT-S-composition having a high M.sub.w/M.sub.n-value of larger than 6 for the preparation of a solid electrolyte layer in a capacitor, not only the ESR-value can be improved (as can be seen in the third column of table 4), but also the stability when the capacitor is stored at high temperatures and a high relative humidity. As can be seen in column 4 of table 4, the ESR-value increases to a lower extent in a capacitor the solid electrolyte layer of which has been prepared with a PEDOT-S-composition according to the present invention (i. e. with a PEDOT-S-composition having a M.sub.w/M.sub.n-value >6), compared to a capacitor the solid electrolyte layer of which has been prepared with a PEDOT-S-composition according to the prior art.

Synthesis Example 14

Production of an Electrode Body for a Tantalum Electrolytic Capacitor

[0319] Tantalum powder having a specific capacitance of 30000 CV/g was pressed to pellets with inclusion of a tantalum wire and sintered in order to form a porous anode body having dimensions of 1.4 mm?2.8 mm?3.9 mm. 5 of these porous anode bodies were anodized in a phosphoric acid electrolyte at 60 V to form a dielectric, in order to obtain the capacitor bodies.

Comparative Example 4

[0320] A tantalum electrolytic capacitor was prepared as in Comparative Example 2 with the differences that instead of the capacitor bodies from Synthesis Example 8 the capacitor bodies from Synthesis Example 14 has been used and that instead of the composition from Synthesis Example 9 the composition from Synthesis Example 11 has been used.

Example 5

[0321] A tantalum electrolytic capacitor was prepared as in Example 2 with the differences that instead of the capacitor bodies from Synthesis Example 8 the capacitor bodies from Synthesis Example 14 has been used and that instead of the composition from Synthesis Example 10 the composition from Synthesis Example 12 has been used.

Example 6

[0322] A tantalum electrolytic capacitor was prepared as in Example 2 with the differences that instead of the capacitor bodies from Synthesis Example 8 the capacitor bodies from Synthesis Example 14 has been used and that instead of the composition from Synthesis Example 10 the composition from Synthesis Example 13 has been used.

[0323] The mean values for the electrical parameters (CAP, ESR) are shown in table 5, wherein the values were normalized to the Comparative Example 4.

TABLE-US-00005 TABLE 5 CAP ESR Comparative Example 4 1.00 1.00 Example 5 1.00 0.57 Example 6 1.17 0.26

[0324] These results clearly show that when using a PEDOT-S-composition having a high M.sub.w/M.sub.n-value of larger than 6 for the preparation of a solid electrolyte layer in a capacitor, both the capacitance and the ESR-value can be improved.

Synthesis Example 15

Not According to the Present Invention

[0325] A 3 L jacketed tank made of stainless steel is equipped a mechanical stirrer, a ventilation valve at the upper lid, a material inlet that can be closed and a thermometer.

[0326] Component A

[0327] Into this tank 2000 g of deionized water, 16.0 g of a 10 wt.-% aqueous iron(III) sulfate solution, 5.7 g sulfuric acid (95 wt.-%) and 100 g of EDOT-S sodium salt (0.29 mol) which contains 20 wt.-% PRODOT-S sodium salt (determined by HPLC) were introduced. The stirrer was operated at 50 rpm, the temperature was adjusted to 20? C. and the inner pressure was reduced to 100 hPa. The pressure in the tank was subsequently raised to atmospheric pressure, followed by a further reduction of a pressure to 25 hPa in order to expel the oxygen.

[0328] Component B

[0329] In a separate glass beaker 78.5 g sodium peroxodisulfate were dissolved in 200 ml water and nitrogen was blown through the solution for 30 minutes while stirring until the oxygen content was below 0.25 mg/l.

[0330] Component B was then sucked into the tank. The material inlet was then closed and the inner pressure of the tank was adjusted to 25 hPa by means of a vacuum pump. The initial pH of the reaction solution was 1.9 and the reaction was continued for 19 hours under this reduced pressure. After the reaction was completed, the reaction mixture was filled up to a volume of 10 L by adding deionized water and was subsequently treated by means of ultrafiltration (Pall Microza SLP 1053 with a cut off of 10000 g/mol), whereby 8 L of water were removed. This procedure was repeated 6 times in order to remove the inorganic salts.

[0331] The resulting dispersion had a solid content of 1.47 wt.-% and was further concentrated by means of rotary evaporator to a solid content of 2.96 wt.-%.

Synthesis Example 16

According to the Present Invention

[0332] A PEDOT-S-composition has been prepared in the same way as in Synthesis Example 15, with the sole difference that an EDOT-S sodium salt which contains 10 wt.-% PRODOT-S sodium salt has been used.

Comparative Example 5

[0333] A tantalum electrolytic capacitor was prepared as in Comparative Example 4 with the sole difference that instead of the composition from Synthesis Example 11 the composition from Synthesis Example 15 has been used.

Example 7

[0334] A tantalum electrolytic capacitor was prepared as in Example 5 with the sole difference that instead of the composition from Synthesis Example 10 the composition from Synthesis Example 16 has been used.

[0335] The mean values for the electrical parameters (CAP, ESR) are shown in table 6, wherein the values were normalized to the Comparative Example 5.

TABLE-US-00006 TABLE 6 CAP ESR Comparative Example 5 1.00 1.00 Example 7 1.00 0.77

[0336] These results clearly show that when using a PEDOT-S-composition having a PRODOT-S-content of only 10 wt.-% for the preparation of a solid electrolyte layer in a tantalum electrolytic capacitor, the ESR-value is significantly lower compared to a tantalum electrolytic capacitor the solid electrolyte of which has been prepared by means of a PEDOT-S-composition that is based on an EDOT-S-monomer having a PRODOT-S-content of 20 wt.-%.