JP2003158043A - Conductive polymer and solid electrolytic capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive polymer with excellent conductivity and heat resistance, and to provide a solid electrolytic capacitor highly reliable under high-temperature and high-humidity conditions by using this conductive polymer as a solid electrolyte. SOLUTION: There is provided a conductive polymer by adding as a dopant at least one or more sulfonic acids selected from tetrahydronaphthalenesulfonic acid containing one or more sulfone groups or alkyltetrahydronaphthalenesulfonic acid containing one or more alkyl groups having 1-18 carbon atoms and one or more sulfone groups. As a monomer for synthesizing the conductive polymer, at least one or more selected from pyrrole, thiophene, and aniline and derivatives thereof are preferable. A solid electrolytic capacitor is provided by using this conductive polymer as a solid electrolyte.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conductive polymer and a solid electrolytic capacitor using the conductive polymer as a solid electrolyte.

[0002]

2. Description of the Related Art Due to its high conductivity, conductive polymers are used as solid electrolytes for solid electrolytic capacitors such as aluminum capacitors and tantalum capacitors.

As conductive polymers for such applications, those synthesized by chemical oxidative polymerization or electrolytic oxidative polymerization of pyrrole, thiophene, aniline or their derivatives are used.

Organic sulfonic acids are mainly used as dopants in the oxidative polymerization, and among them, aromatic sulfonic acids are often used.

However, since the alkyl chain of alkylbenzene, which is the starting material for aromatic sulfonic acid, is a mixed alkyl and is not constant as a single compound in the case of a long chain, the conductivity of the resulting conductive polymer is low. It causes variation. For example, even with a single molecular weight such as dodecylbenzenesulfonic acid (molecular weight 326), the presence of structural isomers affects the electrical properties. In addition, the long-chain type aromatic sulfonic acid having a long-chain alkyl group has a large molecular size, so that it is difficult to dope, and as a result, sufficient conductivity cannot be obtained in the initial polymerization stage.

On the other hand, short-chain aromatic sulfonic acids such as benzene sulfonic acid (molecular weight 158) and toluene sulfonic acid (molecular weight 172) have a small molecular size and are easily doped, so that good conductivity is obtained in the initial polymerization stage. However, due to its small molecular size, dedoping is likely to occur, and particularly when left under high temperature and high humidity conditions, a remarkable decrease in conductivity is observed.

From the above situation, good conductivity is obtained in the initial polymerization stage, and even if it is left under the condition of high temperature and high humidity, no significant decrease in conductivity is observed, and there is little variation in conductivity. There is a need for a dopant that can form a conductive polymer.

Therefore, in order to meet the above demands,
As a dopant for conductive polymer, Japanese Patent Publication No. 6-8259
The use of naphthalene sulfonic acid has been proposed in JP-A-0. However, the polymer using naphthalene sulfonic acid as a dopant cannot be said to be sufficiently satisfactory in terms of conductivity and heat resistance.

[0009]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a conductive polymer having excellent conductivity and heat resistance, which is solid-stated. It is an object of the present invention to provide a solid electrolytic capacitor which is used as an electrolyte and has high reliability under high temperature and high humidity conditions.

[0010]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that tetrahydronaphthalene sulfonic acid containing at least one sulfonic acid,
Or containing one or more alkyl groups having 1 to 18 carbon atoms,
It has also been found that a conductive polymer containing, as a dopant, an alkyltetrahydronaphthalenesulfonic acid containing one or more sulfone groups has a feature capable of solving the above problems.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Tetrahydronaphthalenesulfonic acid containing one or more of the above-mentioned sulfonic acids and having 1 to 1 carbon atoms
Specific examples of the alkyl tetrahydronaphthalene sulfonic acid containing one or more alkyl groups of 8 and one or more sulfonic acids include, for example, tetrahydronaphthalene monosulfonic acid, tetrahydronaphthalene disulfonic acid, diisopropyl tetrahydronaphthalene monosulfone. Acid, monobutyl tetrahydronaphthalene disulfonic acid, dinonyl tetrahydronaphthalene monosulfonic acid, etc. can be mentioned, but regarding the sulfonic acid moiety, whether it is a mono body, a di body, or a tri body need not be so particular. However, it may be one that is in the category of tetrahydronaphthalene sulfonic acid or alkyltetrahydronaphthalene sulfonic acid, and for example, it is mainly composed of monosulfonic acid as used in the examples, and disulfonic acid and trisulfonic acid are small. It may include.

Tetrahydronaphthalene (tetralin)
Has a structure in which a cycloalkyl ring in which one of the two aromatic rings of naphthalene is completely hydrogenated is added to a benzene ring, and thus is a monocyclic benzene or a double-membered ring. It has a completely different chemical property from naphthalene.

Tetrahydronaphthalene sulfonic acid can be synthesized by mixing the above tetrahydronaphthalene with concentrated sulfuric acid, sulfonation, neutralization with an alkaline agent such as caustic soda, and purification treatment such as crystallization separation. .

Alkyl tetrahydronaphthalene sulfonic acid is obtained by, for example, mixing butanol, tetrahydronaphthalene, concentrated sulfuric acid and fuming sulfuric acid, alkylating and sulfonation, neutralizing with an alkali agent such as caustic soda, and separating by crystallization. It can be synthesized by performing a purification treatment such as.

In the present invention, as the conductive polymer synthesizing monomer, for example, at least one selected from pyrrole, thiophene, aniline and derivatives thereof can be used.

Next, a method for synthesizing the conductive polymer of the present invention will be described.

In synthesizing the conductive polymer of the present invention, first, at least one kind of conductive polymer synthesizing monomer selected from pyrrole, thiophene, aniline and derivatives thereof is used as (alkyl) tetrahydronaphthalenesulfonic acid. It is used as a dopant for chemical oxidative polymerization or electrolytic oxidative polymerization.

In the case of chemical oxidative polymerization, the above (alkyl) tetrahydronaphthalenesulfonic acid is used as a transition metal salt, for example, a ferric salt or a cupric salt, and the metal salt and the monomer for synthesizing the conductive polymer are mixed with an organic compound. Separately preliminarily diluted with a solvent to a specific concentration, the solutions are mixed and allowed to react for a certain period of time, then washed and dried to synthesize a conductive polymer (used here) In the sulfonic acid salt, the transition metal component acts as an oxidative polymerization agent for the monomer for synthesizing the conductive polymer, and the remaining sulfonic acid component is contained in the polymer matrix, which functions as a so-called dopant). Examples of the organic solvent used in the above polymerization include methanol, ethanol, n-propanol, and n-butanol, and any of the above solvents may be used in the washing.

In the case of electrolytic oxidative polymerization, the above (alkyl) tetrahydronaphthalenesulfonic acid or a salt thereof (sodium, potassium salt, etc.) and the conductive polymer synthesizing monomer are dissolved in a solvent to obtain a constant potential or a constant potential. The polymerization of the monomer is advanced under the electric current condition to synthesize the conductive polymer.
Examples of the solvent used in this electrolytic oxidative polymerization include water, methanol, ethanol, n-propanol,
Examples of the solvent include n-butanol, and any of the above solvents may be used for washing.

The electroconductive polymer thus synthesized has excellent electroconductivity and heat resistance, and therefore is useful in applications such as capacitors, batteries, antistatic sheets and anticorrosion paints. .

[0021]

EXAMPLES The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to only those illustrated in those examples. In addition, prior to the examples, tetrahydronaphthalene sulfonic acid containing one or more sulfonic acids serving as a dopant of the conductive polymer of the examples and one or more sulfones containing an alkyl group having 1 to 18 carbon atoms. Synthesis of acid-containing alkyltetrahydronaphthalenesulfonic acid is shown as Synthesis Examples 1 to 3. In the following,% indicating the concentration of a solution or dispersion is based on mass.

Synthesis Example 1 392 g of 98% sulfuric acid with stirring at a temperature of 80 ° C.
Was added dropwise to 580 g of tetrahydronaphthalene. After the dropwise addition of the sulfuric acid, the temperature of the reaction solution was raised to 120 ° C., and the temperature was maintained for 4 hours with stirring. After the reaction was completed, 300 g of distilled water was added, and only the lower layer part separated into two layers was taken out.
Tetrahydronaphthalenesulfonic acid was obtained by repeating concentration by distillation and addition of water to completely remove unreacted tetrahydronaphthalene. The tetrahydronaphthalenesulfonic acid thus obtained was mainly composed of monosulfonic acid and contained a small amount of disulfonic acid and trisulfonic acid.

Synthesis Example 2 Tetrahydronaphthalene 245 g and methanol 110 g
And mixed. Under water cooling, 975 g of 98% sulfuric acid was slowly added thereto while stirring this mixed solution. Then, it stirred for 30 minutes. Furthermore, 28% fuming sulfuric acid 124
After slowly adding g, the reaction was continued under stirring at 55 ° C. for 4 hours. After adding 300 g of n-butanol and 500 g of distilled water to the obtained reaction liquid, the upper layer portion obtained by separating the two layers was taken out. The sulfuric acid content was removed from the reaction solution by adding 500 g of distilled water again to the upper layer portion taken out, and taking out the upper layer separated into two layers. The reaction solution obtained was concentrated by distillation, and the operation of adding water was repeated 6 times to replace the solvent of the reaction solution with water from n-butanol. Further, in order to remove unreacted tetrahydronaphthalene and methyltetrahydronaphthalene, 500 ml of petroleum ether was added, and after sufficiently stirring, the mixture was allowed to stand. The lower layer separated from the two layers was taken out, concentrated by distillation, and water-insoluble components were removed by repeating the operation of adding water to obtain methyltetrahydronaphthalenesulfonic acid. The methyltetrahydronaphthalenesulfonic acid thus obtained was mainly composed of monosulfonic acid and contained a small amount of disulfonic acid and trisulfonic acid.

Synthetic Example 3 The same operation as in Synthetic Example 2 was repeated except that 263 g of n-butanol was added instead of methanol to obtain an aqueous butyltetrahydronaphthalenesulfonic acid solution. And
By neutralizing with a 5 mol / l sodium hydroxide aqueous solution, a sodium butyl tetrahydronaphthalene sulfonate aqueous solution was obtained. The butyltetrahydronaphthalenesulfonic acid obtained as described above was mainly composed of monosulfonic acid and contained a small amount of disulfonic acid and trisulfonic acid.

Example 1 First, the tetrahydronaphthalenesulfonic acid obtained in Synthesis Example 1 above was reacted with ferric hydroxide to obtain an aqueous ferric tetrahydronaphthalenesulfonic acid salt solution having a concentration of 50%.
The ferric hydroxide used was synthesized as follows.

At room temperature, 1000 ml of distilled water was used to
_{e 2 (SO 4) 3 ·} 8H 2 O and 108.6 g (0.2 m
While the solution prepared by dissolution was vigorously stirred, a 5 mol / l sodium hydroxide aqueous solution was slowly added to the solution to adjust the pH to 7, and the supernatant was removed by centrifugation to remove ferric hydroxide. A precipitate was obtained. In order to remove excess water-soluble salt, the above ferric hydroxide precipitate was dispersed in 4000 ml of distilled water, and the operation of removing the supernatant by centrifugation was repeated twice. The obtained ferric hydroxide precipitate was dispersed in 500 g of normal butanol.

Separately, 229 g of tetrahydronaphthalene sulfonic acid obtained in Synthesis Example 1 was preliminarily added to 50
It was dissolved in 0 g of normal butanol, and the ferric hydroxide dispersion prepared by the above method was added to the solution. After stirring and reacting at room temperature for 12 hours, it was distilled to obtain a normal butanol solution of a ferric tetrahydronaphthalenesulfonic acid salt having a concentration of 50%.

The concentration of the above-mentioned ferric tetrahydronaphthalenesulfonic acid salt was adjusted by adding n-butanol to a concentration of 0.5 mol / l, and then the solution was added with 3,4-
The concentration of ethylenedioxythiophene is 0.5 mol / l
The above-mentioned tetrahydronaphthalene sulfonic acid ferric salt is used as an oxidizing agent,
The chemical oxidative polymerization of 4-ethylenedioxythiophene was initiated, and 180 μl of it was immediately dropped on a 3 cm × 5 cm ceramic plate. Then, after polymerizing on the ceramic plate at a humidity of 55% and a temperature of 25 ° C. for 12 hours, the plate was put in ethanol together with a polymer film formed thereon, washed, and dried at 130 ° C. for 30 minutes. After drying, the plate was left for 5 minutes under a load of 1.5 t to make the membrane pressure uniform, and the conductivity of polyethylene dioxythiophene as a polymer was adjusted to 4
Probe-type conductivity meter (Mitsubishi Chemical Corporation MCP-T6
00). The results are shown in Table 1 below.

Example 2 The same procedure as in Example 1 was repeated except that 244 g of methyltetrahydronaphthalenesulfonic acid obtained in Synthesis Example 2 was used in place of the tetrahydronaphthalenesulfonic acid obtained in Synthesis Example 1. The chemical oxidative polymerization of oxythiophene was performed, and the conductivity of the obtained polyethylenedioxythiophene was measured. The results are shown in Table 1 below.

Comparative Example 1 Chemical oxidative polymerization of 3,4-ethylenedioxythiophene was carried out in the same manner as in Example 1 except that 186 g of p-toluenesulfonic acid was used instead of the tetrahydronaphthalenesulfonic acid obtained in Synthesis Example 1. Then, the electrical conductivity of the obtained polyethylenedioxythiophene was measured. The results are shown in Table 1 below.

Comparative Example 2 Chemical oxidation of 3,4-ethylenedioxythiophene was carried out in the same manner as in Example 1 except that 352 g of branched dodecylbenzenesulfonic acid was used in place of the tetrahydronaphthalenesulfonic acid obtained in Synthesis Example 1. Polymerization was performed, and the conductivity of the obtained polyethylenedioxythiophene was measured. The results are shown in Table 1 below.

Comparative Example 3 The procedure of Example 3 was repeated except that 225 g of naphthalenesulfonic acid was used instead of the tetrahydronaphthalenesulfonic acid obtained in Synthesis Example 1.
The chemical oxidative polymerization of 3,4-ethylenedioxythiophene was carried out in the same manner as in Example 1, and the electrical conductivity of the obtained polyethylenedioxythiophene was measured. The results are shown in Table 1 below.

Comparative Example 4 Chemical oxidation polymerization of 3,4-ethylenedioxythiophene was carried out in the same manner as in Example 1 except that 240 g of methylnaphthalenesulfonic acid was used instead of the tetrahydronaphthalenesulfonic acid obtained in Synthesis Example 1. Then, the conductivity of the obtained polyethylenedioxythiophene was measured. The results are shown in Table 1 below.

The electrical conductivity of the polyethylenedioxythiophenes obtained in Examples 1 and 2 and Comparative Examples 1 to 4 is shown in Table 1 together with the dopant.

[0035]

[Table 1]

As shown in Table 1, the polyethylenedioxythiophenes of Examples 1 and 2 were higher in electrical conductivity and excellent in conductivity than the polyethylenedioxythiophenes of Comparative Examples 1 to 4.

That is, the polyethylenedioxythiophene of Example 1 having tetrahydronaphthalenesulfonic acid as a dopant and the polyethylenedioxythiophene of Example 2 having methyltetrahydronaphthalenesulfonic acid as a dopant have p-toluenesulfonic acid as a dopant. Polyethylenedioxythiophene of Comparative Example 1,
Polyethylenedioxythiophene of Comparative Example 2 with branched dodecylbenzenesulfonic acid as a dopant, Polyethylenedioxythiophene of Comparative Example 3 with naphthalenesulfonic acid as a dopant, and Polyethylenedioxy of Comparative Example 4 with methylnaphthalenesulfonic acid as a dopant It had higher conductivity than thiophene and was superior in conductivity.

Next, the above Examples 1 and 2 and Comparative Example 1
With respect to polyethylenedioxythiophene of Nos. 4 to 4, the rate of decrease in conductivity due to high temperature storage was examined. The results are shown in Table 2. The method of the high temperature storage test is as follows.

High temperature storage test: For the polyethylene dioxythiophene sheets of Examples 1 to 2 and Comparative Examples 1 to 4 above, the electrical conductivity was measured as described above, and then each sheet was stored in a high temperature tank at 130 ° C. Then, the sheet was taken out with time and the electrical conductivity was measured to examine the rate of decrease in electrical conductivity due to high temperature storage. Note that the rate of decrease in conductivity is the difference between the initial conductivity value (that is, the conductivity value measured before storage) minus the conductivity value after storage divided by the initial conductivity value, and the percentage (%). Indicated by. This is expressed by the following formula.

[0040]

[0041]

[Table 2]

As is clear from the results shown in Table 2, the polyethylenedioxythiophenes of Examples 1 and 2 are 2% less than the polyethylenedioxythiophenes of Comparative Examples 1 to 4.
Even after storage for 4 hours and storage for 48 hours, there was little decrease in electric conductivity and heat resistance was excellent.

That is, the polyethylenedioxythiophene of Example 1 having tetrahydronaphthalenesulfonic acid as a dopant and the polyethylenedioxythiophene of Example 2 having methyltetrahydronaphthalenesulfonic acid as a dopant have p-toluenesulfonic acid as a dopant. Polyethylenedioxythiophene of Comparative Example 1,
Polyethylenedioxythiophene of Comparative Example 2 with branched dodecylbenzenesulfonic acid as a dopant, Polyethylenedioxythiophene of Comparative Example 3 with naphthalenesulfonic acid as a dopant, and Polyethylenedioxy of Comparative Example 4 with methylnaphthalenesulfonic acid as a dopant Compared to thiophene, the decrease in conductivity due to high temperature storage was small and the heat resistance was excellent.

Example 3 In this example 3, a conductive polymer is synthesized by electrolytic oxidative polymerization and its evaluation is performed. First, a ceramic plate coated with a conductive polymer used as an anode for electrolytic oxidation polymerization was prepared. That is, a ferric p-toluenesulfonic acid salt was used as an oxidizing agent in the form of an aqueous solution, and chemical oxidative polymerization was performed in the same manner as in Example 1 to produce a ceramic plate coated with polyethylenedioxythiophene. The resulting ceramic plate (ie,
Ceramic plate coated with polyethylenedioxythiophene) is used as the anode, and stainless steel (SUS30)
4) was used as a cathode to carry out electrolytic oxidative polymerization of pyrrole as shown below.

The butyl tetrahydronaphthalene sulfonic acid sodium salt obtained in Synthesis Example 3 was adjusted in advance to a concentration of 0.04 mol / l with pure water, and pyrrole was adjusted to a concentration of 0.04 mol / l. So added. Then, using the electrode shown above, 1 mA
A polypyrrole incorporating butyltetrahydronaphthalenesulfonic acid was synthesized by electrolytically oxidatively polymerizing a constant current of / cm for 70 minutes. The obtained polypyrrole was thoroughly washed with ethanol and dried at 150 ° C. for 1 hour, and then the surface resistance was measured with a four-probe method conductivity meter (MCP-T600 manufactured by Mitsubishi Chemical Corporation). The results are shown in Table 3 below.

Comparative Example 5 Pyrrole was electrolytically oxidatively polymerized in the same manner as in Example 3 except that p-toluenesulfonic acid sodium salt was used in place of the butyltetrahydronaphthalenesulfonic acid sodium salt obtained in Synthesis Example 3. The surface resistance of the obtained polypyrrole was measured. The results are shown in Table 3 below.

Comparative Example 6 Pyrrole was electrolytically oxidatively polymerized in the same manner as in Example 3 except that a branched dodecylbenzenesulfonic acid sodium salt was used in place of the butyltetrahydronaphthalenesulfonic acid sodium salt obtained in Synthesis Example 3. The surface resistance of the obtained polypyrrole was measured. The results are shown in Table 3 below.

Comparative Example 7 Pyrrole was obtained by electrolytically oxidatively polymerizing pyrrole in the same manner as in Example 3 except that butylnaphthalenesulfonic acid sodium salt was used in place of butyltetrahydronaphthalenesulfonic acid sodium salt obtained in Synthesis Example 3. The surface resistance of the polypyrrole was measured. The results are shown in Table 3 below.

The results of measuring the surface resistance of the polypyrrole obtained in Example 3 and Comparative Examples 5 to 7 are shown in Table 3 together with the dopant.

[0050]

[Table 3]

As shown in Table 3, it was apparent that the polypyrrole of Example 3 had a smaller surface resistance and a higher electric conductivity than the polypyrroles of Comparative Examples 5 to 7.
That is, the polypyrrole of Example 3 having butyl tetrahydronaphthalene sulfonic acid as a dopant is the polypyrrole of Comparative Example 5 having p-toluene sulfonic acid as a dopant, and the polypyrrole of Comparative Example 6 having a branched dodecylbenzene sulfonic acid as a dopant and butyl. Compared to the polypyrrole of Comparative Example 7 using naphthalene sulfonic acid as a dopant, the surface resistance was small and the conductivity was excellent. In particular, the polypyrrole of Example 3 had smaller surface resistance and excellent conductivity than the polypyrrole of Comparative Example 7 using butylnaphthalenesulfonic acid as a dopant.

Next, the above-mentioned Example 3 and Comparative Examples 5-7
After measuring the surface resistance of the polypyrrole of No. 1 as described above, a high temperature storage test was conducted in the same manner as the polyethylene dioxythiophene of Example 1 and the like, and an increase in surface resistance due to high temperature storage was investigated. The results are shown in Table 4.

[0053]

[Table 4]

As shown in Table 4, the polypyrrole of Example 3 had smaller surface resistance and excellent heat resistance than those of Comparative Examples 5 to 6 after 24 hours storage and 48 hours storage. .

That is, the polypyrrole of Comparative Example 5 containing p-toluenesulfonic acid as a dopant and the polypyrrole of Comparative Example 6 containing branched dodecylbenzenesulfonic acid as a dopant were, as shown in Table 3 above, The surface resistance was not so large as compared with the polypyrrole of Example 3 using butyl tetrahydronaphthalene sulfonic acid as a dopant, but when it was stored at high temperature, the surface resistance was significantly increased as compared with the polypyrrole of Example 3. The heat resistance was poor. Further, the polypyrrole of Comparative Example 7 using butylnaphthalenesulfonic acid as a dopant did not show a significant increase in surface resistance due to high temperature storage, but as shown in Table 3 above, the surface resistance before storage was that of Example 3. It is larger than polypyrrole, and unlike the polypyrrole of Example 3, it was not possible to combine excellent conductivity and excellent heat resistance.

Examples 4 to 5 and Comparative Examples 8 to 11 After the surface of the aluminum foil was subjected to etching treatment, chemical conversion treatment was carried out, and the anode foil having the dielectric film formed thereon and the aluminum foil serving as the cathode foil were interposed via a separator. It wound and produced the capacitor element. Then, the separator portion of this capacitor element was impregnated with 3,4-ethylenedioxythiophene, and the respective ferric sulfonic acid salts obtained in the processes of Examples 1-2 and Comparative Examples 1-4 were separately separated. Was impregnated in the solution and heated at 60 ° C. for 2 hours to form a solid electrolyte layer made of polyethylenedioxythiophene. Then, it was packaged with a packaging material to obtain a solid electrolytic capacitor.

The equivalent series resistance (ESR) of the solid electrolytic capacitors of Examples 4 to 5 and Comparative Examples 8 to 11 thus produced were measured. The results are shown in Table 5 together with the type of dopant.

[0058]

[Table 5]

As shown in Table 5, the solid electrolytic capacitors of Examples 4 to 5 had a smaller ESR value than the solid electrolytic capacitors of Comparative Examples 8 to 11.

That is, the solid electrolytic capacitor of Example 4 using a conductive polymer having tetrahydronaphthalene sulfonic acid as a dopant and the conductive polymer having methyl tetrahydronaphthalene sulfonic acid as a dopant was used as a solid electrolyte. The solid electrolytic capacitor of Example 5 is a comparative example 8 in which a conductive polymer having p-toluenesulfonic acid as a dopant is used as a solid electrolyte.
Of the solid electrolytic capacitor of Comparative Example 9 in which a conductive polymer having branched dodecylbenzenesulfonic acid as a dopant was used as a solid electrolyte, and a conductive polymer having naphthalenesulfonic acid as a dopant was used as a solid electrolyte. Compared with the solid electrolytic capacitor of Comparative Example 10 and the solid electrolytic capacitor of Comparative Example 11 using a conductive polymer having methylnaphthalenesulfonic acid as a dopant as a solid electrolyte, the ESR was small and the characteristics under high temperature and high humidity conditions It was reliable.

[0061]

As described above, according to the present invention, it is possible to provide a conductive polymer having excellent conductivity and heat resistance, and using the conductive polymer as a solid electrolyte. It was possible to provide a solid electrolytic capacitor with high reliability under high temperature and high humidity conditions.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takao Tsuzuki             Takeka, 1-3-4, Funamachi, Taisho-ku, Osaka             Within the corporation F-term (reference) 4J032 BA13 BD02 CG01                 4J043 QB02 RA08 SA05 UA121                       YB05 YB38 ZA44 ZB49

Claims (3)

[Claims] 1. Tetrahydronaphthalene sulfonic acid containing at least one sulfone group, or having 1 to 18 carbon atoms.
A conductive polymer containing at least one or more sulfonic acid selected from alkyltetrahydronaphthalene sulfonic acids containing at least one alkyl group and containing at least one sulfone group as a dopant. 2. The conductive polymer according to claim 1, wherein the monomer for synthesizing the conductive polymer is at least one selected from pyrrole, thiophene, aniline and derivatives thereof. 3. A solid electrolytic capacitor using the conductive polymer according to claim 1 as a solid electrolyte.