JP2003160647A - Conductive polymer and solid electrolytic capacitor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive polymer excellent in conductivity and heat resistance, and to provide a solid electrolytic capacitor having high reliability in high temperature and high humidity conditions using the conductive polymer as a solid electrolyte. <P>SOLUTION: The conductive polymer comprises at least one sulfonic acid as a dopant selected from an alkoxy benzenesulfonic acid, an alkoxy naphthalenesulfonic acid and an alkoxy tetralinsulfonic acid including one or more 1-18C alkoxy groups and one or more sulfonic groups. The monomers for synthesizing above conductive polymer preferably include at least one or more monomers selected from pyrrole, thiophene, aniline and derivatives thereof. The solid electrolytic capacitor is composed by using the above conductive polymer as a solid electrolyte. <P>COPYRIGHT: (C)2003,JPO

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 polymers, Chemistry
Letters, 1996, 253-, Shinji
Takeoka, et. al. It has been proposed to form a conductive polymer by electrolytic oxidative polymerization using an aromatic sulfonic acid having an OH group. However, the aromatic sulfonic acid as described above generally has a weak emulsifying power and cannot completely emulsify the monomer, so that there is a problem that a uniform conductive polymer cannot be synthesized.
It is also possible to add an alkyl group separately in order to enhance the emulsifying power, but the reaction becomes complicated and it is not economical.

Further, in the case of chemical oxidative polymerization, it is necessary to finish an aromatic sulfonic acid having an alkoxyl group as an oxidizing agent into a transition metal salt such as a ferric salt or a cupric salt. Since the attached aromatic iron sulfonate has a strong chelating effect, it was not possible to prepare a uniform iron salt.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the problems in the prior art as described above, provides a conductive polymer having excellent conductivity and heat resistance, and also provides a solid polymer thereof. 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.

[0011]

The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, have 1 to 18 carbon atoms.
Conductivity containing at least one or more sulfonic acid selected from the group consisting of alkoxybenzene sulfonic acid, alkoxynaphthalene sulfonic acid, and alkoxytetraline sulfonic acid containing at least one alkoxyl group and containing at least one sulfone group It was found that the polymer has excellent electrical conductivity and excellent heat resistance, and has a feature capable of solving the above problems.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Alkoxybenzenesulfonic acid, alkoxynaphthalenesulfonic acid, and alkoxytetralinsulfonic acid containing at least one alkoxyl group having 1 to 18 carbon atoms and having at least one sulfone group. As the at least one sulfonic acid to be used, those having an alkoxyl group having 1 to 5 carbon atoms are preferable, and specific examples thereof include, for example, methoxybenzenesulfonic acid, ethoxybenzenesulfonic acid, butoxybenzenesulfonic acid, pentoxy. Benzenesulfonic acid, methoxynaphthalenesulfonic acid, ethoxynaphthalenesulfonic acid, butoxynaphthalenesulfonic acid, pentoxynaphthalenesulfonic acid, methoxytetralinsulfonic acid, ethoxytetralinsulfonic acid, butoxytetralinsulfonic acid, pentoki Such as tetralin sulfonic acid as particularly preferred.

The sulfonic acid of the alkoxy aromatic compound (benzene, naphthalene, tetralin) containing at least one alkoxyl group having 1 to 18 carbon atoms as described above and containing at least one sulfonic acid group is The aromatic compound having an alkoxyl group is mixed with concentrated sulfuric acid to be sulfonated, then neutralized with an alkaline agent such as caustic soda, and purified by crystallization separation or the like.

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

Next, the synthesis of the conductive polymer of the present invention and the solid electrolytic capacitor using the conductive polymer as a solid electrolyte will be described.

In synthesizing the electroconductive polymer of the present invention, first, at least one kind of electroconductive polymer synthesizing monomer selected from pyrrole, thiophene, aniline and their derivatives is added to the above-mentioned alkoxybenzenesulfonic acid and alkoxynaphthalene. Chemical oxidation polymerization or electrolytic oxidation polymerization is performed using sulfonic acid, alkoxytetralin sulfonic acid, or the like as a dopant.

In the case of chemical oxidative polymerization, the above-mentioned alkoxybenzenesulfonic acid, alkoxynaphthalenesulfonic acid, and alkoxytetralinsulfonic acid are used as transition metal salts such as ferric salt and cupric salt, and the metal salts and the conductive polymer are used. Synthetic monomer and organic solvent to a specific concentration,
Separately pre-diluted separately, mix the solutions and react for a certain period of time, then wash and dry to synthesize the conductive polymer (the sulfonate used here is the transition metal The 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 and 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 washing.

In the case of electrolytic oxidative polymerization, the above-mentioned alkoxybenzenesulfonic acid, alkoxynaphthalenesulfonic acid, alkoxytetralinesulfonic acid or a salt thereof (sodium salt, potassium salt, etc.) and a monomer for synthesizing a conductive polymer are dissolved in a solvent. Then, the polymerization of the monomer is advanced under the constant potential or constant 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 conductive polymer synthesized in this manner has excellent conductivity and heat resistance. The reason for this is not always clear at present, but in the case of electrolytic oxidative polymerization, the sulfonate of an alkoxyaromatic compound has a surface-active ability, so that the monomer can be uniformly emulsified, thereby providing a uniform emulsion. It is considered that such a conductive polymer is formed and excellent conductivity is obtained from the initial polymerization stage.

Further, in the case of chemical oxidative polymerization, when the sulfonic acid of the alkoxyaromatic compound is a transition metal salt such as a ferric salt or a cupric salt, there is no chelating action like the OH group. A homogeneous transition metal salt can be obtained.
When the sulfonic acid transition metal salt of the alkoxyaromatic compound is used as an oxidative polymerization agent, a uniform conductive polymer is formed, so that excellent properties can be obtained from the initial polymerization stage. Conceivable. The alkoxyl group of the dopant thus taken into the conductive polymer is easily decomposed during long-term storage, and at that time, the alkoxyl group is changed to an OH group, so that excellent heat resistance can be obtained. it is conceivable that.

As described above, the conductive polymer of the present invention is
Since it has excellent conductivity and heat resistance, it is useful in applications such as capacitors, batteries, antistatic sheets, and corrosion resistant paints.

[0022]

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. Further, prior to the examples, alkoxybenzene sulfonic acid, alkoxy containing at least one alkoxyl group having 1 to 18 carbon atoms and serving as a dopant for the conductive polymer of the examples, and containing at least one sulfonic acid. Synthetic examples 1 to 3 show synthetic examples of at least one sulfonic acid selected from naphthalene sulfonic acid and alkoxytetralin sulfonic acid. In the following,% indicating the concentration of a solution or dispersion is based on mass.

Synthesis Example 1 While stirring at room temperature, 560 g of 98% sulfuric acid was added dropwise to 600 g of methoxybenzene. After the dropwise addition of the sulfuric acid, the temperature of the reaction liquid was raised to 75 ° C., and the temperature was maintained, and the mixture was stirred for 3 hours. After the reaction is completed, 500 g of distilled water is added, 200 g of ether is added, and only the lower layer separated into two layers is taken out, and further concentration by distillation and addition of water are repeated twice to remove unreacted methoxybenzene. Thus, methoxybenzenesulfonic acid was obtained. 2mo more
Neutralization with l / l sodium hydroxide also gave the sodium salt of methoxybenzenesulfonic acid.

Synthesis Example 2 678 g of ethoxybenzene instead of methoxybenzene
The same operation as in Example 1 was carried out except that was used to obtain ethoxybenzenesulfonic acid.

Synthesis Example 3 878 g of methoxynaphthalene instead of methoxybenzene
The same operation as in Example 1 was carried out except that was used to obtain methoxynaphthalenesulfonic acid and its sodium salt.

Example 1 Fe ₂ (SO ₄ ) ₃ ··· was added to 1000 ml of distilled water at room temperature.
A solution prepared by dissolving 108.6 g (0.2 mol) of 8H ₂ O was vigorously stirred while 5 mol / l thereof was added.
Slowly add aqueous sodium hydroxide solution to pH 7
After the adjustment, the supernatant was removed by centrifugation to obtain a ferric hydroxide precipitate. 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, 203 g of methoxybenzenesulfonic acid obtained in Synthesis Example 1 was dissolved in 500 g of normal butanol in advance, and the ferric hydroxide dispersion prepared by the above method was added to the solution. Was added.
After stirring at room temperature for 12 hours for reaction, the mixture was distilled to obtain a normal butanol solution of ferric methoxybenzene sulfonate having a concentration of 50%.

After adjusting the concentration of the above-mentioned ferric methoxybenzene sulfonate by adding n-butanol to a concentration of 0.5 mol / l, 3,4-ethylenedioxythiophene was added to the solution. 0.5 mol / l was added, and the mixture was thoroughly stirred, and the oxidative polymerization of 3,4-ethylenedioxythiophene was started using the above-mentioned ferric methoxybenzenesulfonic acid salt as an oxidizing agent, and immediately, 18 on a 3 cm x 5 cm ceramic plate
0 μl was dropped. 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 allowed to stand for 5 minutes with a load of 1.5 t to make the film thickness uniform, and the conductivity of polyethylene dioxythiophene, which was the polymer, was measured by a 4-probe method. It was measured with a vessel (MCP-T600 manufactured by Mitsubishi Chemical Corporation). The results are shown in Table 1 below.

Example 2 Instead of the methoxybenzenesulfonic acid obtained in Synthesis Example 1,
Chemical oxidative polymerization of 3,4-ethylenedioxythiophene was carried out in the same manner as in Example 1 except that 218 g of ethoxybenzenesulfonic acid obtained in Synthesis Example 2 was used, and the electrical conductivity of the obtained polyethylenedioxythiophene was measured. did.
The results are shown in Table 1 below.

Example 3 Instead of the methoxybenzenesulfonic acid obtained in Synthesis Example 1,
257 g of methoxynaphthalenesulfonic acid obtained in Synthesis Example 3
The chemical oxidative polymerization of 3,4-ethylenedioxythiophene was performed in the same manner as in Example 1 except that was used, and the electrical conductivity of the obtained polyethylenedioxythiophene was measured. The results are shown in Table 1 below.

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

Comparative Example 2 Instead of the methoxybenzenesulfonic acid obtained in Synthesis Example 1,
Chemical oxidative polymerization of 3,4-ethylenedioxythiophene was performed in the same manner as in Example 1 except that 352 g of branched dodecylbenzenesulfonic acid was used, and the electrical conductivity of the obtained polyethylenedioxythiophene was measured. The results are shown in Table 1 below.

Comparative Example 3 Instead of the methoxybenzenesulfonic acid obtained in Synthesis Example 1,
Chemical oxidative polymerization of 3,4-ethylenedioxythiophene was performed in the same manner as in Example 1 except that 225 g of naphthalenesulfonic acid was used, and the electrical conductivity of the obtained polyethylenedioxythiophene was measured. The results are shown in Table 1 below.
Shown in.

The electrical conductivity of the polyethylenedioxythiophenes obtained in Examples 1 to 3 and Comparative Examples 1 to 3 is shown in Table 1 together with the dopant.

[0035]

[Table 1]

As shown in Table 1, the polyethylenedioxythiophenes of Examples 1 to 3 were higher in electrical conductivity and excellent in conductivity than the polyethylenedioxythiophenes of Comparative Examples 1 to 3.

That is, polyethylenedioxythiophene of Example 1 using methoxybenzenesulfonic acid as a dopant, polyethylenedioxythiophene of Example 2 using ethoxybenzenesulfonic acid as a dopant, and Example 3 using methoxynaphthalenesulfonic acid as a dopant. The polyethylene dioxythiophene is a polyethylene dioxythiophene of Comparative Example 1 having p-toluenesulfonic acid as a dopant, and the polyethylenedioxythiophene and naphthalenesulfonic acid of Comparative Example 2 having a branched dodecylbenzenesulfonic acid as a dopant are dopants. From the polyethylene dioxythiophene of Comparative Example 3
It had high conductivity and excellent conductivity.

Next, the above Examples 1 to 3 and Comparative Example 1
With respect to polyethylenedioxythiophene of Nos. 3 to 3, 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 3 and Comparative Examples 1 to 3 above, after measuring the electric conductivity as described above, each sheet was stored in a constant temperature bath 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 to 3 are 2% less than the polyethylenedioxythiophenes of Comparative Examples 1 to 3.
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, polyethylenedioxythiophene of Example 1 using methoxybenzenesulfonic acid as a dopant, polyethylenedioxythiophene of Example 2 using ethoxybenzenesulfonic acid as a dopant, and Example 3 using methoxynaphthalenesulfonic acid as a dopant. The polyethylene dioxythiophene is a polyethylene dioxythiophene of Comparative Example 1 having p-toluenesulfonic acid as a dopant, and the polyethylenedioxythiophene and naphthalenesulfonic acid of Comparative Example 2 having a branched dodecylbenzenesulfonic acid as a dopant are dopants. As compared with the polyethylene dioxythiophene of Comparative Example 3, the electric conductivity was less decreased by high temperature storage and the heat resistance was excellent.

Next, examples in which a conductive polymer was synthesized by electrolytic oxidation polymerization and evaluated were shown as Examples 4 to 5 and Comparative Examples 4 to 6.

Example 4 First, a ceramic plate coated with a conductive polymer used as an anode for electrolytic oxidative 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 obtained ceramic plate (that is, a ceramic plate coated with polyethylenedioxythiophene) is used as an anode,
Using stainless steel (SUS304) as a cathode, electrolytic oxidation polymerization of pyrrole was performed as shown below.

The sodium salt of methoxybenzenesulfonic acid obtained in Synthesis Example 1 was previously added to a concentration of 0.04 mo.
Pyrrole was added to a solution whose concentration was adjusted to 1 / l with pure water so that the concentration was 0.04 mol / l.
Then, a polypyrrole having methoxybenzenesulfonic acid incorporated as a dopant was synthesized by electrolytically oxidatively polymerizing a constant current of 1 mA / cm for 70 minutes using the above electrode. The obtained polypyrrole was thoroughly washed with ethanol, dried at 150 ° C. for 1 hour, and then a 4-probe conductivity measuring device (MCP manufactured by Mitsubishi Chemical Corporation).
-T600) was used to measure the surface resistance. The results are shown in Table 3 below.

Example 5 Pyrrole was prepared in the same manner as in Example 4 except that the sodium salt of methoxynaphthalenesulfonic acid obtained in Synthesis Example 3 was used in place of the sodium salt of methoxybenzenesulfonic acid obtained in Synthesis Example 1. The surface resistance of the polypyrrole obtained by electrolytic oxidative polymerization was measured. The results are shown in Table 3 below.

Comparative Example 4 Pyrrole was electrolytically oxidatively polymerized in the same manner as in Example 4 except that the sodium salt of p-toluenesulfonic acid was used instead of the sodium salt of methoxybenzenesulfonic acid obtained in Synthesis Example 1. The surface resistance of the obtained polypyrrole was measured.
The results are shown in Table 3 below.

Comparative Example 5 Pyrrole was electrolytically oxidized and polymerized in the same manner as in Example 4 except that the sodium salt of branched dodecylbenzenesulfonic acid was used in place of the sodium salt of methoxybenzenesulfonic acid obtained in Synthesis Example 1. 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 the sodium salt of butylnaphthalenesulfonic acid was used in place of the sodium salt of methoxybenzenesulfonic acid obtained in Synthesis Example 1. The surface resistance of the obtained polypyrrole was measured. The results are shown in Table 3 below.

The results of measuring the surface resistance of the polypyrroles obtained in Examples 4 to 5 and Comparative Examples 4 to 6 are shown in Table 3 together with their dopants.

[0052]

[Table 3]

As shown in Table 3, it was apparent that the polypyrroles of Examples 4 to 5 had a smaller surface resistance and a higher electric conductivity than the polypyrroles of Comparative Examples 4 to 6. That is, the polypyrrole of Example 4 having methoxybenzenesulfonic acid as a dopant and the polypyrrole of Example 5 having methoxynaphthalenesulfonic acid as a dopant are the polypyrrole of Comparative Example 4 having p-toluenesulfonic acid as a dopant and a branched dodecylbenzene. Compared to the polypyrrole of Comparative Example 5 using sulfonic acid as a dopant and the polypyrrole of Comparative Example 6 using butylnaphthalene sulfonic acid as a dopant, the surface resistance was small and the conductivity was excellent. Particularly, the polypyrroles of Examples 4 to 5 have a comparative example 6 in which butylnaphthalenesulfonic acid is used as a dopant.
The surface resistance was smaller and the conductivity was superior to that of the polypyrrole.

Next, the above Examples 4 to 5 and Comparative Example 4
After measuring the surface resistance of the polypyrroles Nos. 6 to 6 as described above, a high temperature storage test was conducted in the same manner as the polyethylenedioxythiophene of Example 1 to examine the increase in the surface resistance due to the high temperature storage. The results are shown in Table 4.

[0055]

[Table 4]

As shown in Table 4, the polypyrroles of Examples 4 to 5 are 24 compared to the polypyrroles of Comparative Examples 4 to 5.
After storage for 48 hours, surface resistance is small,
The heat resistance was excellent.

That is, the polypyrrole of Comparative Example 4 containing p-toluenesulfonic acid as a dopant and the polypyrrole of Comparative Example 5 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 4 having methoxybenzenesulfonic acid as a dopant and the polypyrrole of Example 5 having methoxynaphthalenesulfonic acid as a dopant, but when stored at high temperature, As compared with the polypyrrole of Example 4 and the polypyrrole of Example 5, the surface resistance was greatly increased and the heat resistance was inferior. Further, the polypyrrole of Comparative Example 6 using butylnaphthalene sulfonic 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 4 Compared to the polypyrrole and the polypyrrole of Example 5, Example 4
Unlike the polypyrrole of Example 1 and the polypyrrole of Example 5, it was not possible to have both excellent conductivity and excellent heat resistance.

Next, solid electrolytic capacitors using a conductive polymer as a solid electrolyte are shown as Examples 6 to 8 and Comparative Examples 7 to 9.

Examples 6 to 8 and Comparative Examples 7 to 9 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 salts of sulfonic acid obtained in the processes of Examples 1 to 3 and Comparative Examples 1 to 3 were respectively added. The solid electrolyte layer made of polyethylenedioxythiophene was formed by separately impregnating and heating at 60 ° C. for 2 hours. 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 6 to 8 and Comparative Examples 7 to 9 thus produced were measured. The results are shown in Table 5 together with the type of dopant.

[0061]

[Table 5]

As shown in Table 5, the solid electrolytic capacitors of Examples 6 to 8 had a smaller ESR value than the solid electrolytic capacitors of Comparative Examples 7 to 9.

That is, a solid electrolytic capacitor of Example 6 using a conductive polymer having methoxybenzenesulfonic acid as a dopant and a conductive polymer having ethoxybenzenesulfonic acid as a dopant as a solid electrolyte. The solid electrolytic capacitor of Example 7 and the solid electrolytic capacitor of Example 8 using a conductive polymer having methoxynaphthalenesulfonic acid as a dopant as a solid electrolyte are the same as the conductive polymer having p-toluenesulfonic acid as a dopant. Used as a solid electrolytic capacitor of Comparative Example 7, a conductive polymer having a branched dodecylbenzenesulfonic acid as a dopant, a conductive polymer as a solid electrolyte, and a conductive polymer having naphthalenesulfonic acid as a dopant. Of Comparative Example 9 using as a solid electrolyte Compared to the body electrolytic capacitor, ESR
And the reliability of the characteristics was high under high temperature and high humidity conditions.

[0064]

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 Kohei Kitamura             Takeka, 1-3-4, Funamachi, Taisho-ku, Osaka             Within the corporation F-term (reference) 4J032 BA03 BA04 BA13 BA14 BB01                       BB03 BB04 BB05 BC02 BC21                       BC32 CG01                 4J043 PA02 QB02 XA21 XA34 XB13                       YB05 YB38 ZA44 ZB47 ZB49

Claims (4)

[Claims] 1. At least one selected from alkoxybenzene sulfonic acid, alkoxynaphthalene sulfonic acid, and alkoxy tetralin sulfonic acid containing at least one alkoxyl group having 1 to 18 carbon atoms and containing at least one sulfone group. A conductive polymer comprising one or more sulfonic acids 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. The conductive polymer according to claim 1, wherein the alkoxyl group has 1 to 5 carbon atoms. 4. A solid electrolytic capacitor using the conductive polymer according to claim 1 as a solid electrolyte.