JP2000178454A - Electroconductive polymeric material and solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject material suitable as a cathodic electroconductive material for solid electrolytic capacitors having favorable impedance characteristics up to a high-frequency range and high heat resistance by making the material include a specific polymeric substance and a specific compound. SOLUTION: This electroconductive polymeric material is obtained by including (A) a polymeric substance having molecular structure with electron conjugated system and (B) a 3-sulfonylbenzenesulfonic acid derivative compound of formula I (X is H, a 1-20C alkyl, alkoxy or aryl) wherein the component A is pref. e.g. a conjugated polymeric compound having at least one kind of repeating unit selected from among those of formula II to formula IV (R1 to R8 are each H, an alkyl or alkoxy) (e.g. pyrrole), and the component B is e.g. 3-methylsulfonylbenzenesulfonic acid, 3-ethylsulfonylbenzenesulfonic acid, 3-n- propylsulfonylbenzenesulfonic acid, 3-phenylsulfonylbenzenesulfonic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive polymer material and a solid electrolytic capacitor using the same.
More specifically, the present invention relates to a conductive material suitable for manufacturing a solid electrolytic capacitor having excellent frequency characteristics and heat resistance, and a solid electrolytic capacitor using the same as a cathode conductive material.

[0002]

BACKGROUND OF THE INVENTION In recent years, with the development of electronics, new electronic materials have been developed. In particular, remarkable technological progress has been made in the field of functional organic materials.Electron-accepting compounds are used as dopants in electron conjugated polymer materials such as polyacetylene, polyparaphenylene, polypyrrole, and polyaniline, even in the case of conductive materials only. A doped conductive polymer material has been developed, and in some cases, for example, it has already been put to practical use as a capacitor electrode material, a battery electrode material, an antistatic material and the like.

Meanwhile, a solid electrolytic capacitor has a metal such as tantalum or aluminum as an anode, and an oxide film such as tantalum or aluminum is formed as a dielectric on the surface of the anode, while manganese dioxide or tetracyanoquinodimethane (metal oxide) is formed. (TCNQ) complex salt as a cathode has been developed. However, when manganese dioxide is used as a cathode, the solid electrolytic capacitor has a high impedance in a high frequency region due to its low conductivity,
It has been pointed out that when a CNQ complex salt is used as a cathode, the solid electrolytic capacitor has poor heat resistance because it is easily thermally decomposed.

[0004] Therefore, the use of a conductive polymer material such as polypyrrole or polyaniline described above as a cathode has been studied. It has been found that these conductive high-molecular substances have higher conductivity than manganese dioxide and have better heat resistance than TCNQ complex salts.

Focusing on this characteristic, many improvements have been proposed for solid electrolytic capacitors using these conductive polymer materials as cathodes. For example, JP
JP-A-37114 discloses a solid electrolytic capacitor using a five-membered heterocyclic compound polymer doped with a dopant as a solid electrolyte.
Japanese Patent Application Publication No. JP-A-2005-115139 discloses a solid electrolytic capacitor using polyaniline as a solid electrolyte.

However, since higher performance and higher reliability have been demanded for elements for information electronic equipment, solid electrolytic capacitors have good impedance characteristics up to a high frequency range, and have high heat resistance. There is a demand for the development of materials that are excellent in quality.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a conductive polymer material having good impedance characteristics up to a high frequency range and excellent heat resistance and suitable as a cathode conductive material for a solid electrolytic capacitor. The purpose is to provide a solid electrolytic capacitor used.

[0008]

That is, the present invention provides a polymer substance having an electron conjugated molecular structure containing a 3-sulfonylbenzenesulfonic acid derivative compound represented by the following general formula (1). And a conductive polymer material characterized by the following.

[0009]

Embedded image Here, X is any one of a hydrogen atom and a group selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group, and an aryl group.

In the present invention, it is particularly preferable that the polymer substance is a conjugated polymer compound having at least one type of repeating unit represented by the following general formula (2), (3) or (4). .

[0011]

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[0012]

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[0013]

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The above equations (2), (3) and (4)
Wherein R _{1 to} R ₈ may be the same or different, and each is a hydrogen atom, or a group selected from the group consisting of an alkyl group having 1 to 20 carbon atoms and an alkoxy group,
* Indicates the bonding position of the repeating unit.

[0015] The present invention also relates to the use of the above conductive polymer material as a cathode conductive material in a solid electrolytic capacitor.

[Detailed Description of the Invention] Next, a conductive polymer material according to the present invention and a solid electrolytic capacitor using the same as a cathode conductive material will be specifically described.

The conductive polymer material according to the present invention contains a 3-sulfonylbenzenesulfonic acid derivative compound represented by the following general formula (1) in a polymer substance having an electron conjugated molecular structure. .

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Here, X is a hydrogen atom or a group selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group, and an aryl group. The above-mentioned alkyl group, alkoxy group, and aryl group may be linear, cyclic, or branched. Specific examples of the alkyl group, alkoxy group, and aryl group include methyl, ethyl, propyl, butyl, hexyl, 2-ethylhexyl, methoxy, ethoxy, propoxy, butoxy, cyclohexyl, phenyl, phenoxy and the like.

In the general formula (1), specific compounds having these groups include 3-methylsulfonylbenzenesulfonic acid, 3-ethylsulfonylbenzenesulfonic acid, 3-n-propylsulfonylbenzenesulfonic acid, -N-butylsulfonylbenzenesulfonic acid,
3- (2-ethylhexyl) sulfonylbenzenesulfonic acid, 3-methoxysulfonylbenzenesulfonic acid, 3
And 3-sulfonylbenzenesulfonic acids such as -ethoxysulfonylbenzenesulfonic acid and 3-phenylsulfonylbenzenesulfonic acid.

The polymer having an electron conjugated molecular structure constituting the conductive polymer according to the present invention includes:
For example, a pyrrole compound represented by the following general formula (2):
A conjugated polymer compound composed of at least one of a thiophene-based compound represented by (3) and an aniline-based compound represented by (4) as a repeating unit can be given.

[0021]

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[0022]

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[0023]

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In the above formula, R _{1 to} R ₈ may be the same or different and are a hydrogen atom or a linear, cyclic, or branched alkyl group or alkoxy group having 1 to 20 carbon atoms. Specific examples of R _{1 to} R ₈ include hydrogen, a methyl group,
Examples include an ethyl group, a propyl group, a butyl group, an octyl group, a methoxy group, and an ethoxy group. * Indicates the bonding position of the repeating unit.

In particular, it is preferable to use polypyrrole, polythiophene, or polyaniline consisting of only one kind of the repeating unit represented by the general formula (2), (3) or (4).

The polymer compound containing the above-mentioned repeating unit is obtained by oxidatively polymerizing a monomer which can constitute at least one of the formulas (2), (3) and (4) as a repeating unit. Can be manufactured.

Specific examples of the monomer represented by the above general formula (2), (3) or (4) include pyrrole,
Thiophene, 3-methylthiophene, 3-octylthiophene, 3-methoxythiophene, aniline, bithiophene, terthiophene, trans-bithienylethylene, tr
ans-bithienyl-1,4-butadiene, bipyrrole, terpyrrole, 2,5-bipyroylthiophene, p, p'-bipyrroylbenzene, 2,5'-biphenylterpyrrole, 2,5'-bithienylbi Pyrrole and the like can be mentioned.

When producing an electron conjugated polymer from a polymerization system containing the above-mentioned general formula (2), (3) or (4), 3-sulfonylbenzenesulfonic acid represented by the general formula (1) The conductive polymer material according to the present invention can be obtained by causing the derivative compound to coexist in the polymerization system and oxidative polymerization. The oxidative polymerization method can be performed by any of an electrochemical oxidative polymerization method and a chemical oxidative polymerization method.

In order to carry out the electrochemical oxidation polymerization, that is, the polymerization by the electrolytic polymerization method, the 3-sulfonylbenzenesulfonic acid derivative compound represented by the general formula (1) or a salt thereof is combined with the above-mentioned polymer constituting the polymer substance. Dissolve the monomer in the solvent,
A conductive polymer material can be obtained by promoting the polymerization of the monomer under a constant potential or constant current condition. The solvent used in the reaction may be any solvent that dissolves the 3-sulfonylbenzenesulfonic acid derivative compound or a salt thereof and that dissolves a monomer that can constitute a repeating unit.
For example, water, dimethylformamide, acetonitrile, propylene carbonate and the like can be mentioned. The electrolytic polymerization can be performed in a temperature range of -100 to 150C, preferably 0 to 50C, and may be any of a constant current electrolysis method and a constant potential electrolysis method. Further, the electrolytic polymerization is desirably performed in an atmosphere of an inert gas such as nitrogen or argon.

In order to carry out the polymerization by the chemical oxidative polymerization method, a transition metal complex having a conjugate base of a 3-sulfonylbenzenesulfonic acid derivative compound as a ligand is used as an oxidizing agent.
This is performed by bringing a monomer having a repeating unit forming a polymer compound having an electron conjugated molecular structure into contact with a solvent in a solvent. Examples of the central metal constituting the transition metal complex include iron, cobalt, ruthenium and the like, and among them, trivalent iron in a highly oxidized state is particularly preferable. The transition metal complex is usually used in an amount of 1 to 10 mol per 1 mol of the monomer. The solvent used in the reaction may be any solvent that dissolves the above-mentioned transition metal complex and monomer, and examples thereof include water, dimethylformamide, acetonitrile, tetrahydrofuran, and propylene carbonate. The polymerization temperature is 0
50 ° C. is preferable, and the reaction time is preferably 1 to 48 hours. The polymerization is desirably performed in an atmosphere of an inert gas such as nitrogen or argon.

This conductive polymer material can be effectively used in the fields of various electrode materials and antistatic agents.

Next, the conductive polymer material according to the present invention is
The use of the solid electrolytic capacitor as a cathode conductive material will be described. A solid electrolytic capacitor generally has a basic structure in which an anode metal and a cathode conductive material are joined via a dielectric layer, and an electrode lead is attached to each of the anode metal and the cathode conductive material.

Examples of the metal constituting the anode metal include aluminum and tantalum, which are usually used in the form of a foil. Further, the surface may be etched. On the other hand, the cathode conductive material is generally used by processing an inorganic or organic conductive material into a film. Further, a metal cathode may be provided on the surface. Further, a structure in which a graphite layer is provided between the cathode conductive material and the metal cathode to improve the contact between the cathode conductive material and the metal cathode may be employed. The dielectric layer is generally an oxide layer of an anode metal, and can be formed by oxidizing the surface of the anode metal. Further, it can also be formed by applying a coating solution containing an oxide of an anode metal.

The solid electrolytic capacitor according to the present invention contains the above-described conductive material as a cathode conductive material, and a commonly used material can be directly used as an anode metal. The shape of the solid electrolytic capacitor on which the cathode and the anode are arranged may be any shape such as a cylindrical shape and a dip shape.

[0035]

EXAMPLES Next, the present invention will be described through examples and comparative examples, but the present invention is not limited to these examples.

(Example 1) 2.37 g of 3-methylsulfonylbenzenesulfonic acid and 0.67 g of pyrrole were added to pure water 1
The solution was dissolved in 00 ml to prepare an electropolymerization reaction solution. After nitrogen gas was bubbled through the reaction solution for about 30 minutes to replace with nitrogen, two pieces of 2 cm square stainless steel 304 were added to the reaction solution.
It was immersed at an interval of cm to obtain a working electrode and a counter electrode.

Using two dipped stainless steel electrodes, a constant current (2.5 mA / cm) was passed for 20 minutes to carry out electrolytic polymerization. The polypyrrole film formed on the electrode is washed with pure water and acetone, then peeled off from the electrode,
Dry at room temperature for 12 hours. As a result of measuring the electric conductivity of the obtained film by a four probe method, an electric conductivity of 126 (S / cm) was obtained.

Example 2 A polypyrrole film was prepared by repeating the same operation as in Example 1 except that 3-methoxysulfonylbenzenesulfonic acid was used instead of 3-methylsulfonylbenzenesulfonic acid. Created. Table 1 shows the values of the electric conductivity measured by the four probe method.
It was shown to.

Comparative Example 1 A polypyrrole film was prepared in the same manner as in Example 1 except that p-toluenesulfonic acid was used instead of 3-methylsulfonylbenzenesulfonic acid. Table 1 also shows the measurement results of the electric conductivity measured by the four probe method.

[0040]

[Table 1]

Example 3 The film obtained in Example 1 was heat-treated at 150 ° C. in air for 8 hours. The electric conductivity after the heat treatment was 50 (S / cm) (four-point probe method). Based on the electrical conductivity before the heat treatment, the conductivity retention was 40%.

Example 4 Using the polypyrrole film obtained in Example 2, the same operation as in Example 3 was conducted, and the conductivity retention was examined. The results are shown in Table 2.

Comparative Example 2 Using the polypyrrole film obtained in Comparative Example 1, the same operation as in Example 3 was repeated. The conductivity retention is also shown in Table 2.

[0044]

[Table 2]

[0045]

According to the present invention, since a 3-sulfonylbenzenesulfonic acid derivative compound is contained in an electron conjugated polymer substance, a conductive polymer material having high conductivity and excellent heat resistance can be obtained. I was able to. In addition, when this conductive polymer material is used as a cathode conductive material of a solid electrolytic capacitor, it is possible to obtain a solid electrolytic capacitor having a low impedance at a resonance frequency, good high-frequency characteristics, and little characteristic deterioration at high temperatures. did it.

Claims (6)

[Claims] 1. A conductive polymer comprising a 3-sulfonylbenzenesulfonic acid derivative compound represented by the following general formula (1) in a polymer substance having an electron conjugated molecular structure. material. Embedded image Here, X is any one of a hydrogen atom and a group selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group, and an aryl group. 2. In the general formula (1), X is any one of a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group and a phenyl group. The conductive polymer material according to claim 1, wherein: 3. The compound represented by the general formula (1)
3-methylsulfonylbenzenesulfonic acid, 3-ethylsulfonylbenzenesulfonic acid, 3-n-propylsulfonylbenzenesulfonic acid, 3-n-butylsulfonylbenzenesulfonic acid, 3-methoxysulfonylbenzenesulfonic acid, 3-ethoxysulfonylbenzenesulfone 2. The conductive polymer material according to claim 1, wherein the conductive polymer material is an acid, 3-phenylsulfonylbenzenesulfonic acid. 4. The polymer material according to the following general formula (2):
The conductive polymer material according to claim 1, comprising a conjugated polymer compound having at least one type of repeating unit represented by (3) or (4). Embedded image Embedded image Embedded image In the above formula, R _{1 to} R ₈ may be the same or different from each other, and are any of a hydrogen atom, and a group selected from the group consisting of an alkyl group having 1 to 20 carbon atoms and an alkoxy group, * Indicates the bonding position of the repeating unit. 5. A solid electrolytic capacitor comprising the conductive polymer material according to claim 1 as a cathode conductive material. 6. A 3-sulfonylbenzenesulfonic acid derivative compound represented by the following general formula (1): Here, X is a hydrogen atom or a group selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, an alkoxy group, and an aryl group, and is represented by the following general formulas (2) and (3) Or a conductive polymer material contained in a polymer material comprising a conjugated polymer compound having at least one type of repeating unit represented by (4), as a cathode conductive material. Solid electrolytic capacitor. Embedded image Embedded image Embedded image In the above formula, R _{1 to} R ₈ may be the same or different from each other, and are any of a hydrogen atom, and a group selected from the group consisting of an alkyl group having 1 to 20 carbon atoms and an alkoxy group, * Indicates the bonding position of the repeating unit.