JP3464733B2 - Solid electrolytic capacitor and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention mainly has a structural unit having an acidic group and an electron donating group in the same aromatic ring represented by the general formula (1), and has a weight average molecular weight of 3000 or more and an acidic group with respect to an aromatic ring. The content of the group is 70% or more and the conductivity is 0.
The present invention relates to a solid electrolytic capacitor using a soluble aniline-based conductive polymer of 01 S / cm or more as a solid electrolyte and a method for manufacturing the same.

[0002]

2. Description of the Related Art A solid electrolytic capacitor is a capacitor in which an insulating porous molded body is formed on the surface of a metal foil of tantalum or aluminum or a metal sintered body, and the insulating film is used as a dielectric. With the recent progress in science and technology, miniaturization of electronic devices and higher frequencies of circuits are required, and capacitors are also required to have lower impedance, higher reliability, and lower cost. However, the method of using manganese dioxide, which is mainly used at present, as an electrolyte has a problem that the impedance is high in a high frequency region because the conductivity is not sufficient. Also TC
The method of using the NQ complex as an electrolyte has a problem that the TCNQ complex is easily decomposed by heat and thus has poor heat resistance.

As a means for solving these problems, a method of using a conductive polymer such as polypyrrole or polyaniline has been proposed in recent years (JP-A-63-173313, JP-A-1-253226, JP Kaihei 3-35516, JP 5-3138, JP 6-29159, JP 7-860
No. 93 bulletin).

[0004]

However, in the case of producing a solid electrolytic capacitor using polypyrrole as a solid electrolyte, polypyrrole is not dissolved in a solvent, so that a conductive precoat layer is formed on the metal oxide film coating, and then polypyrrole is formed. However, there is a problem in that the process is complicated because it is electrolytically polymerized. Further, in the case of producing a solid electrolytic capacitor using polyaniline as a solid electrolyte, the solubility of polyaniline is low, so that impregnation into the porous molded body is insufficient, and there is a problem that the characteristics do not reach the target performance. .
Further, these conductive polymers have a problem that it is necessary to take a sufficient doping time in order to exhibit high conductivity, and the manufacturing time becomes long.

[0005]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the inventors have found that an acidic group and an electron donating group are formed in the same aromatic ring represented by the general formula (1) as a solid electrolyte. Mainly having a structural unit having, a weight average molecular weight of 3000 or more, and the content of the acidic group to the aromatic ring 70% or more, and the conductivity is 0.01S / cm or more using a soluble aniline-based conductive polymer high frequency characteristics and The inventors have found that a solid electrolytic capacitor having excellent heat resistance can be obtained, and completed the present invention. Further, the soluble aniline-based conductive polymer of the present invention has high solubility in water, an organic solvent and a water-containing organic solvent, and a doping process after film formation is not required, so that the method for manufacturing a capacitor is simplified.

A detailed description will be given below. The soluble aniline-based conductive polymer used in the present invention mainly has a structural unit having an acidic group and an electron donating group in the same aromatic ring represented by the general formula (1).

[Chemical 4] (In the formula, R _1, R _2, R _3, R _4, are electron withdrawing groups, acidic groups, hydrogen, linear or branched alkyl groups having 1 to 4 carbon atoms, alkenyl groups, alkoxy groups, hydroxyl groups, nitro groups. A group and a halogen, and at least two of the substituents each represent an acidic group or an electron withdrawing group.) The structure of the polymer mainly having the structural unit represented by the general formula (1) is It is said to have a phenylenediamine structure (reduced type) and a quinodiimine structure (oxidized type) represented by the general formula (2).

[0007]

[Chemical 5] (In the formula, R _{5 to} R ₂₀ are a group consisting of an electron withdrawing group, an acidic group, hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, an alkenyl group, an alkoxy group, a hydroxyl group, a nitro group, and a halogen. At least two of the four substituents on each aromatic ring each represent an acidic group or an electron-withdrawing group.) This phenylenediamine structure (reduced type) and quinodiimine structure (oxidized type) are It is possible to reversibly convert at an arbitrary ratio. Ratio of phenylenediamine structure to quinodiimine structure: x is 0.2 <x
A range of <0.8 is preferable from the viewpoint of conductivity and solubility, and 0.
3 <x <0.7 is more preferable.

The soluble aniline-based conductive polymer of the present invention is a structural unit other than that represented by the general formula (1) or the general formula (2) as long as it does not affect the solubility, conductivity and properties. It may contain at least one structural unit of a substituted or unsubstituted aniline, thiophene, pyrrole, phenylene, vinylene, another divalent unsaturated group and a divalent saturated group. The soluble aniline-based conductive polymer of the present invention has a repeating unit of the general formula (1) or (2), that is, an acidic group content of 70 relative to an aromatic ring.
% Or more is used, preferably 80% or more, more preferably 90% or more. Here, it is not preferable that the content of the acidic group in the aromatic ring is 70% or less because the solubility in water is insufficient. Further, the higher the content of the acidic group in the aromatic ring, the higher the solubility, and the one in which the content of the acidic group in the aromatic ring is 100% has the highest solubility and is suitable for capacitor production. The weight average molecular weight is 30 in terms of GPC polyethylene glycol.
A polymer having a weight average molecular weight of 00 or more is preferably excellent in conductivity, film-forming property and film strength, a polymer having a weight average molecular weight of 5,000 or more and 500,000 or less is more preferable, and a polymer having a weight average molecular weight of 7,000 or more and 300,000 or less is further preferable.
Where the weight average molecular weight of 3000 or less, the solubility is excellent but the film forming property and the conductivity are insufficient, and the one having a weight average molecular weight of 500,000 or more is excellent in the conductivity but the solubility and the porous molding. Impregnation into the body is insufficient. In a solid electrolytic capacitor, the higher the conductivity, the better the performance such as frequency characteristics. Therefore, a soluble conductive polymer having a conductivity of 0.01 S / cm or more, preferably 0.05 S / cm or more is used.

The soluble aniline type conductive polymer of the present invention comprises at least one aminobenzenesulfonic acid derivative and / or aminobenzoic acid derivative having an acidic group and an electron donating group in the same aromatic ring in the presence of a basic compound. Those obtained by oxidative polymerization are preferably used. As the raw material monomer, the general formula (3) is used.

[Chemical 6] (In the formula, R _21, R ₂₂ , R ₂₃ , R ₂₄ , and R ₂₅ are electron withdrawing groups, acidic groups, hydrogen, linear or branched electron withdrawing groups having 1 to 4 carbon atoms, acidic groups, alkyl groups, It is selected from the group consisting of an alkenyl group, an alkoxy group, a hydroxyl group, a nitro group, and a halogen, at least two of which represent an acidic group and an electron-withdrawing group, and the acidic group is preferably a sulfone group or a carboxylic acid group. Acid group-substituted aniline, its alkali metal salt, ammonium salt, and substituted ammonium salt. The compound of the general formula (1), in which the acidic group and the electron-withdrawing group are bonded to the o-position or the m-position with respect to the amino group, is superior in the performance such as conductivity and solubility of the obtained polymer. .

The most typical acid group-substituted aniline is an aminobenzenesulfonic acid derivative or an aminobenzoic acid derivative. The aminobenzenesulfonic acid derivative tends to have higher conductivity than the aminobenzoic acid derivative, while the aminobenzoic acid derivative tends to have higher solubility than the aminobenzenesulfonic acid derivative. As these derivatives, a copolymer in an arbitrary ratio can be used according to the purpose.

The most typical aminobenzene sulfonic acid is specifically o-, m-, p-aminobenzene sulfonic acid, aniline-2,6-disulfonic acid, aniline-2,5-disulfonic acid, Aniline-3,5-disulfonic acid, aniline-2,4-disulfonic acid and aniline-3,4-disulfonic acid are preferably used.

Other aminobenzenesulfonic acids include methylaminobenzenesulfonic acid, ethylaminobenzenesulfonic acid, n-propylaminobenzenesulfonic acid, iso-propylaminobenzenesulfonic acid and n.
-Butylaminobenzenesulfonic acid, sec-butylaminobenzenesulfonic acid, t-butylaminobenzenesulfonic acid, and other alkyl group-substituted aminobenzenesulfonic acids, methoxyaminobenzenesulfonic acid, ethoxyaminobenzenesulfonic acid, n-propoxyaminobenzenesulfone Acid, iso-propoxyaminobenzenesulfonic acid, n-butoxyaminobenzenesulfonic acid, se
Alkoxy group-substituted aminobenzene sulfonic acids such as c-butoxyaminobenzene sulfonic acid and t-butoxyaminobenzene sulfonic acid, hydroxy group-substituted aminobenzene sulfonic acids, nitro group-substituted aminobenzene sulfonic acids, fluoroaminobenzene sulfonic acid, chloroaminobenzene Examples thereof include halogen group-substituted aminobenzenesulfonic acids such as sulfonic acid and bromoaminobenzenesulfonic acid. Among these, alkyl group-substituted aminobenzene sulfonic acids, alkoxy group-substituted aminobenzene sulfonic acids or hydroxy group-substituted aminobenzene sulfonic acids are most preferable in practical use.

The most typical aminobenzoic acid derivatives are o-, m-, p-aminobenzoic acid and aniline-
2,6-dicarboxylic acid, aniline-2,5-dicarboxylic acid, aniline-3,5-dicarboxylic acid, aniline-2,
4-dicarboxylic acid and aniline-3,4-dicarboxylic acid are preferably used.

Other aminobenzoic acid derivatives include:
Alkyl group-substituted amino such as methylaminobenzoic acid, ethylaminobenzoic acid, n-propylaminobenzoic acid, iso-propylaminobenzoic acid, n-butylaminobenzoic acid, sec-butylaminobenzoic acid, t-butylaminobenzoic acid Benzoic acids, methoxyaminobenzoic acid, ethoxyaminobenzoic acid, n-pyropoxyaminobenzoic acid,
Alkyl group-substituted aminobenzoic acids such as iso-pyropoxyaminobenzoic acid, n-butoxyaminobenzoic acid, sec-butoxyaminobenzoic acid, t-butoxyaminobenzoic acid, hydroxy group-substituted aminobenzoic acids, fluoroaminobenzoic acid, chloroaminobenzoic acid Examples thereof include acids and halogen group-substituted aminobenzoic acids such as bromoaminobenzoic acid. Of these, alkyl group-substituted aminobenzoic acids, alkoxy group-substituted aminobenzoic acids, and hydroxy group-substituted aminobenzoic acids are the most practically preferred. In addition, these aminobenzenesulfonic acid and aminobenzoic acid derivatives may be used alone respectively, or isomers may be mixed at an arbitrary ratio.

More specifically, specific examples of the acidic group-substituted aniline represented by the general formula (1) include alkyl group-substituted aminobenzenesulfonic acid alkyl group-substituted aminobenzoic acid alkoxy group-substituted aminobenzenesulfonic acid alkoxy group-substituted aminobenzoic acid hydroxy group. Substituted aminobenzenesulfonic acid Hydroxy group Substituted aminobenzoic acid Fluoro group Substituted aminobenzenesulfonic acid Fluoro group Substituted aminobenzoic acid chloro group Substituted aminobenzene sulfonic acid chloro group Substituted aminobenzoic acid Bromo group Substituted aminobenzene sulfonic acid and bromo group Substituted aminobenzoic acid Examples thereof include acids and the like, and specific examples of the positions and combinations of these substituents are shown in Table 1.

[0016]

[Table 1] Here, A: one group selected from a sulfonic acid group or a carboxylic acid group, an alkali metal salt, an ammonium salt, and a substituted ammonium salt thereof, B: an electron withdrawing group, specifically, a methyl group, Alkyl group such as ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, t-butyl group, alkoxy group, hydroxy group, halogen group such as fluoro group, chloro group and bromine group. One group selected from H, hydrogen, methyl group, ethyl group, n-propyl group, is
o-propyl group, n-butyl group, sec-butyl group,
One group selected from an alkyl group such as t-butyl group, an alkoxy group, a hydroxy group, a nitro group, a fluoro group, a chloro group, and a halogen group such as a bromine group is shown.

Examples of alkali metals in these monomers include lithium, sodium and potassium.

Examples of the substituted ammonium include aliphatic ammonium, cyclic saturated ammonium, cyclic unsaturated ammonium and the like.

The basic compound used in the present invention may be any compound as long as it is a compound which forms a salt with the above-mentioned raw material monomer, but it may be a fatty amine, a cyclic saturated amine or a cyclic amine. Unsaturated amines and inorganic bases are preferably used.

The fatty amines are represented by the following formula (8)

[Chemical 7] (In the formula, each of R _{1 to} R ₃ is a group independently selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, CH ₂ OH and CH ₂ CH ₂ OH.). Compound,

Or the general formula (9)

[Chemical 8] (In the formula, each of R _{29 to} R ₃₂ is a group independently selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, CH ₂ OH and CH ₂ CH ₂ OH.). A side compound may be mentioned.

The cyclic saturated amines include piperidine,
Pyrrolidine, morpholine, piperazine, derivatives having these skeletons, and ammonium hydroxide compounds thereof are preferably used.

As the cyclic unsaturated amines, pyridine,
[alpha] -picoline, [beta] -picoline, [gamma] -picoline, quinone, isoquinoline, pyrroline, derivatives having these skeletons, and ammonium hydroxide compounds thereof are preferably used.

As the inorganic base, salts of hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide and aqueous ammonia are preferably used.

The concentration of these basic compounds is 0.1 mol
/ L or more, preferably 0.1 to 10.0 mol / l, more preferably 0.2 to 8.0 mol / l. At this time, when the amount is 0.1 mol / l or less, the yield of the obtained polymer tends to decrease, and when it is 10.0 mol / l or more, the conductivity tends to decrease. The basic compounds may be mixed and used in arbitrary proportions. Further, the compound (a) such as the above-mentioned acidic group-substituted aniline
The molar ratio of the acidic group (ha) and the basic compound (b) in the (ha) :( b) = 1: 100 to 100: 1, preferably 1: 0.25 to 1:20, and more preferably 1: 0.5
˜1: 15 can be used. Here, if the ratio of the basic compound is low, the reactivity decreases and the conductivity also decreases. On the contrary, when the ratio is high, the ratio of the acidic group and the basic compound in the obtained polymer to form a salt is high and the conductivity tends to be lowered.

The polymerization or copolymerization is carried out by oxidative polymerization with an oxidizing agent in a solution containing these basic compounds. As the solvent, water, methanol, ethanol, isopropanol, acetonitrile, methyl isobutyl ketone, methyl ethyl ketone, dimethylformamide, dimethylacetamide and the like are preferably used.

The standard electrode potential of the oxidant is 0.6 V.
The oxidizing agent is not particularly limited as long as it is the above-mentioned oxidizing agent, but peroxodisulfates such as peroxodisulfate, ammonium peroxodisulfate, sodium peroxodisulfate and potassium peroxodisulfate, hydrogen peroxide and the like are preferably used, and 1 mol of the monomer is used. On the other hand, it is used in an amount of 0.1 to 5 mol, preferably 0.5 to 5 mol. At this time, it is also effective to add a transition metal compound such as iron or copper as a catalyst.

The reaction temperature is preferably in the temperature range of -15 to 70 ° C, more preferably -5 to -5 ° C.
A range of 60 ° C applies. Here, if the temperature is -15 ° C or lower, or 70 ° C or higher, the conductivity tends to decrease.

The product synthesized by this method is usually x
Is obtained in the range of 0.2 to 0.8, and x is small when oxidized with an oxidizing agent such as benzoyl peroxide, ammonium peroxodisulfate and hydrogen peroxide,
When x is reduced with a reducing agent such as hydrazine, phenylhydrazine, sodium borohydride, and sodium hydride, a large x is obtained. A in the present invention is a group independently selected from the group consisting of hydrogen, alkali metal, ammonium and substituted ammonium, that is, these groups can be obtained in a mixed state rather than alone.

Specifically, when polymerized in the presence of sodium hydroxide, most of A in the isolated polymer is in the state of sodium, but most of A is treated when treated in an acid solution. It can be a hydrogen-substituted polymer. However, even if the acid substitution is sufficiently carried out, it is difficult to obtain the one completely replaced with hydrogen. Similarly, when polymerized in the presence of ammonia, most of A is ammonium, when polymerized in the presence of trimethylamine, most of A is trimethylammonium, and when polymerized in the presence of quinoline, most of A is quinolinium. can get. When basic compounds are mixed and used, A is obtained in a mixed state. Specifically, when polymerized in the presence of sodium hydroxide and ammonia, A in the isolated polymer is obtained in the presence of both sodium and ammonium. Also, when the obtained polymer is treated with a solution containing both sodium hydroxide and ammonia, A in the polymer is similarly obtained in the state where both sodium and ammonium are present.

In the capacitor manufacturing method of the present invention,
The film-forming metal is aluminum, tantalum, zirconium, magnesium, silicon or the like, and is used in the form of a rolled foil, a fine powder sintered body or the like.

A capacitor can be manufactured by impregnating the solution of the soluble aniline-based conductive polymer of the present invention on the oxide film of the coating forming metal and then drying. In the capacitor manufacturing method of the present invention, the solvent is not particularly limited as long as it is a solvent that dissolves the soluble aniline-based conductive polymer, but water, a water-containing organic solvent, and the like are preferable.
Specifically, alcohols such as methanol, ethanol and isopropyl alcohol, ethylene glycols such as ethylene glycol, ethylene glycol methyl ether, ethylene glycol ethyl ether and ethylene glycol butyl ether, propylene glycol, propylene glycol methyl ether and propylene glycol ethyl ether. , Propylene glycols such as propylene glycol butoxy ether, formamide,
Dimethylformamide, N-methylpyrrolidone, propylene carbonate, ethylene carbonate and the like are preferably used.

[0033]

[Effect] The soluble aniline-based conductive polymer of the present invention is
Highly soluble in water, organic solvents and hydrous organic solvents,
Moreover, since the doping process after film formation is not required, the manufacturing method of the capacitor is simplified. In addition, the capacitor using the soluble aniline-based conductive polymer of the present invention as a solid electrolyte provides a capacitor excellent in high frequency characteristics and heat resistance.

[0034]

EXAMPLES Examples will be described below. The IR spectrum is model-1600 manufactured by Perkin Elmer,
The UV-visible spectrum was measured using a UV-3100 apparatus manufactured by Shimadzu Corporation. For the measurement of the molecular weight distribution and the molecular weight, GPC measurement (polyethylene glycol conversion) was performed using a GPC column for aqueous solution. As the column, three types of columns for aqueous solution were connected and used. Also, for the eluent
A 0.2M phosphate buffer solution was used. A Mitsubishi Petrochemical 4-terminal method Loresta was used to measure the electrical conductivity, and a 2-terminal method Hiresta was used to measure the surface resistance. The characteristics of capacitors are
It was performed using a Hewlett Packard 4194A-impedance analyzer.

Example 1 100 mmol of 2-aminoanisole-4-sulfonic acid
Is dissolved in a 4 mol / liter aqueous ammonia solution with stirring at 25 ° C., and ammonium peroxodisulfate (100 mmol) is added.
Was added dropwise. After completion of the dropping, the mixture was further stirred at 25 ° C. for 12 hours, and the reaction product was separated by filtration, washed and dried to obtain 15 g of polymer powder. The conductivity of this product is 0.5 s / cm
Met. A solution prepared by dissolving 10 parts by weight of the above polymer in 100 parts by weight of water with stirring at room temperature was used as an anode body of an aluminum capacitor.
After soaking for a minute, it was dried with a hot air dryer to form a conductive layer on the anode body. The solid electrolytic capacitor thus obtained had a capacitance of 5.0 μF at 120 Hz, and the tangent (tan σ) of the loss angle was 4.9%. Equivalent series resistance (ESR) at 1MHz
Was 140 mΩ.

Example 2 100 mmol of 2-aminoanisole-4-sulfonic acid
Is dissolved in a 4 mol / liter trimethylamine aqueous solution with stirring at 4 ° C., and ammonium peroxodisulfate 100 mm is added.
An aqueous solution of ol was added dropwise. After the dropwise addition was completed, the mixture was further stirred at 25 ° C. for 6 hours, and the reaction product was separated by filtration, washed and dried to obtain 12 g of polymer powder. 1 mol / l P of this polymer
The mixture was stirred for 1 hour in an acetone solution of TS, washed by filtration, and dried to obtain 10 g of a polymer powder having a free sulfo group. The conductivity of this product was 0.1 s / cm. 70 parts by weight of water, 10 parts by weight of the above polymer, 3 parts of isopropyl alcohol
A solution obtained by stirring and dissolving 0 part by weight at room temperature was immersed in the anode body of the aluminum capacitor for 2 minutes and then dried with a hot air dryer to form a conductive layer on the anode body. The solid electrolytic capacitor obtained in this way has a value of 6.
It has a capacitance of 0μF and the tangent of loss angle (tan σ)
Was 5.9%. The equivalent series resistance (ESR) at 1 MHz was 160 mΩ.

Example 3 100 mmol of 2-aminoanisole-4-sulfonic acid
Was dissolved in a 4 mol / l quinoline aqueous solution with stirring at 4 ° C., and an aqueous solution of 100 mmol of ammonium peroxodisulfate was added dropwise. After completion of the dropping, the mixture was further stirred at 25 ° C. for 12 hours, and the reaction product was separated by filtration, washed and dried to obtain 16 g of polymer powder. The conductivity of this product was 0.2 s / cm. A solution prepared by stirring and dissolving 10 parts by weight of the above polymer in 70 parts by weight of water and 30 parts by weight of isopropyl alcohol at room temperature was immersed in the anode body of an aluminum capacitor for 2 minutes and then dried by a hot air dryer to make the anode body conductive. Layers were formed. The solid electrolytic capacitor thus obtained is 120H
In z, it had a capacitance of 6.5 μF and the tangent (tan σ) of the loss angle was 4.2%. Also, 1MHz
The equivalent series resistance (ESR) in was 165 mΩ.

Example 4 3-Amino-4-ethoxybenzenesulfonic acid 100 m
mol was dissolved with stirring at 25 ° C. in a 3 mol / liter 2-methylpyridine (α-picoline) aqueous solution, and an aqueous solution of ammonium peroxodisulfate 100 mmol was added dropwise.
After the dropwise addition was completed, the mixture was further stirred at 25 ° C. for 12 hours, and the reaction product was separated by filtration, washed and dried to obtain 14 g of polymer powder. The conductivity of this product was 0.2 s / cm. 70 parts by weight of water, 10 parts by weight of the above polymer, 3 parts of isopropyl alcohol
A solution obtained by stirring and dissolving 0 part by weight at room temperature was immersed in the anode body of the aluminum capacitor for 2 minutes and then dried with a hot air dryer to form a conductive layer on the anode body. The solid electrolytic capacitor obtained in this way has a value of 6.
It has a capacitance of 5μF and the tangent of loss angle (tan σ)
Was 4.2%. The equivalent series resistance (ESR) at 1 MHz was 165 mΩ.

Example 5 50 mmol of 2-aminoanisole-4-sulfonic acid and 2
50 mmol of aminobenzoic acid was added to 4 mol / l of 3-at 2 ° C.
It was dissolved in an aqueous solution of methylpyridine (β-picoline), and an aqueous solution of 100 mmol of ammonium peroxodisulfate was added dropwise. After completion of dropping, the mixture was further stirred at 25 ° C. for 12 hours, the reaction product was separated by filtration, washed and dried to give about 9 g of polymer powder.
I got it. The conductivity of this product was 0.1 s / cm. A solution prepared by dissolving 10 parts by weight of the above polymer in 80 parts by weight of water and 20 parts by weight of ethylene glycol at room temperature with stirring was immersed in the anode body of the aluminum electrolytic capacitor for 2 minutes and then dried with a hot air dryer to conduct electricity on the anode body. A transparent layer was formed. The solid electrolytic capacitor thus obtained has a frequency of 120 Hz.
At a capacitance of 5.0 μF, the tangent of loss angle (tan σ) was 5.1%. The equivalent series resistance (ESR) at 1 MHz was 155 mΩ.

Example 6 As a film forming metal, a porous sintered body obtained by sintering fine powder of tantalum (using an area of about 20 mm 2 and applying a DC voltage of 100 V in a 0.4 wt% phosphoric acid aqueous solution at 100 ° C.) Then, an insulating film (dielectric film) was formed to serve as an anode body of the capacitor.10 parts by weight of a polymer of 2-aminoanisole-4-sulfonic acid synthesized in Example 2 was added to 60 parts by weight of water and ethanol. A conductive composition was prepared by stirring and dissolving in 40 parts by weight at room temperature .. The capacitor anode body was dipped in the conductive composition solution for 2 minutes and dried with a hot air dryer to form a conductive layer on the anode body. A conductive paste was applied to the capacitor anode body thus obtained and electrode terminals were attached, and the solid electrolytic capacitor thus obtained had an electrostatic capacity of 19.0 μF at 120 Hz. And the tangent (tan σ) of the loss angle was 2.0%, and the equivalent series resistance (ESR) at 1 MHz.
Was 205 mΩ.

Comparative Example 1 100 mmol of aniline was added at 1.0 mol at -5 ° C.
It was dissolved in a hydrochloric acid aqueous solution of 1 / l with stirring, and an aqueous solution of 50 mmol of ammonium peroxodisulfate was added dropwise. After completion of dropping, the mixture was further stirred at 25 ° C. for 6 hours, the reaction product was filtered off and dried to obtain 8 g of a dope type polyaniline powder. 5 g of the obtained doped polyaniline powder was suspended in a 2 mol / l sodium hydroxide aqueous solution, and the suspension was filtered, washed with water and dried to obtain 6 g of dedoped polyaniline powder. A solution prepared by stirring and dissolving 10 parts by weight of the above polymer in 100 parts by weight of N, N-dimethylformamide at room temperature was immersed in the anode body of the aluminum electrolytic capacitor for 2 minutes, and then dried with a hot air dryer to obtain a solution on the anode body. A polyaniline film was formed. This operation was repeated 3 times in total. The polyaniline film-formed capacitor anode body thus obtained was immersed in a p-toluenesulfonic acid aqueous solution for 5 minutes for doping treatment to form a conductive layer on the anode body. The solid electrolytic capacitor thus obtained has a frequency of 120 Hz.
In addition, it had a capacitance of 15.0 μF and the tangent (tan σ) of the loss angle was 8.1%. Also, 1MHz
The equivalent series resistance (ESR) in was 890 mΩ.

Comparative Example 2 On the same anode body as in Example 1, a manganese dioxide layer was formed as a solid electrolyte by impregnating a manganese nitrate aqueous solution and then performing a thermal decomposition treatment. After re-formation, a conductive paste was applied and electrode terminals were attached. The solid electrolytic capacitor thus obtained has a capacitance of 25.0 μF at 120 Hz and a tangent of the loss angle (t
an) was 8.0%. The equivalent series resistance (ESR) at 1 MHz was 1000 mΩ.

Comparative Example 3 On the same anode body as in Example 1, a cyclohexanone solution of an isoquinolinium salt of 7,7,8,8-tetracyanoquinodimethane was impregnated and then pyrolyzed to form a manganese dioxide layer as a solid electrolyte. Was formed. After re-formation, a conductive paste was applied and electrode terminals were attached.
The solid electrolytic capacitor thus obtained has a thickness of 120
At Hz, the capacitance was 22.0 μF, and the tangent (tan σ) of the loss angle was 10.0%. Also, 1
Equivalent series resistance (ESR) at MHz is 1200m
It was Ω.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-6-56987 (JP, A) JP-A-4-268331 (JP, A) JP-A-6-293828 (JP, A) JP-A-8- 143664 (JP, A) JP-A-8-120074 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01G 9/028 C08G 73/00

Claims (5)

(57) [Claims] 1. A dielectric oxide film formed on the surface of a film-forming metal, which mainly has a structural unit having an acidic group and an electron-donating group in the same aromatic ring represented by the general formula (1).
Weight average molecular weight 3000 or more, and the content of the acidic group to the aromatic ring 70% or more, and the conductivity is 0.01S / cm or more soluble aniline-based conductive polymer characterized by using as a solid electrolyte Capacitors. [Chemical 1] (In the formula, R _1, R _2, R _{3, and} R ₄ are electron withdrawing groups, acidic groups, hydrogen, linear or branched alkyl groups having 1 to 4 carbon atoms, alkenyl groups, alkoxy groups, hydroxyl groups, and nitro groups. , And halogen, and at least two of the substituents each represent an acidic group or an electron-withdrawing group.) 2. The solid electrolytic capacitor according to claim 1, wherein the solid electrolyte is a soluble aniline-based conductive polymer having a structural formula represented by the general formula (2). [Chemical 2] (In the formula, R _{5 to} R ₂₀ are a group consisting of an electron withdrawing group, an acidic group, hydrogen, a linear or branched alkyl group having 1 to 4 carbon atoms, an alkenyl group, an alkoxy group, a hydroxyl group, a nitro group, and a halogen. And at least two of the four substituents on each aromatic ring each represent an acidic group or an electron-withdrawing group.) 3. The solid electrolytic capacitor according to claim 1, wherein the acidic group of the soluble aniline-based conductive polymer is a sulfonic acid group and / or a carboxylic acid group. 4. The soluble aniline-based conductive polymer contains at least one aminobenzenesulfonic acid derivative and / or aminobenzoic acid having an acidic group and an electron donating group in the same aromatic ring represented by the general formula (3). The solid electrolytic capacitor according to claim 1, which is a soluble aniline-based conductive polymer chemically oxidized and polymerized in the presence of a basic compound. [Chemical 3] (In the formula, R _21, R _22, R _23, R _{24, and} R ₂₅ are electron withdrawing groups, acidic groups, hydrogen, linear or branched electron withdrawing groups having 1 to 4 carbon atoms, acidic groups, alkyl groups, It is selected from the group consisting of an alkenyl group, an alkoxy group, a hydroxyl group, a nitro group, and a halogen, at least two of which represent an acidic group and an electron-withdrawing group, and the acidic group is preferably a sulfone group or a carboxylic acid group. Be done.) 5. A basic compound containing at least one aminobenzenesulfonic acid derivative and / or aminobenzoic acid having an acidic group and an electron donating group in the same aromatic ring represented by the general formula (3) as set forth in claim 4. A method for producing a soluble aniline-based conductive polymer, which comprises polymerizing with a oxidant in a solution containing a compound.