JP2008135514A - Capacitor and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitor having excellent conductivity of a solid-state electrolytic layer and small ESR (equivalent series resistance). <P>SOLUTION: The capacitor is provided with an anode 11 formed of a porous material of a valve metal, a dielectric material layer 12 formed with oxidation of the front surface of anode 11, and a cathode 13 formed in the front surface side of the dielectric material layer 12. The cathode 13 includes a solid-state electrolytic layer 13a having a π-conjugated conductive polymer, a polyanion, and a compound expressed by the following general expression (1). In the general expression (1), n is an integer ranging from 0 to 5, while R<SP>1</SP>, a hydrogen atom or a desired substitutional group. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a capacitor such as an aluminum electrolytic capacitor, a tantalum electrolytic capacitor, a niobium electrolytic capacitor, and a manufacturing method thereof.

  In recent years, with the digitization of electronic devices, capacitors used in electronic devices are required to reduce impedance (also referred to as equivalent series resistance or ESR) in a high frequency region. Conventionally, in order to meet this requirement, so-called functional capacitors, in which an oxide film of valve metal such as aluminum, tantalum, or niobium is used as a dielectric, and a π-conjugated conductive polymer is formed on this surface as a cathode. Is used.

As shown in Patent Document 1, the structure of this functional capacitor includes an anode made of a valve metal porous body, a dielectric layer formed by oxidizing the surface of the anode, a solid electrolyte layer, carbon It is common to have a cathode having a laminated layer and a silver layer. The capacitor's solid electrolyte layer is a layer composed of π-conjugated conductive polymers such as pyrrole and thiophene, penetrates into the porous body, and comes into contact with a larger area of the dielectric layer to increase its capacitance. In addition, it plays a role of preventing the occurrence of leakage current by repairing the defective portion of the dielectric layer.
As a method for forming a π-conjugated conductive polymer, an electrolytic polymerization method (see Patent Document 2) and a chemical oxidation polymerization method (see Patent Document 3) are widely known.
However, in the electropolymerization method, it is necessary to previously form a conductive layer made of manganese oxide on the surface of the valve metal porous body, which is very complicated, and manganese oxide has low conductivity and high conductivity. There is a problem that the effect of using a conductive π-conjugated conductive polymer is reduced.
In addition, in the chemical oxidation polymerization method, the polymerization time is long, and it is necessary to repeat the polymerization in order to ensure the thickness, so that the production efficiency of the capacitor is low and the conductivity is also low.
Patent Document 4 proposes to enhance the conductivity of the solid electrolyte layer by highly controlling the conditions of the chemical oxidative polymerization method. However, the manufacturing method often complicates the complicated chemical oxidative polymerization method, and it has not been possible to simplify the process and reduce the cost.

Therefore, a method has been proposed in which a π-conjugated conductive polymer is not formed on the dielectric layer by an electrolytic polymerization method or a chemical oxidative polymerization method (see Patent Document 5). Patent Document 5 describes a method of preparing water-soluble polyaniline by polymerizing aniline in the presence of a polymer acid having a sulfo group, a carboxyl group, etc., and applying and drying the polyaniline aqueous solution on the dielectric layer. Has been. However, although this production method is simple, it has low conductivity because it contains a polymer acid in addition to the π-conjugated conductive polymer. Therefore, it has been difficult to obtain a capacitor having a small ESR.
JP 2003-37024 A JP-A-63-158829 JP 63-173313 A Japanese Patent Laid-Open No. 11-74157 JP-A-7-105718

  An object of this invention is to provide the capacitor | condenser which is excellent in the electroconductivity of a solid electrolyte layer, and has small ESR. Moreover, it aims at providing the manufacturing method of the capacitor | condenser which can manufacture a capacitor | condenser with small ESR easily.

[1] In a capacitor comprising an anode made of a porous body of a valve metal, a dielectric layer formed by oxidizing the anode surface, and a cathode formed on the dielectric layer surface side,
A capacitor, wherein the cathode has a solid electrolyte layer containing a π-conjugated conductive polymer, a polyanion, and a compound represented by the following general formula (1).

(In general formula (1), n is an integer of 0 to 5. R ¹ is a hydrogen atom or an arbitrary substituent.)

[2] R ¹ in the general formula (1) is a substituent represented by the general formula (2), and the sum of n in the general formula (1) and m in the general formula (2) is 2 or more. The capacitor according to [1], wherein

(M in the general formula (2) is an integer of 0 to 5.)

[3] The capacitor according to [1], wherein R ¹ in the general formula (1) is a substituent represented by the general formula (3).
NR ² R ^3- (3)
(R ² and R ³ in the general formula (3) are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, a hydroxy group, Represents any of alkyl groups.)

[4] On the surface of the dielectric layer formed by oxidizing the surface of the anode made of a valve metal porous body, a π-conjugated conductive polymer, a polyanion, a compound represented by the following chemical formula (1), and a solvent are added. Applying a conductive polymer solution containing;
And a step of drying the conductive polymer solution applied to the surface of the dielectric layer.

(In general formula (1), n is an integer of 0 to 5. R ¹ is a hydrogen atom or an arbitrary substituent.)

The capacitor of the present invention is excellent in the conductivity of the solid electrolyte layer and has a low ESR.
According to the method for manufacturing a capacitor of the present invention, a capacitor having a small ESR can be easily manufactured.

"Capacitor"
An embodiment of the capacitor of the present invention will be described.
FIG. 1 shows the configuration of the capacitor of this embodiment. The capacitor 10 of this embodiment includes an anode 11 made of a porous body of valve metal, a dielectric layer 12 formed by oxidizing the surface of the anode 11, and a cathode 13 formed on the surface of the dielectric layer 12. And has a schematic configuration.

<Anode>
Examples of the valve metal forming the anode 11 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Of these, aluminum, tantalum, and niobium are preferable. Since these valve metals can form a dense and durable dielectric oxide film (dielectric layer) by electrolytic oxidation treatment, the capacitor capacity can be stably increased.
Specific examples of the anode 11 include those obtained by etching an aluminum foil to increase the surface area and then oxidizing the surface, or oxidizing the surface of a sintered body of tantalum particles and niobium particles into pellets. Can be mentioned. The surface of the anode 11 thus oxidized is uneven.

<Dielectric layer>
The dielectric layer 12 is obtained by, for example, forming the surface of the anode 11 by anodic oxidation in an electrolytic solution such as a diammonium adipate aqueous solution. Therefore, as shown in FIG. 1, the dielectric layer 12 is along the uneven surface of the anode 11.

<Cathode>
The cathode 13 includes a solid electrolyte layer 13a disposed on the dielectric layer 12 side and a conductive layer 13b disposed on the opposite side to the dielectric layer 12 side.
Moreover, a separator can be provided between the solid electrolyte layer 13a and the conductive layer 13b as necessary.

(Solid electrolyte layer)
The solid electrolyte layer 13a is a layer containing, as essential components, a π-conjugated conductive polymer, a polyanion, and a compound represented by the general formula (1).
The thickness of the solid electrolyte layer 13 is preferably 1 to 100 μm.

[Π-conjugated conductive polymer]
The π-conjugated conductive polymer can be used as long as the main chain is an organic polymer having a π-conjugated system. Examples thereof include polypyrroles, polythiophenes, polyacetylenes, polyphenylenes, polyphenylene vinylenes, polyanilines, polyacenes, polythiophene vinylenes, and copolymers thereof. From the viewpoint of easy polymerization and stability in air, polypyrroles, polythiophenes and polyanilines are preferred.
Even if the π-conjugated conductive polymer remains unsubstituted, sufficient conductivity can be obtained. However, in order to further improve conductivity, an alkyl group, a carboxylic acid group, a sulfonic acid group, an alkoxyl group, a hydroxyl group It is preferable to introduce a functional group such as a cyano group into the π-conjugated conductive polymer.

  Specific examples of such π-conjugated conductive polymers include polypyrrole, poly (N-methylpyrrole), poly (3-methylpyrrole), poly (3-octylpyrrole), poly (3-decylpyrrole), Poly (3-dodecylpyrrole), poly (3,4-dimethylpyrrole), poly (3,4-dibutylpyrrole), poly (3-carboxypyrrole), poly (3-methyl-4-carboxypyrrole), poly ( 3-methyl-4-carboxyethylpyrrole), poly (3-methyl-4-carboxybutylpyrrole), poly (3-hydroxypyrrole), poly (3-methoxypyrrole), polythiophene, poly (3-methylthiophene), Poly (3-hexylthiophene), poly (3-heptylthiophene), poly (3-octylthiophene), poly (3-de Ruthiophene), poly (3-dodecylthiophene), poly (3-octadecylthiophene), poly (3-bromothiophene), poly (3,4-dimethylthiophene), poly (3,4-dibutylthiophene), poly ( 3-hydroxythiophene), poly (3-methoxythiophene), poly (3-ethoxythiophene), poly (3-butoxythiophene), poly (3-hexyloxythiophene), poly (3-heptyloxythiophene), poly ( 3-octyloxythiophene), poly (3-decyloxythiophene), poly (3-dodecyloxythiophene), poly (3-octadecyloxythiophene), poly (3,4-dihydroxythiophene), poly (3,4 Dimethoxythiophene), poly (3,4-ethylenedioxythiophene) , Poly (3,4-propylenedioxythiophene), poly (3,4-butenedioxythiophene), poly (3-carboxythiophene), poly (3-methyl-4-carboxythiophene), poly (3-methyl -4-carboxyethylthiophene), poly (3-methyl-4-carboxybutylthiophene), polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), poly (2-anilinesulfonic acid), poly ( 3-anilinesulfonic acid) and the like.

  Among them, from one or two kinds selected from polypyrrole, polythiophene, poly (N-methylpyrrole), poly (3-methylthiophene), poly (3-methoxythiophene), and poly (3,4-ethylenedioxythiophene). The (co) polymer is preferably used from the viewpoints of resistance and reactivity. Furthermore, polypyrrole and poly (3,4-ethylenedioxythiophene) are more preferable from the viewpoint of higher conductivity and improved heat resistance.

[Polyanion]
The polyanion is a homopolymer or copolymer selected from substituted or unsubstituted polyalkylene, substituted or unsubstituted polyalkenylene, substituted or unsubstituted polyimide, substituted or unsubstituted polyamide, substituted or unsubstituted polyester And having a structural unit having an anionic group. Moreover, you may have a structural unit which does not have an anion group as needed.
The polyanion not only solubilizes the π-conjugated conductive polymer in a solvent, but also functions as a dopant for the π-conjugated conductive polymer.

  Here, polyalkylene is a polymer whose main chain is composed of repeating methylene. For example, polyethylene, polypropylene, polybutene, polypentene, polyhexene, polyvinyl alcohol, polyvinylphenol, poly (3,3,3-trifluoropropylene), polyacrylonitrile, polyacrylate, polystyrene and the like can be mentioned.

Polyalkenylene is a polymer composed of structural units containing one or more unsaturated bonds (vinyl groups) in the main chain. Among these, substituted or unsubstituted butenylene is preferable because of the interaction between the unsaturated bond and the π-conjugated conductive polymer and the ease of synthesis using substituted or unsubstituted butadiene as a starting material.
Specific examples of polyalkenylene include propenylene, 1-methylpropenylene, 1-butylpropenylene, 1-decylpropenylene, 1-cyanopropenylene, 1-phenylpropenylene, 1-hydroxypropenylene, 1-butenylene, 1-methyl-1-butenylene, 1-ethyl-1-butenylene, 1-octyl-1-butenylene, 1-pentadecyl-1-butenylene, 2-methyl-1-butenylene, 2-ethyl-1-butenylene, 2- Butyl-1-butenylene, 2-hexyl-1-butenylene, 2-octyl-1-butenylene, 2-decyl-1-butenylene, 2-dodecyl-1-butenylene, 2-phenyl-1-butenylene, 2-butenylene, 1-methyl-2-butenylene, 1-ethyl-2-butenylene, 1-octyl-2-butenylene 1-pentadecyl-2-butenylene, 2-methyl-2-butenylene, 2-ethyl-2-butenylene, 2-butyl-2-butenylene, 2-hexyl-2-butenylene, 2-octyl-2-butenylene, 2- Decyl-2-butenylene, 2-dodecyl-2-butenylene, 2-phenyl-2-butenylene, 2-propylenephenyl-2-butenylene, 3-methyl-2-butenylene, 3-ethyl-2-butenylene, 3-butyl 2-butenylene, 3-hexyl-2-butenylene, 3-octyl-2-butenylene, 3-decyl-2-butenylene, 3-dodecyl-2-butenylene, 3-phenyl-2-butenylene, 3-propylenephenyl- 2-butenylene, 2-pentenylene, 4-propyl-2-pentenylene, 4-butyl-2-pentenylene, 4-he Selected from sil-2-pentenylene, 4-cyano-2-pentenylene, 3-methyl-2-pentenylene, 4-ethyl-2-pentenylene, 3-phenyl-2-pentenylene, 4-hydroxy-2-pentenylene, hexenylene, etc. And polymers containing one or more structural units.

As polyimide, pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, 2,2 ′, 3,3′-tetracarboxydiphenyl ether dianhydride, 2,2 ′-[ Examples include polyimides from anhydrides such as 4,4′-di (dicarboxyphenyloxy) phenyl] propane dianhydride and diamines such as oxydiamine, paraphenylenediamine, metaphenylenediamine, and benzophenonediamine.
Examples of the polyamide include polyamide 6, polyamide 6,6, polyamide 6,10 and the like.
Examples of the polyester include polyethylene terephthalate and polybutylene terephthalate.

When the polyanion has another substituent, examples of the substituent include an alkyl group, a hydroxyl group, an amino group, a cyano group, a phenyl group, a phenol group, an ester group, an alkoxyl group, and a carbonyl group. In view of solubility in a solvent, heat resistance, compatibility with a resin, and the like, an alkyl group, a hydroxyl group, a phenol group, and an ester group are preferable.
Alkyl groups can increase solubility and dispersibility in polar or nonpolar solvents, compatibility and dispersibility in resins, etc., and hydroxyl groups form hydrogen bonds with other hydrogen atoms and the like. It can be made easy, and the solubility in an organic solvent, the compatibility with a resin, the dispersibility, and the adhesiveness can be increased. In addition, the cyano group and the hydroxyphenyl group can increase the compatibility and solubility in the polar resin, and can also increase the heat resistance.
Among the above substituents, an alkyl group, a hydroxyl group, an ester group, and a cyano group are preferable.

Examples of the alkyl group include chain alkyl groups such as methyl, ethyl, propyl, butyl, isobutyl, t-butyl, pentyl, hexyl, octyl, decyl, and dodecyl, and cycloalkyl groups such as cyclopropyl, cyclopentyl, and cyclohexyl. . In consideration of solubility in an organic solvent, dispersibility in a resin, steric hindrance, and the like, an alkyl group having 1 to 12 carbon atoms is more preferable.
Examples of the hydroxyl group include a hydroxyl group directly bonded to the main chain of the polyanion or a hydroxyl group bonded via another functional group. Examples of other functional groups include an alkyl group having 1 to 7 carbon atoms, an alkenyl group having 2 to 7 carbon atoms, an amide group, and an imide group. Hydroxyl groups are substituted at the ends or in these functional groups. In these, the hydroxyl group couple | bonded with the terminal of the C1-C6 alkyl group couple | bonded with the principal chain is more preferable from the compatibility to resin and the solubility to an organic solvent.
Examples of the ester group include an alkyl ester group directly bonded to the main chain of the polyanion, an aromatic ester group, and an alkyl ester group or an aromatic ester group having another functional group interposed therebetween.
Examples of the cyano group include a cyano group directly bonded to the main chain of the polyanion, a cyano group bonded to the terminal of the alkyl group having 1 to 7 carbon atoms bonded to the main chain of the polyanion, and 2 carbon atoms bonded to the main chain of the polyanion. And a cyano group bonded to the terminal of the alkenyl group of ˜7.

  The anion group of the polyanion may be a functional group capable of undergoing chemical oxidation doping to the π-conjugated conductive polymer. Among them, from the viewpoint of ease of production and stability, a monosubstituted sulfate group, A monosubstituted phosphate group, a phosphate group, a carboxyl group, a sulfo group and the like are preferable. Furthermore, from the viewpoint of the doping effect of the functional group on the π-conjugated conductive polymer, a sulfo group, a monosubstituted sulfate group, and a carboxyl group are more preferable.

Specific examples of polyanions include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic acid ethyl sulfonic acid, polyacrylic acid butyl sulfonic acid, poly (2-acrylamido-2-methylpropane sulfonic acid), polyisoprene. Sulfonic acid, polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacryl carboxylic acid, polymethacryl carboxylic acid, poly (2-acrylamido-2-methylpropane carboxylic acid), polyisoprene carboxylic acid, polyacrylic acid, etc. Can be mentioned. These homopolymers may be sufficient and 2 or more types of copolymers may be sufficient.
Among these, polystyrene sulfonic acid, polyisoprene sulfonic acid, polyacrylic acid ethyl sulfonic acid, and polyacrylic acid butyl sulfonic acid are preferable. These polyanions can mitigate thermal decomposition of the π-conjugated conductive polymer.

  The degree of polymerization of the polyanion is preferably in the range of 10 to 100,000 monomer units, and more preferably in the range of 50 to 10,000 from the viewpoint of solvent solubility and conductivity.

  The content of the polyanion is preferably in the range of 0.1 to 10 mol, and more preferably in the range of 1 to 7 mol, with respect to 1 mol of the π-conjugated conductive polymer. When the polyanion content is less than 0.1 mol, the doping effect on the π-conjugated conductive polymer tends to be weak, and the conductivity may be insufficient. In addition, the dispersibility and solubility in the solvent are reduced, making it difficult to obtain a uniform dispersion. On the other hand, when the polyanion content exceeds 10 mol, the content of the π-conjugated conductive polymer in the solid electrolyte layer 13a decreases, and it is difficult to obtain sufficient conductivity.

[Compound represented by general formula (1)]
R ¹ in the compound represented by the general formula (1) (hereinafter referred to as Compound 1) is a hydrogen atom or an arbitrary substituent. Here, the substituent is not particularly limited, and examples thereof include an organic group (for example, an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an alkoxyl group, and the like). The substituent represented by (2) and the substituent represented by formula (3) are preferred.
R ² and R ³ in the general formula (3) are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, etc.) , Alkenyl groups (for example, ethylene groups, propylene groups, etc.), cycloalkyl groups (for example, cyclohexyl groups, etc.), aryl groups (for example, phenyl groups, naphthyl groups, etc.), aralkyl groups, hydroxyalkyl groups (for example, hydroxymethyl groups) , Hydroxyethyl group, etc.).

  Specific examples of compound 1 include 2-hydroxybenzophenone, 4-hydroxybenzophenone, 2-hydroxyacetophenone, 4-hydroxyacetophenone, 3,4,5-trihydroxyacetophenone, 2-hydroxybenzaldehyde, 4-hydroxybenzaldehyde, 3, 4,5-trihydroxybenzaldehyde, 2-hydroxybenzoic acid, 4-hydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid, methyl 2-hydroxybenzoate, methyl 4-hydroxybenzoate, 3,4,5 -Methyl-hydroxybenzoate, phenyl 4-hydroxybenzoate, etc. are mentioned.

When R ¹ is a substituent represented by the general formula (2), the sum of n in the general formula (1) and m in the general formula (2) is 2 or more, and 6 or less in that it can be easily synthesized. It is preferable that
The benzene ring in the general formula (2) may be substituted with a substituent. Examples of the substituent include an alkyl group, an alkenyl group, an aryl group, a hydroxyl group, an amino group, an imino group, a fluorine atom, a chlorine atom, a bromine atom, and a mercapto group.
Specific examples of the compound 1 in the case where R ¹ is a substituent represented by the general formula (2) include 2,2′-dihydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,4′-dihydroxybenzophenone, 4 , 4′-dihydroxybenzophenone, 2,4,4′-trihydroxybenzophenone, 3,4,5-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,3,4,4′-tetrahydroxybenzophenone 2,3 ′, 4,4′-tetrahydroxybenzophenone, 2,3,3 ′, 4,4 ′, 5′-hexahydroxybenzophenone, and the like.
Among these benzophenone compounds, those having a hydroxyl group at the 4-position or the 4′-position are preferable because the conductivity can be further increased.

Specific examples of the compound 1 in the case where R ¹ is a substituent represented by the general formula (3) include 2-hydroxybenzamide, 3-acetamidophenol, 4-acetamidophenol, N-phenylbenzamide, hydroxyphenyl methacrylamide , Hydroxyphenyldiethylamide, 4-hydroxybenzamide, 3,4,5-trihydroxybenzamide and the like.

  The molecular weight of Compound 1 is preferably 5000 or less, more preferably 1000 or less, and particularly preferably 500 or less. When the molecular weight exceeds 5000, the solubility in an aqueous solvent tends to decrease.

  The content of Compound 1 in the solid electrolyte layer 13a is preferably 0.1 to 100 molar equivalents, more preferably 0.5 to 50 molar equivalents relative to 1 mol of anionic groups of the polyanion. It is especially preferable that it is 0.0-20 molar equivalent. When the content of Compound 1 is less than the lower limit, the effect of improving the conductivity due to the addition of Compound 1 is less likely to be exhibited. When the content exceeds the upper limit, the concentration of the π-conjugated conductive polymer is decreased. The conductivity tends to be low.

[Dopant]
In solid electrolyte layer 13a, in order to improve electroconductivity, you may contain other dopants other than a polyanion.
Other dopants may be donor-type or acceptor-type as long as the π-conjugated conductive polymer can be oxidized and reduced.
Specific examples of donor dopant and acceptor dopant are shown below.

Donor-type dopants Examples of donor-type dopants include alkali metals such as sodium and potassium, alkaline earth metals such as calcium and magnesium, tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, and dimethyl. And quaternary amine salt compounds such as diethylammonium.

-Acceptor dopant As an acceptor dopant, a halogen compound, a Lewis acid, a proton acid, an organic cyano compound, an organometallic compound etc. can be used, for example.
Furthermore, examples of the halogen compound include chlorine (Cl ₂ ), bromine (Br ₂ ), iodine (I ₂ ), iodine chloride (ICl), iodine bromide (IBr), and iodine fluoride (IF). .
Examples of the Lewis acid include PF ₅ , AsF ₅ , SbF ₅ , BF ₅ , BCl ₅ , BBr ₅ , SO _{3 and the} like.
As the organic cyano compound, a compound containing two or more cyano groups in a conjugated bond can be used. For example, tetracyanoethylene, tetracyanoethylene oxide, tetracyanobenzene, tetracyanoquinodimethane, tetracyanoazanaphthalene, and the like can be given.

  Examples of the protonic acid include inorganic acids and organic acids. Furthermore, examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, borohydrofluoric acid, hydrofluoric acid, and perchloric acid. Examples of organic acids include organic carboxylic acids and organic sulfonic acids.

  As the organic carboxylic acid, aliphatic, aromatic, cycloaliphatic or the like containing one or more carboxyl groups can be used. For example, formic acid, acetic acid, oxalic acid, benzoic acid, phthalic acid, maleic acid, fumaric acid, malonic acid, tartaric acid, citric acid, lactic acid, succinic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, nitroacetic acid, And triphenylacetic acid.

  As the organic sulfonic acid, aliphatic, aromatic, cycloaliphatic or the like containing one or more sulfo groups can be used. Examples of those containing one sulfo group include methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 1-butanesulfonic acid, 1-hexanesulfonic acid, 1-heptanesulfonic acid, 1-octanesulfonic acid, 1-nonanesulfonic acid, 1-decanesulfonic acid, 1-dodecanesulfonic acid, 1-tetradecanesulfonic acid, 1-pentadecanesulfonic acid, 2-bromoethanesulfonic acid, 3-chloro-2-hydroxypropanesulfonic acid, trifluoromethane Sulfonic acid, colistin methanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, aminomethanesulfonic acid, 1-amino-2-naphthol-4-sulfonic acid, 2-amino-5-naphthol-7-sulfone Acid, 3-aminopropanesulfonic acid, N-cyclohexyl-3- Minopropanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, ethylbenzenesulfonic acid, propylbenzenesulfonic acid, butylbenzenesulfonic acid, pentylbenzenesulfonic acid, hexylbenzenesulfonic acid, heptylbenzenesulfonic acid, octylbenzene Sulfonic acid, nonylbenzenesulfonic acid, decylbenzenesulfonic acid, undecylbenzenesulfonic acid, dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, 2,4-dimethylbenzenesulfonic acid, dipropylbenzenesulfone Acid, butylbenzenesulfonic acid, 4-aminobenzenesulfonic acid, o-aminobenzenesulfonic acid, m-aminobenzenesulfonic acid, 4-amino-2-chlorotolue -5-sulfonic acid, 4-amino-3-methylbenzene-1-sulfonic acid, 4-amino-5-methoxy-2-methylbenzenesulfonic acid, 2-amino-5-methylbenzene-1-sulfonic acid, 4 -Amino-2-methylbenzene-1-sulfonic acid, 5-amino-2-methylbenzene-1-sulfonic acid, 4-amino-3-methylbenzene-1-sulfonic acid, 4-acetamido-3-chlorobenzenesulfonic acid 4-chloro-3-nitrobenzenesulfonic acid, p-chlorobenzenesulfonic acid, naphthalenesulfonic acid, methylnaphthalenesulfonic acid, propylnaphthalenesulfonic acid, butylnaphthalenesulfonic acid, pentylnaphthalenesulfonic acid, dimethylnaphthalenesulfonic acid, 4-amino- 1-naphthalenesulfonic acid, 8-chloronaphthalene-1 Acid, naphthalenesulfonic acid-formalin polycondensate, a sulfonic acid compound containing a sulfo group such as melamine sulfonic acid-formalin polycondensates, and the like.

  Examples of those containing two or more sulfo groups include ethanedisulfonic acid, butanedisulfonic acid, pentanedisulfonic acid, decanedisulfonic acid, m-benzenedisulfonic acid, o-benzenedisulfonic acid, p-benzenedisulfonic acid, and toluenedisulfonic acid. Xylene disulfonic acid, chlorobenzene disulfonic acid, fluorobenzene disulfonic acid, aniline-2,4-disulfonic acid, aniline-2,5-disulfonic acid, dimethylbenzene disulfonic acid, diethylbenzene disulfonic acid, dibutylbenzene sulfonic acid, naphthalene disulfonic acid, Methyl naphthalene disulfonic acid, ethyl naphthalene disulfonic acid, dodecyl naphthalene disulfonic acid, pentadecyl naphthalene disulfonic acid, butyl naphthalene disulfonic acid, 2-amino-1,4-benze Disulfonic acid, 1-amino-3,8-naphthalenedisulfonic acid, 3-amino-1,5-naphthalenedisulfonic acid, 8-amino-1-naphthol-3,6-disulfonic acid, 4-amino-5-naphthol- 2,7-disulfonic acid, anthracene disulfonic acid, butylanthracene disulfonic acid, 4-acetamido-4'-isothio-cyanatostilbene-2,2'-disulfonic acid, 4-acetamido-4'-isothiocyanatostilbene-2 , 2'-disulfonic acid, 4-acetamido-4'-maleimidyl stilbene-2,2'-disulfonic acid, 1-acetoxypyrene-3,6,8-trisulfonic acid, 7-amino-1,3 6-naphthalene trisulfonic acid, 8-aminonaphthalene-1,3,6-trisulfonic acid, 3-amino-1,5,7-naphth Rent Li sulfonic acid and the like.

[Electrolyte]
In the solid electrolyte layer 13a, the π-conjugated conductive polymer is often formed as particles having a particle diameter of 1 to 500 nm. For this reason, the π-conjugated conductive polymer does not reach the deepest part of the fine voids on the surface of the dielectric layer 12, and it may be difficult to draw out the capacitance. For this reason, it is preferable to replenish the capacity by impregnating the electrolyte solution into the solid electrolyte layer 13a as necessary.

The electrolytic solution is not particularly limited as long as it has high conductivity, and a known electrolyte is dissolved in a known solvent.
Examples of the solvent in the electrolytic solution include alcohol solvents such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, and glycerin; lactone solvents such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; Examples thereof include amide solvents such as N-methylformamide, N, N-dimethylformamide, N-methylacetamide and N-methylpyrrolidinone, nitrile solvents such as acetonitrile and 3-methoxypropionitrile, water and the like.
Examples of the electrolyte include adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, maleic acid, toluic acid, enanthic acid, malonic acid, formic acid, 1,6-decanedicarboxylic acid, 5,6 -Decane dicarboxylic acid such as decanedicarboxylic acid, octane dicarboxylic acid such as 1,7-octane dicarboxylic acid, organic acid such as azelaic acid and sebacic acid, or boric acid, polyhydric alcohol of boric acid obtained from boric acid and polyhydric alcohol Complex compounds, inorganic acids such as phosphoric acid, carbonic acid, and silicic acid are used as anionic components, and primary amines (methylamine, ethylamine, propylamine, butylamine, ethylenediamine, etc.), secondary amines (dimethylamine, diethylamine, dipropylamine, Methylethylamine, diphenylamine, etc.), tertiary amine (trimethyl) Amine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo (5,4,0) -undecene-7, etc.), tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, Examples thereof include electrolytes containing methyltriethylammonium, dimethyldiethylammonium, etc.) as cationic components.

(Conductive layer)
The conductive layer 13b is composed of a layer of carbon, silver, aluminum or the like, for example. When the conductive layer 13b is made of carbon, silver or the like, it can be formed from a conductive paste containing a conductor such as carbon or silver. When the conductive layer 13b is made of aluminum, it is made of an aluminum foil.

It is considered that the compound 1 contained in the solid electrolyte layer 13 of the capacitor 10 described above easily interacts with the anion group of the polyanion, and as a result, the polyanions can be brought close to each other. Therefore, π-conjugated conductive polymers adsorbed on the polyanion by doping can also be brought close to each other. Thereby, it is considered that the energy required for hopping, which is a conductive phenomenon between π-conjugated conductive polymers, is reduced, and the overall electrical resistance is reduced (conductivity is increased). As a result of the increased conductivity of the solid electrolyte layer 13a, the ESR of the capacitor 10 decreases.
In addition, since Compound 1 releases hydrogen, radicals generated during oxidative degradation of the π-conjugated conductive polymer can be deactivated. Thereby, the chain reaction of radicals can be blocked and the progress of deterioration can be suppressed, so that the heat resistance and stability can be increased.

"Capacitor manufacturing method"
The method for manufacturing the capacitor 10 includes a step of applying a conductive polymer solution to the surface of the dielectric layer 12 formed by oxidizing the surface of the anode 11 made of a porous body of valve metal (hereinafter referred to as step A). The conductive polymer solution applied to the surface of the dielectric layer 12 is dried to form the solid electrolyte layer 13a (hereinafter referred to as “process B”), and the conductive paste is applied on the solid electrolyte layer 13a to conduct electricity. And a step of forming the layer 13b (hereinafter referred to as step C).

[Step A]
The conductive polymer solution used in step A contains a π-conjugated conductive polymer, a polyanion, compound 1, and a solvent. As the π-conjugated conductive polymer, polyanion, and compound 1, those described above are used.

  As an example of a method for preparing the conductive polymer solution, first, a precursor monomer that forms a π-conjugated conductive polymer in a solvent in the presence of a polyanion is chemically oxidatively polymerized using an oxidizing agent, Excess oxidizing agent and precursor monomer are removed to prepare a solution containing a complex in which a π-conjugated conductive polymer and a polyanion are complexed. Next, Compound 1 is added to obtain a conductive polymer solution.

  Examples of the solvent include, but are not limited to, alcohol solvents such as methanol, ethanol, and isopropanol (IPA), amide solvents such as N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), and dimethylformamide (DMF), A ketone solvent such as methyl ethyl ketone (MEK), acetone, or cyclohexanone, an ester solvent such as ethyl acetate or butyl acetate, toluene, xylene, water, or the like may be used alone or in combination. Among them, the use of water or an alcohol-based solvent is preferable because the load on the environment is small.

  Examples of the oxidizing agent include peroxodisulfates such as ammonium peroxodisulfate (ammonium persulfate), sodium peroxodisulfate (sodium persulfate), potassium peroxodisulfate (potassium persulfate), ferric chloride, Transition metal compounds such as ferric sulfate, ferric nitrate and cupric chloride, metal halogen compounds such as boron trifluoride, metal oxides such as silver oxide and cesium oxide, peroxides such as hydrogen peroxide and ozone Products, organic peroxides such as benzoyl peroxide, oxygen and the like.

The conductive polymer solution is preferably adjusted to a pH of 3 to 13 at 25 ° C, more preferably 5 to 11. If the pH of the conductive polymer solution is adjusted to 3 or more, corrosion of the dielectric layer 12 or the conductive layer 13b by the conductive polymer solution can be prevented. However, when the pH exceeds 13, the conductivity of the π-conjugated conductive polymer tends to decrease.
In order to adjust the pH of the conductive polymer solution to 3 to 13, an alkaline compound may be added.

[Step B]
Examples of the method for applying the conductive polymer solution in the step B to the surface of the dielectric layer 12 include known methods such as coating, dipping, and spraying. Examples of the drying method include hot air drying and vacuum drying.

[Step C]
Examples of the conductive paste used in step C include carbon paste and silver paste.

  In the capacitor manufacturing method described above, since the solid electrolyte layer 13a is formed by applying and drying a conductive polymer solution, the process is simple, suitable for mass production, and low cost. In addition, since the conductive polymer solution contains the π-conjugated conductive polymer, the polyanion, and the compound 1, the hopping energy can be reduced, and the π-conjugated conductive in the solid electrolyte layer 13a. Degradation of the polymer can be prevented. Therefore, since the conductivity of the solid electrolyte layer 13a can be increased, the ESR of the capacitor can be reduced.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Example 1)
(1) Preparation of conductive polymer solution 14.2 g (0.1 mol) of 3,4-ethylenedioxythiophene and 27.5 g (0.15 mol) of polystyrene sulfonic acid (2,000 ml of ion-exchanged water) (Molecular weight; about 150,000) was mixed at 20 ° C.
29.64 g (0.13 mol) of ammonium persulfate and 8.0 g (0.02 mol) of ferric sulfate dissolved in 200 ml of ion-exchanged water were kept at 20 ° C. while stirring the mixed solution thus obtained. The oxidation catalyst solution was added and stirred for 3 hours to react.
The resulting reaction solution was dialyzed to remove unreacted monomers, oxidizing agent, and oxidation catalyst, and a solution containing about 1.5% by mass of polystyrenesulfonic acid-doped poly (3,4-ethylenedioxythiophene) (hereinafter, This was referred to as a complex solution).
Then, after stirring, 0.36 g of 25% by mass of ammonia water was added to 100 g of this composite solution, and then 2.5 g of 3,4,5-trihydroxybenzaldehyde was added to make the pH 8.5 conductive. A functional polymer solution was obtained.

(2) Manufacture of capacitor After connecting the anode lead terminal to the etched aluminum foil (anode foil), a voltage of 100 V was applied in an aqueous solution of 10% by mass of diammonium adipate to form (oxidize) the aluminum foil. A dielectric layer was formed on the surface to obtain a capacitor intermediate.
Next, a counter aluminum cathode foil with a cathode lead terminal welded to the anode foil of the capacitor intermediate was laminated through a cellulose separator, and this was wound up to obtain a capacitor element.
The capacitor element is immersed in the conductive polymer solution prepared in (1) under reduced pressure and then dried for 60 minutes with a hot air dryer at 120 ° C. three times, so that the capacitor intermediate body has a surface on the dielectric layer side. A solid electrolyte layer was formed.
Next, the capacitor element on which the solid electrolyte layer was formed was housed in an aluminum case and sealed with a sealing rubber to produce a capacitor.
About the produced capacitor, the initial value of the electrostatic capacitance in 120 Hz and the equivalent series resistance (ESR) in 100 kHz was measured using LCZ meter 2345 (made by NF circuit design block company). The measurement results are shown in Table 1.

(Example 2)
A capacitor was fabricated in the same manner as in Example 1 except that 4.5 g of hydroxybenzamide was used instead of 2.5 g of 3,4,5-trihydroxybenzaldehyde. Then, the initial values of capacitance and ESR were measured in the same manner as in Example 1. The measurement results are shown in Table 1.

(Example 3)
A capacitor was fabricated in the same manner as in Example 1 except that 4.5 g of 3,4,5-trihydroxybenzamide was used instead of 2.5 g of 3,4,5-trihydroxybenzaldehyde. Then, the initial values of capacitance and ESR were measured in the same manner as in Example 1. The measurement results are shown in Table 1.

Example 4
A capacitor was fabricated in the same manner as in Example 1 except that 4.5 g of hydroxyphenylbenzmethacrylamide was used instead of 2.5 g of 3,4,5-trihydroxybenzaldehyde. Then, the initial values of capacitance and ESR were measured in the same manner as in Example 1. The measurement results are shown in Table 1.

(Example 5)
Similar to Example 1 except that 0.36 g of 25% by mass aqueous ammonia and 30 g of ethanol were mixed with 100 g of the complex solution, and then 3.0 g of 2,3,4-trihydroxybenzophenone was added. Thus, a capacitor was produced. Then, in the same manner as in Example 1, the initial values of capacitance and ESR were measured. The measurement results are shown in Table 1.

(Comparative Example 1)
A capacitor was produced in the same manner as in Example 1 except that 100 g of the composite solution was used as it was as the conductive polymer solution. Then, in the same manner as in Example 1, the initial values of capacitance and ESR were measured. The measurement results are shown in Table 1.

(Comparative Example 2)
A capacitor was produced in the same manner as in Example 1 except that only 0.36 g of 25% by mass ammonia water was added to 100 g of the composite solution. Then, in the same manner as in Example 1, the initial values of capacitance and ESR were measured. The measurement results are shown in Table 1.

The capacitors of Examples 1 to 5 in which the solid electrolyte layer contained Compound 1 had a low ESR. Moreover, no decrease in capacitance was observed.
The capacitors of Comparative Examples 1 and 2 in which the solid electrolyte layer did not contain Compound 1 had a large ESR.

It is a cross-sectional schematic diagram which shows one embodiment of the capacitor | condenser of this invention.

Explanation of symbols

10 Capacitor 11 Anode 12 Dielectric Layer 13 Cathode 13a Solid Electrolyte Layer

Claims (4)

In a capacitor comprising an anode made of a porous body of valve metal, a dielectric layer formed by oxidizing the anode surface, and a cathode formed on the surface side of the dielectric layer,
A capacitor, wherein the cathode has a solid electrolyte layer containing a π-conjugated conductive polymer, a polyanion, and a compound represented by the following general formula (1).

(In general formula (1), n is an integer of 0 to 5. R ¹ is a hydrogen atom or an arbitrary substituent.) R ¹ in the general formula (1) is a substituent represented by the general formula (2), and the total of n in the general formula (1) and m in the general formula (2) is 2 or more. The capacitor according to claim 1.

(M in the general formula (2) is an integer of 0 to 5.) 2. The capacitor according to claim 1, wherein R ¹ in the general formula (1) is a substituent represented by the general formula (3).
NR ² R ^3- (3)
(R ² and R ³ in the general formula (3) are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 5 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, a hydroxy group, Represents any of alkyl groups.) Conductivity containing a π-conjugated conductive polymer, a polyanion, a compound represented by the following chemical formula (1), and a solvent on the surface of a dielectric layer formed by oxidizing the surface of an anode made of a porous body of valve metal Applying a functional polymer solution;
And a step of drying the conductive polymer solution applied to the surface of the dielectric layer.

(In general formula (1), n is an integer of 0 to 5. R ¹ is a hydrogen atom or an arbitrary substituent.)

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