WO2014136796A1

WO2014136796A1 - Solid electrolyte capacitor and method for producing same

Info

Publication number: WO2014136796A1
Application number: PCT/JP2014/055511
Authority: WO
Inventors: 泰之田川; 村田　直樹; 元章荒木; 大久保　隆
Original assignee: 昭和電工株式会社
Priority date: 2013-03-05
Filing date: 2014-03-04
Publication date: 2014-09-12
Also published as: JP6408459B2; TWI632571B; TW201447943A; JPWO2014136796A1

Abstract

The present invention provides a solid electrolyte capacitor that has superior capacitor characteristics using a dispersion containing a conductive polymer, a polyanion, and a dispersing medium. The solid electrolyte capacitor, which uses as the solid electrolyte the result formed by eliminating all or a portion of the dispersing medium from a dispersion containing a conductive polymer, a polyanion, and a dispersing medium, is characterized in that the dispersion is produced by polymerizing a monomer in the dispersing medium, and a step is included for adding the polyanion partway through the polymerization.

Description

Solid electrolytic capacitor and manufacturing method thereof

The present invention relates to a solid electrolytic capacitor using a conductive polymer as a solid electrolyte and a method for manufacturing the same.

A solid electrolytic capacitor using a conductive polymer as a solid electrolyte has been proposed. Known examples of solid electrolytic capacitors include capacitors such as aluminum, tantalum, and niobium (such as aluminum electrolytic capacitors, tantalum electrolytic capacitors, and niobium electrolytic capacitors).

Known conductive polymers used in solid electrolytic capacitors include polythiophene, polypyrrole, polyaniline, polyacetylene, polyphenylene, poly (p-phenylene-vinylene), polyacene, polythiophene vinylene, and derivatives thereof. Further, a technique of doping a polyanion such as polystyrene sulfonic acid as a counter anion of a conjugated conductive polymer is known.

As a general method for forming a solid electrolyte layer, a monomer solution and an oxidant solution for obtaining a conductive polymer are applied on a dielectric oxide film formed on a metal surface having a valve action. Thus, chemical polymerization or electrolytic polymerization is known. On the other hand, in recent years, a method of forming a solid electrolyte layer by applying a conductive polymer aqueous solution or suspension has been proposed.

For example, Patent Document 1 discloses a step of impregnating a capacitor element with a liquid in which fine particles of a conductive polymer are dispersed in an aqueous medium to form a first solid electrolyte layer, and a surface of the first solid electrolyte layer. Then, the second solid electrolyte layer is formed by impregnating the solution containing the heterocyclic monomer and the solution containing the oxidizing agent individually or by impregnating the mixed solution containing the heterocyclic monomer and the oxidizing agent. The manufacturing method which comprised the process is shown.

In Patent Document 2, a conductive polymer layer is formed as a solid electrolyte layer by chemical polymerization of a polymerizable monomer on a capacitor element in which a dielectric oxide film is formed on the surface of a sintered body obtained by sintering valve metal powder. After that, the capacitor element is immersed in a conductive polymer solution, or the conductive polymer solution is applied to the capacitor element and dried to make the conductive polymer layer thicker on the conductive polymer layer by chemical polymerization. The method of forming the layer is shown.

Japanese Patent Laid-Open No. 2003-100561 JP 2005-109252 A

With recent miniaturization and generalization of electronic devices, there is a demand for smaller electrolytic capacitors and improved high-frequency performance. In particular, the impedance characteristics in the high frequency region of solid electrolytic capacitors have been demanded more than ever.
By the way, the conductive polymer tends to aggregate in the dispersion medium, and the dispersion containing the conductive polymer may become highly viscous during the polymerization. High viscosity dispersions are inconvenient for industrial handling. In addition, as required performance of a solid electrolytic capacitor, a design capacity and low ESR (equivalent series resistance) are required. In order to realize these required performances, higher conductivity and impregnation into the dielectric film are required for the conductive polymer dispersion.

An object of the present invention is to provide a solid electrolytic capacitor having excellent capacitor characteristics by using a dispersion containing a conductive polymer, a polyanion and a dispersion medium.

The present invention relates to the following [1] to [16].
[1] A solid electrolytic capacitor having a porous body having at least an anode body made of a valve metal, a dielectric coating formed on the surface of the anode body, and a solid electrolyte formed on the surface of the porous body. The solid electrolyte is formed by removing a part or all of a dispersion medium from a dispersion liquid containing a conductive polymer, a polyanion and a dispersion medium, and the dispersion liquid is a single amount in the dispersion medium. A solid electrolytic capacitor produced by polymerizing a body, comprising a step of adding a polyanion in the course of the polymerization.
[2] The solid electrolytic capacitor according to [1], wherein the monomer is a thiophene derivative represented by the following formula (I).

(In Formula (I), R ¹ and R ² each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 18 carbon atoms, or an optionally substituted carbon group having 1 to 18 represents an alkoxy group having 18 or an optionally substituted alkylthio group having 1 to 18 carbon atoms, or R ¹ and R ² are a combination of R ¹ and R ² and R ¹ and R ² being Along with each carbon atom to be bonded, an alicyclic ring having 3 to 10 carbon atoms which may have a substituent, an aromatic ring having 6 to 10 carbon atoms which may have a substituent, and a substituent A C2-C10 oxygen atom-containing heterocycle, a C2-C10 sulfur atom-containing heterocycle which may have a substituent, or a C2-C10 which may have a substituent Represents a heterocycle containing a sulfur atom and an oxygen atom.)
[3] The solid electrolytic capacitor according to [1] or [2], wherein the polyanion is a polymer having a group consisting of sulfonic acid or a salt thereof.
[4] The solid electrolytic capacitor as described in any one of [1] to [3], wherein ultrasonic irradiation is performed in the course of the polymerization.
[5] A step of applying a dispersion liquid containing a conductive polymer, a polyanion, and a dispersion medium to the surface of a porous body having at least an anode body made of a valve metal and a dielectric coating formed on the surface of the anode body. And a step of forming a solid electrolyte by removing a part or all of the dispersion medium, wherein the dispersion polymerizes monomers in the dispersion medium. A method for producing a solid electrolytic capacitor, comprising a step of adding a polyanion in the course of the polymerization.
[6] The dispersion according to [5], wherein the dispersion includes a step of initiating polymerization of the monomer in the presence of an oxidizing agent, and a step of adding a polyanion during the polymerization. Manufacturing method for solid electrolytic capacitor.
[7] The method for producing a solid electrolytic capacitor as described in [5] or [6] above, wherein 1 to 100% by mass of the total amount of the polyanion is added to the dispersion medium during the polymerization of the monomer.
[8] The solid electrolytic capacitor according to any one of [5] to [7], wherein 20 to 80% by mass of the total amount of the polyanion is added to the dispersion medium during the polymerization of the monomer. Production method.
[9] The solid electrolytic capacitor as described in any one of [5] to [8] above, wherein 0 to 99% by mass of the total amount of the polyanion is added to the dispersion medium before the polymerization of the monomer is started. Manufacturing method.
[10] The production of the solid electrolytic capacitor as described in any one of [5] to [9], wherein a total amount of the polyanion of 20 to 80% by mass is added to the dispersion medium before the polymerization of the monomer is started. Method.
[11] The method according to any one of [5] to [10], wherein the polyanion is continuously or intermittently added to the dispersion medium during the polymerization of the monomer in the dispersion medium. A method for producing a solid electrolytic capacitor.
[12] The rate of addition of the polyanion to the dispersion medium during the polymerization of the monomer in the dispersion medium is 1 to 1000 parts by mass with respect to 100 parts by mass of the monomer in the dispersion medium. The method for producing a solid electrolytic capacitor according to any one of [5] to [11], wherein
[13] The rate of addition of the polyanion to the dispersion medium during the polymerization of the monomer in the dispersion medium is 10 to 100 parts by mass with respect to 100 parts by mass of the monomer in the dispersion medium. 6. The method for producing a solid electrolytic capacitor as described in any one of [5] to [12], wherein
[14] The method for producing a solid electrolytic capacitor as described in any one of [5] to [13] above, wherein the polymerization temperature is 5 to 80 ° C.
[15] The method for producing a solid electrolytic capacitor as described in any one of [5] to [14], wherein ultrasonic irradiation is performed in the course of the polymerization.
[16] The method for producing a solid electrolytic capacitor as described in any one of [5] to [15] above, wherein stirring with a stirring blade and ultrasonic irradiation are performed during the polymerization.

According to the present invention, a solid electrolytic capacitor having excellent capacitor characteristics can be obtained by using a conductive polymer dispersion excellent in impregnation into a dielectric coating.

[Solid electrolytic capacitor]
The solid electrolytic capacitor of the present invention has a porous body having at least an anode body made of a valve metal, a dielectric film formed on the surface of the anode body, and a solid electrolyte layer formed on the surface of the porous body. A solid electrolytic capacitor, wherein the solid electrolyte is formed by removing a part or all of a dispersion medium from a dispersion liquid containing a conductive polymer, a polyanion, and a dispersion medium. A solid electrolytic capacitor produced by polymerizing a monomer in a dispersion medium, comprising a step of adding a polyanion in the course of the polymerization.

<Porous body>
The anode body for forming the porous body is not particularly limited as long as it is used for a solid electrolytic capacitor. For example, a valve metal powder having a high surface area is sintered, or a valve metal foil is etched. What is obtained can be used. Examples of the valve metal include at least one of Al, Be, Bi, Mg, Ge, Hf, Nb, Sb, Si, Sn, Ta, Ti, V, W and Zr, and at least one of these metals and other elements. And an alloy or a compound thereof. Among these valve metals, those composed of any one of Al, Nb, Ta and W are preferable.

The dielectric coating is formed, for example, by subjecting the anode body to chemical conversion treatment such as anodic oxidation. That is, the dielectric film is preferably a dielectric oxide film formed by oxidizing the valve metal constituting the anode body. Anodization is performed, for example, by applying a voltage to the anode body in a phosphoric acid solution. The magnitude of the formation voltage at this time is determined by the thickness of the dielectric film and the withstand voltage of the capacitor. Usually, the formation voltage is preferably 1 to 800V, more preferably 1 to 300V, and still more preferably 10 to 100V.

<Solid electrolyte>
The method for forming the solid electrolyte is not particularly limited. For example, a conductive polymer dispersion is impregnated into the capacitor element (that is, the porous body) so as to be located on the surface of the porous body, and then the dispersion liquid is formed. It is formed by removing part or all of the dispersion medium. As an example of the capacitor element mentioned here, for example, a sintered body obtained by sintering valve metal powder is provided with an anode lead terminal, and the sintered body is further formed with a dielectric film by anodic oxidation. Further, there may be mentioned a structure in which an anode foil and a cathode foil in which a valve metal foil is etched and then anodized to form a dielectric film are arranged.

The solid electrolyte of the solid electrolytic capacitor of the present application covers the whole or a part of the dielectric coating. This solid electrolyte is preferably a solid electrolyte layer covering the whole or a part of the dielectric coating. Since the coverage cannot be strictly defined, the coverage was measured by the method described in EIAJ standard RC2361A. That is, after impregnating a conductive polymer dispersion with respect to the capacitance obtained by impregnating the capacitor element with an electrolytic solution (30% sulfuric acid solution), and then removing part or all of the dispersion medium. The ratio with the electrostatic capacity obtained, that is, the capacity appearance rate can be replaced with the coverage.

According to the method for producing a solid electrolytic capacitor of the present application, it is possible to form a conductive solid layer with a high coverage of preferably about 80 to 100%, more preferably 85 to 100%, and still more preferably 88 to 100%. It is. By increasing the coverage, it is possible to provide a solid electrolytic capacitor having high capacitance and low ESR. On the other hand, although there is a report that the repairability of the dielectric film decreases as the coverage increases, it is possible to improve the repairability of the dielectric film by impregnating with an electrolytic solution.

The application amount of the solid electrolyte is not particularly limited, and can be appropriately determined depending on the type of the solid electrolyte and the use of the solid electrolytic capacitor.

(Conductive polymer)
Although it does not specifically limit as a conductive polymer, The organic polymer by which the principal chain is comprised by (pi) conjugated system is preferable. Examples of the organic polymer include polypyrroles, polythiophenes, polyacetylenes, polyphenylenes, polyphenylene vinylenes, polyanilines, polyacenes, polythiophene vinylenes, and copolymers thereof. Of these, polypyrroles, polythiophenes and polyanilines are preferred, and polythiophenes are more preferred. When the conductive polymer has a substituent such as an alkyl group, a carboxylic acid group, a sulfonic acid group, an alkoxyl group, a hydroxyl group, or a cyano group, high conductivity is obtained, which is preferable.

Among these conductive polymers, polypyrrole and poly (N-methylpyrrole) as polypyrroles; polythiophene, poly (3-methylthiophene), poly (3-methoxythiophene), and poly (3,4-ethylene as polythiophenes At least one selected from the group consisting of dioxythiophene) is preferable in terms of conductivity. In particular, poly (3,4-ethylenedioxythiophene) is preferable in that it has particularly high conductivity and is excellent in heat resistance.
The conductive polymer is obtained by polymerizing a monomer corresponding to the structure. Preferable monomers include at least one selected from the group consisting of pyrrole which may have a substituent, aniline which may have a substituent, and thiophene which may have a substituent.

Specific examples of such monomers include pyrrole, N-methylpyrrole, 3-methylpyrrole, 3-ethylpyrrole, 3-n-propylpyrrole, 3-butylpyrrole, 3-octylpyrrole, 3-decylpyrrole, 3 -Dodecylpyrrole, 3,4-dimethylpyrrole, 3,4-dibutylpyrrole, 3-carboxylpyrrole, 3-methyl-4-carboxylpyrrole, 3-methyl-4-carboxyethylpyrrole, 3-methyl-4-carboxybutyl Pyrrole, 3-hydroxypyrrole, 3-methoxypyrrole, 3-ethoxypyrrole, 3-butoxypyrrole, 3-hexyloxypyrrole, 3-methyl-4-hexyloxypyrrole, 3-methyl-4-hexyloxypyrrole;
A thiophene derivative represented by the following formula (I):
Examples include aniline, 2-methylaniline, 3-isobutylaniline, 2-aniline sulfonic acid, and 3-aniline sulfonic acid. These can be used alone or in combination of two or more.

In formula (I), R ¹ and R ² each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 18 carbon atoms, or an optionally substituted carbon group having 1 to 18 carbon atoms. It represents an alkoxy group or an alkylthio group which may having 1 to 18 carbon atoms have a substituent, or, together with R ¹ and R ² are bonded and the carbon atom to which R ¹ and R ² are attached An alicyclic ring having 3 to 10 carbon atoms which may have a substituent, an aromatic ring having 6 to 10 carbon atoms which may have a substituent, and 2 to 10 carbon atoms which may have a substituent. An oxygen atom-containing heterocyclic ring, an optionally substituted sulfur atom-containing heterocyclic ring having 2 to 10 carbon atoms, or an optionally substituted sulfur atom and oxygen atom-containing heterocyclic ring having 2 to 10 carbon atoms May be formed.

Examples of the oxygen atom-containing heterocycle include an oxirane ring, oxetane ring, furan ring, hydrofuran ring, pyran ring, pyrone ring, dioxane ring, and trioxane ring.

Examples of the sulfur atom-containing heterocyclic ring include thiirane ring, thietane ring, thiophene ring, thiane ring, thiopyran ring, thiopyrylium ring, benzothiopyran ring, dithiane ring, dithiolane ring, and trithiane ring.

Examples of the sulfur atom and oxygen atom-containing heterocycle include an oxathiolane ring and an oxathian ring.

It is preferable that a monomer contains the compound represented by the said formula (I) among said compounds. Specific examples of the compound represented by the above formula (I) include thiophene, 3-methylthiophene, 3-ethylthiophene, 3-propylthiophene, 3-butylthiophene, 3-hexylthiophene, 3-heptylthiophene, 3- Octylthiophene, 3-decylthiophene, 3-dodecylthiophene, 3-octadecylthiophene, 3-bromothiophene, 3-chlorothiophene, 3-iodothiophene, 3-cyanothiophene, 3-phenylthiophene, 3,4-dimethylthiophene, 3,4-dibutylthiophene, 3-hydroxythiophene, 3-methoxythiophene, 3-ethoxythiophene, 3-butoxythiophene, 3-hexyloxythiophene, 3-heptyloxythiophene, 3-octyloxythiophene, 3-decyloxy Offene, 3-dodecyloxythiophene, 3-octadecyloxythiophene, 3,4-dihydroxythiophene, 3,4-dimethoxythiophene, 3,4-diethoxythiophene, 3,4-dipropoxythiophene, 3,4-dibutoxy Thiophene, 3,4-dihexyloxythiophene, 3,4-diheptyloxythiophene, 3,4-dioctyloxythiophene, 3,4-didecyloxythiophene, 3,4-didodecyloxythiophene, 3,4-ethylene Dioxythiophene, 3,4-propylenedioxythiophene, 3,4-butylene dioxythiophene, 3-methyl-4-methoxythiophene, 3-methyl-4-ethoxythiophene, 3-carboxythiophene, 3-methyl-4 -Carboxythiophene, 3-methyl- - carboxyethyl thiophene, 3-methyl-4-carboxybutyl thiophene, 3,4-ethyleneoxythiathiophene.
The monomer more preferably contains a compound represented by the following formula (II).

In formula (II), R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms which may have a substituent, or R ³ and R ⁴ are bonded to each other. In addition, each of the carbon atoms to which OR ³ and OR ⁴ are bonded may form an oxygen atom-containing heterocycle having 3 to 6 carbon atoms which may have a substituent.

R ³ and R ⁴ preferably have 3 to 6 carbon atoms which may have a substituent, together with the carbon atoms to which R ³ and R ⁴ are bonded and to which OR ³ and OR ⁴ are bonded. To form an oxygen atom-containing heterocycle. Examples of the oxygen atom-containing heterocycle include an oxirane ring, an oxetane ring, a furan ring, a hydrofuran ring, a pyran ring, a pyrone ring, a dioxane ring, and a trioxane ring, and a dioxane ring is preferable.

The monomer most preferably contains 3,4-ethylenedioxythiophene.

(Polyanion)
The polyanion used in the present invention is a polymer having an anionic group. Examples of the anionic group include a group consisting of a sulfonic acid or a salt thereof, a group consisting of a phosphoric acid or a salt thereof, a monosubstituted phosphate group, a group consisting of a carboxylic acid or a salt thereof, a monosubstituted sulfate group. Among these, a strongly acidic group is preferable, a group consisting of sulfonic acid or a salt thereof, a group consisting of phosphoric acid or a salt thereof is more preferable, and a group consisting of sulfonic acid or a salt thereof is most preferable. The anionic group may be directly bonded to the polymer main chain or may be bonded to the side chain. When an anionic group is bonded to the side chain, the doping effect is more remarkably achieved. Therefore, the anionic group is preferably bonded to the end of the side chain.

The polyanion may have a substituent other than the anionic group. Examples of the substituent include alkyl group, hydroxy group, alkoxy group, phenol group, cyano group, phenyl group, hydroxyphenyl group, ester group, halogeno group, alkenyl group, imide group, amide group, amino group, oxycarbonyl group, A carbonyl group etc. are mentioned. Among these, an alkyl group, a hydroxy group, a cyano group, a phenol group, and an oxycarbonyl group are preferable, and an alkyl group, a hydroxy group, and a cyano group are more preferable. The substituent may be directly bonded to the polymer main chain or may be bonded to the side chain. When the substituent is bonded to the side chain, the substituent is preferably bonded to the end of the side chain in order to perform each function of the substituent.

The alkyl group that can be substituted in the polyanion can be expected to increase the solubility and dispersibility in the dispersion medium, the compatibility and dispersibility with the conjugated conductive polymer, and the like. Examples of the alkyl group include a chain alkyl group such as methyl group, ethyl group, propyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, octyl group, decyl group and dodecyl group; cyclopropyl group, Examples thereof include cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group. In consideration of solubility in a dispersion medium, dispersibility in a conjugated conductive polymer, steric hindrance, and the like, an alkyl group having 1 to 12 carbon atoms is more preferable.

The hydroxy group that can be substituted in the polyanion facilitates the formation of hydrogen bonds with other hydrogen atoms, and has high solubility in dispersion media, high compatibility with conjugated conductive polymers, dispersibility, and adhesion. Can be expected. The hydroxy group is preferably bonded to the terminal of an alkyl group having 1 to 6 carbon atoms bonded to the polymer main chain.

The cyano group and hydroxyphenyl group that can be substituted in the polyanion can be expected to have an effect of increasing the compatibility with the conjugated conductive polymer, the solubility in the dispersion medium, and the heat resistance. The cyano group is bonded directly to the polymer main chain, bonded to the terminal of the alkyl group having 1 to 7 carbon atoms bonded to the polymer main chain, or terminal of the alkenyl group having 2 to 7 carbon atoms bonded to the polymer main chain. Those bonded to are preferred.

The oxycarbonyl group that can be substituted in the polyanion is preferably an alkyloxycarbonyl group, an aryloxycarbonyl group, or an alkyloxycarbonyl group or an aryloxycarbonyl group having another functional group directly bonded to the polymer main chain.

The polymer main chain of the polyanion is not particularly limited. Examples of the polymer main chain include polyalkylene, polyimide, polyamide, and polyester. Of these, polyalkylene is preferable from the viewpoint of synthesis and availability.

Polyalkylene is a polymer composed of repeating units of ethylenically unsaturated monomers. The polyalkylene may have a carbon-carbon double bond in the main chain. Examples of polyalkylene include polyethylene, polypropylene, polybutene, polypentene, polyhexene, polyvinyl alcohol, polyvinylphenol, poly (3,3,3-trifluoropropylene), polyacrylonitrile, polyacrylate, polymethacrylate, polystyrene, polybutadiene, poly And isoprene.

Examples of polyimides include pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, 2,2,3,3-tetracarboxydiphenyl ether dianhydride, 2,2- [4,4 Examples include those obtained by polycondensation reaction of acid anhydrides such as' -di (dicarboxyphenyloxy) phenyl] propane dianhydride and diamines such as oxydianiline, paraphenylenediamine, metaphenylenediamine, and benzophenonediamine. .

Polyamide includes polyamide 6, polyamide 6,6, polyamide 6,10 and the like.

Examples of polyester include polyethylene terephthalate and polybutylene terephthalate.

Specific examples of the polymer having a sulfonic acid group suitably used as a polyanion include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic acid ethyl sulfonic acid, polyacrylic acid butyl sulfonic acid, and poly (2-acrylamide). -2-methylpropanesulfonic acid) and polyisoprenesulfonic acid. These may be homopolymers or two or more types of copolymers. Among these, polystyrene sulfonic acid, polyisoprene sulfonic acid, polyacrylic acid ethyl sulfonic acid, and polyacrylic acid butyl sulfonic acid are preferable. Polyanions, especially polymers with sulfonic acid groups, can mitigate the thermal decomposition of conjugated conductive polymers and improve the dispersibility of the monomers in the dispersion medium to obtain conjugated conductive polymers. And function as a dopant for the conjugated conductive polymer.

The polyanion used in the present invention has a weight average molecular weight of preferably 1,000 to 1,000,000, more preferably 5,000 to 300,000, still more preferably 10,000 to 300,000, and still more preferably 150,000 to 300,000. When the weight average molecular weight is within this range, the solubility of the polyanion in the dispersion medium and the compatibility between the polyanion and the conjugated conductive polymer are improved. A weight average molecular weight is measured as a polystyrene conversion molecular weight using gel permeation chromatography.

The polyanion may have the above properties selected from commercially available products, or may be obtained by synthesis by a known method. Examples of the method for synthesizing polyanions include the method described in Houben-Weyl, “Methoden der organischen Chemie” Vol. E20, Makromolekulare Stoffe, No. 2 (1987) p1141- Is mentioned.

The amount of the polyanion contained in the dispersion is preferably from 0.25 to 10 mol, more preferably from 0.1 to 10 mol, based on 1 mol of the monomer for obtaining the conductive polymer. The amount is 8 to 8 mol, more preferably 0.8 to 5 mol. The mass of the polyanion with respect to 100 parts by mass of the conductive polymer is preferably 10 to 10000 parts by mass, more preferably 50 to 5000 parts by mass, and still more preferably 100 to 1000 parts by mass. When the amount of the polyanion is not more than the upper limit value, the conductivity of the solid electrolyte layer formed from the dispersion tends to be improved. When the amount of the polyanion is not less than the lower limit value, in the dispersion of the conductive polymer. There is a tendency for the dispersibility of to improve.

(Dispersion medium)
The dispersion medium used for this invention will not be specifically limited if a conductive polymer and the polyanion doped to it can be disperse | distributed. As a dispersion medium, for example, water;
Amides such as N-vinylpyrrolidone, hexamethylphosphortriamide, N-vinylformamide, N-vinylacetamide;
Phenols such as cresol, phenol, xylenol;
Dipropylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, diglycerin, isoprene glycol, butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl Polyhydric alcohols such as glycols;
Carbonate compounds such as ethylene carbonate and propylene carbonate; ethers such as dioxane, diethyl ether, propylene glycol dialkyl ether, polyethylene glycol dialkyl ether and polypropylene glycol dialkyl ether;
Heterocyclic compounds such as 3-methyl-2-oxazolidinone; nitriles such as acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, and benzonitrile.

These dispersion media can be used singly or in combination of two or more. Of these, a dispersion medium containing 1 to 99% by mass of water is preferably used, more preferably 50 to 99% by mass of water, and even more preferably water alone.

The amount of the dispersion medium is preferably 1 to 10000 parts by weight, more preferably 50 to 9000 parts by weight, still more preferably 100 to 8000 parts by weight, and still more preferably 100 parts by weight of the total of the conductive polymer and the polyanion. The amount is preferably 1000 to 8000 parts by weight, and more preferably 3000 to 7000 parts by weight. There exists a tendency for the viscosity of a dispersion liquid to fall that the usage-amount of a dispersion medium is more than a lower limit. When the amount of the dispersion medium used is not more than the upper limit value, it is convenient when forming the solid electrolyte layer, for example, the operation time for removing the dispersion medium from the dispersion liquid can be shortened.

(Additive)
The dispersion may contain an additive as necessary. The additive is not particularly limited as long as it can be mixed with the conductive polymer and the polyanion. Examples thereof include water-soluble polymer compounds, water-dispersible compounds, alkaline compounds, surfactants, antifoaming agents, coupling agents, antioxidants, and electrical conductivity improvers.

The water-soluble polymer compound is a water-soluble polymer having a cationic group or a nonionic group in the main chain or side chain of the polymer. Specific examples of the water-soluble polymer compound include, for example, polyoxyalkylene, water-soluble polyurethane, water-soluble polyester, water-soluble polyamide, water-soluble polyimide, water-soluble polyacryl, water-soluble polyacrylamide, polyvinyl alcohol, polyacrylic acid and the like. Is mentioned. Of these, polyoxyalkylene is preferred.

Specific examples of polyoxyalkylene include diethylene glycol, triethylene glycol, oligopolyethylene glycol, triethylene glycol monochlorohydrin, diethylene glycol monochlorohydrin, oligoethylene glycol monochlorohydrin, triethylene glycol monobromohydrin, diethylene glycol monobromhydrin, Oligoethylene glycol monobromohydrin, polyethylene glycol, glycidyl ethers, polyethylene glycol glycidyl ethers, polyethylene oxide, triethylene glycol / dimethyl ether, tetraethylene glycol / dimethyl ether, diethylene glycol / dimethyl ether, diethylene glycol / diethyl ether / diethylene glycol Dibutyl ether, dipropylene glycol, tripropylene glycol, polypropylene glycol, polypropylene dioxide, polyoxyethylene alkyl ethers, polyoxyethylene glycerol fatty acid esters, polyoxyethylene fatty acid amides.

A water-dispersible compound is a compound in which a part of a low hydrophilic compound is substituted with a highly hydrophilic functional group, or a compound having a highly hydrophilic functional group adsorbed around a low hydrophilic compound (E.g., an emulsion) that is dispersed without being precipitated in water. Specific examples include polyester, polyurethane, acrylic resin, silicone resin, and emulsions of these polymers. The water-soluble polymer compound and the water-dispersible compound can be used singly or in combination of two or more. When a water-soluble polymer compound and a water-dispersible compound are added, the dispersion containing the conductive polymer composition can be thickened or the coating performance can be improved.

The amount of the water-soluble polymer compound and the water-dispersible compound is preferably 1 to 4000 parts by mass, more preferably 50 to 2000 parts by mass with respect to a total of 100 parts by mass of the conjugated conductive polymer and the polyanion. . When the amount of the water-soluble polymer compound and the water-dispersible compound is at least the lower limit value, the conductivity tends to be high, and the ESR characteristics of the solid electrolytic capacitor tend to be improved.

Alkaline compounds are used for the purpose of adjusting the pH of the dispersion. For example, the pH is preferably 3 to 13 in order to prevent corrosion of metals and metal oxides used in the solid electrolytic capacitor. More preferably, the pH is adjusted to 4 to 7, and still more preferably adjusted to pH 4 to 6. When the pH is less than 3, the progress of corrosion can be suppressed even if aluminum is used. Further, when the pH is 13 or less, it is possible to prevent undoping of the polyanion doped in the conductive polymer.

As the alkaline compound, known inorganic alkaline compounds and organic alkaline compounds can be used. Examples of the inorganic alkaline compound include ammonia, sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia and the like. Examples of the organic alkaline compound include aromatic amines, aliphatic amines, and alkali metal alkoxides.

Among aromatic amines, nitrogen-containing heteroaryl ring compounds are preferred. The nitrogen-containing heteroaryl ring compound is a nitrogen-containing heterocyclic compound that exhibits aromaticity. In aromatic amines, the nitrogen atom contained in the heterocycle has a conjugated relationship with other atoms.

Nitrogen-containing heteroaryl ring compounds include pyridines, imidazoles, pyrimidines, pyrazines, triazines and the like. Of these, pyridines, imidazoles, and pyrimidines are preferable from the viewpoint of solvent solubility and the like.

Examples of the aliphatic amine include ethylamine, n-octylamine, diethylamine, diisobutylamine, methylethylamine, trimethylamine, triethylamine, allylamine, 2-ethylaminoethanol, 2,2′-iminodiethanol, N-ethylethylenediamine, and the like. It is done.

Examples of the alkali metal alkoxide include sodium alkoxide such as sodium methoxide and sodium ethoxide, potassium alkoxide and calcium alkoxide.

Surfactants include anionic surfactants such as carboxylates, sulfonates, sulfates and phosphates; cationic surfactants such as amine salts and quaternary ammonium salts; carboxybetaines and aminocarboxylic acids Examples include amphoteric surfactants such as salts and imidazolium betaines; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene glycerin fatty acid esters, ethylene glycol fatty acid esters, and polyoxyethylene fatty acid amides.

Examples of the antifoaming agent include silicone resin, polydimethylsiloxane, and silicone resin.

Examples of antioxidants include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, sugars, and vitamins.

The electrical conductivity improver is not particularly limited as long as it increases the electrical conductivity of the solid electrolyte layer obtained from the dispersion. Examples of the electrical conductivity improver include compounds containing an ether bond such as tetrahydrofuran; compounds containing a lactone group such as γ-butyrolactone and γ-valerolactone; caprolactam, N-methylcaprolactam, N, N-dimethylacetamide, N -Compounds containing amide or lactam groups such as methylacetamide, N, N-dimethylformamide, N-methylformamide, N-methylformanilide, N-methylpyrrolidone, N-octylpyrrolidone, pyrrolidone; tetramethylenesulfone, dimethylsulfoxide, etc. Sulfone compounds or sulfoxide compounds; sugars or sugar derivatives such as sucrose, glucose, fructose and lactose; sugar alcohols such as sorbitol and mannitol; succinimide and maleimi And imides such as 2-furan carboxylic acid, furan derivatives such as 3-furan carboxylic acid; dialcohols such as ethylene glycol, propylene glycol, glycerol, diethylene glycol, triethylene glycol, and polyalcohols. Of these, tetrahydrofuran, N-methylformamide, N-methylpyrrolidone, ethylene glycol, propylene glycol, dimethyl sulfoxide, and sorbitol are particularly preferable from the viewpoint of improving electrical conductivity. An electrical conductivity improver can be used individually by 1 type or in combination of 2 or more types.
(Dispersion)
The dispersion used in the present invention contains a conductive polymer, a polyanion, and a dispersion medium. The dispersion may contain the aforementioned additives. The types and contents of these conductive polymers, polyanions, dispersion media, and additives are as described above.
The solid concentration of the dispersion is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1 to 5% by mass.
The total amount of the conductive polymer and the polyanion in the solid content of the dispersion is preferably 20 to 100% by mass, more preferably 40 to 90% by mass, and still more preferably 50 to 90% by mass.

(Manufacture of dispersion)
The dispersion of the present invention is produced by polymerizing the monomer in the dispersion medium, and includes a step of adding the polyanion during the polymerization.

In order to polymerize the monomer in a dispersion medium, first, the monomer and, if necessary, an additive are added to the dispersion medium and dissolved, emulsified or dispersed, and the monomer solution, emulsion or A dispersion (hereinafter sometimes referred to as a monomer liquid) is obtained. The monomer solution may be prepared by a powerful stirring device such as a homogenizer, but it is preferably by ultrasonic irradiation. The ultrasonic irradiation energy is not particularly limited as long as a uniform monomer liquid can be obtained. The ultrasonic irradiation is preferably performed for 0.1 to 2 hours / L at a power consumption of 5 to 500 W / L. The power consumption is more preferably 1 to 200 W / L, still more preferably 20 to 100 W / L. The irradiation time is more preferably 0.1 to 4 hours / L, still more preferably 0.5 to 2 hours / L.

From the viewpoint of suppressing aggregation of the conductive polymer generated during the polymerization, the monomer liquid before the start of polymerization preferably contains a part of the polyanion finally contained in the dispersion. The polyanion can be contained in the monomer liquid by mixing with the monomer and dissolving, emulsifying or dispersing the resulting mixture in a dispersion medium. The amount of the polyanion to be contained in the monomer liquid before the start of polymerization is preferably 0 to 99% by mass, more preferably 10 to 90% by mass, still more preferably 20 to 80% by mass, based on the total amount of polyanions in the dispersion. More preferably, it is ˜70% by mass.

For example, in the case of producing a dispersion containing polypyrroles or polythiophenes as a conductive polymer, the polymerization of the monomer is started by bringing the monomer to a predetermined temperature in the presence of an oxidizing agent. As oxidizing agents, peroxodisulfates such as ammonium peroxynonisulfate, sodium peroxodisulfate, and potassium peroxodisulfate; metal halogen compounds such as boron trifluoride; And transition metal compounds such as cupric chloride; metal oxides such as silver oxide and cesium oxide; peroxides such as hydrogen peroxide and ozone; organic peroxides such as benzoyl peroxide; oxygen and the like. Of these, peroxodisulfate is preferred.

In the present invention, a polyanion is added to the polymerization reaction solution during the polymerization. By this method, it is possible to obtain a conductive polymer having excellent conductivity without excessively increasing the viscosity during the polymerization, so that it is possible to obtain a dispersion having excellent impregnation and coating properties for the porous body. In addition, a solid electrolyte layer having excellent conductivity can be formed. In addition, since the polyanion is reliably doped into the conductive polymer having a regularly long main chain, a solid electrolytic capacitor having excellent high frequency characteristics can be manufactured.
The amount of the polyanion added to the dispersion medium during the polymerization (after the start of polymerization) is preferably 1 to 99% by mass, more preferably 20 to 80% by mass, and more preferably 20 to 60% by mass of the total amount of polyanions contained in the dispersion medium. More preferably, 30 to 50% by mass is even more preferable.

The addition of the polyanion is preferably performed continuously or intermittently in order to suppress a rapid increase in the polyanion concentration. Moreover, in order to mix the polyanion added to the polymerization reaction solution uniformly, it is preferable to add it as a polyanion solution. *

It is preferable to use as the solvent a solution containing a dispersion medium used in the polymerization reaction solution. The rate of addition of the polyanion varies depending on the scale of the reaction apparatus, and thus cannot be generally determined, but is usually 1 to 1000 parts by mass / hour, more preferably 5 to 100 parts by mass with respect to 100 parts by mass of the monomer. Part / hour, more preferably 10 to 50 parts by weight / hour.

The temperature during polymerization is usually 5 to 80 ° C., more preferably 10 to 50 ° C., and further preferably 12 to 35 ° C. When the temperature during polymerization is within this range, polymerization can be carried out at an appropriate reaction rate, increase in viscosity can be suppressed, and production of a dispersion containing a conductive polymer composition can be carried out stably and economically. And the conductivity of the resulting conductive polymer tends to be high. The temperature at the time of superposition | polymerization can be managed by using a well-known heater and a cooler. Moreover, you may superpose | polymerize, changing temperature within the said range as needed.

When producing the dispersion, it is preferable to disperse the produced conductive polymer during the polymerization. This dispersion treatment can be performed by a powerful stirring device such as a homogenizer, but is preferably performed by ultrasonic irradiation. By this dispersion treatment, aggregation of the conductive polymer having a long main chain can be suppressed. The ultrasonic irradiation energy is not particularly limited as long as aggregation of the conductive polymer can be suppressed. The ultrasonic irradiation is preferably performed until the end of the reaction with the above-described power consumption.

(Viscosity of dispersion)
[Method of manufacturing solid electrolytic capacitor]
The solid electrolytic capacitor of the present invention includes a step of applying a dispersion containing a conductive polymer, a polyanion, and a dispersion medium to the surface of the porous body, and removing a part or all of the dispersion medium to obtain a solid electrolyte. And a step of forming a layer.

(Dispersion application)
The method for applying the dispersion to the surface of the porous body is not particularly limited, and a method of impregnating the porous body with the dispersion or a method of applying the dispersion to the surface of the porous body may be used. it can.
The dispersion can be applied once or twice or more.

(Removal of dispersion medium)
The removal of the dispersion medium is preferably carried out by heat treatment because it is efficient. The heating condition is preferably set in a range in which the conductive polymer does not undergo oxidative deterioration, and can be appropriately determined depending on the boiling point and volatility of the dispersion medium. Usually, the heating temperature is 20 to 300 ° C, preferably 50 to 200 ° C, more preferably 80 to 150 ° C. The heat treatment time is preferably 1 second to 10 hours, more preferably 5 seconds to 2 hours, still more preferably 10 minutes to 1 hour.

For the heat treatment, a known means used for producing a solid electrolytic capacitor can be used, and for example, a hot plate, an oven, a hot air dryer or the like can be used. The heat treatment may be performed in the air, or may be performed under reduced pressure in order to quickly remove the dispersion medium.

When the step of applying the dispersion medium is repeated twice or more, heat treatment may be performed for each application, and the dispersion medium may be removed, or after applying a plurality of times, the dispersion medium is finally removed. May be.

(Other processes)
The manufacturing method of the solid electrolytic capacitor of this invention can include the well-known process performed when manufacturing a solid electrolytic capacitor besides the above-mentioned process. For example, an arbitrary electrolytic solution can be further impregnated in the voids of the solid electrolyte layer formed by removing part or all of the dispersion medium.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples.

(Manufacture of dispersion liquid containing conductive polymer)
(Production Example 1)
733.3 g of ion-exchanged water, sodium polystyrene sulfonate (manufactured by Tosoh Organic Chemical Co., Ltd., trade name Polynas (PS-50), solid content concentration: 20 mass%, weight average molecular weight: about 2.3 × 10 ⁵ , below 81.5 g (also referred to as PSS-Na) was dissolved in water to prepare a 2% by weight aqueous solution of sodium polystyrenesulfonate.

4288 parts by weight of ion-exchanged water, 7498 parts by weight of a 2% by weight aqueous solution of sodium polystyrene sulfonate, and 420 parts by weight of a 2% by weight aqueous solution of iron (III) p-toluenesulfonate hexahydrate (manufactured by Sigma-Aldrich Co.) And mixed. To this solution, 100 parts by mass of 3,4-ethylenedioxythiophene (manufactured by Tokyo Chemical Industry Co., Ltd.) was added and mixed while irradiating ultrasonic waves at 27 ° C.

To the obtained mixed solution, 210 parts by mass of sodium peroxodisulfate (manufactured by Kanto Chemical Co., Inc.) was added while stirring with a stirring blade and ultrasonic irradiation at 27 ° C. to initiate the polymerization reaction. Next, 4999 parts by mass of a 2% by weight aqueous sodium polystyrenesulfonate solution was added dropwise over 4 hours. Then, it was made to react, stirring with a stirring blade and ultrasonic irradiation for 4 hours at 27 degreeC. Note that the power consumption of ultrasonic irradiation is 300 W (50 W / L), and the irradiation time is 8 hours (1.3 hours / L).

After completion of the reaction, 1100 parts by mass of cation exchange resin and 1100 parts by mass of anion exchange resin are added to the resulting reaction solution, and the reaction solution is stirred for 12 hours, thereby removing unreacted monomers, oxidizing agent and oxidation catalyst. Adsorbed on an ion exchange resin. The ion exchange resin was filtered off to obtain a dispersion containing a conductive polymer composition containing poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid doped therein. This dispersion had a solid content concentration of 2.0% by mass, a viscosity of 150 mPa · s, and a pH of 1.9.

Next, while stirring 100 parts by mass of the dispersion containing the conductive polymer composition, ammonia water was added, and further 10 parts by mass of ethylene glycol was added to obtain dispersion 1. The pH of this dispersion was 4.5.

(Production Example 2)
The same method as in dispersion 1 except that the 2% by weight aqueous solution of sodium polystyrenesulfonate was changed to a 2% by weight aqueous solution of polystyrenesulfonic acid prepared by diluting a 20% by weight aqueous solution of polystyrenesulfonic acid manufactured by Wako Pure Chemical Industries, Ltd. Dispersion 2 containing a conductive polymer composition was produced. The pH of this dispersion was 4.5.
(Production Example 3)
Dispersion 3 containing the conductive polymer composition was produced in the same manner as dispersion 1, except that the polymerization reaction was performed at 40 ° C. The pH of this dispersion was 4.5.
(Production Example 4)
Dispersion 4 containing the conductive polymer composition was produced in the same manner as dispersion 1, except that the polymerization reaction was carried out at 15 ° C. The pH of this dispersion was 4.5.

(Comparative Production Example 1)
A conductive polymer composition was prepared in the same manner as in the dispersion 1 except that the reaction was continued by stirring with a stirring blade and ultrasonic irradiation at 27 ° C. for 10 hours without adding polystyrene sulfonic acid during the reaction. A comparative dispersion 1 containing was obtained. The pH of this comparative dispersion was 4.5.
(Comparative Production Example 2)
A conductive polymer composition was prepared in the same manner as in the dispersion 2 except that the reaction was continued by stirring with a stirring blade and ultrasonic irradiation at 27 ° C. for 10 hours without adding polystyrene sulfonic acid during the reaction. A comparative dispersion 2 containing was obtained. The pH of this comparative dispersion was 4.5.
(Comparative Production Example 3)
Comparative dispersion 3 containing a conductive polymer composition was produced in the same manner as comparative dispersion 1, except that the polymerization reaction was performed at 40 ° C. The pH of this comparative dispersion was 4.5.
(Comparative Production Example 4)
Comparative dispersion 4 containing a conductive polymer composition was produced in the same manner as comparative dispersion 1, except that the polymerization reaction was carried out at 15 ° C. The pH of this comparative dispersion was 4.5.

(Examples 1 to 4 and Comparative Examples 1 to 4)
(Formation of porous material)
As a porous body used for a solid electrolytic capacitor, a niobium powder for a capacitor is used to form a dielectric film made of niobium pentoxide on the surface of the anode body by the method described in Production Example 1 of JP2011-77257A. A porous body was produced.
That is, 20 mg of niobium powder for capacitors having a nominal CV product of 150,000 μF · V / g was molded together with a niobium wire to produce a molded body of 2 mm × 2 mm × 1.4 mm. The niobium wire was planted on a 2 mm × 1.4 mm surface. The niobium wire is an anode lead wire. This molded body was fired at 1215 ° C. for 30 minutes under a reduced pressure of 4 × 10 ⁻³ Pa to be sintered. The obtained sintered body, that is, the anode body was immersed in a 1% by mass phosphoric acid aqueous solution at 80 ° C. and subjected to chemical conversion treatment at 30 V for 2 hours. A dielectric layer containing niobium pentoxide was formed on the surface of the anode body.

The capacitance of this porous material in 30% sulfuric acid was measured by the method described in “EIAJ Standard RC2361A” (revised in February 2000), and was 80 μF.

(Impregnation of dispersion)
The porous body was impregnated with the dispersion shown in Table 2 for 1 minute in an atmosphere at 25 ° C., and then dried with a hot air dryer at 110 ° C. for 30 minutes. Next, carbon paste (Tanaka Kikinzoku Co., Ltd. product name: TC-8260) is applied and dried so as to cover the entire surface of the porous body so as not to contact the anode lead terminal. Noble Metal Co., Ltd. product name: TS-8205) was applied and dried so as to cover the entire porous body so as not to contact the anode lead terminal.

Table 1 shows the measurement results of the capacitance at 120 Hz and the equivalent series resistance (ESR) at 100 kHz of the obtained solid electrolytic capacitor.

As shown in Table 1, in Example 1 and Comparative Example 1, the total amount of polyanions used for producing the dispersion is the same, but in Example 1, a part of the polyanions was added to the dispersion medium during the polymerization. In contrast, in Comparative Example 1, all of the polyanion is added to the dispersion medium before polymerization. In Example 1 and Comparative Example 1, the same operation is performed except that the timing of adding the polyanion to the dispersion medium is changed. Then, Example 1 has a larger capacitance and a smaller equivalent series resistance than Comparative Example 1. Similarly, in Examples 2 to 4 and Comparative Examples 2 to 4, the same operation is performed except that the timing of adding the polyanion to the dispersion medium is changed. In Examples 2 to 4 in which the polyanion was added during the polymerization, the capacitance was larger and the equivalent series resistance was smaller than those in Comparative Examples 2 to 4 in which the polyanion was not added during the polymerization. ing.
Table 1 shows that the solid electrolytic capacitor of the present invention has a large capacitance and a small equivalent series resistance.

Claims

A solid electrolytic capacitor having a porous body having at least an anode body made of a valve metal and a dielectric coating formed on the surface of the anode body, and a solid electrolyte formed on the surface of the porous body,
The solid electrolyte is formed by removing a part or all of a dispersion medium from a dispersion liquid containing a conductive polymer, a polyanion and a dispersion medium.
The dispersion liquid is produced by polymerizing a monomer in the dispersion medium, and includes a step of adding a polyanion in the course of the polymerization.
The solid electrolytic capacitor according to claim 1, wherein the monomer is a thiophene derivative represented by the following formula (I).

(In Formula (I), R 1 and R 2 each independently represents a hydrogen atom, an optionally substituted alkyl group having 1 to 18 carbon atoms, or an optionally substituted carbon group having 1 to 18 represents an alkoxy group having 18 or an optionally substituted alkylthio group having 1 to 18 carbon atoms, or R 1 and R 2 are a combination of R 1 and R 2 and R 1 and R 2 being Along with each carbon atom to be bonded, an alicyclic ring having 3 to 10 carbon atoms which may have a substituent, an aromatic ring having 6 to 10 carbon atoms which may have a substituent, and a substituent A C2-C10 oxygen atom-containing heterocycle, a C2-C10 sulfur atom-containing heterocycle which may have a substituent, or a C2-C10 which may have a substituent Represents a heterocycle containing a sulfur atom and an oxygen atom.)
The solid electrolytic capacitor according to claim 1 or 2, wherein the polyanion is a polymer having a group consisting of sulfonic acid or a salt thereof.
4. The solid electrolytic capacitor according to claim 1, wherein ultrasonic irradiation is performed in the course of the polymerization.
Applying a dispersion containing a conductive polymer, a polyanion, and a dispersion medium to the surface of a porous body having at least an anode body made of a valve metal and a dielectric coating formed on the surface of the anode body;
A method of producing a solid electrolytic capacitor comprising a step of forming a solid electrolyte by removing a part or all of the dispersion medium,
The dispersion is produced by polymerizing a monomer in the dispersion medium, and includes a step of adding a polyanion in the course of the polymerization. .
The solid electrolytic capacitor according to claim 5, wherein the dispersion includes a step of initiating polymerization of the monomer in the presence of an oxidizing agent, and a step of adding a polyanion during the polymerization. Manufacturing method.
The method for producing a solid electrolytic capacitor according to claim 5 or 6, wherein 1 to 100% by mass of the total amount of the polyanion is added to the dispersion medium during the polymerization of the monomer.
The method for producing a solid electrolytic capacitor according to any one of claims 5 to 7, wherein 20 to 80% by mass of the total amount of the polyanion is added to the dispersion medium during the polymerization of the monomer.
The method for producing a solid electrolytic capacitor according to any one of claims 5 to 8, wherein 0 to 99 mass% of the total amount of the polyanion is added to the dispersion medium before the polymerization of the monomer is started.
The method for producing a solid electrolytic capacitor according to any one of claims 5 to 9, wherein a total amount of the polyanion of 20 to 80% by mass is added to the dispersion medium before the polymerization of the monomer is started.
The method for producing a solid electrolytic capacitor according to any one of claims 5 to 10, wherein the polyanion is continuously or intermittently added to the dispersion medium during polymerization of the monomer in the dispersion medium. .
The rate of addition of the polyanion to the dispersion medium during the polymerization of the monomer in the dispersion medium is 1 to 1000 parts by mass / hour with respect to 100 parts by mass of the monomer in the dispersion medium. The method for producing a solid electrolytic capacitor according to any one of claims 5 to 11, wherein:
The rate of addition of the polyanion to the dispersion medium during the polymerization of the monomer in the dispersion medium is 10 to 100 parts by mass / hour with respect to 100 parts by mass of the monomer in the dispersion medium. The method for producing a solid electrolytic capacitor according to any one of claims 5 to 12.
The method for producing a solid electrolytic capacitor according to any one of claims 5 to 13, wherein the temperature during polymerization is 5 to 80 ° C.
15. The method for producing a solid electrolytic capacitor according to claim 5, wherein ultrasonic irradiation is performed in the course of the polymerization.
16. The method for producing a solid electrolytic capacitor according to claim 5, wherein stirring with a stirring blade and ultrasonic irradiation are performed during the polymerization.