JP2015048370A - Conductive composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive material which impregnates into the inside of a dielectric oxide film of a capacitor and has conductive performance that endures a heating treatment in a capacitor production process; a method for producing the same; a solid electrolytic capacitor using the conductive material; and a method for producing the solid electrolytic capacitor.SOLUTION: Provided is a conductive composite material which contains a conductive polymer (A) having an acidic group and a polymer (B) obtained by polymerizing a thiophene derivative, and satisfies the following condition (I). Condition (I): among one or more peaks obtained by measuring a particle size distribution by a dynamic light scattering method using a conductive composite material solution containing 1 mass% of the conductive composite material, a volume average particle size of a minimum particle distribution including a peak with a minimum particle size is 25 nm or less.

Description

  The present invention relates to a conductive composite material, a manufacturing method thereof, a solid electrolytic capacitor, and a manufacturing method thereof.

In recent years, a conductive polymer has been solidified on a dielectric oxide film formed on the surface of an anode body (film-forming metal) made of a porous metal body having a valve action such as aluminum, niobium, tantalum, titanium, and magnesium. A solid electrolytic capacitor in which a solid electrolyte layer used as an electrolyte and a cathode body are sequentially formed has been developed.
Such a solid electrolytic capacitor has a conductivity 10 to 100 times higher than that of a conventional solid electrolytic capacitor using manganese dioxide as a solid electrolyte, and greatly reduces ESR (equivalent series resistance). Therefore, it is expected to be applied to various uses such as high frequency noise absorption of small electronic devices.

  As a method for forming a solid electrolyte layer on a dielectric oxide film, a chemical oxidative polymerization method or an electrolytic polymerization method is generally used. As a method of forming a solid electrolyte layer without performing chemical oxidative polymerization or electrolytic polymerization on a dielectric oxide film, there is a polymer dipping method.

The polymer immersion method is a method in which a monomer is polymerized with an oxidizing agent in advance to form a polymer (conductive polymer), and a dielectric oxide film is immersed in a dispersion containing the polymer and dried to form a solid electrolyte layer. . Therefore, it is not necessary to perform the polymerization reaction on the dielectric oxide film unlike the chemical oxidative polymerization method or the electrolytic polymerization method, so that the impurities are not mixed into the solid electrolyte layer and the manufacturing process is relatively easy to control.
For example, Patent Document 1 discloses a method for forming a solid electrolyte layer by a polymer dipping method. Specifically, a solid electrolyte is formed using a conductive polymer dispersion obtained by mixing EDOT and an oxidizing agent, polystyrene sulfonic acid and dimethyl sulfoxide, and adding EDOT and an oxidizing agent.

However, in the case of the polymer immersion method, it is difficult for the dispersion liquid of the conductive polymer to be impregnated to the inside of the dielectric oxide film, and as a result, the solid electrolyte layer is hardly formed inside the micropores of the dielectric oxide film, and only the surface layer is formed. Therefore, there is a problem that the capacity expression rate of the obtained solid electrolytic capacitor is lowered.
In recent years, solid electrolytic capacitors have been reduced in size, weight, and capacity, and the inside of the dielectric oxide film of the capacitor has become fine and complicated. As a method of forming a solid electrolyte inside the dielectric oxide film, there is a method of impregnating the polymer solution inside the dielectric oxide film by using a polymer solution in which the average particle diameter of a specific soluble aniline-based conductive polymer is defined. It has been proposed (Patent Document 2).
However, the conductive performance that can withstand the heat treatment in the capacitor manufacturing process is insufficient.

JP 2013-12216 A WO13 / 024532

  The present invention has been made in view of the above circumstances, a conductive material having a conductive performance that is immersed in the dielectric oxide film of the capacitor and can withstand heat treatment in the capacitor manufacturing process, and a method for manufacturing the conductive material. An object of the present invention is to provide a solid electrolytic capacitor using the material and a method of manufacturing the solid electrolytic capacitor.

  The conductive material of the present invention is a conductive composite material that includes a conductive polymer (A) having an acidic group and a polymer (B) obtained by polymerizing a thiophene derivative and satisfies the following condition (I).

  Condition (I): Among one or more peaks obtained by measuring the particle distribution by a dynamic light scattering method using a conductive material solution containing 1% by mass of a conductive material, the peak having the smallest particle diameter The volume average particle diameter of the minimum particle distribution to be included is 25 nm or less.

  Here, it is preferable that the conductive polymer (A) having the acidic group has a repeating unit represented by the following general formula (1).

In formula (1), R ^{1 to} R ⁴ each independently represent —H, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkoxy group having 1 to 24 carbon atoms, or an acidic group. Or its salt, a hydroxyl group, a nitro group, -F, -Cl, -Br or -I, and at least one of R ^{1 to} R ⁴ is an acidic group or a salt thereof. Here, the acidic group is a sulfonic acid or a carboxy group. )
Furthermore, the conductive composite material further includes a compound having an OH group.

  In addition, the method for producing a conductive material described above is characterized in that the thiophene derivative is polymerized in the presence of the conductive polymer (A) having the acidic group to satisfy the condition (I).

  The solid electrolytic capacitor of the present invention is characterized by having a solid electrolyte layer using the conductive composite material on a dielectric oxide film formed on the surface of a film-forming metal.

  Moreover, the method for producing a solid electrolytic capacitor of the present invention includes a step of forming a solid electrolyte layer on the dielectric oxide film formed on the surface of the film-forming metal using the conductive composite material. To do.

  The conductive composite material of the present invention has a conductive performance that is immersed in the dielectric oxide film of the capacitor and can withstand heat treatment in the capacitor manufacturing process.

  In addition, according to the method for manufacturing a conductive composite material of the present invention, a conductive material that has a conductive performance that is immersed in the dielectric oxide film of the capacitor and can withstand heat treatment in the capacitor manufacturing process can be easily manufactured. .

It is sectional drawing which shows an example of the solid electrolytic capacitor of this invention typically. It is a perspective view which shows typically another example of the solid electrolytic capacitor of this invention. It is a figure which shows typically particle distribution of the electroconductive material measured by the dynamic light scattering method.

  Hereinafter, the present invention will be described in detail.

  In the present invention, “conductive material” refers to a conductive material, or a conductive material and its dopant.

  In the present invention, the “conductive material solution” refers to a conductive material or a solution in which a conductive material and its dopant are dissolved or dispersed.

  In the present invention, “composite material” refers to a material obtained by integrally combining two or more different conductive polymers.

In the present invention, the term “impregnation” means that the conductive material is immersed (penetrated) inside the fine irregularities of the dielectric oxide film, or how much the conductive material is immersed in the fine irregularities of the dielectric oxide film. It shows whether it is immersed (penetrated).
The impregnation property can be relatively evaluated by, for example, observing the surface of the dielectric oxide film of the capacitor visually or with a microscope, or observing the cross section of the capacitor with a scanning electron microscope or the like.
<Conductive polymer having acidic group (A)>
The conductive polymer (A) having an acidic group preferably has a unit represented by the following general formula (1) from the viewpoint of exhibiting high conductivity.

  In the present invention, “soluble” means that 0.1 g or more is uniformly dissolved in 10 g of water or an organic solvent (liquid temperature: 25 ° C.).

Further, in the present invention, “conductive” means having a conductivity of 10 ⁻⁸ S / cm or more.

In formula (1), R ^{1 to} R ⁴ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkoxy group having 1 to 24 carbon atoms, or an acidic group. , A hydroxy group, a nitro group, and a halogen atom.

Here, the “acidic group” is a sulfonic acid group or a carboxy group. The sulfonic acid group and the carboxy group may each be included in an acid state (—SO ₃ H, —COOH), or may be included in an ionic state (—SO ₃ —, —COO—).

  The acidic group includes alkali metal salts, ammonium salts, substituted ammonium salts, and the like of acidic groups.

  Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, a dodecyl group, and a tetracosyl group. It is done.

  Examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, an iso-butoxy group, a sec-butoxy group, a tert-butoxy group, a heptoxy group, a hexoxy group, and an octoxy group. , Dodecoxy group, tetracosoxy group and the like.

  Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In formula (1), at least one of R ^{1 to} R ⁴ is an acidic group.

  As the unit represented by the general formula (1), one of R1 to R4 is a linear or branched alkoxy group having 1 to 4 carbon atoms, and any of the other units can be easily manufactured. Those in which one is a sulfonic acid group and the remainder is hydrogen are preferred.

  The conductive polymer (A) having an acidic group preferably contains 10 to 100 mol% of the unit represented by the general formula (1) among all units (100 mol%) constituting the polymer. It is more preferable to contain -100 mol%, and it is especially preferable to contain 100 mol% at the point which is excellent in the solubility to water and an organic solvent irrespective of pH.

  Moreover, it is preferable that the conductive polymer (A) which has an acidic group contains 10 or more units represented by the said General formula (1) in 1 molecule from a viewpoint which is excellent in electroconductivity.

Moreover, 3000-1 million are preferable and, as for the mass average molecular weight of the conductive polymer (A) which has an acidic group, from a viewpoint of electroconductivity, film formability, and film | membrane intensity | strength, 5000-100000 are more preferable.
<Method for Producing Conductive Polymer (A) Having Acidic Group>
The conductive polymer (A) (A) having an acidic group is selected from the group consisting of, for example, an acidic group-substituted aniline represented by the following general formula (1), an alkali metal salt thereof, an ammonium salt, and a substituted ammonium salt. It is obtained by polymerizing at least one compound (monomer) using an oxidizing agent.

In formula (1), R ^{1 to} R ⁴ each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkoxy group having 1 to 24 carbon atoms, or an acidic group. , A hydroxy group, a nitro group, and a halogen atom, and at least one of R ** to R ** is an acidic group.

  Examples of the acidic group-substituted aniline represented by the general formula (1) include sulfonic acid group-substituted anilines having a sulfonic acid group as an acidic group.

  Typical examples of the sulfone group-substituted aniline are aminobenzenesulfonic acids, specifically, o-, m-, p-aminobenzenesulfonic acid, aniline-2,6-disulfonic acid, aniline-2,5- Disulfonic acid, aniline-3,5-disulfonic acid, aniline-2,4-disulfonic acid, aniline-3,4-disulfonic acid and the like are preferably used.

  Examples of sulfone group-substituted anilines other than aminobenzenesulfonic acids include methylaminobenzenesulfonic acid, ethylaminobenzenesulfonic acid, n-propylaminobenzenesulfonic acid, iso-propylaminobenzenesulfonic acid, n-butylaminobenzenesulfonic acid, Alkyl group-substituted aminobenzenesulfonic acids such as sec-butylaminobenzenesulfonic acid and t-butylaminobenzenesulfonic acid; alkoxy group-substituted aminobenzenesulfones such as methoxyaminobenzenesulfonic acid, ethoxyaminobenzenesulfonic acid and propoxyaminobenzenesulfonic acid Acids; Hydroxy group-substituted aminobenzene sulfonic acids; Nitro group-substituted aminobenzene sulfonic acids; Fluoroaminobenzene sulfonic acid, Chloroaminobenzene sulfone , And the like halogen-substituted aminobenzenesulfonic acids such as bromo aminobenzenesulfonic acid.

  Among them, alkyl group-substituted aminobenzene sulfonic acids, alkoxy group-substituted aminobenzene sulfonic acids, hydroxy group-substituted aminobenzene sulfonic acids, or halogen-substituted aminobenzenes are obtained in that polyaniline particularly excellent in conductivity and solubility is obtained. Sulfonic acids are preferred.

  These sulfonic acid group-substituted anilines may be used alone or in a mixture of two or more at any ratio.

  Among these acidic group-substituted anilines represented by the general formula (1), at least selected from the group consisting of alkoxy group-substituted aminobenzene sulfonic acids, alkali metal salts, ammonium salts and substituted ammonium salts in terms of easy production. One compound is particularly preferred.

The oxidizing agent used for the production of the conductive polymer (A) is not limited as long as the standard electrode potential is 0.6 V or more. For example, peroxodisulfuric acid, ammonium peroxodisulfate, sodium peroxodisulfate Peroxodisulfuric acids such as potassium peroxodisulfate; hydrogen peroxide or the like is preferably used.
These oxidizing agents may be used alone or in a combination of two or more at any ratio.
1-5 mol equivalent is preferable with respect to 1 mol of said monomers, and, as for the usage-amount of an oxidizing agent, More preferably, it is 1-3 mol equivalent.

  After polymerization, the solvent is usually filtered off with a filter such as a centrifugal separator. Furthermore, after filtering a filtrate with a washing | cleaning liquid as needed, it is made to dry and the conductive polymer (A) is obtained. In order to remove unreacted monomers, low molecular weight substances, impurities, etc., a method of subjecting the dispersion or solution of the conductive polymer (A) to membrane filtration is preferred. As a solvent used for membrane filtration, for example, a solvent such as water, water containing a basic salt, water containing an acid, water containing an alcohol, or a mixture thereof can be used. As a separation membrane used for membrane filtration, an ultrafiltration membrane is preferable in consideration of removal efficiency of unreacted monomers, low molecular weight substances and impurities.

  In order to remove impurities derived from the basic compound and the oxidizing agent, a method of bringing the dispersion or solution of the conductive polymer (A) into contact with a cation exchange resin is preferable. The form of the cation exchange resin is not particularly limited, and various forms can be used. Examples thereof include spherical fine particles, membranes, and fibers.

The conductive polymer (A) purified in this manner is more excellent because impurities such as low molecular weight substances such as oligomers and monomers, basic compounds, and cations derived from oxidizing agents are sufficiently removed. Conductivity.
<Polymer (B) polymerized with thiophene derivative>
In the present invention, examples of the thiophene derivative include compounds represented by the following general formula (2).

In formula (2), R ^{5 to} R ⁶ are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or bonded to each other to form an alkylene group having 1 to 4 carbon atoms. Also good.

  Examples of the compound represented by the general formula (2) include the following compounds.

When R ^{5 to} R ⁶ are independent, 3,4-dimethoxythiophene, 3-methoxy-4-ethoxythiophene, 3,4-diethoxythiophene, 3-methoxy-4-propoxythiophene, 3-ethoxy- 3 such as 4-propoxythiophene, 3,4-dipropoxythiophene, 3-butoxy-4-methoxythiophene, 3-butoxy-4-ethoxythiophene, 3-butoxy-4-propoxythiophene, 3,4-dibutoxythiophene , 4-dialkoxythiophene.
When R5 to R6 are bonded to each other to form an alkylene group, 3,4-methylenedioxythiophene, 3,4-ethylenedioxythiophene, 3,4-propylenedioxythiophene, 3,4-butyne Examples include 3,4-alkylenedioxythiophenes such as rangeoxythiophene.

  Each of these compounds may be used alone, or two or more kinds thereof may be mixed and used in an arbitrary ratio.

Among these compounds represented by the general formula (2), 3,4-ethylenedioxythiophene is preferable in terms of excellent conductivity and heat resistance.
<Method for producing conductive composite material>
The conductive composite material containing the conductive polymer (A) having an acidic group and the polymer (B) polymerized with a thiophene derivative is a polymer (A) polymerized with a conductive polymer (A) having an acidic group and a thiophene derivative ( It can be obtained by polymerizing a monomer of a thiophene derivative in the presence of a mixture with B) or a conductive polymer (A) having an acidic group. Specifically, the polymerization is performed as follows.

  First, a mixture is prepared by dissolving or dispersing a mixture of a conductive polymer (A) having an acidic group and a monomer of a thiophene derivative in a solvent. As the conductive polymer (A) having an acidic group, a solid polymer may be used, or a polymer dispersed or dissolved in a solvent after purification may be used, for example.

Separately, an oxidizing agent solution or a mixture of an oxidizing agent and a catalyst is dissolved in a solvent to prepare an oxidizing agent solution.
Polymerization is performed by mixing the mixed solution and the oxidizing agent solution. At this time, the oxidant solution may be dropped into the mixed solution, the mixed solution may be dropped into the oxidant solution, or the mixed solution and the oxidant solution may be dropped simultaneously into the reaction vessel or the like. Good.
Examples of the conductive polymer monomer include thiophene derivatives, pyrrole derivatives, and aniline derivatives.

  The molar ratio of the conductive polymer (A) to the thiophene derivative is preferably: conductive polymer (A) / thiophene derivative = 1 / 0.01 to 1/10, 1 / 0.05 to 1 / 5 is more preferable. If the ratio of the thiophene derivative is high, the particle size of the polymer of the thiophene derivative may become large and may not penetrate into the dielectric oxide film of the capacitor. May decrease.

  As the oxidizing agent, the oxidizing agent exemplified above in the description of the production of the conductive polymer (A) can be used. The same kind may be sufficient as the oxidizing agent used for manufacture of a conductive polymer (A), and the oxidizing agent used for manufacture of a conductive composite, and a different kind may be sufficient as it.

  The amount of the oxidizing agent used is preferably 0.5 to 5.0 mol equivalent, more preferably 1.0 to 3.0 mol equivalent, relative to 1 mol of the thiophene derivative.

  Examples of the catalyst include transition metal compounds such as iron and copper. Specific examples include ferric sulfate, ferric nitrate, and cupric chloride.

  Further, metal halogen compounds such as boron trifluoride, metal oxides such as silver oxide and cesium oxide, iron (III) salts of organic acids, and the like can also be used as catalysts. Specifically, examples of iron (III) salts of organic acids include alkyl sulfonic acids such as methane or lauryl sulfuric acid, aliphatic carboxylic acids such as 2-ethylhexyl carboxylic acid, and aliphatic perfluorocarboxylic acids such as trifluoroacetic acid. And Fe (III) salts such as dicarboxylic acids such as oxalic acid, alkylbenzenesulfonic acid, p-toluenesulfonic acid, and dodecylbenzenesulfonic acid.

  The amount of the catalyst used is preferably 0.01 to 1 mol equivalent, more preferably 0.05 to 0.5 mol equivalent, relative to 1 mol of the thiophene derivative.

  Solvents used in the mixed solution and oxidant solution include polar solvents such as water, pure water, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide; cresol, phenol, etc. Phenols; alcohols such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; hydrocarbons such as hexane, benzene and toluene; carboxylic acids such as formic acid and acetic acid; carbonate compounds such as ethylene carbonate and propylene carbonate Ether compounds such as dioxane and diethyl ether; chains such as ethylene glycol dialkyl ether, propylene glycol dialkyl ether, polyethylene glycol dialkyl ether, and polypropylene glycol dialkyl ether Heterocyclic compounds such as 3-methyl-2-oxazolidinone; ethers acetonitrile, glutarodinitrile, methoxy acetonitrile, propionitrile, nitrile compounds such as benzonitrile and the like. These solvents may be used alone, as a mixture of two or more kinds, or as a mixture with other organic solvents.

  The temperature during the polymerization is preferably 50 ° C. or lower, more preferably 25 ° C. or lower, and particularly preferably 10 ° C. or lower. If the temperature at the time of superposition | polymerization is 25 degrees C or less, electroconductivity will improve more. However, when the temperature at the time of polymerization is too low, the polymerization reaction hardly proceeds, and the polymerization time may be set longer. Moreover, it exists also in the tendency for the surface smoothness of a coating film to fall. From such a viewpoint, the temperature during polymerization is preferably −20 ° C. or higher, more preferably −10 ° C. or higher.

  The polymerization time is preferably 1 to 72 hours, more preferably 2 to 48 hours in consideration of reactivity and productivity.

  The polymerization is preferably performed in the presence of an acid. Conducting the polymerization in the presence of an acid improves the conductivity.

  Acids used in the polymerization include sulfuric acid, nitric acid, phosphoric acid, boric acid, chromic acid, halogen oxoacids such as hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hydrochloric acid, hydrobromic acid, iodine. Hydrofluoric acid, hexafluoroantimonic acid, tetrafluoroboric acid, hexafluorophosphoric acid, trifluoromethanesulfonic acid, nonafluoro-1-butanesulfonic acid, 1,1,1-trifluoro-N-[(trifluoromethyl) sulfonyl Methanesulfonamide, dibenzenesulfonimide, 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide, bis [nonafluorobutanesulfone] imide and the like. These may be used alone or in combination of two or more.

  The amount of the acid used is preferably 0.05 to 50 mol equivalent, more preferably 0.1 to 20 mol equivalent, relative to 1 mol of the thiophene derivative. If the amount of the acid used is 0.05 mol equivalent or more, the effect of improving the conductivity is sufficiently obtained. However, even if the amount exceeds 50 mol equivalent, the conductivity reaches its peak, which only increases the cost.

  After polymerization, the solvent is usually filtered off with a filter such as a centrifugal separator. Further, the filtered material is washed with a washing liquid as necessary, and dried to obtain a conductive material in which the conductive polymer (A) and the polymer of the thiophene derivative are combined.

  Note that the conductive material thus obtained may contain unreacted thiophene derivatives, impurities, and the like, which may be a factor that hinders conductivity. Therefore, it is preferable to purify the conductive composite to remove impurities.

  In order to remove unreacted thiophene derivatives and impurities, a method of membrane filtration of the reaction solution after polymerization is preferred. At this time, a polymerization solvent may be added to the reaction solution after polymerization to dilute to a desired concentration, and then membrane filtration may be performed. As a separation membrane used for membrane filtration, an ultrafiltration membrane is preferable in consideration of removal efficiency of unreacted thiophene derivatives and impurities.

Note that the conductive composite after purification is in a state of being dispersed or dissolved in a solvent such as water. Accordingly, if all the solvent is removed with an evaporator or the like, a solid conductive composite can be obtained, but the conductive composite may be used in a state dispersed or dissolved in the solvent.
<Condition (I)>
The volume average particle diameter of the conductive composite material of the present invention is 25 nm or less. If the volume average particle diameter is 25 nm or less, the conductive material is sufficiently impregnated into the fine irregularities of the dielectric oxide film 12, so that a solid electrolytic capacitor having a high capacity expression rate can be obtained. The volume average particle diameter of the conductive material is preferably 20 nm or less, more preferably 10 nm or less, and particularly preferably 5 nm or less in that the impregnation property is superior.

  The volume average particle diameter of the conductive composite material is a value measured as follows.

  First, a conductive composite material solution having a concentration of 1% by weight of a conductive composite material is prepared, and the particle distribution is measured by a dynamic light scattering method using a dynamic light scattering particle size measuring device, and the viscosity of pure water is measured. Correct with. Then, among the obtained one or more peaks, the volume average particle diameter of the minimum particle distribution including the peak having the minimum particle diameter is obtained, and this is set as the volume average particle diameter of the conductive material.

In the present invention, the “minimum particle distribution” means a particle distribution measured by a dynamic light scattering method, corrected by the viscosity of pure water, and then analyzed by analyzing it. The distribution with the smallest particle size. Specifically, as shown in FIG. 3, among one or more peaks P1, P2, P3,... Obtained by measuring the particle distribution, a particle distribution including a peak P1 having a minimum particle diameter (see FIG. 3). 3 is a region of S). When there is one peak obtained by measuring the particle distribution by the dynamic light scattering method, this particle distribution is the minimum particle distribution. Further, when a plurality of particle distributions overlap, the waveforms may be separated by a general analysis method using a Gauss function, a Lorentz function, or the like incorporated in general-purpose software.
<Compound (C) having OH group>
As the compound (C) having an OH group, those that are soluble are preferred.

  In addition, the number of hydroxy groups in one molecule of the compound (C) is preferably 2 or more, and more preferably 3 or more. If the number of hydroxy groups is 2 or more, the acidic group of the conductive polymer (A) and the hydroxy group of the compound (C) are bonded to each other during heating, and the elimination of the acidic group is suppressed and the conductivity is good. We think that we can expect effect to maintain.

  Examples of such a compound (C) include D-mannitol, pentaerythritol, glycerin, and hydroquinone. In addition to these, compounds having three hydroxy groups include 1,2,4-butanetriol, 2- (hydroxymethyl) -1,3-propanediol, trimethylolethane, 2-deoxy-D-ribose. , Tris (hydroxymethyl) aminomethane, triethanolamine, etc .; compounds having 4 hydroxy groups such as erythritol, threitol, arabinose, fucose, lyxose, rhamnose, ribose, xylose, etc .; xylitol as compounds having 5 hydroxy groups , Ribitol, arabinitol, allose, fructose, galactose, glucose, gulose, mannose, psicose, sorbose, tagatose, talose, etc .; compounds having 6 hydroxy groups such as galactitol, allitol, iditol It inositol, talitol, also be used as a compound dipentaerythritol (C). These may be used alone or in combination of two or more. Among these, a compound having 3 or more hydroxy groups such as D-mannitol, pentaerythritol, and glycerin is preferable in terms of improving heat resistance. In particular, D-mannitol is preferable in terms of improving heat resistance.

The content of the compound (C) is preferably from 0.1 to 50 mol equivalent, more preferably from 0.3 to 20 mol equivalent, based on 1 mol of the conductive complex from the viewpoint of maintaining conductivity.
<Other ingredients>
The conductive composition of the present invention may contain a solvent. Examples of the solvent include water, ultrapure water, a mixed solvent of these and a water-soluble organic solvent, and the like.

The water-soluble organic solvent is not particularly limited as long as it is mixed with water. Specific examples of water-soluble organic solvents include water or alcohols such as methanol, ethanol, isopropanol, n-propanol, and n-butanol; ketones such as acetone, methyl ethyl ketone, ethyl isobutyl ketone, and methyl isobutyl ketone; ethylene glycol, Ethylene glycols such as ethylene glycol methyl ether and ethylene glycol mono-n-propyl ether; propylene glycols such as propylene glycol, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether and propylene glycol propyl ether; dimethylformamide and dimethyl Amides such as acetamide; Pyrrolidones such as N-methylpyrrolidone and N-ethylpyrrolidone; N-methyl Pyrrolidone, pyrrolidones such as N- ethyl-pyrrolidone; methyl lactate, ethyl lactate, beta-methoxyisobutyrate methyl butyrate, hydroxypropyl esters such as α- hydroxy methyl isobutyrate and the like.
<Solid electrolytic capacitor>
An embodiment of a solid electrolytic capacitor using the conductive material of the present invention will be described.
FIG. * Schematically shows the configuration of the capacitor of this embodiment. The solid electrolytic capacitor 10 of this example includes a film-forming metal 11, a dielectric oxide film 12 formed on the film-forming metal 11, a solid electrolyte layer 13 formed on the dielectric oxide film 12, and a solid electrolyte layer. 13 is a multilayer solid electrolytic capacitor including a graphite layer 14 formed on 13 and a metal layer 15 formed on the graphite layer 14.
(Coating metal)
The film-forming metal 11 is a porous metal body having a valve action and has conductivity. As such a film-forming metal 11, a normal electrode (valve action metal body) used for a solid electrolytic capacitor can be used, and specifically, an electrode made of a metal material such as aluminum, tantalum, niobium, or nickel can be cited. . Examples of the form include a metal foil and a metal sintered body.
(Dielectric oxide film)
The dielectric oxide film 12 is formed by anodizing the film forming metal 11.
As shown in FIG. 1, the dielectric oxide film 12 formed by anodizing the film-forming metal 11 reflects the surface state of the film-forming metal 11 and has a fine uneven surface. The period of the unevenness depends on the type of the film-forming metal 11 and the like, but is usually about 200 nm or less. Further, the depth of the recesses (micropores) for forming the recesses and projections is not particularly determined because it is particularly dependent on the type of the film-forming metal 11, but for example, when aluminum is used, the depth of the recesses is several tens. It is about nm to 1 μm.
(Solid electrolyte layer)
The solid electrolyte layer 13 includes a conductive material that satisfies the following condition (I), the conductive material is composed of two or more types of conductive polymers, and at least one of the conductive polymers is a soluble conductive polymer. (A).
Condition (I): Among one or more peaks obtained by measuring the particle distribution by a dynamic light scattering method using a conductive material solution containing 1% by mass of a conductive material, the peak having the smallest particle diameter The volume average particle diameter of the minimum particle distribution to be included is 25 nm or less.

  As described above, the solid electrolyte layer 13 is formed by applying a conductive material solution containing a conductive material satisfying the above condition (I) on the dielectric oxide film 12 and drying it. Since the solid electrolyte layer 13 formed in this way is sufficiently impregnated with the conductive material even inside the fine irregularities of the dielectric oxide film 12, the capacity expression rate of the obtained solid electrolytic capacitor 10 is improved. To do.

  The content of the conductive material in 100% by mass of the conductive material solution is preferably 9% by mass or less, and more preferably 5% by mass or less. If the content of the conductive material is 9% by mass or less, the wettability with respect to the film-forming metal 11 on which the dielectric oxide film 12 is formed and the separator provided in the winding type solid electrolytic capacitor described later is improved. The conductive material can be sufficiently impregnated into the fine irregularities without being deposited on the surface of the dielectric oxide film 12.

  The lower limit value of the content of the conductive material is not particularly limited, but is preferably 0.1% by mass or more in that the solid electrolyte layer 13 having a desired thickness can be easily formed.

The conductive material solution used for forming the solid electrolyte layer 13 includes, in addition to the conductive material, a conductive polymer other than the conductive material (another conductive polymer), an additive such as a surfactant, It may contain other materials.
Examples of other conductive polymers include poly (3,4-ethylenedioxythiophene), polypyrrole, and polyaniline. In addition, when these other conductive polymers are used, it is preferable to use a dopant (for example, polystyrene sulfonic acid) in combination.

  Examples of the surfactant include an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, and a fluorine surfactant. These surfactants may be used alone or in combination of two or more.

When the conductive material solution contains a surfactant, the content of the surfactant in 100% by mass of the conductive material solution is preferably 0.1 to 20% by mass, and more preferably 0.1 to 5% by mass. . If the content of the surfactant is 0.1% by mass or more, the surface tension of the conductive material solution can be reduced. Therefore, the impregnation property into the fine irregularities of the dielectric oxide film 12 is improved, and the conductivity of the solid electrolyte layer 13 is increased. On the other hand, if the content of the surfactant is 20% by mass or less, the conductivity can be maintained well.
(Graphite layer)
The graphite layer 14 is formed by applying a graphite liquid on the solid electrolyte layer 13 or immersing the film-forming metal 11 in which the dielectric oxide film 12 and the solid electrolyte layer 13 are sequentially formed in the graphite liquid.
(Metal layer)
Examples of the metal layer 15 include a silver layer such as adhesive silver, an aluminum electrode, a tantalum electrode, a niobium electrode, a titanium electrode, a zirconium electrode, and a magnesium electrode.
In the solid electrolytic capacitor 10 of the present invention described above, it is composed of two or more kinds of conductive polymers, and at least one of the conductive polymers is a soluble conductive polymer (A), and the above condition (I) Since the solid electrolyte layer 13 is formed using a conductive material satisfying the above, the conductive material is sufficiently impregnated into the fine irregularities of the dielectric oxide film 12. Therefore, since the solid electrolyte layer 13 is formed even inside the fine irregularities of the dielectric oxide film 12, the capacity development rate is high.

<Method for manufacturing solid electrolytic capacitor>
Next, an example of a method for manufacturing the solid electrolytic capacitor 10 will be described.

  The method for producing a solid electrolytic capacitor of the present invention comprises two or more kinds of conductive polymers on a dielectric oxide film 12 formed on the surface of a film-forming metal 11, and at least one of the conductive polymers is A step of applying a conductive material solution that is a soluble conductive polymer (A) and satisfies the above condition (I) (application step), and the applied conductive material solution is dried to form the solid electrolyte layer 13. Process (drying process).

  In the present invention, processes other than the process of forming the solid electrolyte layer 13 are performed by a known technique. For example, when the solid electrolytic capacitor 10 shown in FIG. 1 is manufactured, the dielectric layer 12 is formed by anodic oxidation after the surface layer vicinity of the film forming metal 11 such as an aluminum foil is made porous by etching. Next, after the solid electrolyte layer 13 is formed on the dielectric oxide film 12, this is immersed in the graphite liquid or the graphite liquid is applied to form the graphite layer 14 on the solid electrolyte layer 13, and the graphite layer A metal layer 15 is formed on 14. Furthermore, an external terminal (not shown) is connected to a cathode and an anode (both not shown) to provide a solid electrolytic capacitor 10.

  Here, the process of forming the solid electrolyte layer 13 will be described in detail.

  The solid oxide layer 13 and the dielectric oxide film 12 formed on the surface of the film-forming metal 11 are made of two or more kinds of conductive polymers, and at least one of the conductive polymers is a soluble conductive polymer. (A), a conductive material solution satisfying the above condition (I) is applied (application process), the fine unevenness of the dielectric oxide film 12 is impregnated with the conductive material, and then dried (drying). Process).

  In the present invention, “application” refers to forming a coating film (layer), and coating and immersion are also included in the application.

The conductive material solution can be obtained by dissolving a conductive material and, if necessary, other conductive polymers, dopants, surfactants and other additives in a solvent.
In one embodiment of the present invention, the conductive material solution is adjusted so that the content of the conductive material is 9% by mass or less, more preferably 5% by mass or less in 100% by mass of the conductive material solution.

If the content of the conductive material is 9% by mass or less, the wettability with respect to the film-forming metal 11 on which the dielectric oxide film 12 is formed and the separator provided in the winding type solid electrolytic capacitor described later is improved. The conductive material can be sufficiently impregnated into the fine irregularities without being deposited on the surface of the dielectric oxide film 12.
The lower limit value of the content of the conductive material is not particularly limited, but is preferably 0.1% by mass or more in that the solid electrolyte layer 13 having a desired thickness can be easily formed.

In another embodiment of the present invention, the conductive material solution is adjusted so that the surface tension is less than 67 mN / m, more preferably 60 mN / m or less.
As described later in detail, a solvent used for the conductive material solution is water, an organic solvent, or a mixed solvent of water and an organic solvent. For example, when a mixed solvent is used as the solvent, the surface tension of the conductive material solution tends to decrease as the proportion of the organic solvent increases.

  Examples of the solvent used for the conductive material solution include water, an organic solvent, and a mixed solvent of water and an organic solvent as described above.

  Examples of the organic solvent include alcohols such as methanol, ethanol, isopropyl alcohol, propyl alcohol, and butanol; ketones such as acetone, methyl ethyl ketone, ethyl isobutyl ketone, and methyl isobutyl ketone; ethylene glycol, ethylene glycol methyl ether, and ethylene glycol mono-n. Ethylene glycols such as propyl ether; propylene glycols such as propylene glycol, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether and propylene glycol propyl ether; amides such as dimethylformamide and dimethylacetamide; N-methylpyrrolidone Pyrrolidones such as N-ethylpyrrolidone; methyl lactate, ethyl lactate, β- Tokishiiso methyl butyrate, hydroxypropyl esters and γ- butyrolactone, such as α- hydroxy methyl isobutyrate and the like. These organic solvents may be used individually by 1 type, and may use 2 or more types together. Among these, alcohols are preferable from the viewpoint of solubility in water and handling, and methanol and isopropyl alcohol are particularly preferable.

  When using a mixed solvent as a solvent, 4-70 mass% is preferable and, as for content of the organic solvent in 100 mass% of mixed solvents, 10-50 mass% is more preferable. When the content of the organic solvent is within the above range, the conductive material dissolves well.

  As a method for applying the conductive material solution, dip coating method, brush coating method, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, spray coating method , Flow coating method, screen printing method, flexographic printing method, offset printing method, ink jet printing method and the like. In particular, the dip coating method (immersion method) is preferable in terms of easy operation.

  When the conductive material solution is applied by the dip coating method, the immersion time in the conductive material solution is preferably 1 to 30 minutes from the viewpoint of workability. In addition, when dip-coating, it is also effective to dip at the time of depressurization to return to normal pressure, or to pressurize at the time of dip.

  As a drying method after applying the conductive material solution, heat drying is preferable. For example, air drying or a method of physically drying by spinning may be used.

  Moreover, although drying conditions are determined by the kind of electroconductive material and a solvent, 20-190 degreeC is preferable normally from a viewpoint of drying property, and drying time has preferable 1 to 30 minutes.

In the manufacturing method of the solid electrolytic capacitor of the present invention described above, the dielectric oxide film formed on the film-forming metal is composed of two or more kinds of conductive polymers, and at least one of the conductive polymers is Since the solid electrolyte layer is formed by applying a conductive material solution satisfying the following condition (I), which is a soluble conductive polymer (A), the conductive material is placed in the fine irregularities of the dielectric oxide film. Until fully impregnated. Therefore, a solid electrolyte layer having high conductivity can be formed on the dielectric oxide film, and a solid electrolytic capacitor having a high capacity expression rate can be easily manufactured.
In recent years, the porous film-forming metal is further miniaturized or has various forms of micropores, so the dielectric oxide film is also finer and more complicated inside, According to the present invention, a conductive material can be sufficiently impregnated into the finer and more complicated dielectric oxide film.
Therefore, the solid electrolytic capacitor obtained by the present invention has a high capacity development rate because the solid electrolyte layer sufficiently impregnated with the conductive material is formed on the dielectric oxide film even inside the fine irregularities. Excellent performance as a capacitor.

Further, according to the present invention, since the solid electrolyte layer can be formed on the dielectric oxide film without performing chemical oxidative polymerization or electrolytic polymerization, there are few impurities in the solid electrolyte layer, and the manufacturing process is hardly complicated.
In the above description, aluminum has been described as an example of the film-forming metal, but other metal such as tantalum, niobium, and nickel-plated products are not particularly limited to aluminum.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

The measurement / evaluation methods in Examples and Comparative Examples, and the production methods of the conductive polymer (A) and the conductive material are as follows.
<Measurement and evaluation method>
(Evaluation of volume average particle diameter)
Prepare a conductive material solution with a conductive material concentration of 1% by mass, and use a dynamic light scattering type particle size measuring device (manufactured by Nikkiso Co., Ltd., “Nanotrack”) to determine the particle distribution by the dynamic light scattering method. It was measured and corrected with the viscosity of pure water. Of the obtained one or more peaks, the volume average particle size of the minimum particle distribution including the peak having the smallest particle size was determined, and this was defined as the volume average particle size of the conductive material.
(Evaluation of conductivity)
By applying the conductive composition on a glass substrate with a manual spinner ASC-4000 (manufactured by Actes Inc.), and leaving the conductive composition to stand on a hot plate set at 120 ° C. for 10 minutes, A conductor (test piece 1) in which a coating film having a film thickness of about 0.1 μm was formed on a glass substrate was produced.

The surface resistance value of the obtained test piece 1 was measured at room temperature (25 ° C.) by attaching a series four probe probe to a resistivity meter Loresta GP (manufactured by Mitsubishi Chemical Corporation). The film thickness of the coating film was measured using a nanoscale hybrid microscope VN-8000 (manufactured by Keyence Corporation), multiplied by the surface resistance value to obtain the volume resistivity, the reciprocal of this volume resistivity was calculated, and the conductivity The rate was determined. It means that it is excellent in electroconductivity, so that the value of electrical conductivity is high.
(Evaluation of heat resistance)
By applying the conductive composition on a glass substrate with a manual spinner ASC-4000 (manufactured by Actes Inc.), and leaving the conductive composition to stand on a hot plate set at 160 ° C. for 60 minutes, A conductor (test piece 2) in which a coating film having a thickness of about 0.1 μm was formed on a glass substrate was produced.

About the obtained test piece 2, the surface resistance value was measured similarly to the previous test piece 1, and electric conductivity was calculated | required. It means that it is excellent in heat resistance, so that the value of electrical conductivity is high.
<Manufacture of conductive materials>
<Manufacture of conductive polymer (A)>
100 mmol of 2-aminoanisole-4-sulfonic acid was stirred and dissolved in water containing 100 mmol of triethylamine at 25 ° C., and an aqueous solution of 100 mmol of ammonium peroxodisulfate was added dropwise. After completion of the dropwise addition, the reaction product was filtered and washed after further stirring at 25 ° C. for 12 hours. Thereafter, it was dried to obtain 15 g of powdery poly (2-sulfo-5-methoxy-1,4-iminophenylene) (A). The volume average particle diameter of the obtained (A) was 0.95 nm. Moreover, the mass mean molecular weight calculated | required by the gel permeation chromatography (GPC) in polystyrene sulfonate sodium conversion was about 25000.

  5 parts by mass of the obtained conductive polymer (A) is dissolved in 95 parts by mass of water at 25 ° C., and the column is filled with an acidic cation exchange resin so as to be 50 parts by mass with respect to 100 parts by mass of the aqueous polymer solution. Then, the aqueous polymer solution was passed through the column at a flow rate of SV = 8 to perform cation exchange treatment, and the aqueous polymer solution was purified.

The ratio of the conductive polymer (A) in 100% by mass of the purified polymer aqueous solution (A-1) was 4.4% by mass.
<Example 1>
12.9 g of the purified polyaniline aqueous solution (A-1) and 0.2 g of 3,4-ethylenedioxythiophene (EDOT) are mixed as a thiophene derivative, and 0.55 g of 10% by mass sulfuric acid aqueous solution and 35 g of pure water was added and stirred with a stirrer to obtain a mixed solution. The molar ratio of polyaniline (A-1) and thiophene derivative (conductive polymer (A) / thiophene derivative) in the mixed solution is 2/1.

  Separately, 0.42 g of ammonium peroxodisulfate and 0.15 g of ferric sulfate were dissolved in 20 g of ultrapure water to obtain an oxidant solution.

Subsequently, while stirring the mixed solution at 10 ° C., an oxidizing agent solution was dropped into the mixed solution, stirred at 10 ° C. for 3 hours, and stirred at 40 ° C. for 24 hours to perform a polymerization reaction. This conductive material solution was purified using an ultrafiltration membrane having a fractional molecular weight of 50 kDa. The pure water used for purification was 2000 g.
The particle diameter, conductivity, and immersion property of the purified conductive composite material (D-1) were evaluated. The results are shown in Table 1.
<Example 2>
Polymerization and purification were conducted in the same manner as in Example 1 except that 6.45 g of the purified polyaniline aqueous solution (A-1) and 0.2 g of 3,4-ethylenedioxythiophene (EDOT) were mixed as a thiophene derivative ( D-2).
The particle diameter, conductivity and dipping property of the conductive composite material (D-2) were evaluated. The results are shown in Table 1.
<Example 3>
Polymerization and purification were performed in the same manner as in Example 1 except that 3.23 g of the purified polyaniline aqueous solution (A-1) and 0.2 g of 3,4-ethylenedioxythiophene (EDOT) were mixed as a thiophene derivative ( D-3).
The particle diameter, conductivity and dipping property of the conductive composite material (D-3) were evaluated. The results are shown in Table 1.
<Example 4>
Polymerization and purification were carried out in the same manner as in Example 1 except that 129 g of the purified polyaniline aqueous solution (A-1) and 0.2 g of 3,4-ethylenedioxythiophene (EDOT) were mixed as a thiophene derivative (D- 4).
The particle diameter, conductivity, and immersion property of the conductive composite material (D-4) were evaluated. The results are shown in Table 1.
<Comparative Example 1>
Using the purified polyaniline aqueous solution (A-1), the electrical conductivity, the immersion property, and the particle diameter of A-1 were evaluated. The results are shown in Table 1.
<Comparative example 2>
In place of the purified polyaniline aqueous solution (A-1), polymerization and purification were conducted in the same manner as in Example 2 except that polystyrene sulfonic acid obtained by treating sodium polystyrene sulfonate having a weight average molecular weight of 50,000 with an acidic cation exchange resin was used. did.

  The molar ratio of polystyrene sulfonic acid and thiophene derivative in the mixed solution is 1/1.

Table 1 shows the particle diameter, conductivity, and immersion results.
<Comparative Example 3>
Commercially available PEDOT / PSS (poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid) material solution (manufactured by Clevios, “PH510”, PEDOT / PSS volume average particle diameter 26.7 nm, concentration 1.2 mass) %) Was used to evaluate the conductivity, immersion, and A-1 particle size. The results are shown in Table 1.
(Evaluation of immersion)
A rolled aluminum capacitor is cut out in a flag shape, and anodized in an aqueous solution of ammonium adipate with a concentration of 3% by mass for 120 minutes under conditions of a voltage of 5.7 V and a temperature of 70 ° C., and a dielectric oxide film is formed on the surface of the aluminum foil. An aluminum element was obtained. On the dielectric oxide film of this aluminum element, 5 μl of a conductive material solution was dropped and allowed to stand at room temperature for 5 minutes. Thereafter, the remaining rate of the surface layer surface of the conductive material solution on the dielectric oxide film was evaluated from the area of the dropped portion before and after standing for 5 minutes.

The amount present in the substrate surface layer relative to the dripped surface is
0% or more and less than 10%
10% or more and less than 20%
20% or more and less than 50% △,
50% or more x
It was.

As is clear from the results in Table 1, in each example, the conductive material had a small particle diameter, good heat resistance, and was generally impregnated into the fine irregularities of the dielectric oxide film.
On the other hand, in the case of Comparative Example 1 using a purified polyaniline (A) single solution, the particle diameter was small and the immersion property in dielectric and other oxide films was good, but the heat resistance was very poor. Moreover, when the commercially available PEDOT / PSS (cleviosPH510) of the comparative example 3 was used, although heat resistance was good, the particle diameter was large and the immersion property was bad.
<Example 5>
0.25 g of D-mannitol as a compound (C) is added to 5.0 g of the conductive material ((D-1) solid content 1.0%) obtained in Example 1, and the mixture is stirred with a stirrer. A functional composite material (D-5) was obtained.
The particle diameter, conductivity and dipping property of the conductive composite material (D-5) were evaluated. The results are shown in Table 2.
<Example 6>
To 5.0 g of the conductive material ((D-2) solid content 1.0%) obtained in Example 2, 0.25 g of glycerin was added as the compound (C) and stirred with a stirrer. A material (D-6) was obtained.

  The particle diameter, conductivity and dipping property of the conductive composite material (D-6) were evaluated. The results are shown in Table 2.

  As is apparent from Table 2, the conductive composite materials of Examples 5 and 6 containing the compound (C) having a hydroxy group and excellent heat resistance and high conductivity as compared with the case of not containing the compound (C). Indicated.

DESCRIPTION OF SYMBOLS 10 Solid electrolytic capacitor 11 Film-forming metal 12 Dielectric oxide film 13 Solid electrolyte layer 14 Graphite layer 15 Metal layer 20 Solid electrolytic capacitor 21 Anode 22 Cathode 23 Separator 24 External terminal

Claims (5)

A conductive polymer (A) having an acidic group;
A conductive composite material comprising a polymer (B) obtained by polymerizing a thiophene derivative and satisfying the following condition (I).
Condition (I): Among one or more peaks obtained by measuring the particle distribution by a dynamic light scattering method using a conductive composite liquid containing 1% by mass of a conductive composite material, the particle diameter is minimized. The volume average particle size of the minimum particle distribution including the peak is 25 nm or less. The conductive composite material according to claim 1, wherein the conductive polymer (A) having an acidic group has a repeating unit represented by the following general formula (1).

In formula (1), R ^{1 to} R ⁴ each independently represent —H, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkoxy group having 1 to 24 carbon atoms, or an acidic group. Or its salt, a hydroxyl group, a nitro group, -F, -Cl, -Br or -I, and at least one of R ^{1 to} R ⁴ is an acidic group or a salt thereof. Here, the acidic group is a sulfonic acid or a carboxy group. )   The conductive composite material according to claim 1 or 2, wherein the conductive composite material further contains a compound (C) having an OH group. It is a manufacturing method of the conductive composite material according to any one of claims 1 to 3,
A method for producing a conductive composite material by polymerizing a thiophene derivative in the presence of a conductive polymer (A) having an acidic group and satisfying the following condition (I).
Condition (I): Among the one or more peaks obtained by measuring the particle distribution by a dynamic light scattering method using a conductive composite material liquid containing 1% by mass of a conductive material, the peak having the smallest particle diameter The volume average particle size of the minimum particle distribution including is 25 nm or less.    The manufacturing method of a solid electrolytic capacitor which has the process of forming a solid electrolyte layer using the electroconductive composite material as described in any one of Claims 1-3.