Method for manufacturing a conductive composite, and method for manufacturing a capacitor

Abstract

To provide: a method for producing a conductive composite that is suitable for producing a conductive polymer dispersion that has a reduced viscosity increase during storage and gives a coating film having good conductivity after cure; and a method for producing a capacitor.SOLUTION: A method for producing a conductive composite comprises: a step A of adding a water-soluble azo polymerization initiator to a first reaction mixture comprising a polymerizable anionic monomer and water to obtain a second reaction mixture comprising a polyanion obtained by polymerization of the polymerizable anionic monomer; and a step B of adding a polymerizable monomer, which forms a π-conjugated conductive polymer, and an arbitrary radical polymerization initiator to the second reaction mixture to obtain a third reaction mixture comprising a conductive composite in which the π-conjugated conductive polymer and the polyanion are complexed. When the second reaction mixture supplied to the step B is analyzed by GPC, a ratio, Sm / Sp, of a peak area Sp of the polyanion and a peak area Sm of the polymerizable anionic monomer is 3.0% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing a conductive composite and a method for producing a capacitor.

Background Art

[0002] A π-conjugated conductive polymer whose main chain is composed of a π-conjugated system forms a conductive composite by doping with a polyanion having an anion group, and exhibits dispersibility in water. A method for manufacturing a capacitor is disclosed in which a paint using a conductive polymer dispersion liquid containing a conductive composite (sometimes referred to as a conductive polymer-containing liquid) as a material is applied to a dielectric layer provided on the surface of an anode made of valve metal, dried to form a solid electrolyte layer, and a cathode is disposed opposite thereto (for example, Patent Document 1). According to this disclosure, the performance of the capacitor is improved by including a specific unsaturated aliphatic alcohol compound in the paint.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the above-mentioned conductive polymer dispersion liquid used for manufacturing a capacitor and the paint containing the same are required to have an appropriately low viscosity in order to penetrate into the porous structure of the dielectric layer. In addition, the solid electrolyte layer formed by drying the coating film is required to have high conductivity. The viscosity of a conventional conductive polymer dispersion liquid containing a conductive composite increases significantly compared to the initial value after being stored for several weeks, and is not always easy to use.

[0005] The present invention provides a method for manufacturing a conductive composite and a method for manufacturing a capacitor, which are suitable for producing a conductive polymer dispersion liquid that reduces viscosity increase during storage and has good conductivity of the coating film after curing. [Means for solving the problem]

[0006] [1] A method for producing a conductive composite, comprising: step A, to obtain a second reaction solution containing a polyanion formed by polymerization of the polymerizable anion monomer by adding a water-soluble azo polymerization initiator to a first reaction solution containing a polymerizable anion monomer and water; and step B, to obtain a third reaction solution containing a conductive composite in which the polyanion is complexed by adding a polymerizable monomer that forms a π-conjugated conductive polymer and an arbitrary radical polymerization initiator to the second reaction solution by forming the π-conjugated conductive polymer, wherein when the second reaction solution subjected to step B is analyzed by a gel permeation chromatography system, the ratio expressed as Sm / Sp of the peak area of ​​the detection signal intensity corresponding to the polyanion content to the peak area of ​​the detection signal intensity corresponding to the polymerizable anion monomer content is 3.0% or less. [2] The method for producing a conductive composite according to [1], wherein in step A, the entire amount of the water-soluble azo polymerization initiator to be added until the second reaction solution in which the polymerization reaction has been completed is prepared in advance as an aqueous solution and added gradually dropwise over a period of 0.5 hours or more. [3] A method for producing a conductive composite according to [1], wherein in step A, the entire amount of the water-soluble azo polymerization initiator to be added until the second reaction solution in which the polymerization reaction has been completed is obtained is added all at once, and thereafter the second reaction solution in which the polymerization reaction has been completed is obtained, and subsequently the unpolymerized polymerizable anion monomer contained in the second reaction solution is removed by contacting it with an anion exchange resin, and the purified second reaction solution is subjected to the subsequent step B. [4] A method for producing a conductive composite according to any one of [1] to [3], wherein the water-soluble azo polymerization initiator used in step A is 2,2'-azobis[2-(2-imidazolin-2-yl)propane]. [5] The method for producing a conductive composite according to [1], wherein the water-soluble azo polymerization initiator used in step A is 4,4'-azobis(4-cyanovaleric acid) or a salt thereof, and the entire amount of the water-soluble azo polymerization initiator to be added until the second reaction solution in which the polymerization reaction has been completed is added all at once, and then the second reaction solution in which the polymerization reaction has been completed is obtained and the second reaction solution is subjected to the subsequent step B without being purified by contacting it with an anion exchange resin. [6] A method for producing a conductive composite according to any one of [1] to [5], wherein the water-soluble azo polymerization initiator added to the first reaction solution in step A forms a salt. [7] A method for producing a conductive composite according to any one of [1] to [6], wherein the weight-average molecular weight of the polyanion contained in the second reaction solution obtained in step A is 100,000 to 400,000. [8] A method for producing a conductive composite according to any one of [1] to [7], wherein the polymerizable monomer forming the π-conjugated conductive polymer is (3,4-ethylenedioxythiophene). [9] The method for producing a conductive composite according to any one of [1] to [8], wherein the polymerizable anion monomer that forms the polyanion is styrene sulfonic acid or a salt thereof. A method for manufacturing a capacitor, comprising the steps of: obtaining a conductive composite by a method for manufacturing a conductive composite described in any one of [1] to [9]; preparing a conductive polymer dispersion containing the conductive composite; and applying the conductive polymer dispersion to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal, and drying it to form a solid electrolyte layer. [Effects of the Invention]

[0007] According to the method for producing conductive composites of the present invention, it is possible to produce conductive composites suitable for the manufacture of paints in which viscosity increase during storage is reduced and the conductivity of the coating film after curing is also good. In the capacitor manufacturing method of the present invention, the above-mentioned excellent conductive composite is manufactured, and a capacitor is manufactured using a conductive polymer dispersion containing this composite. Therefore, a high-performance capacitor reflecting the excellent conductivity of the conductive composite can be manufactured. Furthermore, the conductive polymer dispersion, which is the material for the coating, does not need to be prepared immediately before application; it can be used even if it was prepared several weeks in advance, as the viscosity increase is minimal. This significantly increases the manufacturing efficiency of the capacitor.

[0008] This invention is believed to contribute to SDG Goal 12, "Responsible Consumption and Production."

[0009] In this specification and the claims, the lower and upper limits of the numerical ranges indicated by "~" are to be included within those numerical ranges. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view showing one embodiment of the capacitor of the present invention. [Modes for carrying out the invention]

[0011] ≪Method for manufacturing conductive composites≫ A first aspect of the present invention is a method for manufacturing a conductive composite comprising the following steps A and B. Step A is a step in which a water-soluble azo polymerization initiator is added to a first reaction solution containing a polymerizable anionic monomer and water to obtain a second reaction solution containing a polyanion formed by the polymerization of the polymerizable anionic monomer. Step B is a step in which a polymerizable monomer for forming a π-conjugated conductive polymer and an optional radical polymerization initiator are added to the second reaction solution to form the π-conjugated conductive polymer, thereby obtaining a third reaction solution containing a conductive composite in which the π-conjugated conductive polymer and the polyanion are combined. Each step will be described in detail below.

[0012] <Process A> (polymerizable anionic monomer) Polymerizable anionic monomers are organic compounds that form polyanions upon polymerization and have at least one anionic group in each molecule. The anionic group is a functional group that can ionize in water and may form salts with cations such as sodium or potassium. The polymerizable anionic monomer used in this process is preferably one or more selected from known monomers capable of forming the polyanions exemplified below. Among these, styrene sulfonic acid or a salt thereof, which can form polystyrene sulfonic acid, which is particularly excellent as a dopant for π-conjugated conductive polymers, is most preferred.

[0013] (Polyanion) A polyanion is a polymer that has two or more monomer units containing anionic groups within its molecule. The anionic groups of this polyanion function as dopants for π-conjugated conductive polymers, thereby improving the conductivity of the π-conjugated conductive polymer. The anionic group of the polyanion is preferably a sulfo group or a carboxyl group. Specific examples of such polyanions include polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylic acid esters having sulfo groups, polymethacrylic acid esters having sulfo groups (for example, poly(4-sulfobutyl methacrylate, polysulfoethyl methacrylate, polymethacryloyloxybenzene sulfonic acid), poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and other polymers having sulfo groups, as well as polymers having carboxyl groups such as polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacrylic acid, polymethacrylic acid, poly(2-acrylamido-2-methylpropanecarboxylic acid), and polyisoprene carboxylic acid. Polyanions may be homopolymers formed by the polymerization of a single monomer, or copolymers formed by the polymerization of two or more monomers. Among these polyanions, polymers having sulfo groups are preferred because they can achieve higher conductivity, and polystyrene sulfonic acid is even more preferred.

[0014] (Water-soluble azo polymerization initiator) Examples of the water-soluble azo polymerization initiator used in this step include azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-diaminopropane) hydrochloride, 4,4'-azobis(4-cyanovaleric acid) (commonly known as V-501), 2,2'-azobis(2-methylpropionamidine), 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine], 2,2'-azobis[2-(2-imidazolin-2-yl)propane] (commonly known as VA-046B), 2,2'-azobis(1-imino-1-pyrrolidin-2-methylpropane), 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], and the like.

[0015] The water-soluble azo polymerization initiator may form salts such as hydrochloride, sulfate, ammonium salt, etc., or may be a hydrate. It is preferable to be a salt or a hydrate because the water solubility is increased. For example, VA-046B can form salts with anions such as sulfuric acid, acetic acid, hydrochloric acid, and nitric acid. Also, V-501 can form salts with cations such as Na ions, K ions, and ammonium. Before adding to the first reaction solution, the water-soluble azo polymerization initiator may be reacted with an acid component or an alkali component to form a salt in advance. The solubility of the water-soluble azo polymerization initiator added to the first reaction solution with respect to 100 g of water is preferably 1 g or more, more preferably 5 g or more, and even more preferably 10 g or more.

[0016] (Preparation of reaction solution) The first reaction solution in this step contains a polymerizable anion monomer and water. The polymerizable anion monomer may be one kind or two or more kinds. The content of the polymerizable anion monomer contained in the total mass of the first reaction solution is preferably, for example, 1.0 to 10.0% by mass, more preferably 2.0 to 8.0% by mass, and even more preferably 3.0 to 6.0% by mass. When it is above the lower limit value of the above range, the yield per reaction increases and the production efficiency is improved. If the value is below the upper limit of the above range, the amount of unpolymerized polymerizable anionic monomer remaining at the end of the reaction can be reduced. When two or more polymerizable anionic monomers are added to the first reaction solution, the total amount of each monomer added is within the above range.

[0017] Two methods for adding a water-soluble azo polymerization initiator to the first reaction solution are exemplified below. The first method involves adding the total amount required for the reaction to be completed in multiple portions, gradually and sequentially over a desired period of time (sequential addition method). The second method involves adding the total amount required for the reaction to be completed in one go (one-time addition method).

[0018] The total amount of water-soluble azo polymerization initiation required to complete the polymerization reaction in the first reaction solution is preferably 1 to 30 parts by mass, more preferably 3 to 25 parts by mass, even more preferably 5 to 20 parts by mass, and particularly preferably 7 to 12 parts by mass, per 100 parts by mass of polymerizable anionic monomer contained in the first reaction solution. Within the above range, it is theoretically or empirically sufficient for the purpose of polymerizing almost all polymerizable anionic monomers to form polyanions.

[0019] The amount of water-soluble azo polymerization initiator added to the first reaction solution is preferably 0.05 to 1.00% by mass, more preferably 0.10 to 0.80% by mass, even more preferably 0.20 to 0.70% by mass, and particularly preferably 0.30 to 0.60% by mass, based on the total mass of the reaction solution after all of the water-soluble azo polymerization initiator has been added. Within the above range, it is theoretically or empirically sufficient for the purpose of polymerizing almost all polymerizable anionic monomers and forming the desired polyanions.

[0020] In step A, it is preferable to prepare the entire amount of the water-soluble azo polymerization initiator to be added beforehand as an aqueous solution and gradually add it dropwise over a period of 0.5 hours or more. The dripping time is preferably 0.5 to 8 hours, more preferably 1 to 6 hours, and even more preferably 2 to 4 hours. With the sequential addition method described above, it is less likely that the polymerization chain will react with other radical species during growth and halt the polymerization reaction, and the polymerizable anionic monomer will be consumed more easily. In other words, the amount of radical species generated in the reaction solution can be suppressed, and the amount of unpolymerized polymerizable anionic monomer remaining when all of the water-soluble azo polymerization initiator has been consumed and decomposed (when the polymerization reaction is complete) can be reduced.

[0021] In step A, it is preferable to add the entire amount of water-soluble azo polymerization initiator to obtain the second reaction solution after the polymerization reaction has finished, then obtain the second reaction solution after the polymerization reaction has finished, and subsequently remove the unpolymerized polymerizable anion monomer contained in the second reaction solution by contacting it with an anion exchange resin, and then provide the purified second reaction solution to the subsequent step B. With the above-described batch addition method, a significant amount of unpolymerized polymerizable anionic monomer may remain in the second reaction solution after the polymerization reaction is complete. Therefore, it is preferable to purify the second reaction solution to remove at least a portion of the unpolymerized polymerizable anionic monomer before providing it to the subsequent step B.

[0022] Methods for removing polymerizable anionic monomers from the second reaction solution and purifying them include, for example, ultrafiltration and anion exchange resin adsorption. In ultrafiltration, low molecular weight polymerizable anion monomers permeate the ultrafiltration membrane, while polyanions do not, thus allowing for the separation of the two. In the anion exchange resin adsorption method, if an anion exchange resin that preferentially binds to low molecular weight polymerizable anion monomers is used, the monomers will be adsorbed while polyanions will hardly be adsorbed, thus separating the two. An example of such an anion exchange resin is Duolite C255LFH manufactured by Sumika Chemtex.

[0023] When the water-soluble azo polymerization initiator used in step A is 2,2'-azobis[2-(2-imidazolin-2-yl)propane] (commonly known as VA-046B), the method of addition may be either sequential addition or batch addition, but sequential addition is preferred because it eliminates the need for the above-mentioned purification of unpolymerized polymerizable anion monomers.

[0024] If the method of adding the water-soluble azo polymerization initiator in step A is a single-addition method, then 4,4'-azobis(4-cyanovaleric acid) (commonly known as V-501) is preferred as the water-soluble azo polymerization initiator because it is less likely that unpolymerized polymerizable anionic monomers will remain, and the above purification is unnecessary.

[0025] The completion of the polyanion polymerization reaction in step A is indicated by the consumption of all the water-soluble azo polymerization initiator added to the first reaction solution and the consumption of all radical species. For example, if the reaction is carried out with stirring at 70-95°C, the reaction may be completed in about 4-12 hours.

[0026] The weight-average molecular weight (Mw) of the polyanion contained in the second reaction solution obtained after the completion of the reaction in step A is preferably 20,000 to 1,000,000, more preferably 70,000 to 700,000, and even more preferably 100,000 to 400,000. Here, Mw is the average molecular weight on a mass basis, measured using gel permeation chromatography (GPC) and calculated in terms of pullulan. When the value is above the lower limit of the above range, the function of the π-conjugated conductive polymer as a dopant is enhanced, improving the conductivity of the conductive composite. If the viscosity is below the upper limit of the above range, the viscosity of the conductive polymer dispersion containing the conductive composite will not become excessively high, making it easier to obtain a paint suitable for application.

[0027] <Process B> It is preferable that the second reaction solution used as a material in this process substantially does not contain unpolymerized polymerizable anionic monomers. This is because if a π-conjugated conductive polymer is synthesized in the presence of unpolymerized polymerizable anionic monomers, a conductive composite with inferior conductivity will be formed. The detailed mechanism of this is not yet understood, but it is thought that the occurrence of side reactions is one of the causes.

[0028] The amount of unpolymerized polymerizable anion monomer in the second reaction solution can be analyzed using a gel permeation chromatography (GPC) system. When a portion of the second reaction solution is subjected to GPC as a sample, the polyanions and unpolymerized monomers separate and elute from the column at different or shifted retention times. The amount of compound contained in the solution eluted at each retention time is observed as the detection signal intensity of the detector. Examples of detectors that can be used here include differential refractive index detectors (RI detectors), ultraviolet detectors, light scattering detectors, evaporative light scattering detectors, viscosity detectors, and electrical conductivity detectors. Differential refractive index detectors are preferred due to their high reliability and simple instrument configuration. In GPC system analysis, it is common to create a chart with retention time on the x-axis and detection signal intensity on the y-axis. In this chart, the peak of the detection signal intensity of the polyanions and the peak of the detection signal intensity of the remaining unpolymerized monomers, which can be distinguished from the polyanions, can be observed.

[0029] The ratio expressed as Sm / Sp between the peak area Sp of the detection signal intensity corresponding to the polyanion content in the second reaction solution and the peak area Sm of the detection signal intensity corresponding to the polymerizable anion monomer content is preferably 3.0% or less, more preferably 2.0% or less, even more preferably 1.0% or less, particularly preferably 0.5% or less, and most preferably 0%, which is below the detection limit.

[0030] In step B, a third reaction solution containing a conductive composite can be obtained by known methods, except that a second reaction solution with a low content of unpolymerized polymerizable anion monomers is used as the material. In other words, by adding a polymerizable monomer that forms a π-conjugated conductive polymer and an arbitrary radical polymerization initiator to the second reaction solution, a third reaction solution containing a conductive composite formed by the π-conjugated conductive polymer and the polyanion can be obtained.

[0031] The polymerizable monomer that forms the π-conjugated conductive polymer is preferably one or more selected from known monomers that can form the π-conjugated conductive polymer, as exemplified below. Among these, 3,4-ethylenedioxythiophene, which can form PEDOT with excellent conductivity and heat resistance, is most preferred.

[0032] (π-conjugated conductive polymers) Any organic polymer whose main chain is composed of a π-conjugated system can be used as the π-conjugated conductive polymer. Examples include polypyrrole-based conductive polymers, polythiophene-based conductive polymers, polyacetylene-based conductive polymers, polyphenylene-based conductive polymers, polyphenylene-vinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophene-vinylene-based conductive polymers, and copolymers thereof. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophenes, and polyaniline-based conductive polymers are preferred, and from the viewpoint of transparency, polythiophene-based conductive polymers are more preferred.

[0033] Examples of polythiophene-based conductive polymers include polythiophene, poly(3-methylthiophene), poly(3-ethylthiophene), poly(3-propylthiophene), poly(3-butylthiophene), poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-octadecylthiophene), poly(3-bromothiophene), poly(3-chlorothiophene), and poly(3-iodine). Poly(3-Cyanothiophene), Poly(3-Phenylthiophene), Poly(3,4-Dimethylthiophene), Poly(3,4-Dibutylthiophene), Poly(3-Hydroxythiophene), Poly(3-Methoxythiophene), Poly(3-Ethoxythiophene), Poly(3-Butoxythiophene), Poly(3-Hexyloxythiophene), Poly(3-Heptyloxythiophene), Poly(3-Octyloxythiophene), Poly(3-Decyloxythiophene), Poly(3-Dodecyl Poly(3-octadecyloxythiophene), poly(3,4-dihydroxythiophene), poly(3,4-dimethoxythiophene), poly(3,4-diethoxythiophene), poly(3,4-dipropoxythiophene), poly(3,4-dibutoxythiophene), poly(3,4-dihexyloxythiophene), poly(3,4-diheptyloxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-didecyloxythiophene), poly(3,4-di Examples include dodecyloxythiophene, poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,4-butylenedioxythiophene), poly(3-methyl-4-methoxythiophene), poly(3-methyl-4-ethoxythiophene), poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), and poly(3-methyl-4-carboxybutylthiophene). Examples of polypyrrole-based conductive polymers include polypyrrole, poly(N-methylpyrrole), poly(3-methylpyrrole), poly(3-ethylpyrrole), poly(3-n-propylpyrrole), poly(3-butylpyrrole), poly(3-octylpyrrole), poly(3-decylpyrrole), poly(3-dodecylpyrrole), poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole), poly(3-carboxypyrrole), poly(3-methyl-4-carboxypyrrole), poly(3-methyl-4-carboxyethylpyrrole), poly(3-methyl-4-carboxybutylpyrrole), poly(3-hydroxypyrrole), poly(3-methoxypyrrole), poly(3-ethoxypyrrole), poly(3-butoxypyrrole), poly(3-hexyloxypyrrole), and poly(3-methyl-4-hexyloxypyrrole). Examples of polyaniline-based conductive polymers include polyaniline, poly(2-methylaniline), poly(3-isobutylaniline), poly(2-anilinesulfonic acid), and poly(3-anilinesulfonic acid). Among these π-conjugated conductive polymers, poly(3,4-ethylenedioxythiophene) is particularly preferred in terms of conductivity, transparency, and heat resistance. The π-conjugated conductive polymer formed in step B may be one type or two or more types.

[0034] (Radical polymerization initiator) The radical polymerization initiator used in step B can be arbitrarily selected from known ones and include peroxides such as hydrogen peroxide and t-butyl hydroperoxide; persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate; the aforementioned water-soluble azo polymerization initiators; organic peroxides such as benzoyl peroxide, lauroyl peroxide, peracetic acid, di-t-butyl peroxide, and cumene hydroperoxide; and redox initiators that generate radicals by combining an oxidizing agent and a reducing agent, such as ascorbic acid and hydrogen peroxide, sodium sulfoxylate and t-butyl hydroperoxide, and persulfates and metal salts. Examples of metal salts (catalysts) for redox initiators include transition metal compounds such as ferric chloride, ferric sulfate, ferric nitrate, and cupric chloride. Examples of oxidizing agents for redox initiators include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate.

[0035] (Preparation of reaction solution) The polyanion content relative to the total mass of the second reaction solution in this process can be, for example, 1 to 10% by mass. The ratio of polymerizable monomers and polyanions that form a π-conjugated conductive polymer in the second reaction solution of this process is preferably 1 to 1,000 parts by mass, more preferably 10 to 700 parts by mass, and even more preferably 100 to 500 parts by mass of polyanions per 100 parts by mass of polymerizable monomer. When the value is above the lower limit of the above range, the doping effect of the polyanion increases, making it easier to obtain conductive composites with excellent conductivity. If the value is below the upper limit of the above range, the composite conductive composite will contain a sufficient amount of π-conjugated conductive polymer, making it easier to obtain a conductive composite with excellent conductivity.

[0036] The method of adding the radical polymerization initiator to the second reaction solution in step B is not particularly limited and may be done sequentially or all at once. The amount of radical polymerization initiator added to the second reaction solution in step B can be the same as in the conventional synthesis of π-conjugated conductive polymers, for example, 0.01 to 2.0% by mass relative to the total mass of the reaction solution.

[0037] The completion of the polymerization reaction of the π-conjugated conductive polymer in step B is indicated by the consumption of all the radical polymerization initiator added to the second reaction solution and the consumption of all the radical species. For example, if the reaction is carried out at 15-30°C with stirring, the reaction may be completed in about 6-30 hours.

[0038] A third reaction solution is obtained in which polyanions spontaneously dope the π-conjugated conductive polymer formed by radical polymerization, resulting in the formation of a conductive composite. In polyanions within conductive composites, not all anionic groups are doped into the π-conjugated conductive polymer; there are excess anionic groups that do not participate in doping. These excess anionic groups are hydrophilic, and the dispersibility of conductive composites without anionic group modification is high in aqueous dispersion media and low in organic solvents. In this specification, the terms "dispersed state" and "dissolved state" are not particularly distinguished, and the state in which the conductive composite is dispersed in a liquid medium may be referred to as the dissolved state.

[0039] The third reaction solution obtained in step B contains water and a conductive composite. Residues of the radical polymerization initiator and catalyst may be removed, if necessary, by conventional methods such as ultrafiltration, ion exchange resin adsorption, or gel permeation chromatography to obtain a purified third reaction solution.

[0040] Capacitor manufacturing method A second aspect of the present invention is a method for manufacturing a capacitor using a conductive composite obtained by the manufacturing method of the first aspect as a material. The manufacturing method of this embodiment preferably comprises the steps of: obtaining a conductive composite by the manufacturing method of the first embodiment; preparing a conductive polymer dispersion containing the conductive composite; and applying the conductive polymer dispersion to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal, and drying it to form a solid electrolyte layer.

[0041] The manufacturing method in this embodiment preferably includes the steps of: oxidizing the surface of an anode made of a porous valve metal to form a dielectric layer (dielectric formation step); arranging a cathode at a position opposite the dielectric layer (cathode formation step); and forming a solid electrolyte layer on at least a part of the surface of the dielectric layer (film formation step). Each step will be described below with reference to Figure 1.

[0042] [Dielectric Formation Process] In this process, the surface of the anode 11, which is made of a porous valve metal, is oxidized to form a dielectric layer 12. The method for forming the dielectric layer 12 is not particularly limited, and examples include anodic oxidation of the surface of the anode 11 in an electrolyte solution for chemical treatment, such as an aqueous solution of ammonium adipate, an aqueous solution of ammonium borate, or an aqueous solution of ammonium phosphate.

[0043] [Cathode formation process] In this process, a cathode 13 is placed opposite the dielectric layer 12. The method of arranging the cathode 13 is not particularly limited, and examples include forming the cathode 13 using a conductive paste such as carbon paste or silver paste, or arranging a metal foil such as aluminum foil opposite the dielectric layer 12.

[0044] [Film forming process] In this process, a solid electrolyte layer 14 is formed by applying a conductive polymer dispersion, described later, to at least a portion of the surface of the dielectric layer 12 and drying it.

[0045] Methods for applying the conductive polymer dispersion include, for example, dip coating, comma coating, reverse coating, lip coating, and microgravure coating. Of these, the method of immersing the anode 11 in the conductive polymer dispersion under reduced pressure is preferred. With the dip method, the conductive polymer dispersion can be sufficiently applied to the interior of the porous structure on the surface of the dielectric layer 12. After immersion, it is removed and the drying process is carried out.

[0046] Drying methods include, for example, room temperature drying, hot air drying, and far-infrared drying. Among these, hot air drying is preferred. The drying temperature is preferably 100 to 180°C, and more preferably 120 to 150°C. The drying time is preferably 0.2 to 1 hour. After drying, the capacitor can be assembled using conventional methods.

[0047] <Conductive polymer dispersion> The conductive polymer dispersion used in the film formation process of this embodiment includes a conductive composite obtained by the manufacturing method of the first embodiment and a dispersion medium for dispersing the conductive composite.

[0048] The conductive polymer dispersion used in the film formation process of this embodiment may be one that has been stored for two weeks or more after its preparation. This is because, since it contains the conductive composite obtained by the manufacturing method of the first embodiment, the ratio of the increase in viscosity value after storage for two weeks or more relative to the viscosity value immediately after preparation of the conductive polymer dispersion (initial value) is reduced.

[0049] The content of the conductive composite relative to the total mass of the conductive polymer dispersion is preferably, for example, 0.1 to 3.0% by mass, more preferably 0.5 to 2.5% by mass, and even more preferably 0.8 to 2.0% by mass. Capacitor performance improves when the value is above the lower limit of the above range. If the value is below the upper limit of the above range, the dispersibility of the conductive composite increases.

[0050] (dispersion medium) The dispersion medium constituting the conductive polymer dispersion is not particularly limited as long as it is a liquid capable of dispersing the conductive composite, and examples include water, an organic solvent, or a mixture of water and an organic solvent. Since the conductive composite has excess anionic groups derived from polyanions and has high dispersibility in water, an aqueous dispersion medium is preferred. Here, the aqueous dispersion medium is water, or a mixture of water and a water-soluble organic solvent. The water-soluble organic solvent is an organic solvent whose solubility in 100 g of water at 20°C is 1 g or more, and examples include alcohol-based solvents, ketone-based solvents, and ester-based solvents. The aqueous dispersion medium may contain one or more water-soluble organic solvents.

[0051] The water content relative to the total mass of the dispersion medium is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more.

[0052] Examples of alcohol-based solvents include methanol, ethanol, isopropanol, n-butanol, t-butanol, and allyl alcohol. Examples of ketone solvents include diethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisopropyl ketone, methyl ethyl ketone, acetone, and diacetone alcohol. Examples of ester solvents include ethyl acetate, propyl acetate, and butyl acetate.

[0053] It is preferable to add one or more polyol compounds to the conductive polymer dispersion. The solid electrolyte layer can contain the polyol compound, thereby improving the capacitor performance. Here, the polyol compound is a compound other than a π-conjugated conductive polymer and a polyanion, and is a compound having two or more hydroxyl groups. Specific examples of polyol compounds include one or more selected from ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, glycerin, pentaerythritol, trimethylolpropane, and trimethylolethane.

[0054] The amount of polyol compound contained in the conductive polymer dispersion is preferably, for example, 100 parts by mass or more and 10,000 parts by mass or less, more preferably 200 parts by mass or more and 2,000 parts by mass or less, and even more preferably 300 parts by mass or more and 1,000 parts by mass or less, based on 100 parts by mass of the total of the π-conjugated conductive polymer and polyanion (i.e., 100 parts by mass of the conductive composite). Within the above range, the ESR of the capacitor tends to decrease more easily, which is preferable.

[0055] The conductive polymer dispersion may contain any additives, the proportion of which can be appropriately determined depending on the type of additive, but for example, it can be 1 to 1000 parts by mass per 100 parts by mass of the total of the π-conjugated conductive polymer and polyanion (i.e., 100 parts by mass of the conductive composite). Here, the optional additive is a compound other than the conductive composite, the polyol compound, and the dispersion medium.

[0056] Optional additives include, for example, surfactants, inorganic conductive agents, defoamers, coupling agents, antioxidants, and UV absorbers. Examples of surfactants include nonionic, anionic, and cationic surfactants, but nonionic surfactants are preferred in terms of storage stability. Polymer-based surfactants such as polyvinyl alcohol and polyvinylpyrrolidone may also be added. Examples of inorganic conductive agents include metal ions and conductive carbon. Metal ions can be generated by dissolving metal salts in water. Examples of defoaming agents include silicone resins, polydimethylsiloxanes, and silicone oils. Examples of coupling agents include silane coupling agents having vinyl groups, amino groups, epoxy groups, etc. Examples of antioxidants include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, and sugars. Examples of UV absorbers include benzotriazole-based UV absorbers, benzophenone-based UV absorbers, salicylate-based UV absorbers, cyanoacrylate-based UV absorbers, oxanilide-based UV absorbers, hindered amine-based UV absorbers, and benzoate-based UV absorbers. [Examples]

[0057] (Manufacturing Example 1) Production of polystyrene sulfonic acid 1; used in Example 1 55 g of sodium styrene sulfonate was dissolved in 899 ml of deionized water. While stirring at 80°C, an aqueous solution of 6.0 g of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] (commonly known as VA-046B), which had been previously dissolved in 40 ml of water, was gradually added dropwise at a constant rate over 2 hours, and the solution was stirred for another 4 hours. The resulting sodium polystyrene sulfonate-containing solution was brought into contact with a cation exchange resin (Sumika Chemtex Co., Ltd., Duolite C255LFH) to remove sodium ions. The solid content (non-volatile component) of the resulting polystyrene sulfonic acid (PSS) aqueous solution was 5% by mass.

[0058] The PSS aqueous solution obtained above was analyzed using gel permeation chromatography (GPC) with pullulan of a known weight-average molecular weight manufactured by Showa Denko K.K. as a standard substance. As a result, the weight-average molecular weight (Mw) was found to be 675,000. Furthermore, during the GPC measurement, a differential refractive index detector was used, and the peak area Sp of PSS and the peak area Sm of unpolymerized styrene sulfonic acid monomer, which appeared on a chart showing the signal intensity of the differential refractive index on the vertical axis and the retention time on the horizontal axis, were analyzed, and the calculated ratio (Sm / Sp) was 0%. This ratio value means that virtually no unpolymerized monomer remains.

[0059] The above GPC system measurements were performed using a Prominence high-performance liquid chromatograph manufactured by Shimadzu Corporation. A 0.1% NaNO3 aqueous solution was used as the solvent, a Shodex OHpack SB-806M HQ column was used, and a differential refractive index detector RID-20A was used as the detector. The solvent temperature was set to 40°C, the flow rate to 0.6 ml / min, and 100 μl of the sample, which had been diluted to a PSS concentration of 0.1 mass%, filtered through a 0.2 μm pore size membrane filter, was injected. Analysis was then performed using Lab Solutions software (Shimadzu Corporation).

[0060] (Manufacturing Example 2) Production of polystyrene sulfonic acid 2; used in Example 2 The preparation of the sodium styrenesulfonate aqueous solution was carried out in the same manner as in Production Example 1, except that 27.5 g of sodium styrenesulfonate was dissolved in 926.5 ml of deionized water. The solid content (non-volatile component) of the obtained PSS aqueous solution was 2.6% by mass. The GPC analysis revealed that Mw was 338,000, and the ratio (Sm / Sp) was 0%.

[0061] (Manufacturing Example 3) Production of polystyrene sulfonic acid 3; used in Comparative Example 1 The procedure was the same as in Production Example 2, except that the entire volume of VA-046B aqueous solution was added all at once to initiate polymerization, rather than adding it dropwise. The solid content (non-volatile component) of the obtained PSS aqueous solution was 2.6% by mass. GPC analysis revealed a Mw of 33,000 and a ratio (Sm / Sp) of 3.3%. This ratio indicates that unpolymerized monomers definitely remain.

[0062] (Manufacturing Example 4) Production of polystyrene sulfonic acid 4; used in Comparative Example 2 The preparation of the sodium styrenesulfonate aqueous solution was carried out in the same manner as in Production Example 3, except that 27.5 g of sodium styrenesulfonate was dissolved in 930.5 ml of deionized water, and the amount of VA-046B dissolved was changed to 2.0 g when preparing the VA-046B aqueous solution. The solid content (non-volatile component) of the obtained PSS aqueous solution was 2.6% by mass. The GPC analysis revealed that Mw was 73,000, and the ratio (Sm / Sp) was 4.0%.

[0063] (Manufacturing Example 5) Manufacturing of polystyrene sulfonic acid 5; used in Comparative Example 3 The preparation of the sodium styrenesulfonate aqueous solution was carried out in the same manner as in Production Example 3, except that 27.5 g of sodium styrenesulfonate was dissolved in 931.0 ml of deionized water, and the amount of VA-046B dissolved was changed to 1.5 g when preparing the VA-046B aqueous solution. The solid content (non-volatile component) of the obtained PSS aqueous solution was 2.6% by mass. The GPC analysis revealed that Mw was 105,000, and the ratio (Sm / Sp) was 4.3%.

[0064] (Manufacturing Example 6) Production of polystyrene sulfonic acid 6; used in Comparative Example 4 The preparation of the sodium styrenesulfonate aqueous solution was carried out in the same manner as in Production Example 3, except that 27.5 g of sodium styrenesulfonate was dissolved in 931.5 ml of deionized water, and the amount of VA-046B dissolved was changed to 1.0 g when preparing the VA-046B aqueous solution. The solid content (non-volatile component) of the obtained PSS aqueous solution was 2.6% by mass. The GPC analysis revealed that Mw was 134,000, and the ratio (Sm / Sp) was 7.5%.

[0065] (Manufacturing Example 7) Manufacturing of polystyrene sulfonic acid 7; used in Example 3 The preparation of the sodium styrenesulfonate aqueous solution was carried out in the same manner as in Production Example 3, except that 27.5 g of sodium styrenesulfonate was dissolved in 929.5 ml of deionized water, and an aqueous solution containing 3.0 g of 4,4'-azobis(4-cyanovaleric acid) (commonly known as V-501) was used instead of VA-046B. The solid content (non-volatile component) of the obtained PSS aqueous solution was 2.6% by mass. The GPC analysis revealed that Mw was 218,000, and the ratio (Sm / Sp) was 0%. These results indicate that when using V-501, unpolymerized monomers are less likely to form even when the entire amount of initiator is added to the reaction solution at once.

[0066] (Manufacturing Example 8) Production of polystyrene sulfonic acid 8; used in Example 4 The procedure was carried out in the same manner as in Production Example 7, except that the temperature of the reaction solution was changed to 90°C. The solid content (non-volatile component) of the obtained PSS aqueous solution was 2.6% by mass. The GPC analysis revealed that Mw was 134,000, and the ratio (Sm / Sp) was 0%.

[0067] (Manufacturing Example 9) Production of polystyrene sulfonic acid 9; used in Comparative Example 5 110 g of sodium styrene sulfonate was dissolved in 820 ml of deionized water. While stirring at 80°C, the entire amount of 8.54 g of sodium peroxodisulfate, which had been previously dissolved in 55 ml of water, was added all at once and gradually added dropwise at a constant rate over 2 hours. The solution was then stirred for 6 hours. A cation exchange resin was added to the resulting sodium polystyrene sulfonate-containing solution to remove sodium ions. The solid content (non-volatile component) of the obtained PSS aqueous solution was 10% by mass. The GPC analysis revealed that Mw was 105,000, and the ratio (Sm / Sp) was 0%.

[0068] (Manufacturing Example 10) Manufacturing of polystyrene sulfonic acid 10; used in Example 5 First, an aqueous PSS solution was obtained in the same manner as in Production Example 4. Next, this aqueous PSS solution was brought into contact with an anion exchange resin (Duolite A368MS, manufactured by Sumika Chemtex Co., Ltd.) to remove unpolymerized styrene sulfonic acid. The solid content (non-volatile components) of the purified PSS aqueous solution was 2.3% by mass. When this was analyzed using a GPC system, similar to manufacturing example 1, the Mw was 80,000 and the ratio (Sm / Sp) was 0%.

[0069] (Manufacturing Example 11) Manufacturing of polystyrene sulfonic acid 11; used in Example 6 First, an aqueous PSS solution was obtained in the same manner as in Production Example 5. Next, this aqueous PSS solution was purified in the same manner as in Production Example 10 to remove unpolymerized styrene sulfonic acid. The solid content (non-volatile components) of the purified PSS aqueous solution was 2.3% by mass. When this was analyzed using a GPC system, similar to manufacturing example 1, the Mw was 112,000 and the ratio (Sm / Sp) was 0%.

[0070] [Example 1] (Manufacturing of PEDOT-PSS aqueous dispersion) 5.71 g of 3,4-ethylenedioxythiophene, 282.5 g of an aqueous solution of polystyrene sulfonic acid obtained in Production Example 1, and 605.25 g of deionized water were mixed at 20°C. The resulting mixture was kept at 20°C and stirred while adding 1.60 g of ferric sulfate oxidation catalyst solution dissolved in 26.65 g of deionized water. 8.68 g of sodium peroxodisulfate dissolved in 78.9 g of deionized water was gradually added dropwise at a constant rate over 2 hours, and the mixture was stirred for a further 4 hours to allow the reaction to proceed. A cation exchange resin (Duolite C255LFH, manufactured by Sumika Chemtex Co., Ltd.) and an anion exchange resin (Duolite A368S, manufactured by Sumika Chemtex Co., Ltd.) were added to the resulting reaction solution to remove the polymerization initiator and iron. This yielded a blue PEDOT-PSS aqueous dispersion with a PEDOT:PSS ratio of 1:2.5 (mass ratio). The solid content (non-volatile components) of the obtained dispersion was adjusted to 1.6% by mass by ultrafiltration.

[0071] (Conductivity evaluation) 1.9 g of the PEDOT-PSS aqueous dispersion obtained above, 4 g of methanol, and 0.1 g of propylene glycol were mixed together, and the resulting coating was applied to a PET film (Toray Industries, Inc., Lumirror T60) using a #12 bar coater. The mixture was dried at 120°C for 1 minute to obtain a conductive film with a conductive layer formed on its surface. The surface resistance was measured using a resistivity meter (Highresta, manufactured by Mitsubishi Chemical Analytec Co., Ltd.) with an applied voltage of 10V. The measurement results are shown in the table. A smaller surface resistance value (unit: Ω / □) indicates higher conductivity.

[0072] (viscosity measurement) The PEDOT-PSS aqueous dispersion obtained above was dispersed using a high-pressure homogenizer. A portion of this dispersion was then taken and measured at 25°C in accordance with JIS Z8803:2011 (Method for measuring viscosity using a vibrating viscometer) using a tuning fork vibrating viscometer (model: SV-10, manufactured by A&D Co., Ltd.). The remaining dispersion was placed in a sealed bottle and stored at 5-10°C for two weeks. The stored PEDOT-PSS aqueous dispersion was returned to 25°C, and its viscosity was measured using the same method as above. The measurement results for each viscosity are shown in the table. In the table, 1 Pa·s (Pascal-second) was used for conversion to 1000 cP (centipoise).

[0073] [Example 2] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 1, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 2 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0074] [Example 3] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 2, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 7 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0075] [Example 4] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 2, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 8 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0076] [Example 5] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 1, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 10 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0077] [Example 6] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 5, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 11 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0078] [Comparative Example 1] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 1, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 3 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0079] [Comparative Example 2] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 1, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 4 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0080] [Comparative Example 3] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 1, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 5 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0081] [Comparative Example 4] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 1, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 6 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0082] [Comparative Example 5] A conductive polymer dispersion was prepared and evaluated in the same manner as in Example 1, except that the aqueous polystyrene sulfonic acid solution obtained in Production Example 9 was used and the amount of water was adjusted to achieve a mass ratio of 3,4-ethylenedioxythiophene:PSS = 1:2.5. The results are shown in Table 2.

[0083] [Table 1]

[0084] [Table 2]

[0085] The conductive polymer dispersions containing the conductive composites obtained by the manufacturing methods in Examples 1 to 6 were able to form a conductive layer with excellent conductivity and also exhibited excellent storage stability. This is because the reaction solution used to form the conductive composite in step B contained substantially no unpolymerized polymerizable anionic monomers. In Examples 1 and 2, the water-soluble azo polymerization initiator VA-046B was gradually added dropwise in step A, so all of the polymerizable anionic monomers reacted. In Examples 3 and 4, since the water-soluble azo polymerization initiator V-501 was used in step A, all of the polymerizable anionic monomers reacted. In Examples 5 and 6, the entire amount of the water-soluble azo polymerization initiator VA-046B was added in one step A, resulting in unpolymerized polymerizable anionic monomers remaining at the end of the reaction. However, these polymerizable anionic monomers were removed and purified using an anion exchange resin before being subjected to step B, so no polymerizable anionic monomers were introduced into step B. In the manufacturing methods of Comparative Examples 1 to 4, the entire amount of the water-soluble azo polymerization initiator VA-046B was added at once in step A, resulting in unpolymerized polymerizable anion monomers remaining at the end of the reaction. These were carried over to step B, and as a result, the conductive polymer dispersion containing the manufactured conductive composite was inferior in terms of conductivity. In the manufacturing method of Comparative Example 5, which is a conventional manufacturing method, a water-soluble azo polymerization initiator was not used in step A (manufacturing example 9), but sodium peroxodisulfate was used instead. Although no unpolymerized polymerizable anionic monomers remained, the viscosity of the conductive polymer dispersion containing the conductive composite obtained in step B increased significantly during storage, resulting in poor storage stability and poor usability. [Explanation of Symbols]

[0086] 10 Capacitors 11 Anode 12 Dielectric layer 13 Cathode 14 Solid electrolyte layer

Claims

1. Step A involves adding a water-soluble azo polymerization initiator to a first reaction solution containing a polymerizable anionic monomer and water to obtain a second reaction solution containing a polyanion formed by the polymerization of the polymerizable anionic monomer, and A method for producing a conductive composite, comprising step B, of adding a polymerizable monomer that forms a π-conjugated conductive polymer and an optional radical polymerization initiator to the second reaction solution to form the π-conjugated conductive polymer, thereby obtaining a third reaction solution containing a conductive composite in which the π-conjugated conductive polymer and the polyanion are complexed, The second reaction solution to be subjected to step B is analyzed in advance using a gel permeation chromatography system. A method for producing a conductive composite, comprising confirming that the ratio expressed as Sm / Sp of the peak area Sp of the detection signal intensity corresponding to the polyanion content and the peak area Sm of the detection signal intensity corresponding to the polymerizable anion monomer content is 3.0% or less, and then supplying the second reaction solution to step B.

2. The method for producing a conductive composite according to claim 1, wherein in step A, the entire amount of the water-soluble azo polymerization initiator to be added until the second reaction solution in which the polymerization reaction has been completed is prepared in advance as an aqueous solution and gradually added dropwise over a period of 0.5 hours or more.

3. A method for producing a conductive composite according to claim 1, wherein in step A, the entire amount of the water-soluble azo polymerization initiator to be added until the second reaction solution in which the polymerization reaction has been completed is obtained is added all at once, and thereafter the second reaction solution in which the polymerization reaction has been completed is obtained, and subsequently the unpolymerized polymerizable anion monomer contained in the second reaction solution is removed by contacting it with an anion exchange resin, and the purified second reaction solution is subjected to the subsequent step B.

4. A method for producing a conductive composite according to any one of claims 1 to 3, wherein the water-soluble azo polymerization initiator used in step A is 2,2'-azobis[2-(2-imidazolin-2-yl)propane].

5. Step A, comprising adding a water-soluble azo polymerization initiator to a first reaction solution containing a polymerizable anionic monomer and water, to obtain a second reaction solution containing a polyanion formed by polymerization of the polymerizable anionic monomer, A method for producing a conductive composite, comprising step B, of adding a polymerizable monomer that forms a π-conjugated conductive polymer and an optional radical polymerization initiator to the second reaction solution to form the π-conjugated conductive polymer, thereby obtaining a third reaction solution containing a conductive composite in which the π-conjugated conductive polymer and the polyanion are complexed, When the second reaction solution subjected to step B was analyzed using a gel permeation chromatography system, The ratio expressed as Sm / Sp between the peak area Sp of the detection signal intensity corresponding to the polyanion content and the peak area Sm of the detection signal intensity corresponding to the polymerizable anion monomer content is 3.0% or less. A method for producing a conductive composite, wherein the water-soluble azo polymerization initiator used in step A is 4,4'-azobis(4-cyanovaleric acid) or a salt thereof, the entire amount of the water-soluble azo polymerization initiator to be added until the second reaction solution in which the polymerization reaction is completed is obtained is added all at once, and then the second reaction solution in which the polymerization reaction is completed is obtained and the second reaction solution is subjected to the subsequent step B without being purified by contacting it with an anion exchange resin.

6. The method for producing a conductive composite according to claim 1, wherein the water-soluble azo polymerization initiator added to the first reaction solution in step A forms a salt.

7. The method for producing a conductive composite according to claim 1, wherein the weight-average molecular weight of the polyanion contained in the second reaction solution obtained in step A is 100,000 to 400,000.

8. The method for producing a conductive composite according to claim 1, wherein the polymerizable monomer that forms the π-conjugated conductive polymer is (3,4-ethylenedioxythiophene).

9. The method for producing a conductive composite according to claim 1, wherein the polymerizable anion monomer that forms the polyanion is styrene sulfonic acid or a salt thereof.

10. A step of obtaining a conductive composite by a method for manufacturing a conductive composite according to claim 1 or 5, A step of preparing a conductive polymer dispersion containing the conductive composite, A step of forming a solid electrolyte layer by applying the conductive polymer dispersion to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal and drying it, A method for manufacturing a capacitor, comprising:

Images