Method for producing conductive polymer dispersion liquid, method for producing conductive laminate, and method for producing capacitor

Abstract

To provide a method for producing a conductive polymer dispersion liquid that has adequately low viscosity and exhibits superior conductivity after drying and curing, and to provide a method for producing a conductive laminate and a method for producing a capacitor using the conductive polymer dispersion liquid.SOLUTION: A method for producing a conductive polymer dispersion liquid comprises a step of initiating a polymerization reaction by adding a polymerization initiator that polymerizes a monomer forming a π-conjugated conductive polymer to a reaction liquid containing a polyanion, the monomer forming the π-conjugated conductive polymer, an aqueous dispersion medium, and a catalyst containing a transition metal, thereby forming a conductive composite containing the π-conjugated conductive polymer and the polyanion, wherein an amount of a monovalent cation capable of forming a salt with an anionic group of the polyanion contained in the reaction liquid immediately before addition of the polymerization initiator is 10.0 pts.mass or less per 100 pts.mass of the polyanion.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a conductive polymer dispersion containing a π-conjugated conductive polymer and a polyanion, a method for producing a conductive laminate, and a method for producing a capacitor. [Background technology]

[0002] A π-conjugated conductive polymer whose main chain is composed of a π-conjugated system forms a conductive complex by doping with a polyanion having an anionic group, and becomes dispersible in water. A method for manufacturing a capacitor has been disclosed (for example, Patent Document 1), in which a paint made from a conductive polymer dispersion containing a conductive complex is applied to a dielectric layer provided on the surface of an anode made of a valve metal, dried to form a solid electrolyte layer, and then a cathode is placed opposite this. According to this disclosure, the performance of the capacitor is improved by adding a specific unsaturated aliphatic alcohol compound to the paint. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-071400 Summary of the Invention [Problem to be solved by the invention]

[0004] The conductive polymer dispersion liquid used in the production of capacitors must have low viscosity so that it can penetrate into the porous structure of the dielectric layer, and the solid electrolyte layer formed by drying the soaked conductive polymer dispersion liquid must also have high conductivity.

[0005] The present invention provides a method for producing a conductive polymer dispersion liquid that has a sufficiently low viscosity and excellent conductivity after drying and curing, and a method for producing a conductive laminate and a method for producing a capacitor using the same. [Means for solving the problem]

[0006] [1] A method for producing a conductive polymer dispersion, comprising the step of adding a polymerization initiator that polymerizes a monomer to a reaction liquid containing a polyanion, a monomer that forms a π-conjugated conductive polymer, an aqueous dispersion medium, and a catalyst containing a transition metal to initiate a polymerization reaction, thereby forming a conductive composite that contains the π-conjugated conductive polymer and the polyanion, wherein the amount of monovalent cations that can form a salt with an anion group of the polyanion, contained in the reaction liquid immediately before adding the polymerization initiator, is 10.0 parts by mass or less per 100 parts by mass of the polyanion. [2] The method for producing a conductive polymer dispersion according to [1], wherein an aqueous polyanion solution containing the polyanion to be added to the reaction solution is prepared in advance, and the aqueous polyanion solution is added to the reaction solution after removing the monovalent cations contained in the aqueous polyanion solution. [3] The method for producing a conductive polymer dispersion according to [2], further comprising a preliminary step of polymerizing a monomer that forms the polyanion in the presence of water to obtain the aqueous polyanion solution, wherein an alkali metal salt or ammonium salt of styrenesulfonic acid is used as the monomer in the preliminary step. [4] The method for producing a conductive polymer dispersion according to [3], wherein the content of alkali metal ions and ammonium relative to the total mass of the aqueous polyanion solution obtained in the preliminary step is 1.0 mass% or less after the treatment for removing the monovalent cations. [5] The method for producing a conductive polymer dispersion according to any one of [2] to [4], wherein the monovalent cations contained in the aqueous polyanion solution are removed using an ion exchange resin. [6] The method for producing a conductive polymer dispersion according to any one of [1] to [4], wherein the amount of the monovalent cation contained in the reaction liquid immediately before the addition of the polymerization initiator is 0.150 mass % or less, relative to the total mass of the reaction liquid. [7] The method for producing a conductive polymer dispersion according to any one of [1] to [6], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene). [8] The method for producing a conductive polymer dispersion according to any one of [1] to [7], wherein the polyanion is polystyrene sulfonic acid. [9] A method for producing a conductive laminate, comprising: obtaining a conductive polymer dispersion by the production method according to any one of [1] to [8]; and applying the conductive polymer dispersion to at least a part of the surface of a substrate and drying it to form a conductive layer.

[10] A method for producing a capacitor, comprising: a step of obtaining a conductive polymer dispersion by the production method according to any one of [1] to [8]; and a step of applying the conductive polymer dispersion to a surface of a dielectric layer formed on a surface of an anode made of a porous valve metal, and drying the applied conductive polymer dispersion to form a solid electrolyte layer. [Effects of the Invention]

[0007] According to the present invention, there is provided a method for producing a conductive polymer dispersion liquid that has a sufficiently low viscosity and excellent conductivity after drying and curing. The conductive polymer dispersion liquid produced in this way is suitable for producing conductive laminates and capacitors.

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

[0009] In this specification and claims, the lower and upper limits of numerical ranges indicated with "to" are included in the numerical range. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view illustrating one embodiment of a capacitor. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Method for producing conductive polymer dispersion> A first aspect of the present invention is a method for producing a conductive polymer dispersion, comprising the step of adding a polymerization initiator that polymerizes a monomer to a reaction liquid containing a polyanion, a monomer that forms a π-conjugated conductive polymer, an aqueous dispersion medium, and a catalyst that contains a transition metal, to initiate a polymerization reaction, thereby forming a conductive composite that contains the π-conjugated conductive polymer and the polyanion.

[0012] In this embodiment, the amount of monovalent cations capable of forming salts with the anionic groups of the polyanions contained in the reaction solution immediately before the addition of the polymerization initiator is preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, and even more preferably 5.0 parts by mass or less, relative to 100 parts by mass of the polyanions contained in the reaction solution. Within this range, the conductivity of the conductive layer formed from the conductive polymer dispersion to be produced is increased.

[0013] As a specific example of this embodiment, the following steps A and B can be mentioned.

[0014] <Process A (preliminary process)> In step A, an aqueous polyanion solution is prepared. Step A is a step of adding a polymerization initiator to a first reaction liquid containing a polymerizable anionic monomer and water to obtain a second reaction liquid (aqueous polyanion solution) containing a polyanion formed by polymerization of the polymerizable anionic monomer.

[0015] Polymerizable anionic monomers are organic compounds that form polyanions upon polymerization and contain at least one anionic group per molecule. The anionic group is a functional group that can be ionized in water and may form a salt with an alkali metal ion such as sodium or potassium, or with ammonium. The polymerizable anionic monomer used in this step is preferably one or more selected from known monomers capable of forming polyanions, which will be exemplified later. Among them, styrene sulfonic acid or a salt thereof is most preferred, as it can form polystyrene sulfonic acid, which is particularly excellent as a dopant for π-conjugated conductive polymers. Examples of the salt include alkali metal salts and ammonium salts. The amount of the polymerizable anionic monomer to be mixed relative to the total mass of the first reaction liquid is, for example, preferably 1.0 to 20.0 mass %, more preferably 5.0 to 15.0 mass %, and even more preferably 8.0 to 13.0 mass %. When the amount is at least the lower limit of the above range, the yield per reaction increases, and production efficiency improves. When the content is equal to or less than the upper limit of the above range, the amount of low-molecular-weight polyanions formed can be reduced.

[0016] Examples of the polymerization initiator include persulfates such as ammonium persulfate, sodium persulfate, potassium persulfate, etc. The amount of the polymerization initiator to be added relative to the total mass of the first reaction liquid is, for example, 0.1 to 1.0% by mass.

[0017] The completion of the polymerization reaction of the polyanion in step A is determined when all of the polymerization initiator added to the first reaction solution has been consumed. For example, when the reaction is carried out at 70 to 95°C with stirring, the reaction may be completed in about 4 to 12 hours.

[0018] The second reaction solution contains the formed polyanion. When the anionic group of the polyanion forms a salt with a counter cation, it is preferable to remove the cation by contacting the polyanion with a cation exchange resin. The second reaction solution preferably contains a high molecular weight polyanion polymerized to an Mw of 10,000 or more, preferably 50,000 or more, and more preferably 100,000 or more.

[0019] The second reaction solution may contain monovalent cations derived from the raw materials. From the viewpoint of reducing the amount of monovalent cations carried over into the reaction solution in the subsequent step B, it is preferable to remove the monovalent cations contained in the second reaction solution to obtain an aqueous polyanion solution and then provide this to the reaction solution in step B. By removing the monovalent cations in advance, the monovalent cations that form salts with the anionic groups of the polyanion are removed, and the anionic groups are more likely to function as dopants for the π-conjugated conductive polymer in step B.

[0020] Examples of methods for purifying polyanions by removing monovalent cations from the second reaction solution include ultrafiltration and cation exchange resin adsorption. In ultrafiltration, low molecular weight monovalent cations pass through the ultrafiltration membrane, while high molecular weight polyanions do not, so the two can be separated. In the cation exchange resin adsorption method, low molecular weight monovalent cations are preferentially bound, and high molecular weight polyanions, which are anions, are not adsorbed, so the two can be separated.

[0021] The monovalent cation concentration (e.g., the concentration of alkali metal ions and ammonium) in the aqueous polyanion solution obtained in step A may exceed 1.0 mass % before the treatment to remove the monovalent cations, based on the mass of the aqueous polyanion solution as a whole. In this case, the concentration after the treatment to remove the monovalent cations is preferably 1.0 mass % or less, more preferably 0.60 mass % or less, and even more preferably 0.50 mass % or less. Within this range, the conductivity of the conductive layer formed from the conductive polymer dispersion liquid produced is further increased.

[0022] The monovalent cation concentration in the aqueous polyanion solution or reaction solution can be measured by a known method using ion chromatography or a plasma emission spectrometer. In this case, it is preferable to prepare a calibration curve in advance using standard samples with known monovalent cation concentrations. For example, in the case of sodium ions, the ion concentration can be calculated by measuring using an ICA-2000 (manufactured by DKK-TOA Corporation), a PCI-322 column, and an electrical conductivity detector. Measurements can also be performed using a plasma emission spectrometer iCAP 6500Duo (manufactured by Thermo Fisher Scientific). 0.03 g of sample is weighed into a digitube, and ultrapure water is added to make a 50 mL volume. This is then measured with the plasma emission spectrometer, and the amount of Na is converted to the amount in the sample, which is used as the measured value. In the case of ammonium ions, the ammonium ions are pre-distilled according to JIS K0102 42.1, and then measured by ion chromatography using a Dionex Integrion (Thermo Fisher Scientific) measuring device, a CS16-5.5 μm (5 mmφ, 250 mm) column, and an electrical conductivity detector. The ion concentration can be calculated by measurement.

[0023] <Process B> Next, in step B, a polymerization initiator that polymerizes the monomer is added to a reaction liquid containing a polyanion, a monomer that forms a π-conjugated conductive polymer, an aqueous dispersion medium, and a catalyst containing a transition metal to initiate a polymerization reaction, thereby forming a conductive composite that contains the π-conjugated conductive polymer and the polyanion.

[0024] Step B is preferably a step of adding a polymerizable monomer that forms a π-conjugated conductive polymer, the catalyst, and an arbitrary radical polymerization initiator to the aqueous polyanion solution obtained in Step A, thereby forming the π-conjugated conductive polymer, thereby obtaining a third reaction solution containing a conductive complex in which the π-conjugated conductive polymer and the polyanion are complexed together. The aqueous polyanion solution used in step B may be the one obtained in step A, or may be an aqueous solution prepared by dissolving a commercially available polyanion in water. When the commercially available polyanion contains monovalent cations, it is preferable to remove these cations before use in step B.

[0025] In step B, the third reaction liquid containing the conductive complex can be obtained by a known method, except that the monovalent cation concentration in the reaction liquid immediately before the addition of the polymerization initiator is set to a predetermined value.

[0026] In step B, the amount of monovalent cations contained in the reaction solution immediately before adding the polymerization initiator is preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, and even more preferably 5.0 parts by mass or less, relative to 100 parts by mass of the polyanion contained in the reaction solution. Within this range, the conductivity of the conductive layer formed from the produced conductive polymer dispersion is increased.

[0027] In step B, the amount of monovalent cations contained in the reaction solution immediately before adding the polymerization initiator is preferably 0.150% by mass or less, more preferably 0.100% by mass or less, and even more preferably 0.090% by mass or less, relative to the total mass of the reaction solution. Within this range, the conductivity of the conductive layer formed from the produced conductive polymer dispersion is further increased.

[0028] The polymerizable monomer for forming the π-conjugated conductive polymer is preferably one or more selected from known monomers capable of forming π-conjugated conductive polymers, which will be exemplified later. Among them, 3,4-ethylenedioxythiophene is the most preferred, as it can form PEDOT, which has excellent conductivity and heat resistance.

[0029] The catalyst containing a transition metal is preferably one that decomposes the polymerization initiator to generate radicals. From the viewpoint of enhancing this catalytic action, the catalyst preferably contains an iron compound or a copper compound, more preferably one containing an iron compound. Specific examples include ferric chloride, ferric sulfate, ferric nitrate, ferric citrate, and cupric chloride. The type of catalyst to be blended in the reaction liquid may be one type or two or more types.

[0030] The content of the catalyst relative to the total mass of the reaction liquid immediately before the addition of the polymerization initiator is, for example, preferably 0.01 mass% or more and 0.50 mass% or less, more preferably 0.05 mass% or more and 0.35 mass% or less, and even more preferably 0.10 mass% or more and 0.20 mass% or less. When the content is within the above preferred range, a conductive polymer dispersion liquid in which a conductive composite having excellent conductivity is dispersed can be more easily obtained.

[0031] The polymerization initiator may be any initiator that promotes or initiates polymerization by chemical oxidation of the monomer, and is preferably a radical polymerization initiator that is generally used in the production of polymers. The polymerization initiator is preferably one that decomposes under the action of the catalyst to generate radicals, and preferably one that has a peracid structure represented by "-SO2-OO-" in the molecule. Specifically, peroxodisulfuric acid or a salt thereof, or peroxomonosulfuric acid or a salt thereof is preferred. Here, the salt has a counter cation such as sodium, potassium, or ammonium. Among these, peroxodisulfates (persulfates) are more preferred. The type of polymerization initiator added to the reaction liquid may be one type or two or more types.

[0032] The polymerization initiator is preferably added last to the reaction liquid after all other materials have been mixed. The polymerization initiator is preferably dissolved in a small amount of water and added to the reaction liquid. The polymerization initiator may be added all at once or may be added stepwise. From the viewpoint of stably progressing the polymerization reaction, it is preferable to slowly add a certain amount dropwise over a predetermined period of time (for example, 2 to 4 hours). The dropping method makes it easier to obtain a conductive polymer dispersion in which a conductive complex with excellent conductivity is dispersed.

[0033] The amount of the polymerization initiator added relative to the total mass of the reaction liquid immediately before the addition of the polymerization initiator is preferably 0.10% by mass or more and 1.50% by mass or less, more preferably 0.30% by mass or more and 1.30% by mass or less, and even more preferably 0.50% by mass or more and 1.20% by mass or less. When the content is within the above preferred range, a conductive polymer dispersion liquid in which a conductive composite having excellent conductivity is dispersed can be more easily obtained.

[0034] The content of the monomer relative to the total mass of the reaction liquid immediately before the addition of the polymerization initiator is preferably 0.1 mass% or more and 2.0 mass% or less, more preferably 0.3 mass% or more and 1.5 mass% or less, and even more preferably 0.5 mass% or more and 1.0 mass% or less. When the content is within the above preferred range, a conductive polymer dispersion liquid in which a conductive composite having excellent conductivity is dispersed can be more easily obtained.

[0035] The content of the polyanion relative to the total mass of the reaction solution immediately before the addition of the polymerization initiator is preferably 0.3% by mass or more and 6.0% by mass or less, more preferably 1.0% by mass or more and 3.0% by mass or less, and even more preferably 1.5% by mass or more and 2.0% by mass or less. When the content is within the above preferred range, a conductive polymer dispersion liquid in which a conductive composite having excellent conductivity is dispersed can be more easily obtained.

[0036] The reaction temperature in the reaction solution can be, for example, 20 to 30°C. At the reaction temperature, the polymerization reaction is usually completed in about 4 to 12 hours. The completion of the polymerization reaction can be determined by measuring the amount of unreacted monomer in the reaction solution using gas chromatography or the like.

[0037] It is preferable to remove residues of the catalyst and polymerization initiator added to the reaction liquid from the conductive polymer dispersion after the polymerization reaction. Examples of methods for removing unnecessary components include a method of bringing the conductive polymer dispersion into contact with an ion exchange resin to adsorb unnecessary components onto the ion exchange resin, and a method of ultrafiltrating the conductive polymer dispersion to replace the dispersion medium and remove the unnecessary components. Of these, the method using an ion exchange resin is preferred because it is simple. It is preferable to use a cation exchange resin and an anion exchange resin in combination as the ion exchange resin.

[0038] The conductive polymer dispersion thus obtained may be subjected to a dispersion treatment by a conventional method such as a high-pressure homogenizer, or any other additives may be added thereto.

[0039] <Conductive composite> The conductive complex contains a π-conjugated conductive polymer and a polyanion. In water, the π-conjugated conductive polymer is positively charged and the polyanion is negatively charged, so it is thought that the two form the complex mainly through electrostatic interaction. Typically, the conductive complex is formed by polymerizing a monomer of the π-conjugated conductive polymer in water containing the polyanion, and then naturally doping the polyanion into the formed π-conjugated conductive polymer.

[0040] In the polyanion constituting the conductive composite, only a portion of the anionic groups is doped into the π-conjugated conductive polymer, and there are excess anionic groups that are not involved in the doping. Because the excess anionic groups are hydrophilic groups, the conductive composite has water dispersibility. When the number of all anionic groups in the polyanion is taken as 100 mol %, the excess anionic groups are preferably 30 mol % or more and 90 mol % or less, and more preferably 45 mol % or more and 75 mol % or less.

[0041] (π-conjugated conductive polymer) The π-conjugated conductive polymer may be an organic polymer whose main chain is composed of a π-conjugated system, and examples thereof 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.

[0042] 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-iodothiophene). thiophene), 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-dodecyloxythiophene) oxythiophene), 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 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 because of its excellent conductivity, transparency, and heat resistance. The conductive composite may contain one type of π-conjugated conductive polymer, or two or more types of polymers.

[0043] (polyanion) A polyanion is a polymer having two or more monomer units with an anionic group in the molecule. The anionic group of this polyanion functions as a dopant for a π-conjugated conductive polymer, improving the conductivity of the π-conjugated conductive polymer. The anionic group of the polyanion is preferably a sulfo group or a carboxy group. Specific examples of such polyanions include polymers having sulfo groups, such as 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, polymethacryloyloxybenzenesulfonic acid), poly(2-acrylamido-2-methylpropanesulfonic acid), and polyisoprene sulfonic acid; and polymers having carboxy 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. The polyanion may be a homopolymer formed by polymerizing a single monomer, or a copolymer formed by polymerizing two or more types of monomers. Among these polyanions, polymers having sulfo groups are preferred, and polystyrene sulfonic acid is more preferred, since they can further increase the conductivity.

[0044] The content of the polyanion in the conductive composite is, for example, preferably in the range of 1 part by mass to 1,000 parts by mass, more preferably 10 parts by mass to 700 parts by mass, and even more preferably 100 parts by mass to 500 parts by mass, relative to 100 parts by mass of the π-conjugated conductive polymer. If the content of the polyanion is equal to or greater than the lower limit, the doping effect on the π-conjugated conductive polymer tends to be stronger, resulting in higher conductivity. On the other hand, if the content of the polyanion is equal to or less than the upper limit, the content of the π-conjugated conductive polymer is sufficient, thereby ensuring sufficient conductivity.

[0045] <Conductive polymer dispersion> The conductive polymer dispersion produced in the first embodiment is a conductive polymer dispersion containing a conductive complex and water.

[0046] The content of the polyanion contained in the conductive polymer dispersion is, for example, preferably in the range of 1 part by mass to 1,000 parts by mass, more preferably 10 parts by mass to 700 parts by mass, and even more preferably 100 parts by mass to 500 parts by mass, relative to 100 parts by mass of the π-conjugated conductive polymer. If the content of the polyanion is equal to or greater than the lower limit, the doping effect on the π-conjugated conductive polymer tends to be stronger, resulting in higher conductivity. On the other hand, if the content of the polyanion is equal to or less than the upper limit, a sufficient amount of the π-conjugated conductive polymer can be contained, thereby ensuring sufficient conductivity.

[0047] The total content of the π-conjugated conductive polymer and polyanion relative to the total mass of the conductive polymer dispersion is preferably 0.1% by mass or more and 5.0% by mass or less, and more preferably 0.5% by mass or more and 2.5% by mass or less. When the content is within this preferred range, the dispersibility of the conductive complex is improved. Furthermore, the conductivity of the conductive layer formed from the conductive polymer dispersion can be further improved.

[0048] (dispersion medium) The dispersion medium contained in the conductive polymer dispersion is preferably an aqueous dispersion medium containing water because the conductive composite is hydrophilic. Alternatively, the conductive polymer dispersion may contain a dispersion medium other than water. The dispersion medium other than water is not particularly limited as long as it does not significantly impair the dispersibility of the conductive composite. Since the conductive composite has excess anionic groups derived from the polyanion and has high dispersibility in water, the dispersion medium other than water is preferably a water-soluble organic solvent. Here, the water-soluble organic solvent is an organic solvent that dissolves in an amount of 1 g or more in 100 g of water at 20°C, and examples thereof include alcohol-based solvents, ketone-based solvents, and ester-based solvents. The water-soluble organic solvent contained as the dispersion medium may be one type or two or more types.

[0049] Examples of alcohol-based solvents include methanol, ethanol, 1-propanol, 2-propanol (isopropanol), 2-methyl-2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, allyl alcohol, ethylene glycol, propylene glycol, propylene glycol monomethyl ether, and ethylene glycol monomethyl ether. Examples of the ether solvent include diethyl ether, dimethyl ether, propylene glycol dialkyl ether, and diethylene glycol diethyl ether. 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 nitrogen atom-containing solvents include N-methylpyrrolidone, dimethylacetamide, and dimethylformamide. The water-soluble organic solvent may be contained alone or in combination of two or more kinds. As the water-soluble organic solvent, an alcohol-based solvent or a ketone-based solvent is preferred, and an alcohol-based solvent is more preferred, since this improves the wettability of the conductive polymer dispersion liquid with respect to the substrate.

[0050] The water content relative to the total mass of the dispersion medium excluding the solid content (non-volatile components) of the conductive polymer dispersion is preferably 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, and may be 100 mass%. When water is contained in an amount equal to or greater than the above lower limit, the dispersibility of the conductive composite contained in the conductive polymer dispersion is improved.

[0051] The content of the water-soluble organic solvent relative to the total mass of the aqueous dispersion medium is preferably 70 mass % or less, more preferably 60 mass % or less. Within this preferred range, the wettability of the conductive composite to the substrate can be improved while suppressing deterioration over time in the dispersion stability of the conductive composite in the conductive polymer dispersion.

[0052] The content of the conductive complex relative to the total mass of the conductive polymer dispersion (i.e., the total content of the π-conjugated conductive polymer and the polyanion) is preferably 0.01% by mass or more and 5.0% by mass or less, more preferably 1.0% by mass or more and 4.0% by mass or less, and even more preferably 1.5% by mass or more and 3.0% by mass or less. When the content is at least as large as the lower limit of the above range, the conductivity of the conductive layer formed by curing the conductive polymer dispersion can be further improved. When the content is equal to or less than the upper limit of the above range, the dispersibility of the conductive composite in the conductive polymer dispersion can be improved.

[0053] The viscosity at 23°C of a conductive polymer dispersion prepared by dispersing a conductive complex in water alone at a content of 1.8 mass % is preferably 40 mPa s or less, more preferably 35 mPa s or less, and even more preferably 30 mPa s or less. The viscosity is measured using a tuning fork vibration viscometer in accordance with JIS Z8803:2011 (viscosity measurement method using a vibration viscometer).

[0054] (Polyol compound) The conductive polymer dispersion may contain one or more polyol compounds. Here, the polyol compound refers to a compound having two or more hydroxy groups, which is different from the π-conjugated conductive polymer and the polyanion. By including the polyol compound, the conductivity of the conductive layer, which is a cured product of the conductive polymer dispersion, can be further increased.

[0055] Examples of the polyol compound include one or more selected from ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, glycerin, pentaerythritol, trimethylolpropane, and trimethylolethane.

[0056] The content of the polyol compound in the conductive polymer dispersion is, for example, preferably 100 parts by mass or more and 10,000 parts by mass or less, and more preferably 200 parts by mass or more and 1,000 parts by mass or less, relative to 100 parts by mass of the total of the π-conjugated conductive polymer and polyanion. Within this preferred range, the coatability of the conductive polymer dispersion is improved, and the conductivity of the conductive layer can be further increased.

[0057] The content of the polyol compound relative to the total mass of the conductive polymer dispersion is preferably from 1 to 15% by mass, more preferably from 1 to 10% by mass, and even more preferably from 1 to 5% by mass. Within the above preferred range, the coatability of the conductive polymer dispersion is improved, and the conductivity of the conductive layer can be further increased.

[0058] (Optional additives) The conductive polymer dispersion of this embodiment may contain any additive other than the conductive composite within the scope of the present invention, and the content ratio thereof is determined appropriately depending on the type of additive, but can be, for example, 1 to 1,000 parts by mass per 100 parts by mass of the total of the π-conjugated conductive polymer and polyanion. Here, the optional additive is a compound other than the polyol compound and the dispersion medium.

[0059] Examples of optional additives include surfactants, inorganic conductive agents, antifoaming agents, coupling agents, antioxidants, and ultraviolet absorbers. The surfactant may be a nonionic, anionic, or cationic surfactant, with nonionic surfactants being preferred from the standpoint of storage stability. Polymer surfactants such as polyvinyl alcohol and polyvinylpyrrolidone may also be added. Examples of inorganic conductive agents include metal ions, conductive carbon, etc. Metal ions can be generated by dissolving a metal salt in water. Examples of the antifoaming agent include silicone resin, polydimethylsiloxane, and silicone oil. Examples of the coupling agent include silane coupling agents having a vinyl group, an amino group, an epoxy group, or the like. Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and sugars. Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, oxanilide-based ultraviolet absorbers, hindered amine-based ultraviolet absorbers, and benzoate-based ultraviolet absorbers.

[0060] <Method for manufacturing conductive laminate> A second aspect of the present invention is a method for producing a conductive laminate, comprising the steps of obtaining a conductive polymer dispersion by the production method of the first aspect, and applying the conductive polymer dispersion to at least a partial surface of a substrate and drying the applied conductive polymer dispersion to form a conductive layer.

[0061] Examples of a method for coating (applying) the conductive polymer dispersion onto any surface of a substrate include a method using a coater such as a gravure coater, roll coater, curtain flow coater, spin coater, bar coater, reverse coater, kiss coater, fountain coater, rod coater, air doctor coater, knife coater, blade coater, cast coater, or screen coater; a method using a sprayer such as an air spray, airless spray, or rotor dampening; and an immersion method such as dipping.

[0062] The amount of the conductive polymer dispersion applied to the substrate is not particularly limited, but for example, it is 0.01 to 10.0 g / m as a non-volatile component. 2 The range is preferred.

[0063] The conductive layer can be formed by drying the coating film made of the conductive polymer dispersion applied onto the substrate to remove at least a portion of the dispersion medium and then curing the coating film. Methods for drying the coating film include heat drying, vacuum drying, etc. Heat drying can be performed using, for example, hot air heating or infrared heating. When heat drying is applied, the heating temperature is appropriately set depending on the dispersion medium used, but is usually within the range of 50°C to 200°C. Here, the heating temperature is the temperature set in the drying device. A suitable drying time within the above heating temperature range is preferably 0.5 minutes to 30 minutes, more preferably 1 minute to 15 minutes.

[0064] <Conductive laminate> The conductive laminate produced by the production method of the second aspect comprises a substrate and a conductive layer formed on at least a portion of the surface of the substrate, and the conductive layer contains a cured product of the conductive polymer dispersion.

[0065] [Conductive layer] The conductive layer may be formed over the entire surface of the substrate or over only a portion of the surface. In a conductive film, it is preferable that a conductive layer of substantially uniform thickness is formed over substantially the entire surface of one or the other of the film substrate. When a conductive layer is formed over only a portion of the surface of the substrate, the conductive layer may be, for example, a fine conductive pattern such as a circuit or electrode, or may be simply a roughly divided area where a conductive layer is provided and an area where a conductive layer is not provided exist on the same surface.

[0066] The average thickness of the conductive layer is, for example, preferably 10 nm or more and 100 μm or less, more preferably 20 nm or more and 50 μm or less, and even more preferably 30 nm or more and 30 μm or less. When the average thickness of the conductive layer is equal to or greater than the lower limit, high conductivity can be exhibited, and when the average thickness is equal to or less than the upper limit, the adhesiveness of the conductive layer to the substrate is further improved.

[0067] [Base material] The substrate may be made of an insulating material or a conductive material. The shape of the substrate is not particularly limited, and examples thereof include a shape mainly having a flat surface, such as a film or a substrate. Examples of insulating materials include glass, synthetic resin, and ceramics. Examples of conductive materials include metals, conductive metal oxides, and carbon.

[0068] (Film substrate) When a film substrate is used as the substrate, the conductive laminate becomes a conductive film. Examples of the film substrate include plastic films made of synthetic resins, such as ethylene-methyl methacrylate copolymer resin, ethylene-vinyl acetate copolymer resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacrylate, polycarbonate, polyvinylidene fluoride, polyarylate, styrene-based elastomers, polyester-based elastomers, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyimide, cellulose triacetate, and cellulose acetate propionate. From the viewpoint of improving the adhesion between the film substrate and the conductive layer, the synthetic resin for the film substrate is preferably a polyester resin, and among these, polyethylene terephthalate is preferred.

[0069] The synthetic resin for the film substrate may be amorphous or crystalline. The film substrate may be unstretched or stretched. The film substrate may be subjected to a surface treatment such as corona discharge treatment, plasma treatment, or flame treatment in order to further improve the adhesion of the conductive layer.

[0070] The average thickness of the film substrate is preferably 5 μm or more and 500 μm or less, and more preferably 20 μm or more and 200 μm or less. When the average thickness of the film substrate is equal to or more than the lower limit, the film is less likely to break, and when the average thickness is equal to or less than the upper limit, the film can have sufficient flexibility. The average thickness of the film substrate is determined by measuring the thickness at 10 randomly selected locations and averaging the measured values.

[0071] (glass substrate) Examples of the glass substrate include an alkali-free glass substrate, a soda-lime glass substrate, a borosilicate glass substrate, and a quartz glass substrate. If the substrate contains an alkali component, the conductivity of the conductive layer tends to decrease. Therefore, among the glass substrates, an alkali-free glass is preferred. Here, alkali-free glass refers to a glass composition having an alkali component content of 0.1% by mass or less relative to the total mass of the glass composition.

[0072] The average thickness of the glass substrate is preferably 100 μm or more and 3000 μm or less, and more preferably 100 μm or more and 1000 μm or less. When the average thickness of the glass substrate is equal to or more than the lower limit, the glass substrate is less likely to break, and when the average thickness is equal to or less than the upper limit, the conductive laminate can be made thinner. The average thickness of the glass substrate is determined by measuring the thickness at 10 randomly selected locations and averaging the measured values.

[0073] <Capacitor manufacturing method> A third aspect of the present invention is a method for producing a capacitor, comprising the steps of obtaining a conductive polymer dispersion by the production method of the first aspect, and applying the conductive polymer dispersion to a surface of a dielectric layer formed on the surface of an anode made of a porous valve metal, and drying the applied conductive polymer dispersion to form a solid electrolyte layer.

[0074] The method for manufacturing a capacitor of 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 forming step), arranging a cathode in a position opposite to the dielectric layer (cathode forming step), and forming a solid electrolyte layer on at least a part of the surface of the dielectric layer (film forming step). Each step will be described below with reference to FIG.

[0075] [Dielectric formation process] In this step, the surface of anode 11 made of a porous valve metal is oxidized to form dielectric layer 12. The method for forming dielectric layer 12 is not particularly limited, and examples thereof include a method of anodizing the surface of anode 11 in a chemical conversion treatment electrolyte such as an aqueous solution of ammonium adipate, an aqueous solution of ammonium borate, or an aqueous solution of ammonium phosphate.

[0076] [Cathode formation process] In this step, the cathode 13 is disposed at a position facing the dielectric layer 12. The method for disposing the cathode 13 is not particularly limited, and examples thereof include a method of forming the cathode 13 using a conductive paste such as a carbon paste or a silver paste, and a method of disposing a metal foil such as an aluminum foil facing the dielectric layer 12.

[0077] [Film forming process] In this step, the conductive polymer dispersion liquid is applied to at least a portion of the surface of the dielectric layer 12 and then dried to form the solid electrolyte layer 14.

[0078] Examples of methods that can be used to apply the conductive polymer dispersion include immersion (dip coating), comma coating, reverse coating, lip coating, and microgravure coating. Of these, a method in which the anode 11 is immersed in the conductive polymer dispersion under reduced pressure is preferred. The immersion method allows the conductive polymer dispersion to be applied thoroughly, even to the interior of the porous structure on the surface of the dielectric layer 12. After immersion, the anode is removed and then subjected to the next drying process.

[0079] Drying methods include, for example, room temperature drying, hot air drying, far infrared drying, etc. Among these, hot air drying is preferred. The drying temperature is, for example, preferably 100 to 180° C., more preferably 120 to 150° C. The drying time is, for example, preferably 0.2 to 1 hour. After the drying process, the capacitor can be assembled in the usual manner.

[0080] <Capacitor> The capacitor manufactured in the third embodiment comprises an anode made of a porous body of a valve metal, a dielectric layer made of an oxide of the valve metal, a cathode made of a conductive material provided on the dielectric layer opposite the anode, and a solid electrolyte layer formed between the dielectric layer and the cathode, wherein the solid electrolyte layer contains a cured product of the conductive polymer dispersion.

[0081] An example of an embodiment of the capacitor will be described with reference to Fig. 1. Capacitor 10 shown in Fig. 1 includes an anode 11 made of a porous valve metal, a dielectric layer 12 made of an oxide of the valve metal, a solid electrolyte layer 14 formed on the surface of dielectric layer 12, and a cathode 13 provided on the outermost side. Cathode 13 is provided on the opposite side of anode 11, with dielectric layer 12 and solid electrolyte layer 14 sandwiched therebetween.

[0082] Examples of valve metals that can be used to form the anode 11 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Of these, aluminum, tantalum, and niobium are preferred. Specific examples of the anode 11 include an aluminum foil that has been etched to increase its surface area and then oxidized, and a tantalum or niobium particle sintered body whose surface has been oxidized and then pelletized. Such a processed body becomes a porous body with irregularities formed on the surface.

[0083] The dielectric layer 12 in this embodiment is a layer formed by oxidizing the surface of the anode 11, for example, by anodizing the surface of the metallic anode 11 in an electrolyte such as an aqueous solution of ammonium adipate. Similar to the anode 11, the dielectric layer 12 also has projections and recesses.

[0084] The cathode 13 in this embodiment may be a conductive layer formed from a conductive paste or a metal layer made of a conductive material such as aluminum foil.

[0085] The solid electrolyte layer 14 in this embodiment is formed on the surface of the dielectric layer 12. The solid electrolyte layer 14 covers at least a portion of the surface of the dielectric layer 12, and may cover the entire surface of the dielectric layer 12. The thickness of the solid electrolyte layer 14 may or may not be constant, and may be, for example, 1 μm or more and 100 μm or less.

[0086] [Electrolyte] The capacitor may have an electrolyte solution impregnating the solid electrolyte layer. Examples of the solvent that constitutes the electrolytic solution include alcohol-based solvents such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, and glycerin; lactone-based solvents such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; sulfur-based solvents such as sulfolane, dimethyl sulfoxide, and dimethyl sulfone; amide-based solvents such as N-methylformamide, N,N-dimethylformamide, N-methylacetamide, and N-methylpyrrolidinone; nitrile-based solvents such as acetonitrile and 3-methoxypropionitrile; and water. Examples of the electrolyte constituting the electrolytic solution include organic acids such as adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, maleic acid, toluic acid, enanthic acid, malonic acid, formic acid, decanedicarboxylic acids such as 1,6-decanedicarboxylic acid and 5,6-decanedicarboxylic acid, octanedicarboxylic acids such as 1,7-octanedicarboxylic acid, azelaic acid, and sebacic acid; or boric acid, polyhydric alcohol complex compounds of boric acid obtained from boric acid and polyhydric alcohols; inorganic acids such as phosphoric acid, carbonic acid, and silicic acid; and primary amines (methylamine, ethylamine, propylamine, butylamine, ethylenediamine, etc.), secondary amines (dimethylamine, diethylamine, dipropylamine, methylethylamine, diphenylamine, etc.), tertiary amines (trimethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo(5,4,0)-undecene-7, etc.), tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, etc.), etc. as a cationic component;

[0087] The capacitor is not limited to the above configuration, and a separator may be provided between the dielectric layer and the cathode. An example of a capacitor having a separator provided between the dielectric layer and the cathode is a wound capacitor. Examples of the separator include sheets (including nonwoven fabrics) made of cellulose, polyvinyl alcohol, polyester, polyethylene, polystyrene, polypropylene, polyimide, polyamide, polyvinylidene fluoride, etc., and nonwoven fabrics of glass fibers. The density of the separator is, for example, 0.1 g / cm 3 More than 1.0g / cm 3 The following are included: When a separator is provided, a method of forming a cathode by impregnating the separator with carbon paste or silver paste can also be applied. [Example]

[0088] <Production of Polyanions> [Production Example 1: PSS, Mw 110,000, Na ion content 0.687 mass%] 110 g of sodium styrene sulfonate was dissolved in 820 ml of ion-exchanged water, and while stirring at 80 °C, 8.54 g of sodium peroxodisulfate, previously dissolved in 55 ml of water, was added dropwise over 2 hours, and the solution was stirred for 4 hours. 165 g of cation exchange resin was added to the resulting sodium polystyrene sulfonate-containing solution to remove sodium ions. Then, 80 g of anion exchange resin was added to remove sulfuric acid. The solids content (non-volatile content) of the resulting polystyrene sulfonate (PSS) aqueous solution 1 was 9.0 mass%. The weight-average molecular weight of PSS aqueous solution 1 was measured using an HPLC (high-performance liquid chromatography) system equipped with a GPC (gel permeation chromatography) column and a refractive index detector, with pullulan manufactured by Showa Denko K.K. as a standard substance. Analysis of the GPC chart, in which the vertical axis represents the refractive index signal intensity and the horizontal axis represents retention time, revealed that the first polystyrene sulfonic acid peak showed a weight-average molecular weight (Mw) of 110,000. Furthermore, the amount of sodium ions contained in the PSS aqueous solution 1 was calculated using ICP-OES and found to be 0.687% by mass. Therefore, the amount of sodium ions was 8.26 parts by mass per 100 parts by mass of PSS solid content.

[0089] [Production Example 2: PSS, Mw 110,000, Na ion content 0.445 mass%] The same procedure as in Production Example 1 was repeated, except that 297 g of cation exchange resin was added to the sodium polystyrene sulfonate-containing solution obtained in the same manner as in Production Example 1. The solids content of the resulting polystyrene sulfonic acid (PSS) aqueous solution 2 was 8.7 mass %. Its weight-average molecular weight was 110,000, and the sodium ion content was 0.445 mass %. The sodium ion content was 5.39 mass parts per 100 mass parts of the PSS solid content.

[0090] [Production Example 3: PSS, Mw 110,000, Na ion content 0.428 mass%] The same procedure as in Production Example 1 was repeated, except that 330 g of a cation exchange resin was added to the sodium polystyrene sulfonate-containing solution obtained in the same manner as in Production Example 1. The solids content of the resulting polystyrene sulfonic acid (PSS) aqueous solution 3 was 8.7 mass %. Its weight-average molecular weight was 110,000, and the sodium ion content was 0.428 mass %. The sodium ion content was 5.17 mass parts per 100 mass parts of the PSS solid content.

[0091] [Production Example 4: PSS, Mw 110,000, Na ion content 0.396 mass%] The same procedure as in Production Example 1 was repeated, except that 363 g of a cation exchange resin was added to the sodium polystyrene sulfonate-containing solution obtained in the same manner as in Production Example 1. The solids content of the resulting polystyrene sulfonic acid (PSS) aqueous solution 4 was 8.7 mass %. Its weight-average molecular weight was 110,000, and the sodium ion content was 0.396 mass %. The sodium ion content was 4.77 mass parts per 100 mass parts of the PSS solid content.

[0092] [Production Example 5: PSS, Mw 110,000, Na ion content 0.307 mass%] The same procedure as in Production Example 1 was repeated, except that 495 g of a cation exchange resin was added to the sodium polystyrene sulfonate-containing solution obtained in the same manner as in Production Example 1. The solids content of the resulting polystyrene sulfonic acid (PSS) aqueous solution 5 was 8.5 mass %. Its weight-average molecular weight was 110,000, and the sodium ion content was 0.307 mass %. The sodium ion content was 3.75 mass parts per 100 mass parts of the PSS solid content.

[0093] [Production Example 6: PSS, Mw 110,000, Na ion content 1.242 mass%] The same procedure as in Production Example 1 was repeated, except that no cation exchange resin was added to the sodium polystyrene sulfonate-containing solution obtained in the same manner as in Production Example 1. The solids content of the resulting polystyrene sulfonic acid (PSS) aqueous solution 6 was 10.5 mass %. Its weight-average molecular weight was 110,000, and the sodium ion content was 1.242 mass %. The sodium ion content was 13.42 mass parts per 100 mass parts of the PSS solid content.

[0094] [Production Example 7: PSS, Mw 100,000, ammonium ion content 0.16 mass%] 55 g of ammonium styrene sulfonate was dissolved in 880 ml of ion-exchanged water, and while stirring at 80 °C, 2.80 g of ammonium peroxodisulfate, previously dissolved in 55 ml of water, was added dropwise over 2 hours, and the solution was stirred for 4 hours. 165 g of cation exchange resin was added to the resulting ammonium polystyrene sulfonate-containing solution to remove ammonium ions. Then, 80 g of anion exchange resin was added to remove sulfuric acid. The solids content (non-volatile content) of the resulting polystyrene sulfonic acid (PSS) aqueous solution 7 was 5.1 mass%. The weight-average molecular weight of PSS aqueous solution 7 was measured using a HPLC (high-performance liquid chromatography) system equipped with a GPC (gel permeation chromatography) column and a refractive index detector, with pullulan manufactured by Showa Denko K.K. as a standard substance. Analysis of the GPC chart, in which the vertical axis represents the refractive index signal intensity and the horizontal axis represents retention time, revealed that the first polystyrene sulfonic acid peak showed a weight-average molecular weight (Mw) of 100,000. Furthermore, the amount of ammonium ions contained in the PSS aqueous solution 7 was calculated using ion chromatography and found to be 0.16% by mass. Therefore, the amount of ammonium ions was 3.24 parts by mass per 100 parts by mass of PSS solid content.

[0095] [Production Example 8: PSS, Mw 100,000, ammonium ion content 0.52 mass%] The same procedure as in Production Example 7 was repeated, except that no cation exchange resin was added to the ammonium polystyrene sulfonate-containing solution obtained in the same manner as in Production Example 7. The solids content of the resulting polystyrene sulfonic acid (PSS) aqueous solution 8 was 5.6 mass %. Its weight-average molecular weight was 100,000, and the amount of ammonium ions was 0.52 mass %. The amount of ammonium ions was 10.24 mass parts per 100 mass parts of PSS solids.

[0096] [Table 1]

[0097] Example 1 6.86 g of 3,4-ethylenedioxythiophene, 180 g of the polystyrene sulfonic acid aqueous solution (PSS aqueous solution 1) obtained in Production Example 1, and 721.92 g of ion-exchanged water were mixed at 26°C. The resulting mixture was maintained at 26°C and stirred while adding an oxidation catalyst solution of 1.38 g of ferric sulfate dissolved in 21.64 g of ion-exchanged water, and stirring was continued for 30 minutes. The monovalent cation concentration, i.e., sodium ion concentration, of the mixture immediately before adding the polymerization initiator was 0.133% by mass. The monovalent cation content was 8.26 parts by mass per 100 parts by mass of polyanion (the same ratio as PSS aqueous solution 1). Next, 7.50g of sodium peroxodisulfate dissolved in 60.70g of ion-exchanged water was gradually added dropwise over 2 hours, and the mixture was stirred for another 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 resulted in a blue PEDOT-PSS aqueous dispersion with a PEDOT:PSS ratio of 1:2.4 (by mass). The solids (non-volatile components) of the resulting dispersion were 1.8% by mass.

[0098] <Example 2> A PEDOT-PSS aqueous dispersion with a solids concentration of 1.8% by mass was obtained in the same manner as in Example 1, except that the PSS aqueous solution 2 obtained in Production Example 2 was used, its amount was changed to 186.21 g, the amount of ion-exchanged water was changed to 715.71 g, and the sodium ion concentration of the mixed solution immediately before adding the polymerization initiator was changed to 0.089% by mass.

[0099] Example 3 A PEDOT-PSS aqueous dispersion with a solid content of 1.8% by mass was obtained in the same manner as in Example 1, except that the PSS aqueous solution 3 obtained in Production Example 3 was used, its amount was changed to 186.21 g, the amount of ion-exchanged water was changed to 715.71 g, and the sodium ion concentration of the mixed solution immediately before adding the oxidizing agent was changed to 0.086% by mass.

[0100] Example 4 A PEDOT-PSS aqueous dispersion with a solid content of 1.8% by mass was obtained in the same manner as in Example 1, except that the PSS aqueous solution 4 obtained in Production Example 4 was used, its amount was changed to 186.21 g, the amount of ion-exchanged water was changed to 715.71 g, and the sodium ion concentration of the mixed solution immediately before adding the oxidizing agent was changed to 0.079% by mass.

[0101] <Example 5> A PEDOT-PSS aqueous dispersion with a solid content of 1.8% by mass was obtained in the same manner as in Example 1, except that the PSS aqueous solution 5 obtained in Production Example 5 was used, the amount of PSS aqueous solution was changed to 190.59 g, the amount of ion-exchanged water was changed to 711.33 g, and the sodium ion concentration of the mixed solution immediately before adding the oxidizing agent was changed to 0.063% by mass.

[0102] <Comparative Example 1> The same procedure as in Example 1 was carried out using the PSS aqueous solution 6 obtained in Production Example 6, except that the amount of PSS aqueous solution 6 was changed to 154.29 g, the amount of ion-exchanged water was changed to 747.63 g, and the sodium ion concentration of the mixed solution immediately before adding the oxidizing agent was changed to 0.206 mass %, to obtain a PEDOT-PSS aqueous dispersion with a solid concentration of 1.8 mass %.

[0103] Example 6 A PEDOT-PSS aqueous dispersion with a solids concentration of 1.8% by mass was obtained in the same manner as in Example 1, except that the PSS aqueous solution 7 obtained in Production Example 7 was used, its amount was changed to 317.65 g, the amount of ion-exchanged water was changed to 584 g, the ammonium concentration of the mixed solution immediately before the addition of the oxidizing agent was changed to 0.055% by mass, and then 7.19 g of ammonium peroxodisulfate was dissolved in 60.70 g of ion-exchanged water.

[0104] <Comparative Example 2> A PEDOT-PSS aqueous dispersion with a solids concentration of 1.8% by mass was obtained in the same manner as in Example 1, except that the PSS aqueous solution 8 obtained in Production Example 8 was used, its amount was changed to 289.29 g, the amount of ion-exchanged water was changed to 613 g, the ammonium concentration of the mixed solution immediately before adding the oxidizing agent was changed to 0.055% by mass, and then 7.19 g of ammonium peroxodisulfate was dissolved in 60.70 g of ion-exchanged water.

[0105] <Viscosity evaluation> The viscosity of the PEDOT-PSS aqueous dispersion (solid content concentration: 1.8% by mass) obtained in each example was measured at 23° C. using a vibration viscometer. The measurement results are shown in Table 2. The viscosity values ​​mentioned above are values ​​measured at 23°C using a tuning fork vibration viscometer in accordance with JIS Z8803:2011 (viscosity measurement method using a vibration viscometer).

[0106] <Evaluation of conductivity> To 5.0 g of the conductive polymer dispersion (PEDOT-PSS aqueous dispersion) obtained in each example, 5.0 g of methanol and 0.25 g of dimethyl sulfoxide were added and thoroughly mixed to prepare a coating material. This coating material was applied to a polyethylene terephthalate film (Lumirror T60, manufactured by Toray Industries, Inc.) using a No. 08 bar coater and then heated and dried at 100°C for 1 minute to obtain a conductive film. The surface resistance of the resulting conductive film was measured using a resistivity meter (Loresta, manufactured by Nitto Seiko Analytech Co., Ltd.) at an applied voltage of 10 V. The results are shown in Table 2. The lower the surface resistance value, the higher and better the conductivity.

[0107] [Table 2]

[0108] From the above, it is clear that Examples 1 to 6 according to the present invention have a sufficiently low viscosity and can form a conductive layer that exhibits superior conductivity compared to Comparative Examples 1 and 2.

Claims

1. A method for producing a conductive polymer dispersion, comprising: adding a polymerization initiator for polymerizing a monomer to a reaction liquid containing a polyanion, a monomer that forms a π-conjugated conductive polymer, an aqueous dispersion medium, and a catalyst containing a transition metal to initiate a polymerization reaction, thereby forming a conductive composite containing the π-conjugated conductive polymer and the polyanion, the amount of monovalent cations capable of forming a salt with an anion group of the polyanion contained in the reaction solution immediately before the addition of the polymerization initiator is 10.0 parts by mass or less relative to 100 parts by mass of the polyanion.

2. 2. The method for producing a conductive polymer dispersion according to claim 1, wherein an aqueous polyanion solution containing the polyanion to be added to the reaction liquid is prepared in advance, and the aqueous polyanion solution is added to the reaction liquid after removing the monovalent cations contained in the aqueous polyanion solution.

3. a preliminary step of polymerizing a monomer that forms the polyanion in the presence of water to obtain the aqueous polyanion solution, The method for producing a conductive polymer dispersion according to claim 2 , wherein an alkali metal salt or an ammonium salt of styrenesulfonic acid is used as the monomer in the preliminary step.

4. 4. The method for producing a conductive polymer dispersion according to claim 3, wherein the content of alkali metal ions and ammonium relative to the total mass of the aqueous polyanion solution obtained in the preliminary step is 1.0 mass% or less after the treatment for removing the monovalent cations.

5. The method for producing a conductive polymer dispersion according to claim 2 , wherein the monovalent cations contained in the aqueous polyanion solution are removed using an ion exchange resin.

6. 2. The method for producing a conductive polymer dispersion according to claim 1, wherein an amount of the monovalent cation contained in the reaction liquid immediately before adding the polymerization initiator is 0.150 mass % or less with respect to the total mass of the reaction liquid.

7. 2. The method for producing a conductive polymer dispersion according to claim 1, wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene).

8. The method for producing a conductive polymer dispersion according to claim 7 , wherein the polyanion is polystyrene sulfonic acid.

9. 9. A method for producing a conductive laminate, comprising: obtaining a conductive polymer dispersion by the production method according to any one of claims 1 to 8; and applying the conductive polymer dispersion to at least a part of a surface of a substrate and drying the applied conductive polymer dispersion to form a conductive layer.

10. A step of obtaining a conductive polymer dispersion by the production method according to any one of claims 1 to 8; and applying the conductive polymer dispersion to a surface of a dielectric layer formed on the surface of an anode made of a porous valve metal body, and drying the conductive polymer dispersion to form a solid electrolyte layer.

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