Method for producing conductive polymer dispersion and method for producing conductive laminate

Abstract

To provide a method for producing a conductive polymer dispersion capable of forming a conductive layer having good transparency and excellent conductivity, a method for producing a conductive laminate using the same, and a method for producing a capacitor.SOLUTION: A method for producing a conductive polymer dispersion, including a step of polymerizing a monomer in a reaction liquid obtained by blending a polyanion aqueous solution containing a polyanion and water, the monomer for forming a π - conjugated conductive polymer, and other optional components to form a conductive composite containing the π - conjugated conductive polymer and the polyanion, thereby obtaining a conductive polymer dispersion in which the conductive composite is dispersed in an aqueous dispersion medium, wherein a sodium ion concentration and a sulfate ion concentration in the polyanion aqueous solution satisfy specific conditions.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. When a coating material made from a conductive polymer dispersion containing a conductive complex is applied to a transparent substrate such as a transparent film and dried, a conductive laminate such as a conductive film having a transparent conductive layer formed on the surface is obtained. For example, Patent Document 1 discloses a conductive polymer dispersion blended with polyvinylpyrrolidone to obtain a viscosity suitable for screen printing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-054929 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have investigated ways to bring out the inherent potential of the conductive composite, rather than blending various additives into the conductive polymer dispersion in order to improve the conductivity and transparency of the conductive layer formed using the conductive polymer dispersion, and have completed the present invention.

[0005] The present invention provides a method for producing a conductive polymer dispersion capable of forming a conductive layer having good transparency and excellent conductivity, a method for producing a conductive laminate using the same, and a method for producing a capacitor. [Means for solving the problem]

[0006] [1] A method for producing a conductive polymer dispersion, comprising the steps of: forming a conductive complex containing the π-conjugated conductive polymer and the polyanion by polymerizing the monomer in a reaction liquid obtained by blending an aqueous polyanion solution containing a polyanion and water, a monomer that forms a π-conjugated conductive polymer, and other optional components; and obtaining a conductive polymer dispersion in which the conductive complex is dispersed in an aqueous dispersion medium, wherein the aqueous polyanion solution satisfies the following condition A: <Condition A> The concentration of sodium ions in the aqueous polyanion solution is 30 ppm or less per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, and the concentration of sulfate ions in the aqueous polyanion solution is 60 ppm or more per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, relative to the total mass of the aqueous polyanion solution.

[0007] [2] The method for producing a conductive polymer dispersion according to [1], wherein the aqueous polyanion solution further satisfies the following condition B: <Condition B> The concentration of sodium ions in the aqueous polyanion solution is 2 ppm or more per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, and the concentration of sulfate ions in the aqueous polyanion solution is 600 ppm or less per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, relative to the total mass of the aqueous polyanion solution.

[0008] [3] The method for producing a conductive polymer dispersion according to [1] or [2], wherein the content of water relative to the total mass of the conductive polymer dispersion is 70 mass % or more. [4] The method for producing a conductive polymer dispersion according to any one of [1] to [3], further comprising a preliminary step of radically polymerizing a monomer that forms the polyanion in the presence of water to obtain the aqueous polyanion solution, wherein in the preliminary step, a persulfate is used to initiate the radical polymerization, and sulfate ions are produced as a by-product. [5] The method for producing a conductive polymer dispersion according to any one of [1] to [4], wherein the sulfate ions contained in the aqueous polyanion solution are removed before the aqueous polyanion solution is mixed with the reaction liquid. [6] The method for producing a conductive polymer dispersion according to any one of [1] to [5], wherein the weight-average molecular weight of the polyanion is 100,000 or more and 1,000,000 or less. [7] The method for producing a conductive polymer dispersion according to any one of [1] to [6], wherein the polyanion is polystyrene sulfonic acid. [8] The method for producing a conductive polymer dispersion according to any one of [1] to [7], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene). [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 the surface of an anode made of a porous valve metal body, and drying the applied conductive polymer dispersion to form a solid electrolyte layer. [Effects of the Invention]

[0009] According to the present invention, a conductive polymer dispersion capable of forming a conductive layer having good transparency and excellent conductivity can be easily produced. The conductive polymer dispersion thus produced is suitable for producing a conductive laminate or a capacitor.

[0010] This invention is believed to contribute to SDG Goal 12, "Responsible Consumption and Production."

[0011] 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]

[0012] [Figure 1] FIG. 1 is a cross-sectional view illustrating one embodiment of a capacitor. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Method for producing conductive polymer dispersion> A first aspect of the present invention is a method for producing a conductive polymer dispersion, comprising the steps of: forming a conductive composite containing the π-conjugated conductive polymer and the polyanion by polymerizing the monomer in a reaction liquid obtained by blending an aqueous polyanion solution containing a polyanion and water, a monomer that forms a π-conjugated conductive polymer, and other optional components; and obtaining a conductive polymer dispersion in which the conductive composite is dispersed in an aqueous dispersion medium.

[0014] As a specific example of this embodiment, the following steps 1 and 2 can be mentioned.

[0015] [Process 1 (preliminary process)] In step 1, an aqueous polyanion solution is prepared. Step 1 is a step in which a polymerization initiator is added 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.

[0016] 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 a cation such as sodium or potassium. The polymerizable anionic monomer used in this step is preferably one or more selected from known monomers capable of forming polyanions, examples of which will be given 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. 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.

[0017] Examples of the polymerization initiator include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. The amount of the polymerization initiator to be added relative to the total mass of the first reaction liquid is, for example, 0.01 to 1.0% by mass. By adjusting the amount and addition rate of the polymerization initiator, the weight-average molecular weight of the polyanion formed by polymerization can be adjusted.

[0018] The completion of the polymerization reaction of the polyanion in step 1 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.

[0019] 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 with a cation exchange resin. The weight-average molecular weight Mw of the polyanion contained in the second reaction solution is preferably 10,000 to 1,000,000, more preferably 50,000 to 800,000.

[0020] The second reaction liquid may contain sodium ions derived from the monomers that form the polyanion and the polymerization initiator. From the viewpoint of reducing sodium ions carried over into the reaction liquid in the subsequent step 2, it is preferable to obtain an aqueous polyanion solution from which sodium ions contained in the second reaction liquid have been removed and use this as the reaction liquid in step 2.

[0021] Examples of methods for purifying the polyanion by removing sodium ions from the second reaction solution include ultrafiltration and cation exchange resin adsorption. In the ultrafiltration method, low molecular weight sodium ions pass through the ultrafiltration membrane, while high molecular weight polyanions do not, so the two can be separated. An example of the cation exchange resin is Duolite C255LFH manufactured by Sumika Chemtex Co., Ltd.

[0022] The second reaction liquid may contain sulfate ions as a by-product of hydrolysis of the polymerization initiator. From the viewpoint of reducing the amount of sulfate ions carried over into the reaction liquid in the subsequent step 2, it is preferable to remove the sulfate ions from the second reaction liquid to obtain an aqueous polyanion solution and use this as the reaction liquid in step 2.

[0023] Examples of methods for purifying the polyanion by removing sulfate ions from the second reaction solution include ultrafiltration and anion exchange resin adsorption. In ultrafiltration, low molecular weight sulfate ions pass through the ultrafiltration membrane, while high molecular weight polyanions do not, so the two can be separated. In the anion exchange resin adsorption method, if an anion exchange resin is used that preferentially binds low molecular weight sulfate ions, low molecular weight substances will be adsorbed while high molecular weight polyanions will hardly be adsorbed, so the two can be separated. An example of such an anion exchange resin is Duolite A368MS manufactured by Sumika Chemtex Co., Ltd.

[0024] The sodium ion concentration in the aqueous polyanion solution or reaction solution can be measured by a known method using inductively coupled plasma mass spectrometry (ICP-MS).

[0025] The sulfate ion concentration in the aqueous polyanion solution or reaction solution can be measured by a known method using ion chromatography. In this case, it is preferable to prepare a calibration curve in advance using standard samples with known sulfate ion concentrations.

[0026] In this embodiment, from the viewpoint of obtaining a conductive polymer dispersion capable of forming a conductive layer having good transparency and excellent conductivity, it is preferable that the aqueous polyanion solution satisfies the following condition A.

[0027] <Condition A> The concentration of sodium ions in the aqueous polyanion solution is 30 ppm or less per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, and the concentration of sulfate ions in the aqueous polyanion solution is 60 ppm or more per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, relative to the total mass of the aqueous polyanion solution.

[0028] In this embodiment, from the viewpoint of obtaining a conductive polymer dispersion capable of forming a conductive layer having good transparency and excellent conductivity, it is preferable that the aqueous polyanion solution further satisfies the following condition B.

[0029] <Condition B> The concentration of sodium ions in the aqueous polyanion solution is 2 ppm or more per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, and the concentration of sulfate ions in the aqueous polyanion solution is 600 ppm or less per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, relative to the total mass of the aqueous polyanion solution.

[0030] [Process 2] Next, in step 2, a conductive composite containing the π-conjugated conductive polymer and the polyanion is formed by polymerizing the monomer in a reaction solution prepared by blending an aqueous polyanion solution containing a polyanion and water, a monomer that forms a π-conjugated conductive polymer, and other optional components.

[0031] Step 2 is preferably a step of adding a monomer that forms a π-conjugated conductive polymer and an arbitrary polymerization initiator to the aqueous polyanion solution obtained in Step 1 to form 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 2 may be the one obtained in step 1, or may be an aqueous solution prepared by dissolving a commercially available polyanion in water, as long as it satisfies the above-mentioned conditions A and B.

[0032] In step 2, the third reaction liquid containing the conductive complex can be obtained by a known method, except for adding an aqueous polyanion solution adjusted to a specific ion concentration.

[0033] The monomer 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, which can form PEDOT having excellent conductivity and heat resistance, is most preferred.

[0034] Examples of optional components that may be added to the reaction liquid include water, a catalyst, and a polymerization initiator.

[0035] Examples of the catalyst include transition metal compounds such as ferric chloride, ferric sulfate, ferric nitrate, and cupric chloride.

[0036] Examples of the polymerization initiator include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate.

[0037] The persulfate added to the reaction solution hydrolyzes and functions as a radical polymerization initiator, while also generating sulfate ions as a by-product. The sulfate ion concentration specified by conditions A and B is the sulfate ion concentration in the aqueous polyanion solution before addition to the reaction solution, and is a factor that can affect the physicochemical state of the polyanion during storage. Although sulfate ions derived from the polymerization initiator added to the reaction solution may affect the polyanion that forms the conductive complex, as shown in the examples below, the effects of the present invention can be fully achieved by adjusting the sulfate ion concentration in the aqueous polyanion solution.

[0038] The sodium ion concentration in the aqueous polyanion solution, like the sulfate ion concentration, is a factor that can affect the physicochemical state of the polyanion during storage. Although sodium ions derived from the polymerization initiator, etc., added to the reaction solution may affect the polyanion that forms the conductive complex, as shown in the examples below, the effects of the present invention can be fully achieved by adjusting the sodium ion concentration in the aqueous polyanion solution.

[0039] The polymerization initiator is preferably added last to the reaction solution in which all other reaction components have been mixed, to initiate polymerization. The polymerization initiator is preferably dissolved in a small amount of water and added to the reaction solution. The polymerization initiator may be added all at once, or may be added stepwise. It is preferable to add a certain amount slowly over a predetermined time (for example, 2 to 4 hours).

[0040] It is preferable to reduce the amount of dissolved oxygen in the reaction solution by blowing an inert gas such as nitrogen gas into the reaction solution before adding the polymerization initiator. The amount of dissolved oxygen in the reaction solution is preferably 0.50 mg / L or less, more preferably 0.30 mg / L or less, and even more preferably 0.15 mg / L or less. By reducing the amount of dissolved oxygen, the polymerization reaction becomes smooth and the amount of polymerization initiator added can be reduced. The amount of dissolved oxygen in the reaction solution can be measured using a known dissolved oxygen meter.

[0041] The amount of the polymerization initiator to be added relative to the total mass of the reaction solution during the polymerization reaction is, for example, 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. Within the above range, the polymerization reaction proceeds sufficiently, and the monomers blended in the reaction liquid can be prevented from remaining unreacted.

[0042] The content of the monomer relative to the total mass of the reaction solution during the polymerization reaction is, for example, preferably 0.01% by mass to 2.0% by mass, more preferably 0.1% by mass to 1.0% by mass, and even more preferably 0.3% by mass to 0.8% by mass. Within the above range, the polymerization reaction proceeds sufficiently, and the monomers blended in the reaction liquid can be prevented from remaining unreacted.

[0043] The content of the polyanion relative to the total mass of the reaction solution during the polymerization reaction is, for example, preferably 0.1% by mass to 3.0% by mass, more preferably 0.5% by mass to 2.0% by mass, and even more preferably 1.0% by mass to 1.5% by mass. Within the above range, the π-conjugated conductive polymer formed in the reaction solution forms a sufficient complex with the polyanion, resulting in good dispersibility in water.

[0044] 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.

[0045] 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 removal methods include a method of bringing the conductive polymer dispersion into contact with an ion exchange resin to adsorb the catalyst and polymerization initiator onto the ion exchange resin, and a method of ultrafiltrating the conductive polymer dispersion to replace the dispersion medium and remove the catalyst and polymerization initiator. Of these, the method using an ion exchange resin is preferred because it is simple. The ion exchange resin is preferably a combination of a cation exchange resin and an anion exchange resin.

[0046] The conductive polymer dispersion obtained as described above can be stirred to form a high-speed turbulent flow by applying high shear force using a high-pressure homogenizer or the like, thereby increasing the dispersibility of the conductive composite in the conductive polymer dispersion.

[0047] If necessary, any additives such as an organic solvent or a polyol compound may be added to the conductive polymer dispersion liquid obtained above.

[0048] <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.

[0049] 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.

[0050] (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.

[0051] 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.

[0052] (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.

[0053] The content of the polyanion in the conductive composite is, for example, preferably in the range of 10 parts by mass to 1,000 parts by mass, more preferably 100 parts by mass to 700 parts by mass, and even more preferably 200 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. Generally, the composition ratio of the π-conjugated conductive polymer and the polyanion that constitute the conductive composite formed in this embodiment reflects the composition ratio of the π-conjugated conductive polymer monomer and the polyanion that are blended in the reaction solution in step 2.

[0054] <Conductive polymer dispersion> The conductive polymer dispersion produced in the first embodiment is a conductive polymer dispersion containing a conductive complex and water.

[0055] 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 mass % or more and 5.0 mass % or less, and more preferably 0.5 mass % or more and 2.5 mass % or less. Within the above preferred range, the dispersibility of the conductive complex is improved, the transparency of the conductive layer formed is improved, and the conductivity is improved.

[0056] (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 dispersion medium 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.

[0057] 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.

[0058] 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 complex contained in the conductive polymer dispersion is improved, the transparency of the formed conductive layer is improved, and the conductivity is improved.

[0059] The content of the water-soluble organic solvent relative to the total mass of the aqueous dispersion medium is preferably 30 to 70 mass %, more preferably 40 to 60 mass %, and the content of water relative to the total mass of the aqueous dispersion medium is preferably 70 to 30 mass %, more preferably 60 to 40 mass %. When the content is within the above preferred range, it is possible to improve the wettability of the conductive composite to the substrate while suppressing deterioration over time in the dispersion stability of the conductive composite in the conductive polymer dispersion.

[0060] The content of the conductive complex relative to the total mass of the conductive polymer dispersion is preferably 0.1 mass % or more and 3.0 mass % or less, more preferably 0.3 mass % or more and 2.0 mass % or less, and even more preferably 0.6 mass % or more and 1.6 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, and transparency can be made better.

[0061] (Optional additives) The conductive polymer dispersion of this embodiment may contain any additive other than the conductive composite within a range that does not impair the spirit of the present invention. The content ratio of the additive is determined appropriately depending on the type of additive, but can be, for example, 1 to 1000 parts by mass per 100 parts by mass of the total of the π-conjugated conductive polymer and polyanion.

[0062] 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.

[0063] <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 coating.

[0064] 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, a roll coater, a curtain flow coater, a spin coater, a bar coater, a reverse coater, a kiss coater, a fountain coater, a rod coater, an air doctor coater, a knife coater, a blade coater, a cast coater, or a screen coater; a method using a sprayer such as an air spray, an airless spray, or a rotor dampening; and an immersion method such as dipping.

[0065] 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.

[0066] 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 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.

[0067] <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.

[0068] [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.

[0069] 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.

[0070] [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.

[0071] (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.

[0072] 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.

[0073] 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.

[0074] (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.

[0075] 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.

[0076] <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.

[0077] 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.

[0078] [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.

[0079] [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.

[0080] [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.

[0081] 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.

[0082] 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.

[0083] <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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] [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;

[0090] 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]

[0091] (Production Example 1) Production of polystyrene sulfonic acid 100 g of sodium styrenesulfonate was dissolved in 800 ml of ion-exchanged water, and while stirring at 80°C, 3 g of an oxidizing agent solution of sodium persulfate previously dissolved in 100 ml of water was added dropwise at a constant rate over 120 minutes. The solution was stirred for a further 2 hours, and then 1.5 g of an oxidizing agent solution of sodium persulfate previously dissolved in 50 ml of water was added dropwise at a constant rate over 60 minutes. The solution was stirred for a further 1 hour and then cooled to 25°C. To the obtained sodium polystyrene sulfonate solution, 300 g of Duolite C255LFH (Sumika Chemtex Corporation, cation exchange resin) was added and stirred for 1 hour. After filtering to remove the ion exchange resin, the liquid was again added with 300 g of Duolite C255LFH (Sumika Chemtex Corporation, cation exchange resin) and 600 g of water and stirred for 1 hour. After filtering to remove the ion exchange resin, an aqueous polystyrene sulfonate solution with a PSS concentration of 5.0 mass% was obtained.

[0092] The weight-average molecular weight (Mw) of the PSS contained in the polystyrene sulfonic acid aqueous solution obtained above was measured by gel permeation chromatography (GPC) using pullulan of known weight-average molecular weight as the standard substance, and was found to be 176,000.

[0093] The weight-average molecular weight was measured using a Nexera high-performance liquid chromatograph manufactured by Shimadzu Corporation, using a 50 mM aqueous NaNO3 solution as the solvent, a Shodex OHpack SB-806M HQ column, and a RID-20A detector. The solvent temperature was set to 40°C, the flow rate was set to 1.0 ml / min, the PSS concentration in the sample was adjusted to 0.1% by mass, and 100 μl of the sample filtered through a membrane filter with a pore size of 0.45 μm was injected, and the measurement was performed using the Lab Solutions analysis software (Shimadzu Corporation).

[0094] The sodium concentration in a 5.0 mass% polystyrene sulfonic acid aqueous solution was measured by inductively coupled plasma mass spectrometry (ICP-MS) using XSTC-331, a known general-purpose mixed standard solution, as the standard substance, and was found to be 50 ppm (10 ppm per 1.0 mass% PSS).

[0095] The sodium concentration was measured using a triple quadrupole ICP-MS Agilent 8900 from Agilent Technologies Inc. A mixture of nitric acid and the sample was heated and decomposed in a microwave oven in a clean room, then diluted with ultrapure water and the amount of sodium was measured under an argon gas atmosphere.

[0096] The sulfate ion concentration in a 5.0 mass% polystyrene sulfonic acid aqueous solution was measured by high-performance liquid chromatography (HPLC) using anion mixed standard solution III, a known general-purpose mixed standard solution, as the standard substance, and was found to be 1400 ppm (280 ppm per 1.0 mass% PSS).

[0097] Sulfate ions were measured using an LC-2000 (manufactured by JASCO Corporation) with a column: Shodex IC SI-90 4E and a detector: an electrical conductivity detector, and the ion concentration was calculated.

[0098] Example 1: Preparation of conductive polymer dispersion 5.0 g of 3,4-ethylenedioxythiophene (EDOT), 300.0 g of the 5% by mass aqueous solution of polystyrene sulfonic acid from Production Example 1, and 536.2 g of ion-exchanged water were mixed, and then nitrogen was blown into the mixture until the dissolved oxygen content reached 0.15 mg / L or less. The dissolved oxygen content was measured using a portable dissolved oxygen meter HI 9146N manufactured by Hannains Solments Japan Co., Ltd. The resulting mixed solution was kept at 10° C., and 50.0 g of a 6% by mass aqueous solution of ferric sulfate was added while stirring. Next, 108.8 g of an 8% by mass aqueous solution of sodium persulfate was added, and the resulting reaction solution was reacted with stirring for 8 hours. By the above reaction, a conductive polymer dispersion containing a conductive complex (PEDOT-PSS) containing poly(3,4-ethylenedioxythiophene), a π-conjugated conductive polymer, and polystyrene sulfonic acid was obtained.

[0099] To this conductive polymer dispersion, 162 g of Duolite C255LFH (a cation exchange resin manufactured by Sumika Chemtex Corporation), 162 g of Duolite A368MS (an anion exchange resin manufactured by Sumika Chemtex Corporation), and 200 g of ion-exchanged water were added, and the mixture was filtered to remove the ion exchange resin, yielding 850 g of a conductive polymer dispersion (PEDOT-PSS dispersion) from which the oxidant and catalyst had been removed and which had a concentration of 1.3 mass% of the conductive complex as a non-volatile component. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0100] Measurement of unpolymerized EDOT was performed using a gas chromatograph GC-2010plus manufactured by Shimadzu Corporation, a capillary column DB-5MS, and a flame ionization detector (FID).The sample was diluted five times with methanol, and 0.4 μl of the sample filtered through a membrane filter with a pore size of 5 μm was injected.The analysis was performed using the Lab Solutions analysis software (Shimadzu Corporation).

[0101] (Production Example 2) Production of polystyrene sulfonic acid A 5.0% by mass aqueous polystyrene sulfonic acid solution containing PSS with a weight-average molecular weight of 107,000 was obtained in the same manner as in Production Example 1, except that the amount of "3 g of sodium persulfate" in Production Example 1 was changed to 9 g. The sodium concentration was 125 ppm (25 ppm per 1.0% by mass of PSS) and the sulfate ion concentration was 3,185 ppm (637 ppm per 1.0% by mass of PSS).

[0102] Example 2: Preparation of conductive polymer dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that the "polystyrene sulfonic acid aqueous solution of Production Example 1" in Example 1 was changed to the "polystyrene sulfonic acid aqueous solution of Production Example 2." The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0103] (Production Example 3) Production of polystyrene sulfonic acid A 5.0% by mass aqueous polystyrene sulfonic acid solution containing PSS with a weight-average molecular weight of 250,000 was obtained in the same manner as in Production Example 1, except that the amount of "3 g of sodium persulfate" in Production Example 1 was changed to 2 g. The sodium concentration was 110 ppm (22 ppm per 1.0% by mass of PSS) and the sulfate ion concentration was 795 ppm (159 ppm per 1.0% by mass of PSS).

[0104] Example 3: Preparation of conductive polymer dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "250 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 586.2 g of ion-exchanged water" in Production Example 3. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0105] (Production Example 4) Production of polystyrene sulfonic acid To 900 g of the 5.0 mass% polystyrene sulfonic acid aqueous solution obtained in Production Example 3, 150 g of Duolite C255LFH (cation exchange resin, manufactured by Sumika Chemtex Co., Ltd.) was added and stirred for 1 hour, followed by filtration to remove the ion exchange resin, yielding a 4.0 mass% polystyrene sulfonic acid aqueous solution. The sodium concentration was 40 ppm (10 ppm per 1.0 mass% PSS) and sulfate ion concentration was 664 ppm (166 ppm per 1.0 mass% PSS).

[0106] Example 4: Preparation of conductive polymer dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "312.5 g of a 4.0 mass% polystyrene sulfonic acid aqueous solution and 523.7 g of ion-exchanged water" in Production Example 4. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0107] (Production Example 5) Production of polystyrene sulfonic acid To 500 g of the 4.0 mass% polystyrene sulfonic acid aqueous solution obtained in Production Example 4, 100 g of Duolite C255LFH (cation exchange resin, manufactured by Sumika Chemtex Co., Ltd.) was added and stirred for 1 hour, and then the ion exchange resin was removed by filtration to obtain a 3.0 mass% polystyrene sulfonic acid aqueous solution. The sodium concentration was 6 ppm (2 ppm per 1.0 mass% PSS), and the sulfate ion concentration was 528 ppm (176 ppm per 1.0 mass% PSS).

[0108] Example 5: Preparation of conductive polymer dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "416.7 g of a 3.0 mass% polystyrene sulfonic acid aqueous solution and 419.5 g of ion-exchanged water" in Production Example 5. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0109] (Example 6) Preparation of conductive polymer dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "375 g of a 4.0 mass% polystyrene sulfonic acid aqueous solution and 461.2 g of ion-exchanged water" in Production Example 4. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0110] (Production Example 6) Production of polystyrene sulfonic acid A 5.0% by mass aqueous polystyrene sulfonic acid solution containing PSS with a weight-average molecular weight of 299,000 was obtained in the same manner as in Production Example 1, except that the amount of "3 g of sodium persulfate" in Production Example 1 was changed to 1 g. The sodium concentration was 115 ppm (23 ppm per 1.0% by mass of PSS) and the sulfate ion concentration was 375 ppm (75 ppm per 1.0% by mass of PSS).

[0111] Example 7 Preparation of Conductive Polymer Dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "250 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 586.2 g of ion-exchanged water" in Production Example 6. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0112] (Production Example 7) Production of polystyrene sulfonic acid A 5.0% by mass aqueous polystyrene sulfonic acid solution containing PSS with a weight-average molecular weight of 625,000 was obtained in the same manner as in Production Example 1, except that the amount of "3 g of sodium persulfate" in Production Example 1 was changed to 0.3 g. The sodium concentration was 150 ppm (30 ppm per 1.0% by mass of PSS) and the sulfate ion concentration was 305 ppm (61 ppm per 1.0% by mass of PSS).

[0113] (Example 8) Preparation of Conductive Polymer Dispersion 8 A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "200 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 636.2 g of ion-exchanged water" in Production Example 7. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0114] (Comparative Production Example 1) Production of polystyrene sulfonic acid 100 g of sodium styrenesulfonate was dissolved in 800 ml of ion-exchanged water, and while stirring at 80°C, 3 g of an oxidizing agent solution of sodium persulfate previously dissolved in 100 ml of water was added dropwise at a constant rate over 120 minutes. The solution was stirred for a further 2 hours, and then 1.5 g of an oxidizing agent solution of sodium persulfate previously dissolved in 50 ml of water was added dropwise at a constant rate over 60 minutes. The solution was stirred for a further 1 hour and then cooled to 25°C. To the resulting sodium polystyrene sulfonate solution, 300 g of Duolite C255LFH (Sumika Chemtex Corporation, cation exchange resin) was added and stirred for 1 hour. The ion exchange resin was then removed by filtration. The resulting solution was then adjusted to 5.0% by mass with ion-exchanged water to obtain a polystyrene sulfonate aqueous solution containing PSS with a weight-average molecular weight of 176,000. The sodium concentration was 260 ppm (52 ​​ppm per 1.0% by mass of PSS) and the sulfate ion concentration was 1425 ppm (285 ppm per 1.0% by mass of PSS).

[0115] (Comparative Example 1) Preparation of Conductive Polymer Dispersion The procedure was the same as Example 1 except that "300.0 g of a 5.0 mass % polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "5.0 mass % polystyrene sulfonic acid aqueous solution" in Comparative Production Example 1, and a 1.3 mass % conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as Example 1. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0116] (Comparative Production Example 2) Production of polystyrene sulfonic acid A 5.0% by mass aqueous polystyrene sulfonic acid solution containing PSS with a weight-average molecular weight of 107,000 was obtained in the same manner as Comparative Production Example 1, except that the amount of "3 g of sodium persulfate" in Comparative Production Example 1 was changed to 9 g. The sodium concentration was 390 ppm (78 ppm per 1.0% by mass of PSS) and the sulfate ion concentration was 3,255 ppm (651 ppm per 1.0% by mass of PSS).

[0117] (Comparative Example 2) Preparation of Conductive Polymer Dispersion A 1.3 mass % conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Comparative Example 1, except that the polystyrene sulfonic acid aqueous solution of Comparative Production Example 1 was replaced with the polystyrene sulfonic acid aqueous solution of Comparative Production Example 2. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0118] (Comparative Production Example 3) Production of polystyrene sulfonic acid A 5.0% by mass aqueous polystyrene sulfonic acid solution containing PSS with a weight-average molecular weight of 250,000 was obtained in the same manner as Comparative Production Example 1, except that the amount of "3 g of sodium persulfate" in Comparative Production Example 1 was changed to 2 g. The sodium concentration was 220 ppm (44 ppm per 1.0% by mass of PSS) and the sulfate ion concentration was 810 ppm (162 ppm per 1.0% by mass of PSS).

[0119] (Comparative Example 3) Preparation of Conductive Polymer Dispersion A 1.3 mass % conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Comparative Example 1, except that the polystyrene sulfonic acid aqueous solution of Comparative Production Example 1 was replaced with the polystyrene sulfonic acid aqueous solution of Comparative Production Example 3. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0120] (Comparative Example 4) Preparation of Conductive Polymer Dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "250 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 586.2 g of ion-exchanged water" in Comparative Production Example 3. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0121] (Comparative Production Example 4) Production of polystyrene sulfonic acid A 5.0% by mass aqueous polystyrene sulfonic acid solution containing PSS with a weight-average molecular weight of 299,000 was obtained in the same manner as Comparative Production Example 1, except that the amount of "3 g of sodium persulfate" in Comparative Production Example 1 was changed to 1 g. The sodium concentration was 165 ppm (33 ppm per 1.0% by mass of PSS) and the sulfate ion concentration was 405 ppm (81 ppm per 1.0% by mass of PSS).

[0122] (Comparative Example 5) Preparation of Conductive Polymer Dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "250 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 586.2 g of ion-exchanged water" in Comparative Production Example 4. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0123] (Comparative Production Example 5) Production of polystyrene sulfonic acid A 5.0% by mass aqueous polystyrene sulfonic acid solution containing PSS with a weight-average molecular weight of 625,000 was obtained in the same manner as Comparative Production Example 1, except that the amount of "3 g of sodium persulfate" in Comparative Production Example 1 was changed to 0.3 g. The sodium concentration was 205 ppm (41 ppm per 1.0% by mass of PSS) and the sulfate ion concentration was 330 ppm (66 ppm per 1.0% by mass of PSS).

[0124] (Comparative Example 6) Preparation of Conductive Polymer Dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was replaced with "200 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 636.2 g of ion-exchanged water" in Comparative Production Example 5. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0125] (Comparative Production Example 7) Production of polystyrene sulfonic acid 50 g of DUOLITE A368MS (anion exchange resin, manufactured by Sumika Chemtex Corporation) was added to 500 g of the 5.0% by weight polystyrene sulfonic acid aqueous solution containing PSS with a weight-average molecular weight of 176,000 (Comparative Production Example 1), stirred for 1 hour, and then filtered to remove the ion exchange resin. The solution was then adjusted to 4.0% by weight with ion-exchanged water to obtain a polystyrene sulfonic acid aqueous solution containing PSS with a weight-average molecular weight of 173,000. The sodium concentration was 40 ppm (10 ppm per 1.0% by weight of PSS), and the sulfate ion concentration was below the detection limit of 1 ppm (less than 1 ppm per 1.0% by weight of PSS).

[0126] (Comparative Example 7) Preparation of conductive polymer dispersion A 1.3 mass% conductive polymer (PEDOT-PSS) dispersion was obtained in the same manner as in Example 1, except that "300.0 g of a 5.0 mass% polystyrene sulfonic acid aqueous solution and 536.2 g of ion-exchanged water" in Production Example 1 was changed to "375 g of a 4.0 mass% polystyrene sulfonic acid aqueous solution and 461.2 g of ion-exchanged water" in Comparative Production Example 7. The resulting conductive polymer dispersion was analyzed by gas chromatography (GC), and the amount of unpolymerized EDOT was found to be below the detection limit.

[0127] <Surface resistance measurement> DMSO (dimethyl sulfoxide) was added in an amount of 5% by mass to the conductive polymer dispersion (concentration: 1.3% by mass) prepared in each example, and then the mixture was diluted with methanol to twice the volume to obtain a coating material. The above coating material was applied to a PET film (DIAFOIL T680E100 manufactured by Mitsubishi Chemical Corporation) using a #8 bar coater, and then dried in a hot air dryer at 100°C for 1 minute. The surface resistance value (unit: Ω / □) of the obtained conductive film was measured using Loresta (Loresta GP MCP-T610, manufactured by Nitto Seiko Analytech Co., Ltd.).

[0128] <Transmittance measurement> The total light transmittance of the conductive film used in measuring the surface resistance value was measured using a haze meter NDH5000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0129] [Table 1]

[0130] [Table 2]

[0131] In the manufacturing method of the conductive polymer dispersion of the example according to the present invention, the sodium ion concentration and sulfate ion concentration in the PSS aqueous solution added to the polymerization reaction solution of the π-conjugated conductive polymer monomer were within specific ranges, so a conductive polymer dispersion capable of forming a conductive layer with good transparency and excellent conductivity was obtained. Similar results were obtained over a wide range of weight-average molecular weights of the PSS contained in the PSS aqueous solution. The conductive polymer dispersion produced by the method according to the present invention exhibits excellent conductivity as described above, and therefore, when used as a material for the solid electrolyte layer of a capacitor, a solid electrolyte layer with excellent conductivity can be formed, and a capacitor with excellent performance such as equivalent series resistance can be obtained. [Explanation of symbols]

[0132] 10 Capacitors 11 Anode 12 Dielectric layer 13 Cathode 14 Solid electrolyte layer

Claims

1. A method for producing a conductive polymer dispersion, the method comprising the steps of: forming a conductive complex containing the π-conjugated conductive polymer and the polyanion by polymerizing the monomer in a reaction liquid obtained by blending an aqueous polyanion solution containing a polyanion and water, a monomer that forms a π-conjugated conductive polymer, and other optional components; and obtaining a conductive polymer dispersion in which the conductive complex is dispersed in an aqueous dispersion medium, the method comprising the steps of: The method for producing a conductive polymer dispersion liquid, wherein the aqueous polyanion solution satisfies the following condition A: <Condition A> The concentration of sodium ions in the aqueous polyanion solution is 30 ppm or less per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, and the concentration of sulfate ions in the aqueous polyanion solution is 60 ppm or more per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, relative to the total mass of the aqueous polyanion solution.

2. The method for producing a conductive polymer dispersion according to claim 1 , wherein the aqueous polyanion solution further satisfies the following condition B: <Condition B> The concentration of sodium ions in the aqueous polyanion solution is 2 ppm or more per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, and the concentration of sulfate ions in the aqueous polyanion solution is 600 ppm or less per 1.0 mass % of the polyanion contained in the aqueous polyanion solution, relative to the total mass of the aqueous polyanion solution.

3. The method for producing a conductive polymer dispersion according to claim 2 , wherein the content of water relative to the total mass of the conductive polymer dispersion is 70 mass % or more.

4. a preliminary step of radically polymerizing a monomer that forms the polyanion in the presence of water to obtain the aqueous polyanion solution, 4. The method for producing a conductive polymer dispersion according to claim 3, wherein in the preliminary step, a persulfate is used to initiate the radical polymerization, and sulfate ions are produced as a by-product.

5. The method for producing a conductive polymer dispersion according to claim 4 , wherein the sulfate ions contained in the aqueous polyanion solution are removed before the aqueous polyanion solution is added to the reaction liquid.

6. The method for producing a conductive polymer dispersion according to claim 5 , wherein the weight average molecular weight of the polyanion is 100,000 or more and 1,000,000 or less.

7. The method for producing a conductive polymer dispersion according to claim 6 , wherein the polyanion is polystyrene sulfonic acid.

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

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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