Production method of conductive polymer dispersion, as well as production method of conductive laminate and production method of capacitor

Abstract

To provide: a production method of a conductive polymer dispersion having low viscosity and containing a conductive composite body with a small particle size; a production method of a conductive laminate containing a cured product of the conductive polymer dispersion; and a production method of a capacitor.SOLUTION: A production method of a conductive polymer dispersion has a polymerization step to form a conductive composite body containing a π-conjugated conductive polymer and a polyanion by polymerizing a monomer forming the π-conjugated conductive polymer in a reaction mixture containing the polyanion, a cationic surface active agent and an aqueous dispersion. The cationic surface active agent is preferably one or more kinds selected from lauryl trimethylammonium, benzil dimethyl tetradecyl ammonium, benzil cetyl dimethyl ammonium, benzil dodecyl dimethyl ammonium, benzil trimethyl ammonium, and salts thereof.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, and a method for producing a conductive laminate and a method for producing a capacitor.

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For the conductive polymer dispersion used in the production of a capacitor, it is required to have a low viscosity and small particle size of the contained conductive composite in order to penetrate into the porous structure of the dielectric layer. Furthermore, the conductive layer (solid electrolyte layer) formed by drying the infiltrated conductive polymer dispersion is also required to have high conductivity. In addition, the conductivity of a conductive layer, which is a cured product of a conventional conductive polymer dispersion, has problems such as a decrease in conductivity when exposed to high temperatures for a long time, or an increase in equivalent series resistance (ESR) in the case of a capacitor. Such a decrease in conductivity or an increase in ESR leads to deterioration of the performance of capacitors and the like, and thus improvement has been demanded.

[0005] The present invention provides a method for producing a conductive polymer dispersion containing a conductive composite with a small particle size and having a low viscosity, a method for producing a conductive laminate, and a method for producing a capacitor. [Means for Solving the Problems]

[0006] [1] A method for producing a conductive polymer dispersion, comprising a polymerization step of forming a conductive composite containing the π-conjugated conductive polymer and the polyanion by polymerizing a monomer that forms a π-conjugated conductive polymer in a reaction solution containing a polyanion, a cationic surfactant, and an aqueous dispersion medium. [2] The method for producing a conductive polymer dispersion according to [1], wherein the conductive polymer dispersion contains a conductive composite containing the π-conjugated conductive polymer and the polyanion, an aqueous dispersion medium, and the cationic surfactant. [3] The method for producing a conductive polymer dispersion according to [1] or [2], wherein the cationic surfactant is a tertiary amine or a quaternary ammonium or a salt thereof. [4] The method for producing a conductive polymer dispersion according to any one of [1] to [3], wherein the cationic surfactant has a chemical structure represented by the following formula (1) or (2). [5] The method for producing a conductive polymer dispersion according to any one of [1] to [4], wherein the cationic surfactant has a chemical structure represented by the following formula (3). [6] The method for producing a conductive polymer dispersion according to any one of [1] to [5], wherein the cationic surfactant is at least one selected from lauryltrimethylammonium, benzyldimethyltetradecylammonium, benzylcetyldimethylammonium, benzyldodecyldimethylammonium, benzyltrimethylammonium, and salts thereof. [7] The method for producing a conductive polymer dispersion according to any one of [1] to [6], wherein the π-conjugated system 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: 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 at least a part of the surface of a substrate and drying to form a conductive layer.

[10] A method for producing a capacitor, comprising: an anode made of a porous body of valve metal; a dielectric layer made of an oxide of the valve metal; a cathode made of a conductive material provided on the side opposite to the anode of the dielectric layer; and a solid electrolyte layer formed between the dielectric layer and the cathode. The method includes: 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 the surface of the dielectric layer and drying to form the solid electrolyte layer. [Advantages of the Invention]

[0007] The conductive polymer dispersion obtained by the production method of the present invention contains conductive composites with small particle sizes and has a low viscosity, so it is suitable for the production of conductive laminates and capacitors. In addition, the conductive layer made of the cured product of the conductive polymer dispersion according to the present invention not only has good conductivity but also excellent heat resistance, so the performance of the conductive laminate and capacitor provided with the conductive layer is excellent.

[0008] The present invention is considered to contribute to SDGs Goal 12, "Responsibility to Produce and Responsibility to Use".

[0009] In this specification and the claims, the lower and upper limit values of the numerical range indicated by "~" are included in the numerical range. [Brief Description of the Drawings]

[0010]

Figure 1

Mode for Carrying Out the Invention

[0011] ≪Conductive Polymer Dispersion Liquid≫ The first aspect of the present invention is a conductive polymer dispersion liquid containing a conductive composite containing a π-conjugated conductive polymer and a polyanion, an optionally contained cationic surfactant, and an aqueous dispersion medium.

[0012] <Conductive Composite> The conductive composite of this aspect contains a π-conjugated conductive polymer and a polyanion. The polyanion in the conductive composite dopes the π-conjugated conductive polymer to form a conductive composite having conductivity. In the polyanion, only some of the anion groups dope the π-conjugated conductive polymer, and it has surplus anion groups that do not participate in the doping. Since the surplus anion groups are hydrophilic groups, the conductive composite has water dispersibility. When the number of all anion groups of the polyanion is set to 100 mol%, the surplus anion groups are preferably 30 mol% or more and 90 mol% or less, and more preferably 45 mol% or more and 75 mol% or less.

[0013] (π-Conjugated Conductive Polymer) The π-conjugated conductive polymer may be an organic polymer whose main chain is composed of a π-conjugated system. For example, 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 can be mentioned. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophenes, and polyaniline-based conductive polymers are preferable, and from the viewpoint of transparency, polythiophene-based conductive polymers are more preferable.

[0014] Examples of polythiophene-based conductive polymers include polythiophene, poly(3-methylthiophene), poly(3-ethylthiophene), poly(3-propylthiophene), poly(3-butylthiophene), poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-octadecylthiophene), poly(3-bromothiophene), poly(3-chlorothiophene), poly(3-iodothiophene), poly(3-cyanothiophene), poly(3-phenylthiophene), poly(3,4-dimethylthiophene), poly(3,4-dibutylthiophene), poly(3-hydroxy-thiophene), poly(3-methoxythiophene), poly(3-ethoxythiophene), poly(3-butoxythiophene), poly(3-hexyloxythiophene), poly(3-heptyloxythiophene), poly(3-octyloxythiophene), poly(3-decyloxythiophene), poly(3-dodecyloxythiophene), poly(3-octadecyloxythiophene), poly(3,4-dihydroxy-thiophene), 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-didodecyloxythiophene), 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 π-conjugated conductive polymer contained in the conductive composite may be one type or two or more types.

[0015] (Polyanion) A polyanion is a polymer having two or more monomer units with anionic groups in the molecule. The anionic groups of this polyanion function as dopants for the π-conjugated conductive polymer and improve 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 polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylate esters having a sulfo group, polymethacrylate esters having a sulfo group (for example, poly(4-sulfobutyl methacrylate), polysulfoethyl methacrylate, polymethacryloyloxybenzene sulfonic acid), polymers having a sulfo group such as poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and polymers having a carboxy group such as polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacrylic acid, polymethacrylic acid, poly(2-acrylamido-2-methylpropane carboxylic acid), polyisoprene carboxylic acid. The polyanion may be a homopolymer obtained by polymerizing a single monomer or a copolymer obtained by polymerizing two or more monomers. Among these polyanions, polymers having a sulfo group are preferred and polystyrene sulfonic acid is more preferred because they can achieve higher conductivity.

[0016] The content ratio of the polyanion contained in the conductive composite of this embodiment is preferably in the range of, for example, 1 part by mass or more and 1000 parts by mass or less, more preferably 10 parts by mass or more and 700 parts by mass or less, and even more preferably 100 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the π-conjugated conductive polymer. If the content ratio of the polyanion is equal to or higher than the lower limit value, the doping effect on the π-conjugated conductive polymer tends to be stronger and the conductivity becomes higher. On the other hand, if the content of the polyanion is equal to or lower than the upper limit value, the content ratio of the π-conjugated conductive polymer becomes sufficient, so that sufficient conductivity can be ensured.

[0017] The total content of the π-conjugated conductive polymer and the polyanion (i.e., the content of the conductive composite) with respect to the total mass of the conductive polymer dispersion of this embodiment is preferably 0.1% by mass or more and 5.0% by mass or less, more preferably 0.5% by mass or more and 2.5% by mass or less, and even more preferably 0.8% by mass or more and 2.0% by mass or less. When it is within the above-mentioned suitable range, the dispersibility of the conductive composite is enhanced, and the coatability is improved. Further, the ESR of a capacitor having a solid electrolyte layer formed from the conductive polymer dispersion can be further reduced. Further, the antistatic property and the like of a conductive laminate having a conductive layer formed from the conductive polymer dispersion can be further improved.

[0018] (Cationic surfactant) Since the conductive polymer dispersion of this embodiment contains a cationic surfactant at least in the production process, its viscosity can be reduced, and the particle size of the conductive composite can be made smaller. Further, the ESR of a capacitor having a solid electrolyte layer formed from the conductive polymer dispersion can be further reduced, and its heat resistance can also be improved. Further, the antistatic property and heat resistance of a conductive laminate having a conductive layer formed from the conductive polymer dispersion can be further improved.

[0019] From the viewpoint of sufficiently obtaining the above effects, the cationic surfactant is preferably a tertiary amine or a quaternary ammonium or a salt thereof, and a cationic surfactant having a chemical structure represented by any of the following formulas (1) to (3) is more preferable.

[0020] [Chemical formula]

[0021] In formulas (1) to (3), R 1 , R 2 , R 3 , R 4 , R 5 , R 6 each independently represents an alkyl group having 1 to 20 carbon atoms or a benzyl group, and A represents a halide ion or a hydroxide ion.

[0022] R 1 , R 2 , R 3When any one or more of them represent an alkyl group, each alkyl group is preferably linear, and its carbon number is preferably 1 to 15, more preferably 1 to 13, and even more preferably 1 to 11. R 4 ,R 5 When any one or more of them represent an alkyl group, each alkyl group is preferably linear, and its carbon number is preferably 1 to 15, more preferably 1 to 13, and even more preferably 1 to 11. R 6 represents an alkyl group having 1 to 20 carbon atoms, preferably a linear alkyl group, and its carbon number is preferably 1 to 15, more preferably 1 to 13, and even more preferably 1 to 11.

[0023] Specific preferred cationic surfactants include, for example, benzyl dimethyl tetradecyl ammonium chloride, benzyl cetyl dimethyl ammonium chloride, benzyl dodecyl dimethyl ammonium chloride, benzyl dodecyl dimethyl ammonium bromide, benzyl trimethyl ammonium chloride, lauryl trimethyl ammonium chloride, and the like.

[0024] The content of the cationic surfactant relative to the total mass of the conductive polymer dispersion may be below the detection limit, but may be included, for example, in the range of 0.001% by mass or more and 1.0% by mass or less, preferably 0.50% by mass or less, and more preferably 0.30% by mass or less. When it is above the above lower limit value, the viscosity of the conductive polymer dispersion can be further reduced, and the particle size of the conductive composite can be made smaller. Further, the heat resistance of the conductive layer and the solid electrolyte layer can be further improved. When it is below the above upper limit value, the foaming of the conductive polymer dispersion can be reduced, and the decrease in the conductivity of the conductive layer, which is a cured product thereof, can be reduced.

[0025] (Dispersion medium) Since the conductive composite is hydrophilic, the dispersion medium contained in the conductive polymer dispersion is an aqueous dispersion medium containing water. Further, it 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. The conductive composite has an excess anion group derived from a polyanion and has high dispersibility in water. Therefore, as the dispersion medium other than water, a water-soluble organic solvent is preferable. Here, the water-soluble organic solvent is an organic solvent having a solubility of 1 g or more in 100 g of water at 20 °C. Examples thereof include alcohol solvents, ketone solvents, and ester solvents. The water-soluble organic solvent contained as the dispersion medium may be one kind or two or more kinds.

[0026] Examples of the alcohol solvent 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, ethylene glycol monomethyl ether, and the like. Examples of the ether solvent include diethyl ether, dimethyl ether, propylene glycol dialkyl ether, diethylene glycol diethyl ether, and the like. Examples of the ketone solvent include diethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisopropyl ketone, methyl ethyl ketone, acetone, diacetone alcohol, and the like. Examples of the nitrogen atom-containing solvent include N-methylpyrrolidone, dimethylacetamide, dimethylformamide, and the like. The water-soluble organic solvent may contain only one kind or two or more kinds. Since the wettability of the conductive polymer dispersion with respect to the base material is improved, as the water-soluble organic solvent, an alcohol solvent or a ketone solvent is preferable, and an alcohol solvent is more preferable.

[0027] The water content relative to the total mass of the dispersion medium excluding the solid content (non-volatile component) of the conductive polymer dispersion is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and may even be 100% by mass. When water is contained in an amount not less than the above lower limit value, the dispersibility of the conductive composite contained in the conductive polymer dispersion is enhanced, and the coatability is improved. Further, the ESR of a capacitor having a solid electrolyte layer formed from the conductive polymer dispersion can be further reduced. Further, the antistatic property and the like of a conductive laminate having a conductive layer formed from the conductive polymer dispersion can be further improved.

[0028] The content of the water-soluble organic solvent relative to the total mass of the aqueous dispersion medium is preferably 30 to 70% by mass, more preferably 40 to 60% by mass or more. Also, the content of water relative to the total mass of the aqueous dispersion medium is preferably 70 to 30% by mass, more preferably 60 to 40% by mass or less. When it is within the above preferable range, it is possible to improve the wettability with respect to a substrate while suppressing a decrease over time in the dispersion stability of the conductive composite in the conductive polymer dispersion.

[0029] When the concentration of the conductive composite with respect to the total mass of the conductive polymer dispersion is adjusted to 1.6% by mass, the initial viscosity (viscosity within 1 day after production) of the conductive polymer dispersion at 23°C is preferably 50 mPa·s or less, more preferably 40 mPa·s or less, still more preferably 30 mPa·s or less, and particularly preferably 25 mPa·s or less. The lower limit value of the above viscosity is not particularly limited, and examples of a standard include 1 mPa·s or more. When measuring the above viscosity, it is preferable that the dispersion medium contained in the conductive polymer dispersion is only ion-exchanged water. Further, the conductive polymer dispersion for measuring the viscosity contains a cationic surfactant, and it is preferable that no other additives are contained. The above viscosity measurement is a value measured at 23°C in accordance with JIS Z8803:2011 (Viscosity measurement method by vibrating viscometer) using a tuning fork vibration type viscometer.

[0030] (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, the polyanion, and the cationic surfactant. By containing the polyol compound, the ESR of a capacitor having a solid electrolyte layer formed from the conductive polymer dispersion can be further reduced. Also, the antistatic property and the like of a conductive laminate having a conductive layer formed from the conductive polymer dispersion can be further improved.

[0031] Examples of the polyol compound include one or more selected from ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, glycerin, pentaerythritol, trimethylolpropane, trimethylolethane, and polyethylene glycol.

[0032] The content of the polyol compound contained in the conductive polymer dispersion is preferably, for example, 100 parts by mass or more and 10,000 parts by mass or less, more preferably 200 parts by mass or more and 2,000 parts by mass or less, and even more preferably 300 parts by mass or more and 1,000 parts by mass or less with respect to a total of 100 parts by mass of the π-conjugated conductive polymer and the polyanion. When it is in the above preferable range, the coatability of the conductive polymer dispersion is improved, and the ESR of the capacitor can be further reduced. Also, the conductivity of the conductive layer can be further improved.

[0033] The content of the polyol compound with respect to the total mass of the conductive polymer dispersion is preferably 1% by mass or more and 18% by mass or less, more preferably 1% by mass or more and 10% by mass or less, and even more preferably 1% by mass or more and 5% by mass or less. When it is in the above preferable range, the coatability of the conductive polymer dispersion is improved, and the ESR of the capacitor can be further reduced. Also, the conductivity of the conductive layer can be further improved.

[0034] (Nitrogen-containing aromatic compound) The conductive polymer dispersion may contain one or more nitrogen-containing aromatic compounds. Here, the nitrogen-containing aromatic compound refers to an aromatic compound in which at least one nitrogen atom forms a ring structure. By containing the nitrogen-containing aromatic compound, the ESR of a capacitor having a solid electrolyte layer formed from the conductive polymer dispersion can be further reduced. In addition, the antistatic property and the like of a conductive laminate having a conductive layer formed from the conductive polymer dispersion can be further improved.

[0035] Examples of the nitrogen-containing aromatic compound include pyrrole, indole, imidazole, 2-methylimidazole, 2-propylimidazole, N-methylimidazole, N-propylimidazole, N-butylimidazole, 1-(2-hydroxyethyl)imidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-acetylimidazole, 2-aminobenzimidazole, 2-amino-1-methylbenzimidazole, 2-hydroxybenzimidazole, 2-(2-pyridyl)benzimidazole, pyridine, pyrimidine, pyrazine, and derivatives thereof such as alkyl-substituted products (for example, products substituted with an alkyl group having 1 to 4 carbon atoms such as methyl, ethyl, propyl, and butyl), halogen-substituted products (for example, products substituted with a halogen group such as fluoro, chloro, and bromo), and nitrile-substituted products. Among them, imidazole is more preferable.

[0036] The content of the nitrogen-containing aromatic compound contained in the conductive polymer dispersion is preferably, for example, 1 part by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 50 parts by mass or less, and still more preferably 15 parts by mass or more and 30 parts by mass or less with respect to a total of 100 parts by mass of the π-conjugated conductive polymer and the polyanion. When it is in the above preferable range, the ESR of the capacitor can be further reduced. In addition, the conductivity of the conductive layer can be further improved.

[0037] The content of the nitrogen-containing aromatic compound relative to the total mass of the conductive polymer dispersion is preferably 0.01% by mass or more and 1.0% by mass or less, more preferably 0.10% by mass or more and 0.60% by mass or less, and still more preferably 0.15% by mass or more and 0.40% by mass or less. When it is within the above-mentioned preferred range, the ESR of the capacitor can be further reduced. In addition, the conductivity of the conductive layer can be further improved.

[0038] (Optional additive) The conductive polymer dispersion of this aspect may contain any additive other than the conductive composite within the range not impairing the gist of the present invention, and the content ratio thereof can be appropriately determined according to the type of the additive, but for a total of 100 parts by mass of the π-conjugated conductive polymer and the polyanion, for example, it can be 1 to 1000 parts by mass. Here, the optional additive is a compound other than the cationic surfactant, the polyol compound, and the dispersion medium.

[0039] Examples of the optional additive include surfactants, inorganic conductive agents, defoaming agents, coupling agents, antioxidants, ultraviolet absorbers, and the like. Examples of the surfactant include nonionic, anionic, and cationic surfactants, and nonionic surfactants are preferred from the viewpoint of storage stability. In addition, polymer surfactants such as polyvinyl alcohol and polyvinyl pyrrolidone may be added. Examples of the inorganic conductive agent include metal ions and conductive carbon. Metal ions can be generated by dissolving a metal salt in water. Examples of the defoaming agent include silicone resins, 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 phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, and saccharides. 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, benzoate-based ultraviolet absorbers, and the like.

[0040] ≪Method for Producing Conductive Polymer Dispersion≫ A second aspect of the present invention is a method for producing a conductive polymer dispersion having a polymerization step of forming a conductive composite containing the π-conjugated conductive polymer and the polyanion by polymerizing a monomer that forms a π-conjugated conductive polymer in a reaction solution containing a polyanion, a cationic surfactant, and an aqueous dispersion medium. According to this aspect, the conductive polymer dispersion of the first aspect can be produced.

[0041] <Preparation of Polyanion> The polyanion used in the polymerization step can be prepared by a conventional method. For example, a polymerization initiator is added to a reaction solution containing a polymerizable anionic monomer and water to obtain an aqueous solution containing a polyanion formed by polymerization of the polymerizable anionic monomer.

[0042] The polymerizable anionic monomer is an organic compound that forms a polyanion upon polymerization and has at least one anion group in one molecule. The anion 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 that can form the polyanions exemplified above. Among them, styrene sulfonic acid or a salt thereof, which can form polystyrene sulfonic acid, which is particularly excellent as a dopant for π-conjugated conductive polymers, is most preferred. The blending amount of the polymerizable anionic monomer with respect to the total mass of the reaction solution is preferably, for example, 1.0 to 20.0% by mass, more preferably 5.0 to 15.0% by mass, and even more preferably 8.0 to 13.0% by mass.

[0043] Examples of the polymerization initiator include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. The compounding amount of the polymerization initiator relative to the total mass of the reaction solution is, for example, 0.1 to 1.0% by mass.

[0044] The completion of the polymerization reaction of the polyanion in the reaction solution is judged by the fact that all the polymerization initiator added to the reaction solution has been consumed. For example, when reacting with stirring at 70 to 95 ° C, the reaction can be completed in about 4 to 12 hours.

[0045] When the anion group of the polyanion obtained above forms a salt with a counter cation, it is preferable to contact with a cation exchange resin to remove the cation.

[0046] <Polymerization step> A conductive composite is obtained by forming a π-conjugated conductive polymer by a polymerization reaction in a reaction solution containing a polyanion, a cationic surfactant, and an aqueous dispersion medium. For example, a cationic surfactant, a polymerizable monomer for forming a π-conjugated conductive polymer, and an optional radical polymerization initiator are added to an aqueous polyanion solution, and by forming the π-conjugated conductive polymer, a dispersion of a conductive composite in which the π-conjugated conductive polymer and the polyanion are complexed can be obtained. In the polymerization step, it can be carried out by a known method except for polymerizing the π-conjugated conductive polymer in the presence of a polyanion and a cationic surfactant.

[0047] When the cationic surfactant used in the polymerization step has a counter anion, it may be contacted with an anion exchange resin to remove or reduce the counter anion before adding it to the reaction solution. By this treatment, adverse effects on the capacitance and ESR of the capacitor manufactured using the conductive polymer dispersion can be prevented.

[0048] The content of the cationic surfactant with respect to the total mass of the reaction solution during the polymerization reaction is preferably, for example, 0.01% by mass or more and 2.0% by mass or less, more preferably 0.05% by mass or more and 1.0% by mass or less, and still more preferably 0.10% by mass or more and 0.50% by mass or less. When it is not less than the above lower limit value, the particle size of the formed conductive composite can be made smaller. When it is not more than the above upper limit value, the foaming of the reaction solution can be reduced, and the excess cationic surfactant contained in the obtained conductive polymer dispersion can be reduced.

[0049] The polymerizable monomer for forming the π-conjugated conductive polymer is preferably one or more selected from known monomers capable of forming the π-conjugated conductive polymers exemplified above. Among them, 3,4-ethylenedioxythiophene capable of forming PEDOT with excellent conductivity and heat resistance is most preferred.

[0050] The compounding amount of the monomer with respect to the total mass of the reaction solution is preferably, for example, 0.01% by mass or more and 2.0% by mass or less, more preferably 0.1% by mass or more and 1.0% by mass or less, and still more preferably 0.4% by mass or more and 0.7% by mass or less. The compounding amount of the polyanion with respect to the total mass of the reaction solution is preferably, for example, 0.1% by mass or more and 3.0% by mass or less, more preferably 0.5% by mass or more and 2.0% by mass or less, and still more preferably 1.0% by mass or more and 1.5% by mass or less. By setting it within the above-mentioned suitable range, a conductive polymer dispersion in which the concentration of the conductive composite is the above-mentioned suitable content can be easily obtained.

[0051] Examples of the radical polymerization initiator include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate. It is preferable to incorporate a catalyst such as a transition metal compound such as ferric chloride, ferrous sulfate, ferric nitrate, and cupric chloride into the reaction solution together with the radical polymerization initiator.

[0052] As the compounding amount of the radical polymerization initiator with respect to the total mass of the reaction solution during the polymerization reaction, for example, 0.10% by mass or more and 1.00% by mass or less is preferable, 0.30% by mass or more and 0.80% by mass or less is more preferable, and 0.50% by mass or more and 0.70% by mass or less is even more preferable.

[0053] As the reaction temperature in the reaction solution, for example, it can be set to 20 to 30°C. At the above reaction temperature, the polymerization reaction is usually completed in about 4 to 12 hours. The completion of the polymerization reaction can be known by measuring the amount of unreacted monomer in the reaction solution by means such as gas chromatography. After the polymerization reaction, the reaction solution containing the conductive composite can be obtained as a conductive polymer dispersion.

[0054] It is preferable to remove the residues of the catalyst and the radical polymerization initiator added to the reaction solution from the conductive polymer dispersion after the polymerization reaction. Examples of the removal method include a method of bringing the conductive polymer dispersion into contact with an ion exchange resin to adsorb the catalyst and the radical polymerization initiator onto the ion exchange resin, and a method of removing the dispersion medium by ultrafiltration of the conductive polymer dispersion together with the replacement of the dispersion medium. Among these, the method using an ion exchange resin is preferable because it is simple. It is preferable to use a combination of a cation exchange resin and an anion exchange resin as the ion exchange resin.

[0055] By the treatment using the above cation exchange resin, part or all of the cationic surfactant in the conductive polymer dispersion may be adsorbed and removed by the cation exchange resin.

[0056] The obtained conductive polymer dispersion may be subjected to a dispersion treatment by a conventional method such as a high-pressure homogenizer.

[0057] To the conductive polymer dispersion obtained above, a cationic surfactant, a polyol compound, a nitrogen-containing aromatic compound, an arbitrary additive, etc. may be further added.

[0058] ≪Method for manufacturing a conductive laminate≫ A conductive laminate can be manufactured by a manufacturing method including a step of applying the conductive polymer dispersion liquid according to the first aspect of the present invention onto at least a part of the surface of a substrate to form a conductive layer.

[0059] As a method of applying (coating) the conductive polymer dispersion liquid onto an arbitrary surface of the substrate, for example, methods using coaters such as 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, screen coater, etc., methods using sprayers such as air spray, airless spray, rotor damping, etc., dipping methods such as dip, etc. can be applied.

[0060] The coating amount of the conductive polymer dispersion liquid on the substrate is not particularly limited, but for example, as a non-volatile component, a range of 0.01 to 10.0 g / m 2 is preferable.

[0061] A conductive layer can be formed by drying a coating film composed of the conductive polymer dispersion liquid applied on the substrate to remove at least a part of the dispersion medium and curing it. Examples of the method of drying the coating film include heat drying and vacuum drying. As heat drying, for example, methods such as hot air heating and infrared heating can be adopted. When applying heat drying, the heating temperature is appropriately set according to the dispersion medium to be used, but usually it is within the range of 50°C or higher and 200°C or lower. Here, the heating temperature is the set temperature of the drying device. As a preferable drying time within the above range of heating temperature, 0.5 minutes or more and 30 minutes or less is preferable, and 1 minute or more and 15 minutes or less is more preferable.

[0062] ≪Conductive laminate≫ The third aspect of the present invention is a conductive laminate including a substrate and a conductive layer formed on at least a part of the surface of the substrate, wherein the conductive layer contains a cured product of the conductive polymer dispersion liquid according to the second aspect.

[0063] [Conductive layer] The formation range of the conductive layer may be the entire surface or a part of any surface of the substrate. In the conductive film, it is preferable that a conductive layer with a substantially uniform thickness is formed on substantially the entire surface of one side or the other side of the film substrate. When the conductive layer is formed only on a part of the surface of the substrate, for example, the conductive layer may be a fine conductive pattern such as a circuit or an electrode, or the region where the conductive layer is provided and the region where it is not provided may exist on the same surface and be roughly divided.

[0064] As the average thickness of the conductive layer, for example, 10 nm or more and 100 μm or less is preferable, 20 nm or more and 50 μm or less is more preferable, and 30 nm or more and 30 μm or less is even more preferable. If the average thickness of the conductive layer is equal to or greater than the lower limit value, high conductivity can be exhibited, and if it is equal to or less than the upper limit value, the adhesion of the conductive layer to the substrate is further improved.

[0065] [Substrate] The substrate may be a substrate made of an insulating material or a substrate made of a conductive material. The shape of the substrate is not particularly limited, and examples include shapes mainly having a plane such as a film and a substrate. Examples of the insulating material include glass, synthetic resin, and ceramics. Examples of the conductive material include metal, conductive metal oxide, and carbon.

[0066] (Film substrate) When a film substrate is used as the substrate, the conductive laminate becomes a conductive film. Examples of the film base material include plastic films made of synthetic resins. Examples of the synthetic resin include 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 elastomer, polyester-based elastomer, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyimide, cellulose triacetate, cellulose acetate propionate, and the like. From the viewpoint of enhancing the adhesion between the film base material and the conductive layer, the synthetic resin for the film base material is preferably a polyester resin, and among them, polyethylene terephthalate is preferable.

[0067] The synthetic resin for the film base material may be amorphous or crystalline. The film base material may be unstretched or stretched. The film base material may be subjected to surface treatment such as corona discharge treatment, plasma treatment, flame treatment, etc. in order to further improve the adhesion of the conductive layer.

[0068] The average thickness of the film base material is preferably 5 μm or more and 500 μm or less, and more preferably 20 μm or more and 200 μm or less. If the average thickness of the film base material is at least the lower limit value, it becomes difficult to break, and if it is at most the upper limit value, sufficient flexibility as a film can be ensured. The average thickness of the film base material is a value obtained by measuring the thickness at 10 randomly selected locations and averaging the measured values.

[0069] (Glass substrate) Examples of the glass substrate include an alkali-free glass substrate, a soda-lime glass substrate, a borosilicate glass substrate, a fused silica glass substrate, etc. When the substrate contains an alkali component, the conductivity of the conductive layer tends to decrease. Therefore, among the above glass substrates, an alkali-free glass is preferred. Here, the alkali-free glass refers to a glass composition in which the content of the alkali component is 0.1% by mass or less based on the total mass of the glass composition.

[0070] The average thickness of the glass substrate is preferably 100 μm or more and 3000 μm or less, more preferably 100 μm or more and 1000 μm or less. If the average thickness of the glass substrate is equal to or greater than the lower limit value, it is less likely to be damaged, and if it is equal to or less than the upper limit value, it can contribute to thinning of the conductive laminate. The average thickness of the glass substrate is a value obtained by measuring the thickness at 10 randomly selected locations and averaging the measured values.

[0071] ≪Method for manufacturing a capacitor≫ A capacitor can be manufactured by a manufacturing method having a step of applying the conductive polymer dispersion of the first aspect to the surface of the dielectric layer formed on the surface of the anode made of the porous body of the valve metal and drying to form a solid electrolyte layer.

[0072] The method for manufacturing a capacitor preferably includes a step of oxidizing the surface of the anode made of the porous body of the valve metal to form a dielectric layer (dielectric formation step), a step of disposing a cathode at a position facing the dielectric layer (cathode formation step), and a step of forming a solid electrolyte layer on at least a part of the surface of the dielectric layer (film formation step). Hereinafter, each step will be described with reference to FIG. 1.

[0073] [Dielectric formation step] In this step, the surface of the anode 11 made of the porous body of the valve metal is oxidized to form a dielectric layer 12. The method for forming the dielectric layer 12 is not particularly limited, and examples thereof include a method of anodizing the surface of the anode 11 in an electrolytic solution for formation treatment such as an ammonium adipate aqueous solution, an ammonium borate aqueous solution, or an ammonium phosphate aqueous solution.

[0074] [Cathode Formation Process] In this process, the cathode 13 is disposed at a position facing the dielectric layer 12. The method of disposing the cathode 13 is not particularly limited. For example, there are methods of forming the cathode 13 using a conductive paste such as a carbon paste or a silver paste, and methods of disposing a metal foil such as an aluminum foil facing the dielectric layer 12, and the like.

[0075] [Film Formation Process] In this process, the solid electrolyte layer 14 is formed by applying the above-described conductive polymer dispersion liquid to at least a part of the surface of the dielectric layer 12 and drying it.

[0076] As a method of applying the conductive polymer dispersion liquid, for example, dipping (dip coating), comma coating, reverse coating, lip coating, microgravure coating, etc. can be applied. Among these, a method of dipping the anode 11 into the conductive polymer dispersion liquid under reduced pressure is preferable. When using the dipping method, the conductive polymer dispersion liquid can be sufficiently applied to the inside of the porous structure on the surface of the dielectric layer 12. After dipping, it is taken out and the next drying process is carried out.

[0077] As drying methods, for example, room temperature drying, hot air drying, far-infrared drying, etc. can be mentioned. Among these, hot air drying is preferable. As the drying temperature, for example, 100 to 180 °C is preferable, and 120 to 150 °C is more preferable. As the drying time, for example, 0.2 to 1 hour is preferable. After the drying process, the capacitor may be assembled by a conventional method.

[0078] ≪Capacitor≫ The fourth aspect of the present invention is a capacitor including an anode made of a porous body of valve metal, a dielectric layer made of an oxide of the valve metal, a cathode made of a conductive material provided on the opposite side of the dielectric layer from 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 liquid of the second aspect.

[0079] An example of an embodiment of the capacitor will be described with reference to FIG. 1. The capacitor 10 shown in FIG. 1 includes an anode 11 made of a porous body of valve metal, a dielectric layer 12 made of an oxide of valve metal, a solid electrolyte layer 14 formed on the surface of the dielectric layer 12, and a cathode 13 provided on the outermost side. The cathode 13 is provided on the side opposite to the anode 11 with the dielectric layer 12 and the solid electrolyte layer 14 interposed therebetween.

[0080] Examples of the valve metal constituting the anode 11 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Among these, aluminum, tantalum, and niobium are preferable. Specific examples of the anode 11 include those obtained by etching an aluminum foil to increase the surface area and then subjecting the surface to an oxidation treatment, and those obtained by subjecting the surface of a sintered body of tantalum particles or niobium particles to an oxidation treatment to form pellets. Those processed in this way become porous bodies with uneven surfaces formed thereon.

[0081] The dielectric layer 12 in the present embodiment is a layer formed by oxidizing the surface of the anode 11, and is formed, for example, by anodizing the surface of the metal anode 11 in an electrolytic solution such as an ammonium adipate aqueous solution. Similar to the anode 11, the dielectric layer 12 also has uneven surfaces formed thereon.

[0082] As the cathode 13 in the present embodiment, a metal layer made of a conductive substance such as a conductive layer formed from a conductive paste or an aluminum foil can be used.

[0083] The solid electrolyte layer 14 in the present embodiment is formed on the surface of the dielectric layer 12. The solid electrolyte layer 14 covers at least a part 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 be constant or may not be constant, and examples thereof include a thickness of 1 μm or more and 100 μm or less.

[0084] [Electrolytic solution] The capacitor may have an electrolytic solution that impregnates the solid electrolyte layer. Examples of the solvent constituting the electrolytic solution include alcohol solvents such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, and glycerin; lactone solvents such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; sulfur solvents such as sulfolane, dimethyl sulfoxide, and dimethyl sulfone; amide solvents such as N-methylformamide, N,N-dimethylformamide, N-methylacetamide, and N-methylpyrrolidinone; nitrile 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, 1,6-decanedicarboxylic acid, and 5,6-decanedicarboxylic acid; octanedicarboxylic acids such as 1,7-octanedicarboxylic acid; azelaic acid, sebacic acid, and other organic acids; or boric acid, a polyhydric alcohol complex compound of boric acid obtained from boric acid and a polyhydric alcohol; inorganic acids such as phosphoric acid, carbonic acid, and silicic acid, etc. as the anion component, 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 the cation component; and other electrolytes.

[0085] The capacitor is not limited to the above configuration, and a separator may be provided between the dielectric layer and the cathode. Examples of the capacitor with a separator provided between the dielectric layer and the cathode include a wound capacitor. Examples of the separator include sheets (including nonwoven fabrics) made of, for example, 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 or more and 1.0 g / cm 3 or less. When providing a separator, a method of impregnating the separator with carbon paste or silver paste to form a cathode can also be applied.

Example

[0086] (Production Example 1) Production of polystyrene sulfonic acid: Mw 175,000 110 g of sodium styrene sulfonate was dissolved in 820 ml of ion-exchanged water, and while stirring at 80°C, 4.88 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. A cation exchange resin was added to the obtained sodium polystyrene sulfonate-containing solution to remove sodium ions. The solid content of the obtained aqueous solution of polystyrene sulfonic acid (PSS) was 10% by mass. Regarding the PSS aqueous solution, using an HPLC (high performance liquid chromatography) system with a GPC (gel filtration chromatography) column, the weight average molecular weight was measured using pullulan manufactured by Showa Denko K.K. as a standard substance, and the result was 175,000.

[0087] <Example 1> An anion exchange resin was mixed into a 10% by mass aqueous solution of benzyl dodecyl dimethyl ammonium bromide to obtain benzyl dodecyl dimethyl ammonium as a cationic surfactant with reduced bromide. 5.71 g of 3,4-ethylenedioxythiophene, 136.98 g of the polystyrene sulfonic acid aqueous solution obtained in Production Example 1, 1.42 g of benzyldodecyldimethylammonium, and 780.01 g of ion-exchanged water were mixed at 26°C. While maintaining the obtained mixed solution at 26°C and stirring, an oxidation catalyst solution of 1.15 g of ferric sulfate dissolved in 18.04 g of ion-exchanged water was added, and 6.23 g of ammonium persulfate dissolved in 50.44 g of ion-exchanged water was gradually added dropwise over 2 hours, and further stirred for 4 hours to cause a reaction. A cation exchange resin and an anion exchange resin were put into the obtained reaction solution to remove at least a part of the polymerization initiator, the oxidation catalyst, and the cationic surfactant. Thereby, a blue PEDOT-PSS aqueous dispersion (conductive polymer dispersion) containing PEDOT:PSS = 1:2.5 (mass ratio) and a cationic surfactant was obtained. The solid content of the obtained dispersion was adjusted to 1.6% by mass by ultrafiltration.

[0088] The capacitor element obtained in Production Example 2 was immersed in the above PEDOT-PSS aqueous dispersion under reduced pressure, and then dried by a hot air dryer at 125°C for 30 minutes to form a solid electrolyte layer containing a conductive composite on the surface of the dielectric layer. Next, the capacitor element having the above solid electrolyte layer formed thereon was loaded into an aluminum case and sealed with a sealing rubber to fabricate a capacitor.

[0089] <Example 2> In Example 1, a conductive polymer dispersion and a capacitor were fabricated in the same manner as in Example 1, except that benzyldodecyldimethylammonium bromide was changed to benzyltrimethylammonium chloride.

[0090] <Example 3> In Example 1, a conductive polymer dispersion and a capacitor were fabricated in the same manner as in Example 1, except that benzyldodecyldimethylammonium bromide was changed to benzyldimethyltetradecylammonium chloride.

[0091] <Example 4> In Example 1, a conductive polymer dispersion and a capacitor were produced in the same manner as in Example 1, except that benzyl dodecyl dimethyl ammonium bromide was changed to lauryl trimethyl ammonium chloride.

[0092] <Example 5> In Example 1, a conductive polymer dispersion and a capacitor were produced in the same manner as in Example 1, except that the blending amount of benzyl dodecyl dimethyl ammonium bromide was increased by 2.7 times in terms of the amount of substance.

[0093] <Comparative Example 1> A PEDOT-PSS aqueous dispersion (solid content concentration: 1.6% by mass) was obtained and a capacitor was produced in the same manner as in Example 1, except that a cationic surfactant was not used.

[0094] [Measurement of Viscosity] The viscosity of the PEDOT-PSS aqueous dispersion with a solid content concentration of 1.6% by mass obtained in each example was measured using a vibrating viscometer (SV-10, manufactured by A&D Company, Limited). The measurement results of the initial viscosity are shown in Table 1. The above viscosity was measured at 23°C in accordance with JIS Z8803:2011 (Method for Measuring Viscosity by Vibration Viscometer) using a tuning fork vibrating viscometer.

[0095] [Measurement of Particle Size] Using the PEDOT-PSS aqueous dispersion with a solid content concentration of 1.6% by mass obtained in each example as a sample (25°C), the average particle diameter d (hydrodynamic diameter) and polydispersity index were determined by the cumulant method from the autocorrelation function obtained by the photon correlation method by the dynamic light scattering method using a zeta potential, particle size, and molecular weight measurement system (ELSZ-2000ZS, manufactured by Otsuka Electronics Co., Ltd.), and the values were taken as the particle size.

[0096] (Production Example 2) Preparation of Capacitor Element After connecting an anode lead terminal to an etched aluminum foil (anode foil), a voltage of 50 V was applied in a 10% by mass aqueous solution of ammonium adipate for formation (oxidation treatment) to form a dielectric layer on both sides of the aluminum foil to obtain an anode foil. Next, an opposing aluminum cathode foil with cathode lead terminals welded to both sides of the anode foil was laminated via a separator made of cellulose, and this was wound into a cylindrical shape to obtain a capacitor element.

[0097] (Production Example 3) Production of Capacitor 85.27 g of the PEDOT-PSS aqueous dispersion obtained in each example, 9.0 g of diethylene glycol, 5.5 g of PEG600, and 0.23 g of imidazole were mixed to obtain a paint for forming a solid electrolyte layer. After immersing the capacitor element in the paint obtained above under reduced pressure, the step of drying for 20 minutes with a hot air dryer at 120°C was performed twice to form a solid electrolyte layer containing a conductive composite on the surface of the dielectric layer. Further, the capacitor element was loaded into an aluminum case and sealed with a sealing rubber to fabricate a capacitor.

[0098] [Measurement of Equivalent Series Resistance] Regarding the capacitors fabricated using the PEDOT-PSS aqueous dispersions of each example, the equivalent series resistance (ESR) (unit: mΩ) at 100 kHz was measured using an LCR meter ZM2345 (manufactured by NF Circuit Design Block). For ESR, after measuring the initial ESR, the capacitor was subjected to a heat treatment of standing in a thermostat at 145°C for 500 hours, and then the ESR was measured again. These measurement results are shown in Table 1.

[0099] [Table 1]

[0100] From the above, the conductive polymer dispersion of the example according to the present invention contains a conductive composite with a small particle size, has a low viscosity, and can form a conductive layer showing good conductivity. For the capacitors fabricated using the conductive polymer dispersion of the example, the initial ESRs were substantially equivalent, and an increase in ESR after heat treatment could be suppressed. [Explanation of Reference Numerals]

[0101] 10 Capacitor 11 Anode 12 Dielectric layer 13 Cathode 14 Solid electrolyte layer

Claims

1. A method for producing a conductive polymer dispersion, comprising: a polymerization step of polymerizing a monomer that forms a π-conjugated conductive polymer in a reaction liquid containing a polyanion, a cationic surfactant, and an aqueous dispersion medium, thereby forming a conductive complex containing the π-conjugated conductive polymer and the polyanion.

2. 2. The method for producing a conductive polymer dispersion according to claim 1, wherein the conductive polymer dispersion comprises a conductive complex containing the π-conjugated conductive polymer and the polyanion, an aqueous dispersion medium, and the cationic surfactant.

3. The method for producing a conductive polymer dispersion liquid according to claim 1 , wherein the cationic surfactant is a tertiary amine, a quaternary ammonium, or a salt thereof.

4. The method for producing a conductive polymer dispersion liquid according to claim 1 , wherein the cationic surfactant has a chemical structure represented by the following formula (1) or (2): 【Chemistry 1】 [In the formula, R １ , R ２ , R ３ , R ４ , R ５ each independently represents an alkyl group having 1 to 20 carbon atoms or a benzyl group, and A represents a halide ion or a hydroxide ion.

5. The method for producing a conductive polymer dispersion liquid according to claim 1 , wherein the cationic surfactant has a chemical structure represented by the following formula (3): 【Chemistry 2】 [In the formula, R ６ represents an alkyl group having 1 to 20 carbon atoms, and A represents a halide ion or a hydroxide ion.

6. 2. The method for producing a conductive polymer dispersion liquid according to claim 1, wherein the cationic surfactant is at least one selected from the group consisting of lauryl trimethyl ammonium, benzyl dimethyl tetradecyl ammonium, benzyl cetyl dimethyl ammonium, benzyl dodecyl dimethyl ammonium, benzyl trimethyl ammonium, and salts thereof.

7. The method for producing a conductive polymer dispersion according to claim 6, 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 partial surface of a substrate, and drying the applied coating to form a conductive layer.

10. A method for manufacturing a capacitor comprising: 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 on the side opposite to the anode; and a solid electrolyte layer formed between the dielectric layer and the cathode, comprising the steps of:

9. A method for producing a capacitor, 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 a surface of the dielectric layer, and drying the applied conductive polymer dispersion to form the solid electrolyte layer.

Images