Conductive composite dispersion, capacitor and method for manufacturing the same, and conductive laminate and method for manufacturing the same

Abstract

This invention provides a conductive composite dispersion suitable for the manufacture of high-performance capacitors. [Solution] In one aspect of the present invention, a conductive composite dispersion is provided, comprising a conductive composite containing a π-conjugated conductive polymer and a polyanion, water, and a nonionic surfactant. The present invention also provides 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 of the dielectric layer opposite to the anode, and a solid electrolyte layer formed between the dielectric layer and the cathode, wherein the solid electrolyte layer is a cured product of the conductive composite dispersion.

Description

[Technical Field]

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

[0002] π-conjugated conductive polymers, whose main chain is composed of π-conjugated groups, form conductive complexes when doped with polyanions containing anionic groups, resulting in dispersibility in water. A method for manufacturing a capacitor is disclosed (for example, Patent Document 1) in which a paint made from a conductive composite dispersion containing a conductive composite is applied to a dielectric layer provided on the anode surface made of valve metal, dried to form a solid electrolyte layer, and a cathode is placed opposite this layer. According to this disclosure, capacitor performance is improved by incorporating certain unsaturated aliphatic alcohol compounds into the paint. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-071400 [Overview of the project] [Problems that the invention aims to solve]

[0004] Capacitors with a solid electrolyte layer are required to have a low equivalent series resistance (ESR).

[0005] This invention provides a conductive composite dispersion that is suitable for the manufacture of high-performance capacitors and has excellent storage stability, as well as a capacitor using the same and a method for manufacturing the same. [Means for solving the problem]

[0006] The present invention includes the following embodiments. [1] A conductive composite dispersion comprising a π-conjugated conductive polymer and a polyanion, water, and a nonionic surfactant. [2] The conductive composite dispersion according to [1], wherein the nonionic surfactant comprises a polyoxyalkylene alkyl ether. [3] The conductive composite dispersion according to [1] or [2], wherein the nonionic surfactant comprises acetylene glycol or a derivative thereof. [4] A conductive composite dispersion according to any one of [1] to [3], further comprising a neutralizing agent. [5] A conductive composite dispersion according to any one of [1] to [4], wherein the π-conjugated conductive polymer comprises poly(3,4-ethylenedioxythiophene). [6] A conductive composite dispersion according to any one of items [1] to [5], wherein the viscosity at a temperature of 23°C is 35.0 mPa·s or less. [7] 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 dielectric layer opposite to the anode, and a solid electrolyte layer formed between the dielectric layer and the cathode, wherein the solid electrolyte layer is a cured product of a conductive composite dispersion according to any one of [1] to [6]. [8] A method for manufacturing a capacitor, comprising the step of applying a conductive composite dispersion according to any one of [1] to [6] to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal, and drying to form a solid electrolyte layer. [9] A conductive laminate comprising a substrate and a conductive layer formed on at least a portion of the surface of the substrate, wherein the conductive layer is a cured product of a conductive composite dispersion according to any one of [1] to [6].

[10] A method for producing a conductive laminate, comprising the step of applying a conductive composite dispersion according to any one of [1] to [6] to the surface of at least a portion of a substrate and drying it to form a conductive layer. [Effects of the Invention]

[0007] Since the conductive composite dispersion of the present invention contains a nonionic surfactant, a solid electrolyte layer excellent in the performance as a conductor can be formed on an anode made of a porous body of valve metal. This property is suitable not only for the production of capacitors but also for the production of a conductive laminate in which a conductive layer is laminated on a substrate. Further, since the conductive composite dispersion of the present invention contains a nonionic surfactant, it also has excellent storage stability and can maintain a low viscosity.

[0008] The present invention is considered to contribute to SDGs Goal 12, "Responsibility for Production and Consumption."

[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] It is a cross-sectional view showing an embodiment of a capacitor.

Modes for Carrying Out the Invention

[0011] ≪Conductive Composite Dispersion≫ The conductive composite dispersion of the first aspect of the present invention contains a conductive composite containing a π-conjugated conductive polymer and a polyanion, water, and a nonionic surfactant.

[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 anion groups dope the π-conjugated conductive polymer, and it has surplus anion groups that do not participate in doping. Since the surplus anion groups are hydrophilic groups, the conductive composite has water dispersibility.

[0013] (π-Conjugated Conductive Polymer) Any organic polymer whose main chain is composed of a π-conjugated system can be used as the π-conjugated conductive polymer. Examples include polypyrrole-based conductive polymers, polythiophene-based conductive polymers, polyacetylene-based conductive polymers, polyphenylene-based conductive polymers, polyphenylene-vinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophene-vinylene-based conductive polymers, and copolymers thereof. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophenes, and polyaniline-based conductive polymers are preferred, and from the viewpoint of transparency, polythiophene-based conductive polymers are more preferred.

[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-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), 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-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), 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 due to its excellent conductivity, transparency, and heat resistance. The conductive composite may contain one type of π-conjugated conductive polymer, or two or more types.

[0015] (Polyanion) A polyanion is a polymer that has two or more monomer units containing anionic groups within its molecule. The anionic groups of this polyanion function as dopants for π-conjugated conductive polymers, thereby improving the conductivity of the π-conjugated conductive polymer. The anionic group of the polyanion is preferably a sulfo group or a carboxyl group. Specific examples of such polyanions include polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylic acid esters having sulfo groups, polymethacrylic acid esters having sulfo groups (for example, poly(4-sulfobutyl methacrylate, polysulfoethyl methacrylate, polymethacryloyloxybenzene sulfonic acid), poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, and other polymers having sulfo groups, as well as polymers having carboxyl groups such as polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacrylic acid, polymethacrylic acid, poly(2-acrylamido-2-methylpropanecarboxylic acid), and polyisoprene carboxylic acid. Polyanions may be homopolymers formed by the polymerization of a single monomer, or copolymers formed by the polymerization of two or more monomers. Among these polyanions, polymers having sulfo groups are preferred because they can achieve higher conductivity, and polystyrene sulfonic acid is even more preferred.

[0016] The weight-average molecular weight Mw of the polyanion is not particularly limited, for example, preferably between 10,000 and 1,000,000, more preferably between 50,000 and 800,000, and even more preferably between 100,000 and 600,000. When the weight-average molecular weight Mw of the polyanion is within the above range, the viscosity of the conductive composite dispersion of this embodiment becomes moderately low, making it possible to easily manufacture capacitors with low ESR. The weight-average molecular weight (Mw) of polyanions is the average molecular weight on a mass basis, calculated using gel filtration chromatography and converted to pullulan equivalent.

[0017] The polyanion content in the conductive composite dispersion of this embodiment is preferably in the range of 1 to 1000 parts by mass, more preferably 10 to 700 parts by mass, and even more preferably 100 to 500 parts by mass, per 100 parts by mass of the π-conjugated conductive polymer. If the polyanion content is above 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 polyanion content is below the upper limit, the π-conjugated conductive polymer can be sufficiently contained, thus ensuring sufficient conductivity.

[0018] In the conductive composite dispersion of this embodiment, the content of the conductive composite is preferably 0.1 parts by mass or more and 3.0 parts by mass or less, more preferably 0.5 parts by mass or more and 2.5 parts by mass or less, even more preferably 1.0 part by mass or more and 2.3 parts by mass or less, and most preferably 1.3 parts by mass or more and 2.0 parts by mass or less, based on 100 parts by mass of the total of the conductive composite (total of π-conjugated conductive polymer and polyanion) and water. If the value is above the lower limit of the above range, the conductivity of the cured product of the conductive composite dispersion will be further increased. If the value is below the upper limit of the above range, the viscosity of the conductive composite dispersion can be reduced, and the dispersibility of the conductive composite can be further improved.

[0019] The content of the conductive composite (total content of π-conjugated conductive polymer and polyanion) relative to the total mass of the conductive composite dispersion in this embodiment 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 2.5% by mass or less, and even more preferably 1.0% by mass or more and 2.0% by mass or less. If the value is above the lower limit of the above range, the conductivity of the cured product of the conductive composite dispersion will be further increased. If the value is below the upper limit of the above range, the viscosity of the conductive composite dispersion can be reduced, and the dispersibility of the conductive composite can be further improved.

[0020] <Nonionic surfactants> Since the conductive composite dispersion of this aspect contains a nonionic surfactant, the capacitor performance can be improved. Although the details of this mechanism are not yet understood, it is presumed that one of the factors is that the nonionic surfactant reduces the viscosity of the conductive composite dispersion.

[0021] A nonionic surfactant is an organic compound that does not have a functional group that ionizes in water and can function as a surfactant by having a hydrophobic site and a hydrophilic site in the molecule. From the viewpoint of enhancing the performance of the capacitor to be manufactured, the nonionic surfactant used in this aspect is preferably polyoxyalkylene alkyl ether, polyoxyalkylene styrenated phenyl ether, or acetylene glycol or its derivative.

[0022] Polyoxyalkylene alkyl ether is preferably a compound represented by the formula: R 1 -O-(R 2 -O) n -H. In the formula, R 1 represents an alkyl group, R 2 represents an alkylene group, and n represents a natural number. R 1 The alkyl group of may be linear or branched, and its carbon number is preferably 1 to 24, more preferably 5 to 20, and even more preferably 8 to 12 from the viewpoint of enhancing the effect as a surfactant. R 2 The carbon number of the alkylene group of is preferably 1 to 12, more preferably 2 to 8, and even more preferably 2 to 4 from the viewpoint of enhancing the effect as a surfactant. n is, for example, 1 to 150, and is appropriately adjusted according to the desired molecular weight. Examples of the molecular weight of polyoxyalkylene alkyl ether include 300 to 1000.

[0023] Polyoxyalkylene styrenated phenyl ether is a compound represented by the formula: Ph-CHCH3-R 3 -O-(R 2 -O) nIt is preferable that the compound is represented by -H. In the formula, Ph represents a phenyl group, and R 3 represents a phenylene group, R 2 represents an alkylene group, and n represents a natural number. R 2 From the viewpoint of enhancing the surfactant effect, the number of carbon atoms in the alkylene group is preferably 1 to 12, more preferably 2 to 8, and even more preferably 2 to 4. n can range from 1 to 150, for example, and is adjusted as appropriate depending on the desired molecular weight. Examples of molecular weights for polyoxyalkylene alkyl ethers include 300 to 1000.

[0024] Acetylene glycol is 2,4,7,9-tetramethyl-5-decine-4,7-diol (abbreviated as TMDD), and has an acetylene bond and a hydroxyl group in the center, with hydrophobic groups on either side. As derivatives of acetylene glycol, examples include derivatives obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to the hydroxyl group in the center of the molecule in order to adjust its hydrophilicity. The number of moles of alkylene oxide added to 1 mole of acetylene glycol can be, for example, 5 to 30 moles.

[0025] The content of the nonionic surfactant in the conductive composite dispersion of this embodiment is preferably 1 to 50 parts by mass, more preferably 3 to 30 parts by mass, and even more preferably 5 to 20 parts by mass, per 100 parts by mass of the conductive composite (total of π-conjugated conductive polymer and polyanion). If the value is above the lower limit of the above range, the effects of incorporating nonionic surfactants will be fully realized, resulting in improved capacitor performance. If the value is below the upper limit of the above range, the relative content of the conductive composite becomes sufficient, and as a result of the conductivity being fully expressed, the performance of the capacitor can be further improved.

[0026] The content of the nonionic surfactant relative to the total mass of the conductive composite dispersion in this embodiment can be, for example, 0.01% by mass or more and 1.0% by mass or less, preferably 0.05% by mass or more and 0.5% by mass or less. Within the above range, it is possible to suppress the increase in viscosity of the conductive composite dispersion and improve the dispersibility of the conductive composite.

[0027] <Dispersion medium> The dispersion medium contained in the conductive composite dispersion is preferably an aqueous dispersion medium containing water, given that the conductive composite is hydrophilic. However, it may also 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. Conductive composites have excess anionic groups derived from polyanions and exhibit high dispersibility in water; therefore, water-soluble organic solvents are preferred as dispersion media other than water. Here, water-soluble organic solvents are organic solvents whose solubility in 100g of water at 20°C is 1g or more, and examples include alcohol-based solvents, ketone-based solvents, and ester-based solvents. The dispersion media may consist of one or more water-soluble organic solvents. Non-water-soluble organic solvents are organic solvents whose solubility is less than 1g.

[0028] From the viewpoint of improving the dispersibility of the conductive composite, the water content relative to the total mass of the conductive composite dispersion in this embodiment is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. When water is added above the lower limit mentioned above, the dispersibility of the conductive composite is further enhanced, and the performance of a capacitor having a solid electrolyte layer formed from the conductive composite dispersion can be further improved. In addition, the conductivity of the conductive layer formed from the conductive composite dispersion can be further enhanced.

[0029] <Neutralizing agent> The conductive composite dispersion of this embodiment may further contain one or more neutralizing agents. When the polyanion has an acidic group, the conductive composite dispersion tends to become strongly acidic, but this can be neutralized by a neutralizing agent. Examples of neutralizing agents include basic compounds. Basic compounds function as Brønsted bases, accepting protons from the excess anionic groups of polyanions. To perform this function, the solubility of the basic compound in water is preferably 0.001 g or more per 100 g of water at 20°C. While there is no particular upper limit to the solubility, even a solubility of around 0.1 g is sufficient to perform the above function.

[0030] Examples of basic compounds that can be used include nitrogen-containing organic or inorganic basic compounds, alkali metal or group 2 metal hydroxides, and various carbonates and bicarbonates. Specific examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide. Specific examples of carbonates or bicarbonates include ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, and sodium carbonate. Specific examples of quaternary ammonium hydroxides or their salts include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide.

[0031] The conductive composite dispersion of this embodiment preferably contains at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine as the basic compound.

[0032] Examples of nitrogen-containing aromatic cyclic compounds (aromatic compounds in which at least one nitrogen atom forms a ring structure) 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, and 1-cyanoethyl-2-ethyl-4-methyl Examples of derivatives include imidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-acetylimidazole, 2-aminobenzimidazole, 2-amino-1-methylbenzimidazole, 2-hydroxybenzimidazole, 2-(2-pyridyl)benzimidazole, pyridine, pyrimidine, pyrazine, and their alkyl-substituted derivatives (e.g., derivatives with C1-C4 alkyl groups such as methyl, ethyl, propyl, and butyl), halogen-substituted derivatives (e.g., derivatives with halogen groups such as fluoro, chloro, and brom), and nitrile-substituted derivatives. Among these, imidazole is preferred. From the perspective of reducing the ESR of the capacitors being manufactured, nitrogen-containing aromatic cyclic compounds preferable.

[0033] Examples of tertiary amines include triethanolamine, trimethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, trioctylamine, triphenylamine, trynzylamine, and trinaphthylamine.

[0034] The content of basic compounds in the conductive composite dispersion is preferably, for example, 1 to 100 parts by mass, more preferably 10 to 70 parts by mass, and even more preferably 20 to 40 parts by mass, per 100 parts by mass of the conductive composite (total of π-conjugated conductive polymer and polyanion). Within the above preferred range, the acidity of the conductive composite dispersion is reduced, the corrosiveness to the substrate is decreased, and the performance of the capacitor can be further improved.

[0035] The amount of basic compound contained in the conductive composite dispersion is preferably such that the pH of the conductive composite dispersion (at 25°C) is between 2.0 and less than 7.0. Within the above preferred range, the acidity of the conductive composite dispersion is reduced, the corrosiveness to the substrate is decreased, and the performance of the capacitor can be further improved.

[0036] <Optional additives> The conductive composite dispersion may contain other optional additives. The proportion of these additives can be appropriately determined depending on the type of additive, but for example, it can be 1 to 1000 parts by mass per 100 parts by mass of the total of the π-conjugated conductive polymer and polyanion. Here, the optional additives are compounds other than the basic compound, the nonionic surfactant, and the dispersion medium.

[0037] Optional additives include, for example, surfactants, inorganic conductive agents, defoamers, coupling agents, antioxidants, and UV absorbers. Examples of surfactants include anionic and cationic surfactants. Polymeric surfactants such as polyvinyl alcohol may also be added. Examples of inorganic conductive agents include metal ions and conductive carbon. Metal ions can be generated by dissolving metal salts in water. Examples of defoaming agents include silicone resins, polydimethylsiloxanes, and silicone oils. Examples of coupling agents include silane coupling agents having vinyl groups, amino groups, epoxy groups, etc. Examples of antioxidants include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, and sugars. Examples of UV absorbers include benzotriazole-based UV absorbers, benzophenone-based UV absorbers, salicylate-based UV absorbers, cyanoacrylate-based UV absorbers, oxanilide-based UV absorbers, hindered amine-based UV absorbers, and benzoate-based UV absorbers.

[0038] The viscosity (in units: mPa·s) of the conductive composite dispersion of this embodiment at 23°C is preferably 10.0 to 35.0, preferably 12.0 to 34.0, more preferably 15.0 to 33.0, and even more preferably 20.0 to 32.0. If the value is above the lower limit mentioned above, it becomes easier to apply and adhere to a substrate such as a dielectric layer, and a thick solid electrolyte layer can be easily formed. When the value is below the upper limit mentioned above, it becomes easier for the material to penetrate the fine porous structure of the dielectric layer, allowing for the easy formation of a high-performance solid electrolyte layer. The viscosity measurements described above were taken at 23°C using a tuning fork vibrating viscometer, in accordance with JIS Z8803:2011 (Viscosity measurement method using vibrating viscometer).

[0039] ≪Method for producing conductive composite dispersion≫ A method for producing a conductive composite dispersion according to the first aspect of the present invention includes, for example, adding a nonionic surfactant and, if necessary, a neutralizing agent to an aqueous dispersion of the conductive composite. The composition of each component can be desired, and it is preferable to combine them within the preferred range described above. The aqueous dispersion of the conductive composite may be obtained by chemical oxidation polymerization of monomers that form a π-conjugated conductive polymer in an aqueous solution of polyanions using a known method, or a commercially available one may be used. To improve the dispersibility of the conductive composite in the conductive composite dispersion, a high-pressure dispersion treatment using a high-pressure homogenizer with shear force may be performed.

[0040] Capacitor manufacturing method A second aspect of the present invention is a method for manufacturing a capacitor, comprising the step of applying a conductive composite dispersion of the first aspect to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal, and drying it to form a solid electrolyte layer.

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

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

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

[0044] [Film forming process] In this step, the aforementioned conductive composite dispersion is applied to at least a portion of the surface of the dielectric layer 12 and dried to form a solid electrolyte layer 14.

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

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

[0047] The composition of the components contained in the solid electrolyte layer 14 reflects the composition of the coated conductive composite dispersion. The content of the nonionic surfactant per 100 parts by mass of the conductive composite (total of π-conjugated conductive polymer and polyanion) contained in the solid electrolyte layer 14 is preferably, for example, 1 part by mass or more and 50 parts by mass or less, more preferably 3 parts by mass or more and 30 parts by mass or less, and even more preferably 5 parts by mass or more and 20 parts by mass or less. If the value is above the lower limit of the above range, the effects of containing nonionic surfactants will be fully realized, resulting in improved capacitor performance. If the value is below the upper limit of the above range, the relative content of the conductive composite becomes sufficient, and as a result of the conductivity being fully expressed, the performance of the capacitor can be further improved.

[0048] Capacitor A third aspect of the present invention is 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 dielectric layer opposite to 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 composite dispersion of the first aspect. As an example, the capacitor of this aspect can be manufactured by the manufacturing method of the second aspect.

[0049] An example of an embodiment of the capacitor described above will be explained with reference to Figure 1. The capacitor 10 shown in Figure 1 comprises 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 the dielectric layer 12, and a cathode 13 provided on the outermost side. The cathode 13 is provided on the opposite side from the anode 11, with the dielectric layer 12 and the solid electrolyte layer 14 in between.

[0050] Examples of valve metals that constitute 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 anode 11 include aluminum foil that has been etched to increase its surface area and then oxidized, or sintered tantalum or niobium particles whose surface has been oxidized and formed into pellets. Materials processed in this way become porous bodies with irregularities formed on their surface.

[0051] In this embodiment, the dielectric layer 12 is a layer formed by oxidation of the surface of the anode 11. For example, it is formed by anodizing the surface of the metal anode 11 in an electrolyte such as an aqueous solution of ammonium adipate. Similar to the anode 11, the dielectric layer 12 also has irregularities formed on it.

[0052] In this embodiment, the cathode 13 can be a conductive layer formed from a conductive paste or a metal layer made of a conductive material such as aluminum foil.

[0053] In this embodiment, the solid electrolyte layer 14 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 be constant or not; for example, a thickness of 1 μm or more and 100 μm or less is possible.

[0054] [Electrolyte] The capacitor may have an electrolyte that impregnates a solid electrolyte layer. Examples of solvents that constitute the electrolyte 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. The electrolytes constituting the electrolyte solution include, for example, 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, organic acids such as azelaic acid and sebacic acid; or boric acid, polyhydric alcohol complex compounds of boric acid obtained from boric acid and polyhydric alcohols; and inorganic acids such as phosphoric acid, carbonic acid, and silicic acid as anionic components, with primary amines (methylamine, ethylamine, propylamine, Examples include electrolytes with cationic components such as butylamine, ethylenediamine, secondary amines (dimethylamine, diethylamine, dipropylamine, methylethylamine, diphenylamine, etc.), tertiary amines (trimethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo(5,4,0)-undecene-7, etc.), and tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, etc.).

[0055] The capacitor is not limited to the configuration described above; a separator may be provided between the dielectric layer and the cathode. An example of a capacitor with a separator between the dielectric layer and the cathode is a wound-type capacitor. Examples of separators include sheets (including nonwoven fabrics) made of cellulose, polyvinyl alcohol, polyester, polyethylene, polystyrene, polypropylene, polyimide, polyamide, polyvinylidene fluoride, etc., and glass fiber nonwoven fabrics. The density of the separator is, for example, 0.1 g / cm³. 3 More than 1.0g / cm 3 The following are listed: When a separator is provided, a method can be applied in which carbon paste or silver paste is impregnated into the separator to form the cathode.

[0056] ≪Method for manufacturing conductive laminates≫ A fourth aspect of the present invention is a method for producing a conductive laminate by a manufacturing method that includes the step of coating a conductive composite dispersion of the first aspect of the present invention onto at least a portion of the surface of a substrate to form a conductive layer.

[0057] Methods for coating (applying) the conductive composite dispersion to any surface of a substrate include, for example, methods using coaters such as gravure coaters, roll coaters, curtain flow coaters, spin coaters, bar coaters, reverse coaters, kiss coaters, fountain coaters, rod coaters, air doctor coaters, knife coaters, blade coaters, cast coaters, and screen coaters; methods using sprayers such as air sprayers, airless sprayers, and rotor dampening devices; and immersion methods such as dipping.

[0058] The amount of conductive composite dispersion applied to the substrate is not particularly limited, but for example, 0.01 to 10.0 g / m² of non-volatile components is recommended. 2 A range of [specified range] is preferred.

[0059] A conductive layer can be formed by drying a coating film made of a conductive composite dispersion applied to a substrate, thereby removing at least a portion of the dispersion medium and allowing it to harden. Methods for drying the coating include heat drying and vacuum drying. For heat drying, for example, methods such as hot air heating and infrared heating can be used. When applying heat drying, the heating temperature is set appropriately according to the dispersion medium used, but is usually within the range of 50°C to 200°C. Here, the heating temperature is the set temperature of the drying apparatus. Within the above heating temperature range, a suitable drying time is preferably 0.5 minutes to 30 minutes, and more preferably 1 minute to 15 minutes.

[0060] <<Conductive Laminate>> A fifth aspect of the present invention is a conductive laminate comprising a substrate and a conductive layer formed on at least a portion of the surface of the substrate, wherein the conductive layer contains a cured product of the conductive composite dispersion of the first aspect. As an example, the conductive laminate of this aspect can be manufactured by the manufacturing method of the fourth aspect.

[0061] [Conductive layer] The area in which the conductive layer is formed may be the entire surface of any surface of the substrate, or it may be only a part of it. In the case of a conductive film, it is preferable that a conductive layer of substantially uniform thickness is formed on substantially the entire surface of one or the other surface of the film substrate. If the conductive layer is formed on only 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 area with the conductive layer and the area without the conductive layer may exist on the same surface and be roughly separated.

[0062] The average thickness of the conductive layer is preferably, for example, 10 nm to 100 μm, more preferably 20 nm to 50 μm, and even more preferably 30 nm to 30 μm. If the average thickness of the conductive layer is above the lower limit, high conductivity can be achieved, and if it is below the upper limit, the adhesion of the conductive layer to the substrate is further improved.

[0063] The composition of the components contained in the conductive layer reflects the composition of the coated conductive composite dispersion. The content of the nonionic surfactant per 100 parts by mass of the conductive composite (total of π-conjugated conductive polymer and polyanions) contained in the conductive layer is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 3 parts by mass or more and 30 parts by mass or less, and even more preferably 5 parts by mass or more and 20 parts by mass or less. Within the above range, the conductivity of the conductive layer is good.

[0064] [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 include mainly flat shapes such as films and substrates. Examples of insulating materials include glass, synthetic resins, and ceramics. Examples of conductive materials include metals, conductive metal oxides, and carbon.

[0065] (Film substrate) When a film substrate is used as the aforementioned substrate, the conductive laminate becomes a conductive film. Examples of the film substrate include plastic films made of synthetic resins. Examples of the synthetic resins 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 elastomer, polyester elastomer, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyimide, cellulose triacetate, and cellulose acetate propionate. From the viewpoint of improving 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.

[0066] The synthetic resin used for the film substrate may be amorphous or crystalline. The film substrate may be unstretched or stretched. The film substrate may be subjected to surface treatments such as corona discharge treatment, plasma treatment, or flame treatment in order to further improve the adhesion of the conductive layer.

[0067] The average thickness of the film substrate is preferably 5 μm to 500 μm, and more preferably 20 μm to 200 μm. If the average thickness of the film substrate is above the lower limit, it becomes less prone to tearing, and if it is below the upper limit, sufficient flexibility as a film can be ensured. The average thickness of the film substrate is the average of the measurements taken at 10 randomly selected locations.

[0068] (Glass substrate) Examples of glass substrates include alkali-free glass substrates, soda-lime glass substrates, borosilicate glass substrates, and quartz glass substrates. Since the presence of alkaline components in the substrate tends to reduce the conductivity of the conductive layer, alkali-free glass is preferred among the glass substrates. Here, alkali-free glass refers to a glass composition in which the content of alkaline components is 0.1% by mass or less of the total mass of the glass composition.

[0069] The average thickness of the glass substrate is preferably 100 μm to 3000 μm, and more preferably 100 μm to 1000 μm. If the average thickness of the glass substrate is above the lower limit, it becomes less prone to breakage, and if it is below the upper limit, it contributes to thinning the conductive laminate. The average thickness of the glass substrate is the average of the measurements taken at 10 randomly selected locations. [Examples]

[0070] (Manufacturing Example 1) Production of polystyrene sulfonic acid 206 g of sodium styrene sulfonate was dissolved in 1000 ml of deionized water, and while stirring at 80°C, 1.14 g of ammonium persulfate oxidizing agent solution, which had been previously dissolved in 10 ml of water, was added dropwise for 20 minutes, and this solution was stirred for 12 hours. To the obtained sodium polystyrene sulfonate solution, 1000 ml of sulfuric acid diluted to 10% by mass was added, and approximately 1000 ml of the solvent from the resulting polystyrene sulfonate solution was removed by ultrafiltration. Next, 2000 ml of deionized water was added to the remaining solution, and approximately 2000 ml of solvent was removed by ultrafiltration to wash the polystyrene sulfonate with water. This washing procedure was repeated three times. The water in the resulting solution was removed under reduced pressure to obtain colorless, solid polystyrene sulfonic acid (PSS).

[0071] (Manufacturing Example 2) Production of PEDOT-PSS aqueous dispersion A solution of 14.2 g of 3,4-ethylenedioxythiophene and 36.7 g of polystyrene sulfonic acid dissolved in 2000 ml of deionized water was mixed at 20°C. The resulting mixed solution was kept at 20°C, and while stirring, a solution of 29.64 g of ammonium persulfate and 8.0 g of ferric sulfate, dissolved in 200 ml of deionized water, was slowly added as an oxidation catalyst, and the mixture was stirred for 3 hours to allow the reaction to proceed. 2000 ml of deionized water was added to the resulting reaction mixture, and approximately 2000 ml of solvent was removed by ultrafiltration. This procedure was repeated three times. Then, 200 ml of sulfuric acid diluted to 10% by mass and 2000 ml of deionized water were added to the obtained solution, and approximately 2000 ml of solvent was removed by ultrafiltration. 2000 ml of deionized water was added to the remaining solution, and approximately 2000 ml of solution was removed by ultrafiltration. This procedure was repeated three times. Furthermore, 2000 ml of deionized water was added to the obtained solution, and approximately 2000 ml of solvent was removed by ultrafiltration. This procedure was repeated five times to obtain a 1.2% by mass polystyrene sulfonic acid-doped poly(3,4-ethylenedioxythiophene) solution (PEDOT-PSS aqueous dispersion). The solution was then concentrated to 1.7% by mass by further ultrafiltration, and treated at 160 MPa using a high-pressure homogenizer to obtain a PEDOT-PSS aqueous dispersion.

[0072] (Manufacturing Example 3) Creation of capacitor elements After connecting anode lead terminals to etched aluminum foil (anodic foil), a voltage of 40V was applied in a 10% by mass aqueous solution of ammonium adipate to perform a chemical conversion (oxidation treatment) to form dielectric layers on both sides of the aluminum foil and obtain the anode foil. Next, opposing aluminum cathode foils, each with cathode lead terminals welded to both sides of an anode foil, were laminated with a cellulose separator in between, and this was wound into a cylindrical shape to obtain a capacitor element.

[0073] The following materials were used in the following tests. • Neugen SD-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., nonionic surfactant, polyoxyethylene isodecyl ether) • Neugen SD-60 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., nonionic surfactant, polyoxyethylene isodecyl ether, average molecular weight: approximately 450) • Neugen SD-70 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., nonionic surfactant, polyoxyethylene isodecyl ether) • Neugen SD-80 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., nonionic surfactant, polyoxyethylene isodecyl ether) • Neugen EA-087 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., nonionic surfactant, polyoxyethylene styrene-phenyl ether) • Neugen EA-177 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., nonionic surfactant, polyoxyethylene styrene-phenyl ether) • Neugen XL-41 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., nonionic surfactant, polyoxyalkylene decyl ether, average molecular weight: approximately 300) • Neugen XL-70 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., nonionic surfactant, polyoxyalkylene decyl ether, average molecular weight: approximately 500) • Neugen XL-60X (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., nonionic surfactant, polyoxyalkylene alkyl ether, average molecular weight: approximately 400) • Olphine EXP4001 (manufactured by Nisshin Chemical Industry Co., Ltd., nonionic surfactant, acetylene-based surfactant, self-emulsifying type, mixture of acetylene glycol-ethylene oxide adduct and other surfactants)

[0074] (Example 1) To 100 g of the PEDOT-PSS aqueous dispersion obtained in Production Example 2, 0.44 g of imidazole (25.9 parts by mass per 100 parts by mass of conductive composite) and 0.2 g of Neugen SD-30 (11.8 parts by mass per 100 parts by mass of conductive composite) were added to 100 g of the PEDOT-PSS aqueous dispersion and stirred for 30 minutes to obtain a paint composition (conductive composite dispersion). The pH of the paint composition was 2.6. Next, the capacitor element obtained in Manufacturing Example 3 was immersed in the paint composition under reduced pressure, and then dried in a hot air dryer at 160°C for 30 minutes to obtain a capacitor element in which a solid electrolyte layer containing a conductive composite was formed on the surface of the dielectric layer. Finally, the capacitor element with the solid electrolyte layer described above was placed in an aluminum case and sealed with a rubber seal to create the capacitor.

[0075] (Example 2) The capacitor was fabricated in the same manner as in Example 1, except that the Neugen SD-30 was replaced with a Neugen SD-60.

[0076] (Example 3) A capacitor was fabricated in the same manner as in Example 1, except that Neugen SD-30 was replaced with Neugen SD-60 and the amount of Neugen SD-60 added was changed to 0.1g.

[0077] (Example 4) The capacitor was fabricated in the same manner as in Example 1, except that the Neugen SD-30 was replaced with a Neugen SD-70.

[0078] (Example 5) The capacitor was fabricated in the same manner as in Example 1, except that the Neugen SD-30 was replaced with a Neugen SD-80.

[0079] (Example 6) The capacitor was fabricated in the same manner as in Example 1, except that the Neugen SD-30 was replaced with a Neugen EA-087.

[0080] (Example 7) The capacitor was fabricated in the same manner as in Example 1, except that the Neugen SD-30 was replaced with a Neugen EA-177.

[0081] (Example 8) The capacitor was fabricated in the same manner as in Example 1, except that the Neugen SD-30 was replaced with a Neugen XL-41.

[0082] (Example 9) The capacitor was fabricated in the same manner as in Example 1, except that the Neugen SD-30 was replaced with a Neugen XL-70.

[0083] (Example 10) The capacitor was fabricated in the same manner as in Example 1, except that the Neugen SD-30 was replaced with a Neugen XL-60X.

[0084] (Example 11) The capacitor was fabricated in the same manner as in Example 1, except that the Neugen SD-30 was replaced with an Orfin EXP4001.

[0085] (Comparative Example 1) A capacitor was fabricated in the same manner as in Example 1, except that a nonionic surfactant was not added.

[0086] [Measuring pH] The pH was measured at 25°C using a commercially available pH meter and a standard method.

[0087] [Capacitance and equivalent series resistance] For each example, the equivalent series resistance at 100kHz was measured using an LCR meter ZM2376 (manufactured by NF Circuit Design Block Co., Ltd.).

[0088] [viscosity] The viscosity of each of the above paint compositions immediately after manufacturing was measured at 23°C using a tuning fork vibrating viscometer in accordance with JIS Z8803:2011 (Viscosity measurement method using vibrating viscometer). These measured values ​​are shown in Table 1 as "initial viscosity".

[0089] Next, the paint compositions obtained in each example were placed in sealed bottles and stored in a constant temperature bath at 5°C to 10°C for two weeks, and their viscosity was measured in the same manner as described above. The measurement results are shown in Table 1 as "viscosity after two weeks". The change (increase) from the initial viscosity to the viscosity after two weeks is also shown in Table 1.

[0090] [Table 1]

[0091] From the above, the conductive composite dispersion produced in the embodiment of the present invention contains a nonionic interface, resulting in superior performance of the manufactured capacitor. This is thought to be due to the lower viscosity of the conductive composite dispersion, which allows it to penetrate the anode foil more easily. Furthermore, the change in viscosity of the conductive composite dispersion before and after storage was significantly lower than that of the comparative example, indicating excellent storage stability. [Explanation of symbols]

[0092] 10 Capacitors 11 Anode 12 Dielectric layer 13 Cathode 14 Solid electrolyte layer

Claims

1. A conductive composite dispersion comprising a π-conjugated conductive polymer and a polyanion, water, and a nonionic surfactant.

2. The conductive composite dispersion according to claim 1, wherein the nonionic surfactant comprises a polyoxyalkylene alkyl ether.

3. The conductive composite dispersion according to claim 1, wherein the nonionic surfactant comprises acetylene glycol or a derivative thereof.

4. The conductive composite dispersion according to claim 1, further comprising a neutralizing agent.

5. The conductive composite dispersion according to claim 1, wherein the π-conjugated conductive polymer contains poly(3,4-ethylenedioxythiophene).

6. The conductive composite dispersion according to claim 5, wherein the viscosity at a temperature of 23°C is 35.0 mPa·s or less.

7. The device comprises an anode made of a porous 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 to the anode, and a solid electrolyte layer formed between the dielectric layer and the cathode. A capacitor wherein the solid electrolyte layer is a cured product of a conductive composite dispersion according to any one of claims 1 to 6.

8. A method for manufacturing a capacitor, comprising the step of applying a conductive composite dispersion according to any one of claims 1 to 6 to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal, and drying it to form a solid electrolyte layer.

9. The system comprises a base material and a conductive layer formed on at least a portion of the surface of the base material, A conductive laminate wherein the conductive layer is a cured product of a conductive composite dispersion according to any one of claims 1 to 6.

10. A method for producing a conductive laminate, comprising the steps of applying a conductive composite dispersion according to any one of claims 1 to 6 to at least a portion of the surface of a substrate, and drying it to form a conductive layer.

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