Conductive polymer dispersion, capacitor and method for producing same

Abstract

To provide a capacitor and its manufacturing method with capacitance equivalent to conventional capacitors and reduced equivalent series resistance to conventional capacitors and conductive polymer dispersion liquid used for the manufacturing method.SOLUTION: A capacitor 10 includes: an anode 11 made of a porous body of valve metal; a dielectric layer 12 made of an oxide of the valve metal; a cathode 13 made of conductive material provided on the dielectric layer opposite to the anode; and at least one solid electrolyte layer 14 formed between the dielectric layer and the cathode. The solid electrolyte layer has a conductive composite containing a π-conjugated conductive polymer and a polyanion, a compound represented by a specific chemical formula, and at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a capacitor having a solid electrolyte layer containing a π-conjugated conductive polymer, and a method for producing the same. [Background technology]

[0002] A capacitor is known in which a solid electrolyte layer formed from a conductive polymer dispersion liquid containing poly(3,4-ethylenedioxythiophene) and polystyrenesulfonic acid is disposed between a dielectric layer and a cathode (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-87615 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional capacitors manufactured using conductive polymer dispersions are required to have an increased capacitance and a reduced equivalent series resistance. The present invention provides a capacitor having a capacitance equivalent to that of a conventional capacitor and a reduced equivalent series resistance, a method for producing the same, and a conductive polymer dispersion liquid suitable for the production method. [Means for solving the problem]

[0005] [1] A conductive polymer dispersion liquid containing a conductive complex including a π-conjugated conductive polymer and a polyanion, at least one of compounds represented by the following formula (1) or (2), at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine, and a dispersion medium. [2] The conductive polymer dispersion according to [1], which contains the nitrogen-containing aromatic cyclic compound, and the nitrogen-containing aromatic cyclic compound has a vinyl group, an allyl group, an acryl group or a methacryl group. [3] The conductive polymer dispersion according to [1] or [2], which contains the tertiary amine, and the tertiary amine has a vinyl group, an allyl group, an acrylic group or a methacrylic group. [4] The conductive polymer dispersion according to any one of [1] to [3], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene) or the polyanion is polystyrenesulfonic acid. [5] 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 opposite the anode; and a solid electrolyte layer formed between the dielectric layer and the cathode, wherein the solid electrolyte layer contains a conductive complex including a π-conjugated conductive polymer and a polyanion; at least one compound represented by the following formula (1) or the following formula (2); or a reaction product in which terminal functional groups of one or more compounds represented by the following formula (1) are polymerized with each other; or a reaction product in which terminal functional groups of one or more compounds represented by the following formula (2) are polymerized with each other; and at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine. [6] The capacitor according to [5], wherein the solid electrolyte layer contains a reaction product in which terminal functional groups of one or more compounds represented by formula (1) are polymerized with each other, or a reaction product in which terminal functional groups of one or more compounds represented by formula (2) are polymerized with each other. [7] The capacitor according to [5] or [6], wherein the solid electrolyte layer contains the nitrogen-containing aromatic cyclic compound, the nitrogen-containing aromatic cyclic compound having a vinyl group, an allyl group, an acrylic group or a methacrylic group, and at least a portion of the nitrogen-containing aromatic cyclic compound is bonded to at least a portion of the compound represented by formula (1) or (2) via the functional group. [8] The capacitor according to any one of [5] to [7], wherein the solid electrolyte layer contains the tertiary amine, the tertiary amine having a vinyl group, an allyl group, an acrylic group or a methacrylic group, and at least a portion of the tertiary amine is bonded to at least a portion of the compound represented by formula (1) or (2) via the functional group. [9] The capacitor according to any one of [5] to [8], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene) or the polyanion is polystyrenesulfonic acid.

[10] A method for producing a capacitor, comprising the steps of applying the conductive polymer dispersion liquid according to any one of [1] to [4] to a surface of a dielectric layer formed on a surface of an anode made of a porous valve metal, and drying the applied conductive polymer dispersion liquid to form a solid electrolyte layer. Effect of the Invention

[0006] The capacitor of the present invention has a capacitance equivalent to that of a conventional capacitor and a reduced equivalent series resistance by containing a compound represented by a specific formula and a nitrogen-containing aromatic cyclic compound in a solid electrolyte layer. According to the method for producing a capacitor of the present invention, the capacitor can be easily produced by using the conductive polymer dispersion of the present invention.

[0007] This invention is believed to contribute to SDGs Goal 12, "Responsible Consumption and Production."

[0008] In this specification and claims, the lower limit and upper limit of a numerical range indicated with "to" are included in the numerical range. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an embodiment of a capacitor of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Capacitor The first aspect of the present invention is a capacitor. Examples of its embodiments will be described with reference to the drawings. 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.

[0011] Examples of the valve metal constituting the anode 11 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, antimony, etc. 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 treated in this way become a porous body with irregularities formed on the surface.

[0012] The dielectric layer 12 in the present embodiment is a layer formed by oxidizing the surface of the anode 11. For example, it is formed 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, irregularities are also formed on the dielectric layer 12 (see FIG. 1).

[0013] 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.

[0014] 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. For example, a thickness of 1 μm or more and 100 μm or less can be mentioned.

[0015] <Additive compound> The solid electrolyte layer contains at least one of compounds represented by the following formula (1) or (2). Hereinafter, the compound represented by formula (1) may be referred to as compound (1), and the compound represented by formula (2) may be referred to as compound (2).

[0016] [ka] [In formula (1), R 1 , R 2 Each independently represents a hydrogen atom or an arbitrary substituent, and n represents an integer. 1 , R 2 , R 3 each independently represents a hydrogen atom or an arbitrary substituent, and l, m, and n each represent an integer, and l+m+n=9 to 20.

[0017] R in Equation (1) 1 and R 2 is preferably a hydrogen atom or a methyl group. In the formula (1), n ​​is preferably 0 to 100, more preferably 1 to 30, further preferably 1 to 20, particularly preferably 2 to 10, and most preferably 3 to 7. According to the above preferred embodiment, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor. The solid electrolyte layer may contain one type of compound (1), or two or more types of compounds.

[0018] R in Equation (2) 1 , R 2 and R 3 is preferably a hydrogen atom or a methyl group. In formula (2), l, m, and n each independently represent preferably 0 to 18, more preferably 2 to 10, and further preferably 3 to 7. The sum of l+m+n in formula (2) is 9 to 20, preferably 9 to 18, more preferably 9 to 15, and even more preferably 9 to 12. According to the above preferred embodiment, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor. The compound (2) contained in the solid electrolyte layer may be one type or two or more types.

[0019] The total content of compound (1) and compound (2) contained in the solid electrolyte layer is preferably 10 parts by mass or more and 5,000 parts by mass or less, more preferably 100 parts by mass or more and 1,000 parts by mass or less, still more preferably 200 parts by mass or more and 800 parts by mass or less, and most preferably 300 parts by mass or more and 600 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0020] At least a part of the compounds (1) or (2) contained in the solid electrolyte is preferably bonded to each other by a polymerization reaction via the polymerizable groups at both ends of the molecule. Here, the compounds (1) may be bonded to each other, the compounds (2) may be bonded to each other, or the compounds (1) and (2) may be bonded to each other. These bonds improve the adhesion of the solid electrolyte layer to the dielectric layer, improve the physical strength of the solid electrolyte layer, and improve the durability of the solid electrolyte layer against external stress.

[0021] <Nitrogen-containing compounds> The solid electrolyte layer contains at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine. When the solid electrolyte layer contains a nitrogen-containing aromatic cyclic compound, the nitrogen-containing aromatic cyclic compound may be one type or two or more types. When the solid electrolyte layer contains a tertiary amine, the tertiary amine may be one type or two or more types.

[0022] In the present invention, nitrogen-containing aromatic cyclic compounds (aromatic compounds in which at least one nitrogen atom forms a ring structure) can be roughly classified according to whether or not they have a vinyl-based polymerizable group. Here, the vinyl-based polymerizable group means a polymerizable group having a vinyl group, and examples thereof include a vinyl group, an allyl group (aryl group), an acryl group, and a methacryl group.

[0023] Examples of nitrogen-containing aromatic cyclic compounds not having a vinyl-based polymerizable group include pyrrole, 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, and pyridine.

[0024] When the solid electrolyte layer contains one or more nitrogen-containing aromatic cyclic compounds having no vinyl-based polymerizable group, the total content thereof is preferably 5 parts 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 even more preferably 15 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and the polyanion (i.e., 100 parts by mass of the conductive composite). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0025] Examples of nitrogen-containing aromatic cyclic compounds having a vinyl polymerizable group include 1-vinylimidazole, 2-methyl-1-vinylimidazole, 1-methyl-3-[3-(acryloyloxy)propyl]-1H-imidazol-3-ium, 1-allylimidazole, 2-vinylpyridine, 3-vinylpyridine, and 4-vinylpyridine.

[0026] When the solid electrolyte layer contains one or more nitrogen-containing aromatic cyclic compounds having a vinyl-based polymerizable group, the total content thereof is preferably 8 parts by mass or more and 100 parts by mass or less, more preferably 14 parts by mass or more and 70 parts by mass or less, and even more preferably 20 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and the polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0027] In the present invention, tertiary amines can be broadly classified according to whether they have a vinyl-based polymerizable group or not. Here, the vinyl-based polymerizable group means a polymerizable group having a vinyl group, and examples thereof include a vinyl group, an allyl group (aryl group), an acryl group, and a methacryl group.

[0028] Examples of tertiary amines having no vinyl-based polymerizable group include triethanolamine, trimethylamine, triethylamine, tripropylamine, tributylamine, trioctylamine, triphenylamine, tribenzylamine, and trinaphthylamine.

[0029] When the solid electrolyte layer contains one or more tertiary amines having no vinyl-based polymerizable group, the total content thereof is preferably 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 70 parts by mass or less, and even more preferably 25 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and the polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0030] Examples of tertiary amines having a vinyl-based polymerizable group include dimethylaminopropylacrylamide (abbreviation: DMAPAA), 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 2-(diethylamino)ethyl methacrylate, triallylamine, N-allyldimethylamine, and N-allyldiethylamine.

[0031] When the solid electrolyte layer contains one or more types of tertiary amines having a vinyl-based polymerizable group, the total content thereof is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 20 parts by mass or more and 100 parts by mass or less, and even more preferably 30 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and the polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0032] The nitrogen-containing compound contained in the solid electrolyte layer preferably has the vinyl-based polymerizable group. In this case, at least a part of the nitrogen-containing compounds contained in the solid electrolyte layer is preferably bonded to each other by a polymerization reaction via the vinyl-based polymerizable group. Also, at least a part of the nitrogen-containing compound may be bonded to at least a part of compound (1) or at least a part of compound (2) by a polymerization reaction via the vinyl-based polymerizable group. These bonds improve the adhesion of the solid electrolyte layer to the dielectric layer, improve the physical strength of the solid electrolyte layer, and improve the durability of the solid electrolyte layer against external stress.

[0033] <Conductive composite> Next, the conductive complex contained in the solid electrolyte layer will be described. The conductive complex of this embodiment contains a π-conjugated conductive polymer and a polyanion. The polyanion in the conductive complex is doped into the π-conjugated conductive polymer to form a conductive complex having electrical conductivity. In the polyanion, only a part of the anionic groups is doped into the π-conjugated conductive polymer, and there are excess anionic groups that are not involved in the doping. Since the excess anionic groups are hydrophilic groups, the conductive composite has water dispersibility.

[0034] (π-conjugated conductive polymer) The π-conjugated conductive polymer may be an organic polymer whose main chain is composed of a π-conjugated system, and examples thereof include polypyrrole-based conductive polymers, polythiophene-based conductive polymers, polyacetylene-based conductive polymers, polyphenylene-based conductive polymers, polyphenylenevinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophenevinylene-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.

[0035] Polythiophene-based conductive polymers include polythiophene, poly(3-methylthiophene), poly(3-ethylthiophene), poly(3-propylthiophene), poly(3-butylthiophene), poly(3-hexylthiophene), poly(3-heptylthiophene), poly(3-octylthiophene), poly(3-decylthiophene), poly(3-dodecylthiophene), poly(3-octadecylthiophene), poly(3-bromothiophene), poly(3-chlorothiophene), and poly(3-iodothiophene). thiophene), poly(3-cyanothiophene), poly(3-phenylthiophene), poly(3,4-dimethylthiophene), poly(3,4-dibutylthiophene), poly(3-hydroxythiophene), poly(3-methoxythiophene), poly(3-ethoxythiophene), poly(3-butoxythiophene), poly(3-hexyloxythiophene), poly(3-heptyloxythiophene), poly(3-octyloxythiophene), poly(3-decyloxythiophene), poly(3-dodecyloxythiophene), oxythiophene), poly(3-octadecyloxythiophene), poly(3,4-dihydroxythiophene), poly(3,4-dimethoxythiophene), poly(3,4-diethoxythiophene), poly(3,4-dipropoxythiophene), poly(3,4-dibutoxythiophene), poly(3,4-dihexyloxythiophene), poly(3,4-diheptyloxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-didecyloxythiophene), poly(3,4-di dodecyloxythiophene), poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,4-butylenedioxythiophene), poly(3-methyl-4-methoxythiophene), poly(3-methyl-4-ethoxythiophene), poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), and poly(3-methyl-4-carboxybutylthiophene). Examples of polypyrrole-based conductive polymers include polypyrrole, poly(N-methylpyrrole), poly(3-methylpyrrole), poly(3-ethylpyrrole), poly(3-n-propylpyrrole), poly(3-butylpyrrole), poly(3-octylpyrrole), poly(3-decylpyrrole), poly(3-dodecylpyrrole), poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole), poly(3-carboxypyrrole), poly(3-methyl-4-carboxypyrrole), poly(3-methyl-4-carboxyethylpyrrole), poly(3-methyl-4-carboxybutylpyrrole), poly(3-hydroxypyrrole), poly(3-methoxypyrrole), poly(3-ethoxypyrrole), poly(3-butoxypyrrole), poly(3-hexyloxypyrrole), and poly(3-methyl-4-hexyloxypyrrole). Examples of polyaniline-based conductive polymers include polyaniline, poly(2-methylaniline), poly(3-isobutylaniline), poly(2-anilinesulfonic acid), and poly(3-anilinesulfonic acid). Among these π-conjugated conductive polymers, poly(3,4-ethylenedioxythiophene) is particularly preferable because of its excellent conductivity, transparency, and heat resistance. The conductive composite may contain one type of π-conjugated conductive polymer, or two or more types of polymers.

[0036] (Polyanion) A polyanion is a polymer having two or more monomer units each having an anionic group in the molecule. The anionic group of the polyanion functions as a dopant for a π-conjugated conductive polymer, improving the conductivity of the π-conjugated conductive polymer. The anion group of the polyanion is preferably a sulfo group or a carboxy group. Specific examples of such polyanions include polymers having a sulfo group, such as polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacrylic acid esters having a sulfo group, polymethacrylic acid esters having a sulfo group (for example, poly(4-sulfobutyl methacrylate, polysulfoethyl methacrylate, polymethacryloyloxybenzenesulfonic acid), poly(2-acrylamido-2-methylpropanesulfonic acid), and 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-methylpropanecarboxylic acid), and polyisoprene carboxylic acid. The polyanion may be a homopolymer in which a single monomer is polymerized, or a copolymer in which two or more monomers are polymerized. Among these polyanions, polymers having a sulfo group are preferred, and polystyrene sulfonic acid is more preferred, since they can provide higher electrical conductivity. The polyanions may be used alone or in combination of two or more kinds. The mass average molecular weight of the polyanion is preferably from 20,000 to 1,000,000, and more preferably from 100,000 to 500,000. The mass average molecular weight is the average molecular weight based on mass measured by gel filtration chromatography and calculated in terms of pullulan.

[0037] The content of the polyanion in the conductive complex is preferably, for example, in the range of 1 part by mass to 1000 parts by mass, more preferably 10 parts by mass to 700 parts by mass, and even more preferably 100 parts by mass to 500 parts by mass, relative to 100 parts by mass of the π-conjugated conductive polymer. If the content of the polyanion is equal to or greater than the lower limit, the doping effect on the π-conjugated conductive polymer tends to be stronger, and the conductivity becomes higher. On the other hand, if the content of the polyanion is equal to or less than the upper limit, the π-conjugated conductive polymer can be sufficiently contained, so that sufficient conductivity can be ensured.

[0038] The content of the conductive composite relative to the total mass of the solid electrolyte layer is preferably 1% by mass to 99% by mass, more preferably 50% by mass to 98% by mass, and even more preferably 70% by mass to 97% by mass. The above ranges are preferable because they facilitate a reduction in the equivalent series resistance of the capacitor.

[0039] <Polyol compound> The solid electrolyte layer may further contain one or more compounds having two or more hydroxyl groups (hereinafter, sometimes referred to as polyol compounds) different from the π-conjugated conductive polymer, the polyanion, compound (1), compound (2), and the nitrogen-containing compound. By containing a polyol compound, the equivalent series resistance of the capacitor can be further reduced.

[0040] Examples of the polyol compound include one or more selected from ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, glycerin, pentaerythritol, trimethylolpropane, and trimethylolethane. The polyol compound may be contained as a solvent for the electrolyte, which will be described later.

[0041] When the solid electrolyte layer contains one or more of the polyol compounds, the total content thereof is, for example, preferably 50 parts by mass or more and 2000 parts by mass or less, more preferably 100 parts by mass or more and 1000 parts by mass or less, and even more preferably 300 parts by mass or more and 600 parts by mass or less, relative to 100 parts by mass of the conductive composite contained in the solid electrolyte layer. Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0042] The content of the polyol compound in the solid electrolyte layer can be quantified by disassembling the capacitor, lightly washing the electrolytic solution adhering to the solid electrolyte layer with a solvent for the electrolytic solution, drying at room temperature, and then extracting the polyol compound in the solid electrolyte layer with a solvent such as water, and analyzing it by a method such as liquid chromatography mass spectrometry (LC-MS) or gas chromatography mass spectrometry (GC-MS).

[0043] [Electrolyte] The solid electrolyte layer may contain an electrolyte solution in which an electrolyte is dissolved in a solvent for the electrolyte solution. The higher the electrical conductivity of the electrolyte solution, the more preferable. Examples of the solvent for 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. Examples of the electrolyte include organic acids such as adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, maleic acid, toluic acid, enanthic acid, malonic acid, formic acid, decanedicarboxylic acids such as 1,6-decanedicarboxylic acid and 5,6-decanedicarboxylic acid, octanedicarboxylic acids such as 1,7-octanedicarboxylic acid, azelaic acid, and sebacic acid; boric acid, and polyhydric alcohol complex compounds of boric acid obtained from boric acid and polyhydric alcohol; inorganic acids such as phosphoric acid, carbonic acid, and silicic acid as anion components, and primary amines (methylamine, ethylamine, propylamine, butylamine, etc.). and the like. Examples of such electrolytes include those containing, as a cationic component, a secondary amine (dimethylamine, diethylamine, dipropylamine, methylethylamine, diphenylamine, etc.), a tertiary amine (trimethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo(5,4,0)-undecene-7, etc.), a tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, etc.), etc.

[0044] <<Method of manufacturing a capacitor>> A second aspect of the present invention is a method for producing a capacitor, comprising the steps of applying a conductive polymer dispersion liquid described below to the surface of a dielectric layer formed on the surface of an anode made of a porous valve metal body, and drying the applied conductive polymer dispersion liquid to form a solid electrolyte layer. The method for producing the capacitor of the first aspect can be easily used.

[0045] The manufacturing method of this embodiment preferably includes a step of oxidizing the surface of an anode made of a porous valve metal to form a dielectric layer (dielectric forming step), a step of disposing a cathode at a position facing the dielectric layer (cathode forming step), and a step of forming a solid electrolyte layer on at least a part of the surface of the dielectric layer (film forming step). Each step will be described below with reference to FIG.

[0046] [Dielectric formation process] In this step, the surface of anode 11 made of a porous valve metal is oxidized to form dielectric layer 12. The method for forming dielectric layer 12 is not particularly limited, and examples thereof include a method in which the surface of anode 11 is anodized in an electrolyte for chemical conversion treatment, such as an aqueous solution of ammonium adipate, an aqueous solution of ammonium borate, or an aqueous solution of ammonium phosphate.

[0047] [Cathode formation process] In this step, the cathode 13 is disposed at a position facing the dielectric layer 12. The method for disposing the cathode 13 is not particularly limited, and examples thereof include a method of forming the cathode 13 using a conductive paste such as a carbon paste or a silver paste, and a method of disposing a metal foil such as an aluminum foil facing the dielectric layer 12.

[0048] [Film forming process] In this step, a conductive polymer dispersion liquid, which will be described later, is applied to at least a portion of the surface of the dielectric layer 12, and then dried to form the solid electrolyte layer 14. Examples of the conductive polymer dispersion coating method include immersion (dip coating), comma coating, reverse coating, lip coating, and microgravure coating. Of these, a method of immersing the anode 11 in the conductive polymer dispersion under reduced pressure is preferred. The immersion method allows the conductive polymer dispersion to be sufficiently applied even to the inside of the porous structure on the surface of the dielectric layer 12. After immersion, the anode is removed and subjected to the next drying process.

[0049] Examples of the drying method include room temperature drying, hot air drying, far infrared drying, etc. Among these, hot air drying is preferred. The drying temperature is, for example, preferably 100 to 180° C., and more preferably 120 to 150° C. The drying time is, for example, preferably 0.2 to 1 hour.

[0050] Within the above-mentioned temperature range and drying time, a polymerization reaction occurs via the polymerizable groups at the ends of compounds (1) and (2), improving the adhesion of the formed solid electrolyte layer 14 to the dielectric layer 12, improving the physical strength of the solid electrolyte layer 14, and improving the durability of the solid electrolyte layer 14 against external stress. Furthermore, when the nitrogen-containing compound contained in solid electrolyte layer 14 is a compound having a vinyl-based polymerizable group, the nitrogen-containing compounds undergo a polymerization reaction with each other, or compound (1) or compound (2) undergoes a polymerization reaction with the nitrogen-containing compound in the above-mentioned drying treatment, thereby improving the adhesion of solid electrolyte layer 14 to dielectric layer 12, improving the physical strength of solid electrolyte layer 14, and improving the durability of solid electrolyte layer 14 against external stress.

[0051] After drying, the capacitor can be assembled in the usual manner.

[0052] ≪Conductive polymer dispersion liquid≫ A third aspect of the present invention is a conductive polymer dispersion liquid containing a conductive complex containing a π-conjugated conductive polymer and a polyanion, at least one of the compounds represented by the formula (1) or (2), at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine, and a dispersion medium. The conductive polymer dispersion liquid of this aspect can be used in the method for producing a capacitor of the second aspect.

[0053] The explanation of the conductive complex containing a conjugated conductive polymer and a polyanion in this embodiment is the same as that in the first embodiment, so a duplicated explanation will be omitted. The explanation of the compound represented by formula (1) or (2) in this embodiment is the same as that in the first embodiment, so a duplicated explanation will be omitted. The explanation of the nitrogen-containing aromatic cyclic compound and the tertiary amine in this embodiment is the same as that in the first embodiment, so a duplicated explanation will be omitted. Each of the components that can be contained in the conductive polymer dispersion of this embodiment (conductive polymer dispersion, polyanion, compound (1), compound (2), nitrogen-containing aromatic cyclic compound, tertiary amine, polyol compound, and other optional additives) may be one type or two or more types. When any of the components contained in the conductive polymer dispersion of this embodiment has a vinyl-based polymerizable group, it is preferable that the components are not polymerized with each other via the functional group, which improves the dispersibility and solubility of the components in the dispersion medium.

[0054] <Dispersion medium> The dispersion medium constituting the conductive polymer dispersion of this embodiment is not particularly limited as long as it is a liquid capable of dispersing the conductive complex, and examples thereof include water, an organic solvent, and a mixture of water and an organic solvent. Examples of the organic solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, ester-based solvents, aromatic hydrocarbon-based solvents, etc. These organic solvents may be used alone or in combination of two or more. Examples of the alcohol solvent include methanol, ethanol, isopropanol, n-butanol, t-butanol, and allyl alcohol. Examples of the ether solvent include diethyl ether, dimethyl ether, ethylene glycol, propylene glycol, propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, and propylene glycol dialkyl ethers. 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, and diacetone alcohol. Examples of the ester solvent include ethyl acetate, propyl acetate, and butyl acetate. Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, ethylbenzene, propylbenzene, and isopropylbenzene.

[0055] The content of the π-conjugated conductive polymer and polyanion (i.e., the content of the conductive complex) relative to the total mass of the conductive polymer dispersion is, for example, preferably 0.1 mass % or more and 10 mass % or less, more preferably 0.2 mass % or more and 5 mass % or less, and even more preferably 0.3 mass % or more and 2 mass % or less. When the content is within the above preferred range, the dispersibility of the conductive composite in the conductive polymer dispersion can be further improved.

[0056] The total content of compound (1) and compound (2) contained in the conductive polymer dispersion is preferably 10 parts by mass or more and 5,000 parts by mass or less, more preferably 100 parts by mass or more and 1,000 parts by mass or less, still more preferably 200 parts by mass or more and 800 parts by mass or less, and most preferably 300 parts by mass or more and 600 parts by mass or less, relative to 100 parts by mass of the total of the π-conjugated conductive polymer and polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0057] The total content of the nitrogen-containing compounds contained in the conductive polymer dispersion is preferably such that the pH of the conductive polymer dispersion (25°C) is 2.0 to 8.0, more preferably 2.0 to 5.0, and even more preferably 2.0 to 3.0. Within the above range, the ESR can be further reduced while suppressing a decrease in the capacitance of the produced capacitor.

[0058] When the conductive polymer dispersion contains one or more nitrogen-containing aromatic cyclic compounds having no vinyl-based polymerizable group, the total content thereof is preferably 5 parts 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 even more preferably 15 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0059] When the conductive polymer dispersion contains one or more nitrogen-containing aromatic cyclic compounds having a vinyl-based polymerizable group, the total content thereof is preferably 8 parts by mass or more and 100 parts by mass or less, more preferably 14 parts by mass or more and 70 parts by mass or less, and even more preferably 20 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0060] When the conductive polymer dispersion contains one or more types of tertiary amines that do not have a vinyl-based polymerizable group, the total content thereof is preferably 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 70 parts by mass or less, and even more preferably 25 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0061] When the conductive polymer dispersion contains one or more types of tertiary amines having a vinyl-based polymerizable group, the total content thereof is preferably 10 parts by mass or more and 200 parts by mass or less, more preferably 20 parts by mass or more and 100 parts by mass or less, and even more preferably 30 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0062] The conductive polymer dispersion of this embodiment may contain one or more of the polyols described in the first embodiment. When one or more of the polyol compounds are contained, the total content thereof is, for example, preferably 50 parts by mass or more and 2000 parts by mass or less, more preferably 100 parts by mass or more and 1000 parts by mass or less, and even more preferably 300 parts by mass or more and 600 parts by mass or less, relative to 100 parts by mass in total of the π-conjugated conductive polymer and the polyanion (i.e., 100 parts by mass of the conductive complex). Within the above range, the ESR can be further reduced while suppressing the decrease in the capacitance of the capacitor.

[0063] The conductive polymer dispersion may contain any additive. The content ratio of the additive is appropriately determined depending on the type of additive, but can be, for example, 1 to 1000 parts by mass per 100 parts by mass of the conductive composite. Here, the optional additives are compounds other than the conductive complex, the nitrogen-containing compound, compound (1) and compound (2), the polyol compound, and the dispersion medium (solvent).

[0064] Examples of the optional additives include a surfactant, an inorganic conductive agent, an antifoaming agent, a coupling agent, an antioxidant, and an ultraviolet absorbing agent. The surfactant may be a nonionic, anionic or cationic surfactant, with the nonionic surfactant being preferred from the standpoint of storage stability. Polymer surfactants such as polyvinyl alcohol and polyvinylpyrrolidone may also be added. Examples of the inorganic conductive agent include metal ions, conductive carbon, etc. Metal ions can be generated by dissolving a metal salt in water. The antifoaming agent includes silicone resin, polydimethylsiloxane, silicone oil, and the like. The coupling agent may be a silane coupling agent having a vinyl group, an amino group, an epoxy group, or the like. Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and sugars. Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, oxanilide-based ultraviolet absorbers, hindered amine-based ultraviolet absorbers, and benzoate-based ultraviolet absorbers.

[0065] The conductive polymer dispersion of this embodiment can be produced by mixing the respective components and dispersing the conductive complex by a conventional method. EXAMPLES

[0066] (Production Example 1) 206 g of sodium styrenesulfonate was dissolved in 1000 ml of ion-exchanged water, and while stirring at 80° C., 1.14 g of an oxidizing agent solution of ammonium persulfate previously dissolved in 10 ml of water was added dropwise over 20 minutes, and the solution was stirred for 12 hours. 1000ml of sulfuric acid diluted to 10% by mass was added to the obtained sodium styrene sulfonate-containing solution to obtain a polystyrene sulfonic acid-containing solution, and about 1000ml of the solvent was removed from the polystyrene sulfonic acid-containing solution by ultrafiltration. 2000ml of ion-exchanged water was added to the remaining solution, and about 2000ml of the solvent was removed by ultrafiltration, and the polystyrene sulfonic acid was washed with water. This ultrafiltration operation was repeated three times. Water in the resulting solution was removed under reduced pressure to obtain colorless solid polystyrene sulfonic acid.

[0067] (Production Example 2) 14.2 g of 3,4-ethylenedioxythiophene and a solution in which 36.7 g of the polystyrenesulfonic acid obtained in Production Example 1 was dissolved in 2000 ml of ion-exchanged water were mixed at 20°C. The resulting mixed solution was kept at 20° C., and while stirring, 29.64 g of ammonium persulfate and 8.0 g of an oxidation catalyst solution of ferric sulfate dissolved in 200 ml of ion-exchanged water were slowly added, followed by stirring for 3 hours to carry out the reaction. 2000 ml of ion-exchanged water was added to the reaction solution, and about 2000 ml of the solution was removed by ultrafiltration. This procedure was repeated three times. 200ml of sulfuric acid diluted to 10% by mass and 2000ml of ion-exchanged water were added to the obtained solution, and about 2000ml of the solvent was removed by ultrafiltration. 2000ml of ion-exchanged water was added to the remaining liquid, and about 2000ml of the solvent was removed by ultrafiltration, and the polystyrene sulfonate-doped poly(3,4-ethylenedioxythiophene) (PEDOT-PSS) contained in the solution was washed with water. This operation was repeated eight times to obtain a 1.60% by mass aqueous dispersion of PEDOT-PSS.

[0068] (Production Example 3) After connecting an anode lead terminal to the etched aluminum foil (anode foil), a voltage of 130 V was applied in a 10 mass % aqueous solution of ammonium adipate to perform chemical conversion (oxidation treatment) and form dielectric layers on both sides of the aluminum foil to obtain an anode foil. Next, opposing aluminum cathode foils to which cathode lead terminals were welded were laminated on both sides of the anode foil via a cellulose separator, and the resultant was rolled up into a cylindrical shape to obtain a capacitor element.

[0069] (Production Example 4) 100 g of γ-butyrolactone, 10 g of sulfolane, and 25 g of tetramethylammonium phthalate were mixed and dissolved to obtain a driving electrolyte.

[0070] (Combination example) To 100 parts by mass of the conductive complex contained in the 1.60 mass% PEDOT-PSS aqueous dispersion obtained in Production Example 2, the nitrogen-containing compound and the additive compound were added in the amounts (parts by mass) shown in Table 1, and the mixture was stirred at room temperature. After that, a dispersion process was carried out at a pressure of 100 MPa using a high-pressure disperser, and a conductive polymer dispersion was obtained. The amount of the nitrogen-containing compound added in each formulation example was adjusted so that the molar number was approximately the same and the pH of each conductive polymer dispersion (25° C.) was within the range of 2.0 to 3.0.

[0071] [Table 1]

[0072] The abbreviations in Table 1 stand for the following: "DMAPAA": Dimethylaminopropylacrylamide "A-200": polyethylene glycol #200 di(meth)acrylate: R 1 ,R 2 Compounds represented by =H and n=4 "A-400": polyethylene glycol #400 di(meth)acrylate: R 1 ,R 2 Compounds represented by =H and n=9 "A-600": polyethylene glycol #600 di(meth)acrylate: R 1 ,R 2 Compounds represented by =H and n=14 "A-1000": polyethylene glycol #1000 di(meth)acrylate: R 1 ,R 2 Compounds represented by =H and n=23 "GLY-9E": ethoxylated glycerin triacrylate: R in formula (2) 1 ,R 2 ,R 3 =H, n+m+l=9

[0073] <Capacitor manufacturing> The capacitor element obtained in Production Example 3 was immersed in the conductive polymer dispersion obtained in the above Blending Example under reduced pressure, and then dried for 30 minutes in a hot air dryer at 125°C. This process was repeated once to form a solid electrolyte layer containing a conductive complex on the surface of the dielectric layer. Next, the capacitor element with the solid electrolyte layer formed thereon and the driving electrolyte solution obtained in Production Example 4 were loaded into an aluminum case, and the case was sealed with a rubber seal to obtain a capacitor.

[0074] <Measurement of capacitance and equivalent series resistance> The capacitance (Cap.) at 120 Hz and the equivalent series resistance (ESR) at 100 kHz of each capacitor were measured using an LCR meter ZM2376 (manufactured by NF Corporation). The measurement results are shown in Table 2.

[0075] [Table 2]

[0076] The capacitors of the examples containing the specific nitrogen-containing compound and additive compound exhibited capacitance equivalent to that of the comparative example, and equivalent series resistance superior to that of the comparative example. It should be noted that Examples 1, 2, 4, 5, 7, and 8 are comparative examples.

[0077] When manufacturing the capacitors of each test example, the conductive layer formed on the dielectric layer of the anode foil was carefully observed and the conductive layer was rubbed with a needle. It was found that the conductive layer in Examples 1 to 18 had higher adhesion to the dielectric layer and higher physical strength than Comparative Examples 1 to 4. This result is believed to be due to the fact that compounds (1) and (2) having acrylic groups at both ends of the molecule were used in Examples 1 to 18, and were polymerized by heating during the drying treatment. In other words, it was confirmed that compounds (1) and (2) having polymerizable groups at both ends of the molecule were used in Examples 1 to 18, and therefore the conductive layer had excellent adhesion to the substrate and improved durability against physical stress.

[0078] In addition, when manufacturing the capacitors of each test example, the conductive layer formed on the dielectric layer of the anode foil was carefully observed and the conductive layer was rubbed with a needle. It was found that the conductive layer in Examples 4 to 18 had higher adhesion to the dielectric layer and higher physical strength than Examples 1 to 3. This result is believed to be due to the fact that nitrogen-containing compounds having polymerizable vinyl or acrylic groups were used in Examples 4 to 18, and these were polymerized by heating during the drying treatment. In other words, it was confirmed that, since nitrogen-containing compounds having vinyl or acrylic groups were used in Examples 4 to 18, the adhesion of the conductive layer to the substrate was further improved and the durability against physical stress was further improved. [Explanation of symbols]

[0079] 10 Capacitor 11 Anode 12 Dielectric layer 13 Cathode 14 Solid electrolyte layer

Claims

1. The conductive composite includes a π-conjugated conductive polymer and a polyanion, at least one compound represented by the following formula (1), 1-vinylimidazole which is a nitrogen-containing aromatic cyclic compound, and a dispersion medium, The content of the compound represented by the following formula (1) is more than 312.5 parts by mass and not more than 800 parts by mass relative to 100 parts by mass of the conductive composite, The conductive polymer dispersion has a content of the 1-vinylimidazole of 14 parts by mass or more and 70 parts by mass or less relative to 100 parts by mass of the conductive complex. 【Chemistry 1】 [In formula (1), R １ , R ２ each independently represents a hydrogen atom or an arbitrary substituent, and n represents an integer of 7 to 10.

2. The conductive composite material includes a π-conjugated conductive polymer and a polyanion, at least one compound represented by the following formula (1) or (2), a tertiary amine, and a dispersion medium, The conductive polymer dispersion, wherein the tertiary amine has a vinyl group, an allyl group, an acrylic group or a methacrylic group. 【Chemistry 2】 [In formula (1), R １ , R ２ each independently represents a hydrogen atom or an arbitrary substituent, and n represents an integer. １ , R ２ , R ３ each independently represents a hydrogen atom or an arbitrary substituent, and l, m, and n represent integers, and l+m+n=9 to 20.]

3. 3. The conductive polymer dispersion according to claim 1, wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene), or the polyanion is polystyrenesulfonic acid.

4. The present invention relates to a valve metal porous body, and a cathode made of a conductive material and provided on the dielectric layer opposite to the anode. the solid electrolyte layer contains a conductive complex containing a π-conjugated conductive polymer and a polyanion, at least one of compounds represented by the following formula (1) or a reaction product in which terminal functional groups of one or more compounds represented by the following formula (1) are polymerized with each other, and 1-vinylimidazole which is a nitrogen-containing aromatic cyclic compound, The content of the compound represented by the following formula (1), which may form the reaction product, in the solid electrolyte layer is more than 312.5 parts by mass and not more than 800 parts by mass relative to 100 parts by mass of the conductive composite, The content of the 1-vinylimidazole which may be bonded to the reaction product is 14 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the conductive composite. Capacitor. 【Chemistry 3】 [In formula (1), R １ , R ２ represents a hydrogen atom or an arbitrary substituent, and n represents an integer of 7 to 10.

5. 5. The capacitor according to claim 4, wherein the solid electrolyte layer contains a reaction product in which terminal functional groups of one or more compounds represented by formula (1) are polymerized with each other.

6. The present invention relates to a valve metal porous body, and a cathode made of a conductive material and provided on the dielectric layer opposite to the anode. the solid electrolyte layer comprises a conductive complex containing a π-conjugated conductive polymer and a polyanion, at least one of compounds represented by the following formula (1) or (2), or a reaction product in which terminal functional groups of one or more compounds represented by the following formula (1) are polymerized with each other, or a reaction product in which terminal functional groups of one or more compounds represented by the following formula (2) are polymerized with each other, A tertiary amine having a vinyl group, an allyl group, an acryl group or a methacryl group, In the solid electrolyte layer, at least a part of the tertiary amine is bonded to at least a part of a compound represented by the following formula (1) or (2) via the vinyl group, allyl group, acrylic group or methacrylic group: 【Chemistry 4】 [In formula (1), R １ , R ２ represents a hydrogen atom or an arbitrary substituent, and n represents an integer. １ , R ２ , R ３ represents a hydrogen atom or an arbitrary substituent, and l, m, and n represent integers, and l+m+n=9 to 20.]

7. The capacitor according to any one of claims 4 to 6, wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene), or the polyanion is polystyrenesulfonic acid.

8. A method for producing a capacitor, comprising the steps of applying the conductive polymer dispersion according to any one of claims 1 to 3 to a surface of a dielectric layer formed on a surface of an anode made of a porous body of a valve metal, and drying the applied conductive polymer dispersion to form a solid electrolyte layer.

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