JP2019134143A - Capacitor, manufacturing method thereof, and conductive polymer dispersion - Google Patents

Abstract

To provide a capacitor having a smaller equivalent series resistance and superior heat resistance, a manufacturing method thereof, and a conductive polymer dispersion suitable for the manufacturing of the capacitor.SOLUTION: A capacitor 10 includes an anode 11 made of a porous body of a valve metal, a dielectric layer 12 made of an oxide of the valve metal, a cathode 13 made of a conductive material provided on the opposite side of the dielectric layer from the anode, and a solid electrolyte layer 14 formed between the dielectric layer and the cathode, and the solid electrolyte layer includes a conductive complex including a π-conjugated conductive polymer and a polyanion, and a compound represented by a specific chemical formula including a benzene ring as a basic skeleton.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a capacitor including a solid electrolyte layer containing a π-conjugated conductive polymer, a method for manufacturing the same, and a conductive polymer dispersion.

  For the purpose of reducing the equivalent series resistance of the capacitor, a solid electrolyte layer formed from a conductive polymer dispersion containing poly (3,4-ethylenedioxythiophene) and polystyrene sulfonic acid is formed between a dielectric layer and a cathode. A capacitor disposed between them is known (for example, Patent Document 1).

JP 2014-67949 A

A conventional capacitor manufactured using a conductive polymer dispersion is required to further reduce its equivalent series resistance. In addition, improvement of the heat resistance of the capacitor is also desired.
The present invention provides a capacitor having a lower equivalent series resistance and superior heat resistance, a method for manufacturing the capacitor, and a conductive polymer dispersion suitable for manufacturing the capacitor.

[1] A conductive polymer dispersion containing a conductive complex including a π-conjugated conductive polymer and a polyanion, a compound represented by the following formula (1), and a dispersion medium.
[2] The compound represented by the following formula (1) is at least one of 1,3-bis (2-hydroxyethoxy) benzene and 1,4-bis (2-hydroxyethoxy) benzene, [1] The conductive polymer dispersion described in 1.
[3] The conductive polymer dispersion according to [1] or [2], further containing a nitrogen-containing aromatic cyclic compound.
[4] The conductive polymer dispersion according to [3], wherein the nitrogen-containing aromatic cyclic compound is imidazole.
[5] The high conductivity according to any one of [1] to [4], further comprising at least one compound having two or more hydroxy groups, which is different from the compound represented by the following formula (1). Molecular dispersion.
[6] The conductive polymer dispersion according to any one of [1] to [5], wherein the π-conjugated conductive polymer is poly (3,4-ethylenedioxythiophene).
[7] The conductive polymer dispersion according to any one of [1] to [6], wherein the polyanion is polystyrene sulfonic acid.
[8] 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 opposite side of the dielectric layer from the anode, A solid electrolyte layer formed between a dielectric layer and the cathode, wherein the solid electrolyte layer is represented by the following formula (1): a conductive composite containing a π-conjugated conductive polymer and a polyanion. And a capacitor.
[9] The compound represented by the following formula (1) is at least one of 1,3-bis (2-hydroxyethoxy) benzene and 1,4-bis (2-hydroxyethoxy) benzene, [8] Capacitor.
[10] The capacitor according to [8] or [9], wherein the solid electrolyte layer further contains a nitrogen-containing aromatic cyclic compound.
[11] The capacitor according to [10], wherein the nitrogen-containing aromatic cyclic compound is imidazole.
[12] Any one of [8] to [11], wherein the solid electrolyte layer further contains at least one compound having two or more hydroxy groups, which is different from the compound represented by the following formula (1). Capacitor.
[13] The capacitor according to any one of [8] to [12], wherein the π-conjugated conductive polymer is poly (3,4-ethylenedioxythiophene).
[14] The capacitor according to any one of [8] to [13], wherein the polyanion is polystyrene sulfonic acid.
[15] A step of oxidizing a surface of an anode made of a porous body of valve metal to form a dielectric layer, a step of disposing a cathode at a position facing the dielectric layer, and a surface of the dielectric layer [1] to [7] A method for producing a capacitor, comprising: applying the conductive polymer dispersion according to any one of [7] and drying to form a solid electrolyte layer.

［式（１）中、ｍ、ｎは各々独立して１〜３の整数を表し、Ｒ^１、Ｒ^２は各々独立して炭素数２〜４のアルキレン基を表す。］

[In formula (1), m and n each independently represent an integer of 1 to 3, and R ¹ and R ² each independently represent an alkylene group having 2 to 4 carbon atoms. ]

The capacitor of the present invention is excellent in heat resistance and has an equivalent series resistance smaller than that of the conventional one, which contributes to high performance of electronic equipment.
According to the method for manufacturing a capacitor of the present invention, a capacitor having excellent heat resistance and a small equivalent series resistance can be easily manufactured.
The conductive polymer dispersion of the present invention is suitable for forming a solid electrolyte layer of a capacitor having excellent heat resistance and low equivalent series resistance.

It is sectional drawing which shows one Embodiment of the capacitor of this invention.

<Capacitor>
One embodiment of the capacitor of the present invention will be described. As shown in FIG. 1, the capacitor 10 of this embodiment is formed on the surface of the anode 11 made of a porous body of the valve metal, the dielectric layer 12 made of the oxide of the valve metal, and the dielectric layer 12. A solid electrolyte layer 14 and a cathode 13 provided on the most front side are provided. 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.

Examples of the valve metal constituting the anode 11 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Of 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 oxidizing the surface, or oxidizing the surface of a sintered body of tantalum particles and niobium particles into pellets. Can be mentioned. What was processed in this way becomes a porous body having irregularities formed on the surface.

  The dielectric layer 12 in the present embodiment is a layer formed by oxidizing the surface of the anode 11. For example, the surface of the anode 11 of the metal body is anodized in an electrolytic solution such as an aqueous solution of ammonium adipate. It is formed by. Therefore, as shown in FIG. 1, the dielectric layer 12 is also uneven as in the anode 11.

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

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 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 or may not be constant, and examples thereof include a thickness of 1 μm or more and 100 μm or less.

  The solid electrolyte layer 14 includes one or more compounds represented by the following formula (1) (hereinafter sometimes referred to as compound 1), a π-conjugated conductive polymer and a polyanion described in detail later. And a conductive composite.

［式（１）中、ｍ、ｎは各々独立して１〜３の整数を表し、Ｒ^１、Ｒ^２は各々独立して炭素数２〜４のアルキレン基を表す。］

[In formula (1), m and n each independently represent an integer of 1 to 3, and R ¹ and R ² each independently represent an alkylene group having 2 to 4 carbon atoms. ]

  In the above formula (1), m and n are preferably 1 or 2, and more preferably 1, from the viewpoint of reducing the ESR of the capacitor and increasing the heat resistance.

In the formula (1), the relative arrangement of the two functional groups having R ¹ or R ² bonded to the benzene ring via an oxygen atom may be any of the ortho, meta, and para positions. From the viewpoint of reducing ESR and increasing heat resistance, the meta position and the para position are preferable, and the meta position is more preferable.

In the formula (1), the alkylene group having 2 to 4 carbon atoms of R ¹ and R ² is each independently an ethylene group, a propylene group (—CH (CH ₃ ) —CH ₂ —) or a trimethylene group (— CH ₂ —CH ₂ —CH ₂ —) is preferred. Here, the directions of the left end and the right end of the propylene group are not distinguished. If R ¹ and R ² are a plurality each of each of R ¹ and R ² may be the same as each other or may be different.

  Specific examples of the compound 1 represented by the formula (1) include 1,3-bis (2-hydroxyethoxy) benzene and 1,4-bis (2-hydroxyethoxy) benzene.

The total content of Compound 1 contained in the solid electrolyte layer 14 is preferably 1 part by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the conductive composite described later contained in the solid electrolyte layer 14, and 10 parts by mass. It is more preferably 500 parts by mass or less, further preferably 20 parts by mass or more and 200 parts by mass or less, and particularly preferably 50 parts by mass or more and 100 parts by mass or less.
The above range is preferable because the equivalent series resistance of the capacitor is more likely to be lowered and the heat resistance is more likely to be improved.
The type of compound 1 contained in the solid electrolyte layer 14 may be one type or two or more types.

Next, a conductive composite containing a π-conjugated conductive polymer and a polyanion contained in the solid electrolyte layer 14 will be described.
The π-conjugated conductive polymer is not particularly limited as long as the main chain is an organic polymer composed of a π-conjugated system. For example, a polypyrrole-based conductive polymer, a polythiophene-based conductive polymer, a polyacetylene-based polymer Conductive polymers, polyphenylene conductive polymers, polyphenylene vinylene conductive polymers, polyaniline conductive polymers, polyacene conductive polymers, polythiophene vinylene conductive polymers, and copolymers thereof Can be mentioned. From the viewpoint of stability in the air, polypyrrole conductive polymers, polythiophene conductive polymers and polyaniline conductive polymers are preferable, and polythiophene conductive polymers are more preferable.

  Examples of the polythiophene-based conductive polymer include polythiophene, poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), poly (3-butylthiophene), and poly (3-hexyl). Thiophene), 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-dibutyl) Thiophene), 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 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-carboxy) Ethylthiophene) and poly (3-methyl-4-carboxybutylthiophene).

  Examples of the polypyrrole-based conductive polymer include polypyrrole, poly (N-methylpyrrole), poly (3-methylpyrrole), poly (3-ethylpyrrole), poly (3-n-propylpyrrole), and 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-hydroxy Pyrrole), poly (3-methoxypyrrole), poly (3-ethoxypyrrole), poly (3-butoxypyrrole), poly (3 Hexyloxy pyrrole), poly (3-methyl-4-hexyloxy-pyrrole) and the like.

Examples of the polyaniline-based conductive polymer include polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), poly (2-aniline sulfonic acid), and poly (3-aniline sulfonic acid).
Among the π-conjugated conductive polymers exemplified above, poly (3,4-ethylenedioxythiophene) is particularly preferable from the viewpoint of conductivity and heat resistance.
One kind of π-conjugated conductive polymer may be used alone, or two or more kinds may be used in combination.

The polyanion is a polymer having two or more monomer units having an anion group in the molecule. The anion group of the polyanion functions as a dopant for the π-conjugated conductive polymer, and can improve 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 polyanions include polystyrene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyacryl sulfonic acid, polymethacryl sulfonic acid, poly (2-acrylamido-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, poly Polymers having a sulfonic acid group such as sulfoethyl methacrylate, poly (4-sulfobutyl methacrylate), polymethacryloxybenzene sulfonic acid, polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacryl carboxylic acid, polymethacrylic acid Examples thereof include polymers having a carboxylic acid group such as carboxylic acid, poly (2-acrylamido-2-methylpropanecarboxylic acid), polyisoprene carboxylic acid, and polyacrylic acid. These homopolymers may be sufficient and 2 or more types of copolymers may be sufficient.
Among these polyanions, a polymer having a sulfonic acid group is preferable and polystyrene sulfonic acid is more preferable because conductivity can be further increased.
A polyanion may be used individually by 1 type, and may use 2 or more types together.
The mass average molecular weight of the polyanion is preferably 20,000 or more and 1,000,000 or less, and more preferably 100,000 or more and 500,000 or less.
The mass average molecular weight of the polyanion is a value obtained by measuring by gel permeation chromatography and obtaining the standard material as polystyrene.

  The content ratio of the polyanion in the conductive complex is preferably in the range of 1 part by mass to 1000 parts by mass with respect to 100 parts by mass of the π-conjugated conductive polymer, and 10 parts by mass to 700 parts by mass. The following range is more preferable, and the range of 100 parts by mass or more and 500 parts by mass or less is more preferable. When the polyanion content is at least the above lower limit, the doping effect on the π-conjugated conductive polymer tends to be strong, and sufficient conductivity is easily obtained. Further, the conductivity in the conductive polymer dispersion is high. The dispersibility of the composite is increased. Further, when the content of the polyanion is not more than the above upper limit value, the relative content of the π-conjugated conductive polymer is increased, and sufficient conductivity is easily obtained.

  A conductive complex is formed by coordinating and doping a polyanion with a π-conjugated conductive polymer. From the viewpoint of improving the conductivity and dispersibility of the conductive composite, it is preferable that all anionic groups have an excess anionic group that does not contribute to doping, rather than doping the π-conjugated conductive polymer.

  The content of the conductive composite with respect to the total mass of the solid electrolyte layer 14 is preferably 1% by mass to 90% by mass, more preferably 10% by mass to 70% by mass, and further more preferably 20% by mass to 60% by mass. preferable. The above range is preferable because the equivalent series resistance of the capacitor is more likely to decrease.

  The solid electrolyte layer 14 may contain one or more nitrogen-containing compounds. By including the nitrogen-containing compound in the solid electrolyte layer 14, the equivalent series resistance of the capacitor can be further reduced.

Examples of the nitrogen-containing compound include the following amine compounds and nitrogen-containing aromatic cyclic compounds. When at least one of these amine compounds and nitrogen-containing aromatic cyclic compounds is contained in the solid electrolyte layer 14, the equivalent series resistance of the capacitor may be further reduced.
The amine compound is a compound having an amino group, and the amino group reacts with the anion group of the polyanion.
The amine compound may be any of primary amine, secondary amine, tertiary amine, and quaternary ammonium salt. Moreover, an amine compound may be used individually by 1 type, and may use 2 or more types together.
The amine compound is a linear or branched alkyl group having 2 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or an alkylene group having 2 to 12 carbon atoms. And a substituent selected from an arylene group having 6 to 12 carbon atoms, an aralkylene group having 7 to 12 carbon atoms, and an oxyalkylene group having 2 to 12 carbon atoms.
Specific examples of the primary amine include aniline, toluidine, benzylamine, and ethanolamine.
Specific examples of the secondary amine include diethanolamine, dimethylamine, diethylamine, dipropylamine, diphenylamine, dibenzylamine, and dinaphthylamine.
Specific examples of the tertiary amine include triethanolamine, trimethylamine, triethylamine, tripropylamine, tributylamine, trioctylamine, triphenylamine, tribenzylamine, and trinaphthylamine.
Specific examples of the quaternary ammonium salt include tetramethylammonium salt, tetraethylammonium salt, tetrapropylammonium salt, tetraphenylammonium salt, tetrabenzylammonium salt, tetranaphthylammonium salt and the like. A hydroxide ion is mentioned as an anion which becomes a pair of ammonium.
Of these amine compounds, tertiary amines are preferred, and triethylamine and tripropylamine are more preferred.
Examples of the nitrogen-containing aromatic cyclic compound (aromatic compound in which at least one nitrogen atom forms a ring structure) 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 -Hydroxybenz Imidazole, 2- (2-pyridyl) benzimidazole and pyridine.
Of these nitrogen-containing aromatic cyclic compounds, imidazole is more preferred.

The total content of the nitrogen-containing compounds contained in the solid electrolyte layer 14 is preferably 1 part by mass or more and 100 parts by mass or less, preferably 5 parts by mass with respect to 100 parts by mass of the conductive composite contained in the solid electrolyte layer 14. The content is more preferably 30 parts by mass or less, and still more preferably 10 parts by mass or more and 20 parts by mass or less.
The above range is preferable because the equivalent series resistance of the capacitor is more likely to be lowered and the heat resistance is more likely to be improved.
The type of the nitrogen-containing compound contained in the solid electrolyte layer 14 may be one type or two or more types.

In the solid electrolyte layer 14, one or more of compounds having two or more hydroxy groups (hereinafter sometimes referred to as polyol compounds) different from the compound 1, the conductive complex, and the nitrogen-containing compound are included. Furthermore, it is preferable that it is contained. By containing the polyol compound, ESR of the capacitor can be further reduced.
Examples of the polyol compound include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, glycerin, pentaerythritol, trimethylolpropane, 1,3,5-tris (2-hydroxyethyl) isocyanurate, and triglyceride. One or more selected from methylolethane can be mentioned.
The polyol compound may be contained as an electrolyte solvent or a dispersion medium for the conductive complex described below.

The total content of the polyol compound contained in the solid electrolyte layer 14 is preferably 100 parts by mass or more and 10,000 parts by mass or less, and 200 parts by mass or more with respect to 100 parts by mass of the conductive composite contained in the solid electrolyte layer 14. 2000 mass parts or less are more preferable, and 300 mass parts or more and 1000 mass parts or less are still more preferable.
The above range is preferable because the equivalent series resistance of the capacitor is more likely to be lowered and the heat resistance is more likely to be improved.
The polyol compound contained in the solid electrolyte layer 14 may be one type or two or more types.
In the case of containing diethylene glycol and 1,3,5-tris (2-hydroxyethyl) isocyanurate as the polyol compound, the content ratio of both is diethylene glycol: 1,3,5- Tris (2-hydroxyethyl) isocyanurate = 10: 10 to 10: 1 (mass ratio) is preferable.

The solid electrolyte layer 14 may include an electrolytic solution in which an electrolyte is dissolved in an electrolytic solution solvent. The higher the electric conductivity of the electrolytic solution, the better.
Examples of the electrolyte solution solvent include alcohol solvents such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, and glycerin, lactone solvents such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone, Examples thereof include amide solvents such as N-methylformamide, N, N-dimethylformamide, N-methylacetamide and N-methylpyrrolidinone, nitrile solvents such as acetonitrile and 3-methoxypropionitrile, water and the like.
Examples of the electrolyte include adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, maleic acid, toluic acid, enanthic acid, malonic acid, formic acid, 1,6-decanedicarboxylic acid, 5 Decane dicarboxylic acid such as 1,6-decanedicarboxylic acid, octane dicarboxylic acid such as 1,7-octane dicarboxylic acid, organic acid such as azelaic acid and sebacic acid; or boric acid, a large amount of boric acid obtained from boric acid and polyhydric alcohol Monohydric alcohol complex compounds: primary acids (methylamine, ethylamine, propylamine, butylamine, ethylenediamine, etc.), secondary amines (dimethylamine, diethylamine, diamine) containing inorganic acids such as phosphoric acid, carbonic acid, and silicic acid as anion components Propylamine, methylethylamine, diphenylamine, etc.), tertiary amine ( Limethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo (5,4,0) -undecene-7, etc.), tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, Electrolytes having a cation component such as methyltriethylammonium and dimethyldiethylammonium).

<Effect>
When the solid electrolyte layer of the capacitor of the present invention contains the compound represented by the formula (1), the equivalent series resistance of the capacitor can be reduced more than before without reducing the capacitance. Although this mechanism has not been elucidated, it is presumed that the equivalent series resistance has been reduced by the compound improving the conductivity of the solid electrolyte layer.
Moreover, the heat resistance of a capacitor can be improved because the solid electrolyte layer of the capacitor | condenser of this invention contains the compound represented by said Formula (1). Although this mechanism is not yet elucidated, it is presumed that the heat resistance of the compound is improved by improving the stability of the conductive composite contained in the solid electrolyte layer.

<< Capacitor Manufacturing Method, Conductive Polymer Dispersion >>
The capacitor according to the present invention includes a step of forming a dielectric layer by oxidizing the surface of the anode made of a porous body of valve metal (dielectric formation step), and disposing a cathode at a position facing the dielectric layer. It can be manufactured by a step (cathode formation step) and a step of applying a conductive polymer dispersion to at least a part of the surface of the dielectric layer and drying to form a solid electrolyte layer.

The conductive polymer dispersion is a dispersion in which one or more compounds represented by the formula (1) are included, and a conductive complex including a π-conjugated conductive polymer and a polyanion is further dispersed. is there.
The conductive polymer dispersion may contain the nitrogen-containing compound, the polyol compound, an additive described later, and the like.

The dielectric layer forming step is a step of forming the dielectric layer 12 by oxidizing the surface of the anode 11 made of a porous body of valve metal.
Examples of the method for forming the dielectric layer 12 include a method in which the surface of the anode 11 is anodized in an electrolytic solution 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. .

The cathode forming step is a step of disposing the cathode 13 at a position facing the dielectric layer 12.
Examples of the method of arranging the cathode 13 include a method of forming the cathode 13 using a conductive paste such as carbon paste and silver paste, and a method of arranging a metal foil such as an aluminum foil opposite to the dielectric layer 12. It is done.

  The solid electrolyte layer forming step is a step of forming the solid electrolyte layer 14 by applying the conductive polymer dispersion on at least a part of the surface of the dielectric layer 12 and drying it.

The dispersion medium constituting the conductive polymer dispersion is not particularly limited as long as it is a liquid that can disperse the conductive composite, and examples thereof include water, an organic solvent, or a mixture of water and an organic solvent. It is done.
Examples of the organic solvent include alcohol solvents, ether solvents, ketone solvents, ester solvents, aromatic hydrocarbon solvents, and the like. These organic solvents may be used individually by 1 type, and may use 2 or more types together.
Examples of the alcohol solvent include methanol, ethanol, isopropanol, n-butanol, t-butanol, and allyl alcohol.
Examples of ether solvents include propylene glycol monoalkyl ethers such as diethyl ether, dimethyl ether, ethylene glycol, propylene glycol, propylene glycol monomethyl ether, and propylene glycol dialkyl ether.
Examples of the ketone solvent include diethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisopropyl ketone, methyl ethyl ketone, acetone, diacetone alcohol and the like.
Examples of the ester solvent include ethyl acetate, propyl acetate, butyl acetate and the like.
Examples of the aromatic hydrocarbon solvent include benzene, toluene, xylene, ethylbenzene, propylbenzene, isopropylbenzene, and the like.

Examples of the additive include a surfactant, an inorganic conductive agent, an antifoaming agent, a coupling agent, an antioxidant, and an ultraviolet absorber. However, the additive is a compound other than the compound represented by the formula (1), the conductive composite, the nitrogen-containing compound, the polyol compound, and the solvent (dispersion medium).
Examples of the surfactant include nonionic, anionic and cationic surfactants, and nonionic surfactants are preferred from the viewpoint of storage stability. Moreover, you may add polymer type surfactants, such as polyvinyl alcohol and polyvinylpyrrolidone.
Examples of the inorganic conductive agent include metal ions and conductive carbon. Metal ions can be generated by dissolving a metal salt in water.
Examples of the antifoaming agent include silicone resin, polydimethylsiloxane, and silicone oil.
Examples of the coupling agent include silane coupling agents having a vinyl group, an amino group, an epoxy group, and the like.
Examples of the antioxidant include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, and saccharides.
Examples of UV absorbers include benzotriazole UV absorbers, benzophenone UV absorbers, salicylate UV absorbers, cyanoacrylate UV absorbers, oxanilide UV absorbers, hindered amine UV absorbers, and benzoate UV absorbers. Is mentioned.

  The content of the conductive composite with respect to the total mass of the conductive polymer dispersion is not particularly limited, and is preferably a content that provides a viscosity that can be easily applied. Specifically, for example, 0.1% by mass to 10% by mass is preferable, 0.5% by mass to 5% by mass is more preferable, and 1% by mass to 2% by mass is more preferable.

The total content of the compound represented by the formula (1) with respect to the total mass of the conductive polymer dispersion is not particularly limited, and a content that makes it easy to apply is preferable. Specifically, for example, 0.1% by mass to 20% by mass is preferable, 0.5% by mass to 10% by mass is more preferable, and 1% by mass to 5% by mass is more preferable.
In the case where the dispersion medium constituting the conductive polymer dispersion is an aqueous dispersion medium containing 50% by mass or more of water, in consideration of the low solubility in water of the formula (1), the content is 0.1 mass% or more and 3 mass% or less are preferable, and 0.5 mass% or more and 2 mass% or less are more preferable.

  When the conductive polymer dispersion contains the nitrogen-containing compound, the content ratio is appropriately determined according to the type of the nitrogen-containing compound, for example, for 100 parts by mass of the solid content of the conductive composite, For example, 1 part by mass or more and 100 parts by mass or less is preferable, 5 parts by mass or more and 50 parts by mass or less are more preferable, and 10 parts by mass or more and 20 parts by mass or less are more preferable.

  When the conductive polymer dispersion contains the polyol compound, the content ratio is appropriately determined according to the type of the polyol compound. For example, for 100 parts by mass of the solid content of the conductive composite, 100 parts by mass or more and 10000 parts by mass or less are preferable, 200 parts by mass or more and 2000 parts by mass or less are more preferable, and 300 parts by mass or more and 1000 parts by mass or less are more preferable.

  When the conductive polymer dispersion contains the additive, the content ratio is appropriately determined according to the type of the additive. For example, for 100 parts by mass of the solid content of the conductive composite, It can be in the range of 1 to 1000 parts by mass.

Examples of a method for preparing the conductive polymer dispersion include a method in which a precursor monomer that forms a π-conjugated conductive polymer is oxidatively polymerized in the presence of a polyanion and a dispersion medium.
To the obtained conductive polymer dispersion, the compound represented by the formula (1) is added, and if necessary, the nitrogen-containing compound, the compound having two or more hydroxy groups, an additive, and the like Can be added.
For the purpose of improving the dispersibility of each material contained in the conductive polymer dispersion, it is preferable to perform a known high dispersion treatment in which the conductive polymer dispersion is dispersed while applying a shearing force before coating.

As a method for applying the conductive polymer dispersion, for example, dipping (dip coating), comma coating, reverse coating, lip coating, microgravure coating, or the like can be applied. Among these, immersion is preferable from the viewpoint that the solid electrolyte layer 14 can be easily formed between the dielectric layer 12 and the cathode 13.
Examples of the drying method include room temperature drying, hot air drying, and far infrared drying.

The capacitor and the manufacturing method thereof according to the present invention are not limited to the above-described embodiments.
In the capacitor of the present invention, a separator may be provided between the dielectric layer and the cathode.
Examples of the capacitor in which a separator is provided between the dielectric layer and the cathode include a wound capacitor.
Examples of the separator include a sheet (including a non-woven fabric) made of cellulose, polyvinyl alcohol, polyester, polyethylene, polystyrene, polypropylene, polyimide, polyamide, polyvinylidene fluoride, a non-woven fabric of glass fiber, and the like.
The density of the separator is more preferably it is 0.1 g / cm ³ or more 1.0 g / cm ³ or less in the range is preferable, 0.2 g / cm ³ or more 0.8 g / cm ³ or less.
In the case of providing a separator, a method of forming a cathode by impregnating the separator with a carbon paste or a silver paste can also be applied.

(Production Example 1)
Dissolve 206 g of sodium styrenesulfonate in 1000 ml of ion-exchanged water and, while stirring at 80 ° C., add dropwise 1.14 g of ammonium persulfate oxidizer solution previously dissolved in 10 ml of water for 20 minutes. Stir.
1000 ml of sulfuric acid diluted to 10% by mass was added to the obtained sodium styrenesulfonate-containing solution, and about 1000 ml of the polystyrenesulfonic acid-containing solution was removed by ultrafiltration. 2000 ml of ion-exchanged water was added to the remaining liquid, about 2000 ml of solvent was removed by ultrafiltration, and polystyrene sulfonic acid was washed with water. This ultrafiltration operation was repeated three times.
Water in the obtained solution was removed under reduced pressure to obtain colorless solid polystyrene sulfonic acid.

(Production Example 2)
A solution prepared by dissolving 14.2 g of 3,4-ethylenedioxythiophene and 36.7 g of the polystyrene sulfonic acid obtained in Production Example 1 in 2000 ml of ion-exchanged water was mixed at 20 ° C.
The obtained mixed solution was kept at 20 ° C., and while stirring, 29.64 g of ammonium persulfate dissolved in 200 ml of ion exchange water and 8.0 g of ferric sulfate oxidation catalyst solution were slowly added for 3 hours. The reaction was stirred.
2000 ml of ion-exchanged water was added to the obtained reaction solution, and about 2000 ml of solution was removed by ultrafiltration. This operation was repeated three times.
To the obtained solution, 200 ml of sulfuric acid diluted to 10% by mass and 2000 ml of ion exchange water were added, and about 2000 ml of solvent was removed by ultrafiltration. 2000 ml of ion-exchanged water was added to the remaining liquid, about 2000 ml of the solvent was removed by ultrafiltration, and polystyrenesulfonic acid-doped poly (3,4-ethylenedioxythiophene) (PEDOT-PSS) was washed with water. This operation was repeated 8 times to obtain 1.60% by mass of polystyrenesulfonic acid-doped poly (3,4-ethylenedioxythiophene) aqueous dispersion (PEDOT-PSS aqueous dispersion).

(Production Example 3)
After connecting the anode lead terminal to the etched aluminum foil (anode foil), a voltage of 130 V was applied in an aqueous solution of 10% by weight ammonium adipate to form (oxidize) the dielectric layer on both sides of the aluminum foil. An anode foil was obtained by forming.
Next, on both surfaces of the anode foil, an opposing aluminum cathode foil with cathode lead terminals welded was laminated via a cellulose separator, and this was wound into a cylindrical shape to obtain a capacitor element.

Example 1
Commercially available 1,3-bis (2-hydroxyethoxy) benzene (abbreviation: 1,3-BHEB) 2.0 mass with 1.60 mass% PEDOT-PSS aqueous dispersion obtained in Production Example 2 Parts (125 parts by mass with respect to 100 parts by mass of the conductive composite) were stirred at room temperature, and then subjected to dispersion treatment at a pressure of 100 MPa using a high-pressure disperser to obtain a conductive polymer dispersion.
After immersing the capacitor element obtained in Production Example 3 in a conductive polymer dispersion under reduced pressure, the process of drying with a hot air dryer at 125 ° C. for 30 minutes was repeated twice to make the conductive element conductive on the surface of the dielectric layer. A solid electrolyte layer containing the composite was formed.
Next, a capacitor element having a solid electrolyte layer formed thereon was loaded into an aluminum case and sealed with a sealing rubber to obtain a capacitor.

(Comparative Example 1)
A capacitor was obtained in the same manner as in Example 1 except that 1,3-bis (2-hydroxyethoxy) benzene was not added.

<Evaluation>
[Capacitance / Equivalent Series Resistance]
For the capacitors of Example 1 and Comparative Example 1, using an LCR meter ZM2376 (manufactured by NF Circuit Design Block Co., Ltd.), the capacitance (C ₀ ) at 120 Hz and the equivalent series resistance (ESR ₀ ) at 100 kHz Was measured. The measurement results are shown in Table 1.
[Heat resistance test]
The capacitors of Example 1 and Comparative Example 1 were left standing in a hot air dryer at 135 ° C., taken out after 500 hours, and cooled at room temperature for 30 minutes. The capacitor after cooling, using an LCR meter ZM2376 ((KK) NF circuit design block), the electrostatic capacity at 120 Hz _(C 1), and were measured equivalent series resistance (ESR ₁₎ at 100kHz. The measurement results are shown in Table 1.
Further, as the amount of change before and after the heat resistance test were determined _{△ C = C 1 / C 0} , △ ESR = ESR 1 / ESR 0. Table 1 also shows ΔC and ΔESR.

The capacitor of Example 1 provided with the solid electrolyte layer containing the compound represented by the formula (1) had a sufficient capacitance, and the equivalent series resistance was greatly reduced. Moreover, the value of the equivalent series resistance after the heat resistance test was also small. Furthermore, the amount of change in equivalent series resistance (ΔESR) after the heat resistance test was also sufficiently small. Although figures of △ ESR Example 1 larger than that of Comparative Example 1, since the ESR ₁ of Example 1 is sufficiently smaller than the ESR ₀ and ESR ₁ of Comparative Example 1, heat of the capacitor of Example 1 The property is excellent.
The capacitor of Comparative Example 1 including the solid electrolyte layer not containing the compound represented by the formula (1) had a capacitance equivalent to that of the example, but the equivalent series resistance was larger than that of the example. Moreover, the value of the equivalent series resistance after the heat resistance test was also large.

(Example 2)
To 100 parts by mass of the 1.60 mass% PEDOT-PSS aqueous dispersion obtained in Production Example 2, 2.0 parts by mass of 1,3-bis (2-hydroxyethoxy) benzene and 0.3 parts by mass of imidazole ( 18.8 parts by mass with respect to 100 parts by mass of the conductive composite) was stirred at room temperature, and then subjected to dispersion treatment at a pressure of 100 MPa using a high-pressure disperser to obtain a conductive polymer dispersion.
After immersing the capacitor element obtained in Production Example 3 in a conductive polymer dispersion under reduced pressure, the process of drying with a hot air dryer at 125 ° C. for 30 minutes was repeated twice to make the conductive element conductive on the surface of the dielectric layer. A solid electrolyte layer containing the composite was formed.
Next, a capacitor element having a solid electrolyte layer formed thereon was loaded into an aluminum case and sealed with a sealing rubber to obtain a capacitor.

Example 3
A capacitor was obtained in the same manner as in Example 2 except that the amount of 1,3-bis (2-hydroxyethoxy) benzene added was changed to 1.0 part by mass.

Example 4
1,3-bis (2-hydroxyethoxy) benzene was changed to commercially available 1,4-bis (2-hydroxyethoxy) benzene (abbreviation: 1,4-BHEB), and the amount added was 1.0 parts by mass. A capacitor was obtained in the same manner as in Example 2 except for the change.

(Example 5)
A capacitor was obtained in the same manner as in Example 2 except that the amount of imidazole added was 0.4 parts by mass.

(Comparative Example 2)
A capacitor was obtained in the same manner as in Example 2 except that 1,3-bis (2-hydroxyethoxy) benzene was not added.

<Evaluation>
[Capacitance / Equivalent Series Resistance]
For the capacitors of Examples 2 to 5 and Comparative Example 2, using an LCR meter ZM2376 (manufactured by NF circuit design block), capacitance (C ₀ ) at 120 Hz and equivalent series resistance (ESR) at 100 kHz ₀ ) was measured. The measurement results are shown in Table 2.
[Heat resistance test]
The capacitors of Examples 2 to 5 and Comparative Example 2 were placed in a hot air dryer at 135 ° C., taken out after 500 hours, and cooled at room temperature for 30 minutes. The capacitor after cooling, using an LCR meter ZM2376 ((KK) NF circuit design block), the electrostatic capacity at 120 Hz _(C 1), and were measured equivalent series resistance (ESR ₁₎ at 100kHz. The measurement results are shown in Table 2.
Further, as the amount of change before and after the heat resistance test were determined _{△ C = C 1 / C 0} , △ ESR = ESR 1 / ESR 0. ΔC and ΔESR are also shown in Table 2.

The capacitors of Examples 2 to 5 provided with the solid electrolyte layer containing the compound represented by the formula (1) and imidazole had sufficient capacitance, and the equivalent series resistance was greatly reduced. Furthermore, the amount of change in equivalent series resistance after the heat resistance test was also small.
The capacitor of Comparative Example 2 provided with the solid electrolyte layer not containing the compound represented by the formula (1) had a capacitance equivalent to that of the example, but the equivalent series resistance was larger than that of the example. Furthermore, the amount of change in equivalent series resistance after the heat resistance test was also large.

(Example 6)
To 100 parts by mass of the 1.60% by mass PEDOT-PSS aqueous dispersion obtained in Production Example 2, 1.0 part by mass of 1,3-bis (2-hydroxyethoxy) benzene (to 100 parts by mass of the conductive composite) 62.5 parts by mass), 0.3 part by mass of imidazole (18.8 parts by mass with respect to 100 parts by mass of the conductive composite), 5.0 parts by mass of diethylene glycol were added, and the mixture was stirred at room temperature. Using a disperser, a dispersion treatment was performed at a pressure of 100 MPa to obtain a conductive polymer dispersion.
After immersing the capacitor element obtained in Production Example 3 in a conductive polymer dispersion under reduced pressure, the process of drying with a hot air dryer at 125 ° C. for 30 minutes was repeated twice to make the conductive element conductive on the surface of the dielectric layer. A solid electrolyte layer containing the composite was formed.
Next, a capacitor element having a solid electrolyte layer formed thereon was loaded into an aluminum case and sealed with a sealing rubber to obtain a capacitor.

(Example 7)
A capacitor was obtained in the same manner as in Example 6 except that 1,3-bis (2-hydroxyethoxy) benzene was changed to 1,4-bis (2-hydroxyethoxy) benzene.

(Example 8)
Further, a capacitor was obtained in the same manner as in Example 6 except that 3.0 parts by mass of 1,3,5-tris (2-hydroxyethyl) isocyanurate was added.

Example 9
Further, 3.0 parts by mass of 1,3,5-tris (2-hydroxyethyl) isocyanurate was added, and 1,3-bis (2-hydroxyethoxy) benzene was converted to 1,4-bis (2-hydroxyethoxy) benzene. A capacitor was obtained in the same manner as in Example 6 except that

(Comparative Example 3)
A capacitor was obtained in the same manner as in Example 6 except that 1,3-bis (2-hydroxyethoxy) benzene was not added.

<Evaluation>
[Capacitance / Equivalent Series Resistance]
For the capacitors of Examples 6 to 9 and Comparative Example 3, using an LCR meter ZM2376 (manufactured by NF Circuit Design Block Co., Ltd.), capacitance (C ₀ ) at 120 Hz and equivalent series resistance (ESR) at 100 kHz ₀ ) was measured. The measurement results are shown in Table 3.
[Heat resistance test]
The capacitors of Examples 6 to 9 and Comparative Example 3 were left standing in a hot air dryer at 135 ° C., taken out after 500 hours, and cooled at room temperature for 30 minutes. The capacitor after cooling, using an LCR meter ZM2376 ((KK) NF circuit design block), the electrostatic capacity at 120 Hz _(C 1), and were measured equivalent series resistance (ESR ₁₎ at 100kHz. The measurement results are shown in Table 3.
Further, as the amount of change before and after the heat resistance test were determined _{△ C = C 1 / C 0} , △ ESR = ESR 1 / ESR 0. Table 3 also shows ΔC and ΔESR.

The capacitors of Examples 6 to 9 including the solid electrolyte layer containing the compound represented by the formula (1), imidazole and diethylene glycol had a sufficient capacitance, and the equivalent series resistance was greatly reduced. Furthermore, the amount of change in equivalent series resistance after the heat resistance test was also small.
The capacitor of Comparative Example 3 provided with the solid electrolyte layer not containing the compound represented by the formula (1) had a capacitance equivalent to that of the example, but the equivalent series resistance was larger than that of the example. Furthermore, the amount of change in equivalent series resistance after the heat resistance test was also large.

10 Capacitor 11 Anode 12 Dielectric Layer 13 Cathode 14 Solid Electrolyte Layer

Claims (15)

A conductive polymer dispersion containing a conductive complex containing a π-conjugated conductive polymer and a polyanion, a compound represented by the following formula (1), and a dispersion medium.

[In formula (1), m and n each independently represent an integer of 1 to 3, and R ¹ and R ² each independently represent an alkylene group having 2 to 4 carbon atoms. ]   The compound represented by the formula (1) is at least one of 1,3-bis (2-hydroxyethoxy) benzene and 1,4-bis (2-hydroxyethoxy) benzene. Conductive polymer dispersion.   The conductive polymer dispersion according to claim 1, further comprising a nitrogen-containing aromatic cyclic compound.   The conductive polymer dispersion according to claim 3, wherein the nitrogen-containing aromatic cyclic compound is imidazole.   The conductive polymer dispersion according to any one of claims 1 to 4, further comprising at least one compound having two or more hydroxy groups, which is different from the compound represented by the formula (1).   The conductive polymer dispersion according to any one of claims 1 to 5, wherein the π-conjugated conductive polymer is poly (3,4-ethylenedioxythiophene).   The conductive polymer dispersion according to any one of claims 1 to 6, wherein the polyanion is polystyrene sulfonic acid. 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 opposite side of the dielectric layer from the anode, and the dielectric layer And a solid electrolyte layer formed between the cathodes,
The capacitor in which the solid electrolyte layer includes a conductive complex including a π-conjugated conductive polymer and a polyanion, and a compound represented by the following formula (1).

[In formula (1), m and n each independently represent an integer of 1 to 3, and R ¹ and R ² each independently represent an alkylene group having 2 to 4 carbon atoms. ]   The compound represented by the formula (1) is at least one of 1,3-bis (2-hydroxyethoxy) benzene and 1,4-bis (2-hydroxyethoxy) benzene. Capacitor.   The capacitor according to claim 8 or 9, wherein the solid electrolyte layer further contains a nitrogen-containing aromatic cyclic compound.   The capacitor according to claim 10, wherein the nitrogen-containing aromatic cyclic compound is imidazole.   The capacitor according to any one of claims 8 to 11, wherein the solid electrolyte layer further contains at least one compound having two or more hydroxy groups, which is different from the compound represented by the formula (1).   The capacitor according to claim 8, wherein the π-conjugated conductive polymer is poly (3,4-ethylenedioxythiophene).   The capacitor according to claim 8, wherein the polyanion is polystyrene sulfonic acid. Oxidizing the surface of the anode made of a porous body of valve metal to form a dielectric layer;
Disposing a cathode at a position facing the dielectric layer;
A method of manufacturing a capacitor, comprising: applying a conductive polymer dispersion according to any one of claims 1 to 7 to a surface of the dielectric layer, and drying to form a solid electrolyte layer.

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