JP2019087615A - Capacitor, method for producing the same, and conductive polymer dispersion - Google Patents

Abstract

To provide a capacitor having a smaller equivalent series resistance than before, a method for producing the same, and a conductive polymer dispersion suitable for producing 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 dielectric layer on a side opposite to the anode; and a solid electrolyte layer 14 formed between the dielectric layer and the cathode. The solid electrolyte layer has a conductive complex containing a π-conjugated conductive polymer and a polyanion and one or more compounds selected from a specific compound group.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 of manufacturing the same, and a conductive polymer dispersion.

  In order to reduce the equivalent series resistance of a capacitor, a solid electrolyte layer formed of a conductive polymer dispersion containing poly (3,4-ethylenedioxythiophene) and polystyrene sulfonic acid is used as a dielectric layer and a cathode. A capacitor disposed between the two is known (for example, Patent Document 1).

JP, 2014-67949, A

Conventional capacitors manufactured using a conductive polymer dispersion are required to further reduce their equivalent series resistance.
The present invention provides a capacitor having a smaller equivalent series resistance than before, a method for producing the same, and a conductive polymer dispersion suitable for producing the capacitor.

[1] A conductive polymer dispersion liquid comprising a conductive complex containing a π-conjugated conductive polymer and a polyanion, a nitrogen-containing aromatic compound represented by the following chemical formula (1), and a dispersion medium .
[2] The conductive polymer dispersion liquid according to [1], wherein any organic group of the following chemical formula (1) is an alkyl group, an alkenyl group or an alkynyl group.
[3] The nitrogen-containing aromatic compound represented by the following chemical formula (1) is 1-isobutyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 1-propylimidazole, 1-allylimidazole, and 1- The conductive polymer dispersion according to [1], which is at least one selected from butylimidazole.
[4] The conductive polymer dispersion according to any one of [1] to [3], wherein the π-conjugated conductive polymer is poly (3,4-ethylenedioxythiophene).
[5] The conductive polymer dispersion according to any one of [1] to [4], wherein the polyanion is polystyrene sulfonic acid.
[6] The conductive polymer dispersion according to any one of [1] to [5], wherein the dispersion medium is water.
[7] The conductive polymer dispersion according to any one of [1] to [6], which has a pH of 2.00 to 8.00 at 25 ° C.
[8] An anode comprising a porous body of a valve metal, a dielectric layer comprising an oxide of the valve metal, a cathode made of a conductive material provided on the side of the dielectric layer opposite to the anode, and And a solid electrolyte layer formed between the dielectric layer and the cathode, wherein the solid electrolyte layer is a conductive complex including a π-conjugated conductive polymer and a polyanion, and a surface represented by the following chemical formula (1): And a nitrogen-containing aromatic compound.
[9] The capacitor according to [8], wherein any organic group of the following chemical formula (1) is each independently an alkyl group, an alkenyl group or an alkynyl group.
[10] A nitrogen-containing aromatic compound represented by the following chemical formula (1) is 1-isobutyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 1-propylimidazole, 1-allylimidazole, and 1- The capacitor according to [8], which is at least one selected from butylimidazole.
[11] The capacitor according to any one of [8] to [10], wherein the π-conjugated conductive polymer is poly (3,4-ethylenedioxythiophene).
[12] The capacitor according to any one of [8] to [11], wherein the polyanion is polystyrene sulfonic acid.
[13] A step of oxidizing a surface of an anode made of a porous body of a valve metal to form a dielectric layer, a step of forming a cathode at a position facing the dielectric layer, and a step of forming a dielectric layer A method for producing a capacitor, comprising the steps of applying the conductive polymer dispersion according to any one of [1] to [7] and drying it to form a solid electrolyte layer.

［式中、Ｘ^２及びＸ^３のうち少なくとも一方が窒素原子であり、窒素原子でない場合のＸ^２，Ｘ^３は炭素原子であり、
Ｒ^２は、Ｘ^２が窒素原子である場合は存在せず、
Ｒ^３は、Ｘ^３が窒素原子である場合は存在せず、
Ｒ^１，Ｒ^２，Ｒ^３，Ｒ^４及びＲ^５のうち少なくとも１つは任意の有機基であり、
Ｒ^１，Ｒ^２，Ｒ^３，Ｒ^４及びＲ^５の炭素数の合計が３以上であり、
前記任意の有機基でないＲ^１，Ｒ^２，Ｒ^３，Ｒ^４，Ｒ^５は水素原子である。］

[Wherein, in the case where at least one of X ² and X ³ is a nitrogen atom and it is not a nitrogen atom, X ² and X ³ are carbon atoms,
R ² is absent when X ² is a nitrogen atom,
R ³ is absent when X ³ is a nitrogen atom,
At least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is any organic group,
The total of the carbon number of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is 3 or more,
R ¹ , R ² , R ³ , R ⁴ and R ^{5 which} are not any of the aforementioned organic groups are hydrogen atoms. ]

Since the capacitor of the present invention has a smaller equivalent series resistance than before, it contributes to the enhancement of the performance of electronic devices.
According to the method of manufacturing a capacitor of the present invention, a capacitor having 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 a small equivalent series resistance.

It is a sectional view showing one embodiment of a capacitor of the present invention.

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

Examples of the valve metal constituting the anode 11 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, antimony and the like. Of these, aluminum, tantalum and niobium are preferred.
As a specific example of the anode 11, after etching the aluminum foil to increase the surface area, the surface is oxidized and the sintered body of the tantalum particles and the niobium particles is oxidized and formed into a pellet It can be mentioned. What was treated in this manner is 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 and, for example, anodizes the surface of the anode 11 of a metal body in an electrolytic solution such as an aqueous solution of ammonium adipate. It was formed by Therefore, as shown in FIG. 1, the dielectric layer 12 is also provided with irregularities as in the case of 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 of 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 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 or may not be constant, and may be, for example, a thickness of 1 μm to 100 μm.

  The solid electrolyte layer 14 includes a nitrogen-containing aromatic compound (hereinafter sometimes referred to as a compound (1)) represented by the following chemical formula (1), and a π-conjugated conductive polymer and polyanion described in detail later. And a conductive complex.

［式中、Ｘ^２及びＸ^３のうち少なくとも一方が窒素原子であり、窒素原子でない場合のＸ^２，Ｘ^３は炭素原子であり、
Ｒ^２は、Ｘ^２が窒素原子である場合は存在せず、
Ｒ^３は、Ｘ^３が窒素原子である場合は存在せず、
Ｒ^１，Ｒ^２，Ｒ^３，Ｒ^４及びＲ^５のうち少なくとも１つは任意の有機基であり、
Ｒ^１，Ｒ^２，Ｒ^３，Ｒ^４及びＲ^５の炭素数の合計が３以上であり、
前記任意の有機基でないＲ^１，Ｒ^２，Ｒ^３，Ｒ^４，Ｒ^５は水素原子である。］

[Wherein, in the case where at least one of X ² and X ³ is a nitrogen atom and it is not a nitrogen atom, X ² and X ³ are carbon atoms,
R ² is absent when X ² is a nitrogen atom,
R ³ is absent when X ³ is a nitrogen atom,
At least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is any organic group,
The total of the carbon number of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is 3 or more,
R ¹ , R ² , R ³ , R ⁴ and R ^{5 which} are not any of the aforementioned organic groups are hydrogen atoms. ]

  The compound (1) is preferably one or more selected from the compounds (1-1) to (1-2) represented by the following chemical formulas (1-1) to (1-2).

［各式中、Ｒ^１，Ｒ^２，Ｒ^３，Ｒ^４及びＲ^５のうち少なくとも１つは任意の有機基であり、
Ｒ^１，Ｒ^２，Ｒ^３，Ｒ^４及びＲ^５の炭素数の合計が３以上であり、前記任意の有機基でないＲ^１，Ｒ^２，Ｒ^３，Ｒ^４，Ｒ^５は水素原子である。］

[In each formula, at least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is any organic group,
The total carbon number of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is 3 or more, and R ¹ , R ² , R ³ , R ⁴ and R ^{5 which} are not any of the aforementioned organic groups are hydrogen atoms . ]

In the compound (1) and the compounds (1-1) to (1-3), from the viewpoint of reducing the ESR, it is preferable that the arbitrary organic groups be each independently an alkyl group, an alkenyl group or an alkynyl group.
As said alkyl group, C1-C10 linear or branched alkyl group is mentioned, for example.
As said alkenyl group, C2-C10 linear or branched alkenyl group is mentioned, for example.
As said alkynyl group, C2-C10 linear or branched alkenyl group is mentioned, for example.

  In each compound of compound (1) and compounds (1-1) to (1-3), the total carbon number of all organic groups is preferably 3 or more and 20 or less, more preferably 3 or more and 15 or less, and 3 or more 10 or less is more preferable. When the total number of carbons is 3 or more, the ESR is easily reduced, and when the total number of carbons is 20 or less, the solubility of the compound in the conductive polymer dispersion is increased, and the solid electrolyte is Dispersion of each component is enhanced, and ESR can be easily reduced.

  Among the compounds (1-1) to (1-3), the compound (1-1) and the compound (1-2) are preferable, and the compound (1-1) is more preferable, because the ESR is easily reduced.

Examples of the compound (1-1) include 1-isopropylimidazole, 2-propylimidazole, 2-isopropylimidazole, 2-butylimidazole, 1-isobutyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 1- Propyl imidazole, 1-allyl imidazole, 1-butyl imidazole and the like can be mentioned.
Examples of the solid electrolyte of the capacitor of the present invention include a group of compounds (1-1) exemplified as follows: 1-isobutyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 1-propylimidazole, 1-allylimidazole And one or more selected from 1-butylimidazole is preferably included.

  The content of the exemplified compound (1-1) in the solid electrolyte is preferably as follows with respect to 100 parts by mass of the conductive complex.

  25.0 mass parts or more and 80.0 mass parts or less are preferable, as for the said content of 1-isobutyl -2- methyl imidazole, 30.0 mass parts or more and 60.0 mass parts or less are more preferable, and 35.0 mass parts 55.0 parts by mass or less is more preferable, and 45.0 parts by mass or more and 55.0 parts by mass or less are particularly preferable. Within the above range, the ESR can be reduced and the heat resistance can be improved.

  20.0 mass parts or more and 80.0 mass parts or less are preferable, as for the said content of 2-ethyl -4- methyl imidazole, 25.0 mass parts or more and 70.0 mass parts or less are more preferable, and 30.0 mass parts The content is more preferably 60.0 parts by mass or less and particularly preferably 30.0 parts by mass or more and 50.0 parts by mass or less. Within the above range, the ESR can be reduced and the heat resistance can be improved.

  20.0 mass parts or more and 60.0 mass parts or less are preferable, as for the said content of 1-propyl imidazole, 25.0 mass parts or more and 50.0 mass parts or less are more preferable, and 30.0 mass parts or more and 45.0 mass parts A mass part or less is further preferable, and 32.5 mass parts or more and 40.0 mass parts or less are especially preferable. Within the above range, the ESR can be reduced and the heat resistance can be improved.

  20.0 mass parts or more and 80.0 mass parts or less are preferable, as for the said content of 1-allyl imidazole, 25.0 mass parts or more and 70.0 mass parts or less are more preferable, and 30.0 mass parts or more 60.0 mass parts A mass part or less is further preferable, and 32.5 mass parts or more and 50.0 mass parts or less are especially preferable. Within the above range, the ESR can be reduced and the heat resistance can be improved.

  The content of 1-butylimidazole is preferably 20.0 to 80.0 parts by mass, more preferably 25.0 to 70.0 parts by mass, and 30.0 to 60.0 parts by mass. More preferably, it is 35.0 parts by weight or more and 55.0 parts by weight or less, and most preferably 40.0 parts by weight or more and 50.0 parts by weight or less. Within the above range, the ESR can be reduced and the heat resistance can be improved.

1 mass% or more and 60 mass% or less are preferable, as for content of the sum total of the compound (1) with respect to the total mass of the solid electrolyte layer 14, 10 mass% or more and 50 mass% or less is more preferable, and 25 mass% or more Is more preferred. Within the above range, the equivalent series resistance of the capacitor is more likely to be reduced, which is preferable.
The number of types of the compound (1) contained in the solid electrolyte layer 14 may be one, or two or more.

Next, the conductive complex containing the π-conjugated conductive polymer and the polyanion contained in the solid electrolyte layer 14 will be described.
The π-conjugated conductive polymer is not particularly limited as long as it is an organic polymer having a π-conjugated main chain as its main chain, for example, polypyrrole conductive polymer, polythiophene conductive polymer, polyacetylene type Conductive polymers, polyphenylene-based conductive polymers, polyphenylene vinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophene-vinylene-based conductive polymers, copolymers of these, etc. It can be mentioned. From the viewpoint of stability in air, polypyrrole-based conductive polymers, polythiophene-based conductive polymers, and polyaniline-based conductive polymers are preferable, and polythiophene-based conductive polymers are more preferable.

  Examples of polythiophene-based conductive polymers include polythiophene, poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), poly (3-butylthiophene), 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-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) Ethyl thiophene), poly (3-methyl 4- carboxy butyl thiophene) is mentioned.

  Examples of polypyrrole-based conductive polymers 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 polyaniline-based conductive polymers include polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), poly (2-anilinesulfonic acid) and poly (3-anilinesulfonic acid).
Among the π-conjugated conductive polymers exemplified above, poly (3,4-ethylenedioxythiophene) is particularly preferable in terms of conductivity and heat resistance.
The π conjugated conductive polymers may be used alone or in combination of two or more.

The polyanion is a polymer having two or more monomer units having an anionic group in the molecule. The anion group of this polyanion can function as a dopant for the π conjugated conductive polymer to 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, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly (2-acrylamido-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, and polyisoprene. Polymers having sulfonic acid groups such as sulfoethyl methacrylate, poly (4-sulfobutyl methacrylate), polymethacryloxybenzenesulfonic acid, etc., polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacrylic carboxylic acid, polymethacrylic acid Examples thereof include polymers having a carboxylic acid group such as carboxylic acid, poly (2-acrylamido-2-methylpropane carboxylic acid), polyisoprene carboxylic acid, polyacrylic acid and the like. 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 the conductivity can be further increased.
One type of polyanion may be used alone, or two or more types may be used in combination.
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 in the present specification is a value determined by gel permeation chromatography and using polystyrene as a standard substance.

  The content ratio of the polyanion in the conductive complex is preferably in the range of 1 part by mass or more and 1000 parts by mass or less, and 10 parts by mass or more and 700 parts by mass with respect to 100 parts by mass of the π conjugated conductive polymer. The range is more preferably in the range of 100 parts by mass to 500 parts by mass. If the content of the polyanion is at least the above lower limit, the doping effect on the π-conjugated conductive polymer tends to be strong, sufficient conductivity can be easily obtained, and the conductivity in the conductive polymer dispersion liquid The dispersibility of the complex is increased. Moreover, relative content of (pi) conjugated system conductive polymer increases that content of a polyanion is below the said upper limit, and sufficient conductivity is easy to be obtained.

  A conductive complex is formed by coordination and doping of the polyanion to the π-conjugated conductive polymer. From the viewpoint of improving the conductivity and the dispersibility of the conductive composite, it is preferable that all of the anion groups have an excess of anion groups that do not contribute to doping, rather than being doped to the π-conjugated system conductive polymer.

  40 mass% or more and 99 mass% or less are preferable, as for content of the electroconductive composite body with respect to the total mass of the solid electrolyte layer 14, 50 mass% or more and 90 mass% or less are more preferable, 60 mass% or more and 75 mass% or less preferable. Within the above range, the equivalent series resistance of the capacitor is more likely to be reduced, which is preferable.

  The solid electrolyte layer 14 may contain one or more types of nitrogen-containing compounds other than the compound (1). The inclusion of the nitrogen-containing compound in the solid electrolyte layer 14 can further reduce the equivalent series resistance of the capacitor.

The following amine compounds and nitrogen-containing aromatic cyclic compounds can be exemplified as the nitrogen-containing compounds. When at least one of the amine compound and the nitrogen-containing aromatic cyclic compound 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.
As an amine compound, any of a primary amine, a secondary amine, a tertiary amine, and a quaternary ammonium salt may be used. 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. It may have 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.
Examples of specific primary amines include aniline, toluidine, benzylamine, ethanolamine and the like.
Specific secondary amines include, for example, diethanolamine, dimethylamine, diethylamine, dipropylamine, diphenylamine, dibenzylamine, dinaphthylamine and the like.
Specific tertiary amines include, for example, triethanolamine, trimethylamine, triethylamine, tripropylamine, tributylamine, trioctylamine, triphenylamine, tribenzylamine, trinaphthylamine and the like.
Specific examples of quaternary ammonium salts include tetramethyl ammonium salts, tetraethyl ammonium salts, tetrapropyl ammonium salts, tetraphenyl ammonium salts, tetrabenzyl ammonium salts, tetranaphthyl ammonium salts and the like. The anion which becomes a pair of ammonium includes hydroxide ion.
Among these amine compounds, tertiary amines are preferable, and triethylamine and tripropylamine are more preferable.
Examples of nitrogen-containing aromatic cyclic compounds (aromatic compounds in which at least one nitrogen atom forms a ring structure) include pyrrole, imidazole, 2-methylimidazole, N-methylimidazole, 1- (2-hydroxy) Ethyl) imidazole, 1,2-dimethyl imidazole, pyridine and the like can be mentioned.

The solid electrolyte layer 14 may contain an electrolyte in which an electrolyte is dissolved in a solvent for the electrolyte. The higher the conductivity of the electrolyte, the better.
Examples of the solvent for the electrolytic solution include alcohol solvents such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol and glycerin, lactone solvents such as γ-butyrolactone, γ-valerolactone and δ-valerolactone, Amide solvents such as N-methylformamide, N, N-dimethylformamide, N-methylacetamide, N-methylpyrrolidinone and the like, acetonitrile, nitrile solvents such as 3-methoxypropionitrile, water and the like.
As the electrolyte, for example, adipic acid, glutaric acid, succinic acid, benzoic acid, isophthalic acid, phthalic acid, terephthalic acid, maleic acid, toluic acid, enanthate, malonic acid, formic acid, 1,6-decanedicarboxylic acid, 5 Decanedicarboxylic acids such as 1,6-decanedicarboxylic acid, octanedicarboxylic acids such as 1,7-octanedicarboxylic acid, organic acids such as azelaic acid and sebacic acid; or boric acid obtained from boric acid and boric acid and polyhydric alcohol Inorganic compounds such as phosphoric acid, carbonic acid and silicic acid as an anion component, primary amines (methylamine, ethylamine, propylamine, butylamine, ethylenediamine etc.), secondary amines (dimethylamine, diethylamine, diamine) Propylamine, methylethylamine, diphenylamine etc., tertiary amine ( Lymethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo (5,4,0) -undecene-7, etc., tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, Electrolyte which made methyl triethyl ammonium, dimethyl diethyl ammonium etc. etc. the cation component; etc. are mentioned.

<Function effect>
When the solid electrolyte layer of the capacitor of the present invention contains the compound (1), the equivalent series resistance of the capacitor can be reduced as compared to the conventional one without lowering the capacitance. Although this mechanism is not elucidated, the compound (1) in which the total carbon number of substituents is 3 or more and a relatively large number of carbon atoms exist around the 5-membered ring improves the conductivity of the solid electrolyte layer It is presumed that the equivalent series resistance is reduced by

<< Production Method of Capacitor, Conductive Polymer Dispersion >>
In the capacitor according to the present invention, a step of oxidizing the surface of an anode made of a porous body of a valve metal to form a dielectric layer (a dielectric forming step), and disposing a cathode at a position facing the dielectric layer A conductive polymer dispersion can be applied to at least a part of the surface of the dielectric layer and dried to form a solid electrolyte layer.

The conductive polymer dispersion is a dispersion in which a conductive complex containing a π-conjugated conductive polymer and a polyanion is dispersed, containing one or more kinds of the compound (1).
The conductive polymer dispersion may contain a nitrogen-containing compound other than the compound (1) described above, an additive described later, and the like.

The dielectric layer forming step is a step of oxidizing the surface of the anode 11 made of a porous body of valve metal to form the dielectric layer 12.
The dielectric layer 12 may be formed by, for example, anodizing the surface of the anode 11 in a chemical conversion electrolytic solution 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 arranging the cathode 13 at a position facing the dielectric layer 12.
As a method of arranging the cathode 13, for example, a method of forming the cathode 13 using a conductive paste such as a carbon paste or a silver paste, a method of arranging a metal foil such as an aluminum foil opposite to the dielectric layer 12, etc. Be

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

The dispersion medium constituting the conductive polymer dispersion is not particularly limited as long as it is a liquid capable of dispersing the conductive complex, and, for example, water, an organic solvent, or a liquid mixture of water and an organic solvent may be mentioned. Be
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 alone or in combination of two or more.
Examples of alcohol solvents include methanol, ethanol, isopropanol, n-butanol, t-butanol, allyl alcohol and the like.
Examples of the ether solvents include propylene glycol monoalkyl ethers such as diethyl ether, dimethyl ether, ethylene glycol, propylene glycol and propylene glycol monomethyl ether, and propylene glycol dialkyl ether.
Examples of the ketone solvents include diethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisopropyl ketone, methyl ethyl ketone, acetone, diacetone alcohol and the like.
Examples of the ester solvents 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.

As an additive, surfactant, an inorganic electrically conductive agent, an antifoamer, a coupling agent, an antioxidant, an ultraviolet absorber, a highly conductive agent etc. are mentioned, for example. However, the additive is a compound other than the conductive complex, the compound (1) and the nitrogen-containing compound.
Examples of the surfactant include nonionic, anionic and cationic surfactants. From the viewpoint of storage stability, nonionic surfactants are preferable. In addition, a polymer surfactant such as polyvinyl alcohol or polyvinyl pyrrolidone may be added.
Examples of the inorganic conductive agent include metal ions and conductive carbon. Metal ions can be generated by dissolving metal salts in water.
As an antifoamer, silicone resin, polydimethylsiloxane, silicone oil etc. are mentioned.
As a coupling agent, the silane coupling agent etc. which have a vinyl group, an amino group, an epoxy group etc. are mentioned.
Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, saccharides and the like.
Examples of UV absorbers include benzotriazole UV absorbers, benzophenone UV absorbers, salicylate UV absorbers, cyanoacrylate UV absorbers, oxanilide UV absorbers, hindered amine UV absorbers, benzoate UV absorbers, etc. Can be mentioned.
The high conductivity agent can improve the conductivity of the conductive complex and contribute to lowering the ESR. As the high conductivity agent, saccharides, compounds having two or more hydroxy groups, compounds having one or more hydroxy groups and one or more carboxy groups, compounds having an amide group, compounds having an imide group, lactam compounds And compounds having a glycidyl group.
When the conductive polymer dispersion forming the solid electrolyte layer contains a component other than the conductive complex and the compound (1) such as the above-mentioned additives, the component may be contained in the solid electrolyte layer.

  The content of the conductive complex with respect to the total mass of the conductive polymer dispersion is not particularly limited, and is preferably such a content that makes it easy to apply. Specifically, for example, 0.1% by mass or more and 10% by mass or less is preferable, 0.5% by mass or more and 5% by mass or less is more preferable, and 1% by mass or more and 2% by mass or less is more preferable.

  The total content of one or more of the compound (1) relative to the total mass of the conductive polymer dispersion is not particularly limited, and is preferably such a content that makes it easy to apply. Specifically, for example, 0.1% by mass or more and 2.0% by mass or less is preferable, 0.2% by mass or more and 1.0% by mass or less is more preferable, and 0.3% by mass or more and 0.8% by mass or less Is more preferred.

  When the conductive polymer dispersion liquid contains the nitrogen-containing compound other than the compound (1), the content ratio may be appropriately determined according to the type of the nitrogen-containing compound. For example, the solid content of the conductive complex is 100 1 mass part or more and 100 mass parts or less are preferable with respect to a mass part, for example, 10 mass parts or more and 50 mass parts or less are more preferable.

  When the conductive polymer dispersion contains the additive, the content ratio thereof is appropriately determined according to the type of the additive, and for example, with respect to 100 parts by mass of the solid content of the conductive composite, for example, It can be in the range of 1 part by mass or more and 1000 parts by mass or less.

As a method of preparing the conductive polymer dispersion, a method of oxidatively polymerizing a precursor monomer forming a π-conjugated conductive polymer in the presence of a polyanion and a dispersion medium can be mentioned.
One or more types of compounds (1) can be added to the obtained conductive polymer dispersion, and the above-mentioned nitrogen-containing compounds other than the compound (1), additives, etc. can be added, if necessary.
In order to improve the dispersibility of each material contained in the conductive polymer dispersion, it is preferable to carry out a known high dispersion treatment in which the conductive polymer dispersion is dispersed while applying a shearing force before coating.

2.00 or more and 8.00 or less are preferable, and, as for the pH in 25 degreeC of the conductive polymer dispersion liquid containing 1 or more types of a compound (1), 2.50 or more and 7.50 or less are more preferable, and 3.00 or more 7.00 or less is further preferable, and 3.50 or more and 7.00 or less are especially preferable.
When the pH is in the above range, the ESR of the capacitor can be further reduced.
The measurement of the pH of the conductive polymer dispersion is carried out with a known pH measuring device in accordance with JIS Z 8802: 2011.

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

The capacitor of the present invention and the method of manufacturing the same are not limited to the examples of the above embodiments.
In the capacitor of the present invention, a separator may be provided between the dielectric layer and the cathode.
Examples of capacitors provided with a separator between the dielectric layer and the cathode include wound capacitors.
Examples of the separator include sheets (including nonwoven fabrics) made of cellulose, polyvinyl alcohol, polyester, polyethylene, polystyrene, polypropylene, polyimide, polyamide, polyvinylidene fluoride and the like, and nonwoven fabrics of glass fibers.
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.
When providing a separator, the method of impregnating a separator with carbon paste or silver paste, and forming a cathode can also be applied.

(Production Example 1)
Dissolve 206 g of sodium styrene sulfonate in 1000 ml of ion-exchanged water and add 1.14 g of ammonium persulfate oxidizing agent solution previously dissolved in 10 ml of water for 20 minutes while stirring at 80 ° C. for 20 minutes. It stirred.
1000 ml of sulfuric acid diluted to 10% by mass was added to the obtained sodium styrenesulfonate-containing solution, and about 1000 ml of a solvent of the polystyrenesulfonic acid-containing solution was removed by ultrafiltration. To the residue, 2000 ml of ion exchanged water was added, about 2000 ml of the solvent was removed by ultrafiltration, and the polystyrenesulfonic 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 of 14.2 g of 3,4-ethylenedioxythiophene and 36.7 g of polystyrene sulfonic acid obtained in Production Example 1 dissolved in 2000 ml of ion-exchanged water was mixed at 20 ° C.
The obtained mixed solution is kept at 20 ° C., and 29.64 g of ammonium persulfate dissolved in 200 ml of ion exchanged water and 8.0 g of a ferric sulfate oxidation catalyst solution are slowly added while stirring, for 3 hours The reaction was allowed to stir.
2000 ml of ion exchange water was added to the obtained reaction solution, and about 2000 ml solution was removed by ultrafiltration. This operation was repeated three times.
200 ml of sulfuric acid diluted to 10% by mass and 2000 ml of deionized water were added to the obtained solution, and about 2000 ml of solvent was removed by ultrafiltration. To the residue, 2000 ml of ion exchanged water was added, about 2000 ml of the solvent was removed by ultrafiltration, and the polystyrene sulfonate-doped poly (3,4-ethylenedioxythiophene) (PEDOT-PSS) was washed with water. This operation was repeated eight times to obtain 1.60% by mass of a polystyrene sulfonic 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 is applied in a 10% by mass aqueous solution of ammonium adipate to form (oxidize), and dielectric layers are formed on both sides of the aluminum foil. It formed and obtained anode foil.
Next, opposing aluminum cathode foils having cathode lead terminals welded on both sides of the anode foil were laminated via a cellulose separator, and this was cylindrically wound to obtain a capacitor element.

Example 1
In 100 parts by mass of a 1.60% by mass PEDOT-PSS aqueous dispersion obtained in Production Example 2, 0.407 parts by mass of 1-isobutyl-2-methylimidazole represented by the following formula (a) (conductive complex 25.4 parts by mass) was added to 100 parts by mass, and the mixture was stirred at room temperature and then subjected to dispersion treatment at a pressure of 100 MPa using a high pressure dispersion machine to obtain a conductive polymer dispersion. The pH of the conductive polymer dispersion at 25 ° C. was measured by a pH meter to be 2.06.
The element for a capacitor obtained in Production Example 3 is immersed in a conductive polymer dispersion under reduced pressure and then dried for 30 minutes with a hot air drier at 125 ° C. twice to repeat conductivity on the surface of the dielectric layer. A solid electrolyte layer containing the complex was formed.
Subsequently, the element for capacitors which formed the solid electrolyte layer in the case made from aluminum was loaded, and it sealed with sealing rubber, and obtained the capacitor.
(Example 2)
A capacitor was obtained in the same manner as in Example 1 except that the addition amount of 1-isobutyl-2-methylimidazole was changed to 0.625 parts by mass (39.1 parts by mass with respect to 100 parts by mass of the conductive complex). .
(Example 3)
A capacitor was obtained in the same manner as in Example 1 except that the addition amount of 1-isobutyl-2-methylimidazole was changed to 0.702 parts by mass (43.8 parts by mass with respect to 100 parts by mass of the conductive complex). .
(Example 4)
A capacitor was obtained in the same manner as in Example 1 except that the addition amount of 1-isobutyl-2-methylimidazole was changed to 0.804 parts by mass (50.2 parts by mass with respect to 100 parts by mass of the conductive complex). .
(Example 5)
A capacitor was obtained in the same manner as in Example 1 except that the addition amount of 1-isobutyl-2-methylimidazole was changed to 0.901 parts by mass (56.3 parts by mass with respect to 100 parts by mass of the conductive complex). .

(Example 6)
1-isobutyl-2-methylimidazole is changed to 2-ethyl-4-methylimidazole represented by the following formula (b), and the addition amount thereof is 0.375 parts by mass (based on 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as in Example 1 except that it was changed to 23.4 parts by mass.
(Example 7)
1-isobutyl-2-methylimidazole was changed to 2-ethyl-4-methylimidazole, and the addition amount was changed to 0.487 parts by mass (30.4 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as Example 1 except for the above.

(Example 8)
1-isobutyl-2-methylimidazole is changed to 1-propylimidazole represented by the following formula (c), and the addition amount thereof is 0.490 parts by mass (30.6 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as in Example 1 except that it was changed to
(Example 9)
Example except that 1-isobutyl-2-methylimidazole was changed to 1-propylimidazole and the addition amount was changed to 0.554 parts by mass (34.6 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as 1.

(Example 10)
1-isobutyl-2-methylimidazole is changed to 1-allylimidazole represented by the following formula (d), and the addition amount thereof is 0.416 parts by mass (26.0 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as in Example 1 except that it was changed to
(Example 11)
Example except that 1-isobutyl-2-methylimidazole was changed to 1-allylimidazole, and the addition amount thereof was changed to 0.557 parts by mass (34.8 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as 1.

(Example 12)
1-isobutyl-2-methylimidazole is changed to 1-butylimidazole represented by the following formula (e), and the addition amount thereof is 0.382 parts by mass (23.9 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as in Example 1 except that it was changed to
(Example 13)
Example except that 1-isobutyl-2-methylimidazole was changed to 1-butylimidazole and the addition amount was changed to 0.505 mass parts (31.6 mass parts with respect to 100 mass parts of conductive composites) A capacitor was obtained in the same manner as 1.
(Example 14)
Example except that 1-isobutyl-2-methylimidazole was changed to 1-butylimidazole and the addition amount was changed to 0.752 parts by mass (47.0 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as 1.

(Comparative example 1)
1-isobutyl -2- methyl imidazole is changed into the imidazole represented by the following formula (f), and the addition amount is 0.223 mass parts (13.9 mass parts with respect to 100 mass parts of electroconductive complexes) A capacitor was obtained in the same manner as in Example 1 except for the change.
(Comparative example 2)
The same as Example 1 except that 1-isobutyl-2-methylimidazole was changed to imidazole and the addition amount was changed to 0.255 parts by mass (15.9 parts by mass with respect to 100 parts by mass of the conductive composite) I got a capacitor.
(Comparative example 3)
Example 1 is similar to Example 1 except that 1-isobutyl-2-methylimidazole is changed to imidazole, and the addition amount is changed to 0.300 parts by mass (18.8 parts by mass with respect to 100 parts by mass of the conductive complex) I got a capacitor.
(Comparative example 4)
The same as Example 1 except that 1-isobutyl-2-methylimidazole was changed to imidazole, and the addition amount was changed to 0.350 parts by mass (21.9 parts by mass with respect to 100 parts by mass of the conductive composite) I got a capacitor.
(Comparative example 5)
The same as Example 1 except that 1-isobutyl-2-methylimidazole was changed to imidazole and the addition amount was changed to 0.475 parts by mass (29.7 parts by mass with respect to 100 parts by mass of the conductive composite) I got a capacitor.

(Comparative example 6)
1-isobutyl-2-methylimidazole is changed to 1-vinylimidazole represented by the following formula (g), and the addition amount thereof is 0.390 parts by mass (24.4 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as in Example 1 except that it was changed to
(Comparative example 7)
Example except that 1-isobutyl-2-methylimidazole was changed to 1-vinylimidazole, and the addition amount was changed to 0.589 parts by mass (36.8 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as 1.

(Comparative example 8)
1-isobutyl-2-methylimidazole is changed to 1-methylimidazole represented by the following formula (h), and the addition amount thereof is 0.364 parts by mass (22.8 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as in Example 1 except that it was changed to
(Comparative example 9)
Example except that 1-isobutyl-2-methylimidazole was changed to 1-methylimidazole, and the addition amount thereof was changed to 0.582 parts by mass (36.4 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as 1.

(Comparative example 10)
1-isobutyl-2-methylimidazole is changed to 2-ethylimidazole represented by the following formula (i), and the addition amount thereof is 0.561 parts by mass (35.0 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as in Example 1 except that it was changed to

(Comparative example 11)
1-isobutyl-2-methylimidazole is changed to 1,2-dimethylimidazole represented by the following formula (j), and the addition amount thereof is 0.408 parts by mass (25. 25 parts by mass with respect to 100 parts by mass of the conductive complex). A capacitor was obtained in the same manner as in Example 1 except that the amount was changed to 5 parts by mass.
(Comparative example 12)
1-isobutyl-2-methylimidazole was changed to 1,2-dimethylimidazole, and the addition amount thereof was changed to 0.604 parts by mass (37.7 parts by mass with respect to 100 parts by mass of the conductive complex) A capacitor was obtained in the same manner as in Example 1.

[Evaluation]
[Capacitance, equivalent series resistance]
The capacitor of Examples 1 to 14 and Comparative Examples 1 to 12, using an LCR meter ZM2376 ((KK) NF circuit design block), the electrostatic capacity at 120 Hz _(C 0), and equivalent series resistance at 100kHz The (ESR ₀ ) was measured. The measurement results are shown in Table 1.

[Heat resistance test]
The capacitors of Examples 1 to 14 and Comparative Examples 1 to 12 were allowed to stand in a hot air dryer at 135 ° C., taken out after 1000 hours, and cooled at room temperature for 30 minutes. The capacitance after cooling (C ₁ ) at 120 Hz and the equivalent series resistance (ESR ₁ ) at 100 kHz were measured using a LCR meter ZM2376 (manufactured by NFU Circuit Design Block) for the capacitor after cooling. 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. The ΔC and ΔESR are also shown in Table 1.

The above chemical formulas represent the compounds used in the examples and the compounds used in the comparative examples.
The capacitors produced in Examples 1 to 14 had sufficient capacitance and low equivalent series resistance. Furthermore, the equivalent series resistance after the heat resistance test was also low.
The capacitors manufactured in Comparative Examples 1 to 12 have sufficient capacitance but high equivalent series resistance. Furthermore, the equivalent series resistance after the heat resistance test was also high.

10 capacitor 11 anode 12 dielectric layer 13 cathode 14 solid electrolyte layer

Claims (13)

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

[Wherein, in the case where at least one of X ² and X ³ is a nitrogen atom and it is not a nitrogen atom, X ² and X ³ are carbon atoms,
R ² is absent when X ² is a nitrogen atom,
R ³ is absent when X ³ is a nitrogen atom,
At least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is any organic group,
The total of the carbon number of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is 3 or more,
R ¹ , R ² , R ³ , R ⁴ and R ^{5 which} are not any of the aforementioned organic groups are hydrogen atoms. ]   The conductive polymer dispersion according to claim 1, wherein the optional organic group is an alkyl group, an alkenyl group or an alkynyl group.   The nitrogen-containing aromatic compound represented by the chemical formula (1) is selected from 1-isobutyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 1-propylimidazole, 1-allylimidazole, and 1-butylimidazole The conductive polymer dispersion according to claim 1, which is at least one selected.   The conductive polymer dispersion according to any one of claims 1 to 3, wherein the π-conjugated conductive polymer is poly (3,4-ethylenedioxythiophene).   The conductive polymer dispersion according to any one of claims 1 to 4, wherein the polyanion is polystyrene sulfonic acid.   The conductive polymer dispersion according to any one of claims 1 to 5, wherein the dispersion medium is water.   The conductive polymer dispersion according to any one of claims 1 to 6, wherein the pH at 25 ° C is 2.00 or more and 8.00 or less. An anode comprising a porous body of a valve metal, a dielectric layer comprising an oxide of the valve metal, a cathode made of a conductive material provided on the opposite side of the dielectric layer, the dielectric layer And a solid electrolyte layer formed between the cathodes,
A capacitor, wherein the solid electrolyte layer comprises a conductive complex containing a π-conjugated conductive polymer and a polyanion, and a nitrogen-containing aromatic compound represented by the following chemical formula (1).

[Wherein, in the case where at least one of X ² and X ³ is a nitrogen atom and it is not a nitrogen atom, X ² and X ³ are carbon atoms,
R ² is absent when X ² is a nitrogen atom,
R ³ is absent when X ³ is a nitrogen atom,
At least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is any organic group,
The total of the carbon number of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is 3 or more,
R ¹ , R ² , R ³ , R ⁴ and R ^{5 which} are not any of the aforementioned organic groups are hydrogen atoms. ]   The capacitor according to claim 8, wherein the arbitrary organic groups are each independently an alkyl group, an alkenyl group or an alkynyl group.   The nitrogen-containing aromatic compound represented by the chemical formula (1) is selected from 1-isobutyl-2-methylimidazole, 2-ethyl-4-methylimidazole, 1-propylimidazole, 1-allylimidazole, and 1-butylimidazole The capacitor according to claim 8, which is at least one selected.   The capacitor according to any one of claims 8 to 10, wherein the π-conjugated conductive polymer is poly (3,4-ethylenedioxythiophene).   The capacitor according to any one of claims 8 to 11, 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;
Forming a cathode at a position facing the dielectric layer;
A method of manufacturing a capacitor, comprising the steps of applying the conductive polymer dispersion according to any one of claims 1 to 7 on the surface of the dielectric layer and drying it to form a solid electrolyte layer.

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