JP7241658B2 - Capacitor, manufacturing method thereof, and conductive polymer dispersion - Google Patents

Description

TECHNICAL FIELD The present invention relates to a capacitor having a solid electrolyte layer containing a π-conjugated conductive polymer, a method for producing 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 placed between the dielectric layer and the cathode. A capacitor arranged in between is known (eg, Patent Document 1).

JP 2014-67949 A

Conventional capacitors manufactured using conductive polymer dispersions are required to have a reduced equivalent series resistance. Further, it is desired to improve the heat resistance of the capacitor.
The present invention provides a capacitor having a lower equivalent series resistance and excellent heat resistance than conventional capacitors, a method for producing the same, and a conductive polymer dispersion suitable for producing the capacitor.

[1] A conductive polymer dispersion containing a conductive composite containing a π-conjugated conductive polymer and a polyanion, at least one compound represented by the following formula (1), and a dispersion medium.
[2] The conductive polymer dispersion according to [1], containing a compound represented by the following formula (1), wherein at least one R is a methoxy group.
[3] The conductive polymer dispersion according to [1], which contains guaiacol glycerol ether, which is a compound represented by the following formula (1).
[4] The conductive polymer dispersion according to any one of [1] to [3], further containing at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine.
[5] The conductive polymer dispersion according to [4], which contains imidazole, which is the nitrogen-containing aromatic cyclic compound.
[6] The conductive polymer dispersion according to [4], containing triethylamine as the tertiary amine.
[7] The conductive polymer dispersion according to any one of [1] to [6], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene).
[8] The conductive polymer dispersion according to any one of [1] to [7], wherein the polyanion is polystyrenesulfonic acid.
[9] an anode made of a porous material 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 side of the dielectric layer opposite to the anode; A dielectric layer and a solid electrolyte layer formed between the cathode, wherein the solid electrolyte layer comprises a conductive composite containing a π-conjugated conductive polymer and a polyanion, and a compound represented by the following formula (1): and at least one compound comprising:
[10] The capacitor according to [9], wherein the solid electrolyte layer contains the compound represented by the formula (1), wherein at least one R is a methoxy group.
[11] The capacitor according to [10], wherein the solid electrolyte layer contains guaiacol glycerol ether, which is the compound represented by formula (1).
[12] The capacitor according to any one of [9] to [11], wherein the solid electrolyte layer further contains at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine.
[13] The capacitor according to [12], wherein the solid electrolyte layer contains imidazole, which is the nitrogen-containing aromatic cyclic compound.
[14] The capacitor according to [12], wherein the solid electrolyte layer contains triethylamine, which is the tertiary amine.
[15] The capacitor according to any one of [9] to [14], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene).
[16] The capacitor according to any one of [9] to [15], wherein the polyanion is polystyrenesulfonic acid.
[17] oxidizing the surface of an anode made of a porous material of a valve metal to form a dielectric layer; disposing a cathode at a position facing the dielectric layer; A method for producing a capacitor, comprising a step of applying the conductive polymer dispersion according to any one of [1] to [8] and drying it to form a solid electrolyte layer.

［式（１）中、Ｒは水素原子または任意の置換基を表し、ｍは１～５の整数を表す。］

[In formula (1), R represents a hydrogen atom or an arbitrary substituent, and m represents an integer of 1 to 5. ]

Since the capacitor of the present invention has a lower equivalent series resistance than conventional capacitors and is excellent in heat resistance, it contributes to improving the performance of electronic devices. According to the capacitor manufacturing method of the present invention, the above capacitor can be manufactured easily. The conductive polymer dispersion of the present invention is suitable for forming the solid electrolyte layer of the capacitor.

1 is a cross-sectional view showing one embodiment of a capacitor of the present invention; FIG.

《Capacitor》
An embodiment of the capacitor of the present invention will be described. As shown in FIG. 1, a capacitor 10 of this embodiment includes an anode 11 made of a porous valve metal material, a dielectric layer 12 made of an oxide of the valve metal, and a dielectric layer 12 formed on the surface of the dielectric layer 12. It has a solid electrolyte layer 14 and a cathode 13 provided on the frontmost side. Cathode 13 is provided on the opposite side of anode 11 with dielectric layer 12 and solid electrolyte layer 14 interposed therebetween.

Examples of valve metals forming the anode 11 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Among these, aluminum, tantalum and niobium are preferred.
As a specific example of the anode 11, after etching an aluminum foil to increase the surface area, the surface is oxidized, or the surface of a sintered body of tantalum particles or niobium particles is oxidized and made into pellets. mentioned. The material treated in this way becomes a porous body having irregularities formed on the surface.

The dielectric layer 12 in this embodiment is a layer formed by oxidizing the surface of the anode 11. For example, the surface of the metal anode 11 is anodized 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 formed with irregularities in the same manner as the anode 11 .

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

The solid electrolyte layer 14 in this embodiment is formed on the surface of the dielectric layer 12 . Solid electrolyte layer 14 covers at least part of the surface of dielectric layer 12 , and may cover the entire surface of dielectric layer 12 .
The thickness of the solid electrolyte layer 14 may or may not be constant, and may be, for example, 1 μm or more and 100 μm or less.

The solid electrolyte layer 14 contains 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, which will be described in detail later. and a conductive composite.

［式（１）中、Ｒは水素原子または任意の置換基を表し、ｍは１～５の整数を表す。］

[In formula (1), R represents a hydrogen atom or an arbitrary substituent, and m represents an integer of 1 to 5. ]

In the above formula (1), m is an integer of 1-5. When R is other than a hydrogen atom, m is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1, from the viewpoint of further exhibiting the effects of the present invention. When m is 2 or more, multiple R's may be the same or different.

Examples of optional substituents other than the hydrogen atom represented by R in the formula (1) include a hydroxy group, a linear or branched alkyl group having 1 to 14 carbon atoms (e.g., methyl group, ethyl propyl group, butyl group, etc.), alicyclic alkyl groups having 5 to 10 carbon atoms (e.g., cyclopentane, cyclohexane, cycloheptane, etc.), alkoxy groups having 1 to 14 carbon atoms (e.g., methoxy group, ethoxy group , propoxy group, butoxy group, etc.), aryl groups having 6 to 14 carbon atoms (eg, phenyl group, etc.), and the like.
The optional substituent other than the hydrogen atom represented by R is preferably the alkyl group or the alkoxy group, more preferably an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. An alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 2 carbon atoms is more preferable.

When R is an alkyl group or an alkoxy group, m is preferably 1 or 2, more preferably 1. When the R is an alkyl group or an alkoxy group and m is 2 or more, the multiple Rs may be the same or different.
In the above formula (1), when the R is an alkyl group or an alkoxy group, the carbon atom of the benzene ring to which the oxygen atom of the ether group to which the carbon atom at the 3-position of 1,2-propanediol is bonded is at the 1-position. When the R is preferably bonded to the carbon atom at the 2-position (ortho-position) or the carbon atom at the 3-position (meta-position) adjacent to the carbon atom at the 1-position, the carbon atom at the ortho-position More preferably, the Rs are bonded.

Among the compounds represented by the formula (1), guaiacol glycerol ether represented by the following formula (1A) and mephenesine represented by the following formula (1B) are particularly preferable.

The total content of the compound 1 contained in the solid electrolyte layer 14 is preferably 10 parts by mass or more and 1000 parts by mass or less, and 20 parts by mass with respect to 100 parts by mass of the conductive composite described later contained in the solid electrolyte layer 14. 600 parts by mass or less is more preferable, 30 parts by mass or more and 500 parts by mass or less is more preferable, 40 parts by mass or more and 400 parts by mass or less is particularly preferable, and 50 parts by mass or more and 200 parts by mass or less is most preferable.
Within the above range, the equivalent series resistance of the capacitor can be more easily reduced, and the heat resistance can be more easily improved, which is preferable.
The number of types of compound 1 contained in solid electrolyte layer 14 may be one, or two or more.

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 it is an organic polymer having a π-conjugated main chain. Examples include polypyrrole-based conductive polymers, polythiophene-based conductive polymers, and polyacetylene-based Conductive polymers, polyphenylene-based conductive polymers, polyphenylene vinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophene-vinylene-based conductive polymers, and copolymers thereof mentioned. From the viewpoint of stability in air, a polypyrrole-based conductive polymer, a polythiophene-based conductive polymer, and a polyaniline-based conductive polymer are preferable, and a polythiophene-based conductive polymer is more preferable.

Polythiophene-based conductive polymers include, for example, 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-heptyloxy thiophene), 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-dihexyloxy thiophene), poly(3,4-diheptyloxythiophene), poly(3,4-dioctyloxythiophene), poly(3,4-didecyloxythiophene), poly(3,4-didodecyloxythiophene), Poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), poly(3,4-butylenedioxythiophene), poly(3-methyl-4-methoxythiophene), poly( 3-methyl-4-ethoxythiophene), poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), poly(3-methyl-4 -carboxybutylthiophene).

Polypyrrole-based conductive polymers include, for example, polypyrrole, poly(N-methylpyrrole), poly(3-methylpyrrole), poly(3-ethylpyrrole), poly(3-n-propylpyrrole), poly(3 -butylpyrrole), poly(3-octylpyrrole), poly(3-decylpyrrole), poly(3-dodecylpyrrole), poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole), poly (3-carboxypyrrole), poly(3-methyl-4-carboxypyrrole), poly(3-methyl-4-carboxyethylpyrrole), poly(3-methyl-4-carboxybutylpyrrole), poly(3-hydroxy pyrrole), poly(3-methoxypyrrole), poly(3-ethoxypyrrole), poly(3-butoxypyrrole), poly(3-hexyloxypyrrole), poly(3-methyl-4-hexyloxypyrrole) be done.

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 polymer may be used alone or in combination of two or more.

A polyanion is a polymer having two or more monomer units having an anionic group in its molecule. The anion group of this polyanion functions as a dopant for the π-conjugated conductive polymer, and can improve the conductivity of the π-conjugated conductive polymer.
The anionic group of the polyanion is preferably a sulfo group or a carboxy group.
Specific examples of polyanions include polystyrenesulfonic acid, polyvinylsulfonic acid, polyallylsulfonic acid, polyacrylic acid esters having a sulfo group, and polymethacrylic acid esters having a sulfo group (e.g., poly(4-sulfobutyl methacrylate, polysulfo Ethyl methacrylate, polymethacryloyloxybenzenesulfonic acid), poly(2-acrylamido-2-methylpropanesulfonic acid), polymers having a sulfo group such as polyisoprene sulfonic acid, polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid Polymers having a carboxy group such as acid, polyacrylic acid, polymethacrylic acid, poly(2-acrylamido-2-methylpropanecarboxylic acid), polyisoprenecarboxylic acid, etc. These homopolymers may also be used. However, it may be a copolymer of two or more kinds.
Among these polyanions, a polymer having a sulfo group is preferable, and polystyrene sulfonic acid is more preferable, because the conductivity can be further increased.
One of the polyanions may be used alone, or two or more thereof may be used in combination.
The weight average molecular weight of the polyanion is preferably 20,000 or more and 1,000,000 or less, more preferably 100,000 or more and 500,000 or less.
The mass average molecular weight of polyanion is a value obtained by measuring by gel permeation chromatography and using polystyrene as a standard substance.

The content of the polyanion in the conductive composite 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 following range is more preferable, and the range of 100 parts by mass or more and 500 parts by mass or less is even more preferable. When 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, and sufficient conductivity is likely to be obtained. The dispersibility of the composite is increased. Moreover, when the content of the polyanion is equal to or less than the above upper limit, the relative content of the π-conjugated conductive polymer increases, and sufficient conductivity is easily obtained.

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

The content of the conductive composite with respect to the total mass of the solid electrolyte layer 14 is preferably 1% by mass or more and 99% by mass or less, more preferably 50% by mass or more and 98% by mass or less, and further 70% by mass or more and 97% by mass or less. preferable. Within the above range, the equivalent series resistance of the capacitor is more likely to decrease, which is preferable.

The solid electrolyte layer 14 preferably contains 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 can be further reduced.
An amine compound is a compound having an amino group, and the amino group reacts with an anion group of a 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, and an alkylene group having 2 to 12 carbon atoms. , 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 primary amines include, for example, 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, and trinaphthylamine.
Specific quaternary ammonium salts include, for example, tetramethylammonium salts, tetraethylammonium salts, tetrapropylammonium salts, tetraphenylammonium salts, tetrabenzylammonium salts, tetranaphthylammonium salts and the like. A hydroxide ion is mentioned as an anion which becomes a pair with ammonium.
Among these amine compounds, tertiary amines are preferred, and triethylamine and tripropylamine are more preferred.
Nitrogen-containing aromatic cyclic compounds (aromatic compounds in which at least one nitrogen atom forms a ring structure) include, for example, pyrrole, imidazole, 2-methylimidazole, 2-propylimidazole, N-methylimidazole, N -propylimidazole, N-butylimidazole, 1-(2-hydroxyethyl)imidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2- methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 1-acetylimidazole, 2-aminobenzimidazole, 2-amino-1-methylbenzimidazole, 2 -hydroxybenzimidazole, 2-(2-pyridyl)benzimidazole, pyridine and the like.
Among 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 0.1 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the conductive composite contained in the solid electrolyte layer 14. It is more preferably 5 parts by mass or more and 100 parts by mass or less, even more preferably 5 parts by mass or more and 50 parts by mass or less, and particularly preferably 10 parts by mass or more and 30 parts by mass or less.
Within the above range, the equivalent series resistance of the capacitor can be more easily reduced, and the heat resistance can be more easily improved, which is preferable.
The type of the nitrogen-containing compound contained in the solid electrolyte layer 14 may be one type, or two or more types.

The solid electrolyte layer 14 contains at least one compound having two or more hydroxy groups (hereinafter sometimes referred to as a polyol compound) different from the compound 1, the conductive composite, and the nitrogen-containing compound. It may also be included. By containing the polyol compound, the ESR of the capacitor can be further reduced.
Examples of the polyol compound include one or more selected from ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, glycerin, pentaerythritol, trimethylolpropane and trimethylolethane.
The polyol compound may be contained as a solvent for an electrolyte or a dispersion medium for a conductive composite, which will be described later.

The total content of the polyol compounds contained in the solid electrolyte layer 14 is preferably 100 parts by mass or more and 10000 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 parts by mass or less is more preferable, and 300 parts by mass or more and 1000 parts by mass or less is even more preferable.
Within the above range, the equivalent series resistance of the capacitor can be more easily reduced, and the heat resistance can be more easily improved, which is preferable.
The number of types of the polyol compound contained in the solid electrolyte layer 14 may be one, or two or more.

The solid electrolyte layer 14 may contain an electrolytic solution in which an electrolyte is dissolved in an electrolytic solution solvent. The higher the electrical conductivity of the electrolytic solution, the better.
Solvents for electrolytic solutions include, for example, 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 and N-methylpyrrolidinone; nitrile solvents such as acetonitrile and 3-methoxypropionitrile; and water.
Examples of electrolytes 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 Decanedicarboxylic acids such as ,6-decanedicarboxylic acid, octanedicarboxylic acids such as 1,7-octanedicarboxylic acid, organic acids such as azelaic acid and sebacic acid; Hydric alcohol complex compound; inorganic acids such as phosphoric acid, carbonic acid, silicic acid, etc. as anion components, primary amines (methylamine, ethylamine, propylamine, butylamine, ethylenediamine, etc.), secondary amines (dimethylamine, diethylamine, di propylamine, methylethylamine, diphenylamine, etc.), tertiary amines (trimethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo(5,4,0)-undecene-7, etc.), tetraalkylammonium (tetra electrolytes containing cationic components such as methylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium and dimethyldiethylammonium;

<Effect>
By including the compound represented by formula (1) in the solid electrolyte layer of the capacitor of the present invention, it is possible to obtain a capacitor having a lower equivalent series resistance and superior heat resistance than conventional capacitors. Although the mechanism is not clear, it is presumed that the compound improves the electrical conductivity of the solid electrolyte layer, thereby reducing its equivalent series resistance.
Further, by including the compound represented by the formula (1) in the solid electrolyte layer of the capacitor of the present invention, the heat resistance of the capacitor can be improved. Although the mechanism for this is unknown, it is presumed that the compound improves the stability of the conductive composite contained in the solid electrolyte layer, thereby improving its heat resistance.

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

The conductive polymer dispersion contains at least one compound represented by the formula (1), and is a dispersion in which a conductive composite containing a π-conjugated conductive polymer and a polyanion is dispersed. be.
The conductive polymer dispersion may contain the nitrogen-containing compound, the polyol compound, additives 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 material of valve metal.
As a method of forming the dielectric layer 12, for example, a method of anodizing the surface of the anode 11 in an electrolytic solution for chemical conversion treatment such as an ammonium adipate aqueous solution, an ammonium borate aqueous solution, or an ammonium phosphate aqueous solution can be mentioned. .

The cathode forming step is a step of arranging 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 so as to face the dielectric layer 12. be done.

The solid electrolyte layer forming step is a step of applying the conductive polymer dispersion to at least 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 composite, and examples thereof include water, organic solvents, and mixtures of water and organic solvents. be done.
Examples of organic solvents 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 alcohol solvents include methanol, ethanol, isopropanol, n-butanol, t-butanol, allyl alcohol and the like.
Examples of ether-based solvents include diethyl ether, dimethyl ether, ethylene glycol, propylene glycol, propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, and propylene glycol dialkyl ethers.
Ketone solvents include, for example, 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 ester-based solvents include ethyl acetate, propyl acetate, and butyl acetate.
Examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, ethylbenzene, propylbenzene, isopropylbenzene and the like.

Examples of additives include surfactants, inorganic conductive agents, antifoaming agents, coupling agents, antioxidants, and ultraviolet absorbers. However, the additive is a compound other than the compound represented by formula (1), the conductive composite, the nitrogen-containing compound, the polyol compound, and the solvent (dispersion medium).
Examples of surfactants include nonionic, anionic, and cationic surfactants, with nonionic surfactants being preferred from the standpoint of storage stability. Polymer surfactants such as polyvinyl alcohol and polyvinylpyrrolidone may also be added.
Examples of inorganic conductive agents include metal ions and conductive carbon. Metal ions can be generated by dissolving metal salts in water.
Antifoaming agents include silicone resins, polydimethylsiloxane, silicone oils and the like.
Examples of coupling agents include silane coupling agents having a vinyl group, an amino group, an epoxy group, or the like.
Antioxidants include phenol antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, sugars and the like.
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 relative to the total mass of the conductive polymer dispersion is not particularly limited, and the content is preferably a content that provides a viscosity that facilitates coating. 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 even more preferable.

The total content of the compound represented by the formula (1) (compound 1) 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 facilitates application. Specifically, for example, it can be 0.001% by mass or more and 10% by mass or less.

The total content of Compound 1 contained in the conductive polymer dispersion is preferably 10 parts by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the conductive composite contained in the conductive polymer dispersion. It is more preferably from 30 to 500 parts by mass, particularly preferably from 40 to 400 parts by mass, and most preferably from 50 to 200 parts by mass.
Within the above range, when a capacitor is produced using the conductive polymer dispersion according to the present invention, the equivalent series resistance of the capacitor is more likely to be lowered and the heat resistance is more likely to be improved, which is 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. 1 to 100 parts by mass is preferable, 1 to 100 parts by mass is more preferable, 5 to 50 parts by mass is even more preferable, and 10 to 30 parts by mass is particularly preferable.
Within the above range, when a capacitor is produced using the conductive polymer dispersion according to the present invention, the equivalent series resistance of the capacitor is more likely to be lowered and the heat resistance is more likely to be improved, which is preferable.

When the conductive polymer dispersion contains the polyol compound, the content ratio is appropriately determined according to the type of the polyol compound. It is preferably 100 parts by mass or more and 10000 parts by mass or less, more preferably 200 parts by mass or more and 2000 parts by mass or less, and even more preferably 300 parts by mass or more and 1000 parts by mass or less.

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

Examples of the method for preparing the conductive polymer dispersion include a method of oxidative polymerization of a precursor monomer forming a π-conjugated conductive polymer in the presence of a polyanion and a dispersion medium.
The compound represented by the formula (1) is added to the obtained conductive polymer dispersion, and if necessary, the nitrogen-containing compound, the compound having two or more hydroxy groups, additives, etc. can be added.
For the purpose of improving the dispersibility of each material contained in the conductive polymer dispersion, it is preferable to subject the conductive polymer dispersion to a known high-dispersion treatment prior to application, in which the conductive polymer dispersion is dispersed while applying a shearing force.

As a method for applying the conductive polymer dispersion, for example, immersion (dip coating), comma coating, reverse coating, lip coating, microgravure coating, etc. 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 its manufacturing method of the present invention are not limited to the above-described embodiments.
A separator may be provided between the dielectric layer and the cathode in the capacitor of the present invention.
A wound type capacitor is an example of a capacitor provided with a separator between a dielectric layer and a cathode.
Examples of separators include sheets (including nonwoven fabrics) made of cellulose, polyvinyl alcohol, polyester, polyethylene, polystyrene, polypropylene, polyimide, polyamide, polyvinylidene fluoride, etc., and nonwoven fabrics of glass fibers.
The density of the separator is preferably in the range of 0.1 g/cm ³ or more and 1.0 g/cm ³ or less, more preferably in the range of 0.2 g/cm ³ or more and 0.8 g/cm ³ or less.
When a separator is provided, a method of forming a cathode by impregnating the separator with carbon paste or silver paste can also be applied.

(Production example 1)
Dissolve 206 g of sodium styrenesulfonate in 1000 ml of ion-exchanged water, add 1.14 g of ammonium persulfate oxidizing agent solution previously dissolved in 10 ml of water dropwise for 20 minutes while stirring at 80° C., and keep this solution for 12 hours. Stirred.
1000 ml of sulfuric acid diluted to 10% by mass was added to the resulting sodium styrenesulfonate-containing solution, and about 1000 ml of the solvent in the polystyrenesulfonic acid-containing solution was removed by ultrafiltration. 2000 ml of ion-exchanged water was added to the residual liquid, about 2000 ml of the solvent was removed by ultrafiltration, and the polystyrene sulfonic acid was washed with water. This ultrafiltration operation was repeated three times.
Water in the obtained solution was removed under reduced pressure to obtain a 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 polystyrenesulfonic acid obtained in Production Example 1 in 2000 ml of deionized water was mixed at 20°C.
The resulting mixed solution was kept at 20° C., and while stirring, 29.64 g of ammonium persulfate and 8.0 g of ferric sulfate oxidation catalyst solution dissolved in 200 ml of ion-exchanged water were slowly added, and the mixture was stirred for 3 hours. The mixture was stirred and reacted.
2000 ml of ion-exchanged water was added to the resulting reaction solution, and about 2000 ml of the solution was removed by ultrafiltration. This operation was repeated three times.
200 ml of 10 mass % diluted sulfuric acid and 2000 ml of ion-exchanged water were added to the obtained solution, and about 2000 ml of the solvent was removed by ultrafiltration. 2000 ml of ion-exchanged water was added to the residual liquid, about 2000 ml of the solvent was removed by ultrafiltration, and the polystyrenesulfonic acid-doped poly(3,4-ethylenedioxythiophene) (PEDOT-PSS) was washed with water. This operation was repeated eight times to obtain a 1.60% by mass 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 a 10% by mass ammonium adipate aqueous solution to chemically convert (oxidize) to form a dielectric layer on both sides of the aluminum foil. formed to obtain an anode foil.
Next, opposing aluminum cathode foils to which cathode lead terminals were welded were laminated on both sides of the anode foil with a separator made of cellulose interposed therebetween.

(Formulation example)
A nitrogen-containing compound and a After adding an additive compound and stirring at room temperature, dispersion treatment was performed at a pressure of 100 MPa using a high-pressure disperser to obtain a conductive polymer dispersion.

<Test 1> Evaluation of Solid Electrolytic Capacitor The capacitor element obtained in Production Example 3 was immersed in the conductive polymer dispersion obtained in the above formulation example under reduced pressure, and then dried in a hot air dryer at 125°C for 30 minutes. This step was performed once to form a solid electrolyte layer containing the conductive composite on the surface of the dielectric layer.
Then, the capacitor element having the solid electrolyte layer formed thereon was placed in an aluminum case and sealed with a sealing rubber to obtain a capacitor.
[Capacitance/Equivalent series resistance]
For each capacitor, an LCR meter ZM2376 (manufactured by NF Circuit Design Block Co., Ltd.) was used to measure the capacitance (Cap.) at 120 Hz and the equivalent series resistance (ESR) at 100 kHz. Table 2 shows the measurement results.

From the results in Table 2, it is clear that the ESR of the examples according to the invention is lower than the ESR of the comparative examples. Also, the capacitances of the examples are generally larger than the capacitances of the comparative examples, and it can be seen that they are suitable for applications requiring large capacities.
The ESR of Comparative Example 4 is relatively low, but this is largely due to the combined use of imidazole and glycerol. Example 8, which contains the same amount of imidazole as Comparative Example 4 and contains the same amount of guaiacol glycerol ether instead of glycerol, has a lower ESR than that of Comparative Example 4.

<Test 2> Evaluation of Heat Resistance of Solid Electrolytic Capacitor The capacitor element obtained in Production Example 3 was immersed in the conductive polymer dispersion obtained in the above formulation example under reduced pressure. The step of drying for 2 minutes was repeated twice to form a solid electrolyte layer containing the conductive composite on the surface of the dielectric layer.
Then, the capacitor element having the solid electrolyte layer formed thereon was placed in an aluminum case and sealed with a sealing rubber to obtain a capacitor.
[Capacitance/Equivalent series resistance]
For each capacitor, an LCR meter ZM2376 (manufactured by NF Circuit Design Block Co., Ltd.) was used to measure the capacitance (Cap.) at 120 Hz and the equivalent series resistance (ESR) at 100 kHz. Table 3 shows the measurement results.
[Heat resistance test]
The capacitor obtained above was placed in a hot air dryer at 145° C., taken out after 500 hours, and cooled at room temperature for 30 minutes. After cooling, the capacitance (Cap.) at 120 Hz and the equivalent series resistance (ESR) at 100 kHz were measured using an LCR meter ZM2376 (manufactured by NF Circuit Design Block Co., Ltd.). Table 3 shows the measurement results.

From the results in Table 3, it is clear that the ESR of the examples according to the present invention remains low even after the heat resistance test, and is superior in heat resistance to the ESR of the comparative examples.
The ESR of Comparative Example 9 is relatively low even after the heat resistance test, but this is largely due to the combined use of imidazole and glycerol. The ESR of Example 9, which contains the same amount of imidazole as Comparative Example 9 and contains the same amount of guaiacol glycerol ether instead of glycerol, is lower than that of Comparative Example 9 even after the heat resistance test.

<Test 3> Evaluation of heat resistance of electrolytic capacitor The capacitor element obtained in Production Example 3 was immersed in the conductive polymer dispersion obtained in the above formulation example under reduced pressure, and then dried in a hot air dryer at 125°C for 30 minutes. A drying step was performed once to form a solid electrolyte layer containing the conductive composite on the surface of the dielectric layer.
Next, the capacitor element having the solid electrolyte layer formed thereon and the electrolytic solution were placed in an aluminum case and sealed with a sealing rubber to obtain a capacitor.
[Capacitance/Equivalent series resistance]
For each capacitor, an LCR meter ZM2376 (manufactured by NF Circuit Design Block Co., Ltd.) was used to measure the capacitance (Cap.) at 120 Hz and the equivalent series resistance (ESR) at 100 kHz. Table 4 shows the measurement results.
[Heat resistance test]
The capacitor obtained above was placed in a hot air dryer at 145° C., taken out after 500 hours, and cooled at room temperature for 30 minutes. After cooling, the capacitance (Cap.) at 120 Hz and the equivalent series resistance (ESR) at 100 kHz were measured using an LCR meter ZM2376 (manufactured by NF Circuit Design Block Co., Ltd.). Table 4 shows the measurement results.

From the results in Table 4, it is clear that the ESR of the examples according to the present invention remains low even after the heat resistance test, and is superior in heat resistance to the ESR of the comparative examples.

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

Claims (17)

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

[In formula (1), R represents a hydrogen atom or an arbitrary substituent, and m represents an integer of 1 to 5. ] 2. The conductive polymer dispersion according to claim 1, containing a compound represented by the following formula (1), wherein at least one R is a methoxy group. 2. The conductive polymer dispersion according to claim 1, containing guaiacol glycerol ether, which is the compound represented by formula (1). 4. The conductive polymer dispersion according to any one of claims 1 to 3, further comprising at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine. 5. The conductive polymer dispersion according to claim 4, containing imidazole as said nitrogen-containing aromatic cyclic compound. 5. The conductive polymer dispersion according to claim 4, containing triethylamine as the tertiary amine. The conductive polymer dispersion according to any one of claims 1 to 6, wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene). The conductive polymer dispersion according to any one of claims 1 to 7, wherein the polyanion is polystyrenesulfonic acid. an anode made of a porous material of a valve metal; a dielectric layer made of an oxide of the valve metal; a cathode made of a conductive material provided on a side of the dielectric layer opposite to the anode; and the dielectric layer. and a solid electrolyte layer formed between the cathodes,
A capacitor, wherein the solid electrolyte layer comprises a conductive composite containing a π-conjugated conductive polymer and a polyanion, and at least one compound represented by the following formula (1).

[In formula (1), R represents a hydrogen atom or an arbitrary substituent, and m represents an integer of 1 to 5. ] 10. The capacitor according to claim 9, wherein said solid electrolyte layer contains the compound represented by said formula (1), wherein at least one R is a methoxy group. 11. The capacitor according to claim 10, wherein said solid electrolyte layer contains guaiacol glycerol ether, which is the compound represented by formula (1). The capacitor according to any one of claims 9 to 11, wherein said solid electrolyte layer further contains at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine. 13. The capacitor according to claim 12, wherein said solid electrolyte layer contains imidazole as said nitrogen-containing aromatic cyclic compound. 13. The capacitor according to claim 12, wherein said solid electrolyte layer contains triethylamine which is said tertiary amine. The capacitor according to any one of claims 9 to 14, wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene). A capacitor according to any one of claims 9 to 15, wherein said polyanion is polystyrene sulfonic acid. a step of forming a dielectric layer by oxidizing the surface of an anode made of a porous material of valve metal;
a step of arranging a cathode at a position facing the dielectric layer; applying the conductive polymer dispersion according to any one of claims 1 to 8 to the surface of the dielectric layer; and forming an electrolyte layer.

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