JP2023069382A - Conductive polymer dispersion liquid, capacitor, and manufacturing method thereof - Google Patents

Abstract

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

Description

TECHNICAL FIELD The present invention relates to a capacitor having a solid electrolyte layer containing a π-conjugated conductive polymer and a manufacturing method thereof.

Capacitors are known in which a solid electrolyte layer formed from a conductive polymer dispersion containing poly(3,4-ethylenedioxythiophene) and polystyrenesulfonic acid is disposed between a dielectric layer and a cathode (for example, Patent document 1).

JP 2019-87615 A

Conventional capacitors manufactured using conductive polymer dispersions are required to have increased capacitance and reduced equivalent series resistance.
INDUSTRIAL APPLICABILITY The present invention provides a capacitor having a capacitance equivalent to that of conventional capacitors and a reduced equivalent series resistance, a method for producing the same, and a conductive polymer dispersion suitable for the method for producing the same.

[1] A conductive composite containing a π-conjugated conductive polymer and a polyanion, at least one compound represented by the following formula (1) or (2), a nitrogen-containing aromatic cyclic compound, and A conductive polymer dispersion containing at least one of tertiary amines and a dispersion medium.
[2] The conductive polymer dispersion according to [1], which contains the nitrogen-containing aromatic cyclic compound, and the nitrogen-containing aromatic cyclic compound has a vinyl group, an allyl group, an acrylic group, or a methacrylic group. liquid.
[3] The conductive polymer dispersion according to [1] or [2], which contains the tertiary amine, and the tertiary amine has a vinyl group, an allyl group, an acrylic group, or a methacrylic group.
[4] Any one of [1] to [3], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene), or the polyanion is polystyrenesulfonic acid. Conductive polymer dispersion according to.
[5] 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 opposite side of the dielectric layer 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; At least one of the compounds represented by the formula (2), or a reaction product in which the terminal functional groups of one or more compounds represented by the following formula (1) are polymerized with each other, or by the following formula (2) A capacitor containing a reaction product in which terminal functional groups of one or more compounds represented are polymerized with each other, and at least one of a nitrogen-containing aromatic cyclic compound and a tertiary amine.
[6] The solid electrolyte layer is a reaction product in which terminal functional groups of one or more compounds represented by the formula (1) are polymerized with each other, or one or more compounds represented by the formula (2) The capacitor according to [5], which contains a reaction product in which terminal functional groups of the compound are polymerized with each other.
[7] The solid electrolyte layer contains the nitrogen-containing aromatic cyclic compound, and the nitrogen-containing aromatic cyclic compound has a vinyl group, an allyl group, an acrylic group, or a methacrylic group, and through the functional group, and at least part of the nitrogen-containing aromatic cyclic compound is bonded to at least part of the compound represented by formula (1) or (2), according to [5] or [6] capacitor.
[8] The solid electrolyte layer contains the tertiary amine, and the tertiary amine has a vinyl group, an allyl group, an acrylic group, or a methacrylic group. The capacitor according to any one of [5] to [7], at least a portion of which is bonded to at least a portion of the compound represented by formula (1) or (2).
[9] Any one of [5] to [8], wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene), or the polyanion is polystyrenesulfonic acid. The capacitor described in .
[10] applying the conductive polymer dispersion according to any one of [1] to [4] to the surface of a dielectric layer formed on the surface of an anode made of a porous material of a valve metal; A method for manufacturing a capacitor, comprising a step of drying to form a solid electrolyte layer.

The capacitor of the present invention contains a compound represented by a specific formula and a nitrogen-containing aromatic cyclic compound in the solid electrolyte layer, so that it has a capacitance equivalent to that of conventional capacitors and a reduced equivalent series resistance. are doing. According to the capacitor manufacturing method of the present invention, the capacitor can be easily manufactured by using the conductive polymer dispersion of the present invention.

The present invention is considered to contribute to SDGs Goal 12 “Responsible consumption and production”.

In the present specification and claims, the lower limit and upper limit of the numerical range indicated by "-" shall be included in the numerical range.

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

《Capacitor》
A first aspect of the present invention is a capacitor. An example of the embodiment will be described with reference to the drawings. A capacitor 10 shown in FIG. and a cathode 13 provided on the front 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 As with the anode 11, the dielectric layer 12 is also formed with irregularities (see FIG. 1).

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.

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

［式（１）中、Ｒ_１、Ｒ_２はそれぞれ独立に水素原子または任意の置換基を表し、ｎは整数を表す。式（２）中、Ｒ_１、Ｒ_２、Ｒ_３はそれぞれ独立に水素原子または任意の置換基を表し、ｌ、ｍ、ｎは整数を表し、ｌ＋ｍ＋ｎ＝９～２０を満たす。］

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

R ₁ and R ₂ in formula (1) are preferably a hydrogen atom or a methyl group.
n in formula (1) is preferably 0 to 100, more preferably 1 to 30, still more preferably 1 to 20, particularly preferably 2 to 10, and most preferably 3 to 7.
According to the preferred embodiment described above, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.
The compound (1) contained in the solid electrolyte layer may be one kind, or two or more kinds.

R ₁ , R ₂ and R ₃ in formula (2) are preferably a hydrogen atom or a methyl group.
Each of l, m, and n in formula (2) is preferably 0 to 18, more preferably 2 to 10, and even more preferably 3 to 7, independently.
The sum of l+m+n in formula (2) is 9 to 20, preferably 9 to 18, more preferably 9 to 15, and even more preferably 9 to 12.
According to the preferred embodiment described above, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.
The compound (2) contained in the solid electrolyte layer may be one kind, or two or more kinds.

The total content of the compound (1) and the compound (2) contained in the solid electrolyte layer was 10 to 5000 parts by mass is preferable, 100 to 1000 parts by mass is more preferable, 200 to 800 parts by mass is even more preferable, and 300 to 600 parts by mass is most preferable.
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

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

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

In the present invention, nitrogen-containing aromatic cyclic compounds (aromatic compounds in which at least one nitrogen atom forms a ring structure) can be broadly classified according to the presence or absence of a vinyl polymerizable group.
Here, the vinyl-based polymerizable group means a polymerizable group having a vinyl group, and examples thereof include a vinyl group, an allyl group (aryl group), an acrylic group, and a methacrylic group.

Nitrogen-containing aromatic cyclic compounds having no vinyl polymerizable group 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.

When the solid electrolyte layer contains one or more nitrogen-containing aromatic cyclic compounds having no vinyl-based polymerizable group, the total content thereof is 100 parts by mass in total of the π-conjugated conductive polymer and the polyanion. (That is, 100 parts by mass of the conductive composite) is preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 50 parts by mass or less, and even more preferably 15 parts by mass or more and 30 parts by mass or less.
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

Nitrogen-containing aromatic cyclic compounds having a vinyl polymerizable group include, for example, 1-vinylimidazole, 2-methyl-1-vinylimidazole, 1-methyl-3-[3-(acryloyloxy)propyl]- 1H-imidazol-3-ium, 1-allylimidazole, 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine and the like.

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

In the present invention, tertiary amines can be roughly classified according to the presence or absence of a vinyl polymerizable group.
Here, the vinyl-based polymerizable group means a polymerizable group having a vinyl group, and examples thereof include a vinyl group, an allyl group (aryl group), an acrylic group, and a methacrylic group.

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

When the solid electrolyte layer contains one or more tertiary amines having no vinyl-based polymerizable group, the total content thereof is 100 parts by mass in total of the π-conjugated conductive polymer and the polyanion (that is, the conductive 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 70 parts by mass or less, and even more preferably 25 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the composite).
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

Tertiary amines having a vinyl polymerizable group include, for example, dimethylaminopropylacrylamide (abbreviation: DMAPAA), 2-(dimethylamino)ethyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)methacrylate, dimethylamino)ethyl, 2-(diethylamino)ethyl methacrylate, triallylamine, N-allyldimethylamine, N-allyldiethylamine and the like.

When the solid electrolyte layer contains one or more tertiary amines having a vinyl-based polymerizable group, the total content thereof is 100 parts by mass in total of the π-conjugated conductive polymer and polyanion (that is, the conductive composite 10 parts by mass or more and 200 parts by mass or less, more preferably 20 parts by mass or more and 100 parts by mass or less, and even more preferably 30 parts by mass or more and 70 parts by mass or less.
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

The nitrogen-containing compound contained in the solid electrolyte layer preferably has the vinyl polymerizable group. In this case, at least part of the nitrogen-containing compound contained in the solid electrolyte layer is preferably bonded to each other by a polymerization reaction via the vinyl-based polymerizable group. At least a portion of the nitrogen-containing compound may be bonded to at least a portion of the compound (1) through a polymerization reaction via the vinyl polymerizable group, or may be bonded to at least a portion of the compound (2). You may couple|bond with respect to one part.
These bonds improve the adhesion of the solid electrolyte layer to the dielectric layer, improve the physical strength of the solid electrolyte layer, and improve the durability of the solid electrolyte layer against external stress.

<Conductive composite>
Next, the conductive composite contained in the solid electrolyte layer will be described. The conductive composite of this embodiment contains a π-conjugated conductive polymer and a polyanion. The polyanion in the conductive composite forms a conductive composite having conductivity by doping the π-conjugated conductive polymer.
In the polyanion, only some of the anionic groups are doped into the π-conjugated conductive polymer, and there are surplus anionic groups that do not participate in the doping. Since the surplus anionic groups are hydrophilic groups, the conductive composite has water dispersibility.

(π-conjugated conductive polymer)
The π-conjugated conductive polymer may be any organic polymer having a π-conjugated main chain. molecules, polyphenylene-based conductive polymers, polyphenylene-vinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophene-vinylene-based conductive polymers, copolymers thereof, and the like. Polypyrrole-based conductive polymers, polythiophenes and polyaniline-based conductive polymers are preferable from the viewpoint of stability in air, and polythiophene-based conductive polymers are more preferable from the viewpoint of transparency.

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

(polyanion)
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 improves 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 such polyanions include polystyrenesulfonic acid, polyvinylsulfonic acid, polyallylsulfonic acid, polyacrylic acid esters having a sulfo group, polymethacrylic acid esters having a sulfo group (e.g., poly(4-sulfobutyl methacrylate) , polysulfoethyl 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, Polymers having carboxy groups such as polyallylcarboxylic acid, polyacrylic acid, polymethacrylic acid, poly(2-acrylamido-2-methylpropanecarboxylic acid), polyisoprenecarboxylic acid, etc. A polyanion is a single monomer. may be a homopolymer obtained by polymerizing or a copolymer obtained by polymerizing two or more monomers.
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 is a mass-based average molecular weight determined by pullulan conversion using gel filtration chromatography.

The content of the polyanion in the conductive composite is preferably in the range of, for example, 1 part by mass or more and 1000 parts by mass or less with respect to 100 parts by mass of the π-conjugated conductive polymer, and 10 parts by mass or more and 700 parts by mass. It is more preferably not more than 100 parts by mass, and more preferably 100 parts by mass or more and 500 parts by mass or less. If the polyanion content is at least the above lower limit, the doping effect on the π-conjugated conductive polymer tends to be stronger, resulting in higher conductivity. On the other hand, if the polyanion content is equal to or less than the above upper limit, the π-conjugated conductive polymer can be sufficiently contained, and sufficient conductivity can be ensured.

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

<Polyol compound>
In the solid electrolyte layer, a compound having two or more hydroxy groups (hereinafter referred to as polyol may be referred to as a compound.) may be further included. By containing the polyol compound, the equivalent series resistance 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 the electrolyte described below.

When one or more of the polyol compounds are contained in the solid electrolyte layer, the total content thereof is, for example, 50 parts by mass or more and 2000 parts by mass with respect to 100 parts by mass of the conductive composite contained in the solid electrolyte layer. The following is preferable, 100 to 1000 parts by mass is more preferable, and 300 to 600 parts by mass is even more preferable.
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

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

[Electrolyte]
The solid electrolyte layer 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; sulfur solvents such as sulfolane, dimethylsulfoxide and dimethylsulfone; amide solvents such as N-methylformamide, N,N-dimethylformamide, N-methylacetamide and N-methylpyrrolidinone; acetonitrile and 3-methoxypropionitrile; Nitrile-based solvents, water, and the like can be mentioned.
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;

<<Manufacturing Method of Capacitor>>
In the second aspect of the present invention, a conductive polymer dispersion, which will be described later, is applied to the surface of a dielectric layer formed on the surface of an anode made of a porous material of a valve metal, and dried to form a solid electrolyte layer. A method for manufacturing a capacitor, comprising steps. By the production method of this aspect, the capacitor of the first aspect can be easily produced.

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

[Dielectric forming step]
In this step, the dielectric layer 12 is formed by oxidizing the surface of the anode 11 made of a porous material of valve metal. The method of forming the dielectric layer 12 is not particularly limited. For example, the surface of the anode 11 is anodized in an electrolytic solution for chemical conversion such as an ammonium adipate aqueous solution, an ammonium borate aqueous solution, or an ammonium phosphate aqueous solution. method.

[Cathode forming step]
In this step, the cathode 13 is arranged at a position facing the dielectric layer 12 . The method of arranging the cathode 13 is not particularly limited. For example, a method of forming the cathode 13 using a conductive paste such as carbon paste or silver paste, or a method of arranging a metal foil such as an aluminum foil so as to face the dielectric layer 12. etc.

[Film formation process]
In this step, the solid electrolyte layer 14 is formed by applying a conductive polymer dispersion described later on at least part of the surface of the dielectric layer 12 and drying it.
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 methods, the method of immersing the anode 11 in the conductive polymer dispersion under reduced pressure is preferable. With the immersion method, the conductive polymer dispersion can be sufficiently applied to the inside of the porous structure on the surface of the dielectric layer 12 . After immersion, it is taken out and proceeded to the next drying treatment.

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

Within the above temperature range and drying time, a polymerization reaction occurs through the terminal polymerizable groups of the compound (1) and the compound (2), and the adhesion of the formed solid electrolyte layer 14 to the dielectric layer 12 is improved. As a result, the physical strength of the solid electrolyte layer 14 is improved, and the durability of the solid electrolyte layer 14 against external stress is improved.
Further, when the nitrogen-containing compound contained in the solid electrolyte layer 14 is a compound having a vinyl-based polymerizable group, the nitrogen-containing compounds undergo a polymerization reaction with each other in the drying treatment, or the compound (1) or the compound ( 2) and the nitrogen-containing compound undergo a polymerization reaction to improve the adhesion of the formed solid electrolyte layer 14 to the dielectric layer 12, improve the physical strength of the solid electrolyte layer 14, and improve the solid electrolyte layer against external stress. 14 durability is improved.

After drying, the capacitor may be assembled by a conventional method.

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

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

<Dispersion medium>
The dispersion medium that constitutes the conductive polymer dispersion of this embodiment is not particularly limited as long as it is a liquid that can disperse the conductive composite. For example, water, an organic solvent, or a mixture of water and an organic solvent. liquid.
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.

The content of the π-conjugated conductive polymer and the polyanion (that is, the content of the conductive composite) with respect to the total mass of the conductive polymer dispersion is, for example, preferably 0.1% by mass or more and 10% by mass or less, 0.2% by mass or more and 5% by mass or less is more preferable, and 0.3% by mass or more and 2% by mass or less is even more preferable.
Within the above preferred range, the dispersibility of the conductive composite in the conductive polymer dispersion can be further enhanced.

The total content of compound (1) and compound (2) contained in the conductive polymer dispersion is 100 parts by mass of the π-conjugated conductive polymer and polyanion (that is, 100 parts by mass of the conductive composite). On the other hand, it is preferably 10 to 5000 parts by mass, more preferably 100 to 1000 parts by mass, even more preferably 200 to 800 parts by mass, and most preferably 300 to 600 parts by mass.
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

The total content of the nitrogen-containing compounds contained in the conductive polymer dispersion is preferably such that the pH of the conductive polymer dispersion (25° C.) is 2.0 to 8.0. A content of 0 to 5.0 is more preferable, and a content of 2.0 to 3.0 is even more preferable.
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the manufactured capacitor.

When the conductive polymer dispersion contains one or more nitrogen-containing aromatic cyclic compounds that do not have a vinyl polymerizable group, the total content thereof is the sum of the π-conjugated conductive polymer and the polyanion. With respect to 100 parts by mass (that is, 100 parts by mass of the conductive composite), it is preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 50 parts by mass or less, and 15 parts by mass or more and 30 parts by mass or less. preferable.
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

When the conductive polymer dispersion contains one or more nitrogen-containing aromatic cyclic compounds having a vinyl polymerizable group, the total content of the π-conjugated conductive polymer and polyanion is 100. It is preferably 8 parts by mass or more and 100 parts by mass or less, more preferably 14 parts by mass or more and 70 parts by mass or less, and even more preferably 20 parts by mass or more and 40 parts by mass or less, relative to parts by mass (that is, 100 parts by mass of the conductive composite). .
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

When the conductive polymer dispersion contains one or more tertiary amines having no vinyl polymerizable group, the total content thereof is 100 parts by mass in total of the π-conjugated conductive polymer and the polyanion ( That is, it is preferably 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 70 parts by mass or less, and even more preferably 25 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the conductive composite.
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

When the conductive polymer dispersion contains one or more tertiary amines having a vinyl polymerizable group, the total content thereof is 100 parts by mass in total of the π-conjugated conductive polymer and the polyanion (that is, 10 parts by mass or more and 200 parts by mass or less, more preferably 20 parts by mass or more and 100 parts by mass or less, and even more preferably 30 parts by mass or more and 70 parts by mass or less, relative to 100 parts by mass of the conductive composite).
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

The conductive polymer dispersion of this aspect may contain one or more of the polyols described in the first aspect. When one or more of the polyol compounds are contained, the total content thereof is, for example, a total of 100 parts by mass of the π-conjugated conductive polymer and polyanion (that is, 100 parts by mass of the conductive composite), 50 to 2000 parts by mass is preferable, 100 to 1000 parts by mass is more preferable, and 300 to 600 parts by mass is even more preferable.
Within the above range, it is possible to further reduce the ESR while suppressing a decrease in the capacitance of the capacitor.

The conductive polymer dispersion may contain any additive, and the content ratio thereof is appropriately determined according to the type of additive. It can be up to 1000 parts by mass.
Here, the optional additive is a compound other than the conductive composite, the nitrogen-containing compound, the compound (1) and the compound (2), the polyol compound and the dispersion medium (solvent).

Optional additives include, for example, surfactants, inorganic conductive agents, antifoaming agents, coupling agents, antioxidants, ultraviolet absorbers, and the like.
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 conductive polymer dispersion of this embodiment can be produced by mixing each component and dispersing the conductive composite by a conventional method.

(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 to obtain a polystyrenesulfonic acid-containing solution, and about 1000 ml of the solvent was removed from the polystyrenesulfonic acid-containing solution 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 polystyrenesulfonic acid-doped poly(3,4-ethylenedioxythiophene) (PEDOT-PSS) contained in the solution was washed with water. . This operation was repeated 8 times to obtain a PEDOT-PSS aqueous dispersion of 1.60% by mass.

(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, and wound into a cylindrical shape to obtain a capacitor element.

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

(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.
The amount of the nitrogen-containing compound added in each formulation example was adjusted so that the number of moles of each was approximately equal, and the pH of each conductive polymer dispersion (25° C.) was within the range of 2.0 to 3.0. .

Abbreviations in Table 1 represent the following.
"DMAPAA": dimethylaminopropyl acrylamide "A-200": polyethylene glycol #200 di(meth)acrylate: compound represented by R ₁ , R ₂ =H, n = 4 in formula (1) "A-400" : Polyethylene glycol #400 di(meth)acrylate: Compound represented by R ₁ , R ₂ =H, n = 9 in formula (1) "A-600": Polyethylene glycol #600 di(meth)acrylate: Formula ( 1) Compound represented by R ₁ , R ₂ = H, n = 14 “A-1000”: polyethylene glycol #1000 di(meth)acrylate: R ₁ , R ₂ = H, n = in formula (1) Compound represented by 23 "GLY-9E": ethoxylated glycerol triacrylate: compound represented by R ₁ , R ₂ , R ₃ =H, n + m + l = 9 in formula (2)

<Capacitor manufacturing>
After 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 30 minutes with a hot air dryer at 125°C was repeated once to obtain a dielectric. A solid electrolyte layer containing the conductive composite was formed on the surface of the body layer.
Next, the capacitor element having the solid electrolyte layer formed thereon and the driving electrolytic solution obtained in Production Example 4 were placed in an aluminum case, and sealed with sealing rubber to obtain a capacitor.

<Measurement of capacitance and 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.

The capacitors of each example containing the specific nitrogen-containing compound and the additive compound exhibited equivalent capacitances and equivalent series resistances superior to those of the comparative examples.

When the conductive layer formed on the dielectric layer of the anode foil was carefully observed and rubbed against the conductive layer with a needle when the capacitors of each test example were manufactured, it was found that Examples 1 to 18 were stronger than Comparative Examples 1 to 4. , high adhesion of the conductive layer to the dielectric layer, and high physical strength of the conductive layer.
This result is believed to be due to the fact that the compound (1) or compound (2) having acrylic groups at both ends of the molecule was used in Examples 1 to 18, and these were polymerized by heating during the drying process. be done. That is, in Examples 1 to 18, since the compound (1) or compound (2) having a polymerizable group at both ends of the molecule is used, the adhesion of the conductive layer to the substrate is excellent, and resistance to physical stress It was confirmed that the durability was improved.

Further, when the conductive layer formed on the dielectric layer of the anode foil was carefully observed at the time of manufacturing the capacitors of each test example, and the conductive layer was rubbed with a needle, Examples 4 to 18 were found to be better than Examples 1 to 3. It was found that the adhesion of the conductive layer to the dielectric layer was higher and the physical strength of the conductive layer was higher.
This result is considered to be due to the fact that the nitrogen-containing compounds having a polymerizable vinyl group or acryl group were used in Examples 4 to 18 and were polymerized by heating during the drying process. In other words, since Examples 4 to 18 use a nitrogen-containing compound having a vinyl group or an acrylic group, the adhesion of the conductive layer to the base material is even more excellent, and the durability against physical stress is further improved. could be confirmed.

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

Claims (10)

A conductive composite containing a π-conjugated conductive polymer and a polyanion, at least one compound represented by the following formula (1) or (2), a nitrogen-containing aromatic cyclic compound, and a tertiary A conductive polymer dispersion containing at least one of amines and a dispersion medium.

[In Formula (1), R ₁ and R ₂ each independently represent a hydrogen atom or an arbitrary substituent, and n represents an integer. In formula (2), R ₁ , R ₂ and R ₃ each independently represent a hydrogen atom or an arbitrary substituent, l, m and n represent integers and satisfy l+m+n=9-20. ] 2. The conductive polymer dispersion according to claim 1, comprising said nitrogen-containing aromatic cyclic compound, said nitrogen-containing aromatic cyclic compound having a vinyl group, an allyl group, an acrylic group or a methacrylic group. 3. The conductive polymer dispersion according to claim 1, which contains the tertiary amine, and the tertiary amine has a vinyl group, an allyl group, an acrylic group, or a methacrylic group. The conductivity according to any one of claims 1 to 3, wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene), or the polyanion is polystyrenesulfonic acid. Polymer dispersion. 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 conductive composite in which the solid electrolyte layer contains a π-conjugated conductive polymer and a polyanion;
At least one of the compounds represented by the following formula (1) or the following formula (2), or a reaction product in which terminal functional groups of one or more compounds represented by the following formula (1) are polymerized with each other or a reaction product in which terminal functional groups of one or more compounds represented by the following formula (2) are polymerized with each other;
at least one of a nitrogen-containing aromatic cyclic compound or a tertiary amine;
A capacitor containing

[In Formula (1), R ₁ and R ₂ represent a hydrogen atom or any substituent, and n represents an integer. In formula (2), R ₁ , R ₂ and R ₃ represent hydrogen atoms or optional substituents, l, m and n represent integers and satisfy l+m+n=9-20. ] The solid electrolyte layer is a reaction product in which terminal functional groups of one or more compounds represented by the formula (1) are polymerized with each other, or terminals of one or more compounds represented by the formula (2). 6. The capacitor of claim 5, wherein the functional groups of contain polymerized reaction products with each other. The solid electrolyte layer contains the nitrogen-containing aromatic cyclic compound, and the nitrogen-containing aromatic cyclic compound has a vinyl group, an allyl group, an acrylic group, or a methacrylic group. 7. The capacitor according to claim 5, wherein at least part of the nitrogen-containing aromatic cyclic compound is bonded to at least part of the compound represented by formula (1) or (2). The solid electrolyte layer contains the tertiary amine, the tertiary amine has a vinyl group, an allyl group, an acrylic group, or a methacrylic group, and through the functional group, at least a portion of the tertiary amine is bound to at least part of the compound represented by formula (1) or (2). The capacitor according to any one of claims 5 to 8, wherein the π-conjugated conductive polymer is poly(3,4-ethylenedioxythiophene), or the polyanion is polystyrenesulfonic acid. The conductive polymer dispersion according to any one of claims 1 to 4 is applied to the surface of a dielectric layer formed on the surface of an anode made of a porous material of a valve metal, and dried to obtain a solid electrolyte. A method of manufacturing a capacitor, comprising a step of forming layers.

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