JP2010021217A - Solid electrolytic capacitor, and method of manufacturing the same - Google Patents

Abstract

To provide a solid electrolytic capacitor exhibiting excellent impedance characteristics, capacitance, thermal durability, low leakage current, and high withstand voltage among solid electrolytic capacitors using a conductive polymer layer as a solid electrolyte layer. .
A solid electrolytic capacitor having a solid electrolyte layer on a dielectric oxide film provided on a film-forming metal surface, wherein the solid electrolyte layer is a conductive polymer layer formed by chemical oxidative polymerization. (A) and a conductive polymer layer (B) formed by electrolytic polymerization using the conductive polymer layer (A) as an anode, and further comprising the dielectric oxide film and the conductive layer. The conductive polymer layer (A) may have a conductive polymer layer (C) made of polyaniline, and the conductive polymer layer (B) is a dopant of anthraquinone-2-sulfonic acids. A solid electrolytic capacitor characterized by including as follows.
[Selection] Figure 1

Description

  The present invention relates to a solid electrolytic capacitor using a conductive polymer layer as a solid electrolyte layer.

In recent years, with the digitization of electrical equipment and the speedup of personal computers, the capacitors used for these devices are small and large in capacity, exhibit low impedance in the high frequency range, have low leakage current, and have excellent withstand voltage. Further, it is required to have excellent heat durability.
In order to meet such demands, solid electrolytic capacitors using a conductive polymer layer having hole conductivity as a solid electrolyte layer have been developed, unlike an electrolytic type capacitor using a conventional electrolytic solution.
Such a solid electrolytic capacitor can cover the inner surface of the pore inside the anode body with a conductive polymer layer having a very high conductivity compared to the liquid electrolyte. In recent years, the amount of its use has greatly increased since it exhibits impedance.
In addition, since the performance of the solid electrolytic capacitor greatly depends on the conductive polymer layer, the development of the conductive polymer used for the conductive polymer layer is one of important issues.
Such a conductive polymer can be obtained by, for example, chemical oxidative polymerization or electrolytic polymerization, but there is a problem that must be solved in order to actually apply the conductive polymer to the solid electrolytic capacitor application. .
Specifically, when the conductive polymer is formed on the dielectric oxide film by chemical oxidative polymerization, a conductive polymer layer having high strength cannot be formed on the dielectric oxide film.
In addition, even if the conductive polymer is formed on the dielectric oxide film by electrolytic polymerization, current cannot flow because the dielectric oxide film is an electrical insulator in the first place. There is a problem that a conductive polymer layer cannot be formed on the dielectric oxide film.

As a means to solve this problem in an integrated manner, a conductive polymer layer is formed on the dielectric oxide film by chemical oxidative polymerization, and a conductive polymer layer is laminated on the conductive polymer layer by electrolytic polymerization. A solid electrolytic capacitor using a double conductive polymer layer as a solid electrolyte has been proposed.
According to this proposal, since the conductive polymer layer formed by chemical oxidative polymerization formed first can pass an electric current, it is possible to perform electropolymerization, and it is possible to form a conductive polymer layer having high strength as a whole. it can.
As a result, a solid electrolytic capacitor having a large electrostatic capacity and excellent electrical characteristics and temperature characteristics can be provided (Patent Document 1).
On the other hand, an aqueous solution of manganese nitrate is brought into contact with the dielectric oxide film, and pyrolytic manganese dioxide is deposited on the dielectric oxide film by thermal decomposition at 250 ° C., and then electropolymerization is performed, whereby anthraquinone-2-sulfonic acid is obtained. A solid electrolytic capacitor in which polypyrrole doped with sodium is formed as a conductive polymer layer has been proposed (Patent Document 2).
A solid electrolytic capacitor in which a conductive polymer layer is formed on a dielectric oxide film by chemical oxidative polymerization has also been proposed. As the conductive polymer layer, polythiophene doped with anthracene sulfonic acid is used in the solid electrolytic capacitor (Patent Document 3).

Japanese Patent Publication No. 4-74853 JP-A-3-34304 JP 2000-12394 A

However, when pyrolyzed manganese dioxide is used, the specific resistance of the pyrolyzed manganese dioxide is relatively high, and the dielectric oxide film is easily damaged when the pyrolyzed manganese dioxide is generated by pyrolysis. For this reason, there are problems such as high impedance and large leakage current.
In the case of a solid electrolytic capacitor in which a conductive polymer layer is formed by chemical oxidative polymerization on a dielectric oxide film and the conductive polymer layer includes polythiophene doped with anthracene sulfonic acid, etc. There were problems such as inferior.
Furthermore, even when a conductive polymer layer by chemical oxidative polymerization is used as an electrode and a conductive polymer layer by electrolytic polymerization is formed, due to damage to the oxide film caused by a polymerization process such as chemical oxidative polymerization or electrolytic polymerization, Leakage current may increase. Solid electrolytes made of conductive polymers, especially polypyrrole and polyaniline, have high electrical conductivity, and therefore, when applied to capacitor elements, low equivalent series resistance (ESR) can be obtained. When applied to a device, it can contribute to reducing the power consumption of the device and can be an effective energy saving means. However, in a capacitor element to which the solid electrolyte is applied as described later, the low level of the solid electrolyte is low. Heat generation during energization is reduced due to resistance, and the effect of aging treatment is weakened due to a decrease in the self-healing function of the so-called conductive polymer solid electrolyte membrane, making it difficult to reduce leakage current and increase voltage resistance.

  Normally, this increase in leakage current is caused by the generation of Joule heat due to an increase in local current flowing in the damaged part of the dielectric oxide film after energizing the element in a high-temperature and high-humidity environment after manufacturing the capacitor element. It is improved by an aging process that reduces the leakage current by carbonizing and insulating the conductive polymer film and repairing the damaged part of the dielectric oxide film. Especially when the resistance of the solid electrolyte film is low, It is difficult to obtain an aging effect and to obtain a solid electrolytic capacitor with a small leakage current and a large withstand voltage.

Accordingly, a first object of the present invention is to provide a solid electrolytic capacitor exhibiting excellent impedance characteristics, capacitance and thermal durability among solid electrolytic capacitors using a conductive polymer layer as a solid electrolyte layer. is there.
A second object of the present invention is to provide a solid electrolytic capacitor having a high withstand voltage and a reduced leakage current despite showing high capacity and low ESR.

  As a result of intensive studies to solve the above problems, the present inventor has found that a conductive polymer layer (A) formed by chemical oxidative polymerization of a conductive polymer and a conductive polymer layer formed by electrolytic polymerization. A solid electrolytic capacitor having at least (B) as a solid electrolyte layer, wherein the conductive polymer layer (B) contains anthraquinone-2-sulfonic acid as a dopant, and is suitable for the purpose of the present invention. As a result, the present invention has been completed.

  That is, the present invention is [1] a solid electrolytic capacitor having a solid electrolyte layer on a dielectric oxide film provided on a film-forming metal surface, wherein the solid electrolyte layer is formed by chemical oxidative polymerization. At least a conductive polymer layer (A) and a conductive polymer layer (B) formed by electrolytic polymerization using the conductive polymer layer (A) as an anode, and the conductive polymer layer (B) is represented by the following general formula (1)

(In the formula, X ¹ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{1 to} R ₇ are each independently a hydrogen atom or a linear or branched alkyl having 1 to 6 carbon atoms. A solid electrolytic capacitor comprising an organic sulfonate anion generated by dissociation of a compound represented by the formula:

[2] The compound represented by the general formula (1) is at least one selected from the group consisting of anthraquinone-2-sulfonic acid, anthraquinone-2-sulfonic acid organic ammonium salt, and an anthraquinone-2-sulfonic acid alkali metal salt. The solid electrolytic capacitor as described in [1] above, which is characterized by:

[3] The conductive polymer layer (A) is represented by the following general formula (2)

(In the formula, X ² represents a hydrogen atom or a halogen atom. X ³ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{8 to} R ₁₁ are each independently a hydrogen atom, a halogen atom, A linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched alkoxy group having 1 to 6 carbon atoms, a linear or branched halogenated alkyl group having 1 to 6 carbon atoms, A compound represented by an aryl group having 6 to 12 carbon atoms, a hydroxyl group, a nitro group or a cyano group), or the following general formula (3)

(In the formula, X ⁴ , X ⁵ and X ⁶ each independently represent a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R represents a hydrogen atom, a linear or branched chain having 1 to 6 carbon atoms. An organic sulfonate anion generated by dissociation of a compound represented by the formula (1) is included as a dopant, and the solid electrolytic capacitor as described in [1] or [2] above is provided. ,

[4] The solid electrolysis according to any one of [1] to [3], wherein the conductive polymer layer (A) and the conductive polymer layer (B) each contain polypyrrole. Providing a capacitor,

[5] Between the dielectric oxide film and the conductive polymer layer (A),
The solid electrolytic capacitor according to any one of claims 1 to 4, wherein a conductive polymer layer (C) made of polyaniline is provided,

[6] A step of forming a dielectric oxide film on the surface of the film-forming metal;
Forming a conductive polymer layer (A) on the dielectric oxide film by chemical oxidative polymerization;
Forming a conductive polymer layer (B) on the conductive polymer layer (A) by electrolytic polymerization, and a method for producing a solid electrolytic capacitor,
The chemical oxidative polymerization is represented by the following general formula (2)

(In the formula, X ² represents a hydrogen atom or a halogen atom. X ³ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{8 to} R ₁₁ are each independently a hydrogen atom, a halogen atom, A linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched alkoxy group having 1 to 6 carbon atoms, a linear or branched halogenated alkyl group having 1 to 6 carbon atoms, A compound having 6 to 12 carbon atoms, a hydroxyl group, a nitro group or a cyano group), or the following general formula (3),

(In the formula, X ⁴ , X ⁵ and X ⁶ each independently represent a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R represents a hydrogen atom, a linear or branched chain having 1 to 6 carbon atoms. In the presence of a compound represented by the following formula:
The electrolytic polymerization is represented by the following general formula (1)

(In the formula, X ¹ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{1 to} R ₇ are each independently a hydrogen atom or a linear or branched alkyl having 1 to 6 carbon atoms. The present invention provides a method for producing a solid electrolytic capacitor, which is carried out in the presence of a compound represented by:

[7] The compound represented by the general formula (1) is at least one selected from the group consisting of anthraquinone-2-sulfonic acid, anthraquinone-2-sulfonic acid organic ammonium salt, and an anthraquinone-2-sulfonic acid alkali metal salt. The method for producing a solid electrolytic capacitor as described in [6] above, characterized in that

[8] In the method for producing a solid electrolytic capacitor as described in [6] or [7] above,
Forming a dielectric oxide film on the film-forming metal surface;
Forming a conductive polymer layer (C) made of polyaniline on the dielectric oxide film;
Forming a conductive polymer layer (A) on the conductive polymer layer (C) by chemical polymerization;
Forming a conductive polymer layer (B) on the conductive polymer layer (A) by electrolytic polymerization;
A method for producing a solid electrolytic capacitor characterized by comprising:

[9] The method for producing a solid electrolytic capacitor as described in [8] above, wherein the conductive polymer layer (C) is formed by applying and drying an NMP solution of polyaniline. ,

[10] An electronic apparatus including the solid electrolytic capacitor according to any one of [1] to [5] is provided.

According to the present invention, among solid electrolytic capacitors using a conductive polymer layer as a solid electrolyte layer, a solid electrolytic capacitor exhibiting excellent impedance characteristics, capacitance, and thermal durability can be provided.
Furthermore, according to the present invention, a solid electrolytic capacitor having a small leakage current and a high withstand voltage can be provided.

First, the solid electrolytic capacitor of the present invention will be described.
The solid electrolytic capacitor of the present invention has a dielectric oxide film provided on the surface of a film-forming metal.
Examples of the film-forming metal used in the present invention include aluminum, tantalum, titanium, niobium, zirconium, magnesium, silicon, or one or more of these alloys.

The form of the film-forming metal is preferably a metal foil, a rod, or a sintered body mainly composed of these. More preferably, the surface of the film-forming metal is etched for the purpose of increasing the specific surface area.
The film-forming metal functions as a valve action metal, and a dielectric oxide film can be formed on the surface thereof by electrolytic oxidation, oxidizing agent oxidation, air oxidation or the like.
By performing an etching process on the film-forming metal, fine holes can be formed on the surface of the film-forming metal, and a dielectric oxide film is formed on the surface of the film-forming metal including the inside of the fine holes.

  The solid electrolytic capacitor of the present invention includes a solid electrolyte layer. The solid electrolyte layer includes a conductive polymer layer (A) formed by chemical oxidative polymerization and the conductive polymer layer (A). It has at least a conductive polymer layer (B) formed by electrolytic polymerization as an anode.

  Further, a conductive polymer layer (C) made of polyaniline by a solution coating method is formed on the surface of the dielectric oxide film, and then the conductive polymer layer (A) and then the conductive polymer layer ( B) may be formed. When the pore depth is deep, the progress of chemical polymerization in the pores may be incomplete, and the capacity expected to be obtained by increasing the pore depth may not be obtained. In such a case, the inside of the pores can be covered with the conductive polymer layer by providing the conductive polymer layer (C) formed by the solution coating method.

  As the conductive polymer layer (C), dedope polyaniline is preferably used. Although it is difficult to actually measure the conductivity of dedope polyaniline, it is presumed that the conductivity is insufficient for solid electrolyte membrane applications. However, by laminating the conductive polymer layers (A) and (B) and the conductive polymer layer (C), the conductive polymer layers (A) and (B) Regarding the conductive polymer film (C), the dopant migrated into the conductive polymer layer (C) by diffusion into the molecular layer (C) is naturally doped into the conductive polymer layer (C). It is assumed that necessary and sufficient conductivity is secured.

  Furthermore, the capacitor to which the conductive polymer layer (A) and the conductive polymer layer (B) are applied has an equivalent series resistance (ESR) higher than that of a conventional capacitor due to a decrease in resistance of the conductive polymer layer. ), But the Joule heat during energization also decreases. This makes it difficult to obtain a self-repairing action of a dielectric oxide film unique to a solid electrolytic polymer capacitor in which a so-called conductive polymer is applied to a solid electrolyte. Although details of the self-repairing mechanism of the dielectric oxide film have not been clarified, by continuing to apply a voltage to the capacitor, current concentrates on the damaged part of the dielectric oxide film, and the periphery of the damaged part. The conductive polymer layer is carbonized by Joule heat due to current concentration, and the damaged portion is filled to restore the insulating property of the dielectric oxide film.

  Therefore, a capacitor to which the conductive polymer layer (A) and the conductive polymer layer (B) are applied can obtain low ESR characteristics due to the low resistance of the conductive polymer layer. Although it is difficult to obtain a self-healing action, it can also obtain a self-healing action by inserting the conductive polymer layer (C) between the dielectric oxide film layer and the conductive polymer layer (A). Therefore, it is possible to realize a low leakage current as well as a low ESR.

  Usually, a capacitor manufacturing process includes a process for continuously applying voltage to a capacitor element under high temperature and high humidity called aging to reduce leakage current. The conductive polymer layer (C) In a device in which is applied together with the conductive polymer layers (A) and (B), such a process can be shortened, simplified, or omitted.

  In order to obtain a high capacity appearance rate, in order to increase the surface area of the dielectric oxide film, the pores due to etching tend to be deeper and the film thickness of the dielectric oxide film tends to become thinner. In the aging process, the importance of effectively utilizing such a self-repairing action is increasing.

  On the other hand, there is a field where a high withstand voltage and a low leakage current are not required in the application area of the capacitor. In the capacitor element used in such a field, the formation of the conductive polymer layer (C) is omitted, An option to reduce costs by reducing the number of steps is also possible.

Examples of the conductive polymer used in the conductive polymer layers (A) and (B) include polypyrroles such as polypyrrole, poly-3-alkylpyrrole, poly-3,4-alkylenedioxypyrrole, and polyaniline. And polyanilines such as polyalkylaniline, polyfurans such as polyfuran and polyalkylfuran, polythiophenes such as polythiophene, poly-3-alkylthiophene, and poly-3,4-alkylenedioxythiophene.
Among these, polypyrroles are preferable from the viewpoint of price and characteristics, and polypyrrole is more preferable.
The said conductive polymer can use 1 type, or 2 or more types.

The conductive polymer layer (A) used in the present invention can be formed on the dielectric oxide film by chemical oxidative polymerization.
Specifically, the conductive polymer layer (A) can be formed by bringing the monomer constituting the conductive polymer described above into contact with an oxidizing agent or the like on the dielectric oxide film. .

  Usually, a monomer solution in which the monomer is dissolved in a solvent is prepared, and the dielectric oxide film formed on the surface of the film-forming metal is impregnated with the monomer solution and then separately prepared. The conductive polymer layer (A) can be formed on the dielectric oxide film by a method such as impregnation with a liquid.

  Examples of the method of impregnating the monomer solution with respect to the dielectric oxide film formed on the surface of the film-forming metal include, for example, impregnating the monomer solution with the film-forming metal itself on which the dielectric oxide film is formed. Examples thereof include a method, a method of spraying the monomer solution onto the dielectric oxide film, and a method of applying the monomer solution onto the dielectric oxide film.

Further, as a method of impregnating an oxidant solution prepared separately after impregnating the monomer solution, for example, the film-forming metal itself having the dielectric oxide film impregnated with the monomer solution is used as the oxidant solution. Impregnating the dielectric oxide film impregnated with the monomer solution, spraying the oxidant solution onto the dielectric oxide film impregnated with the monomer solution, and applying the oxidant solution to the dielectric oxide film impregnated with the monomer solution. And the like.
These methods can be carried out singly or in combination of two or more.

Examples of the oxidizing agent include halides such as iodine, bromine, bromine iodide, chlorine dioxide, iodic acid, periodic acid, and chlorous acid, antimony pentafluoride, phosphorus pentachloride, phosphorus pentafluoride, and aluminum chloride. , Metal halides such as molybdenum chloride, permanganate, dichromate, chromic anhydride, ferric salts, cupric salts and other high-valent metal ion salts, sulfuric acid, nitric acid, trifluoromethane sulfuric acid Protonic acids such as oxygen compounds such as sulfur trioxide and nitrogen dioxide, hydrogen peroxide, ammonium persulfate, peroxo acids such as sodium perborate, salts of the peroxo acids, molybdophosphoric acid, tungstophosphoric acid, tungstomolybdoline Examples include heteropolyacids such as acids, salts of the heteropolyacids, and the like.
Among these, it is preferable to use a peroxosulfate such as ammonium persulfate or sodium persulfate, and more preferably ammonium persulfate.
The oxidizing agent can be used alone or in combination of two or more.

  The oxidizing agent can be used as an oxidizing agent solution. Examples of the solvent used in the solution include water and alcohol.

Examples of the solvent used for the chemical oxidative polymerization include ether compounds such as tetrahydrofuran (THF), dioxane and diethyl ether, ketone compounds such as acetone and methyl ethyl ketone compounds, dimethylformamide (DMF), acetonitrile and benzonitrile. , N-methylpyrrolidone (NMP), aprotic polar solvents such as dimethyl sulfoxide (DMSO), ester compounds such as ethyl acetate and butyl acetate, non-aromatic chlorine compounds such as chloroform and methylene chloride Nitro compounds such as nitromethane, nitroethane and nitrobenzene, alcohol compounds such as methanol, ethanol and propanol, organic acid compounds such as formic acid, acetic acid and propionic acid, acid anhydrides of the above organic acids (such as acetic anhydride) ), Water, etc. Door can be.
The solvent is preferably water, alcohol compounds, or ketone compounds.
The said solvent can use 1 type, or 2 or more types.

  When the chemical oxidative polymerization is performed, it is preferable to use a compound serving as a dopant. A conductive polymer layer (A) containing a desired dopant can be obtained by chemical oxidative polymerization in the presence of the following compound together with an oxidizing agent.

Examples of the compound serving as the dopant include halogen ions such as iodine, bromine and chlorine, hexafluoroline, hexafluoroarsenic, hexafluoroantimony, tetrafluoroboron, halide ions such as perchloric acid, methanesulfonic acid, Alkyl-substituted organic sulfonate ions such as dodecyl sulfonic acid, cyclic sulfonate ions such as camphor sulfonate ion, alkyl-substituted or unsubstituted such as benzene sulfonic acid, para-toluene sulfonic acid, dodecyl benzene sulfonic acid, benzene disulfonic acid Benzene monosulfonic acid ions, benzenesulfonic acid, paratoluenesulfonic acid, dodecylbenzenesulfonic acid, alkyl-substituted or unsubstituted benzenedisulfonic acid ions such as benzenedisulfonic acid, 2-naphthalenesulfonic acid, 1 7-Naphthalenedisulfonic acid or the like substituted with 1 to 4 sulfonic acid groups, alkyl-substituted or unsubstituted ions of naphthalene sulfonic acid, anthracene sulfonic acid ion, anthraquinone sulfonic acid ion, alkylbiphenyl sulfonic acid, biphenyl disulfonic acid, etc. Substituted or unsubstituted aromatic sulfonate ions such as alkyl-substituted or unsubstituted biphenyl sulfonate ions, polymer sulfonate ions such as polystyrene sulfonate and naphthalene sulfonate formalin condensate, bis-sulcylate boron, Examples thereof include boron compound ions such as biscatecholate boron, and heteropolyacid ions such as molybdophosphoric acid, tungstophosphoric acid, and tungstomolybdophosphoric acid.
The compound used as the dopant can be used alone or in combination of two or more.

  As a preferable compound as the dopant, the following general formula (2)

(In the formula, X ² represents a hydrogen atom or a halogen atom. X ³ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{8 to} R ₁₁ are each independently a hydrogen atom, a halogen atom, A linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched alkoxy group having 1 to 6 carbon atoms, a linear or branched halogenated alkyl group having 1 to 6 carbon atoms, An aryl group having 6 to 12 carbon atoms, a hydroxyl group, a nitro group or a cyano group).
The following general formula (3)

(In the formula, X ⁴ , X ⁵ and X ⁶ each independently represent a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R represents a hydrogen atom, a linear or branched chain having 1 to 6 carbon atoms. 1 or 2 or more of compounds represented by the following formula:

  Examples of the organic ammonium ion include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, and tetraphenylammonium ion (including various isomers). 1 type or 2 types or more can be mentioned.

  As said metal ion, 1 type, or 2 or more types, such as alkali metals, such as sodium and potassium, alkaline earth metals, such as magnesium and calcium, can be mentioned, for example.

  Examples of the linear or branched alkyl group having 1 to 6 carbon atoms include one or two of a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group (including various isomers). The above can be mentioned.

  Examples of the linear or branched alkoxy group having 1 to 6 carbon atoms include a methyloxy group, an ethyloxy group, a propyloxy group, a butyloxy group, a pentyloxy group, and a hexyloxy group (including various isomers). One type or two or more types can be mentioned.

  Examples of the linear or branched alkyl halide group having 1 to 6 carbon atoms include, for example, a fluorinated compound of the linear or branched alkyl group having 1 to 6 carbon atoms, and the above 1 to 6 carbon atoms. Or a chlorinated compound of a linear or branched alkyl group (including various isomers).

  Examples of the aryl group having 6 to 12 carbon atoms include phenyl, methylphenyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, cyclohexylphenyl, dimethylphenyl, di- One or more of propylphenyl group, naphthyl group, biphenyl group and the like (including various isomers) can be mentioned.

Specific examples of the general formula (2) include m-xylene-4-sulfonic acid, mesitylenesulfonic acid, 3-hexyltoluene-4-sulfonic acid, 3,5-dihexyltoluene-4-sulfonic acid, p- Organic sulfonic acids such as toluenesulfonic acid and p-trifluoromethylbenzenesulfonic acid,
Examples include one or more of lithium salts of the organic sulfonic acids, sodium salts of the organic sulfonic acids, alkali metal salts of the organic sulfonic acids such as potassium salts of the organic sulfonic acids, and ammonium salts of the organic sulfonic acids. be able to.
Examples of the ammonium salts of the organic sulfonic acids include, for example, ammonium salts of the organic sulfonic acids, tetramethylammonium salts of the organic sulfonic acids, tetraethylammonium salts of the organic sulfonic acids, tetrapropylammonium salts of the organic sulfonic acids, Examples thereof include tetrabutylammonium salts of organic sulfonic acids and tetraphenylammonium salts of the organic sulfonic acids.
The general formula (2) is preferably an ammonium salt of the organic sulfonic acid, an alkali metal salt of the organic sulfonic acid, or the like, more preferably tetraethylammonium p-toluenesulfonate or potassium p-trifluoromethylbenzenesulfonate. .

Specific examples of the general formula (3) include sulfophthalic acids such as 4-sulfophthalic acid, 3-methyl-4-sulfophthalic acid, 3-hexyl-4-sulfophthalic acid, 5-sulfoisophthalic acid, and 2-methyl. Sulfoisophthalic acids such as -5-sulfoisophthalic acid, 2-hexyl-5-sulfoisophthalic acid, lithium salts of the sulfophthalic acids, sodium salts of the sulfophthalic acids, alkali metals of the sulfophthalic acids such as potassium salts of the sulfophthalic acids Salt, lithium salt of isosulfophthalic acid, sodium salt of isosulfophthalic acid, alkali metal salt of isosulfophthalic acid such as potassium salt of isosulfophthalic acid, ammonium salt of sulfophthalic acid, isosulfophthalate One such as ammonium salts of phthalic acids Or it can be given two or more.
In the general formula (3), the sulfophthalic acids and ammonium salts of the sulfophthalic acids are preferable, and 4-sulfophthalic acid and triammonium 4-sulfophthalate are more preferable.

  Conductive polymer layer having high self-healing function while being highly conductive by chemical polymerization using peroxosulfate as an oxidizing agent in the presence of the compound represented by general formula (2) or general formula (3) (A) is formed, which contributes to the production of a solid electrolytic capacitor having a low leakage current and a high withstand voltage while having a high capacity and low ESR.

  The dielectric oxide film on which the conductive polymer layer (A) formed by the chemical oxidative polymerization is formed can be subjected to a re-chemical conversion treatment in a chemical conversion solution as necessary.

  The conductive polymer layer (C) is formed by applying an NMP (N-methyl-2-pyrrolidinone) solution of polyaniline. For polyaniline, a dielectric oxide film is immersed in a polyaniline NMP solution and then dried. The polyaniline NMP solution is sprayed on the surface of the dielectric oxide film to be dried, applied and dried by a doctor blade method, an appropriate resin. It can also be formed by powder coating with a binder.

  The polyaniline used for preparing the NMP solution of polyaniline is a solvent-soluble dedoped polyaniline synthesized in advance by chemical oxidative polymerization. The polyaniline obtained by chemical oxidative polymerization of aniline monomer is dedoped and dissolved in an organic solvent. It is. The chemical oxidative polymerization of the aniline monomer may be performed by oxidative polymerization of the aniline salt with an oxidizing agent in a solution in the presence of a proton acid.

  Examples of aniline salts include salts of aniline such as hydrochloric acid, sulfuric acid, perchloric acid, and borohydrofluoric acid. In addition, as oxidizing agents, persulfates such as ammonium persulfate and potassium persulfate, peroxides such as hydrogen peroxide, sodium percarbonate and sodium perborate, or potassium permanganate, potassium dichromate, chloride chloride Any oxidizing agent that oxidizes aniline such as a high-valent metal compound such as diiron can be used, but an oxidizing agent having a standard electrode potential of 0.7 V or more and less than 1.8 V is preferred. Such oxidizing agents include ferric salts, perchlorates, chlorates, chlorites, periodates, iodates, permanganates, manganese dioxide, dichromates, peroxides. Examples include sodium carbonate and sodium perborate. As the protic acid, hydrochloric acid, sulfuric acid, perchloric acid, borohydrofluoric acid, hexafluorophosphoric acid and the like are used. Capacitors obtained using polyaniline chemically oxidized and polymerized using an oxidant having a standard electrode potential higher than 1.8V, while chemical oxidative polymerization is not sufficiently performed with an oxidant having a standard oxidation potential of less than 0.7V. The change with time in the high temperature shelf life test is large.

  The chemically oxidized polymerized polyaniline is dedope when it is brought into contact with an alkaline solution such as ammonia, sodium hydroxide or an amine compound. Since the dedoped polyaniline becomes soluble in dimethylformamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, etc., it is dissolved in these solvents or a mixed solvent of these and other organic solvents and dedoped. A polyaniline solution is obtained.

  The concentration of the polyaniline solution used in the N-methyl-2-pyrrolidone solution is preferably 0.1 to 2.0 wt%, and more preferably 0.5 wt%. When it is lower than 0.1 wt%, the leakage current is not sufficiently reduced, and when it is higher than 2.0 wt%, the stability of the coating liquid is lowered. Moreover, it is preferable that the intrinsic viscosity measured in NMP solution at 30 degreeC is 0.30 g / 100 mL or more and less than 0.40 g / 100 mL. When the intrinsic viscosity is less than 0.30 g / 100 mL, since the packing density of polyaniline is small and the molecular weight is low, the initial dielectric loss and equivalent series resistance of the obtained capacitor are large, and the characteristics when left in a high-temperature atmosphere are high. The change with time also becomes large. On the other hand, at 0.40 g / 100 mL or more, the capacity impregnation rate is lowered, resulting in wasted surface area of the dielectric oxide film, and the expected capacitance cannot be obtained. In addition, since there are many voids in which no solid electrolyte is formed in the etching pits, the dielectric loss is large, and moisture enters under high humidity, resulting in deterioration of properties.

Next, the conductive polymer layer (B) will be described.
The conductive polymer layer (B) used in the present invention is formed by electrolytic polymerization using the conductive polymer layer (A) as an anode.
Specifically, the conductive polymer layer (B) is formed of the conductive polymer layer (A) in an electrolytic solution containing the monomer, the supporting electrolyte, the solvent, and the like constituting the conductive polymer described above. It can form by implementing electropolymerization as an anode.

The monomer and solvent constituting the conductive polymer used in the electrolytic polymerization are the same as those of the conductive polymer layer (A) described above.
The monomer used for the conductive polymer layer (A) and the conductive polymer layer (B
) May be the same or different from each other.

  The supporting electrolyte used in the present invention has the following general formula (1)

(In the formula, X ¹ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{1 to} R ₇ are each independently a hydrogen atom or a linear or branched alkyl having 1 to 6 carbon atoms. An organic sulfonic acid anion produced by dissociation of the compound represented by the above formula) as a dopant.

  Specific examples of the compound represented by the general formula (1) include, for example, methylanthraquinone-2-sulfonic acid, dimethylanthraquinone-2-sulfonic acid, trimethylanthraquinone-2-sulfonic acid, tetramethylanthraquinone-2-sulfone Acid, pentamethylanthraquinone-2-sulfonic acid, hexamethylanthraquinone-2-sulfonic acid, heptamethylanthraquinone-2-sulfonic acid, ethylanthraquinone-2-sulfonic acid, diethylanthraquinone-2-sulfonic acid, triethylanthraquinone-2- Sulfonic acid, tetraethylanthraquinone-2-sulfonic acid, pentaethylanthraquinone-2-sulfonic acid, hexaethylanthraquinone-2-sulfonic acid, heptaethylanthraquinone-2-sulfonic acid, butylant Quinone-2-sulfonic acid, dibutylanthraquinone-2-sulfonic acid, tributylanthraquinone-2-sulfonic acid, tetrabutylanthraquinone-2-sulfonic acid, pentabutylanthraquinone-2-sulfonic acid, hexabutylanthraquinone-2-sulfonic acid, Alkyl-substituted anthraquinone-2-sulfonic acids (including various isomers) such as heptabutylanthraquinone-2-sulfonic acid, methylethylanthraquinone-2-sulfonic acid, methylbutylanthraquinone-2-sulfonic acid, anthraquinone-2-sulfonic acid An ammonium salt of the alkyl-substituted anthraquinone-2-sulfonic acid, a tetramethylammonium salt, a tetraethylammonium salt, a tetrapropylammonium salt of the alkyl-substituted anthraquinone-2-sulfonic acid. Organic salts of alkyl-substituted anthraquinone-2-sulfonic acids such as ammonium salt, tetrabutylammonium salt, tetraphenylammonium salt, ammonium salt of the anthraquinone-2-sulfonic acid, tetramethylammonium salt of the anthraquinone-2-sulfonic acid , Organic ammonium salts of anthraquinone-2-sulfonic acids such as tetraethylammonium salt, tetrapropylammonium salt, tetrabutylammonium salt, tetraphenylammonium salt, alkyls such as sodium salts and potassium salts of the above alkyl-substituted anthraquinone-2-sulfonic acids Alkyl metal salt of substituted anthraquinone-2-sulfonic acid, alkyl-substituted anthraquinone such as magnesium salt and calcium salt of alkyl-substituted anthraquinone-2-sulfonic acid 2-sulphonic acid alkaline earth metal salt, sodium salt of anthraquinone-2-sulfonic acid, anthraquinone-2-sulphonic acid alkali metal salt such as potassium salt, magnesium salt of anthraquinone-2-sulfonic acid, calcium salt, etc. Anthraquinone-2-sulfonic acid alkaline earth metal salts and the like can be mentioned.

  The compound represented by the general formula (1) can be used alone or in combination of two or more.

In the compound represented by the general formula (1), R _{1 to} R ₇ are preferably each a hydrogen atom, and anthraquinone-2-sulfonic acid, anthraquinone-2-sulfonic acid organic ammonium salt, and anthraquinone-2-sulfone It is more preferable if it is at least one selected from the group consisting of acid metal salts.
The anthraquinone-2-sulfonic acid organic ammonium salt is more preferably a tetraalkylammonium salt.
The anthraquinone-2-sulfonic acid metal salt is more preferably an alkali metal salt.

  By selecting the supporting electrolyte, a conductive polymer having a specific stable structure is obtained when exposed to a high temperature, and by using the conductive polymer as a solid electrolyte, a heat that is significantly superior to conventional ones is obtained. A solid electrolytic capacitor having durability can be obtained.

In addition to the above, the supporting electrolyte includes lithium salts such as LiPF ₆ , LiAsF ₆ , LiClO ₄ , LiBF ₄ , sodium salts such as NaI, NaPF ₆ , NaClO ₄ , KI, KPF ₆ , KAsF ₆ , KClO _4, etc. One kind or two or more kinds of organic salts such as potassium salt, sodium toluenesulfonate, and tetrabutylammonium toluenesulfonate can be used in combination.

  As the method for the electrolytic polymerization, for example, the conductive polymer layer (A) formed by the chemical oxidation polymerization described above is immersed in the electrolytic solution, and the auxiliary electrode is connected to the conductive polymer layer (A And the like, and a method of performing electropolymerization with an external cathode using the auxiliary electrode as an anode.

  The electrolytic solution used for the electropolymerization includes a monomer that constitutes the conductive polymer, a supporting electrolyte that serves as a dopant, a solvent, and the like. What is contained at a concentration of 01 to 5 mol / L is preferable. Moreover, what contains the supporting electrolyte used as the said dopant by the density | concentration of 0.01-2 mol / L is preferable.

The solid electrolytic capacitor of the present invention can be assembled by a known method.
That is, a conductive polymer layer (A) is formed on the dielectric oxide film by chemical oxidative polymerization, and then the conductive polymer layer (B) is electrolyzed on the conductive polymer layer (A). After forming a solid electrolyte layer by polymerization, a cathode layer is formed by applying and drying a conductive paste such as carbon paste and silver paste on the solid electrolyte layer.

Next, an anode lead terminal is connected from the film forming metal, and a cathode lead terminal is connected from the cathode layer to take out an electrode to form an element. The entire element is made of an insulating resin such as epoxy resin, ceramic, metal, etc. A solid electrolytic capacitor can be obtained by sealing with an outer case or the like.
The solid electrolytic capacitor of the present invention thus obtained can be suitably used for electronic devices such as computers, control devices, communication devices, and home appliances in the electronic / electrical field.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

  <Production of capacitor element and evaluation of electrical characteristics>

[Example 1]
A 3 mm × 5 mm size etched aluminum formed foil having a dielectric oxide film formed on the surface was dried in a 105 ° C. dryer for 10 minutes. This was left to stand on an 18 ° C. thermoplate for 10 minutes.
Next, 4 μl of a monomer solution (mixture of 3 g of pyrrole, 5 g of ethanol and 18.4 g of water) cooled to 18 ° C. was dropped onto the etched aluminum formed foil, and allowed to stand for 1 minute.
Furthermore, 12 [mu] l of an oxidizing agent solution [mixed solution of 5.6 mmol of tetraethylammonium paratoluenesulfonate (PTS-TEA), 1.56 g of ammonium peroxodisulfate and 10.63 g of water] is dropped on the foil and left to stand for 10 minutes. Thus, a conductive polymer layer (A) formed by chemical oxidative polymerization was formed. This was washed with pure water and dried in a dryer at 105 ° C. for 10 minutes.

  Next, the conductive polymer layer (A) is immersed in an electrolytic solution (mixed solution of 4.67 mmol of anthraquinone-2-sulfonic acid, 0.6 g of pyrrole and 45.8 g of water), and the etched aluminum formed foil Is used as an anode, the current value is fixed at 0.4 mA, and electropolymerization is performed to form a conductive polymer layer (B), whereby a solid is formed on the dielectric oxide film provided on the surface of the etched aluminum formed foil. An electrolyte layer was formed.

Next, a carbon paste and a silver paste were sequentially applied to the conductive polymer layer (B) and dried to complete a total of 20 capacitor elements.
For these 20 capacitor elements, capacitance (Cs) at 120 Hz, loss factor (tan δ × 100), capacitance (Cs) at 100 kHz, and equivalent series resistance (ESR) were measured as initial characteristics.
In addition, a thermal durability test was performed by leaving in the atmosphere at 155 ° C., and the characteristics were evaluated after a predetermined time. The results are shown in Tables 1, 3 and 6 and FIGS.
The capacitor element used in the thermal durability test was not sealed with an insulating resin or the like.

[Example 2]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electropolymerization was performed using a mixed solution of 4.67 mmol of sodium anthraquinone-2-sulfonate, 0.6 g of pyrrole, and 45.8 g of water as the electrolytic solution to form a conductive polymer layer (B).
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.

[Example 3]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electropolymerization was performed using a mixed solution of 4.67 mmol of tetraethylammonium anthraquinone-2-sulfonate, 0.6 g of pyrrole, and 45.8 g of water as the electrolytic solution to form a conductive polymer layer (B).
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.

[Example 4]
Twenty capacitor elements were obtained in the same manner as in Example 2 except that the method for producing the conductive polymer layer (A) was changed to the following method.
That is, chemical oxidation polymerization was performed using a mixed solution of 5.6 mmol of 4-sulfophthalic acid, 1.56 g of ammonium peroxodisulfate, and 10.63 g of water as an oxidant solution to form the conductive polymer layer (A).
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.
Compared with Examples 1 to 3, ESR showed a remarkably small value.

[Example 5]
Twenty capacitor elements were obtained in the same manner as in Example 2 except that the method for producing the conductive polymer layer (A) was changed to the following method.
That is, chemical oxidative polymerization is performed using 5.6 mmol triammonium 4-sulfophthalate, 1.56 g ammonium peroxodisulfate, 10.63 g water and 3.42 g ethanol as an oxidant solution, and the conductive polymer layer (A) was formed.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.
Compared with Examples 1 to 3, ESR showed a remarkably small value.

[Example 6]
Twenty capacitor elements were obtained in the same manner as in Example 2 except that the method for producing the conductive polymer layer (A) was changed to the following method.
That is, chemical oxidative polymerization was performed using a mixed liquid of 5.6 mmol potassium trifluoromethylbenzenesulfonate, 1.56 g ammonium peroxodisulfate and 10.63 g water as an oxidant liquid, and the conductive polymer layer (A) was formed. Formed.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.
Compared with Examples 1-3, it confirmed that the electrostatic capacitance Cs increased.

[Example 7]
Twenty capacitor elements were obtained in the same manner as in Example 2 except that the method for producing the conductive polymer layer (A) was changed to the following method.
That is, chemical oxidation polymerization was performed using a mixed solution of sodium anthraquinone-2-sulfonate 5.6 mmol, ammonium peroxodisulfate 1.56 g and water 10.63 g as an oxidant solution, and the conductive polymer layer (A) was formed. Formed.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.
Compared with Examples 1-3, it confirmed that the electrostatic capacitance Cs increased.

[Example 8]
Twenty capacitor elements were obtained in the same manner as in Example 2 except that the method for producing the conductive polymer layer (A) was changed to the following method.
That is, the conductive polymer layer (A) was formed by performing chemical oxidative polymerization using a mixed liquid of sodium alkylnaphthalenesulfonate 5.6 mmol, ammonium peroxodisulfate 1.56 g and water 10.63 g as an oxidant liquid. .
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.

[Example 9]
The conductive polymer layer (C) is first provided on the surface of the dielectric oxide film by the following method, and then the capacitor element is manufactured in the same manner as in Example 1 except that the capacitor element is manufactured by the method described in Example 1. Produced.

  First, polyaniline was synthesized by chemical oxidative polymerization. In a 200 mL glass reaction vessel, take 30 mL of an aqueous solution containing 4.7 g of aniline and 2.5 g of concentrated sulfuric acid, add 30 mL of an aqueous solution containing 3.2 g of potassium permanganate dropwise over 2 hours, and then react for 3 hours to perform chemical oxidative polymerization. To obtain polyaniline. After adding 50 mL of 25 wt% aqueous ammonia and stirring for 3 hours, the mixture was centrifuged and washed with water to obtain a dedoped polyaniline powder.

  The polyaniline powder thus obtained was dissolved in N-methyl-2-pyrrolidone to prepare a 0.5 wt% soluble polyaniline solution.

  The etched aluminum formed foil cut to a predetermined size is dipped in the polyaniline solution for 10 minutes, then pulled up, dried in an air dryer at 105 ° C. for 10 minutes, and a conductive polymer layer (C ) Was formed.

  The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.

[Example 10]
In Example 9, a solid electrolyte was formed on the dielectric oxide film in the same manner as in Example 9 except that the capacitor element was produced using the combination of the conductive polymer layers (A) and (B) in Example 2. Electrodes were formed using conductive carbon and silver paste sequentially.

  The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.

[Example 11]
In Example 9, a solid electrolyte was formed on the dielectric oxide film in the same manner as in Example 8 except that the capacitor element was produced using the combination of the conductive polymer layers (A) and (B) in Example 3. Electrodes were formed using conductive carbon and silver paste sequentially.

  The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1, 3 and 6 and FIGS.

[Comparative Example 1]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization was performed using a mixed solution of 4.67 mmol of disodium anthraquinone-2,7-disulfonate, 0.6 g of pyrrole, and 45.8 g of water as an electrolytic solution to form a conductive polymer layer (B). .
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 4 and 7, and FIGS.
Compared with Examples 1-7, the result which is largely inferior to thermal durability was shown.

[Comparative Example 2]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization was performed using a mixed solution of 4.67 mmol of naphthalene-2,7-disulfonic acid disodium, 0.6 g of pyrrole and 45.8 g of water as an electrolytic solution to form a conductive polymer layer (B). .
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 4 and 7, and FIGS.
Compared with Examples 1-7, the result which is largely inferior to thermal durability was shown.

[Comparative Example 3]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electropolymerization was performed using a mixed solution of 4.67 mmol of 4,4-biphenyldisulfonic acid, 0.6 g of pyrrole, and 45.8 g of water in the electrolytic polymerization solution to form a conductive polymer layer (B).
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 4 and 7, and FIGS.
Compared with Examples 1-7, the result which is largely inferior to thermal durability was shown.

[Comparative Example 4]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electropolymerization was performed using a mixed solution of 4.67 mmol of alkylnaphthalenesulfonic acid Na, 0.6 g of pyrrole and 45.8 g of water as an electrolytic solution to form a conductive polymer layer.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 4 and 7, and FIGS.
Compared with Examples 1-7, the result which is largely inferior to thermal durability was shown.

[Comparative Example 5]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization was performed using a mixed solution of 4.67 (mmol) of 4-sulfophthalic acid, 0.9 g of pyrrole, and 45.8 g of water as an electrolytic solution, thereby forming a conductive polymer layer.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 4 and 7, and FIGS.
Compared with Examples 1-7, the result which is largely inferior to thermal durability was shown.

[Comparative Example 6]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electropolymerization was performed using a mixed solution of 4.67 mmol of sodium anthraquinone-1-sulfonate, 0.6 g of pyrrole, and 45.8 g of water as the electrolytic solution to form a conductive polymer layer.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 4 and 7, and FIGS.
Compared to Examples 1 to 7, the initial characteristics and thermal durability of the capacitors were greatly inferior.

[Comparative Example 7]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electropolymerization was performed using a mixed solution of 4.67 mmol of disodium anthraquinone-2,6-disulfonate, 0.6 g of pyrrole and 45.8 g of water as an electrolytic solution to form a conductive polymer layer (B). .
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 4 and 7, and FIGS.
Compared with Examples 1-7, the result which is largely inferior to thermal durability was shown.

[Comparative Example 8]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization was performed using a mixed solution of 4.67 mmol of sodium n-dodecylbenzenesulfonate, 0.6 g of pyrrole, and 45.8 g of water as the electrolytic solution to form a conductive polymer layer (B).
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 4 and 7, and FIGS.
Compared with Examples 1-7, the result which is largely inferior to thermal durability was shown.

[Comparative Example 9]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization is performed using a mixed solution of 4.67 mmol of sodium 1,4-naphthoquinone-2-sulfonate, 0.6 g of pyrrole, and 45.8 g of water in the electrolytic solution to form a conductive polymer layer (B). did.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1-7, the result which is largely inferior to thermal durability was shown.

[Comparative Example 10]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization is performed using a mixed solution of 3.67 mmol of 3,4-dihydroxyanthraquinone-2-sulfonic acid, 0.6 g of pyrrole and 45.8 g of water in the electrolytic solution to form a conductive polymer layer (B). did.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1-7, the result which is largely inferior to thermal durability was shown.

[Comparative Example 11]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization was performed using a mixed solution of 4.67 mmol of sodium 9,10-dimethoxyanthracene-2-sulfonate, 0.6 g of pyrrole, and 45.8 g of water as the electrolytic solution, and the conductive polymer layer (B) was formed. Formed.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1-7, the rate of change of ESR was particularly large and the results were greatly inferior in thermal durability.

[Comparative Example 12]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization was performed using a mixed solution of 4.67 mmol of sodium 1-naphthalenesulfonate, 0.6 g of pyrrole, and 45.8 g of water as an electrolytic solution, thereby forming a conductive polymer layer (B).
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1-7, the rate of change of ESR was particularly large and the results were greatly inferior in thermal durability.

[Comparative Example 13]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization was carried out using a mixed solution of 4.67 mmol of sodium 1-amino-4-bromoanthraquinone-2-sulfonate, 0.6 g of pyrrole and 45.8 g of water as the electrolytic solution, and the conductive polymer layer (B ) Was formed.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1-7, the rate of change of ESR was particularly large and the results were greatly inferior in thermal durability.

[Comparative Example 14]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization was performed using a mixed solution of 4.67 mmol of sodium 4,8-diamino-1,5-dihydroxyanthraquinone-2-sulfonate, 0.6 g of pyrrole and 45.8 g of water as the electrolytic solution. A molecular layer (B) was formed.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1 to 7, the results were greatly inferior in thermal durability.

[Comparative Example 15]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electropolymerization was performed using a mixed solution of 4.67 mmol of anthraquinone-1,5-disulfonic acid disodium salt, 0.6 g of pyrrole and 45.8 g of water as an electrolytic solution to form a conductive polymer layer (B). .
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1 to 7, the results were greatly inferior in thermal durability.

[Comparative Example 16]
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer layer (B) was changed to the following method.
That is, electrolytic polymerization was performed using a mixed solution of 4.67 mmol of disodium anthraquinone-1,8-disulfonate, 0.6 g of pyrrole, and 45.8 g of water as an electrolytic solution to form a conductive polymer layer (B). .
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1 to 7, the results were greatly inferior in thermal durability.

[Comparative Example 17]
In the case of Example 7, only the conductive polymer layer (A) was formed, and the conductive polymer layer (B
) Was not formed, and 20 capacitor elements were obtained in the same manner as in Example 7.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1 to 7, the results were greatly inferior in thermal durability.

[Comparative Example 18]
In the case of Example 4, only the conductive polymer layer (A) is formed, and the conductive polymer layer (B
) Was not formed, and 20 capacitor elements were obtained in the same manner as in Example 4.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1 to 7, the results were greatly inferior in thermal durability.

[Comparative Example 19]
In the case of Example 1, only the conductive polymer layer (A) is formed, and the conductive polymer layer (B
) Was not formed, and 20 capacitor elements were obtained in the same manner as in Example 1.
The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.
Compared with Examples 1 to 7, the results were greatly inferior in thermal durability.

[Comparative Example 20]
A capacitor element is formed in the same manner as in Example 1 except that the conductive polymer layer (C) is first provided on the surface of the dielectric oxide film by the following method, and then a capacitor element is manufactured by the method described in Comparative Example 4. Created.

  First, polyaniline was synthesized by chemical oxidative polymerization. In a 200 mL glass reaction vessel, take 30 mL of an aqueous solution containing 4.7 g of aniline and 2.5 g of concentrated sulfuric acid, add 30 mL of an aqueous solution containing 3.2 g of potassium permanganate dropwise over 2 hours, and then react for 3 hours to perform chemical oxidative polymerization. To obtain polyaniline. After adding 50 mL of 25 wt% aqueous ammonia and stirring for 3 hours, the mixture was centrifuged and washed with water to obtain a dedoped polyaniline powder.

  The polyaniline powder thus obtained was dissolved in N-methyl-2-pyrrolidone to prepare a 0.5 wt% soluble polyaniline solution.

  The etched aluminum formed foil cut to a predetermined size is dipped in the polyaniline solution for 10 minutes, then pulled up, dried in an air dryer at 105 ° C. for 10 minutes, and a conductive polymer layer (C ) Was formed.

  The characteristics of the capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 2, 5 and 8, and FIGS.

  The solid electrolytic capacitor containing the compound represented by the general formula (1) in the conductive polymer layer (B) is a solid electrolytic capacitor regardless of the type of dopant used in the conductive polymer layer (A). It was confirmed that the heat durability and the like were greatly improved.

  Tables 2 and 3 above show changes in Cs (120 Hz) with respect to the test time in the heat resistance test of the capacitor element in the example.

  Tables 4 and 5 above show changes in Cs (120 Hz) with respect to the test time in the heat resistance test of the capacitor element in the comparative example.

  Table 6 shows the change in ESR (100 kHz) with respect to the test time in the heat resistance test of the capacitor element in the example.

  The said Tables 7 and 8 show the change of ESR (100 kHz) with respect to test time in the heat resistance test of the capacitor element in the comparative example.

  <Evaluation of capacitor leakage current and withstand voltage>

The capacitor elements obtained in Examples 1, 4, 7, 8, 9 and Comparative Examples 4 and 20 were molded with epoxy resin, a DC voltage of 4 V was applied, and an environment of 65 ° C. RH and 85 ° C. was applied. Time aging treatment was performed, and the leakage current before and after the aging treatment was examined.
In addition, a withstand voltage test was performed in which the forward voltage applied to the capacitor after the aging treatment was increased from 0 V at a rate of 0.1 V per 30 seconds, and the voltage at which the leakage current of the element was 100 mA was defined as the withstand voltage. The results are shown in Table 6.

  When the conductive polymer layer (C) made of polyaniline is formed on the surface of the dielectric oxide film, and then the conductive polymer layer (A) and the conductive polymer layer (B) are sequentially formed, the epoxy resin sealing The leakage current reduction effect was confirmed in the aging process after stopping, and the withstand voltage of the device was also improved. The conductive polymer layer (C) is unnecessary when the dielectric oxide film has high quality and little damage. However, when the damage is large and aging treatment is required, the conductive polymer layer (C) is used. In addition, it is possible to provide an element that is compatible with low ESR, high heat resistance, low leakage current, and high withstand voltage and is excellent in reliability.

  <Evaluation with XPS>

  The capacitor elements produced in Examples 2, 4, 5 and Comparative Examples 1, 4, 6 were subjected to X-ray photoelectron spectroscopy analysis before and after the thermal durability test, and the results are shown in FIGS. 7 to 18 as N1sXPS spectra. The chemical state ratios of N1s are shown in Table 10, and the abundance ratio of nitrogen and sulfur element [the abundance ratio of sulfur element when nitrogen is 1 (relative value)] is shown in Table 11, respectively.

After 110 hours of thermal durability test, in Comparative Examples 1, 4 and 6, the peak intensity ratio near 401.5 eV attributed to —NH ⁺ X ⁻ — in the N1s spectrum decreases, while Examples 2, 4 and 6 5 shows that there is no such change.
The electropolymerized polypyrrole film, which is the conductive polymer layer (B), is doped with anthraquinone-2-sulfonic acid Na and doped with anthraquinone-2,7-disulfonic acid Na and alkylnaphthalenesulfonic acid Na. Compared to the state, it is extremely thermally stable. That is, a conductive polymer having excellent heat durability is formed.

  In addition, from the table, sodium anthraquinone-2-sulfonate as a dopant at the time of electrolytic polymerization used in the present invention is compared with sodium anthraquinone-1-sulfonate that is a dopant at the time of electrolytic polymerization in which only the position of the sulfone group is different. It is excellent in that the dope ratio into the polypyrrole film is high.

By the way, about the presence state (chemical state, abundance) of the dopant molecule in the conductive polymer, an analysis method by X-ray photoelectron spectroscopy analysis has been reported (reference document Conductive Polymers Vol. 3 p. 134).
X-ray photoelectron spectroscopy is an analytical method in which a sample is irradiated with X-rays in an ultra-high vacuum and the kinetic energy and number of photoelectrons emitted from the inner shell of the atoms constituting the sample are measured with an energy analyzer. is there.

Usually, the electrons that make up an atom are bound to a certain intensity from the nucleus, so the kinetic energy of the photoelectrons emitted when struck with X-rays is
(Excitation light energy)-(Binding energy)
It becomes. However, a slight change (chemical shift) in the kinetic energy value can be confirmed in comparison with the free state, particularly in a state where the atoms are subjected to other constraints such as forming a compound or a crystal lattice.

  In X-ray photoelectron spectroscopy, the amount of this chemical shift differs depending on the state of the atom where it is placed, so this phenomenon can be used to obtain information on the chemical state of each element. The abundance ratio of various elements can be specified.

When polypyrrole is used as the solid electrolyte of the solid electrolytic capacitor, the peak intensity of the X-ray photoelectron spectroscopy attributed to the chemical state of the solid electrolyte —NH ⁺ X ⁻ — shows a strong correlation with the durability of the capacitor.
That is, before and after the heat resistance test that was left in the atmosphere at 155 ° C. for 110 hours, the decrease rate V of the chemical state —NH ⁺ X ⁻ — in the solid electrolyte defined by the following formula (4) was 0.2 (% / h) or less. It has been found that the solid electrolytic capacitor is extremely excellent in thermal durability.

Actually, with respect to Examples 2, 4, and 5 and Comparative Examples 1 and 4, the peak intensity decrease rate near 401.5 eV attributed to the chemical state -NH ⁺ X ^-- before and after the heat test, The results are summarized in Table 12 for the capacitance Cs (120 Hz) decrease rate and ESR (100 kHz) increase rate.

Here, the chemical state -NH ⁺ X ^-- decrease rate, capacitance Cs (120 Hz) decrease rate, and ESR (100 kHz) increase rate are defined by the following equations, respectively.

From the table, it was suggested that the decrease rate of the chemical state -NH ⁺ X ^-- before and after the heat resistance test, the capacitance Cs (120 Hz) decrease rate, and the ESR (100 kHz) increase rate are in a proportional relationship.

In the table, especially in the Examples 2, 4 and 5 using sodium anthraquinone-2-sulfonic acid to electrolytic polymerization dopant, before and after the heat resistance test of 110 hours in 155 ° C. air, chemical state ^-NH + X ^- - of When the decrease rate is 0.2 (% / h) or less, the capacitance Cs (120 Hz) decrease rate is 0.17 (% / h) or less, and the ESR (100 kHz) increase rate is 4.0 (% / h). ) The following excellent thermal durability was exhibited.

It is the graph which plotted Cs (120 Hz) with respect to test time in the heat resistance test of the capacitor | condenser element in an Example. It is the graph which plotted Cs (120 Hz) with respect to test time in the heat resistance test of the capacitor | condenser element in a comparative example. It is the graph which plotted Cs (120 Hz) with respect to test time in the heat resistance test of the capacitor | condenser element in a comparative example. It is the graph which plotted ESR (100 kHz) with respect to test time in the heat resistance test of the capacitor | condenser element in an Example. It is the graph which plotted ESR (100 kHz) with respect to test time in the heat resistance test of the capacitor | condenser element in a comparative example. It is the graph which plotted ESR (100 kHz) with respect to test time in the heat resistance test of the capacitor | condenser element in a comparative example. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis before the heat test of the capacitor | condenser element of Example 2. FIG. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis after the heat test of the capacitor | condenser element of Example 2. FIG. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis before the heat test of the capacitor | condenser element of Example 4. FIG. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis after the heat test of the capacitor | condenser element of Example 4. FIG. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis before the heat test of the capacitor | condenser element of Example 5. FIG. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis after the heat resistance test of the capacitor | condenser element of Example 5. FIG. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis before the heat test of the capacitor | condenser element of the comparative example 1. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis after the heat test of the capacitor | condenser element of the comparative example 1. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis before the heat test of the capacitor | condenser element of the comparative example 4. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis after the heat test of the capacitor | condenser element of the comparative example 4. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis before the heat test of the capacitor | condenser element of the comparative example 6. It is a N1sXPS spectrum figure by the X-ray photoelectron spectroscopy analysis after the heat test of the capacitor | condenser element of the comparative example 6.

Explanation of symbols

1 Peak corresponding to N1s 2 Peak 1 due to influence of dopant
3 Peak 2 due to dopant effects
4 Peak 3 due to dopant effect
5 Peak 4 due to dopant effect

Claims (10)

A solid electrolytic capacitor having a solid electrolyte layer on a dielectric oxide film provided on a film-forming metal surface, wherein the solid electrolyte layer includes a conductive polymer layer (A) formed by chemical oxidative polymerization and A conductive polymer layer (B) formed by electrolytic polymerization using the conductive polymer layer (A) as an anode, and the conductive polymer layer (B) has the following general formula: (1)

(In the formula, X ¹ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{1 to} R ₇ are each independently a hydrogen atom or a linear or branched alkyl having 1 to 6 carbon atoms. A solid electrolytic capacitor comprising an organic sulfonate anion generated by dissociation of an organic sulfonate represented by the formula:   The organic sulfonate represented by the general formula (1) is at least one selected from the group consisting of anthraquinone-2-sulfonic acid, anthraquinone-2-sulfonic acid organic ammonium salt, and an anthraquinone-2-sulfonic acid alkali metal salt. The solid electrolytic capacitor according to claim 1, wherein the solid electrolytic capacitor is one. The conductive polymer layer (A) has the following general formula (2),

(In the formula, X ² represents a hydrogen atom or a halogen atom. X ³ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{8 to} R ₁₁ are each independently a hydrogen atom, a halogen atom, A linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched alkoxy group having 1 to 6 carbon atoms, a linear or branched halogenated alkyl group having 1 to 6 carbon atoms, Represents an aryl group having 6 to 12 carbon atoms, a hydroxyl group, a nitro group, or a cyano group), or
The following general formula (3)

(In the formula, X ⁴ , X ⁵ and X ⁶ each independently represent a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R represents a hydrogen atom, a linear or branched chain having 1 to 6 carbon atoms. 3. The solid electrolytic capacitor according to claim 1, comprising an organic sulfonate anion generated by dissociation of an organic sulfonate represented by formula (1) as a dopant.   The solid electrolytic capacitor according to claim 1, wherein the conductive polymer layer (A) and the conductive polymer layer (B) each contain polypyrrole. Between the dielectric oxide film and the conductive polymer layer (A),
5. The solid electrolytic capacitor according to claim 1, further comprising a conductive polymer layer (C) made of polyaniline. Forming a dielectric oxide film on the film-forming metal surface;
Forming a conductive polymer layer (A) on the dielectric oxide film by chemical oxidative polymerization;
Forming a conductive polymer layer (B) on the conductive polymer layer (A) by electrolytic polymerization;
A method for producing a solid electrolytic capacitor having
The chemical oxidative polymerization is represented by the following general formula (2)

(In the formula, X ² represents a hydrogen atom or a halogen atom. X ³ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{8 to} R ₁₁ are each independently a hydrogen atom, a halogen atom, A linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched alkoxy group having 1 to 6 carbon atoms, a linear or branched halogenated alkyl group having 1 to 6 carbon atoms, A compound having 6 to 12 carbon atoms, a hydroxyl group, a nitro group or a cyano group), or the following general formula (3)

(In the formula, X ⁴ , X ⁵ and X ⁶ each independently represent a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R represents a hydrogen atom, a linear or branched chain having 1 to 6 carbon atoms. In the presence of a compound represented by the following formula:
The electrolytic polymerization is represented by the following general formula (1)

(In the formula, X ¹ represents a hydrogen ion, an ammonium ion, an organic ammonium ion or a metal ion. R _{1 to} R ₇ are each independently a hydrogen atom or a linear or branched alkyl having 1 to 6 carbon atoms. The method for producing a solid electrolytic capacitor is carried out in the presence of a compound represented by:   The compound represented by the general formula (1) is at least one selected from the group consisting of anthraquinone-2-sulfonic acid, anthraquinone-2-sulfonic acid organic ammonium salt, and an anthraquinone-2-sulfonic acid alkali metal salt. The manufacturing method of the solid electrolytic capacitor of Claim 6 characterized by the above-mentioned. In the manufacturing method of the solid electrolytic capacitor of Claim 6 or 7,
Forming a dielectric oxide film on the film-forming metal surface;
Forming a conductive polymer layer (C) made of polyaniline on the dielectric oxide film;
Forming a conductive polymer layer (A) on the conductive polymer layer (C) by chemical oxidative polymerization;
Forming a conductive polymer layer (B) on the conductive polymer layer (A) by electrolytic polymerization;
A method for producing a solid electrolytic capacitor, comprising:   The method for producing a solid electrolytic capacitor according to claim 8, wherein the conductive polymer layer (C) is formed by applying and drying an NMP solution of polyaniline.   The electronic device provided with the solid electrolytic capacitor in any one of Claims 1-5.

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