阅读说明：本技术 电解电容器用添加剂、导电性高分子分散液、电解液和电解电容器 (Additive for electrolytic capacitor, conductive polymer dispersion, electrolytic solution, and electrolytic capacitor ) 是由 赤泽庆彦 田边史行 内桥贤吾 芝隆宏 向井孝夫 于 2018-08-02 设计创作，主要内容包括：本发明为一种电解电容器用添加剂,其用于包括固体电解质层的电解电容器,所述电解电容器用添加剂含有具有亲水性基的聚合体(A),聚合体(A)的亲水性基的浓度基于聚合体(A)的重量而为18毫摩尔/克以下,聚合体(A)的溶解度参数为12(cal/cm<Sup>3</Sup>)<Sup>1/2</Sup>以上。(The present invention is an additive for electrolytic capacitors, which is used for an electrolytic capacitor comprising a solid electrolyte layer, said additive for electrolytic capacitors containing a polymer (A) having a hydrophilic group, the concentration of the hydrophilic group of the polymer (A) being 18 mmol/g or less based on the weight of the polymer (A), and the solubility parameter of the polymer (A) being 12 (cal/cm) 3 ) 1/2 The above.)

1. An additive for electrolytic capacitors, for use in an electrolytic capacitor comprising a solid electrolyte layer, which additive for electrolytic capacitors contains a polymer (A) having a hydrophilic group, the concentration of the hydrophilic group of the polymer (A) being 18 mmol/g or less based on the weight of the polymer (A), and the solubility parameter of the polymer (A) being 12 (cal/cm)³)^1/2The above.

2. The additive for electrolytic capacitors as claimed in claim 1, wherein the hydrophilic group is at least one group selected from the group consisting of a hydroxyl group, an acidic group, a basic group and an oxyalkylene group having 2 to 3 carbon atoms.

3. The additive for electrolytic capacitors as claimed in claim 1 or 2, wherein the polymer (A) is a polymer having, as a constituent monomer, an ethylenically unsaturated monomer (a) having the hydrophilic group.

4. The additive for electrolytic capacitors as claimed in claim 3, wherein the ethylenically unsaturated monomer (a) having a hydrophilic group is at least one selected from the group consisting of a (meth) acrylic monomer having a hydroxyl group, a (meth) acrylic monomer having an acidic group, a (meth) acrylic monomer having a basic group, and an alkyl ether of an alkylene oxide adduct to the (meth) acrylic monomer having a hydroxyl group,

the alkylene oxide added to the (meth) acrylic acid monomer having a hydroxyl group is an alkylene oxide having 2 to 3 carbon atoms,

the (meth) acrylic monomer having a hydroxyl group is at least one selected from the group consisting of a hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms, a lactone adduct to the hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms, and an alkylene oxide adduct to the hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms,

the (meth) acrylic monomer having an acidic group is at least one selected from the group consisting of an acid anhydride adduct to the (meth) acrylic monomer having a hydroxyl group, a lactone adduct to (meth) acrylic acid, and (meth) acrylic acid,

the (meth) acrylic monomer having a basic group is at least one selected from the group consisting of (meth) acrylamide having 3 to 20 carbon atoms and aminoalkyl (meth) acrylate having 4 to 12 carbon atoms.

5. The additive for electrolytic capacitors as claimed in claim 3 or 4, wherein the proportion of the total weight of the ethylenically unsaturated monomers (a) having a hydrophilic group constituting the polymer (A) is from 50 to 100% by weight, based on the weight of all the monomers constituting the polymer (A).

6. The additive for electrolytic capacitors as claimed in any one of claims 1 to 5, wherein the number average molecular weight of the polymer (A) is from 1,000 to 500,000.

7. The additive for electrolytic capacitors as claimed in any one of claims 1 to 6, wherein the polymer (A) has a glass transition point of-100 ℃ to 80 ℃.

8. An electroconductive polymer dispersion liquid containing the additive for electrolytic capacitors as claimed in any one of claims 1 to 7.

9. An electrolytic solution containing the additive for electrolytic capacitors as claimed in any one of claims 1 to 7.

10. An electrolytic capacitor comprising the additive for electrolytic capacitors as claimed in any one of claims 1 to 7.

Technical Field

The present invention relates to an additive for electrolytic capacitors, a conductive polymer dispersion, an electrolytic solution, and an electrolytic capacitor.

Background

In recent years, as electronic products have been miniaturized, high-frequency capacitors having a small size and a large capacity have been demanded. As such a capacitor, an electrolytic capacitor having a small equivalent series resistance (hereinafter, abbreviated as esr) and excellent frequency characteristics has been developed. An electrolytic capacitor includes: an anode foil containing aluminum, tantalum, or the like, a dielectric layer containing aluminum oxide, tantalum oxide, or the like formed on the anode foil, and a cathode foil. Among them, an electrolytic capacitor in which a solid electrolyte layer containing a conductive polymer as a cathode material is formed on a dielectric layer is called a solid electrolytic capacitor.

Since the solid electrolytic capacitor uses a conductive polymer, it can achieve a lower ESR than an electrolytic capacitor using an electrolytic solution.

However, the solid electrolytic capacitor has a problem that the guaranteed voltage cannot be increased because it does not contain a substance such as an electrolytic solution which is responsible for repairing the dielectric body, and thus the leakage current is large and the withstand voltage is low.

In order to solve the above problem, patent document 1 discloses a technique for suppressing a leakage current by covering a dielectric surface with polyvinyl alcohol. Patent document 2 discloses a technique for improving withstand voltage by introducing a copolymer of acrylic acid and vinylphenol into a solid electrolyte layer. However, these techniques are insufficient in the effect of reducing leakage current and improving withstand voltage.

In addition, demands for higher reliability are increasing in AV devices and automotive electrical devices. Therefore, in addition to the performance such as reduction of ESR, improvement of low leakage current and short-circuit resistance is also required in the solid electrolytic capacitor.

In response to such a demand, a so-called hybrid electrolytic capacitor is proposed: in addition to using a solid electrolyte such as a conductive polymer such as polypyrrole, polyaniline, or polythiophene as an electrolyte material, an electrolytic solution having an excellent repairing effect on a defect portion of an anodic oxide film as a dielectric is also used (for example, patent documents 3 and 4).

In these hybrid electrolytic capacitors, the electrolyte solution enters the gaps between the solid electrolytes of the conductive polymers, and the degree of contact between the dielectric oxide film and the electrolyte is increased. Therefore, the capacitance is increased, the ESR is reduced, the defective portion of the dielectric oxide film can be repaired by the action of the electrolytic solution, the leak current is small, and short-circuiting can be suppressed.

However, the conventional hybrid electrolytic capacitor is insufficient in suppressing the leakage current, particularly in a high-temperature environment.

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to reduce leakage current and improve withstand voltage of an electrolytic capacitor including a solid electrolyte layer.

Means for solving the problems

The present inventors have conducted studies to achieve the above object, and as a result, have reached the present invention.

That is, the present invention is an additive for electrolytic capacitors, which is used for an electrolytic capacitor comprising a solid electrolyte layer, the additive for electrolytic capacitors containing a polymer (A) having a hydrophilic group, the concentration of the hydrophilic group of the polymer (A) being 18 mmol/g or less based on the weight of the polymer (A), and the solubility parameter of the polymer (A) being 12 (cal/cm)³)^1/2The above. The present invention also provides a conductive polymer dispersion containing the additive for electrolytic capacitors, an electrolytic solution containing the additive for electrolytic capacitors, and an electrolytic capacitor containing the additive for electrolytic capacitors.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, an additive for electrolytic capacitors which has a small leak current and an excellent withstand voltage can be provided.

Detailed Description

The additive for electrolytic capacitors of the present invention is an additive for electrolytic capacitors as follows: which is used for an electrolytic capacitor comprising a solid electrolyte layer and contains a polymer (A) having a hydrophilic group, the concentration of the hydrophilic group of the polymer (A) being 18 mmol/g or less based on the weight of the polymer (A), and the solubility parameter of the polymer (A) being 12 (cal/cm)³)^1/2The above.

First, the polymer (A) having a hydrophilic group will be described.

The hydrophilic group is not particularly limited, and examples thereof include a hydroxyl group, an acidic group, a basic group, and an oxyalkylene group having 2 to 3 carbon atoms. Examples of the acidic group include: carboxyl, sulfonic acid, phosphonic acid, and the like. Examples of the basic group include an amino group and an ammonium group. Examples of the oxyalkylene group having 2 to 3 carbon atoms include an oxyethylene group, a 1, 2-oxypropylene group and a 1, 3-oxypropylene group.

Among these hydrophilic groups, a hydroxyl group and an acidic group are preferable, and a hydroxyl group is more preferable, from the viewpoint of leakage current.

The concentration of the hydrophilic group in the polymer (A) having a hydrophilic group is 18 mmol/g or less based on the weight of the polymer (A). The upper limit is preferably 13 mmol/g, and more preferably 10 mmol/g, and the lower limit is preferably 2 mmol/g, and more preferably 4 mmol/g. When the concentration of the hydrophilic group in the polymer (A) exceeds 18 mmol/g, the intermolecular force becomes strong and precipitates at a low temperature, so that there is a problem that the low-temperature characteristics of the capacitor are deteriorated.

The concentration of the hydrophilic group in the polymer (A) can be adjusted by the selection of the constituent monomers and the weight ratio.

The concentration of the hydrophilic group in the polymer (A) is defined by the amount (number of moles) of the hydrophilic group-containing substance contained in 1g of the polymer (A). The concentration of the hydrophilic group in the polymer (a) is measured by the following method.

In the case where the hydrophilic group is a hydroxyl group, the concentration of the hydrophilic group of the polymer (a) is determined by using Japanese Industrial Standards (JIS) K0700: 1992, the hydroxyl value was determined by the method described below, and the value was calculated by the following calculation formula.

The concentration (mmol/g) of the hydrophilic group of the polymer (a) is hydroxyl value (mgKOH/g)/56.1

When the hydrophilic group is an acidic group, the concentration of the hydrophilic group in the polymer (a) is determined by JIS K0700: 1992, the acid value was determined by the method described in the following equation.

The concentration (mmol/g) of the hydrophilic group of the polymer (a) is equal to the acid value (mgKOH/g)/56.1

In the case where the hydrophilic group is a base, the concentration of the hydrophilic group of the polymer (a) is determined by JIS K2501: the alkali value was obtained by the method described in 2003 and calculated by the following calculation formula.

The concentration (mmol/g) of the hydrophilic group of the polymer (a) is equal to the base number/56.1

When the hydrophilic group is an oxyalkylene group having 2 to 3 carbon atoms, the concentration of the hydrophilic group in the polymer (A) can be determined by the following method.

The polymer (A) was hydrolyzed in a 1mol/l aqueous solution of sodium hydroxide at 100 ℃ for 2 hours to obtain a solution in which the oxyalkylene group-containing segment was separated from the polymer. The molecular weight of the constituent unit contained in the oxyalkylene group-containing segment and the number of moles of oxyalkylene groups added in the constituent unit can be measured by analyzing the solution by gas chromatography mass spectrometry. The hydrophilic group concentration can be calculated by the following calculation formula.

The concentration (mmol/g) of the hydrophilic group in the polymer (A) is the number of moles of oxyalkylene groups added in the constituent unit/the molecular weight of the constituent unit

The polymer (A) has a solubility parameter (hereinafter, abbreviated as SP (solubility parameter)) of 12 (cal/cm)³)^1/2The above. Preferably 12 (cal/cm)³)^1/2～20(cal/cm³)^1/2More preferably 12 (cal/cm)³)^1/2～17(cal/cm³)^1/2. If the SP value of the polymer (A) is less than 12 (cal/cm)³)^1/2The affinity with the oxide film is low, and thus there is a problem that the withstand voltage is lowered.

The SP value of the polymer (A) can be adjusted by appropriately adjusting the SP value and the mole fraction of the constituent monomers. In order to increase the SP value of the polymer (A), a monomer having a highly polar functional group may be used as a constituent monomer.

The SP value of the polymer (A) is a value calculated by the method described in Fidors (polymers engineering and Science), February, 1974, Vol.14, No. 2P.147-154.

The SP value of the polymer (a) is obtained by calculating the SP value of each of the monomers constituting the polymer (a) by the above-mentioned method and averaging the SP values of the monomers based on the mole fraction of the monomer units constituting the polymer (a).

The hydrophilic group-containing polymer (a) is preferably a polymer in which an ethylenically unsaturated monomer (a) having a hydrophilic group is a monomer.

The hydrophilic group-containing ethylenically unsaturated monomer (a) is an ethylenically unsaturated monomer having at least one group selected from the group consisting of a hydroxyl group, an acidic group, a basic group and an oxyalkylene group having 2 to 3 carbon atoms.

Examples of the ethylenically unsaturated monomer (a) having a hydrophilic group include: a (meth) acrylic monomer having a hydrophilic group, a vinyl monomer having a hydrophilic group, a styrene monomer having a hydrophilic group, and the like.

In the present application, the expression "(meth) acrylic acid" means acrylic acid and/or methacrylic acid, the expression "(meth) acryloyl group" means acryloyl group and/or methacryloyl group, and the expression "(meth) acryloyloxy group" means acryloyloxy group and/or methacryloyloxy group.

Examples of the ethylenically unsaturated monomer (a) having a hydroxyl group as a hydrophilic group include: a (meth) acrylic monomer having a hydroxyl group, a vinyl monomer having a hydroxyl group, a styrene monomer having a hydroxyl group, and the like.

Examples of the (meth) acrylic monomer having a hydroxyl group as a hydrophilic group include: a hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms, a lactone adduct to the hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms, and an alkylene oxide adduct to the hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms.

Examples of the hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms include: monohydroxyalkyl (meth) acrylates having 4 to 12 carbon atoms [ e.g., 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate ], dihydroxyalkyl (meth) acrylates having 4 to 12 carbon atoms, and trihydroxyalkyl (meth) acrylates having 4 to 12 carbon atoms.

Examples of the monohydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms include: 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxy-1-methylethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-1-methylpropyl (meth) acrylate, 2-hydroxy-2-methylpropyl (meth) acrylate, 3-hydroxy-1-methylpropyl (meth) acrylate, 3-hydroxy-2-methylpropyl (meth) acrylate, 1, 4-cyclohexanedimethanol mono (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 2-hydroxy-1-methylethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxy-2-methylpropyl (meth) acrylate, 2-hydroxy-1-methylpropyl (meth, 7-hydroxyheptyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, and the like.

Examples of the dihydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms include glycerol mono (meth) acrylate and the like.

Examples of the trihydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms include pentaerythritol monoacrylate and the like.

The lactone added to the hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms is preferably a lactone having 2 to 12 carbon atoms, and examples thereof include: and caprolactone, propiolactone, butyrolactone, valerolactone, caprolactone, dodecalactone, and the like.

The number of moles of the lactone added is preferably 1 to 15 moles, and more preferably 1 to 5 moles. The lactone to be added may be used singly or in combination of two or more.

The 1 to 15 mol adduct of the lactone to the hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms includes: and 5-mole caprolactone adducts of 2- (meth) acryloyloxyethyl 6-hydroxycaproate, 2- (meth) acryloyloxyethyl 5-hydroxydodecanoate, and 2-hydroxyethyl (meth) acrylate.

The alkylene oxide added to the hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms is preferably an alkylene oxide having 2 to 10 carbon atoms, and examples thereof include: ethylene oxide, 1, 2-propylene oxide or 1, 3-propylene oxide, 1, 2-butylene oxide, 1, 3-butylene oxide, 1, 4-butylene oxide or 2, 3-butylene oxide, 3-methyltetrahydrofuran, 1, 2-decylene oxide, styrene oxide, epihalohydrin (epichlorohydrin and the like), and the like.

The number of moles of alkylene oxide added is preferably 1 to 40 moles. One kind of the alkylene oxide to be added may be used alone, or two or more kinds may be used in combination.

The alkylene oxide adduct to a hydroxyalkyl (meth) acrylate having 4 to 12 carbon atoms includes: 2- (2-hydroxyethoxy) ethyl (meth) acrylate, 2- (2- (2-hydroxyethoxy) ethoxy) ethyl (meth) acrylate, 2- (10-hydroxydecyloxy) ethyl (meth) acrylate, and a 30-mole ethylene oxide adduct to 2-hydroxyethyl (meth) acrylate.

Examples of the vinyl monomer having a hydroxyl group as a hydrophilic group include: vinyl alcohol, allyl alcohol, 4-vinyloxybutanol, 3-allyloxy-1, 2-propanediol, and the like.

Examples of the styrene monomer having a hydroxyl group as a hydrophilic group include cinnamyl alcohol, 4-hydroxybenzylideneacetone and the like.

Examples of the ethylenically unsaturated monomer (a) having an acidic group as a hydrophilic group include: a (meth) acrylic monomer having an acidic group, a vinyl monomer having an acidic group, a styrene monomer having an acidic group, and the like.

Examples of the (meth) acrylic monomer having an acidic group as the hydrophilic group include:

(meth) acrylic acid monomer having carboxyl group [ acid anhydride (preferably acid anhydride having 4 to 10 carbon atoms) adduct of (meth) acrylic acid monomer having hydroxyl group [2- (meth) acryloyloxyethyl succinate, 2- (meth) acryloyloxyethyl maleate, 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxyethyl hexahydrophthalate, etc. ], lactone (preferably lactone having 2 to 12 carbon atoms) adduct of (meth) acrylic acid [2- ((meth) acryloyloxy) acetic acid, 3- ((meth) acryloyloxy) propionic acid, 4- ((meth) acryloyloxy) butyric acid, 5- ((meth) acryloyloxy) valeric acid, 2- (meth) acryloyloxyethyl ester, etc. ], lactone (preferably lactone having 2 to 12 carbon atoms) adduct of (meth) acrylic acid, 6- ((meth) acryloyloxy) hexanoic acid, a caprolactone 5 mol adduct to (meth) acrylic acid, and the like ], (meth) acrylic acid, and the like ];

a (meth) acrylic monomer having a sulfo group [ e.g., 2-sulfoethyl (meth) acrylate and 2- (meth) acrylamide-2-methylpropanesulfonic acid ]; and

and (meth) acrylic acid monomers having a phosphoric acid group [2- ((meth) acryloyloxy) ethyl phosphate, etc. ], and the like.

Examples of the vinyl monomer having an acidic group as a hydrophilic group include: 3-pentenoic acid, 3-hexenoic acid, vinylsulfonic acid, vinylphosphonic acid, and the like.

Examples of the styrene monomer having an acidic group as a hydrophilic group include 4-vinylbenzoic acid and 4-styrenesulfonic acid.

Examples of the ethylenically unsaturated monomer (a) having a basic group as a hydrophilic group include: a (meth) acrylic monomer having a basic group, a vinyl monomer having a basic group, a styrene monomer having a basic group, and the like.

Examples of the (meth) acrylic monomer having a basic group as the hydrophilic group include: and (c) C3-20 (meth) acrylamides [ (meth) acrylamide, N-dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N-dibenzyl (meth) acrylamide, etc. ], C4-12 aminoalkyl (meth) acrylates [ (dimethylaminoethyl (meth) acrylate ], and C4-12 quaternary ammonium salts of aminoalkyl (meth) acrylates [ (trimethylethylammonium (meth) acrylate ], etc.

Examples of the vinyl monomer having a basic group as the hydrophilic group include: allyl amine, N-dimethylallylamine, N-diethylallylamine, and the like.

Examples of the styrene monomer having a basic group as a hydrophilic group include 4-aminostyrene and the like.

Examples of the ethylenically unsaturated monomer (a) having an oxyalkylene group having 2 to 3 carbon atoms as a hydrophilic group include: a (meth) acrylic monomer having an oxyalkylene group having 2 to 3 carbon atoms, a vinyl monomer having an oxyalkylene group having 2 to 3 carbon atoms, a styrene monomer having an oxyalkylene group having 2 to 3 carbon atoms, and the like.

Examples of the (meth) acrylic monomer having an oxyalkylene group having 2 to 3 carbon atoms as a hydrophilic group include alkyl [ preferably alkyl having 1 to 8 carbon atoms (such as methyl, ethyl, propyl and octyl) ] ethers of alkylene oxide (alkylene oxide having 2 to 3 carbon atoms) adducts to a (meth) acrylate having a hydroxyl group.

As the alkyl ether of the alkylene oxide adduct to the (meth) acrylate having a hydroxyl group, there can be mentioned: methoxypolyethylene glycol acrylate, 2- (2-methoxyethoxy) ethyl (meth) acrylate, 2- (2-ethoxyethoxy) ethyl (meth) acrylate, and 2- (2-octyloxyethoxy) ethyl (meth) acrylate.

Examples of the vinyl monomer having oxyalkylene groups having 2 to 3 carbon atoms as a hydrophilic group include diethylene glycol monovinyl ether and the like.

And styrene monomers having oxyalkylene groups having 2 to 3 carbon atoms include: an oxyalkylene adduct of cinnamyl alcohol having 2 to 3 carbon atoms and an oxyalkylene adduct of 4-hydroxybenzylideneacetone having 2 to 3 carbon atoms.

Among these ethylenically unsaturated monomers (a) having a hydrophilic group, from the viewpoint of improving withstand voltage, a (meth) acrylic monomer having a hydrophilic group is preferable, and further preferable are adducts of hydroxyalkyl (meth) acrylates having 4 to 12 carbon atoms and succinic anhydride, maleic anhydride, phthalic anhydride and hexahydrophthalic anhydride to hydroxyalkyl (meth) acrylates having 4 to 12 carbon atoms, and particularly preferable are 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate and 2- (meth) acryloyloxyethyl succinate.

One kind of the ethylenically unsaturated monomer (a) having a hydrophilic group may be used alone, or two or more kinds may be used in combination.

The polymer (A) having a hydrophilic group may be a copolymer of the above-mentioned ethylenically unsaturated monomer (a) having a hydrophilic group and a monomer other than the ethylenically unsaturated monomer (a) having a hydrophilic group (e.g., an ethylenically unsaturated monomer having no hydrophilic group).

Among the monomers other than the hydrophilic group-containing ethylenically unsaturated monomer (a), preferable ones from the viewpoint of copolymerizability and solubility in a solvent include: alkyl (meth) acrylates having 4 to 20 carbon atoms (e.g., methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate); c8-20 styrene compounds (such as styrene and p-methylstyrene); allyl compounds having 3 to 20 carbon atoms (such as allyl methyl ether and allyl butyl ether) and vinyl acetate, and more preferably alkyl (meth) acrylates having 4 to 20 carbon atoms, and particularly preferably butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate.

These monomers other than the hydrophilic group-containing ethylenically unsaturated monomer (a) may be used singly or in combination of two or more.

From the viewpoint of withstand voltage, the glass transition point (hereinafter, abbreviated as Tg) of the polymer (A) having a hydrophilic group in the present invention is preferably-100 to 80 ℃, more preferably-100 to 40 ℃, even more preferably-100 to 20 ℃, particularly preferably-100 to 5 ℃, and most preferably-100 to 0 ℃.

Tg of the present invention can be measured by a method according to "ASTM D3418-82" using a differential scanning calorimeter ("DSC 20" and "SSC/580" manufactured by Seiko Instruments (Ltd.), etc.).

The following mechanism is assumed for the mechanism of increasing the withstand voltage by setting Tg within the above range.

The polymer (a) having a hydrophilic group with Tg within the above range has high flexibility and easily permeates into a defect portion existing in the dielectric body, so that the repairability is improved, and as a result, the leak current is reduced and the withstand voltage is increased.

The number average molecular weight (hereinafter abbreviated as Mn) of the polymer (a) having a hydrophilic group is preferably 1,000 to 500,000, more preferably 2,000 to 200,000, particularly preferably 3,000 to 50,000, and most preferably 3,000 to 30,000, from the viewpoint of withstand voltage.

Mn of the polymer (a) having a hydrophilic group in the present invention is measured by gel Permeation chromatography (hereinafter, abbreviated as gpc (gel Permeation chromatography)) under the following conditions.

Apparatus (example): HLC-8120 made by Tosoh

Column (example): TSK GEL GMH 62 Roots (made by Tosoh)

Measuring temperature: 40 deg.C

Sample solution: 0.25 wt.% Tetrahydrofuran (THF) solution

Solution injection amount: 100 μ l

The detection device comprises: refractive index detector

Reference substance: standard POLYSTYRENE (TSK standard POLYSTYRENE)12 points (weight average molecular weight: 500, 1050, 2800, 5970, 9100, 18100, 37900, 96400, 190000, 355000, 1090000, 2890000) manufactured by Tosoh corporation

From the viewpoint of improving the withstand voltage, the weight ratio of the hydrophilic group-containing ethylenically unsaturated monomer (a) constituting the hydrophilic group-containing polymer (a) is preferably 50 to 100% by weight, and more preferably 60 to 100% by weight, based on the weight of all monomers constituting the hydrophilic group-containing polymer (a).

From the viewpoint of improving the withstand voltage, the weight ratio of the monomers other than the essential constituent monomers constituting the hydrophilic group-containing polymer (a) is preferably 50% by weight or less, and more preferably 40% by weight or less, based on the weight of all the monomers constituting the hydrophilic group-containing polymer (a).

The polymer (a) having a hydrophilic group can be produced by polymerizing the above-mentioned ethylenically unsaturated monomer (a) having a hydrophilic group and, if necessary, a monomer other than the ethylenically unsaturated monomer (a) having a hydrophilic group by a known method.

For example, the polymer (A) having a hydrophilic group can be produced by polymerizing a hydrophilic ethylenically unsaturated monomer (a) such as a (meth) acrylic monomer having a hydrophilic group by a known method (e.g., a method described in Japanese patent laid-open No. 5-117330).

In addition, a polymerization initiator may be used at the time of polymerization. Examples of the polymerization initiator include azobisisobutyronitrile and the like.

The polymer (a) in which the vinyl alcohol is a constituent monomer can be produced by partially saponifying polyvinyl acetate by a known method.

The partially saponified product of polyvinyl acetate can be produced by a known method, and can also be obtained from the market as Katsubishi (Gohsenx) LL (manufactured by the chemical industry of Japan).

The additive for electrolytic capacitors of the present invention may contain components other than the polymer (a) having a hydrophilic group, and examples of the components other than the polymer (a) include antioxidants, thermal deterioration inhibitors, and the like.

As the antioxidant, there may be mentioned: phosphorus antioxidants, hindered phenol antioxidants, thioether antioxidants, and the like.

As the phosphorus antioxidant, there can be mentioned: 2, 2-methylenebis (4, 6-di-t-butylphenyl) octyl phosphite (product name: Addiskota (ADK STAB) HP-10, manufactured by Asahi Denka Co., Ltd.), tris (2, 4-di-t-butylphenyl) phosphite (product name: Yiftix 168(IRUGAFOS168), manufactured by Ciba specialty Chemicals Co., Ltd.), and the like.

As the hindered phenol antioxidant, there can be mentioned: pentaerythritol-tetrakis [ 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] (manufactured by Ciba specialty Chemicals; trade name: Irganox 1010), octadecyl-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate (manufactured by Ciba specialty Chemicals; trade name: Irganox 1076), and the like.

Examples of the thermal deterioration inhibitor include 2-tert-butyl-6- (3' -tert-butyl-5 ' -methyl-hydroxybenzyl) -4-methylphenyl acrylate (manufactured by Sumitomo chemical Co., Ltd.; trade name: Sumilzer GM), and 2, 4-di-tert-amyl-6- (3',5' -di-tert-amyl-2 ' -hydroxy- α -methylbenzyl) phenyl acrylate (manufactured by Sumitomo chemical Co., Ltd.; trade name: Sumilzer GS).

In the additive for electrolytic capacitors of the present invention, the weight ratio of the polymer (a) having a hydrophilic group to the total weight of the additive for electrolytic capacitors is preferably 80 to 100% by weight, more preferably 90 to 100% by weight, and particularly preferably 96 to 100% by weight, from the viewpoint of improvement in withstand voltage.

When the additive for electrolytic capacitors of the present invention contains the antioxidant, the weight ratio of the antioxidant to the total weight of the additive for electrolytic capacitors is preferably 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, and particularly preferably 0.5 to 2% by weight.

When the additive for electrolytic capacitors of the present invention contains the thermal degradation inhibitor, the weight ratio of the thermal degradation inhibitor to the total weight of the additive for electrolytic capacitors is preferably 0.01 to 10 wt%, more preferably 0.1 to 5 wt%, and particularly preferably 0.5 to 2 wt%.

The conductive polymer dispersion liquid of the present invention is a conductive polymer dispersion liquid containing an additive for electrolytic capacitors. The conductive polymer dispersion preferably contains a solvent (B) and a conductive polymer (C) in addition to the additive for electrolytic capacitors.

Examples of the solvent (B) include water and an organic solvent.

As the organic solvent, there may be mentioned: alcohol solvents, amide solvents, ether solvents, ketone solvents, ester solvents, nitrile solvents, sulfoxide solvents, sulfone solvents, and the like. These organic solvents may be used alone or in combination of two or more.

As the alcohol solvent, there may be mentioned: methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol, monobutyl ether, polyethylene glycol (Mn: 600 or less), and the like.

Examples of the amide solvent include N-methylformamide and N, N-dimethylformamide.

As the ether solvent, there can be mentioned: diethyl ether, dimethyl ether, tetrahydrofuran, and the like.

Examples of the ketone solvent include 2-butanone and acetone.

Examples of the ester solvent include ethyl acetate, α -acetyl- γ -butyrolactone, β -butyrolactone, γ -valerolactone and δ -valerolactone.

As the nitrile solvent, there can be mentioned: acetonitrile, propionitrile, butyronitrile, acrylonitrile, methacrylonitrile, benzonitrile, and the like.

As the sulfoxide solvent, there can be mentioned: dimethyl sulfoxide, methyl ethyl sulfoxide, and diethyl sulfoxide.

Examples of the sulfone solvent include sulfolane and ethylmethylsulfone.

Among these solvents (B), water, alcohol solvents, sulfoxide solvents and sulfone solvents are preferable from the viewpoint of solubility of the polymer (a), and water, ethylene glycol, diethylene glycol and dimethyl sulfoxide are more preferable.

One kind of the solvent (B) may be used alone, or two or more kinds may be used in combination.

The conductive polymer (C) is a polymer exhibiting conductivity by an organic polymer having a pi-conjugated system in its main chain. The conductive resin composition is not particularly limited as long as it exhibits conductivity and has the effects of the present invention, and examples thereof include: polypyrrole conductive polymers, polythiophene conductive polymers, polyacetylene conductive polymers, polyphenylene conductive polymers, polyphenylacetylene conductive polymers, polyaniline conductive polymers, polyacene conductive polymers, polythiophene vinylene conductive polymers, and copolymers thereof.

Examples of the polythiophene conductive polymer include: polythiophene, poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), poly (3-butylthiophene), 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-carboxyethylthiophene), poly (3-methyl-4-carboxybutylthiophene), and the like.

Examples of the polypyrrole conductive polymer include: polypyrrole, poly (N-methylpyrrole), poly (3-ethylpyrrole), poly (3-N-propylpyrrole), poly (3-butylpyrrole), poly (3-octylpyrrole), poly (3-decylpyrrole), poly (3-dodecylpyrrole), poly (3, 4-dimethylpyrrole), poly (3, 4-dibutylpyrrole), poly (3-carboxypyrrole), poly (3-methyl-4-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), and the like.

As polyaniline conductive polymers, there can be mentioned: polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), poly (2-anilinesulfonic acid), poly (3-anilinesulfonic acid), and the like.

Among these conductive polymers, polypyrrole conductive polymers, polythiophene conductive polymers, and polyaniline conductive polymers are preferable from the viewpoint of stability in air and heat resistance, polythiophene conductive polymers are more preferable, and poly (3, 4-ethylenedioxythiophene) is particularly preferable from the viewpoint of conductivity.

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

The conductive polymer may be used together with a dopant in order to improve conductivity.

Examples of the dopant include p-toluenesulfonic acid and polystyrenesulfonic acid.

The conductive polymer dispersion is a conductive polymer dispersion containing an additive for electrolytic capacitors. The additive (D) may be contained in addition to the additive for electrolytic capacitors, the solvent (B) and the conductive polymer (C).

Examples of the additive (D) include polyethers and surfactants. From the viewpoint of conductivity, polyether is preferable, and from the viewpoint of film formability, a surfactant is preferable.

Examples of the polyether include polyethylene glycol [ trade name "PEG-400", manufactured by sanyo chemical industries (stock), Mn ═ 400], polyethylene glycol [ trade name "PEG-600", manufactured by sanyo chemical industries (stock), Mn ═ 600], and the like.

As the surfactant, there may be mentioned: nonionic surfactants, anionic surfactants, cationic surfactants, and the like. Among these surfactants, nonionic surfactants are preferable from the viewpoint of storage stability.

In the conductive polymer dispersion liquid of the present invention, the weight ratio of the additive for electrolytic capacitors to the weight of the conductive polymer dispersion liquid is preferably 0.1 to 30% by weight, more preferably 0.5 to 25% by weight, and particularly preferably 1 to 20% by weight, from the viewpoint of impregnation properties of the capacitor element.

In the electrolyte solution of the present invention, the weight ratio of the solvent (B) to the weight of the conductive polymer dispersion liquid is preferably 50 to 99% by weight, more preferably 60 to 99% by weight, and particularly preferably 70 to 99% by weight, from the viewpoint of dispersibility of the conductive polymer.

In the conductive polymer dispersion liquid of the present invention, the weight ratio of the conductive polymer (C) to the weight of the conductive polymer dispersion liquid is preferably 0.5 to 10% by weight, and more preferably 0.8 to 5% by weight, from the viewpoint of dispersibility of the conductive polymer.

In the electrolytic solution of the present invention, the weight ratio of the additive (G) to the weight of the conductive polymer dispersion liquid is preferably 0.01 to 5% by weight, and more preferably 0.05 to 2% by weight, from the viewpoint of solubility in the conductive polymer dispersion liquid.

The conductive polymer dispersion of the present invention can be produced by, for example, uniformly mixing the polymer (a), the dispersion obtained by dispersing the conductive polymer (C) in the solvent (B), and the optional additive (D) at a temperature of 20 to 80 ℃ by a known mechanical mixing method (for example, a method using a mechanical stirrer or a magnetic stirrer).

The electrolyte of the present invention is an electrolyte containing an additive for electrolytic capacitors. The electrolyte solution contains the solvent (B) in addition to the additive for electrolytic capacitors. The electrolyte (F) and other additives (G) may be added as necessary.

Among the solvents (B) used as the electrolytic solution, water, alcohol solvents, ester solvents, sulfoxide solvents, and sulfone solvents are preferable from the viewpoint of solubility of the polymer (a), and water, ethylene glycol, γ -butyrolactone, and sulfolane are more preferable.

One kind of the solvent (B) may be used alone, or two or more kinds may be used in combination.

The electrolyte (F) contained in the electrolyte solution of the present invention contains a cationic component (F1) and an anionic component (F2), and examples of the cationic component (F1) include: ammonia, triethylamine, dimethylethylamine, diethylmethylamine, dimethylamine, diethylamine, 1-methylimidazole, 1,2,3, 4-tetramethylimidazolinium, 1-ethyl-3-methylimidazolinium and the like, and among them, ammonia, dimethylethylamine, diethylamine, triethylamine and more preferably dimethylethylamine are preferable.

On the other hand, as the anion component (F2), there can be mentioned: adipic acid, azelaic acid, 1, 6-decanedicarboxylic acid, phthalic acid, maleic acid, benzoic acid, phosphoric acid and esters thereof, boric acid and esters thereof, and the like, and among them, phthalic acid is preferable.

One kind of the electrolyte (F) may be used alone, or two or more kinds may be used in combination.

In addition, the molar ratio of (F1) to (F2) is preferably 0.3 to 1.0, and more preferably 0.5 to 1.0, from the viewpoint of not dedoping the dopant taken into the solid electrolyte (conductive polymer described later).

Examples of other additives (G) include: nitro compounds (e.g., o-nitrobenzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, o-nitrophenol, and p-nitrophenol), boric acid, and polyvinyl alcohol (POVAL).

In the electrolytic solution of the present invention, the weight ratio of the polymer (a) to the weight of the electrolytic solution is preferably 5 to 70 wt%, more preferably 10 to 60 wt%, and particularly preferably 20 to 50 wt%, from the viewpoint of impregnation properties into the capacitor element.

In the electrolytic solution of the present invention, the weight ratio of the solvent (B) to the weight of the electrolytic solution is preferably 30 to 95% by weight, more preferably 40 to 90% by weight, and particularly preferably 40 to 80% by weight, from the viewpoint of suppressing drying (dry up) of the capacitor element.

In the electrolytic solution of the present invention, the weight ratio of the electrolyte (F) to the weight of the electrolytic solution is preferably 0 to 20% by weight, and more preferably 5 to 15% by weight, from the viewpoint of the chemical conversion property of the dielectric layer.

In the electrolyte solution of the present invention, the weight ratio of the additive (G) to the weight of the electrolyte solution is preferably 0 to 5 wt%, and more preferably 0.1 to 2 wt%, from the viewpoint of solubility in the electrolyte solution.

The electrolyte solution of the present invention can be produced by uniformly mixing the polymer (a), the solvent (B), and, if necessary, the electrolyte (F) and other additives (G) at a temperature of 20 to 80 ℃ by a known mechanical mixing method (for example, a method using a mechanical stirrer or a magnetic stirrer).

The electrolytic capacitor of the present invention is an electrolytic capacitor including a solid electrolyte layer, and is an electrolytic capacitor containing an additive for electrolytic capacitors. The electrolytic capacitor of the present invention includes a capacitor in which a cathode foil is disposed through a separator (e.g., manila hemp or kraft paper) in opposition to an anode foil including a dielectric layer and a solid electrolyte layer. And is a capacitor as follows: in the hybrid electrolytic capacitor, the layer of the solid electrolyte contains an electrolytic solution for electrolytic capacitors.

As the anode foil, a conductive material may be used.

As the conductive material, there can be mentioned: aluminum, titanium, tantalum, niobium, alloys thereof, and the like.

The anode foil preferably has a large surface area by a method such as making it porous by etching.

The dielectric layer is formed by anodizing the surface of the anode foil by chemical conversion treatment or the like, and thus an oxide of a conductive material used for the anode foil can be exemplified.

For example, when aluminum is used as the anode foil, the dielectric layer formed on the surface of the anode foil is aluminum oxide produced by chemical conversion.

The solid electrolyte layer formed on the surface of the dielectric layer is a layer containing a conductive polymer, a dopant, the polymer (A) having a hydrophilic group, and optionally an additive (D).

Examples of the conductive polymer include: polythiophene, poly (3, 4-ethylenedioxythiophene) (PEDOT), polypyrrole, and the like.

Further, as the dopant, p-toluenesulfonic acid, polystyrenesulfonic acid (PSS), and the like are exemplified.

Examples of the additive (D) include polyethers and surfactants.

Examples of the polyether include polyethylene glycol [ trade name "PEG-400", manufactured by sanyo chemical industries (stock), Mn ═ 400], polyethylene glycol [ trade name "PEG-600", manufactured by sanyo chemical industries (stock), Mn ═ 600], and the like.

As the surfactant, there may be mentioned: nonionic surfactants, anionic surfactants, cationic surfactants, and the like. Among these surfactants, nonionic surfactants are preferable from the viewpoint of storage stability.

From the viewpoint of withstand voltage, the weight ratio of the polymer (a) having a hydrophilic group contained in the solid electrolyte layer is preferably 20 to 80 wt%, more preferably 30 to 60 wt%, and particularly preferably 40 to 50 wt%, based on the weight of the solid electrolyte layer.

The solid electrolyte layer in the present invention can be formed by the following methods [ I ] and [ II ].

[I]

The solid electrolyte layer was formed by the method described in the following (1).

(1)

The solid electrolyte layer can be formed by a method in which the anode foil having the dielectric layer is impregnated with the conductive polymer dispersion [ a solution containing the hydrophilic group-containing polymer (a), the conductive polymer (C), the dopant, and the solvent (B) (water, etc.) ], and then dried.

[I] In the solid electrolyte layer forming method of (1), the operation of (1) may be performed a plurality of times to form a multilayer solid electrolyte layer.

If the operation (1) is performed at least once, the following operations (2) and/or (3) may be performed instead of the operation (1).

In the case where the operation (1), (2), and/or (3) is performed a plurality of times, in each operation (1), (2), or (3), the anode foil having the dielectric layer and the solid electrolyte layer obtained by performing the operation (1), (2), or (3) may be used instead of the anode foil having the dielectric layer.

(2)

The solid electrolyte layer can be formed by a method in which the anode foil having the dielectric layer is impregnated into the conductive polymer dispersion [ a solution containing the conductive polymer (C), the dopant, and the solvent (B) (water, etc.) ], and then dried.

The conductive polymer dispersion may contain boric acid and a boric acid ester as necessary.

(3)

The solid electrolyte layer can be formed by polymerizing a monomer constituting the conductive polymer by a method of alternately impregnating the anode foil having the dielectric layer with a solid electrolyte composition [ a solution (aqueous solution or the like) of a monomer constituting the conductive polymer (C) (thiophene, ethylenedioxythiophene, pyrrole, or the like) and a dopant ], and a solution (aqueous solution or the like) of an oxidant (iron oxide, or the like) ].

[II]

The operation (2) or (3) is performed at least once to form a solid electrolyte layer (not containing the polymer (A) having a hydrophilic group) on the surface of the dielectric layer of the anode foil.

Then, the solid electrolyte layer containing the polymer (a) having a hydrophilic group can be formed by a method of impregnating the anode foil having the dielectric layer and the solid electrolyte layer in a solution (aqueous solution or the like) of the polymer (a) having a hydrophilic group and then drying the impregnated anode foil.

In the solid electrolyte layer forming method of [ II ], the operation (1) may be performed instead of the operations (2) and (3).

Examples of the cathode foil include a laminate of carbon paste and silver paste, and an aluminum foil.

The electrolytic capacitor of the present invention can be manufactured by the following method, for example.

First, the aluminum etched foil as the anode foil was subjected to chemical conversion treatment by the above-described method, and a dielectric layer was formed on the surface of the aluminum etched foil, thereby producing an anode including the anode foil and the dielectric layer.

Then, electrode tabs were connected to the anode foil and the cathode foil, and the anode foil and the cathode foil were opposed to each other via a separator to produce an element. Then, in order to repair the cut surface or the defective portion, the element was repaired at a voltage of 250V in an ammonium borate aqueous solution to produce a capacitor element.

Next, in the method of [ I ] or [ II ], the capacitor element is immersed in the conductive polymer dispersion, the solid electrolyte composition, a solution of an oxidizing agent, and the like, whereby the solid electrolyte layer is formed on the surface of the dielectric layer in the anode foil having the dielectric layer in the capacitor element.

The electrolytic capacitor was produced by the above method.

As the solid electrolyte, there may be mentioned: and electrically conductive polymers such as polythiophene, poly 3, 4-ethylenedioxythiophene, and polypyrrole.

The conductive polymer has a dopant incorporated therein, and the dopant plays a role of exhibiting conductivity.

Examples of the dopant include p-toluenesulfonic acid and polystyrenesulfonic acid.

Examples of the cathode foil include a laminate of carbon paste and silver paste, and an aluminum foil.

Specific configurations of the electrolytic capacitor of the present invention include the following configurations.

Has a capacitor element, a pair of leads, and an outer package. A pair of leads are connected to the capacitor elements, respectively. The outer cover leads out the other end of the lead to the outside and seals the capacitor element.

The outer package includes a cylindrical case in which a capacitor element containing an electrolyte solution by a method described later is housed, and a sealing member which is formed by passing lead wires through-holes through which the lead wires are inserted, and is sealed by compressing the lead wires at a necking portion provided on an outer peripheral surface of the case.

A capacitor element of the present invention comprises an anode foil having a dielectric layer on a surface thereof, and a layer of a solid electrolyte in contact with the dielectric layer of the anode foil.

The anode foil is formed by roughening an aluminum foil by etching treatment and further subjecting the surface of the aluminum foil to chemical conversion treatment to form an anodic oxide film as a dielectric layer.

Next, an anode foil having a dielectric layer, a cathode foil, and a separator were laminated and wound to form a capacitor element (a layer having no solid electrolyte).

Further, a layer of solid electrolyte is formed between the anode foil and the cathode foil in the capacitor element (layer without solid electrolyte), whereby the capacitor element in the present invention can be obtained.

Examples of the method for producing the layer of the solid electrolyte include the following (1) and (2).

(1)

The layer of the solid electrolyte can be formed on the surface of the dielectric layer in the capacitor element by a method of impregnating the capacitor element (layer without the solid electrolyte) with the dispersion solution of the solid electrolyte [ a solution in which the solid electrolyte is dispersed in a solvent (water or the like) ] and then drying the same.

(2)

The solid electrolyte layer can be formed on the surface of the dielectric layer in the capacitor element by polymerizing the monomer constituting the solid electrolyte by a method of alternately impregnating the capacitor element (layer without the solid electrolyte) with a solid electrolyte composition [ a mixture of the monomer constituting the solid electrolyte (thiophene, ethylenedioxythiophene, pyrrole, etc.), a dopant and a solvent (water, etc.) ], and a solution (aqueous solution, etc.) of an oxidizing agent (iron oxide, etc.).

The electrolytic capacitor of the present invention can be produced by immersing the capacitor element formed as described above in the electrolytic solution for electrolytic capacitors of the present invention and vacuum-impregnating the capacitor element with the electrolytic solution, whereby the electrolytic solution for electrolytic capacitors of the present invention enters gaps between layers of the solid electrolyte included in the capacitor element.