JPWO2019027019A1 - Additives for electrolytic capacitors, conductive polymer dispersions, electrolytic solutions and electrolytic capacitors - Google Patents

Abstract

The present invention is an additive for an electrolytic capacitor used in an electrolytic capacitor having a solid electrolyte layer, which contains a polymer (A) having a hydrophilic group, wherein the concentration of the hydrophilic group of the polymer (A) is high. An additive for an electrolytic capacitor, which has a solubility parameter of 18 mmol/g or less based on the weight of the polymer (A) and a solubility parameter of the polymer (A) of 12 (cal/cm3)1/2 or more.

Description

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

In recent years, with the miniaturization of electronic products, a small size and large capacity high frequency capacitor has been required. As such a capacitor, an electrolytic capacitor having a small equivalent series resistance (hereinafter abbreviated as ESR) and excellent frequency characteristics is under development. The electrolytic capacitor includes an anode foil made of aluminum and tantalum or the like, a dielectric layer such as aluminum oxide or tantalum oxide formed on the anode foil, and a cathode foil. Above all, 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 lower ESR than an electrolytic capacitor using an electrolytic solution.
However, since the solid electrolytic capacitor does not contain a substance such as an electrolytic solution that plays a role in repairing the dielectric, the solid electrolytic capacitor has a large leakage current and a low withstand voltage, so that the guaranteed voltage cannot be increased. ..

In order to solve this problem, Patent Document 1 discloses a technique for suppressing the leakage current by covering the surface of the dielectric with polyvinyl alcohol. Patent Document 2 discloses a technique in which a withstand voltage can be improved by introducing a copolymer such as acrylic acid and vinylphenol into a solid electrolyte layer. However, with these techniques, neither the reduction of the leakage current nor the effect of improving the withstand voltage was sufficient.

Further, in AV equipment and automobile electrical equipment, there is an increasing demand for higher reliability. Therefore, in the solid electrolytic capacitor as well, in addition to performance such as low ESR, it is necessary to improve low leakage current and short-circuit resistance.
To meet these demands, a so-called hybrid type, in which, in addition to a solid electrolyte such as a conductive polymer such as polypyrrole, polyaniline, and polythiophene, as an electrolyte material, an electrolytic solution excellent in repairing a defect portion of an anodized film that is a dielectric is used together Electrolytic capacitors have been proposed (for example, Patent Documents 3 and 4).

In these hybrid electrolytic capacitors, the electrolytic solution enters the gap between the solid electrolytes of the conductive polymer, and the degree of contact between the dielectric oxide film and the electrolyte is improved. Therefore, the electrostatic capacity 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 leakage current is small, and the short circuit can be suppressed.
However, in the conventional hybrid electrolytic capacitor, the suppression of the leakage current, especially in the high temperature environment, was not sufficient.

JP 2001-102255 A International Publication No. 2015/133121 JP, 11-186110, A JP, 2014-195116, A

An object of the present invention is to reduce the leakage current of an electrolytic capacitor provided with a solid electrolyte layer and improve the withstand voltage.

The present inventors have arrived at the present invention as a result of studies to achieve the above object.
That is, the present invention is an additive for an electrolytic capacitor used in an electrolytic capacitor having a solid electrolyte layer, which contains a polymer (A) having a hydrophilic group, and the concentration of the hydrophilic group of the polymer (A). Is 18 mmol/g or less based on the weight of the polymer (A), and the solubility parameter of the polymer (A) is 12 (cal/cm ³ ) ^1/2 or more. Further, the present invention is 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. ..

According to the present invention, it is possible to provide an additive for an electrolytic capacitor which has a small leakage current and an excellent withstand voltage.

The additive for an electrolytic capacitor of the present invention is an additive for an electrolytic capacitor used in an electrolytic capacitor having a solid electrolyte layer, which contains a polymer (A) having a hydrophilic group and is hydrophilic to the polymer (A). An additive for an electrolytic capacitor, wherein the concentration of the functional group is 18 mmol/g or less based on the weight of the polymer (A), and the solubility parameter of the polymer (A) is 12 (cal/cm ³ ) ^1/2 or more. is there.

First, the polymer (A) having the hydrophilic group will be described.
The hydrophilic group is not particularly limited, but may be, for example, a hydroxyl group, an acidic group, a basic group or an oxyalkylene group having 2 to 3 carbon atoms. Examples of the acidic group include a carboxyl group, a sulfonic acid group, a phosphonic acid group 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 oxyethylene group and 1,2- or 1,3-oxypropylene group.
Among these hydrophilic groups, a hydroxyl group and an acidic group are preferable from the viewpoint of leakage current, and a hydroxyl group is more preferable.

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, more preferably 10 mmol/g, and the lower limit is preferably 2 mmol/g, further preferably 4 mmol/g. When the concentration of the hydrophilic group of the polymer (A) exceeds 18 mmol/g, the intermolecular force becomes strong and the polymer is deposited 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 of the polymer (A) can be adjusted by selecting the constituent monomers and the weight ratio.
The concentration of the hydrophilic group of the polymer (A) is defined by the amount (mol number) of the substance of the hydrophilic group contained in 1 g of the polymer (A). The concentration of the hydrophilic group of the polymer (A) was measured by the following method.

When the hydrophilic group is a hydroxyl group, the concentration of the hydrophilic group of the polymer (A) is a value calculated by the following calculation formula by obtaining the hydroxyl value by the method described in JIS K 0700:1992.
Concentration of hydrophilic group of polymer (A) (mmol/g)
= Hydroxyl value (mgKOH/g)/56.1

When the hydrophilic group is an acidic group, the concentration of the hydrophilic group of the polymer (A) is a value calculated from the acid value obtained by the method described in JIS K 0700:1992 and the following formula.
Concentration of hydrophilic group of polymer (A) (mmol/g)
= Acid value (mgKOH/g)/56.1

When the hydrophilic group is a base, the concentration of the hydrophilic group of the polymer (A) is a value calculated by the following calculation formula by obtaining the base value by the method described in JIS K 2501:2003.
Concentration of hydrophilic group of polymer (A) (mmol/g)=base number/56.1

When the hydrophilic group is an oxyalkylene group having 2 to 3 carbon atoms, the concentration of the hydrophilic group of the polymer (A) can be determined by the following method.
The polymer (A) is hydrolyzed in a 1 mol/l sodium hydroxide aqueous solution at 100° C. for 2 hours to obtain a solution in which a segment containing an oxyalkylene group is separated from the polymer. By analyzing this solution by gas chromatography-mass spectrometry, the molecular weight of the constituent unit contained in the segment containing the oxyalkylene group and the number of moles of the oxyalkylene group added in the constituent unit can be measured. The hydrophilic group concentration can be calculated by the following calculation formula.
Concentration of hydrophilic group of polymer (A) (mmol/g)
= Number of moles of oxyalkylene group added in constitutional unit/molecular weight of constitutional unit

The solubility parameter (hereinafter abbreviated as SP value) of the polymer (A) is 12 (cal/cm ³ ) ^1/2 or more. It is preferably 12 to 20 (cal/cm ³ ) ^1/2 , and more preferably 12 to 17 (cal/cm ³ ) ^1/2 . If the SP value of the polymer (A) is less than 12 (cal/cm ³ ) ^1/2 , the polymer (A) has a low affinity with the oxide film, and thus 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 the Fedors method (Polymer Engineering and Science, February, 1974, Vol. 14, No. 2 P. 147 to 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 method, and averaging the SP values of the respective monomers based on the mole fraction of the constituent monomer units. It is the value.

The polymer (A) having a hydrophilic group is preferably a polymer having an ethylenically unsaturated monomer (a) having a hydrophilic group as a constituent monomer.
The ethylenically unsaturated monomer having a hydrophilic group (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. Are listed.

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, and a styrene monomer having a hydrophilic group.
In the present application, the notation “(meth)acrylic” means acryl and/or methacryl, the notation “(meth)acryloyl” means acryloyl and/or methacryloyl, and the notation “(meth)acryloyloxy”. Means acryloyloxy and/or methacryloyloxy.

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, and a styrene monomer having a hydroxyl group.

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 Examples thereof include alkylene oxide adducts of the above-mentioned hydroxyalkyl (meth)acrylate having 4 to 12 carbon atoms.

Examples of the hydroxyalkyl (meth)acrylate having 4 to 12 carbon atoms include monohydroxyalkyl (meth)acrylate having 2 to 12 carbon atoms [2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate and 2 -Hydroxybutyl (meth)acrylate and the like], dihydroxyalkyl (meth)acrylate having 4 to 12 carbon atoms and trihydroxyalkyl (meth)acrylate 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, and 2-hydroxy-1-methyl. Ethyl (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- Examples thereof include hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth)acrylate and 8-hydroxyoctyl (meth)acrylate.
Examples of the dihydroxyalkyl (meth)acrylate having 4 to 12 carbon atoms include glycerin mono(meth)acrylate.
Examples of the trihydroxyalkyl (meth)acrylate having 4 to 12 carbon atoms include pentaerythritol monoacrylate.

The lactone to be 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 acetolactone, propiolactone, butyrolactone, valerolactone, caprolactone and laurolactone. To be
The number of moles of the lactone added is preferably 1 to 15 moles, more preferably 1 to 5 moles. The lactone to be added may be used alone or in combination of two or more.
Examples of the addition product of 1 to 15 mol of lactone to the hydroxyalkyl (meth)acrylate having 4 to 12 carbon atoms include 2-(meth)acryloyloxyethyl 6-hydroxyhexanoate and 2-(meth)hydroxydodecanoic acid. ) Acryloyloxyethyl and 2-hydroxyethyl (meth)acrylate to which 5 mol of caprolactone is added.

As the alkylene oxide added to the hydroxyalkyl (meth)acrylate having 4 to 12 carbon atoms, an alkylene oxide having 2 to 10 carbon atoms is preferable, and ethylene oxide, 1,2- or 1,3-propylene oxide, 1,2 -, 1,3-, 1,4- or 2,3-butylene oxide, 3-methyltetrahydrofuran, 1,2-decene oxide, styrene oxide, epihalohydrin (epichlorohydrin, etc.) and the like can be mentioned.
The number of moles of the alkylene oxide added is preferably 1 to 40 moles. The alkylene oxides to be added may be used alone or in combination of two or more.
Examples of the alkylene oxide adduct of hydroxyalkyl (meth)acrylate having 4 to 12 carbon atoms include 2-(2-hydroxyethoxy)ethyl (meth)acrylate and 2-(2-(2-hydroxy)(meth)acrylate. Examples include ethoxy)ethoxy)ethyl, 2-(10-hydroxydetoxy)ethyl (meth)acrylate, and 30 mol of 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, 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 and 4-hydroxybenzalacetone.

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

As the (meth)acrylic monomer having an acidic group as a hydrophilic group,
(Meth)acrylic monomer having a carboxy group [an acid anhydride (an acid anhydride having 4 to 10 carbon atoms is preferable) addition product to the (meth)acrylic monomer having a hydroxyl group] [succinic acid 2-(meth)acryloyloxy] Ethyl, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, etc.], lactone to (meth)acrylic acid (Preferred lactone having 2 to 12 carbon atoms) Adduct (preferably 1 to 5 mol adduct) [2-((meth)acryloyloxy)ethanoic acid, 3-((meth)acryloyloxy)propanoic acid, 4- ((Meth)acryloyloxy)butanoic acid, 5-((meth)acryloyloxy)pentanoic acid, 6-((meth)acryloyloxy)hexanoic acid, and a caprolactone 5 mol adduct to (meth)acrylic acid] and (meth)acrylic Acid, etc.];
A (meth)acrylic monomer having a sulfo group [2-sulfoethyl (meth)acrylate and 2-(meth)acrylamido-2-methylpropanesulfonic acid, etc.]; and a (meth)acrylic monomer having a phospho group [phosphoric acid 2- ((Meth)acryloyloxy)ethyl and the like] and the like.

Examples of vinyl monomers 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 (meth)acrylic monomers having a basic group, vinyl monomers having a basic group, styrene monomers having a basic group, and the like. ..

Examples of the (meth)acrylic monomer having a basic group as a hydrophilic group include (meth)acrylamide having a carbon number of 3 to 20 [(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-isopropyl(meth)acrylamide. , Dimethylaminopropyl(meth)acrylamide, N-(2-hydroxyethyl)(meth)acrylamide and N,N-dibenzyl(meth)acrylamide, etc.], C4-12 aminoalkyl(meth)acrylate [(meth)] Dimethylaminoethyl acrylate] and a quaternary ammonium salt of an aminoalkyl (meth)acrylate having 4 to 12 carbon atoms [(meth)acrylic acid trimethylethylammonium salt] and the like.

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

4-aminostyrene etc. are mentioned as a styrene monomer which has a basic group as a hydrophilic group.

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 and an oxy group having 2 to 3 carbon atoms. Examples thereof include vinyl monomers having an alkylene group and styrene monomers having an oxyalkylene group having 2 to 3 carbon atoms.

The (meth)acrylic monomer having an oxyalkylene group having 2 to 3 carbon atoms as a hydrophilic group is an adduct of alkylene oxide (wherein the alkylene oxide has 2 to 3 carbon atoms) to a (meth)acrylate having a hydroxyl group. Alkyl [preferably alkyl having 1 to 8 carbon atoms (methyl, ethyl, propyl, octyl and the like)] ether and the like can be mentioned.
Examples of the alkyl ether of an alkylene oxide adduct of (meth)acrylate having a hydroxyl group include methoxy polyethylene glycol acrylate, 2-(2-methoxyethoxy)ethyl (meth)acrylate, and 2-(2-ethoxy)(meth)acrylate. Examples thereof include ethoxy)ethyl and 2-(2-octoxyethoxy)ethyl (meth)acrylate.

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

Examples of the styrene monomer having an oxyalkylene group 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-hydroxybenzalacetone having 2 to 3 carbon atoms. Are listed.

Among these ethylenically unsaturated monomers (a) having a hydrophilic group, a (meth)acrylic monomer having a hydrophilic group is preferable from the viewpoint of improving the withstand voltage, and more preferable is one having 4 to 4 carbon atoms. Succinic anhydride, maleic anhydride, phthalic anhydride and hexahydrophthalic anhydride adducts of 12 hydroxyalkyl (meth)acrylates and hydroxyalkyl (meth)acrylates having 4 to 12 carbon atoms, particularly preferably 2 -Hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl acrylate and 2-(meth)acryloyloxyethyl succinate.
The ethylenically unsaturated monomer (a) having a hydrophilic group may be used alone or in combination of two or more.

The polymer (A) having the hydrophilic group includes the ethylenically unsaturated monomer (a) having the hydrophilic group and a monomer (hydrophilic group) other than the ethylenically unsaturated monomer (a) having the hydrophilic group. It may be a copolymer with an ethylenically unsaturated monomer having no group).
Among the monomers other than the ethylenically unsaturated monomer (a) having a hydrophilic group, as a preferable one from the viewpoint of copolymerizability and solubility in a solvent, an alkyl (meth)acrylate having 4 to 20 carbon atoms [ Methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate and lauryl (meth)acrylate, etc.]; Styrene compounds having 8 to 20 carbon atoms (styrene and Paramethylstyrene, etc.); C3-C20 allyl compounds (allylmethyl ether, allylbutyl ether, etc.), vinyl acetate, and the like, and more preferred are C4-C20 alkyl (meth)acrylates. Particularly preferred are butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate.
Monomers other than these ethylenically unsaturated monomers (a) having a hydrophilic group may be used alone or in combination of two or more.

The glass transition point (hereinafter abbreviated as Tg) of the polymer (A) having a hydrophilic group in the invention is preferably −100 to 80° C., more preferably −100 to 40 from the viewpoint of withstand voltage. C., more preferably −100 to 20° C., particularly preferably −100 to 5° C., and most preferably −100 to 0° C.
The Tg of the present invention can be measured by a method based on “ASTM D3418-82” using a differential scanning calorimeter [“DSC20” and “SSC/580” manufactured by Seiko Instruments Inc.]. ..

It is assumed that the mechanism for improving the withstand voltage by setting Tg within the above range is as follows.
The polymer (A) having a hydrophilic group having a Tg within the above range has relatively high flexibility and easily penetrates into the defective portion existing in the dielectric, so that the repairability is enhanced and, as a result, the leakage current is increased. Becomes smaller and the withstand voltage becomes higher.

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

The Mn of the polymer (A) having a hydrophilic group in the invention is measured by gel permeation chromatography (hereinafter abbreviated as GPC) under the following conditions.
Device (example): HLC-8120 manufactured by Tosoh Corporation
Column (one example): TSK GEL GMH6 2 [manufactured by Tosoh Corporation]
Measurement temperature: 40℃
Sample solution: 0.25 wt% THF solution Injection volume: 100 μl
Detector: Refractive index detector Reference substance: Tohso Corp. standard polystyrene (TSK standard POLYSTYRENE) 12 points (weight average molecular weight: 500 1050 2800 5970 9100 18100 37900 96400 190000 355000 1090000 2890000)

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 the above-mentioned hydrophilic group-containing polymer (A). It is preferably 50 to 100% by weight, and more preferably 60 to 100% by weight, based on the weight of all the monomers constituting (1).
From the viewpoint of improving the withstand voltage, the weight ratios of the monomers other than the above-mentioned essential constituent monomers constituting the polymer (A) having the hydrophilic group are all components constituting the polymer (A) having the hydrophilic group. It is preferably 50% by weight or less, and more preferably 40% by weight or less, based on the weight of the monomer.

The polymer (A) having a hydrophilic group is a monomer other than the ethylenically unsaturated monomer (a) having a hydrophilic group, and optionally an ethylenically unsaturated monomer (a) having a hydrophilic group. Can be produced by polymerizing by a known method.
For example, as the polymer (A) having a hydrophilic group, an ethylenically unsaturated monomer (a) having a hydrophilic group such as a (meth)acrylic monomer having a hydrophilic group can be used by a known method (Japanese Patent Laid-Open No. 5-117330). It can be produced by polymerizing according to the method described in Japanese Patent Publication No.
A polymerization initiator can be used during the polymerization. Examples of the polymerization initiator include azobisisobutyronitrile and the like.
The polymer (A) containing vinyl alcohol as 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, or can be obtained from the market as GOHSENX LL [manufactured by Nippon Synthetic Chemical Industry Co., Ltd.].

The additive for an electrolytic capacitor of the present invention may contain a component other than the polymer (A) having a hydrophilic group, and examples of the component other than the polymer (A) include an antioxidant and a heat deterioration inhibitor. Are listed.

Examples of the antioxidant include phosphoric acid antioxidants, hindered phenol antioxidants, thioether antioxidants and the like.
As the phosphorylation inhibitor, 2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphite (manufactured by Asahi Denka Co., Ltd.; trade name: ADEKA STAB HP-10), tris(2,4-di-t-). Butylphenyl)phosphite (manufactured by Ciba Specialty Chemicals; trade name: IRUGAFOS168).
As the hindered phenol antioxidant, pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (Ciba Specialty Chemicals; trade name IRGANOX1010), octadecyl -3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (manufactured by Ciba Specialty Chemicals; trade name IRGANOX1076) and the like can be mentioned.

As the thermal deterioration inhibitor, 2-t-butyl-6-(3'-t-butyl-5'-methyl-hydroxybenzyl)-4-methylphenyl acrylate (Sumitomo Chemical Co.; trade name Sumilizer GM), 2 , 4-di-t-amyl-6-(3′,5′-di-t-amyl-2′-hydroxy-α-methylbenzyl)phenyl acrylate (Sumitomo Chemical Co., Ltd.; trade name Sumilizer GS) and the like. To be

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 from the viewpoint of improving withstand voltage. %, more preferably 90 to 100% by weight, particularly preferably 96 to 100% by weight.
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 deterioration inhibitor, the weight ratio of the thermal deterioration inhibitor to the total weight of the additive for electrolytic capacitors is 0.01 to 10% by weight. Is more preferable, 0.1 to 5% by weight is more preferable, and 0.5 to 2% by weight is particularly preferable.

The conductive polymer dispersion of the present invention is a conductive polymer dispersion containing an additive for electrolytic capacitors. The conductive polymer dispersion liquid 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 organic solvents.
Examples of the organic solvent include 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.
Examples of the alcohol solvent include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, ethylene glycol, monobutyl ether and polyethylene glycol (Mn: 600 or less).
Examples of the amide solvent include N-methylformamide and N,N-dimethylformamide.
Examples of the ether solvent include 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-butyrolactone, γ-valerolactone and δ-valerolactone.
Examples of the nitrile solvent include acetonitrile, propionitrile, butyronitrile, acrylonitrile, methacrylonitrile, and benzonitrile.
Examples of the sulfoxide solvent include dimethyl sulfoxide, methyl ethyl sulfoxide, diethyl sulfoxide and the like.
Examples of the sulfone solvent include sulfolane and ethylmethyl sulfone.
Among these solvents (B), water, alcohol solvent, sulfoxide solvent and sulfone solvent are preferable from the viewpoint of solubility of the polymer (A), and more preferable are water, ethylene glycol, diethylene glycol and dimethyl sulfoxide. Is.
As the solvent (B), one type may be used alone, or two or more types may be used in combination.

The conductive polymer (C) is an organic polymer whose main chain is a π-conjugated system and which has conductivity. It is not particularly limited as long as it exhibits conductivity and the effect of the present invention, and examples thereof include polypyrrole conductive polymer, polythiophene conductive polymer, polyacetylene conductive polymer, polyphenylene conductive polymer, polyphenylene vinylene conductive polymer, polyaniline. Examples thereof include 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(3,3 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-butylene dioxythiophene), poly(3-methyl-4-methoxythiophene), poly(3-methyl -4-ethoxythiophene), poly(3-carboxythiophene), poly(3-methyl-4-carboxythiophene), poly(3-methyl-4-carboxyethylthiophene), poly(3-methyl-4-carboxybutyl) Thiophene) and the like.

Examples of the polypyrrole conductive polymer include polypyrrole, poly(N-methylpyrrole), poly(3-methylpyrrole), poly(3-ethylpyrrole), poly(3-n-propylpyrrole), poly(3-butylpyrrole). ), poly(3-octylpyrrole), poly(3-decylpyrrole), poly(3-dodecylpyrrole), poly(3,4-dimethylpyrrole), poly(3,4-dibutylpyrrole), poly(3- Carboxypyrrole), poly(3-methyl-4-carboxypyrrole), poly(3-methyl-4-carboxyethylpyrrole), poly(3-methyl-4-carboxybutylpyrrole), poly(3-hydroxypyrrole), Examples thereof include poly(3-methoxypyrrole), poly(3-ethoxypyrrole), poly(3-butoxypyrrole), poly(3-hexyloxypyrrole), and poly(3-methyl-4-hexyloxypyrrole).

Examples of the polyaniline conductive polymer include polyaniline, poly(2-methylaniline), poly(3-isobutylaniline), poly(2-anilinesulfonic acid), poly(3-anilinesulfonic acid), and the like.

Among these conductive polymers, from the viewpoint of stability and heat resistance in air, polypyrrole conductive polymer, polythiophene conductive polymer and polyaniline conductive polymer are preferable, and polythiophene conductive polymer is more preferable. It is a high molecular weight polymer, and particularly preferably poly(3,4-ethylenedioxythiophene) from the viewpoint of conductivity.
The conductive polymers may be used alone or in combination of two or more.

The conductive polymer may be used together with a dopant to improve conductivity.
Examples of the dopant include p-toluenesulfonic acid and polystyrenesulfonic acid.

The conductive polymer dispersion liquid is a conductive polymer dispersion liquid containing an additive for electrolytic capacitors. In addition to the additive for electrolytic capacitor, the solvent (B) and the conductive polymer (C), the additive (D) may be contained.
Examples of the additive (D) include polyethers and surfactants. From the viewpoint of electrical conductivity, polyether is preferable, and from the viewpoint of film-forming property, surfactant is preferable.

As the polyether, polyethylene glycol [trade name "PEG-400", manufactured by Sanyo Chemical Industry Co., Ltd., Mn=400], polyethylene glycol [trade name "PEG-600", manufactured by Sanyo Chemical Industry Co., Ltd., Mn= 600] and the like.

Examples of the surfactant include nonionic surfactants, anionic surfactants and cationic surfactants. Among these surfactants, nonionic surfactants are preferable from the viewpoint of storage stability.

In the conductive polymer dispersion of the present invention, the weight ratio of the additive for an electrolytic capacitor to the weight of the conductive polymer dispersion is 0.1 to 30% by weight from the viewpoint of impregnation into a capacitor element. It is more preferably 0.5 to 25% by weight, and particularly preferably 1 to 20% by weight.
In the electrolytic solution of the present invention, the weight ratio of the solvent (B) to the weight of the conductive polymer dispersion is preferably 50 to 99% by weight from the viewpoint of dispersibility of the conductive polymer, and more preferably 60. ˜99% by weight, particularly preferably 70 to 99% by weight.
In the conductive polymer dispersion of the present invention, the weight ratio of the conductive polymer (C) to the weight of the conductive polymer dispersion is 0.5 to 10% by weight from the viewpoint of dispersibility of the conductive polymer. It is preferably present, and more preferably 0.8 to 5% by weight.
In the electrolytic solution of the present invention, the weight ratio of the additive (G) to the weight of the conductive polymer dispersion is 0.01 to 5% by weight from the viewpoint of solubility in the conductive polymer dispersion. Is preferable, and more preferably 0.05 to 2% by weight.

The conductive polymer dispersion liquid of the present invention comprises, for example, a dispersion liquid in which a polymer (A) and a conductive polymer (C) are dispersed in a solvent (B) and, if necessary, an additive (D). It can be produced by uniformly mixing in the temperature range of -80°C by using a known mechanical mixing method (for example, a method using a mechanical stirrer or a magnetic stirrer).

The electrolytic solution of the present invention is an electrolytic solution containing an additive for electrolytic capacitors. The electrolytic solution contains the above solvent (B) in addition to the additive for electrolytic capacitors. If necessary, the electrolyte (F) and other additives (G) can be added.
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 more preferable are water and ethylene glycol. , Γ-butyrolactone and sulfolane.
As the solvent (B), one type may be used alone, or two or more types may be used in combination.

The electrolyte (F) contained in the electrolytic solution of the present invention is composed of a cation component (F1) and an anion component (F2), and examples of the cation component (F1) include ammonia, triethylamine, dimethylethylamine, diethylmethylamine and dimethyl. Amine, diethylamine, 1-methylimidazole, 1,2,3,4-tetramethylimidazolinium, 1-ethyl-3-methylimidazolinium and the like can be mentioned, among which ammonia, dimethylethylamine, diethylamine, triethylamine are preferable, More preferred is dimethylethylamine.
On the other hand, examples of the anion component (F2) include adipic acid, azelaic acid, 1,6-decanedicarboxylic acid, phthalic acid, maleic acid, benzoic acid, phosphoric acid and its esterified product, and boric acid and its esterified product. Of these, phthalic acid is preferred.
As the electrolyte (F), one type may be used alone, or two or more types may be used in combination.

Further, the molar ratio of (F1) and (F2) is preferably (F1)/(F2), from the viewpoint of not dedoping the dopant incorporated in the solid electrolyte (conductive polymer described later). It is 3 to 1.0, and more preferably 0.5 to 1.0.

Other additives (G) include nitro compounds (o-nitrobenzoic acid, p-nitrobenzoic acid, m-nitrobenzoic acid, o-nitrophenol and p-nitrophenol, etc.), boric acid, poval and the like. To be

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% by weight, and more preferably 10 to 60% by weight, from the viewpoint of impregnation property into a capacitor element. And particularly preferably 20 to 50% by weight.
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, from the viewpoint of suppressing dry-up of the capacitor element. And particularly preferably 40 to 80% by weight.
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 chemical conversion of the dielectric layer. is there.
In the electrolytic solution of the present invention, the weight ratio of the additive (G) to the weight of the electrolytic solution is preferably 0 to 5% by weight from the viewpoint of solubility in the electrolytic solution, and more preferably 0.1 to 5. It is 2% by weight.

The electrolytic solution of the present invention comprises, for example, a polymer (A), a solvent (B), and optionally an electrolyte (F) and other additives (G) in a known machine in a temperature range of 20 to 80°C. It can be manufactured by uniform mixing by using a dynamic 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, which is an electrolytic capacitor containing an additive for electrolytic capacitors. Examples of the electrolytic capacitor of the present invention include a capacitor configured by arranging a cathode foil facing a positive electrode foil including a dielectric layer and a solid electrolyte layer with a separator (such as Manila hemp and kraft paper) interposed therebetween. .. Alternatively, in the hybrid electrolytic capacitor, the solid electrolyte layer is a capacitor containing an electrolytic solution for an electrolytic capacitor.

A conductive material can be used as the anode foil.
Examples of the conductive material include aluminum, titanium, tantalum, niobium, and alloys thereof.
The anode foil preferably has a large surface area by a method such as making it porous by etching.

Since the dielectric layer is formed by anodizing the surface of the anode foil by chemical conversion treatment or the like, an oxide of a conductive substance used for the anode foil can be used.
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 the hydrophilic group, and optionally an additive (D).
Examples of the conductive polymer include polythiophene, poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole and the like.
In addition, examples of the dopant include p-toluenesulfonic acid and polystyrenesulfonic acid (PSS).
Examples of the additive (D) include polyethers and surfactants.
As the polyether, polyethylene glycol [trade name "PEG-400", manufactured by Sanyo Chemical Industry Co., Ltd., Mn=400], polyethylene glycol [trade name "PEG-600", manufactured by Sanyo Chemical Industry Co., Ltd., Mn= 600] and the like.
Examples of the surfactant include nonionic surfactants, anionic surfactants and cationic surfactants. Among these surfactants, nonionic surfactants are preferable from the viewpoint of storage stability.

From the viewpoint of withstand voltage, the weight ratio of the hydrophilic group-containing polymer (A) contained in the solid electrolyte layer is preferably 20 to 80% by weight based on the weight of the solid electrolyte layer, and more preferably The amount is 30 to 60% by weight, and particularly preferably 40 to 50% by weight.

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

[I]
The solid electrolyte layer is formed by the method described in (1) below.
(1)
The anode foil having a dielectric layer was replaced with the above conductive polymer dispersion [the above-mentioned hydrophilic group-containing polymer (A), conductive polymer (C), dopant and solvent (B) (water, etc.)]. It is possible to form a solid electrolyte layer by a method of impregnating the solution containing] and then drying.

In the method for forming a solid electrolyte layer according to [I], the operation (1) above may be carried out a plurality of times to form a plurality of solid electrolyte layers.
If the operation (1) is performed at least once, the operation (2) and/or (3) below may be performed instead of the operation (1).
When performing the operations (1), (2) and/or (3) multiple times, in each operation (1), (2) or (3), the anode foil having the dielectric layer is replaced. Then, the anode foil having the dielectric layer and the solid electrolyte layer obtained by performing the operation (1), (2) or (3) immediately before may be used.
(2)
By a method of impregnating the anode foil having a dielectric layer with the above-mentioned conductive polymer dispersion [solution containing conductive polymer (C), dopant and solvent (B) (water etc.) and then drying. The solid electrolyte layer can be formed.
In addition, the conductive polymer dispersion liquid may contain boric acid and boric acid ester, if necessary.
(3)
An anode foil having a dielectric layer is prepared by using a solid electrolyte composition [a solution of a monomer (thiophene, ethylenedioxythiophene, pyrrole, etc.) constituting the conductive polymer (C) and a dopant (aqueous solution, etc.)], and an oxidizer ( The solid electrolyte layer can be formed by polymerizing the monomer constituting the conductive polymer by a method of alternately impregnating with a solution (aqueous solution or the like) of iron oxide or the like).

[II]
The operation of either (2) or (3) above 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. ..
Thereafter, the anode foil having the dielectric layer and the solid electrolyte layer is impregnated with the solution (aqueous solution or the like) of the polymer (A) having the hydrophilic group, and then dried to obtain a polymer having a hydrophilic group. A solid electrolyte layer containing (A) can be formed.
In addition, in the solid electrolyte layer forming method according to [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, aluminum foil, and the like.

The electrolytic capacitor of the present invention can be manufactured, for example, by the following method.
First, an aluminum etched foil as an anode foil is subjected to chemical conversion treatment by the above method to form a dielectric layer on the surface of the aluminum etched foil, and an anode composed of the anode foil and the dielectric layer is produced.
After that, an electrode tab is connected to the anode foil and the cathode foil, and they are made to face each other with a separator interposed therebetween to produce an element. Then, in order to repair the cut surface and the defective portion, the element is subjected to repair chemical formation at a voltage of 250 V in an aqueous solution of ammonium borate to manufacture a capacitor element.
Next, in the above method [I] or [II], the capacitor element is dipped into the conductive polymer dispersion liquid, the solid electrolyte composition and the oxidizer solution, etc. Regarding the anode foil having the dielectric layer, the solid electrolyte layer is formed on the surface of the dielectric layer.
An electrolytic capacitor is manufactured by the above method.

Examples of the solid electrolyte include conductive polymers such as polythiophene and poly3,4-ethylenedioxythiophene, and polypyrrole.
A dopant is incorporated in this conductive polymer, and the dopant plays a role of expressing 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, aluminum foil, and the like.

Specific configurations of the electrolytic capacitor of the present invention include the following configurations.
It has a capacitor element, a pair of lead wires, and an exterior body. Each of the pair of lead wires is connected to the capacitor element. The exterior body encloses the capacitor element so that the lead wire is led out to the outside.
The outer body is composed of a cylindrical case and a sealing body. The case accommodates a capacitor element containing an electrolytic solution by a method described below, and the sealing body has a penetrating body through which lead wires are respectively inserted. It is sealed by being passed through the hole and compressed by a drawn portion provided on the outer peripheral surface of the case.

The capacitor element of the present invention has an anode foil having a dielectric layer on its surface and a solid electrolyte layer in contact with the dielectric layer of this anode foil.
The anode foil is formed by roughening an aluminum foil by etching treatment and further subjecting the surface thereof to a chemical conversion treatment of an anodized film which is a dielectric layer.
Next, a capacitor element (without a solid electrolyte layer) is formed by stacking and winding an anode foil having a dielectric layer, a cathode foil, and a separator.

Then, by forming a layer of the solid electrolyte between the anode foil and the cathode foil in the capacitor element (without the solid electrolyte layer), the capacitor element of the present invention can be obtained.
The following methods (1) and (2) may be mentioned as the method for producing the solid electrolyte layer.
(1)
The dielectric layer in the capacitor element is formed by impregnating the capacitor element (without solid electrolyte layer) with the dispersion solution of the solid electrolyte [solution in which the solid electrolyte is dispersed in a solvent (water etc.)] and then drying. A layer of solid electrolyte can be formed on the surface.
(2)
A capacitor element (without a solid electrolyte layer) was prepared by adding a solid electrolyte composition [a mixture of a monomer (thiophene, ethylenedioxythiophene, pyrrole, etc.), a dopant and a solvent (water, etc.) constituting the solid electrolyte], and an oxidizing agent (oxidation). The solid electrolyte layer can be formed on the surface of the dielectric layer in the capacitor element by polymerizing the monomer forming the solid electrolyte by a method of alternately impregnating with a solution of iron or the like (aqueous solution).

The capacitor element formed as described above is immersed in the electrolytic solution for electrolytic capacitor of the present invention, and the electrolytic solution is vacuum impregnated into the electrolytic solution to form a gap between the solid electrolyte layers of the capacitor element according to the present invention. The electrolytic solution for an electrolytic capacitor of (1) enters into the electrolytic capacitor of the present invention.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
In the following, parts represent parts by weight.
Moreover, Mn of the polymer (A) and the comparative polymer (RA) having the following hydrophilic groups was measured by GPC under the following conditions.
Device: Tosoh Corp. HLC-8120
Column: TSK GEL GMH6 2 [manufactured by Tosoh Corporation]
Measurement temperature: 40°C
Sample solution: 0.25 wt% THF solution Injection volume: 100 μl
Detector: Refractive index detector Reference substance: Tosoh Corporation standard polystyrene (TSK standard POLYSTYRENE) 12 points (weight average molecular weight: 500 1050 2800 5970 9100 18100 37900 96400 190000 355000 1090000 2890000)

Further, the Tg of each of the following polymers (A-1 to 24) having a hydrophilic group and the polymers (RA-1, 2) for comparison has a differential scanning calorimeter [DSC20 manufactured by Seiko Instruments Inc.]. ] And “SSC/580” and the like] are used to measure in accordance with “ASTM D3418-82”.

<Example 1: Preparation of additive (P-1) for electrolytic capacitor containing polymer (A-1) having hydrophilic group>
To a flask equipped with a stirrer, a thermometer and a cooling tube, 30 parts by weight of toluene [manufactured by Wako Pure Chemical Industries, Ltd.] and 9.5 parts by weight of acrylic acid [manufactured by Wako Pure Chemical Industries, Ltd.] (132 mmol ( Hereinafter, described as mmol)) and 2-hydroxyethyl acrylate [manufactured by Wako Pure Chemical Industries, Ltd.] 4.6 parts by weight (40 mmol) were added, and the mixture was heated to 80° C. under stirring. A solution of 0.9 parts by weight of azobisisobutyronitrile [manufactured by Wako Pure Chemical Industries, Ltd.] in 5 parts by weight of toluene was added dropwise thereto over 3 hours. After completion of the dropping, the mixture was heated with stirring for another 3 hours while maintaining 80°C. Then, toluene is distilled off by heating at 100° C. under a reduced pressure of 0.5 kPa to synthesize a high molecular weight polymer (A-1) having a hydrophilic group and containing the polymer (A-1). The additive (P-1) for electrolytic capacitors was produced. Mn of the polymer (A-1) was 5,600, and Tg was 56°C.

<Example 2: Preparation of additive (P-2) for electrolytic capacitor containing polymer (A-2) having hydrophilic group>
A polymer (A-2) having a hydrophilic group was prepared in the same manner as in Example 1 except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1. The contained electrolytic capacitor additive (P-2) was produced. Mn of the polymer (A-2) was 5,300, and Tg was 11°C.

<Example 3: Preparation of additive (P-3) for electrolytic capacitor containing polymer (A-3) having hydrophilic group>
A polymer (A-3) having a hydrophilic group was prepared in the same manner as in Example 1 except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1. The contained electrolytic capacitor additive (P-3) was produced. Mn of the polymer (A-3) was 5,500, and Tg was 4°C.

<Example 4: Preparation of additive (P-4) for electrolytic capacitor containing polymer (A-4) having hydrophilic group>
A polymer (A-4) having a hydrophilic group was prepared in the same manner as in Example 1 except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1. The contained electrolytic capacitor additive (P-4) was produced. Mn of the polymer (A-4) was 6,100, and Tg was -2°C.

<Example 5: Preparation of additive (P-5) for electrolytic capacitor containing polymer (A-5) having hydrophilic group>
A polymer (A-5) having a hydrophilic group was prepared in the same manner as in Example 1 except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1. The contained electrolytic capacitor additive (P-5) was prepared. Mn of the polymer (A-5) was 4,600, and Tg was -40°C.

<Example 6: Preparation of additive (P-6) for electrolytic capacitor containing polymer (A-6) having hydrophilic group>
To a flask equipped with a stirrer, a thermometer and a cooling tube, 30 parts by weight of toluene [manufactured by Wako Pure Chemical Industries, Ltd.] and 14.1 parts by weight (121 mmol) of 2-hydroxyethyl acrylate were added, and the mixture was stirred at 80 Heated to °C. A solution of 0.9 parts by weight of azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) in 5 parts of toluene was added dropwise thereto over 3 hours. After completion of the dropping, the mixture was heated with stirring for another 3 hours while maintaining 80°C. Then, the toluene was distilled off by heating at 100° C. under a reduced pressure of 0.5 kPa to prepare an additive (P-6) for an electrolytic capacitor containing the polymer (A-6) having a hydrophilic group. .. Mn of the polymer (A-7) was 6,100, and Tg was -15°C.

<Example 7: Preparation of additive for electrolytic capacitor (P-7) containing polymer (A-7) having hydrophilic group>
The procedure of Example 6 was repeated except that 0.9 parts by weight of azobisisobutyronitrile was changed to 1.8 parts by weight, and a polymer having a hydrophilic group (A-7) was obtained. The contained electrolytic capacitor additive (P-7) was prepared. Mn of the polymer (A-7) was 2,500 and Tg was -15°C.

<Example 8: Preparation of additive (P-8) for electrolytic capacitor containing polymer (A-8) having hydrophilic group>
A polymer having a hydrophilic group (A-8) was prepared in the same manner as in Example 6 except that 30 parts by weight of toluene was changed to 30 parts by weight of methyl ethyl ketone [manufactured by Wako Pure Chemical Industries, Ltd.]. An additive (P-8) for an electrolytic capacitor containing was prepared. The polymer (A-8) had an Mn of 3,100 and a Tg of -15°C.

<Example 9: Preparation of additive (P-9) for electrolytic capacitor containing polymer (A-9) having hydrophilic group>
Example 6 was repeated except that 0.9 parts by weight of azobisisobutyronitrile was changed to 0.4 parts by weight, and a polymer having a hydrophilic group (A-9) was prepared. The contained electrolytic capacitor additive (P-9) was prepared. The polymer (A-9) had Mn of 15,000 and Tg of -15°C.

<Example 10: Preparation of additive for electrolytic capacitor (P-10) containing polymer (A-10) having hydrophilic group>
Example 6 was repeated except that 0.9 parts by weight of azobisisobutyronitrile was changed to 0.2 parts by weight, and a polymer having a hydrophilic group (A-10) was prepared. The contained electrolytic capacitor additive (P-10) was produced. Mn of the polymer (A-10) was 36,000 and Tg was -15°C.

<Example 11: Preparation of additive (P-11) for electrolytic capacitor containing polymer (A-11) having hydrophilic group>
Example 6 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1 to obtain a polymer (A-11) having a hydrophilic group. The contained electrolytic capacitor additive (P-11) was produced. The polymer (A-11) had an Mn of 5,600 and a Tg of -7°C.

<Example 12: Preparation of additive for electrolytic capacitor (P-12) containing polymer (A-12) having hydrophilic group>
Example 6 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer described in Table 1 to obtain a polymer (A-12) having a hydrophilic group. The contained additive for electrolytic capacitors (P-12) was produced. The polymer (A-12) had an Mn of 6,200 and a Tg of -40°C.

<Example 13: Preparation of additive for electrolytic capacitor (P-13) containing polymer (A-13) having hydrophilic group>
To a flask equipped with a stirrer, a thermometer and a cooling tube, 30 parts of toluene [manufactured by Wako Pure Chemical Industries, Ltd.], 12.7 parts by weight of 4-hydroxybutyl acrylate (88.2 mmol) and 1.4 parts by weight of butyl acrylate. Parts (10.9 mmol) were charged and heated to 80° C. with stirring. A solution of 0.9 parts by weight of azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) in 5 parts by weight of toluene was added dropwise thereto over 3 hours. After completion of the dropping, the mixture was heated with stirring for another 3 hours while maintaining 80°C. Then, toluene is distilled off by heating at 100° C. under a reduced pressure of 0.5 kPa, and an additive for an electrolytic capacitor (P-13) containing a high molecular polymer (A-13) having a hydrophilic group is added. It was made. Mn of the high molecular polymer (A-13) was 5,800, and Tg was -42°C.

<Example 14: Preparation of additive for electrolytic capacitor (P-14) containing polymer (A-14) having hydrophilic group>
A polymer (A-14) having a hydrophilic group was prepared in the same manner as in Example 13, except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1. The contained electrolytic capacitor additive (P-14) was prepared. The Mn of the polymer (A-14) was 4,800, and the Tg was -40°C.

<Example 15: Preparation of additive for electrolytic capacitor (P-15) containing polymer (A-15) having hydrophilic group>
Example 13 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1 to obtain a polymer (A-15) having a hydrophilic group. The contained additive (P-15) for electrolytic capacitors was produced. The Mn of the polymer (A-15) was 6,300, and the Tg was 16°C.

<Example 16: Preparation of additive (P-16) for electrolytic capacitor containing polymer (A-16) having hydrophilic group>
A polymer (A-16) having a hydrophilic group was prepared in the same manner as in Example 6 except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1. The contained electrolytic capacitor additive (P-16) was produced. The Mn of the polymer (A-16) was 5,800, and the Tg was 165°C.

<Example 17: Preparation of additive (P-17) for electrolytic capacitor containing polymer (A-17) having hydrophilic group>
A polymer (A-17) having a hydrophilic group was prepared in the same manner as in Example 7, except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1. The contained electrolytic capacitor additive (P-17) was prepared. The Mn of the polymer (A-17) was 6,500, and the Tg was -50°C.

<Example 18: Preparation of additive (P-18) for electrolytic capacitor containing polymer (A-18) having hydrophilic group>
Example 13 was repeated in the same manner as in Example 13 except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1, and the polymer (A-18) having a hydrophilic group was contained. An electrolytic capacitor additive (P-18) was prepared. The polymer (A-18) had an Mn of 4,100 and a Tg of 65°C.

<Example 19: Preparation of additive for electrolytic capacitor (P-19) containing polymer (A-19) having hydrophilic group>
Example 6 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1, and the polymer (A-19) having a hydrophilic group was contained. An electrolytic capacitor additive (P-19) was prepared. The polymer (A-19) had an Mn of 7,500 and a Tg of 18°C.

<Example 20: Preparation of additive (P-20) for electrolytic capacitor containing polymer (A-20) having hydrophilic group>
The procedure of Example 6 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1, and the polymer (A-20) having a hydrophilic group was contained. An electrolytic capacitor additive (P-20) was prepared. The Mn of the polymer (A-20) was 3,600, and the Tg was 30°C.

<Example 21: Preparation of additive (P-21) for electrolytic capacitor containing polymer (A-21) having hydrophilic group>
The procedure of Example 6 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1 to contain the polymer (A-21) having a hydrophilic group. An electrolytic capacitor additive (P-21) was prepared. The Mn of the polymer (A-21) was 4,500, and the Tg was 55°C.

<Example 22: Preparation of additive for electrolytic capacitor (P-22) containing polymer (A-22) having hydrophilic group>
The procedure of Example 1 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1, and the polymer (A-22) having a hydrophilic group was contained. An electrolytic capacitor additive (P-22) was prepared. The Mn of the polymer (A-22) was 4,200, and the Tg was 10°C.

<Example 23: Preparation of additive for electrolytic capacitor (P-23) containing polymer (A-23) having hydrophilic group>
The procedure of Example 1 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1, and the polymer containing a hydrophilic group (A-23) was contained. An electrolytic capacitor additive (P-23) was prepared. The Mn of the polymer (A-23) was 6,000, and the Tg was 82°C.

<Example 24: Preparation of additive for electrolytic capacitor (P-24) containing polymer (A-24) having hydrophilic group>
The procedure of Example 1 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer shown in Table 1, and the polymer (A-24) having a hydrophilic group was contained. An electrolytic capacitor additive (P-24) was prepared. The polymer (A-24) had an Mn of 6,500 and a Tg of 75°C.

<Comparative Example 1: Preparation of electrolytic capacitor additive (RP-2) containing polymer (RA-1) having no hydrophilic group>
Example 6 was repeated except that the ethylenically unsaturated monomer having a hydrophilic group was changed to the monomer described in Table 1, and the electrolysis containing the comparative polymer (RA-1) was performed. An additive for capacitors (RP-2) was prepared. Mn of the polymer (RA-1) was 7,500 and Tg was -70°C.

As a comparative polymer (RA-2) having a hydrophilic group but having a high Tg, polyvinyl alcohol (JC-25, Tg: 80° C., manufactured by Japan Vinyl Acetate & Poval Co., Ltd.) was used.

Table 1 shows the structures, Mn and Tg of the above polymers (A-1) to (A-24) and comparative polymers (RA-1) to (RA-2). The unit of numerical values in the composition column is parts by weight, and parenthesized values are millimoles.
The monomers used are as follows.
Acrylic acid [Wako Pure Chemical Industries, Ltd.]
Methacrylic acid [Wako Pure Chemical Industries, Ltd.]
Mono (2-acryloyloxyethyl) succinate [manufactured by Tokyo Chemical Industry Co., Ltd.]
Mono (2-methacryloyloxyethyl) succinate [Product name "Light Ester HO-MS(N)", Kyoeisha Chemical Co., Ltd.]
2-hydroxyethyl acrylate [Wako Pure Chemical Industries, Ltd.]
2-Hydroxypropyl acrylate [Tokyo Chemical Industry Co., Ltd.]
4-hydroxybutyl acrylate [trade name "4-HBA", manufactured by Osaka Organic Chemical Industry Co., Ltd.]
1,4-Cyclohexanedimethanol monoacrylate (abbreviated as CHDMMA) [Product name "Funkryl FA-610A", manufactured by Hitachi Chemical Co., Ltd.]
Glycerin monoacrylate [Product name "Blenmer GLM", NOF Corporation]
2-hydroxyethyl methacrylate (abbreviated as HEMA) [Tokyo Chemical Industry Co., Ltd.]
N-(2-hydroxyethyl)acrylamide [manufactured by Tokyo Chemical Industry Co., Ltd.]
Acrylamide [Tokyo Chemical Industry Co., Ltd.]
2-Hydroxyethyl acrylate ethylene oxide 2 mol adduct (abbreviated as HEA 2EO) [trade name "Blenmer AE90", NOF Corporation]

<Examples 25 to 45 and Comparative Examples 3 to 6: Preparation of conductive polymer dispersions>
The conductive polymer dispersion liquids (Q-1) to (Q-21) and the comparative conductive polymer dispersion liquids (RQ-1) to (RQ-4) were mixed by the composition of the weight parts shown in Table 2. Was prepared.

The following compounds were used as the compounds shown in Table 2.
PEDOT/PSS aqueous dispersion (meaning the same below): An aqueous dispersion of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonic acid (PSS), manufactured by Heraeus, Clevios PH500, total weight of PEDOT and PSS based on the weight of PEDOT/PSS aqueous dispersion (PEDOT/PSS concentration): 1.4 wt%

<Examples 46 to 68 and Comparative Examples 7 to 10>
The electrolytic capacitors (S-1) to (S-23) of the present invention and the electrolytic capacitors (RS-1) to (RS-4) for comparison were produced by the method described below.

<Examples 46 to 66 and Comparative Examples 7 to 10: Preparation 1 of Solid Electrolytic Capacitor>
An electrode tab is connected to an anode foil (formed aluminum foil: made by JCC, 115HC9-323Vf) having a dielectric layer and a cathode foil (unformed aluminum foil: made by JCC, 80LJ11B), and kraft paper is used as a separator. To face each other to obtain an element. In order to repair the cut surface and the defective portion, the device was subjected to repair formation at a voltage of 250 V in an aqueous solution of ammonium borate to obtain a capacitor device.
Next, the PEDOT/PSS aqueous dispersion was impregnated with a capacitor element and dried at 150° C. for 30 minutes to form a solid electrolyte layer on the surface of the dielectric layer.
Subsequently, the conductive polymer dispersions of Examples 25 to 45 and Comparative Preparation Examples 3 to 7 shown in Table 2 were impregnated and dried at 150° C. for 30 minutes to further form a solid electrolyte layer.
Finally, the capacitor element was stored in a case and caulking was performed to obtain electrolytic capacitors of Examples 46 to 66 and Comparative Examples 7 to 10.

<Example 67: Preparation of solid electrolytic capacitor 2>
An electrode tab is connected to an anode foil (formed aluminum foil: made by JCC, 115HC9-323Vf) having a dielectric layer and a cathode foil (unformed aluminum foil: made by JCC, 80LJ11B), and kraft paper is used as a separator. To face each other to obtain an element. In order to repair the cut surface and the defective portion, the device was subjected to repair formation at a voltage of 250 V in an aqueous solution of ammonium borate to obtain a capacitor device.
Next, the conductive polymer dispersion liquid (Q-6) prepared in Example 30 was impregnated with a capacitor element and dried at 150° C. for 30 minutes to form a solid electrolyte layer on the surface of the dielectric layer.
Then, it was impregnated with a PEDOT/PSS aqueous dispersion and dried at 150° C. for 30 minutes to further form a solid electrolyte layer. Finally, the capacitor element was stored in a case and caulking was performed to obtain a solid electrolytic capacitor of Example 67.

<Example 68: Preparation 3 of solid electrolytic capacitor>
An electrode tab is connected to an anode foil (formed aluminum foil: JCCVf323) having a dielectric layer and a cathode foil (unformed aluminum foil: manufactured by JCC, 80LJ11B) to face each other via kraft paper as a separator to obtain a device. It was In order to repair the cut surface and the defective portion, the element was subjected to repair chemical formation at a voltage of 120 V in an aqueous solution of ammonium borate to obtain a capacitor element.
Next, a commercially available PEDOT/PSS aqueous dispersion was impregnated with the capacitor element and dried at 150° C. for 30 minutes to form a solid electrolyte layer on the surface of the dielectric layer.
Further, it was again impregnated with the PEDOT/PSS aqueous dispersion and dried at 150° C. for 30 minutes to further form a solid electrolyte layer.
Then, it was impregnated with an aqueous solution (solid content concentration: 30% by weight) of the polymer (A-6) having a hydrophilic group produced in Example 6 and dried at 150° C. for 30 minutes.
Finally, the capacitor element was stored in a case and caulking was performed to obtain a solid electrolytic capacitor of Example 68 in which the solid electrolyte layer contains the polymer 1 having a hydrophilic group.

The "equivalent series resistance (ESR)", "leakage current" and "withstand voltage" of the solid electrolytic capacitors obtained in Examples 46 to 68 and Comparative Examples 7 to 10 were evaluated by the following methods. The results are shown in Table 3.

<ESR>
The ESR value at 100 kHz of the solid electrolytic capacitor was measured using an LCR meter (LCR HiTester 3532-50 manufactured by Hioki Electric Co., Ltd.).
The lower the ESR value, the better the stability of the operation.
<Leakage current>
A voltage of 20 V was applied to the solid electrolytic capacitor, and the leakage current after 60 seconds was measured.
<Withstand voltage>
A voltage was applied to the solid electrolytic capacitor obtained by the above method in a constant current mode of 0.2 mA with a DC power supply device (GP0650-05R, manufactured by Takasago Seisakusho), the voltage was automatically boosted, and the voltage immediately before the voltage suddenly dropped due to discharge was applied. Withstand voltage.

The electrolytic capacitors of Examples 46 to 68 of the present invention showed good results in all items of ESR change rate, leakage current and withstand voltage.
On the other hand, in the comparative electrolytic capacitors of Comparative Examples 7 to 10, at least one of the items of ESR change rate, leakage current, and withstand voltage deteriorated.

<Examples 69 to 80 and Comparative Examples 11 to 12: Electrolyte solutions>
Polymer (A) and comparative polymer (A'-1), electrolyte (C) (dimethylethylamine and phthalic acid), solvent (B) (ethylene glycol) were mixed according to the compounding parts (parts by weight) of Table 4. Then, electrolytic solutions (R-1) to (R-12) and electrolytic solutions (RR-1) to (RR-2) for comparative examples were produced.

Next, using the above electrolytic solutions (R-1) to (R-12) and the electrolytic solutions (RR-1) to (RR-2) of Comparative Examples, electrolytic capacitors (S-24) to (S-). 35) and the electrolytic capacitors (RS-5) to (RS-6) of Comparative Example were produced by the following procedures.
An electrode tab is connected to an anode foil (formed aluminum foil: made by JCC, 115HC9-323Vf) having a dielectric layer and a cathode foil (unformed aluminum foil: made by JCC, 80LJ11B), and kraft paper is used as a separator. To face each other to obtain an element. In order to repair the cut surface and the defective portion, the device was subjected to repair formation at a voltage of 250 V in an aqueous solution of ammonium borate to obtain a capacitor device.
Next, a commercially available PEDOT/PSS aqueous dispersion was impregnated with the capacitor element and dried at 150° C. for 30 minutes. This operation was repeated 3 times to form a solid electrolyte layer on the surface of the dielectric layer.
Subsequently, the electrolytic solutions (R-1) to (R-12) shown in Table 4 and the electrolytic solutions (RR-1) to (RR-2) of Comparative Examples were respectively applied to the above capacitor elements at 50° C. Vacuum impregnation (vacuum degree: 20 mmHg) was performed for a minute.
Finally, the capacitor element was stored in a case and caulking was performed to obtain electrolytic capacitors (S-24) to (S-35) and electrolytic capacitors (RS-5) to (RS-6) of comparative examples.

The initial characteristics of the produced electrolytic capacitor and the characteristics after the test were measured and evaluated by the following methods. The results are shown in Table 4.

<Initial evaluation>
As initial evaluation, capacitance, ESR, leakage current, and withstand voltage were measured.
The capacitance was measured at 120 Hz and the ESR value was measured at 100 kHz, and the leakage current was measured after the rated voltage was applied for 1 minute.
<Capacitance>
The capacitance of the solid electrolytic capacitor at 120 Hz was measured using an LCR meter (LCR HiTester 3532-50 manufactured by Hioki Electric Co., Ltd.).
<ESR>
The ESR value at 100 kHz of the solid electrolytic capacitor was measured using an LCR meter (LCR HiTester 3532-50 manufactured by Hioki Electric Co., Ltd.).
<Leakage current>
A voltage of 20 V was applied to the solid electrolytic capacitor, and the leakage current after 60 seconds was measured.
<Withstand voltage>
A voltage was applied to the solid electrolytic capacitor obtained by the above method in a constant current mode of 0.2 mA with a DC power supply device (GP0650-05R, manufactured by Takasago Seisakusho), the voltage was automatically boosted, and the voltage immediately before the voltage suddenly dropped due to discharge was applied. Withstand voltage.

<Evaluation after accelerated test>
In order to carry out an acceleration test by accelerating the volatilization of the solvent (B), after leaving the capacitor element open in a constant temperature bath at 125° C. for 500 hours without storing it in a case, the same evaluation as in the initial evaluation was performed. An evaluation was made.
Further, the capacitance and ESR were calculated as the rate of change based on the value of the initial characteristic.

The electrolytic capacitors of Examples 69 to 80 of the present invention also had good initial characteristics and good results in the acceleration test.
On the other hand, the comparative electrolytic capacitors of Comparative Examples 11 and 12 were deteriorated in terms of the capacitance change rate, the ESR change rate, and the leakage current.

The solid electrolytic capacitor containing the additive for an electrolytic capacitor of the present invention has a low ESR, a small leakage current, and a high withstand voltage, and thus can be suitably used as a component for electric products and electronic products that require high performance.

Claims (10)

An additive for an electrolytic capacitor used in an electrolytic capacitor having a solid electrolyte layer, comprising a polymer (A) having a hydrophilic group, wherein the concentration of the hydrophilic group of the polymer (A) is the polymer (A). 18 mmol/g or less based on the weight of the polymer, and the solubility parameter of the polymer (A) is 12 (cal/cm ³ ) ^1/2 or more. The additive for electrolytic capacitors according to claim 1, wherein the hydrophilic group is at least one kind of 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. The additive for electrolytic capacitors according to claim 1 or 2, wherein the polymer (A) is a polymer having the hydrophilic group-containing ethylenically unsaturated monomer (a) as a constituent monomer. The ethylenically unsaturated monomer (a) having a hydrophilic group has a hydroxyl group-containing (meth)acrylic monomer, an acidic group-containing (meth)acrylic monomer, a basic group-containing (meth)acrylic monomer, and the hydroxyl group. Which is at least one selected from the group consisting of alkyl ethers of alkylene oxide adducts to (meth)acrylic monomers having
The alkylene oxide added to the (meth)acrylic monomer having a hydroxyl group is an alkylene oxide having 2 to 3 carbon atoms,
The (meth)acrylic monomer having a hydroxyl group is 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 the hydroxy group having 4 to 12 carbon atoms. At least one selected from the group consisting of alkylene oxide adducts to alkyl (meth)acrylates,
The (meth)acrylic monomer having an acidic group is 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. At least one,
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. The additive for electrolytic capacitors according to. The ratio of the total weight of the hydrophilic group-containing ethylenically unsaturated monomer (a) constituting the polymer (A) is 50 to 100% by weight based on the weight of all the monomers constituting the polymer (A). The additive for electrolytic capacitors according to claim 3 or 4. The additive for electrolytic capacitors according to claim 1, wherein the polymer (A) has a number average molecular weight of 1,000 to 500,000. The glass transition point of a polymer (A) is -100-80 degreeC, The additive for electrolytic capacitors in any one of Claims 1-6. A conductive polymer dispersion liquid containing the additive for electrolytic capacitors according to claim 1. An electrolytic solution containing the additive for electrolytic capacitors according to claim 1. An electrolytic capacitor containing the additive for electrolytic capacitors according to claim 1.