JP2006108650A - Electrolyte for electrolytic capacitor, and electrolytic capacitor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit an increase of ESR with time progress in an electrolytic capacitor using a conductive separator. <P>SOLUTION: In the electrolytic capacitor including in a case a capacitive element formed by winding a pair of electrodes through a conductive separator (E) 4 on a front surface of which a conductive polymer layer (F) containing dopant agent (H) is formed and by impregnating between a pair of the electrodes with electrolyte for the electrolytic capacitor, there are used an acid component (D) which is an electrolytic component contained in the electrolyte for the electrolytic capacitor, and the electrolyte or the like for the electrolytic capacitor in which the acid component (D) is excess in a mole ratio with a base component (C). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrolytic capacitor including a conductive separator having a conductive polymer layer formed on a surface thereof, and an electrolytic solution for an electrolytic capacitor used therefor.

  With the increase in frequency of various electronic devices, there is a demand for a large-capacity electrolytic capacitor having excellent equivalent series resistance (hereinafter also referred to as ESR) characteristics in a high frequency region.

  In recent years, an electrolytic capacitor having a structure in which a conductive separator having a conductive polymer layer formed on the surface thereof is disposed between a pair of electrodes has been proposed as the electrolytic capacitor.

  For example, Patent Document 1 below proposes improving the ESR characteristics of an electrolytic capacitor by making a separator of the electrolytic capacitor conductive with a conductive polymer.

  On the other hand, electrolytic solutions for electrolytic capacitors (hereinafter, also simply referred to as “electrolytic solutions”) have been developed for improving the energy loss and ESR characteristics of electrolytic capacitors. As the electrolytic solution, an electrolytic solution having high electrical conductivity, specifically, a quaternary carboxylate of a compound having an alkyl-substituted amidine group as described in Patent Document 2 below, for example, is used as the electrolyte. So-called amidine electrolytes have been proposed. However, it is still insufficient to improve the ESR characteristics and the like only by using the electrolytic solution having high conductivity.

In addition, the increase in ESR with the passage of time that occurs in an electrolytic capacitor including a conductive separator is accompanied by the gradual escape of the dopant agent from the conductive polymer layer containing the dopant agent in the electrolyte (so-called dedoping phenomenon). There is a problem that the conductive polymer deteriorates and the electrical conductivity of the conductive polymer layer gradually decreases.
JP-A-1-90517 International Publication No. 95/15572 Pamphlet

  It is an object of the present invention to provide an electrolytic capacitor that can suppress an increase in ESR with the passage of time that occurs in an electrolytic capacitor including a conductive separator, and an electrolytic solution for an electrolytic capacitor used therefor.

  As a result of intensive studies on means for solving the above-mentioned problems, it has been found that the problem can be solved by the following means.

  That is, in the invention of claim 1, a pair of electrodes is wound through a conductive separator (E) having a conductive polymer layer (F) containing a dopant agent (H) formed on the surface, and the electrodes An electrolytic solution for an electrolytic capacitor used in an electrolytic capacitor in which a capacitor element formed by impregnating an electrolytic solution between a pair is built in a case, wherein the acid is an electrolyte component contained in the electrolytic solution for electrolytic capacitor An electrolytic solution for electrolytic capacitors, wherein the acid component (D) is excessive in the molar ratio of the component (D) to the base component (C).

  The invention of claim 2 is the electrolytic solution for electrolytic capacitors according to claim 1, wherein the electrolytic solution for electrolytic capacitors contains an antioxidant.

  The invention according to claim 3 is the electrolytic solution for an electrolytic capacitor according to claim 1 or 2, wherein the acid component (D) contains an organic carboxylic acid (D1).

  According to a fourth aspect of the invention, the organic carboxylic acid (D1) is at least one selected from the group consisting of phthalic acid, trimellitic acid, pyromellitic acid, maleic acid, salicylic acid, benzoic acid, and resorcinic acid. The electrolytic solution for an electrolytic capacitor according to claim 3.

  The invention according to claim 5 is characterized in that the electrolytic solution for electrolytic capacitors contains a compound (C1) having an alkyl-substituted amidine group as the base component (C). The electrolytic solution for an electrolytic capacitor according to item 1.

  The invention according to claim 6 is the electrolytic solution for an electrolytic capacitor according to any one of claims 1 to 5, wherein the pH is 2 to 7.

  In the invention of claim 7, a pair of electrodes is wound through a conductive separator (E) having a conductive polymer layer (F) containing a dopant agent (H) formed on the surface, and the electrodes An electrolytic capacitor in which a capacitor element formed by impregnating an electrolytic solution between a pair is built in a case, wherein the electrolytic solution is an electrolytic solution for an electrolytic capacitor according to any one of claims 1 to 6. It is an electrolytic capacitor characterized by being.

  By using the electrolytic solution for electrolytic capacitors according to claim 1, ESR of the obtained electrolytic capacitor can be reduced. Moreover, since the dedoping phenomenon from the conductive separator (E) can be suppressed, an increase in ESR with time in the electrolytic capacitor can be suppressed. Accordingly, it is possible to provide a long-life and highly reliable electrolytic capacitor.

  Moreover, by using the electrolytic solution for electrolytic capacitors containing an antioxidant, it is possible to suppress the oxidative deterioration of the conductive polymer layer, and to further suppress the increase in ESR with the passage of time of the electrolytic capacitor, The effect of the acid component in the electrolyte solution being excessive can be increased (claim 2).

  The acid component (D) contained in the electrolytic solution for electrolytic capacitors is composed of an organic carboxylic acid (D1), particularly phthalic acid, trimellitic acid, pyromellitic acid, maleic acid, salicylic acid, benzoic acid, and resorcinic acid. When at least one selected from the group is contained, corrosion of the electrode can be suppressed (claims 3 and 4).

  Further, the inclusion of the compound (C1) having an alkyl-substituted amidine group as the base component (C) contained in the electrolytic solution for electrolytic capacitors increases the conductivity of the electrolytic solution, reduces the resistance of the electrolytic solution, and reduces the ESR. This is preferable from the viewpoint of high characteristics (claim 5).

  Moreover, it is preferable that the pH of the electrolytic solution for electrolytic capacitors is 2 to 7 because the anionized dopant agent does not form an ion pair with the base component in the electrolytic solution, so that de-doping is suppressed. (Claim 6).

  And the electrolytic capacitor of Claim 7 using the said electrolyte solution for electrolytic capacitors is excellent in ESR characteristic. In addition, since the dedoping phenomenon from the conductive separator (E) can be suppressed, an increase in ESR over time can be suppressed. Therefore, the electrolytic capacitor has a long life and high reliability.

  A first embodiment of an electrolytic solution for an electrolytic capacitor and an electrolytic capacitor using the same according to the present invention will be described with reference to FIG.

  FIG. 1 is a partial cross-sectional perspective view showing an example of the configuration of the electrolytic capacitor in the present invention.

  The electrolytic capacitor shown in FIG. 1 includes an anode electrode 2 and a cathode electrode 3 made of aluminum foil as a pair of electrodes. The anode electrode 2 and the cathode electrode 3 are wound with a conductive separator (E) 4 interposed therebetween, and a capacitor element is formed by impregnating the electrolytic solution for an electrolytic capacitor of the present invention between the electrodes.

  The capacitor element is built in a case 1 made of bottomed cylindrical aluminum, and the opening of the case 1 is sealed with a sealing material 6. The anode electrode 2 and the cathode electrode 3 are connected to an external lead 7 that penetrates the sealing material 6 and led out to the outside. The insulating seat plate 8 is provided for surface mounting the electrolytic capacitor.

  A conceptual diagram showing the configuration of the capacitor element is shown in FIG.

  In FIG. 2, 2 and 3 are electrodes, 4 is a conductive separator (E), 5 is an electrolytic solution for an electrolytic capacitor, 9 is a separator substrate (G), 10 is a dopant agent (H), and 10a is an electrolytic for an electrolytic capacitor. A dopant agent 11 that has escaped into the liquid indicates a conductive polymer layer (F).

  The conductive separator (E) 4 is obtained by forming a conductive polymer layer (F) 11 containing a dopant agent (H) 10 on both surfaces of a separator substrate (G) 9. Since the conductive polymer layer (F) 11 is formed on the surface and pores of the separator base material (G) 9, and the conductive separator (E) 4 is made conductive, the separator base material (G) 9 itself The resistance is lower than.

  As a specific example of the conductive separator (E) 4, for example, a dopant agent (H) 10 such as 1-naphthalenesulfonic acid is contained on both surfaces of the separator base material (G) 9 such as a mixed wet nonwoven fabric. What formed the conductive polymer layer (F) 11 which consists of polypyrrole is mentioned.

  In FIG. 2, the conductive separator (E) 4 is shown as a structure in which the separator base material (G) 9 is sandwiched between the conductive polymer layers (F) 11, but this is schematically shown for convenience of explanation. Specifically, for example, when the separator base material (G) 9 is a mixed paper wet nonwoven fabric, the conductive polymer layer (F) 11 is formed on the fiber surface of the mixed wet paper nonwoven fabric. It is what.

  Examples of the wet mixed nonwoven fabric include, for example, a polyethylene terephthalate polyester fiber having 3,5-dicarbomethoxybenzenesulfonic acid as a copolymerization component and a fiber mainly composed of polyethylene terephthalate polyester fiber having diethylene glycol as a copolymerization component; And wet mixed non-woven fabrics.

  The conductive polymer layer (F) 11 containing 1-naphthalenesulfonic acid as the dopant agent (H) 10 was mixed with ammonium persulfate, 1-naphthalenesulfonic acid, water and alcohol in the mixed wet nonwoven fabric. An oxidant solution is attached, and pyrrole, which is a monomer, and an oxidant are vapor-phase polymerized to form the surface of the mixed wet-laid nonwoven fabric.

  As the separator substrate (G) 9, sheet-like insulators such as manila paper, kraft paper, cloth, or a polymer film can be used in addition to the non-woven fabric such as the above-described mixed-wet non-woven fabric.

  On the other hand, as the conductive polymer constituting the conductive polymer layer (F) 11, one or two types forming a polymer having a conjugated double bond (hereinafter also referred to as a conjugated double bond polymer). A conductive polymer obtained by polymerizing the above monomers is used.

  Examples of the monomer include the following compounds (1) to (4) having 2 to 30 or more carbon atoms.

(1) Aliphatic triple bond compounds; acetylene, 1,6-heptadiyne and the like;
(2) Aromatic conjugated compounds; benzene, naphthalene, anthracene, etc .;
(3) Heteroatom-containing conjugated compounds; heterocyclic compounds such as pyrrole, thiophene, furan, and ethylenedioxythiophene; non-heterocyclic compounds such as aniline, sulfonated aniline, and diphenyl sulfide.

  (4) The hydrogen atom of (1) to (3) is an alkyl group having 1 to 20 carbon atoms (for example, methyl, ethyl, lauryl, stearyl group, etc.), an aryl group having 6 to 26 carbon atoms (phenyl, naphthyl group) Etc.) and the like.

  These monomers may be used alone or in combination of two or more. Among these, the heteroatom-containing conjugated compound (3) is preferable, more preferably a heterocyclic compound and aniline, and particularly preferably pyrrole, thiophene, ethylenedioxythiophene and aniline.

  Preferable examples of the conductive polymer constituting the conductive polymer layer (F) 11 include at least one selected from the group consisting of polypyrrole, polythiophene, polyethylenedioxythiophene, and polyaniline.

  In general, the conjugated double bond polymer contains a dopant agent (H) 10 for p-type or n-type doping.

  Doping (or dope) is a conjugated double bond polymer by containing an electron-accepting or electron-donating compound (dopant agent (H) 10) that imparts conductivity to the conjugated double bond polymer. And the separator base material (G) 9 are promoted to transfer charges and increase the conductivity of the conjugated double bond polymer.

  For example, p-type doping of an electron-accepting dopant agent to a conjugated double bond polymer removes some of the electrons in the conjugated orbital π orbital of the conjugated system to generate carriers, and the conjugated double bond polymer The electrical conductivity of can be improved.

  In particular, the conductive polymer layer (F) 11 in the present invention is preferably formed of a conductive polymer obtained by p-type doping the conjugated double bond polymer with the dopant agent (H) 10.

  The conductive separator (E) 4 is applied or impregnated with a liquid obtained by dissolving or dispersing the conductive polymer constituting the conductive polymer layer (F) 11 in the separator substrate (G) 9. It can be produced by volatilizing the medium.

  The conductive separator (E) 4 is polymerized in situ using a monomer in the presence of the separator substrate (G) 9 to form a conductive polymer on the surface of the separator substrate (G) 9. Can also be produced.

  The in-situ polymerization means is preferably a chemical polymerization means using an oxidizing agent. At that time, the conductive polymer layer (F) 11 is formed by applying or impregnating the separator base material (G) 9 with one treatment liquid in which an oxidizing agent, a polymerizable monomer, and a dopant agent coexist. In addition, the monomer solution and the solution containing the oxidizing agent and the dopant agent are separately prepared, and each separator is sequentially coated or impregnated on the separator base material (G) 9 to provide conductivity. A method of forming the polymer layer (F) 11 may be used.

  Alternatively, the conductive polymer layer (F) 11 may be formed by previously attaching an oxidizing agent to the separator substrate (G) 9 and applying or impregnating the monomer solution.

  Further, an oxidizing agent is attached to the separator base material (G) 9 in advance, and monomer vapor is brought into contact with the separator base material (G) 9 for polymerization to form a conductive polymer layer (F) 11. May be.

  The method for p-type doping the conjugated double bond polymer with the dopant agent (H) 10 is not particularly limited. For example, a separator base material having a conjugated double bond polymer formed on the surface is used as the dopant agent (H) 10. And a method of immersing in the solution.

  In the present invention, examples of the dopant agent (H) 10 for p-type doping include organic sulfonic acids, fluorocarboxylic acids, boron complexes, halogenated inorganic acids and the like, which are electron accepting compounds.

  Specific examples of the organic sulfonic acid include the following compounds.

  (1) Saturated and unsaturated aliphatic sulfonic acids having 1 to 30 or more carbon atoms: [Monovalent saturated aliphatic sulfonic acids (methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, isopropylsulfonic acid, butanesulfonic acid , Isobutylsulfonic acid, t-butylsulfonic acid, pentanesulfonic acid, isopentylsulfonic acid, hexanesulfonic acid, nonanesulfonic acid, decanesulfonic acid, undecanesulfonic acid, dodecanesulfonic acid, tridecanesulfonic acid, tetradecanesulfonic acid, n -Octyl sulfonic acid, cetyl sulfonic acid, etc.) monovalent unsaturated aliphatic sulfonic acid (ethylene sulfonic acid, 1-propene-1-sulfonic acid, etc.), divalent or higher aliphatic sulfonic acid (methionic acid, 1, 1-ethanedisulfonic acid, 1,2-ethanedisulfonic acid, 1,1 Propanedisulfonic acid, 1,3-propanedisulfonic acid, polyvinylsulfonic acid, etc.), oxyaliphatic sulfonic acids (isethionic acid, 3-oxy-propanesulfonic acid, etc.), sulfoaliphatic carboxylic acids (sulfoacetic acid, sulfosuccinic acid, etc.) , Sulfoaliphatic carboxylic acid esters (such as di (2-ethylhexyl) sulfosuccinic acid)]

(2) Fluorosulfonic acid RfSO ₃ H (where Rf is a fluoroalkyl group having 1 to 30 carbon atoms): (trifluoromethanesulfonic acid, perfluoroethanesulfonic acid, perfluoropropanesulfonic acid, perfluoroisopropylsulfonic acid, perfluoro Butanesulfonic acid, perfluoroisobutylsulfonic acid, perfluorot-butylsulfonic acid, perfluoropentanesulfonic acid, perfluoroisopentylsulfonic acid, perfluorohexanesulfonic acid, perfluorononanesulfonic acid, perfluorodecanesulfonic acid, perfluorodecanesulfonic acid Fluoroundecanesulfonic acid, perfluorododecanesulfonic acid, perfluorotridecanesulfonic acid, perfluorotetradecanesulfonic acid, perfluoron-octylsulfonic acid, perfluorocetyls Such as acid)

  (3) Aromatic sulfonic acid having 6 to 30 or more carbon atoms: [monovalent aromatic sulfonic acid (benzenesulfonic acid, p-toluenesulfonic acid, o-toluenesulfonic acid, m-toluenesulfonic acid, o- Xylene-4-sulfonic acid, m-xylene-4-sulfonic acid, 4-ethylbenzenesulfonic acid, 4-propylbenzenesulfonic acid, 4-butylbenzenesulfonic acid, 4-dodecylbenzenesulfonic acid, 4-octylbenzenesulfonic acid, 2-methyl-5-isopropylbenzenesulfonic acid, 2-naphthalenesulfonic acid, butylnaphthalenesulfonic acid, t-butylnaphthalenesulfonic acid, 2,4,5-trichlorobenzenesulfonic acid, benzylsulfonic acid, phenylethanesulfonic acid, etc.) Divalent or higher aromatic sulfonic acid (m-benzenedisulfone 1,4-naphthalenedisulfonic acid, 1,5-naphthalenedisulfonic acid, 1,6-naphthalenedisulfonic acid, 2,6-naphthalenedisulfonic acid, 2,7-naphthalenedisulfonic acid, 1,3,6-naphthalenetrisulfone Acid, sulfonated polystyrene, etc.), oxyaromatic sulfonic acid (phenol-2-sulfonic acid, phenol-3-sulfonic acid, phenol-4-sulfonic acid, anisole-o-sulfonic acid, anisole-m-sulfonic acid, phenetole) -O-sulfonic acid, phenetole-m-sulfonic acid, phenol-2,4-disulfonic acid, phenol-2,4,6-trisulfonic acid, anisole-2,4-disulfonic acid, phenetol-2,5-disulfone Acid, 2-oxytoluene-4-sulfonic acid, pyrocatechin-4-sulfonic acid, Latrol-4-sulfonic acid, resorcin-4-sulfonic acid, 2-oxy-1-methoxybenzene-4-sulfonic acid, 1,2-dioxybenzene-3,5-disulfonic acid, resorcin-4,6-disulfone Acid, hydroquinonesulfonic acid, hydroquinone-2,5-disulfonic acid, 1,2,3-trioxybenzene-4-sulfonic acid, etc.), sulfoaromatic carboxylic acid (o-sulfobenzoic acid, m-sulfobenzoic acid, p-sulfobenzoic acid, 2,4-disulfobenzoic acid, 3-sulfophthalic acid, 3,5-disulfophthalic acid, 4-sulfoisophthalic acid, 2-sulfoterephthalic acid, 2-methyl-4-sulfobenzoic acid, 2- Methyl-3,5-disulfobenzoic acid, 4-propyl-3-sulfobenzoic acid, 2,4,6-trimethyl-3-sulfobenzoic acid, 2-methyl- 5-sulfoterephthalic acid, 5-sulfosalicylic acid, 3-oxy-4-sulfobenzoic acid, etc.), thioaromatic sulfonic acid (thiophenol sulfonic acid, thioanisole-4-sulfonic acid, thiophenetol-4-sulfonic acid) Etc.), aromatic sulfonic acids having other functional groups (benzaldehyde-o-sulfonic acid, benzaldehyde-2,4-disulfonic acid, acetophenone-o-sulfonic acid, acetophenone-2,4-disulfonic acid, benzophenone-o-sulfone) Acid, benzophenone-3,3′-disulfonic acid, 4-aminophenol-3-sulfonic acid, anthraquinone-1-sulfonic acid, anthraquinone-1,5-disulfonic acid, anthraquinone-1,8-disulfonic acid, anthraquinone-2 , 6-Disulfonic acid, 2-methylanthraquinone-1 Such as a sulfonic acid)].

Specific examples of the fluorocarboxylic acid include the following compounds.
Fluorocarboxylic acid RfCOOH (Rf is a fluoroalkyl group having 1 to 30 carbon atoms): (trifluoroacetic acid, perfluoropropionic acid, perfluoroisopropionic acid, perfluorobutyric acid, perfluorovaleric acid, perfluorocaproic acid, Fluoroperargonic acid, perfluorocapric acid, perfluoroundecyl acid, perfluorotridecanoic acid, perfluorotetradecanoic acid, perfluoron-octanoic acid, perfluorolauric acid, perfluoropalmitic acid, etc.)

Specific examples of the boron complex include the following compounds.
(1) Alcoholic hydroxyl group-containing compound complex of boric acid; ethylene glycol borate complex, trimethylene glycol borate complex, etc .;
(2) Boric acid carboxyl group-containing compound ester complex; borodisoxalic acid ester complex, borodiglycolic acid ester complex;
(3) Phosphoric acid and / or phosphoric acid ester complex of boric acid; boric acid methyl phosphate complex, boric acid ethyl phosphate complex, etc .; As the details of the boron complex, those described in Japanese Patent No. 2966451 can be used.

Specific examples of the halogenated inorganic acid include the following compounds.
_{HF, HPF 6, HBF 4,} HAsF 6, HSbF 6, HAlF 4, HTaF 6, HNbF 6, H 2 SiF 6, HCl, HPCl 6, HBCl 4, HAsCl 6, HSbCl 6, HAlCl 4, HTaCl 6, HNbCl 6 , H ₂ SiCl ₆ , HBr, HPBr ₆ , HBBr ₄ , HAsBr ₆ , HSbBr ₆ , HAlBr ₄ , HTaBr ₆ , HNbBr ₆ , H ₂ SiBr ₆ , HClO _{4 and the} like.

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

Of these, preferred are methanesulfonic acid, t-butylsulfonic acid, pentanesulfonic acid, dodecylbenzenesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 4-ethylbenzenesulfonic acid, 4-butylbenzenesulfonic acid, 4-octylbenzenesulfonic acid, 2-naphthalenesulfonic acid, butylnaphthalenesulfonic acid, anthraquinone-2-sulfonic acid, di (2-ethylhexyl) sulfosuccinic acid, o-sulfobenzoic acid, perfluorobutanesulfonic acid, perfluoropentanesulfone Acid, trifluoroacetic acid, perfluorobutyric acid, borodisuccinic acid ester complex, borodiglycolic acid ester complex, HBF ₄ , HAlF ₄ , HBCl ₄ , HBBr ₄ , and more preferable are t-butylsulfonic acid, pentanes They are sulfonic acid, p-toluenesulfonic acid, 4-butylbenzenesulfonic acid, 2-naphthalenesulfonic acid, butylnaphthalenesulfonic acid, anthraquinone-2-sulfonic acid, perfluorobutanesulfonic acid, and perfluoropentanesulfonic acid.

  Next, the electrolytic solution components of the electrolytic solution for electrolytic capacitors will be described in detail.

  The electrolytic solution for electrolytic capacitors includes an organic solvent or the like as an electrolyte component (acid component and base component) such that the acid component (D) is excessive in the molar ratio of the acid component (D) and the base component (C). It is prepared by dissolving in a solvent.

  When a conventional electrolytic solution is used in an electrolytic capacitor using a conductive separator (E) 4 on which a conductive polymer layer (F) 11 containing a dopant agent (H) 10 is formed as a separator, the conductive polymer layer (F) A de-doping phenomenon in which the dopant agent escapes into the electrolytic solution from 11, and the anionic dopant agent in the electrolytic solution makes the electrolytic solution acidic.

  However, when the electrolytic solution for electrolytic capacitors of the present invention is used, the above-described dedoping phenomenon can be suppressed. That is, the acid component (D) in the electrolyte component is excessive in molar ratio with respect to the base component (C) in advance to lower the pH value of the electrolyte solution, thereby reducing the pH value of the anionized dopant agent and the electrolyte solution. Since the pH value is close, the dedoping phenomenon can be suppressed. Therefore, an increase in ESR due to the dedoping phenomenon of the conductive polymer layer (F) can be suppressed, and the life of the electrolytic capacitor can be extended.

  As a method of making the acid component (D) excessive in the molar ratio of the acid component (D) and the base component (C) that are electrolyte components, another acid component is post-added to a general electrolytic solution. Alternatively, a method in which acid is excessive in advance in the electrolytic solution generation stage, or the like is used.

  The ratio of excess acid component (D) in the molar ratio of acid component (D) to base component (C) is 1: 1.05 to 1: 1.5 (molar ratio in the electrolyte). The base component (C) is preferably about the acid component (D)). When the acid component (D) is too small in the above ratio, the anionized dopant agent tends to form an ion pair with the base component in the electrolytic solution, so that the dedoping phenomenon is promoted from the conductive polymer. Tend. Moreover, since the electrical conductivity of electrolyte solution falls when there is too much, there exists a tendency for an ESR characteristic to deteriorate.

  When organic sulfonic acid is used as the acid component (D) of the electrolyte component and the organic sulfonic acid is used as the dopant agent (H) contained in the conductive polymer layer (F), both are the same component. Therefore, it is difficult for dedoping to occur, and a decrease in the reliability of the electrolytic capacitor can be suppressed. However, since the organic sulfonic acid exhibits strong acidity, depending on the amount added, the electrode may be corroded. Therefore, it is more preferable to use organic carboxylic acid (D1) such as aromatic carboxylic acid or aliphatic carboxylic acid instead of organic sulfonic acid. When the organic carboxylic acid (D1) such as aromatic carboxylic acid or aliphatic carboxylic acid is used as the acid component (D), the corrosion can be suppressed.

  As organic carboxylic acid (D1), aromatic carboxylic acid: (for example, phthalic acid, salicylic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, benzoic acid, resorcinic acid, cinnamic acid, naphthoic acid), fat Aromatic carboxylic acids: ([saturated carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, Tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, methylmalonic acid, ethylmalonic acid, propylmalonic acid, butylmalonic acid, pentylmalonic acid, hexylmalonic acid, dimethylmalonic acid, diethylmalonic acid, methylpropylmalonic acid, methyl Butylmalonic acid, ethylpropylmalonic acid, dipropylmalonic acid, Lusuccinic acid, ethyl succinic acid, 2,2-dimethyl succinic acid, 2,3-dimethyl succinic acid, 2-methyl glutaric acid, 3-methyl glutaric acid, 3-methyl-3-ethyl glutaric acid, 3,3-diethyl glutar Acid, methylsuccinic acid, 2-methylglutaric acid, 3-methylglutaric acid, 3,3-dimethylglutaric acid, 3-methyladipic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid, formic acid, acetic acid , Propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, behenic acid, undecanoic acid], [unsaturated carboxylic acids such as maleic acid, Fumaric acid, itaconic acid, acrylic acid, methacrylic acid, oleic acid]) and the like. These may be used alone or in combination of two or more. Among these, phthalic acid, trimellitic acid, pyromellitic acid, maleic acid, salicylic acid, benzoic acid, resorcinic acid, and the like are preferably used because they have high electrical conductivity and are thermally stable.

  On the other hand, as the base component (C) of the electrolyte component, for example, an imidazole compound, a benzimidazole compound, an alicyclic amidine compound (pyrimidine compound, imidazoline compound) which is a compound having an alkyl-substituted amidine group, the alkyl-substituted A quaternary salt compound of a compound having an amidine group, specifically, for example, an imidazolium compound, a benzimidazolium compound, an alicyclic amidinium compound quaternized with an alkyl group having 1 to 11 carbon atoms or an arylalkyl group (Pyrimidinium compound, imidazolinium compound) and the like.

  Examples of the compound having an alkyl-substituted amidine group include imidazole compounds such as 1-methylimidazole, 1,2-dimethylimidazole, and 1-ethyl-2-methylimidazole, 1-methylbenzimidazole, and 1,2-dimethylbenzoate. Benzimidazole compounds such as imidazole and 1-ethyl-2-methylbenzimidazole, pyrimidine compounds such as 1-methylpyrimidine and 1-ethylpyrimidine, 1-methylimidazoline, 1,2-dimethylimidazoline, 1,2,4-trimethyl Examples include imidazoline compounds such as imidazoline.

  Examples of the quaternary salt compound of the compound having an alkyl-substituted amidine group include 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1,2,3. -Trimethylimidazolium, 1,2,3,4-tetramethylimidazolium, 1,3-dimethyl-2-ethylimidazolium, 1,2-dimethyl-3-ethyl-imidazolium, 1,2,3-triethyl Imidazolium, 1,2,3,4-tetraethylimidazolium, 1,3-dimethyl-2-phenylimidazolium, 1,3-dimethyl-2-benzylimidazolium, 1-benzyl-2,3-dimethyl-imidazole Rium, 4-cyano-1,2,3-trimethylimidazolium, 3-cyanomethyl-1,2-dimethylimidazolium 2-cyanomethyl-1,3-dimethyl-imidazolium, 4-acetyl-1,2,3-trimethylimidazolium, 3-acetylmethyl-1,2-dimethylimidazolium, 4-methylcarbooxymethyl-1, 2,3-trimethylimidazolium, 3-methylcarbooxymethyl-1,2-dimethylimidazolium, 4-methoxy-1,2,3-trimethylimidazolium, 3-methoxymethyl-1,2-dimethylimidazolium, 4-formyl-1,2,3-trimethylimidazolium, 3-formylmethyl-1,2-dimethylimidazolium, 3-hydroxyethyl-1,2-dimethylimidazolium, 4-hydroxymethyl-1,2,3 -Trimethylimidazolium, 2-hydroxyethyl-1,3-dimethylimidazolium, etc. Benzimidazolium compounds such as imidazolium compounds, 1,3-dimethylbenzimidazolium, 1,2,3-trimethylbenzimidazolium, 1-ethyl-2,3-dimethylbenzimidazolium, 1,3-dimethyl-1 , 4,5,6-tetrahydropyrimidinium, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 1,2,3,4-tetramethyl-1,4,5 6-tetrahydropyrimidinium, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidinium, 8-methyl-1,8-diazabicyclo [5,4,0] -7- Undecenium, 5-methyl-1,5-diazabicyclo [4,3,0] -5-nonenium, 4-cyano-1,2,3-trimethyl-1,4,5,6-tetrahydropyri Midinium, 3-cyanomethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 2-cyanomethyl-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 4- Acetyl-1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-acetylmethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 4-methyl Carbooxymethyl-1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-methylcarbooxymethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium 4-methoxy-1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-methoxymethyl-1,2-dimethyl-1,4,5,6-teto Hydropyrimidinium, 4-formyl-1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 3-formylmethyl-1,2-dimethyl-1,4,5,6-tetrahydro Pyrimidinium, 3-hydroxyethyl-1,2-dimethyl-1,4,5,6-tetrahydropyrimidinium, 4-hydroxymethyl-1,2,3-trimethyl-1,4,5,6-tetrahydro Pyrimidinium compounds such as pyrimidinium, 2-hydroxyethyl-1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium, 1,2,3,4-tetramethylimidazolinium, 4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2,4-diethylimidazolinium, 1,2-dimethyl-3,4-diethylimidazolinium 1-methyl-2,3,4-triethylimidazolinium, 1,2,3,4-tetraethylimidazolinium, 1,2,3-trimethylimidazolinium, 1,3-dimethyl-2-ethyl Imidazolinium, 1-ethyl-2,3-dimethylimidazolinium, 1,2,3-triethylimidazolinium, 4-cyano-1,2,3-trimethylimidazolinium, 3-cyanomethyl-1,2 -Dimethylimidazolinium, 2-cyanomethyl-1,3-dimethylimidazolinium, 4-acetyl-1,2,3-trimethylimidazolinium, 3-acetylmethyl-1,2-dimethylimidazolinium, 4- Methylcarbooxymethyl-1,2,3-trimethylimidazolinium, 3-methylcarbooxymethyl-1,2-dimethylimidazolinini , 4-methoxy-1,2,3-trimethylimidazolinium, 3-methoxymethyl-1,2-dimethylimidazolinium, 4-formyl-1,2,3-trimethylimidazolinium, 3-formylmethyl -1,2-dimethylimidazolinium, 3-hydroxyethyl-1,2-dimethylimidazolinium, 4-hydroxymethyl-1,2,3-trimethylimidazolinium, 2-hydroxyethyl-1,3-dimethyl Examples include imidazolinium compounds such as imidazolinium.

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

  Among these, compounds having an alkyl-substituted amidine group (C1), particularly 1-ethyl-3-methylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1,2,3,4-tetramethyl Imidazolium and imidazolinium compounds such as imidazolinium, 1,2,3-trimethylimidazolinium, 1-ethyl-2,3-dimethylimidazolinium, etc. have high electrical conductivity, so the resistance due to the electrolyte is reduced. From the point that the ESR characteristic becomes high.

  The electrolytic solution for electrolytic capacitors may further contain an antioxidant.

  Examples of the antioxidant include aromatic compounds, amine compounds, silane compounds, quinone compounds, and carboxylic acid compounds.

  As the antioxidant, aromatic compounds such as phenol, methylphenol, ethylphenol, pyrogallol, hydroquinone, pyrocatechol, tocophenol, butylhydroxyanisole, dibutylhydroxytoluene, benzoic acid, salicylic acid, resorcinic acid, and benzotriazole were used. In this case, the anti-oxidation effect is particularly high because the electrons contributing to oxidative degradation are likely to be resonantly stabilized. Therefore, it is particularly preferable because it is possible to suppress a decrease in electrical conductivity of the conductive separator (E) 4 due to oxidation.

  By adding the antioxidant, it is possible to suppress the oxidative deterioration of the conductive polymer layer (F) 11 and to further suppress the increase in ESR with the passage of time of the electrolytic capacitor. The effect due to the excess of the acid component can be increased.

  The electrolytic solution for electrolytic capacitors may further contain other additives.

  Examples of the additive include phosphorus compounds such as phosphate esters, complex compounds of boric acid, boric acid and mannitol, polysaccharides such as sorbit, and complex compounds of boric acid and polyhydric alcohols such as ethylene glycol and glycerin. And boric acid compounds such as o-nitrobenzoic acid, m-nitrobenzoic acid, p-nitrobenzoic acid, nitro compounds such as o-nitrophenol, m-nitrophenol, and p-nitrophenol.

  The additive may be preferable from the viewpoint of increasing the spark voltage of the electrolytic solution of the present invention.

  Examples of the organic solvent for dissolving the acid component (D), the base component (C), the antioxidant, the additive and the like include the following.

  For example, alcohols (methanol, ethanol, propanol, butanol, cyclobutanol, cyclohexanol, ethylene glycol, propylene glycol, glycerin, methyl cellosolve, ethyl cellosolve, methoxypropylene glycol), ether-based aprotic organic solvents [ethylene glycol Monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monophenyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether) Amides (N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, etc.), nitriles [acetonitrile, propionitrile, Butyronitrile, acrylonitrile, methacrylonitrile, benzonitrile], lactones (γ-butyrolactone, β-butyrolactone, α-valerolactone, γ-valerolactone, etc.), carbonates (ethylene carbonate, propion carbonate, butylene carbonate, dimethyl carbonate, diethyl) Carbonate], sulfoxides [sulfolane, 3-methylsulfolane, dimethyl sulfoxide] and the like. These may be used alone or in combination of two or more.

  The electrolytic solution of the present invention can be obtained by dissolving the various components in the solvent.

  The content ratio of the acid component (D) and the base component (C) in the electrolytic solution of the present invention is preferably 5 to 80% by mass, more preferably 10 to 60% by mass, and particularly preferably 15 to 40% by mass. .

  The pH of the electrolytic solution for electrolytic capacitors is preferably 2 to 7, more preferably 4 to 7, and particularly preferably 5 to 7. If the pH is too low, corrosion due to dissolution of the electrode material is remarkably advanced, making it difficult to ensure reliability. If the pH is too high, excess base components form ion pairs. Therefore, the reaction for extracting the dopant is promoted.

  The electrolytic capacitor of the present invention obtained by using such an electrolytic solution for electrolytic capacitors is a conductive separator having a conductive polymer layer (F) containing a dopant agent (H) as a pair of electrode pairs on the surface. (E) is an electrolytic capacitor in which a capacitor element formed by impregnating an electrolytic solution between the pair of electrodes is formed in a case, and has excellent ESR characteristics, and also has a conductive separator (E) Therefore, an increase in ESR over time can be suppressed. Therefore, the electrolytic capacitor has a long life and high reliability.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to these.

  A method for manufacturing the electrolytic capacitor in this example will be described below.

[Manufacture of electrolytic capacitors]
First, a p-type doping conductive separator (E) was manufactured as follows.

A Manila paper separator having a size of 6 × 180 (mm), a thickness of 40 μm, and a density of 0.4 g / cm ³ was prepared as a separator substrate (G). Then, the separator substrate (G) is sequentially immersed in an aqueous solution containing 0.1 M pyrrole aqueous solution and 0.03 M p-toluenesulfonic acid at atmospheric pressure and room temperature to wash the reaction residue, followed by drying, p -A p-type doped conductive separator (E) having a p-type doped conductive polymer layer (F) made of polypyrrole doped with toluenesulfonic acid formed on the surface thereof was obtained. The sheet resistance of the obtained p-type doping conductive separator (E) was 5 × 10 ⁻¹ (Ω).

  Then, a pair of electrodes consisting of an anodized foil having a dielectric oxide film and a cathode foil was wound through the p-type doping conductive separator (E). Next, a capacitor element is formed by immersing the wound electrode pair in an electrolytic solution for an electrolytic capacitor to be described later, and the capacitor element is built in a case, and a sealing rubber made of peroxide-vulcanized butyl rubber To obtain an aluminum electrolytic capacitor.

  The obtained aluminum electrolytic capacitor was subjected to an aging treatment for applying a voltage load of 8.0 V at 105 ° C. for 1 hour as a finishing treatment.

  In this way, a surface mount type aluminum electrolytic capacitor (rated voltage: 10 V—capacitance: 470 μF, size: φ10 mm · L10.5 mm) was obtained.

  Moreover, the measuring method of ESR in this invention is shown below.

[ESR measurement method]
The ESR was measured according to the test method for aluminum electrolytic capacitors defined by JIS C 5102.

  The measurement apparatus and conditions were ESR measured by the AC bridge method using a Hewlett Packard PRECISION LCR METER 4284A under conditions of a frequency of 100 kH and a voltage of 0.5 Vrms.

(Examples 1 to 8 and Comparative Examples 1 and 2)
As electrolytic solutions for electrolytic capacitors, electrolytic solutions having the compositions of Examples 1 to 8 and Comparative Examples 1 and 2 shown in Table 1 were prepared.

  And the electrolytic capacitor was manufactured using each said electrolyte solution.

  With respect to the obtained electrolytic capacitor, ESR when treated at a high temperature with a charge load of 6.3 V for 1000 hours in an atmosphere of 105 ° C., and ESR before treatment (initial ESR) were measured by the measurement method.

  The results are shown in Table 1.

  In Table 1, when Examples 1-8 are compared with Comparative Examples 1 and 2, in the molar ratio of the acid component (D) and the base component (C) that are electrolyte components contained in the electrolytic solution for electrolytic capacitors, It can be seen that the change in ESR before and after the high temperature treatment of the electrolytic capacitors of Examples 1 to 8 in which the acid component (D) is excessive is much smaller than the change in Comparative Examples 1 and 2.

  In particular, in the electrolytic capacitors of Example 7 and Example 8 to which an antioxidant was added, the ESR hardly changed before and after the high temperature treatment. The reason for this is not clear at present, but probably the acid component and the antioxidant form a hydrogen bond, which stabilizes the electron resonance structure of the aromatic compound. It is thought to be based on the principle that performance increases.

  The electrolytic capacitor according to the present invention can suppress the dedoping phenomenon in the conductive separator (E) and suppress an increase in ESR with the passage of time of the electrolytic capacitor, and is particularly useful as an electrolytic capacitor used in a high frequency region. .

The partial cross section perspective view which showed the structure of the electrolytic capacitor by one Embodiment of this invention. The conceptual diagram which shows the structure of the capacitor | condenser element of the electrolytic capacitor by one Embodiment of this invention.

Explanation of symbols

1 Case 2, 3 Electrode 4 Conductive separator (E)
5 Electrolytic Solution 7 Lead 8 Insulating Seat 9 Separator Base Material (G)
10 Dopant agent (H)
11 Conductive polymer layer (F)

Claims (7)

A pair of electrode pairs are wound through a conductive separator (E) having a conductive polymer layer (F) containing a dopant agent (H) formed on the surface, and an electrolyte is impregnated between the electrode pairs. An electrolytic solution for an electrolytic capacitor used for an electrolytic capacitor having a capacitor element formed in a case,
An electrolytic solution for an electrolytic capacitor, wherein the acid component (D) is excessive in a molar ratio of the acid component (D) and the basic component (C) that are electrolyte components contained in the electrolytic capacitor electrolytic solution.   The electrolytic solution for electrolytic capacitors according to claim 1, wherein the electrolytic solution for electrolytic capacitors contains an antioxidant.   The electrolytic solution for an electrolytic capacitor according to claim 1 or 2, wherein the acid component (D) contains an organic carboxylic acid (D1).   The organic carboxylic acid (D1) is at least one selected from the group consisting of phthalic acid, trimellitic acid, pyromellitic acid, maleic acid, salicylic acid, benzoic acid, and resorcinic acid. Electrolyte for electrolytic capacitors as described.   The electrolytic solution for electrolytic capacitors according to any one of claims 1 to 4, wherein the electrolytic solution for electrolytic capacitors contains a compound (C1) having an alkyl-substituted amidine group as the base component (C). liquid.   pH is 2-7, Electrolyte for electrolytic capacitors of any one of Claims 1-5 characterized by the above-mentioned. A pair of electrode pairs are wound through a conductive separator (E) having a conductive polymer layer (F) containing a dopant agent (H) formed on the surface, and an electrolyte is impregnated between the electrode pairs. An electrolytic capacitor in which a capacitor element to be formed is built in a case,
The said electrolytic solution is the electrolytic solution for electrolytic capacitors of any one of Claims 1-6, The electrolytic capacitor characterized by the above-mentioned.

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