JP5988831B2 - Electrolytic capacitor manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing an electrolytic capacitor using a conductive polymer as a solid electrolyte.

  Conductive polymers are used as solid electrolytes for electrolytic capacitors such as tantalum electrolytic capacitors, aluminum electrolytic capacitors, and niobium electrolytic capacitors because of their high conductivity.

  As the conductive polymer in this application, for example, those obtained by chemical oxidative polymerization or electrolytic oxidative polymerization of thiophene or a derivative thereof are used.

  As a dopant when performing chemical oxidative polymerization of the above thiophene or a derivative thereof, organic sulfonic acid is mainly used. Among them, aromatic sulfonic acid is said to be suitable, and transition metal is a transition metal. Among them, ferric iron is said to be suitable, and usually a ferric salt of aromatic sulfonic acid is used as an oxidizing agent and a dopant in chemical oxidative polymerization of thiophene or a derivative thereof.

  And among the ferric salts of aromatic sulfonic acids, it is said that ferric salts of toluene sulfonic acid and ferric salts of methoxybenzene sulfonic acid are particularly useful, and conductive polymers using them. It can be synthesized by mixing those oxidizing agent / dopant with a polymerizable monomer such as thiophene or a derivative thereof, and is reported to be simple and suitable for industrialization (Patent Document 1, Patent Document) 2).

  However, when the conductive polymer obtained as described above is used as a solid electrolyte of an electrolytic capacitor as it is, it cannot be said that it has sufficiently satisfactory characteristics, and the required characteristics will become higher in the future. It is considered that further improvement of characteristics is necessary for use as a solid electrolyte of an electrolytic capacitor.

  In addition, when the obtained conductive polymer is used as a solid electrolyte of an electrolytic capacitor, the conductive polymer synthesized by the chemical oxidative polymerization method is usually not soluble in a solvent, so that tantalum, niobium, aluminum, etc. It is necessary to form a conductive polymer layer directly on a capacitor element having an anode made of a porous body of a valve metal and a dielectric layer made of an oxide film of the valve metal. In the formation of a conductive polymer layer by a chemical oxidative polymerization method called “polymerization”, the thickness of the conductive polymer layer formed by one “in-situ polymerization” is extremely thin. In order to form a necessary amount of the conductive polymer layer, there has been a problem that the “in-situ polymerization” as described above must be repeated many times.

  Therefore, practical application of a solubilized conductive polymer that does not have such work restrictions has been actively studied (Patent Document 3). According to Patent Document 3, it is reported that a dispersion of a conductive polymer can be obtained by mixing and reacting polystyrene sulfonic acid, ammonium persulfate, iron salt, ethylenedioxythiophene, and the like. However, the conductive polymer obtained as such cannot be said to have sufficiently satisfactory characteristics when used as a solid electrolyte of an electrolytic capacitor as it is, and in the future, electrolytic capacitors that will have increasingly higher required characteristics. In order to use as a solid electrolyte, it is considered that further improvement of characteristics is necessary.

JP 2003-160647 A JP 2004-265927 A Japanese Patent No. 2636968

  In view of the circumstances as described above, an object of the present invention is to provide an electrolytic capacitor having a low ESR (equivalent series resistance), a large capacitance, and a high withstand voltage.

  In the production of a solid electrolytic capacitor using a conductive polymer as a solid electrolyte, the present invention allows the capacitor element to be preliminarily formed with a specific solution before forming the conductive polymer layer constituting the solid electrolyte on the capacitor element. After the treatment and the conductive polymer layer is formed on the capacitor element, the capacitor element on which the conductive polymer layer is formed is post-treated with a specific solution, so that the ESR is low and the capacitance is large. In addition, the inventors have found that an electrolytic capacitor having a high withstand voltage can be obtained, and have completed it.

That is, the first invention of the present application is
In producing an electrolytic capacitor using a conductive polymer as a solid electrolyte, a porous body of at least one kind of valve metal selected from the group consisting of aluminum, tantalum and niobium, and a dielectric layer comprising an oxide film of the valve metal, When a conductive polymer layer is formed on a capacitor element having an organic solvent, as a pretreatment, an organic compound in which a cyclic organic compound having at least one hydroxyl group and a high boiling point solvent having a boiling point of 150 ° C. or higher are dissolved in the capacitor element After impregnating the solvent solution, the drying operation is performed at least once,
The capacitor element after the pre-treatment is impregnated with a dispersion of a conductive polymer obtained by oxidative polymerization of thiophene or a derivative thereof with a polymer anion as a dopant, and then dried at least once, whereby a capacitor is obtained. Form a conductive polymer layer on the device,
The capacitor element after forming the conductive polymer layer is impregnated with an organic solvent solution in which a cyclic organic compound having at least one hydroxyl group is dissolved, and then subjected to post-treatment by performing at least one drying operation. The manufacturing method of the electrolytic capacitor characterized by this.

The second invention of the present application is
In producing an electrolytic capacitor using a conductive polymer as a solid electrolyte, a porous body of at least one kind of valve metal selected from the group consisting of aluminum, tantalum and niobium, and a dielectric layer comprising an oxide film of the valve metal, When a conductive polymer layer is formed on a capacitor element having an organic solvent, as a pretreatment, an organic compound in which a cyclic organic compound having at least one hydroxyl group and a high boiling point solvent having a boiling point of 150 ° C. or higher are dissolved in the capacitor element is used. After impregnating the solvent solution, the drying operation is performed at least once,
The capacitor element after the pre-treatment is impregnated with a dispersion of a conductive polymer obtained by oxidative polymerization of thiophene or a derivative thereof with a polymer anion as a dopant, and then dried at least once, whereby a capacitor is obtained. Form a conductive polymer layer on the device,
By impregnating the capacitor element after forming the conductive polymer layer with a solution in which a cyclic organic compound having at least one hydroxyl group is dissolved in a high boiling point solvent having a boiling point of 150 ° C. or more is performed at least once. The present invention relates to an electrolytic capacitor manufacturing method characterized by post-processing.

  The first invention and the second invention of the present application are the same as the pretreatment, the main treatment, that is, the step of forming the conductive polymer layer on the capacitor element after the pretreatment. Slightly different.

  However, in both the first invention and the second invention, a cyclic organic compound having at least one hydroxyl group is dissolved as a main material in the solution for subsequent processing. In the first invention, Since the solvent is removed by drying at the time of post-processing, the organic solvent such as alcohol is dissolved in the cyclic organic compound having at least one hydroxyl group, but in the second invention, without drying at the time of post-processing, Since the post-treatment solution is left in the electrolytic capacitor as it is, a high boiling point solvent having a boiling point of 150 ° C. or higher is used as a solvent for dissolving the cyclic organic compound having at least one hydroxyl group, and the capacitor is exposed to a high temperature. In this case, the solvent is vaporized in the capacitor so that the capacitor is not adversely affected.

  According to the present invention, it is possible to provide an electrolytic capacitor having a low ESR, a large capacitance, and a high withstand voltage.

  That is, a conductive polymer synthesized using a polymer anion as a dopant is excellent in conductivity, and is suitable for producing an electrolytic capacitor having a low ESR and a large capacitance. Thus, prior to the formation of the conductive polymer layer, the capacitor element is pretreated with a specific pretreatment solution, and after the formation of the conductive polymer layer, with a specific posttreatment solution, Compared to the case where only the main treatment is performed, that is, the case where only the conductive polymer layer is formed on the capacitor element, the combination of the pretreatment and the main treatment, the main treatment and the posttreatment, The ESR is lower, the capacitance is higher, and the withstand voltage is higher than the combination.

  And, in an electrolytic capacitor composed only of a solid electrolyte made of a conductive polymer, there is a tendency that characteristic deterioration such as increase in ESR or decrease in capacitance occurs due to repeated charge and discharge. In the present invention, prior to the formation of the conductive polymer layer on the capacitor element, the capacitor element is pretreated with a specific pretreatment solution, and after the formation of the conductive polymer layer, with a specific posttreatment solution. By post-processing, as shown in Examples 1 to 24 described later, only the main processing, that is, the one in which the conductive polymer layer is formed on the capacitor element, the pre-processing and the main processing are performed. Compared to a combination of these and a combination of the main treatment and post-treatment, the increase in ESR and the decrease in capacitance after charge / discharge are reduced, and the charge / discharge characteristics are improved.

  Like the electrolytic capacitors of Examples 25 to 48 to be described later, those in which the electrolyte contains a conductive solvent are essentially less in characteristic deterioration due to repeated charge and discharge and are excellent in charge and discharge characteristics. Therefore, according to the present invention, it can be said that an electrolytic capacitor having excellent charge / discharge characteristics can be provided.

  In general, in the case where a solvent is included in the electrolyte, there is a concern about a decrease in heat resistance due to the presence of the solvent. However, in the present invention, as shown in the electrolytic capacitors of Examples 25 to 48 described later, The property is excellent.

  And, the conductive polymer obtained by oxidative polymerization of thiophene or its derivatives using the polymer anion as a dopant is because the polymer anion acts as a dispersant during the oxidative polymerization to disperse the monomer and the obtained conductive polymer. In addition to being excellent in heat resistance, since the electrolyte is composed of a solid electrolyte made of a conductive polymer, such as the electrolytic capacitors of Examples 1 to 24 described later, it does not contain a solvent. Excellent in properties. Therefore, according to the present invention, even in the case where the electrolyte is composed only of a solid electrolyte made of a conductive polymer, or when the electrolyte contains a solvent, an electrolysis having excellent heat resistance It can be said that a capacitor can be provided.

  In the present invention, prior to forming the conductive polymer layer on the capacitor element as described above, the cyclic organic compound having at least one hydroxyl group and the high boiling point solvent having a boiling point of 150 ° C. or higher are dissolved in the capacitor element. Pretreatment with the organic solvent solution. Therefore, an organic solvent solution in which a cyclic organic compound having at least one hydroxyl group and a high-boiling solvent having a boiling point of 150 ° C. or higher are dissolved may be referred to as a “pretreatment solution”.

  Examples of the cyclic organic compound having at least one hydroxyl group in the pretreatment solution include phenol, cresol, nitrophenol, cumylphenol, aminophenol, hydroxybenzenecarboxylic acid (that is, hydroxybenzoic acid), sulfosalicylic acid, Dihydroxybenzene, dihydroxybenzenecarboxylic acid (ie, dihydroxybenzoic acid), trihydroxybenzene, trihydroxybenzenecarboxylic acid (ie, trihydroxybenzoic acid), phenolsulfonic acid, cresolsulfonic acid, dihydroxybenzenesulfonic acid, nitrophenolsulfonic acid Hydroxybenzene carboxylic acid alkyl ester (ie hydroxybenzene carboxylic acid methyl ester, hydroxybenzene carboxylic acid ethyl ester) , Hydroxybenzene carboxylic acid propyl ester, hydroxy benzene carboxylic acid butyl ester, etc., particularly preferred are alkyl esters having 1 to 4 carbon atoms), hydroxy nitrobenzene carboxylic acid alkyl esters (that is, hydroxy nitrobenzene carboxylic acid methyl ester, Hydroxy nitrobenzene carboxylic acid ethyl ester, hydroxy nitrobenzene carboxylic acid propyl ester, hydroxy nitrobenzene carboxylic acid butyl ester, etc., particularly preferred are alkyl esters having 1 to 4 carbon atoms), alkoxyphenol (that is, methoxyphenol, ethoxyphenol, Propoxyphenol, butoxyphenol, etc., especially preferred are alkoxyphenols having 1 to 4 carbon atoms) Benzene-based ones, naphthol, nitronaphthol, hydroxynaphthalene carboxylic acid (that is, hydroxynaphthoic acid), dihydroxynaphthol, trihydroxynaphthol, naphtholsulfonic acid, dihydroxynaphtholsulfonic acid, nitronaphtholsulfonic acid, Hydroxanthraquinone, hydroxyindole and the like can be mentioned, and those having only one hydroxyl group are particularly preferable. And these can each be used independently and can also be used together 2 or more types.

  As the cyclic organic compound having at least one hydroxyl group, those having a carboxyl group, those having a nitro group, those having an alkoxy group, and the like are preferable. Examples of the cyclic organic compound having at least one hydroxyl group and having a carboxyl group include, for example, the above hydroxybenzene carboxylic acid, hydroxybenzene carboxylic acid alkyl ester, hydroxynitrobenzene carboxylic acid, hydroxynitrobenzene carboxylic acid alkyl ester, hydroxy And naphthalenecarboxylic acid.

  In addition, as a cyclic organic compound having at least one hydroxyl group and having a nitro group, for example, the above nitrophenol, nitrophenol sulfonic acid, nitronaphthol, nitronaphthol sulfonic acid, etc., and the above carboxyl group Examples thereof include hydroxynitrobenzenecarboxylic acid, hydroxynitrobenzenecarboxylic acid alkyl ester, and the like. Examples of cyclic organic compounds having at least one hydroxyl group and having an alkoxy group include, for example, the above-mentioned methoxyphenol and ethoxyphenol. And alkoxyphenols such as propoxyphenol and butoxyphenol.

  In the cyclic organic compound having at least one hydroxyl group, “having at least one hydroxyl group” may be a case having only one hydroxyl group, or a case having two or more hydroxyl groups. It means that it is good.

  The cyclic organic compound having at least one hydroxyl group as described above lowers the ESR of an electrolytic capacitor using a conductive polymer having a polymer anion as a dopant as a solid electrolyte, increases the capacitance, and increases resistance. It has the effect of increasing the voltage.

  Examples of the high-boiling solvent having a boiling point of 150 ° C. or higher include dimethyl sulfoxide (boiling point: 189 ° C.), γ-butyrolactone (boiling point: 203 ° C.), sulfolane (boiling point: 285 ° C.), N-methylpyrrolidone (boiling point: 202 ° C.), dimethyl sulfolane (boiling point: 233 ° C.), butanediol (boiling point: 230 ° C.), ethylene glycol (boiling point: 198 ° C.), diethylene glycol (boiling point: 244 ° C.), glycerol (that is, glycerin) (boiling point: 290 ° C.) ), Diglycerol (that is, diglycerin) [boiling point: 265 ° C. (15 mmHg)], polyethylene glycol and the like. Polyethylene glycol, such as polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 1500 (the number after polyethylene glycol represents the molecular weight), etc., may have no boiling point under normal pressure. In the present invention, this polyethylene glycol is also included in the category of a high boiling point solvent having a boiling point of 150 ° C. or higher because it does not boil at less than 150 ° C. under normal pressure. In addition, when the boiling point is indicated, the pressure not indicated in parentheses is the boiling point under normal pressure.

  In the organic solvent solution used for the pretreatment of the capacitor element, that is, in the pretreatment solution, a high-boiling solvent having a boiling point of 150 ° C. or higher is allowed to coexist with a cyclic organic compound having at least one hydroxyl group. This lowers the ESR of the capacitor and increases the capacitance. This means that when the pretreatment solution is dried, a part of the high boiling point solvent having a boiling point of 150 ° C. or more remains, and the compatibility between the cyclic organic compound having at least one hydroxyl group and the conductive polymer is improved. It is thought to be due to. That is, in a completely dry state, the compatibility between the cyclic organic compound having at least one hydroxyl group and the conductive polymer is poor, and the characteristics of the electrolytic capacitor cannot be sufficiently improved by the cyclic organic compound having at least one hydroxyl group. However, when a part of the high-boiling solvent having a boiling point of 150 ° C. or more remains, the compatibility between the cyclic organic compound having at least one hydroxyl group and the conductive polymer is improved, so that at least one hydroxyl group is present. It is considered that the improvement of the characteristics of the electrolytic capacitor is achieved by the cyclic organic compound.

  Examples of the organic solvent used for preparing the pretreatment solution, that is, an organic solvent solution in which a cyclic organic compound having at least one hydroxyl group and a high-boiling solvent having a boiling point of 150 ° C. or higher are prepared include, for example, methanol, ethanol , Lower alcohols such as propanol and butanol, and low-boiling organic solvents such as acetonitrile, acetone, tetrahydrofuran, and ethyl acetate.

  The low boiling point means that the boiling point is lower than the boiling point of a high boiling point solvent having a temperature of 150 ° C. or higher, and the drying in the pretreatment step is performed mainly for the purpose of removing the organic solvent as the solvent. Usually, it is performed at a temperature higher than the boiling point of the organic solvent.

  The high-boiling solvent having a boiling point of 150 ° C. or higher in the pretreatment solution is almost removed by azeotropy with the organic solvent at the time of drying, but a part of them has at least one hydroxyl group. It remains in a state of being adsorbed to the cyclic organic compound, and as described above, the remaining part improves the compatibility between the cyclic organic compound having at least one hydroxyl group and the conductive polymer. It is thought that it contributes to the characteristic improvement by the cyclic organic compound which has at least one.

  Regarding the high boiling point solvent, the boiling point is set to 150 ° C. or higher in order to prevent adverse effects on the heat resistance of the electrolytic capacitor even if it remains in the electrolytic capacitor. This is based on the fact that a storage test at 150 ° C. is adopted as one of the tests in the evaluation.

  In the pretreatment solution, the concentration of the cyclic organic compound having at least one hydroxyl group is preferably 0.1 to 50% by mass, more preferably 1% by mass or more within the range, and 10% by mass or less. The concentration of the high-boiling solvent having a boiling point of 150 ° C. or higher is preferably 0.05 to 10% by mass, more preferably 0.2% by mass or more, and more preferably 5% by mass or less. preferable.

  In preparing the pretreatment solution, when a lower alcohol such as methanol or ethanol is used as the organic solvent, in order to increase the solubility of the cyclic organic compound having at least one hydroxyl group, for example, methylamine, dimethyl Lower amine compounds such as amine, trimethylamine, ethylamine, diethylamine, triethylamine, and ethylenediamine, and basic substances such as ammonia, imidazole, methylimidazole, methylethylimidazole, and methylbutylimidazole may be added.

  Furthermore, the voltage resistance of the electrolytic capacitor can be improved by adding 3-glycidoxypropyltrimethoxysilane, polyethylene glycol diglycidyl ether, diethylene glycol glycidyl, glycidyl methacrylate, etc. to the pretreatment solution. Therefore, it is preferable. The addition amount to the solution of the cyclic organic compound having at least one hydroxyl group of the withstand voltage improver composed of 3-glycidoxypropyltrimethoxysilane as described above is added to the cyclic organic compound having at least one hydroxyl group. On the other hand, 0.1 to 1000% by mass (that is, 0.1 to 1000 parts by mass of a withstand voltage improver with respect to 100 parts by mass of the cyclic organic compound having at least one hydroxyl group) is preferable. More preferably, it is more than 300% by mass.

  Next, the capacitor element and the pretreatment for it will be described.

  First, regarding the capacitor element, the one used in the present invention has at least one valve metal porous body selected from the group consisting of aluminum, tantalum, and niobium, and a dielectric layer made of an oxide film of the valve metal. However, the configuration of such a capacitor element specifies a basic configuration common to capacitor elements used in aluminum electrolytic capacitors, tantalum electrolytic capacitors, and niobium electrolytic capacitors. It is not intended and can be applied as a capacitor element in any electrolytic capacitors such as aluminum electrolytic capacitors, tantalum electrolytic capacitors, and niobium electrolytic capacitors. For example, an anode having a dielectric layer made of an oxide film of the valve metal on at least one surface of the porous body of the valve metal, and a cathode may be wound or laminated via a separator to form a capacitor element. After the capacitor element is formed using the one having the porous body of the valve metal and the dielectric layer made of the oxide film of the valve metal as an anode, and after forming a conductive polymer layer serving as a solid electrolyte, and further post-processing Alternatively, a cathode may be formed by sequentially forming a carbon layer and a silver paint layer.

  The capacitor element is pretreated by impregnating the capacitor element with the pretreatment solution and then drying it at least once. The impregnation of the capacitor element with the pretreatment solution is performed by immersing the capacitor element in the pretreatment solution, or spraying or applying the pretreatment solution to the capacitor element. When the impregnation of the pretreatment solution is performed by immersing the capacitor element in the pretreatment solution, the drying after the impregnation is performed after the capacitor element is taken out from the pretreatment solution. By impregnating the capacitor element with the pretreatment solution, the pretreatment solution is not only in the surface of the capacitor element but also in a capacitor element using a porous anode or separator in a state of entering the gap of the separator. Since it is held and then dried, the cyclic organic compound having at least one hydroxyl group contained in the pretreatment solution enters not only the surface of the capacitor element but also the inside of the gap of the anode or separator. Will come to exist. The reason why this treatment step is referred to as pretreatment is that it is carried out before the conductive polymer layer is formed on the capacitor element.

  Next, the conductive polymer dispersion used in the present invention will be described.

  The conductive polymer dispersion used in the present invention is a conductive polymer dispersion obtained by oxidative polymerization of thiophene or a derivative thereof with a polymer anion as a dopant.

  As the polymer anion, polymer sulfonic acid, polymer carboxylic acid or the like is used, and it is composed of styrene sulfonic acid and methacrylic acid ester, acrylic acid ester and unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof. A copolymer with at least one non-sulfonic acid monomer selected from the group can also be used.

  As the polymer sulfonic acid, for example, at least one selected from the group consisting of polystyrene sulfonic acid, sulfonated polyester, and phenolsulfonic acid novolak resin having a repeating unit represented by the following general formula (1) is preferable. Used.

（式中、Ｒ^１は水素またはメチル基である）

(Wherein R ¹ is hydrogen or a methyl group)

  This is because these polymer sulfonic acids function as an excellent dispersant during the synthesis of conductive polymers, and thiophene or its derivatives as oxidants or monomers are uniformly dispersed in water or aqueous liquids. In addition, it is because it is incorporated as a dopant in the polymer to be synthesized, and the obtained conductive polymer is made to have high conductivity suitable for use as a solid electrolyte of an electrolytic capacitor. And, the polymer sulfonic acid functions as an excellent dispersing agent, so that the obtained conductive polymer has excellent heat resistance suitable for use as a solid electrolyte of an electrolytic capacitor. It is done.

  As said polystyrene sulfonic acid, that whose weight average molecular weight is 10,000-1,000,000 is preferable.

  That is, when the weight average molecular weight of the polystyrene sulfonic acid is smaller than 10,000, the conductivity of the obtained conductive polymer may be lowered. Moreover, when the weight average molecular weight of the said polystyrene sulfonic acid is larger than 1,000,000, there exists a possibility that the viscosity of the dispersion liquid of a conductive polymer may become high and it may become difficult to use in preparation of an electrolytic capacitor. The polystyrene sulfonic acid has a weight average molecular weight within the above range, preferably 20,000 or more, more preferably 40,000 or more, and preferably 800,000 or less. More preferable is 1,000 or less.

  The sulfonated polyester is a polycondensation polymer of dicarboxybenzenesulfonic acid diester such as sulfoisophthalic acid ester or sulfoterephthalic acid ester and alkylene glycol in the presence of a catalyst such as antimony oxide or zinc oxide. The sulfonated polyester preferably has a weight average molecular weight of 5,000 to 300,000.

  That is, when the weight average molecular weight of the sulfonated polyester is less than 5,000, the conductivity of the obtained conductive polymer may be lowered. Further, when the weight average molecular weight of the sulfonated polyester is larger than 300,000, the viscosity of the dispersion liquid of the conductive polymer is increased, which may make it difficult to use in the production of the electrolytic capacitor. The sulfonated polyester preferably has a weight average molecular weight within the above range of 10,000 or more, more preferably 20,000 or more, and preferably 100,000 or less. More preferable is 1,000 or less.

  Further, as described above, the phenolsulfonic acid novolak resin has a repeating unit represented by the general formula (1). The phenolsulfonic acid novolak resin has a weight average molecular weight of 5,000. ~ 500,000 are preferred.

  That is, when the weight average molecular weight of the phenolsulfonic acid novolak resin is smaller than 5,000, the conductivity of the obtained conductive polymer may be lowered. Moreover, when the weight average molecular weight of the said phenolsulfonic acid novolak resin is larger than 500,000, there exists a possibility that the viscosity of the dispersion liquid of a conductive polymer may become high, and it may become difficult to use in preparation of an electrolytic capacitor. The phenol sulfonic acid novolak resin preferably has a weight average molecular weight within the above range of 10,000 or more, more preferably 400,000 or less, and more preferably 80,000 or less. preferable.

  The polystyrene sulfonic acid, sulfonated polyester, phenol sulfonic acid novolak resin and the like can be used alone or in combination of two or more. The conductive polymer dispersion used in the present invention may be a conductive polymer dispersion synthesized by mixing these polymer sulfonic acids in the synthesis of the conductive polymer. Alternatively, a conductive polymer may be synthesized using each of the above-described polymer sulfonic acids separately, and the conductive polymer dispersion may be mixed after the synthesis of the conductive polymer.

  A copolymer of the styrene sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of a methacrylic acid ester, an acrylic acid ester, an unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof (hereinafter, A conductive polymer obtained by oxidative polymerization of thiophene or a derivative thereof using a styrene sulfonic acid and a non-sulfonic acid monomer as a dopant) is highly conductive, Moreover, since it has excellent heat resistance, it is suitable for manufacturing an electrolytic capacitor having low ESR, high reliability under high temperature conditions, and low leakage current.

  A copolymer of the styrene sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of a methacrylic acid ester, an acrylic acid ester, an unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof is synthesized. In this case, at least one selected from the group consisting of methacrylic acid esters, acrylic acid esters and unsaturated hydrocarbon-containing alkoxysilane compounds or hydrolysates thereof is used as the monomer to be copolymerized with styrene sulfonic acid. As, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, diphenylbutyl methacrylate, methacryl Dimethylaminoethyl, diethylaminoethyl methacrylate, sodium sulfohexyl methacrylate, glycidyl methacrylate, methyl glycidyl methacrylate, hydroxyalkyl methacrylate, ie hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate , Hydroxyhexyl methacrylate, hydroxy stearyl methacrylate, and other hydroxyalkyl methacrylates, hydroxypolyoxyethylene methacrylate, methoxyhydroxypropyl methacrylate, ethoxyhydroxypropyl methacrylate, dihydroxypropyl methacrylate, dihydroxybutyl methacrylate, etc. , Especially hydroxymethyl methacrylate, methacrylic acid Dorokishiechiru, hydroxypropyl methacrylate, methacrylic acid hydroxyalkyl having a carbon number 1 to 4 alkyl groups, such as methacrylic acid hydroxybutyl are preferable in the characteristics as a dopant when the copolymerised with styrene sulfonic acid. In addition, those having a glycidyl group such as glycidyl methacrylate and methyl glycidyl methacrylate have a structure containing a hydroxyl group by ring opening of the glycidyl group. Like alkyl, it is preferable from the viewpoint of characteristics as a dopant when copolymerized with styrenesulfonic acid.

  Examples of the acrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, stearyl acrylate, cyclohexyl acrylate, diphenylbutyl acrylate, dimethylaminoethyl acrylate, Acrylic acid such as diethylaminoethyl acrylate, sodium sulfohexyl acrylate, glycidyl acrylate, methyl glycidyl acrylate, hydroxyalkyl acrylate, ie hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate Hydroxyalkyl and the like can be used, but hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, The number of carbon atoms in the alkyl group, such as Le hydroxypropyl butyl is 1-4 acrylic acid hydroxyalkyl, preferably from the properties as a dopant when the copolymerised with styrene sulfonic acid. In addition, those having a glycidyl group such as glycidyl acrylate and methyl glycidyl acrylate have a structure containing a hydroxyl group by ring opening of the glycidyl group. Like alkyl, it is preferable from the viewpoint of characteristics as a dopant when copolymerized with styrenesulfonic acid.

  Examples of the unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyldimethylmethoxysilane, 3- Methacryloxypropyldimethylethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxymethyldimethoxysilane, 3-acryloxymethyldiethoxysilane, 3-acryloxytriethoxysilane, p-styryltrimethoxysilane, p-styryltriethoxysilane, p-styrylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxy Run, it can be used an unsaturated hydrocarbon containing alkoxysilane compound and a hydrolyzate thereof such as vinyl dimethyl methoxy silane. For example, when the unsaturated hydrocarbon-containing alkoxysilane compound is the above-mentioned 3-methacryloxypropyltrimethoxysilane, the hydrolyzate of the unsaturated hydrocarbon-containing alkoxysilane compound is converted into a hydroxyl group by hydrolysis of the methoxy group. The resulting structure is 3-methacryloxytrihydroxysilane, or silanes are condensed to form an oligomer, and a compound having a structure in which a methoxy group not used in the reaction is converted into a hydroxyl group is obtained. Examples of the unsaturated hydrocarbon-containing alkoxysilane compound include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, p-styryltrimethoxysilane, vinyltrimethoxysilane, and the like. It is preferable from the standpoint of properties as a dopant when copolymerized.

  Styrene in a copolymer of this styrene sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of methacrylic acid esters, acrylic acid esters and unsaturated hydrocarbon-containing alkoxysilane compounds or hydrolysates thereof As a ratio of sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of methacrylic acid ester, acrylic acid ester and unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof, It is preferably 1: 0.01 to 0.1: 1.

  A copolymer of the styrene sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of a methacrylic acid ester, an acrylic acid ester, an unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof, The molecular weight is preferably about 5,000 to 500,000 in terms of weight average molecular weight from the viewpoint of water solubility and characteristics as a dopant, and more preferably about 40,000 to 200,000 in terms of weight average molecular weight.

  A copolymer of this styrene sulfonic acid and a non-sulfonic acid monomer can also be used in combination with a high molecular sulfonic acid such as polystyrene sulfonic acid, sulfonated polyester, phenol sulfonic acid novolak resin, or the like. Mixing and using a dispersion of a conductive polymer synthesized using a copolymer of a sulfonic acid and a non-sulfonic acid monomer as a dopant and a dispersion of a conductive polymer synthesized using the polymer sulfonic acid as a dopant You can also.

  In preparing the dispersion containing the conductive polymer, thiophene or a derivative thereof is used as a monomer for synthesizing the conductive polymer. Examples of the thiophene derivative include 3,4-ethylenediethylene. Oxythiophene, its 3,4-ethylenedioxythiophene alkyl derivatives, 3-alkylthiophene, 3-alkoxythiophene, 3-alkyl-4-alkoxythiophene, 3,4-alkylthiophene, 3,4-alkoxythiophene, etc. 1 to 16 is suitable for the carbon number of the alkyl group or alkoxy group, and 3,4-ethylenedioxythiophene or an alkyl derivative thereof is particularly preferable.

  The 3,4-ethylenedioxythiophene and alkyl derivatives thereof will be described in detail below. In the following, the “3,4-ethylenedioxythiophene” oxygen atom coordinate position is shown. "Is abbreviated to" ethylenedioxythiophene ".

  The said ethylenedioxythiophene or its alkyl derivative corresponds to the compound represented by following General formula (2).

（式中、Ｒ^２は水素またはアルキル基である）

(Wherein R ² is hydrogen or an alkyl group)

And, the compound in which R ² in the general formula (2) is hydrogen is ethylenedioxythiophene, and this is expressed by IUPAC name, “2,3-dihydro-thieno [3,4-b] [1, 4) Dioxin (2,3-Dihydro-thieno [3,4-b] [1,4] dioxine) ”, but this compound is more commonly named“ ethylenedioxy ”than represented by the IUPAC name. In many cases, “2,3-dihydro-thieno [3,4-b] [1,4] dioxin” is expressed as “ethylenedioxythiophene”. When R ² in the general formula (2) is an alkyl group, as the alkyl group, having a carbon number of 1-4, i.e., a methyl group, an ethyl group, a propyl group, a butyl group are preferred, they Specifically, a compound in which R ² in the general formula (2) is a methyl group is represented by “IUPAC name”, “2-methyl-2,3-dihydro-thieno [3,4-b] [1 , 4] dioxin (2-Methyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxine) ”, but in this document, this is simplified to“ methylated ethylenedioxythiophene ”. Is displayed. A compound in which R ² in the general formula (2) is an ethyl group is represented by “IUPAC name”, “2-ethyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin (2 -Ethyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxine) ", but in this document, this is simplified and displayed as" ethylated ethylenedioxythiophene ".

The compound in which R ² in the general formula (2) is a propyl group is represented by “IUPAC name”, “2-propyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin (2 -Propyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxine) ", but in this document, this is simplified and displayed as" propylated ethylenedioxythiophene ". And the compound in which R ² in the general formula (2) is a butyl group is represented by “IUPAC name”, “2-butyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin”. (2-Butyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxine) ”, but in this document, this is simplified and expressed as“ butylated ethylenedioxythiophene ”. . In addition, “2-alkyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin” is simply expressed as “alkylated ethylenedioxythiophene” in this document. Among these alkylated ethylenedioxythiophenes, methylated ethylenedioxythiophene, ethylated ethylenedioxythiophene, propylated ethylenedioxythiophene, and butylated ethylenedioxythiophene are preferred, and in particular ethylated ethylenedioxythiophene. Propylated ethylenedioxythiophene is preferred. The method for synthesizing these alkylated ethylenedioxythiophenes is specifically disclosed in International Publication Nos. 2011/0608026 and 2011/074380 filed by the present applicant.

  These ethylenedioxythiophenes and alkyl derivatives thereof (that is, alkylated ethylenedioxythiophenes) can be used alone or in combination of two or more.

  Next, a means for oxidative polymerization of thiophene or a derivative thereof with a polymer anion as a dopant to synthesize a conductive polymer will be described. Polymer sulfonic acids such as polystyrene sulfonate, sulfonated polyester, phenol sulfonate novolak resin, , A copolymer of a styrene sulfonic acid and a non-sulfonic acid monomer (that is, selected from the group consisting of styrene sulfonic acid, methacrylic acid ester, acrylic acid ester, unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof) Copolymers of at least one kind of non-sulfonic acid monomer) are soluble in an aqueous liquid composed of water or a mixture of water and a water-miscible solvent. The polymerization is performed in water or an aqueous liquid.

  Examples of the water-miscible solvent constituting the aqueous liquid include methanol, ethanol, propanol, acetone, acetonitrile, and the like. The mixing ratio of these water-miscible solvents with water is 50 in the entire aqueous liquid. The mass% or less is preferable.

  As the oxidative polymerization for synthesizing the conductive polymer, either chemical oxidative polymerization or electrolytic oxidative polymerization can be employed.

  For example, persulfate is used as an oxidizing agent in performing chemical oxidative polymerization. Examples of the persulfate include ammonium persulfate, sodium persulfate, potassium persulfate, calcium persulfate, and barium persulfate. Is used.

  In chemical oxidative polymerization, the conditions during the polymerization are not particularly limited, but the temperature during chemical oxidative polymerization is preferably 5 ° C to 95 ° C, more preferably 10 ° C to 30 ° C, and polymerization is also performed. As time, 1 hour-72 hours are preferable, and 8 hours-24 hours are more preferable.

Electrolytic oxidation polymerization is be carried out even at a constant voltage at a constant current, for example, when performing electrolytic oxidation polymerization at a constant current, preferably 0.05mA ^/ cm ² ~10mA ^/ cm 2 as the current value, 0.2 mA / cm more preferably ^{2 ~4mA} / cm ^2, when performing electrolytic oxidation polymerization at a constant voltage, preferably 0.5V~10V as voltage, 1.5V to 5V is more preferable. The temperature during electrolytic oxidation polymerization is preferably 5 ° C to 95 ° C, and particularly preferably 10 ° C to 30 ° C. The polymerization time is preferably 1 hour to 72 hours, more preferably 8 hours to 24 hours. In the electrolytic oxidation polymerization, ferrous sulfate or ferric sulfate may be added as a catalyst.

  The conductive polymer obtained as described above is obtained immediately after polymerization in a state of being dispersed in water or an aqueous liquid, and includes persulfate as an oxidizing agent, iron sulfate used as a catalyst, and decomposition products thereof. Contains. Therefore, the conductive polymer dispersion containing the impurities is dispersed in a dispersing machine such as an ultrasonic homogenizer or a planetary ball mill, and then the metal component is removed with a cation exchange resin. The particle size of the conductive polymer measured by the dynamic light scattering method at this time is preferably 100 μm or less, more preferably 10 μm or less, preferably 1 nm or more, and more preferably 10 nm or more. Thereafter, the sulfuric acid generated by the decomposition of the oxidizing agent or the catalyst may be removed by an ethanol precipitation method, an ultrafiltration method, an anion exchange resin, or the like, and a high boiling point solvent may be added as necessary.

  As described above, when a high-boiling solvent is contained in the dispersion of the conductive polymer, the film-forming property is improved when the conductive polymer is obtained by drying, thereby improving the conductivity. When improved and used as a solid electrolyte of an electrolytic capacitor, ESR can be reduced. This is because, for example, in the production of an electrolytic capacitor, when the capacitor element is immersed in a dispersion of a conductive polymer, taken out and dried, the high boiling point solvent also escapes, but the high boiling point solvent is removed. When exiting, increase the layer density in the thickness direction of the layer of the conductive polymer formed, thereby reducing the spacing between the conductive polymers, increasing the conductivity of the conductive polymer, When used as a solid electrolyte of an electrolytic capacitor, it is considered that the ESR can be reduced.

  As the high boiling point solvent, those having a boiling point of 150 ° C. or higher are preferable, and specific examples of such a high boiling point solvent may be the same as those exemplified in relation to the pretreatment solution. it can. And as content of this high boiling point solvent, 5-3,000 mass% (namely, high boiling point solvent is 5-3 with respect to 100 mass parts of conductive polymers in dispersion liquid). 000 parts by mass), preferably 20% by mass or more, and more preferably 700% by mass or less within the above range.

  In addition, a binder resin may be added to the dispersion containing the conductive polymer in order to improve the adhesion between the capacitor element and the conductive polymer.

  Examples of such binder resins include polyurethane, polyester, acrylic resin, polyamide, polyimide, epoxy resin, polyacrylonitrile resin, polymethacrylonitrile resin, polystyrene resin, novolac resin, silane coupling agent, etc. Polyester, polyurethane, acrylic resin and the like are preferable. Moreover, since the electroconductivity of a conductive polymer can be improved when the sulfone group is added like sulfonated polyallyl, sulfonated polyvinyl, and sulfonated polystyrene, it is more preferable.

  As described above, the conductive polymer dispersion used in the present invention may contain a high boiling point solvent or a binder resin, and may contain them, but in the present invention, essential components are included. As long as the conductive polymer is contained, it is called a conductive polymer dispersion regardless of whether or not it contains the above high-boiling solvent or binder.

  In the present invention, in the production of the electrolytic capacitor, as described above, after impregnating the capacitor element with the pretreatment solution, the capacitor element after the pretreatment is pretreated by performing an operation of drying at least once. After impregnating a dispersion of a conductive polymer having an anion as a dopant, a drying operation is performed at least once to form a conductive polymer layer that will form a solid electrolyte in the capacitor element after pretreatment. To do.

  The above “at least once” may mean one time or more times, that is, two times or more. Usually, the pretreatment with the pretreatment solution for the capacitor element is performed. In many cases, the capacitor element is impregnated with the pretreatment solution and then dried only once. However, after the pretreatment capacitor element is impregnated with the conductive polymer dispersion, the operation of drying is performed. Repeating 2 to 3 times is suitable for obtaining a desired capacity when a capacitor is used.

  As described above, the pre-treated capacitor element is impregnated with a dispersion of a conductive polymer having a polymer anion as a dopant, and then dried to form a conductive polymer layer on the pre-treated capacitor element. The operation may be referred to as “main treatment”. The impregnation of the pre-treated capacitor element with the dispersion of the conductive polymer in this main treatment may be performed after the pre-treatment of the capacitor element with the conductive polymer dispersion liquid. Or by spraying or applying a dispersion of a conductive polymer to the capacitor element after the pretreatment. When the impregnation is performed by immersing the pretreated capacitor element in the conductive polymer dispersion, drying is performed after taking out the pretreated capacitor element from the conductive polymer dispersion. Do.

  In the main treatment as described above, the dispersion of the conductive polymer using the polymer anion as a dopant is preferably at 25 ° C. and pH 2-4. This is because when the pH of the conductive polymer dispersion at 25 ° C. is lower than 2, there is a risk of destroying the oxide film of the capacitor element. This is because if it exceeds 4, the ESR of the capacitor may be deteriorated (that is, high).

  In the present invention, a capacitor element in which a conductive polymer layer is formed through the main treatment using a dispersion of a conductive polymer having a polymer anion as a dopant as described above, has a cyclic structure having at least one hydroxyl group. After impregnating the organic solvent solution in which the organic compound is dissolved, the electrolytic capacitor is manufactured through at least one drying operation, or at least one hydroxyl group is added to the capacitor element in which the conductive polymer layer is formed. An electrolytic capacitor is manufactured through at least one impregnation with a solution obtained by dissolving a cyclic organic compound having a high boiling point solvent having a boiling point of 150 ° C. or higher. In the present invention, this treatment step is referred to as post-treatment because this treatment is performed after the conductive polymer layer is formed on the capacitor element.

  The solution used for the post-treatment is referred to as a post-treatment solution, and the capacitor element after the formation of the conductive polymer layer is post-treated with the specific post-treatment solution as described above. The capacitance can be increased and the withstand voltage can be further increased.

  The impregnation of the post-treatment solution into the capacitor element in which the conductive polymer layer is formed in the post-treatment is performed by immersing the capacitor element in the post-treatment solution, or spraying the post-treatment solution on the capacitor element, This is done by applying.

  When an organic solvent solution in which a cyclic organic compound having at least one hydroxyl group is dissolved is used as the post-treatment solution, the post-treatment solution is impregnated and dried. In the case where it is performed by immersing it in a working solution, drying is performed after the capacitor element is taken out of the post-treatment solution. Further, when a solution in which a cyclic organic compound having at least one hydroxyl group is dissolved in a high-boiling organic solvent having a boiling point of 150 ° C. or higher is used as a post-treatment solution, it is not dried after the impregnation. The working solution will remain in the electrolytic capacitor.

  The organic solvent solution in which the cyclic organic compound having at least one hydroxyl group used as the post-treatment solution in the post-treatment after forming the conductive polymer layer as described above has at least one hydroxyl group. The cyclic organic compound can be the same as that used in the preparation of the pretreatment solution, and the organic solvent can be the same organic solvent used in the preparation of the pretreatment solution. it can.

  The organic solvent solution in which the cyclic organic compound having at least one hydroxyl group is dissolved is a post-treatment solution that is dried at the time of post-treatment. In the case where the cyclic organic compound having at least one of the above is difficult to dissolve in a lower alcohol such as methanol or ethanol, for example, lower amine compounds such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, ammonia, imidazole Basic substances such as methylimidazole, methylethylimidazole, and methylbutylimidazole may be added to facilitate dissolution of the cyclic organic compound having at least one hydroxyl group in the organic solvent as described above.

  The concentration of the cyclic organic compound having at least one hydroxyl group in the solution is not particularly limited, but is preferably 0.1 to 80% by mass, and more preferably 1% by mass or more within the above range. Moreover, 10 mass% or less is more preferable.

  When the concentration of the cyclic organic compound having at least one hydroxyl group in the solution is in the range of 0.1 to 80% by mass as described above, a conductive polymer layer (hereinafter simply referred to as “conductive polymer”). It is not necessary to increase the number of immersions in the solution of the cyclic organic compound having at least one hydroxyl group of the capacitor element in which the capacitor element formed) is formed, and also the workability is deteriorated due to the excessively high viscosity. It becomes difficult.

  The liquid property of the solution of the cyclic organic compound having at least one hydroxyl group is not particularly limited, but the pH is preferably in the range of 1 to 11. This is because when the pH is higher than 11, the conductive polymer may be undoped by alkali, and when the pH is lower than 1, the oxide film of the capacitor element may be damaged to increase the leakage current. Because.

  When a capacitor element having a conductive polymer layer is impregnated with a solution of a cyclic organic compound having at least one hydroxyl group and dried, the cyclic organic compound having at least one hydroxyl group is mostly conductive. Although it exists in the form of a thin film on the polymer layer, when it is in a solution state, a part of it penetrates into the conductive polymer layer and is dried in that state, so that the cyclic organic having at least one hydroxyl group It is considered that a part of the compound has entered the inside of the conductive polymer layer.

  The amount of the cyclic organic compound having at least one hydroxyl group is 1 to 5,000% by mass with respect to the conductive polymer (the cyclic organic compound having at least one hydroxyl group with respect to 100 parts by mass of the conductive polymer). Is preferably 1 to 5,000 parts by mass, more preferably 20% by mass or more, and even more preferably 500% by mass or less within the above range.

  It is preferable to add a high boiling point solvent to the solution of the cyclic organic compound having at least one hydroxyl group. This is because when a high boiling point solvent is contained in a solution in which a cyclic organic compound having at least one hydroxyl group is dissolved, the film-forming property of the cyclic organic compound having at least one hydroxyl group is improved. This is because the voltage resistance can be further lowered and the withstand voltage can be further increased.

  As such a high boiling point solvent, those having a boiling point of 150 ° C. or higher are preferable, and specific examples of such a high boiling point solvent may be the same as those exemplified for the pretreatment solution. it can. The amount of the high-boiling solvent added is 5 to 5,000% by mass (that is, 100 parts by mass of the cyclic organic compound having at least one hydroxyl group) with respect to the cyclic organic compound having at least one hydroxyl group. On the other hand, the high boiling point solvent is preferably 5 to 5,000 parts by mass).

  Examples of the high-boiling solvent having a boiling point of 150 ° C. or higher as described above include ethylene glycol (boiling point: 198 ° C.), N-methylpyrrolidone (boiling point: 202 ° C.), γ-butyrolactone (boiling point: 203 ° C.), dimethyl sulfoxide ( (Boiling point: 189 ° C.), etc., when the boiling point is in the range of 150 ° C. to 210 ° C., the added amount of the high boiling point solvent in the range of 150 ° C. to 210 ° C. is at least one hydroxyl group. 200 mass% or more is more preferable within the preferable range of 5-5,000 mass% with respect to the cyclic organic compound to have.

  Examples of the high-boiling solvent having a boiling point of 150 ° C. or higher as described above include, for example, butanediol (boiling point: 230 ° C.) diethylene glycol (boiling point: 244 ° C.), glycerol (that is, glycerin) (boiling point: 290 ° C.), diglycerol (That is, diglycerin) [boiling point: 265 ° C. (15 mmHg)], when a high boiling point solvent having a boiling point higher than 210 ° C. such as polyethylene glycol is used, Within a preferable range of 5 to 5,000% by mass with respect to the cyclic organic compound having at least one group, 20% by mass or more is more preferable, and 700% by mass or less is more preferable.

  When the amount of the high-boiling solvent added is less than the above, when the capacitor element after the formation of the conductive polymer layer is impregnated with the organic solvent solution of the cyclic organic compound having at least one hydroxyl group, one of the conductive polymers is added. When the part dissolves or swells and it dries, the conformation (structure) changes and the conductivity of the conductive polymer decreases, resulting in an increase in ESR of the electrolytic capacitor and a higher withstand voltage. The action may be reduced. If the amount of the high-boiling solvent added is larger than the above, it takes time to dry the solution, and the ESR may be increased due to the thermal history.

  Further, by adding 3-glycidoxypropyltrimethoxysilane, polyethylene glycol diglycidyl ether, diethylene glycol glycidyl, glycidyl methacrylate, etc. to the solution of the cyclic organic compound having at least one hydroxyl group, Since the effect | action which improves a withstand voltage increases, it is preferable.

  The amount of cyclic organic compound having at least one hydroxyl group of a voltage resistance improver such as 3-glycidoxypropyltrimethoxysilane, polyethylene glycol glycidyl ether, diethylene glycol glycidyl, and glycidyl methacrylate is added to the hydroxyl group. 0.1 to 1000% by mass with respect to the cyclic organic compound having at least one (ie, binder of 0.1 to 1000 parts by mass with respect to 100 parts by mass of the cyclic organic compound having at least one hydroxyl group) is preferable. Within the above range, 10% by mass or more is more preferable, and 300% by mass or less is more preferable.

  The post-treatment with a post-treatment solution that is dried during the post-treatment is performed by impregnating the capacitor element after the formation of the conductive polymer layer with the post-treatment solution and then drying it at least once. Is called. The impregnation of the capacitor element with the post-treatment solution is performed by immersing the capacitor element in the post-treatment solution, or spraying or applying the post-treatment solution to the capacitor element. Then, when the drying after the impregnation with the post-treatment solution is performed by immersing the capacitor element in the post-treatment solution, the capacitor element is taken out from the post-treatment solution. Do.

  The drying is usually performed at a temperature higher than the boiling point of the organic solvent used as the solvent from the viewpoint of reducing the influence on the conductive polymer by heating and performing post-treatment with good workability.

  Next, a post-treatment solution that does not dry during post-treatment will be described. The post-treatment solution is obtained by dissolving a cyclic organic compound having at least one hydroxyl group as described above in a high boiling point solvent having a boiling point of 150 ° C. or higher.

  The cyclic organic compound having at least one hydroxyl group and the high boiling point solvent having a boiling point of 150 ° C. or higher used in the post-treatment solution that does not dry at the time of this post-treatment are the same as those described above. be able to. And as for the cyclic organic compound having at least one hydroxyl group, the role (action) is the same as in the case explained so far, lowering the ESR, increasing the capacitance, and improving the voltage resistance. The high boiling point solvent having a boiling point of 150 ° C. or higher serves as a solvent for dissolving the cyclic organic compound having at least one hydroxyl group, and keeps the heat resistance of the electrolytic capacitor high. Is for.

  In the post-treatment solution that does not dry during the post-treatment, a high-boiling solvent having a boiling point of 150 ° C. or higher serves as a solvent, and a cyclic organic compound having at least one hydroxyl group serves as a solute. As a density | concentration in the solution of the cyclic organic compound which has 1 or more, 0.5-50 mass% is preferable, 2 mass% or more is more preferable in that range, 5 mass% or more is further more preferable, and 30 mass % Or less is more preferable, and 20% by mass or less is more preferable. That is, when the concentration of the cyclic organic compound having at least one hydroxyl group is lower than the above, the ESR of the electrolytic capacitor may not be sufficiently lowered, and the heat resistance may be lowered, and at least one hydroxyl group may be present. When the concentration of the cyclic organic compound is higher than the above, precipitation of the cyclic organic compound is likely to occur, and in addition to poor handleability, ESR of the electrolytic capacitor may be deteriorated.

  When the post-treatment solution contains at least one withstand voltage improver selected from the group consisting of an epoxy compound or a hydrolyzate thereof, a silane compound or a hydrolyzate thereof and a polyalcohol, This is preferable because the effect of improving the voltage resistance is increased.

  The concentration of the withstand voltage improver in the post-treatment solution is preferably 0.05 to 20% by mass, more preferably 0.1% by mass or more, and more preferably 5% by mass or less.

  Examples of the epoxy compound or a hydrolyzate thereof include polyethylene glycol diglycidyl ether, diethylene glycol glycidyl, glycidyl methacrylate, epoxy propanol (that is, glycidol), methyl glycidyl ether, ethyl glycidyl ether, propyl glycidyl ether, and butyl glycidyl. Ether, epoxybutane (ie glycidylmethane), epoxypentane (ie glycidylethane), epoxyhexane (ie glycidylpropane), epoxyheptane (ie glycidylbutane), epoxyoctane (ie glycidylpentane), epoxycyclohexene, Ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, butylene glycol Diglycidyl ether, pentylene glycol diglycidyl ether, hexylene glycol diglycidyl ether, glycerol diglycidyl ether and the like. Examples of the silane compound or a hydrolyzate thereof include 3-aminopropyltrimethoxysilane, n- Phenyl-3-aminopropyltrimethoxysilane, n-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltri Methoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3- Examples thereof include acryloxypropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-isocyanatopropyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, and silica sol. Examples of the polyalcohol include polyethylene glycol, polypropylene glycol, Examples include polybutylene glycol.

  The post-treatment with a post-treatment solution that does not dry during this post-treatment is performed by impregnating the capacitor element with the conductive polymer layer impregnated with the post-treatment solution at least once as described above. Is called. This impregnation is performed by immersing the capacitor element after forming the conductive polymer in a post-treatment solution, or spraying or applying the post-treatment solution to the capacitor element, as described above.

  The post-treatment solution that does not dry at the time of the post-treatment can be used as an electrolytic solution as it is, and therefore does not require drying. Therefore, the post-treatment with the post-treatment solution that does not dry during the post-treatment has the advantage that the drying step can be omitted compared to the post-treatment with the post-treatment solution that is dried during the post-treatment as described above. There is.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited only to those illustrated in these examples. In the following examples and the like,% in the case of indicating the concentration and the amount used is% based on mass unless otherwise specified.

  Prior to the examples, preparation examples of pretreatment solutions used in the examples for pretreatment of capacitor elements are shown in Preparation Examples 1 to 12, and preparation examples of pretreatment solutions used in Comparative Examples are shown in Preparation Examples 13 to 13. 14. An example of preparing a conductive polymer dispersion used for forming a conductive polymer layer on a capacitor element is shown in Preparation Examples (I) to (II), and after forming the conductive polymer layer. Examples of preparation of post-treatment solutions used in post-treatment are shown in Preparation Examples A to B.

Preparation Example 1
After adding 15 g of hydroxybenzenecarboxylic acid butyl ester and 5 g of 3-glycidoxypropyltrimethoxysilane to 500 g of ethanol placed in a 1 L beaker with a stirrer, 5 g of polyethylene glycol 400 is added, and then for 24 hours. A pretreatment solution 1 was prepared by stirring.

  The hydroxybenzene carboxylic acid butyl ester corresponds to a cyclic organic compound having at least one hydroxyl group, and the concentration of the hydroxy benzene carboxylic acid butyl ester in the pretreatment solution 1 is about 2.86%. Corresponds to a high boiling point solvent having a boiling point of 150 ° C. or higher, and the concentration of the polyethylene glycol 400 in the pretreatment solution 1 is about 0.95%. And 3-glycidoxypropyl trimethoxysilane corresponds to a withstand voltage improver, and the concentration of the 3-glycidoxypropyltrimethoxysilane in the pretreatment solution 1 is 0.95%.

Preparation Example 2
After adding 15 g of hydroxybenzenecarboxylic acid and 5 g of 3-glycidoxypropyltrimethoxysilane to 500 g of ethanol in a 1 L beaker with a stirrer, add 5 g of polyethylene glycol 400, and then stir for 24 hours. Thus, a pretreatment solution 2 was prepared.

  The hydroxybenzenecarboxylic acid corresponds to a cyclic organic compound having at least one hydroxyl group, and the concentration of the hydroxybenzenecarboxylic acid in the pretreatment solution 2 is about 2.86%. Others are the same as in the case of the pretreatment solution 1.

Preparation Example 3
A pretreatment solution 3 was prepared in the same manner as in Preparation Example 1, except that 3-glycidoxypropyltrimethoxysilane was not added.

  In this pretreatment solution 3, the concentration of the hydroxybenzene carboxylic acid butyl ester was about 2.88% due to the absence of the withstand voltage improver 3-glycidoxypropyltrimethoxysilane. The concentration of glycol 400 was about 0.96%.

Preparation Example 4
A pretreatment solution 4 was prepared in the same manner as in Preparation Example 2, except that 3-glycidoxypropyltrimethoxysilane was not added.

  In this pretreatment solution 4, the concentration of hydroxybenzene carboxylic acid was about 2.88% due to the absence of addition of the withstand voltage improver 3-glycidoxypropyltrimethoxysilane, and polyethylene glycol 400 Concentration of about 0.96%.

Preparation Example 5
A pretreatment solution 5 was prepared in the same manner as in Preparation Example 1 except that nitrophenol was added instead of hydroxybenzenecarboxylic acid.

  The nitrophenol corresponds to a cyclic organic compound having at least one hydroxyl group, and the concentration of the nitrophenol in the pretreatment solution 5 is about 2.86%. Others are the same as in the case of the pretreatment solution 1.

Preparation Example 6
A pretreatment solution 6 was prepared in the same manner as in Preparation Example 1 except that hydroxynitrobenzenecarboxylic acid was added instead of hydroxybenzenecarboxylic acid butyl ester.

  The hydroxynitrobenzenecarboxylic acid corresponds to a cyclic organic compound having at least one hydroxyl group, and the concentration of the hydroxynitrobenzenecarboxylic acid in the pretreatment solution 6 is about 2.86%. Others are the same as in the case of the pretreatment solution 1.

Preparation Example 7
A pretreatment solution 7 was prepared in the same manner as in Preparation Example 1 except that methoxyphenol was added instead of hydroxybenzenecarboxylic acid butyl ester.

  The methoxyphenol corresponds to a cyclic organic compound having at least one hydroxyl group, and the concentration of the methoxyphenol in the pretreatment solution 7 is about 2.86%. Others are the same as in the case of the pretreatment solution 1.

Preparation Example 8
A pretreatment solution 8 was prepared in the same manner as in Preparation Example 1, except that hydroxynitrobenzenecarboxylic acid butyl ester was added instead of hydroxybenzenecarboxylic acid butyl ester.

  The hydroxynitrobenzenecarboxylic acid butyl ester corresponds to a cyclic organic compound having at least one hydroxyl group, and the concentration of the hydroxynitrobenzenecarboxylic acid butyl ester in the pretreatment solution 8 is about 2.86%. Others are the same as in the case of the pretreatment solution 1.

Preparation Example 9
A pretreatment solution 9 was prepared in the same manner as in Preparation Example 1, except that diglycerol was added instead of polyethylene glycol 400.

  The diglycerol corresponds to a high boiling point solvent having a boiling point of 265 ° C. (15 mmHg) and a boiling point of 150 ° C. or higher, and the concentration of the diglycerol in the pretreatment solution 9 is about 0.95%. Others are the same as in the case of the pretreatment solution 1.

Preparation Example 10
A pretreatment solution 10 was prepared in the same manner as in Preparation Example 2, except that diglycerol was added instead of polyethylene glycol 400.

The concentration of the diglycerol in the pretreatment solution 10 is about 0.95%. Others are the same as in the case of the pretreatment solution 2.
Preparation Example 11
A pretreatment solution 11 was prepared in the same manner as in Preparation Example 1 except that polyethylene glycol diglycidyl ether was added instead of 3-glycidoxypropyltrimethoxysilane.

  The polyethylene glycol diglycidyl ether corresponds to a withstand voltage improver, and the concentration of the polyethylene glycol diglycidyl ether pretreatment solution 11 is 0.95%. Others are the same as in the case of the pretreatment solution 1.

Preparation Example 12
A pretreatment solution 7 was prepared in the same manner as in Preparation Example 2, except that polyethylene glycol diglycidyl ether was added instead of 3-glycidoxypropyltrimethoxysilane.

  The concentration of the polyethylene glycol diglycidyl ether in the pretreatment solution 12 is about 0.95%. Others are the same as in the case of the pretreatment solution 2.

Preparation Example 13 (for comparative example)
A pretreatment solution 13 for a comparative example was prepared in the same manner as in Preparation Example 1 except that hydroxybenzenecarboxylic acid butyl ester was not added.

Preparation Example 14 (for comparative example)
A pretreatment solution 14 for a comparative example was prepared in the same manner as in Preparation Example 1, except that toluenesulfonic acid was added instead of hydroxybenzenecarboxylic acid butyl ester.

Preparation Example of Conductive Polymer Dispersion (I)
600 g of 3% aqueous solution of polystyrene sulfonic acid (weight average molecular weight 100,000) manufactured by Teika Co., Ltd. was put into a stainless steel container having an internal volume of 1 L, and 0.3 g of ferrous sulfate heptahydrate was added. 4 mL of 3,4-ethylenedioxythiophene was slowly added dropwise.

They were stirred with a stainless steel stirring blade, an anode was attached to the container, a cathode was attached to the base of the stirring blade, and electrolytic oxidation polymerization was performed at a constant current of 1 mA / cm ² for 18 hours. After the electrolytic oxidation polymerization, the mixture was diluted 6 times with water, and then subjected to a dispersion treatment for 2 hours with an ultrasonic homogenizer [Nippon Seiki Co., Ltd., US-T300 (trade name)]. Thereafter, 100 g of Cation Exchange Resin Amberlite 120B (trade name) manufactured by Organo Corporation was added and stirred with a stirrer for 1 hour. Subsequently, filter paper No. manufactured by Toyo Filter Paper Co., Ltd. The mixture was filtered through 131, and the treatment with this cation exchange resin and filtration were repeated three times to remove all cation components such as iron ions in the liquid.

  The treated liquid is passed through a filter having a pore size of 1 μm, and the passing liquid is treated with an ultrafiltration apparatus (Vivaflow 200 (trade name), molecular weight fraction 50,000, manufactured by Sartorius Co., Ltd.). Ingredients were removed. The liquid after this treatment was diluted with water to adjust the concentration to 2%, and then the pH was adjusted to 3.2 with a 28% aqueous ammonia solution to obtain a conductive polymer dispersion (I).

  When the particle size distribution of the conductive polymer in the obtained dispersion liquid (I) of the conductive polymer was measured by ELS-Z manufactured by Otsuka Electronics, the average particle size was 150 nm.

Preparation Example of Conductive Polymer Dispersion (II)
1 L of pure water was added to a 2 L separable flask equipped with a stirrer, and 170 g of sodium styrenesulfonate (152 g as styrenesulfonic acid) and 30 g of hydroxyethyl acrylate were added thereto. And 1g of ammonium persulfate was added to the solution as an oxidizing agent, and the polymerization reaction of styrenesulfonic acid and hydroxyethyl acrylate was performed for 12 hours.

  Then, the reaction solution is treated with an ultrafiltration device (Vivaflow 200 (trade name) manufactured by Sartorius Co., Ltd., molecular weight fraction 50,000) to remove free low-molecular components in the solution to a concentration of 3%. By adjusting, a 3% aqueous solution of a copolymer of styrene sulfonic acid and hydroxyethyl acrylate was obtained.

  The obtained styrene sulfonic acid and hydroxyethyl acrylate copolymer had a weight average molecular weight of 150,000 estimated using a gel filtration column and dextran as a standard.

  Then, instead of the polystyrene sulfonic acid aqueous solution having a concentration of 3% in the dispersion liquid (I) of the conductive polymer, a 3% aqueous solution of the copolymer of styrene sulfonic acid and hydroxyethyl acrylate was used, All the same operations as in Preparation Example (I) were performed to obtain a conductive polymer dispersion having a concentration of 2%. A 28% aqueous ammonia solution was added to the 2% conductive polymer dispersion to adjust the pH to 2.7. Then, 3 g of dimethyl sulfoxide (about 375% with respect to the conductive polymer) was added to 40 g of the solution to obtain a conductive polymer dispersion (II).

  When the particle size distribution of the conductive polymer in the dispersion liquid (II) of this conductive polymer was measured by ELS-Z manufactured by Otsuka Electronics, the average particle size was 130 nm.

Example A of preparation of post-treatment solution
Hydroxybenzene carboxylic acid was dissolved in a mixed solvent having a mass ratio of ethanol and ethylene glycol of 1: 1 to prepare a 2% concentration solution. Then, 2 g of nitrophenol was added to 100 g of the 2% ethanol-ethylene glycol solution of hydroxybenzene carboxylic acid, and 1 g of polyethylene glycol diglycidyl was further added and stirred to obtain a post-treatment solution A. The pH of the post-treatment solution A was 3.9.

  The hydroxybenzene carboxylic acid corresponds to a cyclic organic compound having at least one hydroxyl group, the concentration of the hydroxybenzene carboxylic acid in the post-treatment solution A is about 1.93%, and the nitrophenol also has a hydroxyl group. This corresponds to a cyclic organic compound having at least one, and the concentration of the nitrophenol in the aftertreatment solution A is also about 1.93%. The polyethylene glycol diglycidyl corresponds to a withstand voltage improver, the concentration in the polyethylene glycol diglycidyl post-treatment solution is about 0.97%, and the ethylene glycol has a boiling point of 179 ° C. This corresponds to a high-boiling solvent having a boiling point of 150 ° C. or higher, and the concentration in the ethylene glycol aftertreatment solution is about 48%. This post-treatment solution A is used for post-treatment after the formation of the conductive polymer layer in Examples 1 to 24 described later, and is a type in which the solvent is dried during the subsequent treatment.

Preparation B for post-treatment solution
After adding 40 g of p-hydroxybenzenecarboxylic acid, 5 g of nitrophenol and 4 g of polyethylene glycol diglycidyl ether to 500 g of γ-butyrolactone placed in a 1 L beaker equipped with a stirrer, 8 g of dimethylamine was added and stirred for 24 hours. As a result, a post-treatment solution B was obtained.

  The γ-butyrolactone corresponds to a high-boiling solvent having a boiling point of 203 ° C. and a boiling point of 150 ° C. or more, and hydroxybenzenecarboxylic acid and nitrophenol correspond to a cyclic organic compound having at least one hydroxyl group. The concentration in the post-treatment solution B of the cyclic organic compound having at least one is about 8.08%, and the ratio of hydroxybenzenecarboxylic acid to nitrophenol is 8: 1 by mass. The polyethylene glycol diglycidyl corresponds to a withstand voltage improver, the concentration in the polyethylene glycol diglycidyl post-treatment solution is about 0.72%, and the dimethylamine corresponds to an electrolyte cation. The concentration in the dimethylamine aftertreatment solution is about 1.44%. This post-treatment solution B is used for post-treatment after formation of the conductive polymer layer in Examples 25 to 48 described later, and is a type in which the solvent is not dried during the subsequent treatment.

[Evaluation with a wound aluminum electrolytic capacitor (1)]
In the evaluation (1) using the wound aluminum electrolytic capacitor, a wound aluminum electrolytic capacitor of a type in which the solvent is dried during post-processing is manufactured, and the present invention is evaluated with the wound aluminum electrolytic capacitor.

Example 1
After etching the surface of the aluminum foil, a lead terminal is attached to the anode on which the dielectric layer is formed by chemical conversion treatment at 200 V, and the lead terminal is attached to the cathode made of aluminum foil. The cathode was wound through a separator to produce a capacitor element.

  The capacitor element was immersed in the pretreatment solution 1 prepared in Preparation Example 1, and taken out after 1 minute, and dried at 150 ° C. for 15 minutes for pretreatment.

  Next, the capacitor element after the above pretreatment is immersed in the conductive polymer dispersion (I) prepared in Preparation Example (I), taken out after 5 minutes, and dried at 150 ° C. for 30 minutes three times. Thus, a conductive polymer layer serving as a solid electrolyte was formed on the capacitor element.

  And the capacitor | condenser element after forming the said conductive polymer layer is immersed in the post-treatment solution A prepared in the preparation example A of the post-treatment solution, taken out after 1 minute, and dried at 150 ° C. for 15 minutes. After the post-treatment, the wound aluminum electrolytic capacitor of Example 1 was manufactured by packaging with an exterior material.

Examples 2-12
The same procedures as in Example 1 were performed except that the pretreatment solutions 2 to 12 were used in place of the pretreatment solution 1 and the respective pretreatments were performed separately. Type aluminum electrolytic capacitors were manufactured.

Examples 13-24
Except for using the conductive polymer dispersion (II) instead of the conductive polymer dispersion (I), the same operations as in Examples 1 to 12 were carried out. A wound aluminum electrolytic capacitor was manufactured.

Comparative Example 1
A wound aluminum electrolytic capacitor of Comparative Example 1 was produced in the same manner as in Example 1 except that the pretreatment with the pretreatment solution 1 was not performed.

Comparative Example 2
The same procedure as in Example 1 was carried out except that the pretreatment solution 13 for the comparative example was used in place of the pretreatment solution 1, and the wound aluminum electrolysis of the comparative example 2 was performed. A capacitor was manufactured.

Comparative Example 3
The same procedure as in Example 1 was performed except that the pretreatment solution 14 for the comparative example was used in place of the pretreatment solution 1, and the wound aluminum electrolysis of the comparative example 3 was performed. A capacitor was manufactured.

Comparative Example 4
A wound aluminum electrolytic capacitor of Comparative Example 4 was produced in the same manner as in Example 1 except that no post-treatment with the post-treatment solution A was performed.

Comparative Example 5
A wound aluminum electrolytic capacitor of Comparative Example 5 was manufactured in the same manner as in Example 13 except that the pretreatment with the pretreatment solution 1 was not performed.

Comparative Example 6
The same procedure as in Example 13 was performed except that the pretreatment solution 13 for the comparative example was used in place of the pretreatment solution 1, and the wound aluminum electrolysis of the comparative example 6 was performed. A capacitor was manufactured.

Comparative Example 7
The same procedure as in Example 13 was performed except that the pretreatment solution 14 for the comparative example was used in place of the pretreatment solution 1, and the wound aluminum electrolysis of the comparative example 7 was performed. A capacitor was manufactured.

Comparative Example 8
A wound aluminum electrolytic capacitor of Comparative Example 8 was produced in the same manner as in Example 13 except that the post-treatment with the post-treatment solution A was not performed.

  About the wound type aluminum electrolytic capacitors of Examples 1 to 24 and Comparative Examples 1 to 8 manufactured as described above, the kind of pretreatment solution used for the pretreatment and the conductivity used for forming the conductive polymer layer Table 1 shows the types of the dispersion liquid of the conductive polymer and the types of the post-treatment solutions used in the post-treatment after the formation of the conductive polymer layer, and Tables 1 to 8 show the comparative examples 1 to 8. It shows in Table 2. However, these types are indicated by the number for the pretreatment solution and by the symbol for the posttreatment solution. The conductive polymer dispersions (I) and (II) are indicated by (I) and (II).

  With respect to the wound aluminum electrolytic capacitors of Examples 1 to 24 and Comparative Examples 1 to 8 manufactured as described above, ESR and capacitance were measured, and breakdown voltage was measured. The results are shown in Table 3 for Examples 1 to 24 and in Table 4 for Comparative Examples 1 to 8. In addition, the measuring method of ESR, an electrostatic capacitance, and a breakdown voltage is as follows.

ESR:
Using an LCR meter (4284A) manufactured by HEWLETT PACKARD, measurement was performed at 100 kHz under the condition of 25 ° C.
Capacitance:
Using an LCR meter (4284A) manufactured by HEWLETT PACKARD, measurement was performed at 120 Hz under the condition of 25 ° C.
Breakdown voltage:
Using PRK650-2.5 manufactured by Matsusada Precision Co., Ltd., the voltage at the time of breakdown was measured by increasing the voltage at a rate of 1 V / sec under the condition of 25 ° C.

  The measurement of ESR and capacitance is performed for 20 samples for each sample, and the numerical values shown in Table 3 and Table 4 for ESR and capacitance are obtained by calculating the average value of the 20 measured values. Rounded to the second place. In addition, the breakdown voltage was measured for 10 samples for each sample, and the numerical values shown in Tables 3 and 4 for the breakdown voltage were obtained by calculating an average value of 10 measured values and rounding off the decimals. Is.

  As is apparent from the results shown in Tables 3 to 4, the wound aluminum electrolytic capacitors of Examples 1 to 24 (hereinafter sometimes referred to as “capacitors” by simplifying the “wound aluminum electrolytic capacitor”) are: Compared with the capacitors of Comparative Examples 1 to 8, the ESR was low, the capacitance was large, and the breakdown voltage was high.

  That is, prior to forming the conductive polymer layer constituting the solid electrolyte in the capacitor element, from the organic solvent solution in which the cyclic organic compound having at least one hydroxyl group and the high boiling point solvent having a boiling point of 150 ° C. or higher are dissolved. The capacitor element is pretreated with the pretreatment solutions 1 to 12, and after the formation of the conductive polymer layer, the posttreatment is performed with the posttreatment solution A comprising an organic solvent solution in which a cyclic organic compound having at least one hydroxyl group is dissolved. The capacitors of Examples 1 to 24 that were not pretreated with any of the pretreatment solutions 1 to 12 did not contain the capacitors of Comparative Examples 1 and 5 and the cyclic organic compound having at least one hydroxyl group. In place of the cyclic organic compound having at least one hydroxyl group, the capacitors of Comparative Examples 2 and 6 pretreated with the solution 13 No post-treatment with post-treatment solution A was performed after the formation of the capacitors and conductive polymer layers of Comparative Examples 3 and 7 pre-treated with pre-treatment solution 14 in which toluenesulfonic acid having no xyl group was dissolved. Compared to the capacitors of Comparative Examples 4 and 8, the ESR was low, the capacitance was large, and the breakdown voltage was high.

  In the capacitors of Example 3 and Example 4, 3-glycidoxypropyltrimethoxysilane was not added to the pretreatment solution, but 3-glycidoxypropyltrimethoxysilane was pretreated. Although the breakdown voltage is slightly lower than the capacitors of Example 1 and Example 2 added to the solution for use, the breakdown voltage is much higher than the capacitors of Comparative Examples 1 to 8, It can be seen that the addition of a voltage tolerant such as 3-glycidoxypropyltrimethoxysilane is desirable but not necessary.

  Further, 10 pieces of each of the wound aluminum electrolytic capacitors of Examples 1 to 24 and Comparative Examples 1 to 8 (the remainder that was previously used for measuring ESR and capacitance, but not used for measuring breakdown voltage) ESR and capacitance after repeating charge and discharge of 50V, 20A 10,000 times for 2 seconds using PRk650-2.5 and EL1.5k-650V-LGob manufactured by Matsusada Precision Co., Ltd. The charge / discharge characteristics were examined by measuring. The results are shown in Table 5 for Examples 1 to 24 and in Table 6 for Comparative Examples 1 to 8. In addition, the measuring method of ESR and electrostatic capacitance is the same as the above, and the display method of the measured value in Table 5 and Table 6 is the point except having calculated | required the average value of ten measured values, The same as in the case of Table 3 and Table 4 in the above table. The same applies to the following 25th embodiment.

  As is apparent from the results shown in Tables 5 to 6, even after the charge and discharge were repeated 10,000 times, the wound aluminum electrolytic capacitors of Examples 1 to 24 (hereinafter sometimes simply referred to as “capacitors”) Compared with the capacitor | condenser of Comparative Examples 1-8, ESR was low and the electrostatic capacitance was large.

  As is clear from the comparison between the ESR values and capacitance values shown in Tables 5 to 6 and the ESR values and capacitance values shown in Tables 3 to 4, the capacitors of Examples 1 to 24 were compared. Compared to the capacitors of Examples 1 to 8, the increase in ESR and the decrease in capacitance after 10,000 charge / discharge cycles were small, and the charge / discharge characteristics were excellent. That is, after charging and discharging is repeated 10,000 times, the difference in ESR and capacitance between the capacitors of Examples 1 to 24 and the capacitors of Comparative Examples 1 to 8 becomes larger than before the start of charging and discharging. The capacitors of ˜24 were superior in charge / discharge characteristics compared to the capacitors of Comparative Examples 1-8.

  In the capacitor in which the electrolyte is composed of a solid conductive polymer like the capacitors in Examples 1 to 24, the characteristics are likely to deteriorate due to repeated charge and discharge. However, as described above, Examples 1 to 24 The capacitor had excellent charge / discharge characteristics.

[Evaluation with a wound aluminum electrolytic capacitor (2)]
In the evaluation (2) using the wound aluminum electrolytic capacitor, a wound aluminum electrolytic capacitor of a type that does not dry the solvent during post-processing is manufactured, and the present invention is evaluated with the wound aluminum electrolytic capacitor.

Example 25
After etching the surface of the aluminum foil, a lead terminal is attached to the anode on which the dielectric layer is formed by chemical conversion treatment at 200 V, and the lead terminal is attached to the cathode made of aluminum foil. The cathode was wound through a separator to produce a capacitor element.

  The capacitor element was immersed in the pretreatment solution 1 prepared in Preparation Example 1, taken out after 1 minute, and dried at 150 ° C. for 15 minutes for pretreatment.

  Next, the pretreated capacitor element is immersed in the conductive polymer dispersion (I) prepared in Preparation Example (I), taken out after 5 minutes, and dried at 150 ° C. for 30 minutes twice. Repeatedly, a conductive polymer layer was formed.

  And after performing the post-treatment by immersing the capacitor element after forming the conductive polymer layer in the post-treatment solution B prepared in Preparation Example B for the post-treatment solution and taking it out after 1 minute, The wound aluminum electrolytic capacitor of Example 25 was manufactured by packaging with a packaging material.

Examples 26-36
The same procedure as in Example 25 was performed except that the pretreatment solutions 2 to 12 prepared in Preparation Examples 2 to 12 were used in place of the pretreatment solution 1 and the pretreatment was performed separately. The wound aluminum electrolytic capacitors of Examples 26 to 36 were manufactured.

Examples 37-48
The same operations as in Examples 25 to 36 were performed except that the conductive polymer dispersion liquid (II) prepared in Preparation Example (II) was used instead of the conductive polymer dispersion liquid (I). As a result, wound aluminum electrolytic capacitors of Examples 37 to 48 were manufactured.

Comparative Example 9
A wound aluminum electrolytic capacitor of Comparative Example 9 was produced in the same manner as in Example 25 except that the pretreatment with the pretreatment solution 1 was not performed.

Comparative Example 10
The same procedure as in Example 25 was performed except that the pretreatment solution 13 for the comparative example was used in place of the pretreatment solution 1, and the wound aluminum electrolysis of the comparative example 10 was performed. A capacitor was manufactured.

Comparative Example 11
The same procedure as in Example 25 was performed except that the pretreatment solution 14 for the comparative example was used instead of the pretreatment solution 1, and the wound aluminum electrolysis of the comparative example 11 was performed. A capacitor was manufactured.

Comparative Example 12
A wound aluminum electrolytic capacitor of Comparative Example 12 was produced in the same manner as in Example 25 except that no post-treatment with post-treatment solution B was performed.

Comparative Example 13
A wound aluminum electrolytic capacitor of Comparative Example 13 was manufactured in the same manner as in Example 37 except that the pretreatment with the pretreatment solution 1 was not performed.

Comparative Example 14
The same procedure as in Example 37 was performed except that the pretreatment solution 13 for the comparative example was used in place of the pretreatment solution 1, and the wound aluminum electrolysis of the comparative example 14 was performed. A capacitor was manufactured.

Comparative Example 15
The same procedure as in Example 37 was performed except that the pretreatment solution 14 for the comparative example was used in place of the pretreatment solution 1, and the wound aluminum electrolysis of the comparative example 15 was performed. A capacitor was manufactured.

Comparative Example 16
A wound aluminum electrolytic capacitor of Comparative Example 16 was manufactured in the same manner as in Example 37 except that the post-treatment with the post-treatment solution B was not performed.

  About the winding type aluminum electrolytic capacitors of Examples 25 to 48 and Comparative Examples 9 to 16 manufactured as described above, the kind of pretreatment solution used for the pretreatment and the conductivity used for forming the conductive polymer layer The types of polymer dispersion and the types of post-treatment solutions used for post-treatment after formation of the conductive polymer layer are shown in Table 7 for Examples 25-48 and Table 8 for Comparative Examples 9-16. Shown in However, the display method of these types is the same as the case of the said Table 1-2.

  For the wound aluminum electrolytic capacitors of Examples 25 to 48 and Comparative Examples 9 to 16 manufactured as described above, the ESR and capacitance were measured and the breakdown voltage was measured as in the case of Example 1. Was measured. The results are shown in Table 9 for Examples 25-48 and in Table 10 for Comparative Examples 1-8. And the display method to Tables 9-10, such as those ESR value, an electrostatic capacitance value, a breakdown voltage value, is the same as that of the case of the said Tables 3-4.

  As is clear from the results shown in Tables 9 to 10, the wound aluminum electrolytic capacitors of Examples 25 to 48 (hereinafter sometimes referred to as “capacitors” by simplifying the “wound aluminum electrolytic capacitor”) are: Compared to the capacitors of Comparative Examples 9 to 16, the ESR was low, the capacitance was large, and the breakdown voltage was high.

  That is, prior to forming the conductive polymer layer constituting the solid electrolyte in the capacitor element, from the organic solvent solution in which the cyclic organic compound having at least one hydroxyl group and the high boiling point solvent having a boiling point of 150 ° C. or higher are dissolved. The capacitor element is pretreated with the following pretreatment solutions 1 to 12, and after the formation of the conductive polymer layer, a cyclic organic compound having at least one hydroxyl group is dissolved in a high boiling point solvent having a boiling point of 150 ° C. or higher. The capacitors of Examples 25 to 48 post-treated with the post-treatment solution B have at least one of the capacitors of Comparative Examples 9 and 13 that were not pre-treated with any of the pre-treatment solutions 1 to 12 and the hydroxyl group. The capacitors of Comparative Examples 10 and 14 pretreated with the pretreatment solution 13 containing no cyclic organic compound, and at least one hydroxyl group In place of the cyclic organic compound to be formed, the capacitors of Comparative Examples 11 and 15 pretreated with the pretreatment solution 14 in which toluenesulfonic acid having no hydroxyl group was dissolved, and the posttreatment solution B after the formation of the conductive polymer layer Compared with the capacitors of Comparative Example 12 and Comparative Example 16 which were not subjected to post-treatment, the ESR was low, the capacitance was large, and the breakdown voltage was high.

  In addition, each of the wound aluminum electrolytic capacitors of Examples 25 to 48 and Comparative Examples 9 to 16 (the remaining 10 which were used to measure ESR and capacitance but were not used to measure breakdown voltage). Each was stored at 150 ° C. for 250 hours, cooled to 25 ° C., and then ESR and capacitance were measured in the same manner as in Example 1. The results are shown in Table 11 for Examples 25-48 and in Table 12 for Comparative Examples 9-16. In addition, the display method of the measured value to Tables 11-12 is the same as that of the case of the said Tables 5-6.

  As is apparent from the results shown in Tables 11 to 12, the wound aluminum electrolytic capacitors of Examples 25 to 48 (hereinafter sometimes simply referred to as “capacitors”) are compared with the capacitors of Comparative Examples 9 to 16. The ESR was low and the capacitance was large.

  As is clear from the comparison of the ESR values and capacitance values shown in Tables 11 to 12 with the ESR values and capacitance values shown in Tables 9 to 10, the capacitors of Examples 25 to 48 were compared. Compared to the capacitors of Examples 9 to 16, there was little increase in ESR and decrease in capacitance after storage at 150 ° C. for 250 hours, and heat resistance was excellent. That is, after storage at 150 ° C. for 250 hours, the difference in ESR and capacitance between the capacitors of Examples 25 to 48 and the capacitors of Comparative Examples 9 to 16 is larger than that before storage. The capacitor was superior in heat resistance as compared with the capacitors of Comparative Examples 9-16.

  In the synthesis of the conductive polymer, a capacitor that does not use a transition metal salt as an oxidizing agent and substantially uses only a solid such as a conductive polymer as an electrolyte, such as the capacitors of Examples 1 to 24, is heat resistant. However, it is not necessary to take into account the deterioration of the properties, but like the capacitors of Examples 25 to 48, they are in liquid form (that is, high-boiling solvents having a boiling point of 150 ° C. or higher used in the preparation of the post-treatment solution). In the case of a capacitor containing the heat resistance, there is a problem of heat resistance when stored at a high temperature.

  However, the capacitors of Examples 25 to 48 are excellent in heat resistance even if they contain liquid ones, and even when stored at 150 ° C. for 250 hours at a high temperature for a long time, there is little increase in ESR or decrease in capacitance. It was.

Claims (7)

In manufacturing an electrolytic capacitor using a conductive polymer as a solid electrolyte, a porous body of at least one valve metal selected from the group consisting of aluminum, tantalum and niobium and a dielectric layer made of an oxide film of the valve metal When forming a conductive polymer layer on a capacitor element, the organic solvent in which a cyclic organic compound having at least one hydroxyl group and a high boiling point solvent having a boiling point of 150 ° C. or more are dissolved in the capacitor element as a pretreatment. After impregnating the solution, the drying operation is performed at least once,
The capacitor element after the pre-treatment is impregnated with a dispersion of a conductive polymer obtained by oxidative polymerization of thiophene or a derivative thereof with a polymer anion as a dopant, and then dried at least once, whereby a capacitor is obtained. Form a conductive polymer layer on the device,
The capacitor element after forming the conductive polymer layer is impregnated with an organic solvent solution in which a cyclic organic compound having at least one hydroxyl group is dissolved, and then subjected to post-treatment by performing at least one drying operation. The manufacturing method of the electrolytic capacitor characterized by these. In manufacturing an electrolytic capacitor using a conductive polymer as a solid electrolyte, a porous body of at least one valve metal selected from the group consisting of aluminum, tantalum and niobium and a dielectric layer made of an oxide film of the valve metal When forming a conductive polymer layer on a capacitor element, the organic solvent in which a cyclic organic compound having at least one hydroxyl group and a high boiling point solvent having a boiling point of 150 ° C. or more are dissolved in the capacitor element as a pretreatment. After impregnating the solution, the drying operation is performed at least once,
The capacitor element after the pre-treatment is impregnated with a dispersion of a conductive polymer obtained by oxidative polymerization of thiophene or a derivative thereof with a polymer anion as a dopant, and then dried at least once, whereby a capacitor is obtained. Form a conductive polymer layer on the device,
By impregnating the capacitor element after forming the conductive polymer layer with a solution in which a cyclic organic compound having at least one hydroxyl group is dissolved in a high boiling point solvent having a boiling point of 150 ° C. or more is performed at least once. A method for producing an electrolytic capacitor, comprising post-processing.   3. The method for producing an electrolytic capacitor according to claim 1, wherein the cyclic organic compound having at least one hydroxyl group has a carboxyl group.   The method for producing an electrolytic capacitor according to claim 1 or 2, wherein the cyclic organic compound having at least one hydroxyl group has a nitro group.   3. The method for producing an electrolytic capacitor according to claim 1, wherein the cyclic organic compound having at least one hydroxyl group has an alkoxy group.   The method for producing an electrolytic capacitor according to claim 1 or 2, wherein the cyclic organic compound having at least one hydroxyl group has a carboxy group and a nitro group.   The cyclic organic compound having at least one hydroxyl group is at least one selected from the group consisting of hydroxybenzenecarboxylic acid, hydroxybenzenecarboxylic acid alkyl ester, nitrophenol, alkoxyphenol, hydroxynitrobenzenecarboxylic acid and hydroxynitrobenzenecarboxylic acid alkyl ester The method of manufacturing an electrolytic capacitor according to claim 1 or 2, wherein