JP2013055308A - Production method of fluid dispersion for solid electrolytic capacitor, fluid dispersion for solid electrolytic capacitor, manufacturing method of solid electrolytic capacitor using the fluid dispersion and solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing an aqueous dispersion of conductive polymer which can manufacture a solid electrolytic capacitor having a high CR and a low ESR.SOLUTION: A production method of a dispersion for a solid electrolytic capacitor includes a preparation step for obtaining a mixture containing water as a dispersion medium, a water-insoluble or slightly-soluble fine particles of conductive polymer derived from a monomer having a π-conjugated double bond, and a dispersion step for irradiating the mixture with ultrasonic waves having a frequency of 15-100 kHz and then further irradiating the mixture with ultrasonic waves having a frequency of 0.8-4 MHz.

Description

  The present invention relates to a method for producing a dispersion for a solid electrolytic capacitor capable of providing a solid electrolytic capacitor having a high CR and a low ESR, and a dispersion obtained by this method. The present invention also relates to a method for producing a solid electrolytic capacitor having a high CR and a low ESR using the above dispersion, and a solid electrolytic capacitor obtained by this method.

  A solid electrolytic capacitor has an anode in which an oxide film as a dielectric is provided on the surface of a valve metal foil such as aluminum, tantalum, or niobium, and a solid electrolyte layer that is in contact with the oxide film and acts as a true cathode. Contains. In order to form this solid electrolyte layer, conductive polymers derived from monomers having a π-conjugated double bond such as substituted or unsubstituted thiophene, pyrrole, and aniline are widely used.

  By the way, the conductive polymer for forming the solid electrolyte layer includes a water-insoluble or hardly water-soluble conductive polymer such as poly (3,4-ethylenedioxythiophene). As a method for forming such a solid electrolyte layer containing a water-insoluble or poorly water-soluble conductive polymer, the conductive polymer particles are dispersed in water, and the obtained dispersion is allowed to permeate the oxide film of the anode. The drying method is conventionally known. This method can use water with a low environmental impact and excellent economic efficiency as a medium. Also, compared with a method of forming a solid electrolyte layer by chemical polymerization or electrolytic polymerization of a monomer, it is simple and quick. It has the advantage that an electrolyte layer can be obtained, and further, a highly conductive solid polymer layer having a high molecular weight is included in the dispersion to form a solid electrolyte layer with high conductivity. Can do. Therefore, using an aqueous dispersion containing a water-insoluble or poorly water-soluble conductive polymer, the capacity appearance rate CR is high, that is, the capacitance is high, and furthermore, the equivalent series resistance ESR is low, that is, the low impedance. As shown, a method for producing a solid electrolytic capacitor has been studied, and a method of using an aqueous dispersion having a reduced viscosity by applying a dispersion treatment has been proposed.

  For example, Patent Document 1 (Japanese Patent Laid-Open No. 2003-100561) discloses a step of forming a capacitor element by winding an anode and a cathode with a separator interposed therebetween, and a conductive polymer dispersion in the capacitor element. A step of forming a first solid electrolyte layer by impregnating an aqueous solution, and a second solid electrolyte layer by impregnating a mixed solution containing a heterocyclic monomer and an oxidizing agent on the surface of the first solid electrolyte layer A method for producing a solid electrolytic capacitor comprising: a conductive polymer-dispersed aqueous solution for forming a first solid electrolyte layer comprising: conductive polymer fine particles; It is obtained by subjecting an aqueous solution containing an organic polymer binder such as alcohol or polyvinyl acetate and a surfactant to a dispersion treatment.

  Examples of the dispersion processing include processing using a homogenizer, a hybrid mixer, or a high shear mixer in addition to ultrasonic processing using an ultrasonic processing apparatus having a frequency of 40 to 60 kHz and an output of 50 to 100 W. By these dispersion treatments, the dispersibility of the conductive polymer fine particles and the organic polymer binder in the aqueous solution can be increased, and the viscosity of the conductive polymer dispersed aqueous solution can be reduced. And it is shown that the dispersion process using a high shear mixer reduces the viscosity of the conductive polymer dispersion aqueous solution in a short time.

  Conductive polymer with good adhesion to the oxide film on the anode oxide film by dipping the capacitor element in this low-viscosity aqueous conductive polymer dispersion and then drying. Forming a first solid electrolyte layer containing the fine particles and the organic polymer binder, and then immersing the capacitor element in a mixed solution containing a monomer, an oxidizing agent and a polymerization solvent, and then leaving the capacitor element to stand. Thus, a second solid electrolyte layer is formed between the anode and the cathode by chemical oxidative polymerization. Since the compatibility of the organic polymer binder in the first solid electrolyte layer and the conductive polymer generated by chemical oxidative polymerization is high, the coverage of the conductive polymer on the oxide film is increased, and the solid electrolytic capacitor The capacitance increases and the impedance decreases. And the solid electrolytic capacitor which has the highest electrostatic capacitance and the lowest impedance is obtained by use of the dispersion processing liquid by a high shear mixer.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2010-87401) discloses a process for obtaining a capacitor substrate by oxidizing the surface of an anode to form a dielectric layer (oxide film), and the capacitor substrate. Forming a solid electrolyte layer on the surface of the dielectric layer, wherein the solid electrolyte layer is formed on the dielectric layer of the capacitor substrate in the step of forming the solid electrolyte layer. Conducting a conductive polymer solution containing molecules, polyanions, and a solvent, and drying to form a conductive polymer film is repeated twice or more times. Conductivity used for at least one film forming process after the second time. The manufacturing method of the capacitor | condenser characterized by using the high viscosity solution whose viscosity is higher than the conductive polymer solution used for the film-forming process of the 1st time as a conductive polymer solution is disclosed. When a low-viscosity solution is applied to the capacitor substrate in the first film formation process, the solution penetrates into the surface of the porous capacitor substrate to form a first conductive polymer film. The high-viscosity solution for the second and subsequent film formation processes is used to secure the film thickness with a small number of film formations.

  It has been shown that the low viscosity solution used for the first film formation treatment can be obtained by subjecting a conductive polymer solution containing a conductive polymer and a polyanion as essential components to a dispersion treatment. Examples of the dispersion treatment include a high-pressure dispersion method using a high-pressure homogenizer, an ultrasonic dispersion method in which ultrasonic waves of 10 to 50 kHz are irradiated, and a high-speed fluid dispersion method, which are specifically used in the examples. The only dispersion method is the high pressure dispersion method.

  In the examples, an aqueous solution containing 1.7% by mass of polystyrene sulfonic acid / poly (3,4-ethylenedioxythiophene) composite, imidazole as a highly conductive agent and neutralizing agent, and a highly conductive agent. An aqueous dispersion adjusted to a viscosity of 8 to 40 mPa · s by high-pressure dispersion treatment after addition of diethylene glycol is used as a low viscosity solution. The capacitor substrate is immersed in a low-viscosity solution and dried five times to perform the first film-forming treatment, and then immersed in the high-viscosity solution and dried twice to form the second film-forming. By performing the treatment, a solid electrolytic capacitor is obtained. The lower the viscosity of the low-viscosity solution used for the first film formation treatment, the greater the capacitance of the obtained solid electrolytic capacitor and the lower the ESR. The highly conductive agent contained in the aqueous dispersion is widely used in the production of solid electrolytic capacitors for the purpose of improving the conductivity of the solid electrolyte layer.

JP 2003-1000056 A1 JP 2010-87401 A

  Therefore, it is known to constitute at least a part of the solid electrolyte layer of the solid electrolytic capacitor using the aqueous dispersion in which the dispersibility of the water-insoluble or poorly water-soluble conductive polymer is improved by the dispersion treatment, A dispersion treatment method of an aqueous dispersion that can be used is also exemplified. However, the present situation is that detailed examination about each distributed processing method is not performed. On the other hand, since there is always a demand for improvement of CR and reduction of ESR for solid electrolytic capacitors, it is desired to examine a dispersion treatment method of an aqueous dispersion that can meet this demand.

  Further, the method using chemical oxidative polymerization disclosed in Patent Document 1 loses the advantage that a solid electrolyte layer can be obtained easily and quickly in the method using an aqueous dispersion of a conductive polymer. It is desirable that chemical oxidation polymerization not be used.

  Furthermore, generally, the lower the viscosity of the liquid that permeates the anode (capacitor base material) or capacitor element, the smaller the amount of conductive polymer adhering to the anode or capacitor element due to immersion and drying in the liquid per time. In order to obtain a solid electrolytic capacitor having a solid electrolyte layer of the same thickness, the number of repetitions of immersion and drying of the anode or the capacitor element in the liquid must be increased as the liquid having a lower viscosity is used. However, in order to obtain a solid electrolytic capacitor simply and quickly, it is desirable that the number of repetitions is small. Therefore, it is necessary to use a dispersion liquid that gives a solid electrolytic capacitor having a high CR and a low ESR even if the viscosity is relatively high. desirable.

Therefore, an object of the present invention is to study a dispersion treatment condition of an aqueous dispersion on the basis of an aqueous dispersion of a water-insoluble or poorly water-soluble conductive polymer, so that a solid having a higher CR and a lower ESR than conventional ones. It is an object of the present invention to provide a method for producing an electrolytic capacitor simply and quickly without using chemical oxidative polymerization and a dispersion for the method.

  As a result of intensive studies, the inventors have found that water and a water-insoluble or poorly water-soluble conductive polymer derived from a monomer having a π-conjugated double bond (hereinafter referred to as “a monomer having a π-conjugated double bond”). “Water-insoluble or poorly water-soluble conductive polymer” is simply referred to as “water-insoluble conductive polymer” (hereinafter referred to as “aggregate”). The dispersion obtained by irradiating the mixed liquid containing 15 to 100 kHz with an ultrasonic wave having a frequency of 15 to 100 kHz is unexpectedly higher than the liquid obtained by the high-pressure dispersion method. Dispersion obtained by leading to a solid electrolytic capacitor with higher CR and lower ESR despite showing viscosity and further irradiating this dispersion with ultrasound having a frequency of 0.8-4 MHz Liquid is solid It has been discovered that the CR of electrolytic capacitors can be further improved. Production of a solid electrolytic capacitor using a dispersion obtained by continuously irradiating ultrasonic waves having different frequencies has not been known.

  Accordingly, the present invention is first a method for producing a dispersion for a solid electrolytic capacitor comprising water as a dispersion medium and fine particles of a water-insoluble conductive polymer, comprising water and an aggregate of the conductive polymer. A preparation step of obtaining a mixed solution, and a dispersion step of further irradiating an ultrasonic wave having a frequency of 0.8 to 4 MHz after irradiating the mixed liquid with an ultrasonic wave having a frequency of 15 to 100 kHz. The present invention relates to a method for producing a dispersion for a solid electrolytic capacitor.

  When an ultrasonic wave having a frequency of 15 to 100 kHz is irradiated to a mixed solution containing water and an aggregate of water-insoluble conductive polymer, water-insoluble conductive property in the mixed solution is generated by cavitation generated by the ultrasonic wave in this range. Since the polymer aggregates are split and the split fine particles collide with each other, the water-insoluble conductive polymer aggregates are easily refined and the viscosity of the liquid is lowered. The fine water-insoluble conductive polymer fine particles are stably dispersed in water. Cavitation is less likely to occur due to the subsequent irradiation with ultrasonic waves having a frequency of 0.8 to 4 MHz, but the water-insoluble conductive polymer fine particles and water are refined by irradiation with ultrasonic waves having a frequency of 15 to 100 kHz. Since acceleration is applied to the molecules, the fine particles of the water-insoluble conductive polymer collide with each other to further refine the particles, and the viscosity of the liquid slightly decreases. The finer fine particles are stably dispersed in water. The average particle size of the water-insoluble conductive polymer fine particles in the finally obtained dispersion is generally in the range of 30 to 100 nm, preferably 40 to 70 nm. The fine particles of the water-insoluble conductive polymer enter the etching pits in the oxide film of the anode and improve the CR of the solid electrolytic capacitor. The average particle size of the water-insoluble conductive polymer in the dispersion can be measured by a dynamic light scattering method.

  In the present invention, as the water-insoluble conductive polymer, those having a solubility of generally 2 g or less with respect to 1 liter of water, preferably 1 g or less with respect to 1 liter of water can be used. This water-insoluble conductive polymer preferably contains a polymer anion, preferably an anion of polystyrene sulfonic acid (hereinafter referred to as “PSS”) as a dopant. Due to the surface active action of the polymer anion, the fine particles of the water-insoluble conductive polymer are more stably dispersed in water, and the reaggregation of the fine particles is suppressed.

  In the present invention, a known water-insoluble conductive polymer can be used without particular limitation, but water derived from at least one monomer selected from the group consisting of thiophenes having substituents at the 3-position and 4-position. An insoluble conductive polymer exhibits high conductivity and is excellent in heat resistance, and therefore can be preferably used in the present invention. Among them, a cation of poly (3,4-ethylenedioxythiophene) (hereinafter referred to as “PEDOT”), which is a polymer of 3,4-ethylenedioxythiophene (hereinafter referred to as “EDOT”), and an anion of PSS (Hereinafter referred to as “PEDOT / PSS complex”).

  The content of the water-insoluble conductive polymer aggregate in the mixed solution is generally in the range of 1.0 to 2.0% by mass, preferably 1.5% to 2.0% by mass. It is a range. If the content of the water-insoluble conductive polymer is less than 1% by mass of the total liquid mixture, it is considered that the opportunity for collision of aggregates or fine particles is insufficient. It is difficult to obtain a dispersion in which the fine particles are highly dispersed, and the ESR of the obtained solid electrolytic capacitor tends to increase. Moreover, it is not preferable that the content of the water-insoluble conductive polymer exceeds 2.0% by mass of the whole mixed solution because the solution tends to be gelled by ultrasonic irradiation.

  Irradiation of ultrasonic waves having a frequency of 0.8 to 4 MHz is preferably performed twice or more while increasing the frequency of ultrasonic waves as the number of times increases. Since the finer fine particles of the water-insoluble conductive polymer further advance, the fine particles are more likely to enter the etching pits in the oxide film of the anode, and the CR of the obtained solid electrolytic capacitor further increases.

  The dispersion for forming the solid electrolyte layer of the solid electrolytic capacitor preferably contains a high conductivity agent for improving the conductivity of the solid electrolyte layer. In the present invention, a known highly conductive agent can be used without particular limitation. For example, a water-soluble compound having a hydroxy group, a water-soluble compound having an amide group, a water-soluble compound having a lactone group, and a lactam group. At least one compound selected from the group consisting of a water-soluble compound, a water-soluble compound having an ether group, a water-soluble sulfoxide, and a water-soluble sulfone can be used as the highly conductive agent. These highly conductive agents are preferably added to the liquid after ultrasonic irradiation in the dispersion step. This is because depending on the type and concentration of the highly conductive agent, the collision of water-insoluble conductive polymer aggregates or finely divided fine particles during ultrasonic irradiation may be inhibited, or reaggregation may be promoted. As the highly conductive agent, it is particularly preferable to use sorbitol, which is one of water-soluble compounds having a hydroxy group. Sorbitol not only improves the conductivity of the solid electrolyte layer, but also significantly improves the voltage resistance of the solid electrolytic capacitor.

  Some liquid mixtures containing water and water-insoluble conductive polymer aggregates exhibit strong acidity with a pH of less than 3, such as liquid mixtures containing PEDOT / PSS composites. If an attempt is made to produce a solid electrolytic capacitor using a dispersion having a strong acidity, the oxide film on the anode or the electrode member around the capacitor may be corroded. Therefore, in the dispersion step, it is preferable to adjust the pH of the dispersion to a range of 4 to 10 by adding a neutralizing agent to the liquid. When the pH is in the range of 4 or more, corrosion of the oxide film or the like is suppressed, and adhesion between the solid electrolyte layer and the oxide film is increased. However, if the pH exceeds 10, the conductivity of the solid electrolyte layer is lowered due to the desorption of the dopant, which is not preferable. Moreover, since sorbitol especially preferable as a highly conductive agent is stable in a pH range of 4 to 10, it is preferable to adjust the pH to a range of 4 to 10 in order to obtain a sufficient effect of sorbitol.

  According to the method for producing a dispersion for a solid electrolytic capacitor of the present invention, it is possible to obtain a dispersion for a solid electrolytic capacitor that gives a solid electrolytic capacitor having a higher CR and a lower ESR than conventional ones, despite showing a relatively high viscosity. it can. Therefore, the present invention also relates to a dispersion for a solid electrolytic capacitor containing water as a dispersion medium and fine particles of a water-insoluble conductive polymer obtained by the method for producing a dispersion for a solid electrolytic capacitor of the present invention.

  Although the dispersion of the present invention leads to a solid electrolytic capacitor having a high CR and a low ESR despite showing a relatively high viscosity, the solid electrolytic capacitor having a high CR and a low ESR is subjected to chemical oxidative polymerization. It can be suitably used for the purpose of simple and rapid production without use.

  Accordingly, the present invention also provides a solid electrolytic capacitor comprising an anode made of a valve metal foil having an oxide film on the surface, and a solid electrolytic layer containing a water-insoluble conductive polymer provided on the oxide film of the anode. The solid electrolyte layer containing the conductive polymer is formed on the anode oxide film by impregnating the anode oxide film with the dispersion for a solid electrolytic capacitor of the present invention and drying. The present invention relates to a solid electrolytic capacitor manufacturing method including a solid electrolyte layer forming step, and a solid electrolytic capacitor obtained by this method. By this method, a flat solid electrolytic capacitor having a high CR and a low ESR can be obtained simply and quickly.

  The present invention further includes a solid electrolyte layer comprising an anode made of a valve metal foil having an oxide film on the surface thereof, a cathode made of the valve metal foil, and a water-insoluble conductive polymer disposed between the anode and the cathode. A separator for holding a solid electrolytic capacitor, comprising: an anode, the cathode, and a device manufacturing step for obtaining a capacitor element including a separator disposed therebetween; and A solid electrolyte layer that forms the solid electrolyte layer containing the conductive polymer between the oxide film of the anode and the cathode by impregnating the capacitor element with the dispersion for a solid electrolytic capacitor of the present invention and drying. The present invention relates to a method for manufacturing a solid electrolytic capacitor including a forming step, and a solid electrolytic capacitor obtained by the method. By this method of manufacturing a solid electrolytic capacitor, a wound or stacked solid electrolytic capacitor having a high CR and a low ESR can be obtained simply and quickly.

  It is obtained by irradiating an ultrasonic wave having a frequency of 0.8 to 4.0 MHz following irradiation of an ultrasonic wave having a frequency of 15 to 100 kHz to a mixed solution containing water and an aggregate of water-insoluble conductive polymer. The resulting dispersion leads to a solid electrolytic capacitor having a high CR and a low ESR despite showing a relatively high viscosity. Therefore, according to the method for manufacturing a solid electrolytic capacitor of the present invention, a high CR and a low ESR are obtained. Can be produced easily and quickly.

A: Dispersion for solid electrolytic capacitor and method for producing the same In the present invention, a dispersion for solid electrolytic capacitor containing water as a dispersion medium and fine particles of a water-insoluble conductive polymer is used. A preparation step of obtaining a mixed solution containing an aggregate, and a dispersion step of further irradiating the ultrasonic wave having a frequency of 0.8 to 4 MHz after irradiating the ultrasonic wave having a frequency of 15 to 100 kHz to the liquid mixture. It manufactures by the method containing. Hereinafter, each step will be described in detail.

(1) Preparation Step In the present invention, a water-insoluble or poorly water-soluble conductive polymer derived from a monomer having a π-conjugated double bond can be used as the water-insoluble conductive polymer without any particular limitation. Water-insoluble or poorly water-soluble polythiophenes, polypyrroles, polyanilines, polyfurans, polyphenylenes, polyphenylene vinylenes, polyacenes, polythiophene vinylenes, copolymers thereof, and the like can be used.

  Examples of typical monomers are shown below. These monomers may be used alone or as a mixture of two or more.

  First, thiophene and thiophene derivatives can be used. The thiophene derivative is preferably a compound selected from thiophene having substituents at the 3-position and 4-position, and the 3-position and 4-position substituents of the thiophene ring form a ring with the 3-position and 4-position carbon. Also good. Examples include 3-alkylthiophene such as 3-methylthiophene and 3-ethylthiophene, 3,4-dialkylthiophene such as 3,4-dimethylthiophene and 3,4-diethylthiophene, 3-methoxythiophene, 3-ethoxy 3-alkoxythiophene such as thiophene, 3,4-dialkoxythiophene such as 3,4-dimethoxythiophene, 3,4-diethoxythiophene, 3-methyl-4-methoxythiophene, 3-methyl-4-ethoxythiophene, etc. Alkylalkoxythiophene, 3,4-methylenedioxythiophene, EDOT, alkylenedioxythiophene such as 3,4- (1,2-propylenedioxy) thiophene, 3,4-methyleneoxythiathiophene, 3,4- Ethyleneoxythiathiophene, 3, 4 Alkyleneoxythiathiophene such as (1,2-propyleneoxythia) thiophene, 3,4-methylenedithiathiophene, 3,4-ethylenedithiathiophene, 3,4- (1,2-propylenedithia) thiophene, etc. Alkylthieno [3,4-b] such as alkylene dithiathiophene, thieno [3,4-b] thiophene, isopropylthieno [3,4-b] thiophene, t-butyl-thieno [3,4-b] thiophene ] Thiophene, alkylcarboxythiophene such as 3-methyl-4-carboxythiophene, alkylcarboxyalkylthiophene such as 3-methyl-4-carboxyethylthiophene, 3-methyl-4-carboxybutylthiophene, 3-phenylthiophene, 3- Cyanothiophene, 3-hydroxythiophene And 3-carboxy-thiophene may be cited. It is particularly preferable to use EDOT.

  Further, pyrrole and pyrrole derivatives, for example, N-alkyl pyrrole such as N-methyl pyrrole and N-ethyl pyrrole, 3-alkyl pyrrole such as 3-methyl pyrrole and 3-ethyl pyrrole, 3-methoxy pyrrole, 3-ethoxy pyrrole Such as 3-alkoxypyrrole, 3,4-dimethylpyrrole, 3,4-dialkylpyrrole such as 3,4-diethylpyrrole, 3,4-dimethoxypyrrole, 3,4-diethoxypyrrole, etc. Alkoxy pyrrole, alkyl carboxy pyrrole such as 3-methyl-4-carboxy pyrrole, alkyl carboxyalkyl pyrrole such as 3-methyl-4-carboxy ethyl pyrrole, 3-methyl-4-carboxy butyl pyrrole, N-phenyl pyrrole and N- Use naphthylpyrrole Door can be.

  Also, aniline and aniline derivatives such as 2,5-dialkylaniline such as 2,5-dimethylaniline and 2-methyl-5-ethylaniline, 2,5-dimethoxyaniline, 2-methoxy-5-ethoxyaniline and the like 2,3,5-trialkoxyaniline such as 2,5-dialkoxyaniline, 2,3,5-trimethoxyaniline, 2,3,5-triethoxyaniline, 2,3,5,6-tetramethoxyaniline 2,3,5,6-tetraalkoxyaniline such as 2,3,5,6-tetraethoxyaniline can be used.

  Further, furan and furan derivatives, for example, 3-alkyl furan such as 3-methyl furan and 3-ethyl furan, 3,4-dialkyl furan such as 3,4-dimethyl furan and 3,4-diethyl furan, 3-methoxy 3-Alkoxyfuran such as furan and 3-ethoxyfuran, 3,4-dialkoxyfuran such as 3,4-dimethoxyfuran and 3,4-diethoxyfuran can be used.

  The conductive polymer contains a dopant. As the dopant, a known dopant contained in the water-insoluble conductive polymer can be used without any particular limitation, and a single dopant may be used, or two or more kinds of dopants may be mixed and used. . Examples of dopants include first inorganic acids such as boric acid, nitric acid, phosphoric acid, acetic acid, oxalic acid, citric acid, ascot acid, tartaric acid, squaric acid, rhodizone acid, croconic acid, salicylic acid, p-toluenesulfonic acid, 1,2-dihydroxy-3,5-benzenedisulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, borodisalicylic acid, bisoxalate borate acid, sulfonylimide acid, dodecylbenzenesulfonic acid, propylnaphthalenesulfonic acid, butylnaphthalenesulfone Mention may be made of anions of organic acids such as acids.

  Furthermore, a polymer anion can be preferably used as a dopant. Due to the surface active action of the polymer anion, the water-insoluble conductive polymer fine particles are more stably dispersed in water in the following dispersion step, and re-aggregation of the fine particles is suppressed. As the polymer anion, anions of polycarboxylic acids such as polyacrylic acid, polymethacrylic acid and polymaleic acid, and polysulfonic acid anions such as polystyrene sulfonic acid and polyvinyl sulfonic acid can be preferably used.

  The anion of the polycarboxylic acid or the anion of the polysulfonic acid may be an anion of a copolymer of vinylcarboxylic acid and vinylsulfonic acid and other polymerizable monomers such as an acrylate ester and styrene. The anion of polystyrene sulfonic acid is particularly preferred. The number average molecular weight of the polymer anion is 1,000 to 2,000,000, preferably 10,000 to 500,000. If the number average molecular weight is less than 1,000, the resulting conductive polymer lacks conductivity, and the dispersibility is lowered, which is not preferable. If the number average molecular weight exceeds 2,000,000, the viscosity of the mixed solution is not preferable. Is unfavorable because of an increase.

  As the liquid mixture containing the water-insoluble conductive polymer aggregate and water, those prepared by a known method can be used without particular limitation.

  For example, add monomer, acid or alkali metal salt releasing dopant and oxidizing agent to water, stir until chemical oxidative polymerization is complete, then ultrafiltration, cation exchange, and anion The mixed liquid can be obtained by removing the oxidant and the residual monomer by a purification means such as exchange. When an acid or an alkali metal salt thereof that releases a polymer anion is used, it is generally used in an amount of 0.25 to 10 anionic groups per mole of monomer. Examples of the oxidizing agent include trivalent iron salts such as iron (III) p-toluenesulfonate, iron (III) naphthalenesulfonate, and iron (III) anthraquinonesulfonate, or peroxodisulfuric acid, ammonium peroxodisulfate, and peroxodisulfuric acid. A peroxodisulfate such as sodium sulfate can be used, and a single compound may be used, or two or more compounds may be used. The polymerization temperature is not strictly limited, but is generally in the range of 10 to 60 ° C. The polymerization time is generally in the range of 10 minutes to 30 hours.

In addition, the monomer and the acid or alkali metal salt releasing the dopant are added to water, and electrolytic oxidation polymerization is performed with stirring, and then the residue remains by purification means such as ultrafiltration, cation exchange, and anion exchange. The mixed liquid can also be obtained by removing the monomer. When an acid or an alkali metal salt thereof that releases a polymer anion is used, it is generally used in an amount of 0.25 to 10 anionic groups per mole of monomer. The electrolytic polymerization is performed by any one of a constant potential method, a constant current method, and a potential sweep method. In the case of the constant potential method, a potential of 1.0 to 1.5 V is suitable for the saturated calomel electrode, and in the case of the constant current method, a current value of 1 to 10000 μA / cm ² is suitable. In the case of the potential sweep method, it is preferable to sweep a range of 0 to 1.5 V with respect to the saturated calomel electrode at a speed of 5 to 200 mV / sec. The polymerization temperature is not strictly limited, but is generally in the range of 10 to 60 ° C. The polymerization time is generally in the range of 10 minutes to 30 hours.

  Furthermore, the liquid obtained by the above-described chemical oxidative polymerization method or electrolytic polymerization method may be filtered to separate aggregates, washed thoroughly, and then added to water to prepare a mixed solution.

  The mixed solution of water and water-insoluble conductive polymer aggregate used in the present invention preferably does not contain an organic polymer binder such as polyvinyl alcohol, polyvinyl acetate, polycarbonate, polyacrylate, or polymethacrylate. . Depending on the type and concentration of the organic polymer binder, the following dispersion process may inhibit the collision of water-insoluble conductive polymer aggregates or finely divided particles during ultrasonic irradiation, or promote reaggregation: Because there is.

  The content of the water-insoluble conductive polymer aggregate in the mixed solution is generally in the range of 1.0 to 2.0% by mass, preferably 1.5% to 2.0% by mass. It is a range. If the content of the water-insoluble conductive polymer is less than 1% by mass of the entire mixture, it is considered that the opportunity for collision of aggregates or fine particles is insufficient in the following dispersion step. It is difficult to obtain a dispersion in which fine particles of a water-insoluble conductive polymer are highly dispersed, and ESR of the obtained solid electrolytic capacitor tends to increase. Moreover, it is not preferable that the content of the water-insoluble conductive polymer exceeds 2.0% by mass of the whole mixed solution because the solution tends to be gelled by ultrasonic irradiation in the following dispersion step. There is no strict restriction on the particle size of the water-insoluble conductive polymer aggregate, and it is easily refined in the following dispersion step. The average particle size of the aggregate is generally 400 nm to 10 μm, preferably It is in the range of 400 nm to 1 μm.

(2) Dispersion process By irradiating the mixed liquid obtained in the preparation process with ultrasonic waves having a frequency in a specific range, the water-insoluble conductive polymer aggregates are refined, and the refined fine particles are increased in water. Disperse.

In this step, first, an ultrasonic wave having a frequency of 15 to 100 kHz that can generate cavitation of several hundred nm to several μm having a strong mechanical action is irradiated. The output of an ultrasonic wave having a frequency in this range is preferably 4 W / cm ² or more. When the mixed liquid is irradiated with ultrasonic waves having a frequency of 15 to 100 kHz, the aggregates of the water-insoluble conductive polymer in the mixed liquid are split by the cavitation generated by the ultrasonic waves, and the split fine particles collide with each other. Therefore, the aggregate of the water-insoluble conductive polymer is easily split and refined, and the viscosity of the liquid is lowered. The fine water-insoluble conductive polymer fine particles are dispersed in water. As a result, a dispersion in which water-insoluble conductive polymer fine particles are stably dispersed in water is obtained.

  As an ultrasonic oscillator that is used for irradiation of ultrasonic waves having a frequency of 15 to 100 kHz, an ultrasonic oscillator that is conventionally known as an ultrasonic cleaner, a cell crusher, or the like is used without particular limitation. be able to. The ultrasonic irradiation time is not strictly limited, and the aggregate of the water-insoluble conductive polymer is divided into fine particles even if it is about 1 minute, but it is preferably in the range of 2 to 10 minutes. When the ultrasonic irradiation time is 10 minutes or more, a tendency for the dispersion effect to saturate is observed. The temperature of the liquid mixture at the time of ultrasonic irradiation is not particularly limited as long as the composition of the liquid does not change and a stable dispersion can be obtained, but it is generally in the range of 10 to 60 ° C.

Irradiation of ultrasonic waves having a frequency of 15-100 kHz may be performed once, for example, using ultrasonic waves having a frequency of 20 kHz and an output of 10 W / cm ² , but different frequencies and / or outputs. Multiple times (e.g., using an ultrasound with a frequency of 20 kHz and an output of 10 W / cm < ² > followed by an ultrasound with a frequency of 50 kHz and an output of 20 W / cm < ² >). You can also.

In this invention, the ultrasonic wave which has a frequency of 0.8-4 MHz is irradiated following the irradiation of the ultrasonic wave which has a frequency of 15-100 kHz. The output of the ultrasonic wave having a frequency of 0.8 to 4 MHz is preferably 5 W / cm ² or more. When a solid electrolytic capacitor is manufactured using a dispersion liquid irradiated with ultrasonic waves having a frequency in this range, the CR of the capacitor increases.

  Cavitation is less likely to occur with irradiation of ultrasonic waves having a frequency of 0.8 to 4 MHz, but water-insoluble conductive polymer fine particles and water molecules refined by irradiation with ultrasonic waves having a frequency of 15 to 100 kHz Since acceleration is applied to the water, the fine particles of the water-insoluble conductive polymer collide and further refine. The average particle size of the water-insoluble conductive polymer fine particles in the finally obtained dispersion is generally in the range of 30 to 100 nm, preferably 40 to 70 nm. The further refined fine particles are stably dispersed in water.

  As an ultrasonic oscillator used for irradiation of an ultrasonic wave having a frequency of 0.8 to 4 MHz, an ultrasonic oscillator conventionally known as an ultrasonic cleaner, a cell grinder, or the like is not particularly limited. Can be used. The ultrasonic irradiation time is not strictly limited but is preferably in the range of 2 to 10 minutes. When the ultrasonic irradiation time is 10 minutes or more, a tendency to saturate the effect of miniaturization is recognized. The temperature of the dispersion during ultrasonic irradiation is not particularly limited as long as the composition of the liquid does not change and a stable dispersion can be obtained, but is generally in the range of 10 to 60 ° C.

Irradiation of ultrasonic waves having a frequency of 0.8-4 MHz may be performed once, for example using ultrasonic waves having a frequency of 1 MHz and an output of 20 W / cm ² , but different frequencies and / or Perform multiple times using output ultrasound (eg, using 1 MHz frequency and 20 W / cm ² output followed by 2 MHz frequency and 10 W / cm ² output) It is also possible to carry out multiple times under the condition that the frequency of the ultrasonic wave increases as the number of times increases. Since the finer fine particles of the water-insoluble conductive polymer further advance, the CR of the obtained capacitor further increases.

  Among mixed liquids containing water and water-insoluble conductive polymer aggregates obtained in the preparation step, those having strong acidity with a pH of less than 3, such as mixed liquids containing PEDOT / PSS composites However, if an attempt is made to produce a solid electrolytic capacitor using such a dispersion having strong acidity, the oxide film on the anode or the electrode member around the capacitor may be corroded. Therefore, it is preferable to adjust the pH of the liquid to a range of 4 to 10 by adding a neutralizing agent before ultrasonic irradiation, during ultrasonic irradiation, or after ultrasonic irradiation. When the pH is in the range of 4 or more, corrosion of the oxide film or the like is suppressed, and adhesion between the solid electrolyte layer and the oxide film increases. However, if the pH exceeds 10, the conductivity of the solid electrolyte layer decreases due to the desorption of the dopant. Further, as shown below, the dispersion of the present invention preferably contains a highly conductive agent, and sorbitol is a particularly preferable highly conductive agent. Since sorbitol is stable in a pH range of 4 to 10, it is preferable to adjust the pH to a range of 4 to 10 in order to obtain a sufficient effect of sorbitol.

  Usable neutralizers include ammonia, water-soluble alkylamines such as ethylamine and diethylamine, water-soluble arylamines such as aniline and benzylamine, water-soluble heterocyclic amines such as pyridine and imidazole, sodium hydroxide and Alkali metal or alkaline earth metal hydroxides such as calcium hydroxide, alkali metal or alkaline earth metal carbonates such as sodium carbonate and calcium carbonate, alkali metals such as sodium methoxide and calcium methoxide or Examples thereof include alkoxides of alkaline earth metals. These neutralizing agents may be used alone or in combination of two or more neutralizing agents.

  In the dispersion liquid of the present invention, it is preferable to add a high conductivity agent to the liquid in order to improve the conductivity of the solid electrolyte layer and to lower the ESR of the solid electrolytic capacitor. The highly conductive agent is added before the ultrasonic irradiation, during the ultrasonic irradiation, or after the ultrasonic irradiation, but is preferably added to the dispersion after the ultrasonic irradiation. This is because depending on the type and concentration of the highly conductive agent, the collision of water-insoluble conductive polymer aggregates or finely divided fine particles during ultrasonic irradiation may be inhibited, or reaggregation may be promoted.

  In the present invention, a known highly conductive agent can be used without any particular limitation. Below, the compound used as a highly conductive agent is illustrated.

  First, a water-soluble compound having a hydroxy group in the molecule can be used as a highly conductive agent. Examples include polyhydric alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, glycerol and 1,3-butanediol; sugars such as glucose, sucrose, fructose and lactose; tartaric acid, glyceric acid, citric acid and glucar Hydroxy acids such as acids; sugar alcohols such as sorbitol, mannitol, dulcitol and iditol. In particular, sorbitol is a preferred high-conductivity agent because it improves the electrical conductivity of the solid electrolyte layer and significantly improves the voltage resistance of the solid electrolytic capacitor.

  Further, a water-soluble compound having an amide group in the molecule can be used as a highly conductive agent. Examples include N-methylformamide, N, N-dimethylformamide, N-methylacetamide and N, N-dimethylacetamide. Further, water-soluble compounds having a lactone group such as γ-butyrolactone and γ-valerolactone, water-soluble compounds having a lactam group such as N-methylpyrrolidone, 2-pyrrolidone, N-vinyl-2-pyrrolidone and caprolactam It can be used as a highly conductive agent.

  Furthermore, water-soluble compounds having an ether group such as tetrahydrofuran, dioxane and diethyl ether, water-soluble sulfones such as dimethyl sulfone, diethyl sulfone and sulfolane, water-soluble sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide are used as highly conductive agents. Can be used. Also, pyridine, 2-methylpyridine, imidazole, 2-methylimidazole, 2-amino-pyrimidine, 2-amino-4-methylpyrimidine, pyrazine, 2-methylpyrazine, 1,3,5-triazine and 2-amino- Heterocyclic amines such as 1,3,5-triazine can be used as highly conductive agents, and these can also serve as neutralizing agents.

  These highly conductive agents may be used alone or in combination of two or more highly conductive agents. The amount of the highly conductive agent added is generally 0.1 to 20 times, preferably 0.2 to 10 times the mass of the water-insoluble conductive polymer. In addition, you may add conventional additives, such as surfactant, an antifoamer, a coupling agent, antioxidant, a ultraviolet absorber, to a dispersion liquid.

  By the preparation step and the dispersion step described above, the dispersion for a solid electrolytic capacitor of the present invention containing water as a dispersion medium and fine particles of a water-insoluble conductive polymer can be obtained.

B: Solid electrolytic capacitor and manufacturing method thereof The anode oxide film made of a valve metal foil having an oxide film on the surface is infiltrated with the dispersion liquid for a solid electrolytic capacitor of the present invention and dried, and is insoluble in water on the anode oxide film. By performing a solid electrolyte layer forming step of forming a solid electrolyte layer containing a conductive polymer, the anode, and a solid electrolyte layer containing a water-insoluble conductive polymer provided on the oxide film of the anode, The solid electrolytic capacitor of the 1st form provided with can be obtained. In addition, an element manufacturing step for obtaining a capacitor element including an anode made of a valve metal foil having an oxide film on the surface, a cathode made of a valve metal foil, and a separator disposed therebetween, and the capacitor element A solid electrolyte layer forming step of forming a solid electrolyte layer containing a water-insoluble conductive polymer between the oxide film of the anode and the cathode is performed by infiltrating and drying the dispersion for a solid electrolytic capacitor of the invention. Thus, it is possible to obtain a solid electrolytic capacitor according to a second embodiment including the anode, the cathode, and a separator holding a solid electrolyte layer including a water-insoluble conductive polymer disposed therebetween. it can. Hereinafter, each of the solid electrolytic capacitor of the first form and the solid electrolytic capacitor of the second form will be described.

(A) Solid electrolytic capacitor of the first form In the production of the solid electrolytic capacitor of the first form, as the anode, a valve metal foil such as aluminum foil, tantalum foil, niobium foil, titanium foil, preferably aluminum foil, A chemical or electrochemical method is used to expand the surface, and then a chemical conversion treatment is performed using an aqueous solution of ammonium adipate or an aqueous solution of ammonium phosphate to form an oxide film on the surface of the valve metal foil. Is used.

  Then, after applying the dispersion for solid electrolytic capacitor of the present invention to at least the oxide film of the anode by brush coating, dropping coating, dip coating, spray coating or the like, and allowing the dispersion to penetrate into the oxide film, generally 150 ° C. As described above, preferably by drying at a temperature of 180 ° C. or higher, a solid electrolyte layer containing a water-insoluble conductive polymer and a highly conductive agent added as necessary is formed on at least the oxide film of the anode. . Thereafter, a conductive layer (apparent cathode) is formed on the solid electrolyte layer with carbon paste, silver paste, or the like to obtain a solid electrolytic capacitor of the first form. It is also possible to make a hybrid type capacitor by infiltrating the electrolyte into the solid electrolyte layer.

(B) Solid Electrolytic Capacitor of Second Form In the manufacture of the solid electrolytic capacitor of the second form, first, an anode made of a valve metal foil having an oxide film on the surface, a cathode made of the valve metal foil, and the anode An element creating step for obtaining a capacitor element including a separator disposed between the cathode and the cathode is performed.

  As the anode, as in the anode of the solid electrolytic capacitor of the first embodiment, a valve metal foil such as an aluminum foil, a tantalum foil, a niobium foil, or a titanium foil, preferably an aluminum foil, is chemically or electrochemically used. The surface of the valve metal foil is formed by performing chemical treatment using an adipate aqueous solution, an ammonium phosphate aqueous solution, or the like by performing an etching treatment by a technique and further performing chemical conversion treatment using an aqueous solution of ammonium adipate or an aqueous solution of ammonium phosphate. As the cathode, a valve metal foil such as an aluminum foil, a tantalum foil, a niobium foil, a titanium foil, and preferably an aluminum foil, which has been subjected to etching treatment by a chemical or electrochemical technique, is used. The As the separator, Manila paper, kraft paper, synthetic fiber paper, glass paper, glass paper and manila paper, mixed paper of kraft paper, or the like can be used.

  A capacitor element is obtained by winding or laminating an anode and a cathode via a separator. Next, the dispersion for solid electrolytic capacitor of the present invention is infiltrated into the capacitor element by dip coating, drop coating, etc., and generally dried at a temperature of 150 ° C. or higher, preferably 180 ° C. or higher, so that at least the anode oxide film and A solid electrolyte layer containing a water-insoluble conductive polymer and a highly conductive agent added as necessary is formed between the cathode and the cathode, thereby obtaining a solid electrolytic capacitor of the second form. It is also possible to make a hybrid type capacitor by infiltrating the electrolyte into the solid electrolyte layer.

  EXAMPLES Hereinafter, although this invention is demonstrated using an Example, this invention is not limited to a following example.

(1) Solid electrolytic capacitor of the first embodiment Example 1
25 g of a mixed solution in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 2% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes, and further at a frequency of 2 Ultrasonic waves of 4 MHz and output of 7 W / cm ² were irradiated for 5 minutes. It was 52.4 nm when the average particle diameter of the fine particle of PEDOT / PSS was measured about the obtained liquid with the dynamic light-scattering apparatus. Moreover, it was 23.3 mPa * s when the viscosity of the liquid was measured with the vibration viscometer. Next, 2.5 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a conductive agent is added, and aqueous dispersion is added to adjust the pH to 8 to form a dispersion for forming a solid electrolyte layer Got.

The etched aluminum foil was converted to a film withstand voltage of 3 V and then punched out to a projected area of 1 × 1 cm ² to form an anode. After adding 100 μL of the above dispersion to this anode, PEDOT / PSS and sorbitol are contained on the oxide film of the anode by drying at 60 ° C. for 1 hour, 130 ° C. for 30 minutes, and further at 180 ° C. for 1 hour. A solid electrolyte layer was formed. Finally, a carbon paste was applied onto the solid electrolyte layer and dried, and then a silver paste was applied and dried to obtain a solid electrolytic capacitor having an anode with a film withstand voltage of 3V.

  About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Example 2
25 g of a mixed solution in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 2% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then ultrasonic waves with a frequency of 20 kHz and an output of 50 W / cm ² were irradiated for 5 minutes, and then ultrasonic waves with a frequency of 1.6 MHz and an output of 20 W / cm ² were irradiated for 5 minutes. With respect to the obtained liquid, the average particle diameter of the fine particles of PEDOT / PSS was measured by a dynamic light scattering apparatus, and it was 54.7 nm. Moreover, it was 24.6 mPa * s when the viscosity of the liquid was measured with the vibration viscometer. Next, 2.5 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a conductive agent is added, and aqueous dispersion is added to adjust the pH to 8 to form a dispersion for forming a solid electrolyte layer Got.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Example 3
25 g of a mixed solution was prepared in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 1.5% by mass. Next, the mixture was stirred with a stirring homogenizer, and then an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes, and further at a frequency of 2 Ultrasonic waves of 4 MHz and output of 7 W / cm ² were irradiated for 5 minutes. When the viscosity of this liquid was measured, it was 10.7 mPa · s. Next, 1.875 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a conductive agent is added, and aqueous dispersion is added to adjust the pH to 8 to form a dispersion for forming a solid electrolyte layer Got.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Example 4
25 g of a mixed solution in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed in water at a concentration of 1.0% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes, and further at a frequency of 2 Ultrasonic waves of 4 MHz and output of 7 W / cm ² were irradiated for 5 minutes. When the viscosity of this liquid was measured, it was 7.5 mPa · s. Subsequently, 1.25 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a conductive agent is added, and aqueous dispersion is added to adjust the pH to 8 to form a dispersion for forming a solid electrolyte layer Got.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Example 5
The procedure of Example 1 was repeated except that 1.25 g of dimethyl sulfoxide was added instead of 2.5 g of sorbitol. Table 1 shows the capacity appearance rate at 120 Hz and the ESR at 100 kHz for the obtained solid electrolytic capacitor.

Example 6
The procedure of Example 1 was repeated except that 1 g of sorbitol, 2.5 g of ethylene glycol, and 0.25 g of polyethylene glycol with a molecular weight of 200 were added instead of 2.5 g of sorbitol. Table 1 shows the capacity appearance rate at 120 Hz and the ESR at 100 kHz for the obtained solid electrolytic capacitor.

Comparative Example 1
25 g of a mixed solution in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 2% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then irradiated with ultrasonic waves having a frequency of 20 kHz and an output of 50 W / cm ² for 5 minutes. It was 74.7 nm when the average particle diameter of the fine particle of PEDOT / PSS was measured about the obtained liquid with the dynamic light-scattering apparatus. Moreover, it was 26.4 mPa * s when the viscosity of the liquid was measured with the vibration viscometer. Next, 2.5 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a conductive agent is added, and aqueous dispersion is added to adjust the pH to 8 to form a dispersion for forming a solid electrolyte layer Got. The viscosity of the obtained dispersion was 27.0 mPa · s.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 2
25 g of a mixed solution in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 2% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then irradiated with ultrasonic waves having a frequency of 20 kHz and an output of 50 W / cm ² for 5 minutes. It was 74.7 nm when the average particle diameter of the fine particle of PEDOT / PSS was measured about the obtained liquid with the dynamic light-scattering apparatus. Moreover, it was 26.4 mPa * s when the viscosity of the liquid was measured with the vibration viscometer. Next, 1 g of sorbitol, 2.5 g of ethylene glycol, and 0.25 g of polyethylene glycol having a molecular weight of 200 are added, and ammonia water is added to adjust the pH to 8 to obtain a dispersion for forming a solid electrolyte layer. It was.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 3
25 g of a mixed solution in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 2% by mass was prepared. After stirring this liquid mixture with a stirring homogenizer, the viscosity of the liquid was measured and found to be 88.8 mPa · s. To this solution, 1 g of sorbitol as a high conductivity agent, 2.5 g of ethylene glycol, and 0.25 g of polyethylene glycol having a molecular weight of 200 are added, and ammonia water is further added to adjust the pH to 8, and a solid electrolyte layer is formed. A dispersion for forming was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 4
25 g of a mixed solution in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 2% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then irradiated with ultrasonic waves having a frequency of 200 kHz and an output of 50 W / cm ² for 5 minutes. Subsequently, 1 g of sorbitol as a high conductivity agent, 2.5 g of ethylene glycol, and 0.25 g of polyethylene glycol having a molecular weight of 200 were added. Ammonia water was added to this liquid to adjust the pH to 8, and a dispersion for forming a solid electrolyte layer was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 5
25 g of a mixed solution in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 2% by mass was prepared. Next, the mixed solution was stirred with a stirring homogenizer, and then irradiated with ultrasonic waves having a frequency of 20 kHz and an output of 50 W / cm ² , and then ultrasonic waves having an output of 200 kHz and an output of 50 W / cm ² for 5 minutes. Subsequently, 1 g of sorbitol as a high conductivity agent, 2.5 g of ethylene glycol, and 0.25 g of polyethylene glycol having a molecular weight of 200 were added. Ammonia water was added to this liquid to adjust the pH to 8, and a dispersion for forming a solid electrolyte layer was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 6
25 g of a mixed solution in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 2% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then irradiated with ultrasonic waves having a frequency of 1.6 MHz and an output of 20 W / cm ² for 5 minutes. Subsequently, 1 g of sorbitol as a high conductivity agent, 2.5 g of ethylene glycol, and 0.25 g of polyethylene glycol having a molecular weight of 200 were added. Ammonia water was added to this liquid to adjust the pH to 8, and a dispersion for forming a solid electrolyte layer was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 7
25 g of a mixed solution in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 2% by mass was prepared. Next, the mixed solution was stirred with a stirring homogenizer, and then irradiated with ultrasonic waves having a frequency of 2.4 MHz and an output of 7 W / cm ² for 5 minutes. Subsequently, 1 g of sorbitol as a high conductivity agent, 2.5 g of ethylene glycol, and 0.25 g of polyethylene glycol having a molecular weight of 200 were added. Ammonia water was added to this liquid to adjust the pH to 8, and a dispersion for forming a solid electrolyte layer was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 8
A liquid mixture was prepared in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 0.5% by mass. Next, this mixed solution was stirred with a stirring homogenizer, and then passed through a high-pressure homogenizer (product name: Starburst Mini (manufactured by Sugino Machine Co., Ltd.)) 20 times under a condition of 200 MPa, thereby performing a high-pressure dispersion treatment. Further, the obtained liquid was concentrated to obtain a liquid in which PEDOT / PSS was dispersed in water at a concentration of 2% by mass. The viscosity of the obtained liquid was 12 mPa · s. Next, 2.5 g of sorbitol (PEDOT / PSS: sorbitol = 17: 83) as a highly conductive agent is added to 25 g of the obtained liquid, and the pH is adjusted to 8 by adding aqueous ammonia to obtain a solid electrolyte. A dispersion for forming a layer was obtained. The viscosity of the obtained dispersion was 15 mPa · s.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 9
A liquid mixture was prepared in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 0.5% by mass. Next, this mixed solution was stirred with a stirring homogenizer, and then passed through a high-pressure homogenizer (product name: Starburst Mini (manufactured by Sugino Machine Co., Ltd.)) under a condition of 100 MPa for high pressure dispersion treatment. Further, the obtained liquid was concentrated to obtain a liquid in which PEDOT / PSS was dispersed in water at a concentration of 2% by mass. The viscosity of the obtained liquid was 25.4 mPa · s. Next, 2.5 g of sorbitol (PEDOT / PSS: sorbitol = 17: 83) as a highly conductive agent is added to 25 g of the obtained liquid, and the pH is adjusted to 8 by adding aqueous ammonia to obtain a solid electrolyte. A dispersion for forming a layer was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 10
A liquid mixture was prepared in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 0.5% by mass. Next, this mixed solution was stirred with a stirring homogenizer, and then passed through a high-pressure homogenizer (product name: Starburst Mini (manufactured by Sugino Machine Co., Ltd.)) 20 times under a condition of 200 MPa, thereby performing a high-pressure dispersion treatment. Furthermore, the obtained liquid was concentrated, and a liquid in which PEDOT / PSS was dispersed in water at a concentration of 1.5% by mass was obtained. The viscosity of the obtained liquid was 10.1 mPa · s. Next, 1.875 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a highly conductive agent is added to 25 g of the obtained liquid, and the pH is adjusted to 8 by adding aqueous ammonia to obtain a solid electrolyte. A dispersion for forming a layer was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

Comparative Example 11
A liquid mixture was prepared in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 0.5% by mass. Next, this mixed solution was stirred with a stirring homogenizer, and then passed through a high-pressure homogenizer (product name: Starburst Mini (manufactured by Sugino Machine Co., Ltd.)) 20 times under a condition of 200 MPa, thereby performing a high-pressure dispersion treatment. Further, the obtained liquid was concentrated to obtain a liquid in which PEDOT / PSS was dispersed in water at a concentration of 1.0% by mass. The viscosity of the obtained liquid was 7.5 mPa · s. Next, 1.25 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a highly conductive agent is added to 25 g of the obtained liquid, and ammonia water is added to adjust the pH to 8 to obtain a solid electrolyte. A dispersion for forming a layer was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 3 V was obtained in the same manner as in Example 1. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 1.

  From the comparison between Comparative Example 2 and Comparative Example 3, by irradiating the mixed liquid with ultrasonic waves having a frequency of 20 kHz, the average particle diameter of the fine particles of PEDOT / PSS in the liquid was significantly reduced (300 nm to 1 μm → 74 7 nm) and the viscosity of the liquid is also greatly reduced (88.8 mPa · s → 26.4 mPa · s). And when the dispersion liquid which performed the irradiation of the ultrasonic wave which has a frequency of 20 kHz was used, CR of a solid electrolytic capacitor raised significantly and ESR fell significantly. However, according to the comparison between Comparative Example 3 and Comparative Examples 4, 6, and 7, even when a dispersion obtained by irradiating the mixture with ultrasonic waves of 200 kHz, 1.6 MHz, or 2.4 MHz is used, It can be seen that there is almost no increase or decrease in ESR. In order to manufacture a solid electrolytic capacitor having a high CR and a low ESR, first, the mixed solution is irradiated with ultrasonic waves having a frequency of 15 to 100 kHz that can generate cavitation with a strong mechanical action. Shows that it is important.

  On the other hand, from the comparison between Examples 1 and 2 and Comparative Example 1, the mixed solution was irradiated with ultrasonic waves having a frequency of 20 kHz, followed by ultrasonic waves having a frequency of 1.6 MHz, and further a frequency of 2.4 MHz. Although the average particle size of the fine particles of PEDOT / PSS in the liquid further decreases (74.7 nm → 54.7 nm → 52.4 nm), the degree of decrease in the viscosity of the dispersion is slight. It can be seen that (26.4 mPa · s → 24.6 mPa · s → 23.3 mPa · s). In addition, when a dispersion liquid irradiated with ultrasonic waves having a frequency of 1.6 MHz or 2.4 MHz is used subsequent to irradiation with ultrasonic waves having a frequency of 20 kHz, the ESR of the solid electrolytic capacitor is not substantially changed. It can be seen that is further improved. However, from the comparison between Comparative Example 2 and Comparative Example 5, even when a dispersion liquid in which an ultrasonic wave having a frequency of 20 kHz is irradiated to the mixed liquid and then an ultrasonic wave having a frequency of 200 kHz is used, solid electrolytic It can be seen that there is almost no improvement in the CR of the capacitor. This is because, in order to obtain a solid electrolytic capacitor having a higher CR, after irradiating the mixed liquid with ultrasonic waves having a frequency of 15 to 100 kHz capable of generating cavitation with strong mechanical action, the finer This indicates that it is important to irradiate ultrasonic waves having a frequency of 0.8 to 4 MHz that can load sufficient acceleration to the converted PEDOT / PSS fine particles and water molecules.

  In addition, Examples 1 and 2 (and Comparative Example 1) and Comparative Example 8 using a dispersion having a PEDOT / PSS content of 2.0% by mass in the liquid mixture, and the content of PEDOT / PSS in the liquid mixture From the comparison between Example 3 and Comparative Example 10 using the dispersion having an amount of 1.5% by mass, when the dispersion subjected to ultrasonic dispersion treatment is used, the dispersion subjected to dispersion treatment using a high-pressure homogenizer is obtained. It can be seen that a capacitor having a high CR and a low ESR can be obtained despite the higher viscosity of the dispersion than using it. In the comparison between Example 4 and Comparative Example 11 using the dispersion liquid having a PEDOT / PSS content of 1.0 mass% in the mixed liquid, the dispersion liquid had the same viscosity, but the ultrasonic dispersion treatment was performed. Capacitors having a high CR and a low ESR are obtained by using the applied dispersion, rather than using the dispersion subjected to the dispersion treatment by the high-pressure homogenizer. Further, in the comparison between Examples 1 and 2 and Comparative Example 9 using the dispersion having a PEDOT / PSS content of 2.0% by mass in the mixed solution, a dispersion having substantially the same viscosity was used. Nevertheless, a capacitor having a high CR and a low ESR is obtained by using a dispersion liquid subjected to ultrasonic dispersion treatment, compared to using a dispersion liquid subjected to dispersion treatment by a high-pressure homogenizer.

  In general, when a dispersion having a high viscosity is used, a solid electrolytic mass adhering to the oxide film increases due to the permeation and drying of the dispersion into the oxide film of the anode per time in the manufacture of a capacitor. In order to obtain a solid electrolytic capacitor having a solid electrolyte layer, the higher the viscosity of the liquid, the smaller the number of repetitions of immersing and drying the anode in the liquid, and thus the faster the solid electrolytic capacitor is obtained. be able to. When the PEDOT / PSS content in the mixture is 1.5% by mass or more, the dispersion subjected to ultrasonic dispersion treatment has a higher viscosity than the dispersion subjected to dispersion treatment using a high-pressure homogenizer. Nevertheless, in order to provide a solid electrolytic capacitor having higher CR and lower ESR, the method of manufacturing a solid electrolytic capacitor of the present invention is suitable for rapidly manufacturing a capacitor.

From comparison between Example 1 and Examples 5 and 6, ultrasonic waves with a frequency of 20 kHz and an output of 50 W / cm ² were applied to the mixed solution for 5 minutes, and then ultrasonic waves with a frequency of 1.6 MHz and an output of 20 W / cm ² were applied for 5 minutes. Furthermore, it can be seen that CR and ESR change depending on the type and amount of the highly conductive agent even in the case of a dispersion liquid irradiated with ultrasonic waves having a frequency of 2.4 MHz and an output of 7 W / cm ² for 5 minutes. A sorbitol rich dispersion led to a capacitor with higher CR and lower ESR.

(2) Solid Electrolytic Capacitor of Second Form Example 7
25 g of a mixed solution in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 2.0% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes, and further at a frequency of 2 Ultrasonic waves of 4 MHz and output of 7 W / cm ² were irradiated for 5 minutes. The viscosity of the liquid before addition of the highly conductive agent was 23.3 mPa · s. Next, 2.5 g of ethylene glycol as a highly conductive agent was added, and aqueous ammonia was added to adjust the pH to 8 to obtain a dispersion for forming a solid electrolyte layer.

  A capacitor element was obtained by winding an etched aluminum foil with a film withstand voltage of 130 V as an anode, and using the etched aluminum foil as a cathode, and winding them through a separator having a thickness of 50 μm. . A solid electrolyte layer containing PEDOT / PSS and ethylene glycol is formed between the oxide film of the anode and the cathode by repeating the process of immersing this capacitor element in the dispersion and drying it at 170 ° C. for 1 hour three times. did. Finally, the obtained element was inserted into a bottomed cylindrical aluminum case and sealed to obtain a solid electrolytic capacitor.

  About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 2.

Example 8
An ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² for 5 minutes, an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² for 5 minutes, and an ultrasonic wave with a frequency of 2.4 MHz and an output of 7 W / cm ² for 5 minutes. Instead of irradiating for 5 minutes, an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, and then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes. The procedure was repeated. The viscosity of the liquid before addition of the highly conductive agent was 24.6 mPa · s. Table 2 shows the capacity appearance rate at 120 Hz and the ESR at 100 kHz for the obtained solid electrolytic capacitor.

Example 9
An ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² for 5 minutes, an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² for 5 minutes, and an ultrasonic wave with a frequency of 2.4 MHz and an output of 7 W / cm ² for 5 minutes. Instead of irradiating for 5 minutes, an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² is applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² is applied for 5 minutes, and further a frequency of 2.4 MHz and an output of 7 W / cm. The procedure of Example 7 was repeated except that ² ultrasonic waves were irradiated for 10 minutes. The viscosity of the liquid before addition of the highly conductive agent was 22.2 mPa · s. Table 2 shows the capacity appearance rate at 120 Hz and the ESR at 100 kHz for the obtained solid electrolytic capacitor.

Example 10
An ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² for 5 minutes, an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² for 5 minutes, and an ultrasonic wave with a frequency of 2.4 MHz and an output of 7 W / cm ² for 5 minutes. Instead of irradiating for 5 minutes, an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² is applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² is applied for 10 minutes, and further, a frequency of 2.4 MHz and an output of 7 W / cm. The procedure of Example 7 was repeated except that ² ultrasonic waves were irradiated for 5 minutes. The viscosity of the liquid before the addition of the highly conductive agent was 24.3 mPa · s. Table 2 shows the capacity appearance rate at 120 Hz and the ESR at 100 kHz for the obtained solid electrolytic capacitor.

Example 11
An ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² for 5 minutes, an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² for 5 minutes, and an ultrasonic wave with a frequency of 2.4 MHz and an output of 7 W / cm ² for 5 minutes. Instead of irradiating for 5 minutes, an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² is applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² is applied for 10 minutes, and further, a frequency of 2.4 MHz and an output of 7 W / cm. The procedure of Example 7 was repeated except that ² ultrasonic waves were irradiated for 10 minutes. The viscosity of the liquid before addition of the highly conductive agent was 22.8 mPa · s. Table 2 shows the capacity appearance rate at 120 Hz and the ESR at 100 kHz for the obtained solid electrolytic capacitor.

Example 12
An ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² for 5 minutes, an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² for 5 minutes, and an ultrasonic wave with a frequency of 2.4 MHz and an output of 7 W / cm ² for 5 minutes. Instead of irradiating for 5 minutes, an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² is applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² is applied for 10 minutes, and further, a frequency of 2.4 MHz and an output of 7 W / cm. The procedure of Example 7 was repeated except that ² ultrasonic waves were irradiated for 30 minutes. The viscosity of the liquid before addition of the highly conductive agent was 22.3 mPa · s. Table 2 shows the capacity appearance rate at 120 Hz and the ESR at 100 kHz for the obtained solid electrolytic capacitor.

Example 13
An ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² for 5 minutes, an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² for 5 minutes, and an ultrasonic wave with a frequency of 2.4 MHz and an output of 7 W / cm ² for 5 minutes. Instead of irradiating for 5 minutes, an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² is applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² is applied for 10 minutes, and further, a frequency of 2.4 MHz and an output of 7 W / cm. The procedure of Example 7 was repeated, except that ² ultrasonic waves were irradiated for 60 minutes. The viscosity of the liquid before addition of the highly conductive agent was 20.5 mPa · s. Table 2 shows the capacity appearance rate at 120 Hz and the ESR at 100 kHz for the obtained solid electrolytic capacitor.

Example 14
25 g of a mixed solution in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 0.8% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes, and further at a frequency of 2 Ultrasonic waves of 4 MHz and output of 7 W / cm ² were irradiated for 5 minutes. Next, 1 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a highly conductive agent is added, and ammonia water is added to adjust the pH to 8 to prepare a dispersion for forming a solid electrolyte layer. Obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 130 V was obtained in the same manner as in Example 7. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 2.

Example 15
25 g of a mixed solution in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed in water at a concentration of 1.0% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes, and further at a frequency of 2 Ultrasonic waves of 4 MHz and output of 7 W / cm ² were irradiated for 5 minutes. Next, 1.25 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a highly conductive agent is added, pH is adjusted to 8 by adding ammonia water, and dispersion for forming a solid electrolyte layer A liquid was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 130 V was obtained in the same manner as in Example 7. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 2.

Example 16
25 g of a mixed solution was prepared in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 1.5% by mass. Next, the mixture was stirred with a stirring homogenizer, and then an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes, and further at a frequency of 2 Ultrasonic waves of 4 MHz and output of 7 W / cm ² were irradiated for 5 minutes. Next, 1.875 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a highly conductive agent is added, and the pH is adjusted to 8 by adding aqueous ammonia to form a dispersion for forming a solid electrolyte layer. A liquid was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 130 V was obtained in the same manner as in Example 7. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 2.

Example 17
25 g of a mixed solution in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 2.0% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes, and further at a frequency of 2 Ultrasonic waves of 4 MHz and output of 7 W / cm ² were irradiated for 5 minutes. Next, 2.5 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a highly conductive agent is added, and the pH is adjusted to 8 by adding aqueous ammonia to form a dispersion for forming a solid electrolyte layer. A liquid was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 130 V was obtained in the same manner as in Example 7. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 2.

Example 18
25 g of a mixed solution in which aggregates of PEDOT / PSS (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 2.5% by mass was prepared. Next, the mixture was stirred with a stirring homogenizer, and then an ultrasonic wave with a frequency of 20 kHz and an output of 50 W / cm ² was applied for 5 minutes, then an ultrasonic wave with a frequency of 1.6 MHz and an output of 20 W / cm ² was applied for 5 minutes, and further at a frequency of 2 Ultrasonic waves of 4 MHz and output of 7 W / cm ² were irradiated for 5 minutes. Next, 3.125 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a highly conductive agent is added, and aqueous pH is adjusted to 8 by adding aqueous ammonia to form a solid electrolyte layer. A liquid was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 130 V was obtained in the same manner as in Example 7. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 2.

Comparative Example 12
25 g of a mixed solution was prepared in which PEDOT / PSS aggregates (particle size: 300 nm to 1 μm: average particle size: 450 nm) obtained by chemical polymerization were mixed with water at a concentration of 1.5% by mass. Next, the mixture was stirred with a stirring homogenizer, and then irradiated with ultrasonic waves having a frequency of 20 kHz and an output of 50 W / cm ² for 5 minutes. Next, 1.875 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a highly conductive agent is added, and the pH is adjusted to 8 by adding aqueous ammonia to form a dispersion for forming a solid electrolyte layer. A liquid was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor provided with an anode having a film withstand voltage of 130 V was obtained in the same manner as in Example 7. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 2.

Comparative Example 13
A liquid mixture was prepared in which PEDOT / PSS (particle size; 300 nm to 1 μm: average particle size; 450 nm) obtained by chemical polymerization was mixed with water at a concentration of 0.5% by mass. Next, this mixed solution was stirred with a stirring homogenizer, and then passed through a high-pressure homogenizer (product name: Starburst Mini (manufactured by Sugino Machine Co., Ltd.)) 20 times under a condition of 200 MPa, thereby performing a high-pressure dispersion treatment. Furthermore, the obtained liquid was concentrated, and a liquid in which PEDOT / PSS was dispersed in water at a concentration of 1.5% by mass was obtained. Next, 1.875 g (PEDOT / PSS: sorbitol = 17: 83) of sorbitol as a highly conductive agent is added to 25 g of the obtained liquid, and the pH is adjusted to 8 by adding aqueous ammonia to obtain a solid electrolyte. A dispersion for forming a layer was obtained.

  Using the obtained dispersion, a solid electrolytic capacitor having an anode with a film withstand voltage of 130 V was obtained in the same manner as in Example 7. About the obtained solid electrolytic capacitor, the capacity appearance rate at 120 Hz and the ESR at 100 kHz were measured. The results are shown in Table 2.

  From a comparison between Example 16 (and Comparative Example 12) and Comparative Example 13, solid electrolytic using a dispersion liquid subjected to ultrasonic dispersion in the capacitor of the second form as well as the capacitor of the first form. It can be seen that the capacitor exhibits higher CR and lower ESR than the capacitor using the dispersion containing the same amount of PEDOT / PSS that has been subjected to dispersion treatment by a high-pressure homogenizer. Further, from the comparison between Example 16 and Comparative Example 12, when a dispersion liquid irradiated with ultrasonic waves having a frequency of 1.6 MHz and 2.4 MHz following irradiation of ultrasonic waves having a frequency of 20 kHz is used, It turns out that CR improves.

  From the comparison of Examples 14 to 18, the influence of the PEDOT / PSS content can be seen. The ESR of the obtained solid electrolytic capacitor decreases as the content of PEDOT / PSS in the dispersion increases, but for the CR of the capacitor, the content of PEDOT / PSS is 0.77% by mass (PEDOT / PSS in the mixed solution). The capacitor of Example 14 using the dispersion having a PSS content of 0.8% by mass had a PEDOT / PSS content of 0.95% by mass (the PEDOT / PSS content in the mixed solution was 1. The capacitor of Example 15 using a dispersion liquid of 0 mass%), the dispersion liquid having a PEDOT / PSS content of 1.40 mass% (the content of PEDOT / PSS in the mixed liquid is 1.50 mass%) The capacitor of Example 16 using PEDOT / PSS was 1.82% by mass (the content of PEDOT / PSS in the mixed solution was 2% by mass) The CR value is smaller than that of the capacitor of Example 17 using the dispersion liquid, and the content of PEDOT / PSS is 2.22% by mass (the content of PEDOT / PSS in the mixed solution is 2.5% by mass). The capacitor of Example 18 using the dispersion showed a CR value significantly lower than that of Example 17. This is considered to reflect the fact that the dispersibility of PEDOT / PSS is lowered even if the content in the dispersion of PEDOT / PSS is too low or too high.

  The effect of the content of the PEDOT / PSS dispersion in the capacitor of the second form is greater than that of the capacitor of the first form (see Examples 1, 3 and 4). Then, the dispersion liquid penetrates into the anode oxide film relatively easily, whereas in the capacitor of the second form, before the dispersion liquid penetrates into the anode oxide film, the periphery of the capacitor element, the anode and the cathode If the dispersibility of PEDOT / PSS is good, it is considered that the greater the content, the easier and quicker the penetration into the oxide film.

  Comparison of Examples 7 to 13 shows the influence of the frequency of the ultrasonic wave on the dispersibility of PEDOT / PSS. From the comparison between Example 7 and Example 8, irradiation with ultrasonic waves having a frequency of 20 MHz, irradiation with ultrasonic waves having a frequency of 1.6 MHz, followed by irradiation with ultrasonic waves having a frequency of 2.4 MHz, It can be seen that the CR of the capacitor is further improved. Further, as can be seen from the comparison between Example 7 and Example 10, in the irradiation with ultrasonic waves having a frequency of 1.6 MHz, the improvement of the CR of the capacitor was no longer observed after irradiation for 5 minutes or more. As can be seen from the comparison of ˜13, in the ultrasonic irradiation with the frequency of 2.4 MHz, the longer the ultrasonic irradiation time, the slightly lower the viscosity of the dispersion and the CR of the capacitor was improved.

  About the solid electrolytic capacitor of Example 7 and Example 17, the current-voltage curve was obtained and the withstand voltage property was evaluated by the voltage value at which the failure occurred. Table 3 shows the results.

  The capacitor of Example 17 containing sorbitol as a high conductivity agent in the solid electrolyte layer was significantly increased compared to the capacitor of Example 7 containing ethylene glycol as the high conductivity agent in the solid electrolyte layer. It turns out that it has withstand voltage property. In addition, when the withstand voltage property of the solid electrolytic capacitor using the dispersion liquid containing no high conductivity agent was also evaluated, it was 60V.

  A solid electrolytic capacitor having a high CR and a low ESR can be suitably used for a wide range of applications, and the dispersion of the present invention allows a solid electrolytic capacitor having such a high CR and a low ESR to be easily and quickly. Can be obtained.

Claims (14)

A method for producing a dispersion for a solid electrolytic capacitor comprising water as a dispersion medium and fine particles of a water-insoluble or poorly water-soluble conductive polymer derived from a monomer having a π-conjugated double bond,
A preparation step of obtaining a mixed solution containing water and fine particles of the conductive polymer; and
A dispersion step of irradiating the mixed liquid with ultrasonic waves having a frequency of 15 to 100 kHz and further irradiating ultrasonic waves having a frequency of 0.8 to 4 MHz; Production method.   The method for producing a dispersion for a solid electrolytic capacitor according to claim 1, wherein the conductive polymer contains a polymer anion as a dopant.   The method for producing a dispersion for a solid electrolytic capacitor according to claim 1 or 2, wherein the monomer is at least one compound selected from the group consisting of thiophenes having substituents at the 3-position and the 4-position.   The method for producing a dispersion for a solid electrolytic capacitor according to claim 2 or 3, wherein the monomer is 3,4-ethylenedioxythiophene and the polymer anion is a polystyrene sulfonate anion.   The said dispersion | distribution process WHEREIN: The irradiation of the ultrasonic wave which has a frequency of 0.8-4 MHz is performed 2 times or more, increasing the frequency of an ultrasonic wave as the frequency | count increases. The manufacturing method of the dispersion liquid for solid electrolytic capacitors of description.   In the dispersion step, a water-soluble compound having a hydroxy group, a water-soluble compound having an amide group, a water-soluble compound having a lactone group, a water-soluble compound having a lactam group, and an ether group are added to the dispersion after ultrasonic irradiation. The dispersion for a solid electrolytic capacitor according to any one of claims 1 to 5, wherein at least one compound selected from the group consisting of a water-soluble compound having water, a water-soluble sulfoxide and a water-soluble sulfone is added as a highly conductive agent. Liquid manufacturing method.   The method for producing a dispersion for a solid electrolytic capacitor according to claim 6, wherein the water-soluble compound having a hydroxy group is sorbitol.   The manufacturing method of the dispersion liquid for solid electrolytic capacitors of any one of Claims 1-7 which adjusts the pH of the said dispersion liquid in the range of 4-10 in the said dispersion | distribution process.   The manufacturing method of the dispersion liquid for solid electrolytic capacitors of any one of Claims 1-8 whose content of the said conductive polymer in the said liquid mixture is the range of 1.0-2.0 mass%.   A water-insoluble or difficult water derived from water as a dispersion medium and a monomer having a π-conjugated double bond obtained by the method for producing a dispersion for a solid electrolytic capacitor according to any one of claims 1 to 9. A dispersion for a solid electrolytic capacitor comprising fine particles of a soluble conductive polymer. Solid electrolysis comprising an anode made of a valve metal foil having an oxide film on the surface, and a water-insoluble or poorly water-soluble conductive polymer derived from a monomer having a π-conjugated double bond provided on the oxide film of the anode A method for producing a solid electrolytic capacitor comprising a layer,
The solid electrolyte which forms the solid electrolyte layer containing the said conductive polymer on the oxide film of the said anode by making the dispersion liquid for solid electrolytic capacitors of Claim 10 infiltrate into the oxide film of the said anode, and drying. A method for producing a solid electrolytic capacitor comprising a layer forming step. A water-insoluble material derived from a monomer having a π-conjugated double bond disposed between an anode made of a valve metal foil having an oxide film on its surface, a cathode made of a valve metal foil, and the anode and the cathode. A separator holding a solid electrolyte layer containing a poorly water-soluble conductive polymer, and a method for producing a solid electrolytic capacitor comprising:
An element creation step for obtaining a capacitor element including the anode, the cathode, and a separator disposed between the anode and the cathode; and
A solid electrolyte layer containing the conductive polymer is formed between the oxide film of the anode and the cathode by impregnating the capacitor element with the dispersion for a solid electrolytic capacitor according to claim 10 and drying the dispersion. A solid electrolyte layer forming step of manufacturing a solid electrolytic capacitor.   An anode comprising a valve metal foil having an oxide film on the surface thereof obtained by the method for producing a solid electrolytic capacitor according to claim 11, and a monomer having a π-conjugated double bond provided on the oxide film of the anode. And a solid electrolyte layer containing an induced water-insoluble or poorly water-soluble conductive polymer.   An anode made of a valve metal foil having an oxide film on its surface, a cathode made of a valve metal foil, and a cathode made of a valve metal foil, obtained by the method for producing a solid electrolytic capacitor according to claim 12, and disposed between the anode and the cathode. And a separator holding a solid electrolyte layer containing a water-insoluble or poorly water-soluble conductive polymer derived from a monomer having a π-conjugated double bond.