JP2010090324A - Dopant solution for conductive polymer, dopant solution also serving as oxidizer for conductive polymer, conductive composition, solid electrolytic capacitor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxidizing agent / dopant solution for providing a conductive composition having high conductivity with high reaction efficiency, a dopant solution for constituting the oxidizing agent / dopant solution, the conductive composition having high conductivity, and To provide a solid electrolytic capacitor with high long-term reliability.
SOLUTION: At least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups is contained at a concentration of 40% by mass or more. A conductive polymer dopant solution, and a mixture of the salt and persulfuric acid organic salt to form a conductive polymer oxidant / dopant solution, and the oxidant / dopant solution is used to form a conductive composition. A solid electrolytic capacitor is constructed using the conductive composition as a solid electrolyte.
[Selection figure] None

Description

  The present invention provides a conductive polymer dopant solution, an oxidizing agent / dopant solution containing the dopant and an oxidizing agent, a conductive composition containing a conductive polymer synthesized using the oxidizing agent / dopant solution, The present invention relates to a solid electrolytic capacitor using a conductive composition as a solid electrolyte and a method for manufacturing the same.

  Solid electrolytic capacitors using conductive polymer as solid electrolyte have various characteristics such as low ESR (equivalent series resistance) and high reliability compared to conventional solid electrolytic capacitors using manganese dioxide as solid electrolyte. The market is expanding at a rapid pace.

  The conductive polymer is generally produced by a chemical oxidative polymerization method. For example, a transition metal salt of an organic sulfonic acid such as iron paratoluenesulfonate is used as an oxidizing agent and a dopant, and thiophene or a derivative thereof. It is performed by polymerizing the monomer (patent documents 1 and 2).

  However, although these methods are suitable for mass production, there is a problem that the transition metal used as the oxidizing agent remains in the conductive polymer. Therefore, even if a washing process is performed to remove the transition metal, the transition metal has a property that it is difficult to remove completely, and it is given to the conductive polymer of the transition metal when the transition metal remains in the conductive polymer. There has been a demand for further improving the stability of the conductive polymer and the long-term reliability of the solid electrolytic capacitor by wiping out the influence and the influence on the solid electrolytic capacitor using it as a solid electrolyte. Therefore, it has been proposed to use a peroxide other than a transition metal salt as an oxidizing agent, for example, peroxide as an oxidizing agent. However, when thiophene or a derivative thereof is used as a monomer, the reaction efficiency is higher than that of a transition metal salt. There is a problem that the conductivity of the obtained conductive polymer is very bad.

  Therefore, it has been proposed to improve the reaction efficiency by using, as a dopant, an alkylamine salt or imidazole salt of a benzene skeleton sulfonic acid or naphthalene skeleton sulfonic acid containing an OH group (Patent Document 3).

  According to the above method, the reaction efficiency at the time of synthesizing the conductive polymer is improved and the conductivity of the obtained conductive polymer is improved as compared with the previous technique, but it is still not sufficient. .

Japanese Patent Laid-Open No. 10-50558 JP 2000-106331 A WO2006-085601

  The present invention solves the problems of the prior art as described above, and constitutes an oxidizing agent / dopant solution capable of providing a conductive composition having high conductivity with high reaction efficiency, and the oxidizing agent / dopant solution. And a conductive composition containing a conductive polymer with high conductivity by using the oxidant / dopant solution, and using the conductive composition as a solid electrolyte for a long time. An object is to provide a solid electrolytic capacitor with high reliability.

  As a result of intensive studies to solve the above problems, the present inventor has selected from benzene skeleton sulfonic acid having two or more sulfone groups or alkylamine salt or imidazole salt of naphthalene skeleton sulfonic acid having three or more sulfone groups. A heterocyclic structure such as thiophene or a derivative thereof, pyrrole or a derivative thereof, aniline or a derivative thereof, using at least one selected from the group consisting of a dopant and a mixture of an organic salt and a persulfate organic salt constituting the dopant as an oxidizing agent and a dopant. When the monomer is polymerized, a conductive composition containing a conductive polymer with high conductivity can be obtained with high reaction efficiency, and long-term reliability is high by using the conductive composition as a solid electrolyte. A solid electrolytic capacitor can be constructed and the above problems can be solved. It was.

  That is, in the present invention, at least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups has a concentration of 40% by mass or more. The present invention relates to a conductive polymer dopant solution characterized by being dissolved.

  The present invention also relates to an oxidizing agent and dopant which is a mixture of a benzene sulfonic acid having two or more sulfonic groups or an alkylamine salt or imidazole salt of a naphthalene sulfonic acid having three or more sulfonic groups and a persulfuric acid organic salt. And at least one selected from alkylamine salts or imidazole salts of benzene skeleton sulfonic acid having two or more sulfone groups or naphthalene skeleton sulfonic acid having three or more sulfone groups by mass ratio: 1 On the other hand, it is related with the oxidizing agent and dopant solution for conductive polymers characterized by being persulfuric acid organic salt: 0.1-1.5.

  Furthermore, the present invention provides a mixture of a persulfuric acid organic salt and at least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups. Is an electroconductive composition obtained by polymerizing at least one selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof, and aniline or a derivative thereof.

  In addition, the present invention provides a persulfuric acid organic salt and at least one selected from a benzene skeleton sulfonic acid having two or more sulfonic groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfonic groups. Using the mixture as an oxidizing agent / dopant, a conductive composition obtained by polymerizing at least one selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof and aniline or a derivative thereof was used as a solid electrolyte. Further, the present invention is selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof, and aniline or a derivative thereof in the presence of the above oxidizing agent / dopant solution. Obtained by polymerizing at least one of A manufacturing method of a solid electrolytic capacitor, characterized in that configured using the conductive composition as a solid electrolyte.

  The conductive composition of the present invention is a thiophene or derivative thereof whose main component is oxidatively polymerized by the oxidizing action of the oxidant part of the specific oxidant / dopant, and has conductivity by incorporating the dopant. It is composed of a polymer (polymer) of at least one monomer selected from the group consisting of pyrrole or a derivative thereof and aniline or a derivative thereof, but in the present invention, it is not a conductive polymer but a conductive composition. Because the oxidizing agent / dopant does not contain a metal salt, thiophene or a derivative thereof, pyrrole or a derivative thereof polymerized by incorporating the dopant, even though some unreacted components or reaction residues are contained. It has an adverse effect on the polymer of at least one monomer selected from the group consisting of aniline or its derivatives. It has almost the same characteristics as the conductive polymer without spilling, and can be used for almost the same applications as the conductive polymer. Therefore, they can be purified without removing unreacted components and reaction residues. It may mean that it may be configured as it is included. That is, the conductive composition of the present invention is selected from the group consisting of a conductive polymer as a main component (thiophene or a derivative thereof, pyrrole or a derivative thereof, and aniline or a derivative thereof polymerized by incorporating the above-mentioned specific dopant). It is a concept that includes not only those composed only of a polymer of at least one kind of monomer), but also those composed of some of the above-mentioned unreacted components and reaction residues together with the conductive polymer.

  According to the present invention, it is possible to provide a conductive composition having high conductivity with high reaction efficiency, and to provide a solid electrolytic capacitor with high long-term reliability using the conductive composition as a solid electrolyte. Can do. Moreover, according to the oxidizing agent and dopant solution of the present invention, the conductive composition of the present invention can be provided with high reaction efficiency. According to the dopant solution of the present invention, the oxidizing agent and dopant of the present invention. A solution can be constructed.

  That is, in the present invention, in obtaining a conductive composition, a mixture of an alkylamine salt or imidazole salt of a specific organic sulfonic acid and a persulfuric acid organic salt is used as the oxidizing agent and dopant. Does not contain a metal salt causing acceleration of the deterioration of the conductive polymer, and the solubility of the oxidizing agent / dopant used is high, and thiophene or its derivative, pyrrole or its compound is present in the presence of a high concentration of oxidizing agent / dopant. Since at least one monomer selected from the group consisting of a derivative and aniline or a derivative thereof can be polymerized, the monomers can be efficiently polymerized, and thus a highly conductive composition having high conductivity can be obtained. It can be provided with reaction efficiency. In addition, since the conductive composition of the present invention has high conductivity and little decrease in conductivity due to storage, a solid electrolytic capacitor having higher long-term reliability than before can be obtained by using the conductive composition as a solid electrolyte. Can be provided.

  Since the conductive composition of the present invention has high conductivity and does not contain a metal salt, it does not cause rapid deterioration due to the metal salt as found in conventional conductive compositions. It is used for the solid electrolyte of capacitors, but in addition to these characteristics, it can be used for antistatic agents such as antistatic sheets, antistatic paints, antistatic resins, and anticorrosives for anticorrosion paints. It can be used suitably.

  The dopant solution for a conductive polymer of the present invention is for constituting the oxidant / dopant solution for a conductive polymer of the present invention, and as its component, a benzene skeleton sulfonic acid having two or more sulfone groups or At least one selected from alkylamine salts or imidazole salts of naphthalene skeleton sulfonic acid having 3 or more sulfone groups is used.

  A benzene skeleton sulfonic acid having two or more sulfone groups or a naphthalene skeleton sulfonic acid having three or more sulfone groups has no hydroxyl group (OH group) bonded to the benzene nucleus or naphthalene nucleus. Examples of the benzene skeleton sulfonic acid having 2 or more include 1,2-benzenedisulfonic acid, 1,3-benzenedisulfonic acid, 1,4-benzenedisulfonic acid, 1,3,5-benzenetrisulfonic acid, and the like. Examples of the naphthalene skeleton sulfonic acid having three or more sulfone groups include 1,3,6-naphthalene trisulfonic acid, 1,3,8-naphthalene trisulfonic acid, and 1,4,8-naphthalene. And trisulfonic acid. And as an alkylamine which comprises the alkylamine salt of the benzene skeleton sulfonic acid or naphthalene skeleton sulfonic acid, what has a C1-C12 alkyl group is preferable, As a suitable specific example, for example, methyl Examples include amine, ethylamine, propylamine, butylamine, octylamine, dodecylamine, 3-ethoxypropylamine, and 3- (2-ethylhexyloxy) propylamine.

  In addition, as imidazole constituting the imidazole salt of benzene skeleton sulfonic acid having two or more sulfone groups or naphthalene skeleton sulfonic acid having three or more sulfone groups, imidazole itself or a part of hydrogen atoms on the imidazole ring is carbon Those substituted with an alkyl group of 1 to 20 or a phenyl group are preferred. That is, the “benzene skeleton sulfonic acid having two or more sulfone groups or the imidazole salt of naphthalene skeleton sulfonic acid having three or more sulfone groups” as used in the present invention refers to a benzene skeleton sulfonic acid or sulfone having two or more sulfone groups. Not only a salt composed of naphthalene skeleton sulfonic acid having three or more groups and imidazole, but also benzene skeleton sulfonic acid having two or more sulfonic groups or naphthalene skeleton sulfonic acid having three or more sulfonic groups and imidazole derivatives (for example, It is a concept including a salt composed of an imidazole derivative in which a part of hydrogen atoms on the imidazole ring is substituted with an alkyl group or a phenyl group.

  In addition, when the imidazole constituting the imidazole salt of the benzene skeleton sulfonic acid or naphthalene skeleton sulfonic acid is substituted with an alkyl group having 1 to 20 carbon atoms or a phenyl group, it can be manufactured at low cost and has good productivity. In this respect, it is preferable that the 2-position or 4-position of the imidazole ring is substituted.

  Preferable specific examples of the imidazole constituting the imidazole salt of a benzene skeleton sulfonic acid having two or more sulfone groups or a naphthalene skeleton sulfonic acid having three or more sulfone groups include, for example, imidazole, 1-methylimidazole, 2-methyl Imidazole, 2-ethylimidazole, 2-butylimidazole, 2-undecylimidazole, 2-phenylimidazole, 4-methylimidazole, 4-undecylimidazole, 4-phenylimidazole, 2-ethyl-4-methylimidazole, 1, Examples include 2-dimethylimidazole, and imidazole, 2-methylimidazole, and 4-methylimidazole are particularly preferable.

  The solvent for the dopant solution is usually water, but may be an aqueous solution containing about 50% by volume or less of a water-compatible organic solvent such as ethanol.

  The concentration in the dopant solution of at least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups is 40% by mass or more. It is preferable that it is 70 mass% or more. Such a high-concentration dopant solution can constitute a high-concentration oxidant / dopant solution (described in detail later) that can produce the conductive composition having excellent conductivity with high reaction efficiency. In addition, the upper limit of the concentration in the dopant solution of at least one selected from benzene sulfonic acid having two or more sulfone groups or alkylamine salt or imidazole salt of naphthalene skeleton sulfonic acid having three or more sulfone groups is, for example, 95% by mass is preferable.

  The pH of the dopant solution is preferably 1 or more, and more preferably 4 or more. When producing a conductive composition for use in an aluminum solid electrolytic capacitor, it is preferable to set the pH of the oxidizer / dopant solution to 1 or higher to suppress the breakdown of the dielectric layer of the capacitor element related to the aluminum solid electrolytic capacitor. However, by setting the pH of the dopant solution to 1 or more (details will be described later), it becomes possible to easily provide an oxidizing agent / dopant solution suitable for the production of a conductive composition for an aluminum solid electrolytic capacitor. And the pH of this dopant solution is preferably 10 or less, and more preferably 8 or less.

  Moreover, it is preferable to add an emulsifier to the dopant solution. This is because, by adding an emulsifier, at least one polymerization reaction selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof, and aniline or a derivative thereof can proceed more uniformly. It is because a dopant solution can be comprised. Various emulsifiers can be used, and alkylamine oxide is particularly preferable. Even when the alkylamine oxide remains in the conductive composition, the conductivity of the conductive composition is greatly reduced, or when the conductive composition is used as a solid electrolyte of a solid electrolytic capacitor, There is no significant deterioration in the function of the capacitor. The alkyl group in the alkylamine oxide preferably has 1 to 20 carbon atoms. Further, when the polymerization reaction of the monomer proceeds, the pH of the reaction system decreases accordingly, and the alkylamine oxide also has an action of suppressing such a decrease in pH.

  The oxidant / dopant solution for a conductive polymer of the present invention is at least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups. An oxidizer / dopant which is a mixture of a seed and a persulfate organic salt is dissolved.

  The alkylamine salt or imidazole salt of a benzene skeleton sulfonic acid having two or more sulfone groups or a naphthalene skeleton sulfonic acid having three or more sulfone groups, or a solvent in the oxidant / dopant solution is the same as the dopant solution. Applicable.

  Examples of the persulfuric acid organic salt relating to the oxidant / dopant solution include ammonium persulfate, persulfuric acid alkylamine salts, and persulfate imidazole salts. And about the alkylamine salt and imidazole salt, the thing similar to what was demonstrated regarding the alkylamine salt and imidazole salt of the said specific benzene frame | skeleton sulfonic acid or naphthalene frame | skeleton sulfonic acid is preferable.

  A persulfuric acid organic salt and at least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups in the oxidant / dopant solution. As a mixing ratio, at least one selected from a mass ratio of a benzene skeleton sulfonic acid having two or more sulfonic groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfonic groups, Persulfate organic salt: 0.1 or more, preferably 0.2 or more, and 1.5 or less, preferably 0.8 or less. When the mixing ratio of the persulfuric acid organic salt is higher than the above ratio, the ratio of the alkylamine salt or imidazole salt of the specific organic sulfonic acid decreases, so that sulfate ions increase as a dopant, resulting in the resulting conductivity. The electrical conductivity of the conductive composition tends to decrease and the heat resistance tends to deteriorate. Moreover, when the mixing ratio of the persulfuric acid organic salt is less than the above ratio, it tends to be difficult to obtain a polymer.

  In the present invention, the alkylamine salt or imidazole salt of organic sulfonic acid in a mixture of at least one selected from the alkylamine salt or imidazole salt of the above-mentioned specific organic sulfonic acid used as an oxidant and dopant is persulfuric acid organic salt. , Mainly plays a role as a dopant, and persulfate organic salt mainly plays a role as an oxidant, but both organic sulfonic acid and persulfate organic salt in them use organic salt, Since they are not included, rapid deterioration of the conductive polymer due to the metal salt as found in conventional conductive polymers does not occur. In addition, the benzene skeleton sulfonic acid having two or more sulfonic groups or the naphthalene skeleton sulfonic acid having three or more sulfonic acids as the organic sulfonic acid is a requirement for at least one sulfonic group to function as a dopant. This is because other sulfone groups are necessary to promote the polymerization reaction. Furthermore, the presence of many sulfone groups enhances the electron-withdrawing property, and thereby the conductive composition. It is because it is thought that the electrical conductivity of this improves. The reason why the sulfone group has such an effect is not necessarily clear at present, but it is thought that the proton of the sulfone group may cause the polymerization reaction to proceed rapidly and be easily incorporated into the polymer as a dopant. It is done. In addition, it is considered that a high concentration, which is a necessary requirement of the present invention, has become possible by including a plurality of sulfone groups that enhance water solubility. Furthermore, the sulfonic acid has the benzene skeleton or the naphthalene skeleton because the organic sulfonic acid has a benzene skeleton or a naphthalene skeleton, whereby the heat resistance of the obtained conductive composition can be improved. .

  The oxidizing agent / dopant solution of the present invention includes, for example, naphthalene trisulfonic acid as a naphthalene skeleton sulfonic acid having three or more sulfone groups, butylamine as an alkylamine, and ammonium persulfate as a persulfate organic salt. Can be obtained as follows, for example. First, by adding butylamine to an aqueous solution of naphthalenetrisulfonic acid and adjusting the pH, an aqueous solution of butylamine naphthalenetrisulfonate (that is, the dopant solution for conductive polymer of the present invention) can be obtained. And, for example, by mixing a solution obtained by separately dissolving solid ammonium persulfate in water and the above aqueous solution of butylamine naphthalene trisulfonate (a dopant solution for a conductive polymer of the present invention), the oxidizing agent and dopant of the present invention A solution can be obtained.

  In the conductive composition of the present invention, at least one selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof and aniline or a derivative thereof is used as a monomer. Examples of the thiophene derivative include 3, Examples include 4-ethylenedioxythiophene, 3-alkylthiophene, 3-alkoxythiophene, 3-alkyl-4-alkoxythiophene, 3,4-alkylthiophene, 3,4-alkoxythiophene, and the like. For example, 3,4-alkyl pyrrole, 3,4-alkoxy pyrrole and the like can be mentioned. Examples of aniline derivatives include 2-alkyl aniline, 2-alkoxy aniline and the like. The alkyl group or alkoxy group preferably has 1 to 16 carbon atoms.

  In the polymerization of the monomer, a liquid one can be used as it is. However, in order to make the polymerization reaction proceed more smoothly, the monomer may be used with an organic solvent such as methanol, ethanol, propanol, butanol, acetone, or acetonitrile. It is preferable to dilute it into a solution (organic solvent solution).

  As an aspect at the time of polymerization of the above-mentioned monomer, it is preferable to adopt a different aspect depending on the usage form of the conductive composition. For example, the conductive composition is formed into a film or the like and applied to the application apparatus of the conductive composition. When the conductive composition is used as a solid electrolyte of a solid electrolytic capacitor, it can be used in the presence of an oxidizing agent / dopant solution during the production process of the solid electrolytic capacitor. It is preferable to polymerize the monomer.

  As the polymerization mode of the monomer derivative, for example, (1) at least selected from benzene skeleton sulfonic acid having two or more sulfone groups or alkylamine salt or imidazole salt of naphthalene skeleton sulfonic acid having three or more sulfone groups A method of polymerizing the monomer by mixing a solution of an oxidizing agent / dopant comprising a mixture of one kind and a persulfuric acid organic salt with the monomer or an organic solvent solution thereof; The capacitor element is soaked in the fine holes of the capacitor element, and the capacitor element is immersed in an oxidant / dopant solution to polymerize the monomer, or vice versa. After soaking into the fine holes of the capacitor element, Monomer or is dipped in the organic solvent solution, a method of polymerizing the monomers, and the like. Furthermore, the monomer may be polymerized by alternately immersing the capacitor element in an oxidizer / dopant solution and the monomer or an organic solvent solution thereof. At this time, the capacitor element may be immersed in any one of the oxidizing agent / dopant solution, the monomer or the organic solvent solution thereof.

Next, these polymerization modes (1) to (2) will be described more specifically.
Polymerization mode (1)
Alkylamine oxide is used as an emulsifier (specifically, for example, a 35% by mass decyldimethylamine oxide aqueous solution is used), and this emulsifier is used in a mass ratio with respect to the oxidant / dopant solution. 100: 20 to 100: 0.01, preferably 100: 10 to 10: 0.05, and the above monomer is 2 to 50%, preferably 10 to 30%, based on the weight of the solution. Mix together. After mixing for 30 seconds to 30 minutes, preferably 3 minutes to 20 minutes, the capacitor element is immersed in the mixture. After 10 seconds to 300 seconds, preferably after 30 seconds to 120 seconds, the capacitor element is pulled out from the liquid, left at a temperature of 0 to 50 ° C., preferably 5 to 30 ° C. for 30 minutes to 600 minutes, or pulled out. Immediately thereafter, the monomer is polymerized at a temperature of 50 ° C. to 200 ° C. for 10 minutes to 1 day.

Polymerization mode (2)
The tantalum sintered body is immersed in a solution (organic solvent solution) diluted with an organic solvent so that the concentration of the monomer is 5 to 100% by mass, more preferably 10 to 40% by mass, and more preferably 10 to 300s. After 20 seconds to 120 seconds, the tantalum sintered body is pulled out from the organic solvent solution of the monomer solution, and the solvent is evaporated to some extent at a temperature of 10 to 60 ° C., more preferably 10 to 30 ° C. More preferably, it is left for 1 to 10 minutes. Thereafter, an oxidizer / dopant solution prepared in advance and a 20% decyldimethylamine oxide solution as an emulsifier in a mass ratio of 100: 10 to 100: 0.01, preferably 100: 5 to 100: 0.1. The tantalum sintered body is immersed in the mixed liquid mixed in step 10 to 300 seconds, and after 10 to 60 seconds, the tantalum sintered body is taken out from the mixed liquid, and is heated at 0 to 50 ° C. and 10 to 30 ° C. After standing at the temperature until the surface is dry (more than 5 minutes) or immediately after dropping the organic solvent solution of the above monomer at a temperature of 0 to 120 ° C., preferably 30 to 70 ° C., preferably 10 minutes to 1 day, Is allowed to stand for 10 minutes to 2 hours to polymerize the monomer.

  The conductive composition of the present invention obtained by using the oxidizing agent / dopant solution of the present invention includes, for example, a tantalum solid electrolytic capacitor, a niobium solid electrolytic capacitor, an aluminum solid electrolytic capacitor (aluminum laminated solid electrolytic capacitor, aluminum winding). However, when the conductive composition of the present invention is used as a solid electrolyte of a solid electrolytic capacitor, as described above, the production process of the solid electrolytic capacitor Among these, it is preferable to perform polymerization of the above monomer. At that time, the concentration of the oxidizing agent / dopant solution affects the production efficiency of the conductive composition, that is, the reaction efficiency at the time of polymerization of the monomer, and thus affects the production efficiency and characteristics of the solid electrolytic capacitor. Therefore, the oxidant and dopant concentration in the oxidant and dopant solution is preferably 25% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, and further preferably 55% by mass or more. In any case, the concentration is preferably 80% by mass or less.

  That is, when the concentration of the oxidizing agent / dopant is lower than 25% by mass, the polymerization reaction of the monomer is difficult to proceed and the reaction efficiency is very poor, but at 25% by mass or more, the polymerization reaction is likely to proceed. When it is 30% by mass or more, more preferably 40% by mass or more, satisfactory results can be obtained in terms of manufacturing efficiency and characteristics of tantalum solid electrolytic capacitors, niobium solid electrolytic capacitors, aluminum solid electrolytic capacitors, and the like. However, by setting the concentration of the oxidizing agent / dopant solution to 55% by mass or more, a capacitor that is satisfactory in terms of characteristics such as low ESR and high capacitance can be obtained. However, when the concentration of the oxidizing agent / dopant solution is higher than 80% by mass, the characteristics tend to be deteriorated. The oxidizing agent / dopant solution of the present invention can have a high concentration as described above, which improves the production efficiency of the conductive composition, and thus the production efficiency and characteristics of the solid electrolytic capacitor.

  The pH of the oxidant / dopant solution is also particularly important for aluminum solid electrolytic capacitors, and if the pH is less than 1, the dielectric layer may be destroyed and excellent characteristics may not be obtained. The pH of the dopant solution is preferably 1 or more, more preferably 4 or more, preferably 10 or less, and more preferably 8 or less. However, a tantalum solid electrolytic capacitor, a niobium solid electrolytic capacitor, or the like may have a pH of less than 1 because the dielectric layer has high acid resistance. Incidentally, in the case of the organic sulfonic acid iron salt that has been used in the manufacture of the conventional solid electrolytic capacitor, the pH is about 0.5, which is not necessarily suitable for the manufacture of the aluminum solid electrolytic capacitor.

  As the polymerization reaction of the monomer derivative proceeds, the pH of the reaction system decreases, but when the above-mentioned alkylamine oxide is added as an emulsifier of the dopant solution to the oxidizing agent / dopant solution (for example, containing this emulsifier) In addition to the action that the alkylamine oxide suppresses the decrease in pH and makes the reaction progress uniformly, this effect is also effective in this aspect. .

  As described above, the concentration of the oxidant / dopant solution has been particularly described in the case of producing a solid electrolytic capacitor. However, the concentration of the oxidant / dopant solution is also important in producing a conductive composition. The concentration of the oxidant and dopant in the cum dopant solution is preferably 25% by mass or more, more preferably 30% by mass or more, further preferably 55% by mass or more, and preferably 80% by mass or less. In the production of the solid electrolytic capacitor, as described above, not only when the monomer is polymerized in the presence of the oxidant / dopant solution, but also once the oxidant / dopant solution is dried, The monomer may be contacted to polymerize the monomer. Further, also in the case of once drying and bringing into contact with the above monomer, the concentration of the oxidizing agent / dopant solution is preferably as high as possible, and the concentration is preferably 25% by mass or more as described above, and preferably 30% by mass or more. Is more preferable, 55 mass% or more is further more preferable, and 80 mass% or less is preferable.

The solid electrolytic capacitor of the present invention only needs to have the conductive composition of the present invention as a solid electrolyte, and the other configurations are the same as the configurations employed in conventionally known solid electrolytic capacitors. Things can be adopted.

  In the solid electrolytic capacitor of the present invention, at least one monomer selected from the group consisting of conductive polymer dopants and constituent monomers (thiophene or derivatives, pyrrole or derivatives thereof, and aniline or derivatives thereof) used as solid electrolytes ) With a molar ratio of 1: 1 to 1: 3.

  Systhetic Metals, 101 561-564 (1999), K.A. E. According to Aasmundtveut, when conducting polymer obtained by polymerizing 3,4-ethylenedioxythiophene using ferric (III) paratoluenesulfonate as an oxidant and dopant, washing and drying, the polymer is analyzed. The ratio of S (sulfur) of paratoluenesulfonic acid as a dopant to S (sulfur) of 3,4-ethylenedioxythiophene as a constituent monomer is 1: 4 in molar ratio regardless of the charged ratio. It is reported that it becomes. That is, the molar ratio of dopant: constitutive monomer is 1: 4.

  On the other hand, in the solid electrolytic capacitor of the present invention, for example, as shown in Examples 11 to 12 described later, the ratio of the dopant S (sulfur) to the constituent monomer S (sulfur) is 1 in molar ratio. : 1 to 1: 3. And it is thought that it can contribute to improving the electrical conductivity of the conductive polymer obtained also that the ratio of the dopant with respect to this structural monomer can be made high. That is, when the oxidizing agent / dopant of the present invention is used, the ratio of the conductive polymer dopant to the monomer of the obtained conductive polymer is higher than that of the case where para-toluenesulfonic acid ferric (III) is used as the oxidizing agent / dopant. This can be increased, and it is considered that this contributes to increasing the conductivity of the resulting conductive polymer.

  Next, the present invention will be described more specifically with reference to examples. However, this invention is not limited only to those Examples. In the following examples and the like,% indicating the concentration of a solution, a diluent, a dispersion, etc. is mass% unless otherwise indicated.

[Evaluation with conductive composition]
Example 1
Naphthalene trisulfonic acid with a concentration of 70% (all naphthalene trisulfonic acids used in the examples are 1,3,6-naphthalene trisulfonic acid) 3.58 ml of butylamine aqueous solution (pH 5) and ammonium persulfate with a concentration of 45% After 3.58 ml of the aqueous solution was put into a vial with a tight stopper and mixed, 150 μl of the mixed solution was dropped on a 3 cm × 4 cm ceramic plate and left at room temperature for 30 minutes. Next, 100 μl of an ethanol solution of 3,4-ethylenedioxythiophene having a concentration of 25% was dropped thereon, and left at room temperature for 5 minutes, and then a polymerization reaction was performed at 70 ° C. for 30 minutes. The polyethylene dioxythiophene formed on the ceramic plate was washed with a large excess of water and then dried at 50 ° C. for 1 hour and 150 ° C. for 1 hour to obtain a conductive composition. The ratio of butylamine naphthalene trisulfonate to ammonium persulfate in the mixed solution of butylamine naphthalene trisulfonate aqueous solution and ammonium persulfate aqueous solution is 0.64 ammonium persulfate with respect to butylamine naphthalene trisulfonate 1 in mass ratio. there were.

Example 2
Conductivity is the same as in Example 1 except that a 45% naphthalene trisulfonic acid butylamine aqueous solution (pH 5) is used instead of the 70% naphthalene trisulfonic acid butylamine aqueous solution (pH 5). A composition was obtained. The ratio of butylamine naphthalene trisulfonate to ammonium persulfate in the mixed solution of butylamine naphthalene trisulfonate aqueous solution and ammonium persulfate aqueous solution was ammonium persulfate 1 to butylamine naphthalene trisulfonate 1 in mass ratio. .

Example 3
The same operation as in Example 1 was performed except that a 70% naphthalene trisulfonic acid 2-methylimidazole aqueous solution (pH 5) was used instead of the 70% naphthalene trisulfonic acid butylamine aqueous solution (pH 5). As a result, a conductive composition was obtained. The ratio of 2-methylimidazole naphthalene trisulfonate to ammonium persulfate in the mixed solution of 2-methylimidazole naphthalene trisulfonate aqueous solution and ammonium persulfate aqueous solution is a mass ratio, and 2-methylimidazole naphthalene trisulfonate 1 On the other hand, it was 0.64 ammonium persulfate.

Example 4
The same operation as in Example 1 was performed except that a 70% naphthalene trisulfonic acid 4-methylimidazole aqueous solution (pH 5) was used instead of a 70% naphthalene trisulfonic acid butylamine aqueous solution (pH 5). As a result, a conductive composition was obtained. The ratio of 4-methylimidazole naphthalene trisulfonate to ammonium persulfate in the mixed solution of 4-methylimidazole naphthalene trisulfonate aqueous solution and ammonium persulfate aqueous solution is a mass ratio, and 4-methylimidazole naphthalene trisulfonate 1 On the other hand, it was 0.64 ammonium persulfate.

Example 5
Conducting in the same manner as in Example 1, except that a 70% naphthalene trisulfonic acid methylamine aqueous solution (pH 5) was used instead of the 70% naphthalene trisulfonic acid butylamine aqueous solution (pH 5). Sex composition was obtained. The ratio of methylamine naphthalene trisulfonate and ammonium persulfate in the mixed solution of methylamine naphthalene trisulfonate aqueous solution and ammonium persulfate aqueous solution is a mass ratio of ammonium persulfate 0 with respect to methylamine 1 naphthalene trisulfonate. .64.

Comparative Example 1
The same operation as in Example 1 was carried out except that a 70% butylamine sulfophthalate aqueous solution (pH 5) was used in place of the 70% butylamine naphthalene trisulfonate aqueous solution (pH 5). However, in Comparative Example 1, a conductive composition film could not be formed.

Comparative Example 2
The same operation as in Example 1 was performed except that a paratoluenesulfonic acid butylamine aqueous solution (pH 5) having a concentration of 45% was used in place of the 70% naphthalenetrisulfonic acid butylamine aqueous solution (pH5).

Comparative Example 3
The same operation as in Example 1 was carried out except that a 60% methoxybenzenesulfonic acid butylamine aqueous solution (pH 5) was used instead of a butylamine trisulfonic acid butylamine aqueous solution (pH 5) having a concentration of BR> X of 70%. went.

Comparative Example 4
The same operation as in Example 1 was performed except that a 60% concentration tetrabutylsulfonic acid butylamine aqueous solution (pH 5) was used instead of the 70% concentration naphthalenetrisulfonic acid butylamine aqueous solution (pH 5).

Comparative Example 5
The same operation as in Example 1 was performed except that a butyl naphthalene sulfonate butylamine aqueous solution (pH 5) having a concentration of 45% was used instead of the butyl amine naphthalene trisulfonate aqueous solution (pH 5) having a concentration of 70%.

Comparative Example 6
Instead of 7.16 ml of an oxidizing agent / dopant solution consisting of a mixture of a butylamine naphthalene trisulfonate aqueous solution and an aqueous ammonium persulfate solution, 7.16 ml of a 40% concentration para-toluenesulfonic acid ferric solution (butanol solution) was used. Except for this, the same operation as in Example 1 was performed.

  The polyethylene dioxythiophene film formed on the ceramic plate in Examples 1 to 5 and Comparative Examples 2 to 6 was allowed to stand for 5 minutes while applying a load of 1.5 tons (t), and the film pressure was evenly distributed. After that, the surface resistance of these polyethylenedioxythiophenes was measured at room temperature (about 25 ° C.) with a 4-probe conductivity meter [MCP-T600 (trade name) manufactured by Mitsubishi Chemical Corporation] according to JIS K 7194. did. The results are shown in Table 1. In addition, measurement is performed for each sample for five points, and the numerical values shown in Table 1 are obtained by calculating an average value of the five points and rounding off the decimals. Further, as described above, in the case of Comparative Example 1, since the film could not be formed, the surface resistance was not measured.

  In addition, the polyethylene dioxythiophene films of Examples 1 to 5 and Comparative Examples 2 to 6 after measuring the surface resistance were allowed to stand in a thermostatic bath at 150 ° C. together with the ceramic plate, and the plate was taken out after storage for 100 hours. The surface resistance of the polyethylenedioxythiophene film was measured in the same manner as described above, and the increase rate of the surface resistance due to storage was examined based on the measurement result. The results are also shown in Table 1. The increase rate of the surface resistance is obtained by dividing the surface resistance value after storage by the initial surface resistance value (that is, the surface resistance value before storage) and expressed as a percentage (%). The formula for calculating the increase rate of the surface resistance is as follows.

  As shown in Table 1, Examples 1 to 5 had a smaller initial surface resistance than Comparative Examples 2 to 5, and a smaller increase in surface resistance due to storage than Comparative Example 6. In Examples 1 to 5, a polyethylene dioxythiophene film having a dense surface (clean) was formed. In Comparative Examples 2 to 5, only a film having a sparse surface could be formed. This is considered to be due to the fact that the oxidizing agent and dopant used in Examples 1 to 5 have higher reaction efficiency for producing polyethylene dioxythiophene than the oxidizing agent and dopant used in Comparative Examples 2 to 5. In Comparative Example 6, a dense film was formed in the same manner as in Examples 1 to 5, but as described above, Comparative Example 6 has a high rate of increase in surface resistance due to storage. Compared with Examples 1-5, the practicality was lacking.

Next, evaluation with an aluminum winding type solid electrolytic capacitor is shown.
[Evaluation with aluminum wound solid electrolytic capacitor]
Example 6
After etching the surface of the aluminum foil, a lead terminal is attached to the anode on which the dielectric layer is formed by performing a chemical conversion treatment, and the lead terminal is attached to the cathode made of aluminum foil. Was wound through a separator to produce a capacitor element.

  Next, 3.58 ml of an aqueous solution of butylamine naphthalene trisulfonate (pH 5) having a concentration of 70%, 3.58 ml of an aqueous solution of ammonium persulfate having a concentration of 45%, 0.26 ml of an aqueous solution of dimethyllaurylamine oxide having a concentration of 35%, and 3,4 -2 ml of ethylenedioxythiophene was placed in a vial with a tight stopper and mixed for 10 minutes, and then the capacitor element was quickly immersed therein. It was pulled out after 1 minute, polymerized at room temperature for 2 hours, then washed with ethanol for 2 hours, heated at 150 ° C. for 180 minutes to complete the polymerization, and then placed in an aluminum outer case and sealed. Thereafter, aging was performed while applying a rated voltage of 25 V at 130 ° C. to produce an aluminum-wound solid electrolytic capacitor. In addition, the ratio of butylamine naphthalene trisulfonate and ammonium persulfate in the mixed solution used for the above polymerization was 0.64 ammonium persulfate with respect to butylamine 1 naphthalene trisulfonate in terms of mass ratio.

Example 7
Except for using 3.85 ml of a naphthalene trisulfonic acid butylamine aqueous solution having a concentration of 70%, 3.85 ml of an aqueous solution of 2-methylimidazole naphthalene trisulfonic acid having a concentration of 80% (pH 5) was used. Thus, an aluminum-wound solid electrolytic capacitor was produced. The ratio of 2-methylimidazole naphthalene trisulfonate to ammonium persulfate in the mixed solution used for polymerization was 0.56 ammonium persulfate with respect to 2-methylimidazole naphthalene trisulfonate 1 in terms of mass ratio. It was.

Example 8
Implemented except that 3.58 ml of 80% naphthalene trisulfonic acid 2-ethyl-4-methylimidazole aqueous solution (pH 5) was used instead of 3.58 ml of 70% naphthalene trisulfonic acid butylamine aqueous solution. The same operation as in Example 6 was performed to produce an aluminum wound solid electrolytic capacitor. In addition, the ratio of 2-ethyl-4-methylimidazole naphthalene trisulfonate and ammonium persulfate in the mixed solution used for the polymerization is a mass ratio with respect to 2-ethyl-4-methylimidazole 1 of naphthalene trisulfonate. The ammonium persulfate was 0.56.

Example 9
The same operation as in Example 6 was performed except that 3.58 ml of a 70% concentration naphthalene trisulfonic acid butylamine aqueous solution and a 70% concentration naphthalene trisulfonic acid ethylamine aqueous solution (pH 5) were used. This was done to produce an aluminum wound solid electrolytic capacitor. The ratio of ethylamine naphthalene trisulfonate and ammonium persulfate in the mixed solution used for the polymerization was 0.64 ammonium persulfate with respect to ethylamine naphthalene trisulfonate 1 in terms of mass ratio.

Example 10
Example 6 was the same as Example 6 except that 3.58 ml of an aqueous solution of 2-methylimidazole naphthalene trisulfonate having a concentration of 80% (pH 5) was used instead of 3.58 ml of an aqueous solution of butylamine naphthalene trisulfonate having a concentration of 70%. Thus, an aluminum-wound solid electrolytic capacitor was produced. The ratio of 2-methylimidazole naphthalene trisulfonate to ammonium persulfate in the mixed solution used for polymerization was 0.56 ammonium persulfate with respect to 2-methylimidazole naphthalene trisulfonate 1 in terms of mass ratio. It was.

Comparative Example 7
The same operation as in Example 6 was performed except that a 70% -concentrated butylamine sulfophthalate aqueous solution (pH 5) was used instead of the 70% -concentrated naphthalenetrisulfonic acid butylamine aqueous solution.

Comparative Example 8
The same operations as in Example 6 were performed except that a methoxybenzenesulfonic acid butylamine aqueous solution (pH 5) having a concentration of 65% was used instead of the butylamine naphthalenetrisulfonic acid aqueous solution having a concentration of 70%.

Comparative Example 9
The same operations as in Example 6 were carried out except that a 45% paratoluenesulfonic acid butylamine aqueous solution (pH 5) was used in place of the 70% naphthalenetrisulfonic acid butylamine aqueous solution.

Comparative Example 10
The same operation as in Example 6 was performed except that a butylamine naphthalene sulfonate aqueous solution (pH 5) having a concentration of 60% was used instead of the butylamine naphthalene trisulfonate aqueous solution having a concentration of 70%. The capacitor element could not be immersed because the solution solidified at the time of mixing.

Comparative Example 11
The same operation as in Example 6 was performed except that a naphthalenesulfonic acid aqueous solution having a concentration of 80% was used instead of the aqueous solution of naphthalenetrisulfonic acid butylamine having a concentration of 70%. Since the solution solidified, the capacitor element could not be immersed.

Comparative Example 12
A 40% concentration para-toluenesulfonic acid ferric solution (butanol solution) and 3,4-ethylenedioxythiophene were mixed at a mass ratio of 4: 1, shaken vigorously for 10 seconds, and then quickly immersed in the capacitor element. Except for the above, the same operation as in Example 6 was performed.

Comparative Example 13
The same operation as in Example 6 was performed until polymerization was performed at room temperature for 1 hour using a solution obtained by diluting the concentration of all reagents other than 3,4-ethylenedioxythiophene twice. After repeating this operation once more, polymerization was completed by heating and polymerizing at 40 ° C. for 20 minutes, 70 ° C. for 30 minutes, 130 ° C. for 1 hour, and 180 ° C. for 20 minutes, and then the same as in Example 6. An aluminum-wound solid electrolytic capacitor was produced by the above operation.

  About the aluminum winding type solid electrolytic capacitors of Examples 6 to 10 and Comparative Examples 7 to 9 and Comparative Examples 12 to 13 produced as described above, the capacitance, ESR (equivalent series resistance) and leakage current were measured. In addition, the occurrence of leakage current failure was examined. The results are shown in Table 2. A method for measuring capacitance, ESR and leakage current, and a method for testing whether or not a leakage current failure has occurred are as follows.

Capacitance:
The capacitance was measured at 25 ° C. and 120 Hz using an LCR meter (4284A) manufactured by HEWLETT PACKARD.

ESR:
ESR was measured at 25 ° C. and 100 kHz using an LCR meter (4284A) manufactured by HEWLETT PACKARD.

Leak current:
After applying a rated voltage of 25 V to an aluminum-wound solid electrolytic capacitor at 25 ° C. for 60 seconds, leakage current was measured with a digital oscilloscope.

Occurrence of leakage current failure:
The leakage current was measured in the same manner as in the case of the leakage current, and it was determined that a leakage current failure occurred when the leakage current was 83 μA or more.

  In addition, measurement is performed for each sample for 30 samples, and the numerical values shown in Table 2 regarding the capacitance, ESR, and leakage current are obtained by calculating the average value of the 30 values and rounding off the decimals. is there. In addition, when displaying the result of examining whether or not this leakage current failure occurs in Table 2, the total number of capacitors used in the test is shown in the denominator, and the number of capacitors where leakage current failure has occurred is shown in the numerator. Is displayed. However, the leakage current value is an average value for those in which no leakage current failure occurred.

  As shown in Table 2, the aluminum wound solid electrolytic capacitors of Examples 6 to 10 have a larger capacitance than the aluminum wound solid electrolytic capacitors of Comparative Examples 7 to 9 and Comparative Example 13, and Compared with the aluminum wound solid electrolytic capacitor of Comparative Example 12, the ESR was small, and the leakage current was small and the occurrence of leakage current failure was small.

  Further, as is apparent from the results shown in Table 2, the aluminum wound solid electrolytic capacitors of Comparative Examples 7 to 9 and Comparative Example 13 have a small capacitance and an ESR that is too large, and are used as capacitors. Did not have the necessary properties. Further, the aluminum-wound solid electrolytic capacitor of Comparative Example 12 has the same characteristics as the aluminum-wound solid electrolytic capacitors of Examples 6 to 10 as far as the capacitance and ESR are seen, but the leakage current is poor. Even when the leakage current failure did not occur much, the leakage current was large compared to the aluminum wound solid electrolytic capacitors of Examples 6 to 10, and lacked practicality.

  Next, 20 capacitors each selected at random from the aluminum wound solid electrolytic capacitors of Examples 6 to 10 and Comparative Examples 12 to 13 were stored at 105 ° C. at 1000 ° C. for 1000 hours, and then statically static as described above. The capacitance, ESR, and leakage current were measured, and the presence or absence of leakage current failure was examined. The results are shown in Table 3. The values of capacitance, ESR, and leakage current shown in Table 3 are obtained by calculating an average value of 20 pieces and rounding off the decimal part.

  As is clear from the comparison between the results shown in Table 2 and the results shown in Table 3, the aluminum-wound solid electrolytic capacitors of Examples 6 to 10 have little decrease in capacitance and increase in ESR due to storage, and Although there was little increase in leakage current and no occurrence of leakage current failure, the aluminum winding solid electrolytic capacitors of Comparative Examples 12 to 13 had increased ESR and leakage current due to storage in the aluminum windings of Examples 6 to 10. It was larger than the type solid electrolytic capacitor and the occurrence of defective leakage current was also observed.

Next, evaluation with a tantalum solid electrolytic capacitor will be described.
[Evaluation with tantalum solid electrolytic capacitors]
Example 11
In a state where the tantalum sintered body was immersed in a phosphoric acid aqueous solution having a concentration of 0.1%, chemical conversion treatment was performed by applying a voltage of 12 V to form a dielectric film on the surface of the tantalum sintered body. Next, the tantalum sintered body was immersed in an ethanol solution of 3,4-ethylenedioxythiophene having a concentration of 35%, taken out after 1 minute, and left for 5 minutes. Thereafter, a butylamine naphthalene trisulfonate aqueous solution (pH 5) having a concentration of 70%, an ammonium persulfate aqueous solution having a concentration of 40%, and a decyldimethylamine oxide aqueous solution having a concentration of 20% were prepared in a mass of 200: 200: 1. It was immersed in an oxidizing agent / dopant solution containing an emulsifier composed of a mixture mixed at a ratio, taken out after 30 seconds, and allowed to stand at room temperature for 60 minutes for polymerization. Thereafter, the tantalum sintered body was immersed in pure water and allowed to stand for 30 minutes, then taken out and dried at 70 ° C. for 30 minutes. After repeating this operation 12 times, a polyethylene dioxythiophene layer was covered with a carbon paste and a silver paste to produce a tantalum solid electrolytic capacitor. The ratio of butylamine naphthalene trisulfonate and ammonium persulfate in the oxidizing agent / dopant solution was 0.57 ammonium persulfate with respect to butylamine 1 naphthalene trisulfonate in terms of mass ratio.

Example 12
The same operation as in Example 11 was performed except that an aqueous solution of 2-methylimidazole naphthalene trisulfonate having a concentration of 80% (pH 5) was used instead of the aqueous solution of butylamine naphthalene trisulfonate having a concentration of 70% (pH 5). As a result, a tantalum solid electrolytic capacitor was obtained. The ratio of 2-methylimidazole naphthalene trisulfonate and ammonium persulfate in the oxidizing agent / dopant solution was 0.57 ammonium persulfate with respect to 2-methylimidazole naphthalene trisulfonate 1 in terms of mass ratio. .

Comparative Example 14
The same operation as in Example 11 except that the aqueous solution of butylamine sulfophthalate (pH 5) having a concentration of 70% was used instead of the aqueous solution of butylamine naphthalene trisulfonate (pH 5) having a concentration of 70% and the number of polymerizations was 18 times. Went.

Comparative Example 15
The same operation as in Example 11 was performed, except that a 70% concentration of a butylamine phenol sulfonate aqueous solution (pH 5) was used instead of the 70% concentration of a butylamine trisulfonate butylamine aqueous solution (pH 5).

Comparative Example 16
The same operation as in Example 11 was performed except that an ethanol solution of ferric paratoluenesulfonic acid having a concentration of 35% was used instead of the oxidizing agent / dopant solution in Example 11.

  For the tantalum solid electrolytic capacitors of Examples 11 to 12 and Comparative Examples 14 to 16 produced as described above, the capacitance and ESR were measured in the same manner as in Example 6. The results are shown in Table 4. In addition, the measurement is performed for each sample by 20 pieces, and the numerical values shown in Table 4 are obtained by calculating an average value of the 20 pieces and rounding off after the decimal point.

  As shown in Table 4, the tantalum solid electrolytic capacitors of Examples 11 to 12 have larger capacitance and lower ESR than the tantalum solid electrolytic capacitor of Comparative Example 14, and are excellent as tantalum solid electrolytic capacitors. Had. The tantalum solid electrolytic capacitors of Comparative Examples 15 to 16 are not inferior to the tantalum solid electrolytic capacitors of Examples 11 to 12 as long as the capacitance and ESR measurement results are seen, but as shown below. The increase in ESR when stored at a high temperature was large, and there was a problem in storage characteristics.

  Next, after storing 20 capacitors each randomly selected from the tantalum solid electrolytic capacitors of Examples 11 to 12 and Comparative Examples 14 to 16 at 105 ° C. for 400 hours, the capacitance and ESR was measured. The results are shown in Table 5. In addition, the numerical value shown in Table 5 calculates | requires 20 average values, respectively, and rounds off the decimal part.

  As is clear from the comparison between the results shown in Table 4 and the results shown in Table 5, in the tantalum solid electrolytic capacitors of Examples 11 to 12, the decrease in capacitance and the increase in ESR due to storage at high temperature are not so large. On the other hand, the tantalum solid electrolytic capacitors of Comparative Examples 14 to 16 had a large increase in ESR due to storage, and had a problem in storage characteristics.

  Next, the tantalum solid electrolytic capacitors of Examples 11 to 12 and Comparative Examples 14 to 16 are disassembled, and the conductive polymer used as the solid electrolyte (incorporates a dopant and polymerizes to have conductivity). In addition, the capacitor elements in the state where the 3,4-ethylenedioxythiophene polymer) layer was exposed were subjected to ESCA (photoelectron spectroscopy), respectively, the dopant S (sulfur) and the constituent monomer 3,4-ethylenedioxythiophene. S (sulfur) was measured. The measurement was performed five times for each capacitor, the average value was calculated, and the molar ratio of the dopant S to the monomer S was determined. The results are shown in Table 6.

  As described above, Systhetic Metals, 101 561-564 (1999), K.A. E. According to Aasmundtveut, when conducting polymer obtained by polymerizing 3,4-ethylenedioxythiophene using ferric (III) paratoluenesulfonate as an oxidant and dopant, washing and drying, the polymer is analyzed. The ratio of S (sulfur) of paratoluenesulfonic acid as a dopant to S (sulfur) of 3,4-ethylenedioxythiophene as a constituent monomer is 1 in molar ratio regardless of the charging ratio of both. : 4 reported. That is, the molar ratio of dopant: monomer is 1: 4.

  On the other hand, as shown in Table 6, the ratio of the dopant to the constituent monomer in the conductive polymer of the capacitor obtained in Examples 11 to 12 of the present invention is 1.0: 1.9. It is in the range of -1.0: 2.4, and the one using the oxidant and dopant of the present invention is more in the molar ratio of the dopant to the monomer than using ferric paratoluenesulfonate as the oxidant and dopant. Is high. In addition, the dopant in the conductive polymer of the tantalum solid electrolytic capacitors of Examples 11 to 12 described above was dedoped with an aqueous ammonia solution, and then LC-MS (liquid chromatography-mass spectrum, trade name: JMS-T100LC, JEOL Ltd. As a result, sulfuric acid and naphthalene trisulfonic acid were detected.

Claims (33)

  That at least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups is dissolved at a concentration of 40% by mass or more. A dopant solution for conducting polymer.   A benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups is dissolved at a concentration of 70% by mass or more. The dopant solution for conductive polymers according to 1.   The dopant solution for conductive polymers according to claim 1 or 2 containing an emulsifier.   The conductive polymer dopant solution according to claim 3, wherein the emulsifier is an alkylamine oxide having an alkyl group having 1 to 20 carbon atoms.   The alkyl group of the alkylamine constituting the alkylamine salt of a benzene skeleton sulfonic acid having two or more sulfone groups or a naphthalene skeleton sulfonic acid having three or more sulfone groups has 1 to 12 carbon atoms. The dopant solution for conductive polymers in any one of.   The imidazole constituting the benzene sulfonic acid having two or more sulfone groups or the imidazole salt of the naphthalene skeleton sulfonic acid having three or more sulfone groups is an alkyl group having 1 to 20 carbon atoms or phenyl at the 2- or 4-position. The dopant solution for conductive polymers in any one of Claims 1-4 substituted by group.   pH is 1 or more, The dopant solution for conductive polymers in any one of Claims 1-6.   8. The conductive polymer dopant solution according to claim 7, wherein the pH is 4 or more.   As imidazole salts of benzene skeleton sulfonic acid having two or more sulfone groups or naphthalene skeleton sulfonic acid having three or more sulfone groups, benzenedisulfonic acid 2-methylimidazole, benzenedisulfonic acid 4-methylimidazole, naphthalenetrisulfonic acid 2- The dopant solution for conductive polymers according to any one of claims 1 to 8, comprising methylimidazole, 4-methylimidazole naphthalenetrisulfonate or 2-ethyl-4-methylimidazole naphthalenetrisulfonate.   Oxidizing agent / dopant which is a mixture of at least one selected from benzene sulfonic acid having two or more sulfone groups or alkylamine salt or imidazole salt of naphthalene skeleton sulfonic acid having three or more sulfone groups and organic salt of persulfate And at least one selected from alkylamine salts or imidazole salts of benzene skeleton sulfonic acid having two or more sulfone groups or naphthalene skeleton sulfonic acid having three or more sulfone groups by mass ratio: 1 On the other hand, a persulfuric acid organic salt: 0.1 to 1.5, a conductive polymer oxidizing agent and dopant solution.   The oxidant / dopant solution for a conductive polymer according to claim 10, wherein a persulfuric acid organic salt is dissolved in the dopant solution according to claim 1.   The oxidant / dopant solution for a conductive polymer according to claim 10 or 11, wherein the concentration of the oxidant / dopant is 40% by mass or more.   As an imidazole salt of a benzene skeleton sulfonic acid having two or more sulfonic groups or a naphthalene skeleton sulfonic acid having three or more sulfonic groups, benzene disulfonic acid 2-methylimidazole, benzenedisulfonic acid 4-methylimidazole, naphthalene trisulfonic acid 2 The oxidizing agent and dopant solution for conductive polymers according to any one of claims 10 to 12, comprising methyl imidazole, 4-methylimidazole naphthalene trisulfonate or 2-ethyl-4-methylimidazole naphthalene trisulfonate.   The oxidant / dopant solution for a conductive polymer according to any one of claims 10 to 13, wherein the persulfate organic salt is ammonium persulfate.   A mixture of at least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups and a persulfate organic salt as an oxidizing agent and a dopant A conductive composition obtained by polymerizing at least one monomer selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof, and aniline or a derivative thereof. The electrically conductive composition according to claim 15, wherein the thiophene derivative is 3,4-ethylenedioxythiophene.   The alkyl group of the alkylamine constituting the alkylamine salt of a benzene skeleton sulfonic acid having two or more sulfone groups or a naphthalene skeleton sulfonic acid having three or more sulfone groups has 1 to 12 carbon atoms. The electroconductive composition as described in.   The imidazole constituting the benzene sulfonic acid having two or more sulfone groups or the imidazole salt of the naphthalene skeleton sulfonic acid having three or more sulfone groups is an alkyl group having 1 to 20 carbon atoms or phenyl at the 2- or 4-position. The electroconductive composition according to any one of claims 15 to 17, which is substituted with a group. The conductive composition according to claim 15, wherein the persulfate organic salt is ammonium persulfate.   A mixture of at least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups and a persulfate organic salt as an oxidizing agent and a dopant Solid electrolysis characterized in that a conductive composition obtained by polymerizing at least one monomer selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof and aniline or a derivative thereof is formed as a solid electrolyte Capacitor.   The solid electrolytic capacitor according to claim 20, wherein the thiophene derivative is 3,4-ethylenedioxythiophene.   The alkyl group of the alkylamine constituting the alkylamine salt of a benzene skeleton sulfonic acid having two or more sulfone groups or a naphthalene skeleton sulfonic acid having three or more sulfone groups has 1 to 12 carbon atoms. The solid electrolytic capacitor described in 1.   The imidazole constituting the benzene sulfonic acid having two or more sulfone groups or the imidazole salt of the naphthalene skeleton sulfonic acid having three or more sulfone groups is an alkyl group having 1 to 20 carbon atoms or phenyl at the 2- or 4-position. The solid electrolytic capacitor according to claim 20 or 21, which is substituted with a group.   The solid electrolytic capacitor according to any one of claims 20 to 23, wherein the persulfate organic salt is ammonium persulfate.   The solid electrolytic capacitor according to any one of claims 20 to 24, wherein a molar ratio of the dopant and the constituent monomer in the conductive composition used as the solid electrolyte is 1: 0.1 to 1: 3.   Oxidizing agent / dopant comprising a mixture of at least one selected from a benzene skeleton sulfonic acid having two or more sulfone groups or an alkylamine salt or an imidazole salt of a naphthalene skeleton sulfonic acid having three or more sulfone groups, and a persulfate organic salt In the presence of the solution, at least one monomer selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof and aniline or a derivative thereof is polymerized, and the obtained conductive composition is used as a solid electrolyte to form a solid electrolytic capacitor The manufacturing method of the solid electrolytic capacitor characterized by comprising.   27. The method for producing a solid electrolytic capacitor according to claim 26, wherein the concentration of the oxidizing agent / dopant solution is 25% by mass or more.   27. The method for producing a solid electrolytic capacitor according to claim 26, wherein the solid electrolytic capacitor is an aluminum solid electrolytic capacitor, wherein the concentration of the oxidizing agent / dopant solution is 30% by mass or more and the pH is 1 or more.   29. The method for producing a solid electrolytic capacitor according to claim 28, wherein the pH of the solution of the oxidizing agent / dopant is 4 or more.   30. The method for producing a solid electrolytic capacitor according to claim 28 or 29, wherein the solid electrolytic capacitor is an aluminum-wound solid electrolytic capacitor, and the concentration of the oxidizing agent / dopant solution is 55% by mass or more.   The manufacturing method of the solid electrolytic capacitor in any one of Claims 26-30 which has added the emulsifier to the solution of an oxidizing agent and a dopant.   32. The method for producing a solid electrolytic capacitor according to claim 31, wherein the emulsifier is an alkylamine oxide having an alkyl group having 1 to 20 carbon atoms.   The capacitor element is alternately immersed in a solution of at least one monomer selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof, and aniline or a derivative thereof, and an oxidizing agent / dopant solution. 33. A method for producing a solid electrolytic capacitor according to any one of 32.