JP2012001677A - Oxidizing agent and dopant solution for producing electroconductive polymer, electroconductive polymer, solid electrolytic condenser prepared by using the same as solid electrolyte, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxidizing agent and dopant solution suitable for producing an electroconductive polymer that can provide a solid electrolytic condenser which has a low ESR and a high electrostatic capacity when used as a solid electrolyte; and to provide the electroconductive polymer having the characteristics described above and the solid electrolytic condenser using the solution.SOLUTION: To the oxidizing agent and dopant solution for producing an electroconductive polymer containing organic ferric sulphonate as the oxidizing agent and dopant and an organic solvent having a hydroxyl group, 4-20% by mass of dialkyl ether or a derivative thereof based on the organic ferric sulphonate is added. Then, oxidation polymerization of thiophen or a derivative thereof is performed using the oxidizing agent and dopant solution to produce the electroconductive polymer, and the solid electrolytic condenser is composed using the electroconductive polymer as the solid electrolyte.

Description

  The present invention relates to an oxidizing agent / dopant solution for producing a conductive polymer, a conductive polymer produced by oxidative polymerization of thiophene or a derivative thereof using the same, and a solid electrolytic capacitor using the conductive polymer as a solid electrolyte And a manufacturing method thereof.

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

  As the conductive polymer in this application, what is obtained by oxidative polymerization (chemical oxidative polymerization) of thiophene or a derivative thereof has a good balance between conductivity and heat resistance, and is highly useful. Widely used (Patent Documents 1 and 2).

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

  In manufacturing a solid electrolytic capacitor using the conductive polymer as a solid electrolyte, for example, the capacitor element is immersed in a monomer solution and pulled up, and then the capacitor element is immersed in an oxidant / dopant solution and pulled up. Polymerize or immerse the capacitor element in the oxidant / dopant solution and pull it up, then immerse the capacitor element in the monomer solution and pull it up for polymerization, or mix the oxidant / dopant solution and the monomer solution The capacitor element is immersed in a solution prepared in this manner, and then pulled up and polymerized.

  At that time, the higher the concentration of the oxidizer / dopant solution for producing the conductive polymer, the lower (smaller) the ESR (equivalent series resistance) of the obtained solid electrolytic capacitor, and the higher (larger) capacitance. Although the capacitor characteristics tend to be improved, if the concentration of the oxidizing agent / dopant solution exceeds a certain concentration, the capacitor characteristics are deteriorated.

  This is because, as the concentration of the oxidant / dopant solution for producing a conductive polymer increases, the viscosity increases and the reaction rate increases, so that the oxidant / dopant solution is spread over the details of the capacitor element. It is thought that the polymerization progresses soon and the capacitor characteristics deteriorate. This tendency varies depending on the type of the solid electrolytic capacitor, but in the case of a wound aluminum solid electrolytic capacitor, it appears when the concentration of the oxidizing agent / dopant solution for producing the conductive polymer is 55% by mass or more.

Therefore, a first solute composed of a ferric salt of aromatic sulfonic acid and a second solute selected from the group consisting of an amine salt, quaternary ammonium salt and aluminum salt of aromatic sulfonic acid are dissolved in an alcohol solvent. Thus, it has been proposed to prepare an oxidizing agent / dopant solution for producing a conductive polymer and reduce the viscosity of the oxidizing agent / dopant solution for producing a conductive polymer (Patent Document 3).
However, when it was applied in the production of solid electrolytic capacitors, sufficient results were not obtained.

JP 2003-160647 A JP 2004-265927 A JP 2010-53302 A

  In view of the circumstances as described above, the present invention has a high conductivity suitable for producing a conductive polymer capable of providing a solid electrolytic capacitor having a low ESR and a large capacitance when used as a solid electrolyte. An object of the present invention is to provide an oxidizing agent / dopant solution for molecular production, and to provide a conductive polymer and a solid electrolytic capacitor having the above characteristics using the same.

  The present invention achieves the above-mentioned object by adding a dialkyl ether or a derivative thereof in a specific ratio to an oxidizing agent / dopant solution for producing a conductive polymer, and is completed based on the object.

  That is, the present invention is an oxidant and dopant solution for producing a conductive polymer containing ferric organic sulfonate as an oxidant and dopant for producing a conductive polymer and an organic solvent having a hydroxyl group, The present invention relates to an oxidizing agent / dopant solution for producing a conductive polymer, wherein a dialkyl ether or a derivative thereof is added in an amount of 4 to 20% on a mass basis with respect to the ferric organic sulfonate.

The present invention also relates to a conductive polymer produced by oxidative polymerization of thiophene or a derivative thereof using the above oxidizing polymer / dopant solution for producing a conductive polymer.
Furthermore, the present invention provides a solid electrolytic capacitor characterized in that a conductive polymer produced by oxidative polymerization of thiophene or a derivative thereof using the oxidant / dopant solution for producing a conductive polymer is used as a solid electrolyte. And a manufacturing method thereof.

  The oxidant / dopant solution for producing a conductive polymer of the present invention (hereinafter simply referred to as “oxidant / dopant solution”) reduces the viscosity of the oxidant / dopant solution by adding a dialkyl ether or a derivative thereof. Therefore, it is possible to suppress the increase in viscosity accompanying the increase in the concentration of the oxidizing agent / dopant (hereinafter simply referred to as “oxidant / dopant”) for the production of the conductive polymer, and increase the viscosity. The conductive polymer produced by oxidative polymerization of thiophene or its derivatives using an oxidant / dopant solution with a high concentration while suppressing the ESR has an ESR when used as a solid electrolyte of a solid electrolytic capacitor. A solid electrolytic capacitor having a low capacitance and a large capacitance can be provided.

  In the present invention, as the organic sulfonic acid of ferric organic sulfonate serving as an oxidizing agent and a dopant, for example, aromatic series such as benzene sulfonic acid or its derivative, naphthalene sulfonic acid or its derivative, anthraquinone sulfonic acid or its derivative High-molecular sulfonic acids such as sulfonic acid, polystyrene sulfonic acid, sulfonated polyester, and phenol sulfonic acid novolak resin are preferably used.

  Examples of the benzenesulfonic acid derivative in the benzenesulfonic acid or derivative thereof include toluenesulfonic acid, ethylbenzenesulfonic acid, propylbenzenesulfonic acid, butylbenzenesulfonic acid, dodecylbenzenesulfonic acid, methoxybenzenesulfonic acid, ethoxybenzenesulfonic acid, Examples thereof include propoxybenzene sulfonic acid, butoxybenzene sulfonic acid, phenol sulfonic acid, cresol sulfonic acid, and benzene disulfonic acid. Examples of naphthalene sulfonic acid derivatives in naphthalene sulfonic acid or its derivatives include naphthalene disulfonic acid and naphthalene trisulfonic acid. Methyl naphthalene sulfonic acid, ethyl naphthalene sulfonic acid, propyl naphthalene sulfonic acid, butyl naphthalene sulfonic acid, etc. Gerare, as the anthraquinone sulfonic acid derivatives in anthraquinone sulfonic acid or its derivatives, e.g., anthraquinone disulfonic acid, anthraquinone-trisulfonic acid. Among these aromatic sulfonic acids, toluene sulfonic acid, methoxybenzene sulfonic acid, phenol sulfonic acid, naphthalene sulfonic acid, naphthalene trisulfonic acid and the like are preferable, and paratoluene sulfonic acid and methoxybenzene sulfonic acid are particularly preferable. Paratoluenesulfonic acid is preferred.

  The ferric organic sulfonate is preferably one having a lower organic sulfonic acid ratio than the molar ratio of the organic sulfonic acid to the iron of 1: 3. This is because the reaction rate of the ferric organic sulfonate can be slightly reduced by making the organic sulfonic acid to iron molar ratio less than the stoichiometric molar ratio of 1: 3. The molar ratio of organic sulfonic acid to iron is preferably up to about 1: 2, more preferably about 1: 2.2, more preferably about 1: 2.4, and about 1: 2.75. Even more preferred is.

  The organic solvent having a hydroxyl group is for dissolving the ferric organic sulfonate as the oxidant / dopant into a solution. Examples of the organic solvent having a hydroxyl group include methanol (methyl alcohol). ), Ethanol (ethyl alcohol), propanol (propyl alcohol), butanol (butyl alcohol), ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, etc., among them, methanol, ethanol, propanol Alcohol having 1 to 4 carbon atoms such as butanol is preferable.

Examples of dialkyl ethers or derivatives thereof include dialkyl ethers represented by the following general formula (1), alkylene glycol dialkyl ethers represented by general formula (2), and dialkyl ethers represented by general formula (3). Suitable examples include alkylene glycol dialkyl ethers.
General formula (1):
R ¹ —O—R ²
(In the formula, R ¹ and R ² are each an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and these R ¹ and R ² may be the same or different from each other, provided that R ¹ is different. And R ² are simultaneously CH ₃ )
General formula (2):
R ³ —O—R ⁵ —O—R ⁴
(In the formula, R ³ and R ⁴ are aliphatic hydrocarbon groups having 1 to ⁴ carbon atoms, and these R ³ and R ⁴ may be the same or different from each other. R ⁵ is carbon. (It is an alkylene group having a number of 1 to 3.)
General formula (3):
R ⁶ —O— (R ⁸ —O) ₂ —R ⁷
(In the formula, R ⁶ and R ⁷ are aliphatic hydrocarbon groups having 1 to 4 carbon atoms, and these R ⁶ and R ⁷ may be the same or different from each other. R ⁸ is carbon. (It is an alkylene group having a number of 1 to 3.)

Examples of the dialkyl ether represented by the general formula (1) include diethyl ether, dipropyl ether, methyl propyl ether, ethyl propyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, and butyl propyl ether. . In particular, dipropyl ether, dibutyl ether, butyl methyl ether, and the like are preferable. Regarding the propyl group, either normal or iso may be used, and regarding the butyl group, normal, iso, sec, or tert may be used. The same applies to dialkyl ethers or derivatives thereof shown below. In the present invention, dimethyl ether has a boiling point of −24.8 ° C. (usually, dimethyl ether in which R ¹ and R ² are both alkyl groups having 1 carbon atom, that is, methyl group, is excluded from dialkyl ether. This is because the pressure is too low and is a gas at room temperature, and cannot be used to lower the viscosity of the oxidizer / dopant solution.

Examples of the alkylene glycol dialkyl ether represented by the general formula (2) include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, methylene glycol dimethyl ether, methylene glycol diethyl ether, and methylene glycol. Examples include dipropyl ether, methylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol dimethyl ether, propylene glycol dipropyl ether, propylene glycol dibutyl ether, and those whose alkyl groups are different between R ³ and R ^4. Dimethyl ether, ethylene glycol diethyl ether, Such as Chi glycol dimethyl ether are preferred.

Examples of the dialkylene glycol dialkyl ether represented by the general formula (3) include diethylene glycol dimethyl ether [CH ₃ —O—CH ₂ CH ₂ —O—CH ₂ CH ₂ —O—CH ₃ ], diethylene glycol diethyl ether [ CH ₃ CH ₂ —O—CH ₂ CH ₂ —O—CH ₂ CH ₂ —O—CH ₂ CH ₃ ] and the like.

  The dialkyl ethers or derivatives thereof exemplified above can be used alone or in combination of two or more. The dialkyl ether or derivative thereof has a viscosity of the oxidizing agent / dopant solution. It has a lowering effect and can suppress the increase in viscosity accompanying the increase in the concentration of ferric organic sulfonate. Therefore, the adverse effect associated with the increase in viscosity (increasing ESR or The concentration of the oxidizing agent / dopant solution can be increased without incurring a decrease in the capacity, thereby reducing the ESR of the solid electrolytic capacitor and increasing the capacitance, thereby improving the capacitor characteristics.

  Some of these dialkyl ethers or derivatives thereof have a high boiling point (for example, diethylene glycol diethyl ether has a boiling point of 187 ° C.), and they may remain in the conductive polymer without being removed by ordinary drying. However, even if it remains, it does not cause an increase in ESR or a decrease in capacitance as shown in the examples described later.

  And the addition amount with respect to ferric organic sulfonate of this dialkyl ether or its derivative is 4 to 20% (namely, dialkyl ether or its derivative is 4 to 4 with respect to 100 mass parts of ferric organic sulfonate. 20 parts by mass), when the addition amount of the dialkyl ether or derivative thereof is less than the above, the effect of lowering the viscosity is not sufficiently exhibited, and when the addition amount of the dialkyl ether or derivative thereof is more than the above In addition, there is little increase in the effect accompanying the increase in the amount added, resulting in an increase in cost, and there is a possibility that the mixture becomes immiscible and the storage stability of the oxidizing agent / dopant solution is lowered. And the addition amount with respect to ferric organic sulfonate of this dialkyl ether or its derivative is 5% or more on a mass basis within the said range, and 16% or less is preferable.

  In the case of a butanol-based solution using butanol as a solvent, an oxidizing agent / dopant solution for producing a conductive polymer has so far been made to increase the concentration of ferric organic sulfonate to 54% by mass. However, the addition of the dialkyl ether or derivative thereof as described above, while suppressing the occurrence of harmful effects associated with the increase in concentration, the organic sulfonic acid secondary The concentration of iron can be increased to about 60% by mass, and in an ethanol-based solution using ethanol as a solvent, the concentration of ferric organic sulfonate can be 60% by mass until now. Although it was the limit that could increase the concentration without causing the harmful effects of increasing the concentration of ferric organic sulfonate, the concentration could be increased by adding the above dialkyl ether or its derivatives. While Nau suppressing the occurrence of adverse effects, the concentration of ferric organic sulfonic acid can be high concentration up to about 65 wt%, whereby it is possible to obtain a good solid electrolytic capacitor characteristics.

  In addition, in a methanol-based oxidant / dopant solution using methanol as a solvent and a propanol-based oxidant / dopant solution using propanol as a solvent, addition of a dialkyl ether or a derivative thereof, respectively, The high concentration can be achieved without causing the harmful effects associated with the high concentration of iron, thereby improving the characteristics of the solid electrolytic capacitor.

  In the present invention, thiophene or a derivative thereof is used as a monomer for producing a conductive polymer. This is because, as described above, the conductive polymer obtained by polymerizing thiophene or its derivative has a good balance between conductivity and heat resistance, and has a capacitor characteristic superior to that of other monomers. This is based on the reason that a capacitor is easily obtained.

  Examples of the thiophene derivative in the thiophene or the derivative thereof include 3,4-ethylenedioxythiophene, 3-alkylthiophene, 3-alkoxythiophene, 3-alkyl-4-alkoxythiophene, and 3,4-alkylthiophene. 3,4-alkoxythiophene, alkylated ethylenedioxythiophene obtained by modifying the above 3,4-ethylenedioxythiophene with an alkyl group, and the number of carbon atoms of the alkyl group or alkoxy group is 1-16. Are preferable, and 1-4 are especially preferable.

  The alkylated ethylenedioxythiophene obtained by modifying the 3,4-ethylenedioxythiophene with an alkyl group will be described in detail. The 3,4-ethylenedioxythiophene and the alkylated 3,4-ethylenedioxythiophene are as follows. It corresponds to the compound represented by the general formula (4).

（式中、Ｒ^９は水素またはアルキル基である）

(Wherein R ⁹ is hydrogen or an alkyl group)

Then, the compound in which R ⁹ in the general formula (4) is hydrogen is 3,4-ethylenedioxythiophene, which is represented by the IUPAC name, “2,3-dihydro-thieno [3,4- b] [1,4] dioxin (2,3-Dihydro-thieno [3,4-b] [1,4] dioxine) ", but this compound has a generic name rather than the IUPAC name. In this document, this “2,3-dihydro-thieno [3,4-b] [1,4] dioxin” is referred to as “3,4-ethylenedioxythiophene”. 4-Ethylenedioxythiophene ”. When R ⁹ in the general formula (4) is an alkyl group, the alkyl group is preferably one having 1 to 4 carbon atoms, that is, a methyl group, an ethyl group, a propyl group, or a butyl group, Specifically, a compound in which R ⁹ in the general formula (4) is a methyl group is represented by IUPAC name, “2-methyl-2,3-dihydro-thieno [3,4-b] [1 , 4] dioxin (2-Methyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxine) ”, which is hereinafter simplified to“ methylated ethylenedioxythiophene ”. Is displayed. A compound in which R ⁹ in the general formula (4) is an ethyl group is represented by IUPAC name, “2-ethyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin (2- Ethyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxine) ”, which will be simplified and represented as“ ethylated ethylenedioxythiophene ”. A compound in which R ⁹ in the general formula (4) is a propyl group is represented by “IUPAC name”, “2-propyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin (2- Propyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxine) ”, which will be simplified and represented as“ propylated ethylenedioxythiophene ”. A compound in which R ⁹ in the general formula (4) is a butyl group is represented by “IUPAC name”, “2-butyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin ( 2-Butyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxine) ”, which will be simplified and represented as“ butylated ethylenedioxythiophene ”. Further, “2-alkyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin” is hereinafter simply expressed as “alkylated ethylenedioxythiophene”. Among these alkylated ethylenedioxythiophenes, methylated ethylenedioxythiophene, ethylated ethylenedioxythiophene, propylated ethylenedioxythiophene, and butylated ethylenedioxythiophene are preferable, and in particular ethylated ethylenedioxythiophene. Propylated ethylenedioxythiophene is preferred.

  And 3,4-ethylenedioxythiophene (ie 2,3-dihydro-thieno [3,4-b] [1,4] dioxin) and alkylated ethylenedioxythiophene (ie 2-alkyl-2, 3-dihydro-thieno [3,4-b] [1,4] dioxin) is preferably used as a mixture, and the mixing ratio is 0.1: 1 to 1: 0.1 in terms of molar ratio. In particular, 0.2: 1 to 1: 0.2, particularly 0.3: 1 to 1: 0.3 is preferable.

  The production of the conductive polymer using the oxidant / dopant solution of the present invention is usually performed when the conductive polymer is produced, and when the solid electrolytic capacitor is produced, the conductive polymer is produced. The present invention can be applied to both production of a conductive polymer by polymerization.

  Since thiophene and its derivatives that are monomers are liquid at room temperature, they can be used as they are for polymerization, and in order to make the polymerization reaction proceed more smoothly, for example, methanol, ethanol, propanol, butanol, It may be diluted with an organic solvent such as acetone or acetonitrile and used as an organic solvent solution. However, if the monomer is diluted with the organic solvent as described above, the characteristic of increasing the concentration of the oxidizing agent / dopant solution is lost, so the monomer thiophene or its derivative is mixed with the oxidizing agent / dopant solution. When used as it is, it is preferable to use thiophene or a derivative thereof as it is without diluting with a solvent.

  When a conductive polymer is normally manufactured (this normal conductive polymer is manufactured means that the conductive polymer is not manufactured by “in-situ polymerization” at the time of production of the solid electrolytic capacitor. A mixture of the oxidant / dopant solution of the present invention and the monomer thiophene or a derivative thereof (the mixing ratio is on a mass basis, and the oxidant / dopant: monomer is preferably 5: 1 to 15: 1) For example, it is carried out by oxidative polymerization at 5 to 95 ° C. for 1 to 72 hours.

  The oxidizing agent / dopant solution of the present invention has been developed so as to be suitable for producing a conductive polymer by so-called “in situ polymerization”, particularly when a solid electrolytic capacitor is produced. This will be described in detail below.

  In addition, solid electrolytic capacitors include aluminum solid electrolytic capacitors, tantalum solid electrolytic capacitors, niobium solid electrolytic capacitors, etc. Among these aluminum solid electrolytic capacitors, wound aluminum solid electrolytic capacitors and stacked aluminum solid electrolytic capacitors are also included. However, the oxidizer / dopant solution of the present invention has been developed to be particularly suitable for producing a wound aluminum solid electrolytic capacitor, and this will be described in detail.

  First, as a capacitor element of a wound aluminum solid electrolytic capacitor, after the surface of the aluminum foil is etched, a lead terminal is attached to the anode formed with a chemical conversion treatment to form a derivative layer, and the lead is connected to the cathode made of aluminum foil. A terminal prepared by attaching a terminal and winding the lead terminal-attached anode and cathode through a separator is used.

And manufacture of the winding type aluminum solid electrolytic capacitor using the said capacitor | condenser element is performed as follows, for example.
That is, the capacitor element is immersed in a mixture of the oxidant / dopant solution of the present invention and a monomer (thiophene or a derivative thereof), pulled up, and then polymerized at room temperature or under heating to polymerize the thiophene or a derivative thereof. After forming a solid electrolyte layer made of a conductive polymer having a polymer skeleton, it is immersed in water, pulled up, dried, and a capacitor element having the solid electrolyte layer is packaged with an exterior material, and wound type An aluminum solid electrolytic capacitor is produced.

  Further, as described above, instead of immersing the capacitor element in the mixture of the oxidizing agent / dopant solution of the present invention and the monomer, the monomer (thiophene or a derivative thereof) is diluted with an organic solvent such as methanol as described above. Then, after immersing the capacitor element in the monomer solution and pulling it up and drying, the capacitor element is immersed in the oxidant / dopant solution of the present invention and pulled up, and then the monomer is polymerized at room temperature or under heating, or The capacitor element is first immersed in the oxidant / dopant solution of the present invention and pulled up, and then the capacitor element is immersed in the monomer and pulled up, and then the monomer is polymerized at room temperature or under heating. Thus, a wound aluminum solid electrolytic capacitor is produced.

  In the production of solid electrolytic capacitors other than the above wound aluminum solid electrolytic capacitors, for example, laminated aluminum solid electrolytic capacitors, tantalum solid electrolytic capacitors, niobium solid electrolytic capacitors, etc., valve metals such as aluminum, tantalum, and niobium as capacitor elements In the same manner as in the case of the wound aluminum solid electrolytic capacitor, the capacitor element is used as the oxidizer of the present invention. Immerse in a mixture of a dopant solution and a monomer and pull it up to polymerize the monomer (thiophene or its derivative) at room temperature or under heating, or immerse the capacitor element in the monomer solution and pull it up and dry it, then the capacitor The element is an oxidant / dopa of the present invention Dipping in the solution and pulling up to polymerize the monomer at room temperature or under heating, or immersing the capacitor element in the oxidizing agent / dopant solution of the present invention and pulling it up, and then immersing the capacitor element in the monomer. After pulling up, the monomer is polymerized at room temperature or under heating, and these steps are repeated to form a solid electrolyte layer made of a conductive polymer, and then a carbon paste and a silver paste are attached, dried, and then packaged. Thus, a laminated aluminum solid electrolytic capacitor, a tantalum solid electrolytic capacitor, a niobium solid electrolytic capacitor, and the like are produced.

  In the production of a conductive polymer by “in situ polymerization” at the time of production of the above-described conductive polymer or solid electrolytic capacitor, the oxidizing agent / dopant solution and monomer (thiophene or derivative thereof) or monomer of the present invention The use ratio with the solution is preferably 2: 1 to 8: 1 in terms of mass ratio of ferric organic sulfonate serving as an oxidant and dopant and the monomer, and “in situ polymerization” is, for example, 10 to 300 ° C., It takes 1 to 180 minutes.

  Further, in the production of the solid electrolytic capacitor, when the capacitor element is immersed in the mixture of the oxidant / dopant solution of the present invention and the monomer, the oxidant / dopant solution of the present invention is usually prepared in advance. Mixing with monomer, but without preparing in advance, mixing organic solvent solution of ferric organic sulfonate (organic solvent solution having hydroxyl group), compound having sulfoxide group and monomer In such a mixed state, an organic solvent solution of ferric organic sulfonate corresponding to the oxidizing agent / dopant solution of the present invention and a compound having a sulfoxide group may be present.

  In addition, as disclosed in Japanese Patent Application No. 2010-08722 filed by the present applicant, in the production of a conductive polymer, a monomer having a sulfoxide group such as dimethyl sulfoxide is added to a monomer comprising thiophene or a derivative thereof as a monomer thiophene. Alternatively, if 1.5 to 20% of the derivative is added on a mass basis, the reaction rate of the oxidant in the oxidant / dopant solution can be reduced, and the adverse effect of increasing the concentration of the oxidant / dopant solution. Can be reduced.

  Therefore, when the present invention and the addition of a compound having a sulfoxide group to the above monomer are used in combination, the reduction of the viscosity according to the present invention and the action of reducing the reaction rate of the oxidizing agent based on the addition of the compound having the sulfoxide group to the monomer. Can work synergistically to obtain a solid electrolytic capacitor with better characteristics.

  Further, as disclosed in Japanese Patent Application No. 2010-08721 filed by the present applicant, in the production of a conductive polymer, a compound having a sulfoxide group such as dimethyl sulfoxide is added to an oxidizing agent / dopant solution as an organic sulfone as an oxidizing agent. If 1 to 7.5% is added to ferric oxide on a mass basis, the reaction rate of the oxidant in the oxidant / dopant solution can be reduced, and the adverse effect of increasing the concentration of the oxidant / dopant Can be reduced.

  Therefore, when the present invention and the addition of a compound having a sulfoxide group to the above oxidizing agent / dopant are used in combination, the reduction in viscosity according to the present invention and the oxidizing agent based on the addition of the compound having a sulfoxide group to the oxidizing agent / dopant Thus, a solid electrolytic capacitor with better characteristics can be obtained.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this invention is not limited only to what is illustrated by those Examples. In the following examples and the like,% in the case of indicating the concentration, the added amount, etc. is% based on mass unless otherwise specified.

[Preparation of oxidizing agent / dopant solution]
In Examples 1 to 18 and Comparative Examples 1 to 8 shown below, preparation of an oxidizing agent / dopant solution is shown. In addition, evaluation of these oxidizing agent and dopant solutions is performed by evaluation of a solid electrolytic capacitor in [Evaluation with a solid electrolytic capacitor (1)] and [Evaluation with a solid electrolytic capacitor (2)] described later.

  First, the oxidizing agent / dopant solution is an ethanol solution, and the concentration of ferric organic sulfonate as the oxidizing agent / dopant is increased to 62%. The preparation of the dopant solution will be described.

Example 1
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 7.3 g of ethylene glycol dimethyl ether [an alkylene glycol dialkyl ether in which R ³ and R ⁴ are methyl groups and R ⁵ is an ethylene group in general formula (2)] is added, and ethanol is added to 11 g. 0.0 g was added and heated at 60 ° C. for 1 hour, followed by filtration with glass filter GF75 manufactured by Advantech Toyo Co., Ltd. (GF75 is a product number; hereinafter, the company name is omitted), and the filtrate was subjected to the oxidizing agent of Example 1. Also used as a dopant solution. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 1 was 62.0%, and the amount of ethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 10.0%. The viscosity of the oxidizing agent / dopant solution of Example 1 measured with a B-type viscometer at a temperature of 25 ° C. and a rotation speed of 60 rpm was 118 mPa · s.

Example 2
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 3.7 g of ethylene glycol dimethyl ether and 14.7 g of ethanol were added, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, and the filtrate was combined with the oxidizing agent of Example 2. A dopant solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 2 was 62.0%, and the amount of ethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 5.0%. Moreover, the viscosity measured on the same conditions as Example 1 of this oxidizing agent and dopant solution of Example 2 was 120 mPa * s.

Example 3
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (a molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 5.9 g of ethylene glycol dimethyl ether and 12.5 g of ethanol were added, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, and the filtrate was combined with the oxidizing agent of Example 3. A dopant solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 3 was 62.0%, and the amount of ethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 8.0%. The viscosity of the oxidizing agent / dopant solution of Example 3 measured under the same conditions as in Example 1 was 116 mPa · s.

Example 4
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 9.5 g of ethylene glycol dimethyl ether and 8.9 g of ethanol were added and heated at 60 ° C. for 1 hour, followed by filtration with a glass filter GF75 manufactured by Advantech Toyo Co., Ltd. An oxidizing agent / dopant solution was prepared. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 4 was 62.0%, and the amount of ethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 13.0%. In addition, the viscosity of the oxidizing agent / dopant solution of Example 4 measured under the same conditions as in Example 1 was 108 mPa · s.

Example 5
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 11.7 g of ethylene glycol dimethyl ether and 6.7 g of ethanol were added, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, and the filtrate was used as the oxidizing agent of Example 5. A dopant solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 5 was 62.0%, and the amount of ethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 16.0%. Moreover, the viscosity measured under the same conditions as Example 1 of the oxidizing agent / dopant solution of Example 5 was 105 mPa · s.

Example 6
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (a molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 14.7 g of ethylene glycol dimethyl ether and 3.7 g of ethanol were added, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, and the filtrate was combined with the oxidizing agent of Example 6. A dopant solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 6 was 62.0%, and the amount of ethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 20.0%. Further, the viscosity of the oxidizing agent / dopant solution of Example 6 measured under the same conditions as in Example 1 was 100 mPa · s.

Example 7
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (a molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 3.0 g of ethylene glycol dimethyl ether and 15.4 g of ethanol were added, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, and the filtrate was combined with the oxidizing agent of Example 3. A dopant solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 3 was 62.0%, and the amount of ethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 4.0%. Moreover, the viscosity measured on the same conditions as Example 1 of this oxidizing agent and dopant solution of Example 3 was 133 mPa * s.

Example 8
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 7.3 g of dipropyl ether [dialkyl ether in which R ¹ and R ² are propyl groups in the general formula (1)] are added, and 11.1 g of ethanol is added. After heating for a period of time, the solution was filtered through a glass filter GF75, and the filtrate was used as the oxidizing agent / dopant solution of Example 8. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 8 was 62.0%, and the amount of diethyl ether added to ferric paratoluenesulfonate was 10.0%. Moreover, the viscosity measured under the same conditions as in Example 1 of the oxidizing agent / dopant solution of Example 8 was 112 mPa · s.

Example 9
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. 100 g of the above solution, methylene glycol dimethyl ether (CH ₃ —O—CH ₂ —O—CH ₂ —O—CH ₃ ) [In the general formula (2), R ³ and R ⁴ are methyl groups, and R ⁵ is methylene. 7.3 g of the basic dialkylene glycol dialkyl ether] and 11.1 g of ethanol were added, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, and the filtrate was combined with the oxidizing agent of Example 9. A dopant solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 9 was 62.0%, and the amount of methylene glycol dimethyl ether added to ferric paratoluenesulfonate was 10.0%. Further, the viscosity of the oxidizing agent / dopant solution of Example 9 measured under the same conditions as Example 1 was 106 mPa · s.

Example 10
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 7.3 g of ethylene glycol dimethyl ether, 1.8 g of dimethyl sulfoxide and 9.2 g of ethanol are added, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, The filtrate was the oxidizing agent / dopant solution of Example 10. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 10 is 62.0%, the addition amount of ethylene glycol dimethyl ether to ferric paratoluenesulfonate is 10.0%, The amount of dimethyl sulfoxide added to diiron was 2.5%. Further, the viscosity of the oxidizing agent / dopant solution of Example 10 measured under the same conditions as in Example 1 was 126 mPa · s.

Comparative Example 1
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. 18.4 g of ethanol was added to 100 g of the above solution, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, and the filtrate was used as an oxidizing agent / dopant solution of Comparative Example 1. The calculated solid content concentration of the oxidizing agent / dopant solution of Comparative Example 1 was 62.0%. Moreover, the viscosity measured on the same conditions as Example 1 of the oxidizing agent and dopant solution of this comparative example 1 was 148 mPa * s.

Comparative Example 2
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. To 100 g of the above solution, 2.2 g of ethylene glycol dimethyl ether and 16.2 g of ethanol are added, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, and the filtrate is used as the oxidizing agent of Comparative Example 2. A dopant solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Comparative Example 2 was 62.0%, and the amount of ethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 3.0%. Moreover, the viscosity measured on the same conditions as Example 1 of this oxidizing agent and dopant solution of the comparative example 2 was 143 mPa * s.

Comparative Example 3
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. When 18.4 g of ethylene glycol dimethyl ether was added to 100 g of the above solution, even when separated into two layers and heated at 60 ° C. for 1 hour, a uniform oxidizing agent / dopant solution was not obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Comparative Example 3 was 62.0%, and the amount of ethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 25%.

Comparative Example 4
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 73.4%. 7.3 g of ethylene glycol monomethyl ether and 11.0 g of ethanol are added to 100 g of the above solution, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75 manufactured by Advantech Toyo Co., and the filtrate is a comparative example. 4 was used as an oxidizing agent / dopant solution. The calculated solid content concentration of the oxidizing agent / dopant solution of Comparative Example 4 was 62.0%, and the amount of ethylene glycol monomethyl ether added to ferric paratoluenesulfonate was 10.0%. Moreover, the viscosity measured on the same conditions as Example 1 of the oxidizing agent and dopant solution of this comparative example 4 was 152 mPa * s.

Addition amount of the oxidizing agent of the oxidizing agent / dopant solution of Examples 1 to 10 and Comparative Examples 1 to 4 or its derivative to the ferric organic sulfonate (paratoluenesulfonic acid), the dialkyl ether or its derivative Table 1 shows the types and viscosities.
However, dialkyl ethers or derivatives thereof are simplified as follows because of space limitations.

EGDM: ethylene glycol dimethyl ether DPrE: dipropyl ether MGDM: methylene glycol dimethyl ether EGMM: ethylene glycol monomethyl ether

  In Table 1 above, the viscosity of Comparative Example 3 is not shown because, as described above, the amount of ethylene glycol dimethyl ether added is too large, and a uniform oxidizer / dopant solution cannot be obtained. Although it is because it was not, as shown in Table 1, compared with the oxidizing agent and dopant solution of Comparative Examples 1-2 and 4, the viscosity of the oxidizing agent and dopant of Examples 1 to 10 was lower.

  Next, the oxidizing agent / dopant solution was changed to a butanol-based solution, and the concentration of ferric organic sulfonate as the oxidizing agent / dopant was increased to 56%. The preparation of the dopant solution will be described.

Example 11
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (Mole ratio of iron to para-toluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 6.6 g of ethylene glycol diethyl ether [alkylene glycol dialkyl ether in which R ³ and R ⁴ are ethyl groups and R ⁵ is an ethylene group in the general formula (2)] is added, and butanol is added. 10.4 g was added and heated at 60 ° C. for 2 hours, and then filtered through a glass filter GF75, and the filtrate was used as the oxidizing agent / dopant solution of Example 11. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 11 was 56.0%, and the amount of ethylene glycol diethyl ether added to ferric paratoluenesulfonate was 10.0%. In addition, the viscosity of the oxidizing agent / dopant solution of Example 11 measured under the same conditions as in Example 1 was 127 mPa · s.

Example 12
A butanol solution (molar ratio of iron to paratoluenesulfonic acid: 1.2.77) was concentrated by distillation with ferric paratoluenesulfonate having a concentration of 40% manufactured by Teika. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 3.3 g of ethylene glycol diethyl ether and 13.7 g of butanol are added, heated at 60 ° C. for 1 hour, filtered through a glass filter GF75, and the filtrate is subjected to the oxidizing agent of Example 12. Also used as a dopant solution. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 12 was 56.0%, and the amount of ethylene glycol diethyl ether added to ferric paratoluenesulfonate was 5.0%. Further, the viscosity of the oxidizing agent / dopant solution of Example 12 measured under the same conditions as in Example 1 was 137 mPa · s.

Example 13
A 40% concentration paratoluenesulfonic acid ferric butanol solution (molar ratio of iron to paratoluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 5.9 g of ethylene glycol diethyl ether and 11.1 g of butanol are added, heated at 60 ° C. for 2 hours, filtered through a glass filter GF75, and the filtrate is subjected to the oxidizing agent of Example 13. Also used as a dopant solution. The calculated solid content of the oxidizing agent / dopant solution of Example 13 was 56.0%, and the amount of ethylene glycol diethyl ether added to ferric paratoluenesulfonate was 9.0%. Further, the viscosity of the oxidizing agent / dopant solution of Example 13 measured under the same conditions as in Example 1 was 129 mPa · s.

Example 14
A 40% concentration paratoluenesulfonic acid ferric butanol solution (molar ratio of iron to paratoluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 8.5 g of ethylene glycol diethyl ether and 8.5 g of butanol were added, heated at 60 ° C. for 2 hours, filtered through a glass filter GF75, and the filtrate was subjected to the oxidizing agent of Example 14. Also used as a dopant solution. The calculated solid concentration of the oxidizing agent / dopant solution of Example 14 was 56.0%, and the amount of ethylene glycol diethyl ether added to ferric paratoluenesulfonate was 13.0%. Moreover, the viscosity measured on the conditions similar to Example 1 of this oxidizing agent and dopant solution of Example 14 was 122 mPa * s.

Example 15
A 40% concentration para-toluenesulfonic acid ferric ethanol solution (molar ratio of iron to para-toluenesulfonic acid 1: 2.75) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. 10.5 g of ethylene glycol diethyl ether and 6.5 g of butanol were added to 100 g of the above solution and heated at 60 ° C. for 2 hours, and filtered through a glass filter GF75. The filtrate was also used as the oxidizing agent of Example 15. A dopant solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 15 was 56.0%, and the amount of ethylene glycol diethyl ether added to ferric paratoluenesulfonate was 16.0%. Moreover, the viscosity measured on the same conditions as Example 1 of this oxidizing agent and dopant solution of Example 15 was 119 mPa * s.

Example 16
A butanol solution (molar ratio of iron to paratoluenesulfonic acid: 1.2.77) was concentrated by distillation with ferric paratoluenesulfonate having a concentration of 40% manufactured by Teika. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 13.1 g of ethylene glycol diethyl ether and 3.9 g of butanol are added, heated at 60 ° C. for 2 hours, filtered through a glass filter GF75, and the filtrate is subjected to the oxidizing agent of Example 16. Also used as a dopant solution. The calculated solid concentration of the oxidizing agent / dopant solution of Example 16 was 56.0%, and the amount of ethylene glycol diethyl ether added to ferric paratoluenesulfonate was 20%. The viscosity of the oxidizing agent / dopant solution of Example 16 measured under the same conditions as in Example 1 was 116 mPa · s.

Example 17
A 40% concentration paratoluenesulfonic acid ferric butanol solution (molar ratio of iron to paratoluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 6.6 g of dibutyl ether [dialkyl ether in which R ¹ and R ² are butyl groups in general formula (1)] and 10.4 g of butanol are added, and heated at 60 ° C. for 2 hours. Then, the mixture was filtered through a glass filter GF75, and the filtrate was used as the oxidizing agent / dopant solution of Example 17. The calculated solid concentration of the oxidizing agent / dopant solution of Example 17 was 56.0%, and the amount of dibutyl ether added to ferric paratoluenesulfonate was 10.0%. Further, the viscosity of the oxidizing agent / dopant solution of Example 17 measured under the same conditions as in Example 1 was 130 mPa · s.

Example 18
A 40% concentration paratoluenesulfonic acid ferric butanol solution (molar ratio of iron to paratoluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 6.6 g of diethylene glycol dimethyl ether [dialkylene glycol dialkyl ether in which R ⁶ and R ⁷ are methyl groups and R ⁸ is ethylene group in general formula (3)] is added, and butanol is 10 After adding 4 g and heating at 60 ° C. for 2 hours, the mixture was filtered through a glass filter GF75, and the filtrate was used as the oxidizing agent / dopant solution of Example 18. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 18 was 56.0%, and the amount of diethylene glycol dimethyl ether added to ferric paratoluenesulfonate was 10.0%. Moreover, the viscosity measured on the conditions similar to Example 1 of the oxidizing agent and dopant solution of this Example 18 was 133 mPa * s.

Comparative Example 5
A 40% concentration paratoluenesulfonic acid ferric butanol solution (molar ratio of iron to paratoluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. 17.0 g of butanol was added to 100 g of the above solution, heated at 60 ° C. for 2 hours, filtered through a glass filter GF75, and the filtrate was used as an oxidizing agent / dopant solution of Comparative Example 5. The calculated solid content concentration of the oxidizing agent / dopant solution of Comparative Example 5 was 56.0%. Moreover, the viscosity measured on the same conditions as Example 1 of the oxidizing agent and dopant solution of this comparative example 5 was 160 mPa * s.

Comparative Example 6
A 40% concentration paratoluenesulfonic acid ferric butanol solution (molar ratio of iron to paratoluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 2.0 g of ethylene glycol diethyl ether and 15.0 g of butanol are added, heated at 60 ° C. for 2 hours, filtered through a glass filter GF75, and the filtrate is an oxidizing agent of Comparative Example 6. Also used as a dopant solution. The calculated solid content concentration of the oxidizing agent / dopant solution of Comparative Example 6 was 56.0%, and the amount of ethylene glycol diethyl ether added to ferric paratoluenesulfonate was 3.0%. Further, the viscosity of the oxidizing agent / dopant solution of Comparative Example 6 measured under the same conditions as in Example 1 was 157 mPa · s.

Comparative Example 7
A 40% concentration paratoluenesulfonic acid ferric butanol solution (molar ratio of iron to paratoluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. When 16.4 g of ethylene glycol diethyl ether was added to 100 g of the above solution, it was separated into two layers, 0.6 g of butanol was further added, and even when heated at 60 ° C. for 2 hours, a uniform oxidizer and dopant No solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Comparative Example 7 was 56.0%, and the amount of ethylene glycol diethyl ether added to ferric paratoluenesulfonate was 25%.

Comparative Example 8
A 40% concentration paratoluenesulfonic acid ferric butanol solution (molar ratio of iron to paratoluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 6.6 g of ethylene glycol monoethyl ether and 10.4 g of butanol are added, heated at 60 ° C. for 2 hours, filtered through a glass filter GF75, and the filtrate is oxidized in Comparative Example 8. An agent / dopant solution was obtained. The calculated solid content concentration of the oxidizing agent / dopant solution of Comparative Example 8 was 56.0%, and the amount of ethylene glycol monomethyl ether added to ferric paratoluenesulfonate was 10.0%. Further, the viscosity of the oxidizing agent / dopant solution of Comparative Example 2 measured under the same conditions as in Example 1 was 160 mPa · s.

  Next, Table 2 shows the addition amount of the dialkyl ether or its derivative of the oxidizing agent / dopant solution of Examples 11 to 18 and Comparative Examples 5 to 8 to the ferric organic sulfonate, the type and viscosity of the dialkyl ether or its derivative. Shown in In addition, about the dialkyl ether or its derivative (s), like the case of Table 1, it simplifies and shows as follows.

EGDE: ethylene glycol diethyl ether DBuE: dibutyl ether DEGPM: diethylene glycol dimethyl ether EGME: ethylene glycol monoethyl ether

  In Table 2, the viscosity of the oxidizing agent / dopant of Comparative Example 7 is not shown because the amount of ethylene glycol diethyl ether added was too large to obtain a uniform oxidizing agent / dopant, so the viscosity was not measured. However, as shown in Table 2, the oxidizers / dopants of Examples 11-18 had lower viscosities than the oxidizers / dopants of Comparative Examples 5-6 and 8.

[Evaluation with solid electrolytic capacitor (1)]
In this [Evaluation with Solid Electrolytic Capacitor (1)], using the oxidant / dopant solution of Examples 1 to 10 prepared as described above, the set capacitance was 100 μF or more and the set ESR was 8 mΩ or less. The wound aluminum solid electrolytic capacitors of Examples 19 to 28 were produced, and the windings of Comparative Examples 9 to 11 produced by using them and the oxidizing agent / dopant solutions of Comparative Examples 1-2 and 4 prepared as described above. The capacitor characteristics of the type aluminum solid electrolytic capacitors were compared, and thereby, the oxidizing agent / dopant solutions of Examples 1 to 10 and Comparative Examples 1 to 2 and 4 used in the production of those wound type aluminum solid electrolytic capacitors were compared. Perform characterization.

Example 19
After etching the surface of the aluminum foil, a lead terminal is attached to the anode formed by the chemical conversion treatment to form the derivative layer, and the lead terminal is attached to the cathode made of the aluminum foil. A capacitor element for producing a wound aluminum solid electrolytic capacitor having a set capacitance of 100 μF or more and a set ESR of 8 mΩ or less was produced by winding through a separator.

  The capacitor element was immersed in a mixed solution prepared by mixing 20 ml of 3,4-ethylenedioxythiophene (manufactured by Teika) and 100 ml of the oxidizing agent / dopant solution of Example 1 and pulled up, then at 70 ° C. Solid electrolyte layer comprising a conductive polymer having 3,4-ethylenedioxythiophene polymer polymerized by polymerizing 3,4-ethylenedioxythiophene by heating at 180 ° C. for 2 hours for 2 hours Formed. This was packaged with an exterior material to produce an aluminum wound solid electrolytic capacitor.

  About the aluminum winding type solid electrolytic capacitor produced as described above, the ESR is measured at 100 kHz and the capacitance is measured at 120 Hz using a LCR meter (4284A) manufactured by HEWLETT PACKARD under the condition of 25 ° C. did. The results are shown in Table 3 below.

Example 20
In place of the oxidant / dopant solution of Example 1, except that the oxidant / dopant solution of Example 2 was used, the same operation as in Example 19 was performed to produce a wound aluminum solid electrolytic capacitor. For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Example 21
In place of the oxidant / dopant solution of Example 1, except that the oxidant / dopant solution of Example 3 was used, the same operation as in Example 19 was performed to produce a wound aluminum solid electrolytic capacitor. For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Example 22
In place of the oxidant / dopant solution of Example 1, except that the oxidant / dopant solution of Example 4 was used, all the same operations as in Example 19 were performed to produce a wound aluminum solid electrolytic capacitor, For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Example 23
In place of the oxidant / dopant solution of Example 1, except that the oxidant / dopant solution of Example 5 was used, the same operation as in Example 19 was performed to produce a wound aluminum solid electrolytic capacitor. For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Example 24
In place of the oxidant / dopant solution of Example 1, except that the oxidant / dopant solution of Example 6 was used, the same operation as in Example 19 was performed to produce a wound aluminum solid electrolytic capacitor. For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Example 25
In place of the oxidant / dopant solution of Example 1, except that the oxidant / dopant solution of Example 7 was used, the same operation as in Example 19 was performed to produce a wound aluminum solid electrolytic capacitor. For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Example 26
Instead of the oxidizing agent / dopant solution of Example 1, except that the oxidizing agent / dopant solution of Example 8 was used, all the same operations as in Example 19 were performed to produce a wound aluminum solid electrolytic capacitor, For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Example 27
In place of the oxidant / dopant solution of Example 1, except that the oxidant / dopant solution of Example 9 was used, the same operation as in Example 19 was performed to produce a wound aluminum solid electrolytic capacitor. For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Example 28
In place of the oxidant / dopant solution of Example 1, except that the oxidant / dopant solution of Example 10 was used, all the same operations as in Example 19 were performed to produce a wound aluminum solid electrolytic capacitor, For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Comparative Example 9
In place of the oxidant and dopant solution of Example 1, except that the oxidant and dopant solution of Comparative Example 1 was used, all the same operations as in Example 19 were performed to produce a wound aluminum solid electrolytic capacitor. For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Comparative Example 10
In place of the oxidant / dopant solution of Example 1, except that the oxidant / dopant solution of Comparative Example 2 was used, all the same operations as in Example 19 were performed to produce a wound aluminum solid electrolytic capacitor, For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

Comparative Example 11
In place of the oxidant / dopant solution of Example 1 except that the oxidant / dopant solution of Comparative Example 4 was used, the same operation as in Example 19 was performed to produce a wound aluminum solid electrolytic capacitor. For this wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 19. The results are shown in Table 3 below.

  The oxidizing agent / dopant solution in which the capacitances and ESRs of the wound aluminum solid electrolytic capacitors of Examples 19 to 28 and Comparative Examples 9 to 11 prepared as described above were used for the production of the wound aluminum solid electrolytic capacitor. It shows in following Table 3 with the kind of.

  As shown in Table 3, the wound aluminum solid electrolytic capacitors of Examples 19 to 28 have a capacitance of 103.5 to 105.9 μF, satisfy a set capacitance of 100 μF or more, and have an ESR of 7 mΩ. Although it was a stand and met the set ESR of 8 mΩ or less, the wound aluminum solid electrolytic capacitors of Comparative Examples 9 to 11 did not reach the capacitance of 100 μF and did not satisfy the capacitance of 100 μF or more. The ESR exceeded 8 mΩ and did not satisfy the set ESR of 8 mΩ or less.

  That is, the windings of Examples 19 to 28 prepared using the oxidizing agent and dopant solution of Examples 1 to 10 in which a dialkyl ether or a derivative thereof was added in a predetermined range to ferric organic sulfonate as an oxidizing agent and dopant. The rotary aluminum solid electrolytic capacitor was produced using the oxidizing agent / dopant solution of Comparative Example 1 which had a large capacitance, low ESR, and excellent capacitor characteristics but did not contain a dialkyl ether or its derivative. The rolled aluminum solid electrolytic capacitor of Comparative Example 10 produced using the wound aluminum solid electrolytic capacitor of Comparative Example 9 and the oxidizing agent / dopant solution of Comparative Example 2 with a small addition amount of ethylene glycol dimethyl ether belonging to the dialkyl ether derivative. Instead of solid electrolytic capacitors, dialkyl ethers or their derivatives, The wound aluminum solid electrolytic capacitor of Comparative Example 11 produced using the oxidizing agent / dopant solution of Comparative Example 4 prepared by adding an alkyl-based ethylene glycol monomethyl ether is the wound aluminum of Examples 19 to 28. Compared with the solid electrolytic capacitor, the capacitance was small, the ESR was large, and the capacitor characteristics were inferior.

  And from this result, the oxidizing agent / dopant solution of Examples 1 to 10 used in the production of the wound aluminum solid electrolytic capacitors of Examples 19 to 28 is the wound aluminum solid electrolytic capacitor of Comparative Examples 9 to 11. From the oxidant / dopant solutions of Comparative Examples 1-2 and 4 used in the preparation of the above, it can be seen that the characteristics are excellent as an oxidant / dopant solution for producing a conductive polymer, and Examples 1 to 10 It can be seen that the conductive polymer produced by oxidative polymerization of 3,4-ethylenedioxythiophene using the above oxidant / dopant solution has excellent characteristics.

[Evaluation with solid electrolytic capacitor (2)]
In this [Evaluation with Solid Electrolytic Capacitor (2)], using the oxidant / dopant solutions of Examples 11 to 18 prepared as described above, the set capacitance was 50 μF or more and the set ESR was 12 mΩ or less. The wound aluminum solid electrolytic capacitors of Examples 29 to 36 were produced, and the windings of Comparative Examples 12 to 14 produced using them and the oxidizing agent / dopant solutions of Comparative Examples 5 to 6 and 8 prepared as described above. Comparison of capacitor characteristics with type aluminum solid electrolytic capacitors, and thereby, of the oxidizing agents and dopants of Examples 11 to 18 and Comparative Examples 5 to 6 and 8 used in the production of those wound type aluminum solid electrolytic capacitors Perform characterization.

Example 29
After etching the surface of the aluminum foil, a lead terminal is attached to the anode formed by the chemical conversion treatment to form the derivative layer, and the lead terminal is attached to the cathode made of the aluminum foil. A capacitor element for producing a wound aluminum solid electrolytic capacitor having a set electrostatic capacity of 50 μF or more and a set ESR of 12 mΩ or less was wound through a separator.

  The capacitor element was immersed in a monomer solution prepared by adding 80 ml of methanol to 20 ml of 3,4-ethylenedioxythiophene (manufactured by Teika), pulled up, and then dried at 50 ° C. for 10 minutes. Thereafter, the capacitor element was immersed in 500 ml of the oxidant / dopant solution of Example 11 and pulled up, and then heated at 70 ° C. for 2 hours and at 180 ° C. for 1 hour, thereby producing the monomer 3,4-ethylenedioxythiophene. Was polymerized to form a solid electrolyte layer made of a conductive polymer having a polymer backbone of 3,4-ethylenedioxythiophene polymer. This was covered with an exterior material to produce a wound aluminum solid electrolytic capacitor.

  For the wound aluminum solid electrolytic capacitor produced as described above, the ESR is measured at 100 kHz and the capacitance is measured at 120 Hz using a LCR meter (4284A) manufactured by HEWLETT PACKARD under the condition of 25 ° C. did. The results are shown in Table 4 below.

Example 30
Instead of the oxidizing agent / dopant solution of Example 11, except that the oxidizing agent / dopant solution of Example 12 was used, all the same operations as in Example 29 were performed to produce a wound aluminum solid electrolytic capacitor, For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

Example 31
Instead of the oxidizing agent / dopant solution of Example 11, except that the oxidizing agent / dopant solution of Example 13 was used, all the same operations as in Example 29 were performed to produce a wound aluminum solid electrolytic capacitor, For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

Example 32
Instead of the oxidizing agent / dopant solution of Example 11, except that the oxidizing agent / dopant solution of Example 14 was used, the same operation as in Example 29 was performed to produce a wound aluminum solid electrolytic capacitor, For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

Example 33
A wound aluminum solid electrolytic capacitor was produced by performing the same operation as in Example 29 except that the oxidant / dopant solution of Example 15 was used instead of the oxidant / dopant solution of Example 11. For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

Example 34
Instead of the oxidizing agent / dopant solution of Example 11, except for using the oxidizing agent / dopant solution of Example 16, all the same operations as in Example 29 were performed to produce a wound aluminum solid electrolytic capacitor, For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

Example 35
Instead of the oxidizing agent / dopant solution of Example 11, except that the oxidizing agent / dopant solution of Example 17 was used, all the same operations as in Example 29 were performed to produce a wound aluminum solid electrolytic capacitor, For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

Example 36
Instead of the oxidizing agent / dopant solution of Example 11, except that the oxidizing agent / dopant solution of Example 18 was used, all the same operations as in Example 29 were performed to produce a wound aluminum solid electrolytic capacitor, For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

Comparative Example 12
A wound aluminum solid electrolytic capacitor was produced by performing the same operation as in Example 29 except that the oxidant and dopant solution of Comparative Example 5 was used instead of the oxidant and dopant solution of Example 11. For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

Comparative Example 13
Instead of the oxidant and dopant solution of Example 11, except that the oxidant and dopant solution of Comparative Example 6 was used, all the same operations as in Example 29 were performed to produce a wound aluminum solid electrolytic capacitor, For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

Comparative Example 14
A wound aluminum solid electrolytic capacitor was produced by performing the same operation as in Example 29 except that the oxidant / dopant solution of Comparative Example 8 was used instead of the oxidant / dopant solution of Example 11. For the wound aluminum solid electrolytic capacitor, ESR and capacitance were measured in the same manner as in Example 29. The results are shown in Table 4 below.

  The capacitance and ESR of the wound aluminum solid electrolytic capacitors of Examples 29 to 36 and Comparative Examples 12 to 14 are as follows along with the type of the oxidant / dopant solution used in the production of the wound aluminum solid electrolytic capacitor: Table 4 shows.

  As shown in Table 4, the wound aluminum solid electrolytic capacitors of Examples 29 to 36 have a capacitance of 50.6 to 52.4 μF, satisfy a set capacitance of 50 μF or more, and have an ESR of 11 mΩ. Although it was a table and met the set ESR of 12 mΩ or less, the wound aluminum solid electrolytic capacitors of Comparative Examples 12 to 14 did not reach the capacitance of 50 μF and did not satisfy the set capacitance of 50 μF or more. The ESR exceeded 12 mΩ and did not satisfy the set ESR of 12 mΩ or less.

  That is, the windings of Examples 29 to 36 prepared using the oxidizing agent and dopant solution of Examples 11 to 18 in which a dialkyl ether or a derivative thereof was added in a predetermined range to ferric organic sulfonic acid and dopant. The rotary aluminum solid electrolytic capacitor was produced using the oxidizing agent / dopant solution of Comparative Example 5 which had a large capacitance, low ESR, and excellent capacitor characteristics but did not contain a dialkyl ether or its derivative. The wound aluminum solid electrolytic capacitor of Comparative Example 12 and the wound type of Comparative Example 13 fabricated using the oxidizing agent / dopant solution of Comparative Example 6 with a small amount of ethylene glycol diethyl ether belonging to the derivative of dialkyl ether were added. Instead of aluminum solid electrolytic capacitors, dialkyl ethers or their derivatives The wound aluminum solid electrolytic capacitor of Comparative Example 14 produced using the oxidizing agent / dopant solution of Comparative Example 8 to which monoalkyl ethylene glycol monoethyl ether was added is the wound aluminum solid capacitor of Examples 29 to 36. Compared with the electrolytic capacitor, the capacitance was small, the ESR was large, and the capacitor characteristics were inferior.

  And from this result, the oxidizing agent / dopant solutions of Examples 11 to 18 used in the production of the wound aluminum solid electrolytic capacitors of Examples 29 to 36 are the wound aluminum solid electrolytic capacitors of Comparative Examples 12 to 14. From the oxidant / dopant solutions of Comparative Examples 5 to 6 and 8 used in the preparation of the above, it can be seen that the characteristics are excellent as an oxidant / dopant solution for producing a conductive polymer, and Examples 11 to 18 It can be seen that the conductive polymer produced by oxidative polymerization of 3,4-ethylenedioxythiophene using the above oxidant / dopant solution has excellent characteristics.

Further, in the production of the solid electrolytic capacitor, when the capacitor element is immersed in the mixture of the oxidant / dopant solution of the present invention and the monomer, the oxidant / dopant solution of the present invention is usually prepared in advance. Mixing with monomer, but without preparing in advance, mixing organic solvent solution of ferric organic sulfonate (organic solvent solution having hydroxyl group), dialkyl ether or its derivative, and monomer Then, in such a mixed state, an organic solvent solution of ferric organic sulfonate corresponding to the oxidizing agent / dopant solution of the present invention and a dialkyl ether or a derivative thereof may be present.

Example 11
A 40% concentration paratoluenesulfonic acid ferric butanol solution (molar ratio of iron to paratoluenesulfonic acid 1: 2.77) manufactured by Teika was concentrated by distillation. The dry solid content of this solution was 65.5%. To 100 g of the above solution, 6.6 g of ethylene glycol diethyl ether [alkylene glycol dialkyl ether in which R ³ and R ⁴ are ethyl groups and R ⁵ is an ethylene group in the general formula (2)] is added, and butanol is added. 10.4 g was added and heated at 60 ° C. for 2 hours, and then filtered through a glass filter GF75, and the filtrate was used as the oxidizing agent / dopant solution of Example 11. The calculated solid content concentration of the oxidizing agent / dopant solution of Example 11 was 56.0%, and the amount of ethylene glycol diethyl ether added to ferric paratoluenesulfonate was 10.0%. In addition, the viscosity of the oxidizing agent / dopant solution of Example 11 measured under the same conditions as in Example 1 was 127 mPa · s.

First, the capacitor element of a wound-type aluminum solid electrolytic capacitor, after the surface of the aluminum foil was etched, attach the lead terminals to the anode forming the induction conductor layer by chemical conversion treatment, also made of an aluminum foil cathode A lead terminal is attached to the electrode, and those prepared by winding the anode and cathode with the lead terminal through a separator are used.

In the production of solid electrolytic capacitors other than the above wound aluminum solid electrolytic capacitors, for example, laminated aluminum solid electrolytic capacitors, tantalum solid electrolytic capacitors, niobium solid electrolytic capacitors, etc., valve metals such as aluminum, tantalum, and niobium as capacitor elements an anode comprising a porous body, using those with induced conductor layer made of an oxide film of their valve metal, the capacitor element, as in the case of the winding type aluminum solid electrolytic capacitor, the oxidation of the present invention After dipping in a mixture of the agent / dopant solution and the monomer and pulling it up to polymerize the monomer (thiophene or its derivative) at room temperature or under heating, or dipping the capacitor element into the monomer solution and pulling it up and drying, The capacitor element is used as the oxidizing agent / dopa of the present invention Dipping in the solution and pulling up to polymerize the monomer at room temperature or under heating, or immersing the capacitor element in the oxidizing agent / dopant solution of the present invention and pulling it up, and then immersing the capacitor element in the monomer. After pulling up, the monomer is polymerized at room temperature or under heating, and these steps are repeated to form a solid electrolyte layer made of a conductive polymer, and then a carbon paste and a silver paste are attached, dried, and then packaged. Thus, a laminated aluminum solid electrolytic capacitor, a tantalum solid electrolytic capacitor, a niobium solid electrolytic capacitor, and the like are produced.

Example 19
After the surface of the aluminum foil was etched, attach the lead terminals to the anode forming the induction conductor layer by performing a chemical conversion treatment, also attach the lead terminals to the cathode made of an aluminum foil, those lead terminals with an anode and a cathode Were wound through a separator to produce a capacitor element for producing a wound aluminum solid electrolytic capacitor having a set capacitance of 100 μF or more and a set ESR of 8 mΩ or less.

Example 29
After the surface of the aluminum foil was etched, attach the lead terminals to the anode forming the induction conductor layer by performing a chemical conversion treatment, also attach the lead terminals to the cathode made of an aluminum foil, those lead terminals with an anode and a cathode Were wound through a separator to produce a capacitor element for producing a wound aluminum solid electrolytic capacitor having a set capacitance of 50 μF or more and a set ESR of 12 mΩ or less.

Claims (10)

  An oxidizing agent / dopant solution for producing a conductive polymer comprising ferric organic sulfonate as an oxidizing agent / dopant for producing a conductive polymer and an organic solvent having a hydroxyl group, comprising a dialkyl ether or a derivative thereof An oxidizing agent / dopant solution for producing a conductive polymer, wherein 4 to 20% by mass is added to the ferric organic sulfonate. A dialkyl ether or a derivative thereof is a dialkyl ether represented by the following general formula (1), an alkylene glycol dialkyl ether represented by the general formula (2) and a dialkylene glycol dialkyl ether represented by the general formula (3). The oxidizing agent / dopant solution for producing a conductive polymer according to claim 1, which is at least one selected from the group consisting of:
General formula (1):
R ¹ —O—R ²
(In the formula, R ¹ and R ² are each an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and these R ¹ and R ² may be the same or different from each other, provided that R ¹ is different. And R ² are simultaneously CH ₃ )
General formula (2):
R ³ —O—R ⁵ —O—R ⁴
(In the formula, R ³ and R ⁴ are aliphatic hydrocarbon groups having 1 to ⁴ carbon atoms, and these R ³ and R ⁴ may be the same or different from each other. R ⁵ is carbon. (It is an alkylene group having a number of 1 to 3.)
General formula (3):
R ⁶ —O— (R ⁸ —O) ₂ —R ⁷
(In the formula, R ⁶ and R ⁷ are aliphatic hydrocarbon groups having 1 to 4 carbon atoms, and these R ⁶ and R ⁷ may be the same or different from each other. R ⁸ is carbon. (It is an alkylene group having a number of 1 to 3.)   The oxidant / dopant solution for producing a conductive polymer according to claim 1 or 2, wherein the organic solvent having a hydroxyl group is an alcohol having 1 to 4 carbon atoms.   The oxidant / dopant solution for producing a conductive polymer according to any one of claims 1 to 3, wherein the ferric organic sulfonate is ferric paratoluenesulfonate.   The oxidant and dopant solution for producing a conductive polymer according to any one of claims 1 to 4, wherein the molar ratio of the organic sulfonic acid to iron in the ferric organic sulfonate is less than 1: 3.   The concentration of the ferric organic sulfonate is 55% by mass or more. The oxidizing agent / dopant solution for producing a conductive polymer according to any one of claims 1 to 5.   A conductive polymer produced by oxidative polymerization of thiophene or a derivative thereof using the oxidizing agent / dopant solution for producing a conductive polymer according to any one of claims 1 to 6.   A conductive polymer produced by oxidative polymerization of thiophene or a derivative thereof using the oxidizing agent / dopant solution for producing a conductive polymer according to any one of claims 1 to 6 is used as a solid electrolyte. Solid electrolytic capacitor.   A conductive polymer is produced by oxidative polymerization of thiophene or a derivative thereof using the oxidant / dopant solution for producing a conductive polymer according to any one of claims 1 to 6. A method for producing a solid electrolytic capacitor, comprising producing a solid electrolytic capacitor by using as a solid electrolyte.   10. The oxidant / dopant solution for producing a conductive polymer is obtained by adding a dialkyl ether or a derivative thereof to an organic solvent solution having a hydroxyl group of ferric organic sulfonate at the time of producing a solid electrolytic capacitor. Manufacturing method for solid electrolytic capacitor.