JP2014225538A - Oxidant solution for manufacturing conductive polymer, and method for manufacturing solid electrolytic capacitor by use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxidant solution for manufacturing a conductive polymer which makes it possible to manufacture a solid electrolytic capacitor superior in high electrostatic capacitance and low ESR, and having heat resistance; a solid electrolytic capacitor produced by use of such an oxidant solution; and a method for manufacturing such a solid electrolytic capacitor.SOLUTION: An oxidant solution comprises an organic ferric sulfonate salt serving as an oxidant. The organic ferric sulfonate salt includes, as an organic sulfonic acid, an alkylbenzene sulfonic acid expressed by the general formula (1), and a benzene sulfonic acid expressed by the general formula (2) in a particular proportion. A solid electrolytic capacitor superior in high electrostatic capacitance and low ESR and having heat resistance comprises a conductive polymer formed by use of the oxidant solution. A method for manufacturing such a solid electrolytic capacitor comprises: using the oxidant solution.

Description

  The present invention relates to an oxidant solution for producing a conductive polymer, and more specifically, used when forming a conductive polymer layer suitable as a solid electrolyte of a solid electrolytic capacitor, and has a high capacity and low equivalent series resistance (hereinafter referred to as “ESR”). It is related with the oxidizing agent solution for conductive polymer manufacture which contributes to manufacture of the solid electrolytic capacitor which shows. Furthermore, it is related with the solid electrolytic capacitor which uses this oxidizing agent solution, and its manufacturing method.

  Since the conductive polymer has high conductivity, it is useful as a solid electrolyte such as an aluminum electrolytic capacitor and a tantalum electrolytic capacitor.

  Examples of the conductive polymer include those obtained by chemical oxidative polymerization or electrolytic oxidative polymerization of a polymerizable monomer such as pyrrole or a derivative thereof or thiophene or a derivative thereof.

  An organic sulfonic acid is mainly used as a dopant in the chemical oxidative polymerization of the pyrrole or its derivative or thiophene or its derivative, and among them, it is known to use an aromatic sulfonic acid. Further, transition metal salts of these aromatic sulfonic acids are used as the oxidizing agent for polymerization, and among these, it is known to use ferric salts.

  For example, Patent Document 1 discloses that a conductive polymer layer formed by polymerizing a polymerizable monomer using p-toluenesulfonic acid ferric salt, which is an aromatic sulfonic acid ferric salt, as a solid agent is solid. A capacitor as an electrolyte is disclosed.

  Further, Cited Document 2 discloses a solid electrolytic capacitor manufactured using an alcohol solution containing ferric toluenesulfonate or ferric methoxybenzenesulfonate and ferric sulfate as an oxidant and dopant. Yes. However, this solid electrolytic capacitor also does not have sufficient electrostatic capacity and ESR, and these changes are large under high temperature conditions and inferior in heat resistance.

Japanese Patent Laid-Open No. 02-015611 No. 2009-001707

  Accordingly, there is a need for a solid electrolytic capacitor having high capacitance, low ESR and excellent heat resistance, and the present invention provides an oxidation for producing a conductive polymer capable of obtaining such a solid electrolytic capacitor. It is an object to provide a chemical solution.

  As a result of intensive studies to solve the above problems, the present inventor, as an organic sulfonic acid contained in an organic sulfonic acid ferric salt that is an oxidizing agent, an alkylbenzene sulfonic acid represented by the general formula (1), By forming a conductive polymer using an oxidant solution in which a specific amount of the benzenesulfonic acid represented by the general formula (2) is combined, a high capacitance, a low ESR, and an excellent heat resistance thereof. The present inventors have found that a solid electrolytic capacitor having can be obtained and completed the present invention.

  That is, the present invention is as follows.

The first invention is an oxidizing agent solution for producing a conductive polymer containing an organic sulfonic acid ferric salt in a solvent, and as an organic sulfonic acid contained in the organic sulfonic acid ferric salt,
The alkylbenzene sulfonic acid represented by the following general formula (1) and the benzene sulfonic acid represented by the following general formula (2) are contained, and the alkylbenzene sulfonic acid represented by the general formula (1) with respect to the whole organic sulfonic acid is contained. The amount is 60 to 99 mol%, the content of benzenesulfonic acid represented by the general formula (2) is 1 to 40 mol%, and an alcohol solvent is the main solvent. It is an oxidant solution.

（式（１）中、Ｒ_１は炭素数１〜４のアルキル基を示し、Ｒ_２は水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、ヒドロキシ基のいずれかを示す。ｎは１又は２の整数である。）

(In the formula (1), _{R 1} represents an alkyl group having 1 to 4 carbon atoms, _{R 2} is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a hydroxy group N is an integer of 1 or 2.)

  A second invention is the oxidant solution for producing a conductive polymer according to the first invention, wherein the benzenesulfonic acid represented by the general formula (2) is sulfosalicylic acid.

  In the third invention, the alcohol solvent is one or more selected from the group consisting of methanol, ethanol and butanol. For producing a conductive polymer according to the first or second invention, It is an oxidant solution.

  A fourth invention is the oxidant solution for producing a conductive polymer according to any one of the first to third inventions, wherein the water content is less than 5% by mass.

  A fifth invention is a conductive polymer formed by a chemical oxidative polymerization reaction of a polymerizable monomer using the oxidant solution for producing a conductive polymer according to any one of the first to fourth inventions. It is a solid electrolytic capacitor characterized by having a layer.

  According to a sixth aspect of the present invention, a polymerizable monomer and an oxidizing agent solution are impregnated in a capacitor element, or a polymerizable monomer solution and an oxidizing agent solution are impregnated in a capacitor element, whereby a polymerizable monomer and an oxidizing agent are oxidized. In the method for producing a solid electrolytic capacitor including the step of forming a conductive polymer layer on the capacitor element by causing a chemical oxidative polymerization reaction of the agent, the oxidant solution is any one of the first to fourth inventions. A solid electrolytic capacitor manufacturing method using an oxidizing agent solution for manufacturing a conductive polymer.

  The solid electrolytic capacitor produced by using the oxidant solution for producing a conductive polymer of the present invention exhibits high electrostatic capacity, low ESR, and excellent heat resistance.

(Oxidant solution for conductive polymer production)
The oxidant solution for producing a conductive polymer of the present invention (hereinafter sometimes simply referred to as “oxidant solution”) is represented by the following general formula (1) as an organic sulfonic acid ferric salt of an oxidant. Contains alkylbenzene sulfonic acid and ferric salt of benzene sulfonic acid.
The oxidant solution for producing a conductive polymer of the present invention is an oxidant solution for producing a conductive polymer containing an organic sulfonic acid ferric salt in a solvent, and is contained in the organic sulfonic acid ferric salt. As an organic sulfonic acid, it contains an alkylbenzene sulfonic acid represented by the following general formula (1) and a benzene sulfonic acid represented by the following general formula (2), and is represented by the general formula (1) for the whole organic sulfonic acid. The content of the alkylbenzene sulfonic acid is 60 to 99 mol%, the content of the benzenesulfonic acid represented by the general formula (2) is 1 to 40 mol%, and an alcohol solvent is the main solvent. It is an oxidizing agent solution for manufacturing a conductive polymer.

In general formula (1), R ₁ represents an alkyl group having 1 to 4 carbon atoms.

  Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, propyl group, butyl group, isopropyl group, and isobutyl group.

  Specific examples of the alkylbenzenesulfonic acid represented by the general formula (1) include p-toluenesulfonic acid, p-ethylbenzenesulfonic acid, p-propylbenzenesulfonic acid, p-butylbenzenesulfonic acid, and p-isopropylbenzenesulfonic acid. , P-isobutylbenzenesulfonic acid. Among these, p-toluenesulfonic acid is preferable because it has a high polymerization rate.

In General Formula (2), R ₂ represents any of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a hydroxy group. n is an integer of 1 or 2. From the viewpoint of heat resistance in the electrical characteristics of the solid electrolytic capacitor, n is more preferably 1.

  Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, propyl group, butyl group, isopropyl group, and isobutyl group.

  Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

  Among these, a hydroxy group is preferable because it improves the heat resistance of the solid electrolytic capacitor.

  Specific examples of the benzenesulfonic acid represented by the general formula (2) include p-carboxybenzenesulfonic acid, m-carboxybenzenesulfonic acid, o-carboxybenzenesulfonic acid, carboxybenzene, and 4-methyl-3-carboxybenzene. Sulfonic acid, 4-ethyl-3carboxybenzenesulfonic acid, 5-methyl-3carboxybenzenesulfonic acid, 5-ethyl-3-carboxybenzenesulfonic acid, 1-methyl-5-carboxybenzenesulfonic acid, 1-ethyl-5 Examples thereof include carboxybenzene sulfonic acid, 4-sulfoisophthalic acid, and 5-sulfosalicylic acid. Among these, 5-sulfosalicylic acid is preferable because it particularly improves the heat resistance of the solid electrolytic capacitor.

The oxidizing agent solution of the present invention is 60 to 99 mol%, preferably 70 to 95, alkylbenzenesulfonic acid represented by the general formula (1) with respect to the whole organic sulfonic acid contained in the organic sulfonic acid ferric salt. The benzenesulfonic acid represented by the general formula (2) is contained in an amount of 1 to 40 mol%, preferably 5 to 30 mol%, more preferably 10 to 10 mol%. It contains 20 mol%.
The molar ratio of the alkylbenzenesulfonic acid represented by the general formula (1) and the benzenesulfonic acid represented by the general formula (2) is preferably 99: 1 to 60:40, and 95: 5 to 70. : 30 is more preferable, and 90:10 to 80:20 is particularly preferable. If it is such a range, the solid electrolytic capacitor which has sufficiently high electrostatic capacity, low ESR, and those outstanding heat resistance can be obtained.

  The molar ratio of the organic sulfonate anion and the ferric cation composed of the alkylbenzene sulfonate anion represented by the general formula (1) and the benzene sulfonate anion represented by the general formula (2) is not particularly limited. Is preferably 2.00 to 3.50: 1, more preferably 2.50 to 3.30: 1, and particularly preferably 2.95 to 3.20: 1. By setting the molar ratio in such a range, a conductive polymer layer having more excellent heat resistance can be formed.

  The contents of the alkylbenzenesulfonic acid represented by the general formula (1) and the ferric salt of the benzenesulfonic acid represented by the general formula (2) in the oxidizing agent solution of the present invention are not particularly limited, but a total of 30 The range of -80 mass% is preferable, and 40-70 mass% is more preferable. If it is out of this range, the capacity appearance rate may be inferior.

  The solvent used for the oxidizing agent solution of the present invention is an alcohol solvent as a main solvent. Examples of the alcohol solvent include lower alcohols having 1 to 5 carbon atoms such as methanol, ethanol, propanol, isopropanol, butanol, and amyl alcohol, which can be used alone or in combination of two or more. Among these, even when the organic sulfonic acid ferric salt is contained at a high concentration of, for example, 60% by mass or more, it has excellent storage stability, so methanol, ethanol, butanol, and a mixed solvent of two or more of these In particular, a mixed solvent of butanol and methanol and a mixed solvent of butanol and ethanol are preferable. In these mixed solvents, the mass ratio of butanol and methanol or ethanol is preferably 80:20 to 20:80, and more preferably 60:40 to 40:60. Within this range, the polymerization rate is optimized, which is preferable in that a solid electrolytic capacitor having more excellent electrical characteristics can be produced.

  In addition to the alcohol solvent, a secondary solvent can be added to the solvent to the extent that storage stability is not impaired. Examples of the co-solvent include ethers such as diethyl ether, dipropyl ether, and dibutyl ether, ketones such as acetone and methyl ethyl ketone, and glycols such as ethylene glycol and propylene glycol.

  Content of the alcohol solvent in a solvent is 50 mass% or more, Preferably it is 60 mass% or more. Within this range, the impregnation property with respect to the valve metal having a dielectric oxide film is increased, and thus a solid electrolytic capacitor having better ESR can be preferably produced.

  In general, it is known that in the formation of the conductive polymer layer, the ESR of the solid electrolytic capacitor can be reduced by improving the polymerization efficiency of the polymerizable monomer and increasing the electrical conductivity of the conductive polymer layer. (Patent Document 2) By adjusting the amount of water contained in the oxidant solution of the present invention within a certain range, the polymerization rate can be appropriately controlled and the polymerization efficiency can be improved. The water content in the oxidant solution is preferably less than 5% by mass, more preferably 0.01 to 4% by mass, and particularly preferably 0.1 to 3% by mass. When the water content is 5% by mass or more, the polymerization efficiency may decrease.

  Next, the manufacturing method of the oxidizing agent solution for conductive polymer manufacture of this invention is demonstrated.

  Add ferric oxide to the aqueous solution of alkylbenzenesulfonic acid represented by general formula (1) and benzenesulfonic acid represented by general formula (2), and after stirring, remove unreacted iron oxide and impurities by filtration. Then, water is removed to obtain the desired alkylbenzene sulfonic acid and ferric salt of benzene sulfonic acid. The concentration of the organic sulfonic acid in the aqueous solution used for the reaction is arbitrary, but is preferably adjusted to a concentration of 50 to 80% by mass. Further, iron oxide is added in an equivalent amount to the alkylbenzenesulfonic acid represented by the general formula (1) and the benzenesulfonic acid represented by the general formula (2). Usually, by reacting at 100 to 120 ° C. for 5 to 72 hours, the target alkylbenzene sulfonic acid represented by general formula (1) and ferric iron of benzene sulfonic acid represented by general formula (2) A salt can be formed.

  After completion of the reaction, the obtained reaction solution is filtered, and the filtrate is concentrated and dehydrated. During the dehydration step, butanol or the like as the solvent of the oxidant solution is added and concentrated, and then the alkylbenzene sulfonic acid represented by the general formula (1) and the ferric iron of the benzene sulfonic acid represented by the general formula (2) The salt concentration can be adjusted. Further, during the dehydration step, a low-boiling solvent such as an ether compound may be added and dehydrated while azeotropically forming a mixture of water, alcohol and ether compound. By repeating this dehydration step a plurality of times, the water content in the oxidant solution can be adjusted to a desired range.

(Solid electrolytic capacitor)
Next, a solid electrolytic capacitor produced using the oxidant solution of the present invention and a method for producing the same will be described.

  Taking the case of a wound capacitor as an example, first, a strip-shaped anode foil in which an oxide film is formed on the surface of a valve metal made of aluminum, tantalum, niobium, titanium, etc., and a metal strip-shaped cathode foil serving as a counter cathode, A capacitor element having a winding portion prepared by winding a wire through a strip-shaped insulating separator is prepared.

  The winding portion of the capacitor element is impregnated with the mixed solution of the oxidant solution and the polymerizable monomer of the present invention, subjected to a chemical oxidative polymerization reaction in the capacitor element, and appropriately dried, whereby the capacitor element has a high conductivity. A molecular layer is formed. When impregnating the capacitor element portion, the polymerizable monomer solution and the oxidant solution may be impregnated without mixing the polymerizable monomer and the oxidant solution. This impregnation and drying process may be repeated.

  As the polymerizable monomer, a thiophene-based conductive polymer material, a pyrrole-based or aniline-based conductive polymer material is used, and 3,4-ethylenedioxythiophene is more preferably used.

  The polymerization reaction is usually carried out at 45 to 150 ° C., and the reaction time is 0.5 to 5 hours. After the polymerization, washing may be performed in order to remove a polymerization residue, an excess polymerizable monomer, and an oxidizing agent. Then, it encloses in a metal case and performs a process such as aging as necessary to complete a wound capacitor.

  Next, a case of a chip capacitor will be described as an example. A plate-like foil or sintered body of valve action metal such as aluminum, tantalum, niobium or titanium is prepared, and an anode body is prepared by oxidizing the surface of the anode body to form a dielectric oxide film. A conductive polymer layer, a carbon layer containing conductive carbon, and a cathode lead layer made of silver paste or the like are sequentially formed on the anode body to constitute a capacitor element. In forming the conductive polymer layer on the anode body, the polymerization reaction may be carried out using the oxidant solution of the present invention in the same manner as in the case of the wound capacitor. The anode terminal is connected to the anode lead member planted on one end surface of the anode body, the cathode terminal is connected to the cathode lead-out layer, and the capacitor element is covered and sealed with an exterior resin such as an epoxy resin to complete the chip capacitor. .

  The solid electrolytic capacitor of the present invention thus obtained has a high electrostatic capacity, low ESR, small fluctuations after exposure to high temperatures for a long time, and extremely high heat resistance. The capacity is preferably 580 μF or more, more preferably 600 μF or more, and the initial ESR is preferably 7.0 mΩ or less, more preferably 6.5 mΩ or less.

  The reason for this is not clear, but the benzenesulfonic acid represented by the general formula (2) has a carboxyl group and therefore has better wettability than the alkylbenzenesulfonic acid represented by the general formula (1). It can be immersed in the pores of the valve metal. As a result, the obtained solid electrolytic capacitor can have a high electrostatic capacity and a low ESR, and desorption does not easily occur as a dopant, so that heat resistance is considered to be improved.

  Hereinafter, the present invention will be described in more detail based on examples and the like. In addition, this invention is not limited at all by these Examples.

(Production Example 1)
Preparation of oxidant solution:
p-Toluenesulfonic acid monohydrate (Wako Pharmaceutical) 50.0 g, 5-sulfosalicylic acid dihydrate (Wako Pharmaceutical) 0.67 g (molar ratio of p-toluenesulfonic acid and 5-sulfosalicylic acid = 99: 1 3.28 g of water was added to 7.), and 7.60 g of ferric oxide was mixed with stirring, and the mixture was refluxed with stirring at a temperature of 100 ° C. for 3 hours. Thereafter, water was distilled off, and 50 ml of a mixed solvent of butanol and methanol (mass ratio 1: 1) was added. About the obtained butanol / methanol mixed solution of the ferric salt of p-toluenesulfonic acid and sulfosalicylic acid, the concentration of the ferric salt of p-toluenesulfonic acid and sulfosalicylic acid was titrated with 0.1N sodium thiosulfate aqueous solution. Then, a mixed solution of butanol and methanol (mass ratio 1: 1) was added so that the total concentration of these was 60% by mass to prepare an oxidant solution (oxidant solution 1). Moreover, it was 1.0 mass% when the water content in the oxidizing agent solution was measured by the Karl Fischer method.

(Production Examples 2 to 6)
An oxidizer solution was prepared in the same manner as in Production Example 1 except that the addition amounts of p-toluenesulfonic acid and 5-sulfosalicylic acid relative to the whole organic sulfonic acid were changed to the values shown in Table 1. (Oxidant solutions 2-6). When water content was measured in the same manner as in Production Example 1 for each oxidant solution, it was 1.0% by mass.

(Production Examples 7 to 9)
Instead of the salicylic acid used in Production Example 1, the organic sulfonic acid described in Table 1 was contained, and the addition amount was changed so as to obtain the content corresponding to Table 1, respectively. An oxidant solution was prepared (oxidant solutions 7 to 9). When the water content was measured in the same manner as in Production Example 1 for each oxidant solution, it was 1.0% by mass.

(Comparative Production Examples 1 and 2)
An oxidant solution was prepared in the same manner as in Production Example 1 except that the respective addition amounts were changed so that the contents of p-toluenesulfonic acid and sulfosalicylic acid with respect to the whole organic sulfonic acid were the values shown in Table 1. Oxidant solution 10, 11). When water content was measured in the same manner as in Production Example 1 for each oxidant solution, it was 1.0% by mass.

(Comparative Production Examples 3 to 5)
Instead of the sulfosalicylic acid used in Production Example 1, the organic sulfonic acid described in Table 1 was used, and the contents of p-toluenesulfonic acid and the organic sulfonic acid described in Table 2 with respect to the entire organic sulfonic acid were as shown in Table 2. Oxidant solutions were prepared in the same manner as in Production Example 1 except that the addition amounts were changed so as to obtain the indicated values (oxidant solutions 12 to 14). When water content was measured in the same manner as in Production Example 1 for each oxidant solution, it was 1.0% by mass.

(Comparative Production Examples 6 and 7)
Instead of sulfosalicylic acid used in Production Example 1, 4-methoxybenzenesulfonic acid (Comparative Production Example 6) and 4-hydroxybenzenesulfonic acid (Comparative Production Example 7) were used, and p-toluenesulfonic acid relative to the whole organic sulfonic acid. An oxidant solution was prepared in the same manner as in Production Example 1 except that the addition amount was changed so that the content of each of the organic sulfonic acids was the value shown in Table 2 (oxidant solutions 15 and 16). When water content was measured in the same manner as in Production Example 1 for each oxidant solution, it was 1.0% by mass.

Example 1
Production of solid electrolytic capacitors:
To the oxidant solution 1 prepared in Production Example 1, 3,4-ethylenedioxythiophene was added as a polymerizable monomer so as to have a mass ratio of 2.5: 1 (oxidant solution: polymerizable monomer), and the temperature was increased to 18 ° C. The polymerization solution was prepared by stirring on the set thermoplate. This polymerized solution was impregnated with a wound aluminum solid electrolytic capacitor element for 1 minute. Thereafter, a polymerization reaction is carried out at 45 ° C. for 1 hour, then at 100 ° C. for 10 minutes, and further dried at 150 ° C. for 10 minutes and at 200 ° C. for 10 minutes to form a conductive polymer layer on the wound capacitor, thereby producing a solid electrolytic capacitor Produced.

(Examples 2-9)
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the oxidant solution 1 was replaced with the oxidant solutions 2 to 9 prepared in Production Examples 2 to 9.

(Comparative Examples 1 and 2)
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the oxidant solution 1 was replaced with the oxidant solutions 10 and 11 prepared in Comparative Production Examples 1 and 2.

(Comparative Examples 3 to 7)
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the oxidant solution 1 was replaced with the oxidant solutions 12 to 16 prepared in Comparative Production Examples 3 to 7.

(Evaluation of solid electrolytic capacitors)
Using the solid electrolytic capacitors obtained in Examples 1 to 9 and Comparative Examples 1 to 7, a heat resistance test of a load voltage of 4.0 V for 500 hours was performed in a thermostat at 125 ° C., and an LCR meter (model name: 4284A, Agilent) The capacitance (μF, 120 Hz) and ESR (mΩ, 100 kHz) after the initial stage and after the heat resistance test were measured using a technology manufactured by Technology. Moreover, the change rate from the initial value was calculated about each. The results are shown in Table 3.

  From Table 3, it was found that all of the solid electrolytic capacitors of Examples 1 to 9 exhibited high capacitance, low ESR, and excellent heat resistance.

  Since the solid electrolytic capacitor manufactured using the oxidant solution for manufacturing a conductive polymer of the present invention has excellent electrical characteristics, it can be applied to various digital devices used in a high frequency region.

Claims (6)

An oxidizing agent solution for producing a conductive polymer containing a ferric organic sulfonic acid salt in a solvent, and as an organic sulfonic acid contained in the ferric organic sulfonic acid salt,
The alkylbenzene sulfonic acid represented by the following general formula (1) and the benzene sulfonic acid represented by the following general formula (2) are contained, and the alkylbenzene sulfonic acid represented by the general formula (1) with respect to the whole organic sulfonic acid is contained. The amount is 60 to 99 mol%, the content of benzenesulfonic acid represented by the general formula (2) is 1 to 40 mol%, and an alcohol solvent is the main solvent. Oxidant solution.

(In the formula (1), _{R 1} represents an alkyl group having 1 to 4 carbon atoms, _{R 2} is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a hydroxy group N is an integer of 1 or 2.)   The oxidant solution for producing a conductive polymer according to claim 1, wherein the benzenesulfonic acid represented by the general formula (2) is sulfosalicylic acid.   The oxidant solution for producing a conductive polymer according to claim 1 or 2, wherein the alcohol solvent is one or more selected from the group consisting of methanol, ethanol and butanol.   Water content is less than 5 mass%, The oxidizing agent solution for electroconductive polymer manufacture as described in any one of Claim 1 to 3 characterized by the above-mentioned.   It has the conductive polymer layer formed by carrying out the chemical oxidative polymerization reaction of the polymerizable monomer using the oxidizing agent solution for conductive polymer manufacture as described in any one of Claim 1 to 4. Solid electrolytic capacitor.   Chemical oxidative polymerization reaction of polymerizable monomer and oxidant by impregnating capacitor element with liquid mixture of polymerizable monomer and oxidant solution, or impregnating capacitor element with polymerizable monomer solution and oxidant solution In the manufacturing method of the solid electrolytic capacitor including the process of making it form a conductive polymer layer in a capacitor element, the oxidizing agent for conductive polymer manufacture according to any one of claims 1 to 4 as an oxidizing agent solution. A method for producing a solid electrolytic capacitor, comprising using a solution.