JP2011210918A - Electrolytic polymerization solution for forming conductive polymer, and method of manufacturing solid electrolytic capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic polymerization solution for forming a conductive polymer excellent in heat resistance, and to provide a method of manufacturing a solid electrolytic capacitor using the same, low in ESR (Equivalent Series Resistance), and high in heat resistance.SOLUTION: The electrolytic polymerization solution for forming the conductive polymer contains a supporting electrolyte containing a naphthalene sulfonic acid compound, and a supporting electrolyte containing a sulfonic acid compound ranging from 29 to 33 in HLB (Hydrophilic-Lipophilic Balance) value calculated by the Davis method. The solid electrolytic capacitor manufactured by using the solution and the method of manufacturing the solid electrolytic capacitor are provided.

Description

  The present invention relates to a method for producing a solid electrolytic capacitor in which a solid electrolyte layer made of a conductive polymer formed using an electropolymerization liquid for forming a conductive polymer is formed.

  A solid electrolytic capacitor in which a dielectric oxide film is formed on the surface of a valve metal such as aluminum or tantalum, and a conductive polymer having a high electrical conductivity is formed on the dielectric oxide film as a solid electrolyte has a capacitance. It is known that it has an excellent characteristic that it has a high equivalent series resistance (hereinafter abbreviated as “ESR”).

  In general, the solid electrolytic capacitor has a valve-acting metal foil whose surface area is enlarged by etching treatment, or a sintered body whose surface area is enlarged by sintering particles of valve-acting metal, and a dielectric material on the surface by chemical conversion treatment. An oxide film is formed, then a solid electrolyte layer is formed on the dielectric oxide film, a conductive layer made of carbon and silver paste is sequentially formed, and then connected to an external terminal such as a lead frame, by transfer molding or the like It is commercialized with an exterior.

  The ESR of a solid electrolytic capacitor is mainly composed of a combined resistance consisting of the specific resistance of each member forming the capacitor and the contact resistance generated between each member forming the capacitor. Further reduction is desired.

  Deterioration of solid electrolytic capacitors is generally due to thermal degradation of each member forming the capacitor and oxygen sources such as moisture entering through the exterior of the capacitor, in addition to accidents that occur accidentally. Oxidative degradation of these materials is a major factor, and against these degradation factors, improvement of the thermal durability performance of each member that forms the capacitor, especially the solid electrolyte layer, and improvement of gas barrier properties centering on exterior members, etc. Measures are being taken.

  Common solid electrolytes used for solid electrolytic capacitors include polypyrrole and polyethylene dioxythiophene. More specifically, polypyrrole mainly formed by electrolytic oxidation polymerization and polyethylene dioxy formed by chemical oxidation polymerization. Broadly divided into thiophenes.

  Since the solid electrolyte formed by electrolytic oxidation polymerization can form a dense film, it tends to have excellent conductivity, and is used in the manufacture of multilayer capacitors. On the other hand, chemical oxidative polymerization can be used even for devices having complicated shapes, and is therefore often used in the manufacture of winding type capacitors.

  Regarding the inherent performance of the solid electrolyte forming the solid electrolytic capacitor, not only the type of polymer such as polypyrrole or polyethylenedioxythiophene, but also the conductivity of the solid electrolyte, thermal durability, etc. depending on the dopant used when forming the solid electrolyte It is known that the performance of the system changes greatly.

  As disclosed in Patent Document 1 and Patent Document 2, in a solid electrolyte made of polypyrrole used for a multilayer solid electrolytic capacitor, paratoluenesulfonic acid and naphthalenesulfonic acid can be cited as typical supporting electrolytes. The solid electrolyte composed of polypyrrole using the above-mentioned paratoluenesulfonic acid and naphthalenesulfonic acid as a supporting electrolyte has insufficient conductivity and thermal durability, and the obtained solid electrolytic capacitor has high ESR and durability at high temperatures. There was a fault that the property was low.

  As disclosed in Patent Document 1 and Patent Document 2, in a solid electrolyte made of polypyrrole used for a multilayer solid electrolytic capacitor, paratoluenesulfonic acid and naphthalenesulfonic acid can be cited as typical supporting electrolytes. The solid electrolyte made of polypyrrole using the paratoluenesulfonic acid and naphthalenesulfonic acid as a supporting electrolyte has insufficient conductivity and thermal durability, and the obtained solid electrolytic capacitor has high ESR and low thermal durability. There was a drawback.

Japanese Patent Laid-Open No. 06-77093 JP 2001-110682 A

  An object of the present invention is to provide an electropolymerization liquid for forming a conductive polymer that gives a solid electrolyte layer excellent in heat durability, and has a low ESR and a high ESR using the electropolymerization liquid for forming a conductive polymer It is to provide a method for producing a solid electrolytic capacitor having thermal durability.

  As a result of intensive studies, the inventors of the present invention have a conductive electrolyte containing a supporting electrolyte containing a naphthalenesulfonic acid compound and a supporting electrolyte containing a sulfonic acid compound having an HLB value calculated by the Davis method in the range of 29 to 33. It has been found that an electrolytic polymerization solution for polymer formation, a solid electrolytic capacitor produced using the same, and a method for producing the same solve the above-mentioned problems, and have been completed.

  Hereinafter, the present invention will be described in detail.

The first invention is a conductive polymer forming electrolyte solution in which a conductive polymer monomer and a supporting electrolyte are dissolved in a solvent.
A supporting electrolyte (D1) containing a naphthalenesulfonic acid compound represented by the following general formula (1);
A supporting electrolyte (D2) containing a sulfonic acid compound having an HLB value calculated by the Davis method in the range of 29 to 33;
It is an electropolymerization liquid for conductive polymer formation characterized by containing.

（式（１）中、Ｒは同一でも異なっていてもよいハロゲン基又は炭素数１〜９の直鎖状又は分岐鎖状アルキル基を示す。Ｘ^＋はカチオンを示し、ｍは１〜４の整数であり、ｎは１〜３の整数である。）

(In formula (1), R represents the same or different halogen group or a linear or branched alkyl group having 1 to 9 carbon atoms. X ⁺ represents a cation, and m represents 1 to 4. An integer, and n is an integer of 1 to 3.)

  The second invention is the electropolymerization liquid for forming a conductive polymer according to the first invention, wherein the sulfonic acid compound is a benzenesulfonic acid compound represented by the following general formula (2).

（式（２）中、Ｒは同一でも異なっていてもよい炭素数１〜１５の直鎖状又は分岐鎖状アルキル基を示す。Ｘ^＋はカチオンを示し、ｍは１〜４の整数であり、ｎは１〜３の整数である。）

(In the formula (2), R represents a linear or branched alkyl group having 1 to 15 carbon atoms which may be the same or different. X ⁺ represents a cation, and m is an integer of 1 to 4. , N is an integer from 1 to 3.)

  3rd invention is a conductive polymer as described in 1st or 2nd invention characterized by the molar ratio of supporting electrolyte (D1) and supporting electrolyte (D2) being 9: 1-2: 8. This is an electrolytic polymerization solution for formation.

  According to a fourth aspect of the invention, there is provided the conductive material according to any one of the first to third aspects, wherein at least one compound represented by the following general formulas (3) to (5) is dissolved as an additive. It is an electropolymerization liquid for forming a conductive polymer.

（式（３）〜（５）中、Ｒはそれぞれ同一でも異なっていてもよい水素原子、炭素数１〜６の直鎖状又は分岐鎖状アルキル基又はフェニル基を示す。）

(In formulas (3) to (5), R represents a hydrogen atom which may be the same as or different from each other, a linear or branched alkyl group having 1 to 6 carbon atoms, or a phenyl group.)

  5th invention is an electropolymerization liquid for conductive polymer formation in any one of 1st to 4th invention, The said conductive polymer monomer is a pyrrole and / or a pyrrole derivative. It is.

According to a sixth aspect of the present invention, a conductive polymer layer is formed on the valve action metal on which the dielectric oxide film is formed in the electropolymerization liquid for forming a conductive polymer according to any one of the first to fifth aspects. A method for producing a solid electrolytic capacitor having at least a step of forming by electrolytic polymerization.
It is.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the solid electrolytic capacitor from which the solid electrolytic capacitor which shows the remarkably outstanding ESR characteristic and heat durability compared with the conventional solid electrolytic capacitor can be provided.

  First, the electrolytic solution for electrolytic polymerization of the present invention will be described.

In the electrolytic solution for forming a conductive polymer in which the conductive polymer monomer and the supporting electrolyte are dissolved in a solvent,
A supporting electrolyte (D1) containing a naphthalenesulfonic acid compound represented by the following general formula (1);
A supporting electrolyte (D2) containing a sulfonic acid compound having an HLB value calculated by the Davis method in the range of 29 to 33;
It is an electropolymerization liquid for conductive polymer formation characterized by containing.

  The electropolymerization liquid for forming a conductive polymer of the present invention is a solution in which a supporting electrolyte capable of releasing a dopant and a polymerizable monomer that is a conductive polymer monomer are dissolved in a solvent.

  As the polymerizable monomer, pyrrole, aniline, furan, thiophene, or derivatives thereof can be used. Examples of the derivative include 3-alkylpyrrole, 3-alkylthiophene, 3,4-alkylenedioxypyrrole, 3,4-alkylenedioxythiophene, and the like. The monomer may contain one kind or two or more kinds at the same time. Among these, pyrrole and / or a derivative thereof are preferable from the viewpoint of toughness, conductivity and durability of the obtained conductive polymer.

The solvent of the electrolytic polymerization electrolytic solution is water, ethers such as tetrahydrofuran (THF), dioxane, and diethyl ether, ketones such as acetone and methyl ethyl ketone, dimethylformamide (DMF), acetonitrile, benzonitrile, N-methylpyrrolidone ( NMP), aprotic polar solvents such as dimethyl sulfoxide (DMSO), esters such as ethyl acetate and butyl acetate, non-aromatic chlorine solvents such as chloroform and methylene chloride, nitro compounds such as nitromethane, nitroethane, and nitrobenzene Or a mixture of alcohols such as methanol, ethanol, and propanol, or organic acids such as formic acid, acetic acid, and propionic acid, or acid anhydrides (such as acetic anhydride) of the organic acids mixed with water at a ratio of 0 to 30% or less. Mention may be made of solvents.
Among these, from the viewpoint of environmental load and safety, those using water alone are preferable.

  The naphthalenesulfonic acid compound used for the supporting electrolyte (D1) can be represented by the following general formula (1).

In said general formula (1), R shows the halogen group which may be the same or different, or a C1-C9 linear or branched alkyl group. X ⁺ represents a cation, m is an integer of 1 to 4, and n is an integer of 1 to 3.

  Examples of the halogen group include fluorine, chlorine, bromine and the like.

  Examples of the linear or branched alkyl group having 1 to 9 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, an octyl group, an isopropyl group, and an isobutyl group.

  Specific examples of naphthalenesulfonic acid include, for example, naphthalenesulfonic acid, methylnaphthalenesulfonic acid, dimethylnaphthalenesulfonic acid, trimethylnaphthalenesulfonic acid, tetramethylnaphthalenesulfonic acid, propylnaphthalenesulfonic acid, dipropylnaphthalenesulfonic acid, butylnaphthalenesulfone. Acid, dibutyl naphthalene sulfonic acid, tributyl naphthalene sulfonic acid, naphthalene disulfonic acid, methyl naphthalene disulfonic acid, dimethyl naphthalene disulfonic acid, trimethyl naphthalene disulfonic acid, propyl naphthalene disulfonic acid, dipropyl naphthalene disulfonic acid, butyl naphthalene disulfonic acid, dibutyl naphthalene disulfonic acid Acid, tributyl naphthalene disulfonic acid, etc., and miscibility with polymerizable monomers Ri, butyl naphthalene sulfonic acid are preferably exemplified. You may use a naphthalenesulfonic acid compound individually or in mixture of 2 or more types.

X ⁺ in the general formula (1) represents a cation, and examples thereof include a hydrogen ion, an ammonium cation, and an alkali metal cation.
Examples of the ammonium cation include NH ₄ ⁺ , NH ₃ R ⁺ , NH ₂ R ₂ ⁺ , NHR ₃ ⁺ , NR ₄ ^{+ and the} like. R is an alkyl group having 1 to 6 carbon atoms.
Examples of the alkali metal cation include lithium ion, sodium ion, and potassium ion.
Of these cations, sodium ions are preferred.
These cations can be used alone or in combination of two or more.

Accordingly, specific examples of the compound represented by the general formula (1) include sodium butylnaphthalenesulfonate.
The compound represented by the general formula (1) can be used alone or in combination of two or more.

The supporting electrolyte (D2) is characterized by containing a sulfonic acid compound having an HLB value of 29 to 33 according to the Davis method. The HLB value is an abbreviation for Hydrophilic-Lipophilic-Balance and represents the balance between hydrophilicity and lipophilicity of a surfactant. A smaller value indicates stronger lipophilicity, and a larger value indicates stronger hydrophilicity. Although there are a plurality of ways of obtaining the HLB value, the Davis method is adopted in which the number of bases based on each structure of the atomic group constituting the surfactant is integrated. Radix, for example, -CH ₂ - if -0.475, which is 38.7 if _-SO 3 Na. It can be calculated by the following formula (1).

  [1] in the above formula (1) represents the number of hydrophilic groups, and [2] represents the number of hydrophobic groups.

By using a sulfonic acid compound having an HLB value in the range of 29 to 33, ESR can be lowered.
In the case of less than 29 or more than 33, there is a defect that excellent ESR cannot be obtained.

  Examples of the sulfonic acid compound having an HLB value of 29 to 33 include a benzenesulfonic acid compound and a naphthalenesulfonic acid compound, and a benzenesulfonic acid compound is preferable.

  The benzenesulfonic acid compound can be represented by the following general formula (2).

In said general formula (2), R shows the C1-C15 linear or branched alkyl group which may be the same or different. X ⁺ represents a cation, m is an integer of 1 to 4, and n is an integer of 1 to 3.

  Examples of the linear or branched alkyl group having 1 to 15 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, an octyl group, an isopropyl group, and an isobutyl group.

Benzenesulfonic acid compound represented by the general formula (2) is, HLB value when the total number of carbon atoms of _{R m} is 7-15 has features that fall within the scope of 29 to 33.

  Specific examples of the benzenesulfonic acid compound in the general formula (2) include octylbenzenesulfonic acid, nonylbenzenesulfonic acid, decylbenzenesulfonic acid, undecylbenzenesulfonic acid, dodecylbenzenesulfonic acid, tridecylbenzenesulfonic acid, Examples include tetradecylbenzene sulfonic acid.

X ⁺ in the general formula (1) represents a cation, and examples thereof include a hydrogen ion, an ammonium cation, and an alkali metal cation.
Examples of the ammonium cation include NH ₄ ⁺ , NH ₃ R ⁺ , NH ₂ R ₂ ⁺ , NHR ₃ ⁺ , NR ₄ ^{+ and the} like. R is an alkyl group having 1 to 6 carbon atoms.
Examples of the alkali metal cation include lithium ion, sodium ion, and potassium ion.
Of these cations, sodium ions are preferred.
These cations can be used alone or in combination of two or more.

Therefore, specific examples of the compound represented by the general formula (2) include, for example, sodium octylbenzenesulfonate, sodium nonylbenzenesulfonate, sodium decylbenzenesulfonate, sodium undecylbenzenesulfonate, dodecylbenzenesulfonate. Examples thereof include sodium, sodium tridecylbenzenesulfonate, sodium tetradecylbenzenesulfonate, and the like.
The compound represented by the general formula (2) may be used alone or in combination of two or more.

  The compound represented by the general formula (2) has a relatively low HLB value, so that it can be more efficiently incorporated into the electropolymerized film to give a highly conductive conductive polymer, and a conductive material having the dopant. The functional polymer is less likely to cause the desorption of the dopant, and further has excellent thermal durability.

  The molar ratio of the supporting electrolyte (D1) and the supporting electrolyte (D2) in the electropolymerization liquid for forming a conductive polymer is preferably D1: D2 = 2: 8-9: 1, more preferably 4: 6-8: 2. Can be mentioned. Outside the range of D1: D2 = 2: 8 to 9: 1, there is a drawback that excellent ESR and thermal durability cannot be obtained.

  The electrolyte solution of the present invention can contain an additive. The additive used in the present invention is preferably one having mainly the characteristics of either an antioxidant or a surfactant. More preferred as such additives are compounds represented by the following formulas (3) to (5).

  In the general formulas (3) to (5), R represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a phenyl group, which may be the same or different.

Specific examples of the compound represented by the general formula (3) include, for example, 4-nitrophenol, 2-methyl-4-nitrophenol, 3-methyl-4-nitrophenol, 2-ethyl-4-nitrophenol. , Nitrophenols such as 3-ethyl-4-nitrophenol, 2-hexyl-4-nitrophenol and 3-hexyl-4-nitrophenol.
Specific examples of the compound represented by the general formula (4) include nitronaphthols such as 4-nitro-1-naphthol.
Specific examples of the compound represented by the general formula (5) include nitroanthraquinones such as 1-hydroxy-4-nitroanthraquinone.

  The compound represented by the general formulas (3) to (5) can be used alone or in combination of two or more. The compounds represented by the above general formulas (3) to (5) are 4-nitrophenol, 4-nitro-1-naphthol, 1-hydroxy-4-phenyl from the viewpoint of thermal durability of the obtained conductive polymer. Nitroanthraquinone is preferred.

  Furthermore, by conducting the electropolymerization using an electropolymerization liquid for forming a conductive polymer containing a supporting electrolyte salt and an additive, a conductive polymer that is remarkably excellent in thermal durability can be obtained.

A method for producing a solid electrolytic capacitor using the electropolymerization liquid for forming a conductive polymer of the present invention will be described. A conductive polymer layer is preliminarily formed as a precoat layer on the dielectric oxide film on the surface of the valve metal, and then a new conductive polymer layer is formed on the precoat layer using the electrolytic polymerization solution of the present invention. After forming a solid electrolyte layer by forming by electropolymerization, a cathode layer is formed by applying and drying a conductive paste such as carbon paste and silver paste on the solid electrolyte layer.
As a method for forming the conductive polymer of the precoat layer, (1) a method of forming a conductive polymer layer by chemical polymerization, (2) a method of forming a conductive polymer layer by applying and drying a conductive polymer solution Is mentioned.
Next, the anode lead terminal is connected from the valve action metal, the cathode lead terminal is connected from the cathode layer, and the electrode is taken out to form an element. A solid electrolytic capacitor can be obtained by sealing with, for example.

  By using the electropolymerization liquid for forming the conductive polymer, a conductive polymer having excellent conductivity and taking a specific stable structure when exposed to high temperature is obtained. By using a solid electrolyte, it is possible to obtain a solid electrolytic capacitor having ESR characteristics and thermal durability that are remarkably superior to conventional ones.

  The anode valve action metal used in the present invention includes one selected from the group consisting of aluminum, tantalum, niobium and titanium, and is used in the form of a sintered body or foil.

  In the manufacturing method of the solid electrolytic capacitor of this invention, it can be set as either a chip type or a winding type according to the kind and shape of the anode valve action metal used.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited at all by the following manufacturing methods.

<Evaluation of solid electrolytic capacitors>
Example 1
A 3 mm × 5 mm size etched aluminum foil with a dielectric oxide film formed on the surface was formed at 10 V in a 150 g / l ammonium adipate aqueous solution at 85 ° C., washed with pure water, and 10 ° C. in a 105 ° C. dryer. Let dry for minutes. This was left to stand on an 18 ° C. thermoplate for 10 minutes. Next, 4 μl of a monomer liquid (pyrrole: 3 (g) + ethanol: 5 (g) + H ₂ O: 18.4 (g) mixed liquid) cooled to 18 ° C. was dropped on the foil and left for 1 minute. did. Furthermore, an oxidizing agent solution (p-toluenesulfonate tetraethylammonium (PTS-TEA): 5.6 (mmol) + ammonium peroxodisulfate: 1.56 (g) + H ₂ O: 10.63 (g)) : 12 μl was dropped on the foil and left to stand for 10 minutes for chemical oxidative polymerization to form a precoat layer. This was washed with pure water and dried in a 105 ° C. dryer for 10 minutes.

Next, electrolytic polymerization solution (sodium butylnaphthalenesulfonate (Tokyo Chemical Industry Co., Ltd.): 1.96 (mmol) + sodium octylbenzenesulfonate (Tokyo Chemical Industry Co., Ltd., special grade): 0.84 (mmol) + Pyrrole: 0.6 (g) + H ₂ O: 45.8 (g)).

  A conductive polymer layer is formed by immersing an etched aluminum formed foil with a precoat layer formed in an electrolytic polymerization solution, using the external electrode brought into contact with the precoat layer as an anode, fixing the current value to 0.4 mA, and performing electrolytic polymerization. (Solid electrolyte layer) was formed.

  Next, a carbon paste and a silver paste were sequentially applied to the portion of the aluminum foil where the conductive polymer layer was formed and dried to complete a total of 20 capacitor elements.

  For these 20 capacitor elements, the equivalent series resistance (ESR) at 100 Hz and the equivalent series resistance (ESR) at 100 Hz after heat treatment at 150 ° C. for 8 hours were measured as initial characteristics.

(Example 2)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. In other words, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 0.28 (mmol) + sodium sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 2.52 ( mmol) + pyrrole: 0.6 (g) + H ₂ O: 45.8 (g) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Example 3)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 0.56 (mmol) + sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 2.24 ( mmol) + pyrrole: 0.6 (g) + H ₂ O: 45.8 (g) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

Example 4
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. Namely, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 1.12 (mmol) + sodium sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 1.68 ( mmol) + pyrrole: 0.6 (g) + H ₂ O: 45.8 (g) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Example 5)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 1.68 (mmol) + sodium sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 1.12 ( mmol) + pyrrole: 0.6 (g) + H ₂ O: 45.8 (g) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Example 6)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 1.96 (mmol) + sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 0.84 ( mmol) + pyrrole: 0.6 (g) + H ₂ O: 45.8 (g) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Example 7)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 2.24 (mmol) + sodium sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 0.56 ( mmol) + pyrrole: 0.6 (g) + H ₂ O: 45.8 (g) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.
(Example 8)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, butyl naphthalenesulfonate sodium (Tokyo Chemical Industry Co., Ltd.): 2.52 (mmol) + sodium dodecylbenzenesulfonate (soft type, mixture, Tokyo Chemical Industry Co., Ltd.): 0.28 (electrolytic polymerization solution) mmol) + pyrrole: 0.6 (g) + H ₂ O: 45.8 (g) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.
Example 9
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 1.96 (mmol) + sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 0.84 ( mmol) + pyrrole: 0.6 (g) + 4-nitrophenol: 0.229 (mmol) + H ₂ O: 45.8 (g) is used for electrolytic polymerization to form a conductive polymer layer. did. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Example 10)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 1.96 (mmol) + sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 0.84 ( mmol) + pyrrole: 0.6 (g) + 4-nitro-1-naphthol: 0.229 (mmol) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Example 11)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 1.96 (mmol) + sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 0.84 ( mmol) + pyrrole: 0.6 (g) + 1-hydroxy-4-nitroanthraquinone: 0.229 (mmol) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Comparative Example 1)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, a mixed solution of sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 2.8 (mmol) + pyrrole: 0.6 (g) + H ₂ O: 45.8 (g) was used for the electrolytic polymerization solution. Then, electropolymerization was performed to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Comparative Example 2)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium dodecylbenzenesulfonate (soft type, mixture, manufactured by Tokyo Chemical Industry Co., Ltd.): 2.8 (mmol) + pyrrole: 0.6 (g) + H ₂ O: 45.8 (g) An electropolymerization was performed using the mixed solution to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Comparative Example 3)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 1.96 (mmol) + sodium p-toluenesulfonate (manufactured by Wako Pure Chemical Industries, Ltd.): 0.84 (mmol) + pyrrole : 0.6 (g) + H ₂ O: 45.8 (g) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

(Comparative Example 4)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium butylnaphthalenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 1.96 (mmol) + sodium hexadecylbenzenesulfonate: 0.84 (mmol) + pyrrole: 0.6 (g) + H Electrolytic polymerization was performed using a mixed solution of ₂ O: 45.8 (g) to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.
Sodium hexadecylbenzenesulfonate was synthesized by the following method. That is, hexadecylbenzene (manufactured by Wako Pure Chemical Industries) 20 (g) and 20% fuming sulfuric acid 24 (g) were reacted at 25 ° C. for 10 hours, water 12 (g) was added, and the mixture was allowed to stand at 38 ° C. for 20 hours. Then, the sodium hexadecylbenzenesulfonate was obtained by neutralizing with 20 mass% sodium hydroxide aqueous solution.

(Comparative Example 5)
Twenty capacitor elements were obtained in the same manner as in Example 1 except that the method for producing the conductive polymer was changed to the following method. That is, sodium dodecylbenzenesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.): 1.00 (mmol) + sodium p-toluenesulfonate (manufactured by Wako Pure Chemical Industries, Ltd.): 1.00 (mmol) + pyrrole : 0.6 (g) + H ₂ O: 45.8 (g) was used for electrolytic polymerization to form a conductive polymer layer. The characteristics of the capacitor element were evaluated in the same manner as in Example 1.

  Table 1 shows the measurement results of the capacitor elements of Examples 1 to 11 and Comparative Examples 1 to 5.

Abbreviations in the table are shown below.
BNS-Na: sodium butylnaphthalenesulfonate OBS-Na: sodium octylbenzenesulfonate DBS-Na: sodium dodecylbenzenesulfonate PTS-Na: sodium paratoluenesulfonate HBS-Na: sodium hexadecylbenzenesulfonate NP: 4- Nitrophenol NNP: 4-nitro-1-naphthol-4-nitrophenol HNA: 1-hydroxy-4-nitroanthraquinone

  When Examples 1 to 11 and Comparative Examples 1 to 5 were compared, Examples 1 to 11 showed a reduction in ESR of the capacitor and an improvement in thermal durability. In particular, in Examples 9 to 11 to which additives were added, it was found that the thermal durability was significantly improved.

  The conductive polymer obtained by the electropolymerization liquid for forming a conductive polymer of the present invention is not only a solid electrolytic capacitor, but also an organic EL display, an organic transistor, a polymer battery, a solar battery, various sensor materials, an electromagnetic shielding material, an antistatic material. It can be suitably used for materials, electrochromic materials, artificial muscles and the like.

Claims (7)

In the electrolytic solution for forming a conductive polymer in which the conductive polymer monomer and the supporting electrolyte are dissolved in a solvent,
A supporting electrolyte (D1) containing a naphthalenesulfonic acid compound represented by the following general formula (1);
A supporting electrolyte (D2) containing a sulfonic acid compound having an HLB value calculated by the Davis method in the range of 29 to 33;
An electropolymerization liquid for forming a conductive polymer, comprising:

(In formula (1), R represents the same or different halogen group or a linear or branched alkyl group having 1 to 9 carbon atoms. X ⁺ represents a cation, and m represents 1 to 4. An integer, and n is an integer of 1 to 3.) The electropolymerization liquid for forming a conductive polymer according to claim 1, wherein the sulfonic acid compound is a benzenesulfonic acid compound represented by the following general formula (2).

(In the formula (2), R represents a linear or branched alkyl group having 1 to 15 carbon atoms which may be the same or different. X ⁺ represents a cation, and m is an integer of 1 to 4. , N is an integer from 1 to 3.)   The electropolymerization liquid for forming a conductive polymer according to claim 1 or 2, wherein the molar ratio of the supporting electrolyte (D1) and the supporting electrolyte (D2) is 9: 1 to 2: 8. The electropolymerization liquid for forming a conductive polymer according to any one of claims 1 to 3, wherein at least one compound represented by the following general formulas (3) to (5) is dissolved as an additive. .

(In formulas (3) to (5), R represents a hydrogen atom which may be the same as or different from each other, a linear or branched alkyl group having 1 to 6 carbon atoms, or a phenyl group.)   5. The electropolymerization liquid for forming a conductive polymer according to any one of claims 1 to 4, wherein the conductive polymer monomer is pyrrole and / or a pyrrole derivative.   A step of forming a conductive polymer layer by electropolymerization in the electropolymerization liquid for forming a conductive polymer according to any one of claims 1 to 5 on the valve action metal on which the dielectric oxide film is formed. A method for producing a solid electrolytic capacitor.   The step of forming a conductive polymer layer (A) on the valve action metal on which the dielectric oxide film is formed, and the conductive polymer layer (A) according to any one of claims 1 to 5 And a step of forming a conductive polymer layer (B) by electrolytic polymerization in an electrolytic polymerization solution.