JP2001163960A - Method for preparing electrically conductive polymer material and solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a film of an electrically conductive polymer material, which is uniform and thick in thickness and has a large area. SOLUTION: A monomer, for example, pyrrol, thiophene or aniline, that can give a π-electron conjugated polymer compound in the presence of a compound having reversibly oxidizing and reducing properties, is electrochemically oxidized and polymerized to produce a filmy matter of an electrically conductive polymer material. The compound having reversibly oxidizing and reducing properties may preferably include hydroquinone, a hydroquinone derivative such as 4-methoxyphenol, a transition metal salt of an aromatic sulfonic acid, or the like. The resultant electrically conductive polymer material is suitably used as a solid electrolyte material for a solid electrolytical capacitor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a conductive polymer material containing a π-electron conjugated polymer compound, and a solid electrolytic capacitor using the same.

[0002]

BACKGROUND OF THE INVENTION In recent years, with the development of electronics technology, new materials for use therein have been developed. In particular, technological innovations in the field of functional organic materials have been remarkably progressing. Conductive polymer materials doped with compounds as dopants have been developed. Among them, for example, there are examples which have already been put to practical use as capacitor electrode materials, battery electrode materials, antistatic materials and the like.

[0003] However, many conductive polymer materials do not melt or dissolve, so that the molding method is extremely limited. For example, as a method of manufacturing a film of a conductive polymer material, a method of electrochemically oxidizing and polymerizing a monomer such as pyrrole or thiophene to form a film directly on an electrode plate is known. The polypyrrole film produced by that method has high mechanical strength, so it can be easily peeled off from the electrode plate used for production, and has good electrical properties and stability in air. For this reason, thin and small-area films obtained exclusively by this method have been used for various purposes.

[0004] However, when this method is used to produce a large-area film or a thick film,
As the polymerization progresses, a lump or dendritic polymer is generated, and furthermore, the growth in the thickness direction of the film is suppressed, so that it is practically impossible to form a film having a uniform thickness and a large area. It was difficult.

In the method of chemically oxidative polymerization using an oxidizing agent such as hydrogen peroxide, potassium persulfate and iron chloride,
Usually, only a powdery polymer is obtained. Although a method of performing chemical oxidative polymerization at the interface between a solid phase and a liquid phase has been reported, it is said that a polymer obtained by the method has low electric conductivity.

Meanwhile, a solid electrolytic capacitor has attracted attention as a device capable of incorporating an electrochemical process using a small-area conductive polymer film, and a new field of conductive polymer capacitors is being developed. When the solid electrolyte layer in this conductive polymer capacitor is formed by an electrochemical oxidation polymerization method, it is necessary to disperse appropriate conductive particles on the dielectric layer.

[0007] Dispersing such conductive particles causes electrochemical oxidative polymerization under conditions where current is locally concentrated, and it is difficult for the formed polymer to sufficiently cover the dielectric layer. Seems difficult. As a result, it is expected that the capacity of the obtained capacitor will be insufficient, or that the capacity will change over time, causing a problem.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for producing a conductive polymer material by electrochemical oxidation polymerization, which suppresses the formation of a lump or tree-like polymer and has a uniform film thickness. It is intended to provide a method for producing a thick or large area polymer film. In particular, an object of the present invention is to provide a method capable of easily producing a film of a conductive polymer substance on an electrode where current concentration is likely to occur. Another object of the present invention is to provide a conductive polymer material suitable as a solid electrolyte material for a solid electrolytic capacitor.

[0009]

That is, the present invention provides a method for electrochemically oxidizing and polymerizing a monomer capable of forming a π-electron conjugated polymer compound in the presence of a compound having reversible oxidation and reduction properties. The present invention relates to a method for producing a conductive polymer material.

The reversibly oxidizing and reducing compound is preferably hydroquinone, a hydroquinone derivative compound such as 4-methoxyphenol, or a transition metal salt of aromatic sulfonic acid.

Here, the monomer which forms the π-electron conjugated polymer compound is preferably a compound which can be at least one kind of a repeating unit represented by the following general formula (1), (2) or (3). , Pyrrole, thiophene, aniline and derivatives thereof are preferred.

[0012]

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[0013]

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[0014]

Embedded image Here, in the above formula, R ^{1 to} R ⁸ are a hydrogen atom, an alkyl group, or an alkoxy group, and R ^{1 to} R ⁸ may be the same or different from each other, and * represents a repeating unit. Indicates the bonding position of

The anode used in this manufacturing method may be a mesh electrode in addition to the flat electrode, and may further include a conductor layer, a dielectric layer covering the conductor layer, and a dielectric layer. It may be a structure to which conductive particles are attached.

Further, the present invention relates to a solid electrolytic capacitor containing the conductive polymer obtained by the above-mentioned manufacturing method as a solid electrolyte material.

[0017]

DETAILED DESCRIPTION OF THE INVENTION A method for producing a conductive polymer substance A method for producing a conductive polymer substance according to the present invention and the use of the obtained conductive polymer substance for a capacitor will now be specifically described. .

The method for producing a conductive high molecular substance according to the present invention comprises the steps of:
This is a method of electrochemically oxidatively polymerizing a monomer capable of forming an electron conjugated polymer compound.

The monomer capable of forming a π-electron conjugated polymer compound is a monomer which is a repeating unit constituting the π-electron conjugated polymer compound and is particularly a compound which is polymerized by an electrochemical oxidation method. There is no restriction. Among them, the following general formula (1), which shows a good electric conductivity and produces a polymer substance having excellent mechanical strength,
Compounds forming the repeating unit represented by (2) or (3), that is, pyrrole and its derivatives, thiophene and its derivatives, and aniline and its derivatives are preferred.

[0020]

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Here, in the above formula, R ^{1 to} R ⁸ are a hydrogen atom, an alkyl group or an alkoxy group, and in the case of an alkyl group or an alkoxy group, a group having 1 to 12 carbon atoms is preferable. R ^{1 to} R ⁸ may be the same or different. * Indicates the bonding position of the repeating unit.

Specific examples of these monomers include pyrrole, thiophene, aniline, bipyrrole, bithiophene, 4-aminodiphenylamine, 3-methylthiophene, 3-methoxythiophene, terthiophene, 2,5
-Bipyroylthiophene, 2,5-bithienylpyrrole, trans-bithienylethylene, trans-bithienyl-
1,4-butadiene, 3,4-ethylenedioxythiophene, 3-octylthiophene, p, p′-bipyrroylbenzene, 2,5-biphenylterpyrrole, 2,5-
Bithienyl bipyrrole and terpyrrole can be mentioned. Among these, pyrrole and 3,4-ethylenedioxythiophene are particularly preferred.

In the present invention, the electrochemical oxidative polymerization reaction of the monomer proceeds in the presence of a compound having reversible oxidation and reduction properties. Here, the compound having a reversibly oxidizing and reducing property is not particularly limited as long as it can be oxidized in a potential range in which the monomer is polymerized by an electrochemical oxidation method, and in particular, hydroquinone or a derivative thereof, or Transition metal compounds can be preferably used.

As hydroquinone or a derivative thereof, a compound represented by the following general formula (4) is preferable.

Embedded image Here, R ⁹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ^{10 to} R ¹³ represent a hydrogen atom or 1 to 4 carbon atoms.
Wherein R ^{10 to} R ¹³ may be the same or different from each other.

Among the compounds represented by the formula (4), hydroquinone or 4-methoxyphenol is particularly preferred.

The transition metal compound which can be used as a compound having reversible oxidation and reduction properties is a compound of a metal element having two or more different stable oxidation states. Examples of the metal element include metals belonging to Group VIII of the periodic table, and in particular, nickel, ruthenium,
Cobalt and iron are desirable.

Examples of anions to be combined with cations composed of the transition metal element include halogen ions, sulfate ions, phosphorus hexafluoride ions, boron tetrafluoride ions, perchlorate ions, aromatic sulfonate ions, and fatty acids. Group sulfonic acid ion, trifluoromethane sulfonic acid ion, chlorosulfate ion and the like. Among these ions, aromatic sulfonate ions are preferred anions because they also act as dopants that impart high electrical conductivity to π-electron conjugated polymer compounds, particularly polypyrrole.

Specific examples of the aromatic sulfonic acid anion include benzenesulfonate ion, p-toluenesulfonic acid ion, 5-sulfosalicylic acid ion, α-naphthalenesulfonic acid ion, β-naphthalenesulfonic acid ion, dodecylbenzene Sulfonate ion, m-sulfobenzoate ion, p-hydroxybenzenesulfonate ion, m-sulfobenzamide ion, N-methyl-m
-Sulfobenzamide ion, N, N-dimethyl-m-
Sulfobenzamide ion, m-sulfobenzanilide ion, N, N-diphenyl-m-sulfobenzamide ion, m-sulfosalicylamide ion, m-sulfobenzoylurea ion, 1,3-benzenedisulfonate ion, 1,5- And naphthalenedisulfonic acid ions.

The amount of the reversibly oxidizing and reducing compound used during the oxidative polymerization is not particularly limited as long as the progress of the electrochemical oxidative polymerization, which is the main reaction, is not hindered. Although not intended, the amount is usually preferably 1 mol or less per 100 mol of monomers constituting the π-electron conjugated polymer compound.

The anode used for carrying out the electrochemical oxidative polymerization provides a current or potential necessary for the oxidative polymerization to proceed, and the physical potential is determined by the potential applied to the polymerization system during the oxidative polymerization reaction. Any shape and structure may be used as long as the electrode is formed from a material that does not cause a chemical change. In the present invention, in addition to a general plate-shaped anode, it is possible to use an anode having a shape in which current concentration is likely to occur.Also, even if an anode having such a shape is used, it has a high mechanical strength or has a large mechanical strength. An area of polymer film or polymer block can be manufactured.

Examples of the electrode shape in which current concentration is likely to occur include a mesh-like electrode, a plate-like electrode having irregularities, and a cylindrical electrode. Further, as another example of the anode structure in which current concentration is likely to occur, an anode having a structure in which a conductive material layer is covered with a dielectric material layer and conductive particles are further adhered on the dielectric material layer may be used. .

As a specific example of the latter, at least one side of the metal foil or plate forming the anode is oxidized to form an oxide coating layer (dielectric layer), or at least one of the metal foil or plate forming the anode is formed. There is a structure in which a layer made of a metal oxide is laminated on one side, and conductive particles are attached thereon. As a metal oxide constituting the dielectric layer, aluminum oxide, tantalum oxide, titanium oxide, or magnesium oxide is preferable. As another example,
A structure in which an insulating polymer material plate or film is closely attached to a conductive material plate or film to form a dielectric layer, and then conductive particles are deposited on the dielectric layer. Good.

Aluminum, tantalum, titanium, and magnesium are used as the metal foil constituting the conductive material layer of the anode, and platinum, stainless steel, carbon material, IT
O and the like can be exemplified. Insulating materials are generally used as the dielectric material, such as polyethylene terephthalate resin, polyethylene resin, polypropylene resin, polyvinylidene fluoride resin, polyimide resin, nylon resin, polyvinylidene chloride resin, polystyrene resin,
Bakelite resin, phenol resin and the like can be exemplified.

Further, as the conductive particles to be attached, particles of a metal oxide or an organic conductive material can be used. Examples of the metal oxide include oxides of at least one metal selected from the group consisting of manganese, tin, indium, and titanium, specifically, manganese dioxide, ITO, tin oxide, and titanium dioxide. Examples of the organic conductive material include the above-mentioned π-electron conjugated high molecular compound such as polypyrrole, polythiophene, and polyalinine, and materials such as tetracyanoquinodimethane complex and carbon. Here, as a method for attaching the conductive particles, methods such as firing, use of a chemical reaction on the surface of the metal oxide layer, and precipitation from a solution can be used.

A particularly preferred anode is a conductor layer made of metallic aluminum, an aluminum oxide layer covering the same, and a structure in which manganese dioxide particles or polypyrrole particles are adhered to the aluminum oxide layer.

A dopant agent is usually added to impart electrical conductivity to the π-electron conjugated polymer compound obtained by the electrochemical oxidation polymerization method, and also to serve as a supporting electrolyte in the electrochemical reaction. You. As the dopant agent,
Strongly acidic compounds or salts thereof are preferred, and aromatic sulfonic acids or aromatic sulfonic acid salts are particularly preferred.

Specifically, p-toluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, m-
Sulfobenzamide, m-sulfonebenzoic acid, p-hydroxybenzenesulfonic acid, 5-sulfosalicylic acid,
1,3-benzenedisulfonic acid, α-naphthalenesulfonic acid, β-naphthalenesulfonic acid, 1,5-naphthalenedisulfonic acid, N-methyl-m-sulfobenzamide,
N, N-dimethyl-m-sulfobenzamide, m-sulfobenzanilide, N, N-diphenyl-m-sulfobenzamide, m-sulfobenzoylurea, m-sulfosalicylamide and alkali metal salts thereof can be exemplified. .

The amount of the dopant agent used is 100
It is preferably used in the range of 1 to 10000 mol, and more preferably in the range of 10 to 1000 mol based on mol.

As the solvent used in the oxidative polymerization reaction,
Any substance can be used as long as it can dissolve all of the monomer, the dopant agent, the reversibly oxidizing and reducing compounds, and does not cause a chemical change even when an electric potential is applied. , Acetonitrile, propylene carbonate, dimethylformamide and the like can be used.

The reaction is carried out in a temperature range of -100 ° C to 150 ° C, preferably 0 to 50 ° C.
The application method may be any of a constant current method and a constant potential method. Further, the polymerization is preferably performed under an inert gas such as nitrogen or argon.

The conductive polymer obtained by this production method can be suitably used as a battery electrode material, a solid electrolyte material for a capacitor, an electromagnetic wave shielding material, an antistatic material and the like.

[0042] The co emissions Devon then conductive polymer material obtained by the present invention, will be described utilizing as a solid electrolyte material of the solid electrolytic capacitor. In general, the basic structure of a solid electrolytic capacitor is such that an anode and a solid electrolyte material layer are joined via a dielectric layer,
Electrode leads are attached to the anode and the solid electrolyte material layer, respectively.

Examples of the metal material constituting the anode include aluminum and tantalum, which are used as the anode in the form of a foil or a sintered body, and the surface of which may be etched. On the other hand, the solid electrolyte material layer is generally used by processing an inorganic or organic conductive material into a film shape, and is a film-like material manufactured by the above-described method for manufacturing a conductive polymer substance according to the present invention. Can be used. Further, a cathode formed of a metal may be provided on the surface. Further, between the solid electrolyte material layer and the metal cathode, a structure in which a graphite layer is provided to improve the contact between the two layers may be employed. The dielectric layer is generally an oxide layer of the anode metal, and can be formed by oxidizing the surface of the anode metal or painting a coating solution containing the oxide of the anode metal.

In order to join a conductive polymer substance to the dielectric layer as a solid electrolyte material, conductive particles are attached to the dielectric layer. Examples of the conductive particles include manganese dioxide and polypyrrole.

The solid electrolytic capacitor according to the present invention contains a conductive polymer substance obtained by the above-described manufacturing method as a solid electrolyte material, and a commonly used material can be directly applied to the anode. The shape of the solid electrolytic capacitor on which the solid electrolyte and the anode are arranged may be any shape such as a cylindrical shape and a dip shape.

[0046]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 m-Sulfobenzamide
02 g (20 mmol), pyrrole 1.34 g (20 m
mol) and hydroquinone 22 mg (200 μmo
l) was dissolved in 200 ml of pure water to prepare an electrochemical oxidation polymerization reaction solution. After nitrogen gas was bubbled through this reaction solution for 30 minutes to replace with nitrogen, a 4 cm square stainless steel mesh (mesh size 150) was used as an anode, and the other 4 cm.
1cm square stainless steel plate as cathode
Was immersed in the reaction solution at an interval of.

Using the immersed electrode, a current was passed at a constant potential of 1.5 V for 40 minutes to carry out oxidative polymerization. As a result, the gaps in the mesh of the anode were filled with a black polypyrrole film formed by polymerization. When the anode mesh with the formed black film was adhered on the printed material, the printed portion was completely covered and concealed, and the printed portion could not be seen through the film. Therefore, it was found that a polypyrrole film was obtained by performing pyrrole oxidative polymerization under the above polymerization conditions using a mesh electrode.

Example 2 p-Toluenesulfonic acid was used in place of m-sulfobenzamide used in Example 1.
The same operation as in Example 1 was performed except that 80 g was used,
A polypyrrole film could be formed on the mesh electrode.

Example 3 The same operation as in Example 1 was performed except that a stainless steel electrode of 4 cm square was used instead of the stainless mesh anode used in Example 1. The resulting polypyrrole film had a thickness of 132 μm, an electric conductivity (measured by a four-probe method) of 5 S / cm, and did not produce a massive or dendritic polymer.

Example 4 The same operation as in Example 2 was performed except that a stainless steel electrode of 4 cm square was used instead of the stainless mesh anode used in Example 2. A polypyrrole film was formed in the shape of an anode plate, and no bulky or dendritic polymer was formed.

Comparative Example 1 The same operation as in Example 1 was repeated without adding hydroquinone.
After this operation, the anode mesh was placed on the printed matter and the production status of the film was observed.As a result, the printed portion under the mesh could be clearly seen through, and from this, the mesh of the anode mesh remained as a gap. Are left as voids,
It was found that no film-like polypyrrole was formed. Note that polypyrrole was attached to the mesh itself.

Comparative Example 2 The same operation as in Example 2 was repeated except that no hydroquinone was added.
In the mesh of the anode, gaps were left as voids, and polypyrrole in the form of a film could not be obtained.

Comparative Example 3 The same operation as in Example 1 was repeated, except that no hydroquinone was added and a 4 cm square stainless steel plate electrode was used as the anode. A large number of massive or dendritic polypyrrole polymers are attached to the film-like material formed on the anode,
The thickness of the film part is 24 μm and the electrical conductivity is 156S
/ Cm.

[0055]

In the method for producing a conductive polymer substance according to the present invention, a compound having reversible oxidation and reduction properties is allowed to coexist in an oxidative polymerization system, which is difficult with the conventional electrochemical oxidative polymerization method. It is possible to produce a large π-electron conjugated polymer compound film having a large area or a large film thickness. At this time, a polymer film having a substantially uniform film thickness can be produced even if an electrode which tends to cause current concentration is used. Further, the conductive polymer substance obtained by this manufacturing method can be suitably used as a solid electrolyte material for a capacitor.

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Claims (20)

[Claims] 1. A conductive high molecular substance characterized in that a monomer capable of forming a π-electron conjugated high molecular compound is electrochemically oxidatively polymerized in the presence of a reversibly oxidizing and reducing compound. Production method. 2. The method according to claim 1, wherein the reversibly oxidizing and reducing compound is hydroquinone or a derivative thereof. 3. The method of claim 1, wherein the hydroquinone derivative compound is
3. Methoxyphenol.
3. The method for producing a conductive polymer material according to item 1. 4. The method according to claim 1, wherein the compound having reversible oxidation and reduction properties is a transition metal compound. 5. The method according to claim 1, wherein the transition metal compound is selected from the group consisting of VII of the periodic table.
The method for producing a conductive polymer material according to claim 4, wherein the compound is a compound of a metal belonging to Group I. 6. The method according to claim 4, wherein the transition metal compound is a metal salt of an aromatic sulfonic acid. 7. The π-electron conjugated polymer compound according to claim 1, wherein said π-electron conjugated polymer compound is represented by the general formula (1), (2) or (3):
The method for producing a conductive polymer substance according to any one of claims 1 to 6, wherein the polymer compound has a kind of repeating unit. Embedded image Embedded image Embedded image (Wherein, R ^{1 to} R ⁸ are a hydrogen atom, an alkyl group, or an alkoxy group; R ^{1 to} R ⁸ may be the same or different; Indicates the bonding position of the unit.) 8. The method according to claim 1, wherein the π-electron conjugated high molecular compound is polypyrrole. 9. The method according to claim 1, wherein the oxidative polymerization is performed using a mesh anode electrode. 10. The oxidative polymerization is performed using an anode electrode composed of a conductor layer and a dielectric layer covering the conductor layer, and the dielectric layer further has conductive particles attached thereto. The method for producing a conductive polymer material according to any one of claims 1 to 8, wherein: 11. The method according to claim 10, wherein said dielectric layer is formed of a metal oxide. 12. The conductive material according to claim 11, wherein said metal oxide is any compound selected from the group consisting of aluminum oxide, tantalum oxide, titanium oxide, and magnesium oxide. A method for producing a polymer substance. 13. The method according to claim 10, wherein said dielectric layer is formed of an organic polymer compound. 14. The method according to claim 10, wherein said conductive particles are formed of a metal oxide. 15. The conductive material according to claim 14, wherein the metal oxide is an oxide of at least one metal selected from the group consisting of manganese, tin, indium, and titanium. A method for producing a polymer substance. 16. The method according to claim 10, wherein said conductive particles are formed of an organic conductive material. 17. The method according to claim 17, wherein the organic conductive material comprises at least one of the general formulas (1), (2) and (3).
17. The method for producing a conductive polymer material according to claim 16, comprising a π-electron conjugated polymer compound having a kind of repeating unit. Embedded image Embedded image Embedded image (Wherein, R ^{1 to} R ⁸ are a hydrogen atom, an alkyl group, or an alkoxy group; R ^{1 to} R ⁸ may be the same or different; Indicates the bonding position of the unit.) 18. The method according to claim 16, wherein the conductive particles are formed of polypyrrole, polythiophene, or polyaniline. 19. A method for producing a conductive layer made of metallic aluminum, an aluminum oxide layer covering the conductive layer, and an anode having manganese dioxide particles or polypyrrole particles adhered to the aluminum oxide layer, wherein hydroquinone or 4
-A method for producing polypyrrole, which comprises electrochemically oxidizing and polymerizing pyrrole in the presence of at least one methoxyphenol. 20. A conductive polymer obtained by electrochemically oxidizing and polymerizing a monomer capable of forming a π-electron conjugated polymer in the presence of a compound having reversible oxidation and reduction properties, and a solid electrolyte. A solid electrolytic capacitor characterized by being included as a material.