JP2010132873A - Method for producing dispersion liquid of electroconductive polymer, dispersion liquid of electroconductive polymer, electroconductive polymer and application thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a dispersion liquid of an electroconductive polymer from which an electroconductive polymer having high conductivity and excellent heat resistance is obtained, to provide an antistatic film having high conductivity and excellent heat resistance using the electroconductive polymer as a conductor, and also to provide a solid electrolytic capacitor having low ESR (Equivalent Series Resistance) and high reliability under high temperature conditions using the electroconductive polymer as a solid electrolyte. <P>SOLUTION: The dispersion liquid of the electroconductive polymer is produced by performing electrolytic oxidative polymerization of a monomer in water or in aqueous liquor comprising a liquid mixture of water and a water-miscible solvent, in the presence of a polymer dopant while isolating an anode from a cathode using a separator. The electroconductive polymer is obtained by drying the resulting dispersion liquid of an electroconductive polymer. The antistatic film and the solid electrolytic capacitor are constituted by using the electroconductive polymer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a dispersion of a conductive polymer, a dispersion of a conductive polymer produced thereby, a conductive polymer obtained by drying the dispersion of the conductive polymer, and the conductive The present invention relates to an antistatic film and an antistatic sheet using a conductive polymer as a conductor, and a solid electrolytic capacitor using the conductive polymer as a solid electrolyte.

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

  As the conductive polymer in this application, for example, a polymer synthesized by oxidative polymerization of a polymerizable monomer such as thiophene or a derivative thereof is used.

  As a dopant when performing oxidative polymerization of a polymerizable monomer such as thiophene or a derivative thereof, particularly chemical oxidative polymerization, organic sulfonic acid is mainly used, and among them, aromatic sulfonic acid is said to be suitable. Transition metals are used as oxidants, among which ferric iron is said to be suitable. Usually, ferric salts of aromatic sulfonic acids are chemically oxidative polymerization of polymerizable monomers such as thiophene or its derivatives. It is used as an oxidant and dopant in the process.

  And among the ferric salts of aromatic sulfonic acids, it is said that ferric salts of toluene sulfonic acid and ferric salts of methoxybenzene sulfonic acid are particularly useful, and conductive polymers using them. It can be synthesized by mixing those oxidizing agent / dopant with a polymerizable monomer such as thiophene or a derivative thereof, and is reported to be simple and suitable for industrialization (Patent Document 1, Patent Document) 2).

  However, the conductive polymer obtained using ferric toluenesulfonate as an oxidizing agent and dopant does not have sufficiently satisfactory characteristics in terms of initial resistance and heat resistance, and methoxybenzenesulfonic acid. The conductive polymer obtained using ferric salt as an oxidant and dopant has lower initial resistance and excellent heat resistance than the conductive polymer using ferric toluenesulfonate. Even so, satisfactory characteristics were not obtained.

  This is because toluenesulfonic acid ferric salt and methoxybenzenesulfonic acid ferric salt are solid, so they are generally used in a state of being dissolved in alcohol, but these solutions are precipitated during storage. This is because.

  In other words, when an alcohol solution of toluenesulfonic acid ferric salt or methoxybenzene ferric acid ferric salt in which precipitation has occurred is used, the uniformity is reduced, and solid electrolysis using the obtained conductive polymer is performed. This is because the ESR (equivalent series resistance) of the capacitor increases or the reliability under high temperature conditions decreases.

  In addition, when the obtained conductive polymer is used as a solid electrolyte of a solid electrolytic capacitor, the conductive polymer synthesized by a chemical oxidation polymerization method is usually not soluble in a solvent, so tantalum, niobium, aluminum, etc. There is a restriction that a conductive polymer layer must be directly formed on a dielectric layer of a capacitor element having an anode made of a porous body of the valve metal and a dielectric layer made of an oxide film of the valve metal. .

  Based on such a situation, solubilized conductive polymers have been actively studied (Patent Document 3). According to Patent Document 3, a dispersion of a conductive polymer can be obtained by mixing polystyrene sulfonic acid, ammonium persulfate, iron salt, ethylenedioxythiophene, and the like and chemically oxidizing ethylenedioxythiophene. It is reported. However, the conductive polymer obtained thereby cannot be said to have sufficiently high conductivity, and further improvement in conductivity is necessary for use as a solid electrolyte of a solid electrolytic capacitor.

  In addition, conductive polymers in which polyaniline is doped with phenolsulfonic acid novolak resin by chemical oxidative polymerization have been reported (Patent Documents 4 to 5). However, it cannot be said that this conductive polymer has a sufficiently high conductivity, and further improvement in conductivity is required for use as a solid electrolyte of a solid electrolytic capacitor.

  Furthermore, studies have been made on solubilized conductive polymers by electrolytic oxidation polymerization (Patent Documents 6 to 7). However, in these cases, there is a problem that it is difficult to use industrially because it requires a process of taking out and solubilizing the insoluble conductive polymer formed on the electrode.

JP 2003-160647 A JP 2004-265927 A Japanese Patent No. 2636968 Japanese Patent No. 3906071 JP 2007-277469 A Japanese Patent Laid-Open No. 1-161013 Japanese Patent Laid-Open No. 62-181328

  In view of the circumstances as described above, the present invention provides a conductive polymer having high conductivity and excellent heat resistance, and using the conductive polymer as a conductor, having high conductivity, An object of the present invention is to provide an antistatic film having excellent heat resistance, and to provide a solid electrolytic capacitor having low ESR and high reliability under high temperature conditions using the conductive polymer as a solid electrolyte. To do.

  As a result of intensive studies to solve the above problems, the present inventor has found that in the presence of a polymeric dopant, the monomer is mixed with water in an aqueous liquid or a mixture of water and a water-miscible solvent. When producing a dispersion of conductive polymer by electrolytic oxidative polymerization while separating the cathode from the separator, the conductive polymer is uniformly dispersed in water or aqueous liquid with almost no adhesion to the anode. And a conductive polymer dispersion is obtained in a state where the conductive polymer is prevented from coming into contact with the cathode by the separator and dedoping is prevented, and the conductive polymer dispersion is obtained from the conductive polymer dispersion. The obtained conductive polymer was found to have high conductivity and excellent heat resistance, and based on this, the present invention was completed.

  When the polymer dopant is at least one selected from the group consisting of polystyrene sulfonic acid, sulfonated polyester and a phenolsulfonic acid novolak resin having a repeating unit represented by the following general formula (I): The obtained conductive polymer can be made particularly high in conductivity and excellent in heat resistance, and is suitable for carrying out the present invention.

（式中のＲは水素またはメチル基である）

(Wherein R is hydrogen or a methyl group)

  The present invention relates to a method for producing a conductive polymer dispersion as described above, and is obtained by drying a conductive polymer dispersion produced thereby and the conductive polymer dispersion. The present invention also extends to a conductive polymer, an antistatic film and an antistatic sheet using the conductive polymer as a conductor, and a solid electrolytic capacitor using the conductive polymer as a solid electrolyte.

  The conductive polymer obtained from the dispersion of the conductive polymer of the present invention has high conductivity and excellent heat resistance. In addition, since the conductive polymer is synthesized by electrolytic oxidative polymerization, it contains a small amount of sulfate radicals based on an oxidant as seen in conductive polymer synthesized by chemical oxidative polymerization, and remains. There is little decrease in conductivity or transparency due to sulfate radicals.

  Therefore, an antistatic film, an antistatic resin, an antistatic sheet, etc. having high conductivity and excellent heat resistance can be obtained by using the conductive polymer as a conductor based on the characteristics of such a conductive polymer. it can. In addition, by using a conductive polymer having high conductivity and excellent heat resistance as a solid electrolyte, a solid electrolytic capacitor having low ESR and high reliability under high temperature conditions can be obtained.

It is a figure which shows typically the apparatus used in electrolytic oxidation polymerization by this invention by a cross-sectional display.

  In the practice of the present invention, the polymer dopant is, for example, at least one selected from the group consisting of polystyrenesulfonic acid, sulfonated polyester, and a phenolsulfonic acid novolak resin having a repeating unit represented by the general formula (I). Is preferably used. This is because these polymer dopants also function as excellent dispersants in the synthesis of conductive polymers, and evenly disperse the monomers and catalysts added as needed in water or aqueous liquids. In addition, since it is incorporated as a dopant in the polymer to be synthesized, it functions as an excellent dispersant, enabling the synthesis of a conductive polymer with a uniform composition, resulting in high conductivity and heat resistance. Is considered to contribute to the production of an excellent conductive polymer.

  As said polystyrene sulfonic acid, the thing whose weight average molecular weight is 10,000-1,000,000 is preferable, for example.

  That is, when the weight average molecular weight of the polystyrene sulfonic acid is smaller than 10,000, the conductivity of the obtained conductive polymer is lowered and the transparency may be deteriorated. Moreover, when the weight average molecular weight of the said polystyrene sulfonic acid is larger than 1,000,000, the viscosity of the dispersion liquid of an electroconductive composition will become high, and will become difficult to use in preparation of a solid electrolytic capacitor. The polystyrene sulfonic acid has a weight average molecular weight within the above range, preferably 20,000 or more, more preferably 40,000 or more, and preferably 800,000 or less. More preferable is 1,000 or less.

  The sulfonated polyester is a polycondensation polymer of dicarboxybenzenesulfonic acid diester such as sulfoisophthalic acid ester or sulfoterephthalic acid ester and alkylene glycol in the presence of a catalyst such as antimony oxide or zinc oxide. The sulfonated polyester preferably has a weight average molecular weight of 5,000 to 300,000.

  That is, when the weight average molecular weight of the sulfonated polyester is smaller than 5,000, the conductivity of the obtained conductive polymer is lowered and the transparency may be deteriorated. In addition, when the weight average molecular weight of the sulfonated polyester is larger than 300,000, the viscosity of the conductive polymer dispersion becomes high, making it difficult to use in the production of a solid electrolytic capacitor or the like. The sulfonated polyester preferably has a weight average molecular weight within the above range of 10,000 or more, more preferably 20,000 or more, and preferably 100,000 or less. More preferable is 1,000 or less.

  And as a phenolsulfonic acid novolak resin represented by the said general formula (I), that whose weight average molecular weight is 5,000-500,000 is preferable. This is based on the following reason.

  That is, when the weight average molecular weight of the phenolsulfonic acid novolak resin is less than 5,000, the conductivity of the obtained conductive polymer is lowered and the transparency may be deteriorated. Moreover, when the weight average molecular weight of the said phenolsulfonic acid novolak resin is larger than 500,000, the viscosity of the dispersion liquid of a conductive polymer will become high, and it will become difficult to use it for manufacture of a solid electrolytic capacitor etc. The phenol sulfonic acid novolak resin has a weight average molecular weight within the above range, preferably 5,000 or more, more preferably 10,000 or more, and preferably 400,000 or less. 80,000 or less is more preferable.

  The conductive polymer dispersion preferably contains a high boiling point solvent. This is because the film forming property of the obtained conductive polymer can be improved by containing a high boiling point solvent, and thereby the conductivity can be improved. The reason why the conductivity of the conductive polymer can be improved by including the high-boiling solvent in this way is not necessarily clear at present, but for example, a conductive polymer dispersion is used as a base material. When applied and dried, the layer density in the thickness direction is increased when the high boiling point solvent escapes, thereby reducing the interplanar spacing between the conductive polymers and increasing the conductivity of the conductive polymers. it is conceivable that.

  The high boiling point solvent preferably has a boiling point of 150 ° C. or higher. Specific examples of such a high boiling point solvent include dimethyl sulfoxide (boiling point 189 ° C.), γ-butyrolactone (boiling point 204 ° C.), sulfolane ( Examples include boiling point 285 ° C., N-methylpyrrolidone (boiling point 202 ° C.), dimethyl sulfone (boiling point 233 ° C.), ethylene glycol (boiling point 198 ° C.), diethylene glycol (boiling point 244 ° C.), and dimethyl sulfoxide is particularly preferable. The content of the high-boiling solvent is 5 to 3,000% on a mass basis with respect to the conductive polymer in the dispersion (that is, the high-boiling solvent is 5% based on 100 parts by mass of the conductive polymer). To 3,000 parts by mass), and particularly preferably 20 to 700%. When the content of the high-boiling solvent is less than the above, the film forming property of the conductive polymer is lowered, and as a result, the action of improving the conductivity of the conductive polymer is lowered, and the content of the high-boiling solvent is reduced. When the amount is more than the above, it takes time to dry the dispersion, and on the contrary, there is a possibility of causing a decrease in conductivity.

  In addition, since content of the conductive polymer in a dispersion influences workability | operativity etc. at the time of drying the dispersion and making it into a film form etc., about 1-10 mass% is preferable normally. In other words, when the content of the conductive polymer is less than the above, it takes time to dry, and when the content of the conductive polymer is more than the above, the viscosity becomes high and the coating is performed. Workability may be reduced.

  Most of the dried product obtained by drying the dispersion containing the high boiling point solvent is a conductive polymer because the high boiling point solvent is almost evaporated by heating during drying. However, depending on the evaporation of the high-boiling solvent, it may be possible that some of the high-boiling solvent may remain. However, in this document, it is expressed as a conductive polymer including the case where such a high-boiling solvent remains. I will do it.

  In the present invention, as a monomer for synthesizing a conductive polymer by electrolytic oxidation polymerization, at least one polymerizable monomer selected from the group consisting of thiophene or a derivative thereof, pyrrole or a derivative thereof, and aniline or a derivative thereof is used. However, examples of the thiophene derivatives include 3,4-ethylenedioxythiophene, 3-alkylthiophene, 3-alkoxythiophene, 3-alkyl-4-alkoxythiophene, 3,4-alkylthiophene, 3,4- Examples of pyrrole derivatives include 3,4-alkylpyrrole and 3,4-alkoxypyrrole. Examples of aniline derivatives include 2-alkylaniline and 2-alkoxyaniline. Etc. The alkyl group or alkoxy group preferably has 1 to 16 carbon atoms.

  Electrolytic oxidation polymerization in the synthesis of the conductive polymer is performed in water or an aqueous liquid composed of a mixture of water and a water-miscible solvent. At that time, as the polymer dopant, as described above, it is preferable to use polystyrene sulfonic acid, sulfonated polyester, phenolsulfonic acid novolak resin having a repeating unit represented by the general formula (I), or the like.

  Examples of the water-miscible solvent constituting the aqueous liquid include methanol, ethanol, propanol, acetone, acetonitrile, and the like. The mixing ratio of these water-miscible solvents with water is 50 in the entire aqueous liquid. The mass% or less is preferable.

  The amount of the dopant or polymerizable monomer used in the electrolytic oxidation polymerization is not particularly limited. For example, polystyrene sulfonic acid is used as the dopant, and thiophene derivative 3,4-ethylene diene is used as the polymerizable monomer. The case of using oxythiophene will be described as an example. The use ratio thereof is preferably a mass ratio of 3,4-ethylenedioxythiophene of 0.05 or more with respect to polystyrenesulfonic acid 1, 1 or more is more preferable, 5 or less is preferable, and 1 or less is more preferable. This is almost the same when other materials are used as the dopant and other materials are used as the polymerizable monomer.

The electrolytic oxidation polymerization can be performed at a constant current or a constant voltage. For example, when electrolytic oxidation polymerization is performed at a constant current, the current value is preferably 0.05 to 10 mA / cm ^{2 and} is 0.2 mA / cm within the above range. cm ² or more is more preferable. When electrolytic oxidation polymerization is performed at a constant voltage, the voltage is preferably 0.5 to 10 V, and more preferably 1.5 V or more within the above range. The temperature during electrolytic oxidation polymerization is preferably 5 to 95 ° C, more preferably 10 ° C or higher, and more preferably 30 ° C or lower. The polymerization time is preferably 1 to 72 hours, more preferably 8 hours or more, and more preferably 24 hours or less. The distance between the electrodes (that is, the distance between the surfaces where the anode and the cathode face each other through the separator) is preferably 1 to 15 cm. That is, when the distance between the electrodes becomes wider than the above (that is, when the distance between the anode and the cathode becomes longer), the reason is not clear, but the conductivity of the obtained conductive polymer is lowered, and the distance between the electrodes If the distance is narrower than the above, the liquid flow may deteriorate and the conductive polymer may be solidified. In the electrolytic oxidation polymerization, ferrous sulfate or ferric sulfate may be added as a catalyst. When the electrolytic oxidation polymerization is carried out in water or an aqueous solution containing the iron ions of these catalysts, polymerization of the monomer is promoted.

  In the present invention, the electrolytic oxidation polymerization is performed by separating the anode and the cathode with a separator, but is limited to a specific one or a specific means except that the separator separates the anode and the cathode. Without limitation, for example, other members such as an anode and a cathode can be used in the same manner as in the past, and can be carried out by the same means as in the past.

  The separator is not particularly limited as long as it does not allow the generated conductive polymer to pass through functionally in order to prevent the conductive polymer generated around the anode from coming into contact with the cathode and undoping. For example, those having a fractional molecular weight of 50,000 or less (that is, those having a molecular weight of 50,000 or less are allowed to pass but those having a molecular weight of 50,000 or less are not allowed to pass), Those having a molecular weight of 10,000 or less are preferred. From the viewpoint of material and the like, as this separator, for example, a porous film made of a polymer such as regenerated cellulose, polyethersulfone or polyacrylonitrile is preferable, and a porous film made of regenerated cellulose is particularly preferable.

  Here, an outline of an apparatus for performing electrolytic oxidation polymerization while separating the anode and the cathode with a separator will be described with reference to FIG.

  FIG. 1 is a diagram schematically showing a cross-sectional view of an apparatus used for electrolytic oxidation polymerization in the present invention. In FIG. 1, 1 is an anode, and this anode 1 is a bottomed cylindrical shape made of stainless steel. And also serves as an electrolytic cell in which electrolytic oxidation polymerization is performed. The cathode 2 is composed of a stainless steel plate. In the case shown in FIG. 1, two cathodes 2 are provided, but only one may be used, and in order to allow electrolytic oxidation polymerization to proceed rapidly. Many more may be provided. The separator 3 has a bottomed cylindrical shape, and the lower side of the cathode 2 is placed in the bottomed cylindrical separator 3. And the distance between the electrodes between the anode 1 and the cathode 2 is preferably 1 to 15 cm as described above.

  4 is a stirring blade made of stainless steel. Although not shown in FIG. 1, the upper part of the cathode 2 is electrically connected to the power source through a lead wire, and the anode 1 is also electrically connected to the power source through a lead wire. ing.

  The water or aqueous liquid containing the polymer dopant acts as an electrolyte because the dopant has a function as an electrolyte, and the electrolyte 5 containing the polymer dopant is filled in the anode 1 that also serves as an electrolytic cell. The electrolytic solution 5 is also filled in the separator 3 and is in contact with the cathode 2. When the stirring blade 4 is rotated and the monomer is dropped into the anode 1 so as not to contact the cathode 2 (that is, dropped outside the separator 3), electrolytic oxidation polymerization is started, and the monomer is contained in the electrolytic solution 5. A conductive polymer is synthesized by polymerizing while taking in a polymer dopant, and is dispersed in the electrolyte without sticking to the peripheral wall of the stainless steel container constituting the anode 1. The conductive polymer is synthesized in a state in which contact of the molecule with the cathode 2 is prevented and dedoping of the conductive polymer is prevented.

  The conductive polymer obtained as described above is obtained immediately after the polymerization and dispersed in water or an aqueous liquid, and contains an iron sulfate salt used as a catalyst or a decomposition product thereof. Therefore, the conductive polymer dispersion containing the impurities is dispersed in a dispersing machine such as an ultrasonic homogenizer or a planetary ball mill, and then the metal component is removed with a cation exchange resin. The particle size of the conductive polymer at this time is preferably 100 μm or less, and particularly preferably 10 μm or less. Thereafter, sulfuric acid produced by decomposition of the catalyst is removed by an ethanol precipitation method, an ultrafiltration method, an anion exchange resin, or the like, and a high boiling point solvent is added as necessary.

  Since the conductive polymer obtained from the dispersion of the conductive polymer of the present invention has high conductivity, excellent heat resistance, and excellent transparency, an antistatic film, an antistatic cloth, an antistatic resin, etc. It can be suitably used as a conductor of the antistatic material. In addition, since the above conductive polymer has high conductivity and excellent heat resistance, it can be used as a solid electrolyte for solid electrolytic capacitors such as aluminum solid electrolytic capacitors, tantalum solid electrolytic capacitors, and niobium solid electrolytic capacitors. A solid electrolytic capacitor that is suitably used, has low ESR, and high reliability under high temperature conditions can be provided.

  Furthermore, the conductive polymer obtained from the dispersion of the conductive polymer of the present invention uses the characteristics that it has high conductivity and excellent heat resistance, so that the solid electrolyte and the charge of the solid electrolytic capacitor are charged. In addition to the conductor of the preventive material, it can also be suitably used as a positive electrode active material for batteries, a base resin for anti-corrosion paints, and the like.

  As described above, when the conductive polymer obtained from the dispersion of the conductive polymer of the present invention is used as a conductor of an antistatic material or a solid electrolyte of a solid electrolytic capacitor, it can be used as it is. However, it is suitable to use the conductive polymer obtained by dispersing the conductive polymer in water or an aqueous liquid and then drying it as a conductor or a solid electrolyte.

  To produce an antistatic film using a conductive polymer obtained from the dispersion of the conductive polymer of the present invention (hereinafter referred to as “conductive polymer according to the present invention”) as a conductor, a base sheet The conductive polymer dispersion of the present invention is applied to the substrate, or the substrate sheet is immersed in the conductive polymer dispersion of the present invention, pulled up, and dried to form a film. However, the antistatic film formed on one or both sides of the base sheet is not peeled off from the base sheet, and the base sheet is used as a support material. As a sheet, it may be more suitable for use. In order to produce an antistatic cloth using the conductive polymer according to the present invention as a conductor, the dispersion of the conductive polymer of the present invention is applied to the cloth, or the cloth is coated with the conductive polymer. After dipping in a dispersion liquid, pulling up and drying. In preparing the antistatic sheet or the antistatic cloth as described above, if the binder resin is added to the dispersion of the conductive polymer of the present invention, the conductive polymer with respect to the base sheet or the cloth is added. Since adhesion can be improved, it is preferable. It is also preferable to add a binder to the conductive polymer dispersion as described above even when the conductive polymer is used as a solid electrolyte of a solid electrolytic capacitor.

  Examples of the binder resin as described above include polyurethane, polyester, acrylic resin, polyamide, polyimide, epoxy resin, polyacrylonitrile resin, polymethacrylonitrile resin, polystyrene resin, novolac resin, silane coupling agent, and the like. Polyester, polyurethane, acrylic resin and the like are particularly preferable. Moreover, since the electroconductivity of a conductive polymer can be improved when the sulfone group is added like sulfonated polyallyl, sulfonated polyvinyl, and sulfonated polystyrene, it is more preferable.

  The binder resin or other resin is added to the conductive polymer dispersion of the present invention and dried to obtain an antistatic resin. When the conductive polymer composition according to the present invention is used as a solid electrolytic capacitor, the solid electrolytic capacitor can be produced as follows.

  First, when the conductive polymer according to the present invention is used as a solid electrolyte such as a tantalum solid electrolytic capacitor, a niobium solid electrolytic capacitor, or a laminated aluminum solid electrolytic capacitor, an anode made of a porous body of a valve metal such as tantalum, niobium, or aluminum And by repeating the steps of immersing the capacitor element having a dielectric layer made of an oxide film of the valve metal in the conductive polymer dispersion of the present invention, taking it out, and drying it, thereby conducting the conductive polymer. Solid electrolyte capacitors such as tantalum solid electrolytic capacitors, niobium solid electrolytic capacitors, and multilayer aluminum solid electrolytic capacitors are manufactured by forming a solid electrolyte layer made of, applying carbon paste and silver paste, drying and then packaging can do.

  In addition, for example, the organic sulfonate is used as a dopant, the capacitor element is immersed in a liquid containing a polymerizable monomer and an oxidizing agent, and then taken out, then polymerized at room temperature, immersed in water, taken out, and washed. Then, after the conductive polymer is synthesized by drying, the solid electrolyte layer may be formed by repeating the steps of immersing the whole in the dispersion of the conductive polymer of the present invention, taking it out and drying it. Moreover, you may make it the reverse form.

  Then, the element covered with the conductive polymer is covered with carbon paste and silver paste, and then packaged to produce a tantalum solid electrolytic capacitor, niobium solid electrolytic capacitor, laminated aluminum solid electrolytic capacitor, etc. You can also

  When the conductive polymer according to the present invention is used as a solid electrolyte of a wound aluminum solid electrolytic capacitor, the surface of the aluminum foil is subjected to etching treatment and then lead to the anode on which the dielectric layer is formed by chemical conversion treatment. A terminal is attached, a lead terminal is attached to a cathode made of aluminum foil, and the anode with the lead terminal and the cathode are wound through a separator to produce a capacitor element. Immerse in a molecular dispersion, take it out, dry it, and then remove the conductive polymer that does not enter the pores formed by etching the aluminum foil, soak it in pure water, take it out, and dry it. After repeating these operations, a wound aluminum solid electrolytic capacitor can be produced by packaging with an exterior material.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited only to those illustrated in these examples. In the following examples and the like,% in the case of indicating the concentration and amount used is based on mass unless otherwise indicated.

Example 1
As the apparatus used for electrolytic oxidation polymerization, the apparatus shown in FIG. 1 described above was used. Each member of the electrolytic oxidation polymerization apparatus will be described as follows.

  The anode 1 is composed of a stainless steel bottomed cylindrical container, and the cathode 2 is composed of a strip-shaped stainless steel plate having a thickness of 4 mm, a length of 500 mm, and a width of 135 mm. Two cathodes 2 are used, and both of them are placed in a bottomed cylindrical separator 3 at the lower side, and are immersed in an electrolyte solution 5 described later up to 250 mm from the lower end. is doing. Separator 3 is a bottomed cylinder with a cellulose tube of a molecular weight cut off of 14,000, model number UC C-150-100 manufactured by Sanko Junyaku Co., Ltd. (formed in a tube shape with a porous film made of regenerated cellulose). The formed one is used, and two separators 3 are used in accordance with the number of cathodes 2. The distance between the anode 1 and the cathode 2 (distance between the electrodes) was in the range of 8 to 10 cm from the anode 1 to either cathode 2 although there was a slight difference depending on the parts facing each other. .

  The stirring blade 4 is made of stainless steel, and the stirring blade 4 is provided at the center of the anode 1 formed of a stainless steel container. The two cathodes 2 have a bottomed cylinder on their lower sides. In the state of being put in the separator 3, the stirring blade 4 is placed in the anode 1 so as to be opposed to both sides with the center.

  30 kg of a 3% aqueous solution of polystyrene sulfonic acid (Taika Co., Ltd., weight average molecular weight 100,000) as a dopant is placed in an anode 1 composed of a stainless steel container, and there is 15 g of ferrous sulfate heptahydrate. Was added, stirred, and mixed uniformly to obtain an electrolyte solution 5 containing a dopant. The electrolytic solution 5 containing this dopant passes through the separator 3 and is also in contact with the cathode 2.

In this state, 200 mL of 3,4-ethylenedioxythiophene as a polymerizable monomer is dropped on the electrolyte 5 outside the separator 3 while not contacting the cathode 2, and 0.2 mA at room temperature. Electrolytic oxidation polymerization was carried out at a constant current of / cm ² for 30 hours. By this electrolytic oxidation polymerization, the monomer 3,4-ethylenedioxythiophene was polymerized while incorporating the dopant in the electrolytic solution 5, and a conductive polymer having polystyrene sulfonic acid as a dopant was synthesized.

  After the electrolytic oxidation polymerization, it was diluted twice with water, and then subjected to a dispersion treatment for 12 hours with an ultrasonic homogenizer (US-T1200, manufactured by Nippon Seiki Co., Ltd.). Thereafter, 5 kg of Cation Exchange Resin Amberlite 120B (trade name) manufactured by Organo Corp. was added and stirred for 1 hour. Subsequently, filter paper No. manufactured by Toyo Filter Paper Co., Ltd. The mixture was filtered through 131, and the treatment with this cation exchange resin and filtration were repeated three times to remove all cation components such as iron ions in the liquid.

  The liquid after the above treatment is passed through a filter having a pore size of 1 μm, and the passing liquid is treated with an ultrafiltration membrane (ACP-2053 (trade name) manufactured by Asahi Kasei Chemicals Corporation, molecular weight cut off 10,000) to release in the liquid. By removing the low molecular weight component, a conductive polymer dispersion in which polystyrenesulfonic acid was incorporated as a dopant in a 3,4-ethylenedioxythiophene polymer was obtained.

  Water was added to the dispersion of this conductive polymer to adjust the concentration to 3%, and 1 kg of dimethyl sulfoxide as a high boiling point solvent was added to 25 kg of the 3% solution (133% on a mass basis with respect to the conductive polymer). ) Added.

Example 2
Instead of polystyrene sulfonic acid, sulfonated polyester [Plus Coat Z-561 (trade name), weight average molecular weight 27,000, manufactured by Kyoyo Chemical Industry Co., Ltd.] is used as a dopant, and the amount of ferrous sulfate and heptahydrate All operations were the same as in Example 1 except that the amount was changed from 15 g to 2 g. Note that dimethyl sulfoxide was added to the conductive polymer dispersion obtained in Example 2 as a high-boiling solvent as in Example 1.

Comparative Example 1
The same operation as in Example 1 was performed except that no separator was used.

Comparative Example 2
The same operation as in Example 2 was performed except that no separator was used.

[Evaluation as conductive polymer]
50 μL of each of the conductive polymer dispersions of Examples 1-2 and Comparative Examples 1-2 above was dropped on a 2.8 cm × 4.8 cm glass plate. After uniformizing with an 8 bar coater, drying at 60 ° C. for 10 minutes, followed by drying at 150 ° C. for 10 minutes to form a conductive polymer film on the glass plate, the conductive polymer film Was measured at room temperature (about 25 ° C.) with a 4-probe conductivity meter [MCP-T600 (trade name) manufactured by Mitsubishi Chemical Corporation] according to JIS K 7194. The results are shown in Table 1. In addition, measurement is performed for each sample for five points, and the numerical values shown in Table 1 are obtained by calculating an average value of the five points and rounding off the decimals.

  As shown in Table 1, Examples 1-2 were higher in electrical conductivity and superior in electrical conductivity than Comparative Examples 1-2.

[Evaluation as antistatic film]
Examples 3-4 and Comparative Examples 3-4
For the conductive polymer dispersion of Example 1 and Comparative Example 1, a sulfonated polyester resin [Plus Coat Z-561 (trade name) manufactured by Kyoyo Chemical Industry Co., Ltd.] as a binder resin was applied to the conductive polymer. Then, the resin components were added so as to be about 150% and stirred. 50 μL of the dispersion containing the sulfonated polyester resin was dropped on a 2.8 cm × 4.8 cm polyethylene sheet. After uniformizing with an 8 bar coater, drying at 60 ° C. for 10 minutes, followed by drying at 150 ° C. for 1 minute, the antistatics of Example 3 and Comparative Example 3 using the respective conductive polymers as conductors A film was prepared.

  Also, the conductive polymer dispersions of Example 2 and Comparative Example 2 were each dropped on a 2.8 cm × 4.8 cm polyethylene sheet in the same manner as described above, and the same operation was performed thereafter. Thus, antistatic films of Example 4 and Comparative Example 4 were produced.

  The surface resistance of the obtained antistatic films of Examples 3 to 4 and Comparative Examples 3 to 4 was measured at room temperature (about 25 ° C.) in accordance with JIS K 7194. MCP-T600 (trade name)], and visible light transmittance at a wavelength of 400 to 700 nm was measured using UV-VIS-NIR RECORDING SPECTROTOPOMETER [Shimadzu Corporation UV3100 (trade name)]. The results are shown in Table 2 together with the types of conductive polymers using the results. In addition, measurement is performed for each sample for five points, and the numerical values shown in Table 3 are obtained by calculating an average value of the five points and rounding off the decimals.

  As shown in Table 2, with respect to the transmittance with respect to visible light, Examples 3 to 4 show a high transmittance of 91%, as in Comparative Examples 3 to 4, and have high transparency. Although there was no difference between 3-4 and Comparative Examples 3-4, about surface resistance, Examples 3-4 had a small surface resistance compared with Comparative Examples 3-4.

[Evaluation as a solid electrolytic capacitor]
Example 5
In a state where the tantalum sintered body is immersed in a phosphoric acid solution having a concentration of 0.1%, chemical conversion treatment is performed by applying a voltage of 20 V, and an oxide film is formed on the surface of the tantalum sintered body to form a dielectric layer. Configured. Next, the tantalum sintered body was immersed in an ethanol solution of 3,4-ethylenedioxythiophene having a concentration of 35%, taken out after 1 minute, and left for 5 minutes. Thereafter, in an oxidizing agent / dopant solution consisting of a mixture prepared by mixing a 50% aqueous phenol butylamine sulfonate solution (pH 5) and a 30% aqueous ammonium persulfate solution in a mass ratio of 1: 1. It was immersed, taken out after 30 seconds, allowed to stand at room temperature for 30 minutes, and then heated at 50 ° C. for 10 minutes for polymerization. Thereafter, the tantalum sintered body was immersed in water and allowed to stand for 30 minutes, then taken out and dried at 70 ° C. for 30 minutes. After repeating these operations 6 times, the tantalum sintered body was immersed in the conductive polymer dispersion of Example 1, taken out after 30 seconds, and dried at 70 ° C. for 30 minutes. This operation was repeated three times, and then allowed to stand at 150 ° C. for 60 minutes to form a solid electrolyte made of a conductive polymer. Thereafter, the solid electrolyte layer was covered with carbon paste and silver paste to produce a tantalum solid electrolytic capacitor.

Example 6
A tantalum solid electrolytic capacitor was produced in the same manner as in Example 5 except that the conductive polymer dispersion of Example 2 was used instead of the conductive polymer dispersion of Example 1. .

Comparative Example 5
A tantalum solid electrolytic capacitor was produced in the same manner as in Example 5 except that the conductive polymer dispersion of Comparative Example 1 was used instead of the conductive polymer dispersion of Example 1. .

Comparative Example 6
A tantalum solid electrolytic capacitor was produced in the same manner as in Example 5 except that the conductive polymer dispersion of Comparative Example 2 was used instead of the conductive polymer dispersion of Example 1. .

  For the tantalum solid electrolytic capacitors of Examples 5 to 6 and Comparative Examples 5 to 6 produced as described above, their ESR and capacitance were measured. The results are shown in Table 3. In addition, the measuring method of ESR and an electrostatic capacitance is as showing below. The ESR is measured using an LCR meter (4284A) manufactured by HEWLETT PACKARD at 25 ° C. and 100 kHz, and the capacitance is measured using an LCR meter (4284A) manufactured by HEWLETT PACKARD at 25 ° C. The electrostatic capacity was measured at 120 Hz. These measurements were performed on 10 samples for each sample, and the ESR values and capacitance values shown in Table 3 were obtained by calculating the average value of the 10 samples and rounding off the decimals.

  As shown in Table 3, Examples 5-6 had smaller ESR than Comparative Examples 5-6.

1 Anode 2 Cathode 3 Separator

Claims (9)

  In the presence of a polymeric dopant, the monomer can be electroconductively polymerized by electrolytic oxidation polymerization in water or an aqueous liquid consisting of a mixture of water and a water-miscible solvent, with the anode and cathode separated by a separator. A method for producing a dispersion of a conductive polymer, comprising producing a dispersion of molecules.   The method for producing a conductive polymer dispersion according to claim 1, wherein the monomer is thiophene or a derivative thereof. 2. The conductivity according to claim 1, wherein the polymer dopant is at least one selected from the group consisting of polystyrene sulfonic acid, sulfonated polyester, and a phenol sulfonic acid novolak resin having a repeating unit represented by the general formula (I). A method for producing a polymer dispersion.

(Wherein R is hydrogen or a methyl group)   A conductive polymer dispersion produced by the method according to claim 1.   5. The conductive polymer dispersion according to claim 4, wherein a high boiling point solvent is added.   A conductive polymer obtained by drying a dispersion of the conductive polymer according to claim 4.   An antistatic film comprising the conductive polymer according to claim 6 as a conductor.   An antistatic sheet comprising the antistatic film according to claim 7 formed on at least one surface of a sheet base material.   A solid electrolytic capacitor comprising the conductive polymer according to claim 6 as a solid electrolyte.

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