JP2011009568A - Method for forming electrolyte for conductive polymer capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a conductive polymer electrolyte and a method for manufacturing a conductive polymer capacitor equipped with the electrolyte, which satisfy all of the low ESR, the low leakage current, and the high capacity.SOLUTION: The method for forming an electrolyte for a conductive polymer aluminum electrolyte capacitor includes the following process (1a) and process (2a), the process (1a) and/or the process (2a) being performed under the existence of ionic liquid, wherein (1a) is the process to in-situ polymerize conductive polymer monomer, and (2a) is the process to impregnate a conductive polymer dispersion liquid (B) after the process (1a).

Description

  The present invention relates to a method for forming an electrolyte for a conductive polymer capacitor having both low ESR, low leakage current, and large capacity, and a method for manufacturing a conductive polymer capacitor including the electrolyte.

In recent years, the market for solid electrolytic capacitors using a conductive polymer as an electrolyte is expanding due to their excellent ESR characteristics. Solid electrolytic capacitors typically use solid conductive polymers such as polypyrrole or polythiophene derivatives as electrolytes, and these conductive polymers are electrolytic capacitors using conventional liquids as electrolytes. Its electrical conductivity (that is, electronic conductivity) is much higher than that of the capacitor, and particularly exhibits excellent characteristics as a capacitor for high-frequency circuits. In addition to the low ESR described above, solid electrolytic capacitors are required to have characteristics of reducing leakage current and increasing capacity.

  As an approach for solving these problems, in Patent Document 1, poly (3,4-ethylenedioxythiophene) (hereinafter PEDOT) obtained by chemical polymerization of 3,4-ethylenedioxythiophene (hereinafter abbreviated as EDOT) is disclosed. It is reported that low ESR and reduction of leakage current can be realized by applying a dispersion containing polymer particles to the outer layer coating. Further, in Patent Document 2, further studies are made on the formation conditions of the solid electrolyte in Patent Document 1, and characteristics are improved by improving the adhesion between the electrolyte and the outer layer coating polymer. Subsequently, in Patent Document 3 and Patent Document 4, the polymer particle diameter to be applied to the outer layer coating is examined by further investigation with respect to Patent Document 2, and the characteristics are improved by improving the coverage of the outer layer with the polymer. Yes.

  However, in any of the methods, since the polymer used as the electrolyte is solid, the electrode is not sufficiently filled with the electrolyte, and as a result, characteristics satisfying the market requirements can be obtained in terms of capacity improvement. However, a method for forming an electrolyte that satisfies all of low ESR, low leakage current, and high capacity, and a capacitor obtained by the manufacturing method are desired.

  In addition, the efforts of Patent Documents 1 to 4 are intended for sintered elements of tantalum and niobium, and are not mentioned regarding application to wound elements represented by aluminum and the like. Has pointed out the possibility that the results obtained with the sintered body may not be reproduced.

  In order to solve such a problem, the present inventors expect that the ionic liquid behaves in the same manner as the conventional electrolytic solution, and already uses an electrolyte composed of the ionic liquid and the conductive polymer, It has also been clarified that the capacity development rate can be improved for a conductive polymer capacitor (Patent Document 5). However, low ESR, low leakage current, and high capacity have not been satisfied.

JP 2005-123630 A JP 2005-322917 A JP 2006-295184 A JP 2007-27767 A International Publication WO2006 / 088033 Pamphlet

  It is an object of the present invention to provide a method for forming a conductive polymer electrolyte that satisfies all of low ESR, low leakage current, and high capacity, and a method for manufacturing a conductive polymer capacitor including the electrolyte.

  As a result of intensive studies in view of the above, the present inventors have conducted in-situ polymerization of a conductive polymer monomer in the formation of an electrolyte for a conductive polymer aluminum electrolytic capacitor, and conductive polymer dispersion after in-situ polymerization. When at least one of the steps of impregnating the liquid is carried out in the presence of an ionic liquid, it has been found that an electrolyte satisfying all of low ESR, low leakage current and high capacity can be formed, and the present invention has been completed.

That is, the present invention
[1] A method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor, comprising the following steps (1a) and (2a), wherein steps (1a) and / or (2a) are performed in the presence of an ionic liquid:
(1a) a step of in situ polymerization of a conductive polymer monomer;
(2a) Step of impregnating the conductive polymer dispersion (B) after the step (1a),
[2] The method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor according to the above [1], further comprising (1b) a step of performing cleaning between the steps (1a) and (2a). .
[3] The method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor according to the above [1] or [2], wherein the in situ polymerization is chemical polymerization and / or electrolytic polymerization.
[4] The conductive polymer monomer is at least one selected from the group consisting of thiophene, thiophene derivatives, pyrrole, pyrrole derivatives, aniline and aniline derivatives. A method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor as described.
[5] The conductive polymer (D) contained in the conductive polymer dispersion (B) is at least one selected from the group consisting of thiophene, thiophene derivatives, pyrrole, pyrrole derivatives, aniline and aniline derivatives. The method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor according to any one of the above [1] to [4], which is a product of polymerization.
[6] The method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor according to any one of the above [1] to [5], wherein the anion component of the ionic liquid is a carboxylate anion,
[7] The cation component of the ionic liquid is ammonium ion, imidazolium ion, pyridinium ion, pyrrolidinium ion, pyrrolium ion, pyrazinium ion, pyrimidinium ion, triazonium ion, triazinium ion, triazine ion, key Selected from the group consisting of norinium ion, isoquinolinium ion, indolinium ion, quinoxalinium ion, piperazinium ion, oxazolinium ion, thiazolinium ion, morpholinium ion, piperazine ion and derivatives thereof A method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor according to any one of [1] to [6], wherein
[8] A method for producing a conductive polymer aluminum electrolytic capacitor, including the method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor according to any one of [1] to [7],
About.

  According to the production method of the present invention, an electrolyte satisfying all of low ESR, low leakage current, and high capacity suitable for a conductive polymer aluminum electrolytic capacitor can be obtained.

The mercury cell used for impedance measurement is shown.

  Hereinafter, embodiments of the present invention will be described in detail.

  First, the step (1a) of the present invention, that is, in situ polymerization using the solution (A) containing a conductive polymer monomer will be described.

  The step (1a) of the present invention is a first-stage method for forming an electrolyte in the capacitor element, and is performed for the purpose of filling the conductive polymer as the electrolyte into the pores of the electrode.

  In the present invention, step (1a) may be performed in the presence of an ionic liquid.

  An ionic liquid, also called a room temperature molten salt, refers to a liquid that is liquid at room temperature despite being composed only of ions, and is composed of a combination of a cation such as imidazolium and an appropriate anion. The ionic liquid is not partially ionized and dissociated like a normal organic solvent, but is considered to be formed from only ions and 100% ionized. As described above, the ionic liquid is usually a liquid at room temperature, but the ionic liquid used in the present invention does not necessarily have to be a liquid at room temperature, and becomes a liquid during the aging process or heat treatment of the capacitor. Any material that spreads and becomes a liquid by Joule heat generated during the repair of the dielectric oxide film may be used.

  Although it does not restrict | limit especially as an ionic liquid which can be used in this invention, The ionic liquid whose anion is a carboxylate anion, a sulfonate anion, an alkoxy sulfonate anion, a fluoro bromine anion, a fluoro boron anion, etc. is mentioned. Among these, from the viewpoint of life characteristics and capacity characteristics, an ionic liquid in which the anion is a carboxylate anion can be preferably used. More specifically, an ionic liquid having a formate anion and / or general formula (1);

An ionic liquid having an anion represented by can be used. The anion represented by the formula (1) is paired with a cation described later to form a liquid salt at room temperature, that is, an ionic liquid.

In the formula (1), R ¹ and R ² are each independently a hydrogen atom, a protected or unprotected hydroxyl group, a protected or unprotected amino group, an alkoxy group, a nitro group, a cyano group, a carboxyl group, a halogen atom, A C1-C20 alkyl group which may form a chain, a branch or a ring and may have a substituent, a straight chain or a branch or a ring which may have a substituent C2-C20 alkenyl group, linear or branched or ring-forming optionally having C2-C20 alkynyl group, optionally having C6-C20 aryl A C4 to C20 heteroaryl group optionally having a substituent, a C7 to C20 aralkyl group optionally having a substituent, and a C4 to C20 heteroaryl optionally having a substituent Represents an aralkyl group, which may be the same or different from each other, and together may form a ring;

  In the present invention, “may have a substituent” means that it may be substituted with another atom or substituent. The “substituent” is not particularly limited as long as it does not adversely affect the reaction. Specifically, the hydroxyl group, alkyl group, alkoxy group, alkylthio group, nitro group, amino group, cyano group, carboxyl group, A halogen atom etc. are mentioned.

  The C1-C20 alkyl group which may form a straight chain, a branched chain or a ring and may have a substituent is not particularly limited, but for example, a methyl group, a hydroxymethyl group, an ethyl group N-propyl group, isopropyl group, cyclopropyl group, n-butyl group, sec-butyl group, tert-butyl group, cyclobutyl group, n-pentyl group, cyclopentyl group, n-hexyl group, n-heptyl group, cyclohexyl Groups, n-octyl groups, n-decyl groups, and the like, and those in which an arbitrary number of hydrogen atoms of these alkyl groups are substituted with fluorine atoms can be mentioned.

  Examples of the C2-C20 alkenyl group which may form a straight chain, a branched chain or a ring and may have a substituent include, for example, a vinyl group, a propenyl group, a styryl group, an isopropenyl group, a cyclopropenyl group, Examples include butenyl group, cyclobutenyl group, cyclopentenyl group, hexenyl group, cyclohexenyl group and the like.

  Examples of the C2-C6 alkynyl group which may form a straight chain, a branched chain or a ring and may have a substituent include, for example, an ethynyl group, a propynyl group, a phenylethynyl group, a cyclopropylethynyl group, a butynyl group , A pentynyl group, a cyclobutylethynyl group, a hexynyl group, and the like.

  Examples of the aryl group which may have a substituent include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a terphenyl group, and a 3,4,5-trifluorophenyl group.

  Examples of the heteroaryl group which may have a substituent include, for example, pyrrolinyl group, pyridyl group, quinolyl group, imidazolyl group, furyl group, indolyl group, thienyl group, oxazolyl group, thiazolyl group, 2-phenylthiazolyl group. , 2-anisyl thiazolyl group and the like.

  Examples of the aralkyl group which may have a substituent include benzyl group, chlorobenzyl group, bromobenzyl group, salicyl group, α-hydroxybenzyl group, phenethyl group, α-hydroxyphenethyl group, naphthylmethyl group, anthracyl group. Examples include a senylmethyl group, a 3,5-difluorobenzyl group, and a trityl group.

  Examples of the heteroaralkyl group which may have a substituent include a pyridylmethyl group, a difluoropyridylmethyl group, a quinolylmethyl group, an indolylmethyl group, a furfuryl group, and a thienylmethyl group.

R ¹ and R ² may be combined to form a ring, and examples thereof include a cyclohexyl group and a phenyl group.

When R ¹ and / or R ² is a hydroxyl group or an amino group, or has a hydroxyl group or an amino group as a substituent, the hydroxyl group or amino group may be protected or unprotected. Although the protecting group is not particularly limited, for example, a general protecting group may be used, and examples thereof include those described in “PROTECTIVE GROUPS in ORGANIC SYNTHESIS THIRD EDITION” (page 17 WILEY-INTERSCIENCE). Specific examples of hydroxyl protecting groups include ether protecting groups such as methyl, methoxymethyl, methylthiomethyl, trimethylsilyl, and triethylsilyl groups, and ester protecting groups such as acetyl and chloroacetyl groups. Can be mentioned. Examples of amino protecting groups include benzyl, trityl, formyl, acetyl, chloroacetyl, tetrachloroacetyl, tetrafluoroacetyl, benzoyl, phenylacetoxy, methoxycarbonyl, ethoxycarbonyl, -Fluorenylmethoxycarbonyl group, t-butoxycarbonyl group, etc. are mentioned. From the viewpoint of ease of introduction and deprotection, among the above groups, benzyl, trityl, formyl, acetyl, chloroacetyl, tetrachloroacetyl, tetrafluoroacetyl, benzoyl, phenyl An acetoxy group, a 9-fluorenylmethoxycarbonyl group, and a t-butoxycarbonyl group;

  The cation component of the ionic liquid includes ammonium and its derivatives, imidazolium and its derivatives, pyridinium and its derivatives, pyrrolidinium and its derivatives, pyrrolinium and its derivatives, pyrazinium and its derivatives, pyrimidinium and its derivatives, triazonium and its derivatives, triazinium and its derivatives Derivatives thereof, triazine and derivatives thereof, quinolinium and derivatives thereof, isoquinolinium and derivatives thereof, indolinium and derivatives thereof, quinoxalinium and derivatives thereof, piperazinium and derivatives thereof, oxazolinium and derivatives thereof, thiazolinium and derivatives thereof, morpholinium and derivatives thereof , Piperazine and its derivatives. In view of the relatively low Tg, imidazolium derivatives are preferred, and the imidazolium derivatives are preferably diethyl imidazolium, ethyl butyl imidazolium and dimethyl imidazolium, particularly preferably ethyl methyl imidazolium and methyl butyl imidazolium. It is.

  In the present invention, these ionic liquids may be used alone or in combination of two or more.

  Since the ionic liquid has ionic conductivity but not electronic conductivity, it behaves as an insulator in the capacitor electrolyte. Therefore, since ESR characteristics tend to deteriorate when too much ionic liquid is added, the total amount of ionic liquid used is preferably 5 molar equivalents or less with respect to the conductive polymer monomer, more preferably 0. .01 molar equivalent or more and 3 molar equivalents or less. Further, taking capacity increase into consideration, it is preferably conductive polymer monomer: ionic liquid = 1: 0.1 to 2 (molar ratio), and if the ionic liquid is 0.1 or more, there is an effect on capacity improvement. It may begin to become noticeable, and the effect may become noticeable as the amount added increases. On the other hand, if the ratio is 1 or more, the deterioration of ESR characteristics may increase. Therefore, the ratio of the ionic liquid / conductive polymer monomer is preferably 0.1 or more from the viewpoint of capacity improvement, and preferably from the viewpoint of low ESR. 1 or less.

  The conductive polymer monomer used in the present invention is not particularly limited, but thiophene or a derivative thereof, pyrrole or a derivative thereof, since it has high conductivity at the time of polymer formation and is stable in the air. Aniline or a derivative thereof, quinone or a derivative thereof, quinoline or a derivative thereof, furan or a derivative thereof. These conductive polymer monomers may be used alone or in combination of two or more.

  Examples of thiophene derivatives include EDOT, 3-alkylthiophene (alkyl groups include butyl, hexyl, octyl, dodecyl, etc.), 3-fluorophenylthiophene, 3-arylthiophene, etc. It is not limited to.

Examples of pyrrole derivatives include, but are not limited to, those having a pyrrole skeleton and having substituents such as a hydroxyl group, a carboxyl group, and an alkyl group.
Examples of aniline derivatives include, but are not limited to, those having an aniline skeleton having an alkyl group, a cyano group, a sulfone group, or a carboxyl group.
Examples of the quinone derivative include, but are not limited to, benzoquinone having a substituent, naphthoquinone having a substituent, and anthraquinone having a substituent.

  In the present invention, a thiophene derivative and pyrrole are preferable, and in particular, EDOT or pyrrole is preferably used in terms of conductivity and heat resistance.

  In situ polymerization in the present invention refers to chemical polymerization and electrolytic polymerization.

  First, a method by chemical polymerization will be described. The chemical polymerization method is a method of polymerizing and synthesizing a conductive polymer monomer such as pyrrole in the presence of an appropriate oxidizing agent.

  Examples of the oxidizing agent used in the present invention include, for example, ferric paratoluenesulfonate, ferric naphthalenesulfonate, ferric n-butylnaphthalenesulfonate, ferric triisopropylnaphthalenesulfonate, persulfate, persulfate, Hydrogen oxide, diazonium salts, halogens and halides, or transition metal salts such as iron, copper and manganese can be used. The conductive polymer synthesized by chemical polymerization can obtain a polymer having conductivity in a one-step reaction by incorporating an anion of an oxidant into the polymer as a dopant in the polymerization process. It is preferable to use ferric paratoluenesulfonate containing paratoluenesulfonate ions having high mobility as an oxidizing agent.

  In the case of chemical polymerization, it is preferable to add an oxidizing agent to a solution containing a conductive polymer monomer and an ionic liquid. When chemical polymerization is performed in the presence of an ionic liquid, the liquid component is easily filled in the pores, and the capacity development rate is improved.

  The polymerization conditions for chemical polymerization may be known polymerization conditions, and the temperature range is -50 ° C to 200 ° C, particularly preferably 0 ° C to 180 ° C. The polymerization time is 1 minute to 24 hours, particularly preferably 1 minute to 5 hours. The polymerization may be repeated a plurality of times.

  Next, a method for performing in situ polymerization using a solution (A) containing a conductive polymer monomer by electrolytic polymerization will be described. The electrolytic polymerization method is a method in which a conductive polymer is dissolved in a solvent and anodized to dehydrogenate the conductive polymer. Electropolymerization is, for example, a method in which a pyrrole monomer is dissolved in a solvent together with a supporting electrolyte and subjected to dehydrogenation polymerization by anodic oxidation, whereby polypyrrole, which is a conductive polymer, can be deposited on the anode. Generally, since the oxidation-reduction potential of the polymer is lower than that of the monomer, the oxidation of the polymer skeleton proceeds further during the polymerization process, and accordingly, the anion of the supporting electrolyte is incorporated into the polymer as a dopant. In electropolymerization, such a mechanism has an advantage that a polymer having conductivity can be obtained without adding a dopant later. As the supporting electrolyte used in the present invention, ammonium salts, amine salts, quaternary ammonium salts, tertiary amines, organic acids, imidazolium salts, and the like are preferable.

  When the electropolymerization is performed in the presence of the ionic liquid, the polymer is formed in a state where the ionic liquid is introduced into the pores. Therefore, an improvement in capacity development rate can be expected as compared with the case where the ionic liquid is not included. Therefore, it is preferable to add an ionic liquid. When synthesizing a conductive polymer by electrolytic polymerization, the oxide film on the valve metal is a dielectric, so a conductive film is formed on the dielectric beforehand to make it conductive, Electropolymerization is performed by applying a voltage. As the conductive film used for such a purpose, a conductive polymer synthesized by chemical polymerization, pyrolytic manganese dioxide, or the like can be used.

  The polymerization solvent may be a known one and is not particularly limited. Examples include methanol, ethanol, butanol, diethylene glycol, 2-propanol, acetone, diethyl ether, ethyl acetate, THF, DMF, acetonitrile, DMSO, dimethyl carbonate, ethylene carbonate, propylene carbonate, hexane, toluene, chloroform, etc., ionic liquid From the viewpoint of compatibility with the conductive high monomer molecule, butanol is particularly preferable.

  Next, the step of impregnating the conductive polymer dispersion (B) to form an electrolyte will be described.

  The step (2a) is performed for in situ polymerization of the step (1a), smoothing of the electrolyte surface, and dense coating of the edge of the electrode.

  Examples of the material contained in the conductive polymer dispersion (B) include a conductive polymer (D), a dopant anion of the conductive polymer (D), a binder, a dispersion solvent, and an ionic liquid.

  The conductive polymer (D) is not particularly limited, but is preferably a product of at least one polymerization selected from the group consisting of thiophene, thiophene derivatives, pyrrole, pyrrole derivatives, aniline and aniline derivatives. . Among them, a polymer of a thiophene derivative is preferable from the viewpoint of stability and heat resistance, and PEDOT is most preferable as the conductive polymer. Here, as the derivative of thiophene, the derivative of pyrrole, and the derivative of aniline, the same ones as the conductive polymer monomer can be used.

  The dopant anion of the conductive polymer (D) is an indispensable material for securing conductivity as a counter anion of the conductive polymer (D). Polymeric anions and monomeric anions can be used, but from the viewpoint of heat resistance and electrical conductivity, polymeric anions are preferred, and among them, polymer carboxylic acid or polymer sulfonic acid anions are preferred, and polystyrene sulfonic acid (hereinafter referred to as PSS). Abbreviated) is most preferred.

  The binder is important for effectively bonding the electrolyte layer formed by in situ polymerization and the outer polymer layer. Preferred materials include organic binders such as polyvinyl alcohol, polyvinyl chloride, polyacrylic acid esters, polyacrylic amides and melamine compounds as crosslinking agents, functional silanes and polyurethanes as crosslinkable polymers, and polyacrylates. The amount of the binder in the conductive polymer dispersion (B) is preferably about several to 10% in consideration of adhesiveness.

  As the dispersion solvent, water or alcohols typified by methanol, ethanol and butanol, a mixture of water and these alcohols can be used, and a particularly preferred dispersion solvent is water.

  Step (2a) may be performed in the presence of an ionic liquid. For example, when an ionic liquid is included in the conductive polymer dispersion (B), the ionic liquid is more solid than the solid conductive polymer from the gap between the electrolyte layers formed by the in-situ polymerization in the previous step. Since it easily penetrates into the voids and element pores of the contained electrolyte, there is an advantage that the capacity is increased.

  The amount of the ionic liquid used is not particularly limited, but when many ionic liquids are added, ESR characteristics tend to deteriorate. Therefore, in the form in which the ionic liquid is added to the conductive polymer dispersion (B), the total amount of the ionic liquid added is 20 with respect to 100% by weight of the total amount of the conductive polymer dispersion (B) and the ionic liquid. The content is preferably not more than wt%, more preferably not less than 0.01 wt% and not more than 10 wt%. Furthermore, taking capacity increase into consideration, the amount of the ionic liquid in the conductive polymer dispersion (B) is preferably 0.05% by weight or more and 5% by weight or less of the conductive polymer dispersion (B). . When the amount of the ionic liquid is 0.05% by weight or more, the effect of improving the capacity starts to become remarkable, and the effect tends to become remarkable as the addition amount increases. On the other hand, if the content is 5% by weight or more, the deterioration of ESR characteristics tends to increase. Therefore, the weight of the ionic liquid with respect to the conductive polymer dispersion (B) is preferably 0.05% by weight or more from the viewpoint of capacity improvement. From the viewpoint of low ESR, it is preferably 5% by weight or less.

  This process can be applied to both chip-type and wound-type elements. As for the chip type, low ESR and low leakage current can be expected by covering the edge surface and smoothing the outer surface of the sintered body. On the other hand, for the wound type, in addition to the coating of the edge surface and the smoothing of the electrode surface, the filling of the polymer into the void generated by the cleaning becomes more prominent than the chip type, so in addition to the low ESR and low leakage current, High capacity can be expected.

  In the present invention, a cleaning step (1b) may be performed between step (1a) and step (2a). The washing step refers to a step of washing the electrolyte obtained by chemical polymerization and / or electrolytic polymerization with water and / or an organic solvent. Although washing | cleaning said here is not specifically limited, It is mentioned as a preferable method to immerse and stir in water and / or an organic solvent between room temperature and 80 degreeC for 1 minute-1 hour. Although it does not specifically limit as an organic solvent to be used, Alcohol type, ether type, nitrile type, ketone type, amide type, carbonate type, ester type, sulfur containing solvent, halogenated hydrocarbon and hydrocarbon type A solvent is mentioned, You may use 2 or more types of these solvents. From the viewpoint of the cleaning effect, an alcohol type is preferably used, and methanol, ethanol, and n-butanol are particularly preferable.

  In the washing step, the conductive polymer monomer and / or the oxidizing agent component and / or the ionic liquid incorporated into the conductive polymer by washing the electrolyte obtained in the polymerization step with water and / or an organic solvent. Can be eluted. This process can be expected to have the effect of removing iron salts that hinder low ESR characteristics, long life characteristics, and high breakdown voltage. The voids generated by the escape of these are filled by impregnation with the conductive polymer dispersion (B) in the next step (2a).

  Although this method can be applied to both chip-type and wound-type elements, it has a significant effect on wound-type elements that are not applied with cleaning in the conventional manufacturing method, because the effect on the improvement of characteristics is large. Have. An electrolyte layer may be further formed using the solution (A) containing the conductive polymer monomer again from the electrolyte obtained in this washing step.

  Next, the electrolyte forming method of the present invention will be described in more detail. The prior art in the following refers to a technique for forming an electrolyte using a solution containing neither an in situ polymerization solution (A) nor a conductive polymer dispersion (B) containing an ionic liquid.

  The first production method includes an embodiment in which the in situ polymerization solution (A) does not contain an ionic liquid and the conductive polymer dispersion (B) contains an ionic liquid. In the first production method, in-situ polymerization is not different from the prior art, but since the ionic liquid is contained in the conductive polymer dispersion (B), the electrolyte in the dispersion (B) is used. At the time of formation, the ionic liquid, which is a liquid, is more likely to enter the gap between the electrolyte layers formed by in situ polymerization than the conductive polymer that is a solid, and the capacity is improved as compared with the prior art.

  In the first production method, when a washing step is added after in situ polymerization, the insulator containing the iron salt is removed by washing, and voids are developed in the electrolyte. In the subsequent electrolyte formation with the conductive polymer dispersion (B), the conductive polymer and the ionic liquid are filled instead of the insulator. The ESR characteristic is improved by the filled conductive polymer. In addition, since the ionic liquid that is liquid is more likely to enter the voids and element pores that are solid than the conductive polymer that is solid, the capacity is improved as compared with the manufacturing method in which cleaning is performed in the prior art. Thus, in the first production method, it is more preferable to add a washing step.

  The second production method includes an embodiment in which the in situ polymerization solution (A) contains an ionic liquid and the conductive polymer dispersion (B) does not contain an ionic liquid. In the second production method, since the wettability with the electrode is improved by using a solution containing an ionic liquid in in situ polymerization, the polymerization solution is impregnated into the pores of the electrode surface. It is estimated that the improving effect will be manifested.

  In the second production method, when a washing step is added after in situ polymerization, the insulator containing the iron salt is removed by washing, and voids appear in the electrolyte. In the subsequent electrolyte formation with the conductive polymer dispersion (B), the conductive polymer is filled instead of the insulator, so that the ESR characteristics are improved. Thus, also in the second production method, it is more preferable to add a washing step.

  A third production method includes an embodiment in which the in situ polymerization solution (A) contains an ionic liquid and the conductive polymer dispersion (B) also contains an ionic liquid. In the third production method, it is estimated that the polymer solution is impregnated into the pores of the electrode surface because the wettability with the electrode is improved by using a solution containing an ionic liquid in in situ polymerization. In addition, the conductive polymer dispersion (B) also contains an ionic liquid, which is more liquid than the solid conductive polymer when the electrolyte is formed using the conductive polymer dispersion (B). Since a certain ionic liquid easily enters the gap between the electrolyte layers formed by in situ polymerization, the capacity is improved as compared with the prior art.

  In the third production method, when a washing step is added after in situ polymerization, the insulator containing the iron salt is removed by washing, and voids appear in the electrolyte layer. In the subsequent electrolyte formation with the conductive polymer dispersion (B), the conductive polymer and the ionic liquid are filled instead of the insulator. The ESR characteristic is improved by the filled conductive polymer. In addition, since the ionic liquid that is liquid is more likely to enter the voids and element pores that are solid than the conductive polymer that is solid, the capacity is improved as compared with the manufacturing method in which cleaning is performed in the prior art.

  Regarding the third production method, since the ionic liquid is contained in both the in situ polymerization solution (A) and the conductive polymer dispersion (B), the ionic liquid flowed out excessively in the washing after the in situ polymerization. Even in the case, when the subsequent conductive polymer dispersion (B) is used, it can be filled with an ionic liquid, and in terms of improving the capacity expression rate compared to the first and second production methods. This is preferable because a stable effect is expected. However, if the amount of the ionic liquid is too large, there is a risk of increasing the ESR, and it is necessary to pay attention to the formulation as described above.

  A conductive polymer aluminum electrolytic capacitor to which an electrolyte produced by the forming method of the present invention is applied is formed using an electrolyte layer provided with a high ion conductivity region, and sandwiches the electrolyte layer and the electrolyte layer. And at least an anode and a cathode arranged to face each other. The electrolyte of the present invention can be formed in a wound type or laminated type conductive polymer aluminum electrolytic capacitor. A wound-type conductive polymer aluminum electrolytic capacitor typically has a configuration in which a conductive polymer as an electrolyte is filled in an element having a surface on which a dielectric film is formed, an anode, a separator, and a cathode. is there. On the other hand, in a laminated type conductive polymer aluminum electrolytic capacitor, an anode filled with an electrolyte is deposited on the anode surface on which a dielectric film is formed, for example, a graphite layer and a silver paste layer are stacked in this order, and the cathode is drawn from the silver paste layer. Structure.

  As the anode of the conductive polymer aluminum electrolytic capacitor of the present invention, conventionally known conductive polymer capacitors can be preferably used. For example, as the anode metal, etching is performed on the surface of the aluminum electrode foil to form etching holes. By using a combination of the above and a dielectric film made of an oxide film formed by a method such as anodic oxidation on the surface of the anode metal, an anode made of an anode metal and a dielectric film can be formed. The above anodic oxidation can be performed by immersing the anode metal in an aqueous solution of ammonium adipate, for example, and applying a chemical voltage.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is a result obtained by simulating a wound capacitor, but the present invention is not limited to these examples at all. Changes can be made as appropriate without changing the range.

  (Ionic liquid) A method for synthesizing or obtaining ionic liquids and salts will be described below.

  [Emim] [AcO] (1-ethyl-3-methylimidazolium acetate, manufactured by Aldrich)

  [Emim] [LA] (1-ethyl-3-methylimidazolium lactate, manufactured by Aldrich)

  [Emim] [MA] (1-ethyl-3-methylimidazolium mandelate)

1-Ethyl-3-methylimidazolium hydrogen carbonate 50% aqueous solution (6000 mg, 17.42 mmol) was cooled to 0 ° C. Thereafter, an aqueous solution of mandelic acid (2615 mg, 17.42 mmol) was slowly added dropwise and stirred at room temperature for 1 hour. The reaction solution was concentrated as it was, the solvent was distilled off under reduced pressure, dichloromethane was added to the resulting residue, and the organic layer was dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure to obtain 4560 mg of the target compound as a light brown oil. (Yield 100%)
1H NMR (CDCl ₃ , 300 MHz) δ 1.38 (t, 3H), 3.81 (s, 3H), 4.16 (q, 2H), 4.39 (s, 1H), 7.11-7. 22 (m, 2H), 7.33-7.36 (m, 3H), 7.69 (s, 1H), 7.77 (s, 1H), 9.24 (s, 1H)
[Bmim] [TFA] (1-butyl-3-methylimidazolium trifluoroacetate, manufactured by Merck & Co., Inc.)

  [Bmim] [CA] (1-butyl-3-methylimidazolium caprylate)

1-butyl-3-methylimidazolium hydrogen carbonate 50% aqueous solution (5.00 g, 12.48 mmol) was cooled to 0 ° C. Thereafter, an aqueous solution of caprylic acid (1.80 g, 12.48 mmol) was slowly added dropwise and stirred at room temperature for 1 hour. The reaction solution was concentrated as it was, the solvent was distilled off under reduced pressure, dichloromethane was added to the resulting residue, and the organic layer was dried over anhydrous sodium sulfate. The solvent was distilled off under reduced pressure to obtain 2.20 g of the target compound as a yellow oil. (Yield 62%)
1H NMR (CDCl ₃ , 300 MHz) δ 0.83-0.92 (m, 7H), 1.21-1.29 (m, 11H), 1.38 (m, 2H), 1.73-1.78 (M, 2H), 3.85 (s, 3H), 4.17 (t, 2H), 7.72 (s, 1H), 7.79 (s, 1H), 9.39 (s, 1H)
[Bmim] [PA] (1-butyl-3-methylimidazolium phenylacetate)

Amberlite IRA400 (OH) (140 mL) was added to the chromatographic column tube, 1N NaOH aqueous solution (2.5 L) was poured to activate the Amberlite IRA400 (OH), and then purified water (1.5 L) until the filtrate became neutral. ). After adding pure water (50 mL) to 1-butyl-3-methylimidazolium chloride (5.0 g, 28.63 mmol) and dissolving it, this was passed through the previously activated Amberlite IRA400 (OH) to give 1-butyl An aqueous solution of -3-methylimidazolium hydroxide was obtained. After adding pure water (200 mL) and THF (100 mL) to phenylacetic acid (3.9 g, 28.63 mmol) to make a homogeneous solution, 1-butyl-3-methylimidazolium hydroxide aqueous solution was slowly added dropwise thereto. Stir at 0 ° C. for 12 hours. The reaction solution was concentrated as it was, acetonitrile (90 mL) and methanol (10 mL) were added to the obtained residue, and the mixture was stirred at 0 ° C. for 30 min. The filtrate was concentrated and heated under reduced pressure to obtain 8.0 g of the target compound as a pale yellow oil. (Yield 100%)
1H NMR (DMSO-d ₆ , 300 MHz) δ 0.89 (t, 3H), 1.21-1.28 (m, 2H), 1.70-1.77 (m, 2H), 3.23 (s 2H), 3.83 (s, 3H), 4.15 (t, 2H), 7.09-7.19 (m, 5H), 7.70 (s, 1H), 7.77 (s, 1H), 9.29 (s, 1H)

<Capacity measurement method>
The capacity was measured using the mercury cell shown in FIG. As a device, an LCR meter 3522-50 manufactured by Hioki Electric Co., Ltd. was used, and a capacity value of 120 Hz was used as data.

<ESR measurement method>
After the initial capacity measurement, ESR was measured using the mercury cell shown in FIG. Using an LCR meter 3522-50 manufactured by Hioki Electric Co., Ltd., an ESR value of 100 kHz was used as data.

<Leakage current measurement method>
After the ESR measurement, the voltage was raised to 19 V under the condition of 100 mV / sec in an atmosphere at 105 ° C., and then held at 19 V for 1 hour. Subsequently, in a room temperature atmosphere, the current value after 2 minutes after the voltage was raised to 16 V under the condition of 100 mV / sec was measured, and the data was defined as leakage current.

Example 1
A conductive polymer electrolyte obtained by chemical polymerization of a solution (A) containing an EDOT (HC Starck-V TECH) monomer is formed on an aluminum oxide film, and after washing, a conductive polymer electrolyte containing an ionic liquid is formed. The conductive polymer aluminum electrolytic capacitor was produced by immersing it in the conductive polymer dispersion (B).

  That is, an aluminum etched foil having an effective area of 10 mm × 10 mm is dipped in a 1% ammonium adipate aqueous solution, first raised from 0 to 45 V at a rate of 20 mV / sec, and then a constant voltage of 45 V is applied for 40 minutes, A dielectric film was formed on the surface of the aluminum etched foil. Next, the aluminum etched foil on which the dielectric film was formed was washed with running deionized water for 3 minutes and then dried at 120 ° C. for 1 hour. The in-liquid capacity of the aluminum etched foil obtained at this time was 25 μF. The monomer composition used for forming the electrolyte was prepared by using 0.3 g of EDOT in a dried glass container, blending EDOT and ionic liquid [bmim] [AcO] so that the molar ratio = 1: 0.3, and stirring for 10 minutes. And adjusted. Next, a 40 wt% 1-butanol solution of iron paratoluenesulfonate is used as an oxidizing agent, and the amount of iron paratoluenesulfonate is 2 molar equivalents relative to EDOT in the monomer composition composed of EDOT / [emim] [AcO]. Was added to prepare a chemical polymerization solution.

  Next, the aluminum etched foil obtained was immersed in the chemical polymerization solution, and after being pulled up, heated at 120 ° C. for 1 hour to form an electrolyte on the surface of the foil.

  Next, 90 parts by weight of aqueous poly 3,4-ethylenedioxythiophene polystyrene sulfonic acid (PEDOT / PSS) dispersion (Sigma-Aldrich high conductivity coating type dispersion concentration 1.3 to 1.7% by weight), [ emim] [AcO], immersed in an aqueous conductive polymer dispersion composed of 2 parts by weight, 4 parts by weight of DMSO, and 4 parts by weight of polyvinyl alcohol, and dried at 80 ° C. for 15 minutes. The electrolyte was formed by immersing and drying in this aqueous conductive polymer dispersion three times.

  Thereafter, carbon paste “Everyom T-30PLB” manufactured by Nippon Graphite Trading Co., Ltd. was applied and dried at 150 ° C. for 30 minutes, then silver paste “4922N” manufactured by DuPont was applied and dried at 150 ° C. for 30 minutes, and the cathode was coated with copper foil. The lead was taken out to produce a conductive polymer aluminum electrolytic capacitor.

Using the conductive polymer aluminum electrolytic capacitor thus obtained, the capacity, ESR and leakage current were measured. The results are shown in Table 1. The capacity expression rate was converted by normalizing the capacitor capacity with respect to the liquid capacity. The results are average values of 10 electrodes. The results are shown in Table 1.
(Example 2)
A conductive polymer aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the ionic liquid was not contained in the chemical polymerization solution (A). The results are shown in Table 1.
(Example 3)
A conductive polymer aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the ionic liquid was not contained in the conductive polymer dispersion (B). The results are shown in Table 1.
(Examples 4, 7, and 10)
Except for changing the ionic liquid in the dispersion (B) to the ionic liquid shown in Table 1 and further by adding a washing step of 60 minutes immersion in methanol after in situ polymerization and heat treatment at 120 ° C. for 1 hour, A conductive polymer aluminum electrolytic capacitor was produced in the same manner as in Example 1. The results are shown in Table 1.

(Examples 5, 8, 11, 13 to 15)
The ionic liquid in the conductive polymer dispersion (B) is changed to the ionic liquid shown in Table 1, and after the in situ polymerization, it is immersed in methanol for 60 minutes, and a washing process is performed in which heat treatment is performed at 120 ° C. for 1 hour. A conductive polymer aluminum electrolytic capacitor was produced in the same manner as in Example 2 except that. The results are shown in Table 1.

(Examples 6, 9, and 12)
Except for changing the ionic liquid in the chemical polymerization solution (A) to the ionic liquid shown in Table 1 and adding a washing step of dipping in methanol for 10 minutes after in-situ polymerization and heating at 120 ° C. for 1 hour. A conductive polymer aluminum electrolytic capacitor was produced in the same manner as in Example 3. The results are shown in Table 1.

(Comparative Example 1)
A conductive polymer aluminum electrolytic capacitor was produced in the same manner as in Example 3 except that the ionic liquid in the chemical polymerization solution (A) was not used. The results are shown in Table 1.

(Comparative Example 2)
A conductive polymer aluminum electrolytic capacitor was produced in the same manner as in Example 6 except that the ionic liquid in the chemical polymerization solution (A) was not used. The results are shown in Table 1.

Claims (8)

Including the following steps (1a) and (2a),
A method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor, wherein the step (1a) and / or the step (2a) are performed in the presence of an ionic liquid.
(1a) a step of in situ polymerization of a conductive polymer monomer;
(2a) A step of impregnating the conductive polymer dispersion (B) after the step (1a). 2. The method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor according to claim 1, further comprising (1b) a step of performing cleaning between the steps (1a) and (2a).   The method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor according to claim 1 or 2, wherein the in situ polymerization is chemical polymerization and / or electrolytic polymerization.   The conductive polymer according to claim 1, wherein the conductive polymer monomer is at least one selected from the group consisting of thiophene, thiophene derivatives, pyrrole, pyrrole derivatives, aniline and aniline derivatives. A method for forming an electrolyte for an aluminum electrolytic capacitor.   The conductive polymer (D) contained in the conductive polymer dispersion (B) is produced by at least one kind of polymerization selected from the group consisting of thiophene, thiophene derivatives, pyrrole, pyrrole derivatives, aniline and aniline derivatives. The formation method of the electrolyte for electroconductive polymer aluminum electrolytic capacitors in any one of Claims 1-4 which is a thing.   The method for forming an electrolyte for a conductive polymer aluminum electrolytic capacitor according to claim 1, wherein the anion component of the ionic liquid is a carboxylate anion.   The cation component of the ionic liquid is ammonium ion, imidazolium ion, pyridinium ion, pyrrolidinium ion, pyrrolium ion, pyrazinium ion, pyrimidinium ion, triazonium ion, triazinium ion, triazine ion, quinolinium ion At least selected from the group consisting of isoquinolinium ion, indolinium ion, quinoxalinium ion, piperazinium ion, oxazolinium ion, thiazolinium ion, morpholinium ion, piperazine ion and derivatives thereof The formation method of the electrolyte for electroconductive polymer aluminum electrolytic capacitors in any one of Claims 1-6 which is 1 type.   The manufacturing method of the electroconductive polymer aluminum electrolytic capacitor containing the formation method of the electrolyte for electroconductive polymer aluminum electrolytic capacitors in any one of Claims 1-7.