JP5321964B2 - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a solid electrolyte obtained by forming a solid electrolyte containing a conductive polymer in a capacitor element formed by winding or laminating an anode electrode layer having an oxide film and a cathode electrode layer with a separator interposed therebetween. It relates to an electrolytic capacitor.

  A solid electrolytic capacitor including a solid electrolyte is hardly an aluminum electrolytic capacitor including a liquid electrolyte (electrolytic solution), and there is almost no leakage of electrolyte or transpiration (so-called dry-up). Since it is easy to reduce ESR, it has been widely used in recent years.

  Solid electrolytic capacitors include a sintered pellet type using a powdered valve action metal powder such as tantalum or aluminum, and a foil type using a valve action metal foil. For example, in a foil-type solid electrolytic capacitor, an aluminum foil in which an anodic oxide film as a dielectric is formed on an etched anode electrode foil is generally used. When the anode electrode foil is an aluminum foil, an etched aluminum foil or an aluminum alloy foil is used as the cathode electrode foil in the same manner as the anode electrode foil.

  In manufacturing the lead electrode foil and the cathode electrode foil, a lead terminal is attached to each of the anode electrode foil and the cathode electrode foil by welding or welding, and the anode electrode foil and the cathode electrode foil are spirally wound through a separator. Turn to make a capacitor element (winding type).

  In the case of a laminated type, a capacitor element is produced by laminating several layers with a separator interposed between an anode electrode foil and a cathode electrode foil. Or a solid electrolyte is apply | coated on an anode electrode layer, carbon and silver paste are apply | coated, and it is laminated | stacked in several layers as a cathode electrode layer, and produces a capacitor | condenser element.

  Next, in the case of a wound type, a capacitor element is impregnated with a predetermined monomer (for example, thiophene monomer) and an oxidizing agent, and this is polymerized to form a solid electrolyte containing a conductive polymer. Thereafter, the capacitor element is housed in a bottomed cylindrical aluminum case, and the case opening is sealed with a sealing member such as a sealing rubber.

  In the case of laminated type, a solid electrolyte is formed with a predetermined monomer on a capacitor element laminated in several layers with a separator sandwiched between an anode electrode foil and a cathode electrode foil, an external terminal is attached, and on the anode electrode foil In general, a solid electrolyte is formed by coating or impregnation, carbon and silver paste are applied, and a plurality of or one internal element is formed, and external terminals are attached and external resin molding is performed. It is.

  By the way, in an electrolytic capacitor having a general configuration, the valve metal layer is usually roughened and widened to increase the capacity, and the surface thereof has a fine uneven shape. Therefore, the oxide film layer formed on the valve action metal layer also has a fine uneven shape. The oxide film layer is a natural deterioration, rapid temperature change, electrical shock (overvoltage, reverse voltage, or excessive ripple current applied), physical shock that occurs when an electrolytic capacitor is left unloaded for a long period of time. Due to factors such as the addition of, there is a risk of significant damage leading to loss of the function. When such damage occurs, the electrolytic capacitor causes a phenomenon such as an increase in leakage current and a short circuit. Therefore, in order to prevent the occurrence of such a short circuit, it is desirable that the electrolytic capacitor has a function (self-healing function) of repairing a damaged portion of the oxide film layer by itself.

  In the above-described aluminum electrolytic capacitor, the valve metal exposed at the damaged portion comes into contact with the electrolytic solution. This electrolytic solution contains ionic molecules or compounds, and when a predetermined rated voltage is applied to the electrolytic capacitor, the valve action metal is oxidized by oxygen generated from the ionic molecules or compounds, and the oxide film The damaged part of the layer is repaired. On the other hand, the solid electrolytic capacitor has essentially no self-repairing function as described above because the electrolyte has substantially no ionic conductivity. However, the functional polymer itself has an insulating property and has a property of interrupting the current flowing through the defective portion of the dielectric. However, since the basic repair of the damaged portion of the oxide film is not performed, the withstand voltage of the product has to be lower than that of the aluminum electrolytic capacitor using the same anodizing voltage, and the rated voltage such as 50V or 63V is required. There was a problem that it was difficult to make a solid electrolytic capacitor having a high height.

  In recent years, poly (3,4-ethylenedioxythiophene) has attracted attention as a conductive polymer constituting a solid electrolyte (hereinafter, “3,4-ethylenedioxythiophene” is referred to as “3,4-EDT”). Also, “poly (3,4-ethylenedioxythiophene)” is also referred to as “3,4-PEDT”). In the solid electrolyte containing 3,4-PEDT, the withstand voltage is not sufficient, and further improvement of the withstand voltage is required at present. Here, the following Non-Patent Document 1 describes many methods for synthesizing 3,4-PEDT and derivatives thereof, and raw material monomers, and further application examples thereof. However, the raw material monomers described in this document, and further, application examples of 3,4-PEDT are merely examples, and the contents described in this document are specifically improvements in various physical properties of solid electrolytic capacitors, in particular solids. It is not intended to improve the withstand voltage of electrolytic capacitors.

  Further, Patent Document 1 below describes a solid electrolytic capacitor including a solid electrolyte containing polythiophene having 3,4-ethyleneoxythiathiophene as an essential repeating unit. However, such a solid electrolytic capacitor has been developed for the purpose of reducing leakage current, and cannot withstand withstand voltage.

JP-A-2005-39276

L. Groendaal, F.M. Jonas, D.M. Freitag, H.C. Pieartzik and J.M. R. Reynolds, Adv. Mater. 12 (2000) 481-494

  This invention is made | formed in view of the said situation, The objective is to improve the withstand voltage in a solid electrolytic capacitor provided with the solid electrolyte containing a conductive polymer.

The above object can be achieved by the present invention as described below. That is, the solid electrolytic capacitor according to the present invention is a solid containing a conductive polymer in a capacitor element formed by winding or laminating an anode electrode layer having an oxide film and a cathode electrode layer with a separator interposed therebetween. In the solid electrolytic capacitor formed with an electrolyte, the conductive polymer has the following formula (I):

(Wherein R is a hydrocarbon group having 1 to 10 carbon atoms), and is a polymer of a monomer containing a monomer (hereinafter also referred to as “side chain-containing 3,4-EDT”). To do.

  Since the solid electrolyte is composed of a polymer of a monomer containing side chain-containing 3,4-EDT, the solid electrolytic capacitor includes a solid electrolyte composed of a polymer of 3,4-EDT alone. Compared with the capacitor, the withstand voltage is greatly improved.

In the solid electrolytic capacitor, the conductive polymer has the following formula (I):

(Wherein R is a hydrocarbon group having 1 to 10 carbon atoms) It is preferable that the capacitor element is impregnated with a monomer containing a monomer and an oxidant and then polymerized. According to such a configuration, the generation capacity of the side chain-containing 3,4-PEDT is increased by including the polymer of the monomer containing the side chain-containing 3,4-EDT in the capacitor element. -Since the production rate of PEDT per volume is reduced as compared with PEDT, the capacitance is slightly reduced and the ESR is slightly increased, but the withstand voltage of the capacitor is further improved.

  In the solid electrolytic capacitor, R is more preferably a hydrocarbon group having 1 to 3 carbon atoms. According to this configuration, the withstand voltage can be improved while appropriately suppressing the decrease in the capacitance of the solid electrolytic capacitor and the increase in ESR.

  In the solid electrolytic capacitor, it is preferable that the anode electrode layer is an anode electrode foil and the cathode electrode layer is a cathode electrode foil.

In the solid electrolytic capacitor, the following formula (I):

(Wherein R is a hydrocarbon group having 1 to 10 carbon atoms), a carbon layer and a silver paste layer are sequentially formed as the cathode electrode layer, and the anode electrode layer It is preferable to laminate a plurality of sheets.

The method for producing a solid electrolytic capacitor according to the present invention includes a solid electrolyte containing a conductive polymer in a capacitor element in which an anode electrode layer having an oxide film and a cathode electrode layer are wound or laminated with a separator interposed therebetween. In the method for producing a solid electrolytic capacitor formed by forming the following formula (I):

(Wherein R is a hydrocarbon group having 1 to 10 carbon atoms) an impregnation step of impregnating a capacitor element with a monomer containing a monomer represented by a monomer and an oxidizing agent; And a polymerization step for forming the solid electrolyte containing the conductive polymer.

In the method for producing a solid electrolytic capacitor, the following formula (I):

(Wherein R is a hydrocarbon group having 1 to 10 carbon atoms), a carbon layer and a silver paste layer are sequentially formed as the cathode electrode layer, and the anode electrode layer It is preferable to laminate a plurality of sheets.

The typical exploded perspective view showing the capacitor element of the solid electrolytic capacitor concerning the present invention The typical perspective view which shows the assembly process which concerns on this invention The flowchart which shows the manufacturing process which concerns on this invention

  A solid electrolytic capacitor according to the present invention includes a solid electrolyte containing a conductive polymer in a capacitor element formed by winding or laminating an anode electrode layer having an oxide film and a cathode electrode layer with a separator interposed therebetween. Formed. Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic exploded perspective view showing a capacitor element of a solid electrolytic capacitor according to the present invention, and FIG. 2 is a schematic perspective view showing an assembly process according to the present invention. FIG. 3 is a flowchart showing the manufacturing process according to the present invention.

  As shown in FIG. 1, the capacitor element 10 according to the present embodiment is a foil wound type, and includes an anode electrode foil 11 as an anode electrode layer having an oxide film, and a cathode electrode foil 12 as a cathode electrode layer. It is manufactured by winding the separators 13 and 13 between them in a spiral shape. In the present invention, as the anode electrode layer and the cathode electrode layer having an oxide film, those obtained by sintering a powder of a valve action metal such as tantalum or aluminum may be used. In the present invention, the separators 13 and 13 may be carbonized by applying heat of, for example, 200 ° C. or higher after the capacitor element 10 is manufactured.

  In the present invention, a metal foil having a valve action such as tantalum or aluminum can be used for the anode electrode foil 11 and the cathode electrode foil 12, but in this embodiment, the anode electrode foil 11 and the cathode electrode foil 12 are used. In both cases, an example in which aluminum is used will be described.

  As the anode electrode foil 11, an aluminum foil is used in which the surface is roughened by an etching process, and then an oxide film 11a (not shown) as a dielectric is formed by, for example, an anodic oxidation method. On the other hand, the cathode electrode foil 12 is an aluminum foil or an alloy foil whose surface is roughened by etching, or an oxide film formed on the aluminum foil or an alloy foil thereof, or a valve metal foil or an alloy foil thereof in plain form. Alternatively, a material obtained by etching and attaching particles such as carbon or titanium to the surface by vapor deposition can be used.

  Prior to winding, lead terminals 14 are attached to the anode electrode foil 11 and the cathode electrode foil 12, respectively. The lead terminal 14 has a terminal body pressed into one end of a round bar wire made of aluminum and a CP wire (tin or solder) at the end of the round bar wire remaining on the other end side of the terminal body. Plating copper-coated steel wire) or lead terminals welded with tin or solder-plated copper wire can be used.

  For the attachment of the lead terminal 14 to the anode electrode foil 11 and the cathode electrode foil 12, for example, caulking, laser welding, or cold welding can be employed.

In the present invention, the solid electrolyte containing the conductive polymer is formed in the capacitor element 10 described above, in particular, between the anode electrode layer and the cathode electrode layer. The conductive polymer has the following formula (I):

(Wherein R is a hydrocarbon group having 1 to 10 carbon atoms) and is composed of a monomer polymer containing a monomer (side chain-containing 3,4-EDT). Here, R is a hydrocarbon group having 1 to 10 carbon atoms, specifically, a linear hydrocarbon group having 1 to 10 carbon atoms, a branched hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon. It is a group.

  Examples of the linear hydrocarbon group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Examples of the branched hydrocarbon group having 1 to 10 carbon atoms include isopropyl group, isobutyl group and t-butyl group. Examples of the alicyclic hydrocarbon group having 1 to 10 carbon atoms include a cyclohexyl group. Examples of the aromatic hydrocarbon group having 1 to 10 carbon atoms include a phenyl group and a benzyl group. In addition, this invention is not limited by these illustrations.

  When the present inventors diligently investigated the relationship between the type of hydrocarbon group R in the side chain-containing 3,4-EDT and each physical property of the solid electrolytic capacitor, the following points were found. That is, as the result of the Example mentioned later shows, it is comprised with the polymer of the side chain containing 3, 4-EDT compared with the solid electrolytic capacitor provided with the solid electrolyte comprised with the polymer of 3, 4-EDT single. In a solid electrolytic capacitor having a solid electrolyte, the withstand voltage is improved, and further, as the number of carbons in the hydrocarbon group R is increased, the withstand voltage of the solid electrolytic capacitor is improved while the capacitance is decreased. In addition, the present inventors have found a tendency for ESR to rise. Therefore, as a solid electrolytic capacitor, in the present invention, when the main purpose is to improve the withstand voltage, or the main purpose is to improve the capacitance and reduce the ESR while improving the withstand voltage to some extent, Any number of carbon atoms can be selected as the number of carbon atoms in the hydrocarbon group R of 3,4-EDT. However, in the present invention, the carbon number in the hydrocarbon group R is 1 to 3 in order to improve the withstand voltage while appropriately suppressing the decrease in the capacitance of the solid electrolytic capacitor and the increase in ESR. It is preferable.

  In order to improve the withstand voltage, the content of the side chain-containing 3,4-EDT in all monomers for forming the conductive polymer is 5% by weight (hereinafter referred to as “wt%”). Or more), more preferably 50 wt% or more, and particularly preferably 100 wt%. In the case of suppressing an increase in ESR due to an increase in breakdown voltage, the concentration can be arbitrarily changed to 100 wt% or less. On the other hand, if it is 5 wt% or less, it is difficult to achieve the effect, the effect of improving the breakdown voltage cannot be obtained, and the ESR increases. When it is 50 wt% or more, the withstand voltage is further improved, which is preferable. 100 wt% is particularly preferable because the pressure resistance is further improved and the monomer is not mixed. The monomer that can be used in addition to the side chain-containing 3,4-EDT is not particularly limited as long as it is a monomer copolymerizable with the side chain-containing 3,4-EDT. , 4-EDT and the like. Moreover, in this invention, only 1 type may be used for side chain containing 3, 4-EDT, and 2 or more types may be mixed and used for it. When mixing two or more types, the mixing ratio is arbitrarily changed when the main purpose is to improve the withstand voltage, or when the main purpose is to improve capacitance and reduce ESR. Is possible.

The monomer containing the side chain-containing 3,4-EDT described above is polymerized by oxidative polymerization using an oxidant to form a conductive polymer. Examples of the oxidizing agent include an aqueous oxidizing agent and an organic solvent oxidizing agent. Examples of aqueous oxidizing agents include peroxodisulfuric acid and its Na salt, K salt, NH ₄ salt, cerium (IV) nitrate, cerium (IV) ammonium nitrate, iron (III) sulfate, iron (III) nitrate, iron chloride (III) and the like can be used.

  As the organic solvent-based oxidizing agent, ferric salts of organic sulfonic acids such as iron (III) dodecylbenzenesulfonate and iron (III) p-toluenesulfonate can be used. It is not limited.

  In the present invention, when the capacitor element 10 is impregnated with the monomer containing the side chain-containing 3,4-EDT and the oxidizing agent, the capacitor element 10 may be diluted with a solvent to facilitate the impregnation. As the solvent, those which are inactive in the polymerization process of the monomer containing the side chain-containing 3,4-EDT can be used, for example, ethers such as tetrahydrofuran (THF), dioxane, diethyl ether; acetone, methyl ethyl ketone, etc. Ketones; aprotic solvents such as dimethylformamide, acetonitrile, benzonitrile, N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO); alcohols such as methanol, propanol, butanol; or water, or a mixed system thereof Can be used. Water, alcohols or ketones, or a mixed system thereof is preferable.

  In the solid electrolytic capacitor according to the present embodiment, the capacitor element 10 on which the solid electrolyte is formed has a bottomed cylindrical aluminum with a sealing rubber 17 attached to the lead terminals 14 and 14 side as shown in FIG. The outer casing 18 is housed in the outer casing 18 and is formed by forming a lateral throttle groove in the peripheral wall on the opening side of the outer casing 18 and curling the edge of the opening.

  Next, a method of manufacturing a solid electrolytic capacitor having the capacitor element 10 will be described along the flowchart of FIG.

  First, in the element winding process, the anode electrode foil 11 is cut out to a predetermined width from a wide aluminum foil having a surface roughened by an etching process and formed with an anodized film by, for example, an anodic oxidation method. Similarly, the cathode electrode foil 12 is cut out as a predetermined width from a wide aluminum foil whose surface is roughened by an etching process. Then, after attaching the lead terminals 14 and 14 to the anode electrode foil 11 and the cathode electrode foil 12, respectively, while sandwiching the separators 13 and 13 between the anode electrode foil 11 and the cathode electrode foil 12, each electrode foil 11, The capacitor element 10 is obtained by winding 12 in a spiral shape.

  Next, a plurality of capacitor elements 10 are welded to the hoop material (not shown) of the CP wires of the lead terminals 14 and 14 of each capacitor element 10 (hoop welding), and then repair formation is performed. With this repair conversion, a chemical conversion film is formed on the cut surfaces of the electrode foils 11 and 12 cut out from the wide aluminum foil, and a defective portion of the oxide film generated when the lead terminals 14 are attached is repaired.

  Restoration conversion is performed by immersing the capacitor element 10 in a conversion liquid mainly composed of ammonium adipate for 20 to 60 minutes, for example, and applying a predetermined voltage. Thereafter, preferably, the capacitor element 10 is carbonized by applying heat at 200 ° C. or higher at which the separator is carbonized, and then immersed in a chemical conversion liquid containing ammonium phosphate as a main component for 5 to 20 minutes, for example. Do.

  Next, the capacitor element 10 is impregnated with the monomer containing the side chain-containing 3,4-EDT and the oxidizing agent (impregnation step). The impregnation ratio of the monomer and the oxidizing agent is preferably, for example, a molar ratio, and the oxidizing agent is about 1-2 with respect to the monomer 1. As described above, when the capacitor element 10 is impregnated with the monomer containing the side chain-containing 3,4-EDT and the oxidizing agent, the capacitor element 10 may be diluted with a solvent in order to facilitate the impregnation. The amount of the dilution solvent used with respect to the total amount of the monomer and the oxidizing agent is preferably about 0.5 to 5 with respect to the total amount 1 of the monomer and the oxidizing agent, for example, in a weight ratio. After this impregnation step, the capacitor element 10 is heated to form a solid electrolyte containing a conductive polymer (polymerization step). The heating temperature and heating time of the capacitor element 10 in this polymerization step are not particularly limited as long as the monomer containing the side chain-containing 3,4-EDT is appropriately polymerized. For example, the heating temperature is 30 to 200 ° C. The heating time is 30 minutes to 8 hours.

  As an assembly process, as shown in FIG. 2, the capacitor element 10 with the sealing rubber 17 attached to the lead terminals 14, 14 side is housed in a bottomed cylindrical aluminum outer case 18, and the outer case 18 A lateral throttle groove is formed on the peripheral wall on the opening side, and the edge of the opening is curled. After assembly, aging and processing such as lead terminals are performed.

  Examples (Examples 1 to 5) and Comparative Examples (Comparative Example 1) that specifically show the configuration and effects of the present invention will be described below. In addition, about each evaluation (electrostatic capacity, ESR, and withstand voltage), it shows by the index when the conventional product (Comparative Example 1) is set to 100, and the larger the numerical value, the better the electrostatic capacity and withstand voltage, For ESR, the smaller the value, the better.

Example 1
After a rough aluminum foil having a thickness of 100 μm was roughened by etching, a chemical conversion voltage of 130 V was applied to form an oxide film by anodic oxidation to obtain a chemical conversion foil. This chemical conversion foil was cut into a width of 4 mm to obtain an anode foil. Next, the surface of a wide aluminum foil having a thickness of 50 μm was roughened by etching, and then cut into a width of 4 mm to obtain a cathode foil. A lead terminal was connected to each electrode foil by a caulking method, and was wound while facing each other through a separator to manufacture a capacitor element. Thereafter, the capacitor element was immersed in an aqueous solution of ammonium adipate at 60 ° C., and restoration formation was performed at an anode electrode formation voltage of 130V.

  Next, the capacitor element is impregnated with a monomer in which the R part of the side chain-containing 3,4-EDT is a methyl group and a mixed solution in which butanol is added to p-toluenesulfonic acid ferric acid as an oxidizing agent ( Impregnation step), left in an atmosphere at 100 ° C. for 60 minutes to form a side chain-containing 3,4-PEDT, which is a conductive polymer, between the anode electrode foil and the cathode electrode foil. After that, the capacitor element is housed together with the sealing rubber in an outer case made of a cylindrical aluminum material with a bottom, a lateral throttle groove is formed on the outer peripheral wall of the opening of the outer case, and the edge of the opening is curled and sealed did. Finally, the CP wire of each lead terminal is inserted into a seat plate for surface mounting, then the CP wire is rolled, and further the CP wire is bent along the seat plate surface, so that a surface mount type solid electrolytic capacitor Manufactured. Thereafter, the capacitance value at 120 Hz, the equivalent series resistance (ESR) at 100 KHz, and the withstand voltage swept at 0.1 mV / sec were measured. The results are shown in Table 1.

Examples 2-3
The side chain-containing 3,4-EDT was prepared in the same manner as in Example 1 except that R was an ethyl group (Example 2) and R was a propyl group (Example 3). In Examples 1 to 3, the content of the side chain-containing 3,4-EDT is 100 wt%.

Comparative Example 1
Instead of the side chain-containing 3,4-EDT in which the R part is a methyl group, it was prepared in the same manner as in Example 1 except that it was 3,4-EDT containing no side chain.

  For Comparative Example 1 and Examples 1 to 3, the capacitance value at 120 Hz, the equivalent series resistance (ESR) at 100 KHz, and the withstand voltage swept at 0.1 mV / sec were measured. Table 1 shows the comparison results of Examples 1 to 3 when Comparative Example 1 is 100. In addition, about a capacitance value and a withstand voltage, it shows that it is so favorable that a numerical value is large, and shows that it is so favorable that a numerical value is small.

Example 1a to Example 3a
Example 1a is the same as Example 1 except that a monomer in which 5 wt% of the monomer having an R part of the side chain-containing EDT is a methyl group and 95 wt% of a 3,4-EDT monomer having no side chain is used. Produced. Example 2a is the same as Example 1 except that a monomer in which 5 wt% of the monomer having an ethyl group as the R part of the side chain-containing EDT and 95 wt% of a 3,4-EDT monomer having no side chain is used. Produced. Example 3a is the same as Example 1 except that a monomer obtained by mixing 5 wt% of the monomer whose R portion of the side chain-containing EDT is a propyl group and 95 wt% of the 3,4-EDT monomer not containing the side chain is used. Produced.

  For Comparative Example 1 and Examples 1a to 3a, the capacitance value at 120 Hz, the equivalent series resistance (ESR) at 100 KHz, and the withstand voltage swept at 0.1 mV / sec were measured. Table 2 shows the comparison results of Examples 1a to 3a when Comparative Example 1 is 100.

Example 1b to Example 3b
Example 1b is the same as Example 1 except that a monomer obtained by mixing 50 wt% of a monomer in which the R part of the side chain-containing EDT is a methyl group and 50 wt% of a 3,4-EDT monomer not containing a side chain is used. Produced. Example 2b is the same as Example 1 except that a monomer obtained by mixing 50 wt% of a monomer in which the R part of the side chain-containing EDT is an ethyl group and 50 wt% of a 3,4-EDT monomer not containing a side chain is used. Produced. Example 3b is the same as Example 1 except that a monomer obtained by mixing 50 wt% of the monomer in which the R part of the side chain-containing EDT is a propyl group and 50 wt% of the 3,4-EDT monomer not containing a side chain was used. Produced.

  For Comparative Example 1 and Examples 1b to 3b, the capacitance value at 120 Hz, the equivalent series resistance (ESR) at 100 KHz, and the withstand voltage swept at 0.1 mV / sec were measured. Table 3 shows the comparison results of Examples 1b to 3b when Comparative Example 1 is set to 100.

Example 4 to Example 5
Example 4 is the same as Example 1 except that a monomer obtained by mixing 50 wt% of a monomer whose R part of the side chain-containing EDT is a methyl group and 50 wt% of a monomer whose R part of the side chain-containing EDT is an ethyl group is used. It produced similarly. Example 5 is the same as Example 1 except that a monomer obtained by mixing 50 wt% of the monomer whose side chain-containing EDT has an ethyl group and 50 wt% of a monomer whose side chain-containing EDT has a propyl group is used. It produced similarly.

  For Comparative Example 1 and Examples 4 to 5, the capacitance value at 120 Hz, the equivalent series resistance (ESR) at 100 KHz, and the withstand voltage swept at 0.1 mV / sec were measured. Table 4 shows the comparison results of Examples 4 to 5 when Comparative Example 1 is 100.

  From the results of Tables 1 to 4, it contains a side chain-containing 3,4-EDT polymer compared to a solid electrolytic capacitor (Comparative Example 1) containing a 3,4-EDT polymer that does not contain a side chain. It can be seen that the withstand voltage is improved in the solid electrolytic capacitors (Examples 1 to 5). In particular, from the results of Examples 1 to 3, it is understood that as the number of carbons in the hydrocarbon group R increases, the withstand voltage of the solid electrolytic capacitor improves, while the capacitance decreases and the ESR increases. it can. It can also be seen that the withstand voltage improves as the proportion of the side chain-containing 3,4-EDT in the monomer increases.

10: Capacitor element 11: Anode electrode foil 12: Cathode electrode foil 13: Separator 14: Lead terminal 17: Sealing rubber 18: Exterior case

Claims (8)

In a solid electrolytic capacitor formed by forming a solid electrolyte containing a conductive polymer in a capacitor element formed by winding or laminating an anode electrode layer having an oxide film and a cathode electrode layer via a separator,
The conductive polymer has the following formula (I):

A solid electrolytic capacitor characterized in that it is a polymer of a monomer containing a monomer represented by (wherein R is a hydrocarbon group having 1 to 10 carbon atoms). The conductive polymer is represented by the following formula (I) in all monomers for forming the conductive polymer:

2. The solid electrolytic capacitor according to claim 1, wherein the solid electrolytic capacitor contains 5 to 100% by weight of a monomer represented by (wherein R is a hydrocarbon group having 1 to 10 carbon atoms). The conductive polymer has the following formula (I):

3. The polymer according to claim 1, wherein the capacitor element is impregnated with a monomer containing a monomer represented by (wherein R is a hydrocarbon group having 1 to 10 carbon atoms) and an oxidizing agent. The solid electrolytic capacitor as described. Wherein R is a solid electrolytic capacitor according to any one of claims 1 to 3 is a hydrocarbon group having 1 to 3 carbon atoms. The anode electrode layer is an anode foil, the cathode electrode layer, a solid electrolytic capacitor according to any one of claims 1 to 4, which is a cathode electrode foil. On the anode electrode layer, the following formula (I):

(Wherein R is a hydrocarbon group having 1 to 10 carbon atoms), a carbon layer and a silver paste layer are sequentially formed as the cathode electrode layer, and the anode electrode layer the solid electrolytic capacitor according to any one of claims 1 to 5, characterized in that is obtained by laminating a plurality. In a method for producing a solid electrolytic capacitor in which a solid electrolyte containing a conductive polymer is formed in a capacitor element in which an anode electrode layer having an oxide film and a cathode electrode layer are wound or laminated with a separator interposed therebetween. ,
The following formula (I);

An impregnation step of impregnating a capacitor element with a monomer containing a monomer represented by (wherein R is a hydrocarbon group having 1 to 10 carbon atoms) and an oxidizing agent;
And a polymerization step of forming the solid electrolyte containing the conductive polymer by heating the capacitor element after the impregnation step. On the anode electrode layer, the following formula (I):

(Wherein R is a hydrocarbon group having 1 to 10 carbon atoms), a carbon layer and a silver paste layer are sequentially formed as the cathode electrode layer, and the anode electrode layer The method for producing a solid electrolytic capacitor according to claim 6, wherein a plurality of sheets are laminated.