Solid electrolytic capacitor and method for manufacturing solid electrolytic capacitor

Abstract

This solid electrolytic capacitor (100) includes a capacitor element (170) provided with a first electrode layer (141), a dielectric layer (150), a solid electrolyte layer (163), and a second electrode layer (160) formed on the outer surface of the solid electrolyte layer (163). The solid electrolyte layer (163) is formed of a polymer film containing: a crosslinked polymer obtained through crosslinking of a polymer having a carbonyl group by means of a crosslinking agent including a dihydrazide compound; and a complex formed of polyethylene dioxythiophene and polystyrene sulfonate. The second electrode layer (160) has a conductive polymer film (165) formed in contact with the solid electrolyte layer (163). The solid electrolyte layer (163) is a precoat layer used when forming the conductive polymer film (165) through electrolytic polymerization.

Description

Solid electrolytic capacitor and method for manufacturing the same

[0001] The present invention relates to a solid electrolytic capacitor and a method for manufacturing a solid electrolytic capacitor. This application claims priority to Japanese Patent Application No. 2024-055210, filed on March 29, 2024, the contents of which are incorporated herein by reference.

[0002] Solid electrolytic capacitors are widely used in various electronic devices. Some solid electrolytic capacitors have a structure in which an anode layer made of a valve metal such as aluminum or tantalum, a dielectric layer formed on the outer surface of the anode layer, a solid electrolyte layer formed on the outer surface of the dielectric layer, and a cathode layer formed on the outer surface of the solid electrolyte layer are sequentially stacked.

[0003] Conventional solid electrolytic capacitors include those described in Patent Documents 1 and 2. Patent Document 1 describes a solid electrolytic capacitor including an anode, a dielectric layer formed on the anode, a polyvinyl alcohol film formed on the dielectric layer, and a conductive polymer layer formed on the polyvinyl alcohol film.

[0004] Patent Document 2 describes a solid electrolytic capacitor including an element portion and a polymer disposed on or within the element portion. Patent Document 2 describes that the element portion includes an anode body, a dielectric layer formed on the surface of the anode body, a solid electrolyte layer covering at least a portion of the dielectric layer, and a cathode extraction layer covering at least a portion of the solid electrolyte layer. Patent Document 2 also describes that the polymer is disposed on or within the cathode extraction layer.

[0005] Furthermore, some conventional solid electrolytic capacitors have a solid electrolyte layer formed using an aqueous dispersion of a composite of polyethylenedioxythiophene and polystyrene sulfonic acid (hereinafter, sometimes referred to as "PEDOT / PSS").

[0006] Japanese Patent No. 5895227 Japanese Patent Application Laid-Open No. 2022-39775

[0007] A polymer film formed using an aqueous dispersion of PEDOT / PSS has good electrical conductivity and heat resistance, making it a desirable material for a solid electrolyte layer. However, a polymer film formed using an aqueous dispersion of PEDOT / PSS has insufficient water resistance. Therefore, in a solid electrolytic capacitor having a solid electrolyte layer made of a polymer film formed using a conventional aqueous dispersion of PEDOT / PSS, there is a demand for improving the water resistance of the solid electrolyte layer and improving durability.

[0008] In addition, the use of a conductive polymer film formed by electrolytic polymerization in contact with the outer surface of a solid electrolyte layer as an electrode for a solid electrolytic capacitor has been investigated. By using electrolytic polymerization, even if the outer surface of the solid electrolyte layer has a finely uneven shape, a conductive polymer film that covers the outer surface of the solid electrolyte layer can be formed along the surface shape of the outer surface of the solid electrolyte layer. Therefore, by forming an electrode in contact with the outer surface of the solid electrolyte layer using electrolytic polymerization, it becomes easier to obtain a solid electrolytic capacitor with even higher capacity and lower resistance.

[0009] Conductive polymer films that can be formed using electrolytic polymerization include those made of polymers having a pyrrole skeleton. In general, when forming a polypyrrole (PPy) film using electrolytic polymerization, manganese oxide (MnO ２ The material on which the precoat layer made of manganese oxide (MnO) is formed is immersed in a polymerization aqueous solution containing pyrrole and a dopant, and a polypyrrole film is grown on the surface to be formed. ２ The precoat layer is formed by applying an aqueous manganese sulfate solution or an aqueous manganese nitrate solution to the surface of the material to be coated, and then heat-treating the material at a high temperature of about 300°C.

[0010] Therefore, when a polypyrrole film formed by electrolytic polymerization is used as an electrode of a solid electrolytic capacitor, it is necessary to limit the materials used in manufacturing the solid electrolytic capacitor so that the heat treatment for forming a precoat layer made of manganese oxide on the surface on which the polypyrrole film is to be formed can be carried out without any problems.

[0011] As a method for forming a precoat layer of a polypyrrole film without heat treatment, it is possible to use a polymer film formed by applying an aqueous dispersion of PEDOT / PSS instead of a precoat layer made of manganese oxide.

[0012] However, polymer films formed using aqueous dispersions of PEDOT / PSS have insufficient water resistance. Therefore, when a polymer film formed using an aqueous dispersion of PEDOT / PSS is used as a precoat layer, the precoat layer dissolves in the aqueous polymerization solution containing pyrrole and a dopant when forming a polypyrrole film using electropolymerization. As a result, the electropolymerization reaction becomes unstable, and the polypyrrole film tends to form an island or mesh-like structure. This prevents the polypyrrole film from adequately covering the surface to be formed, making it difficult to obtain a solid electrolytic capacitor with sufficient capacitance.

[0013] The present invention has been made in view of the above-mentioned problems, and has an object to provide a solid electrolytic capacitor having a solid electrolyte layer made of a polymer film with good water resistance, in which a conductive polymer film that functions as an electrode can be stably formed by an electrolytic polymerization method using the solid electrolyte layer as a precoat layer, and a method for manufacturing the same.

[0014] In order to solve the above problems, the present invention provides the following means: A solid electrolytic capacitor according to a first aspect of the present invention includes a capacitor element including a first electrode layer, a dielectric layer formed on the outer surface of the first electrode layer, a solid electrolyte layer formed on the outer surface of the dielectric layer, and a second electrode layer formed on the outer surface of the solid electrolyte layer, wherein the solid electrolyte layer is made of a polymer film including a crosslinked polymer formed by crosslinking a polymer having a carbonyl group with a crosslinking agent made of a dihydrazide compound, and a composite of polyethylenedioxythiophene and polystyrenesulfonic acid, the second electrode layer has a conductive polymer film formed in contact with the solid electrolyte layer, and the solid electrolyte layer is a precoat layer used when forming the conductive polymer film by electrolytic polymerization.

[0015] A solid electrolytic capacitor according to a second aspect of the present invention includes a capacitor element including a first electrode layer, a dielectric layer formed on the outer surface of the first electrode layer, a solid electrolyte layer formed on the outer surface of the dielectric layer, and a second electrode layer formed on the outer surface of the solid electrolyte layer, wherein the solid electrolyte layer is made of a polymer film including a crosslinked polymer formed by crosslinking a composite of polyethylenedioxythiophene and polystyrene sulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton with a crosslinking agent, and the crosslinking agent is a compound selected from the group consisting of -NH ２ a —NH— group, and a salt of an amine compound containing a total of four or more groups selected from one or two types of groups, the —NH— group, the second electrode layer having a conductive polymer film formed in contact with the solid electrolyte layer, and the solid electrolyte layer being a precoat layer used when forming the conductive polymer film by electrolytic polymerization.

[0016] A solid electrolytic capacitor according to a third aspect of the present invention includes a capacitor element including: a first electrode layer; a dielectric layer formed on the outer surface of the first electrode layer; a solid electrolyte layer formed on the outer surface of the dielectric layer; and a second electrode layer formed on the outer surface of the solid electrolyte layer, wherein the solid electrolyte layer is a polymer film containing a crosslinked polymer formed by crosslinking a composite of polyethylenedioxythiophene and polystyrene sulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton with a crosslinking agent, the crosslinking agent being a metal salt containing a metal cation having a valence of two or more; the second electrode layer has a conductive polymer film formed in contact with the solid electrolyte layer; and the solid electrolyte layer is a precoat layer used when forming the conductive polymer film by electrolytic polymerization.

[0017] In the solid electrolytic capacitor according to an embodiment of the present invention, the solid electrolyte layer included in the capacitor element is made of a polymer film with good water resistance, and the second electrode layer includes a conductive polymer film. Therefore, the solid electrolyte layer of the solid electrolytic capacitor according to an embodiment of the present invention can be used as a precoat layer that is difficult to dissolve in a polymerization aqueous solution when forming a conductive polymer film in contact with the solid electrolyte layer by electropolymerization. Therefore, in the solid electrolytic capacitor according to an embodiment of the present invention, the conductive polymer film included in the second electrode layer can be stably formed by electropolymerization using the solid electrolyte layer as a precoat layer.

[0018] Fig. 1 is a schematic cross-sectional view showing a solid electrolytic capacitor according to a first embodiment of the present invention. Fig. 2 is an enlarged cross-sectional view showing an enlarged view of the area around symbol II in Fig. 1. Fig. 3 is a schematic cross-sectional view taken along line III-III shown in Fig. 1. Fig. 4 is a schematic cross-sectional view showing a solid electrolytic capacitor according to a fourth embodiment of the present invention.

[0019] The present invention includes the following aspects.

[0020] [1] A solid electrolytic capacitor including a capacitor element having: a first electrode layer; a dielectric layer formed on the outer surface of the first electrode layer; a solid electrolyte layer formed on the outer surface of the dielectric layer; and a second electrode layer formed on the outer surface of the solid electrolyte layer, wherein the solid electrolyte layer is made of a polymer film containing a crosslinked polymer obtained by crosslinking a polymer having a carbonyl group with a crosslinking agent made of a dihydrazide compound, and a composite of polyethylenedioxythiophene and polystyrenesulfonic acid, the second electrode layer having a conductive polymer film formed in contact with the solid electrolyte layer, and the solid electrolyte layer being a precoat layer used when forming the conductive polymer film by electrolytic polymerization.

[0021] [2] The solid electrolytic capacitor according to [1], wherein the polymer having a carbonyl group has a polyvinyl alcohol skeleton. [3] The solid electrolytic capacitor according to [1] or [2], wherein a ratio of the structural units derived from the polymer having a carbonyl group to a total mass of the structural units derived from the polymer having a carbonyl group forming the crosslinked polymer and the composite is 70 mass% or less, and a ratio of the structural units derived from the crosslinking agent to a mass of the structural units derived from the polymer having a carbonyl group is 15 mass% or less.

[0022] [4] The solid electrolytic capacitor according to [1] or [2], wherein the ratio of the structural units derived from the polymer having a carbonyl group to the total mass of the structural units derived from the polymer having a carbonyl group forming the crosslinked polymer and the composite is 30 mass% or less, and the ratio of the structural units derived from the crosslinking agent to the mass of the structural units derived from the polymer having a carbonyl group is 10 mass% or less.

[0023] [5] A capacitor element including: a first electrode layer; a dielectric layer formed on the outer surface of the first electrode layer; a solid electrolyte layer formed on the outer surface of the dielectric layer; and a second electrode layer formed on the outer surface of the solid electrolyte layer, wherein the solid electrolyte layer is made of a polymer film including a crosslinked polymer obtained by crosslinking a composite of polyethylenedioxythiophene and polystyrene sulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton with a crosslinking agent, and the crosslinking agent is a —NH ２ a salt of an amine compound containing a total of four or more groups selected from one or two types of groups selected from the group consisting of an —NH— group and an —NH— group, wherein the second electrode layer has a conductive polymer film formed in contact with the solid electrolyte layer, and the solid electrolyte layer is a precoat layer used when forming the conductive polymer film by electrolytic polymerization.

[0024] [6] A solid electrolytic capacitor including a capacitor element having: a first electrode layer; a dielectric layer formed on the outer surface of the first electrode layer; a solid electrolyte layer formed on the outer surface of the dielectric layer; and a second electrode layer formed on the outer surface of the solid electrolyte layer, wherein the solid electrolyte layer is a polymer film containing a crosslinked polymer formed by crosslinking a composite of polyethylenedioxythiophene and polystyrene sulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton with a crosslinking agent, and the crosslinking agent is a metal salt containing a metal cation having a valence of two or more; the second electrode layer has a conductive polymer film formed in contact with the solid electrolyte layer; and the solid electrolyte layer is a precoat layer used when forming the conductive polymer film by electrolytic polymerization.

[0025] [7] The solid electrolytic capacitor according to [6], wherein the cross-linking agent is calcium chloride.

[0026] [8] The solid electrolytic capacitor according to any one of [1] to [7], wherein the conductive polymer film is made of a polymer having a pyrrole skeleton. [9] The solid electrolytic capacitor according to any one of [1] to [8], wherein the first electrode layer is made of aluminum foil.

[10] The solid electrolytic capacitor according to any one of [1] to [8], wherein the first electrode layer is a block-shaped layer made of tantalum or niobium.

[0027]

[11] A method for manufacturing a solid electrolytic capacitor, comprising: a dielectric layer forming step of forming a dielectric layer on the outer surface of a first electrode layer; a solid electrolyte layer forming step of forming a solid electrolyte layer on the outer surface of the dielectric layer, the solid electrolyte layer comprising a polymer film containing a crosslinked polymer obtained by crosslinking a polymer having a carbonyl group with a crosslinking agent made of a dihydrazide compound, and a composite of polyethylene dioxythiophene and polystyrene sulfonic acid; and a second electrode layer forming step of forming a conductive polymer film on the outer surface of the solid electrolyte layer by electrolytic polymerization using the solid electrolyte layer as a precoat layer, to form a second electrode layer having the conductive polymer film.

[0028]

[12] A dielectric layer forming step of forming a dielectric layer on the outer surface of a first electrode layer, and forming a composite of polyethylenedioxythiophene and polystyrene sulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton on the outer surface of the dielectric layer, ２ a second electrode layer forming step of forming a second electrode layer having a conductive polymer film on an outer surface of the solid electrolyte layer by electrolytic polymerization using the solid electrolyte layer as a precoat layer.

[0029]

[13] A method for manufacturing a solid electrolytic capacitor, comprising: a dielectric layer forming step of forming a dielectric layer on the outer surface of a first electrode layer; a solid electrolyte layer forming step of forming a solid electrolyte layer on the outer surface of the dielectric layer, the solid electrolyte layer being made of a polymer film including a crosslinked polymer obtained by crosslinking a composite of polyethylenedioxythiophene and polystyrene sulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton with a crosslinking agent made of a metal salt including a metal cation having a valence of two or more; and a second electrode layer forming step of forming a conductive polymer film on the outer surface of the solid electrolyte layer by electrolytic polymerization using the solid electrolyte layer as a precoat layer, to form a second electrode layer having the conductive polymer film.

[0030] The solid electrolytic capacitor of this embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity. Therefore, the dimensional ratios of the components may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited to them. Appropriate modifications can be made within the scope of the present invention.

[0031] [First embodiment] (Solid electrolytic capacitor) Fig. 1 is a schematic cross-sectional view showing a solid electrolytic capacitor according to a first embodiment of the present invention. Fig. 2 is an enlarged cross-sectional view showing an area around the symbol II in Fig. 1. Fig. 3 is a schematic cross-sectional view taken along the line III-III shown in Fig. 1.

[0032] 1 and 3, the symbol T indicates the thickness direction of the capacitor element 170. In Fig. 1, the symbol L indicates the length direction perpendicular to the thickness direction T of the capacitor element 170. In Fig. 3, the symbol W indicates the width direction of the capacitor element 170, which is the direction perpendicular to the thickness direction T and the length direction L of the capacitor element 170.

[0033] 1 to 3 includes a resin mold layer 110 having a substantially rectangular parallelepiped outer shape, a plurality of capacitor elements 170 (four in FIG. 1 ) provided inside the resin mold layer 110, a first terminal 120, and a second terminal 130. The resin mold layer 110 forms the exterior of the solid electrolytic capacitor 100. The resin mold layer 110 is made of an insulating resin material containing, for example, a resin such as an epoxy resin and a filler such as silica.

[0034] The first terminal 120 is made of a conductive material such as Cu. The first terminal 120 is electrically connected to the second electrode layer 160 of each of the plurality of capacitor elements 170 and is extended to the outside of the resin mold layer 110. The portion of the first terminal 120 located outside the resin mold layer 110 is bent along the outer surface of the resin mold layer 110.

[0035] The second terminal 130 is made of a conductive material such as Cu. The second terminal 130 is electrically connected to the first electrode layer 141 of each of the plurality of capacitor elements 170 and is extended to the outside of the resin mold layer 110. The portion of the second terminal 130 located outside the resin mold layer 110 is bent along the outer surface of the resin mold layer 110.

[0036] 1 and 3, the plurality of capacitor elements 170 included in the solid electrolytic capacitor 100 are stacked in the thickness direction T. The number of capacitor elements 170 included in the solid electrolytic capacitor 100 of this embodiment is not particularly limited, and may be four as shown in FIGS. 1 and 3, one to three, or five or more.

[0037] 1 and 3, the plurality of capacitor elements 170 are electrically connected to one another by connecting conductor layers 190. Examples of connecting conductor layers 190 include a conductive adhesive containing Ag. Furthermore, as shown in FIG. 1, the ends of the first electrode layers 141 of the capacitor elements 170 adjacent to one another in the stacking direction on the side of the second terminal 130 are electrically connected to one another by resistance welding or the like.

[0038] As shown in Figures 1 and 2, each capacitor element 170 includes a first electrode layer 141, a dielectric layer 150 formed on the outer surface of the first electrode layer 141, a solid electrolyte layer 163 formed on the outer surface of the dielectric layer 150, and a second electrode layer 160 formed on the outer surface of the solid electrolyte layer 163.

[0039] (First Electrode Layer 141) The first electrode layer 141 functions as an anode in the solid electrolytic capacitor 100. The first electrode layer 141 is made of a metal foil having a finely textured surface, as shown in Fig. 2. The finely textured surface of the first electrode layer 141 increases the surface area of ​​the first electrode layer 141, thereby increasing the capacity of the solid electrolytic capacitor 100.

[0040] Metal foil made of a valve metal such as aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, or antimony can be used as the first electrode layer 141. Of the metal foils made of the above valve metals, it is preferable to use aluminum foil as the first electrode layer 141. This is because the dielectric layer 150 can be stably formed on the outer surface of the first electrode layer 141 by anodizing the outer surface of the first electrode layer 141.

[0041] When the first electrode layer 141 is an aluminum foil, it preferably has an average thickness of 70 μm to 220 μm. If the average thickness of the aluminum foil is 70 μm or more, the first electrode layer 141 has sufficient strength and the solid electrolytic capacitor 100 has sufficient capacitance. Furthermore, if the average thickness of the aluminum foil is 220 μm or less, the first electrode layer 141 can be easily electrically connected to the second terminal 130.

[0042] (Dielectric Layer 150) As shown in Fig. 2, the dielectric layer 150 is formed so as to cover the first electrode layer 141, following the irregularities on the outer surface of the first electrode layer 141. The dielectric layer 150 is made of a metal oxide film having electrical insulation properties. For example, when the first electrode layer 141 is an aluminum foil, the dielectric layer 150 is preferably made of an aluminum oxide film. The thickness of the dielectric layer 150 is usually 1 nm to 1 µm.

[0043] 2, the solid electrolyte layer 163 is formed along the outer surface of the dielectric layer 150, which is formed along the uneven shape of the outer surface of the first electrode layer 141. That is, the solid electrolyte layer 163 is formed along the fine recesses formed in the outer surface of the first electrode layer 141, with the dielectric layer 150 interposed therebetween. The solid electrolyte layer 163 in this embodiment is used as a precoat layer when the conductive polymer film 165 of the second electrode layer 160 is formed by electrolytic polymerization, and is made of the polymer film described below.

[0044] [Polymer Film] The polymer film forming the solid electrolyte layer 163 includes a crosslinked polymer in which a polymer having a carbonyl group is crosslinked with a crosslinking agent made of a dihydrazide compound, and a composite of polyethylenedioxythiophene and polystyrene sulfonic acid (PEDOT / PSS) represented by the following formula (1):

[0045] (n in formula (1) １ and m １ indicates the number of repeating units.)

[0046] (Crosslinked Polymer) The crosslinked polymer contained in the polymer film of this embodiment is obtained by crosslinking the carbonyl group of a polymer having a carbonyl group with the dihydrazide group of a dihydrazide compound, which is a crosslinking agent, through a crosslinking reaction. The crosslinked polymer has a three-dimensional network structure and has excellent water resistance, and holds the PEDOT / PSS contained in the polymer film, thereby imparting water resistance to the polymer film of this embodiment. The crosslinked polymer contained in the polymer film of this embodiment may be of only one type, or may be of two or more types.

[0047] Examples of polymers having a carbonyl group (—O—C(═O)R) that can be used to form a crosslinked polymer include water-soluble polymers having a carbonyl group, such as polyvinyl alcohol resins, polyacrylamide resins, polyethylene glycol resins, and cellulose resins.

[0048] Among these, it is preferable to use a polymer having a polyvinyl alcohol skeleton as the polymer having a carbonyl group. A crosslinked polymer in which a polymer having a polyvinyl alcohol skeleton is crosslinked with a crosslinking agent made of a dihydrazide compound has good water resistance. Therefore, a polymer film containing a crosslinked polymer in which a polymer having a polyvinyl alcohol skeleton is crosslinked has even better water resistance. Furthermore, since an aqueous solution of a polymer having a polyvinyl alcohol skeleton can be easily mixed with an aqueous dispersion of PEDOT / PSS, a polymer film can be efficiently formed when producing a polymer film by the production method described below.

[0049] In particular, it is preferable to use a modified polyvinyl alcohol represented by the following formula (2), in which a carbonyl group is bonded to a polyvinyl alcohol skeleton, as the polymer having a carbonyl group, because it has good reactivity with a crosslinking agent made of a dihydrazide compound, and a polymer film having better water resistance is easily obtained.

[0050] (n in formula (2) ２ and m ２ indicates the number of repeating units, and n ２ +m ２is 100 to 5000. R is a monovalent substituent.

[0051] When a modified polyvinyl alcohol represented by formula (2) is used as the polymer having a carbonyl group (—O—C(═O)R), n ２ +m ２ The average degree of polymerization of the modified polyvinyl alcohol represented by the formula (2) (n ２ +m ２ When the average degree of polymerization of the modified polyvinyl alcohol represented by formula (2) is 5000 or less, the modified polyvinyl alcohol can be easily mixed with an aqueous dispersion of PEDOT / PSS, and when a polymer film is produced by the production method described below, the polymer film can be efficiently formed.

[0052] The saponification degree of the modified polyvinyl alcohol represented by the formula (2) [[n ２ / (n ２ +m ２ ) × 100] is preferably 95% to 99%. When the saponification degree is 95% or higher, the hydrophilicity of the modified polyvinyl alcohol represented by formula (2) is improved, allowing for the formation of an aqueous solution that is more easily mixed with the aqueous dispersion of PEDOT / PSS. Furthermore, when the saponification degree is 99% or lower, the hydrophobicity-improving effect due to the presence of -O-OC(=O)R groups in the modified polyvinyl alcohol represented by formula (2) is fully obtained. As a result, a polymer film with better water resistance is more likely to be obtained.

[0053] The modified polyvinyl alcohol represented by formula (2) preferably has a carbonyl group (—O—C(═O)R), for example, where the monovalent substituent represented by R in formula (2) is any one selected from alkyl groups having 1 to 5 carbon atoms. R in formula (2) is particularly preferably a methyl group because it is a functional group that has good reactivity with the dihydrazide compound, which is a crosslinking agent.

[0054] In this embodiment, the polymer having a carbonyl group (—O—C(═O)R) used as a material for forming the crosslinked polymer may be of one type or two or more types.

[0055] As the crosslinking agent made of a dihydrazide compound used in forming a crosslinked polymer, known dihydrazide compounds can be used, such as adipic acid dihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide, 7,11-octadecadiene-1,18-dicarbohydrazide, etc. Among these, as the crosslinking agent made of a dihydrazide compound, it is preferable to use adipic acid dihydrazide represented by the following formula (3) and / or 7,11-octadecadiene-1,18-dicarbohydrazide represented by the following formula (4), because they have good reactivity with polymers having carbonyl groups.

[0056] In the present embodiment, the cross-linking agent made of a dihydrazide compound used as a material for forming a cross-linked polymer may be of one type only, or may be of two or more types.

[0057]

[0058] In this embodiment, for example, when a modified polyvinyl alcohol represented by formula (2) is used as the polymer having a carbonyl group and adipic acid dihydrazide represented by formula (3) is used as the cross-linking agent made of a dihydrazide compound, a cross-linked polymer is formed as shown below.

[0059] That is, a crosslinking reaction occurs between the carbonyl group of the modified polyvinyl alcohol represented by formula (2) and the dihydrazide group of the adipic acid dihydrazide represented by formula (3), and the modified polyvinyl alcohol represented by formula (2) is crosslinked by the adipic acid dihydrazide represented by formula (3), forming water and a crosslinked polymer containing a crosslinked structure represented by the following formula (5).

[0060] (R in formula (5) is a monovalent substituent.)

[0061] In the polymer film of this embodiment, the ratio of the structural units derived from the polymer having a carbonyl group to the total mass of the structural units derived from the polymer having a carbonyl group forming the crosslinked polymer and PEDOT / PSS is preferably 70% by mass or less, more preferably 30% by mass or less. If the ratio of the structural units derived from the polymer having a carbonyl group is 70% by mass or less, this prevents the conductivity of the polymer film from being impaired due to an excessive proportion of structural units derived from the polymer having a carbonyl group. The ratio of the structural units derived from the polymer having a carbonyl group to the total mass is preferably 5% by mass or more, more preferably 10% by mass or more, since this ensures the content of the crosslinked polymer contained in the polymer film and makes it easier to obtain a polymer film with better water resistance.

[0062] In the polymer membrane of this embodiment, the ratio of structural units derived from the polymer having a carbonyl group to the total mass is preferably 70% by mass or less, and the ratio of structural units derived from the crosslinking agent to the mass of structural units derived from the polymer having a carbonyl group is preferably 15% by mass or less. Furthermore, it is more preferable that the ratio of structural units derived from the polymer having a carbonyl group is 30% by mass or less, and the ratio of structural units derived from the crosslinking agent is 10% by mass or less. When the ratio of structural units derived from the crosslinking agent is 15% by mass or less, the conductivity of the polymer membrane can be prevented from being impaired by the presence of many structural units derived from the crosslinking agent that do not form a crosslinked structure with the structural units derived from the polymer having a carbonyl group. The ratio of structural units derived from the crosslinking agent to the mass of structural units derived from the polymer having a carbonyl group is preferably 3% by mass or more, more preferably 5% by mass or more, since this ensures the content of crosslinked polymers contained in the polymer membrane and makes it easier to obtain a polymer membrane with better water resistance.

[0063] The content of PEDOT / PSS in the polymer film of this embodiment is preferably 30% by mass or more, and more preferably 60% by mass or more. This is because a polymer film with good conductivity is obtained when the content of PEDOT / PSS is 30% by mass or more. Furthermore, the content of PEDOT / PSS in the polymer film is preferably 85% by mass or less, and more preferably 75% by mass or less. This is because a polymer film with a sufficient amount of crosslinked polymer and good water resistance is more easily obtained when the content of PEDOT / PSS is 85% by mass or less.

[0064] The ratio of the structural units derived from the polymer having a carbonyl group to the total mass in the polymer film of this embodiment corresponds to the ratio of the polymer having a carbonyl group to the total mass of PEDOT / PSS and the polymer having a carbonyl group in the solid content of the raw material to be the polymer film. Also, the ratio of the structural units derived from the crosslinker to the mass of the structural units derived from the polymer having a carbonyl group in the polymer film of this embodiment corresponds to the ratio of the mass of the crosslinker to the mass of the polymer having a carbonyl group in the solid content of the raw material to be the polymer film.

[0065] The polymer membrane of this embodiment contains the crosslinked polymer described above and PEDOT / PSS represented by formula (1). In addition, one or more other components may be further contained as needed depending on the intended use of the polymer membrane. Examples of such other components include known crosslinking agents other than dihydrazide compounds, known polymers without carbonyl groups, etc. As known polymers without carbonyl groups, water-soluble or water-dispersible polymers can be preferably used, and specific examples thereof include sulfonated polyester resins.

[0066] The polymer film of this embodiment includes a crosslinked polymer in which a polymer having a carbonyl group is crosslinked with a crosslinking agent made of a dihydrazide compound, and PEDOT / PSS, thereby providing the polymer film with excellent electrical conductivity, heat resistance, and water resistance.

[0067] It is preferable that the solid electrolyte layer 163 is formed along fine recesses formed on the outer surface of the first electrode layer 141 via the dielectric layer 150. The reason for this is that by using the solid electrolyte layer 163 as a precoat layer and forming the conductive polymer film 165, which will be described later, in contact with the solid electrolyte layer 163 by electrolytic polymerization, the conductive polymer film 165 can be obtained that covers the solid electrolyte layer 163 at a high coverage rate, conforming to the shape of the outer surface of the solid electrolyte layer 163.

[0068] Furthermore, in this embodiment, the solid electrolyte layer 163 is preferably formed by laminating multiple layers of polymer films with different components. The reason for this is that, for example, by making the first polymer film disposed on the dielectric layer 150 side to be easily formed in minute recesses present on the outer surface of the dielectric layer 150, and by making the second polymer film disposed on the second electrode layer 160 side of the first polymer film to be highly water-resistant and easily formed with a sufficient thickness on the first polymer film, a more reliable solid electrolytic capacitor 100 can be obtained.

[0069] In the present embodiment, when the solid electrolyte layer 163 is composed of two polymer layers, a first polymer film disposed on the dielectric layer 150 side and a second polymer film having a different composition from the first polymer film and disposed on the second electrode layer 160 side, at least one of the first polymer film and the second polymer film may be a polymer film containing the crosslinked polymer and PEDOT / PSS. When only one of the first polymer film and the second polymer film is the polymer film, it is preferable that only the second polymer film is a polymer film containing the crosslinked polymer and PEDOT / PSS. This is because the solid electrolyte layer 163 has good water resistance and is more suitable as a precoat layer when forming the conductive polymer film 165 of the second electrode layer 160 using an electrolytic polymerization method.

[0070] In the present embodiment, when the solid electrolyte layer 163 is composed of two polymer films, and only the second polymer film is a polymer film containing the above-mentioned cross-linked polymer and PEDOT / PSS, the first polymer film can be, for example, PEDOT / PSS and / or a sulfonic acid compound having a polyethylenedioxythiophene (PEDOT) skeleton represented by the following formula (6):

[0071] Among these polymer films, it is particularly preferable to use, as the first polymer film, one made of a sulfonic acid compound having a PEDOT skeleton represented by the following formula (6). This is because, compared with a polymer film containing the above-mentioned crosslinked polymer and PEDOT / PSS, a polymer film made of a sulfonic acid compound having a PEDOT skeleton represented by formula (6) is more likely to penetrate into minute recesses present on the outer surface of the dielectric layer 150, and also has good adhesion to a polymer film containing the above-mentioned crosslinked polymer and PEDOT / PSS. Therefore, when the conductive polymer film 165 of the second electrode layer 160 is formed by electrolytic polymerization using such a solid electrolyte layer 163 as a precoat layer, it becomes easier to obtain a conductive polymer film 165 with a large surface area that conforms to the shape of the outer surface of the solid electrolyte layer 163 and covers the solid electrolyte layer 163 at a high coverage rate, thereby making it easier to obtain a solid electrolytic capacitor with even higher capacitance.

[0072] (n in formula (6) ３ indicates the number of repeating units. ３ is a divalent linking group. ３ is a hydrogen atom.)

[0073] In the sulfonic acid compound having a PEDOT skeleton represented by formula (6) forming the first polymer film, n ３ The number of repeating units represented by the formula (6) can be, for example, 2 to 50, preferably 2 to 20, and more preferably 2 to 10. ３ When the number of repeating units represented by the formula (6) is 2 or more, a first polymer film having good film-forming properties can be obtained, and the solid electrolyte layer 163 has better water resistance. ３When the number of repeating units represented by the formula (I) is 10 or less, the first polymer film can more easily penetrate into minute recesses present in the outer surface of the dielectric layer 150. As a result, by forming the conductive polymer film 165 by electrolytic polymerization using the solid electrolyte layer 163 as a precoat layer, it becomes easier to obtain the second electrode layer 160 having a larger surface area.

[0074] In the sulfonic acid compound having a PEDOT skeleton represented by formula (6) forming the first polymer film, R ３ is a divalent linking group, and is preferably a divalent linking group having 1 to 6 carbon atoms. ３ Examples of the alkyl group include a paraphenylene group, (-CH ２ -)r (where r is 1 to 6), which are sulfonic acid compounds that are easily soluble in water, ２ -)r (wherein r is 1 or 2) is preferred.

[0075] The first polymer film may contain a surface tension adjuster made of a low-molecular-weight additive such as glycerin, ethylene glycol, etc. The surface tension adjuster adjusts the surface tension of the resin paint used to form the first polymer film to a suitable range, thereby making it easier for the resin paint to fill minute recesses present on the outer surface of the dielectric layer 150.

[0076] 1, in capacitor element 170, solid electrolyte layer 163 is not provided on the end of the outer surface of first electrode layer 141 that is connected to second terminal 130. As shown in FIGS. 1 and 2, the region of the outer surface of first electrode layer 141 that is not provided with solid electrolyte layer 163 is covered with insulating resin layer 151. As insulating resin layer 151, for example, a layer made of an insulating resin such as polyimide resin, polyamide resin, epoxy resin, acrylic resin, or silicone resin can be used.

[0077] 2 , the second electrode layer 160 formed on the outer surface of the solid electrolyte layer 163 is made of a conductive polymer film 165, a carbon layer 161 formed on the outer surface of the conductive polymer film 165, and a metal layer 162 formed on the outer surface of the carbon layer 161. In this embodiment, the second electrode layer 160 is described as being made up of three layers, namely, the conductive polymer film 165, the carbon layer 161, and the metal layer 162. However, the second electrode layer may have a single-layer structure made up of only the conductive polymer film 165, or a multi-layer structure made up of four or more layers made up of the conductive polymer film 165 and multiple carbon layers 161 and / or metal layers 162.

[0078] 2, the conductive polymer film 165 is formed so as to fill minute recesses formed on the outer surface of the first electrode layer 141. The conductive polymer film 165 is formed by electrolytic polymerization using the solid electrolyte layer 163 as a precoat layer. Therefore, the conductive polymer film 165 is made of a conductive polymer that can be electrolytically polymerized.

[0079] The conductive polymer film 165 can be made of a polymer having a skeleton selected from, for example, a pyrrole skeleton, a thiophene skeleton, a furan skeleton, an aniline skeleton, an acetylene skeleton, a phenylene skeleton, a phenylene vinylene skeleton, a thiophene vinylene skeleton, etc., and which may have a substituent. Among these polymers, the conductive polymer film 165 is preferably made of a polymer having a pyrrole skeleton, and more preferably polypyrrole. This is because the conductive polymer film 165 made of polypyrrole can be easily produced using an electrolytic polymerization method.

[0080] The conductive polymer film 165 may contain a dopant. The dopant that may be contained in the conductive polymer film 165 may be a monomolecular anion or a polymer anion. Only one type of dopant may be used alone, or two or more types may be used in combination.

[0081] Specific examples of the unimolecular anion include paratoluenesulfonic acid, alkylnaphthalenesulfonic acid or alkylnaphthalenesulfonate represented by the following formula (7).

[0082] (R in formula (7) ４ is an alkyl group. ４ is a hydrogen atom or a sodium atom.)

[0083] In the alkylnaphthalenesulfonic acid or alkylnaphthalenesulfonate represented by formula (7), R ４ Examples of the alkyl group represented by formula (7) include a methyl group and an ethyl group, and a methyl group is particularly preferred since it is easily soluble in water. ４ The alkyl group represented by the formula (I) is the alkyl group represented by the formula (I) in the -SO ３ X ４ and the carbon atom forming the benzene ring to which the group represented by the formula (I) is not bonded, and which is not shared by the two benzene rings.

[0084] In the alkylnaphthalenesulfonic acid or alkylnaphthalenesulfonate represented by formula (7), —SO ３ X ４ is a group represented by the formula (I) where R ４ and may be bonded to any carbon atom forming a benzene ring to which an alkyl group represented by the formula (I) is not bonded, and which is not shared by two benzene rings.

[0085] An example of using two or more compounds as a dopant is an alkylnaphthalenesulfonic acid or alkylnaphthalenesulfonate represented by the following formula (7): ４ and / or an alkyl group represented by —SO ３ X ４ and / or two or more compounds which are different in the type of group represented by the formula (I) and / or the position at which the group is bonded to the naphthalene ring.

[0086] The polymeric anion may be a polymer of a single monomer or a copolymer of two or more monomers. Specific examples of the polymeric anion include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-thylpropane sulfonic acid), polyisoprene sulfonic acid, and polyacrylic acid.

[0087] The carbon layer 161 contains a carbon material and may contain a binder resin and / or an additive, as necessary. Examples of carbon materials used in the carbon layer 161 include graphite, carbon black, graphene flakes, and carbon nanotubes. Examples of binder resins that may be contained in the carbon layer 161 include known thermoplastic resins or curable resins that can be used as binder resins. Examples of additives that may be contained in the carbon layer 161 include dispersants, surfactants, antioxidants, preservatives, bases, and / or acids.

[0088] The metal layer 162 can be a metal layer made of any metal selected from Ag, Cu, Ni, Sn, Zn, Pd, and Au, and is preferably an Ag layer or a Cu layer because of its good conductivity. If the metal layer 162 is a Cu layer, the solid electrolytic capacitor 100 will have good conductivity and even better water resistance. Furthermore, if the metal layer 162 is a Cu layer, the solid electrolytic capacitor 100 will have even better water resistance and durability, so it is more preferable that the metal layer 162 be disposed as the outermost layer of the second electrode layer 160.

[0089] (Method for Manufacturing a Solid Electrolytic Capacitor) To manufacture the solid electrolytic capacitor 100 of this embodiment, first, a plurality of capacitor elements 170 are manufactured. First, a first electrode layer 141 made of a metal foil having a finely textured surface is prepared. The first electrode layer 141 can be formed by subjecting the surface of the metal foil to a surface roughening treatment or a surface enlarging treatment using a known method.

[0090] (Dielectric Layer Forming Process) Next, a dielectric layer 150 is provided on the outer surface of the first electrode layer 141. The dielectric layer 150 can be formed by a method of oxidizing the surface layer of the first electrode layer 141. For example, when the first electrode layer 141 is an aluminum foil, the dielectric layer 150 made of an aluminum oxide film can be formed on the outer surface of the first electrode layer 141 by a method of immersing the aluminum foil in an ammonium adipate aqueous solution to perform anodizing treatment.

[0091] Next, an insulating resin layer 151 is formed on the end of the outer surface of the dielectric layer 150 that is connected to the second terminal 130 (i.e., the area where the solid electrolyte layer 163 is not formed). The insulating resin layer 151 can be formed by applying paint containing an insulating resin such as polyimide resin, polyamide resin, epoxy resin, acrylic resin, or silicone resin using a known method, followed by drying and curing.

[0092] (Solid Electrolyte Layer (Polymer Film) Formation Process) Next, a solid electrolyte layer 163 made of a polymer film containing a crosslinked polymer and PEDOT / PSS is provided on the outer surface of the dielectric layer 150 by the method described below. First, an aqueous dispersion of PEDOT / PSS, an aqueous solution of a polymer having a carbonyl group, an aqueous solution of a dihydrazide compound as a crosslinking agent, and other components that may be included as necessary are mixed and stirred to form a resin coating material.

[0093] When producing a resin coating, the order in which the aqueous dispersion of PEDOT / PSS, the aqueous solution of the polymer having a carbonyl group, and the aqueous solution of the dihydrazide compound as a cross-linking agent are mixed is not particularly limited. For example, all of the materials used in the resin coating may be mixed and stirred at the same time, or the resin coating may be produced by mixing the aqueous dispersion of PEDOT / PSS and the aqueous solution of the polymer having a carbonyl group to form a mixed liquid, and then mixing the mixed liquid with an aqueous solution of the dihydrazide compound as a cross-linking agent.

[0094] The concentrations of PEDOT / PSS in the aqueous dispersion of PEDOT / PSS used in producing the resin coating in this embodiment, the concentration of the polymer having a carbonyl group in the aqueous solution of the polymer having a carbonyl group, and the concentration of the dihydrazide compound in the aqueous solution of the dihydrazide compound are not particularly limited and can be set to concentrations that make mixing and stirring easy. The concentrations of PEDOT / PSS, the polymer having a carbonyl group, and the dihydrazide compound contained in the resin coating are set to concentrations that correspond to the proportion of PEDOT / PSS in the polymer film, the proportion of structural units derived from the polymer having a carbonyl group contained in the polymer film, and the proportion of structural units derived from the crosslinker, respectively.

[0095] The aqueous dispersion of PEDOT / PSS used in producing the resin coating can be one consisting of only PEDOT / PSS and water. The aqueous dispersion of PEDOT / PSS may contain, in addition to PEDOT / PSS and water, one or more of the other components described above. Specifically, the aqueous dispersion of PEDOT / PSS may contain PEDOT / PSS, water, and a sulfonated polyester resin, which is a polymer having no carbonyl groups.

[0096] Next, the resin paint prepared in this manner is applied to the outer surface of the dielectric layer 150, excluding the end connected to the second terminal 130 (i.e., the area where the insulating resin layer 151 is not formed), to form a coating film. The resin paint can be applied to the outer surface of the dielectric layer 150 by known methods such as immersing the area of ​​the first electrode layer 141, on whose outer surface the dielectric layer 150 and the insulating resin layer 151 are formed, where the insulating resin layer 151 is not formed, in the resin paint, dispensing, screen printing, or spray coating. A preferred method for applying the resin paint to the outer surface of the dielectric layer 150 is to immerse the area of ​​the dielectric layer 150 formed on the outer surface of the first electrode layer 141, where the solid electrolyte layer 163 is to be formed, in the resin paint. This is because the resin paint can be easily applied to the fine recesses present in the outer surface of the dielectric layer 150.

[0097] Next, the coating film formed on the outer surface of the dielectric layer 150 is dried to remove water from the coating film, which causes a reaction between the carbonyl group of the carbonyl-containing polymer and the dihydrazide group of the dihydrazide compound, which is a crosslinking agent, in the coating film to form a crosslinked polymer having a crosslinked structure, thereby forming the polymer film of this embodiment containing PEDOT / PSS and the crosslinked polymer.

[0098] As a method for removing water from the coating film, a known method such as heat treatment at a temperature of 80°C to 150°C can be used, and the method can be appropriately determined depending on the composition of the resin coating material, the thickness of the coating film, etc.

[0099] In this embodiment, the polymer membrane obtained by removing the water from the coating film may be washed. The polymer membrane can be washed using, for example, water. This is because the polymer membrane of this embodiment has good water resistance. By performing the above steps, a solid electrolyte layer 163 made of a polymer membrane is formed.

[0100] The solid electrolyte layer 163 made of the polymer membrane of this embodiment may be manufactured by applying the above-described resin coating to form a coating film and then removing the water from the coating film, either once or by repeating the above steps multiple times to form a polymer membrane of a predetermined thickness. Because the polymer membrane of this embodiment has good water resistance, repeating the above steps multiple times makes it easy to obtain a polymer membrane with a uniform, sufficient thickness and high coverage. This is because the polymer membrane's good water resistance makes it less likely for the polymer membrane to be dissolved by the water contained in the resin coating, even if a resin coating is applied to the polymer membrane in the second or subsequent steps.

[0101] On the other hand, if the water resistance of the polymer film is insufficient, for example, when a resin coating is applied to the polymer film formed in the first step in the second step, the polymer film formed in the first step will re-elute and fall off in part or in whole, resulting in an uneven or insufficient thickness of the polymer film formed in the second step.

[0102] Furthermore, when the solid electrolyte layer 163 in this embodiment is composed of two polymer films, a first polymer film disposed on the dielectric layer 150 side and a second polymer film disposed on the second electrode layer 160 side, it can be manufactured, for example, by the method shown below. When both the first polymer film and the second polymer film are polymer films containing the above-mentioned crosslinked polymer and PEDOT / PSS, the first polymer film is manufactured using the above-mentioned method for manufacturing the solid electrolyte layer 163 composed of a single polymer film. Thereafter, a second polymer film can be manufactured in the same manner as the first polymer film on the outer surface of the dielectric layer 150 on which the first polymer film has been formed, using a resin paint having different components from the resin paint used in manufacturing the first polymer film.

[0103] Furthermore, when only the second polymer film of the first and second polymer films is a polymer film containing the above-mentioned crosslinked polymer and PEDOT / PSS, it can be produced using the following method: First, as the resin coating material to be used in producing the first polymer film, for example, a resin coating material containing an aqueous dispersion of PEDOT / PSS and other components as needed, but not containing an aqueous solution of a polymer having a carbonyl group or an aqueous solution of a dihydrazide compound, or a resin coating material consisting of an aqueous solution of a sulfonic acid compound having a PEDOT skeleton represented by formula (6) is prepared.

[0104] Next, a resin coating is applied to the outer surface of the dielectric layer 150 using the same method as the method for manufacturing the solid electrolyte layer 163 consisting of a single polymer film described above, except that the resin coating prepared in this manner is used. Next, the coating film formed on the outer surface of the dielectric layer 150 is dried to remove water from the coating film. This produces a first polymer film. The method for removing water from the coating film can be determined appropriately depending on the composition of the resin coating used to form the first polymer film, the thickness of the coating film, etc.

[0105] Next, a second polymer film is produced on the outer surface of the dielectric layer 150 on which the first polymer film has been formed, using the same method as the method for producing the solid electrolyte layer 163 made of a single layer of polymer film described above. This results in a solid electrolyte layer 163 made of the first polymer film and the second polymer film, with only the second polymer film being a polymer film containing the cross-linked polymer and PEDOT / PSS.

[0106] As described above, the solid electrolyte layer 163 of this embodiment is made of manganese oxide (MnO ２ Therefore, the solid electrolytic capacitor 100 of this embodiment can be formed without a high-temperature heat treatment, unlike the case of forming a precoat layer made of manganese oxide (MnO ２ ) is formed, the degree of freedom in selecting materials for manufacturing the solid electrolytic capacitor 100 is high.

[0107] (Second Electrode Layer Forming Process) Next, the second electrode layer 160 is provided on the outer surface of the solid electrolyte layer 163. In the present embodiment, when the second electrode layer 160 is made of a conductive polymer film 165, a carbon layer 161 formed on the outer surface of the conductive polymer film 165, and a metal layer 162 formed on the outer surface of the carbon layer 161, it can be manufactured, for example, by the method shown below.

[0108] The conductive polymer film 165 is formed by electrolytic polymerization using the solid electrolyte layer 163 as a precoat layer. Specifically, for example, when a polypyrrole (PPy) film is formed as the conductive polymer film 165, an aqueous polymerization solution containing pyrrole and a dopant such as alkylnaphthalenesulfonic acid represented by formula (7) is prepared.

[0109] The concentrations of pyrrole and dopant in the aqueous polymerization solution containing pyrrole and dopant can be known concentrations and are not particularly limited. The content of pyrrole contained in the aqueous solution is, for example, preferably 10 mmol / L to 5000 mmol / L, more preferably 50 mmol / L to 500 mmol / L. The content of dopant contained in the aqueous solution is, for example, preferably 10 mmol / L to 3000 mmol / L, more preferably 50 mmol / L to 500 mmol / L, and can be determined depending on the type of dopant.

[0110] Next, an electrode made of a known conductive material such as stainless steel or platinum and a first electrode layer 141 having a solid electrolyte layer 163 formed on its outer surface via a dielectric layer 150 are immersed in a polymeric aqueous solution containing pyrrole and a dopant, and a predetermined voltage is applied across the solid electrolyte layer 163 for a predetermined time to grow a conductive polymer film 165 made of a polypyrrole film on the solid electrolyte layer 163. Thereafter, the conductive polymer film 165 made of a polypyrrole film may be washed. The polypyrrole film can be washed using, for example, water.

[0111] In this embodiment, the solid electrolyte layer 163, which is the precoat layer, is a polymer film containing a cross-linked polymer and PEDOT / PSS and has excellent water resistance. Therefore, when a polypyrrole film, which becomes the conductive polymer film 165, is formed using an electrolytic polymerization method, the precoat layer is less likely to dissolve. This allows for a stable electrolytic polymerization reaction, and the conductive polymer film 165, which is made of a polypyrrole film, is less likely to take on an island or mesh-like shape, allowing the solid electrolyte layer 163 to be sufficiently coated with the conductive polymer film 165. As a result, a solid electrolytic capacitor 100 with sufficient capacitance can be manufactured.

[0112] Next, a carbon layer 161 is formed on the outer surface of the conductive polymer film 165 made of polypyrrole. First, a carbon paste containing a carbon material and, if necessary, a binder resin and / or additives is prepared. Then, the carbon paste is applied to the outer surface of the conductive polymer film 165 made of polypyrrole by a known method, and dried to form the carbon layer 161.

[0113] Next, metal layer 162 is formed on the outer surface of carbon layer 161. When metal layer 162 is an Ag layer, it can be manufactured, for example, by the following method. A known Ag paste containing Ag particles and a binder resin is prepared. Then, the Ag paste is applied by a known method to the outer surface of conductive polymer film 165 on which carbon layer 161 has been formed, and then dried and cured.

[0114] In this embodiment, a plating method can be used as a method for manufacturing the metal layer 162. For example, when the metal layer 162 is a Cu layer, the Cu layer can be formed on the outer surface of the conductive polymer film 165 on which the carbon layer 161 is formed by electroless Cu plating.

[0115] Specifically, a seed paste containing a carbon material, polypyrrole particles, and a binder resin is prepared. The seed paste is then applied to the outer surface of the conductive polymer film 165 on which the carbon layer 161 is formed by a known method, and dried to form a seed layer. The conductive polymer film 165 on which the carbon layer 161 and seed layer are formed is then immersed in a plating solution, and electroless Cu plating is performed under known conditions. This results in the formation of a metal layer 162 made of a Cu layer. The plating solution used to form the Cu layer can be a known plating solution used in electroless Cu plating, or it may be an aqueous solution. By performing the above steps, multiple capacitor elements 170 are obtained.

[0116] Next, a plate-shaped first terminal piece that will become the first terminal 120 and a plate-shaped second terminal piece that will become the second terminal 130 are prepared and arranged in a straight line while being spaced apart from each other. Next, a plurality of capacitor elements 170 are stacked and arranged on the first terminal piece and the second terminal piece. At this time, the second electrode layer 160 of the plurality of capacitor elements 170 is placed on the first terminal piece, and the first electrode layer 141 is placed on the second terminal piece.

[0117] Then, on the second electrode layer 160 side, a conductive adhesive that will become the connecting conductor layer 190 is interposed between adjacent capacitor elements 170. Similarly, a conductive adhesive that will become the connecting conductor layer 190 is also interposed between a first terminal piece and an adjacent capacitor element 170. This allows the second electrode layers 160 of the multiple capacitor elements 170 to be electrically connected to the first terminal pieces by the connecting conductor layer 190. Thereafter, one ends of the first electrode layers 141 of the multiple capacitor elements 170 are electrically connected to the second terminal pieces using a method such as welding.

[0118] Next, the first terminal piece, the second terminal piece and the plurality of capacitor elements 170 are placed in a mold so that the end of the first terminal piece located opposite the second terminal piece and the end of the second terminal piece located opposite the first terminal piece are exposed, and a resin mold layer 110 is formed using an insulating resin material containing a resin such as epoxy resin and a filler such as silica.

[0119] Thereafter, the first terminal piece protruding outward from the resin mold layer 110, inside which the plurality of capacitor elements 170 are provided, is bent along the outer surface of the resin mold layer 110 to form the first terminal 120. The second terminal piece protruding outward from the resin mold layer 110 is bent along the outer surface of the resin mold layer 110 to form the second terminal 130. By performing the above steps, the solid electrolytic capacitor 100 of this embodiment is obtained.

[0120] In the solid electrolytic capacitor 100 of this embodiment, the solid electrolyte layer 163 included in the capacitor element 170 is composed of a polymer film including PEDOT / PSS and a crosslinked polymer in which a polymer having a carbonyl group is crosslinked with a crosslinking agent made of a dihydrazide compound, and the second electrode layer 160 includes a conductive polymer film 165. Therefore, the solid electrolyte layer 163 of the solid electrolytic capacitor 100 of this embodiment has good water resistance and can be used as a precoat layer that is resistant to dissolution in a polymerization aqueous solution when the conductive polymer film 165 in contact with the solid electrolyte layer 163 is formed by electrolytic polymerization. Therefore, in the solid electrolytic capacitor 100 of this embodiment, the conductive polymer film 165 included in the second electrode layer 160 can be stably formed by electrolytic polymerization using the solid electrolyte layer 163 as a precoat layer.

[0121] Second Embodiment In the solid electrolytic capacitor 100 of the first embodiment, the solid electrolyte layer 163 is made of a polymer film containing PEDOT / PSS and a crosslinked polymer in which a polymer having a carbonyl group is crosslinked with a crosslinking agent made of a dihydrazide compound. However, in the solid electrolytic capacitor of the second embodiment, the solid electrolyte layer 163 is made of a polymer film containing a crosslinked polymer in which a composite of polyethylenedioxythiophene and polystyrene sulfonic acid (PEDOT / PSS) and / or a sulfonic acid compound having a polyethylenedioxythiophene (PEDOT) skeleton is crosslinked with a crosslinking agent, and the crosslinking agent is -NH ２ The following will explain an example of a salt of an amine compound containing a total of four or more groups selected from the group consisting of —NH— and —NH— groups.

[0122] The solid electrolytic capacitor of the second embodiment differs from the solid electrolytic capacitor 100 of the first embodiment only in the polymer film that forms the solid electrolyte layer 163. Therefore, in the second embodiment, descriptions of the same components as in the first embodiment will be omitted. As in the first embodiment, the solid electrolyte layer 163 in the second embodiment is used as a precoat layer when the conductive polymer film 165 of the second electrode layer 160 is formed by electrolytic polymerization. The solid electrolyte layer 163 in the second embodiment is made of the polymer film shown below.

[0123] [Polymer Film] The solid electrolyte layer 163 in the solid electrolytic capacitor of the second embodiment is made of a polymer film containing a crosslinked polymer in which PEDOT / PSS represented by formula (1) and / or a sulfonic acid compound having a PEDOT skeleton represented by formula (6) is crosslinked with a crosslinking agent.

[0124] The crosslinked polymer contained in the polymer film of this embodiment has a three-dimensional network structure resulting from a crosslinked structure between PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton and a crosslinking agent, and has excellent water resistance. The crosslinked polymer contained in the polymer film of this embodiment may be of only one type or of two or more types.

[0125] The crosslinking agent in the polymer membrane of this embodiment is —NH２ The salt of the amine compound includes a salt of an amine compound containing a total of four or more groups selected from one or two types of groups selected from the group consisting of an —NH— group and an —NH— group. ２ group, and —NH— group, and contains a total of four or more groups of one or two kinds selected from the group consisting of —NH ２ group, four N resulting from -NH- groups ＋ Therefore, a crosslinked structure can be sufficiently formed between PEDOT and a composite of styrene sulfonic acid or polystyrene sulfonic acid. Examples of the salt of the amine compound include hydrochlorides, phosphates, sulfonates, perchlorates, and salt-forming compounds with organic sulfonic acids such as paratoluenesulfonic acid. Among these salts of the amine compound, hydrochlorides are preferred because they can be easily dispersed in water and have good reactivity.

[0126] Examples of such crosslinking agents include N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride, N,N'-bis(3-aminopropyl)-1,3-propanediamine tetrahydrochloride, and N,N'-bis(2-aminoethyl)-1,3-propanediamine tetrahydrochloride, which are represented by formula (8).

[0127]

[0128] Among the above crosslinking agents, it is preferable to use N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride represented by formula (8). N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride represented by formula (8) is a crosslinking agent that can be used to crosslink PEDOT / PSS and / or the sulfonic acid compound having a PEDOT skeleton. ３This is because N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride, represented by formula (8), has good reactivity with H and can form a crosslinked polymer with better water resistance. Furthermore, N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride, represented by formula (8), can be easily dispersed in water. Therefore, a method in which an aqueous solution of the crosslinking agent is applied to a water-soluble film made of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton, dissolves a portion of the film made of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton, thereby promoting the crosslinking reaction with PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton, is preferred. In this embodiment, only one crosslinking agent may be used to crosslink PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton, or two or more crosslinking agents may be used.

[0129] The polymer membrane of this embodiment contains the crosslinked polymer described above, and may further contain one or more other components as needed in addition to the crosslinked polymer. Examples of other components include known resins other than PEDOT / PSS and sulfonic acid compounds having a PEDOT skeleton, and surface tension modifiers. Examples of resins other than PEDOT / PSS and sulfonic acid compounds having a PEDOT skeleton that are preferably water-soluble or water-dispersible resins include sulfonated polyester resins. Examples of surface tension modifiers include low-molecular-weight additives such as glycerin and ethylene glycol.

[0130] The polymer membrane of this embodiment is -NH ２ The polymer film of the present embodiment includes a crosslinked polymer in which PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is crosslinked with a crosslinking agent containing a salt of an amine compound containing a total of four or more groups selected from one or two types of groups selected from the group consisting of —NH— groups and —NH— groups. As a result, the polymer film of the present embodiment has excellent electrical conductivity and heat resistance, as well as good water resistance.

[0131] Furthermore, the solid electrolyte layer 163 in this embodiment may be formed by laminating multiple layers of polymer films with different components. When the solid electrolyte layer 163 in this embodiment is formed by two or more polymer films, the crosslinking agents used as materials for the crosslinked polymers in the laminated multiple polymer films may be different from each other, or some or all of them may be the same, and it is preferable that all of them are the same. This is because the adhesion between the multiple polymer films is improved, making it easier to obtain a solid electrolyte layer 163 with even better water resistance.

[0132] Furthermore, when the solid electrolyte layer 163 of this embodiment is composed of two or more polymer films, it may have one or more polymer films that do not contain the above-mentioned crosslinked polymer, in addition to the polymer film of this embodiment containing a crosslinked polymer obtained by crosslinking PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton with a crosslinking agent. The polymer film that does not contain the above-mentioned crosslinked polymer may contain any resin component, and examples thereof include a non-crosslinked polymer film made of PEDOT / PSS and a non-crosslinked polymer film made of a sulfonic acid compound having a PEDOT skeleton.

[0133] In this embodiment, when the solid electrolyte layer 163 is made up of two or more polymer films and includes a polymer film that does not contain a crosslinked polymer in which PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is crosslinked, it is preferable that the polymer film that does not contain the crosslinked polymer be the first polymer film that is arranged closest to the dielectric layer 150.

[0134] When the first polymer film is made of a polymer film that does not contain the above-mentioned crosslinked polymer, the second electrode layer 160 side of the first polymer film has one or more layers of a polymer film containing a crosslinked polymer in which PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is crosslinked by a crosslinking agent.

[0135] (Method for Manufacturing Solid Electrolyte Layer (Polymer Membrane)) Next, a method for providing the solid electrolyte layer 163 made of the polymer membrane of this embodiment on the outer surface of the dielectric layer 150 will be described.

[0136] First, a resin dispersion consisting of an aqueous dispersion of PEDOT / PSS and / or an aqueous solution of a sulfonic acid compound having a PEDOT skeleton is prepared. The resin dispersion may be composed solely of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton and water. The resin dispersion may contain PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton, water, and one or more of the other components described above. Specifically, the resin dispersion may contain PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton, water, a sulfonated polyester resin, and / or a surface tension modifier.

[0137] Next, the resin dispersion is applied to the outer surface of the dielectric layer 150 excluding the end portion connected to the second terminal 130 (i.e., the area where the insulating resin layer 151 is not formed) to form a coating film. The method for applying the resin dispersion to the outer surface of the dielectric layer 150 can be the same as the method for applying the resin paint to the outer surface of the dielectric layer 150 in the first embodiment.

[0138] Next, the coating film formed on the outer surface of the dielectric layer 150 is dried to remove water from the coating film. This results in a resin film made of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton. Known methods for removing water from the coating film, such as heat treatment at a temperature of 80°C to 150°C, can be used, and the method can be appropriately determined depending on the concentration of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton in the resin dispersion, the thickness of the coating film, and the like.

[0139] In this embodiment, the process of applying a resin dispersion onto the outer surface of the dielectric layer 150 and drying the resulting coating to form a resin film made of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton may be performed only once or multiple times.

[0140] Next, an aqueous solution of a crosslinking agent is applied onto the resin film made of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton. This brings the PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton in the resin film into contact with the crosslinking agent, and the -SO of the PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is crosslinked. ３ H and N of the amine compound which is a crosslinking agent ＋ A cross-linking reaction is initiated.

[0141] The crosslinking agent aqueous solution preferably contains a crosslinker in the range of 0.01 mol% to 1 mol%, more preferably 0.03 mol% to 1 mol%. When the crosslinking agent content is 0.01 mol% or more, applying the crosslinking agent aqueous solution onto a resin film and removing the water from the crosslinking agent aqueous solution sufficiently achieves the effect of forming a crosslinked structure between the PEDOT / PSS and / or sulfonic acid compound having a PEDOT skeleton and the crosslinking agent. Therefore, when the crosslinking agent content is 0.01 mol% or more, a polymer film with better water resistance is likely to be obtained. Furthermore, when the crosslinking agent content is 1 mol% or less, the impact of the remaining crosslinking agent that does not form a crosslinked structure is reduced, which is preferable.

[0142] As a method for applying the aqueous solution of the crosslinking agent onto the resin film made of PEDOT / PSS and / or sulfonic acid compound having a PEDOT skeleton, a method similar to the method for applying the resin paint onto the outer surface of the dielectric layer 150 in the first embodiment can be used. Next, the aqueous solution of the crosslinking agent applied onto the resin film is dried to remove water from the aqueous solution of the crosslinking agent. This allows the PEDOT / PSS and / or sulfonic acid compound having a PEDOT skeleton in the resin film and the N-type amine compound which is the crosslinking agent to be bonded to the resin film. ＋ By carrying out the above steps, a solid electrolyte layer 163 is formed, which has a polymer membrane of this embodiment including a crosslinked polymer in which PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is crosslinked by a crosslinking agent.

[0143] As a method for removing water from the aqueous solution of the cross-linking agent applied onto the resin film, a known method such as heat treatment at a temperature of 80°C to 150°C can be used, and the method can be appropriately determined depending on the shape of the region where the resin film is formed in the dielectric layer 150 formed on the outer surface of the first electrode layer 141, the thickness of the coating film, etc.

[0144] In this embodiment, the crosslinking reaction is initiated by applying an aqueous solution of a crosslinking agent onto the resin film. This promotes the crosslinking reaction in the portion of the resin film close to the surface. As a result, it is presumed that the density of the crosslinked structure contained in the polymer film of this embodiment changes continuously or stepwise in the thickness direction, and is higher closer to the surface. As a result, the polymer film has particularly high water resistance at the surface, and the effect of improving the water resistance of the polymer film due to the presence of a crosslinked structure is effectively achieved.

[0145] Therefore, the polymer film of this embodiment can achieve sufficient water resistance even with a smaller number of crosslinked structures compared to a polymer film in which the density of crosslinked structures contained therein is approximately uniform, for example, produced by a method of applying an aqueous dispersion containing PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton and a crosslinking agent. Therefore, the polymer film of this embodiment can increase the content of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton in the polymer film, resulting in better electrical conductivity and heat resistance compared to a polymer film in which the density of crosslinked structures is approximately uniform and has equivalent water resistance.

[0146] The polymer film forming the solid electrolyte layer 163 of this embodiment may be produced by forming the above-described resin film, applying an aqueous solution of a crosslinking agent thereon, and removing the water from the aqueous solution of the crosslinking agent only once, or by repeating the above steps multiple times to form a polymer film having a predetermined thickness. In this embodiment, the polymer film obtained by removing the water from the aqueous solution of the crosslinking agent may be washed. The polymer film may be washed using, for example, water.

[0147] The polymer film of this embodiment has good water resistance, so that by repeating the above steps multiple times, a polymer film that is uniform, sufficiently thick, and has a high coverage is easily obtained. This is because, if the polymer film has good water resistance, even if a resin dispersion consisting of an aqueous dispersion of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is applied to the polymer film in the second or subsequent steps, the polymer film is unlikely to be eluted in the water contained in the resin dispersion.

[0148] On the other hand, if the water resistance of the polymer film is insufficient, for example, when a resin dispersion consisting of an aqueous dispersion of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is applied to the polymer film formed in the first step in the second step, the polymer film formed in the first step will be re-eluted, and part or all of the polymer film formed in the first step will fall off, resulting in the thickness of the polymer film formed in the second step being uneven or insufficient.

[0149] Furthermore, in the present embodiment, when the solid electrolyte layer 163 is formed by laminating two layers of polymer films having different components, and both of the two layers of polymer films contain a crosslinked polymer in which PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is crosslinked with a crosslinking agent, the solid electrolyte layer 163 can be manufactured, for example, by the method shown below.

[0150] First, the above-described method for manufacturing the solid electrolyte layer 163 consisting of one layer of polymer film is used to manufacture a first polymer film to be disposed on the dielectric layer 150 side. Then, a second polymer film is manufactured on the outer surface of the dielectric layer 150 on which the first polymer film has been formed, in the same manner as the first polymer film, using a resin dispersion liquid whose components are different from the resin dispersion liquid used in manufacturing the first polymer film.

[0151] When the solid electrolyte layer 163 of this embodiment is made up of two or more polymer films, and has a polymer film of this embodiment containing a crosslinked polymer in which PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is crosslinked by a crosslinking agent, and one or more polymer films not containing the above-mentioned crosslinked polymer, it can be manufactured, for example, by the method shown below.

[0152] First, a polymer film that does not contain the above-mentioned cross-linked polymer, such as a non-cross-linked polymer film made of PEDOT / PSS or a non-cross-linked polymer film made of a sulfonic acid compound having a PEDOT skeleton, is formed as a first polymer film on the dielectric layer 150.

[0153] When forming a non-crosslinked polymer film made of PEDOT / PSS or a non-crosslinked polymer film made of a sulfonic acid compound having a PEDOT skeleton as the first polymer film, a method similar to the method for forming a resin film made of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton can be used in the manufacturing method of the solid electrolyte layer 163 made of the above-mentioned single-layer polymer film.

[0154] Then, on the outer surface of the dielectric layer 150 on which the first polymer film made of a polymer film not containing the above-mentioned crosslinked polymer is formed, one or more layers of polymer film containing a crosslinked polymer in which PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is crosslinked by a crosslinking agent are produced using the method for producing the solid electrolyte layer 163 made of a single layer of polymer film described above.

[0155] As described above, the solid electrolyte layer 163 of the second embodiment is also made of manganese oxide (MnO ２ Therefore, the solid electrolytic capacitor of the second embodiment can be formed without a high-temperature heat treatment, unlike the case of forming a precoat layer made of manganese oxide (MnO ２ In comparison with the case where a precoat layer made of a metal oxide is formed, the degree of freedom in selecting materials for use in manufacturing a solid electrolytic capacitor is high.

[0156] In the solid electrolytic capacitor of the second embodiment, the solid electrolyte layer 163 included in the capacitor element 170 is formed by dissolving PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton in the form of —NH ２The second electrode layer 160 comprises a polymer film containing a crosslinked polymer crosslinked by a crosslinking agent containing a salt of an amine compound containing a total of four or more groups selected from the group consisting of ——— groups and —NH— groups, and the second electrode layer 160 includes a conductive polymer film 165. Therefore, in the solid electrolytic capacitor of the second embodiment, as in the first embodiment, the water resistance of the solid electrolyte layer 163 is good, and when the conductive polymer film 165 in contact with the solid electrolyte layer 163 is formed by electrolytic polymerization, the solid electrolyte layer 163 can be used as a precoat layer that is difficult to dissolve in an aqueous polymerization solution. Therefore, in the solid electrolytic capacitor of the second embodiment, the conductive polymer film 165 included in the second electrode layer 160 can be stably formed by electrolytic polymerization using the solid electrolyte layer 163 as a precoat layer.

[0157] [Third Embodiment] In the solid electrolytic capacitor of the third embodiment, similarly to the solid electrolytic capacitor of the second embodiment, the polymer film forming the solid electrolyte layer 163 includes a crosslinked polymer in which a composite of polyethylenedioxythiophene and polystyrene sulfonic acid (PEDOT / PSS) and / or a sulfonic acid compound having a polyethylenedioxythiophene (PEDOT) skeleton is crosslinked by a crosslinking agent. In the solid electrolytic capacitor of the second embodiment, the crosslinking agent is -NH ２ In the above description, the cross-linking agent is an amine compound salt containing a total of four or more groups selected from the group consisting of ——— groups, —NH— groups, and —NH— groups. However, the solid electrolytic capacitor of the third embodiment will be described below using an example in which the cross-linking agent is made of a metal salt containing a metal cation with a valence of two or more.

[0158] The solid electrolytic capacitor of the third embodiment differs from the solid electrolytic capacitors of the first and second embodiments only in the polymer film that forms the solid electrolyte layer 163. Therefore, in the third embodiment, descriptions of the same components as in the first and second embodiments will be omitted. As in the first and second embodiments, the solid electrolyte layer 163 in the third embodiment is used as a precoat layer when the conductive polymer film 165 of the second electrode layer 160 is formed by electrolytic polymerization. The solid electrolyte layer 163 in the third embodiment is made of the polymer film shown below.

[0159] [Polymer Film] The crosslinked polymer contained in the polymer film of the third embodiment, like the polymer film of the second embodiment, is a polymer film containing a crosslinked polymer in which PEDOT / PSS represented by formula (1) and / or a sulfonic acid compound having a PEDOT skeleton represented by formula (6) are crosslinked with a crosslinking agent. Therefore, like the polymer film of the second embodiment, the crosslinked polymer contained in the polymer film of the third embodiment has a three-dimensional network structure resulting from the crosslinked structure between PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton and the crosslinking agent, and has excellent water resistance. The crosslinked polymer contained in the polymer film of this embodiment may be only one type, or two or more types.

[0160] In the third embodiment, the cross-linking agent in the polymer film forming the solid electrolyte layer 163 is made of a metal salt containing a metal cation with a valence of 2 or more. Examples of such a cross-linking agent include calcium chloride, magnesium chloride, and strontium chloride.

[0161] Among the above, calcium chloride is preferably used as the crosslinking agent. Calcium chloride is easily available and has a -SO group contained in PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton. ３ This is because calcium chloride has good reactivity with H and can form a crosslinked polymer with better water resistance. Furthermore, calcium chloride can be easily dispersed in water. Therefore, a method of applying an aqueous solution of the crosslinking agent to a water-soluble resin film made of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is preferable, as it can dissolve part of the resin film and promote the crosslinking reaction with PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton. In the third embodiment, the crosslinking agent used to crosslink PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton may be one type or two or more types.

[0162] The polymer membrane of this embodiment contains the crosslinked polymer described above. In addition to the crosslinked polymer, it may also contain one or more other components as needed. Examples of other components include known resins other than PEDOT / PSS and sulfonic acid compounds having a PEDOT skeleton, and surface tension modifiers. Examples of resins other than PEDOT / PSS and sulfonic acid compounds having a PEDOT skeleton include water-soluble or water-dispersible resins, specifically sulfonated polyester resins. Examples of surface tension modifiers include low-molecular-weight additives such as glycerin and ethylene glycol. Furthermore, the solid electrolyte layer 163 of this embodiment may be formed by laminating multiple polymer membranes of different components.

[0163] The polymer film of this embodiment contains a crosslinked polymer in which PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is crosslinked with a crosslinking agent made of a metal salt containing a metal cation with a valence of 2 or more, thereby providing the polymer film of this embodiment with excellent electrical conductivity and heat resistance, as well as good water resistance.

[0164] (Method for Manufacturing Solid Electrolyte Layer (Polymer Membrane)) Next, a method for providing the solid electrolyte layer 163 made of the polymer membrane of this embodiment on the outer surface of the dielectric layer 150 will be described.

[0165] First, in the third embodiment, as in the second embodiment, a resin dispersion consisting of an aqueous dispersion of PEDOT / PSS and / or an aqueous solution of a sulfonic acid compound having a PEDOT skeleton is prepared, and using this, as in the second embodiment, a resin film consisting of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton is formed.

[0166] Next, an aqueous solution of a crosslinking agent is applied to the resin film thus obtained. In the third embodiment, a metal salt containing a metal cation with a valence of two or more is used as the crosslinking agent contained in the aqueous solution of the crosslinking agent instead of the amine compound used in the second embodiment. This brings the PEDOT / PSS and / or sulfonic acid compound having a PEDOT skeleton in the resin film into contact with the crosslinking agent, initiating a crosslinking reaction between the PEDOT / PSS and / or sulfonic acid compound having a PEDOT skeleton and the metal cation contained in the metal salt serving as the crosslinking agent.

[0167] The crosslinking agent aqueous solution preferably contains a crosslinker in the range of 0.01 mol% to 2 mol%, more preferably 0.1 mol% to 1 mol%. When the crosslinking agent content is 0.01 mol% or more, applying the crosslinking agent aqueous solution onto a resin film and removing the water from the crosslinking agent aqueous solution results in the formation of a crosslinked structure between the PEDOT / PSS and / or sulfonic acid compound having a PEDOT skeleton and the crosslinking agent. Therefore, when the crosslinking agent content is 0.01 mol% or more, a polymer film with better water resistance is likely to be obtained. Furthermore, when the crosslinking agent content is 2 mol% or less, the impact of the remaining crosslinking agent that does not form a crosslinked structure is reduced, which is preferable.

[0168] The method for applying the aqueous solution of the crosslinking agent to the resin film made of PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton can be the same as the method for applying the resin paint to the outer surface of the dielectric layer 150 in the first embodiment. Next, the aqueous solution of the crosslinking agent applied to the resin film is dried to remove the water in the aqueous solution of the crosslinking agent. This further promotes the crosslinking reaction between the PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton in the resin film and the metal cation with a valence of two or more contained in the metal salt serving as the crosslinking agent. By performing the above steps, the solid electrolyte layer 163 of this embodiment is formed, which includes a crosslinked polymer formed by crosslinking PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton with the crosslinking agent.

[0169] As a method for removing water from the aqueous solution of the cross-linking agent applied onto the resin film, a known method such as heat treatment at a temperature of 80°C to 150°C can be used, and the method can be appropriately determined depending on the shape of the region where the resin film is formed in the dielectric layer 150 formed on the outer surface of the first electrode layer 141, the thickness of the coating film, etc.

[0170] In this embodiment, as in the second embodiment, the crosslinking reaction is initiated by applying an aqueous solution of a crosslinking agent onto the resin film. This promotes the crosslinking reaction in the portion of the resin film close to the surface. As a result, the polymer film of this embodiment is presumed to have a density of the crosslinked structure contained in the polymer film that varies continuously or stepwise in the thickness direction, with the density increasing the closer to the surface. As a result, the polymer film has particularly high water resistance at the surface, and the effect of improving the water resistance of the polymer film due to the presence of a crosslinked structure is effectively achieved.

[0171] The polymer film forming the solid electrolyte layer 163 of this embodiment may be produced by forming the above-described resin film, applying an aqueous solution of a crosslinking agent thereon, and removing the water from the aqueous solution of the crosslinking agent only once, or by repeating the above steps multiple times to form a polymer film having a predetermined thickness. In this embodiment, the polymer film obtained by removing the water from the aqueous solution of the crosslinking agent may be washed. The polymer film may be washed using, for example, water.

[0172] In the solid electrolytic capacitor of the second embodiment, the cross-linking agent is —NH ２ In the solid electrolytic capacitor of the third embodiment, the cross-linking agent is a metal salt containing a metal cation having a valence of two or more. In the second or third embodiment, when the solid electrolyte layer 163 is composed of two or more polymer films, the solid electrolyte layer 163 may have a polymer film containing the above-mentioned salt of the amine compound as a cross-linking agent, and a polymer film containing the above-mentioned metal salt containing a metal cation having a valence of two or more.

[0173] As described above, the solid electrolyte layer 163 of the third embodiment is also made of manganese oxide (MnO ２ Therefore, the solid electrolytic capacitor of the third embodiment can be formed without a high-temperature heat treatment, unlike the case of forming a precoat layer made of manganese oxide (MnO ２ In comparison with the case where a precoat layer made of a metal oxide is formed, the degree of freedom in selecting materials for use in manufacturing a solid electrolytic capacitor is high.

[0174] In the solid electrolytic capacitor of the third embodiment, the solid electrolyte layer 163 included in the capacitor element 170 is a polymer film including a crosslinked polymer formed by crosslinking PEDOT / PSS and / or a sulfonic acid compound having a PEDOT skeleton with a crosslinking agent made of a metal salt containing a metal cation with a valence of two or more, and the second electrode layer 160 includes a conductive polymer film 165. Therefore, in the solid electrolytic capacitor of the third embodiment, as in the first and second embodiments, the solid electrolyte layer 163 has good water resistance, and when the conductive polymer film 165 in contact with the solid electrolyte layer 163 is formed by electrolytic polymerization, the solid electrolyte layer 163 can be used as a precoat layer that is not easily dissolved in a polymerization aqueous solution. Therefore, in the solid electrolytic capacitor of the third embodiment, the conductive polymer film 165 included in the second electrode layer 160 can be stably formed by electrolytic polymerization using the solid electrolyte layer 163 as a precoat layer.

[0175] 4 is a schematic cross-sectional view of a solid electrolytic capacitor according to a fourth embodiment of the present invention. The solid electrolytic capacitor 200 shown in FIG. 4 includes a resin molded layer 11 having a substantially rectangular parallelepiped outer shape, a capacitor element provided inside the resin molded layer 11, a first terminal 12, and a second terminal 13.

[0176] The resin mold layer 11 forms the exterior of the solid electrolytic capacitor 200, and may be the same as the resin mold layer 110 in the solid electrolytic capacitor 100 of the first embodiment.

[0177] The first terminal 12 is made of a conductive material such as Cu. The first terminal 12 is electrically connected to the second electrode layer 16 of the capacitor element by a connecting conductor layer 19 and is extended to the outside of the resin molded layer 11. The connecting conductor layer 19 may be made of, for example, a conductive adhesive containing Ag. The portion of the first terminal 12 located inside the resin molded layer 11 is bent to conform to the outer shape of the first electrode layer 14, which is a substantially rectangular block. The portion of the first terminal 12 located outside the resin molded layer 11 is bent to conform to the outer surface of the resin molded layer 11.

[0178] The second terminal 13 is made of a conductive material such as Cu. The second terminal 13 is electrically connected to the first electrode layer 14 of the capacitor element via a lead 41 and is extended to the outside of the resin mold layer 11. The portion of the second terminal 13 located outside the resin mold layer 11 is bent along the outer surface of the resin mold layer 11.

[0179] As shown in Fig. 4, the end of the lead 41 on the first electrode layer 14 side is embedded in the first electrode layer 14. The end of the lead 41 on the first electrode layer 14 side extends from approximately the center of one of the outer surfaces of the approximately rectangular parallelepiped first electrode layer 14 toward approximately the center of the first electrode layer 14. As shown in Fig. 4, the end of the lead 41 on the second terminal 13 side penetrates the solid electrolyte layer 63 and the second electrode layer 16 while being covered with the dielectric layer 15. The dielectric layer 15 is not formed on the surface of the end of the lead 41 on the second terminal 13 side, and the end is electrically connected to the second terminal 13 by resistance welding or the like.

[0180] The lead 41 can be made of a conductive material such as aluminum, tantalum, or niobium. The lead 41 is preferably made of the same material as the first electrode layer 14. The reason for this is that the dielectric layer 15 can be formed on the outer surface of the first electrode layer 14 and on the surfaces of the fine holes in the first electrode layer 14, and at the same time, the dielectric layer 15 can be formed on the surface of the lead 41 exposed from the first electrode layer 14, thereby enabling efficient manufacturing.

[0181] (First Electrode Layer 14) The first electrode layer 14 functions as an anode in the solid electrolytic capacitor 200. The first electrode layer 14 is a sintered body of a valve metal or a metal containing a valve metal as a main component, and is made of a porous body having a large number of fine pores (not shown) that communicate from the inside to the outside.

[0182] Examples of valve metals used as the material for the first electrode layer 14 include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Among the above valve metals, it is preferable to use one or more selected from aluminum, tantalum, and niobium as the material for the first electrode layer 14, and tantalum and / or niobium are more preferable. This is because the dielectric layer 15 can be stably formed by anodizing the outer surface of the first electrode layer 14 and the surfaces of the fine pores in the first electrode layer 14.

[0183] 4, the dielectric layer 15 is formed along the outer surface of the first electrode layer 14 so as to cover the first electrode layer 14. The dielectric layer 15 is also formed on the surfaces of minute holes in the first electrode layer 14. The dielectric layer 15 is also formed on the surface of the lead 41 exposed from the first electrode layer 14, excluding the end of the lead 41 on the second terminal 13 side.

[0184] The dielectric layer 15 is made of an electrically insulating metal oxide film. For example, when the first electrode layer 14 is a sintered body of tantalum, the dielectric layer 15 is preferably made of a tantalum oxide film. The thickness of the dielectric layer 15 is usually 1 nm to 1 μm.

[0185] (Solid Electrolyte Layer 63) As shown in Fig. 4, the solid electrolyte layer 63 is formed along the outer surface of the dielectric layer 15. The solid electrolyte layer 63 in this embodiment may be a polymer film similar to the polymer film that can be used as the solid electrolyte layer 163 in the solid electrolytic capacitor of any of the first to third embodiments. The solid electrolyte layer 63 in this embodiment, like the solid electrolyte layer 163 in the first to third embodiments, is used as a precoat layer when the conductive polymer film 60 of the second electrode layer 16 is formed by electrolytic polymerization.

[0186] 4 , the second electrode layer 16 formed on the outer surface of the solid electrolyte layer 63 is composed of a conductive polymer film 60, a carbon layer 61 formed on the outer surface of the conductive polymer film 60, and a metal layer 62 formed on the outer surface of the carbon layer 61. In this embodiment, the second electrode layer 16 is described as being composed of three layers, namely, the conductive polymer film 60, the carbon layer 61, and the metal layer 62. However, the second electrode layer may have a single-layer structure composed of only the conductive polymer film 60, or a multi-layer structure of four or more layers composed of the conductive polymer film 60 and multiple carbon layers 61 and / or metal layers 62.

[0187] The conductive polymer film 60 is formed by electrolytic polymerization using the solid electrolyte layer 63 as a precoat layer, similar to the conductive polymer film 165 in the solid electrolytic capacitor 100 of the first embodiment. The conductive polymer film 60, carbon layer 61, and metal layer 62 of the second electrode layer 16 in this embodiment may be the same as the conductive polymer film 165, carbon layer 161, and metal layer 162 of the second electrode layer 160 in the solid electrolytic capacitor 100 of the first embodiment, respectively.

[0188] (Method of Manufacturing Solid Electrolytic Capacitor) The solid electrolytic capacitor 200 of this embodiment can be manufactured, for example, by the following method. First, a block-shaped first electrode layer 14 is prepared, which is a sintered body of a valve metal such as tantalum or a metal containing a valve metal as its main component. The first electrode layer 14 can be formed by molding powder containing a metal containing a valve metal as its main component into a compact using a known method, and then sintering the compact using a known method. Next, one end of a lead 41 is embedded in one of the outer surfaces of the approximately rectangular parallelepiped first electrode layer 14 from approximately the center toward the center of the first electrode layer 14 using a known method, thereby integrating the first electrode layer 14 and the lead 41.

[0189] (Dielectric Layer Forming Process) Next, a dielectric layer 15 is provided on the outer surface of the first electrode layer 14, the surfaces of the fine holes in the first electrode layer 14, and the surfaces of the leads 41 exposed from the first electrode layer 14. For example, if the first electrode layer 14 is a sintered body made of tantalum and the leads 41 are made of tantalum, the dielectric layer 15 made of a tantalum oxide film can be formed by an anodizing method using ammonium acetate, sulfuric acid, phosphoric acid, or the like as a chemical conversion treatment solution (electrolyte).

[0190] (Solid electrolyte layer forming process) (Second electrode layer forming process) Next, a solid electrolyte layer 63 made of a polymer film is provided on the outer surface of the dielectric layer 15 by the same method as when providing the solid electrolyte layer 163 in the solid electrolytic capacitor of any of the first to third embodiments.

[0191] (Second Electrode Layer Forming Process) Thereafter, a conductive polymer film 60 in contact with the solid electrolyte layer 63 is formed on the outer surface of the solid electrolyte layer 63 by electrolytic polymerization in the same manner as when providing the conductive polymer film 165 in the solid electrolytic capacitor of any of the first to third embodiments. Thereafter, a carbon layer 61 and a metal layer 62 are formed in this order on the outer surface of the conductive polymer film 60 in the same manner as in the solid electrolytic capacitor of any of the first to third embodiments, thereby forming the second electrode layer 16.

[0192] Next, the metal layer 62 of the second electrode layer 16 and a plate-shaped first terminal piece that will become the first terminal 12 are electrically connected by the connecting conductor layer 19. Also, the end of the lead 41 that is not embedded in the first electrode layer 14 is electrically connected to a plate-shaped second terminal piece that will become the second terminal 13. Thereafter, in the same manner as the resin mold layer 110 of the solid electrolytic capacitor 100 of the first embodiment, a resin mold layer 11 is formed from an insulating resin material that contains a resin such as an epoxy resin and a filler such as silica.

[0193] Thereafter, the first terminal piece protruding outward from the resin mold layer 11 is bent along the outer surface of the resin mold layer 11 to form the first terminal 12. Furthermore, the second terminal piece protruding outward from the resin mold layer 11 is bent along the outer surface of the resin mold layer 11 to form the second terminal 13. By performing the above steps, the solid electrolytic capacitor 200 of this embodiment is obtained.

[0194] In the solid electrolytic capacitor 200 of the fourth embodiment, the solid electrolyte layer 63 included in the capacitor element is made of a polymer film that can be used for the solid electrolyte layer 163 of the solid electrolytic capacitor of any of the first to third embodiments, and the second electrode layer 16 includes a conductive polymer film 60. Therefore, the solid electrolyte layer 63 of the solid electrolytic capacitor 200 of the fourth embodiment has good water resistance and can be used as a precoat layer that is difficult to dissolve in a polymerization aqueous solution when the conductive polymer film 60 in contact with the solid electrolyte layer 63 is formed by electrolytic polymerization. Therefore, in the solid electrolytic capacitor 200 of the fourth embodiment, the conductive polymer film 60 included in the second electrode layer 16 can be stably formed by electrolytic polymerization using the solid electrolyte layer 63 as a precoat layer.

[0195] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0196] (Example 1) A strip-shaped aluminum foil having a width of 3.5 mm was prepared, and both the front and back surfaces were subjected to a roughening treatment. Then, a resist layer was formed in the longitudinal center of both the front and back surfaces of the aluminum foil. As a result, an electrode formation region consisting of aluminum foil having a width of 3.5 mm and a length of 4.7 mm was defined at one end of the region where the resist layer was not formed, which was present at both ends of the aluminum foil.

[0197] Next, the electrode formation region of the aluminum foil was immersed in a 15% aqueous solution of ammonium adipate. Subsequently, an anodization treatment was performed in which the aluminum foil was used as a positive electrode and the negative electrode was immersed in an aqueous solution of ammonium adipate and a voltage was applied, thereby forming an aluminum oxide film on the outer surface of the aluminum foil in the electrode formation region. Thereafter, the aluminum oxide film was washed with running water and dried by heat treatment at 80°C.

[0198] Next, PEDOT / PSS represented by formula (1) (n in formula (1)) １ is 2 to 10, and m １ The average polymerization degree n in the formula (2) was 2 to 10. ２ +m ２ The molecular weight was 500. R was a methyl group. The degree of saponification was 95% to 99%. A 5% by mass aqueous solution of PEDOT / PSS was mixed with the resulting mixture. The aqueous dispersion of PEDOT / PSS consisted of PEDOT / PSS and water alone. A 5% by mass aqueous solution of adipic acid dihydrazide represented by formula (3), which serves as a crosslinking agent, was mixed with the resulting mixture and stirred to obtain a resin coating material.

[0199] As shown in Table 1, the content of PEDOT / PSS and modified polyvinyl alcohol in the resin coating was set to a solid mass ratio of 55% by mass:45% by mass (PEDOT / PSS:modified polyvinyl alcohol). The content of the crosslinking agent in the resin coating was set to 5% by mass relative to the mass of the solid mass of the modified polyvinyl alcohol.

[0200] Next, the electrode formation region of the aluminum foil on which the aluminum oxide film was formed was immersed in the resin paint prepared by the method described above and then pulled out, thereby applying the resin paint to the electrode formation region, and the formed coating film was dried by heat treatment at 120° C. Thereafter, the operation of applying the resin paint to the electrode formation region of the aluminum foil and drying it was repeated twice, thereby obtaining a solid electrolyte layer of Example 1 consisting of a first polymer film.

[0201] (Examples 2 and 3) Solid electrolyte layers of Examples 2 and 3 made of a first polymer membrane were obtained in the same manner as in Example 1, except that the contents of PEDOT / PSS and modified polyvinyl alcohol (PVA) contained in the resin coating were set to the contents shown in Table 1, respectively, in terms of mass ratio of solid content.

[0202] (Example 4) Modified polyvinyl alcohol (PVA) represented by formula (2) (n in formula (2) represents the average degree of polymerization) ２ +m ２ The average polymerization degree n in formula (2) was 500. R was a methyl group. The saponification degree was 95% to 99%. ２ +m ２ The molecular weight of the solid electrolyte layer of Example 4 was 2000. R was a methyl group. The degree of saponification was 95% to 99%. A solid electrolyte layer of Example 4 made of a first polymer membrane was obtained in the same manner as in Example 2, except that a 5 mass % aqueous solution of

[0203] (Example 5) The electrode formation region of the aluminum foil on which the aluminum oxide film was formed was immersed in an aqueous dispersion (resin dispersion) of PEDOT / PSS used as the resin coating material in Example 1 and then pulled out, thereby applying the resin dispersion to the electrode formation region, and the formed coating film was dried by heat treatment at 120° C. Thereafter, the operation of applying the resin dispersion to the electrode formation region of the aluminum foil and drying was repeated twice to form a resin film.

[0204] Next, the electrode formation region on which the resin film was formed was immersed in an aqueous solution of a crosslinking agent containing 0.1 mol % of N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride represented by formula (8) and then pulled out, thereby coating the electrode formation region with the aqueous solution of the crosslinking agent, and the formed coating film was dried by heat treatment at 120°C, thereby obtaining a solid electrolyte layer of Example 5 made of a first polymer film.

[0205] Example 6 A solid electrolyte layer of Example 6 made of a first polymer membrane was obtained in the same manner as in Example 5, except that an aqueous solution of a crosslinking agent containing 0.1 mol % of calcium chloride was used instead of the aqueous solution of a crosslinking agent containing 0.1 mol % of N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride represented by formula (8).

[0206] Example 7 Instead of the aqueous dispersion of PEDOT / PSS (resin dispersion) used as the material of the resin coating in Example 1, a sulfonic acid compound having a PEDOT skeleton represented by formula (6) (n in formula (6)) was used. ３ was 2 to 10. ３ is (-CH ２ -)r (where r is 1 to 6). X ３ were hydrogen atoms.) was used. The resin dispersion was applied to the electrode formation region of the aluminum foil on which the aluminum oxide film was formed, and the formed coating film was dried by heat treatment at 120°C in the same manner as in Example 5. Thereafter, the resin dispersion was again applied to the electrode formation region of the aluminum foil, and the operation of drying was repeated to form a resin film.

[0207] Next, in the same manner as in Example 5, the electrode formation region on which the resin film was formed was immersed in an aqueous solution of a crosslinking agent containing 0.1 mol % of N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride represented by formula (8) and then pulled out, thereby coating the electrode formation region with the aqueous solution of the crosslinking agent, and the formed coating film was dried by heat treatment at 120°C, thereby obtaining a solid electrolyte layer of Example 7 consisting of a first polymer film.

[0208] Example 8 A resin film was formed as a first polymer film on the electrode formation region of the aluminum foil where the aluminum oxide film was formed, in the same manner as in Example 7. Thereafter, the first polymer film in Example 1 was formed as a second polymer film on the electrode formation region where the first polymer film was formed, in the same manner as in Example 1, to obtain a solid electrolyte layer of Example 8.

[0209] Example 9 A first polymer film was formed in the same manner as in Example 8. Thereafter, the first polymer film in Example 2 was formed as a second polymer film in the electrode formation region where the first polymer film was formed in the same manner as in Example 2, thereby obtaining a solid electrolyte layer of Example 9.

[0210] Example 10 A first polymer film was formed in the same manner as in Example 8. Thereafter, a resin paint was applied to the electrode formation region on which the first polymer film had been formed in the same manner as in Example 1, except that the contents of PEDOT / PSS and modified polyvinyl alcohol contained in the resin paint in Example 1 were set to a mass ratio of 85 mass %:15 mass % (PEDOT / PSS:modified polyvinyl alcohol) in terms of solid content, and the formed coating film was dried by heat treatment at 120°C to form a second polymer film, thereby obtaining a solid electrolyte layer of Example 10.

[0211] Example 11 A first polymer film was formed in the same manner as in Example 8. Thereafter, the electrode formation region on which the first polymer film was formed was immersed in an aqueous dispersion (resin dispersion) of PEDOT / PSS used as the material for the resin coating in Example 1 and then pulled out, thereby applying the resin dispersion to the electrode formation region, and the formed coating film was dried by heat treatment at 120°C to form a resin film.

[0212] Next, in the same manner as in Example 5, the electrode formation region on which the resin film was formed was immersed in an aqueous solution of a crosslinking agent containing 0.1 mol % of N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride represented by formula (8) and then pulled out, thereby coating the electrode formation region with the aqueous solution of the crosslinking agent, and the formed coating film was dried by heat treatment at 120°C to form a second polymer, thereby obtaining the solid electrolyte layer of Example 11.

[0213] Comparative Example 1 Instead of the aqueous dispersion of PEDOT / PSS (resin dispersion) used as the material for the resin coating in Example 1, a sulfonic acid compound having a PEDOT skeleton represented by formula (6) (n in formula (6)) was used. ３ was 2 to 10. ３ is (-CH ２ -)r (where r is 1 to 6). X ３ The resin dispersion was applied to the electrode formation region of the aluminum foil on which the aluminum oxide film was formed, in the same manner as in Example 5, except that a 2 mass % aqueous dispersion (resin dispersion) of 2,2'-dimethylamino-3,2'-triazol-2,2'-di ...

[0214] Comparative Example 2 A first polymer film was formed in the same manner as in Example 8. Thereafter, the first polymer film in Comparative Example 1 was formed as a second polymer film in the electrode formation region where the first polymer film had been formed in the same manner as in Comparative Example 1, thereby obtaining a solid electrolyte layer of Comparative Example 2.

[0215] Comparative Example 3 A first polymer membrane was formed in the same manner as in Example 8, and a solid electrolyte layer of Comparative Example 3 was obtained.

[0216] The types [A] and [B] of resin dispersions, the types [a] and [b] of modified PVAs, and the types [I], [II], and [III] of crosslinking agents shown in Table 1 are as follows:

[0217] (Types of Resin Dispersions) [A] A sulfonic acid compound having a PEDOT skeleton represented by formula (6) (n ３ was 2 to 10. ３ is (-CH ２ -)r (where r is 1 to 6). X ３ was a hydrogen atom.) and an aqueous solution consisting of only water and containing 2% by mass of a sulfonic acid compound having a PEDOT skeleton. [B] PEDOT / PSS represented by formula (1) (n in formula (1) １ is 2 to 10, and m １ was 2 to 10.) and an aqueous dispersion consisting of water only and containing 2% by mass of PEDOT / PSS.

[0218] (Type of modified PVA) [a] Modified polyvinyl alcohol represented by formula (2) (n ２ +m ２ The average polymerization degree in the formula (2) was 500. R was a methyl group. The degree of saponification was 95% to 99%. [b] An aqueous solution containing 5% by mass of a modified polyvinyl alcohol represented by the formula (2) (n ２ +m ２ The viscosity was 2000. R was a methyl group. The degree of saponification was 95% to 99%.

[0219] (Types of crosslinking agents) [I] An aqueous solution containing 5 mass % of adipic acid dihydrazide represented by formula (3). [II] An aqueous solution containing 0.1 mol % of N,N'-bis(3-aminopropyl)-1,4-butanediamine tetrahydrochloride represented by formula (8). [III] An aqueous solution of a crosslinking agent containing 0.1 mol % of calcium chloride.

[0220]

[0221] On the outer surface of the solid electrolyte layer thus obtained in Examples 1 to 11 and Comparative Examples 1 to 3, a conductive polymer film made of a polypyrrole film was formed by electrolytic polymerization using the solid electrolyte layer as a precoat layer by the method described below. First, an aqueous polymerization solution containing pyrrole and a dopant made of alkylnaphthalenesulfonic acid represented by formula (7) (trade name: sodium alkylnaphthalenesulfonate, manufactured by Tokyo Chemical Industry Co., Ltd.) was prepared. The content of pyrrole in the aqueous polymerization solution was 100 mmol / L. The content of the dopant in the aqueous polymerization solution was 50 mmol / L. The dopant was a compound represented by the formula (7) R ４ is a sodium atom, and R ４ A mixture containing those in which is a hydrogen atom was used.

[0222] Next, a stainless steel electrode and an aluminum foil having an aluminum oxide film and a solid electrolyte layer formed on its outer surface were immersed in a polymerization aqueous solution containing pyrrole and a dopant. A voltage of 2 V was then applied for 30 minutes to carry out an electrolytic polymerization reaction, growing a polypyrrole (PPy) film with an average thickness of 5 μm or more on the solid electrolyte layer. The grown polypyrrole film was then washed with water and dried by heat treatment at 80°C.

[0223] The polypyrrole films thus obtained in Examples 1 to 11 and Comparative Examples 1 to 3 were observed and evaluated for their state of formation by the method described below. "State of Formation of Polypyrrole Film" The state of formation of the polypyrrole film was visually observed, and if the entire surface of the portion of the aluminum foil immersed in the aqueous polymerization solution was covered with a polypyrrole film, it was determined that an electrolytically polymerized film had been formed. Furthermore, if only a portion of the surface of the portion of the aluminum foil immersed in the aqueous polymerization solution was covered with a polypyrrole film, it was determined that an electrolytically polymerized film had not been formed. Then, those determined not to have formed an electrolytically polymerized film are indicated in Table 1 as "electrolytically polymerized film not formed."

[0224] Next, a carbon paste containing a carbon material and a binder resin was applied to the outer surface of the conductive polymer film made of polypyrrole film of Examples 1 to 11 and Comparative Examples 1 to 3 obtained in this manner, and dried to form a carbon layer with a thickness of 2 μm. Furthermore, an Ag paste containing Ag particles and a binder resin was applied to the carbon layer, and dried and cured to form a metal layer made of an Ag layer with a thickness of 10 μm. By performing the above steps, the capacitor elements of Examples 1 to 11 and Comparative Examples 1 to 3 were obtained.

[0225] Furthermore, among the capacitor elements of Examples 1 to 11 and Comparative Examples 1 to 3, the state of formation of the polypyrrole film was observed, and for those capacitor elements of Examples 1 to 11 in which it was determined that an electrolytically polymerized film had been formed, the capacitance appearance rate was determined by the method described below. [Capacitance Appearance Rate] The capacitance of the capacitor element was measured at a frequency of 120 Hz using an LCR meter (product name: 4284A, manufactured by Hewlett-Packard Co.), and the capacitance appearance rate relative to the theoretical capacitance of the Al foil was calculated. The results are shown in Table 1.

[0226] As shown in Table 1, in the capacitor elements of Comparative Examples 1 to 3 having a solid electrolyte layer made of PEDOT / PSS represented by formula (1) and / or a sulfonic acid compound having a PEDOT skeleton represented by formula (6), a conductive polymer film made of a polypyrrole film with sufficient performance was not formed.

[0227] The reason for this is that in the capacitor elements of Comparative Examples 1 to 3, when a polypyrrole film was formed by electrolytic polymerization, the solid electrolyte layer, which was a precoat layer, dissolved in the aqueous polymerization solution containing pyrrole and a dopant, making the electrolytic polymerization reaction unstable. As a result, in the capacitor elements of Comparative Examples 1 to 3, the polypyrrole film functioning as an electrode assumed an island or mesh shape, and it is presumed that an electrolytic polymerization film was not formed.

[0228] In contrast, as shown in Table 1, the capacitor elements of Examples 1 to 11 had electrolytically polymerized films formed thereon, and sufficient capacitance was obtained. This is because the solid electrolyte layer used as a precoat layer when forming the polypyrrole film using electrolytic polymerization in the capacitor elements of Examples 1 to 11 is a polymer film with good water resistance. As a result, it is presumed that the polypyrrole film functioning as an electrode formed using electrolytic polymerization in the capacitor elements of Examples 1 to 11 was formed so as to sufficiently cover the solid electrolyte layer without forming an island or mesh-like structure.

[0229] Furthermore, as shown in Table 1, when the capacitor elements of Example 1 and Example 8, the capacitor elements of Example 2 and Example 9, and the capacitor elements of Example 3 and Example 10 are compared, the capacitance of the capacitor elements of Examples 8 to 10 is higher. This is presumably because the sulfonic acid compound having a PEDOT skeleton represented by formula (6) forming the first polymer film in Examples 8 to 10 has a smaller molecular weight than the PEDOT / PSS represented by formula (1) forming the first polymer film in Examples 1 to 3, and therefore easily penetrates into the minute recesses present on the outer surface of the aluminum oxide film, resulting in a high coverage of the surface of the dielectric layer with the first polymer film.

[0230] The solid electrolytic capacitor of this embodiment is widely used in various electronic devices.

[0231] 100, 200 solid electrolytic capacitor, 11, 110 resin mold layer, 12, 120 first terminal, 13, 130 second terminal, 14, 141 first electrode layer, 15, 150 dielectric layer, 41 lead, 151 insulating resin layer, 16, 160 second electrode layer, 60, 165 conductive polymer film, 61, 161 carbon layer, 62, 162 metal layer, 63, 163 solid electrolyte layer, 170 capacitor element, 19, 190 connecting conductor layer.

Claims

1. A solid electrolytic capacitor comprising: a capacitor element having: a first electrode layer; a dielectric layer formed on the outer surface of the first electrode layer; a solid electrolyte layer formed on the outer surface of the dielectric layer; and a second electrode layer formed on the outer surface of the solid electrolyte layer; wherein the solid electrolyte layer is made of a polymer film containing a crosslinked polymer formed by crosslinking a polymer having a carbonyl group with a crosslinking agent made of a dihydrazide compound, and a composite of polyethylenedioxythiophene and polystyrenesulfonic acid; the second electrode layer has a conductive polymer film formed in contact with the solid electrolyte layer; and the solid electrolyte layer is a precoat layer used when forming the conductive polymer film by electrolytic polymerization.

2. The solid electrolytic capacitor according to claim 1, wherein the polymer having a carbonyl group has a polyvinyl alcohol skeleton.

3. The solid electrolytic capacitor according to claim 1, wherein the ratio of the structural units derived from the polymer having a carbonyl group to the total mass of the structural units derived from the polymer having a carbonyl group forming the crosslinked polymer and the composite is 70 mass% or less, and the ratio of the structural units derived from the crosslinking agent to the mass of the structural units derived from the polymer having a carbonyl group is 15 mass% or less.

4. The solid electrolytic capacitor according to claim 1, wherein the ratio of the structural units derived from the polymer having a carbonyl group to the total mass of the structural units derived from the polymer having a carbonyl group forming the crosslinked polymer and the composite is 30 mass% or less, and the ratio of the structural units derived from the crosslinking agent to the mass of the structural units derived from the polymer having a carbonyl group is 10 mass% or less.

5. A capacitor element comprising: a first electrode layer; a dielectric layer formed on the outer surface of the first electrode layer; a solid electrolyte layer formed on the outer surface of the dielectric layer; and a second electrode layer formed on the outer surface of the solid electrolyte layer, wherein the solid electrolyte layer is a polymer film containing a crosslinked polymer formed by crosslinking a composite of polyethylenedioxythiophene and polystyrene sulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton with a crosslinking agent, and the crosslinking agent is a -NH ２ a salt of an amine compound containing a total of four or more groups selected from one or two types of groups selected from the group consisting of an —NH— group and an —NH— group, wherein the second electrode layer has a conductive polymer film formed in contact with the solid electrolyte layer, and the solid electrolyte layer is a precoat layer used when forming the conductive polymer film by electrolytic polymerization.

6. A solid electrolytic capacitor comprising: a capacitor element having: a first electrode layer; a dielectric layer formed on the outer surface of the first electrode layer; a solid electrolyte layer formed on the outer surface of the dielectric layer; and a second electrode layer formed on the outer surface of the solid electrolyte layer, wherein the solid electrolyte layer is a polymer film containing a crosslinked polymer formed by crosslinking a composite of polyethylenedioxythiophene and polystyrene sulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton with a crosslinking agent, and the crosslinking agent is a metal salt containing a metal cation having a valence of two or more; the second electrode layer has a conductive polymer film formed in contact with the solid electrolyte layer; and the solid electrolyte layer is a precoat layer used when forming the conductive polymer film by electrolytic polymerization.

7. The solid electrolytic capacitor according to claim 6, wherein the cross-linking agent is calcium chloride.

8. The solid electrolytic capacitor according to any one of claims 1 to 7, wherein the conductive polymer film is made of a polymer having a pyrrole skeleton.

9. The solid electrolytic capacitor according to any one of claims 1 to 7, wherein the first electrode layer is made of aluminum foil.

10. The solid electrolytic capacitor according to any one of claims 1 to 7, wherein the first electrode layer is a block made of tantalum or niobium.

11. A method for manufacturing a solid electrolytic capacitor, comprising: a dielectric layer forming step of forming a dielectric layer on the outer surface of a first electrode layer; a solid electrolyte layer forming step of forming a solid electrolyte layer on the outer surface of the dielectric layer, the solid electrolyte layer comprising a polymer film containing a crosslinked polymer obtained by crosslinking a polymer having a carbonyl group with a crosslinking agent made of a dihydrazide compound, and a composite of polyethylenedioxythiophene and polystyrenesulfonic acid; and a second electrode layer forming step of forming a conductive polymer film on the outer surface of the solid electrolyte layer by electrolytic polymerization using the solid electrolyte layer as a precoat layer, thereby forming a second electrode layer having the conductive polymer film.

12. A dielectric layer forming step of forming a dielectric layer on the outer surface of a first electrode layer, and forming a composite of polyethylenedioxythiophene and polystyrene sulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton on the outer surface of the dielectric layer. ２ a second electrode layer forming step of forming a second electrode layer having a conductive polymer film on an outer surface of the solid electrolyte layer by electrolytic polymerization using the solid electrolyte layer as a precoat layer.

13. A method for manufacturing a solid electrolytic capacitor, comprising: a dielectric layer forming step of forming a dielectric layer on the outer surface of a first electrode layer; a solid electrolyte layer forming step of forming a solid electrolyte layer on the outer surface of the dielectric layer, the solid electrolyte layer being made of a polymer film containing a crosslinked polymer obtained by crosslinking a composite of polyethylenedioxythiophene and polystyrenesulfonic acid and / or a sulfonic acid compound having a polyethylenedioxythiophene skeleton with a crosslinking agent made of a metal salt containing a metal cation having a valence of two or more; and a second electrode layer forming step of forming a conductive polymer film on the outer surface of the solid electrolyte layer by electrolytic polymerization using the solid electrolyte layer as a precoat layer, thereby forming a second electrode layer having the conductive polymer film.