Dispersion for use in manufacturing electrolytic capacitor, method for manufacturing electrolytic capacitor, and electrolytic capacitor

Abstract

The disclosed dispersion is used in the production of an electrolytic capacitor, and contains a conductive polymer, an insulating material, and a dispersion medium. The insulating material includes at least one type selected from the group consisting of insulating fibers and insulating particles.

Description

Technical Field

[0001] The present invention relates to a dispersion used in the production of an electrolytic capacitor, a method for producing an electrolytic capacitor, and an electrolytic capacitor. Background Art

[0002] As an electrolytic capacitor, there is known an electrolytic capacitor including a winding body of an anode foil, a separator, and a cathode foil. One example of such an electrolytic capacitor includes a conductive polymer layer disposed in the winding body. The conductive polymer layer is formed, for example, by impregnating the winding body with a dispersion containing a conductive polymer. Various proposals have been proposed in the past regarding an electrolytic capacitor including a conductive polymer layer and a method for manufacturing the same.

[0003] Patent document 1 (Japanese Patent No. 5062738) discloses "a conductive composition comprising a conductive polymer synthesized by oxidative polymerization of pyrrole or a derivative thereof using an organic sulfonate and a persulfate, wherein the organic sulfonate is an organic sulfonate comprising a polystyrene sulfonate having a number average molecular weight of 10,000 to 300,000 and an aromatic sulfonate, wherein the aromatic sulfonic acid portion of the aromatic sulfonate accounts for 20 to 50% by mass relative to the polystyrene sulfonic acid portion of the polystyrene sulfonate, and the pH of the dispersion having a total concentration of 1% by mass of the conductive polymer and a substance derived from an added pH-increasing agent is 1.5 to 4.5."

[0004] Patent document 2 (Japanese Patent Publication No. 2007-27767) discloses a method including a step of applying a dispersion a) containing at least particles b of a specified conductive polymer, a binder c) and a dispersant d) to a capacitor body containing at least a solid electrolyte, and a step of at least partially removing the dispersant d) and / or curing the binder c) in order to form an outer layer of the conductive polymer.

[0005] Patent document 3 (Japanese Patent Gazette No. 6951159) discloses "a capacitor comprising an anode including a valve metal, a dielectric layer including an oxide of the valve metal, a cathode made of a conductive material provided on the dielectric layer on the side opposite to the anode, and a solid electrolyte layer formed between the dielectric layer and the cathode, the solid electrolyte layer having a conductive composite including a π-conjugated conductive polymer and a polyanion, and a binder, the binder containing a styrene-butadiene rubber."

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent No. 5062738

[0009] Patent Document 2: Japanese Patent Application Publication No. 2007-27767

[0010] Patent Document 3: Japanese Patent No. 6951159 Summary of the invention

[0011] Problems to be solved by the invention

[0012] When a conductive polymer layer is formed using a conventional dispersion containing a conductive polymer, the performance of the capacitor may be reduced if the conductive polymer adheres to the defective portion of the dielectric layer on the surface of the anode foil, or if the anode portion and the cathode portion are too close. For example, if the conductive polymer adheres to the defective portion of the dielectric layer on the surface of the anode foil, the withstand voltage may be reduced or the leakage current may be increased.

[0013] Under such circumstances, one object of the present invention is to provide an electrolytic capacitor having stable and high performance, and a dispersion liquid and a production method for the electrolytic capacitor.

[0014] Means for solving problems

[0015] A first aspect of the present invention relates to a dispersion used in the production of an electrolytic capacitor, the dispersion comprising a conductive polymer, an insulating substance, and a dispersion medium, wherein the insulating substance comprises at least one selected from insulating fibers and insulating particles.

[0016] Another aspect of the present invention relates to a method for manufacturing an electrolytic capacitor. The method is a method for manufacturing an electrolytic capacitor including an anode portion and a cathode portion having a dielectric layer formed on the surface, the method including a step (X) of arranging a conductive polymer and an insulating material between the dielectric layer and the cathode portion, wherein the insulating material includes at least one selected from insulating fibers and insulating particles.

[0017] Another aspect of the present invention relates to an electrolytic capacitor, which includes an anode portion having a dielectric layer formed on the surface, a cathode portion, and a conductive polymer and an insulating material disposed between the dielectric layer and the cathode portion, wherein the insulating material includes at least one selected from insulating fibers and insulating particles.

[0018] Effects of the Invention

[0019] According to the present invention, an electrolytic capacitor having stable and high performance can be obtained.

[0020] The novel features of the present invention are described in the scope of the appended claims, but the present invention in both structure and content together with other objects and features of the present invention should be more fully understood through the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a side view schematically showing an electrolytic capacitor according to an embodiment of the present invention.

[0022] Figure 2 It is an exploded perspective view schematically showing a capacitor element according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] Hereinafter, the embodiments of the present invention will be described with examples, but the present invention is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes illustrated, but as long as the effect of the present invention can be obtained, other numerical values ​​and other materials can also be applied. In this specification, the description of "numerical value A to numerical value B" includes numerical value A and numerical value B, and can be renamed as "numerical value A or more and numerical value B or less". In the following description, when the lower limit and upper limit of the numerical value of a specific physical property, condition, etc. are illustrated, as long as the lower limit is not above the upper limit, any one of the illustrated lower limits can be arbitrarily combined with any one of the illustrated upper limits. In the following description, when the examples of constituent elements are illustrated, as long as there is no special description, only one of the examples listed can be used, or a plurality of the examples listed can be used in combination.

[0024] (Dispersion used in the manufacture of electrolytic capacitors)

[0025] The dispersion of this embodiment is used for the production of an electrolytic capacitor. Hereinafter, the dispersion of this embodiment may be referred to as "dispersion (D1)".

[0026] The dispersion (D1) contains a conductive polymer, an insulating substance, and a dispersion medium. The insulating substance contains at least one selected from insulating fibers and insulating particles. Hereinafter, the insulating substance may be referred to as "insulating substance (I)".

[0027] The dispersion (D1) contains an insulating substance (I). Therefore, by using the dispersion (D1) to form a conductive polymer layer, it is possible to prevent the conductive polymer from adhering to the defective portion of the dielectric layer on the surface of the anode foil, or the anode portion and the cathode portion from being too close to each other, and as a result, it is possible to prevent the reduction in the withstand voltage of the electrolytic capacitor and the increase in the leakage current. Therefore, by using the dispersion (D1), a stable and high-performance electrolytic capacitor can be obtained. Examples of the constituent elements of the dispersion (D1) are described below.

[0028] (Insulating material (I))

[0029] As described above, the insulating material (I) includes at least one selected from insulating fibers and insulating particles. The insulating material (I) may consist of only insulating fibers, only insulating particles, or both. From the perspective of dispersibility in the dispersion (D1), the insulating material (I) preferably includes insulating fibers.

[0030] The insulating fiber used as the insulating material (I) may include a fiber containing at least one substance selected from cellulose, rayon, aramid, polyester, polyimide and nylon, or may be a fiber made of the at least one substance. By using these insulating fibers, the dispersibility in the dispersion (D1) can be improved, and in particular, the reduction in the withstand voltage of the electrolytic capacitor can be suppressed. Alternatively, insulating fibers other than these may be used.

[0031] The average diameter of the insulating fiber can be greater than 0.1 μm, greater than 1 μm, or greater than 10 μm, and can be less than 100 μm, or less than 50 μm. It should be noted that the cross-section of the insulating fiber can be approximately a perfect circle, or can be a shape other than that (e.g., an ellipse). The so-called diameter of the fiber means the equivalent circle diameter. By setting the average diameter of the insulating fiber to a range of 1 μm to 50 μm (e.g., a range of 10 μm to 50 μm), the effect of the present invention can be improved. The average diameter of the fiber can be obtained by measuring the diameter (equivalent circle diameter) of any position of 30 randomly selected fibers and arithmetically averaging the 30 measured diameters. The equivalent circle diameter can be measured, for example, by analyzing an image of a cross section of the fiber.

[0032] The average fiber length of the insulating fiber may be 100 μm or more. The upper limit of the average fiber length is not particularly limited, and may be, for example, 5000 μm or less. The average fiber length can be obtained by taking the arithmetic mean of the lengths of 30 randomly selected fibers.

[0033] From the viewpoint of suppressing the reduction in the withstand voltage of the electrolytic capacitor, the insulating particles used as the insulating material (I) may include particles containing at least one substance selected from polyolefin, polyester, polytetrafluoroethylene and ceramic (insulating ceramic), or may be particles made of the at least one substance. Alternatively, insulating particles other than these may be used.

[0034] The average particle size of the insulating particles may be 0.1 μm or more, 10 μm or more, or 20 μm or more, and may be 100 μm or less, or 50 μm or less. In this specification, the average particle size is the median diameter (D50) at which the cumulative volume reaches 50% in the volume-based particle size distribution. The median diameter can be obtained using a laser diffraction / scattering particle size distribution measuring device.

[0035] The shape of the insulating particles is not particularly limited, and may be spherical (including ellipsoidal, etc.), scaly, needle-like, or lattice-like. Alternatively, the shape of the insulating particles may not be particularly specified.

[0036] Insulating fibers and insulating particles are sold in various materials and shapes. As the insulating material (I), commercially available insulating fibers and / or insulating particles may be used. Alternatively, insulating fibers and / or insulating particles produced by known methods may be used.

[0037] The content Ci (mass %) of the insulating substance (I) in the dispersion (D1) may be 0.1 mass % or more, or 1.0 mass % or more, and may be 5.0 mass % or less, or 3.0 mass % or less. By setting the content to 1.0 mass % or more, the effect of the present invention can be enhanced. By setting the content to 3.0 mass % or less, the decrease in the conductivity of the conductive polymer layer can be suppressed.

[0038] The ratio Ci / Cc of the content Ci (mass %) to the content Cc (mass %) of the conductive polymer in the dispersion (D1) may be 0.1 or more, or 0.5 or more, or 2.0 or less, or 1.0 or less. By setting the ratio Ci / Cc to 0.5 or more, the effect of the present invention can be enhanced. By setting the ratio Ci / Cc to 1.0 or less, the decrease in the conductivity of the conductive polymer layer can be suppressed.

[0039] (Dispersion medium)

[0040] The dispersion medium is a medium for dispersing the conductive polymer. The dispersion medium preferably contains water. The content of water in the dispersion medium may be 50% by mass or more, 70% by mass or more, 90% by mass or more, or 95% by mass or more. The content may also be 100% by mass. That is, the dispersion medium may be water. The dispersion medium may contain an organic solvent other than water. It should be noted that the additive (A) is not contained in the dispersion medium.

[0041] (Conductive polymer)

[0042] The conductive polymer is not particularly limited as long as it can be used in an electrolytic capacitor. As the conductive polymer, a known conductive polymer used as an electrolyte for an electrolytic capacitor can be used.

[0043] Examples of conductive polymers include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene and their derivatives. The derivatives include polymers with polypyrrole, polythiophene, polyfuran, polyaniline and polyacetylene as basic skeletons. For example, poly(3,4-ethylenedioxythiophene) is included in the derivatives of polythiophene. These conductive polymers can be used alone or in combination. In addition, the conductive polymer can be a copolymer of two or more monomers. The weight average molecular weight of the conductive polymer is not particularly limited, for example, it can be in the range of 1000 to 100000. A preferred example of a conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0044] The conductive polymer may be doped with a dopant. From the viewpoint of suppressing dedoping from the conductive polymer, it is preferred to use a polymer dopant as the dopant. Examples of polymer dopants include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic acid sulfonic acid, polymethacrylic acid sulfonic acid, poly(2-acrylamide-2-methylpropane sulfonic acid), polyisoprene sulfonic acid, polyacrylic acid, etc. They may be used alone or in combination of two or more. At least a portion of them may be added in the form of a salt. A preferred example of a dopant is polystyrene sulfonic acid (PSS). In a preferred example, the conductive polymer is poly(3,4-ethylenedioxythiophene) and the dopant is polystyrene sulfonic acid.

[0045] The dopant may be a dopant containing an acidic group or a polymer dopant containing an acidic group. Examples of acidic groups include sulfonic acid groups, carboxyl groups, etc. The polymer dopant containing an acidic group is a polymer (polymer) in which at least a portion of the structural unit contains an acidic group. Examples of such a polymer dopant include the above-mentioned polymer dopant.

[0046] The weight average molecular weight of the dopant is not particularly limited, but can be in the range of 1,000 to 100,000 from the viewpoint of facilitating the formation of a uniform conductive polymer layer.

[0047] When a conductive polymer doped with a dopant is used, the pH of the dispersion (D1) is preferably less than 7.0, and may be 6.0 or less or 5.0 or less in order to suppress dedoping of the dopant. The pH of the dispersion (D1) may be 1.0 or more, 2.0 or more, or 3.0 or more.

[0048] The conductive polymer may be present in the dispersion (D1) in the form of particles. The average particle size (D50) of the conductive polymer particles may be 10 μm or more, or 20 μm or more, and 100 μm or less.

[0049] The content of the conductive polymer in the dispersion (D1) may be 0.5% by mass or more, or 1.0% by mass or more, or 7.0% by mass or less, 5.0% by mass or less, or 3.0% by mass or less. The content may be in the range of 0.5 to 7.0% by mass, or in the range of 1.0 to 5.0% by mass. In any of these ranges, the upper limit may be 3.0% by mass or 2.0% by mass. In terms of the excellent physical properties of the dispersion (D1) and its stability over time, and the excellent balance between the ESR and cost of the electrolytic capacitor, the content is preferably in the range of 1.0 to 5.0% by mass (e.g., 1.0 to 3.0% by mass).

[0050] The mass of the dopant contained in the dispersion (D1) is not particularly limited, and may be in the range of 0.1 to 5 times (eg, 0.5 to 3 times) the mass of the conductive polymer contained in the dispersion (D1).

[0051] (additive)

[0052] The dispersion (D1) may further contain an additive containing a hydroxyl group, and the dispersion medium may contain water. Hereinafter, the additive may sometimes be referred to as "additive (A)". The ratio Mh / Mt of the total formula weight Mh of the hydroxyl groups contained in the additive (A) to the molecular weight Mt of the additive may be 0.001 or more. In the case of ethylene glycol (HO-CH2-CH2-OH), the molecular weight Mt is 62, and the total formula weight Mh of the two hydroxyl groups is 34. Therefore, Mh / Mt=34 / 62=0.55. In the case where the molecular weight of the additive (A) is not constant, the molecular weight of the additive (A) may use the weight average molecular weight.

[0053] Conductive polymers (e.g., conductive polymer particles) and insulating substances (I) are prone to agglomeration. By adding the additive (A), agglomeration of the two can be suppressed. Therefore, by forming a conductive polymer layer using a dispersion (D1) to which the additive (A) is added, a conductive polymer layer with high dispersibility of the insulating substance (I) can be formed.

[0054] The ratio Mh / Mt may be 0.03 or more, or 0.07 or more, and may be 0.9 or less. By setting the ratio Mh / Mt to 0.03 or more, the effect of the additive (A) can be sufficiently obtained.

[0055] The molecular weight of the additive (A) is preferably 500 or less. By setting the molecular weight to 500 or less, the dispersibility in the dispersion (D1) can be improved. As a result, the additive (A) is easily attached to the defective portion of the dielectric layer. There is no particular limitation on the lower limit of the molecular weight, but it can be 44 or more, 80 or more, or 150 or more. The molecular weight can be 500 or less, 400 or less, 200 or less, or 120 or less.

[0056] The number of hydroxyl groups contained in the additive (A) may be 1 or more or 2 or more, and may be 6 or less or 3 or less. From the viewpoint of the repairability of the defective portion of the dielectric layer, the number of hydroxyl groups is preferably 3 or less.

[0057] Examples of additives (A) include polyols. In this specification, polyols refer to organic compounds containing two or more hydroxyl groups. Examples of polyols include glycols, glycerols, and sugar alcohols. Polyols can be hydrocarbon compounds substituted with two or more hydroxyl groups (e.g., aliphatic hydrocarbons substituted with two or more hydroxyl groups). Additive (A) is preferably a compound soluble in water. Additive (A) can also be an organic compound having three or less hydroxyl groups (e.g., a trivalent or less lower alcohol). The molecular weight of the organic compound can be 500 or less.

[0058] Examples of glycols include alkylene glycols (ethylene glycol, propylene glycol, etc.), diethylene glycol, triethylene glycol, polyalkylene glycols (e.g., polyethylene glycol), polyoxyethylene polyoxypropylene glycol (copolymers of ethylene oxide and propylene oxide), etc. Examples of glycerols include glycerol and polyglycerol, etc. Examples of sugar alcohols include mannitol, xylitol, sorbitol, erythritol, and pentaerythritol, etc.

[0059] The additive (A) may be at least one selected from glycols, glycerols and sugar alcohols. For example, the additive (A) may be at least one selected from ethylene glycol, polyethylene glycol, diethylene glycol, triethylene glycol, glycerol, polyglycerol, erythritol, xylitol, sorbitol and mannitol. A preferred example of the additive (A) is ethylene glycol.

[0060] The ratio Ca / Ci of the content Ca (mass %) of the additive (A) in the dispersion (D1) to the content Ci (mass %) of the insulating substance (I) in the dispersion (D1) may be 0.1 or more, or 1.0 or more, and may be 8.0 or less, or 4.0 or less.

[0061] (Method for producing dispersion (D1))

[0062] The method for producing the dispersion (D1) is not particularly limited. For example, the dispersion (D1) can be produced by dispersing and dissolving the components of the dispersion (D1) in a dispersion medium. Specifically, the dispersion (D1) can be produced by adding the components of the dispersion (D1) to a dispersion medium and stirring.

[0063] (Method for manufacturing electrolytic capacitor)

[0064] The manufacturing method of the present embodiment is a manufacturing method of an electrolytic capacitor including an anode portion and a cathode portion having a dielectric layer formed on the surface. The manufacturing method can be used in the manufacture of any one of a stacked electrolytic capacitor and a sintered electrolytic capacitor. The capacitor element of the stacked electrolytic capacitor includes a stack of at least one sheet-shaped anode portion, at least one sheet-shaped cathode portion, and at least one separator. The stack can also be a stack formed by stacking them in one direction. In this case, the electrolytic capacitor can include a plurality of capacitor elements. Alternatively, the stack can also be a winding body obtained by winding a sheet-shaped anode portion, a sheet-shaped cathode portion, and a separator. The anode portion of the sintered electrolytic capacitor can use a sintered body of a metal containing a valve metal or a metal compound containing a valve metal. Examples of the constituent elements of the electrolytic capacitor will be described later.

[0065] This production method can be implemented using the above-mentioned dispersion (D1). Since the matters described for the dispersion (D1) are applicable to this production method, the overlapping description may be omitted.

[0066] The manufacturing method includes a step (X) of configuring a conductive polymer and an insulating material between a dielectric layer formed on the surface of the anode portion and the cathode portion. The insulating material is the above-mentioned insulating material (I). As described above, the insulating material (I) includes at least one selected from insulating fibers and insulating particles. According to the step (X), it is possible to prevent the conductive polymer from adhering to the defective portion of the dielectric layer on the surface of the anode foil, or the anode portion and the cathode portion from being too close. Therefore, according to the present manufacturing method, a stable and high-performance electrolytic capacitor can be manufactured.

[0067] According to the step (X), a layer containing a conductive polymer can be formed between the dielectric layer and the cathode portion. Hereinafter, the layer containing a conductive polymer may be referred to as a "conductive polymer layer".

[0068] Step (X) can be performed using a first dispersion comprising a conductive polymer, an insulating substance (I) and a dispersion medium. The first dispersion is the above-mentioned dispersion (D1). For example, step (X) may include a step of applying the dispersion (D1) to at least one (coated object) selected from a dielectric layer formed on the surface of the anode portion and a cathode portion and drying it. Alternatively, step (X) may also include a step of applying the dispersion (D1) to at least one (coated object) selected from a dielectric layer formed on the surface of the anode portion, a cathode portion and a separator and drying it.

[0069] The method for configuring the conductive polymer and the insulating substance (I) in step (X) is not particularly limited. For example, the dispersion (D1) can be applied to the object to be coated and dried. The coating method is not particularly limited, and a known method can be used. The coating method can be a method using a coater or a method of spraying the dispersion (D1). Alternatively, the object to be coated can be immersed in the dispersion (D1). The dispersion (D1) can be dried by removing at least a portion of the dispersion medium by heating. For example, the heating can be performed at a temperature of 100°C or above (e.g., 120°C or above, 140°C or above). There is no upper limit to the heating temperature, and it is performed at a temperature that does not affect components such as the conductive polymer, for example, at a temperature below 160°C. There is no limit to the heating time, and the heating time can be determined by taking into account the evaporation amount of the dispersion medium, etc. Drying can be performed under reduced pressure. These coating methods and drying methods can also be applied to the coating and drying described below.

[0070] Step (X) may include step (a), in which a conductive polymer and an insulating substance (I) are attached to the surface of the dielectric layer by applying a dispersion (D1) to the dielectric layer formed on the surface of the anode portion and drying it. According to step (a), it is easy to configure the insulating substance (I) in the defective portion of the dielectric layer. In the case of manufacturing a stacked electrolytic capacitor, step (a) can be performed by applying a dispersion (D1) to the anode portion before forming a stack and drying it. Alternatively, step (a) can be performed by forming a stack and then impregnating the stack with the dispersion (D1) and then drying it. In the case of manufacturing a sintered electrolytic capacitor, it is sufficient to dry the dispersion (D1) after applying (for example, impregnating) the dispersion (D1) to the anode portion (sintered body) where the dielectric layer is formed.

[0071] The electrolytic capacitor may further include a spacer disposed between a dielectric layer formed on the surface of the anode portion and the cathode portion. In this case, step (X) may include steps (X1) and (X2) in sequence. Step (X1) is a step of attaching a conductive polymer and an insulating substance to at least one element by applying a dispersion (D1) to at least one element selected from the dielectric layer, the cathode portion, and the spacer and drying it. Step (X2) is a step of stacking the anode portion, the spacer, and the cathode portion to form a stack. These steps can be preferably used for the manufacture of a stacked electrolytic capacitor. In step (X1), it is preferred to apply a dispersion (D1) to at least the dielectric layer and dry it. Thus, an insulating substance (I) can be configured on the defective portion of the dielectric layer, and the reduction in the performance of the capacitor caused by the defect in the dielectric layer can be suppressed.

[0072] The production method of the present embodiment may further include a step (Z) of impregnating the laminate with a liquid component (hereinafter sometimes referred to as “liquid component (L)”) after the step (X). Examples of the liquid component (L) will be described later.

[0073] The manufacturing method of this embodiment may include a step (Y1) and a step (Y2) after the step (X) and before the step (Z). Hereinafter, the step (Y1) and the step (Y2) are sometimes referred to as "step (Y)". The step (Y1) is a step of impregnating the laminate with a treatment liquid containing an organic compound containing two or more hydroxyl groups and water. Hereinafter, the organic compound and the treatment liquid are sometimes referred to as "organic compound (C)" and "treatment liquid (S)". The step (Y2) is a step of evaporating at least a portion of the water in the treatment liquid (S).

[0074] By performing step (Y), the organic compound (C) can be disposed in the conductive polymer layer. This makes it easier for the liquid component (L) to permeate the laminate in step (Z).

[0075] In step (Y1), the method of impregnating the laminate with the treatment liquid (S) is not limited. For example, the laminate may be immersed in the treatment liquid (S). In step (Y2), the step of evaporating at least a portion of the water in the treatment liquid (S) is not limited. Step (Y2) may be performed under the conditions exemplified for drying the dispersion (D1).

[0076] Examples of the organic compound (C) include polyols. Examples of the polyols include the compounds given as examples of the polyols of the additive (A).

[0077] The water content in the treatment liquid (S) may be 40% by mass or more, 60% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more. The water content may be 99% by mass or less, 95% by mass or less, 90% by mass or less, or 80% by mass or less.

[0078] The content of the organic compound (C) in the treatment liquid (S) may be 1.0 mass % or more, 5.0 mass % or more, 10 mass % or more, or 20 mass % or more. The content may be 60 mass % or less, 40 mass % or less, 20 mass % or less, or 10 mass % or less.

[0079] Step (X) may include step (b1) and step (b2) in sequence. Step (b1) is a step of attaching the insulating substance (I) to the surface of the dielectric layer formed on the surface of the anode portion by applying the second dispersion (D2) containing the insulating substance (I) to the dielectric layer formed on the surface of the anode portion and drying it. Step (b2) is a step of attaching the conductive polymer to the dielectric layer to which the insulating substance (I) is attached by applying the third dispersion (D3) containing the above-mentioned conductive polymer to the dielectric layer to which the insulating substance (I) is attached and drying it. Dispersion (D2) is a dispersion obtained by removing the conductive polymer from the dispersion exemplified as dispersion (D1). Dispersion (D3) is a dispersion containing a conductive polymer. Dispersion (D3) may be the dispersion exemplified as dispersion (D1) or the dispersion obtained by removing the insulating substance (I) from the dispersion exemplified as dispersion (D1).

[0080] The manufacturing method of this embodiment may include a step of forming a conductive polymer layer using a fourth dispersion (D4). Dispersion (D4) is a dispersion obtained by removing an insulating substance (I) from the dispersion exemplified as dispersion (D1). For example, after forming a first conductive polymer layer using dispersion (D1), a second conductive polymer layer may be formed on the first conductive polymer layer using dispersion (D4). It should be noted that in the above-mentioned steps, the step of applying the dispersion (dispersions (D1) to (D4)) and drying the dispersion may be performed only once or may be repeated multiple times.

[0081] The manufacturing process of the electrolytic capacitor is not limited except for the above-mentioned process, and a known manufacturing method can be applied. An example of a manufacturing method of a stacked electrolytic capacitor is described below.

[0082] First, an anode foil (anode part), a cathode foil (cathode part) and a separator are prepared, each of which has a dielectric layer formed on the surface. Then, a laminate is formed using these. The separator is arranged between the anode foil and the cathode foil. Leads are connected to the anode foil and the cathode foil as needed.

[0083] At least one anode foil, at least one cathode foil and at least one separator may be stacked in one direction to form a laminate. Alternatively, the anode foil, the cathode foil and the separator may be wound to form a wound body (laminate). In the wound body, the anode foil, the cathode foil and the separator are stacked in the radial direction. Therefore, the wound body is also a laminate.

[0084] Step (X) may also be performed on a member before forming a laminate. For example, step (X1) and step (X2) may be performed. Alternatively, step (X) may be performed after forming a laminate. In this case, step (X) may be performed by impregnating the laminate with the dispersion (D1) and then drying the laminate. By using step (X), a conductive polymer layer may be formed between the dielectric layer and the cathode foil (cathode portion).

[0085] The laminate (capacitor element) that has undergone step (X) is sealed in an outer package. In this way, a laminated electrolytic capacitor can be manufactured. As described above, step (Z) can be performed after step (X). Alternatively, step (Y) and step (Z) can be performed after step (X).

[0086] The impregnation of the liquid (dispersion (D1), dispersion (D2), dispersion (D3), dispersion (D4), treatment liquid (S), liquid component (L), etc.) into the laminate can be performed by immersing the laminate in the liquid. The subsequent drying can be performed by heating the laminate. The heating can be performed under reduced pressure.

[0087] An example of a method for manufacturing a sintered body type electrolytic capacitor is described below. First, a sintered body (anode portion) having a dielectric layer formed on the surface is prepared. An anode lead is connected to the sintered body as needed.

[0088] Then, the dispersion (D1) is applied to the sintered body having the dielectric layer formed thereon and dried, thereby attaching the conductive polymer and the insulating material to the surface of the dielectric layer (step (a)). By this step, a conductive polymer layer is formed on the surface of the dielectric layer. The method for applying the dispersion (D1) is not limited, and the dispersion (D1) can be applied by a general method or by immersing the sintered body in the dispersion (D1). The subsequent drying can be carried out by the above-mentioned method.

[0089] Then, a cathode portion is formed on the conductive polymer layer. The method for forming the cathode portion is not particularly limited, and it can be formed using a known method. A capacitor element is formed in this way. It should be noted that the anode lead terminal is electrically connected to the anode portion, and the cathode lead terminal is electrically connected to the cathode portion as required. In addition, the capacitor element is sealed with an outer packaging body (e.g., a sealing resin) as required. In this way, a sintered electrolytic capacitor is manufactured.

[0090] An example of the structure and components of the electrolytic capacitor manufactured by the manufacturing method of this embodiment is described below. It should be noted that the structure and components of the electrolytic capacitor are not limited to the following example. Components other than the characteristic components of the present invention can use known components of electrolytic capacitors.

[0091] The electrolytic capacitor includes a capacitor element. The capacitor element includes an anode portion and a cathode portion, and a dielectric layer is formed on the surface of the anode portion. The capacitor element of the stacked electrolytic capacitor further includes a separator disposed between the anode portion and the cathode portion.

[0092] (Anode)

[0093] The anode portion includes an anode body. The anode body may be a porous sintered body or a metal foil with a porous surface. The thickness of the metal foil is not particularly limited and may be in the range of 15 μm to 300 μm. The dielectric layer is formed on at least a portion of the surface of the anode body.

[0094] The material of the anode body can use a valve metal, an alloy containing a valve metal, or a valve metal compound. Examples of valve metals include titanium (Ti), tantalum (Ta), niobium (Nb), aluminum (Al), etc. The anode body can be a sintered body formed by sintering particles that become a material (such as particles of a valve metal). Alternatively, the anode body can also be formed by etching the surface of a metal foil (such as aluminum foil) that becomes a material. The dielectric layer formed on the surface of the anode body can be formed by performing a chemical treatment on the surface of the anode body. The method of the chemical treatment is not limited, and a known chemical treatment method can be applied.

[0095] In the case where the anode body is a sintered body, the anode portion may include an anode wire. The anode wire may be a wire made of metal. Examples of the material of the anode wire include the above-mentioned valve metal, copper, etc. A portion of the anode wire is buried in the anode body, and the remaining portion protrudes from the end surface of the anode body.

[0096] (Cathode)

[0097] The cathode portion may include an electrolyte layer and a cathode foil. Alternatively, the cathode portion may include an electrolyte layer and a cathode lead layer.

[0098] The cathode foil is not particularly limited as long as it has the function of serving as a cathode. Examples of cathode foils include metal foils (e.g., aluminum foil). The type of metal is not particularly limited, and may be a valve metal or an alloy containing a valve metal. The thickness of the cathode foil is not particularly limited, and may be in the range of 15 μm to 300 μm. The surface of the cathode foil may be roughened or subjected to chemical treatment as required.

[0099] The cathode foil may include a conductive coating layer. When the metal foil includes a valve metal, the coating layer may include carbon and at least one metal having a lower ionization tendency than the valve metal. Thus, the acid resistance of the metal foil is easily improved. When the metal foil includes aluminum, the coating layer may include at least one selected from carbon, nickel, titanium, tantalum and zirconium. Among them, the coating layer may include nickel and / or titanium from the aspects of cost and low resistance.

[0100] The cathode lead layer is a conductive layer, and is arranged to cover at least a portion of the electrolyte layer. The cathode lead layer may include a carbon layer formed on the electrolyte layer and a metal paste layer formed on the carbon layer. The carbon layer may be formed of a conductive carbon material such as graphite and a resin. The metal paste layer may be formed of metal particles (such as silver particles) and a resin, and may be formed of a known silver paste, for example.

[0101] (Electrolyte layer)

[0102] The electrolyte layer is disposed between the dielectric layer formed on the surface of the anode portion and the cathode portion. The electrolyte layer includes a conductive polymer (e.g., a conductive polymer layer). The electrolyte layer may also include a conductive polymer and a liquid component (L) (e.g., an electrolyte solution). As described above, the conductive polymer is omitted for repeated description.

[0103] (Liquid component (L))

[0104] Examples of liquid components (L) include non-aqueous solvents and electrolytes. The electrolyte may include a non-aqueous electrolyte containing a non-aqueous solvent and a solute dissolved in the non-aqueous solvent. The liquid component (L) may contain a trace amount of water. It should be noted that in this specification, the liquid component (L) may be a component that is liquid at room temperature (25°C) or a component that is liquid at the temperature when the electrolytic capacitor is used.

[0105] The non-aqueous solvent may be an organic solvent or an ionic liquid. Examples of the non-aqueous solvent include polyols such as ethylene glycol and propylene glycol, cyclic sulfones such as sulfolane (SL), lactones such as γ-butyrolactone (γBL), amides such as N-methylacetamide, N,N-dimethylformamide, and N-methyl-2-pyrrolidone, esters such as methyl acetate, carbonate compounds such as propylene carbonate, ethers such as 1,4-dioxane, ketones such as methyl ethyl ketone, formaldehyde, and the like.

[0106] In addition, a polymer solvent can also be used as a non-aqueous solvent. Examples of polymer solvents include polyalkylene glycol, derivatives of polyalkylene glycol, compounds in which at least one hydroxyl group in a polyol is replaced with polyalkylene glycol (including derivatives), etc. Specifically, examples of polymer solvents include polyethylene glycol (PEG), polyethylene glycol glycerol ether, polyethylene glycol diglycerol ether, polyethylene glycol sorbitol ether, polypropylene glycol, polypropylene glycol glycerol ether, polypropylene glycol diglycerol ether, polypropylene glycol sorbitol ether, polybutylene glycol, etc. Examples of polymer solvents further include copolymers of ethylene glycol-propylene glycol, copolymers of ethylene glycol-butylene glycol, copolymers of propylene glycol-butylene glycol, etc. The non-aqueous solvent can be used alone or in combination of two or more.

[0107] The liquid component (L) may contain an acid component and an alkaline component. Examples of the acid component include maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorcylic acid. Examples of the alkaline component include 1,8-diazabicyclo[5,4,0]undec-7-ene, 1,5-diazabicyclo[4,3,0]non-5-ene, 1,2-dimethylimidazolinium, 1,2,4-trimethylimidazoline, 1-methyl-2-ethyl-imidazoline, 1,4-dimethyl-2-ethylimidazoline, 1-methyl-2-heptylimidazoline, 1-methyl-2-(3'heptyl)imidazoline, 1-methyl-2-dodecylimidazoline, 1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, 1-methylimidazole, and 1-methylbenzimidazole.

[0108] The non-aqueous electrolyte solution includes a non-aqueous solvent and a solute (e.g., an organic salt) dissolved therein. Examples of the non-aqueous solvent constituting the non-aqueous electrolyte solution include the examples of the non-aqueous solvents described above. Examples of the solute include inorganic salts and organic salts. The so-called organic salt is a salt in which at least one of the anions and cations contains an organic substance. Examples of organic salts include trimethylamine maleate, triethylamine borodisalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, mono-1,3-dimethyl-2-ethylimidazolinium phthalate, and the like.

[0109] In order to suppress dedoping of the dopant, the pH of the liquid component (L) may be set to less than 7.0 or less than 5.0, and may be set to 1.0 or more, or 2.0 or more. The pH may be set to 1.0 or more and less than 7.0 (eg, in the range of 2.0 to 5.0).

[0110] (Spacer)

[0111] A porous sheet can be used as the spacer. Examples of porous sheets include woven fabrics, nonwoven fabrics, and microporous films. The thickness of the spacer is not particularly limited and can be in the range of 10 to 300 μm. Examples of materials for the spacer include cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamide, polyimide, polyamide-imide, polyetherimide, rayon, and glass.

[0112] (other)

[0113] The electrolytic capacitor may include other components (leads, outer packaging, etc.) as necessary. The lead and outer packaging are not particularly limited, and known ones can be used.

[0114] (Electrolytic capacitors)

[0115] Hereinafter, the electrolytic capacitor of the present embodiment is sometimes referred to as an "electrolytic capacitor (E)". The electrolytic capacitor (E) can be manufactured using the above-mentioned manufacturing method. Since the matters described in the above-mentioned manufacturing method can also be applied to the electrolytic capacitor (E), repeated descriptions are sometimes omitted. In addition, the matters described in the electrolytic capacitor (E) can also be applied to the above-mentioned manufacturing method. It should be noted that the electrolytic capacitor (E) can also be manufactured using a manufacturing method other than the above-mentioned manufacturing method.

[0116] The electrolytic capacitor (E) includes an anode portion having a dielectric layer formed on the surface, a cathode portion, and a conductive polymer and an insulating material (I) disposed between the dielectric layer and the cathode portion. The insulating material (I) includes at least one selected from insulating fibers and insulating particles.

[0117] The electrolytic capacitor (E) includes a conductive polymer and an insulating material (I) disposed between a dielectric layer and a cathode portion. Therefore, it is possible to prevent the anode portion and the cathode portion from being too close to each other. In addition, by disposing the insulating material (I) near the dielectric layer, it is possible to prevent the conductive polymer from being attached to the defective portion of the dielectric layer on the surface of the anode foil. As a result, it is possible to prevent a decrease in withstand voltage, an increase in leakage current, etc.

[0118] The electrolytic capacitor (E) may further contain an additive (A) disposed between the dielectric layer and the cathode portion. As described above, the additive (A) contains hydroxyl groups, and the ratio Mh / Mt of the total formula weight Mh of the hydroxyl groups contained in the additive to the molecular weight Mt of the additive is 0.03 or more.

[0119] In the electrolytic capacitor (E), at least a portion of the insulating material (I) may adhere to the dielectric layer.

[0120] The electrolytic capacitor (E) may include a laminated body formed of an anode portion, a cathode portion, and a separator disposed between a dielectric layer and the cathode portion. In this case, at least a portion of an insulating material may be attached to at least one element selected from the dielectric layer, the cathode portion, and the separator. The above-mentioned laminated body may be impregnated with a liquid component (L).

[0121] An organic compound (C) containing two or more hydroxyl groups may be disposed between the dielectric layer and the cathode portion.

[0122] The ratio of the content of the conductive polymer between the dielectric layer and the cathode portion to the content of the insulating substance (I) may be within the range exemplified by the ratio Ci / Cc of the content Ci to the content Cc in the dispersion (D1). The ratio of the content of the additive A between the dielectric layer and the cathode portion to the content of the insulating substance (I) may be within the range exemplified by the ratio Ca / Ci of the content Ca to the content Ci in the dispersion (D1).

[0123] Hereinafter, an example of an electrolytic capacitor (E) will be described in detail with reference to the accompanying drawings. The above-mentioned constituent elements can be applied to the constituent elements of the example described below. In addition, the constituent elements of the example described below can be changed based on the above-mentioned description. In addition, the matters described below can also be applied to the above-mentioned embodiment. In addition, in the example described below, constituent elements that are not necessary in the electrolytic capacitor of the present invention can be omitted.

[0124] Figure 1 1 is a cross-sectional view schematically showing an electrolytic capacitor 100 according to an example of the present embodiment. Figure 2 1 is a schematic diagram showing a portion of capacitor element 10 included in electrolytic capacitor 100 . Electrolytic capacitor 100 is a laminated capacitor including a wound body (laminated body).

[0125] The electrolytic capacitor 100 includes a capacitor element 10, a bottomed case 101 accommodating the capacitor element 10, a sealing member 102 sealing an opening of the bottomed case 101, a seat plate 103 covering the sealing member 102, leads 104A and 104B extending from the sealing member 102 and penetrating the seat plate 103, and lead tabs 105A and 105B connecting the leads to electrodes of the capacitor element 10. The vicinity of the opening end of the bottomed case 101 is drawn inward, and the opening end is curled so as to be tightly pressed against the sealing member 102.

[0126] The capacitor element 10 is, for example, Figure 2The winding body is shown. The winding body is formed by winding the anode foil 11, the cathode foil 12 and the separator 13. A dielectric layer (not shown) is formed on the surface of the anode foil 11. The capacitor element 10 includes a conductive polymer layer (not shown) arranged between the anode foil 11 (more specifically, the dielectric layer on the surface of the anode foil 11) and the cathode foil 12. The conductive polymer layer includes an insulating substance (I). The electrolytic capacitor 100 may also include a liquid component (L) (e.g., an electrolyte) impregnated in the capacitor element 10.

[0127] The anode foil 11 and the cathode foil 12 are wound with the separator 13 interposed therebetween. The outermost periphery of the wound body is fixed by the winding stopper 14. Figure 2 The diagram shows a partially unwound state before the outermost circumference of the wound body is fixed.

[0128] The electrolytic capacitor only needs to have at least one capacitor element, and may have a plurality of capacitor elements. The number of capacitor elements included in the electrolytic capacitor may be determined according to the intended use.

[0129] (appendix)

[0130] The following techniques are disclosed using the description of the above embodiments.

[0131] (Technique 1)

[0132] A conductive polymer dispersion is used in the manufacture of electrolytic capacitors.

[0133] It contains conductive polymer, insulating material and dispersion medium.

[0134] The insulating material includes at least one selected from insulating fibers and insulating particles.

[0135] (Technique 2)

[0136] The dispersion according to technology 1 further comprises an additive containing a hydroxyl group,

[0137] The above dispersion medium contains water,

[0138] The ratio Mh / Mt of the total formula weight Mh of the hydroxyl groups contained in the additive to the molecular weight Mt of the additive is 0.03 or more.

[0139] (Technique 3)

[0140] The dispersion according to the technique 1 or 2, wherein the insulating fiber comprises a fiber containing at least one substance selected from the group consisting of cellulose, rayon, aramid, polyester, polyimide and nylon.

[0141] (Technique 4)

[0142] The dispersion according to any one of techniques 1 to 3, wherein the insulating particles include particles containing at least one substance selected from the group consisting of polyolefins, polyesters, polytetrafluoroethylene, and ceramics.

[0143] (Technique 5)

[0144] A method for manufacturing an electrolytic capacitor, comprising an anode portion and a cathode portion having a dielectric layer formed on the surface thereof,

[0145] The manufacturing method includes a step (X) of disposing a conductive polymer and an insulating material between the dielectric layer and the cathode portion.

[0146] The insulating material includes at least one selected from insulating fibers and insulating particles.

[0147] (Technique 6)

[0148] According to the manufacturing method described in technology 5,

[0149] The step (X) includes the step (a) of applying a first dispersion including the conductive polymer, the insulating substance and a dispersion medium to the dielectric layer and drying the dispersion medium, thereby attaching the conductive polymer and the insulating substance to the surface of the dielectric layer.

[0150] (Technique 7)

[0151] According to the manufacturing method described in technology 5,

[0152] The electrolytic capacitor further includes a spacer disposed between the dielectric layer and the cathode portion.

[0153] The above-mentioned step (X) includes in sequence:

[0154] Step (X1) of applying a first dispersion comprising the conductive polymer, the insulating substance and a dispersion medium to at least one element selected from the dielectric layer, the cathode portion and the separator and drying the dispersion, thereby attaching the conductive polymer and the insulating substance to the at least one element; and

[0155] The step (X2) is to stack the anode portion, the separator, and the cathode portion to form a stacked body.

[0156] (Technique 8)

[0157] According to the manufacturing method described in technology 7, wherein,

[0158] After the step (X), the method further includes the step (Z) of impregnating the laminate with a liquid component.

[0159] (Technique 9)

[0160] According to the manufacturing method described in technology 8,

[0161] After the above step (X) and before the above step (Z), comprising:

[0162] Step (Y1), impregnating the laminate with a treatment solution containing an organic compound having two or more hydroxyl groups and water; and

[0163] In step (Y2), at least a portion of the water in the treatment liquid is evaporated.

[0164] (Technology 10)

[0165] According to the manufacturing method described in technology 5,

[0166] The above-mentioned step (X) includes in sequence:

[0167] Step (b1), applying a second dispersion containing the insulating substance on the dielectric layer and drying the dispersion, thereby attaching the insulating substance to the surface of the dielectric layer; and

[0168] Step (b2) of applying a third dispersion containing the conductive polymer on the dielectric layer to which the insulating substance is attached, and drying the dispersion, thereby attaching the conductive polymer to the dielectric layer to which the insulating substance is attached.

[0169] (Technology 11)

[0170] An electrolytic capacitor comprising:

[0171] The anode portion has a dielectric layer formed on the surface,

[0172] The cathode and

[0173] A conductive polymer and an insulating material disposed between the dielectric layer and the cathode portion,

[0174] The insulating material includes at least one selected from insulating fibers and insulating particles.

[0175] (Technology 12)

[0176] According to the electrolytic capacitor described in technology 11, it further contains an additive arranged between the above-mentioned dielectric layer and the above-mentioned cathode part,

[0177] The above additives contain hydroxyl groups.

[0178] The ratio Mh / Mt of the total formula weight Mh of the hydroxyl groups contained in the additive to the molecular weight Mt of the additive is 0.03 or more.

[0179] (Technology 13)

[0180] The electrolytic capacitor according to technology 11 or 12, wherein:

[0181] At least a portion of the insulating substance adheres to the dielectric layer.

[0182] (Technology 14)

[0183] The electrolytic capacitor according to any one of Techniques 11 to 13 comprises a laminated body formed by the anode portion, the cathode portion, and a separator disposed between the dielectric layer and the cathode portion.

[0184] At least a portion of the insulating substance is attached to at least one element selected from the dielectric layer, the cathode portion, and the separator.

[0185] (Technology 15)

[0186] According to the electrolytic capacitor described in technology 14,

[0187] The above-mentioned laminated body is impregnated with a liquid component.

[0188] Example

[0189] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the Examples.

[0190] (Experimental Example 1)

[0191] In Experimental Example 1, a plurality of electrolytic capacitors were produced and evaluated by the following method.

[0192] (Capacitor A1)

[0193] An electrolytic capacitor (capacitor A1) was produced by the following method.

[0194] (a) Preparation of components

[0195] An aluminum foil (thickness 100 μm) was etched to roughen the surface of the aluminum foil. The roughened surface of the aluminum foil was chemically treated to form a dielectric layer. In this way, an anode foil with dielectric layers formed on both sides was obtained. An aluminum foil (thickness 50 μm) was etched to roughen the surface of the aluminum foil to obtain a cathode foil.

[0196] A nonwoven fabric (thickness 50 μm) was prepared as a spacer. The nonwoven fabric was composed of 50% by mass of synthetic fibers (25% by mass of polyester fibers, 25% by mass of aramid fibers) and 50% by mass of cellulose, and contained polyacrylamide as a paper reinforcing agent. The density of the nonwoven fabric was 0.35 g / cm 3 .

[0197] (b) Preparation of dispersion (d1)

[0198] A dispersion (commercially available) was prepared in which particles of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonic acid (PSS) were dispersed in water. Mixed water containing insulating fibers (insulating material (I)) containing cellulose and an additive (A) were added to the dispersion to obtain a dispersion (d1). In the dispersion (d1), the content of the insulating fibers was set to 0.2% by mass, and the content of the additive (A) was set to 5.0% by mass. The content of PEDOT in the dispersion (d1) was set to 2.0% by mass. Ethylene glycol was used as the additive (A).

[0199] (c) Formation of conductive polymer layer

[0200] The dispersion (d1) is applied to one side of the anode foil (the surface of the dielectric layer) using a gravure coater. Thereafter, a drying process is performed to form a conductive polymer layer on one side of the anode foil (the surface of the dielectric layer). The drying process is performed by heating the anode foil coated with the dispersion (d1) at 125°C for 5 minutes. Then, a conductive polymer layer is formed on the other side of the anode foil (the surface of the dielectric layer) using the same method.

[0201] The conductive polymer layer is formed on both sides of the cathode foil by the same method as the method for forming the conductive polymer layer on both sides of the anode foil. Also, the conductive polymer layer is formed on the separator by applying the dispersion (d1) to the separator and then drying the dispersion.

[0202] (d) Fabrication of capacitor elements

[0203] The anode foil, cathode foil and separator are cut into specified sizes. The anode lead connector and cathode lead connector are connected to the anode foil and cathode foil. Then, the anode foil and cathode foil are wound with the separator between them. The anode lead and cathode lead are connected to the ends of each lead connector protruding from the wound body. The obtained wound body is subjected to chemical treatment again to form a dielectric layer on the end face of the anode foil. The end of the outer surface of the wound body is fixed with a stop tape to obtain a capacitor element.

[0204] (e) Infiltration of liquid components

[0205] Phthalic acid and triethylamine (alkali component) were dissolved in ethylene glycol (solvent) at a total concentration of 25 mass % to prepare an electrolyte solution (liquid component (L)). The capacitor element was immersed in the electrolyte solution for 5 minutes in a reduced pressure atmosphere (40 kPa). Thus, the capacitor element (laminated body) was impregnated with the electrolyte solution.

[0206] (f) Sealing of capacitor elements

[0207] The capacitor element impregnated with electrolyte is sealed to produce Figure 1 The electrolytic capacitor shown in the figure was then aged at 95°C for 90 minutes while applying a voltage. Thus, an electrolytic capacitor (capacitor A1) was obtained.

[0208] (Capacitor A2)

[0209] An electrolytic capacitor (capacitor A2) was produced by the following method.

[0210] (a) Preparation of components

[0211] The respective components are prepared in the same manner as in the production of the capacitor A1.

[0212] (b) Preparation of dispersion (cd1)

[0213] A dispersion (cd1) was prepared by the same method and conditions as those for the dispersion (d1), except that no insulating fiber was added.

[0214] (c) Formation of conductive polymer layer

[0215] A conductive polymer layer was formed on the dielectric layer formed on both sides of the anode foil and both sides of the cathode foil using the same method as in the production of capacitor A1 using dispersion (d1). Then, a conductive polymer layer was formed on the separator using the same method as in the production of capacitor A1 except that dispersion (cd1) was used instead of dispersion (d1).

[0216] (d) Fabrication of capacitor A2

[0217] Thereafter, the capacitor element was manufactured, impregnated with the liquid component, and sealed by the same method as that for manufacturing the capacitor A1. In this way, the capacitor A2 was manufactured.

[0218] (Fabrication of capacitor C1)

[0219] Capacitor C1 was produced by the same method as capacitor A1 except that the dispersion used for forming the conductive polymer layer on each component member was changed as shown in Table 1.

[0220] (evaluate)

[0221] The withstand voltage and the equivalent series resistance (ESR) at 100 kHz of the produced capacitors were measured. Note that the evaluation was performed by preparing three capacitors, respectively, for capacitors A1, A2, and C1, and calculating the arithmetic average of the measured values.

[0222] Some of the formation conditions of the conductive polymer layer and the evaluation results are shown in Table 1. Note that capacitors A1 and A2 are capacitors (E) according to the present embodiment, and capacitor C1 is a capacitor according to a comparative example.

[0223]

[0224] As shown in Table 1, the withstand voltage is improved by using the dispersion (d1) to which the insulating fiber is added. In addition, the ESR of capacitors A1 and A2 is almost the same as the ESR of comparative example C1. As described above, according to this embodiment, an electrolytic capacitor with stable and high performance can be obtained.

[0225] Industrial Applicability

[0226] The present invention can be applied to an electrolytic capacitor, a method for manufacturing the same, and a dispersion used in manufacturing the electrolytic capacitor.

[0227] Although the present invention has been described with respect to the present preferred embodiments, such disclosure should not be construed in a limiting sense. Upon reading the above disclosure, various modifications and changes will undoubtedly be apparent to those skilled in the art in the technical field of the present invention. Therefore, the scope of the appended claims should be interpreted as including all modifications and changes without departing from the true spirit and scope of the present invention.

[0228] Description of Reference Numerals

[0229] 10 capacitor element, 11 anode foil, 12 cathode foil, 13 spacer, 14 anti-roll tape, 100 electrolytic capacitor, 101 bottom case, 102 sealing member, 103 seat plate.

Claims

1. A conductive polymer dispersion used in the manufacture of an electrolytic capacitor. Contains conductive polymers, insulating materials and dispersion media. The insulating material includes at least one selected from insulating fibers and insulating particles.

2. The dispersion according to claim 1, further comprising an additive containing a hydroxyl group, The dispersion medium comprises water, The ratio Mh / Mt of the total formula weight Mh of the hydroxyl groups contained in the additive to the molecular weight Mt of the additive is 0.03 or more.

3. The dispersion according to claim 1 or 2, wherein The insulating fiber includes a fiber containing at least one substance selected from the group consisting of cellulose, rayon, aramid, polyester, polyimide, and nylon.

4. The dispersion according to claim 1 or 2, wherein The insulating particles include particles containing at least one substance selected from the group consisting of polyolefin, polyester, polytetrafluoroethylene, and ceramics.

5. A method for manufacturing an electrolytic capacitor, the electrolytic capacitor comprising an anode portion and a cathode portion having a dielectric layer formed on the surface thereof, The manufacturing method includes a step (X) of disposing a conductive polymer and an insulating material between the dielectric layer and the cathode portion. The insulating material includes at least one selected from insulating fibers and insulating particles.

6. The manufacturing method according to claim 5, wherein: The step (X) includes a step (a) of applying a first dispersion including the conductive polymer, the insulating substance, and a dispersion medium to the dielectric layer and drying the dispersion medium to adhere the conductive polymer and the insulating substance to the surface of the dielectric layer.

7. The manufacturing method according to claim 5, wherein: The electrolytic capacitor further includes a spacer disposed between the dielectric layer and the cathode portion, The step (X) comprises in sequence: Step (X1) of applying a first dispersion comprising the conductive polymer, the insulating substance and a dispersion medium to at least one element selected from the dielectric layer, the cathode portion and the spacer and drying the dispersion, thereby attaching the conductive polymer and the insulating substance to the at least one element; and The step (X2) is to stack the anode portion, the separator, and the cathode portion to form a stacked body.

8. The manufacturing method according to claim 7, wherein: After the step (X), the method further includes the step (Z) of impregnating the laminate with a liquid component.

9. The manufacturing method according to claim 8, wherein: After the step (X) and before the step (Z), the method comprises: step (Y1), impregnating the laminate with a treatment solution containing an organic compound having two or more hydroxyl groups and water; and In step (Y2), at least a portion of the water in the treatment liquid is evaporated.

10. The manufacturing method according to claim 5, wherein: The step (X) comprises in sequence: Step (b1), applying a second dispersion containing the insulating substance on the dielectric layer and drying the dispersion, thereby attaching the insulating substance to the surface of the dielectric layer; and Step (b2) of applying a third dispersion containing the conductive polymer on the dielectric layer to which the insulating substance is attached, and drying the dispersion, thereby attaching the conductive polymer to the dielectric layer to which the insulating substance is attached.

11. An electrolytic capacitor comprising: The anode portion has a dielectric layer formed on the surface, The cathode and a conductive polymer and an insulating material disposed between the dielectric layer and the cathode portion, The insulating material includes at least one selected from insulating fibers and insulating particles.

12. The electrolytic capacitor according to claim 11, further comprising an additive disposed between the dielectric layer and the cathode portion, The additive contains hydroxyl groups, The ratio Mh / Mt of the total formula weight Mh of the hydroxyl groups contained in the additive to the molecular weight Mt of the additive is 0.03 or more.

13. The electrolytic capacitor according to claim 11 or 12, wherein: At least a portion of the insulating substance adheres to the dielectric layer.

14. The electrolytic capacitor according to claim 11 or 12, comprising a laminated body formed by the anode portion, the cathode portion, and a spacer disposed between the dielectric layer and the cathode portion, At least a portion of the insulating material is attached to at least one element selected from the dielectric layer, the cathode portion, and the spacer.

15. The electrolytic capacitor according to claim 14, wherein: The laminated body is impregnated with a liquid component.

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