Method for manufacturing electrolytic capacitor, electrolytic capacitor, first processing liquid, and second processing liquid

Abstract

A method for manufacturing an electrolytic capacitor includes: a step for preparing a first processing liquid containing a first conductive polymer component; a step for preparing a second processing liquid containing a second conductive polymer component; a step for applying a first treatment liquid to the spacer to adhere a first conductive polymer component; a step for applying a second processing liquid to at least one of the anode foil and the cathode foil provided with the dielectric layer and adhering a second conductive polymer component; a step in which the anode foil, the separator, and the cathode foil are laminated in this order to produce a capacitor element; and a step for impregnating the capacitor element with a liquid component. The first treatment liquid contains less than 10% by mass of the first polyol or does not substantially contain the first polyol. The second processing liquid contains 10% by mass or more of a second polyol.

Description

Technical Field

[0001] The present application relates to a method for manufacturing an electrolytic capacitor, an electrolytic capacitor, a first treatment liquid, and a second treatment liquid. Background Art

[0002] Capacitors used in electronic devices are required to have a large capacitance and a small equivalent series resistance (ESR) in the high-frequency region. As a capacitor with a large capacitance and a low ESR, an electrolytic capacitor using a conductive polymer such as polypyrrole, polythiophene, polyfuran, or polyaniline as a solid electrolyte is expected.

[0003] In Patent Document 1, there is disclosed "a method for manufacturing an electrolytic capacitor, the manufacturing method including: a step of preparing an electrode foil; a step of preparing a first conductive polymer dispersion liquid containing a first conductive polymer component and a first dispersion medium; a step of forming a first conductive polymer layer containing the first conductive polymer component by applying the first conductive polymer dispersion liquid on the surface of the electrode foil by a coating method and then removing at least a part of the first dispersion medium; and a step of manufacturing a capacitor element using the electrode foil on which the first conductive polymer layer is formed."

[0004] In Patent Document 2, there is disclosed "a method for manufacturing an electrolytic capacitor, the manufacturing method including: a step of preparing an anode foil, a cathode foil, and a fiber structure having a dielectric layer; a step of preparing a conductive polymer dispersion liquid containing a conductive polymer component and a dispersion medium; a step of manufacturing a spacer by applying the conductive polymer dispersion liquid on the fiber structure and then removing at least a part of the dispersion medium; and a step of manufacturing a capacitor element by laminating the anode foil, the spacer, and the cathode foil in this order, the dispersion medium containing water, the fiber structure containing 50% by mass or more of synthetic fibers, and the density of the fiber structure being 0.2 g / cm 3 or more and less than 0.45 g / cm 3 ."

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: International Publication No. 2020 / 158780

[0008] Patent Document 2: International Publication No. 2020 / 158783 Summary of the Invention

[0009] One aspect of the present application relates to a method for manufacturing an electrolytic capacitor. The manufacturing method includes: a step of preparing an anode foil, a cathode foil, and a spacer each having a dielectric layer; a step of preparing a first treatment liquid containing a first conductive polymer component; a step of preparing a second treatment liquid containing a second conductive polymer component; a step of applying the first treatment liquid to the spacer to attach the first conductive polymer component; a step of applying the second treatment liquid to at least one of the anode foil and the cathode foil to attach the second conductive polymer component; a step of laminating the anode foil, the spacer to which the first conductive polymer component is attached, and the cathode foil in sequence to produce a capacitor element after the step of attaching the second conductive polymer component; and a step of impregnating a liquid component into the capacitor element. The first treatment liquid contains a first polyol or substantially does not contain a first polyol, and the content of the first polyol in the first treatment liquid is 0% by mass or more and less than 10% by mass. The second treatment liquid contains a second polyol, and the content of the second polyol in the second treatment liquid is 10% by mass or more.

[0010] Another aspect of the present application relates to an electrolytic capacitor. The electrolytic capacitor includes a capacitor element and a liquid component. The capacitor element includes: an anode foil having a dielectric layer, a cathode foil, a spacer interposed between the anode foil and the cathode foil, a first conductive polymer component attached to the spacer, and a second conductive polymer component attached to at least one of the anode foil and the cathode foil. The first conductive polymer component has a higher solubility in water than the second conductive polymer component.

[0011] Another aspect of the present application relates to a first treatment liquid that is applied to a spacer constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component. The first treatment liquid contains a first conductive polymer component and contains a first polyol or substantially does not contain a first polyol, and the content of the first polyol in the first treatment liquid is 0% by mass or more and less than 10% by mass. The first conductive polymer component attached to the spacer by applying the first treatment liquid to the spacer migrates to an adjacent other conductive polymer component when the liquid component is impregnated into the capacitor element.

[0012] Another aspect of the present application relates to a second treatment liquid that is used together with the first treatment liquid and is applied to at least one of an anode foil and a cathode foil constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component. The second treatment liquid contains a second conductive polymer component and a second polyol, and the content of the second polyol in the second treatment liquid is 10% by mass or more.

[0013] Advantages of the Invention

[0014] According to the present application, the ESR of the electrolytic capacitor can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. is a cross-sectional view schematically showing an electrolytic capacitor according to an embodiment of the present application.

[0016] Figure 2 FIG. is a perspective view showing a part of the wound body unfolded. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] Before describing the embodiments of the present application, the problems of the prior art will be briefly described. A dispersion liquid of a conductive polymer component is coated on the surfaces of an anode foil, a cathode foil, and a spacer, respectively, so that the conductive polymer component adheres thereto. Then, a capacitor element is manufactured by disposing the spacer between the anode foil and the cathode foil. However, the interfacial resistance between the anode foil, the cathode foil, and the spacer is large, and the ESR may increase.

[0018] Hereinafter, embodiments of the present application will be described as examples. However, the present application is not limited to the examples described below. In the following description, specific numerical values and materials may be illustrated. However, as long as the effects of the present application can be obtained, other numerical values and materials may also be applied. In this specification, a description such as "numerical value A to numerical value B" includes numerical value A and numerical value B, and may be read as "numerical value A or more and numerical value B or less". In the following description, when lower and upper limits of specific physical properties, conditions, etc. are illustrated, as long as the lower limit is not more than the upper limit, any one of the illustrated lower limits and any one of the illustrated upper limits may be arbitrarily combined. When multiple materials are illustrated, one of them may be selected and used alone, or two or more of them may be used in combination.

[0019] In addition, the present application includes a combination of matters described in two or more claims arbitrarily selected from the multiple claims described in the scope of the appended claims. That is, as long as there is no technical contradiction, matters described in two or more claims arbitrarily selected from the multiple claims described in the scope of the appended claims can be combined.

[0020] [Method for Manufacturing an Electrolytic Capacitor]

[0021] The method for manufacturing an electrolytic capacitor according to an embodiment of the present application includes a first step to a seventh step.

[0022] First step: Prepare an anode foil, a cathode foil, and a spacer each having a dielectric layer.

[0023] Second process: Prepare a first treatment liquid containing a first conductive polymer component. The first treatment liquid contains a first polyol or substantially does not contain a first polyol, and the content of the first polyol in the first treatment liquid is 0 mass% or more and less than 10 mass%.

[0024] Third process: Prepare a second treatment liquid containing a second conductive polymer component. The second treatment liquid contains a second polyol, and the content of the second polyol in the second treatment liquid is 10 mass% or more.

[0025] Fourth process: Coat the first treatment liquid on the spacer to attach the first conductive polymer component. By the fourth process, a first conductive polymer layer containing the first conductive polymer component is formed on at least the surface of the spacer.

[0026] Fifth process: Coat the second treatment liquid on at least one of the anode foil and the cathode foil to attach the second conductive polymer component. By the fifth process, a second conductive polymer layer containing the second conductive polymer component is formed on at least one of the surfaces of the anode foil and the cathode foil.

[0027] Sixth process: Stack the anode foil, the spacer with the first conductive polymer component attached, and the cathode foil in sequence to fabricate a capacitor element.

[0028] Seventh process: Impregnate the capacitor element with a liquid component.

[0029] Hereinafter, the second treatment liquid coated on the anode foil is also referred to as the "2A treatment liquid". The second treatment liquid coated on the cathode foil is also referred to as the "2B treatment liquid". The 2A treatment liquid contains a 2A conductive polymer component as the second conductive polymer component and a 2A polyol as the second polyol. The 2B treatment liquid contains a 2B conductive polymer component as the second conductive polymer component and a 2B polyol as the second polyol. The 2A treatment liquid and the 2B treatment liquid may have the same liquid composition as each other or may have different liquid compositions from each other. It should be noted that the second treatment liquid may be coated only on the anode foil, may be coated only on the cathode foil, or may be coated on both the anode foil and the cathode foil. The anode foil, the cathode foil, and the spacer are collectively referred to as "constituent components". The anode foil and the cathode foil are collectively referred to as "electrode foils".

[0030] Polyols contribute to the improvement of the crystallinity (orientation) of the conductive polymer component and the resulting improvement in conductivity. In addition, it contributes to the improvement of the adhesion (impregnation) of the conductive polymer component to the constituent components.

[0031] By including a large amount (10% by mass or more) of a second polyol in the second treatment liquid, the crystallinity of the second conductive polymer component is improved, and the conductivity of the second conductive polymer component is increased. In addition, the second conductive polymer component has high adhesion to the surface of the electrode foil, and maintains the state where the second conductive polymer component firmly adheres to the surface of the electrode foil even after the infiltration of the liquid component. The electrode foil with the second conductive polymer component attached using the second treatment liquid is particularly advantageous in terms of low ESR and high capacitance in the low-frequency region.

[0032] The first treatment liquid contains a small amount (less than 10% by mass) of the first polyol, or substantially does not contain the first polyol. Therefore, the adhesion of the first conductive polymer component to the surface of the spacer is low. As a result, in the seventh step (the step of infiltrating the liquid component into the capacitor element), the liquid component infiltrates between the electrode foil and the spacer, and the first conductive polymer component (especially the first conductive polymer component attached to the outer surface of the spacer) migrates to the second conductive polymer component. Thereby, a plurality of conductive paths are formed between the first conductive polymer component attached to the surface of the spacer and the second conductive polymer component attached to the surface of the electrode foil, and the interfacial resistance between the electrode foil and the spacer is reduced.

[0033] Based on the above description, by using the first treatment liquid for coating the spacer and the second treatment liquid for coating the electrode foil, an electrolytic capacitor with low ESR can be obtained.

[0034] (First step)

[0035] Prepare an anode foil, a cathode foil, and a spacer having a dielectric layer. Hereinafter, these constituent components will be described.

[0036] (Anode foil having a dielectric layer)

[0037] Examples of the anode foil include a metal foil containing at least one of valve metal such as titanium, tantalum, aluminum, and niobium, and may also be a metal foil of valve metal (such as aluminum foil). The anode foil may contain the valve metal in the form of an alloy containing the valve metal or a compound containing the valve metal. The thickness of the anode foil may be 15 μm or more and 300 μm or less. The surface of the anode foil can be roughened by etching or the like. The anode foil with the roughened surface has a core portion and a porous portion continuous with the core portion.

[0038] A dielectric layer is formed on the surface of the anode foil. The dielectric layer is formed, for example, by subjecting the anode foil to a forming process. In this case, the dielectric layer may contain an oxide of a valve metal (such as aluminum oxide). When the anode foil having a porous portion on its surface is subjected to a forming process, the dielectric layer is formed so as to cover the metal skeleton constituting the porous portion. It should be noted that the dielectric layer only needs to function as a dielectric and may be formed of a dielectric other than the oxide of the valve metal.

[0039] In an electrolytic capacitor, a conductive polymer layer may not be formed on the end face of the anode foil. On the other hand, it is desirable to form a dielectric layer on the end face of the anode foil.

[0040] (Cathode foil)

[0041] The cathode foil only needs to have the function of a cathode and is not particularly limited. Examples of the cathode foil include metal foils (such as aluminum foils). 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 may be 15 μm or more and 300 μm or less. The surface of the cathode foil may be roughened or subjected to a forming process as needed.

[0042] The cathode foil may include a conductive coating layer. When the metal foil contains a valve metal, the coating layer may contain carbon and at least one metal having a lower ionization tendency than the valve metal. Thereby, the acid resistance of the metal foil is easily improved. When the metal foil contains aluminum, the coating layer may contain at least one selected from carbon, nickel, titanium, tantalum, and zirconium. Among them, from the viewpoints of cost and low resistance, the coating layer may contain nickel and / or titanium.

[0043] The thickness of the coating layer may be 5 nm or more or 10 nm or more, and may be 200 nm or less. The coating layer may be formed by vapor-depositing or sputtering the above metals on the metal foil. Alternatively, the coating layer may also be formed by vapor-depositing a conductive carbon material on the metal foil or coating a carbon paste containing a conductive carbon material. Examples of the conductive carbon material include graphite, hard carbon, soft carbon, carbon black, etc.

[0044] (Spacer)

[0045] A porous sheet may be used as the spacer. Examples of the porous sheet include woven fabric, non-woven fabric, and microporous membrane. The thickness of the spacer is not particularly limited and may be in the range of 10 to 300 μm. Examples of the material of the spacer include cellulose, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, vinylon, nylon, aromatic polyamide, polyimide, polyamideimide, polyetherimide, rayon, glass, etc.

[0046] (Second process)

[0047] (First treatment liquid)

[0048] In the second step, a first treatment liquid containing a first conductive polymer component is prepared. The first treatment liquid is applied to a spacer constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component.

[0049] The first treatment liquid contains a first polyol or substantially does not contain a first polyol. Note that the so-called "substantially does not contain" means less than the detection limit of an analytical device (such as a liquid chromatography analysis device). From the viewpoint of reducing ESR, the content of the first polyol in the first treatment liquid is 0% by mass or more and less than 10% by mass, preferably 0% by mass or more and 5% by mass or less.

[0050] A first conductive polymer component is dispersed (or dissolved) in the first treatment liquid. The first treatment liquid may contain water as a dispersion medium (or solvent), or may contain water and a first polyol. The first polyol may be a compound used as an organic solvent, or may be a mixed dispersion medium (mixed solvent) of water and the first polyol. Water in which the first polyol is dissolved may also be used as a dispersion medium (or solvent). As the dispersion medium (or solvent), other components may also be included in addition to water and the first polyol. As other components, non-aqueous solvents exemplified in the liquid component may be included.

[0051] In the first treatment liquid, the mass of the first polyol is preferably less than 5 times the mass of the first conductive polymer component, and more preferably 2.5 times or less the mass of the first conductive polymer component.

[0052] (Third step)

[0053] (Second treatment liquid)

[0054] In the third step, a second treatment liquid containing a second conductive polymer component is prepared. The second treatment liquid is used together with the first treatment liquid and applied to an electrode foil constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component. That is, the second A treatment liquid is applied to the anode foil, and the second B treatment liquid is applied to the cathode foil.

[0055] The second treatment liquid contains a second conductive polymer and a second polyol. From the viewpoint of reducing ESR, the content of the second polyol in the second treatment liquid is 10% by mass or more, preferably 10% by mass or more (or 15% by mass or more) and 30% by mass or less.

[0056] The second conductive polymer component is dispersed (or dissolved) in the second treatment liquid. In the second treatment liquid, water and a second polyol may be included as a dispersion medium (or solvent). The second polyol may be a compound used as an organic solvent, or a mixed dispersion medium (mixed solvent) of water and the second polyol. Water in which the second polyol is dissolved may also be used as a dispersion medium (or solvent). As the dispersion medium (or solvent), other components other than water and the second polyol may also be included. As the other components, non-aqueous solvents exemplified in the liquid components may be included.

[0057] In the second treatment liquid, the mass of the second polyol is preferably 5 times or more and 30 times or less, more preferably 5 times or more and 25 times or less, and still more preferably 7 times or more and 15 times or less the mass of the second conductive polymer component.

[0058] Hereinafter, the polyol and the conductive polymer component used in the treatment liquid (the first treatment liquid and the second treatment liquid) will be described.

[0059] (Polyol)

[0060] The polyol preferably contains at least one selected from diol compounds, glycerol compounds, and sugar alcohol compounds. In this case, the conductive polymer component is liable to swell. The second polyol may be the same compound as the first polyol or a different compound from the first polyol.

[0061] Examples of the diol compound include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycol (for example, polyethylene glycol), polyoxyethylene polyoxypropylene glycol (ethylene oxide - propylene oxide copolymer), and the like. Examples of the glycerol compound include glycerol and polyglycerol. Examples of the sugar alcohol compound include mannitol, xylitol, sorbitol, erythritol, and pentaerythritol. From the viewpoints of affinity with the treatment liquid and film-forming property of the conductive polymer component, ethylene glycol is preferred among them.

[0062] The boiling point of the polyol may be higher than 100 °C, or may be 110 °C or higher, 150 °C or higher, or 200 °C or higher, or may be 400 °C or lower, 300 °C or lower, 250 °C or lower, or 200 °C or lower. This boiling point may be in the range of 110 °C to 400 °C (for example, in the range of 150 °C to 350 °C).

[0063] (Conductive polymer component)

[0064] The conductive polymer component contains a conductive polymer and may also consist only of a conductive polymer. Alternatively, the conductive polymer component may also contain a conductive polymer and a dopant. The second conductive polymer component may use the same compound as the first conductive polymer component or may use a compound different from the first conductive polymer component.

[0065] Examples of the conductive polymer include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, and their derivatives. The derivative includes a polymer having polypyrrole, polythiophene, polyfuran, polyaniline, or polyacetylene as a basic skeleton. For example, derivatives of polythiophene include poly(3,4-ethylenedioxythiophene). These conductive polymers can be used alone or in combination of multiple kinds. In addition, the conductive polymer may also be a copolymer of two or more monomers. The weight-average molecular weight of the conductive polymer is not particularly limited and can be, for example, in the range of 1,000 to 100,000. A preferred example of the conductive polymer is poly(3,4-ethylenedioxythiophene) (PEDOT).

[0066] A dopant can be doped in the conductive polymer. From the viewpoint of suppressing the dedoping from the conductive polymer, a polymer dopant is preferably used as the dopant. Examples of the polymer dopant include polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polyacrylic acid sulfonic acid, polymethacrylic acid sulfonic acid, poly(2-acrylamide-2-methylpropanesulfonic acid), polyisoprenesulfonic acid, polyacrylic acid, etc. They can be used alone or in combination of two or more kinds. At least a part of them can be added in the form of a salt. A preferred example of the dopant is polystyrenesulfonic acid (PSS).

[0067] The dopant can be a dopant containing an acidic group or a polymer dopant containing an acidic group. Examples of the acidic group include a sulfonic acid group, a carboxyl group, etc. The polymer dopant containing an acidic group is a polymer (polymer) in which at least a part of the structural units contains an acidic group. Examples of such a polymer dopant include the above-mentioned polymer dopants.

[0068] The weight-average molecular weight of the dopant is not particularly limited. From the viewpoint of easily forming a uniform conductive polymer layer, the weight-average molecular weight of the dopant can be set in the range of 1,000 to 100,000.

[0069] The dopant can be polystyrenesulfonic acid and the conductive polymer can be poly(3,4-ethylenedioxythiophene). That is, the conductive polymer component can be poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonic acid.

[0070] When using a conductive polymer doped with a dopant, in order to suppress the dedoping of the dopant, the pH of the treatment liquid is preferably less than 7.0, and may also be 6.0 or less, or 5.0 or less. The pH of the treatment liquid may also be 1.0 or more, or 2.0 or more.

[0071] The conductive polymer component may exist in the treatment liquid in the form of particles. In the volume-based particle size distribution of the particles of the conductive polymer component, the most frequent value of the particle diameter may be 10 nm or more, or 20 nm or more, and may be 1000 nm or less, 500 nm or less, 200 nm or less, or 100 nm or less. The volume-based particle size distribution can be determined using a laser diffraction / scattering particle size distribution measuring device.

[0072] The above-mentioned most frequent value of the particle diameter of the particles of the conductive polymer component may be in the range of 20 nm to 200 nm (for example, in the range of 20 nm to 100 nm). In addition, in the volume-based particle size distribution, the volume-based ratio of the particles with a particle diameter in the range of 20 nm to 100 nm may be 90% or more of the whole. According to these ranges, it is easy to form a conductive polymer layer containing a conductive polymer component in the pores of the components (electrode foil and spacer).

[0073] The content rate of the conductive polymer component in the treatment liquid may be 0.5% by mass or more, or 1.0% by mass or more, and may be 4.0% by mass or less, 3.0% by mass or less, or 2.0% by mass or less. The content rate may be in the range of 0.5 to 4.0% by mass, or in the range of 1.0 to 4.0% by mass. In any of these ranges, the upper limit can be set to 3.0% by mass or 2.0% by mass. From the aspects of excellent physical properties of the treatment liquid and its stability over time, and good balance between the ESR and cost of the electrolytic capacitor, the content rate is preferably in the range of 1.0% to 3.0%. It should be noted that when the treatment liquid contains a dopant, the mass of the dopant is included in the mass of the conductive polymer component.

[0074] (Fourth process and fifth process)

[0075] The treatment liquid is coated on each component to attach the conductive polymer component. Thereby, a conductive polymer layer containing a conductive polymer component is formed on the surface of the component. After coating, a drying treatment can be performed on the coating film to remove at least a part of the dispersion medium (solvent). The drying treatment can be carried out by heat treatment or under reduced pressure.

[0076] In the fourth process, a first treatment liquid is applied to the spacer to attach a first conductive polymer component. Thereby, a first conductive polymer layer containing the first conductive polymer component is formed on the surface of the spacer. In the fifth process, a second treatment liquid is applied to the electrode foil to attach a second conductive polymer component. That is, a second A treatment liquid is applied to the anode foil (dielectric layer) to attach a second A conductive polymer component. Thereby, a second A conductive polymer layer containing the second A conductive polymer component is formed on the surface of the anode foil (on the dielectric layer). A second B treatment liquid is applied to the cathode foil to attach a second B conductive polymer component. Thereby, a second B conductive polymer layer containing the second B conductive polymer component is formed on the surface of the cathode foil.

[0077] The method of applying the treatment liquid is not limited, and a known method can be used for application. For example, it can be a method using a coater, or the treatment liquid can be sprayed, or the object to be coated can be immersed in the treatment liquid. Examples of the method using a coater include the gravure coating method, the die coating method, etc. It should be noted that, in the method of applying the first treatment liquid to the spacer, a method of infiltrating the first treatment liquid into the spacer is included. The first treatment liquid applied to the spacer infiltrates into the interior of the spacer, and a first conductive polymer layer can be formed in the entire thickness direction of the spacer.

[0078] The fourth process and / or the fifth process may include, after the application of the treatment liquid, a process (a) of removing a part of the dispersion medium (or solvent) in such a manner that a polyol remains in the conductive polymer layer. In this case, it is possible to suppress excessive shrinkage of the formed conductive polymer layer and improve the infiltration property of the liquid component.

[0079] As long as a part of the dispersion medium (or solvent) can be removed in such a manner that a polyol remains in the conductive polymer layer, the method of removing the dispersion medium (or solvent) from the treatment liquid is not particularly limited. The removal of the dispersion medium (or solvent) can be carried out by heating and / or reducing the pressure, and heating is preferably carried out at least.

[0080] In the case of heating, it is preferable to remove a part of the dispersion medium (or solvent) by heating at a temperature of 100 °C or higher. By heating at a temperature of 100 °C or higher, water in the treatment liquid can be quickly removed. The heating temperature is preferably a temperature at which the polyol does not boil or decompose. In the case where the polyol is a compound without a definite boiling point, it is preferable to heat at a temperature at which the evaporation of the polyol is small and the polyol does not decompose. The heating temperature can be 100 °C or higher, 120 °C or higher, or 140 °C or higher, and can be 200 °C or lower, or 160 °C or lower. The heating temperature can be in the range of 100 °C to 200 °C. The heating time is not particularly limited as long as it is a time that can appropriately remove a part of the dispersion medium (or solvent). The heating time in one example is in the range of 5 to 60 minutes.

[0081] In the case of forming the second conductive polymer layer on both surfaces of the anode foil, it is possible to coat the treatment liquid on one surface and then heat it, and coat the treatment liquid on the other surface and then heat it. In the case of forming the second conductive polymer layer on both surfaces of the cathode foil, the same method can also be applied.

[0082] For example, the step (a) can be carried out in such a way that the mass of the polyol in the conductive polymer layer is greater than the mass of water in the conductive polymer layer. In this case, in the treatment liquid with a high water content, the conductive polymer component is liable to swell, and the conductive polymer layer can be formed while maintaining a swollen state to a certain extent. In the seventh step, the liquid component is liable to infiltrate into the second conductive polymer layer.

[0083] (Step 6)

[0084] The anode foil with the second conductive polymer component attached, the spacer with the first conductive polymer component attached, and the cathode foil with the second conductive polymer component attached are laminated in sequence to produce a capacitor element. The capacitor element has a solid electrolyte containing the first conductive polymer component and the second conductive polymer component. Hereinafter, the spacer with the first conductive polymer component attached is also referred to as "spacer S". The anode foil with the second conductive polymer component attached is also referred to as "anode foil P". The cathode foil with the second conductive polymer component attached is also referred to as "cathode foil N".

[0085] In the sixth step, the anode foil P and the cathode foil N can be wound with a spacer S interposed therebetween to obtain a wound body. In the sixth step, the anode foil P and the cathode foil N can also be laminated with a spacer S interposed therebetween to obtain a laminated body.

[0086] (Step 7)

[0087] Impregnate a liquid component into the capacitor element. The impregnation process (the seventh process) of the liquid component includes a process of causing the first conductive polymer component to migrate to the second conductive polymer component to increase the conductive path between the second conductive polymer component and the first conductive polymer component.

[0088] By using the liquid component, the conductive polymer component is protected, and the oxidative degradation of the conductive polymer component is suppressed. The decrease in conductivity caused by the oxidative degradation of the conductive polymer component is suppressed, and the increase in ESR caused by the decrease in conductivity is suppressed. In addition, by using this liquid component, the defective part of the dielectric layer is repaired, and the increase in leakage current caused by the defect of the dielectric layer is suppressed.

[0089] (Liquid component)

[0090] The liquid component impregnated into the capacitor element can be a non-aqueous solvent or an electrolytic solution. The electrolytic solution contains a non-aqueous solvent and a solute (such as a salt described later) dissolved in the non-aqueous solvent. It should be noted that in this specification, the liquid component can be a component that is liquid at room temperature (25 °C) or a component that is liquid at the temperature during the use of the electrolytic capacitor.

[0091] The non-aqueous solvent used in the liquid component can be an organic solvent, an ionic liquid, or a protic solvent. Examples of the non-aqueous solvent include polyols such as ethylene glycol and propylene glycol, cyclic sulfones such as sulfolane, lactones such as γ-butyrolactone, 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, and formaldehyde.

[0092] In addition, as the non-aqueous solvent, a polymer-based solvent can also be used. Examples of the polymer-based solvent include polyalkylene glycols, derivatives of polyalkylene glycols, and compounds in which at least one of the hydroxyl groups in polyols is replaced by a polyalkylene glycol (including derivatives). Specifically, examples of the polymer-based solvent 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 the polymer-based solvent also 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.

[0093] From the viewpoint of suppressing the de-doping of the dopant, the liquid component can contain an acid component. As the acid component, polycarboxylic acids and monocarboxylic acids can be used.

[0094] Examples of the above polycarboxylic acids include aliphatic polycarboxylic acids ([saturated polycarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid]; [unsaturated polycarboxylic acids such as maleic acid, fumaric acid, itaconic acid]), aromatic polycarboxylic acids (such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid), and alicyclic polycarboxylic acids (such as cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, etc.).

[0095] Examples of the above monocarboxylic acids include aliphatic monocarboxylic acids (having 1 to 30 carbon atoms) ([saturated monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearic acid, behenic acid]; [unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, oleic acid]), aromatic monocarboxylic acids (such as benzoic acid, cinnamic acid, naphthoic acid), and hydroxycarboxylic acids (such as salicylic acid, mandelic acid, resorcylic acid).

[0096] Among them, maleic acid, phthalic acid, benzoic acid, pyromellitic acid, and resorcylic acid are thermally stable and are preferably used.

[0097] As the acid component, inorganic acids can also be used. Examples of representative inorganic acids include phosphoric acid, phosphorous acid, hypophosphorous acid, alkyl phosphate esters, boric acid, fluoboric acid, tetrafluoroboric acid, hexafluorophosphoric acid, benzenesulfonic acid, naphthalenesulfonic acid, etc. In addition, as the acid component, a composite compound of an organic acid and an inorganic acid can be used. Examples of such composite compounds include borodiglycolic acid, boro-oxalic acid, boro-salicylic acid, etc.

[0098] The liquid component can contain a base component while containing the acid component. The base component can be a compound having an alkyl-substituted amidino group, and for example, it can be an imidazole compound, a benzimidazole compound, an alicyclic amidine compound (pyrimidine compound, imidazoline compound), etc. Specifically, 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, 1-methylbenzimidazole are preferred. By using them, a capacitor with excellent impedance performance can be obtained.

[0099] As the base component, a quaternary salt of a compound having an alkyl-substituted amidino group can be used. Examples of such base components include imidazole compounds, benzimidazole compounds, and alicyclic amidine compounds (pyrimidine compounds, imidazoline compounds) quaternized with an alkyl or aralkyl group having 1 to 11 carbon atoms. Specifically, 1-methyl-1,8-diazabicyclo[5,4,0]undec-7-ene, 1-methyl-1,5-diazabicyclo[4,3,0]non-5-ene, 1,2,3-trimethylimidazolinium, 1,2,3,4-tetramethylimidazolinium, 1,2-dimethyl-3-ethyl-imidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2-heptylimidazolinium, 1,3-dimethyl-2-(3'-heptyl)imidazolinium, 1,3-dimethyl-2-dodecylimidazolinium, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium, 1,3-dimethylimidazolium, 1-methyl-3-ethylimidazolium, 1,3-dimethylbenzimidazolium are preferred. By using them, a capacitor with excellent impedance performance can be obtained.

[0100] In addition, as the base component, a tertiary amine can also be used. Examples of tertiary amines include trialkylamines (trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyl-n-propylamine, dimethylisopropylamine, methylethyl-n-propylamine, methylethylisopropylamine, diethyl-n-propylamine, diethylisopropylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, tri-tert-butylamine, etc.), and amines containing a phenyl group (dimethylaniline, methylethylaniline, diethylaniline, etc.). Among them, from the aspect of higher conductivity, trialkylamines are preferred, and those containing at least one selected from trimethylamine, dimethylethylamine, methyldiethylamine, and triethylamine are more preferred. In addition, as the base component, secondary amines such as dialkylamines, primary amines such as monoalkylamines, and ammonia can also be used.

[0101] The liquid component may also contain a salt of an acid component and a base component. The salt can be an inorganic salt and / or an organic salt. An organic salt is a salt in which at least one of the anion and the cation contains an organic substance. The organic salt is preferably an amine salt of an organic acid, etc. Examples of the organic salt include trimethylamine maleate, triethylamine borodisalicylate, triethylamine phthalate, ethyl dimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, mono-1,3-dimethyl-2-ethylimidazolinium phthalate, etc.

[0102] In order to suppress the de-doping of the dopant, the pH of the liquid component can be set to less than 7.0 or 5.0 or less, or can be set to 1.0 or more, or 2.0 or more. The pH can be set to 1.0 or more and less than 7.0 (for example, in the range of 2.0 to 5.0).

[0103] The liquid component preferably contains a protic solvent. By using a protic solvent, the conductive polymer layer can be significantly swollen.

[0104] The liquid component may contain a third polyol as a protic solvent. The third polyol preferably contains at least one selected from diol compounds, glycerol compounds, and sugar alcohol compounds. The third polyol may use the same compound as at least one of the first polyol and the second polyol. The first polyol to the third polyol may use the same compound.

[0105] (Others)

[0106] The manufacturing method may include a step of sealing the capacitor element impregnated with the liquid component. For example, the capacitor element and the liquid component may be housed in a bottomed outer shell, a sealing member may be disposed at the opening of the bottomed outer shell, a lateral drawing process may be performed near the open end of the bottomed outer shell, and a curling process may be performed by caulking the open end to the sealing member, and a seat plate may be disposed at the curled portion. In this way, an electrolytic capacitor can be obtained. Thereafter, the electrolytic capacitor may be aged while applying a rated voltage.

[0107] [Electrolytic Capacitor]

[0108] The electrolytic capacitor according to the embodiment of the present application includes a capacitor element and a liquid component. The capacitor element includes: an anode foil having a dielectric layer, a cathode foil, a spacer sandwiched between the anode foil and the cathode foil, a first conductive polymer component attached to the spacer, and a second conductive polymer component attached to the anode foil and the cathode foil. The first conductive polymer component has a higher solubility in water than the second conductive polymer component. That is, the adhesion of the first conductive polymer component to the surface of the spacer is lower than the adhesion of the second conductive polymer component to the surface of the electrode foil. The electrolytic capacitor can be obtained by using the manufacturing method according to the embodiment of the present application.

[0109] For the spacer attached with the first conductive polymer component that has been dried at 105°C for 30 minutes in advance, it is immersed in water at 25°C for 10 minutes, and then dried again at 105°C for 30 minutes. The mass change rate R of the spacer before and after the immersion is preferably 20% by mass or more, may be 30% by mass or more, and may be 30% by mass or more and 60% by mass or less. In this case, the adhesion of the first conductive polymer component to the surface of the spacer is low to such an extent that after the infiltration of the liquid component, the first conductive polymer component can migrate to the second conductive polymer component so as to fill the gap between the electrode foil and the spacer.

[0110] For at least one of the anode foil and the cathode foil to which the second electroconductive polymer component is attached and which has been dried at 105°C for 30 minutes, it is immersed in water at 25°C for 10 minutes, and then dried again at 105°C for 30 minutes. In this case, the mass change rate R of at least one of the anode foil and the cathode foil before and after the immersion is preferably less than 2% by mass, more preferably 1% by mass or less. In this case, the adhesion of the second electroconductive polymer component to the surface of the electrode foil is so high that the second electroconductive polymer component on the surface of the electrode foil remains firmly attached even after the infiltration of the liquid component.

[0111] The mass change rate R of the component (spacer, anode foil, cathode foil) to which the electroconductive polymer component is attached before and after immersion can be obtained as follows.

[0112] After previously drying the component at 105°C for 30 minutes, the mass M1 is measured. Then, the component is immersed in water at 25°C for 10 minutes, and then dried at 105°C for 30 minutes. The mass M2 of the dried component is measured. Using the obtained M1 and M2, the mass change rate R is obtained using the following formula (1).

[0113] Mass change rate R = {(M1 - M2) / M1} × 100 …(1)

[0114] By coating the surface of the spacer with the first treatment liquid, a first electroconductive polymer layer containing the first electroconductive polymer component is formed on the surface of the spacer. The conductivity of the first electroconductive polymer layer (first electroconductive polymer component) can be, for example, 0.1 S / cm or less, or can be 0.05 S / cm or less.

[0115] By coating the surface of the electrode foil with the second treatment liquid, a second electroconductive polymer layer containing the second electroconductive polymer component is formed on the surface of the electrode foil. The conductivity of the second electroconductive polymer layer (second electroconductive polymer component) can be 0.5 S / cm or more, or can be 3 S / cm or more, or can be 10 S / cm or more.

[0116] The conductivity of the first electroconductive polymer layer is the conductivity of the surface of a specimen obtained by coating the treatment liquid used for forming the first electroconductive polymer layer on the spacer and sufficiently drying the coating film to remove the dispersion medium (or solvent). The conductivity of the second electroconductive polymer layer is the conductivity of the surface of a specimen obtained by coating the treatment liquid used for forming the second electroconductive polymer layer on the electrode foil and sufficiently drying the coating film to remove the dispersion medium (or solvent). This conductivity can be obtained in accordance with the "Test Method for Resistivity of Conductive Plastics by the Four-Probe Method" of Japanese Industrial Standards (JIS K 7194). It should be noted that a low resistivity meter and PSP probes, ESP probes, etc. can be used as the measuring instrument.

[0117] The mass of the liquid component is preferably 20 times or more the total mass of the first conductive polymer component and the second conductive polymer component (the second A conductive polymer component and the second B conductive polymer component). The mass of the liquid component is more preferably 80 times or more the total mass of the first conductive polymer component and the second conductive polymer component (the second A conductive polymer component and the second B conductive polymer component). In this case, the liquid component can be sufficiently infiltrated between the spacer having the first conductive polymer component attached to its surface and the electrode foil having the second conductive polymer component attached to its surface, and the first conductive polymer component can migrate to the second conductive polymer component. In addition, the conductive polymer component can be sufficiently protected by the liquid component.

[0118] The capacitor element may be a laminate formed by laminating in order an anode foil having the second A conductive polymer component attached thereto, a spacer having the first conductive polymer component attached thereto, and a cathode foil having the second B conductive polymer component attached thereto. Alternatively, the capacitor element may be a wound body formed by winding an anode foil having the second A conductive polymer component attached thereto and a cathode foil having the second B conductive polymer component attached thereto with a spacer having the first conductive polymer component attached thereto interposed therebetween. The electrolytic capacitor may include one capacitor element or a plurality of capacitor elements.

[0119] Here, Figure 1 is a cross-sectional view schematically showing an electrolytic capacitor according to an embodiment of the present application. Figure 2 is a perspective view showing a part of the wound body unfolded.

[0120] In the electrolytic capacitor 200, a wound body 100 is provided as a capacitor element. The anode foil 10 having the second A conductive polymer component attached thereto and the cathode foil 20 having the second B conductive polymer component attached thereto are wound with a spacer 30 having the first conductive polymer component attached thereto interposed between the anode foil 10 and the cathode foil 20, thereby forming the wound body 100. A liquid component (not shown) is infiltrated in the wound body 100.

[0121] One end portions of lead terminals 50A and 50B are respectively connected to the anode foil 10 and the cathode foil 20, and the wound body 100 is formed while winding the lead terminals 50A and 50B. Lead wires 60A and 60B are respectively connected to the other end portions of the lead terminals 50A and 50B.

[0122] A winding fixing tape 40 is disposed on the outer surface of the cathode foil 20 located on the outermost layer of the wound body 100, and the end portion of the cathode foil 20 is fixed by the winding fixing tape 40. It should be noted that when the anode foil 10 is prepared by cutting a large-sized foil, the wound body 100 can be further subjected to formation treatment in order to provide a dielectric layer on the cut surface.

[0123] The electrolytic capacitor 200 includes a sealing member 212 that closes the opening of the bottomed case 211 and a base plate 213 that covers the sealing member 212. The wound body 100 is housed in the bottomed case 211 such that the lead wires 60A and 60B are located on the opening side of the bottomed case 211. The lead wires 60A and 60B are led out from the sealing member 212 and penetrate through the base plate 213. As the material of the bottomed case 211, metals such as aluminum, stainless steel, copper, iron, brass, or their alloys can be used.

[0124] The sealing member 212 is disposed at the opening of the bottomed case 211 that houses the wound body 100, and the opening end of the bottomed case 211 is caulked tightly to the sealing member 212 and crimped. The base plate 213 is disposed at the crimped portion, whereby the wound body 100 is sealed within the bottomed case 211. The sealing member 212 may be any insulating material, and an elastomer is preferred. As the elastomer, materials with excellent heat resistance such as silicone rubber and fluororubber are preferred.

[0125] [Embodiment]

[0126] Hereinafter, the present application will be described in further detail based on the embodiments. However, the present application is not limited to the embodiments. Electrolytic capacitors of the embodiments and comparative examples are manufactured using the following steps.

[0127] (Preparation of Constituent Parts)

[0128] An aluminum foil (thickness: 100 μm) is subjected to an etching treatment to roughen the surface of the aluminum foil. A dielectric layer is formed by subjecting the roughened surface of the aluminum foil to a formation treatment. In this way, an anode foil having a dielectric layer formed on the surface is obtained.

[0129] An aluminum foil (thickness: 50 μm) is subjected to an etching treatment to roughen the surface of the aluminum foil, thereby obtaining a cathode foil.

[0130] As the spacer, a non-woven fabric (thickness: 50 μm) is prepared. The non-woven fabric is composed of 50% by mass of synthetic fibers (25% by mass of polyester fibers and 25% by mass of aramid fibers) and 50% by mass of cellulose, and contains polyacrylamide as a paper strengthening agent. The density of the non-woven fabric is 0.35 g / cm 3 .

[0131] (Preparation of the First Treatment Liquid)

[0132] A first treatment liquid containing a first conductive polymer component, water, and a first polyol is prepared. The contents of the respective components in the first treatment liquid are set to the values shown in Table 1.

[0133] (Preparation of the second A treatment liquid)

[0134] A second A treatment liquid containing a second A conductive polymer component, water, and a second A polyol is prepared. The contents of the respective components in the second A treatment liquid are set to the values shown in Table 2.

[0135] (Preparation of the second B treatment liquid)

[0136] A second B treatment liquid containing a second B conductive polymer component, water, and a second B polyol is prepared. The contents of the respective components in the second B treatment liquid are set to the values shown in Table 3.

[0137] As the first conductive polymer component, the second A conductive polymer component, and the second B conductive polymer component, poly(3,4-ethylenedioxythiophene) (PEDOT) doped with polystyrene sulfonic acid (PSS) (hereinafter referred to as "PEDOT / PSS") is used respectively.

[0138] As the first polyol, the second A polyol, and the second B polyol, ethylene glycol is used respectively.

[0139] (Formation of the conductive polymer layer)

[0140] Using a gravure coater, the first treatment liquid is coated on both sides of the spacer, and the coating film is dried to form a first conductive polymer layer. The drying treatment is performed by heating the spacer coated with the first treatment liquid at 125 °C for 5 minutes. In this way, a spacer S (with the first conductive polymer component attached) having a first conductive polymer layer formed on its surface is produced. Using the first treatment liquid shown in Table 1, S1 to S7 are produced as the spacer S.

[0141] [Table 1]

[0142]

[0143] Using a gravure coater, the second A treatment liquid is coated on both sides of the anode foil having a dielectric layer, and the coating film is dried to form a second A conductive polymer layer. The drying treatment is performed by heating the anode foil coated with the second A treatment liquid at 125 °C for 5 minutes. In this way, an anode foil P (with the second A conductive polymer component attached) having a second A conductive polymer layer formed on its surface is produced. Using the second A treatment liquid shown in Table 2, P1 to P7 are produced as the anode foil P.

[0144] [Table 2]

[0145]

[0146] Using the same method as in the case of the anode foil, a 2B conductive polymer layer is formed on both sides of the cathode foil using the 2B treatment liquid. In this way, a cathode foil N (attached with the 2B conductive polymer component) having a 2B conductive polymer layer formed on its surface is produced. Using the 2B treatment liquid shown in Table 3, N1 to N7 are produced as the cathode foil N.

[0147] [Table 3]

[0148]

[0149] (Fabrication of capacitor element)

[0150] The anode foil P, the cathode foil N, and the spacer S are respectively cut into a predetermined size. An anode lead joint and a cathode lead joint are connected to the anode foil P and the cathode foil N. Then, the anode foil P and the cathode foil N are wound with the spacer S interposed therebetween. At the end of each lead joint protruding from the wound body, an anode lead and a cathode lead are respectively connected. The obtained wound body is subjected to a forming treatment again, and a dielectric layer is formed on the end face of the anode foil (aluminum foil). The end of the outer surface of the wound body is fixed with a winding fixing tape. In this way, a capacitor element is obtained.

[0151] (Infiltration of liquid component)

[0152] Triethylamine phthalate is dissolved in ethylene glycol at a concentration of 25% by mass to prepare an electrolytic solution. In a reduced-pressure atmosphere (40 kPa), the capacitor element is immersed in the electrolytic solution for 5 minutes. In this way, the electrolytic solution is infiltrated into the capacitor element (laminated body).

[0153] (Sealing of capacitor element)

[0154] The capacitor element infiltrated with the electrolytic solution is sealed to produce an electrolytic capacitor as shown in Figure 1 . Thereafter, aging is performed at 95 °C for 90 minutes while applying a voltage. In this way, an electrolytic capacitor is obtained.

[0155] In the fabrication of the above capacitor element, using the components (spacer S, anode foil P, cathode foil N) shown in Tables 4 to 7, an electrolytic capacitor is obtained. It should be noted that A1 to A4 in Table 4, A11 to A12 in Table 5, and A21 to 22 in Table 6 are examples, and B1 to B3 in Table 4, B11 to B14 in Table 5, B21 to B24 in Table 6, and B31 to B37 in Table 7 are comparative examples.

[0156] [Table 4]

[0157]

[0158] [Table 5]

[0159]

[0160] [Table 6]

[0161]

[0162] [Table 7]

[0163]

[0164] [Evaluation of Each Component Part]

[0165] (Mass Change Rate of Each Component Part Before and After Immersion in Water)

[0166] For each component part of the anode foil P, cathode foil N, and spacer S, the mass change rate R before and after immersion in water was obtained by the method described above. The obtained mass change rate R is shown in Tables 1 to 3.

[0167] In S1 to S4 prepared using the first treatment liquid with the content of the first polyol less than 10% by mass (5% by mass or less), compared with S5 to S7 prepared using the first treatment liquid with the content of the first polyol of 10% by mass or more, the mass change rate R is as large as 20% by mass or more, indicating that the first conductive polymer component is likely to migrate to the second A conductive polymer component and the second B conductive polymer component when infiltrating the liquid component into the capacitor element.

[0168] In P5 to P7 prepared using the second A treatment liquid with the content of the second A polyol of 10% by mass or more, compared with P1 to P4 prepared using the second A treatment liquid with the content of the second A polyol less than 10% by mass, the mass change rate R is less than 2% by mass, indicating that the adhesion of the second A conductive polymer component is high.

[0169] In N5 to N7 prepared using the second B treatment liquid with the content of the second B polyol of 10% by mass or more, compared with N1 to N4 prepared using the second B treatment liquid with the content of the second B polyol less than 10% by mass, the mass change rate R is as small as less than 2% by mass, indicating that the adhesion of the second B conductive polymer component is high.

[0170] In addition, in S1 to S4, in the first treatment liquid, the mass of the first polyol is less than 5 times the mass of the first conductive polymer component. In P5 to P7, in the second A treatment liquid, the mass of the second A polyol is 5 times or more the mass of the second A conductive polymer component. In N5 to N7, in the second B treatment liquid, the mass of the second B polyol is 5 times or more the mass of the second B conductive polymer component.

[0171] (Electric conductivity of the conductive polymer layer formed on the surface of each component part)

[0172] In addition, by using the method described above, the electric conductivity of the conductive polymer layer formed on the surface of the component part is obtained. The obtained electric conductivity is shown in Tables 1 to 3.

[0173] Among S1 to S4 produced using the first treatment liquid with the content of the first polyol less than 10% by mass (5% by mass or less), compared with S5 to S7 produced using the first treatment liquid with the content of the first polyol of 10% by mass or more, the electric conductivity of the first conductive polymer layer formed on the surface of the spacer is low, being 0.1 S / cm or less.

[0174] Among P5 to P7 produced using the 2A treatment liquid with the content of the 2A polyol of 10% by mass or more, compared with P1 to P4 produced using the 2A treatment liquid with the content of the 2A polyol less than 10% by mass, the electric conductivity of the 2A conductive polymer layer formed on the surface of the anode foil is high, being 0.5 S / cm or more.

[0175] Among N5 to N7 produced using the 2B treatment liquid with the content of the 2B polyol of 10% by mass or more, compared with N1 to N4 produced using the 2B treatment liquid with the content of the 2B polyol less than 10% by mass, the electric conductivity of the 2B conductive polymer layer formed on the surface of the cathode foil is high, being 0.5 S / cm or more.

[0176] [Evaluation of electrolytic capacitor: Measurement of ESR]

[0177] In an environment of 20°C, using an LCR tester for four-terminal measurement, the ESR (mΩ) of the electrolytic capacitor at frequencies of 100 kHz and 120 Hz is measured. The measurement results are shown in Tables 4 to 7.

[0178] Among A1 to A4, A11 to A12, and A21 to A22, compared with B1 to B3, B11 to B13, B21 to B23, and B31 to B37, low ESR is obtained in any case in the high-frequency region and the low-frequency region. Among A1 to A4, A11 to A12, and A21 to A22, spacers S produced using the first treatment liquid with the content of the first polyol less than 10% by mass, anode foils P produced using the second treatment liquid with the content of the second polyol of 10% by mass or more, and cathode foils N are used.

[0179] It should be noted that among A1 to A4, A11 to A12, and A21 to A22, the mass of the liquid component is 20 times or more the total mass of the first conductive polymer component, the 2A conductive polymer component, and the 2B conductive polymer component.

[0180] [Supplementary Note]

[0181] The following technology is disclosed according to the description of the above embodiments.

[0182] (Technology 1)

[0183] A method for manufacturing an electrolytic capacitor, the manufacturing method comprising:

[0184] A step of preparing an anode foil, a cathode foil, and a spacer having a dielectric layer;

[0185] A step of preparing a first treatment liquid containing a first conductive polymer component;

[0186] A step of preparing a second treatment liquid containing a second conductive polymer component;

[0187] A step of applying the first treatment liquid to the spacer to attach the first conductive polymer component;

[0188] A step of applying the second treatment liquid to at least one of the anode foil and the cathode foil to attach the second conductive polymer component;

[0189] After the step of attaching the second conductive polymer component, a step of sequentially laminating the anode foil, the spacer having the first conductive polymer component attached thereto, and the cathode foil to fabricate a capacitor element; and

[0190] A step of impregnating a liquid component into the capacitor element,

[0191] The first treatment liquid contains a first polyol or substantially does not contain a first polyol,

[0192] The content of the first polyol in the first treatment liquid is 0% by mass or more and less than 10% by mass,

[0193] The second treatment liquid contains a second polyol,

[0194] The content of the second polyol in the second treatment liquid is 10% by mass or more.

[0195] (Technology 2)

[0196] According to the method for manufacturing an electrolytic capacitor described in Technology 1, wherein the step of impregnating the liquid component includes: a step of causing the first conductive polymer component to migrate to the second conductive polymer component to increase the conductive path between the second conductive polymer component and the first conductive polymer component.

[0197] (Technology 3)

[0198] According to the method for manufacturing an electrolytic capacitor described in Technology 1 or 2, wherein the first polyol and the second polyol each contain at least one selected from the group consisting of diol compounds, glycerol compounds, and sugar alcohol compounds.

[0199] (Technology 4)

[0200] According to the method for manufacturing an electrolytic capacitor described in any one of Technologies 1 to 3, wherein the liquid component contains a third polyol.

[0201] (Technology 5)

[0202] According to the method for manufacturing an electrolytic capacitor described in Technology 4, wherein the third polyol contains at least one selected from the group consisting of diol compounds, glycerol compounds, and sugar alcohol compounds.

[0203] (Technology 6)

[0204] According to the method for manufacturing an electrolytic capacitor described in any one of Technologies 1 to 5, wherein the liquid component contains an amine salt of an organic acid.

[0205] (Technology 7)

[0206] According to the method for manufacturing an electrolytic capacitor described in any one of Technologies 1 to 6, wherein in the first treatment liquid, the mass of the first polyol is less than 5 times the mass of the first conductive polymer component.

[0207] (Technology 8)

[0208] According to the method for manufacturing an electrolytic capacitor described in any one of Technologies 1 to 7, wherein in the second treatment liquid, the mass of the second polyol is 5 times or more and 25 times or less the mass of the second conductive polymer component.

[0209] (Technology 9)

[0210] An electrolytic capacitor comprising a capacitor element and a liquid component,

[0211] The capacitor element includes:

[0212] An anode foil having a dielectric layer,

[0213] A cathode foil,

[0214] A spacer interposed between the anode foil and the cathode foil,

[0215] A first conductive polymer component attached to the spacer, and

[0216] A second conductive polymer component attached to at least one of the anode foil and the cathode foil,

[0217] The above-described first conductive polymer component has a higher solubility in water than the above-described second conductive polymer component.

[0218] (Technology 10)

[0219] Regarding the electrolytic capacitor described in Technology 9, when the spacer attached with the above-described first conductive polymer component, which has been previously dried at 105°C for 30 minutes, is immersed in water at 25°C for 10 minutes and then dried again at 105°C for 30 minutes, the mass change rate of the spacer before and after the immersion is 20% by mass or more.

[0220] When at least one of the above-described anode foil and the above-described cathode foil attached with the above-described second conductive polymer component, which has been previously dried at 105°C for 30 minutes, is immersed in water at 25°C for 10 minutes and then dried again at 105°C for 30 minutes, the mass change rate of at least one of the above-described anode foil and the above-described cathode foil before and after the immersion is less than 2% by mass.

[0221] (Technology 11)

[0222] Regarding the electrolytic capacitor described in Technology 9 or 10, the conductivity of the above-described first conductive polymer component is 0.1 S / cm or less.

[0223] The conductivity of the above-described second conductive polymer component is 0.5 S / cm or more.

[0224] (Technology 12)

[0225] Regarding the electrolytic capacitor described in Technology 9, the mass of the above-described liquid component is 20 times or more the total mass of the above-described first conductive polymer component and the above-described second conductive polymer component.

[0226] (Technology 13)

[0227] A first treatment liquid is coated on a spacer constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component.

[0228] The above-described first treatment liquid contains a first conductive polymer component and contains a first polyol or substantially does not contain a first polyol.

[0229] The content of the above-described first polyol in the above-described first treatment liquid is 0% by mass or more and less than 10% by mass.

[0230] The first conductive polymer component attached to the spacer by coating the first treatment liquid migrates to other adjacent conductive polymer components when the liquid component is infiltrated into the capacitor element.

[0231] (Technology 14)

[0232] A second treatment liquid, which is used together with the first treatment liquid described in Technology 13, is applied to at least one of the anode foil and the cathode foil constituting the capacitor element of an electrolytic capacitor including a capacitor element and a liquid component.

[0233] The above-mentioned second treatment liquid contains a second conductive polymer component and a second polyol.

[0234] The content of the above-mentioned second polyol in the above-mentioned second treatment liquid is 10% by mass or more.

[0235] Industrial applicability

[0236] The method for manufacturing an electrolytic capacitor of the present application can be suitably used for electrolytic capacitors that require low ESR.

[0237] Explanation of reference numerals

[0238] 10 Anode foil, 20 Cathode foil, 30 Spacer, 40 Winding fixing tape, 50A, 50B Lead connectors, 60A, 60B Leads, 100 Winding body, 200 Electrolytic capacitor, 211 Bottomed case, 212 Sealing member, 213 Base plate.

Claims

1. A method for manufacturing an electrolytic capacitor, the manufacturing method comprising: a step of preparing an anode foil, a cathode foil, and a spacer having a dielectric layer; a step of preparing a first treatment liquid containing a first conductive polymer component; a step of preparing a second treatment liquid containing a second conductive polymer component; a step of applying the first treatment liquid to the spacer to attach the first conductive polymer component; a step of applying the second treatment liquid to at least one of the anode foil and the cathode foil to attach the second conductive polymer component; a step of laminating the anode foil, the spacer having the first conductive polymer component attached thereto, and the cathode foil in sequence to produce a capacitor element after the step of attaching the second conductive polymer component; and a step of impregnating a liquid component into the capacitor element, the first treatment liquid contains a first polyol or substantially does not contain a first polyol, the content of the first polyol in the first treatment liquid is 0% by mass or more and less than 10% by mass, the second treatment liquid contains a second polyol, the content of the second polyol in the second treatment liquid is 10% by mass or more.

2. The method for manufacturing an electrolytic capacitor according to claim 1, wherein the step of impregnating the liquid component includes: a step of causing the first conductive polymer component to migrate to the second conductive polymer component to increase the conductive path between the second conductive polymer component and the first conductive polymer component.

3. The method for manufacturing an electrolytic capacitor according to claim 1, wherein each of the first polyol and the second polyol contains at least one selected from the group consisting of diol compounds, glycerol compounds, and sugar alcohol compounds.

4. The method for manufacturing an electrolytic capacitor according to claim 1, wherein the liquid component contains a third polyol.

5. The method for manufacturing an electrolytic capacitor according to claim 4, wherein the third polyol contains at least one selected from the group consisting of diol compounds, glycerol compounds, and sugar alcohol compounds.

6. The method for manufacturing an electrolytic capacitor according to claim 4, wherein the liquid component contains an amine salt of an organic acid.

7. The method for manufacturing an electrolytic capacitor according to claim 1, wherein in the first treatment liquid, the mass of the first polyol is less than 5 times the mass of the first conductive polymer component.

8. The method for manufacturing an electrolytic capacitor according to claim 1, wherein in the second treatment liquid, the mass of the second polyol is 5 times or more and 25 times or less the mass of the second conductive polymer component.

9. An electrolytic capacitor, comprising a capacitor element and a liquid component, the capacitor element comprising: an anode foil having a dielectric layer, a cathode foil, a spacer sandwiched between the anode foil and the cathode foil, a first conductive polymer component attached to the spacer, and a second conductive polymer component attached to at least one of the anode foil and the cathode foil, the first conductive polymer component has a higher solubility in water than the second conductive polymer component.

10. The electrolytic capacitor according to claim 9, wherein, when the spacer attached with the first conductive polymer component which has been dried at 105 °C for 30 minutes in advance is immersed in water at 25 °C for 10 minutes and then dried at 105 °C for 30 minutes again, the mass change rate R of the spacer before and after the immersion is 20 mass% or more, when at least one of the anode foil and the cathode foil attached with the second conductive polymer component which has been dried at 105 °C for 30 minutes in advance is immersed in water at 25 °C for 10 minutes and then dried at 105 °C for 30 minutes again, the mass change rate R of at least one of the anode foil and the cathode foil before and after the immersion is less than 2 mass%.

11. The electrolytic capacitor according to claim 9, wherein, the conductivity of the first conductive polymer component is 0.1 S / cm or less, the conductivity of the second conductive polymer component is 0.5 S / cm or more.

12. The electrolytic capacitor according to claim 9, wherein, the mass of the liquid component is 20 times or more the total mass of the first conductive polymer component and the second conductive polymer component.

13. A first treatment liquid which is coated on a spacer constituting a capacitor element of an electrolytic capacitor including a capacitor element and a liquid component, the first treatment liquid contains a first conductive polymer component and contains a first polyol or substantially does not contain a first polyol, the content of the first polyol in the first treatment liquid is 0 mass% or more and less than 10 mass%, the first conductive polymer component attached to the spacer by coating the first treatment liquid on the spacer migrates to an adjacent other conductive polymer component when the liquid component is infiltrated into the capacitor element.

14. A second treatment liquid which is used together with the first treatment liquid according to claim 13, the second treatment liquid is coated on at least one of an anode foil and a cathode foil constituting the capacitor element of an electrolytic capacitor including a capacitor element and a liquid component, the second treatment liquid contains a second conductive polymer component and a second polyol, the content of the second polyol in the second treatment liquid is 10 mass% or more.

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