WO2025192529A1 - Condensateur électrolytique et procédé de fabrication - Google Patents

Condensateur électrolytique et procédé de fabrication

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Publication number
WO2025192529A1
WO2025192529A1 PCT/JP2025/008827 JP2025008827W WO2025192529A1 WO 2025192529 A1 WO2025192529 A1 WO 2025192529A1 JP 2025008827 W JP2025008827 W JP 2025008827W WO 2025192529 A1 WO2025192529 A1 WO 2025192529A1
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WO
WIPO (PCT)
Prior art keywords
electrolyte
elastomer
electrolytic capacitor
acid
examples
Prior art date
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Pending
Application number
PCT/JP2025/008827
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English (en)
Japanese (ja)
Inventor
秀明 高橋
一平 中村
哲生 前田
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Nippon Chemi Con Corp
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Nippon Chemi Con Corp
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Publication of WO2025192529A1 publication Critical patent/WO2025192529A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/004—Details
    • H01G9/08—Housing; Encapsulation
    • H01G9/10—Sealing, e.g. of lead-in wires
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/145—Liquid electrolytic capacitors

Definitions

  • the present invention relates to an electrolytic capacitor that obtains capacitance through the dielectric polarization of a dielectric film and stores and discharges electric charge, and to a manufacturing method for such an electrolytic capacitor.
  • Electrolytic capacitors that use valve action metals such as tantalum or aluminum can achieve a small size and large capacitance by enlarging the surface area of the dielectric by sintering the valve action metal used as the anode counter electrode into the form of a sintered body or etched foil. This type of electrolytic capacitor fills the gaps with electrolyte to ensure close contact between the anode's dielectric film and the counter electrode.
  • the electrolyte comes into direct contact with the dielectric film and acts as a true cathode, while also repairing the dielectric film. However, over time, the electrolyte evaporates and escapes to the outside of the electrolytic capacitor. As a result, the capacitance of the electrolytic capacitor decreases over time as it dries out, eventually reaching the end of its life.
  • the capacitor element is housed in a bottomed outer case, and the opening of the outer case is sealed with a sealant.
  • This sealant is tightly attached to the case opening by crimping, and is made of an elastic material with appropriate hardness to improve sealing performance.
  • the sealant contains an elastomer such as butyl rubber. The elastomer is created by vulcanization to cause a cross-linking reaction.
  • the electrolyte is not completely contained within the case, but rather gradually permeates the sealing material and volatilizes out of the electrolytic capacitor. Therefore, it has been proposed to use a solvent with a high boiling point for the electrolyte (see, for example, Patent Document 1).
  • Known high-boiling-point solvents include gamma-butyrolactone, which has a boiling point of 203°C; butanediol, which has a boiling point of 230°C; sulfolane, which has a boiling point of 285°C; ethylene glycol, which has a boiling point of 198°C; and diethylene glycol, which has a boiling point of 244°C.
  • electrolytic capacitors have been required to perform well in high-temperature environments, such as those at 170°C, such as those used in automobiles. Specifically, electrolytic capacitors are required to have a long lifespan, maintaining a certain level of capacitance for long periods of time, even in high-temperature environments.
  • the inventors have confirmed that even if an electrolyte solution is formulated using a solvent with a high boiling point above 170°C, evaporation of the electrolyte solution cannot be suppressed in such high-temperature environments, resulting in a decrease in the capacitance of the electrolytic capacitor.
  • the present invention has been proposed to solve the above problems, and its purpose is to provide an electrolytic capacitor and a manufacturing method that suppresses capacitance reduction even in high-temperature environments.
  • the electrolytic capacitor of this embodiment comprises a capacitor element having an anode body, a cathode body, an electrolytic solution, and a solid electrolyte, a case that houses the capacitor element, and a sealing body that seals the case, wherein the sealing body has an elastic body containing an elastomer, the elastomer containing butyl rubber and comprising 31 wt% or more of the elastomer relative to the elastic body, and the electrolytic solution contains 40 wt% or more of glycerin, diglycerin, or both in the solvent of the electrolytic solution.
  • the content of the elastomer may be 36 wt% or less relative to the elastic body.
  • the carbon may be carbon black with a dibutyl phthalate absorption of 80 ml/100 g or less.
  • the electrolyte may have an electrolyte loading coefficient R, expressed by the following formula (Equation 1), of 3.93 mg ⁇ mm/mm 2 or more. (Equation 1)
  • This capacitor element is housed in a case.
  • the case is made of aluminum, an aluminum alloy containing aluminum or manganese, or stainless steel, and is, for example, a cylinder with a bottom and an open end.
  • a pressure release valve may be formed at the bottom of the case, which opens when the internal pressure of the case exceeds a set pressure.
  • the opening of the case is sealed by a sealing body.
  • the sealing body is attached to the opening of the case by crimping, and the crimping process bends and crushes the opening of the case inward, tightly sealing the sealing body.
  • the sealing body has an elastic body primarily made of elastomer.
  • the elastic body contains at least butyl rubber as the elastomer.
  • Butyl rubber is also called isobutylene isoprene rubber.
  • regular butyl is preferred as the butyl rubber.
  • the content of the elastomer containing butyl rubber in the elastic body is 31 wt% or more.
  • the electrolyte contains 40 wt% or more of glycerin, diglycerin, or both, based on the total amount of solvent in the electrolyte, and a solid electrolyte is used in addition to the electrolyte.
  • the mechanism of thermal oxidative degradation of the sealant's elastomer is as follows: First, the C-H bonds of the elastomer molecules on the exterior of the case are cleaved, generating radicals. First, these radicals attack other C-H bonds in the elastomer molecules, promoting further cleavage. Second, oxygen is added to these radicals, generating peroxides. These peroxides decompose under heat, accelerating the generation of radicals, which then attack other C-H bonds in the elastomer molecules, promoting further cleavage.
  • the electrolyte causes swelling of the elastic material inside the seal case. This causes contraction and expansion in areas within the seal, leading to cracks in the seal's elastic material.
  • the electrolyte evaporates through the cracks, reducing the capacitance of the electrolytic capacitor.
  • butyl rubber is resistant to electrolyte penetration, suppressing swelling of the inside of the elastomer case. Therefore, in elastomers containing butyl rubber, the difference in volume change between the inside of the case, which swells in response to electrolyte penetration, and the outside of the case, which shrinks due to thermal oxidative degradation, is smaller. Furthermore, when the elastomer content in the elastomer is 31 wt% or more, the bending strain change rate of the elastomer remains within -30%, even when exposed to high-temperature environments for long periods of time. Limiting the bending strain change rate of the elastomer to a decrease of 30% or less maintains flexibility and makes the elastomer less susceptible to cracking. This makes it possible to suppress the evaporation of electrolyte through cracks.
  • the bending strain change rate indicates the change in bending test results before and after long-term exposure to a high-temperature environment.
  • the temperature and time for which the elastic body is exposed in the bending test are 170°C and 1,000 hours.
  • the bending test is a three-point bending test in accordance with JIS K7171. An elastic body test piece measuring 2 mm thick, 40 mm long, and 25 mm wide is prepared and placed on a support with a support distance of 32 mm. In a temperature environment of 170°C, a force is applied to the center of the test piece using an indenter at a test speed of 1 mm/min. The bending strain is then measured until the test piece cracks.
  • the bending strain (%) after long-term exposure to a high-temperature environment is subtracted from the bending strain (%) before long-term exposure to a high-temperature environment, and the percentage of this difference compared to the bending strain (%) before long-term exposure to a high-temperature environment is taken as the bending strain change rate.
  • the solid electrolyte reduces the high resistivity caused by the high viscosity of glycerins, lowering the internal resistance of the electrolytic capacitor.
  • the solid electrolyte is a conductive polymer.
  • the conductivity of the solid electrolyte layer decreases, and the canceling effect of glycerin and diglycerin on the resistivity is weakened.
  • this electrolytic capacitor uses a solid electrolyte in addition to the electrolytic solution.
  • the elastomer of the sealing body may contain, in addition to butyl rubber, elastomers such as ethylene propylene diene rubber (also known as EPDM), styrene butadiene rubber, isoprene rubber, fluororubber, acrylic rubber, natural rubber, or a mixture of these, as long as the butyl rubber content exceeds 50 wt% of the total elastomers contained in the elastomer.
  • the elastomer content in the elastomer is preferably 36 wt% or less.
  • the elastomer of the present invention refers to a polymeric substance exhibiting rubber elasticity and is thermosetting.
  • Butyl rubber is preferably produced by vulcanization.
  • vulcanization include resin vulcanization, sulfur vulcanization, and quinoid vulcanization.
  • vulcanizing agents include alkylphenol resins such as alkylphenol formaldehyde resins, quinoids, and sulfur.
  • crosslinking accelerators include zinc oxide, magnesium oxide, lead peroxide, dibenzothiazyl, disulfides, 1,2-polybutadiene, triallyl cyanurate, metal salts of methacrylic acid and acrylic acid, and ester stearic acid N,N'-metaphenyl dimaleic acid.
  • butyl rubber is preferably crosslinked with alkylphenol resins, which inhibits cleavage of the butyl rubber.
  • the elastomer be a blended rubber made by crosslinking butyl rubber and ethylene propylene rubber through resin vulcanization. This suppresses evaporation of the electrolyte more than when butyl rubber and ethylene propylene rubber are vulcanized separately and then mixed.
  • This blended rubber is made by mixing unvulcanized butyl rubber and unvulcanized ethylene propylene rubber, then adding a resin vulcanizing agent to the mixture, and then pressurizing and heating it.
  • this blended rubber is made by adding unvulcanized butyl rubber, unvulcanized ethylene propylene rubber, and a resin vulcanizing agent, and then pressurizing and heating it.
  • the elastic body may also contain carbon and inorganic fillers.
  • carbon and inorganic fillers make the butyl rubber less likely to cleave, preventing it from softening.
  • examples of carbon include carbon black
  • examples of inorganic fillers include talc, mica, silica, kaolin, titania, alumina, and mixtures of these.
  • the carbon and inorganic filler be contained in a total proportion of 50 wt% or more and 60 wt% or less of the entire elastomer. If the total content of carbon and inorganic filler is 50 wt% or more of the entire elastomer, the elastomer will have even better strength, which will contribute to a lower rate of change in bending strain after exposure to a high-temperature environment. Furthermore, if the total content of carbon and inorganic filler is 60 wt% or less of the entire elastomer, the elastomer will have good flexibility and cracking of the elastomer can be suppressed.
  • the carbon is preferably carbon black with a dibutyl phthalate absorption of 80 ml/100 g or more.
  • Dibutyl phthalate absorption is also called DBP absorption or DBP oil absorption.
  • Carbon black exists as agglomerates in which particles are strongly adhered to one another; these agglomerates are called aggregates and have a structure similar to that of a bunch of grapes.
  • Dibutyl phthalate absorption indicates the ability of the voids within this structure to absorb dibutyl phthalate. In other words, it is an index of the degree of development of the carbon black structure. This dibutyl phthalate absorption can be measured, for example, according to the method for determining oil absorption in JIS standard JIS K 6217-4.
  • the carbon contained in the elastic body of the sealing body is carbon black with a structure that results in a dibutyl phthalate absorption of 80 ml/100 g or less, it not only contributes to a reduction in the rate of change in bending strain after exposure to a high-temperature environment, thereby suppressing the decrease in capacitance, but also significantly reduces the leakage current of the electrolytic capacitor. While this is speculation and not limited to this mechanism, the mechanism behind the leakage current suppression effect is speculated to be as follows:
  • the carbon black has a structure that results in a dibutyl phthalate absorption of 80 ml/100 g or less, the frequency of contact between carbon black aggregates will be kept low, and carbon black linkages will not occur or will be reduced. In other words, no conductive circuits will be formed within the sealant, or the number of parallel conductive circuits within the sealant will be kept low, maintaining the sealant's electrical resistance high. Therefore, not only can the capacitance of the electrolytic capacitor be kept low, but it is presumed that the leakage current of the electrolytic capacitor will also be suppressed. Furthermore, suppressing the leakage current of the electrolytic capacitor will further suppress the decrease in capacitance over time.
  • the sealing body may also be a laminate of an elastomer and a rigid substrate, or the rigid substrate may be enclosed within the elastomer.
  • the rigid substrate is a synthetic resin plate, ceramic plate, or metal plate. Synthetic resin plates are made of, for example, phenolic resin, epoxy resin, or polyethylene sulfide resin. Various resins can be used, including epoxy resin, fluororesin, acrylic resin, polyimide resin, silicone resin, phenolic resin, melamine resin, urethane resin, and unsaturated polyester resin.
  • Metal plates are made of, for example, aluminum, aluminum alloys containing aluminum or manganese, or stainless steel.
  • the rigid substrate improves the airtightness inside the electrolytic capacitor and protects the elastomer from the electrolyte and heat.
  • Monohydric alcohols include ethanol, propanol, butanol, pentanol, hexanol, cyclobutanol, cyclopentanol, cyclohexanol, and benzyl alcohol.
  • Polyhydric alcohols and oxyalcohol compounds include ethylene glycol, propylene glycol, methyl cellosolve, ethyl cellosolve, methoxypropylene glycol, and dimethoxypropanol.
  • Solvents added other than glycerin and diglycerin are preferably ethylene glycol, sulfolane, or both.
  • the boiling point of ethylene glycol is 198°C.
  • the boiling point of sulfolane is 285°C. Therefore, an electrolyte containing ethylene glycol and sulfolane has an evaporation suppression effect.
  • the concentration of glycerins can be reduced, which reduces the viscosity of the entire electrolyte and the specific resistance of the electrolytic capacitor.
  • the content of glycerins may be 100 wt% or less of the total amount of solvent in the electrolyte, and is preferably 98 wt% or less.
  • the weight of the initial electrolyte is the weight of the electrolyte filled into the electrolytic capacitor during its manufacturing process.
  • This initial electrolyte can be extracted by removing the capacitor elements from an unused electrolytic capacitor and using a centrifuge or similar device. In other words, the amount of water that was mixed in during the manufacturing process of the electrolytic capacitor is also added to the weight of the initial electrolyte.
  • the thickness of the sealing body is the length along the winding axis of the capacitor element, and is the distance the electrolyte inside the electrolytic capacitor must pass through before escaping to the outside.
  • the sealing surface area of the sealing body is the area of the plane extending in a direction perpendicular to the winding axis of the capacitor element, and is the area exposed to the inside of the electrolytic capacitor that the electrolyte inside the electrolytic capacitor can pass through to escape to the outside.
  • this electrolyte loading coefficient R is 3.93 mg mm/mm2 or more , not only is the electrolytic capacitor prevented from decreasing in capacitance due to exposure to a high-temperature environment, but also an increase in resistance at low frequencies, i.e., dielectric loss tangent (tan ⁇ ), can be suppressed.
  • the reason why an increase in tan ⁇ is suppressed when the electrolyte loading coefficient R is 3.93 mg mm/mm2 or more is as follows. That is, first, when the electrolyte evaporates, the amount of electrolyte around the conductive polymer decreases, making it easier for oxygen to reach the conductive polymer without being trapped by the electrolyte. Therefore, when the amount of electrolyte in the capacitor element decreases due to the evaporation of the electrolyte, the conductive polymer becomes more susceptible to oxidative degradation.
  • the initial weight of the electrolyte is large, even if the electrolyte evaporates, sufficient electrolyte will remain to protect the periphery of the conductive polymer. Furthermore, if the sealing body is thick, the electrolyte will be less likely to evaporate, and sufficient electrolyte will remain to protect the periphery of the conductive polymer. Furthermore, if the sealing body has a small sealing surface area, the electrolyte will be less likely to evaporate, and sufficient electrolyte will remain to protect the periphery of the conductive polymer.
  • the electrolyte loading coefficient R is 3.93 mg mm/mm2 or more , oxidative degradation of the conductive polymer due to evaporation of the electrolyte is suppressed, and the tan ⁇ of the electrolytic capacitor is suppressed.
  • the electrolyte loading coefficient R is 8.5 mg ⁇ mm/mm 2 or less, swelling of the solid electrolytic capacitor in a reflow process environment or a high-temperature environment can be suppressed.
  • This electrolyte is a solution in which an anionic component and a cationic component are added to a solvent.
  • the anionic component and cationic component are typically salts of organic acids, salts of inorganic acids, or salts of complex compounds of organic acids and inorganic acids, and are added to the solvent as ion-dissociable salts that dissociate into the anionic component and the cationic component.
  • An acid that becomes the anionic component and a base that becomes the cationic component may also be added separately to the solvent.
  • the electrolyte does not necessarily require that the solvent contain either the anionic component or the cationic component, or both the anionic and cationic components.
  • Organic acids that can serve as anionic components include carboxylic acids such as oxalic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, adipic acid, benzoic acid, toluic acid, enanthic acid, malonic acid, 1,6-decanedicarboxylic acid, 1,7-octanedicarboxylic acid, azelaic acid, resorcylic acid, phloroglucinic acid, gallic acid, gentisic acid, protocatechuic acid, pyrocatechuic acid, trimellitic acid, pyromellitic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, t-butyladipic acid, and 11-vinyl-8-octadecenedioic acid, as well as phenols and
  • Inorganic acids include boric acid, phosphoric acid, phosphorous acid, hypophosphorous acid, carbonic acid, and silicic acid.
  • Examples of composite compounds of organic and inorganic acids include borodisalicylic acid, borodioxalic acid, borodiglycolic acid, borodimalonic acid, borodisuccinic acid, borodiadipic acid, borodiazelaic acid, borodibenzoic acid, borodimaleic acid, borodilactic acid, borodimalic acid, boroditartaric acid, borodicitric acid, borodiphthalic acid, borodi(2-hydroxy)isobutyric acid, borodiresorcylic acid, borodimethylsalicylic acid, borodinaphthoic acid, borodimandelic acid, and borodi(3-hydroxy)propionic acid.
  • Cation components include ammonium, quaternary ammonium, quaternized amidinium, amine, sodium, potassium, etc.
  • Quaternary ammonium includes tetramethylammonium, triethylmethylammonium, tetraethylammonium, etc.
  • Quaternary amidinium includes ethyldimethylimidazolinium, tetramethylimidazolinium, etc.
  • Amines include primary amines, secondary amines, and tertiary amines.
  • Primary amines include methylamine, ethylamine, propylamine, etc.; secondary amines include dimethylamine, diethylamine, ethylmethylamine, dibutylamine, etc.; and tertiary amines include trimethylamine, triethylamine, tributylamine, ethyldimethylamine, ethyldiisopropylamine, etc.
  • additives can be added to the electrolyte.
  • additives include complex compounds of boric acid and polysaccharides (mannitol, sorbitol, etc.), complex compounds of boric acid and polyhydric alcohols, borate esters, nitro compounds, phosphate esters, and colloidal silica. These may be used alone or in combination of two or more.
  • Nitro compounds suppress the generation of hydrogen gas within the electrolytic capacitor. Examples of nitro compounds include o-nitrobenzoic acid, m-nitrobenzoic acid, p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol, and p-nitrophenol.
  • the anions and cations may be added to the electrolyte in the form of ionically dissociable salts, or the anions (acids) and cations (bases) may be added to the electrolyte separately as solute components.
  • the anions and cations may be used alone or in combination of two or more.
  • the electrolyte may also be composed solely of glycerins, without containing additives or ionically dissociable salts that dissociate into anions and cations.
  • solid electrolyte examples include manganese dioxide or 7,7,8,8-tetracyanoquinodimethane (TCNQ) complexes, as well as conductive polymers.
  • Conductive polymers are self-doped conjugated polymers doped with an intramolecular dopant, or conjugated polymers doped with external dopant molecules.
  • Conjugated polymers are obtained by chemical oxidative polymerization or electrolytic oxidative polymerization of monomers or their derivatives having ⁇ -conjugated double bonds.
  • the dopant or external dopant molecule acts as an acceptor that readily accepts electrons into the conjugated polymer, or as a donor that readily donates electrons, which allows the conductive polymer to exhibit high conductivity.
  • conjugated polymers any known polymer can be used without particular limitation. Examples include polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, and polythiophene vinylene. These conjugated polymers may be used alone, in combination with two or more types, or as copolymers of two or more types of monomers.
  • conjugated polymers formed by polymerizing thiophene or its derivatives are preferred, and conjugated polymers formed by polymerizing 3,4-ethylenedioxythiophene (i.e., 2,3-dihydrothieno[3,4-b][1,4]dioxin), 3-alkylthiophene, 3-alkoxythiophene, 3-alkyl-4-alkoxythiophene, 3,4-alkylthiophene, 3,4-alkoxythiophene, or derivatives thereof are preferred.
  • 3,4-ethylenedioxythiophene i.e., 2,3-dihydrothieno[3,4-b][1,4]dioxin
  • 3-alkylthiophene 3-alkoxythiophene
  • 3-alkyl-4-alkoxythiophene 3-alkyl-4-alkoxythiophene
  • 3,4-alkylthiophene, 3,4-alkoxythiophene, or derivatives thereof are preferred.
  • a polymer of 3,4-ethylenedioxythiophene known as EDOT, i.e., poly(3,4-ethylenedioxythiophene), known as PEDOT
  • EDOT 3,4-ethylenedioxythiophene
  • PEDOT poly(3,4-ethylenedioxythiophene)
  • a substituent may be added to 3,4-ethylenedioxythiophene.
  • alkylated ethylenedioxythiophene in which an alkyl group having 1 to 5 carbon atoms is added as a substituent, may be used.
  • alkylated ethylenedioxythiophene examples include methylated ethylenedioxythiophene (i.e., 2-methyl-2,3-dihydro-thieno[3,4-b][1,4]dioxin), ethylated ethylenedioxythiophene (i.e., 2-ethyl-2,3-dihydro-thieno[3,4-b][1,4]dioxin), and butylated ethylenedioxythiophene (i.e., 2-butyl-2,3-dihydro-thieno[3,4-b][1,4]dioxin).
  • methylated ethylenedioxythiophene i.e., 2-methyl-2,3-dihydro-thieno[3,4-b][1,4]dioxin
  • ethylated ethylenedioxythiophene i.e., 2-ethyl-2,3-dihydro-thieno
  • dopant can be used without any particular limitation.
  • a single dopant may be used, or two or more may be used in combination.
  • a polymer or a monomer may also be used.
  • dopants include inorganic acids such as polyanions, boric acid, nitric acid, and phosphoric acid, and organic acids such as acetic acid, oxalic acid, citric acid, tartaric acid, squaric acid, rhodizonic acid, croconic acid, salicylic acid, p-toluenesulfonic acid, 1,2-dihydroxy-3,5-benzenedisulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, borodisalicylic acid, bisoxalateborate acid, sulfonylimide acid, dodecylbenzenesulfonic acid, propylnaphthalenesulfonic acid, and butylnaphthalenesulfonic acid
  • polyanions include substituted or unsubstituted polyalkylenes, substituted or unsubstituted polyalkenylenes, substituted or unsubstituted polyimides, substituted or unsubstituted polyamides, and substituted or unsubstituted polyesters, including polymers consisting only of structural units having anionic groups, and polymers consisting of structural units having anionic groups and structural units not having anionic groups.
  • polyanions include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallylsulfonic acid, polyacrylic sulfonic acid, polymethacrylic sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprenesulfonic acid, polyacrylic acid, polymethacrylic acid, and polymaleic acid.
  • the anode body and the cathode body are foil bodies based on a valve metal.
  • the foil body may be formed by stretching the valve metal or by sintering a valve metal powder.
  • the anode body In wound electrolytic capacitors, the anode body has a long strip shape, while in laminated and flat electrolytic capacitors, the anode body is a flat plate.
  • Valve metals include aluminum, tantalum, niobium, niobium oxide, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony.
  • the purity of the anode body is preferably 99.9% or higher, and that of the cathode body is preferably about 99% or higher, but impurities such as silicon, iron, copper, magnesium, and zinc may be contained.
  • a surface-expanding layer is formed on one or both sides of the anode foil.
  • a surface-expanding layer may also be formed on one or both sides of the cathode foil.
  • the surface-expanding layer is an etching layer formed by etching the foil, a sintered layer formed by sintering valve metal powder, or a vapor-deposited layer formed by vapor-depositing valve metal particles onto the foil.
  • the surface-expanding layer has a porous structure, consisting of tunnel-shaped pits, spongy pits, or gaps between densely packed powder or particles. Tunnel-shaped etching pits are holes dug in the thickness direction of the foil. Furthermore, spongy etching pits make the surface-expanding layer into a sponge-like layer with a series of fine, open gaps.
  • a dielectric film is formed on one or both sides of the anode body on which the surface expansion layer is formed. If a surface expansion layer is formed, it is formed on the surface of the surface expansion layer, following the irregularities of the surface expansion layer.
  • the dielectric film is typically an oxide film formed on the surface of the anode body; if the anode body is made of aluminum, it is an aluminum oxide layer formed by oxidizing the surface of the surface expansion layer. This dielectric film is formed by chemical conversion treatment in which a voltage is applied in an aqueous solution of adipic acid, boric acid, phosphoric acid, or the like.
  • a chemical repair process may be carried out to repair the bare valve metal portions exposed when the anode and cathode bodies are cut to the desired width, as well as defects in the anode and cathode bodies caused by physical stress during winding, etc.
  • Examples 1 to 8 in which glycerin is 40 wt% or more relative to the total solvent of the electrolyte solution, have a ⁇ Cap of -16% or more.
  • Examples 1 to 8 in which glycerin is 40 wt% or more relative to the total solvent of the electrolyte solution, have a ⁇ Cap of -16% or more.
  • those in which glycerin is 40 wt% or more relative to the total solvent of the electrolyte solution maintain their capacitance well even when exposed to high temperatures for long periods of time.
  • the sealant consists of only an elastomer.
  • the elastomer in Examples 11 to 17 consists of 32 wt% elastomer, 16 wt% carbon, 42 wt% inorganic filler, vulcanizing agent, stearic acid, zinc oxide, and silane coupling agent.
  • the entire elastomer is regular butyl.
  • the vulcanizing agent, stearic acid, zinc oxide, and silane coupling agent were added so that the total amount was 10 wt%.
  • electrolyte types A to C Three types of electrolytes were prepared: electrolyte types A to C.
  • the solvent for electrolyte type A was composed of 40 wt% glycerin and 60 wt% ethylene glycol.
  • the solvent for electrolyte type B was composed of 60 wt% glycerin and 40 wt% ethylene glycol, and the solvent for electrolyte type C was composed of 80 wt% glycerin and 20 wt% ethylene glycol.
  • the electrolyte for electrolyte types A to C was ammonium azelaate, which was added at a ratio of 0.16 mol per 1 kg of electrolyte.
  • Electrolytic capacitors combining the elastic bodies of Examples 11 to 17 with electrolyte type A are referred to as Examples 11A to 17A.
  • Electrolytic capacitors combining the elastic bodies of Examples 11 to 17 with electrolyte type B are referred to as Examples 11B to 17B.
  • Electrolytic capacitors combining the elastic bodies of Examples 11 to 17 with electrolyte type C are referred to as Examples 11C to 17C. These electrolytic capacitors were manufactured using the same manufacturing method and conditions as Example 1, except for the elastic body and electrolyte, and have the same configuration as Example 1.
  • the electrolytic capacitors were also exposed to a high-temperature environment at 170°C.
  • the capacitance (Cap) of each electrolytic capacitor was measured immediately before exposure to the high-temperature environment and after 1,400 hours of exposure to the high-temperature environment, and ⁇ Cap (%), which is the rate of change in capacitance before and after exposure to the high-temperature environment, was calculated.
  • the capacitance measurement method was the same as in Example 3.
  • the leakage current ( ⁇ A) of each electrolytic capacitor was measured after 1,400 hours of exposure to a high-temperature environment.
  • the leakage current was measured on an oscilloscope 120 seconds after applying 35 V in a 20°C temperature environment.
  • the capacitance change rate ⁇ Cap and leakage current of the electrolytic capacitors of Examples 11A to 17A are shown in Table 4 below.
  • the capacitance change rate ⁇ Cap and leakage current of the electrolytic capacitors of Examples 11B to 17B are shown in Table 5 below.
  • the capacitance change rate ⁇ Cap and leakage current of the electrolytic capacitors of Examples 11C to 17C are shown in Table 6 below.
  • the electrolytic capacitors of Examples 11A to 17A all have excellent ⁇ Cap. Furthermore, the electrolytic capacitors of Examples 11A to 14A are superior to those of Examples 15A to 17A in that they have low leakage current, at a maximum of about 1/95th.
  • the electrolytic capacitors of Examples 11B to 17B all have excellent ⁇ Cap. Furthermore, the electrolytic capacitors of Examples 11B to 14B are superior to Examples 15B to 17B in that they have low leakage current, at a maximum of approximately 1/126th.
  • the electrolytic capacitors of Examples 11C to 17C all have excellent ⁇ Cap. Furthermore, the electrolytic capacitors of Examples 11C to 14C are superior to Examples 15C to 17C in that they have low leakage current, at most 1/200th of that of Examples 15C to 17C.
  • Electrolytic capacitors of Examples 18A to 22A and Examples 18B to 22B were fabricated.
  • the electrolytic capacitors of Examples 18A to 22A had the same configuration as Example 1, except that the amount of electrolyte was different from that of Example 1, and the amount of glycerin in the electrolyte was 40 wt % relative to the total amount of solvent.
  • the electrolytic capacitors of Examples 18B to 22B had the same configuration as Example 3, except that the amount of electrolyte was different from that of Example 3, and the amount of glycerin in the electrolyte was 60 wt % relative to the total amount of solvent.
  • the sealing bodies used in the electrolytic capacitors of Examples 18A to 22A and Examples 18B to 22B were cylindrical, with a radius of 4.72 mm and a height of 2.5 mm.
  • the electrolyte loading coefficient R of each electrolytic capacitor was adjusted as follows:
  • the electrolyte load coefficient R for Examples 18A and 18B was 5.00 mg mm/ mm2 .
  • the electrolyte load coefficient R for Examples 19A and 19B was 4.29 mg mm/ mm2 .
  • the electrolyte load coefficient R for Examples 20A and 20B was 3.93 mg mm/ mm2 .
  • the electrolyte load coefficient R for Examples 21A and 21B was 3.57 mg mm/ mm2 .
  • the electrolyte load coefficient R for Examples 22A and 22B was 3.21 mg mm/ mm2 .
  • the electrolytic capacitors were also exposed to a high-temperature environment at 170°C.
  • the capacitance (Cap) of each electrolytic capacitor was measured immediately before exposure to the high-temperature environment and after 1,400 hours of exposure to the high-temperature environment, and ⁇ Cap (%), which is the rate of change in capacitance before and after exposure to the high-temperature environment, was calculated.
  • the capacitance measurement method was the same as in Example 3.
  • the capacitance change rates ⁇ Cap and tan ⁇ of the electrolytic capacitors of Examples 18A to 22A are shown in Table 7 below.
  • the capacitance change rates ⁇ Cap and tan ⁇ of the electrolytic capacitors of Examples 18B to 22B are shown in Table 8 below.
  • the results of Tables 7 and 8 below are shown in the graph in Figure 2.
  • the horizontal axis is the electrolyte load coefficient R and the vertical axis is tan ⁇ , with the circle plots representing the series of Examples 18A to 22A and the triangle plots representing the series of Examples 18B to 22B.
  • the electrolytic capacitors of Examples 18A to 22A all have excellent ⁇ Cap. Furthermore, the electrolytic capacitors of Examples 18A to 20A have significantly lower tan ⁇ than Examples 21A and 22A. As shown in Table 8 and Figure 2, the electrolytic capacitors of Examples 18B to 22B all have excellent ⁇ Cap. Furthermore, the electrolytic capacitors of Examples 18B to 20B have significantly lower tan ⁇ than Examples 21B and 22B.
  • the dimensions of the electrolyte and the sealing body were adjusted so that the electrolyte loading coefficient R was 3.93 mg mm/mm2 or more .
  • the electrolytic capacitors not only suppressed the decrease in capacitance in high-temperature environments, but also suppressed tan ⁇ .
  • the elastic body of the sealing body contain 31 wt % or more of butyl rubber, making the electrolyte contain 40 wt % or more of glycerin, diglycerin, or both in a solvent, making the elastic body contain 50 wt % or more and 60 wt % or less of carbon and inorganic filler, and making the electrolyte loading coefficient R 3.93 mg mm/mm2 or more , not only is it possible to suppress changes in capacitance but also to lower the tan ⁇ of the electrolytic capacitor.

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Abstract

L'invention concerne : un condensateur électrolytique dans lequel une diminution de la capacité électrostatique est supprimée même dans un environnement à haute température ; et un procédé de fabrication. Le condensateur électrolytique comprend : un élément de condensateur comportant une feuille d'électrode positive, une feuille d'électrode négative, une solution électrolytique et une couche d'électrolyte solide ; un boîtier qui loge l'élément de condensateur ; et un corps d'étanchéité pour sceller le boîtier. Le corps d'étanchéité comporte un corps élastique contenant un élastomère. L'élastomère contient du caoutchouc butyle, et est contenu dans le corps élastique en une quantité de 31% en poids ou plus. La solution électrolytique contient de la glycérine en une quantité de 40% en poids ou plus dans le solvant de la solution électrolytique.
PCT/JP2025/008827 2024-03-11 2025-03-10 Condensateur électrolytique et procédé de fabrication Pending WO2025192529A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20250385050A1 (en) * 2024-06-17 2025-12-18 Tdk Electronics Ag Capacitor and method of forming a capacitor

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07307254A (ja) * 1994-05-16 1995-11-21 Japan Synthetic Rubber Co Ltd 電解コンデンサー用パッキンゴム形成組成物
WO2023176392A1 (fr) * 2022-03-17 2023-09-21 日本ケミコン株式会社 Condensateur électrolytique

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07307254A (ja) * 1994-05-16 1995-11-21 Japan Synthetic Rubber Co Ltd 電解コンデンサー用パッキンゴム形成組成物
WO2023176392A1 (fr) * 2022-03-17 2023-09-21 日本ケミコン株式会社 Condensateur électrolytique

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20250385050A1 (en) * 2024-06-17 2025-12-18 Tdk Electronics Ag Capacitor and method of forming a capacitor

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