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
  • H01G9/004—Details
  • H01G9/022—Electrolytes; Absorbents
• • 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
  • H01G9/022—Electrolytes; Absorbents
  • H01G9/035—Liquid electrolytes, e.g. impregnating materials
• • 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
• • 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
  • H01G9/15—Solid electrolytic capacitors

Definitions

• the present invention relates to an electrolytic solution for an electrolytic capacitor that can suppress expansion of an outer container even when exposed to a high temperature atmosphere in a solder reflow process or the like, and an electrolytic capacitor using this electrolytic solution.
• Patent Documents 1 and 2 disclose a solid electrolytic capacitor using a solid electrolyte made of a conductive polymer such as polypyrrole, polythiophene, or polyaniline.
• a composite compound of an organic acid such as phthalic acid, maleic acid, adipic acid, and salicylic acid and an inorganic acid such as boric acid, phosphoric acid, and bohic acid, typically borodisalicylic acid and boro.
• Electrolyte solutions containing ammonium salts or amine salts such as diglycolic acid and borodishuic acid as solutes and various organic solvents such as ⁇ -butyrolactone, ⁇ -valerolactone and ethylene glycol as solvents are used. Since such a solid electrolytic capacitor has a large capacity and a small leakage current, it is attracting attention as an electrolytic capacitor having high characteristics.
• Patent Document 3 an amine salt of a boron complex of a dicarboxylic acid or a hydroxycarboxylic acid is used as an electrolyte, an aprotic organic solvent such as ⁇ -butyrolactone is used, and an aromatic carboxylic acid having a sulfonic acid group or a salt thereof and ethylene glycol are used.
• An electrolytic capacitor using an electrolytic solution containing a protonic organic solvent such as, etc. as an additive is disclosed.
• these electrolytic capacitors are required to have heat resistance when using an electronic device incorporating the electrolytic capacitor, and further heat resistance when mounting the electrolytic capacitor on a substrate.
• a solder reflow process is used for surface mounting of electrolytic capacitors.
• lead-free soldering is particularly required for environmental protection, and the solder reflow process has high heat resistance of 250 ° C. or higher. It is becoming necessary.
• the pressure inside the outer container rises due to the generation of gas from the electrolytic solution in the electrolytic capacitor, causing the outer container to expand, for example, the phenomenon that the height dimension value of the electrolytic capacitor increases. Be looked at.
• the electrolytic capacitor mounted on the board may be hindered from being mounted on the device, and the characteristics of the electrolytic capacitor itself may be deteriorated, which may impair its reliability (see Patent Documents 4 and 5). ).
• An object of the present invention is to provide an electrolytic solution for an electrolytic capacitor using an acidic organic solvent as an electrolytic solution and an electrolytic capacitor using this electrolytic solution.
• an organic carboxylic acid having a hydroxy group and a boron compound are contained as solutes in a protonic organic solvent such as a polyhydric alcohol, with respect to 1 mol of the organic carboxylic acid having such a hydroxy group.
• a protonic organic solvent such as a polyhydric alcohol
• An electrolytic solution for an electrolytic capacitor having an anode foil having a dielectric oxide film layer on its surface, a cathode foil, and a capacitor element having a solid electrolyte layer, and an electrolytic solution impregnated in the capacitor element in an outer container.
• the electrolytic solution contains an organic carboxylic acid having a hydroxy group, a boron compound and a solvent, and the content of the boron compound is 0.6 mol or more with respect to 1 mol of the organic carboxylic acid having a hydroxy group.
• An electrolytic solution for an electrolytic capacitor characterized in that the solvent contains a protonic organic solvent and an increase in pressure inside the outer container can be suppressed when the electrolytic capacitor is exposed to a high temperature of 250 ° C. or higher.
• the present invention even when an electrolytic capacitor using a protonic organic solvent such as polyhydric alcohol as an electrolytic solution is exposed to a high temperature of 250 ° C. or higher, further 260 ° C. or higher in a solder reflow process or the like, the inside of the outer container An electrolytic solution for an electrolytic capacitor capable of suppressing an increase in the pressure of the outer container and suppressing expansion of the outer container, and an electrolytic capacitor using this electrolytic solution can be obtained. Further, the electrolytic capacitor using the electrolytic solution of the present invention suppresses dimensional changes and characteristic changes due to expansion of the outer container even in a solder reflow process at a high temperature of 250 ° C. or higher, and also in a high temperature usage environment. It has high reliability with little change in characteristics.
• a protonic organic solvent such as polyhydric alcohol as an electrolytic solution
• the mechanism by which the increase in pressure in the outer container can be suppressed and the heat resistance can be improved is considered as follows. It has a hydroxy group by setting the content of the boron compound to 1 mol of the organic carboxylic acid having a hydroxy group contained in the electrolytic solution using a protonic organic solvent as a solvent to 0.6 mol or more, and further to more than 0.6 mol. It is possible to suppress the generation of carbon dioxide and the like due to the decomposition of organic carboxylic acids, composite compounds with the boron compounds, or salts thereof. It is considered that the suppression of the generation of carbon dioxide and the like due to this decomposition can be surely prevented as the content of the boron compound per 1 mol of the organic carboxylic acid increases to 0.7 mol or more and further to 0.9 mol or more.
• the electrolytic solution of the present invention is used for a solid electrolytic capacitor having an anode and a cathode having a dielectric oxide film layer on the surface, a capacitor element having a solid electrolyte, and an electrolytic solution impregnated in the capacitor element.
• Solid electrolytic capacitors are obtained by known methods.
• the solid electrolyte used in the present invention is a conductive polymer doped with a dopant component.
• the conductive polymer polypyrrole, polythiophene, polyaniline or derivatives thereof are used.
• the solid electrolyte layer used in the present invention can be obtained by chemically oxidatively polymerizing or electrolytically oxidatively polymerizing a monomer of a conductive polymer in the presence of the above-mentioned dopant component. Alternatively, it can be obtained by contacting a dispersion liquid or a dissolved solution in which a conductive polymer formed into fine particles by chemical oxidation polymerization is dispersed in a solvent such as water. Further, in the chemical oxidation polymerization or electrolytic oxidation polymerization, a part or all of the monomer of the dopant component and the conductive polymer may be replaced with a monomer having a functional group capable of chemical oxidation doping.
• the monomer of the conductive polymer is 3,4-ethylenedioxythiophene, methyl-3,4-ethylenedioxythiophene, ethyl-3,4-ethylenedioxythiophene, propyl-3,4-ethylene.
• 3,4-ethylenedioxythiophene, methyl-3,4-ethylenedioxythiophene, or ethyl-3,4-ethylenedioxythiophene which is excellent in that the ESR of the electrolytic capacitor is low, is particularly preferable.
• the dopant component may have a functional group capable of chemically oxidizing a polymer, and a sulfate ester group, a phosphoric acid ester group, a phosphoric acid group, a carboxyl group, a sulfo group and the like are preferable. Among these, a sulfate group, a carboxyl group, and a sulfo group are more preferable, and a sulfo group is particularly preferable, from the viewpoint of the doping effect.
• An example of a monomer having a functional group in which the above chemical oxidation doping can occur is 6- (2,3-dihydro-thieno [3,4-b] [1,4] dioxin-2-yl) hexane-1-sulfon.
• Water or an organic solvent can be used as the dispersion medium.
• organic solvent alcohols, ketones, esters, ethers, cellosolves, aromatic hydrocarbons, aliphatic hydrocarbons and the like can be used.
• the conductive polymer dispersion liquid or solution of the present invention may contain a high boiling point organic solvent.
• a high boiling point organic solvent having a boiling point of 150 ° C. or higher is particularly preferable.
• Specific examples of the high boiling point organic solvent include N-methyl-2-pyrrolidone, dimethyl sulfoxide, ⁇ -butyrolactone, sulfolane, dimethyl sulfone, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol and the like.
• ethylene glycol or ⁇ -butyrolactone is more preferable because it can form a solid electrolyte layer containing a conductive polymer having a uniform surface.
• the content of the organic solvent in the conductive polymer dispersion or solution is preferably 1 to 20% by mass, particularly preferably 5 to 15% by mass.
• the content of the organic solvent is less than 1% by mass, the effect of forming a solid electrolyte layer containing a conductive polymer having a uniform surface is slightly inferior, and when it exceeds 20% by mass, there is a problem that the drying step takes time. ..
• the conductive polymer dispersion liquid or solution may contain a binder resin, a surfactant, and an alkaline compound in order to adjust the film-forming property and the film strength.
• the conductive polymer dispersion liquid is one in which the conductive polymer is dispersed in a dispersion medium, and a part of the conductive polymer may be dissolved in the dispersion medium.
• a valve acting metal is preferable, and specifically, one selected from the group consisting of aluminum, tantalum, niobium and titanium can be mentioned, and among them, aluminum is preferable.
• the valvening metal is usually used in the form of a sintered body or foil.
• the electrolytic capacitor can be a chip type or a wound type depending on the shapes of the anode and the cathode used.
• the solid electrolyte may be formed by contacting the capacitor element with a dispersion liquid or solution of a conductive polymer by means such as immersion and drying the solvent, or by forming the capacitor element conductive. It may be formed by immersing it in a monomer solution of a sex polymer and then by chemical polymerization or electrolytic polymerization.
• the electrolytic solution in the present invention contains an electrolyte and an organic solvent, and the electrolyte contains an organic carboxylic acid having a hydroxy group and a boron compound.
• the organic carboxylic acid having a hydroxy group preferably has a ring structure of 1 to 4, more preferably 1 or 2, particularly preferably one, and the hydroxy group is preferably 1 to 4, more preferably 1 or more. 2. Particularly preferably, one having one is preferable.
• organic carboxylic acid having a hydroxy group examples include glycolic acid, lactic acid, 3-hydroxypropionic acid, mandelic acid, salicylic acid, 3-methylsalicylic acid, 4-methylsalicylic acid, 5-methylsalicylic acid, 6-methylsalicylic acid, and the like.
• 3-Nitrosalicylic acid 4-nitrosalicylic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, 3-sulfosalicylic acid, 4-sulfosalicylic acid, 5-sulfosalicylic acid, 4-hydroxysalicylic acid, 5-hydroxysalicylic acid, 3-methoxy Salicylic acid, 4-methoxysalicylic acid, 5-methoxysalicylic acid, methylene disalicylic acid, 1-hydroxy-2-naphthoic acid, 2-hydroxy-1-naphthoic acid, 3-hydroxy-2-naphthoic acid, 3-hydroxy-7-methyl Examples thereof include -2-naphthoic acid and 4,4'-methylenebis (3-hydroxy-2-naphthoic acid).
• aromatic carboxylic acid is preferable, and salicylic acid is particularly preferable.
• Examples of the boron compound contained in the electrolytic solution in the present invention include boric acid or borate esters (trimethyl borate, triethyl borate, tripropyl borate, tributyl borate, triphenyl borate, etc.).
• boric acid having excellent properties is preferable.
• the ratio of the boron compound to the organic carboxylic acid having a hydroxy group is important, and the boron compound is contained in an amount of 0.6 mol or more with respect to 1 mol of the organic carboxylic acid having a hydroxy group. It is preferably contained in an amount of 0.65 mol or more, more preferably 0.7 mol or more, still more preferably 0.9 mol or more.
• the content ratio of the boron compound is contained in the above range, a sufficient effect of suppressing the expansion of the outer container can be obtained when exposed to a high temperature of 250 ° C. or higher.
• the content ratio of the boron compound when the content ratio of the boron compound is large, the ESR characteristics of the capacitor are deteriorated under high temperature conditions such as 100 ° C. or higher, so that the content ratio of the boron compound is 1 mol of the organic carboxylic acid having a hydroxy group. On the other hand, it is preferably 5 mol or less, more preferably 3.5 mol or less, still more preferably 2.0 mol or less, and particularly preferably 1.5 mol or less.
• the boron compound contained in the electrolytic solution in the present invention may be present separately from the organic carboxylic acid having a hydroxy group in the electrolytic solution, and a part or all of both may have a hydroxy group. It may exist as a composite compound of the organic carboxylic acid having and a boron compound.
• the electrolytic solution in the present invention preferably contains ammonia, a 1st to 4th grade amine, or an amidine compound in addition to the organic carboxylic acid having a hydroxy group and the boron compound.
• tertiary amines are preferable.
• tertiary amines include trialkylamines (trimethylamine, dimethylethylamine, methyldiethylamine, triethylamine, dimethyln-propylamine, dimethylisopropylamine, methylethyln-propylamine, methylethylisopropylamine, diethyln-propylamine, diethyl.
• Examples thereof include isopropylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, tritert-butylamine and the like, and phenyl group-containing amines (dimethylphenylamine, methylethylphenylamine, diethylphenylamine and the like).
• trialkylamine is preferable, and more preferably, one or more selected from the group consisting of trimethylamine, dimethylethylamine, methyldiethylamine and triethylamine is contained.
• the electrolytic solution of the present invention contains ammonia, a 1st to 4th grade amine, or an amidine compound, a part or all of them is between an organic carboxylic acid having a hydroxy group and / or a boron compound or a composite compound. Although its structure is not always clear, it seems that some kind of complex compound is formed.
• the organic solvent used in the electrolytic solution of the present invention is a protonic organic solvent, and the solvent may be used alone or in combination of two or more.
• it is necessary to use a protic and aprotic organic solvent and when an aprotic organic solvent such as ⁇ -butyrolactone is used as the solvent, the exterior is used during reflow soldering even if the amount of the boron compound of the present invention is not added. Since the expansion of the container is small, it does not meet the object of the present invention.
• the electrolytic solution of the present invention is characterized in that the content ratio of the boron compound to 1 mol of the organic carboxylic acid having a hydroxy group is 0.6 mol or more, and is characterized by containing ⁇ -butyrolactone which is an aprotic organic solvent and the like.
• ⁇ -butyrolactone which is an aprotic organic solvent and the like.
• the protonic organic solvent in the electrolytic solution of the present invention is preferably 65% by mass or more, more preferably 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 85% by mass or more.
• Protonic organic solvents include monohydric alcohols (methanol, ethanol, propanol, butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.), polyhydric alcohols and alkoxy alcohol compounds (ethylene glycol, propylene glycol, diethylene glycol). , Triethylene glycol, glycerin, methyl cellosolve, ethyl cellosolve, methoxypropylene glycol, dimethoxypropanol, etc.), polyalkylene glycols (polyethylene glycol, polypropylene glycol, etc.) and the like. Among them, those having a boiling point of 150 ° C.
• examples thereof include monohydric alcohols (hexanol, cyclohexanol, benzyl alcohol, etc.), polyhydric alcohols, and alkoxyalcohol compounds (ethylene).
• examples thereof include glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerin, methyl cellosolve, ethyl cellosolve, methoxypropylene glycol, dimethoxypropanol, etc., and polyalkylene glycols (polyethylene glycol, polypropylene glycol, etc.).
• the organic solvent used in the electrolytic solution is preferably at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, benzyl alcohol and glycerin because of the high capacity development of the capacitor.
• ethylene glycol, diethylene glycol, or polyethylene glycol is preferable.
• the electrolytic solution of the present invention may contain an aprotic solvent.
• an aprotic solvent such as ⁇ -butyrolactone
• the organic carboxylic acid having a hydroxy group which is the solute of the electrolytic solution of the present invention, and /
• the solubility of the boron compound in ⁇ -butyrolactone is small, and the contribution is small in that the expansion of the outer container is prevented during reflow soldering. Therefore, even if the aprotic solvent in the electrolytic solution of the present invention is contained, it is preferably 80% by mass or less, preferably 40% by mass or less, and more preferably 20% by mass or less in the total solvent. Particularly preferably, it is 10% by mass or less.
• aprotonic solvent examples include ⁇ -butylolactone, ⁇ -valerolactone, and amides (N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-Dimethylacetamide, N-ethylacetamide, N, N-diethylacetamide, hexamethylphosphoricamide, etc.), sulforane system (sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, etc.), chain sulfone system (dimethyl) Symphonic acid, ethylmethylsulfone, ethylisopropylsulfone), cyclic amides (N-methyl-2-pyrrolidone, etc.), carbonates (ethylene carbonate, propylene carbonate, isobutylene carbonate, etc.), nitriles (nitrile,
• the content of the organic carboxylic acid having a hydroxy group in the electrolytic solution of the present invention is preferably 0.1 to 40% by mass, more preferably 1 to 20% by mass, and particularly preferably 3 to 10% by mass. If the content is less than 0.1% by mass, it is difficult to obtain sufficient electrical characteristics, while if it exceeds 40% by mass, the maintenance rate of low ESR decreases in a high temperature environment.
• the content of the boron compound is 0.6 mol or more, preferably 0.65 mol or more, and a ratio of 0.7 to 2.0 mol with respect to 1 mol of the organic carboxylic acid having a hydroxy group. Is more preferable, and 0.9 to 1.5 mol is particularly preferable. When the content is less than 0.6 mol with respect to 1 mol of the organic carboxylic acid, it is difficult to obtain a sufficient effect of suppressing swelling during reflow.
• the electrolytic solution of the present invention contains the above-mentioned organic carboxylic acid having a hydroxy group, a boron compound, preferably ammonia, or 1st to 4th grade amines, respectively, with respect to the above-mentioned organic solvent.
• Manufactured by addition to, simultaneously or temporally. When these are added, it can be carried out with stirring as needed and with heating as needed. These stirring and heating can be performed under appropriate conditions, and for example, heating can be performed at 35 to 120 ° C.
• the electrolytic solution of the present invention may have a hydroxy group in advance by reacting an organic carboxylic acid having a hydroxy group with a boron compound in advance and adding the reaction product to the above-mentioned organic solvent. It can also be produced by reacting an organic carboxylic acid with a boron compound and ammonia or a 1st to 4th grade amine, and adding the reaction product to the above-mentioned organic solvent.
• the electrolytic solution of the present invention when the amount of water contained therein is preferably 1% by mass or less, the increase in internal pressure is suppressed even when heat of 250 ° C. or higher is applied, for example, in the case of a solder reflow step. Excellent characteristics can be obtained in that it can be used.
• the water content is more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less.
• the water content can be adjusted by removing the raw material of the electrolytic solution such as the organic solvent used and the water content in the prepared electrolytic solution. The water content can be removed, for example, by heating the electrolytic solution, distilling it under reduced pressure, treating it with a dehydrating agent, or a combination thereof.
• the electrolytic solution of the present invention can obtain excellent characteristics in that it can maintain a low ESR when its pH is preferably 2 to 6. The reason is not clear, but the pH is more preferably 2.5 to 5.5, and particularly preferably 3 to 5.
• Substances other than the above can be added to the electrolytic solution of the present invention for the purpose of improving characteristics such as life performance and resistance performance of the electrolytic capacitor.
• additive substances are not particularly limited.
• Phosphorus compounds phosphate ester, etc.
• polysaccharides mannitol, sorbit, etc.
• complex compounds of boric acid and polysaccharides mannitol, sorbit, etc.
• boric acid and polyhydric alcohols ethylene glycol, glycerin, etc.
• nitro compounds o-nitrobenzoic acid, m-nitrobenzoic acid, p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol, p-nitrophenol, p-nitrobenzyl alcohol, etc. Be done.
• an antioxidant can be added to the electrolytic solution, and the antioxidants include phenol compounds (catechol, hydroquinone, pyrogallol, etc.), amine compounds, azo compounds, silane compounds, quinone compounds, carboxylic acid compounds, and the like. Can be mentioned.
• the solid electrolytic capacitor of the present invention is a capacitor element in which a gap portion in the capacitor element is filled with the electrolytic solution of the present invention by immersing the capacitor element on which the solid electrolyte layer is formed in the electrolytic solution of the present invention according to a known method. Is manufactured by inserting the capacitor into an outer container, attaching a sealing material or the like to the opening end, and tightening the capacitor.
• the material of the outer container used for manufacturing the solid electrolytic capacitor of the present invention aluminum, an aluminum alloy, other metals and the like can be widely used.
• the wall thickness of the outer container is preferably 0.2 to 0.7 mm, more preferably 0.2 to 0.4 mm.
• the sealing material of the outer container preferably, butyl rubber, butadiene rubber, styrene-butadiene rubber, EPM, EPDM, or a mixture thereof and the like can be widely used.
• the solid electrolytic capacitor of the present invention thus obtained has excellent heat resistance, and has dimensional changes and characteristics due to expansion of the outer container even in a lead-free solder reflow process at a high temperature of 250 ° C. or higher and further 260 ° C. or higher. Since the change of is suppressed, the dimensional change can be suppressed in the surface mounting process. Further, in recent years, there is little change in characteristics even in a high temperature usage environment such as for in-vehicle use, and it has high reliability. In addition, the solid electrolytic capacitor of the present invention has excellent characteristics such as low ESR characteristics and high capacitance characteristics in a high frequency region, and since it has the above-mentioned high heat resistance, these characteristics may be deteriorated by heat. Absent.
• the amount of polystyrene sulfonic acid contained in the above-mentioned monomer solution was 119 parts by mass with respect to 100 parts by mass of 3,4-ethylenedioxythiophene contained in the monomer solution.
• 0.012 g of iron (III) sulfate as an oxidizing agent and 4.46 g of ammonium persulfate were added dropwise, and the mixture was stirred at room temperature for 15 hours to carry out chemical oxidative polymerization. At this time, the monomer solution changed from pale yellow to dark blue.
• an amphoteric ion exchange resin (trade name of Organo Corporation: MB-1, ion exchange type: ⁇ H, ⁇ OH) was added to the obtained reaction solution, and the mixture was stirred for 2 hours. As a result, the pH of the reaction solution changed from 1.15 to 1.83. Thus, a conductive polymer dispersion containing poly (3,4-ethylenedioxythiophene) doped with 1.3% by mass polystyrene sulfonic acid was prepared.
• a capacitor element After the surface is etched, a chemical conversion treatment is performed to form an oxide film layer, and an aluminum anode foil to which lead terminals are attached and an aluminum cathode foil to which the surface is etched and to which lead terminals are attached are separated by a separator (thickness) made of cellulose fibers.
• a capacitor element was manufactured by winding through (0.05 mm).
• Example 1 The capacitor element obtained above was immersed in the conductive polymer dispersion, the capacitor element was pulled up, and then the solvent was evaporated to form a solid electrolyte layer made of the conductive polymer. Next, the amounts of salicylic acid, boric acid, dimethylethylamine, and ethylene glycol shown in Table 1 were mixed with stirring at 90 to 95 ° C. to produce an electrolytic solution, and the electrolytic solution was impregnated into the capacitor element. .. Next, the capacitor element was inserted into a bottomed cylindrical metal-aluminum case (case material thickness: 0.3 mm), a sealing rubber was attached to the end of the opening, and the capacitor element was sealed by curling.
• a bottomed cylindrical metal-aluminum case case material thickness: 0.3 mm
• an aluminum electrolytic capacitor was prepared.
• the rated voltage of this electrolytic capacitor was 35 V, and the external dimensions of the electrolytic capacitor after sealing were a cylinder having a diameter of 10 mm and a height of 10 mm.
• Example 2 to 10 Comparative Examples 1 to 5
• Examples 2 to 10 and Comparative Example were carried out in the same manner as in Example 1 except that an electrolytic solution obtained by mixing the amounts of each component shown in Table 1 with stirring at 90 to 95 ° C. was used. Electrolytic capacitors 1 to 5 were prepared.
• Comparative Example 6 The amounts of each component shown in Table 1 were mixed and dissolved while stirring at 90 to 95 ° C., but when cooled to 25 ° C., a white solid was precipitated and an electrolytic solution could not be prepared.
• Table 1 shows the water content (mass%) and pH of the electrolytic solution used in each of the electrolytic capacitors of Examples 1 to 10 and Comparative Examples 1 to 5.
• the water content was measured by the Karl Fischer titration method using a trace water measuring device CA-200 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.).
• the pH was measured using a pH meter HM-30R manufactured by DKK-TOA CORPORATION.
• the elongation ⁇ L (mm) of the dimension in the height direction of the cylindrical electrolytic capacitor was obtained by the following formula, and it is shown in Table 1.
• the "height dimension” is the distance between the centers on both bottom surfaces of the cylindrical capacitor, and was measured using a caliper.
• ⁇ L (height dimension after reflow test)-(height dimension before reflow test)
• the electrolytic capacitors of Examples 1 to 10 using the electrolytic solution containing 0.6 mol or more of boric acid with respect to 1 mol of the organic carboxylic acid having a hydroxy group are Comparative Example 1. It can be seen that ⁇ L (mm) is smaller than that of the electrolytic capacitors of to 5 and the expansion of the outer container is suppressed even at a high temperature of 260 ° C.
• the present invention is widely used as an electrolytic solution in an electrolytic capacitor that is frequently used in power supplies for various consumer devices such as AV devices, mobile phones, and notebook computers, in-vehicle electrical devices, and industrial devices.

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• 2020
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