Electrolytic capacitor

Abstract

To provide an electrolytic capacitor having a long life and a low ESR.SOLUTION: An electrolytic capacitor includes a capacitor element in which an anode foil having a dielectric oxide film and a cathode foil face each other with a separator interposed therebetween, a main body case that houses the capacitor element, and a sealing body that seals the main body case. An electrolyte containing a hydrophilic compound and the hydrophilic compound are held between the anode foil and the cathode foil. The hydrophilic compound dissolves the electrolyte as at least a part of a solvent to form an electrolytic solution. The electrolytic solution is contained in 80% by volume or more of voids of the capacitor element. A sealing body deterioration inhibitor that is incompatible with the hydrophilic compound is disposed inside the main body case. The sealing body deterioration inhibitor is disposed in the main body case in a state of being incompatible with the hydrophilic compound in the capacitor element.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an electrolytic capacitor sealed with a sealing body. [Background technology]

[0002] A conventional electrolytic capacitor is disclosed in Patent Document 1. This electrolytic capacitor includes a main body case, a capacitor element, and a sealing body. The main body case is made of metal and has a cylindrical shape with a bottom, one end of the cylindrical peripheral wall is closed, and the other end has an opening.

[0003] The capacitor element is made by winding anode and cathode foils, each coated with a dielectric oxide film, with a separator between them, and then storing them in a main case. An electrolyte containing a sealant deterioration inhibitor is held between the anode and cathode foils. The electrolyte contains, for example, polyethylene glycol-polypropylene glycol copolymer to dissolve the sealant deterioration inhibitor. The opening of the main case storing the capacitor element is sealed with a rubber seal.

[0004] In the capacitor, the sealant deterioration inhibitor permeates the sealant, thereby preventing deterioration of the sealant in high-temperature environments such as an engine compartment, thereby suppressing evaporation of the electrolyte and maintaining stable characteristics of the electrolytic capacitor over the long term. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2020 / 059091 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional electrolytic capacitors described above, the electrolyte solution containing a polymer compound having a polyoxyethylene group or a polyoxypropylene group has a high viscosity. This reduces the permeability of the sealant deterioration inhibitor dissolved in the electrolyte solution into the sealant. As a result, in high-temperature environments exceeding 150°C, cracks may occur in the sealant before the sealant deterioration inhibitor can fully penetrate, causing the electrolyte to evaporate, potentially shortening the life of the electrolytic capacitor.

[0007] Furthermore, if the amount of sealant deterioration inhibitor in the electrolyte is increased to allow it to penetrate the seal faster, a large amount of insulating sealant deterioration inhibitor will be present inside the capacitor element, which reduces the amount of electrolyte inside the capacitor element by the amount of sealant deterioration inhibitor added, making it difficult to reduce the ESR of the electrolytic capacitor.

[0008] An object of the present invention is to provide an electrolytic capacitor with a long life and low ESR. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides an electrolytic capacitor comprising a capacitor element in which an anode foil and a cathode foil having a dielectric oxide film face each other with a separator interposed therebetween, a main case that houses the capacitor element, and a sealing member that seals the main case, wherein an electrolyte containing a hydrophilic compound and the hydrophilic compound are held between the anode foil and the cathode foil, the hydrophilic compound dissolves the electrolyte as at least a part of a solvent to form an electrolytic solution, the electrolytic solution being contained in 80% or more by volume of the voids in the capacitor element, a sealing member deterioration inhibitor that is incompatible with the hydrophilic compound is disposed inside the main case, and the sealing member deterioration inhibitor is disposed within the main case in a state incompatible with the hydrophilic compound in the capacitor element.

[0010] Furthermore, in the electrolytic capacitor of the present invention having the above-described configuration, the sealant deterioration inhibitor is a terpenoid, an unsaturated fatty acid, a polyglycerin ester containing an unsaturated fatty acid group in the molecule, a saturated fatty acid, or a derivative thereof.

[0011] In the electrolytic capacitor of the present invention having the above-mentioned configuration, the hydrophilic compound forms at least a part of the solvent of the electrolytic solution in which the electrolyte is dissolved, and has a boiling point of 180° C. or higher.

[0012] Furthermore, in the electrolytic capacitor of the present invention having the above-described configuration, the electrolyte is a solid electrolyte, the capacitor element is impregnated with a predetermined liquid, and the hydrophilic compound forms at least a part of the liquid and has a boiling point of 180°C or higher.

[0013] Furthermore, in the electrolytic capacitor of the present invention having the above-mentioned configuration, the hydrophilic compound has a boiling point of 205° C. or higher.

[0014] Furthermore, in the electrolytic capacitor of the present invention having the above-described configuration, the hydrophilic compound contains sulfolane, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, or a derivative thereof.

[0015] Furthermore, in the electrolytic capacitor of the present invention having the above-mentioned configuration, the hydrophilic compound contains polyethylene glycol having a molecular weight of 1,000 or more.

[0016] Furthermore, in the electrolytic capacitor of the present invention having the above-described configuration, the electrolyte is a solid electrolyte, and a substance that is solid at room temperature, in which the electrolyte is dissolved in a solvent that is solid at room temperature and melts in an environment higher than room temperature, is placed in the capacitor element, and the hydrophilic compound forms at least a part of the solvent.

[0017] Furthermore, in the electrolytic capacitor of the present invention having the above configuration, the hydrophilic compound is PEG2000, PEG4000, PEG6000, PEG10000, PEG20000, xylitol or sorbitol. [Effects of the Invention]

[0018] According to the present invention, an electrolyte and a hydrophilic compound are held between the anode foil and the cathode foil, and a sealant deterioration inhibitor that is incompatible with the hydrophilic compound is disposed inside the main case. This allows the sealant deterioration inhibitor to quickly penetrate the seal, thereby suppressing sealant deterioration even in high-temperature environments, resulting in an electrolytic capacitor with a long life and low ESR. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a perspective view of an electrolytic capacitor according to a first embodiment of the present invention, viewed from above; [Figure 2] 1 is a perspective view of an electrolytic capacitor according to a first embodiment of the present invention, viewed from below; [Figure 3] FIG. 1 is a front cross-sectional view showing an electrolytic capacitor according to a first embodiment of the present invention. [Figure 4] FIG. 1 is a perspective view showing a capacitor element of an electrolytic capacitor according to a first embodiment of the present invention; [Figure 5] Graph showing the results of evaluation test 3 [Figure 6] FIG. 10 shows the state of the sealing body 4 of Example 3 after evaluation tests 2 and 3. [Figure 7] FIG. 1 is a diagram showing the state of the sealing body 4 of Comparative Example 5 after Evaluation Tests 2 and 3. FIG. 2 is a perspective view showing the capacitor element of the electrolytic capacitor according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] First Embodiment Embodiments of the present invention will be described below with reference to the drawings. Figures 1 and 2 show a perspective view of an electrolytic capacitor 1 according to a first embodiment, viewed from above and below. The electrolytic capacitor 1 is mounted on a seat plate 15 made of synthetic resin. The seat plate 15 has a pair of through holes 15a and 15b.

[0021] Electrolytic capacitor 1 has lead terminals 8 and 9, which are inserted into through holes 15a and 15b of base plate 15 and bent outward. As a result, electrolytic capacitor 1 is placed on a circuit board while the top surface of main body casing 2 is held by an automated machine, and lead terminals 8 and 9 are soldered to lands on the circuit board for mounting.

[0022] 3 shows a front cross-sectional view of electrolytic capacitor 1. Electrolytic capacitor 1 includes a main case 2, a capacitor element 3, and a sealing member 4. Main case 2 is made of a metal such as aluminum and is formed into a cylindrical shape with a circular cross section and a bottom, with one end closed by an end wall 2a and the other end opening 2b. Capacitor element 3 is housed inside main case 2, and opening 2b is sealed by sealing member 4.

[0023] Sealing body 4 is formed into a disk shape by molding an insulating elastic material and has a pair of through holes 4a, 4b. Lead terminals 8, 9 of capacitor element 3 are inserted into through holes 4a, 4b by press-fitting.

[0024] Rubbers such as butyl rubber, isoprene rubber, silicone rubber, fluororubber, ethylene propylene rubber, and ethylene propylene diene rubber can be used for the sealing body 4. Rubber made of a composite material containing any of these may also be used. Butyl rubber is more preferable because it has high environmental resistance, such as heat aging resistance, chemical resistance, and weather resistance, as well as high electrical insulation properties and low gas permeability.

[0025] With sealing body 4 placed in opening 2b of main case 2, main case 2 is subjected to a drawing process that presses the outer peripheral surface. As a result, main case 2 is formed with protrusion 13 that protrudes toward the inner surface. Protrusion 13 compresses the outer peripheral surface of sealing body 4 in the inward direction, bringing it into close contact with the inner peripheral surface of main case 2. Furthermore, compression of sealing body 4 brings the inner surfaces of through holes 4a, 4b into close contact with lead terminals 8, 9. As a result, opening 2b of main case 2 is sealed by sealing body 4, preventing the electrolyte held in capacitor element 3 from leaking out of main case 2.

[0026] The open end of main body case 2 is folded back to form folded portion 14 on the outer surface of sealing body 4 (the surface opposite capacitor element 3). Folded portion 14 and protruding portion 13 prevent sealing body 4 from slipping out of main body case 2.

[0027] 4 shows a perspective view of capacitor element 3. Capacitor element 3 has an anode foil 5, a cathode foil 7, and a separator 6, which are formed in a long strip shape. Capacitor element 3 is formed by rolling anode foil 5 and cathode foil 7 into a cylindrical shape with separator 6 interposed therebetween. In this way, anode foil 5 and cathode foil 7 form a pair of electrodes facing each other with separator 6 interposed therebetween.

[0028] The strip-shaped anode foil 5, cathode foil 7, and separator 6 are elongated in the winding direction (longitudinal direction), and the width in the direction perpendicular to the winding direction (transverse direction) is shorter than the length in the winding direction. The ends of the anode foil 5 or cathode foil 7 are fixed with tape 12. A lead terminal 8 is connected to the anode foil 5, and a lead terminal 9 is connected to the cathode foil 7.

[0029] The width of separator 6 in the short side direction (axial direction) is formed to be larger than the width of anode foil 5 and cathode foil 7 in the short side direction. As a result, separator 6 protrudes upward (toward end wall portion 2a) and downward (toward opening 2b) relative to anode foil 5 and cathode foil 7, thereby preventing a short circuit between anode foil 5 and cathode foil 7.

[0030] The anode foil 5 and the cathode foil 7 are primarily made of aluminum, and their surfaces are expanded by etching. The anode foil 5 may be made of a valve metal such as tantalum, niobium, or titanium. The anode foil 5 has a dielectric oxide film formed on its surface by chemical conversion. The cathode foil 7 may have a natural oxide film formed on its surface, or a dielectric oxide film formed by chemical conversion.

[0031] The separator 6 is made of fibers such as cellulose, polyethylene terephthalate, aramid, etc. To maintain stability at high temperatures (for example, 150° C.), the separator 6 preferably contains synthetic fibers.

[0032] An electrolytic solution, in which an electrolyte is dissolved in a solvent, is held between the anode foil 5 and the cathode foil 7 of the capacitor element 3. By immersing the capacitor element 3 in the electrolytic solution for a predetermined period of time, the electrolytic solution permeates the separator 6 and is held between the anode foil 5 and the cathode foil 7. The electrolytic solution essentially functions as a cathode. Furthermore, the electrolytic solution can repair defects in the oxide films of the anode foil 5 and the cathode foil 7.

[0033] At least one of the solvent and additive of the electrolyte is formed from a hydrophilic compound, and the sealing member deterioration inhibitor described below is incompatible with this hydrophilic compound.

[0034] The electrolyte dissociates into ions when dissolved in a solvent to exhibit electrical conductivity, and salts containing anions, salts containing anions and cations, etc. are used. Specifically, organic amine salts of boric acid compounds or carboxylic acid compounds are used as the electrolyte. Examples of boric acid compounds that can be used include boric acid, borodisalic acid, borodiglycolic acid, and borodisalicylic acid. Examples of carboxylic acids that can be used include phthalic acid, fumaric acid, adipic acid, maleic acid, and hydroxynitrobenzoic acid. Examples of organic amines that can be used include secondary organic amines, tertiary organic amines, quaternary organic amines, and imidazole compounds.

[0035] The solvent for the electrolyte is a high-boiling solvent with a boiling point of 150° C. or higher. Examples of the solvent include γ-butyrolactone, sulfolane, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, and derivatives thereof.

[0036] It is more preferable to use a hydrophilic compound as at least a part of the solvent, such as sulfolane, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, or derivatives thereof.

[0037] These hydrophilic compound solvents reduce the solubility of the sealant deterioration inhibitor (described later) in the electrolyte. Therefore, even if a 10-fold amount of hydrophilic compound solvent is used relative to the amount of sealant deterioration inhibitor, a portion of the sealant deterioration inhibitor remains undissolved. In other words, the sealant deterioration inhibitor is not soluble in the hydrophilic compound solvent and is incompatible with it.

[0038] Furthermore, the hydrophilic compound preferably accounts for 50% by weight or more of the solvent, more preferably 80% by weight or more, and even more preferably 90% by weight or more. This makes the sealant deterioration inhibitor incompatible with the electrolytic solution containing the hydrophilic compound, resulting in the electrolytic solution not dissolving the sealant deterioration inhibitor or reducing the solubility of the sealant deterioration inhibitor. As a result, a portion of the sealant deterioration inhibitor remains undissolved in the electrolytic solution. This allows the electrolytic solution to maintain a high electrical conductivity and facilitates penetration of the sealant deterioration inhibitor into the sealant 4.

[0039] To use the electrolytic capacitor 1 in a high-temperature environment of 150°C or higher, it is more preferable that the electrolyte contains at least 95% of solvents with a boiling point of 180°C or higher. Furthermore, assuming that the electrolytic capacitor 1 will be temporarily used in a high-temperature environment of up to about 175°C, it is even more preferable that the electrolyte contains at least 95% of solvents with a boiling point of 205°C or higher. This allows the electrolytic capacitor 1 to have a long life even in a high-temperature environment exceeding 150°C when used in combination with a seal deterioration inhibitor.

[0040] Examples of solvents with a boiling point of 205° C. or higher include sulfolane, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, and derivatives thereof. Among these, the use of diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, or derivatives thereof can improve the repairability and voltage resistance of the dielectric oxide film.

[0041] The electrolyte may also contain additives such as nitro compounds, solid hydrophilic compounds, hydrophilic antioxidants, voltage resistance improvers (such as polyalkylene glycols), sugars, glycerin, polyglycerin, derivatives thereof, phosphate esters, and gas absorbents.

[0042] Nitro compounds are compounds containing a nitro group, and examples of such compounds include dinitrobenzene, p-nitrophenol, m-nitroacetophenone, and hydroxynitrobenzoic acid. Nitro compounds can absorb gases generated from the cathode foil.

[0043] The additive consisting of a solid hydrophilic compound may be added to the solvent of the hydrophilic compound or to a lipophilic solvent such as gamma-butyrolactone. The additive consisting of a solid hydrophilic compound makes the sealant deterioration inhibitor incompatible with the electrolyte containing the hydrophilic compound, resulting in the electrolyte not dissolving the sealant deterioration inhibitor or reducing its solubility. As a result, a portion of the sealant deterioration inhibitor remains undissolved in the electrolyte containing the hydrophilic compound. Examples of hydrophilic compounds used as additives include polyethylene glycol with a molecular weight of 1,000 or more.

[0044] The hydrophilic antioxidant does not easily permeate into sealing body 4, and therefore can be retained in capacitor element 3 for a long period of time, thereby preventing oxidation of the electrolyte and separator 6.

[0045] The electrolyte preferably occupies 80% or more by volume of the voids in capacitor element 3. This allows electrolytic capacitor 1 to have a longer life.

[0046] A sealant deterioration inhibitor is also disposed inside the main case 2 of the electrolytic capacitor 1. The sealant deterioration inhibitor is a compound that is soluble in a lipophilic solvent but is incompatible with the hydrophilic compound contained in the electrolyte. The sealant deterioration inhibitor in the main case 2 penetrates into the sealant 4 through the gaps between the molecules of the sealant 4.

[0047] The sealant deterioration inhibitor is a compound that remains partially insoluble in, for example, 10 times the amount of hydrophilic solvent, and can be selected as a compound that is soluble in a lipophilic solvent. Examples of lipophilic solvents include γ-butyrolactone, diethylene glycol monobutyl ether acetate, and n-hexane. Compounds that are soluble in lipophilic solvents have a solubility parameter (SP value) close to that of the rubber sealant 4, and can therefore be used as a sealant deterioration inhibitor that quickly penetrates the sealant 4.

[0048] The sealant deterioration inhibitor may be dissolved in a hydrophobic solvent. The hydrophobic solvent may be a solvent that is not soluble in a hydrophilic solvent. If the sealant deterioration inhibitor is solid at room temperature, dissolving it in a hydrophobic solvent can improve its permeability into the sealant 4.

[0049] Examples of sealant deterioration inhibitors that can be used include terpenoids such as fat-soluble vitamins having an isoprene skeleton in the molecule (including cases where the main chain of the isoprene skeleton has a single bond or double bond or a cyclic structure), unsaturated fatty acids, polyglycerol esters containing an unsaturated fatty acid group in the molecule, saturated fatty acids, and derivatives of these. 2,2'-methylenebis(4-ethyl-6-tert-butylphenol) can also be used as a sealant deterioration inhibitor that is solid at room temperature.

[0050] Examples of fat-soluble vitamins include vitamin A, vitamin D, vitamin E, and vitamin K. Vitamin A is a compound with a carotenoid skeleton, and examples include retinol, β-carotene, α-carotene, β-cryptoxanthin, and astaxanthin. Vitamin D includes vitamin D2 and vitamin D3. Vitamin E includes tocopherols (α-tocopherol, β-tocopherol, γ-tocopherol, and δ-tocopherol) and tocotrienols (α-tocotrienol, β-tocotrienol, γ-tocotrienol, and δ-tocotrienol). Vitamin K includes vitamin K1, vitamin K2, and menaquinone 7.

[0051] These fat-soluble vitamins are terpenoids with an isoprene skeleton in their molecules, and have a strong affinity with the rubber seal 4. For this reason, it is preferable to use fat-soluble vitamins as seal deterioration inhibitors, as this improves permeability and retention in the seal 4. The number of isoprene units in fat-soluble vitamins is preferably two or more, and more preferably three or more. Vitamin A and vitamin E are more preferable because of their strong antioxidant effects.

[0052] When the rubber that forms the sealing body 4 is exposed to high temperatures (e.g., 150°C) during use in the presence of moisture and oxygen, some of its components oxidize or thermally decompose, causing it to shrink and crack. When cracks occur in the sealing body 4, the effective thickness of the rubber is reduced, deteriorating the sealing performance. The sealing body deterioration inhibitor disposed inside the main case 2 is supplied to the sealing body 4 and penetrates into the interior of the sealing body 4 through the gaps between the molecules of the sealing body 4. This reduces the penetration of oxygen and moisture, thereby suppressing deterioration of the sealing body 4.

[0053] Furthermore, the hydrophilic compound contained in the electrolyte can reduce the amount of sealant deterioration inhibitor, which is incompatible with the hydrophilic compound, that penetrates into the capacitor element 3. This makes it easier for the sealant deterioration inhibitor to penetrate into the sealant 4, and even in high-temperature environments during use of the electrolytic capacitor 1, the sealant deterioration inhibitor can quickly penetrate into the sealant 4 and reliably prevent deterioration of the sealant 4. This can extend the life of the electrolytic capacitor 1. Note that a portion of the sealant deterioration inhibitor may be dissolved in the electrolyte so that the sealant deterioration inhibitor gradually penetrates into the sealant 4 via the separator 6.

[0054] Furthermore, since the amount of sealing body deterioration inhibitor that penetrates into the inside of the capacitor element 3 can be reduced, it is possible to increase the amount of electrolyte impregnated into the capacitor element 3. As a result, the ESR of the electrolytic capacitor 1 can be reduced.

[0055] The molecular weight of the sealant deterioration inhibitor is preferably 3000 or less for good permeability, and more preferably 2000 or less. The molecular weight of the sealant deterioration inhibitor is also preferably 200 or more for good retention of the sealant 4, and more preferably 250 or more, and even more preferably 300 or more. By using a sealant deterioration inhibitor in this molecular weight range, permeability into the sealant 4 is improved and the sealant deterioration inhibitor effect can be maintained for a long period of time. Two or more sealant deterioration inhibitors with different molecular weights can be used to adjust the permeability into the sealant 4 and the durability.

[0056] Furthermore, because the sealant deterioration inhibitor reduces the amount of oxygen and moisture that permeates sealant 4, the sealant deterioration inhibitor in the electrolyte is maintained in the capacitor element 3 for a long period of time in a state where it is less susceptible to deterioration such as oxidation. As a result, deterioration of sealant 4 can be suppressed for a long period of time.

[0057] Although the sealant deterioration inhibitor is effective in suppressing deterioration of sealant 4 even if it does not reach the outer surface of sealant 4, it is more preferable if it reaches the outer surface of sealant 4. This makes it possible to suppress deterioration of sealant 4 even on the outer surface of sealant 4, where cracks are likely to occur, and further suppresses the intrusion of oxygen and moisture.

[0058] At this time, the sealant deterioration inhibitor may form an oil film on the outer surface of the sealant 4, or may form a coating that solidifies through oxidation upon contact with oxygen in the air. The coating further inhibits the penetration of oxygen and moisture. Furthermore, although silicone rubber and fluororubber are less airtight than butyl rubber, providing a coating can improve their airtightness.

[0059] The weight ratio of the sealant deterioration inhibitor in the sealant 4 to the sealant 4 is preferably 0.1% to 25% by weight. If the weight ratio of the sealant deterioration inhibitor in the sealant 4 to the sealant 4 is lower than 0.1% by weight, the gaps between the molecules of the sealant 4 cannot be sufficiently filled, and the effect of inhibiting moisture penetration cannot be obtained.

[0060] If the weight ratio of the sealant deterioration inhibitor in the sealant 4 is higher than 25% by weight, the sealant 4 may soften or change shape. This will deteriorate the sealing performance of the sealant 4 and make it impossible to suppress moisture penetration. It is more preferable that the hardness (durometer hardness) of the sealant 4 after penetration of the sealant deterioration inhibitor is 70 or more on either side of the sealant 4, as this will allow high sealing performance to be maintained.

[0061] The thickness of the sealing member 4 is related to the evaporation rate of the electrolyte, the amount of moisture permeation, and the permeability of the sealing member deterioration inhibitor. To maintain low evaporation of the electrolyte and low moisture permeation, the thickness of the sealing member 4 is preferably 1.4 mm or more. Furthermore, to allow the sealing member deterioration inhibitor to permeate the entire sealing member 4 and prevent cracks from occurring, the thickness of the sealing member 4 is preferably 7 mm or less.

[0062] The sealant deterioration inhibitor that has permeated almost the entire surface of the sealant 4 on the capacitor element 3 side can be confirmed by the following method. First, the sealant 4, from which the electrolyte solution has been wiped off, is cut into pieces, for example, 1 mm thick and 1 mm wide in the radial direction from the outer periphery, and then crushed. Next, the crushed sample is extracted with an organic solvent, and the solution is analyzed using liquid chromatography-mass spectrometry (LC-MS), gas chromatography-mass spectrometry (GC-MS), or the like. This allows the sealant deterioration inhibitor to be detected.

[0063] The electrolytic capacitor 1 is manufactured by sequentially performing an element formation process, an element housing process, a sealing body attachment process, a molding process, and a repair process. The element formation process further includes an anodization process, a terminal formation process, a winding process, and an electrolyte impregnation process, in that order.

[0064] In the anodizing process, the surface of the anode foil 5 is first roughened by etching. The etched anode foil 5 is then anodized in an anodizing solution, forming a dielectric oxide film on the surface. In the terminal formation process, lead terminals 8 and 9 are joined to one end of the anode foil 5 and cathode foil 7 by crimping. In the winding process, the anode foil 5 and cathode foil 7 are wound with separator 6 interposed between them, and the ends are fixed with tape 12.

[0065] In the electrolyte impregnation step, the capacitor element 3 is immersed in the electrolyte for a predetermined period of time. This results in a capacitor element 3 impregnated with the electrolyte. The immersion time for the capacitor element 3 varies depending on the size, but can be, for example, from 1 second to several hours, and preferably from 1 second to 5 minutes. The immersion temperature for the capacitor element 3 is not particularly limited, but can be, for example, from 0°C to 80°C, and preferably from 10°C to 40°C.

[0066] In the element housing process, the capacitor element 3 is inserted into the main case 2 through the opening 2b and housed therein. At this time, the inside of the main case 2 is filled with a sealant deterioration inhibitor, and the sealant deterioration inhibitor is disposed between the capacitor element 3 and the main case 2.

[0067] In the element formation process, capacitor element 3 may be immersed in an emulsion in which a sealant deterioration inhibitor is dispersed in an electrolyte, and the step of filling the sealant deterioration inhibitor in the element housing process may be omitted. This increases the amount of sealant deterioration inhibitor that penetrates into capacitor element 3, but the sealant deterioration inhibitor flows down separator 6 and is disposed between capacitor element 3 and sealant 4.

[0068] In the sealing body attachment process, sealing body 4 is inserted into main case 2, which houses capacitor element 3, from opening 2b side and attached. Lead terminals 8, 9 of capacitor element 3 are inserted into through holes 4a, 4b of sealing body 4 by press-fitting. At this time, the sealing body deterioration inhibitor filled inside main case 2 is disposed between capacitor element 3 and sealing body 4. Even if main case 2 is not filled to capacity with sealing body deterioration inhibitor, the sealing body deterioration inhibitor will be disposed between capacitor element 3 and sealing body 4 by placing electrolytic capacitor 1 with end wall portion 2a facing upward.

[0069] In the forming process, a protrusion 13 that protrudes toward the inner surface of the main case 2 is formed by drawing, and a curling process is performed on the open edge to form a folded portion 14. In the repair process, the dielectric oxide film formed on the anode foil 5 and the cathode foil 7 is repaired. The repair process is performed, for example, by applying the rated voltage of the capacitor between the lead terminals 8 and 9 for 30 minutes in a high-temperature environment of 125°C. At this time, by placing the sealing body 4 on the bottom side, the sealing body deterioration inhibitor can be permeated into the sealing body 4. Furthermore, the high-temperature environment at this time promotes the permeation of the sealing body deterioration inhibitor into the interior of the sealing body 4.

[0070] According to this embodiment, an electrolytic solution containing an electrolyte and a hydrophilic compound is held between the anode foil 5 and the cathode foil 7, and a sealant deterioration inhibitor that is incompatible with the hydrophilic compound is disposed inside the main case 2. This allows the sealant deterioration inhibitor to quickly permeate into the sealant 4, thereby suppressing deterioration of the sealant 4 even in high-temperature environments, resulting in an electrolytic capacitor 1 with a long life and low ESR.

[0071] Furthermore, the sealant deterioration inhibitor is a terpenoid, an unsaturated fatty acid, a polyglycerol ester containing an unsaturated fatty acid group in the molecule, a saturated fatty acid, or a derivative thereof, which makes it easy to realize a sealant deterioration inhibitor that is incompatible with hydrophilic compounds.

[0072] Furthermore, the hydrophilic compound forms at least a part of the solvent of the electrolytic solution in which the electrolyte is dissolved, and has a boiling point of 180° C. or higher, which makes it easy to realize an electrolytic capacitor 1 with a long life even in high-temperature environments exceeding 150° C.

[0073] Furthermore, if the hydrophilic compound forming the solvent of the electrolyte has a boiling point of 205° C. or higher, it is possible to easily realize an electrolytic capacitor 1 with a long life even in a higher temperature environment.

[0074] In addition, the hydrophilic compound forming the solvent of the electrolyte solution includes sulfolane, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, or a derivative thereof, which makes it easy to realize a solvent for the hydrophilic compound with which the sealer deterioration inhibitor is incompatible.

[0075] Furthermore, since the hydrophilic compound contained in the electrolyte solution contains polyethylene glycol with a molecular weight of 1000 or more, the addition of the hydrophilic compound makes it easy to realize an electrolyte solution incompatible with the sealing body deterioration inhibitor.

[0076] Second Embodiment Next, an electrolytic capacitor 1 according to a second embodiment will be described. In the electrolytic capacitor 1 according to this embodiment, the capacitor element 3 is formed as a hybrid type in which a solid electrolyte and an electrolytic solution similar to that of the first embodiment are held between the anode foil 5 and the cathode foil 7. Other parts are similar to those of the first embodiment.

[0077] The solid electrolyte is made of a conductive polymer and is provided as a solid electrolyte layer on at least a portion of the surface of the anode foil 5, the cathode foil 7, and the separator 6. The conductive polymer is a polymer of pyrrole, thiophene, aniline, or a derivative thereof. The conductive polymer is doped with a compound having a sulfonic acid group, such as polystyrene sulfonic acid, as a dopant. The conductive polymer may be of the self-doping type within the molecule, due to the sulfonic acid group being included as a substituent on the side chain.

[0078] A solid electrolyte layer is formed by impregnating capacitor element 3 with a dispersion liquid in which a conductive polymer is dispersed in water or an aqueous solution of a conductive polymer, and then drying the impregnated capacitor element 3.

[0079] The electrolyte held between the anode foil 5 and the cathode foil 7 is formed in the same manner as in the first embodiment. That is, an organic amine salt of a boric acid compound or a carboxylic acid compound is used as the electrolyte. Boric acid compounds and aromatic carboxylic acids are preferred because they provide a long life for the hybrid-type electrolytic capacitor 1.

[0080] The solvent for the electrolyte is a high-boiling solvent with a boiling point of 150° C. or higher. Examples of the solvent include γ-butyrolactone, sulfolane, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, and derivatives thereof.

[0081] As the solvent for the hydrophilic compound, it is more preferable to use sulfolane, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polyglycerin, or derivatives thereof.

[0082] Furthermore, it is even more preferable to use ethylene glycol, diethylene glycol, polyethylene glycol, polyglycerin, or their derivatives as the solvent for the hydrophilic compound. These solvents contain hydroxyl groups and ether groups, which improve the repairability and voltage resistance of the dielectric oxide film, and also have high affinity with conductive polymers and a high boiling point. This allows the ESR of the electrolytic capacitor 1 to be kept low for a long period of time.

[0083] The electrolytic solution covers at least a portion of the solid electrolyte layer, preventing contact between oxygen and the solid electrolyte and thereby preventing oxidation degradation of the solid electrolyte. It is preferable that the electrolytic solution covers substantially the entire solid electrolyte in capacitor element 3, but even if the solvent in the electrolytic solution evaporates, the additives to the electrolytic solution remain, thereby preventing oxidation degradation of the solid electrolyte.

[0084] The electrolyte solution may contain additives similar to those in the first embodiment. Polyethylene glycol having a molecular weight of 1000 or more may be added as an additive to the hydrophilic compound. Furthermore, the electrolyte solution may contain an antioxidant or the like that is soluble in the solvent of the hydrophilic compound. This allows the electrolyte solution to cover at least a portion of the solid electrolyte layer, thereby suppressing oxidative degradation of the solid electrolyte layer.

[0085] It is preferable that the antioxidant soluble in the hydrophilic compound solvent does not inhibit the restoration of the dielectric oxide film by oxidation. Therefore, the antioxidant content in the electrolyte is preferably 10% or less, more preferably 3% or less. By incorporating an incompatible sealant deterioration inhibitor in the electrolyte and an antioxidant compatible with the electrolyte, the effects of inhibiting sealant deterioration and inhibiting oxidation of the conductive polymer work synergistically, thereby suppressing ESR degradation over the long term.

[0086] The manufacturing process of the hybrid electrolytic capacitor 1 of this embodiment includes the manufacturing process of the electrolytic capacitor 1 of the first embodiment plus an element formation step and a solid electrolyte layer formation step, which are performed between the winding step and the electrolyte solution impregnation step.

[0087] In the element formation process, the capacitor element 3 is immersed in a formation solution and anodized, thereby repairing the dielectric oxide film that was damaged during the winding process and other processes.

[0088] In the solid electrolyte layer formation process, first, the capacitor element 3 is immersed in a dispersion liquid in which conductive polymer particles or their aggregates are dispersed in a dispersion medium, thereby impregnating the dispersion liquid into the capacitor element 3. Next, the capacitor element 3 is dried at high temperature to remove the dispersion medium, and the solid electrolyte layer is formed.

[0089] The dispersion medium should preferably not dissolve the conductive polymer, and water is more preferable in consideration of ease of handling and dispersibility. For example, the capacitor element 3 can be impregnated with a dispersion liquid in which polyethylenedioxythiophene particles are dispersed in water by immersing the capacitor element 3 under reduced pressure. At this time, the dispersion medium may contain a dopant agent. The dispersion medium can also be removed by drying the capacitor element 3 at 100°C to 200°C, for example.

[0090] In the solid electrolyte layer formation step, the solid electrolyte layer may be formed by oxidatively polymerizing a polymerizable monomer. That is, the capacitor element 3 is impregnated with a polymerizable monomer (e.g., ethylenedioxythiophene monomer). Next, the capacitor element 3 is immersed in an oxidizing agent (e.g., an ethanol solution of iron paratoluenesulfonate) to perform oxidative polymerization. This forms a solid electrolyte layer made of a conductive polymer (e.g., polyethylenedioxythiophene).

[0091] According to this embodiment, as in the first embodiment, a solid electrolyte and a liquid (electrolytic solution) containing a hydrophilic compound are held between the anode foil 5 and the cathode foil 7, and a sealant deterioration inhibitor that is incompatible with the hydrophilic compound is disposed inside the main case 2. This allows the sealant deterioration inhibitor to quickly permeate into the sealant 4, thereby suppressing deterioration of the sealant 4 even in high-temperature environments, resulting in an electrolytic capacitor 1 with a long life and low ESR.

[0092] Furthermore, since the hydrophilic compound forms at least a part of the solvent of the electrolyte and has a boiling point of 180°C or higher, the electrolytic capacitor 1 can have a long life even in a high-temperature environment exceeding 150°C.

[0093] <Third embodiment> Next, a third embodiment will be described. In the electrolytic capacitor 1 of this embodiment, the capacitor element 3 holds a solid electrolyte and a predetermined functional liquid. The other parts are the same as those of the second embodiment.

[0094] The solid electrolyte is made of a conductive polymer similar to that of the second embodiment, which can reduce the ESR of the electrolytic capacitor 1.

[0095] The functional liquid held in the capacitor element can be a liquid similar to the solvent of the electrolyte solution in Embodiment 2. That is, the functional liquid can be a hydrophilic compound such as sulfolane, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, or a derivative thereof.

[0096] Using polyalkylene glycol as the functional liquid can improve the withstand voltage of the electrolytic capacitor 1. Using a compound containing a hydroxyl group, such as sugar or glycerin, as the functional liquid can improve the conductivity of the solid electrolyte layer.

[0097] Furthermore, as the functional liquid, a hydrophilic compound such as polyethylene glycol having a molecular weight of 1000 or more can be added to a lipophilic liquid such as γ-butyrolactone.

[0098] According to this embodiment, as in the first and second embodiments, a solid electrolyte and a liquid (functional liquid) containing a hydrophilic compound are held between the anode foil 5 and the cathode foil 7, and a sealant deterioration inhibitor that is incompatible with the hydrophilic compound is disposed inside the main case 2. This allows the sealant deterioration inhibitor to quickly permeate into the sealant 4, thereby suppressing deterioration of the sealant 4 even in high-temperature environments, resulting in an electrolytic capacitor 1 with a long life and low ESR.

[0099] <Fourth embodiment> Next, a fourth embodiment will be described. In the electrolytic capacitor 1 of this embodiment, the capacitor element 3 holds a solid electrolyte and a predetermined room temperature solid substance. The other parts are the same as those of the second embodiment.

[0100] The solid electrolyte is made of a conductive polymer similar to that of the second embodiment, which can reduce the ESR of the electrolytic capacitor 1.

[0101] The room temperature solid substance is solid at room temperature (e.g., 30°C), and the electrolyte is dissolved in a solvent that melts in an environment that is higher than room temperature (e.g., 50°C or higher) during use of the electrolytic capacitor 1. As a result, the room temperature solid substance is solid below room temperature, and becomes a liquid electrolyte in an environment that is higher than room temperature.

[0102] The solvents contained in substances that are solid at room temperature are made up of hydrophilic compounds. Examples of solvents for hydrophilic compounds include polyethylene glycol and sugars. These are solid at room temperature and have a melting point of 50°C or higher.

[0103] Examples of polyethylene glycol that can be used include PEG2000 (melting point 51°C), PEG4000 (melting point 56°C), PEG6000 (melting point 58°C), PEG10000 (melting point 62°C), and PEG20000 (melting point 63°C). PEG2000 refers to polyethylene glycol with an average molecular weight of 2000. The same applies to PEG4000, PEG6000, PEG10000, and PEG20000.

[0104] As the sugar, xylitol (melting point 92°C) and sorbitol (melting point 95°C) can be used.

[0105] The electrolyte contained in the room-temperature solid material can be an acid or a base. Examples of the acid that is the electrolyte contained in the room-temperature solid material include malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, decanedicarboxylic acid, tartronic acid, fumaric acid, maleic acid, citraconic acid, malic acid, tartaric acid, phthalic acid, nitrophthalic acid, citric acid, tricarbanilic acid, pyromellitic acid, boric acid, phosphoric acid, borodisalicylic acid, borodiglycolic acid, trinitrophenol, hydroxynitrophenol, and sulfosalicylic acid.

[0106] Examples of the base that is an electrolyte contained in the room temperature solid substance include ammonia, monoethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, benzylamine, naphthylamine, morpholine, aniline, acetanilide, phenanthroline, caffeine, and imidazole.

[0107] When electrolytic capacitor 1 having the above configuration is placed in a high-temperature environment during use, the room-temperature solid substance liquefies, and a solvent for the hydrophilic compound is placed in capacitor element 3. This reduces the amount of sealant deterioration inhibitor that penetrates into capacitor element 3, making it easier for the sealant deterioration inhibitor to penetrate into seal 4. Furthermore, because the amount of sealant deterioration inhibitor inside capacitor element 3 is small, the amount of room-temperature solid substance that is impregnated can be increased. This reduces the ESR of electrolytic capacitor 1 and extends its lifespan.

[0108] A room temperature solid substance is produced by a melting process, a solidification process, and a pulverization process. In the melting process, a solvent is placed in a container and heated to a temperature above the melting point of the solvent. As mentioned above, the melting point varies depending on the solvent. Then, an electrolyte is added to the liquefied solvent to create a solution in which the electrolyte is uniformly dissolved in the solvent. Heating in the melting process can be performed using a heater or a high-frequency heating device.

[0109] In the solidification process, the container is cooled to room temperature to solidify the room-temperature solid material. At this time, the room-temperature solid material has the electrolyte dispersed within the solidified solvent. In the pulverization process, the room-temperature solid material solidified in the solidification process is pulverized to form a powder room-temperature solid material.

[0110] The electrolytic capacitor 1 of this embodiment is manufactured in the same manner as in the second embodiment. In the element housing step, powder of a room-temperature solid material is housed in the main case 2 and heated to a temperature equal to or higher than the melting point of the solvent of the room-temperature solid material. This melts the room-temperature solid material inside the main case 2. Then, the capacitor element 3 is housed in the main case 2.

[0111] At this time, the liquid substance that is solid at room temperature penetrates into the interior of capacitor element 3 due to capillary action. As a result, the substance that is solid at room temperature is disposed between anode foil 5 and cathode foil 7 and between capacitor element 3 and main case 2. Then, main case 2 containing capacitor element 3 is cooled to solidify the substance that is solid at room temperature, after which a seal deterioration inhibitor is filled into main case 2 and the process moves to the next seal attachment process.

[0112] According to this embodiment, as in the first to third embodiments, a room-temperature solid substance containing a solid electrolyte and a hydrophilic compound is held between anode foil 5 and cathode foil 7, and a sealant deterioration inhibitor that is incompatible with the hydrophilic compound is disposed inside main case 2. This allows the sealant deterioration inhibitor to quickly permeate into seal 4, thereby suppressing deterioration of seal 4 even in high-temperature environments, resulting in an electrolytic capacitor 1 with a long life and low ESR.

[0113] Furthermore, because the hydrophilic compound forms at least a part of the solvent for the substance that is solid at room temperature, the hydrophilic compound, which is liquid at temperatures higher than room temperature, inhibits the sealant deterioration inhibitor from penetrating into the capacitor element 3. This allows the sealant deterioration inhibitor to quickly penetrate into the sealant 4 in a high-temperature environment.

[0114] Furthermore, since the hydrophilic compound is PEG2000, PEG4000, PEG6000, PEG10000, PEG20000, xylitol or sorbitol, the sealer deterioration inhibitor can easily be an incompatible hydrophilic compound.

[0115] In the first to fourth embodiments, the electrodes (anode foil 5 and cathode foil 7) of capacitor element 3 are wound facing each other with separator 6 interposed therebetween, but the pair of electrodes facing each other with separator interposed therebetween may also be flat.

[0116] Examples formed for evaluating the electrolytic capacitor 1 of each embodiment will be described below.

[0117] Example 1 is formed by the electrolytic capacitor 1 of the first embodiment. The solvent of the electrolyte in Example 1 is ethylene glycol, and the sealant deterioration inhibitor is α-tocopherol, which is incompatible with ethylene glycol. The weight ratio of the electrolyte to the sealant deterioration inhibitor is 75:25. The weight ratio of the solvent to the solute in the electrolyte is 85:15. The sealant 4 is formed from butyl rubber.

[0118] Example 2 is formed by the electrolytic capacitor 1 of the second embodiment. The solvent of the electrolyte in Example 2 is sulfolane, and the sealant deterioration inhibitor is α-tocopherol, which is incompatible with sulfolane. The weight ratio of the electrolyte to the sealant deterioration inhibitor is 75:25. The weight ratio of the solvent to the solute in the electrolyte is 85:15. The sealant 4 is formed from butyl rubber.

[0119] Example 3 is formed using the electrolytic capacitor 1 of the third embodiment. The functional liquid in Example 3 is triethylene glycol, and the sealant deterioration inhibitor is α-tocopherol, which is incompatible with triethylene glycol. The weight ratio of the functional liquid to the sealant deterioration inhibitor is 75:25. The sealant 4 is formed from butyl rubber.

[0120] [Comparative Example 1] For comparison, comparative examples were also prepared. In comparative example 1, γ-butyrolactone was used instead of the electrolyte solution in example 1. The sealer deterioration inhibitor α-tocopherol is compatible with γ-butyrolactone.

[0121] Comparative Example 2 In Comparative Example 2, γ-butyrolactone was used instead of the electrolyte solution of Example 2. The α-tocopherol used as the sealer deterioration inhibitor is compatible with γ-butyrolactone.

[0122] Comparative Example 3 In Comparative Example 3, a polyethylene glycol-polypropylene glycol copolymer was used instead of the electrolyte solution in Example 2. The α-tocopherol used as the sealer deterioration inhibitor is compatible with the polyethylene glycol-polypropylene glycol copolymer.

[0123] Comparative Example 4 Comparative Example 4 has a configuration in which the sealant deterioration inhibitor is omitted from electrolytic capacitor 1 of Example 2.

[0124] Comparative Example 5 Comparative Example 5 has a configuration in which the sealant deterioration inhibitor is omitted from electrolytic capacitor 1 of Example 3.

[0125] Comparative Example 6 Comparative Example 6 has a configuration in which the sealant deterioration inhibitor is omitted from electrolytic capacitor 1 of Comparative Example 2.

[0126] Comparative Example 7 Comparative Example 7 has a configuration in which the sealant deterioration inhibitor is omitted from electrolytic capacitor 1 of Comparative Example 3.

[0127] In addition, in accordance with Evaluation Test 1 described later, samples were prepared in which the sealing body deterioration inhibitor was omitted from Example 1 and Comparative Example 1.

[0128] The following evaluation tests 1 to 3 were performed on the electrolytic capacitor 1 of each of the above examples and comparative examples. Evaluation test 1 measured the ratio of the characteristics of Example 1 and Comparative Example 1 to the characteristics of a sample that did not contain a sealant degradation inhibitor. Specifically, the capacitance, tan δ, and ESR characteristics of Example 1, Comparative Example 1, and these samples that did not contain a sealant degradation inhibitor were measured. Then, each characteristic of the sample that did not contain a sealant degradation inhibitor was set to 1, and the characteristics of Example 1 and Comparative Example 1 were expressed as a ratio.

[0129] Evaluation tests 2 and 3 used Examples 2-3 and Comparative Examples 2-7 to examine the permeability of the sealant deterioration inhibitor into the sealant 4. Specifically, electrolytic capacitor 1 was placed in an atmosphere at 175°C with the outer surface of sealant 4 facing up, and the weight change and step change rate of sealant 4 after 500 hours of high-temperature storage were measured. Evaluation tests 2 and 3 were performed simultaneously using the same sample, with five samples for each Example and Comparative Example.

[0130] The weight change of the sealing member 4 in Evaluation Test 2 was calculated by subtracting the weight of the sealing member 4 before assembly of the electrolytic capacitor 1 from the weight of the sealing member 4 taken out by disassembling the electrolytic capacitor 1 after the test.

[0131] The step amount used to determine the step change rate of sealing body 4 in evaluation test 3 was the height distance (average value of multiple points) from a reference plane in the area between lead terminals 8 and 9. Here, with the outer surface of sealing body 4 facing up, the top surface of folded portion 14 of main case 2 was used as the reference plane, and the distance from the reference plane was measured using a three-dimensional measuring machine.

[0132] A positive value of the step change rate indicates a decrease in the step amount, and a negative value indicates an increase in the step amount. A step change rate greater than +100% indicates that the surface of sealing body 4 protrudes from the reference surface, resulting in a deterioration in sealing performance.

[0133] [Table 1]

[0134] Table 1 shows the results of Evaluation Test 1. Table 1 shows that Comparative Example 1, which contains a sealant degradation inhibitor, shows greater deterioration in characteristics than the case where the sealant degradation inhibitor is omitted. In contrast, Example 1 shows that even though the sealant degradation inhibitor is added, the amount of sealant degradation inhibitor dissolved in the electrolyte is small, so the effect on the conductivity of the electrolyte is suppressed. This confirmed that the deterioration of the characteristics of electrolytic capacitor 1 can be suppressed.

[0135] [Table 2]

[0136] Table 2 shows the results of Evaluation Test 2, and Fig. 5 shows the results of Evaluation Test 3. Fig. 6 shows the state of sealing body 4 of Example 3 after Evaluation Tests 2 and 3, and Fig. 7 shows the state of sealing body 4 of Comparative Example 5 after Evaluation Tests 2 and 3.

[0137] According to Table 2 and Figure 5, when the main case 2 contains a sealant degradation inhibitor, it is believed that the sealant degradation inhibitor penetrates into the sealant 4. This causes the weight of the sealant 4 to increase after the test, and the step change rate is a positive value. In contrast, when the main case 2 does not contain a sealant degradation inhibitor, the weight decreases, and the step change rate is a negative value. This causes the components of the sealant 4 to decompose or evaporate due to heat, causing the sealant 4 to shrink.

[0138] Furthermore, as shown in Figure 7, in Comparative Example 5, which did not contain a sealing body deterioration inhibitor in the main body case 2, it was observed that the step widened significantly after 500 hours at 175°C (the step change rate was negative), and the sealing body 4 shrunk, causing cracks.

[0139] In contrast, as shown in Figure 6, when a sealant deterioration inhibitor was contained in main case 2 (Example 3), it was visually observed that sealant 4 did not shrink and no cracks occurred on the outer surface of sealant 4. Because sealant 4 did not shrink, cracks were less likely to occur in sealant 4, and gaps were less likely to form between sealant 4 and lead terminals 8 and 9 and between sealant 4 and main case 2, so sealing performance was maintained.

[0140] Furthermore, if the weight change of sealing body 4 after 500 hours at 175°C was 13.18% or less, the step change rate was less than 100%, and no deterioration in sealing performance due to penetration of the sealing body deterioration inhibitor was observed. [Industrial Applicability]

[0141] The present invention can be used in automobiles, electronic devices, etc., in which electrolytic capacitors are mounted in circuits. [Explanation of symbols]

[0142] 1 electrolytic capacitor 2 Main unit case 2a End wall 2b opening 3 Capacitor elements 4 Sealing body 4a, 4b through hole 5 Anode foil 6 Separator 7 Cathode foil 8, 9 Lead terminal 12 Tape 13 Protrusion 14 Folded section 15 Seat board 15a, 15b through hole

Claims

1. An electrolytic capacitor comprising a capacitor element in which an anode foil and a cathode foil having a dielectric oxide film face each other with a separator interposed therebetween, a main case for accommodating the capacitor element, and a sealing member for sealing the main case, a functional liquid containing a hydrophilic compound and a solid electrolyte are held between the anode foil and the cathode foil; the hydrophilic compound is a compound having a hydroxyl group, A sealing body deterioration inhibitor incompatible with the hydrophilic compound is disposed inside the main body case, An electrolytic capacitor characterized in that the sealing body deterioration inhibitor is disposed in the main body case in a state incompatible with the hydrophilic compound in the capacitor element.

2. 2. The electrolytic capacitor according to claim 1, wherein the seal deterioration inhibitor is a terpenoid, an unsaturated fatty acid, a polyglycerin ester containing an unsaturated fatty acid group in the molecule, a saturated fatty acid, or a derivative thereof.

3. An electrolytic capacitor as described in claim 1 or claim 2, characterized in that the hydrophilic compound has a boiling point of 180°C or higher.

4. 4. The electrolytic capacitor according to claim 3, wherein the hydrophilic compound has a boiling point of 205° C. or higher.

5. An electrolytic capacitor as described in claim 3, characterized in that the compound having a hydroxyl group includes at least one of ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, sugar, or derivatives thereof.

6. An electrolytic capacitor as described in claim 1 or claim 2, characterized in that the compound having a hydroxyl group includes at least one of polyalkylene glycol, glycerin, and sugar.

7. An electrolytic capacitor as described in Claim 6, characterized in that the compound having a hydroxyl group includes at least a polyalkylene glycol.

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