JP2008098494A - Aluminum electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor which reduces impedance and prolongs the service life. <P>SOLUTION: The aluminum electrolytic capacitor comprises: a capacitor element 19 around which an anode foil 11 and a cathode foil 12 are wound while interposing a separator 13 therebetween, the anode foil 11 connecting an anode lead 15 to an aluminum foil formed with a dielectric oxide coating on its surface and the cathode foil 12 connecting a cathode lead 16 to the aluminum foil; a driving electrolytic solution 14 impregnated in the capacitor element 19; a bottomed metal case 18 for housing therein the capacitor element 19 impregnated with the driving electrolytic solution 14; and a sealing body 17 sealing an opening of the metal case 18. The driving electrolytic solution 14 is composed of an electrolyte composed of carboxylic acid and/or inorganic acid, and a mixed solvent of an organic solvent and water with pH settled within a range of 6.0 to 8.5. The separator 13 is composed of cellulosic fibers, the cellulosic fibers being obtained by bonding a thermally treated paper strength enhancer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aluminum electrolytic capacitor that can improve impedance characteristics, short-circuit failure rate, high heat resistance, etc., and can achieve long life and high reliability.

  In general, an aluminum electrolytic capacitor is formed by winding a separator between an anode foil and a cathode foil to create a capacitor element, and the capacitor element is immersed in a liquid driving electrolyte to drive as an electrolyte. The capacitor element impregnated with the electrolytic solution for driving, the capacitor element impregnated with the driving electrolytic solution is accommodated in a bottomed cylindrical metal case, and the opening of the metal case is sealed.

  As the driving electrolyte, ethylene glycol (EG), dimethylformamide (DMF), or γ-butyrolactone (GBL) is usually used as a solvent, and organic acids such as boric acid, ammonium adipate, and ammonium hydrogen maleate are used as these solvents. It is manufactured by infiltrating from both ends of the capacitor element using a melted material.

  In order to reduce the impedance of such an aluminum electrolytic capacitor, in the electrolytic solution, γ-butyrolactone is used as a solvent, and a driving electrolytic solution containing quaternary ammonium salt of phthalic acid or maleic acid as an electrolyte, or ethylene glycol and water as a solvent. A driving electrolyte solution having high electrical conductivity and stable at a high temperature is used as the driving electrolyte solution (see, for example, Patent Document 1 and Patent Document 2).

  On the other hand, separator materials have been improved to improve the impedance characteristics of aluminum electrolytic capacitors. However, if the separator is thinned or the density is reduced, the tensile strength is inevitably lowered, resulting in a short-circuit defect rate. Even if the short circuit does not occur, there is a problem that the short defect rate after being commercialized and marketed becomes high.

  Therefore, in order to reduce the short-circuit defect rate due to the separator, the thickness of the separator is increased, the density is increased, or in the case of the same density, the CSF (JIS P 8121) indicating the degree of beating of the raw material pulp. It is known that by reducing the value of (Canadian Standard Freeness), the fibers of the pulp become fibrillated and become finer, the resulting separator becomes dense, the tensile strength increases, and the short-circuit defect rate is improved. However, it has been found that the effect of these items on the equivalent series resistance (hereinafter referred to as ESR) is that the thicker the separator, the worse the ESR, and the higher the density, the quadratic, the ESR. ing. That is, in order to improve ESR, it is necessary to make the separator thinner and lower its density, contrary to the improvement of the short-circuit defect rate.

Therefore, in order to achieve both the objectives of improving the short defect rate and improving the ESR, as described above, the raw material of the separator has a fiber diameter of normal wood craft pulp, softwood wood pulp, manila hemp pulp, esparto pulp, etc. Attempts have been made to produce thin, low-density and dense separators by changing to smaller pulp (see, for example, Patent Document 3).
Japanese Patent Laid-Open No. 62-145715 JP 2000-228332 A Japanese Patent Laid-Open No. 08-273984

  In the above aluminum electrolytic capacitor, a driving electrolytic solution in which a quaternary ammonium salt of phthalic acid or maleic acid is dissolved in a γ-butyrolactone solvent as an electrolytic solution is used as a cathode when continuously energized in a humid atmosphere. A strong alkali component was generated at the portion, and in particular, there was a possibility that the driving electrolyte leaked out of the capacitor by eroding the cathode lead and the sealing body in contact with the cathode lead.

  In addition, since the driving electrolyte using γ-butyrolactone solvent has a flash point of around 100 ° C., an abnormal voltage or reverse voltage is applied to the aluminum electrolytic capacitor due to abnormal operation of the electronic equipment, and the safety valve is activated. It could not be said that there was no possibility of ignition when the electrolyte for one drive was ejected.

  On the other hand, a driving electrolyte using a mixed solvent of ethylene glycol and water as a solvent is effective in reducing impedance, but has long-term electrical performance at a temperature higher than the boiling point of water (100 ° C.), which is one of the solvent components. For example, in a rated voltage application test at a temperature of 110 ° C., the internal pressure rises due to the influence of a large amount of hydrogen gas resulting from the hydration reaction between aluminum and water. In the no-load standing test at a temperature of 110 ° C., there were problems such as an increase in the rate of change of the leakage current value after the test with respect to the initial leakage current value within 1000 hours.

  In order to solve these problems, for the purpose of suppressing the hydration reaction between the anode foil and the cathode foil and water, a method of adding various phosphorus compounds to the driving electrolyte, and the purpose of absorbing the generated hydrogen gas Methods such as adding various nitro compounds as gas absorbents have been proposed. However, even when these methods are used, a driving electrolyte solution having a high water content such that the water content exceeds 20% is used. It was difficult to maintain the electrical performance of the capacitor for a long time at a temperature of ℃ or higher (in a high voltage capacitor whose rated voltage exceeds 100 V, the dielectric oxide film is thick and strong. If an electrolytic solution having a water content of about 20 to 25% is used, the electric performance may be stable for about 1000 to 2000 hours at a temperature of 100 ° C. or higher. There are due to the thin oxide film, these problems have not been satisfactorily resolved).

  On the other hand, even if a low-density separator is used as the separator, the tensile strength of the separator is not sufficient, and it is likely that paper breakage is likely to occur during the manufacture of the capacitor element and when the separator is cut to a required width. Difficulties arise. Furthermore, there is a problem that the short circuit between the anode foil and the cathode foil or the withstand voltage characteristic deteriorates.

  An object of the present invention is to solve the problems of conventional aluminum electrolytic capacitors and to provide an aluminum electrolytic capacitor having a long life while reducing impedance.

  In order to achieve the above object, the present invention provides an anode foil having an anode lead connected to an aluminum foil having a dielectric oxide film formed on the surface and a cathode foil having a cathode lead connected to the aluminum foil. A wound capacitor element, a driving electrolyte impregnated in the capacitor element, a bottomed metal case for housing the capacitor element impregnated with the driving electrolyte, and an opening of the metal case is sealed The driving electrolyte solution comprises an electrolyte composed of a carboxylic acid and / or an inorganic acid, and a mixed solvent of an organic solvent and water, and has a pH in the range of 6.0 to 8.5. The separator is made of a cellulosic fiber, and the cellulosic fiber is an aluminum electrolytic capacitor to which a heat-treated paper strength enhancer is bonded.

  According to the aluminum electrolytic capacitor of the present invention, by using the driving electrolyte as a mixed solvent of an organic solvent and water and an electrolyte, impedance can be reduced, and the electrolyte is a carboxylic acid and / or an inorganic acid. By adjusting the pH of the driving electrolyte to 6.0 to 8.5, the pH of the electrolyte is stabilized in a neutral region under a high temperature environment, and the dissolution reaction of aluminum used in the anode foil and the cathode foil is suppressed. As a result, a long life can be realized as an aluminum electrolytic capacitor.

  In addition, by combining a paper strength enhancer with a cellulose fiber as a separator by heat treatment, it can be made a paper strength enhancer that is insoluble in the water of the driving electrolyte solution. The loosening can be prevented, and as a result, a long life as an aluminum electrolytic capacitor can be realized.

  Hereinafter, an embodiment of an aluminum electrolytic capacitor according to the present invention will be described. FIG. 1 is a partially cutaway perspective view showing the structure of an aluminum electrolytic capacitor according to the present invention. In FIG. 1, 11 is an anode foil, 12 is a cathode foil, 13 is a separator, and the anode foil 11 has a dielectric oxide film formed by chemical conversion treatment on the surface of an aluminum foil whose effective surface area is enlarged by etching treatment. The effective surface area of the cathode foil 12 is increased by etching the aluminum foil. A capacitor element 19 is formed by winding the anode foil 11 and the cathode foil 12 through a separator 13, and an anode lead 15 and a cathode lead 16 are connected to the anode foil 11 and the cathode foil 12, respectively. An aluminum electrolytic capacitor is configured by impregnating the liquid 14 and inserting it into a metal case 18 made of aluminum and sealing with a sealing body 17 such as rubber.

  The separator 13 is made of a cellulosic fiber bonded with a paper strength enhancer by heat treatment. Moreover, what combined the paper strength enhancer and the silane coupling agent by the heat processing to cellulose fiber can also be used. These cellulosic fibers include at least one of rayon, manila hemp, craft, hemp, and esparto. These fibers have a fine apparent fiber spacing and have many fine through holes. Without lowering the conductivity of the electrolytic solution 14, it is possible to reduce the resistance loss of the aluminum electrolytic capacitor and increase the short-circuit failure rate.

  When a paper strength enhancer is bonded to the cellulose fiber by heat treatment, particularly when a polyacrylamide resin is used as the paper strength enhancer, the polyacrylamide resin is changed to polyacrylimide by the heat treatment, and the driving electrolyte 14 The separator 13 can be further prevented from swelling and loosening. Further, the condensation reaction occurs by heat treatment of the silane coupling agent, and the cellulose fiber is firmly bonded, so that the separator 13 can be prevented from swelling and loosening due to water.

  In order to bond the paper strength enhancer and the silane coupling agent to the cellulose fiber by heat treatment, the cellulose fiber provided with the paper strength enhancer is heat treated once, and then the silane coupling agent is adhered and dried, and then again. Bond by performing a heat treatment. Alternatively, a silane coupling agent may be attached to a cellulose fiber to which a paper strength enhancer has been applied and dried, followed by heat treatment for bonding. Furthermore, the capacitor element 19 may be formed by interposing a silane coupling agent between the anode foil 11 and the cathode foil 12 and dried, and then heat treatment may be performed.

  The temperature of the heat treatment is preferably in the range of 150 to 300 ° C., and the product life can be increased without impairing the function of the paper strength enhancer. In addition, if the temperature of heat processing is less than 150 degreeC, a paper strength enhancer cannot be made insoluble with respect to the water of the electrolyte solution 14 for a drive. On the other hand, when the heat treatment temperature exceeds 300 ° C., the separator 13 is carbonized and the fibers are burnt and thinned, the tensile strength and density of the separator 13 are lowered, and the short-circuit defect rate and voltage resistance are lowered.

  The paper strength enhancer is composed of at least one selected from vegetable gums, starches, semi-synthetic polymers, and synthetic polymers. In particular, the polyacrylamide resin, which is a synthetic polymer, is subjected to heat treatment to polyacrylimide. This is preferable because it is more insoluble in the driving electrolyte solution 14 and the separator 13 can be further prevented from swelling and loosening.

  Examples of the silane coupling agent include aminosilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltri And methoxysilane.

The separator 13 has a basis weight of 10 to 60 g / m ² . Since the separator 13 in the aluminum electrolytic capacitor obtained by using the separator 13 in this range can reduce the resistance, the ESR characteristic and the impedance can be reduced. The basis weight is a value in which the area of the separator 13 is expressed in grams (g) per 1 square meter (m ² ).

If the basis weight of the separator 13 is less than 10 g / m ² , the short-circuit failure rate cannot be improved. If the basis weight exceeds 60 g / m ² , the short-circuit failure rate is improved, but other capacitor characteristics. Cannot be improved. In addition, the more optimal basis weight range is 10-40 g / m < ² >.

  The driving electrolyte solution 14 is a mixed solvent of an organic solvent and water containing carboxylic acid and / or inorganic acid as an electrolyte, and the pH of the driving electrolyte solution is in the range of 6.0 to 8.5. .

  Examples of the organic solvent include alcohol solvents (ethylene glycol, propylene glycol, 1,4-butanediol, glycerin, polyoxyalkylene polyol, etc.), amide solvents (N-methylformamide, N, N-dimethylformamide, N-methylacetamide). N-methylpyrrolidinone, etc.), alcohol solvents (methanol, ethanol, etc.), ether solvents (methylal, 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, etc.), Nitrile solvents (acetonitrile, 3-methoxypropionitrile, etc.), furan solvents (2,5-dimethoxytetrahydrofuran, etc.), sulfolane solvents (sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, etc.), lactone solvents (γ- Butyrolactone, γ- Valerolactone, δ-valerolactone, 3-methyl-1,3-oxaziridin-2-one, 3-ethyl-1,3-oxazolidine-2-one, etc.), imidazolidinone solvent (1,3-dimethyl-2) -Imidazolidinone, etc.), pyrrolidone solvents alone or in combination of two or more. Among these, it is desirable to use ethylene glycol and γ-butyrolactone. Moreover, what contains 20 to 90 weight% of the electrolyte solution 14 for a drive from a viewpoint of an impedance is suitable for content of water.

  The electrolyte carboxylic acid is formic acid, acetic acid, lactic acid, glycolic acid, succinic acid, succinic acid, malonic acid, adipic acid, benzoic acid, salicylic acid, p-nitrobenzoic acid, glutaric acid, azelaic acid, ethylenediaminediacetic acid, ethylenediaminetetraacetic acid. It is one or more compounds selected from acetic acid, trimethyladipic acid, 1,6-decanedicarboxylic acid, 1,7-octanedicarboxylic acid, butaroctanedicarboxylic acid, and sebacic acid. By using these carboxylic acids, aluminum The repair effect of the oxide film is improved, and there is an effect that hydration deterioration can be suppressed. Furthermore, if an acid having a small molecular weight and a large acid are used in combination, it is possible to obtain an electrolytic solution excellent in both high electrical conductivity and high temperature stability.

  The inorganic acid is one or more compounds selected from phosphoric acid, phosphorous acid, hypophosphorous acid, boric acid, and sulfamic acid. By using the inorganic acid, both the properties of high electrical conductivity and high temperature stability are excellent. It has the effect of becoming an electrolytic solution.

  In either case of carboxylic acid or inorganic acid, ammonium can be used as the base component of the electrolyte.

  If necessary, various additives may be mixed in the driving electrolyte solution 14. Additives include phosphorus compounds [phosphoric acid, phosphate esters, etc.] boric acid compounds [boric acid, complex compounds of boric acid and polysaccharides (mannit, sorbit, etc.), boric acid and polyhydric alcohols (ethylene Glycol, glycerin, etc.)] and nitro compounds [o-nitrophenol, m-nitrophenol, p-nitrophenol, etc.]. Adding these additives may increase the spark voltage of the driving electrolyte 14 and may be preferable.

  In addition, by setting the pH of the driving electrolytic solution 14 to a range of 6.0 to 8.5, the pH of the electrolytic solution is stabilized in a neutral region under a high temperature environment and used for the anode foil 11 and the cathode foil 12. It is possible to suppress the dissolution reaction of aluminum.

  Here, when the pH exceeds 8.5, the dissolution reaction of aluminum proceeds due to alkali, and when the pH is less than 6.0, the dissolution reaction of aluminum proceeds due to an acid. In either case, the life of the aluminum electrolytic capacitor is shortened. Therefore, by setting the pH to 6.0 to 8.5, it is possible to suppress the dissolution reaction of aluminum particularly in a high temperature environment, and as a result, it is possible to realize a long-life aluminum electrolytic capacitor.

  The pH adjustment of the driving electrolyte solution 14 can be achieved by adding a basic compound. These basic compounds include hydroxyammonium, dihydroxyammonium, methylamine, ethylamine, ethanolamine, hydroxymethylaminomethane, dihydroxymethylaminomethane, trishydroxymethylaminomethane, trishydroxyethylaminomethane, dimethylamine, diethylamine, diethanolamine, trimethylamine. , Triethylamine, triethanolamine, tetramethylammonium, 1,2,3,4-tetramethylimidazolinium, and 1-methylpyridinium. Thereby, since the basic compound is more thermally stable than ammonia, there is less transpiration at a high temperature, and there is an effect that the pH of the driving electrolyte solution 14 can be suppressed from being acidic. Further, the amount to be added can be adjusted within a range corresponding to a pH of 6.0 to 8.5 at 30 ° C. according to the hydrogen ion concentration contained in the driving electrolyte solution 14.

  Hereinafter, specific examples of the present embodiment will be described.

(Example 1)
An anode foil made of an aluminum foil having a dielectric oxide film (chemical conversion voltage 10 V) formed by roughening the surface by etching and then anodizing, and a cathode foil obtained by etching the aluminum foil are wound with a separator interposed therebetween. A capacitor element was produced by turning.

The separator is made by impregnating cellulose fiber having a thickness of 40 μm and a basis weight of 20 g / m ² made of paper composed of rayon and hemp with a polyacrylamide resin diluted solution, and removing excess polyacrylamide resin with a press roll, followed by drying. After that, heat-treated at 150 ° C. for 5 minutes was used.

  The obtained capacitor element was impregnated with the driving electrolyte (A) shown in (Table 1) under reduced pressure conditions (-700 mmHg).

  Next, the capacitor element was inserted into a bottomed cylindrical aluminum case together with a sealing body made of resin vulcanized butyl rubber, the opening of the aluminum case was sealed by curling treatment, and finally a DC voltage of 6.3 V was applied to the ambient temperature. Aging was carried out by continuously applying at 105 ° C. for 1 hour to produce an aluminum electrolytic capacitor having a diameter of 10 mm and a height of 10 mm. The sealing body made of butyl rubber was composed of 30 parts of butyl rubber polymer, 20 parts of carbon, and 50 parts of an inorganic filler, and had a sealing body hardness of 70 IRHD (international rubber hardness unit).

(Example 2)
In Example 1, an aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolytic solution (B) shown in Table 1 was used instead of the driving electrolytic solution (A).

(Example 3)
In Example 1, an aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolytic solution (C) shown in Table 1 was used instead of the driving electrolytic solution (A).

Example 4
In Example 1, an aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolytic solution (D) shown in Table 1 was used instead of the driving electrolytic solution (A).

(Example 5)
In Example 1, an aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolytic solution (E) in (Table 1) was used instead of the driving electrolytic solution (A).

(Example 6)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the heat treatment temperature for bonding the polyacrylamide resin to the cellulosic fiber was performed at 200 ° C. for 5 minutes.

(Example 7)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the heat treatment temperature for bonding the polyacrylamide resin to the cellulosic fiber was 300 ° C. for 5 minutes.

(Example 8)
In Example 1, the cellulose fiber was impregnated with a diluted polyacrylamide resin solution, the excess polyacrylamide resin was removed with a press roll, and after drying, the separator fiber was subjected to vinyltriacetoxysilane (Toray Dow) as a silane coupling agent. Corning Co., Ltd. SZ6300) was applied, and after drying, heat treatment was performed at 150 ° C. for 5 minutes. Otherwise, an aluminum electrolytic capacitor was produced in the same manner as in Example 1.

Example 9
In Example 8, an aluminum electrolytic capacitor was produced in the same manner as in Example 8 except that the heat treatment temperature was 300 ° C. for 5 minutes.

(Example 10)
In Example 1, cellulosic fibers were impregnated with a diluted polyacrylamide resin solution, excess polyacrylamide resin was removed with a press roll, and after drying, heat treatment was performed at 150 ° C. for 5 minutes. Next, vinyl triacetoxysilane (SZ6300 manufactured by Toray Dow Corning Co., Ltd.) was applied to the separator fiber as a silane coupling agent, and was heat-treated at 150 ° C. for 5 minutes after drying. Otherwise, an aluminum electrolytic capacitor was produced in the same manner as in Example 1.

(Example 11)
In Example 10, an aluminum electrolytic capacitor was produced in the same manner as in Example 10 except that the heat treatment temperature was 300 ° C. for 5 minutes.

(Example 12)
An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that cellulose fibers were made of paper composed of Manila hemp and hemp. The thickness of the separator substrate was 40 μm, and the basis weight was 10 g / m ² .

(Example 13)
In Example 1, aluminum was used in the same manner as in Example 1 except that the double-layered paper composed of paper composed of kraft and espal and paper composed of manila hemp and hemp was used. An electrolytic capacitor was produced. The thickness of the double paper was 70 μm and the basis weight was 60 g / m ² .

(Example 14)
In Example 1, a cellulose fiber having a thickness of 40 μm and a basis weight of 20 g / m ² made of paper composed of rayon and hemp as a separator was impregnated with a polyacrylamide resin diluted solution, and an excess polyacrylamide resin was pressed with a press roll. The capacitor element is formed by interposing the separator substrate dried by applying a silane coupling agent between the anode foil and the cathode foil, and then heat-treating the capacitor element at 150 ° C. An aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the above-described one was used.

(Comparative Example 1)
In Example 1, a driving electrolyte solution without adding a pH-adjusting hydroxyammonium was used, and the separator was made of paper composed of rayon and hemp and had a thickness of 40 μm and a basis weight of 20 g / m ² . Aluminum electrolytic capacitor in the same manner as in Example 1 except that a cellulose base fiber was impregnated with a diluted polyacrylamide resin solution, excess polyacrylamide resin was removed with a press roll, and a dried (100 ° C.) separator substrate was used. Was made. The paper thickness was 40 μm and the basis weight was 20 g / m ² .

(Comparative Example 2)
In Example 1, except that a paper composed of rayon and hemp was impregnated with a diluted polyacrylamide resin as a separator, excess polyacrylamide resin was removed with a press roll, and dried (100 ° C.). An aluminum electrolytic capacitor was produced in the same manner as in Example 1. The paper thickness was 40 μm and the basis weight was 20 g / m ² .

(Comparative Example 3)
In Example 1, an aluminum electrolytic capacitor was produced in the same manner as in Example 1 except that the driving electrolytic solution (F) shown in Table 1 was used instead of the driving electrolytic solution (A).

  (Table 2) shows the results of producing 20 aluminum electrolytic capacitors of Examples 1 to 14 and Comparative Examples 1 to 3 and conducting a life test. The load test was conducted at a temperature of 105 ° C. for the life test. The ESR characteristic is a measurement result at 100 kHz.

  As apparent from (Table 2), the aluminum electrolytic capacitors of Examples 1 to 14 to which the present invention was applied were obtained by adding a paper strength enhancer of polyacrylamide resin or a paper strength enhancer and a silane coupling agent to cellulosic fibers. Since the heat treatment is performed after the formation, the polyacrylamide resin, which is a paper strength enhancer, is changed to an imide, and further, for those formed with a silane coupling agent, a condensation reaction occurs due to the heat treatment of the silane coupling agent, Since it strongly binds to cellulosic fibers, it can be used as a paper strength enhancer that is insoluble in the water of the driving electrolyte, and can prevent swelling and loosening between separator fibers. In the electrolytic capacitor using the driving electrolyte solution, it is possible to achieve long life and high reliability.

  In addition, the aluminum electrolytic capacitor of Example 5 is a comparison of the presence or absence of moisture in the driving electrolyte compared to Comparative Example 3, but there is a difference in the characteristic values that are apparent in the 105 ° C. load test. As can be seen, the present invention is exhibited by containing moisture in the driving electrolyte.

  As described above, the aluminum electrolytic capacitor according to the present invention further prevents the separator from swelling and loosening even when a driving electrolytic solution composed of an organic solvent and water is used, so that the separator becomes more insoluble in the driving electrolytic solution. Therefore, it is useful as an electrolytic capacitor having excellent impedance characteristics, long life and high reliability.

The partially cutaway perspective view of the aluminum electrolytic capacitor in one embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Anode foil 12 Cathode foil 13 Separator 14 Driving electrolyte 15 Anode lead 16 Cathode lead 17 Sealing body 18 Metal case 19 Capacitor element

Claims (7)

A capacitor element in which an anode foil in which an anode lead is connected to an aluminum foil having a dielectric oxide film formed on the surface and a cathode foil in which a cathode lead is connected to the aluminum foil are wound with a separator interposed therebetween, and to this capacitor element A driving electrolyte solution impregnated; a bottomed metal case that houses a capacitor element impregnated with the driving electrolyte solution; and a sealing body that seals an opening of the metal case, the driving electrolyte solution. Is composed of an electrolyte composed of a carboxylic acid and / or an inorganic acid, a mixed solvent of an organic solvent and water, and has a pH in the range of 6.0 to 8.5, and the separator is composed of cellulosic fibers. Cellulose fibers are aluminum electrolytic capacitors that are bonded with heat-treated paper strength enhancers. 2. The aluminum electrolytic capacitor according to claim 1, wherein the driving electrolyte uses ammonium as a base component of the electrolyte and further adds a base component other than ammonium. The aluminum electrolytic capacitor according to claim 1, wherein the amount of water in the driving electrolyte is 20% to 90%. The aluminum electrolytic capacitor according to claim 1, wherein the cellulosic fiber contains at least one of rayon, Manila hemp, craft, hemp, and esparto. 2. The aluminum electrolytic capacitor according to claim 1, wherein the paper strength enhancer is formed by changing the polyacrylamide resin to polyacrylimide by heat treatment and bonding it to the separator fiber. The aluminum electrolytic capacitor according to claim 1, wherein the separator is obtained by bonding a paper strength enhancer and a silane coupling agent to cellulose fibers by heat treatment. The basis weight of the separator, aluminum electrolytic capacitor according to any one of claims 1 to 6 in the range of 10 to 60 g / m ^2.

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