JP4704366B2 - Electrolytic capacitor - Google Patents

Description

  The present invention relates to an electrolytic capacitor using a driving electrolyte as an electrolyte with a separator interposed between an anode foil and a cathode foil, and in particular, equivalent series resistance characteristics, short-circuit failure rate, high voltage resistance, and high heat resistance. Etc., and high reliability with high ripple and long life.

  In general, electrolytic capacitors, especially aluminum electrolytic capacitors, are formed by winding a separator between an anode aluminum foil and a cathode aluminum foil to form a capacitor element, and the capacitor element is immersed in a liquid driving electrolyte. Then, it is impregnated with a driving electrolyte as an electrolyte and sealed. As the driving electrolyte, ethylene glycol (EG), dimethylformamide (DMF) or γ-butyrolactone (GBL) is usually used as a solvent, and organic acid salts such as boric acid, ammonium adipate, and ammonium hydrogen maleate are used as these solvents. The melted material is used to penetrate from both ends of the capacitor element. Further, by using non-aqueous system of azelaic acid, butyloctanedioic acid, 5,6 decanedicarboxylic acid, dibasic acid having side chains and salts thereof as solutes, the water content in the driving electrolyte is reduced, and 100 ° C. Even in the above environment, the valve opening of the aluminum electrolytic capacitor due to an increase in the internal pressure of moisture can be suppressed.

  Since these conventional aluminum electrolytic capacitors are impregnated with a driving electrolyte in the separator, the impedance characteristics as a capacitor, in particular, the equivalent series resistance (hereinafter abbreviated as ESR) tends to be high, and therefore the impedance characteristics are improved. Cellulosic fibers such as rayon, kraft, manila hemp, hemp, esparto are used as the raw material for the separator in addition to means for reducing the resistance of the driving electrolyte or reducing the separator thickness or density. The thickness, density and tensile strength of the separator are appropriately selected. However, lowering the resistance value of the driving electrolyte causes corrosiveness to the aluminum foil. On the other hand, if the separator is made thinner or the density is lowered, 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 put on the market becomes high.

  Therefore, in order to reduce the short-circuit defect rate, the thickness of the separator is increased, the density is increased, and in the case of the same density, CSF (Canadian Standard Freeness) according to JIS P 8121 indicating the degree of beating of the raw material pulp. It is known that if the numerical value of) is reduced, 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. Further, it has been found that the effect of these items on ESR is that the ESR is linearly deteriorated when the separator is thickened, and that the ESR is deteriorated quadratically when the density is increased. 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 is changed from a normal wood kraft pulp to a softwood wood pulp, mana hemp pulp, esparto pulp, etc. Attempts have been made to produce thin, low density and dense separators by changing to smaller pulp.

  Patent Document 1 discloses an electrolysis that has a low density and a high tensile strength, and has improved short-circuit defect rate without adversely affecting impedance characteristics by using a new separator that does not shield inter-fiber voids. For the purpose of manufacturing capacitors, in electrolytic capacitors in which a separator is interposed between an anode foil and a cathode foil, the bond strength between fibers can be increased by impregnating and applying a purified solution of a paper strength enhancer to the separator after paper making. An increased electrolytic capacitor is disclosed.

  Patent Document 2 discloses an electrolysis in which the short-circuit defect rate is reduced in any of the element winding process, the impregnation process, the case insertion process, and the sealing rubber threading process even if a low-density thin separator is used to maintain good impedance characteristics. In order to obtain a capacitor, in an electrolytic capacitor in which a separator is interposed between an anode foil and a cathode foil, a wet paper strength enhancer using a weak acid such as citric acid or acetic acid is added to the separator as a pH stabilizer. An electrolytic capacitor made of cellulosic fibers is disclosed. As a wet paper strength enhancer, dialdehyde starch is used in which starch is oxidized with periodic acid and the constituent unit of starch is replaced with dialdehyde.

  Further, with the increase in the frequency of electronic equipment, there has been a demand for a large-capacity electrolytic capacitor having excellent impedance characteristics in a high-frequency region even in an electrolytic capacitor that is an electronic component. Recently, in order to reduce the impedance in this high frequency region, solid electrolytic capacitors using a solid electrolyte such as a conductive polymer with high electrical conductivity have been studied, and in response to the demand for large capacity. Using a conductive polymer of a winding type (with a structure in which an anode foil and a cathode foil are wound through a separator) that can easily increase the capacity in comparison with the case of laminating electrode foils Solid electrolytic capacitors have been commercialized.

  In order to avoid contact between the anode foil and the cathode foil, it is essential that a solid electrolytic capacitor adopting a winding type structure has a separator interposed therebetween. As this separator, an electrolytic solution using a conventional driving electrolyte is used as an electrolyte. Mainly used is a capacitor element wound with so-called electrolytic paper made of Manila hemp or kraft paper used for capacitors, and then carbonized with a heating method, etc., glass fiber nonwoven fabric, and resin by dry melt blow method. A non-woven fabric as a component is used.

  As a solid electrolytic capacitor, for example, Patent Document 3 discloses a structure in which an anode foil having a dielectric oxide film is wound around a separator paper and a cathode foil in order to reduce the size of the electrolytic capacitor and improve low impedance characteristics in a high frequency region. An electrolytic capacitor in which separator paper is made conductive by a conductive polymer is described. Polypyrrole, polyaniline, polythiophene or polyfuran is used as the conductive polymer.

Patent Document 4 discloses a porous resin film having an anode foil and a cathode foil having a dielectric oxide film between them for the purpose of providing an electrolytic capacitor having a low impedance in a high frequency range and excellent electrical characteristics. There is described an electrolytic capacitor that includes a capacitor element configured by winding with a conductive material, and a porous resin film in the capacitor element is made conductive by a conductive polymer.
Japanese Patent Laid-Open No. 08-273984 JP 63-051619 A Japanese Patent Laid-Open No. 01-090517 Japanese Patent Application Laid-Open No. 07-249543

  However, if a low-density separator is used to improve the ESR characteristics of the conventional aluminum electrolytic capacitor described above, the tensile strength of the separator is not sufficient, and the separator is cut to the required width when manufacturing the capacitor element. When doing so, there is a difficulty that paper breakage is likely to occur. Furthermore, there is a problem that the short circuit between the anode foil and the cathode foil or the withstand voltage characteristic deteriorates.

  In addition, when the separator is impregnated with a refined solution of a paper strength enhancer, the bond strength between the fibers increases, but only the paper strength enhancer adheres to the surface of the cellulosic fiber. When the liquid is impregnated and used for a long period of time, the separator gradually swells, and there is a problem in the reliability of the aluminum electrolytic capacitor.

  Furthermore, since a solid electrolyte such as a conductive polymer instead of the driving electrolyte uses only a solid electrolyte with poor repair properties such as a dielectric oxide film, the conventional driving electrolyte As compared with an aluminum electrolytic capacitor using aluminum, there is a problem that an increase in leakage current or a short circuit failure due to the occurrence of a defect in the dielectric oxide film is likely to occur, and an aluminum electrolytic capacitor having a high withstand voltage cannot be obtained.

  On the other hand, in the structure of a wound electrolytic capacitor, general cellulosic fibers are chemically unstable with respect to a processing solution such as an oxidant solution required for a polymerization reaction when forming a conductive polymer on a separator. Therefore, there is a problem that it is difficult to form a conductive polymer. In order to form the conductive polymer in the separator, it is preferable to use synthetic fibers such as polyester fiber, polyethylene fiber, and polypropylene fiber in order to improve ESR characteristics. However, the cost of the separator itself in the electrolytic capacitor is increased and the heat resistance is increased. There is also a problem.

  Therefore, the present invention eliminates the problems of the conventional aluminum electrolytic capacitor, improves the ESR characteristics, improves the short-circuit failure rate, high voltage resistance, and high heat resistance, and has high ripple and long life. An object of the present invention is to provide an electrolytic capacitor.

In order to achieve the above object, the present invention provides an electrolytic capacitor in which a capacitor element is formed by interposing a separator between an anode foil and a cathode foil, and the capacitor element is impregnated with a driving electrolyte solution. , dried by applying a silane coupling agent to cellulosic fibers with attached paper strength agent comprising a polyacrylamide resin, it was heat-treated at 200 to 300 [° C., polyacrylamide resin in the paper strength agent is a basic means Rutotomoni is imidized, the electrolytic capacitor is coupled to the silane coupling agent to the cellulosic fiber. The capacitor element was provided with a conductive polymer solid electrolyte.

In the electrolytic capacitor, the driving electrolyte is made of a mixed solvent of an organic solvent and water, and the amount of water in the driving electrolyte is in the range of 20 to 90% by weight.

According to the electrolytic capacitor of the present invention, a cellulose fiber with a paper strength enhancer made of polyacrylamide resin attached as a separator is dried by applying a silane coupling agent and then heat treated at 200 to 300 ° C. By using, the amide group of the polyacrylamide resin, which is a paper strength enhancer, is changed to imide, and the paper strength enhancer can be made insoluble in the water of the driving electrolyte. Further, when the silane coupling agent is heat-treated, a condensation reaction with cellulose occurs and the cellulose-based fibers are firmly bonded to each other, so that swelling and loosening between the fibers due to water in the separator can be prevented. Furthermore, since it has a silanol group bonded to a hydroxyl group of cellulose on the cellulose surface, ESR does not increase even when a driving electrolyte is used. As a result, it is possible to achieve high reliability with a long life of the electrolytic capacitor using the driving electrolytic solution composed of an organic solvent and water.

  In addition, since the separator is chemically stabilized by heat treatment of a paper strength enhancer and a silane coupling agent, a conductive polymer is easily formed, and ESR characteristics, short-circuit failure rate, high pressure resistance, and high heat resistance , Electrolytic capacitors with excellent high ripple can be obtained.

  An aluminum electrolytic capacitor as the best first embodiment of the electrolytic capacitor according to the present invention will be described below. FIG. 1 is a cross-sectional perspective view of a main part showing the structure of an electrolytic capacitor in the present invention. In the figure, 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 cathode foil 12 is formed by etching an 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 manufactured by impregnating the liquid 14 and inserting it into a metal case 18 made of aluminum and sealing with a sealing material 17 such as rubber.

The separator 13 is made of paper that is heat-treated at 200 to 300 ° C. after a silane coupling agent is applied to a cellulose fiber to which a paper strength enhancer made of polyacrylamide resin is attached and dried . The polyacrylamide resin, which is a paper strength enhancer, is converted into an imide by heat treatment, and can be made into a paper strength enhancer that is insoluble in the water of the driving electrolyte. 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.

Here, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (KBE603, manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a silane coupling agent on a separator base material made of cellulose fiber to which a polyacrylamide resin is attached. Using separators 1, 2 and 3 in which the silane coupling agent was heat-treated at the coating amount, heat treatment temperature and heat treatment time shown in Table 1, the tensile strength of the separator was measured under the following test conditions. The results are shown in Table 2.
Test conditions: A separator having a width of 15 mm is immersed in pure water for 30 seconds, and then tested according to the tensile strength item of JIS C2111 (electrical insulating paper test method).

As apparent from Table 2, the separator 2 and the separator 3 treated with the silane coupling agent have a heat treatment temperature of 200 to 300 ° C. and a treatment time of 10 as compared with the separator 1 not treated with the silane coupling agent. Tensile strength of those treated for ˜30 minutes (but up to 10 minutes at 300 ° C.) increases. For example, when heat treatment is performed at 200 ° C. for 10 minutes, the tensile strength of the coating amount 0 g / m ² separator 1 is 2.1 N / 15 mm, whereas the coating amount 0.8 g / m ² separator 2 is 3 In the separator 3 with a coating amount of 1.8 g / m ^{2 to} 0.7 N / 15 mm, the tensile strength is actually improved to 4.6 N / 15 mm. As shown in Table 2, when the heat treatment temperature is 300 ° C., if the heat treatment time reaches 30 minutes, the tensile strength of the separator is lowered, so the heat treatment temperature needs to be kept at about 10 minutes. Also, when the heat treatment temperature is 250 ° C., if the heat treatment time reaches 30 minutes, the tensile strength decreases compared to the case where the heat treatment time is 10 minutes, so the heat treatment temperature and the heat treatment time should be selected within an appropriate range. Is preferred.

  This is because the amide group of the polyacrylamide resin, which is a paper strength enhancer, is changed to an imide and can be made into a paper strength enhancer that is insoluble in water. Furthermore, by heat treating the silane coupling agent, cellulose It is considered that the condensation reaction occurred and the cellulose fibers were firmly bonded to each other, and swelling and loosening between the fibers due to the water of the separator could be prevented.

In Table 1, the coating amount of the silane coupling agent was evaluated at two points of 0.8 g / m ² and 1.8 g / m ² , but when the coating amount exceeded 2.0 g / m ² , cellulosic fibers The gap between them is reduced and the ESR characteristic as an electrolytic capacitor is deteriorated, and if it is less than 0.5 g / m ² , the effect of the silane coupling agent cannot be exhibited. Therefore, the coating amount of the silane coupling agent ^is suitably from ^{0.5g / m 2 ~2.0g / m 2} , is preferably in the range of 0.8g ^{/ m 2} ~1.8g ^/ m 2 .

  The heat treatment of the silane coupling agent is performed by once treating the separator base material made of cellulosic fiber to which the polyacrylamide resin is adhered, and then applying the silane coupling agent and drying, or anode foil and cathode foil A separator made of cellulose fiber to which a polyacrylamide resin is attached may be subjected to heat treatment after forming a capacitor element 19 by interposing a dried cellulose fiber with a silane coupling agent interposed therebetween. What was heat-treated after applying a silane coupling agent to the substrate and drying it is attached to the cellulosic fiber in a state where the polyacrylamide resin and the silane coupling agent are entangled, and the cellulose surface and the silane coupling agent Is preferable because the reaction proceeds efficiently.

As the cellulosic fiber, a fiber containing at least one of rayon, Manila hemp, craft, hemp, and esparto is used. These fibers have a fine apparent fiber spacing and a large number of fine through-holes, so that the conductivity of the driving electrolyte 14 is not lowered, the resistance loss of the aluminum electrolytic capacitor is reduced, and the resistance is increased. The short defect rate can be increased. The separator 13 has a basis weight of 10 to 60 g / m ² . Since the resistance occupied by the separator 13 in the aluminum electrolytic capacitor obtained by using the separator in this range can be lowered, there is an effect on the ESR characteristic and the impedance reduction. The basis weight is a value in which the area of the separator 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 are improved. Cannot be measured. The optimum basis weight range is 10 to 40 g / m ² .

  As the silane coupling agent, vinyl type, epoxy type, and amino type can be used. Examples of vinyl type include vinyltrichlorosilane, vinyltrimethoxysilane, and vinyltriethoxysilane. Epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane and the like.

  In addition, the amino group includes γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, N 2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N- (Vinylbenzyl) -2-aminoethyl-3 Aminopropyltrimethoxysilane hydrochloride and the like.

  The driving electrolytic solution 14 is basically composed of a mixed solvent of an organic solvent and water and a solute containing at least one of an inorganic acid, an organic acid, an inorganic acid salt, and an organic acid salt, and particularly has an ESR characteristic of an electrolytic capacitor. Can be improved.

  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.), nitriles Solvent (acetonitrile, 3-methoxypropionitrile, etc.), furan solvent (2,5-dimethoxytetrahydrofuran, etc.), sulfolane solvent (sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, etc.), carbonate solvent (propylene carbonate) Ethylene carbonate, diethyl carbonate, styrene carbonate, dimethyl carbonate or methyl ethyl carbonate), lactone solvent (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 solvent 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 is suitable for content of water.

  The solute is composed of an inorganic acid, an organic acid, an inorganic acid salt, and a solute containing at least one organic acid salt. Among these, boric acid, phosphoric acid, azelaic acid, adipic acid, glutaric acid, phthalic acid, Examples thereof include dibasic acids such as maleic acid, benzoic acid, 5,6-decanedicarboxylic acid, 1,7-octanedicarboxylic acid, 1,6-decanedicarboxylic acid, and salts thereof. As the salt, ammonium salt, amine salt, quaternary ammonium salt, amidine salt and the like can be used.

  Hereinafter, specific examples and comparative examples of the first embodiment of the aluminum electrolytic capacitor according to the present invention will be described.

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 a separator base material (a thickness of 40 μm, basis weight 20 g / m ² ) made of paper made of rayon and hemp with a diluted polyacrylamide resin, and removing excess polyacrylamide resin with a press roll. The separator substrate was subjected to heat treatment at 200 ° C. for 5 minutes after drying.

Next, this separator base material B was coated with a coating amount of 1.0 g / L using N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (KBM603 manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent. A separator that was heat-treated at 200 ° C. for 30 minutes after being applied to m ² and dried was used as a separator. The obtained capacitor element was impregnated with the driving electrolyte A shown in Table 3 under reduced pressure (-700 mmHg). Next, after inserting the capacitor element into the bottomed cylindrical aluminum case together with the resin vulcanized butyl rubber sealing material, the opening of the aluminum case was sealed by curling treatment, and finally the DC voltage of 6.3 V was applied to the ambient temperature of 105 ° C. Aging was performed by continuously applying for 1 hour to produce an aluminum electrolytic capacitor having a diameter of 10 mm and a height of 10 mm. The butyl rubber sealing material was composed of 30 parts of butyl rubber polymer, 20 parts of carbon, and 50 parts of an inorganic filler, and a sealing material hardness of 70 IRHD (international rubber hardness unit) was used.

In Example 1, the separator substrate i was impregnated with a diluted polyacrylamide resin solution, and the excess polyacrylamide resin was removed with a press roll and dried to obtain a separator substrate C. Silane coupling was applied to the separator substrate c. Using N-2- (aminoethyl) -3-aminopropyltrimethoxysilane as an agent, the coating amount was 1.0 g / m ^2, and after drying, heat treatment was performed at 200 ° C. for 30 minutes. An aluminum electrolytic capacitor was manufactured through the same process as in Example 1 except that the separator was used as a separator.

  In Example 2, an aluminum electrolytic capacitor was manufactured through the same steps as Example 2 except that the heat treatment temperature of the silane coupling agent was 250 ° C. for 10 minutes.

  In Example 2, an aluminum electrolytic capacitor was manufactured through the same process as Example 2 except that the heat treatment temperature of the silane coupling agent was 300 ° C. for 5 minutes.

In Example 2, aluminum electrolysis was performed through the same steps as in Example 2 except that the separator substrate i was made of paper composed of Manila hemp and hemp (thickness 40 μm, basis weight 10 g / m ² ). A capacitor was produced.

In Example 2, a double paper (thickness 70 μm, basis weight 60 g / m ² ) made of paper made of kraft and espal as separator base material i and paper made of manila hemp and hemp was used. Except for the above, an aluminum electrolytic capacitor was manufactured through the same process as in Example 2.

  In Example 2, an aluminum electrolytic capacitor was manufactured through the same process as Example 2 except that the driving electrolyte B shown in Table 3 was used instead of the driving electrolyte A.

  In Example 2, an aluminum electrolytic capacitor was manufactured through the same process as Example 2 except that the driving electrolyte C in Table 3 was used instead of the driving electrolyte A.

  In Example 2, an aluminum electrolytic capacitor was fabricated through the same steps as Example 2 except that the driving electrolyte D in Table 3 was used instead of the driving electrolyte A.

  In Example 2, an aluminum electrolytic capacitor was manufactured through the same process as Example 2 except that the driving electrolyte E shown in Table 3 was used instead of the driving electrolyte A.

  In Example 1, a separator was used except that a separator was formed by interposing a separator obtained by applying a silane coupling agent to the separator substrate C in Example 2 and drying the separator, followed by heat treatment. The aluminum electrolytic capacitor was manufactured through the same process as in Example 1.

[Comparative Example 1]
As the separator, the same steps as in Example 1 were used except that the separator substrate in Example 1 was impregnated with the diluted polyacrylamide resin solution, the excess polyacrylamide resin was removed with a press roll, and the dried product was used. After that, an aluminum electrolytic capacitor was produced.

[Comparative Example 2]
In Example 1, an aluminum electrolytic capacitor was produced using the separator base material in Example 1 as a separator.

[Comparative Example 3]
As a separator, the separator substrate a in Example 1 was impregnated with a diluted polyacrylamide resin solution, and the excess polyacrylamide resin was removed by a press roll and dried. Further, N-2- (aminoethyl) was used as a silane coupling agent. Example 1 except that a separator obtained by applying and drying -3-aminopropyltrimethoxysilane (KBM603 manufactured by Shin-Etsu Chemical Co., Ltd.) so that the coating amount is 0.5 g / m ² is used. An aluminum electrolytic capacitor was fabricated through the same process.

  Table 3 shows component configurations of the driving electrolytes A to E used in Examples 1 to 11 and Comparative Examples 1 to 3.

  Table 4 shows the results obtained by fabricating 20 aluminum electrolytic capacitors of Examples 1 to 11 and Comparative Examples 1 to 3 and conducting a life test. The load test was conducted at a test temperature of 105 ° C. The ESR characteristic is a measurement result at 100 kHz.

  As is apparent from Table 4, the aluminum electrolytic capacitors of Examples 1 to 11 to which the present invention was applied formed a paper strength enhancer of polyacrylamide resin and a silane coupling agent on the separator as compared with Comparative Examples 1 to 3. Since the post-heat treatment is performed, the polyacrylamide resin, which is a paper strength enhancer, is converted into an imide, and further, a condensation reaction occurs due to the heat treatment of the silane coupling agent, and the cellulose fiber is firmly bonded. Since it can be a paper strength enhancer that is insoluble in water of the electrolytic solution and can prevent swelling and loosening between separator fibers, an electrolytic capacitor using a driving electrolytic solution composed of an organic solvent and water can be used. Long life and high reliability can be achieved with low ESR.

  Next, an aluminum electrolytic capacitor as a second preferred embodiment of the electrolytic capacitor according to the present invention will be described. In the first embodiment, the separator 13 is subjected to a heat treatment by applying a silane coupling agent to the cellulose fiber to which a paper strength enhancer made of polyacrylamide resin is attached, and imidizing the polyacrylamide resin of the paper strength enhancer. And using an aluminum electrolytic capacitor in the same manner as in the first embodiment, except that a cellulosic fiber and a silane coupling agent bonded to a paper and a conductive polymer added to the paper are used. Configured.

  Examples of the conductive polymer include polypyrrole, poly3,4-ethylenedioxythiophene, and polyaniline. These conductive polymers are formed on the separator 13 by chemical polymerization or gas phase polymerization, or are formed on the capacitor element by chemical polymerization.

  Specific examples and comparative examples of the second embodiment of the aluminum electrolytic capacitor according to the present invention will be described below.

First, a separator base material a having a thickness of 40 μm and a basis weight of 20 g / m ² is used as a separator. The separator base material is impregnated with a diluted polyacrylamide resin solution and pressed. Excess polyacrylamide resin was removed with a roll, and after drying, heat treatment was performed at 200 ° C. for 5 minutes to obtain a separator base material. Subsequently, vinyl triacetoxysilane (SZ6030 manufactured by Toray Dow Corning Co., Ltd.) was applied as a silane coupling agent to the separator substrate and dried so that the coating amount was 1.5 g / m ² . Heat treatment was performed at 200 ° C. for 30 minutes to obtain a separator base material D.

  This separator substrate d is pulled up after being immersed in an aqueous solution containing ammonium persulfate (concentration 3% by weight) and 1-naphthalenesulfonic acid (concentration 5% by weight) which is an organic acid compound, and then exposed to pyrrole vapor. Thus, polypyrrole, which becomes a conductive polymer, was formed on the surface by chemical oxidative polymerization using the oxidizing action of ammonium persulfate. The separator substrate coated with polypyrrole was washed with water and dried at 105 ° C. to produce a separator. Next, an anode foil made of an aluminum foil whose surface is roughened by an etching process and then a dielectric oxide film (formation voltage 10 V) is formed by an anodic oxidation process, and a cathode foil obtained by etching the aluminum foil are separated from the separator. Capacitor elements were produced by interposing and winding.

  This capacitor element was impregnated with a γ-butyrolactone solution containing 25% by weight of triethylamine phthalate under a reduced pressure of −700 mmHg. Next, after inserting the capacitor element into the bottomed cylindrical aluminum case together with the resin vulcanized butyl rubber sealing material, the opening of the aluminum case was sealed by curling treatment, and finally the DC voltage of 6.3 V was applied to the ambient temperature of 105 ° C. Aging was performed by continuously applying for 1 hour to produce an aluminum electrolytic capacitor having a diameter of 10 mm and a height of 10 mm. The butyl rubber sealing material used was composed of 30 parts of butyl rubber polymer, 20 parts of carbon, and 50 minutes of inorganic filler, and had a sealing material hardness of 70 IRHD (international rubber hardness unit).

In Example 12, the separator substrate i was impregnated with a diluted polyacrylamide resin solution, and the excess polyacrylamide resin was removed by a press roll and dried to obtain a separator substrate C, and silane coupling was performed on the separator substrate C. N-2- (aminoethyl) -3-aminopropyltrimethoxysilane was applied as an agent so that the coating amount was 1.0 g / m ^2, and after drying, heat-treated at 200 ° C. for 30 minutes An aluminum electrolytic capacitor was manufactured through the same process as Example 12 except that was used as a separator.

  In Example 13, an aluminum electrolytic capacitor was produced through the same process as Example 13 except that the heat treatment after the formation of the silane coupling agent was heat-treated at 250 ° C. for 10 minutes.

  In Example 13, an aluminum electrolytic capacitor was manufactured through the same process as Example 13 except that the heat treatment after the formation of the silane coupling agent was heat-treated at 300 ° C. for 5 minutes.

  In Example 12, the separator substrate i was impregnated with the diluted polyacrylamide resin solution, the excess polyacrylamide resin was removed with a press roll and dried, followed by applying vinyltriacetoxysilane as a silane coupling agent and drying. After that, an aluminum electrolytic capacitor was manufactured through the same process as Example 12 except that a separator that had been heat-treated at 250 ° C. for 10 minutes was used.

In Example 12, an aluminum electrolytic capacitor was subjected to the same steps as in Example 12 except that paper (thickness 40 μm, basis weight 10 g / m ² ) composed of Manila hemp and hemp was used instead of the separator base material A. Was made.

In Example 12, double paper (thickness 70 μm, basis weight 60 g / m ² ) composed of paper composed of craft and espal instead of separator base material a, and paper composed of manila hemp and hemp An aluminum electrolytic capacitor was fabricated through the same process as in Example 12 except that was used.

  In Example 12, the separator substrate i was impregnated with the diluted polyacrylamide resin solution, the excess polyacrylamide resin was removed with a press roll and dried, followed by applying vinyltriacetoxysilane as a silane coupling agent and drying. This was used as a separator base material, and this separator base material was interposed between the anode foil and the cathode foil to form a capacitor element, and then heat-treated at 250 ° C. for 10 minutes.

  Next, the capacitor element is dipped in an aqueous solution containing ammonium persulfate (concentration 3% by weight) and 1-naphthalenesulfonic acid (concentration 5% by weight) which is an organic acid compound, and then pulled up, and then exposed to pyrrole vapor. As a result, polypyrrole, which becomes a conductive polymer, was formed on the surface by chemical oxidative polymerization utilizing the oxidizing action of ammonium persulfate. An aluminum electrolytic capacitor was produced through the same process as in Example 12 except that the capacitor element coated with polypyrrole was washed with water and dried at 105 ° C. to produce a separator.

[Comparative Example 4]
In Example 12, a separator substrate (i) having a thickness of 40 μm and a basis weight of 20 g / m ² made of paper composed of rayon and hemp was impregnated with a polyacrylamide resin diluent, and excess polyacrylamide resin was removed with a press roll. Then, the vinyl triacetoxysilane was applied as a silane coupling agent and dried. Next, the separator substrate is pulled up after being immersed in an aqueous solution containing ammonium persulfate (concentration 3% by weight) and 1-naphthalenesulfonic acid (concentration 5% by weight), which is an organic acid compound, and then exposed to pyrrole vapor. As a result, polypyrrole, which becomes a conductive polymer, was formed on the surface by chemical oxidative polymerization utilizing the oxidizing action of ammonium persulfate. The separator base material coated with polypyrrole was washed with water and dried at 105 ° C., and an aluminum electrolytic capacitor was produced through the same process as in Example 12.

  Table 5 shows the results obtained by fabricating 20 aluminum electrolytic capacitors of Examples 12 to 19 and Comparative Example 4 and performing a life test. The load test was conducted at a test temperature of 105 ° C. The ESR characteristic is a measurement result at 100 kHz.

  As is apparent from Table 5, the aluminum electrolytic capacitors of Examples 12 to 19 to which the present invention was applied were obtained after forming a paper strength enhancer of polyacrylamide resin and a silane coupling agent on the separator as compared with Comparative Example 4. Since the heat treatment is performed, the polyacrylamide resin, which is a paper strength enhancer, is converted into an imide, and further, a condensation reaction occurs due to the heat treatment of the silane coupling agent, and it is strongly bonded to the cellulosic fiber. It is possible to suppress the deterioration of the separator due to the chemical oxidation polymerization. Therefore, the initial characteristics are dramatically improved even when compared with Comparative Example 4, and the product life is also improved because the separator is less deteriorated from the results of the life test and the strength of the separator itself is improved, ESR characteristics in a high frequency region can be enhanced.

As described above in detail, the separator used in the electrolytic capacitor according to the present invention is obtained by applying a silane coupling agent to a cellulose fiber to which a paper strength enhancer made of polyacrylamide resin is attached and drying it. Heat treatment at ~ 300 ° C changes the polyacrylamide resin, which is a paper strength enhancer, to imide with little deterioration, and further bonds with cellulosic fibers due to condensation reaction caused by heat treatment of the silane coupling agent, causing deterioration of the separator. Can be used as an electrolytic capacitor having excellent ESR characteristics, long life, and high reliability.

  In addition, by applying a conductive polymer to the separator, it has excellent ESR characteristics, short-circuit failure rate, high pressure resistance, high heat resistance, high ripple, and long life as an electronic component for vehicles and other high-frequency characteristics required. And can be used as a highly reliable electrolytic capacitor.

The principal part sectional perspective view showing the structure of an aluminum electrolytic capacitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Anode foil 12 ... Cathode foil 13 ... Separator 14 ... Electrolyte for drive 15 ... Anode lead 16 ... Cathode lead 17 ... Sealing material 18 ... Metal case 19 ... Capacitor element

Claims (4)

In an electrolytic capacitor in which a separator is interposed between an anode foil and a cathode foil to form a capacitor element, and the capacitor element is impregnated with a driving electrolyte,
The separator is formed by applying a silane coupling agent to a cellulose-based fiber to which a paper strength enhancer made of polyacrylamide resin is attached and drying it, followed by heat treatment at 200 to 300 ° C. Rutotomoni is imidized polyacrylamide resin, electrolytic capacitors, characterized in that to bind the silane coupling agent to the cellulosic fiber.   The electrolytic capacitor according to claim 1, wherein a conductive polymer solid electrolyte is provided in the capacitor element. Electrolytic capacitor according to claim 1 or 2 driving electrolyte is a mixed solvent of an organic solvent and water. The electrolytic capacitor according to claim 3 , wherein the amount of water in the driving electrolyte is 20 to 90% by weight.

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