Use of an Electrolyte for Driving Electrolytic Capacitor and Electrolytic Capacitor
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(19) TZZ_Z¥_T (11) EP 1 760 737 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) Int Cl.: of the grant of the patent: H01G 9/035 (2006.01) H01G 9/10 (2006.01) 31.10.2018 Bulletin 2018/44 H01G 9/145 (2006.01) H01G 11/52 (2013.01) H01G 11/58 (2013.01) (21) Application number: 04773564.2 (86) International application number: (22) Date of filing: 27.09.2004 PCT/JP2004/014535 (87) International publication number: WO 2005/101433 (27.10.2005 Gazette 2005/43) (54) USE OF AN ELECTROLYTE FOR DRIVING ELECTROLYTIC CAPACITOR AND ELECTROLYTIC CAPACITOR VERWENDUNG EINES ELEKTROLYTEN FÜR EINEN ANSTEUER-ELEKTROLYTKONDENSATOR UND ELEKTROLYTKONDENSATOR UTILISATION D’UN ÉLECTROLYTE POUR UN CONDENSATEUR ÉLECTROLYTIQUE ATTAQUANT ET CONDENSATEUR ÉLECTROLYTIQUE (84) Designated Contracting States: (56) References cited: DE EP-A- 1 006 536 EP-A- 1 063 662 EP-A- 1 460 660 DE-U1- 20 204 027 (30) Priority: 13.04.2004 JP 2004118009 JP-A- 1 235 226 JP-A- 62 018 704 JP-A- 2000 150 322 JP-A- 2000 173 876 (43) Date of publication of application: JP-A- 2002 184 655 JP-A- 2002 289 482 07.03.2007 Bulletin 2007/10 JP-A- 2003 068 581 JP-A- 2003 100 558 JP-A- 2004 014 666 JP-A- 2004 031 983 (73) Proprietor: Rubycon Corporation US-A- 5 001 265 US-A- 6 063 967 Ina-shi, US-A1- 2002 016 073 Nagano-ken 399-4593 (JP) • DATABASE WPI Week 200204 Thomson (72) Inventors: Scientific, London, GB; AN 2002-030521 • Uzawa, Shigeru XP002545864 & JP 2001 291643 A (RUBICON KK) Ina-shi, Nagano 3994593 (JP) 19 October 2001 (2001-10-19) • Komatsu, Akihiko • DATABASE WPI Week 200377 Thomson Ina-shi, Nagano 3994593 (JP) Scientific, London, GB; AN 2003-817612 • Ogawara, Tetsushi XP002545865 & JP 2003 109855 A (NIPPON Ina-shi, Nagano 3994593 (JP) CHEMICON CORP) 11 April 2003 (2003-04-11) • Sakurai, Yoshishige Ina-shi, Nagano 3994593 (JP) (74) Representative: Cohausz & Florack Patent- & Rechtsanwälte Partnerschaftsgesellschaft mbB Bleichstraße 14 40211 Düsseldorf (DE) Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 760 737 B1 Printed by Jouve, 75001 PARIS (FR) EP 1 760 737 B1 Description TECHNICAL FIELD 5 [0001] The present invention according to independent claims 1 and 12 relates to the use of an electrolytic solution in an electrolytic capacitor, and to an electrolytic capacitor using the same. More particularly, the present invention relates to the use of an electrolytic solution, in an electrolytic capacitor, which has very low equivalent series resistance and shows an excellent temperature stability that has never been attained, and also shows excellent electrical charac- teristics under low temperature conditions and stable electrical characteristics at a temperature just above the freezing 10 temperature, and to a high-performance electrolytic capacitor using the same. The electrolytic solution is useful in an aluminum electrolytic capacitor and in other electrolytic capacitors. BACKGROUND ART 15 [0002] Generally, a capacitor is a general electric part and has widely been used in power circuits and noise filters for digital circuits in various electric and electronic devices. Various electrolytic capacitors have been used and examples include an aluminum electrolytic capacitor, a wet tantalum electrolytic capacitor and the like. An aluminum electrolytic capacitor is expected to provide a particularly excellent function using the present invention. Therefore, the present invention will now be described with reference to this kind of electrolytic capacitor. 20 [0003] A conventional aluminum electrolytic capacitor can be produced by using an anode foil which is made by etching a high-purity aluminum foil, to increase its surface area, and anodizing the surface of the aluminum foil to provide a film, and a cathode foil whose surface has only been etched. The resulting anode foil and cathode foil are disposed opposite to each other and an element with a wound structure is made by interposing a separator (release paper) between the foils, followed by winding, and then an element made by winding the element with a wound structure is impregnated 25 with an electrolyte solution. The element impregnated with the electrolyte solution is contained in a case (generally made of aluminum), which is then sealed with an elastic sealant, thus completing an electrolytic capacitor. An electrolytic capacitor may have a structure other than a wound structure. [0004] In the above-described electrolytic capacitor, the characteristics of the electrolyte solution may be factors which decides the performances of the electrolytic capacitor. A conventional electrolyte solution for use in an electrolytic 30 capacitor is generally prepared by dissolving, as an electrolyte, a carboxylic acid such as adipic acid, benzoic acid, etc. or an ammonium salt thereof into a solvent prepared by adding about 30% by weight or less of water to ethylene glycol (EG) as a principal solvent. Such an electrolyte solution has a specific resistance of about 1.0 Ω·m (100 Ω·cm). Such a specific resistance is insufficient for recent small, high-performance electrolytic capacitors. Thus, a highly conductive electrolytic capacitor having a low specific resistance is required. 35 [0005] Intensive studies have been made in this field to improve the characteristics of the electrolytic solution, and various electrolytic solutions for use in an electrolytic capacitor have already been proposed. Referring to the patent documents which have recently been laid open to public inspection, there have been proposed the following aluminum electrolytic solutions for use in an electrolytic capacitor. [0006] An aluminum electrolytic solution for use in an electrolytic capacitor, which contains 20 to 90% by weight of 40 water, comprising at least one ammonium salt compound selected from the group consisting of ammonium salt com- pounds such as ammonium formate, as a principal electrolyte, and 1% by weight or more of at least one carboxylic acid compound selected from the group consisting of carboxylic acid compounds such as trimethyladipic acid which has no fire point, wherein a solidification point is -10°C or lower (see, Japanese Unexamined Patent Publication (Kokai) No. 2000-188240). 45 [0007] An aluminum electrolytic solution for use in an electrolytic capacitor, comprising a solvent containing 35 to 100%by weight of water and achelating agent (see,Japanese Unexamined Patent Publication(Kokai) No.2000-331886). [0008] An aluminum electrolytic solution for use in an electrolytic capacitor, comprising a solvent containing 35 to 100% by weight of water and a bonded product formed by bonding phosphoric acid ions to a water-soluble complex comprising aminopolycarboxylic acid and ammonium (see, Japanese Unexamined Patent Publication (Kokai) No. 50 2001-319833). [0009] Aluminum electrolytic solution for use in an electrolytic capacitor, comprising a solvent containing 35 to 100% by weight of water, at least one of adipic acid and a salt thereof dissolved in the solvent, and a bonded product formed by bonding phosphoric acid ions to a water-soluble complex comprising tannin and/or a decomposition product of tannin and aluminum (see, Japanese Unexamined Patent Publication (Kokai) No. 2002-83743). 55 [0010] An aluminum electrolytic solution for use in an electrolytic capacitor, comprising a solvent containing 35 to 100% by weight of water and a water-soluble aluminum complex bonded with phosphoric acid ions (see, International Publication No. WO00/55876). [0011] It can be seen that these electrolytic solutions for use in an electrolytic capacitor and other electrolytic solutions 2 EP 1 760 737 B1 have improved working life or durability at high temperature and other characteristics. However, some room for improve- ment is left. For example, a conventional electrolytic solution is inferior in noise removing abilityand in charging/dis- charging efficiency because the equivalent series resistance (ESR) of a capacitor cannot be decreased sufficiently. Therefore, the resulting electrolytic capacitor cannot be used advantageously as an electronic part. Also an electrolytic 5 capacitor using a conventional electrolytic solution has a problem that the electrical characteristics are unstable over a wide temperature range from a low temperature just above the freezing temperature to a high temperature and also the ESR drastically varies. Furthermore, a conventional electrolytic capacitor has a problem that swelling and liquid leakage from the case containing the capacitor element sometimes occurs and the working life at a high temperature is short. [0012] EP 1 006 536 A2 an electrolytic solution for use in an electrolytic capacitor, comprising a solvent made up of 10 80 to 20% by weight of water, at least one electrolyte selected from the group of carboxylic acids, their salts, inorganic acids, their salts, and a chelate compound. DISCLOSURE OF THE INVENTION 15 [0013] An object of the present invention is to solve the above problems of the prior art and to thereby decrease equivalent series resistance (ESR) of the capacitor, and thus provide a use of an electrolytic solution in an electrolytic capacitor which is excellent in noise removing ability and charging and discharging efficiency and is also capable of realizing an electrolytic capacitor having the ideal characteristics for electronic parts. [0014] More particularly, a first object of the present invention is to provide a use of an electrolytic solution which is 20 used in an electrolytic capacitor, capable of realizing an electrolytic capacitor which shows excellent and stable electrical characteristics in a wide temperature range from a low temperature just above the freezing temperature to high temper- ature and also causes little change in ESR.