JP5012377B2

JP5012377B2 - Electrolytic capacitor

Info

Publication number: JP5012377B2
Application number: JP2007256219A
Authority: JP
Inventors: 正郎坂倉; 賢次玉光
Original assignee: Nippon Chemi Con Corp
Current assignee: Nippon Chemi Con Corp
Priority date: 2007-09-28
Filing date: 2007-09-28
Publication date: 2012-08-29
Anticipated expiration: 2027-09-28
Also published as: JP2009088259A

Description

この発明は電解コンデンサ、特に高電圧における特性が安定で、高周波低インピーダンス特性を有する電解コンデンサに関する。 The present invention relates to an electrolytic capacitor, and more particularly to an electrolytic capacitor having stable characteristics at high voltage and high frequency and low impedance characteristics.

電解コンデンサは、アルミニウムまたはタンタルなどの表面に絶縁性の酸化皮膜が形成された弁金属を陽極電極箔に使用し、前記酸化皮膜層を誘電体とし、この酸化皮膜層の表面に電解質層となる電解液を接触させ、さらに通常陰極と称する集電用の電極箔を配置して構成されている。 An electrolytic capacitor uses a valve metal having an insulating oxide film formed on the surface of aluminum or tantalum as an anode electrode foil, and the oxide film layer is used as a dielectric, and an electrolyte layer is formed on the surface of the oxide film layer. An electrolyte solution is brought into contact with each other, and a current collecting electrode foil generally called a cathode is arranged.

このような電解コンデンサで高圧用に用いられるものでは、高電圧における特性の安定化を図るために、耐電圧が高く電極箔の劣化が少ない電解液として、エチレングリコールを溶媒とし、アゼライン酸、１，７−オクタンジカルボン酸またはそれらの塩を溶質とした電解液を用いることが一般的である。 In such an electrolytic capacitor used for high voltage, in order to stabilize the characteristics at high voltage, as an electrolytic solution having a high withstand voltage and little deterioration of the electrode foil, ethylene glycol is used as a solvent, azelaic acid, 1 , 7-octanedicarboxylic acid or an electrolyte solution thereof is generally used as a solute.

ところで、近年、電源の一次側には高調波対策のために力率改善回路が組み込まれるようになり、これに伴って、大きな高周波リップル電流に耐えられる高圧用の高周波低インピーダンス電解コンデンサが望まれている。 By the way, in recent years, a power factor correction circuit has been incorporated on the primary side of a power supply as a countermeasure against harmonics, and accordingly, a high-frequency high-frequency low-impedance electrolytic capacitor that can withstand a large high-frequency ripple current is desired. ing.

従来、電解コンデンサの低インピーダンス化の方法としては、電解液の比抵抗を下げることによって対応してきている。電解液の比抵抗を下げる方法としては、電解液中に水を多量に混合する方法が知られている。（特許文献１）
しかし、電解液中に水を多量に混合すると電解液の耐圧が低下するとともに、電極箔が水和されやすくなり、電解コンデンサの耐圧特性や信頼性が低下してしまう。 Conventionally, methods for reducing the impedance of electrolytic capacitors have been dealt with by reducing the specific resistance of the electrolytic solution. As a method for reducing the specific resistance of the electrolytic solution, a method of mixing a large amount of water in the electrolytic solution is known. (Patent Document 1)
However, when a large amount of water is mixed in the electrolytic solution, the pressure resistance of the electrolytic solution is lowered and the electrode foil is easily hydrated, so that the pressure resistance characteristics and reliability of the electrolytic capacitor are lowered.

このような、電解液の耐圧を改善する方法としては、電解液中にポリエチレングリコールを添加する方法が知られている。（特許文献２）
また、電極箔の水和劣化を緩慢にする方法としては、電極箔として非晶質酸化皮膜をもつ電極箔を用いる方法が知られている。（特許文献３） As a method for improving the pressure resistance of the electrolytic solution, a method of adding polyethylene glycol to the electrolytic solution is known. (Patent Document 2)
As a method for slowing the hydration deterioration of the electrode foil, a method using an electrode foil having an amorphous oxide film as the electrode foil is known. (Patent Document 3)

特開平１１−１４５００４号公報Japanese Patent Application Laid-Open No. 11-14504 特開昭６２−２６８１２１号公報JP 62-268121 A 特開２００５−１９７７３号公報JP-A-2005-19773

しかしながら、特許文献２では電解コンデンサの低インピーダンス化が困難であり、特許文献３では高圧化が不十分であり、従来では、高周波低インピーダンスで、耐電圧が高く、さらに信頼性の高い電解コンデンサは提案されていなかった。 However, in Patent Document 2, it is difficult to reduce the impedance of the electrolytic capacitor, and in Patent Document 3, the increase in voltage is insufficient. Conventionally, an electrolytic capacitor having high frequency, low impedance, high withstand voltage, and high reliability has been proposed. It was not proposed.

そこで、本発明は、高周波低インピーダンスで、耐電圧が高く、さらに信頼性も良好な電解コンデンサを提供することを目的とする。 Therefore, an object of the present invention is to provide an electrolytic capacitor having high frequency and low impedance, high withstand voltage, and good reliability.

本発明は、上記課題を解決するため、鋭意研究したものであり、リン酸化成皮膜を有する陰極箔は、そのリン酸吸着層が保護皮膜となり水和劣化を抑制することで、電解液への水の多量添加を可能とし、また、エチレングリコールを主成分とする溶媒に、アゼライン酸、１，７−オクタンジカルボン酸またはそれらの塩を溶解した高圧用電解液において、低比抵抗特性を有し、耐圧特性を改善し、電極箔の水和劣化を抑えることで電解コンデンサの寿命特性を良好に保つことを可能とする添加剤およびその添加量を明らかにすることでなされたものである。 The present invention has been intensively studied in order to solve the above-mentioned problems, and the cathode foil having a phosphorylation-forming film has a phosphoric acid adsorption layer serving as a protective film to suppress hydration deterioration. A large amount of water can be added, and it has a low specific resistance characteristic in an electrolyte for high pressure in which azelaic acid, 1,7-octanedicarboxylic acid or a salt thereof is dissolved in a solvent mainly composed of ethylene glycol. The present invention has been made by clarifying the additive and the amount of the additive that can improve the withstand voltage characteristics and suppress the hydration deterioration of the electrode foil to keep the life characteristics of the electrolytic capacitor favorable.

すなわち、本発明に係る電解コンデンサでは、陽極箔と陰極箔とをセパレータを介して巻回したコンデンサ素子に駆動用電解液を含浸したコンデンサ素子をアルミニウムケースに収納した電解コンデンサにおいて、駆動用電解液は、エチレングリコールを主溶媒とし、アゼライン酸、１，７−オクタンジカルボン酸またはそれらの塩を溶質とし、１５〜４０ｗｔ％の水と、１０〜３０ｗｔ％の高分子ポリマーと、リン酸化合物とを添加してなり、陰極箔は、リン酸化成皮膜を有する。 That is, in the electrolytic capacitor according to the present invention, in the electrolytic capacitor in which the capacitor element obtained by impregnating the driving electrolyte with the capacitor element in which the anode foil and the cathode foil are wound through the separator is housed in the aluminum case, the driving electrolyte They comprise ethylene glycol as a main solvent, azelaic acid, 1,7 and octane dicarboxylic acids or their salts and solutes, and 15 to 40 wt% of water, and 10 30 wt% of the high polymer, and a phosphoric acid compound In addition, the cathode foil has a phosphorylated film.

本発明において、高分子ポリマーは、ポリエチレングリコール、ポリオキシエチレングリコール、ポリプロピレングリコール、ポリビニールアルコールのいずれか１種以上であることが好ましい。 In the present invention, the polymer is preferably one or more of polyethylene glycol, polyoxyethylene glycol, polypropylene glycol, and polyvinyl alcohol.

本発明によれば、高圧用電解コンデンサにおいて、水和劣化しにくいリン酸化成皮膜を形成した陰極箔を使用すると共に、電解液中の水を一定量にコントロールすることで、低インピーダンス化と信頼性が両立できると共に、高分子ポリマーを一定量含有させることで耐電圧を向上し、リン酸化合物を添加することで陰極箔から電解液中へのリン酸の遊離が抑制され、電極箔の水和劣化がさらに抑制される電解液を用いることで、高周波低インピーダンスで、耐電圧が高く、さらに信頼性も良好な電解コンデンサを提供することができる。 According to the present invention, a high-voltage electrolytic capacitor uses a cathode foil on which a phosphating film that is not easily hydrated and deteriorated, and by controlling the amount of water in the electrolytic solution to a certain level, it is possible to reduce impedance and improve reliability. In addition to improving the withstand voltage by containing a certain amount of a high molecular weight polymer, the addition of a phosphoric acid compound suppresses the release of phosphoric acid from the cathode foil into the electrolyte, and the water in the electrode foil By using an electrolytic solution that further suppresses the deterioration of the sum, it is possible to provide an electrolytic capacitor with high frequency and low impedance, high withstand voltage, and good reliability.

本発明の電解コンデンサは、リン酸化成皮膜を有する陰極箔を用い、電解液としてエチレングリコールを主溶媒とし、アゼライン酸、１，７−オクタンジカルボン酸またはそれらの塩を溶質とし、１５〜４０ｗｔ％の水、１０〜３０ｗｔ％の高分子ポリマー、およびリン酸化合物を添加したものを用いている。 The electrolytic capacitor of the present invention uses a cathode foil having a phosphorylated film, contains ethylene glycol as a main solvent as an electrolytic solution, and contains azelaic acid, 1,7-octanedicarboxylic acid or a salt thereof as a solute, and is 15 to 40 wt%. Water, 10 to 30 wt% of a high molecular polymer, and a phosphate compound are used.

水の含有量は、１５〜４０ｗｔ％、好ましくは２０〜３０ｗｔ％であるが、この範囲未満では比抵抗低減効果が得られず、この範囲を越えると電極箔の水和劣化を抑制できなくなる。 The water content is 15 to 40 wt%, preferably 20 to 30 wt%. However, if it is less than this range, the effect of reducing the specific resistance cannot be obtained, and if it exceeds this range, hydration deterioration of the electrode foil cannot be suppressed.

高分子ポリマーの含有量は、１０〜３０ｗｔ％であるが、この範囲未満では耐電圧が低く、また、漏れ電流の増加が見られ、高圧品の製造が困難であり、この範囲を超えると電解液の比抵抗の上昇が激しいため、高周波低インピーダンスを満足できなくなる。 The content of the high molecular polymer is 10 to 30 wt%, but if it is less than this range, the withstand voltage is low, and an increase in leakage current is seen, making it difficult to produce a high-voltage product. Since the specific resistance of the liquid rises drastically, high frequency low impedance cannot be satisfied.

本発明の電解液に用いるアゼライン酸、１，７−オクタンジカルボン酸の塩としては、アンモニウム塩のほか、メチルアミン、エチルアミン、ｔ−ブチルアミン、ｎ−プロピルアミン等の一級アミン塩、ジメチルアミン、エチルメチルアミン、ジエチルアミン、ジ−ｎ−プロピルアミン、ジイソプロピルアミン等の二級アミン塩、トリ−ｎ−プロピルアミン、トリメチルアミン、トリエチルアミン、トリ−ｎ−ブチルアミン、ジメチルエチルアミン、等の三級アミン塩、ジエタノールアミン、トリエタノールアミン、ナフタレンジアミン、ベンジルアミン等の塩を例示することが出来る。 As salts of azelaic acid and 1,7-octanedicarboxylic acid used in the electrolytic solution of the present invention, ammonium salts, primary amine salts such as methylamine, ethylamine, t-butylamine and n-propylamine, dimethylamine, ethyl Secondary amine salts such as methylamine, diethylamine, di-n-propylamine, diisopropylamine, tertiary amine salts such as tri-n-propylamine, trimethylamine, triethylamine, tri-n-butylamine, dimethylethylamine, diethanolamine, Examples of the salt include triethanolamine, naphthalenediamine, and benzylamine.

また、リン酸化合物としては、正リン酸、亜リン酸、次亜リン酸、リン酸メチル、リン酸エチル、リン酸ジエチル、リン酸ブチル、リン酸ジブチル等を例示することが出来る。 Examples of the phosphoric acid compound include orthophosphoric acid, phosphorous acid, hypophosphorous acid, methyl phosphate, ethyl phosphate, diethyl phosphate, butyl phosphate, and dibutyl phosphate.

以下に実施例により本発明をさらに具体的に説明する。
（表１）に本発明の実施例、比較例について、電解コンデンサ用電解液の組成と、比抵抗および火花発生電圧を示した。ここで、火花発生電圧の測定には６２８Ｖｆｓ相当箔を使用しており、箔耐圧限界により測定不能であった電解液の火花発生電圧は６２８Ｖ以上と記載している。 The present invention will be described more specifically with reference to the following examples.
Table 1 shows the composition, specific resistance, and spark generation voltage of the electrolytic solution for electrolytic capacitors for the examples and comparative examples of the present invention. Here, a foil corresponding to 628 Vfs is used for the measurement of the spark generation voltage, and the spark generation voltage of the electrolyte, which cannot be measured due to the foil pressure limit, is described as 628 V or more.

次に、リン酸化成液中で３Ｖ化成皮膜を形成した陰極箔に、実施例１〜１０の電解液を組み合わせたもの、比較例１〜５の電解液を組み合わせたもの、および、アジピン酸化成液中で３Ｖ化成皮膜を形成した陰極箔に、比較例６の電解液（組成は実施例３と同じ）を組み合わせたものとで比較試験を行った。上記の２種の陰極箔（リン酸化成箔、および、アジピン酸化成箔）と陽極箔とを電解紙を介して巻回したコンデンサ素子に、（表１）に示す電解液を含浸して、４５０Ｖ−６．８μＦ（φ１０×２０ｍｍＬ）の電解コンデンサを作成し、初期特性測定後、１０５℃で定格電圧（４５０Ｖ）印加した状態での１０００時間後の特性を測定した。上記試験結果を（表２）に示す。 Next, a cathode foil in which a 3V chemical conversion film is formed in a phosphorylation liquid, a combination of the electrolytes of Examples 1 to 10, a combination of the electrolytes of Comparative Examples 1 to 5, and adipine oxidation A comparative test was conducted with a cathode foil in which a 3V chemical conversion film was formed in the liquid and the electrolyte solution of Comparative Example 6 (composition was the same as in Example 3). A capacitor element in which the above two types of cathode foils (phosphorylated and formed adipine oxidized foil) and an anode foil are wound through electrolytic paper is impregnated with the electrolytic solution shown in (Table 1), An electrolytic capacitor of 450V-6.8 μF (φ10 × 20 mmL) was prepared, and after initial characteristic measurement, characteristics after 1000 hours in a state where a rated voltage (450 V) was applied at 105 ° C. were measured. The test results are shown in (Table 2).

（表１）から分かるように、比較例１のような電解液中の水の添加量が１５ｗｔ％未満の場合や、比較例４のような高分子ポリマーの添加量が３０ｗｔ％を超えた場合には、実施例に比べて電解液の比抵抗上昇が著しく、これに伴って、（表２）に見られるように、製品化後のＥＳＲ特性が大きくなってしまっているのに対し、各実施例では、電解液比抵抗も、製品化後のＥＳＲ特性も低く抑えられている。 As can be seen from (Table 1), when the addition amount of water in the electrolytic solution as in Comparative Example 1 is less than 15 wt%, or when the addition amount of the polymer as in Comparative Example 4 exceeds 30 wt% In contrast, the increase in the specific resistance of the electrolytic solution compared to the example, and as shown in (Table 2), the ESR characteristics after commercialization have increased, In the examples, both the specific resistance of the electrolytic solution and the ESR characteristics after commercialization are kept low.

また、比較例３のような高分子ポリマーの添加が１０ｗｔ％未満の場合には、電解液耐圧が低下してしまい、また、実施例５のように、漏れ電流の増加が見られ、製品化が困難であるが、実施例の様に高分子ポリマーを１０ｗｔ％以上含有することで、水を多量に含んだ場合にも電解液耐圧を高く保つことが可能となり、高圧用電解コンデンサの製造が可能となる。 In addition, when the addition of the polymer as in Comparative Example 3 is less than 10 wt%, the electrolyte withstand voltage is lowered, and as in Example 5, an increase in leakage current is observed, and the product Although it is difficult to make a high-pressure electrolytic capacitor, it is possible to maintain a high electrolyte withstand voltage even when a large amount of water is contained by containing 10 wt% or more of a polymer as in the embodiment. Manufacture is possible.

更に、比較例２、５、６と実施例を比較すると、陰極箔にリン酸化成箔を用いるとともに、電解液にリン酸化合物を添加し、かつ、電解液中の水を４０ｗｔ％以下に抑えることではじめて、陰極箔の水和劣化が抑えられ、信頼性の良好な高圧用電解コンデンサが得られることが分かる。尚、１０５℃での定格電圧印加を２０００時間まで継続した場合、電解液中の水分添加量が２０〜３０ｗｔ％である、実施例２及び３の特性がより安定していた。 Further, when Comparative Examples 2, 5, and 6 are compared with Examples, a phosphorylated foil is used for the cathode foil, a phosphoric acid compound is added to the electrolytic solution, and water in the electrolytic solution is suppressed to 40 wt% or less. Thus, it can be seen that, for the first time, a hydration deterioration of the cathode foil is suppressed, and a high-voltage electrolytic capacitor with good reliability can be obtained. In addition, when the rated voltage application at 105 ° C. was continued up to 2000 hours, the characteristics of Examples 2 and 3 in which the amount of water added in the electrolytic solution was 20 to 30 wt% were more stable.

Claims

In an electrolytic capacitor in which a capacitor element in which a driving electrolyte is impregnated in a capacitor element in which an anode foil and a cathode foil are wound through a separator is housed in an aluminum case,
The driving electrolyte includes ethylene glycol as a main solvent, azelaic acid, 1,7-octanedicarboxylic acid or a salt thereof as a solute, 15 to 40 wt% water, 10 to 30 wt% polymer, Adding a phosphoric acid compound,
The electrolytic capacitor, wherein the cathode foil has a phosphorylated film.

2. The electrolytic capacitor according to claim 1, wherein the polymer is one or more of polyethylene glycol, polyoxyethylene glycol, polypropylene glycol, and polyvinyl alcohol.