JP2004186189A

JP2004186189A - Electrolyte for driving electrolytic capacitor

Info

Publication number: JP2004186189A
Application number: JP2002347931A
Authority: JP
Inventors: Akihiro Matsuda; 晃啓松田
Original assignee: Nichicon Corp
Current assignee: Nichicon Corp
Priority date: 2002-11-29
Filing date: 2002-11-29
Publication date: 2004-07-02

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte for driving an electrolytic capacitor which restrains an aluminum electrode foil from being hydrated at high temperature and is superior in reliability at high temperature when no load is applied. <P>SOLUTION: Carboxylic acid or its salt and phenylalanine represented by formula 1 are dissolved into a solvent containing polyvalent alcohol and water, whereby the electrode foil can be restrained from being hydrated at high temperature, and products can be improved in long term reliability even when the electrolyte is reduced in resistivity by mixing water into it. Phenylalanine is easily dissolved into a mixed solvent of polyvalent alcohol, such as ethylene glycol or the like, and water. Even if the electrolyte is increased in water content, the aluminum electrode foil can be restrained from being hydrated at high temperature. Therefore, the electrolytic capacitor can be improved in characteristics and reliability at high temperature. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術用分野】
本発明は、アルミニウム電解コンデンサの駆動用電解液（以下、電解液と称す）の改良に関するものである。
【０００２】
【従来の技術】
近年、電解コンデンサの小型化に伴い、アルミニウム電解コンデンサの陽極箔にはエッチング倍率の高いものが使用されるようになり、それに伴い、比抵抗の低い電解液が要求されている。このような電解液としては、従来、エチレングリコールを主溶媒とし、電解質としてカルボン基酸のアンモニウム塩を溶解したものが使用されている（例えば、特許文献１、２参照）。
【０００３】
【特許文献１】
特公平７−４８４６０号公報（第２頁、表）
【特許文献２】
特公平７−６３０４７号公報（第３頁、表１）
【０００４】
【発明が解決しようとする課題】
上記電解液で低比抵抗のものを得るには、電解質の濃度を高くするか、水を多量に添加しなければならない。しかし、電解質の濃度の増加は電解質の析出、耐電圧低下を起こすという問題がある。また、水を多量に添加した場合、電解コンデンサの高温無負荷時の漏れ電流を増加させるため、１０５℃での使用は困難であった。
【０００５】
本発明の課題は、上記の問題点を改善し、高温条件下においても使用可能な電解液を提供するものである。
【０００６】
【課題を解決するための手段】
上記課題を解決するため、本発明の電解コンデンサの駆動用電解液では、電解液にフェニルアラニンを溶解することで、高温下でのアルミニウム電極箔と水との水和反応を抑制して、高温無負荷での信頼性に優れた電解液を提供する。
【０００７】
すなわち、エチレングリコールなどの多価アルコールと水とを含む溶媒に、カルボン酸またはその塩と、以下の化学式で表わされるフェニルアラニンとを溶解したことを特徴とする。
【０００８】
【化２】

【０００９】
本発明に係る電解液では、フェニルアラニンを溶解したため、水の混合量が増加しても高温下での水と電極箔との水和反応を抑制できる。従って、水の添加で比抵抗を低くできるため、電解質の増量を必要としない。それ故、耐電圧を低下させることがないという効果も奏する。
【００１０】
本発明において、フェニルアラニンの溶解量が、電解液全体に対して０．１〜１．０ｗｔ％であることが好ましい。フェニルアラニンの添加量が０．１ｗｔ％未満では十分な効果が得られず、フェニルアラニンの添加量が１．０ｗｔ％を超えると比抵抗が高くなる傾向にある。
【００１１】
本発明において、水の混合量は電解液全体に対して２．０〜１０．０ｗｔ％であることが好ましい。２．０ｗｔ％未満では比抵抗がやや高く、１０．０ｗｔ％を超えると、フェニルアラニンによる水和反応を完全に防止しきれない傾向にある。
【００１２】
本発明において、上記カルボン酸としては、アゼライン酸、セバシン酸、１，６−デカンジカルボン酸、５，６−デカンジカルボン酸、７−ビニルヘキサデセン−１，１６−ジカルボン酸等を例示することができる。
【００１３】
また、カルボン酸の塩としては、アンモニウム塩の他、メチルアミン、エチルアミン、ｔ−ブチ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、ジエチルアミン等の二級アミン塩、トリメチルアミン、ジエチルメチルアミン、エチルジメチルアミン、トリエチルアミン等の三級アミン塩、テトラメチルアンモニウム、トリエチルメチルアンモニウム等の四級アンモニウム塩等を例示することができる。
【００１４】
【発明の実施の形態】
本発明では、エチレングリコールなどの多価アルコールおよび水を含む溶媒に、カルボン酸またはその塩と、フェニルアラニンとを溶解する。ここで、フェニルアラニンの溶解量は、電解液全体に対して０．１〜１．０ｗｔ％とする。また、水の混合量は、１．０〜１０．０ｗｔ％とする。
【００１５】
このような電解液では、電解液中のフェニルアラニンが電極箔表面に吸着するため、水の添加量が増加しても１０５℃の高温下での水と電極箔との水和反応を抑制でき、高温無負荷時の漏れ電流増大を抑制することができる。また電解質の増量を必要としないので、耐電圧を低下させることもない。
【００１６】
【実施例】
以下、本発明の実施例を具体的に説明する。表１、２に、本発明の実施例に係る電解液の組成、および３０℃における比抵抗を示す。
【００１７】
【表１】

【００１８】
【表２】

【００１９】
次に、表１、２に示す電解液を使用して、定格４００Ｖ−２２μＦ（φ１６×２５ｍｍＬ）のアルミニウム電解コンデンサを各１０個を作製し、ｔａｎδ、漏れ電流について初期特性測定後、高温無負荷試験（１０５℃、１０００時間放置）を行ったところ、表３に示す結果を得た。
【００２０】
【表３】

【００２１】
表３に示すように、フェニルアラニンを溶解しなかった従来例１〜３と比較し、本発明である実施例１〜９は高温無負荷試験において漏れ電流の増大が抑制され、優れた特性を示している。
【００２２】
ここで、フェニルアラニンの溶解量は０．１〜１．０ｗｔ％の範囲が好ましく、０．１ｗｔ％未満では十分な効果が得られず、低漏れ電流用途に不向きである。１．０ｗｔ％を超えると比抵抗が高くなる傾向にあり、低比抵抗用途に不向きとなる。
【００２３】
また、水の混合量は、２．０〜１０．０ｗｔ％の範囲が好ましく、２．０ｗｔ％未満では比抵抗がやや高いので、低比抵抗用途に不向きである。これに対して、水の混合量が１０．０ｗｔ％を超えると、フェニルアラニンの効果が低下する傾向にある。
【００２４】
本発明は、実施例に限定されるものではなく、先に例示したカルボン酸またはその塩を単独または複数溶解してもよく、耐洗浄剤としてニトロ化合物を溶解してもよい。
【００２５】
【発明の効果】
上記のとおり、本発明に係る電解液において、フェニルアラニンは、エチレングリコールなどの多価アルコールと水との混合溶媒に溶解し易く、かつ、電解液中の水の量を増加しても高温下でのアルミニウム電極箔と水との水和反応を抑制することができる。従って、電解コンデンサの特性改善並びに高温下での信頼性向上を図ることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in an electrolytic solution for driving an aluminum electrolytic capacitor (hereinafter, referred to as an electrolytic solution).
[0002]
[Prior art]
In recent years, with the miniaturization of electrolytic capacitors, those having a high etching ratio have been used as the anode foil of aluminum electrolytic capacitors, and accordingly, an electrolytic solution having a low specific resistance has been required. As such an electrolytic solution, conventionally, a solution in which ethylene glycol is used as a main solvent and an ammonium salt of a carboxylic acid is dissolved as an electrolyte is used (for example, see Patent Documents 1 and 2).
[0003]
[Patent Document 1]
Japanese Patent Publication No. 7-48460 (page 2, table)
[Patent Document 2]
Japanese Patent Publication No. 7-63047 (page 3, table 1)
[0004]
[Problems to be solved by the invention]
In order to obtain an electrolyte having a low specific resistance, it is necessary to increase the concentration of the electrolyte or to add a large amount of water. However, there is a problem that an increase in the concentration of the electrolyte causes the deposition of the electrolyte and a decrease in withstand voltage. Also, when a large amount of water is added, it is difficult to use the electrolytic capacitor at 105 ° C. because the leakage current of the electrolytic capacitor at high temperature and no load increases.
[0005]
An object of the present invention is to solve the above problems and to provide an electrolytic solution that can be used even under high temperature conditions.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, in the electrolytic solution for driving an electrolytic capacitor according to the present invention, phenylalanine is dissolved in the electrolytic solution to suppress a hydration reaction between the aluminum electrode foil and water at a high temperature. Provide an electrolyte with excellent reliability under load.
[0007]
That is, a carboxylic acid or a salt thereof and phenylalanine represented by the following chemical formula are dissolved in a solvent containing a polyhydric alcohol such as ethylene glycol and water.
[0008]
Embedded image

[0009]
In the electrolytic solution according to the present invention, since phenylalanine is dissolved, the hydration reaction between water and the electrode foil at a high temperature can be suppressed even when the amount of water mixed increases. Therefore, since the specific resistance can be lowered by adding water, it is not necessary to increase the amount of the electrolyte. Therefore, there is also an effect that the withstand voltage is not reduced.
[0010]
In the present invention, the amount of phenylalanine dissolved is preferably 0.1 to 1.0 wt% based on the entire electrolytic solution. When the added amount of phenylalanine is less than 0.1 wt%, a sufficient effect cannot be obtained, and when the added amount of phenylalanine exceeds 1.0 wt%, the specific resistance tends to increase.
[0011]
In the present invention, the mixing amount of water is preferably 2.0 to 10.0 wt% with respect to the entire electrolytic solution. If it is less than 2.0 wt%, the specific resistance is slightly high, and if it exceeds 10.0 wt%, the hydration reaction by phenylalanine tends not to be completely prevented.
[0012]
In the present invention, examples of the carboxylic acid include azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid, and 7-vinylhexadecene-1,16-dicarboxylic acid. .
[0013]
Examples of the carboxylic acid salts include ammonium salts, primary amine salts such as methylamine, ethylamine and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine and diethylamine, trimethylamine, diethylmethylamine and ethylamine. Examples include tertiary amine salts such as dimethylamine and triethylamine, and quaternary ammonium salts such as tetramethylammonium and triethylmethylammonium.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, a carboxylic acid or a salt thereof and phenylalanine are dissolved in a solvent containing a polyhydric alcohol such as ethylene glycol and water. Here, the amount of phenylalanine dissolved is 0.1 to 1.0 wt% based on the entire electrolytic solution. The mixing amount of water is set to 1.0 to 10.0 wt%.
[0015]
In such an electrolytic solution, since phenylalanine in the electrolytic solution is adsorbed on the electrode foil surface, the hydration reaction between water and the electrode foil at a high temperature of 105 ° C. can be suppressed even when the amount of added water increases, It is possible to suppress an increase in leakage current when no load is applied at a high temperature. Further, since it is not necessary to increase the amount of the electrolyte, the withstand voltage does not decrease.
[0016]
【Example】
Hereinafter, examples of the present invention will be specifically described. Tables 1 and 2 show the composition of the electrolytic solution and the specific resistance at 30 ° C. according to the examples of the present invention.
[0017]
[Table 1]

[0018]
[Table 2]

[0019]
Next, using the electrolytic solutions shown in Tables 1 and 2, ten aluminum electrolytic capacitors each having a rating of 400 V-22 μF (φ16 × 25 mmL) were prepared. After measuring the initial characteristics of tan δ and leakage current, When a test (leaving at 105 ° C. for 1000 hours) was performed, the results shown in Table 3 were obtained.
[0020]
[Table 3]

[0021]
As shown in Table 3, in comparison with Conventional Examples 1 to 3 in which phenylalanine was not dissolved, Examples 1 to 9 of the present invention exhibited excellent characteristics in which an increase in leakage current was suppressed in a high-temperature no-load test. ing.
[0022]
Here, the amount of phenylalanine dissolved is preferably in the range of 0.1 to 1.0 wt%, and if it is less than 0.1 wt%, a sufficient effect cannot be obtained, which is not suitable for low leakage current applications. If it exceeds 1.0 wt%, the specific resistance tends to be high, which is not suitable for low specific resistance applications.
[0023]
Further, the mixing amount of water is preferably in the range of 2.0 to 10.0 wt%, and if it is less than 2.0 wt%, the specific resistance is slightly high, so that it is not suitable for low specific resistance applications. On the other hand, when the mixing amount of water exceeds 10.0 wt%, the effect of phenylalanine tends to decrease.
[0024]
The present invention is not limited to the examples, and the carboxylic acid or the salt thereof exemplified above may be dissolved alone or plurally, and the nitro compound may be dissolved as a washing-resistant agent.
[0025]
【The invention's effect】
As described above, in the electrolytic solution according to the present invention, phenylalanine is easily dissolved in a mixed solvent of a polyhydric alcohol such as ethylene glycol and water, and at a high temperature even if the amount of water in the electrolytic solution is increased. Hydration reaction between the aluminum electrode foil and water can be suppressed. Therefore, it is possible to improve the characteristics of the electrolytic capacitor and improve the reliability at high temperatures.

Claims

An electrolytic solution for driving an electrolytic capacitor, wherein a carboxylic acid or a salt thereof and phenylalanine represented by the following chemical formula are dissolved in a solvent containing a polyhydric alcohol and water.

2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the amount of phenylalanine dissolved is 0.1 to 1.0 wt% with respect to the entire electrolytic solution.

3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein a mixing amount of water is 2.0 to 10.0 wt% with respect to the whole electrolytic solution.