JP2004186188A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte for driving an electrolytic capacitor which is low in resistivity and improved in stability under the condition of high temperature. <P>SOLUTION: An organic carboxylic acid or its salt and 0.01 to 5.0 wt.% isoleucine represented by formula 1 are dissolved into a mixed solvent of ethylene glycol and water. Besides, adipic acid, benzoic acid. sebasic acid, azelaic acid, phthalic acid, maleic acid, borodisalicylic acid or the like can be used as the organic carboxylic acid. Besides ammonium salt, salt of primary amine, such as methylamine, ethylamine, t-butylamine or the like, salt of secondary amine, such as dimethylamine, ethyl methylamine, diethylamine or the like, salt of tertiary amine, such as triethylamine, diethyl methylamine, triethylamine or the like, and salt of quaternary ammonium, such as tetra-methyl ammonium, triethyl methyl ammonium or the like can be used as salt of organic carboxylic acid. An electrolytic capacitor using this electrolyte can be kept high in electric stability and can prevent troubles from occurring in its external appearance. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００６】
本発明において、上記イソロイシンの溶解量が、電解液全体に対して０．０１〜５．０重量％であることが好ましい。０．０１重量％未満では電極箔の保護効果が充分でなく、５．０重量％を超えると電解液の比抵抗が高くなる。
【０００７】
本発明において、上記水の混合量が、電解液全体に対して２０．０〜８０．０重量％であることが好ましい。水の混合量は、２０重量％未満では比抵抗が高くなり、８０．０重量％を超えると熱的安定性が低下する。
【０００８】
なお、上記有機カルボン酸として、アジピン酸の他、安息香酸、セバシン酸、アゼライン酸、フタル酸、マレイン酸、サリチル酸、ボロジサリチル酸等を挙げることができる。
【０００９】
そして、上記有機カルボン酸の塩として、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挙げることができる。
【００１０】
【発明の実施の形態】
本発明に係る電解液では、エチレングリコールと水とを含む混合溶媒に、上記の有機カルボン酸またはその塩と、イソロイシンとを溶解する。ここで、イソロイシンの溶解量は、電解液全体に対して０．０１〜５．０重量％とする。
このような電解液において、イソロイシンは、高温条件下での電解液と電極箔の反応を抑制することでガス発生を抑え、電解コンデンサの電気特性も長期間安定に保つことができる。
【００１１】
【実施例】
以下、本発明を実施例に基づき具体的に説明する。
表１に示す組成で電解液を調合し、３０℃における電解液の比抵抗を測定した結果を表１に示す。
【００１２】
【表１】

【００１３】
表１に示す電解液をそれぞれコンデンサ素子に含浸し、直径１０ｍｍ、長さ１２．５ｍｍ、定格電圧６．３ｖ、静電容量１０００μＦのアルミニウム電解コンデンサを各１０個作製した。
次に、上記のコンデンサを１０５℃の恒温槽中で定格電圧を３０００時間印加し、初期値に対する静電容量変化率、ｔａｎδ、漏れ電流を測定し、表２の結果を得た。
【００１４】
【表２】

【００１５】
表２に示すように、イソロイシンを溶解した実施例は、３０００時間経過後も電気特性を測定することができたが、従来例は１０００時間までに防爆弁が作動しており、本発明による電解液が優れていることが分かる。
【００１６】
なお、イソロイシンの配合量は、０．００１重量％では電極箔の保護効果が充分でなく、１０．０重量％では電解液の比抵抗が高くなるので、低比抵抗を重視する用途には不適である。従って、イソロイシンの配合量は、０．０１〜５．０重量％の範囲が好ましい。
【００１７】
また、水の混合量は１０．０重量％では低比抵抗用途には不適であり、９０．０重量％ではイソロイシンの効果が不十分となる。したがって、水の混合量は２０．０〜８０．０重量％の範囲が好ましい。
【００１８】
本発明は、実施例に限定されるものではなく、先に例示した有機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、必要により耐洗浄剤としてニトロ化合物を溶解してもよい。
【００１９】
【発明の効果】
以上説明したように、本発明によるエチレングリコールと水との混合溶媒にイソロイシンを溶解した電解液を使用した電解コンデンサは、高温条件下での電気特性の安定化に優れた効果を示し、外観異常の発生も防ぐことができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electrolytic solution for driving an electrolytic capacitor (hereinafter, referred to as an electrolytic solution), and particularly to a mixed solvent system of ethylene glycol and water.
[0002]
[Prior art]
The aluminum electrolytic capacitor has tab terminals attached to the anode foil and the cathode foil whose aluminum foil surface is roughened, and impregnated with electrolytic solution in a capacitor element obtained by winding these foils through a separator paper. It has a hermetically sealed structure by incorporating it into an aluminum outer case together with a rubber sealing body and sealing the outer case.
Among the electrolytes used in such electrolytic capacitors, the electrolytes used for low impedance applications are required to have a low specific resistance, and have a specific resistance of 50 to 50% by adding water as a solvent to about 20 to 40% by weight. An electrolyte of 90 Ω · cm is used (for example, see Patent Documents 1 and 2).
[0003]
[Patent Document 1]
Patent No. 2709321 (page 3, table 1)
[Patent Document 2]
JP-A-9-186052 (Page 4, Tables 1 and 2)
[0004]
[Problems to be solved by the invention]
In recent years, it has been required to further reduce the specific resistance of the electrolytic solution. However, when water is added in an amount of 20% by weight or more in order to achieve a low specific resistance, the electrolytic solution and the electrolytic foil react under high-temperature conditions to generate gas. There was a problem that the electrical characteristics deteriorated.
In view of the above problems, an object of the present invention is to provide an electrolytic solution for driving an electrolytic capacitor which has low specific resistance and can improve stability under high temperature conditions.
[0005]
[Means for Solving the Problems]
The present invention dissolves isoleucine in a mixed solvent of ethylene glycol and water, thereby stabilizing the electrical characteristics of an electrolytic capacitor even under high temperature conditions while reducing the specific resistance of an electrolytic solution. is there.
That is, the electrolytic solution according to the present invention is characterized in that an organic carboxylic acid or a salt thereof and isoleucine represented by the following chemical formula are dissolved in a mixed solvent containing ethylene glycol and water.
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[0006]
In the present invention, the amount of the isoleucine dissolved is preferably 0.01 to 5.0% by weight based on the whole electrolytic solution. If it is less than 0.01% by weight, the protective effect of the electrode foil is not sufficient, and if it exceeds 5.0% by weight, the specific resistance of the electrolytic solution becomes high.
[0007]
In the present invention, the mixing amount of the water is preferably 20.0 to 80.0% by weight based on the whole electrolytic solution. If the mixing amount of water is less than 20% by weight, the specific resistance increases, and if it exceeds 80.0% by weight, the thermal stability decreases.
[0008]
Examples of the organic carboxylic acids include benzoic acid, sebacic acid, azelaic acid, phthalic acid, maleic acid, salicylic acid, and borodisalicylic acid, in addition to adipic acid.
[0009]
And, as the salt of the organic carboxylic acid, in addition to ammonium salt, methylamine, ethylamine, primary amine salts such as t-butylamine, dimethylamine, ethylmethylamine, secondary amine salts such as diethylamine, trimethylamine, diethylmethylamine, Examples include tertiary amine salts such as ethyldimethylamine and triethylamine, and quaternary ammonium salts such as tetramethylammonium and triethylmethylammonium.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
In the electrolytic solution according to the present invention, the organic carboxylic acid or its salt and isoleucine are dissolved in a mixed solvent containing ethylene glycol and water. Here, the amount of isoleucine dissolved is 0.01 to 5.0% by weight based on the whole electrolyte.
In such an electrolytic solution, isoleucine can suppress gas generation by suppressing the reaction between the electrolytic solution and the electrode foil under a high temperature condition, and can keep the electrical characteristics of the electrolytic capacitor stable for a long time.
[0011]
【Example】
Hereinafter, the present invention will be specifically described based on examples.
An electrolytic solution having the composition shown in Table 1 was prepared, and the specific resistance of the electrolytic solution at 30 ° C. was measured.
[0012]
[Table 1]

[0013]
The electrolytic solution shown in Table 1 was impregnated into each of the capacitor elements, and ten aluminum electrolytic capacitors each having a diameter of 10 mm, a length of 12.5 mm, a rated voltage of 6.3 V, and a capacitance of 1000 μF were produced.
Next, a rated voltage was applied to the capacitor in a thermostat at 105 ° C. for 3,000 hours, and the capacitance change rate, tan δ, and leakage current with respect to the initial value were measured, and the results in Table 2 were obtained.
[0014]
[Table 2]

[0015]
As shown in Table 2, in the example in which isoleucine was dissolved, the electrical characteristics could be measured even after 3000 hours. However, in the conventional example, the explosion-proof valve was operated by 1000 hours, and the electrolysis according to the present invention was performed. It turns out that the liquid is excellent.
[0016]
When the amount of isoleucine is 0.001% by weight, the effect of protecting the electrode foil is not sufficient, and when the amount is 10.0% by weight, the specific resistance of the electrolytic solution becomes high. It is. Therefore, the amount of isoleucine is preferably in the range of 0.01 to 5.0% by weight.
[0017]
Further, if the mixing amount of water is 10.0% by weight, it is unsuitable for low specific resistance use, and if the mixing amount is 90.0% by weight, the effect of isoleucine becomes insufficient. Therefore, the mixing amount of water is preferably in the range of 20.0 to 80.0% by weight.
[0018]
The present invention is not limited to the examples, and the organic carboxylic acids or salts thereof exemplified above may be dissolved alone or in combination, and if necessary, the nitro compound may be dissolved as a detergent.
[0019]
【The invention's effect】
As described above, the electrolytic capacitor using the electrolytic solution in which isoleucine is dissolved in a mixed solvent of ethylene glycol and water according to the present invention has an excellent effect of stabilizing electric characteristics under high temperature conditions, and has an abnormal appearance. Can also be prevented from occurring.

Claims (3)

An electrolytic solution for driving an electrolytic capacitor, wherein an organic carboxylic acid or a salt thereof and isoleucine represented by the following chemical formula are dissolved in a mixed solvent containing ethylene glycol and water.

2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the dissolved amount of isoleucine is 0.01 to 5.0% by weight based on the whole electrolytic solution. 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein a mixing amount of water is 20.0 to 80.0% by weight based on the whole electrolytic solution.