JP4214008B2 - Electrolytic solution for electrolytic capacitor drive - Google Patents

Description

【０００８】
有機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。
【０００９】
また、有機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、テトラエ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。
【００１０】
【発明の実施の形態】
フェナントレンキノンは電極箔表面に効率良く皮膜を形成するため、電解液の比抵抗上昇を抑制しながら、少量の添加で耐電圧を向上させることができる。平均分子量が１０００を超えるポリエチレングリコールの場合、溶解性が低下し、１０．０ｗｔ％の溶解が限界であったが、フェナントレンキノンはエチレングリコールに対する溶解性が高く、容易に電解液に溶解する。また、熱に対しても分解しにくく、高温での製品の特性安定化を図ることができる。
【００１１】
【実施例】
以下、本発明の実施例を具体的に説明する。表１〜３の組成で電解液を調合し、３０℃における比抵抗および８５℃における火花発生電圧（電解液の耐電圧）を測定した。
【００１２】
【表１】

【００１３】
【表２】

【００１４】
【表３】

【００１５】
まず、有機カルボン酸を１，６−デカンジカルボン酸とした場合の実施例１〜６と従来例１〜５を比較した場合について説明する。
ポリエチレングリコールを１．０ｗｔ％溶解した従来例２と、ポリビニルアルコールを１．０ｗｔ％溶解した従来例５と、９，１０−フェナントレンキノンを１．０ｗｔ％溶解した実施例３とを比較すると、比抵抗は同等ながら火花発生電圧を向上することができた。さらに、これらを増量し、ポリエチレングリコールを１０．０ｗｔ％溶解した従来例３と、９，１０−フェナントレンキノンを１０．０ｗｔ％溶解した実施例５とを比較すると、実施例５では従来例３より比抵抗が１４０Ω・ｃｍ低く、火花発生電圧は１０Ｖ高くなり、特性改善されていることが分かる。また、ポリビニルアルコールを１０．０ｗｔ％加えた従来例５では溶解しなかった。
【００１６】
ただし、９，１０−フェナントレンキノンの電解液に対する溶解量は０．１〜１０．０ｗｔ％の範囲が好ましく、０．１ｗｔ％未満では十分な効果が得られず、１０．０ｗｔ％を超えると電解液の比抵抗が高くなるので、低比抵抗用途に不向きとなる。
【００１７】
なお、有機カルボン酸をセバシン酸アンモニウムとした場合も、上記と同様、火花発生電圧が向上していることが分かる（実施例７〜１２と従来例７とを比較）。
また、実施例２と実施例８を比較すると、上記の１，６−デカンジカルボン酸の場合より比抵抗レベルは３０Ω・ｃｍ下がるが、火花発生電圧も１０Ｖ低下する。よって、より低比抵抗を要求され、耐圧は若干低くてもよい場合に適している（実施例７〜１２）。
【００１８】
タブ端子を陽極箔および陰極箔に固着し、セパレータを介して巻回したコンデンサ素子に、従来例１〜３、５、実施例１〜６の電解液を各々含浸し、直径３５．０ｍｍ、長さ４０．０ｍｍ、定格電圧４５０Ｖ、静電容量３９０μＦの電解コンデンサを各１０個作製しエージングを行った。
これらの製品を １０５℃の恒温槽中で定格電圧を２０００時間印加し、ｔａｎδを測定し、表４の結果を得た。
【００１９】
【表４】

【００２０】
表４より本発明の９，１０−フェナントレンキノンを溶解した実施例１〜６は、製品のｔａｎδ上昇が抑えられ、かつショートパンクが発生していないことから、高温で長時間電解液の比抵抗上昇と耐電圧の低下が抑制されていることが分かる。しかし、フェナントレンキノンを溶解しなかった従来例１は、製品のｔａｎδ上昇が大きく、２０００時間までにショートパンクが発生し、また、ポリエチレングリコールを溶解した従来例２、３、ポリビニルアルコールを溶解した従来例５では、実施例と比べてｔａｎδ上昇が大きかった。
【００２１】
また、上記の９，１０−フェナントレンキノン以外に、１，２−フェナントレンキノン、１，４−フェナントレンキノン、３，４−フェナントレンキノンを溶解した電解液にあっても、上記と同様の効果が得られた。
【００２２】
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やその塩を単独または複数混合しても本実施例と同等の効果があり、さらに、先に例示した溶媒を、目的により混合しても本実施例と同等の効果が得られる。
【００２３】
【発明の効果】
上記のとおり、本発明で使用するフェナントレンキノンは、エチレングリコールに易溶であり、フェナントレンキノンを溶解した電解液は、電解液の耐電圧の向上を図ることができ、かつ高温で長時間電解液の比抵抗上昇と耐電圧低下を抑制できるので、製品のｔａｎδ増加およびショートパンク発生を抑えることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as an electrolytic solution).
[0002]
[Prior art]
Conventionally, electrolytes for medium- and high-voltage electrolytic capacitors use ethylene glycol as the main solvent, dissolve organic carboxylic acid or its ammonium salt, boric acid or its ammonium salt, and dissolve polyhydric alcohols such as mannitol and sorbitol. Thus, the one having improved the withstand voltage of the electrolytic solution has been used (see, for example, Patent Documents 1 and 2).
[0003]
[Patent Document 1]
Japanese Patent Publication No. 7-48460 (2nd page, table)
[Patent Document 2]
Japanese Patent Publication No. 7-63047 (Page 3, Table 1)
[0004]
[Problems to be solved by the invention]
However, synthetic polymers such as polyethylene glycol and polyvinyl alcohol having an average molecular weight of 1000 or more have a high effect of improving the withstand voltage, but have a large increase in specific resistance and solubility in an electrolytic solution containing ethylene glycol as a main solvent. There was a problem that it was very low.
In addition, the addition of a synthetic polymer such as polyvinyl alcohol has a problem that the main chain of the polymer is cut by heat and oxygen inside the product, and the initial withstand voltage cannot be maintained for a long time.
Therefore, there has been a demand for an electrolytic solution that can improve the withstand voltage while suppressing an increase in specific resistance, has high electrolyte solubility, and is stable at high temperatures.
[0005]
[Means for Solving the Problems]
The present invention has been found as a result of various studies to solve the above problems, and an electrolyte solution in which phenanthrenequinone having a high solubility in ethylene glycol is dissolved has a low specific resistance and a high withstand voltage. It has the advantage of being stable at high temperatures.
That is, the present invention is ethylene glycol as a main solvent, and an organic carboxylic acid or a salt thereof, and boric acid or its ammonium salt, were dissolved and phenanthrenequinone represented by the following chemical formula, of the phenanthrenequinone for the entire electrolyte An electrolytic solution for driving an electrolytic capacitor characterized in that the dissolution amount is 0.1 to 10.0 wt% .
[0006]
[Chemical formula 2]

[0008]
Examples of the organic carboxylic acid include azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid, 7-vinylhexadecene-1,16-dicarboxylic acid and the like.
[0009]
In addition to ammonium salts, organic carboxylic acid salts include primary amine salts such as methylamine, ethylamine, and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine, and diethylamine, trimethylamine, diethylmethylamine, Examples thereof include tertiary amine salts such as ethyldimethylamine and triethylamine, and quaternary ammonium salts such as tetramethylammonium, triethylmethylammonium and tetraethylammonium.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Since phenanthrenequinone efficiently forms a film on the surface of the electrode foil, the withstand voltage can be improved with a small amount of addition while suppressing an increase in the specific resistance of the electrolytic solution. In the case of polyethylene glycol having an average molecular weight of more than 1000, the solubility is lowered and 10.0 wt% is the limit, but phenanthrenequinone is highly soluble in ethylene glycol and easily dissolves in the electrolyte. In addition, it is difficult to decompose against heat, and the product characteristics can be stabilized at high temperatures.
[0011]
【Example】
Examples of the present invention will be specifically described below. Electrolytic solutions were prepared with the compositions shown in Tables 1 to 3, and the specific resistance at 30 ° C. and the spark generation voltage at 85 ° C. (withstand voltage of the electrolytic solution) were measured.
[0012]
[Table 1]

[0013]
[Table 2]

[0014]
[Table 3]

[0015]
First, the case where Examples 1-6 when the organic carboxylic acid is 1,6-decanedicarboxylic acid and the prior art examples 1-5 are compared is demonstrated.
Comparing Conventional Example 2 in which polyethylene glycol was dissolved at 1.0 wt%, Conventional Example 5 in which polyvinyl alcohol was dissolved at 1.0 wt%, and Example 3 in which 9,10-phenanthrenequinone was dissolved at 1.0 wt%, The spark generation voltage could be improved with the same resistance. Furthermore, when these amounts were increased and Conventional Example 3 in which polyethylene glycol was dissolved by 10.0 wt% and Example 5 in which 9,10-phenanthrenequinone was dissolved by 10.0 wt% were compared, Example 5 was more than Conventional Example 3 The specific resistance is 140 Ω · cm low and the spark generation voltage is 10 V higher, indicating that the characteristics have been improved. Moreover, it did not melt | dissolve in the prior art example 5 which added 10.0 wt% of polyvinyl alcohol.
[0016]
However, the amount of 9,10-phenanthrenequinone dissolved in the electrolytic solution is preferably in the range of 0.1 to 10.0 wt%, and if it is less than 0.1 wt%, a sufficient effect cannot be obtained. Since the specific resistance of a liquid becomes high, it becomes unsuitable for a low specific resistance use.
[0017]
In addition, when organic carboxylic acid is ammonium sebacate, it turns out that the spark generation voltage is improving similarly to the above (Examples 7-12 and the prior art example 7 are compared).
Further, when Example 2 and Example 8 are compared, the specific resistance level is 30 Ω · cm lower than that in the case of 1,6-decanedicarboxylic acid, but the spark generation voltage is also reduced by 10V. Therefore, it is suitable when a lower specific resistance is required and the withstand voltage may be slightly lower (Examples 7 to 12).
[0018]
Capacitor elements each having a tab terminal fixed to an anode foil and a cathode foil and wound through a separator were impregnated with the electrolytic solutions of Conventional Examples 1 to 3, 5 and Examples 1 to 6, respectively, and had a diameter of 35.0 mm and a length. Ten electrolytic capacitors each having a thickness of 40.0 mm, a rated voltage of 450 V, and a capacitance of 390 μF were produced and aged.
The rated voltage was applied to these products in a constant temperature bath at 105 ° C. for 2000 hours, tan δ was measured, and the results shown in Table 4 were obtained.
[0019]
[Table 4]

[0020]
From Table 4, in Examples 1 to 6, in which 9,10-phenanthrenequinone of the present invention was dissolved, the increase in tan δ of the product was suppressed and no short puncture occurred, so the specific resistance of the electrolyte solution at high temperature for a long time. It can be seen that the increase and the decrease in withstand voltage are suppressed. However, in Conventional Example 1 in which phenanthrenequinone was not dissolved, the increase in tan δ of the product was large, and short puncture occurred by 2000 hours, and in Conventional Examples 2 and 3 in which polyethylene glycol was dissolved, and in the conventional example in which polyvinyl alcohol was dissolved. In Example 5, the increase in tan δ was larger than that in Example.
[0021]
In addition to the 9,10-phenanthrenequinone described above, the same effect as described above can be obtained even in an electrolyte solution in which 1,2-phenanthrenequinone, 1,4-phenanthrenequinone, and 3,4-phenanthrenequinone are dissolved. It was.
[0022]
The present invention is not limited to the examples, and even if the organic carboxylic acids and salts thereof exemplified above are used alone or in combination, the same effects as those of the examples can be obtained. Even if they are mixed depending on the purpose, the same effect as in this embodiment can be obtained.
[0023]
【The invention's effect】
As described above, the phenanthrenequinone used in the present invention is easily soluble in ethylene glycol, and the electrolytic solution in which phenanthrenequinone is dissolved can improve the withstand voltage of the electrolytic solution, and can be used at a high temperature for a long time. Therefore, the increase in tan δ of the product and the occurrence of short puncture can be suppressed.

Claims (1)

Using ethylene glycol as the main solvent, dissolving an organic carboxylic acid or salt thereof, boric acid or ammonium salt thereof, and phenanthrenequinone represented by the following chemical formula ,
An electrolytic solution for driving an electrolytic capacitor, wherein the amount of the phenanthrenequinone dissolved in the entire electrolytic solution is 0.1 to 10.0 wt% .