JP2004235593A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic capacitor driving electrolyte capable of improving withstand voltage while suppressing the increase of specific resistance. <P>SOLUTION: When ethyleneglycol is used as a main solvent and carboxylic acid or its salt and quinacridone shown in the figure are solved at a concentration of 0.1-5.0 wt%, chemical reaction between electrolyte and an electrode foil can be suppressed and the withstand voltage of the electrolyte can be improved. Formic acid, benzoic acid, salicylic acid, maleic acid, phthalic acid, succinic acid, azelaic acid, sebacic acid, 1, 6-decanedicarboxylic acid, etc. can be illustrated as carboxylic acid and ammonium salt, primary amine salt such as methylamine and ethylamine, secondary amine salt such as dimethyl amine and ethyl-methylamine, tertiary amine salt such as trimethylamine and dimethyl amine, and quaternary ammonium salt such as tetramethyl ammonium and trimethyl ammonium, imidazolinium salt, etc. can be shown as examples, as carboxylic salts. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００７】
また、上記キナクリドンの溶解量が、０．１〜５．０ｗｔ％であることを特徴とする電解コンデンサの駆動用電解液である。
【０００８】
カルボン酸としては、ギ酸、酢酸、ラウリン酸、ステアリン酸、デカン酸、安息香酸、サリチル酸、マレイン酸、フタル酸、フマル酸、コハク酸、グルタル酸、アゼライン酸、セバシン酸、２−メチルアゼライン酸、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】
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、イミダゾリニウム塩等を例示することができる。
【００１０】
エチレングリコールに混合する副溶媒としては、水の他、プロピレングリコール等のグリコール類、γ−ブチロラクトン、Ｎ−メチル−２−ピロリドン等のラクトン類、Ｎ−メチルホルムアミド、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ−エチルホルムアミド、Ｎ，Ｎ−ジエチルホルムアミド、Ｎ−メチルアセトアミド、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ−エチルアセトアミド、Ｎ，Ｎ−ジエチルアセトアミド、ヘキサメチルホスホリックアミド等のアミド類、エチレンカーボネート、プロピレンカーボネート、イソブチレンカーボネート等の炭酸類、アセトニトリル等のニトリル類、ジメチルスルホキシド等のオキシド類、エーテル類、ケトン類、エステル類、スルホラン、スルホラン誘導体等を例示することができる。これらの溶媒は一種類だけでなく、二種類以上を混合して使用することもできる。
【００１１】
上記の電解液には、漏れ電流の低減、耐電圧向上、ガス吸収等の目的で種々の添加剤を加えることができる。添加剤の例として、リン酸化合物、ホウ酸化合物、多価アルコール類、ポリビニルアルコール、ポリエチレングリコール、ポリプロピレングリコール、ポリオキシエチレンポリオキシプロピレングリコールのランダム共重合体およびブロック共重合体に代表される高分子化合物、ニトロ化合物等が挙げられる。
【００１２】
【発明の実施の形態】
エチレングリコールを主溶媒とする電解液中で、キナクリドンのキノン部分が電極箔の酸化皮膜と反応し耐水性の皮膜を形成するため、電解液と電極箔との化学反応が抑えられ、耐電圧向上を図ることができる。
また、キナクリドンが芳香族環を有することで、高温での安定性も高められ、エチレングリコールを主成分とする溶媒に対して溶解性が高く、主溶質のカルボン酸とのエステル化反応が少ないことから、比抵抗の上昇を抑えながら耐電圧の向上をも図ることができる。
【００１３】
【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の組成で電解液を調合し、３０℃における電解液の比抵抗と８５℃における火花発生電圧（電解液の耐電圧）を測定し、表１、２の結果を得た。
【００１４】
【表１】

【００１５】
【表２】

【００１６】
表１，２より、キナクリドンを溶解した実施例は、従来例より比抵抗の上昇が抑えられ、耐電圧が向上していることが分かる。キナクリドンの溶解量が０．１ｗｔ％未満では耐電圧向上の効果が十分でなく、５．０ｗｔ％を超えると比抵抗が高くなり過ぎ、低比抵抗用途に不向きとなる。よって、キナクリドンの溶解量は、０．１〜５．０ｗｔ％の範囲が好ましい。
【００１７】
なお、本発明は実施例に限定されるものではなく、先に例示した各種溶質を単独または複数溶解した電解液や、その他添加剤を加えた電解液、副溶媒を混合した電解液でも実施例と同等の効果があった。
【００１８】
【発明の効果】
上記のとおり、本発明によるキナクリドンを溶解した電解液は、主溶質のカルボン酸とのエステル化反応が少なく、エチレングリコールに対する溶解性が高いので、比抵抗の上昇を抑制しながら、耐電圧の向上を図ることができ、かつ熱安定性にも優れるため、高温下での製品の信頼性を高めることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in an electrolytic solution for driving an electrolytic capacitor (hereinafter, referred to as an electrolytic solution), and more particularly to an electrolytic solution having improved withstand voltage.
[0002]
[Prior art]
Conventionally, an electrolytic solution for a medium-to-high pressure aluminum electrolytic capacitor has been prepared by dissolving carboxylic acid or its ammonium salt, boric acid or its ammonium salt, and a polyhydric alcohol such as mannitol in a solvent such as ethylene glycol. And polyhydric alcohols form an ester compound, and it is known that the withstand voltage of the electrolytic solution is improved by its structural characteristics. In order to further improve the withstand voltage, polyvinyl alcohol which is a synthetic polymer was dissolved (for example, see Patent Documents 1 to 3).
[0003]
[Patent Document 1]
Japanese Patent Publication No. 7-48459 (pages 1-4)
[Patent Document 2]
Japanese Patent Publication No. 7-48460 (pages 1-3)
[Patent Document 3]
Japanese Patent Publication No. 7-63047 (pages 1-4)
[0004]
[Problems to be solved by the invention]
However, even if the amount of mannitol or sorbitol having about 6 carbon atoms is increased, the withstand voltage of the electrolytic solution is slowly improved even when the added amount is increased. . On the other hand, polyvinyl alcohol can improve the withstand voltage of the electrolyte by adding a smaller amount than mannitol, but it cannot be added in a large amount because the solubility in a solvent containing ethylene glycol as a main component is extremely low. There is a problem that stirring is required for a long time. In addition, since polyhydric alcohols may cause an ester reaction with carboxylic acid as a main solute, there is a problem that the characteristic change of the electrolytic solution itself is increased.
The present invention solves the above-mentioned problems, and provides an electrolytic solution for an electrolytic capacitor capable of improving the withstand voltage while suppressing a rise in specific resistance.
[0005]
[Means for Solving the Problems]
The present invention has been found as a result of various studies to solve the above-described problems, and has been found.The quinacridone has a quinone skeleton, and this structure suppresses a chemical reaction between the electrolytic solution and the electrode foil. , It is intended to increase the withstand voltage.
That is, it is an electrolytic solution for driving an electrolytic capacitor, characterized by dissolving a carboxylic acid or a salt thereof and quinacridone (formula 2) using ethylene glycol as a main solvent.
[0006]
Embedded image

[0007]
Further, the present invention provides an electrolytic solution for driving an electrolytic capacitor, wherein the amount of quinacridone dissolved is 0.1 to 5.0 wt%.
[0008]
As the carboxylic acid, formic acid, acetic acid, lauric acid, stearic acid, decanoic acid, benzoic acid, salicylic acid, maleic acid, phthalic acid, fumaric acid, succinic acid, glutaric acid, azelaic acid, sebacic acid, 2-methylazelaic acid, Examples thereof include 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid, and 7-vinylhexadecene-1,16-dicarboxylic acid.
[0009]
Examples of 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 ethyldimethylamine. And tertiary amine salts such as triethylamine, quaternary ammonium salts such as tetramethylammonium, triethylmethylammonium and tetraethylammonium, and imidazolinium salts.
[0010]
Examples of the secondary solvent mixed with ethylene glycol include water, glycols such as propylene glycol, lactones such as γ-butyrolactone, N-methyl-2-pyrrolidone, N-methylformamide, N, N-dimethylformamide, N Amides such as -ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N, N-diethylacetamide, hexamethylphosphoramide, ethylene carbonate, propylene carbonate And carbonic acids such as isobutylene carbonate, nitriles such as acetonitrile, oxides such as dimethylsulfoxide, ethers, ketones, esters, sulfolane, and sulfolane derivatives. These solvents can be used alone or in combination of two or more.
[0011]
Various additives can be added to the above electrolyte for the purpose of reducing leakage current, improving withstand voltage, absorbing gas, and the like. Examples of additives include phosphoric acid compounds, boric acid compounds, polyhydric alcohols, polyvinyl alcohols, polyethylene glycols, polypropylene glycols, and random copolymers and block copolymers of polyoxyethylene polyoxypropylene glycol. Molecular compounds, nitro compounds and the like can be mentioned.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
In the electrolyte containing ethylene glycol as the main solvent, the quinone part of quinacridone reacts with the oxide film on the electrode foil to form a water-resistant film, thereby suppressing the chemical reaction between the electrolyte and the electrode foil and improving the withstand voltage. Can be achieved.
In addition, since quinacridone has an aromatic ring, the stability at high temperatures is also improved, the solubility in a solvent containing ethylene glycol as a main component is high, and the esterification reaction with the carboxylic acid of the main solute is small. Therefore, the withstand voltage can be improved while suppressing an increase in the specific resistance.
[0013]
【Example】
Hereinafter, the present invention will be specifically described based on examples. An electrolyte was prepared using the composition shown in Table 1, and the specific resistance of the electrolyte at 30 ° C. and the spark generation voltage at 85 ° C. (withstand voltage of the electrolyte) were measured. The results shown in Tables 1 and 2 were obtained.
[0014]
[Table 1]

[0015]
[Table 2]

[0016]
From Tables 1 and 2, it can be seen that in Examples in which quinacridone was dissolved, the increase in specific resistance was suppressed and the withstand voltage was improved as compared with the conventional example. If the amount of quinacridone dissolved is less than 0.1 wt%, the effect of improving the withstand voltage is not sufficient, and if it exceeds 5.0 wt%, the specific resistance becomes too high, which is unsuitable for low specific resistance applications. Therefore, the amount of quinacridone dissolved is preferably in the range of 0.1 to 5.0 wt%.
[0017]
In addition, the present invention is not limited to the examples, the electrolyte solution in which various solutes exemplified above alone or plurally dissolved, the electrolyte solution to which other additives are added, and the electrolyte solution in which a sub-solvent is mixed. There was an effect equivalent to.
[0018]
【The invention's effect】
As described above, the electrolytic solution in which quinacridone is dissolved according to the present invention has a low esterification reaction with the carboxylic acid of the main solute and a high solubility in ethylene glycol. Therefore, the reliability of the product at a high temperature can be improved.

Claims (2)

An electrolytic solution for driving an electrolytic capacitor, comprising ethylene glycol as a main solvent and dissolving a carboxylic acid or a salt thereof and quinacridone (formula 1).

An electrolytic solution for driving an electrolytic capacitor, wherein the amount of quinacridone according to claim 1 is 0.1 to 5.0 wt%.