JPH0661102A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain the electrolyte for an electrolytic capacitor having the dielectric strength which can be used at high voltage by adding trioxyethylene diglycolic acid or its salt into the solvent mainly composed of an organic polar solvent. CONSTITUTION:The trioxyethylene diglycolic acid or its salt, which is indicated by the formula separately mentioned, is added as a solute to the solvent formed by mainly combining the protic polar solvent such as ethylene glycol and butanediol. It is desirable that ammonium spilt is used for the salt to be used, and also it is desirable to add about 1 to 30wt.% of trioxyethylene diglycolic acid or its salt against the electrolyte for electrolytic capacitor. As a result, an electrolytic capacitor electrolyte, which can be used at high voltage of 550V or higher, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement in electrolytic solution for electrolytic capacitors, and more specifically, it is used at high voltage by adding trioxyethylenediglycolic acid or its salt as a solute to electrolytic solution for electrolytic capacitors. The present invention relates to an electrolytic solution for an electrolytic capacitor that realizes possible withstand voltage.

[0002]

2. Description of the Related Art An electrolytic solution for electrolytic capacitors uses a valve metal, such as aluminum or tantalum, having an insulating oxide film formed on its surface as an anode electrode, and uses the oxide film layer as a dielectric material. The surface of the electrode is brought into contact with an electrolytic solution to form an electrolyte layer, and a current collecting electrode usually called a cathode is arranged.

The electrolytic solution for electrolytic capacitors is in direct contact with the dielectric layer as described above and acts as a true cathode. That is, the electrolytic solution is interposed between the dielectric layer of the electrolytic capacitor and the collecting cathode, and the resistance of the electrolytic solution is inserted in series with the electrolytic capacitor. Therefore, the characteristics of the electrolytic solution are a major factor influencing the characteristics of the electrolytic capacitor.

In the prior art of electrolytic capacitors, azelaic acid, sebacic acid, decanedicarboxylic acid or salts thereof have been used as the solute of the electrolytic solution for high voltage electrolytic capacitors.

[0005]

However, at present, in these known techniques, an electrolytic capacitor having a withstand voltage property capable of withstanding a high voltage exceeding 550 V has not been obtained.

Therefore, an object of the present invention is to provide an electrolytic solution for an electrolytic capacitor, which realizes a withstand voltage property that can be used at a high voltage exceeding 550V.

[0007]

Means for Solving the Problems As a result of intensive studies on the electrolytic solution of the electrolytic capacitor, the present inventors have found that by adding trioxyethylenediglycolic acid or its salt as a solute, a high voltage exceeding 550V can be obtained. It has been found that an electrolytic capacitor that realizes withstand voltage that can be used in is obtained.

Therefore, according to the present invention, a compound represented by the general formula:

[0009]

[Chemical 2]

There is provided an electrolytic solution for an electrolytic capacitor, characterized in that trioxyethylene diglycolic acid or a salt thereof represented by is added as a solute.

In the present invention, both trioxyethylenediglycolic acid and its salt can be used simultaneously, or each can be used alone.
Ammonium salt is preferable as the salt to be used. The amount of trioxyethylene diglycolic acid or its salt to be used is preferably about 1% by weight to about 30% by weight with respect to the electrolytic solution for electrolytic capacitors.

When trioxyethylene diglycolic acid or its salt is added to the electrolytic solution for electrolytic capacitors, the withstand voltage that can be used at high voltage of electrolytic capacitors is improved by about 10% or more as compared with conventional solutes. , 600V or more.

As the organic polar solvent, a solvent in which a protic polar solvent glycol is mainly combined is generally used, but an aprotic polar solvent can also be used. Examples of the organic polar solvent include (1) protic polar solvent: (1-1) monohydric alcohols ethanol, propanol, butanol, pentanol, hexanol, cyclobutanol, cyclopentanol, cyclohexanol, benzyl alcohol (1-2) ) Polyhydric alcohols and oxyalcohol compounds Ethylene glycol, propylene glycol, glycerin, methyl cellosolve (methoxyethanol), ethyl cellosolve (ethoxyethanol), methoxypropylene glycol, dimethoxypropanol, etc. (2) Aprotic polar solvent: (2 -1) Amide type N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide Mido, N-ethylacetamide, N, N-diethylacetamide, hexamethylphosphoric amide, etc. (2-2) Lactones, cyclic amide type γ-butyrolactone, N-methyl-2-pyrrolidone, ethylene carbonate, propylene carbonate Representative examples thereof include isobutylene carbonate and the like (2-3) nitrile-based acetonitrile and the like (2-4) oxide-based dimethyl sulfoxide and the like.

As conventional solutes, the following organic or inorganic acids or salts thereof may be used alone or in combination.

(1) Organic acids: (1-1) Aliphatic monocarboxylic acids Formic acid, acetic acid, propionic acid, enanthic acid, etc. (1-2) Aliphatic dicarboxylic acids Malonic acid, succinic acid, glutaric acid, adipic acid, Methylmalonic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, citraconic acid, itaconic acid, etc. (1-3) Aromatic carboxylic acids Benzoic acid, phthalic acid, salicylic acid, toluic acid, pyromellito Acid, etc. (2) Inorganic acid: boric acid, phosphoric acid, silicic acid, HBF ₄ , HPF _6, etc. (3) Ammonium: (3-1) Ammonium (3-2) Monoalkylammoniums Methylammonium, ethylammonium, propyl Ammonium, etc. (3-3) Dialkylammoniums Dimethylammonium, Diethylammonium Ethylmethylammonium, dibutylammonium, etc. (3-4) Trialkylammoniums, trimethylammonium, triethylammonium, tributylammonium, etc. (3-5) Quaternary ammoniums, tetramethylammonium, triethylmethylammonium, tributylmethylammonium, tetraethylammonium, etc. N, N-dimethylpyrrolidinium, N, N-methylethylpyrrolidinium, etc. (4) Others: phosphonium and arsonium

[0016]

The trioxyethylene diglycolic acid or its salt used in the present invention remarkably improves the withstand voltage property of the electrolytic capacitor which can be used at high voltage. It is considered that there exists a mechanism that an appropriate micelle layer is formed at the interface of the aluminum oxide film which is a dielectric.

[0017]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples.

Example 1 and Comparative Example 1 1) Preparation of Electrolyte Solution As Comparative Example 1, an electrolyte solution having the following composition conventionally used was prepared by a conventional method and used. Ammonia gas was introduced into the electrolytic solution by inserting a pH measuring electrode, and was blown in with stirring until the pH reached about 5.5.

Electrolytic solution composition of Comparative Example 1 Component weight (g) Ethylene glycol 90 1,3-butanediol 10 Boric acid 20 Mannitol 5 1,6-decanedicarboxylic acid 5 Polyoxyethylene 1 Trimethylolpropane Ammonia gas

The conductivity (30 ° C.) of this electrolyte sample was 0.
It was 683 ms / cm.

As Example 1, an electrolytic solution having the following composition, to which the sample of the compound of the present invention was added, was used in place of the conventionally used solute and prepared by a conventional method. Ammonia gas was introduced into the electrolytic solution by inserting a pH measuring electrode, and was blown in with stirring until the pH reached about 5.5.

Electrolyte solution composition of Example 1 Component weight (g) ethylene glycol 90 1,3-butanediol 10 boric acid 20 mannitol 5 trioxyethylene 5 diglycolic acid polyoxyethylene 1 trimethylolpropane ammonia gas

The conductivity (30 ° C.) of this electrolyte sample was 0.
It was 755 ms / cm.

2) Measurement of withstand voltage A device having a rated voltage of 450 V and a rated capacity of 22 μF was impregnated with the above electrolytic solution, and a constant voltage power supply was used to obtain 10 mA DC.
The withstand voltage was measured at. The electric conductivity was measured at 30 ° C. The results of calculating the average value of the measured values of 5 samples are shown below.

[0025]

[Table 1]

The withstand voltage of Example 1 is 1 compared with Comparative Example 1.
It was improved by 5% or more to 600V or more. On the other hand, the electrical conductivity was kept good. It was confirmed that the electrolytic solution composition to which the compound according to the present invention was added has a withstand voltage property capable of withstanding a high voltage of 550 V or higher.

Example 2 and Comparative Example 2 1) Preparation of Electrolyte Solution As Comparative Example 2, an electrolyte solution having the following composition conventionally used was prepared by a conventional method and used. Ammonia gas was introduced into the electrolytic solution by inserting a pH measuring electrode, and was blown in with stirring until the pH reached about 5.5.

Composition of Electrolyte Solution of Comparative Example 2 Component Weight (g) Ethylene glycol 100 Boric acid 15 Mannitol 10 Azelaic acid 5 Polyoxyethylene 1 Trimethylolpropane Ammonia gas

The conductivity (30 ° C.) of this electrolyte sample was 0.
It was 803 ms / cm.

As Example 2, an electrolytic solution having the following composition, to which the sample of the compound according to the present invention was added, was prepared by a conventional method in place of the conventionally used solute. Ammonia gas was introduced into the electrolytic solution by inserting a pH measuring electrode, and was blown in with stirring until the pH reached about 5.5.

Composition of Electrolyte Solution of Example 2 Component Weight (g) Ethylene glycol 85 1,3-butanediol 15 Boric acid 15 Pentaerythritol 5 Trioxyethylene 10 Diglycolic acid Polyoxyethylene 1 Trimethylolpropane Ammonia gas

The conductivity (30 ° C.) of this sample is 0.767.
(Ms / cm).

2) Measurement of withstand voltage An element having a rated voltage of 450 V and a rated capacity of 22 μF was impregnated with the above electrolytic solution, and a constant voltage power source was used to obtain DC of 10 mA.
The withstand voltage was measured at. The electric conductivity was measured at 30 ° C. The results of calculating the average value of the measured values of 5 samples are shown below.

[0034]

[Table 2]

The withstand voltage of Example 2 is 3 compared with Comparative Example 2.
It was improved by 3% or more and was 600 V or more. On the other hand, the electrical conductivity was kept good. It was confirmed that the electrolytic solution composition to which the compound according to the present invention was added has a withstand voltage property capable of withstanding a high voltage of 550 V or higher.

[0036]

According to the electrolytic solution for an electrolytic capacitor of the present invention, by adding trioxyethylenediglycolic acid or a salt thereof as a solute to a solvent containing an organic polar solvent as a main solvent, a voltage of 550 V or higher can be obtained. An electrolytic capacitor electrolytic solution having a high withstand voltage that can be used under high voltage is obtained, and its industrial value is high.

Claims (1)

[Claims] 1. A compound represented by the general formula: An electrolytic solution for an electrolytic capacitor, which comprises adding trioxyethylene diglycolic acid or a salt thereof as a solute.