JPH05308036A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain an electrolyte for electrolytic capacitors which can stabilize the life characteristic of an electrolytic capacitor for a long period even in a high-temperature atmosphere. CONSTITUTION:The title electrolyte is prepared by adding 1,3-butanediol carboxymethylether expressed by the formula (where, R<1> and R<2> represent hydrogen or carboxymethyl groups, with at least one of them representing a carboxymethyl group) as a solvent composed mainly of an organic polar solvent. The 1,3-butanediol carboxymethylether and its salt can be used at the same time or independently. The ammonium salt of the 1,3-butanediol carboxymethylether is the most suitable for the salt to be used. The optimum adding rate of the solute is about 1-30wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in electrolytic solutions for electrolytic capacitors, and more particularly to adding a carboxymethyl ether compound derived from 1,3-butanediol or a salt thereof to the electrolytic solution for electrolytic capacitors. The present invention relates to an electrolytic solution for an electrolytic capacitor, which realizes long-term stability of life characteristics at high temperature.

[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, benzoic acid, azelaic acid, sebacic acid, decanedicarboxylic acid or salts thereof have been widely used as solutes in electrolytic solutions for medium and high voltage electrolytic capacitors.

[0004]

However, in these known techniques, the long-term stabilization of the life characteristics of the electrolytic capacitor at high temperature is not achieved at present.

Therefore, an object of the present invention is to provide an electrolytic solution for an electrolytic capacitor which realizes long-term stabilization of life characteristics at high temperatures.

[0006]

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 1,3-butanediol carboxymethyl ether or a salt thereof as a solute, It has been found that long-term stabilization of storage characteristics can be realized.

That is, the electrolytic solution for an electrolytic capacitor according to the present invention has the general formula:

[0008]

[Chemical 2]

(Wherein R ¹ and R ² represent a hydrogen atom or a carboxymethyl group, at least one of which represents a carboxymethyl group), and 1,3-butanediol carboxymethyl ether or a salt thereof is added as a solute. It is characterized by doing.

In the present invention, both 1,3-butanediol carboxymethyl ether and its salt can be used at the same time, or each can be used alone.

The ammonium salt is preferably used as the salt.

The amount of 1,3-butanediol carboxymethyl ether or its salt used is preferably about 1% by weight to about 30% by weight with respect to the electrolytic solution for electrolytic capacitors.

When 1,3-butanediol carboxymethyl ether or its salt is added to the electrolytic solution for electrolytic capacitors, the long-term stability of the life characteristics of electrolytic capacitors at high temperatures is improved by about 50% as compared with conventional solutes. To do.

As the organic polar solvent, a solvent mainly composed of protic polar solvent glycols is generally used, but an aprotic polar solvent may 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 include (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 , H
PF ₆ etc. (3) Ammonium: (3-1) Ammonium (3-2) Monoalkylammonium methylammonium, ethylammonium, propylammonium, etc. (3-3) Dialkylammonium dimethylammonium, diethylammonium, ethylmethylammonium, Dibutylammonium, etc. (3-4) Trialkylammoniums, trimethylammonium, triethylammonium, tributylammonium, etc. (3-5) Quaternary ammoniums, tetramethylammonium, triethylmethylammonium, tributylmethylammonium, tetraethylammonium, N, N- Dimethylpyrrolidinium, N, N
-Methylethylpyrrolidinium, etc. (4) Others: phosphonium and arsonium

[0017]

The 1,3-butanediol carboxymethyl ether or its salt used in the present invention stabilizes the life characteristics of the electrolytic capacitor at high temperature for a long period of time. 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 the body.

[0018]

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples.

In preparing the compound sample according to the present invention, 1,3-butanediol dicarboxymethyl ether or its ammonium salt was selected as a specific example of 1,3-butanediol carboxymethyl ether or its salt.

Example 1 and Comparative Example 1 As Comparative Example 1, an electrolytic solution having the following composition which has been conventionally used was prepared by a conventional method and used. The conductivity of this sample was 1.51 (ms / cm).

Electrolyte composition of Comparative Example 1 Component parts by weight Ethylene glycol 90 1,6-decanedicarboxylic acid 8.5 diammonium salt 1,6-decanedicarboxylic acid 1.5 boric acid 3 mannitol 1 polyvinyl alcohol 2 isostearine Acid 1 Polyoxyethyleneglyceryl As Example 1, an electrolytic solution having the following composition was prepared by adding a compound sample according to the present invention in place of the conventionally used solute, and used. The conductivity of this sample was 1.68 (ms / cm).

Electrolyte solution composition of Example 1 Component parts by weight Ethylene glycol 85 1,3-butanediol 13 Dicarboxymethyl ether diammonium salt 1,3-butanediol 2.0 Dicarboxymethyl ether boric acid 2 Mannit 1 Polyvinyl alcohol 1.5 Isostearate 1 Polyoxyethylene glyceryl An electrolytic capacitor was prepared by a conventional method using the above electrolytic solution composition. Rating: 315V, 22μF. This electrolytic capacitor 5 sample was applied at 315V, and the temperature was 130 ° C.
The product was stored for 3000 hours and the product life characteristics were examined.

For this preserved sample, the tangent of capacitance and loss angle was measured as the product life characteristics. The measuring method was a conventional method. Table 1 shows the result of calculating the average value of the measured values of five samples of the storage-treated electrolytic capacitor.

[0024]

[Table 1]

Compared with Comparative Example 1, Example 1 showed a decrease in capacitance change rate of 55.8% and an improvement of 32.0% in the tangent of the loss angle. It was confirmed that the electrolytic capacitor using the electrolytic solution composition containing the compound according to (1) has stability for a long time at high temperature.

Example 2 and Comparative Example 2 As Comparative Example 2, an electrolytic solution having the following composition which has been conventionally used was prepared by a conventional method and used. The conductivity of this sample was 1.52 (ms / cm).

Electrolyte solution composition of Comparative Example 2 Component parts by weight Ethylene glycol 90 Diammonium sebacate 8.5 Sebacic acid 1.5 Boric acid 2 Mannitol 3 Polyvinyl alcohol 2.5 Conventionally used as Example 2. Instead of the solute present, an electrolytic solution having the following composition, to which the compound sample according to the present invention was added, was prepared by a conventional method and used. The conductivity of this sample was 1.65 s / cm).

Electrolyte solution composition of Example 2 Component weight ratio Ethylene glycol 85 1,3-butanediol 11 Dicarboxymethyl ether diammonium salt 1,3-butanediol 4 Monocarboxymethyl ether boric acid 3 Mannitol 2 Polyvinyl alcohol 2 An electrolytic capacitor was prepared by a conventional method using the above electrolytic solution composition. Rating: 315V, 22μF. This electrolytic capacitor 5 sample was applied at 315V, and the temperature was 130 ° C.
The product was stored for 3000 hours and the product life characteristics were examined.

For this preserved sample, the tangent of capacitance and loss angle were measured as product life characteristics. The measuring method was a conventional method. Table 2 shows the result of calculating the average value of the measured values of five samples of the storage-treated electrolytic capacitor.

[0030]

[Table 2]

Compared with Comparative Example 2, Example 2 showed a decrease of 63.0% in the capacitance change rate, and an improvement of 37.8% in the tangent of the loss angle. It was confirmed that the electrolytic capacitor using the electrolytic solution composition containing the compound according to (1) has stability for a long time at high temperature.

[0032]

According to the electrolytic solution for an electrolytic capacitor of the present invention, it is possible to use an electrolytic solution containing an organic polar solvent as a main solvent.
By adding butanediol carboxymethyl ether or salt as a solute, the life characteristics at high temperature of the electrolytic capacitor are significantly stabilized over a long period of time.
Its industrial value is high.

Claims (1)

[Claims] 1. A compound represented by the general formula: (Wherein R ¹ and R ² represent a hydrogen atom or a carboxymethyl group, at least one of which is a carboxymethyl group.) 1,3-butanediol carboxymethyl ether or a salt thereof is added as a solute. Characteristic electrolytic solution for electrolytic capacitors.