JPH06188152A - Electrolytic solution for driving electronic capacitor and electrolytic capacitor using same - Google Patents

Abstract

PURPOSE:To increase the sparking voltage and the specific conductance of the title solution and to reduce a drop in the specific conductivity when the solution is left at a high temperature by a method wherein a sec. monocarboxylic acid salt whose number of carbon atom is specific is used for an electrolyte. CONSTITUTION:A monocarboxylic acid which is expressed by the chemical formula and which is provided with a sec. carboxyl group having the total number carbon atoms is 9 to 30 is used (in the formula, R1 and R2 represent an alkyl group, a cycloalkyl, an aryl group or a substituent including an unsaturated bond or heteroatoms and both exclude a phenyl group). Thereby, since the total number of carbon atoms can be made large and the sec. carboxyl group is used, a high sparking voltage can be obtained. In addition, the sec. carboxyl group hardly causes an esterification reaction with a solvent, and an electrolytic solution which is stable at a high temperature can be obtained. In addition, the problem of a bad smell such as a carboxylic acid whose number of carbon atoms is small can be solved. Thereby, the sparking voltage, the specific conductance, a drop in the specific conductance of the solution when the solution is left at a high temperature and the problem of the bad smell are improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for driving an electrolytic capacitor and an electrolytic capacitor using the electrolytic solution, and more particularly to an electrolytic solution for driving an electrolytic capacitor for medium and high voltage classes and an electrolytic capacitor using the electrolytic solution.

[0002]

2. Description of the Related Art Conventionally, an ethylene glycol-boric acid type electrolyte has been used as an electrolytic solution for driving a medium- and high-voltage electrolytic capacitor. However, this type of electrolytic solution produces water by the esterification of ethylene glycol and boric acid. To generate 1
At 00 ° C or higher, the vapor pressure was high, and it was apt to react with aluminum as an electrode and was not suitable for use at high temperature. In order to improve such a defect, as a solute, a total carbon number of 4 to
No. 8 primary and secondary monocarboxylic acid (Japanese Patent Publication No. 4-196
91), a quaternary ammonium salt of an aliphatic monocarboxylic acid (JP-A-62-248216), and the like have been proposed.

[0003]

However, in recent years, the spark voltage and the specific conductivity are higher, and the decrease in the specific conductivity when left at high temperature is small, and there is no odor at the time of manufacturing or opening the capacitor. There is a demand for electrolytic solutions and long-life electrolytic capacitors with high reliability.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that if a secondary monocarboxylic acid salt having a specific carbon number is used as an electrolyte, the spark voltage and the specific conductivity are increased. The inventors have found that an electrolytic solution for driving an electrolytic capacitor, which has a high degree of conductivity, a small decrease in specific electric conductivity when left at high temperature, and has no problem of odor and the like, can be obtained, and arrived at the present invention. That is, the present invention is an electrolytic capacitor driving electrolytic solution comprising a secondary monocarboxylic acid salt (A) having a total carbon number of 9 to 30 and ethylene glycol, and an electrolytic capacitor using the electrolytic solution.

[0005]

In general, deterioration of an electrolytic solution using a salt of a carboxylic acid at a high temperature mainly occurs due to an esterification reaction between a solvent and a carboxylic acid. An advantage of the present invention is that it uses a monocarboxylic acid having a secondary carboxyl group having 9 to 30 carbon atoms in total. A high spark voltage can be obtained by making the total carbon number large and using a secondary carboxyl group. And second
The high-grade carboxyl group hardly causes an esterification reaction with a solvent, and a stable electrolyte solution can be obtained at high temperature. Further, the problem of odor such as carboxylic acid having a low carbon number is solved. As a result, an electrolytic solution in which the spark voltage, the specific conductivity, the decrease in the specific conductivity when left at high temperature, and the problem of odor are improved is obtained, and the electrolytic capacitor using the electrolytic capacitor driving electrolytic solution of the present invention is The rate of change of capacity and tan δ is small,
It has a longer life and extremely higher reliability than conventional products. Also, there is no longer any unpleasant odor when manufacturing or opening the condenser.

[0006]

EXAMPLES Examples of the present invention will be described below.

The secondary monocarboxylic acid of the secondary monocarboxylic acid salt (A) having a total carbon number of 9 to 30 in the present invention has a structure of the following formula. In the formula, R1 and R2 are, for example, methyl, ethyl, propyl,
In addition to alkyl groups such as butyl, hexyl, octyl, decyl, and pentadecyl, cycloalkyl groups such as cyclopentyl and cyclohexyl, aryl groups such as phenyl and benzyl, and a substituent containing an unsaturated bond or a hetero atom (provided that R1, R2 is not phenyl group). Examples of secondary monocarboxylic acids having the above structural formula include:
For example, 2-ethylheptanoic acid, 2-methylnonanoic acid, 2
-Propylheptanoic acid, 2-ethyloctanoic acid, 2-butylcaproic acid, 2-ethyldecanoic acid, 2-butylnonanoic acid, 2-methylarachidonic acid, 2-phenylpropionic acid, 2-phenylbutyric acid, 2-phenoxypropionic acid, 2-phenoxybutyric acid, 2-methoxyoctanoic acid, 2
-Butoxycaproic acid, α-phenylcyclopentaneacetic acid, bis- (4-hydroxyphenyl) acetic acid, bis-
(4-methoxyphenyl) acetic acid may be mentioned.

Of these, preferred are 2-ethylheptanoic acid, 2-methylnonanoic acid, 2-ethyloctanoic acid, 2-propylheptanoic acid, 2-ethyldecanoic acid and 2
-Butylnonanoic acid and other alkyl groups.

The total carbon number of the secondary monocarboxylic acid is 9 to 3
0, preferably 9 to 20, more preferably 9 to 13, and particularly preferably 10 to 13. Total carbon number is 3
If it exceeds 0, the solubility in the electrolyte solvent decreases. From the viewpoint of solubility, 9 to 20 is preferable. Further, considering the balance between the spark voltage and the specific electric conductivity, those having a total carbon number of 9 to 13 are preferable, and those having a total carbon number of 10 to 13 are particularly preferable.

As the secondary monocarboxylic acid salt (A),
Examples thereof include ammonium salts, amine salts and quaternary ammonium salts of secondary monocarboxylic acids. As amines constituting the amine salt, primary amines (methylamine, ethylamine, propylamine, butylamine, ethylenediamine, etc.), secondary amines (dimethylamine, diethylamine, dipropylamine, methylethylamine, diphenylamine, etc.), tertiary amines ( Trimethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo (5,4,0) -undecene-7 and the like) can be mentioned. Examples of the quaternary ammonium constituting the quaternary ammonium salt include tetraalkylammonium (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, methyltriethylammonium, dimethyldiethylammonium, etc.), pyridium (1-methylpyridinium). 1-ethylpyridinium, 1,3-diethylpyridinium and the like). Among these, preferred are ammonium salts and amine salts, and particularly preferred are ammonium salts.

The molar ratio of the acid forming the secondary monocarboxylic acid salt (A) to the base is usually 1: 2 to 1: 0.5, preferably 1: 1.2 to 1: 0.8.

In the electrolytic capacitor driving electrolytic solution of the present invention, other solvent can be used together with ethylene glycol as a solvent. Solvents that can be used in combination include polyhydric alcohol solvents (propylene glycol, diethylene glycol, 1,
4-butanediol, glycerin, polyoxyalkylene polyol, etc., lactone solvent (γ-butyrolactone, γ-valerolactone, δ-valerolactone, 3-methyl-1,3-oxazolidin-2-one, 3-ethyl- 1,3-
Oxazolidin-2-one, etc., amide solvents (N-methylformamide, N, N-dimethylformamide, N-methylacetamide, N-methylpyrrolidinone, etc.), ether solvents (methylal, 1,2-dimethoxyethane) 1
-Ethoxy-2-methoxyethane, 1,2-diethoxyethane, etc.), nitrile-based solvents (acetonitrile, 3-methoxypropionitrile, etc.), furan-based solvents (2,5-dimethoxytetrahydrofuran, etc.), 2-imidazolide Examples thereof include nonones (1,3-dimethyl-2-imidazolidinone and the like), pyrrolidones and mixtures thereof. The content of ethylene glycol in the solvent is usually 60% by weight or more, preferably 80% by weight or more, based on the weight of the solvent.

The electrolytic solution for driving the electrolytic capacitor of the present invention may contain water, if necessary. Its content is usually 20% by weight or less, preferably 5% by weight or less, particularly preferably 1% by weight or less, based on the weight of the electrolytic solution.

The content of the secondary monocarboxylic acid salt (A) in the electrolytic capacitor driving electrolytic solution of the present invention is usually 1 to 70% by weight, preferably 5 to 5% by weight based on the weight of the electrolytic solution.
It is 40% by weight.

Various additives can be added to the electrolytic capacitor driving electrolytic solution of the present invention for the purpose of reducing leakage current and absorbing hydrogen gas. Examples of the additives include phosphoric acid derivatives, boric acid derivatives and nitro compounds.

Next, specific examples of the present invention will be described, but the present invention is not limited thereto. Table 1 shows the electrolytic solution compositions of Examples 1 to 5 of the present invention and Conventional Examples 1 and 2. The samples of Examples 1 to 5 had almost no odor problem at the time of adjustment, whereas the samples of Comparative Examples 1 and 2 had an unpleasant odor derived from the acid.

[0017]

[Table 1]

Table 2 shows the spark voltage, the specific electric conductivity (30 ° C) of the electrolytic solutions of Examples 1 to 5 of the present invention and the conventional Examples 1 and 2, and the decrease rate of the specific electric conductivity after 125 ° C x 1000 hours. Is shown.

[0019]

[Table 2]

As is clear from Table 2, Example 1 of the present invention
The electrolytic solutions of Nos. 5 to 5 have a higher spark voltage than the electrolytic solutions of Conventional Examples 1 to 2 and have a good specific electric conductivity of 2 mS / cm or more, and a low specific electric conductivity decrease rate. The balance of is excellent.

Table 3 shows Examples 1 to 1 of the present invention shown in Table 1.
Aluminum electrolytic capacitor using the electrolytic solution of 5 (rating 45
This is a graph showing characteristic changes in a life test of 0 V, 220 μF) at 125 ° C. Since the electrolytic solutions of Conventional Examples 1 and 2 have a low spark voltage, they could not be applied to aluminum electrolytic capacitors having this rated voltage.

[0022]

[Table 3]

As is clear from Table 3, the aluminum electrolytic capacitors using the electrolytic solutions of Examples 1 to 5 of the present invention have small changes in capacitance and changes in tan δ (tangent of loss angle), and have life characteristics. It is a highly reliable aluminum electrolytic capacitor.

[0024]

As described above, the electrolytic solution for driving an electrolytic capacitor of the present invention has a high spark voltage, a good specific electric conductivity, a small decrease in the specific electric conductivity when left at high temperature, and no odor problem. . Therefore, when the electrolytic solution of the present invention is used in a medium-high voltage class electrolytic capacitor, the electrolytic capacitor can have a long life and high reliability, and there is no problem of unpleasant odor during manufacturing or valve opening, and it has an industrial value. It is great.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takaaki Kiyoshi 1 1-11, Hitotsubashi-honmachi, Higashiyama-ku, Kyoto Sanyo Chemical Industry Co., Ltd. Kasei Industry Co., Ltd.

Claims (3)

[Claims] 1. An electrolytic solution for driving an electrolytic capacitor, which comprises a secondary monocarboxylic acid salt (A) having a total carbon number of 9 to 30 and ethylene glycol. 2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the secondary monocarboxylic acid salt (A) is a secondary ammonium monocarboxylic acid having a total carbon number of 9 to 30. 3. An electrolytic capacitor using the electrolytic solution for driving an electrolytic capacitor according to claim 1.