JPH09115782A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the characteristics and reliability of an electrolytic capaci tor at a low cost by adding dimethylglyoxime to an electrolyte prepared by dissolving at least adipic acid or benzoic acid in a solvent prepared by mixing ethylene glycol with water. SOLUTION: An electrolyte for driving electrolytic capacitor is obtained by adding 0.01-3.0wt.% dimethylglyoxime to a solution prepared by dissolving at least one kind of organic carboxylic acid composed of adipic acid or benzoic acid or the salt of the acid in a solvent prepared by mixing ethylene glycol with 10-30wt.% water. Consequently, the occurrence of a gas can be suppressed, because the hydration between the water in the electrolyte and electrode foil at a high temperature is suppressed even when the adding amount of the water increases. Therefore, an electrolyte which has excellent electrical conductivity and is stable at a high temperature can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an electrolytic solution for driving an electrolytic capacitor (hereinafter simply referred to as an electrolytic solution), and to an electrolytic solution having excellent electric conductivity and stable at high temperature. is there.

[0002]

2. Description of the Related Art Generally, an electrolytic capacitor comprises an anode foil obtained by etching a high-purity aluminum foil to increase its surface area and anodizing the surface to make it a dielectric, and an etched cathode foil facing the anode foil. An element having a structure in which a separator is wound between them is impregnated with an electrolytic solution, housed in a case, and sealed with a sealing body. In such an electrolytic capacitor, the characteristics of the electrolytic solution are a major factor in determining the performance of the electrolytic capacitor. In particular, with the recent miniaturization of electrolytic capacitors, those with a high etching rate have come to be used, and the resistivity of capacitors has increased. Therefore, the electrolytic solution used for this must always have a low specific resistance. Required. Among the conventional electrolytes, the one with low cost and low specific resistance is ethylene glycol as the main solvent, water is added to this, and further ammonium salts of carboxylic acids such as adipic acid and benzoic acid are dissolved as electrolytes. Things are being used.

[0003]

However, although such an electrolytic solution can reduce the specific resistance, since the amount of water added is large, the water in the electrolytic solution undergoes a hydration reaction with the electrode foil at high temperatures. As a result, gas is generated and the internal pressure of the electrolytic capacitor rises, so it was difficult to use at 105 ° C or higher.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises ethylene glycol and 10 to 30 wt. %
Dimethylglyoxime is added to a solvent prepared by dissolving at least one kind of organic carboxylic acid or its salt among adipic acid and benzoic acid as a solute in a solvent mixed with water.
~ 3.0 wt. %.

[0005]

[Function] Even if the amount of water added is increased by adding dimethylglyoxime, the hydration reaction between water in the electrolytic solution and the electrode foil at a high temperature of 105 ° C. is suppressed, and gas generation is suppressed.

As a result of various studies on the amount of dimethylglyoxime added, 0.01 to 3.0 wt. It was good within the range of%. 0.01 wt. If it is less than%, the suppressing effect does not appear,
3.0 wt. If it exceeds%, it will precipitate.

The amount of water added is 10 to 30 wt. %, 10 wt. If it is less than%, the specific resistance does not decrease and it is 3
0 wt. If it exceeds%, the above effect due to dimethylglyoxime will not be exhibited.

Embodiments of the present invention will be described below. Table 1 shows the electrolytic solution according to the present invention (sample symbols a, b, c, d,
e, f, g, h, i, j) and the composition ratio of each of the conventional electrolytic solutions (sample symbols A, B, C, D) for comparison, and the specific resistance of the electrolytic solutions at 30 ° C. Indicates.

[0008]

[Table 1]

Further, in Table 2, 50 electrolytic aluminum capacitors were prepared by using each of the above electrolytic solutions, and the aluminum electrolytic capacitors were heated to 105 ° C.
The results of the 1000 hour load test are shown below. All capacitor samples are aluminum electrolytic capacitors rated at 10V and 4700 μF.

[0010]

[Table 2]

Conventional electrolytic solution (sample symbols A, B, C, D)
The aluminum electrolytic capacitor that used was generated a lot of gas, and the explosion-proof valve was activated in a short time. Electrolyte solution according to the present invention (sample symbols a, b, c, d, e, f, g, h,
Aluminum electrolytic capacitors using i, j) are
It shows stable characteristics even after 1000 hours at 05 ° C.

[0012]

As described above, in the present invention, by adding dimethylglyoxime, an electrolyte having excellent stability at high temperature and low specific resistance can be obtained even if the amount of water added increases. In addition, it is possible to improve the characteristics and reliability of the electrolytic capacitor at low cost, which is of great industrial and practical value.

Claims (3)

[Claims] 1. An organic carboxylic acid of at least one of adipic acid and benzoic acid or a salt thereof is dissolved as a solute in a solvent mixture of ethylene glycol and water, and dimethylglyoxime is added thereto. Characteristic electrolytic solution for driving electrolytic capacitors. 2. The amount of dimethylglyoxime added is
0.01-3.0 wt. %, The electrolytic solution for driving the electrolytic capacitor according to claim 1. 3. The amount of water added is 10 to 30 wt. %
The electrolytic solution for driving the electrolytic capacitor according to claim 1 or 2.