JP2000173867A - Electrolytic solution for driving aluminum electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an electrolytic solution whose resistivity is low and excellent in stability by a method wherein adipic acid and/or benzoic acid or its salt is dissolved into a solvent formed of a mixture of ethylene glycol and water, and diethylene triamine pentaacetic acid represented by a specific formula is added to the them. SOLUTION: Adipic acid and/or benzoic acid or its salt is dissolved into a solvent formed of a mixture of ethylene glycol and water for the formation of an electrolytic solution, and diethylene triamine pentaacetic acid represented by a formula is added to the electrolytic solution. Water molecules are introduced into diethylene triamine pentaacetic acid molecules and bonded, so that water molecules attached to the surface of an electrode foil are lessened, and if an electrolytic solution is increased in water content, water contained in an electrolytic solution is restrained from being hydrated with an electrode foil at a high temperature of 105 deg.C, so that gas is restrained from being generated. At this point, a diethylene triamine pentaacetic acid added to an electrolytic solution amounts to 0.1 to 3.0 wt.%. A water content is 10 to 30 wt.%.

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 aluminum electrolytic capacitor (hereinafter referred to as an electrolytic solution), and more particularly to an electrolytic solution having excellent conductivity and stable at a high temperature.

[0002]

2. Description of the Related Art Generally, an electrolytic capacitor has a surface area increased by etching a high-purity aluminum foil, and a separator paper is interposed between an anode foil having its surface formed and an etched cathode foil facing the anode foil. An element having a structure wound and wound is impregnated with an electrolytic solution, the element is 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 having a high etching ratio have been used and the resistivity of the capacitors has increased. Required. Among the conventional electrolytes, the ones with low cost and low specific resistance are those in which ethylene glycol is used as the main solvent and water is added to this, and ammonium salts of carboxylic acids such as adipic acid and benzoic acid are dissolved as the electrolyte. It is used.

[0003]

However, when the amount of water added to the electrolytic solution is increased, the specific resistance can be reduced.
At high temperatures, water in the electrolytic solution causes a hydration reaction with the electrode foil to generate gas and raises the internal pressure of the electrolytic capacitor, so that use at 105 ° C. or higher was difficult.

[0004]

The present invention solves the above-mentioned problem by adding diethylenetriaminepentaacetic acid shown in Chemical formula 2 to an electrolytic solution to form a hydration reaction between water in the electrolytic solution and the electrode foil. To provide an electrolyte solution having a low specific resistance and being stable even at a high temperature. That is, the electrolytic solution is characterized by dissolving adipic acid and / or benzoic acid or a salt thereof in a solvent in which ethylene glycol and water are mixed, and adding diethylenetriaminepentaacetic acid shown in Chemical formula 2 below. An electrolyte is characterized in that the amount of the diethylenetriaminepentaacetic acid added is 0.1 to 3.0 wt%. In addition, the amount of water added is 10
It is an electrolyte solution of 30 wt%.

[0005]

Embedded image

[0006]

DETAILED DESCRIPTION OF THE INVENTION Diethylenetriaminepentaacetic acid is added to an electrolyte containing water. Water molecules are incorporated into and bonded to the molecules of diethylenetriaminepentaacetic acid, which reduces the amount of water molecules adhering to the electrode foil surface. The hydration reaction between water in the liquid and the electrode foil is suppressed, and gas generation is suppressed.

As a result of various studies on the amount of diethylenetriaminepentaacetic acid added, it was found that the addition amount was good within the range of 0.1 to 3.0 wt%. If the content is less than 0.1 wt%, no suppression effect is exhibited, and if it exceeds 3.0 wt%, the breakdown voltage is reduced.

[0008] The amount of water added is in the range of 10 to 30 wt%.
%, The above effect due to diethylenetriaminepentaacetic acid is lost.

[0009]

Embodiments of the present invention will be described below. Table 1 shows the composition of each of the electrolytes of Examples 1 to 18 according to the present invention and the electrolytes of Conventional Examples 1 to 6 and 30 ° C. for comparison.
5 shows the results of comparison of the specific resistances of the samples.

[0010]

[Table 1]

[0011] In addition, using the above-mentioned electrolyte, a rated voltage of 10 V-
Fifty aluminum electrolytic capacitors each having a capacity of 4700 μF were produced and subjected to a load test at 105 ° C. for 1000 hours. The results shown in Table 2 were obtained.

[0012]

[Table 2]

As shown in Table 2, the aluminum electrolytic capacitor using the conventional electrolytic solution (conventional examples 1 to 6) generates a large amount of gas and the explosion-proof valve operates in a short time. The aluminum electrolytic capacitors using Examples 1 to 18) did not operate the explosion-proof valve even after 1000 hours at 105 ° C., and showed stable electric characteristics.

[0014]

As described above, in the present invention, by adding diethylenetriaminepentaacetic acid, an electrolytic solution having excellent stability at high temperatures and low specific resistance can be obtained even when the amount of water added is large. Therefore, the improvement of the characteristics and the reliability of the aluminum electrolytic capacitor can be realized at low cost, which is of great industrial and practical value.

Claims (3)

[Claims] An aluminum electrolytic capacitor drive characterized in that adipic acid and / or benzoic acid or a salt thereof is dissolved in a solvent in which ethylene glycol and water are mixed, and diethylenetriaminepentaacetic acid shown in Chemical formula 1 is added. Electrolyte. Embedded image 2. The electrolytic solution for driving an aluminum electrolytic capacitor according to claim 1, wherein the amount of said diethylenetriaminepentaacetic acid added is 0.1 to 3.0 wt%. 3. The electrolytic solution for driving an aluminum electrolytic capacitor according to claim 1, wherein the amount of said water added is 10 to 30 wt%.