JP2002217066A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the electrolyte for driving an aluminum electrolytic capacitor having low specific resistance, and improved reliability at a high temperature. SOLUTION: At least one kind of dissolved substance out of adipic acid, benzoic acid, and their salt, and 8-hydroxyquinaldine or dihydroquinaldine having a hydroxyl group at least at 8-position are added, by 0.01-3.0 wt.%, to a solvent where ethyleneglycol is mixed with water.

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 (hereinafter referred to as an electrolytic solution), and more particularly to an electrolytic solution having low specific resistance and improved reliability at high temperatures. is there.

[0002]

2. Description of the Related Art An electrolytic capacitor has a surface area enlarged by etching a high-purity aluminum foil, and a separator is interposed between an anode foil whose surface is anodized and an etched cathode foil facing the anode foil. The element having the structure wound and wound is impregnated with an electrolytic solution, stored 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, electrode foils having a high etching magnification have been used, and tan δ of the capacitors has been increased. Therefore, an electrolytic solution having a low specific resistance has always been required.
Conventionally, as an electrolytic solution having a low cost and a low specific resistance, a solution obtained by adding water to ethylene glycol as a main solvent and further dissolving an ammonium salt such as adipic acid or benzoic acid as a solute has been used.

[0003]

However, in order to meet market demands, it is necessary to further reduce the specific resistance of the electrolyte. To achieve this, it is necessary to increase the solute concentration or add a large amount of water. No. However, when the solute concentration is increased, the solute precipitates, and when a large amount of water is added, the moisture in the electrolyte causes a hydration reaction with the electrode foil at a high temperature to generate gas, thereby increasing the internal pressure of the electrolytic capacitor. Therefore, use at 105 ° C. or more was difficult.

[0004]

In order to solve the above-mentioned problems, the present invention suppresses the hydration reaction between water and an electrode foil at a high temperature by adding 8-hydroxyquinaldine to an electrolytic solution. An object of the present invention is to provide an electrolytic solution having low specific resistance and excellent reliability at high temperatures. That is, a solvent obtained by mixing ethylene glycol and water is mixed with at least one solute of adipic acid, benzoic acid and a salt thereof, and 8-hydroxyquinaldine (formula 2) or a dihydro acid having a hydroxy group at least at the 8-position. An electrolytic solution for driving an electrolytic capacitor, characterized by adding quinaldine.

[0005]

Embedded image

Further, the amount of the above-mentioned 8-hydroxyquinaldine or dihydroxyquinaldine having a hydroxy group in at least the 8-position is 0.01 to 3.0 wt%, and the electrolytic solution for driving an electrolytic capacitor is characterized in that: It is.

[0007] The mixing amount of the water is 10.0 to 50.
An electrolytic solution for driving an electrolytic capacitor, wherein the electrolytic solution is 0 wt%.

The salts of adipic acid and benzoic acid include ammonium salts, primary amine salts such as methylamine, ethylamine and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine and diethylamine, trimethylamine, and the like. Examples include tertiary amine salts such as diethylmethylamine, ethyldimethylamine, and triethylamine, and quaternary ammonium salts such as tetramethylammonium, triethylmethylammonium, and tetraethylammonium.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Since 8-hydroxyquinaldine in an electrolytic solution is adsorbed on the surface of an electrode foil, hydration of water and the electrode foil in the electrolytic solution at a high temperature of 105 ° C. is suppressed, and Even if the addition amount increases, gas generation can be suppressed. Further, since it is not necessary to increase the amount of the solute, the precipitation of the solute and the withstand voltage are not reduced. Also, dihydroxyquinaldine having a hydroxy group at least at the 8-position has the same effect as 8-hydroxyquinaldine.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.
An electrolytic solution was prepared according to the composition shown in Table 1, and the specific resistance at 30 ° C. was measured.

[0011]

[Table 1]

Using the electrolyte shown in Table 1, a rated voltage of 6.3 V-
Ten aluminum electrolytic capacitors each of 6800 μF (φ12.5 × 25 mmL) were prepared, and the capacitance, tan
δ, initial characteristics of leakage current and high temperature load test (105 ° C
Table 2 shows the results obtained by examining the rate of change in capacitance, tan δ, leakage current, and appearance after the rated voltage was applied for 1000 hours.

[0013]

[Table 2]

Conventional Examples 1-2, Comparative Examples 1-3 and Examples 1
In comparison with No. 15, Examples 1 to 13 in which 8-hydroxyquinaldine was added and Examples 14 to 1 in which dihydroquinaldine having a hydroxy group at least at the 8-position were added.
An aluminum electrolytic capacitor using 5 as an electrolyte is 10
Although the characteristics were stable even after 1000 hours at 5 ° C., the explosion-proof valve was operated in a short time in the conventional example.

The amount of 8-hydroxyquinaldine or dihydroxyquinaldine having a hydroxy group at least at the 8-position is preferably in the range of 0.01 to 3.0 wt%. If it is less than 0.01 wt%, the effect of 8-hydroxyquinaldine or dihydroquinaldine cannot be sufficiently obtained,
If it exceeds 3.0 wt%, the capacity change rate and t
An δ deteriorates, which is a problem.

The mixing amount of water added to the electrolyte is 10.0
The range of about 50.0 wt% is preferable. If it is less than 10.0 wt%, the specific resistance of the electrolytic solution will not be reduced, and if it exceeds 50.0 wt%, there is a problem that the effect of 8-hydroxyquinaldine or dihydroquinaldine cannot be sufficiently obtained.

[0017]

As described above, even if a large amount of water is mixed to lower the specific resistance, 8-hydroxyquinaldine or dihydroquinaldine having a hydroxy group at least at the 8-position can be used in the electrolytic solution of the present invention. By the addition, an electrolyte having excellent stability at high temperatures and a low specific resistance can be obtained, so that the characteristics and reliability of the electrolytic capacitor can be improved at low cost.

Claims (3)

[Claims] 1. A solvent in which ethylene glycol and water are mixed, a solute of at least one of adipic acid, benzoic acid and a salt thereof, 8-hydroxyquinaldine (formula 1) or a hydroxy group at at least the 8-position. An electrolytic solution for driving an electrolytic capacitor, comprising dihydroxyquinaldine having the formula: Embedded image 2. An electrolytic capacitor according to claim 1, wherein the amount of 8-hydroxyquinaldine or dihydroquinaldine having a hydroxy group at least at the 8-position is 0.01 to 3.0 wt%. Driving electrolyte. 3. The amount of water according to claim 1 is 10.0
An electrolytic solution for driving an electrolytic capacitor, wherein the amount is 50.0% by weight or less.