JPS61294809A - Electrolytic liquid for driving electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrolytic solution for driving an electrolytic capacitor,
By significantly lowering the specific resistance of the electrolyte, the loss angle tangent and high frequency characteristics of electrolytic capacitors are improved.
Furthermore, the present invention provides an electrolytic capacitor that can be used at high temperatures, has a long life, and is highly reliable, in which changes in capacitance and increases in leakage current can be suppressed.

[Prior Art and Problems] Conventionally, so-called ethylene glycol/boric acid ester-based electrolytes have been used as electrolytes for driving aluminum electrolytic capacitors, particularly for medium and high voltages. This type of electrolyte is
Heating progresses the esterification reaction between ethylene glycol and boric acid, which produces water, which increases the internal pressure of the capacitor in the electrolytic capacitor. It could not be used for temperature purposes. In addition, in order to solve the above-mentioned problem, an electrolytic solution of the same type that promotes esterification and removes the produced water has been proposed, but although the reaction with water is suppressed, the viscosity of the electrolytic solution increases. , the specific resistance became significantly high, and in electrolytic capacitors using this electrolyte, the loss angle tangent and impedance at high frequencies increased significantly, making it impossible to meet the demands for high characteristics. For these reasons, electrolytic capacitors for high temperatures do not use ethylene glycol/boric acid ester electrolytes, but rather organic acid electrolytes containing relatively large molecular weight organic acids or their salts as solutes. It is being considered.

1.6-decanedicarboxylic acid (Japanese Patent Publication No. 13293/1983 Electrolyte for Driving Electrolytic Capacitors 1) is known as a solute in organic acid-based electrolytes for medium and high pressures.
Electrolytic capacitors using electrolytes containing decanedicarboxylic acid show an extreme decrease in capacitance and a significant increase in leakage current due to the solute itself, high temperature load tests, and high temperature no-load tests. The request could not be met.

[Improvements and Summary of the Invention] However, the present invention eliminates the above-mentioned drawbacks, and specifically, the present invention is intended to eliminate the above-mentioned drawbacks, and specifically, the present invention is an attempt to eliminate the above-mentioned drawbacks.
- By using a mixture of decanedicarboxylic acid or a mixture of their salts as a solute, complex formation between 1,6-decanedicarboxylic acid and aluminum foil is prevented, resulting in changes in capacitance and increase in leakage current of electrolytic capacitors. The objective is to provide electrolytic capacitors with higher performance and reliability by suppressing the loss angle, lowering the specific resistance of the electrolytic solution, and reducing the tangent of the loss angle and the impedance at high frequencies.

[Example] Next, the above-mentioned 1.6-decanedicarboxylic acid and 1.10-
Examples of the electrolytic solution according to the present invention in which a mixture of decane dicarboxylic acids or a mixture of their salts are dissolved in ethylene glycol are shown in Table 1 together with conventional examples. The electrolyte composition is w
t% and specific resistance (Ω·cm) are at a liquid temperature of 20°C. Also.

The spark voltage is at 85°C.

Table 1, Examples of Electrolyte Composition Next, among the electrolytes shown in Table 1, electrolytic capacitors using the electrolytes of Conventional Example 2, Example 1, and Example 3 (
Temperature 1 for each 20 pieces with a rating of 400V/10μF)
High temperature no-load test (105℃, rated voltage applied 10μF).

1000 hours) are shown in Table 3. (Each characteristic in the initial field and after the test is the average value of each 20 electrolytic capacitors.) Table 2 Xie Mu W (400110μF) [Effect of the invention] As can be seen from Tables 2 and 3, the conventional example 2, the initial capacitance is about 10% of the rated value, and the leakage current is 3.
It has increased more than 0 times.

The phenomenon shown in the conventional example shown in Tables 2 and 3 is caused by the reaction of 1,6-decanedicarboxylic acid in the driving electrolyte with the aluminum foil forming the capacitor element, which reduces the surface area of the capacitor element. This results in a significant decrease in capacitance, which is proportional to the surface area, and an increase in leakage current due to the unstable reaction of 1,6-decanedicarboxylic acid with the dielectric aluminum anodic oxide film. An aluminum complex film is formed, which dissolves in the driving electrolyte at high temperatures, resulting in an increase in leakage current.

On the other hand, the present invention suppresses the complex formation of 1,6-decanedicarboxylic acid by using 1,10-decanedicarboxylic acid or its salt as a solute together with 1,6-decanedicarboxylic acid or its salt. This phenomenon can be prevented. Further, by lowering the specific resistance, the tangent of the loss angle and the impedance at high frequencies can be suppressed.

Next, regarding the effect on product properties caused by suppressing complex formation by mixing 1.10-decanedicarboxylic acid or its salt, for example, 1. Figure 1 shows the behavior when 10-decanedicarboxylic acid is added, taking as an example the change in the initial capacitance ratio to the rated capacitance. Figure 2 shows the changes in current value. The electrolytic capacitors used here all have a rating of 400 V and 10 μF, and the multi-value is the average value of 20 capacitors.

As can be seen from FIG. 1, when the concentration of 1,10-decanedicarboxylic acid added is low, the initial capacitance value is low. 0.5
Addition of 1 wt% produces a sufficient effect, although the effect is small when added by wt%. Therefore, it is preferable to add 1 wt% or more of -F. As shown in Figure 2, the effect is small when added at 0.5 wt%, but the effect becomes sufficiently clear when added at 1 wt%.

Therefore, by using the driving electrolyte according to the present invention, it is possible to provide an electrolytic capacitor with higher performance and higher reliability.

[Scope of practical application of the invention] In the components of the electrolytic solution according to the present invention, the amount of the mixed solute of 1.6-decanedicarboxylic acid and 1.10-decanedicarboxylic acid is in the range of 8 wt% to 30 wt%. is preferable, and 8
If it is less than 30 wt%, the specific resistance becomes large, and conversely, 30 w
If it exceeds t%, the spark voltage of the electrolyte decreases, so that none of them can be put to practical use.

[Brief explanation of drawings]

Figure 1 shows 1,10 for 1,6-decanedicarboxylic acid.
- A characteristic diagram showing the relationship between the concentration of decanedicarboxylic acid added and the ratio between the initial capacitance and the rated capacitance of an electrolytic capacitor,
Figure 2 shows 1,10 for 1,6-decanedicarboxylic acid.
- It is a characteristic diagram showing the relationship between the additive concentration of decanedicarboxylic acid and the leakage current of an electrolytic capacitor.

Claims (1)

[Claims] An electrolytic solution for driving an electrolytic capacitor, characterized in that a mixture of 1,6-decanedicarboxylic acid and 1,10-decanedicarboxylic acid or a mixture of their salts is used as a main solute, and ethylene glycol is used as a solvent.