JPH01152616A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To reduce specific resistance of electrolyte remarkably, to improve tangent of loss angle and high-frequency characteristics of an electrolytic capacitor, and to obtain an electrolytic capacitor with improved reliability at high temperature by using 7-methyl-1, 14-tetradecanedicarbocxylic acid and by adding oxyacid. CONSTITUTION:7-methyl-1, 14-tetradecanedioic carbon acid or the salt are main dissolved substances and an oxyacid consisting of citric acid, tartaric acid, malic acid, or salicylic acid is added. It is desirable that the amount of 7-methyl-1 and 14-tetradecanedioic carbon acid ranges from 8 to 30wt.% and the added amount of oxyacid ranges 0.05-3wt.%.

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.
This provides an electrolytic capacitor that is highly reliable at high temperatures.

[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, and at this time water is produced.This water reacts with the aluminum foil, which is the material of the capacitor element in the electrolytic capacitor, and dissolves it, and also produces hydrogen gas. electrolytic capacitors using this electrolyte could not be used for higher 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 this reason, ethylene glycol/boric acid ester electrolytes are not used in high-temperature electrolytic capacitors; Organic acid-based electrolytes containing 11 large organic acids or their salts as solutes have been used and studied.

l as a solute in organic acid-based electrolytes for medium and high pressures.

6-decanedicarboxylic acid (Special Publication No. 60-13293r)
Electrolytic solution J) for driving electrolytic capacitors is known, but electrolytic capacitors using this electrolytic solution containing 1,6-decanedicarboxylic acid react with the solute itself or the aluminum foil forming the capacitor element to form a complex. The initial electrostatic field ri1 is low, and in high-temperature load tests and high-temperature no-load tests, a drastic decrease in static electricity and a significant increase in leakage current were observed, and the demand for higher performance electrolytic capacitors cannot be met. It was something that didn't exist.

[Improvements and Summary of the Invention] However, the present invention uses 7-methyl-1, 7-methyl-1,
By using 14-tetradecanedicarboxylic acid and adding an oxyacid, the above-mentioned drawbacks can be removed, and the specific resistance of the electrolytic solution can be lowered to reduce the tangent of the loss angle and the equal series resistance. This provides a high performance and highly reliable electrolytic capacitor.

The structural formula of 7-methyl-1,14-tetradecanedicarboxylic acid is as follows.

Next, examples of the electrolytic solution according to the present invention in which a mixture of 7-methyl-1,14-tetradecanedicarboxylic acid and its salts is dissolved in ethylene glycol and an oxyacid is added are shown in Table 1 along with conventional examples. show. Electrolyte composition is wt%
, specific resistance (Ωcm) is at a liquid temperature of 20°C. Further, the spark voltage was at 85°C.

Table 1 Example of electrolyte composition Next, among the electrolytes shown in Table 1, electrolytic capacitors (
Temperature 1 for each 20 pieces with a rating of 400V/10μF)
Table 2 shows the results of a high temperature load test at 05°C and 1000 hours of rated voltage application. Also,? "Solution capacitor (constant g4o
High temperature no-load test (105
℃.

1000 hours) are shown in Table 3. (The initial and post-test characteristic values are for each 20 electrolytic capacitors.)
P] Average value. ) [Effects of the Invention] As can be seen from Tables 2 and 3a, in Conventional Example 2, the initial electrostatic charge was about 10% lower than the rated value, and the rate of change was large even after the test. Further, as can be seen from Table 3, in Conventional Example 2, the leakage current is 30 times higher.

On the other hand, in the present invention, the specific resistance can be lowered by using 7-methyl-1,14-tetradecanedicarboxylic acid or its salt as a solute and adding an oxyacid.
The tangent of Ml loss angle can be suppressed.

Therefore, by using the driving electrolyte according to the present invention, a capacitor with higher performance and higher reliability can be provided.

[Scope of practical application of the invention] In the components of the electrolytic solution according to the present invention, 7-methyl-1,
The solute stars of 14-tetradecanedicarboxylic acid are 8 to 30.
A range of 8 wt % without grooves increases the specific resistance, and conversely, if it exceeds 30 wt %, the spark voltage of the electrolyte decreases, so that neither can be put to practical use.

Further, the addition M of oxyacid is preferably in the range of 0.05 to 3 wt%, and if it is less than 0.05 wt%, the addition effect is small;
If it exceeds 3 wt%, the spark voltage of the electrolytic solution decreases, so that none of them can be put to practical use.

Claims (1)

[Claims] (1) An electrolytic solution for driving an electrolytic capacitor, characterized in that the main solute is 7-methyl-1,14-tetradecanedicarboxylic acid or a salt thereof, and an oxyacid consisting of citric acid, tartaric acid, malic acid, or salicylic acid is added.