JPH01152615A - 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-tetradecanedicarboxylic acid and by adding unsaturated dicarboxylic acid. CONSTITUTION:7-methyl-1, 14-tetradecanedioic carbon acid or the salt are main dissolved substances and an unsaturated diocarboxylic acid consisting of maleic acid, fumaric acid, itaconic acid, or citraconic acid is added. It is desirable that the amount of 7-methyl-1 and 14-tetradecanedioic carbon acid ranges 8-30wt.% and the added amount of unsaturated dicarboxylic acid 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 these reasons, ethylene glycol/boric acid ester-based electrolytes are not used in high-temperature electrolytic capacitors, but 4rR acid-based electrolytes with relatively large molecular weight organic acids or their salts as solutes are used. It is being considered.

1゜6-decanedicarboxylic acid (Japanese Patent Publication No. 13293/1983 ``Electrolytic Solution for Driving Electrolytic Capacitors'') is known as a solute in organic acid-based electrolytes for medium and high pressures.
Electrolytic capacitors using an electrolytic solution containing decanedicarboxylic acid have a low initial capacitance because the solute itself reacts with the aluminum foil that forms the capacitor element and forms a complex, and also has low initial capacitance during high-temperature load tests and high-temperature no-load tests. In,
An extreme decrease in the electrostatic field and a significant increase in leakage current were observed, and the demand for higher performance electrolytic capacitors could not be met.

[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 unsaturated dicarboxylic acid, the above-mentioned drawbacks can be removed, and the specific resistance of the electrolytic solution can be lowered,
By reducing the tangent of the loss angle and the equal series resistance, an electrolytic capacitor with high performance and high reliability is provided.

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

Next, a first example of an 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 unsaturated dicarboxylic acid is added together with a conventional example will be described. Shown in the table. The electrolytic solution composition is wt%, and the specific resistance (Ω·cm) is at a solution temperature of 20°C. Further, the spark voltage was at 85°C.

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. In addition, electrolytic capacitors (rated 400
High temperature no-load test (105℃
.

1000 hours) are shown in Table 3. (The extrusion of the initial and post-test characteristics is the average value of each 20 electrolytic capacitors.) [Effect of the invention] As can be seen from Tables 2 and 3, in Conventional Example 2, the initial capacitance was rated Approximately 10% of the value is quite low, and even after the test, the rate of change is large. Further, as can be seen from Table 3, in Conventional Example 2, the leakage current is 30 times or more.

On the other hand, in the present invention, by using 7-methyl-1,14-tetradecanedicarboxylic acid or its salt as a solute and adding an unsaturated dicarboxylic acid, the resistivity can be lowered and the loss angle can be suppressed tangently. Can be done.

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 of 14-detradecanedicarboxylic acid is 8-30
A range of wt% is preferable; when it is less than 8wt%, the specific resistance becomes large, and conversely, when it exceeds 30wt%, the electrolyte may become flammable.
None of these methods can be put to practical use because the flower voltage increases by F.

In addition, the amount of unsaturated dicarboxylic acid added is 0.05 to 3wt.
% is preferable; if it is less than 0.05 wt %, the effect of addition is small, and if it exceeds 3 wt %, the spark voltage of the electrolyte will drop, so that it cannot be put to practical use.

Claims (1)

[Claims] (1) An electrolytic capacitor characterized in that the main solute is 7-methyl-1,14-tetradecanedicarboxylic acid or a salt thereof, and an unsaturated dicarboxylic acid consisting of maleic acid, fumaric acid, itaconic acid, or citraconic acid is added. Drive electrolyte.