JPH01152614A - 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 adding phosphoric acid or the salt with 7-methyl-1, 14- tetradecanedicarboxylic acid or the salt being a main dissolved substance. CONSTITUTION:An electrolyte obtained by putting 7-methyl-1, 14- tetradecanedicarboxylic acid, and the mixture of those salts into dissolution in ethylene glycol and by adding phosphoric acid or the salt can allow specific resistance to be reduced and the tangent of loss angle to be suppressed. It is desirable that the amount of 7-methyl-1 and 14-tetradecanedicarboxylic acid ranges 8-30wt.% and the added amount of phosphoric acid or the salt 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.
The present invention 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
The esterification reaction between ethylene glycol and boric acid progresses due to heating, and water is produced at this time, and this water reacts with the aluminum foil, which is the material of the capacitor in the electrolytic capacitor, and dissolves it. Furthermore, because hydrogen gas is generated and the internal pressure of the capacitor increases, electrolytic capacitors using this electrolyte cannot 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, electrolytic capacitors for high temperatures do not use ethylene glycol/Nisderian borate electrolytes, but instead use organic acid electrolytes containing organic acids or their salts with relatively high molecular weight as solutes. and is being considered.

1.6-decanedicarboxylic acid (Japanese Patent Publication No. 13293/1983 Electrolytic Capacitor Driving Electrolyte J) is known as a solute in acid-based electrolytes for medium and high voltage applications.
- Electrolytic capacitors using an electrolyte 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. ,
An extreme decrease in capacitance "t" and a significant increase in leakage current were observed, and the demand for an electrolytic capacitor with higher performance 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 phosphoric acid or its salt, the above-mentioned drawbacks can be removed, and the specific resistance of the electrolyte 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.

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

Next, an 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 phosphoric acid or its salt is added, together with a conventional example. Shown in Table 1. 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 using the electrolytes of "Conventional Example 2" and "Example 2" and Example 2 (
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. (Each value of the initial and post-test characteristics is the average value of each 20 electrolytic capacitors.) Table 3 Comparison of characteristics (400V-10uF) [Effects of the invention] As can be seen from Tables 2 and 3, in Conventional Example 2, the initial capacitance 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 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 phosphoric acid or its salt, the resistivity can be lowered and the tangent of the loss angle can be suppressed. be able to.

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 amount of solute in 14-tetradecanedicarboxylic acid is 8 to 3
A range of 0 wt% is preferable, and if it is less than 8 wt%, the specific resistance will increase, and if it exceeds 30 wt%, the spark voltage of the electrolyte will decrease, so neither can be put to practical use.

In addition, the amount of phosphoric acid or its salt added is 0.05 to 3wt.
% range is preferable; if it is less than 0.05 wt%, the addition effect will be small, and if it exceeds 3 wt%, the spark voltage of the electrolyte will decrease, so neither 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 phosphoric acid or a salt thereof is added.