JPH01137617A - Electrolytic capacitor driving electrolyte - Google Patents

Abstract

PURPOSE:To reduce the specific resistivity of electrolyte and reduce tangent of a loss angle and an equivalent series resistance by a method wherein 8,11- dimethyl-1,18-octadecan dicarboxylic acid is employed as the main solute of the electrolyte and phosphoric acid or its salt is added to it. CONSTITUTION:8,11-dimethyl-1,18-octadecan dicarboxylic acid A or its salt is employed as the main solute of electrolyte. Phosphoric acid or its salt is added to the main solute. The constitutional formula of the carboxylic acid A is the formula I. With this constitution, the specific resistivity of the electrolyte can be reduced and tangent of a loss angle and an equivalent series resistance can be reduced.

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 is In electrolytic capacitors using this electrolyte, the loss angle tangent and impedance at high frequencies significantly increased, making it impossible to meet the demands for high characteristics. For this reason, electrolytic capacitors for high temperatures do not use ethylene glycol/boric acid ester electrolytes, but instead use peroxide-based electrolytes that contain relatively large molecular weight organic acids or their salts as solutes. and is being considered.

As a solute of an organic acid-based electrolyte for medium and high pressures, 1.6-decanedicarboxylic acid (Japanese Patent Publication No. 13293/1983 ``Electrolyte for driving electrolytic capacitors'') is known.
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 in high-temperature load tests and high-temperature no-load tests, An extreme decrease in capacitance 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 solves the above-mentioned drawbacks by using 8,11-dimethyl-1,18-octadecanedicarboxylic acid as the main solute of the electrolytic solution and adding phosphoric acid or a salt thereof. The present invention provides an electrolytic capacitor with high performance and high reliability by reducing the specific resistance of the electrolytic solution and reducing the tangent of the loss angle and the equal series resistance.

Here, the structural formula of 8,11-dimethyl-1,18-octadecanedicarboxylic acid is as follows.

[Example] Next, an example of an electrolytic solution according to the present invention in which 8,11-dimethyl-1,18-octadecanedicarboxylic acid or a salt thereof is dissolved in ethylene glycol and phosphoric acid or a salt is added will be described. Examples are 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 (
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 6 values of the characteristics at the initial stage and after the test are the average values of 820 electrolytic capacitors.) In 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 8,11-dimethyl-1,18-octadecanedicarboxylic acid or its salt as a solute and adding phosphoric acid or a salt, the resistivity can be lowered and the tangent of the loss angle can be reduced. It 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] Among the components of the electrolytic solution according to the present invention, 8. The amount of solute of 11-dimethyl-1,18-octadecanedicarboxylic acid is preferably in the range of 8 to 30 wt%; when 8 wt% is ungrooved, the specific resistance increases, and on the other hand, when it exceeds 30 wt%, the spark voltage of the electrolyte increases. None of them can be put to practical use because of the low energy consumption.

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 effect of addition is small, and if it exceeds 3 wt %, the spark voltage of the electrolyte decreases, so that it cannot be put into practical use.

Claims (1)

[Claims] (1) An electrolytic solution for driving an electrolytic capacitor, characterized in that the main solute is 8,11-dimethyl-1,18-octadecanedicarboxylic acid or a salt thereof, and phosphoric acid or a salt thereof is added.