JPH03181114A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PURPOSE:To reduce the resistivity in the wide temperature range extending from low temperature to high temperature and besides to raise sparking voltage by using a solvent mainly composed of gamma-butyrolactone, and also adding boric acid dissolved in ethylene glycol. CONSTITUTION:First, tetramethyl ammonium salt of phthalic acid is dissolved as a solvent in the solvent mainly composed of gamma-butyrolactone, thus a low resistivity value is obtained though sparking voltage is low. Next, boric acid is added in such mixed liquid so as to elevate the sparking voltage without elevating the resistivity much. At this time the boric acid is hardly dissolved in the solvent mainly composed of gamma-butyrolactone, so boric acid is dissolved in a lactone solvent in such a means as to dissolve the boric acid once by the ester reaction with ethylglycol and add boric acid in the mixed liquid between gamma-butyrolactone and tetramethyl ammonium salt. As a result, sparking voltage rise can be made possible without elevating the resistivity value much.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electrolytic solution for driving an electrolytic capacitor.

[Prior Art] Conventionally, as an electrolytic solution for driving an electrolytic capacitor, an electrolytic solution in which an organic carboxylic acid such as adipic acid is dissolved in ethylene glycol has been used. However, ethylene glycol has drawbacks such as a significant increase in viscosity at low temperatures, and an increase in specific resistance or associated loss at high temperatures.

On the other hand, as an electrolytic wave that improves the characteristics at low temperatures, there is an electrolytic solution for driving an electrolytic capacitor that uses dimethylformamide or γ-butyrolactone as a main solvent and a salt of maleic acid or phthalic acid as a solute.

However, when these electrolytic capacitor driving electrolytes are used, although the specific resistance is sufficiently low, the spark voltage is low, and there is a drawback that they can only be used for low voltage capacitors of 50 V class or lower.

[Problem to be solved by the invention] As mentioned above, the conventional electrolytic wave for driving an electrolytic capacitor is
It has disadvantages such as an increase in viscosity in a low temperature range, an increase in specific resistance in a high temperature range, and an accompanying increase in loss. In addition, for improvement, electrolytes using dimethylformamide or γ-butyrolactone as the main solvent and maleic acid or phthalic acid salts as solutes do not have these drawbacks.
A new drawback was that the spark voltage was lower, making it compatible only with low-voltage capacitors.

The present invention was proposed to solve the problems of the prior art, and its purpose is to reduce the specific resistance in a wide temperature range from low to high temperatures, and to reduce the spark voltage. 1. By increasing the voltage by 100 V, it is possible to contribute to the realization of long-life and highly reliable electrolytic capacitors that have stable and high characteristics over a wide temperature range. Moreover, it can be used for higher voltage capacitors, specifically 100V class capacitors. An object of the present invention is to provide an excellent electrolytic solution for driving an electrolytic capacitor, which can be used in capacitors.

[Means for Solving the Problems] The electrolytic solution for driving an electrolytic capacitor according to the present invention is produced by dissolving teI-ramethylammonium salt of phthalic acid as a solute in a solvent mainly composed of γ-butyrolactone, and further dissolving teI-ramethylammonium salt of phthalic acid as a solute. It is characterized by adding and dissolving boric acid dissolved in , and P-nitrophenol or P-nitrobenzoic acid.

The amounts of each material added are as follows: ethylene glycol concentration is 15-20%, boric acid concentration is 0.5-1%, and P-nitrophenol or P-nitrobenzoic acid concentration is 0.5%.
It is desirable that it be ~1%. In this case, the reason why the concentration of ethylene glycol is 15 to 20% is because if it is less than 15%, dissolution of boric acid will not proceed smoothly, and if ethylene glycol is added in an amount exceeding 20%, This is because the specific resistance increases.

[Function] The action of the electrolytic solution for driving an electrolytic capacitor of the present invention having the configuration as shown below is as follows.

First, when a tetramethylammonium salt of phthalic acid is dissolved as a solute in a solvent mainly composed of γ-butyrolactone, a low specific resistance value can be obtained although the spark voltage is low.

By adding boric acid to such a mixed solution of γ-butyrolactone and tetramethylammonium salt, it is possible to increase the spark voltage by 1" without increasing the specific resistance value too much.

In this case, since boric acid is difficult to dissolve in a solvent mainly composed of γ-butyrolactone, in the present invention, boric acid is first dissolved by an esterification reaction with ethylene glycol, and in this state, γ-butyrolactone and tetra By the innovative means of adding boric acid to the mixture with methylammonium salt, it has become possible to dissolve boric acid in the γ-butyrolactone solvent, and as a result, as mentioned above, the specific resistance value has increased. This makes it possible to increase the spark voltage without increasing too much.

[Example] Examples of the electrolytic solution for driving an electrolytic capacitor according to the present invention will be described below.

First, three types of electrolyte solutions according to the prior art (Conventional Examples 1 to 3) and two types of electrolyte solutions according to the present invention (Examples 1 and 2) were prepared at the composition ratios shown in Table 1. When the spark voltage (V) and specific resistance at 25° C. of each electrolytic solution were investigated, the results shown in Table 2 were obtained.

In addition, a capacitor with the same rating of 63V-680μF was prototyped using five types of electrolytes according to the conventional technology and the present invention as described above, and a high-temperature load test was conducted at a constant temperature of 105°C with the application of the rated voltage. , the results shown in Tables 3 and 4 were obtained.

Tables 3 and 4 show the characteristics of capacitance (μF) and tangent of loss angle (tan δ), and Table 6 shows the initial characteristics, the characteristics after 1000 hours, and the characteristics after 2000 hours. Characteristics are shown comparatively. (The following is a blank space) As shown in Tables 3 and 4 above, Conventional Examples 2 and 3
In this case, the explosion-proof valve has already activated at the initial stage, and the 63V
It turns out that it is impossible to use it for personal purposes. In addition, although Conventional Example 1 has some characteristics at the initial stage, the characteristics deteriorate significantly after that, and 10
After 00 hours of high temperature 11 load test, the capacitance is 7.3
% decreased, and the tangent of the loss angle also increased to 0.082, and furthermore, the explosion-proof valve operated after 1500 hours.

In comparison with these conventional examples 1 to 3, Example 1 according to the present invention.
2, even after a 1000-hour high-temperature load test, the decrease in capacitance remained at about 2.0% to 2.1%, and only a slight increase was observed in the tangent of the loss angle. I can't do it. Furthermore, even after 2000 hours, the capacitance decreased by only 4.3% to 4.5% compared to the initial value, and the loss angle tangent also decreased by 0.042 to 0.045. The value has been kept to a sufficiently low level. from these things,
Electrolytic solution for driving an electrolytic capacitor according to the present invention (Example 1.
When using 2), it is possible to realize an electrolytic capacitor that has very little change over time at high temperatures, maintains stable and high characteristics, and has a long life, especially for high voltage capacitors exceeding 50V. It turns out that it can also be used. Furthermore, each of the above-mentioned electrolytes according to the present invention (implementation IJi
1, 2) has been confirmed to be able to withstand the use of capacitors up to 100V class.

[Effects of the Invention] As explained above, the electrolytic solution for driving an electrolytic capacitor of the present invention uses a solvent mainly composed of γ-butyrolactone and adds boric acid dissolved in ethylene glycol. Compared to the electrolytic solution shown in Figure 1, the specific resistance is reduced over a wide temperature range from low to high temperatures, and the spark voltage is increased.

Therefore, by using the electrolytic solution for driving electrolytic capacitors of the present invention, it is possible to contribute to the realization of long-life, highly reliable electrolytic capacitors that have stable and high characteristics over a wide temperature range compared to conventional capacitors. Moreover, it is possible to provide an excellent electrolytic solution for driving an electrolytic capacitor that can be used in a 100V class capacitor, and a great effect can be obtained in terms of industrial practicality.

Claims (2)

[Claims] (1) Dissolving tetramethylammonium salt of phthalic acid as a solute in a solvent mainly composed of γ-butyrolactone,
Furthermore, boric acid dissolved in ethylene glycol and P-
An electrolytic solution for driving an electrolytic capacitor, characterized in that nitrophenol or P-nitrobenzoic acid is added and dissolved therein. (2) The concentration of ethylene glycol is 15-20%, the concentration of boric acid is 0.5-1%, and the concentration of P-nitrophenol or P-nitrobenzoic acid is 0.5-1%. The electrolytic solution for driving an electrolytic capacitor according to claim 1.