JPH0262026A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain an electrolyte whose specific conductivity and discharge voltage are high and whose corrosion resistance is strong by a method wherein 3-methyladipic acid or its salt and benzoic acid or its salt are dissolved in ethylene glycol or gamma-butyrolactone. CONSTITUTION:3-methyladiplc acid or its salt and benzoic or its salt are dissolved in ethylene glycol or gamma-butyrolactone. An ammonium salt, a secondary amine salt, a tertiary amine salt or a quaternary ammonium salt is preferable as the salt of methyladipic acid or benzoic acid. By using 3-methyladipic acid or its salt as a dicarboxylic acid in a side chain, it is possible to have an excellent chemical formation property and solubility and to obtain a high discharge voltage and high conductivity as compared with those of a dicarboxylic acid in a normal chain. Thereby, it is possible to obtain an electrolyte whose corrosion resistance is strong.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an electrolytic capacitor.

Specifically, it relates to an electrolytic solution for driving an aluminum electrolytic capacitor.

Conventional technology Traditionally, it has been used as an electrolyte for driving electrolytic capacitors.

Ammonium borate dissolved in ethylene glycol is used as an electrolyte. This type of electrolytic solution has a high discharge voltage, but has a drawback of low specific conductivity, which increases the loss of the electrolytic capacitor.

However, it is still not stable enough to degrade at high temperatures.

In order to improve the above-mentioned shortcomings, the special public
As seen in Japanese Patent No. 899, there is an example in which 3-methyladipic acid or a salt thereof is used in ethylene glycol to achieve high conductivity while maintaining a high discharge voltage.

Problems to be Solved by the Invention However, as a conventional problem, in recent years, attention has been paid to the corrosivity of capacitors when cleaning printed circuit boards with chlorinated solvents. When using this material, the characteristics of high discharge voltage and high specific conductivity can be obtained, but the drawback is that the corrosion resistance is insufficient and the deterioration is large at high temperatures.

The present invention solves these conventional drawbacks by providing an electrolytic solution that has both high discharge voltage and high conductivity, and also has excellent corrosion resistance, and improves the loss characteristics of electrolytic capacitors and The purpose is to extend the life of the inside and improve corrosion resistance.

Means for Solving the Problems In order to solve the above problems, the present invention provides ethylene glycol or r-butyrolavone or a mixed solvent thereof.
This is an electrolytic solution for driving an electrolytic capacitor that dissolves 3-methyladipic acid or its salt and benzoic acid or its salt.

As the salts of 3-methyladipic acid and benzoic acid, ammonium salts, secondary amine salts, tertiary amine salts, and quaternary ammonium salts are preferable. Among the secondary amine salts, dimethylamine, diethylamine, and tertiary amine salts are preferable. Among them, trimethylamine, triethylamine, dimethylethylamine, diethylmethylamine, and quaternary ammonium salts, tetramethylammonium and tetraethylammonium are particularly preferred.

The amount of 3-methyladipic acid or its salt added is preferably 1 to 30 times the amount of electrolyte. This is because if it exceeds 1% by weight, the specific conductivity is low, and if it exceeds 30% by weight, it will not dissolve.

The amount of fragrant acid or its salt added is 0.0% relative to the amount of electrolyte.
It is preferably 1 to 10% by weight. If it is less than 0.1% by weight, it has no effect on high-temperature deterioration and corrosion resistance;
This is because if the amount is more than % by weight, the discharge voltage will not decrease.

Function: The electrolytic solution of the present invention uses 3-methyladipine or a salt thereof and benzoic acid or a salt thereof.
3-methyladipic acid or its salt, which is a dicarboxylic acid in the side chain, has superior chemical formation properties and solubility, and can provide high discharge voltage and high conductivity compared to dicarboxylic acids. By further adding benzoin or its salt,
It is thought that the resilience of the oxide film improves and it becomes resistant to chlorine ions.

Example An embodiment according to the present invention will be described below.

Table 1 shows examples of the present invention and conventional electrolyte compositions, as well as conductivity and discharge voltage at room temperature.

(Hereinafter, blank) Table 2 shows the results of a voltage application test at 105° C. for aluminum electrolytic capacitors using the electrolytes of the conventional example and the example shown in Table 1.

The sample capacitor has a well-known structure, a chemically formed niche door! This is an aluminum electrolytic capacitor with a rating of 200 V and 68 μF, which is made by impregnating an electrolytic solution into a capacitor element made by winding reminium foil and cathode foil between separator paper, and then storing this element in an aluminum case and sealing it. Tests were also performed with 1 μl of 1,1.1-)lichloroethane injected into the internal elements of the capacitor to accelerate corrosion.

From Table 1, the electrolytic solution according to the present invention is as follows: Example 1゜2.3
As is clear from the above, excellent characteristics such as a small drop in discharge voltage and a high specific conductivity can be obtained. Also.

As is clear from Table 2, in the capacitor using the electrolyte according to the present invention, no corrosion is observed and the corrosion resistance is improved compared to the conventional electrolyte.

Next, in Table 1, the test results of aluminum electrolytic capacitors using the conventional example and the electrolytes of Examples 1 and 4.5 at 106°C without voltage application are shown in Figure 1.b , shown in c.

The test capacitors used were the same as those used in the tests shown in Table 2, and the tests were conducted with n=20 capacitors.

Here, Fig. 1a shows the capacitance change, Fig. 1 shows the loss angle tangent change, and Fig. 1C shows the leakage current change, all of which were tested at 106°C without voltage application. I did it.

Especially when comparing the conventional example shown in FIG. 1 and the fourth embodiment.

Due to changes in leakage current, the conventional example decreased to 9o after 2000 hours.
While it is high in μm, it is as low as 30 μm in the example. In addition, in the conventional example and Example 5, the tangent change in the loss angle is significantly lower than that in the conventional example at the initial stage and after 200 hours. It can be seen that in Example 1 as well, the change in capacitor characteristics is small and improved compared to the conventional example.

Effects of the Invention As described above, according to the present invention, it is possible to provide an electrolytic solution that has higher specific conductivity and discharge voltage than conventional electrolytic solutions and has strong corrosion resistance. Therefore, it is possible to provide a highly reliable capacitor at high temperatures, which is of great industrial value.

[Brief explanation of the drawing]

Figure 1 shows the rating 2 using the conventional electrolyte and the electrolyte of the present invention.
Figure 1A shows the change in capacitance, Figure 1 shows the tangent change in loss angle, and Figure 1C shows the change in characteristics of a 00V68μF aluminum electrolytic capacitor at 105°C with no rated voltage applied. is a characteristic diagram showing changes in leakage current.

Claims (10)

[Claims] (1) An electrolytic solution for driving an electrolytic capacitor, characterized in that 3-methyladipic acid or a salt thereof and benzoic acid or a salt thereof are dissolved in ethylene glycol, γ-butyrolactone, or a mixed solvent thereof. (2) The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the salts of 3-methyladipic acid and benzoic acid are ammonium salts. (3) The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the salts of 3-methyladipic acid and benzoic acid are secondary amine salts. (4) The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the salts of 3-methyladipic acid and benzoic acid are tertiary amine salts. (5) The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the salts of 3-methyladipic acid and benzoic acid are quaternary ammonium salts. (6) The electrolytic solution for driving an electrolytic capacitor according to claim 3, wherein the secondary amine is dimethylamine or diethylamine. (7) The electrolytic solution for driving an electrolytic capacitor according to claim 4, wherein the tertiary amine is trimethylamine, triethylamine, dimethylethylamine, or diethylmethylamine. (8) The electrolytic solution for driving an electrolytic capacitor according to claim 5, wherein the quaternary ammonium is tetramethylammonium or tetraethylammonium. (9) The amount of dissolved 3-methyladipic acid or its salt is 1
The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the electrolytic solution is 30% by weight. (10) Dissolution amount of benzoic acid or its salt is 0.1 to 10
The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the electrolytic solution is % by weight.