JPH0451509A - Electrolyte for driving electrolytic capacitor - Google Patents

Abstract

PURPOSE:To get electrolyte for driving an electrolytic capacitor, wherein spark generation voltage is increased and reliability at high temperature is improved, by adding polyglyceline to the electrolyte consisting of an organic solvent and a solute. CONSTITUTION:Polyglyceline is added to the electrolyte consisting of an organic solvent and a solute. The quantity of added polyglyceline is 0.5-30wt.%. Moreover, the organic solvent shall be composed mainly of ethylene glycol or gamma- butyrolactone.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to electrolytic capacitors, and particularly to an electrolytic solution for driving an electrolytic capacitor with a high spark voltage.

(Prior art) Conventionally, an electrolytic solution (hereinafter referred to as electrolytic solution) for driving medium-high voltage electrolytic capacitors has been prepared by dissolving boric acid and aqueous ammonia or an ammonia salt of boric acid in a solvent mainly composed of ethylene glycol. However, recently, salts such as butyloctanic acid, azelaic acid, and adipic acid have also been used.

Furthermore, electrolytes for low-pressure, high-conversion properties have been developed in which carboxylic acids such as maleic acid and phthalic acid, or their amine salts and quaternary ammonium salts are dissolved in a solvent mainly composed of γ-butyrolactone. .

(Problem to be solved by the invention) Although it is possible to increase the spark generation voltage with the boric acid electrolyte that has been conventionally used for medium and high voltage applications, it has the drawback of increasing viscosity and specific resistance. be. Also, 1
When used at a high temperature of 0.5°C, esterification occurs and a large amount of water is formed, which reacts with the electrode foil and causes problems such as valve operation, making it difficult to use at high temperatures.

On the other hand, although it is possible to lower the viscosity and specific resistance of organic acid electrolytes, it has been difficult to use them at high pressures of 450 WV or higher due to restrictions on spark generation voltage and corrosion resistance.

In addition, it is difficult to increase the spark generation voltage with a low-pressure γ-butyrolactone electrolyte, and it has not been possible to use it above 100 WV.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an electrolytic solution for driving an electrolytic capacitor that increases spark generation voltage and improves reliability at high temperatures.

(Means for Solving the Problems) The present invention according to the above object is characterized in that polyglycerin is added to an electrolytic solution consisting of an organic solvent and a solute. The amount of polyglycerin added is preferably 0.5 to 3 Qwt%.

Said I! As the solvent, one mainly composed of ethylene glycol or one mainly composed of T-butyrolactone is suitable.

Here, polyglycerin is a mixture of polymers with a degree of polymerization of 2 to 15 obtained by condensation polymerization of glycerin, and the degree of polymerization can be changed as necessary, or low fractions can be removed by an appropriate separation operation (thin film vacuum distillation, etc.). It can be obtained by known techniques such as those obtained by Also, add 1 liter of water to adjust the viscosity.
It may be included at around 0%, or the purpose of the present invention can of course be achieved even if it is anhydrous.

(Function) Since polyglycerin has a larger molecular weight than glycerin, it is thought that by adhering to the oxide film surface of the electrode foil, the spark generation voltage increases to suppress dielectric breakdown.

(Example) Hereinafter, the present invention will be described in detail based on Examples.

Table 1 shows the characteristics of the electrolyte solutions of the conventional example and the example according to the present invention. Conventional Example 1 uses a boric acid electrolyte, and although the spark generation voltage is high, the specific resistance is also high. Conventional Examples 2 and 3 are organic acid-based electrolytes, and although the specific resistance can be lowered, the spark generation voltage is lowered. Moreover, the amount of solute could not be increased.

Conventional Example 4 is an example in which glycerin is used as a subsolvent to increase the spark generation voltage. On the other hand, Examples 1 and 2 are cases in which polyglycerin is added to Conventional Examples 2 and 3, respectively, and the spark generation voltage can be increased by about 30 to 45V. In contrast to Conventional Example 4, Example 3 is an example in which the specific resistance and the spark generation voltage are adjusted to be the same using an organic acid based polyglycerin.

Tables 1 and 2 show a comparison between conventional examples and examples of T-butyrolactone. The spark generation voltage can also be increased by adding polyglycerin.

Table 2 Next, using the electrolytes of Conventional Example 4 and Example 3,
Fabricate a 0V 100μF electrolytic capacitor and heat it to 105°C.
Table 3 shows the results of a 2000 hour load test. Example 3 had good results. Further, in Example 3, since the amount of solute was increased, no corrosion occurred.

The polyglycerin used in this example had an average degree of polymerization of 6, and had a viscosity of 175,000 Cp in anhydrous form, but was made to have a viscosity of 4,500 Cp by adding 10% water.

The amount of polyglycerin added is Q. If it is less than 5 wt%, it will have no effect on the spark generation voltage, and if it exceeds 30 wt%, the specific resistance will increase, so it should be 0.5 to 3.
0 wt% is preferred.

(Effects of the Invention) As described above, according to the present invention, it is possible to increase the spark generation voltage, and it is possible to provide an electrolytic solution that is stable even at high temperatures.

Claims (4)

[Claims] 1. An electrolytic solution for driving an electrolytic capacitor characterized by adding polyglycerin to an electrolytic solution consisting of an organic solvent and a solute. 2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the amount of polyglycerin added is 0.5 to 30 wt%. 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1 or 2, wherein the organic solvent is mainly composed of ethylene glycol. 4. The electrolytic solution for driving an electrolytic capacitor according to claim 1 or 2, wherein the organic solvent is mainly composed of γ-butyrolactone.