JPS6265406A - Electrolyte for driving aluminum electrolytic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrolytic solution for driving an aluminum electrolytic capacitor (
(hereinafter referred to as electrolyte).

Conventional technology A capacitor element made by winding chemically etched aluminum foil and cathode foil with separator paper in between is impregnated with electrolyte.
The driving electrolyte for an aluminum electrolytic capacitor, which has a structure in which this element is housed in an aluminum case with a rubber backing, is conventionally known to be a mixed solvent of ethylene glycol and water with an ammonium salt of carboxylic acid as a solute. It is being

Problems to be Solved by the Invention An electrolytic solution containing an ammonium salt of a carboxylic acid as a solute in a mixed solvent of ethylene glycol and water has an increased viscosity at low temperatures, which deteriorates the low-temperature characteristics of the capacitor. Furthermore, during a load test in a high-temperature atmosphere, the anodic oxide film and cathode foil of the capacitor reacted with water to generate hydrogen gas, which increased the pressure inside the capacitor and led to its destruction.

Means for Solving the Problems The present invention solves the above-mentioned problems by combining 50-97 wt% of T-butyrolactone and 50-wt% of ethylene glycol.
% to a mixed solvent consisting of 5 to 20 wt % of maleic acid, and the pH was adjusted to 3 to 7. % with triethylamine.
This is an electrolytic solution for driving an aluminum electrolytic capacitor, which is characterized by being adjusted within the range of 5.

As a driving electrolyte for aluminum electrolytic capacitors, T
- By adding maleic acid as a solute to a mixed solvent consisting of butyrolactone and ethylene glycol and adjusting the pH to 3 to 7.5 with triethylamine, deterioration of capacitor characteristics due to increase in resistivity can be suppressed even at low temperatures, and electrolytic It shows stable characteristics even in high-temperature reliability tests of capacitors.

Example Hereinafter, specific examples of the present invention will be described.

Table 1 shows examples of electrolytes of the present invention (sample symbols A, B
The composition ratio of the electrolytic solution, the specific resistance of the same electrolytic solution at 30°C, and the specific resistance of the same electrolytic solution at -55°C are shown for SC) and a conventional electrolytic solution (sample symbol D) for comparison.

Table 2 shows the low-temperature characteristics results of aluminum electrolytic capacitors using each of the above electrolytes (sample symbols A, BSC, and D). All capacitor samples are aluminum electrolytic capacitors with a rating of 35 V and 220 μF.

Tables 2 and 3 show the high temperature load conditions and experimental results of capacitors using the above electrolytes (sample symbols A, B, C, and D) in an atmosphere of 105°C.

Table 3 As is clear from the above examples, maleic acid was added as a solute to the mixed solvent of the present invention consisting of T-butyrolactone and ethylene glycol, and triethylamine was used to purify the mixture.
Electrolyte solution with H adjusted to 3 to 7.5 (sample symbols A, B, C
) using an aluminum electrolytic capacitor (sample group number 1
．． 2.3 and 5.6.7), it was demonstrated that the low-temperature properties as well as the high-temperature load test properties were significantly improved.

The results of various experiments show that if the amount of ethylene glycol in the solvent of the electrolytic solution of the present invention exceeds 50 wt%, the low-temperature characteristics will deteriorate, and if it is less than 3 wt%, the capacity change rate in the high-temperature load test will increase.

Furthermore, if the amount of maleic acid is less than 5 wt % with respect to the mixed solvent, the resistivity will be high and the tangent of the loss angle will increase, and if the amount exceeds 20 wt %, the spark generation voltage will decrease.

Further, if the pH of the electrolytic solution of the present invention is less than 3 or more than 7.5, leakage current increases, resulting in a decrease in high temperature load life characteristics.

In addition to the above-mentioned examples, similar results were obtained by repeated experiments with varying mixing ratios of T-butyrolactone, ethylene glycol, maleic acid, and triethylamine within a limited range.

Effects of the invention As described above, the aluminum electrolytic capacitor F according to the present invention
Compared to conventional electrolytes, the dynamic electrolyte maintains extremely stable characteristics from low to high temperatures, making it possible to provide highly reliable electrolytic capacitors, which have great industrial and practical value. It is something.

Claims (1)

[Claims] To a mixed solvent consisting of 50 to 97 wt% of γ-butyrolactone and 50 to 3 wt% of ethylene glycol, 5 to 20 wt% of maleic acid is added to the mixed solvent as a solute, and the pH is adjusted to a range of 3 to 7.5 with triethylamine. Electrolyte for driving aluminum electrolytic capacitors.