JPH0449249B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field The present invention relates to an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as electrolytic solution). (b) Prior Art Recently, with the development of electronic technology, the operating temperature range of electronic components is expanding, and electrolytic capacitors are also required to have a wide temperature range. Conventionally, electrolytes for electrolytic capacitors have been known to contain ethylene glycol (hereinafter referred to as EG) as the main solvent and ammonium salts or amine salts of organic acids such as adipic acid, formic acid, and benzoic acid as solutes. ing. In electrolytic capacitors using the electrolytic solution described above, the viscosity of the electrolytic solution increases at low temperatures such as -55°C, resulting in deterioration of capacitor characteristics. In order to improve low-temperature properties, N-methylformamide is used as a solvent as disclosed in Japanese Patent Publication No. 55-39898, and N-methylformamide is used as a solvent.
As disclosed in Japanese Patent No. 57854, a method using methyl alcohol and dimethyl sulfoxide has been proposed. (c) Problems to be Solved by the Invention However, when a load test is performed on these electrolytes at a high temperature such as 105°C, the electrolyte passes through the sealing material and evaporates to the outside during the load. This resulted in deterioration of capacitor characteristics. Additionally, adding water to the electrolyte improves the properties at low temperatures, but at high temperatures such as 105°C, the sealing material swells, leading to destruction. An object of the present invention is to provide an electrolytic solution that can provide an electrolytic capacitor with stable characteristics from an ultra-low temperature of -55°C to a high temperature of 105°C. (d) Means for solving the problems The electrolytic solution of the present invention contains ethylene glycol 30 to 90%
It is characterized in that 5 to 15 g of ammonium formate and 1 to 10 g of adipic acid or its salt are dissolved in 100 ml of a mixed solvent consisting of 70 to 10% of N-ethylformamide (hereinafter referred to as NEF). (E) Effect The present invention uses a mixed solvent of EG and NEF as a solvent, and the mixing ratio is 30 to 90% EG and 70 to 70% NEF.
By setting it to 10%, the advantages of EG and NEF can be effectively utilized, and the temperature range from -55℃ to 105℃
Stable capacitor characteristics can be obtained up to high temperatures. The above mixing ratio is important because NEF is 10
If it is less than 70%, the viscosity will increase at low temperatures and the conductivity will decrease, and if it exceeds 70%, the electrolyte will permeate through the sealing material and dry up faster, and the solute in the electrolyte will This is because the solubility of the oxide is significantly reduced and sufficient electrical conductivity cannot be obtained. (F) Example The present invention uses a mixed solvent of EG and NEF, and the mixing ratio is EG:NEF=30-90 (%):70-10
(%). 100ml of this mixed solvent of EG and NEF
5 to 15 g of ammonium formate and 1 to 10 g of adipic acid or its salt are dissolved in the electrolyte. That is, by using ammonium formate and adipic acid or a salt thereof as a solute, an electrolytic solution with low resistivity can be realized. Moreover, when the amount of these solutes exceeds the upper limit, precipitation of the solute occurs, and when the amount falls below the lower limit, sufficient electrical conductivity cannot be obtained. Furthermore, preferably 1 to 2 g of mannitrate and 0.2 to 1 g of dinitrobenzene or nitrobenzoic acid are added. Hereinafter, the present invention will be explained in more detail with reference to specific examples. Table 1 shows two types of electrolytes A and D as typical examples of the present invention and electrolytes B, C, E, and F for comparison.

【table】

[Table] The above electrolytes A to F are rated at 25V and 1000μF, respectively.
An aluminum electrolytic capacitor was fabricated by impregnating the element. Table 2 shows the results of measuring the low temperature characteristics, and Table 3 shows the results of a high temperature load test by applying the rated voltage in a high temperature atmosphere of 105°C. The structure of the sample capacitor mentioned above is a well-known structure, in which a capacitor element consisting of a chemically etched aluminum box and a cathode foil wrapped between separator paper is impregnated with electrolyte, and this element is placed in an aluminum case. It was stored and sealed using rubber packing.

【table】

[Table] Here, C is capacitance, Z is impedance, Z/
Z (20°C) is the impedance ratio.

[Table] Here, LC is the leakage current after 15 seconds, and ΔC/C is the capacitance change rate. From Table 2, it can be seen that in electrolytic solution C in which 95 ml or more of EG was mixed with 100 ml of solvent, and in electrolytic solution B in which EG was used as a solvent, the capacitor characteristics at a low temperature of -55°C deteriorated. Also, from Table 3, NEF is 80% for 100ml of solvent.
Electrolyte F mixed with more than ml and NEF as solvent
It can be seen that the capacitor characteristics deteriorated in electrolyte E using electrolyte E in a high temperature load test at 105℃ for 2000 hours. On the other hand, in the electrolytes A and D of this example, the characteristics did not deteriorate at a low temperature of -55℃, and the
Even after a high-temperature load test at ℃, the capacitor characteristics do not deteriorate, and stable capacitor characteristics are obtained from low to high temperatures. In addition, 1 to 2 g of mannitrate per 100 ml of solvent.
By adding 0.2 to 1 g of dintrobenzene or nitrobenzoic acid to 100 ml of solvent, there is an effect of absorbing hydrogen, and the life can be extended. (g) Effects of the Invention As explained above, the electrolyte according to the present invention eliminates deterioration of capacitor characteristics even under high-temperature loads such as 105°C without impairing life characteristics, and improves capacitor characteristics at low temperatures. It has great industrial effects, such as being able to effectively prevent deterioration.

Claims (1)

[Claims] 1. 5 to 15 g of ammonium formate and 1 to 10 g of adipic acid or its salt are dissolved in 100 ml of a mixed solvent consisting of 30 to 90% ethylene glycol and 70 to 10% N-ethylformamide. An electrolytic solution for driving electrolytic capacitors characterized by: 2 Mannitol 1 for 100 ml of the above mixed solvent
2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, characterized in that up to 2 g of the electrolytic solution is dissolved therein. 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein 0.2 to 1 g of dinitrobenzene or nitrobenzoic acid is dissolved in 100 ml of the mixed solvent.