JPS6013294B2 - Electrolyte for electrolytic capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrolytic solution for stabilizing the high-temperature life characteristics of electrolytic capacitors.

Conventional electrolytic solutions for electrolytic capacitors have had problems such as the need to add gas absorbents to improve high-temperature life characteristics.

The present invention is an electrolytic solution that utilizes an acid ester having an esterification rate of 5 to 90% obtained by reacting an alcohol with an organic acid salt, and is intended to solve the above-mentioned problems.

This will be explained below using examples.

Example 1 The composition ratio of the solvent ethylene glycol (hereinafter referred to as EG) or diethylene glycol (hereinafter referred to as DEG) as an alcohol and the solute ammonium sebacate (hereinafter referred to as AS) as an organic acid salt is shown in Table 1. FIG. 1 shows the relationship between the ester conversion rate of the acid obtained by reacting the EG and DEC with AS and the specific resistance of the electrolyte.

Note that the numbers attached to the curves are those listed in Table 1. Table 1 and FIG. 2 show the relationship between the acid esterification rate and the spark voltage using an electrolytic solution having the same composition as shown in Table 1 above.

Note that the numbers are the same as in FIG. 1, but Reference Examples 1 and 2 are not shown in FIG. 2 because their specific resistances are large. Generally, esters are obtained by reacting alcohol and acid, but water is produced during esterification.

Water is also generated when an electrolytic solution having the composition shown in Table 1 is esterified, but in the case of electrolytic capacitors using an electrolytic solution containing water, the aluminum oxide film corrodes, and the high-temperature life characteristics are particularly poor. If the product is left at a high temperature such as during a test, the generation of gas will be noticeable, which will significantly shorten the product life and pose a risk of explosion, so the inventor removed the water using the following method. In other words, EG and/or DEC to be esterified and AS are mixed at a high temperature above the boiling point of water. For example, when the mixing temperature is 110°C, the mixing time, esterification rate, mixing time, and electrolyte are as follows. The relationship between the amount of water contained therein is shown in Figure 9. The solid line indicates the esterification rate, and the numbers are B, D, F, and B shown in Table 1.
Day and b (AS2 Wt% + EG4 egg t% + DEG4 egg t%), d (AS desk% + EG4 enemy % + DEG4 skin t
%) and the moisture content is indicated by a dotted line.

As is clear from FIG. 9, the esterification rate is determined by the composition of the electrolytic solution in relation to the preparation time. In addition to evaporating and removing
The esterification rate, which is a chemical reaction, was controlled by the preparation time, and as a result, a non-aqueous electrolyte (in Figure 9, it contains 0.01 wt% water, but it is a collection amount and has no effect on the electrolyte). Obtainable. Next, Table 2 shows a comparison of the specific resistance and spark voltage of the electrolytes of the conventional example and the present invention.

Note that the numbers of the present invention are assigned in relation to Table 1. Table 2 Although the above-mentioned Examples 1 are all about the properties as an electrolytic solution, in FIG. 1, both Reference Examples 1 and 2 have a high specific resistance and cannot be used.

Moreover, in the case of the present inventions 1 to 6, FIG. 2 shows that the spark voltage increases until the acid esterification rate reaches 80%, and thus the chemical formation ability also increases, but when it exceeds 80%, the spark voltage decreases rapidly, but 90% It is clear that up to 5% can be used and shows a value almost equivalent to 5%. Furthermore, the solubility of AS, which is a solute, in a solvent (EG, DEG, or a mixed solvent of EG and DEG) is limited to 2 t% according to the inventor's experiments, and if it exceeds this, it will not dissolve. confirmed. Further, in an experiment using a mixed solvent of EG and DEG as a solvent, almost the same results as in the case of using EG or DEO as a single solvent were obtained. Example 2 A capacitor element with a rating of 315 V-220 μF was prepared by winding an electrode foil made of aluminum and capacitor paper, and the present invention 2-1 shown in Table 2 was applied to the capacitor element.
(EG9 skin t%, ASI skin t%, acid esterification rate 5%
) The relationship between the elapsed time and the rate of change in capacitance when an electrolytic capacitor impregnated with the electrolytic solution shown in (2), stored in a box by normal means, and sealed is exposed to a rated voltage at 125°C is shown in Table 3. Similarly, leakage current is shown in FIG. 4, and tan6 is shown in FIG. 5 as a curve J.

Curve K shows the characteristics of a conventional electrolytic capacitor of the same rating impregnated with an electrolytic solution (Conventional Example 2 in Table 2) consisting of EG9, t%, ASI, t%. As a result, the conventional example showed a slight difference in characteristics after 500 hours, except for leakage current, and the present invention showed almost unchanged characteristic values at 1000 hours, whereas the conventional example showed a large deterioration and a clear difference was observed. The effect is remarkable.

Example 3 A capacitor element with a rating of 500V-220〆F was prepared in the same manner as in Example 2, and this was used as the present invention 2-2 (EG
9 skin t%, ASI enemy %, acid esterification rate 80%.
Curve number L) Invention 5 (DEC9 skin%, ASI BiW
t%, acid esterification rate 80%, curve number M) The electrolyte shown in Invention 6 (DEG8%, AS2 skin t%, acid esterification rate 80%, curve number N) The relationship between the elapsed time and the capacitance change rate when the rated voltage was applied to the electrolytic capacitor soaked in the cellar at 125:00 and left was shown in the 6th section.
Similarly, the leakage current is shown in FIG. 7, and the leakage current is shown in FIG. 8.

Note that the numbers L, M, and N in the figure indicate the type of electrolyte as shown above as curve numbers. t%
) The characteristics of electrolytic capacitors of the same rating impregnated with an electrolyte consisting of

As a result, the present invention shows stable characteristic values in all cases, but in the conventional example, the deterioration was noticeable at 25 places and 3 at 50 places.
The value became unusable for both characteristics.

As described above in Examples 1 to 3, the present invention involves reacting 80 to 9 t% of EG or DEG or a mixed solvent thereof with 2 to 2 t% of ammonium sebacate to achieve an acid esterification rate of 5. By impregnating a capacitor element with this electrolytic solution, it is possible to provide an electrolytic capacitor that can be used at high voltage and has excellent high-temperature life characteristics.

[Brief explanation of drawings]

FIG. 1 is a curve diagram showing the relationship between the acid esterification rate and specific resistance of the electrolytic solution according to the present invention, and FIG. 2 is a curve diagram showing the relationship between the acid esterification rate and the spark voltage of the electrolytic solution according to the present invention. A curve diagram showing,
Figure 3 is a curve diagram showing the relationship between capacitance change rate and elapsed time at high temperatures for capacitors using the electrolyte according to the present invention, and Figure 4 is a curve diagram showing the relationship between leakage current and elapsed time. FIG. 5 is a curve diagram showing the relationship between tan6 and elapsed time. FIG. 6 is a curve diagram showing the relationship between tan6 and elapsed time. FIG. FIG. 7 is a curve diagram showing the relationship between the rate of change and elapsed time. FIG. 8 is a curve diagram showing the relationship between n6 and elapsed time. FIG. 9 is a curve diagram showing the relationship between blending time, esterification rate, and water content. Shigeru 2 Iso Kama 3 Kama 4 Tsuyoshi S Miso Shigeru Se Figure 7 Figure 8 *? Illustration of a heron

Claims (1)

[Claims] 1 Using 80 to 98 wt% of ethylene glycol, diethylene glycol, or a mixture thereof as a solvent, and using 2 to 20 wt% of ammonium sebacate as a solute, the solvent and solute are reacted to increase the esterification rate of the acid to 5 to 90 wt%.
% and water produced by the esterification is removed from the electrolytic solution for electrolytic capacitors.