JPS6013293B2 - Electrolyte for electrolytic capacitors - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electrolytic solution for electrolytic capacitors.

Various characteristics of the electrolytic solution used in electrolytic capacitors, such as specific resistance and spark voltage, generally have a large influence on the characteristics of electrolytic capacitors. For example, electrolytic capacitors for medium and high voltages are required to have excellent withstand voltage characteristics and be stable against deterioration due to storage, so shelf acids or salts thereof are added to solvents such as ethylene glycol. An electrolytic solution containing . However, since such an electrolytic solution has a high specific resistance, it has the drawback of increasing capacitor loss, causing heat generation, and promoting thermal deterioration. In order to improve these drawbacks, electrolytes containing organic dicarboxylic acids such as azelaic acid and sebacic acid or their salts as solutes are sometimes used; however, due to the low solubility of organic dicarposo acids, crystallization occurs at low temperatures. However, it cannot escape the disadvantage that it tends to precipitate and deteriorate the low-temperature characteristics of the capacitor. In view of the above points, it is an object of the present invention to provide an electrolytic solution for electrolytic capacitors that has low specific resistance, high solubility, and high spark generation voltage.

In order to achieve the above object, the present invention provides an electrolytic solution for an electrolytic capacitor, which is characterized in that it contains butyloctanedioic acid or a salt thereof as a solute.

That is, as shown in the example, an electrolytic solution is formed by mixing only ethylene glycol as a solvent and butyl octane diammonium as a solute in arbitrary proportions, and in particular, the former is 92% by weight and the latter is 8% by weight. In the event that
Conventional electrolyte (ethylene glycol 92% by weight, melting cost 8
%), specific resistance, solubility, and spark generation voltage, as shown in the table below.

As can be seen from the table, the electrolyte according to the present invention has a resistivity that is about 1' lower than that of ammonium sulfate, and is also smaller or the same as that of ammonium dicarboxylate, reducing the loss of the capacitor. can.

The solubility also shows the same value as that of ammonium sulfate, but it is 2 to 3 times higher than that of organic dicarboxylic acid ammonium, and a capacitor with improved low temperature characteristics can be obtained. Further, the spark generation voltage according to the present invention is higher than that of the conventional ammonium chlorate or organic ammonium dicarboxylate electrolyte, and generally the withstand voltage of the capacitor can be higher than that of the conventional electrolyte. Actually, 330V2
For a 001F aluminum electrolytic capacitor, a secondary solution was prepared in which 40% by weight of ammonium chloride was added to 6% by weight of ethylene glycol so that the losses at 25'0 were almost equal, that is, the resistivities were almost the same. Electrolyte (3
The loss of the electrolyte solution of the present invention (specific resistance of 4,050 stations at 30q0), which is obtained by adding 8% by weight of butyl octaso di-ammonium to 92% by weight of ethylene glycol. When the temperature characteristics were measured, the results shown in FIG. 1 were obtained.

In other words, in conventional product A, ammonium sulfate was added to ethylene glycol close to the solubility limit in an attempt to match the specific resistance, resulting in some crystal precipitation at low temperatures and a sharp increase in loss. The loss of the invention B at -2030 is approximately 1/1 of that of the conventional one A.
2. In addition, Fig. 2 shows the temperature characteristics of the rate of change in solubility, and at }loo○ and -2030, the invention B is 1/2 that of the conventional A, indicating that the low-temperature characteristics are improved. .Capacitors (330V, 200μF) according to the embodiments and subsidiary examples of the present invention were manufactured and tested.

Table 1 shows the data after 85q0 high temperature load test 100 hours - Table 2 shows the data after 500 hours 85°C high temperature no load test. Table 1 Table 2 As can be seen from the above table, the secondary product (boric acid electrolyte) contains a large amount of water due to esterification, so gas generation was observed in the high-temperature load test and high-temperature no-load test. However, with the product of the present invention, no abnormalities were observed in the characteristics or in the external appearance inspection of the capacitor in all tests, and good results were obtained.

Note that only butyl octanedioic acid or its salts may be used as the solvent.

As described above, according to the present invention, it is possible to obtain an electrolytic solution for electrolytic capacitors that has low resistivity, high solubility, and high spark voltage, and therefore reduces loss and improves low-temperature characteristics, especially in medium-high voltage electrolytic capacitors. can.

[Brief explanation of the drawing]

Figures 1 and 2 show the temperature characteristics of loss and capacitance change rate of an aluminum electrolytic capacitor impregnated with a conventional electrolyte containing ammonium chlorate as a solute and an aluminum electrolytic capacitor impregnated with an embodiment of the present invention, respectively. This is a graph showing. A: Conventional example, B: Present invention. Figure 7 Departure Figure 2

Claims (1)

[Claims] 1. An electrolytic solution for an electrolytic capacitor, which contains butyl octanedioic acid or a salt thereof as a solute.