JPH03225908A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain electrolytic capacitor electrolyte which can improve its capacitance characteristics, tandelta characteristics and leakage current characteristics when it is impregnated in the electrolytic capacitor by adding guanidine phosphate or guanylurea phosphate. CONSTITUTION:Polyhydric alcohol such as ethylene glycol or diethylene glycol is used as a solvent. 1.6-decandicarbonic acid or 1.6-decandicarbonic acid ammonium is used as solute. Guanidine phosphate or guanylurea phosphate is especially used as additive wherein the amount to be added is 0.01 to 5wt.%. Guanidine phosphate or guanylurea phosphate can prevent formation of complexes since 1.6-decandicarbonic acid reacts with an aluminum foil. Thus reduction in an initial capacitance value of a capacitor due to the complex, a deterioration at a high temperature region, etc., can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Prior Art) The present invention relates to an electrolytic solution for electrolytic capacitors that can be used at high temperatures.

(Prior Art) An electrolytic solution for an electrolytic capacitor uses, for example, an organic acid with a relatively large molecular weight or a salt thereof as a solute so that it can be used even in a high temperature range. As an organic acid solute, 1,6-decanedicarboxylic acid is known as disclosed in Japanese Patent Publication No. 13293/1983 (1).

(Problem to be solved by the invention) However, in an electrolytic solution containing 1,6-decanedicarboxylic acid as a solute, 1,6-decanedicarboxylic acid reacts with the aluminum foil forming the capacitor element to form a complex. Another drawback is that the initial capacitance value of the capacitor is low, and the capacitance decreases dramatically during high-temperature load tests and high-temperature no-load tests, and leakage current increases.

In order to improve these drawbacks, 1,6-decanedicarboxylic acid, for example, phosphoric acid or sulfuric acid (Japanese Patent Application Laid-Open No. 58-9220
6), maleic acid (Japanese Unexamined Patent Publication No. 5892208), citric acid (Japanese Unexamined Patent Publication No. 59-219920), etc.

However, these additives have low thermal stability and are less effective in improving properties in high temperature regions.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrolytic solution for electrolytic capacitors that improves the above-mentioned drawbacks, is stable in high-temperature ranges, and can improve the characteristics of electrolytic capacitors.

(2) (Means for Solving the Problem) In order to achieve the above object, the present invention provides a solution in which 1,6-decanedicarboxylic acid or a salt thereof is dissolved in a solvent containing polyhydric alcohol as a main component. The present invention provides an electrolytic solution for electrolytic capacitors in which at least one of guanidine phosphate and guanylurea phosphate is dissolved.

(Function) Guanidine phosphate and guanylurea phosphate can prevent 1°6-decanedicarboxylic acid and aluminum foil from reacting to form a complex. Therefore, the initial capacitance value of the capacitor becomes low due to the complex, and deterioration in a high temperature region can be suppressed.

(Example) Hereinafter, the present invention will be explained based on examples.

As a solvent, use polyhydric alcohol such as ethylene glycol or diethylene glycol.

Solutes include 1,6-decanedicarboxylic acid and 1°(3) Ammonium 6-decanedicarboxylate is used.

In particular, guanidine phosphate and guanylurea phosphate are used as additives, and are added in an amount of 0.01 to 5 wt%.

In addition, aqueous ammonia is added as a pH adjuster, and boric acid and the like are added to improve chemical conversion properties.

Next, when the specific resistance and spark voltage were measured for the electrolytic solution of the example of the present invention and the conventional electrolyte, the results shown in Table 1 were obtained. The temperature of the electrolytic solution during measurement is 30°C for specific resistance and 85°C for spark voltage.

Margin below.

(4) Table 1 (5) (6) (7) (8) (9) As is clear from Table 1, according to Examples 1 to 10, the specific resistance is 460 to 510Ω・cJ11 spark voltage is 42
5 to 445 ■. Conventional examples 1 to 5 have a specific resistance of 570 to 600Ω・C11rN spark voltage of 41
It becomes 0-430V. Comparing the two, Examples 1 to 10 have lower specific resistances than Conventional Examples 1 to 5, about 77% to 8(10)9%.

Furthermore, among the electrolytes having the compositions shown in Table 1, Example 2 and Example 4
- Rating 400 impregnated with Example 6, Conventional Examples 1 to 3
A high-temperature load test and a high-temperature no-load test were conducted using 20 electrolytic capacitors each having a voltage of 1100 μF. The high temperature load test conditions are a temperature of 105° C., an applied voltage of 400 cm, and a standing time of 1000 hr. Further, the high temperature no-load test conditions are a temperature of 105° C. and a standing time of 1000 hr. The measurement results are shown in Table 2.

Margin below.

(11) (12) As is clear from Table 2, the initial capacitance was 105 to 111 μF for NOI to NO4 impregnated with the electrolytic solution of the example, and 97.1 to 98 μF for NO5 to NO7 impregnated with the conventional example. 3μ
F, and the former is about 1.07 to 1.14 times the latter. In addition, regarding the characteristics after the high temperature load test, the capacitance change rate is -1, 2 to -2, 9 for N01 to NO4.
%, NO5 to NO7 are -7.3 to -10.9, and the former is suppressed to about 11% to 27% of the latter. Tan δ is also about 1°02 to 1.0° for NO1 to NO4 compared to the initial value.
22 times, NO5 to NO7 about 1.24 to 1.45 times, and the former shows less deterioration. And the leakage current is NO1
~NO4 is 5.1~5゜9μA, N05~N07 is 11
．． 0 to 15.5 μA, the former being about 33% of the latter.
It can be suppressed to ~54%. Furthermore, in the high temperature no-load test, the capacitance change rate was -1 for NO1 to NO4, and 1 to -
2.3%, NO5 to NO7 is -8.5 to -10°5%, and the former is about 10% to 27% of the latter, and the change is low. Tan δ is approximately 0.98 to 1.20 times N for NO1 to NO4 (13) compared to the initial value.

5 to N07 is about 1.29 to 1.59 times, and the former is lower. Leakage current is 189 to 211 μ for NOI to NO4
A, NO5 to NO7 are 638 to 710 μA, and the former is about 27% to 33% of the latter.

(Effects of the Invention) As described above, according to the present invention, by adding guanidine phosphate or guanylurea phosphate, when impregnated into an electrolytic capacitor, the capacitance characteristics, tan δ characteristics,
An electrolytic solution for electrolytic capacitors that can improve leakage current characteristics is obtained.

Claims (1)

[Claims] (1) An electrolytic capacitor in which at least one type of guanidine phosphate or guanylurea phosphate is dissolved in an electrolytic solution for electrolytic capacitors in which 1,6-decanedicarboxylic acid or its salt is dissolved in a solvent mainly composed of polyhydric alcohol. electrolyte solution.