JPS62268121A - Electrolyte for electrolytic capacitor - 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] (Industrial application field) The present invention relates to an electrolytic solution for electrolytic capacitors.

(Prior Art) The electrolytic solution used in electrolytic capacitors made of aluminum or the like usually has a composition of ethylene glycol as a main solvent, to which various solutes and additives are added.

By the way, an electrolytic solution in which a dicarboxylic acid with a side chain such as 1,6-decanedicarboxylic acid or a linear dicarboxylic acid with 7 or more methylene groups (-CH2) such as azelaic acid and sebacic acid is dissolved as a solute is , has a high spark voltage of 400 V or more, and has conventionally been used as a medium-high voltage electrolyte.

(Problems to be Solved by the Invention) However, capacitors using this electrolyte have a low initial capacitance, and also have the drawback that the capacitance decreases even in high-temperature load tests.

An object of the present invention is to provide an electrolytic solution for an electrolytic capacitor that can improve the above-mentioned drawbacks and improve the capacitance characteristics of the capacitor.

(First Step to Solve the Problems) In order to achieve the above object, the present invention uses ethylene glycol as the main solvent and adds polyethylene glycol to an electrolyte solution for electrolytic capacitors containing dicarboxylic acid or its salts. The present invention provides an electrolytic solution for an electrolytic capacitor characterized by the following.

(Function) According to the present invention, since polyethylene glycol is added, the electrolytic solution comes into good contact with the electrode foil due to its surface active action, which reduces the initial capacitance characteristics of the capacitor and the capacitance during high temperature load tests. Characteristics can be improved.

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

Using ethylene glycol as a solvent, 1. as a solute.
6-decanedicarboxylic acid, ammonium azelate,
Ammonium sebacate or the like is used, and polyethylene glycol is added to it to form an electrolyte.

The weight ratio (vt%) of the components of each composition is as follows.

Example 1: (Specific resistance 550Ωcs/30°C, spark generation voltage 470V) Ethylene glycol
691.6-decanedicarboxylic acid 1
028% ammonia water 1 Polyethylene glycol (molecular weight 400) 20 Example 2:
(Specific resistance 600Ωon/30℃, spark generation voltage 480V
) Ethylene glycol 691.6
-Decanedicarbone 1 1028% ammonia water 1 Polyethylene glycol (molecular ff 1600) 20 Example 3: (Specific resistance 450Ωon/30°C, spark generation voltage 450V) Ethylene glycol 70 Ammonium azelaate 8 Pure water
2 Polyethylene glycol (molecule ff1200) 20
Example 4: (Specific resistance 640Ωczt/30°C, spark generation voltage 465V) Ethylene glycol
64 Ammonium sebacate
4 Pure water 2 Polyethylene glycol (molecule ff1200) 30
Example 5: (Specific resistance 8500cm/30°C, spark generation voltage 500v) Ethylene glycol
691.6-Decanedicarbone W1 10
28% ammonia water 1 polyethylene glycol (molecule 11000) 20 Moreover, in order to compare with each of the above examples, a conventional example consisting of the following composition components is used.

Conventional example 1: (Resistivity 800Ωcs/30℃, spark generation voltage 460V) Ethylene glycol
80 Ammonium borate 20 Conventional example 2: (Specific resistance 500Ωc11/30°C, spark generation voltage 455V) Ethylene glycol
891.6-decanedicarboxylic acid 1028
% Ammonia water 1 Conventional example 3: (
Specific resistance 430Ωcys/30℃, spark generation voltage 430
V) Ethylene glycol 90 Ammonium azelate 8 Pure water
2 Conventional example 4: (Specific resistance 580Ωcx/30℃, spark generation voltage 440V) Ethylene glycol '93 Ammonium sebacate 5 Pure water
2 Initial capacitance and high-temperature load conditions for aluminum electrolytic capacitors with a rating of 350 V and 1000 μF in which the capacitor element is impregnated with each of the electrolytes of Examples 1 to 4 and Conventional Examples 1 to 4! When the capacitance and its rate of change were measured (at temperatures of 90° C. and 110° C., and for 1000 hours), the results shown in the table were obtained.

Table As is clear from this table, according to the present invention, the initial capacitance almost satisfies the rating, and the capacitance after the high temperature load test is 0.
The rate of change from the initial value is -0°1 to 0.4 (%),
has become more or less constant. On the other hand, the conventional example is conventional example 1.
LJ, the initial capacitance is 68 to 80 (μF) higher than the rated value.
) is low, and the value after high temperature load test is -13,3 to -23
, 5 (%), and especially in Conventional Example 1, the explosion-proof valve was activated.

In addition, in an electrolytic solution consisting of ethylene glycol, 10 wt% 1,6-decanedicarbone H, 1 wt% 28% aqueous ammonia, and polyethylene glycol, the spark generation voltage and specific resistance were determined when the amount of polyethylene glycol added was changed. The results shown in FIGS. 1 and 2 were obtained. From FIG. 1, it can be seen that the spark generation voltage increases by adding polyethylene glycol. Furthermore, from FIG. 2, it can be seen that when the amount added exceeds 50%, the resistivity increases rapidly, so it is preferable that the amount is 50% or less.

In addition, FIG. 3 shows ethylene glycol 6gwt%, 1.
The results of calculating the spark generation voltage when the molecular weight of polyethylene glycol was changed for an electrolytic solution consisting of 10 wt % of 6-decanedicarbone M, 1 wt % of 28% aqueous ammonia, and 20 x #t % of polyethylene glycol are shown. As is clear from this figure, the greater the molecular weight of polyethylene glycol, the higher the spark generation voltage. However, the molecular weight of polyethylene glycol is 100
If it is 0 or more, it becomes solid at room temperature, so it is preferably less than 1000, and if it is less than 200, the effect is low, so 2
00 or more is preferable.

(Effects of the Invention) As described above, according to the present invention, since polyethylene glycol is added as an additive, the initial capacitance and the rate of capacitance change after a high temperature load test can be improved due to its surface active action. Furthermore, an electrolytic solution for electrolytic capacitors having a high spark generation voltage can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a graph of spark generation voltage versus the amount of polyethylene glycol added, FIG. 2 is a graph of specific resistance versus the amount of polyethylene glycol added, and FIG. 3 is a graph of spark generation voltage versus the molecular weight of polyethylene glycol. Patent applicant: Hitachi Capacitor Co., Ltd.

Claims (3)

[Claims] (1) An electrolytic solution for an electrolytic capacitor that uses ethylene glycol as a main solvent and contains a dicarboxylic acid or a salt thereof, which is characterized in that polyethylene glycol is added thereto. (2) The molecular weight of polyethylene glycol is 200-10
The electrolyte solution for an electrolytic capacitor according to claim 1, which is 00. (3) The electrolytic solution for an electrolytic capacitor according to claim 1, wherein the amount of polyethylene glycol added is 50 wt% or less.