JP3254981B2 - Electrolyte for electrolytic capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for an electrolytic capacitor.

[0002]

2. Description of the Related Art An electrolytic capacitor such as an aluminum electrolytic capacitor generally has a capacitor element impregnated with an electrolytic solution.
This electrolytic solution is particularly used for medium and high pressures, for example, using a polyhydric alcohol such as ethylene glycol as a solvent, and adding adipic acid, suberic acid, azelaic acid, linear aliphatic dicarboxylic acid such as sebacic acid or the like. Has been dissolved as a solute.

[0003] In recent years, there has been an increasing demand for reducing the loss of aluminum electrolytic capacitors. One of the effective means for reducing the loss of the aluminum electrolytic capacitor is to lower the specific resistance of the electrolytic solution.

[0004]

However, the conventional electrolytic solution using a polyhydric alcohol and an aliphatic straight-chain dicarboxylate causes an ester reaction at a high temperature, so that the specific resistance tends to increase. is there. Therefore, in an electrolytic capacitor using this electrolytic solution, tan δ increases, and it is difficult to improve the life.

An object of the present invention is to provide an electrolytic solution for an electrolytic capacitor which can improve the above-mentioned disadvantages, has a low specific resistance, can improve the tan δ characteristics of the electrolytic capacitor, and can prolong the life.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an electrolytic solution for an electrolytic capacitor containing a polyhydric alcohol as a main solvent, comprising 2-ethenyl-5-methylbenzene.
Luadipic acid, 2-ethenyl-6-methylpimelic acid,
2-ethenyl-7-methylsuberic acid, 2-ethenyl-
8-methylazelaic acid, 2-ethenyl-9-methylse
Basic acid, 2-ethenyl-9-ethylsebacic acid, 2-
It is intended to provide an electrolytic solution for an electrolytic capacitor, characterized by dissolving a dicarboxylic acid selected from ethynyl-9- ethylsebacic acid or a salt thereof.

Polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, 1,4
Using butanediol, glycerin and the like;

[0008] 2-ethenyl-5-methyladipin
The dissolution amount of an acid, dicarboxylic acid such as 2-ethenyl-6-methylpimelic acid or a salt thereof is preferably in the range of 1 to 30% by weight.
That is, when the amount of dissolution is less than 1% by weight, the effect of lowering the specific resistance is low.

[0009]

Action 2-Ethenyl-5-methyladipate, 2-E
Dicarboxylic acids such as tenyl-6-methylpimelic acid ,
Since the α-carbon of the main chain has an aliphatic hydrocarbon group such as a methyl group, an esterification reaction with a polyhydric alcohol hardly occurs at a high temperature. Therefore, even if the electrolytic capacitor using the electrolytic solution in which the dicarboxylic acid is dissolved is used for a long time at a high temperature, the specific resistance of the electrolytic solution does not easily increase.
nδ can be prevented from significantly increasing.

Also, 2-ethenyl-5-methyladipin
Acids and dicarboxylates such as 2-ethenyl-6-methylpimelic acid have side chains, so that they are more versatile than linear dicarboxylic acids such as azelaic acid and sebacic acid. It is easily soluble in polyhydric alcohols, has excellent low-temperature characteristics, can lower the specific resistance, and can increase the spark generation voltage.

Further, 2-ethenyl-5-methyladipi
Acids, dicarbonic acids such as 2-ethenyl-6-methylpimelic acid, and the like are difficult to form a complex with the anode foil because of their unique molecular structures. Therefore, the capacity of the electrolytic capacitor can be reduced.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
Polyhydric alcohol with ethylene glycol, which is referred to as solvent. The dicarboxylic acid is 2-ethenyl-5-
Methyl adipic acid, 2-ethenyl-6-methylpimelin
Acid, 2-ethenyl-7-methylsuberic acid, 2-ethenyl
Ru-8-methylazelaic acid, 2-ethenyl-9-methyl
Lucevanic acid, 2-ethenyl-9-ethylsebacic acid,
Use 2-ethynyl-9-ethylsebacic acid . Then, aqueous ammonia is dissolved in these solutions to convert the dicarboxylic acid into an ammonium salt.

Next, with respect to the electrolyte solutions of the examples having the compositions shown in Tables 1 and 2, and the conventional electrolyte solution shown in Table 3,
Each specific resistance was measured after being left for 2,000 hours in an atmosphere at a temperature of 130 ° C. The temperature during the measurement is 30 ° C.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

As is apparent from Tables 1 to 3, in Examples 1 to 7 , the initial value is 296 to 467 Ω · cm, and the value after standing is 569 to 609 Ω · cm. On the other hand, in Conventional Examples 1 to 5, the initial value is 330 to 494 Ω · cm, and the value after standing is 834 to 1,080 Ω · cm. That is,
After leaving for 2,000 hours, Examples 1 to 7
Approximately 52.7 to 73.0 compared to Conventional Examples 1 to 5.
%.

The initial characteristics and the characteristics after the high-temperature load test were measured for a rated 250 V, 330 μF aluminum electrolytic capacitor impregnated with each of the electrolytic solutions having the compositions shown in Tables 1 to 3. The high-temperature load test is performed by continuously applying a rated voltage and leaving it in an atmosphere at a temperature of 130 ° C for 2,000 hours. The number of samples is 20 each. The measured values were average values and are shown in Table 4.

[0019]

[Table 4]

As is clear from Table 4, the initial characteristics of Examples 1 to 7 were tan δ 0.033.
～0.053, leakage current 41 ～52Myuei and Conventional Example 1
Tan δ 0.036 to 0.059 and leakage current 60 to 65 μA in the case of Conventional Example 5. That is, in the case of Examples 1 to 7 , the tan δ is lower as a whole and the leakage current is about 63.1 to 8 compared to the cases of Conventional Examples 1 to 5.
It is 6.7% in size.

Further, after the high-temperature load test, the cases of Examples 1 to 7 show that the capacitance change rate is -1.0 to -3.2%,
tan δ 0.064 to 0.069 and leakage current 8 to 9 μA. In the case of Conventional example 1 to Conventional example 5, the capacitance change rate was -4.2 to -9.8%, tan δ 0.091 to 0.1.
30, a leakage current of 16 to 18 μA. That is, when the first to seventh embodiments are used, the capacitance change rate is about 10.2 to 7 as compared with the first to fifth examples.
6.2%, and tan δ is about 49.2 to 75.8
%, And the leakage current is about 44.4 to 56.3%.

[0022]

According to the present invention, 2-ethenyl-5-meth
Tildipic acid, 2-ethenyl-6-methylpimelin
Acid, 2-ethenyl-7-methylsuberic acid, 2-ethenyl
Ru-8-methylazelaic acid, 2-ethenyl-9-methyl
Lucevanic acid, 2-ethenyl-9-ethylsebacic acid,
Since dicarbonic acid or a salt thereof selected from 2-ethynyl-9-ethylsebacic acid is dissolved, the specific resistance is low, the temperature is stable to high temperatures, and the tan of the electrolytic capacitor is low.
An electrolytic solution for an electrolytic capacitor that can improve δ characteristics, leakage current characteristics, and high-temperature characteristics and can prolong its life can be obtained.

Claims (1)

(57) [Claims] 1. An electrolytic solution for an electrolytic capacitor comprising a polyhydric alcohol as a main solvent, comprising: 2-ethenyl-5-methyl
Adipic acid, 2-ethenyl-6-methylpimelic acid, 2
-Ethenyl-7-methylsuberic acid, 2-ethenyl-8
-Methylazelaic acid, 2-ethenyl-9-methylseba
Synic acid, 2-ethenyl-9-ethylsebacic acid, 2-E
An electrolytic solution for an electrolytic capacitor, wherein a dicarboxylic acid selected from tinyl-9-ethylsebacic acid or a salt thereof is dissolved.