JP2002270472A - Electrolytic capacitor and electrolytic solution therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic capacitor which has high conductivity, a high spark voltage, and superior low-temperature stability, and an electrolytic solution for the electrolytic capacitor which has superior capacitor characteristics, superior low-temperature and high-temperature stability, and improved life. SOLUTION: This electrolytic solution for the electrolytic capacitor is obtained by incorporating at least one electrolyte selected from a group of dicarboxylic acid and its amine salt, having cyclobutane in its structure skeleton and shown by general formula <I>, and an organic polar solvent, and the electrolytic capacitor is formed by using the electrolytic solution. Here, R1 and R2 are alkali groups with carbon number of 1 to 3, and R3 is an alkyl group with an atomic hydrogen or carbon number of 1 to 3.

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 and an electrolytic capacitor manufactured using the electrolytic solution.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 31-8971 discloses an electrolytic solution for electrolytic capacitors in which boric acid or a salt thereof as an electrolyte is dissolved in an organic polar solvent such as ethylene glycol. Electrolyte for capacitors has low conductivity, and water is generated by esterification of boric acid and ethylene glycol.At high temperatures, water vapor is generated and the internal pressure rises, causing damage to the outer case of the electrolytic capacitor. There were drawbacks.

In order to improve the above disadvantage, Japanese Patent Publication No. Sho 47-3
No. 0461 discloses that a straight-chain alkyldicarboxylic acid such as azelaic acid and sebacic acid or a salt thereof is used as an electrolyte. The linear alkyl dicarboxylic acid has low solubility in organic polar solvents, and tends to precipitate crystals at room temperature or lower, deteriorating the characteristics of the electrolytic capacitor at low temperatures.

For the purpose of improving the characteristic deterioration at low temperatures, Japanese Patent Publication Nos. 60-13293 and 63-15738 disclose butyl octane diacid, 5,6-decane dicarboxylic acid and the like as electrolytes. It is disclosed that a branched alkyldicarboxylic acid or a salt thereof is used. A branched alkyldicarboxylic acid or a salt thereof has high solubility in an organic polar solvent, and can suppress deterioration of characteristics of an electrolytic capacitor at a low temperature. In addition, since the esterification reaction between the branched alkyldicarboxylic acid or a salt thereof and ethylene glycol is slow, the generation of water is small,
The electrolyte at a high temperature can be stabilized.

However, when used at a high temperature for a long time, even a branched alkyldicarboxylic acid is adsorbed on the surface of the electrode foil and forms a complex there, so that the electrostatic capacity (hereinafter, referred to as the capacitance) is increased.
It is described as “Cap”. ) Decreases and the tangent of the loss angle (hereinafter, referred to as “tan δ”) greatly increases.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrolytic solution for an electrolytic capacitor which has high conductivity, high spark voltage, and excellent low-temperature stability, and has excellent capacitor characteristics. Another object of the present invention is to provide a highly reliable electrolytic capacitor having excellent low-temperature and high-temperature stability and having an improved capacitor life.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, have found that a dicarboxylic acid having a specific structure having cyclobutane in a structural skeleton or an amine salt thereof is used as an electrolyte. The inventors have found that the above-mentioned problems can be solved, and have completed the present invention.

That is, the present invention relates to an organic polar solvent comprising at least one electrolyte selected from the group consisting of dicarboxylic acids or amine salts thereof having a cyclobutane in a structural skeleton and represented by the following general formula <I>: And an electrolytic solution for an electrolytic capacitor, characterized by being prepared by using the electrolytic solution.

[0009]

Embedded image

In the formula, R ₁ and R ₂ each represent an alkyl group having 1 to 3 carbon atoms, and R ₃ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

R ₁ , R ₂ and R ₃ have 1 to 1 carbon atoms
Examples of the alkyl group 3 include a methyl group, an ethyl group, and a propyl group.

In the amine salt of the dicarboxylic acid represented by the general formula <I>, the amine serving as the cation component is selected from the group consisting of known ammonia, primary amine, secondary amine, tertiary amine and quaternary ammonium. At least one selected from them is given.

The organic polar solvent used in the present invention includes ethylene glycol, γ-butyrolactone, etc., which are generally used as a solvent for an electrolytic solution for an electrolytic capacitor.
A known organic polar solvent can be used.
More than one species is used.

The dicarboxylic acid represented by the general formula <I> having cyclobutane in the skeletal structure and used as an electrolyte in the present invention is, for example, prepared by using α-pinene or γ-pinene as a raw material, a nitric acid oxidation method, an ozone It can be synthesized by a method of oxidative cleavage of a double bond such as an oxidation method.

After dissolving the previously synthesized dicarboxylic acid represented by the general formula <I> in water, adding a known amine appropriately selected to cause a neutralization reaction, and then dehydrating under reduced pressure. Thus, the desired amine salt of dicarboxylic acid is obtained.

The dicarboxylic acid or the amine salt thereof represented by the general formula <I> used in the present invention is usually 1 to 60 parts by mass with respect to the total mass of the electrolytic solution for an electrolytic capacitor.
Preferably it is 5 to 40 parts by mass. As the other electrolyte, a known organic acid or a salt thereof may be used in combination. In this case, even if the dicarboxylic acid or the amine salt thereof represented by the above general formula <I> is less than 5 parts by mass, it is used alone. In this case, an electrolytic capacitor having characteristics equivalent to 5 parts by mass can be obtained.

The electrolytic solution for an electrolytic capacitor of the present invention may contain a polyhydric alcohol such as mannitol or sorbite, a nonionic surfactant, or the like, if necessary, in order to increase the withstand voltage, or to prevent corrosion. A nitro compound or the like is added.

The dicarboxylic acid or the amine salt thereof represented by the above general formula <I> has an alicyclic cyclobutane in the structural skeleton as compared with a conventional linear alkyldicarboxylic acid or a branched alkyldicarboxylic acid or a salt thereof. As a result, the solubility in the organic polar solvent is very high.

The electrolytic solution for electrolytic capacitors using the dicarboxylic acid or the amine salt thereof represented by the general formula <I> as an electrolyte has a high conductivity and a high spark voltage, and does not precipitate crystals even at a low temperature. An electrolytic capacitor manufactured using an electrolytic solution has excellent low-temperature stability.

The dicarboxylic acid represented by the general formula <I> or the amine salt thereof has a three-dimensional structure, and the dicarboxylic acid represented by the general formula <I> or the amine salt thereof is The electrolytic solution for the electrolytic capacitor used as the electrolyte is
A capacitor that hardly forms a complex with the electrode foil and has a small decrease in Cap can be obtained.

The dicarboxylic acid represented by the general formula <I> hardly causes an esterification reaction with ethylene glycol due to steric hindrance, so that deterioration of the electrolytic solution can be suppressed even at a high temperature. The electrolytic capacitor manufactured by using this is excellent in stability at high temperature.

The electrolytic capacitor of the present invention, which is produced using an electrolytic solution for an electrolytic capacitor using a dicarboxylic acid or an amine salt thereof represented by the general formula <I> as an electrolyte, has excellent capacitor characteristics, This is a highly reliable capacitor with excellent stability at high temperatures and improved capacitor life.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples. In the examples, “parts” represents “parts by mass”. The present invention is not limited to these examples.

Example 1 First, in a dicarboxylic acid represented by the general formula <I>,
A dicarboxylic acid in which R ₁ and R ₂ are methyl groups and R ₃ is a hydrogen atom (hereinafter, referred to as “dicarboxylic acid A”).
Was synthesized.

Next, an electrolyte was prepared by mixing 15 parts of the ammonium salt of dicarboxylic acid A as an electrolyte with 84 parts of ethylene glycol as an organic polar solvent and 1 part of water. Table 1 shows the composition of the prepared electrolyte solution. The conductivity of the electrolyte at a temperature of 30 ° C. is 1.
It was 86 mS / cm, and the spark voltage at a temperature of 85 ° C. was 510 V. Table 2 shows the results.

Further, the temperature is -20.degree. C., -40.degree.
After cooling to ℃, the presence or absence of the precipitation of crystals was visually confirmed, and a low-temperature solubility test of the electrolytic solution was performed. As a result, no crystals were precipitated at each temperature. Table 2 shows the results.

An electrolytic capacitor having a rated voltage of 400 V and a rated capacity of 9.0 μF was prepared using the electrolytic solution. The initial value of the obtained electrolytic capacitor is such that Cap is 9.2 μF, t
an δ was 0.047. In a high-temperature load test in which a rated voltage of 400 V was applied at a temperature of 105 ° C. and 1000 hours passed, the rate of change in Cap was −1.3%, tan δ
Was 0.055. Table 3 shows the results.

Example 2 Ammonium salt 40 of dicarboxylic acid A used in Example 1
The mixture was mixed with 59 parts of an organic polar solvent, ethylene glycol, and 1 part of water to prepare an electrolytic solution for an electrolytic capacitor. Table 1 shows the composition of the prepared electrolyte solution. The conductivity of the electrolyte at a temperature of 30 ° C. is 2.41 m.
S / cm, and the spark voltage at a temperature of 85 ° C. is 505.
V. Table 2 shows the results. In addition, in the low-temperature solubility test performed in the same manner as in Example 1, the temperature-
No crystals were precipitated up to 60 ° C. Table 2 shows the results.

An electrolytic capacitor similar to that of Example 1 was manufactured using the electrolytic solution. The initial values of the obtained electrolytic capacitor were Cap of 9.2 μF and tan δ of 0.046. In the high temperature load test, the Cap change rate was -1.
4%, tan δ was 0.055. Table 3 shows the results.

Example 3 First, in a dicarboxylic acid represented by the general formula <I>,
A dicarboxylic acid in which R ₁ and R ₂ are methyl groups and R ₃ is a methyl group (hereinafter, referred to as “dicarboxylic acid B”).
Was synthesized.

Then, 10 parts of the ammonium salt of dicarboxylic acid B was used as an electrolyte and mixed with 89 parts of ethylene glycol as an organic polar solvent and 1 part of water to prepare an electrolytic solution for an electrolytic capacitor. Table 1 shows the composition of the prepared electrolyte solution. The conductivity of the electrolyte at a temperature of 30 ° C. is 2.
The spark voltage at a temperature of 85 ° C. was 505 V. Table 2 shows the results. In the low-temperature solubility test, no crystals were precipitated up to a temperature of −60 ° C. as in Example 1. Table 2 shows the results.

An electrolytic capacitor similar to that of Example 1 was manufactured using the electrolytic solution. The initial value of the obtained electrolytic capacitor was Cap of 9.1 μF and tan δ of 0.049. In the high temperature load test, the Cap change rate was -1.
4% and tan δ were 0.056. Table 3 shows the results.

Example 4 First, in a dicarboxylic acid represented by the general formula <I>,
A dicarboxylic acid in which R ₁ and R ₂ are ethyl groups and R ₃ is a methyl group (hereinafter, referred to as “dicarboxylic acid C”).
Was synthesized.

Then, 10 parts of the ammonium salt of dicarboxylic acid C was used as an electrolyte, and mixed with 89 parts of ethylene glycol as an organic polar solvent and 1 part of water to prepare an electrolytic solution for an electrolytic capacitor. Table 1 shows the composition of the prepared electrolyte solution. The conductivity of the electrolyte at a temperature of 30 ° C. is 1.
It was 65 mS / cm, and the spark voltage at a temperature of 85 ° C. was 525 V. Table 2 shows the results. In the low-temperature solubility test, no crystals were precipitated up to a temperature of −60 ° C. as in Example 1. Table 2 shows the results.

An electrolytic capacitor similar to that of Example 1 was manufactured using the electrolytic solution. The initial values of the obtained electrolytic capacitor were 9.1 μF for Cap and 0.048 for tan δ. In the high temperature load test, the Cap change rate was -1.
6% and tan δ were 0.057. Table 3 shows the results.

Example 5 5 parts of ammonium salt of dicarboxylic acid A used in Example 1 and ammonium salt 5 of dicarboxylic acid B used in Example 2
The mixture was mixed with 89 parts of ethylene glycol as an organic polar solvent and 1 part of water to prepare an electrolytic solution for an electrolytic capacitor. Table 1 shows the composition of the prepared electrolyte solution. The conductivity of the electrolyte at a temperature of 30 ° C. is 1.98 m.
S / cm and the spark voltage at a temperature of 85 ° C. is 505
V. In the low-temperature solubility test, no crystals were precipitated up to a temperature of −60 ° C. as in Example 1. Table 2 shows the results.

An electrolytic capacitor similar to that of Example 1 was manufactured using the electrolytic solution. The initial value of the obtained electrolytic capacitor was Cap of 9.2 μF and tan δ of 0.048. In the high temperature load test, the Cap change rate was -1.
4%, tan δ was 0.055. Table 3 shows the results.

Example 6 An electrolyte was prepared by mixing 15 parts of the diethylamine salt of dicarboxylic acid A synthesized in advance with 84 parts of ethylene glycol as an organic polar solvent and 1 part of water as an electrolyte. Table 1 shows the composition of the prepared electrolyte solution.
The conductivity of the electrolyte at a temperature of 30 ° C. is 1.45 mS /
cm, and the spark voltage at a temperature of 85 ° C. was 490 V. In the low-temperature solubility test, as in Example 1,
No crystals were precipitated until the temperature reached -60 ° C. Table 2 shows the results.

Using the electrolytic solution, an electrolytic capacitor similar to that of Example 1 was produced. The initial value of the obtained electrolytic capacitor was Cap of 9.1 μF and tan δ of 0.046. In the high temperature load test, the CAP change rate was -1.
6% and tan δ were 0.053. Table 3 shows the results.

Comparative Example 1 An electrolytic solution for an electrolytic capacitor was prepared by mixing 5 parts of ammonium azelate as an electrolyte with 94 parts of ethylene glycol as an organic polar solvent and 1 part of water. Table 1 shows the composition of the prepared electrolyte solution. The conductivity of the electrolyte at a temperature of 30 ° C. is 1.33 mS / cm, and the temperature of the electrolyte is 85 ° C.
Was 430V. In the low-temperature solubility test, crystals were precipitated at a temperature of -20 ° C.
Table 2 shows the results.

Using the electrolytic solution, an electrolytic capacitor similar to that of Example 1 was produced. The initial values of the obtained electrolytic capacitor were Cap of 9.2 μF and tan δ of 0.046. In the high temperature load test, the Cap change rate was −4.
2% and tan δ were 0.081. Table 3 shows the results.

Comparative Example 2 An electrolytic solution for an electrolytic capacitor was prepared by mixing 5 parts of ammonium sebacate as an electrolyte with 94 parts of ethylene glycol as an organic polar solvent and 1 part of water. Table 1 shows the composition of the prepared electrolyte solution. The conductivity of the electrolyte at a temperature of 30 ° C. was 1.10 mS / cm, and the spark voltage at a temperature of 85 ° C. was 450 V. In the low-temperature solubility test, crystals were precipitated at a temperature of -20 ° C.
Table 2 shows the results.

An electrolytic capacitor similar to that of Example 1 was manufactured using the electrolytic solution. The initial values of the obtained electrolytic capacitor were Cap of 9.1 μF and tan δ of 0.051. In the high temperature load test, the Cap change rate was −4.
8% and tan δ were 0.074. Table 3 shows the results.

Comparative Example 3 An electrolytic solution for an electrolytic capacitor was prepared by mixing 5 parts of ammonium 1,6-decanedicarboxylate as an electrolyte with 94 parts of an organic polar solvent, ethylene glycol and 1 part of water. Table 1 shows the composition of the prepared electrolyte solution. The conductivity of the electrolyte at a temperature of 30 ° C. was 1.34 mS / cm, and the spark voltage at a temperature of 85 ° C. was 450 V.
In the low-temperature solubility test, the solution became slightly turbid at a temperature of -60 ° C. Table 2 shows the results.

An electrolytic capacitor similar to that of Example 1 was manufactured using the electrolytic solution. The initial values of the obtained electrolytic capacitor were Cap of 9.2 μF and tan δ of 0.050. In the high temperature load test, the Cap change rate was −6.
0% and tan δ were 0.063. Table 3 shows the results.

[0046]

[Table 1]

[0047]

[Table 2]

As is clear from Table 2, the electrolytic solution for electrolytic capacitors of the present invention (Examples 1 to 6) has higher conductivity and higher spark voltage than the conventional (Comparative Examples 1 to 3). is there. In addition, in the related art (Comparative Examples 1 to 3), at a temperature of −60 ° C., slight turbidity to crystal precipitation of the electrolytic solution were observed,
Electrolytic solution for electrolytic capacitor of the present invention (Examples 1 to 6)
Has no crystal precipitation even at a temperature of −60 ° C., and is excellent in low-temperature stability.

[0049]

[Table 3]

As is evident from Table 3, the electrolytic capacitors prepared using the electrolytic solutions for electrolytic capacitors of the present invention (Examples 1 to 6) were higher in the post-high temperature load test than the conventional ones (Comparative Examples 1 to 3). Is small, the tan δ is not much different from the initial value, the capacitor life is long, and the capacitor has high reliability.

[0051]

The dicarboxylic acid or its amine salt used as an electrolyte in the present invention has cyclobutane which is an alicyclic ring in its structural skeleton, and therefore has a very high solubility in organic polar solvents. Has high conductivity and high spark voltage. Further, even at a temperature of -60 ° C, no crystals are precipitated, and the low-temperature stability is excellent.

The electrolytic capacitor of the present invention has a temperature of 105 ° C.
Even after × 1000 hours, the rate of change in Cap and the change in tan δ are small, and the stability at high temperatures is excellent.

The electrolytic capacitor of the present invention is a highly reliable capacitor having excellent capacitor characteristics, excellent stability at low and high temperatures, and having an improved capacitor life.

Claims (3)

[Claims] 1. An organic polar solvent comprising at least one electrolyte selected from the group consisting of a dicarboxylic acid represented by the following general formula <I> or an amine salt thereof having cyclobutane in a structural skeleton, and an organic polar solvent. An electrolytic solution for an electrolytic capacitor, comprising: Embedded image (Wherein, R ₁ and R ₂ represent an alkyl group having 1 to 3 carbon atoms;
R ₃ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. ) 2. The method according to claim 1, wherein the cation component of the dicarboxylic acid amine salt is at least one selected from the group consisting of ammonia, primary amine, secondary amine, tertiary amine and quaternary ammonium. The electrolytic solution for an electrolytic capacitor according to the above. 3. An electrolytic capacitor produced by using the electrolytic solution for an electrolytic capacitor according to claim 1.