JPH03187210A - Electrolytis solution for driving electrolytic capacitor - Google Patents

Abstract

PURPOSE:To maintain stable characteristics of low loss at a high temperature and to acquire high reliability by dissolving choline phthalate or choline maleate as solute to polar organic solvent which contains gamma-butyrolactone and methylcellosolve. CONSTITUTION:Choline phthalate or choline maleate is dissolved as solute to polar organic solvent containing gamma-butyrolactone and methylcellosolve. In this case, since polar organic solvent containing gamma-butyrolactone and methylcellosolve is used as electrolytic solution, viscosity does not increase at a low temperature, thereby eliminating a defect of reduction of electrostatic capacity. Furthermore, since choline phthalate or choline maleate is used as solute, change of resistivity to change of temperature is small, thereby eliminating increase of loss at a high temperature. Therefore, if the electrolytic solution is used, an electrolytic capacitor can be obtained, which has stable high characteristics over a wide temperature range.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electrolytic solution for driving an electrolytic capacitor.

[Prior Art] Conventionally, electrolytes for driving electrolytic capacitors include those that use an ethylene glycol solvent and an organic acid such as boric acid or adipic acid or a salt thereof as a solute. The disadvantage is that the viscosity increases significantly.

On the other hand, to improve this drawback, N,N-dimethylformamide and γ-
There is an electrolytic solution for driving an electrolytic capacitor that uses butyrolactone as a main solvent and an amine salt of maleic acid or phthalic acid as a solute.

However, in such an electrolytic solution for driving an electrolytic capacitor, the amine salt of maleic acid or phthalic acid as a solute is chemically unstable and easily isomerized, so it cannot be used particularly at high temperatures such as 105°C. This has the disadvantage that the specific resistance of the electrolyte increases and the loss of the electrolytic capacitor increases.

In addition, as seen in Special Vehicle No. 1-171222, there are examples of dissolving choline salts of phthalic acid or maleic acid in γ-butyrolactone alone, and dissolving choline salts in a mixed solvent of γ-butyrolactone and ethylene glycol. However, when using γ-butyrolactone alone, there is a problem in that the resistivity is large, and when mixed with ethylene glycol, the viscosity of the solvent at low temperatures increases significantly, resulting in poor low-temperature properties such as increased loss and decreased capacitance. - I couldn't say it was a minute.

[Problems to be solved by the invention] - [As mentioned in 1., conventional electrolytic solutions for driving electrolytic capacitors suffer from problems such as an increase in viscosity by 1 at low temperatures and an increase in loss due to an increase in specific resistance at high d4. It had drawbacks.

The present invention was proposed to solve the problems of the prior art, and its purpose is to provide an excellent electrolytic solution for driving an electrolytic capacitor, which has low loss and
The objective is to contribute to the realization of highly reliable electrolytic capacitors that can maintain stable characteristics at high temperatures.

[Means for Solving the Problems] The electrolytic wave for driving an electrolytic capacitor according to the present invention is characterized in that choline phthalate or choline maleate is dissolved as a solute in a polar organic solvent containing γ-butyrolactone and methyl cellosolve. There is.

In this case, the concentration of choline phthalate or choline maleate in the solvent is preferably 1 to 50% by weight.

Further, the polar organic solvent containing γ-butyrolactone and methyl cellosolve is preferably a mixture of 50 to 95% by weight of γ-butyrolactone and 5 to 50% by weight of methyl cellosolve.

[Made by JTI] The electrolytic solution for driving an electrolytic capacitor of the present invention having the above structure uses a polar organic solvent containing γ-butyrolactone and methyl cellosolve, so that the viscosity increases at low temperatures. In addition, since choline phthalate or choline maleate is used as a solute, the change in resistivity due to temperature changes is small, and loss increases at high temperatures. It's fleeting. Therefore, by using the electrolytic solution for driving an electrolytic capacitor of the present invention, it is possible to provide an electrolytic capacitor having stable and high characteristics over a wide temperature range.

[Example] Examples of the electrolytic solution for driving an electrolytic capacitor of the present invention will be specifically described below with reference to FIGS. 1 and 2.

First, FIG. 1 shows γ-butyrolac! as a premise for explaining the electrolyte according to the present invention.・The mixing ratio of the solvent (γ-butyrolactone) and the solute when using choline phthalate or choline maleate as the solute,
It is a graph showing the relationship of specific resistance at 25°C. In the diagram■
When using choline phthalate as the solute, ■
This is a surface line showing the case where choline maleate is used, and the numbers at the top of the horizontal axis indicate the weight percent of the solute, and the numbers at the bottom indicate the weight percent of the solvent (γ-butyrolactone).

That is, in FIG. 1, the mixing ratio of solute and solvent (solute and two solvents) is sequentially from the left end to the right (0% by weight:
100% by weight), (10% by weight: 90% by weight), (20% by weight)
Weight %: 80 weight %), (30 weight % near 0 weight %),
(40% by weight: 60% by weight) and (50% by weight: 50% by weight), and the specific resistance of the electrolytic solution at each of these mixing ratios is shown on the vertical axis.

As is clear from Figure 1, regardless of whether choline phthalate or choline maleate is used as a solute, the resistivity remains at a constant value when the amount of solute added is 20% by weight or more. It is maintained.

Next, in Figure 2, the amount of choline phthalate or choline maleate is fixed at 20% by weight, and the amount of choline maleate is fixed at 20% by weight. It is a graph showing the relationship between the change in the mixing ratio of the solvent and the specific resistance at 25° C. using γ~butyrolactone and methyl cellosolve. In this figure 2,
The numbers at the top of the horizontal axis indicate the weight percent of methyl cellosolve, and the numbers at the bottom indicate the weight percent of γ-butyrolactone.

That is, in FIG. 2, the mixing ratio of methyl cellosolve and γ-butyrolactone (methyl cellosolve: γ-butyrolactone) is gradually increased from the left end to the right (0% by weight).
:100% by weight), (10% by weight: 90% by weight), (2
0 weight%: 80 weight%), (30 weight% near 0 weight%)
, (40% by weight: 60% by weight), (50% by weight: 50% by weight), and the specific resistance of electrolytic LTL for each of these mixing ratios is shown on the vertical axis. In FIG. 2, as in FIG. 1, ``■'' indicates the case where choline phthalate is used as the solute, and ▪ indicates the case where choline maleate is used as the solute.

As is clear from Figure 2, the specific resistance is γ
- lower than when butyrolactone is used alone. That is, as shown in ■ in each figure, when choline phthalate is used as a solute, γ-butyrolac!・When only N is used as a solvent, the resistivity exceeds 200, whereas when methyl cellosolve is mixed with the solvent, the resistivity is over 200.
00 or less, and it decreases to about 150 at the lowest. Furthermore, as shown in ■ in each figure, when choline maleate is used as the solute, the resistivity exceeds 100 when only γ-butyrolactone is used as the solvent, whereas when methyl cellosolve is used as the solvent, the resistivity exceeds 100. When mixed, the specific resistance decreases to at least about 100. In particular, when the mixing ratio of γ-butyrolactone and methyl cellosolve is 70% by weight: 30% by weight, the specific resistance is the lowest.

Next, seven types of electrolytes according to the prior art and two types of electrolytes according to the present invention were used at composition ratios as shown in Table 1 below, and the electrolytes were heated at the same rating (50V-470μF). When nine types of aluminum electrolytic capacitors (conventional ratios 1 to 7, Examples 1 and 2) differing only in composition were manufactured and various characteristics were investigated, the results shown in Tables 2 and 3 were obtained. It was done.

In this case, Table 2 shows the resistivity on each side at 25°C and -55°C. Table 3 shows the characteristics of capacitance (μF), tangent of loss angle (tanδ), and leakage current (μA), and shows the initial characteristics and the
The graph shows the characteristics after the rated voltage application test for hours.

In Table 1, EG represents ethylene glycol, GBL represents γ-butyrolactone, and MG represents methyl cellosolve.

As is clear from Table 6 of ``1,'' the aluminum electrolysis of Examples 1 and 2 using an electrolytic solution prepared by dissolving choline phthalate or choline maleate in a solution containing γ-butyrolactone and methyl cellosolve as a solvent. In the capacitor, compared to Conventional Examples 1 to 7 using other electrolytes, the specific resistance at low temperature (-55°C) is lower, and the tangent of the loss angle of the initial characteristic at 25°C is smaller. In particular, the values of the tangent of the loss angle after a 2000 hour rated voltage application test at high temperature (105°C) were 0.040 and 0.04.
5, which is much lower than the conventional values of 0.068 to 0.130, and it can be seen that the aluminum electrolytic capacitor of this example can maintain stable characteristics even at high temperatures.

In addition, as shown in Table 3, the capacitance after the voltage application test at high temperature is 22 μF ~ 22 μF compared to the initial characteristics.
Compared to the conventional example, which shows a large decrease of 70μF,
In this example, 5 μF to 7 μF compared to the initial characteristics.
, only a very slight decrease is observed, and stable capacitance can be maintained even at high temperatures.

Furthermore, as shown in Table 3, the leakage current in this embodiment is slightly lower than that in the conventional example.

On the other hand, in addition to the above Example 1.2, similar tests were conducted with different composition ratios, and similarly excellent properties were obtained.

In the present invention, the concentration of choline phthalate or choline maleate dissolved in the solvent as a solute can be selected as appropriate, but the amount added is preferably in the range of at least 1 to 50% by weight. Furthermore, the mixing ratio of the polar organic solvent containing γ-butyrolactone and methyl cellosolve can be selected as appropriate; of at least 5
It is desirable that the content be within the range of ~50% by weight.

[Effects of the Invention] As explained above, by using the electrolytic solution for driving an electrolytic capacitor according to the present invention, the loss is lower than when using a conventional electrolytic solution, and stable characteristics are maintained even at high temperatures. We can provide highly reliable and excellent electrolytic capacitors.

[Brief explanation of drawings]

FIG. 1 shows, as a premise for explaining the electrolyte according to the present invention,
It is a graph showing the relationship between the mixing ratio of the solvent and the solute and the specific resistance at 25° C. when only γ-butyrolactone is used as the solvent and choline phthalate or choline maleate is used as the solute. Figure 2 shows the relationship between the mixing ratio of γ-butyrolactone and methyl cellosolve and the specific resistance at 25°C when the solute concentration is constant and the solvent mixing ratio is changed as an example of the electrolyte according to the present invention. This is a graph showing. Patent Applicant Marcon Electronics Co., Ltd. Figure 00 0 First 0 0 5゜ (γ-acyrolactone -t, to) Figure 00 0 □□□ 0 0 0 (r-r tyrolactone ωZ〆)

Claims (3)

[Claims] (1) An electrolytic solution for driving an electrolytic capacitor, characterized in that choline phthalate or choline maleate is dissolved as a solute in a polar organic solvent containing γ-butyrolactone and methyl cellosolve. (2) The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the concentration of choline phthalate or choline maleate is 1 to 50% by weight. (3) The polar organic solvent containing γ-butyrolactone and methyl cellosolve is a mixture of 50 to 95% by weight of γ-butyrolactone and 5 to 50% by weight of methyl cellosolve. Electrolyte for driving electrolytic capacitors.