JPS63224212A - 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 [Field of Industrial Application] The present invention relates to an electrolytic capacitor, and more particularly to an electrolytic capacitor using a novel driving electrolyte.

[Prior Art] Electrolytic capacitors are made by winding an anode foil and a cathode foil made of a valve metal such as aluminum together with a separator to form a capacitor element.Generally, the capacitor element f is impregnated with a driving electrolyte, and the capacitor element f is impregnated with a driving electrolyte, and the capacitor element is made of a metal case made of aluminum or the like. The capacitor element is housed in a synthetic resin case and has a sealed structure.

Conventionally, the electrolytic solution for driving such electrolytic capacitors uses a polar organic solvent such as ethylene glycol as the main solvent, and an electrolytic solution in which a salt such as an ammonium salt of a saturated organic acid that does not corrode the metal electrodes is dissolved. A liquid is generally used (Japanese Patent Publication No. 58-13019). It is also known to use a mixed solvent of γ-butyrolactone and ethylene glycol as a solvent for the electrolytic solution (Japanese Unexamined Patent Publication No. 54-7564).

[Problems to be Solved by the Invention] However, in the electrolytic solution disclosed in Japanese Patent Publication No. 58-13019, 1 to 30% by weight is added in order to lower the tangent of loss angle (tan δ), which is an index of electrical resistance. However, in this case, the characteristics of the capacitor deteriorate at high temperatures due to corrosion of the cathode foil and transpiration of dissociated ammonia (sHffi), especially changes in the tangent of the loss angle (tanδ). The problem was that it was large. In addition, as an electrolytic solution that has high electric strength (low electrical resistance) and is stable at high temperatures, the use of an electrolytic solution in which a quaternary ammonium salt of a saturated chain dicarboxylic acid is dissolved in a polar organic solvent has been disclosed in JP-A-59-78522. It is disclosed in the publication No. However, according to the examples in the same publication, the conductivity of this electrolyte is at most 9.4 mS/cm, which is insufficient compared to the currently required level (12 to 25 mS/cm). Furthermore, when γ-butyrolactone and ethylene glycol are used as a mixed solvent as seen in JP-A-54-7564, the viscosity of ethylene glycol increases at low temperatures. There was a problem in that the effect of improving the low-temperature characteristics of the capacitor was small.

The present invention solves these problems and provides an electrolytic capacitor that uses a driving electrolyte that has low electrical resistance (high i′l1t4 degrees), excellent low-temperature characteristics, and excellent high-temperature stability. The purpose is to

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention is characterized by using a driving electrolyte prepared by dissolving a quaternary ammonium salt of γ-resorcylic acid in a polar organic solvent. The present invention provides an electrolytic capacitor that has the following characteristics.

As the quaternary ammonium salt of γ-resorsilic acid used in the present invention, quaternary ammonium salts represented by the general formula R,N'' in which alkyl & (R) have 1 to 10 carbon atoms, particularly 1 to 4 For example, tetramethylammonium γ-resorcylate,
Examples include tetraethylammonium γ-resorcylate, tetrapropylammonium γ-resorcylate, and tetrabutylammonium γ-resorcylate.

In the present invention, the reason for using the quaternary ammonium salt of γ-resorsilic acid is that when Y-resorsilic acid is other amine salt, the conductivity of the electrolyte is low, and the tan δ of the product is
This is because it becomes large, which is not desirable.

The content (concentration) of the quaternary ammonium salt of γ-resorcylic acid used in the present invention in the electrolyte composition can be selected as appropriate, but considering that the specific resistance is the lowest in the state of a saturated solution, 1 ~50% by weight is suitable;
Among these, in order to obtain good high temperature stability, 5 to 40% by weight is suitable. In order to solve the above problems, the polar organic solvent used in the present invention includes at least γ-butyrolactone and 3-alkyl-1,3-oxazolidine-2-
(hereinafter referred to as A, 0.). Here, examples of the alkyl group include methyl, ethyl, propyl, etc. Among them, methyl and ethyl are preferred from the viewpoint of improving low-temperature properties.

Further, as the solvent to be mixed, any polar organic solvent commonly used in electrolytic capacitors can be used, and amides, lactones, glycols, fL yellow compounds, or carbon salts are preferably used. Specific examples of preferred miscible solvents include N,N-dimethylformamide, N-methylformamide, β-butyrolactone,
Examples of these solvents include γ-valerolactone, N-methylpyrrolidone, ethylene glycol, ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, dimethyl sulfoxide, propylene carbonate, and ethylene cyanopidrine. Alternatively, a plurality of combinations may be appropriately mixed and used.

In the present invention, in order to obtain a driving electrolyte containing a quaternary ammonium salt of γ-resorsilic acid, this quaternary ammonium salt may be added to a polar organic solvent.
- The quaternary ammonium salt of resorcilic acid may be produced by reacting a substance capable of producing the quaternary ammonium salt.

In the present invention, it is not necessary to include water in the electrolytic solution, but it is effective to lower the specific resistance. However, if the water content is increased to a certain limit, the electrolytic capacitor's case will swell due to the generation of internal gas and the electrode foil will be eroded. It is preferable that the water content be as small as possible. Therefore, depending on the purpose of use of the electrolytic capacitor, the water content in the electrolyte composition should be 0.
The range is preferably 1 to 20% by weight, and 0.5 to 15% by weight.
The range of is more preferable.

The electrolytic capacitor of the present invention includes capacitors of various embodiments. In a typical embodiment, an aluminum foil anode and an aluminum foil cathode are separated by a suitable separator such as paper, and these are wound into a cylindrical shape to form a capacitor element, and this element is impregnated with a driving electrolyte. let The α content of the electrolytic solution is preferably 50 to 300j'l1% relative to the separator. The element impregnated with the electrolyte is housed in a case made of corrosion-resistant metal, synthetic resin, or the like, and has a sealed structure.

[Examples] The present invention will be specifically described below based on Examples and Comparative Examples.

After mixing a 10% aqueous solution of tetraalkylammonium hydroxide (alkyl group has 1 to 3 carbon atoms) and γ-resorcylic acid to have an equimolar number and dissolving the γ-resorcylic acid, water is removed using an evaporator. This was removed to produce a quaternary ammonium salt of γ-resorsilic acid, which was used as a solute and a predetermined amount was dissolved in a polar organic solvent to obtain the electrolytes of Examples 1 to 8. The pH of the electrolytic solution was adjusted to 5-7.

Using these electrolytes, we manufactured an electrolytic capacitor (rated 10V, 470μF) with aluminum electrodes and conducted a high temperature load test (rated voltage applied, 125℃, 1000 hours).
The changes in the tangent of the loss angle (tan δ) were measured, and the results are shown in Table 1. In addition, Comparative Examples 1 to 4 are cases in which a substance other than the quaternary ammonium salt of γ-resorsilic acid is used, and electrolytic capacitors were manufactured in the same manner as in the example, and a high temperature load test was conducted under the same conditions as in the example. The results are shown in Table 1.

In Table 1, M, O, and E, 0. is the above-mentioned A, 0. represents methyl and ethyl alkyl groups, respectively.

Table 1 Example of electrolyte composition and high temperature load test Next, Table 2 shows the low temperature characteristics of the electrolytic capacitor. The electrolytic capacitors were the same as those described above, and the number of samples was 10 each. The measurement frequency is 120Hz. 8C/C20℃ in the table is the capacity change rate at 20℃, Z/Z
20°C indicates the impedance ratio with respect to 20°C.

Average value of n = 10 As can be seen from the table J1, in the comparative example, the change in the tangent of the prior lost angle was large in the high temperature load test, whereas in the example, this change could be made small. can.

In addition, as can be seen from Table 2, the comparative example has a large change rate of △C/C 20℃ and Z/Z 20℃ in low temperature characteristics, whereas the example aims to reduce this change rate. It is something that can be done.

[Effects of the Invention] As explained above, the present invention provides an electrolytic capacitor with excellent low-temperature characteristics and excellent high-temperature stability with small change in tangent of loss angle (tan δ) under high-temperature conditions. I can do something.

Claims (4)

[Claims] (1) An electrolytic capacitor characterized by using a driving electrolytic solution prepared by dissolving a quaternary ammonium salt of γ-resorsilic acid in a polar organic solvent. (2) In a polar organic solvent consisting of γ-butyrolactone and 3-alkyl-1,3-oxazolidin-2-one, γ-
2. The electrolytic capacitor according to claim 1, characterized in that a driving electrolyte prepared by dissolving a quaternary ammonium salt of resorlic acid is used. (3) The electrolytic capacitor according to claim 1, wherein the content of the quaternary ammonium salt of γ-resorsilic acid in the driving electrolyte is 1 to 50% by weight. (4) The electrolysis according to claim 1 or 2, wherein the alkyl group (R) of the quaternary ammonium represented by the general formula R_4N^+ has 1 to 10 carbon atoms. capacitor.