JPS62254416A - 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 applications The present invention relates to an electrolytic solution for electrolytic capacitors.

According to the present invention, an electrolytic solution for medium-high voltage electrolytic capacitors (hereinafter sometimes simply referred to as electrolytic solution) having relatively high conductivity can be obtained.

Conventionally, in electrolytic capacitors, medium-high voltage electrolyte solutions have been used in which boric acid or ammonium borate is dissolved as a solute in an ethylene glycol solvent because the spark generation voltage can be made relatively high. However, if such an electrolytic solution is used at a temperature exceeding 100°C, the package may be destroyed due to the vapor pressure of the water due to the large amount of condensed water produced by the esterification reaction between ethylene glycol and boric acid. There was a problem.

In order to improve this problem, ammonium salts of aliphatic dicarunic acids such as azelaic acid with 9 carbon atoms, sepacic acid with 10 carbon atoms, and decanedicalonic acid with 12 carbon atoms, which have a high spark generation voltage, are used as solutes. It has been proposed that
Publication No. 2).

However, these solutes have poor solubility in solvents, making it difficult to increase the conductivity of the electrolyte without adding water, and the solutes precipitate at temperatures below room temperature, deteriorating the low-temperature characteristics of capacitors. There was a problem.

Furthermore, it has been proposed to improve low-temperature properties by using linear aliphatic dicarboxylic acid or branched aliphatic dicarboxylic acid with good solubility in solvents (especially Publications No. 56-45014 and No. 57-27013).

Since all of the above electrolytes use solvents mainly consisting of ethylene glycol, the viscosity of the electrolyte is high and the freezing point is relatively high, so the conductivity of the electrolyte decreases significantly at low temperatures. Bad characteristics.

Problems to be Solved by the Invention On the other hand, in order to improve low-temperature properties, ethylene glycol, r-butyrolactone, which has a wide freezing point to boiling point range, and N
It is conceivable to use an aprotic solvent such as , N-dimethylformamide and the above-mentioned anthonium salt of the branched aliphatic dicarboxylic acid, but this is not practical due to poor solubility of the solute.

Means for Solving the Problems The present inventor conducted intensive studies to find a method for dissolving a salt of a higher aliphatic dicarboxylic acid in an aprotic solvent, and discovered a method for dissolving a quaternary ammonium salt of the above acid. When you use
The present invention was completed by discovering that the solubility is significantly improved and high conductivity is exhibited.

That is, the present invention provides an electrolytic solution for an electrolytic capacitor, which is characterized in that a quaternary ammonium salt of a branched aliphatic cyclopic acid having a total carbon number of 11 to 30 is used as a solute.

Effects of the Invention The quaternary ammonium salt of a branched aliphatic dicarboxylic acid having a total carbon number of 11 to 30 and used as a solute in the present invention has good solubility in solvents and exhibits relatively high electrical conductivity. By using it together with a solvent having a wide freezing point to boiling point range, it becomes an excellent electrolytic solution for medium-high pressure electrolytic capacitors that can be used over a wide temperature range.

Detailed Description of the Invention In the quaternary ammonium salt of a branched aliphatic dicarboxylic acid having a total carbon number of 11 to 30 and used in the present invention, the aliphatic zocargon i1 has a total carbon number of 11 to 30. ~
30 and a branched chain, specifically, l, 5-
Octane dicarboxylic acid, l,6-zocandicar I phosphoric acid,
5,6-zocanedicalonic acid, 1,7-zocandicalonic acid, 4,6-dimethyl-4-nonene-1,2-dicalonic acid, 4,6-dimether-1,2-nonanodicalonic acid, l,7-dozocandicalonic acid Carunic acid, 5-ethyl-1,
10-Decanedical I phosphoric acid, 6-methyl-6-dodecene-1,12-dicalonic acid, 6-methyl-1,12-dodecanedical I phosphoric acid, 6-ethylene 1,12-dodecanedical I acid, 6- Nithyl-1,12-dicalonic acid, 7-methyl-7-thitradecene-1,14-dicalonic acid, 7-methyl-1,14-tetradecanedicalic acid, 3-hexyl-4-7''-dicalonic acid 1.2-dicarnic acid, 3-hexyl-1,2-decanedicarboxylic acid,
6-Nitylene-9-henyl-1,16-cyclonic acid, 6-nytylene-1,16-hexazokandicarganic acid, 6-phenyl-1,12-P:F 7.12-dimethyl-7,11-octadecadiene-1,18-dicalonic acid, 7.12-dimethyl-1#
Examples include 18-octadecanedicarboxylic acid, 6.8-, and the like.

Examples of quaternary ammonium salts include tetraethylamsonium, tetrapropylammonium, tetratutylammonium, methyltriethylammonium, methyltripropylammonium, methyltriethylammonium,
Aliphatic quaternary ammonium salts such as dimethyldiethylammonium, dimethylzoglobylammonium, dimethyldittylammonium, ethyltrinolobylammonium, nityltristylammonium, N,N-dimethylpyrrolidium, N,N-dimethylpiperidium Ni-1N
-Methyl-N-ethylpyrrolidinium, N-methyl-N
Examples include alicyclic quaternary ammonium salts such as -ethyl-peridinium and N,N-pentamethylene bihelidinium, and aromatic quaternary ammonium salts such as N-ethylpyridinium.

A quaternary ammonium salt of a branched aliphatic dicarboxylic acid having a total carbon number of 11 to 30 according to the present invention is dissolved, N-ethylformamide, N,N-dimethylformamide, N,N-
Dimethylformamide, N-methylacetamide, N-
Amide solvents such as ethylacetamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methylpyrrolidino7, r-tetra, r-
2 lactone solvents such as parelocton and δ-parec1 lactone, ethylene cargoes, propylene cargoes,
Examples include carnate solvents such as carnate, alcohol solvents such as ethylene glycol, glycerin, and methyl cellosolve, nitrile solvents such as 3-methoxysideropionitrile, and phosphoric acid ester solvents such as trimethyl phosphate, either alone or in combination. be able to.

Among these, a solvent mainly composed of r-tuterolactone is particularly preferable because it has low toxicity and is less likely to attack the sealing agent of an electrolytic capacitor or be mixed with pores.

The amount of the solute of the present invention dissolved in the above solvent is below the saturation concentration, preferably in the range of 1 to 40% by weight, and the lower the concentration, the higher the pressure resistance can be. Further, the molar ratio of acid and base in the dissolved salt of the electrolytic solution is usually in the range of 1:2 to 2:1.

The solute of the present invention can be prepared, for example, by neutralizing the dicarboxylic acid described above with an aqueous quaternary ammonium hydroxide solution in water or methanol, and then distilling off the solvent under reduced pressure.

Although obtained by vacuum drying, the electrolytic solution of the present invention can also be prepared by directly adding the dicarboxylic acid and quaternary ammonium hydroxide solution to a solvent, and then dehydrating the solution after a neutralization reaction.

The electrolytic solution of the present invention essentially has a total carbon number of 11 to 30.
The quaternary ammonium salt of a branched chain aliphatic dicarboxylic acid is used as a solvent, but co-solutes such as boric acid derivatives, for example, boric acid derivatives, etc. Phosphoric acid derivatives, nitrobenzene derivatives, etc. can be added.

EXPERIMENTAL EXAMPLE The 1811t of the present invention will be explained in more detail below with reference to Examples and Comparative Examples.

Example 1 5% by weight of 6-ethyl-1, in r-butyrolactone solvent
An electrolytic solution was obtained by decomposing monotetraethylammonium kflj of 16-hexarkandicalonic acid. The conductivity of this electrolyte at 25C is 2.0 m87-, +
The spark generation voltage was 355 V when a constant current of 4-i was applied to the smooth aluminum foil of the set.

Examples 2 to 6 In Example 1, the solute concentration was changed to 2 (Example 2) and 1, respectively.
0 (AI Example 3), 20 (Example 4), 30 (Example 5)
), 40 (Example 6) The electrical conductivity and spark generation voltage are shown in Table 1 when the weight is -.

Example 7 In place of r-butyrolactone solvent in Example 1,
The electrical conductivity and spark generation voltage when using N,N-dimethylformamide solvent are shown in Table 1.

Example 8 Electrical conductivity and spark generation voltage t-2g1 of an electrolytic solution dissolved in 20% by weight of monotetraethylammonium salt 1 of 3-henylsilyl-1,2-F'-power-endicalge7 acid in r-butyrolactone solvent It was shown to.

Example 9.10 In Example 8, instead of the monotetraethylammonium salt of 3-hexyl-1,2-decanedicarboxylic acid, 7,12-dimethyl-7,11-octadecadiene-
1,18-dicarboxylic acid (Example 9), 6,8-diphenyl-1,14-tetra-rcandicaronic acid (Example 1)
The conductivity and spark generation voltage t when using the monotetraethylammonium salt of 0) are shown in Table 1.

Comparative Example 1 Ethylene glycol solvent 11C 20% by weight ammonium salt of 6-ethyl-1,16-hexazocannocarginic acid t - Conductivity of dissolved electrolyte and spark generation voltage t
- Shown in Table 1.

Comparative Example 2 5 wt. of 6-ethyl-1, r-butyrolactone solvent
Although the ammonium salt of 16-hexazocandicalonic acid was added and heated, it did not partially dissolve, making it unsuitable for use as an electrolytic solution.

In Table 1, the following abbreviations were used.

GBL: 7-butyrolactone DMF': N,N-dimethylformamide EG: ethylene glycol Example 11 Changes in electrical conductivity of the electrolyte solutions of Example 4 and Comparative Example 1 with temperature were measured and are shown in FIG. The electrolytic solution of the present invention had significantly improved conductivity compared to the electrolytic solution of the comparative example, and did not solidify even at -50°C.

[Brief explanation of drawings]

FIG. 1 shows the electrolyte solution of the present invention in Example 11 (Example 4).
) is a diagram showing the temperature change (4) of the electrical conductivity and the temperature change (B) of the electrolytic solution of Comparative Example 1. Patent applicant: Mitsubishi Yuka Co., Ltd. Representative Patent Attorney Masahisa Hase I Takaya Yamamoto Figure 1 Temperature (0C)

Claims (1)

[Claims] An electrolytic solution for an electrolytic capacitor, characterized in that a quaternary ammonium salt of a branched aliphatic dicarboxylic acid having a total carbon number of 11 to 30 is used as a solute.