JP2739217B2 - Electrolytic solution for driving electrolytic capacitor and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrolytic solution for driving an electrolytic capacitor and a method for producing the same. More specifically, the present invention relates to an electrolytic solution for driving an electrolytic capacitor using a quaternary ammonium salt containing substantially no halogen as an electrolyte, and a method for producing the same.

[Prior art] Conventionally, symmetric quaternary ammonium halides such as tetramethylammonium chloride, tetraethylammonium chloride and tetrabutylammonium chloride have been used as cation exchange membranes as electrolytes for driving electrolytic capacitors using quaternary ammonium salts. An electrolytic solution using a quaternary ammonium hydroxide aqueous solution obtained by electrolysis (JP-A-63-80516) is known.

[Problems to be Solved by the Invention] However, in the conventional electrolytic solution using a quaternary ammonium hydroxide aqueous solution obtained by electrolysis of a symmetric quaternary ammonium halide, the quaternary ammonium is tetraethylammonium, tetraisopropylammonium, When applied to an alkyl group larger than a methyl group such as butylammonium, the resistance of the cation exchange membrane is large, blisters (water swelling phenomenon) easily occur in the membrane, increase in cell voltage, current efficiency Problems, such as a decrease in In addition, the quaternary ammonium hydroxide aqueous solution does not have a sufficient halogen removal rate, and an electrolytic solution using the same has a problem that it causes corrosion of a capacitor and deterioration of withstand voltage at a high solute concentration.

Therefore, an object of the present invention is to provide a high-performance electrolytic capacitor using a quaternary ammonium salt having a high solubility in an electrolytic solution used for the electrolytic capacitor and a method substantially free of halogen. It is in.

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies to find a highly soluble quaternary ammonium salt substantially free of halogen and a method for producing the same, The invention has been reached.

That is, the electrolytic solution for driving the electrolytic capacitor of the present invention is:
General formula (1) (R ₁ represents an alkyl group having 1 to 4 carbon atoms, and R ₂ and R ₃
Represents an alkyl group having 2 to 4 carbon atoms, and X represents a halogen), and electrolyze the resulting asymmetric quaternary ammonium halide in an electrolytic cell having a cation exchange membrane as a diaphragm. It is characterized by using a carboxylic acid asymmetric quaternary ammonium salt synthesized from an aqueous solution of xide as a raw material.

Examples of the halide include chloride, bromide, iodide and the like, and chloride is preferred.

Examples of asymmetric quaternary ammoniums include triethylmethylammonium, triisopropylmethylammonium, methyltributylammonium, methylethyldibutylammonium, diethyldimethylammonium, dimethyldiisopropylammonium, dibutyldimethylammonium, ethyldimethylisopropylammonium and the like. Of these, triethylmethylammonium, triisopropylmethylammonium, diethyldimethylammonium, dimethyldiisopropylammonium and dibutyldimethylammonium are preferred. More preferred are triethylmethylammonium and diethyldimethylammonium.

These asymmetric quaternary ammonium halides can be obtained by reacting a tertiary amine corresponding to the structure with an alkyl halide using water as a solvent. For example, triethylmethylammonium chloride, 33.5 parts by weight of triethylamine in a glass autoclave,
Charge 50 parts by weight of ion-exchanged water, temperature about 60 ° C, pressure 5kg / cm
^A quaternization reaction is carried out by blowing 17.5 parts by weight of methyl chloride in a few hours under the condition of 2G, and then a method of removing excess methyl chloride by blowing nitrogen or the like or slightly reducing the pressure.
A 50% aqueous solution is obtained almost quantitatively.

Examples of the carboxylic acids that form the carboxylic acid asymmetric quaternary ammonium salts include unsaturated aliphatic carboxylic acids such as maleic acid, citraconic acid and tetrahydrophthalic acid, phthalic acid, aromatic carboxylic acids such as benzoic acid, and hexahydrophthalic acid. Examples thereof include alicyclic aliphatic carboxylic acids such as acids, aliphatic monocarboxylic acids such as acetic acid and propionic acid, and saturated aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid, azelaic acid and decanedicarboxylic acid.

Solvents for dissolving the carboxylic acid asymmetric quaternary ammonium salt to form an electrolytic solution include lactones such as γ-butyrolactone, carbonates such as propylene carbonate, amides such as DMF, nitriles such as acetonitrile, ethylene glycol, and ethyl. Alcohols such as cellosolve, sulfolane, dimethyl sulfoxide, N-methylpyrrolidone, 3-methyl-1,3-oxazolidine-2
-One, 1,3-dimethyl-2-imidazolidinone and the like. Of these, γ-butyrolactone and a mixed solvent obtained by mixing γ-butyrolactone with the above-mentioned solvents in an amount of 50% by weight or less are preferable.

[Examples] Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto. In the following,% indicates% by weight.

Example 1 Preparation of triethylmethylammonium maleate Nafion membrane 324 manufactured by DuPont as a cation exchange membrane
The electrolytic cell is separated into a stainless steel cathode chamber and a platinum-plated titanium anode chamber by circulating a 35% aqueous solution of triethylmethylammonium chloride and a 2% aqueous solution of triethylmethylammonium hydroxide in the cathode chamber. The solution was circulated and electrolyzed at a current density of 10 to 20 A / dm ² to obtain a crude 25% aqueous solution of methyltritylammonium hydroxide in the cathode chamber. Its chlorine concentration was 190 ppm, and its current efficiency was 76%. Further, using the same electrolytic apparatus, the crude 25% aqueous solution of triethylmethylammonium hydroxide obtained above was circulated in the anode chamber, and the 2% aqueous solution of triethylmethylammonium hydroxide was circulated in the cathode chamber, and the same current density was obtained. And a 20% aqueous solution of high-purity triethylmethylammonium hydroxide was obtained in the cathode chamber. This had a chlorine concentration of 2 ppm. No abnormality of the cation exchange membrane was caused by this electrolysis operation. This was collected, added with an equimolar amount of maleic acid, and dried under reduced pressure to obtain triethylmethylammonium maleate. The solubility of this salt in γ-butyrolactone is 25 ° C.
And the concentration was 50% or more.

Example 2 Preparation of triisopropylmethylammonium maleate The procedure of Example 1 was repeated, except that triisopropylmethylammonium chloride was used instead of triethylmethylammonium chloride, to obtain a crude 25% aqueous solution of triisopropylmethylammonium hydroxide. Was. It has a chlorine concentration of 260 ppm and a current efficiency of 72 ppm.
%Met. Subsequently, the same procedure was performed to obtain a high-purity 20% aqueous solution of triisopropylmethylammonium hydroxide. This had a chlorine concentration of 3 ppm. No abnormality of the cation exchange membrane was caused by this electrolysis operation. The same operation was performed to obtain triisopropylmethylammonium maleate. The solubility of this salt in γ-butyrolactone was 50% or more at 25 ° C.

Example 3 Preparation of diethyldimethylammonium maleate A crude 25% aqueous solution of diethyldimethylammonium hydroxide was obtained in the same manner as in Example 1, except that diethyldimethylammonium chloride was used instead of triethylmethylammonium chloride. The chlorine concentration was 140 ppm and the current efficiency was 84%. No abnormality of the cation exchange membrane was caused by this electrolysis operation. Subsequently, the same operation was performed to obtain a high-purity 20% aqueous solution of diethyldimethylammonium hydroxide. This had a chlorine concentration of 2 ppm. Further, the same procedure was performed to obtain diethyldimethylammonium maleate. The solubility of this salt in γ-butyrolactone was at least 50% at 25 ° C.

Example 4 Preparation of triethylmethylammonium phthalate Triethylmethylammonium phthalate was obtained in the same manner as in Example 1, except that phthalic acid was used instead of maleic acid. The solubility of this salt in γ-butyrolactone was at least 50% at 25 ° C.

Example 5 Preparation of triisopropylmethylammonium phthalate The procedure of Example 1 was repeated, except that triisopropylmethylammonium chloride was used instead of triethylmethylammonium chloride and phthalic acid was used instead of maleic acid. Triisopropylmethylammonium acid was obtained. The solubility of this salt in γ-butyrolactone was at least 50% at 25 ° C.

Example 6 Preparation of diethyldimethylammonium phthalate The procedure of Example 1 was repeated except that diethyldimethylammonium chloride was used instead of triethylmethylammonium chloride and phthalic acid was used instead of maleic acid. Dimethyl ammonium was obtained. The solubility of this salt in γ-butyrolactone was at least 50% at 25 ° C.

Conventional Example 1 Preparation of tetramethylammonium maleate Except that tetramethylammonium chloride was used instead of triethylmethylammonium chloride in Example 1, a crude aqueous solution of tetramethylammonium hydroxide was obtained at 25 ° C. This had a chlorine content of 120 ppm and a current efficiency of 87%. No abnormality of the cation exchange membrane was caused by this electrolysis operation. Subsequently, the same operation was performed to obtain a high-purity 20% aqueous solution of tetramethylammonium hydroxide. The chlorine concentration of this is
0.3 ppm. Further, tetramethylammonium maleate was obtained in the same manner. The solubility of this salt in γ-butyrolactone at 25 ° C. was 10% or less.

Conventional Example 2 Preparation of tetramethylammonium phthalate Example 1 was repeated except that tetramethylammonium chloride was used instead of triethylmethylammonium chloride and phthalic acid was used instead of maleic acid. Methyl ammonium was obtained. The solubility of this salt in γ-butyrolactone is 25 ° C.
Was less than 30%.

Conventional Example 3 Preparation of Tetraethylammonium Hydroxide Aqueous Solution A crude 25% aqueous solution of tetraethylammonium hydroxide was obtained in the same manner as in Example 1 except that tetraethylammonium chloride was used instead of triethylmethylammonium chloride. This had a chlorine concentration of 450 ppm and a current efficiency of 51%. This electrolysis operation caused blisters (water blisters) on the cation exchange membrane, and the subsequent operations could not be continued.

Conventional example 4 Preparation of aqueous solution of tetraisopropylammonium hydroxide A similar procedure was carried out except that tetraisopropylammonium chloride was used instead of triethylmethylammonium chloride in Example 1, to obtain a crude 25% aqueous solution of tetraisopropylammonium hydroxide. . The chlorine concentration was 510 ppm and the current efficiency was 41%. This electrolysis operation caused blisters (water blisters) on the cation exchange membrane, and the subsequent operations could not be continued.

Example 7 The quaternary ammonium maleate obtained in Examples 1 to 3 and Conventional Example 1 in which a high-purity quaternary ammonium salt could be obtained by electrolysis was dissolved in γ-butyrolactone, and the specific conductivity was maximized. The concentration was adjusted to obtain a value. All of these electrolytes had a chlorine content of 5 ppm or less. Table 1 shows the specific conductivity and the concentration of the obtained electrolytic solution.

[Effect of the Invention] The asymmetric quaternary ammonium halide of the present invention containing one or more and no more than two methyl groups enables electrolysis at low voltage and high current efficiency without damaging the cation exchange membrane during electrolysis. It is easy to improve the halogen removal rate by a method of further electrolyzing the obtained quaternary ammonium hydroxide aqueous solution or a method of using a three-chamber tank as the electrolytic cell. In addition, the asymmetric quaternary ammonium halide can be obtained as an aqueous solution without the need for a non-aqueous solvent such as alcohol at the time of production, so there is no need for solvent replacement, and it can be used for electrolysis as it is, and a colored substance obtained by mixing an organic solvent. And no elution of electrode metal. The carboxylic acid asymmetric quaternary ammonium salt synthesized from the aqueous solution of asymmetric quaternary ammonium hydroxide thus obtained contains substantially no halogen and no silver or alkali metal. There is no. Further, the solubility is higher than that of an asymmetric quaternary ammonium salt of an inorganic anion or a symmetric quaternary ammonium salt of a carboxylic acid, and high conductivity can be obtained by increasing the concentration.

Thus, according to the present invention, a quaternary ammonium carboxylate which is substantially free of halogen and which has high solubility is produced, whereby it has no corrosiveness, high conductivity, high temperature stability and low temperature stability. It is possible to provide an electrolytic solution for driving an electrolytic capacitor having excellent characteristics.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hideki Shimamoto 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Hisao Nagara 1006 Kadoma Kadoma Kadoma, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Yugari Washio 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshiteru Kuwae 11-11 Hitotsubashi Nohonmachi, Higashiyama-ku, Kyoto City, Kyoto Prefecture Sanyo Chemical Industry Co., Ltd. 72) Inventor Kazushi Shiono 1 Sanyo Chemical Industry Co., Ltd., 11-11, Hitotsubashi-Honcho, Higashiyama-ku, Kyoto-shi, Kyoto (72) Inventor Takaaki No. 1 Sanyo Chemical Industry Co., Ltd. 11, 11- Hitotsubashi-Honcho, Higashiyama-ku, Kyoto, Kyoto, Japan Inside

Claims (3)

(57) [Claims] 1. The general formula (1) Wherein R ₁ represents an alkyl group having 1 to 4 carbon atoms, R ₂ and R ₃ each represent an alkyl group having 2 to 4 carbon atoms, and X represents a halogen. An electrolytic solution for driving an electrolytic capacitor, characterized by using an asymmetric quaternary ammonium salt of carboxylic acid synthesized by electrolysis in an electrolytic cell having an exchange membrane as a diaphragm and using the obtained aqueous solution of asymmetric quaternary ammonium hydroxide as a raw material. 2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the asymmetric quaternary ammonium is triethylmethylammonium, triisopropylmethylammonium, diethyldimethylammonium, dimethyldiisopropylammonium, dibutyldimethylammonium. 3. The formula (1) Wherein R ₁ represents an alkyl group having 1 to 4 carbon atoms, R ₂ and R ₃ each represent an alkyl group having 2 to 4 carbon atoms, and X represents a halogen. Electrolysis in an electrolytic cell using an exchange membrane as a diaphragm, and reacting the obtained asymmetric quaternary ammonium hydroxide aqueous solution with carboxylic acid to produce a carboxylic acid asymmetric quaternary ammonium salt. Liquid production method.