JPH02106915A - Electrolyte for driving electrolytic condenser and manufacture thereof - Google Patents

Abstract

PURPOSE:To enhance the performance by electrolyzing unsymmetrical quaternary ammonium halide having a specified composition in an electrolytic bath making a cation exchange film a diaphragm, and by using carboxylic acid unsymmetrical quaternary ammonium salt synthesized with the aqueous solution of the unsymmetrical quaternary ammonium hydroxide obtained by the electrolysis and used as raw material. CONSTITUTION:Unsymmetrical quaternary ammonium halide shown by the equation is electrolyzed in an electrolytic bath with a cation exchange film used as a diaphragm, and unsymmetrical quaternary ammonium hydroxide is obtained. With its aqueous solution used as raw material, carboxylic acid, unsymmetrical quaternary ammonium salt is synthesized and used. In the equation, R1 expresses alkyl with a carbon number 1 to 4; R2 and R3 express alkyl with carbon numbers 2 to 4; and X expresses a halogen. Chloride, bromide, iodide, etc., are given as examples of halide. As examples of unsymmetrical quaternary ammonium triethyl methyl ammonium, triisopropyl methyl ammonium, etc., are given, and they are obtained by reacting alkyl halide and tertiary amine corresponding to their constitution with water used as a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrolytic solution for driving an electrolytic capacitor and a method for manufacturing the same. More specifically, the present invention relates to an electrolytic solution for driving an electrolytic capacitor using a substantially halogen-free quaternary ammonium salt as an electrolyte, and a method for manufacturing the same.

[Prior Art] Conventionally, as an electrolytic solution for driving an electrolytic capacitor using a quaternary ammonium salt, a symmetrical quaternary ammonium halide such as tetramethylammonium chloride, tetraethylammonium chloride, or tetrabutylammonium chloride is used using a cation exchange membrane. An electrolytic solution (Japanese Unexamined Patent Publication No. 80518/1983) using a quaternary ammonium hydroxide aqueous solution obtained by electrolysis is known.

[Problems to be Solved by the Invention] However, in an electrolytic solution using a quaternary ammonium hydroxide aqueous solution obtained by conventional electrolysis of a symmetrical quaternary ammonium halide, the quaternary ammonium is tetraethylammonium, tetraisopropylammonium, or tetraethylammonium. When applied to a substance composed of an alkyl group larger than a methyl group such as butylammonium, the resistance of the cation exchange membrane is large and the membrane becomes blistered.
This caused problems such as an increase in sliding voltage and a decrease in current efficiency. Furthermore, the halogen removal rate of the quaternary ammonium hydroxide aqueous solution is not sufficient, and the electrolyte solution using it has problems such as high solute concentration, which causes corrosion of the capacitor and deterioration of the withstand voltage.

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

c. 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 that does not substantially contain halogen and a method for producing the same, and as a result, the present inventors have developed the present invention. The invention has been achieved.

That is, the electrolytic solution for driving an electrolytic capacitor of the present invention is
General formula (R+ represents an alkyl group having 1 to 4 carbon atoms, R1, R3
represents an alkyl group having 2 to 4 carbon atoms and X represents a halogen) is electrolyzed in an electrolytic cell with a cation exchange membrane as a diaphragm, and the resulting asymmetric quaternary ammonium hydro It is characterized by using a carboxylic acid asymmetric quaternary ammonium salt synthesized from an aqueous oxide solution as a raw material.

Examples of halides include chloride, bromide, iodite, etc., but chloride is preferred.

Examples of asymmetric quaternary ammoniums include triethylmethylammonium, triisopropylmethylammonium, methyltributylammonium, methylethyldiptylammonium, diethyldimethylammonium, dimethyldiisopropylammonium, dibutyldimethylammonium, tildimethylisopropylammonium, and the like. Among these, preferred are triethylmethylammonium, triisopropylmethylammonium, diethyldimethylammonium, dimethyldiisopropylammonium, and dibutyldimethylammonium. 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 is prepared by placing 33.5 parts by weight of triethylamine and 50 ffiffi parts of ion-exchanged water in a glass autoclave.
After carrying out a quaternization reaction by blowing 1 part of methyl chloride into the reaction mixture over several hours at 0°C and a pressure of 5 kg/cm"G, excess methyl chloride is removed by blowing in nitrogen or the like or by reducing the pressure. A 509A aqueous solution is obtained almost constantly.

Examples of carboxylic acids that form carboxylic acid asymmetric quaternary ammonium salts include unsaturated aliphatic carboxylic acids such as maleic acid, citraconic acid, and tetrahydrophthalic acid; aromatic carboxylic acids such as phthalic acid and benzoic acid; and hexahydrophthalic acid. Examples 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.

As the solvent for dissolving the asymmetric quaternary ammonium carboxylic acid salt to form an electrolytic solution, lactones such as γ-butyrolactone, carbonates such as propylene carbonate,
Amides such as DMF, nitriles such as acetonitrile,
Alcohols such as ethylene glycol and ethyl cellosolve, sulfolane, dimethyl sulfoxide, N-methylpyrrolidone, 3-methyl-1,3-oxazolidine-2-
1, 3-dimethyl-2-imidazolidinone and the like. Among these, preferred are γ-butyrolactone and a mixed solvent in which γ-butyrolactone is mixed with the above-mentioned solvents in a total amount of up to 50% by weight.

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

Example 1 Preparation of triethylmethylammonium maleate Nafion membrane 324 manufactured by DuPont as a cation exchange membrane
The electrolysis was separated into a cathode chamber with a stainless steel cathode and an anode chamber with a platinum-plated titanium anode. A 35% triethylmethylammonium chloride aqueous solution was circulated, and a 2% triethylmethylammonium hydroxide aqueous solution was added to the cathode chamber. The mixture was circulated for electrolysis at a current density of 10 to 2 OA/dm2 to obtain a crude 25% aqueous methyltritylammonium hydroxide solution in the cathode chamber. The chlorine concentration of this substance is
The current efficiency was 76%. Furthermore, using the same electrolytic device, the crude 25% triethylmethylammonium hydroxide aqueous solution obtained above was circulated in the anode chamber, and the 2% triethylmethylammonium hydroxide aqueous solution was circulated in the cathode chamber to maintain the same current density. Electrolysis was performed to obtain a highly purified 20% triethylmethylammonium hydroxide aqueous solution in the cathode chamber. The chlorine concentration of this product was 2 ppm. No abnormality occurred in the cation exchange membrane due to this electrolytic operation. This was collected, added with the same molar amount of maleic acid, and dried under reduced pressure to obtain triethylmethylammonium maleate. The solubility of this salt in γ-butyrolactone was 50% or more at 25"C.

Example 2 Preparation of triisopropylmethylammonium maleate A 125% aqueous solution of triisopropylmethylammonium hydroxide was obtained in the same manner as in Example 1 except that triisopropylmethylammonium chloride was used instead of triethylmethylammonium chloride. Ta. The chlorine concentration of this product was 2601)1)m, and the current efficiency was 72%. Subsequently, a highly purified 20% triisopropylmethylammonium hydroxide aqueous solution was obtained in the same manner. The chlorine concentration of this product is 3pp.
It was m. No abnormality occurred in the cation exchange membrane due to this electrolytic operation. Further, triisopropylmethylammonium maleate was obtained in the same manner.

The solubility of this salt in γ-butyrolactone is 25°C.
The concentration was 50% or more.

Example 3 Preparation of diethyldimethylammonium maleate A crude 25% diethyldimethylammonium hydroxide aqueous solution was obtained in the same manner as in Example 1, except that diethyldimethylammonium chloride was used in place of triethylmethylammonium chloride. The chlorine concentration of this product is 140 ppm, and the current efficiency is 84%.
Met. No abnormality occurred in the cation exchange membrane due to this electrolytic operation. Subsequently, a high purity 20% diethyldimethylammonium hydroxide aqueous solution was obtained in the same manner. The chlorine concentration of this product was 2 ppm. Furthermore, diethyldimethylammonium maleate was obtained in the same manner. The solubility of this salt in γ-butyrolactone is 2
It was over 500A at 5°C.

Example 4 Preparation of triethylmethylammonium phthalate Example 1
Triethylmethylammonium phthalate was obtained in the same manner except that phthalic acid was used instead of maleic acid. The solubility of this salt in γ-butyrolactone is 2
It was 50% or more at 5°C.

Example 5 Preparation of triisopropylmethylammonium phthalate The same procedure was repeated except that triisopropylmethylammonium chloride was used instead of triethylmethylammonium chloride in Example Ll+11, and phthalic acid was used instead of maleic acid. Triisopropylmethylammonium acid was obtained. The solubility of this salt in γ-butyrolactone was 50% or more at 25°C.

Example 6 Preparation of diethyldimethylammonium phthalate Example 1
Diethyldimethylammonium phthalate was obtained by carrying out the same procedure except that diethyldimethylammonium chloride was used instead of triethylmethylammonium chloride and phthalic acid was used instead of maleic acid. The solubility of this salt in γ-butyrolactone is 25°C.
It was more than 50%.

Conventional Example 1 Preparation of Tetramethylammonium Maleate A crude 25% aqueous solution of tetramethylammonium hydroxide was obtained in the same manner as in Example 1 except that tetramethylammonium chloride was used instead of triethylmethylammonium chloride. The chlorine content of this product is 12
The current efficiency was 87%. No abnormality occurred in the cation exchange membrane due to this electrolytic operation. Subsequently, the same procedure was carried out to obtain a tetramethylammonium hydroxide aqueous solution with a linearity of 20%. The chlorine concentration of this product was Oo-3 pp. Furthermore, tetramethylammonium maleate was obtained in the same manner. The solubility of this salt in γ-butyrolactone was less than 10% at 25°C.

Conventional Example 2 Preparation of Tetramethylammonium Phthalate The same procedure as in Example 1 was carried out except that tetramethylammonium chloride was used instead of triethylmethylammonium chloride and phthalic acid was used instead of maleic acid.
Tetramethylammonium phthalate was obtained. γ of this salt
- Solubility in butyrolactone was less than 30% at 25°C.

Conventional Example 3 Preparation of aqueous tetraethylammonium hydroxide 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. The chlorine concentration of this product was 450 ppm, and the current efficiency was 51%.

This electrolytic operation caused blisters on the cation exchange membrane, so subsequent operations could not be continued.

Conventional Example 4 Preparation of an aqueous solution of tetraisopropylammonium hydroxide A crude 25% aqueous solution of tetraisopropylammonium hydroxide was prepared in the same manner as in Example 1 except that tetraisopropylammonium chloride was used instead of triethylmethylammonium clot. Obtained. The chlorine concentration of this product is 510 ppm. T!
The flow efficiency was 41%. This electrolytic operation caused blisters on the cation exchange membrane, so subsequent operations could not be continued.

Example 7 The quaternary ammonium maleate salts obtained in Examples 1 to 3 and Conventional Example 1, in which highly purified quaternary ammonium salts could be obtained by electrolysis, were dissolved in γ-butyrolactone to obtain the maximum specific conductivity. The concentration was adjusted to obtain the desired value. The chlorine content of these electrolytes was all 5 ppm or less.

Table 1 shows the specific conductivity and concentration of the obtained electrolytic solution.

Table 1 [Effects of the Invention] The asymmetric quaternary ammonium nitride containing one or more but not more than two methyl groups of the present invention can be electrolyzed at low voltage and with high current efficiency without damaging the cation exchange membrane during electrolysis. It is easy to improve the halogen removal rate by further electrolyzing the obtained quaternary ammonium hydroxide aqueous solution or using a three-chamber tank as an electrolytic tank. In addition, the asymmetric quaternary ammonium nitride does not require a non-aqueous solvent such as alcohol during production and can be obtained as an aqueous solution, so there is no need for solvent replacement and it can be directly subjected to electrolysis. There is no generation of young colored matter or elution of electrode metal.

The carboxylic acid asymmetric quaternary ammonium salt synthesized using the asymmetric quaternary ammonium hydroxide aqueous solution obtained as a raw material contains virtually no halogen, nor does it contain silver or alkali metals, which causes problems such as corrosion of capacitors and short circuits. There is no. In addition, the solubility is increased compared to 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.

Therefore, according to the present invention, a substantially halogen-free and highly soluble carboxylic acid quaternary ammonium salt is produced,
This makes it possible to provide an electrolytic solution for driving an electrolytic capacitor that is non-corrosive, has high conductivity, and has excellent high-temperature stability and low-temperature stability.

Claims (3)

[Claims] 1. General formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (R_1 represents an alkyl group having 1 to 4 carbon atoms, R_2,
R_3 represents an alkyl group having 2 to 4 carbon atoms, X represents a halogen) is electrolyzed in an electrolytic cell with a cation exchange membrane as a diaphragm, and the resulting asymmetric quaternary ammonium An electrolytic solution for driving an electrolytic capacitor characterized by using an asymmetric quaternary ammonium carboxylic acid salt synthesized from an aqueous hydroxide solution 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, or dibutyldimethylammonium. 3. General formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (R_1 represents an alkyl group having 1 to 4 carbon atoms, R_2,
R_3 represents an alkyl group having 2 to 4 carbon atoms, X represents a halogen) is electrolyzed in an electrolytic cell with a cation exchange membrane as a diaphragm, and the resulting asymmetric quaternary ammonium A method for producing an electrolytic solution for driving an electrolytic capacitor, which comprises reacting an aqueous hydroxide solution with a carboxylic acid to produce an asymmetric quaternary ammonium salt of a carboxylic acid.