JP2998849B2 - Electrolyte for driving electrolytic capacitors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for driving an electrolytic capacitor.

[0002]

2. Description of the Related Art Heretofore, so-called ethylene glycol-boric acid-based electrolyte has been used as an electrolyte for driving an electrolytic capacitor particularly for medium and high pressures. This type of electrolyte is
When heated, water is generated by the esterification reaction of ethylene glycol and boric acid, and furthermore, the water reacts with the aluminum of the electrode to generate hydrogen gas. At a high temperature exceeding 100 ° C., the internal pressure increases. There was a disadvantage that it could not be used.

In order to improve such disadvantages, azelaic acid, sebacic acid, decanedicarboxylic acid or a salt thereof is partially used, but the solubility in a solvent such as ethylene glycol is poor, and the heat is poor. Insufficient stability.

Japanese Patent Application Laid-Open No. Sho 61-116815 proposes a method for improving solubility and thermal stability by using a tertiary monocarboxylic acid, but the chemical conversion is insufficient. Similarly, JP-A-1-103821 proposes a tertiary dicarboxylic acid, but has a drawback in that since it contains an ester group in the molecule, it reacts with ethylene glycol and deteriorates.

[0005]

SUMMARY OF THE INVENTION The present invention is to improve the thermal stability and solute solubility of a conventional electrolytic solution.

[0006]

Means for Solving the Problems The present inventors have proposed a solute to be used for an electrolytic solution. (1) By introducing a branched carbon chain structure (particularly an asymmetric structure), the solubility is improved and the conductivity is improved. Let it. (2) Chemical conversion is improved by introducing two carboxyl groups. (3) In order to sterically suppress esterification with ethylene glycol, a substituent is introduced at a position adjacent to the carboxyl group. (4) Except for two carboxyl groups, no functional group causing deterioration is introduced, and a skeleton is formed only with a methylene chain. As a result, the present inventors have found a salt of a tertiary dicarboxylic acid to satisfy the requirement.

The electrolytic solution for driving an electrolytic capacitor of the present invention comprises:
It is characterized by containing a salt of a tertiary dicarboxylic acid represented by the following general formula (I).

[0008]

Embedded image

(Wherein, n represents an integer of ¹ to 5, and R ¹ to
R ⁴ represents an alkyl group having 4 or less carbon atoms)

Hereinafter, the present invention will be described in detail. In the formula (I), examples of the alkyl group having 4 or less carbon atoms represented by R ^{1 to} R ⁴ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and an isobutyl group. ^{1 to} R ⁴ may be the same or different from each other.

Specific examples of the tertiary dicarboxylic acid represented by the formula (I) include, for example, 2,2,4,4-tetramethylglutaric acid, 2,2,5,5-tetramethyladipic acid, 2,2,6,6-tetramethylpimelic acid,
2,2,7,7-tetramethylsuberic acid, 2,2
8,8-tetramethylazelaic acid,

2,2,4,4-tetraethyl glutaric acid, 2,2,5,5-tetraethyl adipic acid, 2,2
2,6,6-tetraethylpimelic acid, 2,2,7,7
Tetraethyl suberic acid, 2,2,8,8-tetraethyl azelaic acid, 2,2,4,4-tetrapropyl glutaric acid, 2,2,5,5-tetrapropyl adipic acid,

2,2,6,6-tetrapropylpimelic acid, 2,2,7,7-tetrapropylsuberic acid,
2,8,8-tetrapropyl azelaic acid, 2,2
4,4-tetrabutyl glutaric acid, 2,2,5,5-tetrabutyl adipic acid, 2,2,6,6-tetrabutyl pimelic acid, 2,2,7,7-tetrabutyl suberic acid, 2 , 2,8,8-Tetrabutylazelaic acid, 2,
2, 4 - trimethyl-4 Echirugurutaru acid, 2,2,
5 -trimethyl-5-ethyladipic acid,

[0014] 2,2, 6 - trimethyl-6-Echirupimerin acid, 2,2, 7 - trimethyl-7 Echirusuberin acid, 2,2, 8 - trimethyl-8-ethyl azelaic acid, 2,2-dimethyl - 4,4-diethylglutaric acid,
2,2-dimethyl-5,5-diethyladipic acid, 2,
2-dimethyl-6,6-diethylpimelic acid,

2,2-dimethyl-7,7-diethylsuberic acid, 2,2-dimethyl-8,8-diethylazelaic acid, 2,4-dimethyl-2,4-diethylglutaric acid, 2,5-dimethyl -2,5-diethyladipic acid,
2,6-dimethyl-2,6-diethylpimelic acid, 2,
7-dimethyl-2,7-diethylsuberic acid,

2,8-dimethyl-2,8-diethylazelaic acid, 2-methyl-2,4,4-triethylglutaric acid, 2-methyl-2,5,5-triethyladipate, 2-methyl-2 , 6,6-triethylpimelic acid,
2-methyl-2,7,7-triethylsuberic acid, 2-
Methyl-2,8,8-triethylazelaic acid,

[0017] 2,2, 4 - trimethyl-4-propyl-glutaric acid, 2,2, 5 - trimethyl-5-propyl adipate, 2,2, 6 - trimethyl-6-Puropirupimerin acid, 2,2, 7 - trimethyl-7-propyl-slip phosphate, 2,2, 8 - trimethyl-8-propyl-azelaic acid, 2,2-dimethyl-4,4-dipropyl glutarate, 2,2-dimethyl-5,5-di Propyl adipic acid,

2,2-dimethyl-6,6-dipropylpimelic acid, 2,2-dimethyl-7,7-dipropylsuberic acid, 2,2-dimethyl-8,8-dipropylazelaic acid, 2,4-dimethyl-2,4-dipropylglutaric acid, 2,5-dimethyl-2,5-dipropyladipate, 2,6-dimethyl-2,6-dipropylpimelic acid, 2,7-dimethyl -2,7-dipropylsuberic acid,

2,8-dimethyl-2,8-dipropyl azelaic acid, 2-methyl-2,4,4-tripropyl glutaric acid, 2-methyl-2,5,5-tripropyl adipic acid, 2- methyl 2,6,6-tri-propylpiperidinium Mellin acid, 2-methyl -2,7,7- tripropyl slip phosphate, 2-methyl -2,8,8- tripropyl azelaic acid, 2,2, 4 - Trimethyl-4-butylglutaric acid,

[0020] 2,2, 5 - trimethyl-5-butyl adipate, 2,2, 6 - trimethyl-6-Buchirupimerin acid, 2,2, 7 - trimethyl-7 Buchirusuberin acid,
2,2, 8 - trimethyl-8-butyl azelate,

2,2-dimethyl-4,4-dibutylglutaric acid, 2,2-dimethyl-5,5-dibutyladipic acid, 2,2-dimethyl-6,6-dibutylpimelic acid,
2,2-dimethyl-7,7-dibutylsuberic acid, 2,
2-dimethyl-8,8-dibutylazelaic acid, 2,4
-Dimethyl-2,4-dibutylglutaric acid,

2,5-dimethyl-2,5-dibutyladipic acid, 2,6-dimethyl-2,6-dibutylpimelic acid, 2,7-dimethyl-2,7-dibutylsuberic acid,
2,8-dimethyl-2,8-dibutylazelaic acid, 2
-Methyl-2,4,4-tributyl glutaric acid, 2-methyl-2,5,5-tributyl adipic acid,

2-methyl-2,6,6-tributylpimelic acid, 2-methyl-2,7,7-tributylsuberic acid, 2-methyl-2,8,8-tributylazeleic acid, 2,2,2 4 - triethyl-4-propyl-glutaric acid, 2,2, 5 - triethyl-5-propyl adipate, 2,2, 6 - triethyl-6 Puropirupimerin acid,

[0024] 2,2, 7 - triethyl-7-propyl-slip phosphate, 2,2, 8 - triethyl-8-propyl-azelaic acid, 2,2-diethyl-4,4-dipropyl glutarate, 2,2 Diethyl-5,5-dipropyladipate, 2,2-diethyl-6,6-dipropylpimelic acid, 2,2-diethyl-7,7-dipropylsuberic acid, 2,2-diethyl-8, 8-dipropyl azelaic acid,

2,4-diethyl-2,4-dipropylglutaric acid, 2,5-diethyl-2,5-dipropyladipate, 2,6-diethyl-2,6-dipropylpimelic acid, , 7-Diethyl-2,7-dipropylsuberic acid, 2,8-diethyl-2,8-dipropylazelaic acid, 2-ethyl-2,4,4-tripropylglutaric acid, 2-ethyl-2, 5,5-tripropyladipic acid,

2-ethyl-2,6,6-tripropylpimelic acid, 2-ethyl-2,7,7-tripropylsuberic acid, 2-ethyl-2,8,8-tripropylazelaic acid, , 2, 4 - triethyl-4 Buchirugurutaru acid, 2,2, 5 - triethyl-5-butyl adipate,
2,2, 6 - triethyl-6 Buchirupimerin acid,

[0027] 2,2, 7 - triethyl-7 Buchirusuberin acid, 2,2, 8 - triethyl-8-butyl azelaic acid, 2,2-diethyl-4,4-Jibuchirugurutaru acid, 2,2-diethyl -5,5-dibutyladipic acid,
2,2-diethyl-6,6-dibutylpimelic acid, 2,
2-diethyl-7,7-dibutylsuberic acid, 2,2-
Diethyl-8,8-dibutylazelaic acid, 2,4-diethyl-2,4-dibutylglutaric acid, 2,5-diethyl-2,5-dibutyladipic acid,

2,6-diethyl-2,6-dibutylpimelic acid, 2,7-diethyl-2,7-dibutylsuberic acid, 2,8-diethyl-2,8-dibutylazelaic acid, 2-ethyl-2, 4,4-tributyl glutaric acid,
2-ethyl-2,5,5-tributyladipate, 2-
Ethyl-2,6,6-tributylpimelic acid, 2-ethyl-2,7,7-tributylsuberic acid, 2-ethyl-
2,8,8- tributyl azelaic acid, 2,2, 4 - tri-propyl-4 Buchirugurutaru acid,

[0029] 2,2, 5 - tri-5- butyl adipic acid, 2,2, 6 - tri-6- Buchirupimerin acid, 2,2, 7 - tri-7- Buchirusuberin acid, 2,2 , 8 -Tripropyl-8-butylazelaic acid, 2,2-dipropyl-4,4-dibutylglutaric acid, 2,2-dipropyl-5,5-dibutyladipate, 2,2-dipropyl-6,6- Dibutylpimelic acid,

2,2-dipropyl-7,7-dibutylsuberic acid, 2,2-dipropyl-8,8-dibutylazelaic acid, 2,4-dipropyl-2,4-dibutylglutaric acid, 2,5-dipropyl -2,5-dibutyladipic acid, 2,6-dipropyl-2,6-dibutylpimelic acid, 2,7-dipropyl-2,7-dibutylsuberic acid, 2,8-dipropyl-2,8-dibutylazelaic acid,

2-propyl-2,4,4-tributylglutaric acid, 2-propyl-2,5,5-tributyladipate, 2-propyl-2,6,6-tributylpimelic acid, 2-propyl- 2,7,7-tributylsuberic acid, 2-propyl-2,8,8-tributylazelaic acid, 2,2-dimethyl-4-ethyl-4-propylglutaric acid,

2,5-dimethyl-2-ethyl-5-propyladipate, 2-methyl-2-ethyl-4-propyl-4-butylglutarate, 2-methyl-2-butyl-
5-ethyl-5-propyladipate, 2-methyl-2
-Propyl-6-ethyl-6-butylpimelic acid.

These carboxylic acids can be used alone or as a mixture. Those having different alkyl groups of R ^{1 to} R ⁴ are a mixture of optical isomers. Generally, the more asymmetric one is, the better the solubility in a solvent is. In addition, the solubility generally tends to deteriorate as the carbon number increases.

The tertiary dicarboxylic acid salt used in the present invention includes, for example, the ammonium, amine, quaternary ammonium, phosphonium and sulfonium salts of the above carboxylic acids.

As the solvent for dissolving the salt of the tertiary dicarboxylic acid used in the present invention, for example, N-methylformamide, N-ethylformamide, N, N-dimethylformamide, N, N-diethylformamide, N-ethyl Amide solvents such as acetamide, N, N-dimethylacetamide, N-methylpyrrolidinone; lactone solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone;

Carbonate solvents such as ethylene carbonate, propylene carbonate, butylene carbonate and the like;
Alcohol solvents such as ethylene glycol, glycerin and methyl cellosolve; nitrile solvents such as 3-methoxypropionitrile and glutarnitrile; phosphate ester solvents such as trimethyl phosphate and triethyl phosphate; Examples thereof include a mixture of two or more solvents.

The amount of the solute dissolved in the solvent varies depending on the conductivity of the electrolytic solution to be obtained, but is generally less than the saturation concentration, preferably 1 to 25% by weight. In the electrolyte of the present invention, in addition to the above-mentioned tertiary dicarboxylic acid salt and solvent, various auxiliary solutes for the purpose of preventing electrolytic corrosion, reducing leakage current, absorbing hydrogen gas, etc., for example, phosphoric acid derivatives, nitrobenzene derivatives Etc. can be added.

Further, if necessary within a range not to impair the object of the present invention, 1 to 1
0% by weight of water can be added.

[0039]

The tertiary dicarboxylic acid salt used as a solute in the present invention has good solubility in a solvent, and its electrolytic solution can maintain a relatively high conductivity and a spark voltage, Since the stability is high, a long-life medium-to-high pressure electrolytic capacitor can be obtained.

[0040]

EXAMPLES (Example 1) Diammonium 2,2,6,6-tetramethylpimelate was dissolved at 10% by weight in an ethylene glycol solvent to prepare an electrolytic solution. The conductivity of this electrolytic solution was 1.8 mS / cm at 25 ° C., and the spark voltage when a current of 5 mA / cm ² was applied to the aluminum electrode was 430 V
Met.

Example 2 A solute was changed to diammonium 2,2,8,8-tetramethylazelate,
An electrolytic solution was prepared in the same manner as in Example 1, and the electric conductivity and the spark voltage were measured. The conductivity was 1.7 mS / cm and the spark voltage was 440V.

Example 3 The solute was converted to 2,6-diethyl-
An electrolyte was prepared in the same manner as in Example 1 except that diammonium 2,6-dibutylpimelate was used, and the electric conductivity and the spark voltage were measured. The conductivity is 1.3 mS / cm,
The spark voltage was 485V.

Example 4 The solute was 2,6-dimethyl-
An electrolytic solution was prepared in the same manner as in Example 1 except that diammonium 2,6-diethylpimelate was used, and the electric conductivity and the spark voltage were measured. The conductivity is 1.2 mS / cm 2,
The spark voltage was 470V. Next, the electrolytic solution was sealed and allowed to stand at 110 ° C. for 1000 hours, and then the conductivity of the electrolytic solution was measured. The electric conductivity was 1.2 mS / cm 2, and no deterioration was observed.

Example 5 The solute was converted to 2,7-dimethyl-
An electrolytic solution was prepared in the same manner as in Example 1 except that diammonium 2,7-diethylsuberate was used, and the electric conductivity and the spark voltage were measured. The conductivity is 1.2 mS / cm 2,
The spark voltage was 490V. Next, the electrolytic solution was sealed and allowed to stand at 110 ° C. for 1000 hours, and then the conductivity of the electrolytic solution was measured. The electric conductivity was 1.2 mS / cm 2, and no deterioration was observed.

Comparative Example 1 An electrolyte was prepared in the same manner as in Example 1 except that the solute was changed to ammonium borate.
The conductivity and the spark voltage were measured. Conductivity is 1.1mS / cm
And the spark voltage was 490V. Next, the electrolytic solution was sealed and allowed to stand at 110 ° C. for 1000 hours, and then the conductivity of the electrolytic solution was measured. The conductivity is 0.8mS / cm,
Deterioration of the electrolyte was observed.

(Comparative Example 2)
The following formula described in the official gazette:

[0047]

Embedded image

An electrolytic solution was prepared in the same manner as in Example 1 except that the diammonium salt of a tertiary dicarboxylic acid shown in the above was used, and the electric conductivity and the spark voltage were measured. The conductivity was 1.0 mS / cm and the spark voltage was 495V.

Next, the electrolytic solution was sealed and sealed at 110 ° C. for 1 hour.
After standing for 000 hours, the mixture was cooled to room temperature and solidified due to deterioration. NMR analysis of the deteriorated product revealed that the ester bond in the solute molecule was completely broken.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-277207 (JP, A) JP-A-1-295411 (JP, A) JP-A-1-287915 (JP, A) JP-A-1- 282811 (JP, A) JP-A-1-196808 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01G 9/035

Claims (1)

(57) [Claims] 1. An electrolytic solution for driving an electrolytic capacitor, comprising a salt of a tertiary dicarboxylic acid represented by the following general formula (I). Embedded image (In the formula, n represents an integer of 1 to 5, and R ^{1 to} R ⁴ each represent an alkyl group having 4 or less carbon atoms.)