JP2016100511A - Electrolytic capacitor driving electrolyte and electrolytic capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolytic solution for driving an electrolytic capacitor, which has excellent thermal stability, and high solubility in solvent, and which can be arranged to have high voltage resistance.SOLUTION: An electrolytic solution for driving an electrolytic capacitor comprises a compound having a particular chemical formula, and an electrolyte selected from a group consisting of salts of the compound which are dissolved in a solvent. It is preferable that the content of the electrolyte is 4.7-16.8 wt.%.SELECTED DRAWING: None

Description

  The present invention relates to an electrolytic solution for driving an electrolytic capacitor having excellent thermal stability and high withstand voltage (hereinafter referred to as an electrolytic solution). The present invention also relates to an electrolytic capacitor using such an electrolytic solution.

An electrolytic capacitor is one of common electronic components, and is widely used in various electronic components and electrical products, mainly for power supply circuits and digital circuit noise filters.
Conventionally, in a high-voltage electrolytic capacitor, in order to maintain a withstand voltage characteristic, a higher dibasic acid having a high molecular weight or a salt thereof having a main skeleton as a linear alkyl group is added to a solvent mainly composed of ethylene glycol or the like. Dissolved electrolytes (see, for example, Patent Document 1 and Patent Document 2) are used, but higher dibasic acids have lower molecular weight as the molecular weight increases, so that the molecular weight that can be used, and The amount added is limited.

  Further, the conventional higher dibasic acid is esterified with ethylene glycol or the like as a solvent in a high temperature atmosphere and characteristic deterioration such as an increase in specific resistance of the electrolytic solution occurs.

  In order to solve such problems in the prior art, for example, Patent Document 3 and Patent Document 4 listed below describe dicarboxylic acids having a branched chain at the α-position for the purpose of improving solubility in a solvent. Or the electrolyte solution containing the salt is proposed.

JP 2000-315629 A JP 2006-108158 A JP 2009-272627 A JP 2010-232630 A

However, in the case of the electrolytic solutions described in Patent Documents 3 and 4, there is a limit in the molecular weight that can be dissolved, and there is a problem that the solubility is insufficient as an application of the high-pressure electrolytic solution.
The present invention solves the above-mentioned problems, and even when the molecular weight is increased, by using a higher dibasic acid having higher solubility in a solvent, a higher withstand voltage can be achieved, and thermal stability (high temperature standing) It is an object of the present invention to provide an electrolytic solution for driving an electrolytic capacitor having a low specific resistance change rate) and an electrolytic capacitor using the electrolytic solution.

In order to solve the above-mentioned problems, the present inventors have conducted intensive studies, and as a result, introduced a plurality of polar “plural ether groups (—O—)” into the structure, and a substituent (R ₁ ) at the α-position. , R ₂ ) introduced higher dibasic acid as an electrolyte, so that the solubility in a solvent can be increased even if the molecular weight is increased, the withstand voltage can be increased, and the thermal stability is excellent. As a result, the present invention has been completed.

  That is, the present invention is an electrolytic solution for driving an electrolytic capacitor obtained by dissolving an electrolyte in a solvent, wherein the electrolyte is selected from the group consisting of a compound having the following general formula and a salt of the compound: It is characterized by being.

  In the electrolyte solution of the present invention thus configured, the electrolyte is selected from the group consisting of a compound having the above general formula and a salt of the compound, thereby increasing the molecular weight. However, since the solubility in a solvent can be increased, a high withstand voltage can be achieved and the thermal stability can be improved.

  Further, the present invention is characterized in that, in the electrolytic solution having the above characteristics, X in the chemical formula 1 is the following general formula.

Further, the present invention is characterized in that, in the electrolytic solution having the above characteristics, R ₁ in the chemical formula ₁ represents C ₄ H ₉ , C ₅ H ₁₁ or C ₆ H ₁₃ , and R ₂ represents hydrogen. Is.

  Further, the present invention provides an electrolyte solution having the above characteristics, wherein m in Formula 2 is 2 or 4, n is 2 to 23, and the electrolyte is dissolved in a solvent by 4.7 to 16.8% by weight. It is characterized by that.

  Further, the present invention provides an electrolyte solution having the above characteristics, wherein the solvent is glycols, lactones, nitriles, alcohols, ethers, ketones, esters, carbonates, sulfolanes, amides, oxazolidinones , One or more selected from the group consisting of sulfones and water.

  The present invention is also characterized in that, in the electrolytic solution having the above characteristics, the solvent is a mixed solvent of ethylene glycol and water.

  Further, the present invention provides the electrolyte having the above characteristics, wherein the salt is selected from the group consisting of a primary amine salt, a secondary amine salt, a tertiary amine salt, a quaternary ammonium salt, and an imidazolinium salt. It is characterized by being.

  Furthermore, the electrolytic capacitor of the present invention is characterized by having a capacitor element impregnated with the above electrolytic solution.

  According to the present invention, by using the compound of the above chemical formula 1 and the salt of the compound as an electrolyte, the solubility in a solvent can be increased even when the molecular weight is increased. It is possible to provide an electrolytic solution for driving an electrolytic capacitor capable of improving the thermal stability and an electrolytic capacitor using the electrolytic solution, thereby prolonging the life of the medium- and high-voltage electrolyte and increasing the electrolytic solution. Reliability can be achieved.

The electrolyte solution according to the present invention only needs to include an electrolyte selected from the group consisting of the compound having the above general formula and a salt of the compound, and includes only one type of the electrolyte or two or more types. You may go out.
Since the compound having the above general formula and the salt of the compound have one or more ether bonds (1 to 23) in X, even if the molecular weight is increased, the compound has a solubility in a solvent such as ethylene glycol. It is possible to increase. In addition, since this compound has a substituent (R ₁ , R ₂ ) introduced at the α-position, it suppresses esterification with a solvent (ethylene glycol or the like) and amidation with ammonia, ammonium salt, or amine salt. By doing so, the thermal stability can be improved.

The substituents R ₁ and R ₂ in the above general formula are preferably hydrogen, a butyl group or a hexyl group, and at least one of R ₁ and R ₂ is preferably a butyl group or a hexyl group. At this time, a butyl group is more preferable from the viewpoint that the thermal stability can be increased and the initial specific resistance characteristic can be reduced with respect to the suppression of the esterification reaction with ethylene glycol or the like. X in the above general formula represents an alkylene ether or a polyether polyol, and those represented by the general formula of the above chemical formula 2 are preferred.
Moreover, n in the general formula of the above chemical formula 2 represents an integer of 1 to 23, and by increasing the number of carbons in the main chain, it is possible to increase the withstand voltage (improve the withstand voltage). Note that m in the above formula 2 is preferably an integer of 2 or 4 from the viewpoint of reducing the specific resistance and the change thereof.

  Preferred salts of the compound having the above general formula include diammonium salts, primary amine salts such as methylamine, ethylamine and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine and diethylamine, trimethylamine, Examples include tertiary amine salts such as diethylmethylamine, ethyldimethylamine, and triethylamine, quaternary ammonium salts such as tetramethylammonium, triethylmethylammonium, and tetraethylammonium, imidazolinium salts, and imidazolium salts. A preferred salt in the present invention is an ammonium salt.

The electrolytic solution according to the present invention has a high withstand voltage with respect to weight concentration. When m in Formula 2 is 2 or 4 and n is 2 to 23, the electrolyte is adjusted to 4.7 to 16.8% by weight, thereby suppressing an increase in specific resistance and high resistance. Voltage can be realized.
Conventional electrolytes have a problem that it is difficult to increase the withstand voltage due to low solubility in a solvent, and that the withstand voltage tends to decrease when the electrolyte concentration is increased. Even when the molecular weight is increased, the electrolyte can increase the solubility in a solvent.

  Examples of the solvent used in the present invention include glycols, lactones, nitriles, alcohols, ethers, ketones, esters, carbonates, sulfones, sulfolanes, and water. 2 or more can be mixed and used. Specific examples of the solvent are as follows.

Examples of glycols include ethylene glycol, propylene glycol, diethylene glycol, hexylene glycol, and the like, and ethylene glycol, which is a solvent for obtaining an electrolyte solution having excellent temperature characteristics, is preferable. Although ethylene glycol can be used alone, it is more preferable to use a mixed solution with water in order to reduce the specific resistance.
When the solvent is ethylene glycol, the ethylene glycol concentration in the electrolytic solution is preferably 77.5 to 93.5% by weight, more preferably 81.0 to 92.5% by weight. When water is used in combination, the concentration of water in the electrolytic solution is preferably 0.5 to 10.0% by weight, more preferably 1.0 to 3.0% by weight.

  Examples of lactones include γ-butyrolactone, α-acetyl-γ-butyrolactone, β-butyrolactone, γ-valerolactone, and δ-valerolactone.

  Examples of nitriles include acetonitrile, acrylonitrile, adiponitrile, 3-methoxypropionitrile and the like.

  Examples of alcohols include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, diacetone alcohol, benzyl alcohol, amyl alcohol, furfuryl alcohol, glycerin, hexitol and the like.

  The ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol phenyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol. Examples include diethyl ether.

  Examples of ketones include acetone and methyl ethyl ketone.

  Esters include methyl acetate, ethyl acetate, butyl acetate and the like.

  Examples of carbonates include ethylene carbonate and propylene carbonate.

  As amides, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N, N-diethyl Examples include acetamide and hexamethylphosphoric amide.

  Examples of oxazolidinones include N-methyl-2-oxazolidinone and 3,5-dimethyl-2-oxazolidinone.

  Examples of the sulfones include dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone. Examples of the sulfolane include sulfolane, 3-methyl sulfolane, and 2,4-dimethyl sulfolane.

  Other co-solvents include water, N-methyl-2-pyrrolidone, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, toluene, xylene, paraffins, polyalkylene glycols such as polyethylene glycol and polypropylene glycol And high molecular weight compounds such as copolymers thereof.

In the present invention, various additives can be added for the purpose of reducing leakage current, improving withstand voltage, and gas absorbent.
Additives include phosphoric acid such as orthophosphoric acid, phosphorous acid, hypophosphorous acid, pyrophosphoric acid, polyphosphoric acid, methyl phosphate, ethyl phosphate, butyl phosphate, isopropyl phosphate, dibutyl phosphate, dioctyl phosphate Compounds, boric acid compounds such as boric acid and complex compounds thereof, random copolymers of polyhydric alcohols such as mannitol, sorbitol, xylitol, pentaerythritol, polyvinyl alcohol, polyethylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene glycol And high molecular compounds typified by block copolymers, nitro compounds such as p-nitrobenzoic acid and m-nitroacetophenone.

  The electrolytic solution of the present invention can be used for, for example, a wound electrolytic capacitor. The capacitor using the electrolytic solution according to the present invention can be manufactured by a usual method. For example, an anode foil subjected to etching treatment and oxide film formation treatment and a cathode foil subjected to etching treatment are wound through a separator. It can be manufactured by a method of turning to form a capacitor element, impregnating the capacitor element with an electrolytic solution, and then storing the capacitor element in a bottomed cylindrical outer case.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited by these Examples.

[Preparation of electrolyte]
A mixed solution of ethylene glycol (EG) and water is used as a solvent, and the dicarboxylic acid represented by the above [Chemical Formula 1] as an electrolyte (a compound having the types of substituents and the numbers of n and m described in Table 1) ) Were used to prepare electrolyte solutions according to the present invention having the electrolyte composition described in Table 1 (Examples 1 to 12).
On the other hand, tridecanedicarboxylic acid, sebacic acid, or 1,6-decanedicarboxylic acid is used as a comparative electrolyte, and a mixed solution of ethylene glycol (EG) and water is used as a solvent. Electrolytic solutions according to conventional examples having an electrolytic solution composition were prepared (conventional examples 1 to 5).

  And about the electrolyte solution of Examples 1-12 and Conventional Examples 1-5, the solubility to a solvent, specific resistance change rate (thermal stability), and withstand voltage were evaluated. The thermal stability was evaluated by the following method.

[Evaluation of thermal stability]
The thermal stability of each of the electrolyte solutions of Examples 1 to 12 and Conventional Examples 1 to 5 was evaluated by the specific resistance change rate after being left at high temperature with respect to the initial specific resistance, using the following formula.

The specific resistance value before being left (initial specific resistance) was measured by measuring the specific resistance of the electrolyte after preparation.
Next, each electrolyte solution was sealed in an ampule tube and allowed to stand at high temperature (105 ° C.-500 hours), and then the specific resistance of the electrolyte solution was measured. This was defined as the specific resistance after standing at high temperature, and the thermal stability was evaluated by the rate of change with respect to the initial specific resistance.

[Evaluation of withstand voltage]
With respect to each of the electrolytic solutions of Examples 1 to 12 and Conventional Examples 1 to 5, the withstand voltage was evaluated by measuring a time-voltage rise curve when a constant current of 2.5 mA was applied to the electrolytic capacitor at 105 ° C. First, the voltage at which spark or scintillation was observed was measured, and this was taken as the withstand voltage. The electrolytic capacitor element used had a case size φ16 × 25 L (mm), a rated voltage of 500 V (chemical conversion voltage 940 V), and a capacitance of 17 μF.
The results are shown in Table 1 below. The specific resistance characteristics in Table 1 are initial specific resistance.

When comparing the results of Examples 1 to 12 and Conventional Example 1 shown in Table 1 above, tridecane dicarboxylic acid (molecular weight: 272) of Conventional Example 1 was added with 4.7% by weight of ethylene glycol and water. The molecular weight (290 to 1302) of the compounds of Examples 1 to 12 is larger than the molecular weight of the compound of Conventional Example 1, but is soluble in the above mixed liquid. . From this, it was confirmed that Examples 1-12 have a structure having a plurality of ether groups, so that the solubility in a solvent is high even if the molecular weight is increased.
Further, from the comparison between Example 12 and Conventional Example 1, the compound of Conventional Example 1 was insoluble in the above mixed solution when 4.7% by weight was added, whereas the compound of Example 12 was 16.8% by weight. However, since it was dissolved in the above mixed solution, it was found that high concentration blending was possible.
Furthermore, from the comparison between Example 1 to Example 12 and Conventional Example 2, the specific resistance change rate of the electrolytic solution of Conventional Example 2 is 177%, whereas the specific resistance of the electrolytic solution of Example 1 to Example 12 is The rate of change was about 20-30%, which was considerably small, and the effect of coordination of functional groups (improved thermal stability) in a compound having steric hindrance to the α-position could be confirmed.
Further, from the comparison between Examples 2 to 4 and Conventional Examples 4 to 5, the withstand voltage of the electrolytes of Conventional Examples 4 to 5 significantly decreases with the increase in the concentration of the compound, whereas the withstand voltage of Examples 2 to 4 is reduced. The voltage characteristics did not decrease greatly even when the concentration of the compound was increased, and the effect of suppressing the withstand voltage decrease due to the increase in concentration was confirmed.
Further, from comparison between Examples 1 to 7, 10, and 12 and Examples 8 and 11, it was found that the specific resistance and the change thereof were reduced in n = 1 to 23 and m = 2 and 4.
From the viewpoint of achieving both withstand voltage characteristics and specific resistance characteristics, m is 2 or 4, n is 2 to 23, and the amount of electrolyte dissolved in the solvent is 4.7 to 16.8% by weight. More preferably.

  In addition, this invention is not restricted to the said Example, When the said electrolyte is used individually or in multiple, the effect similar to the above is acquired.

  In the above embodiment of the present invention, a solvent mixture of ethylene glycol and water was used. However, glycols, lactones, nitriles, alcohols, ethers, ketones, esters, carbonates, sulfones were used. The same effect as described above can be obtained when one or two or more solvents selected from the group consisting of sulfanes and sulfolanes are used.

Furthermore, in the above examples of the present invention, the compound having the chemical formula 1 is a compound in which R ₁ is C ₄ H ₉ or C ₆ H ₁₃ , but a compound in which R ₁ is C ₅ H ₁₁ may be used. The same effect as described above can be obtained.

  By using the electrolytic solution of the present invention, an electrolytic capacitor exhibiting excellent thermal stability and withstand voltage characteristics can be produced, and the electrolytic solution of the present invention is very useful.

Claims (8)

An electrolytic solution for driving an electrolytic capacitor obtained by dissolving an electrolyte in a solvent, wherein the electrolyte is selected from the group consisting of a compound having the following general formula and a salt of the compound: Electrolytic solution for driving electrolytic capacitors.

2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein X in the chemical formula 1 is the following general formula.

_{2. The} electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein R _{1 in the} chemical formula ₁ represents C ₄ H ₉ , C ₅ H ₁₁ or C ₆ H ₁₃ , and R ₂ represents hydrogen.   3. The chemical formula 2 according to claim 2, wherein m is 2 or 4, n is 2 to 23, and the electrolyte is dissolved in the solvent by 4.7 to 16.8% by weight. Electrolytic solution for electrolytic capacitors.   The solvent is selected from the group consisting of glycols, lactones, nitriles, alcohols, ethers, ketones, esters, carbonates, sulfolanes, amides, oxazolidinones, sulfones and water or It is 2 or more types, The electrolyte solution for a drive of the electrolytic capacitor of any one of Claims 1-4 characterized by the above-mentioned.   The electrolytic solution for driving an electrolytic capacitor according to any one of claims 1 to 5, wherein the solvent is a mixed solvent of ethylene glycol and water.   7. The salt according to claim 1, wherein the salt is selected from the group consisting of a primary amine salt, a secondary amine salt, a tertiary amine salt, a quaternary ammonium salt, and an imidazolinium salt. 2. An electrolytic solution for driving an electrolytic capacitor according to claim 1.   An electrolytic capacitor comprising a capacitor element impregnated with the driving electrolyte solution according to claim 1.