JP2007005570A - Driving electrolyte of electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte for an aluminum electrolytic capacitor which enables it to be reduced in resistivity and increased in withstand voltage simultaneously. <P>SOLUTION: Carboxylic acids, such as adipic acid, sebacic acid, azelaic acid, 1,6-decane dicarboxylic acid, etc., or their ammonium salts, are blended into a solvent whose main components are ethylene glycol etc. Furthermore, 0.10 to 5.00 wt% t-butyl peroxy laurate represented by a following chemical formula is blended besides them. By this setup, a chemical reaction can be restrained from taking place between an electrolyte and an electrode foil, so that the electrolyte can be increased in withstand voltage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement of an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as an electrolytic solution), and particularly relates to an electrolytic solution having improved withstand voltage.

Conventionally, in an electrolytic solution for medium and high pressure aluminum electrolytic capacitors, a higher dibasic acid or an ammonium salt thereof, boric acid or an ammonium salt thereof, and a polyhydric alcohol such as mannitol are blended in a solvent such as ethylene glycol. It is known that boric acid and polyhydric alcohols form an ester compound, and the withstand voltage of the electrolytic solution is improved due to its structural characteristics. Furthermore, polyvinyl alcohol which is a synthetic polymer may be blended (see, for example, Patent Documents 1 to 3).
Japanese Examined Patent Publication No. 7-48459 (page 1-4) Japanese Patent Publication No. 7-48460 (page 1-3) Japanese Examined Patent Publication No. 7-63047 (page 1-4)

  However, mannitol, sorbitol, etc. having about 6 carbon atoms are slow to improve the withstand voltage of the electrolyte even if the blending amount is increased, and in order to greatly improve the withstand voltage, a large amount needs to be blended. As a result, the specific resistance is significantly increased. Polyvinyl alcohol, on the other hand, can improve the withstand voltage of the electrolyte solution by adding a smaller amount than mannitol, but it cannot be added in a large amount because it has extremely low solubility in a solvent mainly composed of ethylene glycol. There is a problem that stirring is required for a long time. In addition, since polyhydric alcohols may cause an ester reaction with higher dibasic acids which are main solutes, there is a problem in that the characteristic change of the electrolytic solution itself becomes large.

  In view of the above problems, an object of the present invention is to provide an electrolytic solution for an aluminum electrolytic capacitor capable of achieving both a reduction in specific resistance and an increase in withstand voltage.

  The present invention has been found as a result of various studies to solve the above-described problems, and has been found that t-butyl peroxylaurate has an ether group. It is intended to suppress the chemical reaction and increase the withstand voltage.

  That is, in the electrolytic solution for an aluminum electrolytic capacitor of the present invention, at least carboxylic acid or a salt thereof and t-butyl peroxylaurate represented by the following chemical formula are blended in a solvent mainly composed of ethylene glycol. It is characterized by.

  In this invention, it is preferable that the compounding quantity of t-butyl peroxy laurate is 0.10 to 5.00 wt% with respect to the whole electrolyte solution.

  In the present invention, examples of the carboxylic acid include polycarboxylic acids azelaic acid, 2-methyl azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid, and 7-vinylhexadecene-1,16. -Dicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, maleic acid, fumaric acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid Thiodipropionic acid and the like, and oxycarboxylic acid such as glycolic acid, lactic acid, tartaric acid, salicylic acid, mandelic acid and the like, and as monocarboxylic acid, formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, Caproic acid, enanthic acid, caprylic acid, pelargonic acid, lauric acid, myristic acid, stearin , Behenic acid, acrylic acid, methacrylic acid, oleic acid, benzoic acid, p-nitrobenzoic acid, anisic acid, cumic acid, cinnamic acid, naphthoic acid, and the like. In addition, borodisoxalic acid, borodiglycolic acid, Examples thereof include borodisalicylic acid and ethylene glycol borate.

  Examples of carboxylic acid salts include ammonium salts, primary amine salts such as methylamine, ethylamine, and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine, and diethylamine, trimethylamine, diethylmethylamine, and ethyldimethylamine. , Tertiary amine salts such as triethylamine N, N-dimethyl-N- (2-methoxyethyl) amine, quaternary ammonium salts such as tetramethylammonium, triethylmethylammonium and tetraethylammonium, and molten salts such as imidazolinium salts It can be illustrated.

  As a co-solvent mixed with ethylene glycol, glycols such as propylene glycol, lactones such as γ-butyrolactone and N-methyl-2-pyrrolidone, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, Amides such as N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N, N-diethylacetamide, hexamethylphosphoricamide, ethylene carbonate, propylene carbonate, isobutylene carbonate, etc. Examples thereof include carbonic acids, nitriles such as acetonitrile, oxides such as dimethyl sulfoxide, ethers, ketones, esters, sulfolane, sulfolane derivatives, water and the like. These solvents can be used by mixing not only one type but also two or more types.

  Various additives can be added to the electrolytic solution according to the present invention for the purpose of reducing leakage current, improving withstand voltage, and absorbing gas. Examples of additives include phosphoric acid compounds, boric acid compounds, polyhydric alcohols, polyvinyl alcohol, polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene glycol random copolymers and block copolymers. A molecular compound, a nitro compound, etc. are mentioned.

In the electrolytic solution according to the present invention, at least carboxylic acid or a salt thereof and t-butyl peroxylaurate are blended in a solvent mainly composed of ethylene glycol, There is an effect of improving the withstand voltage of the electrolyte.
The reason is that in the electrolytic solution containing ethylene glycol as the main solvent, the ether group portion of t-butyl peroxylaurate reacts with the oxide film of the electrode foil to form a water-resistant film. It is considered that the chemical reaction with the foil is suppressed and the withstand voltage can be improved.
Moreover, since t-butyl peroxylaurate is highly soluble in a solvent containing ethylene glycol as a main component, t-butyl peroxylaurate can be added in a large amount, and when the electrolytic solution is prepared, Stirring is short.
Furthermore, t-butyl peroxylaurate has little esterification reaction with the main solute carboxylic acid.
Therefore, according to the electrolytic solution of the present invention, it is possible to reduce both the specific resistance and the withstand voltage.
Moreover, since the aluminum electrolytic capacitor using the electrolyte solution according to the present invention is excellent in thermal stability, the reliability of the aluminum electrolytic capacitor can be improved.

  Hereinafter, based on an Example, this invention is demonstrated more concretely. First, after preparing electrolyte solution with the composition shown in Table 1 and Table 2, the specific resistance of the electrolyte solution at 30 ° C. and the spark generation voltage at 85 ° C. (withstand voltage of electrolyte solution) were measured. The results are shown in Tables 1 and 2.

  From Table 1 and Table 2, it can be seen that the withstand voltages of the electrolytic solutions according to Examples 1 to 10 of the present invention are improved compared to the electrolytic solution according to Conventional Example 1. Moreover, the electrolyte solution which concerns on Examples 6-10 of this invention has a withstand voltage higher than the prior art example 4 which added polyvinyl alcohol as a withstand voltage improver, and a specific resistance is equivalent or low.

  Here, when the blending amount of t-butyl peroxylaurate is less than 0.10 wt% (Example 1), the effect of improving the withstand voltage is not sufficient, and the ratio exceeds 5.00 wt% (Example 5). High resistance makes it unsuitable for low resistivity applications. Therefore, the blending amount of t-butyl peroxylaurate is preferably in the range of 0.10 to 5.00 wt% with respect to the entire electrolyte solution.

  In addition, this invention is not limited to an Example, It is an Example also in the electrolyte solution which mixed the various solute illustrated previously individually or in mixture, the electrolyte solution which added the other additive, and the subsolvent. Had the same effect.

Claims (2)

An electrolytic solution for driving an electrolytic capacitor, characterized in that at least a carboxylic acid or a salt thereof and t-butyl peroxylaurate represented by the following chemical formula are blended in a solvent mainly composed of ethylene glycol. .

  An electrolytic solution for driving an electrolytic capacitor, wherein the amount of t-butyl peroxylaurate according to claim 1 is 0.10 to 5.00 wt% with respect to the entire electrolytic solution.