JP4555168B2 - Electrolytic solution for driving electrolytic capacitors - Google Patents

Description

  The present invention relates to an improvement in an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as an electrolytic solution), and particularly relates to an electrolytic solution with improved reliability.

In an electrolytic solution for driving an aluminum electrolytic capacitor, an organic carboxylic acid or a salt thereof is added to a mixed solvent of water and ethylene glycol, and a polyhydric alcohol is added to alleviate deterioration of the electrode foil due to the electrolytic solution. Has been proposed (see, for example, Patent Document 1).
JP 2001-185458 A

  However, there is a problem that polyhydric alcohol has a slow improvement in reliability with respect to the amount added, and that when the polyhydric alcohol is added in a large amount, the specific resistance is remarkably increased.

  In view of the above problems, an object of the present invention is to provide an electrolytic solution capable of reducing both the specific resistance and improving the reliability of an aluminum electrolytic capacitor.

  The present invention focuses on the formation of a water-repellent film by combining an alkyl ketene dimer with an aluminum foil, and solves the above problems by adapting the characteristics of the film to an electrolytic solution.

  That is, in the electrolytic solution for driving an aluminum electrolytic capacitor according to the present invention, at least an organic carboxylic acid or a salt thereof and an alkyl ketene dimer represented by the following chemical formula in a solvent mainly composed of ethylene glycol and water. It is characterized by being blended.

  The blending amount of the alkyl ketene dimer is preferably 0.5 to 3.0 wt% with respect to the entire electrolyte solution.

  Organic carboxylic acids include formic acid, acetic acid, acrylic acid, propionic acid, lactic acid, butyric acid, valeric acid, gluconic acid, benzoic acid, p-nitrobenzoic acid, anthranilic acid, salicylic acid, gentisic acid, gallic acid, malonic acid , Succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, oxalic acid, tolutronic acid, fumaric acid, maleic acid, citraconic acid, malic acid, tartaric acid, phthalic acid, borolic acid Examples thereof include disalicylic acid, citric acid, pyromellitic acid, naphthoic acid, 1,6-decanedicarboxylic acid, 5,6-decanedicarboxylic acid, and 7-vinylhexadecene-1,16-dicarboxylic acid.

  Furthermore, organic carboxylic acid salts include primary amine salts such as methylamine, ethylamine and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine and diethylamine, trimethylamine, diethylmethylamine, ethyldimethylamine and triethylamine. And tertiary amine salts such as tetramethylammonium, triethylmethylammonium and tetraethylammonium, and ammonium salts.

  In the electrolytic solution according to the present invention, since the solvent contains water, the specific resistance of the electrolytic solution can be reduced. Moreover, since alkyl ketene dimer is blended in the electrolytic solution, it is possible to suppress the formation of hydrated oxide on the surface of the aluminum electrode foil, and to suppress the rate of change in capacitance and tan δ of the aluminum electrolytic capacitor. Thus, the reliability of the aluminum electrolytic capacitor can be improved.

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

  Next, 10 aluminum electrolytic capacitors each having a diameter of 10.0 mm, a length of 12.5 mm, a rated voltage of 6.3 V, and a capacitance of 1800 μF were produced using the electrolytic solution shown in Table 1. The rated voltage was applied to these products in a constant temperature bath at 105 ° C. for 2000 hours, and then the capacitance and tan δ were measured. The results shown in Table 2 were obtained.

  As is clear from Tables 1 and 2, in the aluminum electrolytic capacitors using the electrolytic solutions according to Examples 1 to 8 to which the alkyl ketene dimer was added, water was added to the solvent to reduce the specific resistance of the electrolytic solution. Even in this case, the resistivity is lower than that of the conventional examples 1 and 2, the withstand voltage is almost the same, and the rate of change in capacity and tan δ after 2000 hours are suppressed in a 105 ° C. constant temperature bath. I understand that.

  Here, the blending amount of the alkyl ketene dimer with respect to the electrolytic solution is preferably in the range of 0.5 to 3.0 wt%. When the blending amount is less than 0.5 wt%, the effect of suppressing the increase in capacity change rate and tan δ is small, and when it exceeds 3.0 wt%, the capacity change rate is suppressed, but the tan δ change rate tends to increase.

  In addition, this invention is not limited to the said Example, It is also about the electrolyte solution which mixed the electrolyte solution which mix | blended various solutes described previously individually or plurally, added the other additive, and the mixed solvent. The same effect as in the example was obtained.

Claims (2)

An electrolytic solution for driving an electrolytic capacitor, characterized in that at least an organic carboxylic acid or a salt thereof and an alkyl ketene dimer represented by the following chemical formula are blended in a solvent containing water and ethylene glycol as main components: .

  2. The electrolytic solution for driving an electrolytic capacitor, wherein the blending amount of the alkyl ketene dimer according to claim 1 is 0.5 to 3.0 wt% with respect to the entire electrolytic solution.