JP2002280266A - Electrolyte for drive for electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte for drive for electrolytic capacitor, with which tanδ increase/short puncture of an electrolytic capacitor can be suppressed over a long time. SOLUTION: Higher dibasic acid or salt thereof, boric acid or ammonium salt thereof and methylene bisdialkylphenol, especially, 2,2'-methylenebis(6-tert- butyl-4-methylphenol) (chemical formula 1) or 4,4'-methylenebis(2,6-di-tert- butylphenol) (chemical formula 2) in 0.10 to 5.00 wt.% are dissolved in a solvent with ethylene glycol as the main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as an electrolytic solution).

[0002]

2. Description of the Related Art Conventionally, in a medium pressure aluminum electrolytic capacitor, a higher dibasic acid or its ammonium salt, boric acid or its ammonium salt, and a sugar alcohol such as mannitol are dissolved in a solvent such as ethylene glycol. Electrolytes have been used. It is known that a higher dibasic acid or boric acid and a sugar alcohol form an ester compound, thereby improving the withstand voltage of an electrolytic solution due to its structural characteristics. However, this ester compound generates a small amount of amides due to heat generation of the electrolytic capacitor and the like, and the product of the radical chain thermal oxidation reaction between the amides and oxygen remaining in the electrolytic solution causes a rise in the specific resistance of the electrolytic solution. There was a problem. In addition, although the withstand voltage can be improved by adding polyvinyl alcohol, there is a problem that the main chain of polyvinyl alcohol is cut by oxygen radicals generated inside the product, and the withstand voltage of the electrolytic solution is reduced.

[0003]

It has been proposed to add an antioxidant such as catechol to the electrolytic solution in order to suppress the radical chain thermal oxidation reaction and the breakage of the main chain of polyvinyl alcohol. Is high and reacts by taking in oxygen in the air when preparing the electrolyte,
When a capacitor element is impregnated with an electrolytic solution and sealed in a case, most of the catechol reacts and there is a problem that the effect is not maintained for a long time.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an electrolyte solution containing methylenebisdialkylphenol, especially 2,2'-methylenebis (6-methylenebis) diphenol.
By dissolving tert-butyl-4-methylphenol) or 4,4′-methylenebis (2,6-di-tert-butylphenol), the amide in the electrolytic capacitor can be formed without lowering the withstand voltage of the electrolytic solution. It is an object of the present invention to provide an electrolytic solution capable of suppressing oxidation reactions of various kinds and a main chain scission reaction of polyvinyl alcohol for a long period of time and suppressing an increase in tan δ and occurrence of short puncture of a product in a high temperature load test. That is, in a solvent containing ethylene glycol as a main component, a higher dibasic acid or a salt thereof, boric acid or an ammonium salt thereof, and methylenebisdialkylphenol are dissolved, and the electrolytic solution for driving an electrolytic capacitor is characterized by the following: is there.

The methylenebisdialkylphenol is 2,2'-methylenebis (6-tert-butyl-4-methylphenol) (formula 3), 2,2'-methylenebis (6-tert-butyl-3-) Methylphenol), 2,2′-methylenebis (6-tert-butyl-5-methylphenol), 2,2′-methylenebis (5-tert-butyl-3-methylphenol),
2,2'-methylenebis (5-tert-butyl-4-
Methylphenol), 2,2′-methylenebis (5-t
tert-butyl-6-methylphenol), 2,2'-
Methylenebis (4-tert-butyl-3-methylphenol), 2,2′-methylenebis (4-tert-butyl-5-methylphenol), 2,2′-methylenebis (4-tert-butyl-6-methylphenol) ),
2,2′-methylenebis (3-tert-butyl-4-
Methylphenol), 2,2′-methylenebis (3-t
tert-butyl-5-methylphenol), 2,2'-
Methylenebis (3-tert-butyl-6-methylphenol), 4,4′-methylenebis (2,6-di-te
rt-butylphenol) (Formula 4), 4,4′-methylenebis (2,5-di-tert-butylphenol),
4,4′-methylenebis (2,3-di-tert-butylphenol), 4,4′-methylenebis (3,5-di-tert-butylphenol), 4,4′-methylenebis (3,6-di-tert) -Butyl phenol) for driving an electrolytic capacitor.

[0006]

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[0007]

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Further, there is provided an electrolytic solution for driving an electrolytic capacitor, wherein the dissolved amount of the methylenebisdialkylphenol is 0.10 to 5.00 wt%.

Further, there is provided an electrolytic solution for driving an electrolytic capacitor, wherein at least one of mannitol, sorbitol, dulcitol and polyvinyl alcohol is added to the electrolytic solution for driving an electrolytic capacitor.

The higher dibasic acids include adipic acid, azelaic acid, sebacic acid, 1,6-decanedicarboxylic acid,
Examples thereof include 5,6-decanedicarboxylic acid and 7-vinylhexadecene-1,16-dicarboxylic acid.

The salts of higher dibasic acids include ammonium salts, primary amine salts such as methylamine, ethylamine and t-butylamine, secondary amine salts such as dimethylamine, ethylmethylamine and diethylamine, and trimethylamine. And tertiary amine salts such as diethylmethylamine, ethyldimethylamine and triethylamine, and quaternary ammonium salts such as tetramethylammonium, triethylmethylammonium and tetraethylammonium.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Methylenebisdialkylphenols, especially 2,2'-methylenebis (6-tert-butyl-4-methylphenol) and 4,4'-methylenebis (2,6-di-tert-butylphenol), , A polyoxy compound having a structure in which an alkyl group is added to bisphenol, and two OH groups in the molecule react preferentially with the residual oxygen in the electrolytic capacitor, and have an effect of eliminating the radical property of oxygen, so that amide is used. Oxidative reaction and main chain scission reaction of polyvinyl alcohol can be suppressed. Also, compared to catechol having only one benzene ring, it has a higher melting point and boiling point, so it has better thermal stability, and its relatively low reactivity makes it possible to carry out oxidation reaction of amides and main chain cleavage reaction of polyvinyl alcohol for a long time. Since it can be suppressed, the initial characteristics of the product can be maintained for a long time.
Furthermore, even in the case of an electrolytic solution containing no sugar alcohol or polyvinyl alcohol in the solute, the methylenebisdialkylphenol suppresses the reaction between the electrode foil and the water in the electrolytic solution, and the initial characteristics of the product can be maintained for a long time.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. Electrolyte solutions were prepared using the compositions shown in Tables 1 and 2, and the specific resistance of the electrolyte solution at 30 ° C. and the spark generation voltage (withstand voltage) at 85 ° C. were measured.

[0014]

[Table 1]

[0015]

[Table 2]

After the electrolytic solution shown in Tables 1 and 2 was impregnated into the capacitor element, it was sealed together with a sealing rubber in an aluminum outer case, and had a diameter of 35.0 mm and a length of 35.0 mm.
Ten aluminum electrolytic capacitors each having a rated voltage of 400 V and a capacitance of 390 μF were manufactured and subjected to aging treatment. The initial values of these products were applied at a rated voltage in a high-temperature bath at 105 ° C., taken out at regular intervals, and the changes in tan δ of the products were investigated. The results shown in Table 3 were obtained.

[0017]

[Table 3]

In Conventional Example 1, tan δ increased with time, and short puncture occurred due to a decrease in withstand voltage by 2000 hours. In Conventional Example 2 in which catechol was dissolved, no change was observed in the tan δ value up to 500 hours, but tan δ increased greatly probably because all of the catechol had reacted. On the other hand, Examples 1 to 5 in which 2,2'-methylenebis (6-tert-butyl-4-methylphenol) of the present invention was dissolved and 4,4'-methylenebis (2,6-di-tert-butylphenol). In Examples 6 to 10 in which is dissolved, the occurrence of short puncture due to an increase in tan δ and a decrease in withstand voltage of the electrolytic solution is suppressed, and the effect increases with an increase in the amount of addition.

The amount of the methylenebisdialkylphenol dissolved is preferably in the range of 0.10 to 5.00 wt%.
If it is less than 0.10 wt%, no effect of suppressing the increase of tan δ is seen, and if it exceeds 5.00 wt%, the specific resistance rises remarkably, so that it is not suitable for applications requiring low specific resistance.

In the examples, 2,2′-methylenebis (6-te) is used as methylenebisdialkylphenol.
rt-butyl-4-methylphenol) and 4,4′-methylenebis (2,6-di-tert-butylphenol) were used.
t-butyl-3-methylphenol), 2,2′-methylenebis (6-tert-butyl-5-methylphenol), 2,2′-methylenebis (5-tert-butyl-3-methylphenol), 2, 2'-methylenebis (5-tert-butyl-4-methylphenol),
2,2'-methylenebis (5-tert-butyl-6-
Methylphenol), 2,2′-methylenebis (4-t
tert-butyl-3-methylphenol), 2,2'-
Methylenebis (4-tert-butyl-5-methylphenol), 2,2′-methylenebis (4-tert-butyl-6-methylphenol), 2,2′-methylenebis (3-tert-butyl-4-methylphenol) ),
2,2′-methylenebis (3-tert-butyl-5-
Methylphenol), 2,2′-methylenebis (3-t
tert-butyl-6-methylphenol), 4,4'-
Methylenebis (2,5-di-tert-butylphenol), 4,4′-methylenebis (2,3-di-tert
-Butylphenol), 4,4'-methylenebis (3,
Use of 5-di-tert-butylphenol) or 4,4′-methylenebis (3,6-di-tert-butylphenol) had the same effect as in the example.

[0021]

As described above, the methylenebisdialkylphenol according to the present invention, particularly 2,2'-methylenebis (6-tert-butyl-4-methylphenol),
2,2′-methylenebis (6-tert-butyl-3-
Methylphenol), 2,2′-methylenebis (6-t
tert-butyl-5-methylphenol), 2,2'-
Methylene bis (5-tert-butyl-3-methylphenol), 2,2′-methylenebis (5-tert-butyl-4-methylphenol), 2,2′-methylenebis (5-tert-butyl-6-methylphenol) ),
2,2′-methylenebis (4-tert-butyl-3-
Methylphenol), 2,2′-methylenebis (4-t
tert-butyl-5-methylphenol), 2,2'-
Methylene bis (4-tert-butyl-6-methylphenol), 2,2′-methylenebis (3-tert-butyl-4-methylphenol), 2,2′-methylenebis (3-tert-butyl-5-methylphenol) ),
2,2′-methylenebis (3-tert-butyl-6-
Methylphenol), 4,4'-methylenebis (2,
6-di-tert-butylphenol), 4,4′-methylenebis (2,5-di-tert-butylphenol), 4,4′-methylenebis (2,3-di-tert)
-Butylphenol), 4,4'-methylenebis (3,
The electrolytic solution in which 5-di-tert-butylphenol) and 4,4′-methylenebis (3,6-di-tert-butylphenol) are dissolved increases the product tan δ in a high-temperature load test without lowering the withstand voltage of the electrolytic solution. And short puncture of the product can be suppressed.

Claims (4)

[Claims] 1. A method for driving an electrolytic capacitor, comprising dissolving a higher dibasic acid or a salt thereof, boric acid or an ammonium salt thereof, and a methylenebisdialkylphenol in a solvent containing ethylene glycol as a main component. Electrolyte. 2. The method according to claim 1, wherein the methylenebisdialkylphenol is 2,2′-methylenebis (6-tert.
-Butyl-4-methylphenol) (formula 1), 2,2 ′
-Methylenebis (6-tert-butyl-3-methylphenol), 2,2′-methylenebis (6-tert-
Butyl-5-methylphenol), 2,2′-methylenebis (5-tert-butyl-3-methylphenol), 2,2′-methylenebis (5-tert-butyl-4-methylphenol), 2,2 ′ -Methylenebis (5-tert-butyl-6-methylphenol),
2,2′-methylenebis (4-tert-butyl-3-
Methylphenol), 2,2′-methylenebis (4-t
tert-butyl-5-methylphenol), 2,2'-
Methylene bis (4-tert-butyl-6-methylphenol), 2,2′-methylenebis (3-tert-butyl-4-methylphenol), 2,2′-methylenebis (3-tert-butyl-5-methylphenol) ),
2,2′-methylenebis (3-tert-butyl-6-
Methylphenol), 4,4'-methylenebis (2,6
-Di-tert-butylphenol) (formula 2), 4,
4'-methylenebis (2,5-di-tert-butylphenol), 4,4'-methylenebis (2,3-di-t
tert-butylphenol), 4,4′-methylenebis (3,5-di-tert-butylphenol),
An electrolytic solution for driving an electrolytic capacitor, which is 4'-methylenebis (3,6-di-tert-butylphenol). Embedded image Embedded image 3. An electrolytic solution for driving an electrolytic capacitor, wherein the amount of the methylenebisdialkylphenol according to claim 1 is 0.10 to 5.00 wt%. 4. An electrolytic solution for driving an electrolytic capacitor, characterized in that at least one of mannitol, sorbitol, dulcitol and polyvinyl alcohol is added to the electrolytic solution for driving an electrolytic capacitor according to claim 1.