JPH09186052A - Electrolyte for driving electrolyte capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an appearance abnormality such as a blown-out explosion- proof valve and a characteristic abnormality by adding acetylene alcohol together with a solute in a solution so as to suppless gas generation caused by a reaction between an anode foil and an electrolyte for driving. SOLUTION: As a main solution of a solvent ethylene glycol is used. And as a main solution of a solute, organic acid, inorganic acid and/or its salt is used. Here, acetylene alcohol together with a solute is added into the solvent. An amount of addition of acetylene alcohol depends on a kind of acetylene alcohol, however, regardless of its kind, a kind of solvent or the like and in terms of effectively protecting an electrode foil, a range of 0.1wt.% to 10wt.% is desirable. Thereby, a reaction between an electrolyte for driving and a negative electrode aluminum can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving electrolyte solution for an aluminum electrolytic capacitor, and more particularly to a composition of the driving electrolyte solution for improving the reliability of the aluminum electrolytic capacitor. .

[0002]

2. Description of the Related Art In general, an aluminum electrolytic capacitor has a separator paper between an anode foil obtained by etching a high-purity aluminum foil and anodizing its surface and a cathode foil obtained by etching the aluminum foil. A structure in which a capacitor element wound so as to be interposed is impregnated with an electrolytic capacitor driving electrolytic solution (hereinafter referred to as a driving electrolytic solution), and then the capacitor element is housed in an aluminum case and sealed by an elastic sealing body. It has become.

In recent years, for the purpose of downsizing and weight saving of electronic equipment, electronic parts are also required to be downsized and lightened. In order to meet such requirements, aluminum electrolytic capacitors have a high capacity of anode foil. Is being promoted.

[0004]

Since the capacity of the aluminum electrolytic capacitor corresponds to the composite capacity of the anode foil and the cathode foil, when the capacity of the anode foil is increased, the cathode foil is increased by that amount. It is also necessary to increase the capacity of. The capacity of such a cathode foil is increasing day by day due to the expansion of the effective surface area of the electrode foil as a result of the improvement of the etching technology, but with this, the surface of the cathode foil becomes active and is activated in the atmosphere or in the driving electrolyte solution. It tends to be easily oxidized. As a result, when an aluminum electrolytic capacitor using a cathode foil with an expanded surface area is used for a long time under conditions where surrounding components generate heat, hydrogen gas is generated inside the aluminum case due to the reaction between the cathode foil and the driving electrolyte. Occurs, and if significant, the explosion-proof valve operates.

Therefore, conventionally, a hydrogen gas absorbent such as a nitro compound is blended with the driving electrolyte so that the generated hydrogen gas is absorbed by the nitro compound or the like to prevent an abnormal increase in the internal pressure in the aluminum case. doing. However, even with this measure, it is becoming difficult to sufficiently suppress the increase in the amount of gas generated due to the increase in the surface area of the cathode foil.

[0006] In view of the above problems, an object of the present invention is to provide:
An object of the present invention is to provide a driving electrolytic solution for an aluminum electrolytic capacitor, which can suppress gas generation due to a reaction between a cathode foil and a driving electrolytic solution and prevent abnormal appearance and characteristic abnormalities such as operation of an explosion-proof valve.

[0007]

In order to solve the above problems, the present invention is characterized by adding acetylene alcohol together with a solute to a solvent in an electrolytic solution for driving an aluminum electrolytic capacitor.

According to the results of repeated experiments, the driving electrolytic solution thus constructed tends to suppress the reaction with the electrode foil. The reason for this is considered as follows. First, acetylene alcohol is generally represented by Chemical Formula 1 or Chemical Formula 2, and the triple bond portion of the acetylene alcohol has a very high electron density, and the active hydrogen atom of the hydroxyl group adjacent to the π electron of this portion is on the metal surface (electrode It is oriented and retained on the foil surface). This retained acetylene alcohol further forms a multi-layer. That is, as a result of the formation of a polymolecular layer of acetylene alcohol on the surface of the cathode foil made of aluminum foil, the polymolecular layer prevents the reaction between the driving electrolytic solution and the cathode aluminum and suppresses gas generation.

[0009]

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[0010]

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As the acetylene alcohol which can be added to the driving electrolyte according to the present invention, 1-hexyne-3-ol, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyne-3- All, 3,6-dimethyl-4-
Octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,5-dimethyl-1-hexyne-3-ol, 2,5-dimethyl-
There are 3-hexyne-2,5-diol and the like, but from the viewpoint of achieving the object of the present invention, an acetylene alcohol having an alkyl group on only one side of the triple bond represented by Chemical Formula 1. Since the addition of the above has a stronger bond with the metal, the addition of the acetylene alcohol having such a structure is suitable.

In the present invention, ethylene glycol can be used as the main solvent of the solvent, and organic acid, inorganic acid and / or salt thereof can be used as the main solute of the solute. . Here, as solute, azelaic acid, adipic acid, 1,6
-Carboxylic acids such as decane dicarboxylic acid, aromatic carboxylic acids such as benzoic acid, salicylic acid and phthalic acid, inorganic acids such as boric acid and salts thereof can be used.

In addition, for example, a mixed solvent of ethylene glycol and water is used as the solvent, and an electrolyte solution for driving using adipic acid and / or a salt thereof as the solute, for example, does not contain acetylene alcohol. It is valid.

The amount of acetylene alcohol added depends on the type of acetylene alcohol, but from the viewpoint of effectively protecting the electrode foil, regardless of the type of acetylene alcohol, the type of solvent, etc., from 0.1% by weight to 10% by weight. It is preferably in the range of up to wt%. That is, when the amount of acetylene alcohol added is less than 0.1% by weight, the formation of a multi-molecular layer of acetylene alcohol on the cathode foil is insufficient. The spark voltage of the electrolytic solution tends to be lowered.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an electrolytic solution for driving an electrolytic capacitor to which the present invention is applied will be described. Each of the following examples will be described as an example applied to the most general aluminum electrolytic capacitor, and therefore, illustration and detailed description of the structure of the aluminum electrolytic capacitor will be omitted, but the windings generally manufactured by the following steps. This is an example applied to an aluminum electrolytic capacitor having a structure.

In the aluminum electrolytic capacitor of this example, an aluminum foil is electrochemically etched, anodized in a neutral or weakly acidic aqueous solution such as phosphate to form an oxide film on the surface, and then the electrode is formed. Attach the lead tab for the drawer to form the aluminum anode foil. on the other hand,
After performing an etching treatment on the aluminum foil, a lead tab for drawing out an electrode is attached to produce an aluminum cathode foil. Next, the anode foil, the cathode foil, and the electrolytic paper are overlapped and wound so that the separator paper is interposed between the anode foil and the cathode foil, and the capacitor element is manufactured. Then, after the capacitor element is impregnated with the driving electrolytic solution, it is housed in, for example, a bottomed tubular aluminum case, and then the case opening is sealed with an elastic sealing body.

With respect to the aluminum electrolytic capacitor manufactured by such a method, as the driving electrolytic solution,
In this example, the electrolytic solution having the composition shown in Table 1 is used.

[0018]

[Table 1]

Here, the main solvent of the driving electrolytic solution is dissolved using ethylene glycol as a main solvent and ammonium benzoate as a solute. Further, among the respective electrolytic solution compositions, Sample A is the driving electrolytic solution according to Conventional Example 1, and acetylene alcohol was added to and dissolved in this composition (Samples B, C, D and E). Is a driving electrolytic solution to which the present invention is applied.

Further, in this example, regarding the aluminum electrolytic capacitor having the same structure as described above, the electrolytic solution having the composition shown in Table 2 was also examined as the driving electrolytic solution.

[0021]

[Table 2]

Here, each of the driving electrolytic solutions is a mixed solvent of ethylene glycol and water, and is dissolved using ammonium adipate as a solute. In addition, among the respective electrolytic solution compositions, sample H is the electrolytic solution according to Conventional Example 2, and electrolytic solution in which acetylene alcohol was added and dissolved based on this composition (Samples I, J, K, L, M) Is a driving electrolytic solution to which the present invention is applied.

With respect to the electrolytic solution, a rating of 20 was obtained by using each of the driving electrolytic solutions according to the conventional example and the example shown in Table 1.
An aluminum electrolytic capacitor of 0 V-100 μF was manufactured as a prototype. Further, an aluminum electrolytic capacitor having a rating of 35V-1000 μF was prototyped using the driving electrolytic solutions according to the conventional example and the example shown in Table 2.

A rated DC voltage was continuously applied to these test capacitors in a thermostatic chamber maintained at 105 ° C. for 5000 hours, and the operation time of the explosion-proof valve and the number of operations of the explosion-proof valve were measured. Regarding the aluminum electrolytic capacitor in which the explosion-proof valve did not operate, the electrical characteristics after the test were measured. Regarding the electrical characteristics, the capacity at 120 Hz, Tan δ, and the current (leakage current) flowing through the aluminum electrolytic capacitor after applying the rated DC voltage for 1 minute were measured at 20 ° C. Table 3 shows the results.

[0025]

[Table 3]

As is clear from the results shown in Table 3, the aluminum electrolytic capacitors using the conventional driving electrolytes (Samples A and H) were tested by a load test in an atmosphere of 105 ° C. by the time 5000 hours had elapsed. The explosion-proof valve is activated. On the other hand, the aluminum electrolytic capacitor using the driving electrolyte solution (Samples B, C, D, E, and Samples I, J, K, L, M) to which the present invention is applied has a temperature of 105 ° C. In the load test, the explosion-proof valve did not operate even after 5000 hours, and it was confirmed that the stability at high temperature was superior to that of aluminum electrolytic capacitors using conventional electrolytes (Samples A and H). did it. Therefore, the aluminum electrolytic capacitor using the electrolytic solution of the present invention,
Even when used under conditions where surrounding parts generate heat, the explosion-proof valve will not operate for a long time.
Maintains good electrical characteristics and has high reliability.

As shown in each of the examples, an effect of enhancing reliability is recognized even when the amount of acetylene alcohol of the present invention added is 0.5% by weight, and the effect tends to increase as the amount of addition increases. . However, if the addition amount of acetylene alcohol is less than 0.1% by weight, the effect becomes small, while if the addition amount exceeds 10% by weight, the spark voltage of the electrolytic solution tends to decrease. Is 0.
It can be said that the range of 1% by weight to 10% by weight is preferable.

In the above embodiments, an example using an ethylene glycol-based solvent has been described. However, for example, acetylene alcohol may be added to a mixed solvent system of γ-butyrolactone and ethylene glycol. Even in this case, there is an advantage that the reaction between the electrode foil and a small amount of water contained in the driving electrolytic solution can be prevented.

[0029]

As described above, the driving electrolytic solution according to the present invention is characterized by the addition of acetylene alcohol, and the addition of such acetylene alcohol suppresses the reaction between the electrolytic solution and the electrode foil. Tend to do. Therefore,
The aluminum electrolytic capacitor using the driving electrolytic solution to which the present invention is applied has an effect that the explosion-proof valve does not operate for a long time even when used in a high-temperature atmosphere, maintains good characteristics, and is highly reliable. Play.

Claims (4)

[Claims] 1. An electrolytic solution for driving an aluminum electrolytic capacitor, wherein an acetylene alcohol together with a solute is added to the solvent in the electrolytic solution for driving an aluminum electrolytic capacitor. 2. The electrolytic capacitor driving device according to claim 1, wherein the main solvent of the solvent is ethylene glycol, and the main solute of the solvent is an organic acid, an inorganic acid and / or a salt thereof. Electrolyte. 3. The electrolytic capacitor driving method according to claim 1, wherein the solvent is a mixed solvent of ethylene glycol and water, and the main solute is adipic acid and / or a salt thereof. Electrolyte. 4. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the amount of the acetylene alcohol added is in the range of 0.1% by weight to 10% by weight. .