JP2000068154A - Electrolytic-capacitor driving electrolyte and electrolytic capacitor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make extensible at a high temperature the life time of an electrolytic-capacitor driving electrolyte, by adding to an organic solvent one or more kinds of solutes made of inorganic and organic acids or these salts, and by dissolving additively a cationic interfacial activator to the solvent to form the electrolyte. SOLUTION: Adding one or more kinds of solutes made of inorganic and organic acids or these salts to an organic solvent, a cationic interfacial activator is dissolved additively in the solvent to use the resultant as an electrolytic- capacitor driving electrolyte. Hereupon, the structure of the cationic interfacial activator is formed based on the equation of +N-(R1)(R2)(R3)-(CH2-O)m-H (where R1-R3 are substituents selected from among -C2H4OH, -CH2OH, -CH3, -C2H5, and -H, and R1-R3 may be selected simultaneously to be the same substituent, and further, m is an arbitrary natural number.). Still, it is not desirable that the cationic interfacial activator of -C2H4OH is added independently to the solvent of ethylene glycol, because its solubility in ethylene glycol is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic solution for driving an electrolytic capacitor and an electrolytic capacitor using the same.

[0002]

2. Description of the Related Art A driving electrolyte used for an electrolytic capacitor usually contains an organic compound such as .gamma.-butyrolactone or ethylene glycol as a main solvent, and an inorganic acid such as boric acid is added as a solute to increase the discharge voltage. However, in an environment exceeding 100 ° C., the water of crystallization in boric acid evaporates as water vapor, which raises the internal pressure in the package of the electrolytic capacitor, and destroys it. there were. As means for solving this, aromatic carboxylic acids such as benzoic acid and phthalic acid, adipic acid, azelaic acid, butyloctane diacid (Japanese Patent Publication No. 60-13293), 5,6-decanedicarboxylic acid ( Japanese Patent Publication No. Sho 63-15738), and a driving electrolyte solution using an aliphatic carboxylic acid such as a dibasic acid having a side chain (Patent Registration No. 2681202) or a salt thereof as a solute is known.

[0003] These organic carboxylic acids can reduce the internal pressure of the electrolytic capacitor due to water vapor even in an environment exceeding 100 ° C. since the water content of the driving electrolyte can be reduced.

In addition, polyethylene glycol (Japanese Patent Publication No.
-76776), polyglycerin (JP-B-7-7)
No. 0443), a surfactant which improves the spark generation voltage and the chemical conversion property by adding an alkylene block polymer (Patent Registration No. 2732241) and the like are also known.

[0005]

However, in the conventional electrolytic solution for driving an electrolytic capacitor, the use environment at a high temperature and for a long time with the high-density mounting and the high ripple has recently been used as the use environment of the electrolytic capacitor in a device to be used. Under these circumstances, with conventional electrolytic solutions for driving electrolytic capacitors that use organic carboxylic acids and surfactants, although the degree varies depending on the type, the amount of water increases due to the esterification reaction with the solvent. The electrolytic capacitor is exposed for a long time under a high temperature environment due to an increase in moisture, and there is a problem that the deterioration of the cathode foil, especially without the chemical conversion coating, is accelerated. A section where excessive ripple load due to accelerated gas generation or a reduction in the combined capacity of the electrolytic capacitor causes problems such as valve operation. There is.

An object of the present invention is to solve such a conventional problem, and an object of the present invention is to provide an electrolytic solution for driving an electrolytic capacitor having a high temperature and a long life and an electrolytic capacitor using the same.

[0007]

In order to solve the above-mentioned problems, the present invention relates to a method of adding one or more solutes of an inorganic acid, an organic acid or a salt thereof to an organic solvent, and adding the solute to a cationic interface. This is a configuration in which an activator is added and dissolved.

According to the present invention, an electrolytic capacitor having stable characteristics for a long time even at a high temperature can be obtained.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, a solute of one or more of an inorganic acid, an organic acid or a salt thereof is added to an organic solvent, and a cationic surfactant is added thereto. It is an electrolytic solution for driving an electrolytic capacitor with a composition in which an agent is added and dissolved.With this configuration, the cationic surfactant is easily adsorbed to the surface of the cathode foil of the electrolytic capacitor by electric influence. Since the surface is coated to protect the cathode foil from moisture, it has an effect that an electrolytic capacitor having stable characteristics even when exposed to a high temperature for a long time can be provided.

A second aspect of the present invention is the invention according to the first aspect, wherein the cationic surfactant has a structure represented by the following chemical formula (3). Has the same function as the function according to the invention of (1). Here, the addition of the cationic surfactant alone with C ₂ H ₄ —O is not desirable because the solubility in ethylene glycol decreases.

[0011]

Embedded image

According to a third aspect of the present invention, in the first aspect, the cationic surfactant has a structure represented by the following chemical formula (4). Has the same function as the function according to the invention of (1).

[0013]

Embedded image

(Hereinafter, CH ₂ —O is referred to as EO and C ₂ H ₄ —O is referred to as PO.) Here, the addition of the EO—PO copolymer refers to the electrolytic solution for driving the electrolytic capacitor in the block copolymer. Has a low surface tension, causing a problem in foaming properties when impregnating the electrolytic capacitor element. Therefore, it is desirable to use a random copolymer.

According to a fourth aspect of the present invention, there is provided an electrolytic capacitor using the electrolytic solution for driving an electrolytic capacitor according to any one of the first to third aspects. This has the effect of providing an electrolytic capacitor capable of exhibiting stable performance at high temperatures for a long time.

Hereinafter, an embodiment of the present invention will be described. First, the structure of the cationic surfactant used in the present embodiment is shown in (Table 1).

[0017]

[Table 1]

As shown in (Table 1), the cationic surfactant of the present invention can have various structures due to the addition of EO and EP-PO, and requires the shape and the viscosity of the liquid. It can be selected according to the characteristics. This has the advantage that it can be used for an electrolytic solution for driving an electrolytic capacitor in any voltage range and that the work can be simplified.

In general, an electrolytic capacitor is constructed as shown in FIG. 1, in which an anode foil 1 serving as an anode electrode made of aluminum and a cathode foil 2 also serving as a cathode electrode also made of aluminum are provided with a separator 3 interposed therebetween. The element is formed by winding up such that it faces each other with the interposition of the element. A lead 4 is connected to each of the anode foil 1 and the cathode foil 2 of this element. An element having such a configuration is impregnated with an electrolytic solution for driving an electrolytic capacitor (not shown), the element is sealed in a case (not shown) such as an aluminum case, and a sealing material such as rubber or phenol resin is used. (Not shown) to constitute an electrolytic capacitor.

Next, this embodiment will be specifically described. The composition and characteristics of the electrolytic solution for driving an electrolytic capacitor of each example of the present invention and a conventional example as a comparative example are shown in (Table 2). At this time, the water content in the electrolytic solution for driving the electrolytic capacitor is 2
%. However, in the boric acid examples and the conventional examples, the water content was adjusted to 25%.

[0021]

[Table 2]

As shown in (Table 2), in Examples of the present invention, since a cationic surfactant is used, the conductivity is slightly lowered, but the spark generation voltage can be improved.
Thereby, the effect of improving the short-circuit property is also recognized.

Next, 20 electrolytic capacitors each using the electrolytic solution for driving an electrolytic capacitor shown in Table 2 were prepared.
The results of the life test are shown in (Table 3). The electrolytic capacitors used here were rated at 200 V
The ripple load test was performed at a test temperature of 105 ° C.

[0024]

[Table 3]

As can be seen from Table 3, in the conventional example, about 40% of the valves were opened after 7000 hours of the 105 ° C. ripple load test. The characteristics of the electrolytic capacitor using are stable and no problems such as valve opening occur. This proved that the cationic surfactant of the present invention had a great effect on heat resistance.

Next, a similar study was carried out using an electrolytic solution for driving an electrolytic capacitor obtained by adding a known surfactant to the conventional example while changing the organic carboxylic acid. Table 4 shows a comparison between the electrolytic solution for driving an electrolytic capacitor using the cationic surfactant of the present invention and the conventional driving solution using a surfactant. At this time, the water content of the electrolytic solution for driving the electrolytic capacitor was adjusted to 2%.

[0027]

[Table 4]

As shown in Table 4, no significant difference was observed in the electrical characteristics between the electrolytic solution for driving an electrolytic capacitor of the present invention and the conventional electrolytic solution for driving an electrolytic capacitor.

Further, 20 electrolytic capacitors each using the electrolytic solution for driving these electrolytic capacitors were prototyped, and the results of their life tests are shown in Tables 5 and 6. In addition,
The rating of the electrolytic capacitors used here is 400
V330 μF, and the test temperature was 125 ° C. for the organic carboxylic acid system (Conventional Example 3, Examples 7, 8, and 9), and 95 ° C. for the boric acid system (Conventional Example 4, Examples 10, 11, and 12).
A DC load test was performed. In addition, in the case of the organic carboxylic acid type (Conventional Example 3, Examples 7, 8, and 9), in order to make the effect of water remarkable, the evaluation was performed by intentionally adding 5% water to the electrolytic solution for driving the electrolytic capacitor. Was.

[0030]

[Table 5]

[0031]

[Table 6]

As can be seen from Tables 5 and 6,
In the embodiment of the present invention, the electrical characteristics of the electrolytic solution for driving the electrolytic capacitor were equivalent to those of the conventional example. In the example, all the valves were opened, but in the example of the present invention, it is very stable, and it can be seen that there is a clear difference.

To make this effect clearer,
The electrolytic capacitors after the tests of Conventional Example 4 and Example 7 were disassembled and the capacity and appearance of the cathode foil were examined. The results are shown in (Table 7).

[0034]

[Table 7]

As is clear from the results shown in Table 7, the cathode foil after the test of Conventional Example 4 had a reduced initial capacity ratio of 1/2 or less, and the surface was discolored to black. In the cathode foil of Example 7, little change in capacity was observed, and no discoloration was found. This confirms that the cationic surfactant of the present invention has the property of being able to protect the cathode foil surface even in a high-temperature environment, and provides an electrolytic capacitor having long-term stability at high temperatures. Is what you can do.

Although not shown in the above embodiment, 1
Since the same cathode foil as that used in the embodiment is used in the electrolytic capacitor of 00V or less, the same effect can be expected in the electrolytic solution for driving the electrolytic capacitor for low pressure.

The molecular weight of the cationic surfactant is determined by the polymerized portion of EO or EO-PO. It is preferably 20,000 or less in view of workability, but the purpose is to protect the cathode foil from moisture. In view of the above, the effect is remarkable at any molecular weight, and the range is not limited.

Further, the amount of the cationic surfactant to be added is specified as 0.01 wt% or more in the present invention, since the adsorption to the cathode foil can occur even in a very small amount.

[0039]

As described above, according to the present invention, one or more solutes of an inorganic acid, an organic acid, and a salt thereof are added to an organic solvent, and a cationic surfactant is added to the solute and dissolved. This constitutes the electrolytic solution for driving the electrolytic capacitor, which is used to compose the electrolytic capacitor.Since the surface of the cathode foil without the chemical conversion coating can be protected from moisture and high temperature environment, the characteristics are stable. It can contribute to the supply of electrolytic capacitors, and is of great industrial value.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a main part of an electrolytic capacitor according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode foil 2 Cathode foil 3 Separator 4 Leader

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masakazu Tanahashi 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Toshiaki Shimizu 1006 Kadoma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. An electrolytic solution for driving an electrolytic capacitor obtained by adding one or more solutes of an inorganic acid, an organic acid or a salt thereof to an organic solvent, and adding and dissolving a cationic surfactant thereto. 2. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the cationic surfactant has a structure represented by the following chemical formula (1). Embedded image 3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the cationic surfactant has a structure represented by the following chemical formula (2). Embedded image 4. An electrolytic capacitor using the electrolytic solution for driving an electrolytic capacitor according to claim 1.