JPS584917A - Electrolyte for driving aluminum electrolytic condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in electrolytes for driving aluminum electrolytic capacitors.

BACKGROUND ART Conventionally, a solution in which an ammonium salt of an organic carboxylic acid is dissolved in ethylene glycol as a main solvent is known as an electrolytic solution.

Such an electrolyte has excellent effects on the low-temperature characteristics of the capacitor, but on the other hand, it has the drawback of causing corrosion during a high-temperature load test of the capacitor.

That is, to explain the corrosion of r in the typical aluminum electrolytic capacitor shown in the figure, the capacitor has a wound element (l,
A case (2) that houses the element, a sealing plate (3) that seals the opening of the case and is made of a combination of a synthetic resin plate (4) and a rubber plate (5), an external terminal (6), and a sealing plate (3) that seals the opening of the case, an external terminal (6), and It consists of an internal terminal (8) that connects the lead foil (η),
During the high temperature load test, especially the 9-wire foil (7) and internal terminals (8)
) K corrosion is seen. Corrosion is accelerated by charging/discharging and flowing ripple current, and eventually lead foils (η, etc.) are corroded and cut.

Therefore, the object of the present invention is to provide an electrolytic solution that is a combination of ethylene glycol and an ammonium salt of an organic carboxylic acid.
An object of the present invention is to provide an improved electrolytic solution for driving an aluminum electrolytic capacitor that can prevent the above-mentioned corrosion without impairing its excellent properties.

That is, the electrolytic solution of the present invention is prepared by dissolving an ammonium salt of an organic carboxylic acid as an ionogen in ethylene glycol as a main solvent, and adding 0.5 to 10% of boron oxide (B!05) to the electrolytic solution.
It is characterized by the addition of % by weight, which makes it especially suitable for aluminum sealed with a sealing plate whose inner surface is made of polypropylene resin! the intended purpose can be effectively achieved.

In the electrolytic solution of the present invention, when the amount of boron oxide added is less than 0.5% by weight, almost no corrosion suppression or prevention effect is observed, whereas when it exceeds 10% by weight, the corrosion prevention effect is sufficient. As a side effect, the viscosity of the electrolytic solution increases and the conductivity decreases, which is undesirable because it causes a decrease in capacity and an increase in loss in the low humidity characteristics of the capacitor.

Therefore, these addition amount ranges are excluded from the present invention.

In the electrolytic solution of the present invention, ammonium salts of organic carboxylic acids such as adipic acid, speric acid, and sepatic acid are suitable.

Historically, in the electrolytic solution of the present invention, the content ratio of ethylene glycol as a solvent and the ammonium salt of an organic carboxylic acid as a solute is arbitrary, and the solute is usually used within the solubility limit.

Examples of the present invention will be described below.

In the examples of the present invention, boron oxide, which is an additive, dissolves well in a solvent at around 100°C.
The solute and additives were mixed to form an electrolyte, which was then used to form a capacitor of the form described and illustrated. The following tests were conducted with such a capacitor.

The capacitor rating is 140V and 680μF, and the ripple load test was conducted at a temperature of 85℃ and a ripple current of 60t.
Testing was conducted under the conditions of 2 people and a current application time of 500 hours.

Table 1 In Table 1, Z/Z □ is 120- at -25℃
It represents the ratio of the impedance (zO) at 120°C and the impedance (zO) at 1,200°C, and the smaller this value is, the better the low-temperature performance is. Synthetic resin plate (4) constituting the sealing plate (3) of
) (see drawing) is made of phenolic resin 6 As is clear from Table 1, when boron oxide is added to a basic electrolyte consisting of ethylene glycol and an ammonium salt of an organic carboxylic acid, the basic electrolyte has excellent low-temperature properties. Effective corrosion prevention can be achieved with almost no damage to the surface.

It should be noted that polypropylene resin is more susceptible to corrosion by electrolyte than phenol resin, so even when the synthetic resin plate (4) is made of polypropylene resin, it is naturally possible to obtain an effective corrosion prevention effect.

The effect of adding boron oxide depends on the amount added. Table 2 shows the additive amount effect as a typical example when ethylene glycol and ammonium adipate are selected as the basic electrolyte.

Margin Table 2 In Table 2 below, 2μG has the same meaning as in Table 1, and M and B respectively constitute the inner surface of the sealing plate (3) of the capacitor subjected to the test in Table 2. The synthetic resin plate (4)
This includes cases where it is made of a small amount of resin and cases where it is made of polypropylene resin.

As is clear from Table 2, when the synthetic resin plate (4) is made of polypropylene, it is effective to add boron oxide in an amount of 0.5 to 10 by weight.

Furthermore, in the present invention, it has been confirmed that even if a hydrogen absorbent is further added to prevent an increase in the internal pressure of the capacitor due to the generation of hydrogen gas, the respective effects of the hydrogen absorbent and boron oxide are effectively produced. . For example, ethylene glycol 1o o
When the same type of test as shown in Table 1 was carried out using an electrolytic solution prepared by adding 2% by weight of boron oxide and 0.5P of dinitrophenol as a hydrogen absorbent to a basic electrolytic solution consisting of cc, ammonium adipate 5P, 2β0 was 1.16, no corrosion occurred, and no increase in the internal pressure of the capacitor was observed.

As is clear from the above description, according to the present invention, boron oxide is added to an electrolytic solution in which an ammonium salt of an organic carboxylic acid as an ionogen is dissolved in ethyne glycol as a main solvent, and the sealing plate is sealed with a polypropylene resin inner surface. Corrosion within the capacitor is prevented and a highly reliable aluminum electrolytic capacitor can be obtained.

[Brief explanation of drawings]

The figure shows a typical aluminum electrolytic capacitor. 1 shows a cross-sectional view of the sensor, in which (1) is a winding element, (2) is a case, and (3) is a sealing plate. 63-

Claims (1)

[Claims] (1) An electrolytic solution for aluminum electrolytic capacitors sealed with a sealing plate with a polypropylene resin inner surface, which is oxidized into an electrolytic solution in which ammonium salts of speric acid, adipic acid, or sepatic acid are dissolved as ionogen in ethylene glycol as the main solvent. An electrolytic solution for driving an aluminum electrolytic capacitor, characterized in that boron is added in a proportion of 0.5 to 10% by weight.