JPH04286109A - Electrolytic solution for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To provide a dielectric solution for a dielectric capacitor capable of embodying flameproofing, reducing specific resistance without deteriorating an anode oxide film and increasing spark voltage. CONSTITUTION:In terms of a electrolytic capacitor's dielectric solution made of an organic solvent, such as ethylene glycol, inorganic oxides, such as boric acid or ammonia borate and silicon, boron, titanium, vanadium, zirconium, zinc, and magnsium, are added to manufacture a dielectric capacitor's electrolytic solution. Since the inorganic oxides, such a boric acid are added, flameproofing is available. Moreover, such substances as boric acid or phosphoric acid can be reduced, this construction makes it possible to inhibit the deterioration of an anode oxide film, and reduce specific resistance and moreover inhibit a drop in spark voltage.

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 electrolytic capacitors.

0002

[Prior Art] Electrolytes for electrolytic capacitors are generally
The main solvent is an organic substance such as ethylene glycol, which makes it flammable.

[0003] In recent years, there has been an increasing demand for safety in equipment, and the electrolytic capacitors incorporated therein have also become required to be flame-retardant and will not burn even if destroyed.

[0004] In order to make electrolytic capacitors flame retardant, conventionally, boric acid or ammonium borate has been used as a solute, or a component prepared by dissolving a phosphate ester has been used as an electrolytic solution.

[0005]

[Problems to be Solved by the Invention] However, although an electrolytic solution containing ethylene glycol and boric acid exhibits self-extinguishing properties, due to the high concentration of boric acid, an esterification reaction occurs and a large amount of water is produced. This causes significant deterioration of the anodic oxide film and also has the disadvantage of relatively high specific resistance. In order to improve these drawbacks, there are electrolytes that use organic acid ammonium salts as solutes and add phosphorus-based flame retardants, but they have the drawback that the spark voltage decreases when large amounts of phosphorus-based flame retardants are added. .

The purpose of the present invention is to improve the above-mentioned drawbacks and to reduce the specific resistance without deteriorating the anodic oxide film.
The present invention provides an electrolytic solution for electrolytic capacitors that can improve flame retardancy and spark voltage.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention involves adding boric acid or a salt thereof and an inorganic oxide to an organic solvent-based electrolytic solution for electrolytic capacitors. The present invention provides an electrolytic solution for electrolytic capacitors having characteristics.

[0008]

[Action] Boric acid and ammonium borate promote carbonization of the electrolytic solution and electrolytic paper and have a self-extinguishing effect. Also,
Inorganic oxides are thought to form a protective film on the surface of burning substances, blocking the intrusion of thermal energy and oxygen, and thus preventing combustion.

[0009] Boric acid and the like are also a cause of water generation, and since this amount can be reduced, deterioration of the anodic oxide film can be suppressed and specific resistance can also be reduced.

Furthermore, since the amount of phosphorus-based flame retardants can be reduced, a drop in spark voltage can also be suppressed.

[0011]

EXAMPLES The present invention will be explained below based on examples. An organic solvent such as ethylene glycol is used as the solvent. Ammonium 1,6-decanedicarboxylate, ammonium azelaate, ammonium sebacate, ammonium benzoate, etc. are used as the solute. Boric acid or ammonium borate is added in an amount of 3 to 10 wt%. Silicon, boron, titanium, vanadium, zirconium, zinc, magnesium, etc. are used as the inorganic oxide, and preferably the particle size is 0.
The thickness is 1 μm or less, and the amount added is 1 to 10 wt%.

Next, regarding the electrolytic solution having the composition shown in Table 1,
Specific resistance and spark voltage were measured. The specific resistance is the value at a temperature of 30°C, and the spark voltage is the value at 85°C.

[0013]

[Table 1]

As is clear from Table 1, Examples 1 to 12 have specific resistances of 350 to 700 Ω·cm and spark voltages of 360 to 500V. In addition, in conventional examples 1 to 6, the specific resistance is 340 to 1,600 Ω・cm, and the spark voltage is 2.
It becomes 00-450V. Comparing the two, the former has a maximum resistivity that is 7/16 lower. The spark voltage in the former case is 1.8 times the minimum value and 1.1 times the maximum value.
It's more than twice as expensive.

Further, flame retardance was measured using an aluminum electrolytic capacitor element with a diameter of 35 mm and a length of 40 mm impregnated with an electrolytic solution having the composition shown in Table 1. As shown in Fig. 1, the measurement method is to hold the capacitor element 1 on a fixed stand 2, tilt it at 45 degrees to the perpendicular, and place it 15 m from the tip 4 of the gas burner 3.
Place it above m. In this state, the process of applying a flame to the capacitor element 1 for 5 seconds and releasing it for 3 seconds is repeated 10 times. The whole is surrounded by hood 5. If the capacitor element 1 burned during this operation, it was removed from the flame and the time until the fire was extinguished was measured.

The measurement results show that in Examples 1 to 12, the capacitor element 1 does not burn even if the operation of exposing it to the flame is repeated 10 times. On the other hand, Conventional Examples 1 to 3 and Conventional Example 6 burned after being exposed to the flame only once, and did not extinguish the flame. Furthermore, although Conventional Example 4 does not burn even after 10 repetitions, its specific resistance is extremely high. Furthermore, Conventional Example 5 burned for the fourth time and took 3 seconds to extinguish.

[0017]

As described above, according to the present invention, by adding boric acid or the like and an inorganic oxide, an electrolytic solution for an electrolytic capacitor that can be made flame retardant can be obtained. In addition, since the amount of added boric acid etc. can be reduced, deterioration of the anodic oxide film can be suppressed and specific resistance can be lowered, and the amount of phosphoric acid-based flame retardants can also be reduced, preventing a drop in spark voltage for electrolytic capacitors. An electrolyte is obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for conducting a combustion test of a capacitor element.

[Explanation of symbols]

1... Capacitor element, 3... Gas burner.

Claims (1)

[Claims] 1. An electrolytic solution for an electrolytic capacitor, which is an organic solvent-based electrolytic solution, characterized in that boric acid or a salt thereof and an inorganic oxide are added.