JPH04284614A - Electrolyte for electrolytic capacitor - Google Patents

Abstract

PURPOSE:To provide an electrolyte, for electrolytic capacitor, which can reduce a resistivity, which can make a sparking voltage high and which can be made noncombustible without deteriorating an anodized film. CONSTITUTION:At an electrolyte, for electrolytic capacitor use, which is based on an organic solvent such as ethylene glycol or the like, the electrolyte for electrolytic capacitor use is featured in such a way that a saccaride such as sorbitol, starch, dextrin, fructose, glycose, arabinose, ribose, xylose, erythritol or the like and boron oxide are added. When the saccharide and the boron oxide are added, a carbide is produced at a burning operation and disturbs its progress. Since boric acid and a phosphoric acid-based flame retardant can be reduced, it is possible to restrain an anodized film from being deteriorated, to lower a resistivity and to restrain a sparking voltage from being lowered.

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 in which ethylene glycol and boric acid, etc. are dissolved, exhibits self-extinguishing properties, it is necessary to increase the concentration of boric acid, which causes an esterification reaction and causes water to evaporate. The anodic oxide film is produced in large amounts, resulting in significant deterioration of the anodic oxide film, and the specific resistance is also relatively large. These drawbacks can be improved by using an organic acid ammonium salt as a solute and adding a flame retardant such as a phosphoric acid ester, but if a large amount of phosphorus-based flame retardant is added, the spark voltage decreases.

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 provides an organic solvent-based electrolyte for an electrolytic capacitor in which sugars and boron oxide are added. It provides an electrolyte.

[0008]

[Action] When sugars such as sorbitol, starch, dextrin, fructose, glycose, arabinose, ribose, xylose, and erythritol, and boron oxide are added to an organic solvent-based electrolyte, when burned, the electrolyte and electrolytic paper produces a lot of char, which hinders the progress of combustion.

[0009] Boric acid and ammonium borate are a cause of water generation, but since the 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 phosphoric acid-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, etc. are used as the solute. Phosphoric acid or the like is used as an additive. As the saccharide, one or more of sorbitol, starch, dextrin, fructose, glycose, arabinose, ribose, xylose, and erythritol is used and dissolved at about 5 to 15 wt%. Further, boron oxide dissolves in an amount of about 2 to 5 wt%.

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

[0013]

[Table 1]

As shown in Table 1, Examples 1 to 10 have a specific resistance of 700 to 910 Ω·cm and a spark voltage of 420 Ω·cm.
~500V. Conventional Examples 1 to 5 have a specific resistance of 670 to 1,590 Ωcm and a spark voltage of 200Ω.cm.
~450V. Comparing the two, the maximum value of the resistivity of the former is about 43% lower than that of the latter. Also, regarding the spark voltage, the former has a minimum value of 2.
1 times higher, and the maximum value is more than 1.1 times higher.

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 10, 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 Example 1 does not burn even after 10 repetitions, but its specific resistance is extremely high. Also, conventional example 2
-Conventional Example 4 burned after being exposed to flame only once, and did not extinguish. Conventional Example 5 burned for the fourth time and took 3 seconds to extinguish.

[0017]

As described above, according to the present invention, since sugars and boron oxide are added, an electrolytic solution for electrolytic capacitors that can be flame-retardant can be obtained. In addition, since the amount of added boric acid and phosphoric acid flame retardants can be reduced, it is possible to suppress the deterioration of the anodic oxide film, lower the specific resistance, and obtain an electrolytic solution for electrolytic capacitors that can prevent a drop in spark voltage. .

[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 organic solvent-based electrolytic solution for an electrolytic capacitor, characterized in that a sugar and boron oxide are added thereto.