JPH0963901A - Electrolyte of electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve electrolyte used for an electrolytic capacitor in spark generating voltage without increasing it in resistivity. SOLUTION: One or more kinds of materials selected out of organic acid, organic salt, inorganic acid, and inorganic salt and one or more kinds of materials selected from polyvinyl alcohol, polyvinyl pyrrolidone, copolymer of polyvinyl acetate and polyvinyl alcohol or polyvinyl pyrrolidone, and block copolymer of polyvinyl alcohol and polyvinyl pyrrolidone are dissolved into solvent composed of polyhydric alcohol and monohydric alcohol possessed of double bond C=C in its main chain.

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]

2. Description of the Related Art In recent years, there has been an increasing demand for the safety of electrolytic capacitors. Therefore, it is necessary to improve the withstand voltage of the electrolytic capacitor. The withstand voltage of the electrolytic capacitor is greatly affected by the withstand voltage of the dielectric oxide film of the anode, the properties of the electrolytic paper used as the separator, structural factors, and the properties of the electrolytic solution. That is, in order to improve the withstand voltage of the electrolytic capacitor, it is effective to increase the spark generation voltage of the electrolytic solution. In order to increase the spark generation voltage, a substance having a large molecular weight or a substance having a high viscosity is generally added to the electrolytic solution. For example, a medium- and high-voltage electrolytic solution has conventionally used a long-chain organic acid as a solute or added a polymer compound such as polyethylene glycol to increase the spark generation voltage.

[0003]

However, in general, when a substance having a large molecular weight or a substance having a high viscosity is added, the specific resistance of the electrolytic solution remarkably increases. Therefore, there is a demand for an electrolytic solution capable of improving the spark generation voltage while suppressing an increase in the specific resistance as low as possible. However, particularly in the case of electrolytes for high pressure, few effective means have been found.

An object of the present invention is to provide an electrolytic solution for an electrolytic capacitor which can prevent an increase in specific resistance and can improve a spark generation voltage.

[0005]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides an organic solvent in a polyhydric alcohol in which a monohydric alcohol having a C = C double bond in the main chain is dissolved. Acid, an organic acid salt, one or more of an inorganic acid or an inorganic acid salt, polyvinyl alcohol, polyvinylpyrrolidone, the polyvinyl alcohol or a copolymer of the polyvinylpyrrolidone and polyvinyl acetate, or a block copolymer of the polyvinyl alcohol and the polyvinylpyrrolidone. It is intended to provide an electrolytic solution for an electrolytic capacitor in which one or more polymers are dissolved.

As polyhydric alcohols, ethylene glycol, diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, etc. are used.

Monohydric alcohols having a C = C double bond in the main chain are 1-buten-3-ol and 1-hexene-
3-ol, linalool, geraniol, 3-methyl-
3-butene-1-ol or the like is used. The amount of dissolution of these substances is preferably 0.5 wt% or more, and if it is less than 0.5 wt%, the effect of increasing the spark generation voltage is reduced. Further, the upper limit of the amount of dissolution is such that each substance can be dissolved in the polyhydric alcohol.

As the organic acid, sebacic acid, 1,6-decanedicarboxylic acid, caprylic acid or the like is used. Organic acid salts are these salts, namely ammonium sebacate and 1,6-
Ammonium decanedicarboxylate, ammonium caprylate, etc. are used. Boric acid or the like is used as the inorganic acid. Ammonium borate or the like is used as the inorganic acid salt.

Further, polyvinyl alcohol (hereinafter referred to as PVA
And polyvinylpyrrolidone (hereinafter referred to as PVP), PVA and PVP and polyvinyl acetate (hereinafter referred to as PV)
It is preferable that the amount of dissolution of the copolymer with (expressed as Ac) or the block copolymer of PVP and PVP is in the range of 0.1 to 10 wt%. That is, when the dissolved amount is less than 0.1 wt%, the effect of improving the spark generation voltage becomes low. And the dissolution amount is 10
If it exceeds wt%, the viscosity remarkably increases and the impregnating property decreases. The solubility of PVA and PVP is higher than that of PVA and PVP.
The copolymer with VAc is superior.

[0010]

In general, the spark generation voltage tends to be higher in a compound having a larger molecular volume. When the shapes and sizes of molecules are similar, the values are close regardless of the presence or absence of double bonds. Alcohols may form an ester with an inorganic acid such as an organic acid or boric acid which is the main solute in the electrolytic solution, and even if the molecular volume of itself is not so large, the molecular volume is changed by esterification. Increase the spark generation voltage.
When a monohydric alcohol having a double bond in the main chain is used, the rotation of the molecule is regulated, so that the movement of ions as the main electrolyte is reduced. Therefore, the specific resistance of the electrolytic solution does not become so large.

PVA and PVP are water-soluble polymer compounds, and when dissolved in a polyhydric alcohol solvent, the spark generation voltage increases. Moreover, unlike other compounds having a large molecular weight, the molecular arrangement does not hinder the movement of ions in the liquid, so that the specific resistance does not increase. Furthermore, PVA and the copolymer of PVP and PVAc also have the effect of increasing the spark generation voltage and not increasing the specific resistance, like PVA and the like.

By using PVA or the like, a copolymer with PVAc, or a block copolymer of PVA and PVP together with a monohydric alcohol having a double bond in the main chain,
The spark generation voltage can be made higher than in the case of using alone.

[0013]

EXAMPLES The present invention will be described below based on examples.
Ethylene glycol, glycerin, or 1,4-butanediol is used as the polyhydric alcohol. A monohydric alcohol having a C = C double bond in the main chain is 1-butene-3.
-Ol, 1-hexen-3-ol, linalool, geraniol and 3-methyl-3-buten-1-ol are used. Then, this monohydric alcohol is dissolved in ethylene glycol or the like to obtain a solvent.

As the organic acid, ammonium sebacate, ammonium 1,6-decanedicarboxylate or ammonium caprylate is used. Boric acid or the like is used as the inorganic acid. Ammonium borate is used as the inorganic acid salt. These substances are dissolved in the above solvents.

Further, PVA, PVP, copolymers PVA-PVAc, PVP-PVAc, PVA and PVP
The block copolymer PVA-PVP of 1 is dissolved in the liquid as an additive.

Next, the specific resistance and the spark generation voltage of the electrolytic solutions of Examples having the compositions shown in Tables 1 and 2 and the conventional electrolytic solutions having the compositions shown in Table 2 were measured.

[0017]

[Table 1]

[0018]

[Table 2]

As is clear from Table 1 and Table 2, Example 1
Example 16 has a specific resistance of 700 to 2040 Ω · cm and a spark generation voltage of 480 to 510V. Further, as is clear from Table 2, in Conventional Example 1 to Conventional Example 5, the specific resistance was 105.
0 ~ 3570Ω ・ cm, spark generation voltage 450 ~ 470V
Becomes That is, Examples 1 to 16 are the same as the conventional example 1
-Compared with the conventional example 5, the specific resistance is low as a whole, and the spark generation voltage is about 1.02 to 1.13 times higher.

Further, with respect to each of the electrolytic solutions of Examples 1 and 2 described above, the amounts of PVA and PVP dissolved were changed,
The spark generation voltage was measured and the result is shown in FIG. FIG.
As is clear from the figure, the spark generation voltage rises sharply when the amount of PVA or PVP added is 0.1 wt% or more,
When it exceeds%, the value is almost constant. Therefore, the addition amount of PVA or the like is preferably in the range of 0.1 to 10 wt%.

[0021]

As described above, according to the present invention, a monohydric alcohol having a double bond in the main chain is used as a solvent to dissolve an organic acid or a salt thereof, an inorganic acid or a salt thereof, and , PVA and PVP, copolymers of these compounds and PVAc, and block copolymers of PVA and PVP are dissolved, so that an electrolytic solution for an electrolytic capacitor capable of increasing spark generation voltage without increasing specific resistance. Is obtained.

[Brief description of drawings]

FIG. 1 is a graph showing a spark generation voltage when the amounts of polyvinyl alcohol and polyvinylpyrrolidone added were changed in Examples of the present invention.

Claims (1)

[Claims] 1. A solvent prepared by dissolving a monohydric alcohol having a C = C double bond in its main chain in a polyhydric alcohol, and one or more of an organic acid, an organic acid salt, an inorganic acid or an inorganic acid salt. ,
An electrolytic solution for an electrolytic capacitor in which polyvinyl alcohol, polyvinylpyrrolidone, the polyvinyl alcohol, a copolymer of the polyvinylpyrrolidone and polyvinyl acetate, or one or more of the polyvinyl alcohol and the polyvinylpyrrolidone block copolymer are dissolved.