JPS6314861B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrolytic solution for driving electrolytic capacitors, and its purpose is to provide an electrolytic solution that can be used particularly in medium-high voltage electrolytic capacitors to reduce internal resistance and expand the operating temperature range. It is in. Conventionally, an electrolytic solution prepared by adding boric acid or a salt thereof to a solvent such as ethylene glycol has been generally used.
However, this type of electrolytic solution has the disadvantage that it has a high specific resistance, increases capacitor loss, causes heat generation, and accelerates thermal deterioration. In order to improve these drawbacks, an electrolytic solution containing a linear saturated dicarboxylic acid such as azelaic acid, sebacic acid, decanedicarboxylic acid, or a salt thereof as a solute is sometimes used; Since the dicarboxylic acid has low solubility in solvents such as ethylene glycol, the dicarboxylic acid tends to precipitate as crystals at low temperatures, which inevitably leads to the deterioration of the low-temperature characteristics of the capacitor. Furthermore, in order to eliminate the drawbacks of the above-mentioned linear saturated dicarboxylic acids, some attempts have been made to use saturated dibasic acids or their salts having butyloctanedioic acid, 1,6-decanedicarboxylic acid side chains as solutes. ing.
However, although the solubility of these dicarboxylic acids or their salts in solvents such as ethylene glycol is improved compared to that of the linear saturated dicarboxylic acids or their salts, the properties at low temperatures are still insufficient and The current situation is that further improvements are desired. In view of the current situation, the present invention was developed as a result of intensive research to develop an electrolytic solution for driving electrolytic capacitors that does not have the above-mentioned drawbacks. The present inventors have discovered that when used as an electrolytic solution, it is difficult to precipitate as crystals even at low temperatures and can be used as a desired electrolytic solution for driving electrolytic capacitors, thereby completing the present invention. That is, the present invention provides a liquid polybasic acid or a salt thereof obtained by removing a high melting point substance having a melting point of about 90°C or higher from a polybasic acid mixture according to any one of the following (A), (B), and (C), by adding ethylene glycol to the liquid polybasic acid or its salt. The present invention relates to an electrolytic solution for driving an electrolytic capacitor, which is characterized by being dissolved in a solvent serving as a main solvent. (A) Polybasic acid mixture obtained by dimerizing peroxides of at least two cyclic ketones selected from cyclopentanone, cyclohexanone, and cycloheptanone (B) Butadiene, isoprene, acrylic acid, or ester thereof , at least one cyclic ketone selected from cyclopentanone, cyclohexanone, and cycloheptanone in the presence of at least one unsaturated compound selected from methacrylic acid or its ester, and maleic acid or its ester. Polybasic acid mixture obtained by dimerizing peroxide and/or saturated polybasic acid mixture obtained by hydrogenating the mixture (C) From the polybasic acid mixture obtained in (A) or (B) above Polybasic acid mixture formed by mixing two or more types of separated polybasic acids The electrolytic solution for driving an electrolytic capacitor of the present invention has a low resistivity, does not precipitate crystals even at low temperatures, and can be used at medium to high pressures. It can be suitably used as an electrolyte for electrolytic capacitors. First, the polybasic acid mixture used in the present invention [(A) ~
(C)] will be explained below. Regarding (A) As the cyclic ketone used as a starting material, at least two types selected from cyclopentanone, cyclohexanone, and cycloheptanone are used. In producing a cyclic ketone peroxide from a cyclic ketone, a cyclic ketone and hydrogen peroxide may be reacted in water-lower alcohol in the presence of an acid catalyst. Examples of acid catalysts used in this reaction include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid.
These acids are usually per mole of cyclic ketone.
0.01 mole or more, preferably about 0.02 to 0.05 mole is used. Examples of lower alcohols include methanol, ethanol, isopropanol, n-butanol, and tert-butanol. In this reaction, the lower alcohol is the cyclic ketone 1
It is usually advisable to use about 3 to 4 moles per mole.
Hydrogen peroxide is usually used in an amount of about 1 mole of cyclic ketone.
The amount of water used is preferably 0.5 to 1.5 mol, preferably about 0.7 to 1.2 mol, and the amount of water used is usually 2 mol or more, preferably 10 to 16 mol. When water is used, it can be mixed with hydrogen peroxide or lower alcohol beforehand. For example, it is used as a 30-35% hydrogen peroxide solution. In this reaction, the reaction is preferably carried out at 60 to 80°C, so that almost the entire amount of the cyclic ketone as a raw material is reacted to form a peroxide of the cyclic ketone. The peroxide thus produced is separately dried and used as a raw material for the next dimerization reaction. Moreover, since the peroxide is commercially available, a commercially available product can also be used as a raw material for the next dimerization reaction. The dimerization reaction is performed by dissolving or dispersing 1 mole of cyclic ketone peroxide in about 8 to 10 moles of an organic solvent, and then
Heat to 60-80°C in an autoclave and press a separately prepared ferrous salt solution. Examples of ferrous salts include ferrous chloride, ferrous sulfate, and ferrous acetate. As the organic solvent, lower alcohols such as n-butanol, isopropanol, ethanol, and methanol are preferable, and cyclic ketone peroxide 1
Preferably, 2 to 3 moles are used. The shorter the press injection is carried out, the better the yield will be, but there is a rapid generation of reaction heat, and in order to keep the reaction temperature constant, it is necessary to carry out the injection as quickly as possible within the cooling range. Next, the lower alkyl polybasic acid obtained above is
It is hydrolyzed to a polybasic acid according to conventional methods. This hydrolysis may use an acid or an alkali as a catalyst. For example, an alkali such as potassium hydroxide or sodium hydroxide is added to the above lower alkyl polybasic acid and water while heating and stirring, and after continued heating and stirring for several hours, a mineral acid such as sulfuric acid is added until the pH of the reaction solution is approximately 3. Just add it until it reaches the desired level. The polybasic acid thus produced can be easily isolated by extraction with an aromatic solvent such as benzene or toluene, washing with water, and then distilling off the solvent. The polybasic acid thus obtained is a mixture of various polybasic acids, and in the present invention, the mixture of polybasic acids is used as a mixture without being isolated into individual polybasic acids. Regarding (B) As the cyclic ketone used as a starting material, at least one selected from cyclopentanone, cyclohexanone, and cycloheptanone is used. In producing a cyclic ketone peroxide from a cyclic ketone, the reaction conditions in (A) above can be applied as is. Next, the cyclic ketone peroxide obtained above is dimerized in the presence of an unsaturated compound. As the unsaturated compound, at least one selected from butadiene, isoprene, acrylic acid or its ester, methacrylic acid or its ester, and malein or its ester is used. The amount of the unsaturated compound to be used is usually 0.1 to 0.5 mol, preferably 0.3 mol, per mol of the cyclic ketone peroxide. The dimerization reaction is preferably carried out by pouring and stirring a ferrous salt solution dispersed in a lower alcohol into the cyclic ketone and unsaturated compound solution, as in (A) above. Examples of the ferrous salts that can be used include ferrous sulfate, ferrous chloride, and ferrous acetate. When ferrous chloride is used as the ferrous salt,
Advantageously, after the reaction has ended, the oxidized iron compound can be reduced with hydrochloric acid and iron to regenerate ferrous chloride, which can therefore be recovered and reused. The amount of ferrous salt to be used is usually 1 to 2 mol, preferably 1.2 mol, per 1 mol of cyclic ketone peroxide.
The amount is preferably 1.5 mol. Examples of lower alcohols include methanol, ethanol, isopropanol, n-butanol, and tert-butanol. The reaction is usually 30 to 80
℃, preferably 60℃, generally 5 to 10℃.
The reaction completes in about minutes. In this way, a lower alkyl polybasic acid is produced. The lower alkyl polybasic acid produced above is then hydrolyzed to a polybasic acid according to a conventional method. The conditions for this hydrolysis may be the same as those in (A) above. Next, as a method for hydrogenating the polybasic acid obtained by the above hydrolysis, conventionally known methods can be widely applied, such as nickel catalyst (approximately 1.0 to 1.5% by weight).
The reaction may be carried out at 10 Kg/cm ² and 200° C. for 2 hours. The polybasic acid obtained above is a mixture of various polybasic acids, and in the present invention, such polybasic acids are used as a mixture. When dimerization is carried out in the presence of the above-mentioned unsaturated compound, a high molecular weight polymer may be mixed into the reaction product, but the proportion thereof is limited to about 0.5 to 1% of the total. Regarding (C), a wide range of conventional methods can be used to separate the polybasic acid mixture obtained in (A) or (B) above into individual polybasic acids, such as fractional distillation, solvent fractionation, etc. can be mentioned. The polybasic acids separated in this way are mixed in an arbitrary ratio. In the present invention, if a high melting point substance with a melting point of 90°C or higher is mixed in the polybasic acid mixture obtained in any of (A), (B) and (C) above, the high melting point substance is It is removed from the polybasic acid mixture by a conventional method such as a solvent crystallization method, converted into a salt form such as an ammonium salt if necessary, and then used as a solute in an electrolytic solution for driving an electrolytic capacitor. The ratio of the polybasic acid or its salt and ethylene glycol is not particularly limited and can be appropriately selected within a wide range, but the ratio of the former to the latter is usually 5 to 30:95 to 70 (W/W). It is best to use proportions. In the present invention, other solvents such as methyl cellosolve may be appropriately added to ethylene glycol as a solvent. Moreover, boric acid, adipic acid, etc. can also be appropriately added to the polybasic acid or its salt as a solute. Examples are given below to further clarify the present invention. Example 1 250 kg of hexane was placed in a high-pressure reaction vessel equipped with a stirrer,
After dissolving 11Kg of cyclohexanone peroxide, 9.3Kg of cyclopentanone peroxide, and 12.5Kg of cycloheptanone peroxide, 0.9Kg of concentrated sulfuric acid was gradually added while maintaining the liquid temperature at 50℃, and then the isoprene 8
Kg, butadiene 15Kg and methyl acrylate 4Kg
Add. 300Kg of anhydrous methanol in another reaction vessel
Add 100 kg of ferrous sulfate (heptahydrate) while blowing in nitrogen gas, stir thoroughly to create a suspension,
This is pressurized into the high pressure reaction vessel. While rapidly removing the reaction heat, the reaction temperature was maintained at 40°C, and the injection was completed in about 5 minutes. After stirring for an additional 15 minutes, the solvent and unreacted butadiene and isoprene were distilled off.
Obtain 210Kg of reaction solution. This is left to stand and separated into two layers, an upper polybasic acid layer and a lower iron salt liquid layer. The polybasic acid layer obtained from the upper layer contains some impurities such as unreacted methyl acrylate and caproic acid and enanthic acid, so it was stored under vacuum (25 mmHg).
The mixture was thoroughly degassed at 140°C, and some of the polybasic acids were produced as methyl esters, so they were hydrolyzed by a conventional method to obtain 51 kg of a clear light brown polybasic acid mixed solution. The acid value is 421, the iodine value is 118, and the unsaponifiable content is 0.52%. Furthermore, there were 26 peaks in total in the gas chromatography, indicating that the liquid was a mixture of various polybasic acids. Example 2 2 kg of methyl methacrylate and 1.5 kg of dimethyl maleate instead of acrylic acid in Example 1
The reaction was carried out in the same manner as in Example 1 except for adding
458, clear brown liquid with iodine value 102 and unsaponifiable matter 0.54%
55.5Kg was obtained. The peak by gas chromatography is 31. Example 3 The acid solution obtained in Example 2 was boiled under reflux with the same amount of methanol to reduce the oxidation level to 4.2, then the methanol was recovered and hydrogenated by a conventional method to determine the iodine value.
A 3.8 ester mixture was obtained. Vacuum 1
Distillation was carried out at mmHg of 150 to 240°C, and the initial distillate and final distillate were cut to obtain a middle distillate of approximately 35%. As a result of hydrolysis, the acid solution obtained has an acid value of 398, an iodine value of 2.9, and an unsaponifiable matter of 0.21%.
The peaks determined by gas chromatography are main peak 4,
The small peak is about 11. The polybasic acid mixtures obtained in Examples 1, 2, and 3 were heated and dissolved at about 50°C in 3 times the amount of toluene, and then slowly cooled to -20°C for about 8 hours, and the precipitated crystals were centrifuged. Separate and distill off toluene. The removed crystals are approximately 1 to
It is within the range of 4.5%. The polybasic acid mixtures obtained in Examples 1, 2, and 3 from which crystals were removed are designated as Sample 1, Sample 2, and Sample 3, respectively. Table 1 shows the solubility of these samples in ethylene glycol at 20°C, 10°C and 0°C. Table 1 shows ammonium borate, ammonium sebacate, dodecane 2 for comparison.
The solubility of ammonium acid and ammonium butyloctanoate in ethylene glycol is also shown.

[Table] Next, the performance of Samples 1 to 3 above when used as solutes in electrolytic capacitor driving fluids will be investigated. That is, sample 1, sample 2, sample 3, sebacic acid or butyloctanoic acid (purity
Add 9.3g of 98%) and 0.7g of ammonia, and heat at 30°C.
Specific resistance (Ωcm) and spark generation voltage (V) at
The results were as shown in Table 2.

[Table] In addition, after adjusting the concentration of each solute in ethylene glycol to match the specific resistance at 30℃ for aluminum electrolytic capacitors of 350V and 200μF, the temperature characteristics of loss were measured, and the results are shown in Table 3 below. Obtained.

【table】

【table】

Claims (1)

[Scope of Claims] 1. A liquid polybasic acid or its salt obtained by removing a high melting point substance with a melting point of about 90°C or higher from the polybasic acid mixture of any one of the following (A), (B) and (C), An electrolytic solution for driving an electrolytic capacitor, characterized in that it is dissolved in a solvent containing glycol as a main solvent, (A) a peroxide of at least two cyclic ketones selected from cyclopentanone, cyclohexanone, and cycloheptanone; (B) the presence of at least one unsaturated compound selected from butadiene, isoprene, acrylic acid or its ester, methacrylic acid or its ester, and maleic acid or its ester; Below, a polybasic acid mixture obtained by dimerizing at least one peroxide of a cyclic ketone selected from cyclopentanone, cyclohexanone, and cycloheptanone, and/or a polybasic acid mixture obtained by hydrogenating the mixture. Saturated polybasic acid mixture, (C) A polybasic acid mixture obtained by mixing two or more types of polybasic acids separated from the polybasic acid mixture obtained in (A) or (B) above.