Compositions – Electrolytes for electrical devices
Reexamination Certificate
1999-10-29
2001-07-10
Koslow, C. Melissa (Department: 1755)
Compositions
Electrolytes for electrical devices
C361S504000, C361S505000, C361S506000
Reexamination Certificate
active
06258288
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mixture of long chain dibasic acids, a composition for an electrolytic solution for electrolytic capacitors using thereof, and the electrolytic solution for electrolytic capacitors.
2. Description of the Related Art
As a conventional electrolytic solution for electrolytic capacitors, especially as a middle and high voltage electrolytic solution for electrolytic capacitors, a solution containing ethylene glycol as a solvent and boric acid or its ammonium salt as a electrolyte is used. However, this type of electrolytic solution has problems in that the water content becomes high; that is, water is easily eliminated from the boric acid to form metaboric acid, and furthermore, water is formed from the esterification reaction between the boric acid and ethylene glycol. Thus, the water content of the electrolytic solution becomes high. As a result, when the electrolytic solution is used at a temperature over 100° C., the water in the electrolytic solution is vaporized, thereby causing an increase in the inner pressure of the electrolytic capacitor which destroys the capacitor.
In order to remedy the aforementioned problems, electrolytic solutions containing saturated linear dicarboxylic acids such as azelaic acid, sebacic acid, dodecanedioic acid or the salts thereof as a electrolyte have been used. However, since the solubility of the saturated linear dicarboxylic acid to a solvent, such as ethylene glycol, is low, the saturated linear dicarboxylic acid has a tendency to be crystallized at low-temperatures. By the crystallization, excess electric current may be caused, thereby deteriorating the low-temperature characteristics. Thus, the above mentioned problems are not solved yet.
Moreover, experiments using a dibasic acid as an electrolyte have been performed. As the dibasic acid, 2-butyloctanedioic acid (Japanese laid-open patent publication No. 60-13293), 8-vinyl-10-octadecenedioic acid (Japanese laid-open patent publication No. 4-186713) and 2-methylnonanedioic acid (Japanese laid-open patent publication No. 2-224217) or salts thereof are disclosed. These dibasic acids or salts thereof are useful since the solubility of these dibasic acids or salts thereof to a solvent, such as ethylene glycol, is improved compared to the aforementioned saturated linear dibasic acids or salts thereof.
Among the dibasic acids, 2-methylnonanedioic acid is a useful long chain dibasic acid. This dibasic acid can be produced by dicarboxylation of 1,7-octadiene in the presence of a palladium-phosphine catalyst (U.S. Pat. No. 4,629,807). However, according to this method, this dibasic acid can be obtained in a yield of only 19.1%. Therefore, by this method, an electrolytic solution having the desired ability cannot be produced.
Moreover, even if 2-methylnonanedioic acid could be fully supplied, the low-temperature characteristics may not be improved because the problems of the crystallization of the electrolyte at low temperatures are not yet solved. Therefore, improvement on the low temperature characteristics is desired.
Therefore, an electrolytic solution for electrolytic capacitors which comprises a long chain dibasic acid having an alkyl group at its side chain (e.g., 2-methylnonanedioic acid) as a main electrolyte but which does not cause any crystallization of the electrolyte is desired.
In view of the above, the present inventors have conducted extensive studies on the improvement of the low-temperature characteristics of the electrolytic solution using 2-methylnonanedioic acid. As a result, the present inventors have found that when one or more long chain dibasic acid having a carbon chain of 8 or more carbon atoms between both its carboxyl groups and having at its side chain an alkyl group and one or more alkoxycarbonyl group is mixed with 2-methylnonanedioic acid, the mixture can be a desirable electrolytic solution for electrolytic capacitors in that crystallization of the electrolyte hardly occurs at low temperatures; electrical conductivity is not reduced even at high temperatures; and high-voltage resistance can be improved. Thus, the present inventors accomplished the present invention.
SUMMARY OF THE INVENTION
The present invention relates to a mixture of long chain dibasic acids comprising one or more long chain dibasic acid (a first dibasic acid) having an alkyl group at its side chain and one or more long chain dibasic acid (a second dibasic acid) having a carbon chain of 8 or more carbon atoms between both its carboxyl groups and having at its side chain an alkyl group and one or more alkoxycarbonyl group.
In a preferred embodiment, the mixture of long chain dibasic acids comprises one or more long chain dibasic acid that contains 2 or more alkoxycarbonyl groups.
In a preferred embodiment, the alkoxycarbonyl group is a methoxycarbonyl group.
In a preferred embodiment, the mixture contains 2-methylnonanedioic acid, 2,4-dimethyl-4-methoxycarbonylundecanedioic acid, 2,4,6-trimethyl-4,6-dimethoxycarbonyltridecanedioic acid and 8,9-dimethyl-8,9-dimethoxycarbonylhexadecanedioic acid.
In a more preferred embodiment, 2-methylnonanedioic acid, 2,4-dimethyl-4-methoxycarbonylundecanedioic acid, 2,4,6-trimethyl-4,6-dimethoxycarbonyltridecanedioic acid and 8,9-dimethyl-8,9-dimethoxycarbonylhexadecanedioic acid are contained in the mixture at a ratio of 30 to 60:8 to 20:8 to 20:15 to 30 based on weight based on the total weight of the dibasic acids.
In a preferred embodiment, the mixture of long chain dibasic acids is obtained by the following method comprising the steps of:
(1)reacting hydrogen peroxide with cyclohexanone in methanol in the presence of an acid catalyst;
(2)reacting methyl methacrylate with the product of step (1) in the presence of metal salt; and
(3)hydrolyzing the reaction product of the step (2).
The present invention also relates to a composition for an electrolytic solution comprising a mixture of long chain dibasic acids and/or salts thereof of any one of the above long chain dibasic acids.
In a preferred embodiment, the salt is an ammonium salt.
In a more preferred embodiment, the long chain dibasic acid and/or ammonium salt thereof is dissolved in ethylene glycol.
The present invention also relates to an electrolytic solution for electrolytic capacitors which comprises a mixture of long chain dibasic acids and/or salt thereof.
In a preferred embodiment, the salt is an ammonium salt.
In a preferred embodiment, the dibasic acid and/or ammonium salt thereof is dissolved in ethylene glycol.
Further, the present invention relates to a method for producing a mixture of long chain dibasic acids, wherein the mixture comprises one or more long chain dibasic acid (a first dibasic acid) having an alkyl group at its side chain and one or more dibasic acid (a second dibasic acid) having a carbon chain of 8 or more carbon atoms between both its carboxyl groups and having at its side chain an alkyl group and one or more alkoxycarbonyl group, and wherein the method comprises the following steps of:
(1) synthesizing a mixture of long chain dibasic acid-esters by reacting an alkyl-substituted cycloalkanone and an alkyl methacrylate,
wherein the alkyl-substituted cycloalkanone has the following general formula I:
wherein n is an integer of 2 to 4, and R is H or a lower alkyl group having carbon number 1 to 4, wherein the alkyl group can be straight or branched; and
(2) obtaining a mixture of long chain dibasic acids by hydrolyzing the thus-obtained long chain dibasic acid-esters.
Moreover, the present invention relates to a method for producing a composition for an electrolytic solution, wherein the composition comprises one or more long chain dibasic acid and/or ammonium salt thereof having an alkyl group at its side chain and one or more long chain dibasic acid (a first dibasic acid) and/or ammonium salt thereof having a carbon chain of 8 or more carbon atoms between both its carboxyl groups and having at its side chain an alkyl group and one or more alkoxycarbonyl group, and wherein the method
Miyoshi Noritaka
Takii Kazuhisa
Uehata Masashi
Amin & Turocy LLP
Koslow C. Melissa
Okamura Oil Mills, Ltd.
LandOfFree
Composition comprising long chain dibasic acids and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composition comprising long chain dibasic acids and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composition comprising long chain dibasic acids and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2515262