JP2010135703A - Electrolytic solution for driving electrolytic capacitor and electrolytic capacitor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic solution for driving an electrolytic capacitor excellent in tracking resistance, and to provide the electrolytic capacitor using the electrolytic solution. <P>SOLUTION: The electrolytic solution contains at least one solute selected from an organic acid or an organic acid salt and an inorganic acid and precursors of insulating resin in a solvent composed of an organic solvent as a body. As the insulating resin, at least one resin is selected from polyimide resin, phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane resin, etc., and especially an electrolytic solution which contains 4,4-diaminodiphenyl ether and 1,2,4,5-benzenetetracarboxylic anhydride which are precursors, and forms the polyimide resin is suitable for satisfying tracking resistance. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an improvement in an electrolytic solution for driving an electrolytic capacitor (hereinafter referred to as an electrolytic solution), which can improve the tracking resistance of the electrolytic solution and drive an electrolytic capacitor with high safety as a product. The present invention relates to an electrolytic solution for use.

  A capacitor is one of general electronic components, and is widely used in various electric and electronic products mainly for power supply circuits and noise filters for digital circuits.

  In general, an aluminum electrolytic capacitor is obtained by subjecting a high-purity aluminum foil to an electrochemical etching treatment to increase the surface area, and then performing a chemical conversion treatment in a chemical conversion solution such as an aqueous ammonium borate solution or an aqueous ammonium adipate solution. A capacitor element obtained by inserting and winding a separator between an anode foil having an oxide film formed on the surface and a cathode foil obtained by etching a high-purity aluminum foil is impregnated with an electrolytic solution, After being accommodated in the cylindrical case, the opening is sealed with elastic rubber, and the sealed portion is drawn.

  In recent years, safety of electrical appliances has been regarded as a problem, and the demand for safety regarding electrolytic capacitors has also increased, and an electrolytic solution used for electrolytic capacitors has been developed to improve safety.

  Conventional electrolytes have used ethylene glycol or γ-butyrolactone as a main solvent, and an ammonium salt such as adipic acid or benzoic acid dissolved therein as an electrolyte.

  In the electrolytic capacitor, in addition to improving the tracking resistance of the electrolytic solution in the name of improving safety, the electrolytic solution is improved by various methods. For example, there is a method of using an electrolyte solution in which an electrolyte solution is flame-retardant and silicon-containing polyvinyl alcohol and boric acid or a salt thereof are dissolved, or a capacitor element is a driving electrolyte solution containing an amine compound and a polyhydric alcohol solvent. The method of making the electrolyte solution flame-retardant by bringing into contact with the gel and suppressing a short circuit when a high voltage is applied is used. (For example, refer to Patent Documents 1 and 2).

7-19730 JP-A-5-175079

  However, when an overvoltage is applied to the electrolytic capacitor and the electrolyte discharged when the valve is actuated adheres to the substrate, even the flame-retardant electrolyte will cause the evaporation of the solvent, thereby concentrating the electrolyte. As it progresses and the withstand voltage decreases, there is a problem that a spark is generated due to tracking, which eventually leads to a short circuit on the board. Therefore, a highly safe electrolytic capacitor that does not cause a fire has been demanded.

  In view of the above problems, the present invention provides an electrolytic capacitor with improved safety by improving the electrolytic solution so that when an overvoltage is applied, the sprayed electrolytic solution does not cause a spark due to tracking on the substrate. It is intended to provide.

  The present invention has been discovered as a result of various studies in order to solve the above-described problems, and focuses on the characteristics of an insulating resin and intends to apply the characteristics to an electrolyte.

  The electrolytic solution for driving the electrolytic capacitor of the present invention comprises at least one solute selected from an organic acid, an organic acid salt, and an inorganic acid in a solvent mainly composed of an organic solvent, and a precursor of an insulating resin. It is characterized by including.

  The insulating resin is polyimide, and the precursor is 4,4′-diaminodiphenyl ether represented by the following formula and 1,2,4,5-benzenetetracarboxylic anhydride. With the electrolytic solution containing the precursor, life characteristics and tracking resistance can be improved.

  Further, as an insulating resin to replace polyimide resin formed by polymerization of 4,4'-diaminodiphenyl ether and 1,2,4,5-benzenetetracarboxylic anhydride, phenol resin, epoxy resin, melamine resin, urea resin , Unsaturated polyester resins, alkyd resins, and polyurethane resins. Examples of these precursors include the following.

Phenol resin precursors include phenol and formaldehyde.
Examples of the epoxy resin precursor include bisphenol A and epichlorohydrin.
Melamine and formaldehyde are mentioned as a melamine resin precursor.
The urea resin precursor includes urea and formaldehyde.
Examples of the unsaturated polyester resin precursor include terephthalic acid and ethylene glycol.
Examples of the alkyd resin precursor include fatty acids and glycerin.
Examples of the polyurethane resin precursor include diisocyanate hexane and ethylene glycol.

  The addition amount of the insulating resin precursor is preferably 0.5 to 20.0 wt%.

As the organic solvent, one or more solvents selected from a protic solvent and an aprotic solvent can be used.
Examples of the protonic solvent include methyl alcohol, ethyl alcohol, butyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin and the like, and among these, ethylene glycol is preferable. Examples of aprotic solvents include lactone compounds such as γ-butyrolactone.

In the electrolytic solution of the present invention, a solvent may be added in addition to the ethylene glycol.
Examples of the solvent species include one or more selected from the group consisting of alcohols, ethers, amides, oxazolidinones, lactones, nitriles, carbonates, and sulfones. Specific examples of the solvent are as follows, and two or more kinds can be used in combination.

  Examples of alcohols include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, diacetone alcohol, benzyl alcohol, amyl alcohol, furfuryl alcohol, ethylene glycol, propylene glycol, diethylene glycol, hexylene glycol, glycerin, and hexitol.

  As ethers, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol phenyl ether, tetrahydrofuran, 3-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl Examples include ether.

  In addition, examples of the high molecular weight material include polyalkylene glycols such as polyethylene glycol and polypropylene glycol and copolymers thereof (hereinafter referred to as polyalkylene glycol).

  As amides, N-methylformamide, N, N-dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N, N-diethyl Examples include acetamide and hexamethylphosphoric amide.

  Examples of oxazolidinones include N-methyl-2-oxazolidinone and 3,5-dimethyl-2-oxazolidinone.

  Examples of lactones include γ-butyrolactone, α-acetyl-γ-butyrolactone, β-butyrolactone, γ-valerolactone, and δ-valerolactone.

  Examples of nitriles include acetonitrile, acrylonitrile, adiponitrile, 3-methoxypropionitrile and the like.

  Examples of carbonates include ethylene carbonate and propylene carbonate.

  Examples of the sulfones include dimethyl sulfone, ethyl methyl sulfone, diethyl sulfone, sulfolane, 3-methyl sulfolane, and 2,4-dimethyl sulfolane.

  Examples of other solvents include water, N-methyl-2-pyrrolidone, dimethyl sulfoxide, 1,3-dimethyl-2-imidazolidinone, toluene, xylene, and paraffins.

  Of the solvents shown above, a particularly preferred one is ethylene glycol.

  As the electrolyte used in the present invention, one or more electrolytes selected from carboxylic acids and carboxylates can be used. Examples of acids include acetic acid, oxalic acid, propionic acid, benzoic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanoic acid, 2-methyl azelaic acid, 1,6- Examples include decanedicarboxylic acid, 5,6-decanedicarboxylic acid, 2-butyloctanedioic acid, 7-vinylhexaden-1,16-dicarboxylic acid, fumaric acid, maleic acid, phthalic acid, and ammonium and amine salts thereof. It is done.

Furthermore, various additives generally used as capacitor driving electrolytes can be added to the above electrolyte for the purpose of reducing leakage current, improving withstand voltage, gas absorption, and the like.
Examples of additives include sugars such as glucose, fructose, mannitol, xylose, galactose, polymer compounds such as polyvinyl alcohol, polyethylene glycol, polypropylene glycol, nitrophenol, nitrobenzoic acid, nitroacetophenone, nitroanisole, dinitrobenzoic acid And silane coupling agents such as colloidal silica.

When the electrolytic solution added with the insulating resin precursor used in the electrolytic solution of the present invention is jetted onto the substrate, the polymerization reaction proceeds by heat due to energization, etc., and by forming the insulating resin on the substrate, Tracking resistance can be improved.
In addition, since the above polymerization reaction occurs at 200 ° C. or higher in the absence of a catalyst, the polymerization reaction does not occur inside the capacitor even when the precursor of the insulating resin is added to the electrolytic solution, and the life of the product It does not deteriorate the characteristics.

  Examples of the present invention will be specifically described below. The following examples are for illustrating the present invention, and the present invention is not limited to the following contents.

A method for manufacturing a wound electrolytic capacitor used in the examples will be described below.
A high-purity aluminum foil is electrochemically etched to increase the surface area, then an aqueous solution of ammonium borate is used as a chemical conversion solution, and an anode foil having an oxide film formed on the surface of the etching foil is formed. A separator element was inserted between the pure aluminum foil and the cathode foil etched to produce a capacitor element.
And after impregnating the electrolytic solution shown in Table 1 into this capacitor element and storing it in a metal bottomed cylindrical case, the opening is sealed with elastic rubber, and the sealed portion is drawn and processed. A wound electrolytic capacitor of 200 WV-1500 μF (φ30 × 50 L) was produced.

  Table 1 shows the electrolyte composition used and the specific resistance at 30 ° C.

[Examples 1 to 9] Comparison of tracking characteristics depending on the composition of the precursors The electrolyte solution compositions of Examples 1 to 9 were water 1.0 wt%, ethylene glycol 42.0 to 85.4 wt%, and ammonium sebacate 10.0 wt%. , Boric acid 3.0 wt%, and 4,4′-diaminodiphenyl ether 0.3-22.0 wt%, 1,2,4,5-benzenetetracarboxylic anhydride as a precursor of polyimide as an insulating resin It was 0.3-22.0 wt%, and the tracking characteristic comparison by these compositions was performed.
Using the electrolytic solutions of Examples 1 to 9 described in Table 1, an electrolytic capacitor having the rated power of 200 WV-1500 μF (φ30 × 50 L) was prepared (n = 10 for each condition), attached to the substrate, and a voltage of 350 V, Energization was performed under the condition of current 2A, and the time (seconds) until the occurrence of spark by tracking was measured.
The results are shown in Table 1.

(Comparative Examples 1-3)
In Comparative Example 1, 4,4′-diaminodiphenyl ether and 1,2,4,5-benzenetetracarboxylic anhydride were not added. In Comparative Example 2, only 4,4′-diaminodiphenyl ether was 5.0 wt%. In Comparative Example 3, only 1,2,4,5-benzenetetracarboxylic acid anhydride was added in an amount of 5.0 wt%, and the amount of ethylene glycol was adjusted accordingly. In the same manner as described above, the tracking characteristics of these compositions were compared. The results are shown in Table 1.

  As shown in Table 1, Comparative Example 1 in which both 4,4′-diaminodiphenyl ether and 1,2,4,5-benzenetetracarboxylic anhydride were not added, only one of them was added, comparison In Examples 2 and 3, sparks due to tracking occurred in 10 seconds.

  On the other hand, Examples 1 to 9, in which 4,4′-diaminodiphenyl ether and 1,2,4,5-benzenetetracarboxylic anhydride according to the present invention were used in combination and added in an amount of 0.3 to 22.0 wt%, respectively, were compared. Compared to Examples 1 to 3, it has better tracking resistance. Among them, Examples 4 to 8 in which the amount of 4,4′-diaminodiphenyl ether and 1,2,4,5-benzenetetracarboxylic anhydride added are in the range of 0.5 to 20.0 wt%, Even after 20 minutes of the energizing condition, no spark is generated by tracking, an increase in specific resistance is suppressed, and further excellent characteristics are obtained.

  Next, the electrolytic capacitors according to Examples 1 to 9 and Comparative Examples 1 to 3 were subjected to a 105 ° C. rated application test, and the characteristics after 5000 hours were compared (n = 10 for each condition). The results are shown in Table 2.

As shown in Table 2, Examples 1 to 9 to which both 4,4′-diaminodiphenyl ether and 1,2,4,5-benzenetetracarboxylic acid anhydride were added were subjected to a 105 ° C. rated application test after 5000 hours. It can be seen that the life characteristics are equivalent to those of Comparative Examples 1 to 3, and are stable. Here, since the polymerization reaction for forming polyimide occurs at 200 ° C. or higher in the absence of a catalyst, it does not deteriorate the product life characteristics at 105 ° C. rated application.
As described above, according to the present invention, an electrolytic capacitor having high safety and stable life characteristics can be put into practical use.

In the above examples, the insulating resin is polyimide, and the precursor is 4,4′-diaminodiphenyl ether and 1,2,4,5-benzenetetracarboxylic anhydride. As a resin precursor,
Phenol resin precursor: phenol and formaldehyde,
Epoxy resin precursor: bisphenol A and epichlorohydrin,
Melamine resin precursor: melamine and formaldehyde,
Urea resin precursor: urea and formaldehyde,
Unsaturated polyester resin precursor: terephthalic acid and ethylene glycol,
Alkyd resin precursor: fatty acid and glycerin,
When the polyurethane resin precursor: diisocyanate hexane and ethylene glycol were used, the same effects as described above could be obtained.

And this invention is not limited to the said Example, The well-known additive used for the electrolyte solution which melt | dissolved the various solutes illustrated previously individually or in multiple, and the drive electrolyte solution of an electrolytic capacitor was added The same effect as in the above example could be obtained for the electrolytic solution.

Claims (4)

  An electrolytic solution for driving an electrolytic capacitor, comprising a precursor mainly of an insulating resin in a solvent mainly composed of an organic solvent. 2. The electrolytic capacitor according to claim 1, wherein the precursor of the insulating resin is 4,4′-diaminodiphenyl ether represented by the following formula and 1,2,4,5-benzenetetracarboxylic anhydride. Electrolytic solution for driving.

  3. The electrolytic solution for driving an electrolytic capacitor according to claim 1, wherein the addition amount of the insulating resin precursor is 0.5 to 20.0 wt%, respectively. An electrolytic capacitor using the electrolytic solution for driving an electrolytic capacitor according to any one of claims 1 to 3.