JP2004296932A - Seal for electrolytic capacitor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seal for an electrolytic capacitor which can withstand the use at a temperature as high as 150°C for a long period of time. <P>SOLUTION: A seal rubber is immersed into a solution of 50 wt% or less containing polyimide silicon dissolved in a ketone-based solvent, pulled up, and dried at a temperature of 40-100°C for 1-2 hours for polymerization. The thus-obtained seal rubber having a PISi (polyimide silicon i) layer formed thereon is mounted onto an opening of an encapsulating case in which a capacitor element having an electrolytic solution immersed therein, and the opening is drawn to seal the opening. After the opening is sealed by the drawing, the case is reformed to obtain an electrolytic capacitor which can have a long-time durability at a temperature as high as 150°C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１６】
表１から明らかなように、実施例の電解液の透過量は、いずれの場合も従来例に比べて１７〜２０％減となっており、封口ゴムの表面にＰＩＳｉ層を形成することにより、封口ゴムの表面からの熱酸化が抑制されていることが示された。また、電解コンデンサでは一般に、電解液の保持量が減少すると静電容量が低下し、ｔａｎδが上昇することが知られているが、実施例では電解液の減少が大幅に抑制されているため、電気特性の劣化を抑制することができると考えられる。
【００１７】
【発明の効果】
以上述べたように、本発明によれば、１５０℃の高温長時間使用に耐えることのできる電解コンデンサ用封口体及びその製造方法を提供することができる。
【図面の簡単な説明】
【図１】電解コンデンサの構成を示す断面図
【符号の説明】
１…コンデンサ素子
２…外装ケース
３…封口ゴム[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sealing body for an electrolytic capacitor and a method for manufacturing the same, and more particularly, to a sealing body for an electrolytic capacitor that can withstand use at a high temperature of 150 ° C. and a method for manufacturing the same.
[0002]
[Prior art]
A conventionally used electrolytic capacitor is configured as shown in FIG. That is, an electrode foil provided with a lead wire serving as an electrode lead-out means is wound around a separator to form a capacitor element 1, and the capacitor element 1 impregnated with a driving electrolyte is placed in a bottomed cylindrical outer case 2. To store. Then, the sealing body 3 is attached to the opening of the outer case, and then the opening is sealed by caulking to form an electrolytic capacitor.
[0003]
Usually, a sealing rubber made of butyl rubber or ethylene propylene rubber is used as the sealing body for the electrolytic capacitor. In addition, as an electrolytic solution to be impregnated in a capacitor element of a small, low-impedance, 100 WV class electrolytic capacitor, conventionally, γ-butyrolactone is used as a main solvent, and a tertiary salt such as phthalic acid and maleic acid is used as a solute. Etc. are known.
[0004]
[Problems to be solved by the invention]
The above-mentioned conventional electrolytic capacitor is used at a high temperature of 125 ° C., but in recent years, the operating environment temperature of electrolytic capacitors used for electric components of automobiles and inverter lighting has been raised to 150 ° C. Therefore, conventional electrolytic capacitors cannot withstand long-time use at 150 ° C.
[0005]
Thus, it has been found that the reason why the conventional electrolytic capacitor cannot be used at a high temperature of 150 ° C. for a long time is the heat resistance of the conventional sealing rubber. That is, when used at a high temperature of 150 ° C., the conventional sealing rubber undergoes thermal oxidative deterioration, rubber characteristics are deteriorated, rubber strength is reduced, and airtightness is reduced. The characteristics of the electrolytic capacitor deteriorate. Furthermore, the vapor pressure of the electrolytic solution solvent inside the electrolytic capacitor increases, the amount of permeation from the sealing rubber increases, and the characteristics of the electrolytic capacitor deteriorate.
[0006]
SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems of the related art, and an object of the present invention is to provide a sealing body for an electrolytic capacitor capable of withstanding a long time use at a high temperature of 150 ° C. and a method of manufacturing the same. Is to provide.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present inventor has conducted intensive studies on means capable of preventing thermal oxidative deterioration of the sealing rubber even when used at a high temperature of 150 ° C. for a long time. It has been completed.
That is, it was found that the above-mentioned problem can be solved by forming an insulating layer made of polyimide silicon on the surface of the sealing rubber in advance.
[0008]
(Polyimide silicon)
As the polyimide silicon solution for coating the surface of the sealing rubber, a solution of polyimide silicon (PISi) dissolved in a ketone solvent at 50 wt% or less, preferably 5 to 30 wt%, more preferably 10 to 25 wt% is used. If the amount exceeds this range, the fluidity of the polyimide silicon solution is reduced, so that uniform coating cannot be performed.
Note that, as the ketone solvent, it is preferable to use cyclohexane, acetone, methyl ethyl ketone, or the like.
[0009]
(Method of forming polyimide silicon layer)
As a method of forming a polyimide silicon layer (hereinafter, referred to as a PISi layer) on the surface of the sealing rubber, the sealing rubber is immersed in the above polyimide silicon solution, pulled up, dried at 40 to 100 ° C, and dried at 150 to 200 ° C. A method of heating and polymerizing at 1 ° C. for 1 to 2 hours is preferable.
In this way, the sealing rubber having the PISi layer formed on the surface is attached to the opening of the outer case containing the capacitor element impregnated with the electrolytic solution, and the opening is sealed by drawing, followed by re-formation. Create an electrolytic capacitor.
[0010]
(Part where the PISi layer is formed)
The portion where the PISi layer is to be formed needs to be formed on the upper surface of the electrolytic capacitor when it is formed. More preferably, it is desirable to form on the upper and lower surfaces of the sealing rubber. Furthermore, when a PISi layer is formed on the side surface of the sealing rubber, that is, the contact surface with the outer case, the progress of thermal oxidation from this surface can be suppressed, and the electrolytic solution from the contact surface between the sealing body and the outer case can be further prevented. Can be suppressed, and a more excellent effect can be obtained.
Further, when formed on the inner wall portion of the through hole, the progress of thermal oxidation due to heat transfer from the lead wire can be suppressed, so that the diffusion of the electrolyte from between the lead wire and the through hole can also be suppressed. .
[0011]
(Action / Effect)
The sealing rubber of the present invention has a high heat resistance on at least the upper surface thereof, and a PISi layer having a low permeability to the solvent of the electrolytic solution is formed. Deterioration can be prevented. As a result, the permeation of the electrolytic solution is suppressed, and the amount of the solvent of the electrolytic solution permeated from the rubber is suppressed, so that it can withstand a high temperature of 150 ° C. and a long time use.
[0012]
That is, the deterioration of the sealing rubber at high temperatures is considered to be due to the progress of thermal oxidation from the surface. Therefore, if a PISi layer having high heat resistance is formed on the rubber surface, the thermal oxidation from the surface is suppressed, and the rubber properties are reduced. Is suppressed. In addition, when the decrease in the solvent of the electrolytic solution is suppressed, it is possible to suppress a decrease in capacitance and an increase in tan δ due to a decrease in the amount of retained electrolytic solution.
Further, since PISi has good adhesiveness to rubber, the PISi layer does not peel off from the sealing rubber, and is excellent in reliability.
[0013]
【Example】
Hereinafter, the effects of the present invention will be specifically described using examples.
(Example)
The sealing rubber made of butyl rubber was immersed in a 20 wt% solution of polyimide silicon in cyclohexane, pulled up, dried at 100 ° C., heated at 150 ° C. for 1 hour and polymerized to form a PISi layer on the surface of the sealing rubber. On the other hand, the capacitor element impregnated with the electrolytic solution was housed in an outer case, and the opening was sealed with the above sealing rubber by drawing, followed by re-chemical formation to produce an electrolytic capacitor. In addition, a mixed solution of 50 wt% of sulfolane, 25 wt% of γ-butyrolactone, and 25 wt% of 1-ethyl-2,3-dimethylimidazolinium phthalate was used as the electrolytic solution.
The size of the electrolytic capacitor is 22φ × 35L.
[0014]
(Conventional example)
An electrolytic capacitor was prepared in the same manner as in the above example using a sealing rubber having no PISi layer formed thereon.
[0015]
[Comparison result]
The electrolytic capacitors of the examples and the conventional examples prepared as described above were allowed to stand at 150 ° C. for 500 hours, 1000 hours, and 1500 hours, and the permeation amount of the electrolytic solution was measured. The results shown in Table 1 were obtained. Was done.
[Table 1]

[0016]
As is evident from Table 1, the permeation amount of the electrolyte solution of the examples was reduced by 17 to 20% in each case as compared with the conventional example. By forming the PISi layer on the surface of the sealing rubber, It was shown that thermal oxidation from the surface of the sealing rubber was suppressed. Also, in an electrolytic capacitor, it is generally known that the capacitance decreases and the tan δ increases when the retained amount of the electrolytic solution decreases, but in the examples, since the decrease in the electrolytic solution is greatly suppressed, It is considered that the deterioration of the electric characteristics can be suppressed.
[0017]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a sealing body for an electrolytic capacitor that can withstand long-term use at a high temperature of 150 ° C. and a method for manufacturing the same.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the configuration of an electrolytic capacitor.
1: Capacitor element 2: Outer case 3: Seal rubber

Claims (3)

What is claimed is: 1. A sealing body for an electrolytic capacitor, comprising: a polyimide silicon layer formed on a surface of the sealing body. The sealing body used for sealing the electrolytic capacitor is immersed in a polyimide silicon solution, pulled up, dried at 40 to 100 ° C, heated at 150 to 200 ° C for 1 to 2 hours, and polymerized by electrolytic polymerization. A method for manufacturing a sealing body for a capacitor. The method for producing a sealing body for an electrolytic capacitor according to claim 2, wherein the polyimide silicon solution is a solution of polyimide silicon dissolved in a ketone-based solvent at 50 wt% or less.

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