JP4650597B2 - Sealing body for electrolytic capacitor and manufacturing method thereof - Google Patents

Description

【００３４】
表１の結果より従来例では電解液のガス抜けが大きいため、無負荷時で30mg、有負荷時において50mg実施例が重量減少の抑制がなされている。
【００３５】
次に、寿命試験後の外観を比較した結果を表２に示す。
【００３６】
【表２】

【００３７】
従来例は、封口体が空気中の酸素に接触したことにより、ゴム表面にひび割れが発生したが、実施例では、外観異常は発生していない。すなわち、積層シートが酸素を遮断し、経時劣化が少なかったものと考えられる。
【００３８】
【発明の効果】
本発明によれば、積層フィルムを貼付けすることで電解液の透過性が低減する。このため、電解コンデンサの長寿命化を図ることができる。
【００３９】
そして、ゴム表面が被覆されることにより空気との接触が遮断されるので封口ゴムの酸化が抑制され、封口ゴムに生じるひび割れ、硬化等の発生頻度が低下する。
【００４０】
また、超高分子量ポリエチレンフィルムは、動摩擦係数が低いため本発明の三層の表面層とすることにより、加工時の成形金型からの離型性が向上する。
【００４１】
さらに、超高分子量ポリエチレンフィルムと弾性ゴムとが接合する。すなわち、フィルムまたはゴム表面の改質等をすることなく接合可能である。
【図面の簡単な説明】
【図１】本発明に係る電解コンデンサ用封口ゴムおよびその製造方法を示す説明図である。
【図２】従来の電解コンデンサの構成を示す断面図である。
【符号の説明】
２ 下金型
４ 弾性ゴム
６ 積層シート
８ 上金型[0001]
[Industrial application fields]
The present invention relates to a sealing body of an electrolytic capacitor, and the sealing body relates to a structure in which a sealing body is laminated on a polymer layer of vinyl alcohol through an ultrahigh molecular weight polyethylene layer.
[0002]
[Prior art]
The structure of a conventional electrolytic capacitor will be described with reference to FIG. FIG. 2 is a cross-sectional view showing the structure of the electrolytic capacitor 10. The electrolytic solution is impregnated in a capacitor element 12 in which an anode foil and a cathode foil are wound together with a separator, and the capacitor element is stored in a bottomed cylindrical outer case 14. The opening end of the exterior case is sealed with a sealing body 16. In such an electrolytic capacitor, since the end portion of the outer case obtains the sealing of the electrolytic capacitor by caulking that includes lateral groove processing and curling processing, elastic rubber is usually used as the sealing body.
[0003]
[Problems to be solved by the invention]
In the electrolytic capacitor, there has been a problem that the electrolytic solution impregnated in the capacitor element is gradually reduced by permeating the sealing body, thereby causing a decrease in capacitance. Therefore, one of the required characteristics of the electrolytic capacitor sealing body is that the permeability of the electrolytic solution is low. Conventionally, as a means for improvement, it has been dealt with by changing the type and amount of rubber filler. However, since the absolute level of characteristics is largely attributed to the molecular structure of the polymer, there has been a problem that it is difficult to make a breakthrough improvement.
[0004]
Japanese Patent Laid-Open No. 7-307253 has already proposed a method in which a metal or resin is bonded to the surface of the sealing body to reduce the electrolyte permeability. However, in this method, adhesion to the peroxide vulcanized rubber requires an adhesive and is difficult unless surface treatment such as modification by sputter etching on the surface of the sealing body or the metal to be attached or the resin surface is performed. There was a problem that there was.
[0005]
Accordingly, an object of the present invention is to prevent the electrolytic capacitor from degrading by reducing the permeability of the electrolyte at the sealing site, and to prevent the sealing body from cracking and hardening by blocking the contact between the sealing body and the air. There is to do.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the electrolytic capacitor sealing body manufacturing method according to the present invention is characterized in that a rubber kneaded by adding a vulcanizing agent to an unvulcanized rubber is poured into a lower mold, and vinyl alcohol is placed on the rubber. Put a laminated sheet consisting of a polymer sheet and ultra-high molecular weight polyethylene film, contact rubber with added vulcanizing agent on the ultra-high molecular weight polyethylene film side, cover the upper mold, and heat and press to form It is characterized by cutting out .
[0010]
An organic peroxide vulcanizing agent is preferably used as the vulcanizing agent.
[0011]
The sealing body for an electrolytic capacitor according to the present invention is obtained by attaching a composite film in which ultrahigh molecular weight polyethylene / ethylene vinyl alcohol / ultra high molecular weight polyethylene is laminated in three layers to elastic rubber.
[0012]
Ultra high molecular weight polyethylene has a very high average molecular weight of 1,000,000 to 5,000,000, so it is stable against chemicals, has very little water absorption and has excellent electrical properties. Furthermore, vulcanization adhesion with rubber capable of peroxide vulcanization is possible without performing surface treatment of the elastic rubber.
[0013]
A vinyl alcohol copolymer is a substance obtained by copolymerizing vinyl alcohol, has heat-melting moldability and high gas barrier properties.
[0014]
For this reason, when a copolymer layer of high molecular weight polyethylene and vinyl alcohol is laminated, an effect of low gas permeability can be obtained.
[0015]
As the vinyl alcohol polymer, polyvinyl alcohol and ethylene vinyl alcohol are used in the present invention. Ethylene vinyl alcohol is a copolymer resin copolymerized with ethylene.
[0016]
Furthermore, since the ultrahigh molecular weight polyethylene film has a low dynamic friction coefficient, the release property from the molding die during processing is improved by using the three-layer surface layer of the present invention.
[0017]
Further, in the production method of the present invention, in a laminated sheet composed of an ultrahigh molecular weight polyethylene film and a polymer sheet of vinyl alcohol, a rubber layer vulcanized with peroxide is brought into contact with the ultrahigh molecular weight polyethylene film side and heated to form. As a result, the ultra high molecular weight polyethylene film and the elastic rubber are joined. That is, bonding is possible without modifying the film or rubber surface.
[0018]
Examples of the vulcanization method include peroxide vulcanization, resin vulcanization, other quinoside vulcanization, sulfur vulcanization, polyamine vulcanization, and polyol vulcanization. Among these, rubber vulcanized with an organic oxide vulcanizing agent can be vulcanized and bonded to ultrahigh molecular weight polyethylene by vulcanization, and the heat resistance of the rubber is improved. For this reason, it is suitable as a sealing body for an electrolytic capacitor used in a high-temperature environment because deterioration due to heat is reduced and life characteristics can be improved.
[0019]
Examples of the organic peroxide vulcanizing agent include ketone peroxides, peroxyketals, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, peroxyesters and the like. More specifically, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, t-butylperoxybenzoate, n-butyl-4,4-bis (t-butylperoxy) ) Valerate, α, α'-bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide And di-t-butyl peroxide.
[0020]
【Example】
Hereinafter, the embodiment will be described in more detail with reference to FIG. In the sealing body according to the present invention, the laminated sheet 6 and the elastic rubber 4 are laminated as shown by (6) in FIG.
[0021]
The laminated sheet 6 is made by laminating the product name “Eval” manufactured by Kuraray Co., Ltd. as an ethylene vinyl alcohol film, and the product name “Technol” manufactured by Otsuka Techno Co. A laminated film having a three-layer structure of molecular weight polyethylene is obtained. The thickness of the upper ultra-high molecular weight polyethylene is 80 μm, the intermediate layer ethylene vinyl alcohol is 30 μm, and the lower ultra-high molecular weight polyethylene is 80 μm. Moreover, ultra high molecular weight polyethylene and ethylene vinyl alcohol are joined together via a urethane or epoxy adhesive.
[0022]
Although technol has a melting point of 136 ° C., it has a high molecular weight and therefore does not melt into a liquid state even at a temperature higher than the melting point.
[0023]
The elastic rubber 4 is composed of any one of ethylene propylene diene rubber, partially crosslinked butyl rubber, and resin vulcanized butyl rubber capable of organic peroxide vulcanization. In this embodiment, it is composed of partially crosslinked butyl rubber.
[0024]
Next, the manufacturing method of the sealing body according to the present invention will be described using (1) to (6) in FIG.
[0025]
First, a lower mold 2 for forming a sealing body as shown in (1) of FIG. 1 is shown. The mold 2 is provided with recesses at regular intervals according to the number of sealing bodies to be created.
[0026]
Secondly, as shown in (2) in FIG. 1, a rubber obtained by adding an organic peroxide vulcanizing agent to an unvulcanized rubber and kneading is added.
[0027]
Third, as shown in (3) of FIG. 1, a laminated sheet 6 is further laminated on the rubber layer.
[0028]
Fourth, the upper mold 8 is mounted on the laminated sheet 6 as shown in (4) of FIG. Furthermore, it heats and pressurizes and shape | molds and obtains the continuous body of a sealing body.
[0029]
Fifthly, as shown in (5) in FIG. 1, the continuous body of the sealing body is taken out from the mold. At this time, since the ultra high molecular weight polyethylene does not adhere to the upper mold 8, it can be easily peeled off from the upper mold 8. By cutting the continuous body of the sealing bodies along the cutting line shown in FIG. 5, the individual sealing bodies shown in FIG. 6 are obtained.
[0030]
The conditions for vulcanization are 15 minutes at 157 ° C. when dicumyl peroxide (1 minute half-life 175 ° C.) is used as a rubber vulcanizing agent.
[0031]
When 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane (one minute half-life temperature 149 ° C.) is used as a rubber vulcanizing agent, the conditions for vulcanization are 5 at 150 ° C. For minutes.
[0032]
Furthermore, an experiment was performed comparing the embodiment of the present invention with the conventional example. In Examples, an electrolytic capacitor was manufactured using a sealing body to which a laminated film was attached. Its size is φ16 × 25L, and its rated voltage and rated capacitance are 25 WV 1200 μF. On the other hand, the conventional example is an electrolytic capacitor manufactured using a sealing body to which a laminated film is not attached. The test conditions of the life test were 150 ° C. and 2000 hours, with rated voltage applied and with no load left. The results are shown in Table 1.
[0033]
[Table 1]

[0034]
From the results shown in Table 1, since the outgassing of the electrolytic solution is large in the conventional example, the weight reduction is suppressed in the 30 mg example when there is no load and the 50 mg example when there is a load.
[0035]
Next, Table 2 shows the result of comparing the appearance after the life test.
[0036]
[Table 2]

[0037]
In the conventional example, cracks occurred on the rubber surface as a result of the sealing body coming into contact with oxygen in the air, but in the examples, no appearance abnormality occurred. That is, it is considered that the laminated sheet blocked oxygen and was less deteriorated with time.
[0038]
【The invention's effect】
According to this invention, the permeability | transmittance of electrolyte solution reduces by sticking a laminated | multilayer film. For this reason, the lifetime of the electrolytic capacitor can be extended.
[0039]
And since the contact with air is interrupted by covering the rubber surface, the oxidation of the sealing rubber is suppressed, and the frequency of occurrence of cracks, curing and the like occurring in the sealing rubber is reduced.
[0040]
In addition, since the ultrahigh molecular weight polyethylene film has a low dynamic friction coefficient, the release property from the molding die during processing is improved by using the three-layer surface layer of the present invention.
[0041]
Furthermore, the ultra high molecular weight polyethylene film and the elastic rubber are joined. That is, bonding is possible without modifying the film or rubber surface.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a sealing rubber for an electrolytic capacitor and a method for producing the same according to the present invention.
FIG. 2 is a cross-sectional view showing a configuration of a conventional electrolytic capacitor.
[Explanation of symbols]
2 Lower mold 4 Elastic rubber 6 Laminated sheet 8 Upper mold

Claims (2)

A rubber obtained by adding a vulcanizing agent to an unvulcanized rubber and pouring the kneaded rubber is poured into a lower mold, and a laminated sheet composed of a vinyl alcohol polymer sheet and an ultrahigh molecular weight polyethylene film is placed on the rubber, and the ultrahigh molecular weight polyethylene is placed. A method for producing a sealing body for an electrolytic capacitor, comprising contacting a rubber to which a vulcanizing agent is added on a film side, covering an upper mold, heating and pressurizing and molding into a predetermined shape. The method for producing a sealing body for an electrolytic capacitor according to claim 1 , wherein the vulcanizing agent is an organic peroxide vulcanizing agent.

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