JPH0661109A - Electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain an elastic sealing material having improved antipermeability and the like of a driving electrolyte by adding a specific quantity of a high class fatty acid derivative to the compound mainly composed of ethylene propylene rubber, isobutylene isoprene rubber and natural rubber. CONSTITUTION:On elastic aperture sealing material 4, an anode lead-out terminal 2, led out from a capacitor element 1, and a cathode lead-out terminal 3 are penetratingly provided, and the aperture part of a bottomed cylindrical case 5, where the capacitor element is housed, is provided. The mixture, formed by adding and kneading 0.5 to 8 pts.wt. of high grade fatty acid ester, high grade fatty acid derivative ester or high grade fatty acid metal salt to the compound which is formed by mixing a reinforcement agent, a cross-linking agent and a crosslinking assistant agent into 100 pts.wt. of EPDM, IIR or natural rubber, is used as the elastic aperture sealing material 4. As a result, the primary factors for deterioration of various characteristics can be improved sharply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic capacitor having an improved elastic sealing member which seals the opening of a bottomed cylindrical case containing a capacitor element impregnated with a driving electrolytic solution.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 1, an electrolytic capacitor impregnated with a driving electrolytic solution is a capacitor element 1 formed by winding a separator between an aluminum anode foil and an aluminum cathode foil. Impregnated with the driving electrolyte,
After arranging the elastic sealing body 4 by penetrating the anode lead-out terminal 2 and the cathode lead-out terminal 3 led out from the capacitor element 1, the capacitor element 1 is attached to the bottomed cylindrical case 5 made of metal such as aluminum. This is a cylindrical case with a bottom.
The elastic sealing body 4 is provided inside the opening of the case 5, and the tip of the opening of the bottomed cylindrical case 5 is wound and sealed.

However, the requirement for the elastic sealing body 4 of the electrolytic capacitor constructed as described above is such that the permeation suppressing force of the driving electrolyte is large in the growing demand for high reliability and long life. Further, it is necessary to greatly contribute to the prevention of the invasion of the substrate cleaning agent in the cleaning process performed for the purpose of removing the flux attached to the substrate on which this type electrolytic capacitor is mounted.

Materials conventionally used as elastic sealing bodies for these electrolytic capacitors are ethylene propylene rubber (hereinafter referred to as EPDM) or isobutylene isoprene rubber (hereinafter referred to as IIR). The sealing body 4 has not been able to sufficiently meet the recent demand for high reliability and long life.

That is, since the elastic sealing body 4 made of EPDM has a small permeation suppressing force for the driving electrolytic solution, the permeation diffusion of the driving electrolytic solution is large, resulting in a decrease in capacitance and t.
An δ is large, and further, corrosion occurs due to the intrusion of the substrate cleaning agent in the cleaning process, and it has not been possible to sufficiently meet the recent demand for high reliability and long life. Also EP
In the elastic sealing body 4 made of DM, the elastic sealing bodies 4 easily stick to each other in the cleaning process before assembling and the alignment process in assembling the capacitor, which causes corrosion due to incomplete cleaning and lowers production efficiency. There was also.

On the other hand, the elastic sealing body 4 made of IIR has a larger permeation suppressing force of the driving electrolyte solution than that made of EPDM and can improve the characteristic deterioration to some extent.
Not only this does not completely meet the demand for high reliability and long service life, but also the elastic sealing body 4 sticks to each other more easily than the one made of EPDM, and it takes a long time for the vulcanization process during molding, Since it has problems such as high cost, it has been practically restricted.

Therefore, there is also an electrolytic capacitor technology in which a sealing body in which a fluororesin sheet is closely bonded to the surface of a rubber-like elastic body as described above is used and the fluororesin sheet surface is the outer surface. It has been put to practical use and has a great effect in preventing the permeation of the driving electrolyte and the invasion of the substrate cleaning agent. Because of the directionality of the surface,
It is necessary to reliably detect the orientation of the capacitor during the assembly process, which is a factor that complicates the assembly process.

In addition, in the cleaning step before assembling and the aligning step in assembling the capacitor, aside from the contact between the fluororesin sheet surface and the rubber surface, the contact between the rubber surfaces or the side surfaces of the sealing body The problem that the sealed comrades stick to each other was not solved when they contacted each other.

Further, as a technique for preventing the elastic sealing members from sticking to each other, a technique using a rubber-like elastic body in which a plurality of wart-like protrusions or a plurality of linear protrusions are integrally provided on both front and back surfaces has been put into practical use. Although the effect of preventing sticking of the face-to-face comrades is enhanced, when the side-to-side comrades of the sealer come into contact with each other as in the case described above, the problem that the seal-mates stick to each other has not been solved.

[0010]

As described above, in the electrolytic capacitor using the elastic sealing body having the above-described structure which has been generalized in the past, the electrolytic solution for driving which is required as the elastic sealing body of these electrolytic capacitors is required. Permeation resistance Substrate cleaning agent penetration resistance Not all requirements such as sticking resistance during the cleaning process and the alignment process during capacitor assembly have been fully satisfied, and there have been practical problems to be solved.

In order to solve the above problems, the present invention focuses on higher fatty acid esters, which are generally used by the inventor of the present invention to improve the mold flow of a rubber molded product, as a result of various studies. By improving the rubber material that constitutes the elastic sealing body by limiting the amount of addition, the above-mentioned requirements required for the elastic sealing body of the electrolytic capacitor are improved, and factors of deterioration of various characteristics are improved and have high practical value. It is intended to provide an electrolytic capacitor.

[0012]

SUMMARY OF THE INVENTION An electrolytic capacitor according to the present invention accommodates a capacitor element having a bottomed cylindrical case impregnated with a driving electrolytic solution, and has an elastic opening at the bottomed cylindrical case. In an electrolytic capacitor sealed with a sealing body, the elastic sealing body is a higher fatty acid ester in a basic compound in which 100 parts of ethylene propylene rubber, isobutylene isoprene rubber or natural rubber is appropriately mixed with a reinforcing agent, a crosslinking agent and a crosslinking aid. And 0.5 to 8 parts of a higher fatty acid derivative ester or a higher fatty acid metal salt are added, kneaded and crosslinked.

[0013]

According to the present invention, since the amount of the higher fatty acid ester, the higher fatty acid derivative ester or the higher fatty acid metal salt to be added and mixed in the basic compound is 0.5 to 8 parts, the elastic sealing member is constituted. The higher fatty acid ester, the higher fatty acid derivative ester or the higher fatty acid metal salt becomes supersaturated beyond the solubility within the composition, and the higher fatty acid ester, the higher fatty acid derivative ester or the higher fatty acid metal salt remains constant on the surface of the elastic sealing body. The sealing body is uniformly bloomed with a thickness of.

[0014]

EXAMPLE An example of the present invention will be described below.

Since the present invention is the same as that illustrated in FIG. 1 except for the elastic sealing body structure, it will be described with reference to FIG.

That is, as shown in FIG. 1, a capacitor element 1 formed by winding an aluminum anode foil and an aluminum cathode foil with a separator interposed therebetween is impregnated with a driving electrolytic solution, and the capacitor element 1 is led out from this capacitor element 1. After arranging the elastic sealing body 4 by penetrating the anode lead-out terminal 2 and the cathode lead-out terminal 3, the capacitor element 1 is housed in a bottomed cylindrical case 5 made of metal such as aluminum. The elastic sealing body 4 is provided inside the opening of the bottom cylindrical case 5, and the tip of the opening of the bottomed cylindrical case 5 is wound and sealed. In this case, As the structure of the elastic sealing body 4, 100 parts of EPDM or I
0.5 to 8 parts of a higher fatty acid ester, a higher fatty acid derivative ester or a higher fatty acid metal salt is added to a basic compound in which 100 parts of IR is mixed with a reinforcing agent, a cross-linking agent and a cross-linking auxiliary which are usually used, and kneaded. It was obtained by doing.

According to the electrolytic capacitor having the above structure, 0.5 to 8 parts of higher fatty acid ester, higher fatty acid derivative ester or higher fatty acid metal salt is added and kneaded to the basic compound as the structure of the elastic sealing body 4. Since it is obtained, the higher fatty acid ester, the higher fatty acid derivative ester or the higher fatty acid metal salt becomes supersaturated beyond the solubility with the passage of time within the composition constituting the elastic sealing body 4, so that the surface of the elastic sealing body 4 is highly saturated. A fatty acid ester, a higher fatty acid derivative ester, or a higher fatty acid metal salt is uniformly bloomed with a constant thickness, and a higher thickness of the higher fatty acid ester or higher fatty acid derivative ester that covers the elastic sealing member 4 surface by this blooming phenomenon. Alternatively, the presence of the higher fatty acid metal salt can prevent the permeation of the driving electrolyte solution, and can be performed after the mounting on the substrate. The penetration of the detergent in step can be prevented.

Further, the higher fatty acid ester, the higher fatty acid derivative ester or the higher fatty acid metal salt having a constant thickness, which covers the surface of the elastic sealing body 4 by the blooming phenomenon, has no water solubility even when washed with water or boiled. A higher fatty acid ester of a certain thickness, which has a strong adhesion to the rubber surface and does not peel off, and which covers the surface of the elastic sealing body 4,
Since the higher fatty acid derivative ester or the higher fatty acid metal salt has good slipperiness, the problem that the elastic sealing bodies 4 stick to each other in a mixed state in the cleaning process before assembly and the alignment process during capacitor assembly is solved, and the efficiency of assembly work is improved. You can contribute greatly.

In the present invention, the addition amount of the higher fatty acid ester, the higher fatty acid derivative ester or the higher fatty acid metal salt to be added and kneaded to the basic compound is 0.5.
If the amount is less than 0.5 parts, the blooming effect is insufficient to achieve the intended purpose, and if it exceeds 8 parts, it is an essential requirement as an elastic sealing body. This is based on the reason that the physical properties, that is, the compression strain tends to be lost.

Next, a characteristic comparison between the present invention and the conventional example will be described based on the concrete results of the implementation. (Example-1) Invention A using an elastic sealing body obtained by adding 5 parts of pentaerythritol as a higher fatty acid ester to the basic compound of IIR, and a conventional example using an elastic sealing body consisting of IIR. As a result of examining the weight change (ΔW) of the capacitor with respect to the time of being left at 105 ° C.
It came to be shown in.

The sample of the present invention A and the conventional example B had a diameter of 5 mm and a length of 11 mm, and the driving electrolyte was γ.
It is made of butyrolactone and has a rated voltage of 25 V-100 μF. (Example-2) Invention B using an elastic sealing body obtained by adding 5 parts of pentaerythritol as a higher fatty acid ester to a basic compound of EPDM, and a conventional example using an elastic sealing body made of EPDM. As a result of examining the occurrence of corrosion with respect to time due to the difference in the size of each capacitor, the type of cleaning agent and the cleaning time, the results are shown in Tables 1 and 2.

The size of the capacitor as a sample,
The rating of 5mm x 11mm is 25V-100μF, 13
The rating of mm × 22 mm is 25V-470 μF. (Example-3) Inventive C using an elastic sealing body obtained by adding 5 parts of pentaerythritol as a higher fatty acid ester to a basic compound of EPDM, or pentaerythritol as a higher fatty acid ester to a basic compound of IIR. Invention D using an elastic sealing body formed by adding 5 parts of
And a conventional example using the elastic sealing body made of EPDM, or a conventional example using the elastic sealing body made of IIR, the part of the elastic sealing body sticking together within 8 hours due to the difference in the size of the elastic sealing body. As a result of examining the number of times of stopping, the results are shown in Table 3.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

As is clear from FIG. 2, the one of the present invention A has less change in weight (ΔW) of the capacitor with time as compared with the one of the conventional example A, and accordingly has less gas permeability, and thus the driving electrolyte solution. It means that the permeation suppressing power is excellent.

Further, as is clear from Tables 1 and 2, the invention B has a slight difference in cleaning agent and cleaning time as compared with the conventional example B, but the occurrence of corrosion of the capacitor element does not occur. This means that the cleaning agent has a small amount and has excellent penetration resistance.

Further, as is apparent from Table 3, in the invention C and the invention D, the number of times of stopping the part feeder is almost equal to that of the conventional example C and the conventional example D, and the elastic sealing members are the same. This means that it has excellent sticking resistance.

From the above-mentioned results, the elastic sealing body according to the present invention is required as the elastic sealing body in the above-mentioned electrolytic capacitor, the permeation resistance of the driving electrolyte solution, the penetration resistance of the substrate cleaning agent, the cleaning step and the capacitor. This has the effect of contributing to a significant improvement in requirements such as sticking resistance during the alignment process during the assembly process.

In the above embodiment, the basic compound is EPDM or IIR, but the same effect can be obtained by applying it to natural rubber.

[0031]

According to the present invention, it is possible to obtain an electrolytic capacitor in which various factors for characteristic deterioration are significantly improved, excellent life characteristics can be secured, and which contributes greatly to the improvement of work efficiency.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a general electrolytic capacitor.

FIG. 2 is a characteristic curve diagram showing a weight change (ΔW) of a capacitor with respect to time.

[Explanation of symbols]

 1 Capacitor Element 2 Anode Lead Terminal 3 Cathode Lead Terminal 4 Elastic Sealing Body 5 Bottomed Cylindrical Case

Claims (1)

[Claims] 1. An electrolytic capacitor comprising a bottomed cylindrical case containing a capacitor element impregnated with a driving electrolytic solution, and an opening of the bottomed cylindrical case being sealed with an elastic sealing member. In the compound in which the elastic sealing body is 100 parts by weight of ethylene propylene rubber, isobutylene isoprene rubber or natural rubber, a reinforcing agent, a cross-linking agent, and a cross-linking aid are appropriately mixed, and a higher fatty acid ester, a higher fatty acid derivative ester or a higher fatty acid metal salt is added to the compound. An electrolytic capacitor characterized by comprising 5 to 8 parts of an additive kneaded and crosslinked.