JPH07263287A - Sealing rubber for aluminum electrolytic capacitor - Google Patents

Abstract

PURPOSE:To provide a sealing rubber, for an aluminum electrolytic capacitor, whose moldability is improved and whose productivity and reliability are enhanced at the same time. CONSTITUTION:A fluororesin modifier is added to butyl rubber, and this mixture is thermocompression-molded to a desired shape and heated and treated additionally in the air. Thereby, since the modifier 2 is formed so as to be oriented on the surface of a sealing rubber 1A, it is possible to obtain the sealing rubber, for an aluminum electrolytic capacitor, whose life is improved, whose swelling property due to an electrolytic solution is dropped, whose mutual fusion property is dropped and whose productivity and reliability are enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing rubber for an aluminum electrolytic capacitor used to prevent leakage of an electrolytic solution impregnated in a capacitor element housed in an aluminum case of an aluminum electrolytic capacitor.

[0002]

2. Description of the Related Art A conventional sealing rubber for aluminum electrolytic capacitors will be described with reference to the drawings.

FIG. 3 is a sectional view showing the structure of an aluminum electrolytic capacitor. In FIG. 3, reference numeral 1 denotes a sealing rubber, and a capacitor element 3 to which an external lead wire 4 is connected is housed in an aluminum case 7 together with an electrolytic solution 5. Then, the sealing rubber 1 is fitted into the opening of the upper surface of the aluminum case 7 by inserting the external lead wire 4, and the sealing rubber 1 is inserted from the outer peripheral portion of the aluminum case 7 to prevent the sealing rubber 1 from coming off. The case drawing portion 6 is formed so as to be pressed against each other and assembled.

FIG. 4 is a perspective view showing a sealing rubber 1 used in the aluminum electrolytic capacitor shown in FIG. 3, and the sealing rubber 1 is molded from butyl rubber, ethylene propylene rubber or the like. In order to improve the releasability, stearic acid alone or a metal stearate was used, and a fluororesin or a silicone resin was applied to the mold as an external mold release agent and used for molding. .

[0005]

However, the above-mentioned conventional structure has the following problems.

(1) The sealing rubber 1 molded from butyl rubber or ethylene propylene rubber has a poor releasability at the time of molding, and in particular, the releasability is particularly poor when a peroxide-vulcanized butyl rubber is used. That is a bottleneck in productivity. In order to solve this, an increase in the amount of the internal release agent will improve the amount, but there is a problem that the amount cannot be increased because it is inversely proportional to the product life.

(2) There is a problem with respect to life (solvent permeability), and if it is combined with a fluororesin to solve the problem, the effect is great, but the cost, the combination technique, and the mechanical reliability of the combined surface are large. Had the problem of.

(3) Butyl rubber has a mutual fusion property such that it is fused when they are overlapped with each other, which causes a trouble that the sealing rubber 1 is fused during transportation of the capacitor assembling equipment.

The present invention solves these conventional problems,
An object of the present invention is to provide a sealing rubber for an aluminum electrolytic capacitor, which can improve productivity and reliability at the same time.

[0010]

In order to solve the above-mentioned problems, the sealing rubber for an aluminum electrolytic capacitor according to the present invention has a fluorocarbon resin surface modifier made of an acrylic oligomer having a perfluoroalkyl chain added to the rubber compound. The above material is used as a base material, and the base material is molded into a desired shape to obtain a sealing rubber.

[0011]

With this configuration, the perfluoroalkyl chain of the fluororesin surface modifier added to the rubber compound is oriented on the surface of the molded sealing rubber, and the fluororesin layer is formed on the surface of the sealing rubber. Since it is formed, excellent effects such as releasability, water repellency, low electrolytic solution permeability, non-fusing ability, and low friction coefficient can be obtained.

[0012]

EXAMPLES One example of the present invention will be described below by taking a peroxide vulcanized butyl rubber as an example of a material for a sealing rubber.

First, 10 butyl rubber XL-10000 was used.
0 parts, 3 parts of polybutadiene RB810, 100 parts of ST kaolin clay, 1 part of lead stearate, 30 parts of carbon black (MPF) and 1 part of anti-aging agent RD are mixed and kneaded with a kneader.

Since the amounts of ST kaolin clay and carbon black are large, they are charged in several times. Further, kneading is performed at a temperature of 100 ° C. or lower for about 30 minutes to prepare a rubber compound.

Next, per 100 parts of butyl rubber, 3 parts of peroxide Perk Mill D and 0.5 to 4 parts of a fluorine-based resin surface modifier (trade name: Megafac CC-ZA: manufactured by Dainippon Ink and Chemicals, Inc.) ) Is added and kneaded with a hot roller at 80 ° C. to prepare a sheet.

Next, using this compound, a sealing rubber (φ9 mm, 3.5 mmt) and a rubber sheet of 2 mmt were made 160
Molding was carried out under conditions of 100 ° C / cm ² and 5 minutes. After completion of the molding, a heat treatment of heating in air at 150 ° C. for 30 minutes was performed to orient the fluororesin surface modifier.

By making the sealing rubber 1A in this manner, the fluororesin surface modifier added to the rubber compound is shown in FIG. 1 by the heat and pressure (in the mold) and the heating in air during molding. Thus, the perfluoroalkyl chain 2 is oriented on the surface of the molded sealing rubber 1A, which provides excellent effects such as mold releasability, water repellency, low electrolytic solution permeability, non-fusion resistance, and low friction coefficient. It will come to exert.

The orientation of the perfluoroalkyl chain 2 is more effective in the heat treatment in air than in the heating during molding.

The sealing rubber 1 of the present invention thus constructed
As shown in FIG. 2, the effect of the fluorine-based resin surface modifier added to A is drastically decreased to 1% in terms of dynamic friction coefficient and almost saturated, and even if the amount of addition is further increased. You can see that the effect does not change.

The effect before the heat treatment is small, which is only about 1/3 of the value shown in FIG. Further, an aluminum electrolytic capacitor of 10 V and 100 μF was prototyped with the molded sealing rubber 1A, and the weight loss due to the permeation of the electrolytic solution in the 105 ° C. load life test was 30%.

In the assembly process, the sealing rubber 1A is also used.
As a result of carrying by using the parts feeder, the carrying trouble did not occur even without using the silicon-based mold release agent which was conventionally required.

On the other hand, the permeability of the electrolytic solution (gamma butyrolactone) by the rubber sheet alone is 1/2 that of the conventional product.
Could be reduced to

As described above, the sealing rubber 1A for an aluminum electrolytic capacitor according to the present invention has a structure in which the perfluoroalkyl chains are oriented on the surface of the sealing rubber 1A. improves.

Since the water repellency is improved and the electrolyte permeability is decreased, the swelling of the rubber is reduced, and the capacity change and the life are improved.

Since the friction coefficient of the rubber surface is reduced and the mutual fusion property is lost, the sealing rubber 1 in the assembly process is
There are many effects such as elimination of troubles caused by the transportation of A, and a great effect can be obtained in improving the productivity of the aluminum electrolytic capacitor and improving the product life.

[0026]

As described above, the sealing rubber for an aluminum electrolytic capacitor according to the present invention has releasability because about 1/3 of the surface of the fluororesin surface modifier added to the rubber compound is molded. When it is activated and further heated in air, the remaining modifier is oriented on the surface to form a composite of rubber and fluororesin, which improves water repellency and decreases electrolyte permeability. The coefficient of friction decreases,
The mutual fusion property is eliminated, and the productivity and reliability of the aluminum electrolytic capacitor can be improved at the same time.

[Brief description of drawings]

FIG. 1 is a structural model diagram showing a surface state of a sealing rubber for an aluminum electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the addition amount of the fluororesin surface modifier according to the example and the dynamic friction coefficient.

FIG. 3 is a front sectional view showing the structure of an aluminum electrolytic capacitor.

FIG. 4 is a perspective view showing a sealing rubber.

[Explanation of symbols]

 1,1A Seal rubber 2 Perfluoroalkyl chain 3 Capacitor element 4 Externally drawn lead wire 5 Electrolyte solution 6 Case drawing part 7 Aluminum case

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area C08L 23/22 LCJ // (C08L 23/22 27:12 9:00)

Claims (1)

[Claims] 1. A sealing rubber for an aluminum electrolytic capacitor, which is obtained by molding a base material obtained by adding a fluorocarbon resin surface modifier made of an acrylic oligomer having a perfluoroalkyl chain to a rubber compound into a desired shape. .