JPH08148391A - Sealing rubber for aluminum electrolytic capacitors - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a sealing rubber for an aluminum electrolytic capacitor, which can be used at high temperature for a long time. In addition, a method for easily and surely producing this sealing rubber is also provided. [Structure] The sealing rubber of the present invention has a rubber content of 1 to 200 μm.
It is sandwiched between plastic films. Both of them have high heat resistance and do not corrode aluminum, and plastics have a high gas barrier property. The rubber plays the elasticity of the sealing rubber, and the plastic film plays the gas barrier property. This satisfies all the properties required for the sealing rubber. According to the production method of the present invention, the plastic film and the rubber can be brought into close contact with each other while the rubber is crosslinked. That is, the kneaded rubber is poured into two cylindrical molds, and a plastic film is sandwiched between them to heat-crosslink the rubber. Since the excess film is dissolved and removed, no burr remains.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Aluminum electrolytic capacitors are small capacitors mainly used in televisions, video recorders, radios and the like. Nowadays, it is also used in cars and computers, and the production volume is increasing year by year. Aluminum electrolytic capacitor is a direct line 3-20mm, height 1
It has a cylindrical shape of 0 to 50 mm. The columnar part is a small can-shaped case made of aluminum foil, in which the paste electrolyte is contained. One side of the aluminum case is open and has a rubber stopper. The rubber stopper thus has the shape of a cylinder having the same diameter as the aluminum case and a height lower than that of the case. The rubber stopper has two thin holes, and leads from outside the container to inside the container are passed through. The present invention relates to this sealing rubber. (Fig. 1)

[0002]

2. Description of the Related Art Sealing rubber is mainly required to have the following three properties. 〇 Does not corrode aluminum. Aluminum foil is thin. If the sealing rubber contains something that corrodes aluminum, holes will be made in the aluminum. Corrosive substances are, for example, chloroprene rubber and halogen compounds. Such materials should not be used for the sealing rubber.

High heat resistance. In recent years, aluminum electrolytic capacitors have been widely used in cars and computers. Therefore, 100-
It may be exposed to a high temperature of 150 ° C for a long time. There has been a demand for a sealing rubber that can withstand such use.

High gas barrier property. The paste electrolyte of aluminum electrolytic capacitors includes ethylene glycol, dimethylformamide, γ-
Butyrolactone is used. Recently, γ- that can improve the characteristics of aluminum electrolytic capacitors
Butyrolactone has come to be widely used. γ−
Butyrolactone easily volatilizes at 60 ° C or higher. When the gas barrier property of the sealing rubber is low, γ-butyrolactone is volatilized through the sealing rubber. In particular, aluminum electrolytic capacitors used at high temperatures are strongly required to have a gas barrier property in the sealing rubber.

Next, a conventional sealing rubber will be described. Until a few years ago, aluminum electrolytic capacitors were mainly used for TVs, videos, etc. Also, ethylene glycol was mainly used as the electrolyte. At this time, the base rubber of the sealing rubber was a cheap natural rubber. Natural rubber is a rubber lacking heat resistance and gas barrier properties, but no problem occurred under the above-mentioned usage conditions. However, when it came to be used in cars and computers, heat resistance was first required. Therefore, ethylene propylene diene rubber, which has high heat resistance, has replaced natural rubber as the base rubber for the sealing rubber. Furthermore, in order to improve the characteristics of aluminum electrolytic capacitors, γ-butyrolactone has come to be used as an electrolytic solution, and a gas barrier property has also been required. Therefore, butyl rubber has become the base rubber of the sealing rubber instead of ethylene propylene diene rubber, which has a low gas barrier property.

Butyl rubber has the highest gas barrier property among rubbers. The sealing rubber using this as a base rubber can prevent volatilization of γ-butyrolactone. However, general-purpose butyl rubber has lower heat resistance than ethylene propylene diene rubber. Therefore, butyl rubber, which has high heat resistance, is used as the sealing rubber. It is a partially crosslinked butyl rubber that is peroxide crosslinked, or a butyl rubber that is resin vulcanized.
Both of them satisfy all the properties described above, but there is a problem in terms of productivity.

Peroxide cross-linked partially cross-linked butyl rubber is
The base rubber is partially crosslinked. Therefore, during kneading and molding, the flow is poor and it is difficult to handle. Therefore, it is difficult to increase productivity. Further, the partially cross-linked butyl rubber cross-linked with peroxide is easily broken. When incorporating the sealing rubber into the aluminum case,
There are things that break.

On the other hand, resin-vulcanized butyl rubber does not have the drawback of being easily cracked. However, this also has a problem in productivity.
General resin vulcanized butyl rubber requires a halogen compound for crosslinking. However, if a halogen compound is present in the sealing rubber, the halogen is liberated and corrodes aluminum. Therefore, the current sealing rubber using resin vulcanized butyl rubber uses a resin vulcanizing agent containing bromine. Bromine compounds are less likely to corrode aluminum than chlorine compounds. But,
The time required for crosslinking increases. This sealing rubber requires a cross-linking time of 1.5 to 2 times that of a general-purpose butyl rubber, and requires secondary cross-linking in order to allow the cross-linking to proceed sufficiently. Therefore, productivity is poor. Also, this sealing rubber may corrode aluminum if it is used at high temperature for a long time.

From the above problems, a sealing rubber made by bonding rubber and plastic has been considered. This is Teflon applied to sulfur-vulcanized butyl rubber.
It is a sealing rubber obtained by adding the properties of Teflon, that is, high heat resistance and impermeability of γ-butyrolactone, to butyl rubber. However, this sealing rubber also has the following problems.

The performance of the aluminum electrolytic capacitor varies. Teflon has no elasticity. If there is a slight burr on the Teflon part of the sealing rubber, there will be a gap between the aluminum case and the Teflon part of the sealing rubber.
A condenser incorporating such a sealing rubber has a γ-
Butyrolactone evaporates quickly. Also, when incorporating the sealing rubber, the hard Teflon part may be wrinkled. This gradually separates the Teflon part and the rubber part. If the Teflon is peeled off, the gas barrier property of the sealing rubber will deteriorate. As described above, when the sealing rubber formed by bonding Teflon is applied, an aluminum electrolytic capacitor having poor performance may be formed.

It is expensive. The material Teflon is expensive and the manufacturing process is complicated. This sealing rubber is about 5 to 7 times more expensive than the sealing rubber using only butyl rubber as a base rubber. 〇 This sealing rubber can only be made in a cylindrical shape. In recent years, a sealing rubber having a shape in which a small cylinder is attached to a circular surface of a sealing rubber has come to be used instead of a simple cylindrical shape. (FIG. 2) This shape is not flat on the circular surface (FIGS. 2 and 5). It is difficult in the manufacturing process to mold Teflon having such a shape one by one and to bond it with rubber.

[0012]

FIG. 2

[0013]

Problems to be solved by the sealing rubber of the present invention will be summarized below. 〇 Withstands long-term use at high temperatures. High heat resistance. It is also a sealing rubber that does not vaporize γ-butyrolactone even when used at high temperatures. Of course, it does not corrode aluminum. 〇 It is cheap. It is a sealing rubber that has a simple manufacturing process and can be mass-produced. Therefore, it is inexpensive. Also, the aluminum electrolytic capacitor provided with this sealing rubber does not cause variations in performance. That is, the rate of rejected products is low. This is also an inexpensive sealing rubber.

There are no restrictions on the shape. One can make the shape of FIG. * The thickness can be reduced. There is a demand for miniaturization of aluminum electrolytic capacitors. The miniaturization of the sealing rubber means miniaturization of the aluminum electrolytic capacitor. For that purpose, it is desirable that the thickness of the sealing rubber can be reduced. Furthermore, the method for easily and inexpensively producing the sealing rubber of the present invention is also provided.

[0015]

MEANS FOR SOLVING THE PROBLEMS The sealing rubber of the present invention is 1
It consists of one or more rubber films and one or more plastic films. The configuration will be described below. (Fig. 1) Select the main base rubber of the rubber part of the sealing rubber. Choose plastic and mold the film. Make one or more rubber and one or more plastic film to make a sealing rubber. Next, this will be described in detail.

[0016]

[Figure 1]

The main base rubber of the rubber portion of the sealing rubber is selected. For the rubber portion of the sealing rubber of the present invention, a rubber that corrodes aluminum and has heat resistance is used. As for heat resistance, the temperature at which continuous use is possible is 100 ° C or higher, preferably 130 ° C.
Select the above rubber. Specific examples of such rubber include silicone rubber, ethylene propylene diene rubber, butyl rubber, hydrogenated acrylonitrile butadiene rubber, and fluorosilicone rubber. Two or more of these may be selected and used together. Other rubbers, for example
Natural rubber, isoprene rubber, styrene-butadiene rubber,
Acrylonitrile-butadiene rubber may be mixed,
Since the heat resistance will be reduced, it should be 20 parts by weight or less. Using this as a base rubber, a compounding agent is added and kneaded. The compounding agent is selected as a suitable sealing rubber.
That is, a substance that corrodes aluminum is not mixed. Table 1 shows examples of formulations suitable for the present invention.

[0018]

[Table 1]

A plastic is selected and a film is molded. For the plastic, select one that has high heat resistance, high gas barrier properties, and does not corrode aluminum. For heat resistance, a softening temperature of 160 ° C. or higher, preferably 200 ° C. or higher is selected. The gas barrier property is selected to be 5 times or more, preferably 100 times or more that of butyl rubber. For example, the permeability of carbon dioxide is 1.0 cc · cm / cm ² · sec ·
Select one with cmHg · 10 ¹⁰ (25 ° C) or less.

Specific examples of such a material include polyvinyl alcohol, ethylene vinyl alcohol copolymer, polyamide, polyimide, polyester, polyvinylidene fluoride and polyether sulfone. A film is molded from these plastics. The thickness of the film is 1 to 200 μm, preferably 10 to 80 μm. The thickness of the film is determined by the gas barrier properties of both the rubber and plastic of choice. For example,
When butyl rubber is selected as the rubber and ethylene vinyl alcohol copolymer is selected as the plastic, both have high gas barrier properties, and therefore the thickness of the ethylene vinyl alcohol copolymer film may be as small as 5 μm. Select silicone rubber with low gas barrier properties as the rubber, and 6-
If nylon is selected, the thickness of the 6-nylon film must be 80-90 μm. The thickness of the film is set according to the material thus selected. You may form a film by mixing two or more types of plastics.

A sealing rubber is made by stacking one or more rubbers and one or more plastic films. The present invention can produce various shapes of sealing rubber. Here, an example of making a cylindrical sealing rubber, which is a simple shape, will be described. (FIG. 1) The sealing rubber of the present invention comprises a rubber compounded and kneaded with and a plastic film selected with. The simplest sealing rubber of the present invention is one in which the rubber kneaded with is molded into a cylindrical shape and the plastic film selected with is applied. However, since the plastic is hard, this sealing rubber has the same drawbacks as the Teflon-sealed sealing rubber described above. That is, the plastic film may be wrinkled or the shape shown in FIG. 2 may not be produced.

Therefore, the plastic film is sandwiched between the rubbers. It is good to put some plastic films between some rubbers. However, it is easy to sandwich one piece of plastic film with two pieces of rubber. The rubber may be cross-linked in advance and a plastic film may be sandwiched therebetween. Alternatively, only the shape may be formed in an uncrosslinked state, and the plastic film may be sandwiched between the two to heat and crosslink. In the former case, the rubber is crosslinked, so the adhesion to the plastic film is not good. In this case, put an adhesive between the rubber and the plastic film. A rubber-based or epoxy-based adhesive is suitable. The latter has relatively good adhesion because the rubber also reacts with the surface of the plastic film when the rubber crosslinks. Also in this case, an adhesive may be used. The type of adhesive is the same. The latter sealing rubber has been devised as a special manufacturing method suitable for it, and will be described below.

The manufacturing method has the following configuration. In order to simplify the explanation, an example of making a sealing rubber having the shape shown in FIG. 1 will be described. I. The kneaded rubber is pressed into a cylindrical mold. (FIG. 3) II. Mold a plastic film. III. A plastic film is put between two cylindrical molds and heated to crosslink the rubber. (FIG. 4) IV. Remove excess plastic film. (FIG. 5) This will be described in detail below.

[0024]

FIG. 3

[0025]

FIG. 4

[0026]

[Figure 5]

I. The kneaded rubber is pressed into a cylindrical mold. As described above, the set compounding agent is added to the rubber suitable for the present invention and kneaded. The kneaded rubber is pressed into a cylindrical mold (FIGS. 3 and 8). At this time, if the convex mold is used instead of the cylindrical mold, the mold shown in FIG. 2 can be manufactured.
The kneaded rubber may be put into the cylindrical mold by any method. It is easy to press-fit with a press using a separately prepared press-fitting die (FIGS. 3 and 6). To the extent that it does not crosslink,
When heated to about 40 to 60 ° C, press-fitting becomes quick. The thickness of the cylindrical mold depends on the number of rubbers used when making the sealing rubber. That is, when the sealing rubber having a thickness of 2 mm is made of two rubbers, the thickness of the mold is 1 mm.

II. Mold a plastic film. As described above, a plastic material suitable for the present invention is selected and a film having a set thickness is molded. This film is cut into the same size as the cylindrical mold.

III. A plastic film is put between two or more cylindrical molds and heated to crosslink the rubber. Place the required number of plastic films between two or more cylindrical molds. (FIG. 4) The number of plastic films, the number of cylindrical molds, and the order of stacking these may be arbitrary. Make sure that the total number of layers is the thickness of the sealing rubber you are going to make.
However, as described above, it is the simplest to sandwich one plastic film between two cylindrical molds, and it is easy to manufacture. Therefore, this will be described as an example.

The plastic film is sandwiched between two molds and placed in another mold for crosslinking. (FIGS. 4 and 10) Lead wire pins are provided in the bridging die. (Fig. 4,
11) This is for making a hole in the sealing rubber through which the lead wire passes. The crosslinking die is heated to crosslink the rubber. Heat under appropriate crosslinking conditions for the rubber of choice. If you choose a plastic that does not easily adhere to rubber, either use an adhesive or pre-treat the plastic film. A rubber-based or epoxy-based adhesive is suitable as the adhesive. This is applied to the rubber part of the cylindrical mold. As a method of surface-treating a plastic film, for example, in the case of a polyvinyl alcohol film, the surface of the film is etched using an alkaline solution such as a 1N sodium hydroxide aqueous solution. A primer for adhesion may be applied to the film in advance.

IV. Remove excess plastic film. After the rubber is crosslinked, it is taken out from the crosslinking mold and the columnar mold is removed. As a result, as shown in FIG. 5, cylindrical rubber is adhered to both sides of the film so as to face each other.
So remove the extra plastic film. For example, the film may be punched with a circular blade having the same diameter as the rubber portion. However, if the film sticks out of the rubber and remains, just like the rubber with Teflon bonded,
There may be burr. The sealing rubber has a diameter of 3 to 20.
Since it has a small size of mm, workability is poor in such a method.

Therefore, the extra plastic film is
It is good to dissolve it and remove it. Select a solvent that dissolves the plastic film well. For example, water is used for polyvinyl alcohol, acetone or dimethylformamide is used for an ethylene vinyl alcohol copolymer, and an aqueous solution of calcium chloride is used for nylon. The film shown in FIG. 5 is immersed in this solvent and left for about 3 minutes to 2 hours to dissolve the film. When the film is dissolved, remove it, wash it lightly with fresh water or solvent and dry it.

[0033]

The sealing rubber of the aluminum electrolytic capacitor of the present invention is a combination of rubber and plastic. Select a material that has high heat resistance and does not corrode aluminum. That is, a material suitable for the sealing rubber of the aluminum electrolytic capacitor is selected. In addition to this, for plastics, we selected materials with high gas barrier properties. The gas barrier property of polyvinyl alcohol is 10 ⁴ times that of butyl rubber in carbon dioxide gas, and 10 ⁵ times that of natural rubber.
However, these plastics are not flexible. Therefore, the plastic alone cannot tightly seal the aluminum electrolytic capacitor. Therefore, the present invention is
A sealing rubber was made by combining a highly flexible rubber and a plastic film having a high gas barrier property. That is,
The rubber portion plays the elasticity of the sealing rubber, and the plastic film plays the gas barrier property of the sealing rubber. Rubber and plastic are selected so that they have heat resistance and do not corrode aluminum. This satisfies all the properties required for the sealing rubber described above.

The manufacturing method of the present invention is a method for easily and surely producing the sealing rubber of the present invention. When the kneaded rubber is put into a press-fitting mold and pressurized, the rubber enters the cylindrical mold through the injection hole (FIGS. 3 and 9). (FIG. 3) Take out the rubber together with the cylindrical mold. Sandwich the plastic film with a cylindrical mold containing rubber. The rubber is crosslinked by placing it in a crosslinking mold and heating it. (Fig. 4) At this time, the hole for the lead wire is a pin for the lead wire of the bridging die (Figs. 4, 11)
Formed by. The cross-linking temperature of rubber is about 130-17
0 ° C. Since the present invention selects a plastic having high heat resistance, the plastic film is not modified when the rubber is crosslinked.

When the rubber is crosslinked, it sometimes reacts with the surface of the plastic film. At this time, the film adheres to the rubber. When not adhering, an adhesive may be used or a plastic film may be surface-treated. After cross-linking, when the cylindrical mold is removed, a cross-linked rubber sticks to both sides of the plastic film. (FIG. 5) The thing of FIG. 5 is immersed in the solvent of a plastic film. Then only the plastic film dissolves. Since the rubber part is crosslinked, it does not dissolve. The solvent described above has a relatively low affinity with rubber. Therefore, unless left in the solvent for a long time, the plastic film between the rubber parts will not dissolve. When the film is dissolved and removed, it can be removed without leaving burrs or the like. In this way, a sealing rubber having no burrs can be produced.

[0036]

EXAMPLES Sealing rubbers of the following Examples A to C were prepared. The size is 8 mm in diameter and 4 mm in height. Example A) Example in which ethylene propylene diene rubber was used as the base rubber of the rubber portion and polyvinyl alcohol was used as the plastic. According to the formulation of Table 1, Example A, the ethylene propylene diene rubber was used as the base rubber and a compounding agent was added and kneading was performed. This is pressed into a cylindrical mold by a press. As the columnar mold, one having a thickness of 2 mm was used, and 20 circular holes having a diameter of 8 mm were hollowed out. When press-fitted with a press, the kneaded rubber enters the hole of the mold. Make two pieces of this mold. Ethylene propylene diene rubber has high heat resistance,
Low gas barrier property. Therefore, polyvinyl alcohol having a high gas barrier property was used for the plastic film. In the case of polyvinyl alcohol, theoretically, a film having a thickness of 1 μm may be used. However, if it is too thin, it is difficult to handle, so a film having a thickness of about 10 μm was molded. The polyvinyl alcohol film is immersed in a 1N sodium hydroxide aqueous solution at about 50 ° C. for 1 minute to etch the surface.

A polyvinyl alcohol film is put between two cylindrical molds. Then, this is placed in a crosslinking mold and heated at 150 ° C. for 10 minutes. When the ethylene propylene diene rubber is crosslinked, the rubber is taken out together with the cylindrical mold, and the cylindrical mold is removed. As a result, a crosslinked ethylene propylene diene rubber sticks to both sides of the polyvinyl alcohol film. Put this in water as it is. Take it out of the water after about 5 minutes,
The polyvinyl alcohol film is melted into individual sealing rubbers.

Example B) Example in which silicone rubber is used as the base rubber of the rubber portion and nylon is used as the plastic. The silicone rubber is SH-8 from Toray Dow Corning Co., Ltd.
81 U was used. A peroxide is added to this, and it is pressed into a cylindrical mold by a press. The same cylindrical mold as in Example A was used. Silicone rubber has high heat resistance but very low gas barrier property. Therefore, nylon having a relatively high gas barrier property was used for the plastic film. 6 for nylon
-Nylon was selected and a film having a thickness of 80 µm was formed. The film was coated with a primer.

A nylon film is put between two cylindrical molds. Put this in the mold for crosslinking,
Heat for minutes. During this time, the silicone rubber crosslinks. Take this out, and also remove the cylindrical mold. Then, the cross-linked silicone rubber sticks to both sides of the nylon film. As it is, it is immersed in a saturated calcium chloride aqueous solution and left for about 30 minutes. The nylon film melts and becomes a sealing rubber one by one.

Example C) Example in which partially cross-linked butyl rubber is used for the rubber part and ethylene vinyl alcohol copolymer is used for the plastic. According to the formulation of Table 1, Example C, a compounding agent is added using the partially cross-linked butyl rubber as the base rubber and kneading is performed. This is pressed into a cylindrical mold by a press. The same cylindrical mold as in Example A was used. Butyl rubber has a high gas barrier property and also has heat resistance. Furthermore, by putting an ethylene vinyl alcohol copolymer film in it, the gas barrier property can be further enhanced. The ethylene vinyl alcohol copolymer film was molded to have a thickness of 10 μm. The ethylene vinyl alcohol copolymer film has a temperature of 1 ° C at 50 ° C.
The surface is etched by immersing in a specified aqueous sodium hydroxide solution for 1 minute.

An ethylene vinyl alcohol copolymer film is sandwiched between two cylindrical molds. This is put into a crosslinking mold and heated at 170 ° C. for 10 minutes. Butyl rubber crosslinks during this time. This is taken out and the cylindrical mold is removed. As a result, a crosslinked butyl rubber is adhered to both sides of the ethylene vinyl alcohol copolymer film. This is immersed in acetone as it is. About 3
After 0 minutes, the ethylene vinyl alcohol copolymer film was melted to form a sealing rubber.

In this example, since the cylindrical mold used in Examples A and B was used, the sealing rubber had the same thickness as Examples A and B. However, this example is a combination of a butyl rubber having a high gas barrier property among rubbers and an ethylene vinyl alcohol copolymer having a high gas barrier property among plastics. Therefore, even if the thickness of the rubber portion is reduced to half, a sealing rubber having a gas barrier property equal to or higher than that of the conventional sealing rubber using butyl rubber can be produced. If the rubber part is thin, the productivity will not decrease even if partially cross-linked butyl rubber with poor flow is used. Further, there is no problem of cracking when incorporated in an aluminum electrolytic capacitor. still,
By thinning the sealing rubber, the aluminum electrolytic capacitor can be downsized.

(Experiment) The rubber stoppers of Examples A to C were tested for gas barrier properties and heat resistance. 1.0 ml of γ-butyrolactone is put into a glass tube having a diameter of 7.5 mm. Example A
~ Close the glass tube mouth tightly with the sealing rubber from Example C,
Leave at 120 ° C. The sealing rubber is observed after 7 days and 30 days, and the glass tube provided with the sealing rubber is weighed. As a control, a sealing rubber obtained by partially crosslinking butyl rubber with peroxide was used. This is the sealing rubber currently applied to aluminum electrolytic capacitors.

The results are shown in Table 2. The weight reduction of the glass tube provided with the sealing rubber of Examples A to C was largest in the sealing rubber of the partially crosslinked butyl rubber, and then in the order of Example B, Example A and Example C. Thus, the gas barrier property of the sealing rubber of the present invention was superior to that of the current product. Especially, the gas barrier property of the sealing rubber of Example C in which butyl rubber and ethylene vinyl alcohol copolymer film were combined was high. In addition, none of the sealing rubbers, including the control, were hard or conversely sticky. Therefore, it can be said that each of the sealing rubbers of the present invention has heat resistance equivalent to that of the existing sealing rubbers. From the results of this experiment, it can be said that the sealing rubbers of Examples A to C are very high in heat resistance and gas barrier property and can be used in cars and computers.

[0045]

[Effect] The sealing rubber of the present invention is a combination of rubber and a plastic film. According to the present invention, it is possible to provide a sealing rubber having heat resistance equal to or higher than that of the conventional sealing rubber and having a high gas barrier property which is not present in the conventional sealing rubber. Above all, when silicone rubber is used for the rubber portion, since the silicone rubber has extremely high heat resistance, a sealing rubber having particularly high heat resistance can be produced. This sealing rubber can withstand continuous use at 150 ° C. and is a sealing rubber that has never existed before.

If the manufacturing method of the present invention is adopted, it can be manufactured easily and can be mass-produced. The material used is cheaper than Teflon, and it is possible to provide inexpensive sealing rubber. Moreover, if this method is adopted, there is almost no variation in the product. That is,
It overcomes the problems of the sealing rubber with Teflon glued together (Teflon becomes a burr and the aluminum case cannot be sealed tightly).

Furthermore, since the sealing rubber of the present invention is made by molding rubber, it can be made in any shape. In addition, since a plastic film having a gas barrier property much higher than that of rubber is used, even if the thickness of the sealing rubber is reduced to ½ to ⅓ of the conventional sealing rubber, γ-
Prevents volatilization of butyrolactone. By incorporating this sealing rubber, the aluminum electrolytic capacitor can be downsized.

[Brief description of drawings]

FIG. 1 is a sectional view of a sealing rubber of the present invention.

FIG. 2 is a cross-sectional view of a sealing rubber in which a small cylinder is attached to a circular surface of the sealing rubber.

FIG. 3 is a cross-sectional view when the kneaded rubber is poured into a columnar mold using a press-fitting mold.

[Fig. 4] Insert a plastic film with a cylindrical mold,
It is a sectional view when it puts in a bridge mold.

FIG. 5: After cross-linking the rubber, take it out from the mold for cross-linking,
It is sectional drawing when a cylindrical mold is also removed.

[Explanation of symbols]

 1 Rubber 2 Plastic Film 3 Hole for Lead Wire 4 Aluminum Case 5 Circular Surface 6 Press-fitting Mold 7 Kneaded Rubber 8 Cylindrical Mold 9 Injection Hole 10 Cross-linking Mold 11 Lead Wire Pin 12 Where to Cut the Film

[Table 2]

Claims (3)

[Claims] 1. A plastic having a softening temperature of 160 ° C. or higher, a high gas barrier property and not corroding aluminum is formed into a film having a thickness of 1 to 200 μm, and this plastic film and a temperature at which continuous use is possible are 100.
Rubber that is above ℃ and does not corrode aluminum,
Sealing rubber for aluminum electrolytic capacitors characterized by being laminated. 2. A sealing cap for an aluminum electrolytic capacitor, characterized in that the rubber is superposed on the plastic film in an uncrosslinked state, and this is heated to crosslink the rubber and simultaneously bring the rubber and the plastic into close contact with each other. Rubber manufacturing method. 3. The method according to claim 2, wherein after the rubber is crosslinked, the plastic film protruding from the rubber is removed by dissolving the plastic film in water or / and a solvent. The method for producing a sealing rubber for an aluminum electrolytic capacitor according to claim 2.