JPH02194517A - Sealing member for electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To be more resistant to an organic solvent and to enhance an airtight property by a method wherein a copolymer polymer which is composed of isoprene, isobutylene and divinylbenzene and with which a unique additive is mixed is used as a rubber sheet and a bakelite sheet and the copolymer polymer are united by laying an EPDM sheet or an IIR sheet between them. CONSTITUTION:An additive selected from a group composed of an organic peroxide, a carbon filler and a metal oxide is mixed with a copolymer polymer which is composed of isoprene, isobutylene and divinylbenzene; an unvulcanized or semivulcanized rubber sheet 4 is prepared; an EPDM sheet or an IIR rubber sheet 6 belonging to a resin vulcanization system is piled up on the rubber sheet; in addition, an unhardened or semihardened phenolic (epoxy) bakelite sheet 5 is piled up; they are molded collectively under a molten bonding condi tion. A sealing member 3 molded in this manner is less permeable to a gas, is hardly swollen and is highly resistant to an organic solvent; paste is detached at a low rate; accordingly, long service life can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a sealing body for an electrolytic capacitor, and more particularly, to a sealing body for an electrolytic capacitor that exhibits high organic solvent resistance and excellent airtightness. and its manufacturing method.

[Prior art] Electrolytic capacitors are small, large capacitors, inexpensive, and exhibit excellent characteristics such as smoothing rectified output, and are one of the important components of various electrical and electronic devices. An element consisting of an aluminum film that has been oxidized to a dielectric oxide film is used as an anode, and a collector cathode is impregnated with an electrolytic solution (paste), which is then sealed in a container.

Since electrolytic capacitors are used while performing a chemical reaction to regenerate the oxide film, their characteristics are most dependent on the properties of the electrolyte used. The electrolyte for electrolytic capacitors is generally made of ethylene glycol and boric acid. Recently, non-aqueous electrolytes containing substantially no water have been increasingly used to avoid problems such as deterioration and poor appearance of capacitors due to water gasification during high-temperature use.

A container that encloses an element impregnated with an electrolytic solution is composed of a case made of a metal material such as aluminum and having an opening at one end, and a sealing body mainly made of Bakelite as a base material. Bakelite is most commonly used as the base material for the sealing body from the viewpoints of structure retention properties, cost, etc.

During manufacture, an electrolytic capacitor product is assembled by placing an element impregnated with an electrolytic solution in a case, and then fitting a sealing member into the opening of the case. To ensure this fit,
A rubber sheet or the like is often interposed between the Bakelite base material and the opening.

In order to improve the performance of electrolytic capacitors and expand their use, it is necessary to actively promote the use of non-aqueous electrolytes as described above, but this type of electrolyte does not use Bakelite, which is the base material for the sealing body. They have a strong tendency to dissolve and corrode, and even if the characteristics can be improved by improving the electrolyte, from the perspective of the overall performance of capacitor products, it is inevitable that the life characteristics will deteriorate due to the deterioration of the sealing body. .

Attempts have been made to improve electrolytic capacitor sealing bodies to expand the range of electrolytes that can be used. If S,
Special Publication No. 57-38182 describes a vulcanized rubber sheet and
It is characterized by the use of a sealing plate formed by bonding a filler-filled polypropylene plate containing a filler such as talc by thermocompression bonding with a polyolefin hot melt film mainly composed of polypropylene or polyethylene interposed. An electrolytic capacitor is disclosed.

In addition, from column 2, line 34 to line 3B, line 4 of the same publication, it is stated that although butyl rubber (FIR) is the most stable material, there is a concern that it may contain corrosive extractables, so it is used for electrolytic capacitors. It is stated that practical use as a sealing material has not progressed much. For this reason, in this technology, in order to achieve the objective, studies are being conducted to obtain a sealing plate that does not corrode by using ethylene propylene terpolymer (EPT) as the next best material.

However, in the case of EPT-covered baking, unlike butyl rubber-covered baking, it has relatively high gas permeability, resulting in large paste dropouts, and the possibility of corrosion, etc. occurring cannot be denied due to the large swelling property of organic solvents. Also, -
However, sulfur-free, quinoid-based vulcanization systems have poor adhesion to phenol, making it difficult to produce highly airtight products.

In order to obtain a suitable sealing body for electrolytic capacitors with a wide range of applications, it is necessary to improve the organic solvent resistance, fitability, and
In addition, it is necessary to comprehensively consider the adhesion to the baking board.

[Problems to be Solved by the Invention] EPT is not necessarily sufficient as a material for the rubber sheet interposed when producing a sealing body for electrolytic capacitors in terms of gas permeability and organic solvent resistance. In the sealing body for an electrolytic capacitor used, dissipation due to gasification and permeation of the non-aqueous electrolyte, swelling deterioration due to permeation, etc. are unavoidable.

Furthermore, in order to obtain a more suitable electrolytic capacitor, we found that it would be best to not only improve the materials used, but also make structural improvements that would ensure more secure fitting with the capacitor case. .

Therefore, the present invention uses a rubber sheet that is made of a material that has less gas permeation than EPT and is less likely to swell, has excellent fit to the capacitor outer case, and has good adhesion to the bake plate, and also improves the structure of the sealing body. By doing so, it is an object of the present invention to obtain a sealing body for electrolytic capacitors which is highly resistant to organic solvents, has excellent airtightness, and is suitable for a wide range of applications.

[Means for Solving the Problems] According to the present invention, a rubber sheet made of an uncured or semi-vulcanized copolymer consisting of isoprene, inbutylene, and divinylbenzene and mixed with an additive, and an uncured or semi-cured copolymer polymer are provided. A sealing body for an electrolytic capacitor integrally formed with a phenol (epoxy) bake plate, wherein the additive is selected from the group consisting of an organic peroxide, a carbon filler, and a metal oxide, and the rubber sheet and the bake plate are integrally formed. There is provided a sealing body for an electrolytic capacitor characterized by interposing an EPDM sheet between the plate and the plate.

It is preferred if the EPDM sheet contains additives selected from the group consisting of vulcanizing agents, carbon fillers and metal oxides. The vulcanizing agent can be, for example, 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, which is preferably incorporated in an amount of 1 to 6 parts by weight. For example, an electrolytic rubber sheet made of an uncured or semi-vulcanized copolymer made of isoprene, isobutylene, and divinylbenzene and mixed with additives and an uncured or semi-cured phenol (epoxy) bake plate are integrally formed. A sealing body for a capacitor, wherein the additive is selected from the group consisting of an organic peroxide, a carbon filler, and a metal oxide, and an IrR rubber belonging to a resin vulcanization system is provided between the rubber sheet and the bake plate. A sealing body for an electrolytic capacitor characterized by interposing a sheet is provided.

It is preferable that the 11R rubber sheet belongs to a resin vulcanization system using an alkylphenol formaldehyde resin as a vulcanizing agent.

Unvulcanized copolymer polymers of isoprene, isobutylene, and divinylbenzene are commercially available, and by mixing a predetermined amount of additives as vulcanizing agents, unvulcanized or semi-vulcanized copolymer polymers are prepared using conventional methods. Prepare. The conditions for vulcanization are:
Pressure 30 kg/aA~200kz/cd, temperature 1
The temperature is 30°C to 200°C.

The rubber sheet interposed between the Bakelite base material and the case opening may be unvulcanized6, but it is better to use a rubber sheet that has increased elasticity and improved adhesion through vulcanization to ensure secure fit. In addition, organic peroxides,
Vulcanization with additives selected from the group consisting of carbon fillers and metal oxides can improve adhesion to Bakelite substrates. however,
Depending on the vulcanization system and the type of compounding agents, organic solvent resistance may deteriorate, so the degree of vulcanization of the copolymer using the above additives should be determined by comprehensively taking these factors into consideration when manufacturing electrolytic capacitors. , should be determined according to the purpose.

Further in accordance with the present invention, a copolymer of isoprene, isobutylene, and divinylbenzene is mixed with an additive selected from the group consisting of organic peroxides, carbon fillers, and metal oxides, and then unvulcanized. An electrolytic method characterized by preparing a semi-vulcanized rubber sheet, overlaying an EPDM sheet on this rubber sheet, further overlaying an uncured or semi-cured phenol (epoxy) bake plate, and integrally molding under fusion conditions. A method of manufacturing a capacitor sealing body is provided.

A suitable manufacturing method may be provided if the EPDM sheet contains additives selected from the group consisting of vulcanizing agents, carbon fillers and metal oxides.

When stacking E PDM sheets, the thickness is 0.
Smooth progress of integral molding can be achieved by stacking solid sheets of 1111 m to 2 sheets, or by dissolving them in an organic solvent and layering them to make the stack uniform. Suitable organic solvents include, for example, toluene, tetrahydrofuran.

By integrally molding under the fusion conditions of a pressure of 30 kg/cxA to 200 kg/cJ and a temperature of 130°C to 200°C, a suitable sealing body for an electrolytic capacitor is manufactured using an interposed EPDM sheet. be able to.

Further in accordance with the invention, additives selected from the group consisting of organic peroxides, carbon fillers and metal oxides are incorporated into the copolymer polymer consisting of isoprene, isobutynone and divinylbenzene. + m of an uncured or semi-vulcanized rubber sheet, overlaying this rubber sheet with an IIR rubber sheet belonging to a resin vulcanization system, and further overlapping an uncured or semi-cured phenol (epoxy) bake plate, and adjusting the fusion conditions. Provided is a method for manufacturing a sealing body for an electrolytic capacitor, characterized in that the sealing body is integrally molded at the bottom.

A suitable manufacturing method can be provided if the JNR rubber sheet belongs to a resin vulcanization system using an alkylphenol formaldehyde resin as a vulcanizing agent.

When stacking the FIR rubber sheets, the thickness is 0.1n.
un~2 m! Smooth progress of integral molding can be achieved by stacking n solid sheets, or by dissolving them in an organic solvent and layering them to make the stacking uniform. Suitable organic solvents include, for example, toluene, tetrahydrofuran.

Pressure 30kg/ad~200kr/cd, temperature 130℃
If integrally molded under fusion bonding conditions of ~200''C, a suitable sealing body for an electrolytic capacitor can be manufactured using an interposed IrR rubber sheet.

In addition, when using dimethylformamide-based or γ-butyrolactone-based pastes with high solubility, there is a risk that impurities may be extracted from the phenol (epoxy) baking board, so the outer surface of the phenol (epoxy) baking board should be coated with polypropylene or A thin film sheet made of butyl rubber or the like may be attached.

The unique copolymer disclosed by the present invention has low gas permeability and less paste shedding, and has lower solvent affinity than EPT and is less likely to swell, so it is superior in terms of organic solvent resistance and structure retention ability. It is an extremely excellent material in itself. Copolymers such as EPT have poor organic solvent resistance and a large amount of gas permeation, making it relatively difficult to produce highly airtight products. By applying a polymer to the surface of the EPT, organic solvents passing through the EPT can be blocked.

The present invention provides a good thermal stability for this copolymer by using an additive selected from the group consisting of organic peroxides, carbon fillers, and metal oxides as a vulcanizing agent. The purpose is to improve the fitability of the sealing body to the case while strengthening the properties without impairing them.

The sealing body for an electrolytic capacitor according to the present invention is a bake plate, an E
It has a three-layer structure consisting of a PDM sheet or FIR sheet and a specific copolymer, but when integrally molded, these three are fused together via a thin center EPDM sheet or IR sheet, creating a clear boundary. It is estimated that the structure has no structure in which the constituent components change continuously. These differ from each other in terms of hardness, which is an important element that provides good fit to the sealing body, and by integrating them, it is possible to achieve effects that cannot be obtained with either one or a combination of the two. Can be done.

[Effects of the Invention] According to the present invention, a copolymer made of isoprene, imbutylene, and divinylbenzene and mixed with unique additives is used, and EPDM is used between the baking plate and the copolymer. 4. According to the present invention, by interposing and integrating a sheet or an IIR sheet, a rubber-covered baked sealing body for an electrolytic capacitor is provided which has high organic solvent resistance, low gas permeability, and little paste release. Sealing bodies for electrolytic capacitors have lower gas permeability than EPT, are less susceptible to swelling, and have higher resistance to organic solvents, so they contain organic solvents such as γ-butyrolactone (8m>) and dimethylformamide (DMF) as components of the electrolyte. Because there is less paste coming out than Mana EPT tension bake,
Longer life can be achieved.

[Example] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples.

Using a vulcanized copolymer polymer or an unvulcanized to semi-vulcanized copolymer polymer, the following rubber compounding ratio (parts by weight, phr) was used:
Mix raw materials according to

Unvulcanized to semi-vulcanized isobutylene isopropylene divinylbenzene copolymer SRF carbon hard clay stearic acid 3 ZnO3 dicumyl peroxide 2 The raw materials blended according to the above recipe were mixed and processed according to a conventional method to a thickness of 1.5 mm. Make a rubber sheet.

An EPDM sheet of I7 0°3 am (Example 1) was placed between the copolymer rubber sheet prepared as described above and an uncured or semi-cured phenol (epoxy) baking plate. or ■ Interposing an IR rubber sheet (Example 2),
In the next step (h), they were laminated together under bonding conditions and integrally molded to produce a sealing body for an electrolytic capacitor.

Temperature: 165°C Time: 10 minutes Pressure: 750 kg/d The EPDM sheet is an unvulcanized or semi-vulcanized sheet containing 2 parts by weight of 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexene. It was made into an EPDM sheet.

In addition, the IIR rubber sheet should be made from the following composition.

frRio.

SRF Carbon 50 Hard Clay 100 Stearic Acid
3 ZnO10 Alkylphenol formaldehyde resin 13 Tetrabutylthiuram disulfide 4 Cellular condensate
= 1 An electrolytic capacitor equipped with a sealing body according to Example 1, an electrolytic capacitor equipped with a sealing body according to Example 2, and a conventional electrolytic capacitor (Comparative Example 1) using EPT having the same thickness as a sealing body. Created. Using a γ-butyrolactone electrolyte as a paste, an electrolytic capacitor having a size of 20φ×40mm, a rating of 63 WV, and 82OμF was produced by a conventional method.

Figure 1 shows a sectional view of an electrolytic capacitor, and Figure 2 shows a sectional view of a sealing body for an electrolytic capacitor according to the present invention.
2 is an element, 2 is a case, 3 is a sealing body, 4 is a copolymer sheet, 5 is a plate, 6 is an EPDM sheet or an IIR rubber sheet, and 7 is a terminal.

1 Prison j Regarding the electrolytic capacitor equipped with the sealing body according to Example 1, the electrolytic capacitor equipped with the sealing body according to Example 2, and the conventional electrolytic capacitor using EPT of the same thickness as the sealing body (Comparative Example 1), Paste removal, changes in capacitance (Cap), and changes in dielectric loss tangent (tan δ) due to long-term use at high temperatures were measured.

The paste removal test results are shown below.

Example 1 -3.8■ 4.

Example 2-2.3■ Comparative Example 1 -24°3■ Changes in capacitance and dielectric loss tangent were measured over time. The test results for the electrolytic capacitor equipped with the sealing body according to Example 1 are shown in FIG. 3, and the test results for the electrolytic capacitor equipped with the sealing body according to Example 2 are shown in FIG.
Further, test results for a conventional electrolytic capacitor (Comparative Example 1) are also shown in FIGS. 3 and 4.

From the above results, the sealing body for electrolytic capacitors according to the present invention shows that when an organic abrasion such as γ-butyrolactone is used as a component of the electrolyte, there is less paste coming out compared to EPT pasting and baking, and the performance is improved and the life is extended. It turns out that it is possible to achieve this.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an electrolytic capacitor, Fig. 2 is a sectional view of a sealing body for an electrolytic capacitor according to the present invention, and Fig. 3 is a sectional view of Example 1.
FIG. 4 is a diagram showing test results for an electrolytic capacitor equipped with a sealing body according to Example 2, and FIG. 4 is a diagram showing test results for an electrolytic capacitor equipped with a sealing body according to Example 2. 1... Cord 2... Case 3... Sealing body 4... Copolymer sheet 5... Baking plate 6... BPDM sheet or IIR rubber sheet 7...
・Terminal FIG. FIG. G. FIG.

Claims (8)

[Claims] (1) Electrolytic molding of a rubber sheet made of an unvulcanized or semi-vulcanized copolymer made of isoprene, isobutylene, and divinylbenzene and mixed with additives, and an uncured or semi-cured phenol (epoxy) bake plate. A sealing body for a capacitor, wherein the additive is selected from the group consisting of an organic peroxide, a carbon filler, and a metal oxide, and an EPDM sheet is interposed between the rubber sheet and the bake plate. Features a sealing body for electrolytic capacitors. (2) A rubber sheet made of an uncured or semi-vulcanized copolymer made of isoprene, isobutylene, and divinylbenzene and mixed with additives, and an uncured or semi-cured phenol (epoxy) bake plate are integrally molded. A sealing body for an electrolytic capacitor, wherein the additive is selected from the group consisting of an organic peroxide, a carbon filler, and a metal oxide, and an IIR member belonging to a resin vulcanization system is provided between the rubber sheet and the bake plate. A sealing body for an electrolytic capacitor characterized by interposing a rubber sheet. (3) The sealing body for an electrolytic capacitor according to claim 2, wherein the IIR rubber sheet belongs to a resin vulcanization system using an alkylphenol formaldehyde resin as a vulcanizing agent. (4) A copolymer consisting of isoprene, isobutylene, and divinylbenzene is mixed with an additive selected from the group consisting of organic peroxides, carbon fillers, and metal oxides, and is then unvulcanized or semi-vulcanized. A sealing body for an electrolytic capacitor, characterized in that a rubber sheet is prepared, an EPDM sheet is layered on the rubber sheet, an uncured or semi-cured phenol (epoxy) bake plate is further layered, and the sealing body is integrally formed under fusion conditions. manufacturing method. (5) The method for producing a sealing body for an electrolytic capacitor according to claim 4, wherein when stacking the EPDM sheets, the EPDM sheets are stacked after being dissolved in an organic solvent. (6) A copolymer consisting of isoprene, isobutylene, and divinylbenzene is mixed with an additive selected from the group consisting of organic peroxides, carbon fillers, and metal oxides, and is then unvulcanized or semi-vulcanized. A rubber sheet of
A method for manufacturing a sealing body for an electrolytic capacitor, which is characterized by stacking baking sheets (epoxy) and integrally molding them under fusion conditions. (7) The method for producing a sealing body for an electrolytic capacitor according to claim 6, wherein the IIR rubber sheet belongs to a resin vulcanization system using an alkylphenol formaldehyde resin as a vulcanizing agent. (8) The method for producing a sealing body for an electrolytic capacitor according to claim 6 or 7, wherein the IIR rubber sheets are dissolved in an organic solvent and then stacked.