JPH02194515A - Sealing member for electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To be more resistant to an organic solvent, to enhance an airtight property and to prevent a paste from being detached by a method wherein an IIR which uses an alkyl phenol formaldehyde resin as a vulcanizing agent is used and a bakelite sheet and an IIR are united by laying an EPDM between them. CONSTITUTION:A nonvulcanized or semivulcanized EPDM sheet 6 to which a vulcanizing agent has been mixed is piled up on an unvulcanized or semivulcanized IIR rubber sheet 4 belonging to a resin vulcanization system which uses an alkyl phenol formaldehyde resin as a vulcanizing agent; in addition, an unhardened or semihardened phenolic (epoxy) bakelite sheet 5 is piled up; they are molded collectively under a molten bonding condition. During this process, when they are bonded collectively under the molten bonding condition at a pressure of 30 to 200kg/cm<2> and at a temperature of 130 to 200 deg.C, it is possible to obtain a suitable sealing member 3 for electrolytic capacitor use. The sealing member for electrolytic capacitor use is less permeable to a gas than an EPT, is hardly swollen and is highly resistant to an organic solvent. A paste is detached at a rate lower than an EPT-pasted bakelite sheet; accordingly, long service life can be realized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the improvement of a piercing body for electrolytic capacitors, and more specifically, to the improvement of a piercing body for electrolytic capacitors that has high organic solvent resistance and poor airtightness. The present invention relates to a sealing body and a method for manufacturing the same.

[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 greatly depend on the properties of the electrolyte used. The electrolyte for electrolytic capacitors is generally made of ethylene glycol and boric acid. Recently, non-aqueous electrolytic solutions that do not contain substantially water have been increasingly used because of problems such as deterioration and poor appearance of capacitors due to water gasification during high-temperature use.

A container for enclosing an element impregnated with an electrolytic solution is composed of a case having an opening at -Ii and made of a metal material such as aluminum, 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 manufacturing, an electrolytic capacitor product is assembled by placing an element impregnated with an electrolyte into a case, and then fitting and sealing a sealing member into the opening of the case. In order to ensure this fitting, rubber seals 1 to 1 are 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 promote the active use of non-aqueous electrolytes as described above, but this type of electrolyte does not use Bakelite, which is the base material of 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 seals to expand the range of electrolytes that can be used.For example,
Special Publication No. 57-38182 describes a vulcanized rubber sheet and
The sealing plate is made by joining a filler-filled polypropylene plate containing filler such as talc with a polyolefin hot-melt film containing polypropylene or polyethylene as the main component, by thermocompression bonding. An electrolytic capacitor with characteristics is disclosed.

In addition, from line 34 of column 3 to line 4 of column 3 of the same publication, it is stated that although butyl rubber (IIR) is stable as a material, there is a concern that it may release corrosive extractables, so it is It is stated that practical use as a sealing material has not progressed very far. In order to achieve this goal, this technology is conducting studies to obtain a sealing plate that does not corrode by using ethylene propylene terpolymer (BPT) as the next best material.

However, in the case of BPT-lined baking, unlike butyl rubber-lined baking, it has a relatively high gas permeability, so paste removal is large, and the possibility of corrosion etc. occurring cannot be denied because it is highly swellable with organic solvents.

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] Butyl rubber (IIR) is extremely stable as a sealing material.
As a result of repeated studies to realize a truly effective sealing body for electrolytic capacitors using this method, we found that the most problematic point when applying this to a sealing body was the release of the corrosive extractables mentioned above. However, it is difficult to create a sealing body with high airtightness due to poor adhesion to Bakelite, which is a phenolic resin, when using vulcanization systems such as sulfur, sulfur-free, and quinoid vulcanization systems. It turned out to be a point. Vulcanization of butyl rubber involves resin vulcanization using a metal halide or chlorinated polymer as a catalyst, but this type of vulcanization also causes problems such as corrosion, so it is not suitable for sealing bodies for electrolytic capacitors. It is not possible to obtain properly matched rubber sheets.

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 to make structural improvements that would ensure more secure fitting with the capacitor case. .

Therefore, in the present invention, the alkylphenol formaldehyde resin is used alone and vulcanized at high temperature for a long time, or the alkylphenol formaldehyde resin is treated with a small amount of thiuram-based vulcanization or an acidic catalyst such as p-toluenesulfonic acid. By using IIR and structurally improving the sealing body, it has high organic solvent resistance.
To provide a rubber-covered baked sealing body for an electrolytic capacitor that has high airtightness and less paste leakage.

[Means for Solving the Problems] According to the present invention, an electrolytic capacitor is provided in which an unvulcanized or semi-vulcanized I-R rubber sheet and an uncured or semi-cured phenol (epoxy) bake plate are integrally molded. The IIR rubber sheet belongs to a resin vulcanization system using an alkylphenol formaldehyde resin as a vulcanizing agent, and the IIR
There is provided a sealing body for an electrolytic capacitor, characterized in that an unvulcanized or semi-vulcanized EPDM sheet mixed with a vulcanizing agent is interposed between a rubber sheet and the bake plate.

flR is sold as an unvulcanized polymer, and a predetermined amount of alkylphenol formaldehyde resin is mixed therein as a vulcanizing agent, and unvulcanized or semi-vulcanized II [
Prepare.

The amount of alkylphenol formaldehyde resin mixed is preferably 5 to 20 parts by weight. The conditions for vulcanization are a pressure of 30ksr/a+1 to 200kg/aa and a temperature of 130°C to 200'C.

I interposed between the Bakelite base material and the case opening
The IR rubber sheet may be an unvulcanized one, but it is preferable to use one whose elasticity increases through vulcanization and improves adhesion from the viewpoint of ensuring secure fitting.
Generally, vulcanization causes a decrease in organic solvent resistance, so IIR using alkylphenol formaldehyde resin
The degree of vulcanization of the rubber sheet should be determined in accordance with the use and purpose of the electrolytic capacitor manufactured by comprehensively considering these factors.

The vulcanizing agent to be mixed with the unvulcanized or semi-vulcanized EPDM sheet interposed between the IIR rubber sheet and the baking plate is, for example, 1.1-di(1-butylperoxy)-3,3,5-
It can be trimethylcyclohexane and is preferably incorporated in an amount of 1 to 6 parts by weight.

Furthermore, according to the present invention, an unvulcanized or semi-vulcanized IIR rubber sheet that belongs to a resin vulcanization system that uses an alkylphenol formaldehyde resin as a vulcanizing agent is mixed with an unvulcanized or semi-vulcanized rubber sheet that is mixed with a vulcanizing agent. A method for producing a sealing body for an electrolytic capacitor is provided, which comprises stacking BPDM sheets, further stacking an uncured or semi-cured phenol (epoxy) bake plate, and integrally molding the sheets under fusion conditions.

When stacking unvulcanized or semi-vulcanized EPDM sheets mixed with a vulcanizing agent, these can be stacked as solid sheets with a thickness of 0°1 to 2 cm, or they can be layered after being dissolved in an organic solvent. By making it uniform, the integral molding can proceed smoothly. Suitable organic solvents include, for example, toluene, tetrahydrofuran, and the like.

A suitable sealing body for an electrolytic capacitor can be obtained by integral molding under fusion conditions of a pressure of 30 kcr/aa to 200 kg/d and a temperature of 130 to 200°C.

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

[Effect]

IIR is an excellent material in itself in terms of low gas permeability, little paste shedding, resistance to swelling, organic solvent resistance, and structure retention ability, but as mentioned above, it It was difficult to make a product with poor adhesion and high airtightness.The present invention uses an alkylphenol formaldehyde resin as a vulcanizing agent for IIR, and also interposes an EPDM sheet between the bake plate and the IIR sheet. This solves the problem of adhesiveness! ! : At the same time, it provides better fitting performance.

The seal for electrolytic capacitors according to the present invention is made of a baked plate, E
It has a three-layer structure consisting of a PDM sheet and IIR, but during integral molding, these three are fused together via a thin EPDM sheet, creating a structure with clear boundaries in which the constituent components change continuously. It is estimated that These differ from each other in terms of hardness, which is an important element that gives good fit to the sealing body (-f), and by integrating them, effects that cannot be obtained by combining them or any two of them can be obtained. can be realized.

[Effects of the Invention] According to the present invention, organic solvent resistance is achieved by using IIR using an alkylphenol formaldehyde resin as a vulcanizing agent and by interposing and integrating EPDM between the bake plate and the IIR sheet. high airtightness,
The sealing body for electrolytic capacitors according to the present invention is a rubber-coated baked sealing body with less paste coming out.The sealing body for electrolytic capacitors according to the present invention has lower gas permeability than EPT, is less swollen, and has high organic solvent resistance. γ-butyrolactone (BL) and dimethylformamide (DMF) are components of
), etc. can be used, and since there is less base I removal than with EPT baking, a longer life can be achieved.

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

Using unvulcanized to semi-vulcanized IIR, raw materials were compounded at the following rubber compounding ratio (parts by weight, phr).

Marukyu unvulcanized to semi-vulcanized IIR100 SRF carbon 50 hard clay 100 stearin
3 ZnOtO Alkylphenol formaldehyde resin 13 Tetrabutylthiuram disulfide 4 The raw materials formulated according to the above recipe were mixed and processed according to a conventional method to a thickness of 1.
A rubber sheet of No. 5- was produced.

Nirako ■(@) 1,1-di(t-butyl Unvulcanized to semi-vulcanized E with a thickness of 0.3+nn mixed with 2 parts by weight of (peroxy)-3,3,5-trimethylcyclohexene
A PDM sheet was interposed therebetween, the sheets were laminated together under the following fusion conditions, and integrally molded to produce a sealing body for an electrolytic capacitor.

Temperature: 180° C. Time: 20 minutes Pressure: 120 kg 10 & Preparation of Electrolytic Capacitors An electrolytic capacitor equipped with the sealing body according to Example 1 and a conventional electrolytic capacitor (Comparative Example 1) using EPT of the same thickness as the sealing body were manufactured. Using a γ-butyrolactone electrolyte as a paste, size and
An electrolytic capacitor of 20φ×401 with a rating of 63WV and 820 μF was manufactured.

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 an FIR rubber sheet, 5 is a baking plate, 6 is an EPDM sheet, and 7 is a terminal.

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

Paste removal test results The paste removal test results are shown below as weight changes after 100 hours of use at 110°C.

Example 1 -3.6 ■ Comparative Example 1 -24.3 ■ Appearance and 8j'' test results Using an electrolytic capacitor for a long time at 110°C, changes in capacitance and dielectric loss tangent were measured over time. The test results for the electrolytic capacitor without the sealing body according to Example 1 are shown in FIG. 3, and the test results for the conventional electrolytic capacitor (Comparative Example 1) are also shown in FIG.

From the above results, when the material body for electrolytic capacitors according to the present invention uses an organic solvent 1 such as γ-butyrolactone as a component of the electrolytic solution, paste removal is less than that of EPT pasted baking, the performance is improved, and the length becomes white. 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 diagram showing test results for an electrolytic capacitor equipped with a sealing body according to Example 1. . 1...Element 2...Case 3...Sealing body 4...ITR rubber sheet 5...Bake plate
6...E PDM sheet 7...Terminal FIG, 1 FIG, 2

Claims (3)

[Claims] (1) A sealing body for an electrolytic capacitor that is integrally formed with an unvulcanized or semi-vulcanized IIR rubber sheet and an uncured or semi-cured phenol (epoxy) bake plate, wherein the IIR rubber sheet contains an alkylphenol formaldehyde resin. The electrolytic method belongs to a resin vulcanization system using a vulcanizing agent, and is characterized in that an unvulcanized or semi-vulcanized EPDM sheet mixed with a vulcanizing agent is interposed between the IIR rubber sheet and the baking plate. Sealing body for capacitors. (2) Unvulcanized to semi-vulcanized IIR belonging to the resin vulcanization system using alkylphenol formaldehyde resin as the vulcanizing agent
A rubber sheet is layered with an unvulcanized or semi-vulcanized EPDM sheet mixed with a vulcanizing agent, and then an uncured or semi-cured phenol (epoxy) bake plate is layered and integrally formed under fusion conditions. A method for manufacturing a sealing body for electrolytic capacitors. (3) The method according to claim 2, wherein unvulcanized or semi-vulcanized EPDM sheets mixed with a vulcanizing agent are layered after being dissolved in an organic solvent.