JPH02194516A - Sealing member for electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To enhance a bonding property, 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 specific primer is used. 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 composed of isoprene, isobutylene and divinylbenzene; a vulcanized, unvulcanized or semivulcanized rubber sheet 4 is prepared; a bonding face, to a bakelite sheet, of this rubber sheetis coated with divinylbenzene 6 as a primer; an unhardened or semihardened phenolic (epoxy) bakelite sheet 5 is piled up on it; they are molded collectively under a molten bonding condition. During this process, when they are molded 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. This sealing member for electrolytic capacitor use 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 [Industrial Application Field] The present invention relates to an improvement in a sealing body for an electrolytic capacitor, and more specifically to a sealing body for an electrolytic capacitor having high organic solvent resistance and excellent airtightness. It relates to its manufacturing method.

C Conventional technology J Electrolytic capacitors are small, large capacity, inexpensive, and exhibit excellent characteristics such as smoothing rectified output, and are one of the important components of various electrical and electronic devices. An anode is an aluminum film that has been converted into a dielectric oxide film through electrolytic oxidation, and an element consisting of this and a current collector cathode is impregnated with an electrolytic solution (paste) and 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 electrolytic solution for electrolytic capacitors is generally made of ethylene glycol and boric acid, but this type of electrolytic solution is an aqueous electrolytic solution that produces condensed water, and the Recently, non-aqueous electrolytic solutions that do not contain substantially water have been increasingly used because of problems such as deterioration of the capacitor's appearance due to water deterioration and gasification of water 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 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. 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 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 it is impossible to improve their characteristics by improving the electrolyte, from the perspective of the overall performance of capacitor products, it is unavoidable 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 used1.
Special Publication No. 57-38182 describes a vulcanized rubber sheet and
Electrolysis characterized by using a sealing plate formed by bonding a filler-containing polypropylene plate containing filler such as talc with a polyolefin hot-melt film containing polypropylene or polyethylene as the main component, by thermocompression bonding. A capacitor is disclosed.

In addition, in column 2, line 34 to line 3n, line 4 of the same publication, it is stated that although butyl rubber (IIR) is the most stable material, it is used for electrolytic capacitors because there is a concern that it may release corrosive extractables. It is stated that practical use as a sealing material has not progressed much. In order to achieve this goal, this technology is investigating the use of ethylene propylene terpolymer (EPT) as the next best material to obtain a sealing plate that does not corrode.

However, in the case of EPT-lined baking, unlike butyl rubber-lined baking, it has a relatively high gas permeability, which causes a large amount of paste to come out, and the possibility of corrosion, etc. occurring cannot be ruled out because it is highly swellable with organic solvents. ,−
A sulfur-free, sulfur-free, or quinoid-based vulcanization system has poor adhesion to phenol, making it difficult to produce a product with high airtightness.

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 and fitability of the intervening rubber sheet.
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.

The present invention is made of a material that has a smaller amount of gas permeation than EPT and is difficult to swell, and has excellent fitability with the capacitor outer case.
By using a rubber sheet that has good adhesion to baking plates and applying a specific primer to the adhesion surface to improve adhesion, it is highly resistant to organic solvents, has excellent airtightness, and is suitable for a wide range of applications. The purpose is to obtain a sealing body for electrolytic capacitors.

[Means for Solving the Problems] According to the present invention, a rubber sheet made of a vulcanized copolymer consisting of isoprene, imbutylene, and divinylbenzene and mixed with additives, and an uncured or semi-cured phenol (epoxy) ) A sealing body for an electrolytic capacitor integrally formed with a baking plate, wherein the additive is selected from the group consisting of an organic peroxide, a carbon filler, and a metal oxide, and the adhesive surface of the rubber sheet to the beta plate is A sealing body for an electrolytic capacitor is provided, which is characterized in that divinylbenzene is applied as a primer.

Further, according to the present invention, a rubber sheet made of an uncured or semi-vulcanized copolymer polymer made of isoprene, imbutylene, and divinylbenzene and mixed with additives, and an uncured or semi-cured phenol (epoxy) bake plate. A sealing body for an electrolytic capacitor integrally formed with the additives selected from the group consisting of organic peroxides, carbon fillers, and metal oxides, and the additives are added as a primer to the adhesive surface of the rubber sheet to the beta plate. A sealing body for an electrolytic capacitor characterized by coating divinylbenzene is provided.

Isoprene, isobutylene, and divinylbenzene are commercially available as unvulcanized copolymer polymers, and a predetermined amount of additives as a vulcanizing agent are mixed therein to form vulcanized copolymer polymers or unvulcanized copolymers using conventional methods. A sulfurized to semi-vulcanized copolymer polymer is prepared. The amount of additive used as a vulcanizing agent is 1 to
The amount is 10 parts by weight.

The rubber sheet interposed between the Bakelite base material and the case opening may be unvulcanized, but a rubber sheet that has increased elasticity and improved adhesion through vulcanization will ensure a more secure fit. From this point of view, it is desirable that organic peroxides,
Vulcanization with additives from the group consisting of carbon fillers and metal oxides can improve adhesion to Bakelite substrates. however,
Generally, vulcanization causes a decrease in organic solvent resistance, so the degree of vulcanization of the copolymer using the above additives should be determined depending on the use and purpose of the electrolytic capacitor manufactured by comprehensively considering these factors. Should.

Furthermore, according to the present invention, for a copolymer consisting of isoprene, isobutylene, and divinylbenzene,
A vulcanized rubber sheet is mixed with an additive selected from the group consisting of organic peroxide, carbon filler, and metal oxide, and divinylbenzene is applied as a primer to the adhesive surface of the rubber sheet to the beta plate. , Layer an uncured or semi-cured phenol (epoxy) bake board on top of this, and! ! Provided is a method for manufacturing a sealing body for an electrolytic capacitor, which is characterized in that it is integrally molded under @ conditions.

At this time, it is sufficient to apply a small amount of divinylbenzene as a primer, but the amount of application should be small enough to form a substantially continuous thin layer of divinylbenzene on the adhesive surface.
For example, 1 to 2 g per adhesive surface ff1rrf with a sprayer.
Apply.

Pressure 30ksr/-~200kg/ad, temperature 130°
If integrally molded under fusion conditions of C to 200C, a suitable sealing body for an electrolytic capacitor can be obtained using a vulcanized rubber sheet.

Further, according to 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. A semi-vulcanized or semi-vulcanized rubber sheet is prepared, divinylbenzene is applied as a primer to the adhesive surface of the rubber sheet to the baking plate, an uncured or semi-cured phenol (epoxy) baking plate is placed over this, and the adhesive is applied under fusion conditions. Provided is a method for manufacturing a sealing body for an electrolytic capacitor, which is characterized in that the sealing body is integrally molded.

At this time, it is sufficient to apply a very small amount of divinylbenzene as a primer, but at least the amount of application should be such that a substantially continuous thin layer of divinylbenzene is formed on the adhesive surface.
For example, apply 91 to 2 g per adhesive area Lrrf using a sprayer.

Pressure 30kg/-~200kg/cffl, temperature 130
If integral molding is carried out under contact conditions of .degree. C. to 200.degree. C., a suitable sealing body for an electrolytic capacitor can be obtained using an unvulcanized or semi-vulcanized 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.

[Function j] The unique copolymer disclosed by the present invention has low gas permeability and less paste shedding, and has lower solvent affinity than EPT and swells and deteriorates, so it has excellent organic solvent resistance and residue retention ability. In itself, it is an extremely excellent material. Copolymers such as EPT do not have very good adhesion to the bake plate of the sealant, making it relatively difficult to create a sealant with high airtightness. Because it has a part that can react and crosslink and also has double bonds derived from other ingredients in its molecule, it promotes contact with the bake plate during integral molding, resulting in the formation of an extremely strong integrally molded sealing body. It is estimated that

The present invention provides other favorable effects on 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 fit of the sealing body to the coos while strengthening the properties without impairing them.

Furthermore, the present invention coats divinylbenzene as a primer between the copolymer and the baking plate to improve adhesion, thereby creating a material that is highly resistant to organic solvents, has excellent airtightness, and is suitable for a wide range of applications. The present invention provides a sealing body for an electrolytic capacitor.

[Effects of the Invention] According to the present invention, adhesiveness is further improved by using a copolymer consisting of isoprene, isobutylene, and divinylbenzene mixed with unique additives, and by using a specific primer. , has high organic solvent resistance,
Provided is a rubber-coated baked sealing body for an electrolytic capacitor with low gas permeability and little paste escape.1 The sealing body for an electrolytic capacitor according to the present invention has high resistance to organic solvents, and therefore contains γ- as a component of the electrolytic solution. Organic solvents such as butyrolactone (BL) and dimethylformamide (DMF) can be used, and since there is less paste shedding than with EPT adhesive, 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.

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

Vulcanized isobutylene isopropylene divinylbenzene copolymer SRF carbon hard clay Stearic acid nO Dicumyl peroxide Uncured or semi-vulcanized isobutylene isopropylene divinylbenzene copolymer SRF carbon 50 Hard clay 100 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 produce a rubber sheet with a thickness of 1.5 mm.

Preparation of sealing body A sprayer was used to inject ln between the copolymer rubber sheet of Examples 1 and 2 prepared as described above and an uncured or semi-cured phenol (epoxy) bake plate.
After applying divinylbenzene in an amount of 1.2z per f, the sheets were bonded together under the next fused strip and integrally molded to produce a sealing body for an electrolytic capacitor.

Temperature: 165°C Time: 10 minutes Pressure: 150 to 2/aA Condensate J Electrolytic capacitor equipped with the sealing body according to Example 1, electrolytic capacitor equipped with the sealing body according to Example 2, and EPT having the same thickness as the sealing body. Instead of manufacturing a conventional electrolytic capacitor (Comparative Example 1), a size 20
φX40. l! , an electrolytic capacitor with a rating of 63 WV and 820 μF was manufactured.

Fig. 1 shows a cross-sectional view of an electrolytic capacitor, and Fig. 2 shows a cross-sectional view of a cap 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 baking plate, 6 is a coated divinylbenzene, and 7 is a terminal.

1 blood x 1 Electrolytic capacitors equipped with the sealing body according to Example 1, electrolytic capacitors equipped with the sealing body according to Example 2, and conventional tU capacitors (Comparative Example 1) using EPT of the same thickness as the sealing body were subjected to high temperature Paste comes off due to long-term use! ! ? Changes in capacitance 1 (Cap) and changes in dielectric loss tangent (tan δ) were measured.

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

Example 1 -2.7M Example 2 2.6rstr Comparative Example 1 -24.3■ Test results for quantity and positive The test results for the electrolytic capacitor equipped with the sealing body according to Example 1, which were measured over time, 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, the test results for the 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, when an organic solvent such as γ-butyrolactone is not used as a component of the electrolyte, has less paste omission than EPT pasted baking, improved performance, and whitening of the length. 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... Element 2... Case 3... Sealing body 4... Copolymer sheet 1-5... Baking plate 6... Coated divinylbenzene 7... Terminal FIG, 1 FIG, 3 FIG, 4 FIG, 2 at(1±l1Ii111h+l. 11σC

Claims (4)

[Claims] (1) A sealing body for electrolytic capacitors that is integrally formed with a rubber sheet, which is a vulcanized copolymer made of isoprene, isobutylene, and divinylbenzene and mixed with additives, and an uncured or semi-cured phenol (epoxy) bake plate. The electrolytic method is characterized in that the additive is selected from the group consisting of organic peroxides, carbon fillers, and metal oxides, and divinylbenzene is applied as a primer to the adhesive surface of the rubber sheet to the baking plate. Sealing body for 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 organic peroxide, carbon filler, and metal oxide, and divinylbenzene is applied as a primer to the adhesive surface of the rubber sheet to the baking plate. A sealing body for electrolytic capacitors featuring: (3) A vulcanized rubber sheet is prepared by mixing an additive selected from the group consisting of organic peroxide, carbon filler, and metal oxide with a copolymer consisting of isoprene, isobutylene, and divinylbenzene. The adhesive surface of this rubber sheet to the baking plate is coated with divinylbenzene as a primer, and an uncured or semi-cured phenol (epoxy) baking plate is layered on top of this, and the product is integrally formed under fusion conditions. A method for manufacturing a sealing body for electrolytic capacitors. (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. Prepare a rubber sheet, apply divinylbenzene as a primer to the adhesive surface of this rubber sheet to the baking plate, layer this with an uncured or semi-cured phenol (epoxy) baking plate, and integrally mold it under fusion conditions. A method of manufacturing a sealing body for an electrolytic capacitor, characterized in that: