JP2000086839A - Method for crosslinking etylene/propylene rubber mixture having isoprene/isobutylene rubber or isoprene/ isobutylene rubber and ethylidene norbornene as third component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for crosslinking an ethylene/propylene rubber mixture having an isoprene/isobutylene rubber or an isoprene/isobutylene rubber and ethylidene norbornene as the third component. SOLUTION: An ethylene/propylene rubber mixture having, as the third component, an isoprene/isobutylene rubber or an isoprene/isobutylene rubber and ethylidene norbornene is added with an alkylphenol/formaldehyde resin and one or more components selected from a metal deactivator, an epoxy resin, a basic carbonate salt and a hydrotalcite and then, crosslinked. This method can produce a crosslinked rubber with a reduced amount of elution of chlorine and is a very good method for preparing an electrolytic capacitor sealing rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing a synthetic rubber, isoprene / isobutylene rubber or a mixture of isoprene / isobutylene rubber and ethylene / propylene rubber having ethylidene norbornene as a third component, by using an alkylphenol / formaldehyde resin and an epoxy resin. The present invention relates to a method of crosslinking using a resin, a metal deactivator, and one or more compounds selected from basic carbonates and hydrotalcites, and a sealing rubber product particularly obtained by crosslinking by the method, particularly for electrolytic capacitors. .

[0002]

2. Description of the Related Art Isoprene / isobutylene rubber (hereinafter sometimes abbreviated as butyl rubber) is produced by copolymerization of isoprene and isobutylene and has an unsaturation of 0.5 m.
ol% to 3 mol%, which is a known synthetic rubber. Crosslinked elastomer (crosslinked rubber of butyl rubber) has features such as low gas permeability, weather resistance, electrical insulation, heat resistance, vibration resistance, chemical resistance to acids and alkalis, and low water absorption. It is used for rubber, hoses, automobile tubes, rubber stoppers, curing bags, and the like.

[0003] Ethylene propylene diene rubber (hereinafter abbreviated as EPDM) is a terpolymer of ethylene, propylene and diene, and the diene employed as the third component is 1,4-hexadiene or ethylidene. Norbornene and the like. The ethylene-propylene rubber having ethylidene norbornene as the third component used in the present invention is EPDM containing ethylidene norbornene as the third component (diene component). EPDM is a known synthetic rubber having excellent heat resistance, weather resistance and electrical insulation. As a method for crosslinking butyl rubber, three methods are known: sulfur crosslinking, quinoid crosslinking, and resin crosslinking. [The Vanderbilt Rub
ber Hand Book (RTVanderbilt Company, Inc., 1990), 13th edition, pp. 92-105].

[0004] Sulfur crosslinking is carried out by using sulfur in combination with a crosslinking accelerator such as thiuram or thiazole, and is widely adopted as a crosslinking method for producing vibration-proof rubber, automobile tubes, rubber hoses and the like.

[0005] The quinoid cross-linking is carried out by using a combination of lead red, lead dioxide and quinone dioxime or benzoyl quinone dioxime, and is adopted as a cross-linking method for producing electric wire coating, tank lining and the like. Since the crosslinking speed is high, it is suitable for high-speed continuous crosslinking such as covering of electric wires.

Resin crosslinking is carried out by using an alkylphenol-formaldehyde resin in combination with an inorganic halogen compound such as tin chloride or ferric chloride, a halogen-containing elastomer such as chloroprene rubber or chlorosulfonated polyethylene, or a halogenated alkylphenol-formaldehyde. It is performed by a resin and is employed in a crosslinking method for producing a curing bag used for producing a tire.

[0007] The above three methods have been adopted as a crosslinking method for producing a sealing rubber for an electrolytic capacitor (hereinafter referred to as a sealing rubber).

In order to enhance the performance of electrolytic capacitors, sealing rubber is required to have heat resistance, characteristics that reduce the possibility of metal corrosion with little elution chlorine, and excellent compression set, etc. Crosslinking with alkylphenol / formaldehyde resin is a crosslinking method. The method has been adopted as a method satisfying the required characteristics.

A method of not using a halogen compound in combination with a phenol-formaldehyde resin crosslinking method has been known for a long time. "POLYSAR Butyl Handbook" (Polymer Corp.
Oration Limited Sarnia, Canada, published in 1966), page 117, introduces the following techniques for methods that do not use halogen compounds in combination.

"Polytherbutyl rubber compounds having excellent heat resistance and low compression set can be obtained by crosslinking with a dimethylphenol resin. Generally, an activator containing halogen is used in combination with the resin. It is possible to crosslink at a high temperature to achieve sufficient cross-linking, particularly with a polystyrene butyl rubber having a high degree of unsaturation. "Thus, butyl rubber has a temperature of 180 ° C. to 210 ° C. Good crosslinking rubber can be obtained at the crosslinking temperature. As long as the crosslinking is carried out at a high temperature, there is no need to add an activator containing a halogen (crosslinking aid) to the crosslinking agent system. The obtained crosslinked rubber has excellent properties such as heat resistance and low compression set.

[0011] However, recently, there has been a demand for a product in which the elution of chlorine from a crosslinked rubber product has been reduced as much as possible and for a rubber product having a high rubber hardness from the viewpoint of improving the performance of a capacitor. At present, mere high-temperature crosslinking such as the above-mentioned resin crosslinking under high temperature cannot satisfy the performance. And the first problem that can not meet such performance is:
Although a raw material to which a halogen compound has not been added is blended and used, chlorine, which is a kind of halogen, is eluted, and the amount of elution is not constant. The elution of chlorine from the sealing rubber for the electrolytic capacitor causes corrosion of the lead wire of the capacitor, and also causes the corrosion of the aluminum electrode. Therefore, it is necessary to suppress the elution of chlorine from the sealing rubber.

There is no known literature on the relationship between the crosslinking of phenol / formaldehyde resin of butyl rubber due to high temperature and the elution of trace amounts of chlorine.

[0013] Therefore, a sealing rubber is produced by using a butyl rubber raw material having a low chlorine content as an impurity, carbon black, clay, talc and the like, but this measure is not theoretically appropriate.

The butyl rubber raw material contains chlorine compounds such as aluminum chloride and carbon tetrachloride mixed in during the production thereof.
Contains at least 00 ppm. These are included in the production process of butyl rubber and cannot be removed.
Clay and talc are natural products, chlorine is 100
It is impossible to select and use clay and talc which contain at least ppm and do not contain chlorine. Nor can it be removed. Carbon black also contains about 30 ppm of chlorine, and at present, it is impossible to remove such chlorine from the raw material itself from the standpoint of a rubber product manufacturer. Also, the amount of eluted chlorine is not constant if it is proportional to the total amount of chlorine in the raw rubber compound for producing the sealing rubber. No known literature discusses these issues, but those of ordinary skill in the art are aware of the facts, for unknown reasons.

[0015] The second problem is that such a performance cannot be satisfied. The second problem is that a crosslinked butyl rubber having a degree of 85 ° C or more measured by a JIS-A hardness tester is used to produce a sealing rubber by crosslinking a phenol / formaldehyde resin at a high temperature. There is a limit. The reason is that the required properties of the sealing rubber include electrical insulation, and carbon black, which is used as a rubber reinforcing agent and a filler to increase hardness, has a limited amount of addition to reduce insulation. is there. The upper limit of the addition amount is 60 parts by weight based on 100 parts by weight of butyl rubber, and there is no known method for producing a crosslinked butyl rubber having a high hardness without changing the addition amount of carbon black. The above two problems are unsolved problems.

As a method for crosslinking ethylene / propylene rubber containing ethylidene norbornene as a third component, four methods are known: sulfur crosslinking, organic peroxide crosslinking, quinoid crosslinking, and resin crosslinking. [Rubber Industry Handbook (4th edition), page 302 (published by the Japan Rubber Association)].

Sulfur crosslinking is carried out by using sulfur in combination with a crosslinking accelerator such as thiuram or thiazole, and is widely used as a crosslinking method for producing heat-resistant hoses, gaskets for automobiles and buildings, roofing sheets, and the like.

The organic peroxide crosslinking provides a low compression set, and is used as a method for producing industrial rubber products such as packing.
Widely adopted.

The cross-linking method using sulfur and the cross-linking method using an organic peroxide are generally used as cross-linking methods for EPDM.

Although quinoid cross-linking and resin cross-linking are introduced in technical books on rubber technology, they are hardly adopted as a cross-linking method for industrially producing rubber products.

The quinoid cross-linking is carried out by using a combination of leadtan, lead dioxide and quinonedioxime or benzoylquinonedioxime. However, it is said that burning (scorch) occurs due to a high crosslinking speed, so that practical use is difficult.

The resin crosslinking is carried out in combination with an alkylphenol / formaldehyde resin and a crosslinking aid such as an inorganic halogen compound such as tin chloride or ferric chloride, a halogen-containing elastomer such as chloroprene rubber or chlorosulfonated polyethylene, or This is done with a halogenated alkylphenol-formaldehyde resin.

When a sealing rubber is produced from EPDM as a raw material, a crosslinking method using an organic peroxide is employed.
No other crosslinking methods have been employed. The reason is EPD
The method of crosslinking with an organic peroxide of M not only allows crosslinking in a short time, but also satisfies properties required for a sealing rubber, such as heat resistance, low compression set, and insulation. However, high gas permeability is a disadvantage, but butyl rubber may be used or EPDM
Is used.

In the case of butyl rubber, when heated to 100 ° C. or higher, the hardness of the rubber is reduced.
In the case of M, the crosslinked rubber has a property of being cured (increased in hardness) when heated to 100 ° C. or more, and is called a so-called thermosetting rubber. Known methods for reducing the thermal softening properties of butyl rubber include EPDM.
Is performed.

When a sealing rubber is produced by cross-linking butyl rubber with an alkylphenol-formaldehyde resin,
A method of adding and mixing EPDM can be considered from known techniques.However, as for cross-linking of EPDM with an alkylphenol-formaldehyde resin, research on a cross-linking system not using a halogen compound is insufficient, and butyl rubber and EPDM are cross-linked by alkylphenol-formaldehyde resin cross-linking.
There is no known technique for producing a sealing rubber product from a mixture obtained by mixing the above.

Regarding the above-mentioned unsolved problem using butyl rubber as a raw material, the problem to be solved is common if the synthetic rubber obtained by mixing butyl rubber and EPDM is used as a raw material and crosslinked with an alkylphenol-formaldehyde resin. . However, there is no known literature on the sealing rubber which describes such a problem.

[0027]

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a method of crosslinking a butyl rubber with an alkylphenol-formaldehyde resin for producing a crosslinked rubber product having a small amount of dissolved chlorine and a high hardness. To provide. Another object of the present invention is to provide a sealing rubber product for an electrolytic capacitor by the crosslinking method. Next, a second object of the present invention is to provide a method of crosslinking a mixture of EPDM containing butyl rubber and ethylidene norbornene as a third component using an alkylphenol-formaldehyde resin. It is to provide a cross-linking method for producing rubber products. Another object of the present invention is to provide a sealing rubber product for an electrolytic capacitor by the crosslinking method. Still other objects of the present invention will become more apparent from the following description.

[0028]

SUMMARY OF THE INVENTION The above-mentioned object of the present invention is as follows.
For isoprene / isobutylene rubber or a mixture of isoprene / isobutylene rubber and ethylene / propylene rubber having ethylidene norbornene as the third component, alkylphenol / formaldehyde resin, metal deactivator, epoxy resin, basic carbonate and hydrocarbon A method of crosslinking by adding one or more compounds selected from talcite or, additionally, carbon black and clay and, if necessary, one or more of zinc oxide, stearic acid and an antioxidant; and an electrolytic capacitor obtained by the method. Achieved by sealing rubber. More specifically, (1) 100 parts by weight of isoprene / isobutylene rubber or a mixture of 68 to 92 parts by weight of isoprene / isobutylene rubber and 32 to 8 parts by weight of ethylene / propylene rubber having ethylidene norbornene as a third component
16 parts by weight to 20 parts by weight of an alkylphenol / formaldehyde resin and 0.5 parts by weight of a metal deactivator,
5 parts by weight to 5 parts by weight, 0.5 parts by weight to 5 parts by weight of an epoxy resin, and 0.5 parts by weight to 5 parts by weight of one or more compounds selected from a basic carbonate and hydrotalcite. A method for crosslinking, and a sealing rubber for an electrolytic capacitor obtained by crosslinking by the crosslinking method.

(2) Isoprene / isobutylene rubber 10
0 parts by weight or 100 parts by weight of a mixture of 68 parts by weight to 92 parts by weight of isoprene / isobutylene rubber and 32 parts by weight to 8 parts by weight of ethylene propylene rubber having ethylidene norbornene as a third component, and 16 parts by weight of an alkylphenol / formaldehyde resin To 20 parts by weight, 0.5 to 5 parts by weight of a metal deactivator, 0.5 to 5 parts by weight of an epoxy resin, and one or more kinds selected from basic carbonates and hydrotalcites. 0.5 to 5 parts by weight of a compound and 30 parts by weight of carbon black as a filler
A method for crosslinking by adding 60 parts by weight and 50 to 170 parts by weight of clay, and a sealing rubber for an electrolytic capacitor obtained by crosslinking by the crosslinking method.

(3) In the crosslinking method of the above (1) and (2), 100 parts by weight of isoprene / isobutylene rubber or 68 parts by weight to 92 parts by weight of isoprene / isobutylene rubber is further added.
A mixture 1 of 32 parts by weight of ethylene-propylene rubber and 8 parts by weight of ethylene propylene rubber having ethylidene norbornene as a third component.
A method of adding one or more of zinc oxide, stearic acid, and an antioxidant to 5 parts by weight, and crosslinking the same by 00 parts by weight, and an electrolytic capacitor obtained by crosslinking by the crosslinking method. Achieved by a rubber seal.

The feature of the present invention is that a metal deactivator, a specific epoxy resin,
It is to crosslink by adding one or more compounds selected from basic carbonates and hydrotalcite. Therefore, it can be said that this is an extremely excellent method for producing a sealing rubber for a capacitor, for example.

In high-temperature crosslinking of butyl rubber with an alkylphenol-formaldehyde resin, it is unknown why chloride is not widely added to the rubber but chlorine is eluted. There is a phenomenon that stains similar to stains of the mold occur on the mold. There are no known reports discussing this problem. The present inventor has considered as follows, and as a result, has come to develop a product in which the amount of chlorine eluted from the sealing rubber is extremely reduced by using three kinds of compounds in combination. That is, the present inventors have a known fact that the alkylphenol-formaldehyde resin is activated by a halogen compound in the crosslinking of butyl rubber. Then, it was considered that the unstable chlorine compound contained as an impurity in the raw material was activated (destabilized) by the alkylphenol / formaldehyde resin and eluted.

The chlorine compound as a source of chlorine which can be dissolved is supplied from butyl rubber as a raw material, clay or talc added as a filler, carbon black and a small amount of added chemicals such as a crosslinking agent and an antioxidant. You. Although the structure of each of the chlorine compounds is unknown, a person skilled in the art naturally prepares a compounding formula for a sealing rubber within a known range.
Contains 0 ppm or more of chlorine. Some of the chlorine compounds, whose composition is unknown, are considered to be changed to easily eluted chlorine by being activated (stabilized) by alkylphenol / formaldehyde resin. This led to the development of a new sealing rubber.

The isoprene / isobutylene rubber (butyl rubber) used in the present invention is produced by copolymerization of isoprene and isobutylene, and generally has an unsaturation of 0.5M.
ol% to 3.0 Mol%, which is a known synthetic rubber. The scope of the present invention does not include halogenated butyl rubber obtained by adding bromine or chlorine to isoprene / isobutylene rubber. The ethylene-propylene rubber containing ethylidene norbornene as a third component used in the present invention (sometimes abbreviated as ethylene-propylene rubber) is a terpolymer of ethylene, propylene and a diene,
Among them, EPDM contains ethylidene norbornene (ENB) as a diene component (third component). The ethylene-propylene rubber of the present invention is produced by copolymerizing ethylene, propylene and ethylidene norbornene using a vanadium catalyst, an organoaluminum-based co-catalyst, a metallocene catalyst and the like, and the amount of the third component is an iodine value, generally 5%. ~ 30,
The content of propylene is a known synthetic rubber having a content of 8 mol% to 50 mol%.

The alkylphenol used in the present invention
The formaldehyde resin is not particularly limited as long as it is an alkylphenol-formaldehyde resin that can be effectively used for the resin crosslinking of the butyl rubber of the present invention, and is not particularly limited. A compound having a methylol group having a relatively low molecular weight can be suitably used. .

For example, as shown by the following formula, n is 0 to
A mixture of low molecular weight compounds of 10 (wherein R represents a C ₁ -C ₁₀ aliphatic alkyl group and R ′ represents —CH ₂ — or —CH ₂ OCH ₂ —) can be suitably used. .
Such compounds are available, for example, under the trade name TACKIR
OL) 201 (product of Taoka Chemical Industry Co., Ltd.), HITANOL 2501 (product of Hitachi Chemical Co., Ltd.),
SP-1044, SP-1045 [Schenectady Intern
ational, Inc. (U.S.A.) products].

[0037]

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The use of a halogenated alkylphenol-formaldehyde resin having a methylol group substituted with bromine or a halogenated alkylphenol-formaldehyde resin having a benzene nucleus substituted with halogen is not suitable for the purpose of the present invention. Not included in range.

The amount of the alkylphenol / formaldehyde resin to be added depends on the amount of the isoprene / isobutylene rubber 1
00 parts by weight or 16 parts by weight to 20 parts by weight with respect to 100 parts by weight of a mixture of 68 parts by weight to 92 parts by weight of isoprene / isobutylene rubber and 32 parts by weight to 8 parts by weight of ethylene / propylene rubber having ethylidene norbornene as a third component Department. When producing a sealing rubber having a high hardness, if it is less than 16 parts by weight, insufficient hardness is caused. Even if it is used in an amount of more than 20 parts by weight, no particularly excellent effect can be obtained.

Next, the metal deactivator used in the present invention is not particularly limited as long as it can be effectively used in the present invention. Specifically, for example, 3- (N-salicyloyl)
Amino-1,2,4-triazole, 1,2,3-benzotriazole, 1,2,3-benzotriazole sodium salt, tolyltriazole, tolyltriazoleamine salt, tolyltriazole potassium salt, decamethylenedicarboxylic acid disalicylo 100 parts by weight of a mixture of 100 parts by weight of isoprene / isobutylene rubber or 68 parts by weight to 92 parts by weight of isoprene / isobutylene rubber and 32 parts by weight to 8 parts by weight of ethylene / propylene rubber having ethylidene norbornene as a third component. One or more types are added in an amount of 0.5 to 5 parts by weight.

The purpose of this addition is to stabilize the heavy metal contained in the rubber in a minute amount in the sealing rubber, and to remove the influence of the heavy metal on the aluminum of the lead wire of the electrolytic capacitor, the aluminum foil and the container contained therein. is there. These chemicals generally produce a chelate compound with a heavy metal, stabilize the heavy metal, and are used as a copper damage inhibitor for polyolefin resins or a metal rust inhibitor.

When the amount is less than 0.5 part by weight, the effect is small, and the addition of more than 5 parts by weight is not necessary for the intended effect, and the addition of 5 parts by weight or less is sufficient. The eluted chlorine is reduced by the addition of a metal deactivator.

The effect of the metal deactivator on the crosslinking of the butyl rubber with the alkylphenol-formaldehyde resin is not constant, and may act to delay the crosslinking. An example of this is tolyltriazole, and on the contrary, a very good one that simultaneously acts as a crosslink accelerator for alkylphenol-formaldehyde resins is decamethylenedicarboxylic acid disalicyloyl hydrazide, which has little effect on the crosslinking rate. , 3- (N-salicyloyl)
Amino-1,2,4-triazole. Therefore, it is preferable to use them in an appropriate combination.

The epoxy resin used in the present invention may be any epoxy resin which can be effectively used in the present invention. Examples thereof include a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, a triphenylmethane type epoxy resin, and a naphthol. Epoxy resins selected from the group consisting of modified novolak type epoxy resins are particularly preferred. The amount of epoxy resin used is 100 parts by weight of 100 parts by weight of isoprene / isobutylene rubber or 100 parts by weight of 68 parts by weight to 92 parts by weight of isoprene / isobutylene rubber and 32 parts by weight to 8 parts by weight of ethylene / propylene rubber having ethylidene norbornene as a third component. One or more types are added in an amount of 0.5 to 5 parts by weight.

In the present invention, the use of an epoxy resin in which a halogen such as bromine is substituted on the benzene nucleus and the alkyl group is not preferable for the purpose of the present invention and is not included in the scope of the present invention.

Hereinafter, the epoxy resin used in the present invention will be described in more detail.

The phenol novolak type epoxy resin is a reaction product of a phenol novolak resin and epichlorohydrin, and is represented by the following structural formula.

An epoxy equivalent is 300 g / eq or less, and a resin having a softening point (° C.) of 100 ° C. or less by a ring and ball method is preferable.

[0049]

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The cresol novolak type epoxy resin is a reaction product of O-cresol novolak resin and epichlorohydrin, and is represented by the following structural formula. Epoxy equivalent is 300 g / eq or less, and resin having a softening point (° C.) of 100 ° C. or less by a ring and ball method is preferable.

[0051]

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The naphthol-modified novolak type epoxy resin is represented by the following formula, and has an epoxy equivalent of 225 g / eq.
245 g / eq, trade names NC-7000 and 702
This is a naphthol-modified novolak epoxy resin sold as No. 0 series (manufactured by Nippon Kayaku Co., Ltd.). Softening point (° C.) is a resin having a softening point of 100 ° C. or less according to a ring and ball method.

[0053]

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The triphenylmethane type epoxy resin is
For example, an epoxy resin represented by the following structural formula and marketed under the trade names of EPPEN500 series and FAE series (manufactured by Nippon Kayaku Co., Ltd.). Epoxy equivalent 30
It is 0 g / eq or less, and the softening point (° C.) is 100 ° C. or less according to the ring and ball method.

[0055]

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The purpose of the epoxy resin used in the present invention is isoprene / isobutylene rubber or isoprene / isobutylene rubber.
The effect of accelerating the crosslinking of alkylphenol / formaldehyde resin to a mixture of ethylene / propylene rubber with isobutylene rubber and ethylidene norbornene as the third component, and by adding a small amount, it is possible to increase the hardness of the crosslinked rubber without increasing the amount of carbon black. In order to further capture free chlorine, it has a combined effect.

The four particularly preferred epoxy resins specified in the present invention are supplied in a solid state, and the desired effects can be effectively obtained by adding and kneading them with a closed kneading machine. The chlorine which is reactive with the epoxy resin contained in the rubber compound (mixture obtained by kneading the rubber raw materials) enhances the trapping efficiency of chlorine due to heat generation of the rubber compound in the kneading step. Further, the compound to which the epoxy resin is added exhibits extremely good storage stability with stable Mooney viscosity.

The amount of the epoxy resin used is 100 parts by weight of isoprene / isobutylene rubber or 68 to 92 parts by weight of isoprene / isobutylene rubber, and ethylene / propylene rubber 32 containing ethylidene norbornene as a third component.
For 100 parts by weight of the mixture of 8 parts by weight to 8 parts by weight, 0.1 parts by weight.
5 to 5 parts by weight are added. If the amount is less than 0.5 part by weight, the effect is small, and if the amount is more than 5 parts by weight, the required properties are not required for increasing the hardness, promoting cross-linking, and trapping chlorine for the purpose of producing a sealing rubber. This is achieved by the following additions.

The raw material of the epoxy resin contains hydrolyzable chlorine. Epoxy resin used in the present invention,
Epoxy resins for LSI encapsulation with a small amount of hydrolyzable chlorine are preferred.

Next, the basic carbonate used in the present invention is:
Although not particularly limited, specific examples include basic magnesium carbonate and basic aluminum carbonate. As the hydrotalcite, either natural hydrotalcite or synthetic hydrotalcite can be used. These are inorganic compounds known as a supplement for hydrogen chloride of vinyl chloride resin.

Natural hydrotalcite and synthetic hydrotalcite (trade name DHT manufactured by Kyowa Chemical Industry Co., Ltd.)
-4A) is shown below.

Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O (natural product) MgAl ₂ (OH) ₆ CO ₃ .mH ₂ O (synthetic product) The amount of basic carbonate and hydrotalcite used is as follows: To 100 parts by weight of 100 parts by weight of isoprene / isobutylene rubber or 100 parts by weight of a mixture of 68 to 92 parts by weight of isoprene / isobutylene rubber and 32 to 8 parts by weight of ethylene / propylene rubber having ethylidene norbornene as a third component. 5 to 5 parts by weight are added. If the amount is less than 0.5 part by weight, the effect is small, and if the amount is more than 5 parts by weight, the crosslinking rate is reduced or the properties of compression set are deteriorated. In addition, 2 of compounds selected from basic carbonate and hydrotalcite
When two or more kinds are used in combination, the total of the compounds is 0.5 to 5
Used to be parts by weight.

The alkylphenol / formaldehyde resin is activated by an unstable halogen compound, and has a property of promoting the crosslinking. The compounding formula for stabilizing the unstable halogen compound according to the present invention has a low crosslinking rate. However, by cross-linking with a combination of one or more compounds selected from the above metal deactivators, epoxy resins and basic carbonates and hydrotalcite, the rubber is independent of carbon black. This makes it possible to increase the hardness, to reduce the amount of eluted chlorine, and to reduce the cross-linking rate of the raw material rubber, and to provide an excellent sealing rubber.

The carbon black used in the present invention is
Any known carbon black such as channel black, furnace black, thermal black and acetylene black can be used. It is an indispensable filler to obtain good crosslinked rubber strength.

The amount of carbon black used is 100 parts by weight of isoprene / isobutylene rubber or 68 to 92 parts by weight of isoprene / isobutylene rubber and 32 to 8 parts by weight of ethylene / propylene rubber having ethylidene norbornene as a third component. For 100 parts by weight of the mixture,
30 parts by weight to 60 parts by weight are added. The lower limit may be an amount within a range in which the reduction in cross-linking properties is permissible. However, the upper limit of 60 parts by weight or more causes a decrease in electrical insulation, making it impossible to produce a good sealing rubber.

The clay used in the present invention is called kaolin clay, kaolinite or the like, and includes aluminum oxide,
It contains silicon oxide as a main component and has a unique chemical composition and chemical properties depending on the place of production. The main production areas are Georgia and South Carolina, USA, and are known fillers. The clay includes surface-treated clay such as vinyl silane and amino silane, and fired clay fired at a high temperature. In the present invention, any clay can be used.

A particularly preferred clay in the present invention is calcined clay, and good electrical insulation can be obtained by using calcined clay.

The amount of clay used is 100 parts by weight of isoprene / isobutylene rubber or a mixture of 68 parts to 92 parts by weight of isoprene / isobutylene rubber and 32 parts to 8 parts by weight of ethylene / propylene rubber having ethylidene norbornene as a third component. 50 to 170 parts by weight are added to 100 parts by weight.

The lower limit of the amount used is determined in consideration of the maximum amount of carbon black (60 parts by weight). That is, when 60 parts by weight of carbon black is added to 100 parts by weight of rubber, the total amount of clay added is 110 parts by weight. Is required to be 50% or less.

The upper limit is 230 parts by weight, including the maximum amount of carbon black to be added of 60 parts by weight. The content of butyl rubber in the compound is determined from the ratio at which good physical properties can be obtained as a crosslinked rubber. ing. The addition of an excess filler decreases the physical properties of the crosslinked rubber.

50% to 170% by weight of the clay added to 100 parts by weight of the rubber component is 50% or less, that is, 2% or less.
From 5 to 85 parts by weight, one or more kinds selected from the group consisting of talc, heavy calcium carbonate, light calcium carbonate, mica, natural silica, and synthetic silica are added at an arbitrary ratio by replacing clay. You may.

Talc is a known filler mainly called hydrated magnesium silicate and imported from China.

Heavy calcium carbonate is obtained by pulverizing crystalline limestone or marble, and light calcium carbonate is obtained by using limestone as a raw material, such as a carbon dioxide compounding method, a lime milk soda compounding method, a calcium chloride soda compounding method, or the like. Is a known filler manufactured by the company.

Mica is a general term for a group of silicate minerals, and includes kaolinite and talc, but includes sericite (sericite), muscovite (muscovite), phlogopite (phlogopite) and the like. It is a known filler which is called.

Natural silica and synthetic silica are silicon oxides, which are known fillers usually called white carbon.

These fillers are used by those skilled in the art of rubber.
%, The clay may be replaced and used in combination.

The zinc oxide and stearic acid used in the present invention are added as a crosslinking aid and a crosslinking promoting aid. Zinc oxide refers to a vulcanizing (crosslinking) agent, a vulcanization accelerator, and zinc oxide, which are referred to as three elements of crosslinking, and are added from the viewpoint of being one component of the element. The amount used is 100 parts by weight of isoprene / isobutylene rubber or 68 parts by weight to 92 parts by weight of isoprene / isobutylene rubber, and ethylene / isobutylene rubber containing ethylidene norbornene as a third component.
With respect to 100 parts by weight of a mixture of 32 parts by weight to 8 parts by weight of propylene rubber, 3 parts by weight to 5 parts by weight of zinc oxide and 1 part by weight to 3 parts by weight of stearic acid.

The antioxidant does not always need to be added to the sealing rubber. However, there is no assurance that the addition of the anti-aging agent has no effect on the product. It is added from the viewpoint of ensuring safety recognized by those skilled in the rubber industry. The difference in crosslinked rubber properties with and without the addition of an antioxidant could not be confirmed,
When added, it is desirable to add an antioxidant which does not contain a sulfur atom or a halogen atom to the structure of the antioxidant.

As an anti-aging agent used as an anti-aging agent for butyl rubber, one of historically old chemicals,
Among the hindered phenol-based antioxidants, those containing no sulfur atom in the structure are preferable. For example, Irganox 1010 manufactured by Nippon Ciba Geigy Co., Ltd.
Commercially available pentaerythritol-tetrakis [3
-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] is mentioned as an example. The effect of the crosslinking method of the present invention on the crosslinking rate was confirmed, but the effect was extremely small with only a slight delay in crosslinking, and this is an example of a desirable antioxidant.

In carrying out the present invention, the crosslinking conditions are not particularly limited, but the crosslinking temperature is generally 170 ° C. to 210 ° C.
In the heat transfer press used by those skilled in the art, primary crosslinking is performed for 5 minutes to
Perform 10 minutes, secondary cross-linking in an electric oven at 170 ° C. to 2
It is preferable to carry out at 10 ° C. for 30 minutes to 4 hours.

[0081]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in more detail with reference to Examples and Comparative Examples. In addition, all the numerical values of the raw material mixing amount in the table of the examples represent parts by weight.

The physical properties were measured according to JIS-K6301. The crosslinking curve was determined using an oscillating rheometer (ASTM100 type) manufactured by Toyo Seiki Co., Ltd.

[0083]

EXAMPLES Examples 1 and 2, Comparative Example 1 100 parts by weight of isoprene / isobutylene rubber were mixed with 3- (N-salicyloyl) amino-1,
1 part by weight of 2,4-triazole, 1.5 parts by weight of cresol novolak type epoxy resin for LSI encapsulation as an epoxy resin, 2 parts by weight of synthetic hydrotalcite as a basic carbonate, and alkylphenol as a crosslinking agent Example 1: Formulation for electrolytic capacitor to which 18 parts by weight of formaldehyde resin was added, and triphenylmethane type epoxy for LSI sealing instead of 1.5 parts by weight of cresol novolak type epoxy resin for LSI sealing. Table 1 shows the composition in which 2 parts by weight of the resin was added, and Table 2 shows the test results.

For comparison, the composition of Example 1 from which the metal deactivator, epoxy resin and basic carbonate were removed is shown as Comparative Example 1. FIG. 1 shows crosslinking curves measured at 190 ° C. by the oscillating rheometers of Example 1 and Comparative Example 1.

The amount of eluted chlorine was measured by performing primary crosslinking at 190 ° C. for 10 minutes and then using a convection electric oven at 200 ° C.
The crosslinked rubber obtained by performing the secondary crosslink for 2 hours was powdered with a grinder to obtain a sample. 1,000c pure water
To c was added 100 g of boric acid and 3 g of ammonium borate, which are condenser grades, to prepare an extract. A powdery rubber sample (2 g) was weighed in 100 cc of the extract and placed in a stainless steel net with a handle to prevent the rubber powder from floating. The extract was boiled for 30 minutes while constantly moving the net to stir so that sufficient extraction could be performed. The extract, which was reduced in volume by evaporation, was supplied with pure water and adjusted to 100 cc to obtain a test solution. The value determined by potentiometric titration (silver nitrate titration) was shown as the amount of eluted chlorine.

As is clear from Table 2, the amount of eluted chlorine was
Comparative example in which 3- (N-salicyloyl) amino-1,2,4-triazole, cresol novolak-type epoxy resin or triphenylmethane-type epoxy resin, and synthetic hydrotalcite are added and cross-linked, so that no addition is made. 1 and the amount of eluted chlorine is 1/6 to 1/9,
It can be seen that it is greatly reduced. This shows that a crosslinked rubber having a high JIS-A hardness can be obtained without increasing the amount of carbon black. This means that the hardness can be increased without fear of a decrease in electrical insulation.

The cross-linking curve of Comparative Example 1 shows that butyl rubber cross-links well at a high temperature of 190 ° C. as in the known technique. However, it is necessary to increase the amount of carbon black, and it is necessary to worry about a decrease in electric insulation.

This embodiment of the present invention provides a sealing rubber having a small amount of eluted chlorine and a JIS-A hardness of about 90 degrees.

[0089]

[Table 1]

(Note) (1) Butyl 365 manufactured by Exxon Chemical Industry Co., Ltd. was used.

(2) SRF-LM, a furnace carbon black manufactured by Asahi Carbon Co., Ltd., was used.

(3) Iceberg manufactured by Burgess Pigment of the United States was used.

(4) Irganox 1010 manufactured by Ciba-Geigy Japan was used.

(5) Tack roll 201 manufactured by Taoka Chemical Industry Co., Ltd. was used.

(6) As a metal deactivator, 3- (N-salicyloyl) amino-1,2,2, manufactured by Asahi Denka Kogyo KK
The 4-triazole CDA-1M was used.

(7) Cresol novolak type epoxy resin manufactured by Nippon Kayaku Co., Ltd. was used.

(8) Triphenylmethane type epoxy resin manufactured by Nippon Kayaku Co., Ltd. was used.

(9) As hydrotalcite, synthetic hydrotalcite (DHT- manufactured by Kyowa Chemical Industry Co., Ltd.) is used.
4A) was used.

[0099]

[Table 2]

Examples 3 to 4 100 parts by weight of isoprene / isobutylene rubber, 1 part by weight of decamethylenedicarboxylic acid disalicyloyl hydrazide as a metal deactivator, and LSI as an epoxy resin
2.5 phenol novolak type epoxy resin for sealing
Example 3, a compound for an electrolytic capacitor containing 4.5 parts by weight of synthetic hydrotalcite as a basic carbonate and 18 parts by weight of an alkylphenol-formaldehyde resin as a cross-linking agent. In place of 2.5 parts by weight of novolak type epoxy resin,
Table 3 shows the formulation containing 2.5 parts by weight of a naphthol-modified epoxy resin for LSI encapsulation as Example 4, and the physical properties obtained by cross-linking in the same manner as in Example 1 and the test results of measuring the amount of eluted chlorine. Are shown in Table 4.

As is clear from Table 4, the amount of eluted chlorine was
Comparative Example 1 was obtained by adding decamethylene dicarboxylic acid disalicyloyl hydrazide, phenol novolak type epoxy resin, and synthetic hydrotalcite to crosslink.
It can be seen that the amount of eluted chlorine is significantly reduced as compared with.
This shows that a crosslinked rubber having a high JIS-A hardness can be obtained without increasing the amount of carbon black as in the case of Example 1 or Example 2.

This embodiment of the present invention provides a sealing rubber in which the amount of chlorine eluted from a crosslinked rubber product without using the crosslinking method according to the present invention is 1/6 to 1/9.

[0103]

[Table 3]

(Note) (1), (2), (3), (4), (5) and (9)
Are the same as (1) to (5) and (9) in (Note) in Table 1.

(6) As a metal deactivator, CDA-6 which is decamethylenedicarboxylic acid disalicyloyl hydrazide manufactured by Asahi Denka Kogyo KK was used.

(7) Cresol novolak type epoxy resin manufactured by Nippon Kayaku Co., Ltd. was used.

(8) A naphthol-modified epoxy resin manufactured by Nippon Kayaku Co., Ltd. was used.

[0108]

[Table 4]

Examples 5 to 6, Comparative Example 2 A metal deactivator was used for 100 parts by weight of a mixture of 80 parts by weight of isoprene / isobutylene rubber and 20 parts by weight of ethylene / propylene rubber containing ethylidene norbornene as a third component. 3- (N-salicyloyl) amino-1,
2 parts by weight of 2,4-triazole, 2 parts by weight of a cresol novolak type epoxy resin for LSI encapsulation as an epoxy resin, 2 parts by weight of a synthetic hydrotalcite as a basic carbonate, and alkylphenol.
The composition for an electrolytic capacitor to which 19 parts by weight of formaldehyde resin was added is shown in Table 5 as Example 5. Table 6 shows the test results obtained by measuring the physical properties and the amount of dissolved chlorine of the rubber obtained by crosslinking in the same manner as in Example 1.

Ethylene containing 70 parts by weight of isoprene / isobutylene rubber and ethylidene norbornene as the third component
For 100 parts by weight of a mixture of 30 parts by weight of propylene rubber, decamethylene dicarboxylic acid disalicyloyl hydrazide as a metal deactivator and LS as an epoxy resin
Table 5 and Table 6 show the composition and test results of Example 6 in which 2 parts by weight of a triphenylmethane type epoxy resin for sealing I and 18 parts by weight of an alkylphenol / formaldehyde resin as a crosslinking agent were added.

For comparison, from Example 5, the metal deactivator,
The composition excluding the epoxy resin and the basic carbonate is shown as Comparative Example 2.

From Examples 5 and 6, it can be seen that a sealing rubber obtained by mixing isoprene / isobutylene rubber with a small amount of eluted chlorine and ethylene / propylene rubber containing ethylidene norbornene as the third component is provided. The amount of chlorine eluted is reduced to one sixth of that of rubber products obtained by a crosslinking method using an alkylphenol-formaldehyde resin without using the method of the present invention.

By comparing Example 5 with Comparative Example 2, it can be seen that a crosslinked rubber having a high JIS-A hardness can be obtained by the crosslinking method of the present invention without increasing the amount of carbon black.

Examples 5 and 6 are intended to provide a sealing rubber which is particularly resistant to thermal deformation.

[0115]

[Table 5]

(Note) (1), (3), (4), (5), (6), (8),
(9), (10) are (1), (2),
Same as (3), (5), (6), (7), (8) and (9).

(2) EP21 manufactured by Nippon Gosei Co., Ltd. was used.

(7) is the same as (6) in (Note) in Table 3.

[0119]

[Table 6]

[0120]

According to the cross-linking method of the present invention, it is possible to produce a sealing rubber for an aluminum electrolytic capacitor with a small amount of eluted chlorine, and it is possible to adjust the hardness by appropriately adjusting the amount of carbon black used. It is possible to provide a product with high hardness.

Each of the examples of the present invention can be used favorably as a sealing rubber.

A feature of the present invention is that the amount of chlorine eluted by the electrolyte from the sealing rubber due to the crosslinking of butyl rubber with the phenol / formaldehyde resin can be extremely reduced. The product can be manufactured without fear of the influence of chlorine compounds naturally mixed as impurities from the butyl rubber raw material used and the clay, talc and carbon black used as a filler.

A further feature of the present invention is that a sealing rubber obtained by mixing ethylene-propylene rubber having ethylidene norbornene as a third component and butyl rubber and crosslinking according to the present invention is capable of softening rubber at a high temperature. The effect is to reduce the thermal deformation of the sealing rubber having a small thickness.

[Brief description of the drawings]

FIG. 1 shows crosslinking curves measured at 190 ° C. by the oscillating rheometer of Example 1 and Comparative Example 1.

Claims (17)

[Claims] 1. An alkylphenol / formaldehyde resin, a metal deactivator, an epoxy resin, a base, and a mixture of isoprene / isobutylene rubber or a mixture of ethylene / propylene rubber having isoprene / isobutylene rubber and ethylidene norbornene as a third component. A method for crosslinking isoprene / isobutylene rubber or a mixture of isoprene / isobutylene rubber and ethylene / propylene rubber having ethylidene norbornene as a third component, which is added and crosslinked by adding at least one compound selected from a basic carbonate and hydrotalcite. 2. The cross-linking method according to claim 1, wherein the cross-linking is carried out by further adding carbon black and clay as a filler. 3. The cross-linking method according to claim 1, wherein one or more of zinc oxide, stearic acid and an antioxidant are further added for cross-linking. 4. 100 parts by weight of isoprene / isobutylene rubber or 68 parts by weight of isoprene / isobutylene rubber
For 100 parts by weight of a mixture of 92 parts by weight and 32 parts by weight to 8 parts by weight of ethylene / propylene rubber containing ethylidene norbornene as a third component, 16 parts by weight to 20 parts by weight of an alkylphenol / formaldehyde resin and 0 parts by weight of a metal deactivator 0.5 to 5 parts by weight, 0.5 to 5 parts by weight of an epoxy resin, and 0.5 to 5 parts by weight of one or more compounds selected from a basic carbonate and hydrotalcite The crosslinking method according to claim 1, wherein the crosslinking is carried out. 5. 100 parts by weight of isoprene / isobutylene rubber or 68 parts by weight of isoprene / isobutylene rubber
For 100 parts by weight of a mixture of 92 parts by weight and 32 parts by weight to 8 parts by weight of ethylene / propylene rubber containing ethylidene norbornene as a third component, 16 parts by weight to 20 parts by weight of an alkylphenol / formaldehyde resin and 0 parts by weight of a metal deactivator 0.5 parts by weight to 5 parts by weight, 0.5 parts by weight to 5 parts by weight of an epoxy resin, 0.5 parts by weight to 5 parts by weight of one or more compounds selected from a basic carbonate and hydrotalcite, 30 parts by weight to 60 parts by weight of carbon black as a filler
The crosslinking method according to claim 2, wherein the crosslinking is carried out by adding 50 parts by weight to 170 parts by weight of the clay. 6. 100 parts by weight of isoprene / isobutylene rubber or 68 parts by weight of isoprene / isobutylene rubber
For 100 parts by weight of a mixture of 92 parts by weight and 32 parts by weight to 8 parts by weight of ethylene / propylene rubber containing ethylidene norbornene as a third component, 16 parts by weight to 20 parts by weight of an alkylphenol / formaldehyde resin and 0 parts by weight of a metal deactivator 0.5 parts by weight to 5 parts by weight, 0.5 parts by weight to 5 parts by weight of an epoxy resin, 0.5 parts by weight to 5 parts by weight of one or more compounds selected from a basic carbonate and hydrotalcite, and oxidation 4. The cross-linking method according to claim 3, wherein at least one of zinc, stearic acid and an antioxidant is added in an amount of not more than 5 parts by weight for cross-linking. 7. 100 parts by weight of isoprene / isobutylene rubber or 68 parts by weight of isoprene / isobutylene rubber
For 100 parts by weight of a mixture of 92 parts by weight and 32 parts by weight to 8 parts by weight of ethylene / propylene rubber containing ethylidene norbornene as a third component, 16 parts by weight to 20 parts by weight of an alkylphenol / formaldehyde resin and 0 parts by weight of a metal deactivator 0.5 parts by weight to 5 parts by weight, 0.5 parts by weight to 5 parts by weight of an epoxy resin, 0.5 parts by weight to 5 parts by weight of one or more compounds selected from a basic carbonate and hydrotalcite, 30 parts by weight to 60 parts by weight of carbon black as a filler
4. The cross-linking method according to claim 3, wherein the cross-linking is carried out by adding 50 parts by weight to 170 parts by weight of a clay and one or more kinds of zinc oxide, stearic acid, and an antioxidant, each in an amount of 5 parts by weight or less. 8. The isoprene / isobutylene rubber or the isoprene / isobutylene rubber and ethylidene norbornene according to claim 1, wherein the alkylphenol / formaldehyde resin is a compound represented by the following formula: A method of crosslinking a mixture of three components of ethylene / propylene rubber. Embedded image 9. The method according to claim 9, wherein the metal deactivator is 3- (N-salicyloyl) amino-1,2,4-triazole, 1,2,3-
One or more selected from the group consisting of benzotriazole, 1,2,3-benzotriazole sodium salt, tolyltriazole, tolyltriazoleamine salt, tolyltriazole potassium salt, and decamethylenedicarboxylic acid disalicyloylhydrazide Claim 1
7. A method for crosslinking an isoprene / isobutylene rubber or a mixture of isoprene / isobutylene rubber and ethylene / propylene rubber having ethylidene norbornene as a third component according to claim 7. 10. The epoxy resin selected from the group consisting of a phenol novolak epoxy resin, a cresol novolak epoxy resin, a triphenylmethane epoxy resin, and a naphthol-modified novolak epoxy resin.
8. The method according to claim 1, wherein the number of types is two or more.
A method for crosslinking an isoprene / isobutylene rubber or a mixture of ethylene / propylene rubber having ethylidene norbornene as a third component. 11. The basic carbonate and hydrotalcite are basic aluminum carbonate, basic magnesium carbonate,
8. One or more types selected from natural hydrotalcite and synthetic hydrotalcite.
A method for crosslinking an isoprene / isobutylene rubber or a mixture of ethylene / propylene rubber having ethylidene norbornene as a third component. 12. The epoxy resin according to claim 1, wherein the epoxy resin is a phenol novolak type epoxy resin.
A method for crosslinking an isoprene / isobutylene rubber or a mixture of isoprene / isobutylene rubber and ethylene / propylene rubber having ethylidene norbornene as a third component. 13. The epoxy resin according to claim 1, wherein the epoxy resin is a cresol novolak type epoxy resin.
A method for crosslinking an isoprene / isobutylene rubber or a mixture of isoprene / isobutylene rubber and ethylene / propylene rubber having ethylidene norbornene as a third component. 14. The epoxy resin is a triphenylmethane-type epoxy resin, wherein the third component is isoprene / isobutylene rubber or isoprene / isobutylene rubber and ethylidene norbornene according to any one of claims 1 to 7. A method of crosslinking a mixture of ethylene-propylene rubber to be used. 15. The epoxy resin according to claim 1, wherein the epoxy resin is a naphthol-modified novolak type epoxy resin.
8. A method for crosslinking a mixture of isoprene / isobutylene rubber or ethylene / propylene rubber having ethylidene norbornene as a third component according to any one of (1) to (7). 16. The epoxy resin is a triphenylmethane type epoxy resin, wherein the isoprene / isobutylene rubber or isoprene / isobutylene rubber and ethylidene norbornene as a third component are as described in any one of claims 1 to 7. A method of crosslinking a mixture of ethylene-propylene rubber to be used. 17. A cross-linking method obtained by cross-linking isoprene / isobutylene rubber or a mixture of isoprene / isobutylene rubber and ethylene / propylene rubber having ethylidene norbornene as a third component by the cross-linking method according to claim 1. Description: Crosslinked rubber products.