JPS629259B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is capable of forming a vulcanizate that has a good balance between various strengths and rubber properties and has super heat aging resistance (ethylene/C ₄ - C ₁₀ α-olefin/polyene copolymer rubber) The present invention relates to an olefin-based copolymer rubber composition of a polymeric rubber type. More specifically, the present invention provides (i) ethylene/α-olefin having a molar ratio of ethylene units to C ₄ to _{C 10} α-olefin units (ethylene/α-olefin) of about 80/20 to about 95/5; Olefin-polyene copolymer rubber (A), (ii) ethylene units and propylene units in an amount having a weight ratio (A/B) of about 55/45 to about 90/10 to the copolymer rubber (A); Ethylene-propylene copolymer rubber (B) with a molar ratio (ethylene/propylene) of about 50/50 to about 85/15 and containing no polyene component, (iii) the above rubber components (A) and (B) About 0.003 to about 0.02 mole part of organic peroxide vulcanizing agent (C) per 100 parts by weight in total of (iv) about 0.003 to about 0.02 part by mole per 100 parts by weight of rubber components (A) and (B) molar parts of a vulcanization aid (D), (v) about 0.5 to about 4 parts by weight of an antioxidant (E) based on a total of 100 parts by weight of the above rubber components (A) and (B), and as desired (vi) A super heat-aging resistant copolymer rubber characterized by containing about 20 parts by weight or less of a processing aid (F) per 100 parts by weight of the rubber components (A) and (B) in total. Regarding the composition. Conventionally, vulcanizates obtained from ethylene-propylene copolymer rubbers such as ethylene-propylene-polyene copolymer rubber and ethylene-propylene copolymer rubber have good heat aging resistance and resistance due to the structure of the rubber. It has ozone resistance, chemical resistance, electrical insulation properties, and flexibility, so it can be used, for example, in plug caps, ignition caps, and diesel engines of automobile engines that are exposed to high-temperature environments with strong mechanical vibrations. It is used in the insulation layer of viewer caps, ignition cables, parts around automobile engines such as radiator hoses, the insulation layer of marine electrical cables, and even the insulation layer of ordinary power transmission cables. However, it is desired that olefin rubbers such as ethylene-propylene copolymer rubbers be provided with further improved properties such as heat aging resistance and electrical insulation properties for these uses. For example, due to automobile exhaust gas regulations, efforts are being made to improve combustion efficiency, and due to the resulting rise in engine temperature, the temperature around the engine has become lower than before.
As a result, parts that used to be below 100℃ are now exposed to higher temperatures than before, and as a result, parts used around the engine are required to have even higher heat aging resistance. The inventors have found that vulcanizates obtained from known ethylene-propylene copolymer rubber compositions do not meet this requirement. For example, in the proposal of Japanese Patent Publication No. 49-16259, ethylene-propylene-diene copolymer rubber, mineral fillers, peroxides, and specific compounds such as quinone dioxime compounds, nitroso compounds, or nitro compounds are used. We have proposed a method for producing a vulcanized product with excellent heat aging resistance by vulcanizing a composition using a special method. However, according to the description in the publication, if left at 120°C for 7 days, the vulcanizate elongates and its strength decreases to less than 90% of its initial value, and according to the inventor's experiments, the vulcanizate was tested in an accelerated heat resistance test. In other words, if left at 160℃ for 7 days, it will elongate and its strength will drop to less than 50% of its initial value, resulting in severe deterioration. Therefore, it was not suitable for use as a part around future automobile engines. Furthermore, for example, since electric wires for ships, that is, ship electric wires, are particularly required to have flexibility due to the complicated wiring inside the ship, vulcanized products of ethylene-α-olefin copolymer rubber are suitable as the insulating layer of ship wires. However, due to the nature of ships operating at sea for long periods of time, failure of marine electrical wires cannot be tolerated, and there are particularly strict requirements regarding the durability of the insulation layer of marine electrical wires, and further improvements in durability are desired. It was rare. Furthermore, when using a vulcanized product of ethylene-propylene copolymer rubber as an insulating layer for high-voltage power transmission wires, for example, the electrical properties, mechanical strength,
A high level of heat aging resistance is required, but the reality is that it can practically withstand only a transmission voltage of about 20,000 volts at most. The reason for this is that the processability of the unvulcanized compounded rubber of ethylene/propylene copolymer rubber and the strength of the rubber vulcanizate are not well balanced in the process of manufacturing electric wires using ethylene/propylene copolymer rubber vulcanizate as the insulating layer. First, it cannot meet high standards of electrical properties, mechanical properties, and heat resistance. In other words, electric wires with an ethylene/propylene copolymer rubber vulcanizate as an insulating layer are usually produced by feeding an unvulcanized compounded rubber containing rubber, a vulcanizing agent, a processing aid, and a filler into an extruder. At the same time, the conductor wire, which is separately introduced into the extruder and becomes the current-carrying part of the wire, is coated in a cylindrical shape with compounded rubber in the extruder, and then heated in the vulcanization system, which produces even higher voltage. In order to be used as an insulating layer for electric wires, the insulating layer must have a low dielectric loss tangent in order to prevent heat generation due to dielectric loss as much as possible. To meet this requirement, it is preferable to use a compounded rubber containing a small amount of processing aids, fillers, etc. that cause an increase in dielectric loss tangent. However, due to the small amount of processing aids, the outer surface of the cylinder loses its smoothness during the extrusion process in which the compound rubber is coated in a cylindrical shape around the current-carrying part in the electric wire manufacturing process. This causes deterioration in the properties of the wire, and in fact, the loss of smoothness causes the AC breakdown voltage resistance of the insulating portion to decrease, making it impossible to use it as a high-voltage power transmission wire. On the other hand, attempts have been made to reduce the molecular weight of the ethylene/propylene copolymer rubber or to use an ethylene/propylene copolymer rubber with a wide molecular weight distribution to solve this problem in extrusion processability. Although this method certainly improves extrusion processability,
It was learned that as the molecular weight decreases or the molecular weight distribution expands, the strength of the vulcanizate, especially the stress at break, decreases, making it unusable as an insulating layer for high-voltage power transmission lines. Therefore, in any case, the conventional ethylene
As long as propylene-based copolymer rubber is used, the voltage of a power transmission wire having an insulating layer made of the vulcanized product is practically limited to about 20,000 volts. Many vulcanizates obtained from ethylene-propylene copolymer rubbers that have been proposed in the past also have other technical problems, but they all have the above-mentioned problems in common. Some of these other conventional proposals will be introduced below. For example, Japanese Patent Publication No. 46-32359 proposes a self-fusing insulating composition using ethylene-propylene copolymer rubber. In this proposal, ethylene/propylene/diene copolymer rubber
To 100 parts by weight, add 20 to 130 parts by weight of ethylene/propylene copolymer rubber, 10 parts by weight of a tackifier such as coumaron-indene resin, phenolic resin or turpentine resin with a degree of polymerization that is liquid at room temperature, etc.
A self-bonding insulating composition has been proposed in which an adjuvant is added to a matrix containing ~200 parts by weight and 0.2 to 20 parts by weight of a crosslinking agent. In this proposal, the α-olefin copolymerized with ethylene is specified as propylene, and the ethylene/C ₄ to _{C 10} α-olefin/polyene copolymer rubber (A) is essential as a rubber component in the composition of the present invention. is not mentioned at all. There is also the disadvantage that it is essential to use substantial amounts of the special tackifier resins mentioned above. Even with this proposed composition, the above-mentioned technical troubles cannot be avoided, and a vulcanizate that exhibits excellent strength and rubber properties in a well-balanced manner and exhibits satisfactory heat aging resistance cannot be provided. Its heat aging resistance is significantly inferior to that of the composition of the present invention. For example, ethylene and
A rubber composition that improves the adhesion and processability of a propylene-based copolymer rubber composition is disclosed.
No. 44018 proposes a method for producing such a rubber composition. These proposals include 1 to 40 parts by weight of ethylene/α-olefin copolymer rubber, alkylphenol formaldehyde resin or its modified product, rosin or Rosin esters or mixtures thereof 0.5
A rubber composition containing ~30 parts by weight as an essential component has been proposed. In this proposal, ethylene/propylene/
It specifies the use of non-conjugated diene copolymer rubber, and makes no mention of the use of ethylene/C ₄ -C ₁₀ α-olefin/polyene copolymer. Further, as the above-mentioned ethylene/α-olefin copolymer rubber, only ethylene/propylene copolymer is exemplified, and in all the examples, only examples of using ethylene/propylene copolymer are disclosed. Furthermore, it is stated that even if polybutene or polyisobutylene is used in place of the copolymer, a satisfactory improvement cannot be achieved. Also,
As a vulcanizing agent, only the combined use of sulfur and an organic sulfur compound is disclosed, and there is no mention of an organic peroxide vulcanizing agent. Even with this proposed composition, the above-mentioned technical troubles cannot be avoided, and a vulcanizate having excellent strength and rubber-like properties in a well-balanced manner and exhibiting a high degree of heat aging resistance cannot be provided. Furthermore, for example, Japanese Patent Publication No. 48-745
No. 11129) proposes a self-bonding semiconductive tape using ethylene-propylene copolymer rubber. In this proposal, for 100 parts by weight of ethylene/propylene/diene copolymer,
High molecular weight polyisobutylene and/or ethylene/
Propylene copolymer 50~150 parts by weight, plasticizer 5~
A base compound is prepared by adding 50 parts by weight, 5 to 50 parts by weight of a tackifier, and 50 to 150 parts by weight of carbon black. A self-fusing semiconducting tape has been proposed in which a sulfur accelerator is added, the tape is formed and then vulcanized. This proposal is also specific to the use of ethylene/propylene/diene copolymers and is completely silent regarding the use of ethylene/ _C4 - _C10 alpha-olefin/polyene copolymers. Furthermore, as mentioned above, it is specified for the use of vulcanizing agents to vulcanize only ethylene/propylene/diene copolymers, and in the case of combinations of ethylene/propylene/diene copolymers and ethylene/propylene copolymers. The use of organic peroxide vulcanizing agents that can vulcanize both is actively excluded. There is also no mention of the use of antioxidants in combination. Even with this proposed composition, the above-mentioned technical troubles cannot be avoided, and a vulcanizate that has excellent strength and rubber properties in a well-balanced manner and exhibits a high degree of heat aging resistance cannot be provided. US Pat. No. 3,725,330 is known as a proposal similar to this proposal, but it has the same technical defects as above. Furthermore, for example, Japanese Patent Publication No. 48-50299
-6718) contains 10 to 60 parts by weight of polyethylene and 5 to 40 parts by weight of polyisobutylene based on 100 parts by weight of ethylene/propylene copolymer and/or ethylene/propylene/diene copolymer, Heat-resistant self-bonding insulating tapes that do not contain fillers and are crosslinked with a crosslinking agent have been proposed. In this proposal as well, ethylene/propylene/
It specifies the use of diene copolymers, there is no mention of the use of ethylene/C ₄ - C ₁₀ α-olefin/polyene copolymer rubber, and there is no mention of the use of ethylene/propylene copolymers and ethylene/propylene/diene copolymers. No specific examples are disclosed even regarding the use of polymers in combination. Even with this proposed composition, the above-mentioned technical troubles cannot be avoided, and in particular, a vulcanizate that exhibits excellent strength and rubber properties in a well-balanced manner and exhibits high heat aging resistance cannot be provided. The present inventors have conducted research to develop a rubber composition having further improved properties that can overcome the problems of the prior art as described above. As a result, the ethylene/C ₄ to _{C 10} α-olefin/polyene copolymer rubber (A) satisfies the ethylene/α-olefin molar ratio in (i) above, and the ethylene/propylene molar ratio in (ii) above. It is composed of a combination of ethylene/propylene copolymer rubber (B) that does not contain a polyene component, that is, does not contain double bonds derived from the polyene component, and the copolymer rubber (A)/the copolymer rubber (B) The weight ratio is approximately 55/45 to approximately
an olefin-based mixed rubber component that is 90/10;
(iii) to (v), if desired, an organic peroxide vulcanizing agent (C), a vulcanization aid (D), an antioxidant (B), which also satisfies the specific amount conditions of (vi), and, if desired, It has been demonstrated that a rubber composition containing a processing aid (F), which has not been previously proposed, provides a vulcanizate that exhibits remarkable heat aging resistance, has high strength, and has excellent rubber properties. discovered. Furthermore, the vulcanizate from the olefin rubber composition that satisfies the requirements (i) to (v) of the present invention is, for example, 130
We discovered that it exhibits amazing heat aging resistance, essentially maintaining its initial physical properties even when exposed to a hot air atmosphere at ℃ for 20 days, and has a well-balanced combination of excellent high strength and rubbery properties. . Furthermore, the vulcanizate from the olefin rubber composition that fully satisfies the requirements (i) to (v) of the present invention has a relatively low molecular weight because it has the above-mentioned properties such as high strength and super heat aging resistance. Even when using the above copolymer rubbers (A) and (B), it is possible to achieve practically sufficient strength and heat aging resistance, and thus exhibit good extrusion processability when used as a wire coating material. In the conventionally proposed power transmission wire, it is possible to ensure the smoothness of the outer surface of the insulating layer and maintain satisfactory heat aging resistance against heat generation due to dielectric loss.
Although the transmission voltage was limited to about 20,000 volts at most, it was found that it can withstand long-term use as a high-voltage power transmission wire that can withstand a transmission voltage of about 70,000 volts, which is a marked improvement. Ta. Therefore, an object of the present invention is to be able to overcome the defects and disadvantages of the ethylene/propylene copolymer rubber composition and to have the above-mentioned outstanding improved properties (ethylene/C ₄ -C ₁₀ α -Olefin/
An object of the present invention is to provide an improved rubber composition based on polyene copolymer rubber)-(ethylene/propylene copolymer rubber). The above objects and many other objects and advantages of the present invention will become more apparent from the following description. One rubber component in the rubber composition of the present invention is
The molar ratio of ethylene units and C ₄ to C ₁₀ α-olefin units (ethylene/α-olefin) is approximately 80/20
- about 95/5, preferably about 85/15 - about 95/5 ethylene/α-olefin/polyene copolymer rubber (A)
It is. If the molar ratio is too small, less than about 80/20, there will be a non-negligible decline in the strength, heat aging resistance, etc. of the vulcanizate obtained, and if the molar ratio is too large, exceeding about 95/5, the resulting Since the rubbery properties of the vulcanizate deteriorate, copolymer rubber with a molar ratio within the above range is
Use (A). C ₄ to C ₁₀ α- used in forming the copolymer rubber (A)
Examples of olefins include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, and mixtures of at least two thereof. Among these, use of 1-butene is particularly preferred. Examples of the polyene component used to form the copolymer rubber (A) include 1,4-hexadiene, 1,
6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7
- Chain nonconjugated dienes such as methyl-1,6-octadiene; cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5 −
Cyclic non-conjugated dienes such as isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene; 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5 - norbornene, 2
-propenyl-2,2-norbornadiene, 1.
Examples include trienes such as 3,7-octatriene and 1,4,9-decatriene.
Among these, preferred polyenes are cyclic nonconjugated dienes and 1,4-hesadiene, especially dicyclopentadiene or 5-ethylidene-2-norbornene. The above-mentioned ethylene/α-olefin/polyene copolymer rubber (A) contains a polyene component as exemplified above, and the content in the copolymer rubber (A) is preferably about 4 to 4 when expressed in terms of iodine value. About 50, more preferably about 4 to about 40, even more preferably about 4 to about 30. The other rubber component in the rubber composition of the present invention is
Ethylene/propylene copolymer whose molar ratio of ethylene units to propylene units (ethylene/propylene) is about 50/50 to about 85/15, preferably about 55/45 to about 85/15, and which does not contain a polyene component. This is polymerized rubber (B). If the above molar ratio is too small, less than about 50/50, the strength of the vulcanizate obtained will show a non-negligible decrease;
Moreover, if the molar ratio is too large exceeding about 85/15,
Since the rubbery properties of the resulting vulcanizate deteriorate, a copolymer rubber (B) having a molar ratio within the above range is used. Since the copolymer rubber (B) does not contain a polyene component, it is a copolymer rubber component that does not contain a double bond derived from the polyene component in its molecular chain. Such copolymer rubber (B) is obtained, for example, by copolymerizing ethylene and propylene under a Ziegler catalyst, but a small amount of double bonds may be present in the molecular chain due to disproportionation reactions, etc. sell. Even in such cases, the copolymer rubber (B) usually has an iodine value of 2 or less and can be suitably used as the copolymer rubber (B) of the present invention. The intrinsic viscosity [η] of each of the copolymer rubber (A) and copolymer rubber (B) is preferably about 0.6 to about dl, expressed as a value measured by a multipoint method at 135°C in decalin. /g, more preferably about 0.8 to about 4
dl/g, more preferably about 0.3 to about 3 dl/g. If [η] is too small below the above-mentioned range, the strength of the vulcanizate will be low; if it is too large above the above-mentioned range, it will be difficult to produce the vulcanizate, for example in the roll processing step for preparing unvulcanized compounded rubber. If [η] is within the above-mentioned range, it is likely to cause problems in the production of vulcanizates, such as a decrease in roll processability and a deterioration in moldability due to a decrease in fluidity in the process of molding the compounded rubber into a desired shape. Adoption is preferred.
In particular, in the case of a composition used for insulating electric wires, it is preferable to use a copolymer rubber whose [η] is in the range of about 0.8 to about 2 dl/g. Various methods for producing copolymer rubber (A) and copolymer rubber (B) are known per se, and can be used to produce these copolymer rubbers in the composition of the present invention. Alternatively, it may be one obtained on the market. For example, using a Ziegler catalyst such as a combination of a soluble vanadium compound and an organoaluminium compound in an inert organic medium, ethylene, an α-olefin having 4 to 10 carbon atoms, optionally a polyene, and hydrogen as a molecular weight regulator are used. It can be produced by supplying gas etc. and performing a copolymerization reaction. Examples of the organic medium include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, and kerosene; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; Carbon tetrachloride, tetrachlorethylene, trichlorethylene, ethyl chloride, methylene chloride,
Halogenated hydrocarbons such as dichloroethane can be used alone or in combination. If desired, the comonomer itself can also serve as a medium. In addition, examples of the above-mentioned soluble vanadium compounds include vanadium tetrachloride, vanadyl trichloride,
Vanadium triacetylacetonate, vanadyl acetylacetonate, vanadyl trialkoxide VO(OR) ₃ (herein, R represents a hydrocarbon group, such as an alkyl group, an aryl group, etc.), halogenated vanadyl alkoxide VO(OR) _o X ₃ -n (wherein R has the same meaning as above, X represents a halogen atom, and 0<n<3) can be used alone or in combination. Furthermore, the organoaluminum compound is represented by the general formula R _n AlX ₃ -m (where R is an aliphatic hydrocarbon group such as an alkyl group, X is a halogen, and 1≦m≦3). Compounds such as triethylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride,
Ethylaluminum dichloride and the like can be used alone or in combination. In the present invention, the ethylene/α-olefin/polyene copolymer rubber (A) and the ethylene/propylene copolymer rubber (B) have a weight ratio (A/B) of about
It is used in a proportion of 55/45 to about 90/10. The weight ratio (A/B) is preferably about 60/40 to about
It's 80/20. Even if the amount ratio exceeds the above range and the copolymer rubber (A) is excessive, or the copolymer rubber (B)
Even if the amount is excessive, a vulcanizate with excellent heat aging resistance cannot be provided, so in the present invention, the copolymer rubber is adjusted to satisfy the above weight ratio (A/B) condition.
(A) and copolymer rubber (B) are used. Furthermore, in the rubber composition of the present invention, the total amount of rubber components (A) and (B) is about 25% by weight or more, more preferably about 35% by weight or more based on the weight of the composition. suitable. The rubber composition of the present invention comprises the above-mentioned two types of copolymer rubbers.
In addition to containing the rubber component consisting of (A) and (B) as an essential component, it is about 0.003 mol or more, for example about 0.003 to
Contains about 0.002 mole part of organic peroxide vulcanizing agent (C). The amount of the vulcanizing agent (C) used is preferably about 0.005 to about 0.015 parts by mole based on the above-mentioned total of 100 parts by weight. If the amount of the vulcanizing agent (C) exceeds the above range and is too small, the strength and heat aging resistance of the vulcanizate will decrease, and if it is too much, the heat aging resistance may decrease. In the invention rubber composition,
Used in the above amount range. In addition, in the rubber composition of the present invention, an organic peroxide vulcanizing agent (C) is used, but if sulfur, an organic sulfur compound, etc. are used in place of the vulcanizing agent (C), the heat aging resistance of the vulcanizate obtained becomes inferior. However, it may be possible to further improve the mechanical strength by replacing a part, especially a small part, of the vulcanizing agent (C) with sulfur. It is included in this aspect. At this time, the amount of sulfur used is determined by the organic peroxide vulcanizing agent (C).
It is best to use it in a small amount of about 1/2 mole or less per 1 mole. Examples of the above organic peroxide vulcanizing agent (C) include:
Tertiary butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, p-menthane hydroperoxide,
Alkyl hydroperoxides such as 2,5-dimethyl-2,5-dihydroperoxyhexane, 2,5-dimethyl-2,5-dihydroperoxyhexine-3; di-tert-butyl peroxide;
Di-tertiary amyl peroxide, tert-butyl mill peroxide, dicumyl peroxide, 1,4-
(or 1,3-)ditert-butylperoxyisopropylbenzene, 2,2-ditert-butylperoxybutane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl -2,5-di(tert-butylperoxy)hexyne-3, n-butyl-4,4-di-tert-butyl valerate, 1,1-di-tert-butylperoxycyclohexane, di-tert-butylperoxy-3・３・
5-trimethylhexane, 2,2-bis(4,4
-Dialkyl peroxides such as di-tert-butylperoxycyclohexyl)propane; diacetyl peroxide, dipropionyl peroxide, dioctanoyl peroxide, 3, 5, 5
- Diacyl peroxides such as trimethylhexanoyl peroxide, didecanoyl peroxide, dilauroyl peroxide, dibenzoyl peroxide, di-p-chlorobenzoyl peroxide, di-2,4-dichlorobenzoyl peroxide, succinituacid peroxide; tert-butyl Peroxy acetate, tert-butyl peroxyisobutyrate, tert-butyl peroxypivalate, tert-butyl peroxymaleic acid,
Tert-butyl peroxydecanoate, tert-butyl peroxybenzoate, di-tert-butyl diperoxy phthalate, tert-butyl peroxylaurate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butyl peroxy Peroxy esters such as isopropyl carbonate; ketone peroxides such as dicyclohexanone peroxide; and mixtures thereof. Among them, it is preferable to use organic peroxides whose temperature gives a half-life of 1 minute in the range of 130°C to 200°C, especially n-butyl-4.4-
Ditert-butyl valerate, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2.
5-di(benzoylperoxy)hexane, 2.
5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, di-tert-butyl peroxide,
1,1-ditert-butylperoxy-3,3,5-
Organic peroxides such as trimethylcyclohexane and tert-butyl hydroperoxide can be preferably used. The rubber composition of the present invention comprises the above-mentioned copolymer rubber (A),
In addition to (B) and the organic peroxide vulcanizing agent (C), about 0.003 parts by weight per 100 parts by weight of the rubber components (A) and (B)
The vulcanization aid (D) is contained in a molar or more amount, for example, about 0.003 to about 0.002 molar part, preferably about 0.005 to about 0.015 molar part. The vulcanization aid (D) is preferably used in an amount up to approximately equivalent mole to the organic peroxide vulcanization agent (C). By using a vulcanization aid (D) in addition to the vulcanizing agent (C), it is possible to improve not only the mechanical strength but also the heat resistance of the resulting vulcanizate. If the amount of vulcanization aid (D) used is too small, exceeding the above usage range, the strength and heat resistance will be poor, and if it is too much, it will not only be wasted, but in some cases, the heat resistance Since it may have an adverse effect on sex, it should be used within the above range. Examples of such vulcanization aids (D) include quinonedioxime compounds such as p-quinonedioxime and p.p'-dibenzoylquinonedioxime;
- dinitroso compounds such as dinitrosobenzene, N-methyl-N, 4-dinitrosomethylaniline; nitro compounds such as m-dinitrobenzene, 2,4-dinitrotoluene; triallylcyanurate, diallylphthalate, Allyl compounds such as diallyl itaconate and tetraallyloxyene; Methacrylic compounds such as trimethylolpraban trimethacrylate, ethylene dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and polyethylene glycol dimethacrylate; Other N. Examples include N'-phenylene bismaleimide, divinylbenzene and divinyltoluene. Among these exemplified vulcanization aids (D), p.p'-dibenzoylquinone dioxime, p-quinone dioxime, triallyl cyanurate, polyethylene glycol dimethacrylate, and the like are more preferably used. The rubber composition of the present invention comprises the above-mentioned copolymer rubber (A)
and (B), organic peroxide vulcanizing agent (C) and vulcanizing aid
In addition to (D), a total of 100% of the rubber components (A) and (B)
About 0.5 parts by weight or more, preferably about 0.5 parts by weight
It contains 0.5 to about 4 parts by weight, more preferably about 1 to about 3 parts by weight of antioxidant (E). The antioxidant (E)
If the amount used is less than about 0.5 part by weight, the heat aging resistance of the resulting vulcanizate will deteriorate, which is disadvantageous. Furthermore, even if a large amount of antioxidant is used in excess of about 4 parts by weight, no further improvement can be expected and the amount used will only be unnecessarily increased, so it is sufficient to use up to about 4 parts by weight. It is. Examples of such antioxidants (E) include styrenated phenols, 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, and 2,6-di-tert-butylphenol. Tert-butyl-p-ethylphenol, 2,4,6-tri-tert-butylphenol, butylhydroxyanisole, 1-hydroxy-3-methyl-4-isopropylbenzene,
Mono-tert-butyl-p-cresol, mono-tert-butyl-m-cresol, 2,4-dimethyl-6-tert-butylphenol, butylated bisphenol A, 2,2'-methylene-bis(4-ethyl- 6-
tert-butylphenol), 4,4'-butylidene-
Bis(3-methyl-6-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6
-tert-butylphenol), 2,2'-methylene-
Bis(4-ethyl-6-tert-butylphenol), 4,4'-methyl-bis(2,6-di-tert-butylphenol), 2,2'-methylene-bis(4-methyl-6- tertiary nonylphenol), 4.
4'-butylidene-bis(3-methyl-6-tert-butylphenol), 2,2'-isobutylidene-bis(4,6-dimethylphenol), 4,4'-thio-bis(3-methyl-6 -tert-butylphenol), bis(3-methyl-4-hydroxy-5-
tert-butylbenzyl) sulfide, 4,4'-thio-bis(2-methyl-6-tert-butylphenol), 2,2'-thio-bis(4-methyl-6-tert-butylphenol), 4・4'-Thio-bis(6
-tert-butyl-6-methylphenol), 2.2
-thio[diethyl-bis3(3,5-di-tert-butyl-4-hydroxyphenol)propionate], bis-[3,3-bis(4'-hydroxy-
3′-tert-butylphenol)-butylic acid] glycol ester, bis[2-(2-hydroxy-5-methyl-3-tert-butyl-benzyl)-4-methyl-6-tert-butyl phenyl] terephthalate, 1. 3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)isocyanute, N,N'-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxy) -hydrocinamide), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol)
Propionate, Tetrakis [methylene-3
(3,5-di-tert-butyl-4hydroxyphenyl)propionate]methane, 1,1'-bis[4
-hydroxyphenyl)cyclohexane, 2.6
-mono(α-methylbenzyl)phenol, di(α-methylbenzyl)phenol, tri(α-
methylbenzyl)phenol, bis(2'-hydroxy-3'-tert-butyl-5'-methylbenzyl)4
-Methyl-phenol, 2,5-di-tert-amylhydroquinone, 2,6-di-tert-butyl-α-
Dimethylamino-p-cresol, 2,5-di-
Phenolic antioxidants such as tert-butylhydroquinone, diethyl ester of 3,5-di-tert-butyl-4-hydroxybenzyl phosphate, catechol, hydroquinone, etc.; 2-mercaptobenzimidazole, zinc of 2-mercaptobenzimidazole Benzimidazole antioxidants such as salts, 2-mercaptomethylbenzimidazole, zinc salts of 2-mercaptomethylbenzimidazole; dimyristylthiodipropioate, dilaurylthiodipropionate, distearylthiodipropionate, ditridecyl Aliphatic thioether antioxidants such as thiodipropionate;
Metal salt-based oxidation of dithiocarbamic acid such as zinc or nickel salt of dibutyldithiocarbamic acid, zinc salt of diethyldithiocarbamic acid, zinc salt of ethyl-phenyl-dithiocarbamic acid, zinc salt of dimethyldithiocarbamic acid, zinc salt of diamyldithiocarbamic acid, etc. Inhibitor: 2,2,4-trimethyl-1,2-dihydroquinoline or its polymer, 6-ethoxy-2,2,4-trimethyl-
Quinoline antioxidants such as 1,2-dihydroquinoline; other phenothiazine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, bis(2,2,6,6-tetramethyl-
Examples include 4-piperidine) sebacate and N-(3'-hydroxybutylidene)-1-naphthylamine. These exemplified antioxidants (E)
Among them, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 2-mercaptobenzimidazole, 2-mercaptobenzimidazole zinc salt, nickel dibutylthiocarbamate salt,
Mono(α-methylbenzyl)phenol, di(α
-methylbenzyl)phenol, tri(α-methylbenzyl)phenol, 2,6-di-tert-butyl-4-methylphenol, N-(3'-hydroxybutylidene)-naphthylamine, and a combination of at least two of these can be preferably exemplified. The (ethylene/C ₄ - C ₁₀ α-olefin/polyene copolymer rubber)-(ethylene/propylene copolymer rubber) rubber composition of the present invention comprises the above-mentioned copolymer rubbers (A) and (B), an organic In addition to the peroxide vulcanizing agent (C), vulcanizing aid (D) and antioxidant (E), if desired, approximately 20 parts by weight per 100 parts by weight of the above rubber components (A) and (B) in total. parts, preferably about 15 parts by weight or less, of processing aids. The use of excessive amounts of processing aids in excess of about 20 parts by weight will reduce the heat aging resistance of the resulting vulcanizate and should therefore be limited to a maximum of about 20 parts by weight. Examples of such processing aids for improving the processing suitability of the rubber composition include softeners, tackifiers, plasticizers, and the like. Specific examples of such processing aids include process oils, lubricating oils, paraffins, liquid paraffins, petroleum-based softeners and plasticizers such as vaseline; atactic polypropylene;
Examples include synthetic polymeric softeners and plasticizers such as liquid polybutene. Among such processing aids, it is preferable to use, for example, paraffinic process oil, liquid paraffins, liquid polybutene, and the like. The (ethylene/C ₄ to C ₁₀ α-olefin/polyene copolymer rubber)-(ethylene/propylene copolymer rubber) rubber composition of the present invention may optionally contain
Furthermore, other additives may be included. Examples of such other additives include forming aids, fillers or pigments, blowing agents, and other customary additives. Examples of the molding aids include ricinoleic acid, stearic acid, palmitic acid, lauric acid, barium stearate, calcium stearate, zinc stearate, esters of the above acids, higher fatty acids, their salts, and their esters. For example, these can be used alone or in combination. The amount of these molding aids to be used can be selected as appropriate, but preferably about 10 parts by weight per 100 parts by weight of the copolymer rubber components (A) and (B).
Amounts of up to parts by weight may be utilized, more preferably from about 1 to 5 parts by weight. Preferred examples of the filler or pigment include inorganic fillers or pigments such as finely divided silicic acid or silicates, calcium carbonate, talc, clay, and carbon black. The blending amount of such fillers can also be selected as appropriate; for example, the amount used can be up to about 200 parts by weight per 100 parts by weight of the copolymer rubber components (A) and (B). . Preferably, amounts up to about 180 parts by weight may be utilized. If used in an excessive amount exceeding about 200 parts by weight, the rubber properties of the resulting vulcanizate may deteriorate, such as a decrease in flexibility, so the surface hardness, tensile strength, etc. of the vulcanizate may deteriorate. It is preferable to use the amount that can improve the performance, for example, the amount used as exemplified above. The amount of these fillers to be used can be changed as appropriate depending on the type of filler to be used, the intended use of the rubber composition, and the like. For example, in the case of a rubber composition used as an insulating layer for high-voltage power transmission wires, it is preferably about 50% by weight or less, more preferably about An example of the amount used is 30% by weight or less. Generally, the desired volume resistivity of electrically insulating materials is approximately 10 ¹² Ω・cm or more, and therefore, when carbon black, which has electrical conductivity, is unavoidably used, the above-mentioned total resistance is
Preferably, less than about 15 parts by weight per 100 parts by weight are utilized. Furthermore, as other additives, a foaming agent, a foaming aid, etc. can also be blended for the purpose of forming a foam. Examples of such blowing agents include inorganic blowing agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, ammonium nitrite; N.N'-dimethyl N.N'-dinitroso terephthalamide; Nitroso compounds such as N′-dinitroso pentamethylene tetramine; azo compounds such as azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, azodiaminobenzene, barium azodicarboxylate; benzene sulfonyl hydrazide, Toluene sulfonyl hydrazide, p・p′-oxybis(benzenesulfonyl hydrazide), diphenylsulfone-3・
Sulfonyl hydrazide compounds such as 3'-disulfonyl hydrazide; calcium azide, 4.
Azide compounds such as 4'-diphenyl disulfonyl azide, para-toluene, malhonyl azide;
can be mentioned. Among them, nitro compounds,
Azo and azide compounds are preferably used. The amount used can be selected as appropriate, for example, from about 0.5 to about 30 parts by weight per 100 parts by weight of the rubber components (A) and (B). The (ethylene/C ₄ - C ₁₀ α-olefin/polyene copolymer rubber)-(ethylene/propylene copolymer rubber) rubber composition of the present invention can be an uncured (unvulcanized) composition. However, the composition can also be in the form of a cured (vulcanized) molded article. The means for preparing such uncured or cured compositions are well known per se, and can be similarly carried out in the present invention. For example, to obtain electrical insulation for plug caps, ignition caps, distributor caps, etc. around automobile engines, mixers such as a Banbury mixer are used to heat the insulators at about 90°C to about 150°C, e.g. After kneading copolymer rubber A, copolymer rubber B, inorganic fillers, and processing aids as necessary for about 10 minutes, use rolls such as open rolls to adjust the roll temperature to about 40 to about 80. antioxidants at temperatures that do not result in substantial vulcanization, such as °C.
Add organic peroxide and vulcanization aid, etc.
For example, a compounded rubber in the form of a sheet or ribbon is prepared. This compounded rubber is molded into the shape of the above caps using, for example, an extrusion molding machine, and heated to a vulcanization temperature at the same time as molding, or after molding, the molded product is vulcanized at a temperature of, for example, about 130° to about 220°C. Vulcanization is performed by heating in a tank for, for example, about 1 minute to about 60 minutes, or by heating the compounded rubber at the temperature and for the time at the same time as molding using a hot press, to produce the above caps. I can do it. For example, in the case of forming an insulating vulcanized layer that covers the current-carrying part of an electric wire in a cylindrical shape, for example, a sheet-like or ribbon-like compounded rubber prepared in the same manner as in the above-mentioned embodiments is used, for example, at a rate of about 90% or about
The conductive wire of the current-carrying part introduced into the extruder is separately extruded and coated into a cylindrical shape, and then the integrated conductive wire part and insulating part are heated to about 180° C. with steam. The above-mentioned insulating layer can be formed by continuously introducing the material into a vulcanization bath heated to from about 220° C. to about 0.5 to about 10 minutes, for example. EXAMPLES Hereinafter, several embodiments of the present invention will be explained in more detail using Examples together with Comparative Examples. Copolymer rubber used in Examples and Comparative Examples: Copolymer Rubber A used in Examples and Comparative Examples
Table 1 shows a list of (A ₁ to _{A 3} ) and copolymer rubber B (B ₁ .B ₂ ). Incidentally, in all the copolymer rubbers, ethylidenerubornene was used as the diolefin.

[Table] Examples 1 to 3, Comparative Examples 1 to 4 Copolymer rubber A ₁ and copolymer rubber B ₁ in Table 1 were used in the proportions listed in Table 3, and according to the formulation table in Table 2. After producing the compounded rubber, a vulcanizate was obtained. Namely, copolymer rubber A ₁ , copolymer rubber B ₁ , zinc white, stearic acid, Mistron vapor talc, Sheest S
and iodoplast P according to the combination table in Table 2,
After kneading for 6 minutes using a 4.3 Banbury mixer (OOC type, manufactured by Kobe Steel, Ltd.), antioxidant, vulcanizing agent and vulcanizing aid were added, and the roll temperature was 40°C using an 8 x 20 inch open roll. After kneading for 15 minutes at
Processed under pressure 150Kg/ ^cm2 for 30 minutes, 12cm x 14cm
A sheet-like vulcanizate with a size of 2 mm was obtained. From this vulcanizate, we punched out No. 3 dumbbells in accordance with JIS K6301.
Tensile speed 500 by method according to JIS K6301
mm/min, stress at break at break at 25°C TB ₁
(Kg/cm ² ) and elongation at break EB ₁ (%) were measured. Furthermore, according to JIS K6301, the hardness of the vulcanizate is HS ₁ (JISA)
was measured. These values are shown in Table 3 as initial physical properties. Next, use Toyo Seiki's "TEST TUBE AGING TESTER" to test the size 3 dumbbell mentioned above to 170
℃ for 7 days and 130℃ for 20 days under air atmosphere, each dumbbell was subjected to the same method as above to determine the stress at break TB ₂ (Kg/cm ² ) and elongation at break EB ₂
(%), hardness HS ₂ was measured. △TB, △EB, △HS
was calculated using the following formula and used as a measure of heat resistance. △TB (%) = TB ₂ - TB ₁ / TB ₁ × 100, △EB (%) = EB ₂ - EB ₁ / EB ₁ × 100, △HS = HS ₂ - HS ₁

【table】

[Table] In addition, samples were taken from the sheet-like vulcanizate,
Volume resistivity (DC500V-1) according to ASTM D257
minute value), high pressure Schering Bridge method (1000V)
The dielectric constant, dielectric loss tangent, or AC breakdown voltage was measured according to JIS K6911. Table 3 shows the above results.
It was shown to.

【table】

[Table] Examples 4 to 6 Copolymer rubber A and copolymer rubber B in Example 2
The same operations as in Example 2 were carried out, except that each copolymer rubber listed in Table 4 was used instead. The results are shown in Table 4.

[Table] Examples 7 to 13, Comparative Examples 5 and 6 In Example 2, the type and amount of antioxidant, the type and amount of vulcanizing agent, and the type and amount of vulcanization aid are listed in Table 5. The same operations were performed except for the following changes. The results are shown in Table 5. In addition, Comparative Example 5 is an example in which the amount of the antioxidant is blended is small, and Comparative Example 6 is an example in which the blended amount of the vulcanization aid is small. Comparative Example 7 An experiment was conducted in which a large amount of processing aid was added. That is, in Example 7, 30 parts by weight of paraline process oil (trade name: Diana White Process WP75; Idemitsu Kosan) was further blended, and the other operations were the same as in Example 7. The results are shown in Table 5.

[Table] Comparative Example 8 The same operation as in Example 2 was performed except that sulfur was used instead of the organic peroxide as the vulcanizing agent in Example 2 and a compounded rubber was prepared according to the formulation table in Table 6. , I got the following results. Initial physical properties TB=205Kg/cm ² EB=520% HS=85 Heat resistance test △TE=-55% (170℃ 7 days) △EB=-65% △HS=+11

【table】

[Table] Example 14 The same operation as in Example 2 was performed except that Miratron vapor talc was not mixed and the amount of Sheest S was changed to 70 parts by weight. The results were as follows. Initial physical properties TB 150Kg/cm ² EB 520% HS 83 Heat aging test △TB -2% (170°C, 7 days) △EB -5% △HS +3 From the above Examples and Comparative Examples, It is clear that the resulting vulcanizate has significantly superior heat aging resistance.

Claims (1)

[Claims] 1 (i) Ethylene/α-olefin with a molar ratio of ethylene units to C ₄ to _{C 10} α-olefin units (ethylene/α-olefin) of about 80/20 to about 95/5. - Polyene copolymer rubber (A), (ii) moles of ethylene units and propylene units in an amount such that the weight ratio (A/B) to the copolymer rubber (A) is from about 55/45 to about 90/10. Ethylene-propylene copolymer rubber (B) having a ratio (ethylene/propylene) of about 50/50 to about 85/15 and containing no polyene component; (iii) the above rubber components (A) and (B); about 0.003 to about 0.02 parts by mole of organic peroxide vulcanizing agent (C) per 100 parts by weight in total, (iv) about 0.003 to about 0.02 parts by mole per 100 parts by weight in total of the above rubber components (A) and (B); Contains molar parts of a vulcanization aid (D), and (v) about 0.5 to about 4 parts by weight of an antioxidant (E) based on a total of 100 parts by weight of the above rubber components (A) and (B). A super heat aging resistant rubber composition characterized by: