JPS629258B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention can form a vulcanizate that has a good balance of various strengths and rubber properties and has super heat aging resistance (ethylene/C ₄ -C ₁₀ α-olefin/polyene copolymer rubber) - (ethylene/C ₄ -C ₁₀ α-olefin copolymer rubber)-based olefin rubber composition. More specifically, the present invention provides (i) an 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 to 20 to about 95/5; Olefin/polyene copolymer rubber (A), (ii) ethylene units and C ₄ to The molar ratio of _C10 to α-olefin units (ethylene/α-olefin) is approximately 80/20 to approximately
Ethylene/α-olefin copolymer rubber (B) which is 95/5 and does not contain a polyene component, (iii) about 0.003 to about 100 parts by weight of the above rubber components (A) and (B) in total 0.02 mole part of organic peroxide vulcanizing agent (C), (iv) about 0.003 to about 0.02 mole part of vulcanization aid (D) based on 100 parts by weight of the above rubber components (A) and (B); (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, if desired, (vi) the above rubber component (A). The present invention relates to a super heat-aging resistant rubber composition characterized in that it contains about 20 parts by weight or less of a processing aid (F) based on a total of 100 parts by weight of (B) and (B). 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 tank 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, when left at 120°C for 7 days, both elongation and strength decrease to 90% or less of their initial values, and according to the inventor's experiments, the vulcanizate was tested in an accelerated heat resistance test. In other words, if it is left at 160℃ for 7 days, it will elongate, its strength will drop to less than 50% of its initial value, and the degree of aging will be severe.
It is impossible to maintain the original flexibility and strength of ethylene-propylene rubber vulcanizate at high temperatures of 100℃ or higher for a long period of time, and therefore it is not suitable for use as parts around future automobile engines. Ta. 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, a vulcanized product of ethylene-α-olefin copolymer rubber is suitable as an insulating layer for marine electric 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. As a result, the insulation part's AC breakdown voltage is reduced, and it cannot be used 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, 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. I learned that I couldn't stand it. Therefore, in any case, as long as conventional ethylene/propylene copolymer rubber is used,
Practically speaking, the voltage of a power transmission wire having an insulating layer made of the vulcanizate is approximately 20,000 volts. 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 - _{C 10} α-olefin/polyene copolymer rubber (A) satisfying the ethylene/α-olefin molar ratio in (i) above, and the ethylene/C ₄ -C ₁₀ α in (ii) above. - Ethylene that satisfies the olefin molar ratio and does not contain a polyene component, that is, does not contain double bonds derived from a polyene component;
C ₄ to C ₁₀ α-olefin copolymer rubber (B), said copolymer rubber (A) / said copolymer rubber (B)
an olefin-based mixed rubber component having a weight ratio of about 55/45 to about 90/10, and an organic peroxide vulcanizing agent satisfying the specified amount conditions of (iii) to (v) and, optionally, (vi) above. (C), a vulcanization aid (D), an antioxidant (E), and, if desired, a processing aid (F), which has never been proposed before. It has been discovered that the vulcanizate exhibits resistance to heat aging and provides high strength and excellent rubbery properties. Furthermore, the vulcanizate from the olefin rubber composition that satisfies the requirements (i) to (v) of the present invention is, for example, 130
It was 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 rubber-like properties. did. Furthermore, the vulcanizate obtained from the olefin rubber composition that 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/
Polyene copolymer rubber) - (ethylene/C ₄ - _{C 10} α-
An object of the present invention is to provide an improved rubber composition based on olefin copolymer rubber. The above objects and many other objects and advantages of the present invention will become more apparent from the following description. One of the rubber components in the rubber composition of the present invention has a molar ratio of ethylene units to C ₄ to _{C 10} α-olefin units (ethylene/α-olefin) of about 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.
In the rubber compositions specified in the present invention, the use of propylene cannot be used in the compositions of the present invention because the resulting vulcanizate is inferior in strength and flexibility. 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-functional 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-hexadiene, 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. It is 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
The molar ratio of ethylene units and C ₄ to _{C 10} α-olefin units (ethylene/α-olefin) is approximately 80/
The ethylene/α-olefin copolymer rubber (B) has a ratio of 20 to about 95/5, preferably about 85/15 to about 95/5, and does not contain a polyene component. If the molar ratio is too small, less than about 80 to 20, the resulting vulcanizate will have a non-negligible decrease in strength and heat resistance; if the molar ratio is too large, exceeding about 95/5, the resulting vulcanizate will Since the rubber properties of the sulfur are deteriorated, a copolymer rubber (B) having a molar ratio within the above range is used. C ₄ to C ₁₀ α- used in forming the copolymer rubber (B)
Examples of olefins and preferred α-olefins include the same α-olefins as described for the above copolymer rubber (A).
- Olefin can be exemplified, and the above copolymer rubber
The use of propylene is excluded for the same reasons stated for (A). 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) can be obtained, for example, by combining ethylene and C ₄ to _{C 10} α-olefins under a Ziegler catalyst, but a small amount of double bonds may be formed in the molecular chain due to a heterogeneous reaction. It is possible that it exists. Even in such a case, the copolymer rubber (B) usually has an iodine value of 2 or less and can be suitably used as the copolymer rubber ₅ of the present invention. The intrinsic viscosity (η) of each of the above copolymer rubber (A) and copolymer rubber (B) is preferably about 0.6 to about 6 dl, expressed as a value measured by a multi-point method at 135°C in decalin. /g, more preferably about 0.8 to about 4
dl/g, more preferably about 0.8 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. 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, and optionally a polyene,
Furthermore, it can be produced by supplying hydrogen gas or the like as a molecular weight regulator and carrying out 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; Halogenated hydrocarbons such as carbon chloride, tetrachlorethylene, trichlorethylene, ethyl chloride, methylene chloride, and 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-o
(Here, R has the same meaning as described above, X represents a halogen atom, and 0<n<3), etc., can be used alone or in combination. Furthermore, the organoaluminum compound has the general formula R _n AlX _3-n (where R is an aliphatic hydrocarbon group, such as an alkyl group, and X is a halogen;
Further, 1≦m≦3. ) For example, triethylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, etc. can be used alone or in combination. In the present invention, the above ethylene/α-olefin/polyene copolymer rubber (A) and the above ethylene/α-olefin/polyene copolymer rubber (A)
The olefin copolymer rubber (B) is used in a weight ratio (A/B) of about 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) or copolymer rubber (B) becomes excessive, a vulcanizate with excellent heat aging resistance cannot be provided. In the present invention, the copolymer rubber (A) is
and copolymer rubber (B). Furthermore, in the rubber composition of the present invention, the rubber component is
Suitably, the total amount of (A) and (B) is about 25% by weight or more, more preferably about 35% by weight or more. 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 parts by mole or more, for example about 0.003 parts by mole or more, based on the total of 100 parts by weight of the rubber components (A) and (B).
Contains ~0.02 mole parts 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 will 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 is 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-butylcumyl 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・
Dialkyl peroxides such as 5-trimethylcyclohexane, 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane; diacetyl peroxide, dipropionyl peroxide, dioctanoyl peroxide, 3.
5,5-trimethylhexanoyl peroxide,
Diacyl peroxides such as didecanoyl peroxide, dilauroyl peroxide, stearoyl peroxide, dibensoyl peroxide, di-p-chlorobenzoyl peroxide, di-2,4-dichlorobenzoyl peroxide, succinitus acid peroxide; tert-butyl peroxyacetate , tert-butyl peroxyisobutyrate, tert-butyl peroxypivalate, tert-butyl peroxymalate, tert-butyl peroxyneodecanoate, tert-butyl peroxybenzoate, di-tert-butyl diperoxyphthalate, tert-butyl Peroxylaurate, 2.5
Examples include peroxy esters such as -dimethyl-2,5-di(benzoylperoxy)hexane and tert-butylperoxyisopropyl carbonate; ketone peroxides such as dicyclohexanone peroxide; and mixtures thereof. Among them, the temperature that gives a half-life of 1 minute is
The use of organic peroxides in the range 130°C to 200°C is preferred, especially n-butyl-4,4-ditert-butylvalerate, 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, ditert-butyl peroxide, 1.1
Organic peroxides such as -di-tert-butylperoxy-3,3,5-trimethylcyclohexane and tert-butylhydroperoxy 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 0.02 mole part, preferably about 0.005 to about 0.015 mole 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, not only will it be wasted, but in some cases, the heat resistance will deteriorate. 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 tetraallyloxyethane; 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), the total of the rubber components (A) and (B)
About 0.5 parts by weight or more, preferably about 0.5 to about 4 parts by weight, more preferably about 1 to about 3 parts by weight per 100 parts by weight.
Contains parts by weight of antioxidant (E). The antioxidant
If the amount of (E) used is too small, 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-3-methylphenol), 2.2
-thio[diethyl-bis3(3,5-tert-butyl-4-hydroxyphenol)propionate], bis-[3,3-bis(4'-hydroxy-
1・3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)isocyanurate, 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 salt of 2-mercaptobenzole , 2-mercaptomethylbenzimidazole, benzimidazole-based antioxidants such as zinc salts of 2-mercaptomethylbenzimidazole;
Aliphatic thioether antioxidants such as dimyristylthiodipropionate, dilaurylthiodipropionate, distearylthiodipropionate, ditridecylthiodipropionate; zinc or nickel salt of dibutiocarbamic acid, diethyldithiocarbamic acid Antioxidants based on metal salts of dithiocarbamic acid such as zinc salt of ethyl-phenyl-dithiocarbamic acid, zinc salt of dimethyldithiocarbamic acid, zinc salt of diamyldithiocarbamic acid; 2,2,4-trimethyl-
1,2-dihydroquinoline or its polymer, 6-
Quinoline antioxidants such as ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline; others such as phenothiazine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine,
Examples include bis(2,2,6,6-tetramethyl-4-piperidine) sebacate and N-(3'-hydroxybutylidene)-1-naphthylamine. Among these exemplified antioxidants (E), 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 2-mercaptobenzimidazole, 2-mercaptobenzimidazole zinc salt, dibutyldithiocarbamic acid nickel salt, monomer (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. (Ethylene/C ₄ - C ₁₀ α-olefin/polyene copolymer rubber) of the present invention - (ethylene/C ₄ - _{C 10}
The rubber composition based on α-olefin copolymer rubber is
In addition to the above-mentioned copolymer rubbers (A) and (B), organic peroxide vulcanizing agent (C), vulcanization aid (D) and antioxidant (E), the above-mentioned rubber component (A) and (B) total
It may contain up to about 20 parts by weight, preferably up to about 15 parts by weight, of processing aids per 100 parts by weight. 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. (Ethylene/C ₄ - C ₁₀ α-olefin/polyene copolymer rubber) of the present invention - (ethylene/C ₄ - _{C 10}
The rubber composition based on α-olefin copolymer rubber is
Other additives can be further included if desired. 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. 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, more preferably from about 1 to about 5 parts by weight, can be utilized. 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 of more than about 200 parts by weight, the rubber properties of the resulting vulcanizate may deteriorate, such as a decrease in flexibility, so the surface hardness and tensile strength of the vulcanizate may deteriorate. It is preferable to use the amount that provides the above improvement, 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 about 10 ¹² Ω・cm or more, so when carbon black, which has unavoidable electrical conductivity, is used, the total resistance of the above 100
Preferably, less than about 15 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 disursunyl azide, para-toluene, malhonyl azide;
can be mentioned. Among them, nitroso compounds, azo compounds and azide compounds are preferably used. The amount used is also, for example, rubber components (A) and (B).
It can be used in an appropriate amount of about 0.5 to about 30 parts by weight per 100 parts by weight in total. (Ethylene/C ₄ - C ₁₀ α-olefin/polyene copolymer rubber) of the present invention - (ethylene/C ₄ - _{C 10}
The rubber composition based on α-olefin copolymer rubber is
can be an uncured (unvulcanized) composition;
Furthermore, the composition can 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 insulators for plug caps, ignition caps, distributor caps, etc. around automobile engines, mixers such as a Banbury mixer are used to produce electrical insulators at approximately 90°C.
After kneading copolymer rubber A, copolymer rubber B, inorganic filler, processing aids, etc. at a temperature of from about 150°C to about 150°C for about 4 to about 10 minutes,
Using rolls such as open rolls, an antioxidant, an organic peroxide, a vulcanization aid, etc. are additionally mixed at a roll temperature of about 40 to about 80°C, which does not cause substantial vulcanization. Prepare compound rubber in the form of sheets or ribbons. This compounded rubber is molded into the shape of the above-mentioned 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 heated to about 130°C.
By heating in a vulcanization tank heated to 220 to 220°C for, for example, 1 minute to 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. The above-mentioned caps can be manufactured by carrying out sulfurization. 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 exemplary embodiment is mixed with about 90% or about
The conductive wire of the current-carrying part, which was separately introduced into the extruder, is extruded into a cylindrical shape and coated, and then the integrated conductive wire part and insulating part are heated to about 180° C. or more by steam. The above-mentioned insulating layer can be formed by continuously introducing the material into a vulcanization bath heated to about 220° C. and heating it for, for example, about 0.5 to about 10 minutes. 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: 1 Copolymer Rubber A used in Examples and Comparative Examples
A list of (A ₁ to _{A 6} ) and copolymer rubber B (B ₁ to _{B 3} ) is shown in Table 1 below. Note that 1-butene was used as the α-olefin. Further, as the diolefin in copolymer rubber A, ethylidene norbornene was used.

[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, 112cm x 14cm
A sheet-like vulcanizate with a size of 2 mm was obtained. From this vulcanizate, a No. 3 dumbbell according to JIS K 6301 is punched out.
Tensile speed 500 by method according to JIS K 6301
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 K 6301, the hardness of the vulcanizate is HS ₁ (JIS
A) was measured. These values are shown in Table 3 as initial physical properties. Next, the above No. 3 dumbbell was tested using "TEST TUBE AGING TESTER" manufactured by Toyo Seiki. The test was carried out after 7 days of exposure to a temperature of 170°C in an air atmosphere and to a temperature of 130°C.
The test was performed on a sample (No. 3 dumbbell) after being exposed for 20 days in an air atmosphere. For each dumbbell, the stress at break TB ₂ (Kg/cm ² ),
Elongation at break EB ₂ (%) and hardness HB ₂ were measured. △
TB, △EB, and HS were calculated using the following formulas and were used as a guideline for heat aging 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 according to ASTMD 257 (DC500V-1
minute value), high pressure Schering Bridge method (1000V)
The dielectric constant, dielectric loss tangent, and AC breakdown voltage were measured according to JIS K 6911. Separately, the unvulcanized blended sheet was fed to a 50 mmφ extruder (L/D = 10, compression ratio = 6, Garvey die), and the appearance of the surface of the resulting strand was observed at an extrusion temperature of 105°C and a rotation speed of 40 rpm. As an index of extrusion processability, the extrusion texture was evaluated in five stages. 5... No surface unevenness at all, good gloss 4... Almost no surface unevenness, no gloss 3... Slight surface unevenness, no gloss 2... Surface unevenness, no gloss 1... Surface There were large irregularities and no gloss at all.The above results are shown in Table 3.

【table】

[Table] Examples 4 and 5 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 6 to 12, 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 2, 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 2. 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=240Kg/cm ³ EB=530% HS=87 Heat aging test (170℃, 7 days) △TB=-51% △EB=-60% △HS=+10

【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=155Kg/cm ² EB 530% HS 89 Heat aging test (170℃, 7 days) △TB-2% △EB-6% △HS +3 From the above examples and comparative examples, from the composition of the present invention It is clear that the obtained vulcanizate has extremely excellent 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) ethylene units and C ₄ to _{C 10} in an amount whose weight ratio (A/B) to the copolymer rubber (A) is about 55/45 to about 90/10. The molar ratio of α-olefin units (ethylene/α-olefin) is approximately 80/20 to approximately
Ethylene/α-olefin copolymer rubber (B) which is 95/5 and does not contain a polyene component, (iii) about 0.003 to about 100 parts by weight of the above rubber components (A) and (B) in total 0.02 mole part of organic peroxide vulcanizing agent (C), (iv) about 0.003 to about 0.02 mole part of vulcanization aid (D) based on 100 parts by weight of the above rubber components (A) and (B); and (v) an antioxidant (E) in an amount of about 0.5 to about 4 parts by weight based on a total of 100 parts by weight of the rubber components (A) and (B). rubber composition.