DE69709843T2 - Ethylene copolymer elastomer composition - Google Patents

Description

BACKGROUND OF THE INVENTION

The invention relates to an ethylene copolymer rubber composition, particularly to an ethylene copolymer rubber composition having excellent processing properties which have been a problem for an ethylene copolymer rubber prepared with a metallocene catalyst, which also has an excellent balance of processing properties and mechanical and low temperature properties. It also relates to an ethylene copolymer rubber composition in which a conjugated diene rubber is blended with the above-mentioned ethylene copolymer rubber, which has excellent processing properties and excellent co-vulcanizability with the conjugated diene rubber.

Ethylene/α-olefin/non-conjugated diene copolymers have excellent weather resistance, heat resistance, cold resistance and ozone resistance and have been widely used in building materials, automobile parts and wire covering materials.

Furthermore, in recent years, many proposals have been made for the preparation of an ethylene/α-olefin/non-conjugated diene copolymer obtained by means of a metallocene catalyst. The metallocene catalyst has an excellent copolymerization ability for comonomers such as ethylene, an α-olefin and a non-conjugated diene, and exhibits a property that the molecular weight distribution of a polymer obtained is narrow and the composition distribution is uniform; and it also exhibits a property that even comonomers (for example, long-chain α-olefins) obtained with a vanadium catalyst, which is a conventional polymerization catalyst for the production of an ethylene/α-olefin/non-conjugated diene copolymer, which were difficult to polymerize, can be easily polymerized.

For example, in Japanese Patent JP-B-5('93)-80,493, a slightly crystalline ethylenic random copolymer is proposed in which the content of the ethylene, the α-olefin having 3 to 10 carbon atoms and the non-conjugated diene is indicated, and also the intrinsic viscosity, the molecular weight distribution (Mw/Mn), the crystallinity, the B value relevant to the mole fraction of the α-olefin-ethylene chain and the amount of the portion soluble in boiling methyl acetate are indicated, and neither an αβ signal nor a βγ signal relating to the methylene chain between two adjacent tertiary carbon atoms was observed in the ¹³C-NNR spectrum.

As for vulcanized rubber obtained from the above copolymer, mechanical properties such as modulus, tensile strength, elongation at break and hardness were investigated; however, internal properties of the ethylene/α-olefin/non-conjugated diene copolymer including processing properties and low temperature properties were not investigated together in addition to the above mechanical properties.

Furthermore, the inventors of this application recently proposed in Japanese Patent Publication JP-A-2('90)-51512 a method for improving the co-vulcanizability of an ethylene/α-olefin/non-conjugated diene copolymer rubber with a conjugated diene rubber by using a straight-chain non-conjugated diene, a representative compound thereof including 7-methyl-1,6-octadiene, and the method has a higher vulcanization rate than in the case of using 5-ethylidene-2-norbornene. In Japanese Patent Publication JP-A--5('93)-262827 it is disclosed that an ethylene/α-olefin/7-methyl-1,6-octadiene copolymer rubber obtained by means of a metallocene catalyst has excellent low temperature properties, and in Japanese Patent Publication JP-A-6-128427 it is disclosed that a blend composition of a conjugated diene rubber with an ethylene/α-olefin/7-methyl-1,6-octadiene copolymer obtained by means of a metallocene catalyst has improved co-vulcanizability.

Actually, the ethylene/α-olefin/non-conjugated diene copolymer and the conjugated diene rubber originally have inferior compatibility with each other, and the ethylene/α-olefin/non-conjugated diene copolymer obtained by means of a metallocene catalyst has a narrow molecular weight distribution and thus has a disadvantage that it shows inferior processability. Therefore, when kneaded by means of a Banbury mixer, it does not mix well with the conjugated diene rubber. Thus, a rubber composition containing the conventional ethylene/α-olefin/non-conjugated diene copolymer is not sufficiently satisfactory in terms of processability.

On the other hand, a method of combining a low molecular weight copolymer with a high molecular weight copolymer whose composition is different from that of the low molecular weight copolymer is considered as a method for improving the processing properties of a polymer obtained by means of a metallocene catalyst, and as a specific example thereof, there can be mentioned a multi-stage method in which several reactors for producing the copolymer are connected in series and the polymerization is carried out continuously, and a method in which at least two catalysts differing in reactivity are introduced into one reactor. However, these methods have the problem that productivity is low, resulting in an increase in cost, and that controlling the polymerization is difficult. Therefore, it cannot be said that the above processes can be recommended for use in industry.

European Patent Specification EP-A-0718325 discloses a process for producing an ethylene/α-olefin/non-conjugated polyene random copolymer. Ethylene, α-olefin having three or more carbon atoms and a non-conjugated polyene are polymerized in the presence of a metallocene catalyst containing a specific metallocene compound. The ethylene/α-olefin/non-conjugated polyene random copolymer produced by this process satisfies the following conditions:

1. The copolymer contains units derived (a) from ethylene and units derived (b) from an α-olefin having three or more carbon atoms, in a molar ratio of 40/60 to 95/5,

2. The iodine number is 1 to 50,

3. The intrinsic viscosity is more than 0.1 dl/g and less than 8.0 dl/g.

4. The intensity ratio D of Tαβ to Tαα in the ¹³CNMR spectrum is not more than 0.5,

5. The B value is 1.00 to 1.50,

6. The glass transition temperature Tg is not more than minus 56ºC, and

7. The ratio of the intrinsic viscosity of the copolymer to the intrinsic viscosity of a straight-chain ethylene-propylene copolymer having the same weight average molecular weight and an ethylene content of 70 mol% is greater than 0.9.

SUMMARY OF THE INVENTION

The invention has been made in consideration of the above situation in the prior art, and the object to be solved is first to improve the processing properties of an ethylene/α-olefin/non-conjugated diene copolymer rubber prepared by means of a metallocene catalyst in order to obtain an ethylene copolymer To provide a rubber composition that has an excellent balance of processing properties, mechanical properties and low temperature properties.

Second, the problem is to provide an ethylene copolymer rubber composition having excellent processing properties, low temperature properties, weather resistance and ozone resistance by blending a conjugated diene rubber with the above-mentioned ethylene copolymer rubber, which has excellent co-vulcanizability with the conjugated diene rubber and excellent processing properties without substantially impairing the mechanical properties and dynamic fatigue resistance inherent in the conjugated diene rubber.

The inventors conducted intensive studies to solve the above problems and consequently found that a composition containing a certain ethylene copolymer rubber has an excellent balance of properties.

According to the present invention, there is first provided an ethylene copolymer rubber composition (hereinafter referred to as the first invention) comprising an ethylene copolymer rubber and at least one member selected from the group consisting of a vulcanizing agent and a crosslinking agent, wherein the ethylene copolymer rubber is composed of ethylene; an α-olefin having 3 to 12 carbon atoms; a non-conjugated diene represented by the following structural formula (I):

wherein R¹ and R² independently represent hydrogen atoms or alkyl groups having 7 to 8 carbon atoms, R³ represents an alkyl group having 1 to 8 carbon atoms, and n is an integer of 2 to 10, and an α,ω-diene represented by the following structural formula (II):

CH&sub2; - CH - (CH2 )m - CH = CH2 (II)

where m is an integer from 1 to 10, and satisfies the following requirements (1) to (6):

(1) The molar ratio of ethylene to the α-olefin having 3 to 12 carbon atoms (ethylene/α-olefin) is in a range of 40/60 to 90/10;

(2) The iodine value is in the range of 5 to 45;

(3) The Mooney viscosity (ML₁₋₄, 100ºC) is in the range of 15 to 350;

(4) The ratio of the polystyrene-reduced weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) to the polystyrene-reduced number average molecular weight (Mn) determined by gel permeation chromatography (Mw/Mn) is in a range of 2.5 to 15;

(5) The glass transition temperature (Tg), determined by differential scanning calorimetry (DSC), is in the range of -55ºC to -80ºC;

(6) The branching index B, as defined here, is in the range of 0.60 to 0.95.

Secondly, the invention provides an ethylene copolymer rubber composition (hereinafter referred to as a second invention) comprising the above-mentioned ethylene copolymer rubber, a conjugated diene rubber, at least one member selected from the group consisting of a vulcanizing agent and a crosslinking agent, wherein the weight ratio of the above ethylene copolymer rubber to the above conjugated diene rubber (ethylene copolymer rubber/conjugated diene rubber) is in a range of 20/80 to 90/10.

DETAILED DESCRIPTION OF THE INVENTION

The components of the ethylene copolymer rubber compositions of the first and second inventions are explained in order below.

The ethylene copolymer rubber in the first and second inventions is a copolymer consisting of ethylene, an α-olefin having 3 to 12 carbon atoms (hereinafter referred to only as α-olefin), a non-conjugated diene represented by the above-mentioned structural formula (I), and an α,ω-diene represented by the above-mentioned structural formula (II).

The α-olefin includes, for example, the following compounds: propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 5-methyl-1-hexene, 1-octene, 5-ethyl-1-hexene, 1-nonene, 1-decene and 1-dodecene. Preferably, propylene, 1-butene, 1-hexene and 1-octene are used. These α-olefins may be used alone or as a mixture of two or more.

The molar ratio of ethylene to the α-olefin (ethylene/α-olefin) is in the range of 40/60 to 90/10, preferably 60/40 to 87/13. In the case where the above molar ratio is less than 40/60, sufficient mechanical strength cannot be obtained, and if it exceeds 90/10, damage to the rubber elasticity occurs.

The non-conjugated diene represented by the structural formula (I) includes in particular the following compounds: 5-methyl-1,5-heptadiene, 6-methyl-1,5-heptadiene, 6-methyl-1,6-octadiene, 7-methyl-1,6-octadiene, 7-methyl-1,7-nonadiene, 8-methyl-1,7-nonadiene, 8-methyl-1,8- decadiene, 9-methyl-1,8-decadiene, 9-methyl-1,9-undecadiene, 10-methyl-1,9-undecadiene, 10-methyl-1,10-dodecadiene, 11-methyl- 1,10-dodecadiene, 12-methyl-1,11-tridecadiene, 13-Methyl-1,11- tridecadiene, 12-methyl-1,12-tetradecadiene, 13-methyl-1,12-tetradecadiene, 13-methyl-1,13-pentadecadiene and 14-methyl-1,13-pentadecadiene. Preferably, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, 8-methyl-1,7-nonadiene and 9-methyl-1,8-decadiene are used. 7-methyl-1,6-octadiene is particularly preferably used. These non-conjugated dienes can be used alone or as a mixture of two or more.

The α,ω-diene represented by the structural formula (II) includes in particular 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene and 1,13-tetradecadiene. Preferably used are 1,5-hexadiene, 1,7-octadiene and 1,9-decadiene.

The amount of incorporation of the α,ω-diene represented by the structural formula (II) used in the first and second inventions is usually 0.5 to 30 mol%, preferably 1.5 to 15 mol%, based on the total amount of incorporation of the α,ω-diene and the non-conjugated diene represented by the structural formula (I). The iodine value of the ethylene copolymer rubber is in a range of 5 to 45, preferably 10 to 35. In the case where the iodine value is less than 5, the mechanical strength is inferior, and when the iodine value exceeds 45, the rubber elasticity is damaged.

The Mooney viscosity (M₁₋₄, 100°C) (hereinafter referred to only as Mooney viscosity) of the ethylene copolymer rubber is in a range of 15 to 350, preferably 20 to 300.

The ratio of the polystyrene-reduced weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) to the polystyrene-reduced number average molecular weight (Mn) determined by GPC is determined (Mw/Mn) is in a range from 2.5 to 15, preferably from 3 to 10.

The glass transition temperature (Tg) of the ethylene copolymer rubber, as determined by differential scanning calorimetry (DSC), is in a range of -55ºC to -80ºC, preferably from -56ºC to -75ºC.

In addition, the branching index B of the ethylene copolymer rubber is in a range of 0.60 to 0.95, preferably from 0.70 to 0.92. The value of this branching index B is determined by calculating the intrinsic viscosity [n₁] from Mw₁ obtained by GPC measurement of the target copolymer rubber using the viscosity equation [n0] = KMw₀ where K is a constant determined from the intrinsic viscosity [n0] of the model branch-free copolymer rubber and the polystyrene-reduced weight average molecular weight (Mw0) of the same copolymer rubber according to the viscosity GPC method (Michio Kurata, Journal of Japan Rubber Associate, (45) 1972), and then dividing the found value [n2] of the target copolymer rubber by the intrinsic viscosity [n1] calculated by the above viscosity equation. In this case, [n1] and [n2] represent values determined by measurement at 135°C in o-dichlorobenzene, and Mw1 is a value determined by measuring at 135ºC in o-dichlorobenzene using the GPC measurement method.

The ethylene copolymer rubber in the first and second inventions can be produced by a suitable method such as a gas phase polymerization method, a solution polymerization method and a slurry polymerization method. These polymerization operations can be carried out batchwise or continuously.

In the above-mentioned solution polymerization process or slurry polymerization process, inactive hydrocarbon is used as a reaction process.

As such an inactive hydrocarbon solvent, there may be mentioned aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane, n-decane, n-dodecane and the like; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene. These hydrocarbon solvents may be used alone or as a mixture of two or more. The starting monomers may also be used as the hydrocarbon solvent.

As the polymerization catalyst to be used in the production of the ethylene copolymer rubber in the first and second inventions, there can be mentioned, for example, an olefin polymerization catalyst consisting of an organometallic compound and a compound of a transition metal selected from the group consisting of V, Ti, Zr and Hf. Any of the above transition metal compounds and the above organometallic compounds may be used alone or as a mixture of two or more.

A particularly preferred example of the olefin polymerization catalyst is a metallocene catalyst consisting of a metallocene compound and an organoaluminum compound, or an ionic compound that can react with the metallocene compound and form an ionic complex.

A more detailed explanation of the polymerization catalyst for producing the ethylene copolymer rubber is given below, but in some cases, polymerization catalysts other than those mentioned below may be used.

As the above-mentioned metallocene catalyst, for example, a catalyst consisting of the following components (E) and (F), and mentions a catalyst consisting of the following components (G) and (H):

The component (E) is a transition metal compound represented by the following formula [1]:

R"s(C5Rm)p(R'nE)qMQ4-p-q [1]

wherein M is a metal of Group 4 of the Periodic Table of Elements; (C5Rm) is a cyclopentadienyl group or a substituted cyclopentadienyl group in which C5 represents a cyclopentadiene ring, the R groups are substituents on the cyclopentadiene ring and may be the same or different, each R includes a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms, and two R groups may be bonded to two adjacent carbon atoms of the cyclopentadiene ring to form a 4- to 8-membered carbon ring; E is an atom having a non-bonded electron pair; R' represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms; R" represents an alkylene group having 1 to 20 carbon atoms or a dialkylsilicon or a dialkylgermanium and is a group linking two ligands, s is 1 or 0; when s is 1, m is 4 and n is a digit which is two less than the valence of the E atom; when s is 0, m is 5 and n is a digit which is one less than the valence of the E atom; when n is ≥ 2, the R' groups may be the same or different and may be bonded to form a ring; Q represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms; and p and q are integers from 0 to 4 and satisfy the relationship 0 < p + q < 4.

Specific examples of the component (E) include the following compounds: bis(cyclopentadienyl)zirconium dichloride, bis(cyclopentadienyl)zirconium dibromide, bis(cyclopentadienyl)zirconium dimethyl, bis(cyclopentadienyl)zirconium diphenyl, dimethylsilylbis(cyclopentadienyl)zirconium dichloride, dimethylsilylbis(cyclopentadienyl)zirconium dimethyl, methylenebis(cyclopentadienyl)zirconium dichloride, ethylenebis(cyclopentadienyl)zirconium dichloride, bis(indenyl)zirconium dimethyl, dimethylsilylbis(indenyl)zirconium dichloride, methylenebis(indenyl)zirconium dichloride, bis(4,5,6,7-tetrahydroindenyl)zirconium dichloride, Bis(4,5,6,7-tetrahydroindenyl)zirconiumdimethyl, dimethylsilylbis(4,5,6,7-tetrahydroindenyl)zirconium dichloride, dimethylsilylbis(4,5,6,7-tetrahydroindenyl)zirconiumdimethyl, ethylenebis(4,5,6,7-tetrahydroindenyl)zirconiumdichloride, bis(methylcyclopentadienyl)zirconiumdi chloride, bis(methylcyclopentadienyl)- zirconium dimethyl, dimethylsilylbis(3-methyl-1-cyclopentadienyl) zirconium dichloride, methylenebis(3-methyl-1-cyclopentadienyl) zirconium dichloride, bis(tert-butylcyclopentadienyl)- zirconium dichloride, dimethylsilylbis(3-tert-butyl-1-cyclopentadienyl) zirconium dichloride, Bis(1,3-dimethylcyclopentadienyl)zirconium dichloride, dimethylsilylbis(2,4-dimethyl-1-cyclopentadienyl)zirconium dichloride, bis(1,2,4-trimethylcyclopentadienyl)zirconium dichloride, dimethylsilylbis(2,3,5-trimethyl-1-cyclopentadienyl)zirconium dichloride, bis(fluorenyl)zirconium dichloride, fluorenyl)zirconium dichloride, (fluorenyl)(cyclopentadienyl)zirconium dichloride, dimethylsilyl(fluorenyl)(cyclopentadienyl)zirconium dichloride, isopropylene(fluorenyl)(cyclopentadienyl)zirconium dichloride, (tert-butylamido)-(1,2,3,4,5-pentamethylcyclopentadienyl)-zirconium dichloride, Dimethylsilyl(tert-butylamido)(2,3,4,5-tetramethyl-1-cyclopentadienyl)zirconium dichloride, methylene-(tert-butylamido)(2,3,4,5-tetramethyl-1-cyclopentadienyl)-zirconium dichloride, (phenoxy)(1,2,3,4,5-pentamethylcyclopentadienyl)zirconium dichloride, dimethylsilyl(o-phenoxy )- (2,3,4,5-tetramethyl-1-cyclopentadienyl)zirconium dichloride, methylene(o-phenoxy)(2,3,4,5-tetramethyl-1-cyclopentadienyl)-zirconium dichloride, ethylene(o-phenoxy)(2,3,4,5-tetramethyl-1-cyclopentadienyl)zirconium dichloride, bis(dimethylamido)-zirconium dichloride, Bis(diethylamido)zirconium dichloride, bis(di-tert-butylamido)zirconium dichloride, dimethylsilylbis(methylamido)zirconium dichloride and dimethylsilylbis(tert-butylamido)zirconium dichloride and compounds obtained by replacing the zirconium of the above-mentioned compounds with titanium or hafnium. The above-mentioned transition metal compounds may be used alone or as a mixture of two or more.

The component (F) is an aluminoxane compound having units represented by the following general formula [2] and it is assumed that the aluminoxane compound is a linear, cyclic or cluster-like compound or a mixture of these compounds, although the chemical structure of the compound is not necessarily clearly defined:

-[A1 (Ra) -O]- [2]

wherein Ra represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms, preferably a methyl group, an ethyl group or an isobutyl group and particularly preferably a methyl group.

The above-mentioned aluminoxane compound can be prepared by a known method which comprises reacting an organoaluminum compound having at least one Ra group with water.

The ratio of the component (E) used to the component (F) used is usually in a range from 1/1 to 1/100,000, preferably from 1/5 to 1/50,000, expressed as the molar ratio of the transition metal to the aluminium atom (transition metal/aluminium atom).

The component (G) is a transition metal alkyl compound, which is represented by the following general formula [3] :

R"S(C5-Rm)p(R'nE)qMR'''4-p-q [3]

wherein M is a metal of Group 4 of the Periodic Table of Elements; (C5-Rm) is a cyclopentadienyl group or a substituted cyclopentadienyl group in which C5 represents a cyclopentadienyl ring, the R groups are substituents on the cyclopentadienyl ring and may be the same or different, each R represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 hydrocarbon atoms, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms, and two R groups may be bonded to two adjacent carbon atoms of the cyclopentadiene ring to form a 4- to 8-membered ring; E is an atom having a non-bonded electron pair; R' represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms; R" represents an alkylene group having 1 to 20 carbon atoms, a dialkylsilicon or a dialkylgermanium and is a group linking two ligands; s is 1 or 0; when s is 1, m is 4 and n is a digit which is two less than the valence of the E atom; when s is 0, m is 5 and n is a digit which is one less than the valence of the E atom; when n is ≥ 2, the R' groups may be the same or different and may be bonded to form a ring; R''' is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, an alkaryl group having 7 to 40 carbon atoms or an aralkyl group having 7 to 40 carbon atoms; p and q are integers from 0 to 3 and satisfy the relationship 0 < p + q ≤ 4.

Specific examples of the component (G) include the following compounds: bis(cyclopentadienyl)zirconiumdimethyl, bis(cyclopentadienyl)zirconiumdiethyl, bis(cyclopentadienyl)zirconiumdiisobutyl, bis(cyclopentadienyl)zirconiumdiphenyl, bis(cyclopentadienyl)zirconiumdi{bis(trimethylsilyl)methyl}, dimethylsilylbis(cyclopentadienyl)zirconiumdimethyl, dimethylsilylbis(cyclopentadienyl)zirconiumdiisobutyl, methylenebis(cyclopentadienyl)zirconiumdimethyl, ethylenebis(cyclopentadienyl)zirconiumdimethyl, bis-(indenyl)zirconiumdimethyl, bis(indenyl)zirconiumdiisobutyl, dimethylsilylbis(indenyl)zirconiumdimethyl, methylenebis-(indenyl)zirconiumdimethyl, Ethylenebis(indenyl)zirconiumdimethyl, Bis(4,5,6,7-tetrahydro-1-indenyl)zirconiumdimethyl, Dimethylsilylbis(4,5,6,7-tetrahydro-1-indenyl)zirconiumdimethyl, Ethylenebis(4,5,6,7-tetrahydroindenyl)zirconiumdimethyl, Bis(methylcyclopentadienyl)zirconiumdimethyl, 3-methyl-1-cyclopentadienyl)zirconiumdimethyl, bis(tert-butylcyclopentadienyl)zirconiumdimethyl, dimethylsilylbis(3-tert-butyl-1-cyclopentadienyl)zirconiumdimethyl, bis(1,3-dimethylcyclopentadienyl)zirconiumdiisobutyl, bis-(1,3-dimethylcyclopentadienyl)zirconiumdiisobutyl, Dimethylsilylbis(2,4-dimethyl-1-cyclopentadienyl)zirconiumdimethyl, methylenebis(2,4-dimethyl-1-cyclopentadienyl)zirconiumdimethyl, ethylenebis(2,4-dimethyl-1-cyclopentadienyl)zirconiumdimethyl, bis(1,2,4-trimethylcyclopentadienyl)zirconiumdimethyl, dimethylsilylbis(2,3,5-trimethyl-1-cyclo pentadienyl)-zirconiumdimethyl, bis(fluorenyl)zirconiumdimethyl, dimethylsilylbis(fluorenyl)zirconiumdimethyl, (fluorenyl)(cyclopentadienyl)zirconiumdimethyl, dimethylsilyl(fluorenyl)(cyclopentadienyl)zirconiumdimethyl, isopropylene(fluorenyl)(cyclopentadienyl)zirconiumdimethyl, (tert-Butylamido)(1,2,3,4,5-pentamethylcyclopentadienyl)zirconiumdimethyl, Dimethylsilyl- (tert-butylamido)(2,3,4,5-tetramethyl-1-cyclopentadienyl)-zirconiumdimethyl, Methylene(tert-butylamido)(2,3,4,5-tetramethyl-1-cyclopentadienyl)zirconiumdimethyl, (Phenoxy)- 1,2,3,4,5-pentamethylcyclopentadienyl)zirconiumdimethyl, dimethylsilyl(o-phenoxy)(2,3,4,5-tetramethyl-1-cyclopentadienyl)zirconiumdimethyl, Methylene(o-phenoxy)(2,3,4,5-tetramethyl-1-cyclopentadienyl)zirconium dimethyl, bis(dimethylamido)zirconium dimethyl, bis(diethylamido)zirconium dimethyl, bis(di-tert-butylamido)zirconium dimethyl, dimethylsilylbis(methylamido)zirconium dimethyl, dimethylsilylbis(tert-butylamido)zirconium dimethyl and the like, and compounds in which the zirconium of these zirconium compounds has been replaced by titanium or hafnium. The above transition metal alkyl compounds may be used alone or as a mixture of two or more.

The transition metal alkyl compound may be synthesized beforehand, or it may be prepared by bringing a transition metal halide represented by the formula [3] in which R" is a halogen atom into contact with an organometallic compound such as trimethylaluminum, triethylaluminum, diethylaluminum monochloride, triisobutylaluminum, methyllithium or butyllithium in the reaction system.

The component (H) is an ionic compound represented by the following general formula [4]:

([L]k+) p ([M'A1 A2...An]-)q [4]

wherein [L]k+ is a Bronsted acid or a Lewis acid; M' is an element of group 13 to 15 of the Periodic Table of the Elements; A1 to An are independently hydrogen atoms, halogen atoms, alkyl groups having 1 to 20 carbon atoms, dialkylamino groups having 1 to 30 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, aryl groups having 6 to 40 carbon atoms, aryloxy groups having 6 to 40 carbon atoms, alkaryl groups having 7 to 40 carbon atoms, aralkyl groups having 7 to 40 carbon atoms, halogen-substituted hydrocarbon groups having 1 to 40 carbon atoms, acyloxy groups having 1 to 20 carbon atoms or organometalloid groups; k is the ionic valence of L is an integer from 1 to 3; p is an integer of 1 or more and q = (k · p).

Specific examples of the component (H) include the following compounds: trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, tri-n-butylammonium tetraphenylborate, methyl(di-n-butyl)ammonium tetraphenylborate, dimethylanilinium tetraphenylborate, methylpyridinium tetraphenylborate, methyl(2-cyanopyridinium)tetraphenylborate, methyl(4-cyanopyridinium)tetraphenylborate, trimethylammonium tetrakis(pentafluorophenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, tri-n-butylammonium tetrakis(pentafluorophenyl)borate, methyl(di-n-butyl)ammonium tetrakis(pentafluorophenyl)borate, Dimethylanilinium tetrakis(pentafluorophenyl)borate, methylpyridinium tetrakis(pentafluorophenyl)borate, methyl(2- cyanopyridinium)tetrakis(pentafluorophenyl)borate, methyl(4- cyanopyridinium)tetrakis(pentafluorophenyl)borate, dimethylanilinium tetrakis[3,5,di-(trifluoromethyl)phenyl]borate, ferrocenium tetraphenylborate, silver tetraphenylborate and ferrocenium tetrakis(pentafluorophenyl)borate. The above-mentioned ionic compounds may be used alone or as a mixture of two or more.

The proportions of the components (G) and (H) are usually used in a range from 1/0.5 to 1/20, preferably from 1/0.8 to 1/10, based on the (G)/(H) molar ratio.

The above-mentioned metallocene catalyst used in the production of the ethylene copolymer rubber of the first and second inventions may be used in the form that at least a part of it is supported on a suitable carrier. The kind of the carrier is not critical, and any of an inorganic oxide carrier, any other organic carrier, and any organic carrier may be used. The method of supporting on the carrier is not critical, and a known method may be suitably used.

The conjugated diene rubber in the second invention includes, for example, natural rubber, styrene-butadiene rubber, polybutadiene rubber, acrylonitrile-butadiene rubber and polyisoprene rubber, and also hydrogenated products of these rubbers. Preferably, natural rubber, styrene-butadiene rubber, polybutadiene rubber and polyisoprene rubber are used. The hydrogenation degree of the above hydrogenated products of the rubber is usually 20 to 99%, preferably 50 to 95%. These conjugated diene rubbers may be used alone or as a mixture of two or more.

The Mooney viscosity of the conjugated diene rubber is preferably 10 to 100, more preferably 20 to 80.

The weight ratio of the ethylene copolymer rubber to the conjugated diene rubber (ethylene copolymer rubber/conjugated diene rubber) in the ethylene copolymer composition of the second invention is in a range of from 20/80 to 90/10, preferably from 30/70 to 70/30, and most preferably from 50/50 to 70/30. In the case where the above weight ratio is less than 20/80, the ozone resistance of the vulcanized rubber is inferior, and if the weight ratio exceeds 9/10, the mechanical strength of the vulcanized rubber is insufficient in some cases and thus such weight ratios are not desirable.

Among the vulcanizing and crosslinking agents used in the first and second inventions, the vulcanizing agent includes, for example, sulfur such as powdery sulfur, precipitated sulfur, colloidal sulfur and insoluble sulfur; inorganic vulcanizing agents such as sulfur chloride, selenium and tellurium; sulfur-containing organic compounds such as morpholine disulfides, alkylphenol disulfides, thiuram disulfides and dithiocarbamic acid salts. These vulcanizing agents may be used alone or as a mixture of two or more.

The amount of the vulcanizing agent blended is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the ethylene copolymer rubber in the first invention, and usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the total of the ethylene copolymer rubber and the conjugated diene rubber in the second invention.

A vulcanization accelerator may be used together with the above vulcanizing agent.

Such a vulcanization accelerator includes, for example, the following compounds: aldehyde-ammonia adducts, such as hexamethylenetetramine; guanidines, such as diphenylguanidine, di(o-tolyl)guanidine and o-tolylbiguanide; thioureas, such as thiocarbonilide, di(o-tolyl)thiourea, N,N'-diethylthiourea, tetramethylthiourea, trimethylthiourea and dilaurylthiourea; thiazoles, such as mercaptobenzothiazole, dibenzothiazole disulfide, 2-(4-morpholinothio)benzothiazole, 2-(2,4-dinitrophenyl)mercaptobenzothiazole and (N,N'-diethylthiocarbamoylthio)benzothiazoles; Sulfenamides, such as N-tert-butyl-2-benzothiazylsulfenamide, N,N'-dicyclohexyl-2-benzothiazylsulfenamide, N,N'-diisopropyl-2-benzothiazylsulfenamide and N-cyclohexyl-2-benzothiazylsulfenamide; Thiurams, such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetra-n-butylthiuram disulfide, tetramethylthiuram monosulfide and dipentamethylenethiuram tetrasulfide; Carbamic acid salts such as zinc dimethylthiocarbamate, zinc diethylthiacarbamate, zinc di-n-butylthiocarbamate, zinc ethylphenyldithiocarbamate, sodium dimethyldithiocarbamate, copper dimethyldithiocarbamate, tellurium dimethylthiocarbamate, iron dimethylthiocarbamate and the like; xanthogenic acid salts such as zinc butylthioxanthate. These vulcanization accelerators can be used alone or as a mixture of two or more.

The amount of the vulcanization accelerator added in the first invention is usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, per 100 parts by weight of the ethylene copolymer rubber, and in the second invention usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, per 100 parts by weight of the total of the ethylene copolymer rubber and the conjugated diene rubber.

In addition to the above-mentioned vulcanizing agent and the above-mentioned vulcanization accelerator, a vulcanization accelerator coagent may be added if necessary.

Such a vulcanization accelerating coagent includes, for example, metal oxides such as magnesium oxide, zinc white, lead monoxide, red lead and white lead; organic acids and their salts such as stearic acid, oleic acid and zinc stearate; with zinc white and stearic acid being particularly preferred. These vulcanization accelerating coagents may be used alone or as a mixture of two or more.

The amount of the vulcanization accelerating coagent blended is usually 0.5 to 20 parts by weight per 100 parts by weight of the ethylene copolymer rubber in the first invention, and usually 0.5 to 20 parts by weight per 100 parts by weight of the total of the ethylene copolymer rubber and the conjugated diene rubber in the second invention.

The crosslinking agent includes, for example, organic peroxides such as 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, di-tert-butyl peroxide, dicumyl peroxide, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and 1,3-bis(tert-butylperoxyisopropyl)benzene. These crosslinking agents may be used alone or as a mixture of two or more.

The amount of the crosslinking agent blended is usually 0.1 to 15 parts by weight, preferably 0.5 to 10 parts by weight, per 100 parts by weight of the ethylene copolymer rubber in the first invention and usually 0.1 to 15 parts by weight, preferably 0.5 to 10 parts by weight per 100 parts by weight of the total of the ethylene copolymer rubber and the conjugated diene rubber.

Furthermore, a crosslinking agent coagent may be used together with the above-mentioned crosslinking agent.

Such a crosslinking agent coagent includes, for example, sulfur and sulfur compounds such as dipentamethylenethiuram tetrasulfide; polyfunctional monomers such as ethylene di(meth)acrylate, polyethylene di(meth)acrylate, divinylbenzene, diallyl phthalate, triallyl cyanurate, metaphenylenebismaleimide and toluenebismaleimide; and oxime compounds such as p-quinone oxime and pp'-benzoylquinone oxime. These crosslinking agent coagents may be used alone or as a mixture of two or more.

The amount of the crosslinking agent blended is usually 0.5 to 20 parts by weight per 100 parts by weight of the ethylene copolymer rubber in the first invention, and usually 0.5 to 20 parts by weight per 100 parts by weight of the total of the ethylene copolymer rubber and the conjugated diene rubber in the second invention.

Furthermore, the ethylene copolymer rubber composition in the first and second inventions may be mixed with a filler or a plasticizer.

The above filler includes, for example, carbon black such as SRF, FEF, HAF, ISAF, SAF, FT, MT and the like; inorganic fillers such as white carbon black, finely divided magnesium silicate, calcium carbonate, magnesium carbonate, clay and talc. These fillers may be used alone or as a mixture of two or more.

The amount of the filler blended is usually 10 to 200 parts by weight, preferably 10 to 100 parts by weight, per 100 parts by weight of the ethylene copolymer rubber in the first invention and usually 10 to 200 parts by weight, preferably 10 to 100 parts by weight, per 100 parts by weight of the total of the ethylene copolymer rubber and the conjugated diene rubber.

The plasticizer includes, for example, plasticizer oils such as aromatic oils, naphthenic oils and paraffin oils commonly used in rubbers; vegetable oils and the like such as coconut oil and the like; synthetic oils such as alkylbenzene oils. Among them, plasticizer oils are preferred and paraffin oil is particularly preferred. The above plasticizers may be used alone or as a mixture of two or more.

The amount of the softening agent blended is usually 10 to 130 parts by weight, preferably 20 to 100 parts by weight, per 100 parts by weight of the ethylene copolymer rubber in the first invention, and usually 10 to 130 parts by weight, preferably 20 to 100 parts by weight, per 100 parts by weight of the total of the ethylene copolymer rubber and the conjugated diene rubber in the second invention.

Furthermore, the ethylene copolymer rubber composition of the first and second inventions can be used in admixture with at least one other rubber or at least one other resin selected from the group consisting of other ethylene/α-olefin/non-conjugated diene copolymers, ethylene/α-olefin copolymers, polyethylene and polypropylene.

In producing the ethylene copolymer rubber compositions of the first and second inventions, conventional kneaders, extruders and vulcanizers can be used.

The method and order of mixing the vulcanizing agent and/or crosslinking agent, filler, plasticizer and the like with the ethylene copolymer rubber alone or together with the conjugated Diene rubber consists of the following steps: Using a Banbury mixer, the ethylene copolymer rubber alone or together with the conjugated diene rubber is mixed with the filler and the plasticizer, and then the resulting mixture is mixed with the vulcanizing agent and/or the crosslinking agent using a roller.

Subsequently, a vulcanized rubber can be produced from the ethylene copolymer rubber composition by a conventional method of producing vulcanized rubber, for example, by placing the ethylene copolymer rubber in a mold and raising the temperature in the mold to vulcanize the composition, or by molding the composition into a desired shape by means of an extruder and then heating the molded composition in a vulcanization vessel to vulcanize the composition.

The ethylene copolymer rubber composition of the first invention can be suitably used for various wires, electrical insulating parts, roof coverings, pipes, belts, building materials, rubber rollers, rubber insulators for preventing transmission of shock, sponge products, and also as applications for automobile parts such as door and window rubbers, cooling water hoses, heater hoses, brake hoses, voltage protectors, muffler hangers, brake shoes, lamp sockets, and bumpers.

The ethylene copolymer rubber composition of the second invention can be suitably used in tires, rubber insulators against vibration transmission, window frames, various door and window rubbers and materials for construction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Examples are given below to explain the invention in more detail.

In the examples and comparative examples, the measurements and evaluations were carried out using the following methods:

(a) α-Olefin content

It was determined by the 13C-NMR method under the condition that the ethylene content (mol%) and the α-olefin content (mol%) in each example and each comparative example were based on the total (100 mol%) of the ethylene content and the α-olefin content.

(b) Iodine number

It was determined using the infrared absorption spectrum method.

(c) Mooney viscosity

It was determined in accordance with JIS K6300 under conditions where the measurement temperature was 100ºC, the preheating time was 1 minute and the time until the viscosity was read was 4 minutes.

(d) Mw/Mn

Determined by GPC at 135ºC in o-chlorobenzene.

(e) Glass transition temperature Tg

Using a differential scanning calorimeter Model 910 manufactured by DU PONT INSTRUMENT, a sample was heated to 180ºC and then cooled to -90ºC at a rate of 10ºC/min, and then a measurement was made by raising the temperature at a rate of 20ºC/min.

(f) Branching index B

It was measured using the GPC apparatus Model 150CV GPC manufactured by Waters Company in o-dichlorobenzene at a sample concentration of 0.15 wt% at 135ºC.

(g) Roll processability

The roller processability was assessed using the following five criteria:

5: The rubber sheet was fully bonded to the roller, and the bead of material rotated smoothly.

4: The rubber skin was located between the top of the roller and the material bead, slightly separated from the surface of the roller.

3: The rubber skin was clearly separated from the surface of the roller between the top of the roller and the material bead.

2: The rubber skin did not adhere well to the surface of the roller, but hung down from it, and roller processing was impossible without holding the rubber skin by hand.

1: The rubber tape did not stick to the surface of the roller at all, but hung down from it, and roller processing without holding the rubber tape by hand was impossible.

(h) Tackiness during roller processing The tackiness to the roller was evaluated using the following four criteria: excellent ( ), good (0), fair (Δ) and poor (x).

(i) Appearance of the mixture taken from the plastomill The take-away of a rubber mixture during kneading in a plastomill was assessed based on the following 4 criteria:

: The retrievability was excellent, ○: the retrievability was good, Δ: the coherence of the retrieved rubber was slightly poor, x: the retrieved rubber showed no coherence.

(j) Tensile test

The tensile strength TB (MPa) and elongation at break EB (%) were measured according to JIS K6301 using a No. 3 test specimen at a measuring temperature of 25ºC and a pulling speed of 500 mm/min.

(k) Endurance test

The spring hardness (JIS-A hardness) was measured according to JIS K6301.

(l) Compression deformation test

It was carried out according to JIS K6301 under conditions of 70ºC for 22 hours.

(m) Low temperature torsion test (Gehman temperature)

T5 (ºC) was measured according to JIS K6301.

(n) Testing of vulcanization properties

Using a Curastometer Model V manufactured by Japan Synthetic Rubber Co., Ltd., the torque maximum MH was determined from the vulcanization curve at a temperature of 160ºC for 30 minutes.

(o) Tensile fatigue test (crack propagation)

A No. 1 dumbbell specimen was prepared as specified in JIS K6301 and a crack was previously generated at the center in the longitudinal direction, and the resulting 10 crack specimens were subjected to a elongation fatigue test under the conditions of 75% elongation, 30ºC measurement temperature and 300 rpm rotation speed, and the average of the cycles required until the test specimen broke was determined.

(Crack generation)

The same test specimens as above except that no crack was previously generated therein were subjected to the same test as in the above crack propagation test except that the elongation was 100%, and the average of the cycles required until the test specimen broke was determined.

(p) Ozone resistance test

The crack generation time was measured according to JIS-K6301 under the conditions of ozone concentration of 50 phm and elongation of 50% and used as an index of ozone resistance. The test duration was 14 days,

example 1 (Manufacture of ethylene copolymer rubber)

In a 3-liter stainless steel autoclave sufficiently purged with nitrogen, 1.45 liters of purified toluene, 450 milliliters of 1-octene, 45 milliliters of 7-methyl-1,6-octadiene and 1.7 milliliters (8.9 millimoles) of 1,9-decadiene were charged and the temperature was raised to 30ºC, after which the internal pressure of the autoclave was adjusted to 5 kg/cm2 while ethylene was continuously supplied at a rate of 14 normal liters/minute.

Separately, into a 50 milliliter glass flask sufficiently purged with nitrogen and into which a magnetic stirrer was installed, 3.0 μmol of isopropylene(fluorenyl)(cyclopentadienyl)zirconium dichloride dissolved in 3.0 milliliters of purified toluene and 1.5 millimoles of triisobutylaluminum dissolved in 6.0 milliliters of purified toluene were charged and stirred at room temperature for 30 minutes to subject them to reaction. Then, 3.6 μmol of dimethylanilinium tetrakis(pentafluorophenyl)borate dissolved in 7.2 milliliters of purified toluene was added to the reaction mixture and it was stirred at room temperature for 20 minutes to subject it to reaction, thereby obtaining a polymerization catalyst.

This polymerization catalyst was fed into the above autoclave to start polymerization. During the reaction, the temperature was kept at 30°C, the internal pressure of the autoclave was kept at 5 kg/cm2, ethylene was continuously fed and polymerization was carried out under these conditions for 15 minutes. Then, a small amount of methanol was added to terminate the reaction, after which the solvent was removed by steam distillation and the product was dried on a 6-inch (15.2 cm) roll to obtain 155 g of a polymer.

This polymer was an ethylene/1-octene/7-methyl-1,6-octadiene/1,9-decadiene copolymer rubber having an ethylene content of 71.5 mol%, a 1-octene content of 28.5 mol%, an iodine value of 15.5, a Mooney viscosity of 45, an Mw/Mn ratio of 5.5, a Tg of -68.7°C and a branching index B of 0.835. This ethylene copolymer rubber is hereinafter referred to as copolymer rubber (R1).

(Preparation and evaluation of rubber composition) The copolymer rubber (R1) was kneaded with the ingredients shown in Table 3, excluding the vulcanizing agent, using a Laboplastomill (internal volume: 250 milliliters) at 60 rpm for 150 seconds at 60°C to obtain the mixture (i). Then, to the mixture (i) were added the vulcanizing agent ingredients shown in Table 3 and they were kneaded for 5 minutes on a 10-inch roll (25.4 cm roll) kept at 50°C to obtain the mixture (ii).

Then, this mixture (ii) was heated by means of a hot press heated to 160°C under such a pressure that the press pressure became 150 kgf/cm2 for 30 minutes to prepare a vulcanized sheet having a size of 120 x 120 x 2 mm and a sample for compression set test, and they were subjected to evaluation of various properties.

As a result, the composition using the copolymer rubber (R1) had low hardness and excellent balance of processing properties and mechanical and low temperature properties. The evaluation results are shown in Table 4.

Example 2 (Manufacture of ethylene copolymer rubber)

Into a 3-liter stainless steel autoclave which had been sufficiently purified with nitrogen, 1.9 liters of purified toluene, 45 milliliters of 7-methyl-1,6-octadiene, 1.7 milliliters (8.9 millimoles) of 1,9-decadiene and 18 millimoles, in terms of aluminum atoms, of methylaluminoxane dissolved in 15 milliliters of purified toluene were charged, and the temperature was raised to 30°C, after which the internal pressure of the autoclave was adjusted to 4 kg/cm2, with ethylene and propylene each continuously supplied at a rate of 12 normal liters/minute. Then, 3.6 µmol of ethylenebis(indenyl)zirconium dichloride dissolved in 4.5 milliliters of toluene was added to the autoclave to initiate polymerization. During the reaction, the temperature was kept at 30°C, the internal pressure of the autoclave was kept at 4 kg/cm2, ethylene was continuously supplied, and polymerization was carried out under these conditions for 15 minutes. Then, a small amount of methanol was added to the autoclave to terminate the reaction, after which the solvent was removed by steam distillation and the product was dried on a 6-inch roller to obtain 161 g of a polymer.

This polymer was an ethylene/propylene/7-methyl-1,6-octadiene/1,9-decadiene copolymer rubber having an ethylene content of 75 mol%, a propylene content of 25 mol%, an iodine number of 13, a Mooney viscosity of 95, an Mw/Mn ratio of 4.8, a Tg of -58.7°C and a branching index B of 0.892. This ethylene copolymer rubber is hereinafter referred to as copolymer rubber (R2).

(Preparation and evaluation of rubber composition) In the same manner as in Example 1 except that the copolymer rubber (R1) was replaced by the copolymer rubber (R2), the compounds (i) and the compounds (ii) and various physical properties were evaluated.

As a result, the composition using the copolymer rubber (R2) exhibited an excellent balance of processing properties and mechanical and low-temperature properties. The evaluation results are shown in Table 4.

Examples 3 to 8

In the same manner as in Example 1 or Example 2, the copolymer rubbers (R3) to (R8) shown in Table 1 were prepared; and the blends (i) and the blends (ii) were prepared; and various physical properties were evaluated.

As a result, the compositions using these copolymer rubbers exhibited an excellent balance of processing properties and mechanical and low temperature properties. The evaluation results are shown in Table 4.

Comparative examples 1 to 4

In the same manner as in Example 1 or Example 2, copolymer rubbers (r1) to (r4) shown in Table 2 were prepared; and blends (i) and (ii) were prepared; and various physical properties were evaluated.

As a result, the compositions using these copolymer rubbers were insufficient in the balance of processing properties and mechanical and low temperature properties. The results of the evaluation are shown in Table 5. Table 1

Note: (*1) Mol-% based on the total amount of non-conjugated diene and α,ω-diene

(*2) 7-methyl-1,6-octadiene (*3) 1,9-decadiene

(*4) 6-methyl-1,5-heptadiene (*5) 1,7-octadiene Table 2

Note: (*2) 7-methyl-1,6-octadiene

(*6) 5-Ethylidene-2-norbornene

Table 3 Formulation parts by weight

Copolymer rubber 100

Soot (*7) 75

Plasticizer oil (*8) 35

Zinc white 5

Stearic acid 1

Vulcanizing agent components

- Sulphur 1.5

- Vulcanization accelerator M (*9) 0.5

- Vulcanization accelerator TT (*10) 1.0

Notes: (*7) Manufactured by Tokai Carbon Co., Ltd. (trade name: Seast G116)

(*8) Manufactured by Idemitsu Kosan Co., Ltd. (trade name: Diana Process Oil PW-380)

(*9) Mercaptobenzothiazol

(*10) Tetramethylthiuram disulfide Table 4 Table 5

Examples 9 and 10

Copolymer rubber (R2) or (R3), natural rubber and the other ingredients shown in Table 6 except the vulcanizing agent ingredients were kneaded at 60 rpm for 150 seconds at 60°C using a Laboplastomill (internal volume: 250 milliliters) to obtain the compound (i). Then, the vulcanizing agent ingredients shown in Table 6 were added to the compound (i) and they were kneaded on a 10 inch (25.4 cm roll) kept at 50°C for 5 minutes to obtain the compound (ii).

Then, the compound (ii) was heated for 30 minutes by means of a hot roll heated to 160°C under such a pressure that the press pressure became 150 kgf/cm² to prepare a vulcanized sheet having a size of 120 x 120 x 2 mm and a sample for compression set test, which was then subjected to evaluation of various properties.

As a result, the compositions using these copolymer rubbers had excellent co-vulcanizability and also excellent balance of processing properties and mechanical properties and resistance to dynamic fatigue. The evaluation results are shown in Table 7.

Comparative examples 5 to 7

In the same manner as in Example 9 or 10 except that the copolymer rubber (R2) or (R3) was replaced by the copolymer rubber (r1), (r3) or (r4), the compounds (i) and (ii) were prepared and evaluated for various physical properties.

As a result, the compositions using these copolymer rubbers had inferior copolymerizability and were insufficient in the balance of processing properties and mechanical properties and resistance to dynamic fatigue. The results of the evaluation are shown in Table 7.

Table 6 Formulation parts by weight

Copolymer rubber 50

Natural rubber (*11) 50

Soot (*12) 60

Plasticizer oil (* 8) 40

Zinc white 5

Stearic acid 1

Vulcanizing agent components

- Sulphur 1.5

- Vulcanization accelerator MSA (*13) 0.5

- Vulcanization accelerator D (*14) 1.0

Notes: (*8) Manufactured by Idemitsu Kosan Co., Ltd. (trade name: Diana Process Oil PW-380)

(*11) Manufactured by (Trade name: RSS#1)

(*12) Manufactured by Tokai Carbon Co., Ltd. (trade name: Seast SO)

(*13) N-oxydiethylene-2-benzothiazolesulfenamide

(*14) Diphenylguanidine Table 7

The ethylene copolymer rubber composition of the first invention has excellent processing properties and also an excellent balance of processing properties and mechanical and low-temperature properties. The ethylene copolymer rubber composition of the second invention has excellent co-vulcanizability and also an excellent balance of processing properties and mechanical properties and resistance to dynamic fatigue and further excellent low-temperature properties, weather resistance and ozone resistance. Accordingly, these ethylene copolymer rubber compositions can be widely used in a very suitable manner.

Examples 11 and 12

Copolymer rubber (R2) or (R3), natural rubber and the other ingredients shown in Table 8 except the vulcanizing agent ingredient were kneaded at 60 rpm for 150 seconds at 60°C using a Laboplastomill (internal volume: 250 milliliters) to obtain the compound (i). Then, the vulcanizing agent ingredients were added to the mixture (i) and they were kneaded on a 10 inch roll (25.4 cm roll) maintained at 50°C for 5 minutes to obtain the mixture (ii).

Then, the compound (ii) was heated for 30 minutes by means of a hot roll heated to 160°C under such a pressure that the press pressure became 150 kgf/cm² to prepare a vulcanized sheet having a size of 120 x 120 x 2 mm and a sample for compression set test, which was then subjected to evaluation of various properties.

The formulation is shown in Table 8 and the results of the evaluations are shown in Table 7.

Comparative examples 8 to 10

In the same manner as in Example 11 or 12 except that the copolymer rubber (R2) or (R3) was replaced by the copolymer rubber (r1), (r3) or (r4), the compounds (i) and (ii) were prepared and the evaluation of various physical properties was made.

As a result, the compositions using these copolymer rubbers had inferior co-vulcanizability and showed insufficient balance of processing properties and mechanical properties and resistance to dynamic fatigue. The evaluation results are shown in Table 9.

Table 8 Formulation parts by weight

Natural rubber (*11) 70

Ethylene polymer 30

Soot (*12) 60

Plasticizer oil (* 8) 40

Zinc white 5

Stearic acid 1

Vulcanizing agent components

- Sulphur 1.5

- Vulcanization accelerator MSA (*13) 0.5

- Vulcanization accelerator D (*14) 1.0

Notes: (*8) Manufactured by Idemitsu Kosan Co., Ltd. (trade name: Diana Process Oil PW-380)

(11) Manufactured by (Trade name: RSS#1)

(*12) Manufactured by Tokai Carbon Co., Ltd. (trade name: Seast SO)

(*13) N-oxydiethylene-2-benzothiazolesulfenamide

(*14) Diphenylguanidine Table 9

Claims (9)

1. An ethylene copolymer rubber composition comprising an ethylene copolymer rubber and at least one member selected from the group consisting of a vulcanizing agent and a crosslinking agent, wherein the ethylene copolymer rubber is composed of ethylene, an α-olefin having 3 to 12 carbon atoms, a non-conjugated diene represented by the following structural formula (I): wherein R¹ and R² independently represent hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, R³ represents an alkyl group having 1 to 8 carbon atoms, and n is an integer of 2 to 10, and an α,ω-diene represented by the following structural formula (II): CH2 =CH-(CH2 )m-CH=CH2 (II) where m is an integer from 1 to 10, and satisfies the following requirements (I) to (6): (1) The molar ratio of ethylene and the α-olefin having 3 to 12 carbon atoms (ethylene/α-olefin) is in a range of 40/60 to 90/10; (2) The iodine value is in the range of 5 to 45; (3) The Mooney viscosity (Mh₁₋₄, 100ºC) is in the range of 15 to 350; (4) The ratio of the polystyrene-reduced weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) to the polystyrene-reduced number average molecular weight (Mn) determined by GPC (Mw/Mn) is in a range of 2.5 to 15; (5) The glass transition temperature (Tg), determined by differential scanning calorimetry (DSC), is in the range of -55ºC to -80ºC; (6) The branching index B, as defined here, is in the range of 0.60 to 0.95. 2. An ethylene copolymer rubber composition comprising the ethylene copolymer rubber according to claim 1, a conjugated diene rubber and at least one member selected from the group consisting of a vulcanizing agent and a crosslinking agent, wherein the weight ratio of the ethylene copolymer rubber to the conjugated diene rubber (ethylene copolymer rubber/conjugated diene rubber) is in a range of 20/80 to 90/10. 3. The ethylene copolymer rubber composition of claim 1 or claim 2, wherein the ethylene copolymer rubber is composed of ethylene; at least one α-olefin selected from the group consisting of propylene, 1-butene, 1-hexene and 1-octene; at least one non-conjugated diene selected from the group consisting of 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, 8-methyl-1,7-nonadiene and 9-methyl- 1,8-decadiene; and at least one α,ω-diene selected from the group consisting of 1,5-hexadiene, 1,7-octadiene and 1,9-decadiene. 4. An ethylene copolymer rubber composition according to claim 1 or claim 2, wherein the molar ratio of ethylene to the α-olefin is in a range of 60/40 to 87/13. 5. An ethylene copolymer rubber composition according to claim 4, wherein the ethylene copolymer rubber has an iodine value in a range of 10 to 35; a Mooney viscosity in a range of 20 to 300; an Mw/Mn ratio in a range of 3 to 10; a glass transition temperature as determined by DSC in a range of -56°C to -75ºC and a branching index B, as defined herein, in a range of 0.70 to 0.92. 6. The ethylene copolymer rubber composition according to claim 2, wherein the conjugated diene is at least one member selected from the group consisting of natural rubber, styrene-butadiene rubber, polybutadiene rubber, polyisoprene rubber and hydrogenation products thereof. 7. The ethylene copolymer rubber composition according to claim 6, wherein the conjugated diene rubber has a Mooney viscosity of 10 to 100. 8. The ethylene copolymer rubber composition according to claim 2, wherein the weight ratio of the ethylene copolymer rubber to the conjugated diene rubber is in a range from 30/70 to 70/30. 9. An ethylene copolymer rubber composition according to claim 1 or claim 2, wherein the vulcanizing agent is sulfur selected from the group consisting of powdery sulfur, precipitated sulfur, colloidal sulfur and insoluble sulfur; an inorganic vulcanizing agent selected from the group consisting of sulfur chloride, selenium and tellurium; or a sulfur-containing organic compound selected from the group consisting of morpholine, alkylphenol disulfides, thiuram disulfides and dithiocarbamic acid salts and is contained in a proportion of 0.1 to 10 parts by weight per 180 parts by weight of the ethylene copolymer rubber; and wherein the crosslinking agent is an organic peroxide selected from the group consisting of 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, di-tert-butyl peroxide, dicumyl peroxide, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and 1,3-bis(tert-butylperoxyisopropyl)benzene, and is contained in a proportion of 0.1 to 15 parts by weight per 100 parts by weight of the ethylene copolymer rubber.