JPH11100462A - Rubber composition for tire side wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ethylenic copolymerized rubber composition, excellent in covulcanization of the ethylenic copolymer rubber and a conjugated dienic rubber, while maintaining mechanical characteristics and dynamic fatigue characteristics, which are substantial characteristics original to the conjugated dienic rubber vulcanizate and usable for production of a tire side wall excellent in weather resistance and ozone resistance. SOLUTION: This ethylenic copolymerized rubber composition for a tire side wall comprises (A) a brominated ethylenic copolymerized rubber obtained by brominating a copolymerized rubber composed of ethylene, α-olefin, and a nonconjugated polyene, and having 0.2-5 wt.% bromine content and (B) a conjugated dienic rubber in a weight ratio (the brominated ethylenic copolymerized rubber A/ the dienic rubber B) of 50/50-10/90.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ethylene copolymer rubber composition used for the production of tire sidewalls, and more particularly, to an excellent copolymer vulcanizability with a conjugated diene rubber.
The present invention relates to an ethylene copolymer rubber composition for producing a tire sidewall excellent in weather resistance and ozone resistance while substantially maintaining the original mechanical properties and dynamic fatigue resistance properties of a conjugated diene rubber vulcanizate. .

[0002]

2. Description of the Related Art Conventionally, rubbers for tire sidewalls include natural rubber (NR) and polybutadiene rubber (B).
R). However, N
Since both R and BR have many unsaturated bonds in the main chain, there has been a problem that heat aging resistance, weather resistance and ozone resistance are inferior.

On the other hand, blends of ethylene / α-olefin / non-conjugated diene copolymer (EPDM) and styrene / butadiene rubber (SBR) which are excellent in weather resistance, heat resistance, ozone resistance and the like are being studied. .

However, the ethylene / α-olefin / non-conjugated diene copolymer is inferior in co-vulcanizability with a conjugated diene rubber, so that the weather resistance, ozone resistance and dynamic fatigue resistance required for the tire sidewall are required. A satisfactory vulcanizate in terms of properties and strength has not been obtained.

JP-A-59-176338 discloses a halogenated ethylene.α containing 1 to 40% by weight of halogen.
-An anti-vibration rubber composition containing an olefin / non-conjugated diene copolymer rubber in an amount of 30% by weight or more based on the total amount of rubber components has been proposed. This rubber composition gives a vulcanizate having excellent vibration absorption characteristics and adhesiveness. However, this publication does not describe what function the conjugated diene rubber performs when a rubber other than the halogenated ethylene / α-olefin / non-conjugated diene copolymer rubber, for example, a conjugated diene rubber is used in combination. Further, in the examples of the publication, the physical properties of the vulcanizates when mainly using only chlorinated ethylene / α-olefin / non-conjugated diene copolymer rubber alone were measured,
An example in which a conjugated diene rubber is used in combination is a slightly chlorinated ethylene / α-olefin / non-conjugated diene copolymer rubber and SBR.
In Example 6 in which Further, the only example using a brominated ethylene / α-olefin / non-conjugated diene copolymer rubber is Example 5 of the publication, and the bromine content is 1
This is an example in which a material having a high bromine content of 2.3% is used alone. Therefore, as in the present invention, the vulcanization behavior and vulcanization of a composition comprising a combination of a brominated ethylene / α-olefin / non-conjugated diene copolymer rubber and a conjugated diene rubber having a low bromine content of 0.2 to 5% by weight. The publication does not disclose or suggest the physical properties of the substance. Of course, the publication does not disclose or suggest that the composition is suitable for tire sidewalls.

[0006] JP-A-60-47040 discloses that
(A) Halogenated ethylene / α-olefin / non-conjugated diene copolymer rubber having a halogen content of 0.2 to 10% by weight
For a rubber component consisting of 95% by weight and (B) 95 to 5% by weight of a diene rubber, (C) sulfur as a crosslinking agent, (D) guanidine-based vulcanization accelerator as a vulcanization accelerator, and (E) ) A rubber composition containing a specific sulfide compound has been proposed. This proposal is to improve the vulcanization rate and mechanical strength when a halogenated ethylene / α-olefin / non-conjugated diene copolymer rubber and a diene rubber are used in combination by using the component (E). . However, the examples in the publication include chlorinated ethylene α
-Only the evaluation of the composition using the olefin / non-conjugated diene copolymer rubber and the diene rubber in combination was specifically performed, and the brominated ethylene / α-olefin / non-conjugated diene copolymer rubber and the diene rubber were used in combination. Regardless of the use or non-use of the component (E), the rubber composition is silent about what kind of vulcanization behavior and what kind of physical properties the vulcanizate gives. Of course, this publication does not disclose or suggest that a rubber composition using a brominated ethylene / α-olefin / non-conjugated diene copolymer rubber and a diene rubber is suitable for a tire sidewall.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ethylene-based copolymer rubber composition for producing a tire sidewall, which has excellent co-vulcanizability of an ethylene-based copolymer rubber and a conjugated diene-based rubber. Is to provide. Another object of the present invention is to provide a tire sidewall excellent in weather resistance (heat aging resistance) and ozone resistance while substantially maintaining the original mechanical properties and dynamic fatigue resistance characteristics of a conjugated diene rubber vulcanizate. An object of the present invention is to provide an ethylene-based copolymer rubber composition for producing a rubber.

[0008]

According to the present invention, there is provided (A) a brominated ethylene system having a bromine content of 0.2 to 5% by weight obtained by brominating a copolymer rubber of ethylene, α-olefin and non-conjugated polyene. The copolymer rubber and (B) the conjugated diene rubber are mixed in a weight ratio ((A) brominated ethylene copolymer rubber /
(B) a diene rubber) in a ratio of 50/50 to 10/90 in a brominated ethylene copolymer rubber composition for producing tire sidewalls (hereinafter referred to as "rubber for tire sidewall"). The composition is also referred to as "composition") to achieve the above object of the present invention. The present invention is described in detail below, and other objects, advantages and effects of the present invention will become apparent.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The brominated ethylene copolymer rubber (A) used in the present invention has a bromine content of 0.2 to 5% by weight, preferably 0.4 to 4% by weight. If the bromine content is less than 0.2% by weight, sufficient co-vulcanizability with the (B) diene rubber cannot be obtained during vulcanization. On the other hand, if the bromine content exceeds 5% by weight, the processability of the rubber composition for a tire sidewall deteriorates, and the weather resistance and ozone resistance of the produced tire sidewall decrease.

The ethylene copolymer rubber used in the production of the brominated ethylene copolymer rubber (A) of the present invention is an ethylene / α-olefin / conjugated polyene copolymer rubber. As the α-olefin of the ethylene copolymer rubber, an α-olefin having 3 to 12 carbon atoms is preferable, for example, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-pentene. Heptene, 5-methyl-1-hexene, 1-octene, 1-nonene, 5-ethyl-1-hexene, 1-decene, 1-dodecene, 3-methyl-1-butene and the like, preferably propylene, 1-butene, 1-
Hexene, 1-octene is used. These α-olefins can be used alone or in combination of two or more.

The molar ratio of ethylene to α-olefin (ethylene / α-olefin) in the ethylene copolymer rubber is as follows:
40 / 60-90 / 10, preferably 55 / 45-85
/ 15. If the molar ratio is less than 40/60, the mechanical strength of the manufactured tire sidewall is not sufficient, and if it exceeds 90/10, the rubber elasticity of the tire sidewall is impaired.

The non-conjugated polyene specifically includes 5-ethylidene-2-norbornene, dicyclopentadiene, tricyclopentadiene, 5-methyl-2,
5-norbonadiene, 5-methylene-2-norbornene, 5-isopropenyl-2-norbornene, 5- (1
-Butenyl) -2-norbornene, cyclooctadiene, vinylcyclohexene, 1,5,9-cyclododecatriene, 6-methyl-4,7,8,9-tetrahydroindene, 2,2′-dicyclopentenyl, trans −
1,2-divinylcyclobutane, 2-methyl-1,4-
Hexadiene, 1,6-octadiene, 1,7-octadiene, 1,4-hexadiene, 1,8-nonadiene,
1,9-decadiene, 3,6-dimethyl-1,7-octadiene, 4,5-dimethyl-1,7-octadiene,
1,4,7-octatriene, 5-methyl-1,8-nonadiene, dicyclooctadiene, methylene norbornene, 5-vinyl-2-norbornene, 5-methyl-1,5-
Heptadiene, 6-methyl-1,5-heptadiene, 6-methyl-1,6-octadiene, 7-methyl-1,6-octadiene, 5,7-dimethyl-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, 1
2-methyl-1,11-tridecadiene, 13-methyl-1,
11-tridecadiene, 12-methyl-1,12-tetradecadiene, 13-methyl-1,12-tetradecadiene, 1
3-methyl-1,13-pentadecadiene, 14-methyl-
1,13-pentadecadiene and the like can be mentioned.

Among these non-conjugated polyenes, preferably 5-ethylidene-2-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, 1,9-decadiene, 1,4-hexadiene, 6-methyl-1 , 5-heptadiene, 7-methyl-1,6-octadiene, 5,7-dimethyl-1,6-octadiene, 8-methyl-1,7-nonadiene, 9-methyl-1,8-decadiene, especially Preferably, they are 5-ethylidene-2-norbornene, dicyclopentadiene, 1,9-decadiene, 7-methyl-1,6-octadiene, and 5,7-dimethyl-1,6-octadiene.

[0014] These non-conjugated polyenes can be used alone or in combination of two or more.

The iodine value of the ethylene copolymer rubber ranges from 5 to 45, preferably from 10 to 35, and more preferably from 10 to 25. In this case, if the iodine value is less than 5, the mechanical strength of the tire sidewall is inferior, while if it exceeds 45, the rubber elasticity is impaired.

Further, the Mooney viscosity of the ethylene copolymer rubber (ML1 + 4,100 ° C.) (hereinafter simply referred to as “Mooney viscosity”)
That. ) Is 15-200, preferably 20-150
In the range. In this case, if the Mooney viscosity is less than 15, the mechanical strength is poor, while if it exceeds 200, the processing characteristics are poor.

The ratio [Mw / Mn (molecular weight distribution)] between the weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of polystyrene measured by gel permeation chromatography (GPC) of the ethylene copolymer rubber is 1 .
It is in the range of 8-15, preferably 2.5-10.

The above-mentioned ethylene copolymer rubber is produced by copolymerizing ethylene, α-olefin and polyene in the presence of a polymerization catalyst by an appropriate method such as a gas phase polymerization method, a solution polymerization method, a slurry polymerization method and the like. be able to. These polymerization operations can be carried out in a batch system or a continuous system. In the above solution polymerization method or slurry polymerization method, an inert hydrocarbon is usually used as a reaction medium. Examples of such an inert hydrocarbon solvent include aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane, n-decane and n-dodecane;
Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and aromatic hydrocarbons such as benzene, toluene and xylene. These hydrocarbon solvents can be used alone or in combination of two or more. Further, the raw material monomer can be used as a hydrocarbon solvent.

V, Ti, Zr and H are used as polymerization catalysts for producing the ethylene copolymer rubber.
and an olefin polymerization catalyst comprising a compound of a transition metal selected from f and an organometallic compound. The transition metal compound and the organometallic compound can be used alone or in combination of two or more.

Particularly preferred examples of such olefin polymerization catalysts include conventional Ziegler catalysts such as soluble vanadium compounds and organoaluminum compounds, and metallocene compounds and organoaluminum compounds, which are included in the concept of Ziegler catalysts. Alternatively, a metallocene-based catalyst comprising an ionic compound which forms an ionic complex by reacting with the metallocene compound may be used.

Examples of the vanadium compound forming the Ziegler catalyst include vanadium tetrachloride, vanadium oxytrichloride, vanadium triacetylacetonate, vanadium trialkoxide, and vanadium alkoxide halide. Examples of the organoaluminum compound include: Examples include triethylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, and triisobutylaluminum.

On the other hand, examples of the metallocene-based catalyst include a catalyst comprising the following components (E) and (F) or a catalyst comprising the following components (G) and (H).

The component (E) is a transition metal compound represented by the following general formula [1]. R ''s (C5Rm) p (R'nE) q MQ4-pq ... [1] wherein M is a metal of Group 4 of the periodic table, and (C5Rm) is a cyclopentadienyl group Or a substituted cyclopentadienyl group, wherein each R may be the same or different, and is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, or an alkaryl group having 7 to 40 carbon atoms. Or an aralkyl group having 7 to 40 carbon atoms, or two adjacent carbon atoms are bonded to each other to form a 4- to 8-membered carbocyclic ring, and E is an atom having a non-bonded electron pair; 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 a
40 is an aralkyl group, R '' is an alkylene group having 1 to 20 carbon atoms, dialkylsilicon or dialkylgermanium, which is a group binding two ligands,
Is 1 or 0; when s is 1, m is 4; n is a number smaller than the valence of E by 2; when s is 0, m is 5,
n is one less than the valence of E, and when n ≧ 2, each R ′ may be the same or different, each R ′ may be bonded to form a ring, and Q is 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 0 to 4
And satisfies the relationship 0 <p + q ≦ 4.

Specific examples of component (E) include 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 dichloride, bis (indenyl) zirconium dimethyl, dimethylsilylbis (indenyl) zirconium dichloride, methylenebis (indenyl) zircon Umujikurorido, bis (4,
5,6,7-tetrahydroindenyl) zirconium dichloride, bis (4,5,6,7-tetrahydroindenyl) zirconium dimethyl, dimethylsilylbis (4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride , Dimethylsilylbis (4,5
6,7-tetrahydro-1-indenyl) zirconium dimethyl, ethylenebis (4,5,6,7-tetrahydro-1-indenyl) zirconium dichloride, bis (methylcyclopentadienyl) zirconium dichloride, bis (methylcyclopentadiene) Enyl) zirconium dimethyl, dimethylsilyl bis (3-methyl-1-cyclopentadienyl) zirconium dichloride, methylene bis (3-methyl-1-cyclopentadienyl) zirconium dichloride, bis (tertiary butylcyclopentadienyl) Zirconium dichloride, dimethylsilylbis (3-tert-butyl-1-cyclopentadienyl) zirconium dichloride, bis (1,3-dimethylcyclopentadienyl) zirconium dichloride, dimethylsilylbis (2,4-di Chill-1-cyclopentadienyl) zirconium dichloride, bis (1,2,4-trimethyl cyclopentadienyl) zirconium dichloride, dimethyl silyl bis (2,3,5-trimethyl -1
-Cyclopentadienyl) zirconium dichloride, bis (fluorenyl) zirconium dichloride, dimethylsilylbis (fluorenyl) zirconium dichloride,
(Fluorenyl) (cyclopentadienyl) zirconium dichloride, dimethylsilyl (fluorenyl) (cyclopentadienyl) zirconium dichloride, isopropylene (fluorenyl) (cyclopentadienyl) zirconium dichloride, (tertiary butylamide) (1,
2,3,4,5-pentamethylcyclopentadienyl)
Zirconium dichloride, dimethylsilyl (tertiary butylamide) (2,3,4,5-tetramethyl-1-cyclopentadienyl) zirconium dichloride, methylene (tertiary butylamide) (2,3,4,5-tetra Methyl-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 (dimethylamide) zirconium dichloride, bis (diethylamide)
Zirconium dichloride, bis (di-tert-butylamide) zirconium dichloride, dimethylsilylbis (methylamide) zirconium dichloride, dimethylsilylbis (tertiary-butylamide) zirconium dichloride, or the like, or zirconium in these compounds was replaced with titanium or hafnium Compounds include, but are not limited to. Component (E) is
They can be used alone or in combination of two or more.

The component (F) is an aluminoxane compound having a unit represented by the following general formula [2], and although its chemical structure is not necessarily clear, a linear, cyclic or cluster compound, Alternatively, it is presumed to be a mixture of these compounds. -[Al (R) -O]-... [2] wherein R is an alkyl group having 1 to 20 carbon atoms, and 6 to 4 carbon atoms.
An aryl group having 0, 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, an isobutyl group, and particularly preferably a methyl group.

The aluminoxane compound can be produced by a known method involving a reaction between the above-mentioned organoaluminum compound having at least one R group and water.

The proportion of the components (E) and (F) used is usually a molar ratio of a transition metal to an aluminum atom,
1: 1 to 1: 100,000, preferably 1: 5 to 1: 5
0000.

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

R ″ s (C5Rm) p (R ′ n E) q MR ″ ′ 4-pq ... [3] In the formula, M is a metal of Group 4 of the periodic table, and (C5 Rm ) Is a cyclopentadienyl group or a substituted cyclopentadienyl group, and each R may be the same or different and includes a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, 7 is an alkaryl group having 7 to 40 or an aralkyl group having 7 to 40 carbon atoms, or two adjacent carbon atoms are bonded to form a 4- to 8-membered carbocyclic 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 a carbon atom having 7 to 40 carbon atoms.
40 is an aralkyl group, R '' is an alkylene group having 1 to 20 carbon atoms, dialkylsilicon or dialkylgermanium, which is a group binding two ligands,
Is 1 or 0; when s is 1, m is 4; n is a number smaller than the valence of E by 2; when s is 0, m is 5,
n is a number less than the valence of E, and when n ≧ 2, each R ′ may be the same or different, and each R ′ may be bonded to form a ring; Is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, and 7 to
An alkaryl group of 40 or an aralkyl group of 7 to 40 carbon atoms, p and q are integers of 0 to 3,
<P + q ≦ 4.

Specific examples of component (G) include bis (cyclopentadienyl) zirconium dimethyl, bis (cyclopentadienyl) zirconium diethyl, bis (cyclopentadienyl) zirconium diisobutyl, and bis (cyclopentadienyl). Zirconium diphenyl, bis (cyclopentadienyl) zirconium di {bis (trimethylsilyl) methyl}, dimethylsilylbis (cyclopentadienyl) zirconium dimethyl, dimethylsilylbis (cyclopentadienyl) zirconium diisobutyl, methylenebis (cyclopentadienyl) ) Zirconium dimethyl, ethylene bis (cyclopentadienyl) zirconium dimethyl, bis (indenyl) zirconium dimethyl, bis (indenyl) zirconium diisobutyl, dimethyl Rubis (indenyl) zirconium dimethyl, methylenebis (indenyl) zirconium dimethyl, ethylenebis (indenyl) zirconium dimethyl, bis (4,5,6,7-tetrahydroindenyl) zirconium dimethyl, dimethylsilylbis (4,5,6,7 -Tetrahydro-1-indenyl) zirconium dimethyl, ethylenebis (4,5,6,7-
Tetrahydro-1-indenyl) zirconium dimethyl, bis (methylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (3-methyl-1-cyclopentadienyl) zirconium dimethyl, bis (third
Tert-butylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (3-tert-butyl-1-cyclopentadienyl) zirconium dimethyl, bis (1,
3-dimethylcyclopentadienyl) zirconium dimethyl, bis (1,3-dimethylcyclopentadienyl)
Zirconium diisobutyl, dimethylsilylbis (2,
4-dimethyl-1-cyclopentadienyl) zirconium dimethyl, methylenebis (2,4-dimethyl-1-cyclopentadienyl) zirconium dimethyl, ethylenebis (2,4-dimethyl-1-cyclopentadienyl)
Zirconium dimethyl, bis (1,2,4-trimethylcyclopentadienyl) zirconium dimethyl, dimethylsilylbis (2,3,5-trimethyl-1-cyclopentadienyl) zirconium dimethyl, bis (fluorenyl) zirconium dimethyl, dimethyl Silylbis (fluorenyl) zirconium dimethyl, (fluorenyl)
(Cyclopentadienyl) zirconium dimethyl, dimethylsilyl (fluorenyl) (cyclopentadienyl)
Zirconium dimethyl, isopropylene (fluorenyl) (cyclopentadienyl) zirconium dimethyl,
(Tertiary butylamide) (1,2,3,4,5-pentamethylcyclopentadienyl) zirconium dimethyl,
Dimethylsilyl (tertiary butylamide) (2,3,4
5-tetramethyl-1-cyclopentadienyl) zirconium dimethyl, methylene (tertiary butylamide)
(2,3,4,5-tetramethyl-1-cyclopentadienyl) zirconium dimethyl, (phenoxy) (1,
2,3,4,5-pentamethylcyclopentadienyl)
Zirconium dimethyl, dimethylsilyl (o-phenoxy) (2,3,4,5-tetramethyl-1-cyclopentadienyl) zirconium dimethyl, 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 ( Examples include, but are not limited to, tertiary butylamido) zirconium dimethyl, and compounds in which zirconium in these compounds is replaced with titanium or hafnium. Component (G) can be used alone or in combination of two or more.

The transition metal alkyl compound may be synthesized in advance and used, or may be a transition metal halide in which R ″ in the above general formula [3] is substituted with a halogen atom, and trimethylaluminum, triethylaluminum, diethyl ether or the like. It may be formed by bringing an organic metal compound such as aluminum monochloride, triisobutylaluminum, methyllithium, and butyllithium into contact with each other in a 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, and M 'is a periodic table. A group 13-15 element;
An is a hydrogen atom, a halogen atom, a carbon number of 1 to 2
0 alkyl group, C1-C30 dialkylamino group, C1-C20 alkoxy group, C6-C40 aryl group, C6-C40 aryloxy group, C7-C40 alka A reel group, an aralkyl group having 7 to 40 carbon atoms, a halogen-substituted hydrocarbon group having 1 to 40 carbon atoms, an acyloxy group having 1 to 20 carbon atoms, or an organic metalloid group; Is an integer, p is an integer of 1 or more, and q = (k × p).

Specific examples of the component (H) include trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, tributylammonium tetraphenylborate, ammonium (dibutyl) ammonium tetraphenylborate, dimethylanilinium tetraphenylborate, and tetraphenylborate. Methylpyridinium, methyl tetraphenylborate (2-cyanopyridinium), methyl tetraphenylborate (4-cyanopyridinium), trimethylammonium tetrakis (pentafluorophenyl) borate, triethylammonium tetrakis (pentafluorophenyl) borate,
Tributylammonium tetrakis (pentafluorophenyl) borate, methyl (dibutyl) ammonium tetrakis (pentafluorophenyl) borate, dimethylanilinium tetrakis (pentafluorophenyl) borate, methylpyridinium tetrakis (pentafluorophenyl) borate, tetrakis (pentafluorophenyl) Methyl borate (2-cyanopyridinium), tetrakis (pentafluorophenylphenyl) methyl borate (4-cyanopyridinium), tetrakis [bis (3
5-Di-trifluoromethyl) phenyl] dimethylanilinium borate, ferrocenium tetraphenylborate, silver tetraphenylborate, ferrocenium tetrakis (pentafluorophenyl) borate, and the like, but are not limited thereto. Component (H) can be used alone or in combination of two or more.

The use ratio of the above components (G) and (H) is usually 1: 0.5 to 1:20, preferably 1: 0.8 to 1:10, in molar ratio.

The polymerization catalyst used for producing the ethylene copolymer rubber can be used by supporting at least a part of those components on a suitable carrier. The type of carrier is not particularly limited, and any of inorganic oxide carriers, other inorganic carriers, and organic carriers can be used. There is no particular limitation on the loading method, and a known method may be appropriately used.

The above-mentioned ethylene copolymer rubber, that is, ethylene / α-olefin / non-conjugated polyene copolymer rubber is brominated to obtain a brominated ethylene / α-olefin / non-conjugated polyene copolymer (hereinafter referred to as “brominated”). The method for obtaining the “copolymer” is not particularly limited, but is usually produced as follows.

The bromination is carried out by ethylene / α-olefin / non-conjugated polyene copolymer rubber (hereinafter also referred to as “copolymer rubber”), a hydrocarbon such as n-hexane or n-heptane, or carbon tetrachloride or tetrachloroethylene. The reaction is carried out by dissolving the copolymer in a halogenated hydrocarbon such as chlorobenzene, forming a uniform solution, and contacting it with molecular bromine, or by using an organic brominating agent such as N-bromosuccinimide.

During the bromination reaction, ultraviolet rays may be irradiated or a peroxide may be added to accelerate the reaction.

After the bromination reaction, for example, the reaction product is neutralized with an aqueous sodium hydroxide solution, washed with water, and then subjected to steam stripping to obtain a brominated copolymer.

An acid acceptor, an antioxidant, and a metal deactivator are added to these brominated copolymers, respectively.
It is preferable to add about 0.05 to 2 parts by weight based on parts by weight.

Examples of the acid acceptor include organic acid salts of Group IIA metals such as magnesium stearate, calcium stearate, manaceite, hydrotalcite, epoxidized soybean oil, epoxy acid absorbers and the like. As the agent, di-t-butylhydroxytoluene,
Tetrakis [methylene (3,5-di-t-butyl-4-
Hydroxy) hydrocinnamate] methane, d, l-α
Metal inerting agents such as tocopherol, phenyl-β-naphthylamine, triphenylmethane, 1,4-benzoquinone, and the like; tris (nonylphenyl) phosphite, isopropyl citrate, pentaerythritol, tetrakis (2,4-di- t-butylphenyl)-
4,4'-biphenylene-di-phosphite and the like can be exemplified.

In the present invention, (B) the conjugated diene rubber is
In addition to the so-called conjugated diene rubber, it is used as a concept including a hydrogenated polymer of a conjugated diene rubber. Examples of the (B) conjugated diene rubber include natural rubber,
Styrene / butadiene rubber, polybutadiene rubber, acrylonitrile / butadiene rubber, polyisoprene rubber and the like, and hydrogenated polymers thereof are preferable, and natural rubber, styrene / butadiene rubber, polybutadiene rubber, and polyisoprene rubber are preferably used. The hydrogenation rate of the hydrogenated polymer is usually 20 to 99%, preferably 50 to 95%. These (B) conjugated diene rubbers can be used alone or in combination of two or more.

(B) The Mooney viscosity of the conjugated diene rubber is preferably from 10 to 100, more preferably from 20 to 100.
80. If it is less than 10, the mechanical strength of the tire side wall is inferior, while if it exceeds 100, the processing properties of the rubber composition for the tire side wall are inferior, which is not preferable.

The weight ratio of the brominated ethylene copolymer rubber (A) and the conjugated diene rubber (B) contained in the rubber composition for a tire sidewall of the present invention is the weight ratio ((A) / (B)), 50/50 to 10/90, preferably 40/60 to 15/85, and more preferably 40/50 to 10/90.
/ 60 to 20/80. In this case, if the weight ratio is less than 10/90, the ozone resistance of the tire side wall is reduced, and if it exceeds 50/50, the mechanical strength of the tire side wall may be insufficient. Not preferred.

The rubber composition for a tire sidewall of the present invention contains (C) a vulcanizing agent and / or a crosslinking agent for co-vulcanizing the rubber component. (C) a vulcanizing agent and / or
Alternatively, among the crosslinking agents, examples of the vulcanizing agent include sulfur such as powdered sulfur, precipitated sulfur, colloidal sulfur, and insoluble sulfur;
Inorganic vulcanizing agents such as sulfur chloride, selenium and tellurium; and sulfur-containing organic compounds such as morpholine disulfide, alkylphenol disulfides, thiuram disulfides and dithiocarbamates. These vulcanizing agents can be used alone or in combination of two or more. The compounding amount of the vulcanizing agent in the present invention,
Usually, 0.1 to 0.1 parts by weight based on 100 parts by weight of the total of (A) the brominated ethylene copolymer rubber and (B) the conjugated diene rubber.
It is 10 parts by weight, preferably 0.5 to 5 parts by weight.

A vulcanization accelerator can be used together with the vulcanizing agent. Examples of the vulcanization accelerator include aldehyde ammonias such as hexamethylenetetramine; diphenylguanidine, di (o-tolyl) guanidine, o
-Guanidines such as trilupiguanide; thioureas such as thiocarbanilide, di (o-tolyl) thiourea, N, N'-diethylthiourea, tetramethylthiourea, trimethylthiourea, dilaurylthiourea; mercaptobenzothiazol , Dibenzothiazole disulfide, 2- (4-morpholinothio) benzothiazole, 2- (2,4-dinitrophenyl) -mercaptobenzothiazole, (N, N'-diethylthiocarbamoylthio) benzothiazole, etc. Thiazoles;
Nt-butyl-2-benzothiazylsulfenamide, N, N'-dicyclohexyl-2-benzothiazylsulfenamide, N, N'-diisopropyl-2-benzothiazylsulfenamide, N-cyclohexyl −
Sulfenamides such as 2-benzothiazylsulfenamide; thiurams such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetra-n-butylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide; dimethyl Zinc thiocarbamate, zinc diethylthiocarbamate, zinc di-n-butylthiocarbamate, zinc ethylphenyldithiocarbamate, sodium dimethyldithiocarbamate, copper dimethyldithiocarbamate, tellurium dimethylthiocarbamate, iron dimethylthiocarbamate, etc. Carbamates; xanthates such as zinc butylthioxanthate; and the like. These vulcanization accelerators can be used alone or in combination of two or more.

The compounding amount of the vulcanization accelerator is a total of 1 (A) brominated ethylene copolymer rubber and (B) conjugated diene rubber.
The amount is usually 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight based on 00 parts by weight.

[0048] In addition to the above vulcanizing agents and vulcanization accelerators, vulcanization accelerating auxiliaries can be added as required. Examples of the vulcanization accelerating aid include metal oxides such as magnesium oxide, zinc white, litharge, lead red, lead white;
Examples thereof include organic acids (salts) such as stearic acid, oleic acid, and zinc stearate. Zinc white and stearic acid are particularly preferable. These vulcanization accelerators can be used alone or in combination of two or more. The compounding amount of the vulcanization accelerator is usually 0.5 to 20 parts by weight based on 100 parts by weight of the total of (A) the brominated ethylene copolymer rubber and (B) the conjugated diene rubber.

On the other hand, examples of the crosslinking agent (C) include 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, di-tert-butyl peroxide,
Organic peroxides such as dicumyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and 1,3-bis (t-butylperoxy-isopropyl) benzene And the like. These crosslinking agents can be used alone or in combination of two or more. The compounding amount of the crosslinking agent is usually 0.1 part by weight based on 100 parts by weight of the total of (A) the brominated ethylene copolymer rubber and (B) the conjugated diene rubber.
It is 1 to 15 parts by weight, preferably 0.5 to 10 parts by weight.

A crosslinking aid can be used together with the above-mentioned crosslinking agent. Examples of the crosslinking assistant include sulfur and sulfur or a sulfur compound such as dipentamethylenethiuram tetrasulfide; ethylene di (meth) acrylate, polyethylene di (meth) acrylate, divinylbenzene, diallyl phthalate, triallyl cyanurate, and metaphenylene bis. Polyfunctional monomers such as maleimide and toluylenebismaleimide; p-quinone oxime,
Oxime compounds such as p, p'-benzoylquinone oxime. These crosslinking aids can be used alone or in combination of two or more. The amount of the crosslinking aid is usually 0.5 to 20 parts by weight based on 100 parts by weight of the total of (A) the brominated ethylene copolymer rubber and (B) the conjugated diene rubber.

The rubber composition for a tire sidewall according to the present invention may optionally contain a filler, a softener, an acid acceptor and an antioxidant.

As the filler, for example, SRF, F
Examples include carbon black such as EF, HAF, ISAF, SAF, FT, and MT, and inorganic fillers such as white carbon, fine particles of magnesium silicate, calcium carbonate, magnesium carbonate, clay, and talc. These fillers can be used alone or in combination of two or more. The amount of the filler is usually 10 to 200 parts by weight, based on 100 parts by weight of the total of (A) the brominated ethylene-based copolymer rubber and (B) the conjugated diene-based rubber.
Preferably it is 10 to 100 parts by weight.

Examples of the softener include aromatic oils and naphthenic oils commonly used for rubbers.
Examples include process oils such as paraffin oil, vegetable oils such as coconut oil, and synthetic oils such as alkylbenzene oil. Of these, process oils are preferred, and paraffin oil is particularly preferred. The above softeners can be used alone or in combination of two or more. In the present invention, the compounding amount of the softener is a total amount of (A) the brominated ethylene-based copolymer rubber and (B) the conjugated diene-based rubber of 1
It is usually 10 to 130 parts by weight, preferably 20 to 100 parts by weight, based on 00 parts by weight.

The acid acceptors that can be used in the present invention include organic acid salts of metals of Group IIA of the periodic table, such as magnesium stearate, calcium stearate, manasseotho, hydrotalcite, epoxidized soybean oil, epoxy acid absorption Metal oxides such as magnesium and lead,
Metal hydroxides and the like are widely used.

As the antioxidants usable in the present invention, naphthylamines, diphenylamines, p-phenylenediamines, quinolines, hydroquinone derivatives, mono,
Examples include bis, tris, polyphenol, thiobisphenol, hindered phenol, phosphite, imidazole, nickel dithiocarbamate, and phosphoric acid antioxidants. These may be used alone or in combination of two or more.

Further, the rubber composition for a tire sidewall of the present invention comprises a non-brominated ethylene / α-olefin / polyene copolymer, an ethylene / α-olefin copolymer,
Other rubbers or resins such as polyethylene and polypropylene may be used alone or in combination of two or more.

In addition, the rubber composition for a tire sidewall according to the present invention includes an ultraviolet absorber, a light stabilizer, a flame retardant, an antistatic agent, a conductive plasticizer, a liquid rubber, a functional group-containing oligomer, and a colorant. , Arbitrarily compounding oil resistance improver, foaming agent, anti-scorch agent, tackifier, dewatering agent, activator, wax, coupling agent, mastication accelerator, antibacterial agent, foaming aid, processing aid, etc. it can.

In preparing the rubber composition for a tire side wall of the present invention, a conventionally known kneader, extruder,
A vulcanizing device or the like can be used. The compounding method and order of the vulcanizing agent and / or crosslinking agent, filler, softening agent and the like mixed with (A) the brominated ethylene copolymer rubber or (B) the conjugated diene rubber are, for example, Banbury. Using a mixer or the like, (A) a method of mixing an ethylene copolymer rubber or a conjugated diene rubber, a filler, a softener, etc., and then adding a vulcanizing agent and / or a crosslinking agent using a roll or the like. However, the present invention is not limited to this.

Next, vulcanization is carried out by, for example, placing the rubber composition in a mold and raising the temperature, or using an extruder by a method commonly used in the manufacture of tire sidewalls. After molding into a predetermined shape by heating and vulcanizing by heating in a vulcanizing tank, a tire sidewall can be manufactured.

[0060]

The present invention will now be described more specifically with reference to examples. However, the present invention is not limited to these embodiments. The percentages and parts in the examples are on a weight basis unless otherwise specified. The measurement and evaluation in Examples and Comparative Examples were performed by the following methods. (A) α-Olefin content (mol%) Measured by ¹³ C-NMR method. However, the content (mol%) of ethylene and α-olefin in each of Examples and Comparative Examples is a value when the total amount of these is 100 mol%. (Ii) Iodine value It was measured by an infrared absorption spectrum method. (C) Raw rubber Mooney viscosity (ML1 + 4,100 ° C.) Measured at 100 ° C., 1 minute preheating, and 4 minutes measurement in accordance with JIS K6300. (D) Measured by GPC in Mw / Mn o-dichlorobenzene at 135 ° C.

(E) Bromine content The bromine content was measured by elemental analysis by fluorescent X-ray analysis. (F) Compounded rubber Mooney viscosity (ML1 + 4,100 ° C) (hereinafter referred to as “Compd MV”)
According to JIS K6300, the measurement was performed under the conditions of a measurement temperature of 100 ° C., a preheating of 1 minute, and a measurement of 4 minutes. (G) Vulcanization property test Using a Curastometer V type manufactured by Nippon Synthetic Rubber Co., Ltd., a 10% increase in the difference between the maximum torque value and the minimum value from the vulcanization curve at 160 ° C. for 30 minutes. Was obtained as t'c (10), and the time required for obtaining a 90% increase in value was obtained as t'c (90). (H) Tensile test According to JIS K6301, using a No. 3 type test piece, at a measurement temperature of 25 ° C. and a tensile speed of 500 mm / min, the tensile strength TB (MPa) and the tensile elongation at break EB (%) It was measured. (I) Hardness test According to JIS K6301, the spring hardness (JIS
A hardness).

(V) Heat aging resistance According to JIS K6301, the tensile strength (Tb) and the elongation at the time of tensile cutting (Eb) of the vulcanized rubber after heat aging under the following conditions were measured, and before heat aging. Tb and Eb of vulcanized rubber
The ratio (%) to the breaking strength retention rate Ar (T
b), expressed as the elongation at break retention Ar (Eb). Aging conditions: 160 ° C., 70 hours, in an air oven (l) Elongation fatigue test (crack growth) A No. 2 type dumbbell test piece described in JIS K6301 was prepared, and a crack was previously formed in the longitudinal center of the test piece. Ten test pieces were subjected to elongation fatigue under the conditions of an elongation ratio of 50%, a measurement temperature of 30 ° C., and a rotation speed of 300 cpm.
The average value of the number of cycles until the test piece was cut was determined. (ヲ) Ozone resistance test Ozone concentration 50 pph in accordance with JIS-K6301
The crack generation time was measured under the conditions of m, 40 ° C., and elongation rate of 30%, and was used as an index of ozone resistance. The test period was 14 days.

REFERENCE EXAMPLE 1 ((A) Production of Brominated Ethylene Copolymer Rubber 1) A continuous flow stirred tank reactor having a capacity of 40 L having a supply port at the bottom and a discharge port at the top was supplied with a supply temperature of -30. ° C, n-hexane feed rate 230 L / hour, ethylene feed rate 5.8 k
g / h, propylene feed rate 14.5 kg / h, 5-
Ethylidene-2-norbornene (ENB) supply 0.5
8 kg / hour and a hydrogen supply rate of 2.0 g / hour were supplied. The vanadium catalyst component was prepared by adding 1.5 times the molar ratio of 1-butanol to vanadium oxytrichloride (VOCl3) outside the reactor in advance and dehydrochlorinating with nitrogen gas. 21 mmol / L
Prepared in hexane and added. Using ethyl aluminum sesquichloride as the organic aluminum compound,
Adjusted to a concentration of 0.53 mmol / L hexane and added,
The polymerization reaction was carried out under the conditions of a polymerization temperature of 50 ° C. and a polymerization pressure of 10 kg / cm ² -G. A small amount of water was added as a reaction terminator to the polymerization solution withdrawn from the reactor to remove residual catalyst,
After a small amount of an antioxidant was added, the solvent was driven out of the system by steam stripping and dried in the finishing step. The raw rubber properties of the obtained rubber are the Mooney viscosity (ML1 + 4,10
0 ° C) 65, ethylene content 66.6 mol%, propylene content 33.4 mol%, iodine value 15.0, Mw / Mn
3.4 (hereinafter referred to as “EP”).
(1) "). 150 g of EP (1) was dissolved in 6.7 L of n-hexane, and the solution was charged into a glass reactor equipped with a reflux condenser, a stirrer and a thermometer.
The mixture was kept at 0 ° C and stirred. An n-hexane solution of bromine (5.7 g as bromine) was added dropwise, and the mixture was stirred for 1 hour, neutralized by adding a dilute aqueous solution of sodium hydroxide, and the solvent was removed by steam stripping. It was dried to obtain a brominated ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber having a bromine content of 2.0% (hereinafter referred to as "Br-EP (1)").

Reference Example 2 (Production of Chlorinated Ethylene Copolymer Rubber) The same operation as in Reference Example 1 was carried out to chlorinate EP (1) to give a chlorinated ethylene / propylene / chloride having a chlorine content of 2.0%.
5-ethylidene-2-norbornene copolymer rubber (hereinafter, referred to as "5-ethylidene-2-norbornene copolymer rubber")
"Cl-EP (1)").

Reference Example 3 ((A) Production of Brominated Ethylene Copolymer Rubber 2) Into a stainless steel autoclave having a capacity of 3 liters which had been sufficiently purged with nitrogen, 1.45 liters of purified toluene, 460 ml of 1-octene, and 7- After adding 45 ml of methyl-1,6-octadiene and 1.7 ml (8.9 mmol) of 1,9-decadiene, and raising the temperature to 30 ° C., ethylene was continuously supplied at a rate of 14 normal liters / minute. Meanwhile, the internal pressure of the container was adjusted to 5 kg / cm ² .
Separately, isopropylene (fluorenyl) (cyclopentadienyl) zirconium dichloride dissolved in 3.0 ml of purified toluene was placed in a 50 ml glass flask containing a magnetic stirrer and sufficiently purged with nitrogen. 3.0 micromol, purified toluene 6.0
1.5 mmol of triisobutylaluminum dissolved in milliliter was added thereto, and the mixture was stirred and reacted at room temperature for 30 minutes. Next, 3.6 μmol of dimethylanilinium tetrakis (pentafluorophenyl) borate dissolved in 7.2 ml of purified toluene was added, and the mixture was stirred at room temperature for 20 minutes to be reacted to obtain a polymerization catalyst. This polymerization catalyst was added to the above autoclave to start polymerization. During the reaction, the temperature was kept at 30 ° C., while continuously supplying ethylene, the internal pressure of the vessel was kept at 5 kg / cm ² ,
Polymerization was carried out for 15 minutes. Next, a small amount of methanol was added to stop the reaction, and then the mixture was dissolved by steam stripping and dried with a 6-inch roll to obtain 155 g of a polymer. This polymer has an ethylene content of 74.8 mol%, a 1-octene content of 25.2 mol%, and an iodine value of 1
3, Mooney viscosity 53, Mw / Mn 3.1, glass transition point -68.1 ° C, branching index B 0.835 ethylene / 1
-Octene-7-methyl-1,6-octadiene / 1,9-decadiene copolymer rubber (hereinafter also referred to as “EP (2)”). Thereafter, the same operation as in Reference Example 1 was carried out to obtain a bromine content of 2.
0% brominated ethylene / 1-octene-7-methyl-1,
A 6-octadiene / 1,9-decadiene copolymer rubber was obtained. (Hereinafter also referred to as "Br-EP (2)")

Reference Example 4 ((A) Production of Brominated Ethylene Copolymer Rubber 3) The procedure of Reference Example 1 was repeated, except that 10.0 g of bromine in n-hexane was dropped as bromine. As a result, a brominated ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber having a bromine content of 3.8% (hereinafter referred to as "Br-EP (3)") was obtained.

REFERENCE EXAMPLE 5 ((A) Production of Brominated Ethylene Copolymer Rubber 4) The same operation as in Reference Example 1 was carried out except that 1.7 g of bromine in n-hexane was dropped as bromine in Reference Example 1. And a brominated ethylene / propylene / 0.5% bromine content
5-ethylidene-2-norbornene copolymer rubber (hereinafter, referred to as "5-ethylidene-2-norbornene copolymer rubber")
"Br-EP (4)").

Reference Example 6 ((A) Production of Brominated Ethylene Copolymer Rubber 5) The procedure of Reference Example 1 was repeated, except that 14.0 g of bromine in n-hexane was dropped as bromine. As a result, a brominated ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber having a bromine content of 5.4% (hereinafter referred to as "Br-EP (5)") was obtained.

Example 1, Comparative Example 1 (Comparison of vulcanization rate) A rubber compound having the composition shown in Table 1 consisting of a rubber component, a filler, a vulcanizing agent and a stabilizer was heated to 70 ° C. using a 6-inch open roll.
For 20 minutes. 160 ° C of the kneaded rubber compound
× From the vulcanization curve for 30 minutes, t'c (10) and t'c
(90) was determined. The results are shown in the table below.

[0070]

[Table 1]

As is clear from Table 1, t ′ in Example 1
Both c (10) and t′c (90) are shorter than Comparative Example 1, and it can be seen that the vulcanization rate of the brominated polymer is faster than that of the chlorinated polymer.

Examples 2-3 and Comparative Example 2 (Preparation and Evaluation of Rubber Composition) A rubber compound comprising a rubber component, a filler, a vulcanizing agent, and a stabilizer and having the composition shown in Table 2 was used using a 6-inch open roll. 70 ° C
For 20 minutes. 160 ° C of the kneaded rubber compound
For 15 minutes to produce a vulcanized rubber sheet having a thickness of 2 mm. The mechanical properties were measured using this sheet. The results are shown in Table 3.

[0073]

[Table 2]

[0074]

[Table 3]

From the results shown in Table 3, the following is clear. Examples 2 and 3 (rubber compositions for tire sidewalls of the present invention) have rubber-like properties (strength at break,
It provides a vulcanizate with excellent elongation at break, heat aging resistance, elongation fatigue properties (dynamic fatigue properties) and ozone resistance. on the other hand,
Comparative Example 2 (conventional composition containing NR / BR as a rubber component) is excellent in rubber-like properties, but is inferior in heat aging resistance, extension fatigue properties (dynamic fatigue properties) and ozone resistance. Give things.

Examples 4 to 5 and Comparative Examples 3 to 4 In Example 2, (A) the polymer produced in Reference Examples 4 to 6 or the ethylene copolymer before bromination was used as the brominated ethylene copolymer rubber. The same operation as in Example 2 was performed except that the polymer rubber was used. Table 4 shows the results.

[0077]

[Table 4]

From the results shown in Table 4, the following is clear. Examples 2, 4 and 5 (the rubber composition for a tire sidewall of the present invention) have rubber-like properties, heat aging resistance,
It gives a vulcanizate that is excellent in both elongation fatigue properties (dynamic fatigue properties) and ozone resistance. Comparative Example 3 is an example in which the bromine content is too large, and the cohesion by bromine is too strong.
The compounded rubber Mooney viscosity is high, resulting in poor workability, low elongation at break, and poor elongation fatigue properties and ozone resistance. Comparative Example 4 is an example in which an unbrominated ethylene copolymer rubber was used as a rubber component, and was significantly inferior in rubber-like properties and inferior in extension fatigue properties.

Examples 6 and 7 and Comparative Examples 5 and 6 In Example 2, the mixing ratio of natural rubber and (A) brominated ethylene copolymer rubber Br-EP (1) was changed as shown in Table 5. Except having performed, it carried out similarly to Example 2. Table 5 shows the results.

[0080]

[Table 5]

From the results shown in Table 5, the following is clear. Examples 2, 6 and 7 (rubber compositions for tire sidewalls of the present invention) are vulcanizates having excellent rubber properties, heat aging resistance, elongation fatigue properties (dynamic fatigue properties) and ozone resistance. give. On the other hand, Comparative Example 5 is an example in which the blending amount of the brominated ethylene copolymer rubber (A) is too small, and the vulcanizate has excellent rubber-like properties, but is inferior in heat aging resistance and ozone resistance. Comparative Example 6 is an example in which the blending amount of the brominated ethylene copolymer rubber (A) is too large, and is inferior in rubber-like properties and extension fatigue properties (dynamic fatigue properties).

[0082]

The rubber composition for a tire sidewall according to the present invention has excellent co-vulcanizability of a brominated ethylene-based copolymer rubber and a conjugated diene-based rubber. A vulcanized rubber excellent in weather resistance (thermal aging resistance) and ozone resistance is provided while substantially maintaining mechanical characteristics and dynamic fatigue resistance characteristics, so that a high-quality tire sidewall can be manufactured.

Claims (1)

[Claims] 1. A bromine content obtained by brominating a copolymer rubber of (A) ethylene, an α-olefin and a non-conjugated polyene is 0.2.
-5% by weight of a brominated ethylene copolymer rubber and (B) a conjugated diene rubber in a weight ratio of ((A) brominated ethylene copolymer rubber / (B) diene rubber) 50 / 50-10
An ethylene copolymer rubber composition for tire sidewalls, which is contained in an amount of / 90.