JP6702312B2 - Rubber composition, crosslinked rubber and tire - Google Patents

Description

The present invention relates to a rubber composition, and more specifically, it contains a cycloolefin ring-opening copolymer containing a specific structural unit and a styrene-butadiene copolymer, and has improved processability and improved fuel efficiency. The present invention relates to a rubber composition that can be a raw material for manufacturing tires. The present invention also relates to a rubber cross-linked product obtained by cross-linking the above rubber composition, particularly a tire.

Rubber compositions containing conjugated diene rubbers such as butadiene rubber (BR) and styrene-butadiene rubber (SBR) and fillers such as carbon black and silica are widely used as rubber compositions for manufacturing automobile tires. ing.

However, with respect to butadiene, which is a raw material for BR and SBR, it is predicted that the production amount will decrease in recent years. Butadiene is produced as a by-product when ethylene is produced by cracking naphtha, and in recent years, a method of using natural gas such as ethane as a raw material has been expanding as a method for producing ethylene. For this reason, a decrease in butadiene production is predicted. Therefore, various studies have been conducted on the use of synthetic rubber not containing butadiene as a raw material as a substitute material for butadiene rubber or styrene butadiene rubber.

The use of cycloolefin ring-opening polymers such as cyclopentene ring-opening polymers obtained by ring-opening polymerization of cyclopentene is being studied as one type of synthetic rubber that is being investigated as a substitute material for BR and SBR. For example, Patent Document 1 describes a cycloolefin ring-opening copolymer obtained by ring-opening copolymerization of cyclopentene and 1,5,9-cyclododecatriene.

However, 1,5,9-cyclododecatriene has a problem that its cost is higher than that of other cyclic olefin compounds. Further, 1,5,9-cyclododecatriene has a large ring strain due to its chemical structure. Therefore, when copolymerizing with cyclopentene, there is a large difference between the polymerization rate of cyclopentene and the polymerization rate of 1,5,9-cyclododecatriene, and it was difficult to control the copolymerization ratio during polymerization. As a result, there is a problem in that the productivity of the cycloolefin ring-opening copolymer is poor.

International Publication No. 2012/043802

The present invention has been made in view of the above-mentioned prior art, and in a rubber composition using a cycloolefin ring-opening copolymer, it is excellent in cost and productivity, and further improved in processability and low heat buildup. An object is to provide a rubber composition that can be achieved.

As a result of intensive studies to solve the above problems, the present inventors have found that a rubber composition has a cycloolefin ring-opening copolymer containing a cyclopentene-derived structural unit and a cyclooctadiene-derived structural unit, and a styrene-butadiene copolymer. It has been found that the compounding with a polymer is excellent in cost and productivity, and further, the processability of the rubber composition is improved. Furthermore, it has been found that a crosslinked rubber (tire) having excellent low heat buildup can be obtained by crosslinking the rubber composition. The present invention has been completed based on this finding.

The gist of the present invention for solving the above problems is as follows.
[1] A cycloolefin ring-opening copolymer containing a structural unit derived from cyclopentene and a structural unit derived from cyclooctadiene, and a styrene-butadiene copolymer,
In the cycloolefin ring-opening copolymer, the content of structural units derived from cyclopentene in all repeating units is 50 to 99 mol%, the content of structural units derived from cyclooctadiene is 50 to 1 mol%,
A rubber composition in which the weight ratio of the cycloolefin ring-opening copolymer and the styrene-butadiene copolymer (cycloolefin ring-opening copolymer/styrene-butadiene copolymer) is 5/95 to 95/5. object.

[2] The cycloolefin ring-opening copolymer has a functional group containing at the polymer chain terminal at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom, a phosphorus atom, a sulfur atom, and a silicon atom. The rubber composition according to [1], which comprises a cycloolefin ring-opening copolymer having

[3] The rubber composition according to [2], wherein the cycloolefin ring-opening copolymer contains a cycloolefin ring-opening copolymer having an oxysilyl group at the polymer chain end.

[4] The rubber composition according to any one of [1] to [3], wherein the styrene-butadiene copolymer contains a styrene-butadiene copolymer having a modifying group at the polymer chain terminal.

[5] The rubber composition according to any one of [1] to [4], which comprises silica and/or carbon black.

[6] The rubber composition according to any one of [1] to [5], which contains a crosslinking agent.

[7] A rubber cross-linked product obtained by cross-linking the rubber composition according to the above [6].

[8] A tire obtained by using the crosslinked rubber according to the above [7].

[9] A method for producing the rubber composition according to any one of the above [1] to [6],
In the presence of a Group 6 transition metal compound (A) of the periodic table and an organoaluminum compound (B) represented by the following general formula (3), cyclopentene and cyclooctadiene are subjected to ring-opening copolymerization to open a cycloolefin. Obtaining a ring copolymer,
A method for producing a rubber composition, which comprises a step of kneading the cycloolefin ring-opening copolymer and a styrene-butadiene copolymer.
(R ¹ ) _3-a ― _b Al(OR ² ) _a X _b (3)
(In the general formula (3), R ¹ represents a hydrocarbon group having 1 to 20 carbon atoms, R ² represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a halogen atom, X represents a halogen atom, a is 1 or 2, b is 0 or 1, and a+b<3 is satisfied.)

[10] In the step of obtaining the cycloolefin ring-opening copolymer, cyclopentene and cyclooctadiene are subjected to ring-opening copolymerization in the presence of an oxysilyl group-containing olefinically unsaturated hydrocarbon (C). The method for producing the rubber composition according to item 1.

[11] The method for producing a rubber composition according to [9] or [10], further including a step of obtaining a styrene-butadiene copolymer by a solution polymerization method.

According to the present invention, as a rubber composition, by blending a cycloolefin ring-opening copolymer containing a structural unit derived from cyclopentene and a structural unit derived from cyclooctadiene, and a styrene-butadiene copolymer, the cost can be reduced. And excellent productivity, and further the processability of the rubber composition is improved. Further, the rubber cross-linked product obtained by cross-linking the rubber composition is excellent in low heat build-up, and thus the tire using the rubber cross-linked product is excellent in fuel consumption.

(1) Rubber composition The rubber composition according to the present invention comprises a cycloolefin ring-opening copolymer containing a cyclopentene-derived structural unit and a cyclooctadiene-derived structural unit, and a styrene-butadiene copolymer. In the cycloolefin ring-opening copolymer, the content of the structural unit derived from cyclopentene is 50 to 99 mol% and the content of the structural unit derived from cyclooctadiene is 50 to 1 mol% in all repeating units. And the weight ratio of the cycloolefin ring-opening copolymer and the styrene-butadiene copolymer (cycloolefin ring-opening copolymer/styrene-butadiene copolymer) is 5/95 to 95/5.

The rubber composition according to the present invention is excellent in processability because it contains a cycloolefin ring-opening copolymer having a specific amount of a specific structural unit and a styrene-butadiene copolymer in a specific weight ratio. Further, the rubber cross-linked product obtained by cross-linking the rubber composition is excellent in low heat buildup.

(Cycloolefin ring-opening copolymer)
The cycloolefin ring-opening copolymer contains a structural unit derived from cyclopentene and a structural unit derived from cyclooctadiene. The structural unit derived from cyclopentene refers to a structural unit formed by polymerizing cyclopentene. The structural unit derived from cyclooctadiene means a structural unit formed by polymerizing cyclooctadiene. The cycloolefin ring-opening copolymer containing the above structural unit is a linear polymer and is excellent in rubber properties and processability.

From the viewpoint of improving the rubber properties and processability of the rubber composition, and from the viewpoint of obtaining a rubber composition that is a rubber crosslinked product excellent in low heat buildup, in all repeating units in the cycloolefin ring-opening copolymer. The content of the structural unit derived from cyclopentene is preferably 60 to 95 mol %, more preferably 70 to 95 mol %, and the content of the structural unit derived from cyclooctadiene is preferably 40 to 5 mol %. , And more preferably 30 to 5 mol %.

Examples of cyclooctadiene include 1,3-cyclooctadiene and 1,5-cyclooctadiene, and 1,5-cyclooctadiene is preferable from the viewpoint of cost and productivity.

Further, the cycloolefin ring-opening copolymer in the present invention is, in a range that does not impair the intended purpose, optionally a structural unit derived from cyclopentene, and a structural unit derived from cyclooctadiene, a metathesis-reactive It may contain a structural unit derived from another cyclic olefin compound. Examples of such a cyclic olefin compound (hereinafter, sometimes referred to as "other copolymerizable cyclic olefin compound") include norbornene compounds such as 2-norbornene and dicyclopentadiene. The content of the structural unit derived from another cyclic olefin compound having metathesis reactivity is preferably 49 mol% or less, more preferably 35 mol% or less, and further preferably 25 mol% or less.

The weight average molecular weight (Mw) of the cycloolefin ring-opening copolymer is not particularly limited, but is preferably 200,000 to 1,000,000, and more preferably 200,000 to 900,000. By setting the weight average molecular weight of the cycloolefin ring-opening copolymer within the above range, it becomes possible to provide a rubber crosslinked product (for example, a tire) having excellent mechanical properties. If the weight average molecular weight is too low, the rubber properties may be poor. On the other hand, if the weight average molecular weight is too high, production and handling may be difficult.
The weight average molecular weight of the cycloolefin ring-opening copolymer may be appropriately adjusted within the above range according to the purpose of use. The weight average molecular weight in the present invention is a value in terms of polystyrene measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent (the same applies hereinafter).

The ratio (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cycloolefin ring-opening copolymer measured by gel permeation chromatography (GPC) is not particularly limited. Is usually 4.0 or less, preferably 3.5 or less, more preferably 3.0 or less, and usually 1.5 or more. By having such Mw/Mn, it becomes possible to provide a rubber crosslinked product having excellent mechanical properties.

The cis/trans ratio of the double bond present in the structural unit constituting the cycloolefin ring-opening copolymer is not particularly limited, but is usually set in the range of 10/90 to 90/10, and From the viewpoint of improving the rubber properties, the range is preferably 30/70 to 90/10, more preferably 40/60 to 90/10.

The glass transition temperature (Tg) of the cycloolefin ring-opening copolymer is not particularly limited, but is preferably −98° C. or lower, and more preferably −99° C., from the viewpoint of improving rubber properties at low temperatures. Hereafter, the temperature is more preferably −100° C. or lower, and preferably −120° C. or higher. The glass transition temperature (Tg) of the cycloolefin ring-opening copolymer can be controlled by, for example, the cis/trans ratio of double bonds present in the repeating unit.

The cycloolefin ring-opening copolymer may have a melting point (Tm). When the cycloolefin ring-opening copolymer has a melting point, its temperature is preferably 0° C. or lower, and −5° C. or lower, from the viewpoint of improving rubber properties at low temperatures. Is more preferable. The presence or absence of the melting point of the cycloolefin ring-opening copolymer, and the temperature when it has the melting point, should be controlled by the cis/trans ratio of the double bonds present in the repeating unit and the copolymerization ratio of the copolymer. You can

The Mooney viscosity (ML ₁₊₄ , 100° C.) of the cycloolefin ring-opening copolymer is not particularly limited, but is preferably 20 to 150, more preferably 22 to 120, and further preferably 25 to 100. When the Mooney viscosity of the cycloolefin ring-opening copolymer is controlled within the above range, the rubber composition is particularly excellent in processability.

Modified cycloolefin ring-opening copolymer The cycloolefin ring-opening copolymer in the present invention has at least one selected from the group consisting of nitrogen atom, oxygen atom, phosphorus atom, sulfur atom, and silicon atom at the polymer chain terminal. It is preferable to include a cycloolefin ring-opening copolymer having a functional group containing the atom (hereinafter collectively referred to as “terminal functional group”). In the following, a cycloolefin ring-opening copolymer having a terminal functional group may be referred to as a "modified cycloolefin ring-opening copolymer". By introducing a terminal functional group into the polymer chain end of the cycloolefin ring-opening copolymer, the rubber composition according to the present invention, when a filler such as silica or carbon black is blended, with the filler The affinity of is further improved and the dispersibility of the filler is excellent. As a result, it is possible to obtain a rubber composition which is a crosslinked rubber excellent in low heat buildup. From such a viewpoint, among the above-mentioned terminal functional groups, a functional group containing an atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a silicon atom is more preferable.

Examples of the functional group containing a nitrogen atom include an amino group, a pyridyl group, an imino group, an amide group, a nitro group, a urethane bonding group, or a hydrocarbon group containing these groups.

Examples of the functional group containing an oxygen atom include a hydroxyl group, a carboxyl group, an ether group, an ester group, a carbonyl group, an aldehyde group, an epoxy group, or a hydrocarbon group containing these groups.

Examples of the functional group containing a phosphorus atom include a phosphoric acid group, a phosphino group, or a hydrocarbon group containing these groups.

Examples of the functional group containing a sulfur atom include a sulfonyl group, a thiol group, a thioether group, and a hydrocarbon group containing these groups.

Examples of the functional group containing a silicon atom include an alkylsilyl group, an oxysilyl group, and a hydrocarbon group containing these groups.

Further, the terminal functional group may be a functional group containing a plurality of the above groups. Among these, specific examples of particularly preferable functional groups from the viewpoint that the low heat buildup property of the rubber cross-linked product obtained by crosslinking the rubber composition can be further improved, as an amino group, a pyridyl group, an imino group, Examples thereof include an amide group, a hydroxyl group, a carboxyl group, an aldehyde group, an epoxy group, an oxysilyl group, and a hydrocarbon group containing these groups, and an oxysilyl group is particularly preferable.

The oxysilyl group is a group having a silicon-oxygen bond. By introducing an oxysilyl group into the polymer chain terminal of the cycloolefin ring-opening copolymer, the compatibility with fillers such as silica and carbon black compounded in the rubber composition obtained using the copolymer is improved. Improved and excellent in dispersibility of the filler. As a result, it is possible to obtain a rubber composition which is a crosslinked rubber excellent in low heat buildup.

Among the oxysilyl groups, for example, an alkoxysilyl group having a high affinity with silica or carbon black as a filler used when forming a rubber material for a tire and having a high effect of improving low heat buildup, An aryloxysilyl group, an acyloxysilyl group, an alkylsiloxysilyl group and an arylsiloxysilyl group are preferable, and an alkoxysilyl group is more preferable. Further, a hydroxysilyl group obtained by hydrolyzing an alkoxysilyl group, an aryloxysilyl group, or an acyloxysilyl group is also preferable.

The alkoxysilyl group is a group in which one or more alkoxy groups are bonded to a silicon atom, and specific examples thereof include trimethoxysilyl group, (dimethoxy)(methyl)silyl group, (methoxy)(dimethyl)silyl. Group, (methoxy)(dichloro)silyl group, triethoxysilyl group, (diethoxy)(methyl)silyl group, (ethoxy)(dimethyl)silyl group, (dimethoxy)(ethoxy)silyl group, (methoxy)(diethoxy)silyl group Group, tripropoxysilyl group and the like.

The aryloxysilyl group is a group in which one or more aryloxy groups are bonded to a silicon atom, and specific examples thereof include triphenoxysilyl group, (diphenoxy)(methyl)silyl group, (phenoxy)(dimethyl). Examples thereof include a silyl group, a (phenoxy)(dichloro)silyl group, a (diphenoxy)(ethoxy)silyl group, and a (phenoxy)(diethoxy)silyl group. Note that, of these, the (diphenoxy)(ethoxy)silyl group and the (phenoxy)(diethoxy)silyl group have an alkoxy group in addition to the aryloxy group, and are therefore classified as an alkoxysilyl group.

The acyloxysilyl group is a group in which one or more acyloxy groups are bonded to a silicon atom, and specific examples thereof include triacyloxysilyl group, (diacyloxy)(methyl)silyl group, (acyloxy)(dimethyl) Examples thereof include a silyl group and an (acyloxy)(dichloro)silyl group.

The alkylsiloxysilyl group is a group in which one or more alkylsiloxy groups are bonded to a silicon atom, and specific examples thereof include tris(trimethylsiloxy)silyl group, trimethylsiloxy(dimethyl)silyl group, triethylsiloxy( Examples thereof include a diethyl)silyl group and a tris(dimethylsiloxy)silyl group.

The arylsiloxysilyl group is a group in which one or more arylsiloxy groups are bonded to a silicon atom, and specific examples thereof include tris(triphenylsiloxy)silyl group, triphenylsiloxy(dimethyl)silyl group and tris. (Diphenylsiloxy)silyl group and the like.

The hydroxysilyl group is a group in which one or more hydroxy groups are bonded to a silicon atom, and specific examples include trihydroxysilyl group, (dihydroxy)(methyl)silyl group, (hydroxy)(dimethyl)silyl group. , (Hydroxy)(dichloro)silyl group, (dihydroxy)(ethoxy)silyl group, (hydroxy)(diethoxy)silyl group and the like. Note that, of these, the (dihydroxy)(ethoxy)silyl group and the (hydroxy)(diethoxy)silyl group have an alkoxy group in addition to the hydroxy group, and thus are classified as an alkoxysilyl group.

（上記一般式（１）中、Ｒ⁹〜Ｒ¹³は、水素原子、炭素数１〜１０のアルキル基、アリール基、アルコキシ基、アリーロキシ基、アシロキシ基、アルキルシロキシ基、アリールシロキシ基から選択される基である。また、ｐは、１〜１０の整数である。）

（上記一般式（２）中、Ｒ¹⁴〜Ｒ¹⁸は、水素原子、炭素数１〜１０のアルキル基、アリール基、アルコキシ基、アリーロキシ基、アシロキシ基、アルキルシロキシ基、アリールシロキシ基から選択される基である。また、ｑは、１〜１０の整数である。）In addition to the above, a linear polysiloxane group represented by the following general formula (1) and a cyclic polysiloxane group represented by the following general formula (2) are also suitable as the oxysilyl group.

(In the general formula (1), R ^{9 to} R ¹³ are selected from a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an alkylsiloxy group, and an arylsiloxy group. And p is an integer of 1 to 10.)

(In the general formula (2), R ^{14 to} R ¹⁸ are selected from a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an alkylsiloxy group and an arylsiloxy group. (In addition, q is an integer of 1 to 10.)

In the above general formulas (1) and (2), R ^{9 to} R ¹³ and R ^{14 to} R ¹⁸ are each hydrogen because the polymerization activity in obtaining the cycloolefin ring-opening copolymer is higher. An atom or an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group and a cyclohexyl group is preferable.

The terminal functional group may be introduced only at one polymer chain end (one end) or at both polymer chain ends (both ends), or may be a mixture thereof. Good.

Weight average molecular weight (Mw) of modified cycloolefin ring-opening copolymer, ratio (Mw/Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn), cis/trans ratio, glass transition temperature (Tg), The melting point (Tm) and Mooney viscosity (ML ₁₊₄ , 100° C.) are not particularly limited, but preferred ranges are the same as those for the above cycloolefin ring-opening copolymer.

In the cycloolefin ring-opening copolymer, the introduction ratio of the terminal functional group to the polymer chain terminal is not particularly limited, but from the viewpoint of improving the affinity between the cycloolefin ring-opening copolymer and the filler, ( The ratio of the number of modified cycloolefin ring-opening copolymer chain terminals having terminal functional groups introduced/total number of cycloolefin ring-opening copolymer chain terminals is preferably 10% or more, more preferably 20%. The above is more preferably 30% or more, and particularly preferably 40% or more. In the cycloolefin ring-opening copolymer, the introduction rate of the terminal functional group to the polymer chain terminal can be measured by ¹ H-NMR spectrum. Specifically, the integral value of the peak derived from the proton of the carbon-carbon double bond present in the main chain of the cycloolefin ring-opening copolymer, and the integral value of the peak derived from the terminal functional group, and the number average molecular weight. It can be determined by comparing (Mn).

The method for synthesizing the modified cycloolefin ring-opening copolymer is not particularly limited as long as the desired modified cycloolefin ring-opening copolymer can be obtained, and may be synthesized according to a conventional method. An example of a method for synthesizing a modified cycloolefin ring-opening copolymer that can be suitably used from the viewpoint of obtaining a rubber composition capable of giving a rubber cross-linked product exhibiting excellent properties with low heat buildup will be described below. The method for synthesizing a cycloolefin ring-opening copolymer having no terminal functional group does not use the terminal functional group-containing compound (C), or instead of the terminal functional group-containing compound (C), a molecular weight modifier is used. The method of synthesizing the modified cycloolefin ring-opening copolymer is the same as the method of synthesizing the modified cycloolefin ring-opening copolymer except that an olefin compound or a diolefin compound described later is used.

The modified cycloolefin ring-opening copolymer has a polymerization catalyst containing a Group 6 transition metal compound (A) of the periodic table and an organoaluminum compound (B) represented by the following general formula (3), and a terminal functional group. And a compound (C) having one olefinic carbon-carbon double bond having metathesis reactivity (hereinafter, may be simply referred to as “terminal functional group-containing compound (C)”). , Cyclopentene and cyclooctadiene are subjected to ring-opening copolymerization.
(R ¹ ) _3-a ― _b Al(OR ² ) _a X _b (3)
(In the general formula (3), R ¹ represents a hydrocarbon group having 1 to 20 carbon atoms, R ² represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a halogen atom, X represents a halogen atom, a is 1 or 2, b is 0 or 1, and a+b<3 is satisfied.)
If the terminal functional group-containing compound (C) is not used, a cycloolefin ring-opening copolymer having no terminal functional group can be obtained.

Periodic Table Group 6 transition metal compound (A)
The group 6 transition metal compound (A) of the periodic table is a compound having a group 6 transition metal atom of the periodic table (long period type periodic table, hereinafter the same), specifically, a chromium atom, a molybdenum atom, or a tungsten atom. From the viewpoint of high polymerization activity, a compound having a molybdenum atom or a compound having a tungsten atom is preferable. The Group 6 transition metal compound (A) of the periodic table acts as a polymerization catalyst together with the organoaluminum compound (B) described later. The Group 6 transition metal compound (A) of the Periodic Table is not particularly limited as long as it is a compound having a Group 6 transition metal atom of the Periodic Table, and includes halides, alcoholates, and arylates of Group 6 transition metal atoms of the Periodic Table. Among these, halogenated compounds, oxidized compounds, and imidized compounds are preferable from the viewpoint of high polymerization activity.

Specific examples of the Group 6 transition metal compound (A) of the periodic table include molybdenum pentachloride, molybdenum oxotetrachloride, molybdenum (phenylimide) tetrachloride, tridodecyl ammonium molybdate, methyltrioctyl ammonium molybdate, Molybdenum compounds such as tridecyl ammonium molybdate, trioctyl ammonium molybdate, and tetraphenyl ammonium molybdate; tungsten hexachloride, tungsten oxo tetrachloride, tungsten (phenylimido) tetrachloride, monocatecholate tungsten tetrachloride, bis(3, 5-ditertiarybutyl)catecholate tungsten dichloride, bis(2-chloroetherate)tetrachloride, tungsten compounds such as tungsten oxotetraphenolate; and the like.

The amount of the group 6 transition metal compound (A) used in the periodic table is usually 1:100 to 1:200 in a molar ratio of “group 6 transition metal atom in polymerization catalyst:(cyclopentene+cyclooctadiene)”. 000, preferably 1:200 to 1:150,000, and more preferably 1:500 to 1:100,000. If the amount of the Group 6 transition metal compound (A) used in the periodic table is too small, the polymerization reaction may not proceed sufficiently. On the other hand, if the amount is too large, it may be difficult to remove the catalyst residue from the resulting modified cycloolefin ring-opening copolymer.

Organoaluminum compound (B)
The organoaluminum compound (B) is a compound represented by the following general formula (3). The organoaluminum compound (B) acts as a polymerization catalyst together with the above-mentioned Group 6 transition metal compound (A) of the periodic table.
(R ¹ ) _3-a ― _b Al(OR ² ) _a X _b (3)

In the general formula (3), R ¹ is a hydrocarbon group having 1 to 20 carbon atoms, preferably a hydrocarbon group having 1 to 10 carbon atoms. Specific examples of R ¹ include methyl group, ethyl group, isopropyl group, n-propyl group, isobutyl group, n-butyl group, t-butyl group, n-hexyl group, cyclohexyl group, n-octyl group, n- Alkyl groups such as decyl groups; phenyl groups, 4-methylphenyl groups, 2,6-dimethylphenyl groups, 2,6-diisopropylphenyl groups, aryl groups such as naphthyl groups, and the like.

In the above general formula (3), R ² is a hydrocarbon group having 1 to 20 carbon atoms that may contain a halogen atom, and from the viewpoint of catalytic activity, the number of carbon atoms that may contain a halogen atom. Hydrocarbon groups of 1 to 10 are preferred. Examples of the halogen atom include a fluorine atom, chlorine atom, bromine atom, iodine atom, and the like, and examples of the hydrocarbon group having 1 to 20 carbon atoms include those similar to those exemplified for R ¹ .

As the alkyl group having 1 to 10 carbon atoms containing a halogen atom, 1,3-dichloro-2-propyl group, 1,3-dibromo-2-propyl group, 1-chloro-2-butyl group, 2,2 , 2-trichloroethyl group, 2,2,2-tribromoethyl group, 2,2,2-trifluoroethyl group, 2-trichloromethyl-2-propyl group, tribromomethyl-1-ethyl group, 1, Examples include 1,1,3,3,3-hexafluoro-2-propyl group and the like.

Further, X is a halogen atom, and examples thereof are the same as those exemplified for R ² .

In the above general formula (3), a is 1 or 2, and preferably 1. b is 0 or 1, and satisfies a+b<3. When a mixture of compounds having different values of a and b is to be represented by a chemical formula, a and b may be decimals instead of integers.

The following compounds may be mentioned as specific examples of the organoaluminum compound (B).
Examples of a=1 or 2 and b=0 include diethyl aluminum ethoxide, diethyl aluminum isopropoxide, diisobutyl aluminum butoxide, diisobutyl aluminum mono(n-hexoxide), diethyl aluminum (2-trichloroethoxide), diethyl aluminum. (2-tribromoethoxide), diethyl aluminum (1,3-dichloro-2-propoxide), diethyl aluminum (1,1,1,3,3,3-hexafluoro-2-propoxide), diethyl aluminum (1,1,1-trichloro-2-methyl-2-propoxide), diethyl aluminum (2,6-diisopropylphenoxide), ethyl aluminum di(2-trichloroethoxide), ethyl aluminum di(2-tribromoethoxy) ), ethylaluminium di(1,3-dichloro-2-propoxide), ethylaluminum di(1,1,1,3,3,3-hexafluoro-2-propoxide), ethylaluminum di(1,3). 1,1-trichloro-2-methyl-2-propoxide), ethyl aluminum bis(2,6-diisopropylphenoxide) and the like.

Examples of a=1 and b=1 include ethyl(chloro)aluminum ethoxide, ethyl(chloro)aluminum isopropoxide, ethyl(chloro)aluminum butoxide, ethyl(chloro)aluminum (2-trichloroethoxide), ethyl. (Chloro) aluminum (2-tribromoethoxide), ethyl (bromo) aluminum (1,3-dichloro-2-propoxide), ethyl (chloro) aluminum (1,1,1,3,3,3-hexa) Fluoro-2-propoxide), ethyl(chloro)aluminum (1,1,1-trichloro-2-methyl-2-propoxide), ethyl(chloro)aluminum (2,6-diisopropylphenoxide) and the like.

Such an organoaluminum compound (B) represented by the above general formula (3) is synthesized by a reaction of a trialkylaluminum or alkylaluminum halide with an alcohol, for example, as shown in the following general formula (4). be able to.
(R ¹ ) ₃ ― _b AlX _b + aR ² OH
→ (R ¹ ) _3-a ― _b Al(OR ² ) _a X _b + aR ¹ H (4)
In the general formula (3), a and b are arbitrarily controlled by defining the reaction ratio between the corresponding trialkylaluminum or alkylaluminum halide and the alcohol, as shown in the general formula (4). It is possible.

The amount of the organoaluminum compound (B) used varies depending on the type of the organoaluminum compound (B) used, but is based on the Group 6 transition metal atom of the Periodic Table Group 6 transition metal compound (A). The molar ratio is preferably 0.1 to 100 times, more preferably 0.2 to 50 times, and still more preferably 0.5 to 20 times. If the amount of the organoaluminum compound (B) used is too small, the polymerization activity may be insufficient, and if it is too large, side reactions tend to occur during ring-opening polymerization.

Terminal functional group-containing compound (C)
A compound having a terminal functional group and having one metathesis-reactive olefinic carbon-carbon double bond (terminal functional group-containing compound (C)) is present in the polymerization reaction system of the ring-opening polymerization reaction. And a terminal functional group can be introduced at the polymer chain end of the cycloolefin ring-opening copolymer.
For example, when it is desired to introduce an oxysilyl group at the polymer chain end of the cycloolefin ring-opening copolymer, an oxysilyl group-containing olefinically unsaturated hydrocarbon may be present in the polymerization reaction system.

The oxysilyl group-containing olefinically unsaturated hydrocarbon is a compound having an oxysilyl group and having one olefinic carbon-carbon double bond having metathesis reactivity. By using the oxysilyl group-containing olefinically unsaturated hydrocarbon, an oxysilyl group can be introduced at the polymer chain terminal of the cycloolefin ring-opening copolymer.
Examples of such an oxysilyl group-containing olefinically unsaturated hydrocarbon include compounds represented by the following general formulas (5) to (8).

（上記一般式（５）中、Ｒ¹⁹〜Ｒ²¹は、水素原子、または炭素数１〜１０の炭化水素基であり、Ｒ²²〜Ｒ²⁶は、水素原子、炭素数１〜１０のアルキル基、アリール基、アルコキシ基、アリーロキシ基、アシロキシ基、アルキルシロキシ基、アリールシロキシ基から選択される基である。また、Ｌ¹は、単結合またはオキシシリル基とオレフィン性炭素−炭素二重結合を形成している炭素原子とを結ぶ基であり、ｒは、０〜１０の整数である。但し、ｒ＝０のとき、Ｒ²⁴〜Ｒ²⁶のうち、少なくとも１つは、アルコキシ基、アリーロキシ基、アシロキシ基、アルキルシロキシ基、およびアリールシロキシ基から選択される基である。）

(In said general formula (5), R< ¹⁹ >-R< ²¹ > is a hydrogen atom or a C1-C10 hydrocarbon group, R< ²² >-R< ²⁶ > is a hydrogen atom, a C1-C10 alkyl group. , An aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an alkylsiloxy group, an arylsiloxy group, and L ¹ forms a single bond or an oxysilyl group with an olefinic carbon-carbon double bond. And r is an integer of 0 to 10. However, when r=0, at least one of R ^{24 to} R ²⁶ is an alkoxy group, an aryloxy group, (A group selected from an acyloxy group, an alkylsiloxy group, and an arylsiloxy group.)

（上記一般式（６）中、Ｒ²⁷〜Ｒ²⁹は、水素原子、または炭素数１〜１０の炭化水素基であり、Ｒ³⁰〜Ｒ³⁴は、水素原子、炭素数１〜１０のアルキル基、アリール基、アルコキシ基、アリーロキシ基、アシロキシ基、アルキルシロキシ基、アリールシロキシ基から選択される基である。また、Ｌ²は、単結合またはオキシシリル基とオレフィン性炭素−炭素二重結合を形成している炭素原子とを結ぶ基であり、ｓは、１〜１０の整数である。）

(In the general formula (6), R ^{27 to} R ²⁹ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and R ^{30 to} R ³⁴ are a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. , An aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an alkylsiloxy group, and an arylsiloxy group, and L ² forms a single bond or an oxysilyl group with an olefinic carbon-carbon double bond. Is a group connecting to the carbon atom, and s is an integer of 1 to 10.)

（上記一般式（７）中、Ｒ⁴⁰、Ｒ⁴¹は、水素原子、または炭素数１〜１０の炭化水素基であり、Ｒ³⁵〜Ｒ³⁹、Ｒ⁴²〜Ｒ⁴⁶は、水素原子、炭素数１〜１０のアルキル基、アリール基、アルコキシ基、アリーロキシ基、アシロキシ基、アルキルシロキシ基、アリールシロキシ基から選択される基である。また、Ｌ³、Ｌ⁴は、単結合またはオキシシリル基とオレフィン性炭素−炭素二重結合を形成している炭素原子とを結ぶ基であり、ｔ、ｕは、０〜１０の整数である。但し、ｔ＝０のとき、Ｒ³⁵〜Ｒ³⁷のうち、少なくとも１つは、アルコキシ基、アリーロキシ基、アシロキシ基、アルキルシロキシ基、およびアリールシロキシ基から選択される基であり、ｕ＝０のとき、Ｒ⁴⁴〜Ｒ⁴⁶のうち、少なくとも１つは、アルコキシ基、アリーロキシ基、アシロキシ基、アルキルシロキシ基、およびアリールシロキシ基から選択される基である。）

(In the general formula (7), R ⁴⁰ and R ⁴¹ are hydrogen atoms or a hydrocarbon group having 1 to 10 carbon atoms, and R ^{35 to} R ³⁹ and R ^{42 to} R ⁴⁶ are hydrogen atoms and carbon atoms. 1 to 10 is a group selected from an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an alkylsiloxy group and an arylsiloxy group, and L ³ and L ⁴ are a single bond or an oxysilyl group and an olefin. gender carbon -. a group linking the carbon atoms forming the carbon-carbon double bond, t, u is an integer of 0, however, when t = 0, of R ³⁵ to R ^37, At least one is a group selected from an alkoxy group, an aryloxy group, an acyloxy group, an alkylsiloxy group, and an arylsiloxy group, and when u=0, at least one of R ^{44 to} R ⁴⁶ is an alkoxy group. Group, an aryloxy group, an acyloxy group, an alkylsiloxy group, and an arylsiloxy group.)

（上記一般式（８）中、Ｒ⁵²、Ｒ⁵³は、水素原子、または炭素数１〜１０の炭化水素基であり、Ｒ⁴⁷〜Ｒ⁵¹、Ｒ⁵⁴〜Ｒ⁵⁸は、水素原子、炭素数１〜１０のアルキル基、アリール基、アルコキシ基、アリーロキシ基、アシロキシ基、アルキルシロキシ基、アリールシロキシ基から選択される基である。また、Ｌ⁵、Ｌ⁶は、単結合またはオキシシリル基とオレフィン性炭素−炭素二重結合を形成している炭素原子とを結ぶ基であり、ｖ、ｗは、１〜１０の整数である。）

(In the general formula (8), R ⁵² and R ⁵³ are a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and R ^{47 to} R ⁵¹ and R ^{54 to} R ⁵⁸ are a hydrogen atom and a carbon number. 1 to 10 is a group selected from an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, an alkylsiloxy group and an arylsiloxy group, and L ⁵ and L ⁶ are a single bond or an oxysilyl group and an olefin. Is a group connecting to a carbon atom forming a carbon-carbon double bond, and v and w are integers of 1 to 10.)

In formulas (5) to (8), R ^{19 to} R ²¹ , R ^{27 to} R ²⁹ , R ⁴⁰ , R ⁴¹ , R ⁵² , and R ⁵³ are preferably hydrogen atoms, and these are hydrogen atoms. Thereby, the oxysilyl group-containing olefinically unsaturated hydrocarbon can be made more excellent in the metathesis reactivity.

In the general formulas (5) to (8), L ^{1 to} L ⁶ are not particularly limited as long as they are groups capable of binding an oxysilyl group and a carbon atom forming an olefinic carbon-carbon double bond. However, from the viewpoint that the oxysilyl group-containing olefinically unsaturated hydrocarbon can be made more excellent in metathesis reactivity, a hydrocarbon group, an ether group, or a tertiary amino group is preferable, and a hydrocarbon group having 1 to 20 carbon atoms is used. An aliphatic hydrocarbon group and an aromatic hydrocarbon group having 6 to 20 carbon atoms are more preferable. Further, the oxysilyl group and the carbon atom forming the olefinic carbon-carbon double bond may be directly bonded to each other without passing through these groups.

In addition, when the compounds represented by the general formulas (5) and (6) are used among the compounds represented by the above general formulas (5) to (8), they undergo a metathesis reaction to generate a cycloolefin. An oxysilyl group can be introduced into at least one terminal of the ring copolymer, and when the compounds represented by the general formulas (7) and (8) are used, they undergo a metathesis reaction to give a cycloolefin. An oxysilyl group can be introduced at both ends of the ring-opening copolymer.

Preferred specific examples of the compounds represented by the general formulas (5) and (6) include vinyl(trimethoxy)silane, vinyl(triethoxy)silane, allyl(trimethoxy)silane, allyl(methoxy)(dimethyl)silane and allyl(triethoxy). ) Silane, allyl(ethoxy)(dimethyl)silane, styryl(trimethoxy)silane, styryl(triethoxy)silane, styrylethyl(triethoxy)silane, allyl(triethoxysilylmethyl)ether, allyl(triethoxysilylmethyl)(ethyl) Alkoxysilane compounds such as amines; vinyl(triphenoxy)silane, allyl(triphenoxy)silane, allyl(phenoxy)(dimethyl)silane and other aryloxysilane compounds; vinyl(triacetoxy)silane, allyl(triacetoxy)silane, Acyloxysilane compounds such as allyl(diacetoxy)methylsilane and allyl(acetoxy)(dimethyl)silane; alkylsiloxysilane compounds such as allyltris(trimethylsiloxy)silane; arylsiloxysilane compounds such as allyltris(triphenylsiloxy)silane; 1- Polysiloxane compounds such as allylheptamethyltrisiloxane, 1-allylnonamethyltetrasiloxane, 1-allylnonamethylcyclopentasiloxane, 1-allylundecamethylcyclohexasiloxane; and the like.

Specific preferred examples of the compounds represented by the general formulas (7) and (8) include 1,4-bis(trimethoxysilyl)-2-butene, 1,4-bis(triethoxysilyl)-2-butene, Alkoxysilane compounds such as 1,4-bis(trimethoxysilylmethoxy)-2-butene; aryloxysilane compounds such as 1,4-bis(triphenoxysilyl)-2-butene; 1,4-bis(triacetoxy) Silyl)-2-butene and other acyloxysilane compounds; 1,4-bis[tris(trimethylsiloxy)silyl]-2-butene and other alkylsiloxysilane compounds; 1,4-bis[tris(triphenylsiloxy)silyl ] Arylsiloxysilane compounds such as 2-butene; Polysiloxane compounds such as 1,4-bis(heptamethyltrisiloxy)-2-butene and 1,4-bis(undecamethylcyclohexasiloxy)-2-butene ; And the like.

The amount of the terminal functional group-containing compound (C) such as an oxysilyl group-containing olefinically unsaturated hydrocarbon used may be appropriately selected according to the molecular weight of the modified cycloolefin ring-opening copolymer to be produced. The terminal functional group-containing compound (C) is used in a molar ratio of usually 1/100 to 1/100,000, preferably 1/200 to 1/50, with respect to the total amount of cyclopentene and cyclooctadiene. 000, more preferably 1/500 to 1/10,000. The terminal functional group-containing compound (C) acts as a molecular weight modifier in addition to the function of introducing a functional group into the polymer chain terminal of the cycloolefin ring-opening copolymer. If the amount of the terminal functional group-containing compound (C) used is too small, the production rate of the modified cycloolefin ring-opening copolymer may be low, and if it is too large, the molecular weight of the resulting modified cycloolefin ring-opening copolymer may be low. It may become low.

Further, in order to adjust the molecular weight of the cycloolefin ring-opening copolymer having no terminal functional group, as a molecular weight regulator, 1-butene, 1-pentene, 1-hexene, olefin compounds such as 1-octene and 1, Using diolefin compounds such as 4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,6-heptadiene, 2-methyl-1,4-pentadiene, 2,5-dimethyl-1,5-hexadiene It may be added to the polymerization reaction system. The amount of the molecular weight modifier used can be appropriately selected from the same range as the amount of the terminal functional group-containing compound (C) used.

Further, in the present invention, an oxygen atom-containing hydrocarbon compound may be further used as a polymerization catalyst. By further using the oxygen atom-containing hydrocarbon compound, the polymerization activity can be improved and the weight average molecular weight of the obtained cycloolefin ring-opening copolymer can be improved. The oxygen atom-containing hydrocarbon compound is not particularly limited as long as it is a hydrocarbon compound having an oxygen atom, and is an ester compound, a ketone compound or an ether having 2 to 30 carbon atoms which may have a halogen atom as a substituent. A compound is preferable, and an ester compound, a ketone compound, or an ether compound having 4 to 10 carbon atoms is preferable from the viewpoints of the effect of improving the polymerization activity at room temperature or higher and the effect of increasing the molecular weight. The ester compound, ketone compound or ether compound may be a cyclic ester compound, a ketone compound or an ether compound, and more than one ester bond, a ketone bond or an ether compound in one molecule. It may be a compound containing a bond.

Specific examples of the ester compound include ethyl acetate, butyl acetate, amyl acetate, octyl acetate, 2-chloroethyl acetate, methyl acetyl acrylate, ε-caprolactone, dimethyl glutarate, σ-hexanolactone and diacetoxyethane. Be done.

Specific examples of the ketone compound include acetone, ethylmethylketone, acetylacetone, acetophenone, cyclohexylphenylketone, 1'-acetonaphthone, methyl 2-acetylbenzoate, 4'-chloroacetophenone, chloroacetone, 1,3-dichloro-2. -Examples include propanone.

Specific examples of the ether compound include diethyl ether, tetrahydrofuran, 1,2-dimethoxyethane, ethylene glycol diethyl ether, 1,4-dioxane and the like.

When the oxygen atom-containing hydrocarbon compound is used, the amount used varies depending on the kind of the oxygen atom-containing hydrocarbon compound used, but is a Group 6 transition metal compound (A) of the Periodic Table Group 6 It is preferably 0.1 to 10 times mol, more preferably 0.2 to 8 times mol, and further preferably 0.5 to 5 times mol, of the transition metal atom. If the amount of the oxygen atom-containing hydrocarbon compound used is too small, the effect of adding the oxygen atom-containing hydrocarbon compound tends to be difficult to obtain, and if it is too large, the polymerization activity may be insufficient.

In the method for producing a ring-opening copolymer modified cycloolefin ring-opening copolymer, the above-mentioned periodic table group 6 transition metal compound (A) and organoaluminum compound (B), and an oxygen atom-containing compound added if necessary Using a polymerization catalyst containing a hydrocarbon compound, cyclopentene/cyclooctadiene ring-opening copolymerization is carried out by bringing them into contact with cyclopentene and cyclooctadiene in the presence of the terminal functional group-containing compound (C).

The method for bringing them into contact with each other to initiate ring-opening polymerization is not particularly limited.
For example, in the presence of cyclopentene, cyclooctadiene, a terminal functional group-containing compound (C), an organoaluminum compound (B), and optionally an oxygen atom-containing hydrocarbon compound, a Group 6 transition metal compound of the periodic table ( A method of initiating the ring-opening copolymerization of cyclopentene/cyclooctadiene by adding A) can be mentioned. Alternatively, a Group 6 transition metal compound (A) of the Periodic Table, an organoaluminum compound (B) and, if necessary, an oxygen atom-containing hydrocarbon compound are mixed in advance, and cyclopentene, cyclooctadiene and a terminal functional group are contained therein. Ring-opening polymerization of cyclopentene/cyclooctadiene may be carried out by adding the compound (C).

Further, the terminal functional group-containing compound (C) may be mixed in advance with cyclopentene and cyclooctadiene, or may be mixed with cyclopentene/cyclooctadiene during ring-opening copolymerization. .. In addition, after the ring-opening copolymerization of cyclopentene/cyclooctadiene, the terminal functional group-containing compound (C) is added to the obtained ring-opening copolymer, and the obtained ring-opening copolymer and metathesis are added. You may make it react.

In the method for producing a modified cycloolefin ring-opening copolymer, the ring-opening copolymerization reaction may be carried out without solvent or in a solvent. As a solvent used when performing the ring-opening copolymerization reaction in a solvent, cyclopentene, cyclooctadiene used for ring-opening copolymerization, other copolymerizable cyclic olefin compound, which is inert in the ring-opening copolymerization, the periodic table Any solvent that can dissolve the Group 6 transition metal compound (A), the organoaluminum compound (B), and the terminal functional group-containing compound (C) may be used. Although such a solvent is not particularly limited, for example, a hydrocarbon solvent is preferably used. Specific examples of the hydrocarbon solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; aliphatic hydrocarbons such as n-hexane, n-heptane, and n-octane; cyclohexane, cyclopentane, and methyl. Alicyclic hydrocarbons such as cyclohexane; and the like.

The polymerization temperature is not particularly limited, but is preferably −100° C. or higher, more preferably −50° C. or higher, further preferably −20° C. or higher, particularly preferably 0° C. or higher. Although the upper limit of the polymerization temperature is not particularly limited, it is preferably lower than 100°C, more preferably lower than 90°C, further preferably lower than 80°C, and particularly preferably lower than 70°C. If the polymerization temperature is too high, the molecular weight of the resulting modified cycloolefin ring-opening copolymer may be too low.If the polymerization temperature is too low, the polymerization rate will be slow, and as a result, the productivity may be poor. ..

The polymerization reaction time is not particularly limited, but is preferably 1 minute to 72 hours, more preferably 10 minutes to 20 hours.

In the method for producing a modified cycloolefin ring-opening copolymer, a Group 6 transition metal compound (A), an organoaluminum compound (B) and a terminal functional group-containing compound (C), and cyclopentene and cyclooctadiene are used in the periodic table. Initiating ring-opening polymerization by contacting, and after the polymerization conversion rate reaches a predetermined value, by adding a known polymerization terminator to the polymerization system to stop it, a modified cycloolefin ring-opening copolymer is produced. You can

Further, in the present invention, an antioxidant such as a phenol-based stabilizer, a phosphorus-based stabilizer and a sulfur-based stabilizer may be added to the obtained ring-opening copolymer, if desired. The amount of the antioxidant added may be appropriately determined depending on the type of the antioxidant. Further, in the present invention, an extender oil may be blended, if desired.

Furthermore, when carrying out the polymerization reaction, a solvent is used, and when the polymerization reaction is carried out in the solvent, as a method for obtaining the copolymer from the polymer solution, a known method may be adopted and is not particularly limited. However, for example, a method of separating the solvent by steam stripping, filtering the solid, and then drying the solid to obtain a solid rubber can be adopted.

From the viewpoint of improving the rubber properties and processability of the rubber composition, and from the viewpoint of obtaining a rubber composition that is a rubber crosslinked product excellent in low heat buildup, the cycloolefin ring-opening copolymer is a modified cycloolefin opening copolymer. The ring copolymer is preferably contained in an amount of 10 to 100% by weight, more preferably 20 to 100% by weight.

(Styrene-butadiene copolymer)
The styrene-butadiene copolymer contains a structural unit derived from styrene and a structural unit derived from butadiene. The structural unit derived from styrene refers to a structural unit formed by polymerizing styrene. Further, the structural unit derived from butadiene refers to a structural unit formed by polymerizing butadiene.

From the viewpoint of improving the low heat buildup of the obtained rubber cross-linked product and ensuring wet grip properties, the content of structural units derived from styrene in the styrene-butadiene copolymer is preferably in all monomer units, It is 5 to 50% by weight, more preferably 10 to 45% by weight, and the content of the butadiene-derived structural unit is preferably 50 to 95% by weight, more preferably 55 to 90% by weight.

Examples of butadiene include 1,2-butadiene and 1,3-butadiene, and 1,3-butadiene is preferable.

Further, the styrene-butadiene copolymer in the present invention may contain a structural unit derived from another monomer that is copolymerizable, in addition to the structural unit derived from styrene and the structural unit derived from butadiene. . Such other copolymerizable monomers include 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, Conjugated dienes other than butadiene such as 2-chloro-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, and 2,4-hexadiene; 1,5-hexadiene, 1,6-heptadiene, 1, Non-conjugated dienes such as 7-octadiene, dicyclopentadiene and 5-ethylidene-2-norbornene; α,β-unsaturated nitrile compounds such as (meth)acrylonitrile, α-chloroacrylonitrile and α-ethylacrylonitrile; (meth)acrylic acid Unsaturated carboxylic acids such as itaconic acid and fumaric acid; chlorostyrene, vinyltoluene, t-butylstyrene, vinylbenzoic acid, methyl vinylbenzoate, vinylnaphthalene, chloromethylstyrene, hydroxymethylstyrene, α-methylstyrene, divinyl. Aromatic vinyl monomers other than styrene such as benzene; olefins such as ethylene and propylene; halogen atom-containing monomers such as vinyl chloride and vinylidene chloride; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, etc. Vinyl esters; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and butyl vinyl ether; vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, butyl vinyl ketone, hexyl vinyl ketone and isopropenyl vinyl ketone; N-vinylpyrrolidone, vinyl pyridine, Heterocycle-containing vinyl compounds such as vinylimidazole; (meth)acrylic acid ester compounds such as methyl (meth)acrylate; hydroxyalkyl group-containing compounds such as β-hydroxyethyl (meth)acrylate; (meth)acrylamide, N-methylol Examples thereof include amide monomers such as (meth)acrylamide and acrylamido-2-methylpropanesulfonic acid. The above-mentioned other copolymerizable monomers may be used alone or in combination of two or more kinds at an arbitrary ratio. Further, in the present specification, (meth)acrylic includes both acrylic and methacrylic. In the styrene-butadiene copolymer of the present invention, the content of structural units derived from other copolymerizable monomers is preferably 45% by weight or less, more preferably 35% by weight or less.

The weight average molecular weight (Mw) of the styrene-butadiene copolymer, the ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), and the Mooney viscosity (ML ₁₊₄ , 100° C.) are particularly limited. However, the preferred range is the same as that of the modified styrene-butadiene copolymer described later.

As a method for producing the styrene-butadiene copolymer, for example, a solution polymerization method, a suspension polymerization method, a bulk polymerization method, an emulsion polymerization method or the like can be used. As the polymerization reaction, any of radical polymerization, anionic polymerization, cationic polymerization, coordination anionic polymerization, coordination cationic polymerization, living polymerization and the like may be used. Examples of living polymerization include living anionic polymerization, living cationic polymerization, and living radical polymerization. Among these, from the viewpoint of obtaining the modified styrene-butadiene copolymer described below, it is preferable to obtain the styrene-butadiene copolymer by the solution polymerization method. Styrene-butadiene copolymer obtained by the solution polymerization method, since it is possible to introduce a modifying group at the polymer chain end, when a filler such as silica or carbon black is blended in the rubber composition, Excellent due to the affinity between the modifying group and the filler. As a result, the dispersibility of the filler in the rubber composition is improved. On the other hand, when a styrene-butadiene polymer is produced by an emulsion polymerization method, a modifying group cannot be introduced at the polymer chain terminal.

Modified styrene-butadiene copolymer The styrene-butadiene copolymer in the present invention is a styrene-butadiene copolymer having a modifying group at the polymer chain terminal (hereinafter referred to as "modified styrene-butadiene copolymer". Is included). The modified styrene-butadiene copolymer is obtained by reacting a styrene-butadiene copolymer chain having an active terminal with a modifier having a reactive group capable of reacting with the active terminal. When a filler such as silica or carbon black is added to the rubber composition according to the present invention by introducing a modifying group into the polymer chain end of the styrene-butadiene copolymer, the compatibility with the filler is improved. Property is further improved and the dispersibility of the filler is excellent. As a result, it is possible to obtain a rubber composition which is a crosslinked rubber excellent in low heat buildup and wet grip properties.

The method for synthesizing the modified styrene-butadiene copolymer is not particularly limited as long as the desired modified styrene-butadiene copolymer can be obtained, and may be synthesized by a conventional method. An example of a method for synthesizing a modified styrene-butadiene copolymer that can be preferably used will be described below from the viewpoint of obtaining a rubber composition capable of giving a rubber crosslinked product having excellent low heat buildup and excellent wet grip properties. The method for synthesizing the styrene-butadiene copolymer having no terminal modifying group is the same as the method for synthesizing the modified styrene-butadiene copolymer except that no modifier is used.

In the method for synthesizing a modified styrene-butadiene copolymer, a styrene-butadiene copolymer chain having an active end that reacts with a modifier is used in the presence of an inert solvent, such as styrene, butadiene, and other copolymerizable monomers. It is obtained by polymerizing a monomer with a polymerization initiator.

The inert solvent used in the polymerization is not particularly limited as long as it is one that is usually used in solution polymerization and does not inhibit the polymerization reaction. Specific examples thereof include chain aliphatic hydrocarbons such as butane, pentane, hexane, and 2-butene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and cyclohexene; aromatic carbonization such as benzene, toluene, and xylene. Hydrogen; and the like. The amount of the inert solvent used is such that the monomer concentration is usually 1 to 50% by weight, preferably 10 to 40% by weight.

The polymerization initiator used in the polymerization is not particularly limited as long as it can polymerize each of the above monomers to give a styrene-butadiene copolymer chain having an active terminal. As specific examples thereof, a polymerization initiator having an organic alkali metal compound, an organic alkaline earth metal compound, a lanthanum series metal compound or the like as a main catalyst is preferably used. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium and stilbenelithium; dilithiomethane, 1,4-dilithiobutane, 1,4. -Organic polyvalent lithium compounds such as dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, and 1,3,5-tris(lithiomethyl)benzene; Organic sodium compounds such as sodium naphthalene; Organic compounds such as potassium naphthalene Potassium compounds; and the like. Examples of the organic alkaline earth metal compound include di-n-butylmagnesium, di-n-hexylmagnesium, diethoxycalcium, calcium distearate, di-t-butoxystrontium, diethoxybarium and diisopropoxybarium. , Diethyl mercapto barium, di-t-butoxy barium, diphenoxy barium, diethyl amino barium, barium distearate, diketyl barium and the like. Examples of the polymerization initiator having a lanthanum-based metal compound as a main catalyst include, for example, lanthanum-based metals such as lanthanum, cerium, praseodymium, neodymium, samarium, and gadolinium, and carboxylic acids, and lanthanide-based metals including phosphorus-containing organic acids. And the like, and a polymerization initiator comprising a salt thereof as a main catalyst and a cocatalyst such as an alkylaluminum compound, an organic aluminum hydride compound, and an organic aluminum halide compound. Among these polymerization initiators, organic monolithium compounds and organic polyvalent lithium compounds are preferable, organic monolithium compounds are more preferable, and n-butyllithium is particularly preferable. The organic alkali metal compound is used as an organic alkali metal amide compound by previously reacting with a secondary amine such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, hexamethyleneimine, and heptamethyleneimine. Good. These polymerization initiators may be used alone or in combination of two or more.

The amount of the polymerization initiator used may be determined according to the desired molecular weight, but is usually in the range of 1 to 50 mmol, preferably 2 to 20 mmol, and more preferably 4 to 15 mmol per 1000 g of the monomer.

The polymerization temperature is usually in the range of -80 to +150°C, preferably 0 to 100°C, more preferably 30 to 90°C. As the polymerization mode, any mode such as a batch system and a continuous system can be adopted, but the batch system is preferable because it is easy to control the randomness of the bond between the structural unit derived from styrene and the structural unit derived from butadiene.

The bonding mode of each structural unit constituting the styrene-butadiene copolymer chain having an active terminal can be various bonding modes such as block, taper, and random, but is random. Preferably. The rubber cross-linked product obtained by making it random has excellent low heat buildup.

In order to adjust the vinyl bond content in the butadiene-derived structural unit in the styrene-butadiene copolymer chain having an active terminal, it is preferable to add a polar compound to the inert solvent during the polymerization. Examples of the polar compound include ether compounds such as dibutyl ether and tetrahydrofuran; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; phosphine compounds. Among these, ether compounds and tertiary amines are preferable, tertiary amines are more preferable, and tetramethylethylenediamine is particularly preferable. These polar compounds may be used alone or in combination of two or more. The amount of the polar compound used may be determined according to the intended vinyl bond content, and is usually 0.001 to 10 mol, preferably 0.005 to 8 mol, and more preferably 0, relative to 1 mol of the polymerization initiator. It is in the range of 0.01 to 5 mol. When the amount of the polar compound used is in the above range, the vinyl bond content in the structural unit derived from butadiene can be easily adjusted, and a problem due to deactivation of the polymerization initiator hardly occurs.

The content of vinyl bond in the structural unit derived from butadiene in the styrene-butadiene copolymer chain having an active terminal is preferably 0 to 80% by weight, more preferably 5 to 70% by weight, and particularly preferably It is 10 to 65% by weight. When the content of the vinyl bond is within the above range, the obtained rubber cross-linked product is excellent in low heat buildup.

The peak top molecular weight of the styrene-butadiene copolymer chain having an active terminal detected by gel permeation chromatography (GPC) is 100,000 to 1,000,000 in terms of polystyrene. Is more preferable, 150,000 to 850,000 is more preferable, and 200,000 to 700,000 is particularly preferable. When multiple peaks of the styrene-butadiene copolymer chain are observed, the peak top molecular weight of the peak with the smallest molecular weight derived from the styrene-butadiene copolymer chain detected by gel permeation chromatography is determined. , The peak top molecular weight of a styrene-butadiene copolymer chain having an active terminal. When the peak top molecular weight of the styrene-butadiene copolymer chain having an active terminal is within the above range, the obtained rubber cross-linked product will be excellent in low heat buildup.

The molecular weight distribution represented by the ratio (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the styrene-butadiene copolymer chain having an active terminal is preferably 1.0 to 1.5, It is more preferably 1.0 to 1.4, and particularly preferably 1.0 to 1.3. When the value (Mw/Mn) of this molecular weight distribution is in the above range, the obtained rubber cross-linked product is excellent in low heat buildup.

The modifier has, in one molecule, a reactive group capable of reacting with the active end of the styrene-butadiene copolymer chain, and a modifying group contained in the polymer chain end of the styrene-butadiene copolymer after the reaction. It is characterized by

The reactive group capable of reacting with the active terminal of the styrene-butadiene copolymer chain is not particularly limited as long as it can react with the active terminal, but from the viewpoint of reactivity with the active terminal, a halogen atom, 2 -Pyrrolidonyl group, vinyl group, alkoxy group, amino group or epoxy group is preferable, 2-pyrrolidonyl group, epoxy group or alkoxy group is more preferable, and epoxy group is particularly preferable.

Examples of the modifying group contained at the polymer chain end of the styrene-butadiene copolymer after the reaction with the active end of the styrene-butadiene copolymer chain include an amino group, a hydroxyl group, and a group containing a silicon atom. Examples of the group containing a silicon atom include those exemplified as the "functional group containing a silicon atom" in the modified cycloolefin ring-opening copolymer.

（上記一般式（９）中、Ｒ¹〜Ｒ⁸は、それぞれ独立して、炭素数１〜６のアルキル基、または炭素数６〜１２のアリール基である。Ｘ¹およびＸ⁴は、それぞれ独立して、スチレンーブタジエン共重合体鎖の活性末端と反応可能な反応基、炭素数１〜６のアルキル基、または炭素数６〜１２のアリール基である。Ｘ²は、スチレンーブタジエン共重合体鎖の活性末端と反応可能な反応基であり、複数あるＸ²は互いに同一であっても相違していてもよい。Ｘ³は、２〜２０のアルキレングリコールの繰返し単位を含有する基であり、Ｘ³が複数あるときは、それらは互いに同一であっても相違していてもよい。ｍは３〜２００の整数、ｎは０〜２００の整数、ｋは０〜２００の整数である。）The modifier used in the present invention has a reactive group capable of reacting with the active end of the styrene-butadiene copolymer chain and a modifying group contained at the polymer chain end of the styrene-butadiene copolymer after the reaction. If so, the polyorganosiloxane and the silicon compound such as the hydrocarbyloxysilane compound are preferable from the viewpoint of affinity with the filler such as silica and carbon black, although not particularly limited thereto. The polyorganosiloxane is not particularly limited as long as it has a reactive group capable of reacting with the active end of the styrene-butadiene copolymer chain, and specific examples thereof include the polyorganosiloxane represented by the following general formula (9). Examples thereof include siloxane. Further, the hydrocarbyloxysilane compound is not particularly limited as long as it has a reactive group capable of reacting with the active end of the styrene-butadiene copolymer chain, but a specific example thereof is shown by the following general formula (10). Hydrocarbyloxysilane compounds; tetraalkoxysilane compounds such as tetramethoxysilane and tetraethoxysilane; hexaalkoxysilane compounds such as bis(trimethoxysilyl)ethane and bis(trimethoxysilyl)hexane; alkylalkoxy such as methyltriethoxysilane Silane compounds; vinylalkoxysilane compounds such as vinyltrimethoxysilane; arylalkoxysilane compounds such as phenyltrimethoxysilane; halogenoalkoxysilane compounds such as triethoxychlorosilane; 3-glycidoxyethyltrimethoxysilane, 3-glycidoxy Epoxy group-containing alkoxysilane compounds such as butylpropyltrimethoxysilane and bis(3-glycidoxypropyl)dimethoxysilane; sulfur-containing alkoxysilane compounds such as bis(3-(triethoxysilyl)propyl)disulfide; bis(3- Amino group-containing alkoxysilane compounds such as trimethoxysilylpropyl)methylamine; isocyanate group-containing alkoxysilane compounds such as tris(3-trimethoxysilylpropyl)isocyanurate; and the like. Other examples of the silicon compound used in the present invention include tetrahalogenated silane compounds such as tetrachlorosilane. Among these, the polyorganosiloxane represented by the following general formula (9) and the hydrocarbyloxysilane compound represented by the following general formula (10) are more preferable. In particular, the rubber cross-linked product obtained by using the polyorganosiloxane represented by the following general formula (9) is excellent in low heat buildup.

(In the general formula (9), R ^{1 to} R ⁸ are each independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms. X ¹ and X ⁴ are respectively Independently, it is a reactive group capable of reacting with the active end of the styrene-butadiene copolymer chain, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and X ² is styrene-butadiene copolymer. It is a reactive group capable of reacting with the active end of the polymer chain, and a plurality of X ² may be the same or different from each other X ³ is a group containing 2 to 20 repeating units of alkylene glycol. And when X ³ is plural, they may be the same or different from each other, m is an integer of 3 to 200, n is an integer of 0 to 200, and k is an integer of 0 to 200. is there.)

（上記一般式（１０）中、Ｒ⁹は、炭素数１〜１２のアルキレン基であり、Ｒ⁹が複数あるときは、それらは互いに同一であっても相違していてもよい。Ｒ¹⁰〜Ｒ¹⁸は、それぞれ独立して、炭素数１〜６のアルキル基、または炭素数６〜１２のアリール基である。ｒは１〜１０の整数である。）

In (the general formula (10), R ⁹ is an alkylene group having 1 to 12 carbon atoms, when R ⁹ there are multiple, they mutually identical a good .R ¹⁰ be different even ~ Each R ¹⁸ is independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and r is an integer of 1 to 10.)

In the polyorganosiloxane represented by the general formula (9), examples of the alkyl group having 1 to 6 carbon atoms that constitutes R ^{1 to} R ⁸ , X ¹ , and X ⁴ include a methyl group, an ethyl group, and n-. Examples thereof include a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a methylphenyl group. Among these, a methyl group and an ethyl group are preferable from the viewpoint of easy production of the polyorganosiloxane itself.

In the polyorganosiloxane represented by the general formula (9), the reactive group capable of reacting with the active terminal of the styrene-butadiene copolymer chain forming X ¹ , X ² , and X ⁴ has 1 to 5 carbon atoms. The alkoxy group, the hydrocarbon group containing a 2-pyrrolidonyl group, and the epoxy group-containing group having 4 to 12 carbon atoms are preferable, and the epoxy group-containing group having 4 to 12 carbon atoms is more preferable.

Examples of the alkoxy group having 1 to 5 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group. Among these, a methoxy group and an ethoxy group are preferable from the viewpoint of reactivity with the active end of the styrene-butadiene copolymer chain.

Examples of the hydrocarbon group containing a 2-pyrrolidonyl group include those represented by the following general formula (11).

（上記一般式（１１）中、ｊは２〜１０の整数であり、２であることが好ましい。）

(In the general formula (11), j is an integer of 2 to 10, and is preferably 2.)

Examples of the C4-12 group containing an epoxy group include those represented by the following general formula (12).
-Z ¹ -Z ² -E (12)
(In the general formula (12), Z ¹ is an alkylene group or an alkylarylene group having 1 to 10 carbon atoms, Z ² is a methylene group, a sulfur atom, or an oxygen atom, and E is a carbon atom having an epoxy group. It is a hydrocarbon group of the number 2 to 10. Among these, those in which Z ² is an oxygen atom are preferable, those in which Z ² is an oxygen atom and E is a glycidyl group are more preferable, and Z ¹ is It is particularly preferable that it is an alkylene group having 3 carbon atoms, Z ² is an oxygen atom, and E is a glycidyl group.)

In the polyorganosiloxane represented by the general formula (9), R ^{1 to} R ⁸ are preferably an alkyl group having 1 to 6 carbon atoms among the above, and X ¹ and X ⁴ are the above. Among them, an alkyl group having 1 to 6 carbon atoms is preferable, and among the above, X ² is preferably an epoxy group-containing group having 4 to 12 carbon atoms.

（上記一般式（１３）中、ｔは２〜２０の整数であり、Ｔは炭素数２〜１０のアルキレン基またはアルキルアリーレン基であり、Ｒは、水素原子またはメチル基であり、複数あるＲは互いに同一であっても相違していてもよい。Ｑは炭素数１〜１０のアルコキシ基またはアリーロキシ基である。これらの中でも、ｔが２〜８の整数であり、Ｔが炭素数３のアルキレン基であり、Ｒが水素原子であり、かつＱがメトキシ基であるものが好ましい。）In the polyorganosiloxane represented by the general formula (9), examples of the group containing a repeating unit of X ³ , that is, an alkylene glycol of 2 to 20, include those represented by the following general formula (13). ..

(In the general formula (13), t is an integer of 2 to 20, T is an alkylene group having 2 to 10 carbon atoms or an alkylarylene group, R is a hydrogen atom or a methyl group, and there are a plurality of Rs. May be the same as or different from each other, Q is an alkoxy group or an aryloxy group having 1 to 10 carbon atoms, and among these, t is an integer of 2 to 8 and T is 3 carbon atoms. Preferred is an alkylene group, R is a hydrogen atom, and Q is a methoxy group.)

In the polyorganosiloxane represented by the general formula (9), m is an integer of 3 to 200, preferably 3 to 150, and more preferably 3 to 120. When the number of m is within the above range, the obtained rubber cross-linked product is excellent in low heat buildup.

In the polyorganosiloxane represented by the general formula (9), n is an integer of 0 to 200, preferably 0 to 150, more preferably 0 to 120. k is an integer of 0 to 200, preferably 0 to 150, more preferably 0 to 120. The total number of m, n, and k is preferably 3 to 400, more preferably 3 to 300, and particularly preferably 3 to 250. When the total number of m, n, and k is too large, the viscosity of the polymerization solution during the reaction becomes too high, which may make it difficult to produce the modified styrene-butadiene copolymer.

In the polyorganosiloxane represented by the general formula (9), when the epoxy group in the polyorganosiloxane reacts with the active end of the styrene-butadiene copolymer chain, at least a part of the epoxy groups in the polyorganosiloxane is It is considered that the ring-opening forms a bond between the carbon atom in the ring-opened portion of the epoxy group and the styrene-butadiene copolymer chain. In addition, when the alkoxy group in the polyorganosiloxane reacts with the active terminal of the styrene-butadiene copolymer, at least a part of the alkoxy group in the polyorganosiloxane is released, resulting in a silicon atom contained in the polyorganosiloxane. It is believed that a bond is formed between the styrene and the styrene-butadiene copolymer chain. When the 2-pyrrolidonyl group in the polyorganosiloxane reacts with the active terminal of the styrene-butadiene copolymer, the carbon-oxygen bond of the carbonyl group constituting at least a part of the 2-pyrrolidonyl group in the polyorganosiloxane is It is believed that the bond is cleaved to form a bond between the carbon atom and the styrene-butadiene copolymer chain.

In the hydrocarbyloxysilane compound represented by the general formula (10), the alkyl group having 1 to 6 carbon atoms and the aryl group having 6 to 12 carbon atoms are the same as those described for the polyorganosiloxane of the general formula (9). It is the same.

In the hydrocarbyloxysilane compound represented by the general formula (10), examples of the alkylene group having 1 to 12 carbon atoms include methylene group, ethylene group, and propylene group. Of these, a propylene group is preferable.

Specific examples of the hydrocarbyloxysilane compound represented by the general formula (10) include N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane and N,N-bis(trimethylsilyl)-3-aminopropyltrisilane. Examples thereof include ethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane.

The amount of the modifier such as a silicon compound used is 0.01 to 10 mol based on 1 mol of the polymerization initiator used for the polymerization reaction, and the molar amount of the reactive group capable of reacting with the active end of the styrene-butadiene copolymer chain. The amount is preferably 0.05 to 8 mol, more preferably 0.05 to 8 mol, and particularly preferably 0.1 to 4 mol. When the amount of the modifier used is in the above range, the obtained rubber cross-linked product is excellent in low heat buildup. These modifiers can be used alone or in combination of two or more kinds.

The styrene-butadiene copolymer preferably contains the modified styrene-butadiene copolymer in an amount of 1 to 100% by weight, more preferably 10 to 100% by weight, and particularly preferably 50 to 100% by weight. When the content of the modified styrene-butadiene copolymer in the styrene-butadiene copolymer is within the above range, the rubber composition is excellent in processability, and the obtained rubber crosslinked product is excellent in low heat buildup. Becomes

In addition to the modified styrene-butadiene copolymer, the styrene-butadiene copolymer is obtained by polymerizing a part of the active end of the styrene-butadiene copolymer chain with a coupling agent within a range that does not impair the effects of the present invention. It may contain a coupled styrene-butadiene copolymer which is coupled by being added to the system.

Examples of the coupling agent used at this time include tin tetrachloride; hexachlorodisilane, bis(trichlorosilyl)methane, 1,2-bis(trichlorosilyl)ethane, 1,3-bis(trichlorosilyl)propane, 1, 4-bis(trichlorosilyl)butane, 1,5-bis(trichlorosilyl)pentane, and a silicon halide compound such as 1,6-bis(trichlorosilyl)hexane; and the like. By using a coupling agent together, a high molecular weight coupled styrene-butadiene copolymer can be produced. These coupling agents may be used alone or in combination of two or more.

As a method of reacting a styrene-butadiene copolymer chain having an active terminal with a modifying agent or a coupling agent, a solution containing a styrene-butadiene copolymer chain having an active terminal, a modifying agent or a coupling agent is used. If and can be mixed, it will not be specifically limited. From the viewpoint of satisfactorily controlling the modification reaction and the coupling reaction, a method of adding the modifier or the coupling agent to the solution containing the styrene-butadiene copolymer chain having an active terminal is preferable. At that time, it is more preferable that the modifier and the coupling agent are dissolved in an inert solvent and added to the polymerization system. The solution concentration is preferably in the range of 1 to 50% by weight.

The timing of adding the modifier etc. to the solution containing the styrene-butadiene copolymer chain having an active terminal is not particularly limited, but the polymerization reaction is not completed and the styrene-butadiene copolymer chain having an active terminal is present. The solution containing the monomer also contains a monomer, more specifically, the solution containing the styrene-butadiene copolymer chain having an active terminal is 100 ppm or more, more preferably 300 to 50,000 ppm. It is desirable to add a denaturing agent or the like to this solution while containing the monomer (1). By adding a modifier or the like in this manner, side reactions between the styrene-butadiene copolymer chain having an active terminal and impurities contained in the polymerization system can be suppressed, and the reaction can be well controlled. It will be possible.

The reaction temperature of the styrene-butadiene copolymer chain having an active terminal is usually in the range of 0 to 100° C., preferably 30 to 90° C., and the reaction is carried out under the conditions. The time is usually in the range of 1 minute to 120 minutes, preferably 2 minutes to 60 minutes.

The order of adding both the modifier and the coupling agent to the solution containing the styrene-butadiene copolymer chain having an active terminal is not particularly limited. Either one of them may be added first, or both may be added at the same time, but it is preferable to add the coupling agent before the modifier. By carrying out in such an order, it becomes possible to surely form the coupled styrene-butadiene copolymer.

After reacting the above-mentioned modifier and optionally a coupling agent to the active end of the styrene-butadiene copolymer chain, a polymerization terminator such as alcohol or water such as methanol or isopropanol or water is added. It is preferable to deactivate unreacted active ends.

After deactivating the active terminals of the styrene-butadiene copolymer chain, if desired, anti-aging agents such as phenol-based stabilizers, phosphorus-based stabilizers, sulfur-based stabilizers, crumbing agents, and scale inhibitors may be added. Add to polymerization solution. Then, the modified styrene-butadiene copolymer is recovered by separating the polymerization solvent from the polymerization solution by direct drying or steam stripping. Before the polymerization solvent is separated from the polymerization solution, an extension oil may be mixed with the polymerization solution to recover the modified styrene-butadiene copolymer as an oil-extended rubber.

Examples of the extender oil used when the modified styrene-butadiene copolymer is recovered as an oil-extended rubber include paraffinic, aromatic and naphthenic petroleum softeners, plant softeners, and fatty acids. .. When using a petroleum-based softening agent, the content of polycyclic aromatics extracted by the method of IP346 (inspection method of THE INSTITUTE PETROLEUM in the UK) is preferably less than 3%. When the extender oil is used, its amount is usually 5 to 100 parts by weight, preferably 10 to 60 parts by weight, and more preferably 20 to 50 parts by weight, based on 100 parts by weight of the modified styrene-butadiene copolymer. Is.

The weight average molecular weight of the modified styrene-butadiene copolymer is preferably 100,000 to 3,000,000, more preferably 150,000 to 2,500,000, as a value measured by gel permeation chromatography in terms of polystyrene. 200,000 to 2,000,000 are particularly preferable. When the weight average molecular weight of the modified styrene-butadiene copolymer is within the above range, it becomes easy to mix silica into the modified styrene-butadiene copolymer, and the processability of the rubber composition is excellent. As a result, the rubber cross-linked product obtained is excellent in low heat buildup.

The molecular weight distribution represented by the ratio (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the modified styrene-butadiene copolymer is preferably 1.1 to 3.0. It is more preferably 0.2 to 2.5, and particularly preferably 1.2 to 2.2. When the value (Mw/Mn) of the molecular weight distribution of the modified styrene-butadiene copolymer is within the above range, the obtained rubber cross-linked product has excellent low heat buildup.

The modified styrene-butadiene copolymer has a Mooney viscosity (ML ₁₊₄ , 100° C.) of preferably 20 to 100, more preferably 30 to 90, and particularly preferably 35 to 80. When the modified styrene-butadiene copolymer is used as an oil-extended rubber, it is preferable that the Mooney viscosity of the oil-extended rubber be within the above range.

The weight ratio of the cycloolefin ring-opening copolymer and the styrene-butadiene copolymer in the rubber composition according to the present invention is "cycloolefin ring-opening copolymer/styrene-butadiene copolymer" and is 5/95-. It is 95/5. The weight of the cycloolefin ring-opening copolymer and the styrene-butadiene copolymer from the viewpoint of improving the processability of the rubber composition and from the viewpoint of obtaining a rubber composition that is a rubber crosslinked product having excellent low heat buildup. The ratio is preferably 5/95 to 85/15, more preferably 15/85 to 55/45.

In the method for producing the rubber composition according to the present invention, the method of kneading the cycloolefin ring-opening copolymer and the styrene-butadiene copolymer is not particularly limited, and each component may be kneaded according to a conventional method. .. The kneading temperature of the cycloolefin ring-opening copolymer and the styrene-butadiene copolymer is preferably 80 to 200°C, more preferably 120°C to 180°C. The kneading time is preferably 30 seconds to 30 minutes.

As described above, the rubber composition according to the present invention contains the rubber component containing the cycloolefin ring-opening copolymer and the styrene-butadiene copolymer in a predetermined weight ratio.

The rubber composition according to the present invention contains, as a rubber component, a rubber other than a cycloolefin ring-opening copolymer or a styrene-butadiene copolymer (hereinafter sometimes referred to as "other rubber"). You may stay. Examples of other rubbers include natural rubber, polyisoprene rubber, and polybutadiene rubber (high cis-BR, low cis-BR. Also, polybutadiene rubber containing crystal fibers made of 1,2-polybutadiene polymer may be used. ), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, acrylonitrile-butadiene copolymer rubber and the like. Among these, natural rubber, polyisoprene rubber, and polybutadiene rubber are preferable. The above-mentioned other rubbers can be used alone or in combination of two or more kinds.

In the rubber composition according to the present invention, the total amount of the cycloolefin ring-opening copolymer and the styrene-butadiene copolymer is preferably 50 to 100% by weight, and preferably 60 to 100% by weight in the rubber component. Is more preferable, and it is particularly preferable to occupy 70 to 100% by weight. By setting the ratio of the total amount of the cycloolefin ring-opening copolymer and the styrene-butadiene copolymer in the rubber component to the above range, the processability of the rubber composition is improved. Further, a rubber cross-linked product excellent in low heat buildup can be obtained from the rubber composition.

The rubber composition according to the present invention preferably further comprises silica and/or carbon black.

(silica)
The rubber composition according to the present invention preferably contains silica as a filler. Silica interacts with the terminal functional group of the modified cycloolefin ring-opening copolymer and the modifying group of the modified styrene-butadiene copolymer, and as a result, the dispersibility of silica in the rubber composition is further improved. To do.

Specific examples of silica include dry method white carbon, wet method white carbon, colloidal silica, and precipitated silica. Alternatively, a carbon-silica dual phase filler in which silica is supported on the surface of carbon black may be used. Among these, wet method white carbon containing hydrous silicic acid as a main component is preferable. These can be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of silica is preferably 50 to 300 m ² /g, more preferably 80 to 250 m ² /g, and further preferably 100 to 220 m ² /g. Silica having a nitrogen adsorption specific surface area in the above range may aggregate in the rubber composition, but in the present invention, by using a modified cycloolefin ring-opening copolymer or a modified styrene-butadiene copolymer, It is possible to obtain a rubber composition which has a further improved affinity, is suppressed in agglomeration of silica, and is a rubber crosslinked product excellent in low heat buildup. Since the heat generation is low, the obtained tire is expected to improve fuel efficiency. If the nitrogen adsorption specific surface area of silica is less than 50 m ² /g, the mechanical properties of the rubber cross-linked product may deteriorate. When the nitrogen adsorption specific surface area of silica exceeds 300 m ² /g, the cohesive force of silica becomes large, and it may be difficult to suppress coagulation. Further, the pH of silica is preferably less than 7, more preferably 5 to 6.9. The nitrogen adsorption specific surface area can be measured by the BET method according to ASTM D3037-81.

The content of silica is preferably 1 to 150 parts by weight, more preferably 10 to 120 parts by weight, further preferably 15 to 100 parts by weight, and particularly preferably 20 to 100 parts by weight of the rubber component in the rubber composition. 80 parts by weight. By setting the content of silica in the above range, it is possible to obtain a rubber composition which is a rubber cross-linked product excellent in low heat buildup.

(Carbon black)
Further, the rubber composition according to the present invention may contain carbon black as a filler. Examples of carbon black include furnace black, acetylene black, thermal black, channel black, graphite and the like. Among these, it is preferable to use furnace black, and specific examples thereof include SAF, ISAF, ISAF-HS, ISAF-LS, IISAF-HS, HAF, HAF-HS, HAF-LS, T-HS, and T. -NS, MAF, FEF etc. are mentioned. These can be used alone or in combination of two or more.

The nitrogen adsorption specific surface area of carbon black is preferably 5 to 200 m ² /g, more preferably 20 to 130 m ² /g, and further preferably 40 to 80 m ² /g. Further, the adsorption amount of dibutyl phthalate (DBP) of carbon black as a filler is preferably 5 to 200 ml/100 g, more preferably 50 to 160 ml/100 g, and further preferably 70 to 130 ml/100 g. When the specific surface area of carbon black and the amount of adsorbed dibutyl phthalate are within the above ranges, it is possible to obtain a rubber composition which is a rubber crosslinked product having good moldability and excellent low heat buildup.

When carbon black is used as the filler, the compounding amount is preferably 1 to 150 parts by weight, more preferably 2 to 120 parts by weight, and further preferably 3 to 100 parts by weight of the rubber component in the rubber composition. 100 parts by weight, particularly preferably 5 to 80 parts by weight. By setting the blending amount of carbon black within the above range, it is possible to obtain a rubber composition which is a crosslinked rubber excellent in low heat buildup.

Moreover, when both the silica and the carbon black are blended in the rubber composition according to the present invention, the total amount of the silica and the carbon black is 100 parts by weight of the total amount of the rubber components in the rubber composition. , Preferably 25 to 200 parts by weight, more preferably 30 to 150 parts by weight.

(Silane coupling agent)
When silica is blended as the filler, it is preferable to further blend a silane coupling agent from the viewpoint of obtaining a rubber composition which is a rubber cross-linked product having further improved low heat buildup. Examples of the silane coupling agent include β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-octanoylthio-1-propyl-trisilane. Ethoxysilane, bis(3-(triethoxysilyl)propyl)disulfide, bis(3-(triethoxysilyl)propyl)tetrasulfide, γ-trimethoxysilylpropyldimethylthiocarbamyltetrasulfide, γ-trimethoxysilylpropylbenzo Examples thereof include thiazyl tetrasulfide. Among these, from the viewpoint of avoiding scorch during kneading, one containing 4 or less sulfur in one molecule is preferable. These silane coupling agents can be used alone or in combination of two or more kinds. The blending amount of the silane coupling agent is preferably 0.1 to 30 parts by weight, and more preferably 1 to 15 parts by weight with respect to 100 parts by weight of silica.

The method of adding a filler such as silica or carbon black to the rubber component is not particularly limited, and a method of adding to a solid rubber and kneading (dry kneading method) and a method of adding to a rubber solution and coagulating/drying (Wet kneading method) or the like can be applied.

In addition to the above-mentioned components, the rubber composition according to the present invention has a crosslinking agent, a crosslinking accelerator, a crosslinking activator, a process oil, an activator, a filler (excluding silica and carbon black), and an adhesive according to a conventional method. A necessary amount of compounding agents such as an imparting agent, an antiaging agent, an anti-scorch agent, a plasticizer, a lubricant, aluminum hydroxide and wax can be added.

Examples of the cross-linking agent include sulfur, sulfur-containing compounds such as sulfur halides, organic peroxides, quinone dioximes, organic polyvalent amine compounds, and methylphenol group-containing alkylphenol resins. Among these, sulfur is preferably used. The content of the cross-linking agent is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, based on 100 parts by weight of the rubber component in the rubber composition. Is. When the compounding amount of the crosslinking agent is within the above range, crosslinking is sufficiently performed, and the obtained rubber crosslinked product has excellent mechanical properties.

When sulfur or a sulfur-containing compound is used as the crosslinking agent, it is preferable to use a crosslinking accelerator and a crosslinking activator together.

Examples of the crosslinking accelerator include N-cyclohexyl-2-benzothiazolyl sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazolyl sulfenamide, Sulfenamide compounds such as N-oxyethylene-2-benzothiazolyl sulfenamide and N,N'-diisopropyl-2-benzothiazolyl sulfenamide; 1,3-diphenylguanidine, dioltotolylguanidine, ortho Examples thereof include guanidine compounds such as tolylbiguanidine; thiourea compounds; thiazole compounds; thiuram compounds; dithiocarbamic acid compounds; xanthogenic acid compounds. Among these, those containing a sulfenamide compound are preferable. These crosslinking accelerators may be used alone or in combination of two or more. The compounding amount of the crosslinking accelerator is not particularly limited, but is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 10 parts by weight, particularly preferably 100 parts by weight of the rubber component in the rubber composition. Is 1 to 5 parts by weight.

Examples of the cross-linking activator include zinc oxide; higher fatty acids such as stearic acid; and the like. These crosslinking activators may be used alone or in combination of two or more. The compounding amount of the cross-linking activator is not particularly limited, but is preferably 0.05 to 20 parts by weight, more preferably 0.5 to 15 parts by weight with respect to 100 parts by weight of the rubber component in the rubber composition. .. When the compounding amounts of the crosslinking accelerator and the crosslinking activator are in the above ranges, the crosslinking is sufficiently performed, and the obtained rubber crosslinked product has excellent mechanical properties.

Examples of process oils include paraffin-based, aromatic-based, and naphthene-based petroleum-based softeners; plant-based softeners; fatty acids; and the like.

In order to obtain the rubber composition according to the present invention, each component may be kneaded according to a conventional method. For example, the compounding agent excluding the cross-linking agent and the cross-linking accelerator and the rubber component are kneaded, and then the cross-linking agent and the cross-linking accelerator are mixed with the kneaded product to obtain the desired rubber composition. The kneading temperature of the compounding agent excluding the crosslinking agent and the crosslinking accelerator and the rubber component is preferably 80 to 200°C, more preferably 120 to 180°C. The kneading time is preferably 30 seconds to 30 minutes. The kneaded product is mixed with the crosslinking agent and the crosslinking accelerator after cooling to 100° C. or lower, preferably 80° C. or lower.

The rubber composition thus obtained can be used for a tire by crosslinking, for example.

(2) Crosslinked rubber The crosslinked rubber according to the present invention is obtained by crosslinking the rubber composition according to the present invention containing a crosslinking agent. The method for crosslinking and molding the rubber composition according to the present invention is not particularly limited, and may be selected according to the shape, size, etc. of the rubber crosslinked material. The mold may be filled with a rubber composition containing a cross-linking agent and heated to cross-link simultaneously with molding. After the rubber composition containing a cross-linking agent is molded in advance, it is heated to cross-link. You may. The temperature at the time of molding is preferably 20 to 140°C, more preferably 40 to 130°C. The crosslinking temperature is preferably 120 to 200°C, more preferably 140 to 180°C, and the crosslinking time is usually 1 to 120 minutes.

The rubber cross-linked product according to the present invention is used for rubber products such as tires, hoses, window frames, belts, shoe soles, anti-vibration rubbers, automobile parts, and seismic isolation rubbers. Among these, the rubber cross-linked product according to the present invention is particularly excellent in low heat build-up, and thus is suitably used for tire applications. The rubber cross-linked product according to the present invention can be used in various tires such as all-season tires, high-performance tires, and studless tires, and various tire parts such as treads, carcasses, sidewalls, and bead parts. However, since it is particularly excellent in low heat buildup, it is particularly preferably used for a tread of a fuel-efficient tire.

Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples. In the following, "part" is based on weight unless otherwise specified. The tests and evaluations were as follows.

[Molecular weight]
The number average molecular weight (Mn), the weight average molecular weight (Mw), and the molecular weight distribution (Mw/Mn) of the polymer were measured as polystyrene conversion values by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.

[Introduction Rate of Oxysilyl Group in Polymer]
^{By 1} H-NMR spectrum measurement, the ratio of the peak integrated value derived from the oxysilyl group and the peak integrated value derived from the carbon-carbon double bond in the polymer main chain was determined, and the ratio of this peak integrated value and GPC were determined. Based on the measured value of the number average molecular weight (Mn), the introduction ratio of oxysilyl groups [(percentage of the number of polymer chain terminals introduced with oxysilyl groups/the total number of polymer chain terminals]] was calculated.

[Cis/trans ratio]
The cis/trans ratio of the polymer was determined from ¹³ C-NMR spectrum measurement.

[Copolymerization ratio]
The amount of residual monomer in the polymerization system was measured using gas chromatography using Inert Cap1 (manufactured by GL Sciences Inc.) as a capillary column, and the copolymerization ratio of the cycloolefin ring-opening copolymer was calculated from the residual amount. ..

[Polymer melting point (Tm), glass transition temperature (Tg) and transition enthalpy (ΔH)]
The melting point (Tm), glass transition temperature (Tg) and transition enthalpy (ΔH) of the polymer were measured using a differential scanning calorimeter (DSC) at a temperature increase of 10° C./min. The melting point (Tm) and the enthalpy of transition (ΔH) of the cycloolefin ring-opening copolymers of Production Examples 1 and 2 could not be measured.
The melting point (Tm), glass transition temperature (Tg) and transition enthalpy (ΔH) are
Each is a value that is a measure of crystallinity. When the crystallinity of the cycloolefin ring-opening copolymer is low (amorphous), the melting point (Tm) cannot be measured. Even when the melting point (Tm) can be measured, the closer the transition enthalpy (ΔH) is to 0, the lower the crystallinity. The lower the crystallinity of the cycloolefin ring-opening copolymer, the more excellent the processability of the rubber composition obtained using the cycloolefin ring-opening copolymer, and the rubber crosslinked product obtained by crosslinking the rubber composition. Can be said to have excellent low heat buildup.

[Processability of rubber composition]
The Mooney viscosity (ML ₁₊₄ , 100° C.) of the rubber composition was measured according to JIS K6300 using a Mooney viscometer (manufactured by Shimadzu Corporation). This value was used as an index with the measured value of the sample of Comparative Example 1 as 100. It can be said that the smaller the index, the better the workability.

[Evaluation of low heat build-up of rubber composition]
The sample rubber composition was press-crosslinked at 160° C. for 20 minutes to prepare a crosslinked test piece. For this test piece, tan δ at 60° C. was measured using a viscoelasticity measuring device (trade name “ARES-G2”, manufactured by TA Instruments Co., Ltd.) under the conditions of shear strain of 2% and frequency of 10 Hz. This value was used as an index with the measured value of the sample of Comparative Example 1 as 100. The smaller this index, the better the low heat buildup.

[Reference Example 1]
Preparation of diisobutylaluminum mono(n-hexoxide)/toluene solution (2.5% by weight) 88 parts of toluene and 25.4% by weight of triisobutylaluminum/n in a glass container containing a stir bar under a nitrogen atmosphere. 7.8 parts of hexane solution (manufactured by Tosoh Finechem Co., Ltd.) was added. Then, the container was cooled to −45° C., and 1.02 parts (equivalent amount relative to triisobutylaluminum) of n-hexanol was slowly added dropwise with vigorous stirring. Then, the mixture was left to stand at room temperature with stirring to prepare a diisobutylaluminum mono(n-hexoxide)/toluene solution (2.5% by weight).

[Production Example 1: Production of cycloolefin ring-opening copolymer]
87 parts of a 1.0 wt% WCl ₆ /toluene solution and 2.5 wt% of diisobutylaluminum mono(n-hexoxide)/toluene prepared in Reference Example 1 were placed in a glass container containing a stir bar under a nitrogen atmosphere. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. Then, under a nitrogen atmosphere, in a pressure-resistant glass reaction vessel equipped with a stirrer, 270 parts of cyclopentene, 48 parts of 1,5-cyclooctadiene, 300 parts of toluene and 1.09 part of 1,4-bis(triethoxysilyl)-2-butene. Then, 130 parts of the catalyst solution prepared above was added thereto, and a polymerization reaction was carried out at 25° C. for 4 hours. After the polymerization reaction for 4 hours, excess ethyl alcohol was added to the pressure-resistant glass reaction container to stop the polymerization, and then the solution in the pressure-resistant glass reaction container was treated with 2,6-di-t-butyl-p-cresol (BHT). ) Containing a large excess of ethyl alcohol. Next, the precipitated polymer was recovered, washed with ethyl alcohol, and then vacuum dried at 40° C. for 3 days to open 61 parts of a polymer chain with a both-end modified cycloolefin having triethoxysilyl groups at both ends. Ring copolymer 1 was obtained.

Then, for the obtained both-end modified cycloolefin ring-opening copolymer 1, according to the above method, molecular weight, cis/trans ratio, oxysilyl group introduction rate, copolymerization ratio, melting point (Tm), glass transition temperature (Tg), And the enthalpy of transition (ΔH) were measured. The results are shown in Table 1.

[Production Example 2: Production of cycloolefin ring-opening copolymer]
The compounding amounts of cyclopentene, 1,5-cyclooctadiene and 1,4-bis(triethoxysilyl)-2-butene were changed. Specifically, the same procedure as in Example 1 was repeated except that 210 parts of cyclopentene, 143 parts of 1,5-cyclooctadiene and 0.93 part of 1,4-bis(triethoxysilyl)-2-butene were used. Polymerization was carried out to obtain a cycloolefin ring-opening copolymer 2 modified at both ends with a triethoxysilyl group at both ends of the polymer chain of 76 parts. Then, with respect to the obtained both-end modified cycloolefin ring-opening copolymer 2, each measurement was performed in the same manner as in Production Example 1. The results are shown in Table 1.

[Production Example 3: Production of cyclopentene ring-opening polymer]
87 parts of a 1.0 wt% WCl ₆ /toluene solution and 2.5 wt% of diisobutylaluminum mono(n-hexoxide)/toluene prepared in Reference Example 1 were placed in a glass container containing a stir bar under a nitrogen atmosphere. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. Then, under a nitrogen atmosphere, 300 parts of cyclopentene, 300 parts of toluene and 1.24 parts of 1,4-bis(triethoxysilyl)-2-butene were added to a pressure-resistant glass reaction vessel equipped with a stirrer, and prepared here above. 130 parts of the above catalyst solution was added and a polymerization reaction was carried out at 25° C. for 4 hours. After the polymerization reaction for 4 hours, excess ethyl alcohol was added to the pressure-resistant glass reaction container to stop the polymerization, and then the solution in the pressure-resistant glass reaction container was treated with 2,6-di-t-butyl-p-cresol (BHT). ) Containing a large excess of ethyl alcohol. Then, the precipitated polymer was recovered, washed with ethyl alcohol, and then vacuum dried at 40° C. for 3 days to open a cyclopentene ring-opening group having a triethoxysilyl group at both ends of 63 parts of the polymer chain. Polymer 3 was obtained.

Then, each measurement of the obtained both-end modified cyclopentene ring-opening polymer 3 was carried out in the same manner as in Production Example 1. The results are shown in Table 1.

[Production Example 4: Production of cyclopentene ring-opening polymer]
87 parts of a 1.0 wt% WCl ₆ /toluene solution and 2.5 wt% of diisobutylaluminum mono(n-hexoxide)/toluene prepared in Reference Example 1 were placed in a glass container containing a stir bar under a nitrogen atmosphere. A catalyst solution was obtained by adding 43 parts of the solution and stirring for 15 minutes. Then, under a nitrogen atmosphere, 300 parts of cyclopentene, 300 parts of toluene and 1.55 parts of 1,4-bis(triethoxysilyl)-2-butene were added to a pressure resistant glass reaction vessel equipped with a stirrer, and prepared here as above. 130 parts of the above catalyst solution was added, and a polymerization reaction was performed at 40° C. for 4 hours. After the polymerization reaction for 4 hours, excess ethyl alcohol was added to the pressure-resistant glass reaction container to stop the polymerization, and then the solution in the pressure-resistant glass reaction container was treated with 2,6-di-t-butyl-p-cresol (BHT). ) Containing a large excess of ethyl alcohol. Then, the precipitated polymer was recovered, washed with ethyl alcohol, and then vacuum dried at 40° C. for 3 days to open a cyclopentene ring-opening group having a triethoxysilyl group at both ends of 63 parts of the polymer chain. Polymer 4 was obtained.

Then, with respect to the obtained both-end modified cyclopentene ring-opening polymer 4, each measurement was performed in the same manner as in Production Example 1. The results are shown in Table 1.

[Production Example 5: Production of modified styrene-butadiene copolymer]
In a nitrogen atmosphere, 800 g of cyclohexane, 0.85 mmol of tetramethylethylenediamine, 94.8 g of 1,3-butadiene, and 25.2 g of styrene were charged into an autoclave with a stirrer, and 0.71 mmol of n-butyllithium was added, and the temperature was 60°C. Polymerization was started at. Then, after confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.08 mmol of tin tetrachloride was added and reacted for 30 minutes. Then, a polyorganosiloxane A represented by the following formula (14) was added to a xylene solution having a concentration of 20% by weight so that the content of the epoxy group was 0.33 times the mol of n-butyllithium used. It was added in the state and reacted for 30 minutes. Thereafter, as a polymerization terminator, methanol was added in an amount corresponding to twice the molar amount of the n-butyllithium used to obtain a solution containing the modified styrene-butadiene copolymer. To this solution, 0.15 parts of Irganox 1520L (manufactured by Ciba Specialty Chemicals) as an anti-aging agent was added to 100 parts of the modified styrene-butadiene copolymer, and then the solvent was removed by steam stripping. After vacuum drying at 60° C. for 24 hours, a solid modified styrene-butadiene copolymer was obtained.

The modified styrene-butadiene copolymer obtained had an Mn of 336,000, an Mw of 481,000 and a molecular weight distribution (Mw/Mn) of 1.43 as a whole in GPC measurement. The content of styrene-derived structural units in this modified styrene-butadiene copolymer was 21.2% by weight, and the vinyl bond content in the butadiene-derived structural units was 62.6, as determined by ¹ H-NMR measurement. % By weight.

[Example 1]
In a Brabender type mixer having a capacity of 250 ml, 30 parts of both-end modified cycloolefin ring-opening copolymer 1 obtained in Production Example 1 and 70 parts of modified styrene-butadiene copolymer obtained in Production Example 5 were added for 30 seconds. It was meditated. Next, silica (manufactured by Rhodia, trade name “Zeosil 1115MP”, nitrogen adsorption specific surface area (BET method): 112 m ² /g) 50 parts, process oil (manufactured by Nippon Oil Corporation, trade name “Alomax T-DAE”) 25 Parts and silane coupling agent: 6.0 parts of bis(3-(triethoxysilyl)propyl)tetrasulfide (manufactured by Degussa, trade name “Si69”), and the starting temperature was 110° C. to 1.5. Kneaded for minutes. Then, 25 parts of silica (manufactured by Rhodia, trade name "Zeosil 1115MP"), 3 parts of zinc oxide, 2 parts of stearic acid and an antioxidant: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylene. 2 parts of diamine (manufactured by Ouchi Shinko Co., Ltd., trade name "Nocrac 6C") was added, and the mixture was kneaded for 2.5 minutes, and the kneaded product was discharged from the mixer. The temperature of the kneaded material at the end of kneading was 150°C. After cooling the kneaded material to room temperature, it was kneaded again in the Brabender type mixer at a starting temperature of 110° C. for 3 minutes, and then the kneaded material was discharged from the mixer. Then, with an open roll at 50° C., the obtained kneaded product, 1.4 parts of sulfur and a crosslinking accelerator (N-tert-butyl-2-benzothiazolyl sulfenamide (trade name “Nocceller NS-P” ( Ouchi Shinko Chemical Industry Co., Ltd.)) 1.2 parts and 1,3-diphenylguanidine (trade name "NOXCELLER D" (Ouchi Shinko Chemical Industry Co., Ltd.) 1.2 parts) 2.4 parts) After kneading, a sheet-shaped rubber composition was obtained. The obtained rubber composition was evaluated for workability and low heat build-up according to the above method. The results are shown in Table 2.

[Example 2]
30 parts of both-end modified cycloolefin ring-opening copolymer 2 obtained in Production Example 2 was used instead of 30 parts of both-end modified cycloolefin ring-opening copolymer 1 obtained in Production Example 1. A sheet-shaped rubber composition was obtained in the same manner as in Example 1. The obtained rubber composition was evaluated for workability and low heat build-up according to the above method. The results are shown in Table 2.

[Comparative Example 1]
Example except that 30 parts of both-end modified cyclopentene ring-opening polymer 3 obtained in Production Example 3 was used in place of 30 parts of both-end modified cycloolefin ring-opening copolymer 1 obtained in Production Example 1. A rubber composition in a sheet form was obtained in the same manner as in 1. The obtained rubber composition was evaluated for workability and low heat build-up according to the above method. The results are shown in Table 2.

[Comparative Example 2]
Examples except that 30 parts of both-end modified cycloolefin ring-opening copolymer 1 obtained in Production Example 1 was replaced with 30 parts of both-end modified cyclopentene ring-opening polymer 4 obtained in Production Example 4 A rubber composition in a sheet form was obtained in the same manner as in 1. The obtained rubber composition was evaluated for workability and low heat build-up according to the above method. The results are shown in Table 2.

As is clear from the results shown in Table 2, the rubber composition according to the present invention provided a rubber crosslinked product having excellent processability and low heat buildup (Examples 1 and 2).
On the other hand, in place of the cycloolefin ring-opening copolymer, a rubber composition using a cyclopentene ring-opening polymer, which is a homopolymer of cyclopentene, is inferior in processability to the rubber composition according to the present invention, Further, it gave a rubber cross-linked product having a low heat buildup (Comparative Examples 1 and 2).

Claims (11)

Cyclopentene-derived structural unit, and a cycloolefin ring-opening copolymer containing a structural unit derived from cyclooctadiene, and styrene-butadiene copolymer,
In the cycloolefin ring-opening copolymer, the content of structural units derived from cyclopentene in all repeating units is 50 to 99 mol%, the content of structural units derived from cyclooctadiene is 50 to 1 mol%,
The cycloolefin ring-opened copolymer and the styrene - weight ratio of the butadiene copolymer (cycloolefin ring-opened copolymer / styrene - butadiene copolymer) is Ri 5/95 to 95/5 der,
A rubber composition in which the cis/trans ratio of the double bonds present in the structural units constituting the cycloolefin ring-opening copolymer is in the range of 30/70 to 90/10 . The cycloolefin ring-opening copolymer has a cyclohexyl group having a functional group containing at least one atom selected from the group consisting of a nitrogen atom, an oxygen atom, a phosphorus atom, a sulfur atom, and a silicon atom at the polymer chain terminal. The rubber composition according to claim 1, comprising an olefin ring-opening copolymer. The rubber composition according to claim 2, wherein the cycloolefin ring-opening copolymer contains a cycloolefin ring-opening copolymer having an oxysilyl group at the polymer chain end. The rubber composition according to claim 1, wherein the styrene-butadiene copolymer contains a styrene-butadiene copolymer having a modifying group at a polymer chain end. The rubber composition according to any one of claims 1 to 4, which comprises silica and/or carbon black. The rubber composition according to any one of claims 1 to 5, which comprises a crosslinking agent. A rubber cross-linked product obtained by cross-linking the rubber composition according to claim 6. A tire comprising the rubber cross-linked product according to claim 7. A method for producing the rubber composition according to any one of claims 1 to 6, comprising:
In the presence of a Group 6 transition metal compound (A) of the periodic table and an organoaluminum compound (B) represented by the following general formula (3), cyclopentene and cyclooctadiene are subjected to ring-opening copolymerization to open a cycloolefin. Obtaining a ring copolymer,
A method for producing a rubber composition, which comprises a step of kneading the cycloolefin ring-opening copolymer and a styrene-butadiene copolymer.
(R ¹ ) _3-a − _b Al(OR ² ) _a X _b (3)
(In the general formula (3), R ¹ represents a hydrocarbon group having 1 to 20 carbon atoms, R ² represents a hydrocarbon group having 1 to 20 carbon atoms which may contain a halogen atom, X represents a halogen atom, a is 1 or 2, b is 0 or 1, and a+b<3 is satisfied.) 10. The ring-opening copolymerization of cyclopentene and cyclooctadiene is further carried out in the presence of the oxysilyl group-containing olefinically unsaturated hydrocarbon (C) in the step of obtaining the cycloolefin ring-opening copolymer. Method for producing rubber composition. The method for producing a rubber composition according to claim 9, further comprising a step of obtaining a styrene-butadiene copolymer by a solution polymerization method.