JP7517978B2 - Copolymer, rubber composition, resin composition, tire and resin product - Google Patents

Description

The present invention relates to a copolymer, a rubber composition, a resin composition, a tire, and a resin product.

2. Description of the Related Art Conventionally, various polymers and rubber compositions and resin compositions containing the same have been developed for use in tires and resin products.
For example, the following Patent Document 1 discloses a copolymer of a conjugated diene compound and a non-conjugated olefin, in which the amount of 1,2-vinyl bonds in the conjugated diene compound portion is 10 mol % or more, and more specifically, an ethylene-butadiene copolymer produced by copolymerizing ethylene and butadiene in the presence of a complex having scandium as a central metal. Furthermore, the following Patent Document 1 discloses that a rubber composition containing the ethylene-butadiene copolymer has excellent wet properties and low temperature properties.

JP 2012-131965 A

The above-mentioned tires and resin products are often required to have high durability. In this regard, the inventors have conducted research and found that the copolymer disclosed in the above-mentioned Patent Document 1 does not have sufficient durability and there is room for improvement.

Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional techniques and to provide a polymer having excellent durability.
Another object of the present invention is to provide a rubber composition, a resin composition, a tire, and a resin product which contain such a polymer and have excellent durability.

The polymer of the present invention that solves the above problems is a copolymer containing non-conjugated olefin units and substituted butadiene units, and its essential configuration is as follows:

［式中、Ｒ^１～Ｒ^６は、それぞれ独立して水素原子又は炭素数１～１２の一価の炭化水素基であり、但し、Ｒ^１～Ｒ^６の内、少なくとも１つは、炭素数１～１２の一価の炭化水素基である。］で表される置換ブタジエン化合物に由来することを特徴とする。
かかる本発明の共重合体は、耐久性に優れる。 The copolymer of the present invention is a copolymer containing non-conjugated olefin units and substituted butadiene units,
the amount of vinyl bonds (1,2-vinyl bonds and 3,4-vinyl bonds) in the substituted butadiene units is 20 to 60 mol %,
The main chain is composed only of acyclic structures,
The content of the substituted butadiene unit is 25 mol% or more,
The weight average molecular weight (Mw) is 50,000 or more,
The substituted butadiene units are linked together,
The substituted butadiene unit is represented by the following general formula (1):

[wherein R ¹ to R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, provided that at least one of R ¹ to R ⁶ is a monovalent hydrocarbon group having 1 to 12 carbon atoms.]
Such a copolymer of the present invention has excellent durability.

In a preferred embodiment of the copolymer of the present invention, the content of the non-conjugated olefin units is 5 to 65 mol %. In this case, the durability of the copolymer is further improved, and the workability is also improved.

In another preferred embodiment of the copolymer of the present invention, the non-conjugated olefin units are derived from an α-olefin having 2 to 8 carbon atoms. In this case, the raw materials are easily available and versatile, and the production costs of the copolymer can be reduced.

Here, it is preferable that the non-conjugated olefin units are derived from ethylene or propylene. In this case, the raw materials are more readily available and versatile, and the production costs of the copolymer can be further reduced.

In another preferred embodiment of the copolymer of the present invention, the substituted butadiene compound is selected from at least one of isoprene, myrcene, and farnesene. In this case, it is preferable from the viewpoint of the sustainability of the raw material.

Here, the substituted butadiene compound is preferably isoprene. In this case, when the copolymer is blended with natural rubber, the compatibility between the copolymer and natural rubber is good.

The copolymer of the present invention preferably has a melting point of 70°C or higher. In this case, the heat resistance of the copolymer is improved.

The copolymer of the present invention preferably has a crystal content of 5 to 50%. In this case, the durability of the copolymer is further improved and the workability is also improved.

The rubber composition of the present invention is characterized by containing the above-mentioned copolymer. Such a rubber composition of the present invention has excellent durability.

The resin composition of the present invention is characterized by containing the above-mentioned copolymer. Such a resin composition of the present invention has excellent durability.

The tire of the present invention is characterized by containing the above-mentioned rubber composition. Such a tire of the present invention has excellent durability.

The resin product of the present invention is characterized by containing the above-mentioned resin composition. Such a resin product of the present invention has excellent durability.

According to the present invention, it is possible to provide a copolymer which contains non-conjugated olefin units and substituted butadiene units and has excellent durability.
The present invention can also provide a rubber composition, a resin composition, a tire, and a resin product which contain the copolymer and have excellent durability.

The copolymer, rubber composition, resin composition, tire, and resin product of the present invention will be described in detail below with reference to the embodiments.

［式中、Ｒ^１～Ｒ^６は、それぞれ独立して水素原子又は炭素数１～１２の一価の炭化水素基であり、但し、Ｒ^１～Ｒ^６の内、少なくとも１つは、炭素数１～１２の一価の炭化水素基である。］で表される置換ブタジエン化合物に由来することを特徴とする。 <Copolymer>
The copolymer of the present invention contains non-conjugated olefin units and substituted butadiene units. Here, the copolymer of the present invention has a vinyl bond amount (1,2-vinyl bond amount and 3,4-vinyl bond amount) in the substituted butadiene units of 20 to 60 mol %, a main chain consisting of only acyclic structures, a content of the substituted butadiene units of 25 mol % or more, a weight average molecular weight (Mw) of 50,000 or more, a chain portion in which the substituted butadiene units are chained, and the substituted butadiene units are represented by the following general formula (1):

[wherein R ¹ to R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, provided that at least one of R ¹ to R ⁶ is a monovalent hydrocarbon group having 1 to 12 carbon atoms.]

The copolymer of the present invention contains non-conjugated olefin units, and therefore has better durability than (co)polymers that do not contain non-conjugated olefin units. Furthermore, the copolymer of the present invention has high durability because its main chain is composed only of acyclic structures, contains a chain portion in which substituted butadiene units are linked, has a vinyl bond content within a specific range, and has a substituted butadiene unit content and weight average molecular weight (Mw) that are equal to or greater than a certain value.

The copolymer of the present invention contains non-conjugated olefin units and substituted butadiene units, and may consist of only non-conjugated olefin units and substituted butadiene units, or may further contain other monomer units. In one preferred embodiment of the present invention, the copolymer is an ethylene-isoprene copolymer.

The non-conjugated olefin unit is a structural unit derived from a non-conjugated olefin compound as a monomer. Here, the non-conjugated olefin compound refers to an aliphatic unsaturated hydrocarbon compound having one or more carbon-carbon double bonds. When the non-conjugated olefin compound has two or more carbon-carbon double bonds, the carbon-carbon double bonds are not conjugated. The non-conjugated olefin compound is not particularly limited, but is preferably an α-olefin, and more preferably an α-olefin having 2 to 8 carbon atoms. Specific examples of such α-olefins having 2 to 8 carbon atoms include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. In addition, examples of the non-conjugated olefin compound include heteroatom-substituted alkene compounds such as vinyl pivalate, 1-phenylthioethene, and N-vinylpyrrolidone. The non-conjugated olefin compound may be a single type or a combination of two or more types. In addition, the non-conjugated olefin compound as a monomer is preferably an acyclic non-conjugated olefin compound from the viewpoint of further improving the durability of a rubber composition or a resin composition using the obtained copolymer, and the acyclic non-conjugated olefin compound is preferably an α-olefin, more preferably an α-olefin having 2 to 8 carbon atoms, even more preferably ethylene and propylene, and particularly preferably ethylene. Since acyclic non-conjugated olefin compounds such as α-olefins have a double bond at the α-position of the olefin, they can be efficiently polymerized with a substituted butadiene compound described later, and the durability of a rubber composition or a resin composition using the obtained copolymer can be further improved. In addition, α-olefins having 2 to 8 carbon atoms, particularly ethylene and propylene, are easily available and versatile, and can reduce the production cost of the copolymer.
In the copolymer of the present invention, the non-conjugated olefin unit is preferably a non-cyclic non-conjugated olefin unit. When the non-conjugated olefin unit is a non-cyclic non-conjugated olefin unit, the durability of the rubber composition, resin composition, etc. using the obtained copolymer can be further improved.

In the copolymer of the present invention, the content of the non-conjugated olefin units is preferably 5 to 75 mol%. When the content of the non-conjugated olefin units is 5 mol% or more of the entire copolymer, the durability of the copolymer is further improved. In addition, from the viewpoint of the workability of the copolymer, it is preferable that the content of the non-conjugated olefin units is 75 mol% or less. From the viewpoint of durability, the content of the non-conjugated olefin units is more preferably 10 mol% or more, and even more preferably 20 mol% or more, and from the viewpoint of workability, it is more preferably 74 mol% or less, and even more preferably 72 mol% or less.

［式中、Ｒ^１～Ｒ^６は、それぞれ独立して水素原子又は炭素数１～１２の一価の炭化水素基であり、但し、Ｒ^１～Ｒ^６の内、少なくとも１つは、炭素数１～１２の一価の炭化水素基である。］で表される。 The substituted butadiene unit is a structural unit derived from a substituted butadiene compound as a monomer. Here, the substituted butadiene compound is represented by the following general formula (1):

[In the formula, R ¹ to R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, provided that at least one of R ¹ to R ⁶ is a monovalent hydrocarbon group having 1 to 12 carbon atoms.]

With regard to R ¹ to R ⁶ in the above general formula (1), specific examples of monovalent hydrocarbon groups having 1 to 12 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, neopentyl, hexyl, and octyl; alkenyl groups such as vinyl, allyl, 2-pentenyl, 3-pentenyl, and 4-methyl-3-pentenyl; alkadienyl groups such as butadienyl, pentadienyl, hexadienyl, octadienyl, and 3,7-dimethyl-2,6-octadienyl; aryl groups such as phenyl, tolyl, and naphthyl; and aralkyl groups such as benzyl and phenethyl. Of these, methyl, 4-methyl-3-pentenyl, and 3,7-dimethyl-2,6-octadienyl are preferred.

前記置換ブタジエン化合物は、一種単独であってもよいし、二種以上の組み合わせであってもよい。 Examples of the substituted butadiene compound include isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, myrcene [a compound represented by the following structural formula (1-1), etc.], farnesene [a compound represented by the following structural formula (1-2), etc.], etc.

The substituted butadiene compound may be used alone or in combination of two or more kinds.

Among the substituted butadiene compounds, isoprene, myrcene, and farnesene are preferred. Isoprene, myrcene, and farnesene are available as raw materials derived from natural products. Therefore, from the perspective of sustainability, it is preferred to use isoprene, myrcene, or farnesene as the substituted butadiene compound.

Isoprene is particularly preferred as the substituted butadiene compound. A copolymer obtained by using isoprene as the substituted butadiene compound has good compatibility with natural rubber (NR) when blended with the latter.

In the copolymer of the present invention, the content of the substituted butadiene units is 25 mol% or more, preferably 26 mol% or more, more preferably 28 mol% or more, and preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less. When the content of the substituted butadiene units is 25 mol% or more of the entire copolymer, the copolymer can be easily vulcanized and a copolymer with excellent durability can be obtained, and when the content is 95 mol% or less, the copolymer has excellent weather resistance.

In the copolymer of the present invention, the vinyl bond amount (1,2-vinyl bond amount and 3,4-vinyl bond amount) in the substituted butadiene unit is 20 to 60 mol %. When the vinyl bond amount in the substituted butadiene unit is 20 mol % or more, durability is improved. Furthermore, a copolymer in which the vinyl bond amount in the substituted butadiene unit is 60 mol % or less is easy to produce by the method described below. From the viewpoint of durability, the vinyl bond amount in the substituted butadiene unit is preferably 25 mol % or more, and from the viewpoint of synthesis, it is preferably 55 mol % or less, and more preferably 50 mol % or less.
The vinyl bond amount is the sum of the content of 1,2-bonded substituted butadiene units (i.e., 1,2-vinyl bond amount) and the content of 3,4-bonded substituted butadiene units (i.e., 3,4-vinyl bond amount) in the substituted butadiene units.
In a preferred embodiment of the present invention, the 1,2-vinyl bond amount is 1% by mass or less, and may be 0.5% by mass or less, or may be 0% by mass (below the lower limit of detection by NMR).
The amount of vinyl bonds in the substituted butadiene unit of the copolymer can be controlled to any value by selecting the central metal M and ligands CpR ^' of the half metallocene cation complex represented by the general formula (2) described later.

The copolymer of the present invention preferably has a glass transition temperature (Tg) measured by a differential scanning calorimeter (DSC) of −60° C. to 20° C., and more preferably has a glass transition temperature (Tg) of −29° C. to −15° C. As the vinyl bond content increases, the glass transition temperature tends to increase, so the glass transition temperature can be controlled to an arbitrary value by selecting the central metal M and ligands CpR ^′ of the half metallocene cation complex represented by the general formula (2) described later.
The glass transition temperature is a value measured using a differential scanning calorimeter (DSC) in accordance with JIS K 7121-1987.

The copolymer of the present invention has a polystyrene-equivalent weight average molecular weight (Mw) of 50,000 or more, preferably 100,000 or more, and more preferably 200,000 or more. When the copolymer is used in a rubber composition or a resin composition, if the Mw is 50,000 or more, the durability of the rubber composition or the resin composition can be further improved. Also, from the viewpoint of workability when compounding the copolymer in a rubber composition or a resin composition, the Mw is preferably 4,000,000 or less, and more preferably 3,000,000 or less.

The copolymer of the present invention preferably has a polystyrene-equivalent number average molecular weight (Mn) of 10,000 or more, and more preferably 20,000 or more. When the copolymer is used in a rubber composition or a resin composition, if the Mn is 10,000 or more, the durability of the rubber composition or the resin composition can be further improved. Also, from the viewpoint of workability when compounding the copolymer in a rubber composition or a resin composition, the Mn is preferably 2,000,000 or less, and more preferably 1,500,000 or less.

The copolymer of the present invention preferably has a molecular weight distribution (weight average molecular weight (Mw) in terms of polystyrene/number average molecular weight (Mn) in terms of polystyrene) of 1 to 4. If the molecular weight distribution of the copolymer is 4 or less, sufficient homogeneity can be achieved in the physical properties of the copolymer.

The weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) mentioned above are determined by gel permeation chromatography (GPC) using polystyrene as a standard substance.

The main chain of the copolymer of the present invention is composed only of acyclic structures. This can improve durability. NMR is used as the main measurement method to confirm whether the main chain of the copolymer has a cyclic structure. Specifically, when no peaks derived from the cyclic structures present in the main chain (for example, peaks appearing at 10 to 24 ppm for three- to five-membered rings) are observed, this indicates that the main chain of the copolymer is composed only of acyclic structures.

The copolymer of the present invention contains a chain portion in which the substituted butadiene units are chained. This can improve durability. In order to confirm whether the copolymer contains a chain portion in which the substituted butadiene units are chained, ¹ H-NMR and ¹³ C-NMR are used. Specifically, in the case of ¹ H-NMR, 1,4 bonds are observed at 5.1 ppm and 3,4 bonds at 4.7 ppm (CDCl ₃ ), and in the case of ¹³ C-NMR, 1,4-cis bonds are observed at 23 ppm, 1,4-trans bonds at 16 ppm, and 3,4-vinyl bonds at 18 ppm (CDCl ₃ ), respectively, which indicates that the copolymer contains a chain portion in which the substituted butadiene units are chained.

The copolymer of the present invention has a melting point of preferably 70° C. or higher, more preferably 75° C. or higher, and preferably 130° C. or lower, more preferably 120° C. or lower. If the melting point of the copolymer is 70° C. or higher, the crystallinity of the copolymer is high and the heat resistance is improved, and if the melting point is 130° C. or lower, the workability is improved.
The melting point is a value measured using a differential scanning calorimeter (DSC) in accordance with JIS K 7121-1987.

The copolymer of the present invention preferably has a crystalline amount of 5 to 50%. If the crystalline amount of the copolymer is 5% or more, the crystallinity due to the non-conjugated olefin unit is sufficiently secured, and the durability of the copolymer is further improved. If the crystalline amount of the copolymer is 50% or less, it is preferable from the viewpoint of workability when kneading the rubber composition or resin composition described later. Moreover, from the viewpoint of durability, the crystalline amount is more preferably 10% or more, and even more preferably 14% or more, and from the viewpoint of workability, it is more preferably 40% or less, and even more preferably 30% or less.
The amount of crystallinity of the copolymer can be controlled to any value by selecting the central metal M and ligand CpR ^' of the half metallocene cation complex represented by the general formula (2) described later. The amount of crystallinity corresponds to the amount of continuous non-conjugated olefin units in the copolymer, and it is considered that the amount of crystallinity of the copolymer can be controlled by changing the randomness of monomer conversion by selecting the central metal M and ligand CpR ^' .

The copolymer of the present invention may or may not have a crystalline component. When the copolymer has a crystalline component, the durability of the copolymer is further improved due to the crystal melting energy caused by the crystalline component. On the other hand, when the copolymer does not have a crystalline component, the workability of the copolymer is improved and the operating range as a polymer material is widened (when the copolymer has a crystalline component, the elastic modulus decreases due to melting at a temperature above the crystalline melting point, but this decrease in the elastic modulus can be suppressed).

（式中、Ｍは、ランタノイド元素、スカンジウム又はイットリウムを示し、Ｃｐ^Ｒ’は、２つ以上の置換基を有する、置換シクロペンタジエニル、置換インデニル又は置換フルオレニルを示し、Ｘは、水素原子、ハロゲン原子、アルコキシ基、チオラート基、アミド基、シリル基又は炭素数１～２０の一価の炭化水素基を示し、Ｌは、中性ルイス塩基を示し、ｗは、０～３の整数を示し、［Ｂ］^－は、非配位性アニオンを示す）で表されるハーフメタロセンカチオン錯体を含む重合触媒組成物の存在下で、非共役オレフィン化合物と、置換ブタジエン化合物と、を共重合させることで製造できる。 <Method of Producing Copolymer>
The copolymer of the present invention may be, for example, a copolymer represented by the following general formula (2):

(wherein M represents a lanthanoid element, scandium or yttrium; CpR ^' represents a substituted cyclopentadienyl, substituted indenyl or substituted fluorenyl having two or more substituents; X represents a hydrogen atom, a halogen atom, an alkoxy group, a thiolate group, an amide group, a silyl group or a monovalent hydrocarbon group having 1 to 20 carbon atoms; L represents a neutral Lewis base; w represents an integer of 0 to 3; and [B] ^- represents a non-coordinating anion), thereby producing a copolymer of a non-conjugated olefin compound and a substituted butadiene compound in the presence of a polymerization catalyst composition containing a half metallocene cation complex represented by the following formula:

In the half metallocene cationic complex represented by the above general formula (2), in which CpR ^' has two or more substituents, CpR ^' is bulky, so that copolymerization can proceed stereoregularly due to steric hindrance. In the half metallocene cationic complex represented by the above general formula (2), the vinyl bond amount, glass transition temperature, crystal amount, etc. of the copolymer to be produced can be controlled by changing the central metal M or the ligand CpR ^' .

In the half metallocene cationic complex represented by the above general formula (2), CpR ^' in the formula is a substituted cyclopentadienyl, a substituted indenyl or a substituted fluorenyl, and among these, a substituted indenyl is preferable. When ^CpR' is a substituted indenyl, it becomes easier to control the vinyl bond amount, glass transition temperature, crystal amount, etc. of the copolymer produced.

In the general formula (2), CpR ^' (substituted cyclopentadienyl) having a cyclopentadienyl ring as a basic skeleton can be represented by _{C5H5 - yRy} .
Here, y is the number of substituents R on the cyclopentadienyl ring and is an integer of 1 to 5. y is 2 or more, that is, the number of substituents R is 2 or more. When the number of substituents R is 2 or more, CpR ^' becomes bulky, and the effect of steric hindrance when the substituted butadiene compound approaches the central metal M becomes large, the amount of vinyl bonds tends to increase, and the glass transition temperature tends to increase.
The substituents R are preferably each independently a hydrocarbyl group or a metalloid group. At least one of the substituents R preferably contains Si. The substituent R containing Si can make Cp ^R' bulky while maintaining the stability of the complex, and the effect of steric hindrance when the substituted butadiene compound approaches the central metal M becomes large, making it easier to increase the amount of vinyl bonds and also easier to increase the glass transition temperature. The number of carbon atoms in the hydrocarbyl group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 8. Specific examples of the hydrocarbyl group include methyl, ethyl, tert-butyl, phenyl, and benzyl groups. On the other hand, examples of the metalloid of the metalloid group include germyl Ge and stannyl Sn in addition to silyl Si, and the metalloid group preferably has a hydrocarbyl group, and the hydrocarbyl group of the metalloid group is the same as the hydrocarbyl group described above. Specific examples of the metalloid group include Si-containing substituents such as trimethylsilyl and tert-butyldimethylsilyl groups. Among these, at least one of the substituents R is preferably a bulky substituent such as a tert-butyldimethylsilyl group or a benzyl group. When the substituent R is a bulky substituent, CpR ^' becomes even bulkier, and the effect of steric hindrance when the substituted butadiene compound approaches the central metal M becomes greater, making it easier to increase the amount of vinyl bonds and also easier to increase the glass transition temperature. In addition, when the substituent R is a bulky substituent, the amount of crystals in the copolymer produced tends to decrease, which is thought to be due to improved randomness of monomer conversion.

In the general formula (2), CpR ^' (substituted indenyl) having an indenyl ring as a basic skeleton can be represented by _{C9H7 - yRy} or _{C9H11 - yRy} .
Here, y is the number of substituents R on the indenyl ring and is an integer of 1 to 7 or 1 to 11. y is 2 or more, that is, the substituted indenyl has two or more substituents. When the substituted indenyl has two or more substituents R, CpR ^' becomes bulky, and the effect of steric hindrance when the substituted butadiene compound approaches the central metal M becomes large, the amount of vinyl bonds tends to increase, and the glass transition temperature tends to increase.
In addition, it is preferable that at least one of the substituents R is present on the five-membered ring of the substituted indenyl. Since the substituted indenyl is coordinated to the central metal M on the five-membered ring side, when the substituent R is present on the five-membered ring, the effect of steric hindrance by CpR ^' (substituted indenyl) becomes large when the substituted butadiene compound approaches the central metal M, so that the amount of vinyl bonds tends to increase and the glass transition temperature tends to increase.
The substituents R are preferably each independently a hydrocarbyl group or a metalloid group. At least one of the substituents R preferably contains Si. The substituent R containing Si can make Cp ^R' bulky while maintaining the stability of the complex, and the effect of steric hindrance when the substituted butadiene compound approaches the central metal M becomes large, making it easier to increase the amount of vinyl bonds and also easier to increase the glass transition temperature. The number of carbon atoms in the hydrocarbyl group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 8. Specific examples of the hydrocarbyl group include methyl, ethyl, tert-butyl, phenyl, and benzyl groups. On the other hand, examples of the metalloid of the metalloid group include germyl Ge and stannyl Sn in addition to silyl Si, and the metalloid group preferably has a hydrocarbyl group, and the hydrocarbyl group of the metalloid group is the same as the hydrocarbyl group described above. Specific examples of the metalloid group include Si-containing substituents such as trimethylsilyl and tert-butyldimethylsilyl groups. Among these, at least one of the substituents R is preferably a bulky substituent such as a tert-butyldimethylsilyl group or a benzyl group. When the substituent R is a bulky substituent, Cp ^R' becomes even bulkier, and the effect of steric hindrance when the substituted butadiene compound to be polymerized approaches the central metal M becomes greater, so that the amount of vinyl bonds tends to increase and the glass transition temperature also tends to increase. In addition, when the substituent R is a bulky substituent, the amount of crystals of the copolymer produced tends to decrease, which is thought to be due to improved randomness of monomer conversion.
Specific examples of the substituted indenyl include 1,3-bis(tert-butyldimethylsilyl)indenyl, 1-tert-butyldimethylsilyl-3-trimethylsilyl indenyl, 1,3-bis(trimethylsilyl)indenyl, 1-tert-butyldimethylsilyl-3-benzyl indenyl, 1-tert-butyldimethylsilyl-3-phenyl indenyl, 2-tert-butyldimethylsilyl indenyl, and 2-trimethylsilyl indenyl.

In the general formula (2), CpR ^' (substituted fluorenyl) having a fluorenyl ring as a basic skeleton can be represented by _{C13H9 - yRy} or _{C13H17 - yRy} .
Here, y is the number of substituents R on the fluorenyl ring and is an integer of 1 to 9 or 1 to 17. y is 2 or more, that is, the number of substituents R is 2 or more. When the number of substituents R is 2 or more, CpR ^' becomes bulky, and the effect of steric hindrance when the substituted butadiene compound approaches the central metal M becomes large, the amount of vinyl bonds tends to increase, and the glass transition temperature also tends to increase.
The substituents R are preferably each independently a hydrocarbyl group or a metalloid group. At least one of the substituents R preferably contains Si. The substituent R containing Si can make Cp ^R' bulky while maintaining the stability of the complex, and the effect of steric hindrance when the substituted butadiene compound approaches the central metal M becomes large, making it easier to increase the amount of vinyl bonds and also easier to increase the glass transition temperature. The number of carbon atoms in the hydrocarbyl group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 8. Specific examples of the hydrocarbyl group include methyl, ethyl, tert-butyl, phenyl, and benzyl groups. On the other hand, examples of the metalloid of the metalloid group include germyl Ge and stannyl Sn in addition to silyl Si, and the metalloid group preferably has a hydrocarbyl group, and the hydrocarbyl group of the metalloid group is the same as the hydrocarbyl group described above. Specific examples of the metalloid group include Si-containing substituents such as trimethylsilyl and tert-butyldimethylsilyl groups. Among these, at least one of the substituents R is preferably a bulky substituent such as a tert-butyldimethylsilyl group or a benzyl group. When the substituent R is a bulky substituent, Cp ^R' becomes even bulkier, and the effect of steric hindrance when the substituted butadiene compound to be polymerized approaches the central metal M becomes greater, so that the amount of vinyl bonds tends to increase and the glass transition temperature also tends to increase. In addition, when the substituent R is a bulky substituent, the amount of crystals of the copolymer produced tends to decrease, which is thought to be due to improved randomness of monomer conversion.

The central metal M in the general formula (2) is a lanthanoid element, scandium, or yttrium. The lanthanoid element may be any of the 15 elements having atomic numbers from 57 to 71. Suitable examples of the central metal M include samarium Sm, neodymium Nd, praseodymium Pr, gadolinium Gd, cerium Ce, holmium Ho, scandium Sc, and yttrium Y.
Here, the smaller the atomic radius of the central metal M, the more the vinyl bond amount of the copolymer produced tends to increase, and the higher the glass transition temperature of the copolymer produced. Also, the larger the atomic radius of the central metal M, the more the crystalline amount of the copolymer produced tends to increase, which is believed to be due to the lower randomness of the monomer conversion. Therefore, by using a central metal M with a small atomic radius, the amount of vinyl bonds in the copolymer can be increased (the glass transition temperature of the copolymer can be increased) while the amount of crystals in the copolymer can be reduced. Conversely, by using a central metal M with a large atomic radius, the amount of vinyl bonds in the copolymer can be reduced (the glass transition temperature of the copolymer can be reduced) while the amount of crystals in the copolymer can be increased.
Among the above central metals M, neodymium Nd, gadolinium Gd, holmium Ho, and yttrium Y are preferred, with gadolinium Gd and yttrium Y being more preferred, from the viewpoint of reactivity.

In general formula (2), X represents a hydrogen atom, a halogen atom, an alkoxy group, a thiolate group, an amide group, a silyl group, or a monovalent hydrocarbon group having 1 to 20 carbon atoms. Here, the halogen atom represented by X may be any of a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a chlorine atom or a bromine atom being preferred.

In general formula (2), examples of the alkoxy group represented by X include aliphatic alkoxy groups such as methoxy, ethoxy, propoxy, n-butoxy, isobutoxy, sec-butoxy, and tert-butoxy; and aryloxy groups such as phenoxy, 2,6-di-tert-butylphenoxy, 2,6-diisopropylphenoxy, 2,6-dineopentylphenoxy, 2-tert-butyl-6-isopropylphenoxy, 2-tert-butyl-6-neopentylphenoxy, and 2-isopropyl-6-neopentylphenoxy. Of these, 2,6-di-tert-butylphenoxy is preferred.

In general formula (2), examples of the thiolate group represented by X include aliphatic thiolate groups such as thiomethoxy, thioethoxy, thiopropoxy, thio n-butoxy, thioisobutoxy, thiosec-butoxy, and thiotert-butoxy; and aryl thiolate groups such as thiophenoxy, 2,6-di-tert-butylthiophenoxy, 2,6-diisopropylthiophenoxy, 2,6-dineopentylthiophenoxy, 2-tert-butyl-6-isopropylthiophenoxy, 2-tert-butyl-6-thioneopentylphenoxy, 2-isopropyl-6-thioneopentylphenoxy, and 2,4,6-triisopropylthiophenoxy. Of these, the 2,4,6-triisopropylthiophenoxy group is preferred.

In the general formula (2), examples of the amide group represented by X include aliphatic amide groups such as dimethylamide, diethylamide, and diisopropylamide; aryl amide groups such as phenylamide, 2,6-di-tert-butylphenylamide, 2,6-diisopropylphenylamide, 2,6-dineopentylphenylamide, 2-tert-butyl-6-isopropylphenylamide, 2-tert-butyl-6-neopentylphenylamide, 2-isopropyl-6-neopentylphenylamide, and 2,4,6-tri-tert-butylphenylamide; bis(trialkylsilyl)amide groups such as bis(trimethylsilyl)amide; and bis(dialkylsilyl)amide groups such as bis(dimethylsilyl)amide. Of these, the bis(trimethylsilyl)amide and bis(dimethylsilyl)amide groups are preferred.

In general formula (2), examples of the silyl group represented by X include a trimethylsilyl group, a tris(trimethylsilyl)silyl group, a bis(trimethylsilyl)methylsilyl group, a trimethylsilyl(dimethyl)silyl group, and a triisopropylsilyl(bistrimethylsilyl)silyl group. Of these, the tris(trimethylsilyl)silyl group is preferred.

In general formula (2), specific examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by X include straight-chain or branched-chain aliphatic hydrocarbon groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, neopentyl, hexyl, and octyl; aromatic hydrocarbon groups such as phenyl, tolyl, and naphthyl; aralkyl groups such as benzyl; and silicon-containing hydrocarbon groups such as trimethylsilylmethyl and bistrimethylsilylmethyl. Of these, methyl, ethyl, isobutyl, and trimethylsilylmethyl groups are preferred.

In general formula (2), X is preferably a bis(trimethylsilyl)amide group, a bis(dimethylsilyl)amide group, or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

In the general formula (2), examples of the non-coordinating anion represented by [B] ^- include tetravalent boron anions. Specific examples of the tetravalent boron anion include tetraphenylborate, tetrakis(monofluorophenyl)borate, tetrakis(difluorophenyl)borate, tetrakis(trifluorophenyl)borate, tetrakis(tetrafluorophenyl)borate, tetrakis(pentafluorophenyl)borate, tetrakis(tetrafluoromethylphenyl)borate, tetra(tolyl)borate, tetra(xylyl)borate, (triphenyl,pentafluorophenyl)borate, [tris(pentafluorophenyl),phenyl]borate, and tridecahydride-7,8-dicarbaundecaborate. Among these, tetrakis(pentafluorophenyl)borate is preferred.

The half metallocene cation complex represented by the above general formula (2) further contains 0 to 3, preferably 0 to 1, neutral Lewis bases L. Examples of the neutral Lewis base L include tetrahydrofuran, diethyl ether, dimethylaniline, trimethylphosphine, lithium chloride, neutral olefins, and neutral diolefins. When the complex contains multiple neutral Lewis bases L, the neutral Lewis bases L may be the same or different.

The half metallocene cation complex represented by the above general formula (2) may exist as a monomer, or as a dimer or higher polymer.

The half metallocene cation complex represented by the above general formula (2) can be obtained, for example, by the following reaction.

In the compound represented by the general formula (3) or (4), M represents a lanthanoid element, scandium or yttrium, CpR ^' each independently represents a substituted cyclopentadienyl, a substituted indenyl or a substituted fluorenyl, X each independently represents a hydrogen atom, a halogen atom, an alkoxy group, a thiolate group, an amide group, a silyl group or a monovalent hydrocarbon group having 1 to 20 carbon atoms, L represents a neutral Lewis base, and w represents an integer of 0 to 3. In the ionic compound represented by the general formula [A] ⁺ [B] ^- , [A] ⁺ represents a cation and [B] ^- represents a non-coordinating anion.

[A] Examples of the cation represented by ⁺ include a carbonium cation, an oxonium cation, an amine cation, a phosphonium cation, a cycloheptatrienyl cation, and a ferrocenium cation having a transition metal. Examples of the carbonium cation include tri-substituted carbonium cations such as a triphenylcarbonium cation (also called a "trityl cation") and a tri(substituted phenyl)carbonium cation. Specific examples of the tri(substituted phenyl)carbonium cation include a tri(methylphenyl)carbonium cation. Examples of the amine cation include trialkylammonium cations such as a trimethylammonium cation, a triethylammonium cation, a tripropylammonium cation, and a tributylammonium cation; N,N-dimethylanilinium cation, N,N-diethylanilinium cation, and N,N-2,4,6-pentamethylanilinium cation; and dialkylammonium cations such as a diisopropylammonium cation and a dicyclohexylammonium cation. Examples of the phosphonium cation include triarylphosphonium cations such as triphenylphosphonium cation, tri(methylphenyl)phosphonium cation, and tri(dimethylphenyl)phosphonium cation. Among these cations, N,N-dialkylanilinium cation or carbonium cation is preferred, and N,N-dialkylanilinium cation is particularly preferred.

The ionic compound represented by the general formula [A] ⁺ [B] ^- used in the above reaction is a compound selected from the above non-coordinating anions and cations and combined, and is preferably N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, triphenylcarbonium tetrakis(pentafluorophenyl)borate (also called "trityltetrakis(pentafluorophenyl)borate"), etc. The ionic compound represented by the general formula [A] ⁺ [B] ^- is preferably added in an amount of 0.1 to 10 times by mole, more preferably about 1 time by mole, relative to the compound represented by the general formula (3) or (4). In addition, when the half metallocene cationic complex represented by the general formula (2) is used in a polymerization reaction, the half metallocene cationic complex represented by the general formula (2) may be provided as it is in a polymerization reaction system, or the compound represented by the general formula (3) or (4) and the ionic compound represented by the general formula [A] ⁺ [B] ^- used in the above reaction may be provided separately in the polymerization reaction system to form the half metallocene cationic complex represented by the general formula (2) in the reaction system.

The structure of the half metallocene cation complex represented by the above general formula (2) can be determined by X-ray structural analysis.
In the polymerization reaction system, the concentration of the half metallocene cationic complex contained in the polymerization catalyst composition is preferably in the range of 0.0001 to 0.1 mol/L.

The polymerization catalyst composition may further contain other components, such as a cocatalyst, contained in a polymerization catalyst composition containing a normal metallocene complex. Here, the metallocene complex is a complex compound in which one or more cyclopentadienyls or derivatives thereof are bonded to a central metal, and in this specification, a metallocene complex in which one cyclopentadienyl or derivative thereof (indenyl, fluorenyl, etc.) is bonded to the central metal is referred to as a half-metallocene complex.

The cocatalyst that can be used in the above polymerization catalyst composition can be arbitrarily selected from components that are used as cocatalysts in polymerization catalyst compositions that contain ordinary metallocene complexes. Suitable examples of the cocatalyst include aluminoxanes, organoaluminum compounds, and the above ionic compounds. These cocatalysts may be used alone or in combination of two or more.

The aluminoxane is preferably an alkylaluminoxane, such as methylaluminoxane (MAO) or modified methylaluminoxane. As the modified methylaluminoxane, MMAO-3A (manufactured by Toso Finechem Co., Ltd.) is preferred. The content of the aluminoxane in the polymerization catalyst composition is preferably such that the element ratio (Al/M) of the aluminum element Al of the aluminoxane to the central metal M of the half metallocene cation complex is about 10 to 1000, preferably about 100.

On the other hand, the organoaluminum compound is represented by the following general formula (5):
AlR ⁷ R ⁸ R ⁹ ... (5)
(wherein R ⁷ and R ⁸ are each independently a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom, and R ⁹ is a hydrocarbon group having 1 to 10 carbon atoms). Examples of the organoaluminum compound include trialkylaluminum and dialkylaluminum hydride, and among these, trialkylaluminum is preferred. Examples of trialkylaluminum include triethylaluminum and triisobutylaluminum, and examples of dialkylaluminum hydride include diisobutylaluminum hydride. The content of the organoaluminum compound in the polymerization catalyst composition is preferably 1 to 50 times by mol, and more preferably about 10 times by mol, relative to the half metallocene cation complex.

In the above polymerization catalyst composition, the vinyl bond amount and molecular weight of the resulting copolymer can be controlled by combining the half metallocene cationic complex represented by general formula (2) with an appropriate cocatalyst.

The polymerization catalyst composition preferably does not contain a halogen compound. In conventional polymerization reactions using half-metallocene cationic complexes or metallocene complexes, when an organoaluminum compound is used as a cocatalyst, a halogen compound such as dialkylaluminum chloride or alkylaluminum dichloride is often used. However, by not using a halogen compound in combination with the half-metallocene cationic complex represented by general formula (2), a copolymer with a high vinyl bond content can be obtained.

The copolymer of the present invention can be produced through a process of copolymerizing a non-conjugated olefin compound and a substituted butadiene compound in the presence of the above-mentioned polymerization catalyst composition (hereinafter also referred to as a copolymerization process), and may further include a coupling process, a washing process, and other processes as necessary. In addition to the non-conjugated olefin compound and the substituted butadiene compound, other monomers can also be copolymerized.

As a polymerization method in the copolymerization step, any method such as solution polymerization, suspension polymerization, liquid phase bulk polymerization, emulsion polymerization, gas phase polymerization, solid phase polymerization, etc. can be used. In addition, when a solvent is used in the polymerization reaction, the solvent may be any solvent that is inert in the polymerization reaction, such as toluene, hexane (e.g., cyclohexane, normal hexane), etc., among which hexane is preferred. When polymerization is performed using hexane as a solvent, the environmental load can be reduced.

In the presence of the above-mentioned polymerization catalyst composition, the content of non-conjugated olefin units, substituted butadiene units, and bond content (amount of cis-1,4 bonds, amount of trans-1,4 bonds, amount of 3,4-vinyl bonds, and amount of 1,2-vinyl bonds) in the produced copolymer can also be controlled by controlling reaction conditions such as reaction temperature, reaction time, and the amount and ratio of the non-conjugated olefin compound and the substituted butadiene compound.

In the copolymerization step, the polymerization reaction is preferably carried out under an atmosphere of an inert gas, preferably nitrogen gas or argon gas. The polymerization temperature of the polymerization reaction is not particularly limited, but is preferably in the range of -100°C to 200°C, and can be about room temperature. The pressure of the polymerization reaction is preferably in the range of 0.1 to 10.0 MPa. The reaction time of the polymerization reaction is not particularly limited, but is preferably in the range of 1 second to 10 days, and can be appropriately selected depending on the conditions such as the desired microstructure, type of catalyst, and polymerization temperature for the resulting copolymer.
In the copolymerization step, the polymerization may be terminated using a polymerization terminator such as methanol, ethanol, isopropanol, etc.

The coupling step is a step of carrying out a reaction (coupling reaction) for modifying at least a part (for example, a terminal) of the copolymer obtained in the copolymerization step.
In the coupling step, it is preferable to carry out the coupling reaction when the polymerization reaction reaches 100%.
The coupling agent used in the coupling reaction is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include tin-containing compounds such as bis(1-octadecyl maleate)dioctyltin(IV) and the like; isocyanate compounds such as 4,4'-diphenylmethane diisocyanate and the like; alkoxysilane compounds such as glycidylpropyltrimethoxysilane and the like. These may be used alone or in combination of two or more kinds. Among these, bis(1-octadecyl maleate)dioctyltin(IV) is preferred in terms of reaction efficiency and low gel formation.
By carrying out the coupling reaction, the number average molecular weight (Mn) and weight average molecular weight (Mw) of the copolymer can be increased.

The washing step is a step of washing the copolymer obtained in the copolymerization step. The medium used for washing is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include methanol, ethanol, isopropanol, etc., and these solvents can also be used by adding an acid (e.g., hydrochloric acid, sulfuric acid, nitric acid). The amount of acid added is preferably 15 mol% or less relative to the solvent. If the amount is more than this, the acid may remain in the copolymer, which may adversely affect the reaction during kneading and vulcanization.
This washing step makes it possible to suitably reduce the amount of catalyst residue in the copolymer.

<Rubber Composition>
The rubber composition of the present invention is characterized by containing the above-mentioned copolymer, and has excellent durability.
The rubber composition of the present invention contains the above-mentioned copolymer as a rubber component, and may further contain other rubber components, fillers, crosslinking agents, resin components, softeners, and other components, as necessary.

In the rubber composition of the present invention, the content of the copolymer in the rubber component is preferably in the range of 10 to 100% by mass, more preferably in the range of 20 to 100% by mass, and even more preferably in the range of 30 to 100% by mass. If the content of the copolymer in the rubber component is 10% by mass or more, the effect of the copolymer is fully exerted, and the durability of the rubber composition is further improved.

The other rubber components are not particularly limited and can be appropriately selected depending on the purpose. Examples include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), polysulfide rubber, silicone rubber, fluororubber, urethane rubber, etc. These may be used alone or in combination of two or more.

The rubber composition of the present invention preferably contains a filler. When the rubber composition contains a filler, the reinforcing property of the rubber composition can be improved. The filler is not particularly limited, and examples thereof include carbon black, silica, aluminum hydroxide, clay, alumina, talc, mica, kaolin, glass balloons, glass beads, calcium carbonate, magnesium carbonate, magnesium hydroxide, magnesium oxide, titanium oxide, potassium titanate, barium sulfate, etc., among which carbon black, silica, and aluminum hydroxide are preferred, and carbon black and silica are more preferred. These may be used alone or in combination of two or more.
Examples of the carbon black include GPF, FEF, HAF, ISAF and SAF grade carbon black.
Examples of the silica include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, and aluminum silicate. Among these, wet silica is preferred.
As the aluminum hydroxide, it is preferable to use Hidilite (registered trademark, manufactured by Showa Denko KK) or the like.
The content of the filler is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 to 120 parts by mass, more preferably 20 to 100 parts by mass, and particularly preferably 30 to 80 parts by mass, per 100 parts by mass of the rubber component. When the content of the filler is 10 parts by mass or more, the effect of improving the reinforcing property by blending the filler can be sufficiently obtained, and when it is 120 parts by mass or less, good workability can be maintained.

When the rubber composition of the present invention contains silica as the filler, it is preferable that the rubber composition contains a silane coupling agent.
Here, the silane coupling agent (g) is not particularly limited. For example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl-N,N-dimethyl Examples of the silane coupling agent include thiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, 3-trimethoxysilylpropyl methacrylate monosulfide, bis(3-diethoxymethylsilylpropyl)tetrasulfide, 3-mercaptopropyldimethoxymethylsilane, dimethoxymethylsilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, dimethoxymethylsilylpropyl benzothiazolyl tetrasulfide, etc. These silane coupling agents may be used alone or in combination of two or more.
The content of the silane coupling agent is preferably in the range of 3 to 15 parts by mass relative to the content of silica (when the content of silica is 100 parts by mass), and more preferably in the range of 5 to 15 parts by mass. If the content of the silane coupling agent is 3 parts by mass or more relative to 100 parts by mass of silica, the effect of improving the high elastic modulus and fracture resistance due to silica is sufficiently exhibited, and if the content of the silane coupling agent is 15 parts by mass or less relative to 100 parts by mass of silica, gelation of the rubber component can be reliably suppressed.

The rubber composition of the present invention preferably contains a crosslinking agent when crosslinking. The crosslinking agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the crosslinking agent include sulfur-based crosslinking agents, organic peroxide-based crosslinking agents, inorganic crosslinking agents, polyamine crosslinking agents, resin crosslinking agents, sulfur compound-based crosslinking agents, and oxime-nitrosamine-based crosslinking agents. Among these, sulfur-based crosslinking agents (vulcanizing agents) are more preferable for rubber compositions for tires.
The content of the crosslinking agent is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the rubber component.

When the vulcanizing agent is used, a vulcanization accelerator may be used in combination with the vulcanizing agent. Examples of the vulcanization accelerator include guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, and xanthate-based compounds.
The content of the vulcanization accelerator is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 to 20 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the rubber component.

The rubber composition of the present invention preferably contains a resin component as necessary. When the rubber composition contains a resin component, the workability of the rubber composition is further improved. In addition, when the rubber composition contains a resin component together with the copolymer, the high durability derived from the copolymer is maintained, and a rubber composition having excellent tackiness when adhering to other members during molding of tires, etc. can be obtained, which also leads to improvement in productivity of tires, etc.
As the resin component, various natural resins and synthetic resins can be used, and specifically, it is preferable to use rosin-based resins, terpene-based resins, petroleum-based resins, phenol-based resins, coal-based resins, xylene-based resins, etc. These resin components may be used alone or in combination of two or more kinds.
The content of the resin component is not particularly limited and can be appropriately selected depending on the purpose. However, the content is preferably 5 to 150 parts by mass, more preferably 5 to 100 parts by mass, even more preferably 10 to 80 parts by mass, and particularly preferably 10 to 50 parts by mass, relative to 100 parts by mass of the rubber component.

The rubber composition of the present invention preferably contains a softener as necessary. When the rubber composition contains a softener, the workability of the rubber composition is further improved.
Examples of the softener include mineral oil derived from minerals, aromatic oil derived from petroleum, paraffinic oil, naphthenic oil, palm oil derived from natural products, etc. Among these, from the viewpoint of the wear resistance of the rubber composition, softeners derived from minerals and softeners derived from petroleum are preferred.
The content of the softener is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 to 150 parts by mass, more preferably 1 to 130 parts by mass, and even more preferably 5 to 110 parts by mass, per 100 parts by mass of the rubber component.

In addition, the rubber composition of the present invention may contain known additives such as vulcanization aids, colorants, flame retardants, lubricants, antioxidants, scorch inhibitors, UV inhibitors, antistatic agents, color inhibitors, and other compounding agents, depending on the intended use.

In addition to the tire applications described below, the rubber composition of the present invention can also be used in vibration-proof rubber, seismic isolation rubber, belts such as conveyor belts, rubber crawlers, various hoses, etc.

<Resin Composition>
The resin composition of the present invention is characterized by containing the above-mentioned copolymer, and has excellent durability.
The resin composition of the present invention contains the above-mentioned copolymer as a resin component, and may further contain other resin components and various additives, if necessary.
In the present invention, when the resin composition contains the above-mentioned copolymer, the copolymer is treated as a resin component, and the content of the above-mentioned copolymer in the resin component is preferably 10% by mass or more.

Examples of the other resin component include polyolefins such as polyethylene and polypropylene, polyamides, polyester-based thermoplastic elastomers, and polyesters such as polybutylene terephthalate and polybutylene naphthalate. Only one type of the other resin component may be used, or two or more types may be used.
Examples of additives include antistatic agents, lubricants, crystal nucleating agents, tackifiers, antifogging agents, release agents, plasticizers, fillers, antioxidants, pigments, dyes, fragrances, and flame retardants.

<Tires>
The tire of the present invention is characterized by including the above-mentioned rubber composition. It can also be said that the tire of the present invention comprises a vulcanized rubber obtained by vulcanizing the above-mentioned rubber composition. Such a tire of the present invention has excellent durability.
The application site of the rubber composition of the present invention in a tire is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include tread, base tread, sidewall, side reinforcing rubber, bead filler, etc., but it is preferably used in the tread. A tire using the rubber composition of the present invention in the tread is a tire excellent in workability during manufacturing and durability.
The tire of the present invention can be manufactured according to a conventional method without any particular limitation, except that the above-mentioned rubber composition of the present invention is used for any of the tire components. The tire of the present invention is preferably a pneumatic tire, and the gas to be filled in the pneumatic tire can be normal air or air with an adjusted oxygen partial pressure, or an inert gas such as nitrogen, argon, or helium.

<Resin products>
The resin product of the present invention is characterized by containing the above-mentioned resin composition. Such a resin product of the present invention has excellent durability.
The use of the resin product of the present invention is not particularly limited, and the resin product can be applied to various articles having at least a resin portion.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

(Comparative Example 1)
Into a thoroughly dried 1 L pressure-resistant glass reactor, 369 g of a toluene solution containing 80 g of isoprene and 21 g of toluene were added.
In a glove box under a nitrogen atmosphere, 12 μmol of bis(1-benzylindenyl)mono(bis(dimethylsilyl)amide)neodymium complex {[1-PhCH ₂ C ₉ H ₅ ] ₂ Nd[N(SiHMe ₂ ) ₂ ]}, 0.24 mmol of triisobutylaluminum, 0.60 mmol of diisobutylaluminum hydride, and 5 mL of toluene were charged into a 1 L pressure-resistant glass reactor, and the mixture was aged for 30 minutes. Then, 12 μmol of triphenylcarbonium tetrakis(pentafluorophenyl)borate [Ph ₃ CB(C ₆ F ₅ ) ₄ ] was charged, and the mixture was aged for another 30 minutes.
Thereafter, the reactor was taken out of the glove box, and added to the 1 L pressure-resistant glass reactor, followed by reaction at room temperature for 900 minutes.
After the polymerization, 1 mL of a 5% by mass solution of 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol) (NS-5) in isopropanol was added to terminate the reaction, and the polymer was separated with a large amount of methanol and vacuum dried at 50°C to obtain a polymer (polyisoprene). The yield of the obtained polymer was 60 g.

(Comparative Example 2)
Into a thoroughly dried 1 L pressure-resistant glass reactor, 369 g of a toluene solution containing 80 g of isoprene and 21 g of toluene were added.
In a glove box under a nitrogen atmosphere, 12 μmol of bis(1-benzylindenyl)mono(bis(dimethylsilyl)amide)neodymium complex {[1-PhCH ₂ C ₉ H ₅ ] ₂ Nd[N(SiHMe ₂ ) ₂ ], 0.24 mmol of triisobutylaluminum, 0.36 mmol of diisobutylaluminum hydride, and 5 mL of toluene were charged into a 1 L pressure-resistant glass reactor, and the mixture was then aged for 30 minutes. Then, 12 μmol of triphenylcarbonium tetrakis(pentafluorophenyl)borate [Ph ₃ CB(C ₆ F ₅ ) ₄ ] was charged, and the mixture was further aged for 30 minutes.
Thereafter, the reactor was taken out of the glove box, and added to the 1 L pressure-resistant glass reactor, followed by reaction at room temperature for 900 minutes.
After the polymerization, 1 mL of a 5% by mass solution of 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol) (NS-5) in isopropanol was added to terminate the reaction, and the polymer was separated using a large amount of methanol and vacuum dried at 50°C to obtain a polymer (polyisoprene). The yield of the obtained polymer was 72 g.

(Comparative Example 3)
Into a thoroughly dried 1 L pressure-resistant glass reactor, 460 g of a toluene solution containing 100 g of isoprene and 31 g of toluene were added.
In a glove box under a nitrogen atmosphere, 10 μmol of mono(bis(1,3-tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex {1,3-[(t-Bu)Me ₂ Si] ₂ C ₉ H ₅ Gd[N(SiHMe ₂ ) ₂ ] ₂ }, 0.20 mmol of triisobutylaluminum, 1.50 mmol of diisobutylaluminum hydride, and 5 mL of toluene were charged into a 1 L pressure-resistant glass reactor, and the mixture was aged for 30 minutes. Then, 10 μmol of triphenylcarbonium tetrakis(pentafluorophenyl)borate [Ph ₃ CB(C ₆ F ₅ ) ₄ ] was charged, and the mixture was aged for another 30 minutes.
Thereafter, the reactor was taken out of the glove box, and added to the 1 L pressure-resistant glass reactor, followed by reaction at room temperature for 240 minutes.
After the polymerization, 1 mL of a 5% by mass solution of 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol) (NS-5) in isopropanol was added to terminate the reaction, and the polymer was separated with a large amount of methanol and vacuum dried at 50°C to obtain a polymer (polyisoprene). The yield of the obtained polymer was 95 g.

(Comparative Example 4)
Into a thoroughly dried 1 L pressure-resistant glass reactor, 460 g of a toluene solution containing 100 g of isoprene and 35 g of toluene were added.
In a glove box under a nitrogen atmosphere, 5.0 μmol of mono(bis(1,3-tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex {1,3-[(t-Bu)Me ₂ Si] ₂ C ₉ H ₅ Gd[N(SiHMe ₂ ) ₂ ] ₂ }, 0.20 mmol of triisobutylaluminum, 0.90 mmol of diisobutylaluminum hydride, and 5 mL of toluene were charged into a 1 L pressure-resistant glass reactor, and the mixture was aged for 30 minutes. Then, 5 μmol of triphenylcarbonium tetrakis(pentafluorophenyl)borate [Ph ₃ CB(C ₆ F ₅ ) ₄ ] was charged, and the mixture was aged for another 30 minutes.
Thereafter, the reactor was taken out of the glove box, and added to the 1 L pressure-resistant glass reactor, followed by reaction at room temperature for 900 minutes.
After the polymerization, 1 mL of a 5% by mass solution of 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol) (NS-5) in isopropanol was added to terminate the reaction, and the polymer was separated with a large amount of methanol and vacuum dried at 50°C to obtain a polymer (polyisoprene). The yield of the obtained polymer was 95 g.

(Comparative Example 5)
Into a thoroughly dried 1 L pressure-resistant glass reactor, 461 g of a toluene solution containing 100 g of isoprene and 31 g of toluene were added.
In a glove box under a nitrogen atmosphere, 0.010 mmol of mono(bis(1,3-tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide)holmium complex {1,3-[(t-Bu)Me ₂ Si] ₂ C ₉ H ₅ Ho[N(SiHMe ₂ ) ₂ ] ₂ }, 0.010 mmol of trityltetrakis(pentafluorophenyl)borate [Ph ₃ CB(C ₆ F ₅ ) ₄ ], 0.20 mmol of triisobutylaluminum, and 1.8 mmol of diisobutylaluminum hydride were charged into a glass vessel, and 5 mL of toluene was added to prepare a catalyst solution. The catalyst solution was added to the 1 L pressure-resistant glass reactor, and the reaction was carried out at 50° C. for 900 minutes.
The reaction was stopped by adding 1 mL of a 5% by weight solution of 2,2'-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) in isopropanol to the 1 L pressure-resistant glass reactor.
Then, the polymer was separated using a large amount of methanol and vacuum dried at 50° C. to obtain 90 g of the polymer.

(Comparative Example 6)
Into a thoroughly dried 1 L pressure-resistant glass reactor, 368 g of a toluene solution containing 80 g of isoprene and 25 g of toluene were added.
In a glove box under a nitrogen atmosphere, 0.008 mmol of mono(bis(1,3-tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide)holmium complex {1,3-[(t-Bu)Me ₂ Si] ₂ C ₉ H ₅ Ho[N(SiHMe ₂ ) ₂ ] ₂ }, 0.010 mmol of trityltetrakis(pentafluorophenyl)borate [Ph ₃ CB(C ₆ F ₅ ) ₄ ], 0.16 mmol of triisobutylaluminum, and 2.4 mmol of diisobutylaluminum hydride were charged into a glass vessel, and 5 mL of toluene was added to prepare a catalyst solution. The catalyst solution was added to the 1 L pressure-resistant glass reactor, and the reaction was carried out at room temperature for 900 minutes.
The reaction was stopped by adding 1 mL of a 5% by weight solution of 2,2'-methylene-bis(4-ethyl-6-t-butylphenol) (NS-5) in isopropanol to the 1 L pressure-resistant glass reactor.
Then, the polymer was separated using a large amount of methanol and dried in vacuum at 50° C. to obtain 65 g of the polymer.

Example 1
Into a thoroughly dried 2000 mL pressure-resistant stainless steel reactor, 691 g of a toluene solution containing 150 g of isoprene and 59 g of toluene were placed.
In a glove box under a nitrogen atmosphere, 5.0 μmol of mono(bis(1,3-tert-butyldimethylsilyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex {1,3-[(t-Bu)Me ₂ Si] ₂ C ₉ H ₅ Gd[N(SiHMe ₂ ) ₂ ] ₂ }, 0.1 mmol of triisobutylaluminum, and 2.50 mmol of diisobutylaluminum hydride were placed in a glass vessel, and 5.0 mL of toluene was added to prepare a catalyst solution. The catalyst solution was added to the pressure-resistant stainless steel reactor and heated to 60° C.
Next, ethylene was charged into the pressure-resistant stainless steel reactor at a pressure of 1.0 MPa, and copolymerization was carried out at 85° C. for a total of 180 minutes.
Next, 1 mL of a 5% by mass solution of 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol) (NS-5) in isopropanol was added to the pressure-resistant stainless steel reactor to terminate the reaction.
Next, the copolymer was separated using a large amount of methanol and vacuum dried at 50° C. to obtain 118 g of a copolymer (ethylene-isoprene copolymer).

Example 2
Into a thoroughly dried 2000 mL pressure-resistant stainless steel reactor, 380 g of a toluene solution containing 82 g of isoprene and 370 g of toluene were placed.
In a glove box under a nitrogen atmosphere, 0.010 mmol of mono((1-tert-butyldimethylsilyl-3-benzyl)indenyl)bis(bis(dimethylsilyl)amide)gadolinium complex {1-[(t-Bu)Me ₂ Si]-3-BnC ₉ H ₅ Gd[N(SiHMe ₂ ) ₂ ] ₂ }, 0.010 mmol of trityltetrakis(pentafluorophenyl)borate [Ph ₃ CB(C ₆ F ₅ ) ₄ ], 0.020 mmol of triisobutylaluminum, and 2.5 mmol of diisobutylaluminum hydride were placed in a glass vessel, and 5 mL of toluene was added to prepare a catalyst solution. The catalyst solution was added to the pressure-resistant stainless steel reactor and heated to 85°C.
Next, ethylene was introduced into the pressure-resistant stainless steel reactor at a pressure of 1.0 MPa, and copolymerization was carried out for a total of 2 hours and 5 minutes at 85° C. When the supply of ethylene was stopped 30 minutes after the start of the introduction of ethylene, the ethylene pressure changed from 1.0 MPa to 0.5 MPa.
Next, 1 mL of a 5% by mass solution of 2,2'-methylene-bis(4-ethyl-6-tert-butylphenol) (NS-5) in isopropanol was added to the pressure-resistant stainless steel reactor to terminate the reaction.
Next, the copolymer was separated using a large amount of methanol and vacuum dried at 50° C. to obtain 80 g of a copolymer (ethylene-isoprene copolymer).

<Analysis of (co)polymer>
The weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw/Mn), ethylene unit and isoprene unit contents, vinyl bond amounts (1,2-vinyl bond amount, 3,4-vinyl bond amount), glass transition temperature (Tg), melting point (Tm), and crystal amount of the obtained (co)polymer were measured by the following methods, and further the main chain structure and chain structure were confirmed. The results are shown in Table 1.

(1) Weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw/Mn)
(1-1) The weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) of the polymers of the comparative examples were measured as follows.
Each of the obtained weight fractions was analyzed by gel permeation chromatography [GPC: HLC-8320GPC manufactured by Tosoh Corporation, column: GMH _HL × 2 manufactured by Tosoh Corporation, detector: differential refractometer (RI)] using monodisperse polystyrene as a standard. The polystyrene-equivalent weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) of the polymer were determined. The measurement temperature was 40° C., the measurement flow rate was 1 mL/min, and the mobile phase was tetrahydrofuran ( THF), the solution concentration was 1 mg/mL, and the injection volume was 100 μL.

(1-2) The weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) of the copolymers in the examples were measured as follows.
The weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of the copolymer in terms of polystyrene were determined by gel permeation chromatography [GPC: HLC-8220GPC/HT manufactured by Tosoh Corporation, column: 2 GMHHR-H(S)HT manufactured by Tosoh Corporation, detector: differential refractometer (RI)] using monodisperse polystyrene as a standard. The measurement temperature was 140° C., the measurement flow rate was 1 mL/min, the mobile phase was tetrahydrofuran (THF), the solution concentration was 1 mg/mL, and the injection amount was 100 μL.

(2) Contents of Ethylene Units and Isoprene Units The contents of ethylene units and isoprene units in the copolymer were determined from the integral ratio of each peak in ¹ H-NMR spectrum (100° C., d-tetrachloroethane standard: 6 ppm).

(3) Vinyl bond content (1,2-vinyl bond content, 3,4-vinyl bond content)
For each of the (co)polymers obtained, an NMR spectrum was obtained using an NMR (AVANCE 600, manufactured by Bruker). The 1,2-vinyl bond amount and 3,4-vinyl bond amount were calculated from the integral ratio of the peaks obtained by ¹ H-NMR and ¹³ C-NMR measurements ( ¹ H-NMR: δ 4.6-4.8 (=CH ₂ of 3,4-vinyl unit), 5.0-5.2 (-CH= of 1,4-unit), 5.6-5.8 (-CH= of 1,2-unit), 4.8-4.9 (=CH ₂ of 1,2-unit), ¹³ C-NMR: δ 23.4 (1,4-cis unit), 15.9 (1,4-trans unit, 18.6 (3,4-unit)), and the vinyl bond amount was calculated from the sum thereof.

(4) Glass transition temperature (Tg)
The glass transition temperature (Tg) of the (co)polymer was measured using a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan, "DSCQ2000") in accordance with JIS K 7121-1987.

(5) Melting point (Tm)
The melting point (Tm) of the (co)polymer was measured using a differential scanning calorimeter (DSC, manufactured by TA Instruments Japan, "DSCQ2000") in accordance with JIS K 7121-1987.

(6) Crystallinity A differential scanning calorimeter (DSC, manufactured by TA Instruments Japan, "DSCQ2000") was used to measure the endothermic peak energy (ΔH) of the (co)polymer and the crystalline melting energy (ΔH ₀ ) of the 100% crystalline polyethylene by heating from -150°C to 150°C at a rate of 10°C/min, and the crystallinity (%) was calculated from the energy ratio (ΔH/ΔH ₀ ) between the (co)polymer and the polyethylene.

(7) Confirmation of main chain structure ^{The 13} C-NMR spectrum of the obtained (co)polymers was measured. Since no peak was observed at 10 to 24 ppm in the ¹³ C-NMR spectrum chart of any of the (co)polymers, it was confirmed that the main chain of the (co)polymers was composed only of acyclic structures.

(8) Confirmation of chain structure The NMR spectrum of the copolymers of the examples was measured. For all of the copolymers, in the case of ¹ H-NMR, 1,4 bonds were observed at 5.1 ppm and 3,4 bonds at 4.7 ppm (CDCl ₃ ), and in the case of ¹³ C-NMR, 1,4-cis bonds were observed at 23 ppm, 1,4-trans bonds at 16 ppm, and 3,4-vinyl bonds at 18 ppm (CDCl ₃ ), respectively, confirming that isoprene units (substituted butadiene units) were chained.

<Preparation and Evaluation of Rubber Composition>
A rubber composition was produced using a conventional Banbury mixer according to the compounding recipe shown in Table 2. The durability of the rubber composition was evaluated by the following method. The results are shown in Table 2.

(9) Durability The obtained rubber composition was vulcanized by a conventional method to prepare a vulcanized rubber, and a 2 mm thick sheet of the vulcanized rubber was processed into a ring shape to prepare a vulcanized rubber test piece. A tensile test was performed on the test piece at 25°C to measure the maximum tensile stress (Tb, MPa) required to break the test piece, and the tensile stress at break (Tb) of Comparative Example 1 was set to 100, and each value was expressed as an index. A larger index value indicates a larger tensile stress at break (Tb) and better durability.

*1 Silica: Tosoh Silica Industries Co., Ltd., product name "Nipsil AQ"
*2 Silane coupling agent: Bis(3-triethoxysilylpropyl)disulfide, (average sulfur chain length: 2.35), manufactured by Evonik, trade name "Si75" (registered trademark)
*3 Wax: Microcrystalline wax, manufactured by Seiko Chemical Co., Ltd., product name "Suntite"
*4 Antioxidant 6C: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocrac 6C"
*5 Vulcanization accelerator DPG: 1,3-diphenylguanidine, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Suncerer D"
*6 Vulcanization accelerator DM: Di-2-benzothiazolyl disulfide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Suncerer DM"
*7 Vulcanization accelerator NS: N-tert-butyl-2-benzothiazolyl sulfenamide, manufactured by Sanshin Chemical Industry Co., Ltd., trade name "Suncerer NS"
*8 Zinc oxide: Zinc oxide, manufactured by Hakusui Tech Co., Ltd.

From Table 2, it can be seen that the rubber compositions of Examples 3 and 4, which contain the copolymers of Examples 1 and 2, have excellent durability.

The copolymer of the present invention can be used as a rubber component of a rubber composition or a resin component of a resin composition. The rubber composition of the present invention can be used for various rubber products, including tires. The resin composition of the present invention can be used for various resin products.

Claims (12)

A copolymer comprising non-conjugated olefin units and substituted butadiene units,
the non-conjugated olefin units are derived exclusively from ethylene;
the amount of vinyl bonds (1,2-vinyl bonds and 3,4-vinyl bonds) in the substituted butadiene units is 20 to 60 mol %,
The main chain is composed only of acyclic structures,
The content of the substituted butadiene unit is 25 mol% or more,
The weight average molecular weight (Mw) is 50,000 or more,
The substituted butadiene units are linked together,
The substituted butadiene unit is represented by the following general formula (1):
[wherein R ¹ to R ⁶ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms, provided that at least one of R ¹ to R ⁶ is a monovalent hydrocarbon group having 1 to 12 carbon atoms.] The copolymer according to claim 1, wherein the content of the non-conjugated olefin units is 5 to 65 mol%. 3. The copolymer of claim 1 or 2 , wherein the substituted butadiene compound is selected from at least one of isoprene, myrcene, and farnesene. The copolymer of claim 3 , wherein the substituted butadiene compound is isoprene. The copolymer according to any one of claims 1 to 4, wherein the substituted butadiene compound consists solely of isoprene. The copolymer according to any one of claims 1 to 5, wherein the copolymer containing non-conjugated olefin units and substituted butadiene units is an ethylene-isoprene copolymer. The copolymer according to any one of claims 1 to 6, having a melting point of 70°C or higher. The copolymer according to any one of claims 1 to 7, having a crystal content of 5 to 50%. A rubber composition comprising the copolymer according to any one of claims 1 to 8. A resin composition comprising the copolymer according to any one of claims 1 to 8. A tire comprising the rubber composition according to claim 9. A resin product comprising the resin composition according to claim 10.