WO2025070486A1 - Modified conjugated diene polymer and production method therefor, rubber bale, polymer composition, crosslinked product, and tire - Google Patents

Abstract

A modified conjugated diene polymer having a partial structure derived from a compound (M), which has a nitrogen atom and a hydrocarbyloxysilyl group in a single molecule, the modified conjugated diene polymer having a Mooney viscosity measured at 160°C of 80-150.

Description

Modified conjugated diene polymer and its manufacturing method, rubber veil, polymer composition, crosslinked product, and tire

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to Japanese Patent Application No. 2023-163701, filed on September 26, 2023, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a modified conjugated diene-based polymer and a method for producing the same, a rubber veil, a polymer composition, a crosslinked product, and a tire.

Conjugated diene polymers obtained by polymerization using conjugated diene compounds have excellent properties such as heat resistance, abrasion resistance, mechanical strength, and moldability, and are therefore widely used in various industrial products such as pneumatic tires, anti-vibration rubber, and hoses.

It is known that rubber compositions used in the treads and sidewalls of pneumatic tires are blended with fillers such as carbon black and silica together with conjugated diene polymers to improve the durability and abrasion resistance of the products. In addition, it has been proposed to use modified conjugated diene polymers in which heteroatoms such as silicon, nitrogen, oxygen, sulfur, and phosphorus have been introduced into the conjugated diene polymers in order to increase the affinity between the conjugated diene polymers and the fillers (see, for example, Patent Documents 1 to 3).

International Publication No. 2008/123164 Japanese Patent Application Publication No. 11-349632 International Publication No. 2017/221943

Amid the trend toward electrification and fuel efficiency in automobiles, rubber for automobile tires is required to have even lower rolling resistance, higher wear resistance and higher strength than ever before.

The present disclosure has been made in consideration of the above problems, and one of its objectives is to provide a modified conjugated diene polymer that can give a crosslinked product with a well-balanced improvement in rolling resistance, abrasion resistance, and strength.

In one embodiment, the present disclosure provides a modified conjugated diene polymer having a partial structure derived from a compound (M) having a nitrogen atom and a hydrocarbyloxysilyl group in one molecule, and having a Mooney viscosity of 80 or more and 150 or less measured at 160°C.

In another aspect, the present disclosure provides a method for producing the modified conjugated diene polymer, the method including the steps of: polymerizing the monomer in a solvent in the presence of a polymerization initiator by a continuous polymerization method to obtain a polymer having an active end; reacting the polymer having an active end with the compound (M) to obtain a polymer solution; and removing the solvent from the polymer solution without adding an extender oil to the polymer solution.

In another aspect, the present disclosure provides a rubber veil that contains the modified conjugated diene polymer and does not contain an extender oil.

In another aspect, the present disclosure provides a polymer composition comprising the modified conjugated diene-based polymer and at least one filler selected from the group consisting of silica, carbon black, and a compound represented by the following formula (1):
nM ¹・mSiO _k・iH ₂ O…(1)
(In formula (1), ^M1 is at least one selected from the group consisting of a specific metal, which is any one of aluminum, magnesium, titanium, zirconium, and calcium, an oxide of the specific metal, a hydroxide of the specific metal, and a carbonate of the specific metal. n is an integer of 1 to 5, m is an integer of 0 to 10, k is an integer of 2 to 5, and i is an integer of 0 to 10.)

According to another aspect of the present disclosure, a crosslinked body is provided in which the polymer composition is crosslinked. Also provided is a tire in which one or both of the tread and sidewall are made using the polymer composition.

The modified conjugated diene polymer disclosed herein can provide a crosslinked product with a good balance of improved rolling resistance, abrasion resistance, and strength.

　Below, matters related to the aspects of the present disclosure will be described in detail. Note that the present invention is not limited to the embodiments described below, and should be understood to include various modified examples that are implemented within the scope that does not change the gist of the present invention. In this specification, a numerical range described as "X to Y" represents a numerical range that includes numerical value X as the lower limit and numerical value Y as the upper limit.

The term "(meth)acrylic acid" is a concept that includes both "acrylic acid" and "methacrylic acid." "(Modified) conjugated diene polymer" is a term that includes unmodified conjugated diene polymers and modified conjugated diene polymers (i.e. modified conjugated diene polymers). In the following, when simply "conjugated diene polymer" is mentioned, the "conjugated diene polymer" may be an unmodified conjugated diene polymer or a modified conjugated diene polymer, unless otherwise specified that it is unmodified.

<Modified conjugated diene polymer>
The modified conjugated diene polymer of the present disclosure (hereinafter also referred to as "modified conjugated diene polymer (P)") has a structural unit derived from a conjugated diene compound and a partial structure derived from a compound having a nitrogen atom and a hydrocarbyloxysilyl group in one molecule (hereinafter also referred to as "compound (M)"). The modified conjugated diene polymer (P) has a Mooney viscosity measured at 160°C of 80 or more and 150 or less.

<Conjugated diene compound>
Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, and 2-chloro-1,3-butadiene. Among these, 1,3-butadiene, isoprene, and 2,3-dimethyl-1,3-butadiene are preferred. As the conjugated diene compound, one type may be used alone, or two or more types may be used in combination.

The modified conjugated diene polymer (P) may be a homopolymer of a conjugated diene compound, or may be a copolymer of a conjugated diene compound and a monomer different from the conjugated diene compound (hereinafter also referred to as "other monomer"). From the viewpoint of increasing the strength of the crosslinked body (i.e., rubber) obtained by using the modified conjugated diene polymer (P), it is preferable that the modified conjugated diene polymer (P) is a copolymer of a conjugated diene compound and an aromatic vinyl compound.

<Aromatic vinyl compounds>
Examples of aromatic vinyl compounds include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, t-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethylether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, vinylnaphthalene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene (e.g., 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene). Among these, the aromatic vinyl compound is preferably styrene or α-methylstyrene. The aromatic vinyl compounds may be used alone or in combination of two or more.

When the modified conjugated diene polymer (P) is a copolymer of a conjugated diene compound and an aromatic vinyl compound, it is preferable that the copolymer contains 1,3-butadiene and styrene in the monomer composition, since it has high living properties in anionic polymerization. In order to improve the hysteresis loss at low and high temperatures in a well-balanced manner, the modified conjugated diene polymer (P) preferably has a random copolymerization portion in which the distribution of the conjugated diene compound and the aromatic vinyl compound is irregular. The modified conjugated diene polymer (P) may further have a block portion made of a conjugated diene compound or an aromatic vinyl compound.

Other monomers include aromatic vinyl compounds, as well as acrylonitrile, methyl (meth)acrylate, ethyl (meth)acrylate, etc.

<Molecular structure>
The molecular structure of the modified conjugated diene polymer is not particularly limited, and may be linear or branched. In addition, in the modified conjugated diene polymer (P), the position of introduction of the partial structure derived from the compound (M) is also not particularly limited. For example, the modified conjugated diene polymer (P) may have the partial structure derived from the compound (M) at one end or both ends of the polymer, or may have it in a side chain. In addition, the modified conjugated diene polymer (P) may have a plurality of polymer chains and a partial structure derived from the compound (M), and may be a polymer in which one end of each of the plurality of polymer chains is bonded to the partial structure derived from the compound (M). In terms of being able to easily introduce the partial structure derived from the compound (M) into the polymer and having a high effect of improving rolling resistance, it is preferable that the modified conjugated diene polymer (P) has a structure in which a plurality of polymer chains and a partial structure derived from the compound (M) are bonded to the partial structure derived from the compound (M).

<Compound (M)>
The compound (M) may have a nitrogen atom and a hydrocarbyloxysilyl group in one molecule. In this specification, the term "hydrocarbyloxysilyl group" refers to a monovalent or divalent group in which 1 to 3 hydrocarbyloxy groups are bonded to a silicon atom. That is, the hydrocarbyloxysilyl group can be represented by "-Si(OR ²¹ ) _3-w (R ²⁰ ) _w " or ">Si(OR ²¹ ) _2-y (R ²⁰ ) _y " (wherein R ²⁰ and R ²¹ are each independently a hydrocarbyl group, w is an integer of 0 to 2, and y is 0 or 1). For example, a compound having two monovalent groups represented by "-Si(OR ²¹ ) ₃ " in one molecule and having a nitrogen-containing group is a "compound having a nitrogen-containing group and two hydrocarbyloxysilyl groups". The expression "having two or more hydrocarbyloxysilyl groups" does not represent the number of hydrocarbyloxy groups bonded to a silicon atom.

In the group represented by "-Si(OR ²¹ ) _3-w (R ²⁰ ) _w " or the group represented by ">Si(OR ²¹ ) _2-y (R ²⁰ ) _y ", examples of the hydrocarbyl group represented by R ²⁰ or R ²¹ include an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. R ²⁰ or R ²¹ is preferably a linear or branched alkyl group having 1 to 20 carbon atoms, more preferably a linear or branched alkyl group having 1 to 12 carbon atoms.

Compound (M) is preferably a modifying agent, specifically, an initiating end modifying agent for introducing a partial structure containing a heteroatom into the initiating end of a polymer, or a terminating end modifying agent for introducing a partial structure containing a heteroatom into the terminating end of a polymer. Herein, "modification" refers to imparting a partial structure containing a heteroatom such as nitrogen, oxygen, sulfur, phosphorus, or silicon to an unmodified conjugated diene polymer consisting of structural units derived from hydrocarbons. Hereinafter, compound (M) as an initiating end modifying agent is referred to as "compound (M1)," and compound (M) as a terminating end modifying agent is referred to as "compound (M2)."

(Compound (M1))
As the compound (M1), a compound having one or more of a secondary amino group and a tertiary amino group and one or more hydrocarbyloxysilyl groups can be preferably used. In the polymerization step for obtaining the modified conjugated diene polymer (P), when a metal compound such as an alkali metal compound or an alkaline earth metal compound is used as a polymerization initiator, if the compound (M1) has a secondary amino group, the active hydrogen of the secondary amino group becomes a reaction site with the metal compound, and the active hydrogen is replaced by a metal element, so that a metal amide compound can be efficiently produced. By polymerizing a monomer in the presence of the metal amide compound thus produced, a partial structure derived from the compound (M1) can be introduced into the polymerization initiation terminal. From the viewpoint of efficiently producing a metal amide compound by mixing the compound (M1) with a metal compound, the secondary amino group of the compound (M1) preferably constitutes a part of a ring skeleton, and more preferably constitutes a part of a nitrogen-containing aliphatic ring.

When the compound (M1) does not have a secondary amino group, it is preferable that the compound (M1) has, together with the tertiary amino group, a halogenated alkyl group having 1 to 8 carbon atoms, a monovalent cyclic group having a structure in which a halogen atom or a methyl group is bonded to an aromatic ring (hereinafter, also referred to as "cyclic group R ^C "), or both of them. When the compound (M1) has at least one of a halogenated alkyl group and a cyclic group R ^C , when a metal compound is used as a polymerization initiator, a halogen element or active hydrogen becomes a reaction site with the metal compound, and a halogen atom or active hydrogen is replaced by a metal element, thereby efficiently generating a carbon anion. By polymerizing a monomer in the presence of the carbon anion thus generated, a partial structure derived from the compound (M1) can be easily introduced to the polymerization initiation terminal. The compound (M1) may have, together with the secondary amino group, one or both of a halogenated alkyl group having 1 to 8 carbon atoms and a cyclic group R ^C.

（式（３）中、Ｘ^１は、下記式（４－１）又は式（４－２）で表される基である。Ａ^１は、炭素数１～２０の（ｉ＋ｋ）価の炭化水素基であるか、又は、窒素及び酸素の一方若しくは両方の原子を有し、活性水素を有さず、かつ基「－Ｓｉ（Ｒ^１）_ｎ（Ｙ^１）_３－ｎ」及び下記式（４－２）で表される基のそれぞれに対し炭素原子で結合する炭素数１～２０の（ｉ＋ｋ）価の基である。Ｒ^１は炭素数１～２０のヒドロカルビル基である。Ｙ^１は基「－ＯＲ^２」である。Ｒ^２は炭素数１～２０のヒドロカルビル基である。ｎは０～２の整数である。ｎが０又は１の場合、複数のＹ^１は同一又は異なる。ｎが２の場合、複数のＲ^１は同一又は異なる。ｉ及びｋは、互いに独立して１～６の整数である。ただし、ｉ＋ｋ≦１０を満たす。式中、Ｘ^１が複数ある場合、複数のＸ^１は同一又は異なる。基「－Ｓｉ（Ｒ^１）_ｎ（Ｙ^１）_３－ｎ」が複数ある場合、複数の基「－Ｓｉ（Ｒ^１）_ｎ（Ｙ^１）_３－ｎ」は同一又は異なる。）

（式（４－１）中、Ｒ^５は、水素原子、炭素数１～８のハロゲン化アルキル基、又は、芳香環にハロゲン原子若しくはメチル基が結合した構造を有する１価の環状基である。Ｒ^６及びＲ^７は、互いに独立して炭素数１～１０のヒドロカルビレン基である。Ｑ^１及びＱ^２は、互いに独立して窒素原子又は－ＣＲ^１０－である。ただし、Ｒ^５が水素原子の場合、Ｑ^１は窒素原子である。Ｒ^１０は水素原子又は炭素数１～２０のヒドロカルビル基である。「＊」は結合手を表す。
　式（４－２）中、Ｒ^８は、水素原子、炭素数１～８のハロゲン化アルキル基、又は、芳香環にハロゲン原子若しくはメチル基が結合した構造を有する１価の環状基（環状基Ｒ^Ｃ）である。Ｒ^９は、炭素数１～２０のヒドロカルビル基又はトリヒドロカルビルシリル基である。ただし、Ｒ^８が水素原子の場合、Ｒ^９は炭素数１～２０のヒドロカルビル基である。「＊」は結合手を表す。） A preferred specific example of the compound (M1) is a compound represented by the following formula (3).

(In formula (3), X ¹ is a group represented by formula (4-1) or formula (4-2) below. ^{A 1} is a (i+k)-valent hydrocarbon group having 1 to 20 carbon atoms, or a (i+k)-valent group having 1 to 20 carbon atoms which has one or both of nitrogen and oxygen atoms, has no active hydrogen, and is bonded via a carbon atom to the group "-Si(R ¹ ) _n (Y ¹ ) _3-n " and the group represented by formula (4-2) below. R ¹ is a hydrocarbyl group having 1 to 20 carbon atoms. Y ¹ is a group "-OR ² ". R ² is a hydrocarbyl group having 1 to 20 carbon atoms. n is an integer of 0 to 2. When n is 0 or 1, multiple Y ^1s are the same or different. When n is 2, multiple R ¹ are the same or different. i and k are each independently an integer of 1 to 6, provided that i+k≦10 is satisfied. In the formula, when there are a plurality of X ^1's , the plurality of X ^1's are the same or different. When there are a plurality of groups "-Si(R ¹ ) _n (Y ¹ ) _3-n ", the plurality of groups "-Si(R ¹ ) _n (Y ¹ ) _3-n " are the same or different.

(In formula (4-1), R ⁵ is a hydrogen atom, a halogenated alkyl group having 1 to 8 carbon atoms, or a monovalent cyclic group having a structure in which a halogen atom or a methyl group is bonded to an aromatic ring. ^{R 6} and R ⁷ are each independently a hydrocarbylene group having 1 to 10 carbon atoms. Q ¹ and Q ² are each independently a nitrogen atom or -CR ¹⁰ -, provided that when R ⁵ is a hydrogen atom, Q ¹ is a nitrogen atom. R ¹⁰ is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms. "*" represents a bond.
In formula (4-2), R ⁸ is a hydrogen atom, a halogenated alkyl group having 1 to 8 carbon atoms, or a monovalent cyclic group (cyclic group R ^C ) having a structure in which a halogen atom or a methyl group is bonded to an aromatic ring. R ⁹ is a hydrocarbyl group or trihydrocarbylsilyl group having 1 to 20 carbon atoms. However, when R ⁸ is a hydrogen atom, R ⁹ is a hydrocarbyl group having 1 to 20 carbon atoms. "*" represents a bond.)

In formula (3), when X ¹ is a group represented by formula (4-1), from the viewpoint of obtaining a crosslinked body having superior rolling resistance, X ¹ preferably has a nitrogen-containing heterocycle, more preferably has a nitrogen-containing heterocycle containing a tertiary nitrogen atom. The hydrocarbylene group having 1 to 10 carbon atoms represented by R ⁶ and R ⁷ is preferably a linear or branched alkanediyl group having 1 to 20 carbon atoms, more preferably a methylene group or an ethylene group.

When the groups represented by ^Q1 and ^Q2 are ^-CR10- , the hydrocarbyl group having 1 to 20 carbon atoms represented by ^R10 is preferably a linear or branched alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. Among these, ^R10 is preferably a hydrogen atom or a methyl group.
From the viewpoint of improving the rolling resistance of the obtained crosslinked body, ^Q1 and ^Q2 are preferably nitrogen atoms. Among them, it is particularly preferable that ^Q2 of ^Q1 and ^Q2 is a tertiary nitrogen atom, or that ^Q1 and ^Q2 are both tertiary nitrogen atoms.

Examples of halogenated alkyl groups having 1 to 8 carbon atoms represented by ^R5 and ^R8 include groups in which any hydrogen atom in an alkyl group having 1 to 8 carbon atoms is substituted with a halogen atom. The alkyl group having 1 to 8 carbon atoms substituted with a halogen atom may be linear or branched. The alkyl group is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. Examples of halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom or a bromine atom is preferred.

When the group represented by ^R5 and ^R8 is a cyclic group ^R3C , examples of the aromatic ring contained in the cyclic group ^R3C include a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring or a naphthalene ring is preferable. In the cyclic group ^R3C , the aromatic ring may further have a substituent other than a halogen atom and a methyl group. Examples of the substituent include an N,N-dialkylamino group. Examples of the halogen atom bonded to the aromatic ring include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom or a bromine atom is preferable, and a bromine atom is more preferable.

Specific examples of the groups represented by ^R5 and ^R8 when they are cyclic groups ^R3C include a 2-methylphenyl group, a 3-methylphenyl group, a 4-methylphenyl group, a 2-bromophenyl group, a 3-bromophenyl group, a 4-bromophenyl group, a 2-N,N-dimethylamino-3-methylphenyl group, a 2-N,N-dimethylamino-4-methylphenyl group, a 2-N,N-dimethylamino-5-methylphenyl group, a 2-methyl-3-N,N-dimethylaminophenyl group, a 3-N,N-dimethylamino-4-methylphenyl group, a 3-N,N-dimethylamino-4-methylphenyl group, Examples of the alkyl group include an -N,N-dimethylamino-5-methylphenyl group, a 2-N,N-dimethylamino-3-bromophenyl group, a 2-N,N-dimethylamino-4-bromophenyl group, a 2-N,N-dimethylamino-5-bromophenyl group, a 2-bromo-3-N,N-dimethylaminophenyl group, a 3-N,N-dimethylamino-4-bromophenyl group, a 3-N,N-dimethylamino-5-bromophenyl group, a 5-bromonaphthalenyl group, and a 5-bromoanthracenyl group.

From the viewpoint of reactivity with metal compounds, R ⁵ is preferably a hydrogen atom, a cyclic group R 3 ^C , or a halogenated alkyl group having 1 to 8 carbon atoms, and more preferably a hydrogen atom, a monovalent cyclic group having a structure in which a bromine atom is bonded to an aromatic ring, a bromoalkyl group having 1 to 8 carbon atoms, or a chloroalkyl group having 1 to 8 carbon atoms. R ⁸ is preferably a cyclic group R 3 ^C , or a halogenated alkyl group having 1 to 8 carbon atoms, and more preferably a monovalent cyclic group having a structure in which a bromine atom is bonded to an aromatic ring, a bromoalkyl group having 1 to 8 carbon atoms, or a chloroalkyl group having 1 to 8 carbon atoms.

The hydrocarbyl group having 1 to 20 carbon atoms represented by ^R9 is preferably an alkyl group having 1 to 20 carbon atoms, more preferably a linear or branched alkyl group having 1 to 20 carbon atoms. Examples of the trihydrocarbylsilyl group include a trimethylsilyl group and a triethylsilyl group.
From the viewpoint of increasing the reactivity of X ¹ with the metal compound, X ¹ is preferably a group represented by formula (4-1).

Examples of ^A1 that is a (i+k)-valent hydrocarbyl group include groups in which (i+k) hydrogen atoms have been removed from a chain hydrocarbon having 1 to 20 carbon atoms, an alicyclic hydrocarbon having 3 to 20 carbon atoms, or an aromatic hydrocarbon having 6 to 20 carbon atoms. Among these, groups in which (i+k) hydrogen atoms have been removed from a chain hydrocarbon are preferred.

Specific examples of A ¹ which is an (i+k)-valent group having 1 to 20 carbon atoms, containing one or both of nitrogen and oxygen atoms and no active hydrogen include an (i+k)-valent heterocyclic group, an (i+k)-valent group having a tertiary amine structure, etc. The heterocyclic group is preferably a conjugated system, and examples thereof include a monocyclic or condensed ring such as pyridine, pyrimidine, pyrazine, quinoline, naphthalidine, furan, etc., or a group in which (i+k) hydrogen atoms have been removed from the ring portion of a structure in which a plurality of such monocyclic or condensed rings are linked together.

(i+k) is an integer of from 2 to 10. (i+k) is preferably an integer of from 2 to 6 from the viewpoint of processability of the polymer composition.
Examples of the hydrocarbyl group having 1 to 20 carbon atoms represented by ^R1 and ^R2 include an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. ^R1 and ^R2 are preferably a linear or branched alkyl group having 1 to 20 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 12 carbon atoms.
A ¹ is bonded to the group "-Si(R ¹ ) _n (Y ¹ ) _3-n " and the group represented by the above formula (4-2) via a carbon atom, and more specifically, it is preferable that A 1 is bonded to the group "-Si(R 1 ) n (Y 1 ) 3-n " and the group represented by the above formula (4-2) via the same or different carbon atoms constituting the hydrocarbon group.

Specific examples of the compound (M1) include compounds represented by the following formulas (M1-1) to (M1-50). As the compound (M1), one type may be used alone, or two or more types may be used in combination.

(Compound (M2))
Compound (M2) is not particularly limited as long as it is a compound having one or more nitrogen atoms and one or more hydrocarbyloxysilyl groups. When a conjugated diene polymer having an active end (more specifically, a metal end) is obtained in the polymerization step for obtaining modified conjugated diene polymer (P), and then the conjugated diene polymer having an active end is reacted with compound (M2), the hydrocarbyloxysilyl group becomes a reaction site with the active end of the conjugated diene polymer, and a partial structure derived from compound (M2) can be introduced into the termination end of the polymer. The molecular weight of compound (M2) is preferably 1,000 or less, more preferably 800 or less.

The number of reactive sites with the active end of the polymer in the compound (M2) may be only one or may be two or more. For example, when the number of reactive sites with the active end of the polymer in the compound (M2) is one, a modified conjugated diene polymer (P) having a partial structure derived from the compound (M2) at one end can be obtained as the modified conjugated diene polymer (P). When the number of reactive sites with the active end of the polymer in the compound (M2) is two or more, a polymer having a structure in which each end of a plurality of polymer chains is bonded to a partial structure derived from the compound (M2) can be obtained as the modified conjugated diene polymer (P). In terms of being able to achieve a good balance of strength, abrasion resistance, and rolling resistance, the number of reactive sites with the active end in the compound (M2) is preferably two or more, more preferably two to six, and even more preferably two to four.

（式（４）中、Ａ^３は、窒素、リン、酸素及びケイ素よりなる群から選択される少なくとも一種の原子を有し、活性水素を有さず、かつＲ^２２に対して窒素、リン、酸素若しくはケイ素で結合する１価の官能基であるか、又は炭素数１～２０のヒドロカルビル基である。Ｒ^２２は単結合又はヒドロカルビレン基であり、Ｒ^２３及びＲ^２４は、それぞれ独立してヒドロカルビル基であり、Ｒ^２５はヒドロカルビレン基であり、ｔは０又は１である。ただし、ｔが０の場合、式中の複数のＲ^２４は同一又は異なる。）

（式（５）中、Ｒ^３１は、炭素数１～２０のヒドロカルビレン基であり、Ｒ^３２及びＲ^３３は、互いに独立して炭素数１～２０のヒドロカルビル基であり、Ａ^４は、基「＊－Ｃ（Ｒ^３５）＝Ｎ－」又は基「＊－Ｎ＝Ｃ（Ｒ^３５）－」（ただし、Ｒ^３５は水素原子又はヒドロカルビル基であり、「＊」はＲ^３４に結合する結合手を表す。）である。Ｒ^３４は、炭素数１～２０のｍ価の炭化水素基、又は、窒素及び酸素の一方又は両方の原子を有し、かつ活性水素を有さない炭素数１～２０のｍ価の基である。ｎは１～３の整数であり、ｍは２～１０の整数である。Ｒ^３１～Ｒ^３３及びＡ^１の各記号につき、同一の記号が式中に複数個存在する場合、その記号が表す基は、互いに同一又は異なる。式中の複数のｎは同一又は異なる。）

（式（６）中、Ｒ^４２、Ｒ^４３及びＲ^４５は、互いに独立して炭素数１～１２のアルカンジイル基であり、Ｒ^４０、Ｒ^４１、Ｒ^４８及びＲ^４９は、互いに独立して炭素数１～２０のヒドロカルビル基である。Ａ^２は、含窒素複素環基又は下記式（ａ－２）

（式（ａ－２）中、Ｒ^４６及びＲ^４７は、互いに独立して炭素数１～２０のヒドロカルビル基である。ａは１～３の整数である。各記号につき、同一の記号が式中に複数個存在する場合、その記号が表す基は、互いに同一又は異なる。「＊」は結合手を表す。）
で表される基である。ｃ及びｄは、互いに独立して１～３の整数であり、ｂは１～１０の整数である。各記号につき、同一の記号が式中に複数個存在する場合、その記号が表す基は、互いに同一又は異なる。） A preferred specific example of the compound (M2) is at least one selected from the group consisting of a compound represented by the following formula (4), a compound represented by the following formula (5), and a compound represented by the following formula (6).

(In formula (4), ^A3 is a monovalent functional group having at least one atom selected from the group consisting of nitrogen, phosphorus, oxygen, and silicon, having no active hydrogen, and bonded to ^R22 via nitrogen, phosphorus, oxygen, or silicon, or a hydrocarbyl group having 1 to 20 carbon atoms. ^R22 is a single bond or a hydrocarbylene group, ^R23 and ^R24 are each independently a hydrocarbyl group, ^R25 is a hydrocarbylene group, and t is 0 or 1. However, when t is 0, multiple ^R24s in the formula are the same or different.)

(In formula (5), R ³¹ is a hydrocarbylene group having 1 to 20 carbon atoms, R ³² and R ³³ are each independently a hydrocarbyl group having 1 to 20 carbon atoms, and A ⁴ is a group "*-C(R ³⁵ )=N-" or a group "*-N=C(R ³⁵ )-" (wherein R ³⁵ is a hydrogen atom or a hydrocarbyl group, and "*" represents a bond bonded to R ³⁴ ). R ³⁴ is an m-valent hydrocarbon group having 1 to 20 carbon atoms, or an m-valent group having 1 to 20 carbon atoms having one or both of nitrogen and oxygen atoms and no active hydrogen. n is an integer of 1 to 3, and m is an integer of 2 to 10. When the same symbol is present multiple times in the formula for each of R ³¹ to R ³³ and A ¹ , the groups represented by the symbol are the same or different from each other. Multiple n's in the formula are the same or different.)

In formula (6), R ⁴² , R ⁴³ and R ⁴⁵ are each independently an alkanediyl group having 1 to 12 carbon atoms, and R ⁴⁰ , R ⁴¹ , R ⁴⁸ and R ⁴⁹ are each independently a hydrocarbyl group having 1 to 20 carbon atoms. A ² is a nitrogen-containing heterocyclic group or a group represented by the following formula (a-2):

(In formula (a-2), R ⁴⁶ and R ⁴⁷ are each independently a hydrocarbyl group having 1 to 20 carbon atoms. a is an integer of 1 to 3. When the same symbol is present multiple times in the formula, the groups represented by the symbols are the same or different. "*" represents a bond.)
c and d are each independently an integer of 1 to 3, and b is an integer of 1 to 10. When the same symbol is present multiple times in the formula, the groups represented by the symbols are the same or different.

In the above formula (4), the hydrocarbyl groups represented by R ²³ and R ²⁴ are preferably a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. ^{R 22} is preferably a linear or branched alkanediyl group having 1 to 20 carbon atoms, a cycloalkylene group having 3 to 20 carbon atoms, or an arylene group having 6 to 20 carbon atoms. R ²⁵ is preferably a linear or branched alkanediyl group having 1 to 20 carbon atoms.

At least one atom selected from the group consisting of nitrogen, phosphorus, oxygen and silicon contained in ^A3 is not bonded to active hydrogen and may be protected by a protecting group (e.g., a tri-substituted hydrocarbylsilyl group, etc.). ^A3 may be a group that can become an onium ion by the action of an onium salt generating agent.

Specific examples of ^A3 include a nitrogen-containing group in which two hydrogen atoms of a primary amino group are replaced by two protective groups, a nitrogen-containing group in which one hydrogen atom of a secondary amino group is replaced by one protective group, a tertiary amino group, an imino group, a pyridyl group, a phosphorus-containing group in which two hydrogen atoms of a primary phosphino group are replaced by two protective groups, a phosphorus-containing group in which one hydrogen atom of a secondary phosphino group is replaced by one protective group, a tertiary phosphino group, a group in which the hydrogen atom of a hydroxyl group is protected by a protective group, a hydrocarbyloxysilyl group, etc. Among these, ^A3 is preferably a group having silicon or nitrogen, and more preferably a hydrocarbyloxysilyl group, a nitrogen-containing group having a protective group, or a tertiary amino group. Examples of the hydrocarbyloxysilyl group include a trimethoxysilyl group, a methyldimethoxysilyl group, a dimethylmethoxysilyl group, and groups in which the methyl group in these groups is replaced by an alkyl group or an alkenyl group having 2 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

In the above formula (5), examples of the hydrocarbylene group for R ³¹ include an alkanediyl group having 1 to 12 carbon atoms, a cycloalkylene group having 3 to 12 carbon atoms, and an arylene group having 6 to 12 carbon atoms. Examples of the hydrocarbyl group for ^{R 32} and R ³³ include an alkyl group having 1 to 20 carbon atoms, an allyl group, a cycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

The m-valent hydrocarbon group of R ³⁴ is a group in which m hydrogen atoms have been removed from a hydrocarbon. Of these, the m-valent hydrocarbon group of R ³⁴ is preferably a group in which m hydrogen atoms have been removed from the ring portion of an aromatic hydrocarbon (an m-valent aromatic ring group). Specific examples of aromatic hydrocarbons include single rings or condensed rings such as a benzene ring, a naphthalene ring, an anthracene ring, and the like, and structures in which two or more of these rings are bonded together by a single bond.

When R ³⁴ is an m-valent group having 1 to 20 carbon atoms, which has one or both of a nitrogen atom and an oxygen atom and has no active hydrogen, specific examples thereof include an m-valent heterocyclic group, an m-valent group having a tertiary amine structure, etc. The heterocyclic group is preferably a conjugated system, and examples thereof include a single ring or a condensed ring such as pyridine, pyrimidine, pyrazine, quinoline, naphthalidine, furan, etc., or a group in which m hydrogen atoms have been removed from the ring portion of a structure in which a plurality of these rings are linked together.

From the viewpoint of improving the processability of the polymer composition, m is preferably 2 to 6. n is preferably 2 or 3, and more preferably 3, from the viewpoint of enhancing the effect of improving silica dispersibility.

In the above formula (6) and formula (a-2), the alkanediyl groups of R ⁴⁵ , R ⁴² and R ⁴³ are preferably linear. Examples of the hydrocarbyl groups of ^{R 40} , R ⁴¹ , and R ⁴⁶ to R ⁴⁹ include an alkyl group having 1 to 20 carbon atoms, an allyl group, a cycloalkyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms. The nitrogen-containing heterocyclic group represented by A ² is preferably a group derived from a conjugated heterocycle, and examples thereof include groups in which one hydrogen atom has been removed from a nitrogen-containing heterocycle such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, quinoline, naphthalidine, or benzimidazole.

For a, c, and d, 2 or 3 is preferred, and 3 is more preferred, as they have a high effect of improving the dispersibility of the filler (especially silica). For b, 1 to 5 is preferred, and 1 to 3 is more preferred.

Specific examples of compound (M2) include compounds represented by the above formula (4), such as 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane, 1-triethylsilyl-2,2-diethoxy-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1,2-azasilolidine, 2,2-dimethoxy-1-phenyl-1,2-azasilolidine, 2-(2,2-dimethoxy-1,2-azasilolidine-1-yl)-N,N-diethylethane-1-amine, and compounds in which the alkyl groups and alkanediyl groups in these compounds are replaced with alkyl groups having 1 to 6 carbon atoms and alkanediyl groups having 1 to 6 carbon atoms, respectively.

のそれぞれで表される化合物、及び当該化合物中のアルキル基、アルカンジイル基をそれぞれ、炭素数１～６のアルキル基、炭素数１～６のアルカンジイル基に置き換えた化合物等を挙げることができる。 Examples of the compound represented by formula (5) include compounds represented by the following formulae (M2-1-1) to (M2-1-7):

and compounds in which the alkyl group and alkanediyl group in the above compounds are replaced by an alkyl group having 1 to 6 carbon atoms and an alkanediyl group having 1 to 6 carbon atoms, respectively.

Examples of the compound represented by the above formula (6) include tris(2-triethoxysilylethyl)amine, tris(3-triethoxysilylpropyl)amine, tris(5-triethoxysilylpentyl)amine, N,N,N',N'-tetra(2-triethoxysilylethyl)-1,2-diaminoethane, N,N,N',N'-tetra(3-triethoxysilylpropyl)-1,3-diaminopropane, N-(3-(1H-imidazole-1- Examples of the end-modifying agent include N-(3-(1H-imidazol-1-yl)propyl)-3-(trimethoxysilyl)-N-(3-(trimethoxysilyl))propyl)propan-1-amine, N-(3-(1H-imidazol-1-yl)propyl)-N,N-bis(3-(trimethoxysilyl))propyl)propanamine, and compounds in which the alkyl group and alkanediyl group in these compounds are replaced with an alkyl group having 1 to 6 carbon atoms and an alkanediyl group having 1 to 6 carbon atoms, respectively. One type of end-modifying agent may be used alone, or two or more types may be used in combination.

In the crosslinked body obtained using the modified conjugated diene polymer (P), it is preferable that the modified conjugated diene polymer (P) has a partial structure derived from the compound (M2), in that it is possible to improve rolling resistance and strength in a well-balanced manner. When the modified conjugated diene polymer (P) has a partial structure derived from the compound (M2), the modified conjugated diene polymer (P) may further have a partial structure derived from the compound (M1) in addition to the partial structure derived from the compound (M2). In addition, it is preferable to use at least a compound having two or more hydrocarbyloxysilyl groups as the compound (M), in that it is possible to obtain a crosslinked body having improved rolling resistance, strength, and abrasion resistance in a well-balanced manner.

<Physical Properties of Modified Conjugated Diene Polymer (P)>
Next, the physical properties of the modified conjugated diene polymer (P) will be described.

(Mooney Viscosity)
The modified conjugated diene polymer (P) has a Mooney viscosity measured at 160°C of 80 or more and 150 or less. If the Mooney viscosity measured at 160°C of the modified conjugated diene polymer is less than 80, the strength, abrasion resistance and rolling resistance of the crosslinked body obtained using the modified conjugated diene polymer tend not to be improved in a well-balanced manner. If the Mooney viscosity measured at 160°C of the modified conjugated diene polymer is higher than 150, the processability of the modified conjugated diene polymer is poor. From the above viewpoint, the Mooney viscosity measured at 160°C of the modified conjugated diene polymer (P) is preferably 90 or more, more preferably 95 or more, and even more preferably 100 or more. If the Mooney viscosity measured at 160°C of the modified conjugated diene polymer is 140 or less.

The Mooney viscosity of the modified conjugated diene polymer (P) at 160°C is a value measured under the conditions described in JIS K6300-1, except that the measurement temperature is 160°C. The Mooney viscosity of the modified conjugated diene polymer (P) can be adjusted to be within the above range by controlling the weight average molecular weight and molecular weight distribution (= weight average molecular weight/number average molecular weight), the presence or absence of branching and the number of branches, the molar ratio of the terminal modifier to the polymerization initiator, the polymerization temperature, etc. of the modified conjugated diene polymer (P). The Mooney viscosity of the modified conjugated diene polymer (P) may also be adjusted to be within the above range by the amount of extender oil added.

(Vinyl group content)
The vinyl group content of the modified conjugated diene polymer (P) is preferably 10 to 70% by mass. When the vinyl group content is 10% by mass or more, the grip property can be improved, and when it is 70% by mass or less, it is preferable in that the deterioration of the abrasion resistance of the obtained vulcanized rubber can be suppressed. The vinyl group content is more preferably 12% by mass or more, and even more preferably 15% by mass or more. Moreover, the vinyl group content is more preferably 60% by mass or less, even more preferably 50% by mass or less, even more preferably 45% by mass or less, and particularly preferably 30% by mass or less. In this specification, the "vinyl group content" is a value indicating the content ratio of structural units having 1,2-bonds to all structural units of butadiene in the conjugated diene polymer, and is a value measured by ¹ H-NMR.

(Content of structural units derived from aromatic vinyl compounds)
In the modified conjugated diene polymer (P), the content of the structural unit derived from an aromatic vinyl compound is preferably 3 to 55 mass% based on the total amount of the structural units possessed by the modified conjugated diene polymer (P) from the viewpoint of achieving a good balance between the rolling resistance and the wet skid resistance of the crosslinked body obtained. The content of the structural unit derived from an aromatic vinyl compound is more preferably 5 mass% or more, and even more preferably 10 mass% or more. The content of the structural unit derived from an aromatic vinyl compound is more preferably 45 mass% or less, even more preferably 40 mass% or less, even more preferably 35 mass% or less, and even more preferably 30 mass% or less. The content of the structural unit derived from an aromatic vinyl compound in the conjugated diene polymer is a value measured by ¹ H-NMR.

(Weight average molecular weight)
The weight average molecular weight (Mw) of the modified conjugated diene polymer (P) in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 7.0×10 ⁵ or more and 3.0×10 ⁶ or less. When the Mw of the modified conjugated diene polymer (P) is 7.0×10 ⁵ or more, a crosslinked body having higher strength, excellent wear resistance, and sufficiently small rolling resistance can be obtained. When the Mw of the modified conjugated diene polymer (P) is 3.0×10 ⁶ or less, the processability of the polymer composition containing the modified conjugated diene polymer (P) can be improved. From the viewpoint of further enhancing the effect of improving the strength, wear resistance, and rolling resistance, the Mw of the modified conjugated diene polymer (P) is more preferably 7.2×10 ⁵ or more, and even more preferably 7.5×10 ⁵ or more. From the viewpoint of processability, the Mw of the modified conjugated diene polymer (P) is more preferably 2.5 × 10 ⁶ or less, and even more preferably 2.0 × 10 ⁶ or less. The weight average molecular weight (Mw) of the modified conjugated diene polymer represents the weight average molecular weight (total weight average molecular weight) based on all peaks of a GPC curve measured by GPC.

(Molecular Weight Distribution)
The molecular weight distribution (Mw/Mn) of the modified conjugated diene polymer (P), which is expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured using GPC, is preferably 1.60 or more and 4.00 or less from the viewpoint of productivity, etc. The molecular weight distribution (Mw/Mn) of the modified conjugated diene polymer (P) is more preferably 3.00 or less, and even more preferably 2.50 or less. The molecular weight distribution (Mw/Mn) of the modified conjugated diene polymer (P) is more preferably 1.70 or more, and even more preferably 1.80 or more.

(Glass Transition Temperature)
The modified conjugated diene polymer (P) preferably has an endothermic peak in the temperature range of -100°C to 20°C in differential scanning calorimetry (DSC) in accordance with JIS K6240:2011. The inflection point of the DSC curve obtained by DSC analysis, i.e., the peak top temperature of the differential curve, is the measured value of the glass transition temperature of the modified conjugated diene polymer (P). In other words, the modified conjugated diene polymer (P) preferably has a glass transition temperature of -100°C to 20°C.

The glass transition temperature of the modified conjugated diene polymer (P) is more preferably -90°C or higher, and even more preferably -80°C or higher. From the viewpoint of improving wet grip performance, the glass transition temperature of the modified conjugated diene polymer (P) is more preferably -20°C or lower, even more preferably -40°C or lower, even more preferably -50°C or lower, and particularly preferably -55°C or lower. In particular, when the modified conjugated diene polymer (P) has only one endothermic peak in DSC analysis and the peak temperature of the endothermic peak is in the temperature range of -100°C to 20°C, the crosslinked body formed using the modified conjugated diene polymer (P) tends to have good abrasion resistance and strength.

<Method for producing modified conjugated diene polymer>
The method for producing the modified conjugated diene polymer (P) is not particularly limited. The modified conjugated diene polymer (P) is preferably produced by a method including the following polymerization step and modification step.
Polymerization step: a step of polymerizing a monomer containing a conjugated diene compound in the presence of a polymerization initiator to obtain a conjugated diene polymer having an active end. Modification step: a step of reacting a conjugated diene polymer having an active end with a compound (M). Each step will be described in detail below.

<Polymerization step>
In the polymerization step, the polymerization method for polymerizing the monomer containing the conjugated diene compound is particularly preferably a solution polymerization method. The polymerization form may be either a batch type or a continuous type. When using the solution polymerization method, a specific example of the polymerization method is a method in which a monomer is polymerized in an organic solvent in the presence of a polymerization initiator and a vinyl group content regulator (randomizer) used as necessary. From the viewpoints of the processability of the polymer composition being good, the dispersibility of the filler (particularly silica) being high, the ability to obtain a high-strength crosslinked body, and the productivity of the polymer, it is preferable to use a continuous type (specifically, a method in which the raw material is continuously fed into a reactor and the product is continuously withdrawn from the reactor).

In a continuous polymerization system, the raw material supply rate may be constant or variable. In addition, as long as the polymerization reaction process includes a step of continuously supplying the raw materials to the reactor, it may further include a step of intermittently supplying the raw materials. Similarly, for the product withdrawal operation, in a continuous polymerization system, the product withdrawal rate may be constant or variable. In addition, as long as the polymerization reaction process includes a step of continuously removing the product from the reactor, it may further include a step of intermittently removing the product.

As the polymerization initiator, an alkali metal compound or an alkaline earth metal compound can be preferably used, and an alkali metal compound is more preferable. Specific examples of the polymerization initiator include alkyl lithium, 1,4-dilithiobutane, phenyl lithium, stilbene lithium, naphthyl lithium, 1,3-bis(1-lithio-1,3-dimethylpentyl)benzene, 1,3-phenylenebis(3-methyl-1-phenylpentylidene)dilithium, naphthyl sodium, naphthyl potassium, di-n-butyl magnesium, di-n-hexyl magnesium, ethoxy potassium, calcium stearate, etc. Specific examples of the alkyl lithium include methyl lithium, ethyl lithium, n-propyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, etc. The polymerization initiator is preferably a lithium compound. The ratio of the polymerization initiator used in the polymerization (the total amount when two or more types are used) is preferably 0.2 to 20 mmol per 100 g of monomer used in the polymerization.

The polymerization reaction may also be carried out in the presence of a metal amide compound obtained by mixing an alkali metal compound or an alkaline earth metal compound with an initiation end modifier. By polymerizing a monomer in the presence of a metal amide compound, a functional group derived from the initiation end modifier can be introduced into the polymerization initiation end of the conjugated diene polymer.

As the initiating end modifying agent, nitrogen-containing compounds such as secondary amine compounds can be preferably used. Specific examples of the initiating end modifying agent include, in addition to the above-mentioned compound (M1), chain amines such as dimethylamine, diethylamine, dipropylamine, dibutylamine, dodecamethyleneimine, N,N'-dimethyl-N'-trimethylsilyl-1,6-diaminohexane, di-(2-ethylhexyl)amine, and diallylamine; and cyclic amines such as piperidine, pyrrolidine, hexamethyleneimine, heptamethyleneimine, dicyclohexylamine, N-methylbenzylamine, morpholine, N-(trimethylsilyl)piperazine, N-(tert-butyldimethylsilyl)piperazine, and 1,3-ditrimethylsilyl-1,3,5-triazinane.

When polymerizing a monomer in the presence of a compound obtained by mixing an alkali metal compound or an alkaline earth metal compound with an initiating end modifier, at least one of an alkali metal compound and an alkaline earth metal compound may be mixed with the initiating end modifier in advance, and the mixture may be added to the polymerization system to carry out polymerization. Alternatively, at least one of an alkali metal compound and an alkaline earth metal compound with the initiating end modifier may be added to the polymerization system separately or simultaneously, and the two may be mixed in the polymerization system to carry out polymerization. Either of these cases is included in the embodiment of "polymerizing a monomer in the presence of a compound obtained by mixing an alkali metal compound or an alkaline earth metal compound with an initiating end modifier."

The amount of the initiating end modifier used is appropriately set depending on the type of alkali metal compound or alkaline earth metal compound. For example, when a lithium compound is used as the alkali metal compound or alkaline earth metal compound, from the viewpoint of obtaining a modified conjugated diene polymer (P) with a well-balanced improvement in processability and rolling resistance, the amount of the initiating end modifier used is preferably in the range of 0.1 to 1.8 mol, and more preferably in the range of 0.2 to 1.0 mol, per 1 mol of the total lithium metal used in the polymerization. As the initiating end modifier, one type can be used alone, or two or more types can be used in combination.

Vinyl group content regulators (randomizers) are used for the purpose of adjusting the vinyl group content, which indicates the content of vinyl bonds in modified conjugated diene polymers. Examples of randomizers include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-di(tetrahydrofuryl)propane, 2-(2-ethoxyethoxy)-2-methylpropane, triethylamine, pyridine, N-methylmorpholine, and tetramethylethylenediamine. Randomizers can be used alone or in combination of two or more.

The organic solvent used in the polymerization may be any organic solvent that is inert to the reaction. Examples of such organic solvents include linear or cyclic aliphatic hydrocarbons and aromatic hydrocarbons. The organic solvent used in the polymerization is preferably a hydrocarbon having 3 to 8 carbon atoms, and specific examples thereof include propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene, heptane, cyclopentane, methylcyclopentane, methylcyclohexane, 1-pentene, 2-pentene, cyclohexene, etc. As the organic solvent, one of these can be used alone or two or more can be used in combination.

When solution polymerization is used, the monomer concentration in the reaction solvent is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass, from the viewpoint of maintaining a balance between productivity and ease of polymerization control. When polymerization is performed using a continuous polymerization method, the supply speed of each component such as monomer is not particularly limited and can be set appropriately depending on the amount of each component added and the size of the reactor. The temperature of the polymerization reaction is preferably -20°C to 150°C, and more preferably 0 to 120°C. The polymerization reaction is preferably performed under a pressure sufficient to keep the monomer substantially in a liquid phase.

By such a polymerization reaction, a conjugated diene polymer having an active end (more specifically, an alkali metal active end or an alkaline earth metal active end) can be obtained. In this specification, the term "active end" refers to the portion (more specifically, the metal end) that is present at the end of the molecular chain and is not derived from the structure of the monomer having a carbon-carbon double bond.

<Modification step>
In the modification step, it is preferable to use a compound (M2) as a terminal modifier and react the active terminal of the conjugated diene polymer obtained by the polymerization step with the compound (M2). By reacting the conjugated diene polymer having an active terminal with the compound (M2), a polymer chain containing a monomer unit derived from a conjugated diene compound and the compound (M2) are bonded at a reaction site of the compound (M2), and a modified conjugated diene polymer (P) having one or more polymer chains in one molecule can be obtained. This makes it possible to make the rolling resistance of the crosslinked body obtained using the present composition excellent. The conjugated diene polymer having an active terminal that is reacted with the terminal modifier may have a modified or unmodified polymerization initiation terminal.

The reaction between the polymerization active terminals and the terminal modifier is preferably carried out as a solution reaction. This solution reaction may be carried out using a solution containing unreacted monomers after the polymerization reaction has been completed, or may be carried out after isolating the conjugated diene polymer having polymerization active terminals contained in the solution and dissolving it in an appropriate solvent such as cyclohexane. The reaction may be carried out either batchwise or continuously. From the viewpoint of productivity, etc., it is preferable to carry out the polymerization step and the modification step in a continuous manner.

The amount of the terminal modifying agent used in the above reaction may be appropriately set according to the type of compound used in the reaction. The amount of the terminal modifying agent used is preferably 0.1 mol equivalent or more, more preferably 0.3 mol equivalent or more, relative to the metal atom of the polymerization initiator involved in the polymerization reaction. By using an amount of the terminal modifying agent of 0.1 mol equivalent or more in the above reaction, the modification reaction can be sufficiently progressed and the dispersibility of the filler can be suitably improved. In addition, the amount of the terminal modifying agent used is preferably 1.5 mol equivalent or less, more preferably 1.2 mol equivalent or less, relative to the metal atom of the polymerization initiator involved in the polymerization reaction.

The temperature of the above reaction is usually the same as that of the polymerization reaction, and is preferably -20°C to 150°C, and more preferably 0 to 120°C. If the reaction temperature is too low, the viscosity of the modified conjugated diene polymer (P) tends to increase. On the other hand, if the reaction temperature is too high, the polymerization active terminals are easily deactivated. The reaction time is preferably 1 minute to 5 hours, and more preferably 2 minutes to 1 hour.

When a compound having a protecting group (such as a trimethylsilyl group) is used as a terminal modifier in producing the modified conjugated diene polymer (P), a modified conjugated diene polymer having a protecting group derived from the terminal modifier can be obtained. The modified conjugated diene polymer having a protecting group derived from the terminal modifier may be used in the subsequent steps as the modified conjugated diene polymer (P) after a part or all of the protecting groups are replaced with hydrogen. Furthermore, when a protecting group-containing compound is used as the terminal modifier, the modified conjugated diene polymer modified by the terminal modifier may be further reacted with an onium salt generating agent. In this case, a polymer having an onium salt structure at the polymer end can be obtained as the modified conjugated diene polymer (P). The modified conjugated diene polymer (P) having an onium salt structure can improve the shape retention of the crosslinked body obtained using the polymer composition. The onium salt generating agent is a Bronsted acid or a compound that generates a Bronsted acid when in contact with water.

As a specific method for obtaining the modified conjugated diene polymer (P), it is preferable to carry out polymerization of the monomer in a solvent in the presence of a polymerization initiator in the above-mentioned polymerization step by a continuous polymerization method, and then in the subsequent modification step, to obtain a polymer solution by reacting the polymer having an active end with the compound (M). The polymer contained in the polymer solution can be isolated by a known desolvation method and a drying operation such as heat treatment.

When removing the solvent from the polymer solution obtained by reacting the polymer having an active end with the compound (M), it is preferable to carry out the following solvent removal step.
Desolvation step: A step of removing the solvent from the polymer solution obtained by the modification step without adding an extender oil to the polymer solution.

<Solvent removal step>
In the desolvation step, the solvent is removed from the polymer solution obtained by reacting a polymer having an active terminal with a compound (M) (i.e., the polymer solution obtained by the modification step) without adding an extender oil. In this way, the modified conjugated diene-based polymer (P) is isolated. The method for removing the solvent from the polymer solution is not particularly limited, and can be performed by known desolvation methods such as, for example, a method in which the polymer solution is contacted with water to remove the solvent (steam stripping) to separate the solvent, and the obtained polymer is dehydrated and dried; a method of devolatizing with a twin-screw extruder, etc.; a method of directly devolatizing with a drum dryer, etc. Among these, the method including steam stripping and dehydration/drying is preferable in that the desolvation treatment can be easily performed.

The manufacturing method including the above-mentioned polymerization step, modification step, and desolvation step can obtain a solid modified conjugated diene polymer (P) from which the solvent has been removed. One embodiment of the obtained modified conjugated diene polymer (P) is solid particles (crumbs), and another embodiment is a rubber veil obtained by compression molding the crumbs into a predetermined shape (e.g., a rectangular parallelepiped shape). The modified conjugated diene polymer (P) after desolvation does not contain extender oil. Furthermore, according to the present disclosure, a rubber bale containing the modified conjugated diene polymer (P) and not containing extender oil can be obtained.

Note that "the modified conjugated diene polymer (P) after desolvation does not contain extender oil" means that the amount of extender oil in the modified conjugated diene polymer (P) is, for example, 0.5 parts by mass or less, preferably 0.1 parts by mass or less, and more preferably 0.01 parts by mass or less, per 100 parts by mass of the modified conjugated diene polymer (P). "Rubber bale containing no extender oil" means that the amount of extender oil in the rubber bale is, for example, 0.5 parts by mass or less, preferably 0.1 parts by mass or less, and more preferably 0.01 parts by mass or less, per 100 parts by mass of the rubber bale. By using such a modified conjugated diene polymer (P) (preferably a rubber bale of the modified conjugated diene polymer (P)), a crosslinked body having high strength and excellent abrasion resistance and rolling resistance can be obtained. In addition, a rubber bale having excellent contamination resistance can be obtained.

After the solvent removal and drying treatment, the water content of the modified conjugated diene polymer (P) is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and even more preferably 0.5% by mass or less. The Mooney viscosity of the above-mentioned modified conjugated diene polymer (P) measured at 160°C is a value measured using the modified conjugated diene polymer (P) after the solvent removal and drying treatment.

<Polymer composition>
The polymer composition of the present disclosure contains the above-mentioned modified conjugated diene-based polymer (P) and at least one filler (hereinafter also simply referred to as "filler") selected from the group consisting of silica, carbon black, and a compound represented by the following formula (1):
nM ¹・mSiO _k・iH ₂ O…(1)
(In formula (1), ^M1 is at least one selected from the group consisting of any one of metals aluminum, magnesium, titanium, zirconium, and calcium (hereinafter also referred to as "specific metal"), oxides of specific metals, hydroxides of specific metals, and carbonates of specific metals. n is an integer of 1 to 5, m is an integer of 0 to 10, k is an integer of 2 to 5, and i is an integer of 0 to 10.)

<Filler>
[B] Silica The polymer composition of the present disclosure may contain silica as a filler. The amount of silica is preferably in the range of 20 to 160 parts by mass, more preferably in the range of 30 to 150 parts by mass, per 100 parts by mass of the rubber component containing the modified conjugated diene polymer (P). When the amount of silica is 20 parts by mass or more per 100 parts by mass of the rubber component, the rolling resistance, fracture properties and abrasion resistance of the crosslinked body obtained from the polymer composition can be sufficiently improved. In addition, when the amount of silica is 160 parts by mass or less, the processability of the polymer composition can be sufficiently improved.

In this specification, the "rubber component" contained in the polymer composition refers to a polymer that can be cured to obtain a cured product that exhibits rubber elasticity. The cured product exhibits the property of undergoing large deformation with a small force at room temperature (for example, deformation that stretches to more than twice its original size when stretched at room temperature) and rapidly returning to almost its original shape when the force is removed.

The silica is not particularly limited, and examples thereof include wet silica (hydrated silicic acid), dry silica (anhydrous silicic acid), calcium silicate, aluminum silicate, rice husk silica, and the like. Among these, wet silica is preferred. Silica may be used alone or in combination of two or more types. The BET specific surface area of silica (a value measured in accordance with ISO 5794/1) is preferably in the range of 40 to 350 m ² /g, more preferably in the range of 80 to 300 ^{m 2} /g, and particularly preferably in the range of 120 to 250 m ² /g. Silica having a BET specific surface area in this range has the advantage of being able to achieve both dispersibility in modified conjugated diene polymers and rubber reinforcement properties. Examples of such silica that can be used include commercially available products such as "Nipsil AQ" (BET specific surface area = 205 ^m2 /g) and "Nipsil KQ" manufactured by Tosoh Silica Corporation, and "Ultrasil VN3" (BET specific surface area = 175 ^m2 /g) manufactured by Degussa.

The polymer composition may contain two or more kinds of silica having different specific surface areas. Specifically, a first silica having a CTAB (cetyltrimethylammonium bromide) specific surface area of 180 m ² /g or more, a BET specific surface area of 185 m ² /g or more, and an aggregate size of 45 nm or more may be used in combination with a second silica having a CTAB specific surface area of 95 m ² /g or less and a BET specific surface area of 100 m ² /g or less. The CTAB specific surface area of the silica is measured in accordance with ASTM D3765-92. By using such a first silica and a second silica in combination, it becomes possible to disperse the first silica, which has a small average primary particle size but a relatively large aggregate size, well in the rubber component. This improves the dispersibility of the silica, and excellent rubber breaking strength, abrasion resistance, fuel economy, and processability can be obtained.

The CTAB specific surface area of the first silica is preferably 190 m ² /g or more, more preferably 195 m ² /g or more, and even more preferably 197 ^{m 2} /g or more. When the CTAB specific surface area is 180 m ² /g or more, the rubber breaking strength and abrasion resistance tend to be sufficiently improved. The CTAB specific surface area is preferably 350 m ² /g or less, more preferably 300 m ² /g or less, and even more preferably 250 m ² /g or less. When the CTAB specific surface area is 350 m ² /g or less, the dispersibility is good and the agglomeration is difficult, so the deterioration of physical properties tends to be suppressed.

The BET specific surface area of the first silica is preferably 190 m ² /g or more, more preferably 195 m ² /g or more, and even more preferably 210 m ² /g or more. When the BET specific surface area is 185 m ² /g or more, the rubber breaking strength and abrasion resistance tend to be sufficiently improved. The BET specific surface area is preferably 350 m ² /g or less, more preferably 300 m ² /g or less, and even more preferably 260 m ² /g or less. When the BET specific surface area is 350 m ² /g or less, the dispersibility is good and the agglomeration is difficult, so that the deterioration of physical properties tends to be suppressed. The BET specific surface area of the silica is measured in accordance with ASTM D3037-81.

The aggregate size of the first silica is 45 nm or more, preferably 50 nm or more, more preferably 55 nm or more, and even more preferably 60 nm or more. The aggregate size is preferably 100 nm or less, more preferably 80 nm or less, even more preferably 70 nm or less, and particularly preferably 67 nm or less. By having such an aggregate size, it is possible to provide excellent fuel efficiency and wear resistance while having good dispersibility (processability). The aggregate size of silica can be measured by the method described in JP 2011-140613 A.

The average primary particle diameter of the first silica is preferably 25 nm or less, more preferably 22 nm or less, even more preferably 17 nm or less, and particularly preferably 14 nm or less. The lower limit of the average primary particle diameter is not particularly limited, but is preferably 3 nm or more, more preferably 5 nm or more, and even more preferably 7 nm or more. Although it has such a small average primary particle diameter, the dispersibility (processability) of the silica can be further improved by a carbon black-like structure having the above aggregate size, and the fuel efficiency and wear resistance can be further improved. The average primary particle diameter of the silica can be determined by observing the silica with a transmission or scanning electron microscope, measuring the particle diameters of 400 or more primary particles of silica observed within the field of view, and averaging the measured particle diameters.

The CTAB specific surface area of the second silica is preferably 10 m ² /g or more, more preferably 20 m ² /g or more, and even more preferably 30 m ² /g or more. When the CTAB specific surface area is 10 m ² /g or more, the effect of improving the reinforcing property is high, and it tends to be easy to ensure the mechanical strength and abrasion resistance required for the polymer composition for obtaining rubber for tires. The CTAB specific surface area is preferably 80 m ² /g or less, more preferably 60 m ² /g or less, and even more preferably 50 m ² /g or less. When the CTAB specific surface area is 95 m ² /g or less, the dispersibility of the silica can be ensured, and it tends to be easy to improve the rubber breaking strength and abrasion resistance.

The BET specific surface area of the second silica is preferably 10 m ² /g or more, more preferably 20 m ² /g or more, and even more preferably 30 m ² /g or more. When the BET specific surface area is 10 m ² /g or more, the effect of improving the reinforcing property is high, and it tends to be easy to ensure the mechanical strength and abrasion resistance required for the polymer composition for obtaining rubber for tires. The BET specific surface area is preferably 85 m ² /g or less, more preferably 60 m ² /g or less, and even more preferably 50 m ² /g or less. When the BET specific surface area is 100 m ² /g or less, it is possible to ensure the dispersibility of the silica, and it tends to be easy to improve the rubber breaking strength and abrasion resistance.

The average primary particle diameter of the second silica is preferably 20 nm or more, more preferably 25 nm or more, even more preferably 30 nm or more, particularly preferably 35 nm or more, and most preferably 55 nm or more. The average primary particle diameter is preferably 500 nm or less, more preferably 200 nm or less, even more preferably 100 nm or less, and particularly preferably 70 nm or less. By having such an average primary particle diameter, it is possible to enhance the effect of improving the rubber fracture strength and abrasion resistance.

[C] Carbon Black The polymer composition of the present disclosure preferably contains carbon black as a filler from the viewpoint of the fracture properties and abrasion resistance of the crosslinked body obtained from the polymer composition. The carbon black is not particularly limited, and examples thereof include GPF, FEF, HAF, ISAF, and SAF grade carbon black. The nitrogen adsorption specific surface area (N ₂ SA) of the carbon black is not particularly limited, but is preferably 50 to 200 m ² /g, and more preferably 70 to 150 ^{m 2} /g, because it is more excellent in terms of the effects of the present disclosure. N ₂ SA is the value obtained by measuring the amount of nitrogen adsorption on the carbon black surface according to JIS K6217-2:2001 "Part 2: Determination of specific surface area - Nitrogen adsorption method - Single point method". These carbon blacks may be used alone or in combination of two or more types. The amount of carbon black added is preferably within a range from 1 to 150 parts by mass, and more preferably from 3 to 120 parts by mass, per 100 parts by mass of the rubber component containing the modified conjugated diene polymer (P).

[D] Compound represented by formula (1) Specific examples of the compound represented by formula (1) (hereinafter also referred to as "inorganic compound (D)") include alumina (Al ₂ O ₃ ) such as γ-alumina and α-alumina, alumina monohydrate (Al ₂ O ₃ ·H ₂ O) such as boehmite and diaspore, aluminum hydroxide [Al(OH) ₃ ] such as gibbsite and bayerite, aluminum carbonate [Al ₂ (CO ₃ ) ₃ ], magnesium hydroxide [Mg(OH) ₂ ], magnesium oxide (MgO), magnesium carbonate (MgCO ₃ ), talc (3MgO ·4SiO ₂ ·H ₂ O), attapulgite (5MgO ·8SiO ₂ ·9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO), calcium hydroxide [Ca(OH) ₂ ], magnesium aluminum oxide (MgO.Al ₂ O ₃ ), clay (Al ₂ O _{3.2SiO 2} ), kaolin (Al ₂ O _{3.2SiO 2.2H 2} O), pyrophyllite (Al 2 O _3.4SiO 2.H 2 O), bentonite (Al ₂ O 3.4SiO _{2.2H 2} O), aluminum silicate ( _{Al 2 SiO 5 ,} Al _{4.3SiO 4.5H 2} O, etc.), magnesium silicate (Mg ₂ SiO ₄ , MgSiO ₃ , etc.), calcium silicate (Ca ₂ SiO ₄ , etc.), calcium aluminum silicate ( _{Al 2 O 3.CaO.2SiO 2} , etc.), calcium magnesium silicate (CaMgSiO ₄ ), calcium carbonate (CaCO ₃ ) _, zirconium oxide (ZrO ₂ ), zirconium hydroxide [ZrO(OH) _2.nH2O ], zirconium carbonate [Zr( _CO3 ) ₂ ], and _the like.

In the polymer composition of the present disclosure, the amount of filler is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 60 parts by mass or more, per 100 parts by mass of the rubber component. The amount of filler is preferably 200 parts by mass or less, more preferably 160 parts by mass or less, and even more preferably 120 parts by mass or less. When the amount of filler in the polymer composition is within the above range, by applying the polymer composition to a tire tread, it is possible to achieve a high degree of compatibility between the rolling resistance of the tire, the braking performance on wet road surfaces, the handling performance on dry road surfaces, and the abrasion resistance.

The polymer composition of the present disclosure may further contain various components shown below in addition to the modified conjugated diene polymer (P) and the filler.

[E] Other Rubber Components The polymer composition of the present disclosure preferably further contains at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber, emulsion-polymerized styrene-butadiene rubber, solution-polymerized styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene-propylene rubber, and ethylene-butadiene rubber, as a rubber component other than the modified conjugated diene polymer (P). Among these, it is preferable to contain at least one of natural rubber, butadiene rubber, and styrene-butadiene rubber. When the other rubber components are mixed with the modified conjugated diene polymer (P), they are mixed during kneading using a Banbury mixer, roll, or the like, which is usually performed.

The ratio of the modified conjugated diene polymer (P) to the other rubber components is preferably 5 to 95 parts by mass of the modified conjugated diene polymer (P) and 5 to 95 parts by mass of the other rubber components per 100 parts by mass of the combined total of the modified conjugated diene polymer (P) and the other rubber components, and more preferably 20 to 90 parts by mass of the modified conjugated diene polymer (P) and 10 to 80 parts by mass of the other rubber components. In particular, when the modified conjugated diene polymer (P) is 35 to 85 parts by mass and the other rubber components are 15 to 65 parts by mass, it is suitable as a polymer composition for producing rubber for tires.

When producing the polymer composition of the present disclosure, liquid rubber can be used for some or all of the other rubber components in order to further improve dry grip performance, wet grip performance, and blowout resistance.

Liquid rubbers include liquid polyisoprene (liquid IR), liquid polybutadiene (liquid BR), liquid styrene-butadiene copolymer (liquid SBR), and liquid ethylene-propylene copolymer (liquid EP). For example, liquid SBR with a weight average molecular weight of 1,000 to 100,000, preferably 2,000 to 80,000, can be used. The weight average molecular weight refers to the weight average molecular weight converted into polystyrene as analyzed by gel permeation chromatography (GPC). Liquid rubber refers to one that has fluidity at 23°C.

[F] Resin The polymer composition of the present disclosure may contain a resin (hereinafter, also simply referred to as "[F] resin"). The [F] resin may be thermoplastic or thermosetting. From the viewpoint of obtaining a crosslinked body having excellent properties such as strength, abrasion resistance, and crack growth resistance, the [F] resin is preferably at least one selected from the group consisting of styrene-based resins, polyethylene, C5-based resins, hydrogenated C5-based resins, C9-based resins, hydrogenated C9 resins, C5/C9-based resins, hydrogenated C5/C9-based resins, dicyclopentadiene-based resins, dicyclopentadiene/C9-based resins, hydrogenated dicyclopentadiene-based resins, hydrogenated dicyclopentadiene/C9-based resins, alkylphenol-based resins, coumarone-indene resins, terpene-based resins, and hydrogenated terpene-based resins. The resin [F] is preferably a thermoplastic resin, and more preferably at least one selected from the group consisting of styrene resins, polyethylene, C5 resins, hydrogenated C5 resins, C9 resins, hydrogenated C9 resins, C5/C9 resins, hydrogenated C5/C9 resins, coumarone-indene resins, terpene resins, and hydrogenated terpene resins. The resin [F] may be used alone or in combination of two or more.

When the [F] resin is blended into the polymer composition, the blending ratio of the [F] resin is preferably 1 part by mass or more per 100 parts by mass of the rubber component contained in the polymer composition. By blending 1 part by mass or more of the [F] resin, the effect of improving the abrasion resistance, breaking strength, and crack growth resistance by adding the [F] resin can be sufficiently enhanced in the crosslinked body obtained using the polymer composition, which is preferable. When the [F] resin is blended into the polymer composition, the blending ratio of the [F] resin is more preferably 5 parts by mass or more per 100 parts by mass of the rubber component, and even more preferably 10 parts by mass or more. In addition, from the viewpoint of maintaining various performances of the rubber composition well, the blending ratio of the [F] resin is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 50 parts by mass or less per 100 parts by mass of the rubber component contained in the polymer composition. Note that one type of [F] resin may be used alone, or two or more types may be used in combination.

[G] Silane coupling agent In the present disclosure, the dispersibility of silica can be further improved by blending a silane coupling agent. The silane coupling agent used is not particularly limited, but a sulfur-containing silane coupling agent is preferable. Examples of sulfur-containing silane coupling agents include bis(3-triethoxysilylpropyl)tetrasulfide, bis(3-triethoxysilylpropyl)disulfide, 3-trimethoxysilylpropylbenzothiazoletetrasulfide, γ-mercaptopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-[ethoxybis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silyl]propane-1-thiol (for example, manufactured by Evonik, trade name "Si363"), and mercapto-based silane compounds such as NXT and NXT-Z manufactured by Momentive.

The amount of the silane coupling agent is preferably 1 to 20 parts by mass per 100 parts by mass of silica. If the amount of the silane coupling agent is less than 1 part by mass, the amount is too small and the effect of improving the dispersibility of the silica may not be fully obtained. On the other hand, if the amount of the silane coupling agent is more than 20 parts by mass, the processability and breaking elongation may decrease. It is more preferable that the amount of the silane coupling agent is 5 to 15 parts by mass per 100 parts by mass of silica. As the silane coupling agent, one type may be used alone, or two or more types may be used in combination.

[H] Crosslinking Agent The polymer composition of the present disclosure may contain a crosslinking agent. When the polymer composition of the present disclosure contains a crosslinking agent, a crosslinked body having improved strength and abrasion resistance can be obtained. Examples of the crosslinking agent include sulfur, halogenated sulfur, organic peroxides, quinone dioximes, organic polyamine compounds, and alkylphenol resins having methylol groups, and sulfur is usually used. The amount of the crosslinking agent is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the total amount of the rubber components contained in the polymer composition.

The polymer composition may contain a process oil commonly used for oil-extending elastomers as the oil for oil extension. The process oil is added to the polymer composition, for example, by directly adding the oil during rubber compounding. Preferred process oils include various oils known in the art, such as aromatic oils, paraffinic oils, naphthenic oils, vegetable oils such as soybean oil, sunflower oil, and oils with a low content of polycyclic aromatic compounds (low PCA oils), such as mild extraction solvates (MES), treated distillate aromatic extracts (TDAE), special residual aromatic extracts (SRAE), and heavy naphthenic oils. Examples of commercially available MES, TDAE, and SRAE include Catenex SNR (heavy paraffin obtained by dewaxing distillate oil with a solvent) manufactured by Shell as an MES, Vivatec 500 manufactured by H&R Wasag AG as a TDAE, and NC 140 manufactured by Japan Energy Corp. as an SRAE. The amount of process oil blended is preferably 10 to 100 parts by mass per 100 parts by mass of the total amount of polymer components contained in the polymer composition.

In addition to the components described above, the polymer composition may contain various additives that are generally used in polymer compositions for producing rubber for tires, such as antioxidants, zinc oxide, stearic acid, softeners, vulcanization accelerators, compatibilizers, vulcanization aids, processing aids, and scorch inhibitors. The blending ratios of these additives may be appropriately selected according to the various components, as long as they do not impair the effects of the present disclosure.

The polymer composition of the present disclosure can be applied to various rubber products as a crosslinked body by kneading the polymer components, fillers, and other components that are blended as necessary using a kneader such as an open kneader (e.g., roll) or an internal kneader (e.g., Banbury mixer), molding, and then crosslinking (vulcanizing). Specifically, the crosslinked body of the present disclosure can be applied to tire applications such as tire treads, undertreads, carcasses, sidewalls, and beads; sealing materials such as packings, gaskets, weather strips, and O-rings; interior and exterior skin materials for various vehicles such as automobiles, ships, aircraft, and railways; building materials; anti-vibration rubbers for industrial machinery and equipment; various hoses and hose covers such as diaphragms, rolls, radiator hoses, and air hoses; belts such as power transmission belts; linings; dust boots; medical equipment materials; fenders; insulating materials for electric wires; and other industrial products.

The modified conjugated diene polymer (P) can provide a crosslinked product having excellent physical properties required for tire applications, such as rolling resistance (fuel economy), strength, and abrasion resistance. Therefore, a polymer composition containing the modified conjugated diene polymer (P) can be suitably used as a material for tire treads, sidewalls, or both.

Tires can be manufactured in the usual way. For example, the polymer composition is mixed in a kneader, formed into a sheet, and then placed in a predetermined position (for example, on the outside of the carcass in the case of a sidewall) in the usual way and vulcanized to form the tread rubber or sidewall rubber, to obtain a pneumatic tire.

According to the present disclosure described above in detail, the following means are provided.
[Means 1] A modified conjugated diene polymer having a Mooney viscosity of 80 or more and 150 or less measured at 160°C and having a partial structure derived from a compound (M) having a nitrogen atom and a hydrocarbyloxysilyl group in one molecule.
[Means 2] The modified conjugated diene polymer according to [Means 1], having a 1,2-vinyl group content of 60 mass% or less.
[Means 3] The modified conjugated diene-based polymer according to [Means 1] or [Means 2], which has structural units derived from an aromatic vinyl compound, and the content of the structural units derived from the aromatic vinyl compound is 45 mass% or less based on the total amount of structural units possessed by the modified conjugated diene-based polymer.
[Means 4] The modified conjugated diene polymer according to any one of [Means 1] to [Means 3], having a weight average molecular weight measured by gel permeation chromatography of 7.0 x 10 ⁵ or more and 3.0 x 10 ⁶ or less.
[Means 5] The modified conjugated diene polymer according to any one of [Means 1] to [Means 4], in which the molecular weight distribution (Mw/Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography is 1.60 or more and 4.00 or less.
[Means 6] The modified conjugated diene polymer according to any one of [Means 1] to [Means 5], wherein the compound (M) contains a compound having two or more hydrocarbyloxysilyl groups.
[Means 7] A method for producing a modified conjugated diene polymer according to any one of [Means 1] to [Means 6], comprising: a polymerization step of polymerizing a monomer containing a conjugated diene compound in the presence of a polymerization initiator to obtain a conjugated diene polymer having an active end; and a modification step of reacting the conjugated diene polymer having an active end with the compound (M).
[Means 8] The method for producing a modified conjugated diene-based polymer according to [Means 7], wherein in the polymerization step, the monomer is polymerized in a solvent in the presence of the polymerization initiator by a continuous polymerization system, and in the modification step, the polymer having the active end is reacted with the compound (M) to obtain a polymer solution, and the method further comprises a desolvation step of removing the solvent from the polymer solution without adding an extender oil to the polymer solution.
[Means 9] A rubber veil containing the modified conjugated diene polymer according to any one of [Means 1] to [Means 6] and not containing an extender oil.
[Means 10] A polymer composition comprising the modified conjugated diene polymer according to any one of [Means 1] to [Means 6] and at least one filler selected from the group consisting of silica, carbon black and the compound represented by the above formula (1).
[Means 11] The polymer composition according to [Means 10], further comprising at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber, emulsion-polymerized styrene-butadiene rubber, solution-polymerized styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene-propylene rubber, and ethylene-butadiene rubber, which is different from the modified conjugated diene polymer.
[Means 12] The polymer composition according to [Means 10] or [Means 11], further comprising a resin.
[Means 13] A crosslinked product obtained by crosslinking the polymer composition according to any one of [Means 10] to [Means 12].
[Means 14] A tire in which one or both of a tread and a sidewall are made using the polymer composition according to any one of [Means 10] to [Means 12].

The present invention will be explained in detail below based on examples, but the present invention is not limited to the following examples. Note that "parts" and "%" in the following synthesis examples, examples, and comparative examples are based on mass unless otherwise specified. The methods for measuring various physical properties of the polymer are shown below.

Bound styrene content (%): Calculated by 400 MHz ¹ H-NMR measurement using deuterated chloroform as a solvent.
Vinyl group content (%): Calculated by 400 MHz ¹ H-NMR measurement.
Weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of the polymer: A chart (GPC curve) based on the molecular weight in terms of polystyrene was obtained by gel permeation chromatography (GPC), and the weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of the polymer were determined based on the obtained chart. The specific measurement conditions for GPC are as follows:
(GPC measurement conditions)
Measuring instrument: HLC-8020 (manufactured by Tosoh Corporation)
Column: GMH-HR-H (manufactured by Tosoh Corporation), two columns connected in series Detector: Differential refractometer RI-8020 (manufactured by Tosoh Corporation)
Eluent: tetrahydrofuran Column temperature: 40°C
Flow rate: 1.0 mL/min Sample concentration: 10 mg/20 mL
Mooney viscosity (ML1+4, 160° C.): Measured under the conditions specified in JIS K6300-1, except that the measurement temperature was 160° C. In detail, the measurement was performed using an L rotor, with preheating for 1 minute, rotor operation time for 4 minutes, and a temperature of 160° C.
Water content: 10 g of modified conjugated diene polymer was placed in a halogen heater heated to 110° C. and heated until the mass change rate of the sample became less than 1 mg/90 seconds. The water content in the sample (hereinafter also referred to as “VM”) was calculated from the mass change after heating. The formula for calculating VM is as follows:
VM (mass%)=(sample mass before heating−sample mass after heating)/sample mass before heating×100
Glass transition temperature: In accordance with JIS K6240:2011, the glass transition temperature was determined from the inflection point of the DSC curve in the range of −100° C. to 40° C. The specific measurement conditions for the glass transition temperature are as follows.
(DSC measurement conditions)
Measurement device: Q1000 Differential Scanning Calorimeter (DSC) (manufactured by TA Instruments)
Heating rate: 10° C./min
- Stain resistance of the veil: A migration staining test (accelerated heating method) was carried out in accordance with JIS K6267: 2006. The presence or absence of staining on the stained material was confirmed by visual inspection.

[Example 1: Synthesis of modified conjugated diene polymer A-1]
Into a 50-liter autoclave reactor (first reactor), 85.4 g/min of 1,3-butadiene and 24.4 g/min of styrene as monomers, 830.6 g/min of cyclohexane as a solvent, 0.6 g/min of tetrahydrofuran as a vinyl content regulator (randomizer), and 62.3 mg/min of n-butyllithium as a polymerization initiator were continuously charged, and the temperature inside the reactor was controlled at 77° C.
After the additional 1,3-butadiene was added at a rate of 12.2 g/min, the polymer solution was continuously discharged from the first reactor at a rate of 953.3 g/min, and 1,1'-(1,4-phenylene)bis(N-(3-(triethoxysilyl)propyl)methanimine (hereinafter referred to as "compound N-Si-1") was added to the discharged polymer solution at a rate of 116.0 mg/min, and the solution was continuously introduced into the second reactor to carry out the reaction. Then, di-tert-butyl-p-cresol was added in an amount of 0.88 parts by mass relative to 100 parts by mass of the polymer to obtain a polymer solution. The obtained polymer solution was then used as it was to remove the solvent by steam stripping, and dried by a heated roll adjusted to 110°C to obtain a modified conjugated diene polymer A-1. A part of the modified conjugated diene polymer after drying was used to produce a bale by the molding method described below.

<How to mold rubber bales>
20 kg of the modified conjugated diene polymer A-1 obtained above was compressed for 12 seconds at a molding pressure of 10 MPa and a molding temperature of 60° C. to obtain a rectangular bale of modified conjugated diene polymer A-1.

Table 1 shows various physical properties of modified conjugated diene polymer A-1. In Table 1, "-" indicates that the reagent was not added to the polymerization system. Regarding the evaluation results of the contamination resistance of the veil, Table 1 shows "A" if the contaminated material after the test has not discolored compared to before the test or has only slightly discolored, and "B" if the contaminated material after the test has discolored moderately or significantly compared to before the test (same for Table 2). If the contaminated material after the test has not discolored compared to before the test or has only slightly discolored, the veil can be evaluated as having excellent contamination resistance.

[Examples 2 to 17: Synthesis of modified conjugated diene polymers A-2 to A-17]
Polymerization, desolvation and drying were carried out in the same manner as in Example 1, except that the types and amounts of reagents used were as shown in Tables 1 and 2, to obtain modified conjugated diene polymers A-2 to A-17. In addition, bales were produced using each of the modified conjugated diene polymers A-2 to A-17. Various physical property values of the obtained modified conjugated diene polymers A-2 to A-17 are shown in Tables 1 and 2.

[Comparative Example 1: Synthesis of Modified Conjugated Diene Polymer A-18]
The types and amounts of reagents used were as shown in Table 2, and polymerization, desolvation and drying were carried out in the same manner as in Example 1, except that extender oil (process oil T-DAE manufactured by ENEOS Corporation) was added at a rate of 18.3 g/min to the polymer solution containing the produced modified conjugated diene polymer, to obtain a modified conjugated diene polymer A-18. In addition, a veil was produced using the modified conjugated diene polymer A-18.

[Comparative Examples 2 and 3: Synthesis of Modified Conjugated Diene Polymers A-19 and A-20]
Modified conjugated diene polymers A-19 and A-20 were obtained by polymerization, desolvation and drying in the same manner as in Example 1, except that the types and amounts of reagents used were as shown in Table 2. Bales were also produced using each of the modified conjugated diene polymers A-19 and A-20.

[Comparative Example 4: Synthesis of conjugated diene polymer A-21]
Into a 50-liter reactor (first reactor), 1,3-butadiene as monomers were continuously charged at a rate of 42.1 g/min, styrene at a rate of 29.9 g/min, cyclohexane as a solvent at a rate of 415.9 g/min, tetrahydrofuran as a vinyl content regulator (randomizer) at a rate of 26.9 g/min, and n-butyllithium as a polymerization initiator at a rate of 26.5 mg/min, and the temperature inside the reactor was controlled at 70°C.
The polymer solution was continuously discharged from the first reactor at a rate of 518.6 g/min, silicon tetrachloride (SiCl ₄ ) was added to the discharged polymer solution at a rate of 11.7 mg/min, and the solution was continuously introduced into the second reactor to carry out the reaction. At the outlet of the second reactor, di-tert-butyl-p-cresol was added in an amount of 0.88 parts by mass relative to 100 parts by mass of the polymer to obtain a polymer solution. To the polymer solution containing the produced conjugated diene polymer, extender oil (ENEOS Corporation process oil T-DAE) was added at a rate of 28.4 g/min, and then the obtained polymer solution was desolvated by steam stripping and dried with a heat roll adjusted to 110 ° C. to obtain a conjugated diene polymer A-21. In addition, a veil was produced using the modified conjugated diene polymer A-21.

[Comparative Example 5: Synthesis of modified conjugated diene polymer A-22]
Into a nitrogen-substituted 5-liter autoclave reactor, 2,000 g of cyclohexane, 31.6 g of tetrahydrofuran, 122 g of styrene, and 320 g of 1,3-butadiene were charged. After adjusting the temperature of the contents of the reactor to 10°C, 4.75 mmol of n-butyllithium was added as a polymerization initiator to initiate polymerization. The polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85°C. After the polymerization conversion rate reached 99%, 10 g of 1,3-butadiene was added over 2 minutes, and then 2.12 mmol of compound N-Si-1 was added and reacted for 15 minutes. 3.96 g of 2,6-di-tert-butyl-p-cresol was added to the resulting polymer solution containing the modified conjugated diene polymer. Next, the solvent was removed by steam stripping, and the mixture was dried with a hot roll adjusted to 110°C to obtain a modified conjugated diene polymer A-22. Also, a veil was produced using the modified conjugated diene polymer A-22.

Details of the abbreviations in Tables 1 and 2 are as follows.
(Initial end modification agent)
INI-1 to INI-4: Compounds represented by the following formulas (INI-1) to (INI-4), respectively INI-5: Piperidine INI-6: N-trimethylsilylpiperazine

(Branching Agent)
Si-1: Trimethoxy(4-vinylphenyl)silane (terminal modifier)
N-Si-1 to N-Si-5: Compounds represented by the following formulas (N-Si-1) to (N-Si-5), respectively.

[Examples 18 to 41, Comparative Examples 6 to 14]
Polymer compositions P-1 to P-33 were produced by blending the components according to the blending recipes shown in Tables 3 to 5 and melt-kneading the blends. Kneading was carried out in the following manner.
A batch mixer equipped with a temperature control device (manufactured by Toyo Seiki Seisakusho; product name: Labo Plastomill) was used to knead the rubber components ((modified) conjugated diene polymer, polybutadiene rubber, natural rubber), extender oil, silica, silane coupling agent, carbon black, thermoplastic resin, stearic acid, antioxidant, and zinc oxide in the first stage of kneading, with the temperature set at 100°C, the number of revolutions at 60 rpm, and the kneading time at 5 minutes. The temperature of the kneaded products discharged from the mixer was about 150°C in all cases.
Next, in the second stage of kneading, the kneaded product obtained in the first stage of kneading was cooled to room temperature, and then a vulcanization accelerator and sulfur were added to the mixer, and the temperature was adjusted to 70°C, and the kneading was performed under the conditions of a rotation speed of 60 rpm and a kneading time of 1.5 minutes to obtain each polymer composition. The temperature of the kneaded product discharged from the mixer was 100°C or lower when it was discharged. Next, each of the obtained polymer compositions was vulcanized and molded in a vulcanization press at 160°C for a predetermined time to obtain a vulcanized rubber as a crosslinked body. The following physical property evaluations were performed using the obtained vulcanized rubber. The results are shown in Table 2. In Comparative Example 8, the processability of the polymer composition was poor, and a polymer composition and vulcanized rubber that could be evaluated were not obtained.

・Loss tangent (3% tan δ @ 50℃ rolling resistance)
Using vulcanized rubber as a measurement sample, a shear type dynamic spectrometer (manufactured by TA Instruments) was used to measure the ratio of loss modulus G'' to storage modulus G' (50°C tan δ) under conditions of an angular velocity of 100 radians per second, a temperature of 50°C, and a shear strain of 3%. Examples 18 to 37 and Comparative Examples 7 to 10 are shown as indexes with Comparative Example 6 set to 100. Example 38 is shown as an index with Comparative Example 11 set to 100, Example 39 is shown as an index with Comparative Example 12 set to 100, Example 40 is shown as an index with Comparative Example 13 set to 100, and Example 41 is shown as an index with Comparative Example 14 set to 100. A larger value indicates a smaller rolling resistance and better fuel economy performance.
Tensile strength ((TB*EB)/2)
A tensile test was conducted in accordance with JIS K6251:2010 using vulcanized rubber as a measurement sample. Here, a dumbbell-shaped No. 3 was used as a test sample, and the stress at break (TB, MPa) and elongation at break (EB, %) were measured at room temperature. The larger the TB and EB values, the higher the breaking strength and the higher the mechanical strength of the material. The strength was calculated according to the formula (TB*EB)/2. The measurement results are shown as indexes for Examples 18 to 37 and Comparative Examples 7 to 10, with Comparative Example 6 set to 100. In addition, Comparative Example 11 for Example 38, Comparative Example 12 for Example 39, Comparative Example 13 for Example 40, and Comparative Example 14 for Example 41, are each shown as an index set to 100. The larger the value, the higher and better the tensile strength.
- Abrasion resistance (Lambourn abrasion test)
Using vulcanized rubber as a measurement sample, measurements were performed in accordance with JIS K6264 using a Lambourn abrasion tester (manufactured by Ueshima Seisakusho Co., Ltd.) at a load of 44.1 N, a slip ratio of 25%, and 25°C. Examples 18 to 37 and Comparative Examples 7 to 10 are shown as indexes with Comparative Example 6 set to 100. Example 38 is shown as an index with Comparative Example 11 set to 100, Example 39 is shown as an index with Comparative Example 12 set to 100, Example 40 is shown as an index with Comparative Example 13 set to 100, and Example 41 is shown as an index with Comparative Example 14 set to 100. A larger value indicates better abrasion resistance.

Details of the abbreviations in Tables 3 to 5 are as follows:
*1: ENEOS Materials Corporation, product name "BR01"
*2: ENEOS Corporation, product name "NC-140"
*3: Silica 1: Rhodia, trade name "ZEOSIL 1165MP", Silica 2: Evonik, trade name "ULTRASIL 9100GR", Silica 3: Evonik, trade name "ULTRASIL VN3"
*4: Evonik, product name "Si75"
*5: Tokai Carbon Co., Ltd., Seast 3
*6: Resin 1: T-REZ PR802 (C5/C9 resin) manufactured by ENEOS Corporation, Resin 2: T-REZ PR803 (hydrogenated DCPD/C9 resin) manufactured by ENEOS Corporation
*7: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, product name "Ozonone 6C" manufactured by Seiko Chemical Co., Ltd.
*8: 1,3-diphenylguanidine, product name "Noxeler D" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
*9: N-cyclohexyl-2-benzothiazolyl sulfenamide, product name "Noccela CZ" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

As shown in Tables 3 to 5, it was found that the polymer compositions P-1 to P-20 and P-26, P-28, P-30, and P-32 of Examples 18 to 41, which contain the modified conjugated diene polymers of Examples 1 to 17, can produce crosslinked bodies with a good balance of improved rolling resistance, abrasion resistance, and strength. More specifically, according to the polymer compositions P-1 to P-10 of Examples 18 to 27, which contain modified conjugated diene polymers A-1 to A-3, A-6 to A-8, A-10, A-11, A-13, and A-14, in which only a terminal end modifier is used as the compound (M) during polymerization and which have a 160°C Mooney viscosity in the range of 80 to 150, a crosslinked body with improved rolling resistance, abrasion resistance, and strength in a well-balanced manner was obtained, compared to the polymer compositions P-21, P-22, P-24, and P-25 of Comparative Examples 6, 7, 9, and 10, which contain (modified) conjugated diene polymers A-18 to A-22, which have a 160°C Mooney viscosity outside the range of 80 to 150, instead of the modified conjugated diene polymers A-1 to A-3, A-6 to A-8, A-10, A-11, A-13, and A-14.

In addition, polymer compositions P-11 to P-14 of Examples 28 to 31, which use an initiating end modifier and a terminating end modifier as compound (M) and contain modified conjugated diene polymers A-4, A-5, A-9, and A-12 having a 160°C Mooney viscosity in the range of 80 to 150, also provided crosslinked bodies with a good balance of improved rolling resistance, abrasion resistance, and strength. Furthermore, a comparison of the results of Example 18 with those of Examples 28 and 29 showed that the rolling resistance and abrasion resistance could be improved by further using an initiating end modifier as compound (M).

Furthermore, in the polymer compositions P-15 to P-18 of Examples 32 to 35, which used modified conjugated diene polymers A-15 to A-17 in which the styrene content and 1,2-vinyl content of the modified conjugated diene polymer were changed, a significant improvement was observed especially in tensile strength and abrasion resistance. Furthermore, when no resin was added, a significant improvement was observed in rolling resistance while improving tensile strength and abrasion resistance (Examples 36 and 37).

Furthermore, by comparing Example 38 with Comparative Example 11, Example 39 with Comparative Example 12, Example 40 with Comparative Example 13, and Example 41 with Comparative Example 14, it was found that a crosslinked product with a well-balanced improvement in rolling resistance, abrasion resistance, and strength can be obtained even when only a terminal end modifier is used as compound (M), a modified conjugated diene polymer having a 160°C Mooney viscosity in the range of 80 to 150 is used, and natural rubber is used in combination as the rubber component. The veils formed from the modified conjugated diene polymers of Examples 1 to 17 also had excellent stain resistance.

Claims (14)

has a partial structure derived from a compound (M) having a nitrogen atom and a hydrocarbyloxysilyl group in one molecule,
A modified conjugated diene polymer having a Mooney viscosity measured at 160° C. of 80 or more and 150 or less. The modified conjugated diene polymer according to claim 1, having a 1,2-vinyl group content of 60% by mass or less. having a structural unit derived from an aromatic vinyl compound,
The modified conjugated diene polymer according to claim 1, wherein the content of the structural units derived from the aromatic vinyl compound is 45 mass % or less based on the total amount of structural units contained in the modified conjugated diene polymer. The modified conjugated diene polymer according to claim 1, which has a weight average molecular weight measured by gel permeation chromatography of 7.0 × 10 ⁵ or more and 3.0 × 10 ⁶ or less. The modified conjugated diene polymer according to claim 1, in which the molecular weight distribution (Mw/Mn), expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography, is 1.60 or more and 4.00 or less. The modified conjugated diene polymer according to claim 1, wherein the compound (M) includes a compound having two or more hydrocarbyloxysilyl groups. A method for producing the modified conjugated diene polymer according to any one of claims 1 to 6, comprising the steps of:
a polymerization step of polymerizing a monomer containing a conjugated diene compound in the presence of a polymerization initiator to obtain a conjugated diene-based polymer having an active terminal;
a modification step of reacting the conjugated diene polymer having an active end with the compound (M);
A method for producing a modified conjugated diene polymer, comprising the steps of: In the polymerization step, the monomer is polymerized in a solvent in the presence of the polymerization initiator by a continuous polymerization method,
In the modification step, the polymer having an active end is reacted with the compound (M) to obtain a polymer solution,
The method for producing a modified conjugated diene-based polymer according to claim 7, further comprising a desolvation step of removing the solvent from the polymer solution without adding an extender oil to the polymer solution. A rubber veil containing the modified conjugated diene polymer according to any one of claims 1 to 6 and containing no extender oil. The modified conjugated diene polymer according to any one of claims 1 to 6,
At least one filler selected from the group consisting of silica, carbon black, and a compound represented by the following formula (1),
A polymer composition comprising:
nM ¹・mSiO _k・iH ₂ O…(1)
(In formula (1), ^M1 is at least one selected from the group consisting of a specific metal, which is any one of aluminum, magnesium, titanium, zirconium, and calcium, an oxide of the specific metal, a hydroxide of the specific metal, and a carbonate of the specific metal. n is an integer of 1 to 5, m is an integer of 0 to 10, k is an integer of 2 to 5, and i is an integer of 0 to 10.) The polymer composition according to claim 10, further comprising at least one rubber component selected from the group consisting of natural rubber, isoprene rubber, butadiene rubber, emulsion-polymerized styrene-butadiene rubber, solution-polymerized styrene-butadiene rubber, hydrogenated styrene-butadiene rubber, butyl rubber, halogenated butyl rubber, ethylene-propylene rubber, and ethylene-butadiene rubber, which is different from the modified conjugated diene polymer. The polymer composition according to claim 10, further comprising a resin. A crosslinked body obtained by crosslinking the polymer composition according to claim 10. A tire in which one or both of the tread and sidewall are made using the polymer composition described in claim 10.