Stabilized conjugated diene-based polymer

Abstract

Provided is a stabilized conjugated diene-based polymer having excellent Mooney viscosity stability during storage. Provided is a stabilized conjugated diene-based polymer comprising: a conjugated diene-based polymer containing tin atoms and / or silicon atoms; at least two hindered phenol-based stabilizers; and an aromatic amine-based stabilizer.

Description

Stabilized conjugated diene polymer

[0001] The present invention relates to a stabilized conjugated diene-based polymer.

[0002] In recent years, with the growing interest in environmental issues, polymers used in automobile tires are being required to have excellent fuel economy characteristics. Tires obtained using rubber compositions in which silica is blended as a filler with a conjugated diene polymer have improved low heat buildup compared to tires obtained using rubber compositions in which conventionally used carbon black is blended, and therefore can be tires with even more excellent fuel economy characteristics.

[0003] With regard to a conjugated diene polymer for producing such a tire, Patent Document 1 discloses a conjugated diene rubber having a siloxane compound-modified structure at at least one end of a polymer chain containing a conjugated diene monomer unit and a monomer unit of a vinyl compound containing a functional group capable of interacting with silica.

[0004] International Publication No. 2019 / 073829

[0005] The conjugated diene rubber obtained by the technology of Patent Document 1 can give a cross-linked rubber product that is excellent in low heat buildup, wet grip performance and handling stability, and also has excellent processability, but there is room for improvement in Mooney viscosity stability during storage.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a stabilized conjugated diene polymer that has excellent Mooney viscosity stability during storage.

[0007] As a result of intensive research to achieve the above object, the present inventors have found that the above object can be achieved by adding a specific stabilizer in combination to a conjugated diene polymer (A) containing a tin atom and / or a silicon atom, and have thus completed the present invention.

[0008] That is, according to the present invention, the following stabilized conjugated diene polymers are provided. [1] A stabilized conjugated diene polymer comprising a conjugated diene polymer containing a tin atom and / or a silicon atom, two or more types of hindered phenol stabilizers, and an aromatic amine stabilizer. [2] The stabilized conjugated diene polymer according to [1], wherein the conjugated diene polymer contains a tin atom. [3] The stabilized conjugated diene polymer according to [1] or [2], wherein the conjugated diene polymer contains a functional group capable of interacting with silica. [4] The stabilized conjugated diene polymer according to any one of [1] to [3], wherein the conjugated diene polymer contains a unit of a vinyl compound containing a functional group capable of interacting with silica. [5] The stabilized conjugated diene polymer according to [4], wherein the unit of the vinyl compound containing a functional group capable of interacting with silica is a unit represented by the following general formula (3): (In the above general formula (3), X ５ represents a chemical single bond or a hydrocarbylene group, and X ６ , X ７ and X ８each independently represent a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.) [6] The stabilized conjugated diene polymer according to any one of [1] to [5], wherein the total content of the hindered phenol-based stabilizers is 0.01 to 2.00 parts by weight per 100 parts by weight of the conjugated diene-based polymer. [7] The stabilized conjugated diene polymer according to any one of [1] to [6], wherein the content of the aromatic amine-based stabilizer is 0.01 to 2.00 parts by weight per 100 parts by weight of the conjugated diene-based polymer. [8] The stabilized conjugated diene polymer according to any one of [1] to [7], wherein the hindered phenol-based stabilizer (B) includes a hindered phenol-based stabilizer containing a sulfur atom and a hindered phenol-based stabilizer not containing a sulfur atom. [9] The stabilized conjugated diene polymer according to any one of [1] to [8], wherein the hindered phenol stabilizer (B) comprises a semi-hindered phenol stabilizer and a doubly hindered phenol stabilizer.

[10] The stabilized conjugated diene polymer according to any one of [1] to [9], wherein the ratio of the content of the hindered phenol stabilizer (B) to the content of the aromatic amine stabilizer (C) is 10:1 to 0.1:1 in terms of the weight ratio represented by "hindered phenol stabilizer (B):aromatic amine stabilizer (C)."

[0009] Furthermore, according to the present invention, the following rubber composition, cross-linkable rubber composition, cross-linked rubber product, and tire are provided.

[11] A rubber composition containing the stabilized conjugated diene polymer according to any one of [1] to

[10] and a filler.

[12] A cross-linkable rubber composition containing the rubber composition according to

[11] and a cross-linking agent.

[13] A cross-linked rubber product obtained by cross-linking the cross-linkable rubber composition according to

[12] .

[14] A tire comprising the cross-linked rubber product according to

[13] .

[0010] According to the present invention, it is possible to provide a stabilized conjugated diene polymer having excellent Mooney viscosity stability during storage.

[0011] <Stabilized Conjugated Diene Polymer> The stabilized conjugated diene polymer of the present invention is characterized by comprising a conjugated diene polymer containing a tin atom and / or a silicon atom, two or more types of hindered phenol stabilizers, and an aromatic amine stabilizer.

[0012] [Conjugated Diene Polymer (A)] The conjugated diene polymer (A) used in the present invention contains at least a conjugated diene monomer unit as a monomer unit, and also contains a tin atom and / or a silicon atom in the polymer chain.

[0013] The conjugated diene polymer (A) may contain only one of a tin atom and a silicon atom, or may contain both. The conjugated diene polymer (A) preferably contains at least a tin atom, and more preferably contains a tin atom and a silicon atom.

[0014] The tin atom and / or silicon atom contained in the conjugated diene polymer (A) may be derived, for example, from a tin atom-containing coupling agent and / or a silicon atom-containing coupling agent, from a tin atom-containing monomer and / or a silicon atom-containing monomer, or from a tin atom-containing modifier and / or a silicon atom-containing modifier (a modifier for modifying the terminal of a polymer chain).

[0015] When the conjugated diene polymer (A) contains a tin atom, the tin atom contained in the conjugated diene polymer (A) is preferably derived from a tin atom-containing coupling agent, i.e., when the conjugated diene polymer (A) contains a tin atom, the conjugated diene polymer (A) preferably contains a residue of a tin atom-containing coupling agent.

[0016] Examples of the tin atom-containing coupling agent include those containing tin atoms among the coupling agents exemplified in the production method described below, of which tin tetrachloride is preferred.

[0017] Furthermore, when the conjugated diene polymer (A) contains silicon atoms, the silicon atoms contained in the conjugated diene polymer (A) are preferably derived from a silicon-containing coupling agent, a silicon-containing monomer, a silicon-containing modifier, or a combination thereof. That is, when the conjugated diene polymer (A) contains silicon atoms, the conjugated diene polymer (A) preferably contains a residue of a silicon-containing coupling agent, a unit derived from a silicon-containing monomer, a modifying group derived from a silicon-containing modifier, or a combination thereof. Among these, the conjugated diene polymer (A) more preferably contains at least one of a unit derived from a silicon-containing monomer and a modifying group derived from a silicon-containing modifier, even more preferably contains at least a unit derived from a silicon-containing monomer, and particularly preferably contains a unit derived from a silicon-containing monomer and a modifying group derived from a silicon-containing modifier.

[0018] Examples of the silicon-containing coupling agent include those containing silicon atoms among the coupling agents exemplified in the production method described below. Among them, silicon-containing coupling agents are preferably trifunctional or higher functional silicon-containing coupling agents, and more preferably tetrafunctional or higher functional silicon-containing coupling agents.

[0019] Examples of the silicon atom-containing monomer include those containing silicon atoms among the various monomers described below. Among these, vinyl compounds containing a silicon atom-containing functional group are preferred, and compounds represented by general formula (1) are more preferred. When the conjugated diene polymer (A) contains units of a silicon atom-containing monomer, the content of the units of the silicon atom-containing monomer in the conjugated diene polymer (A) is not particularly limited, but is preferably 0.001 to 10.000 wt %, and more preferably 0.001 to 3.000 wt %.

[0020] Examples of the silicon atom-containing modifier include those described below, of which siloxane compounds and hydrocarbyloxysilane compounds are preferred.

[0021] The conjugated diene polymer (A) used in the present invention preferably contains a functional group capable of interacting with silica.

[0022] When the conjugated diene polymer (A) contains a functional group capable of interacting with silica, the functional group is preferably derived from a monomer containing the functional group, a modifier containing the functional group, or a combination thereof. That is, when the conjugated diene polymer (A) contains a functional group capable of interacting with silica, the conjugated diene polymer (A) preferably contains a unit derived from a monomer containing the functional group, a modifying group derived from a modifier containing the functional group, or a combination thereof. Among these, it is more preferable that the conjugated diene polymer (A) contains a unit derived from a monomer containing a functional group capable of interacting with silica. The functional group capable of interacting with silica and the vinyl compound containing a functional group capable of interacting with silica will be described later.

[0023] The conjugated diene polymer (A) used in the present invention contains at least a conjugated diene monomer unit. Examples of conjugated diene compounds for forming the conjugated diene monomer units include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Among these, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. These may be used alone or in combination of two or more.

[0024] The content of the conjugated diene monomer units in the conjugated diene polymer (A) is not particularly limited, but is preferably 30 to 100% by weight, more preferably 35 to 95% by weight, and even more preferably 40 to 90% by weight. By setting the content of the conjugated diene monomer units within the above range, the stabilized conjugated diene polymer can be made to have even better Mooney viscosity stability during storage.

[0025] The vinyl bond content in the conjugated diene monomer units in the conjugated diene polymer (A) is preferably 1 to 90 mol %, more preferably 10 to 80 mol %, even more preferably 20 to 70 mol %, still more preferably 25 to 65 mol %, and particularly preferably 30 to 60 mol %. By setting the vinyl bond content in the conjugated diene monomer units within the above range, the stabilized conjugated diene polymer can be made to have even better Mooney viscosity stability during storage.

[0026] Furthermore, the conjugated diene polymer (A) used in the present invention is preferably a copolymer having aromatic vinyl monomer units in addition to conjugated diene monomer units. Examples of aromatic vinyl monomers for forming the aromatic vinyl monomer units include styrene, methylstyrene, ethylstyrene, t-butylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, chlorostyrene, bromostyrene, methoxystyrene, dimethylaminomethylstyrene, dimethylaminoethylstyrene, diethylaminomethylstyrene, diethylaminoethylstyrene, cyanoethylstyrene, and vinylnaphthalene. Among these, styrene is preferred. These may be used alone or in combination of two or more.

[0027] The content of the aromatic vinyl monomer unit in the conjugated diene polymer (A) is not particularly limited, but is preferably 0 to 70% by weight, more preferably 5 to 65% by weight, and even more preferably 10 to 60% by weight. By setting the content of the aromatic vinyl monomer unit within the above range, the stabilized conjugated diene polymer can be made to have even better Mooney viscosity stability during storage.

[0028] The conjugated diene polymer (A) used in the present invention may contain, in addition to the conjugated diene monomer units and the aromatic vinyl monomer units contained as needed, units of a vinyl compound containing a functional group capable of interacting with silica.

[0029] The vinyl compound containing a functional group capable of interacting with silica to form a unit of the vinyl compound containing a functional group capable of interacting with silica is not particularly limited as long as it is a compound containing a functional group capable of interacting with silica and a vinyl group, and for example, the compounds described in WO 2019 / 073828 can be used.

[0030] Here, a functional group capable of interacting with silica is a functional group that can form a covalent bond between the functional group and the silica surface, or can form an intermolecular force weaker than a covalent bond (for example, ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.). Such functional groups capable of interacting with silica are not particularly limited, but examples include nitrogen atom-containing functional groups, silicon atom-containing functional groups, and oxygen atom-containing functional groups. Among these, silicon atom-containing functional groups are preferred from the viewpoint of their strong interaction with silica.

[0031] As a preferred embodiment of the vinyl compound containing a functional group capable of interacting with silica, a vinyl compound containing a silicon atom-containing functional group may suitably be used, for example, a compound represented by the following general formula (1):

[0032] In the above general formula (1), X １ represents a chemical single bond or a hydrocarbylene group, and X ２ , X ３ and X ４ each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0033] In the above general formula (1), X １is a chemical single bond or a hydrocarbylene group, preferably a chemical single bond. Examples of hydrocarbylene groups include alkylene groups, alkenediyl groups, arylene groups, and groups in which an arylene group and an alkylene group are bonded. Examples of alkylene groups include methylene groups, ethylene groups, and trimethylene groups. Examples of alkenediyl groups include vinylene groups and ethylene-1,1-diyl groups. Examples of arylene groups include phenylene groups, naphthylene groups, and biphenylene groups. Examples of groups in which an arylene group and an alkylene group are bonded include groups in which a phenylene group and a methylene group are bonded, and groups in which a phenylene group and an ethylene group are bonded. X １ When is a hydrocarbylene group, X １ is preferably an arylene group, more preferably a phenylene group.

[0034] In the above general formula (1), X ２ , X ３ and X ４ each independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent. ２ , X ３ and X ４ At least one of X is preferably a substituted amino group; ２ , X ３ and X ４ It is more preferable that two of them are substituted amino groups.

[0035] X ２ , X ３ and X ４ As the substituted amino group which can constitute the above, a group represented by the following general formula (2) is preferred. In the above general formula (2), R １ and R ２ may or may not be bonded to each other, R １ and R ２ When they are not bonded to each other, R １ and R ２each independently represents a hydrocarbyl group or a trihydrocarbylsilyl group which may have a substituent, and R １ and R ２ When R １ and R ２ represents a hydrocarbylene group which may contain at least one atom selected from a nitrogen atom, an oxygen atom, a sulfur atom and a silicon atom.

[0036] R １ and R ２ Examples of hydrocarbyl groups that can constitute R include chain alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, and n-octyl; cyclic alkyl groups such as cyclopentyl and cyclohexyl; and aryl groups such as phenyl, benzyl, and naphthyl. Among these, chain alkyl groups are preferred, and methyl or ethyl groups are more preferred. １ and R ２ When the hydrocarbyl group that can constitute the above has a substituent, examples thereof include hydrocarbyl groups having a hydrocarbyloxy group as the substituent, and examples of the hydrocarbyl group having a hydrocarbyloxy group as the substituent include alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and a methoxyethyl group; and aryloxyalkyl groups such as a phenoxymethyl group.

[0037] R １ and R ２ Specific examples of the trihydrocarbylsilyl group that can constitute the above group include trialkylsilyl groups such as trimethylsilyl group, triethylsilyl group, and tert-butyldimethylsilyl group.

[0038] R １ and R ２ and are bonded to each other, R １ and R ２Examples of the hydrocarbylene group that can constitute R include alkylene groups such as a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, a decamethylene group, a dodecamethylene group, and a 2,2,4-trimethylhexane-1,6-diyl group; and alkenediyl groups such as a pentan-2-ene-1,5-diyl group. １ and R ２ When the hydrocarbylene group that can constitute the above group contains at least one selected from a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom, the hydrocarbylene group containing at least one selected from a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom includes a group represented by -CH=N-CH=CH-, -CH=N-CH ２ -CH ２ a group represented by -, -CH ２ -CH ２ -O-CH ２ -CH ２ a group represented by -, -CH ２ -CH ２ -S-CH ２ -CH ２ a group represented by -, -CH ２ -CH ２ -SiH ２ -CH ２ -CH ２ a group represented by -, -CH ２ -CH ２ -SiMe ２ -CH ２ -CH ２ a group represented by -, -CH ２ -CH ２ -SiEt ２ -CH ２ -CH ２ - and the like.

[0039] R １ and R ２ is an alkyl group, or R １ and R ２ and preferably bond to each other to form an alkylene group, and R １ and R ２ is more preferably an alkyl group, and R １and R ２ is more preferably a methyl group or an ethyl group.

[0040] In the above general formula (2), R １ and R ２ When is a hydrocarbyl group, specific examples of the group represented by general formula (2) above include dialkylamino groups such as dimethylamino group, diethylamino group, ethylmethylamino group, di-n-propylamino group, diisopropylamino group, di-n-butylamino group, diisobutylamino group, di-sec-butylamino group, and di-tert-butylamino group; diarylamino groups such as diphenylamino group; etc. Among these, dialkylamino groups are preferred, and dimethylamino group, diethylamino group, and di-n-butylamino group are more preferred.

[0041] In the above general formula (2), R １ and R ２ is a hydrocarbyl group having a hydrocarbyloxy group as a substituent, specific examples of the group represented by the above general formula (2) include di(alkoxyalkyl)amino groups such as di(methoxymethyl)amino group and di(ethoxymethyl)amino group.

[0042] In the above general formula (2), R １ and R ２ is a trihydrocarbylsilyl group, specific examples of the group represented by the above general formula (2) include trialkylsilyl group-containing amino groups such as a bis(trimethylsilyl)amino group, a bis(tert-butyldimethylsilyl)amino group, and an N-trimethylsilyl-N-methylamino group.

[0043] In the above general formula (2), R １ and R ２and (b) are bonded to each other to form a hydrocarbylene group, specific examples of the group represented by the above general formula (2) include 1-alkyleneimino groups such as a 1-trimethyleneimino group, a 1-pyrrolidino group, a 1-piperidino group, a 1-hexamethyleneimino group, a 1-heptamethyleneimino group, a 1-octamethyleneimino group, a 1-decamethyleneimino group, and a 1-dodecamethyleneimino group.

[0044] In the above general formula (2), R １ and R ２ and are bonded to each other to form a hydrocarbylene group containing a nitrogen atom and / or an oxygen atom, specific examples of the group represented by the above general formula (2) include a 1-imidazolyl group, a 4,5-dihydro-1-imidazolyl group, and a morpholino group.

[0045] As the group represented by the above general formula (2), a dialkylamino group or a 1-alkyleneimino group is preferred, a dialkylamino group is more preferred, and a dimethylamino group, a diethylamino group or a di-n-butylamino group is even more preferred.

[0046] In the above general formula (1), X ２ , X ３ and X ４ Examples of hydrocarbyloxy groups that can constitute the above formula include alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, and tert-butoxy; and aryloxy groups such as phenoxy and benzyloxy.

[0047] In the above general formula (1), X ２ , X ３ and X ４ Examples of hydrocarbyl groups that can constitute X include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl; and aryl groups such as phenyl, 4-methyl-1-phenyl, and benzyl. ２ , X ３ and X ４When the hydrocarbyl group that can constitute the above has a substituent, examples thereof include hydrocarbyl groups having a hydrocarbyloxy group as the substituent, and examples thereof include alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and an ethoxyethyl group.

[0048] In the above general formula (1), X １ is a chemical single bond, and X ２ , X ３ and X ４Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1), in which one of the groups is a substituted amino group, include (dialkylamino)dialkylvinylsilanes such as (dimethylamino)dimethylvinylsilane, (ethylmethylamino)dimethylvinylsilane, (di-n-propylamino)dimethylvinylsilane, (diisopropylamino)dimethylvinylsilane, (dimethylamino)diethylvinylsilane, (ethylmethylamino)diethylvinylsilane, (di-n-propylamino)diethylvinylsilane, and (diisopropylamino)diethylvinylsilane; [bis(trimethylsilyl)amino]dimethylvinylsilane, [bis(t-butyldimethylsilyl)amino]dimethylvinylsilane, [bis(trimethylsilyl)amino]diethylvinylsilane, and [bis(t-butyldimethylsilyl)amino]diethylvinylsilane; (trialkylsilyl)amino]dialkylvinylsilane; (dialkylamino)di(alkoxyalkyl)vinylsilanes such as (dimethylamino)di(methoxymethyl)vinylsilane, (dimethylamino)di(methoxyethyl)vinylsilane, (dimethylamino)di(ethoxymethyl)vinylsilane, (dimethylamino)di(ethoxyethyl)vinylsilane, (diethylamino)di(methoxymethyl)vinylsilane, (diethylamino)di(methoxyethyl)vinylsilane, (diethylamino)di(ethoxymethyl)vinylsilane, and (diethylamino)di(ethoxyethyl)vinylsilane; cyclic aminodialkylvinylsilane compounds such as pyrrolidinodimethylvinylsilane, piperidinodimethylvinylsilane, hexamethyleneiminodimethylvinylsilane, 4,5-dihydroimidazolyldimethylvinylsilane, and morpholinodimethylvinylsilane.

[0049] In the above general formula (1), X １ is a hydrocarbylene group, and X ２ , X ３ and X ４Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1), in which one of the groups is a substituted amino group, include (dimethylamino)dimethyl-4-vinylphenylsilane, (dimethylamino)dimethyl-3-vinylphenylsilane, (diethylamino)dimethyl-4-vinylphenylsilane, (diethylamino)dimethyl-3-vinylphenylsilane, (di-n-propylamino)dimethyl-4-vinylphenylsilane, (di-n-propylamino)dimethyl-3-vinylphenylsilane, (di-n-butylamino)dimethyl-4-vinylphenylsilane, (di-n-butylamino)dimethyl and (dialkylamino)dialkylvinylphenylsilanes such as (dialkylamino)diethyl-3-vinylphenylsilane, (dimethylamino)diethyl-4-vinylphenylsilane, (dimethylamino)diethyl-3-vinylphenylsilane, (diethylamino)diethyl-4-vinylphenylsilane, (diethylamino)diethyl-3-vinylphenylsilane, (di-n-propylamino)diethyl-4-vinylphenylsilane, (di-n-propylamino)diethyl-3-vinylphenylsilane, (di-n-butylamino)diethyl-4-vinylphenylsilane, and (di-n-butylamino)diethyl-3-vinylphenylsilane.

[0050] In the above general formula (1), X １ is a chemical single bond, and X ２ , X ３ and X ４Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1), in which two of the groups are substituted amino groups, include bis(dialkylamino)alkylvinylsilanes such as bis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane, bis(di-n-propylamino)methylvinylsilane, bis(di-n-butylamino)methylvinylsilane, bis(dimethylamino)ethylvinylsilane, bis(diethylamino)ethylvinylsilane, bis(di-n-propylamino)ethylvinylsilane, and bis(di-n-butylamino)ethylvinylsilane; bis[bis(trimethylsilyl)amino]methylvinylsilane, bis[bis(tert-butyldimethylsilyl)amino]methylvinylsilane, bis[bis(trimethylsilyl)amino]ethylvinylsilane, and bis[bis(tert-butyldimethylsilyl)amino]ethylvinylsilane. bis(dialkylamino)alkoxyalkylsilanes such as bis(dimethylamino)methoxymethylvinylsilane, bis(dimethylamino)methoxyethylvinylsilane, bis(dimethylamino)ethoxymethylvinylsilane, bis(dimethylamino)ethoxyethylvinylsilane, bis(diethylamino)methoxymethylvinylsilane, bis(diethylamino)methoxyethylvinylsilane, bis(diethylamino)ethoxymethylvinylsilane, and bis(dimethylamino)ethoxyethylvinylsilane; bis(cyclic amino)alkylvinylsilane compounds such as bis(pyrrolidino)methylvinylsilane, bis(piperidino)methylvinylsilane, bis(hexamethyleneimino)methylvinylsilane, bis(4,5-dihydroimidazolyl)methylvinylsilane, and bis(morpholino)methylvinylsilane; and the like.

[0051] In the above general formula (1), X １ is a hydrocarbylene group, and X ２ , X ３ and X ４Specific examples of vinyl compounds containing silicon atom-containing functional groups represented by the above general formula (1) when two of them are substituted amino groups include bis(dimethylamino)methyl-4-vinylphenylsilane, bis(dimethylamino)methyl-3-vinylphenylsilane, bis(diethylamino)methyl-4-vinylphenylsilane, bis(diethylamino)methyl-3-vinylphenylsilane, bis(di-n-propylamino)methyl-4-vinylphenylsilane, bis(di-n-propylamino)methyl-3-vinylphenylsilane, bis(di-n-butylamino)methyl-4-vinylphenylsilane, bis(di-n-butylamino)methyl and bis(dialkylamino)alkylvinylphenylsilanes such as bis(dimethylamino)ethyl-3-vinylphenylsilane, bis(dimethylamino)ethyl-4-vinylphenylsilane, bis(dimethylamino)ethyl-3-vinylphenylsilane, bis(diethylamino)ethyl-4-vinylphenylsilane, bis(diethylamino)ethyl-3-vinylphenylsilane, bis(di-n-propylamino)ethyl-4-vinylphenylsilane, bis(di-n-propylamino)ethyl-3-vinylphenylsilane, bis(di-n-butylamino)ethyl-4-vinylphenylsilane, and bis(di-n-butylamino)ethyl-3-vinylphenylsilane.

[0052] In the above general formula (1), X １ is a chemical single bond, and X ２ , X ３ and X ４ Specific examples of vinyl compounds containing silicon atom-containing functional groups represented by the above general formula (1) in the case where three of the groups are substituted amino groups include tris(dialkylamino)vinylsilanes such as tris(dimethylamino)vinylsilane, tris(diethylamino)vinylsilane, tris(di-n-propylamino)vinylsilane, and tris(di-n-butylamino)vinylsilane.

[0053] In the above general formula (1), X １ is a hydrocarbylene group, and X ２ , X ３ and X ４Specific examples of vinyl compounds containing silicon atom-containing functional groups represented by general formula (1) above, in the case where three of the groups are substituted amino groups, include tris(dialkylamino)vinylphenylsilanes such as tris(dimethylamino)-4-vinylphenylsilane, tris(dimethylamino)-3-vinylphenylsilane, tris(diethylamino)-4-vinylphenylsilane, tris(diethylamino)-3-vinylphenylsilane, tris(di-n-propylamino)-4-vinylphenylsilane, tris(di-n-propylamino)-3-vinylphenylsilane, tris(di-n-butylamino)-4-vinylphenylsilane, and tris(di-n-butylamino)-3-vinylphenylsilane.

[0054] In the above general formula (1), X １ is a chemical single bond, and X ２ , X ３ and X ４ Among these, specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1), when none of them is a substituted amino group, include trialkoxyvinylsilanes such as trimethoxyvinylsilane, triethoxyvinylsilane, tripropoxyvinylsilane, etc.; dialkoxyalkylvinylsilanes such as methyldimethoxyvinylsilane, methyldiethoxyvinylsilane, etc.; dialkoxyarylvinylsilanes such as di(tert-pentoxy)phenylvinylsilane, di(tert-butoxy)phenylvinylsilane, etc.; monoalkoxydialkylvinylsilanes such as dimethylmethoxyvinylsilane; monoalkoxydiarylvinylsilanes such as tert-butoxydiphenylvinylsilane, tert-pentoxydiphenylvinylsilane, etc.; monoalkoxyalkylarylvinylsilanes such as tert-butoxymethylphenylvinylsilane, tert-butoxyethylphenylvinylsilane, etc.; and substituted alkoxyvinylsilane compounds such as tris(β-methoxyethoxy)vinylsilane.

[0055] Among the compounds represented by the general formula (1), X １ is preferably a chemical single bond, and X １is a chemical single bond, and X ２ , X ３ and X ４ Among these, compounds in which two are substituted amino groups are more preferred, １ is a chemical single bond, and X ２ , X ３ and X ４ Among these, compounds in which two of the groups are dialkylamino groups are particularly preferred.

[0056] Among the compounds represented by the general formula (1), bis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane, and bis(di-n-butylamino)methylvinylsilane are preferred, with bis(diethylamino)methylvinylsilane being particularly preferred.

[0057] Furthermore, examples of vinyl compounds containing a functional group capable of interacting with silica other than the compound represented by the general formula (1) above include bis(trialkylsilyl)aminostyrenes such as 4-N,N-bis(trimethylsilyl)aminostyrene and 3-N,N-bis(trimethylsilyl)aminostyrene; and bis(trialkylsilyl)aminoalkylstyrenes such as 4-bis(trimethylsilyl)aminomethylstyrene, 3-bis(trimethylsilyl)aminomethylstyrene, 4-bis(trimethylsilyl)aminoethylstyrene, and 3-bis(trimethylsilyl)aminoethylstyrene.

[0058] When the compound represented by the general formula (1) is used as the vinyl compound containing a functional group capable of interacting with silica, a unit represented by the following general formula (3) is introduced into the conjugated diene polymer (A) as a unit of the vinyl compound containing a functional group capable of interacting with silica. In the above general formula (3), X ５ represents a chemical single bond or a hydrocarbylene group, and X ６ , X ７ and X ８ each independently represents a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0059] In the unit represented by the general formula (3), X ５ represents X in the compound represented by the general formula (1). １ In the unit represented by the general formula (3), X ６ , X ７ and X ８ represents X in the compound represented by the general formula (1). ２ , X ３ and X ４ Therefore, in the unit represented by the general formula (3), X ５ , X ６ , X ７ and X ８ represents X in the compound represented by the general formula (1). １ , X ２ , X ３ and X ４ In addition, the compound represented by the general formula (1) may be the same as X ２ , X ３ and X ４ In the case where at least one of X is a substituted amino group or a hydrocarbyloxy group, the substituted amino group or the hydrocarbyloxy group can be hydrolyzed in any step and at any timing to form X ２ , X ３ and X ４ At least one of the groups may be a hydroxyl group.

[0060] The content of the vinyl compound unit containing a functional group capable of interacting with silica in the conjugated diene polymer (A) is preferably 0.001 to 10,000% by weight, and more preferably 0.001 to 3,000% by weight, based on 100% by weight of the total amount of all monomers.

[0061] Furthermore, the conjugated diene polymer (A) may contain other monomer units in addition to the above-mentioned monomer units. Examples of other compounds constituting such other monomer units include α,β-unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids or acid anhydrides such as acrylic acid, methacrylic acid, and maleic anhydride; unsaturated carboxylic acid esters such as methyl methacrylate, ethyl acrylate, and butyl acrylate; chain olefin compounds such as ethylene, propylene, and 1-butene; cyclic olefin compounds such as cyclopentene and 2-norbornene; and non-conjugated dienes such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene. These may be used alone or in combination of two or more.

[0062] The content of other monomer units in the conjugated diene polymer (A) is preferably 10% by weight or less, more preferably 5% by weight or less, based on 100% by weight of the total amount of all monomers.

[0063] When the conjugated diene polymer (A) is composed of two or more types of monomer units, the bonding pattern of each monomer unit may be various bonding patterns such as block, tapered, random, etc., but a random bonding pattern is preferred. By using a random bonding pattern, the fuel economy of the resulting cross-linked rubber can be improved.

[0064] The conjugated diene polymer (A) used in the present invention preferably contains a modifying group obtained by modifying the terminal of the polymer chain with a modifying agent.

[0065] The modifying group preferably contains a functional group capable of interacting with silica, from the viewpoint of appropriately increasing affinity for fillers such as silica and improving the strength, abrasion resistance, and fuel economy of the resulting cross-linked rubber. Here, the functional group capable of interacting with silica is a functional group capable of forming a covalent bond between the functional group and the silica surface, or of forming an intermolecular force weaker than a covalent bond (for example, ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.). Such functional groups capable of interacting with silica are not particularly limited, but include nitrogen-atom-containing functional groups, silicon-atom-containing functional groups, and oxygen-atom-containing functional groups.

[0066] As the modifier for forming the modifying group, from the viewpoint of high interaction with silica, a silicon atom-containing modifier having a silicon atom-containing functional group and a nitrogen atom-containing modifier having a nitrogen atom-containing functional group are preferred, and a silicon atom-containing modifier is more preferred. Examples of the silicon atom-containing modifier include a siloxane compound and a hydrocarbyloxysilane compound.

[0067] The hydrocarbyloxysilane compound is more preferably a hydrocarbyloxysilane compound having an amino group, and examples thereof include [3-(dimethylamino)propyl]trimethoxysilane, [3-(diethylamino)propyl]trimethoxysilane, [3-(dimethylamino)propyl]triethoxysilane, [3-(diethylamino)propyl]triethoxysilane, [3-(ethylmethylamino)propyl]trimethoxysilane, [3-(ethylmethylamino)propyl]triethoxysilane, and [3-(dimethylamino)propyl]methyldimethoxysilane. Silane, [3-(diethylamino)propyl]methyldimethoxysilane, [3-(dimethylamino)propyl]ethyldimethoxysilane, [3-(diethylamino)propyl]ethyldimethoxysilane, [(3-methyl-3-ethylamino)propyl]methyldimethoxysilane, [(3-methyl-3-ethylamino)propyl]ethyldimethoxysilane, [3-(dimethylamino)propyl]methyldiethoxysilane, [3-(diethylamino)propyl]methyldiethoxysilane, [3-(dimethylamino)propyl]ethyldiethoxysilane, [3- (diethylamino)propyl]ethyldiethoxysilane, [3-(ethylmethylamino)propyl]methyldiethoxysilane, [3-(ethylmethylamino)propyl]ethyldiethoxysilane, [3-(benzylmethylamino)propyl]trimethoxysilane, [3-(benzylmethylamino)propyl]triethoxysilane, {3-[di(methoxymethyl)amino]propyl}trimethoxysilane, {3-[di(methoxyethyl)amino]propyl}trimethoxysilane, {3-[di(methoxymethyl)amino]propyl}triethoxysilane, 3-[di(methoxyethyl)amino]propyl}triethoxysilane, {3-[di(ethoxyethyl)amino]propyl}trimethoxysilane, {3-[di(ethoxymethyl)amino]propyl}trimethoxysilane, {3-[di(ethoxyethyl)amino]propyl]triethoxysilane, {3-[di(ethoxymethyl)amino]propyl}triethoxysilane, {3-[N,N-bis(trimethylsilyl)amino]propyl}trimethoxysilane, {3-[N,N-bis(trimethylsilyl)amino]propyl}triethoxysilane, {3-[N,N-bis(t-butyldimethylsilyl)amino]propyl}trimethoxysilane, {3-[N,N-bis(t-butyldimethylsilyl)amino]propyl}triethoxysilane, {3-[N,N-bis(trimethylsilyl)amino]propyl}methyldimethoxysilane, {3-[N,N-bis(trimethylsilyl)amino]propyl}methyldiethoxysilane, {3-[N,N-bis(t-butyldimethylsilyl)amino]propyl}methyldimethoxysilane, {3-[N,N-bis(t-butyldimethylsilyl)amino]propyl}methyldimethoxysilane, Examples include {3-(ethyldimethylsilyl)amino]propyl}methyldiethoxysilane, [3-(ethylmethylamino)propyl]trimethoxysilane, [3-(ethylmethylamino)propyl]triethoxysilane, [3-(ethylmethylamino)propyl]methyldimethoxysilane, [3-(ethylmethylamino)propyl]ethyldimethoxysilane, [3-(ethylmethylamino)propyl]methyldiethoxysilane, and [3-(ethylmethylamino)propyl]ethyldiethoxysilane. Among these, [3-(dimethylamino)propyl]trimethoxysilane, [3-(diethylamino)propyl]trimethoxysilane, [3-(dimethylamino)propyl]triethoxysilane, and [3-(diethylamino)propyl]triethoxysilane are preferably used.

[0068] Examples of the nitrogen atom-containing modifying agent include N,N-disubstituted aminoalkyl(meth)acrylamides such as dimethylaminoethyl acrylamide, diethylaminoethyl acrylamide, dimethylaminopropyl acrylamide, diethylaminopropyl acrylamide, dimethylaminobutyl acrylamide, diethylaminobutyl acrylamide, dimethylaminoethyl methacrylamide, diethylaminoethyl methacrylamide, dimethylaminopropyl methacrylamide, diethylaminopropyl methacrylamide, dimethylaminobutyl methacrylamide, and diethylaminobutyl methacrylamide. imides; amino group-containing alkoxysilane compounds such as [3-(dimethylamino)propyl]trimethoxysilane, [3-(diethylamino)propyl]trimethoxysilane, [3-(dimethylamino)propyl]triethoxysilane, [3-(diethylamino)propyl]triethoxysilane, [3-(ethylmethylamino)propyl]trimethoxysilane, and [3-(ethylmethylamino)propyl]triethoxysilane; and pyrrolidone compounds such as N-phenyl-2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and 1-cyclohexyl-2-pyrrolidone.

[0069] The siloxane compound is not particularly limited as long as it has a siloxane structure (—Si—O—) as a main chain structure, but an organosiloxane having an organic group on the side chain is preferred, and a polyorganosiloxane represented by the following general formula (4) is more preferred.

[0070] In the above general formula (4), R ３ ~R １０ represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, which may be the same or different. ９ and X １２ is any group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group-containing group having 4 to 12 carbon atoms, and these may be the same or different. １０is an alkoxy group having 1 to 5 carbon atoms or a group containing an epoxy group and having 4 to 12 carbon atoms, and X １０ When there are a plurality of X, they may be the same or different. １１ is a group containing 2 to 20 repeating alkylene glycol units, and X １１ When there are a plurality of m, they may be the same or different. m is an integer of 0 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m+n+k is 1 or more.

[0071] In the polyorganosiloxane represented by the general formula (4), R ３ ~R １０ , X ９ and X １２ Examples of alkyl groups having 1 to 6 carbon atoms that can constitute the above include methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, and cyclohexyl groups. Examples of aryl groups having 6 to 12 carbon atoms include phenyl and methylphenyl groups. Among these, methyl and ethyl groups are preferred from the viewpoint of ease of production of the polyorganosiloxane itself.

[0072] In addition, in the polyorganosiloxane represented by the general formula (4), X ９ , X １０ and X １２ Examples of the alkoxy group having 1 to 5 carbon atoms that can constitute the above include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group. Among these, from the viewpoint of ease of production of the polyorganosiloxane itself, a methoxy group and an ethoxy group are preferred.

[0073] Furthermore, in the polyorganosiloxane represented by the general formula (4), X ９ , X １０ and X １２ Examples of the epoxy group-containing group having 4 to 12 carbon atoms that can constitute the above formula include groups represented by the following general formula (5): １ -Z ２ -E １(5) In the above general formula (5), Z １ is an alkylene group or alkylarylene group having 1 to 10 carbon atoms, and Z ２ is a methylene group, a sulfur atom, or an oxygen atom, and E １ is a hydrocarbon group having 2 to 10 carbon atoms and having an epoxy group.

[0074] The group represented by the general formula (5) includes Z ２ is preferably an oxygen atom, and Z ２ is an oxygen atom, and E １ is more preferably a glycidyl group, and Z １ is an alkylene group having 1 to 3 carbon atoms, and Z ２ is an oxygen atom, and E １ is a glycidyl group is particularly preferred.

[0075] In addition, in the polyorganosiloxane represented by the general formula (4), X ９ and X １２ Among the above, X is preferably a group containing an epoxy group and having 4 to 12 carbon atoms, or an alkyl group having 1 to 6 carbon atoms. １０ Among the above, an epoxy group-containing group having 4 to 12 carbon atoms is preferred as X. ９ and X １２ is an alkyl group having 1 to 6 carbon atoms, and X １０ is more preferably a group containing an epoxy group and having 4 to 12 carbon atoms.

[0076] In addition, in the polyorganosiloxane represented by the general formula (4), X １１ That is, the group containing 2 to 20 repeating units of alkylene glycol is preferably a group represented by the following general formula (6): In the general formula (6), a is an integer of 2 to 20, and X １３ is an alkylene group or alkylarylene group having 2 to 10 carbon atoms, and R １１ is a hydrogen atom or a methyl group, and X １４ is an alkoxy group or an aryloxy group having 1 to 10 carbon atoms. Among these, a is an integer of 2 to 8, and X １３is an alkylene group having 3 carbon atoms, and R １１ is a hydrogen atom, and X １４ is preferably a methoxy group.

[0077] In the polyorganosiloxane represented by the general formula (4), m is an integer of 0 to 200, preferably an integer of 20 to 150, and more preferably an integer of 30 to 120. When m is 200 or less, the polyorganosiloxane represented by the general formula (4) itself is easier to produce, and its viscosity does not become too high, making it easier to handle.

[0078] In the polyorganosiloxane represented by the general formula (4), n is an integer of 0 to 200, preferably an integer of 0 to 150, and more preferably an integer of 0 to 120. k is an integer of 0 to 200, preferably an integer of 0 to 150, and more preferably an integer of 0 to 130. The total number of m, n, and k is 1 or more, preferably 2 to 400, more preferably 20 to 300, and particularly preferably 30 to 250. When the total number of m, n, and k is 1 or more, the reaction between the polyorganosiloxane represented by the general formula (4) and the active terminal of the conjugated diene polymer in the production process of the conjugated diene polymer (A) is facilitated. Furthermore, when the total number of m, n, and k is 400 or less, the polyorganosiloxane represented by the general formula (4) itself is easily produced, and its viscosity does not become too high, making it easy to handle.

[0079] As a modifying agent for forming a modifying group, a nitrogen atom-containing modifying agent having a nitrogen atom-containing functional group may be used, for example, a hydrocarbyloxysilane compound containing a nitrogen atom may be used.

[0080] The nitrogen atom-containing hydrocarbyloxysilane compound is a silicon-containing compound having at least one nitrogen atom-containing group and one hydrocarbyloxy group. Such a nitrogen atom-containing hydrocarbyloxysilane compound is not particularly limited, but the compounds described in WO 2019 / 189204 can be used.

[0081] As the hydrocarbyloxysilane compound containing a nitrogen atom, for example, a compound represented by the following general formula (7) can be suitably used.

[0082] In the above general formula (7), R ３ is a hydrocarbyl group, A １ is a hydrocarbyloxy group, and A ２ is a group containing a nitrogen atom, p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p+q+r=4. ２ The nitrogen atom-containing group represented by the formula (I) may be a group containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom, or may be a nitrogen atom-containing group other than these.

[0083] Furthermore, as the hydrocarbyloxysilane compound containing a nitrogen atom, a compound represented by the following general formula (8) can also be suitably used.

[0084] In the above general formula (8), A ３ is a hydrocarbyloxy group, and R ４ represents a hydrocarbon group which may have a substituent, and R ５ and R ６ each independently represents a hydrocarbon group which may have a substituent, R ５ and R ６ may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, and when forming such a ring structure, they may form a ring structure together with the nitrogen atom to which they are bonded and a heteroatom other than the nitrogen atom to which they are bonded. s is an integer of 0 to 2.

[0085] In addition, it is also preferable to use a carbonyl group-containing compound containing a nitrogen atom as the nitrogen atom-containing modifier. The carbonyl group-containing compound containing a nitrogen atom is a compound having at least one group containing a nitrogen atom and one carbonyl group, and the carbonyl group-containing compound containing a nitrogen atom is not particularly limited, but a compound represented by the following general formula (9) can be preferably used.

[0086] In the above general formula (9), R ８ , R ９ each independently represents a hydrocarbyl group which may have a substituent, R １０ represents a hydrocarbylene group, R １１ represents a hydrocarbyl group which may have a substituent, or a hydrogen atom. ４ is a chemical single bond, an oxygen atom, or -NR １２ - (R １２ represents a hydrocarbyl group or a hydrogen atom. ８ , R ９ may be partly bonded to each other to form a hydrocarbylene group which may have a nitrogen atom and / or an oxygen atom. １１ is part of R ８ or R ９ may bond to a part of the above to form a hydrocarbylene group which may have a nitrogen atom and / or an oxygen atom.

[0087] R ８ , R ９ , R １１ The optionally substituted hydrocarbyl group in the formula (I) is a hydrocarbyl group or a substituted hydrocarbyl group. Examples of the substituted hydrocarbyl group include a hydrocarbyl group substituted with a hydrocarbyloxy group and a hydrocarbyl group substituted with a substituted amino group.

[0088] Examples of hydrocarbyl groups include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, and aralkyl groups. The alkyl group is preferably an alkyl group having 1 to 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-dodecyl, cyclopentyl, and cyclohexyl. The alkenyl group is preferably an alkenyl group having 2 to 12 carbon atoms, such as vinyl, allyl, 1-propenyl, and isopropenyl. The alkynyl group is preferably an alkynyl group having 2 to 12 carbon atoms, such as ethynyl and 2-propynyl. The aryl group is preferably an aryl group having 6 to 12 carbon atoms, such as a phenyl group, a methylphenyl group, an ethylphenyl group, a benzyl group, a tolyl group, a xylyl group, etc. The aralkyl group is preferably an aralkyl group having 7 to 13 carbon atoms, such as a benzyl group.

[0089] Examples of hydrocarbyl groups substituted with hydrocarbyloxy groups include alkoxyalkyl groups such as methoxymethyl, ethoxymethyl, and ethoxyethyl groups.

[0090] Examples of the hydrocarbyl group substituted with a substituted amino group include (N,N-dialkylamino)alkyl groups such as an N,N-dimethylaminomethyl group, a 2-(N,N-dimethylamino)ethyl group, a 2-(N,N-diethylamino)ethyl group, a 3-(N,N-dimethylamino)propyl group, and a 3-(N,N-diethylamino)propyl group; (N,N-dialkylamino)aryl groups such as a 4-(N,N-dimethylamino)phenyl group, a 3-(N,N-dimethylamino)phenyl group, a 4-(N,N-diethylamino)phenyl group, and a 3-(N,N-diethylamino)phenyl group; alkyl groups substituted with a cyclic amino group such as a 3-(1-pyrrolidinyl)propyl group, a 3-(1-piperidinyl)propyl group, or a 3-(1-imidazolyl)propyl group; aryl groups substituted with a cyclic amino group such as a 4-(1-pyrrolidinyl)phenyl group, a 4-(1-piperidinyl)phenyl group, or a 4-(1-imidazolyl)phenyl group; and alkylaryl groups substituted with a cyclic amino group such as a 4-[2-(1-pyrrolidinyl)ethyl]phenyl group, a 4-[2-(1-piperidinyl)ethyl]phenyl group, or a 4-[2-(1-imidazolyl)ethyl]phenyl group.

[0091] R １０ Examples of the hydrocarbylene group as the alkylene group include an alkylene group, an alkenediyl group, an arylene group, and an arylene-alkylene group. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, and a 2,2,4-trimethylhexane-1,6-diyl group. Examples of the alkenediyl group include a pentan-2-ene-1,5-diyl group. Examples of the arylene group include a phenylene group, a naphthylene group, and a biphenylene group. Examples of the arylene-alkylene group include a phenylene-alkylene group, a naphthylene-alkylene group, and a biphenylene-alkylene group.

[0092] In the above general formula (9), A ４ is a chemical single bond, an oxygen atom, or -NR １２ - (R １２ represents a hydrocarbyl group or a hydrogen atom; ４ represents an oxygen atom or -NR １２ - (R １２ represents a hydrocarbylene group having from 1 to 5 carbon atoms or a hydrogen atom.) is preferred, an oxygen atom or a group represented by —NH— is more preferred, and a group represented by —NH— is even more preferred.

[0093] The compound represented by the general formula (9) includes A ４ is an oxygen atom, for example, 2-(dihydrocarbylamino)ethyl acrylates such as 2-(dimethylamino)ethyl acrylate and 2-(diethylamino)ethyl acrylate; 3-(dihydrocarbylamino)propyl acrylates such as 3-(dimethylamino)propyl acrylate; 2-(dihydrocarbylamino)ethyl methacrylates such as 2-(dimethylamino)ethyl methacrylate and 2-(diethylamino)ethyl methacrylate; 3-(dihydrocarbylamino)propyl methacrylates such as 3-(dimethylamino)propyl methacrylate; and the like.

[0094] In addition, the compound represented by the general formula (9) includes A ４ Ga-NR １２ - (R １２represents a hydrocarbyl group or a hydrogen atom. Examples of the compound in which N-(2-dihydrocarbylaminoethyl)methacrylamides such as N-(3-dimethylaminopropyl)methacrylamide and N-(3-diethylaminopropyl)methacrylamide; N-(3-dihydrocarbylaminopropyl)methacrylamides such as N-(3-dimethylaminopropyl)methacrylamide and N-(3-diethylaminopropyl)methacrylamide; and N-(4-dihydrocarbylaminobutyl)methacrylamides such as N-(4-dimethylaminobutyl)methacrylamide and N-(4-diethylaminobutyl)methacrylamide. Of these, N-(3-dihydrocarbylaminopropyl)acrylamide is preferred, and N-(3-dimethylaminopropyl)acrylamide is more preferred.

[0095] The weight average molecular weight (Mw) of the conjugated diene polymer (A) used in the present invention is not particularly limited, but is preferably 50,000 to 5,000,000, more preferably 75,000 to 3,000,000, and particularly preferably 100,000 to 1,000,000, as measured by gel permeation chromatography in terms of polystyrene. By setting the weight average molecular weight (Mw) of the conjugated diene polymer (A) within the above range, the stabilized conjugated diene polymer can be made to have even better Mooney viscosity stability during storage.

[0096] The molecular weight distribution of the conjugated diene polymer (A) used in the present invention, represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.1 to 3.0, more preferably 1.2 to 2.5, and particularly preferably 1.2 to 2.2. By adjusting the molecular weight distribution (Mw / Mn) of the conjugated diene polymer (A) to fall within the above range, the stabilized conjugated diene polymer can be made to have even more excellent Mooney viscosity stability during storage.

[0097] The Mooney viscosity (ML1+4, 100°C) of the conjugated diene polymer (A) used in the present invention is not particularly limited, but is preferably 10 to 200, more preferably 15 to 150, even more preferably 20 to 100, and particularly preferably 25 to 80. By setting the Mooney viscosity within the above range, the stabilized conjugated diene polymer can be made to have even better Mooney viscosity stability during storage. The Mooney viscosity (ML1+4, 100°C) is measured in accordance with JIS K6300.

[0098] The glass transition temperature (Tg) of the conjugated diene polymer (A) used in the present invention is not particularly limited, but is preferably −100° C. to 20° C., more preferably −70° C. to 10° C. The glass transition temperature of the conjugated diene polymer (A) used in the present invention can be appropriately adjusted, for example, by adjusting the content of aromatic vinyl monomer units in the conjugated diene polymer (A) and the vinyl bond content in the conjugated diene monomer units.

[0099] [Hindered Phenol-Based Stabilizer (B)] The hindered phenol-based stabilizer (B) used in the present invention is a stabilizer added to the conjugated diene-based polymer (A).

[0100] The hindered phenol stabilizer (B) is a stabilizer composed of a phenolic compound having a phenol structure (i.e., a structure having a benzene ring and an OH group bonded to the benzene ring) and a hindered group at at least one of the 2- and 6-positions of the OH group (phenolic hydroxyl group) constituting the phenol structure. The hindered group may be any bulky group, and examples thereof include substituents having 4 or more carbon atoms. Specific examples of the hindered group include tertiary alkyl groups such as t-butyl, t-pentyl, and t-hexyl; secondary alkyl groups such as sec-butyl and sec-pentyl; branched primary alkyl groups such as i-butyl and i-pentyl; cycloalkyl groups such as cyclohexyl and cyclopentyl; and alkyl groups in which alkylthio groups are substituted so that the total number of carbon atoms is 4 or more, such as octylthio and octylthiomethyl.

[0101] Examples of the hindered phenol stabilizer (B) include a hindered phenol stabilizer containing a sulfur atom and a hindered phenol stabilizer not containing a sulfur atom. As the hindered phenol stabilizer (B), it is preferable to use at least a hindered phenol stabilizer containing a sulfur atom.

[0102] Examples of sulfur atom-containing hindered phenol stabilizers include 2,4-bis[(octylthio)methyl]-o-cresol, 2,4-bis[(dodecylthio)methyl]-o-cresol, 4,4'-butylidenebis-(3-methyl-6-tert-butylphenol), 2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine, and 2,2-thio-diethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Of these, 2,4-bis[(octylthio)methyl]-o-cresol is preferred. These may be used alone or in combination of two or more.

[0103] Examples of sulfur-free hindered phenol stabilizers include poly(oxy-1,2-ethanediyl)-alpha-[3-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1-oxopropyl]-omega-[3-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1-oxopropoxy], octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamate, and 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid C7-C9-branched alkyl esters. Examples of suitable hydroxybenzoates include 4,4'-butylidenebis-(3-methyl-6-tert-butylphenol), 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid octadecyl ester, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], and tris-(3,5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate. Among these, octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamate is preferred. These may be used alone or in combination of two or more.

[0104] Examples of the hindered phenol stabilizer (B) include a doubly hindered phenol stabilizer, a semi-hindered phenol stabilizer, a less hindered phenol stabilizer, etc. As the hindered phenol stabilizer (B), it is preferable to use at least a semi-hindered phenol stabilizer.

[0105] Here, the doubly hindered phenol stabilizer is a phenol stabilizer in which both the 2- and 6-positions (i.e., two ortho-positions) of the OH group (phenolic hydroxyl group) constituting the phenol structure are hindered groups. The semi-hindered phenol stabilizer is a phenol stabilizer in which one of the 2- and 6-positions of the OH group (phenolic hydroxyl group) constituting the phenol structure is a hindered group, and the other is an alkyl group having 3 or less carbon atoms, such as a methyl group (preferably a methyl group). The less-hindered phenol stabilizer is a phenol stabilizer in which one of the 2- and 6-positions of the OH group (phenolic hydroxyl group) constituting the phenol structure is a hindered group, and the other is a hydrogen atom.

[0106] The stabilized conjugated diene polymer of the present invention contains two or more types of hindered phenol-based stabilizers (B). In one embodiment of the present invention, the stabilized conjugated diene polymer preferably contains, as the hindered phenol-based stabilizer (B), one or more types of sulfur-atom-containing hindered phenol-based stabilizers and one or more types of sulfur-atom-free hindered phenol-based stabilizers. Also, in one embodiment of the present invention, the stabilized conjugated diene polymer preferably contains, as the hindered phenol-based stabilizer (B), one or more types of semi-hindered phenol-based stabilizers and one or more types of doubly hindered phenol-based stabilizers.

[0107] The total content of the two or more types of hindered phenol-based stabilizers (B) is not particularly limited, but is preferably 0.01 to 2.00 parts by weight, more preferably 0.10 to 1.00 parts by weight, and even more preferably 0.20 to 0.80 parts by weight, relative to 100 parts by weight of the conjugated diene-based polymer (A).

[0108] When the stabilized conjugated diene polymer contains a hindered phenol stabilizer containing a sulfur atom, the content of the hindered phenol stabilizer containing a sulfur atom is preferably 0.01 to 1.00 parts by weight, more preferably 0.05 to 0.50 parts by weight, and even more preferably 0.10 to 0.30 parts by weight, per 100 parts by weight of the conjugated diene polymer (A).

[0109] When the stabilized conjugated diene polymer contains a hindered phenol stabilizer that does not contain a sulfur atom, the content of the hindered phenol stabilizer that does not contain a sulfur atom is preferably 0.01 to 1.00 parts by weight, more preferably 0.10 to 0.80 parts by weight, and even more preferably 0.20 to 0.60 parts by weight, per 100 parts by weight of the conjugated diene polymer (A).

[0110] When the stabilized conjugated diene polymer contains a hindered phenol stabilizer containing a sulfur atom and a hindered phenol stabilizer not containing a sulfur atom, the ratio of their contents, expressed as a weight ratio of "hindered phenol stabilizer containing a sulfur atom:hindered phenol stabilizer not containing a sulfur atom", is preferably 1:10 to 1:0.1, more preferably 1:5 to 1:0.5, and even more preferably 1:3 to 1:1.

[0111] When the stabilized conjugated diene polymer contains a semi-hindered phenol-based stabilizer, the content of the semi-hindered phenol-based stabilizer is preferably 0.01 to 1.00 parts by weight, more preferably 0.05 to 0.50 parts by weight, and even more preferably 0.10 to 0.30 parts by weight, relative to 100 parts by weight of the conjugated diene polymer (A).

[0112] When the stabilized conjugated diene polymer contains a doubly hindered phenol-based stabilizer, the content of the doubly hindered phenol-based stabilizer is preferably 0.01 to 1.00 parts by weight, more preferably 0.10 to 0.80 parts by weight, and even more preferably 0.20 to 0.60 parts by weight, relative to 100 parts by weight of the conjugated diene polymer (A).

[0113] When the stabilized conjugated diene polymer contains a semi-hindered phenol stabilizer and a double-hindered phenol stabilizer, the ratio of their contents, expressed as a weight ratio of "semi-hindered phenol stabilizer:double-hindered phenol stabilizer", is preferably 1:10 to 1:0.1, more preferably 1:5 to 1:0.5, and even more preferably 1:3 to 1:1.

[0114] [Aromatic Amine Stabilizer (C)] The aromatic amine stabilizer (C) used in the present invention is a stabilizer added to the conjugated diene polymer (A).

[0115] Specific examples of the aromatic amine stabilizer (C) include N,N'-di-sec-butyl-1,4-phenylenediamine, a reaction product of N-phenylbenzenamine and 2,4,4-trimethylpentene, bis(4-octylphenyl)amine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, N,N'-di-2-naphthyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine, N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine, and N,N'-bis(methyl-phenyl)-1,4-benzenediamine. A more preferred aromatic amine stabilizer (C) is a reaction product of N-phenylbenzenamine and 2,4,4-trimethylpentene.

[0116] The content of the aromatic amine-based stabilizer (C) used in the present invention is not particularly limited, but is preferably 0.01 to 2.00 parts by weight, more preferably 0.10 to 1.00 parts by weight, and even more preferably 0.12 to 0.50 parts by weight, relative to 100 parts by weight of the conjugated diene-based polymer (A).

[0117] The total content of the two or more types of hindered phenol-based stabilizer (B) and aromatic amine-based stabilizer (C) in the stabilized conjugated diene-based polymer is not particularly limited, but is preferably 0.10 to 2.00 parts by weight, more preferably 0.20 to 1.20 parts by weight, per 100 parts by weight of the conjugated diene-based polymer (A).

[0118] The ratio of the content of the hindered phenol-based stabilizer (B) to the content of the aromatic amine-based stabilizer (C) in the stabilized conjugated diene polymer, expressed as a weight ratio of "hindered phenol-based stabilizer (B):aromatic amine-based stabilizer (C)", is preferably 10:1 to 0.1:1, more preferably 6:1 to 1:1, and even more preferably 4:1 to 2:1.

[0119] <Method for Producing Stabilized Conjugated Diene Polymer> The stabilized conjugated diene polymer of the present invention can be produced by adding a hindered phenol-based stabilizer (B) and an aromatic amine-based stabilizer (C) to a conjugated diene polymer (A).

[0120] The stabilized conjugated diene polymer of the present invention can be preferably produced by preparing a solution of the conjugated diene polymer (A) by a solution polymerization method, mixing the solution with the hindered phenol-based stabilizer (B) and the aromatic amine-based stabilizer (C), and then removing volatile components from the resulting mixed solution.

[0121] The conjugated diene polymer (A) used in the present invention can be obtained, for example, by polymerizing a monomer mixture containing at least a conjugated diene compound in an inert solvent using a polymerization initiator. The conjugated diene polymer (A) is preferably polymerized by a solution polymerization method.

[0122] Examples of the conjugated diene compound contained in the monomer mixture include the same compounds as those exemplified above as conjugated diene compounds that can be used to form the conjugated diene polymer (A). Furthermore, the monomer mixture may contain, as necessary, the above-mentioned aromatic vinyl monomer, a vinyl compound containing a functional group capable of interacting with silica, and other monomers.

[0123] The inert solvent used in the polymerization is one that is commonly used in solution polymerization, and is not particularly limited as long as it does not inhibit the polymerization reaction. Specific examples of the inert solvent include chain aliphatic hydrocarbons such as butane, pentane, hexane, heptane, and 2-butene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and cyclohexene; and aromatic hydrocarbons such as benzene, toluene, and xylene. These inert solvents may be used alone or in combination of two or more. The amount of the inert solvent used is an amount that results in a monomer concentration of, for example, 1 to 50% by weight, and preferably 10 to 40% by weight.

[0124] The polymerization initiator used in the polymerization is not particularly limited as long as it can polymerize a monomer mixture containing a conjugated diene compound. Specific examples include polymerization initiators using an organic alkali metal compound, an organic alkaline earth metal compound, or a lanthanum series metal compound as a main catalyst. Examples of organic alkali metal compounds include organic lithium compounds, organic sodium compounds, and organic potassium compounds. Specific examples include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenelithium; organic polyvalent lithium compounds such as dilithiomethane, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trillithiobenzene, and 1,3,5-tris(lithiomethyl)benzene; organic sodium compounds such as sodium naphthalene; and organic potassium compounds such as potassium naphthalene. Examples of organic alkaline earth metal compounds include di-n-butylmagnesium, di-n-hexylmagnesium, diethoxycalcium, calcium distearate, di-t-butoxystrontium, diethoxybarium, diisopropoxybarium, diethylmercaptobarium, di-t-butoxybarium, diphenoxybarium, diethylaminobarium, barium distearate, diketylbarium, etc. Examples of polymerization initiators using a lanthanum series metal compound as the main catalyst include polymerization initiators using a lanthanum series metal salt, such as lanthanum, cerium, praseodymium, neodymium, samarium, or gadolinium, as the main catalyst, which is composed of a lanthanum series metal salt formed from a carboxylic acid and a phosphorus-containing organic acid, etc., together with a co-catalyst such as an alkylaluminum compound, an organoaluminum hydride compound, or an organoaluminum halide compound. Among these polymerization initiators, organic monolithium compounds and organic polyvalent lithium compounds are preferably used, organic monolithium compounds are more preferably used, and n-butyllithium is particularly preferably used.The organic alkali metal compound may be used as an organic alkali metal amide compound by reacting it in advance with a secondary amine compound such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, piperidine, hexamethyleneimine, or heptamethyleneimine. By using the organic alkali metal amide compound as a polymerization initiator, the resulting cross-linked rubber product can be made to have better fuel economy and wear resistance. These polymerization initiators may be used alone or in combination of two or more.

[0125] The amount of the polymerization initiator used may be determined depending on the molecular weight distribution curve of the target conjugated diene polymer (A), and is usually in the range of 1 to 50 mmol, preferably 1.5 to 20 mmol, more preferably 2 to 15 mmol per 1000 g of monomer.

[0126] After initiating polymerization using a polymerization initiator, a polymerization initiator supplementation operation may be performed in which further polymerization initiator is added to the polymerization system to continue polymerization. The timing of the polymerization initiator supplementation operation and the number of times the polymerization initiator supplementation operation is performed are not particularly limited and may be determined depending on the molecular weight distribution curve of the desired conjugated diene polymer (A). The timing of the supplementation operation is preferably when the polymerization conversion rate reaches 10 to 90%, and more preferably when the polymerization conversion rate reaches 30 to 70%. From the viewpoint of excellent processability, a vinyl compound containing a functional group capable of interacting with silica is preferably copolymerized after the completion of the supplementation operation. The amount of polymerization initiator used per supplementation operation is not particularly limited and may be determined depending on the molecular weight distribution curve of the desired conjugated diene polymer (A). The amount is preferably 1 to 99 moles, more preferably 1.2 to 20 moles, per mole of polymerization initiator used at the start of polymerization.

[0127] The polymerization temperature is usually in the range of −80 to +150° C., preferably 0 to 100° C., and more preferably 30 to 90° C. As the polymerization mode, any mode such as a batch mode or a continuous mode can be adopted, but a batch mode is preferred in that it is easy to control the randomness of bonding between the conjugated diene monomer units and the aromatic vinyl monomer units.

[0128] Furthermore, when polymerizing a monomer mixture containing a conjugated diene compound, it is preferable to add a polar compound to the inert organic solvent in order to adjust the vinyl bond content in the conjugated diene monomer units in the resulting conjugated diene polymer (A). Examples of polar compounds include ether compounds such as dibutyl ether and tetrahydrofuran; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; and phosphine compounds. Among these, ether compounds and tertiary amines are preferred, with tetramethylethylenediamine, ethylene glycol diethyl ether, and ethylene glycol dibutyl ether being more preferred. These polar compounds may be used alone or in combination of two or more. The amount of polar compound used may be determined depending on the desired vinyl bond content, and is preferably 0.001 to 100 mol, more preferably 0.01 to 10 mol, per mol of polymerization initiator. When the amount of polar compound used is within this range, the vinyl bond content in the conjugated diene monomer units is easily adjusted and problems due to deactivation of the polymerization initiator are less likely to occur.

[0129] The conjugated diene polymer (A) used in the present invention may be obtained by a production method comprising the steps of: polymerizing an isoprene-containing monomer (a1) with a polymerization initiator in an inert solvent to form a polymer block (A1) having an active terminal; and mixing the polymer block (A1) having an active terminal with a 1,3-butadiene-containing monomer (a2) and continuing the polymerization reaction to form, in a continuous manner, a polymer block (A1) containing isoprene monomer units and a polymer block (A2) containing 1,3-butadiene monomer units. For example, the production method described in WO 2019 / 073828 can be used as such a production method.

[0130] By employing such a production method, the conjugated diene polymer (A) can be one containing a polymer block (A1) containing an isoprene monomer unit and a polymer block (A2) containing a 1,3-butadiene monomer unit, which are formed in a continuous manner.

[0131] The monomer (a1) for forming the polymer block (A1) may be any monomer containing isoprene, and a monomer corresponding to the monomer composition of the target polymer block (A1) may be used.

[0132] The polymer block (A1) is not particularly limited as long as it contains an isoprene monomer unit, and may be composed of only isoprene monomer units, or may be composed of isoprene monomer units and monomer units other than isoprene monomer units. In this case, the monomer units other than isoprene monomer units are preferably aromatic vinyl monomer units, and the polymer block (A1) preferably contains aromatic vinyl monomer units in addition to isoprene monomer units.

[0133] The polymer block (A2) is not particularly limited as long as it contains 1,3-butadiene monomer units, and may be composed of only 1,3-butadiene monomer units, or may be composed of 1,3-butadiene monomer units and monomer units other than 1,3-butadiene monomer units. In this case, a suitable example of the monomer units other than 1,3-butadiene monomer units is an aromatic vinyl monomer unit, and it is preferable that the polymer block (A2) contains aromatic vinyl monomer units in addition to 1,3-butadiene monomer units.

[0134] It is also preferable that at least one of the polymer block (A1) and the polymer block (A2) contains units of a vinyl compound containing a functional group capable of interacting with silica, and it is more preferable that at least the polymer block (A2) contains units of a vinyl compound containing a functional group capable of interacting with silica.

[0135] The polymer block (A2) is formed continuously with the polymer block (A1) by mixing the polymer block (A1) having the above-described active terminal with a monomer (a2) containing 1,3-butadiene and continuing the polymerization reaction. The formed polymer block (A2) has an active terminal. Meanwhile, the active terminal disappears from the polymer block (A1).

[0136] The weight ratio of the polymer block (A1) to the polymer block (A2) in the polymer chain having an active end (when a plurality of polymer blocks (A1) and polymer blocks (A2) are present, the weight ratio is based on the total weight of the respective polymer blocks) is (weight of polymer block (A1)) / (weight of polymer block (A2)), and is preferably from 0.001 to 0.2, more preferably from 0.005 to 0.1, and particularly preferably from 0.01 to 0.05.

[0137] In this manner, a conjugated diene polymer chain can be obtained in an inert solvent. The conjugated diene polymer chain thus obtained usually has an active terminal.

[0138] It is preferable to form a coupled polymer chain by reacting a conjugated diene polymer chain containing an active terminal with a coupling agent. Examples of the coupling agent include, but are not limited to, silicon tetrachloride, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, tin tetrachloride, methyltrichlorotin, dimethyldichlorotin, trimethylchlorotin, tetramethoxysilane, methyltrimethoxysilane, dimethoxydimethylsilane, methyltriethoxysilane, ethyltrimethoxysilane, dimethoxydiethylsilane, diethoxydimethylsilane, tetraethoxysilane, ethyltriethoxysilane, diethoxydiethylsilane, bis(trichlorosilyl)methane, 1,2-bis(trichlorosilyl)ethane, 1,3-bis(trichlorosilyl)propane, 1,4-bis(trichlorosilyl)butane, 1,5-bis(trichlorosilyl)pentane, and 1,6-bis(trichlorosilyl)hexane. The coupling agent may be selected depending on the molecular weight distribution curve of the target conjugated diene polymer (A). Preferably, a trifunctional or higher coupling agent is used, more preferably a tetrafunctional or higher coupling agent, and most preferably tin tetrachloride is used.

[0139] When a coupling agent is used, it is preferable to form coupled polymer chains by coupling reaction of a portion of the polymer chains having active ends obtained by the above polymerization method, thereby obtaining a solution containing the polymer chains having active ends and the coupled polymer chains. In this case, the amount of the coupling agent used is not particularly limited and may be selected depending on the molecular weight distribution curve of the target conjugated diene polymer (A). However, the amount is preferably 0.01 to 0.4 mol, more preferably 0.02 to 0.3 mol, calculated as functional groups of the coupling agent, per mol of the polymerization initiator used at the start of polymerization. By adding the coupling agent, the polymer chains having active ends undergo a coupling reaction at the active ends, and as a result, the active ends of the polymer chains that have undergone the coupling reaction disappear, becoming free of active ends, while the polymer chains that have not undergone the coupling reaction retain their active ends.

[0140] It is preferable to convert the conjugated diene polymer (A) into a conjugated diene polymer having a modifying group by reacting a modifying agent with an active terminal contained in the conjugated diene polymer chain obtained by polymerization or an active terminal that can be contained in the conjugated diene polymer chain after the coupling reaction. As the modifying agent, those described above as modifiers for forming the modifying group that can be contained in the conjugated diene polymer (A) used in the present invention can be used.

[0141] The amount of the modifier used when reacting the active terminal of the conjugated diene polymer chain with the modifier is not particularly limited, but the amount of the modifier per mole of the active terminal of the polymer chain having the active terminal (when an organic alkali metal compound is used as the polymerization initiator, the amount of the modifier per mole of metal atoms in the organic alkali metal compound) is preferably 0.01 to 10.0 moles, more preferably 0.02 to 5.0 moles, and particularly preferably 0.05 to 2.0 moles. The modifiers that can be used include those listed above, which may be used alone or in combination of two or more.

[0142] The method for reacting the active terminal of the conjugated diene polymer chain with the modifier is not particularly limited, but examples include a method in which the polymer chain having an active terminal and the modifier are mixed in a solvent capable of dissolving them. Examples of the solvent used in this process include those exemplified as the solvents used in the polymerization described above. In this process, it is preferable to leave the polymer chain having an active terminal obtained above in the state of the polymerization solution used in the polymerization and add the modifier to the solution, as this is simple and convenient. In this process, the modifier may be dissolved in the inert solvent used in the polymerization described above and added to the polymerization system, with the solution concentration preferably in the range of 1 to 50 wt %. The reaction temperature is not particularly limited, but is typically 0 to 120°C, and the reaction time is not particularly limited, but is typically 1 minute to 1 hour.

[0143] The timing of adding the modifier to the solution containing the polymer chains having active ends is not particularly limited, but it is desirable to add the modifier to the solution when the polymerization reaction is not complete and the solution containing the polymer chains having active ends also contains a monomer, more specifically, when the solution containing the polymer chains having active ends contains 100 ppm or more, more preferably 300 to 50,000 ppm of monomer. Adding the modifier in this manner makes it possible to suppress side reactions between the polymer chains having active ends and impurities contained in the polymerization system, and to effectively control the reaction.

[0144] It is preferable to add a polymerization terminator such as an alcohol such as methanol or isopropanol or water to the active terminals of the conjugated diene polymer chain obtained by polymerization, or to the active terminals that may remain after the reaction with a coupling agent or a modifying agent, as necessary, to deactivate the unreacted active terminals.

[0145] The conjugated diene polymer of the present invention can be produced by mixing the solution of the conjugated diene polymer (A) obtained by the above method with the hindered phenol-based stabilizer (B) and the aromatic amine-based stabilizer (C), and then removing the volatile components from the resulting mixed solution.

[0146] Examples of methods for removing volatile components from the mixed solution include steam stripping and heating the mixed solution under reduced pressure.

[0147] If desired, two or more conjugated diene polymers differing in monomer composition, molecular structure, molecular weight distribution curve, etc. may be mixed to obtain the conjugated diene polymer (A) used in the present invention. When mixing two or more conjugated diene polymers, the two or more conjugated diene polymers may be mixed in the form of polymer solutions or solids, but it is preferable to mix the two or more conjugated diene polymers in the form of solutions. That is, it is more preferable to prepare solutions of the two or more conjugated diene polymers to be mixed, respectively, and mix the prepared solutions.

[0148] <Rubber Composition> The rubber composition of the present invention contains the stabilized conjugated diene polymer of the present invention described above and a filler.

[0149] The rubber composition of the present invention may contain a polymer other than the conjugated diene polymer (A). Examples of other polymers include natural rubber (which may be modified natural rubber such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), highly purified natural rubber (UPNR), and grafted natural rubber), polyisoprene rubber, emulsion-polymerized styrene-butadiene copolymer rubber, solution-polymerized styrene-butadiene copolymer rubber, polybutadiene rubber (which may be high cis-BR or low cis-BR, or which may be polybutadiene rubber containing crystalline fibers made of 1,2-polybutadiene polymer), styrene-isoprene copolymer rubber, butadiene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylonitrile-styrene-butadiene copolymer rubber, butyl rubber (IIR), ethylene-propylene copolymer, chloroprene rubber, nitrile chloroprene rubber, and nitrile isoprene rubber, all of which are other than the conjugated diene polymer (A). Among these, natural rubber, polyisoprene rubber, polybutadiene rubber, and solution-polymerized styrene-butadiene copolymer rubber are preferred, with polybutadiene rubber being more preferred. These polymers can be used alone or in combination of two or more, such as natural rubber and polybutadiene rubber, or natural rubber and styrene-butadiene copolymer rubber.

[0150] In the rubber composition of the present invention, the conjugated diene polymer (A) in the stabilized conjugated diene polymer of the present invention preferably accounts for 10 to 100% by weight, particularly preferably 50 to 100% by weight, of the polymer components in the rubber composition.

[0151] Examples of fillers include silica, calcium silicate, aluminum silicate, carbon black, calcium carbonate, talc, aluminum hydroxide, alumina, clay, and mica. Among these, carbon black and silica are preferred, and silica is more preferred, from the viewpoint of further improving the low-temperature properties and bloom resistance of the resulting cross-linked rubber. These can be used alone or in combination of two or more. For example, carbon black and silica can be used in combination.

[0152] Examples of silica include dry process white carbon, wet process white carbon, colloidal silica, precipitated silica, calcium silicate, and aluminum silicate. Among these, wet process white carbon, which is mainly composed of hydrous silica, is preferred. Carbon-silica dual phase filler, in which silica is supported on the surface of carbon black, may also be used. These silicas may be used alone or in combination of two or more. The nitrogen adsorption specific surface area of ​​the silica used (measured by the BET method in accordance with ASTM D3037-81) is preferably 20 to 400 m ２ / g, more preferably 50 to 220 m ２ / g, particularly preferably 80 to 170 m ２ The pH of the silica is preferably 5 to 10.

[0153] As the silica, for example, various commercially available silicas can be used, such as "Hi-Sil 210," "Hi-Sil 233," and "Hi-Sil 243LD" manufactured by PPG Industries; "Zeosil 1115MP," "Zeosil 1165MP," and "Zeosil 165GR" manufactured by Solvay; "ULTRASIL VN2," "ULTRASIL VN3," "ULTRASIL 7000GR," and "ULTRASIL 9100GR" manufactured by EVONIK; and "NIPSIL VN3," "NIPSIL AQ," "NIPSIL ER," and "NIPSIL RS-150" manufactured by Tosoh Silica Corporation.

[0154] Examples of carbon black include furnace black, acetylene black, thermal black, channel black, and graphite. Examples of channel black include EPC, MPC, and CC. Examples of furnace carbon black include SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF. Examples of thermal black include FT and MT. Each carbon black can be used alone or in combination of two or more types.

[0155] The amount of filler blended in the rubber composition of the present invention is preferably 10 to 250 parts by weight, more preferably 15 to 150 parts by weight, and even more preferably 20 to 130 parts by weight, per 100 parts by weight of the polymer component in the rubber composition.

[0156] The rubber composition of the present invention may further contain a silane coupling agent from the viewpoint of further improving the properties of the resulting cross-linked rubber. The silane coupling agent is not particularly limited, and various silane coupling agents can be used, but in the present invention, sulfide-based, mercapto-based, protected mercapto-based (e.g., those having a carbonylthio group), thiocyanate-based, vinyl-based, amino-based, methacrylate-based, glycidoxy-based, nitro-based, epoxy-based, or chloro-based silane coupling agents can be suitably used. Specific examples of silane coupling agents include bis(3-(triethoxysilyl)propyl)disulfide, bis(3-(triethoxysilyl)propyl)trisulfide, bis(3-(triethoxysilyl)propyl)tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-[ ethoxybis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silyl]-1-propanethiol, 3-octanoylthio-1-propyl-triethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, γ-trimethoxysilylpropyl benzothiazyl tetrasulfide, 3-thiocyanatopropyl triethoxysilane, vinyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, 3-trimethoxysilylpropyl methacrylate monosulfide, γ-glycidoxypropyltriethoxysilane, 3-nitropropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-chloropropyltrimethoxysilane. Other silane coupling agents that can be used include NXT-Z100, NXT-Z30, NXT-Z45, NXT-Z60, and NXT manufactured by Momentive Performance Materials, and Si69, Si75, and VP Si363 manufactured by Evonik Degussa. These silane coupling agents can be used alone or in combination of two or more. One or more of these silane coupling agents may be oligomerized in advance and used in the oligomerized state.The amount of the silane coupling agent to be added is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight, per 100 parts by weight of the filler.

[0157] Furthermore, in addition to the above components, the rubber composition of the present invention may contain additives such as antioxidants, activators, process oils, plasticizers, lubricants, and tackifiers in required amounts, according to conventional methods.

[0158] To obtain the rubber composition of the present invention, the stabilized conjugated diene polymer of the present invention, the filler, and other components used as needed may be kneaded in a conventional manner. The kneading temperature is preferably 80 to 200°C, more preferably 120 to 180°C, and the kneading time is preferably 30 seconds to 30 minutes.

[0159] <Crosslinkable Rubber Composition> The crosslinkable rubber composition of the present invention contains the above-described rubber composition of the present invention and a crosslinking agent.

[0160] Examples of crosslinking agents include sulfur-containing compounds such as sulfur and sulfur halides, organic peroxides, quinone dioximes, organic polyamine compounds, and alkylphenol resins having methylol groups. Of these, sulfur is preferably used. The amount of crosslinking agent blended is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, per 100 parts by weight of the polymer components in the rubber composition.

[0161] Furthermore, in addition to the above components, the crosslinkable rubber composition of the present invention can be blended with required amounts of compounding agents such as crosslinking accelerators, crosslinking activators, antioxidants, activators, process oils, plasticizers, lubricants, and tackifiers according to conventional methods.

[0162] When sulfur or a sulfur-containing compound is used as the crosslinking agent, it is preferable to use a crosslinking accelerator and a crosslinking activator in combination. Examples of crosslinking accelerators include sulfenamide-based crosslinking accelerators; guanidine-based crosslinking accelerators; thiourea-based crosslinking accelerators; thiazole-based crosslinking accelerators; thiuram-based crosslinking accelerators; dithiocarbamic acid-based crosslinking accelerators; and xanthogenic acid-based crosslinking accelerators. Among these, those containing sulfenamide-based crosslinking accelerators are preferred. These crosslinking accelerators may be used alone or in combination of two or more. The amount of crosslinking accelerator blended is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, per 100 parts by weight of the polymer component in the crosslinkable rubber composition.

[0163] Examples of crosslinking activators include higher fatty acids such as stearic acid; zinc oxide; etc. These crosslinking activators are used either alone or in combination of two or more. The amount of crosslinking activator blended is preferably 0.05 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight, per 100 parts by weight of the polymer component in the crosslinkable rubber composition.

[0164] To obtain the crosslinkable rubber composition of the present invention, the components may be kneaded according to a conventional method. For example, the components excluding thermally unstable components such as crosslinking agents and crosslinking accelerators are kneaded with the stabilized conjugated diene polymer and filler, and then the thermally unstable components such as the crosslinking agent and crosslinking accelerator are mixed with the kneaded mixture to obtain the desired composition. The kneading temperature for the components excluding thermally unstable components, the stabilized conjugated diene polymer, and the filler is preferably 80 to 200°C, more preferably 120 to 180°C, and the kneading time is preferably 30 seconds to 30 minutes. The kneaded mixture is then mixed with the thermally unstable components after cooling to typically 100°C or below, preferably 80°C or below.

[0165] <Rubber Cross-Linked Product> The rubber cross-linked product of the present invention is obtained by cross-linking the above-described cross-linkable rubber composition of the present invention.

[0166] The cross-linked rubber product of the present invention can be produced by using the cross-linkable rubber composition of the present invention, for example, molding the composition into a desired shape using a molding machine such as an extruder, injection molding machine, compressor, or roll, and then heating to cause a cross-linking reaction and fix the shape as a cross-linked rubber product. In this case, cross-linking may be carried out after molding in advance or simultaneously with molding. The molding temperature is usually 10 to 200°C, preferably 25 to 120°C. The cross-linking temperature is usually 100 to 200°C, preferably 130 to 190°C, and the cross-linking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, and particularly preferably 3 minutes to 6 hours.

[0167] Depending on the shape, size, etc. of the cross-linked rubber, the surface may be cross-linked but the interior may not be sufficiently cross-linked, so secondary cross-linking may be carried out by further heating.

[0168] The heating method may be appropriately selected from common methods used for crosslinking rubber, such as press heating, steam heating, oven heating, and hot air heating.

[0169] The cross-linked rubber product of the present invention obtained in this manner is excellent in low heat buildup, wet grip performance, and handling stability. Therefore, by taking advantage of its excellent properties, the cross-linked rubber product of the present invention can be used in a variety of applications, such as materials for various tire parts such as cap tread, base tread, carcass, sidewalls, and bead portions in tires; materials for hoses, belts, mats, anti-vibration rubber, and various other industrial products; impact modifiers for resins; resin film cushioning agents; shoe soles; rubber shoes; golf balls; and toys. In particular, the cross-linked rubber product of the present invention is suitable as a tire material because of its excellent low heat buildup, wet grip performance, and handling stability.

[0170] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" are by weight unless otherwise specified. Tests and evaluations were carried out according to the following methods.

[0171] [Aromatic vinyl monomer unit content and vinyl bond content of conjugated diene polymer] The aromatic vinyl monomer unit content and vinyl bond content of the conjugated diene polymer are as follows: １ Measured by H-NMR.

[0172] [Mooney Viscosity (ML1+4, 100°C) of Stabilized Conjugated Diene Polymer] The Mooney viscosity (ML1+4) of the stabilized conjugated diene polymer was measured in accordance with JIS K6300-1:2013 under the following conditions: Test temperature: 100°C or 125°C Rotor type: L-type Testing machine used: Shimadzu Mooney Viscometer SMV-300J, manufactured by Shimadzu Corporation

[0173] [Mooney Viscosity Stability (1) of Stabilized Conjugated Diene Polymer] 100 parts by weight of stabilized conjugated diene polymer was preheated at 150°C for 3 minutes in a 60 cc Labo Plastomill and then masticated at 100 rpm for 70 seconds. After being discharged from the Labo Plastomill, the polymer was stored for 20 days in an atmosphere at 23°C and 50% humidity, and the Mooney viscosity (ML1+4, 100°C) after storage was measured. The change in Mooney viscosity (ML1+4, 100°C) due to storage was calculated by subtracting the Mooney viscosity (ML1+4, 100°C) after storage from the Mooney viscosity (ML1+4, 100°C) before storage. The calculated change is shown in Table 1 as the test result of Mooney viscosity stability (1) of stabilized conjugated diene polymer. Note that the closer the change is to 0, the more excellent the Mooney viscosity stability of the stabilized conjugated diene polymer during long-term storage.

[0174] [Mooney Viscosity Stability (2) of Stabilized Conjugated Diene Polymer] The stabilized conjugated diene polymer was stored in a constant temperature bath at 50°C for 14 days, and the Mooney viscosity (ML1+4, 100°C) after storage was measured. The change in Mooney viscosity (ML1+4, 100°C) due to storage was determined by subtracting the Mooney viscosity (ML1+4, 100°C) after storage from the Mooney viscosity (ML1+4, 100°C) before storage. The determined change is shown in Table 1 as the test result of Mooney viscosity stability (2) of the stabilized conjugated diene polymer. Note that the closer the change is to 0, the more excellent the Mooney viscosity stability of the stabilized conjugated diene polymer during long-term storage.

[0175] [Evaluation of Thermal Stability] 40 g of stabilized conjugated diene polymer was preheated at 150°C for 3 minutes in a 60 cc Labo Plastomill and then masticated at 100 rpm. The torque value during mastication was checked. If the torque value started to decrease once and then further increased by 2 points or more within 30 minutes of the start of mastication, the evaluation was given as "B", and if the torque value started to decrease once and then further increased by less than 2 points, the evaluation was given as "A". An evaluation of "A" indicates that the stabilized conjugated diene polymer has excellent thermal stability.

[0176] (Polymerization Example 1 [Polymerization Solution a1 of Conjugated Diene Polymer A1]) The atmosphere in a 20 L stainless steel polymerization reactor equipped with a stirrer was purged with dry nitrogen. Next, 10.2 kg of industrial hexane (manufactured by Sumitomo Chemical Co., Ltd., trade name: Hexane (general product), density 0.68 g / mL), 712 g of 1,3-butadiene, 388 g of styrene, 99 mmol of tetrahydrofuran, and 24.15 mmol of ethylene glycol diethyl ether were charged into the polymerization reactor. Next, an n-hexane solution containing n-butyllithium (n-BuLi) in an amount necessary to neutralize impurities contained in the system that inhibit polymerization was added to the polymerization reactor, and further, an n-hexane solution containing 16.06 mmol of n-butyllithium (n-BuLi) was charged into the polymerization reactor, and the mixture was stirred at a stirring speed of 160 rpm and an internal temperature of the polymerization reactor of 31°C. Immediately after the start of polymerization, 764 g of 1,3-butadiene and 168 g of styrene were continuously fed to the mixture over 90 minutes, and 15 minutes after the start of polymerization, 9.20 mmol of bis(diethylamino)methylvinylsilane was fed and the mixture was stirred. 90 minutes after the start of polymerization, 168 g of 1,3-butadiene was continuously fed to the mixture over 20 minutes while stirring the mixture, and further stirring was continued for 10 minutes to obtain a polymerization solution. Next, 1.24 mmol of tin tetrachloride was added to the obtained polymerization solution and stirred for 15 minutes, after which 11.1 mmol of N-(3-dimethylaminopropyl)acrylamide was added and the mixture was allowed to react for 10 minutes. Thereafter, methanol was added as a polymerization terminator in an amount equivalent to twice the molar amount of n-butyllithium used to obtain a polymerization solution a1 containing a conjugated diene-based polymer A1.

[0177] 10 g of the obtained polymerization solution a1 was sampled and dried under reduced pressure at 55° C. for 12 hours to obtain a conjugated diene polymer A1. When the obtained conjugated diene polymer A1 was measured according to the above-mentioned method, the styrene unit content was 25.9 wt % and the vinyl bond content in the butadiene units was 59.2 mol %.

[0178] In the following examples and comparative examples, the following stabilizers B1, B2, and C1 were used: Stabilizer B1: 2,4-bis[(octylthio)methyl]-o-cresol Stabilizer B2: octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamate Stabilizer C1: reaction product of N-phenylbenzenamine and 2,4,4-trimethylpentene

[0179] Example 1 [Stabilized Conjugated Diene Polymer P1] To a polymerization solution a1 containing 100 parts by weight of the conjugated diene polymer A1 obtained in Polymerization Example 1, 0.15 parts by weight of Stabilizer B1, 0.30 parts by weight of Stabilizer B2, and 0.15 parts by weight of Stabilizer C1 were added and stirred. Most of the volatile matter in the resulting polymerization solution was evaporated at room temperature for 24 hours, and the resulting solution was further dried under reduced pressure at 55°C for 12 hours to obtain a stabilized conjugated diene polymer P1. The thermal stability, Mooney viscosity stability (1), and Mooney viscosity stability (2) of the resulting stabilized conjugated diene polymer P1 were measured. The results are shown in Table 1.

[0180] Using the obtained stabilized conjugated diene polymer P1, a cross-linked rubber product was obtained in the same manner as in Example 1 of WO 2019 / 073829, and evaluation was carried out in the same manner as in Example 1 of WO 2019 / 073829. The cross-linked rubber product obtained was found to be excellent in low heat buildup, wet grip performance, and handling stability.

[0181] Comparative Example 1 [Stabilized Conjugated Diene Polymer P2] A stabilized conjugated diene polymer P2 was obtained in the same manner as in Example 1, except that 0.60 parts by weight of stabilizer B1 was added to polymerization solution a1 containing 100 parts by weight of conjugated diene polymer A1 obtained in Polymerization Example 1 and stirred. The thermal stability, Mooney viscosity stability (1) and Mooney viscosity stability (2) of the obtained stabilized conjugated diene polymer P2 were measured. The results are shown in Table 1.

[0182] Comparative Example 2 [Stabilized Conjugated Diene Polymer P3] A stabilized conjugated diene polymer P3 was obtained in the same manner as in Example 1, except that 0.20 parts by weight of Stabilizer B1 and 0.40 parts by weight of Stabilizer B2 were added to polymerization solution a1 containing 100 parts by weight of conjugated diene polymer A1 obtained in Polymerization Example 1 and stirred. The thermal stability, Mooney viscosity stability (1) and Mooney viscosity stability (2) of the obtained stabilized conjugated diene polymer P3 were measured. The results are shown in Table 1.

[0183] Comparative Example 3 [Stabilized Conjugated Diene Polymer P4] A stabilized conjugated diene polymer P4 was obtained in the same manner as in Example 1, except that 0.30 parts by weight of stabilizer B1 and 0.30 parts by weight of stabilizer C1 were added to polymerization solution a1 containing 100 parts by weight of conjugated diene polymer A1 obtained in Polymerization Example 1 and stirred. The thermal stability, Mooney viscosity stability (1) and Mooney viscosity stability (2) of the obtained stabilized conjugated diene polymer P4 were measured. The results are shown in Table 1.

[0184]

[0185] As shown in Table 1, a stabilized conjugated diene polymer obtained by adding two or more types of hindered phenol stabilizer (B) and aromatic amine stabilizer (C) to a conjugated diene polymer (A) containing a tin atom and / or a silicon atom had excellent Mooney viscosity stability during storage (Example 1).

Claims

1. A stabilized conjugated diene polymer comprising a conjugated diene polymer containing a tin atom and / or a silicon atom, two or more hindered phenol stabilizers, and an aromatic amine stabilizer.

2. The stabilized conjugated diene polymer according to claim 1, wherein the conjugated diene polymer contains a tin atom.

3. The stabilized conjugated diene polymer according to claim 1 or 2, wherein the conjugated diene polymer comprises a functional group capable of interacting with silica.

4. The stabilized conjugated diene polymer according to claim 1 or 2, wherein the conjugated diene polymer comprises units of a vinyl compound containing a functional group capable of interacting with silica.

5. The stabilized conjugated diene polymer according to claim 4, wherein the unit of the vinyl compound containing a functional group capable of interacting with the silica is a unit represented by the following general formula (3). 【Chemistry 10】 (In the above general formula (3), X ５ X represents a chemical single bond or a hydrocarbylene group. ６ , X ７ and X ８ Each of these independently represents a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have substituents.

6. The stabilized conjugated diene polymer according to claim 1 or 2, wherein the total content of the hindered phenol stabilizer relative to 100 parts by weight of the conjugated diene polymer is 0.01 to 2.00 parts by weight.

7. The stabilized conjugated diene polymer according to claim 1 or 2, wherein the content of the aromatic amine stabilizer per 100 parts by weight of the conjugated diene polymer is 0.01 to 2.00 parts by weight.

8. The stabilized conjugated diene polymer according to claim 1 or 2, comprising, as the hindered phenol stabilizer, a hindered phenol stabilizer containing a sulfur atom and a hindered phenol stabilizer not containing a sulfur atom.

9. The stabilized conjugated diene polymer according to claim 1 or 2, comprising a semi-hindered phenol stabilizer and a double-hindered phenol stabilizer as the aforementioned hindered phenol stabilizer.

10. The stabilized conjugated diene polymer according to claim 1 or 2, wherein the ratio of the content of the hindered phenol-based stabilizer to the content of the aromatic amine-based stabilizer is 10:1 to 0.1:1 in weight ratio expressed as "hindered phenol-based stabilizer: aromatic amine-based stabilizer".

11. A rubber composition comprising a stabilized conjugated diene polymer according to claim 1 or 2 and a filler.

12. A crosslinkable rubber composition containing the rubber composition described in claim 11 and a crosslinking agent.

13. A crosslinked rubber product obtained by crosslinking the crosslinkable rubber composition described in claim 12.

14. A tire comprising the rubber crosslinking material described in claim 13.

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