Conjugated diene polymer, rubber composition, cross-linked rubber, and tire

Abstract

Provided is a conjugated diene-based polymer containing at least a conjugated diene monomer unit, wherein the content of silicone is at least 95 wt ppm, and the ionic strength index is at most 75%.

Description

[Technical Field]

[0001] The present invention relates to a conjugated diene polymer, a rubber composition, a cross-linked rubber product, and a tire, and more particularly to a conjugated diene polymer that has excellent processability and can give a cross-linked rubber product that is excellent in abrasion resistance and fuel economy, and a rubber composition, a cross-linked rubber product, and a tire obtained by using such a conjugated diene polymer. [Background technology]

[0002] In recent years, with the growing interest in environmental issues, polymers used in automobile tires are also 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] As a conjugated diene polymer used to provide such a tire, Patent Document 1 discloses a conjugated diene polymer that satisfies the following (1) to (4): (1) The molecular weight distribution curve obtained by gel permeation chromatography (GPC) measurement has two or more peaks. (2) The molecular weight distribution curve contains a peak (A) having a peak molecular weight of 500,000 to 2,500,000 and a peak (B) having a peak molecular weight of 150,000 to 600,000. (3) The sum of the area of ​​the peak (A) and the area of ​​the peak (B) is 70% or more of the entire molecular weight distribution curve. (4) The absolute value of the difference between the glass transition temperature (Tg(A)) of the conjugated diene polymer contained in the peak (A) and the glass transition temperature (Tg(B)) of the conjugated diene polymer contained in the peak (B) is 2°C to 30°C. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 147312 Summary of the Invention [Problem to be solved by the invention]

[0005] The conjugated diene polymer obtained by the technique of Patent Document 1 above does not have sufficient processability, and the cross-linked rubber obtained using the same leaves room for improvement in wear resistance and fuel economy.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a conjugated diene polymer that has excellent processability and can give a cross-linked rubber product that is excellent in abrasion resistance and fuel economy. Another object of the present invention is to provide a rubber composition, a cross-linked rubber product, and a tire obtained using such a conjugated diene polymer. [Means for solving the problem]

[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 setting the silicon content and ionic strength index of a conjugated diene polymer within specific ranges, and have thus completed the present invention.

[0008] That is, according to the present invention, there is provided a conjugated diene polymer containing at least a conjugated diene monomer unit, which has a silicon content of 95 ppm by weight or more and an ionic strength index of 75% or less.

[0009] In the conjugated diene polymer of the present invention, the molecular weight distribution (Mw / Mn) is preferably 1.5 or more. The conjugated diene polymer of the present invention preferably has a weight average molecular weight (Mw) of 200,000 or more, and the conjugated diene polymer of the present invention preferably has a silicon content of 150 ppm by weight or more. The conjugated diene polymer of the present invention preferably has an ionic strength index of 0.5 to 60%. In the conjugated diene polymer of the present invention, the number of peaks in the molecular weight distribution curve is preferably 2 or more. The conjugated diene polymer of the present invention preferably contains a terminal modified group.

[0010] According to the present invention, there is provided a rubber composition containing the above conjugated diene polymer and a filler. Furthermore, according to the present invention, there are provided a cross-linked rubber product obtained by cross-linking the above rubber composition, and a tire including such a cross-linked rubber product. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a conjugated diene polymer that has excellent processability and can give a cross-linked rubber product that is excellent in wear resistance and fuel economy. Furthermore, according to the present invention, it is also possible to provide a rubber composition, a cross-linked rubber product, and a tire obtained using such a conjugated diene polymer. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Conjugated diene polymer> The conjugated diene polymer of the present invention is a conjugated diene polymer containing at least a conjugated diene monomer unit, and has a silicon content of 95 ppm by weight or more and an ionic strength index of 75% or less.

[0013] The conjugated diene polymer of the present invention contains conjugated diene monomer units, and examples of conjugated diene monomers 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. 1,3-butadiene and isoprene may also be used in combination.

[0014] The lower limit of the content of the conjugated diene monomer units in the conjugated diene polymer of the present invention may be 0% by weight or more, but from the viewpoint of the abrasion resistance and fuel economy of the resulting cross-linked rubber product, the total amount of all monomers is taken as 100% by weight, and the lower limit is preferably 20% by weight or more, more preferably 25% by weight or more, even more preferably 30% by weight or more, particularly preferably 40% by weight or more, and most preferably 50% by weight or more. On the other hand, the upper limit of the content of the conjugated diene monomer units may be 100% by weight or less, but from the viewpoint of the processability of the conjugated diene polymer, the preferred upper limits are, in order of preference, 95% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 66% by weight or less, 64% by weight or less, 62% by weight or less, and 60% by weight or less, based on the total amount of all monomers taken as 100% by weight.

[0015] In the conjugated diene polymer of the present invention, the vinyl bond content in the conjugated diene monomer units is preferably 1 to 90 mol%, more preferably 3 to 80 mol%, even more preferably 5 to 70 mol%, still more preferably 7 to 60 mol%, particularly preferably 9 to 50 mol%, and most preferably 10 to 40 mol%. By setting the vinyl bond content in the conjugated diene monomer units within the above range, the fuel economy properties of the obtained cross-linked rubber can be further improved.

[0016] Furthermore, the conjugated diene polymer of 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. The upper limit of the aromatic vinyl monomer unit content in the conjugated diene polymer may be 0% by weight or more. However, from the viewpoint of the abrasion resistance and fuel economy of the resulting cross-linked rubber, the upper limit is preferably 80% by weight or less, more preferably 75% by weight or less, even more preferably 70% by weight or less, particularly preferably 60% by weight or less, and most preferably 50% by weight or less, based on the total amount of all monomers as 100% by weight. On the other hand, the lower limit of the content of the aromatic vinyl monomer unit may be 0% by weight or more. However, from the viewpoint of the processability of the conjugated diene polymer, the preferred lower limit is, in order of preference, 5% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, 25% by weight or more, 30% by weight or more, 34% by weight or more, 36% by weight or more, 38% by weight or more, and 40% by weight or more, where the total amount of all monomers is 100% by weight.

[0017] When the conjugated diene polymer of the present invention contains an aromatic vinyl monomer unit, the aromatic vinyl monomer block ratio in the conjugated diene polymer of the present invention is preferably 30.0% or less, more preferably 20.0% or less, even more preferably 10.0% or less, and particularly preferably 5.0% or less. The aromatic vinyl monomer block ratio is measured by 1H-NMR using deuterated chloroform as a solvent. The peaks at 6.1 to 7.7 ppm in the obtained 1H-NMR spectrum are considered to be those attributable to the aromatic vinyl monomer, and of these, the peaks at 6.1 to 6.88 ppm are considered to be those attributable to the aromatic vinyl monomer block. The ratio of the peak area attributable to the aromatic vinyl monomer block to the peak area attributable to the aromatic vinyl monomer is calculated, and this value is multiplied by 2.5 to express it as a percentage to determine the aromatic vinyl monomer block ratio. When the aromatic vinyl monomer is styrene, the styrene block ratio is preferably within the above range. By controlling the aromatic vinyl monomer block ratio within the above range, the resulting cross-linked rubber product can have a better balance of wear resistance and fuel economy.

[0018] The aromatic vinyl monomer block ratio can be controlled by adjusting the timing of adding the conjugated diene monomer and the aromatic vinyl monomer to the polymerization system. The conjugated diene monomer and the aromatic vinyl monomer can be added to the polymerization system at any timing, regardless of whether they are added before or after the addition of the polymerization initiator.

[0019] Furthermore, the conjugated diene-based polymer of 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.

[0020] The vinyl compound that contains functional groups that can interact with silica and that can form the unit of the vinyl compound that contains functional groups that can interact with silica can be any compound that contains a functional group that can interact with silica and a vinyl group, and is not particularly limited.Here, the functional group that can interact with silica is the functional group that can form a covalent bond between this functional group and the silica surface, or can form intermolecular forces that are weaker than covalent bonds (for example, ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.).The functional group that can interact with silica is not particularly limited, but can include nitrogen atom-containing functional groups, silicon atom-containing functional groups, oxygen atom-containing functional groups, etc.Among these, silicon atom-containing functional groups are preferred because of their high interaction with silica.

[0021] 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 can be suitably used, for example, a compound represented by the following general formula (1): [ka] 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.

[0022] In the above general formula (1), X 1 is a chemical single bond or a hydrocarbylene group, preferably a chemical single bond. Examples of the hydrocarbylene group include an alkylene group, an alkenediyl group, an arylene group, and a group in which an arylene group and an alkylene group are bonded together. Examples of alkylene groups include methylene, ethylene, and trimethylene groups. Examples of alkenediyl groups include vinylene and ethylene-1,1-diyl groups. Examples of arylene groups include phenylene, naphthylene, 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.

[0023] In the above general formula (1), X 2 , X 3 and X 4 X 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.

[0024] 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. R 1 -N(-R 2 )- (2) In the above general formula (2), R 1 and R 2 may or may not be bonded to each other, and R 1 and R 2 If they are not bonded to each other, R 1 and R 2 each independently represents a hydrocarbyl group or a trihydrocarbylsilyl group which may have a substituent, and R 1 and R 2When and are bonded to each other, 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.

[0025] R 1 and R 2 Examples of hydrocarbyl groups that can constitute the above 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. R 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 a substituent, and examples of the hydrocarbyl group having a hydrocarbyloxy group as a substituent include alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and a methoxyethyl group; and aryloxyalkyl groups such as a phenoxymethyl group.

[0026] 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.

[0027] R 1 and R 2 When and are bonded to each other, R 1 and R 2Examples of the hydrocarbylene group that can constitute R include alkylene groups such as trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, decamethylene, dodecamethylene, and 2,2,4-trimethylhexane-1,6-diyl; and alkenediyl groups such as pentan-2-ene-1,5-diyl. 1 and R 2 When the hydrocarbylene group that can constitute the formula (I) contains at least one selected from a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom, examples of the hydrocarbylene group containing at least one selected from a nitrogen atom, an oxygen atom, a sulfur atom, and a silicon atom include a group represented by -CH=N-CH=CH-, a group represented by -CH=N-CH2-CH2-, a group represented by -CH2-CH2-O-CH2-CH2-, a group represented by -CH2-CH2-S-CH2-CH2-, a group represented by -CH2-CH2-SiH2-CH2-CH2-, a group represented by -CH2-CH2-SiMe2-CH2-CH2-, and a group represented by -CH2-CH2-SiEt2-CH2-CH2-. 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 1 and R 2 is more preferably a methyl group or an ethyl group.

[0028] In the above general formula (2), R 1 and R 2When is a hydrocarbyl group, specific examples of the group represented by the above general formula (2) 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.

[0029] In the above general formula (2), R 1 and R 2 When the group represented by the general formula (2) is a hydrocarbyl group having a hydrocarbyloxy group as a substituent, specific examples of the group represented by the general formula (2) include di(alkoxyalkyl)amino groups such as di(methoxymethyl)amino and di(ethoxymethyl)amino.

[0030] In the above general formula (2), R 1 and R 2 When 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.

[0031] In the above general formula (2), R 1 and R 2 and (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.

[0032] In the above general formula (2), R 1 and R 2and 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.

[0033] 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.

[0034] 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.

[0035] In the above general formula (1), X 2 , X 3 and X 4 Examples of hydrocarbyl groups that can constitute the above formula 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. X 2 , X 3 and X 4 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 thereof include alkoxyalkyl groups such as a methoxymethyl group, an ethoxymethyl group, and an ethoxyethyl group.

[0036] 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), when 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; and the like.

[0037] 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), when 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.

[0038] 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 silicon atom-containing functional groups represented by the above general formula (1) in the case where two of them 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[bis(trialkylsilyl)amino]alkylvinylsilanes; 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.

[0039] 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.

[0040] 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) when 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.

[0041] 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 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.

[0042] 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 a silicon atom-containing functional group represented by the above general formula (1), when none of the functional groups is a substituted amino group, include trialkoxyvinylsilanes such as trimethoxyvinylsilane, triethoxyvinylsilane, and tripropoxyvinylsilane; dialkoxyalkylvinylsilanes such as methyldimethoxyvinylsilane and methyldiethoxyvinylsilane; dialkoxyarylvinylsilanes such as di(tert-pentoxy)phenylvinylsilane and di(tert-butoxy)phenylvinylsilane; monoalkoxydialkylvinylsilanes such as dimethylmethoxyvinylsilane; monoalkoxydiarylvinylsilanes such as tert-butoxydiphenylvinylsilane and tert-pentoxydiphenylvinylsilane; monoalkoxyalkylarylvinylsilanes such as tert-butoxymethylphenylvinylsilane and tert-butoxyethylphenylvinylsilane; and substituted alkoxyvinylsilane compounds such as tris(β-methoxyethoxy)vinylsilane.

[0043] Among the compounds represented by the general formula (1), X 1 is preferably a chemical single bond, and X1 is 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, and X 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.

[0044] 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.

[0045] 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.

[0046] When the compound represented by the above 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 of the present invention as a unit of the vinyl compound containing a functional group capable of interacting with silica. [ka] In the above general formula (3), X 5 represents a chemical single bond or a hydrocarbylene group, and X 6 , X 7 and X8 each independently represents a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0047] 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.

[0048] In the conjugated diene polymer of the present invention, the content of vinyl compound units containing a functional group capable of interacting with silica is preferably 0 to 10,000% by weight, more preferably 0.001 to 3,000% by weight, and even more preferably 0.002 to 1,000% by weight, based on the total amount of all monomer units being 100% by weight. By setting the content of vinyl compound units containing a functional group capable of interacting with silica within the above range, the processability of the conjugated diene polymer and the abrasion resistance and fuel economy of the resulting cross-linked rubber can be further improved in a well-balanced manner.

[0049] The conjugated diene polymer of the present invention may also contain other monomer units in addition to the conjugated diene monomer units, the aromatic vinyl monomer units optionally contained, and the vinyl compound units containing functional groups capable of interacting with silica. Examples of other compounds constituting such other monomer units include linear olefin compounds such as ethylene, propylene, and 1-butene; cyclic olefin compounds such as cyclopentene and 2-norbornene; and non-conjugated diene compounds such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene.

[0050] The bonding pattern of each monomer unit in the conjugated diene polymer of the present invention can 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 obtained cross-linked rubber can be further improved.

[0051] Furthermore, the conjugated diene polymer of the present invention preferably contains a modifying group, and more preferably contains a modifying group (terminal modified group) obtained by modifying the end of the polymer chain of the conjugated diene polymer with a modifying agent. In this specification, the "conjugated diene polymer containing a modifying group" may be one in which at least a part of the polymer chain constituting the conjugated diene polymer contains a modifying group, that is, a part of the polymer chain constituting the conjugated diene polymer may not contain a modifying group.

[0052] 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 further improving the 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 (e.g., ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.). The interaction formed between silica and the functional group is preferably a covalent bond or an intermolecular force weaker than a covalent bond (e.g., ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.), and more preferably a weak intermolecular force (e.g., ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.) from the viewpoint of easily controlling the ionic strength index within a suitable range. The functional group capable of interacting with silica is not particularly limited, but examples thereof include a nitrogen atom-containing functional group, a silicon atom-containing functional group, and an oxygen atom-containing functional group.

[0053] As the modifier for forming the modifying group, from the viewpoint of high interaction with silica, silicon atom-containing modifiers having a silicon atom-containing functional group and nitrogen atom-containing modifiers having a nitrogen atom-containing functional group are preferred, and silicon atom-containing modifiers are more preferred. Examples of silicon atom-containing modifiers include siloxane compounds and hydrocarbyloxysilane compounds. Examples of nitrogen atom-containing modifiers include N,N-disubstituted aminoalkyl(meth)acrylamides such as dimethylaminoethylacrylamide, diethylaminoethylacrylamide, dimethylaminopropylacrylamide, diethylaminopropylacrylamide, dimethylaminobutylacrylamide, diethylaminobutylacrylamide, dimethylaminoethylmethacrylamide, diethylaminoethylmethacrylamide, dimethylaminopropylmethacrylamide, diethylaminopropylmethacrylamide, dimethylaminobutylmethacrylamide, and diethylaminobutylmethacrylamide. 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.

[0054] The siloxane compound is not particularly limited as long as it has a siloxane structure (—Si—O—) as the main chain structure, but organosiloxanes having organic groups on the side chains are preferred, and polyorganosiloxanes represented by the following general formula (4) are more preferred. [ka]

[0055] In the above general formula (4), R 3 ~R10 is 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. X 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. X 10 is 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 multiple X's, they may be the same or different. 11 is a group containing 2 to 20 repeating units of alkylene glycol, 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.

[0056] 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.

[0057] In addition, in the polyorganosiloxane represented by the general formula (4), X 9 , X 10 and X 12Examples 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.

[0058] 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 include groups represented by the following general formula (5). -Z 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.

[0059] 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.

[0060] 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 12is 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.

[0061] 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). [ka] 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 13 is an alkylene group having 3 carbon atoms, and R 11 is a hydrogen atom and X 14 is preferably a methoxy group.

[0062] 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 becomes easier to produce, and its viscosity does not become too high, making it easier to handle.

[0063] 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 proceeds easily in the production process of the conjugated diene polymer. 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.

[0064] The hydrocarbyloxysilane compound is a silicon-containing compound having at least one hydrocarbyloxy group.The hydrocarbyloxysilane compound is preferably a compound having at least one nitrogen atom-containing group in addition to the hydrocarbyloxy group, and more preferably, the nitrogen atom-containing group has a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom.

[0065] Such a hydrocarbyloxysilane compound is not particularly limited, but a compound represented by the following general formula (7) can be suitably used. [ka] In the above general formula (7), R 12 is a hydrocarbyl group, and 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.

[0066] R in the above general formula (7) 12is a hydrocarbyl group, and examples thereof include alkyl groups, cycloalkyl groups, alkenyl groups, aryl groups, and aralkyl groups, with an alkyl group having 1 to 6 carbon atoms being preferred. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, ethyl group, n-propyl group, isopropyl group, butyl group, pentyl group, and hexyl group, with a methyl group and an ethyl group being more preferred.

[0067] A in the above general formula (7) 1 is a hydrocarbyloxy group, and examples thereof include alkoxy groups such as a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group; alkenyloxy groups such as a vinyloxy group and an allyloxy group; aryloxy groups such as a phenoxy group and a naphthoxy group; and aralkyloxy groups such as a benzyloxy group. Among these, from the viewpoint of reactivity, alkoxy groups and aryloxy groups are preferred, alkoxy groups are more preferred, and methoxy and ethoxy groups are particularly preferred.

[0068] A in the above general formula (7) 2is a group containing a nitrogen atom, and is not particularly limited as long as it is a group containing a nitrogen atom, but is preferably an organic group having a nitrogen atom, and examples thereof include a 3-aminopropyl group, a 4-aminobutyl group, a 3-(2-aminoethylamino)propyl group, a 2-dimethylaminoethyl group, a 3-dimethylaminopropyl group, a 3-diethylaminopropyl group, a 3-dipropylaminopropyl group, a 3-dibutylaminopropyl group, a 3-phenylmethylaminopropyl group, a 3-(4-methylpiperazinyl)propyl group, an N,N-bis(trimethylsilyl)aminopropyl group, an N,N-bis(triethylsilyl)aminopropyl group, and an N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyl group. Among these, from the viewpoint of further improving the low heat buildup and wet grip properties of the obtained cross-linked rubber, groups containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom, such as a 3-aminopropyl group, a 4-aminobutyl group, or a 3-(2-aminoethylamino)propyl group, are preferred. Note that an "active hydrogen atom" refers to a hydrogen atom bonded to an atom other than a carbon atom, and preferably has a bond energy lower than that of the carbon-hydrogen bond in a polymethylene chain.

[0069] In the compound represented by the general formula (7), p is an integer of 0 to 2, q is an integer of 1 to 3, and r is an integer of 1 to 3, with p+q+r=4. From the viewpoint of reactivity with the polymer chain having an active terminal and the reaction residue generated by the reaction of the polymer chain having an active terminal with the siloxane compound, p is preferably an integer of 0 to 1, q is an integer of 2 to 3, and r is an integer of 1 to 2, and more preferably p=0, q=3, and r=1. When p is 2, two R groups are contained in one molecule of the compound represented by the general formula (7), 12 Similarly, when q is 2 or 3, a plurality of A groups contained in one molecule of the compound represented by general formula (7) may be the same or different from each other. 1The groups represented by may be the same or different from each other, and when r is 2 or 3, a plurality of A 2 The groups represented by the formula (I) may be the same or different from each other.

[0070] Specific examples of the compound represented by the general formula (7) are not particularly limited, but include, for example, A 2 is a group containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom, such as 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropylmethyldiethoxysilane, and 3-aminopropyltriethoxysilane. 2 compounds having a 3-aminopropyl group; A such as 4-aminobutyldimethylmethoxysilane, 4-aminobutylmethyldimethoxysilane, 4-aminobutyltrimethoxysilane, 4-aminobutyldimethylethoxysilane, 4-aminobutylmethyldiethoxysilane, and 4-aminobutyltriethoxysilane; 2 compounds having a 4-aminobutyl group; 3-(2-aminoethylamino)propyldimethylmethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyldimethylethoxysilane, 3-(2-aminoethylamino)propylmethyldiethoxysilane, 3-(2-aminoethylamino)propyltriethoxysilane, etc. 2 Examples of the 3-(2-aminoethylamino)propyl group include compounds having a 3-(2-aminoethylamino)propyl group. 2 As the silane, a compound having a 3-(2-aminoethylamino)propyl group is preferred, and 3-(2-aminoethylamino)propyltrimethoxysilane is more preferred.

[0071] In addition, A in general formula (7) 2is a group other than a group containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom, such as 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-dimethylaminopropyldimethylmethoxysilane, 3-dimethylaminopropyltriethoxysilane, 3-dimethylaminopropylmethyldiethoxysilane, and 3-dimethylaminopropyldimethylethoxysilane. 2 as the A, compounds having a 3-dimethylaminopropyl group; [3-(diethylamino)propyl]trimethoxysilane, 3-diethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyldimethylmethoxysilane, 3-diethylaminopropyltriethoxysilane, 3-diethylaminopropylmethyldiethoxysilane, 3-diethylaminopropyldimethylethoxysilane, etc. 2 compounds having a 3-diethylaminopropyl group; 3-dipropylaminopropyltrimethoxysilane, 3-dipropylaminopropylmethyldimethoxysilane, 3-dipropylaminopropyldimethylmethoxysilane, 3-dipropylaminopropyltriethoxysilane, 3-dipropylaminopropylmethyldiethoxysilane, 3-dipropylaminopropyldimethylethoxysilane, etc. 2 as the A, compounds having a 3-dipropylaminopropyl group; 3-dibutylaminopropyltrimethoxysilane, 3-dibutylaminopropylmethyldimethoxysilane, 3-dibutylaminopropyldimethylmethoxysilane, 3-dibutylaminopropyltriethoxysilane, 3-dibutylaminopropylmethyldiethoxysilane, 3-dibutylaminopropyldimethylethoxysilane, etc. 2 Compounds having a 3-dibutylaminopropyl group; 3-phenylmethylaminopropyltrimethoxysilane, 3-phenylmethylaminopropylmethyldimethoxysilane, 3-phenylmethylaminopropyldimethylmethoxysilane, 3-phenylmethylaminopropyltriethoxysilane, 3-phenylmethylaminopropylmethyldiethoxysilane, 3-phenylmethylaminopropyldimethylethoxysilane, etc.2 as the methyl group, a compound having a 3-phenylmethylaminopropyl group; 3-(4-methylpiperazinyl)propyltrimethoxysilane, 3-(4-methylpiperazinyl)propylmethyldimethoxysilane, 3-(4-methylpiperazinyl)propyldimethylmethoxysilane, 3-(4-methylpiperazinyl)propyltriethoxysilane, 3-(4-methylpiperazinyl)propylmethyldiethoxysilane, 3-(4-methylpiperazinyl)propyldimethylethoxysilane, etc. 2 as a compound having a 3-(4-methylpiperazinyl)propyl group;

[0072] A such as N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, and N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane 2 compounds having an N,N-bis(trimethylsilyl)aminopropyl group; N,N-bis(triethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(triethylsilyl)aminopropylmethyldimethoxysilane, N,N-bis(triethylsilyl)aminopropylmethyldiethoxysilane, etc. 2 Examples of the A include compounds having an N,N-bis(triethylsilyl)aminopropyl group; N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane. 2 Examples of the compound A include compounds having an N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyl group.2 As the silane, a compound having a 3-dimethylaminopropyl group is preferred, and 3-dimethylaminopropyltrimethoxysilane is more preferred.

[0073] Furthermore, as the hydrocarbyloxysilane compound, a compound represented by the following general formula (8) can also be suitably used. [ka] In the above general formula (8), A 3 is a hydrocarbyloxy group, and R 13 represents a hydrocarbon group which may have a substituent, and R 14 and R 15 each independently represents a hydrocarbon group which may have a substituent, R 14 and R 15 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.

[0074] A in the above general formula (8) 3 is a hydrocarbyloxy group, and examples thereof include alkoxy groups such as a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group; alkenyloxy groups such as a vinyloxy group and an allyloxy group; aryloxy groups such as a phenoxy group and a naphthoxy group; and aralkyloxy groups such as a benzyloxy group. Among these, from the viewpoint of reactivity, alkoxy groups and aryloxy groups are preferred, alkoxy groups are more preferred, and methoxy and ethoxy groups are particularly preferred.

[0075] In the above general formula (8), s (i.e., A 3The number of groups represented by the formula (8) is an integer of 0 to 2, and s is preferably 2. When s is 2 in the general formula (8), two A groups are contained in one molecule of the compound represented by the general formula (8). 3 The groups represented by the formula (I) may be the same or different from each other.

[0076] In the above general formula (8), R 13 represents a hydrocarbon group which may have a substituent. 13 The hydrocarbon group that can be R is not particularly limited, but includes alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; alkenyl groups such as vinyl and allyl; alkynyl groups such as ethynyl and propynyl; aryl groups such as phenyl and naphthyl; and aralkyl groups such as benzyl. Among these, alkyl and aryl groups are preferred, alkyl groups are more preferred, and methyl and ethyl groups are particularly preferred. In addition, R 13 The hydrocarbon group represented by the formula (8) may have a substituent other than the hydrocarbon group, and the substituent is not particularly limited, but examples thereof include a carbonyl group-containing group such as a carboxyl group, an acid anhydride group, a hydrocarbylcarbonyl group, an alkoxycarbonyl group, and an acyloxy group, an epoxy group, an oxy group, a cyano group, an amino group, and a halogen group. When s in the formula (8) is 0, two R groups are contained in one molecule of the compound represented by the formula (8). 13 The groups represented by the formula (I) may be the same or different from each other.

[0077] In the above general formula (8), R 14 and R 15 each independently represents a hydrocarbon group which may have a substituent, R 14 and R 15may be bonded to each other to form a ring structure, and may form a ring structure together with the nitrogen atom to which they are bonded. In addition, when these form a ring structure, they may also 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. 14 and R 15 When they do not bond with each other, R 14 and R 15 The hydrocarbon group that can be R is not particularly limited, but includes alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; alkenyl groups such as vinyl and allyl; alkynyl groups such as ethynyl and propynyl; aryl groups such as phenyl and naphthyl; and aralkyl groups such as benzyl. Among these, alkyl and aryl groups are preferred, alkyl groups are more preferred, and methyl and ethyl groups are particularly preferred. In addition, R 14 and R 15 When they are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, R 14 and R 15 The divalent hydrocarbon group formed by bonding is not particularly limited, but examples thereof include alkylene groups such as an n-butylene group (when these form a 1-pyrrolidine group together with the nitrogen atom to which they are bonded in general formula (8)) and an n-pentylene group (when they form a 1-piperidine group), and a butadienylene group (when they form a 1-pyrrole group). In addition, R 14 and R 15 When they are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, the ring structure is preferably a 4- to 8-membered ring structure.

[0078] Also, R 14 and R 15The hydrocarbon group represented by the formula (I) may have a substituent other than the hydrocarbon group, regardless of whether a ring structure is formed or not, and the substituent is not particularly limited, but examples thereof include carbonyl group-containing groups such as a carboxyl group, an acid anhydride group, a hydrocarbylcarbonyl group, an alkoxycarbonyl group, and an acyloxy group, as well as an epoxy group, an oxy group, a cyano group, an amino group, and a halogen group. 14 and R 15 When they bond to each other to form a ring structure together with the nitrogen atom to which they are bonded, the atoms forming the ring structure may include heteroatoms other than carbon atoms and the nitrogen atoms to which they are bonded, and examples of such heteroatoms include nitrogen atoms and oxygen atoms.

[0079] Particularly preferred compounds represented by the general formula (8) are those represented by the formula R 14 and R 15 are bonded to each other to form a piperazine ring structure together with the nitrogen atom to which they are bonded. More specifically, compounds represented by the following general formula (9) are particularly preferred. By using a compound having such a structure as the compound represented by general formula (8), the fuel economy properties of the obtained cross-linked rubber can be further improved. [ka] In the above general formula (9), A 3 , R 13 , and s are the same as those in the general formula (8), and R 16 represents a hydrocarbon group.

[0080] R in the above general formula (9) 16 represents a hydrocarbon group. 16The hydrocarbon group that can be the aryl group is not particularly limited, and examples thereof include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl; alkenyl groups such as vinyl and allyl; alkynyl groups such as ethynyl and propynyl; aryl groups such as phenyl and naphthyl; and aralkyl groups such as benzyl. Among these, alkyl and aryl groups are preferred, alkyl groups are more preferred, and methyl groups are particularly preferred.

[0081] Specific examples of the compound represented by the general formula (8) include 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-diethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dimethoxy-8-(N,N-diethylamino)methyl-1,6-dioxa-2-silacyclooctane, 2-methoxy-2-methyl-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, etc. These compounds represented by the general formula (8) may be used alone or in combination of two or more.

[0082] Among the hydrocarbyloxysilane compounds, the compound represented by the general formula (7) is preferred because it can further improve the processability of the conjugated diene polymer and the wear resistance and fuel economy of the resulting cross-linked rubber in a well-balanced manner. 2 is a group containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom, and 2 However, a compound containing both a primary amino group having an active hydrogen atom and a secondary amino group having an active hydrogen atom is more preferred.

[0083] The conjugated diene polymer of the present invention has a silicon content of 95 ppm by weight or more. If the silicon content of the conjugated diene polymer is less than 95 ppm by weight, it becomes difficult to improve the processability of the conjugated diene polymer and the abrasion resistance and fuel economy of the resulting cross-linked rubber in a balanced manner.

[0084] In the conjugated diene polymer of the present invention, the silicon content is not particularly limited as long as it is 95 ppm by weight or more, but the silicon content is preferably 120 ppm by weight or more, more preferably 150 ppm by weight or more, even more preferably 200 ppm by weight or more, and particularly preferably 250 ppm by weight or more. When the silicon content is within the above range, the interaction between the conjugated diene polymer and fillers such as silica can be further enhanced, and the dispersibility of fillers such as silica can be further improved, resulting in a well-balanced improvement in the processability of the conjugated diene polymer and the wear resistance and fuel economy of the resulting cross-linked rubber.

[0085] On the other hand, a moderately low silicon content means that the molecular weight of the conjugated diene polymer is moderately high relative to the silicon content. When the molecular weight of the conjugated diene polymer is moderately high, entanglement between polymer chains of the conjugated diene polymer occurs more effectively, and the abrasion resistance of the resulting cross-linked rubber tends to be improved. Therefore, the silicon content is preferably 3000 ppm by weight or less, more preferably 2000 ppm by weight or less, and even more preferably 1000 ppm by weight or less.

[0086] Examples of methods for controlling the silicon content include a method for controlling the content of the vinyl compound unit containing the above-mentioned functional group capable of interacting with silica in the conjugated diene polymer, and a method for controlling the type and amount of the above-mentioned silicon atom-containing modifier used.

[0087] The silicon content can be measured by X-ray fluorescence analysis or alkali fusion-inductively coupled plasma atomic emission spectroscopy (ICPAES). The silicon content is preferably measured by X-ray fluorescence analysis. If the conjugated diene polymer contains impurities, an error may occur in the measured silicon content. In such a case, the conjugated diene polymer may be subjected to Soxhlet extraction or the like as necessary to remove impurities, and then the silicon content may be measured.

[0088] The conjugated diene polymer of the present invention has an ionic strength index of 75% or less.

[0089] In this specification, the ionic strength index is a value calculated according to the following formula (I) based on the results of gel permeation chromatography (GPC) measurement (hereinafter sometimes referred to as "GPC measurement") using a styrene-based column and GPC measurement using a cation exchange column, performed on a sample solution containing a conjugated diene-based polymer and internal standard polystyrene (molecular weight 5000). Ionic strength index (%) = {1-(A CX / B CX )×(B sty / A sty )}×100 (I) A CX : Peak area of ​​molecular weight distribution curve of conjugated diene polymers measured by GPC using a cation exchange column B CX : Peak area of ​​the internal standard polystyrene peak measured by GPC using a cation exchange column B sty : Peak area of ​​the internal standard polystyrene peak measured by GPC using a styrene column A sty : Peak area of ​​molecular weight distribution curve of conjugated diene polymer measured by GPC using a styrene column where A CX and A styIn the definition above, the peak area of ​​the molecular weight distribution curve of the conjugated diene polymer refers to the peak area of ​​the molecular weight distribution curve obtained by excluding the region of molecular weight less than 5,000 from the obtained molecular weight distribution curve and further excluding the peak of the internal standard polystyrene. A column using a styrene-divinylbenzene gel packing material is defined as a styrene-based column.

[0090] The GPC measurement using a styrene column and the GPC measurement using a cation exchange column can be carried out under the conditions described in the Examples below.

[0091] If the conjugated diene polymer contains impurities such as oil, an error may occur in the measured value of the ionic strength index. In such a case, the conjugated diene polymer may be subjected to Soxhlet extraction or the like as necessary to remove impurities, and then the ionic strength index may be measured.

[0092] In GPC measurement using a cation exchange column, ionic interaction occurs between some polymer chains in the conjugated diene polymer and the surface of the cation exchange column. Therefore, the greater the proportion of polymer chains in the conjugated diene polymer that cause ionic interaction and the stronger the ionic interaction of the polymer chains, the lower the peak intensity attributable to the polymer chains in the molecular weight distribution curve obtained using the cation exchange column compared to the molecular weight distribution curve obtained using a styrene column, and the larger the ionic strength index calculated by the above formula (I).

[0093] If the ionic strength index of the conjugated diene polymer is greater than 75%, the polymer chains of the conjugated diene polymer tend to aggregate excessively, which tends to result in insufficient entanglement of the polymer chains of the conjugated diene polymer, making it difficult to improve the processability of the conjugated diene polymer and the abrasion resistance and fuel economy of the resulting cross-linked rubber in a balanced manner. In particular, if the ionic strength index of the conjugated diene polymer is greater than 75%, the abrasion resistance of the resulting cross-linked rubber tends to decrease.

[0094] The lower limit of the ionic strength index is not particularly limited as long as it is 0% or more, but is preferably 0.5% or more. When the ionic strength index is within the above range, interaction between polymer chains of the conjugated diene polymer occurs appropriately, and entanglement of the polymer chains occurs more effectively, resulting in improved abrasion resistance of the obtained cross-linked rubber product.

[0095] In particular, when processability of the conjugated diene polymer is required, the processability of the conjugated diene polymer tends to be further improved by setting the upper limit of the ionic strength index to preferably 60% or less, more preferably 45% or less, even more preferably 30% or less, especially preferably 20% or less, particularly preferably 10% or less, and most preferably 5% or less.

[0096] Furthermore, in particular, when the abrasion resistance and fuel economy properties of the obtained cross-linked rubber product are required, the abrasion resistance and fuel economy properties of the obtained cross-linked rubber product tend to be further improved by setting the lower limit of the ionic strength index to more preferably 0.8% or more, even more preferably 2% or more, still more preferably 3.5% or more, especially preferably 9% or more, particularly preferably 20% or more, and most preferably 30% or more.

[0097] The ionic strength index can be controlled by adjusting the proportion of polymer chains in the conjugated diene polymer that have a functional group (for example, a cationic group such as an amino group) that interacts with a cation exchange column, the position of the functional group in the polymer chain (for example, whether in the polymer chain or at the end of the polymer chain), the molecular structure in the vicinity of the functional group, the proportion of the functional group, etc., and it is desirable to combine these appropriately.

[0098] The weight-average molecular weight (Mw) of the conjugated diene polymer of the present invention is preferably 200,000 or more. The larger the weight-average molecular weight (Mw), the more easily the polymer chains of the conjugated diene polymer become entangled, and the abrasion resistance of the resulting cross-linked rubber tends to be further improved. Furthermore, the weight-average molecular weight (Mw) of the conjugated diene polymer of the present invention is preferably 10,000,000 or less. A suitably small weight-average molecular weight (Mw) tends to suitably lower the viscosity of the conjugated diene polymer during processing, and to further improve the processability of the conjugated diene polymer. Therefore, the weight average molecular weight (Mw) is preferably in the range of 200,000 to 10 million, more preferably in the range of 350,000 to 5 million, even more preferably in the range of 400,000 to 5 million, still more preferably in the range of 500,000 to 3 million, especially preferably in the range of 500,000 to 2 million, particularly preferably in the range of 500,000 to 1.5 million, and most especially preferably in the range of 550,000 to 1.2 million.

[0099] The molecular weight distribution (Mw / Mn) of the conjugated diene polymer of the present invention is preferably 1.5 or more. The larger the Mw / Mn, the more the processability of the conjugated diene polymer and the abrasion resistance of the resulting cross-linked rubber tend to be improved. The molecular weight distribution (Mw / Mn) is more preferably 1.5 to 5, even more preferably 1.5 to 3, and particularly preferably 1.55 to 3.

[0100] The conjugated diene polymer of the present invention preferably has two or more peaks in its molecular weight distribution curve. The greater the number of peaks in the molecular weight distribution curve, the broader the molecular weight distribution tends to be, which makes it easier for the polymer chains of the conjugated diene polymer to become entangled, and the abrasion resistance of the resulting cross-linked rubber tends to be improved. The number of peaks in the molecular weight distribution curve is more preferably within the range of 2 to 6, and even more preferably within the range of 3 to 5. Examples of methods for achieving two or more peaks in the molecular weight distribution curve include, when synthesizing a conjugated diene polymer by polymerizing a monomer, adding a polymerization initiator during the polymerization and then continuing the polymerization, performing a coupling reaction on the polymer chains obtained by polymerization, and blending two or more conjugated diene polymers having different molecular weight distribution curves, preferably in the form of a polymer solution. These methods may be used in combination.

[0101] In this specification, when the number of peaks in a molecular weight distribution curve is two or more, the peak with the lowest molecular weight is defined as the first peak, and the peaks thereafter are defined in ascending order of molecular weight as the second peak, the third peak, etc. Furthermore, the molecular weight at which the molecular weight distribution curve for each peak shows a maximum value is defined as the peak top molecular weight of each peak.

[0102] In the conjugated diene polymer of the present invention, for example, when the number of peaks in the molecular weight distribution curve is three, the peak-top molecular weight of the first peak is preferably in the range of 80,000 to 1.5 million, more preferably in the range of 90,000 to 1.2 million, and even more preferably in the range of 100,000 to 800,000. The peak-top molecular weight of the second peak is preferably in the range of 150,000 to 5 million, more preferably in the range of 170,000 to 4 million, and even more preferably in the range of 200,000 to 3 million. The peak-top molecular weight of the third peak is preferably in the range of 200,000 to 5 million, more preferably in the range of 220,000 to 4 million, and even more preferably in the range of 250,000 to 3 million.

[0103] In the conjugated diene polymer of the present invention, for example, when the number of peaks in the molecular weight distribution curve is four, the peak-top molecular weight of the first peak is preferably in the range of 80,000 to 1.5 million, more preferably in the range of 90,000 to 1.2 million, and even more preferably in the range of 100,000 to 800,000. The peak-top molecular weight of the second peak is preferably in the range of 150,000 to 5 million, more preferably in the range of 170,000 to 4 million, and even more preferably in the range of 200,000 to 3 million. The peak-top molecular weight of the third peak is preferably in the range of 200,000 to 5 million, more preferably in the range of 220,000 to 4 million, and even more preferably in the range of 250,000 to 3 million. The peak-top molecular weight of the fourth peak is preferably in the range of 300,000 to 5 million, and even more preferably in the range of 400,000 to 4 million.

[0104] In the conjugated diene polymer of the present invention, for example, when the number of peaks in the molecular weight distribution curve is five, the peak-top molecular weight of the first peak is preferably in the range of 80,000 to 1.5 million, more preferably in the range of 90,000 to 1.2 million, and even more preferably in the range of 100,000 to 800,000. The peak-top molecular weight of the second peak is preferably in the range of 150,000 to 5 million, more preferably in the range of 170,000 to 4 million, and even more preferably in the range of 200,000 to 3 million. The peak-top molecular weight of the third peak is preferably in the range of 200,000 to 5 million, more preferably in the range of 220,000 to 4 million, and even more preferably in the range of 250,000 to 3 million. The peak-top molecular weight of the fourth peak is preferably in the range of 300,000 to 5 million, more preferably in the range of 400,000 to 4 million, and even more preferably in the range of 500,000 to 3 million. The peak top molecular weight of the fifth peak is preferably in the range of 400,000 to 5,000,000, more preferably in the range of 500,000 to 4,000,000, and even more preferably in the range of 600,000 to 3,000,000.

[0105] The weight-average molecular weight (Mw), molecular weight distribution (Mw / Mn), number of peaks in a molecular weight distribution curve, and peak-top molecular weight of each peak can be measured by the following method. First, a sample solution containing a conjugated diene polymer and an internal standard polystyrene is subjected to GPC measurement using a styrene column, similar to the measurement of the ionic strength index described above, to obtain a molecular weight distribution curve of the conjugated diene polymer. Based on the obtained molecular weight distribution curve of the conjugated diene polymer, the polystyrene-equivalent weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) can be determined. Furthermore, the obtained molecular weight distribution curve of the conjugated diene polymer is divided into regions sandwiched between the baseline or minimum values ​​and having one maximum value, and the peak area of ​​each divided region is determined. When the peak area of ​​the entire molecular weight distribution curve of the conjugated diene polymer is taken as 100%, the number of regions having a peak area of ​​1% or more can be determined as the number of molecular weight peaks. Furthermore, for the peaks in each divided region (limited to regions with a peak area of ​​1% or more), the peak in the region with the lowest molecular weight is defined as the first peak, and the peaks after the first peak are defined as the second peak, third peak, etc. in order of decreasing molecular weight, and the peak top molecular weight of each peak (the molecular weight showing the maximum value in each region) can be determined.

[0106] The conjugated diene polymer of the present invention preferably has a Mooney viscosity (ML1+4) value of 10 or more and 200 or less, more preferably 20 or more and 150 or less, even more preferably 30 or more and 145 or less, particularly preferably 40 or more and 140 or less, and most preferably 50 or more and 135 or less. When the Mooney viscosity is within the above range, processability is improved. The Mooney viscosity (ML1+4) is measured at 100°C in accordance with JIS K6300-1:2013.

[0107] From the viewpoint of ease of handling, the conjugated diene polymer of the present invention can be suitably used in a state mixed with an extender oil, which will be described later. When the conjugated diene polymer is used in a state mixed with an extender oil, the Mooney viscosity (ML1+4) of the conjugated diene polymer mixed with the extender oil can be determined as the Mooney viscosity (ML1+4) of the conjugated diene polymer. In this case, the suitable range and measurement conditions for the Mooney viscosity (ML1+4) are the same as those described above.

[0108] <Method of producing conjugated diene polymer> The conjugated diene polymer of the present invention can be obtained, for example, by polymerizing a monomer mixture containing at least a conjugated diene monomer in an inert solvent using a polymerization initiator. The conjugated diene polymer of the present invention is preferably polymerized by a solution polymerization method.

[0109] The conjugated diene monomer contained in the monomer mixture may be the same as the conjugated diene monomers exemplified above as those usable for constituting the conjugated diene polymer. Furthermore, the monomer mixture may contain the above-mentioned aromatic vinyl monomer, a vinyl compound containing a functional group capable of interacting with silica, and other monomers, as necessary.

[0110] The inert solvent used in the polymerization is not particularly limited as long as it is one that is commonly used in solution polymerization and 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 such that the monomer concentration is, for example, 1 to 50% by weight, preferably 10 to 40% by weight.

[0111] The polymerization initiator used in the polymerization is not particularly limited as long as it can polymerize a monomer mixture containing a conjugated diene monomer. Specific examples include polymerization initiators using organic alkali metal compounds, organic alkaline earth metal compounds, and lanthanum series metal compounds as the main catalyst. Examples of organic alkali metal compounds include organolithium compounds, organosodium compounds, and organopotassium compounds. Specific examples include organomonolithium 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-trilithiobenzene, and 1,3,5-tris(lithiomethyl)benzene; organosodium compounds such as sodium naphthalene; and organopotassium 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.

[0112] Examples of organic alkali metal amide compounds include those obtained by reacting an organic alkali metal compound with a secondary amine compound, and among these, compounds represented by the following general formula (10) can be preferably used. R 17 -N(-R 18 )-M 1 (10) In general formula (10), M 1 represents an alkali metal atom, and R 17 , R 18 each independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, a protecting group for an amino group, or a group that can generate a hydroxyl group upon hydrolysis; R 17 and R 18 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 the ring structure together with, in addition to the nitrogen atom to which they are bonded, a heteroatom other than the nitrogen atom to which they are bonded.

[0113] The alkyl group is not particularly limited, but is preferably an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms. Examples of such alkyl groups include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, and an n-decyl group.

[0114] The cycloalkyl group is not particularly limited, but is preferably a cycloalkyl group having 3 to 20 carbon atoms, and more preferably a cycloalkyl group having 3 to 12 carbon atoms. Examples of such cycloalkyl groups include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and a cyclododecyl group.

[0115] The aryl group is not particularly limited, but is preferably an aryl group having 6 to 12 carbon atoms, and more preferably an aryl group having 6 to 10 carbon atoms. Examples of such aryl groups include a phenyl group, a 1-naphthyl group, and a 2-naphthyl group.

[0116] The aralkyl group is not particularly limited, but is preferably an aralkyl group having 7 to 13 carbon atoms, more preferably an aralkyl group having 7 to 9 carbon atoms. Examples of such aralkyl groups include a benzyl group and a phenethyl group.

[0117] The amino-protecting group is not particularly limited as long as it acts as a protecting group for an amino group, and examples thereof include alkylsilyl groups, etc. Examples of such alkylsilyl groups include trimethylsilyl, triethylsilyl, triphenylsilyl, methyldiphenylsilyl, ethylmethylphenylsilyl, and tert-butyldimethylsilyl.

[0118] In addition, R 17 , and / or R 18 is a protecting group for an amino group, the protecting group for the amino group is removed, and the resulting conjugated diene polymer is formed at one end of the polymer chain by removing the protecting group for the amino group. 19 , and / or R 20 It is possible to introduce a structure in which is a hydrogen atom.

[0119] The group that can be hydrolyzed to generate a hydroxyl group is not particularly limited, and may be, for example, a group that generates a hydroxyl group when hydrolyzed in the presence of an acid or the like, and examples thereof include an alkoxyalkyl group and a group containing an epoxy group.

[0120] Examples of the alkoxyalkyl group include a methoxymethyl group, an ethoxymethyl group, an ethoxyethyl group, a propoxymethyl group, a butoxymethyl group, a butoxyethyl group, and a propoxyethyl group.

[0121] Examples of the group containing an epoxy group include a group represented by the following general formula (11). -Z 3 -Z 4 -E 2 (11) In general formula (11), Z 3 is an alkylene group or alkylarylene group having 1 to 10 carbon atoms, and Z 4 is a methylene group, a sulfur atom, or an oxygen atom, and E 2 is a glycidyl group.

[0122] Also, R 17 and R 18 may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, and in this case, R 17 and R 18 and a nitrogen atom bonded thereto, an azetidine ring (R 17 and R 18 propylene group), pyrrolidine ring (R 17 and R 18 butylene group), piperidine ring (R 17 and R 18 pentylene group), hexamethyleneimine ring (R 17 and R 18 (hexylene group) etc. 17 and R 18 When they bond to each other to form a ring structure together with the nitrogen atom to which they are bonded, the ring structure is preferably a 4- to 8-membered ring structure.

[0123] In addition, in the general formula (10), M 1 is an alkali metal atom, and examples of such alkali metal atoms include lithium, sodium, and potassium atoms. Among these, lithium atoms are preferred from the viewpoint of polymerization activity.

[0124] When the compound represented by the general formula (10) is used as a polymerization initiator, the amine structure forming the organic alkali metal amide compound remains bonded to the polymerization initiation terminal of the polymer chain. Therefore, when the compound represented by the general formula (10) is used as a polymerization initiator, a structure represented by the following general formula (12) is introduced at one terminal of the polymer chain forming the obtained conjugated diene polymer. R 19 -N(-R 20 )- (12) In general formula (12), R 19 , R 20 each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, a protecting group for an amino group, or a group that can be hydrolyzed to generate a hydroxyl group; R 19 and R 20 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 the ring structure together with, in addition to the nitrogen atom to which they are bonded, a heteroatom other than the nitrogen atom to which they are bonded.

[0125] R 19 , R 20 Examples of the alkyl group, cycloalkyl group, aryl group, aralkyl group, protecting group for amino group, or group capable of generating a hydroxyl group upon hydrolysis include R 17 , R 18 and R 19 and R 20 are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded. 17 , R 18 It can be the same as R19 , R 20 The hydrogen atom capable of becoming the hydroxyl group is introduced by removing the protecting group of the amino group.

[0126] The method for adding an organic alkali metal amide compound as a polymerization initiator to a polymerization system is not particularly limited. For example, an organic alkali metal compound may be reacted with a secondary amine compound in advance to obtain an organic alkali metal amide compound, which is then mixed with a monomer containing a conjugated diene monomer to allow the polymerization reaction to proceed. Alternatively, an organic alkali metal compound and a secondary amine compound may be added separately to the polymerization system, and then mixed with a monomer containing a conjugated diene monomer to generate an organic alkali metal amide compound in the polymerization system, thereby allowing the polymerization reaction to proceed. The reaction conditions, such as the reaction temperature, are not particularly limited and may be determined according to the desired polymerization reaction conditions, for example.

[0127] The amount of the secondary amine compound used may be determined depending on the amount of the polymerization initiator to be added, but is usually in the range of 0.01 to 1.5 mmol, preferably 0.1 to 1.2 mmol, and more preferably 0.5 to 1.0 mmol per 1 mmol of the organic alkali metal compound.

[0128] The amount of the polymerization initiator used may be determined depending on the molecular weight distribution curve of the target conjugated diene polymer, but is usually in the range of 1 to 50 mmol, preferably 1.5 to 20 mmol, and more preferably 2 to 15 mmol per 1000 g of monomer.

[0129] After initiating polymerization using a polymerization initiator, a polymerization initiator supplementation operation may be performed by adding additional polymerization initiator 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 target conjugated diene polymer. The amount of polymerization initiator used per supplementation operation is not particularly limited, but is preferably 0.1 to 0.7 mol, more preferably 0.2 to 0.6 mol, per mol of polymerization initiator used at the start of polymerization.

[0130] 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.

[0131] Furthermore, when polymerizing a monomer mixture containing a conjugated diene monomer, it is preferable to add a polar compound to an inert organic solvent to adjust the vinyl bond content in the conjugated diene monomer units in the resulting conjugated diene-based polymer. Examples of polar compounds include ether compounds such as ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 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 ethylene glycol diethyl ether, ethylene glycol dibutyl ether, and tertiary amines being more preferred, and tertiary amines being even more preferred, with tetramethylethylenediamine being particularly 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 1 mol of polymerization initiator. When the amount of the polar compound used is within this range, it is easy to adjust the vinyl bond content in the conjugated diene monomer unit, and problems due to deactivation of the polymerization initiator are unlikely to occur.

[0132] The conjugated diene polymer of the present invention may be obtained by a production method comprising the steps of: polymerizing a monomer (a) containing isoprene in an inert solvent using a polymerization initiator to form a polymer block (A) having an active end; and mixing the polymer block (A) having an active end with a monomer (b) containing 1,3-butadiene to continue the polymerization reaction, thereby providing the polymer block (A) and the polymer block (B).

[0133] By employing such a production method, the conjugated diene polymer can be one containing a polymer block (A) containing an isoprene monomer unit and a polymer block (B) containing a 1,3-butadiene monomer unit formed in a continuous manner, and as a result, the processability of the conjugated diene polymer and the abrasion resistance and fuel economy of the obtained cross-linked rubber can be further improved in a well-balanced manner.

[0134] The monomer (a) for forming the polymer block (A) may be any monomer containing isoprene, and a monomer appropriate for the monomer composition of the polymer block (A) to be formed may be used. For example, when the polymer block (A) is composed of isoprene monomer units and aromatic vinyl monomer units, the monomer (a) may contain isoprene and an aromatic vinyl monomer. When the polymer block (A) contains, in addition to the isoprene monomer units and aromatic vinyl monomer units, units of a vinyl compound containing a functional group capable of interacting with silica, the monomer (a) may contain, in addition to the isoprene monomer units and aromatic vinyl monomer units, a vinyl compound containing a functional group capable of interacting with silica. Such embodiments are described below.

[0135] The polymer block (A) is not particularly limited as long as it contains isoprene monomer units, 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 (A) preferably contains aromatic vinyl monomer units in addition to isoprene monomer units.

[0136] The content of isoprene monomer units in polymer block (A) is preferably 50% by weight or more, more preferably 70% by weight or more, and even more preferably 90% by weight or more. The upper limit of the content of isoprene monomer units is not particularly limited, but is preferably 99% by weight or less. By ensuring that the content of isoprene monomer units in polymer block (A) falls within the above range, when a filler such as silica is blended with the conjugated diene polymer, the affinity between the conjugated diene polymer and the filler such as silica can be further increased, thereby further improving the processability of the conjugated diene polymer and the abrasion resistance and fuel economy of the resulting cross-linked rubber in a well-balanced manner.

[0137] The aromatic vinyl monomer used to form the aromatic vinyl monomer units contained in the polymer block (A) can be the same as the aromatic vinyl monomers described above, with styrene being preferred. These aromatic vinyl monomers may be used alone or in combination of two or more. The content of the aromatic vinyl monomer units in the polymer block (A) is preferably 50% by weight or less, more preferably 30% by weight or less, and even more preferably 10% by weight or less. The lower limit of the content of the aromatic vinyl monomer units is not particularly limited, but is preferably 1% by weight or more.

[0138] Furthermore, at least one of the polymer block (A) and the polymer block (B) described below that constitute the conjugated diene polymer may contain a vinyl compound unit containing a functional group capable of interacting with silica. In this case, the vinyl compound unit containing a functional group capable of interacting with silica may be contained only in the polymer block (A), only in the polymer block (B), or both in the polymer block (A) and the polymer block (B).

[0139] The content of the vinyl compound units containing a functional group capable of interacting with silica is preferably adjusted to be 0.01 to 20 wt%, more preferably 0.02 to 2 wt%, and particularly preferably 0.03 to 1 wt%, relative to all monomer units constituting the conjugated diene polymer, whether they are contained in polymer block (A), polymer block (B), or both. By setting the content of the vinyl compound units containing a functional group capable of interacting with silica within the above range, the conjugated diene polymer can be made to have an excellent balance between processability, abrasion resistance, and fuel economy of the resulting cross-linked rubber, and handling stability can also be improved.

[0140] Polymer block (A) may optionally contain other monomer units in addition to isoprene monomer units, optionally aromatic vinyl monomer units, and vinyl compound units containing functional groups capable of interacting with silica. Examples of other compounds used to form the other monomer units include linear olefin compounds such as ethylene, propylene, and 1-butene; cyclic olefin compounds such as cyclopentene and 2-norbornene; conjugated diene monomers other than isoprene such as 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene; and non-conjugated diene monomers such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene. These other monomers may be used alone or in combination. The content of other monomer units in the polymer block (A) is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 6% by weight or less.

[0141] The polymer block (A) is formed by polymerizing the isoprene-containing monomer (a) in an inert solvent with a polymerization initiator. The formed polymer block (A) has an active terminal.

[0142] The inert solvent used in the polymerization of the monomers to form the polymer block (A) may be the same as the inert solvent described above. The amount of the inert solvent used is such that the monomer concentration is preferably 1 to 80% by weight, more preferably 10 to 50% by weight.

[0143] The polymerization initiator used to form the polymer block (A) is not particularly limited as long as it can polymerize the isoprene-containing monomer (a) to give a polymer chain having an active terminal. Specific examples of the polymerization initiator include the same initiators as those described above.

[0144] The amount of the polymerization initiator used may be determined depending on the target molecular weight, but is preferably in the range of 4 to 250 mmol, more preferably 6 to 200 mmol, and particularly preferably 10 to 70 mmol, per 100 g of the isoprene-containing monomer (a).

[0145] The polymerization temperature during polymerization of the isoprene-containing monomer (a) is preferably in the range of -80 to +150°C, more preferably 0 to 100°C, and even more preferably 20 to 90°C. The polymerization method may be any method, such as batch or continuous. Furthermore, when the polymer block (A) is formed into a copolymer chain, the bonding method of each monomer may be various, such as block, tapered, or random.

[0146] In addition, in order to adjust the vinyl bond content in the isoprene monomer units in the polymer block (A), it is preferable to add a polar compound to the inert solvent during polymerization. The same polar compounds as those described above can be used as the polar compound. The amount of the polar compound used can be determined depending on the target vinyl bond content, and is preferably 0.01 to 30 mol, more preferably 0.05 to 10 mol, per mol of the polymerization initiator. When the amount of the polar compound used is within the above range, it is easy to adjust the vinyl bond content in the isoprene monomer units, and problems due to deactivation of the polymerization initiator are unlikely to occur. Furthermore, by increasing the amount of the polar compound used within the above range, the vinyl bond content in the isoprene monomer units can be increased.

[0147] The vinyl bond content in the isoprene monomer units in the polymer block (A) is preferably 5 to 90% by weight, more preferably 5 to 80% by weight. By setting the vinyl bond content in the isoprene monomer units within the above range, the fuel economy properties of the obtained cross-linked rubber can be further improved. In this specification, the vinyl bond content in the isoprene monomer units refers to the proportion of the total amount of isoprene monomer units having a 1,2-structure and isoprene monomer units having a 3,4-structure in the isoprene monomer units.

[0148] The weight average molecular weight (Mw) of the polymer block (A) is preferably in the range of 1,000 to 30,000, more preferably in the range of 1,500 to 20,000, and even more preferably in the range of 2,000 to 10,000. By setting the weight average molecular weight (Mw) of the polymer block (A) in the above range, the fuel economy properties of the obtained cross-linked rubber can be further improved.

[0149] The molecular weight distribution of the polymer block (A), represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.0 to 1.5, more preferably 1.0 to 1.3. When the molecular weight distribution value (Mw / Mn) of the polymer block (A) is within the above range, production of the conjugated diene polymer becomes easier. The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer block (A) can be determined as polystyrene-equivalent values ​​by gel permeation chromatography.

[0150] The polymer block (B) 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 (B) contains aromatic vinyl monomer units in addition to 1,3-butadiene monomer units.

[0151] The content of 1,3-butadiene monomer units in the polymer block (B) is preferably 45% by weight or more, more preferably 50 to 94.98% by weight, and even more preferably 55 to 89.97% by weight. By setting the content of 1,3-butadiene monomer units in the polymer block (B) within the above range, production of the conjugated diene polymer becomes easier.

[0152] The aromatic vinyl monomer used to form the aromatic vinyl monomer units contained in polymer block (B) can be the same as the aromatic vinyl monomers described above, and among these, styrene is preferred. The content of the aromatic vinyl monomer units is preferably 54.99% by weight or less, more preferably 5 to 49.98% by weight, and even more preferably 10 to 44.97% by weight.

[0153] It is also preferred that at least one of the polymer block (A) and the polymer block (B) contains units of a vinyl compound containing a functional group capable of interacting with silica.From the viewpoint of achieving a conjugated diene polymer with a better balance between processability and the abrasion resistance and fuel economy of the resulting cross-linked rubber, it is more preferred that at least the polymer block (B) contains units of a vinyl compound containing a functional group capable of interacting with silica.When the polymer block (B) contains units of a vinyl compound containing a functional group capable of interacting with silica, the content ratio thereof is not particularly limited, but it is preferred that the content ratio relative to all monomer units constituting the finally obtained conjugated diene polymer of the present invention be within the above-mentioned preferred range.

[0154] Furthermore, polymer block (B) may optionally contain other monomer units in addition to 1,3-butadiene monomer units, and optionally aromatic vinyl monomer units and vinyl compound units containing functional groups capable of interacting with silica. Examples of other compounds constituting such other monomer units include the same compounds exemplified for polymer block (A) above (excluding 1,3-butadiene) as well as isoprene. The content of other monomer units in polymer block (B) is preferably 40% by weight or less, more preferably 35% by weight or less, and even more preferably 25% by weight or less.

[0155] Polymer block (B) is formed continuously with polymer block (A) by mixing polymer block (A) having the above-mentioned active terminal with monomer (b) containing 1,3-butadiene and continuing the polymerization reaction. The formed polymer block (B) has an active terminal. Meanwhile, the active terminal disappears from polymer block (A).

[0156] The inert solvent used in the polymerization of the polymer block (A) with the monomer (b) containing 1,3-butadiene to form the polymer block (B) is not particularly limited, and the same inert solvents as those described above can be used.

[0157] The amount of polymer block (A) having an active end used in forming polymer block (B) may be determined depending on the target molecular weight, but is preferably in the range of 0.1 to 5 mmol, more preferably 0.15 to 2 mmol, and even more preferably 0.2 to 1.5 mmol per 100 g of monomer (b) containing 1,3-butadiene.

[0158] The method for mixing the polymer block (A) and the monomer (b) containing 1,3-butadiene is not particularly limited, and the polymer block (A) having an active end may be added to a solution of the monomer (b) containing 1,3-butadiene, or the monomer (b) containing 1,3-butadiene may be added to a solution of the polymer block (A) having an active end. From the viewpoint of controlling the polymerization, the method of adding the polymer block (A) having an active end to a solution of the monomer (b) containing 1,3-butadiene is preferred.

[0159] The polymerization temperature when polymerizing the monomer (b) containing 1,3-butadiene is preferably in the range of -80 to +150°C, more preferably 0 to 100°C, and even more preferably 20 to 90°C. Any polymerization method, such as a batch method or a continuous method, can be used. When the polymer block (B) is a copolymer chain, a batch method is preferred because it is easy to control the randomness of bonding.

[0160] When the polymer block (B) is a copolymer chain, the bonding pattern of each monomer can be various, such as a block, tapered, or random bonding pattern. Among these, a random bonding pattern is preferred. By using a random bonding pattern, the fuel economy properties of the resulting cross-linked rubber can be further improved.

[0161] In one embodiment of the present invention, in order to adjust the vinyl bond content in the 1,3-butadiene monomer units in the polymer block (B), it is preferable to add a polar compound to the inert solvent during polymerization, as in the case of adjusting the vinyl bond content in the isoprene monomer units in the polymer block (A). However, if a polar compound is added to the inert solvent in an amount sufficient to adjust the vinyl bond content in the 1,3-butadiene monomer units in the polymer block (B) during the preparation of the polymer block (A), it is not necessary to add an additional polar compound. The polar compound used to adjust the vinyl bond content can be the same as the polar compounds described above. The amount of the polar compound used can be determined depending on the desired vinyl bond content, and is adjusted within a range of preferably 0.01 to 100 mol, more preferably 0.1 to 30 mol, per mol of the polymerization initiator used in the initial polymerization reaction (the polymerization reaction to form the first polymer block (A)). When the amount of the polar compound used is within this range, it is easy to adjust the vinyl bond content in the 1,3-butadiene monomer units, and problems due to deactivation of the polymerization initiator are unlikely to occur.

[0162] The vinyl bond content in the 1,3-butadiene monomer units in the polymer block (B) is preferably 1 to 90% by weight, more preferably 3 to 80% by weight, and particularly preferably 5 to 75% by weight. By setting the vinyl bond content in the 1,3-butadiene monomer units in the polymer block (B) within the above range, the obtained cross-linked rubber product can be made to have even more excellent fuel economy properties.

[0163] In this manner, a polymer chain having an active end, which includes polymer block (A) and polymer block (B), can be obtained. From the viewpoint of productivity, the polymer chain having an active end is preferably composed of polymer block (A)-polymer block (B), and the terminal of polymer block (B) is the active terminal. However, the polymer chain may have multiple polymer blocks (A) or other polymer blocks. For example, a polymer chain having an active end may be polymer block (A)-polymer block (B)-polymer block (A). In this case, the active terminal is formed at the terminal of polymer block (A) formed subsequent to polymer block (B). When polymer block (A) is formed at the active terminal side of a conjugated diene polymer, the amount of isoprene used is preferably 10 to 100 mol, more preferably 15 to 70 mol, and particularly preferably 20 to 35 mol, per mol of the polymerization initiator used in the initial polymerization reaction (polymerization reaction to form the first polymer block (A)).

[0164] The weight ratio of polymer block (A) to polymer block (B) in the polymer chain having an active end (when a plurality of polymer blocks (A) and (B) are present, the weight ratio is based on the total weight of the respective polymer blocks) is (weight of polymer block (A)) / (weight of polymer block (B)), and is preferably 0.001 to 0.2, more preferably 0.005 to 0.1, and particularly preferably 0.01 to 0.05. By setting the weight ratio of polymer block (A) to polymer block (B) within the above range, the conjugated diene polymer can be made to have an excellent balance between processability, abrasion resistance, and fuel economy of the resulting cross-linked rubber.

[0165] In this manner, a conjugated diene polymer can be obtained in an inert solvent. The conjugated diene polymer thus obtained usually has an active terminal.

[0166] A conjugated diene polymer having an active terminal may be reacted with a coupling agent to form a coupling polymer chain. The coupling agent is not particularly limited, but examples thereof include 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. Among these, from the viewpoint of being able to improve the mechanical properties of the resulting cross-linked rubber while sufficiently maintaining the processability of the conjugated diene polymer, it is preferable to use a trifunctional or higher coupling agent, and it is more preferable to use a tetrafunctional or higher coupling agent.

[0167] When using a coupling agent, it is preferable to perform a coupling reaction on a portion of the polymer chains having active ends obtained by the above-mentioned polymerization method to form coupled polymer chains, thereby obtaining a solution containing the polymer chains having active ends and the coupled polymer chains. In this case, the amount of coupling agent used is not particularly limited. However, from the viewpoint of easily performing the coupling reaction on only a portion of the polymer chains having active ends, it is preferable that the amount of coupling agent used is less than 1 mole, preferably 0.01 to 0.4 moles, and more preferably 0.02 to 0.3 moles, calculated as functional groups of the coupling agent per mole of the polymerization initiator used at the start of polymerization. By using the coupling agent in the above range, the fuel economy properties of the resulting cross-linked rubber product can be further improved. 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 coupled polymer chains disappear, leaving them without any active ends.

[0168] After the coupling reaction is carried out on a part of the polymer chains having active ends, it is preferable to further polymerize a monomer containing a conjugated diene compound on the polymer chains having active ends other than the polymer chains that have been subjected to the coupling reaction. These reactions are preferably carried out continuously, and specifically, a preferred embodiment is one in which, after the polymerization is initiated, a coupling reaction is carried out by adding a coupling agent while the polymerization reaction is continued, and then a polymerization reaction after the coupling reaction is carried out.

[0169] The monomer used in the polymerization after the coupling reaction may contain at least a conjugated diene monomer. However, from the viewpoint of forming a conjugated diene-based polymer having conjugated diene monomer units and aromatic vinyl monomer units, it is preferable to use a monomer containing an aromatic vinyl monomer. Furthermore, in the polymerization after the coupling reaction, it is preferable to use a monomer containing a vinyl compound containing a functional group capable of interacting with silica. By using a vinyl compound containing a functional group capable of interacting with silica, it is possible to preferentially introduce units of the vinyl compound containing a functional group capable of interacting with silica into polymer chains other than the polymer chains that have undergone the coupling reaction. This effectively increases the silica adsorption rate of polymer chains other than the polymer chains that have undergone the coupling reaction, resulting in improved processability and improved fuel economy of the resulting cross-linked rubber.

[0170] Furthermore, polymerization after the coupling reaction may be carried out in an inert solvent, and the inert solvent is not particularly limited, and the same inert solvents as those described above can be used. The polymerization temperature and polymerization mode are also not particularly limited, and the same polymerization temperature and polymerization mode as those described above can be used. The bonding mode of each monomer can be various, such as block, tapered, and random bonding modes. Among these, the random bonding mode is preferred. By using a random bonding mode, the fuel economy properties of the resulting cross-linked rubber can be further improved.

[0171] Furthermore, it is preferable to carry out an additional addition operation of the polymerization initiator at the start of polymerization after the coupling reaction or during the polymerization. The timing of additional addition of the polymerization initiator and the number of times the additional addition operation of the polymerization initiator is carried out are not particularly limited and may be determined depending on the molecular weight distribution of the conjugated diene polymer to be obtained. The amount of the polymerization initiator added in the additional addition operation is not particularly limited, but is preferably 0.1 to 0.7 mol, more preferably 0.2 to 0.6 mol, per mol of the polymerization initiator used at the start of polymerization.

[0172] Furthermore, from the viewpoint of making the effects of the present invention more pronounced, it is preferable to convert the conjugated diene polymer into a conjugated diene polymer having a modifying group (modified conjugated diene polymer) by reacting a modifying agent with the active terminal contained in the conjugated diene polymer obtained by polymerization, or with the active terminal that can be contained in the conjugated diene polymer after the coupling reaction. As the modifying agent, the above-mentioned modifiers for forming the modifying group that can be contained in the conjugated diene polymer of the present invention can be used. Note that by using a modifier that can exhibit a coupling effect (for example, polyorganosiloxane) as the modifier, the number of peaks in the molecular weight distribution curve of the conjugated diene polymer can be controlled.

[0173] When a siloxane compound is used as a modifier, it is preferable to react a polymer chain having an active terminal with the siloxane compound and an organometallic compound, thereby improving the processability of the conjugated diene polymer. Examples of the organometallic compound used in this case include organic alkali metal compounds, such as organolithium compounds, organosodium compounds, and organopotassium 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-trilithiobenzene, and 1,3,5-tris(lithiomethyl)benzene; organic sodium compounds such as sodium naphthalene; and organic potassium compounds such as potassium naphthalene. Among these organometallic compounds, n-butyllithium is preferably used. The amount of the organometallic compound used in this case is preferably 0.05 to 10 moles, more preferably 0.01 to 5 moles, per mole of the siloxane compound used. When the amount of the organometallic compound used is within the above range, the conjugated diene polymer can be made to have even better processability. The organometallic compounds may be used alone or in combination of two or more.

[0174] The method of reacting a polymer chain having an active terminal with a siloxane compound and an organometallic compound includes, for example, a method of mixing a polymer chain having an active terminal with a siloxane compound and then mixing the organometallic compound, a method of mixing a polymer chain having an active terminal with an organometallic compound and then mixing the siloxane compound, and a method of simultaneously adding a siloxane compound and an organometallic compound to a polymer chain having an active terminal (or adding a siloxane compound and an organometallic compound successively) and mixing them.From the viewpoint of further improving the processability of the conjugated diene polymer, the method of mixing a polymer chain having an active terminal with an organometallic compound and then mixing the siloxane compound is preferred.

[0175] In a method of mixing a polymer chain having an active terminal with an organometallic compound and then mixing a siloxane compound, a simple and preferred method is to add the organometallic compound to the polymerization solution used for polymerization to obtain the polymer chain having an active terminal, mix them, and then add the siloxane compound to the mixed solution. In this case, the organometallic compound is preferably dissolved in an inert solvent and added to the polymerization solution, and the solution concentration is preferably in the range of 1 to 50 wt%. The temperature at which the organometallic compound is added is not particularly limited, but is usually 0 to 120°C.

[0176] There are no particular limitations on the timing of adding the organometallic compound to the solution containing polymer chains having active ends. However, from the viewpoint of increasing the reactivity of the siloxane compound in the presence of the organometallic compound, it is desirable to add the organometallic compound to the solution after the polymerization conversion rate has reached preferably 90% or more, more preferably 95% or more, and it is also desirable to add the organometallic compound to the solution when the monomer concentration has reached 5000 ppm or less.

[0177] When adding a siloxane compound to a solution containing a polymer chain having an active terminal and an organometallic compound, the siloxane compound is preferably dissolved in an inert solvent and added to the polymerization system, and the solution concentration is preferably in the range of 1 to 50 wt %. The reaction temperature when reacting the siloxane compound is not particularly limited, but is usually 0 to 120°C, and the reaction time is also not particularly limited, but is usually 1 to 60 minutes.

[0178] The timing of adding the siloxane compound to the solution containing the polymer chain having an active terminal and the organometallic compound is not particularly limited as long as it is after the organometallic compound has been added to the solution containing the polymer chain having an active terminal, but it is desirable to add the organometallic compound to the solution containing the polymer chain having an active terminal, mix for preferably 1 to 180 minutes, more preferably 5 to 60 minutes, and even more preferably 10 to 30 minutes, and then add the siloxane compound to this solution. Adding the siloxane compound in this manner can further improve the processability of the conjugated diene polymer.

[0179] The conjugated diene polymer after reaction, which is obtained by mixing a polymer chain having an active end with an organometallic compound and then mixing a siloxane compound, includes a polymer chain in which a modified structure by a siloxane compound has been introduced at the end of the polymer chain and which has been further reacted with an organometallic compound. However, in addition to this, it may also include an unmodified conjugated diene polymer chain that has not been modified with a siloxane compound, or a siloxane-modified conjugated diene polymer chain that has not been reacted with an organometallic compound.

[0180] The amount of the modifier used when reacting the active terminal of the conjugated diene polymer with the modifier is not particularly limited, but is preferably 0.01 to 10.0 mol, more preferably 0.02 to 5.0 mol, and particularly preferably 0.05 to 2.0 mol, relative to 1 mol 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 relative to 1 mol of the metal atom in the organic alkali metal compound). The modifiers may be used alone or in combination of two or more.

[0181] The method for reacting the active terminal of the conjugated diene polymer with the modifier is not particularly limited, but examples include mixing the polymer chain having the active terminal with the modifier in a solvent capable of dissolving them. Examples of the solvent used in this process include those exemplified above as solvents used in the polymerization of the conjugated diene polymer. A simple and preferred method is to leave the polymer chain having the active terminal obtained above in the polymerization solution used for the polymerization and add the modifier to the solution. The modifier may be dissolved in the inert solvent used in the polymerization and added to the polymerization system, with the solution concentration preferably in the range of 1 to 50% by weight. The reaction temperature is not particularly limited, but is typically 0 to 120°C. The reaction time is not particularly limited, but is typically 1 minute to 1 hour.

[0182] The timing of adding the modifier to the solution containing the polymer chains having active terminals 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 terminals also contains a monomer, more specifically, when the solution containing the polymer chains having active terminals contains 100 ppm or more, more preferably 300 to 50,000 ppm of the monomer. By adding the modifier in this manner, it is possible to suppress side reactions between the polymer chains having active terminals and impurities contained in the polymerization system, and to effectively control the reaction.

[0183] 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 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.

[0184] If desired, an antioxidant such as a phenol-based stabilizer, a phosphorus-based stabilizer, or a sulfur-based stabilizer may be added to the solution of the conjugated diene polymer obtained by the above method. The amount of antioxidant added may be determined appropriately depending on the type of antioxidant. Furthermore, if desired, an extender oil may be blended to form an oil-extended rubber. Examples of extender oils include paraffinic, aromatic, and naphthenic petroleum-based softeners, vegetable-based softeners, and fatty acids. When a petroleum-based softener is used, it is preferable that the polycyclic aromatic content extracted by the IP346 method (the testing method of The Institute Petroleum, UK) is less than 3%. When an extender oil is used, the amount used is typically 5 to 100 parts by weight per 100 parts by weight of the conjugated diene polymer.

[0185] The conjugated diene polymer thus obtained can be separated from the reaction mixture by removing the solvent using any method, such as steam stripping or a method of heating the mixed liquid under reduced pressure, to obtain a solid conjugated diene polymer.

[0186] 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 of 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.

[0187] <Rubber composition> The rubber composition of the present invention is a composition containing the above-mentioned conjugated diene polymer of the present invention and a filler.

[0188] The rubber composition of the present invention may contain a polymer other than the above-described conjugated diene-based polymer of the present invention. 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, which are not conjugated diene polymers as mentioned above. Among these, natural rubber, polyisoprene rubber, polybutadiene rubber, and solution-polymerized styrene-butadiene copolymer rubber are preferred. Natural rubber is 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.

[0189] In the rubber composition of the present invention, the conjugated diene polymer of the present invention preferably accounts for 10 to 100% by weight, and particularly preferably 50 to 100% by weight, of the polymer components in the rubber composition. By including the conjugated diene polymer of the present invention in the polymer components in such a ratio, the processability of the rubber composition and the balance of the abrasion resistance and fuel economy properties of the resulting cross-linked rubber can be improved.

[0190] 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 being able to further improve the abrasion resistance of the resulting cross-linked rubber. These can be used alone or in combination of two or more.

[0191] 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 170m 2 The pH of the silica is preferably 5 to 10.

[0192] As the silica, various commercially available silicas can be used, for example, "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.

[0193] 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.

[0194] 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. By setting the blending amount of filler within the above range, the processability of the rubber composition can be ensured sufficiently, and the fuel economy and fuel efficiency properties of the resulting cross-linked rubber can be further improved in a balanced manner.

[0195] The rubber composition of the present invention may further contain a silane coupling agent from the viewpoint of further improving the fuel economy characteristics of the resulting cross-linked rubber. The silane coupling agent is not particularly limited, and various silane coupling agents can be used. 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 the silane coupling agent include bis(3-(triethoxysilyl)propyl)disulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-(triethoxysilyl)propyl)tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-[ Examples of suitable silanes include ethoxybis(3,6,9,12,15-pentaoxaoctacosan-1-yloxy)silyl)-1-propanethiol, 3-octanoylthio-1-propyl-triethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, γ-trimethoxysilylpropylbenzothiazyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-thiocyanatepropyltriethoxysilane, 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, NXT-Z45, 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. Alternatively, one or more of these silane coupling agents can 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, based on 100 parts by weight of the filler.

[0196] The rubber composition of the present invention preferably further contains a crosslinking agent. 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. Among these, sulfur is preferably used. The amount of crosslinking agent added 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.

[0197] Furthermore, in addition to the above components, the rubber composition of the present invention may contain compounding agents such as a crosslinking accelerator, a crosslinking activator, an antioxidant, an activator, a process oil, a plasticizer, a lubricant, and a tackifier in the required amounts, according to a conventional method.

[0198] 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 components in the rubber composition.

[0199] Examples of crosslinking activators include higher fatty acids such as stearic acid, zinc oxide, etc. These crosslinking activators may be used alone or in combination of two or more. The amount of crosslinking activator added is preferably 0.05 to 20 parts by weight, and particularly preferably 0.5 to 15 parts by weight, per 100 parts by weight of the polymer component in the rubber composition.

[0200] To obtain the 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 a conjugated diene polymer, and then the kneaded mixture is mixed with thermally unstable components such as crosslinking agents and crosslinking accelerators to obtain the desired composition. The kneading temperature for the components excluding thermally unstable components and the conjugated diene polymer 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 usually cooled to 100°C or below, preferably 80°C or below, before being mixed with the thermally unstable components.

[0201] <Rubber cross-linked products> The cross-linked rubber product of the present invention is obtained by cross-linking the above-mentioned rubber composition of the present invention.

[0202] The cross-linked rubber product of the present invention can be produced by using the rubber composition of the present invention, for example, molding it into a desired shape using a molding machine such as an extruder, injection molding machine, compressor, or roll, and then heating it to cause a cross-linking reaction, thereby fixing 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.

[0203] 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.

[0204] 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.

[0205] The cross-linked rubber product of the present invention obtained in this manner is obtained using the conjugated diene polymer of the present invention described above, and therefore has excellent fuel economy and abrasion resistance. 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 components such as cap treads, base treads, carcasses, sidewalls, and bead portions; 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 fuel economy and abrasion resistance. [Example]

[0206] The present invention will be described below in more detail based on examples, but the present invention is not limited to these examples. In each example, "parts" and "%" are by weight unless otherwise specified. Various measurements and evaluations were carried out according to the following methods.

[0207] <Content of styrene units, vinyl bond amount> The content of styrene units (wt%) and the amount of vinyl bonds (mol%) in the conjugated diene monomer units are determined according to JIS K6239 (2007). 1 The values ​​were determined by H-NMR.

[0208] <Styrene block ratio> The styrene block ratio as the aromatic vinyl monomer block ratio was measured by H-NMR using deuterated chloroform as a solvent with reference to the following literature: The peaks at 6.1 to 7.7 ppm in the obtained H-NMR spectrum were considered to be those attributable to styrene, and of these, the peaks at 6.1 to 6.88 ppm were considered to be those attributable to styrene blocks. The ratio of the peak area attributable to styrene blocks to the peak area attributable to styrene was calculated, and this value was multiplied by 2.5 to express it as a percentage, which was the styrene block ratio. Reference: Sardelis, K. Michels, HJ Allen, G. Polymer, 1984, 25, 1011

[0209] <Mooney viscosity of conjugated diene polymer> The Mooney viscosity (ML1+4) of the conjugated diene polymer was measured in accordance with JIS K 6300-1:2013 under the following conditions. Test temperature: 100℃ Rotor type: L-shaped Testing equipment used: Shimadzu Mooney Viscometer SMV-300J, manufactured by Shimadzu Corporation

[0210] <Silicon content> The silicon content was measured by X-ray fluorescence measurement of press-molded sheets obtained by press-molding the conjugated diene polymers (A) to (L). The press-molding conditions and X-ray fluorescence measurement conditions were as follows:

[0211] (Press molding conditions) Using a Shinto Metal Industries compression molding machine (model AYSR-10), the conjugated diene polymer was heated at 150°C without pressure for 5 minutes, then subjected to 20 cycles of 5-minute hot-press presses at 150°C and a maximum pressure of 5 MPa, followed by rapid cooling at 25°C without pressure to obtain a press-molded sheet (diameter 25 mm, thickness 30 mm). To prevent the conjugated diene polymers (A) to (L) from coming into contact with the metal, a mold covered with a PTFE film (Naflon Tape TOMBO9001, manufactured by Nichias) was used for press molding. (Fluorescent X-ray measurement conditions) For the X-ray fluorescence measurement, an X-ray fluorescence analyzer (ZSX Primus II, manufactured by Rigaku) ​​was used. The press-molded sheet was placed in a sample holder, and a film (Ultra-Polyester, thickness 1.5 μm, manufactured by Chemplex Industries) was attached to the measurement surface. The obtained sample was subjected to X-ray fluorescence measurement under the following conditions, and the silicon content was determined based on the following calibration curve. (i) Measurement conditions: X-ray tube Rh 30kV 100mA Aperture φ20mm (ii) Measurement atmosphere: vacuum (iii) Calibration curve Polyethylen Reference Materials (RRM-PE-01, manufactured by Rigaku Corporation) were used as the standard sample for the calibration curve. X-ray fluorescence measurements were performed on standard samples with silicon contents of 82 ppm by weight, 544 ppm by weight, and 808 ppm by weight, and linear calibration curves were created.

[0212] <Ionic strength index> The ionic strength index was calculated according to the following formula (I) based on the results of GPC measurement using a styrene column and GPC measurement using a cation exchange column for a sample solution containing the conjugated diene polymers (A) to (L) and an internal standard polystyrene. Ionic strength index (%) = {1-(A CX / B CX )×(B sty / A sty )}×100 (I) A CX : Peak area of ​​molecular weight distribution curve of conjugated diene polymers measured by GPC using a cation exchange column B CX : Peak area of ​​the internal standard polystyrene peak measured by GPC using a cation exchange column B sty : Peak area of ​​the internal standard polystyrene peak measured by GPC using a styrene column A sty: Peak area of ​​molecular weight distribution curve of conjugated diene polymer measured by GPC using a styrene column where A CX and A sty In the definition above, the molecular weight distribution curve of a conjugated diene polymer refers to a molecular weight distribution curve obtained by excluding the region of molecular weight less than 5000 from the obtained molecular weight distribution curve and further excluding the peak of the internal standard polystyrene.

[0213] The GPC measurement using a styrene column was carried out under the following conditions. (GPC equipment and software) (i) Liquid transfer pump: LC-20AD (Shimadzu Corporation) (ii) Degasser: DGU-20A3 (Shimadzu Corporation) (iii) Autosampler: SIL-20A HT (Shimadzu Corporation) (iv) Column oven: CTO-20A (Shimadzu Corporation) (v) Refractive index detector (RID): RID-10A (Shimadzu Corporation) (vi) System controller: CBM-20A (Shimadzu Corporation) (vii) Measurement and analysis software: LC solution ver. 1.24 SP1 (viii) Measurement conditions GPC column: Plus Pore series Poly Pore 7.5mm ID x 300mm (Agilent Technologies) 2 columns Mobile phase: 25 mg of 2-(ethylamino)ethanol (Fujifilm Wako Chemical Co., Ltd., special grade) added to 3 L of tetrahydrofuran (Kanto Chemical Co., Ltd., special grade, stabilizer-free) Flow rate: 1mL / min Column oven temperature: 35°C Detection: Refractive index detector (RID) RID cell temperature: 35℃ Sample solution injection volume: 100 μL GPC column calibration standard: PStQuick Kit-H (Tosoh Corporation) (ix) Sample solution preparation conditions Solvent: 5 mg of standard polystyrene A5000 (manufactured by Tosoh Corporation) with a molecular weight of 5000 was added to 20 mL of tetrahydrofuran (manufactured by Kanto Chemical Co., Ltd., special grade, stabilizer-free) as an internal standard. Sample solution concentration: 0.5 mg / mL Automatic dissolution shaker: DF-8020 (Tosoh Corporation) Dissolution conditions: 10 mg of sample and 20 mL of solvent were placed in a screw vial, sealed, and stirred at room temperature for 120 minutes at a stirring speed of 60 reciprocations per minute using a DF-8020. Filtration was carried out using a syringe equipped with a filtration filter. Filtration filter: Millex-LG, pore size 0.45 μm, hydrophilic, PTFE, filter diameter 25 mm (Merck)

[0214] The GPC measurement using a cation exchange column was carried out under the following conditions: The measurement solution used in the GPC measurement using a cation exchange column was the same as the measurement solution used in the GPC measurement using the styrene column. (GPC equipment and software) (i) Liquid transfer pump: LC-20AD (Shimadzu Corporation) (ii) Degasser: DGU-20A3 (Shimadzu Corporation) (iii) Autosampler: SIL-20A HT (Shimadzu Corporation) (iv) Column oven: CTO-20A (Shimadzu Corporation) (v) Refractive index detector (RID): RID-10A (Shimadzu Corporation) (vi) System controller: CBM-20A (Shimadzu Corporation) (vii) Measurement and analysis software: LC solution ver. 1.24 SP1 (viii) Measurement conditions GPC column: Inertcil CX (4.6 x 250 mm, GL Sciences) x 2 Mobile phase: Tetrahydrofuran (Kanto Chemical Co., Ltd., special grade, stabilizer-free) Flow rate: 0.7mL / min Column oven temperature: 35°C Detection: Refractive index detector (RID) RID cell temperature: 35℃ Sample solution injection volume: 100 μL GPC column calibration standard: PStQuick Kit-H (Tosoh Corporation) (ix) Sample solution preparation conditions Solvent: 5 mg of standard polystyrene A5000 (manufactured by Tosoh Corporation) with a molecular weight of 5000 was added to 20 mL of tetrahydrofuran (manufactured by Kanto Chemical Co., Ltd., special grade, stabilizer-free) as an internal standard. Sample solution concentration: 0.5 mg / mL Automatic dissolution shaker: DF-8020 (Tosoh Corporation) Dissolution conditions: 10 mg of sample and 20 mL of solvent were placed in a screw vial, sealed, and stirred at room temperature for 120 minutes at a stirring speed of 60 reciprocations per minute using a DF-8020. Filtration was carried out using a syringe equipped with a filtration filter. Filtration filter: Millex-LG, pore size 0.45 μm, hydrophilic, PTFE, filter diameter 25 mm (Merck)

[0215] <Weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), number of peaks in the molecular weight distribution curve, and peak top molecular weight of each peak> Sample solutions containing the conjugated diene polymers (A) to (L) and internal standard polystyrene were subjected to GPC measurement using a styrene-based column in the same manner as in the measurement of the ionic strength index described above, to obtain molecular weight distribution curves for the conjugated diene polymers. Based on the obtained molecular weight distribution curves for the conjugated diene polymers, the weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were determined. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) were calculated in terms of polystyrene. The molecular weight distribution curves for the obtained conjugated diene polymers were divided into regions sandwiched between the baseline or minimum values ​​and each having a maximum value. The peak area of ​​each divided region was determined, and the number of regions with a peak area of ​​1% or more, when the peak area of ​​the entire molecular weight distribution curve for the conjugated diene polymer was taken as 100%, was counted as the number of molecular weight peaks. Furthermore, for the peaks in each divided region (limited to regions with a peak area of ​​1% or more), the peak in the region with the lowest molecular weight was defined as the first peak, and the peaks after the first peak were defined as the second peak, third peak, etc. in order of decreasing molecular weight, and the peak top molecular weight of each peak (the molecular weight showing the maximum value in each region) was determined.

[0216] <Processability (sheet gloss)> The surface of the rubber composition sheet after the primary kneading was visually observed and evaluated as follows: strong gloss, ⊚, weak gloss, ◯, and no gloss. The stronger the gloss of the rubber composition sheet after the primary kneading, the better the processability of the conjugated diene polymer.

[0217] <Workability (cracks on sheet edges)> The sheet edge of the rubber composition sheet after the primary kneading was visually observed, and the sheet edge was evaluated as follows: ⊚ when it was smooth and not cracked, ◯ when it was uneven but not cracked, and × when it was cracked. The more cracking of the sheet edge of the rubber composition sheet after the primary kneading is suppressed, the more excellent the processability of the conjugated diene polymer is.

[0218] <Processability (silica dispersion)> The uncrosslinked rubber composition was processed to prepare test specimens measuring approximately 5 g and measuring 3 cm square. After preheating the test specimens at 100°C for 4 minutes, the storage modulus G' was measured at a dynamic strain of 0.7% and 42% using a PREMIER RPA (manufactured by ALPHA TECHNOLOGIES) at a temperature of 40°C and a frequency of 10 Hz. The difference (ΔG') between the storage modulus G' at 0.7% dynamic strain and the storage modulus G' at 42% dynamic strain was calculated. The difference (ΔG') in the storage modulus G' in each Example and Comparative Example was indexed, with the difference (ΔG') in the storage modulus G' in Example 1 being set to 100, and this index was used as the processability (silica dispersion) value. A higher processability (silica dispersion) value indicates a better dispersion state of silica contained in the uncrosslinked rubber composition and therefore superior processability of the conjugated diene polymer.

[0219] <Low fuel consumption characteristics> The cross-linked rubber sheet was punched into strips 2 mm thick and 40 mm long to obtain test specimens. The loss tangent (tan δ(60°C)) of the obtained test specimens was measured using a viscoelasticity measuring device (manufactured by Ueshima Seisakusho Co., Ltd.) under conditions of a frequency of 10 Hz, an initial extension of 10%, a strain amplitude of 2%, and a temperature of 60°C. For the loss tangent (tan δ(60°C)) in each Example and Comparative Example, an index was calculated with the loss tangent (tan δ(60°C)) in Example 1 set to 100, and this was used as the fuel economy property value. A higher fuel economy property value means that the obtained cross-linked rubber product has better fuel economy properties.

[0220] <Wear resistance> The cross-linked rubber sheet was subjected to a DIN abrasion test specified in JIS K6264-2 (2005) to measure the specific abrasion volume. For the specific abrasion volume in each example and comparative example, an index was calculated with the specific abrasion volume in Example 2 set at 100, and this was used as the abrasion resistance value. A higher abrasion resistance value means that the resulting cross-linked rubber has better abrasion resistance properties.

[0221] <Preparation of Polymer Block (A) Having Active End> An 800 ml vessel purged with nitrogen was charged with 140.8 g of cyclohexane and 3.0 mmol of tetramethylethylenediamine, followed by 30.0 mmol of n-butyllithium. Next, 113.6 g of isoprene and 9.2 g of styrene were slowly added, and the reaction was carried out for 120 minutes at 50°C to obtain polymer block (A) having an active terminal. The resulting polymer block (A) had a weight-average molecular weight (Mw) of 6,500, a molecular weight distribution (Mw / Mn) of 1.10, a styrene monomer unit content of 7.5 wt%, an isoprene monomer unit content of 92.5 wt%, and a vinyl bond content of 7.0 mol%.

[0222] <Production Example 1> A 20 L autoclave equipped with a stirrer was charged under a nitrogen atmosphere with 7956 g of industrial hexane (Sumitomo Chemical Co., Ltd., trade name: Hexane (general product), density 0.68 g / mL), 1014 g of cyclohexane, 3.08 mmol of tetramethylethylenediamine, 425 g of 1,3-butadiene, 680 g of styrene, and 4.27 mmol of piperidine. A small amount of n-butyllithium was added to the autoclave as a scavenger to detoxify impurities that could deactivate the polymerization. Then, 4.27 mmol of n-butyllithium was added, and polymerization was initiated at 55°C. The polymerization reaction was continued for 15 minutes, after which 595 g of 1,3-butadiene was added continuously over 85 minutes. After confirming that the polymerization conversion rate had reached 95% to 100%, 10 minutes later, polyorganosiloxane represented by the following formula (13) was added so that the epoxy group content was 3.42 mmol, and the reaction was allowed to proceed for 20 minutes. Two equivalents of methanol were then added to the autoclave as a polymerization terminator, based on the total amount of lithium, to obtain a solution containing a conjugated diene polymer. To this solution, 0.20 parts of 2,4-bis(octylthiomethyl)-6-methylphenol (RIANOX Corporation, trade name: RIANOX1520) were added as an antioxidant, based on 100 parts of the conjugated diene polymer, to obtain a polymer solution.

[0223] [ka]

[0224] <Production Example 2> A 20 L autoclave equipped with a stirrer was charged with 7956 g of industrial hexane, 1014 g of cyclohexane, 2.63 mmol of tetramethylethylenediamine, 425 g of 1,3-butadiene, and 680 g of styrene under a nitrogen atmosphere. To detoxify impurities that could deactivate the polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger. Then, 4.38 mmol of the polymer block (A) with active terminals obtained above (calculated as lithium atom content) was added, and the polymerization growth reaction was carried out at 55°C. After the polymerization reaction was continued for 15 minutes, 595 g of 1,3-butadiene was added continuously over 85 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 1.2 mmol of normal butyllithium was added, and after another 10 minutes, polyorganosiloxane represented by the above formula (13) was added so that the epoxy group content was 3.42 mmol, and the reaction was allowed to proceed for 20 minutes. Then, 2 equivalents of methanol relative to the total amount of lithium in the autoclave were added as a polymerization terminator to obtain a solution containing a conjugated diene polymer. To this solution, 0.20 parts of 2,4-bis(octylthiomethyl)-6-methylphenol were added as an antioxidant relative to 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0225] <Production Example 3> A 20 L autoclave equipped with a stirrer was charged with 9180 g of industrial hexane, 1170 g of cyclohexane, 5.2 mmol of tetramethylethylenediamine, 500 g of 1,3-butadiene, and 800 g of styrene under a nitrogen atmosphere. To detoxify impurities that could deactivate the polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger. Then, 20.0 mmol of the polymer block (A) with active terminals obtained above, calculated as the lithium atom content, was added, and the polymerization growth reaction was carried out at 55°C. After the polymerization reaction was continued for 15 minutes, 700 g of 1,3-butadiene was added continuously over 75 minutes. After confirming that the polymerization conversion rate had reached 95% to 100%, 10 minutes later, polyorganosiloxane represented by the above formula (13) was added so that the epoxy group content was 12 mmol, and the reaction was continued for 20 minutes. 20 mmol of 3-(2-aminoethylamino)propyltrimethoxysilane was added, and the reaction was continued for 15 minutes. Then, 2 equivalents of methanol relative to the total amount of lithium in the autoclave were added as a polymerization terminator to obtain a solution containing a conjugated diene polymer. To this solution, 0.20 parts of 2,4-bis(octylthiomethyl)-6-methylphenol were added as an antioxidant per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0226] <Production Example 4> A 20 L autoclave equipped with a stirrer was charged with 9180 g of industrial hexane, 1170 g of cyclohexane, 5.06 mmol of tetramethylethylenediamine, 400 g of 1,3-butadiene, and 560 g of styrene under a nitrogen atmosphere. A small amount of n-butyllithium was added as a scavenger to detoxify impurities that could deactivate the polymerization. Then, 8.03 mmol of the polymer block (A) with active terminals obtained above (calculated as lithium atom content) was added, and the polymerization was allowed to proceed at 45°C. After 20 minutes of polymerization, 544 g of 1,3-butadiene was added over 82 minutes, followed by 96 g of styrene over 60 minutes. After 55 minutes had elapsed since the initiation of chain polymerization, 0.55 mmol of 1,6-bis(trichlorosilyl)hexane was added as a coupling agent. Five minutes after the addition of 1,6-bis(trichlorosilyl)hexane, 1.02 g of bis(diethylamino)methylvinylsilane and 2.90 mmol of the polymer block (A) with active terminals obtained above, calculated as lithium atom content, were added. Ten minutes after the polymerization conversion rate was confirmed to be between 95% and 100%, polyorganosiloxane represented by formula (13) above was added so that the total epoxy group content was 11.45 mmol. The reaction time after each addition was 10 minutes. 25.7 mmol of n-butyllithium was then added and allowed to react for 10 minutes. Then, polyorganosiloxane represented by formula (13) above was added so that the epoxy group content was 8.09 mmol, and allowed to react for 10 minutes. Two equivalents of methanol relative to the total amount of lithium in the autoclave were then added as a polymerization terminator to obtain a solution containing a conjugated diene-based polymer. To this solution, 0.20 parts of 2,4-bis(octylthiomethyl)-6-methylphenol was added as an antioxidant relative to 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0227] <Production Example 5> A 20 L autoclave equipped with a stirrer was charged under a nitrogen atmosphere with 9180 g of industrial hexane, 1170 g of cyclohexane, 5.2 mmol of tetramethylethylenediamine, 500 g of 1,3-butadiene, 800 g of styrene, and 0.43 g of bis(diethylamino)methylvinylsilane. To detoxify impurities that could deactivate the polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger. Then, 20.0 mmol of the polymer block (A) with active terminals obtained above (calculated as lithium atom content) was added, and the polymerization growth reaction was carried out at 55°C. After the polymerization reaction was continued for 15 minutes, 0.86 g of bis(diethylamino)methylvinylsilane was added, followed by the continuous addition of 700 g of 1,3-butadiene over 75 minutes. After confirming that the polymerization conversion rate had reached 95% to 100%, 10 minutes later, polyorganosiloxane represented by the above formula (13) was added so that the epoxy group content was 12 mmol, and the reaction was allowed to proceed for 20 minutes. Two equivalents of methanol were then added to the autoclave as a polymerization terminator, based on the total amount of lithium, to obtain a solution containing a conjugated diene polymer. To this solution, 0.20 parts of 2,4-bis(octylthiomethyl)-6-methylphenol were added as an antioxidant, based on 100 parts of the conjugated diene polymer, to obtain a polymer solution.

[0228] <Production Example 6> A polymer solution was obtained in the same manner as in Production Example 1, except that the polyorganosiloxane represented by the above formula (13) was not added.

[0229] <Production Example 7> A 20 L autoclave equipped with a stirrer was charged under a nitrogen atmosphere with 7650 g of industrial hexane, 2925 g of cyclohexane, 8.81 mL of tetrahydrofuran, 0.88 mL of ethylene glycol dibutyl ether, 248 g of 1,3-butadiene, and 526 g of styrene. A small amount of n-butyllithium was added as a scavenger to detoxify impurities that could deactivate the polymerization. Then, 3.16 mmol of n-butyllithium was added and polymerization was initiated at 43°C. After the polymerization reaction continued for 20 minutes, 680 g of 1,3-butadiene was added over 200 minutes, followed by 93 g of styrene over 55 minutes. After confirming that the polymerization conversion had reached 95% to 100%, 10 minutes later, 0.31 mmol of silicon tetrachloride was added and the reaction was continued for 30 minutes. Then, 1.5 equivalents of methanol were added to the total amount of lithium in the autoclave as a polymerization terminator to obtain a solution containing a conjugated diene polymer. 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilizer GM) and pentaerythrityl tetrakis(3-laurylthiopropionate) (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilizer TP-D) were added to this solution as antioxidants in amounts of 0.40 parts and 0.20 parts, respectively, per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0230] <Production Example 8> A polymer solution was obtained in the same manner as in Production Example 2, except that 1.2 mmol of normal butyllithium and the polyorganosiloxane represented by the above formula (13) were not added.

[0231] <Production Example 9> A polymer solution was obtained in the same manner as in Production Example 5, except that the amount of tetramethylethylenediamine was changed to 5.37 mmol and the polyorganosiloxane represented by the above formula (13) was not added.

[0232] <Production Example 10> A polymer solution was obtained by the same procedure as in Production Example 1, except that 1.83 g of bis(diethylamino)methylvinylsilane was added 15 minutes after the start of polymerization, and 6.41 mmol of [3-(diethylamino)propyl]trimethoxysilane was added instead of the polyorganosiloxane represented by the above formula (13), and the reaction was carried out for 15 minutes.

[0233] [Examples 1 to 8 and Comparative Examples 1 to 4] The polymer solutions and oils obtained in Production Examples 1 to 10 were mixed so that the mass ratio of each conjugated diene polymer to the mass of oil (manufactured by Nippon Oil Corporation, trade name "Aromax T-DAE") contained in each polymer solution was as shown in Table 1. After stirring and mixing until homogeneous, the solvent was removed by steam stripping and the mixture was dried for 24 hours in a vacuum dryer set at 60°C to obtain conjugated diene polymers (A) to (L). The obtained conjugated diene polymers (A) to (L) were measured and evaluated for styrene unit content, vinyl bond content, styrene block ratio, Mooney viscosity, silicon content, ionic strength index, weight-average molecular weight (Mw), molecular weight distribution (Mw / Mn), the number of peaks in the molecular weight distribution curve, and the peak-top molecular weight of each peak. The results are shown in Table 1.

[0234] The conjugated diene polymers (A) to (L) of Examples 1 to 8 and Comparative Examples 1 to 4 were masticated for 30 seconds in a 250 mL Laboplastomill. Subsequently, materials other than sulfur and the vulcanization accelerator were added in the blending ratios (parts by mass) shown in Table 2, followed by further kneading for 3.5 minutes. The rubber composition after primary kneading was then released from the Laboplastomill. The Laboplastomill indicated a temperature of 140°C upon release. The resulting rubber composition after primary kneading was passed twice through an open roll set at a gap width of 1.5 mm and a temperature of 50°C to obtain a rubber composition sheet after primary kneading. The resulting rubber composition sheet after primary kneading was evaluated for processability (sheet gloss) and processability (sheet edge cracking). The results are shown in Table 2.

[0235] Next, the rubber composition sheet after the primary mixing was wrapped around an open roll set at 50°C, and sulfur and a vulcanization accelerator were added and mixed to obtain a sheet-like uncrosslinked rubber composition. The processability (silica dispersion) of the obtained uncrosslinked rubber composition was evaluated. The results are shown in Table 2.

[0236] The uncrosslinked rubber composition obtained above was heated at 160°C for 30 to 35 minutes to crosslink it, thereby obtaining a cross-linked rubber sheet. The cross-linked rubber sheet obtained was evaluated for fuel economy and abrasion resistance. The results are shown in Table 2.

[0237] [Table 1]

[0238] [Table 2]

[0239] The materials shown in Table 2 are as follows: Silica: ULTRASIL (registered trademark) 7000GR, manufactured by EVONIK Oil: Nippon Oil Corporation, product name "Aromax T-DAE" Silane coupling agent: bis(3-(triethoxysilyl)propyl)tetrasulfide (manufactured by Degussa, trade name "Si69") Carbon black: Cabot Japan, product name "N339" Zinc oxide: Zinc oxide type 2, manufactured by Seido Chemical Industry Co., Ltd. Antioxidant: 6PPD, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Nocrac 6C") Stearic acid: NOF Corporation, product name "Beads Stearic Acid Tsubaki" Sulfur: Tsurumi Chemical Co., Ltd., product name "Sulfur 325 mesh" Vulcanization accelerator (1): N-cyclohexyl-2-benzothiazylsulfenamine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccela CZ-G") Vulcanization accelerator (2): Diphenyl guanidine (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Noccela D")

[0240] The following points can be confirmed from Tables 1 and 2. That is, conjugated diene polymers having a silicon content of 95 ppm by weight or more and an ionic strength index of 75% or less were able to give cross-linked rubber products that were excellent in processability, wear resistance, and fuel economy (Examples 1 to 8). On the other hand, when the silicon content was less than 95 ppm by weight or the ionic strength index was more than 75%, the balance between processability, abrasion resistance and fuel economy of the obtained cross-linked rubber was poor (Comparative Examples 1 to 4).

Claims

1. A conjugated diene-based polymer containing conjugated diene monomer units and aromatic vinyl monomer units, The silicon content is 95 ppm by weight or more, an ionic strength index of 75% or less; The weight average molecular weight (Mw) is 500,000 to 10,000,000, The content of aromatic vinyl monomer units is 30% by weight or more and 70% by weight or less, the amount of vinyl bonds in the conjugated diene monomer units is 1 to 50 mol %, A conjugated diene polymer having an aromatic vinyl monomer block ratio of 30.0% or less.

2. 2. The conjugated diene polymer according to claim 1, which has a molecular weight distribution (Mw / Mn) of 1.5 or more.

3. 3. The conjugated diene polymer according to claim 1, wherein the ionic strength index is from 0.5 to 60%.

4. The conjugated diene polymer according to any one of claims 1 to 3, which has two or more peaks in its molecular weight distribution curve.

5. The conjugated diene polymer according to any one of claims 1 to 4, which contains a terminal modified group.

6. A rubber composition comprising the conjugated diene polymer according to any one of claims 1 to 5 and a filler.

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

8. A tire comprising the cross-linked rubber according to claim 7.

9. A method for producing the conjugated diene polymer according to any one of claims 1 to 5, comprising: A method for producing a conjugated diene polymer, comprising a step of mixing two or more conjugated diene polymers in the state of a solution.

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