Conjugated diene polymers, rubber compositions, rubber crosslinks, and tires

Abstract

The present invention provides a conjugated diene polymer which comprises at least a conjugated diene monomer unit, wherein: the molecular weight distribution curve thereof as obtained by GPC measurement has three or more peaks; and with respect to the molecular weight distribution curve, if the peak detected last in the GPC measurement is expressed as the last detected peak (Z), and the peak that has the maximum peak area among the peaks other than the last detected peak (Z) is expressed as the maximum peak (L), the peak top molecular weight of the last detected peak (Z) is from 80,000 to 250,000, and the adsorption ratio of a polymer chain that constitutes the maximum peak (L) with respect to silica is less than 40%.

Description

[Technical Field]

[0001] The present invention relates to a conjugated diene polymer, a rubber composition, a rubber crosslinked product, and a tire, and more particularly to a conjugated diene polymer that can provide a rubber crosslinked product with excellent processability and excellent strength properties, wear resistance properties, and fuel efficiency properties, and to a rubber composition, rubber crosslinked product, and a tire obtained using such a conjugated diene polymer. [Background technology]

[0002] In recent years, with growing concern for environmental issues, polymers used in automobile tires are also required to have excellent fuel efficiency characteristics. Tires obtained using a rubber composition in which silica is compounded as a filler into a conjugated diene polymer exhibit improved low heat generation compared to tires obtained using conventionally used rubber compositions containing carbon black, thus resulting in tires with superior fuel efficiency characteristics.

[0003] As a conjugated diene polymer used to provide such tires, Patent Document 1 discloses a modified conjugated diene polymer that satisfies the following conditions (I) to (IV). (I) The molecular weight distribution curve obtained by gel permeation chromatography (GPC) measurement has at least two peaks. (II) In the molecular weight distribution curve, when the peak with the highest molecular weight is designated as peak (B), and the peak with the largest peak area excluding peak (B) is designated as peak (T), the peak molecular weight of peak (B) is 500,000 to 2,500,000, and the peak molecular weight of peak (T) is 150,000 to 600,000. (III) In the molecular weight distribution curve, when the total area is set to 100%, the area of ​​peak (T) is 30% to 80%, and the sum of the areas of peak (B) and peak (T) is 65% or more. (IV) In the molecular weight distribution curve, the proportion of modified polymer chains included from the low molecular weight side to the point where the area is 5% is between 60% and 99%. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2018 / 056025 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The conjugated diene polymer obtained by the technology described in Patent Document 1 above lacks sufficient processability, and the rubber crosslinked product obtained using it has room for improvement in terms of strength characteristics, wear resistance characteristics, and fuel efficiency characteristics.

[0006] The present invention has been made in view of the above problems, and aims to provide a conjugated diene polymer that can provide a rubber crosslinked product with excellent processability and excellent strength characteristics, wear resistance characteristics, and fuel efficiency characteristics. The present invention also aims to provide a rubber composition, a rubber crosslinked product, and a tire obtained using such a conjugated diene polymer. [Means for solving the problem]

[0007] As a result of diligent research to achieve the above objective, the inventors discovered that the above objective can be achieved by setting the number of peaks in the molecular weight distribution curve to three or more, setting the peak top molecular weight of a specific peak to a specific range, and further setting the adsorption rate of the polymer chain constituting a specific peak to silica to a specific range, thereby completing the present invention.

[0008] In other words, the present invention provides a conjugated diene polymer containing at least conjugated diene monomer units, wherein the number of peaks in the molecular weight distribution curve obtained by gel permeation chromatography is 3 or more, and the peak detected the latest during gel permeation chromatography in the molecular weight distribution curve is defined as the final detection peak (Z), and the peak with the largest peak area among the remaining peaks excluding the final detection peak (Z) is defined as the maximum peak (L), the peak top molecular weight of the final detection peak (Z) is 80,000 to 250,000, and the adsorption rate of the polymer chain constituting the maximum peak (L) to silica is less than 40%.

[0009] In the conjugated diene polymer of the present invention, it is preferable that the peak-top molecular weight of the maximum peak (L) is greater than 600,000. The conjugated diene polymer of the present invention preferably contains terminally modified groups. The conjugated diene polymer of the present invention preferably contains a coupling polymer chain. According to the present invention, a rubber composition containing the above-mentioned conjugated diene polymer and a filler is provided. According to the present invention, a crosslinked rubber product obtained by crosslinking the above-mentioned rubber composition, and a tire containing such a crosslinked rubber product are provided.

[0010] Furthermore, the present invention provides a method for producing the above-mentioned conjugated diene polymer, comprising the step of mixing two or more conjugated diene polymers having different molecular weight distribution curves in a polymer solution state. Furthermore, according to the present invention, a method for producing the above-mentioned conjugated diene polymer is provided, which includes a step of starting the polymerization of a monomer mixture containing a conjugated diene monomer using a polymerization initiator, and then adding a polymerization initiator to the polymerization system to continue polymerization. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a conjugated diene polymer that can provide a rubber crosslinked product with excellent processability and excellent strength characteristics, wear resistance characteristics, and fuel efficiency characteristics. Furthermore, according to the present invention, it is also possible to provide a rubber composition, a rubber crosslinked product, and a tire obtained using such a conjugated diene polymer. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic graph showing the GPC measurement results obtained using styrene-based columns and silica-based columns. [Modes for carrying out the invention]

[0013] <Conjugated diene polymers> The conjugated diene polymer of the present invention is a conjugated diene polymer containing at least conjugated diene monomer units, The molecular weight distribution curve obtained by gel permeation chromatography has three or more peaks. In the molecular weight distribution curve, the peak detected latest during gel permeation chromatography measurement is defined as the final detection peak (Z), and among the remaining peaks excluding the final detection peak (Z), the peak with the largest peak area is defined as the maximum peak (L). The peak top molecular weight of the final detection peak (Z) is between 80,000 and 250,000, and the adsorption rate of the polymer chains constituting the maximum peak (L) to silica is less than 40%.

[0014] The conjugated diene polymer of the present invention contains conjugated diene monomer units. Examples of conjugated diene monomers for forming these 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. In addition, 1,3-butadiene and isoprene may be used in combination.

[0015] In the conjugated diene polymer of the present invention, the lower limit of the content of conjugated diene monomer units is 0% by weight or more. However, from the viewpoint of the wear resistance and low fuel consumption characteristics of the resulting rubber crosslinked product, the content 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, with the total amount of all monomers being 100% by weight. On the other hand, the upper limit of the content of conjugated diene monomer units is 100% by weight or less. However, 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, with the total amount of all monomers being 100% by weight. Furthermore, from the viewpoint of the strength and abrasion resistance properties of the resulting crosslinked rubber product, the preferred lower limit of the content of conjugated diene monomer units, with the total amount of all monomers being 100% by weight, is in order of preference 60% or more, 70% or more, 75% or more, 80% or more, and 85% or more. The preferred upper limit, with the total amount of all monomers being 100% by weight, is in order of preference 98% or less, 96% or less, 94% or less, 92% or less, and 90% or less.

[0016] In the conjugated diene polymer of the present invention, the amount of vinyl bond in the conjugated diene monomer unit is preferably 1 to 90 mol%, more preferably 3 to 80 mol%, even more preferably 5 to 70 mol%, even more preferably 7 to 60 mol%, particularly preferably 9 to 50 mol%, and most preferably 10 to 40 mol%. Furthermore, from the viewpoint of the processability of the conjugated diene polymer, the amount of vinyl bond in the conjugated diene monomer unit may be, for example, 10 to 30 mol%, and from the viewpoint of the strength and abrasion resistance properties of the resulting rubber crosslinked product, it may be, for example, 31 to 40 mol%. By setting the vinyl bond content in the conjugated diene monomer unit within the above range, the low fuel consumption characteristics of the resulting rubber crosslinked product can be further enhanced.

[0017] 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 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 content of aromatic vinyl monomer units in the conjugated diene polymer may be 0% by weight or more, but from the viewpoint of abrasion resistance and low fuel consumption characteristics of the resulting rubber crosslinked product, the content 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, with the total amount of all monomers being 100% by weight. On the other hand, the lower limit of the aromatic vinyl monomer content is 0% by weight or more, but from the viewpoint of the processability of the conjugated diene polymer, the preferred lower limit, with the total amount of all monomers being 100% by weight, is in the following 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. Furthermore, from the viewpoint of the strength properties and abrasion resistance properties of the resulting rubber crosslinked product, the preferred upper limit of the aromatic vinyl monomer content is, with the total amount of all monomers being 100% by weight, in the following order of preference: 40% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, and 15% by weight or less, and the preferred lower limit is, with the total amount of all monomers being 100% by weight, in the following order of preference: 2% by weight or more, 4% by weight or more, 6% by weight or more, 8% by weight or more, and 10% by weight or more.

[0018] When the conjugated diene polymer of the present invention contains aromatic vinyl monomer units, the aromatic vinyl monomer blocking rate 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 blocking rate is measured by 1H-NMR using deuterated chloroform as the solvent. When 6.1 to 7.7 ppm of the obtained 1H-NMR spectrum is taken as the peak derived from aromatic vinyl monomers, and of these, 6.1 to 6.88 ppm is taken as the peak derived from aromatic vinyl monomer blocks, the ratio of the peak area derived from aromatic vinyl monomer blocks to the peak area derived from aromatic vinyl monomers is calculated, and this value is multiplied by 2.5 and expressed as a percentage to obtain the aromatic vinyl monomer blocking rate. When the aromatic vinyl monomer is styrene, it is preferable that the styrene blocking rate is within the above range. By setting the aromatic vinyl monomer blocking rate within the above range, the resulting rubber crosslinked material can be made to have a more highly balanced abrasion resistance and low fuel consumption characteristics.

[0019] The aromatic vinyl monomer blocking rate can be controlled by adjusting the timing of the addition of conjugated diene monomers and aromatic vinyl monomers to the polymerization system. Conjugated diene monomers and aromatic vinyl monomers can be added to the polymerization system at any time, regardless of whether the polymerization initiator has been added or not.

[0020] Furthermore, the conjugated diene polymer of the present invention may contain, in addition to conjugated diene monomer units and optionally aromatic vinyl monomer units, units of vinyl compounds containing functional groups capable of interacting with silica.

[0021] The vinyl compound containing a functional group that can interact with silica, used to form a unit of a vinyl compound containing a functional group that can interact with silica, is not particularly limited to any compound containing a functional group that can interact with silica and a vinyl group. Here, a functional group that can interact with silica is a functional group that can form a covalent bond between the functional group and the silica surface, or form an intermolecular force weaker than a covalent bond (e.g., ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.). Such a functional group that can interact with silica is not particularly limited, but examples include nitrogen atom-containing functional groups, silicon atom-containing functional groups, and oxygen atom-containing functional groups, and among these, silicon atom-containing functional groups are preferred from the viewpoint of high interaction with silica.

[0022] As a preferred embodiment of a vinyl compound containing a functional group that can interact with silica, for example, a compound represented by the following general formula (1) can be suitably used as a vinyl compound containing a silicon atom-containing functional group. [ka] In the above general formula (1), X 1 X represents a chemical single bond or a hydrocarbylene group. 2 , X 3 and X 4 Each of these independently represents a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have substituents.

[0023] In the above general formula (1), X 1 This is a chemical single bond or a hydrocarbylene group, preferably a chemical single bond. Examples of hydrocarbylene groups include alkylene groups, alkenediyl groups, arylene groups, or groups formed by the bonding of an arylene group and an alkylene group. Examples of the alkylene group include a methylene group, an ethylene group, a trimethylene group, etc. Examples of the alkenediyl group include a vinylene group, an ethylene-1,1-diyl group, etc. Examples of the arylene group include a phenylene group, a naphthylene group, a biphenylene group, etc. Examples of the group formed by bonding of an arylene group and an alkylene group include a group formed by bonding of a phenylene group and a methylene group, a group formed by bonding of a phenylene group and an ethylene group, etc. X 1 When X 1 is a hydrocarbylene group, X

[0024] In the above general formula (1), X 2 , X 3 and X 4 each independently represent a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent. Among X 2 , X 3 and X 4 , at least one is preferably a substituted amino group, and among X 2 , X 3 and X 4 , more preferably two are substituted amino groups.

[0025] X 2 , X 3 and X 4 The substituted amino group that can constitute is preferably a group represented by the following general formula (2). R 1 -N(-R 2 )- (2) In the above general formula (2), R 1 and R 2 may be bonded to each other or may not be bonded. When R 1 and R 2 are not bonded to each other, R 1 and R 2 each independently represent a hydrocarbyl group which may have a substituent or a trihydrocarbylsilyl group. When R​​​When R is connected to each other, 1 and R 2 This represents a hydrocarbylene group which may contain at least one atom selected from nitrogen, oxygen, sulfur, and silicon.

[0026] R 1 and R 2 Examples of hydrocarbyl groups that can constitute a hydrocarbyl group include linear alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, and n-octyl groups; cyclic alkyl groups such as cyclopentyl and cyclohexyl groups; and aryl groups such as phenyl, benzyl, and naphthyl groups. Among these, linear alkyl groups are preferred, and methyl or ethyl groups are more preferred. R 1 and R 2 If the hydrocarbyl group that can constitute the group has substituents, examples include hydrocarbyl groups having a hydrocarbyloxy group as a substituent. Examples of hydrocarbyl groups having a hydrocarbyloxy group as a substituent include alkoxyalkyl groups such as methoxymethyl, ethoxymethyl, and methoxyethyl groups; and aryloxyalkyl groups such as phenoxymethyl groups.

[0027] R 1 and R 2 Specific examples of trihydrocarbyl silyl groups that can constitute this include trimethylsilyl groups, triethylsilyl groups, and trialkylsilyl groups such as tert-butyldimethylsilyl groups.

[0028] R 1 and R 2 When R is connected to each other, 1 and R 2Examples of hydrocarbylene groups 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 pentane-2-ene-1,5-diyl. 1 and R 2 If the hydrocarbylene group that can constitute the group contains at least one selected from nitrogen, oxygen, sulfur, and silicon atoms, examples of hydrocarbylene groups containing at least one selected from nitrogen, oxygen, sulfur, and silicon atoms include groups represented by -CH=N-CH=CH-, groups represented by -CH=N-CH2-CH2-, groups represented by -CH2-CH2-O-CH2-CH2-, groups represented by -CH2-CH2-S-CH2-CH2-, groups represented by -CH2-CH2-SiH2-CH2-CH2-, groups represented by -CH2-CH2-SiMe2-CH2-CH2-, and groups represented by -CH2-CH2-SiEt2-CH2-CH2-. R 1 and R 2 is either an alkyl group or R 1 and R 2 It is preferable that these groups are bonded to each other to form an alkylene group, R 1 and R 2 It is more preferably an alkyl group, R 1 and R 2 It is more preferable that the group is a methyl group or an ethyl group.

[0029] 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; and the like. Among these, dialkylamino groups are preferred, and dimethylamino group, diethylamino group, and di-n-butylamino group are more preferred.

[0030] In the above general formula (2), R 1 and R 2 However, in the case of a hydrocarbyl group having a hydrocarbyloxy group as a substituent, specific examples of the group represented by the above general formula (2) include di(methoxymethyl)amino groups, di(ethoxymethyl)amino groups, and other di(alkoxyalkyl)amino groups.

[0031] In the above general formula (2), R 1 and R 2 However, in the case of a trihydrocarbyl silyl group, specific examples of the group represented by the above general formula (2) include bis(trimethylsilyl)amino group, bis(tert-butyldimethylsilyl)amino group, N-trimethylsilyl-N-methylamino group, and other trialkylsilyl group-containing amino groups.

[0032] In the above general formula (2), R 1 and R 2 Specific examples of the group represented by the general formula (2) above, when the two groups are bonded to each other to form a hydrocarbylene group, include 1-trimethyleneimino group, 1-pyrrolidino group, 1-piperidino group, 1-hexamethyleneimino group, 1-heptamethyleneimino group, 1-octamethyleneimino group, 1-decamethyleneimino group, 1-dodecamethyleneimino group, and other 1-alkyleneimino groups.

[0033] In the above general formula (2), R 1 and R 2When these groups 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 the 1-imidazolyl group, the 4,5-dihydro-1-imidazolyl group, and the morpholino group.

[0034] The group represented by the above general formula (2) is preferably a dialkylamino group or a 1-alkyleneimino group, more preferably a dialkylamino group, and even more preferably a dimethylamino group, a diethylamino group, or a di-n-butylamino group.

[0035] In the above general formula (1), X 2 , X 3 and X 4 Examples of hydrocarbyloxy groups that can constitute a hydrocarbyloxy group include alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, and tert-butoxy groups; and aryloxy groups such as phenoxy and benzyloxy groups.

[0036] In the above general formula (1), X 2 , X 3 and X 4 Examples of hydrocarbyl groups that can constitute this include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl groups; and aryl groups such as phenyl, 4-methyl-1-phenyl, and benzyl groups. X 2 , X 3 and X 4 If the hydrocarbyl group that can constitute the compound has substituents, examples include hydrocarbyl groups having a hydrocarbyloxy group as substituents, and alkoxyalkyl groups such as methoxymethyl, ethoxymethyl, and ethoxyethyl groups.

[0037] In the above general formula (1), X 1 This is a chemical single bond, X 2 , X 3 and X 4Specific examples of vinyl compounds containing a silicon atom-containing functional group represented by the above general formula (1), in which one of the groups is a substituted amino group, include (dimethylamino)dimethylvinylsilane, (ethylmethylamino)dimethylvinylsilane, (di-n-propylamino)dimethylvinylsilane, (diisopropylamino)dimethylvinylsilane, (dimethylamino)diethylvinylsilane, (ethylmethylamino)diethylvinylsilane, (di-n-propylamino)diethylvinylsilane, (diisopropylamino)diethylvinylsilane, and other (dialkylamino)dialkylvinylsilanes; [bis(trimethylsilyl)amino]dimethylvinylsilane, [bis(t-butyldimethylsilyl)amino]dimethylvinylsilane, [bis(trimethylsilyl)amino]diethylvinylsilane, and other [bis(t-butyldimethylsilyl)amino]diethylvinylsilane, and other [bis(t-butyldimethylsilyl)amino]diethylvinylsilane, and other [bis(t-butyldimethylsilyl)amino]diethylvinylsilane, and other [bis(t-butyldimethylsilyl)amino]diethylvinylsilane, and other [bis(t-) Examples include (trialkylsilyl)amino]dialkylvinylsilanes; (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, (diethylamino)di(ethoxyethyl)vinylsilane, (diethylamino)di(ethoxyethyl)vinylsilane, and other (dialkylamino)di(alkoxyalkyl)vinylsilanes; and cyclic aminodialkylvinylsilane compounds such as pyrrolidinodimethylvinylsilane, piperidinodimethylvinylsilane, hexamethyleneiminodimethylvinylsilane, 4,5-dihydroimidazolyldimethylvinylsilane, and morpholinodimethylvinylsilane.

[0038] In the above general formula (1), X 1 is a hydrocarbylene group, 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), where 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, and (di-n-butylamino)dimeth Examples include (dialkylamino)dialkylvinylphenylsilanes such as (di-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.

[0039] In the above general formula (1), X 1 This is a chemical single bond, 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)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, bis(di-n-butylamino)ethylvinylsilane, and other bis(dialkylamino)alkylvinylsilanes; bis[bis(trimethylsilyl)amino]methylvinylsilane, bis[bis(tert-butyldimethylsilyl)amino]methylvinylsilane, bis[bis(trimethylsilyl)amino]ethylvinylsilane, and bis[bis(tert-butyldimethylsilyl)amino]ethylvinylsilane. Examples include bis[bis(trialkylsilyl)amino]alkylvinylsilanes; bis(dimethylamino)methoxymethylvinylsilane, bis(dimethylamino)methoxyethylvinylsilane, bis(dimethylamino)ethoxymethylvinylsilane, bis(dimethylamino)ethoxyethylvinylsilane, bis(dimethylamino)methoxymethylvinylsilane, bis(diethylamino)methoxyethylvinylsilane, bis(diethylamino)ethoxymethylvinylsilane, bis(dimethylamino)ethoxyethylvinylsilane, bis(dimethylamino)ethoxyethylvinylsilane, and other bis(dialkylamino)alkoxyalkylsilanes; bis(pyrrolidino)methylvinylsilane, bis(piperidino)methylvinylsilane, bis(hexamethyleneimino)methylvinylsilane, bis(4,5-dihydroimidazolyl)methylvinylsilane, bis(morpholino)methylvinylsilane, and other bis(cyclicamino)alkylvinylsilane compounds; and so on.

[0040] In the above general formula (1), X 1 is a hydrocarbylene group, X 2 , X 3 and X 4Among them, when two of them are substituted amino groups, specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the above general formula (1) 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-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, bis(di-n-butylamino)ethyl-3-vinylphenylsilane, and bis(dialkylamino)alkylvinylphenylsilanes such as these.

[0041] In the above general formula (1), X 1 is a chemical single bond, and among X 2 , X 3 and X 4 When three of them are substituted amino groups, specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the above general formula (1) include tris(dialkylamino)vinylsilanes such as tris(dimethylamino)vinylsilane, tris(diethylamino)vinylsilane, tris(di-n-propylamino)vinylsilane, tris(di-n-butylamino)vinylsilane.

[0042] In the above general formula (1), X 1 is a hydrocarbylene group, and X 2 , X 3 and X 4Among them, when three of them are substituted amino groups, specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the above general formula (1) include 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, tris(di-n-butylamino)-3-vinylphenylsilane, and tris(dialkylamino)vinylphenylsilanes such as those mentioned above.

[0043] In the above general formula (1), X 1 is a chemical single bond, and among X 2 , X 3 and X 4 when none of them is a substituted amino group, specific examples of the vinyl compound containing a silicon atom-containing functional group represented by the above general formula (1) include trialkoxyvinylsilanes such as trimethoxyvinylsilane, triethoxyvinylsilane, tripropoxyvinylsilane; dialkoxyalkylvinylsilanes such as methyldimethoxyvinylsilane, methyldiethoxyvinylsilane; dialkoxyarylvinylsilanes such as di(tert-pentoxy)phenylvinylsilane, di(tert-butoxy)phenylvinylsilane; monoalkoxydialkylvinylsilanes such as dimethylmethoxyvinylsilane; monoalkoxydiarylvinylsilanes such as tert-butoxydiphenylvinylsilane, tert-pentoxydiphenylvinylsilane; monoalkoxyalkylarylvinylsilanes such as tert-butoxymethylphenylvinylsilane, tert-butoxyethylphenylvinylsilane; substituted alkoxyvinylsilane compounds such as tris(β-methoxyethoxy)vinylsilane; and the like.

[0044] Among the compounds represented by the above general formula (1), those in which X 1 is a chemical single bond are preferred, and X1 is a chemical single bond, and X 2 , X 3 and X 4 Of these, compounds in which two are substituted amino groups are more preferred, X 1 is a chemical single bond, and X 2 , X 3 and X 4 Of these, compounds in which two are dialkylamino groups are particularly preferred.

[0045] Among the compounds represented by the above general formula (1), bis(dimethylamino)methylvinylsilane, bis(diethylamino)methylvinylsilane, and bis(di-n-butylamino)methylvinylsilane are preferred, and bis(diethylamino)methylvinylsilane is particularly preferred.

[0046] In addition, vinyl compounds containing functional groups that can interact 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.

[0047] Furthermore, when a 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) will be introduced into the conjugated diene polymer of the present invention as the unit of the vinyl compound containing a functional group capable of interacting with silica. [ka] In the above general formula (3), X 5 X represents a chemical single bond or a hydrocarbylene group. 6 , X 7 and X8 Each of these independently represents a hydroxyl group, a substituted amino group, a hydrocarbyloxy group, or a hydrocarbyl group which may have a substituent.

[0048] Furthermore, in the unit represented by the general formula (3) above, X 5 X in the compound represented by the general formula (1) above. 1 Corresponding to the unit represented by the general formula (3) above, X 6 , X 7 and X 8 X in the compound represented by the general formula (1) above. 2 , X 3 and X 4 This corresponds to each of the above general formulas (3). Therefore, in the unit represented by the above general formula (3), X 5 , X 6 , X 7 and X 8 X in the compound represented by the general formula (1) above. 1 , X 2 , X 3 and X 4 These can be considered the same as the above. Also, as a compound represented by the above general formula (1), X 2 , X 3 and X 4 If at least one of them is a substituted amino group or a hydrocarbyloxy group, the substituted amino group or hydrocarbyloxy group is hydrolyzed at any step and timing, resulting in X 2 , X 3 and X 4 At least one of these can be a hydroxyl group.

[0049] In the conjugated diene polymer of the present invention, the content of units of the vinyl compound containing a functional group that can interact 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. By setting the content of units of the vinyl compound containing a functional group that can interact with silica within the above range, the processability of the conjugated diene polymer, the strength properties, wear resistance properties, and low fuel consumption properties of the resulting rubber crosslinked product can be improved in a well-balanced manner.

[0050] Furthermore, the conjugated diene polymer of the present invention may contain conjugated diene monomer units and, if necessary, aromatic vinyl monomer units and other monomer units other than those of vinyl compounds containing functional groups that can interact with silica. Examples of other compounds constituting such other monomer units include chain 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.

[0051] In the conjugated diene polymer of the present invention, the bonding mode of each monomer unit can be various, such as block-like, tapered, or random, but a random bonding mode is preferred. By using a random bonding mode, the low fuel consumption characteristics of the resulting rubber crosslinked product can be further enhanced.

[0052] Furthermore, the conjugated diene polymer of the present invention is preferably one that contains a modifying group, and more preferably one that contains a modifying group (terminal modified group) formed by modifying the ends of the polymer chains of the conjugated diene polymer with a modifying agent. In this specification, "conjugated diene polymer containing a modifying group" means that 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.

[0053] As a modifying group, it is preferable to use one that contains a functional group that can interact with silica, from the viewpoint of appropriately increasing the affinity to fillers such as silica and further improving the strength properties, wear resistance properties, and fuel efficiency properties of the resulting rubber crosslinked product. Here, a functional group that can interact with silica is a functional group that can form a covalent bond between the functional group and the silica surface, or form an intermolecular force weaker than a covalent bond (for example, ion-dipole interaction, dipole-dipole interaction, hydrogen bond, van der Waals force, etc.). Such a functional group that can interact with silica is not particularly limited, but examples include nitrogen atom-containing functional groups, silicon atom-containing functional groups, and oxygen atom-containing functional groups.

[0054] As a modifying agent for forming a modifying group, silicon atom-containing modifying agents having a silicon atom-containing functional group and nitrogen atom-containing modifying agents having a nitrogen atom-containing functional group are preferred from the viewpoint of high interaction with silica, and silicon atom-containing modifying agents are more preferred. Examples of silicon atom-containing modifying agents include siloxane compounds and hydrocarbyloxysilane compounds. Examples of nitrogen atom-containing modifying agents include N,N-disubstituted aminoalkyl (meth)acrylamide such as dimethylaminoethylacrylamide, diethylaminoethylacrylamide, dimethylaminopropylacrylamide, diethylaminopropylacrylamide, dimethylaminobutylacrylamide, diethylaminobutylacrylamide, dimethylaminoethylmethacrylamide, diethylaminoethylmethacrylamide, dimethylaminopropylmethacrylamide, diethylaminopropylmethacrylamide, dimethylaminobutylmethacrylamide, and diethylaminobutylmethacrylamide. Examples include mids; 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.

[0055] The siloxane compound can be any compound having a siloxane structure (-Si-O-) as its main chain structure, and is not particularly limited, but organosiloxanes having organic groups in the side chains are preferred, and polyorganosiloxanes represented by the following general formula (4) are more preferred. [ka]

[0056] In the above general formula (4), R 3 ~R10 This is an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and these may be the same or different from each other. 9 and X 12 This group is selected from the group consisting of C1-C6 alkyl groups, C6-C12 aryl groups, C1-C5 alkoxy groups, and C4-C12 groups, and these groups may be the same or different from each other. 10 X is a group having 4 to 12 carbon atoms that contains an alkoxy group having 1 to 5 carbon atoms, or an epoxy group. 10 When there are multiple instances, they may be identical or different from one another. 11 This is a group containing 2 to 20 repeating units of alkylene glycol, X 11 When there are multiple values, they may be identical or different from one another. m is an integer between 0 and 200, n is an integer between 0 and 200, k is an integer between 0 and 200, and m+n+k is 1 or greater.

[0057] In the polyorganosiloxane represented by the above general formula (4), R in the above general formula (4) 3 ~R 10 , X 9 and X 12 Examples of C1-C6 alkyl groups that can constitute the polyorganosiloxane include methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, hexyl, and cyclohexyl groups. Examples of C6-C12 aryl groups include phenyl and methylphenyl groups. Among these, methyl and ethyl groups are preferred from the viewpoint of ease of production of the polyorganosiloxane itself.

[0058] Furthermore, in the polyorganosiloxane represented by the above general formula (4), X 9 , X 10 and X 12Examples of alkoxy groups having 1 to 5 carbon atoms that can constitute the polyorganosiloxane include methoxy, ethoxy, propoxy, isopropoxy, and butoxy groups. Among these, methoxy and ethoxy groups are preferred from the viewpoint of ease of production of the polyorganosiloxane itself.

[0059] Furthermore, in the polyorganosiloxane represented by the above general formula (4), X 9 , X 10 and X 12 Examples of groups containing epoxy groups with 4 to 12 carbon atoms that can constitute this include the group represented by the following general formula (5). -Z 1 -Z 2 -E 1 (5) In the above general formula (5), Z 1 This 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 It is a hydrocarbon group having 2 to 10 carbon atoms and containing an epoxy group.

[0060] The base represented by the above general formula (5) is Z 2 Preferably, Z is an oxygen atom. 2 is an oxygen atom, and E 1 It is more preferable that the group is a glycidyl group, Z 1 This is an alkylene group with 1 to 3 carbon atoms, Z 2 is an oxygen atom, and E 1 It is particularly preferable that the group is a glycidyl group.

[0061] Furthermore, in the polyorganosiloxane represented by the above general formula (4), X 9 and X 12 Among the above, groups with 4 to 12 carbon atoms containing an epoxy group, or alkyl groups with 1 to 6 carbon atoms are preferred. Also, X 10 Among the above, groups containing epoxy groups with 4 to 12 carbon atoms are preferred. Furthermore, X 9 and X 12X is an alkyl group having 1 to 6 carbon atoms, 10 It is more preferable that the group is a carbon-4 to carbon-12 group containing an epoxy group.

[0062] Furthermore, in the polyorganosiloxane represented by the above general formula (4), X 11 As a group containing 2 to 20 repeating units of alkylene glycol, a group represented by the following general formula (6) is preferred. [ka] In the above general formula (6), a is an integer between 2 and 20, and X 13 R is an alkylene group or alkylarylene group having 2 to 10 carbon atoms, 11 X is a hydrogen atom or a methyl group, 14 is an alkoxy group or aryloxy group having 1 to 10 carbon atoms. Among these, a is an integer from 2 to 8, and X 13 This is an alkylene group with 3 carbon atoms, and R 11 is a hydrogen atom, and X 14 It is preferable that the group is a methoxy group.

[0063] In the polyorganosiloxane represented by the general formula (4) above, m is an integer from 0 to 200, preferably an integer from 20 to 150, and more preferably an integer from 30 to 120. When m is 200 or less, the production of the polyorganosiloxane represented by the general formula (4) becomes easier, and its viscosity does not become too high, making it easier to handle.

[0064] Furthermore, in the polyorganosiloxane represented by the general formula (4) above, n is an integer from 0 to 200, preferably an integer from 0 to 150, more preferably an integer from 0 to 120. k is an integer from 0 to 200, preferably an integer from 0 to 150, more preferably an integer from 0 to 130. The sum 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 sum of m, n, and k is 1 or more, the reaction between the polyorganosiloxane represented by the general formula (4) above and the active end of the conjugated diene polymer proceeds easily in the manufacturing process of the conjugated diene polymer. Furthermore, when the sum of m, n, and k is 400 or less, the manufacturing of the polyorganosiloxane represented by the general formula (4) above becomes easier, and its viscosity does not become too high, making it easy to handle.

[0065] A hydrocarbyloxysilane compound is a silicon-containing compound having at least one hydrocarbyloxy group. Preferably, the hydrocarbyloxysilane compound has at least one group containing a nitrogen atom in addition to the hydrocarbyloxy group, and more preferably, such a 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. While there are no particular limitations on such a hydrocarbyloxysilane compound, compounds represented by the following general formula (7) can be suitably used.

[0066] [ka] In the above general formula (7), R 12 is a hydrocarbyl group, and A 1 This is a hydrocarbyloxy group, and A 2 This is a group containing a nitrogen atom, where p is an integer from 0 to 2, q is an integer from 1 to 3, r is an integer from 1 to 3, and p + q + r = 4.

[0067] Specific examples of compounds represented by the above general formula (7) are not particularly limited, but for example, A in general formula (7)2 However, as a compound containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom, A is a compound such as 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropylmethyldiethoxysilane, and 3-aminopropyltriethoxysilane. 2 Examples include compounds having a 3-aminopropyl group; such as 4-aminobutyldimethylmethoxysilane, 4-aminobutylmethyldimethoxysilane, 4-aminobutyltrimethoxysilane, 4-aminobutyldimethylethoxysilane, 4-aminobutylmethyldiethoxysilane, and 4-aminobutyltriethoxysilane. 2 Examples include compounds having a 4-aminobutyl group; such as 3-(2-aminoethylamino)propyldimethylmethoxysilane, 3-(2-aminoethylamino)propylmethyldimethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-(2-aminoethylamino)propyldimethylethoxysilane, 3-(2-aminoethylamino)propylmethyldiethoxysilane, and 3-(2-aminoethylamino)propyltriethoxysilane. 2 Examples include compounds having a 3-(2-aminoethylamino)propyl group; and among these, A 2 Compounds having a 3-(2-aminoethylamino)propyl group are preferred, and 3-(2-aminoethylamino)propyltrimethoxysilane is more preferred.

[0068] Also, A in general formula (7) 2 However, as a compound whose group is 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, A is a compound such as 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-dimethylaminopropyldimethylmethoxysilane, 3-dimethylaminopropyltriethoxysilane, 3-dimethylaminopropylmethyldiethoxysilane, and 3-dimethylaminopropyldimethylethoxysilane. 2Examples include compounds having a 3-dimethylaminopropyl group; such as [3-(diethylamino)propyl]trimethoxysilane, 3-diethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyldimethylmethoxysilane, 3-diethylaminopropyltriethoxysilane, 3-diethylaminopropylmethyldiethoxysilane, and 3-diethylaminopropyldimethylethoxysilane. 2 Examples include compounds having a 3-diethylaminopropyl group; such as 3-dipropylaminopropyltrimethoxysilane, 3-dipropylaminopropylmethyldimethoxysilane, 3-dipropylaminopropyldimethylmethoxysilane, 3-dipropylaminopropyltriethoxysilane, 3-dipropylaminopropylmethyldiethoxysilane, and 3-dipropylaminopropyldimethylethoxysilane. 2 Examples include compounds having a 3-dipropylaminopropyl group; such as 3-dibutylaminopropyltrimethoxysilane, 3-dibutylaminopropylmethyldimethoxysilane, 3-dibutylaminopropyldimethylmethoxysilane, 3-dibutylaminopropyltriethoxysilane, 3-dibutylaminopropylmethyldiethoxysilane, and 3-dibutylaminopropyldimethylethoxysilane. 2 Examples include compounds having a 3-dibutylaminopropyl group; such as 3-phenylmethylaminopropyltrimethoxysilane, 3-phenylmethylaminopropylmethyldimethoxysilane, 3-phenylmethylaminopropyldimethylmethoxysilane, 3-phenylmethylaminopropyltriethoxysilane, 3-phenylmethylaminopropylmethyldiethoxysilane, and 3-phenylmethylaminopropyldimethylethoxysilane. 2 Examples include compounds having a 3-phenylmethylaminopropyl group; such as 3-(4-methylpiperazinyl)propyltrimethoxysilane, 3-(4-methylpiperazinyl)propylmethyldimethoxysilane, 3-(4-methylpiperazinyl)propyldimethylmethoxysilane, 3-(4-methylpiperazinyl)propyltriethoxysilane, 3-(4-methylpiperazinyl)propylmethyldiethoxysilane, and 3-(4-methylpiperazinyl)propyldimethylethoxysilane.2 Examples include compounds having a 3-(4-methylpiperazinyl)propyl group;

[0069] A 2 Examples include compounds having an N,N-bis(trimethylsilyl)aminopropyl group; such as N,N-bis(triethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(triethylsilyl)aminopropylmethyldimethoxysilane, and N,N-bis(triethylsilyl)aminopropylmethyldiethoxysilane. 2 Examples include compounds having an N,N-bis(triethylsilyl)aminopropyl group; such as 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 include compounds having an N,N',N'-tris(trimethylsilyl)-N-(2-aminoethyl)-3-aminopropyl group; and among these, A 2 Compounds having a 3-dimethylaminopropyl group are preferred, and 3-dimethylaminopropyltrimethoxysilane is more preferred.

[0070] Furthermore, as the hydrocarbyloxysilane compound, compounds represented by the following general formula (8) can also be suitably used. [ka] In the above general formula (8), A 3 is a hydrocarbyl oxy group, R 13 R represents a hydrocarbon group which may have substituents, 14 and R 15 Each of these independently represents a hydrocarbon group which may have substituents, and R 14 and R 15 These atoms may bond to each other, forming a ring structure with the nitrogen atom to which they bond. In the case of forming such a ring structure, they may also form the ring structure with heteroatoms other than the nitrogen atom to which they bond. s is an integer between 0 and 2.

[0071] Among the compounds represented by the above general formula (8), R is particularly preferred. 14 and R 15 Examples include compounds in which hydrocarbon groups represented by are bonded to each other, forming a piperazine ring structure together with the nitrogen atoms 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 represented by general formula (8), the fuel efficiency characteristics of the resulting rubber crosslinked product can be further improved. [ka] In the above general formula (9), A 3 , R 13 , and s all represent the same things as in the general formula (8) above, R 16 This represents a hydrocarbon group.

[0072] Specific examples of compounds represented by the above 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, and 2-methoxy-2-methyl-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane. These compounds represented by general formula (8) may be used individually or in combination of two or more.

[0073] Among hydrocarbyloxysilane compounds, the compound represented by the above general formula (7) is preferred because it can further improve the processability of the conjugated diene polymer, the wear resistance and low fuel consumption characteristics of the resulting rubber crosslinked product in a well-balanced manner, and A in the above general formula (7) 2 However, compounds containing a primary amino group having an active hydrogen atom and / or a secondary amino group having an active hydrogen atom are more preferred, and A in the above general formula (7) 2 However, compounds containing both a primary amino group having an active hydrogen atom and a secondary amino group having an active hydrogen atom are even more preferred.

[0074] In the conjugated diene polymer of the present invention, the number of peaks in the molecular weight distribution curve obtained by gel permeation chromatography (hereinafter sometimes referred to as GPC) is 3 or more. In the conjugated diene polymer of the present invention, having 3 or more peaks in the molecular weight distribution curve allows the molecular weight distribution to spread appropriately, making it easier for the polymer chains of the conjugated diene polymer to entangle, and as a result, the effects of the present invention can be obtained.

[0075] The number of peaks in the molecular weight distribution curve should be three or more, and is not particularly limited, but is more preferably in the range of 3 to 6, and even more preferably in the range of 4 to 5. By having the number of peaks in the molecular weight distribution curve within the above range, the processability of the conjugated diene polymer, the strength properties, wear resistance properties, and low fuel consumption properties of the resulting rubber crosslinked product can be improved in a well-balanced manner.

[0076] The number of peaks in the molecular weight distribution curve can be determined by the following procedure. Specifically, a sample solution containing a conjugated diene polymer and an internal standard polystyrene with a molecular weight of 5000 is subjected to GPC measurement using a styrene column. From the obtained molecular weight distribution curve, the region with a molecular weight of less than 5000 is removed, and further, the peak of the internal standard polystyrene is removed to obtain the molecular weight distribution curve of the conjugated diene polymer. The obtained molecular weight distribution curve of the conjugated diene polymer is then divided into regions that are sandwiched between the baseline or minimum value and have one maximum value. The peak area of ​​each divided region is determined, and the number of regions with a peak area of ​​1% or more when the total peak area of ​​the molecular weight distribution curve of the conjugated diene polymer is set to 100% can be determined as the number of molecular weight peaks. The specific measurement conditions can be those described in the examples below.

[0077] Methods for obtaining three or more peaks in the molecular weight distribution curve include, for example, blending two or more conjugated diene polymers having different molecular weight distribution curves, adding a polymerization initiator during polymerization when synthesizing a conjugated diene polymer by polymerizing a monomer mixture, or performing a coupling reaction on the polymer chains obtained by polymerization. These methods may be used in combination. Furthermore, during polymerization, the number of peaks in the molecular weight distribution curve, the peak top molecular weight of each peak such as the final detection peak (Z) and maximum peak (L) described later, and the content ratio of polymer chains constituting each peak can be controlled by selecting, for example, the timing and amount of polymerization initiator to be added, the timing of the coupling reaction, and the type of coupling agent used.

[0078] In the conjugated diene polymer of the present invention, the peak-top molecular weight of the final detection peak (Z) is 80,000 to 250,000. Here, the final detection peak (Z) is the peak detected latest during GPC measurement in the molecular weight distribution curve obtained by GPC measurement, and corresponds to the peak in the region with the lowest molecular weight in the molecular weight distribution curve (i.e., the first peak described later). The peak-top molecular weight is the molecular weight at which the peak shows its maximum value. The peak-top molecular weight of the final detection peak (Z) can be determined based on the molecular weight distribution curve obtained by measuring the number of peaks in the molecular weight distribution curve described above.

[0079] In the conjugated diene polymer of the present invention, when the peak top molecular weight of the final detected peak (Z) is between 80,000 and 250,000, the polymer chains of the conjugated diene polymer are well intertwined, and as a result, the effects of the present invention can be obtained. The peak top molecular weight of the final detected peak (Z) is not particularly limited, but is preferably in the range of 100,000 to 250,000, more preferably in the range of 130,000 to 220,000, and even more preferably in the range of 150,000 to 210,000. When the peak top molecular weight of the final detected peak (Z) is within the above range, the processability of the conjugated diene polymer, the strength properties, wear resistance properties, and low fuel consumption properties of the resulting rubber crosslinked product can be improved in a well-balanced manner.

[0080] Methods for controlling the peak-top molecular weight of the final detection peak (Z) are not particularly limited, but include adjusting the amount of polymerization initiator used when obtaining a conjugated diene polymer by polymerization, and adjusting the time for which polymerization continues after adding the polymerization initiator to the polymerization system.

[0081] In the conjugated diene polymer of the present invention, the content of polymer chains constituting the final detection peak (Z) is not particularly limited, but is preferably 1 to 90% by weight, more preferably 3 to 70% by weight, even more preferably 4 to 60% by weight, especially preferably 5 to 50% by weight, particularly preferably 5 to 40% by weight, and most preferably 6 to 30% by weight, relative to the total weight of the conjugated diene polymer. By having the content of polymer chains constituting the final detection peak (Z) within the above range, the processability of the conjugated diene polymer, the strength properties, wear resistance properties, and low fuel consumption properties of the resulting rubber crosslinked product can be improved in a well-balanced manner.

[0082] The polymer chain constituting the final detection peak (Z) preferably contains units of a vinyl compound containing a functional group that can interact with silica, more preferably contains units of a vinyl compound containing a silicon atom-containing functional group, and even more preferably contains units of a compound represented by general formula (1) (i.e., units represented by general formula (3)). By containing such monomer units in the polymer chain constituting the final detection peak (Z), the processability of the conjugated diene polymer, the strength properties, wear resistance properties, and low fuel consumption properties of the resulting rubber crosslinked product can be further enhanced in a balanced manner. The content of units of a vinyl compound containing a functional group that can interact with silica in the polymer chain constituting the final detection peak (Z) is preferably 0.001 to 10.000% by weight, more preferably 0.001 to 3.00% by weight, and even more preferably 0.002 to 1.00% by weight. The content ratio of the polymer chain constituting the final detection peak (Z) can be determined from the ratio of the peak area of ​​the final detection peak (Z) to the peak area of ​​the molecular weight distribution curve of the conjugated diene polymer.

[0083] In the conjugated diene polymer of the present invention, the adsorption rate of the polymer chain constituting the maximum peak (L) to silica is less than 40%. Here, the maximum peak (L) is the peak with the largest peak area among the remaining peaks in the molecular weight distribution curve obtained by GPC measurement, excluding the final detection peak (Z). The molecular weight range representing the polymer chain constituting the maximum peak (L) can be determined based on the molecular weight distribution curve obtained by measuring the number of peaks in the molecular weight distribution curve described above.

[0084] In the present invention, the adsorption rate of the polymer chain constituting the maximum peak (L) to silica can be determined, for example, by performing GPC measurements using a styrene-based column and a silica-based column for a conjugated diene polymer, and based on these results, according to the following formula (I). Specific measurement conditions can be those described in the examples below. Adsorption rate (%) of the polymer chain constituting the maximum peak (L) to silica = [1 - (P2 × P3) / (P1 × P4)] × 100 (I) P1: Peak area of ​​the polymer chain constituting the maximum peak (L), as measured by GPC using a styrene-based column. P2: Peak area of ​​the internal standard polystyrene peak measured by GPC using a styrene-based column. P3: Peak area of ​​the polymer chain peak constituting the maximum peak (L), as determined by GPC measurement using a silica column. P4: Peak area of ​​the internal standard polystyrene peak measured by GPC using a silica column. Furthermore, columns using styrene-divinylbenzene-based gel packing materials are defined as styrene-based columns.

[0085] Here, Figure 1 is a schematic graph showing the GPC measurement results using a styrene-based column and a silica-based column. As shown in Figure 1, in GPC measurements using a styrene-based column, no adsorption occurs, while in GPC measurements using a silica-based column, a portion of the polymer chain is adsorbed onto the silica, resulting in a difference in these results. In this invention, the adsorption rate of the polymer chain constituting the maximum peak (L) obtained by such measurements onto silica is defined.

[0086] In the conjugated diene polymer of the present invention, the adsorption rate of the polymer chain constituting the maximum peak (L) to silica is not particularly limited, but should be less than 40%, preferably 0 to 39%, more preferably 0 to 38%, and even more preferably 0 to 37%. By having the adsorption rate of the polymer chain constituting the maximum peak (L) to silica within the above range, the processability of the conjugated diene polymer, the strength properties, wear resistance properties, and low fuel consumption properties of the resulting rubber crosslinked product can be improved in a well-balanced manner.

[0087] The adsorption rate of the polymer chain constituting the maximum peak (L) to silica can be adjusted by, for example, adjusting the amount and type of vinyl compound units containing functional groups that can interact with silica, or by adjusting the amount and type of modifying groups contained in the polymer chain constituting the maximum peak (L).

[0088] In the conjugated diene polymer of the present invention, the peak top molecular weight of the maximum peak (L) is not particularly limited, but is preferably greater than 300,000, more preferably greater than 350,000, even more preferably greater than 600,000, particularly preferably greater than 600,000 and 2,500,000 or less, and most preferably between 650,000 and 1,500,000. By having the peak top molecular weight of the maximum peak (L) within the above range, the processability of the conjugated diene polymer, the strength properties, wear resistance properties, and low fuel consumption properties of the resulting rubber crosslinked product can be improved in a well-balanced manner.

[0089] In the conjugated diene polymer of the present invention, the content of polymer chains constituting the maximum peak (L) is not particularly limited, but is preferably 5 to 98% by weight, more preferably 10 to 80% by weight, even more preferably 20 to 70% by weight, preferably 25 to 70% by weight, preferably 30 to 70% by weight, and preferably 35 to 70% by weight, relative to the total weight of the conjugated diene polymer. By having the content of polymer chains constituting the maximum peak (L) within the above range, the processability of the conjugated diene polymer, the strength characteristics, wear resistance characteristics, and low fuel consumption characteristics of the resulting rubber crosslinked product can be further enhanced in a well-balanced manner. The content of polymer chains constituting the maximum peak (L) can be determined from the ratio of the peak area of ​​the maximum peak (L) to the peak area of ​​the molecular weight distribution curve of the conjugated diene polymer.

[0090] The conjugated diene polymer of the present invention is preferably one in which the molecular weight distribution curve has one or more peaks having a peak-top molecular weight greater than the peak-top molecular weight of the maximum peak (L). That is, the conjugated diene polymer of the present invention is preferably one in which the molecular weight distribution curve has at least the final detection peak (Z), the maximum peak (L) as a peak other than the final detection peak (Z), and a peak having a peak-top molecular weight greater than the peak-top molecular weight of the maximum peak (L). Having such a peak configuration in the molecular weight distribution curve allows for a balanced and further improvement in the processability of the conjugated diene polymer, as well as the strength, wear resistance, and fuel efficiency of the resulting rubber crosslinked product.

[0091] The weight-average molecular weight (Mw) of the conjugated diene polymer of the present invention is preferably in the range of 200,000 to 10,000,000, more preferably in the range of 200,000 to 5,000,000, even more preferably in the range of 300,000 to 5,000,000, even more preferably in the range of 400,000 to 3,000,000, particularly preferably in the range of 450,000 to 2,000,000, especially preferably in the range of 500,000 to 1,500,000, and most preferably in the range of 550,000 to 1,200,000. By setting the weight-average molecular weight (Mw) of the conjugated diene polymer within the above range, the processability of the conjugated diene polymer, the strength characteristics, wear resistance characteristics, and low fuel consumption characteristics of the resulting rubber crosslinked product can be further enhanced in a well-balanced manner.

[0092] The overall molecular weight distribution of the conjugated diene polymer of the present invention, expressed as the ratio (Mw / Mn) of the total weight-average molecular weight (Mw) to the number-average molecular weight (Mn), is preferably 1.5 or higher, more preferably 1.5 to 5, even more preferably 1.5 to 3, and particularly preferably 1.55 to 3.

[0093] In this specification, in the molecular weight distribution curve, the peak with the lowest molecular weight is defined as the first peak, and subsequent peaks are defined as the second peak, third peak, and so on, in order of decreasing molecular weight. The peak defined as the first peak is the final detection peak (Z). Furthermore, the molecular weight at which the molecular weight distribution curve shows a maximum value at each peak is defined as the peak-top molecular weight of each peak.

[0094] In the conjugated diene polymer of the present invention, for example, when the number of peaks in the molecular weight distribution curve is 3, the peak top molecular weight of the second peak is preferably in the range of 150,000 to 2,500,000, more preferably in the range of 200,000 to 1,500,000, even more preferably in the range of over 250,000 and up to 1,200,000, and particularly preferably in the range of 300,000 to 1,000,000. The peak top molecular weight of the second peak may be, for example, in the range of 600,000 to 2,500,000, in the range of 650,000 to 1,500,000, or in the range of 650,000 to 1,200,000. When the number of peaks in the molecular weight distribution curve is 3, the peak top molecular weight of the third peak is preferably in the range of 500,000 to 5,000,000, more preferably in the range of 600,000 to 5,000,000, even more preferably in the range of 700,000 to 5,000,000, particularly preferably in the range of 800,000 to 4,000,000, and most preferably in the range of 900,000 to 3,000,000.

[0095] In the conjugated diene polymer of the present invention, for example, when the number of peaks in the molecular weight distribution curve is 4, the peak top molecular weight of the second peak is preferably in the range of 120,000 to 700,000, more preferably in the range of 140,000 to 660,000, and even more preferably in the range of 160,000 to 620,000; the peak top molecular weight of the third peak is preferably in the range of 600,000 to 2,500,000, more preferably in the range of 650,000 to 1,500,000, and even more preferably in the range of 650,000 to 1,200,000; the peak top molecular weight of the fourth peak is preferably in the range of 700,000 to 5,000,000, more preferably in the range of 800,000 to 4,000,000, and even more preferably in the range of 900,000 to 3,000,000.

[0096] In the conjugated diene polymer of the present invention, for example, when the number of peaks in the molecular weight distribution curve is 5, the peak top molecular weight of the second peak is preferably in the range of 120,000 to 700,000, more preferably in the range of 140,000 to 660,000, and even more preferably in the range of 160,000 to 620,000; the peak top molecular weight of the third peak is preferably in the range of 160,000 to 1,000,000, more preferably in the range of 190,000 to 960,000, and even more preferably in the range of 220,000 to 920,000; the peak top molecular weight of the fourth peak is preferably in the range of 600,000 to 2,500,000, more preferably in the range of 650,000 to 1,500,000, and even more preferably in the range of 650,000 to 1,200,000; the peak top molecular weight of the fifth peak is preferably in the range of 700,000 to 5,000,000, more preferably in the range of 800,000 to 4,000,000, and even more preferably in the range of 900,000 to 3,000,000.

[0097] The weight-average molecular weight (Mw), molecular weight distribution (Mw / Mn), and peak-top molecular weight of each peak can be determined based on the molecular weight distribution curve obtained by measuring the number of peaks in the molecular weight distribution curve described above.

[0098] The conjugated diene polymer of the present invention preferably has a Mooney viscosity (ML1+4) of 10 to 200, more preferably 20 to 150, even more preferably 30 to 145, particularly preferably 40 to 140, and most preferably 50 to 135. When the Mooney viscosity is within the above range, processability is improved. The Mooney viscosity (ML1+4) is measured at 100°C according to JIS K6300-1:2013.

[0099] Furthermore, the conjugated diene polymer of the present invention can be preferably used in a state mixed with a spreading oil, as described later, from the viewpoint of ease of handling. When the conjugated diene polymer is used in a state mixed with a spreading oil, the Mooney viscosity (ML1+4) of the conjugated diene polymer mixed with the spreading oil can be determined as the Mooney viscosity (ML1+4) of the conjugated diene polymer. In this case, the preferred range and measurement conditions for the Mooney viscosity (ML1+4) are the same as those described above.

[0100] <Method for producing conjugated diene polymers> One example of a method for producing the conjugated diene polymer of the present invention is a method that includes the step of mixing two or more conjugated diene polymers having different molecular weight distribution curves in the state of polymer solution. In particular, a method that includes the step of mixing a polymer solution containing a low molecular weight conjugated diene polymer (described later) with a polymer solution containing a high molecular weight conjugated diene polymer (described later) (hereinafter sometimes referred to as the "first production method") is preferred.

[0101] <First manufacturing method> The first manufacturing method is a method comprising the step of mixing a polymer solution containing a low molecular weight conjugated diene polymer with a polymer solution containing a high molecular weight conjugated diene polymer. In the first manufacturing method, it is desirable to use at least one of the low molecular weight conjugated diene polymer or the high molecular weight conjugated diene polymer that has two or more peaks in the molecular weight distribution curve, so that the conjugated diene polymer finally obtained has three or more peaks in the molecular weight distribution curve.

[0102] In the first manufacturing method, among the low molecular weight conjugated diene polymers or molecular weight conjugated diene polymers used, those with a large weight-average molecular weight (Mw) are designated as high molecular weight conjugated diene polymers, and those with a small weight-average molecular weight (Mw) are designated as low molecular weight conjugated diene polymers.

[0103] In the first manufacturing method, it is preferable that the number of peaks in the molecular weight distribution curve of at least the high molecular weight conjugated diene polymer is 2 or more, and it is more preferable that the number of peaks in the molecular weight distribution curve of the low molecular weight conjugated diene polymer is 2 or more, and the number of peaks in the molecular weight distribution curve of the high molecular weight conjugated diene polymer is 2 or more.

[0104] The first manufacturing method includes a step of mixing a polymer solution containing a low molecular weight conjugated diene polymer with a polymer solution containing a high molecular weight conjugated diene polymer. As the first manufacturing method, from the viewpoint of easily and stably producing the conjugated diene polymer of the present invention in a high productivity, it is preferable to first produce a polymer solution containing a low molecular weight conjugated diene polymer and a polymer solution containing a high molecular weight conjugated diene polymer separately, and then mix them.

[0105] A preferred method for producing a polymer solution containing a low molecular weight conjugated diene polymer is, for example, by polymerizing a monomer mixture containing at least a conjugated diene monomer in an inert solvent using a polymerization initiator, i.e., by solution polymerization. Hereafter, such embodiments may simply be referred to as polymerization of low molecular weight conjugated diene polymers, etc.

[0106] The monomer mixture used in the polymerization of low molecular weight conjugated diene polymers contains at least a conjugated diene monomer. Examples of conjugated diene monomers include those similar to the conjugated diene monomers used to form conjugated diene monomer units as described above, and among these, 1,3-butadiene is preferred.

[0107] The monomer mixture used in the polymerization of low molecular weight conjugated diene polymers preferably contains aromatic vinyl monomers in addition to conjugated diene monomers, thereby introducing aromatic vinyl monomer units into the low molecular weight conjugated diene polymer. Examples of aromatic vinyl monomers include those similar to the aromatic vinyl monomers used to form aromatic vinyl monomer units as described above, and among these, styrene is preferred.

[0108] The monomer mixture used in the polymerization of low molecular weight conjugated diene polymers preferably further contains a vinyl compound containing a functional group that can interact with silica. Examples of vinyl compounds containing a functional group that can interact with silica include those similar to the vinyl compounds containing a functional group that can interact with silica used to form the units of the above-mentioned vinyl compound containing a functional group that can interact with silica.

[0109] The monomer mixture used in the polymerization of low molecular weight conjugated diene polymers may contain conjugated diene monomers and, if necessary, aromatic vinyl monomers and other monomers other than vinyl compounds containing functional groups that can interact with silica. Examples of such other monomers include those mentioned above, which constitute other monomer units.

[0110] The inert solvent used in the polymerization of low molecular weight conjugated diene polymers is not particularly limited as long as it is commonly used in solution polymerization and does not inhibit the polymerization reaction. Specific examples of inert solvents include linear 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 individually or in combination of two or more. The amount of inert solvent used is such that the monomer concentration is, for example, 1 to 50% by weight, preferably 10 to 40% by weight.

[0111] Polymerization initiators used in the polymerization of low molecular weight conjugated diene polymers are not particularly limited, as long as they can polymerize monomer mixtures containing conjugated diene monomers. Specific examples include polymerization initiators that primarily use organoalkali metal compounds, organoalkaline earth metal compounds, and lanthanum series metal compounds as catalysts. Examples of organoalkali metal compounds include organolithium compounds, organosodium compounds, and organokatum compounds. Specifically, examples include organomonolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenithium; organopolyvalent 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 organokatum 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, and diketilbarium. Examples of polymerization initiators using lanthanum series metal compounds as the main catalyst include a salt of a lanthanum series metal, such as lanthanum, cerium, praseodymium, neodymium, samarium, or gadolinium, with a carboxylic acid or phosphorus-containing organic acid as the main catalyst, and a polymerization initiator consisting of this and co-catalysts such as alkylaluminum compounds, organoaluminum hydride compounds, and organoaluminum halide compounds. 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.Furthermore, the organoalkali metal compounds may be reacted beforehand with secondary amine compounds such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, piperidine, hexamethyleneimine, and heptamethyleneimine to be used as organoalkali metal amide compounds. By using organoalkali metal amide compounds as polymerization initiators, the resulting rubber crosslinked products can be made to have better fuel efficiency and wear resistance. These polymerization initiators may be used individually or in combination of two or more.

[0112] Examples of organoalkali metal amide compounds include those obtained by reacting an organoalkali 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, R 17 , R 18 Each of these independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an amino group protecting group, or a group that can be hydrolyzed to produce a hydroxyl group, R 17 and R 18 These atoms may bond to each other and form a ring structure with the nitrogen atom to which they bond. In the case of forming such a ring structure, they may form the ring structure with heteroatoms other than the nitrogen atom to which they bond, in addition to the nitrogen atom to which they bond.

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

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

[0115] The aryl group is not particularly limited, but an aryl group having 6 to 12 carbon atoms is preferred, and an aryl group having 6 to 10 carbon atoms is more preferred. 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 an aralkyl group having 7 to 13 carbon atoms is preferred, and an aralkyl group having 7 to 9 carbon atoms is more preferred. Examples of such aralkyl groups include the benzyl group and the phenethyl group.

[0117] The protecting group for the amino group is not particularly limited and can be any group that acts as a protecting group for the amino group, but examples include alkylsilyl groups. Examples of such alkylsilyl groups include trimethylsilyl group, triethylsilyl group, triphenylsilyl group, methyldiphenylsilyl group, ethylmethylphenylsilyl group, and tert-butyldimethylsilyl group.

[0118] Note, R 17 , and / or R 18 When is an amino group protecting group, the removal of the amino group protecting group results in the formation of a low molecular weight conjugated diene polymer at one end of the polymer chain, in the general formula (12) described later, R 19 , and / or R 20 A structure in which a hydrogen atom is present can be introduced.

[0119] The groups that can be hydrolyzed to produce hydroxyl groups are not particularly limited; for example, any group that can produce hydroxyl groups by hydrolysis in the presence of an acid, etc., can be used. Examples include alkoxyalkyl groups and groups containing epoxy groups.

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

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

[0122] Also, R 17 and R 18 They may be bonded to each other, forming a ring structure with the nitrogen atom to which they are bonded, and in this case, R 17 and R 18 A concrete example of a structure formed by this and the nitrogen atom bonded to it is an azetidine ring (R 17 and R 18 However, propylene group, pyrrolidine ring (R 17 and R 18 However, butylene group), piperidine ring (R 17 and R 18 However, the pentylene group, the hexamethyleneimine ring (R 17 and R 18 However, examples include the hexylene group. 17 and R 18 When these elements bond to each other and form a ring structure with the nitrogen atoms to which they bond, the ring structure is preferably a 4- to 8-membered ring structure.

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

[0124] When the compound represented by the above general formula (10) is used as a polymerization initiator, the amine structure that forms the organoalkali metal amide compound remains attached to the polymerization initiation end of the polymer chain. Therefore, when the compound represented by the above general formula (10) is used as a polymerization initiator, the structure represented by the following general formula (12) is introduced to one end of the polymer chain that forms the resulting low molecular weight conjugated diene polymer. R 19 -N(-R 20 )- (12) In general formula (12), R 19 , R 20 Each of these independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an amino group protecting group, or a group that can be hydrolyzed to produce a hydroxyl group, R 19 and R 20 These atoms may bond to each other and form a ring structure with the nitrogen atom to which they bond. In the case of forming such a ring structure, they may form the ring structure with heteroatoms other than the nitrogen atom to which they bond, in addition to the nitrogen atom to which they bond.

[0125] R 19 , R 20 The alkyl, cycloalkyl, aryl, aralkyl, amino protecting groups, or groups that can be hydrolyzed to produce a hydroxyl group are R in general formula (10). 17 , R 18 We can list the same things, and also R 19 and R 20 Even when they bond to each other and form a ring structure with the nitrogen atom to which they bond, the R in general formula (10) 17 , R 18 It can be treated as the same as R.19 , R 20 The hydrogen atom that can become part of the amino group is introduced when the protecting group of the amino group is removed.

[0126] The method for adding the organoalkali metal amide compound as a polymerization initiator to the polymerization system is not particularly limited. One method is to first react the organoalkali metal compound with a secondary amine compound to obtain the organoalkali metal amide compound, and then mix this with a monomer containing a conjugated diene monomer to proceed with the polymerization reaction. Alternatively, one can add the organoalkali metal compound and the secondary amine compound separately to the polymerization system and mix them with a monomer containing a conjugated diene monomer to generate the organoalkali metal amide compound in the polymerization system, thereby proceeding with the polymerization reaction. The reaction conditions, such as the reaction temperature, are not particularly limited and can be, for example, according to the desired polymerization reaction conditions.

[0127] The amount of secondary amine compound used should be determined according to the amount of polymerization initiator added, but it is usually in the range of 0.01 to 1.5 millimoles, preferably 0.1 to 1.2 millimoles, and more preferably 0.5 to 1.0 millimoles per millimole of organoalkali metal compound.

[0128] In the polymerization of low molecular weight conjugated diene polymers, the amount of polymerization initiator used is not particularly limited, but is preferably in the range of 1 to 100 mmol, more preferably 2 to 50 mmol, per 1000 g of monomer.

[0129] The polymerization temperature is typically in the range of -80 to +150°C, preferably 0 to 100°C, and more preferably 30 to 90°C. Any polymerization method, such as batch or continuous, can be used, but the batch method is preferred because it allows for easier control of the randomness of the bonding between conjugated diene monomer units and aromatic vinyl monomer units.

[0130] Furthermore, when polymerizing monomer mixtures containing conjugated diene monomers, it is preferable to add polar compounds to the inert organic solvent in order to adjust the vinyl bond content in the conjugated diene monomer units in the low molecular weight conjugated diene 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, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, and tertiary amines are more preferred, tertiary amines are even more preferred, and tetramethylethylenediamine is particularly preferred. These polar compounds may be used individually or in combination of two or more. The amount of polar compound used should be determined according to the desired vinyl bond content, and is preferably 0.001 to 100 moles, more preferably 0.01 to 10 moles, per mole of polymerization initiator. When the amount of polar compounds 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 polymerization initiators are less likely to occur.

[0131] A low molecular weight conjugated diene polymer may be obtained by a manufacturing method comprising the steps of: polymerizing a monomer (a) containing isoprene in an inert solvent with 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 and to obtain polymer blocks (A) and polymer blocks (B).

[0132] By employing such a manufacturing method, the low molecular weight conjugated diene polymer can be made to include a polymer block (A) containing isoprene monomer units and a polymer block (B) containing 1,3-butadiene monomer units, which are formed in a continuous manner.

[0133] The monomer (a) for forming the polymer block (A) can be any monomer containing isoprene, and the monomer should be one that corresponds to the composition of the polymer block (A) to be formed. For example, if the polymer block (A) consists of isoprene monomer units and aromatic vinyl monomer units, then monomer (a) should contain isoprene and aromatic vinyl monomers. Furthermore, if the polymer block (A) has units of a vinyl compound containing a functional group that can interact with silica, in addition to isoprene monomer units and aromatic vinyl monomer units, then monomer (a) should contain isoprene and aromatic vinyl monomers, in addition to a vinyl compound containing a functional group that can interact with silica. Such embodiments will be described below.

[0134] The polymer block (A) is not particularly limited as long as it contains isoprene monomer units, and may consist only of isoprene monomer units, or it may consist of isoprene monomer units and monomer units other than isoprene monomer units. In this case, aromatic vinyl monomer units are preferably given as monomer units other than isoprene monomer units, and it is preferable that the polymer block (A) contains aromatic vinyl monomer units in addition to isoprene monomer units.

[0135] 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 setting the content of isoprene monomer units in polymer block (A) within the above range, the affinity between the low molecular weight conjugated diene polymer and fillers such as silica can be further increased, thereby improving the processability of the conjugated diene polymer and the wear resistance and fuel efficiency of the resulting rubber crosslinked product in a well-balanced manner.

[0136] The aromatic vinyl monomer used to constitute the aromatic vinyl monomer units contained in polymer block (A) can be the same as the aromatic vinyl monomers described above, and among these, styrene is preferred. These aromatic vinyl monomers may be used individually or in combination of two or more. The content of aromatic vinyl monomer units in 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 aromatic vinyl monomer units is not particularly limited, but is preferably 1% by weight or more.

[0137] Furthermore, at least one of the polymer block (A) and polymer block (B), described later, that constitute the low molecular weight conjugated diene polymer may contain units of a vinyl compound containing a functional group capable of interacting with silica. In this case, the units of the vinyl compound containing a functional group capable of interacting with silica may be contained only in polymer block (A), only in polymer block (B), or in the polymer It may be in any form that it is contained in both block (A) and polymer block (B).

[0138] The content of units of the vinyl compound containing a functional group that can interact with silica is preferably adjusted to a range of 0.01 to 20% by weight, more preferably 0.02 to 2% by weight, and particularly preferably 0.03 to 1% by weight, relative to the total monomer units constituting the low molecular weight conjugated diene polymer, whether it is included in polymer block (A), polymer block (B), or both. By setting the content of units of the vinyl compound containing a functional group that can interact with silica within the above range, the conjugated diene polymer can be made to have a better balance of processability, wear resistance and fuel efficiency of the resulting rubber crosslinked product, and furthermore, handling stability can be improved.

[0139] Polymer block (A) may optionally contain isoprene monomer units, as well as aromatic vinyl monomer units and units of vinyl compounds containing functional groups that can interact with silica, if necessary, and other monomer units. Other compounds used to constitute the other monomer units include chain 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 unconjugated diene monomers such as 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene. These other monomers can be used individually or in combination of two or more. The content of other monomer units in 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.

[0140] Polymer block (A) is formed by polymerizing monomer (a) containing isoprene in an inert solvent with a polymerization initiator. The formed polymer block (A) has active ends.

[0141] To form polymer block (A), the same inert solvent as described above can be used for monomer polymerization. The amount of inert solvent used is preferably such that the monomer concentration is 1 to 80% by weight, and more preferably 10 to 50% by weight.

[0142] The polymerization initiator used to form the polymer block (A) is not particularly limited, as long as it can polymerize the monomer (a) containing isoprene to give a polymer chain having an active end. Specific examples include those used in the polymerization initiator described above.

[0143] The amount of polymerization initiator used can be determined according to 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 monomer (a) containing isoprene.

[0144] The polymerization temperature when polymerizing monomer (a) containing isoprene 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 can be used, such as batch or continuous polymerization. Furthermore, when polymer block (A) is used as a copolymer chain, the bonding mode of each monomer can be various, such as block-like, tapered, and random.

[0145] Furthermore, in order to adjust the vinyl bond content in the isoprene monomer units in polymer block (A), it is preferable to add a polar compound to the inert solvent during polymerization. The same polar compound as described above can be used. The amount of polar compound used should be determined according to the desired vinyl bond content, preferably 0.01 to 30 moles, and more preferably 0.05 to 10 moles, per mole of polymerization initiator. When the amount of 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 less likely to occur. In addition, by increasing the amount of polar compound used within the above range, the vinyl bond content in the isoprene monomer units can be increased.

[0146] The vinyl bond content in the isoprene monomer units in polymer block (A) is preferably 5 to 90% by weight, and more preferably 5 to 80% by weight. By setting the vinyl bond content in the isoprene monomer units within the above range, the low fuel consumption characteristics of the resulting crosslinked rubber can be further improved. In this specification, the vinyl bond content in the isoprene monomer units refers to the ratio 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 unit.

[0147] 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) within the above range, the low fuel consumption characteristics of the resulting rubber crosslinked product can be further improved.

[0148] Furthermore, the molecular weight distribution of polymer block (A), expressed as the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) (Mw / Mn), is preferably 1.0 to 1.5, and more preferably 1.0 to 1.3. When the molecular weight distribution (Mw / Mn) of polymer block (A) is within the above range, the production of low molecular weight conjugated diene polymers becomes easier, and the production of the conjugated diene polymer of the present invention becomes easier. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polymer block (A) can be determined as polystyrene equivalent values ​​by gel permeation chromatography.

[0149] Polymer block (B) is not particularly limited as long as it contains 1,3-butadiene monomer units, and may consist only of 1,3-butadiene monomer units, or it may consist of 1,3-butadiene monomer units and monomer units other than 1,3-butadiene monomer units. In this case, aromatic vinyl monomer units are preferably given as monomer units other than 1,3-butadiene monomer units, and it is preferable that polymer block (B) contains aromatic vinyl monomer units in addition to 1,3-butadiene monomer units.

[0150] The content of 1,3-butadiene monomer units in 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 polymer block (B) within the above range, the production of low molecular weight conjugated diene polymers becomes easier, and as a result, the production of the conjugated diene polymer of the present invention becomes easier.

[0151] The aromatic vinyl monomer used to constitute 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 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.

[0152] Furthermore, at least one of polymer block (A) and polymer block (B) may contain a unit of a vinyl compound that has a functional group capable of interacting with silica.

[0153] Furthermore, polymer block (B) may optionally contain other monomer units in addition to 1,3-butadiene monomer units and, if necessary, aromatic vinyl monomer units and units of vinyl compounds containing functional groups that can interact with silica. Other compounds constituting such other monomer units include those similar to those exemplified in polymer block (A) above (except 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.

[0154] Polymer block (B) is formed in succession with polymer block (A) by mixing polymer block (A), which has the active ends described above, with monomer (b) containing 1,3-butadiene and continuing the polymerization reaction. The formed polymer block (B) has active ends. On the other hand, the active ends disappear from polymer block (A).

[0155] The inert solvent used for polymerization of polymer block (A) and monomer (b) containing 1,3-butadiene to form polymer block (B) is not particularly limited, and the same inert solvent as described above can be used.

[0156] The amount of polymer block (A) having an active end used when forming polymer block (B) can be determined according to the desired 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.

[0157] The method of mixing the polymer block (A) and the monomer (b) containing 1,3-butadiene is not particularly limited. The polymer block (A) having active ends 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) containing active ends. From the viewpoint of controlling polymerization, the method of adding the polymer block (A) having active ends to a solution of the monomer (b) containing 1,3-butadiene is preferred.

[0158] The polymerization temperature when polymerizing 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 can be used, such as batch or continuous polymerization. When the polymer block (B) is a copolymer chain, batch polymerization is preferred because it allows for easier control of the randomness of the bonds.

[0159] When the polymer block (B) is used as a copolymer chain, the bonding mode of each monomer can be various, such as block-like, tapered, and random. Among these, the random bond is preferred. By using a random bond, the low fuel consumption characteristics of the resulting rubber crosslinked material can be further improved.

[0160] Furthermore, in the first manufacturing method, in order to adjust the vinyl bond content in the 1,3-butadiene monomer units in polymer block (B), it is preferable to add a polar compound to the inert solvent during polymerization, similar to the method used to adjust the vinyl bond content in the isoprene monomer units in polymer block (A). However, if a sufficient amount of the polar compound to adjust the vinyl bond content in the 1,3-butadiene monomer units in polymer block (B) has already been added to the inert solvent during the preparation of polymer block (A), it is not necessary to add a new polar compound. The same polar compound as described above can be used to adjust the vinyl bond content. The amount of polar compound used should be determined according to the desired vinyl bond content, preferably within the range of 0.01 to 100 moles, more preferably 0.1 to 30 moles, relative to 1 mole of polymerization initiator used in the initial polymerization reaction (polymerization reaction to form the first polymer block (A)). When the amount of 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 less likely to occur.

[0161] The vinyl bond content in the 1,3-butadiene monomer units in 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 polymer block (B) within the above range, the resulting rubber crosslinked product can be made to have even better fuel efficiency characteristics.

[0162] In this way, a polymer chain having an active end, comprising polymer block (A) and polymer block (B), can be obtained. From the viewpoint of productivity, it is preferable that the polymer chain having an active end is composed of polymer block (A)-polymer block (B), and that the end of polymer block (B) is the active end. However, it may also have multiple polymer blocks (A) or other polymer blocks. For example, a polymer chain having an active end such as polymer block (A)-polymer block (B)-polymer block (A) can be mentioned. In this case, the active end will be formed at the end of polymer block (A) formed following polymer block (B). When forming polymer block (A) on the active end side of a polymer chain having an active end, the amount of isoprene used is preferably 10 to 100 moles, more preferably 15 to 70 moles, and particularly preferably 20 to 35 moles, per mole of polymerization initiator used in the first polymerization reaction (polymerization reaction to form the first polymer block (A)).

[0163] In a polymer chain having an active end, the weight ratio of polymer block (A) to polymer block (B) (if there are multiple polymer blocks (A) and polymer blocks (B), the weight ratio is based on the total weight of each) is preferably 0.001 to 0.2, more preferably 0.005 to 0.1, and particularly preferably 0.01 to 0.05, which is (weight of polymer block (A)) / (weight of polymer block (B)). 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 a better balance of processability, wear resistance, and low fuel consumption characteristics of the resulting rubber crosslinked product.

[0164] As described above, a polymer containing polymer chains with active ends can be obtained in an inert solvent.

[0165] A coupling polymer chain may be formed by reacting at least a portion of the polymer chain containing the active end with a coupling agent. This allows for control over the number of peaks in the molecular weight distribution curve of the low molecular weight conjugated diene polymer.

[0166] Examples of coupling agents, though not particularly limited, 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, it is preferable to use a coupling agent with three or more functions, and even more preferable to use a coupling agent with four or more functions, from the viewpoint of being able to improve the mechanical properties of the resulting rubber crosslinked product while sufficiently maintaining the processability of the conjugated diene polymer.

[0167] The amount and timing of coupling agent use are not particularly limited and should be determined according to the molecular weight distribution curve of the low molecular weight conjugated diene polymer to be obtained.

[0168] Furthermore, from the viewpoint of making the effects of the present invention more pronounced, it is preferable to make the low molecular weight conjugated diene polymer have a modified group by reacting a modifying agent with the active ends contained in the polymer chain containing the active ends obtained by polymerization (including polymer chains containing active ends that exist in the system after the coupling reaction). As the modifying agent, the above-mentioned modifying agents for forming the modified group can be used. In addition, by using a modifying agent that can exert a coupling effect (for example, a polyorganosiloxane), the number of peaks in the molecular weight distribution curve of the low molecular weight conjugated diene polymer can be controlled.

[0169] When using a siloxane compound as a modifier, it is preferable to react the polymer chain having an active end with the siloxane compound and an organometallic compound, thereby improving the processability of the conjugated diene polymer. Examples of organometallic compounds used in this process include organoalkali metal compounds, such as organolithium compounds, organosodium compounds, and organocatum compounds. Specifically, examples include organomonolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stilbenithium; organopolyvalent lithium compounds such as dilythiomethane, 1,4-dilythiobutane, 1,4-dilythio-2-ethylcyclohexane, 1,3,5-trilythiobenzene, and 1,3,5-tris(lithiomethyl)benzene; organosodium compounds such as sodium naphthalene; and organocatum compounds such as potassium naphthalene. Among these organometallic compounds, n-butyllithium is preferably used. Furthermore, the amount of organometallic compound used in this process 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 organometallic compound used is within the above range, the conjugated diene polymer can be made even more processable. The organometallic compound may be used alone or in combination of two or more types.

[0170] Methods for reacting a polymer chain having active ends with a siloxane compound and an organometallic compound include, for example, mixing the polymer chain having active ends with the siloxane compound and then mixing in the organometallic compound; mixing the polymer chain having active ends with the organometallic compound and then mixing in the siloxane compound; and simultaneously adding the siloxane compound and the organometallic compound to the polymer chain having active ends (or adding the siloxane compound and the organometallic compound consecutively) and then mixing them. From the viewpoint of further improving the processability of the conjugated diene polymer, the method of mixing the polymer chain having active ends with the organometallic compound and then mixing in the siloxane compound is preferred.

[0171] In a method for mixing a polymer chain having active ends with an organometallic compound, followed by a siloxane compound, it is preferable and convenient to add the organometallic compound to the polymer solution used for polymerization to obtain the polymer chain having active ends, mix it, and then add the siloxane compound to the mixed solution. In this case, it is preferable to dissolve the organometallic compound in an inert solvent and add it to the polymer solution, and the concentration of the solution is preferably in the range of 1 to 50% by weight. The temperature when adding the organometallic compound is not particularly limited, but is usually 0 to 120°C.

[0172] While there are no particular limitations on the timing of adding organometallic compounds to a solution containing polymer chains with active ends, it is preferable to add the organometallic compounds to the solution after the polymerization conversion rate has reached 90% or more, more preferably 95% or more, from the viewpoint of increasing the reactivity of the siloxane compound in the presence of the organometallic compounds. Furthermore, it is preferable to add the organometallic compounds to the solution when the monomer concentration is 5000 ppm or less.

[0173] When adding a siloxane compound to a solution containing a polymer chain having an active end and an organometallic compound, it is preferable to dissolve the siloxane compound in an inert solvent and add it to the polymerization system, and the concentration of the solution is preferably in the range of 1 to 50% by weight. The reaction temperature when reacting the siloxane compound is not particularly limited, but is usually 0 to 120°C, and the reaction time is not particularly limited, but is usually 1 to 60 minutes.

[0174] Furthermore, the timing of adding the siloxane compound to the solution containing the polymer chain having active ends and the organometallic compound is not particularly limited as long as it is done after the organometallic compound has been added to the solution containing the polymer chain having active ends. However, it is desirable to add the organometallic compound to the solution containing the polymer chain having active ends, mix it for 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. By adding the siloxane compound in this manner, the processability of the conjugated diene polymer can be further improved.

[0175] Furthermore, the polymer chain obtained by mixing a polymer chain having an active end with an organometallic compound, and then mixing with a siloxane compound, includes polymer chains in which a modified structure due to the siloxane compound has been introduced at the polymer chain ends and in which the organometallic compound has reacted further. However, it may also include unmodified polymer chains that have not been modified by the siloxane compound, or siloxane-modified polymer chains in which the organometallic compound has not reacted.

[0176] When reacting the above-mentioned modifying agent with the active ends of the polymer chain, the amount of modifying agent used is not particularly limited, but it is preferably 0.01 to 10.0 moles, more preferably 0.02 to 5.0 moles, and particularly preferably 0.05 to 2.0 moles, as the amount of modifying agent per mole of active ends of the polymer chain having active ends (or, in the case of using an organoalkali metal compound as a polymerization initiator, the amount of modifying agent per mole of metal atoms in the organoalkali metal compound). Note that the modifying agents may be used individually or in combination of two or more types.

[0177] Furthermore, there are no particular limitations on the method of reacting the active ends of a polymer chain having active ends with a modifying agent, but one example is to mix the polymer chain having active ends and the modifying agent in a solvent in which they can be dissolved. The solvent used in this case can be one of those exemplified above as the solvent used for polymerization. In this case, it is simpler and preferable to leave the polymer chain having active ends obtained above in the polymer solution used for polymerization and add the modifying agent to it. In this case, the modifying agent may be dissolved in the inert solvent used for polymerization and added to the polymerization system, and the concentration of the solution is preferably in the range of 1 to 50% by weight. The reaction temperature is not particularly limited, but is usually 0 to 120°C, and the reaction time is not particularly limited, but is usually 1 minute to 1 hour.

[0178] The timing of adding a denaturing agent to a solution containing polymer chains with active ends is not particularly limited, but it is desirable to add the denaturing agent when the polymerization reaction is not yet complete and the solution containing polymer chains with active ends also contains monomers, more specifically, when the solution containing polymer chains with active ends contains 100 ppm or more, more preferably 300 to 50,000 ppm, of monomers. By adding the denaturing agent in this manner, it is possible to suppress side reactions between the polymer chains with active ends and impurities contained in the polymerization system, thereby enabling good control of the reaction.

[0179] It is preferable to add a polymerization terminator such as an alcohol such as methanol and isopropanol or water to the polymer chain having an active end obtained by coincidence to deactivate the unreacted active end. By the above method, a polymer solution of a low molecular weight conjugated diene polymer can be obtained.

[0180] To the polymer solution containing a low molecular weight conjugated diene polymer obtained by the above method, an antioxidant such as a phenolic stabilizer, a phosphorus stabilizer, or a sulfur stabilizer may be added if desired. The addition amount of the antioxidant may be appropriately determined according to its type and the like. Further, if desired, an extender oil may be blended to obtain an oil-extended rubber. Examples of the extender oil include paraffinic, aromatic, and naphthenic petroleum softeners, vegetable softeners, and fatty acids. When using a petroleum softener, it is preferable that the content of polycyclic aromatics extracted by the method of IP346 (the test method of THE INSTITUTE PETROLEUM in the UK) is less than 3%. When using an extender oil, the amount used is usually 5 to 100 parts by weight based on 100 parts by weight of the conjugated diene polymer.

[0181] The weight average molecular weight (Mw) of the low molecular weight conjugated diene polymer used in the first production method is preferably in the range of 50,000 to 1,000,000, more preferably in the range of 80,000 to 900,000, and even more preferably in the range of 80,000 to 800,000. Further, the molecular weight distribution (Mw / Mn) of the low molecular weight conjugated diene polymer is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and even more preferably 1.0 to 2.0.

[0182] The polymer solution containing a high molecular weight conjugated diene polymer used in the first production method is preferably obtained by a solution polymerization method, similarly to the polymer solution containing a low molecular weight conjugated diene polymer described above.

[0183] The monomer mixture used for the polymerization of the high molecular weight conjugated diene polymer contains at least a conjugated diene monomer. Examples of the conjugated diene monomer include the same ones as those of the conjugated diene monomer for forming the conjugated diene monomer unit described above, and among these, 1,3-butadiene is preferable.

[0184] The monomer mixture used for the polymerization of the high molecular weight conjugated diene polymer preferably contains an aromatic vinyl monomer in addition to the conjugated diene monomer. Examples of the aromatic vinyl monomer include the same ones as those of the aromatic vinyl monomer for forming the aromatic vinyl monomer unit described above, and among these, styrene is preferable. The monomer mixture used for the polymerization of the high molecular weight conjugated diene polymer may further contain a vinyl compound having a functional group capable of interacting with the above-described silica and other monomers.

[0185] Examples of the inert solvent used for the polymerization of the high molecular weight conjugated diene polymer include the same ones as those used for the polymerization of the low molecular weight conjugated diene polymer, and the preferred types and usage amounts are also the same.

[0186] Examples of the polymerization initiator used for the polymerization of the high molecular weight conjugated diene polymer include the same ones as those used for the polymerization of the low molecular weight conjugated diene polymer, and the preferred types are also the same. Further, similar to the polymerization of the low molecular weight conjugated diene polymer, when an organic alkali metal compound is used as the polymerization initiator, it may be reacted with a secondary amine compound in advance and used as an organic alkali metal amide compound. The type of the secondary amine compound, the method of adding the organic alkali metal amide compound as the polymerization initiator to the polymerization system, and the usage amount of the secondary amine compound are not particularly limited, and may be the same as those in the polymerization of the low molecular weight conjugated diene polymer. The usage amount of the polymerization initiator in the polymerization of the high molecular weight conjugated diene polymer is not particularly limited, but is preferably in the range of 0.5 to 50.0 mmol, more preferably 1 to 10 mmol, per 1000 g of the monomer.

[0187] The polymerization temperature and polymerization method for high molecular weight conjugated diene polymers are not particularly limited and can be the same as for low molecular weight conjugated diene polymers.

[0188] In the polymerization of high molecular weight conjugated diene polymers, it is preferable to add a polar compound to the inert organic solvent when polymerizing the monomer mixture, similar to the polymerization of low molecular weight conjugated diene polymers. The type and amount of polar compound used are not particularly limited and can be the same as in the polymerization of low molecular weight conjugated diene polymers.

[0189] Furthermore, high molecular weight conjugated diene polymers may also be obtained by a manufacturing method comprising the steps of: polymerizing a monomer (a) containing isoprene in an inert solvent with 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 and obtain polymer block (A) and polymer block (B). In this case, the monomer composition of polymer block (A) and the method of forming polymer block (A) are not particularly limited and may be the same as for the polymerization of low molecular weight conjugated diene polymers. Also, the vinyl bond content in the isoprene monomer units in polymer block (A), the weight-average molecular weight (Mw) of polymer block (A), and the molecular weight distribution (Mw / Mn) of polymer block (A) are not particularly limited and may be the same as for the polymerization of low molecular weight conjugated diene polymers. Furthermore, the monomer composition of polymer block (B) and the method of forming polymer block (B) are not particularly limited and can be carried out in the same manner as the polymerization of low molecular weight conjugated diene polymers.

[0190] In this way, a polymer chain having an active end, comprising polymer block (A) and polymer block (B), can be obtained in the manufacturing process of a high molecular weight conjugated diene polymer. From the viewpoint of productivity, it is preferable that the polymer chain having an active end is composed of polymer block (A)-polymer block (B), and that the end of polymer block (B) is the active end. However, it may also have multiple polymer blocks (A) or other polymer blocks. For example, a polymer chain having an active end such as polymer block (A)-polymer block (B)-polymer block (A) can be mentioned. In this case, the active end will be formed at the end of polymer block (A) formed following polymer block (B). When forming polymer block (A) on the active end side of a polymer chain having an active end, the amount of isoprene used is not particularly limited and can be the same as in the case of a low molecular weight conjugated diene polymer.

[0191] The weight ratio of polymer block (A) to polymer block (B) in a polymer chain having an active end is not particularly limited and can be the same as in the case of low molecular weight conjugated diene polymers.

[0192] When producing high molecular weight conjugated diene polymers, a method may be adopted in which monomers mainly containing conjugated diene monomers are added to the polymerization system when the polymerization conversion rate is preferably 0% by weight or more, more preferably 10% by weight or more, similar to the case of low molecular weight conjugated diene polymers. By adopting such a method, segments containing a high proportion of conjugated diene monomers can be introduced to the polymer chain ends. In this case, the weight of conjugated diene monomers added after the start of polymerization relative to the total weight of monomers added after the start of polymerization, the content of conjugated diene monomer units in the segment, and the monomer composition of the segment are not particularly limited and may be the same as in the case of low molecular weight conjugated diene polymers.

[0193] As described above, a polymer containing polymer chains with active ends can be obtained in an inert solvent.

[0194] A coupling polymer chain may be formed by reacting at least a portion of the polymer chain containing the active end with a coupling agent. This allows for control over the number of peaks in the molecular weight distribution curve of the high molecular weight conjugated diene polymer. The type, amount, and timing of the coupling agent are not particularly limited and can be the same as those used for the polymerization of low molecular weight conjugated diene polymers.

[0195] Furthermore, from the viewpoint of making the effects of the present invention more pronounced, it is preferable to make the high molecular weight conjugated diene polymer have a modified group by reacting a modifying agent with the active ends contained in the polymer chain containing the active ends obtained by polymerization (including the polymer chain containing the active ends after the coupling reaction). The type of modifying agent, the amount of modifying agent used, the reaction conditions, and the timing of adding the modifying agent are not particularly limited and may be the same as for the polymerization of low molecular weight conjugated diene polymers. In addition, by using a modifying agent that can exert a coupling effect (for example, a polyorganosiloxane), the number of peaks in the molecular weight distribution curve of the high molecular weight conjugated diene polymer can be controlled.

[0196] When using a siloxane compound as a modifier, it is preferable to react the polymer chain having an active end with the siloxane compound and the organometallic compound. The specific details, such as the type and amount of organometallic compound used, the reaction method, the timing of adding the organometallic compound, the manner in which the siloxane compound is added, and the timing of adding the siloxane compound, can be the same as those for the polymerization of low molecular weight conjugated diene polymers.

[0197] It is preferable to add a polymerization inhibitor such as methanol, an alcohol such as isopropanol, or water to the polymer chain having active ends obtained by polymerization to deactivate the unreacted active ends. By the above method, a polymer solution of a high molecular weight conjugated diene polymer can be obtained.

[0198] The polymer solution containing the high molecular weight conjugated diene polymer obtained by the above method may optionally contain antioxidants and spreading oils, similar to the polymer solution of the low molecular weight conjugated diene polymer.

[0199] The weight-average molecular weight (Mw) of the high molecular weight conjugated diene polymer used in the first manufacturing method is preferably in the range of 500,000 to 5,000,000, more preferably in the range of 550,000 to 3,000,000, and even more preferably in the range of 600,000 to 2,000,000. Furthermore, the molecular weight distribution (Mw / Mn) of the high molecular weight conjugated diene polymer is preferably 1.0 to 5.0, more preferably 1.0 to 3.0, and even more preferably 1.0 to 2.0.

[0200] In the first manufacturing method, the conjugated diene polymer of the present invention can be obtained in polymer solution form by mixing a polymer solution containing the low molecular weight conjugated diene polymer obtained in this manner with a polymer solution containing the high molecular weight conjugated diene polymer. The mixing method is not particularly limited, and for example, one method is to add the polymer solution containing the low molecular weight conjugated diene polymer and the polymer solution containing the high molecular weight conjugated diene polymer to a mixing container and stir.

[0201] The conjugated diene polymer obtained in this way can then be separated from the reaction mixture by removing the solvent using any method, such as steam stripping or heating the mixture under reduced pressure, to obtain a solid conjugated diene polymer.

[0202] The method for producing the conjugated diene polymer of the present invention is not limited to the above first production method. For example, it may be a production method including a step of mixing three or more conjugated diene polymers having different molecular weight distribution curves in a polymer solution containing the conjugated diene polymer. The polymer solutions containing three or more conjugated diene polymers having different molecular weight distribution curves used in this case can be obtained by adjusting polymerization conditions, coupling reaction conditions, modification reaction conditions, etc. according to the composition, molecular weight distribution curve, etc. of each target conjugated diene polymer in the same polymerization method as the polymerization of the polymer solution containing the above-mentioned low molecular weight conjugated diene polymer. Further, the mixing method of the polymer solutions containing three or more conjugated diene polymers having different molecular weight distribution curves is not particularly limited, and the mixing method in the above first production method, etc. can be adopted.

[0203] As a method for producing the conjugated diene polymer of the present invention, a production method including a step of starting the polymerization of a monomer mixture containing a conjugated diene monomer using a polymerization initiator and then further adding a polymerization initiator to the polymerization system to continue the polymerization is also preferable. Such a production method is not particularly limited, and for example, a second production method described later and a third production method described later can be mentioned.

[0204] <The second production method> As a method for producing the conjugated diene polymer of the present invention, there is a production method (hereinafter sometimes referred to as the "second production method") in which after starting the polymerization of a monomer mixture containing a conjugated diene monomer using a polymerization initiator, a polymerization initiator is further added to the polymerization system and the polymerization is continued, and the additional addition operation of the polymerization initiator is performed two or more times.

[0205] The monomer mixture used in the second manufacturing method includes at least a conjugated diene monomer. Examples of conjugated diene monomers include those similar to the conjugated diene monomers used to form conjugated diene monomer units described above, with 1,3-butadiene being preferred. In addition to the conjugated diene monomer, the monomer mixture may include aromatic vinyl monomers similar to the aromatic vinyl monomers used to form aromatic vinyl monomer units described above, with styrene being preferred. The monomer mixture used in the second manufacturing method further preferably contains a vinyl compound containing a functional group capable of interacting with silica. The monomer mixture used in the second manufacturing method may also contain other monomers described above.

[0206] The inert solvent used in the second manufacturing method is the same as that used in the polymerization of the low molecular weight conjugated diene polymer in the first manufacturing method, and the preferred type and amount used are also the same.

[0207] In the second manufacturing method, the polymerization initiator used when initiating polymerization and the polymerization initiator used in the additional addition operation are the same as those used in the polymerization of low molecular weight conjugated diene polymers in the first manufacturing method, and the preferred types are also the same. The polymerization initiator used when initiating polymerization and the polymerization initiator used in each operation of the additional addition operation of polymerization initiator, which is performed two or more times, may be the same or different, and each may be used individually or in combination of two or more types.

[0208] Furthermore, as described above in the first manufacturing method, when an organoalkali metal compound is used as a polymerization initiator, it may be reacted with a secondary amine compound beforehand to be used as an organoalkali metal amide compound. The type of secondary amine compound, the method of adding the organoalkali metal amide compound as a polymerization initiator to the polymerization system, and the amount of secondary amine compound used are not particularly limited and can be the same as in the first manufacturing method for producing low molecular weight conjugated diene polymers.

[0209] The amount of polymerization initiator used to initiate polymerization should be determined according to the molecular weight distribution curve of the target conjugated diene polymer, but it 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.

[0210] The number of times the polymerization initiator is added in the second manufacturing method is not particularly limited as long as it is two or more times, and should be determined according to the molecular weight distribution curve of the target conjugated diene polymer. The amount of polymerization initiator used in the addition operation is not particularly limited, and should be determined according to the molecular weight distribution curve of the target conjugated diene polymer, but it is preferable to use 0.1 to 0.7 moles per mole of polymerization initiator used to start polymerization for each addition operation, and more preferably 0.2 to 0.6 moles. The timing of the addition operation of the polymerization initiator is not particularly limited and should be determined according to the molecular weight distribution curve of the target conjugated diene polymer.

[0211] The polymerization temperature and polymerization method in the second manufacturing method are not particularly limited and may be the same as those used for the polymerization of low molecular weight conjugated diene polymers in the first manufacturing method.

[0212] In the second manufacturing method, similar to the polymerization of low molecular weight conjugated diene polymers in the first manufacturing method, it is preferable to add a polar compound to the inert organic solvent when polymerizing the monomer mixture. The type and amount of polar compound used are not particularly limited and may be the same as for the polymerization of low molecular weight conjugated diene polymers in the first manufacturing method.

[0213] In the second manufacturing method, similar to the polymerization of low molecular weight conjugated diene polymers in the first manufacturing method, a method may be employed in which monomers mainly containing conjugated diene monomers are added to the polymerization system when the polymerization conversion rate is preferably 5% by weight or more, more preferably 10% by weight or more. By employing such a method, segments containing a high proportion of conjugated diene monomers can be introduced to the polymer chain ends. In this case, the weight of conjugated diene monomers added after the start of polymerization relative to the total weight of monomers added after the start of polymerization, the content of conjugated diene monomer units in the segment, and the monomer composition of the segment are not particularly limited and may be the same as in the case of low molecular weight conjugated diene polymers in the first manufacturing method.

[0214] Furthermore, in the second manufacturing method, the conjugated diene polymer may be obtained by a manufacturing method comprising the steps of: polymerizing a monomer (a) containing isoprene in an inert solvent with a polymerization initiator to form a polymer block (A) having an active end, similar to the case of the low molecular weight conjugated diene polymer in the first manufacturing method; and mixing the polymer block (A) having an active end with a monomer (b) containing 1,3-butadiene to continue the polymerization reaction, thereby obtaining polymer block (A) and polymer block (B).

[0215] As described above, a polymer containing polymer chains with active ends can be obtained in an inert solvent.

[0216] A coupling polymer chain may be formed by reacting at least a portion of the polymer chain containing the active end with a coupling agent. This allows for control over the number of peaks in the molecular weight distribution curve of the conjugated diene polymer. The type, amount, and timing of the coupling agent are not particularly limited and can be the same as those for the polymerization of the low molecular weight conjugated diene polymer in the first manufacturing method.

[0217] Furthermore, from the viewpoint of making the effects of the present invention more pronounced, it is preferable to make the conjugated diene polymer have a modified group by reacting a modifying agent with the active ends contained in the polymer chain containing the active ends obtained by polymerization (including the polymer chain containing the active ends after the coupling reaction). The type of modifying agent, the amount of modifying agent used, the reaction conditions, and the timing of adding the modifying agent are not particularly limited and may be the same as those for polymerization of the low molecular weight conjugated diene polymer in the first manufacturing method. In addition, by using a modifying agent that can exert a coupling effect (for example, a polyorganosiloxane), the number of peaks in the molecular weight distribution curve of the conjugated diene polymer can be controlled.

[0218] When using a siloxane compound as a modifier, it is preferable to react the polymer chain having an active end with the siloxane compound and the organometallic compound. The specific aspects, such as the type and amount of organometallic compound used, the reaction method, the timing of adding the organometallic compound, the manner in which the siloxane compound is added, and the timing of adding the siloxane compound, can be the same as those for the polymerization of the low molecular weight conjugated diene polymer in the first production method.

[0219] It is preferable to add a polymerization inhibitor such as methanol, an alcohol such as isopropanol, or water to the polymer chain having active ends obtained by polymerization to deactivate the unreacted active ends. By the above method, a polymer solution of the conjugated diene polymer can be obtained.

[0220] The polymer solution of the conjugated diene polymer obtained by the above method may optionally contain antioxidants and spreading oils, similar to the polymer solution of the low molecular weight conjugated diene polymer in the first production method.

[0221] The conjugated diene polymer obtained in this way can then be separated from the reaction mixture by removing the solvent using any method, such as steam stripping or heating the mixture under reduced pressure, to obtain a solid conjugated diene polymer.

[0222] <Third manufacturing method> The third manufacturing method comprises a first step of polymerizing a monomer mixture containing a conjugated diene compound in an inert solvent in the presence of a polymerization initiator to obtain a solution containing polymer chains having active ends; a second step of forming a coupling polymer chain by performing a coupling reaction on a portion of the polymer chains having active ends obtained in the first step, thereby obtaining a solution containing the polymer chains having active ends and the coupling polymer chains; and a third step of further polymerizing a monomer containing a conjugated diene compound on the polymer chains having active ends after the coupling reaction in the second step, wherein in the first or third step, a polymerization initiator is further added to the polymerization system and polymerization is continued one or more times in which a polymerization additive is added.

[0223] The first step involves polymerizing a monomer containing a conjugated diene compound in an inert solvent in the presence of a polymerization initiator to obtain a solution containing polymer chains having active ends.

[0224] The monomer mixture used in the first step of the third manufacturing method includes at least a conjugated diene monomer. Examples of conjugated diene monomers include those similar to the conjugated diene monomers used to form conjugated diene monomer units described above, and among these, 1,3-butadiene is preferred. In addition to the conjugated diene monomer, the monomer mixture preferably includes the aromatic vinyl monomer described above. Examples of aromatic vinyl monomers include those similar to the aromatic vinyl monomers used to form aromatic vinyl monomer units described above, and among these, styrene is preferred. Furthermore, the monomer mixture may contain a vinyl compound containing a functional group that can interact with silica, but from the viewpoint of further improving the processability of the conjugated diene polymer, it is preferable not to use a vinyl compound containing a functional group that can interact with silica in the first step, but to use it in the third step described later.

[0225] The inert solvent used in the first step is the same as that used in the polymerization of the low molecular weight conjugated diene polymer in the first manufacturing method, and the preferred type and amount used are also the same.

[0226] In the first step, the polymerization initiator used to initiate polymerization and the polymerization initiator used in the subsequent addition of polymerization initiators are the same as those used in the polymerization of low molecular weight conjugated diene polymers in the first production method, and the preferred types and amounts are also the same. Furthermore, as described above in the first production method, when an organoalkali metal compound is used as a polymerization initiator, it may be reacted with a secondary amine compound beforehand to be used as an organoalkali metal amide compound. The type of secondary amine compound, the method of adding the organoalkali metal amide compound as a polymerization initiator to the polymerization system, and the amount of secondary amine compound used are not particularly limited and should be the same as in the polymerization of low molecular weight conjugated diene polymers in the first production method.

[0227] The polymerization temperature and polymerization method in the first step are not particularly limited and may be the same as those used for the polymerization of low molecular weight conjugated diene polymers in the first manufacturing method.

[0228] In the first step, similar to the polymerization of low molecular weight conjugated diene polymers in the first manufacturing method, it is preferable to add a polar compound to the inert organic solvent when polymerizing the monomer mixture. The type and amount of polar compound used are not particularly limited and may be the same as for the polymerization of low molecular weight conjugated diene polymers in the first manufacturing method.

[0229] Furthermore, in the first step, similar to the case of low molecular weight conjugated diene polymers in the first manufacturing method, a solution containing polymer chains with active ends may be obtained by a manufacturing method comprising: a step of polymerizing a monomer (a) containing isoprene in an inert solvent with a polymerization initiator to form a polymer block (A) having active ends; and a step of mixing the polymer block (A) having active ends with a monomer (b) containing 1,3-butadiene to continue the polymerization reaction, thereby obtaining polymer blocks (A) and polymer blocks (B).

[0230] The second step of the third manufacturing method is to perform a coupling reaction on a portion of the polymer chain having an active end obtained in the first step to form a coupling polymer chain, and to obtain a solution containing the polymer chain having an active end and the coupling polymer chain.

[0231] The coupling agent is not particularly limited, and examples of those that can be used in the polymerization of low molecular weight conjugated diene polymers in the first manufacturing method are those mentioned above, and the same applies to preferred ones. The amount of coupling agent used can be determined according to the molecular weight distribution curve of the target conjugated diene polymer, and is not particularly limited, but from the viewpoint of performing the coupling reaction only on a portion of the polymer chain having active ends obtained in the first step, it is preferable to use less than 1 mole of coupling agent in terms of functional groups per mole of polymerization initiator used in the first step, preferably 0.01 to 0.4 moles, and more preferably 0.02 to 0.3 moles. By setting the amount of coupling agent used within the above range, the low fuel consumption characteristics can be further improved. Upon addition of the coupling agent, the polymer chain having active ends undergoes a coupling reaction at the active ends, and as a result, the polymer chain that has undergone the coupling reaction loses its active ends and becomes one that does not have active ends.

[0232] The third step of the third manufacturing method is to further polymerize a monomer containing a conjugated diene compound onto a polymer chain having an active end, after the coupling reaction has been carried out in the second step.

[0233] In the third step, the monomer used for polymerization may contain at least a conjugated diene compound, but from the viewpoint of making the conjugated diene polymer have conjugated diene monomer units and aromatic vinyl monomer units, it is preferable to use a monomer that contains an aromatic vinyl compound. Furthermore, in the third step, it is preferable to use a monomer used for polymerization that contains a vinyl compound containing a functional group that can interact with silica. By using a vinyl compound containing a functional group that can interact with silica in the third step, units of the vinyl compound containing a functional group that can interact with silica can be preferentially introduced into polymer chains other than the polymer chain that underwent the coupling reaction in the second step. As a result, the adsorption rate of the polymer chains other than the polymer chain that underwent the coupling reaction to silica can be effectively increased, and as a result, the low fuel consumption characteristics of the resulting rubber crosslinked product can be further enhanced while maintaining good processability.

[0234] Furthermore, polymerization in the third step may be carried out in an inert solvent, and the inert solvent is not particularly limited; the same solvent as that used in the first step described above can be used. The polymerization temperature and polymerization method are also not particularly limited and may be the same as those used in the first step described above. In addition, the bonding method of each monomer can be various, such as block-like, tapered, and random. Among these, the random bond is preferred. By using a random bond, the low fuel consumption characteristics of the resulting rubber crosslinked product can be further improved.

[0235] Furthermore, in the third manufacturing method, the polymerization initiator is added at one of the following timings: during polymerization in the first step, at the start of polymerization in the third step, or during polymerization in the third step. The timing of adding the polymerization initiator can be determined according to the molecular weight distribution curve of the target conjugated diene polymer, but is not particularly limited. However, it is preferable to add the polymerization initiator at the start of polymerization in the third step or during polymerization in the third step. The amount of polymerization initiator to be added can be determined according to the molecular weight distribution curve of the target conjugated diene polymer, but is not particularly limited. However, it is preferably 0.1 to 0.7 moles, more preferably 0.2 to 0.6 moles, per mole of polymerization initiator used at the start of polymerization.

[0236] Furthermore, it is preferable that the first, second, and third steps described above be carried out in succession. For example, it is preferable that the polymerization reaction in the first step is continued while the coupling reaction by adding the coupling agent in the second step is carried out, followed by the polymerization reaction in the third step.

[0237] Furthermore, after the polymerization reaction in the third step is completed, it is preferable to make the conjugated diene polymer have a modified group by reacting a modifying agent with the active ends contained in the polymer chain. The specific details, such as the type of modifying agent, the amount of modifying agent used, the reaction conditions, and the timing of adding the modifying agent, are not particularly limited and may be the same as those for the polymerization of the low molecular weight conjugated diene polymer in the first manufacturing method. In addition, by using a modifying agent that can exhibit a coupling effect (for example, a polyorganosiloxane), the number of peaks in the molecular weight distribution curve of the conjugated diene polymer can be controlled.

[0238] After the polymerization reaction is complete, a solution of the conjugated diene polymer can be obtained by inactivating the active ends of the polymerization system by adding an alcohol such as methanol, ethanol, or isopropanol, or a polymerization inhibitor such as water, to the polymerization system.

[0239] The polymer solution of the conjugated diene polymer obtained by the above method may optionally contain antioxidants and spreading oils, similar to the polymer solution of the low molecular weight conjugated diene polymer in the first production method.

[0240] The conjugated diene polymer obtained in this way can then be separated from the reaction mixture by removing the solvent using any method, such as steam stripping or heating the mixture under reduced pressure, to obtain a solid conjugated diene polymer.

[0241] The method for producing the conjugated diene polymer of the present invention may be a combination of the above-described methods. For example, the conjugated diene polymer of the present invention may be obtained by appropriately mixing two or more conjugated diene polymers selected from a low molecular weight conjugated diene polymer obtained in the first production method, a high molecular weight conjugated diene polymer obtained in the first production method, a conjugated diene polymer obtained in the second production method, and a conjugated diene polymer obtained in the third production method. When mixing two or more conjugated diene polymers, the two or more conjugated diene polymers may be mixed in polymer solution form or in solid form, but it is preferable to mix the two or more conjugated diene polymers in polymer solution form. That is, it is more preferable to prepare separate solutions containing the two or more conjugated diene polymers to be mixed and then mix each of the prepared solutions.

[0242] <Rubber composition> The rubber composition of the present invention is a composition comprising the conjugated diene polymer of the present invention described above and a filler.

[0243] The rubber composition of the present invention may contain other polymers besides the conjugated diene polymer of the present invention described above. Other polymers include, for example, natural rubber (which may be modified natural rubber such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity 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; it may also 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, excluding the conjugated diene polymers 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 individually or in combination of two or more, such as natural rubber and polybutadiene rubber, or natural rubber and styrene-butadiene copolymer rubber.

[0244] In the rubber composition of the present invention, the conjugated diene polymer of the present invention preferably accounts for 10 to 100% by weight of the polymer component in the rubber composition, and particularly preferably accounts for 50 to 100% by weight. By including the conjugated diene polymer of the present invention in the polymer component in such proportions, a better balance can be achieved between the processability of the rubber composition and the wear resistance and fuel efficiency of the resulting crosslinked rubber.

[0245] 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, with silica being more preferred, because they can further enhance the wear resistance of the resulting crosslinked rubber product. These can be used individually or in combination of two or more.

[0246] 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 mainly consists of hydrated silica, is preferred. Alternatively, a carbon-silica dual-phase filler, in which silica is supported on the surface of carbon black, may be used. These silicas can be used individually or in combination of two or more types. 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 m². 2 / g, more preferably 50-220m 2 / g, particularly preferably 80-170m 2 The concentration is / g. Furthermore, the pH of the silica is preferably 5 to 10.

[0247] Various commercially available silica products can be used as silica. For example, "Hi-Sil210," "Hi-Sil233," and "Hi-Sil243LD" from PPG Industries; "Zeosil 1115MP," "Zeosil 1165MP," and "Zeosil 165GR" from Solvay; "ULTRASIL VN2," "ULTRASIL VN3," "ULTRASIL 7000GR," and "ULTRASIL 9100GR" from EVONIK; and "NIPSIL VN3," "NIPSIL AQ," "NIPSIL ER," and "NIPSIL RS-150" from Tosoh Silica.

[0248] 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. Carbon black can be used individually or in combination of two or more types.

[0249] 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 amount of filler blended within the above range, it is possible to maintain sufficient processability of the rubber composition while further improving the low fuel consumption characteristics and low fuel consumption characteristics of the resulting crosslinked rubber product in a well-balanced manner.

[0250] The rubber composition of the present invention may further contain a silane coupling agent from the viewpoint of further improving the low fuel consumption characteristics of the resulting crosslinked rubber. The silane coupling agent is not particularly limited, and various silane coupling agents can be used, but in the present invention, sulfide-based, mercapto-based, protected mercapto-based (for example, those having a carbonylthio group), thiocyanate-based, vinyl-based, amino-based, methacrylate-based, glycidoxy-based, nitro-based, epoxy-based, or chloro-based silane coupling agents can be suitably used. Specific examples of silane coupling agents include bis(3-(triethoxysilyl)propyl) disulfide, bis(3-triethoxysilylpropyl) trisulfide, bis(3-(triethoxysilyl)propyl) tetrasulfide, γ-mercaptopropyltriethoxysilane, 3-[ Examples include ethoxybis(3,6,9,12,15-pentaoxacosan-1-yloxy)silyl]-1-propanthol, 3-octanoylthio-1-propyl-triethoxysilane, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, γ-trimethoxysilylpropylbenzothiazyltetrasulfide, 3-trimethoxysilylpropylbenzothiazole tetrasulfide, 3-thiocyanatetopropyltriethoxysilane, vinyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, 3-trimethoxysilylpropyl methacrylate monosulfide, γ-glycidoxypropyltriethoxysilane, 3-nitropropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-chloropropyltrimethoxysilane. Additionally, NXT-Z100, NXT-Z30, NXT-Z45, NXT-Z60, NXT-Z45, and NXT from Momentive Performance Materials, and Si69, Si75, and VP Si363 from Evonik DeGussa can also be used. These silane coupling agents can be used individually or in combination of two or more. Alternatively, one or more of these agents may be pre-oligomerized and used in their oligomerized state.The amount of silane coupling agent added is preferably 0.1 to 30 parts by weight, more preferably 1 to 15 parts by weight, per 100 parts by weight of the filler.

[0251] Furthermore, the rubber composition of the present invention preferably further contains a crosslinking agent. Examples of crosslinking agents include sulfur, sulfur-containing compounds such as sulfur halides, organic peroxides, quinone dioximes, organic polyhydric amine compounds, and alkylphenol resins having methylol groups. Among these, sulfur is preferably used. The amount of crosslinking agent is preferably 0.1 to 15 parts by weight, more preferably 0.5 to 5 parts by weight, and particularly preferably 1 to 4 parts by weight, per 100 parts by weight of the polymer component in the rubber composition.

[0252] Furthermore, in addition to the above-mentioned components, the rubber composition of the present invention may contain, in addition to the above-mentioned components, compounding agents such as crosslinking promoters, crosslinking activators, antioxidants, surfactants, process oils, plasticizers, lubricants, and tackifiers in the required amounts according to conventional methods.

[0253] When sulfur or a sulfur-containing compound is used as a 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; thiram-based crosslinking accelerators; dithiocarbamate-based crosslinking accelerators; xanthogenic acid-based crosslinking accelerators; and others. Among these, those containing sulfenamide-based crosslinking accelerators are preferred. These crosslinking accelerators can be used individually or in combination of two or more. The amount of crosslinking accelerator 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 component in the rubber composition.

[0254] Examples of crosslinking activators include higher fatty acids such as stearic acid; zinc oxide; and the like. These crosslinking activators can be used individually 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.

[0255] To obtain the rubber composition of the present invention, each component can be kneaded according to a conventional method. For example, the components, excluding heat-unstable components such as crosslinking agents and crosslinking accelerators, can be kneaded with a conjugated diene polymer, and then the heat-unstable components such as crosslinking agents and crosslinking accelerators can be mixed into the kneaded mixture to obtain the desired composition. The kneading temperature for the components, excluding heat-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. Furthermore, the mixing of the kneaded mixture with the heat-unstable components is usually carried out after cooling to 100°C or below, preferably 80°C or below.

[0256] <Rubber Crosslinked Products> The rubber crosslinked material of the present invention is obtained by crosslinking the rubber composition of the present invention described above.

[0257] The crosslinked rubber product of the present invention can be manufactured by using the rubber composition of the present invention, molding it using a molding machine corresponding to the desired shape, such as an extruder, injection molding machine, compressor, or roll, and then heating it to perform a crosslinking reaction and fix the shape as a crosslinked rubber product. In this case, crosslinking may be performed either after molding or simultaneously with molding. The molding temperature is usually 10 to 200°C, preferably 25 to 120°C. The crosslinking temperature is usually 100 to 200°C, preferably 130 to 190°C, and the crosslinking time is usually 1 minute to 24 hours, preferably 2 minutes to 12 hours, and particularly preferably 3 minutes to 6 hours.

[0258] Furthermore, depending on the shape and size of the crosslinked rubber material, even if the surface is crosslinked, the interior may not be sufficiently crosslinked. In such cases, further heating may be performed to carry out secondary crosslinking.

[0259] For heating, you can appropriately select a common method used for crosslinking rubber, such as press heating, steam heating, oven heating, or hot air heating.

[0260] The crosslinked rubber material 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 efficiency and wear resistance. For this reason, the crosslinked rubber material of the present invention can be used in a variety of applications, such as materials for various parts of a tire, including the cap tread, base tread, carcass, sidewall, and bead; materials for hoses, belts, mats, vibration damping rubber, and other various industrial products; impact resistance modifiers for resins; resin film cushioning agents; shoe soles; rubber shoes; golf balls; toys; and more. In particular, the crosslinked rubber material of the present invention is suitable as a tire material because of its excellent fuel efficiency and wear resistance. [Examples]

[0261] The present invention will be described below based on more detailed examples, but the present invention is not limited to these examples. In each example, "parts" and "%" are based on weight unless otherwise specified. Various measurements and evaluations were performed according to the following methods.

[0262] <Styrene unit content, vinyl bond content> The styrene unit content (weight %) and the amount of vinyl bonded in the conjugated diene monomer unit (mol %) are determined according to JIS K6239 (2007). 1 This was determined by 1H-NMR spectroscopy.

[0263] <Styrene blocking rate> The styrene block rate, as an aromatic vinyl monomer block rate, was measured by 1H-NMR using deuterated chloroform as the solvent, based on the following literature. The peaks from 6.1–7.7 ppm in the obtained 1H-NMR spectrum were considered to be derived from styrene, and of these, 6.1–6.88 ppm were considered to be derived from styrene blocks. The ratio of the peak area derived from styrene blocks to the peak area derived from styrene was calculated, and this value was multiplied by 2.5 and expressed as a percentage to determine the styrene block rate. Reference: Sardelis, K. Michels, HJ Allen, G. Polymer, 1984, 25, 1011

[0264] <Mooney viscosity of conjugated diene polymers> The Mooney viscosity (ML1+4) of the conjugated diene polymer was measured under the following conditions, in accordance with JIS K 6300-1:2013. • Test temperature: 100℃ • Rotor type: L-shaped • Test equipment used: Shimadzu Mooney Viscometer SMV-300J, manufactured by Shimadzu Corporation.

[0265] <Weight-average molecular weight (Mw), molecular weight distribution (Mw / Mn), number of peaks in the molecular weight distribution curve, peak-top molecular weight of each peak> GPC measurements were performed using a styrene column under the following conditions on sample solutions containing a conjugated diene polymer and an internal standard polystyrene. The molecular weight distribution curve of the conjugated diene polymer was obtained by removing the region with a molecular weight of less than 5000 from the obtained molecular weight distribution curve, and further removing the peak of the internal standard polystyrene. Based on the obtained molecular weight distribution curve of the conjugated diene polymer, the weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were determined. The obtained molecular weight distribution curve of the conjugated diene polymer was divided into regions sandwiched by the baseline or minimum value and having one 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 of the conjugated diene polymer is set to 100% was determined as the number of molecular weight peaks. Furthermore, for 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 subsequent peaks were defined as the second peak, third peak, and so on, in order from the region with the lowest molecular weight. Then, the peak-top molecular weight (the molecular weight showing the maximum value in each region) of each peak was determined.

[0266] GPC measurements using styrene columns were performed under the following conditions. (i)GPC equipment Measuring instrument: High-performance liquid chromatograph (manufactured by Tosoh Corporation, product name "HLC-8320") Detector: Differential refractometer Eluent: Tetrahydrofuran (ii) Measurement conditions GPC columns: Tosoh Corporation, product name "GMH-HR-H", 2 columns Mobile phase: 25 mg of 2-(ethylamino)ethanol (Fujifilm Wako Chemical Co., Ltd., special grade) was added to 3 L of tetrahydrofuran (manufactured by Kanto Chemical Co., Ltd., special grade, stabilizer-free). Flow rate: 1mL / min Column oven temperature: 40℃ Detection: Differential refractive index detector (RID) Sample solution injection volume: 50 μL GPC column calibration standard: Polystyrene (manufactured by Agilent Technologies) Thirteen types of standard polystyrene with peak top molecular weights between 100 and 4 million were used. (iii) Sample solution preparation conditions To 20 mL of tetrahydrofuran (manufactured by Kanto Chemical Co., Ltd., special grade, stabilizer-free), 5 mg of standard polystyrene A5000 (manufactured by Tosoh Corporation), with a molecular weight of 5000, was added as an internal standard. Sample solution concentration: 0.5 mg / mL Dissolution conditions: 10 mg of sample and 20 mL of solvent were placed in a screw vial, sealed tightly, and stirred at room temperature for 120 minutes at a stirring speed of 60 strokes / minute using a DF-8020. The mixture was filtered using a syringe fitted with a filtration filter. Filtration filter: Milex-LG, pore size 0.45 μm, hydrophilic, PTFE, filter diameter 25 mm (Merck)

[0267] <Percentage of polymer chains constituting the final detected peak (Z) and maximum peak (L)> The content of polymer chains constituting the final detection peak (Z) and the maximum peak (L) was calculated based on the molecular weight distribution curve of the conjugated diene polymer, obtained in the same manner as the measurement of the peak-top molecular weight of each peak described above. The final detection peak (Z) is the first peak in the measurement of the peak-top molecular weight of each peak described above, and the content of polymer chains constituting the final detection peak (Z) was determined from the ratio of the peak area of ​​the first peak to the peak area of ​​the molecular weight distribution curve of the conjugated diene polymer. Furthermore, among the remaining peaks after removing the first peak from each peak of the molecular weight distribution curve of the conjugated diene polymer, the peak with the largest peak area was identified as the maximum peak (L). The content of polymer chains constituting the maximum peak (L) was determined from the ratio of the peak area of ​​the maximum peak (L) to the peak area of ​​the molecular weight distribution curve of the conjugated diene polymer.

[0268] <Adsorption rate of polymer chains constituting the maximum peak (L) to silica> Similar to the measurement of the content of polymer chains constituting the maximum peak (L) described above, the maximum peak (L) was identified in the molecular weight distribution curve of the conjugated diene polymer, and the molecular weight range representing the polymer chain constituting the maximum peak (L) was determined. The adsorption rate of the polymer chain constituting the maximum peak (L) to silica was calculated based on the following formula (I) by performing GPC measurements using a styrene column and a silica column on a sample solution containing the conjugated diene polymer and internal standard polystyrene. Adsorption rate (%) of the polymer chain constituting the maximum peak (L) to silica = [1 - (P2 × P3) / (P1 × P4)] × 100 (I) P1: Peak area of ​​the polymer chain constituting the maximum peak (L), as measured by GPC using a styrene-based column. P2: Peak area of ​​the internal standard polystyrene peak measured by GPC using a styrene-based column. P3: Peak area of ​​the polymer chain peak constituting the maximum peak (L), as determined by GPC measurement using a silica column. P4: Peak area of ​​the internal standard polystyrene peak measured by GPC using a silica column.

[0269] GPC measurement using a styrene-based column follows the same conditions as the weight-average molecular weight (Mw) measurement described above.

[0270] GPC measurements using silica columns were performed in the same manner as GPC measurements using styrene columns, except that silica columns (columns: Zorbax PSM-1000S, PSM-1000S, PSM-60S connected in series, oven temperature 40°C, THF flow rate 0.6 mL / min) were used instead of styrene columns.

[0271] <Workability> The Mooney viscosity (ML1+4) of the rubber composition was measured under the following conditions in accordance with JIS K 6300-1:2013. An index was calculated for the obtained Mooney viscosity (ML1+4), with the Mooney viscosity (ML1+4) of Comparative Example 5 set to 100, and this index was used as the processability value. A higher processability value indicates superior processability of the conjugated diene polymer. • Test temperature: 100℃ • Rotor type: L-shaped • Test equipment used: Shimadzu Mooney Viscometer SMV-300J, manufactured by Shimadzu Corporation.

[0272] <Strength Characteristics> Using a crosslinked rubber sheet, the tensile strength (MPa) and elongation (%) at fracture were measured under the following conditions in accordance with JIS K6251:2010, and the product of tensile strength and elongation was calculated. An index was calculated for the obtained product of tensile strength and elongation, with the product of tensile strength and elongation in Comparative Example 5 set to 100, and this index was used as the strength characteristic value. A larger strength characteristic value indicates superior strength properties of the resulting crosslinked rubber. • Specimen preparation method: Sheets are prepared by press crosslinking, followed by punching. • Test specimen shape: Dumbbell-shaped, type 3 • Specimen sampling direction: Parallel to the grain • Number of test specimens: 3 ·Measurement temperature: 23℃ • Test speed: 500 mm / min • Test equipment used: ALPHA TECHNOLOGIES TENSOMETER 10k • Test machine capacity: Load cell type 1kN

[0273] <Wear resistance properties> Test specimens were obtained by molding rubber crosslinked sheets to an outer diameter of 50 mm, an inner diameter of 15 mm, and a thickness of 10 mm. The wear resistance of the obtained test specimens was measured using an FPS wear tester manufactured by Ueshima Seisakusho Co., Ltd., under conditions of a load of 1 kgf and a slip ratio of 5%. For the wear resistance of each example and comparative example, an index was calculated with the wear resistance of Comparative Example 5 set to 100, and this was used as the value of the wear resistance characteristic. A higher value of the wear resistance characteristic indicates that the resulting rubber crosslinked material has superior wear resistance.

[0274] <Fuel efficiency characteristics> A rubber crosslinked sheet was punched out into strips 2 mm thick and 40 mm long to obtain test specimens. The loss tangent (tanδ(60°C)) of the obtained test specimens was measured using a viscoelasticity measuring device (manufactured by Ueshima Seisakusho Co., Ltd.) under the conditions of a frequency of 10 Hz, initial elongation of 10%, strain amplitude of 2%, and temperature of 60°C. For the loss tangent (tanδ(60°C)) in each example and comparative example, an index was calculated with the loss tangent (tanδ(60°C)) in Comparative Example 5 set to 100, and this was used as the value for low fuel consumption characteristics. A larger value for low fuel consumption characteristics indicates that the resulting rubber crosslinked material has superior low fuel consumption characteristics.

[0275] <Preparation of polymer block (A) with active ends> 140.8 g of cyclohexane and 3.0 mmol of tetramethylethylenediamine were added to an 800 ml nitrogen-purged container, followed by the addition of 30.0 mmol of n-butyllithium. Then, 113.6 g of isoprene and 9.2 g of styrene were slowly added, and the mixture was reacted in a container at 50°C for 120 minutes to obtain a polymer block (A) with active ends. The obtained 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% by weight, an isoprene monomer unit content of 92.5% by weight, and a vinyl bond content of 7.0 mol%.

[0276] <Manufacturing Example 1> In a 20L autoclave equipped with a stirrer, 7956g of industrial hexane (Sumitomo Chemical Co., Ltd., trade name: Hexane (general product), density 0.68g / mL), 1014g of cyclohexane, 3.08mmol of tetramethylethylenediamine, 425g of 1,3-butadiene, 680g of styrene, and 4.27mmol of piperidine were charged under a nitrogen atmosphere. To pre-detoxify impurities that could deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 4.27mmol of n-butyllithium, and polymerization was started at 55°C. After continuing the polymerization reaction for 15 minutes, 595g of 1,3-butadiene was continuously added over 85 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, a polyorganosiloxane represented by formula (13) below was added 10 minutes later to a concentration of 3.42 mmol of epoxy groups, and the mixture was reacted for 20 minutes. Subsequently, as a polymerization inhibitor, 2 equivalents of methanol relative to the total amount of lithium in the autoclave were added to obtain a solution containing the conjugated diene polymer. To this solution, 0.20 parts of 2,4-bis(octylthiomethyl)-6-methylphenol (RIANOX, trade name: RIANOX1520) was added as an antioxidant to 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0277] [ka]

[0278] <Manufacturing Example 2> In a 20 L autoclave equipped with a stirrer, 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 were charged under a nitrogen atmosphere. To pre-detoxify impurities that could deactivate 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 ends obtained above was added (calculated in terms of lithium atom content), and the polymerization growth reaction was carried out at 55°C. After continuing the polymerization reaction for 15 minutes, 595 g of 1,3-butadiene was continuously added over 85 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 1.2 mmol of n-butyllithium was added, and after another 10 minutes, the polyorganosiloxane represented by 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, as a polymerization inhibitor, 2 equivalents of methanol relative to the total amount of lithium in the autoclave were added to obtain a solution containing the conjugated diene polymer. To this solution, 0.20 parts of 2,4-bis(octylthiomethyl)-6-methylphenol was added as an antioxidant for every 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0279] <Manufacturing Example 3> In a 20 L autoclave equipped with a stirrer, 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 were charged under a nitrogen atmosphere. To pre-detoxify impurities that would deactivate 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 ends obtained above was added (calculated in terms of lithium atom content), and the polymerization growth reaction was carried out at 55°C. After continuing the polymerization reaction for 15 minutes, 0.86 g of bis(diethylamino)methylvinylsilane was added, and 700 g of 1,3-butadiene was continuously added over 75 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by formula (13) was added 10 minutes later so that the epoxy group content was 12 mmol, and the mixture was reacted for 20 minutes. Then, as a polymerization inhibitor, 2 equivalents of methanol relative to the total amount of lithium in the autoclave were added to obtain a solution containing the conjugated diene polymer. To this solution, 0.20 parts of 2,4-bis(octylthiomethyl)-6-methylphenol was added as an antioxidant for every 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0280] <Manufacturing Example 4> The polymer solution was obtained by performing the same procedure as in Production Example 2, except that the amount of tetramethylethylenediamine was changed to 2.62 mmol and the amount of polymer block (A) was changed to 4.86 mmol when converted to lithium atom content.

[0281] <Manufacturing Example 5> In a 20 L autoclave equipped with a stirrer, 7956 g of industrial hexane, 1014 g of cyclohexane, 3.2 mmol of tetramethylethylenediamine, 510 g of 1,3-butadiene, and 680 g of styrene were charged under a nitrogen atmosphere. To pre-detoxify impurities that could deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 4.05 mmol of n-butyllithium, and polymerization was started at 55°C. After continuing the polymerization reaction for 15 minutes, 510 g of 1,3-butadiene was continuously added over 85 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.12 mmol of 1,6-bis(trichlorosilyl)hexane was added, and after another 10 minutes, the polyorganosiloxane represented by formula (13) above was added so that the epoxy group content was 1.21 mmol, and the reaction was allowed to proceed for 20 minutes. Subsequently, methanol in an amount of 2 equivalents relative to the total amount of lithium in the autoclave was added as a polymerization inhibitor to obtain a solution containing the conjugated diene polymer. To this solution, 0.15 parts of 2,4-bis(octylthiomethyl)-6-methylphenol was added as an antioxidant per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0282] <Manufacturing Example 6> In a 20 L autoclave with a stirrer, 7072 g of industrial hexane, 2028 g of cyclohexane, 4.0 mmol of tetramethylethylenediamine, 431 g of 1,3-butadiene, 718 g of styrene, and 1.05 g of bis(diethylamino)methylvinylsilane were charged under a nitrogen atmosphere. To pre-detoxify impurities that could deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 7.29 mmol of n-butyllithium, and polymerization was started at 40°C. Immediately after the start of polymerization, 719 g of 1,3-butadiene was added continuously over 130 minutes, and 48 g of styrene was added continuously over 90 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.66 mmol of silicon tetrachloride was added, and after another 15 minutes, 26.52 mmol of N-(3-dimethylaminopropyl)acrylamide was added, and the reaction was allowed to proceed for 10 minutes. Subsequently, 73.6 mmol of n-butyllithium was added, and after 15 minutes, 2 equivalents of methanol relative to the total amount of lithium in the autoclave were added as a polymerization inhibitor to obtain a solution containing the conjugated diene polymer. To this solution, 0.75 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.

[0283] <Manufacturing Example 7> In a 20L autoclave equipped with a stirrer, 8160g of industrial hexane, 2340g of cyclohexane, 1.9 mmol of tetramethylethylenediamine, 400g of 1,3-butadiene, and 600g of styrene were charged under a nitrogen atmosphere. To pre-detoxify impurities that could deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 2.27 mmol of n-butyllithium, and polymerization was started at 45°C. After continuing the polymerization reaction for 30 minutes, 500g of 1,3-butadiene was continuously added over 150 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 3.40 mmol of 3-(diethylamino)propyltrimethoxysilane was added, and after another 20 minutes, 5.10 mmol of n-butyllithium was added, and the reaction was allowed to continue for 20 minutes. Subsequently, two equivalents of methanol were added to the total amount of lithium in the autoclave as a polymerization inhibitor to obtain a solution containing the conjugated diene polymer. To this solution, 0.40 parts and 0.20 parts, respectively, of 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumirizer GM) and pentaerythrityltetrakis(3-laurylthiopropionate) (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumirizer TP-D) were added per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0284] <Manufacturing Example 8> In a 20L autoclave equipped with a stirrer, 8160g of industrial hexane, 2340g of cyclohexane, 3.1 mmol of tetramethylethylenediamine, 492g of 1,3-butadiene, and 600g of styrene were charged under a nitrogen atmosphere. To pre-detoxify impurities that could deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 15.0 mmol of n-butyllithium, and polymerization was started at 45°C. After continuing the polymerization reaction for 15 minutes, 408g of 1,3-butadiene was continuously added over 80 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 22.50 mmol of 3-(diethylamino)propyltrimethoxysilane was added, and after another 20 minutes, 33.75 mmol of n-butyllithium was added and the reaction was allowed to continue for 20 minutes. Subsequently, two equivalents of methanol were added to the total amount of lithium in the autoclave as a polymerization inhibitor to obtain a solution containing the conjugated diene polymer. To this solution, 0.40 parts and 0.20 parts of 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and pentaerythrityltetrakis(3-laurylthiopropionate) were added as antioxidants, respectively, per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0285] <Manufacturing Example 9> After confirming that the polymerization conversion rate was in the range of 95% to 100%, the polymer solution was obtained by performing the same procedure as in Production Example 2, except that n-butyllithium and the polyorganosiloxane represented by formula (13) above were not added.

[0286] <Manufacturing Example 10> After confirming that the polymerization conversion rate was in the range of 95% to 100%, the polymer solution was obtained by performing the same procedure as in Production Example 3, except that the polyorganosiloxane represented by formula (13) above was not added.

[0287] <Manufacturing Example 11> A polymer solution was obtained by following the same procedure as in Production Example 1, except that piperidine was not used, and instead of the polyorganosiloxane represented by formula (13) above, 0.34 mmol of silicon tetrachloride was added, and 5.81 mmol of 3-(diethylamino)propyltrimethoxysilane was added 10 minutes after the addition of silicon tetrachloride and reacted for 20 minutes.

[0288] <Manufacturing Example 12> A polymer solution was obtained by performing the same procedure as in Production Example 3, except that the amount of tetramethylethylenediamine used was changed to 2.94 mmol, the amount of polymer block (A) used was changed from 20.0 mmol to 58.8 mmol when converted to lithium atom content, and the amount of polyorganosiloxane represented by the above formula (13) was changed to 35.3 mmol.

[0289] <Manufacturing Example 13> A polymer solution was obtained by performing the same procedure as in Production Example 3, except that the amount of tetramethylethylenediamine used was changed to 5.0 mmol, the amount of polymer block (A) used was changed from 20.0 mmol to 13.16 mmol in terms of lithium atom content, and the amount of polyorganosiloxane represented by the above formula (13) was changed to 7.89 mmol.

[0290] <Manufacturing Example 14> A polymer solution was obtained by performing the same procedure as in Production Example 2, except that the amount of tetramethylethylenediamine used was changed from 7.2 mmol to 3.83 mmol, the amount of polymer block (A) used was changed from 20.0 mmol to 7.66 mmol when converted to lithium atom content, and the amount of polyorganosiloxane represented by the above formula (13) was changed to 5.36 mmol.

[0291] <Manufacturing Example 15> In a 20 L autoclave equipped with a stirrer, 8160 g of industrial hexane, 2340 g of cyclohexane, 4.6 mmol of tetramethylethylenediamine, 550 g of 1,3-butadiene, 130 g of styrene, and 2.39 mmol of piperidine were charged under a nitrogen atmosphere. To pre-detoxify impurities that would deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 3.41 mmol of n-butyllithium, and polymerization was started at 40°C. Immediately after the start of polymerization, 616 g of 1,3-butadiene was continuously added over 180 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by formula (13) above was added so that the epoxy group content was 1.21 mmol, and the reaction was allowed to proceed for 20 minutes. Subsequently, 2 equivalents of methanol relative to the total amount of lithium in the autoclave were added as a polymerization termination agent to obtain a solution containing the conjugated diene polymer. To this solution, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and pentaerythrityltetrakis(3-laurylthiopropionate) were added as anti-aging agents at a rate of 0.40 parts and 0.20 parts, respectively, per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0292] <Manufacturing Example 16> In a 20 L autoclave with a stirrer, under a nitrogen atmosphere, 8160 g of industrial hexane, 2340 g of cyclohexane, 8.0 mmol of tetramethylethylenediamine, 550 g of 1,3-butadiene, 130 g of styrene, 1.11 g of bis(diethylamino)methylvinylsilane, and 7.2 mmol of piperidine were charged. To pre-detoxify impurities that could deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 14.4 mmol of n-butyllithium, and polymerization was started at 40°C. Immediately after the start of polymerization, 616 g of 1,3-butadiene was continuously added over 140 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by formula (13) above was added so that the epoxy group content was 8.64 mmol, and the reaction was allowed to proceed for 20 minutes. Subsequently, two equivalents of methanol were added to the total amount of lithium in the autoclave as a polymerization inhibitor to obtain a solution containing the conjugated diene polymer. To this solution, 0.40 parts and 0.20 parts of 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and pentaerythrityltetrakis(3-laurylthiopropionate) were added as antioxidants, respectively, per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0293] <Manufacturing Example 17> A polymer solution was obtained by following the same procedure as in Production Example 15, except that piperidine was not used, and instead of n-butyllithium, 3.41 mmol of the polymer block (A) having the active end obtained above was added in terms of lithium atom content and the polymerization growth reaction was carried out, and instead of the polyorganosiloxane represented by formula (13) above, 0.17 mmol of silicon tetrachloride was added, and 20 minutes after the addition of silicon tetrachloride, 2.05 mmol of N-phenyl-2-pyrrolidone was added and reacted for 20 minutes.

[0294] <Manufacturing Example 18> A polymer solution was obtained by following the same procedure as in Production Example 16, except that bis(diethylamino)methylvinylsilane and piperidine were not used, and the polyorganosiloxane represented by formula (13) was not added after confirming that the polymerization conversion rate was in the range of 95% to 100%.

[0295] <Manufacturing Example 19> A polymer solution was obtained by following the same procedure as in Production Example 15, except that piperidine was not used, the amount of tetramethylethylenediamine used was changed from 4.6 mmol to 4.2 mmol, the amount of n-butyllithium used was changed from 3.41 mmol to 2.16 mmol, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by formula (13) above was not added.

[0296] <Manufacturing Example 20> A polymer solution was obtained by following the same procedure as in Production Example 16, except that bis(diethylamino)methylvinylsilane and piperidine were not used, and instead of n-butyllithium, 14.4 mmol of the polymer block (A) having the active end obtained above was added in terms of lithium atom content and the polymerization growth reaction was carried out, and instead of the polyorganosiloxane represented by formula (13) above, 14.4 mmol of N-(3-dimethylaminopropyl)acrylamide was added and reacted for 20 minutes.

[0297] <Manufacturing Example 21> A polymer solution was obtained by following the same procedure as in Production Example 16, except that piperidine was not used, the amount of tetramethylethylenediamine used was changed from 8.0 mmol to 5.5 mmol, the amount of n-butyllithium used was changed from 14.4 mmol to 6.48 mmol, and 3.24 mmol of 3-(2-aminoethylamino)propyltrimethoxysilane was added 20 minutes after the addition of the polyorganosiloxane represented by formula (13) above, and the reaction was carried out for 20 minutes.

[0298] <Manufacturing Example 22> In a 20L autoclave equipped with a stirrer, 8160g of industrial hexane, 2340g of cyclohexane, 3.09 mmol of tetramethylethylenediamine, 567g of 1,3-butadiene, and 243g of styrene were charged under a nitrogen atmosphere. To pre-detoxify impurities that could deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 3.18 mmol of n-butyllithium, and polymerization was started at 45°C. After continuing the polymerization reaction for 20 minutes, 810g of 1,3-butadiene was continuously added over 150 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 4.78 mmol of 3-(diethylamino)propyltrimethoxysilane was added, and after another 20 minutes, 7.16 mmol of n-butyllithium was added and the reaction was allowed to continue for 20 minutes. Subsequently, two equivalents of methanol were added to the total amount of lithium in the autoclave as a polymerization inhibitor to obtain a solution containing the conjugated diene polymer. To this solution, 0.40 parts and 0.20 parts of 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and pentaerythrityltetrakis(3-laurylthiopropionate) were added as antioxidants, respectively, per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0299] <Manufacturing Example 23> In a 20L autoclave equipped with a stirrer, 8160g of industrial hexane, 2340g of cyclohexane, 5.95 mmol of tetramethylethylenediamine, 475g of 1,3-butadiene, and 243g of styrene were charged under a nitrogen atmosphere. To pre-detoxify impurities that could deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 17.5 mmol of n-butyllithium, and polymerization was started at 45°C. After continuing the polymerization reaction for 10 minutes, 902g of 1,3-butadiene was continuously added over 80 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 26.25 mmol of 3-(diethylamino)propyltrimethoxysilane was added, and after another 20 minutes, 39.38 mmol of n-butyllithium was added and the reaction was allowed to continue for 20 minutes. Subsequently, two equivalents of methanol were added to the total amount of lithium in the autoclave as a polymerization inhibitor to obtain a solution containing the conjugated diene polymer. To this solution, 0.40 parts and 0.20 parts of 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and pentaerythrityltetrakis(3-laurylthiopropionate) were added as antioxidants, respectively, per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0300] <Manufacturing Example 24> In a 20L autoclave equipped with a stirrer, 8160g of industrial hexane, 2340g of cyclohexane, 96mmol of tetrahydrofuran, 5.33mmol of ethylene glycol diethyl ether, 921g of 1,3-butadiene, 163g of styrene, and 0.40g of bis(diethylamino)methylvinylsilane were charged under a nitrogen atmosphere. To pre-detoxify impurities that could deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 14.3mmol of n-butyllithium, and polymerization was started at 40°C. Immediately after the start of polymerization, 1030g of 1,3-butadiene was added continuously over 115 minutes, and 54g of styrene was added continuously over 80 minutes. 15 minutes after the start of polymerization, 0.52g of bis(diethylamino)methylvinylsilane was added. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.79 mmol of silicon tetrachloride was added and reacted for 10 minutes, then 14.3 mmol of 3-(diethylamino)propyltrimethoxysilane was added and reacted for 20 minutes. Subsequently, 28.53 mmol of n-butyllithium was added, and after another 15 minutes, 13.76 mmol of N-(3-dimethylaminopropyl)acrylamide was added and reacted for 15 minutes. Then, as a polymerization inhibitor, 1.5 equivalents of methanol relative to the total amount of lithium in the autoclave was added to obtain a solution containing the conjugated diene polymer. To this solution, 0.56 parts of 2,4-bis(octylthiomethyl)-6-methylphenol was added as an antioxidant per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0301] <Manufacturing Example 25> In a 20 L autoclave equipped with a stirrer, 8160 g of industrial hexane, 2340 g of cyclohexane, 99 mmol of tetrahydrofuran, 9.60 mmol of ethylene glycol dibutyl ether, 689 g of 1,3-butadiene, 162 g of styrene, and 2.27 mmol of piperidine were charged under a nitrogen atmosphere. To pre-detoxify impurities that would deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger, followed by the addition of 3.24 mmol of n-butyllithium, and polymerization was started at 40°C. Immediately after the start of polymerization, 769 g of 1,3-butadiene was continuously added over 195 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 4.86 mmol of 3-(diethylamino)propyltrimethoxysilane was reacted for 20 minutes. Subsequently, two equivalents of methanol relative to the total amount of lithium in the autoclave were added as a polymerization termination agent to obtain a solution containing a conjugated diene polymer. To this solution, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and pentaerythrityltetrakis(3-laurylthiopropionate) were added as anti-aging agents at a rate of 0.40 parts and 0.20 parts, respectively, per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0302] <Manufacturing Example 26> In a 20L autoclave equipped with a stirrer, 8160g of industrial hexane, 2340g of cyclohexane, 99mmol of tetrahydrofuran, 7.50mmol of ethylene glycol dibutyl ether, 550g of 1,3-butadiene, 130g of styrene, and 51.4g of isoprene were charged under a nitrogen atmosphere. To pre-detoxify impurities that would deactivate polymerization, a small amount of n-butyllithium was added to the autoclave as a scavenger. Then, 18.71mmol of n-butyllithium was added, followed by the addition of 18.71mmol of the polymer block (A) with active ends obtained above, calculated in terms of lithium atom content. The polymerization growth reaction was carried out at 40°C. Subsequently, 616g of 1,3-butadiene was continuously added over 100 minutes. After confirming that the polymerization conversion rate was in the range of 95% to 100%, 1.12 mmol of silicon tetrachloride was added, and after another 10 minutes, 14.97 mmol of N-phenyl-2-pyrrolidone was added and the mixture was reacted for 50 minutes. Subsequently, two equivalents of methanol relative to the total amount of lithium in the autoclave were added as a polymerization inhibitor to obtain a solution containing the conjugated diene polymer. To this solution, 0.40 parts and 0.20 parts of 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate and pentaerythrityltetrakis(3-laurylthiopropionate) were added as antioxidants, respectively, per 100 parts of the conjugated diene polymer to obtain a polymer solution.

[0303] For each polymer solution obtained in Production Examples 1 to 26, the styrene unit content, vinyl bond content, styrene block rate, weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) were measured according to the method described above. The results are shown in Table 1.

[0304] [Table 1]

[0305] [Examples 1-8 and Comparative Examples 1-12] In each polymer solution obtained in Production Examples 1-26, the ratio of the mass of each conjugated diene polymer to the mass of oil (manufactured by Nippon Oil Corporation, trade name "Aromax T-DAE") was as shown in Tables 2 and 3. The polymer solution and oil were mixed and stirred until homogeneous, then the solvent was removed by steam stripping, and the mixture was dried for 24 hours in a vacuum dryer set to 60°C to obtain the conjugated diene polymer. For the obtained conjugated diene polymer, the styrene unit content, vinyl bond content, styrene block rate, Mooney viscosity, weight-average molecular weight (Mw), molecular weight distribution (Mw / Mn), number of peaks in the molecular weight distribution curve, peak-top molecular weight of each peak, final detection peak (Z), content ratio of polymer chains constituting the maximum peak (L), and adsorption rate of polymer chains constituting the maximum peak (L) to silica were measured and evaluated according to the method described above. The results are shown in Tables 2 and 3.

[0306] [Table 2]

[0307] [Table 3]

[0308] In a 250ml Bravender-type mixer, the conjugated diene rubbers of Examples 1-8 and Comparative Examples 1-12 shown in Tables 2 and 3 were kneaded for 30 seconds in the amounts shown in Tables 4 and 5 (including the amount of oil if the polymer solution and oil were mixed as described above). Then, silica (manufactured by Evonik, trade name "ULTRASIL® 7000GR"), carbon black (N339), and process oil (manufactured by Nippon Oil Corporation, trade name "Aromax") were added in the proportions (parts by mass) shown in Tables 4 and 5. T-DAE, a silane coupling agent: bis(3-(triethoxysilyl)propyl) disulfide (manufactured by Degussa, trade name "Si75"), zinc oxide, stearic acid, and an antioxidant: N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (manufactured by Ouchi Shinko Co., Ltd., trade name "Nocrac 6C") were added, and the mixture was kneaded for a further 3.5 minutes before being discharged from the mixer. The temperature of the mixture at the end of kneading was 140°C. Next, in an open roll at 50°C, sulfur, crosslinking accelerator: N-tert-butyl-2-benzothiazolyl sulfenamide (vulcanization accelerator (1); trade name "Noxellar NS-P", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.), and diphenylguanidine (vulcanization accelerator (2); trade name "Noxellar D", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) were added to the resulting mixture in the proportions (parts by mass) shown in Tables 4 and 5, and then kneaded together. After that, a sheet-like rubber composition was taken out. The processability of the obtained rubber composition was evaluated. The results are shown in Tables 4 and 5.

[0309] The obtained rubber composition was press-crosslinked at 160°C for 30 minutes to prepare test specimens of crosslinked rubber. The strength properties, abrasion resistance, and fuel efficiency properties of these test specimens were evaluated according to the method described above. The results are shown in Tables 4 and 5.

[0310] [Table 4]

[0311] [Table 5]

[0312] From Tables 2, 3, 4, and 5, the following points can be confirmed. In other words, conjugated diene polymers that have three or more peaks in the molecular weight distribution curve obtained by GPC measurement, a peak-top molecular weight of the final detected peak (Z) between 80,000 and 250,000, and an adsorption rate of less than 40% of the polymer chain constituting the maximum peak (L) to silica, can provide rubber crosslinked materials with excellent processability and superior strength, wear resistance, and fuel efficiency (Examples 1-8). On the other hand, when the number of peaks in the molecular weight distribution curve obtained by GPC measurement was less than 3, or when the peak top molecular weight of the final detected peak (Z) was less than 80,000 or more than 250,000, or when the adsorption rate of the polymer chain constituting the maximum peak (L) to silica was 40% or more, the conjugated diene polymer had a poor balance of processability, strength properties, wear resistance properties, and low fuel consumption properties of the resulting rubber crosslinked product (Comparative Examples 1-12).

Claims

1. A conjugated diene polymer containing at least conjugated diene monomer units, The number of peaks in the molecular weight distribution curve obtained by gel permeation chromatography is three or more. In the molecular weight distribution curve, there is at least a final detection peak (Z), which is the peak detected latest during gel permeation chromatography measurement; a maximum peak (L), which is the peak with the largest peak area among the remaining peaks excluding the final detection peak (Z); and a peak having a peak top molecular weight greater than the peak top molecular weight of the maximum peak (L). The peak top molecular weight of the final detection peak (Z) is between 130,000 and 250,000. A conjugated diene polymer in which the adsorption rate of the polymer chain constituting the maximum peak (L) to silica is less than 40%.

2. The conjugated diene polymer according to claim 1, wherein the peak top molecular weight of the maximum peak (L) is greater than 600,000.

3. A conjugated diene polymer according to claim 1 or 2, containing a terminally modified group.

4. A conjugated diene polymer according to any one of claims 1 to 3, comprising a coupling polymer chain.

5. A rubber composition comprising a conjugated diene polymer according to any one of claims 1 to 4 and a filler.

6. A crosslinked rubber product obtained by crosslinking the rubber composition described in claim 5.

7. A tire comprising the rubber crosslinking material described in claim 6.

8. A method for producing a conjugated diene polymer according to any one of claims 1 to 4, A method for producing a conjugated diene polymer, comprising the step of mixing two or more conjugated diene polymers having different molecular weight distribution curves in a polymer solution.

9. A method for producing a conjugated diene polymer according to any one of claims 1 to 4, A method for producing a conjugated diene polymer, comprising the steps of starting the polymerization of a monomer mixture containing a conjugated diene monomer using a polymerization initiator, and then adding a polymerization initiator to the polymerization system to continue the polymerization.

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