Conjugated diene polymer and method for producing conjugated diene polymer

Abstract

Provided is a conjugated diene polymer having two or more polymer segments, in which: the absolute value (X1-X2) of the difference between the amount of aromatic vinyl monomer units bonded to a first polymer segment (X1 (mass%)) and the amount of aromatic vinyl monomer units bonded to a second polymer segment (X2 (mass%)) is 5 mass% or less; the difference (Y2-Y1) between the amount of vinyl bonds (Y1 (mol%)) in the conjugated diene bonded to the first polymer segment and the amount of vinyl bonds (Y2 (mol%)) in the conjugated diene bonded to the second polymer segment is 15-50 mol%, inclusive, and the estimated glass transition temperature (estimated Tg) of the conjugated diene polymer is-72 DEG C to-40 DEG C, inclusive.

Description

Technical Field

[0001] The present invention relates to a conjugated diene polymer and a method for producing the conjugated diene polymer. Background Art

[0002] One of the fundamental functions required of automotive tire treads is braking performance on the road. Recent climate change has led to sudden rains making roads slippery, while sudden snowfalls have also transformed roads into icy and snowy surfaces. In these environments, tires are required to provide excellent braking performance not only on dry roads but also on icy, snowy, and wet surfaces. Furthermore, since tires that meet these requirements eliminate the need for seasonal tire replacement, consumer demand is increasing.

[0003] Generally, wet grip performance is a required characteristic of tire tread rubber for braking on slippery roads, while winter performance is a required characteristic for braking on ice and snow. These two properties are mutually exclusive. In other words, improving one tends to deteriorate the other. Therefore, tire tread rubber is required to eliminate these conflicting characteristics.

[0004] Furthermore, due to stricter fuel efficiency regulations for automobiles, there is a growing demand for resin-based automotive components and thinner tires to reduce vehicle weight. This thinning of tires requires a particularly thinner tread, which makes up a significant portion of the tire's overall surface and comes into contact with the road. This has led to a greater demand for rubber materials with superior wear resistance.

[0005] On the other hand, from the perspective of tire durability, rubber materials also require tensile properties. As mentioned above, when using multiple rubbers to improve both wet grip performance and winter performance, low mutual affinity between these multiple rubbers tends to reduce the mechanical strength of the rubber material. Therefore, rubber materials that can meet these properties are required.

[0006] As a rubber material that meets the requirements for improvement of various properties as described above, for example, a rubber composition containing a rubber-like polymer and a reinforcing filler such as carbon black and silica is known.

[0007] In such rubber compositions, attempts have been made to improve various properties such as filler dispersibility and wear resistance by introducing functional groups having affinity or reactivity with fillers into the molecular terminals of highly mobile rubber polymers.

[0008] For example, Patent Documents 1 to 3 disclose rubber compositions containing a modified conjugated diene polymer and silica, wherein the modified conjugated diene polymer is obtained by reacting an amino group-containing alkoxysilane with the active end of the conjugated diene polymer. Furthermore, Patent Document 4 discloses a rubber composition containing a modified conjugated diene polymer having a low vinyl group. Furthermore, Patent Document 5 discloses a rubber composition containing a conjugated diene polymer composition in which a plurality of modified conjugated diene polymers are mixed.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-290355

[0012] Patent Document 2: Japanese Patent Application Laid-Open No. 11-189616

[0013] Patent Document 3: Japanese Patent Application Laid-Open No. 2003-171418

[0014] Patent Document 4: Japanese Patent No. 6512240

[0015] Patent Document 5: Japanese Patent Application Laid-Open No. 2021-143324 Summary of the Invention

[0016] Problems to be solved by the invention

[0017] However, conventionally known rubber compositions, such as those disclosed in Patent Documents 1 to 4, have physical properties that still require improvement. For example, existing rubber compositions containing conjugated diene polymers suffer from the following problem: Improved wet grip performance results in reduced winter performance and deterioration on ice and snow, making it difficult to achieve both. Furthermore, when such rubber compositions are vulcanized, particularly when formulated as sulfides containing inorganic fillers such as silica, the dispersibility of the silica decreases, resulting in poor flexibility, which not only reduces performance on ice and snow but also leads to insufficient wear resistance.

[0018] Furthermore, detailed studies of the rubber composition described in Patent Document 5 revealed the following problem: while it is suitable for designing tires for applications requiring wet grip performance, such as summer tires, its winter performance for all-season applications, such as those aimed at use in lower temperature environments, still requires improvement.

[0019] Therefore, an object of the present invention is to provide a conjugated diene polymer and a method for producing the conjugated diene polymer, which can provide a rubber composition having excellent wet grip performance, winter performance, wear resistance, and tensile properties.

[0020] Means for solving problems

[0021] The present inventors have conducted intensive studies to solve the above-mentioned problems and, as a result, have discovered that by setting the absolute value of the difference in the amount of bonded aromatic vinyl monomer units and the difference in the amount of vinyl bonds in the plurality of polymer segments constituting a conjugated diene-based polymer within a predetermined numerical range, and setting the glass transition temperature (estimated Tg) estimated from the microstructure of the conjugated diene-based polymer within a predetermined numerical range, a rubber composition can be obtained that achieves both wet grip performance and winter performance, and also exhibits excellent wear resistance and tensile properties. This has led to the completion of the present invention.

[0022] That is, the present invention is as follows. [1]

[0024] A conjugated diene polymer having two or more polymer segments, wherein:

[0025] The absolute value of the difference between the amount X1 (mass %) of the bonded aromatic vinyl monomer units in the first polymer segment and the amount X2 (mass %) of the bonded aromatic vinyl monomer units in the second polymer segment (|X1-X2|) is 5 mass % or less,

[0026] The difference (Y2-Y1) between the vinyl bond amount Y1 (mol%) in the conjugated diene bonded to the first polymer segment and the vinyl bond amount Y2 (mol%) in the conjugated diene bonded to the second polymer segment is 15 mol% or more and 50 mol% or less,

[0027] The estimated glass transition temperature (estimated Tg) of the conjugated diene polymer is -72°C or higher and -40°C or lower. [2]

[0029] The conjugated diene polymer as described in the above [1], wherein the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 1.7 or more. [3]

[0031] The conjugated diene polymer as described in [1] or [2] above, wherein the ratio (R=r1 / r2) of the mass ratio (r1) of the first polymer segment to the mass ratio (r2) of the second polymer segment is 0.25 to 4. [4]

[0033] The conjugated diene polymer according to any one of [1] to [3] above, wherein the weight average molecular weight Mw is 350,000 to 1,350,000. [5]

[0035] The conjugated diene polymer according to any one of the above [1] to [4] has a nitrogen-containing modified group, and the modification rate is 60% or more. [6]

[0037] A method for producing a conjugated diene polymer, which is the method for producing a conjugated diene polymer according to any one of [1] to [5] above, comprising the following steps:

[0038] a polymerization step (P1) of forming the first polymer segment using two or more continuous reactors; and

[0039] A polymerization step (P2) in which the second polymer segment is formed at the end of the first polymer segment obtained in the above (P1),

[0040] In the above-mentioned polymerization step (P2), a polar substance is additionally added. [7]

[0042] The method for producing a conjugated diene polymer as described in the above [6], wherein a conjugated diene compound is additionally added in the polymerization step (P2). [8]

[0044] The method for producing a conjugated diene polymer as described in [6] or [7] above includes a coupling step of reacting the conjugated diene polymer with a coupling agent having a nitrogen atom-containing group after the polymerization step (P2). [9]

[0046] The method for producing a conjugated diene polymer according to [7] or [8], wherein the amount of the conjugated diene compound added in the polymerization step (P2) is 15% by mass or more of the total amount of the conjugated diene compound added.

[0047] Effects of the Invention

[0048] According to the present invention, a conjugated diene polymer can be provided that exhibits excellent wear resistance and tensile properties and can provide a rubber composition that exhibits excellent wet grip performance and winter performance. DETAILED DESCRIPTION

[0049] A specific embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail below.

[0050] The following embodiments are examples for explaining the present invention and are not intended to limit the present invention to the following contents. The present invention can be implemented by appropriately modifying the present invention within the scope of the gist of the present invention.

[0051] [Conjugated diene polymer]

[0052] The conjugated diene polymer of the present embodiment contains a conjugated diene monomer unit, and preferably contains a conjugated diene monomer unit and an aromatic vinyl monomer unit.

[0053] The conjugated diene polymer of this embodiment is a conjugated diene polymer having two or more polymer segments, wherein the absolute value (|X1-X2|) of the difference between the amount X1 (mass %) of the bonded aromatic vinyl monomer unit of the first polymer segment and the amount X2 (mass %) of the bonded aromatic vinyl monomer unit of the second polymer segment is 5 mass % or less.

[0054] Furthermore, the difference (Y2-Y1) between the vinyl bond content Y1 (mol%) in the bonded conjugated diene of the first polymer segment and the vinyl bond content Y2 (mol%) in the bonded conjugated diene of the second polymer segment is 15 mol% to 50 mol%.

[0055] Furthermore, the conjugated diene polymer has an estimated glass transition temperature (estimated Tg) calculated from the microstructure of the conjugated diene polymer of -72°C or higher and -40°C or lower.

[0056] According to the above-mentioned configuration, a conjugated diene polymer exhibits excellent wear resistance and tensile properties, and a rubber composition exhibiting excellent wet grip performance and winter performance can be obtained.

[0057] (Conjugated diene compound)

[0058] Examples of the conjugated diene compound forming the conjugated diene monomer unit include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred due to their ease of industrial availability. These may be used alone or in combination of two or more.

[0059] From the viewpoint of easy availability and easy structure control during polymer synthesis, the conjugated diene compound is preferably 1,3-butadiene or isoprene, and more preferably 1,3-butadiene.

[0060] (Aromatic vinyl compound)

[0061] Examples of aromatic vinyl compounds that form the aromatic vinyl monomer units include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred due to its ease of industrial availability. These may be used alone or in combination of two or more.

[0062] The aromatic vinyl compound is preferably styrene from the viewpoint of easy availability and ease of structure control during polymer synthesis.

[0063] (Amount of bonded aromatic vinyl monomer units X)

[0064] The amount X (mass %) of bonded aromatic vinyl monomer units in this specification is the mass fraction (mass %) of the bonded aromatic vinyl monomer units relative to the total mass of the conjugated diene polymer or the polymer segment described below.

[0065] Here, the amount of bonded aromatic vinyl monomer units can be calculated by measuring the ultraviolet absorption of the phenyl group possessed by the portion of the conjugated diene polymer from the aromatic vinyl compound (hereinafter referred to as "bonded aromatic vinyl monomer units"). In addition, when the conjugated diene polymer is composed of bonded aromatic vinyl monomer units and bonded conjugated diene monomer units, the amount of bonded conjugated diene monomer units can also be obtained from the amount of bonded aromatic vinyl monomer units obtained as described above. Specifically, it can be measured by the method described in the examples described below.

[0066] (Vinyl bond amount Y in the bonded conjugated diene)

[0067] In this specification, the vinyl bond content Y (mol%) in the bonded conjugated diene is the molar fraction (mol%) of 1,2-bonded units contained in the conjugated diene polymer or the polymer segment described below relative to the polymerized units derived from the conjugated diene.

[0068] When the conjugated diene polymer of this embodiment is a copolymer of butadiene and styrene, the amount of vinyl bonds in the conjugated diene is determined by determining the amount of vinyl bonds (1,2-bond amount) in the butadiene using the Hampton method (RR Hampton, Analytical Chemistry, 21, 923 (1949)). Specifically, the measurement can be performed using the method described in the Examples below.

[0069] (Microstructure)

[0070] The microstructure in this specification refers to the composition of a conjugated diene polymer composed of an aromatic vinyl compound and a conjugated diene compound, or a polymer segment described later, including the composition of the polymer in terms of isomers.

[0071] In the conjugated diene polymer of this embodiment, the mass of the copolymer composed of styrene and butadiene is preferably 70 mass % or more, more preferably 80 mass % or more, and even more preferably 90 mass % or more relative to the mass of the entire conjugated diene polymer.

[0072] (Content of bonded aromatic vinyl monomer unit blocks)

[0073] In the conjugated diene polymer of the present embodiment, the number of blocks formed by linking four or more bonded aromatic vinyl monomer units (hereinafter sometimes referred to as bonded aromatic vinyl monomer unit blocks) is preferably small or absent.

[0074] By reducing or eliminating the number of bonded aromatic vinyl monomer unit blocks, the conjugated diene polymer of the present embodiment tends to be less likely to have two or more glass transition temperatures (Tg).

[0075] In the case where the above-mentioned conjugated diene polymer is a butadiene-styrene copolymer, the content of the bonded aromatic vinyl monomer unit block in the conjugated diene polymer can be measured by utilizing the method (IMKOLTHOFF, et al., the method described in J.Polym.Sci.1,429 (1946)) of Kolthoff by decomposing the conjugated diene polymer and analyzing the known method for the amount of polystyrene insoluble in methanol. The content of the bonded aromatic vinyl monomer unit block measured using such a method is preferably less than 1.0 mass %, more preferably less than 0.1 mass %, further preferably 0 mass % relative to the total amount of the conjugated diene polymer. By not including the bonded aromatic vinyl monomer unit block in the conjugated diene copolymer and in the polymer segment described later, the conjugated diene polymer tends to show continuous properties to temperature variation. Thus, the sulfide formed using the conjugated diene polymer shows continuous variation in a wider temperature domain, has a tendency to be excellent in tensile strength.

[0076] (Method for estimating the glass transition temperature of a polymer): Estimated glass transition temperature (estimated Tg)

[0077] The glass transition temperature of the conjugated diene polymer of the present embodiment can be estimated using the Gordon-Taylor equation (Gordon, M., Taylor, JS, J. Appl. Chem. 1952, 2, 493) expanded to include two or more components of the following formula (1). This value is referred to as the estimated glass transition temperature.

[0078] [Number 1]

[0079]

[0080] In the above formula (1), the subscript i of the variable represents each component of the microstructure contained in the conjugated diene polymer, Δα i is the difference in thermal expansion coefficient before and after the glass transition of the homopolymer of component i, w i is the mass ratio of the conjugated diene polymer of component i, Tg i is the glass transition temperature of the homopolymer of component i, ρ i is the density of the homopolymer of component i. Both literature values and measured values may be used. For example, when the conjugated diene polymer contains styrene, when one of i is a styrene component, Δα can be used based on the thermal expansion coefficient of polystyrene (J. BRANDRUP et al, Polymer Handbook, 3rd edition, (USA), John Wiley & Sons, Inc., 1966, VI-75). i =3.6×10 -4 K -1 , Tg is used according to the measured value of glass transition temperature i =105.3℃, use ρ according to the measured value of density i =1.02g / cm 3 .

[0081] As an example, when the conjugated diene polymer is a butadiene-styrene copolymer, the amount of the bonded aromatic vinyl monomer units X all (mass %) and the vinyl bond amount Y in the bonded conjugated diene all (mol%), and the thermal expansion coefficients (Δa of polystyrene (PS), poly-1,2-butadiene (1,2-PBd), and poly-1,4-butadiene (1,4-PBd) i ), glass transition temperature (Tg i ), density (ρ i ), and the estimated glass transition temperature (estimated Tg) was calculated according to the following formula (i).

[0082] [Number 2]

[0083]

[0084] Amount of bonded aromatic vinyl monomer units X all (mass %), vinyl bond amount Y in the bonded conjugated diene all The value of the product of (mol%) has very little influence on the denominator of the above formula (i), so it can be approximated as the following formula (ii). Furthermore, the following formula (ii) can be approximated as the following formula (iii).

[0085] [Number 3]

[0086]

[0087] [Number 4]

[0088]

[0089] Specifically, when the conjugated diene polymer is a butadiene homopolymer or a butadiene-styrene copolymer, the glass transition temperature (estimated Tg) of the conjugated diene polymer can be estimated by the above formula (iii) based on numerical values generally used for design.

[0090] As described above, the amount of the bonded aromatic vinyl monomer units in the conjugated diene polymer of the present embodiment can be adjusted according to X. all (mass %), vinyl bond amount Y in the bonded conjugated diene all The mass ratio of each microstructure component can be calculated by the above formula (1) by calculating the mass ratio of each microstructure component. That is, the above formula (1) represents the mass ratio of each microstructure component relative to the amount of the bonded aromatic vinyl monomer unit X. all (mass %), vinyl bond amount Y in the bonded conjugated diene all The change in the glass transition temperature of a conjugated diene polymer is a measure of the change in the glass transition temperature of the conjugated diene polymer.

[0091] When the value of the above formula (1) is small, the glass transition temperature (Tg) of the conjugated diene polymer of the present embodiment is small. When the value of the above formula (1) is large, the glass transition temperature (Tg) becomes large.

[0092] For example, when the above formula (1) is -70, the glass transition temperature of the conjugated diene polymer is estimated to be -70°C; and when the above formula (1) is -40, the glass transition temperature is estimated to be -40°C.

[0093] Thus, the value of the above formula (1) determined from the microstructure of the polymer is generally an indicator of the glass transition temperature of the conjugated diene polymer. However, the present inventors have discovered that, when the relaxation of the conjugated diene polymer near the measured glass transition temperature is wide, the actual viscoelasticity of the sulfide does not necessarily agree with the viscoelasticity calculated from the estimated value of the glass transition temperature (estimated Tg) (this estimated Tg is based on the formula (1) calculated from the microstructure). Specifically, when the difference in the value of the formula (1) between the polymer segments described later is 33 or more, or when the mass ratio of the polymer segments described later is within the numerical range of 0.67 to 1.5, the discrepancy between the glass transition temperature (estimated Tg) estimated from the above formula (1) and the measured glass transition temperature tends to become significant. Therefore, it was discovered that, from the perspective of controlling the properties of the sulfide affected by the glass transition temperature, it is more effective to adjust the estimated glass transition temperature (estimated Tg) based on the value of formula (1) calculated from the microstructure, rather than adjusting the measured glass transition temperature of the conjugated diene polymer to a specific value. The reason for this is believed to be that DSC (differential scanning calorimetry) picks up small energy changes, so when the low Tg portion in the conjugated diene polymer begins to relax, the glass transition temperature is raised as a whole, and the measured glass transition temperature is lower than the estimated glass transition temperature. For example, even for conjugated diene polymers with the same overall microstructure, it has been confirmed experimentally that the glass transition temperature measured by DSC varies by about 2 to 5°C depending on the differences in the microstructure of each polymer segment.

[0094] In the conjugated diene polymer of this embodiment, by setting the glass transition temperature (estimated Tg) estimated from the above formula (1) to a numerical range of -72°C to -40°C, the glass transition temperature when formed into a sulfide becomes an optimal value, and the polymer tends to have an excellent balance among wet grip performance, winter performance, and wear resistance.

[0095] In the conjugated diene polymer of the present embodiment, the lower limit of the formula (1) is -72 or greater, preferably -70 or greater, and more preferably -68 or greater.

[0096] By setting the lower limit of the above formula (1) to be within the above range, the wet grip performance of the sulfide of the conjugated diene polymer of the present embodiment can be improved.

[0097] The upper limit of the value of the above formula (1) is -40 or less, preferably -44 or less, and more preferably -50 or less.

[0098] By setting the upper limit of the above formula (1) to be within the above range, the winter performance and wear resistance of the sulfide of the conjugated diene polymer of the present embodiment can be improved.

[0099] The above formula (1) can be controlled within the above numerical range by adjusting the microstructure of the conjugated diene polymer. For example, when the conjugated diene polymer of this embodiment is a butadiene-styrene polymer, the amount of bonded styrene in the conjugated diene polymer X can be adjusted by using the above formula (iii). all (mass %), vinyl bond amount Y in butadiene all (mol%) can be controlled within the above numerical range.

[0100] (polymer segment)

[0101] The conjugated diene polymer of this embodiment has two or more polymer segments.

[0102] The polymer segment is composed of a conjugated diene monomer unit and an aromatic vinyl monomer unit, or is a portion of a conjugated diene polymer composed of a conjugated diene monomer unit. The polymer segment is preferably composed of a conjugated diene monomer unit and an aromatic vinyl monomer unit.

[0103] In addition, in the polymer segment of the conjugated diene polymer of the present embodiment, it is preferred that the number of blocks formed by linking four or more bonded aromatic vinyl monomer units is small or absent.

[0104] The conjugated diene polymer of this embodiment comprises a plurality of polymer segments having different microstructures. Each polymer segment may have different amounts of bonded aromatic vinyl monomer units and vinyl bonds in the bonded conjugated diene, for example. The polymer segments can be distinguished by the methods described in the Examples below.

[0105] The conjugated diene polymer of this embodiment has two or more polymer segments. By having two or more polymer segments, a single conjugated diene polymer undergoes a glass transition across multiple temperature ranges. By setting the microstructure of the conjugated diene polymer of this embodiment within an appropriate range and controlling the difference in estimated glass transition temperature of each polymer segment calculated by substituting the amount of bonded aromatic vinyl monomer units (X1, X2) and the amount of vinyl bonds (Y1, Y2) in each polymer segment into the above formula (1) to a certain range, the sulfide tends to exhibit excellent wet grip performance and winter performance.

[0106] Among the two or more polymer segments contained in the conjugated diene polymer of this embodiment, the polymer segment whose estimated glass transition temperature calculated by the above formula (1) is 5°C or more lower than the average estimated glass transition temperature of the conjugated diene polymer of this embodiment is referred to as the "first polymer segment", and the polymer segment whose estimated glass transition temperature is 5°C or more higher than the average estimated glass transition temperature of the conjugated diene polymer of this embodiment is referred to as the "second polymer segment".

[0107] The first and second polymer segments may each comprise a plurality of polymer segments, but are preferably each composed of a single polymer segment for ease of production. Furthermore, to balance wet grip performance and winter performance of the sulfide using the conjugated diene polymer of this embodiment, the ratio of the mass of the first and second polymer segments to the total mass of the conjugated diene polymer is preferably 70% or greater, more preferably 80% or greater, and even more preferably 90% or greater.

[0108] Conventional conjugated diene polymers produced through continuous polymerization consist of a single polymer segment with a uniform microstructure and exhibit a sharp glass transition behavior within a narrow temperature range. Typically, when winter performance is important, conjugated diene polymers with low glass transition temperatures are used to maximize flexibility around -30°C to -10°C. However, since they do not undergo a glass transition near 0°C and are less prone to energy absorption, they tend to exhibit poor wet grip performance.

[0109] On the other hand, in the conjugated diene polymer of this embodiment, the multiple polymer chain segments have different glass transition temperatures, which slows the glass transition behavior. Therefore, it fully softens at -30 to -10°C, can exhibit good winter performance, and can increase energy absorption near 0°C, and also tends to be excellent in wet grip.

[0110] In the two polymer segments constituting the conjugated diene polymer of this embodiment, the larger the difference in glass transition temperature between the two polymer segments, the slower the glass transition behavior becomes, and the more pronounced the above tendency becomes, thereby tending to achieve a balance between winter performance and wet grip performance.

[0111] In the conjugated diene polymer of this embodiment, in order to increase the glass transition temperature difference between polymer segments, it is preferred to increase the difference in the amount of aromatic vinyl monomer units in the first polymer segment and the difference in the amount of vinyl bonds in the bonded conjugated diene.

[0112] On the other hand, if the difference in the amount of aromatic vinyl monomer units between the two polymer segments increases, the compatibility of the two polymer segments deteriorates, and the tensile strength of the resulting sulfide tends to deteriorate. From this perspective, in order to obtain a sulfide having excellent tensile strength, it is effective to adjust the difference in the amount of aromatic vinyl monomer units between the two polymer segments to an appropriate range and to increase the difference in the amount of vinyl bonds in the bonded conjugated diene.

[0113] The lower limits of the amount of aromatic vinyl monomer units X1 (mass %) in the first polymer segment and the amount of aromatic vinyl monomer units X2 (mass %) in the second polymer segment are preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 9% by mass or more in each polymer segment. Furthermore, the upper limits thereof are preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 23% by mass or less in each polymer segment.

[0114] The lower limit of the vinyl bond amount Y1 (mol%) in the bonded conjugated diene of the first polymer segment is preferably 14 mol% or more, more preferably 16 mol% or more, and even more preferably 17 mol% or more. The upper limit is preferably 40 mol% or less, more preferably 35 mol% or less, even more preferably 30 mol% or less, and even more preferably 23 mol% or less.

[0115] On the other hand, the lower limit of the vinyl bond content Y2 (mol%) in the conjugated diene bonded to the second polymer segment is preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 50 mol% or more, and even more preferably 55 mol% or more. The upper limit is preferably 65 mol% or less, more preferably 62 mol% or less, and even more preferably 61 mol% or less.

[0116] The vinyl bond amounts Y1 and Y2 in the conjugated diene bonded to the polymer segment may be within a range formed by arbitrarily combining the above upper and lower limits.

[0117] The difference (Y2-Y1) between the amount of vinyl bonds Y1 (mol%) in the bonded conjugated diene of the first polymer segment of the conjugated diene polymer of this embodiment and the amount of vinyl bonds Y2 (mol%) in the bonded conjugated diene of the second polymer segment is 15 mol% to 50 mol%, preferably 20 mol% to 45 mol%, and more preferably 25 mol% to 45 mol%.

[0118] When (Y2-Y1) is 15 mol% or more, the resulting sulfide tends to have an excellent balance between wet grip performance and winter performance. On the other hand, when (Y2-Y1) is 50 mol% or less, phase separation of the conjugated diene polymer is suppressed, and the resulting sulfide tends to have excellent tensile strength.

[0119] The value of (Y2-Y1) can be measured by the method described in the Examples below, and can be controlled within the above numerical range by adjusting the amount of the polar substance added in the polymerization steps (P1 and P2) described below.

[0120] The absolute value (|X1-X2|) of the difference between the amount X1 (mass %) of the bonded aromatic vinyl monomer in the first polymer segment of the conjugated diene polymer of this embodiment and the amount X2 (mass %) of the bonded aromatic vinyl monomer in the second polymer segment is 5 mass % or less, preferably 3 mass % or less, and more preferably 2 mass % or less.

[0121] When (|X1-X2|) is 5% by mass or less, the distribution of the aromatic vinyl monomer units becomes uniform, microphase separation of the conjugated diene polymer is suppressed, and the sulfide thereof tends to have further excellent tensile properties.

[0122] The absolute value of the difference in the amount of bonded aromatic vinyl monomer in the polymer segments can be measured by the method described in the Examples below and can be controlled within the above numerical range by adjusting the amount of aromatic vinyl monomer added in the polymerization step of each polymer segment.

[0123] In the conjugated diene polymer of this embodiment, the basic design concept is: in order to make the second polymer segment have an estimated glass transition temperature that is 5°C or more higher than the average estimated glass transition temperature of the conjugated diene polymer, the vinyl bond content Y2 (mol%) of the second polymer segment is set to be higher than the vinyl bond content Y1 (mol%) of the first polymer segment, and with respect to the amount of bonded aromatic vinyl monomer, there is no difference between the two polymer segments.

[0124] In the present embodiment, the difference in the absolute value of the bonded aromatic vinyl monomer amount of the two segments is set to 5% by mass or less in order to allow for errors during manufacturing. The content of the aromatic vinyl monomer unit is also a major factor affecting the estimated glass transition temperature. Therefore, although a design in which the bonded aromatic vinyl monomer unit amount of each polymer segment is different can be performed, by reducing the difference in the bonded aromatic vinyl monomer unit amount of the two polymer segments, as described above, it is possible to expect that the distribution of the aromatic vinyl monomer unit is uniform and the advantage of suppressing microphase separation can be suppressed.

[0125] The estimated glass transition temperature of the polymer segment can be calculated using formula (1) in the same manner as for the conjugated diene polymer.

[0126] To the conjugated diene polymer of the present embodiment, a conjugated diene monomer unit may be added before the coupling step in order to improve the reactivity between the conjugated diene polymer and the coupling agent.

[0127] In the conjugated diene polymer of this embodiment, polymer segments may be directly bonded to each other or may be bonded to each other through a coupling agent.

[0128] (Ratio R of the mass ratio of the first polymer segment to the mass ratio of the second polymer segment)

[0129] In the conjugated diene polymer of the present embodiment, the first and second polymer segments preferably have a predetermined mass ratio.

[0130] The mass ratio of the polymer segments refers to the mass ratio (r) of each polymer segment relative to the entire conjugated diene polymer.

[0131] The mass ratio of the first and second polymer segments of the conjugated diene polymer of this embodiment is defined as the mass ratio of the polymer segments obtained in steps P1 and P2, which are polymerization steps of the respective polymer segments, relative to the total mass of the conjugated diene polymer.

[0132] The ratio of the mass ratio of the first polymer segment (r1) to the mass ratio of the second polymer segment (r2) (R = r1 / r2) is preferably 0.25 to 4, more preferably 0.33 to 3, and even more preferably 0.4 to 2.4. When the lower limit of R is 0.25 or greater, excellent fuel efficiency during vulcanization tends to be achieved. Furthermore, when the upper limit of R is 4 or less, excellent processability when formed into a vulcanizate tends to be achieved.

[0133] The above-mentioned R can be measured by the method described in the examples described later. In the production process of the conjugated diene polymer of this embodiment, the conditions such as the polymerization time, polymerization temperature, monomer addition amount, and vinyl bond amount in the polymerization process of each polymer segment can be adjusted to control it within the above-mentioned numerical range.

[0134] The method for introducing multiple polymer segments into a conjugated diene polymer molecule is carried out, as described below, by using a continuous solution polymerization method in which multiple reactors are arranged in series. A conjugated diene compound, an aromatic vinyl compound, a polar substance, and a solvent are sequentially added to each reactor. The substances added sequentially may be the same or different between the reactors.

[0135] (Glass transition temperature)

[0136] The glass transition temperature (Tg) of the conjugated diene polymer of this embodiment is preferably -72°C or higher, more preferably -67°C or higher. Furthermore, the glass transition temperature of the conjugated diene polymer of this embodiment is -40°C or lower, more preferably -45°C or lower. When the glass transition temperature falls within the above range, the sulfide of the conjugated diene polymer of this embodiment tends to exhibit even better fuel efficiency.

[0137] The conjugated diene polymer of the present embodiment, in which the estimated Tg of the above formula (1) satisfies the numerical range of -72°C to -40°C, has a measured glass transition temperature (Tg) basically within the above range.

[0138] The glass transition temperature (Tg) may be within a range formed by arbitrarily combining the above upper and lower limits. The glass transition temperature of a conjugated diene polymer can be measured in accordance with ISO 22768:2006. More specifically, the glass transition temperature is determined by performing differential scanning calorimetry (DSC) while heating the polymer within a specified temperature range to record a DSC curve, with the inflection point of the DSC curve being the glass transition temperature. Specifically, the glass transition temperature can be determined by the method described in the Examples below.

[0139] The conjugated diene polymer of the present embodiment may contain plasticizer components such as resin and process oil described below. However, these components must be removed in DSC measurement for determining the glass transition temperature of the conjugated diene copolymer of the present embodiment.

[0140] The glass transition temperature of a conjugated diene polymer varies depending on the amount of bound aromatic vinyl monomer units and the amount of vinyl bonds in the bound conjugated diene. Specifically, the glass transition temperature increases as the amount of bound aromatic vinyl monomer units and the amount of vinyl bonds in the bound conjugated diene increase, while the glass transition temperature decreases as the amount of bound aromatic vinyl monomer units and the amount of vinyl bonds in the bound conjugated diene decrease.

[0141] In the conjugated diene polymer of the present embodiment, by setting the estimated Tg calculated from the above formula (1) to -72°C or higher and -40°C or lower, the actually measured glass transition temperature can be set to a preferred range.

[0142] (weight average molecular weight)

[0143] The weight average molecular weight (Mw) of the conjugated diene polymer of the present embodiment measured by GPC measurement is preferably 35×10 4 More than 40×10 4 More preferably, 45×10 4 When the lower limit of the weight average molecular weight measured by GPC measurement method satisfies the above range, the wear resistance of the sulfide tends to be excellent. In addition, the above weight average molecular weight is preferably 135×10 4 less than 95×10 4 Below, more preferably 75×10 4 When the upper limit of the weight average molecular weight satisfies the above range, the filler tends to have better dispersibility in the sulfide thereof and better processability.

[0144] The weight average molecular weight may be within a range formed by arbitrarily combining the above upper limit value and lower limit value.

[0145] The weight average molecular weight of the conjugated diene polymer can be measured by GPC measurement, specifically, by the method described in the examples below.

[0146] (number average molecular weight)

[0147] The number average molecular weight of the conjugated diene polymer of this embodiment measured by GPC is preferably 10×10 4 More than 15×10 4 More preferably, 20×10 4 When the lower limit of the number average molecular weight measured by GPC measurement method satisfies the above range, the wear resistance of the sulfide tends to be excellent. In addition, the above number average molecular weight is preferably 100×10 4 less than 70×10 4 Below, more preferably 50×10 4 When the upper limit of the number average molecular weight satisfies the above range, the dispersibility of the filler in its sulfide is more excellent and the processability is excellent. The number average molecular weight can be within the range formed by arbitrarily combining the upper limit and the lower limit. The number average molecular weight of the conjugated diene polymer can be measured by GPC determination method, and can be measured by the method described in the examples described below.

[0148] The weight average molecular weight and number average molecular weight of the conjugated diene polymer can be controlled within the above numerical ranges by adjusting the ratio of the amount of the polymerization initiator to the amount of the monomer, and the type and amount of the coupling agent.

[0149] (Molecular weight distribution)

[0150] The molecular weight distribution of the conjugated diene polymer of the present embodiment is represented by the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn). In the conjugated diene polymer of the present embodiment, the molecular weight distribution is preferably 1.7 or more. Conjugated diene polymers having a molecular weight distribution within this range tend to have a more excellent processability when made into sulfides.

[0151] The molecular weight distribution of the conjugated diene polymer of the present embodiment is more preferably 1.75 or more, and even more preferably 1.8 or more, and is more preferably 2.4 or less, and even more preferably 2.2 or less.

[0152] (Modification rate)

[0153] The conjugated diene polymer of the present embodiment preferably has a nitrogen-containing modifying group.

[0154] As used herein, the term "modification ratio" refers to the percentage by mass of the modified conjugated diene polymer component having a specific functional group (having affinity or bonding reactivity with a filler) in the polymer molecule relative to the total amount of the conjugated diene polymer mixture, when a conjugated diene polymer is modified with a modifier having a nitrogen atom, and an unmodified conjugated diene polymer. Therefore, when the specific functional group contains a nitrogen atom, the modification ratio represents the mass ratio (%) of the modified conjugated diene polymer containing a nitrogen atom relative to the total amount of the conjugated diene polymer mixture.

[0155] In this specification, the "modified conjugated diene polymer" refers to a modified conjugated diene polymer and a mixture of a modified conjugated diene polymer and an unmodified conjugated diene polymer.

[0156] For example, in the case of a conjugated diene polymer including a modified conjugated diene polymer obtained by reacting a nitrogen atom-containing modifier with the terminal end of a conjugated diene polymer, the mass ratio of the modified conjugated diene polymer having a nitrogen atom-containing functional group derived from the nitrogen atom-containing modifier relative to the total amount of the modified conjugated diene polymer is the modification rate.

[0157] The modification rate can be measured by a chromatography method that can separate modified components containing a functional group from unmodified components.

[0158] Examples of methods using this chromatography include a method using a gel permeation chromatography column filled with a polar substance such as silica that adsorbs specific functional groups, and performing quantitative determination by comparison with an internal standard of a non-adsorbed component.

[0159] More specifically, the modification rate can be obtained by measuring the amount of adsorption on the silica column based on the difference between the chromatogram obtained by measuring a sample solution containing the sample and a low-molecular-weight internal standard polystyrene using a polystyrene gel column and the chromatogram obtained by measuring the sample solution using a silica column. More specifically, the modification rate can be measured using the method described in the Examples.

[0160] In the conjugated diene polymer of the present embodiment, the modification rate can be controlled by adjusting the amount of the modifier added and the reaction method.

[0161] For example, the following methods can be combined and the polymerization conditions can be controlled to achieve the above-mentioned modification rate: a method of using an organic lithium compound having at least one nitrogen atom in the molecule as a polymerization initiator; a method of copolymerizing a monomer having at least one nitrogen atom in the molecule; a method of using a modifier of the structural formula described later.

[0162] In the conjugated diene polymer of the present embodiment, the modification rate is preferably 60% or more, more preferably 65% or more, and even more preferably 70% or more, from the viewpoint of the fuel efficiency of the sulfide.

[0163] [Method for producing conjugated diene polymer]

[0164] The method for producing a modified conjugated diene polymer according to the present embodiment includes the following steps:

[0165] A polymerization step (P1) of forming a first polymer segment using two or more continuous reactors; and

[0166] a polymerization step (P2) in which the end of the first polymer segment obtained in the polymerization step (P1) is converted into the second polymer segment;

[0167] There is a step of additionally adding a polar substance in the above-mentioned polymerization step (P2).

[0168] (Polymerization initiator)

[0169] In the polymerization step (P1), it is preferred to use a polymerization initiator.

[0170] In addition, in the polymerization step (P2), it is preferable not to use a polymerization initiator.

[0171] As the polymerization initiator, at least an organic monolithium compound can be used.

[0172] Examples of the organic monolithium compound include, but are not limited to, low molecular weight compounds and solubilized oligomer organic monolithium compounds.

[0173] Examples of the organic monolithium compound include compounds having a carbon-lithium bond, compounds having a nitrogen-lithium bond, and compounds having a tin-lithium bond in terms of the bonding form between the organic group and the lithium.

[0174] The amount of the organic monolithium compound used as a polymerization initiator is preferably determined according to the molecular weight of the desired conjugated diene polymer or modified conjugated diene polymer.

[0175] The amount of monomers such as conjugated diene compounds used relative to the amount of polymerization initiator used is correlated with the degree of polymerization, that is, it tends to be correlated with the number average molecular weight and weight average molecular weight.

[0176] Therefore, in order to increase the molecular weight of the conjugated diene polymer, the amount of the polymerization initiator used can be adjusted to be reduced, and in order to decrease the molecular weight, the amount of the polymerization initiator used can be adjusted to be increased.

[0177] When nitrogen atoms are introduced into a conjugated diene polymer using a polymerization initiator, the organic monolithium compound is preferably an alkyllithium compound having a substituted amino group or lithium dialkylamide, from the perspective of being used in one method of introducing nitrogen atoms into a conjugated diene polymer.

[0178] In this case, a conjugated diene polymer having a nitrogen atom constituting an amino group at the polymerization initiation terminal can be obtained.

[0179] The substituted amino group refers to an amino group having no active hydrogen or a structure in which the active hydrogen is protected.

[0180] Examples of the alkyllithium compound having an amino group without active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium.

[0181] Examples of the alkyllithium compound having an amino group with active hydrogen protected include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0182] Examples of the lithium dialkylamide include, but are not limited to, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidine, lithium piperidine, lithium heptamethyleneimide, lithium morpholine, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.

[0183] These organic monolithium compounds having a substituted amino group can also be used as organic monolithium compounds that are soluble oligomers by reacting with a small amount of a polymerizable monomer such as 1,3-butadiene, isoprene, or styrene.

[0184] The polymerization initiator may be a substance produced by reacting an aromatic vinyl compound and / or a conjugated diene compound having a substituted amino group with an organic monolithium compound, or may be a substance capable of introducing a functional group into one terminal of a polymer chain.

[0185] As the organic monolithium compound, an alkyllithium compound is preferably used from the viewpoint of ease of industrial availability and ease of polymerization reaction control. In this case, a conjugated diene polymer having an alkyl group at the polymerization initiation terminal can be obtained.

[0186] Examples of the alkyllithium compound include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium.

[0187] As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoint of ease of industrial availability and ease of polymerization reaction control.

[0188] These organic monolithium compounds may be used alone or in combination of two or more, or may be used in combination with other organic metal compounds.

[0189] Examples of the other organometallic compounds include alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds.

[0190] Examples of alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds, as well as alkoxides, sulfonates, carbonates, and amide compounds of alkaline earth metals.

[0191] Examples of the organomagnesium compound include dibutylmagnesium and ethylbutylmagnesium, and examples of other organometallic compounds include organoaluminum compounds.

[0192] In the method for producing the conjugated diene polymer of the present embodiment, a coupling step described later may be implemented after the above-mentioned polymerization step. The weight average molecular weight of the conjugated diene polymer before the above-mentioned coupling step is controlled by the amount of polymerization initiator relative to the conjugated diene compound and the aromatic vinyl compound. The lower the amount of polymerization initiator, the lower the weight average molecular weight of the conjugated diene polymer. When the total mass of the conjugated diene compound and the aromatic vinyl compound is set to 100 kg, the amount of polymerization initiator is preferably 0.15 mol or more and 1.5 mol or less.

[0193] (Polar substances)

[0194] In the method for producing a conjugated diene polymer according to the present embodiment, a polar substance is added in the polymerization step (P2) of forming the second polymer segment.

[0195] Polar substances tend to enable random copolymerization of aromatic vinyl compounds and conjugated diene compounds, and can also be used as vinylating agents for controlling the microstructure of the conjugated diene moiety. They also tend to be effective in promoting polymerization reactions.

[0196] Polar substances include, but are not limited to, ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, 2,2-bis(2-tetrahydrofuryl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidylethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alcoholate compounds such as potassium tert-amylate, potassium tert-butoxide, sodium tert-butoxide, and sodium amylate; and phosphine compounds such as triphenylphosphine.

[0197] These polar substances may be used alone or in combination of two or more.

[0198] The amount of the polar substance used is not particularly limited and can be selected depending on the purpose, but is preferably from 0.01 mol to 100 mol per 1 mol of the polymerization initiator used in the polymerization step.

[0199] Such polar substances (vinylating agents) can be used in appropriate amounts as modifiers of the microstructure of the conjugated diene portion of conjugated diene polymers, depending on the desired vinyl bond content. Most polar substances also exhibit an effective randomizing effect in the copolymerization of conjugated diene compounds and aromatic vinyl compounds, tending to adjust the randomness of the aromatic vinyl monomer units and conjugated diene monomer units in each polymer segment.

[0200] As a method for randomizing the conjugated diene monomer units and the aromatic vinyl monomer units, for example, the following method can be used, as described in Japanese Patent Application Laid-Open No. 59-140211: a copolymerization reaction is initiated with the total amount of styrene and a portion of 1,3-butadiene, and the remaining 1,3-butadiene is intermittently added during the copolymerization reaction. The 1,3-butadiene added here is added to adjust the randomness and does not necessarily form polymer segments.

[0201] (Polymerization process)

[0202] In the method for producing a conjugated diene polymer of this embodiment, polymerization steps are performed using a continuous reactor comprising two or more reactors connected in series, and a polymerization step (P1) for obtaining a first polymer segment and a polymerization step (P2) for obtaining a second polymer segment are carried out.

[0203] The polymerization steps (P1) and (P2) can each use one reactor or two or more reactors connected together. The reactor shape may be a tank-type reactor equipped with a stirrer, a tubular reactor, or the like.

[0204] The polymerization steps (P1) and (P2) do not necessarily need to be allocated to each reactor, and for example, the polymerization step (P2) may be started downstream of the first reactor. Each reactor may have a temperature control function.

[0205] (Solid content)

[0206] In the method for producing a conjugated diene polymer according to the present embodiment, the target conjugated diene polymer can be recovered in a predetermined solid amount.

[0207] In addition, the solid content in this specification refers to the mass of the conjugated diene polymer recovered per unit time at a measurement point.

[0208] The mass of the conjugated diene polymer includes only the mass of the polymer converted to a polymer by reaction with the polymerization initiator, and does not include the mass of the unreacted conjugated diene compound, aromatic vinyl compound, solvent, etc.

[0209] (Conversion Rate)

[0210] In the method for producing a conjugated diene polymer according to the present embodiment, the “conversion rate” is defined as the mass of the conjugated diene compound and the aromatic vinyl compound that has completed the reaction and converted into the conjugated diene polymer at the time of measurement, out of the total mass.

[0211] That is, it is determined from the following formula (2) using the above-mentioned solid content.

[0212] [Number 5]

[0213]

[0214] Furthermore, the conversion rates of the conjugated diene compound and the aromatic vinyl compound were determined using the following formulas (3) and (4), respectively, using the amounts of bonded conjugated diene monomer units and bonded aromatic vinyl monomer units in the solid content obtained in the above solid content measurement.

[0215] [Number 6]

[0216]

[0217] It should be noted that the denominator in the calculation of the above conversion rate is the total mass of the monomers added during the entire polymerization process (P1 and P2). Therefore, in the case of the conversion rate at the end of P1, even if all the monomers added up to that point have reacted, the conversion rate will not reach 100%.

[0218] From the perspective of controlling the physical properties of the conjugated diene polymer of this embodiment, the conversion rate is preferably 95% or higher by the time the polymerization step is completed. Specifically, the conversion rate only needs to be 95% or higher at the time the polymerization step (P2) is completed, and the conversion rate in the polymerization step (P1) does not need to fall within this range.

[0219] By setting the conversion rate within the above range, the amount of bound aromatic vinyl monomer units in the conjugated diene polymer can be controlled by adjusting the ratio of the total amount of the conjugated diene compound to the total amount of the aromatic vinyl compound added in the polymerization step. all , structural control becomes easy.

[0220] In the method for producing a conjugated diene system according to the present embodiment, it is preferred that the first polymer segment is obtained in the polymerization step (P1), and the polymerization step (P1) includes a raw material supply section for continuously supplying a conjugated diene compound, an aromatic vinyl compound, an inert solvent, a polymerization initiator, and a polar substance from one end of the reactor, and a discharge section for continuously discharging the polymer solution at the end opposite to the raw material supply section.

[0221] The conjugated diene polymer solution after the polymerization step (P1) is continuously distilled from the reactor and fed to the next step. In a preferred embodiment, the next step is the polymerization step (P2) of the second polymer segment described below.

[0222] The polymerization step (P2) for obtaining the second polymer segment uses one or more connected reactors, similar to the polymerization step (P1). In this case, by adding a conjugated diene compound, an aromatic vinyl compound, an inert solvent, a polar substance, or the like to the middle portion of the reactor or to the piping connecting the preceding step to the present step, a second polymer segment having a greater amount of vinyl bonds in the conjugated diene than that synthesized in the preceding polymerization step is introduced at the end of the first polymer segment. This allows the formation of a second polymer segment having a higher Tg than that of the first polymer segment.

[0223] Since the second polymer segment has a higher vinyl bond content Y2 (mol%) than the first polymer segment, the conditions in the polymerization step (P2) for forming the second polymer segment are set so that the vinyl bond content of the polymer increases.

[0224] In the polymerization step (P2), one or more polar substances are additionally added. The addition of the polar substance increases the amount of vinyl bonds in the conjugated diene bonded to the second polymer segment compared to the first polymer segment, thereby increasing the difference in the amount of vinyl bonds in the diene bonded to the first polymer segment and the second polymer segment.

[0225] Regarding the amount of polar substance added in the polymerization step, the total amount of polar substance added in the polymerization step (P1) and the polymerization step (P2) is preferably 0.01 mol or more and 100 mol or less relative to 1 mol of the polymerization initiator. In order to control the difference in the amount of vinyl bonds in the bonded conjugated dienes of the first polymer segment and the second polymer segment within the above range, the respective addition amounts can be selected. The distribution of the added polar substance in the polymerization steps (P1) and (P2) varies depending on various factors such as the type of polar substance, polymerization temperature, and the shape of the reactor, and is therefore not particularly limited. For example, the concentration of the polar substance in the polymerization step (P2) is preferably 3 times or more and 20 times or less that of the polymerization step (P1).

[0226] After the polymerization step (P2), the conjugated diene polymer solution is continuously distilled from the reactor and fed to the next step. As an example, the feeding destination may be the coupling step described below.

[0227] In the conjugated diene polymer of the present embodiment, in order to make the absolute value of the difference (X1-X2) between the amount of bonded aromatic vinyl monomer units of the first polymer segment and the second polymer segment be 5% by mass or less, the conjugated diene compound and the aromatic vinyl compound added in the polymerization process need to react in similar proportions in the polymerization process (P1) and the polymerization process (P2), respectively. To achieve this, it is preferred to reduce the difference in conversion rate between the conjugated diene compound and the aromatic vinyl compound in the polymerization process (P1). For example, when the conversion rate of the aromatic vinyl compound is lower than the conversion rate of the conjugated diene compound, the amount of bonded aromatic vinyl monomer units of the first polymer segment is reduced; instead, a large amount of aromatic vinyl compound flows into the polymerization process (P2), and the difference in the amount of bonded aromatic vinyl monomer units of the first polymer segment and the second polymer segment is enlarged. On the other hand, when the absolute value of the difference in conversion rate between the two in the polymerization step (P1) is small, the first polymer segment and the second polymer segment both contain aromatic vinyl monomer units in the same proportion, and thus the difference in the amount of bonded aromatic vinyl monomer units is small. The difference in conversion rate between the conjugated diene compound and the aromatic vinyl compound is preferably less than 10% by mass, more preferably less than 8% by mass, and even more preferably less than 6% by mass.

[0228] If add polar substance, then can expect the effect that improves the speed of response of aromatic vinyl compound, therefore by increasing the addition of polar substance, also can reduce the difference of the conversion rate of conjugated diene compound and aromatic vinyl compound.On the other hand, polar substance also plays a role as vinylating agent usually, by increasing addition, the vinyl bond amount of generated segment tends to improve.Therefore, although polar substance amount is one of variable for conversion rate control, it is difficult to select in the design of control vinyl bond amount.Compared with the conversion rate control based on the addition of polar substance, adjusting the supply amount of the monomer of each segment on the basis of having set the addition of polar substance, polymerization temperature is preferred mode.

[0229] In order to reduce the difference in conversion rate between the conjugated diene compound and the aromatic vinyl compound, it is effective to add the conjugated diene compound and the aromatic vinyl compound to be added in the polymerization step separately in the polymerization step (P1) and the polymerization step (P2). By reducing the amount of any monomer with a large reaction rate constant added in the polymerization step (P1), it is possible to induce a decrease in reaction rate due to raw material depletion, thereby making the conversion rate uniform at the end of the polymerization step (P1).

[0230] In order to control the conversion rate, if there is a compound whose amount added in the polymerization step (P1) is insufficient relative to the total amount that should be added due to the addition of monomers separately, the insufficient amount is added in the polymerization step (P2). As mentioned above, the conversion rate at the end of the polymerization step is preferably 95% or more, so the amount of bonded aromatic vinyl monomer units in the conjugated diene polymer is X all Of course, it is approximately equal to the ratio of (aromatic vinyl compound) to (conjugated diene compound + aromatic vinyl compound). This value is approximately equal to the amount X1 of bonded aromatic vinyl monomer units in the first polymer segment synthesized in the polymerization step (P1).

[0231] For example, in a conventional copolymerization reaction using n-hexane as a solvent and 1,3-butadiene and styrene as the conjugated diene compound and aromatic vinyl compound, respectively, which are polymerizable monomers, the polymerization reaction rate of the conjugated diene compound is higher than that of the aromatic vinyl compound. Therefore, the conversion rate of the conjugated diene compound tends to be higher than that of the aromatic vinyl compound.

[0232] Here, in order to reduce the difference in conversion rates between the two compounds, assuming that the conversion rates of the conjugated diene compound and the aromatic vinyl compound are A and B, respectively, when the polymerization is completed in the P1 step alone, the difference in conversion rates between the conjugated diene compound and the aromatic vinyl compound can be reduced by adding the conjugated diene compound in the P1 step according to the ratio of B divided by A and adding the remaining amount in the P2 step.

[0233] The amount of the conjugated diene compound added in the polymerization step (P2) is preferably 15% by mass or more of the total amount of the conjugated diene compound added, more preferably 20% by mass or more, and even more preferably 25% by mass or more. By setting the amount added in the polymerization step (P2) to 15% by mass or more of the total amount of the conjugated diene compound added, it is likely that the absolute value of the difference (X1-X2) between the amount X1 (mass %) of the bonded aromatic vinyl monomer units in the first polymer segment and the amount X2 (mass %) of the bonded aromatic vinyl monomer units in the second polymer segment is 5% by mass or less, and the ratio of the mass ratio (r1) of the first polymer segment to the mass ratio (r2) of the second polymer segment (R=r1 / r2) is within a numerical range of 0.25 to 4.00.

[0234] In the conjugated diene polymer of this embodiment, the ratio of the mass ratio (r1) of the first polymer segment to the mass ratio (r2) of the second polymer segment (R = r1 / r2) can be controlled by utilizing the ratio of the conjugated diene compound and the aromatic vinyl compound added in the above-mentioned polymerization step (P2).

[0235] By reducing the ratio of the conjugated diene compound to the aromatic vinyl compound added in the polymerization step (P2), the conversion rate of each component in the polymerization step (P1) is increased, and R is increased. In this case, it is preferable to control so that the difference between the conversion rate of the conjugated diene compound and the conversion rate of the aromatic vinyl compound is reduced.

[0236] From the viewpoint of reaction controllability, a high conversion rate is preferably achieved in each polymerization step. However, R can also be controlled by supplying unreacted conjugated diene compound and / or aromatic vinyl compound in the previous polymerization step to the next step.

[0237] The production of the conjugated diene polymer of this embodiment may include predetermined steps before and after the polymerization step (P1) and before and after the polymerization step (P2). For example, a step of synthesizing a polymer different from the first polymer segment and the second polymer segment may be included.

[0238] The polymerization temperature in the polymerization step of the conjugated diene polymer of this embodiment is preferably a temperature at which living anionic polymerization is carried out. From the perspective of productivity, it is more preferably 0°C or higher and even more preferably 120°C or lower. This range tends to ensure a sufficient amount of the modifier reacted with the active terminals after completion of polymerization. Even more preferably, it is 50°C or higher and 100°C or lower.

[0239] In the production of the conjugated diene polymer of this embodiment, a high molecular weight distribution can be achieved by simply reducing the height (L) / diameter (D) ratio of the tank reactor. Reducing L / D increases the residence time distribution within the reactor, thereby increasing the variation in reaction time per polymerization initiator molecule and improving the molecular weight distribution.

[0240] (Coupling process)

[0241] In the method for producing a conjugated diene polymer of this embodiment, a step of coupling the active ends of the conjugated diene polymer obtained through the polymer segment polymerization step using a coupling agent (e.g., a reactive compound having three or more functional groups) and / or a step of modifying the active ends of the conjugated diene polymer using a modifier having a nitrogen atom-containing group (preferably a coupling agent having a nitrogen atom-containing group) can be implemented.

[0242] Hereinafter, the step of coupling and / or the step of modifying is referred to as a coupling step.

[0243] In the coupling step, one of the active terminals of the conjugated diene polymer is subjected to a modification reaction using a coupling agent or a modifier having a nitrogen atom to obtain a modified conjugated diene polymer.

[0244] <Coupling agent>

[0245] In the method for producing a conjugated diene polymer according to the present embodiment, the coupling agent used in the coupling step may have any structure as long as it is a trifunctional or higher-functional reactive compound, but is preferably a trifunctional or higher-functional reactive compound having a silicon atom.

[0246] Examples of the trifunctional or higher-functional reactive compound having a silicon atom include, but are not limited to, halogenated silane compounds, epoxidized silane compounds, vinylated silane compounds, alkoxysilane compounds, and alkoxysilane compounds containing a nitrogen-containing group.

[0247] Examples of the halogenated silane compound serving as a coupling agent include, but are not limited to, methyltrichlorosilane, tetrachlorosilane, tris(trimethylsiloxy)chlorosilane, tris(dimethylamino)chlorosilane, hexachlorodisilane, bis(trichlorosilyl)methane, 1,2-bis(trichlorosilyl)ethane, 1,2-bis(methyldichlorosilyl)ethane, 1,4-bis(trichlorosilyl)butane, and 1,4-bis(methyldichlorosilyl)butane.

[0248] Examples of the epoxidized silane compound serving as the coupling agent include, but are not limited to, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and epoxy-modified silicone.

[0249] <Modifier Having a Nitrogen Atom-Containing Group>

[0250] Examples of the modifier having a nitrogen atom-containing group include, but are not limited to, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, carbonyl compounds containing a nitrogen atom group, vinyl compounds containing a nitrogen atom group, and epoxy compounds containing a nitrogen atom group.

[0251] As the modifier having a nitrogen atom-containing group, an amine compound having no active hydrogen is preferred, and examples thereof include tertiary amine compounds, protected amine compounds in which the active hydrogen is substituted with a protecting group, imine compounds represented by the general formula -N=C, and alkoxysilane compounds bonded to the nitrogen atom-containing group.

[0252] Examples of the isocyanate compound as a modifier having a nitrogen atom-containing group include, but are not limited to, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate (C-MDI), phenyl isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, butyl isocyanate, and 1,3,5-benzene triisocyanate.

[0253] Examples of isocyanuric acid derivatives as modifiers having a nitrogen atom-containing group include, but are not limited to, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 1,3,5-tris(3-triethoxysilylpropyl)isocyanurate, 1,3,5-tris(oxiran-2-yl)-1,3,5-triazinane-2,4,6-trione, 1,3,5-tris(isocyanatomethyl)-1,3,5-triazinane-2,4,6-trione, and 1,3,5-trivinyl-1,3,5-triazinane-2,4,6-trione.

[0254] Examples of carbonyl compounds as modifiers having a nitrogen atom-containing group include, but are not limited to, 1,3-dimethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-(2-methoxyethyl)-2-imidazolidinone, N-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-methyl-2-quinolone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)diphenyl Ketone, methyl-2-pyridyl ketone, methyl-4-pyridyl ketone, propyl-2-pyridyl ketone, di-4-pyridyl ketone, 2-benzoylpyridine, N,N,N',N'-tetramethylurea, N,N-dimethyl-N',N'-diphenylurea, N,N-diethylcarbamic acid methyl ester, N,N-diethylacetamide, N,N-dimethyl-N',N'-dimethylaminoacetamide, N,N-dimethylpicolinamide, N,N-dimethylisonicotinamide, etc.

[0255] Examples of vinyl compounds as modifiers having a nitrogen atom-containing group include, but are not limited to, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-methylmaleimide, N-methylphthalimide, N,N-bistrimethylsilylacrylamide, morpholinoacrylamide, 3-(2-dimethylaminoethyl)styrene, (dimethylamino)dimethyl-4-vinylphenylsilane, 4,4'-ethylidenebis(N,N-dimethylaniline), 4,4'-ethylidenebis(N,N-diethylaniline), 1,1-bis(4-morpholinophenyl)ethylene, and 1-phenyl-1-(4-N,N-dimethylaminophenyl)ethylene.

[0256] Epoxy compounds as modifiers having a nitrogen atom-containing group include, but are not limited to, hydrocarbon compounds containing an epoxy group bonded to an amino group, and may further contain an epoxy group bonded to an ether group.

[0257] Examples of such epoxy compounds include, but are not limited to, epoxy compounds represented by the following general formula (a).

[0258] [Chemistry 1]

[0259]

[0260] In the above formula (a), R is a hydrocarbon group having a valence of two or more, or a divalent or higher organic group having at least one polar group selected from polar groups having oxygen such as ether, epoxy, and ketone, polar groups having sulfur such as thioether and thioketone, and polar groups having nitrogen such as tertiary amino and imino groups.

[0261] The hydrocarbon group having a valence of two or more is a saturated or unsaturated linear, branched, or cyclic hydrocarbon group, and includes alkylene, alkenylene, and phenylene groups. Preferred hydrocarbon groups are those having 1 to 20 carbon atoms. Examples include methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-phenylene, m-phenylene, p-phenylene, m-xylene, p-xylene, and bis(phenylene)-methane.

[0262] In the above formula (a), R 1 、R 4 is a hydrocarbon group having 1 to 10 carbon atoms, R 1 、R 4 They can be the same or different from each other.

[0263] In the above formula (a), R 2 、R 5 is hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, R 2 、R 5 They can be the same or different from each other.

[0264] In the above formula (a), R 3 It is a hydrocarbon group having 1 to 10 carbon atoms, or a structure represented by the following formula (a1).

[0265] R 1 、R 2 、R 3 They may be in a ring structure formed by bonding with each other.

[0266] In addition, R 3 In the case of a hydrocarbon group, it may be a cyclic structure bonded to R. In the case of the above cyclic structure, it may be a cyclic structure bonded to R 3 The N and R are directly bonded.

[0267] In the above formula (a), n is an integer of 1 or greater, and m is an integer of 0 or 1 or greater.

[0268] [Chemistry 2]

[0269]

[0270] In the above formula (a1), R 1 、R 2 and R of the above formula (a) 1 、R 2 Similarly, R 1 、R 2 They may be the same as or different from each other.

[0271] As for the epoxy compound as the modifier having a nitrogen atom-containing group, a substance having a hydrocarbon group containing an epoxy group is preferred, and a substance having a hydrocarbon group containing a glycidyl group is more preferred.

[0272] The hydrocarbon group containing an epoxy group bonded to an amino group or an ether group is not particularly limited, and examples thereof include glycidylamino, diglycidylamino, and glycidyloxy groups. A more preferred molecular structure is an epoxy-containing compound having a glycidylamino or diglycidylamino group and a glycidyloxy group, for example, a compound represented by the following general formula (a2).

[0273] [Chemistry 3]

[0274]

[0275] In the above formula (a2), R is defined in the same manner as R in the above formula (a), and R 6 It is a hydrocarbon group having 1 to 10 carbon atoms or a structure represented by the following formula (a3).

[0276] R 6 When it is a hydrocarbon group, it can be bonded with R to form a ring structure. In this case, R 6 The bonded N and R are directly bonded.

[0277] In formula (a2), n is an integer of 1 or greater, and m is an integer of 0 or 1 or greater.

[0278] [Chemistry 4]

[0279]

[0280] As the epoxy compound as the modifier having a nitrogen atom-containing group, a compound having one or more diglycidylamino groups and one or more glycidoxy groups in the molecule is particularly preferred.

[0281] Examples of epoxy compounds used as a modifier having a nitrogen atom-containing group include, but are not limited to, N,N-diglycidyl-4-glycidyloxyaniline, 1-N,N-diglycidylaminomethyl-4-glycidyloxy-cyclohexane, 4-(4-glycidyloxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidyloxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidyloxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidyloxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl Oleyl m-xylenediamine, 4,4-methylene-bis(N,N-diglycidylaniline), 1,4-bis(N,N-diglycidylamino)cyclohexane, N,N,N',N'-tetraglycidyl p-phenylenediamine, 4,4'-bis(diglycidylamino)benzophenone, 4-(4-glycidylpiperazinyl)-(N,N-diglycidyl)aniline, 2-[2-(N,N-diglycidylamino)ethyl]-1-glycidylpyrrolidine, N,N-diglycidylaniline, 4,4'-diglycidyl-dibenzylmethylamine, N,N-diglycidylaniline, N,N-diglycidyl o-toluidine, N,N-diglycidylaminomethylcyclohexane, etc. Among these, particularly preferred ones include N,N-diglycidyl-4-glycidoxyaniline and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0282] From the aspect of effectively and surely giving play to the effect of the present embodiment, the modifier is preferably an alkoxysilane compound with a group containing nitrogen atoms. Such a modifier can be enumerated but is not limited to, for example, 3-dimethylaminopropyl trimethoxysilane, 3-dimethylaminopropyl methyl dimethoxysilane, 3-diethylaminopropyl triethoxysilane, 3-morpholinopropyl trimethoxysilane, 3-piperidinyl propyl triethoxysilane, 3-hexamethyleneiminopropyl methyl diethoxysilane, 3-(4-methyl-1-piperazinyl) propyl triethoxysilane, 1-[3-(triethoxysilyl)-propyl]-3-methylhexahydropyrimidine, 3-(4-trimethylsilyl-1-piperazinyl) propyl triethoxysilane. silane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 3-dimethylamino-2-(dimethylaminomethyl)propyltrimethoxysilane, bis(3-dimethoxymethylsilylpropyl)-N-methylamine, bis(3-trimethoxysilylpropyl)-N-methylamine, bis(3-triethoxysilylpropyl)methylamine, tris(trimethoxysilyl)amine, tris(3-trimethoxysilylpropyl)amine, N,N , N', N'-tetrakis (3-trimethoxysilylpropyl) ethylenediamine, 3-isocyanatopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxysilylpropyl)-1-aza-2-silacyclohexane methoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dimethoxy-8-(N,N-diethylamino)methyl-1,6-dioxa-2-silacyclooctane, etc.

[0283] As the alkoxysilane compound having a nitrogen atom-containing group, the following compounds can be given as particularly preferred examples.

[0284] Specific examples include tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-tripropoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (also referred to as "N,N,N',N'-tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine"), tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, and tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine. -[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-sila-2-azacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexanediamine, penta(3- trimethoxysilylpropyl)-diethylenetriamine, tris(3-trimethoxysilylpropyl)-methyl-1,3-propylenediamine, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-silacyclopentane)propyl]silane, 3 -Tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane, 1-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 1-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexyl-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl] ether, (3-trimethoxysilylpropyl) phosphate.

[0285] Other examples include bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)phosphate, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propaneamine, and N-(1,3-dimethylbutylidene)-3-(trimethoxysilyl)-1-propaneamine. , N-benzylidene-3-(triethoxysilyl)propane-1-amine, N-benzylidene-3-(trimethoxysilyl)propane-1-amine, 1,1-(1,4-phenylene)bis(N-(3(triethoxysilyl)propyl)methanamine), 1,1-(1,4-phenylene)bis(N-(3(trimethoxysilyl)propyl)methanamine), 2-methoxy-2-methyl-1-(benzylideneaminoethyl)-1-aza-2-silacyclopentane, and 2-methoxy-2-methyl-1-(4-methoxybenzylideneaminoethyl)-1-aza-2-silacyclopentane.

[0286] Further examples include 1-methyl-4-[3-(trimethoxysilyl)propyl]piperazine, 1-methyl-4-[3-(triethoxysilyl)propyl]piperazine, 1-methyl-4-[3-(methyldimethoxysilyl)propyl]piperazine, 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), -(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1-amine).

[0287] Further examples include 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylmethane-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylmethane-1-amine), ,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-diethylmethane-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethane-1-amine), 3,3'-(1,1 ,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dipropylmethane-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylmethane-1-amine), disiloxane-1,3-diyl)bis(N,N-dipropylmethane-1-amine), 1,3-bis(3-(1H-imidazol-1-yl)propyl)1,1,3,3-tetramethoxydisiloxane, 1,3-bis(3-(1H-imidazol-1-yl)propyl)-1,1,3,3-tetraethoxydisiloxane, and 1,3-bis(3-(1H-imidazol-1-yl)propyl)1,1,3,3-tetrapropoxydisiloxane.

[0288] Among the coupling modifiers having a nitrogen atom-containing group, examples of protected amine compounds in which active hydrogen is substituted with a protecting group include compounds having an alkoxysilane and a protected amine in the molecule.

[0289] Examples of such compounds include, but are not limited to, N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane, N,N-bis(triethylsilyl)aminopropylmethyldiethoxysilane, 3-(4-trimethylsilyl-1-piperazinyl)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl)aminopropylmethyldiethoxysilane, 2,2-Dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane.

[0290] In addition, for example, N-(1,3-dimethylbutylidene)-3-methyl(dimethoxysilyl)-1-propaneamine, N-(1,3-dimethylbutylidene)-3-methyl(diethoxysilyl)-1-propaneamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propaneamine, N-(1-methylethylidene)-3-(trimethoxysilyl)-1-propaneamine, N-(1-methylethylidene)-3-methyl(dimethoxysilyl)-1-propaneamine, N-(1-methylethylidene)-3-methyl(diethoxysilyl)-1-propaneamine, N-ethylidene-3-(triethoxysilyl)-1-propaneamine, )-1-propaneamine, N-ethylidene-3-(trimethoxysilyl)-1-propaneamine, N-ethylidene-3-methyl(dimethoxysilyl)-1-propaneamine, N-ethylidene-3-methyl(diethoxysilyl)-1-propaneamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propaneamine, N-(1-methylpropylidene)-3-(trimethoxysilyl)-1-propaneamine, N-(1-methylpropylidene)-3-methyl(dimethoxysilyl)-1-propaneamine, N-(1-methylpropylidene)-3-methyl(diethoxysilyl)-1-propaneamine, N-benzylidene-3-methyl( 1-amine, N-benzylidene-3-methyl(diethoxysilyl)propane-1-amine, N-4-methylbenzylidene-3-(triethoxysilyl)propane-1-amine, N-4-methylbenzylidene-3-(trimethoxysilyl)propane-1-amine, N-4-methylbenzylidene-3-methyl(dimethoxysilyl)propane-1-amine, N-4-methylbenzylidene-3-methyl(diethoxysilyl)propane-1-amine, N-naphthylene-3-(trimethoxysilyl)propane-1-amine, N-naphthylene-3-methyl(dimethyl)propane-1-amine, N-naphthylene-3-methyl(triethoxysilyl)propane-1-amine, N-naphthylene-3-methyl(dimethyl)propane-1-amine 1-(trimethylsilyl)propyl)piperazine, 1-trimethylsilyl-4-[3-(triethoxysilyl)propyl]piperazine.

[0291] In the production process of the conjugated diene polymer of this embodiment, when a coupling step is performed, it is further preferred to use a modifier having a nitrogen-containing group represented by any of the following formulas (A) to (D) in the coupling step. These modifiers may be used alone or in combination of two or more.

[0292] [Chemistry 5]

[0293]

[0294] Here, R 10 、R 11 is a hydrocarbon group having 1 to 12 carbon atoms, may have an unsaturated bond, and may be the same or different. 12 It is a hydrocarbon group having 1 to 20 carbon atoms.

[0295] R 8 、R 9 The aliphatic hydrocarbon groups have 1 to 6 carbon atoms, may have an unsaturated bond, and may be the same or different.

[0296] R 7 It is a hydrocarbon group having 1 to 20 carbon atoms, containing Si, O or N, and optionally substituted with an organic group having no active hydrogen, and may have an unsaturated bond.

[0297] a is an integer from 1 to 3.

[0298] [Chemistry 6]

[0299]

[0300] In the above formula (B), A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of oxygen, nitrogen, silicon, sulfur, and phosphorus atoms and having no active hydrogen.

[0301] R 13 、R 14 and R 15 Each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms.

[0302] R 16 、R 17 、R 18 、R 19 and R 21 Each independently represents an alkyl group having 1 to 20 carbon atoms.

[0303] R 20 and R 22 Each independently represents an alkylene group having 1 to 20 carbon atoms.

[0304] R23 Each independently represents an alkyl group having 1 to 20 carbon atoms or a trialkylsilyl group.

[0305] b each independently represents an integer of 1 to 3, c each independently represents 1 or 2, i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, and the sum of i, j and k is an integer of 4 to 10.

[0306] [Chemistry 7]

[0307]

[0308] Among them, in formula (C), R 24 、R 25 、R 26 、R 27 、R 28 and R 29 Each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms.

[0309] R 30 、R 31 and R 32 Each independently represents an alkylene group having 1 to 20 carbon atoms.

[0310] s, t, and u each independently represent an integer of 1 to 3, and the sum of s, t, and u is an integer of 4 or greater.

[0311] [Chemistry 8]

[0312]

[0313] Among them, in formula (D), B 1 and B 2 Each independently represents a divalent hydrocarbon group having 1 to 20 carbon atoms which may contain an oxygen atom.

[0314] R 33 ~R 36 Each independently represents a monovalent hydrocarbon group having 1 to 20 carbon atoms. 1 ~L 4 Each independently represents a divalent, trivalent or tetravalent alkylsilyl group substituted with an alkyl group having 1 to 10 carbon atoms, or a monovalent hydrocarbon group having 1 to 20 carbon atoms, or L 1 and L 2 , and L 3 and L 4 can be linked to each other to form a ring with 1 to 5 carbon atoms, L 1 and L 2 , and L 3 and L 4When the ions are linked to each other to form a ring, the formed ring may contain one to three or more heteroatoms selected from the group consisting of N, O, and S.

[0315] Specifically, in the above formula (D), B 1 and B 2 Each independently represents an alkylene group with 1 to 10 members, R 33 ~R 36 are each independently an alkyl group having 1 to 10 carbon atoms, L 1 ~L 4 Each independently represents a tetravalent alkylsilyl group substituted with an alkyl group having 1 to 5 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or L 1 and L 2 , and L 3 and L 4 can be linked to each other to form a ring with 1 to 3 carbon atoms, L 1 and L 2 , and L 3 and L 4 When the ions are linked to each other to form a ring, the formed ring may contain one to three or more heteroatoms selected from the group consisting of N, O, and S.

[0316] Examples of the coupling modifier represented by the above formula (A) include, but are not limited to, 1-methyl-4-[3-(trimethoxysilyl)propyl]piperazine, 1-methyl-4-[3-(triethoxysilyl)propyl]piperazine, 1-propyl-4-[3-(trimethoxysilyl)propyl]piperazine, 1-propyl-4-[3-(triethoxysilyl)propyl]piperazine, 1-trimethylsilyl-4-[3-(trimethoxysilyl)propyl]piperazine, and 1-trimethylsilyl-4-[3-(triethoxysilyl)propyl]piperazine.

[0317] Among these, a in the above formula (A) is preferably 3 from the viewpoint of improving the reactivity and interaction between the conjugated diene polymer of the present embodiment and an inorganic filler such as silica, and from the viewpoint of improving processability.

[0318] The reaction temperature and reaction time in the coupling step using the coupling modifier represented by the above formula (A) are not particularly limited, but are preferably 0° C. to 120° C. for 30 seconds or longer.

[0319] Regarding the amount of the coupling modifier represented by formula (A) added, the total molar number of the alkoxy groups bonded to the silyl group in the compound represented by formula (A) is preferably in the range of 0.2 to 2.0 times the molar number of the polymerization initiator added, more preferably in the range of 0.3 to 1.5 times, and even more preferably in the range of 0.4 to 1.0 times. From the perspective of achieving a more preferred molecular weight range for the resulting modified conjugated diene polymer, the amount is preferably 0.2 times or more, and from the perspective of long-term storage stability, the amount is preferably 2.0 times or less.

[0320] More specifically, the addition amounts of the polymerization initiator and the coupling modifier represented by the above formula (A) can be adjusted so that the molar number of the coupling modifier represented by the above formula (A) is preferably 0.1 times or more and 1.0 times or less relative to the molar number of the polymerization initiator.

[0321] In the above formula (B), A is preferably represented by any one of the following formulae (Formula I) to (Formula IV).

[0322] [Chemistry 9]

[0323]

[0324] In the above formula (Chemical I), D 1 represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. h represents an integer from 1 to 10. When there are plural D 1 Each one is independent.

[0325] [Chemistry 10]

[0326]

[0327] In the above formula (II), D 2 represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. 3 represents an alkyl group having 1 to 20 carbon atoms, and h represents an integer of 1 to 10. When there are plural D 2 and D 3 Each one is independent.

[0328] [Chemistry 11]

[0329]

[0330] In the above formula (III), D 4 represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. h represents an integer from 1 to 10. When there are plural D 4 Each one is independent.

[0331] [Chemistry 12]

[0332]

[0333] In the above formula (IV), D 5 represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. h represents an integer from 1 to 10. When there are plural D 5 Each one is independent.

[0334] When A in the above formula (B) is represented by formula (I), the coupling modifier may be, for example, but not limited to, tris(3-trimethoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)amine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-ethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)amine, Diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)amine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-propanediamine.

[0335] Other examples include tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propylenediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-silacyclopentane)propyl]-1,3-propylenediamine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-silacyclopentane)propyl]-1,3-propylenediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propylenediamine, 1,3-propylenediamine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propylenediamine, tetrakis(3-triethoxysilylpropyl)-1,3-propylenediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propylenediamine.

[0336] Further examples include bis(3-triethoxysilylpropyl)-bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propylenediamine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-1,3-propylenediamine, tetrakis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propylenediamine, tris(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propylenediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]- -2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane.

[0337] Further examples include tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propylenediamine, tris(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane Bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane.

[0338] Further examples include tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-triethoxysilylpropyl)-1,3-propylenediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3- Tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-1,3-propanediamine, tetrakis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(1-ethoxy-2 -trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl) -[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexanediamine, and penta(3-trimethoxysilylpropyl)-diethylenetriamine.

[0339] When A in the above formula (B) is represented by formula (II), the coupling modifier may be, but is not limited to, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, bis(2-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, 1,3-propanediamine, bis(2-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-methyl-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)-methyl-1,3-propanediamine, N 1 ,N 1 '-(Propane-1,3-diyl)bis(N 1 -methyl-N 3 ,N 3 -bis(3-(trimethoxysilyl)propyl)-1,3-propylenediamine), and N 1 -(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N 1 -methyl-N 3 -(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N 3 -(3-(trimethoxysilyl)propyl)-1,3-propanediamine.

[0340] When A in the above formula (B) is represented by formula (III), the coupling modifier may be, but is not limited to, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]- [3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, (3-trimethoxysilyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane alkyl)propyl] silane, bis[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl] silane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl] silane, bis(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl- 1-sila-2-azacyclopentane)propyl]-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-bis(3-trimethoxysilylpropyl)silane, and bis(3-trimethoxysilylpropyl)-bis[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]silane.

[0341] When A in the above formula (B) is represented by formula (IV), the coupling modifier may be, but is not limited to, 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-(2,2-dimethoxy-1-aza-2-silacyclopentane)propane and 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane.

[0342] The amount of the modifier represented by formula (B) is preferably determined based on the ratio of the number of moles of polymerization initiator added to the number of moles of the modifier represented by formula (B). This allows the conjugated diene polymer and the modifier to react in a desired stoichiometric ratio.

[0343] More specifically, the amount of the polymerization initiator and the coupling modifier represented by formula (B) can be adjusted so that the number of moles of the coupling modifier represented by the above formula (B) is preferably 0.012 times or more and 1.0 times or less, more preferably 0.02 times or more and 0.5 times or less relative to the number of moles of the polymerization initiator. In this case, in the above formula (B), the number of functional groups of the modifier (for example, when i and j are 2 or more, w and x are present in multiple numbers, these f and g are equal when they are f×i+(g+1)×j+k) is preferably an integer of 5 to 10, more preferably an integer of 6 to 10. From the perspective of making the molecular weight of the modified conjugated diene polymer obtained into the preferred range, it is preferably 0.012 times or more. In addition, from the perspective of storage stability during long-term storage, it is preferably 0.2 times or less.

[0344] Among these, it is preferred that i, j, and k in the above formula (B) are all 3 from the viewpoint of improving the reactivity and interaction between the modified conjugated diene polymer and an inorganic filler such as silica, and from the viewpoint of improving processability.

[0345] Examples of the coupling modifier represented by the above formula (C) include, but are not limited to, tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl)amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, and tris(4-trimethoxysilylbutyl)amine.

[0346] The reaction temperature and reaction time in the coupling step using the coupling modifier represented by the above formula (C) are preferably, but not limited to, 0° C. to 120° C. for 30 seconds or longer.

[0347] Regarding the addition amount of the coupling modifier represented by the above formula (C), the total molar number of the alkoxy group bonded to the silyl group in the compound represented by the above formula (C) is preferably in the range of 0.1 times to 2.0 times the added molar number of the polymerization initiator, more preferably in the range of 0.2 times to 1.0 times, and further preferably in the range of 0.3 times to 0.5 times. From the perspective of the molecular weight of the modified conjugated diene polymer obtained, it is preferably 0.1 times or more. In addition, from the perspective of storage stability during long-term storage, it is preferably 2.0 times or less.

[0348] Examples of the coupling modifier represented by the formula (D) include 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3'-1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropane-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N- dimethylpropane-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropane-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropane-1-amine), etc.

[0349] The reaction temperature and reaction time in the coupling step using the coupling modifier represented by the above formula (D) are not particularly limited, but are preferably 0° C. to 120° C. for 30 seconds or more.

[0350] Regarding the amount of the coupling modifier represented by formula (D) added, the total molar number of the alkoxy groups bonded to the silyl group in the compound represented by formula (D) is preferably in the range of 0.25 to 2.0 times the molar number of the polymerization initiator added, more preferably in the range of 0.3 to 1 times, and even more preferably in the range of 0.35 to 0.5 times. From the perspective of the molecular weight of the resulting modified conjugated diene polymer and from the perspective of storage stability during long-term storage, it is preferably 2.0 times or less.

[0351] The method for producing the conjugated diene polymer of the present embodiment may include a condensation reaction step of causing a condensation reaction by adding a condensation accelerator after the coupling step and / or before the coupling step.

[0352] In the method for producing the conjugated diene polymer of the present embodiment, a deactivator and / or a neutralizer may be added to the polymer solution after the coupling step, if necessary.

[0353] Examples of the deactivating agent include, but are not limited to, water and alcohols such as methanol, ethanol, and isopropanol.

[0354] Examples of the neutralizing agent include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and neodecanoic acid (a mixture of multi-branched carboxylic acids having 9 to 11 carbon atoms, with a main component being a substance having 10 carbon atoms), aqueous solutions of inorganic acids, and carbon dioxide.

[0355] From the viewpoint of preventing gel formation after polymerization and improving stability during processing, it is preferred that a rubber stabilizer be added to the conjugated diene polymer of the present embodiment.

[0356] As the rubber stabilizer, known substances may be used but are not limited thereto. For example, antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl 3-(4'-hydroxy-3',5'-di-tert-butylphenol) propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol are preferred.

[0357] (Process of obtaining from polymer solution)

[0358] The method for producing the conjugated diene polymer of the present embodiment may include a step of obtaining the obtained conjugated diene polymer from the polymer solution. As a method for obtaining the conjugated diene polymer from the polymer solution, a known method may be used, for example, the following method may be used. The following methods may be mentioned: a method of separating the solvent by steam stripping, filtering out the conjugated diene polymer, and further dehydrating and drying the conjugated diene polymer to obtain the conjugated diene polymer; a method of concentrating the conjugated diene polymer by using a flash tank, and further devolatilizing the conjugated diene polymer by using a venting extruder, etc.; and a method of directly devolatilizing the conjugated diene polymer by using a rotary drum dryer, etc.; etc.

[0359] (Step of Obtaining Oil-Extended Conjugated Diene Polymer)

[0360] In the method for producing a conjugated diene polymer of the present embodiment, at least one selected from the group consisting of extender oil, liquid rubber, and resin may be further added to the produced conjugated diene polymer to produce an oil-extended conjugated diene polymer.

[0361] The oil-extended conjugated diene polymer includes not only oil-containing conjugated diene polymers but also oil-extended conjugated diene polymers containing liquid polybutadiene or various resins other than oil.

[0362] This can further improve the processability of the conjugated diene polymer.

[0363] As a method for adding the extender oil to the conjugated diene polymer, a method of adding the extender oil to the conjugated diene polymer solution and mixing the mixture to prepare an oil-extended polymer solution, followed by desolvation of the oil-extended polymer solution, is preferred but not limited to.

[0364] Examples of the extender oil include aromatic oils, naphthenic oils, paraffinic oils, and vegetable oils. The vegetable oil can be selected from the group consisting of linseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, castor oil, tung oil, pine root oil, sunflower oil, coconut oil, olive oil, coconut oil, peanut oil, and grapeseed oil. Among these, alternative aromatic oils having a polycyclic aromatic (PCA) content of 3% by mass or less based on the IP346 method are preferred from the perspectives of environmental safety, oil leakage prevention, and wet grip properties.

[0365] As alternative aromatic oils, for example, TDAE (Treated Distillate Aromatic Extracts) and MES (Mild Extraction Solvate) described in Kautschuk Gummi Kunststoffe 52 (12) 799 (1999) and RAE (Residual Aromatic Extracts) can be mentioned.

[0366] Examples of the liquid rubber include, but are not limited to, liquid polybutadiene and liquid styrene-butadiene rubber.

[0367] Examples of the resin include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including tung oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenol resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, oligomers of monoolefins, oligomers of diolefins, hydrogenated aromatic hydrocarbon resins, cyclic aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrogenated tung oil resins, hydrogenated oleoresins, and esters of hydrogenated oleoresins with monofunctional or polyfunctional alcohols.

[0368] These resins may be used alone or in combination of two or more.

[0369] When hydrogenation is performed, all unsaturated groups may be hydrogenated or some may remain.

[0370] The amount of at least one member selected from the group consisting of extender oil, liquid rubber, and resin is not particularly limited, but is preferably 1 to 60 parts by mass, more preferably 10 to 60 parts by mass, and even more preferably 15 to 37.5 parts by mass relative to 100 parts by mass of the conjugated diene polymer of this embodiment.

[0371] [Rubber composition]

[0372] The conjugated diene polymer of the present embodiment may be prepared into a rubber composition (hereinafter sometimes referred to as the rubber composition of the present embodiment) by adding a filler.

[0373] The rubber composition of the present embodiment includes a rubber component containing the conjugated diene polymer of the present embodiment described above, and a filler in an amount of 5.0 to 150 parts by mass relative to 100 parts by mass of the rubber component. The rubber component preferably includes 10 or more parts by mass of the conjugated diene polymer of the present embodiment relative to 100 parts by mass of the total amount of the rubber component. By dispersing the filler in the rubber component containing the conjugated diene polymer of the present embodiment, a rubber composition having better processability during vulcanization and better low hysteresis loss, fracture characteristics, and wear resistance of its sulfide can be obtained. In addition, by including the conjugated diene polymer of the present embodiment in the rubber component at a specified ratio, processability and wear resistance are further improved.

[0374] Examples of fillers include, but are not limited to, silicon oxide-based inorganic fillers, carbon black, metal oxides, and metal hydroxides. Among these, silicon oxide-based inorganic fillers are preferred. In particular, when the rubber composition is used for tires, anti-vibration rubber, and other automotive parts, or for vulcanized rubber applications such as shoes, it is particularly preferred to include a silicon oxide-based inorganic filler. Such fillers may be used alone or in combination of two or more.

[0375] The silicon oxide-based inorganic filler is not particularly limited, and known materials can be used. Preferably, the filler comprises solid particles containing SiO2 or Si3Al as a structural unit, and more preferably, solid particles containing SiO2 or Si3Al as a main component of the structural unit. Here, the main component refers to a component that accounts for more than 50% by mass, preferably 70% by mass or more, and more preferably 80% by mass or more of the silicon oxide-based inorganic filler.

[0376] As silicon oxide-based inorganic filler, it is possible to enumerate but not be limited to inorganic fibrous materials such as silicon oxide, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite and glass fiber. In addition, it is also possible to use a mixture of inorganic fillers other than silicon oxide-based inorganic fillers and silicon oxide-based inorganic fillers whose surface has been hydrophobized. Among these, from the aspect of further improving the intensity and the wear resistance of the rubber composition of the present embodiment, preferably silicon oxide or glass fiber, more preferably silicon oxide. As silicon oxide, it is not particularly limited, for example, dry silicon oxide, wet silicon oxide and synthetic silicate silicon oxide can be enumerated. In these silicon oxides, from the aspect of further improving the breaking strength of the rubber composition, preferably wet silicon oxide.

[0377] In order to more reliably obtain a rubber composition having practically good wear resistance and breaking strength, the nitrogen adsorption specific surface area of the silica-based inorganic filler determined by the BET adsorption method is preferably 100 m 2 / g above 300m 2 / g or less, more preferably 170m 2 / g above 250m 2 / g or less. In addition, the specific surface area can be smaller (for example, the specific surface area is less than 200m 2 / g) of silicon oxide inorganic fillers and larger specific surface area (e.g. 200m 2 / g or more) of silicon oxide inorganic filler. Especially when using a large specific surface area (e.g. 200m 2 In the case of a silica-based inorganic filler containing 100 g of silica or more, the rubber composition of this embodiment further improves the dispersibility of silica. As a result, a rubber composition having even better wear resistance, breaking strength, and low hysteresis loss tends to be obtained.

[0378] Examples of carbon black include, but are not limited to, various grades of carbon black such as SRF, FEF, HAF, ISAF, and SAF. Of these, carbon black having a nitrogen adsorption specific surface area of 50 m2 as determined by the BET adsorption method is preferred. 2 / g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or less.

[0379] As a metal oxide, as long as the chemical formula M x O y (M represents a metal atom, and x and y each independently represent an integer of 1 to 6.) The solid particles serving as the main component of the structural unit are not particularly limited, and examples thereof include aluminum oxide, titanium oxide, magnesium oxide, and zinc oxide.

[0380] The metal hydroxide is not particularly limited, and examples thereof include aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0381] The filler content in the rubber composition of this embodiment is preferably 5.0 parts by mass to 150 parts by mass, more preferably 20 parts by mass to 100 parts by mass, and even more preferably 30 parts by mass to 90 parts by mass, relative to 100 parts by mass of the rubber component. By ensuring that the filler content falls within the above range, the rubber composition tends to exhibit improved processability during vulcanization, and its vulcanized product tends to exhibit improved low hysteresis loss, fracture characteristics, and wear resistance.

[0382] In the rubber composition of this embodiment, from the perspective of reliably imparting properties required for applications such as tires, such as dry grip performance and electrical conductivity, it is preferred that 0.5 parts by mass to 100 parts by mass of carbon black be included per 100 parts by mass of the rubber component comprising the conjugated diene polymer of this embodiment. From the same perspective, the rubber composition more preferably includes 3.0 parts by mass to 100 parts by mass, and even more preferably 5.0 parts by mass to 50 parts by mass of carbon black per 100 parts by mass of the rubber component comprising the conjugated diene polymer of this embodiment.

[0383] The rubber composition of this embodiment may further contain a silane coupling agent. By making the rubber composition contain a silane coupling agent, the interaction between the rubber component and the filler can be further enhanced.

[0384] Silane coupling agents are preferably, but not limited to, compounds having a sulfur-bonding moiety and an alkoxysilyl or silanol moiety in one molecule. Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0385] In the rubber composition of the present embodiment, the content of the silane coupling agent is preferably from 0.1 to 30 parts by mass, more preferably from 0.5 to 20 parts by mass, and even more preferably from 1.0 to 15 parts by mass, relative to 100 parts by mass of the filler. When the content of the silane coupling agent is within the above range, the interaction between the rubber component and the filler tends to be further enhanced.

[0386] The rubber composition of the present embodiment may contain, as a rubber component, a rubbery polymer other than the conjugated diene polymer of the present embodiment (hereinafter simply referred to as a "rubbery polymer").

[0387] Examples of rubbery polymers include, but are not limited to, conjugated diene polymers and hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds and hydrogenated products thereof, block copolymers of conjugated diene compounds and vinyl aromatic compounds and hydrogenated products thereof, non-diene polymers, and natural rubber.

[0388] Examples of the rubbery polymer include, but are not limited to, styrene-based elastomers such as butadiene rubber and its hydrogenates, isoprene rubber and its hydrogenates, styrene-butadiene rubber and its hydrogenates, styrene-butadiene block copolymers and their hydrogenates, and styrene-isoprene block copolymers and their hydrogenates, and acrylonitrile-butadiene rubber and its hydrogenates.

[0389] Examples of non-diene polymers include, but are not limited to, olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber; butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0390] Examples of natural rubber include, but are not limited to, smoked sheet rubbers RSS Nos. 3 to 5, SMR, and epoxidized natural rubber.

[0391] The rubbery polymer may be a modified rubber to which a polar functional group such as a hydroxyl group or an amino group is added. When the rubber composition of the present embodiment is used for tire applications, the rubbery polymer is preferably one or more selected from the group consisting of butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber.

[0392] From the perspective of balancing the wear resistance, breaking strength, low hysteresis loss, and processability of the rubber composition, the mass average molecular weight of the rubber-like polymer is preferably from 2,000 to 2,000,000, and more preferably from 5,000 to 1,500,000. Furthermore, low-molecular-weight rubber-like polymers, i.e., so-called liquid rubbers, may also be used as the rubber-like polymer. These rubber-like polymers may be used alone or in combination of two or more.

[0393] In the case where the rubber composition of the present embodiment further includes the above-mentioned rubber-like polymer in addition to the conjugated diene polymer of the present embodiment, the content ratio (mass ratio) of the conjugated diene polymer relative to the rubber-like polymer, i.e., (conjugated diene polymer / rubber-like polymer), is preferably 10 / 90 or more and 100 / 0 or less, more preferably 20 / 80 or more and 90 / 10 or less, and further preferably 30 / 70 or more and 80 / 20 or less. That is, in the rubber component, relative to 100 parts by mass of the total amount of the rubber component, the conjugated diene polymer of the present embodiment preferably includes 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 90 parts by mass or less, and further preferably 30 parts by mass or more and 80 parts by mass or less. When the ratio of the conjugated diene polymer of the present embodiment contained in the rubber component is within the above range, the wear resistance and low hysteresis loss properties of the sulfide of the rubber composition tend to be more excellent.

[0394] To further improve the processability of the rubber composition of the present embodiment, a rubber softener may be added in addition to the rubber component.

[0395] As the rubber softener, the same ones as those exemplified as the rubber softener contained in the conjugated diene polymer can be used, and mineral oil or a liquid or low-molecular weight synthetic softener is suitable.

[0396] Mineral oil-based rubber softeners, known as process oils or extender oils, are used to soften, expand, and improve processability of rubber components. These are mixtures of aromatic, cycloalkane, and paraffin chains. Paraffins are defined as those in which at least 50% of the total carbon atoms belong to paraffin chains, cycloalkanes are defined as those in which at least 30% but no more than 45% of the total carbon atoms belong to cycloalkane rings, and aromatics are defined as those in which at least 30% of the total carbon atoms belong to aromatic carbon atoms. The rubber composition of this embodiment preferably contains a rubber softener with a moderate aromatic content. The inclusion of such a rubber softener further enhances compatibility with conjugated diene polymers.

[0397] The content of the rubber softener in the rubber composition of the present embodiment is represented by the total amount of the rubber softener previously added to the conjugated diene polymer or rubbery polymer and the rubber softener added when the rubber composition is prepared.

[0398] In the rubber composition of this embodiment, the content of the rubber softener is preferably from 0 parts by mass to 100 parts by mass, more preferably from 10 parts by mass to 90 parts by mass, and even more preferably from 30 parts by mass to 90 parts by mass, relative to 100 parts by mass of the rubber component. By setting the content of the rubber softener to 100 parts by mass or less relative to 100 parts by mass of the rubber component, bleed-out can be suppressed, further reducing stickiness on the surface of the rubber composition.

[0399] The rubber composition can be manufactured by mixing a conjugated diene polymer, a rubber-like polymer, a filler, a silane coupling agent, and a rubber softener. There is no particular limitation on the mixing method, and examples include melt mixing methods using common mixers such as an open mill, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder; and methods in which the components are dissolved and mixed and then heated to remove the solvent. Among these, melt mixing methods using a roller, a Banbury mixer, a kneader, or an extruder are preferred from the perspectives of productivity and good mixing properties. In addition, the rubber component, the filler, the silane coupling agent, and the additives can be mixed at one time or mixed multiple times.

[0400] The rubber composition of this embodiment can be made into a sulfide by vulcanization treatment using a vulcanizing agent. The vulcanizing agent is not particularly limited, and examples thereof include free radical initiators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur-containing compounds. Sulfur-containing compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and high-molecular-weight polysulfide compounds.

[0401] In the rubber composition of this embodiment, the content of the vulcanizing agent is preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass, per 100 parts by mass of the rubber component. Conventionally known methods can be used for vulcanization. Furthermore, the vulcanization temperature is preferably 120°C to 200°C, and more preferably 140°C to 180°C.

[0402] When vulcanizing the rubber composition, a vulcanization accelerator and / or a vulcanization aid may be used as needed. As the vulcanization accelerator, conventionally known materials may be used, and examples thereof include, but are not limited to, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators.

[0403] Examples of vulcanization aids include, but are not limited to, zinc white and stearic acid.

[0404] The content of the vulcanization accelerator and the vulcanization aid is preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass, respectively, per 100 parts by mass of the rubber component.

[0405] The rubber composition of this embodiment may contain various additives, including softeners other than those listed above, as well as other fillers, heat stabilizers, antistatic agents, weather stabilizers, anti-aging agents, colorants, and lubricants, to the extent that they do not impair the effects of this embodiment. As softeners, known softeners may be used. Other fillers include, but are not limited to, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. As heat stabilizers, antistatic agents, weather stabilizers, anti-aging agents, colorants, and lubricants, known materials may be used.

[0406] The rubber composition of this embodiment is suitable for use as a rubber composition for tires. The rubber composition of this embodiment is not particularly limited and can be used in various tires, such as fuel-efficient tires, all-season tires, high-performance tires, and studless tires, and in various tire parts, such as the tread, tire carcass, bead, and bead portion.

[0407] It should be noted that, unless otherwise specified, the numerical ranges described above as preferred ranges and the like can be replaced by numerical ranges formed by arbitrarily combining the values described as upper limits and the values described as lower limits.

[0408] Example

[0409] The present embodiment will be described in further detail below with reference to specific examples and comparative examples. However, the present invention is not limited to the following examples and comparative examples.

[0410] Various physical properties in Examples and Comparative Examples were measured by the methods shown below.

[0411] ((Physical Property 1) Polymer Segment Ratio)

[0412] <Solid content>

[0413] The solid content of the conjugated diene polymer solution is calculated based on the amount of nonvolatile components in the conjugated diene polymer solution flowing through the measurement point per unit time. The total amount of conjugated diene polymer solution flowing through the measurement point is collected over 3 minutes, and a polymerization terminator is immediately added. The sample is then transferred to a heat-resistant dish and dried in an oven at 140°C for at least 30 minutes. The remaining solid mass (M) is then measured.

[0414] Here, the solid content (m) is calculated from the following formula (I).

[0415] [Number 7]

[0416] Solid content m[g / min] = mass of solid matter M[g / 3min] ÷ 3…(I)

[0417] The measurement points were set as the discharge portion of the polymerization step (P1) for synthesizing the first polymer segment and the discharge portion of the polymerization step (P2) for forming the second polymer segment, and the solid amounts therein were designated as m1 and m2, respectively.

[0418] <Mass Ratio r1, r2 of the First and Second Polymer Segments>

[0419] The mass ratio r of each of the first polymer segment and the second polymer segment is determined, as shown in the following formula (II) and formula (III), from the solid amounts m1 and m2 of the discharge portions of the polymerization step (P1) for synthesizing the above-mentioned first polymer segment and the polymerization step (P2) for forming the above-mentioned second polymer segment, respectively, relative to the sum of the mass (U) of the conjugated diene compound and the mass (V) of the aromatic vinyl compound added per unit time in the entire polymerization step.

[0420] In this embodiment, U is the total amount of 1,3-butadiene added by the first and second stations per unit time, and V is the total amount of styrene added by the first and second stations per unit time.

[0421] [Number 8]

[0422]

[0423] <Polymer segment ratio: R>

[0424] The ratio of the mass ratio of the first polymer segment to the mass ratio of the second polymer segment: R (= r1 / r2) is calculated by the following formula (IV).

[0425] [Number 9]

[0426] The mass ratio of polymer segments R = r1 / r2 (IV)

[0427] ((Physical Property 2) Amount of Bonded Aromatic Vinyl Monomer Units (Amount of Bonded Styrene))

[0428] <bonded styrene amount of conjugated diene polymer X all >

[0429] A conjugated diene polymer containing no rubber softener and collected from the discharge portion of the polymerization step (P2) for forming the second polymer segment was used as a sample. 100 mg of the sample was dissolved in chloroform to a volume of 100 mL to prepare a measurement sample.

[0430] The amount of bonded styrene (mass %) relative to 100 mass % of the coupled conjugated diene polymer sample was measured based on the absorption of the phenyl group of styrene at an ultraviolet absorption wavelength (near 254 nm) (measuring apparatus: spectrophotometer "UV-2450" manufactured by Shimadzu Corporation).

[0431] <Amount of Bonded Styrene in the First Polymer Segment X1>

[0432] The sample was replaced with the solid content of the polymer solution discharged from the polymerization step (P1) for synthesizing the first polymer segment, instead of the conjugated diene polymer. Regarding other conditions, the bound styrene amount was calculated using the same method as the bound styrene amount in the conjugated diene polymer segment.

[0433] <Amount of Bonded Styrene in the Second Polymer Segment X2>

[0434] The solid amounts m1 and m2, the bonded styrene amounts X1 and X2 in the polymerization step (P1) for synthesizing the first polymer segment and the polymerization step (P2) for forming the second polymer segment are respectively obtained. all, the amount of bonded styrene (X2) in the second polymer segment is calculated by the following formula (VIII).

[0435] [Number 10]

[0436]

[0437] <Difference in the amount of bonded styrene between the first polymer segment and the second polymer segment |ΔX|>

[0438] The difference |ΔX| between the amount of bonded styrene in the first polymer segment and the amount in the second polymer segment was determined by the following formula (IX).

[0439] [Number 11]

[0440] |△X|=|X2-X1| (IX)

[0441] ((Physical Property 3) Amount of Vinyl Bonds in the Bonded Conjugated Diene (Amount of 1,2-Vinyl Bonds in the Bonded Butadiene))

[0442] <Vinyl bond amount Y of conjugated diene polymer all >

[0443] A conjugated diene polymer containing no rubber softener and collected from the discharge portion of the polymerization step (P2) for forming the second polymer segment was used as a sample. 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample.

[0444] At 600~1000cm -1 The infrared spectrum of each sample was measured using a Fourier transform infrared spectrophotometer (trade name "FT-IR230" manufactured by JASCO Corporation) within the range of .

[0445] The amount (mol %) of 1,2-vinyl bonds in the bonded butadiene was determined from the absorbance at a predetermined wave number according to the Hampton method (RR Hampton, Analytical Chemistry 21, 923 (1949)).

[0446] <Vinyl Bond Amount Y1 in the First Polymer Segment>

[0447] The sample was replaced with the solid content of the polymer solution discharged from the polymerization step (P1) for synthesizing the first polymer segment, instead of the conjugated diene polymer. The vinyl bond content was calculated using the same method as for the conjugated diene polymer under other conditions.

[0448] <Vinyl Bond Amount Y2 in the Second Polymer Segment>

[0449] The solid contents m1 and m2 in the polymerization step (P1) for synthesizing the first polymer segment and the polymerization step (P2) for forming the second polymer segment, the vinyl bond contents Y1 and Y2 in the bonded conjugated diene, and the all , the vinyl bond content in the second polymer segment was calculated by the following formula (X).

[0450] [Number 12]

[0451]

[0452] <Difference ΔY between the Vinyl Bond Amounts of the First and Second Polymer Segments>

[0453] The difference ΔY between the amount of vinyl bonds in the conjugated dienes bonded to the first polymer segment and the second polymer segment was determined by the following formula (XI).

[0454] [Number 13]

[0455] △Y=Y2-Y1 (XI)

[0456] ((Physical Property 4) Conversion Rate, Polymerization Conversion Rate Difference)

[0457] The conversion rate c of the conjugated diene compound in the polymerization step (P1) for synthesizing the first polymer segment was calculated from the following formula (V) and formula (VI): bd , and the conversion rate of aromatic vinyl compounds c st .

[0458] [Number 14]

[0459]

[0460] In addition, the difference between the conversion rate of the conjugated diene compound and the conversion rate of the aromatic vinyl compound was calculated from the following formula (VII): dif .

[0461] [Number 15]

[0462] c dif [%] = |c bd [%] -c st [%]| (VII)

[0463] ((Physical Property 5) Estimated Glass Transition Temperature)

[0464] The estimated glass transition temperature of the conjugated diene polymer is determined using the above formula (iii).

[0465] ((Physical Property 6) Molecular Weight)

[0466] The conjugated diene polymers of the Examples and Comparative Examples were used as samples. A GPC measuring apparatus (manufactured by Tosoh Corporation, trade name "HLC-8320GPC") connected to three columns using a polystyrene gel as a filler was used to measure the chromatogram using an RI detector (manufactured by Tosoh Corporation, trade name "HLC8020"). The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were determined based on a calibration curve obtained using standard polystyrene.

[0467] The eluent used was THF (tetrahydrofuran) added with 5 mmol / L triethylamine. Three columns, trade name "TSKgel SuperMultiporeHZ-H" manufactured by Tosoh Corporation, were connected, and a trade name "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation was connected to the column as a guard column.

[0468] 10 mg of a sample for measurement was dissolved in 10 mL of THF to prepare a measurement solution. 10 μL of the measurement solution was injected into a GPC measurement apparatus and measurement was performed under the conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL / min.

[0469] ((Physical Property 7) Polymer Mooney Viscosity)

[0470] The conjugated diene polymers of Examples and Comparative Examples were used as samples and the Mooney viscosity was measured using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) in accordance with ISO 289 using an L-shaped rotor at a measurement temperature of 100°C.

[0471] First, the sample was preheated at the test temperature for 1 minute, and then the rotor was rotated at 2 rpm. The torque after 4 minutes was measured and the value was taken as the Mooney viscosity (ML (1+4) ).

[0472] ((Physical Property 8) Glass Transition Temperature (Tg))

[0473] In the case where the conjugated diene polymers of the Examples and Comparative Examples were oil-extended, the conjugated diene polymers after the oil extension was extracted were used as samples. A DSC curve was recorded using a differential scanning calorimeter "DSC3200S" manufactured by Mac Science, Inc., in accordance with ISO 22768:2006, while the temperature was raised from -120°C to 40°C at a rate of 10°C / min under a flow of 50 mL / min of helium. The inflection point of the DSC observed in the range of -100°C to 20°C was defined as the glass transition temperature.

[0474] The extrapolated glass transition starting temperature is set to the temperature of the intersection of a straight line extending from the base line on the low temperature side to the high temperature side and a tangent line drawn at the point where the slope of the curve of the step-like change portion of the glass transition becomes maximum.

[0475] The extrapolated glass transition end temperature is defined as the temperature at the intersection of a straight line extending from the high temperature side base line toward the low temperature side and a tangent line drawn at a point where the slope of the curve of the step-like change portion of the glass transition becomes maximum.

[0476] ((Physical Property 9) Modification Rate)

[0477] The modification rates of the conjugated diene polymers of Examples and Comparative Examples were measured by column adsorption GPC as follows.

[0478] The measurement was performed using a conjugated diene polymer as a sample by utilizing the property that the modified basic polymer component is adsorbed by a GPC column filled with silica gel.

[0479] The modification rate was determined by measuring the adsorption amount on the silica column from the difference between the chromatograms of a sample solution containing the sample and low molecular weight internal standard polystyrene measured on a polystyrene column and the chromatogram measured on a silica column.

[0480] <Preparation of sample solution>:

[0481] 10 mg of a sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF (tetrahydrofuran) to prepare a sample solution.

[0482] <GPC measurement conditions using a polystyrene column>:

[0483] A Tosoh HLC-8320GPC was used, and THF containing 5 mmol / L triethylamine was used as the eluent. 10 μL of the sample solution was injected into the device, and a chromatogram was obtained using an RI detector at a column oven temperature of 40°C and a THF flow rate of 0.35 mL / min.

[0484] As the column, three "TSKgel SuperMultiporeHZ-H" manufactured by Tosoh Corporation were connected, and a "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation was connected upstream thereof as a guard column.

[0485] <GPC Measurement Conditions Using a Silica Column>

[0486] The GPC measurement was performed using a trade name "HLC-8320GPC" manufactured by Tosoh Corporation and an RI detector (trade name "HLC8020" manufactured by Tosoh Corporation).

[0487] Using THF as the eluent, 50 μL of the sample solution was injected into the apparatus, and a chromatogram was obtained under the conditions of a column oven temperature of 40° C. and a THF flow rate of 0.5 ml / min.

[0488] As columns, trade names "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S" manufactured by Agilent were connected in this order, and a trade name "DIOL 4.6×12.5 mm 5 micron" was connected upstream thereof as a guard column.

[0489] <Calculation method of modification rate>:

[0490] The overall peak area of the chromatogram using a polystyrene column is set to 100, the peak area of the sample is set to p1, the peak area of the standard polystyrene is set to p2, the overall peak area of the chromatogram using a silica column is set to 100, the peak area of the sample is set to p3, and the peak area of the standard polystyrene is set to p4, and the modification rate (%) is calculated by the following formula.

[0491] Modification rate (%) = [1 - (p2 × p3) / (p1 × p4)] × 100

[0492] (where p1+p2=p3+p4=100)

[0493] [Production of Conjugated Diene Polymer]

[0494] (Example 1)

[0495] Two tank-type pressure vessels equipped with a stirrer and a jacket for temperature control were connected as polymerization reactors. The tank-type pressure vessels had an internal volume of 10 L, a ratio (L / D) of internal height (L) to diameter (D) of 4.0, an inlet at the bottom, and an outlet at the top.

[0496] Using the first polymerization reactor, a polymerization step (P1) for synthesizing the first polymer segment is carried out. 1,3-butadiene, which has been previously dehydrated, is mixed at 20.3 g / min, styrene at 4.31 g / min, and n-hexane at 173 g / min. In a static mixer provided in the middle of the piping supplying the mixed solution to the inlet of the reactor, n-butyl lithium for inert treatment of residual impurities is added at 0.104 mmol / min and mixed, and then continuously supplied to the bottom of the reactor. 2,2-bis(2-tetrahydrofuryl)propane as a polar substance is further supplied at a rate of 0.0235 mmol / min, and n-butyl lithium as a polymerization initiator is supplied at a rate of 0.239 mmol / min to the bottom of the first reactor that is vigorously mixed using a stirrer, and the temperature inside the reactor is maintained at 78°C. After the polymerization reaction reached stability, the total amount of the conjugated diene polymer was discharged from the top of the reactor, an antioxidant (BHT) was added at 0.2 g per 100 g of the conjugated diene polymer, and the solvent was removed. The amount of bonded aromatic vinyl monomer units (X1) in the first polymer segment, the amount of vinyl bonds in the bonded conjugated diene (Y1), and the solid content concentration (m1) were then measured.

[0497] Next, a second polymerization reactor is used to carry out a step (P2) of forming a second polymer segment.

[0498] The conjugated diene polymer solution was continuously supplied from the top of the first reactor to the bottom of the second reactor. 1,3-Butadiene was added at a rate of 8.71 g / min, n-hexane was added at a rate of 32.1 g / min, and 2,2-bis(2-tetrahydrofuryl)propane as a polar substance was added at a rate of 0.450 mmol / min to the second reactor, and the reaction was continued at 78°C while stirring.

[0499] Next, as a modification step, tetrakis(3-trimethoxysilylpropyl)-1,3-propylenediamine ("Coupling Agent A" in the table below) and 1-methyl-4-[3-(trimethoxysilyl)propyl]piperazine ("Coupling Agent B" in the table below) were continuously added to the conjugated diene polymer solution flowing from the top of the second reactor at a rate of 0.0103 mmol / minute and 0.0965 mmol / minute, respectively. The solution was mixed using a static mixer to allow a coupling reaction to proceed. The time until the coupling agents were added to the polymer solution flowing from the reactor outlet was 4.8 minutes, and the temperature was 68°C.

[0500] The total amount of the conjugated diene polymer solution after the coupling reaction was discharged, and an antioxidant (BHT) was added so as to be 0.2 g per 100 g of the polymer. The solvent was removed, and the molecular weight and the amount of bonded aromatic vinyl groups (X all ) and the vinyl bond amount (Y all ), solid content concentration (m2), and glass transition temperature were measured.

[0501] Next, an antioxidant (BHT) was continuously added to the conjugated diene polymer solution after the coupling reaction at a rate of 0.055 g / min (n-hexane solution) so as to provide 0.2 g per 100 g of the polymer, thereby completing the coupling reaction.

[0502] Simultaneously with the antioxidant, 5.0 g of SRAE oil (JOMO Process NC140, manufactured by JX Nippon Mining and Petrochemical Corporation) was continuously added as a rubber softener per 100 g of the polymer and mixed using a static mixer. The solvent was removed by steam stripping to obtain the modified conjugated diene polymer of Example 1.

[0503] (Example 2)

[0504] A modified conjugated diene polymer of Example 2 was obtained in the same manner as in Example 1 except that the 1,3-butadiene supplied to the first reactor was changed to 18.7 g / min, the styrene was changed to 6.67 g / min, and the 1,3-butadiene added to the second reactor was changed to 8.00 g / min.

[0505] (Example 3)

[0506] A modified conjugated diene polymer of Example 3 was obtained in the same manner as in Example 1 except that the 1,3-butadiene supplied to the first reactor was changed to 17.3 g / min, the styrene was changed to 8.67 g / min, and the 1,3-butadiene added to the second reactor was changed to 7.40 g / min.

[0507] (Example 4)

[0508] A modified conjugated diene polymer of Example 4 was obtained in the same manner as in Example 1 except that the 1,3-butadiene supplied to the first reactor was changed to 21.0 g / min, the styrene was changed to 3.33 g / min, and the 1,3-butadiene added to the second reactor was changed to 9.00 g / min.

[0509] (Example 5)

[0510] A modified conjugated diene polymer of Example 5 was obtained in the same manner as in Example 1 except that the 1,3-butadiene supplied to the first reactor was changed to 21.9 g / min, the styrene was changed to 2.00 g / min, and the 1,3-butadiene added to the second reactor was changed to 9.40 g / min.

[0511] (Example 6)

[0512] The modified conjugated diene polymer of Example 6 was obtained in the same manner as in Example 1, except that the L / D of the first reactor was changed to 6.0, the styrene supplied to the first reactor was 3.88 g / min, the 2,2-bis(2-tetrahydrofuryl)propane as a polar substance was 0.0208 mmol / min, the n-butyllithium as a polymerization initiator was 0.208 mmol / min, the 2,2-bis(2-tetrahydrofuryl)propane supplied to the second reactor was 0.396 mmol / min, the coupling agent A added in the modification step was changed to 0.00917 mmol / min, the coupling agent B was changed to 0.0856 mmol / min, and styrene was newly added to the second reactor at a rate of 0.43 g / min.

[0513] (Example 7)

[0514] A modified conjugated diene polymer of Example 7 was obtained in the same manner as in Example 1 except that the 1,3-butadiene supplied to the first reactor was changed to 24.9 g / min, the styrene was changed to 4.35 g / min, and the 1,3-butadiene added to the second reactor was changed to 4.35 g / min.

[0515] (Example 8)

[0516] A modified conjugated diene polymer of Example 8 was obtained in the same manner as in Example 1, except that the 1,3-butadiene supplied to the first reactor was changed to 4.64 g / min, the styrene was changed to 0.46 g / min, the internal temperature of the first reactor was changed to 80° C., the 1,3-butadiene added to the second reactor was changed to 26.3 g / min, the temperature of the second polymerization reactor was changed to 82° C., and styrene was newly added to the second reactor at a rate of 1.98 g / min.

[0517] (Example 9)

[0518] The modified conjugated diene polymer of Example 9 was obtained in the same manner as in Example 1, except that the 1,3-butadiene supplied to the first reactor was changed to 19.5 g / min, the styrene supplied to the second reactor was changed to 2.66 g / min, the 1,3-butadiene added to the second reactor was changed to 10.5 g / min, 2,2-bis(2-tetrahydrofuryl)propane as a polar substance was added at 0.0177 mmol / min, and styrene was newly added to the second reactor at 0.67 g / min.

[0519] (Example 10)

[0520] A modified conjugated diene polymer of Example 10 was obtained in the same manner as in Example 1, except that the rate of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor was 0.0408 mmol / min, the rate of n-butyllithium as a polymerization initiator was 0.442 mmol / min, the rate of 2,2-bis(2-tetrahydrofuryl)propane added to the second reactor was 0.776 mmol / min, and the rates of coupling agent A and coupling agent B added in the modification step were changed to 0.018 mmol / min and 0.168 mmol / min, respectively.

[0521] (Example 11)

[0522] A modified conjugated diene polymer of Example 11 was obtained in the same manner as in Example 1, except that the rate of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor was 0.0271 mmol / min, the rate of n-butyllithium as a polymerization initiator was 0.297 mmol / min, the rate of 2,2-bis(2-tetrahydrofuryl)propane added to the second reactor was 0.461 mmol / min, and the rates of coupling agent A and coupling agent B added in the modification step were changed to 0.0125 mmol / min and 0.117 mmol / min, respectively.

[0523] (Example 12)

[0524] A modified conjugated diene polymer of Example 12 was obtained in the same manner as in Example 1, except that the rate of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor was 0.0190 mmol / min, the rate of n-butyllithium as a polymerization initiator was 0.187 mmol / min, the rate of 2,2-bis(2-tetrahydrofuryl)propane added to the second reactor was 0.362 mmol / min, and the rates of coupling agent A and coupling agent B added in the modification step were changed to 0.0084 mmol / min and 0.0783 mmol / min, respectively.

[0525] (Example 13)

[0526] A modified conjugated diene polymer of Example 13 was obtained in the same manner as in Example 1, except that the rate of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor was 0.0084 mmol / min, the rate of n-butyllithium as a polymerization initiator was 0.065 mmol / min, the rate of 2,2-bis(2-tetrahydrofuryl)propane added to the second reactor was changed to 0.168 mmol / min, the rate of coupling agent A added in the modification step was changed to 0.0130 mmol / min, no coupling agent B was added, and the amount of SRAE oil added was changed to 25 g per 100 g of the polymer.

[0527] (Example 14)

[0528] A modified conjugated diene polymer of Example 14 was obtained in the same manner as in Example 1 except that the coupling agent A added in the modification step was changed to 0.0067 mmol / min and the coupling agent B was changed to 0.0627 mmol / min.

[0529] (Example 15)

[0530] A modified conjugated diene polymer of Example 15 was obtained in the same manner as in Example 1 except that the coupling agent added in the modification step was changed to 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (coupling agent C) at 0.0895 mmol / min instead of coupling agent A and coupling agent B.

[0531] (Example 16)

[0532] The conjugated diene polymer of Example 16 was obtained in the same manner as in Example 1, except that the rate of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor was 0.0200 mmol / min, the rate of n-butyllithium as a polymerization initiator was 0.198 mmol / min, the rate of 2,2-bis(2-tetrahydrofuryl)propane added to the second reactor was changed to 0.379 mmol / min, and the rates of coupling agent A and coupling agent B added in the modification step were both changed to 0.

[0533] (Example 17)

[0534] The conjugated diene polymer of Example 17 was obtained in the same manner as in Example 1, except that the rate of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor was 0.013 mmol / min, the rate of n-butyllithium as a polymerization initiator was 0.12 mmol / min, the rate of 2,2-bis(2-tetrahydrofuryl)propane added to the second reactor was 0.253 mmol / min, and the rates of coupling agent A and coupling agent B added in the modification step were changed to 0.0059 mmol / min and 0.0546 mmol / min, respectively.

[0535] (Example 18)

[0536] A conjugated diene polymer of Example 18 was obtained in the same manner as in Example 1, except that the rate of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor was 0.012 mmol / min, the rate of n-butyllithium as a polymerization initiator was 0.213 mmol / min, the rate of 2,2-bis(2-tetrahydrofuryl)propane added to the second reactor was changed to 0.405 mmol / min, the rate of coupling agent A added in the modification step was changed to 0.0312 mmol / min, no coupling agent B was added, and the amount of SRAE oil added was changed to 25 g per 100 g of the polymer.

[0537] (Example 19)

[0538] The modified conjugated diene polymer of Example 19 was obtained in the same manner as in Example 1, except that the rates of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor were 0.0209 mmol / min, n-butyllithium as a polymerization initiator was 0.208 mmol / min, n-butyllithium for residual impurity inertization treatment was 0.114 mmol / min, 1,3-butadiene was 21.6 g / min, styrene was 4.57 g / min, and n-hexane was 153 g / min; the rates of 2,2-bis(2-tetrahydrofuryl)propane added to the second reactor were changed to 0.396 mmol / min, n-hexane was changed to 35.5 g / min, and 1,3-butadiene was changed to 7.16 g / min; and the rates of coupling agent A added in the modification step were changed to 0.00917 mmol / min and 0.0856 mmol / min, respectively.

[0539] (Refer to Example 1)

[0540] A modified conjugated diene polymer of Reference Example 1 was obtained in the same manner as in Example 1, except that the rate of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor was 0.136 mmol / min, no 2,2-bis(2-tetrahydrofuryl)propane was added to the second reactor, and the temperatures of the first and second reactors were set at 68° C. and 73° C., respectively.

[0541] (Comparative Example 1)

[0542] A modified conjugated diene polymer of Comparative Example 1 was obtained in the same manner as in Example 1 except that the 1,3-butadiene and styrene supplied to the first reactor were 16.8 g / min and 9.33 g / min, and the 1,3-butadiene added to the second reactor was changed to 7.20 g / min.

[0543] (Comparative Example 2)

[0544] A modified conjugated diene polymer of Comparative Example 2 was obtained in the same manner as in Example 1 except that the 1,3-butadiene supplied to the first reactor was 23.3 g / min and the styrene was 1.00 g / min, and the 1,3-butadiene added to the second reactor was changed to 9.70 g / min.

[0545] (Comparative Example 3)

[0546] A modified conjugated diene polymer of Comparative Example 3 was obtained in the same manner as in Example 1, except that the supply rate of 2,2-bis(2-tetrahydrofuryl)propane to the first reactor was 0.168 mmol / min, and the supply rate of n-butyllithium as a polymerization initiator was 0.297 mmol / min; no 2,2-bis(2-tetrahydrofuryl)propane was added to the second reactor; and the coupling agent A and coupling agent B added in the modification step were changed to 0.0125 mmol / min and 0.117 mmol / min, respectively.

[0547] (Comparative Example 4)

[0548] A modified conjugated diene polymer of Comparative Example 4 was obtained in the same manner as in Example 1, except that the supply rate of 2,2-bis(2-tetrahydrofuryl)propane to the first reactor was 0.106 mmol / min, and the supply rate of n-butyllithium as a polymerization initiator was 0.187 mmol / min; no 2,2-bis(2-tetrahydrofuryl)propane was added to the second reactor; and the coupling agent A and coupling agent B added in the modification step were changed to 0.0084 mmol / min and 0.0783 mmol / min, respectively.

[0549] (Comparative Example 5)

[0550] A conjugated diene polymer of Comparative Example 5 was obtained in the same manner as in Example 1, except that the rate of 2,2-bis(2-tetrahydrofuryl)propane supplied to the first reactor was 0.115 mmol / min, the rate of n-butyllithium as a polymerization initiator was 0.198 mmol / min, no 2,2-bis(2-tetrahydrofuryl)propane was added to the second reactor, the temperatures of the first and second reactors were set at 68° C. and 73° C., respectively, and the amounts of coupling agent A and coupling agent B added in the modification step were both changed to zero.

[0551] (Comparative Example 6)

[0552] A conjugated diene polymer of Comparative Example 6 was obtained in the same manner as in Example 1, except that the supply rate of 2,2-bis(2-tetrahydrofuryl)propane to the first reactor was 0.145 mmol / min, the supply rate of n-butyllithium as a polymerization initiator was 0.239 mmol / min, the addition amount of 1,3-butadiene was 21.0 g / min, the supply rate of styrene was 2.01 g / min, and the supply rate of hexane to the second reactor was changed to 8.99 g / min, the supply rate of styrene was changed to 2.01 g / min, and the supply rate of n-hexane was changed to 32.9 g / min; and no 2,2-bis(2-tetrahydrofuryl)propane was added to the second reactor.

[0553] (Comparative Example 7)

[0554] Four tank-type pressure vessels equipped with a stirrer and a jacket for temperature control were connected as polymerization reactors. The tank-type pressure vessel had an internal volume of 10 L, a ratio (L / D) of internal height (L) to diameter (D) of 4.0, an inlet at the bottom, and an outlet at the top.

[0555] The polymerization step (P1) for synthesizing the first polymer segment is carried out using the first to third polymerization reactors. 1,3-butadiene, which has been previously dehydrated, is mixed at 21.3 g / min, styrene at 6.70 g / min, and n-hexane at 205 g / min. In a static mixer provided in the middle of the piping supplying the mixed solution to the inlet of the reactor, n-butyl lithium for inert treatment of residual impurities is added at 0.104 mmol / min and mixed, and then continuously supplied to the bottom of the reactor. 2,2-bis(2-tetrahydrofuryl)propane as a polar substance is further supplied at a rate of 0.120 mmol / min, and n-butyl lithium as a polymerization initiator is supplied at a rate of 0.205 mmol / min to the bottom of the first reactor that is vigorously mixed using a stirrer, and the temperature in the three reactors is maintained at 45-55°C. After the polymerization reaction reached stability, the total amount of the conjugated diene polymer was discharged from the top of the reactor, an antioxidant (BHT) was added at 0.2 g per 100 g of the conjugated diene polymer, and the solvent was removed. The amount of bonded aromatic vinyl monomer units (X1) in the first polymer segment, the amount of vinyl bonds in the bonded conjugated diene (Y1), and the solid content concentration (m1) were then measured.

[0556] Next, a step (P2) of forming a second polymer segment is carried out using the fourth polymerization reactor.

[0557] The conjugated diene polymer solution was continuously supplied from the top of the first reactor to the bottom of the second reactor. 1,3-Butadiene was added at a rate of 5.30 g / min, n-hexane was added at a rate of 36.0 g / min, and 2,2-bis(2-tetrahydrofuryl)propane as a polar substance was added at a rate of 2.230 mmol / min to the second reactor, and the reaction was continued at 60°C while stirring.

[0558] A conjugated diene polymer of Comparative Example 7 was obtained in the same manner as in Example 1 except that "coupling agent B" was added at a rate of 0.1200 mmol / min after the modification step.

[0559]

[0560]

[0561]

[0562] [Examples 20 to 38], [Reference Example 2], [Comparative Examples 8 to 14]

[0563] Samples 1 to 27 shown in Tables 1 to 3 above were used as raw material rubbers, and rubber compositions containing the respective raw material rubbers were obtained in the following blending ratios.

[0564] Conjugated diene polymer (samples 1 to 27): 100 parts by mass (oil-free)

[0565] Silicon oxide (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa, nitrogen adsorption specific surface area 170 m 2 / g): 85.0 parts by mass

[0566] carbon black

[0567] (Trade name "SEAST 7HM (N234)" manufactured by Tokai Tanso Co., Ltd.): 2.0 parts by mass

[0568] Silane coupling agent (trade name "Si69" manufactured by Evonik Degussa, bis(triethoxysilylpropyl)tetrasulfide): 6.8 parts by mass

[0569] S-RAE oil

[0570] (Trade name "Process NC140" manufactured by JX Nippon Mining and Petrochemical Corporation): 40 parts by mass

[0571] Zinc white: 2.4 parts by mass

[0572] Stearic acid: 1.25 parts by mass

[0573] Anti-aging agent (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 3.5 parts by mass

[0574] Sulfur: 1.0 parts by mass

[0575] Vulcanization accelerator 1

[0576] Tetrabenzylthiuram disulfide: 0.5 parts by mass

[0577] Vulcanization accelerator 2

[0578] N-(tert-butyl)-2-benzothiazolesulfenamide: 2.5 parts by mass

[0579] Total: 246.95 parts by mass

[0580] The above materials were kneaded by the following method to obtain a rubber composition.

[0581] In the first stage of mixing, a closed mixer (0.3 L internal capacity) equipped with a temperature control device was used to mix the raw rubber (Samples 1 to 26), fillers (silica, carbon black), silane coupling agent, process oil, zinc white, and stearic acid at a filling rate of 65% and a rotor speed of 30 to 50 rpm. The closed mixer temperature was controlled to achieve a discharge temperature of 145 to 150°C to obtain the respective rubber compositions (compounds).

[0582] Next, in the second stage of kneading, the mixture obtained above was cooled to room temperature, an antioxidant was added, and kneading was performed again to improve the dispersion of silicon oxide. In this case, the discharge temperature of the mixture was also adjusted to 120°C by temperature control of the mixer.

[0583] After cooling, as the third stage of kneading, sulfur and vulcanization accelerators 1 and 2 were added and kneaded in an open roll mill set at 70°C.

[0584] Thereafter, the molded product was vulcanized at 160° C. for 20 minutes using a vulcanizing press.

[0585] Evaluation was performed on the rubber composition before vulcanization and the rubber composition after vulcanization.

[0586] Specifically, the evaluation was performed by the following method.

[0587] [Evaluation 1, Evaluation 2: Viscoelastic parameters]

[0588] Viscoelastic parameters were measured in a torsional vibration mode using a viscoelasticity tester "ARES" manufactured by Rheometric Scientific.

[0589] The result for the rubber composition of Reference Example 2 was set to 100, and each measured value was indexed.

[0590] (Evaluation 1)

[0591] Tan δ measured at 0°C, 10 Hz frequency, and 1% strain is used as an index of wet grip performance. A larger index indicates better wet grip performance.

[0592] When the index value is 80 or more, it is judged that the sulfide has sufficient wet grip performance.

[0593] (Evaluation 2)

[0594] The storage modulus G' measured under the conditions of -20°C, a frequency of 10 Hz, and a strain of 1% was used as an indicator of low-temperature properties.

[0595] A larger index indicates better winter characteristics.

[0596] In addition, when the index value is 50 or more, it is judged that the sulfide has sufficient winter performance.

[0597] [Evaluation 3: Wear resistance]

[0598] The wear amount was measured at a load of 44.4 N and 1000 revolutions using an Akron abrasion tester (manufactured by Yasuda Seiki Co., Ltd.) in accordance with JIS K6264-2, and the result of Reference Example 2 was set as 100 and indexed.

[0599] A larger index indicates better wear resistance.

[0600] [Evaluation 4: Processability]

[0601] The unvulcanized modified conjugated diene polymers or conjugated diene polymers produced by the methods described in the Examples, Reference Examples, and Comparative Examples were visually observed for aggregation (shape) immediately after discharge from the pressurized kneader (immediately after completion of kneading with the pressurized kneader in the first kneading stage) and evaluated by each evaluator based on the following criteria, with 5 points being the full score.

[0602] Aggregation is an indicator of the workability of sulfides.

[0603] A larger index indicates better workability.

[0604] <Evaluation Criteria>

[0605] 1: Less than 50% of the end portion of the sheet is smooth, and workability is very poor

[0606] 2: More than 50% and 60% or less of the sheet end portion is smooth, and workability is poor.

[0607] 3: More than 60% and 80% or less of the sheet end portion is smooth, and the workability is good.

[0608] 4: More than 80% and 90% or less of the sheet end portion is smooth, and the workability is excellent.

[0609] 5: More than 90% of the end portion of the sheet is smooth, and the workability is very excellent.

[0610] [Evaluation 5: Tensile Properties]

[0611] The tensile strength and elongation at break were measured according to the tensile test method of JIS K6251, and the product of the results of Reference Example 2 was indexed, with the result of Reference Example 2 being 100.

[0612] A larger index indicates better tensile strength and elongation at break (breaking strength).

[0613] When the index value is 80 or more, it is judged that the vulcanizate has sufficient tensile properties.

[0614]

[0615] As shown in Tables 4 to 6, the rubber compositions of Examples 20 to 38 using Samples 1 to 19, in which the difference in the amount of bound styrene, the difference in the amount of vinyl bonds, and the estimated glass transition temperature all fell within the preferred ranges, were confirmed to exhibit an excellent balance between wet grip performance and winter performance when vulcanized, as compared to the rubber compositions of Reference Example 2 and Comparative Examples 8 to 14 using Samples 20 to 27. The rubber compositions also exhibited sufficient wear resistance and tensile properties.

[0616] In addition, when Example 30 and Comparative Example 10, and Example 31 and Comparative Example 11, respectively, using modified conjugated diene polymers having similar molecular weights and estimated glass transition temperatures, it was confirmed that the examples had an excellent balance between wet grip performance and winter performance, and had sufficient wear resistance and tensile properties.

[0617] Furthermore, when Example 35 and Comparative Example 12 were compared, even when unmodified conjugated diene polymers were used, the Example was confirmed to have a good balance between wet grip performance and winter performance, and to have excellent wear resistance and tensile properties.

[0618] This application is based on Japanese patent application No. 2023-072878 filed with the Japan Patent Office on April 27, 2023, the contents of which are incorporated into this specification by reference.

[0619] Industrial Applicability

[0620] The conjugated diene polymer of the present invention has industrial applicability as a material for tire treads, automobile interior and exterior parts, anti-vibration rubber, conveyor belts, footwear, foams, and various industrial products.

Claims

1. A conjugated diene polymer having two or more polymer segments, wherein: The absolute value of the difference between the amount X1 of the bonded aromatic vinyl monomer unit in the first polymer segment and the amount X2 of the bonded aromatic vinyl monomer unit in the second polymer segment, i.e., |X1-X2|, is 5% by mass or less, where the units of X1 and X2 are mass %. The difference between the vinyl bond amount Y1 in the conjugated diene of the first polymer segment and the vinyl bond amount Y2 in the conjugated diene of the second polymer segment, i.e., Y2-Y1, is 15 mol% or more and 50 mol% or less, and the units of Y1 and Y2 are mol%, The estimated glass transition temperature, ie, estimated Tg, of the conjugated diene polymer is from -72°C to -40°C.

2. The conjugated diene polymer according to claim 1, wherein The ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 1.7 or more.

3. The conjugated diene polymer according to claim 1, wherein The ratio of the mass ratio r1 of the first polymer segment to the mass ratio r2 of the second polymer segment, ie, R=r1 / r2, is 0.25-4.

4. The conjugated diene polymer according to claim 1, wherein The weight average molecular weight Mw is 350,000 to 1,350,000. 5 . The conjugated diene polymer according to claim 1 , which has a nitrogen-containing modified group and a modification rate of 60% or more.

6. A method for producing a conjugated diene polymer, which is the method for producing a conjugated diene polymer according to claim 1, comprising the following steps: A polymerization step P1, forming the first polymer segment using two or more continuous reactors; and Polymerization step P2, forming the second polymer segment at the end of the first polymer segment obtained in P1, In the polymerization step P2, a polar substance is additionally added.

7. The method for producing a conjugated diene polymer according to claim 6, wherein: In the polymerization step P2, a conjugated diene compound is additionally added. 8 . The method for producing a conjugated diene polymer according to claim 6 , further comprising a coupling step of reacting the conjugated diene polymer with a coupling agent having a nitrogen atom-containing group after the polymerization step P2 .

9. The method for producing a conjugated diene polymer according to claim 7, wherein: The amount of the conjugated diene compound added in the polymerization step P2 is 15% by mass or more of the total amount of the conjugated diene compound added.

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