Modified conjugated diene polymer and method for producing modified conjugated diene polymer

Abstract

The modified conjugated diene polymer includes a conjugated diene monomer unit and an aromatic vinyl monomer unit, has a weight average molecular weight measured by GPC of 700,000 or more, has a modification rate of 60% or more, has one tanδ peak in a temperature range of -100°C to 100°C in a tanδ peak graph corresponding to temperatures derived from dynamic viscoelasticity analysis based on <Condition 1> by an ARES (Advanced Rheometric Expansion System), and has a height of the tanδ peak of from 0.90 to 1.45. <Condition 1> A tanδ peak graph is obtained by using a dynamic mechanical analyzer in torsional mode under conditions of a frequency of 10 Hz, a deformation rate (Strain) of 0.5%, and a temperature elevation rate of 5° C / min.

Description

Modified conjugated diene polymer and method for producing modified conjugated diene polymer

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

[0002] The basic functions required for automobile tires include wet grip performance and tensile performance, and in recent years, fuel efficiency and wear resistance have also been required from the perspective of reducing environmental impact.

[0003] As a rubber material for tires that meets the demands for improving various properties as described above, for example, a rubber composition containing a conjugated diene rubbery polymer and a reinforcing filler such as carbon black and silica has been known. In such rubber compositions, attempts have been made to improve the dispersibility of the filler in the rubber composition and to improve various properties such as abrasion resistance by introducing a functional group having affinity or reactivity with the filler into the molecular terminal of the highly mobile conjugated diene polymer.

[0004] However, wet grip performance, which is a characteristic generally required of tire tread rubber in terms of braking performance on wet road surfaces, is a contradictory characteristic to abrasion resistance. In other words, improving one of these characteristics tends to cause a deterioration of the other. Therefore, tire tread rubber is required to resolve this contradiction in properties.

[0005] Furthermore, in order to improve the abrasion resistance of a rubber composition, there have been many attempts to increase the content of cis-trans bonded conjugated diene polymers in the conjugated diene polymers used in the rubber composition. However, rubber compositions containing a large amount of such cis-trans bonded conjugated diene polymers have the problem of very poor processability.

[0006] On the other hand, from the viewpoint of tire durability, rubber compositions are also required to have excellent tensile properties. As described above, when a plurality of rubber materials are used to resolve the trade-off between wet grip performance and abrasion resistance and improve both properties, if the mutual affinity of these plurality of rubber materials is low, the mechanical strength of the rubber composition tends to decrease. Therefore, a rubber composition that resolves the trade-off between wet grip performance and abrasion resistance and has excellent mechanical strength is required.

[0007] For example, Patent Documents 1 to 3 disclose rubber compositions containing silica and a modified conjugated diene polymer obtained by reacting an amino group-containing alkoxysilane with the active terminal of a conjugated diene polymer. Patent Document 4 discloses a rubber composition containing a modified conjugated diene polymer with a low vinyl bond content. Patent Document 5 discloses a rubber composition containing a conjugated diene polymer composition blended with multiple types of modified conjugated diene polymers.

[0008] Japanese Patent Application Laid-Open No. 2005-290355 Japanese Patent Application Laid-Open No. 11-189616 Japanese Patent Application Laid-Open No. 2003-171418 Japanese Patent No. 6512240 Japanese Patent Application Laid-Open No. 2021-143324

[0009] However, conventionally known rubber compositions, including those disclosed in Patent Documents 1 to 4, still have the problem that there is room for improvement in their physical properties. For example, with a rubber composition containing a conventional conjugated diene polymer, attempts to improve wet grip performance result in decreased winter performance and worsened performance on snowy and icy roads, making it difficult to achieve both. Furthermore, when such a rubber composition is vulcanized, particularly when it is vulcanized to contain an inorganic filler such as silica, the dispersibility of the silica decreases, resulting in poor flexibility and poor performance on snowy and icy roads, as well as insufficient abrasion resistance.

[0010] Furthermore, upon detailed investigation of the rubber composition described in Patent Document 5, it was found that the composition is suitable for tire design that places emphasis on fuel-saving performance, but on the other hand, as a material for general summer tires, there is still room for improvement in terms of wet grip performance and abrasion resistance.

[0011] Therefore, an object of the present invention is to provide a modified conjugated diene polymer that can provide a rubber composition that combines excellent wet grip performance and abrasion resistance and is also excellent in fuel economy and tensile properties, and a method for producing the modified conjugated diene polymer.

[0012] As a result of intensive investigations conducted by the present inventors to solve the above problems, it was found that a modified conjugated diene polymer can be provided that has a predetermined weight average molecular weight and modification rate, and that, when shown in a tan δ peak graph as a function of temperature derived from dynamic viscoelasticity analysis, has one peak in a predetermined temperature range, and that the tan δ peak height is set within a predetermined range, from which a rubber composition can be obtained that achieves both wet grip performance and abrasion resistance and is also excellent in fuel economy and tensile properties.

[0013] [1] A modified conjugated diene polymer containing conjugated diene monomer units and aromatic vinyl monomer units, having a weight-average molecular weight of 700,000 or more as measured by GPC, a modification rate of 60% or more, and having one tan δ peak in the temperature range of -100°C to 100°C in a tan δ peak graph as a function of temperature derived from dynamic viscoelasticity analysis using an ARES (Advanced Rheometric Expansion System) based on the following <Condition 1>, wherein the height of the tan δ peak is 0.90 or more and 1.45 or less. <Condition 1> Measurement is performed using a dynamic mechanical analyzer in torsion mode under conditions of a frequency of 10 Hz, a deformation rate (Strain) of 0.5%, and a heating rate of 5°C / min to obtain the tan δ peak graph. [2] The modified conjugated diene polymer according to [1] above, having a branching degree (Bn) of 7 or more as measured by a GPC-light scattering method with a viscosity detector. [3] The modified conjugated diene polymer according to [1] or [2] above, having a molecular weight distribution of 1.7 or more and 2.5 or less. [4] The modified conjugated diene polymer according to any one of [1] to [3] above, having an estimated glass transition temperature (estimated Tg) derived from the microstructure in the modified conjugated diene polymer of -62°C or more and less than -25°C. [5] The modified conjugated diene polymer according to any one of [1] to [4] above, having two or more polymer segments, the mass fraction of which in the modified conjugated diene polymer is 10% or more, the first polymer segment which is the polymer segment closest to the initiation terminal has an estimated glass transition temperature (estimated Tg) of -90°C or more and -40°C or less, the second polymer segment which is the polymer segment closest to the termination terminal has an estimated Tg of -50°C or more and -10°C or less and is equal to or higher than the estimated Tg of the first polymer segment, and a modifier is bonded to an end of the second polymer segment. [6] The modified conjugated diene polymer according to any one of [1] to [5] above, having a modifier residue derived from an alkoxysilane compound having a nitrogen atom.[7] The method for producing a conjugated diene polymer according to any one of [1] to [6] above, comprising: a polymerization step of polymerizing at least one conjugated diene compound using a lithium compound as a polymerization initiator in a continuous reactor having two or more reactors connected in series, wherein the continuous reactor has a monomer addition section for adding at least one conjugated diene compound and an aromatic vinyl compound during the polymerization step; and a coupling step of reacting the conjugated diene polymer obtained in the polymerization step with a nitrogen atom-containing modifier. [8] The method for producing a modified conjugated diene polymer according to [7] above, wherein an aromatic vinyl compound is used as a polymerization monomer in the polymerization step, and the conversion rate of the aromatic vinyl compound in the polymerization intermediate in the monomer addition section is 70% or more. [9] The method for producing a modified conjugated diene polymer according to [7] above or [8] above, wherein the monomer addition section is located between the pipes of the first and second continuous reactors.

[10] The method for producing a modified conjugated diene polymer according to any one of [7] to [9], wherein a branching agent is added in the monomer additional addition section.

[0014] According to the present invention, it is possible to provide a modified conjugated diene polymer from which a rubber composition can be obtained which has both excellent wet grip performance and abrasion resistance, and is also excellent in fuel economy and tensile properties.

[0015] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0016] [Modified Conjugated Diene Polymer] The modified conjugated diene polymer of the present embodiment contains conjugated diene monomer units and aromatic vinyl monomer units.

[0017] The modified conjugated diene polymer of this embodiment has a weight-average molecular weight of 700,000 or more as measured by GPC (gel permeation chromatography), a modification rate of 60% or more, and in a tan δ peak graph as a function of temperature derived from dynamic viscoelasticity analysis using an ARES (Advanced Rheometric Expansion System) based on the following <Condition 1>, the polymer has one tan δ peak in the temperature range of -100°C to 100°C, and the height of the tan δ peak is 0.90 or more and 1.45 or less. <Condition 1> Measurement is performed using a dynamic mechanical analyzer in torsion mode under conditions of a frequency of 10 Hz, a deformation rate (Strain) of 0.5%, and a heating rate of 5°C / min to obtain a tan δ peak graph.

[0018] According to the above-mentioned configuration, the modified conjugated diene polymer can provide a rubber composition that has both excellent wet grip performance and abrasion resistance, and is also excellent in fuel economy and tensile properties.

[0019] (Conjugated Diene Compound) The modified conjugated diene polymer of this embodiment contains a conjugated diene monomer unit. Examples of conjugated diene compounds that form the conjugated diene monomer units 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, from the viewpoint of ease of industrial availability, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. These compounds may be used alone or in combination of two or more.

[0020] (Aromatic Vinyl Compound) The modified conjugated diene polymer of this embodiment contains an aromatic vinyl monomer unit. Examples of aromatic vinyl compounds that form the aromatic vinyl monomer unit include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, from the viewpoint of ease of industrial availability, styrene or p-methylstyrene is preferred, and styrene is more preferred. These compounds may be used alone or in combination of two or more.

[0021] (Amount X of Bound Aromatic Vinyl Monomer Units) In this specification, the amount X (% by mass) of bound aromatic vinyl monomer units is the value of the mass fraction (% by mass) of bound aromatic vinyl monomer units relative to the total mass of the modified conjugated diene-based polymer or the polymer segment described below.

[0022] Here, the amount of bound aromatic vinyl monomer units can be calculated by measuring the ultraviolet absorption of the phenyl group in the portion of the modified conjugated diene polymer derived from the aromatic vinyl compound (hereinafter referred to as "bound aromatic vinyl monomer units"). Furthermore, the amount of bound conjugated diene monomer units can also be determined from the amount of bound aromatic vinyl monomer obtained as described above. Specifically, it can be measured by the method described in the Examples below.

[0023] (Amount of vinyl bonds Y in bound conjugated diene) In this specification, the amount of vinyl bonds Y (mol %) in the bound conjugated diene is the molar fraction (mol %) of 1,2-bond units relative to the polymerization units derived from the conjugated diene contained in the modified conjugated diene-based polymer or the polymer segment described below.

[0024] When the modified conjugated diene polymer of the present embodiment is a polymer of butadiene and styrene, the vinyl bond amount in the bound conjugated diene can be obtained by determining the vinyl bond amount (1,2-bond amount) in the bound butadiene by the Hampton method (R.R. Hampton, Analytical Chemistry, 21, 923 (1949)). Specifically, it can be measured by the method described in the examples below.

[0025] (Microstructure) In this specification, the microstructure refers to the composition of the polymer, including the distinction between isomers, in the modified conjugated diene polymer or the polymer segment described below. In the modified conjugated diene polymer of this embodiment, the mass of the copolymer consisting of styrene and butadiene is preferably 70 mass% or more, more preferably 80 mass% or more, and even more preferably 90 mass% or more, based on the mass of the entire modified conjugated diene polymer.

[0026] (Content of Bound Aromatic Vinyl Monomer Unit Block) The modified conjugated diene polymer of this embodiment preferably has a small number of blocks in which four or more bound aromatic vinyl monomer units are linked (hereinafter, may be referred to as bound aromatic vinyl monomer unit blocks), or has no bound aromatic vinyl monomer unit blocks. The small number or absence of bound aromatic vinyl monomer unit blocks makes the modified conjugated diene polymer of this embodiment less likely to have two or more glass transition temperatures (Tg). When the modified conjugated diene polymer is a butadiene-styrene copolymer, the content of bound aromatic vinyl monomer unit blocks in the modified conjugated diene polymer can be measured by a known method in which the modified conjugated diene polymer is decomposed by the Kolthoff method (the method described in I. M. KOLTHOFF, et al., J. Polym. Sci. 1, 429 (1946)) and the amount of polystyrene insoluble in methanol is analyzed. The content of the bound aromatic vinyl monomer unit block measured by such a method is preferably 1.0 mass% or less, more preferably 0.1 mass% or less, and even more preferably 0 mass% relative to the total amount of the modified conjugated diene polymer. By not including a bound aromatic vinyl monomer unit block in the modified conjugated diene copolymer or in the polymer segment described below, the modified conjugated diene polymer tends to exhibit continuous properties with temperature change. As a result, vulcanizates using the modified conjugated diene polymer tend to exhibit continuous changes over a wide temperature range and have excellent tensile strength.

[0027] (Method for Estimating Glass Transition Temperature of Polymer): Estimated Glass Transition Temperature (Estimated Tg) The glass transition temperature of the modified conjugated diene polymer of this embodiment can be estimated using the Gordon-Taylor equation (Gordon, M.; Taylor, J.S.J. Appl. Chem. 1952, 2, 493.) expanded to a system of two or more components of the following formula (1). This value is referred to as the estimated glass transition temperature.

[0028]

[0029] In the formula (1), the variable subscript i represents each component of the microstructure contained in the modified conjugated diene polymer, and 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 component i in the modified conjugated diene polymer, 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 actual measurements can be used. For example, when a modified conjugated diene polymer contains styrene, if one of the i's is a styrene component, Δα is calculated from 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 x 10 －４ K －１ , Tg from the measured value of the glass transition temperature i = 105.3°C, and from the measured density value, ρ i = 1.02 g / cm ３ can be used.

[0030] For example, when the modified conjugated diene polymer is a butadiene-styrene random copolymer, the amount of bound aromatic vinyl monomer units X ａｌｌ (mass%), and the vinyl bond amount Y in the bound conjugated diene ａｌｌ (mol%), and the thermal expansion coefficients (Δa i ), glass transition temperature (Tg i ), density (ρ i ) the estimated glass transition temperature (estimated Tg) can be calculated from the following formula (i).

[0031]

[0032] The amount of bound aromatic vinyl monomer units X relative to the denominator of the formula (i) ａｌｌ (mass%), vinyl bond amount Y in the bonded conjugated diene ａｌｌSince the influence of the product value of (mol%) is very small, it can be approximated by the following formula (ii): Furthermore, the following formula (ii) can be approximated as the following formula (iii):

[0033]

[0034]

[0035] That is, when the modified conjugated diene polymer of the present embodiment is a butadiene homopolymer or a butadiene-styrene random copolymer, the glass transition temperature (estimated Tg) of the modified conjugated diene polymer can be estimated by the above formula (iii) from values ​​usually used in design.

[0036] As described above, the amount of bound aromatic vinyl monomer units X in the modified conjugated diene polymer of this embodiment ａｌｌ (mass%), vinyl bond amount Y in the bonded conjugated diene ａｌｌ The mass proportion of each microstructure component can be determined from the microstructure such as (mol%), and the glass transition temperature (estimated Tg) of the modified conjugated diene polymer can be calculated from the formula (1). That is, the formula (1) is expressed by the amount of bound aromatic vinyl monomer units X ａｌｌ (mass%), vinyl bond amount Y in the bonded conjugated diene ａｌｌ It is a measure of the change in the glass transition temperature of a modified conjugated diene polymer relative to the change in the molecular weight (mol%).

[0037] When the value of the formula (1) is small, the glass transition temperature (Tg) of the modified conjugated diene polymer of this embodiment is small, and when the value is large, the glass transition temperature (Tg) is high. For example, when the formula (1) is −60° C., the glass transition temperature of the modified conjugated diene polymer is estimated to be −60° C., and when the formula (1) is −40° C., the glass transition temperature is estimated to be −40° C.

[0038] As described above, the value of formula (1) calculated from the polymer microstructure is generally an index of the glass transition temperature of a modified conjugated diene polymer. However, the present inventors have found that when the relaxation temperature of a modified conjugated diene polymer near the measured glass transition temperature is wide, the viscoelasticity of the actual vulcanizate does not necessarily agree with the viscoelasticity calculated from the estimated value of the glass transition temperature (estimated Tg) according to formula (1) calculated from the microstructure. Specifically, when the absolute value of the difference in estimated glass transition temperature between polymer segments (described below) is 33°C or more, or the absolute value of the difference in the amount of bound aromatic vinyl monomer units between polymer segments (described below) is 25% by mass or more, the discrepancy between the glass transition temperature estimated from formula (1) and the measured glass transition temperature tends to become significant. Therefore, from the perspective of controlling the performance of a vulcanizate affected by the glass transition temperature, they have found that adjusting the estimated glass transition temperature (estimated Tg) according to formula (1) calculated from the microstructure is more effective than adjusting the measured glass transition temperature of the modified conjugated diene polymer to a specific value. This is thought to be because DSC (differential scanning calorimetry) picks up small energy changes, so that the entire glass transition temperature is pulled at the start of relaxation in the low Tg portion of the modified conjugated diene polymer, resulting in the actually measured glass transition temperature being lower than the estimated glass transition temperature. For example, it has been experimentally confirmed that even if the entire microstructure of a modified conjugated diene polymer is the same, the glass transition temperature measured by DSC can differ by about 2 to 5°C depending on the difference in the microstructure of each segment.

[0039] The lower limit of the estimated Tg derived from the microstructure of the modified conjugated diene polymer of this embodiment is preferably −62°C or higher, more preferably −58°C or higher, and even more preferably −55°C or higher. When the lower limit of the estimated Tg is within the above range, the wet grip performance and tensile properties of the vulcanizate of the modified conjugated diene polymer of this embodiment tend to be improved. Furthermore, the upper limit of the estimated Tg derived from the microstructure of the modified conjugated diene polymer of this embodiment is preferably less than −25°C, more preferably −35°C or lower, and even more preferably −40°C or lower. When the upper limit of formula (1) is within the above range, the abrasion resistance and fuel economy performance of the vulcanizate of the modified conjugated diene polymer of this embodiment tend to be improved. Formula (1) can be controlled to the above-mentioned numerical range by adjusting the microstructure of the modified conjugated diene polymer. For example, in the case of a butadiene-styrene copolymer, the bound styrene amount X of the modified conjugated diene polymer can be calculated by the above formula (iii). ａｌｌ (mass%), vinyl bond amount Y in butadiene ａｌｌ By adjusting the (mol %), it is possible to control the content within the above-mentioned range.

[0040] (Polymer Segment) The modified conjugated diene polymer of this embodiment preferably has two or more polymer segments. A polymer segment refers to a portion of a modified conjugated diene polymer composed of conjugated diene monomer units and aromatic vinyl monomer units, or composed of conjugated diene monomer units. A polymer segment is preferably composed of conjugated diene monomer units and aromatic vinyl monomer units. Furthermore, the modified conjugated diene polymer of this embodiment preferably has a small number or no blocks in which four or more linked aromatic vinyl monomer units are chained. The multiple polymer segments contained in the modified conjugated diene polymer of this embodiment have different microstructures. Each polymer segment may differ, for example, in the amount of linked aromatic vinyl monomer units or the amount of vinyl bonds in the linked conjugated diene, and each polymer segment can be distinguished by the method described in the examples below.

[0041] As described above, the modified conjugated diene polymer of the present embodiment preferably has two or more polymer segments. By having two or more polymer segments, one modified conjugated diene polymer undergoes glass transition in multiple temperature ranges.

[0042] The polymer segments are produced by a continuous polymerization method and are characterized by having a molecular weight distribution, unlike the block structure typically produced by batch polymerization. A single modified conjugated diene-based polymer contains multiple polymer segments, each with its own molecular weight distribution, resulting in different glass transition temperatures for each molecule due to the overlap of these distributions. That is, depending on the molecular weight combination of the different polymer segments, each molecule behaves as if it has a different glass transition temperature. For example, when a low-molecular-weight, low-glass transition temperature component is bonded to a high-molecular-weight, high-glass transition temperature component, the molecule behaves as if it were a high-glass transition temperature component, whereas when a high-molecular-weight, low-glass transition temperature component is bonded to a low-molecular-weight, high-glass transition temperature component, the molecule behaves as if it were a low-glass transition temperature component. Therefore, the modified conjugated diene-based polymer of this embodiment has a continuous glass transition temperature distribution.

[0043] The formula (1) can also be applied to polymer segments, and the amount of bound aromatic vinyl monomer units (X １ , X ２ ) and the vinyl bond amount (Y １ , Y ２ ) and calculate the estimated glass transition temperature (estimated Tg １ , estimated Tg ２ ) can be obtained.

[0044] In this specification, of the two or more polymer segments contained in the modified conjugated diene polymer, the polymer segment closest to the initiation terminal and accounting for 10% or more of the mass fraction of the modified conjugated diene polymer are referred to as the "first polymer segment," and the polymer segment closest to the termination terminal is referred to as the "second polymer segment." The boundary between polymer segments is defined as a point where there is an abrupt change in microstructure. In this embodiment, as an example, in the production method described below, the portion polymerized up to the addition of a conjugated diene compound, preferably a conjugated diene compound and an aromatic vinyl compound, is defined as the first polymer segment, and the portion polymerized thereafter is defined as the second polymer segment. The modified conjugated diene polymer of this embodiment may contain polymer segments other than the first polymer segment and the second polymer segment. However, from the viewpoint of ease of production, it is preferably composed of two polymer segments. Furthermore, from the viewpoint of a balance between wet grip performance and abrasion resistance, the ratio of the sum of the masses of the first polymer segment and the second polymer segment to the total mass of the modified conjugated diene polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0045] In the modified conjugated diene polymer of this embodiment, the lower limit of the estimated glass transition temperature (estimated Tg) of the first polymer segment is preferably −90°C or higher, more preferably −75°C or higher, and even more preferably −65°C or higher. When the lower limit of the estimated Tg of the first polymer segment is within the above range, the wet grip performance and tensile properties of the vulcanizate of the modified conjugated diene polymer of this embodiment tend to be improved. Furthermore, the upper limit of the estimated Tg of the first polymer segment is preferably −40°C or lower, more preferably −45°C or lower, and even more preferably −50°C or lower. When the upper limit of the estimated Tg of the first polymer segment is within the above range, the abrasion resistance and fuel economy performance of the vulcanizate of the modified conjugated diene polymer of this embodiment tend to be improved. The estimated Tg can be controlled to the above-mentioned numerical range by adjusting the microstructure of the modified conjugated diene polymer. For example, in the case of a butadiene-styrene polymer, the bound styrene amount X of the first polymer segment can be calculated using the above formula (iii): １(mass%), vinyl bond amount Y in butadiene １ By adjusting the (mol %), it is possible to control the content within the above-mentioned range.

[0046] In the modified conjugated diene polymer of this embodiment, the lower limit of the estimated Tg of the second polymer segment is preferably −50°C or higher, more preferably −45°C or higher, and even more preferably −35°C or higher. When the lower limit of the estimated Tg of the second polymer segment is within the above range, the wet grip performance and tensile properties of the vulcanizate of the modified conjugated diene polymer of this embodiment tend to be improved. Furthermore, the upper limit of the estimated Tg of the second polymer segment is preferably −10°C or lower, more preferably −15°C or lower, and even more preferably −20°C or lower. The estimated Tg of the second polymer segment is preferably equal to or higher than the estimated Tg of the first polymer segment. Furthermore, the modifier is preferably bonded to the end of the second polymer segment. When the upper limit of the estimated Tg is within the above range, the abrasion resistance and fuel economy performance of the vulcanizate of the modified conjugated diene polymer of this embodiment can be improved. The estimated Tg can be controlled to the above-mentioned numerical range by adjusting the microstructure of the modified conjugated diene polymer. For example, in the case of a butadiene-styrene polymer, the bound styrene amount X of the second polymer is calculated by the formula (iii): ２ (mass%), vinyl bond amount Y in butadiene ２ By adjusting the (mol %), it is possible to control the content within the above-mentioned range.

[0047] By precisely controlling the ratio of the average molecular weights of the first polymer segment and the second polymer segment and the difference in estimated glass transition temperature between them, it is possible to control the height of the tan δ peak of the modified conjugated diene polymer described below within a predetermined range, and to obtain a modified conjugated diene polymer that can be used to produce a vulcanizate that has an excellent balance between wet grip performance and abrasion resistance while suppressing a decrease in tensile strength.

[0048] The difference between the estimated glass transition temperatures of the first polymer segment and the second polymer segment (|Estimated Tg ２ -Estimated Tg １As the value of | increases, the glass transition occurs more slowly over a wider temperature range, and the height of the tan δ peak of the modified conjugated diene polymer tends to decrease.

[0049] Although polymer segments can be defined in conventionally known continuously polymerized conjugated diene polymers, the change in estimated glass transition temperature is small and the glass transition behavior is sharp in a narrow temperature range. On the other hand, in the modified conjugated diene polymer of the present embodiment, the multiple polymer segments each have a different glass transition temperature, and as described above, the glass transition occurs gradually over a wide temperature range, so that the height of the tan δ peak of the modified conjugated diene polymer tends to decrease significantly, thereby achieving both wet grip performance and abrasion resistance.

[0050] In the modified conjugated diene-based polymer of this embodiment, the lower limit of the difference in estimated glass transition temperature between the first polymer segment and the second polymer segment is preferably 18° C. or more, more preferably 25° C. or more, and even more preferably 30° C. or more. The upper limit of the difference in estimated glass transition temperature between the first polymer segment and the second polymer segment is preferably 60° C. or less, more preferably 50° C. or less, and even more preferably 40° C. or less.

[0051] (Polymer Segment Ratio) As the ratio of the average molecular weights of the first polymer segment and the second polymer segment approaches 1, the glass transition tends to occur more slowly over a wider temperature range, and therefore the height of the tan δ peak, which correlates with the amount of local glass transition in a narrow temperature range, tends to decrease.

[0052] In the modified conjugated diene polymer of this embodiment, the first and second polymer segments preferably have a predetermined mass ratio. The polymer segment mass ratio represents the average mass fraction of each polymer segment relative to the entire modified conjugated diene polymer. The mass ratios of the first and second polymer segments in the modified conjugated diene polymer of this embodiment are defined as the mass ratios of the polymer segments obtained in steps P1 and P2, which are polymerization steps for each polymer segment, to the total mass of the modified conjugated diene polymer. In addition, the first polymer segment mass ratio (r １), and the second polymer segment mass ratio (r ２ ) ratio (R = r １ / r ２ (hereinafter, sometimes referred to as the ratio of the mass ratios of the polymer segments.) 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 more, the fuel-saving performance of the vulcanized product tends to be excellent. Furthermore, when the upper limit of R is 4 or less, the processability of the vulcanized product tends to be excellent. The ratio R of the mass ratios of the polymer segments can be measured by the method described in the examples below, and can be controlled to be within the above numerical range by adjusting conditions such as the polymerization time, polymerization temperature, amount of monomer added, and amount of vinyl bond in the polymerization step of each polymer segment in the production process of the modified conjugated diene-based polymer of this embodiment.

[0053] The method of introducing multiple polymer segments into the molecule of a modified conjugated diene polymer is carried out by using a continuous reactor in which multiple reactors are connected in series, as described below, and sequentially adding a conjugated diene compound, an aromatic vinyl compound, a polar substance, and a solvent to each reactor by continuous solution polymerization. The sequentially added substances may be the same or different between reactors.

[0054] (Tan δ Peak Height) The modified conjugated diene polymer of this embodiment has one tan δ peak in the temperature range of -100°C to 100°C in a tan δ peak graph as a function of temperature derived from dynamic viscoelasticity analysis based on the above <Condition 1> using an ARES (Advanced Rheometric Expansion System), and the height of the tan δ peak is 0.90 to 1.45, preferably 0.90 to 1.25, and more preferably 0.90 to 1.15. When the tan δ peak height is within this range, the modified conjugated diene polymer has a polymer segment with excellent wet grip performance having a high concentration of aromatic vinyl monomer units and a high concentration of vinyl-bonded conjugated diene monomer units, while suppressing a decrease in intramolecular compatibility, and tends to produce a vulcanizate with excellent balance between wet grip performance and abrasion resistance while suppressing a decrease in tensile strength.

[0055] In this specification, the term "tan δ peak" refers to a peak that appears in a tan δ peak graph corresponding to temperature derived from dynamic viscoelastic analysis when a modified conjugated diene-based polymer is measured using a dynamic mechanical analyzer (TA Corporation, ARES-G2) in a torsional mode under conditions of a frequency of 10 Hz, a deformation rate (Strain) of 0.5%, and a heating rate of 5°C / min, and the "height of the tan δ peak" is defined as the value of tan δ at the peak top.

[0056] In general methods for producing random copolymers, polymerization conditions such as polymerization temperature, monomer, and polymerization catalyst concentration are rarely intentionally changed significantly during polymerization from the viewpoints of production stability and cost, and therefore the tan δ peak of such random copolymers is high and sharp. This is often due to the high randomness of the aromatic vinyl monomer units and the uniform microstructure throughout, and such random copolymers exhibit a significant trade-off between wet grip performance and abrasion resistance.

[0057] On the other hand, in the case of block copolymers produced by batch polymerization or the like, the tan δ peak tends to be significantly broadened, the tan δ peak height reduced, or the tan δ peak split into two or more peaks. This is due to the formation of blocks in which aromatic vinyl monomer units are continuous within the conjugated diene polymer, or the aromatic vinyl monomer units being distributed excessively densely on one side of the block copolymer chain, resulting in reduced randomness, which causes phase separation, and the tensile strength tends to be poor when vulcanized.

[0058] The height of the tan δ peak indicates the degree of randomness of the microstructure inside the molecule. When the tan δ peak height is 0.90 or more and 1.45 or less, the modified conjugated diene-based polymer has polymer segments having excellent wet grip performance and having a high concentration of aromatic vinyl monomer units and a high concentration of vinyl-bonded conjugated diene monomer units while suppressing a decrease in intramolecular compatibility, and a modified conjugated diene-based polymer can be obtained that can produce vulcanizates having a balance of excellent wet grip performance and abrasion resistance while suppressing a decrease in tensile strength.

[0059] In order to control the tan δ peak height of the modified conjugated diene polymer of this embodiment to 0.90 or more and 1.45 or less, it is effective to control the microstructure of the two polymer segments. Specifically, the tan δ peak height can be lowered by increasing the difference in estimated Tg between the two polymer segments and bringing the ratio of their average molecular weights closer to 1. Conversely, the tan δ peak height can be increased by increasing the difference in estimated Tg and moving the ratio of their average molecular weights away from 1. One method for controlling the difference in estimated Tg between the two polymer segments is to polymerize the aromatic vinyl monomer units and vinyl-bonded conjugated diene monomer units so that they are appropriately randomly distributed. Specifically, this can be controlled by adding a conjugated diene compound and an aromatic vinyl compound between the polymerization steps of the first and second polymer segments, and adjusting the amounts of aromatic vinyl monomer units, polar substance added, and polymerization temperature conditions in the polymerization steps of the first and second polymer segments. The ratio of the average molecular weights of the two polymer segments can be controlled by adjusting conditions such as polymerization time, polymerization temperature, amount of monomer added, and amount of polar substance added in the polymerization step of each polymer segment.

[0060] In a continuous polymerization method, sequential polymerization using two or more reactors with different polymerization conditions is effective for controlling the aromatic vinyl monomer units and vinyl-bonded conjugated diene monomer units to an appropriate degree of randomness in order to control the tan δ peak height within a predetermined range. Specifically, to maintain a predetermined estimated glass transition temperature, it is necessary to maintain a high amount of aromatic vinyl monomer added throughout the polymerization process while reducing the amount of bound aromatic vinyl in the first polymer segment and the amount of vinyl bonds in the bound conjugated diene. Here, if polymerization conditions such as the amount of polar substance, polymerization temperature, and polymerization concentration are set low in order to reduce the amount of bound aromatic vinyl in the first polymer segment and the amount of vinyl bonds in the bound conjugated diene, the conversion rate of the aromatic vinyl compound will be significantly reduced. If the conversion rate of the aromatic vinyl compound is insufficient, the concentration of the aromatic vinyl compound will increase in the system until the subsequent polymerization of the second polymer segment, resulting in the formation of aromatic vinyl monomer unit blocks, making it difficult to control the tan δ peak height within the predetermined range. Therefore, in order to control the tan δ peak height within a predetermined range, it is a preferred embodiment that the conversion rate of the aromatic vinyl compound at the discharge section in the step of polymerizing the first polymer segment is 70% or more, and that the remaining conjugated diene compound and aromatic vinyl compound are added immediately before polymerizing the second polymer segment. Note that the conversion rate of the aromatic vinyl compound referred to here is defined as the mass of the aromatic vinyl compound that has been consumed in the polymerization reaction and turned into a conjugated diene-based polymer relative to the total amount of the aromatic vinyl compound added at the time of measurement, as described below.

[0061] (Glass Transition Temperature) The modified conjugated diene polymer of this embodiment preferably has a measured glass transition temperature (Tg) of −62° C. or higher, more preferably −58° C. or higher, and even more preferably −55° C. or higher. The modified conjugated diene polymer of this embodiment preferably has a measured glass transition temperature of less than −25° C., more preferably −35° C. or lower, and even more preferably −40° C. or lower. When the glass transition temperature falls within the above range, the fuel-saving performance of the vulcanizate of the modified conjugated diene polymer of this embodiment tends to be even better. The modified conjugated diene polymer of this embodiment preferably has an estimated Tg calculated from the microstructure in a numerical range of −62° C. or higher and −25° C. or lower. The modified conjugated diene polymer of this embodiment that falls within this numerical range basically has a measured glass transition temperature within the above range. The glass transition temperature may be within a range that combines any of the above upper and lower limits. The glass transition temperature of the modified conjugated diene polymer can be measured in accordance with ISO 22768:2006. More specifically, the glass transition temperature is determined by recording a DSC curve by differential scanning calorimetry (DSC) while increasing the temperature within a predetermined temperature range, and the inflection point of the DSC curve is taken as the glass transition temperature. Specifically, the glass transition temperature can be measured by the method described in the Examples below. The modified conjugated diene polymer of this embodiment may contain plasticizing components such as resins and process oils described below, but these components must be removed in the DSC measurement to determine the Tg of the modified conjugated diene copolymer of this embodiment.

[0062] The measured glass transition temperature of a modified conjugated diene polymer varies depending on the amount of bound aromatic vinyl monomer units in the modified conjugated diene polymer and the amount of vinyl bonds in the bound conjugated diene. Specifically, the glass transition temperature increases when the amount of bound aromatic vinyl monomer units and the amount of vinyl bonds in the bound conjugated diene are increased, whereas the glass transition temperature decreases when the amount of bound aromatic vinyl monomer units and the amount of vinyl bonds in the bound conjugated diene are decreased.

[0063] (Weight-average molecular weight) The modified conjugated diene polymer of the present embodiment has a weight-average molecular weight (Mw) measured by GPC measurement method of 70×10 ４or more, preferably 75×10 ４ More preferably, 80×10 ４ or more, and more preferably 85×10 ４ When the weight average molecular weight measured by GPC measurement method is within the above range, the vulcanizate tends to have excellent abrasion resistance. In addition, the weight average molecular weight is preferably 150×10 ４ or less, and more preferably 110×10 ４ or less, and more preferably 100×10 ４ When the weight-average molecular weight satisfies the above range, the dispersibility of the filler in the vulcanized product tends to be even better and the processability tends to be excellent. The weight-average molecular weight may be set within a range that combines any of the above upper and lower limits. The weight-average molecular weight of the modified conjugated diene polymer can be measured by GPC measurement, specifically, by the method described in the examples below.

[0064] (Number Average Molecular Weight) The modified conjugated diene polymer of the present embodiment preferably has a number average molecular weight of 25×10 as measured by GPC. ４ More preferably, 30×10 ４ More preferably, 35×10 ４ When the number average molecular weight measured by GPC measurement method is within the above range, the vulcanizate tends to have excellent abrasion resistance. In addition, the number average molecular weight is preferably 80×10 ４ or less, and more preferably 70×10 ４ or less, and more preferably 50×10 ４ When the number average molecular weight satisfies the above range, the dispersibility of the filler in the vulcanizate tends to be even better and the processability tends to be excellent. The number average molecular weight may be within a range that combines any of the above upper and lower limits. The number average molecular weight of the modified conjugated diene polymer can be measured by GPC measurement, and can be measured by the method described in the examples below.

[0065] The weight average molecular weight and number average molecular weight of the modified conjugated diene polymer can be controlled within the above-mentioned ranges by adjusting the ratio of the amount of polymerization initiator used to the amount of monomer used, the type and amount of branching agent used, the type and amount of coupling agent used, the shape of the polymerization reactor, the stirring strength, the residence time of the polymer solution, etc.

[0066] (Molecular Weight Distribution) The molecular weight distribution of the modified conjugated diene polymer of this embodiment is expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn). The modified conjugated diene polymer of this embodiment preferably has a molecular weight distribution of 1.7 or more. Modified conjugated diene polymers with a molecular weight distribution in this range tend to have better processability when vulcanized. The molecular weight distribution of the modified conjugated diene polymer of this embodiment is more preferably 1.8 or more, and even more preferably 2.0 or more. The upper limit is preferably 2.5 or less, more preferably 2.2 or less, and even more preferably 2.1 or less. The molecular weight distribution may be within a range that combines the above upper and lower limits in any combination.

[0067] (Mooney Viscosity) The modified conjugated diene polymer of this embodiment has a Mooney viscosity measured at 100°C of preferably 50 or more and 180 or less, more preferably 70 or more and 160 or less, and even more preferably 90 or more and 140 or less. When the Mooney viscosity of the modified conjugated diene polymer of this embodiment is within the above range, the processability during vulcanization and the abrasion resistance of the vulcanizate tend to be further improved. The Mooney viscosity of the modified conjugated diene polymer can be measured by the method described in the Examples below. The Mooney viscosity of the modified conjugated diene polymer of this embodiment can be controlled to be within the above numerical range by adjusting the amount of polymerization initiator used, the type and amount of branching agent and modifier used, and the type and amount of plasticizer added.

[0068] (Degree of Branching (Bn)) From the viewpoints of fuel economy performance, processability, abrasion resistance, and tensile properties, the modified conjugated diene polymer of this embodiment preferably has a degree of branching (Bn) of 7 or more as measured by a GPC-light scattering method with a viscosity detector (hereinafter also simply referred to as the degree of branching (Bn)). In general, the degree of branching (Bn) is an index that represents the branched structure of a polymer. A degree of branching (Bn) of 7 or more means that the modified conjugated diene polymer of this embodiment has five or more side polymer chains substantially relative to the longest polymer main chain.

[0069] Here, "branched" means that a polymer chain is formed by bonding to another polymer chain. Furthermore, "degree of branching (Bn)" is the number of polymer chains that are bonded directly or indirectly to the longest polymer main chain. In other words, not only the side chains bonded to the longest polymer chain but also the number of branches of the side chains is taken into consideration, if the side chain is further branched. Therefore, if one polymer chain is bonded to the longest polymer chain as a side chain, and another polymer chain is further bonded to that side chain, the degree of branching is 2.

[0070] The degree of branching (Bn) of the modified conjugated diene polymer is defined as g'=6Bn / {(Bn+1)(Bn+2)}, where g' is a shrinkage factor measured by GPC-light scattering method with a viscosity detector.

[0071] In general, branched polymers tend to have smaller molecular sizes compared to linear polymers having the same absolute molecular weight. Here, "molecular size" refers to the volume substantially occupied by the molecule. The contraction factor (g') represents the relative molecular size of a target polymer and is an index of the ratio of the molecular size of the target polymer to the molecular size of a linear polymer having the same absolute molecular weight as the target polymer. In other words, when the degree of branching of a polymer is high, its size becomes relatively small, and therefore the contraction factor (g') tends to be small.

[0072] Here, since it is known that there is a correlation between the molecular size of a polymer and the ratio of intrinsic viscosity, in this embodiment, the shrinkage factor (g') is defined as the ratio of intrinsic viscosities. That is, the shrinkage factor (g') is the ratio of the intrinsic viscosity [η ０ ] to the intrinsic viscosity [η] of the target polymer ([η] / [η ０ ]).

[0073] The intrinsic viscosity of the linear polymer [η ０ ]is [η ０ ]=10 －３．４９８ M ０．７１１ It is known that the following relationship holds. In this formula, M is the absolute molecular weight measured by the light scattering method described in the Examples below. Therefore, the shrinkage factor (g') and the degree of branching (Bn) can be determined by measuring the absolute molecular weight and intrinsic viscosity of a target polymer by GPC-light scattering measurement with a viscosity detector. The calculated degree of branching (Bn) accurately represents the number of polymer chains that are directly or indirectly bonded to each other with respect to the longest polymer main chain.

[0074] The calculated degree of branching (Bn) is an index expressing the branching structure of the modified conjugated diene polymer. For example, in the case of a typical four-branched star polymer (four polymer chains connected to the center), two polymer chain arms are bonded to the longest highly branched main chain structure, and the degree of branching (Bn) is evaluated as 2. In the case of a typical eight-branched star polymer, six polymer chain arms are bonded to the longest highly branched main chain structure, and the degree of branching (Bn) is evaluated as 6. The modified conjugated diene polymer of this embodiment preferably has a degree of branching (Bn) of 7 or more, which means that the modified conjugated diene polymer has the same branching as a nine-branched star polymer structure.

[0075] Here, "branch" refers to a structure formed by direct or indirect bonding of one polymer to another polymer, and "degree of branching (Bn)" refers to the number of polymers that are directly or indirectly bonded to each other in the longest main chain structure.

[0076] By having a branching degree (Bn) of 7 or more, the modified conjugated diene polymer of this embodiment has excellent processability when vulcanized, and when vulcanized, it has excellent fuel economy and wear resistance. Generally, an increase in absolute molecular weight tends to deteriorate processability. However, by having a branching degree (Bn) of 7 or more, the increase in viscosity when vulcanized, which accompanies an increase in absolute molecular weight, is significantly suppressed. For example, this allows the polymer to be thoroughly mixed with silica or the like during the kneading process, making it possible to disperse silica around the modified conjugated diene polymer. As a result, for example, by setting the molecular weight of the modified conjugated diene polymer to be large, it is possible to improve abrasion resistance and breaking strength, and by thoroughly kneading the polymer, it is possible to disperse silica around the polymer, allowing the functional groups to act and / or react, thereby enabling the polymer to have practically sufficient fuel economy and wet grip performance.

[0077] Furthermore, in the modified conjugated diene polymer of the present embodiment, the tan δ peak height in a tan δ peak graph as a function of temperature derived from the dynamic viscoelasticity analysis based on the above-mentioned <Condition 1> is in the range of 0.90 to 1.45, and the degree of branching (Bn) is 7 or more, so that the fuel saving performance and wet grip performance of the vulcanizate are further improved.

[0078] The modified conjugated diene polymer of the present embodiment has a degree of branching (Bn) of preferably at least 7, more preferably at least 8, and even more preferably at least 10. A modified conjugated diene polymer having a degree of branching (Bn) within this range tends to have excellent processability when made into a vulcanizate.

[0079] The upper limit of the degree of branching (Bn) of the modified conjugated diene polymer of the present embodiment is not particularly limited and may be equal to or greater than the detection limit, but is preferably equal to or less than 84, more preferably equal to or less than 80, even more preferably equal to or less than 57, and still more preferably equal to or less than 20. When the modified conjugated diene polymer of the present embodiment has a degree of branching (Bn) of 84 or less, it tends to have excellent abrasion resistance and tensile properties when vulcanized.

[0080] The degree of branching (Bn) of the modified conjugated diene polymer can be controlled to 7 or more by combining the amount of branching agent and the amount of terminal coupling agent added, which will be described later. Specifically, the degree of branching can be controlled by adjusting the number of functional groups of the branching agent, the amount of branching agent added, the timing of adding the branching agent, the functionality of the coupling agent or nitrogen atom-containing modifier, and the amount of coupling agent or nitrogen atom-containing modifier added. More specifically, the degree of branching can be controlled to 7 or more by producing the modified conjugated diene polymer using the method described in the method for producing the modified conjugated diene polymer, which will be described later.

[0081] (Main Chain Branched Structure) In order to control the degree of branching, the modified conjugated diene polymer of this embodiment preferably has a main chain branched structure. When the modified conjugated diene polymer of this embodiment has a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, the main chain branched structure preferably has two or more branching points, more preferably three or more branching points, and even more preferably four or more branching points at the branching points.

[0082] Furthermore, the branch points forming the main chain branch structure preferably have at least two or more polymer chains, more preferably have three or more polymer chains that are not the main chain, and even more preferably have four or more polymer chains that are not the main chain.

[0083] In particular, in the case of a main chain branched structure formed of a vinyl monomer containing an alkoxysilyl group or a halosilyl group, when signal detection is performed by 29Si-NMR, a peak derived from the main chain branched structure is detected in the range of −45 ppm to −65 ppm, more specifically in the range of −50 ppm to −60 ppm.

[0084] (Star Polymer Structure) The modified conjugated diene-based polymer of the present embodiment preferably has a star polymer structure, and the number of branches derived from the star polymer structure is preferably 3 or more, more preferably 4 or more, even more preferably 6 or more, and still more preferably 8 or more.

[0085] The modified conjugated diene polymer of this embodiment is preferably a modified conjugated diene polymer having a star polymer structure with three or more branches, and at least one branched chain of the star structure preferably has a moiety derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and the moiety derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group preferably has an additional main chain branch structure. Regarding a method for obtaining a modified conjugated diene polymer having such a structure, the "star polymer structure" can be formed by adjusting the number of functional groups of the coupling agent and the amount of the coupling agent added, and the "main chain branch structure" can be controlled by adjusting the number of functional groups of the branching agent, the amount of the branching agent added, and the timing of adding the branching agent.

[0086] To obtain a modified conjugated diene polymer having a three or more branched star macromolecular structure, in which at least one branched chain of the star structure has a portion derived from a vinyl monomer containing an alkoxysilyl group or a halosilyl group, and in which the portion derived from the vinyl monomer containing the alkoxysilyl group or the halosilyl group has a further main chain branched structure, for example, an organolithium compound can be used as a polymerization initiator to carry out polymerization, and during or after polymerization, a branching agent that imparts specific branching points is added, and after polymerization is continued, modification is carried out with a coupling agent that imparts a specific branching rate. Such means for controlling the polymerization conditions will be described in the production method shown in the Examples below.

[0087] (Details of Main Chain Branching Structure) In the modified conjugated diene polymer of this embodiment, the moiety derived from the vinyl monomer containing an alkoxysilyl group or a halosilyl group is preferably a monomer unit based on a compound represented by the following general formula (1) or (2), and the polymer chain preferably has a branching point due to the monomer unit based on the compound represented by the following formula (1) or (2). The modified conjugated diene polymer is more preferably a modified conjugated diene polymer obtained using a coupling agent, and even more preferably a modified conjugated diene polymer in which at least one end of the modified conjugated diene polymer has been modified with a nitrogen atom-containing group. The coupling agent may also function as the modifier described below.

[0088]

[0089]

[0090] In formula (1), R １ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, which may partially have a branched structure. ２ ~R ３ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and may partially have a branched structure. １ ~R ３ are each independent. １ represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3. In formula (2), R ２ ~R ５ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and may partially have a branched structure. ２ ~R ５ are each independent. ２ ~X ３ represent independent halogen atoms. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3. a represents an integer of 0 to 2, b represents an integer of 0 to 3, and c represents an integer of 0 to 3. (a+b+c) represents 3.

[0091] The modified conjugated diene polymer of the present embodiment is a polymer represented by the formula (1), １ is a hydrogen atom and m = 0. This tends to increase the number of branches, and to provide improved wear resistance and processability.

[0092] The modified conjugated diene polymer of the present embodiment is preferably a modified conjugated diene polymer having a monomer unit based on the compound represented by formula (2) in which m = 0 and b = 0. This tends to provide improved wear resistance and processability.

[0093] The modified conjugated diene polymer of the present embodiment is preferably a modified conjugated diene polymer having monomer units based on the compound represented by formula (2) in which m = 0, l = 0, n = 3, a = 0, b = 0, and c = 3. This tends to provide improved wear resistance and processability.

[0094] In addition, the modified conjugated diene polymer of the present embodiment may be a modified conjugated diene polymer represented by the formula (1), １ is a hydrogen atom, m = 0, 1 = 0, and n = 3. This tends to improve the modification rate and branching degree described below, and to provide effects of improving fuel economy performance, abrasion resistance, and processability.

[0095] (Branching Agent) When constructing a main chain branched structure in the modified conjugated diene polymer of the present embodiment, it is preferable to use a branching agent having a structure represented by the following formula (1) or formula (2) as the branching agent.

[0096]

[0097]

[0098] In formula (1), R １ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and may partially have a branched structure. ２ ~R ３ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and may partially have a branched structure. １ ~R ３ are each independent. １represents an independent halogen atom. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3. In formula (2), R ２ ~R ５ are each independently an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms, and may partially have a branched structure. ２ ~R ５ are each independent. ２ ~X ３ represent independent halogen atoms. m represents an integer of 0 to 2, n represents an integer of 0 to 3, and l represents an integer of 0 to 3. (m+n+l) represents 3. a represents an integer of 0 to 2, b represents an integer of 0 to 3, and c represents an integer of 0 to 3. (a+b+c) represents 3.

[0099] The branching agent used to construct the main chain branched structure of the modified conjugated diene polymer of the present embodiment is preferably a branching agent represented by R １ is a hydrogen atom and m=0.

[0100] Furthermore, from the viewpoint of improving the degree of branching, the branching agent used to construct the main chain branched structure of the modified conjugated diene polymer of the present embodiment is preferably a compound in which m=0 and b=0 in the above formula (2).

[0101] In addition, the branching agent used to construct the main chain branched structure of the modified conjugated diene polymer of the present embodiment is, from the viewpoint of continuity of polymerization and improvement of the modification rate and branching degree, R １ is a hydrogen atom, m=0, l=0, and n=3.

[0102] Furthermore, from the viewpoint of improving the modification rate and the degree of branching, the branching agent used in constructing the main chain branched structure of the modified conjugated diene-based polymer of the present embodiment is preferably a compound in which m=0, l=0, n=3, a=0, b=0, and c=3 in the above formula (2).

[0103] Examples of the branching agent represented by the formula (1) include, but are not limited to, trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, phenyl)silane, trimethoxy(2-vinylphenyl)silane, triethoxy(2-vinylphenyl)silane, tripropoxy(2-vinylphenyl)silane, tributoxy(2-vinylphenyl)silane, triisopropoxy(2-vinylphenyl)silane, dimethoxymethyl(4-vinylphenyl)silane, diethoxymethyl(4-vinylphenyl)silane, dipropoxymethyl(4-vinylphenyl)silane, dibutoxymethyl(4-vinylphenyl)silane, diisopropoxymethyl(4-vinylphenyl)silane, and the like.

[0104] Further, for example, dimethoxymethyl(3-vinylphenyl)silane, diethoxymethyl(3-vinylphenyl)silane, dipropoxymethyl(3-vinylphenyl)silane, dibutoxymethyl(3-vinylphenyl)silane, diisopropoxymethyl(3-vinylphenyl)silane, dimethoxymethyl(2-vinylphenyl)silane, diethoxymethyl(2-vinylphenyl)silane, dipropoxymethyl(2-vinylphenyl)silane, dibutoxymethyl(2-vinylphenyl)silane, diisopropoxymethyl(2-vinylphenyl)silane, dimethylmethoxy(4-vinylphenyl)silane, dimethylethoxy(4-vinylphenyl)silane, dimethylpropoxy(4-vinylphenyl)silane, (4-vinylphenyl)silane, dimethylbutoxy(4-vinylphenyl)silane, dimethylisopropoxy(4-vinylphenyl)silane, dimethylmethoxy(3-vinylphenyl)silane, dimethylethoxy(3-vinylphenyl)silane, dimethylpropoxy(3-vinylphenyl)silane, dimethylbutoxy(3-vinylphenyl)silane, dimethylisopropoxy(3-vinylphenyl)silane, dimethylmethoxy(2-vinylphenyl)silane, dimethylethoxy(2-vinylphenyl)silane, dimethylpropoxy(2-vinylphenyl)silane, dimethylbutoxy(2-vinylphenyl)silane, dimethylisopropoxy(2-vinylphenyl)silane, and the like.

[0105] Further, for example, trimethoxy(4-isopropenylphenyl)silane, triethoxy(4-isopropenylphenyl)silane, tripropoxy(4-isopropenylphenyl)silane, tributoxy(4-isopropenylphenyl)silane, triisopropoxy(4-isopropenylphenyl)silane, trimethoxy(3-isopropenylphenyl)silane, triethoxy(3-isopropenylphenyl)silane, tripropoxy(3-isopropenylphenyl)silane, tributoxy(3-isopropenylphenyl)silane, triisoprop hydroxy(3-isopropenylphenyl)silane, trimethoxy(2-isopropenylphenyl)silane, triethoxy(2-isopropenylphenyl)silane, tripropoxy(2-isopropenylphenyl)silane, tributoxy(2-isopropenylphenyl)silane, triisopropoxy(2-isopropenylphenyl)silane, dimethoxymethyl(4-isopropenylphenyl)silane, diethoxymethyl(4-isopropenylphenyl)silane, dipropoxymethyl(4-isopropenylphenyl)silane, dibutoxymethyl(4-isopropenylphenyl)silane Diisopropoxymethyl(4-isopropenylphenyl)silane, dimethoxymethyl(3-isopropenylphenyl)silane, diethoxymethyl(3-isopropenylphenyl)silane, dipropoxymethyl(3-isopropenylphenyl)silane, dibutoxymethyl(3-isopropenylphenyl)silane, diisopropoxymethyl(3-isopropenylphenyl)silane, dimethoxymethyl(2-isopropenylphenyl)silane, diethoxymethyl(2-isopropenylphenyl)silane, dipropoxy methyl(2-isopropenylphenyl)silane, dibutoxymethyl(2-isopropenylphenyl)silane, diisopropoxymethyl(2-isopropenylphenyl)silane, dimethylmethoxy(4-isopropenylphenyl)silane, dimethylethoxy(4-isopropenylphenyl)silane, dimethylpropoxy(4-isopropenylphenyl)silane, dimethylbutoxy(4-isopropenylphenyl)silane, dimethylisopropoxy(4-isopropenylphenyl)silane, dimethylmethoxy(3-isopropenylphenyl)silane,Examples of such silane include dimethylethoxy(3-isopropenylphenyl)silane, dimethylpropoxy(3-isopropenylphenyl)silane, dimethylbutoxy(3-isopropenylphenyl)silane, dimethylisopropoxy(3-isopropenylphenyl)silane, dimethylmethoxy(2-isopropenylphenyl)silane, dimethylethoxy(2-isopropenylphenyl)silane, dimethylpropoxy(2-isopropenylphenyl)silane, dimethylbutoxy(2-isopropenylphenyl)silane, and dimethylisopropoxy(2-isopropenylphenyl)silane.

[0106] Further examples include trichloro(4-vinylphenyl)silane, trichloro(3-vinylphenyl)silane, trichloro(2-vinylphenyl)silane, tribromo(4-vinylphenyl)silane, tribromo(3-vinylphenyl)silane, tribromo(2-vinylphenyl)silane, dichloromethyl(4-vinylphenyl)silane, dichloromethyl(3-vinylphenyl)silane, dichloromethyl(2-vinylphenyl)silane, dibromomethyl(4-vinylphenyl)silane, dibromomethyl(3-vinylphenyl)silane, dibromomethyl(2-vinylphenyl)silane, dimethylchloro(4-vinylphenyl)silane, dimethylchloro(3-vinylphenyl)silane, dimethylchloro(2-vinylphenyl)silane, dimethylbromo(4-vinylphenyl)silane, dimethylbromo(3-vinylphenyl)silane, and dimethylbromo(2-vinylphenyl)silane.

[0107] Among these, trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, and trichloro(4-vinylphenyl)silane are preferred, and trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, and triisopropoxy(4-vinylphenyl)silane are more preferred.

[0108] Examples of the branching agent represented by formula (2) include, but are not limited to, 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-tripropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, 1,1-bis(4-triisopropoxysilylphenyl)ethylene, 1,1-bis(3-trimethoxysilylphenyl)ethylene, 1,1-bis(3-triethoxysilylphenyl)ethylene, 1,1-bis(3-trippropoxysilylphenyl)ethylene, 1,1-bis(3-tripentoxysilylphenyl)ethylene, 1,1-bis(3-triisopropoxysilylphenyl)ethylene, 1,1-bis(2 ... Examples thereof include 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(2-triethoxysilylphenyl)ethylene, 1,1-bis(3-tripropoxysilylphenyl)ethylene, 1,1-bis(2-tripentoxysilylphenyl)ethylene, 1,1-bis(2-triisopropoxysilylphenyl)ethylene, 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dipropylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dimethylethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylethoxysilyl)phenyl)ethylene, and 1,1-bis(4-(dipropylethoxysilyl)phenyl)ethylene.

[0109] Among these, 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-tripropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, and 1,1-bis(4-triisopropoxysilylphenyl)ethylene are preferred, and 1,1-bis(4-trimethoxysilylphenyl)ethylene is more preferred.

[0110] (Modification Ratio) The modified conjugated diene polymer of this embodiment has a modification ratio of 60% or more. In this specification, the term "modification ratio" refers to the mass content, expressed as a percentage, of a modified conjugated diene polymer component having a specific functional group in the polymer molecule that has affinity or binding reactivity with a filler relative to the total amount of the mixture when a mixture of a modified conjugated diene polymer and an unmodified conjugated diene polymer is obtained by modifying a conjugated diene polymer with a nitrogen atom-containing modifying agent. Therefore, when the specific functional group contains a nitrogen atom, the term "modification ratio" refers to the mass ratio of the nitrogen-containing modified conjugated diene polymer relative to the total amount of the mixture. In this specification, the term "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. For example, when a conjugated diene polymer containing a modified conjugated diene polymer is obtained by reacting a nitrogen atom-containing modifying agent with the terminal end of a conjugated diene polymer, the modification rate is the mass ratio of the modified conjugated diene polymer having a nitrogen atom-containing functional group resulting from the nitrogen atom-containing modifying agent to the total amount of the modified conjugated diene polymer.

[0111] The modified conjugated diene polymer of this embodiment is preferably modified at the end of the second polymer segment. By bonding to the filler at the end of the second polymer segment, which has a high glass transition temperature, a vulcanizate with better wet grip performance tends to be obtained.

[0112] The modification rate can be measured by a method using chromatography that can separate functional group-containing modified components from unmodified components. Examples of such chromatography methods include a method using a gel permeation chromatography column packed with a polar substance such as silica that adsorbs specific functional groups, and quantifying the unadsorbed components using an internal standard for comparison. More specifically, the modification rate can be obtained by measuring the amount of adsorption to the silica column from the difference between a chromatogram measured on a polystyrene-based gel column and a chromatogram measured on a silica-based column for a sample solution containing a sample and a low-molecular-weight internal standard polystyrene. More specifically, the modification rate can be measured by the method described in the Examples below.

[0113] In the modified conjugated diene polymer of this embodiment, the modification rate can be controlled by adjusting the amount of modifier added and the reaction method. For example, the above modification rate can be achieved by combining a method of polymerization using an organolithium compound having at least one nitrogen atom in the molecule as a polymerization initiator, which will be described later, a method of copolymerizing a monomer having at least one nitrogen atom in the molecule, and a method of using a modifier of the structural formula described later, and controlling the polymerization conditions.

[0114] From the viewpoint of fuel-saving performance of the vulcanizate, the modified conjugated diene polymer of the present embodiment has a modification rate of 60% or more, preferably 65% ​​or more, and more preferably 70% or more.

[0115] <Modifying Agent Having a Nitrogen Atom> Examples of the modifying agent having a nitrogen atom include, but are not limited to, an amine compound having no active hydrogen, an isocyanate compound, an isothiocyanate compound, an isocyanuric acid derivative, a carbonyl compound having a nitrogen atom, a vinyl compound having a nitrogen atom, an epoxy compound having a nitrogen atom, and an alkoxysilane compound having a nitrogen atom.

[0116] The modifying agent having a nitrogen atom is preferably an amine compound having no active hydrogen, and examples thereof include a tertiary amine compound, a protected amine compound in which the active hydrogen is substituted with a protecting group, an imine compound represented by the general formula -N=C, and an alkoxysilane compound having the nitrogen atom.

[0117] Examples of the isocyanate compound that is a modifying agent having a nitrogen atom include, but are not limited to, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate (C-MDI), phenyl isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, butyl isocyanate, and 1,3,5-benzene triisocyanate.

[0118] Examples of isocyanuric acid derivatives that are modifying agents having a nitrogen atom include, but are not limited to, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 1,3,5-tris(3-triethoxysilylpropyl)isocyanurate, 1,3,5-tri(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.

[0119] Examples of carbonyl compounds that are modifying agents having a nitrogen atom 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)benzophenone, methyl- Examples thereof include 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-methyl diethylcarbamate, N,N-diethylacetamide, N,N-dimethyl-N',N'-dimethylaminoacetamide, N,N-dimethylpicolinic acid amide, and N,N-dimethylisonicotinic acid amide.

[0120] Examples of vinyl compounds that are nitrogen atom-containing modifying agents include, but are not limited to, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-methylmaleimide, N-methylphthalimide, N,N-bistrimethylsilyl acrylamide, morpholinoacrylamide, 3-(2-dimethylaminoethyl)styrene, (dimethylamino)dimethyl-4-vinylphenylsilane, 4,4'-vinylidenebis(N,N-dimethylaniline), 4,4'-vinylidenebis(N,N-diethylaniline), 1,1-bis(4-morpholinophenyl)ethylene, and 1-phenyl-1-(4-N,N-dimethylaminophenyl)ethylene.

[0121] Examples of epoxy compounds that are nitrogen atom-containing modifiers include, but are not limited to, hydrocarbon compounds containing an epoxy group bonded to an amino group, which may further have an epoxy group bonded to an ether group. Examples of such epoxy compounds include, but are not limited to, epoxy compounds represented by the following general formula (a):

[0122]

[0123] In the formula (a), R is a divalent or higher organic group having at least one polar group selected from a divalent or higher hydrocarbon group, or a polar group having oxygen such as an ether, epoxy, or ketone, a polar group having sulfur such as a thioether or thioketone, or a polar group having nitrogen such as a tertiary amino group or an imino group.

[0124] The divalent or higher valent hydrocarbon group is a saturated or unsaturated hydrocarbon group which may be linear, branched, or cyclic, and includes an alkylene group, an alkenylene group, a phenylene group, etc. Preferably, it is a hydrocarbon group having 1 to 20 carbon atoms. Examples include methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-, m-, and p-phenylene, m- and p-xylene, and bis(phenylene)-methane.

[0125] In the formula (a), R １ , R ４ is a hydrocarbon group having 1 to 10 carbon atoms, and R １ , R ４ may be the same or different. ２ , R ５ is hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, and R ２ , R ５ may be the same or different. ３ R is a hydrocarbon group having 1 to 10 carbon atoms or a structure of the following formula (a1): １ , R ２ , R ３ may be bonded to each other to form a cyclic structure. ３ When R is a hydrocarbon group, it may be bonded to R to form a cyclic structure. ３ In the formula (a), n is an integer of 1 or more, and m is 0 or an integer of 1 or more.

[0126]

[0127] In the formula (a1), R １ , R ２ is R in the formula (a).１ , R ２ is defined similarly to R １ , R ２ may be the same or different from each other.

[0128] The epoxy compound, which is a modifying agent having a nitrogen atom-containing group, is preferably one having an epoxy group-containing hydrocarbon group, more preferably one having a glycidyl group-containing hydrocarbon group.

[0129] The epoxy group-containing hydrocarbon group bonded to an amino group or an ether group is not particularly limited, but examples thereof include a glycidylamino group, a diglycidylamino group, and a glycidoxy group. A more preferred molecular structure is an epoxy group-containing compound having a glycidylamino group or a diglycidylamino group, and a glycidoxy group, respectively, and examples thereof include compounds represented by the following general formula (a2):

[0130]

[0131] In the formula (a2), R is defined as R in the formula (a), ６ is a hydrocarbon group having 1 to 10 carbon atoms or a structure of the following formula (a3): 6 When R is a hydrocarbon group, it may be bonded to R to form a cyclic structure. In this case, R ６ In formula (a2), n is an integer of 1 or more, and m is 0 or an integer of 1 or more.

[0132]

[0133] As the epoxy compound which is a modifying agent having a nitrogen atom, a compound having one or more diglycidylamino groups and one or more glycidoxy groups in the molecule is particularly preferred.

[0134] The epoxy compound used as the nitrogen atom-containing modifying agent is not limited to the following, but examples thereof include N,N-diglycidyl-4-glycidoxyaniline, 1-N,N-diglycidylaminomethyl-4-glycidoxy-cyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidoxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-oxy diamine, 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-diglycidylorthotoluidine, and N,N-diglycidylaminomethylcyclohexane. Of these, particularly preferred are N,N-diglycidyl-4-glycidoxyaniline and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0135] From the viewpoint of effectively and reliably achieving the effects of the modified conjugated diene polymer of the present embodiment, the modifier is preferably an alkoxysilane compound having a nitrogen atom.Such modifiers include, but are not limited to, 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyltriethoxysilane, 3-morpholinopropyltrimethoxysilane, 3-piperidinopropyltriethoxysilane, 3-hexamethyleneiminopropylmethyldiethoxysilane, 3-(4-methyl-1-piperazino)propyltriethoxysilane, 1-[3-(triethoxysilyl)propyl]-3-methylhexahydropyrimidine, 3-(4-trimethylsilyl) 3-(3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyl)trimethoxysilane, 3-(3-(3-piperazino)propyltriethoxysilane, 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'-tetra(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-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(4-trimethoxysilylpropyl ... 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, and the like.

[0136] <Modifier which is an alkoxysilane compound having a nitrogen atom> The modified conjugated diene-based polymer of the present embodiment is preferably modified with an alkoxysilane compound having a nitrogen atom, that is, it preferably has a modifier residue derived from an alkoxysilane compound having a nitrogen atom.

[0137] Particularly preferred examples of the alkoxysilane compound having a nitrogen atom include the following: 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 known 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, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-to 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-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, pentakis(3-trimethoxysilylpropyl) -diethylenetriamine, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, 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-sila-2-azacyclopentane)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-tri 1-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)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.

[0138] Further, 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-propanamine, N-(1,3-dimethylbutylidene)-3-(trimethoxysilyl)-1-propanamine, N-benzylsilyl N-benzylidene-3-(triethoxysilyl)propan-1-amine, N-benzylidene-3-(trimethoxysilyl)propan-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.

[0139] Furthermore, 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-dimethylpropan-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropan-1-amine), )bis(N,N-dimethylpropan-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropan-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropan-1-amine amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine), and 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropan-1-amine).

[0140] Furthermore, 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropan-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), 3,3'-(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-diethylmethane-1-amine) Disiloxane-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) Examples of suitable siloxanes include 1,3-bis(3-(1H-imidazol-1-yl)propyl)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.

[0141] Among the modifiers having a nitrogen atom, examples of protected amine compounds in which active hydrogen is substituted with a protecting group include alkoxysilanes and compounds having a protected amine in the molecule. 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-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane silane, 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 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, and 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane.

[0142] Further, for example, N-(1,3-dimethylbutylidene)-3-methyl(dimethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-methyl(diethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(trimethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-methyl(dimethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-methyl N-ethylidene-3-(diethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(trimethoxysilyl)-1-propanamine, N-ethylidene-3-methyl(dimethoxysilyl)-1-propanamine, N-ethylidene-3-methyl(diethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(trimethoxysilyl)-1-propanamine , N-(1-methylpropylidene)-3-methyl(dimethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-methyl(diethoxysilyl)-1-propanamine, N-benzylidene-3-methyl(dimethoxysilyl)propan-1-amine, N-benzylidene-3-methyl(diethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-(triethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-(trimethoxysilyl)propan-1-amine, N- 4-methylbenzylidene-3-methyl(dimethoxysilyl)propan-1-amine, N-4-methylbenzylidene-3-methyl(diethoxysilyl)propan-1-amine, N-naphthylidene-3-(triethoxysilyl)propan-1-amine, N-naphthylidene-3-(trimethoxysilyl)propan-1-amine, N-naphthylidene-3-methyl(dimethoxysilyl)propan-1-amine, 1,1-(1,4-phenylene)bis(N-(3-methyl(dimethoxysilyl)propyl)methanamine), 1,1-(1,4-phenylene)bis(N-(3-methyl(diethoxysilyl)propyl)methanamine), 2-ethoxy-2-methyl-1-(benzylideneaminoethyl)-1-aza-2-silacyclopentane, and 2-methoxy-2-methyl-1-(methylisobutylideneaminoethyl)-1-aza-2-silacyclopentane, 1-trimethylsilyl-4-[3-(trimethoxysilyl)propyl]piperazine, and 1-trimethylsilyl-4-[3-(triethoxysilyl)propyl]piperazine.

[0143] When a coupling step is carried out in the process for producing the modified conjugated diene polymer of the present embodiment, it is more preferable to use a nitrogen atom-containing modifier represented by any one of the following formulas (A) to (D) in the coupling step. These may be used alone or in combination of two or more.

[0144]

[0145] Here, R 10 , R 11 are hydrocarbon groups having 1 to 12 carbon atoms, which may contain unsaturated bonds, and may be the same or different. 12 is a hydrocarbon group having 1 to 20 carbon atoms. 8 , R 9 are aliphatic hydrocarbon groups having 1 to 6 carbon atoms, which may contain unsaturated bonds, and may be the same or different. 7 is a hydrocarbon group containing Si, O, or N and having 1 to 20 carbon atoms which may be substituted with an organic group having no active hydrogen, and which may have an unsaturated bond. a is an integer of 1 to 3.

[0146]

[0147] In the 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 an oxygen atom, a nitrogen atom, a silicon atom, a sulfur atom, and a phosphorus atom, and having no active hydrogen. 13 , R 14 , and R 15R each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms. 16 , R 17 , R 18 , R 19 , and R 21 R each independently represents an alkyl group having 1 to 20 carbon atoms. 20 , and R 22 R each independently represents an alkylene group having 1 to 20 carbon atoms. 23 each independently represents an alkyl group or a trialkylsilyl group having 1 to 20 carbon atoms, each b independently represents an integer of 1 to 3, each c independently represents 1 or 2, i independently represents an integer of 0 to 6, j independently represents an integer of 0 to 6, k independently represents an integer of 0 to 6, and the sum of i, j, and k is an integer of 4 to 10.

[0148]

[0149] However, in formula (C), R ２4 , R ２5 , R ２6 , R ２7 , R ２8 , and R ２9 R each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms. 30 , R ３1 , and R ３2 each independently represents an alkylene group having 1 to 20 carbon atoms. 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.

[0150]

[0151] However, in formula (D), B １ and B 2 are each independently a divalent hydrocarbon group having 1 to 20 carbon atoms which may or may not contain an oxygen atom. 33 ~R 36 are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. 1 ~L 4 are each independently 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;1 and L 2 And, L 3 and L 4 may be linked together to form a ring having 1 to 5 carbon atoms, and L 1 and L 2 And, L 3 and L 4 When are linked together to form a ring, the ring formed may contain 1 to 3 heteroatoms of one or more types selected from the group consisting of N, O, and S.

[0152] Specifically, in the formula (D), B １ and B ２ are each independently an alkylene group having 1 to 10 carbon atoms; R ３3 ~R ３6 are each independently an alkyl group having 1 to 10 carbon atoms, and L 1 ~L 4 are each independently 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 may be linked together to form a ring having 1 to 3 carbon atoms, and L 1 and L 2 And, L 3 and L 4 When are linked together to form a ring, the ring formed may contain 1 to 3 heteroatoms of one or more types selected from the group consisting of N, O and S.

[0153] The modifying agent represented by formula (A) used in the coupling step includes, but is 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.

[0154] Among these, from the viewpoint of enhancing the reactivity and interaction between the modified conjugated diene-based polymer of the present embodiment and an inorganic filler such as silica, and from the viewpoint of enhancing processability, those in which a in formula (A) is 3 are preferred.

[0155] In the coupling step using the modifying agent represented by formula (A), the reaction temperature and reaction time are not particularly limited, but the reaction is preferably carried out at a temperature of 0° C. or higher and 120° C. or lower, and for 30 seconds or longer.

[0156] The amount of the modifying agent represented by formula (A) added is preferably in a range such that the total number of moles of alkoxy groups bonded to silyl groups in the compound represented by formula (A) is 0.3 to 4.0 times the number of moles of the polymerization initiator added, more preferably 0.5 to 3 times, and even more preferably 0.6 to 2.0 times. From the viewpoint of setting the molecular weight of the resulting modified conjugated diene polymer in a more preferred range, the amount is preferably 0.3 times or more, and from the viewpoint of storage stability during long-term storage, the amount is preferably 4.0 times or less.

[0157] More specifically, the amounts of the polymerization initiator and the modifier represented by formula (A) added may be adjusted so that the number of moles of the modifier represented by formula (A) is preferably 0.1 to 1.0 times the number of moles of the polymerization initiator.

[0158] In the formula (B), A is preferably represented by any one of the following formulae (I) to (IV).

[0159]

[0160] In formula (Chemical I), D １ represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. h represents an integer of 1 to 10. When there are multiple D １ are each independent of each other.

[0161]

[0162] In formula (Chemical II), D ２ represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. ３represents an alkyl group having 1 to 20 carbon atoms, and h represents an integer of 1 to 10. When a plurality of D ２ and D ３ are each independent of each other.

[0163]

[0164] In formula (III), D ４ represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. h represents an integer of 1 to 10. When there are multiple D ４ are each independent of each other.

[0165]

[0166] In formula (Chemical IV), D ５ represents a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms. h represents an integer of 1 to 10. When there are multiple D ５ are each independent of each other.

[0167] In the formula (B), when A is represented by formula (Chemical Formula I), examples of the modifying agent include, but are 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-diethoxy-1-aza

[0033] Examples of such amines include 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, and tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-propanediamine.

[0168] Further, for example, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl] tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-triethoxysilylpropyl)-1,3-propanediamine, and tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine.

[0169] Further, for example, bis(3-triethoxysilylpropyl)-bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, 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-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-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, and tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane.

[0170] Furthermore, for example, 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-propanediamine, tris(3-trimethoxysilylpropyl) 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.

[0171] Furthermore, for example, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-triethoxysilylpropyl)-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-1,3-propanediamine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris(3-triethoxysilylpropyl)-[3-(1-ethoxy-2-trimethylsilylpropyl)-bis[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-trimethylsilylpropyl) 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, 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-hexamethylenediamine, and pentakis(3-trimethoxysilylpropyl)-diethylenetriamine.

[0172] In the formula (B), when A is represented by formula (II), examples of the modifying agent include, but are 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]-(3-trimethoxysilylpropyl), bis(2-triethoxysilylpropyl)-methyl-1,3-propanediamine, tris(3-triethoxysilylpropyl)-methyl-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-propanediamine), 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.

[0173] In the formula (B), when A is represented by formula (III), examples of the modifying agent include, but are 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 ]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- bis(3-trimethoxysilylpropyl)-bis[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)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.

[0174] In the formula (B), when A is represented by formula (chemical formula IV), examples of the modifying agent include, but are 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.

[0175] The amount of the modifier represented by formula (B) to be added is preferably determined based on the ratio of the number of moles of the polymerization initiator to the number of moles of the modifier represented by formula (B) to be added, which allows the conjugated diene polymer and the modifier to react in a desired stoichiometric ratio.

[0176] More specifically, the amounts of the polymerization initiator and the coupling modifier represented by formula (B) added may be adjusted so that the ratio of the number of moles of the modifier represented by formula (B) to the number of moles of the polymerization initiator is preferably 0.012 to 1.0, more preferably 0.02 to 0.5. In this case, the number of functional groups of the modifier in formula (B) (e.g., when i and j are 2 or more and there are multiple b and c, and when b and c are equal, b×i+(c+1)×j+k) is preferably an integer of 5 to 10, more preferably an integer of 6 to 10. From the viewpoint of keeping the molecular weight of the resulting modified conjugated diene polymer in a preferred range, the ratio is preferably 0.012 or more. From the viewpoint of storage stability during long-term storage, the ratio is preferably 0.2 or less.

[0177] Examples of the modifying agent represented by 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.

[0178] Among these, from the viewpoint of enhancing the reactivity and interaction between the modified conjugated diene polymer and the inorganic filler such as silica, and from the viewpoint of enhancing processability, it is preferable that s, t, and u in the formula (C) are all 3.

[0179] The reaction temperature and reaction time in the coupling step using the coupling modifier represented by formula (C) are not limited to the following, but are preferably 0°C or higher and 120°C or lower, and the reaction is preferably carried out for 30 seconds or longer.

[0180] The amount of the modifying agent represented by formula (C) added is preferably in a range such that the total number of moles of alkoxy groups bonded to silyl groups in the compound represented by formula (C) is 0.1 to 2.0 times the number of moles of the polymerization initiator added, more preferably 0.2 to 1.0 times, and even more preferably 0.3 to 0.5 times. From the viewpoint of the molecular weight of the resulting modified conjugated diene polymer, it is preferably 0.1 times or more. Furthermore, from the viewpoint of storage stability during long-term storage, it is preferably 2.0 times or less.

[0181] The modifying agent represented by formula (D) is not limited to the following, but examples thereof include 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropan-1-amine), 3,3'-1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropan-1-amine), 3,3'-(1,1,3,3-tetrapropoxydisiloxane-1,3-diyl)bis(N,N-dimethylpropan-1-amine), 3,3'-(1,1,3,3-tetramethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine), 3,3'-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(N,N-dimethyl ...dimethylpropan-1-amine), 3,3'-(1,1,3,3-tetramethyldisiloxane-1,3-diyl)bis(N,N-dimethylpropan-1-amine), 3,3'-(1,1,3,3 methoxydisiloxane-1,3-diyl)bis(N,N-dipropylpropan-1-amine), 3,3'-(1,1,3,3-tetraethoxydisiloxane-1,3-diyl)bis(N,N-diethylpropan-1-amine), and the like.

[0182] In the coupling step using the modifying agent represented by formula (D), the reaction temperature and reaction time are not particularly limited, but the reaction is preferably carried out at a temperature of 0° C. or higher and 120° C. or lower, and for 30 seconds or longer.

[0183] The amount of the modifying agent represented by formula (D) added is preferably in a range such that the total number of moles of alkoxy groups bonded to silyl groups in the compound represented by formula (D) is 0.25 to 2.0 times the number of moles of the polymerization initiator added, more preferably 0.3 to 1 time, and even more preferably 0.35 to 0.5 times. From the viewpoint of the molecular weight of the resulting modified conjugated diene polymer and from the viewpoint of storage stability during long-term storage, it is preferably 2.0 times or less.

[0184] [Method for Producing Conjugated Diene Polymer] The method for producing a modified conjugated diene polymer of this embodiment includes a polymerization step of polymerizing at least one conjugated diene compound using a continuous reactor in which two or more reactors are connected in series and a lithium compound as a polymerization initiator, the continuous reactor having a monomer addition section for adding at least one conjugated diene compound and an aromatic vinyl compound during the polymerization step, and a coupling step of reacting the conjugated diene polymer obtained in the polymerization step with a modifier having a nitrogen atom.

[0185] (Polymerization Initiator) At least an organic monolithium compound can be used as the polymerization initiator. Examples of organic monolithium compounds include, but are not limited to, low molecular weight compounds and solubilized oligomeric organic monolithium compounds. Furthermore, examples of organic monolithium compounds include compounds having a carbon-lithium bond, a nitrogen-lithium bond, and a tin-lithium bond in the bonding mode between the organic group and the lithium. The amount of the organic monolithium compound used as the polymerization initiator is preferably determined based on the target molecular weight of the conjugated diene polymer or modified conjugated diene polymer. The amount of monomer, such as a conjugated diene compound, used relative to the amount of polymerization initiator used is related to the degree of polymerization. In other words, it tends to be related to the number-average molecular weight and weight-average molecular weight. Therefore, to increase the molecular weight, it is effective to reduce the amount of polymerization initiator used, and to decrease the molecular weight, it is effective to increase the amount of polymerization initiator used.

[0186] When introducing nitrogen atoms into a conjugated diene polymer using a polymerization initiator, the organic monolithium compound is preferably an alkyllithium compound having a substituted amino group or a dialkylaminolithium compound, from the viewpoint that it can be used as one method for introducing nitrogen atoms into a conjugated diene polymer. In this case, a conjugated diene polymer having a nitrogen atom consisting of an amino group at the polymerization initiation terminal is obtained. The substituted amino group is an amino group that does not have an active hydrogen or has a structure in which the active hydrogen is protected. Examples of alkyllithium compounds having an amino group without an active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium. Examples of alkyllithium compounds having an amino group with a structure in which the active hydrogen is protected include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium. Examples of dialkylaminolithiums 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 pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine. These organomonolithium compounds having a substituted amino group can also be used as solubilized oligomeric organomonolithium compounds by reacting them with a small amount of a polymerizable monomer, such as 1,3-butadiene, isoprene, or styrene.

[0187] The polymerization initiator may be one produced by reacting an aromatic vinyl compound and / or a conjugated diene compound having a substituted amino group with an organomonolithium compound, or may be one capable of introducing a functional group into one end of a polymer chain. The organomonolithium compound is preferably an alkyllithium compound from the viewpoints of industrial availability and ease of control of the polymerization reaction. In this case, a conjugated diene polymer having an alkyl group at the polymerization initiation end is obtained. Examples of the alkyllithium compound include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium. Examples of the alkyllithium compound include n-butyllithium and sec-butyllithium from the viewpoints of industrial availability and ease of control of the polymerization reaction. These organomonolithium compounds may be used alone or in combination of two or more. Furthermore, they may be used in combination with other organometallic compounds. Examples of the other organometallic compounds include alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds. Examples of alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds. Also included are alkaline earth metal alkoxides, sulfonates, carbonates, and amides. Examples of organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Other organometallic compounds include organoaluminum compounds.

[0188] The weight-average molecular weight of the conjugated diene polymer at the outlet of the polymerization step is controlled by the amount of polymerization initiator used relative to the conjugated diene compound and aromatic vinyl compound, and the weight-average molecular weight tends to decrease as the amount of polymerization initiator used decreases. The amount of polymerization initiator used is preferably 0.15 mol or more and 1.5 mol or less, assuming that the total mass of the conjugated diene compound and aromatic vinyl compound used is 100 kg.

[0189] (Polar Substance) In the method for producing a modified conjugated diene polymer of this embodiment, a polar substance may be added together with the polymerization initiator. The polar substance can randomly copolymerize an aromatic vinyl compound with a conjugated diene compound, and tends to be usable as a vinylating agent for controlling the microstructure of the conjugated diene portion. In addition, the polar substance tends to be effective in accelerating the polymerization reaction.

[0190] Examples of 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, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium amylate; and phosphine compounds such as triphenylphosphine. These polar substances may be used alone or in combination of two or more.

[0191] The amount of polar substance used is not particularly limited and can be selected depending on the purpose, but is preferably 0.005 mol or more and 100 mol or less per mol of the polymerization initiator.

[0192] Such polar substances can be used in an appropriate amount depending on the desired vinyl bond amount as an adjuster for the microstructure of the conjugated diene portion of the modified conjugated diene polymer of this embodiment. Many polar substances simultaneously exhibit an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and tend to be able to adjust the randomness of the aromatic vinyl monomer units and conjugated diene monomer units in each polymer segment.

[0193] (Polymerization Step) In the method for producing a modified conjugated diene polymer of this embodiment, the polymerization step is carried out in a continuous reactor system in which two or more reactors are connected in series, and includes a polymerization step (P1) for obtaining a first polymer segment and a polymerization step (P2) for obtaining a second polymer segment. The polymerization steps (P1) and (P2) are separated by a monomer addition section, which will be described later. The polymerization steps (P1) and (P2) can each be carried out using one or two or more connected reactors. The reactor may be a tank type or a tubular type equipped with an agitator. It is not necessary to assign the polymerization steps (P1) and (P2) to each reactor. For example, the polymerization step (P2) may be set to start downstream of the first reactor. However, from the viewpoint of ease of polymerization control, it is preferable to assign one or more reactors to each of the polymerization steps (P1) and (P2). Each reactor may have a temperature control function.

[0194] (Solid Amount) In the method for producing a modified conjugated diene polymer according to the present embodiment, the target modified conjugated diene polymer can be recovered in a predetermined solid amount. In this specification, the solid amount refers to the mass of the modified conjugated diene polymer recovered per unit time at a measurement point. The mass of the modified conjugated diene polymer includes only the polymer that has reacted with the polymerization initiator and been polymerized, and does not include unreacted conjugated diene compound, aromatic vinyl compound, solvent, etc.

[0195] (Conversion Rate) In the method for producing a modified conjugated diene polymer of this embodiment, the "conversion rate" is defined as the mass of the conjugated diene polymer that has been produced as a result of the reaction completed at the time of measurement relative to the sum of the mass of the conjugated diene compound and the mass of the aromatic vinyl compound added at the time of measurement. That is, it can be calculated using the solid amount by the following mathematical formula (2):

[0196]

[0197] Furthermore, the conversion rates of the conjugated diene compound and the aromatic vinyl compound can be calculated by the following formulas (3) and (4) using the amount of bound conjugated diene monomer units and the amount of bound aromatic vinyl monomer units in the solid content obtained by the solid content measurement.

[0198]

[0199] The conversion rate in the polymerization step (P1) is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. When the polymerization conversion rate is within the above range, the conversion rate is less likely to fluctuate due to disturbances during continuous polymerization, thereby improving production stability.

[0200] The conversion rate of the aromatic vinyl compound in the polymerization intermediate in the polymerization step (P1) is preferably 70% or more, more preferably 75% or more, and even more preferably 80% or more. If the conversion rate of the aromatic vinyl compound is not within the above range, the aromatic vinyl monomer units tend to be significantly unevenly distributed in the second polymer segment, and the tan δ peak height tends to decrease. On the other hand, if the conversion rate of the aromatic vinyl compound is within the above range, the distribution of the aromatic vinyl monomer units tends to be uniform, and the tan δ peak height tends to increase. In particular, when the amount of polar substance added is small and the amount of aromatic vinyl compound added is large, the conversion rate of the aromatic vinyl compound tends to deviate from the above range.

[0201] The conversion rate in the polymerization step (P2) is preferably 95% or more from the viewpoint of ease of polymerization control.

[0202] The conversion rate of the aromatic vinyl compound in the polymerization intermediate in the polymerization step (P1) and the conversion rate of the aromatic vinyl compound in the polymerization step (P2) can be controlled by adjusting the type and amount of polar substance added, the polymerization temperature, the concentrations of the monomer and polymerization initiator in the raw material solution, and the residence time.

[0203] In the method for producing a modified conjugated diene system of this embodiment, a first polymer segment is obtained in the polymerization step (P1), and in this polymerization step (P1), it is preferable that the reactor has 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 thereof, and a discharge section for continuously discharging a polymer solution from the end opposite to the raw material supply section.

[0204] Amount X of bound aromatic vinyl monomer units in the first polymer segment １ can be controlled by adjusting the mass ratio of the aromatic vinyl compound to the conjugated diene compound added in the polymerization step (P1).

[0205] Amount of vinyl bonds in the bonded conjugated diene of the first polymer segment Y １ can be controlled by adjusting the amount of polar substance added in the polymerization step (P1) and the polymerization temperature.

[0206] The conjugated diene polymer solution after the polymerization step (P1) is continuously distilled from the reactor and sent to the next step. In a preferred embodiment, the destination of the solution is, for example, the polymerization step (P2) of the second polymer segment described below. The starting point of the polymerization step (P2) is defined as the monomer addition section.

[0207] In the method for producing a modified conjugated diene polymer of this embodiment, it is preferable to have a monomer addition section in which a raw material compound is newly added after the polymerization step (P1), thereby having a polymerization step (P2) in which a second polymer segment having a higher vinyl bond amount in the bound conjugated diene than that synthesized in the previous polymerization step is introduced to the end of the first polymer segment.

[0208] The form of the connection between the polymerization step (P1) and the polymerization step (P2) where the monomer addition section is located is not particularly limited, but is preferably a pipe from the viewpoint of preventing backflow of the polymer solution, and more preferably between the pipes of the first and second continuous reactors. The added raw material compounds are preferably conjugated diene compounds, aromatic vinyl compounds, polar substances, etc., and from the viewpoint of the fuel-saving performance of the vulcanizate of the modified conjugated diene polymer of this embodiment, more preferably conjugated diene compounds, aromatic vinyl compounds, polar substances, and branching agents described below. An inert solvent may be added in the monomer addition section.

[0209] The lower limit of the total mass of the conjugated diene compound and aromatic vinyl compound added in the monomer addition section is preferably 10% or more, more preferably 15% or more, and even more preferably 18% or more, relative to the total mass of the conjugated diene compound and aromatic vinyl compound added throughout the polymerization process. The upper limit of the total mass of the conjugated diene compound and aromatic vinyl compound added in the monomer addition section is preferably 90% or less, more preferably 80% or less, and even more preferably 50% or less, relative to the total mass of the conjugated diene compound and aromatic vinyl compound added throughout the polymerization process. By being in the above range, the trade-off between wet grip performance and abrasion resistance tends to be more significantly improved.

[0210] Amount of bound aromatic vinyl monomer units X of the second polymer segment ２ can be controlled by adjusting the mass ratio of the aromatic vinyl compound to the conjugated diene compound additionally added in the polymerization step (P2).

[0211] Amount of vinyl bond in the bonded conjugated diene of the second polymer segment Y ２ can be controlled by adjusting the amount of the polar compound additionally added in the polymerization step (P2) and the polymerization temperature.

[0212] The conjugated diene polymer solution after the polymerization step (P2) is continuously distilled from the reactor and sent to the next step, which may be, for example, the coupling step described below.

[0213] The polymer segment ratio is controlled by adjusting the ratio of the mass of the monomer added in the polymerization step (P1) to the mass of the monomer added in the polymerization step (P2) and the conversion rates of the polymerization steps (P1) and (P2). To increase the ratio of the first polymer segment, the proportion of the monomer added in the polymerization step (P1) is increased to increase the polymerization conversion rate in the polymerization step (P1).

[0214] The production of the modified conjugated diene-based polymer of the present embodiment may include a predetermined step before or after the polymerization step (P1) or before or after the polymerization step (P2). For example, a step of synthesizing a polymer different from the first polymer segment or the second polymer segment may be included.

[0215] In the method for producing a modified conjugated diene polymer of this embodiment, the polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds, and from the viewpoint of productivity, is more preferably 0°C or higher and 120°C or lower, and even more preferably 50°C or higher and 100°C or lower. By keeping the temperature in this range, it tends to be possible to ensure a sufficient amount of the modifier reacting with the active terminals after the completion of polymerization. An even more preferable temperature is 70°C or higher and 95°C or lower.

[0216] In the method for producing a modified conjugated diene polymer of this embodiment, a high molecular weight distribution can be obtained by reducing the height (L) / diameter (D) of the tank reactor. A smaller L / D ratio increases the residence time distribution in the reactor, which increases the variation in reaction time for each polymerization initiator molecule, tending to increase the molecular weight distribution. Furthermore, the molecular weight distribution changes depending on the type of coupling agent used.

[0217] (Coupling Step) In the method for producing a modified conjugated diene polymer of this embodiment, a coupling step is carried out in which the active terminal of the conjugated diene polymer obtained through the polymer segment polymerization step is modified with a nitrogen atom-containing modifier (preferably, an alkoxysilane modifier having a nitrogen atom). In the coupling step, one of the active terminals of the conjugated diene polymer is subjected to a modification reaction with the nitrogen atom-containing modifier to obtain a modified conjugated diene polymer.

[0218] The method for producing a modified conjugated diene-based polymer of the present embodiment may include a condensation reaction step in which a condensation promoter is added to cause a condensation reaction after and / or before the coupling step.

[0219] In the method for producing a modified conjugated diene polymer of this embodiment, a deactivator and / or a neutralizing agent may be added to the polymer solution after the coupling step, as necessary. Examples of deactivators include, but are not limited to, water, and alcohols such as methanol, ethanol, and isopropanol. Examples of neutralizing agents include, but are not limited to, aqueous solutions of carboxylic acids such as stearic acid, oleic acid, and versatic acid (a mixture of highly branched carboxylic acids having 9 to 11 carbon atoms and mainly containing 10 carbon atoms), inorganic acids, and carbon dioxide gas.

[0220] From the viewpoint of preventing gel formation after polymerization and improving stability during processing, it is preferable to add a rubber stabilizer to the modified conjugated diene polymer of this embodiment. The rubber stabilizer is not limited to the following and any known stabilizer can be used, but preferred examples include 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.

[0221] (Step of Obtaining Polymer from Polymer Solution) The method for producing a modified conjugated diene polymer of this embodiment may include a step of obtaining the obtained modified conjugated diene polymer from the polymer solution. As such a method, a known method can be used, and for example, the following method may be used. Examples of such a method include a method in which the solvent is separated by steam stripping or the like, and then the modified conjugated diene polymer is filtered, and then dehydrated and dried to obtain a modified conjugated diene polymer; a method in which the modified conjugated diene polymer is obtained by concentrating the polymer in a flashing tank and then devolatilizing it using a vent extruder or the like; and a method in which the modified conjugated diene polymer is obtained by directly devolatilizing it using a drum dryer or the like.

[0222] (Step of Obtaining Extended Conjugated Diene Polymer) In the method for producing a modified conjugated diene polymer of this embodiment, at least one selected from the group consisting of extended oil, liquid rubber, and resin may be added to the produced modified conjugated diene polymer to obtain an extended-modified conjugated diene polymer. The extended-modified conjugated diene polymer includes not only oil-extended modified conjugated diene polymers containing oil, but also those containing liquid polybutadiene or various resins other than oil. This can further improve the processability of the modified conjugated diene polymer.

[0223] The method for adding an extender oil to a modified conjugated diene polymer is not limited to the following methods, but a preferred method involves adding an extender oil to a modified conjugated diene polymer solution, mixing, and then desolvating the resulting extended polymer solution. Examples of extender oils include aroma oils, naphthenic oils, paraffin oils, and vegetable oils. The vegetable oil can be made from an oil selected from the group consisting of linseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, castor oil, tung oil, pine oil, sunflower oil, palm oil, olive oil, coconut oil, peanut oil, and grapeseed oil. Among these, from the viewpoints of environmental safety, oil bleed prevention, and wet grip properties, aroma substitute oils having a polycyclic aromatic (PCA) content of 3% by mass or less according to the IP346 method are preferred. Examples of aroma substitute oils include TDAE (Treated Distillate Aromatic Extracts) and MES (Mild Extraction Solvate) as shown in Kautschuk Gummi Kunststoffe 52(12)799(1999), as well as RAE (Residual Aromatic Extracts).

[0224] Examples of liquid rubbers include, but are not limited to, liquid polybutadiene and liquid styrene-butadiene rubber. Examples of resins 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, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, monoolefin oligomers, diolefin oligomers, hydrogenated aromatic hydrocarbon resins, cyclic aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated tung oil resins, hydrogenated oil resins, and esters of hydrogenated oil resins with monofunctional or polyfunctional alcohols. These resins may be used alone or in combination. In the case of hydrogenation, all of the unsaturated groups may be hydrogenated, or some of them may remain. The amount of at least one selected from the group consisting of extender oil, liquid rubber, and resin to be added 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-based polymer of the present embodiment.

[0225] [Rubber Composition] The modified conjugated diene polymer of this embodiment can be made into a rubber composition (hereinafter sometimes referred to as the rubber composition of this embodiment) by adding a filler. A rubber composition using the modified conjugated diene polymer of this embodiment includes a rubber component containing the modified conjugated diene polymer of this embodiment described above and 5.0 parts by mass to 150 parts by mass of a filler per 100 parts by mass of the rubber component. The rubber component preferably contains 10 parts by mass or more of the modified conjugated diene polymer of this embodiment per 100 parts by mass of the total rubber component. By dispersing a filler in the rubber component containing the modified conjugated diene polymer of this embodiment, a rubber composition can be obtained that has even better processability during vulcanization and that produces a vulcanizate with even better low hysteresis loss, fracture properties, and abrasion resistance. Furthermore, by including the modified conjugated diene polymer of this embodiment in a predetermined proportion in the rubber component, processability and abrasion resistance tend to be further improved.

[0226] Examples of fillers include, but are not limited to, silica-based inorganic fillers, carbon black, metal oxides, and metal hydroxides. Among these, silica-based inorganic fillers are preferred. In particular, when the rubber composition is used for vulcanized rubber applications such as tires, automobile parts such as anti-vibration rubber, and shoes, it is particularly preferred to contain a silica-based inorganic filler. Such fillers may be used alone or in combination of two or more.

[0227] The silica-based inorganic filler is not particularly limited and known fillers can be used, but SiO ２ or Si ３ Solid particles containing Al as a constituent unit are preferred, and SiO ２ or Si ３ Solid particles containing Al as the main component of the structural units are more preferred. Here, the main component refers to a component contained in the silica-based inorganic filler in an amount of more than 50% by mass, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0228] Examples of silica-based inorganic fillers include, but are not limited to, inorganic fibrous materials such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. Surface-hydrophobized silica-based inorganic fillers and mixtures of silica-based inorganic fillers with non-silica-based inorganic fillers may also be used. Among these, silica or glass fiber is preferred, and silica is more preferred, from the viewpoint of further improving the strength and abrasion resistance of the rubber composition of this embodiment. Examples of silica include, but are not limited to, dry silica, wet silica, and synthetic silicate silica. Among these silicas, wet silica is preferred from the viewpoint of further improving the breaking strength of the rubber composition.

[0229] From the viewpoint of more reliably obtaining a rubber composition having practically good abrasion resistance and breaking strength, the nitrogen adsorption specific surface area of ​​the silica-based inorganic filler determined by the BET adsorption method is 100 m ２ / g or more 300m ２ / g or less, and ２ / g or more 250m ２ / g or less. If necessary, a relatively small specific surface area (for example, a specific surface area of ​​200 m ２ / g) silica-based inorganic filler and a relatively large specific surface area (e.g., 200 m ２ In particular, silica-based inorganic fillers having a relatively large specific area (for example, 200 m / g or more) may be used in combination. ２ When a silica-based inorganic filler (at least 1000 saturates) is used, the dispersibility of silica in the rubber composition of the present embodiment is further improved, which tends to result in a rubber composition having even better abrasion resistance, fracture strength, and low hysteresis loss.

[0230] Examples of carbon black include, but are not limited to, carbon blacks of various classes such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon blacks having a nitrogen adsorption specific surface area of ​​50 m or more as determined by the BET adsorption method are preferred. ２ Carbon black having a carbon absorption of 80 mL / 100 g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or less is preferred.

[0231] The metal oxides include those represented by 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.) As long as the solid particles have as a main component a structural unit, there is no particular limitation, but examples thereof include alumina, titanium oxide, magnesium oxide, and zinc oxide.

[0232] The metal hydroxide is not particularly limited, but examples thereof include aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0233] The content of the filler in the rubber composition using the modified conjugated diene polymer 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, per 100 parts by mass of the rubber component. When the filler satisfies the above range, the rubber composition tends to have even more excellent processability during vulcanization, and the vulcanizate thereof tends to have even more excellent low hysteresis loss, fracture properties, and abrasion resistance.

[0234] From the viewpoint of reliably imparting the performance required for applications such as tires, such as dry grip performance and electrical conductivity, the rubber composition using the modified conjugated diene polymer of this embodiment preferably contains carbon black in an amount of 0.5 parts by mass to 100 parts by mass per 100 parts by mass of the rubber component containing the conjugated diene polymer of this embodiment. From the same viewpoint, the rubber composition preferably contains carbon black in an amount of 3.0 parts by mass to 100 parts by mass, and even more preferably 5.0 parts by mass to 50 parts by mass, per 100 parts by mass of the rubber component containing the modified conjugated diene polymer of this embodiment.

[0235] The rubber composition using the modified conjugated diene polymer of this embodiment may further contain a silane coupling agent. By including a silane coupling agent in the rubber composition, the interaction between the rubber component and the filler can be further improved. Examples of silane coupling agents include, but are not limited to, compounds having a sulfur bond moiety and an alkoxysilyl group or silanol group 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.

[0236] In the rubber composition using the modified conjugated diene polymer of this embodiment, the content of the silane coupling agent is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and even more preferably 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 improved.

[0237] The rubber composition using the modified conjugated diene polymer of this embodiment may contain, as a rubber component, a rubbery polymer other than the modified conjugated diene polymer of this embodiment (hereinafter simply referred to as a "rubbery polymer"). Examples of the rubbery polymer 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. Examples of the rubbery polymer include, but are not limited to, styrene-based elastomers such as butadiene rubber and hydrogenated products thereof, isoprene rubber and hydrogenated products thereof, styrene-butadiene rubber and hydrogenated products thereof, styrene-butadiene block copolymers and hydrogenated products thereof, and styrene-isoprene block copolymers and hydrogenated products thereof, as well as acrylonitrile-butadiene rubber and hydrogenated products thereof. 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. Natural rubber includes, but is not limited to, smoked sheets RSS3 to 5, SMR, and epoxidized natural rubber.

[0238] The rubbery polymer may be a modified rubber to which a polar functional group such as a hydroxyl group, an amino group, etc. When the rubber composition using the modified conjugated diene polymer of the present embodiment is used as a material for a tire, the rubbery polymer is preferably at least one selected from the group consisting of butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber.

[0239] From the viewpoint of the balance between the abrasion resistance, breaking strength, low hysteresis loss, and processability of the rubber composition, the mass average molecular weight of the rubber polymer is preferably 2,000 to 2,000,000, and more preferably 5,000 to 1,500,000. Furthermore, a low molecular weight rubber polymer, so-called liquid rubber, can also be used as the rubber polymer. These rubber polymers may be used alone or in combination of two or more.

[0240] When a rubber composition using the modified conjugated diene polymer of this embodiment further contains the above-mentioned rubbery polymer in addition to the modified conjugated diene polymer of this embodiment, the content ratio (mass ratio) of the modified conjugated diene polymer to the rubbery polymer (modified conjugated diene polymer / rubbery polymer) is preferably 10 / 90 to 100 / 0, more preferably 20 / 80 to 90 / 10, and even more preferably 30 / 70 to 80 / 20. That is, the rubber component preferably contains 10 to 100 parts by mass, more preferably 20 to 90 parts by mass, and even more preferably 30 to 80 parts by mass of the modified conjugated diene polymer of this embodiment per 100 parts by mass of the total rubber component. When the proportion of the modified conjugated diene polymer of this embodiment in the rubber component is within the above range, the vulcanizate of the rubber composition tends to have even better wear resistance and low hysteresis loss.

[0241] To further improve its processability, the rubber composition of this embodiment may contain a rubber softener in addition to the rubber component. The rubber softener may be the same as those exemplified as those contained in the modified conjugated diene-based polymer described above, but mineral oil or a liquid or low-molecular-weight synthetic softener is preferred. Mineral oil-based rubber softeners, known as process oils or extender oils, are used to soften the rubber component, increase its volume, and improve its processability. They are mixtures of aromatic rings, naphthenic rings, and paraffin chains. Among these, those in which 50% or more of the total carbon atoms belong to paraffin chains are called paraffinic; those in which 30% to 45% of the total carbon atoms belong to naphthenic rings are called naphthenic; and those in which more than 30% of the total carbon atoms belong to aromatic carbons are called aromatic. The rubber composition using the modified conjugated diene-based polymer of this embodiment preferably contains a rubber softener with an appropriate aromatic content. The inclusion of such a rubber softener further improves compatibility with the modified conjugated diene-based polymer. The content of the rubber softener in the rubber composition using the modified conjugated diene polymer of this embodiment is represented by the total amount of the rubber softener added in advance to the modified conjugated diene polymer or the rubbery polymer and the rubber softener added when preparing the rubber composition. In the rubber composition using the modified conjugated diene polymer of this embodiment, the content of the rubber softener is preferably 0 to 100 parts by mass, more preferably 10 to 90 parts by mass, and even more preferably 30 to 90 parts by mass, per 100 parts by mass of the rubber component. By having the content of the rubber softener be 100 parts by mass or less per 100 parts by mass of the rubber component, bleed-out can be suppressed, and stickiness of the surface of the rubber composition can be further suppressed.

[0242] The rubber composition can be produced by mixing a modified conjugated diene polymer, a rubbery polymer, a filler, a silane coupling agent, a rubber softener, and the like. The mixing method is not particularly limited, but examples include melt-kneading methods using a general mixer such as an open roll, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method in which the components are dissolved and mixed and then the solvent is removed by heating. Among these, melt-kneading methods using a roll, a Banbury mixer, a kneader, or an extruder are preferred from the viewpoints of productivity and good kneading ability. The rubber component, the filler, the silane coupling agent, and the additives may be kneaded all at once, or may be mixed in multiple batches.

[0243] The rubber composition using the modified conjugated diene polymer of this embodiment may be vulcanized with a vulcanizing agent to form a vulcanizate. The vulcanizing agent is not particularly limited, but examples thereof include radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds. Examples of sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and polymeric polysulfur compounds.

[0244] In the rubber composition using the modified conjugated diene polymer of this embodiment, the content of the vulcanizing agent is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the rubber component. A conventionally known method can be used as the vulcanization method. The vulcanization temperature is preferably 120°C or more and 200°C or less, and more preferably 140°C or more and 180°C or less.

[0245] When vulcanizing the rubber composition, a vulcanization accelerator and / or vulcanization aid may be used as necessary. As the vulcanization accelerator, conventionally known materials can 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. Furthermore, examples of the vulcanization aid include, but are not limited to, zinc oxide and stearic acid. The content of each of the vulcanization accelerator and vulcanization aid is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the rubber component.

[0246] The rubber composition using the modified conjugated diene polymer of this embodiment may contain various additives such as softeners other than those described above, other fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants, as long as the effects of this embodiment are not impaired. Known softeners can be used as the softener. Examples of other fillers include, but are not limited to, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. Known materials can be used as the heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants.

[0247] The rubber composition using the modified conjugated diene polymer of this embodiment is preferably used as a rubber composition for tires. The rubber composition of this embodiment is not particularly limited, but can be preferably used for various tire parts such as fuel-efficient tires, all-season tires, high-performance tires, and studless tires, including treads, carcasses, sidewalls, and bead portions.

[0248] In addition, the numerical ranges described above as preferred ranges, etc., may be replaced with numerical ranges that arbitrarily combine the values ​​described as upper limits and the values ​​described as lower limits, unless otherwise specified.

[0249] Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples in any way.

[0250] Various physical properties in the examples and comparative examples were measured by the methods shown below.

[0251] ((Property 1) Conversion Rate) (Solid Amount) The solid amount in the modified conjugated diene polymer solution was determined from the amount of nonvolatile components in the modified conjugated diene polymer solution flowing through the measurement point per unit time. The entire amount of the modified conjugated diene polymer solution flowing through the measurement point was collected for 3 minutes, and a polymerization terminator was immediately added. The solution was then transferred to a heat-resistant dish and dried in an oven at 140°C for 30 minutes or more, after which the mass (M) of the remaining solid matter was measured. The solid amount (m) was determined using the following mathematical formula (I).

[0252]

[0253] The measurement points were the discharge part of the polymerization step (P1) for synthesizing the first polymer segment and the discharge part of the polymerization step (P2) for forming the second polymer segment, and the solid amount at each point was measured by m １ , m ２ The conversion rate c of the conjugated diene compound in the polymerization step (P1) for synthesizing the first polymer segment was bd , and the conversion rate of the aromatic vinyl compound c st were calculated using the following formulas (II) and (III), respectively. In this example, U1 is the mass of 1,3-butadiene added at the first unit per unit time, and V1 is the mass of styrene added at the first unit per unit time. In the formulas below, X １ represents the amount of bound styrene in the first polymer segment. ２ indicates the amount of bound styrene in the second polymer segment.

[0254]

[0255] The conversion rate c in the polymerization step (P1) for synthesizing the first polymer segment was calculated by the following mathematical formula (IV): In this example, U1 is the mass of 1,3-butadiene added at the first unit per unit time, and V1 is the mass of styrene added at the first unit per unit time.

[0256]

[0257] (Physical Property 2) Polymer Segment Ratio In this example, the polymer segment polymerized in the polymerization step (P1) before the monomer addition section is referred to as the first polymer segment, and the polymer segment polymerized in the subsequent polymerization step (P2) is referred to as the second polymer segment.

[0258] (The mass ratio r of the first polymer segment to the second polymer segment １ , r ２ The mass ratio r of each of the first polymer segment and the second polymer segment is expressed by the following formula (V) and formula (VI), which are the ratio of the solid mass m of each of the discharge portions of the polymerization step (P1) for synthesizing the first polymer segment and the polymerization step (P2) for forming the second polymer segment 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 throughout the entire polymerization step. １ , m ２ In this example, U is the total amount of 1,3-butadiene added in the first unit and 1,3-butadiene added in the second unit per unit time, and V is the total amount of styrene added in the first unit and styrene added in the second unit per unit time.

[0259]

[0260] (Ratio R of Mass Ratio of Polymer Segments) Ratio R of Mass Ratio of Polymer Segments (= r １ / r ２ ) was calculated using the following formula (VII).

[0261]

[0262] ((Property 3) Amount of bound aromatic vinyl monomer units (amount of bound styrene)) (amount of bound styrene in conjugated diene polymer X ａｌｌA conjugated diene polymer not containing a rubber softener was collected from the discharge port of the polymerization step (P2) for forming a second polymer segment, and 100 mg of the sample was diluted to 100 mL with chloroform and dissolved to prepare a measurement sample. The amount of bound styrene (mass%) relative to 100 mass% of the coupled conjugated diene polymer sample was measured based on the amount of absorption of ultraviolet light by the phenyl group of styrene (near 254 nm) (measuring device: Shimadzu Corporation's spectrophotometer "UV-2450").

[0263] (Amount of bound styrene in the first polymer segment X １ The sample was changed from the conjugated diene polymer to the solid content of the polymer solution discharged from the polymerization step (P1) for synthesizing the first polymer segment. The bound styrene amount was calculated in the same manner as for the bound styrene amount in the conjugated diene polymer segment, with the other conditions being the same.

[0264] (Amount of bound styrene in the second polymer segment X ２ The polymer segment ratio r in each of the polymerization step (P1) for synthesizing the first polymer segment and the polymerization step (P2) for forming the second polymer segment １ , r ２ , bound styrene amount X １ , X ａｌｌ From the above, the amount of bound styrene in the segment of the second polymer (X ２ ) was calculated.

[0265]

[0266] (Difference in the amount of bound styrene between the first polymer segment and the second polymer segment |X ２― X １ |) In order to evaluate the randomness of styrene, the difference in the amount of bound styrene between the first polymer segment and the second polymer segment is |X ２― X １ | was calculated.

[0267] ((Property 4) Amount of vinyl bonds in bound conjugated diene (amount of 1,2-vinyl bonds in bound butadiene)) (Amount of vinyl bonds in conjugated diene polymer Y ａｌｌA conjugated diene polymer not containing a rubber softener was collected from the discharge port of the polymerization step (P2) for forming the second polymer segment, and 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. The infrared spectrum of each sample was measured from 600 to 1000 cm －１ The absorbance at a predetermined wave number was measured using a Fourier transform infrared spectrophotometer (trade name "FT-IR230" manufactured by JASCO Corporation). The amount of 1,2-vinyl bonds (mol %) in the bound butadiene was determined from the absorbance at a predetermined wave number according to the Hampton method (described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)).

[0268] (Amount of vinyl bond in the first polymer segment Y １ The sample was changed from the conjugated diene polymer to the solid content of the polymer solution discharged from the polymerization step (P1) for synthesizing the first polymer segment. Regarding other conditions, the vinyl bond content was calculated in the same manner as for the vinyl bond content of the conjugated diene polymer.

[0269] (Amount of vinyl bond in the second polymer segment Y ２ In each of the polymerization step (P1) for synthesizing the first polymer segment and the polymerization step (P2) for forming the second polymer segment, the solid amount m １ , m ２ , the amount of vinyl bonds in the bonded conjugated diene Y １ , Y ａｌｌ From this, the amount of vinyl bonds in the second polymer segment was calculated using the following mathematical formula (IX).

[0270]

[0271]

[0272] (Physical Property 5) Estimated Glass Transition Temperature, Difference in Estimated Glass Transition Temperature The estimated glass transition temperatures (estimated Tg １ , estimated Tg ２ , estimated Tg) were calculated using formula (iii). １ , estimated Tg ２ When calculating the microstructure X ａｌｌ, Y ａｌｌ Each of these is X １ , Y １ and X ２ , Y ２ Just replace it with.

[0273]

[0274] The difference in estimated glass transition temperature was calculated using the following formula (XI).

[0275]

[0276] (Physical Property 6) Molecular Weight The modified conjugated diene polymers of the Examples and Comparative Examples were used as samples. A GPC measurement device (manufactured by Tosoh Corporation under the trade name "HLC-8320GPC") was used, in which three columns packed with polystyrene gel were connected. Chromatograms were measured using an RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020"). Based on a calibration curve obtained using standard polystyrene, the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were determined. The eluent used was tetrahydrofuran (THF) containing 5 mmol / L triethylamine. Three columns (manufactured by Tosoh Corporation under the trade name "TSKgel SuperMultiporeHZ-H") were connected, and a guard column (manufactured by Tosoh Corporation under the trade name "TSKguardcolumn SuperMP(HZ)-H") was connected in front of the columns. 10 mg of the sample to be measured was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL / min.

[0277] (Physical Property 7) Modification Rate The modification rate in the modified conjugated diene polymers of the examples and comparative examples was measured by column adsorption GPC method as follows. Using the modified conjugated diene polymer as a sample, the property that the modified basic polymer component is adsorbed was applied to a GPC column filled with a silica-based gel for measurement. The adsorption amount onto the silica-based column was measured from the difference between the chromatogram measured with a polystyrene-based column and the chromatogram measured with a silica-based column for a sample solution containing the sample and a low molecular weight internal standard polystyrene, and the modification rate was determined. <Preparation of Sample Solution>: 10 mg of the sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF (tetrahydrofuran) to obtain a sample solution. <GPC Measurement Conditions Using Polystyrene-Based Column>: Using the product name "HLC-8320GPC" manufactured by Tosoh Corporation, THF containing 5 mmol / L of triethylamine was used as an eluent, 10 μL of the sample solution was injected into the apparatus, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40 °C and a THF flow rate of 0.35 mL / min. For the column, three columns with the product name "TSKgel SuperMultiporeHZ-H" manufactured by Tosoh Corporation were connected in series, and a guard column with the product name "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation was connected in front of them for use. <GPC Measurement Conditions Using Silica-Based Column> GPC measurement was performed using the product name "HLC-8320GPC" manufactured by Tosoh Corporation and an RI detector (product name "HLC8020" manufactured by Tosoh Corporation). Using THF as an 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. For the column, columns with the product names "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S" manufactured by Agilent Technologies were connected in this order, and a guard column with the product name "DIOL 4.6×12.5 mm 5 micron" was connected in front of them for use.<Method of calculating modification rate>: The total peak area of ​​the chromatogram using a polystyrene-based column was set to 100, the peak area of ​​the sample was set to p1, the peak area of ​​the standard polystyrene was set to p2, the total peak area of ​​the chromatogram using a silica-based column was set to 100, the peak area of ​​the sample was set to p3, and the peak area of ​​the standard polystyrene was set to p4, and the modification rate (%) was calculated using the following formula: Modification rate (%) = [1 - (p2 × p3) / (p1 × p4)] × 100 (where p1 + p2 = p3 + p4 = 100).

[0278] (Physical Property 8) Degree of Branching (Bn) The degree of branching (Bn) of a modified conjugated diene polymer was measured by a GPC-light scattering method with a viscosity detector as follows. Using a modified conjugated diene polymer as a sample, a GPC measurement device (trade name "GPCmax VE-2001" manufactured by Malvern) in which three columns packed with polystyrene gel were connected was used, and measurement was carried out using three detectors connected in this order: a light scattering detector, an RI detector, and a viscosity detector (trade name "TDA305" manufactured by Malvern). Based on standard polystyrene, the absolute molecular weight was determined from the results of the light scattering detector and the RI detector, and the intrinsic viscosity was determined from the results of the RI detector and the viscosity detector. A linear polymer had an intrinsic viscosity [η ０ ]=10 －３．４９８ M ０．７１１ The shrinkage factor (g') was calculated as the ratio of intrinsic viscosity corresponding to each molecular weight according to the following formula. In this formula, M is the absolute molecular weight. THF containing 5 mmol / L triethylamine was used as the eluent. Columns manufactured by Tosoh Corporation under the trade names "TSKgel G4000HXL," "TSKgel G5000HXL," and "TSKgel G6000HXL" were used. 20 mg of the sample to be measured was dissolved in 10 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40°C and a THF flow rate of 1 mL / min. From the measurement, the absolute molecular weight distribution curve and branching degree distribution curve of the modified conjugated diene polymer were obtained, and the branching degree (Bn), defined as g' = 6Bn / {(Bn + 1)(Bn + 2)}, was calculated using the shrinkage factor (g').

[0279] (Physical Property 9) tan δ Peak Height The tan δ peak height was measured by dynamic viscoelastic analysis using an ARES (Advanced Rheometric Expansion System) as follows. 3 g of a modified conjugated diene polymer was dissolved in 30 mL of tetrahydrofuran, and then methanol was added to the resulting solution to precipitate the polymer. The resulting polymer was completely dried using a vacuum dryer at 40 ° C. The dried polymer was pressed at 120 ° C. for 3 minutes to form a 1 mm thick sheet, which was then punched out into a 10 mm diameter circle to prepare a measurement sample. Using a dynamic mechanical analyzer (TA Corporation, ARES-G2), tan δ was measured in torsional mode at a frequency of 10 Hz, a strain rate of 0.5%, and a heating rate of 5 ° C. / min over a temperature range of -100 ° C. to 100 ° C. The results were plotted with the horizontal axis representing temperature and the vertical axis representing tan δ, and the value of tan δ at the maximum point was taken as the height of the tan δ peak.

[0280] (Physical Property 10) Polymer Mooney Viscosity The modified conjugated diene polymers of the 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. First, the sample was preheated at the test temperature for 1 minute, and then the rotor was rotated at 2 rpm. After 4 minutes, the torque was measured to determine the Mooney viscosity (ML （１＋４） )

[0281] [Production of Modified Conjugated Diene Polymer] (Example 1) Two tank-type pressure vessels each having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom, an outlet at the top, and a jacket for temperature control, were connected as polymerization reactors. 1,3-butadiene, from which moisture had been removed in advance, was mixed at 17.4 g / min, styrene at 5.8 g / min, and normal hexane at 180.1 g / min to obtain a mixed solution. n-Butyllithium for inactivating residual impurities was added at 0.104 mmol / min in a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reactor, and after mixing, the mixture was continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.034 mmol / min and n-butyllithium as a polymerization initiator at a rate of 0.203 mmol / min were supplied to the bottom of the first reactor, which was being vigorously mixed with a stirrer, and the temperature inside the reactor was maintained at 82°C. When the polymerization reaction became stable, a small amount of conjugated diene polymer was withdrawn from the top of the reactor, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer. Thereafter, the solvent was removed, and the amount of bound aromatic vinyl in the first polymer segment (X １ ) and the amount of vinyl bonds in the bonded conjugated diene (Y １ ), and conversion rate c, styrene conversion rate c st was measured.

[0282] Next, while continuously supplying the polymer solution from the top of the first reactor to the bottom of the second reactor, 1,3-butadiene, styrene, and normal hexane were added to the connecting piping (corresponding to the monomer addition section) at rates of 7.5 g / min, 2.6 g / min, 42.9 g / min, 2,2-bis(2-oxolanyl)propane as a polar substance, and 0.062 mmol / min, and trimethoxy(4-vinylphenyl)silane as a branching agent, at rates of 0.025 mmol / min, with stirring, and the reaction was continued at 85°C.

[0283] Next, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (coupling modifier A in the table) was continuously added as a coupling modifier to the polymer solution flowing out from the top of the second reactor at a rate of 0.028 mmol / min, and the mixture was mixed using a static mixer to carry out a coupling reaction.

[0284] Next, an antioxidant (BHT) was continuously added to the polymer solution after the coupling reaction at a rate of 0.055 g / min (n-hexane solution) so that the amount was 0.2 g per 100 g of polymer, and the coupling reaction was terminated. Thereafter, 25 phr of S-RAE oil (trade name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation) was added as a plasticizer, and the mixture was mixed with a stirrer. The solvent was removed by steam stripping to obtain a modified conjugated diene-based polymer (A1), which was then used to measure various physical properties.

[0285] Example 2 A modified conjugated diene polymer of Example 2 was obtained in the same manner as in Example 1, except that the 1,3-butadiene, styrene, and normal hexane were supplied to the first reactor at rates of 16.7 g / min, 5.3 g / min, and 176.2 g / min, and the 1,3-butadiene, styrene, and normal hexane were added to the second reactor at rates of 9.8 g / min, 1.5 g / min, 46.9 g / min, and 0.255 mmol / min of the polar substance, and the polymerization temperature of the second reactor was changed to 78°C and the coupling modification addition amount to 0.018 mmol / min.

[0286] Example 3 A modified conjugated diene polymer of Example 3 was obtained in the same manner as in Example 2, except that the amount of the coupling modifier added was changed to 0.028 mmol / min.

[0287] Example 4 A modified conjugated diene polymer of Example 4 was obtained in the same manner as in Example 1, except that the rates of 1,3-butadiene and styrene supplied to the first reactor were changed to 17.2 g / min and 5.4 g / min, respectively, and the rates of 1,3-butadiene, styrene, normal hexane, and polar substance added to the second reactor were changed to 7.4 g / min, 3.3 g / min, 43.0 g / min, and 0.119 mmol / min, respectively.

[0288] Example 5 A modified conjugated diene polymer of Example 5 was obtained in the same manner as in Example 4, except that the branching agent added to the second group was changed to 0.012 mmol / min.

[0289] Example 6 A modified conjugated diene polymer of Example 6 was obtained in the same manner as in Example 4, except that the n-butyllithium as the polymerization initiator supplied to the first reactor was 0.167 mmol / min, the polar substance was 0.029 mmol / min, the polar substance added to the second reactor was 0.107 mmol / min, no branching agent was added, and the coupling modifier was changed to 0.023 mmol / min.

[0290] Example 7 A modified conjugated diene polymer of Example 7 was obtained in the same manner as in Example 4, except that the rates of n-butyllithium as a polymerization initiator supplied to the first reactor were changed to 0.229 mmol / min, the polar substance to 0.040 mmol / min, and the polar substance, branching agent, and coupling modifier to 0.137 mmol / min, 0.036 mmol / min, and 0.027 mmol / min, respectively.

[0291] Example 8 A modified conjugated diene polymer of Example 8 was obtained in the same manner as in Example 4, except that the rates of n-butyllithium as a polymerization initiator supplied to the first reactor were changed to 0.177 mmol / min, the polar substance to 0.031 mmol / min, and the polar substance, branching agent, and coupling modifier to 0.105 mmol / min, 0.023 mmol / min, and 0.025 mmol / min, respectively.

[0292] Example 9 A modified conjugated diene polymer of Example 9 was obtained in the same manner as in Example 4, except that the rates of n-butyllithium as a polymerization initiator supplied to the first reactor were changed to 0.167 mmol / min, the polar substance to 0.029 mmol / min, and the polar substance, branching agent, and coupling modifier to 0.101 mmol / min, 0.022 mmol / min, and 0.023 mmol / min, respectively.

[0293] (Example 10) A modified conjugated diene polymer of Example 10 was obtained in the same manner as in Example 4, except that the branching agent added to the second group was changed to 0.033 mmol / min and the coupling modifier was changed to 0.024 mmol / min.

[0294] Example 11 A modified conjugated diene polymer of Example 11 was obtained in the same manner as in Example 1, except that the rates of 1,3-butadiene, styrene, and normal hexane supplied to the first reactor were changed to 18.8 g / min, 3.6 g / min, and 177.7 g / min, and the rates of 1,3-butadiene, styrene, normal hexane, and polar substance added to the second reactor were changed to 10.1 g / min, 0.9 g / min, 45.4 g / min, and 0.255 mmol / min.

[0295] Example 12 A modified conjugated diene polymer of Example 12 was obtained in the same manner as in Example 1, except that the rates of 1,3-butadiene, styrene, and polar substance supplied to the first reactor were changed to 17.4 g / min, 4.6 g / min, and 0.090 mmol / min, respectively, and the rates of styrene and polar substance added to the second reactor were changed to 3.8 g / min and 0.081 mmol / min.

[0296] Example 13 A modified conjugated diene polymer of Example 13 was obtained in the same manner as in Example 1, except that the 1,3-butadiene, styrene, normal hexane, and polar substance supplied to the first reactor were changed to 14.1 g / min, 4.7 g / min, 174.3 g / min, and 0.118 mmol / min, respectively, and the polymerization temperature of the second reactor was changed to 78°C. The 1,3-butadiene, styrene, normal hexane, and polar substance supplied to the second reactor were changed to 9.4 g / min, 5.1 g / min, 48.7 g / min, and 0.172 mmol / min, respectively, and the polymerization temperature of the second reactor was changed to 78°C.

[0297] Example 14 A modified conjugated diene polymer of Example 14 was obtained in the same manner as in Example 1, except that the rates of 1,3-butadiene, styrene, and normal hexane to be supplied to the first reactor were changed to 17.7 g / min, 6.5 g / min, and 180.2 g / min, and the rates of 1,3-butadiene, styrene, normal hexane, and polar substance to be added to the second reactor were changed to 7.6 g / min, 1.6 g / min, 42.8 g / min, and 0.128 mmol / min.

[0298] Example 15 A modified conjugated diene polymer of Example 15 was obtained in the same manner as in Example 1, except that the rates of 1,3-butadiene, styrene, and normal hexane to be supplied to the first reactor were changed to 17.4 g / min, 5.8 g / min, and 180.1 g / min, and the rates of 1,3-butadiene, styrene, normal hexane, and polar substance to be added to the second reactor were changed to 7.5 g / min, 2.6 g / min, 42.9 g / min, and 0.121 mmol / min.

[0299] Example 16 A modified conjugated diene polymer of Example 16 was obtained in the same manner as in Example 5, except that no plasticizer was added.

[0300] Example 17 A modified conjugated diene polymer of Example 17 was obtained in the same manner as in Example 3, except that the rates of 1,3-butadiene, styrene, and normal hexane supplied to the first reactor were changed to 15.6 g / min, 4.7 g / min, and 173.1 g / min, and the rates of 1,3-butadiene, styrene, normal hexane, and polar substance added to the second reactor were changed to 11.3 g / min, 1.8 g / min, 50.0 g / min, and 0.121 mmol / min.

[0301] Comparative Example 1 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, styrene, normal hexane, and polar substance supplied to the first reactor were 17.8 g / min, 8.0 g / min, 180.3 g / min, and 0.045 mmol / min, respectively, and the reaction temperature of the first polymerization reactor was 65°C. Styrene and the polar substance were not added to the second reactor, and the 1,3-butadiene, normal hexane, and polar substance were added to the second reactor at 7.6 g / min and 42.8 g / min, respectively, and the reaction temperature of the second polymerization reactor was changed to 90°C.

[0302] Comparative Example 2 A modified conjugated diene-based polymer of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the rates of 1,3-butadiene, styrene, normal hexane, and polar substance supplied to the first reactor were changed to 20.0 g / min, 6.7 g / min, 183.7 g / min, and 0.033 mmol / min, respectively, and the reaction temperature of the first polymerization reactor was changed to 70°C, and the rates of 1,3-butadiene, normal hexane, and 39.4 g / min added to the second reactor were changed to 6.7 g / min, 39.4 g / min, and the reaction temperature of the second polymerization reactor was changed to 90°C.

[0303] Comparative Example 3 A modified conjugated diene polymer of Comparative Example 3 was obtained in the same manner as in Comparative Example 1, except that the n-butyllithium as a polymerization initiator supplied to the first reactor was 0.104 mmol / min, the polar substance was 0.025 mmol / min, and no branching agent was added to the second reactor, and the coupling modifier was changed to 0.016 mmol / min.

[0304] Comparative Example 4 A modified conjugated diene polymer of Comparative Example 4 was obtained in the same manner as in Comparative Example 1, except that the amount of coupling modifier added was changed to 0.047 mmol / min.

[0305] Comparative Example 5 A modified conjugated diene polymer of Comparative Example 5 was obtained in the same manner as in Comparative Example 1, except that the polymerization initiators supplied to the first reactor were n-butyllithium at 0.250 mmol / min, 1,3-butadiene at 19.8 g / min, styrene at 5.1 g / min, normal hexane at 146.7 g / min, and polar substance at 0.008 mmol / min, and the reaction temperature of the first polymerization reactor was 60°C, the polymerization initiators added to the second reactor were 1,3-butadiene at 8.5 g / min, normal hexane at 42.1 g / min, and polar substance at 0.109 mmol / min, no branching agent was added, the reaction temperature of the second polymerization reactor was 60°C, and N,N-dimethyl-3-(trimethoxysilyl)propan-1-amine (coupling modifier B in the table) was used instead of A as the coupling modifier at 0.047 mmol / min, and no plasticizer was added.

[0306] Comparative Example 6 A modified conjugated diene polymer of Comparative Example 6 was obtained in the same manner as in Comparative Example 4, except that the polar substance supplied to the first reactor was changed to 0.007 mmol / min, the reaction temperature of the first polymerization reactor was changed to 60°C, and the 1,3-butadiene added to the second reactor was changed to 8.5 g / min, the branching agent to 0.025 mmol / min, the polarizable substance to 0.091 mmol / min, and the coupling modifier A to 0.028 mmol / min.

[0307] Comparative Example 7 A modified conjugated diene-based polymer of Comparative Example 7 was obtained in the same manner as in Comparative Example 6, except that the polar substance supplied to the first reactor was changed to 0.016 mmol / min, the reaction temperature of the first polymerization reactor was changed to 65°C, the polar substance added to the second reactor was changed to 0.257 mmol / min, and the reaction temperature of the second polymerization reactor was changed to 85°C.

[0308] Comparative Example 8 A modified conjugated diene polymer of Comparative Example 8 was obtained in the same manner as in Comparative Example 1, except that the polymerization initiators supplied to the first reactor were n-butyllithium at 0.250 mmol / min, 1,3-butadiene at 18.4 g / min, styrene at 5.8 g / min, normal hexane at 146.3 g / min, and polar substance at 0.011 mmol / min, and the reaction temperature of the first polymerization reactor was 60°C, the polymerization initiators added to the second reactor were 10.2 g / min, normal hexane at 50.6 g / min, and polar substance at 0.109 mmol / min, no branching agent was added, the reaction temperature of the second polymerization reactor was 60°C, and bis(3-(diethoxymethylsilylpropyl)-N-methylamine (coupling modifier C in the Table) was used at 0.053 mmol / min instead of A as the coupling modifier, and no plasticizer was added.

[0309] Comparative Example 9 Batch polymerization was carried out using a 20 L tank-type polymerization reactor equipped with a stirrer according to the following procedure. 7.65 kg of hexane, 2.93 kg of cyclohexane, 240 g of 1,3-butadiene, 510 g of styrene, 8.8 mL of tetrahydrofuran, and 0.9 mL of ethylene glycol dibutyl ether were charged into the polymerization reactor, the internal atmosphere of which had been replaced with dry nitrogen. Next, a small amount of a hexane solution of n-butyllithium was charged as a scavenger into the polymerization reactor to detoxify impurities that may deactivate the polymerization initiator. An n-hexane solution containing 3.12 mmol of n-BuLi was then charged into the polymerization reactor to initiate the polymerization reaction. The polymerization reaction was carried out for 4 hours and 10 minutes. During the polymerization reaction, the temperature inside the polymerization reactor was adjusted to 65°C, and the solution inside the polymerization reactor was stirred at a stirring speed of 100 rpm. 660 g of 1,3-butadiene and 90 g of styrene were continuously fed into the polymerization reactor over a period of 3 hours and 20 minutes starting 20 minutes after the start of polymerization. Next, while maintaining the polymerization reactor temperature at 65°C, the resulting polymerization solution was stirred in the polymerization reactor at a stirring speed of 100 rpm, and 0.25 mmol of silicon tetrachloride was added to the polymerization solution, followed by stirring for 15 minutes. Next, 5 mL of a hexane solution containing 0.8 mL of methanol was added to the polymerization reactor, and the polymerization solution was stirred for 5 minutes. Thereafter, 0.3 parts by mass of an antioxidant (BHT) was added as a stabilizer per 100 parts by mass of the polymer, to obtain a conjugated diene-based polymer of Comparative Example 9.

[0310]

[0311]

[0312]

[0313]

[0314] [Examples 18 to 34], [Comparative Examples 10 to 18] Using the modified conjugated diene polymers of the Examples and Comparative Examples shown in Tables 1 to 4 as raw rubbers, rubber compositions containing the respective raw rubbers were obtained according to the formulations shown below. Modified conjugated diene polymers (Examples 1 to 17, Comparative Examples 1 to 9): 100 parts by mass (oil excluded) Silica (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa, nitrogen adsorption specific surface area 170 m2 / g): 85.0 parts by mass Carbon black (trade name "SEAST 7HM (N234)" manufactured by Tokai Carbon Co., Ltd.): 2.0 parts by mass Silane coupling agent (trade name "Si69" manufactured by Evonik Degussa, bis(triethoxysilylpropyl)tetrasulfide): 6.8 parts by mass S-RAE oil (trade name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation): 40 parts by mass Zinc oxide: 2.4 parts by mass Stearic acid: 1.25 parts by mass Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 3.5 parts by mass Sulfur: 1.0 part by mass Vulcanization accelerator 1 Tetrabenzyl thiuram disulfide: 0.5 parts by mass Vulcanization accelerator 2 N-(tert-butyl)-2-benzothiazole sulfenamide: 2.5 parts by mass Total: 246.95 parts by mass

[0315] The above materials were kneaded by the following method to obtain rubber compositions. Using an internal kneader (capacity: 0.3 L) equipped with a temperature control device, the raw rubber, filler (silica, carbon black), silane coupling agent, process oil, zinc oxide, and stearic acid were kneaded in the first stage at a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm. The temperature of the internal mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 145 to 150°C.

[0316] Next, in the second stage of mixing, the compound obtained above was cooled to room temperature, and then an antioxidant was added and mixed again to improve the dispersion of silica. In this case, the discharge temperature of the compound was adjusted to 120°C by temperature control of the mixer. After cooling, in the third stage of mixing, sulfur and vulcanization accelerators 1 and 2 were added and mixed using an open roll set at 70°C. The mixture was then molded and vulcanized in a vulcanization press at 160°C for 20 minutes. The rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, the evaluation was performed using the following methods.

[0317] [Evaluation 1 and Evaluation 2: Viscoelastic Parameters] Viscoelastic parameters were measured in torsion mode using an "ARES" viscoelasticity tester manufactured by Rheometrics Scientific Inc. Each measurement value was indexed, with the result for the rubber composition of Comparative Example 10 being set at 100.

[0318] (Evaluation 1: Fuel Saving Performance) Tan δ measured at 50°C, a frequency of 10 Hz, and a strain of 1% was used as an index of fuel saving performance. A larger index value indicates better fuel saving performance. An index value of 85 or more was determined to have good fuel saving performance as a vulcanizate.

[0319] (Evaluation 2: Wet Grip Performance) Tan δ measured at 0°C, a frequency of 10 Hz, and a strain of 1% was used as an index of wet grip performance. A larger index value indicates better wet grip performance. An index value of 90 or more was determined to have good fuel-saving performance as a vulcanizate.

[0320] [Evaluation 3: Abrasion Resistance] Using an Acron abrasion tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the amount of abrasion was measured at a load of 44.4 N and 1,000 revolutions in accordance with JIS K6264-2, and the result of Comparative Example 10 was indexed as 100. A larger index indicates better abrasion resistance.

[0321] [Evaluation 4: Tensile Properties] Tensile strength and tensile elongation were measured in accordance with the tensile testing method of JIS K6251, and the product of these values ​​was indexed, with the result of Comparative Example 10 being set at 100. A larger index indicates better tensile strength and tensile elongation (breaking strength). An index value of 85 or more was determined to have sufficient tensile properties as a vulcanizate.

[0322] [Evaluation 5: Processability] The unvulcanized modified conjugated diene polymers produced by the methods shown in the Examples and Comparative Examples were visually observed for cohesion (shape) immediately after being discharged from the pressure kneader (immediately after the first stage of kneading in the pressure kneader was completed and the polymer was discharged), and evaluated based on the following criteria, with 5 points being the maximum score per panelist. Cohesion is an index of the processability of the vulcanized product. A higher index indicates better processability. <Evaluation Criteria> 1: The edge portions of the sheet are 50% or less smooth, resulting in very poor processability. 2: The edge portions of the sheet are more than 50% but not more than 60% smooth, resulting in poor processability. 3: The edge portions of the sheet are more than 60% but not more than 80% smooth, resulting in good processability. 4: The edge portions of the sheet are more than 80% but not more than 90% smooth, resulting in excellent processability. 5: The edge portions of the sheet are more than 90% smooth, resulting in excellent processability.

[0323] It was confirmed that, compared with Comparative Examples 10 to 18, Examples 18 to 34 exhibited excellent balance of fuel economy performance, wet grip performance, abrasion resistance and tensile properties when vulcanized.

[0324]

[0325]

[0326]

[0327]

[0328] This application is based on a Japanese patent application (Patent Application No. 2024-003559) filed with the Japan Patent Office on January 12, 2024, the contents of which are incorporated herein by reference.

[0329] The modified conjugated diene polymer of the present invention has industrial applicability as a material in fields such as tire treads, interior and exterior parts of automobiles, vibration-proof rubber, belts, footwear, foams, and various industrial goods.

Claims

1. A modified conjugated diene-based polymer comprising a conjugated diene monomer unit and an aromatic vinyl monomer unit, having a weight average molecular weight of 700,000 or more as measured by GPC, a modification rate of 60% or more, and in a tanδ peak graph according to temperature derived from dynamic viscoelasticity analysis based on the following <Condition 1> by ARES (Advanced Rheometric Expansion System), having 1 tanδ peak in the temperature range of -100°C to 100°C, and the height of the tanδ peak being 0.90 or more and 1.45 or less. <Condition 1> Using a dynamic mechanical analyzer, in torsional mode, measure under the conditions of a frequency of 10 Hz, a strain of 0.5%, and a heating rate of 5°C / min to obtain a tanδ peak graph.

2. The modified conjugated diene-based polymer according to claim 1, having a branching degree (Bn) of 7 or more as measured by GPC - light scattering method with a viscosity detector.

3. The modified conjugated diene-based polymer according to claim 1, having a molecular weight distribution of 1.7 or more and 2.5 or less.

4. The modified conjugated diene-based polymer according to claim 1, having an estimated glass transition temperature (estimated Tg) derived from the microstructure in the modified conjugated diene-based polymer of -62°C or more and less than -25°C.

5. Having two or more polymer segments, the mass fraction in the modified conjugated diene-based polymer being 10% or more, the estimated glass transition temperature (estimated Tg) of the first polymer segment, which is the polymer segment closest to the start end, being -90°C or more and -40°C or less, the estimated Tg of the second polymer segment, which is the polymer segment closest to the end end, being -50°C or more and -10°C or less and being not less than the estimated Tg of the first polymer segment, and the modifier being bonded to the end of the second polymer segment. The modified conjugated diene-based polymer according to claim 1.

6. The modified conjugated diene-based polymer according to claim 1, having a modifier residue derived from an alkoxysilane compound having a nitrogen atom.

7. A method for producing a conjugated diene polymer according to any one of claims 1 to 6, which uses a continuous reactor in which two or more reactors are connected in series, has a polymerization step of polymerizing at least one conjugated diene compound using a lithium compound as a polymerization initiator, the continuous reactor has a monomer addition section for adding at least one conjugated diene compound and an aromatic vinyl compound during the polymerization step, and has a coupling step of reacting the conjugated diene polymer obtained by the polymerization step with a modifier having a nitrogen atom. A method for producing a modified conjugated diene polymer.

8. In the polymerization step, an aromatic vinyl compound is used as a polymerization monomer, and the conversion rate of the aromatic vinyl compound in the polymerization intermediate in the monomer addition section is 70% or more. The method for producing a modified conjugated diene polymer according to claim 7.

9. The method for producing a modified conjugated diene polymer according to claim 7, wherein the position of the monomer addition section is between the pipes of the first and second reactors of the continuous reactor.

10. A branching agent is added in the monomer addition section. The method for producing a modified conjugated diene polymer according to claim 7.

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