Modified conjugate diene-based polymers and their manufacturing methods; rubber components and rubber tires.

Abstract

OCR This invention provides for a weight-modified conjugate diene-based polymer. The molecular weight average is 20 x 10⁴ or more and 300 x 10⁴ or less, which is positive. A polymer based on a modified conjugated diene with a molecular weight of 200 x 10⁴ or more. That, and 500 x 10 to the power of 4 or less, is included in a volume of 0.259 by mass or more. Furthermore, 30% by mass or less compared to the total volume of the polymer-based material. The modified conjugated diene and shrinkage factor (g'') were less than 0.64.

Description

Modified conjugated diene polymer, method for producing the same, rubber composition, and tire

[0001] The present invention relates to a modified conjugated diene-based polymer, a method for producing the same, a rubber composition, and a tire.

[0002] In recent years, increasing demands for improved fuel economy for automobiles have led to a demand for improvements in the materials used in automobile tires, particularly in the tire treads that come into contact with the ground. To date, there has been a demand for the development of materials with low rolling resistance, i.e., low hysteresis loss. Furthermore, to reduce the weight of tires, it is necessary to reduce the thickness of the tire tread, and materials with high abrasion resistance are also required. On the other hand, from the perspective of safety, materials used for tire treads are required to have excellent wet skid resistance and sufficient fracture properties for practical use.

[0003] Materials that meet these requirements include those containing rubber and reinforcing fillers such as carbon black and silica. For example, the use of a material containing silica can improve the balance between low hysteresis loss and wet skid resistance. Furthermore, attempts have been made to improve the dispersibility of silica in materials by introducing functional groups that have affinity or reactivity with silica into the molecular terminals of highly mobile rubber, and further reduce the mobility of the rubber molecular terminals by bonding with silica particles, thereby reducing hysteresis loss.

[0004] For example, Patent Document 1 proposes a modified diene rubber obtained by reacting a modifier having a glycidylamino group with an active terminal of a polymer. Patent Documents 2 to 4 propose modified diene rubbers obtained by reacting alkoxysilanes containing amino groups with an active terminal of a polymer, and compositions of these modified diene rubbers with silica. Patent Documents 5 and 6 propose polymers functionalized by reacting a cyclic azasilacycle compound with an active terminal of a polymer. Patent Document 7 also proposes a diene rubber obtained by coupling a polymer active terminal with a polyfunctional silane compound.

[0005] WO 01 / 23467 pamphlet JP 2005-290355 A JP 11-189616 A JP 2003-171418 A JP 2008-527150 A WO 11 / 129425 pamphlet WO 07 / 114203 pamphlet

[0006] However, silica-containing materials have a drawback of poor dispersibility compared to carbon black, due to their hydrophilic surface and low affinity with conjugated diene rubbers, as opposed to carbon black, which has a hydrophobic surface. Therefore, silica-containing materials require the addition of a silane coupling agent or the like to provide a bond between the silica and the rubber and improve dispersibility. Furthermore, materials with functional groups highly reactive with silica introduced at the molecular end of the rubber tend to have poor processability, such as difficulty in kneading due to the progress of reaction with silica particles during the kneading process, increasing the viscosity of the composition, or causing surface roughness or sheet breakage when kneading and forming the sheet. Furthermore, when such materials are vulcanized, especially when they contain inorganic fillers such as silica, the balance between low hysteresis loss and wet skid resistance, and abrasion resistance are insufficient.

[0007] Therefore, an object of the present invention is to provide a modified conjugated diene polymer which has excellent processability when made into a vulcanizate, and which, when made into a vulcanizate, has a balance between low hysteresis loss and wet skid resistance, excellent abrasion resistance, and fracture properties sufficient for practical use.

[0008] As a result of intensive research and investigation to solve the problems of the prior art, the present inventors have found that a modified conjugated diene-based polymer having a weight-average molecular weight within a predetermined range, containing a predetermined amount of the modified conjugated diene-based polymer having a molecular weight within the predetermined range and having a shrinkage factor (g') of less than a predetermined value, has excellent processability when vulcanized, and when vulcanized, has excellent balance between low hysteresis loss and wet skid resistance, excellent abrasion resistance, and has fracture properties sufficient for practical use, thereby completing the present invention.

[0009] That is, the present invention is as follows: [1] A polymer having a weight average molecular weight of 20×10 ４ 300 x 10 or more ４ A modified conjugated diene polymer having a molecular weight of 200×10 or less relative to the total amount of the modified conjugated diene polymer. ４ Above 500 x 10 ４ [2] The modified conjugated diene polymer according to [1], which contains 0.25% by mass or more and 30% by mass or less of the modified conjugated diene polymer having a weight average molecular weight of 50×10 or less, and has a shrinkage factor (g') of less than 0.64. [3] The modified conjugated diene polymer according to [1], which contains nitrogen atoms and silicon atoms. [4] The weight average molecular weight is 50×10 or less. ４ Above 150 x 10 ４ [4] The modified conjugated diene polymer according to [1] or [2], wherein the molecular weight is 200 × 10 or less relative to the total amount of the modified conjugated diene polymer. ４ Above 500 x 10 ４ The modified conjugated diene-based polymer according to any one of [1] to [3], comprising 1.0 mass % to 30 mass % of the modified conjugated diene-based polymer having the following structure: [5] The modified conjugated diene-based polymer according to any one of [1] to [4], which has branches and has a degree of branching of 5 or more. [6] The modified conjugated diene-based polymer according to [5], which has a degree of branching of 6 or more. [7] The modified conjugated diene-based polymer according to [5] or [6], which has one or more coupling residues and conjugated diene-based polymer chains bonded to the coupling residues, wherein the branches include branches in which five or more of the conjugated diene-based polymer chains are bonded to one coupling residue. [8] The modified conjugated diene-based polymer according to any one of [5] to [7], which includes branches in which six or more of the conjugated diene-based polymer chains are bonded to one coupling residue. [9] The modified conjugated diene polymer according to [7] or [8], wherein at least one silicon atom in the coupling residue constitutes an alkoxysilyl group or a silanol group having 1 to 20 carbon atoms.

[10] The modified conjugated diene polymer according to any one of [1] to [9], represented by the following general formula (I): (In formula (I), D １ represents a diene polymer chain, and R１ ~R ３ each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms; R ４ and R ７ each independently represents an alkyl group having 1 to 20 carbon atoms; R ５ , R ８ , and R ９ each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; R ６ and R １０ each independently represents an alkylene group having 1 to 20 carbon atoms; R １１ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. m and x each independently represent an integer of 1 to 3, with x≦m, p represents 1 or 2, y represents an integer of 1 to 3, with y≦(p+1), and z represents an integer of 1 or 2. When there are multiple D １ , R １ ~R １１ , m, p, x, y, and z are each independent and may be the same or different. i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, (i + j + k) is an integer of 3 to 10, and ((x × i) + (y × j) + (z × k)) is an integer of 5 to 30. A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of oxygen atoms, nitrogen atoms, silicon atoms, sulfur atoms, and phosphorus atoms, and having no active hydrogen atoms.)

[11] The modified conjugated diene-based polymer according to

[10] , wherein A in formula (I) is represented by any of the following general formulae (II) to (V): (In formula (II), B １ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. １ are independent of each other.) (In formula (III), B ２ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ３ represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ２ and B ３ are independent of each other.) (In formula (IV), B４ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ４ are independent of each other.) (In formula (V), B ５ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ５ are each independent.)

[12] A method for producing a modified conjugated diene polymer according to any one of [1] to

[11] , comprising: a polymerization step of polymerizing at least a conjugated diene compound using an organic monolithium compound as a polymerization initiator to obtain a conjugated diene polymer; and a reaction step of reacting the conjugated diene polymer with a compound represented by the following general formula (VI): (In formula (VI), R １２ ~R １４ each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms; R １５ ~R １８ , and R ２０ each independently represents an alkyl group having 1 to 20 carbon atoms; R １９ and R ２２ each independently represents an alkylene group having 1 to 20 carbon atoms; R ２１ represents an alkyl group or a trialkylsilyl group having 1 to 20 carbon atoms, m represents an integer of 1 to 3, and p represents 1 or 2. When a plurality of R １２ ~R ２２ , m, and p are each independent and may be the same or different. i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, and (i + j + k) is an integer of 3 to 10. A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of oxygen atoms, nitrogen atoms, silicon atoms, sulfur atoms, and phosphorus atoms, and having no active hydrogen.)

[13] The method for producing a modified conjugated diene polymer according to

[12] , wherein A in formula (VI) is represented by any of the following general formulae (II) to (V): (In formula (II), B １represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. １ are independent of each other.) (In formula (III), B ２ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ３ represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ２ and B ３ are independent of each other.) (In formula (IV), B ４ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ４ are independent of each other.) (In formula (V), B ５ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ５ are each independent.)

[14] The method for producing a modified conjugated diene polymer according to

[13] , wherein in formula (VI), A is represented by formula (II) or formula (III), and k is 0.

[15] The method for producing a modified conjugated diene polymer according to

[13] or

[14] , wherein in formula (VI), A is represented by formula (II) or formula (III), and k is 0, and in formula (II) or formula (III), a is an integer of 2 to 10.

[16] The method for producing a modified conjugated diene polymer according to any one of

[12] to

[15] , wherein the organomonolithium compound is an alkyllithium compound having a substituted amino group or a dialkylaminolithium.

[17] The method for producing a modified conjugated diene polymer according to any one of

[12] to

[15] , wherein the organomonolithium compound is an alkyllithium compound.

[18] A rubber composition comprising a rubber component and 5.0 parts by mass to 150 parts by mass of a filler per 100 parts by mass of the rubber component, wherein the rubber component contains 10% by mass or more of the modified conjugated diene-based polymer according to any one of [1] to

[11] relative to the total amount of the rubber component.

[19] A tire made using the rubber composition according to

[18] .

[0010] The modified conjugated diene-based polymer according to the present invention can provide excellent processability when vulcanized, and when vulcanized, can provide an excellent balance of low hysteresis loss and wet skid resistance, as well as abrasion resistance and practically sufficient fracture properties.

[0011] 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.

[0012] [Modified Conjugated Diene Polymer] The modified conjugated diene polymer of the present embodiment has a weight average molecular weight of 20×10 ４ 300 x 10 or more ４ and the molecular weight is 200×10 or less relative to the total amount (100% by mass) of the modified conjugated diene polymer. ４ Above 500 x 10 ４ The composition contains 0.25% by mass or more and 30% by mass or less of the modified conjugated diene-based polymer having the following characteristics, and has a shrinkage factor (g') of less than 0.64.

[0013] In general, polymers having branches tend to have smaller molecular size compared to linear polymers having the same absolute molecular weight. The shrinkage factor (g') in this embodiment is an index of the ratio of the molecular size to that of a linear polymer having the same assumed absolute molecular weight. In other words, the shrinkage factor (g') tends to decrease as the degree of branching of the polymer increases. In this embodiment, intrinsic viscosity is used as an index of molecular size, and linear polymers have an intrinsic viscosity [η] = -3.883 M ０．７７１ The shrinkage factor (g') is calculated for each absolute molecular weight of the modified conjugated diene polymer, and the shrinkage factor (g') is calculated for the absolute molecular weight of 100 x 10 ４ ~200 x 10 ４The average value of the contraction factor (g') when the above formula is used is the contraction factor (g') of the modified conjugated diene polymer. Here, "branch" refers to a branch formed by direct or indirect bonding of one polymer to another polymer. Furthermore, the "degree of branching" refers to the number of polymers that are directly or indirectly bonded to one branch. For example, when five conjugated diene polymer chains (described below) are indirectly bonded to one another via a coupling agent residue (described below), the degree of branching is 5.

[0014] The shrinkage factor (g') is less than 0.64, preferably 0.63 or less, more preferably 0.60 or less, even more preferably 0.59 or less, and still more preferably 0.57 or less. There is no particular limitation on the lower limit of the shrinkage factor (g'), and it may be below the detection limit, but it is preferably 0.30 or more, more preferably 0.33 or more, even more preferably 0.35 or more, and still more preferably 0.45 or more. A modified conjugated diene-based polymer having a shrinkage factor (g') in this range tends to have excellent processability when made into a vulcanizate.

[0015] Since the shrinkage factor (g') tends to depend on the degree of branching, it is possible to control the shrinkage factor (g'), for example, using the degree of branching as an index. Specifically, when a modified conjugated diene polymer has a degree of branching of 6, its shrinkage factor (g') tends to be 0.59 or more and 0.63 or less, and when a modified conjugated diene polymer has a degree of branching of 8, its shrinkage factor (g') tends to be 0.45 or more and 0.59 or less. The shrinkage factor (g') is measured by the method described in the examples below.

[0016] <Conjugated diene polymer chain> The conjugated diene polymer chain of the present embodiment is a structural unit of a modified conjugated diene polymer, and is, for example, a structural unit derived from a conjugated diene polymer produced by reacting a conjugated diene polymer with a coupling agent, which will be described later. The conjugated diene polymer chain of the present embodiment is preferably bonded to a coupling residue 1, which will be described later.

[0017] <Coupling Residue> The coupling residue of the present embodiment is a structural unit of the modified conjugated diene polymer that is bonded to a conjugated diene polymer chain, and is, for example, a structural unit derived from a coupling agent that is generated by reacting a conjugated diene polymer described below with a coupling agent.

[0018] The modified conjugated diene polymer of this embodiment preferably has branches, with a degree of branching of 5 or more. Furthermore, the modified conjugated diene polymer more preferably has one or more coupling residues and conjugated diene polymer chains bonded to the coupling residues, and furthermore, the branches more preferably include branches in which five or more conjugated diene polymer chains are bonded to one coupling residue. By specifying the structure of the modified conjugated diene polymer so that the degree of branching is 5 or more and the branches include branches in which five or more conjugated diene polymer chains are bonded to one coupling residue, the shrinkage factor (g') can be more reliably reduced to less than 0.64.

[0019] The modified conjugated diene polymer of this embodiment preferably has branches, with a degree of branching of 6 or more. Furthermore, the modified conjugated diene polymer preferably has one or more coupling residues and conjugated diene polymer chains bonded to the coupling residues, and more preferably includes branches in which six or more conjugated diene polymer chains are bonded to one coupling residue. By specifying the structure of the modified conjugated diene polymer so that the degree of branching is 6 or more and the branch includes branches in which six or more conjugated diene polymer chains are bonded to one coupling residue, the shrinkage factor (g') can be set to 0.63 or less.

[0020] The modified conjugated diene polymer of this embodiment has branches, and more preferably has a degree of branching of 7 or more, and even more preferably has a degree of branching of 8 or more. The upper limit of the degree of branching is not particularly limited, but is preferably 18 or less. Furthermore, the modified conjugated diene polymer has one or more coupling residues and conjugated diene polymer chains bonded to the coupling residues. Furthermore, the modified conjugated diene polymer more preferably includes branches in which seven or more conjugated diene polymer chains are bonded to one coupling residue, and even more preferably includes branches in which eight or more conjugated diene polymer chains are bonded to one coupling residue. The number of conjugated diene polymer chains bonded to one coupling residue can be confirmed from the value of the contraction factor (g'). The contraction factor (g') can be set to 0.59 or less by specifying the structure of the modified conjugated diene polymer so that the degree of branching is 8 or more and the branch includes branches in which eight or more conjugated diene polymer chains are bonded to one coupling residue.

[0021] Furthermore, the modified conjugated diene polymer of this embodiment preferably contains a nitrogen atom and a silicon atom. This results in the effect of this embodiment of being superior in processability when vulcanized, and the resulting vulcanized product tends to have a better balance between low hysteresis loss and wet skid resistance, as well as better abrasion resistance. The presence of nitrogen atoms in the modified conjugated diene polymer can be confirmed by the presence or absence of adsorption to a specific column using the method described in the Examples below. Furthermore, the presence of silicon atoms in the modified conjugated diene polymer can be confirmed by metal analysis using the method described in the Examples below.

[0022] Furthermore, the modified conjugated diene polymer preferably contains a silicon atom, and more preferably, at least one silicon atom contained in the modified conjugated diene polymer constitutes an alkoxysilyl group or a silanol group having 1 to 20 carbon atoms. This tends to make the effects of this embodiment more pronounced. Furthermore, from the viewpoint that the modified conjugated diene polymer may react with air to generate hydrogen halide, it is preferable that the modified conjugated diene polymer does not contain a halogen.

[0023] It is preferable that at least one end of the five or more conjugated diene polymer chains is bonded to a silicon atom of the respective coupling residue. This tends to make the effects of this embodiment more pronounced. In this case, the ends of a plurality of conjugated diene polymer chains may be bonded to one silicon atom. Alternatively, an end of a conjugated diene polymer chain and an alkoxy group or hydroxyl group having 1 to 20 carbon atoms may be bonded to one silicon atom, and as a result, that one silicon atom may constitute an alkoxysilyl group or silanol group having 1 to 20 carbon atoms. From the viewpoint that hydrogen halide may be generated by reaction with air, it is preferable that the coupling residue does not contain a halogen.

[0024] In this embodiment, the modified conjugated diene polymer or the conjugated diene polymer described below can be further hydrogenated in an inert solvent to convert all or part of the double bonds to saturated hydrocarbons. In this case, heat resistance and weather resistance are improved, product degradation during processing at high temperatures can be prevented, and the rubber's dynamic performance tends to be improved. As a result, the polymer exhibits even better performance in various applications, such as automotive applications. More specifically, the hydrogenation rate of the unsaturated double bonds based on the conjugated diene compound can be selected arbitrarily depending on the purpose and is not particularly limited. When used as a vulcanizate, it is preferable that the double bonds of the conjugated diene moiety remain partially. From this perspective, the hydrogenation rate of the conjugated diene moiety in the conjugated diene polymer is preferably 3.0% to 70%, more preferably 5.0% to 65%, and even more preferably 10% to 60%. In particular, selective hydrogenation of vinyl groups tends to improve heat resistance and dynamic performance. The hydrogenation rate can be determined by nuclear magnetic resonance (NMR) spectroscopy.

[0025] The modified conjugated diene copolymer of this embodiment can be an oil-extended polymer to which an extender oil has been added. Whether the modified conjugated diene copolymer of this embodiment is non-oil-extended or oil-extended, from the viewpoints of processability when made into a rubber vulcanizate and abrasion resistance when made into a vulcanizate, the Mooney viscosity measured at 100°C of the modified conjugated diene copolymer of this embodiment is preferably 20 or more and 100 or less, more preferably 30 or more and 80 or less. The Mooney viscosity is measured by the method described in the examples below.

[0026] The weight average molecular weight of the modified conjugated diene polymer is 20×10 ４ 300 x 10 or more ４ or less, preferably 50×10 ４ or more, more preferably 64×10 ４ More preferably, it is 80×10 ４ The weight average molecular weight is preferably 250×10 ４ or less, preferably 180×10 ４ or less, and more preferably 150×10 ４ The weight average molecular weight is 20×10 or less. ４ By virtue of the weight average molecular weight being 300×10 or more, the effect of this embodiment is achieved, in the case of a vulcanizate, by which a balance between low hysteresis loss and wet skid resistance and excellent abrasion resistance is achieved. ４ When the weight average molecular weight is not more than 1000 ppm, the processability and filler dispersibility when vulcanized are excellent, and practically sufficient fracture properties can be obtained. The weight average molecular weights of the modified conjugated diene polymer and the conjugated diene polymer described later are measured by the method described in the examples described later.

[0027] The modified conjugated diene polymer has a molecular weight of 200×10 relative to the total amount (100% by mass) of the modified conjugated diene. ４ Above 500 x 10 ４The modified conjugated diene polymer contains 0.25% by mass or more and 30% by mass or less of the modified conjugated diene polymer (hereinafter also referred to as "specific high molecular weight component") having a molecular weight of 0.25% by mass or more and 30% by mass or less. This results in the advantageous effect of this embodiment, in which the vulcanizate has a good balance between low hysteresis loss and wet skid resistance, and excellent abrasion resistance. The modified conjugated diene polymer contains preferably 1.0% by mass or more of the specific high molecular weight component, more preferably 1.4% by mass or more, even more preferably 1.75% by mass or more, still more preferably 2.0% by mass or more, even more preferably 2.15% by mass or more, and extremely preferably 2.5% by mass or more. The modified conjugated diene polymer also contains preferably 28% by mass or less of the specific high molecular weight component, more preferably 25% by mass or less, even more preferably 20% by mass or less, and even more preferably 18% by mass or less. In this specification, the "molecular weight" refers to the molecular weight in terms of standard polystyrene obtained by GPC (gel permeation chromatography). To obtain a modified conjugated diene polymer having a specific high molecular weight component content within this range, it is preferable to control the reaction conditions in the polymerization step and reaction step described below. For example, in the polymerization step, the amount of the organomonolithium compound used as a polymerization initiator, described below, may be adjusted, as follows. In the polymerization step described below, whether the polymerization is performed in a continuous or batchwise manner, a method having a residence time distribution, i.e., a widening of the time distribution of the growth reaction, is preferable. Specific methods in the continuous method include using a tank reactor equipped with an agitator as a back-mix reactor, preferably a complete mixing reactor, in which the reactor is vigorously mixed with an agitator; a method in which a tubular reactor is partially recirculated; a method in which the polymerization initiator is fed to a monomer inlet or nearby, as well as a polymerization initiator inlet midway through the polymerization reactor; and a method combining a tank reactor and a tubular reactor. These methods are intended to widen the residence time distribution and convert polymer components with long residence times into high molecular weight components. Specific examples of the batchwise method include a method in which the polymerization initiator is fed continuously or intermittently from the start of polymerization through the middle of polymerization, or continuously or intermittently at the start of polymerization and / or during polymerization.In this method, the polymer polymerized from the start of polymerization when the polymerization initiator is first fed becomes a high-molecular-weight component, resulting in a molecular weight difference between it and the polymer initiated later. More specifically, by continuously feeding an amount of polymerization initiator corresponding to the target molecular weight relative to the monomers, for example, up to a conversion rate of 0% to 95%, a polymer with a broad molecular weight distribution tends to be obtained. The use of the above-described method also tends to increase the active ratio of living ends of the conjugated diene polymer before the reaction step, and also tends to produce a modified conjugated diene polymer with a high coupling rate (i.e., a high modification rate) after coupling. Among these methods, a back-mix reactor using a tank-type reactor equipped with an agitator and vigorously mixing the components with the agitator is more preferred. Furthermore, the temperature change from the end of the polymerization step until the addition of the coupling agent is preferably 10°C or less, more preferably 5°C or less.

[0028] In addition to controlling the reaction conditions in the polymerization step described above, the reaction conditions in the modification step can be controlled, for example, by setting the reaction time to, for example, 10 seconds or more, more preferably 30 seconds or more. Furthermore, the time between the end of the polymerization step and the start of the reaction step is preferably shorter, and even more preferably 5 minutes or less. This tends to facilitate the production of a high coupling rate, a high modification rate, and a high molecular weight component. Furthermore, the greater the number of functional groups in the coupling agent, the more likely the degree of branching in the resulting modified conjugated diene polymer deviates from the desired value if the amount of coupling agent added in the reaction step cannot be controlled within the desired range. Therefore, in order to produce a predetermined amount of high molecular weight component, it is preferable to appropriately control the amount of coupling agent added. To appropriately control the amount of coupling agent added, for example, it is preferable to dilute the coupling agent before adding it. The dilution concentration is preferably 0.1 mmol / L to 1.1 mol / L, and more preferably 1 mmol / L to 0.75 mol / L. When the difference in the added amounts is the same, the difference between the number of moles of the conjugated diene polymer and the number of moles of the coupling agent tends to be smaller when diluted. Furthermore, the water content of the diluting solvent is preferably 100 ppm by mass or less, more preferably 50 ppm by mass or less, even more preferably 30 ppm by mass or less, and even more preferably 10 ppm by mass or less. When the water content of the diluting solvent is 100 ppm by mass or less, the coupling agent reacts with water, reducing the functional groups in the coupling agent, which can suppress the difference between the number of moles of the conjugated diene polymer and the number of moles of the coupling agent, and tends to make it easier to obtain a high-molecular-weight component.

[0029] In the modified conjugated diene polymer, the molecular weight distribution (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 1.6 to 3.0. A modified conjugated diene polymer having a molecular weight distribution in this range tends to have better processability when vulcanized, and tends to have better wear resistance when vulcanized.

[0030] The number average molecular weight, weight average molecular weight, molecular weight distribution, and content of specific high molecular weight components for the modified conjugated diene polymer and the conjugated diene polymer described below are measured by the methods described in the examples described below.

[0031] The modified conjugated diene polymer of the present embodiment is preferably represented by the following general formula (I). In formula (I), D １ represents a diene polymer chain, and the weight average molecular weight of the diene polymer chain is 10 × 10 ４ ~100 x 10 ４ It is preferable that R １ ~R ３ each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms; R ４ and R ７ each independently represents an alkyl group having 1 to 20 carbon atoms; R ５ , R ８ , and R ９ each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; R ６ and R １０ each independently represents an alkylene group having 1 to 20 carbon atoms; R １１ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. m and x represent integers of 1 to 3, with x≦m, p represents 1 or 2, y represents an integer of 1 to 3, with y≦(p+1), and z represents an integer of 1 or 2. When there are multiple D １ , R １ ~R １１, m, p, x, y, and z are each independent and may be the same or different. i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, (i + j + k) is an integer of 3 to 10, and ((x × i) + (y × j) + (z × k)) is an integer of 5 to 30. A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of oxygen atoms, nitrogen atoms, silicon atoms, sulfur atoms, and phosphorus atoms, and having no active hydrogen. The hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. The organic group having no active hydrogen is an organic group that inactivates the active terminal of the conjugated diene polymer. Examples of such organic groups include a hydroxyl group (—OH), a secondary amino group (>NH), a primary amino group (—NH ２ The modified conjugated diene polymer represented by formula (1) is an organic group that does not have a functional group having active hydrogen, such as a sulfhydryl group (—SH). The modified conjugated diene polymer represented by formula (1) tends to have excellent processability when vulcanized, which is an effect of this embodiment, and tends to have an excellent balance between low hysteresis loss and wet skid resistance, and excellent abrasion resistance when vulcanized.

[0032] In the modified conjugated diene polymer of the present embodiment, A in formula (I) is preferably represented by any one of the following general formulae (II) to (V). In formula (II), B １ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. １ are each independent of each other.

[0033] In formula (III), B ２ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ３ represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ２ and B ３ are each independent of each other.

[0034] In formula (IV), B ４represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ４ are each independent of each other.

[0035] In formula (V), B ５ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ５ are each independent. When A is represented by any one of formulas (II) to (V), the effect of this embodiment tends to be that the processability when made into a vulcanizate is better, and when made into a vulcanizate, the balance between low hysteresis loss and wet skid resistance and the abrasion resistance tend to be better. In addition, the compound tends to be more readily available for practical use.

[0036] [Method for Producing Modified Conjugated Diene Polymer] The method for producing a modified conjugated diene polymer of this embodiment includes a polymerization step of polymerizing at least a conjugated diene compound using an organic monolithium compound as a polymerization initiator to obtain a conjugated diene polymer, and a reaction step of reacting the conjugated diene polymer and the active terminals of the conjugated diene polymer of this embodiment with a pentafunctional or higher reactive compound (hereinafter also referred to as a "coupling agent"). As the coupling agent, a pentafunctional or higher reactive compound having a nitrogen atom and a silicon atom is preferably used. Preferably, the method includes a reaction step of reacting a compound represented by the following general formula (VI) with In formula (VI), R １２ ~R １４ each independently represents a single bond or an alkylene group having 1 to 20 carbon atoms; R １５ ~R １８ , and R ２０ each independently represents an alkyl group having 1 to 20 carbon atoms; R １９ and R ２２ each independently represents an alkylene group having 1 to 20 carbon atoms; R ２１ represents an alkyl group or a trialkylsilyl group having 1 to 20 carbon atoms, m represents an integer of 1 to 3, and p represents 1 or 2. When a plurality of R １２ ~R ２２, m, and p are each independent and may be the same or different. i represents an integer of 0 to 6, j represents an integer of 0 to 6, k represents an integer of 0 to 6, and (i + j + k) is an integer of 3 to 10. A represents a hydrocarbon group having 1 to 20 carbon atoms, or an organic group having at least one atom selected from the group consisting of oxygen atoms, nitrogen atoms, silicon atoms, sulfur atoms, and phosphorus atoms, and having no active hydrogen. The hydrocarbon group represented by A includes saturated, unsaturated, aliphatic, and aromatic hydrocarbon groups. The organic group having no active hydrogen is an organic group that inactivates the active terminal of the conjugated diene polymer. Examples of such organic groups include a hydroxyl group (—OH), a secondary amino group (>NH), a primary amino group (—NH ２ ), or a functional group having an active hydrogen such as a sulfhydryl group (-SH).

[0037] [Polymerization Step] In the polymerization step of the present embodiment, an organic monolithium compound is used as a polymerization initiator to polymerize at least a conjugated diene compound to obtain a conjugated diene polymer. The polymerization step is preferably polymerization by a propagation reaction due to a living anionic polymerization reaction, which tends to produce a conjugated diene polymer having an active terminal and a modified diene polymer with a high modification rate.

[0038] <Conjugated Diene Polymer> The conjugated diene polymer of this embodiment is obtained by polymerizing at least a conjugated diene compound, and optionally by copolymerizing both a conjugated diene compound and a vinyl-substituted aromatic compound. The conjugated diene compound of this embodiment is not particularly limited as long as it is a polymerizable monomer, but is preferably a conjugated diene compound containing 4 to 12 carbon atoms per molecule, and more preferably a conjugated diene compound containing 4 to 8 carbon atoms. Examples of such conjugated diene compounds include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.

[0039] The vinyl-substituted aromatic compound is not particularly limited as long as it is a monomer copolymerizable with a conjugated diene compound, but a monovinyl aromatic compound is preferred. Examples of the monovinyl aromatic compound include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.

[0040] If allenes, acetylenes, etc. are contained as impurities in the conjugated diene compound and / or vinyl-substituted aromatic compound, they may inhibit the reaction in the reaction step described below. Therefore, the total content concentration (mass) of these impurities is preferably 200 ppm or less, more preferably 100 ppm or less, and even more preferably 50 ppm or less. Examples of allenes include propadiene and 1,2-butadiene. Examples of acetylenes include ethyl acetylene and vinyl acetylene.

[0041] The conjugated diene polymer may be a random copolymer or a block copolymer. In order to make the conjugated diene polymer into a rubber-like polymer, the conjugated diene compound is preferably used in an amount of 40 mass% or more, more preferably 55 mass% or more, based on the total amount of the monomers of the conjugated diene polymer.

[0042] Examples of random copolymers include, but are not limited to, random copolymers composed of two or more conjugated diene compounds such as butadiene-isoprene random copolymers, butadiene-styrene random copolymers, isoprene-styrene random copolymers, and random copolymers composed of conjugated dienes and vinyl-substituted aromatic compounds such as butadiene-isoprene-styrene random copolymers. The composition distribution of each monomer in the copolymer chain is not particularly limited, and examples include completely random copolymers that are close to a statistically random composition and tapered (gradient) random copolymers in which the composition is distributed in a tapered pattern. The bonding mode of the conjugated diene, i.e., the composition of 1,4-bonds, 1,2-bonds, etc., may be uniform or may have a distribution.

[0043] Examples of block copolymers include, but are not limited to, type 2 block copolymers (diblock) consisting of two blocks, type 3 block copolymers (triblock) consisting of three blocks, and type 4 block copolymers (tetrablock) consisting of four blocks. A polymer constituting one block may be a polymer consisting of one type of monomer, or a copolymer consisting of two or more types of monomers. For example, if a polymer block consisting of 1,3-butadiene is represented by "B," a copolymer of 1,3-butadiene and isoprene is represented by "B / I," a copolymer of 1,3-butadiene and styrene is represented by "B / S," and a polymer block consisting of styrene is represented by "S," then the copolymers may be represented as B-B / I2 block copolymers, B-B / S2 block copolymers, S-B2 block copolymers, B-B / S-S3 block copolymers, S-B-S3 block copolymers, S-B-S-B4 block copolymers, etc.

[0044] In the above formula, the boundaries of each block do not necessarily need to be clearly distinguished. When one polymer block is a copolymer consisting of two types of monomers A and B, A and B may be distributed uniformly or in a tapered pattern within the block.

[0045] <Polymerization Initiator> At least an organomonolithium compound is used as the polymerization initiator in this embodiment. Examples of the organomonolithium compound include, but are not limited to, low molecular weight compounds and solubilized oligomeric organomonolithium compounds. Furthermore, examples of the organomonolithium compound include compounds having a carbon-lithium bond, a nitrogen-lithium bond, and a tin-lithium bond in terms of the bonding mode between the organic group and the lithium.

[0046] The amount of the organic monolithium compound used as a polymerization initiator is preferably determined based on the molecular weight of the target conjugated diene polymer or modified conjugated diene polymer. The amount of the monomer, such as the conjugated diene compound, used relative to the amount of the polymerization initiator tends to be related to the degree of polymerization, i.e., the number average molecular weight and / or the weight average molecular weight. Therefore, to increase the molecular weight, it is advisable to adjust the amount of the polymerization initiator to decrease, and to decrease the molecular weight, it is advisable to adjust the amount of the polymerization initiator to increase.

[0047] The organomonolithium compound is preferably an alkyllithium compound having a substituted amino group or a dialkylaminolithium compound, because it can be used as a method for introducing a nitrogen atom 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 can be obtained.

[0048] 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 that have an amino group that does not have an active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium. Examples of alkyllithium compounds that have an amino group with a structure in which the active hydrogen is protected include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0049] 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.

[0050] 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.

[0051] The organic monolithium 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 terminal 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. From the viewpoints of industrial availability and ease of control of the polymerization reaction, n-butyllithium and sec-butyllithium are preferred as the alkyllithium compound.

[0052] These organomonolithium compounds may be used alone or in combination of two or more. They may also be used in combination with other organometallic compounds. Examples of the 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. Examples of alkaline earth metal alkoxides, sulfonates, carbonates, and amides of alkaline earth metals are also included. Examples of organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Examples of other organometallic compounds include organoaluminum compounds.

[0053] In the polymerization step, the polymerization reaction mode may be, but is not limited to, a batchwise mode (also referred to as a "batchwise mode") or a continuous mode. In a continuous mode, one or more connected reactors may be used. A continuous reactor may be, for example, a tank-type or tubular reactor equipped with a stirrer. In a continuous mode, preferably, a monomer, an inert solvent, and a polymerization initiator are continuously fed into the reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is continuously discharged. In a batch mode, a tank-type reactor equipped with a stirrer may be used. In a batch mode, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, a monomer is continuously or intermittently added during the polymerization, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is discharged after the polymerization is completed. In the present embodiment, in order to obtain a conjugated diene-based polymer having a high proportion of active ends, a continuous mode is preferred, in which the polymer can be continuously discharged and subjected to the next reaction in a short period of time.

[0054] The polymerization step is preferably carried out in an inert solvent. Examples of the solvent include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene, and hydrocarbons consisting of mixtures thereof. Treating impurities such as allenes and acetylenes with an organometallic compound before subjecting the mixture to the polymerization reaction tends to produce a conjugated diene polymer having a high concentration of active ends, and is therefore preferred because it tends to produce a modified conjugated diene polymer with a high modification rate.

[0055] In the polymerization step, a polar compound may be added. Aromatic vinyl compounds can be randomly copolymerized with conjugated diene compounds, and they tend to be useful as vinylating agents for controlling the microstructure of the conjugated diene moiety. They also tend to be effective in accelerating the polymerization reaction.

[0056] Examples of polar compounds that can be used 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 compounds may be used alone or in combination of two or more.

[0057] The amount of polar compound used is not particularly limited and can be selected depending on the purpose, etc., but is preferably 0.01 mol to 100 mol per mol of polymerization initiator. Such polar compounds (vinylating agents) can be used in an appropriate amount depending on the desired vinyl bond content as an adjuster for the microstructure of the conjugated diene portion of the polymer. Many polar compounds also have an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and tend to be used as an adjuster for the distribution of the aromatic vinyl compound or the amount of styrene blocks. A method for randomizing a conjugated diene compound and an aromatic vinyl compound may be, for example, as described in JP-A-59-140211, in which a copolymerization reaction is initiated with all of the styrene and a portion of the 1,3-butadiene, and the remaining 1,3-butadiene is intermittently added during the copolymerization reaction.

[0058] In the polymerization step, the polymerization temperature is preferably a temperature at which living anionic polymerization proceeds, and from the viewpoint of productivity, it is more preferably 0°C or higher, and even more preferably 120°C or lower. By keeping the temperature in this range, it tends to be possible to ensure a sufficient amount of reaction of the coupling agent with the active terminals after the polymerization is completed. Even more preferably, it is 50°C or higher and 100°C or lower.

[0059] The conjugated diene polymer obtained in the polymerization step before the reaction step preferably has a Mooney viscosity measured at 110°C of 10 or more and 90 or less, more preferably 15 or more and 85 or less, and even more preferably 20 or more and 60 or less. Within this range, the modified conjugated diene polymer of the present embodiment tends to have excellent processability and abrasion resistance.

[0060] The amount of bound conjugated diene in the conjugated diene polymer or modified conjugated diene polymer of this embodiment is not particularly limited, but is preferably 40% by mass or more and 100% by mass or less, and more preferably 55% by mass or more and 80% by mass or less. The amount of bound aromatic vinyl in the conjugated diene polymer or modified conjugated diene polymer of this embodiment is also not particularly limited, but is preferably 0% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 45% by mass or less. When the amount of bound conjugated diene and the amount of bound aromatic vinyl are within the above ranges, the resulting vulcanizate tends to have a better balance between low hysteresis loss and wet skid resistance, as well as better abrasion resistance and fracture properties. The amount of bound aromatic vinyl can be measured by ultraviolet absorption of the phenyl group, from which the amount of bound conjugated diene can also be determined. Specifically, the amount is measured according to the method described in the Examples below.

[0061] In the conjugated diene polymer or modified conjugated diene polymer of this embodiment, the vinyl bond content in the conjugated diene bond units is not particularly limited, but is preferably 10 mol % to 75 mol %, and more preferably 20 mol % to 65 mol %. When the vinyl bond content is within the above range, the resulting vulcanizate tends to have a better balance between low hysteresis loss and wet skid resistance, as well as better abrasion resistance and breaking strength. Here, when the modified diene polymer is a copolymer of butadiene and styrene, the vinyl bond content (1,2-bond content) in the butadiene bond units can be determined by the Hampton method (R.R. Hampton, Analytical Chemistry, 21, 923 (1949)). Specifically, it is measured by the method described in the Examples below.

[0062] Regarding the microstructure of the modified conjugated diene polymer, when the bond amounts in the modified conjugated diene polymer are within the above-mentioned ranges and the glass transition temperature of the modified conjugated diene polymer is within the range of -45°C or higher and -15°C or lower, a vulcanizate with an even better balance between low hysteresis loss and wet skid resistance tends to be obtained. Regarding the glass transition temperature, a DSC curve is recorded while raising the temperature within a predetermined temperature range in accordance with ISO 22768:2006, and the peak top (inflection point) of the DSC differential curve is taken as the glass transition temperature. Specifically, it is measured by the method described in the Examples below.

[0063] When the modified conjugated diene polymer of the present embodiment is a conjugated diene-aromatic vinyl copolymer, it is preferable that the number of blocks in which 30 or more aromatic vinyl units are linked is small or that there is no such block. More specifically, when the copolymer is a butadiene-styrene copolymer, the copolymer 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. In this known method, the amount of blocks in which 30 or more aromatic vinyl units are linked is preferably 5.0 mass% or less, more preferably 3.0 mass% or less, based on the total amount of the copolymer.

[0064] When the conjugated diene polymer of this embodiment is a conjugated diene-aromatic vinyl copolymer, it is preferable that the proportion of aromatic vinyl units present alone is high. Specifically, when the copolymer is a butadiene-styrene copolymer, when the copolymer is decomposed by an ozonolysis method known as the Tanaka et al. method (Polymer, 22, 1721 (1981)) and the styrene chain distribution is analyzed by GPC, it is preferable that the amount of isolated styrene is 40% by mass or more relative to the total amount of bound styrene, and the amount of chain styrene structures having 8 or more styrene chains is 5.0% by mass or less. In this case, the resulting vulcanized rubber has excellent performance, particularly low hysteresis loss.

[0065] [Reaction Step] In the reaction step of this embodiment, a pentafunctional or higher reactive compound (hereinafter also referred to as a "coupling agent") is reacted with the active terminal of the conjugated diene polymer of this embodiment to obtain a modified conjugated diene polymer of this embodiment in which coupling residues are bonded to five or more molecules of the conjugated diene polymer. It is preferable to react a pentafunctional or higher reactive compound having a nitrogen atom and a silicon atom.

[0066] <Coupling Agent> The coupling agent used in the reaction step of this embodiment may be any structure as long as it is a pentafunctional or higher reactive compound, but is preferably a pentafunctional or higher reactive compound having a nitrogen atom and a silicon atom, and preferably has at least three silicon-containing functional groups. A more preferred coupling agent is one in which at least one silicon atom constitutes an alkoxysilyl group or silanol group having 1 to 20 carbon atoms, and more preferably a compound represented by the above formula (VI) as the coupling agent.

[0067] The alkoxysilyl group of the coupling agent tends to react with, for example, the active terminal of the conjugated diene polymer, dissociating the alkoxylithium and forming a bond between the terminal of the conjugated diene polymer chain and the silicon of the coupling residue. The number of alkoxysilyl groups in the coupling residue is the total number of SiOR groups in one molecule of the coupling agent minus the number of SiOR groups reduced by the reaction. Furthermore, the azasilacycle group of the coupling agent forms an >N-Li bond and a bond between the terminal of the conjugated diene polymer and the silicon of the coupling residue. Note that the >N-Li bond tends to easily become >NH and LiOH upon exposure to water or the like during finishing. Furthermore, any alkoxysilyl groups remaining unreacted in the coupling agent tend to easily become silanols (Si-OH groups) upon exposure to water or the like during finishing.

[0068] In the reaction step, when the active end of a conjugated diene polymer has three alkoxy groups per silicon atom, i.e., 1 mole of trialkoxysilane group is reacted with 3 moles of the conjugated diene polymer, up to 2 moles of the conjugated diene polymer react, but 1 mole of the alkoxy group tends to remain unreacted. This is confirmed by the fact that 1 mole of the conjugated diene polymer remains unreacted. Note that by reacting a large number of alkoxysilane groups, it tends to be possible to suppress large changes in polymer viscosity due to condensation reactions during finishing and storage. In particular, when the modified conjugated diene copolymer contains 3 or more compounds in which 2 moles of conjugated diene copolymer react with 1 mole of trialkoxysilane group, i.e., the branching degree is 6 or more, and no other reactive alkoxy groups are present in the modified conjugated diene copolymer, it tends to be possible to suppress the condensation reaction.

[0069] The coupling agent is not limited to the following, but examples thereof include tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-tripropoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, 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-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris(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-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, 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, and tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate.

[0070] The reaction temperature in the reaction step is preferably the same as the polymerization temperature of the conjugated diene polymer, more preferably from 0° C. to 120° C., and even more preferably from 50° C. to 100° C. The temperature change from the end of the polymerization step to the addition of the coupling agent is preferably 10° C. or less, more preferably 5° C. or less.

[0071] The reaction time in the reaction step is preferably 10 seconds or more, more preferably 30 seconds or more. The time from the end of the polymerization step to the start of the reaction step is preferably shorter, more preferably within 5 minutes. This tends to result in a high coupling rate and a high modification rate.

[0072] The mixing in the reaction step may be performed by mechanical stirring, stirring with a static mixer, or the like. When the polymerization step is continuous, it is preferable that the reaction step is also continuous. The reactor used in the reaction step may be, for example, a tank type or a tubular type equipped with a stirrer. The coupling agent may be diluted with an inert solvent and continuously supplied to the reactor. When the polymerization step is batchwise, the coupling agent may be charged into the polymerization reactor, or may be transferred to a separate reactor and the reaction step may be carried out.

[0073] In formula (VI), A is preferably represented by any one of the following general formulae (II) to (V). In formula (II), B １ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. １ are each independent of each other.

[0074] In formula (III), B ２ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, B ３ represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ２ and B ３ are each independent of each other.

[0075] In formula (IV), B ４ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ４ are each independent of each other.

[0076] In formula (V), B ５ represents a single bond or a hydrocarbon group having 1 to 20 carbon atoms, and a represents an integer of 1 to 10. ５ When A is represented by any one of formulas (II) to (V), a modified conjugated diene-based polymer of the present embodiment having better performance tends to be obtained.

[0077] When A in formula (VI) is represented by formula (II), examples of the coupling 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]-(3-trimethoxysilylpropyl)amine, 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-2-silacyclopentane)propyl]-(3-triethoxysilylpropyl)amine, tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tris( 3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-1,3-propanediamine, 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]-(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, tris(3 -triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, 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 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]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl tris[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, 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)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis[3-(2,2-dimethoxy -1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, 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-propane Diamine, tris(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-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-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, bis[3-(2,2-diethoxy-1-aza-2-silacyclo tris[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.

[0078] When A in formula (VI) is represented by formula (III), examples of the coupling 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.

[0079] When A in formula (VI) is represented by formula (IV), examples of the coupling 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 propyl]silane, bis[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2 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.

[0080] When A in formula (VI) is represented by formula (V), examples of the coupling 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.

[0081] In formula (VI), A is preferably represented by formula (II) or formula (III), and k is 0. Such coupling agents tend to be easily available, and also tend to improve the abrasion resistance and low hysteresis loss performance when the modified conjugated diene polymer is vulcanized. Examples of such coupling agents include, but are not limited to, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1

[0033] tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, and bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trismethoxysilylpropyl)-methyl-1,3-propanediamine.

[0082] In formula (VI), A is more preferably represented by formula (II) or formula (III), k is 0, and in formula (II) or formula (III), a is an integer of 2 to 10. This tends to result in better abrasion resistance and low hysteresis loss performance when vulcanized. Examples of such coupling agents include, but are not limited to, tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, 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.

[0083] The amount of the compound represented by formula (VI) added as a coupling agent can be adjusted so that the number of moles of the conjugated diene polymer to the number of moles of the coupling agent react in a desired stoichiometric ratio, which tends to achieve a desired degree of branching. Specifically, the number of moles of the polymerization initiator is preferably 5.0 times or more, more preferably 6.0 times or more, relative to the number of moles of the coupling agent. In this case, in formula (VI), the number of functional groups of the coupling agent ((m-1) x i + p x j + k) is preferably an integer of 5 to 10, and more preferably an integer of 6 to 10.

[0084] The greater the number of functional groups in the compound represented by formula (VI), the more likely the degree of branching in the resulting modified conjugated diene polymer deviates from the desired value if the amount of coupling agent added in the reaction step cannot be controlled within the desired range. Therefore, it is preferable to appropriately control the amount of coupling agent added. To appropriately control the amount of coupling agent added, for example, a method of diluting the coupling agent before adding it is preferred. When the deviation in the amount added is the same, the deviation between the number of moles of the conjugated diene polymer and the number of moles of the coupling agent tends to be smaller when the coupling agent is diluted. Furthermore, the water content of the diluting solvent is preferably 100 ppm by mass or less, more preferably 50 ppm by mass or less, even more preferably 30 ppm by mass or less, and even more preferably 10 ppm by mass or less. When the water content of the diluting solvent is 100 ppm by mass or less, the coupling agent reacts with water, reducing the functional groups in the coupling agent, which tends to suppress the deviation between the number of moles of the conjugated diene polymer and the number of moles of the coupling agent.

[0085] To obtain a modified conjugated diene polymer having a specific polymer component according to this embodiment, the molecular weight distribution (Mw / Mn) of the conjugated diene polymer is preferably 1.5 or more and 2.5 or less, more preferably 1.8 or more and 2.2 or less. Furthermore, it is preferable that the resulting modified conjugated diene polymer has a molecular weight curve measured by GPC in which a single peak is detected. In this case, the processability and abrasion resistance targeted by this embodiment tend to be more excellent.

[0086] The peak molecular weight of the modified conjugated diene polymer measured by GPC is Mp １ , the peak molecular weight of the conjugated diene polymer is Mp ２ In this case, it is preferable that the following formula is satisfied: １ / Mp ２ )<1.8×10-12×(Mp ２ -120 x 10 ４ ) 2+2 Mp ２ is 20 x 10 ４ Above 80 x 10 ４ , Mp １ is 30 x 10 ４ Above 150 x 10 ４The following is more preferred: １ and Mp ２ is determined by the method described in the Examples below.

[0087] In the modified conjugated diene polymer of this embodiment, the proportion of coupling polymer in the modified conjugated polymer is expressed as a modification rate. The modification rate is preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more. A modification rate of 30% by mass or more tends to provide excellent processability when vulcanized, and the vulcanized product tends to have better abrasion resistance and low hysteresis loss performance. In this embodiment, the proportion of coupling polymer is synonymous with the modification rate when the coupling residue has functional groups consisting of nitrogen and silicon. The modification rate is measured by the method described in the examples below.

[0088] In this embodiment, a condensation reaction step in which a condensation reaction is carried out in the presence of a condensation promoter can be provided after or before the reaction step.

[0089] The method for hydrogenating the conjugated diene portion of the modified conjugated diene polymer of this embodiment is not particularly limited, and known methods can be used. A suitable hydrogenation method is to blow gaseous hydrogen into a polymer solution in the presence of a catalyst. Examples of the catalyst include heterogeneous catalysts such as catalysts in which a noble metal is supported on a porous inorganic material; catalysts in which a salt of nickel, cobalt, or the like is solubilized and reacted with organoaluminum, and homogeneous catalysts such as catalysts using metallocenes such as titanocene. Among these, titanocene catalysts are preferred from the viewpoint of being able to select mild hydrogenation conditions. Furthermore, hydrogenation of aromatic groups can be carried out using a noble metal supported catalyst.

[0090] Specific examples of hydrogenation catalysts include, but are not limited to, (1) supported heterogeneous hydrogenation catalysts in which a metal such as Ni, Pt, Pd, or Ru is supported on carbon, silica, alumina, diatomaceous earth, or the like, (2) so-called Ziegler-type hydrogenation catalysts that use a transition metal salt such as an organic acid salt or an acetylacetone salt of Ni, Co, Fe, Cr, or the like, and a reducing agent such as an organoaluminum, and (3) so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, Zr, etc. Further examples of hydrogenation catalysts include known hydrogenation catalysts described in, for example, JP-B Nos. 42-8704, 43-6636, 63-4841, 1-37970, 1-53851, 2-9041, and JP-A No. 8-109219. Preferred hydrogenation catalysts include a reaction mixture of a titanocene compound and a reducing organometallic compound.

[0091] In the method for producing a modified conjugated diene polymer of this embodiment, a deactivator, a neutralizing agent, etc. may be added to the copolymer solution after the reaction step, if necessary. Examples of deactivators include, but are not limited to, water; alcohols such as methanol, ethanol, and isopropanol; and examples of neutralizing agents include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, with the majority being 10 carbon atoms); aqueous solutions of inorganic acids; and carbon dioxide gas.

[0092] 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.

[0093] In order to further improve the processability of the modified conjugated diene polymer of this embodiment, an extender oil can be added to the modified conjugated diene copolymer as needed. The method of adding the extender oil to the modified conjugated diene polymer is not limited to the following, but a preferred method involves adding the extender oil to the polymer solution, mixing, and desolvating the resulting oil-extended copolymer solution. Examples of extender oils include aromatic oils, naphthenic oils, and paraffin oils. Among these, from the viewpoints of environmental safety, oil bleed prevention, and wet grip properties, aromatic substitute oils having a polycyclic aromatic (PCA) component content of 3% by mass or less according to the IP346 method are preferred. Examples of the aroma substitute oil include TDAE (Treated Distillate Aromatic Extracts), MES (Mild Extraction Solvate), and RAE (Residual Aromatic Extracts) as described in Kautschuk Gummi Kunststoffe 52 (12) 799 (1999). The amount of the extender oil added is not particularly limited, but is preferably 10 parts by mass or more and 60 parts by mass or less, and more preferably 20 parts by mass or more and 37.5 parts by mass or less, per 100 parts by mass of the modified conjugated diene polymer.

[0094] The modified conjugated diene polymer of the present embodiment can be obtained from the polymer solution by any known method, including, for example, a method in which the solvent is separated by steam stripping or the like, the polymer is filtered, and then the polymer is dehydrated and dried to obtain the polymer, a method in which the polymer is concentrated in a flashing tank and then devolatilized using a vent extruder or the like, and a method in which the polymer is directly devolatilized using a drum dryer or the like.

[0095] The modified conjugated diene polymer of this embodiment is preferably used as a vulcanizate. Examples of vulcanizates include tires, hoses, shoe soles, vibration-proof rubber, automotive parts, and vibration-isolating rubber, as well as resin-reinforced rubbers such as high-impact polystyrene and ABS resin. In particular, the modified conjugated diene polymer is preferably used in tire tread rubber compositions. The vulcanizate can be obtained, for example, by kneading the modified conjugated diene polymer of this embodiment with, as necessary, an inorganic filler such as a silica-based inorganic filler or carbon black, a rubber-like polymer other than the modified conjugated diene polymer of this embodiment, a silane coupling agent, a rubber softener, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, etc. to form a modified conjugated diene polymer composition, and then heating and vulcanizing the resulting mixture.

[0096] [Rubber Composition] The rubber composition of this embodiment includes a rubber component and 5.0 parts by mass or more and 150 parts by mass or less of a filler per 100 parts by mass of the rubber component. The rubber component also includes 10% by mass or more of the modified conjugated diene polymer described above relative to the total amount (100% by mass) of the rubber component. The filler preferably includes a silica-based inorganic filler. By dispersing the silica-based inorganic filler in the rubber composition, the rubber composition tends to have better processability when vulcanized, and the resulting vulcanized product tends to have a better balance between low hysteresis loss and wet skid resistance, as well as better abrasion resistance and fracture strength. The rubber composition of this embodiment also preferably includes a silica-based inorganic filler when used in vulcanized rubber applications such as tires, automotive parts such as vibration-proof rubber, and shoes.

[0097] In the rubber composition, a rubbery polymer other than the modified conjugated diene polymer of this embodiment (hereinafter simply referred to as a "rubbery polymer") can be used in combination with the branched modified diene polymer of this embodiment. Examples of such rubbery polymers include, but are not limited to, conjugated diene polymers or hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, block copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, non-diene polymers, and natural rubber. Specific examples of rubbery polymers include, but are not limited to, styrene elastomers such as butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymers or hydrogenated products thereof, and styrene-isoprene block copolymers or hydrogenated products thereof, and acrylonitrile-butadiene rubber or hydrogenated products thereof.

[0098] Examples of non-diene polymers include, but are not limited to, olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber, butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0099] The natural rubber is not limited to the following, but examples thereof include smoked sheets RSS3 to 5, SMR, and epoxidized natural rubber.

[0100] The various rubbery polymers described above may be modified rubbers to which polar functional groups such as hydroxyl groups, amino groups, etc. When used for tires, butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber are preferably used.

[0101] From the viewpoint of a balance between performance and processing characteristics, the weight average molecular weight of the rubber polymer is preferably 2,000 to 2,000,000, and more preferably 5,000 to 1,500,000. Low molecular weight rubber polymers, so-called liquid rubbers, can also be used. These rubber polymers may be used alone or in combination of two or more.

[0102] In the case of preparing a rubber composition containing the modified conjugated diene polymer and the rubbery polymer of this embodiment, the 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 50 / 50 to 80 / 20. Therefore, the rubber component preferably contains 10 to 100 parts by mass of the modified conjugated diene polymer, more preferably 20 to 90 parts by mass, and even more preferably 50 to 80 parts by mass, based on the total amount (100 parts by mass) of the rubber component. When the (modified conjugated diene polymer / rubbery polymer) content is within the above range, the resulting vulcanizate exhibits an excellent balance between low hysteresis loss and wet skid resistance, as well as excellent abrasion resistance, and satisfactory breaking strength.

[0103] 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. These may be used alone or in combination of two or more.

[0104] The content of the filler in the rubber composition is 5.0 parts by mass or more and 150 parts by mass or less, and preferably 20 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the rubber component containing the modified conjugated diene-based polymer. The content of the filler is 5.0 parts by mass or more from the viewpoint of exhibiting the effect of adding the filler, and is 150 parts by mass or less from the viewpoint of sufficiently dispersing the filler and making the processability and mechanical strength of the composition practically sufficient.

[0105] The silica-based inorganic filler is not particularly limited, and known fillers can be used.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 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0106] Specific 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. Other examples include silica-based inorganic fillers with hydrophobic surfaces and mixtures of silica-based inorganic fillers with non-silica-based inorganic fillers. Among these, silica and glass fiber are preferred from the viewpoints of strength and abrasion resistance, and silica is more preferred. Examples of silica include dry silica, wet silica, and synthetic silicate silica. Among these silicas, wet silica is preferred from the viewpoint of achieving an excellent balance between the effect of improving fracture properties and wet skid resistance.

[0107] From the viewpoint of obtaining practically good wear resistance and fracture properties of the rubber composition, 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 or less) and a silica-based inorganic filler having a relatively large specific surface area (for example, 200 m ２ In this embodiment, a silica-based inorganic filler having a relatively large specific surface area (for example, 200 m ２ / g or more) is used, the modified conjugated diene polymer improves the dispersibility of the silica, is particularly effective in improving the abrasion resistance, and tends to be able to achieve a high level of balance between good fracture properties and low hysteresis loss.

[0108] The content of the silica-based inorganic filler in the rubber composition is 5.0 parts by mass or more and 150 parts by mass or less, and preferably 20 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the rubber component containing the modified conjugated diene polymer. The content of the silica-based inorganic filler is 5.0 parts by mass or more from the viewpoint of exhibiting the effect of adding the inorganic filler, and is 150 parts by mass or less from the viewpoint of sufficiently dispersing the inorganic filler and making the processability and mechanical strength of the composition practically sufficient.

[0109] The carbon black is not limited to the following, but examples thereof include 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 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.

[0110] The amount of carbon black is preferably 0.5 parts by mass or more and 100 parts by mass or less, more preferably 3.0 parts by mass or more and 100 parts by mass or less, and even more preferably 5.0 parts by mass or more and 50 parts by mass or less, per 100 parts by mass of the rubber component containing the modified conjugated diene polymer. The amount of carbon black is preferably 0.5 parts by mass or more from the viewpoint of realizing performance required for applications such as tires, such as dry grip performance and electrical conductivity, and is preferably 100 parts by mass or less from the viewpoint of dispersibility.

[0111] Metal oxides refer to solid particles whose main constituent unit is the chemical formula MxOy (M represents a metal atom, and x and y each independently represent an integer of 1 to 6). Examples of metal oxides include, but are not limited to, alumina, titanium oxide, magnesium oxide, and zinc oxide. Examples of metal hydroxides include, but are not limited to, aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0112] The rubber composition may contain a silane coupling agent. The silane coupling agent has the function of strengthening the interaction between the rubber component and the inorganic filler, and has groups that have affinity or bonding properties for both the rubber component and the silica-based inorganic filler. A compound having a sulfur-bonding moiety and an alkoxysilyl group or a silanol group moiety in one molecule is preferred. Examples of such compounds include bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0113] The content of the silane coupling agent is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and even more preferably 1.0 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the inorganic filler. When the content of the silane coupling agent is within the above range, the effect of the addition of the silane coupling agent tends to be more pronounced.

[0114] The rubber composition may contain a rubber softener to improve its processability. Mineral oil or a liquid or low-molecular-weight synthetic softener is preferred as the rubber softener. Mineral oil-based rubber softeners, known as process oils or extender oils, which are used to soften rubber, increase its volume, and improve its processability, are mixtures of aromatic rings, naphthenic rings, and paraffin chains. Those in which the carbon number of the paraffin chains accounts for 50% or more of the total carbon atoms are called paraffinic, those in which the carbon number of the naphthenic rings accounts for 30% to 45% of the total carbon atoms are called naphthenic, and those in which the aromatic carbon number accounts for more than 30% of the total carbon atoms are called aromatic. When the conjugated diene polymer of this embodiment is a copolymer of a conjugated diene compound and a vinyl aromatic compound, a rubber softener having an appropriate aromatic content is preferred because it tends to be compatible with the copolymer.

[0115] 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 containing the modified conjugated diene polymer. When the content of the rubber softener is 100 parts by mass or less per 100 parts by mass of the rubber component, bleed-out tends to be suppressed, and stickiness of the surface of the rubber composition tends to be suppressed.

[0116] The method for mixing the modified conjugated diene polymer with other rubbery polymers, silica-based inorganic fillers, carbon black or other fillers, and additives such as silane coupling agents and rubber softeners is not limited to the following, but examples include melt-kneading methods using common mixers such as open rolls, Banbury mixers, kneaders, single-screw extruders, twin-screw extruders, and multi-screw extruders, and methods in which the components are dissolved and mixed and then the solvent is removed by heating. Of these, melt-kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferred from the standpoint of productivity and good kneading ability. Furthermore, either a method in which the rubber component, other fillers, silane coupling agents, and additives are kneaded all at once, or a method in which they are mixed in multiple batches, can be used.

[0117] The rubber composition may be vulcanized with a vulcanizing agent to form a vulcanized composition. Examples of vulcanizing agents include, but are not limited to, 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. The content of the vulcanizing agent is preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass, per 100 parts by mass of the rubber component. Conventional vulcanization methods can be used, and the vulcanization temperature is preferably 120°C to 200°C, and more preferably 140°C to 180°C.

[0118] During vulcanization, a vulcanization accelerator may be used as needed. As the vulcanization accelerator, a conventionally known material 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 the vulcanization accelerator 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.

[0119] The rubber composition may contain various additives other than those described above, such as softeners, fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants, as long as they do not impair the object of this embodiment. Known softeners can be used as the other softeners. Specific examples of other fillers include 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.

[0120] [Tire] The modified diene polymer composition of the present embodiment is suitably used as a rubber composition for tires. That is, a tire of the present embodiment is made using the rubber composition.

[0121] The rubber composition for tires of this embodiment can be used in various tire parts such as treads, carcasses, sidewalls, beads, etc., of various tires such as fuel-efficient tires, all-season tires, high-performance tires, studless tires, etc., but is not limited to the following. In particular, the rubber composition for tires has excellent abrasion resistance and a balance between low hysteresis loss and wet skid resistance when vulcanized, and is therefore more preferably used for the treads of fuel-efficient tires and high-performance tires.

[0122] The present embodiment will be described in more detail with reference to the following specific examples and comparative examples, but the present embodiment is not limited to the following examples and comparative examples as long as the gist of the present embodiment is not exceeded. Various physical properties in the examples and comparative examples described below were measured by the methods shown below.

[0123] (Physical Property 1) Bound Styrene Amount

[0043] 100 mg of a modified conjugated diene polymer was used as a sample, and the sample was dissolved in chloroform to prepare a measurement sample. The amount of bound styrene (mass%) relative to 100 mass% of the modified conjugated diene polymer was measured based on the amount of absorption of ultraviolet light by the phenyl group of styrene (near 254 nm) (using a spectrophotometer "UV-2450" manufactured by Shimadzu Corporation).

[0124] (Physical Property 2) Microstructure of Butadiene Moiety (1,2-Vinyl Bond Amount) 50 mg of the modified conjugated diene polymer was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. Using a solution cell, the infrared spectrum was measured in the range of 600 to 1000 cm-1, and the microstructure of the butadiene moiety, i.e., the 1,2-vinyl bond amount (mol%), was determined from the absorbance at a predetermined wavenumber according to the calculation formula of the Hampton method (the method described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)) (using a Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation).

[0125] (Physical Property 3) Molecular Weight Measurement Condition 1: A conjugated diene polymer or a modified conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC measurement device (trade name "HLC-8320GPC" manufactured by Tosoh Corporation) in which three columns packed with polystyrene gel were connected together, and an RI detector (trade name "HLC8020" manufactured by Tosoh Corporation). Based on a calibration curve obtained using standard polystyrene, the weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw / Mn), and peak top molecular weight (Mp) of the modified conjugated diene polymer were determined. １ ) and the peak top molecular weight of the conjugated diene polymer (Mp ２ ) and its ratio (Mp １ / Mp ２ ) and molecular weight 200 × 10４ Above 500 x 10 ４ The following ratios and were determined. The eluent used was THF (tetrahydrofuran) containing 5 mmol / L triethylamine. Three columns, manufactured by Tosoh Corporation under the trade name "TSKgel SuperMultipore HZ-H," were connected, with a Tosoh Corporation under the trade name "TSKguardcolumn SuperMP(HZ)-H" connected in front of them as a guard column. 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 the GPC measurement device and measured under conditions of an oven temperature of 40°C and a THF flow rate of 0.35 mL / min. Among the various samples measured under the above measurement condition 1, samples with a molecular weight distribution (Mw / Mn) value of less than 1.6 were remeasured under the following measurement condition 2. For samples measured under measurement condition 1 and whose molecular weight distribution value was 1.6 or greater, the results measured under measurement condition 1 are shown in Tables 1 and 2.

[0126] Measurement condition 2: A conjugated diene polymer or a modified conjugated diene polymer was used as a sample. A chromatogram was measured using a GPC measuring device in which three columns packed with polystyrene gel were connected, and the weight average molecular weight (Mw), number average molecular weight (Mn), and peak top molecular weight (Mp) of the modified conjugated diene polymer were calculated based on a calibration curve using standard polystyrene. １ ) and the peak top molecular weight of the conjugated diene polymer (Mp ２ ) and its ratio (Mp １ / Mp ２ ) and molecular weight 200 × 10 ４ Above 500 x 10 ４The following ratios were determined. The eluent used was THF containing 5 mmol / L triethylamine. The columns used were a guard column manufactured by Tosoh Corporation under the trade name "TSKguard column Super H-H," and columns manufactured by Tosoh Corporation under the trade names "TSKgel Super H5000," "TSKgel Super H6000," and "TSKgel Super H7000." An RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020") was used under conditions of an oven temperature of 40°C and a THF flow rate of 0.6 mL / min. 10 mg of the sample to be measured was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into the GPC measurement device and measured. For samples measured under measurement condition 1 and whose molecular weight distribution value was less than 1.6, the results of measurement under measurement condition 2 are shown in Tables 1 and 2.

[0127] The peak top molecular weight (Mp １ and Mp ２ ) was determined under both measurement conditions 1 and 2 as follows. In the GPC curve obtained by measurement, the peak detected as the highest molecular weight component was selected. For the selected peak, the molecular weight corresponding to the maximum value of the peak was calculated and taken as the peak top molecular weight. In addition, the above-mentioned molecular weight of 200 × 10 ４ Above 500 x 10 ４ The following ratios are determined based on the molecular weight of 500×10 from the integral molecular weight distribution curve under both measurement conditions 1 and 2. ４ The molecular weight is 200 x 10 based on the percentage of the whole ４ This was calculated by subtracting the percentage of those under 100.

[0128] (Physical Property 4) Shrinkage Factor (g') Using a modified conjugated diene polymer as a sample, a GPC measurement apparatus (trade name "GPCmax VE-2001" manufactured by Malvern) equipped with three connected columns packed with polystyrene gel was used to measure the molecular weight using three detectors connected in this order: a light scattering detector, an RI detector, and a viscometer (trade name "TDA305" manufactured by Malvern). Based on standard polystyrene, the absolute molecular weight was determined from the results obtained by the light scattering detector and the RI detector, and the intrinsic viscosity was determined from the results obtained by the RI detector and the viscometer. The linear polymer was assumed to have an intrinsic viscosity [η] = -3.883 M0.771, and the shrinkage factor (g') was calculated as the ratio of intrinsic viscosities corresponding to each molecular weight. THF containing 5 mmol / L triethylamine was used as the eluent. The columns used were "TSKgel G4000HXL," "TSKgel G5000HXL," and "TSKgel G6000HXL" manufactured by Tosoh Corporation. 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 the GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 1 mL / min.

[0129] (Physical Property 5) Polymer Mooney Viscosity Using a conjugated diene polymer or modified conjugated diene polymer as a sample, the Mooney viscosity was measured using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) in accordance with JIS K6300 using an L-shaped rotor. The measurement temperature was 110°C when the sample was a conjugated diene polymer, and 100°C when the sample was a modified conjugated diene polymer. First, the sample was preheated at the test temperature for 1 minute, and then the rotor was rotated at 2 rpm. The torque was measured after 4 minutes to determine the Mooney viscosity (ML （１＋４） )

[0130] (Physical Property 6) Glass Transition Temperature (Tg) Using a modified conjugated diene polymer as a sample, a DSC curve was recorded in accordance with ISO 22768:2006 using a differential scanning calorimeter "DSC3200S" manufactured by Mac Science, Inc., while raising the temperature from -100°C at 20°C / min under a helium flow of 50 mL / min, and the peak top (inflection point) of the DSC differential curve was taken as the glass transition temperature.

[0131] (Physical Property 7) Modification Ratio The modified conjugated diene polymer was used as a sample, and the property of the modified basic polymer component being adsorbed onto a GPC column packed with silica gel was utilized for measurement. The amount of adsorption onto the silica column was measured by subtracting the chromatogram of a sample solution containing the sample and a low molecular weight internal standard polystyrene measured on a polystyrene column from that measured on a silica column, thereby determining the modification ratio. Specifically, this is as shown below. Furthermore, measurements were performed under Measurement Condition 1 of (Physical Property 3) above. For samples whose molecular weight distribution was 1.6 or greater, measurements were performed under Measurement Condition 3 below. For samples whose molecular weight distribution was less than 1.6, measurements were performed under Measurement Condition 4 below. The results are shown in Tables 1 and 2.

[0132] Preparation of sample solution: 10 mg of sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare a sample solution. GPC measurement conditions using a polystyrene column (measurement conditions 3): Using a Tosoh Corporation product name "HLC-8320GPC", 5 mmol / L of triethylamine-containing THF was used as the 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. Three columns, Tosoh Corporation product name "TSKgel SuperMultiporeHZ-H", were connected, and a Tosoh Corporation product name "TSKguardcolumn SuperMP(HZ)-H" was connected as a guard column in front of them.

[0133] Measurement condition 4: THF containing 5 mmol / L triethylamine was used as the eluent, and 20 μL of the sample solution was injected into the device and measured. The columns used were a guard column manufactured by Tosoh Corporation under the trade name "TSKguard column Super H-H," and columns manufactured by Tosoh Corporation under the trade names "TSKgel Super H5000," "TSKgel Super H6000," and "TSKgel Super H7000." A chromatogram was obtained using an RI detector (Tosoh Corporation HLC8020) at a column oven temperature of 40 °C and a THF flow rate of 0.6 mL / min.

[0134] GPC measurement conditions using a silica-based column: Tosoh Corporation's product name "HLC-8320GPC" was used, THF was used as the eluent, 50 μL of the sample solution was injected into the device, 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 0.5 ml / min. The columns were connected and used with product names "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S", and a guard column "DIOL 4.6 × 12.5 mm 5 micron" was connected to the front stage.

[0135] Calculation method for modification rate: The total peak area of ​​the chromatogram using a polystyrene 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 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 x P3) / (P1 x P4)] x 100 (where P1 + P2 = P3 + P4 = 100)

[0136] (Physical Property 8) Presence or Absence of Nitrogen Atoms Measurements similar to those in (Physical Property 7) were carried out, and when the calculated modification rate was 10% or more, it was determined that a nitrogen atom was present. This confirmed that the modified conjugated diene polymers of Examples 1 to 9 and Comparative Examples 2 and 3 contained nitrogen atoms, and that the modified conjugated diene polymer of Comparative Example 1 did not contain nitrogen atoms.

[0137] (Physical Property 9) Presence or Absence of Silicon Atoms 0.5 g of a modified conjugated diene polymer was used as a sample and measured using an ultraviolet-visible spectrophotometer (trade name "UV-1800" manufactured by Shimadzu Corporation) in accordance with JIS K 0101 44.3.1, and quantified by molybdenum blue absorptiometry. When silicon atoms were detected (detection limit 10 ppm by mass), it was determined that the polymer contained silicon atoms. This confirmed that the modified conjugated diene polymers of Examples 1 to 9 and Comparative Examples 1 to 3 contained silicon atoms.

[0138] Example 1 Modified Conjugated Diene Polymer (Sample 1) A tank-type pressure vessel 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, was used as the polymerization reactor. 1,3-butadiene, from which moisture had been removed in advance, was mixed at 17.9 g / min, styrene at 9.8 g / min, and n-hexane at 145.3 g / min. In a static mixer installed midway through the piping supplying this mixed solution to the inlet of the reactor, n-butyllithium for inactivating remaining impurities was added at 0.104 mmol / min, mixed, and then continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance at a rate of 0.0194 g / min and n-butyllithium as a polymerization initiator at a rate of 0.255 mmol / min were fed into the bottom of the polymerization reactor, which was being vigorously mixed with a stirrer, and the polymerization reaction was continued continuously. The temperature was controlled so that the temperature of the polymer solution at the top outlet of the reactor was 75°C. When the polymerization was sufficiently stabilized, a small amount of the polymer solution before the addition of the coupling agent was withdrawn from the top outlet of the reactor, and an antioxidant (BHT) was added in an amount of 0.2 g per 100 g of polymer, followed by removal of the solvent. The Mooney viscosity at 110°C and various molecular weights were measured. Other physical properties are also shown in Table 1.

[0139] Next, to the polymer solution flowing out of the reactor outlet, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine (abbreviated as "A" in the table), diluted to 2.74 mmol / L, was continuously added as a coupling agent at a rate of 0.0425 mmol / min (n-hexane solution containing 5.2 ppm of water), and the polymer solution to which the coupling agent had been added was mixed by passing through a static mixer to undergo a coupling reaction. At this time, it took 4.8 minutes for the coupling agent to be added to the polymer solution flowing out of the reactor outlet, the temperature was 68°C, and the difference between the temperature in the polymerization step and the temperature before the addition of the modifier was 7°C. To the polymer solution that had undergone the coupling reaction, an antioxidant (BHT) was continuously added at 0.055 g / min (n-hexane solution) to give 0.2 g per 100 g of polymer, and the coupling reaction was terminated. Simultaneously with the antioxidant, 37.5 g of oil (JOMO Process NC140, manufactured by JX Nippon Oil & Energy Corporation) was continuously added per 100 g of polymer, and the mixture was mixed in a static mixer. The solvent was removed by steam stripping to obtain a modified conjugated diene polymer (Sample 1). The physical properties of Sample 1 are shown in Table 1.

[0140] (Example 2) Modified conjugated diene polymer (sample 2) A modified conjugated diene polymer (sample 2) was obtained in the same manner as in Example 1, except that the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to tris(3-trimethoxysilylpropyl)amine (abbreviated as "B" in the table). The physical properties of sample 2 are shown in Table 1.

[0141] (Example 3) Modified conjugated diene polymer (sample 3) A modified conjugated diene polymer (sample 3) was obtained in the same manner as in Example 1, except that the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to tris(3-triethoxysilylpropyl)amine (abbreviated as "C" in the table). The physical properties of sample 3 are shown in Table 1.

[0142] Example 4 Modified Conjugated Diene Polymer (Sample 4) A modified conjugated diene polymer (Sample 4) was obtained in the same manner as in Example 1, except that the addition rate of the treated n-butyllithium was 0.117 mmol / min, the addition rate of the polymerized n-butyllithium was 0.242 mmol / min, the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine (abbreviated as "D" in the table), and the addition rate of the coupling agent was 0.0302 mmol / min. The physical properties of Sample 4 are shown in Table 1.

[0143] Example 5 Modified Conjugated Diene Polymer (Sample 5) A modified conjugated diene polymer (Sample 5) was obtained in the same manner as in Example 1, except that the addition rate of the treated n-butyllithium was 0.108 mmol / min, the addition rate of the polymerized n-butyllithium was 0.251 mmol / min, the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine (abbreviated as "E" in the table), and the addition rate of the coupling agent was 0.0359 mmol / min. The physical properties of Sample 5 are shown in Table 1.

[0144] Example 6 Modified Conjugated Diene Polymer (Sample 6) A modified conjugated diene polymer (Sample 6) was obtained in the same manner as in Example 1, except that the addition rate of the treated n-butyllithium was 0.117 mmol / min, the addition rate of the polymerized n-butyllithium was 0.242 mmol / min, the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to tetrakis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-propanediamine (abbreviated as "F" in the table), and the addition rate of the coupling agent was 0.0302 mmol / min. The physical properties of Sample 6 are shown in Table 1.

[0145] Example 7 Modified Conjugated Diene Polymer (Sample 7) A modified conjugated diene polymer (Sample 7) was obtained in the same manner as in Example 1, except that the addition rate of the treated n-butyllithium was 0.117 mmol / min, the addition rate of the polymerized n-butyllithium was 0.242 mmol / min, the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine (abbreviated as "G" in the table), and the addition rate of the coupling agent was 0.0302 mmol / min. The physical properties of Sample 7 are shown in Table 1.

[0146] Example 8 Modified Conjugated Diene Polymer (Sample 8) A modified conjugated diene polymer (Sample 8) was obtained in the same manner as in Example 1, except that the addition rate of the treated n-butyllithium was 0.117 mmol / min, the addition rate of the polymerized n-butyllithium was 0.242 mmol / min, the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to tetrakis(3-trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane (abbreviated as "H" in the table), and the addition rate of the coupling agent was 0.0302 mmol / min. The physical properties of Sample 8 are shown in Table 2.

[0147] Example 9 Modified Conjugated Diene Polymer (Sample 9) A modified conjugated diene polymer (Sample 9) was obtained in the same manner as in Example 1, except that the addition rate of the treating n-butyllithium was 0.124 mmol / min, the addition rate of the polymerized n-butyllithium was 0.286 mmol / min, the polar substance 2,2-bis(2-oxolanyl)propane was 0.0265 g / min, the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to tris(3-trimethoxysilylpropyl)amine (B), and the addition rate of the coupling agent was 0.0477 mmol / min. The physical properties of Sample 9 are shown in Table 2.

[0148] Comparative Example 1 Modified Conjugated Diene Polymer (Sample 10) A modified conjugated diene polymer (Sample 10) was obtained in the same manner as in Example 1, except that the addition rate of the treated n-butyllithium was 0.114 mmol / min, the addition rate of the polymerized n-butyllithium was 0.248 mmol / min, the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to bis(trimethoxysilyl)ethane (abbreviated as "I" in the table), and the addition rate of the coupling agent was 0.0620 mmol / min. The physical properties of Sample 11 are shown in Table 2.

[0149] Comparative Example 2 Modified Conjugated Diene Polymer (Sample 11) A modified conjugated diene polymer (Sample 11) was obtained in the same manner as in Example 1, except that the addition rate of the treating n-butyllithium was 0.114 mmol / min, the addition rate of the polymerized n-butyllithium was 0.248 mmol / min, the coupling agent was changed from bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine to bis(3-trimethoxysilylpropyl)methylamine (abbreviated as "J" in the table), and the addition rate of the coupling agent was 0.0620 mmol / min. The physical properties of Sample 11 are shown in Table 2.

[0150] Comparative Example 3: Branched Modified Diene Polymer (Sample 12) A 30 L temperature-controllable autoclave equipped with a stirrer and jacket was used as a reactor. 17,200 g of normal hexane, 1,022 g of styrene, 1,778 g of 1,3-butadiene, and 1.26 g of 2,2-bis(2-oxolanyl)propane as a polar substance, all of which had been previously purified, were placed in the reactor. When the temperature inside the reactor reached 48°C, 17.0 mmol of polymerization initiator n-butyllithium was added to initiate polymerization. Immediately after the start of polymerization, the temperature inside the reactor rose, reaching a peak (83°C). Once a decrease in temperature was confirmed, 3.48 mmol of coupling agent bis(3-trimethoxysilylpropyl)methylamine (J) was added, and the mixture was stirred for an additional 10 minutes. 17.0 mmol of ethanol was added as a polymerization terminator to terminate the reaction, yielding a polymer solution containing a modified conjugated diene polymer. To the resulting polymer solution, 5.6 g of an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer, and the solvent was then removed by steam stripping to obtain a branched modified diene polymer (Sample 12). The physical properties of Sample 12 are shown in Table 2.

[0151]

[0152]

[0153] The "degree of branching" shown in Tables 1 and 2 is the number of branches estimated from the number of functional groups of the coupling agent and the amount added, and can also be confirmed from the value of the shrinkage factor. The "number of SiOR residues" shown in Tables 1 and 2 is the value obtained by subtracting the number of SiOR groups reduced by the reaction from the total number of SiOR groups per molecule of the coupling agent. The rubber coupled with the coupling agent (I) used in Comparative Example 1 was not adsorbed by the silica column, and the modification rate could not be measured.

[0154] (Examples 10 to 18 and Comparative Examples 4 to 6) Using Samples 1 to 12 shown in Tables 1 and 2 as raw rubbers, rubber compositions containing each raw rubber were obtained according to the formulations shown below. Modified conjugated diene polymer (Samples 1 to 12): 100 parts by mass (oil excluded) Silica 1 (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa, nitrogen adsorption specific surface area 170 m 2 / g): 50.0 parts by mass Silica 2 (manufactured by Rhodia under the trade name "Zeosil Premium 200MP" with a nitrogen adsorption specific surface area of ​​220 m 2 / g): 25.0 parts by mass Carbon black (trade name "SEAT KH (N339)" manufactured by Tokai Carbon Co., Ltd.): 5.0 parts by mass Silane coupling agent (trade name "Si75" manufactured by Evonik Degussa, bis(triethoxysilylpropyl) disulfide): 6.0 parts by mass S-RAE oil (trade name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation): 37.5 parts by mass Zinc oxide: 2.5 parts by mass Stearic acid: 1.0 part by mass Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass Sulfur: 2.2 parts by mass Vulcanization accelerator 1 (N-cyclohexyl-2-benzothiazylsulfinamide): 1.7 parts by mass Vulcanization accelerator 2 (diphenylguanidine): 2.0 parts by mass Total: 239.4 parts by mass

[0155] The above materials were kneaded by the following method to obtain rubber compositions. Using an internal kneader (0.3 L capacity) equipped with a temperature control device, the raw rubber (samples 1 to 12), fillers (silica 1, silica 2, 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 155 to 160°C.

[0156] Next, in the second stage of mixing, the compound obtained above was cooled to room temperature, and then an antioxidant was added. The compound was then mixed again to improve dispersion of the silica. Again, the temperature of the mixer was controlled to 155-160°C to adjust the discharge temperature of the compound to 155-160°C. 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 compositions before and after vulcanization were evaluated. Specifically, the evaluations were performed using the following methods. The results are shown in Tables 3 and 4.

[0157] (Evaluation 1) Mooney Viscosity of Blend The blend obtained above after the second stage kneading but before the third stage kneading was used as a sample, and after preheating at 130°C for 1 minute, the rotor was rotated at 2 revolutions per minute for 4 minutes, and the viscosity was measured using a Mooney viscometer in accordance with JIS K6300-1. The result of Comparative Example 4 was set to 100 and the results were indexed. A smaller index indicates better processability.

[0158] (Evaluation 2) Viscoelastic parameters Viscoelastic parameters were measured in torsion mode using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific. Each measurement value was indexed, with the result for the rubber composition of Comparative Example 4 being set at 100. 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 indicates better wet grip performance. Furthermore, tan δ measured at 50°C, a frequency of 10 Hz, and a strain of 3% was used as an index of fuel economy. A smaller index indicates better fuel economy.

[0159] (Evaluation 3) Tensile strength and tensile elongation Tensile strength and tensile elongation were measured in accordance with the tensile testing method of JIS K6251, and indexed based on the result of Comparative Example 4 being 100. A larger index indicates better tensile strength and tensile elongation.

[0160] (Evaluation 4) 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 4 was indexed as 100. A larger index indicates better abrasion resistance.

[0161]

[0162]

[0163] As shown in Tables 3 and 4, it was confirmed that the modified conjugated diene polymers of Examples 10 to 18, when vulcanized, had a better balance of wet grip properties and fuel economy, and also had better abrasion resistance, compared to the modified conjugated diene polymers of Comparative Examples 4 to 6. It was also confirmed that the compounds had low Mooney viscosities when vulcanized, and exhibited good processability. It was also confirmed that the vulcanized products had sufficient breaking strength for practical use.

[0164] This application is based on a Japanese patent application (Patent Application No. 2015-031098) filed with the Japan Patent Office on February 19, 2015, the contents of which are incorporated herein by reference.

[0165] The modified conjugated diene polymer according to the present invention has industrial applicability in fields such as tire treads, interior and exterior parts of automobiles, vibration-proof rubber, belts, footwear, foams, and various industrial goods.

Claims

19 / 05 / 25661. Conjugated diene-based polymers isolated from solvents with a weight-average molecular weight of 20x10⁴ or more and 300x10⁴ or less, and at least one tandem residue and conjugated diene-based polymer chains bonded to the tandem residue, comprising: conjugated diene-based polymers with molecular weights of 200x10⁴ or more and 500x10⁴ or less in amounts of 0.25% by mass or more and 30% by mass or less relative to the total amount of conjugated diene-based polymers, where the shrinkage factor (g') is less than 0.64;