Rubbery polymer and rubber composition comprising the same

Abstract

To provide a rubbery polymer which can enhance material strength near a temperature zone corresponding to wet grip, while exhibiting superior wear resistance and wet grip, and a rubber composition comprising the same.SOLUTION: A rubbery polymer comprises two or more structural units selected from the group consisting of structural units represented by specific formulae (1) to (4), wherein the structural units include at least a structural unit represented by formula (2), wherein the weight-average molecular weight is 100,000 or more as measured by gel permeation chromatography (GPC), and wherein the full width at half maximum (FWHM) value is 20°C or more for a tanδ peak observed in the temperature range of -100°C to 100°C in a temperature-dependent tanδ graph derived from dynamic viscoelastic analysis through a rheometry system (ADVANCED RHEOMETRIC EXPANSION SYSTEM, ARES).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a rubber-like polymer and a rubber composition containing the same.

Background Art

[0002] In recent years, with the demand for lower fuel consumption in automobiles, as a rubber material for tires, a conjugated diene polymer having low rolling resistance, excellent abrasion resistance and tensile properties, and also having adjustment stability represented by wet skid resistance has been demanded.

[0003] As basic functions required for an automobile tire tread, there are braking performance and abrasion resistance on the road surface. As a rubber material used for a tire tread, a rubber material having excellent braking performance (wet grip performance) not only on a dry road surface but also on a wet road surface and being wear-resistant and long-lasting is required.

[0004] Conventionally, in order to improve the abrasion resistance performance, a technique for lowering the glass transition temperature of a rubber material has been proposed in order to lower the glass transition temperature of a rubber composition.

[0005] On the other hand, a method for increasing the glass transition temperature of a rubber composition is known in order to improve the wet grip performance, and a technique for increasing the glass transition temperature of a rubber material has been proposed in order to increase the glass transition temperature of a rubber composition.

[0006]

[0007] For example, Patent Document 1 discloses a conjugated diene polymer having a difference between a glass transition start temperature and a glass transition end temperature, and proposes an improvement in the balance between wet grip performance and abrasion resistance.

Prior Art Documents

Patent Document

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, when braking on an actually wet road surface, a large stress is applied to the rubber material due to the friction with the road surface, and a part of the rubber material tends to chip off from the tire. That is, in the environment during braking on a wet road surface, further strength as a rubber material is also required.

[0010] Therefore, an object of the present invention is to provide a rubber-like polymer that can exhibit good abrasion resistance and wet grip while further increasing the material strength in the temperature range corresponding to wet grip, and a rubber composition containing the same.

Means for Solving the Problems

[0011] As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have found that a rubber-like polymer satisfying specific requirements can exhibit good abrasion resistance and wet grip while further increasing the material strength in the temperature range corresponding to wet grip, and can prevent chipping from the tire, for example, and have completed the present invention.

[0012] That is, the present invention is as follows. [1] It contains two or more structural units selected from the group consisting of each structural unit represented by the following formulas (1) to (4), and among the respective structural units, it contains at least the structural unit represented by formula (2), The weight average molecular weight measured by gel permeation chromatography (GPC) is 100,000 or more, In the tanδ graph by temperature obtained from the dynamic viscoelasticity analysis using a rheometry system (ADVANCED RHEOMETRIC EXPANSION SYSTEM, ARES) measured under the following conditions, the full width at half maximum (FWHM) value of the tanδ peak appearing in the temperature range of -100°C to 100°C is 20°C or more. Rubbery polymer. [Chemistry] [The rheometry system uses a sample of the rubbery polymer and measures in torsion mode under the conditions of a frequency of 10 Hz, a strain of 0.5%, and a heating rate of 5°C / min using a dynamic mechanical analyzer.] [2] When the total content of each structural unit represented by the above formulas (1) to (4) is 100 mol%, The total content of the content C1 of the structure represented by the above formula (1) and the content C2 of the structure represented by the above formula (2) is 15 mol% or more and 50 mol% or less, The content C3 of the structure represented by the above formula (3) is 10 mol% or more and 30 mol% or less, The rubbery polymer according to [1], wherein the content C4 of the structure represented by the above formula (4) is 35 mol% or more and 65 mol% or less. [3] The rubbery polymer according to [1] or [2], wherein the full width at half maximum (FWHM) value of the tanδ peak is 20°C or more and 80°C or less. [4] The rubbery polymer according to any one of [1] to [3], wherein the tanδ peak appears in the temperature range of -50°C to 20°C. [5] The rubbery polymer according to any one of [1] to [4], wherein the content S of the aromatic vinyl monomer unit is 25% by mass or more and 45% by mass or less. [6] When the total content of each structural unit represented by the above formulas (1) to (4) is 100 mol%, The total content of the content C1 of the structure represented by the formula (1) and the content C2 of the structure represented by the formula (2) is 15 mol% or more and 30 mol% or less, the content C3 of the structure represented by the formula (3) is 14 mol% or more and 25 mol% or less, and the content C4 of the structure represented by the formula (4) is 45 mol% or more and 60 mol% or less. The rubber-like polymer according to any one of [1] to [5]. [7] The rubber-like polymer according to any one of [1] to [6], wherein the nitrogen atom content is 30 ppm or more based on the total mass of the rubber-like polymer. [8] The rubber-like polymer is a modified rubber-like polymer modified with a modifier. The rubber-like polymer according to any one of [1] to [7], wherein the modifier is an alkoxysilane compound containing a nitrogen-containing functional group. [9] A rubber composition comprising 100 parts by mass of the rubber-like polymer according to any one of [1] to [8] and 0.1 part by mass or more and 200 parts by mass or less of a filler.

[10] The rubber composition according to [9], wherein the filler is a silica-based filler and / or a carbon black-based filler.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a rubber-like polymer that exhibits good abrasion resistance and wet grip, and further enhances the material strength in the vicinity of the temperature range corresponding to the wet grip, and a rubber composition containing the same.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the following embodiments are examples for explaining the present invention, and the present invention is not limited thereto. That is, the present invention can be arbitrarily modified and implemented without departing from the gist thereof. In this specification, when expressing numerical values or physical property values with "~" sandwiched before and after, the values before and after are used as including those values.

[0015] In addition, in this specification, "monomer" means a compound before polymerization, and "monomer unit" means a structural unit constituting a polymer.

[0016] [Rubbery polymer] The rubbery polymer of the present embodiment contains two or more structural units selected from the group consisting of each structural unit represented by the following formulas (1) to (4), and among these structural units, at least contains the structural unit represented by formula (2). The weight average molecular weight measured by gel permeation chromatography (GPC) is 100,000 or more. In the tanδ graph by temperature obtained from the dynamic viscoelasticity analysis using a rheometry system (ADVANCED RHEOMETRIC EXPANSION SYSTEM, ARES) measured under the following conditions, the full width at half maximum (FWHM) value of the tanδ peak (hereinafter also referred to as "the full width at half maximum (FWHM) value of the tanδ peak") appearing in the temperature range of -100°C to 100°C is 20°C or more. [Chemical formula] [The rheometry system uses a sample of the rubbery polymer and measures in torsion mode under the conditions of a frequency of 10 Hz, a strain of 0.5%, and a heating rate of 5°C / min using a dynamic mechanical analyzer.]

[0017] By having such characteristics, the rubbery polymer of the present embodiment can exhibit good abrasion resistance and wet grip, and can further enhance the material strength in the vicinity of the temperature region corresponding to the wet grip.

[0018] When the total content of each structural unit represented by the above formulas (1) to (4) is 100 mol%, the total content of the content C1 of the structure represented by the above formula (1) (hereinafter also referred to as "structural formula (1)") and the content C2 of the structure represented by the above formula (2) (hereinafter also referred to as "structural formula (2)") is preferably 15 mol% or more and 50 mol% or less, the content C3 of the structure represented by the above formula (3) (hereinafter also referred to as "structural formula (3)") is preferably 10 mol% or more and 30 mol% or less, and the content C4 of the structure represented by the above formula (4) (hereinafter also referred to as "structural formula (4)") is preferably 35 mol% or more and 65 mol% or less.

[0019] In the rubber-like polymer of the present embodiment, the structural unit represented by the structural formula (1) corresponds to, for example, a 1,2-vinyl bond unit of a conjugated diene compound, but the raw material is not particularly limited as long as it is the same as the structural unit represented by the structural formula (1).

[0020] When the total content of each structural unit represented by the above formulas (1) to (4) is 100 mol%, the content C1 of the structure represented by the structural formula (1) (hereinafter simply referred to as "C1") is preferably 0.0 mol% or more and 3.0 mol% or less, more preferably 0.0 mol% or more and 2.8 mol% or less, and even more preferably 0.0 mol% or more and 2.6 mol% or less. When C1 is within the above-mentioned preferred range, the vulcanizate tends to be excellent in breaking strength, breaking elongation, and ozone resistance.

[0021] In the rubber-like polymer of the present embodiment, the structural unit represented by the structural formula (2) corresponds to, for example, a hydrogenated 1,2-vinyl bond unit of a conjugated diene compound, but the raw material is not particularly limited as long as it is the same as the structural unit represented by the structural formula (2).

[0022] When the total content of each structural unit represented by the structural formulas (1) to (4) is 100 mol%, the content C2 of the structure represented by the structural formula (2) (hereinafter, also simply referred to as "C2") is preferably 15.0 mol% or more and 50.0 mol% or less, more preferably 16.0 mol% or more and 45.0 mol% or less, still more preferably 17.0 mol% or more and 40.0 mol% or less, and particularly preferably 18.0 mol% or more and 35.0 mol% or less. When C2 is within the above-mentioned preferred range, the vulcanizate tends to be excellent in breaking strength and elongation at break.

[0023] In the rubber-like polymer of the present embodiment, the structural unit represented by the structural formula (3) corresponds to, for example, the 1,4-cis bond unit and 1,4-trans bond unit of a conjugated diene compound, but the raw material is not particularly limited as long as it is the same as the structural unit represented by the formula (3).

[0024] When the total content of each structural unit represented by the structural formulas (1) to (4) is 100 mol%, the content C3 of the structure represented by the structural formula (3) (hereinafter, also simply referred to as "C3") is preferably 10 mol% or more and 30 mol% or less, more preferably 11 mol% or more and 29 mol% or less, still more preferably 12 mol% or more and 28 mol% or less, even more preferably 13 mol% or more and 27 mol% or less, and particularly preferably 14 mol% or more and 25 mol% or less. When C3 is within the above-mentioned preferred range, the crosslinkability tends to be good when forming a rubber composition described later.

[0025] Here, the contents of the 1,4-cis bond and 1,4-trans bond can be measured using 13 C-NMR. Specifically, it can be measured by the method described in the examples below.

[0026] Also, in the structural unit represented by the formula (3), the contents of the 1,4-cis bond and 1,4-trans bond can be controlled within the above numerical ranges by adjusting the type of polymerization initiator, the type of polar compound, and the addition amount, which will be described later.

[0027] In the rubber-like polymer of the present embodiment, the structural unit represented by the structural formula (4) corresponds to, for example, an ethylene structure, or a hydrogenated product of a 1,4-cis bond unit and a 1,4-trans bond unit of a conjugated diene compound. However, as long as it is the same as the structural unit represented by the formula (4), the raw material thereof is not particularly limited.

[0028] When the total content of each structural unit represented by the structural formulas (1) to (4) is 100 mol%, the content C4 of the structure represented by the structural formula (4) (hereinafter, also simply referred to as "C4") is preferably 35 mol% or more and 65 mol% or less, more preferably 40 mol% or more and 64 mol% or less, still more preferably 42 mol% or more and 63 mol% or less, even more preferably 43 mol% or more and 62 mol% or less, and particularly preferably 45 mol% or more and 60 mol% or less. When C4 is within the above-mentioned preferred range, orientation described later is likely to occur, so that the wet grip property is excellent, and in addition, it behaves pseudo-like a filler in a low-temperature environment corresponding to wet grip, so that the material strength tends to be excellent.

[0029] When the total content of each structural unit represented by the structural formulas (1) to (4) is 100 mol%, the total content of the content C1 of the structure represented by the structural formula (1) and the content C2 of the structure represented by the structural formula (2) is preferably 15 mol% or more and 50 mol% or less, more preferably 15 mol% or more and 45 mol% or less, still more preferably 15 mol% or more and 40 mol% or less, and particularly preferably 15 mol% or more and 30 mol% or less. When the total content of C1 and C2 is within the above-mentioned preferred range, the vulcanizate tends to be excellent in breaking strength, breaking elongation, and ozone resistance.

[0030] In the present embodiment, the contents C1 to C4 of each structural unit represented by the structural formulas (1) to (4) can be measured by 1 1H-NMR described in the examples below.

[0031] In the rubber-like polymer of the present embodiment, the method for controlling the contents C1 to C4 of the respective structural units represented by the structural formulas (1) to (4) within the preferred ranges is not particularly limited. For example, the amount of the polar substance added during polymerization or the polymerization temperature can be used to control the amount of 1,2-vinyl bonds in the copolymer before hydrogenation, or the hydrogenation rate can be controlled.

[0032] (Hydrogenation reaction) The rubber-like polymer of the present embodiment may be a hydrogenated copolymer. In this case, in the rubber-like polymer, for example, by hydrogenating (hydrogenating) the conjugated diene portion described later, a hydrogenated copolymer can be obtained.

[0033] The method for hydrogenating the conjugated diene portion of the rubber-like polymer is not particularly limited, and known methods can be used. For example, as described in WO96 / 05250, JP2000-053706A, WO2003 / 085010, WO2019 / 151126, WO2019 / 151127, WO2002 / 002663, WO2015 / 006179, a method of polymerizing a conjugated diene monomer by anionic polymerization under various additives and conditions, copolymerizing with other monomers as necessary, and then hydrogenating is preferably mentioned as a method.

[0034] The hydrogenation rate of the hydrogenated copolymer is the ratio (molar ratio) of the double bonds of the structure derived from the conjugated diene monomer unit that have become saturated bonds by the hydrogenation reaction, and can be represented by the following mathematical formula (A) using the contents C1 to C4 of the respective structural units represented by the structural formulas (1) to (4). Mathematical formula (A): 100*(C2 + C4) / (C1 + C2 + C3 + C4)

[0035] The hydrogenation reaction may be either a batch process, a continuous process, or a combination thereof. Here, when a continuous process is employed in the hydrogenation reaction, a distribution occurs in the hydrogenation rate in the resulting polymer, and as described later, structural non-uniformity occurs and the full width at half maximum (FWHM) value of the tanδ peak tends to broaden, which is preferable.

[0036] When the rubber-like polymer of the present embodiment is a hydrogenated copolymer, its hydrogenation rate is represented by the above formula (A), and the hydrogenation rate (hydrogenation ratio) of the structural unit derived from the conjugated diene compound (for example, butadiene) is preferably 55% or more and 98% or less, more preferably 60% or more and 95% or less, and still more preferably 65% or more and 90% or less.

[0037] The hydrogenation rate (hydrogenation ratio) can be controlled within the above numerical range by adjusting the hydrogen addition amount, reaction temperature, reaction time, type of catalyst, and catalyst addition amount. In particular, the hydrogenation rate of the structural unit derived from the conjugated diene compound can be controlled by the amount of hydrogen added to the structural unit derived from the conjugated diene compound.

[0038] The temperature of the hydrogenation reaction is not particularly limited, but is preferably 60 to 105°C, more preferably 70 to 100°C.

[0039] Note that the hydrogenation rate can be 1 measured by 1H-NMR.

[0040] Here, the contents C1 to C4 of the respective structural units represented by the structural formulas (1) to (4) preferably satisfy the following formula (B). Formula (B): 90(%) ≤ 100*C2 / (C1 + C2)

[0041] The above formula (B) corresponds to, for example, the hydrogenation rate of the 1,2-vinyl bond of the conjugated diene monomer.

[0042] From the viewpoint of suppressing gelation, the formula (B) is preferably 90% or more, more preferably 92% or more, and even more preferably 94% or more. The upper limit of the formula (B) is not particularly limited, but is preferably 100% or less, more preferably less than 100%, and even more preferably 99% or less.

[0043] The total content of the structure represented by the structural formula (1) and the content of the structure represented by the structural formula (2) is, for example, the content ratio of the 1,2-vinyl bond of the conjugated diene monomer and the butylene structure in which the 1,2-vinyl bond is hydrogenated, and corresponds to the amount of 1,2-vinyl bonds in the copolymer before hydrogenation.

[0044] The content of the 1,2-vinyl bond can be controlled by the polymerization temperature during polymerization and the addition amount of the polar compound described later. In addition, the amount of 1,2-vinyl bonds in the rubber-like polymer before hydrogenation 1 can be measured by H-NMR. Even when the rubber-like polymer after hydrogenation is used as a sample, the so-called vinyl bond amount and butylene bond amount are targeted 1 and the content of the 1,2-vinyl bond can be measured by H-NMR.

[0045] Each structural unit represented by the structural formulas (1) to (4) of the rubber-like polymer of the present embodiment is preferably a structural unit derived from a conjugated diene compound (hereinafter also referred to as "conjugated diene monomer") or a structural unit obtained by hydrogenating them.

[0046] The conjugated diene monomer is not particularly limited, and examples thereof include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, from the viewpoint of easy industrial availability, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. These may be used alone or in combination of two or more.

[0047] The weight average molecular weight (Mw) of the rubbery polymer of the present embodiment is 100,000 or more, preferably 120,000 or more and 1,000,000 or less, more preferably 150,000 or more and 900,000 or less, still more preferably 180,000 or more and 800,000 or less, and even more preferably 200,000 or more and 700,000 or less, from the viewpoint of achieving a good balance between tensile strength and processability.

[0048] Also, from the viewpoints of adhesion during production and moldability of the rubber bale, the weight average molecular weight (Mw) of the rubbery polymer of the present embodiment is preferably within the above-mentioned range.

[0049] The weight average molecular weight (Mw) can be controlled within the above numerical range, for example, by adjusting the amount of polymerization initiator used.

[0050] The weight average molecular weight (Mw) of the rubbery polymer of the present embodiment can be measured by gel permeation chromatography (hereinafter also referred to as "GPC"). Specifically, it can be measured by the method described in the examples below.

[0051] The glass transition temperature of the rubbery polymer of the present embodiment is not particularly limited, but from the viewpoint of wet grip performance, it is preferably -50°C or higher, more preferably -45°C or higher, and still more preferably -40°C or higher.

[0052] On the other hand, from the viewpoint of maintaining practically sufficient abrasion resistance, the glass transition temperature of the rubbery polymer of the present embodiment is preferably 20°C or lower, more preferably 15°C or lower, and particularly preferably 10°C or lower.

[0053] The glass transition temperature of the rubbery polymer can be controlled within the above range, for example, by adjusting the value of the above formula (A), the vinyl bond amount, the hydrogenation rate, etc., or by adjusting the content of the aromatic vinyl monomer unit described below.

[0054] Generally, the glass transition temperature of the rubber-like polymer tends to increase as the content of the aromatic vinyl monomer unit described later increases, and also tends to increase as the content of the structural unit represented by the structural formula (4) increases. On the other hand, in the case of the hydrogenated rubber-like polymer, the glass transition temperature tends to decrease as the proportion of hydrogenated 1,2-vinyl bonds increases.

[0055] When controlling the glass transition temperature of the rubber-like polymer to, for example, -50 °C or higher, the content of the aromatic vinyl monomer unit described later is preferably 25% by mass or more, the amount of 1,2-vinyl bonds is preferably 15 mol% or more and 40 mol% or less, and the hydrogenation rate is preferably 40% or more and 98% or less.

[0056] When controlling the glass transition temperature of the rubber-like polymer to, for example, -45 °C or higher, the content of the aromatic vinyl monomer unit described later is preferably 30% by mass or more, the amount of 1,2-vinyl bonds is preferably 15 mol% or more and 40 mol% or less, and the hydrogenation rate is preferably 60% or more and 98% or less.

[0057] When controlling the glass transition temperature of the rubber-like polymer to, for example, -40 °C or higher, the content of the aromatic vinyl monomer unit described later is preferably 35% by mass or more, the amount of 1,2-vinyl bonds is preferably 15 mol% or more and 40 mol% or less, and the hydrogenation rate is preferably 65% or more and 98% or less.

[0058] When the glass transition temperature of the rubber-like polymer is within the above preferable range, the rubber composition obtained using the rubber-like polymer tends to have an excellent balance between abrasion resistance and wet grip performance.

[0059] Regarding the glass transition temperature, in accordance with ISO 22768:2006, while flowing nitrogen at 50 mL / min, a differential scanning calorimetry curve (DSC curve) is recorded while raising the temperature from -100 °C at 10 °C / min, and the peak top (Inflection point) derived from the glass transition of the obtained DSC differential curve is taken as the glass transition temperature.

[0060] The rubber-like polymer of this embodiment is excellent in tensile properties and running resistance, and excellent in wet skid resistance and abrasion resistance by controlling the full width at half maximum (FWHM) value of the tanδ peak appearing in the temperature range of -100°C to 100°C to be 20°C or more in the tanδ graph by temperature obtained from dynamic viscoelasticity analysis using a rheometry system (ADVANCED RHEOMETRIC EXPANSION SYSTEM, ARES).

[0061] Here, the rheometry system uses a sample of the rubber-like polymer and measures in torsion mode under the conditions of a frequency of 10 Hz, a strain of 0.5%, and a heating rate of 5°C / min using a dynamic mechanical analyzer.

[0062] The glass transition temperature of the rubber-like polymer of this embodiment is highly correlated with the tanδ peak temperature in the tanδ graph by temperature obtained from dynamic viscoelasticity analysis using a rheometry system (ADVANCED RHEOMETRIC EXPANSION SYSTEM, ARES).

[0063] The rubber-like polymer of this embodiment has two or more structures selected from the group consisting of the structures represented by the above structural formulas (1) to (4), and in the tanδ graph by temperature obtained from dynamic viscoelasticity analysis compared with the conventional rubber-like polymer, the full width at half maximum (FWHM) value of the tanδ peak appearing in the temperature range of -100°C to 100°C tends to be wider.

[0064] The reason for this is not clear, but roughly classified by the structure of the rubber-like polymer, two types or a combination thereof can be considered: (i) cases due to the inhomogeneity of the structure and (ii) cases due to the orientation of the components of the above structural formula (4).

[0065] In the case where it is caused by structural non-uniformity as in (i), when the rubber-like polymer exhibits a uniform structure within the molecule, the glass transition start temperature and the glass transition end temperature are substantially the same as the glass transition temperature, and the full width at half maximum (FWHM) value of the tanδ peak tends not to exceed 20°C. However, the rubber-like polymer of the present embodiment has structural non-uniformity within the molecule, so that the full width at half maximum (FWHM) value of the tanδ peak spreads to 20°C or more, and it is excellent in wet skid resistance and abrasion resistance.

[0066] As a method for obtaining such a rubber-like polymer having non-uniformity, it is not particularly limited. For example, a rubber-like polymer having a full width at half maximum (FWHM) value of the tanδ peak of 20°C or more, or a copolymer of a rubber-like polymer and an aromatic vinyl compound is hydrogenated by the method described later, or when hydrogenating a rubber-like polymer or a copolymer of a rubber-like polymer and an aromatic vinyl compound, a distribution is given to the hydrogenation rate to generate the components of the structural formulas (1) to (4) having different glass transition temperatures within the same molecule. Such methods are conceivable.

[0067] On the other hand, in the case of (ii), even after reaching the glass transition point, since the movement of the molecules is restricted by the orientation of the component of the structural formula (4), the glass transition end temperature shifts to the high temperature side, and as a result, the full width at half maximum (FWHM) value of the tanδ peak is considered to widen.

[0068] Here, since the longer the length of the repeating unit of the component of the structural formula (4), the more remarkable the influence of the orientation appears, the full width at half maximum (FWHM) value of the tanδ peak tends to widen.

[0069] As a method for obtaining a rubber polymer in which the full width at half maximum (FWHM) value of the tanδ peak is wide due to the orientation of the component of the structural formula (4) as described above, it is not particularly limited. For example, a rubber-like polymer having a wide molecular weight distribution or a copolymer of a rubber-like polymer and an aromatic vinyl compound is hydrogenated to cause a distribution in the length of the structural formula (4), or the component ratio of the structural formula (4) is increased to increase the components that are oriented after reaching the glass transition point. Such methods are exemplified.

[0070] Furthermore, the rubber-like polymer of the present embodiment has higher strength as a rubber material than a rubber-like polymer showing an equivalent DSC curve in the temperature range corresponding to wet grip, and is less likely to chip when applied to a tire tread.

[0071] The reason for this is not clear, but since the rubber-like polymer of the present embodiment contains the component of the structural formula (4) having orientation in the molecule, the relaxation of the component whose molecular motion is restricted by the orientation contributes to the DSC curve. Since the component restricting the molecular motion caused by such orientation behaves as a filler, it is considered that, as a result, it shows higher strength than a rubber-like polymer having an equivalent DSC curve in the vicinity of the temperature corresponding to wet grip.

[0072] When the half-value width (FWHM) value of the tanδ peak of the rubber-like polymer of the present embodiment is 20 °C or higher, it is possible to achieve the effect of simultaneously improving wet skid resistance and abrasion resistance. Therefore, in the rubber-like polymer of the present embodiment, the half-value width (FWHM) value of the tanδ peak is 20 °C or higher, and in order to optimally realize the above-described effect, it is preferably 20 °C or higher and 80 °C or lower.

[0073] The rubber-like polymer of the present embodiment may contain a structural unit derived from an aromatic vinyl compound (hereinafter, also referred to as "aromatic vinyl monomer").

[0074] The aromatic vinyl compound is not particularly limited, and examples thereof include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, α-methylstyrene, vinyl ethylbenzene, vinyl xylene, vinyl naphthalene, and diphenylethylene. Among these, styrene is preferable from the viewpoint of easy industrial availability. These may be used alone or in combination of two or more.

[0075] Further, the rubber-like polymer of the present embodiment is preferably a hydrogenated product of a copolymer of a conjugated diene compound and an aromatic vinyl compound (hereinafter, also referred to as "conjugated diene-aromatic vinyl copolymer").

[0076] In the rubber-like polymer of the present embodiment, from the viewpoints of the breaking strength and tear strength of the vulcanizate, the content of the aromatic vinyl monomer unit is preferably 25% by mass or more, more preferably 28% by mass or more, and even more preferably 31% by mass or more. On the other hand, from the viewpoints of crosslinkability and abrasion resistance when forming a vulcanizate, the content of the aromatic vinyl monomer unit is preferably 45% by mass or less, more preferably 43% by mass or less, and even more preferably 41% by mass or less.

[0077] The content of the aromatic vinyl monomer unit in the rubber-like polymer of the present embodiment can be controlled within the above numerical range, for example, by adjusting the addition amount of the aromatic vinyl monomer in the polymerization step.

[0078] Here, the content of the aromatic vinyl monomer unit can be 1 measured using 1H-NMR. Specifically, it is measured according to the method described in the examples below.

[0079] When the rubber-like polymer of the present embodiment is a hydrogenated product of a conjugated diene-aromatic vinyl copolymer, from the viewpoint of improving abrasion resistance, it is preferable that the proportion of the aromatic vinyl monomer unit existing alone is larger.

[0080] Also, the content of the aromatic vinyl monomer block in the rubber-like polymer of the present embodiment is preferably less than 10.0% by mass, more preferably 9.0% by mass or less, even more preferably 8.0% by mass or less, still more preferably 7.0% by mass or less, and particularly preferably 6.0% by mass or less. The lower limit of the content of the aromatic vinyl monomer block in the rubber-like polymer of the present embodiment is not particularly limited, but is, for example, 0.1% by mass or more. In addition, in this specification, the "aromatic vinyl monomer block" is defined as a structure in which 8 or more aromatic vinyl monomer units are linked in a chain.

[0081] The method for measuring the aromatic vinyl monomer block is not particularly limited. For example, as described in International Publication No. 2014 / 133097, known methods such as measuring the chain of styrene units using NMR can be mentioned. As other methods, a method of decomposing the polymer by Kolthoff's method (the method described in I.M. KOLTHOFF, et al., J. Polym. Sci. 1, 429 (1946)) using the rubber-like polymer before hydrogenation as a sample and analyzing the amount of polystyrene insoluble in methanol can be mentioned.

[0082] In the rubber-like polymer of this embodiment, since a small amount of aromatic vinyl monomer block is present, a portion with a locally high glass transition temperature is generated. Therefore, in the temperature-dependent tanδ graph obtained from dynamic viscoelasticity analysis using a rheometry system (ADVANCED RHEOMETRIC EXPANSION SYSTEM, ARES), the full width at half maximum (FWHM) value of the tanδ peak appearing in the temperature range of -100°C to 100°C tends to broaden. On the other hand, when the content of the aromatic vinyl monomer block is below the above upper limit value, separation between the portion containing the aromatic vinyl monomer block and the portion not containing the aromatic vinyl monomer block can be suppressed, and the rubber-like polymer tends to be suppressed from phase separation. From such a viewpoint, in the rubber-like polymer of this embodiment, the content of the aromatic vinyl monomer block is preferably in the above-described range.

[0083] The content of the aromatic vinyl monomer block in the rubber-like polymer of this embodiment can be controlled within the above numerical range by adjusting the addition method of the aromatic vinyl compound, the addition amount of the polymerization aid, the polymerization temperature, and the like.

[0084] The rubber-like polymer of the present embodiment may have one peak (unimodal) in the molecular weight distribution curve obtained by GPC measurement, or may have two or more peaks. Its molecular weight distribution may be 1.0 to 3.0, preferably 1.0 to 2.5, more preferably 1.0 to 2.0, and even more preferably 1.0 or more and less than 1.7.

[0085] Generally, in continuous polymerization, a unimodal and broad molecular weight distribution appears, so although the processability is excellent, the tensile and viscoelastic properties are poor. In batch polymerization, a bimodal and narrow molecular weight distribution appears, so although the tensile and viscoelastic properties are excellent, there are problems of poor processability and low productivity. However, when the manufacturing method described later according to one embodiment of the present embodiment is applied, it is possible to selectively narrow the molecular weight distribution as much as possible even in continuous production, and thereby it is easy to control the balance of physical properties between processability, tensile properties, and viscoelastic properties.

[0086] When the rubber-like polymer of the present embodiment is a hydrogenated rubber-like polymer obtained by hydrogenating a rubber-like polymer having a broad molecular weight distribution, a distribution occurs in the length of the structural formula (4), and since a rubber-like polymer having a wide full width at half maximum (FWHM) value of the tanδ peak can be obtained by the orientation of the components of the structural formula (4), it is preferable.

[0087] The rubber-like polymer according to this embodiment may have a silicon atom (Si) content and a nitrogen atom (N) content of 30 ppm or more, or 30 ppm to 1000 ppm, respectively, based on the total mass of the rubber-like polymer. Further, in the rubber-like polymer according to this embodiment, the lower limit of the content of the silicon atom (Si) and the nitrogen atom (N) is preferably 50 ppm or more, or 100 ppm or more, respectively, based on the total mass of the rubber-like polymer. On the other hand, the upper limit of the content of the silicon atom (Si) and the nitrogen atom (N) is preferably 700 ppm or less, or more preferably 500 ppm or less, respectively. When the contents of the silicon atom (Si) and the nitrogen atom (N) are within the above ranges, the mechanical properties such as the tensile properties and viscoelastic properties of the rubber composition containing the rubber-like polymer tend to be excellent. On the other hand, the Si and N may be derived from a compound having a modifying functional group such as a modifier, a modification initiator, or a modified monomer described later.

[0088] The Si and N contents can be controlled within the above numerical ranges, for example, by adjusting the addition amount and type of a coupling agent or a modifier having a nitrogen atom-containing group described later.

[0089] The rubber-like polymer of this embodiment is preferably a modified rubber-like polymer modified with a modifier. Specifically, the rubber-like polymer of this embodiment is preferably a modified rubber-like polymer obtained by subjecting the active terminal of a copolymer obtained through, for example, a polymerization step and, if necessary, a branching step using a branching agent, to a modification reaction using a reactive compound (hereinafter also referred to as a "modifier").

[0090] In the modification step of performing a modification reaction using a modifier, a modification reaction is carried out on one end of the active terminal of the rubber-like polymer with a predetermined modifier to obtain a modified rubber-like polymer.

[0091] The rubber-like polymer of the present embodiment preferably contains a nitrogen atom. The rubber-like polymer containing a nitrogen atom can be obtained, for example, by performing a modification reaction using a modifier having a nitrogen atom-containing group described below. Note that the content of the nitrogen atom in the rubber-like polymer of the present embodiment is as described above.

[0092] When the rubber-like polymer coupled using a modifier having a nitrogen atom-containing group is made into a rubber composition containing a filler or the like, the dispersibility of fillers such as silica and carbon black becomes good, the processability of the rubber composition containing a filler or the like is good, and when the rubber composition is made into a vulcanized product, the abrasion resistance and the breaking strength are good.

[0093] As the modifier containing a nitrogen atom, from the viewpoints of polymerization productivity and high modification rate, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, carbonyl compounds containing a nitrogen-containing functional group (hereinafter also referred to as "nitrogen group-containing"), nitrogen group-containing vinyl compounds, nitrogen group-containing epoxy compounds, nitrogen group-containing alkoxysilane compounds, etc. are preferable.

[0094] Further, from the viewpoint of improving the viscosity reduction of the crosslinked product (for example, crosslinked rubber composition) obtained using the rubber-like polymer of the present embodiment and reducing the occurrence of cracks in the compounded sheet, it is preferable to use a modifier (hereinafter, "coupling agent") capable of obtaining a branched structure simultaneously with the modification reaction. The higher the number of branches of the coupling agent, the better. The number of branches of the coupling agent is not particularly limited, but from the viewpoint of improving processability, 3 or more branches are preferable, and 4 or more branches are more preferable. The upper limit of the number of branches is not particularly limited, but from the viewpoint of productivity, 30 or less branches are preferable.

[0095] As these coupling agents containing a nitrogen atom, from the viewpoint of reactivity, nitrogen group-containing alkoxysilane compounds and nitrogen group-containing polyfunctional modifiers can be preferably mentioned.

[0096] Examples of the nitrogen group-containing alkoxysilane compounds include, but are not limited to, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(5-trimethoxysilylpentyl)-1-aza-2-silacycloheptane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy,2-methyl-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy,2-ethyl-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2-methoxy,2-methyl-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2-ethoxy,2-ethyl-1-(3-diethoxyethylsilylpropyl)-1-aza-2-silacyclopentane, tris(3-trimethoxysilylpropyl)amine, tris(3-methyldimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-methyldiethoxysilylpropyl)amine, tris(trimethoxysilylmethyl)amine, tris(2-trimethoxysilylethyl)amine, tris(4-trimethoxysilylbutyl)amine, 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-(3-(bis(3-(trimethoxysilyl)propyl)amino)propyl)-N-methyl-N'-(3-(methyl(3-(trimethoxysilyl)propyl)amino)propyl)-N'-(3-(trimethoxysilyl)propyl)-1,3-propanediamine.

[0097] Examples of the nitrogen group-containing polyfunctional modifier include, but are not limited to, compounds having one or more functional groups selected from an epoxy group, a carbonyl group, a carboxylic acid ester group, a carboxylic acid amide group, an acid anhydride group, a phosphate ester group, a phosphite ester group, an episulfide group, a thiocarbonyl group, a thiocarboxylic acid ester group, a dithiocarboxylic acid ester group, a thiocarboxylic acid amide group, an imino group, an ethyleneimino group, a halogen group, an alkoxysilyl group, an isocyanate group, a thioisocyanate group, a conjugated diene group, and an arylvinyl group, and compounds having at least one nitrogen atom in the compound.

[0098] In the calculation of the number of moles of the functional group, one alkoxy group per one of the epoxy group, carbonyl group, episulfide group, thiocarbonyl group, imino group, ethyleneimino group, halogen group, conjugated diene group, arylvinyl group, and alkoxysilyl group is regarded as monofunctional, and the carboxylic acid ester group, carboxylic acid amide group, acid anhydride group, thiocarboxylic acid ester group, dithiocarboxylic acid ester group, thiocarboxylic acid amide group, isocyanate group, and thioisocyanate group are regarded as difunctional, and the phosphate ester group and phosphite ester group are regarded as trifunctional and should be calculated accordingly.

[0099] The polyfunctional modifier that can be preferably used for modifying the rubber-like polymer of the present embodiment is one in which the sum of the functionality numbers of the above functional groups in one molecule is 2 or more, and more preferably a polyfunctional modifier in which the sum of the functionality numbers is 3 or more.

[0100] When the rubber-like polymer of the present embodiment is a hydrogenated rubber-like polymer, in addition to the coupling agent and modifier described above, a polyfunctional modifier described later and a coupling agent not containing a nitrogen atom can also be used.

[0101] Examples of the polyfunctional modifier include, but are not limited to, polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether and glycerin triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenyl groups such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; glycidylamine compounds such as diglycidylaniline, diglycidyl orthotoluidine, tetraglycidyl metaxylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; compounds having an epoxy group and other functional groups such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltributoxysilane, epoxy-modified silicone, epoxidized soybean oil, and epoxidized linseed oil.

[0102] Examples of the coupling agent not containing a nitrogen atom include, but are not limited to, alkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, and alkyltriphenoxysilane; halogenated silane compounds such as silicon tetrachloride, silicon tetrabromide, silicon tetraiodide, monomethyltrichlorosilane, monoethyltrichlorosilane, monobutyltrichlorosilane, monohexyltrichlorosilane, monomethyltribromosilane, and bistrichlorosilylethane; and alkoxyhalogenated silane compounds such as monochlorotrimethoxysilane, monobromotrimethoxysilane, dichlorodimethoxysilane, dibromodimethoxysilane, trichloromethoxysilane, and tribromomethoxysilane.

[0103] Furthermore, examples of the coupling agent that does not contain a nitrogen atom include tin halide compounds such as tin tetrachloride, tin tetrabromide, monomethyltin trichloride, monoethyltin trichloride, monobutyltin trichloride, monophenyltin trichloride, and bistrichlorostannylethane; polyhalogenated phosphorus compounds such as trichlorophosphine and tribromophosphine; phosphite ester compounds such as trisnonylphenyl phosphite, trimethyl phosphite, and triethyl phosphite; and phosphate ester compounds such as trimethyl phosphate and triethyl phosphate.

[0104] In addition, as the modifier for modifying the rubber-like polymer of the present embodiment, a terminal modifier may be used. Examples of the terminal modifier include, but are not limited to, 1,3-diethyl-2-imidazolinone, 1,3-dimethyl-2-imidazolinone, 1,3-dipropyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 1-methyl-3-propyl-2-imidazolinone, 1-methyl-3-butyl-2-imidazolinone, 1,3-dihydro-1,3-dimethyl-2H-imidazol-2-one, and the like.

[0105] In this specification, unless otherwise specified, the "modification rate" represents the mass ratio of the polymer having a nitrogen atom-containing functional group to the total amount of the rubber-like polymer.

[0106] For example, when a nitrogen atom-containing modifier is reacted with the terminal of the polymer, the mass ratio of the polymer having a nitrogen atom-containing functional group by the nitrogen atom-containing modifier to the total amount of the polymer is represented as the modification rate.

[0107] On the other hand, when the polymer is branched by a branching agent containing a nitrogen atom, the resulting copolymer will have a nitrogen atom-containing functional group. Therefore, this branched polymer will also be counted when calculating the modification rate.

[0108] That is, in this specification, a coupling polymer with a modifier having a nitrogen atom-containing functional group and / or a branched polymer with a branching agent having a nitrogen atom-containing functional group, and the total mass ratio thereof is the "modification rate".

[0109] From the viewpoints of processability, abrasion resistance, fracture strength, and balance with compression set, in the rubber-like polymer of this embodiment, the modification rate measured by the column adsorption GPC method (hereinafter, also simply referred to as "modification rate") is preferably 5% or more and 99% or less with respect to the total amount of the rubber-like polymer.

[0110] The modification rate is more preferably 10% or more, still more preferably 20% or more, particularly preferably 30% or more, and especially preferably 40% or more. The upper limit of the modification rate is not particularly limited, but is, for example, 99% or less.

[0111] The modification rate can be measured, for example, by chromatography that can separate a functional group-containing modified component and an unmodified component.

[0112] As a method using this chromatography, there is a method (column adsorption GPC method) in which a column for gel permeation chromatography filled with a polar substance such as silica that adsorbs a specific functional group is used, and an internal standard of a non-adsorbed component is used for comparison for quantification.

[0113] More specifically, the modification rate can be determined by measuring the adsorption amount to the silica column from the difference between the chromatogram measured with a polystyrene-based gel column and the chromatogram measured with a silica-based column for a sample solution containing a sample and a low-molecular-weight internal standard polystyrene.

[0114] Even more specifically, the modification rate can be measured by the method described in the examples.

[0115] In the rubber-like polymer of this embodiment, the modification rate can be controlled, for example, by adjusting the addition amount of the modifier and the reaction method, and thereby can be controlled to be 5% or more and 99% or less.

[0116] For example, as a polymerization initiator, a method of polymerizing using an organolithium compound having at least one nitrogen atom in the molecule described later, a method of copolymerizing a monomer having at least one nitrogen atom in the molecule, and a method of using a modifier having a structural formula described later are combined, and by controlling the polymerization conditions, the above-mentioned modification rate can be achieved.

[0117] In addition, by modifying the polymerization initiation terminal with an amine, the ratio of the modified polymer in the rubber-like polymer can also be adjusted. The method of modifying the conjugated diene portion of the rubber-like polymer with an amine at the polymerization initiation terminal is not particularly limited, and known methods can be used. For example, as described in JP-A-2018-16678, in the presence of an amine compound having active hydrogen, an organolithium compound is added as a polymerization initiator to obtain a polymer chain having a nitrogen atom at the molecular terminal, which is a preferable method. Examples of the amine compound having active hydrogen include piperidine, hexamethyleneimine, azacyclooctane, 1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, 1,2,3,6-tetrahydropyridine, 3,5-dimethylpiperidine, and the like.

[0118] The Mooney viscosity (ML 1+4 ) of the rubber-like polymer of the present embodiment when using an L-type rotor at 100 °C is preferably 25 or more and 125 or less, more preferably 28 or more and 120 or less, and even more preferably 30 or more and 118 or less from the viewpoints of processability and compression set.

[0119] The Mooney viscosity of the rubber-like polymer of the present embodiment can be measured by the method described in the examples described later.

[0120] The Mooney viscosity (ML 1+4) can be controlled, for example, by the molecular weight, hydrogenation rate, etc. of the rubber-like polymer. Specifically, when the weight average molecular weight Mw of the rubber-like polymer is 200,000 or more and 1,000,000 or less, it can often be controlled within the above range.

[0121] Also, since the Mooney viscosity of the rubber-like polymer tends to increase as the hydrogenation rate increases, when the hydrogenation rate of the rubber-like polymer is 70% or more, it is preferable that the weight average molecular weight Mw of the rubber-like polymer be 100,000 or more and 500,000 or less. When the hydrogenation rate of the rubber-like polymer is 50% or less, it is preferable that the weight average molecular weight Mw of the rubber-like polymer be 200,000 or more and 800,000 or less.

[0122] The rubber-like polymer of this embodiment may be a rubber-like polymer obtained through a hydrogenation step after reacting a modifier or a coupling agent with the active terminal of a polymer obtained through a polymerization step and, if necessary, a branching step.

[0123] When titanium is used as the hydrogenation catalyst component during the production of the rubber-like polymer of this embodiment, the amount of titanium added is preferably 150 ppm or less with respect to the rubber-like polymer before hydrogenation.

[0124] In the rubber-like polymer of this embodiment, the titanium content is preferably 1 ppm or more and 100 ppm or less, more preferably 5 ppm or more and 90 ppm or less, and even more preferably 10 ppm or more and 80 ppm or less. When the titanium content is 100 ppm or less, yellow coloring of the rubber-like polymer can be prevented. On the other hand, when the titanium content is 1 ppm or more, removal equipment is not required, and cost reduction can be achieved.

[0125] When aluminum is used as the hydrogenation catalyst component during the production of the rubber-like polymer of this embodiment, the amount of aluminum added is preferably 6 ppm or less, more preferably 3 ppm or less, and even more preferably not added, with respect to the rubber-like polymer before hydrogenation.

[0126] The aluminum content of the rubber-like polymer of the present embodiment is preferably 2 ppm or less, more preferably 1 ppm or less, and even more preferably not containing aluminum, from the viewpoint of reducing the safety of the catalyst during the hydrogenation reaction. Further, by using lithium or magnesium instead of aluminum, the function as a co-catalyst of aluminum can be complemented.

[0127] Further, from the viewpoints of suppressing the increase in Mooney viscosity (ML viscosity) and the handleability and safety of the hydrogenation catalyst, the hydrogenation catalyst added during the production of the hydrogenated rubber-like polymer preferably has a content of 0.05 mol or less of aluminum per 1 mol of titanium, more preferably a content of 0.04 mol or less of aluminum, even more preferably a content of 0.03 mol or less of aluminum, and particularly preferably not containing aluminum.

[0128] By adjusting the titanium content and aluminum content in the hydrogenation catalyst, the titanium content and aluminum content of the hydrogenated rubber-like polymer can be controlled within the above numerical ranges.

[0129] The rubber-like polymer of the present embodiment is preferably obtained by carrying out a polymerization step using a predetermined polymerization initiator, and preferably carrying out a coupling reaction step using the above-described coupling agent, and then carrying out a hydrogenation step. More preferably, a branching step may be carried out using a branching agent before the coupling reaction step.

[0130] (Polymerization step) As the polymerization initiator used in the polymerization step, at least an organic monolithium compound can be used.

[0131] Examples of the organic monolithium compound include, but are not limited to, low molecular compounds and solubilized oligomeric organic monolithium compounds.

[0132] In addition, examples of the organic monolithium compound include compounds having a carbon-lithium bond, compounds having a nitrogen-lithium bond, and compounds having a tin-lithium bond in terms of the bonding mode between its organic group and lithium.

[0133] The amount of the organic monolithium compound used as the polymerization initiator is preferably determined by the structure of the target copolymer and the molecular weight of the copolymer.

[0134] The amount of the monomer such as the conjugated diene compound used relative to the amount of the polymerization initiator is related to the degree of polymerization. That is, it tends to be related to the number average molecular weight and / or the weight average molecular weight.

[0135] Therefore, in order to increase the molecular weight, it is advisable to adjust in the direction of reducing the amount of the polymerization initiator, and in order to decrease the molecular weight, it is advisable to adjust in the direction of increasing the amount of the polymerization initiator.

[0136] As the organic monolithium compound, from the viewpoint of being used as a method for introducing a nitrogen atom into the rubber-like polymer, an alkyllithium compound having a substituted amino group or a dialkylaminolithium is preferable.

[0137] In this case, a copolymer having a nitrogen atom composed of an amino group at the polymerization initiation end can be obtained.

[0138] The substituted amino group is an amino group having no active hydrogen or having a structure in which the active hydrogen is protected.

[0139] Examples of the alkyllithium compound having an amino group having no active hydrogen include, but are not limited to, 3-dimethylaminopropyl lithium, 3-diethylaminopropyl lithium, 4-(methylpropylamino)butyl lithium, and 4-hexamethyleneiminobutyl lithium.

[0140] Examples of the alkyl lithium compound having an amino group with a structure protecting active hydrogen include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0141] Examples of the dialkylaminolithium 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 hexamethylene imide, lithium pyrrolidide, lithium piperidide, lithium heptamethylene imide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.

[0142] These organic monolithium compounds having a substituted amino group can also be used as solubilized oligomeric organic monolithium compounds by reacting a small amount of polymerizable monomers such as 1,3-butadiene, isoprene, and styrene.

[0143] From the viewpoints of easy industrial availability and easy control of the polymerization reaction, the organic monolithium compound is preferably an alkyl lithium compound. In this case, a copolymer having an alkyl group at the polymerization initiation terminal can be obtained.

[0144] Examples of the alkyl lithium compound include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenyllithium.

[0145] As the alkyl lithium compound, from the viewpoints of easy industrial availability and easy control of the polymerization reaction, n-butyllithium and sec-butyllithium are preferred.

[0146] These organic monolithium compounds may be used alone or in combination of two or more. They may also be used in combination with other organometallic compounds.

[0147] Examples of the other organometallic compounds include alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds.

[0148] Examples of the alkaline earth metal compounds include, but are not limited to, organic magnesium compounds, organic calcium compounds, and organic strontium compounds. Also included are compounds of alkoxides, sulfonates, carbonates, and amides of alkaline earth metals.

[0149] Examples of the organic magnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Examples of the other organometallic compounds include organic aluminum compounds.

[0150] In the polymerization step, the polymerization reaction mode is not limited to the following, and examples include a batch process (also referred to as a "batch process") and a continuous polymerization reaction mode.

[0151] In the continuous process, one or two or more connected reactors can be used. The continuous reactor is not particularly limited, and for example, a tank type with a stirrer or a tubular type is used. In the continuous process, 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.

[0152] When a continuous process is used as the method for producing the rubber-like polymer according to this embodiment, it is not particularly limited. For example, in the presence of a hydrocarbon solvent, a polymerization initiator, and a polar additive, which will be described later, a step (S1) of polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer to produce a living polymer, and a step (S2) of reacting the living polymer produced in the step (S1) with a modifier are included. The step (S1) is continuously carried out in two or more polymerization reactors. When the polymerization conversion rate of the first reactor is 70% to 85%, it is transferred to the second reactor, and a polar additive or a polar additive and a conjugated diene monomer can be additionally added to the second reactor. By such a production method, a rubber-like polymer in which segments having different glass transitions derived from each step are linked can be obtained. As a result, a rubber-like polymer having a wide difference between the glass transition start temperature and the glass transition end temperature can be obtained.

[0153] In the production method, the step (S1) is, as an example, a step in which a polymerization reaction of a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer is carried out by anionic polymerization. As a specific example, it may be living anionic polymerization having an anionic active site at the polymerization terminal by a growth polymerization reaction by an anion. Further, the polymerization in the step (S1) may be temperature-rising polymerization, isothermal polymerization, or isothermal polymerization (adiabatic polymerization). The isothermal polymerization means a polymerization method including a step of polymerizing without arbitrarily adding heat after adding a polymerization initiator and using its own heat of reaction. The temperature-rising polymerization means a polymerization method of arbitrarily adding heat after adding the polymerization initiator to increase the temperature. The isothermal polymerization may mean a polymerization method of maintaining the temperature of the polymer constant by adding heat to increase the heat or taking away the heat after adding the polymerization initiator.

[0154] Also, according to an embodiment of the method for producing a rubber-like polymer according to the present embodiment, the polymerization in the step (S1) may be carried out further containing a diene compound having 1 to 10 carbon atoms in addition to the conjugated diene monomer. In this case, it tends to be possible to prevent the formation of gel on the wall surface of the reactor during long-term operation. The diene compound is not particularly limited, and as an example, it may be 1,2-butadiene.

[0155] Also, according to an embodiment of the method for producing a rubber-like polymer according to the present embodiment, the polymerization in the step (S1) is carried out in two or more polymerization reactors. At this time, the polymerization conversion rate in the first polymerization reactor among the polymerization reactors may be 70% or more and 85% or less, or 70% to 80%. That is, in the step (S1), it is preferable to carry out the polymerization until the polymerization conversion rate in the first polymerization reactor becomes 70% or more, 70% or more and 85% or less, or 70% or more and 80% or less.

[0156] When the polymerization conversion rate in the first polymerization reactor is within the above range, side reactions that occur as the polymer is formed after the start of the polymerization reaction are suppressed, and since it is easy to control the fine structure of the polymer during polymerization, the half-width (FWHM) value of the tanδ peak tends to be widened.

[0157] The polymerization in the first reactor is not particularly limited, and as an example, it may be carried out in a temperature range of 80°C or lower, -20°C to 80°C, 0°C to 80°C, 0°C to 70°C, or 10°C to 70°C. When the polymerization temperature in the first reactor is within the above range, the molecular weight distribution of the polymer tends to be adjusted narrowly and the physical properties are excellent.

[0158] According to an embodiment of the method for producing a rubber-like polymer according to the present embodiment, the step (S1) is carried out in two or more reactors. After the polymerization is carried out to the above-mentioned polymerization conversion rate in the first reactor, it is transferred to the second reactor, and a polar additive or a conjugated diene monomer is additionally charged into the second reactor.

[0159] At this time, the polar additive to be additionally added, or the polar additive and the conjugated diene monomer may be added simultaneously or sequentially. They may be added at one point among the points within the above-described polymerization conversion rate range, divided and added at a plurality of points within the points of the above range, or continuously added within the points of the above range.

[0160] The additional addition of the polar additive, or the polar additive and the conjugated diene monomer, can be a means to realize the glass transition temperature characteristics of the produced rubber-like polymer together with the control of the polymerization conversion rate in the first reactor. This is because, by additionally adding the polar additive, it is possible to further apply power to the polymerization reaction after a specific polymerization conversion rate to cause deformation of the fine structure.

[0161] In particular, when the polar additive homopolymerizes the conjugated diene monomer, the ratio of the 1,2-bond to the 1,4-bond can be controlled by controlling the reaction rate. When copolymerizing the conjugated diene monomer and the aromatic vinyl monomer, it tends to induce the easy formation of a random copolymer by correcting the difference in the reaction rates between these monomers.

[0162] At this time, the polar additive to be additionally added may be used in an appropriate amount so that the full width at half maximum (FWHM) value of the tanδ peak becomes wider. For example, the polar additive to be additionally added may be used at a ratio of preferably 0.001 g to 10 g, or 0.01 g to 1.0 g, more preferably 0.02 g to 0.5 g, based on 100 g in total of the monomers used at the start of polymerization.

[0163] Also, the conjugated diene monomer selectively added additionally may be used in an amount of preferably 5 g to 25 g, or 5 g to 20 g, based on 100 g of the monomer used at the start of polymerization. When the polar additive and the conjugated diene monomer added additionally are controlled to amounts as described above, it is easy to control the glass transition temperature of the polymer, and further fine adjustment is possible, and the full width at half maximum (FWHM) value of the tanδ peak tends to be widened.

[0164] The total amount of the polar additive used in the polymerization in the step (S1) is preferably 0.001 g to 50 g, or may be used at a ratio of 0.002 g to 1.0 g, based on 100 g of the total monomers. As another example, the total amount of the polar additive may be preferably more than 0 g to 1 g, 0.01 g to 1 g, or 0.1 g to 0.9 g, based on 100 g of the total polymerization initiators. Here, the total amount of the polar additive means the content including the additionally added polar additive.

[0165] The polymerization in the second reactor is not particularly limited. As an example, it may be carried out in a temperature range of 80°C or lower, -20°C to 80°C, 0°C to 80°C, 0°C to 70°C, or 10°C to 70°C. When the polymerization temperature in the second reactor is within the above range, the molecular weight distribution of the polymer can be adjusted to be narrow, and there is a tendency to be excellent in improving physical properties.

[0166] On the other hand, in controlling the full width at half maximum (FWHM) value of the tanδ peak obtained additionally from the dynamic viscoelasticity analysis, the polymerization temperatures in the first reactor and the second reactor can also have an influence. In this case, it is more preferable to control the polymerization temperature of the second reactor to be equal to or lower than the polymerization temperature of the first reactor, and the polymerization temperature of the second reactor is preferably 60°C or higher.

[0167] On the other hand, the polymerization conversion rate is not particularly limited. As an example, it may be determined by measuring the solid concentration in the polymer solution containing the polymer during polymerization. As a specific example, although not particularly limited, for example, in order to secure the polymer solution, a cylinder-shaped container is attached to the outlet of each polymerization reactor to fill a certain amount of the polymer solution into the cylinder-shaped container, the cylinder-shaped container is separated from the reactor, after measuring the weight (A) of the cylinder filled with the polymer solution, the polymer solution filled in the cylinder-shaped container is transferred to an aluminum container, for example, an aluminum dish, and the weight (B) of the cylinder-shaped container from which the polymer solution has been removed is measured. The aluminum container containing the polymer solution is dried in an oven at 140°C for 30 minutes, and after measuring the weight (C) of the dried polymer, it may be calculated by the following formula 1.

[0168] [Number]

[0169] In the above formula (1), the total solid content is the total solid content (monomer content) in the polymer solution separated from each reactor, which is the mass percentage of the solid content with respect to 100% of the polymer solution. Exemplarily, when the total solid content is 20% by mass, when applying it to the above formula (1), it may be substituted as 20 / 100, that is, 0.2, and then calculated.

[0170] On the other hand, the polymer polymerized in the second reactor may be sequentially transferred to the final polymerization reactor, and polymerization may be finally carried out until the polymerization conversion rate reaches 95% or more. After polymerization in the second reactor, the polymerization conversion rate for each reactor from the third reactor or from the third reactor to the last polymerization reactor may be appropriately adjusted for each reactor to adjust the molecular weight distribution. Then, a reaction terminator for deactivating the active site may be added. When attempting to produce a modified rubber-like polymer, the living polymer may be transferred to the modification reaction step. The reaction terminator may be applied without limitation as long as it is a substance generally used in the technical field. Further, the living polymer produced by the step (S1) may mean a polymer in which a polymer anion and an organometallic cation of a polymerization initiator are bonded.

[0171] The step (S2) is a modification step of reacting the living polymer produced in the step (S1) with a modifier, and the anionic active site of the living polymer can react with the alkoxy group bonded to the silane of the modifier. The modifier may be used in an amount of 0.01 mmol to 10 mmol based on 100 g of the total monomers. As another example, the modifier may be used in a molar ratio of 1:0.1 to 10, 1:0.1 to 5, or 1:0.1 to 1:3 based on 1 mol of the polymerization initiator in the step (S1).

[0172] According to one embodiment of the method for producing a rubber-like polymer according to this embodiment, the modifier may be charged into a modification reactor, and the step (S2) may be carried out in the modification reactor. As another example, the modifier may be charged into a transfer section for transferring the living polymer produced in the step (S1) to a modification reactor for carrying out the step (S2), and the reaction may be carried out by mixing the living polymer and the modifier in the transfer section. At this time, the reaction may be a modification reaction in which the modifier is simply bonded to the living polymer, or a coupling reaction in which the living polymer is linked with reference to the modifier.

[0173] On the other hand, the method for producing the modified rubber-like polymer may further include a step of additionally charging a conjugated diene monomer into the living polymer produced in the step (S1) and reacting it before the modification reaction in the step (S2). In this case, it is more advantageous for the subsequent modification reaction. At this time, the conjugated diene monomer may be charged in an amount of 1 mol to 100 mol per 1 mol of the living polymer.

[0174] The method for producing the modified rubber-like polymer according to one embodiment of the method for producing a rubber-like polymer according to this embodiment is a method capable of satisfying the characteristics of the modified rubber-like polymer described above. As described above, the effects to be achieved by the present invention can be achieved when the above characteristics are satisfied. However, in the case of other polymerization conditions, by variously controlling them, the physical properties of the modified rubber-like polymer according to this embodiment can be realized.

[0175] For a batch reactor, for example, a tank-type reactor equipped with a stirrer is used. In a batch process, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, the monomer is continuously or intermittently added during polymerization, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is discharged after the polymerization is completed.

[0176] In the method for producing a rubber-like polymer of this embodiment, in order to obtain a copolymer having a high proportion of active ends, a continuous process is preferable in which the polymer can be continuously discharged and subjected to the next reaction in a short time.

[0177] The polymerization step of the rubber-like polymer of this embodiment is preferably carried out in an inert solvent. The solvent is not particularly limited, and examples thereof include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents include, but are not limited to, the following: 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 composed of mixtures thereof.

[0178] Before subjecting to the polymerization reaction, treating allenes and acetylenes, which are impurities, with an organometallic compound is preferable because a polymer having a high concentration of active terminals tends to be obtained, and a modified rubber-like polymer having a high modification rate tends to be obtained.

[0179] In the polymerization step, a polar compound (polar substance) may be added. An aromatic vinyl compound can be copolymerized randomly with a conjugated diene compound, and it also tends to be used as a vinylating agent for controlling the microstructure of the conjugated diene part. Also, it tends to be effective in promoting the polymerization reaction and the like.

[0180] Examples of the polar compound include, but are not limited to, the following: 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-butyrate, sodium tert-butyrate, and sodium amylate; phosphine compounds such as triphenylphosphine, etc. can be used.

[0181] These polar compounds may be used alone or in combination of two or more thereof.

[0182] The amount of the polar compound used is not particularly limited and can be selected according to the purpose and the like, but it is preferably 0.01 mol or more and 10 mol or less with respect to 1 mol of the polymerization initiator.

[0183] Such a polar compound (vinylating agent) can be used in an appropriate amount according to the desired amount of 1,2-vinyl bonds as a regulator for the microstructure of the conjugated diene moiety in the polymer. Many polar compounds tend to have an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and can be used as an agent for adjusting the distribution of the aromatic vinyl compound and the amount of styrene blocks.

[0184] The method for randomizing the conjugated diene compound and the aromatic vinyl compound is not particularly limited. For example, as described in JP-A-59-140211, a copolymerization reaction may be initiated with the total amount of styrene and a part of 1,3-butadiene, and the remaining 1,3-butadiene may be intermittently added during the copolymerization reaction.

[0185] The polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds. From the viewpoint of productivity, it is more preferably 0°C or higher, and even more preferably 120°C or lower. Being within such a range tends to ensure a sufficient reaction amount of the modifier with respect to the active terminal after the polymerization is completed. Even more preferably, it is 50°C or higher and 100°C or lower.

[0186] (Coupling step) A coupling reaction is carried out on the active terminal of the copolymer obtained through the above-described polymerization step and, if necessary, a branching step using a predetermined branching agent, with the above-described coupling agent or a modifier having a nitrogen atom-containing group.

[0187] (Deactivator addition step, neutralizer addition step) In the method for producing a rubbery polymer according to this embodiment, after the coupling step, a deactivator, a neutralizing agent, etc. may be added to the polymer solution as necessary.

[0188] The deactivator is not limited to the following, and examples thereof include water; alcohols such as methanol, ethanol, and isopropanol.

[0189] The neutralizing agent is not limited to the following, and examples thereof include carboxylic acids such as stearic acid, oleic acid, and versatic acid (a mixture of carboxylic acids having 9 to 11 carbon atoms, centered around 10 carbon atoms, and having many branches); aqueous solutions of inorganic acids, and carbon dioxide gas.

[0190] (Hydrogenation step) In the method for producing a rubbery polymer according to this embodiment, the above-described polymerization step, and optionally, the branching step, the coupling step, and further, optionally, the deactivator addition step may be performed, and the above-described hydrogenation reaction may be carried out.

[0191] (Stabilizer for rubber) In the method for producing a rubbery polymer according to this embodiment, from the viewpoints of preventing gel formation after polymerization and improving stability during processing, it is preferable to add a stabilizer for rubber.

[0192] The stabilizer for rubber is not limited to the following, and known ones can be used. For example, antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenyl) propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol are preferable.

[0193] (Desolventization step) In the method for producing the rubber-like polymer of the present embodiment, as a method for obtaining the obtained rubber-like polymer from the polymer solution, a known method can be used. As the method, although not particularly limited, for example, a method in which after separating the solvent by steam stripping or the like, the polymer is filtered off, and then it is dehydrated and dried to obtain the polymer; a method in which it is concentrated in a flashing tank and then devolatilized by a vent extruder or the like; a method in which it is directly devolatilized by a drum dryer or the like can be mentioned.

[0194] The rubber composition of the present embodiment may contain 100 parts by mass of the above-described rubber-like polymer and 0.1 part by mass or more and 200 parts by mass or less of a filler.

[0195] From the viewpoint of exhibiting a reinforcing effect, the content of the filler in the rubber composition of the present embodiment is more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, based on 100 parts by mass of the above-described rubber-like polymer. On the other hand, from the viewpoint of sufficiently dispersing the filler and making the processability and mechanical strength of the rubber composition practically sufficient, the content of the filler in the rubber composition of the present embodiment is preferably 150 parts by mass or less based on 100 parts by mass of the above-described rubber-like polymer.

[0196] The filler is not particularly limited, and for example, silica-based fillers, carbon black-based fillers, calcium carbonate, metal oxides, and metal hydrides can be used. These may be used alone or in combination of two or more. Also, fillers other than the above may be contained.

[0197] As the filler, from the viewpoint of improving the fracture characteristics and wet grip properties of the rubber composition of the present embodiment, a silica-based filler or a carbon black-based filler, or a combination thereof is preferable.

[0198] The silica-based filler is not particularly limited, and known ones can be used. However, solid particles containing SiO 2 or Si 3 Al as a structural unit are preferable, SiO 2 or Si3 Solid particles containing Al as the main component of the structural unit are more preferred. Here, the main component refers to a component contained in the silica-based filler in an amount of 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0199] Specific silica-based fillers include, but are not limited to, for example, inorganic fibrous substances such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. Also included are silica-based fillers with a hydrophobized surface and mixtures of silica-based fillers and fillers other than silica-based. Among these, from the viewpoints of strength and abrasion resistance, etc., silica and glass fiber are preferred, and silica is more preferred. Silica is not particularly limited, and examples include dry silica, wet silica, and synthetic silicate silica.

[0200] Examples of carbon black-based fillers include, but are not limited to, carbon blacks of each class such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon black with a nitrogen adsorption specific surface area of 50 m 2 / g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or less is preferred.

[0201] Calcium carbonate is not particularly limited, and examples include calcium carbonate with an average particle diameter of 0.04 μm to 8.0 μm and an oil absorption of 10 to 35 g per 100 g of calcium carbonate.

[0202] Metal oxide refers to solid particles having the chemical formula M x O y (where M represents a metal atom, and x and y each independently represent an integer from 1 to 6) as the main component of the structural unit.

[0203] Examples of metal oxides include, but are not limited to, alumina, titanium oxide, magnesium oxide, and zinc oxide.

[0204] Examples of the metal hydroxide include, but are not limited to, aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0205] The rubber composition of this embodiment may contain a silane coupling agent. The silane coupling agent has a function of strengthening the interaction between the rubber component (rubbery polymer) and the filler (especially inorganic filler), and has an affinity or bonding group for each of the rubber component and the silica-based filler (especially inorganic filler). A compound having a sulfur-bonded portion and an alkoxysilyl group or a silanol group portion in one molecule is preferred. Such compounds are not particularly limited, and examples thereof include bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0206] In the rubber composition of this embodiment, the content of the silane coupling agent is preferably 0.1 part by mass or more and 30 parts by mass or less, more preferably 0.5 part by mass or more and 20 parts by mass or less, and even more preferably 1.0 part by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the above-described filler (especially inorganic filler). When the content of the silane coupling agent is within the above range, the above-described addition effect by the silane coupling agent tends to be more remarkable. (Softening agent for rubber)

[0207] The rubber composition of this embodiment may contain a softening agent for rubber as needed. The softening agent for rubber can be added as needed to further improve the productivity of the rubbery polymer and the processability when the composition contains a filler or the like.

[0208] Examples of the softening agent for rubber include, but are not limited to, extender oil, liquid rubber, resin, and the like.

[0209] The method of adding a softening agent for rubber to a rubber-like polymer or a rubber composition is not limited to the following, but a method of adding the softening agent for rubber to a copolymer solution, mixing it to obtain a polymer solution containing the softening agent for rubber, and then removing the solvent is preferred.

[0210] Preferred extender oils include, for example, aroma oil, naphthenic oil, paraffin oil and the like. Among these, from the viewpoints of environmental safety, oil bleed prevention and wet grip properties, an aroma alternative oil with a polycyclic aromatic (PCA) component of 3% by mass or less according to the IP346 method is preferred. Examples of aroma alternative oils include TDAE (Treated Distillate Aromatic Extracts), MES (Mild Extraction Solvate), etc. shown in Kautschuk Gummi Kunststoffe 52(12)799(1999), and RAE (Residual Aromatic Extracts).

[0211] Preferred liquid rubbers include, but are not limited to, for example, liquid polybutadiene, liquid styrene-butadiene rubber and the like.

[0212] When adding a liquid rubber, in addition to improving the processability when making a rubber composition by blending a rubber-like polymer and a filler, etc., the glass transition temperature of the rubber composition can be shifted to the low temperature side, so that the abrasion resistance, low hysteresis loss property, and low temperature property of the vulcanizate tend to be improved.

[0213] Preferred resins include, but are not limited to, for example, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including tung oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, oligomers of monoolefins, oligomers of diolefins, aromatic hydrocarbon resins, aromatic petroleum resins, hydrogenated aromatic hydrocarbon resins, cycloaliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated tung oil resins, hydrogenated oil resins, esters of hydrogenated oil resins and monofunctional or polyfunctional alcohols, and the like. These resins may be used alone or in combination of two or more. When hydrogenating, all unsaturated groups may be hydrogenated or some may be left.

[0214] As the effects when adding the resin, in addition to improving the processability when making a rubber composition by blending a polymer and a filler, etc., there is a tendency to improve the breaking strength when making a vulcanizate, and also by shifting the glass transition temperature of the rubber composition to the high temperature side, there is a tendency to improve the wet skid resistance.

[0215] The addition amount of an extender oil, liquid rubber or resin, etc. as a softening agent for rubber is preferably 1 part by mass or more and 60 parts by mass or less, more preferably 5 parts by mass or more and 50 parts by mass or less, still more preferably 10 parts by mass or more and 37.5 parts by mass or less with respect to 100 parts by mass of the above rubber-like polymer.

[0216] When adding the softening agent for rubber within the above range, the processability when making a rubber composition by blending a rubber-like polymer and a filler, etc. becomes good, and there is a tendency for the breaking strength and abrasion resistance when making a vulcanizate to be good.

[0217] Specific mixing methods for obtaining the rubber composition of this embodiment are not limited to the following, but for example, melting and kneading methods using general mixers such as open rolls, Banbury mixers, kneaders, single-screw extruders, twin-screw extruders, multi-screw extruders, etc., and methods of dissolving and mixing each component and then heating and removing the solvent can be mentioned.

[0218] Among these, the melting and kneading methods using rolls, Banbury mixers, kneaders, and extruders are preferable from the viewpoints of productivity and good kneading property. Also, either a method of kneading the rubber component and other fillers, silane coupling agents, and additives all at once or a method of mixing them in multiple times is applicable.

[0219] (Vulcanized composition) The rubber composition of this embodiment may be a vulcanized composition obtained by subjecting it to a vulcanization treatment with a vulcanizing agent.

[0220] Vulcanizing agents are not limited to the following, but for example, radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds can be mentioned.

[0221] Sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, high molecular polysulfur compounds, etc. In the rubber composition of this embodiment, the content of the vulcanizing agent is preferably 0.01 part by mass or more and 20 parts by mass or less, more preferably 0.1 part by mass or more and 15 parts by mass or less, based on 100 parts by mass of the rubber-like polymer described above. As the vulcanization method, a conventionally known method can be applied, and the vulcanization temperature is preferably 120°C or more and 200°C or less, more preferably 140°C or more and 180°C or less.

[0222] When vulcanizing, a vulcanization accelerator may be used as necessary.

[0223] As the vulcanization accelerator, conventionally known materials can be used, and examples include, but are not limited to, the following: for example, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, dithiocarbamate-based vulcanization accelerators. Further, as the vulcanization aid, examples include, but are not limited to, zinc white, stearic acid, and triallyl isocyanurate. The content of the vulcanization accelerator is preferably 0.01 part by mass or more and 20 parts by mass or less, more preferably 0.1 part by mass or more and 15 parts by mass or less, based on 100 parts by mass of the rubber-like polymer described above.

[0224] Examples of the organic peroxide include 1,3-bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexene-3, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,2'-bis(tert-butylperoxy)-p-isopropylbenzene, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl peroxide, p-menthane peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, dilauroyl peroxide, diacetyl peroxide, tert-butyl peroxybenzoate, 2,4-dichlorobenzoyl peroxide, p-chlorobenzoyl peroxide, benzoyl peroxide, di(tert-butylperoxy)perbenzoate, n-butyl-4,4-bis(tert-butylperoxy)valerate, tert-butylperoxyisopropyl carbonate, and the like.

[0225] (Other additives) The rubber composition of the present embodiment may contain various additives such as softeners, fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, lubricants, etc., other than those described above, within a range that does not impair the object of the present embodiment.

[0226] As other softeners, known softeners can be used.

[0227] As other fillers, specifically, although not particularly limited, for example, magnesium carbonate, aluminum sulfate, and barium sulfate can be mentioned. As the above heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants, known materials can be used respectively.

[0228] (Use of rubber-like polymer crosslinked product (crosslinked rubber composition)) The crosslinked product (for example, crosslinked rubber composition) obtained using the rubber-like polymer of the present embodiment can be used as packing, gasket, sealing material, vibration-proof rubber, vibration-isolation rubber, conveyor belt, shoe outsole and shoe midsole, automotive weatherstrip, glass run, trunk lid, railway vehicle member, aircraft member, waterproof sheet, engine mount, air spring, rubber glove, medical and hygienic supplies, industrial and various-purpose hoses, battery case, adhesive, wire coating, window frame rubber, rubber roll, rubber rollers for OA equipment and spinning, etc., keypad, keyboard cover, underwater glasses, swimming cap, container bag, marine-related parts, indoor floor material, artificial muscle material, materials for various industrial supplies, etc. In these applications, various molded products can be obtained by molding the crosslinked product (for example, crosslinked rubber composition) obtained using the rubber-like polymer of the present embodiment.

Examples

[0229] Hereinafter, the present invention will be specifically described with reference to examples in detail. However, the examples according to the present invention can be deformed into various forms, and the scope of the present invention should not be construed as being limited to the examples detailed below. The examples of the present invention are provided to more fully explain the present invention to those with average knowledge in the industry.

[0230] [Physical property measurement method] [Styrene content of the rubber-like polymer before hydrogenation, and constituent molar ratios of each structural unit represented by the structural formulas (1) to (4) of the rubber-like polymer, hydrogenation rate, styrene block amount] 1 The content of the aromatic vinyl monomer unit (styrene content) was calculated from the integrated value of the unsaturated bond portion of the rubber-like polymer before hydrogenation by 1H-NMR measurement. Subsequently, a large amount of methanol was added to the reaction solution after the hydrogenation reaction to precipitate and recover the rubber-like polymer. Then, the rubber-like polymer was extracted with acetone and dried under vacuum. This was 1 used as a sample for 1H-NMR measurement to measure the hydrogenation rate of the rubber-like polymer. 1 The conditions for 1H-NMR measurement are described below.

[0231] (Measurement conditions) Measuring instrument: JNM-LA400 (manufactured by JEOL) Solvent: deuterated chloroform Measurement sample: extracted samples before and after hydrogenation of the rubber-like polymer Sample concentration: 50 mg / mL Observation frequency: 400 MHz Chemical shift standard: TMS (tetramethylsilane) Pulse delay: 2.904 seconds Number of scans: 64 times Pulse width: 45° Measurement temperature: 26 °C

[0232] [Styrene block amount] A chain in which 8 or more styrene structural units are consecutive was defined as a styrene block, and the styrene block amount was determined as follows. Using deuterated chloroform as a solvent, the 400 MHz 1 1H-NMR spectrum of the rubber-like polymer was measured. From the spectrum, the ratio of the integrated value in each of the following chemical shift ranges of (X) was determined, and the styrene block amount contained in the rubber-like polymer was determined. Aromatic vinyl compound chain of 8 or more: 6.00 ≦ X < 6.68

[0233] [tanδ peak temperature] Using a rubber-like polymer as a sample, a dynamic mechanical analyzer (TA Instruments, ARES-G2) was used to measure tanδ according to temperature in the temperature range of -100°C to 100°C in torsional mode at a frequency of 10 Hz, a strain of 0.5%, and a heating rate of 5°C / min. The temperature showing the maximum tanδ value in this measurement was defined as the tanδ peak temperature.

[0234] [Half-width at half-maximum (FWHM) value of the tanδ peak] Based on the measurement of the tanδ peak temperature, the full width at half-maximum of the peak was determined from the tanδ graph by temperature obtained from dynamic viscoelasticity analysis using a rheometry system (ADVANCED RHEOMETRIC EXPANSION SYSTEM, ARES), and this value was defined as the half-width at half-maximum (FWHM) value of the tanδ peak.

[0235] [Nitrogen atom content of the rubber-like polymer] Using a rubber-like polymer as a sample, the nitrogen atom content in the rubber-like polymer was measured using a trace nitrogen analyzer (Nitto Seiko Analytic TN-2100H).

[0236] [Weight-average molecular weight of the rubber-like polymer] The weight-average molecular weight of the rubber-like polymer was measured by gel permeation chromatography (GPC). Specifically, the measurement was performed as follows.

[0237] Using a GPC measuring device (trade name "HLC-8320GPC" manufactured by Tosoh Corporation) with three columns filled with a polystyrene-based gel as a filler, a chromatogram was measured using an RI detector (trade name "HLC8020" manufactured by Tosoh Corporation). Based on the calibration curve obtained using standard polystyrene, the weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the rubber-like polymer were determined. The detailed measurement conditions were as follows. The eluent used was THF (tetrahydrofuran) containing 5 mmol / L of triethylamine. For the column, three columns with the trade name "TSKgel SuperMultipore HZ-H" manufactured by Tosoh Corporation were connected in series, and a guard column with the trade name "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation was connected in front of them for use. 10 mg of the sample for measurement was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measuring device and measured under the conditions of an oven temperature of 40 °C and a THF flow rate of 0.35 mL / min.

[0238] (Preparation of Hydrogenation Catalyst) A nitrogen-substituted reaction vessel was charged with 1 liter of dried and purified cyclohexane, 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added, and an n-hexane solution containing 200 mmol of trimethylaluminum was added while stirring thoroughly, and the mixture was reacted at room temperature for about 3 days to obtain a hydrogenation catalyst (TC).

[0239] [Example 1] Into the first of three continuously stirred tank reactors (CSTRs), n-hexane was continuously fed at a flow rate of 5.59 kg / hr, 1,3-butadiene at 0.56 kg / hr, styrene at 0.34 kg / hr, n-butyllithium at 0.55 g / hr, and ditetrahydrofurylpropane as a polar additive at 0.079 g / hr. At this time, the internal temperature of the reactor was maintained at 60 °C, and when the polymerization conversion rate reached 70%, the polymer was transferred from the first reactor to the second reactor through a transfer pipe. Next, the temperature of the second reactor was maintained at 60°C, and n-hexane was continuously fed into the second reactor at a flow rate of 0.065 kg / hr, 1,3-butadiene at a flow rate of 0.097 kg / hr, and ditetrahydrofurylpropane as a polar additive at a flow rate of 1.06 g / hr to participate in the reaction. When the polymerization conversion rate reached 95% or more, the polymer was transferred from the second reactor to the third reactor through a transfer pipe, and N,N-dimethyl-3-(trimethoxysilyl)propane-1-amine (hereinafter also referred to as "N1") was added as a modifier at a flow rate of 0.58 g / hr, and the reaction was carried out for 30 minutes. A part of the obtained modified rubber-like polymer solution was withdrawn and desolventized with a dryer. Furthermore, the hydrogenation catalyst (TC) was added to the rubber-like polymer solution at 50 ppm based on Ti per 100 parts by mass of the rubber-like polymer before hydrogenation, and the reaction was carried out at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C until the hydrogenation rate of the butadiene part reached 76 mol%. To the obtained solution of the rubber-like polymer, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate as an antioxidant was added at 0.3 g per 100 g of the polymer weight, and 0.1 g of 4,6-bis(octylthiomethyl)-o-cresol was added. Then, the rubber-like polymer solution was dropped into warm water to remove the solvent, and a drying treatment was performed with a dryer to obtain a rubber-like polymer A1. Table 1 shows the analysis results of the obtained rubber-like polymer A1 analyzed by the above method.

[0240] [Example 2] A rubber-like polymer A2 was obtained in the same manner as in Example 1, except that the reaction was carried out until the hydrogenation rate of the butadiene part reached 85 mol%. Table 1 shows the analysis results of the obtained rubber-like polymer A2 analyzed by the above method.

[0241] [Example 3] A rubber-like polymer A3 was obtained in the same manner as in Example 1, except that the reaction was carried out until the hydrogenation rate of the butadiene part reached 95 mol%. Table 1 shows the analysis results of the obtained rubber-like polymer A3 analyzed by the above method.

[0242] [Example 4] (A rubbery polymer A4 was obtained in the same manner as in Example 1, except that the reaction was carried out until the hydrogenation rate of the butadiene portion reached 55 mol%. Table 1 shows the analysis results of the obtained rubbery polymer A4 analyzed by the above method.

[0243] [Example 5] (A rubbery polymer A5 was obtained in the same manner as in Example 1, except that the reaction was carried out until the hydrogenation rate of the butadiene portion reached 36 mol%. Table 1 shows the analysis results of the obtained rubbery polymer A5 analyzed by the above method.

[0244] [Example 6] (A rubbery polymer A6 was obtained in the same manner as in Example 1, except that the reaction was carried out until the hydrogenation rate of the butadiene portion reached 21 mol%. Table 1 shows the analysis results of the obtained rubbery polymer A6 analyzed by the above method.

[0245] [Example 7] (A rubbery polymer A7 was obtained in the same manner as in Example 1, except that the modifier was 1,3-dimethyl-2-imidazolidinone (hereinafter also referred to as "N2") and the flow rate thereof was changed to 0.32 g / hr. Table 1 shows the analysis results of the obtained rubbery polymer A7 analyzed by the above method.

[0246] [Example 8] (A rubbery polymer A8 was obtained in the same manner as in Example 1, except that no modifier was added. Table 1 shows the analysis results of the obtained rubbery polymer A8 analyzed by the above method.

[0247] [Comparative Example 1] (A rubbery polymer A9 was obtained in the same manner as in Example 1, except that hydrogenation was not carried out. Table 1 shows the analysis results of the obtained rubbery polymer A9 analyzed by the above method.

[0248] [Example 9] The flow rate of 1,3-butadiene was changed to 0.56 kg / hr in the first reactor and 0.097 kg / hr in the second reactor, the flow rate of styrene was 0.26 kg / hr, and the flow rate of ditetrahydrofurylpropane was 0.10 g / hr in the first reactor and 1.32 g / hr in the second reactor. A rubbery polymer A10 was obtained in the same manner as in Example 1, except that the reaction was carried out until the hydrogenation rate of the butadiene portion reached 82 mol%. Table 2 shows the analysis results of the obtained rubbery polymer A10 analyzed by the above method.

[0249] [Comparative Example 2] A rubbery polymer A11 was obtained in the same manner as in Example 9, except that hydrogenation was not carried out. Table 2 shows the analysis results of the obtained rubbery polymer A11 analyzed by the above method.

[0250] [Example 10] The flow rate of 1,3-butadiene was changed to 0.79 kg / hr in the first reactor and 0.14 kg / hr in the second reactor, the flow rate of styrene was 0.080 kg / hr, and the flow rate of ditetrahydrofurylpropane was 0.088 g / hr in the first reactor and 1.2 g / hr in the second reactor. A rubbery polymer A12 was obtained in the same manner as in Example 1, except that the reaction was carried out until the hydrogenation rate of the butadiene portion reached 73 mol%. Table 3 shows the analysis results of the obtained rubbery polymer A12 analyzed by the above method.

[0251] [Comparative Example 3] A rubbery polymer A13 was obtained in the same manner as in Example 10, except that hydrogenation was not carried out. Table 3 shows the analysis results of the obtained rubbery polymer A13 analyzed by the above method.

[0252] [Example 11] The flow rate of 1,3-butadiene was changed such that it was 0.70 kg / hr in the first reactor and 0.12 kg / hr in the second reactor, the flow rate of styrene was 0.19 kg / hr, and the flow rate of ditetrahydrofurylpropane was 0.045 g / hr in the first reactor and 0.6 g / hr in the second reactor. A rubbery polymer A14 was obtained in the same manner as in Example 1, except that the reaction was carried out until the hydrogenation rate of the butadiene portion reached 56 mol%. Table 4 shows the analysis results of the obtained rubbery polymer A14 analyzed by the above method.

[0253] [Example 12] A rubbery polymer A15 was obtained in the same manner as in Example 11, except that the reaction was carried out until the hydrogenation rate of the butadiene portion reached 78 mol%. Table 4 shows the analysis results of the obtained rubbery polymer A15 analyzed by the above method.

[0254] [Example 13] A rubbery polymer A16 was obtained in the same manner as in Example 11, except that the reaction was carried out until the hydrogenation rate of the butadiene portion reached 95 mol%. Table 4 shows the analysis results of the obtained rubbery polymer A16 analyzed by the above method.

[0255] [Example 14] A rubbery polymer A17 was obtained in the same manner as in Example 12, except that the feeding point of styrene was changed to the second reactor instead of the first reactor. Table 4 shows the analysis results of the obtained rubbery polymer A17 analyzed by the above method.

[0256] [Comparative Example 4] A rubbery polymer A18 was obtained in the same manner as in Example 11, except that hydrogenation was not carried out. Table 4 shows the analysis results of the obtained rubbery polymer A18 analyzed by the above method.

[0257] [Table 1]

[0258]

Table 2

[0259]

Table 3

[0260]

Table 4

[0261] [Comparative Example 5] (Co-polymerization and Modification Step) An autoclave with a capacity of 40 L, equipped with a stirrer and a jacket and capable of temperature control, was used as a reactor. 1,980 g of 1,3-butadiene, 1,020 g of styrene, 21,000 g of cyclohexane, 29.1 mmol of tetrahydrofuran (THF) and 2.2 mmol of 2,2-bis(2-oxolanyl)propane (BOP) as polar substances, which had been purified in advance, were put into the reactor, and the internal temperature of the reactor was maintained at 43°C. 25.7 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the start of the polymerization reaction, the temperature in the reactor increased due to the heat generated by the polymerization, and the final temperature in the reactor was 78°C. 15.2 mmol of tetraglycidyl-1,3-bis(aminomethyl)cyclohexane (hereinafter also referred to as "N3") was added to this polymer solution as a modifier and reacted for 15 minutes. Then, 15.2 mmol of methanol was added as a reaction terminator. (Hydrogenation Step) Furthermore, the hydrogenation catalyst (TC) was added to the polymer solution at 50 ppm based on Ti per 100 parts by mass of the polymer before hydrogenation, and the reaction was carried out at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C until the hydrogenation rate of the butadiene part reached 82%. To the solution of the obtained polymer, 12.6 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 3.0 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants. Then, the conjugated diene polymer solution was dropped into warm water to remove the solvent, and the resulting product was dried using a dryer to obtain a rubbery polymer B1. Table 5 shows the analysis results of the obtained rubbery polymer B1 analyzed by the above method.

[0262] [Example 15] A rubbery polymer B2 was obtained in the same manner as in Comparative Example 5, except that the hydrogenation step was changed as follows. (Hydrogenation step) A reactor with an internal volume of 40 L, equipped with a rotary stirrer with a rotation speed of 114 rpm, an L / D (L: height of the reactor, D: diameter of the reactor) of 2.2, three nozzles each at the top and bottom (at the top: nozzle A, nozzle B, and nozzle C; at the bottom: nozzle D, nozzle E, and nozzle F), and one nozzle (nozzle G) on the central side of the reactor was used. The temperature of the reactor was adjusted to 90°C. Then, the conjugated diene polymer solution obtained above was supplied from nozzle A at the top of the reactor at a rate such that the polymer amount was 1.7 kg / hr. The hydrogenation catalyst (TC) was added to the polymer solution so that the titanium content was 50 ppm based on the charged monomer amount. While adjusting the liquid level in the reactor to 60%, the solution was withdrawn from nozzle D at the bottom of the reactor. At this time, the average residence time τ of the polymer was 70 minutes, and H / D (H: height of the liquid level, D: diameter of the reactor) was 1.3. Thereafter, hydrogen was instantaneously introduced into the reactor from nozzle E at the bottom of the reactor to a pressure of 0.6 MPa, and the supply was immediately stopped. The polymer flowing out from the withdrawal nozzle D of the reactor was sampled every 10 minutes, and the hydrogenation rate was measured. The obtained hydrogenation rate results were plotted against the average residence time τ based on the impulse response method and fitted with the following formula (a), and an approximate value of N = 1.1, which represents the number of completely mixed tanks, was obtained. [Number] Under the above reactor conditions, hydrogen was continuously supplied to a pressure of 0.6 MPa and the reaction was carried out until the hydrogenation rate of the butadiene part reached 82%. Table 5 shows the analysis results of the rubber-like polymer B2 thus obtained by analyzing it by the above method.

[0263] [Example 16] (Polymerization and modification step) Into the first of three continuous stirred tank reactors (CSTR), n-hexane was continuously fed at a flow rate of 5.59 kg / hr, 1,3-butadiene at 0.56 kg / hr, styrene at 0.34 kg / hr, n-butyllithium at 0.55 g / hr, and ditetrahydrofurylpropane as a polar additive at 0.079 g / hr. At this time, the internal temperature of the reactor was maintained at 60°C, and when the polymerization conversion rate reached 70%, the polymer was transferred from the first reactor to the second reactor through the transfer pipe. Next, the temperature of the second reactor was maintained at 60°C, and n-hexane at 0.065 kg / hr, 1,3-butadiene at 0.097 kg / hr, and ditetrahydrofurylpropane as a polar additive at 1.06 g / hr were continuously fed into the second reactor to participate in the reaction. When the polymerization conversion rate reached 95% or more, the polymer was transferred from the second reactor to the third reactor through the transfer pipe, and tetraglycidyl-1,3-bis(aminomethyl)cyclohexane (hereinafter also referred to as "N3") as a modifier was fed at a flow rate of 1.02 g / hr, and the reaction was carried out for 30 minutes. A part of the obtained modified rubber-like polymer solution was withdrawn and the solvent was removed by a dryer. (Hydrogenation step) Furthermore, the above hydrogenation catalyst (TC) was added to the rubber-like polymer solution at 50 ppm on a Ti basis per 100 parts by mass of the rubber-like polymer before hydrogenation, and the reaction was carried out at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C until the hydrogenation rate of the butadiene part reached 82 mol%. To the solution of the obtained rubbery polymer, 0.3 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate as an antioxidant and 0.1 g of 4,6-bis(octylthiomethyl)-o-cresol were added per 100 g of the polymer weight. Then, the rubbery polymer solution was dropped into warm water to remove the solvent, and the resulting product was dried using a dryer to obtain a rubbery polymer B3. Table 5 shows the analysis results of the obtained rubbery polymer B3 analyzed by the above method.

[0264] [Example 17] A rubbery polymer B4 was obtained in the same manner as in Example 16, except that the hydrogenation step was changed to the same method as in Example 15. Table 5 shows the analysis results of the obtained rubbery polymer B4 analyzed by the above method.

[0265] [Table 5]

[0266] [Evaluation of compounding physical properties] Using the rubbery polymers shown in Tables 1 to 5 above, rubber compositions containing each rubbery polymer were obtained according to the following formulations. Rubbery polymer: 100 parts by mass (oil-free) Silica (trade name "Ultrasil 7000GR" manufactured by Evonik Degussa, nitrogen adsorption specific surface area 170 m 2 / g): 85.0 parts by mass Carbon black (trade name "Seast 7HM (N234)" manufactured by Tokai Carbon Co., Ltd.): 2.0 parts by mass Silane coupling agent (trade name "Si69", bis(triethoxysilylpropyl)tetrasulfide) manufactured by Evonik Degussa: 6.8 parts by mass S-RAE oil (trade name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation): 40 parts by mass Zinc oxide: 2.4 parts by mass Stearic acid: 1.25 parts by mass Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 3.5 parts by mass Sulfur: 1.0 part by mass Vulcanization accelerator 1 Tetrabenzylthiuram disulfide: 0.5 part by mass Vulcanization accelerator 2 N-(tert-butyl)-2-benzothiazolesulfenamide: 2.5 parts by mass Total: 246.95 parts by mass

[0267] The above materials were kneaded by the following method to obtain a rubber composition. Using a closed kneader (internal volume 0.3 L) equipped with a temperature control device, as the first-stage kneading, under the conditions of a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm, a rubber-like polymer (Samples 1 to 25), a filler (silica, carbon black), a silane coupling agent, a process oil, zinc oxide, and stearic acid were kneaded. At this time, the temperature of the closed mixer was controlled, and the discharge temperature was 145 to 150 °C to obtain each rubber composition (compound).

[0268] Next, as the second-stage kneading, after cooling the compound obtained above to room temperature, an antioxidant was added and kneaded again to improve the dispersion of silica. Also in this case, the discharge temperature of the compound was adjusted to 120 °C by controlling the temperature of the mixer. After cooling, as the third-stage kneading, sulfur, vulcanization accelerator 1, and 2 were added and kneaded on an open roll set at 70 °C. Thereafter, the obtained kneaded product was molded and vulcanized with a vulcanization press at 160 °C for 20 minutes. The rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, the evaluation was carried out by the following method. For each measured value, for the results of Examples 1 to 8, Comparative Example 1 was used as the comparison target, for Example 9, Comparative Example 2 was used as the comparison target, for Example 10, Comparative Example 3 was used as the comparison target, for Examples 11 to 14, Comparative Example 4 was used as the comparison target, and for Examples 15 to 17, Comparative Example 5 was used as the comparison target. The results for the rubber compositions using the rubber-like polymers obtained for each comparison target were indexed with 100 as the reference.

[0269] 〔Evaluation 1, Evaluation 2: Viscoelastic parameters〕 Using a viscoelasticity tester "ARES" manufactured by Rheometric Scientific, the viscoelastic parameter (tanδ) was measured in torsion mode.

[0270] (Evaluation 1) The tanδ measured at 60°C, a frequency of 10 Hz, and a strain of 3% was used as an index for fuel efficiency. The larger the index, the better the fuel efficiency.

[0271] (Evaluation 2) The tanδ measured at 0°C, a frequency of 10 Hz, and a strain of 1% was used as an index for wet grip performance. The larger the index, the better the wet grip performance.

[0272] (Evaluation 3) Using an Akron wear tester (manufactured by Yasuda Seiki Seisakusho), in accordance with JIS K6264-2, the wear amount under a load of 44.4 N and 1000 rotations was measured. The larger the index, the better the wear resistance.

[0273] (Evaluation 4) In accordance with the tensile test method of JIS K6251, using a tensile tester with a thermostat, the tensile strength and elongation were measured at 0°C, and the product of these was indexed as the material strength under a low-temperature environment. The larger the index, the better the material strength under a low-temperature environment.

[0274] As can be seen from Tables 1 to 5, the rubber-like polymers obtained in Examples 1 to 17 were confirmed to have both wet grip performance and wear resistance, and further have high material strength under a low-temperature environment corresponding to wet grip, compared with the rubber-like polymers obtained in Comparative Examples 1 to 5.

Industrial Applicability

[0275] The rubber-like polymer, rubber composition of the present invention, and crosslinked product (e.g., crosslinked rubber composition) obtained using the rubber-like polymer of the present invention can be used, for example, in packings, gaskets, sealing materials, anti-vibration rubbers, vibration isolation rubbers, vibration damping materials, conveyor belts, shoe outsoles and midsoles, automotive weather strips, glass runs, trunk lids, railway vehicle members, aircraft members, waterproof sheets, engine mounts, air springs, rubber gloves, medical and sanitary products, industrial and various-purpose hoses, battery cases, adhesives, wire coatings, window frame rubbers, rubber rollers for OA equipment and textiles, etc., keypads, keyboard covers, underwater glasses, swimming caps, container bags, marine-related parts, indoor floor materials, artificial muscle materials, materials for various industrial products, etc., and have industrial applicability.

Claims

1. The polymer contains two or more structural units selected from the group consisting of structural units represented by the following formulas (1) to (4), and among the structural units, the polymer contains at least a structural unit represented by formula (2): The weight average molecular weight measured by gel permeation chromatography (GPC) is 100,000 or more, In a temperature-dependent tan δ graph obtained from dynamic viscoelastic analysis using a rheometry system (ADVANCED RHEOMETRIC EXPANSION SYSTEM, ARES) measured under the following conditions, the full width at half maximum (FWHM) value of the tan δ peak appearing in the temperature range of -100°C to 100°C is 20°C or more; Rubber-like polymer. 【Chemistry 1】 [The rheometry system uses a rubber-like polymer sample and a dynamic mechanical analyzer, and the measurement is performed in torsion mode under the conditions of a frequency of 10 Hz, a strain of 0.5%, and a heating rate of 5° C. / min.]

2. When the total content of the structural units represented by the formulas (1) to (4) is 100 mol %, The total content of the content C1 of the structure represented by the formula (1) and the content C2 of the structure represented by the formula (2) is 15 mol% or more and 50 mol% or less, The content C3 of the structure represented by the formula (3) is 10 mol% or more and 30 mol% or less, 2. The rubber-like polymer according to claim 1, wherein the content C4 of the structure represented by formula (4) is 35 mol % or more and 65 mol % or less.

3. 3. The rubber-like polymer according to claim 1, wherein the full width at half maximum (FWHM) value of the tan δ peak is 20° C. or more and 80° C. or less.

4. 3. The rubber-like polymer according to claim 1, wherein the tan δ peak appears in the temperature range of -50°C to 20°C.

5. 3. The rubber-like polymer according to claim 1, wherein the content S of aromatic vinyl monomer units is from 25% by mass to 45% by mass.

6. When the total content of the structural units represented by the formulas (1) to (4) is 100 mol %, 3. The rubber-like polymer according to claim 1, wherein the total content of the content C1 of the structure represented by formula (1) and the content C2 of the structure represented by formula (2) is 15 mol% or more and 30 mol% or less, the content C3 of the structure represented by formula (3) is 14 mol% or more and 25 mol% or less, and the content C4 of the structure represented by formula (4) is 45 mol% or more and 60 mol% or less.

7. 3. The rubbery polymer according to claim 1, having a nitrogen atom content of 30 ppm or more based on the total mass of the rubbery polymer.

8. The rubber polymer is a modified rubber polymer modified with a modifier, 3. The rubber-like polymer according to claim 1, wherein the modifier is an alkoxysilane-based compound containing a nitrogen-containing functional group.

9. A rubber composition comprising 100 parts by mass of the rubber-like polymer according to claim 1 or 2 and 0.1 to 200 parts by mass of a filler.

10. The rubber composition according to claim 9 , wherein the filler is a silica-based filler and / or a carbon black-based filler.

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