Rubbery polymer and rubber composition containing same

Abstract

This rubbery polymer: includes two or more structural units selected from the group consisting of structural units represented by specific formulas (1) to (4); includes at least a structural unit represented by formula (2) among the structural units; has a weight-average molecular weight measured by gel permeation chromatography (GPC) of 100,000 or more; and has a difference between the glass transition start temperature (onset, Tg-on) and the glass transition end temperature (offset, Tg-off) of 10-40℃ when measured by differential scanning calorimetry (DSC).

Description

Rubber-like polymer and rubber composition containing same

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

[0002] In recent years, with the demand for improved fuel economy in automobiles, there has been a demand for conjugated diene polymers as rubber materials for tires that have low rolling resistance, excellent abrasion resistance and tensile properties, as well as adjustment stability, as typified by wet skid resistance.

[0003] The basic functions required for automobile tire treads are braking performance on the road surface and abrasion resistance. The rubber material used in tire treads must have excellent braking performance (wet grip performance) not only on dry roads but also on wet roads, and must also be durable and wear-resistant.

[0004] Conventionally, techniques have been proposed for lowering the glass transition temperature of rubber materials in order to lower the glass transition temperature of rubber compositions in order to improve abrasion resistance.

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

[0006] As such, braking performance on wet roads (wet grip performance) and wear resistance are generally in conflict with each other, and improving one performance tends to cause a deterioration in the other. Tire tread rubber is required to resolve this conflict of properties.

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

[0008] Special Publication No. 2023-517122

[0009] However, when braking on a wet road, friction with the road surface places a large stress on the rubber material, which tends to chip off parts of the rubber from the tire. In other words, even greater strength is required of rubber materials in the environment of braking on a wet road.

[0010] Therefore, an object of the present invention is to provide a rubbery polymer that exhibits good abrasion resistance and wet grip while also being able to increase material strength in the temperature range corresponding to wet grip, and a rubber composition containing the same.

[0011] As a result of extensive research to solve the problems of the prior art described above, the present inventors have found that a rubbery polymer that satisfies specific requirements can exhibit good abrasion resistance and wet grip, while also increasing material strength in the temperature range corresponding to wet grip, thereby preventing, for example, chipping from tires, and have thus completed the present invention.

[0012] That is, the present invention is as follows: [1] A rubbery polymer comprising two or more structural units selected from the group consisting of structural units represented by the following formulas (1) to (4), wherein among the structural units, at least a structural unit represented by formula (2) is included, the rubbery polymer has a weight average molecular weight measured by gel permeation chromatography (GPC) of 100,000 or more, and a difference between a glass transition onset temperature (onset, Tg-on) and a glass transition end temperature (offset, Tg-off) measured by differential scanning calorimetry (DSC) of 10°C or more and 40°C or less. [2] The rubbery polymer according to [1], wherein, when the total content of the structural units represented by the formulas (1) to (4) is taken as 100 mol%, the total 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% to 50 mol%, the content C3 of the structure represented by the formula (3) is 10 mol% to 30 mol%, and the content C4 of the structure represented by the formula (4) is 35 mol% to 65 mol%. [3] The rubbery polymer according to [1] or [2], wherein the difference between the glass transition onset temperature (Tg-on) and the glass transition end temperature (Tg-off) is 10°C to 30°C. [4] The rubbery polymer according to any of [1] to [3], wherein the content S of aromatic vinyl monomer units is 1% by mass to 8% by mass. [5] The rubbery polymer according to any one of [1] to [4], wherein, when the total content of the structural units represented by the formulas (1) to (4) is taken as 100 mol%, the total 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% to 30 mol%, the content C3 of the structure represented by the formula (3) is 14 mol% to 25 mol%, and the content C4 of the structure represented by the formula (4) is 50 mol% to 60 mol%. [6] The rubbery polymer according to any one of [1] to [5], wherein the heat of crystallization derived from the crystallization peak measured by differential scanning calorimetry (DSC) is greater than 50 J / g. [7] The rubbery polymer according to any one of [1] to [6], wherein the content of nitrogen atoms is 30 ppm or more based on the total mass of the rubbery polymer. [8] The rubbery polymer according to any one of [1] to [7], wherein the rubbery polymer is a modified rubbery polymer modified with a modifier, and the modifier is an alkoxysilane-based compound containing a nitrogen-containing functional group. [9] A rubber composition comprising 100 parts by mass of the rubbery polymer according to any one of [1] to [8] and 0.1 parts 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.

[0013] According to the present invention, it is possible to provide a rubbery polymer that exhibits good abrasion resistance and wet grip while also being able to increase material strength in the temperature range corresponding to wet grip, and a rubber composition containing the same.

[0014] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the following embodiment is an example for explaining the present invention, and the present invention is not limited to these. In other words, the present invention can be implemented with any modifications within the scope of the gist of the present invention. Note that in this specification, when an expression is expressed using "~" with a numerical value or physical property value before and after it, it is used to include the values ​​before and after it.

[0015] In this specification, the term "monomer" refers to a compound before polymerization, and the term "monomer unit" refers to a structural unit that constitutes a polymer.

[0016] [Rubber Polymer] The rubber polymer of this embodiment comprises 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, at least a structural unit represented by formula (2) is included; the weight average molecular weight measured by gel permeation chromatography (GPC) is 100,000 or more; and the difference between the glass transition onset temperature (onset, Tg-on) and the glass transition end temperature (offset, Tg-off) measured by differential scanning calorimetry (DSC) is 10°C or more and 40°C or less. The rubber-like polymer of this embodiment has such characteristics, and therefore exhibits good abrasion resistance and wet grip, while also being able to increase material strength in the temperature range corresponding to wet grip.

[0017] In the rubber-like polymer of this embodiment, when the total content of the structural units represented by the above formulas (1) to (4) is taken as 100 mol%, the total 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.

[0018] 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, and the raw material thereof is not particularly limited as long as it is the same as the structural unit represented by the structural formula (1).

[0019] When the total content of the structural units represented by the structural formulas (1) to (4) is taken as 100 mol%, the content C1 of the structure represented by the structural formula (1) (hereinafter also referred to simply as "C1") is preferably 0.0 mol% to 3.0 mol%, more preferably 0.0 mol% to 2.8 mol%, and even more preferably 0.0 mol% to 2.6 mol%. When C1 is within the above-mentioned preferred range, the vulcanizate tends to have excellent breaking strength, breaking elongation, and ozone resistance.

[0020] 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, and the raw material thereof is not particularly limited as long as it is the same as the structural unit represented by the structural formula (2).

[0021] When the total content of the structural units represented by the structural formulas (1) to (4) is taken as 100 mol%, the content C2 of the structure represented by the structural formula (2) (hereinafter also referred to simply as "C2") is preferably 15.0 mol% to 50.0 mol%, more preferably 16.0 mol% to 45.0 mol%, even more preferably 17.0 mol% to 40.0 mol%, and particularly preferably 18.0 mol% to 35.0 mol%. When C2 is within the above-mentioned preferred range, the vulcanizate tends to have excellent breaking strength and breaking elongation.

[0022] In the rubber-like polymer of the present embodiment, the structural unit represented by the structural formula (3) corresponds to, for example, a 1,4-cis bond unit and a 1,4-trans bond unit of a conjugated diene compound, and the raw material thereof is not particularly limited as long as it is the same as the structural unit represented by the formula (3).

[0023] When the total content of the structural units represented by the structural formulas (1) to (4) is taken as 100 mol%, the content C3 (hereinafter also referred to simply as "C3") of the structure represented by the structural formula (3) is preferably 10 mol% to 30 mol%, more preferably 11 mol% to 29 mol%, even more preferably 12 mol% to 28 mol%, even more preferably 13 mol% to 27 mol%, and particularly preferably 14 mol% to 25 mol%. When C3 is within the above-mentioned preferred range, crosslinkability tends to be good when the rubber composition described below is prepared.

[0024] Here, the content of 1,4-cis bonds and 1,4-trans bonds is １３ It can be measured using C-NMR, specifically by the method described in the Examples below.

[0025] In addition, in the structural unit represented by the formula (3), the contents of the 1,4-cis bond and the 1,4-trans bond can be controlled within the above-mentioned numerical range by adjusting the type of polymerization initiator described below and the type and addition amount of the polar compound.

[0026] 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 structure obtained by hydrogenating a 1,4-cis bond unit and a 1,4-trans bond unit of a conjugated diene compound, and the raw material thereof is not particularly limited as long as it is the same as the structural unit represented by the formula (4).

[0027] When the total content of each structural unit represented by the structural formulas (1) to (4) is 100 mol%, the content C4 (hereinafter also referred to simply as "C4") of the structure represented by the structural formula (4) is preferably 35 mol% to 65 mol%, more preferably 40 mol% to 64 mol%, even more preferably 43 mol% to 63 mol%, even more preferably 46 mol% to 62 mol%, and particularly preferably 50 mol% to 60 mol%. When C4 is within the above-mentioned preferred range, orientation as described below tends to occur more easily, which tends to result in excellent wet grip properties. In addition, since it behaves like a pseudo-filler in a low-temperature environment corresponding to wet grip, it tends to have excellent material strength.

[0028] When the total content of the structural units represented by the structural formulas (1) to (4) is taken as 100 mol%, the total 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% to 50 mol%, more preferably 15 mol% to 45 mol%, even more preferably 15 mol% to 40 mol%, and particularly preferably 15 mol% to 30 mol%. When the total content of C1 and C2 is within the above-mentioned preferred ranges, the vulcanizate tends to have excellent breaking strength, breaking elongation, and ozone resistance.

[0029] In this embodiment, the contents C1 to C4 of the structural units represented by the structural formulas (1) to (4) are determined by the formulas described in the examples below. １ It can be measured by H-NMR.

[0030] In the rubber-like polymer of this embodiment, the method for controlling the contents C1 to C4 of the structural units represented by the structural formulae (1) to (4) within the preferred ranges is not particularly limited, but examples include a method of controlling the amount of 1,2-vinyl bonds in the copolymer before hydrogenation by adjusting the amount of polar substance added during polymerization or the polymerization temperature, or a method of controlling the hydrogenation rate.

[0031] (Hydrogenation Reaction) The rubber-like polymer of the present embodiment may be a hydrogenated copolymer. In this case, the hydrogenated copolymer can be obtained by hydrogenating (hydrogenating) the conjugated diene moiety described below in the rubber-like polymer, for example.

[0032] The method for hydrogenating the conjugated diene portion of the rubber-like polymer is not particularly limited, and known methods can be used. However, as described in, for example, WO 96 / 05250, JP 2000-053706, WO 2003 / 085010, WO 2019 / 151126, WO 2019 / 151127, WO 2002 / 002663, and WO 2015 / 006179, a preferred method is to polymerize a conjugated diene monomer by anionic polymerization using various additives and under various conditions, copolymerize it with other monomers as needed, and then hydrogenate the resulting polymer.

[0033] The hydrogenation rate of the hydrogenated copolymer is the proportion (molar ratio) of double bonds in the structure derived from the conjugated diene monomer units that have become saturated through a hydrogenation reaction, and can be expressed by the following formula (A) using the contents C1 to C4 of the respective structural units represented by the structural formulas (1) to (4): Formula (A): 100 * (C2 + C4) / (C1 + C2 + C3 + C4)

[0034] The hydrogenation reaction may be carried out by a batch process, a continuous process, or a combination of these processes. A continuous process is preferably used in the hydrogenation reaction, since it tends to cause a distribution in the hydrogenation rate in the resulting polymer, resulting in structural non-uniformity as described below, and thus increasing the difference between the glass transition onset temperature and the glass transition finish temperature.

[0035] When the rubber-like polymer of the present embodiment is a hydrogenated copolymer, the hydrogenation rate thereof is represented by the above-mentioned mathematical formula (A), and the hydrogenation rate (hydrogenation rate) of the structural unit derived from a 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 even more preferably 65% ​​or more and 90% or less.

[0036] The hydrogenation rate can be controlled within the above-mentioned range by adjusting the amount of hydrogen added, the reaction temperature, the reaction time, the type of catalyst, and the amount of catalyst added. In particular, the hydrogenation rate of the structural units derived from the conjugated diene compound can be controlled by the amount of hydrogen added to the structural units derived from the conjugated diene compound.

[0037] The temperature of the hydrogenation reaction is not particularly limited, but is preferably 60 to 105°C, more preferably 70 to 100°C.

[0038] The hydrogenation rate is １ It can be measured by H-NMR.

[0039] Here, it is preferable that the contents C1 to C4 of the structural units represented by the structural formulas (1) to (4) satisfy the following formula (B): 90(%)≦100*C2 / (C1+C2).

[0040] The formula (B) corresponds to, for example, the hydrogenation rate of the 1,2-vinyl bond of a conjugated diene monomer.

[0041] From the viewpoint of gelation suppression, 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.

[0042] 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, for example, the content ratio of 1,2-vinyl bonds of the conjugated diene monomer and butylene structures in which the 1,2-vinyl bonds have been hydrogenated, and corresponds to the amount of 1,2-vinyl bonds in the copolymer before hydrogenation.

[0043] The content of 1,2-vinyl bonds can be controlled by the polymerization temperature during polymerization and the amount of polar compound added, which will be described later. １ When a rubber-like polymer after hydrogenation is used as a sample, the amount of vinyl bonds and the amount of butylene bonds can be measured. １ The content of 1,2-vinyl bonds can be measured by H-NMR.

[0044] Each of the structural units represented by the structural formulas (1) to (4) of the rubber-like polymer of this embodiment is preferably a structural unit derived from a conjugated diene compound (hereinafter also referred to as a "conjugated diene monomer") or a structural unit obtained by hydrogenating such a structural unit.

[0045] The conjugated diene monomer is not particularly limited, but 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 ease of 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.

[0046] From the viewpoint of achieving a good balance between tensile strength and processability, the weight average molecular weight (Mw) of the rubber-like 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, even more preferably 180,000 or more and 800,000 or less, and still more preferably 200,000 or more and 700,000 or less.

[0047] Also, from the viewpoint of adhesion during production and moldability of the rubber bale, the weight average molecular weight (Mw) of the rubber polymer of this embodiment is preferably within the above-mentioned range.

[0048] The weight average molecular weight (Mw) can be controlled within the above range, for example, by adjusting the amount of the polymerization initiator used.

[0049] The weight average molecular weight (Mw) of the rubber-like polymer of this 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.

[0050] The glass transition temperature of the rubbery polymer of this embodiment is not particularly limited, but from the viewpoint of abrasion resistance, it is preferably −50° C. or lower, more preferably −55° C. or lower, and even more preferably −60° C. or lower.

[0051] On the other hand, from the viewpoint of maintaining sufficient wet grip performance for practical use, the glass transition temperature of the rubbery polymer of this embodiment is preferably −90° C. or higher, more preferably −87° C. or higher, and particularly preferably −85° C. or higher.

[0052] The glass transition temperature of the rubbery polymer can be controlled within the above range, for example, by adjusting the value of the above mathematical formula (A), the vinyl bond content, the hydrogenation rate, or the like, or by adjusting the content of the aromatic vinyl monomer unit described below.

[0053] In general, the glass transition temperature of a rubbery polymer tends to increase as the content of aromatic vinyl monomer units described below increases, and also tends to increase as the content of the structural unit represented by structural formula (4) increases. On the other hand, in the case of a hydrogenated rubbery polymer, the glass transition temperature tends to decrease as the proportion of 1,2-vinyl bonds that are hydrogenated increases.

[0054] When the glass transition temperature of the rubbery polymer is controlled to, for example, −60° C. or lower, the content of aromatic vinyl monomer units described below is preferably 8% by mass or lower, the 1,2-vinyl bond content is preferably 20 mol % or higher and 40 mol % or lower, and the hydrogenation rate is preferably 35% or higher and 98% or lower. Furthermore, when a rubbery polymer having a hydrogenation rate of 90% or higher and a glass transition temperature of −60° C. or lower is obtained, the content of aromatic vinyl monomer units is preferably 6% by mass or lower.

[0055] When the glass transition temperature of the rubbery polymer is controlled to, for example, −70° C. or lower, the content of aromatic vinyl monomer units described below is preferably 6% by mass or lower, the amount of 1,2-vinyl bonds is preferably 20 mol % or higher and 40 mol % or lower, and the hydrogenation rate is preferably 35% or higher and 85% or lower.

[0056] When the glass transition temperature of the rubbery polymer is controlled to, for example, −80° C. or lower, the content of aromatic vinyl monomer units described below is preferably 6% by mass or lower, the amount of 1,2-vinyl bonds is preferably 20 mol % or higher and 40 mol % or lower, and the hydrogenation rate is preferably 35% or higher and 70% or lower.

[0057] When the glass transition temperature of the rubbery polymer is within the above preferred range, the rubber composition obtained using the rubbery polymer tends to have an excellent balance between abrasion resistance and wet grip performance.

[0058] The glass transition temperature is measured in accordance with ISO 22768:2006 by recording a differential scanning calorimetry curve (DSC curve) while raising the temperature from -100°C at 10°C / min in a nitrogen flow of 50 mL / min, and determining the peak top (inflection point) attributable to the glass transition in the obtained DSC differential curve. Specifically, the glass transition temperature can be measured by the method described in the examples below.

[0059] Furthermore, in the rubbery polymer of this embodiment, the difference between the temperature at which the glass transition begins, i.e., the glass transition onset temperature (onset, Tg-on), and the temperature at which the glass transition ends, i.e., the glass transition end temperature (offset, Tg-off), in the DSC curve obtained here is from 10° C. to 40° C. By controlling the difference between the glass transition onset temperature and the glass transition end temperature of the rubbery polymer to be from 10° C. to 40° C., a rubbery polymer excellent in tensile properties and running resistance, as well as in wet skid resistance and abrasion resistance can be obtained.

[0060] The rubbery polymer of this embodiment has two or more structures selected from the group consisting of structures represented by the structural formulas (1) to (4), and tends to have a wider difference between the glass transition onset temperature and the glass transition end temperature than conventional rubbery polymers. The reason for this is not clear, but it can be broadly divided into two types depending on the structure of the rubbery polymer: (i) a case where the difference is caused by structural non-uniformity, and (ii) a case where the difference is caused by the orientation of the component of the structural formula (4), or a combination thereof.

[0061] In the case of (i) where the problem is caused by structural non-uniformity, when the rubbery polymer exhibits an intramolecularly uniform structure, the glass transition onset temperature and glass transition end temperature are substantially the same as the glass transition temperature and fall within a range of less than ±10° C. from the glass transition temperature, and therefore the difference between the onset temperature and end temperature tends to be no more than 10° C. However, because the rubbery polymer of this embodiment has intramolecular structural non-uniformity, the difference between the glass transition onset temperature and the glass transition end temperature is greater than or equal to 10° C. and less than or equal to 40° C., resulting in excellent wet skid resistance and abrasion resistance.

[0062] The method for obtaining such a rubbery polymer having heterogeneity is not particularly limited, but possible methods include, for example, a method of hydrogenating a rubbery polymer or a copolymer of a rubbery polymer and an aromatic vinyl compound, the difference between the glass transition onset temperature and the glass transition end temperature of which is 10°C or more and 40°C or less, by the method described below, or a method of hydrogenating a rubbery polymer or a copolymer of a rubbery polymer and an aromatic vinyl compound, thereby producing components of the structural formulas (1) to (4) each having a different glass transition temperature within the same molecule by providing a distribution in the hydrogenation rate.

[0063] On the other hand, in the case of (ii), even after the glass transition point is reached, the components of structural formula (4) are oriented, restricting molecular motion, and therefore the glass transition end temperature shifts to a higher temperature, which is thought to result in an increase in the difference between the glass transition onset temperature and the glass transition end temperature.

[0064] Here, the component of structural formula (4) tends to have a larger difference between the glass transition onset temperature and the glass transition end temperature because the longer the repeating unit, the more pronounced the influence of orientation becomes.

[0065] The method for obtaining a rubber polymer having a wide difference between the glass transition onset temperature and the glass transition end temperature due to the orientation of the component of structural formula (4) is not particularly limited, but examples thereof include a method in which 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 component of structural formula (4), and a method in which the ratio of the component of structural formula (4) is increased to increase the component that orients after the glass transition temperature is reached.

[0066] Furthermore, the rubbery polymer of this embodiment has higher strength as a rubber material than rubbery polymers that show equivalent DSC curves in the vicinity of the temperature range corresponding to wet grip, and is less likely to chip when applied to a tire tread.

[0067] Although the reason for this is unclear, it is believed that the rubber polymer of this embodiment contains the component of structural formula (4) having orientation in its molecule, and therefore the relaxation of the component whose molecular motion is constrained by this orientation contributes to the DSC curve. The component whose molecular motion is constrained due to such orientation behaves as a filler, and as a result, the rubber polymer exhibits higher strength than rubber polymers having equivalent DSC curves around the temperature corresponding to wet grip.

[0068] When the difference between the glass transition onset temperature and the glass transition end temperature of the rubbery polymer of this embodiment is 10° C. or more, the effect of simultaneously improving wet skid resistance and abrasion resistance can be realized, and when the difference between the glass transition onset temperature and the glass transition end temperature is 40° C. or less, processability and tensile properties are improved. Therefore, the rubbery polymer of this embodiment has a difference between the glass transition onset temperature and the glass transition end temperature of 10° C. or more and 40° C. or less, and to optimally realize the above-mentioned effects, it is preferable that the difference be 10° C. or more and 30° C. or less.

[0069] The rubbery polymer of this embodiment may contain a structural unit derived from an aromatic vinyl compound (hereinafter also referred to as an "aromatic vinyl monomer").

[0070] The aromatic vinyl compound is not particularly limited, but examples thereof include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of industrial availability. These compounds may be used alone or in combination of two or more.

[0071] Furthermore, the rubber-like polymer of this embodiment is preferably a hydrogenated product of a copolymer of a conjugated diene compound and an aromatic vinyl compound (hereinafter also referred to as a "conjugated diene-aromatic vinyl copolymer").

[0072] In the rubber-like polymer of this embodiment, the content of aromatic vinyl monomer units is preferably 1.0% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2.0% by mass or more, from the viewpoints of breaking strength and tear strength of the vulcanizate. On the other hand, from the viewpoints of crosslinkability and abrasion resistance when vulcanized, the content of aromatic vinyl monomer units is preferably 8.0% by mass or less, more preferably 7.5% by mass or less, even more preferably 7.0% by mass or less, and particularly preferably 6.5% by mass or less.

[0073] The content of aromatic vinyl monomer units in the rubbery polymer of this embodiment can be controlled within the above numerical range, for example, by adjusting the amount of aromatic vinyl monomer added in the polymerization step.

[0074] Here, the content of the aromatic vinyl monomer unit is １ It can be measured using H-NMR, specifically in accordance with the method described in the Examples below.

[0075] When the rubber-like polymer of the present embodiment is a hydrogenated product of a conjugated diene-aromatic vinyl copolymer, it is preferable that the proportion of aromatic vinyl monomer units present alone is high from the viewpoint of improving abrasion resistance.

[0076] The content of the aromatic vinyl monomer block in the rubbery polymer of this 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, even 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 rubbery polymer of this embodiment is not particularly limited, but is, for example, 0.1% by mass or more. In this specification, the term "aromatic vinyl monomer block" refers to a structure in which eight or more aromatic vinyl monomer units are chained.

[0077] The method for measuring the aromatic vinyl monomer block is not particularly limited, and examples thereof include known methods such as measuring the chain of styrene units using NMR as described in WO 2014 / 133097. Another method includes a method in which a rubbery polymer before hydrogenation is used as a sample, the polymer is decomposed by the Kolthoff method (the method described in I. M. KOLTHOFF, et al., J. Polym. Sci. 1, 429 (1946)), and the amount of polystyrene insoluble in methanol is analyzed.

[0078] In the rubbery polymer of this embodiment, the presence of a small amount of aromatic vinyl monomer block results in the generation of locally high glass transition temperature regions, which tends to increase the difference between the glass transition onset temperature (onset, Tg-on) and the glass transition end temperature (offset, Tg-off) as measured by differential scanning calorimetry (DSC). However, when the content of the aromatic vinyl monomer block is equal to or less than the upper limit, separation between the aromatic vinyl monomer block-containing region and the aromatic vinyl monomer block-free region can be suppressed, and phase separation of the rubbery polymer tends to be suppressed. From this perspective, the content of the aromatic vinyl monomer block in the rubbery polymer of this embodiment is preferably in the above-mentioned range.

[0079] The aromatic vinyl monomer block content in the rubbery polymer of this embodiment can be controlled within the above-mentioned range by adjusting the method of adding the aromatic vinyl compound, the amount of polymerization aid added, the polymerization temperature, etc.

[0080] The rubbery polymer of this embodiment preferably has microcrystalline properties. As an index of microcrystalline properties, the heat of crystallization of the crystallized portion can be measured using differential scanning calorimetry (hereinafter also referred to as "DSC"). The heat of crystallization of the rubbery polymer of this embodiment is preferably greater than 50 J / g. From the viewpoint of reducing hardness at low temperatures and exhibiting good wet grip performance due to the orientation caused by the structure represented by formula (4), the heat of crystallization of the rubbery polymer of this embodiment is more preferably 51 J / g or more, even more preferably 52 J / g or more, and particularly preferably 53 J / g or more. On the other hand, from the viewpoint of suppressing precipitation from the solvent during polymerization, the heat of crystallization of the rubbery polymer of this embodiment is preferably 65 J / g or less, more preferably 64 J / g or less, even more preferably 63 J / g or less, and particularly preferably 62 J / g or more. The heat of crystallization of the rubber-like polymer is determined from the peak area attributable to crystallization in the DSC differential curve obtained by recording a DSC curve while decreasing the temperature within a predetermined temperature range in accordance with ISO 22768: 2006. Specifically, it can be measured by the method described in the examples below.

[0081] The heat of crystallization of the rubber-like polymer can be controlled within the above range by adjusting the aromatic vinyl monomer unit content, the value of the formula (A), the vinyl bond content, the hydrogenation rate, etc. In particular, the heat of crystallization tends to increase as the content of the structural unit represented by the structural formula (1) or the structural unit represented by the structural formula (2) decreases and the content of the structural unit represented by the structural formula (4) increases. Specifically, although not particularly limited, for example, when the content of the aromatic vinyl monomer unit is 2% by mass and the total content of the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (2) is 26 mol%, the content of the structural unit represented by the structural formula (4) is preferably 50 mol% or more and 65 mol% or less.

[0082] The rubber-like polymer of this embodiment may have one peak (unimodal) or two or more peaks in a molecular weight distribution curve obtained by GPC measurement, and the 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 but less than 1.7.

[0083] Generally, continuous polymerization produces a unimodal polymer with a broad molecular weight distribution, resulting in excellent processability but poor tensile and viscoelastic properties, while batch polymerization produces a bimodal polymer with a narrow molecular weight distribution, resulting in excellent tensile and viscoelastic properties but poor processability and low productivity. However, by applying the production method described below according to one embodiment of this invention, it is possible to selectively narrow the molecular weight distribution to the maximum extent possible despite the continuous production, thereby making it easy to control the balance of physical properties between processability and tensile and viscoelastic properties.

[0084] When the rubbery polymer of the present embodiment is a hydrogenated rubbery polymer obtained by hydrogenating a rubbery polymer having a wide molecular weight distribution, a distribution occurs in the length of the structural formula (4), and the components of the structural formula (4) are oriented, thereby obtaining a rubbery polymer having a wide difference between the glass transition onset temperature and the glass transition end temperature, which is preferable.

[0085] The rubbery polymer according to this embodiment may have a silicon atom (Si) and nitrogen atom (N) content of 30 ppm or more, or 30 ppm to 1000 ppm, based on the total mass of the rubbery polymer. Furthermore, the lower limit of the silicon atom (Si) and nitrogen atom (N) content of the rubbery polymer according to this embodiment may be preferably 50 ppm or more, or 100 ppm or more, based on the total mass of the rubbery polymer. Meanwhile, the upper limit of the silicon atom (Si) and nitrogen atom (N) content of the rubbery polymer according to this embodiment may be preferably 700 ppm or less, or more preferably 500 ppm or less, based on the total mass of the rubbery polymer. When the silicon atom (Si) and nitrogen atom (N) contents are within the above ranges, the rubber composition containing the rubbery polymer tends to have excellent mechanical properties, such as tensile properties and viscoelastic properties. Meanwhile, the Si and N may be derived from a compound having a modifying functional group, such as a modifier, a modification initiator, or a modifying monomer, which is described below, when the compound is introduced.

[0086] The Si and N contents can be controlled within the above numerical ranges, for example, by adjusting the amounts and types of coupling agents and modifiers having nitrogen atom-containing groups, which will be described later.

[0087] The rubbery polymer of this embodiment is preferably a modified rubbery polymer modified with a modifying agent. Specifically, the rubbery polymer of this embodiment is preferably a modified rubbery polymer obtained by, for example, performing a modification reaction with a reactive compound (hereinafter also referred to as a "modifying agent") on the active terminal of a copolymer obtained through a polymerization step and, if necessary, a branching step using a branching agent.

[0088] In the modification step in which a modification reaction is carried out using a modifier, one of the active ends of the rubber-like polymer is modified with a predetermined modifier to obtain a modified rubber-like polymer.

[0089] The rubbery polymer of this embodiment preferably contains nitrogen atoms. The rubbery polymer containing nitrogen atoms can be obtained, for example, by carrying out a modification reaction using a modifier having a nitrogen atom-containing group described below. The nitrogen atom content in the rubbery polymer of this embodiment is as described above.

[0090] When a rubber-like polymer coupled with a modifier having a nitrogen atom-containing group is compounded into a rubber composition containing a filler, the dispersibility of fillers such as silica and carbon black is improved, the processability of the rubber composition containing the filler is good, and when the rubber composition is vulcanized, the abrasion resistance and breaking strength are good.

[0091] As the nitrogen atom-containing modifying agent, from the viewpoints of polymerization productivity and a high modification rate, an isocyanate compound, an isothiocyanate compound, an isocyanuric acid derivative, a carbonyl compound containing a nitrogen-containing functional group (hereinafter also referred to as "nitrogen group-containing"), a nitrogen group-containing vinyl compound, a nitrogen group-containing epoxy compound, a nitrogen group-containing alkoxysilane compound, and the like are preferred.

[0092] Furthermore, from the viewpoint of improving the reduction in viscosity of a crosslinked product (e.g., a crosslinked rubber composition) obtained using the rubber-like polymer of this embodiment and the reduction in cracking of a compound sheet, it is preferable to use a modifier (hereinafter referred to as "coupling agent") that can obtain a branched structure simultaneously with the modification reaction. The higher the number of branches of the coupling agent, the more preferable. 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.

[0093] As these nitrogen atom-containing coupling agents, nitrogen group-containing alkoxysilane compounds and nitrogen group-containing polyfunctional modifiers are preferred from the viewpoint of reactivity.

[0094] Examples of the nitrogen group-containing alkoxysilane compound 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- 2-Methoxy,2-methyl-1-(3-trimethoxysilylpropyl)-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, 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-azacyclopentane],

[0033] tetrakis(3-trimethoxysilylpropyl)-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.

[0095] Examples of nitrogen group-containing polyfunctional modifiers 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 epithio 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 which have at least one nitrogen atom in the compound.

[0096] In calculating the number of moles of functional groups, an alkoxy group per epoxy group, carbonyl group, epithio group, thiocarbonyl group, imino group, ethyleneimino group, halogen group, conjugated diene group, arylvinyl group, or alkoxysilyl group should be counted as monofunctional; a carboxylic acid ester group, a carboxylic acid amide group, an acid anhydride group, a thiocarboxylic acid ester group, a dithiocarboxylic acid ester group, a thiocarboxylic acid amide group, an isocyanate group, or a thioisocyanate group should be counted as difunctional; and a phosphate ester group or a phosphite ester group should be counted as trifunctional.

[0097] The polyfunctional modifier that can be preferably used to modify the rubber-like polymer of this embodiment is one in which the sum of the numbers of the above-mentioned functional groups in one molecule is 2 or more, and more preferably one in which the sum of the numbers of the functional groups is 3 or more.

[0098] When the rubbery polymer of the present embodiment is a hydrogenated rubbery polymer, in addition to the coupling agents and modifiers described above, polyfunctional modifiers described below and coupling agents not containing nitrogen atoms can also be used.

[0099] Examples of polyfunctional modifiers 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; diglycidyl Examples of suitable compounds include glycidylamino compounds such as aniline, diglycidyl orthotoluidine, tetraglycidyl meta-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; and 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.

[0100] Furthermore, examples of coupling agents that do not contain nitrogen atoms 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, monomethyltrichlorosilicon, monoethyltrichlorosilicon, monobutyltrichlorosilicon, monohexyltrichlorosilicon, monomethyltribromosilicon, and bistrichlorosilylethane; and alkoxyhalogenated silane compounds such as monochlorotrimethoxysilane, monobromotrimethoxysilane, dichlorodimethoxysilane, dibromodimethoxysilane, trichloromethoxysilane, and tribromomethoxysilane.

[0101] Further, examples of coupling agents that do not contain a nitrogen atom include halogenated tin compounds such as tin tetrachloride, tin tetrabromide, monomethyltrichlorotin, monoethyltrichlorotin, monobutyltrichlorotin, monophenyltrichlorotin, and bistrichlorostannylethane; polyhalogenated phosphorus compounds such as trichlorophosphine and tribromophosphine; phosphite compounds such as trisnonylphenylphosphite, trimethylphosphite, and triethylphosphite; and phosphate compounds such as trimethylphosphate and triethylphosphate.

[0102] Furthermore, a terminal modifying agent may be used as a modifying agent for modifying the rubbery polymer of this embodiment. Examples of the terminal modifying agent 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, and 1,3-dihydro-1,3-dimethyl-2H-imidazol-2-one.

[0103] In this specification, unless otherwise specified, the "modification ratio" represents the mass ratio of the polymer having a nitrogen atom-containing functional group to the total amount of the rubber-like polymer.

[0104] For example, when a nitrogen atom-containing modifying agent is reacted with the terminal end of a polymer, the mass ratio of the polymer having a nitrogen atom-containing functional group due to the nitrogen atom-containing modifying agent to the total amount of the polymer is expressed as the modification rate.

[0105] On the other hand, when a polymer is branched using a branching agent containing a nitrogen atom, the resulting copolymer will have a nitrogen atom-containing functional group, and therefore this branched polymer will also be counted when calculating the modification rate.

[0106] That is, in this specification, the total mass ratio of a coupling polymer formed by a modifying agent having a nitrogen atom-containing functional group and / or a branched polymer formed by a branching agent having a nitrogen atom-containing functional group is the "modification rate."

[0107] From the viewpoint of a balance among processability, abrasion resistance, breaking strength, and compression set, the rubbery polymer of the present embodiment preferably has a modification rate measured by a column adsorption GPC method (hereinafter also simply referred to as "modification rate") of 5% or more and 99% or less, based on the total amount of the rubbery polymer.

[0108] The modification rate is more preferably 10% or more, even 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.

[0109] The degree of modification can be measured, for example, by chromatography, which can separate functional group-containing modified components from unmodified components.

[0110] Examples of such methods using chromatography include a method in which a gel permeation chromatography column is used, packed with a polar substance such as silica that adsorbs specific functional groups, and the non-adsorbed components are quantitatively determined using an internal standard for comparison (column adsorption GPC method).

[0111] More specifically, the modification rate can be determined by measuring the amount of adsorption onto the silica column from the difference between a chromatogram obtained by measuring a sample solution containing a sample and a low-molecular-weight internal standard polystyrene on a polystyrene gel column and a chromatogram obtained by measuring the sample solution on a silica column.

[0112] More specifically, the modification rate can be measured by the method described in the Examples.

[0113] In the rubber-like polymer of this embodiment, the modification rate can be controlled, for example, by adjusting the amount of modifier added and the reaction method, and can thereby be controlled to 5% or more and 99% or less.

[0114] For example, the above-mentioned modification rate can be achieved by combining a method of polymerization using an organolithium compound having at least one nitrogen atom in the molecule as a polymerization initiator, which will be described later, a method of copolymerizing a monomer having at least one nitrogen atom in the molecule, and a method of using a modifying agent having a structural formula as will be described later, and controlling the polymerization conditions.

[0115] Furthermore, by modifying the polymerization initiation terminal with an amine, the ratio of modified polymer in the rubbery polymer can also be adjusted. The method for modifying the polymerization initiation terminal of the conjugated diene portion of the rubbery polymer with an amine is not particularly limited, and known methods can be used. For example, as described in JP-A-2018-16678, a preferred method involves adding an organolithium compound as a polymerization initiator in the presence of an amine compound having active hydrogen to obtain a polymer chain having a nitrogen atom at the molecular end. Examples of amine compounds having active hydrogen include piperidine, hexamethylene, azacyclooctane, 1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, 1,2,3,6-tetrahydropyridine, and 3,5-dimethylpiperidine.

[0116] The Mooney viscosity (ML) of the rubbery polymer of this embodiment at 100°C when using an L-type rotor １＋４ From the viewpoint of processability and compression set, the tensile strength 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.

[0117] The Mooney viscosity of the rubbery polymer of this embodiment can be measured by the method described in the Examples below.

[0118] The Mooney viscosity (ML) of the rubber polymer at 100°C using an L-type rotor １＋４ ) can be controlled, for example, by the molecular weight of the rubber-like polymer, the hydrogenation rate, etc. 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.

[0119] Furthermore, since the Mooney viscosity of a rubbery polymer tends to increase as the hydrogenation rate increases, when the hydrogenation rate of the rubbery polymer is set to 70% or more, it is preferable that the weight average molecular weight Mw of the rubbery polymer be 100,000 or more and 500,000 or less, and when the hydrogenation rate of the rubbery polymer is 50% or less, it is preferable that the weight average molecular weight Mw of the rubbery polymer be 200,000 or more and 800,000 or less.

[0120] The rubbery polymer of the present embodiment may be a rubbery polymer obtained by reacting the active terminal of a polymer obtained through a polymerization step and, if necessary, a branching step with a modifier or a coupling agent, and then subjecting the resulting polymer to a hydrogenation step.

[0121] When titanium is used as a hydrogenation catalyst component in the production of the rubbery polymer of this embodiment, the amount of titanium added is preferably 150 ppm or less based on the rubbery polymer before hydrogenation.

[0122] In the rubbery polymer of this embodiment, the titanium content is preferably 1 ppm to 100 ppm, more preferably 5 ppm to 90 ppm, and even more preferably 10 ppm to 80 ppm. A titanium content of 100 ppm or less can prevent yellow coloration of the rubbery polymer, while a titanium content of 1 ppm or more can eliminate the need for removal equipment, thereby reducing costs.

[0123] When aluminum is used as a hydrogenation catalyst component in producing the rubbery 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 no aluminum is added, relative to the rubbery polymer before hydrogenation.

[0124] From the viewpoint of reducing the safety of the catalyst during the hydrogenation reaction, the aluminum content of the rubbery polymer of this embodiment is preferably 2 ppm or less, more preferably 1 ppm or less, and even more preferably contains no aluminum. Furthermore, by using lithium or magnesium instead of aluminum, the function of aluminum as a co-catalyst can be complemented.

[0125] Furthermore, from the viewpoints of suppressing an increase in Mooney viscosity (ML viscosity) and of the ease of handling and safety of the hydrogenation catalyst, the hydrogenation catalyst added during the production of the hydrogenated rubbery polymer preferably contains 0.05 mol or less of aluminum per mol of titanium, more preferably 0.04 mol or less of aluminum, even more preferably 0.03 mol or less of aluminum, and particularly preferably contains no aluminum.

[0126] By adjusting the titanium content and aluminum content in the hydrogenation catalyst, the titanium content and aluminum content of the hydrogenated rubbery polymer can be controlled within the above numerical ranges.

[0127] The rubbery polymer of this embodiment is preferably obtained by carrying out a polymerization step using a predetermined polymerization initiator, followed by a coupling reaction step preferably using the above-mentioned coupling agent, followed by a hydrogenation step, and more preferably by carrying out a branching step using a branching agent before the coupling reaction step.

[0128] (Polymerization Step) As the polymerization initiator used in the polymerization step, at least an organic monolithium compound can be used.

[0129] The organomonolithium compound is not limited to the following, but examples thereof include low molecular weight compounds and solubilized oligomeric organomonolithium compounds.

[0130] Furthermore, examples of the organic monolithium compound include compounds having a carbon-lithium bond, a nitrogen-lithium bond, and a tin-lithium bond in terms of the bonding mode between the organic group and the lithium.

[0131] The amount of the organic monolithium compound used as the polymerization initiator is preferably determined depending on the structure of the target copolymer and the molecular weight of the copolymer.

[0132] The amount of a monomer such as a conjugated diene compound used relative to the amount of a polymerization initiator used is related to the degree of polymerization, that is, tends to be related to the number average molecular weight and / or weight average molecular weight.

[0133] Therefore, in order to increase the molecular weight, it is advisable to adjust the amount of polymerization initiator used in a direction to decrease it, and in order to decrease the molecular weight, it is advisable to adjust the amount of polymerization initiator used in a direction to increase it.

[0134] As the organic monolithium compound, an alkyllithium compound having a substituted amino group or a dialkylaminolithium is preferred from the viewpoint that it can be used as one method for introducing nitrogen atoms into a rubbery polymer.

[0135] In this case, a copolymer having a nitrogen atom consisting of an amino group at the polymerization initiation terminal can be obtained.

[0136] The substituted amino group is an amino group that does not have an active hydrogen or has a structure in which the active hydrogen is protected.

[0137] Examples of alkyllithium compounds having an amino group that does not have an active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium.

[0138] Examples of alkyllithium compounds having an amino group with a structure in which an active hydrogen is protected include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0139] Examples of dialkylaminolithiums include, but are not limited to, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, lithium-di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.

[0140] These organomonolithium compounds having a substituted amino group can also be used as solubilized oligomeric organomonolithium compounds by reacting them with a small amount of a polymerizable monomer, such as 1,3-butadiene, isoprene, or styrene.

[0141] The organic monolithium compound is preferably an alkyllithium compound from the viewpoints of industrial availability and ease of control of the polymerization reaction, in which case a copolymer having an alkyl group at the polymerization initiation terminal can be obtained.

[0142] Examples of the alkyllithium compound include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium.

[0143] As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoints of industrial availability and ease of control of the polymerization reaction.

[0144] These organomonolithium compounds may be used alone or in combination of two or more, and may also be used in combination with other organometallic compounds.

[0145] Examples of the other organometallic compounds include alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds.

[0146] Alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds, as well as alkaline earth metal alkoxides, sulfonates, carbonates, and amides.

[0147] Examples of organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Examples of other organometallic compounds include organoaluminum compounds.

[0148] In the polymerization step, the polymerization reaction mode is not limited to the following modes, but examples thereof include a batch mode (also called a "batch mode") and a continuous mode.

[0149] In the continuous system, one or more connected reactors can be used. The continuous reactor is not particularly limited, but for example, a tank type or a tubular type equipped with a stirrer can be used. In the continuous system, preferably, the monomer, the inert solvent, and the 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.

[0150]

[0023] When a continuous process is used as the method for producing a rubbery polymer according to the present embodiment, it is not particularly limited, but may include, for example, step (S1) of polymerizing a conjugated diene monomer, or a conjugated diene monomer and an aromatic vinyl monomer, in the presence of a hydrocarbon solvent, a polymerization initiator, and a polar additive (described below) to produce an activated polymer, and step (S2) of reacting the activated polymer produced in step (S1) with a modifier. Step (S1) may be continuously carried out in two or more polymerization reactors, and when the polymerization conversion rate of the first reactor is 70% to 85%, the activated polymer may be transferred to the second reactor, and a polar additive, or a polar additive and a conjugated diene monomer, may be additionally added to the second reactor. This production method can produce a rubbery polymer in which segments with different glass transitions derived from each step are linked, resulting in a rubbery polymer with a wide difference between the glass transition onset temperature and the glass transition end temperature.

[0151] In the above-described manufacturing method, step (S1) may be, for example, an anionic polymerization step in which a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer are polymerized. Specifically, step (S1) may be living anionic polymerization, which has an anionic active site at the polymerization terminal through an anionic growth polymerization reaction. The polymerization in step (S1) may be temperature-rise polymerization, isothermal polymerization, or constant-temperature polymerization (adiabatic polymerization). The constant-temperature polymerization refers to a polymerization method in which polymerization is performed using the heat of reaction itself without adding heat after adding a polymerization initiator. The temperature-rise polymerization refers to a polymerization method in which heat is added after adding the polymerization initiator to increase the temperature. The isothermal polymerization refers to a polymerization method in which the temperature of the polymer is maintained constant by adding heat or removing heat after adding the polymerization initiator.

[0152] In addition, in one embodiment of the method for producing a rubbery polymer according to the present invention, the polymerization in step (S1) may be carried out using a diene compound having 1 to 10 carbon atoms in addition to the conjugated diene monomer, which tends to prevent gel formation on the reactor wall during long-term operation. The diene compound is not particularly limited, but may be 1,2-butadiene, for example.

[0153] In one embodiment of the method for producing a rubbery polymer according to the present invention, the polymerization in step (S1) may be carried out in two or more polymerization reactors, and the polymerization conversion rate in the first polymerization reactor among the polymerization reactors may be 70% to 85%, or 70% to 80%. That is, in step (S1), the polymerization is preferably carried out until the polymerization conversion rate in the first polymerization reactor is 70% or more, 70% to 85%, or 70% to 80%.

[0154] 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 the microstructure of the polymer is easily controlled during polymerization, which tends to widen the difference between the glass transition onset temperature and the glass transition end temperature.

[0155] The polymerization in the first reactor may be carried out at a temperature range of, but is not particularly limited to, 80° C. or less, −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 narrow, and physical properties tend to be improved.

[0156] According to one embodiment of the method for producing a rubbery polymer according to the present invention, step (S1) is carried out in two or more reactors. After polymerization is carried out in the first reactor until the aforementioned polymerization conversion rate is reached, the polymerization product is transferred to the second reactor, and a polar additive or a conjugated diene monomer is additionally introduced into the second reactor.

[0157] In this case, the polar additive or the polar additive or the conjugated diene monomer to be added may be added simultaneously or sequentially, and may be added at a single point within the above-mentioned polymerization conversion rate range, or may be added in portions at multiple points within the above-mentioned range, or may be added continuously within the above-mentioned range.

[0158] The addition of a polar additive or a polar additive and a conjugated diene monomer can be a means of controlling the polymerization conversion rate in the first reactor and realizing the glass transition temperature characteristics of the rubbery polymer produced, because the addition of a polar additive can further add power to the polymerization reaction after a certain polymerization conversion rate, causing microstructural deformation.

[0159] In particular, the polar additive can control the ratio of 1,2-bonds and 1,4-bonds by controlling the reaction rate when homopolymerizing a conjugated diene monomer, and tends to induce the easy formation of a random copolymer by correcting the difference in reaction rate between these monomers when copolymerizing a conjugated diene monomer and an aromatic vinyl monomer.

[0160] In this case, the additional polar additive may be used in an appropriate amount so as to widen the full width at half maximum of the tan δ peak. For example, the additional polar additive may be used in an amount 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 of the total monomers used for initiating polymerization.

[0161] The additional conjugated diene monomer 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 monomers used for initiating polymerization. When the amounts of the additional polar additive and conjugated diene monomer are controlled within the above ranges, the glass transition temperature of the polymer is easily controlled and more precise adjustment is possible, which tends to increase the difference between the glass transition onset temperature and the glass transition end temperature.

[0162] The total amount of polar additive used in the polymerization of step (S1) may be preferably 0.001 g to 50 g, or 0.002 g to 1.0 g, based on 100 g of total monomers. In another example, the total amount of polar additive used 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 total polymerization initiators. Here, the total amount of polar additive used refers to the content including additional polar additives.

[0163] The polymerization in the second reactor is not particularly limited, and may be carried out at a temperature range of, for example, 80° C. or less, −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 tends to be narrow, and physical properties tend to be improved.

[0164] Meanwhile, in addition, in controlling the full width at half maximum of the tan δ peak obtained from the dynamic viscoelasticity analysis, the polymerization temperatures in the first and second reactors may also have an effect. In this case, it is 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 it is preferable that the polymerization temperature of the second reactor is 60° C. or higher.

[0165] Meanwhile, the polymerization conversion rate is not particularly limited, but for example, it may be determined by measuring the solid concentration in a polymer solution containing a polymer during polymerization. A specific example is not particularly limited, but for example, in order to secure the polymer solution, a cylindrical container is attached to the outlet of each polymerization reactor, a certain amount of polymer solution is filled into the cylindrical container, the cylindrical container is separated from the reactor, and the weight (A) of the cylinder filled with the polymer solution is measured. Thereafter, the polymer solution filled in the cylindrical container is transferred to an aluminum container, for example, an aluminum dish, and the weight (B) of the cylindrical 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 the weight (C) of the dried polymer is measured, and then the polymerization conversion rate may be calculated according to the following Equation 1:

[0166]

[0167] In Equation 1, the total solids content is the total solids content (monomer content) in the polymer solution separated from each reactor, and is expressed as a mass percentage of solids relative to 100% of the polymer solution. For example, if the total solids content is 20% by mass, it may be calculated by substituting 20 / 100, i.e., 0.2, into Equation 1.

[0168] Meanwhile, the polymer polymerized in the second reactor may be sequentially transferred to a final polymerization reactor and polymerization may be continued until a final polymerization conversion rate of 95% or more is reached. After polymerization in the second reactor, the polymerization conversion rate of each reactor may be adjusted appropriately for each reactor, or from the third reactor to the final polymerization reactor, to control the molecular weight distribution. A reaction terminator may then be added to deactivate the active sites. If a modified rubber-like polymer is to be produced, the activated polymer may be transferred to a modification reaction step. The reaction terminator may be any material commonly used in the art, without limitation. The activated polymer produced in step (S1) may refer to a polymer in which a polymer anion and an organometallic cation of a polymerization initiator are combined.

[0169] Step (S2) is a modification step in which the activated polymer prepared in step (S1) is reacted with a modifier, whereby the anionic active site of the activated polymer reacts 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 total monomers. Alternatively, 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 mole of the polymerization initiator used in step (S1).

[0170] According to one embodiment of the method for producing a rubbery polymer according to this embodiment, the modifier may be introduced into a modification reactor, and step (S2) may be performed in the modification reactor. Alternatively, the modifier may be introduced into a transfer section for transferring the activated polymer produced in step (S1) to a modification reactor for performing step (S2), and a reaction may be performed by mixing the activated polymer and the modifier in the transfer section. In this case, the reaction may be a modification reaction in which the modifier is simply bonded to the activated polymer, or a coupling reaction in which the activated polymer is linked to the modifier.

[0171] Meanwhile, the method for preparing the modified rubbery polymer may further include a step of adding a conjugated diene monomer to the activated polymer prepared in step (S1) and reacting the added monomer with the activated polymer before the modification reaction in step (S2), which is advantageous for the subsequent modification reaction. In this case, the conjugated diene monomer may be added in an amount of 1 to 100 moles per mole of the activated polymer.

[0172] The method for producing a modified rubbery polymer according to one embodiment of the method for producing a rubbery polymer according to the present embodiment is a method that can satisfy the characteristics of the modified rubbery polymer described above, and the effects that the present invention aims to achieve as described above can be achieved when the above characteristics are satisfied. However, in the case of other polymerization conditions, the physical properties of the modified rubbery polymer according to the present embodiment can be realized by controlling them in various ways.

[0173] The batch reactor may be, for example, a tank-type reactor equipped with a stirrer. In the batch reactor, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, a monomer is added continuously or intermittently during polymerization to obtain a polymer solution in the reactor, which is then discharged after the polymerization is completed.

[0174] In the method for producing a rubbery polymer of this embodiment, in order to obtain a copolymer having active ends in a high proportion, a continuous method is preferred, which allows the polymer to be continuously discharged and subjected to the next reaction in a short period of time.

[0175] In the polymerization step of the rubber-like polymer of this embodiment, the polymerization is preferably carried out in an inert solvent. The solvent is not particularly limited, but examples thereof include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; and hydrocarbons consisting of mixtures thereof.

[0176] Treating the impurities, that is, allenes and acetylenes, with an organometallic compound before subjecting the polymer to the polymerization reaction is preferred because it tends to give a polymer having a high concentration of active ends and a modified rubber-like polymer with a high modification rate.

[0177] In the polymerization process, a polar compound (polar substance) may be added. Aromatic vinyl compounds can be randomly copolymerized with conjugated diene compounds, and they tend to be useful as vinylating agents for controlling the microstructure of the conjugated diene moiety. They also tend to be effective in accelerating the polymerization reaction.

[0178] Examples of polar compounds that can be used include, but are not limited to, ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium amylate; and phosphine compounds such as triphenylphosphine.

[0179] These polar compounds may be used alone or in combination of two or more.

[0180] The amount of the polar compound used is not particularly limited and can be selected depending on the purpose, but is preferably 0.01 moles or more and 10 moles or less per mole of the polymerization initiator.

[0181] Such polar compounds (vinylating agents) can be used as modifiers for the microstructure of the conjugated diene moiety in the polymer in an appropriate amount depending on the desired amount of 1,2-vinyl bonds. Many polar compounds also have an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and tend to be used as modifiers for adjusting the distribution of the aromatic vinyl compound and the amount of styrene blocks.

[0182] 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 method may be used in which a copolymerization reaction is initiated with the entire amount of styrene and a portion of 1,3-butadiene, and the remaining 1,3-butadiene is intermittently added during the copolymerization reaction.

[0183] The polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds, and from the viewpoint of productivity, is more preferably 0°C or higher, and even more preferably 120°C or lower. By keeping the temperature in this range, it tends to be possible to ensure a sufficient amount of modifying agent reacting with the active terminals after the polymerization is completed. Even more preferably, it is 50°C or higher and 100°C or lower.

[0184] (Coupling Step) The active terminals of the copolymer obtained through the above-mentioned polymerization step and, if necessary, a branching step using a predetermined branching agent are subjected to a coupling reaction with the above-mentioned coupling agent or a modifying agent having a nitrogen atom-containing group.

[0185] (Deactivator Addition Step, Neutralizer Addition Step) In the method for producing a rubbery polymer of this embodiment, after the coupling step, a deactivator, neutralizer, etc. may be added to the polymer solution as needed.

[0186] The quenching agent is not limited to the following, but examples thereof include water; alcohols such as methanol, ethanol, and isopropanol; and the like.

[0187] Examples of the neutralizing agent include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, mainly 10 carbon atoms); aqueous solutions of inorganic acids; and carbon dioxide gas.

[0188] (Hydrogenation Step) In the method for producing a rubbery polymer of the present embodiment, the hydrogenation reaction may be carried out by carrying out the above-mentioned polymerization step, and, if necessary, a branching step, a coupling step, and, if necessary, a deactivator addition step.

[0189] (Rubber Stabilizer) In the method for producing a rubber polymer of this embodiment, it is preferable to add a rubber stabilizer from the viewpoint of preventing gel formation after polymerization and improving stability during processing.

[0190] The rubber stabilizer is not limited to the following and known stabilizers can be used, but preferred are 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-butylphenol)propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol.

[0191] (Solvent Removal Step) In the method for producing a rubbery polymer of this embodiment, a known method can be used to obtain the rubbery polymer from the polymer solution. The method is not particularly limited, but examples include a method in which the solvent is separated by steam stripping or the like, the polymer is filtered, and then the polymer is dehydrated and dried to obtain the polymer, a method in which the polymer is concentrated in a flashing tank and then devolatilized using a vent extruder or the like, and a method in which the polymer is directly devolatilized using a drum dryer or the like.

[0192] The rubber composition of the present embodiment may contain 100 parts by mass of the rubber-like polymer described above and 0.1 part by mass or more and 200 parts by mass or less of a filler.

[0193] The content of the filler in the rubber composition of this embodiment is more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, per 100 parts by mass of the rubber-like polymer, from the viewpoint of exhibiting a reinforcing effect. On the other hand, from the viewpoint of sufficiently dispersing the filler and ensuring that the rubber composition has practically sufficient processability and mechanical strength, the content of the filler in the rubber composition of this embodiment is preferably 150 parts by mass or less, per 100 parts by mass of the rubber-like polymer.

[0194] The filler is not particularly limited, but examples thereof include silica-based fillers, carbon black-based fillers, calcium carbonate, metal oxides, and metal hydrides. These may be used alone or in combination of two or more. Furthermore, fillers other than those mentioned above may also be contained.

[0195] As the filler, from the viewpoint of improving the breaking resistance and wet grip of the rubber composition of the present embodiment, a silica-based filler or a carbon black-based filler, or a combination of these, is preferred.

[0196] The silica-based filler is not particularly limited and known fillers can be used, but SiO ２ or Si ３ Solid particles containing Al as a constituent unit are preferred, and SiO ２ or Si ３ Solid particles containing Al as the main component of the structural units are more preferred. Here, the main component refers to a component contained in the silica-based filler in an amount of 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0197] Specific silica-based fillers include, but are not limited to, inorganic fibrous materials such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. Other examples include silica-based fillers with hydrophobic surfaces and mixtures of silica-based fillers with non-silica-based fillers. Among these, silica and glass fiber are preferred, and silica is more preferred, from the viewpoints of strength and abrasion resistance. Examples of silica include, but are not limited to, dry silica, wet silica, and synthetic silicate silica.

[0198] The carbon black filler is not limited to the following, but examples thereof include carbon blacks of various classes such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon blacks having a nitrogen adsorption specific surface area of ​​50 m ２ Carbon black having a carbon absorption of 80 mL / 100 g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or less is preferred.

[0199] The calcium carbonate is not particularly limited, but examples thereof include calcium carbonate having an average particle size of 0.04 μm to 8.0 μm and an oil absorption of 10 to 35 g per 100 g of calcium carbonate.

[0200] Metal oxides are compounds with the chemical formula M ｘ O ｙ(wherein M represents a metal atom, and x and y each independently represent an integer of 1 to 6) as the main component of the structural unit.

[0201] Examples of metal oxides include, but are not limited to, alumina, titanium oxide, magnesium oxide, and zinc oxide.

[0202] Examples of metal hydroxides include, but are not limited to, aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0203] The rubber composition of this embodiment may contain a silane coupling agent. The silane coupling agent has the function of strengthening the interaction between the rubber component (rubber-like polymer) and the filler (particularly an inorganic filler), and has groups that have affinity or bonding properties for both the rubber component and the silica-based filler (particularly an inorganic filler). Compounds having a sulfur-bonding moiety and an alkoxysilyl group or silanol group moiety in one molecule are preferred. Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0204] In the rubber composition of this embodiment, the content of the silane coupling agent is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and even more preferably 1.0 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the filler (particularly the inorganic filler). When the content of the silane coupling agent is within the above range, the effect of the addition of the silane coupling agent tends to be more pronounced.

[0205] (Rubber Softener) The rubber composition of the present embodiment may contain a rubber softener as needed. A rubber softener can be added as needed to further improve the productivity of the rubber polymer and the processability when a composition containing a filler or the like is prepared.

[0206] The rubber softener is not particularly limited, but examples thereof include extender oil, liquid rubber, and resin.

[0207] The method of adding a rubber softener to a rubber-like polymer or a rubber composition is not limited to the following, but a preferred method is to add the rubber softener to a copolymer solution, mix, and then remove the solvent from the resulting polymer solution containing the rubber softener.

[0208] Preferred extender oils include, for example, aromatic oils, naphthenic oils, paraffin oils, etc. Among these, from the viewpoint of environmental safety, oil bleed prevention, and wet grip properties, aromatic substitute oils having a polycyclic aromatic (PCA) content of 3% by mass or less according to the IP346 method are preferred. Examples of aromatic substitute oils include TDAE (Treated Distillate Aromatic Extracts), MES (Mild Extraction Solvate), etc. shown in Kautschuk Gummi Kunststoffe 52(12)799(1999), as well as RAE (Residual Aromatic Extracts).

[0209] Preferred liquid rubbers include, but are not limited to, liquid polybutadiene, liquid styrene-butadiene rubber, and the like.

[0210] The effect of adding liquid rubber is that it improves the processability of a rubber composition prepared by compounding a rubbery polymer with a filler or the like, and also shifts the glass transition temperature of the rubber composition to a lower temperature, which tends to improve the abrasion resistance, low hysteresis loss, and low-temperature properties of a vulcanized product.

[0211] Preferred resins include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including tung oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, monoolefin oligomers, diolefin oligomers, aromatic hydrocarbon resins, aromatic petroleum resins, hydrogenated aromatic hydrocarbon resins, cyclic aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated tung oil resins, hydrogenated oil resins, and esters of hydrogenated oil resins with monofunctional or polyfunctional alcohols. These resins may be used alone or in combination of two or more. When hydrogenating, all unsaturated groups may be hydrogenated, or some may remain.

[0212] The effects of adding a resin include improved processability when the polymer is compounded with a filler or the like to form a rubber composition, and also a tendency to improve the breaking strength when the rubber composition is vulcanized. Furthermore, the glass transition temperature of the rubber composition can be shifted to a higher temperature, which tends to improve wet skid resistance.

[0213] The amount of extender oil, liquid rubber, resin, or the like added as a rubber softener 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, and even more preferably 10 parts by mass or more and 37.5 parts by mass or less, per 100 parts by mass of the rubber-like polymer.

[0214] When the rubber softener is added within the above range, the processability of the rubber composition containing the rubbery polymer and a filler, etc. is improved, and the breaking strength and abrasion resistance of the vulcanized product tend to be improved.

[0215] Specific mixing methods for obtaining the rubber composition of the present embodiment include, but are not limited to, a melt-kneading method using a general mixer such as an open roll, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method in which the components are dissolved and mixed and then the solvent is removed by heating.

[0216] Among these, melt-kneading methods using a roll, a Banbury mixer, a kneader, or an extruder are preferred from the viewpoints of productivity and good kneading ability. Also applicable are a method of kneading the rubber component, other fillers, silane coupling agent, and additives all at once, and a method of mixing them in several batches.

[0217] (Vulcanized Composition) The rubber composition of the present embodiment may be a vulcanized composition that has been subjected to a vulcanization treatment with a vulcanizing agent.

[0218] Examples of vulcanizing agents include, but are not limited to, radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds.

[0219] The sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, polymeric polysulfide compounds, etc. In the rubber composition of this embodiment, the content of the vulcanizing agent is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the rubber-like polymer. 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, and more preferably 140°C or more and 180°C or less.

[0220] In vulcanization, a vulcanization accelerator may be used as needed.

[0221] As the vulcanization accelerator, a conventionally known material can be used, and examples thereof include, but are not limited to, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. Furthermore, examples of the vulcanization aid include, but are not limited to, zinc oxide, stearic acid, and triallyl isocyanurate. The content of the vulcanization accelerator is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the rubber-like polymer.

[0222] Examples of organic peroxides 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, and p-mene. Examples of the peroxide include tallow 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, and tert-butylperoxyisopropyl carbonate.

[0223] (Other Additives) The rubber composition of the present embodiment may contain various additives other than those described above, such as softeners and fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants, within the scope of the present embodiment.

[0224] As other softeners, known softeners can be used.

[0225] Examples of other fillers include, but are not limited to, magnesium carbonate, aluminum sulfate, and barium sulfate. Known materials can be used for the heat resistance stabilizer, antistatic agent, weather resistance stabilizer, antioxidant, colorant, and lubricant.

[0226] (Uses of Rubbery Polymer Cross-Linked Product (Cross-Linked Rubber Composition)) A cross-linked product (e.g., a cross-linked rubber composition) obtained using the rubbery polymer of this embodiment can be used as packing, gaskets, sealing materials, vibration-proof rubber, vibration-isolating rubber, conveyor belts, shoe outsoles and midsoles, automotive weatherstrips, glass runs, trunk lids, railway vehicle components, aircraft components, waterproof sheets, engine mounts, air springs, rubber gloves, medical and sanitary products, hoses for industrial and various uses, battery cases, adhesives, wire coatings, window frame rubber, rubber rolls, rubber rollers for office automation equipment and spinning, keypads, keyboard covers, underwater goggles, swimming caps, container bags, marine-related parts, indoor flooring materials, artificial muscle materials, materials for various industrial products, and the like. In these applications, various molded articles can be obtained by molding the cross-linked product (e.g., a cross-linked rubber composition) obtained using the rubbery polymer of this embodiment.

[0227] The present invention will be described in detail below with reference to examples. However, the examples of the present invention can be modified in various ways, and the scope of the present invention should not be construed as being limited to the examples described below. The examples of the present invention are provided to more completely explain the present invention to those skilled in the art.

[0228] [Methods for measuring physical properties] [Styrene content of rubbery polymer before hydrogenation, molar ratio of each structural unit represented by the structural formulas (1) to (4) of the rubbery polymer, hydrogenation rate, and styrene block amount] １ The content of aromatic vinyl monomer units (styrene content) was calculated from the integrated value of unsaturated bonds in the rubbery polymer before hydrogenation by H-NMR measurement. Next, a large amount of methanol was added to the reaction liquid after the hydrogenation reaction to precipitate and recover the rubbery polymer. Next, the rubbery polymer was extracted with acetone and dried under vacuum. This was１ The sample was used for H-NMR measurement to measure the hydrogenation rate of the rubbery polymer. １ The conditions for the H-NMR measurement are as follows:

[0229] (Measurement conditions) Measuring instrument: JNM-LA400 (manufactured by JEOL) Solvent: deuterated chloroform Measurement sample: sample taken before and after hydrogenation of rubber-like polymer Sample concentration: 50 mg / mL Observation frequency: 400 MHz Chemical shift reference: TMS (tetramethylsilane) Pulse delay: 2.904 seconds Number of scans: 64 times Pulse width: 45° Measurement temperature: 26°C

[0230] [Styrene Block Amount] A chain consisting of eight or more styrene structural units is defined as a styrene block, and the styrene block amount was determined as follows: １ The H-NMR spectrum was measured. From the spectrum, the integral ratio of each chemical shift range of the following (X) was calculated, and the amount of styrene blocks contained in the rubber-like polymer was determined. Aromatic vinyl compound chains of 8 or more: 6.00≦X<6.68

[0231] [Glass Transition Temperature] Using a rubbery polymer as a sample, the glass transition temperature was measured according to ISO 22768:2006. 10 mg of the sample was packed into a dedicated aluminum pan, and a Hitachi High-Tech Science DSC7020 differential scanning calorimeter was used as the measuring device. The sample was heated from 30°C to 160°C at 20°C / min and held for 2 minutes, then cooled from 160°C to -120°C at 10°C / min, and then heated from -120°C to 160°C at 10°C / min, while recording a DSC curve. The peak top (inflection point) of the DSC differential curve derived from the glass transition of the rubbery polymer when heated from -120°C to 160°C was taken as the glass transition temperature of the rubbery polymer.

[0232] The glass transition onset temperature of the rubbery polymer was taken as the temperature at the intersection of a straight line extending the low-temperature baseline toward the high-temperature side of the DSC curve obtained above with a tangent drawn at the point where the gradient of the stepwise change in the glass transition curve is maximum. The glass transition end temperature of the rubbery polymer was taken as the temperature at the intersection of a straight line extending the high-temperature baseline toward the low-temperature side of the DSC curve obtained above with a tangent drawn at the point where the gradient of the stepwise change in the glass transition curve is maximum. Using these methods, the difference between the glass transition onset temperature (onset, Tg-on) and the glass transition end temperature (offset, Tg-off) of the rubbery polymer ((Tg-off) - (Tg-on) °C, hereinafter also referred to as "difference in glass transition temperatures") was calculated.

[0233] [Calorimetric Calorific Value] Using a rubbery polymer as a sample, calorimetric value of crystallization was measured according to ISO 22768:2006. 10 mg of sample was placed in a dedicated aluminum pan, and a differential scanning calorimeter DSC7020 manufactured by Hitachi High-Tech Science was used as the measuring device. The sample was heated from 30°C to 160°C at 20°C / min and held for 2 minutes, then cooled from 160°C to -120°C at 10°C / min, and then heated from -120°C to 160°C at 10°C / min, while recording a DSC curve. The calorimetric value of crystallization of the rubbery polymer was determined from the peak area resulting from the crystallization of the rubbery polymer when the temperature was lowered from 160°C to -120°C.

[0234] [Nitrogen Atom Content of Rubber Polymer] Using a rubber polymer as a sample, the nitrogen atom content in the rubber polymer was measured using a trace nitrogen analyzer (Nitto Seiko Analytech TN-2100H).

[0235] [Weight-average molecular weight of rubbery polymer] The weight-average molecular weight of the rubbery polymer was measured by gel permeation chromatography (GPC). Specifically, the measurement was performed as follows.

[0236] A GPC measuring apparatus (manufactured by Tosoh Corporation under the trade name "HLC-8320GPC") in which three columns packed with polystyrene gel were connected was used, and a chromatogram was measured using an RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020"), and the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the rubbery polymer were determined based on a calibration curve obtained using standard polystyrene. The detailed measurement conditions were as follows. THF (tetrahydrofuran) containing 5 mmol / L triethylamine was used as the eluent. Three columns manufactured by Tosoh Corporation under the trade name "TSKgel SuperMultiporeHZ-H" were connected, and a guard column manufactured by Tosoh Corporation under the trade name "TSKguardcolumn SuperMP(HZ)-H" was connected to the preceding stage. 10 mg of the sample to be measured was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL / min.

[0237] (Preparation of hydrogenation catalyst) A reaction vessel purged with nitrogen was charged with 1 liter of dried and purified cyclohexane, and 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added. With sufficient stirring, an n-hexane solution containing 200 mmol of trimethylaluminum was added, and the mixture was reacted at room temperature for about 3 days to obtain a hydrogenation catalyst (TC).

[0238] Example 1 Of three continuous stirred tank reactors (CSTRs), n-hexane was continuously fed into the first reactor at a flow rate of 5.59 kg / hr, 1,3-butadiene at a flow rate of 0.84 kg / hr, styrene at a flow rate of 0.020 kg / hr, n-butyllithium at a flow rate of 0.55 g / hr, and ditetrahydrofurylpropane as a polar additive at a flow rate of 0.077 g / hr. 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, 0.096 kg / hr, 1,3-butadiene, 0.14 kg / hr, and ditetrahydrofurylpropane as a polar additive were continuously added to the second reactor at flow rates of 1.03 g / hr to participate in the reaction, and when the polymerization conversion rate reached 95% or more, the polymer was transferred from the second reactor to the third reactor through the transfer piping, and N,N-dimethyl-3-(trimethoxysilyl)propan-1-amine (hereinafter also referred to as "N1") as a modifier was added at a flow rate of 0.58 g / hr, and the reaction was carried out for 30 minutes. A portion of the resulting modified rubbery polymer solution was withdrawn and the solvent was removed in a dryer. The hydrogenation catalyst (TC) was then added to the rubbery polymer solution in an amount of 50 ppm (Ti basis) per 100 parts by mass of the rubbery polymer before hydrogenation, and the mixture was allowed to react at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C until the hydrogenation rate of the butadiene moiety reached 76 mol%. To the resulting rubbery polymer solution were added 0.3 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 0.1 g of 4,6-bis(octylthiomethyl)-o-cresol as antioxidants, per 100 g of polymer. The rubbery polymer solution was then added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain rubbery polymer A1. The resulting rubbery polymer A1 was analyzed using the methods described above, and the results are shown in Table 1.

[0239] [Example 2] A rubber-like polymer A2 was obtained in the same manner as in Example 1, except that the reaction was continued until the hydrogenation rate of the butadiene moiety reached 85 mol %. The obtained rubber-like polymer A2 was analyzed by the above-mentioned methods, and the results are shown in Table 1.

[0240] [Example 3] A rubber-like polymer A3 was obtained in the same manner as in Example 1, except that the reaction was continued until the hydrogenation rate of the butadiene moiety reached 95 mol %. The obtained rubber-like polymer A3 was analyzed by the above-mentioned methods, and the results are shown in Table 1.

[0241] [Example 4] A rubber-like polymer A4 was obtained in the same manner as in Example 1, except that the reaction was continued until the hydrogenation rate of the butadiene moiety reached 55 mol %. The obtained rubber-like polymer A4 was analyzed by the above-mentioned methods, and the results are shown in Table 1.

[0242] [Example 5] A rubber-like polymer A5 was obtained in the same manner as in Example 1, except that the reaction was continued until the hydrogenation rate of the butadiene moiety reached 35 mol %. The obtained rubber-like polymer A5 was analyzed by the above-mentioned methods, and the results are shown in Table 1.

[0243] [Example 6] A rubber-like polymer A6 was obtained in the same manner as in Example 1, except that the reaction was continued until the hydrogenation rate of the butadiene moiety reached 20 mol %. The obtained rubber-like polymer A6 was analyzed by the above-mentioned methods, and the results are shown in Table 1.

[0244] Example 7 A rubbery polymer A7 was obtained in the same manner as in Example 1, except that the modifier was changed to 1,3-dimethyl-2-imidazolidinone (hereinafter also referred to as "N2") and the flow rate was changed to 0.32 g / hr. The obtained rubbery polymer A7 was analyzed by the above-mentioned method, and the results are shown in Table 1.

[0245] Example 8 Except for not adding a modifier, a rubbery polymer A8 was obtained in the same manner as in Example 1. The obtained rubbery polymer A8 was analyzed by the above-mentioned method, and the results are shown in Table 1.

[0246] Comparative Example 1 Except for not carrying out hydrogenation, a rubbery polymer A9 was obtained in the same manner as in Example 1. The obtained rubbery polymer A9 was analyzed by the above-mentioned method, and the results are shown in Table 1.

[0247] Example 9 A rubbery polymer A10 was obtained in the same manner as in Example 1, except that the flow rates of 1,3-butadiene were changed to 0.56 kg / hr in the first reactor and 0.096 kg / hr in the second reactor, the flow rate of styrene was changed to 0.35 kg / hr, and the flow rates of ditetrahydrofurylpropane were changed to 0.10 g / hr in the first reactor and 1.32 g / hr in the second reactor, and the reaction was carried out until the hydrogenation rate of the butadiene moiety reached 82 mol%. The obtained rubbery polymer A10 was analyzed by the above-mentioned methods, and the results are shown in Table 2.

[0248] Comparative Example 2 A rubber polymer A11 was obtained in the same manner as in Example 9, except that hydrogenation was not carried out. The obtained rubber polymer A11 was analyzed by the above-mentioned method, and the results are shown in Table 2.

[0249] Example 10 A rubbery polymer A12 was obtained in the same manner as in Example 1, except that the flow rates of 1,3-butadiene were changed to 0.63 kg / hr in the first reactor and 0.11 kg / hr in the second reactor, the flow rate of styrene was changed to 0.26 kg / hr, and the flow rates of ditetrahydrofurylpropane were changed to 0.17 g / hr in the first reactor and 2.2 g / hr in the second reactor, and the reaction was carried out until the hydrogenation rate of the butadiene moiety reached 80 mol%. The obtained rubbery polymer A12 was analyzed by the above-mentioned methods, and the results are shown in Table 3.

[0250] Comparative Example 3 A rubber polymer A13 was obtained in the same manner as in Example 10, except that hydrogenation was not carried out. The obtained rubber polymer A13 was analyzed by the above-mentioned methods, and the results are shown in Table 3.

[0251] Example 11 A rubbery polymer A14 was obtained in the same manner as in Example 1, except that the flow rates of 1,3-butadiene were changed to 0.70 kg / hr in the first reactor and 0.12 kg / hr in the second reactor, the flow rate of styrene was changed to 0.19 kg / hr, and the flow rates of ditetrahydrofurylpropane were changed to 0.045 g / hr in the first reactor and 0.6 g / hr in the second reactor, and the reaction was carried out until the hydrogenation rate of the butadiene moiety reached 55 mol%. The obtained rubbery polymer A14 was analyzed by the above-mentioned methods, and the results are shown in Table 4.

[0252] [Example 12] A rubber-like polymer A15 was obtained in the same manner as in Example 11, except that the reaction was continued until the hydrogenation rate of the butadiene moiety reached 78 mol%. The obtained rubber-like polymer A15 was analyzed by the above-mentioned methods, and the results are shown in Table 4.

[0253] [Example 13] A rubber-like polymer A16 was obtained in the same manner as in Example 11, except that the reaction was continued until the hydrogenation rate of the butadiene moiety reached 95 mol %. The obtained rubber-like polymer A16 was analyzed by the above-mentioned methods, and the results are shown in Table 4.

[0254] [Example 14] A rubber-like polymer A17 was obtained in the same manner as in Example 12, except that styrene was introduced into the second reactor instead of the first reactor. The obtained rubber-like polymer A17 was analyzed by the above-mentioned methods, and the results are shown in Table 4.

[0255] Comparative Example 4 Except for not carrying out hydrogenation, a rubbery polymer A18 was obtained in the same manner as in Example 11. The obtained rubbery polymer A18 was analyzed by the above-mentioned method, and the results are shown in Table 4.

[0256]

[0257]

[0258]

[0259]

[0260] Comparative Example 5 (Polymerization / Modification Step) A 40 L internal volume, temperature-controllable autoclave equipped with a stirrer and jacket was used as a reactor. 2,850 g of 1,3-butadiene, 150 g of styrene, 21,000 g of cyclohexane, and 29.1 mmol of tetrahydrofuran (THF) and 2.2 mmol of 2,2-bis(2-oxolanyl)propane (BOP) as polar substances were placed in 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 polymerization reaction began, the temperature inside the reactor rose due to heat generated by the polymerization, and the final temperature inside the reactor was 78°C. 15.2 mmol of tetraglycidyl-1,3-bisaminomethylcyclohexane (hereinafter also referred to as "N3") was added as a modifier to this polymer solution, and the reaction was carried out for 15 minutes. Thereafter, 15.2 mmol of methanol was added as a reaction terminator. (Hydrogenation Step) Furthermore, the hydrogenation catalyst (TC) was added to the polymer solution in an amount of 50 ppm (Ti standard) 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 moiety reached 82%. To the resulting polymer solution, 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, and the conjugated diene polymer solution was then added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain rubbery polymer B1. The resulting rubbery polymer B1 was analyzed by the above-mentioned methods, and the analytical results are shown in Table 5.

[0261] Example 15 A rubbery polymer B2 was obtained in the same manner as in Comparative Example 5, except for the following change in the hydrogenation step. (Hydrogenation Step) A reactor was used, equipped with a rotary agitator rotating at 114 rpm, with an internal volume of 40 L, an L / D ratio (L: reactor height, D: reactor diameter) of 2.2, and equipped with three nozzles at the top and three nozzles at the bottom (top: nozzle A, nozzle B, and nozzle C, bottom: nozzle D, nozzle E, and nozzle F), and one nozzle (nozzle G) in the center of the reactor. The temperature of the reactor was adjusted to 90°C, and then the conjugated diene polymer solution obtained above was fed from nozzle A at the top of the reactor at a rate of 1.7 kg / hr. The hydrogenation catalyst (TC) was added to the polymer solution so that the concentration was 50 ppm (based on titanium) relative to the amount of charged monomers, and the solution was withdrawn from nozzle D at the bottom of the reactor while adjusting the liquid level in the reactor to 60%. At this time, the average residence time τ of the polymer was 70 minutes, and H / D (H: height of the liquid surface, 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 so as to reach 0.6 MPa, and the supply was immediately stopped. The polymer flowing out from outlet 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 equation (a), whereby the number of complete mixing vessels, N, was approximated to be 1.1. Under the above reactor conditions, hydrogen was continuously supplied to the reaction mixture so that the pressure became 0.6 MPa, and the reaction was continued until the hydrogenation rate of the butadiene moiety reached 82%. The rubber-like polymer B2 thus obtained was analyzed by the above-mentioned methods, and the results are shown in Table 5.

[0262] Example 16 Polymerization / Modification Step Of three continuous stirred tank reactors (CSTRs), n-hexane was continuously fed into the first reactor at a flow rate of 5.59 kg / hr, 1,3-butadiene at a flow rate of 0.81 kg / hr, styrene at a flow rate of 0.050 kg / hr, n-butyllithium at a flow rate of 0.55 g / hr, and ditetrahydrofurylpropane as a polar additive at a flow rate of 0.077 g / hr. During this process, 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, 0.093 kg / hr, 1,3-butadiene, 0.14 kg / hr, and ditetrahydrofurylpropane as a polar additive were continuously added to the second reactor at flow rates of 1.03 g / hr to participate in the reaction, and when the polymerization conversion rate reached 95% or more, the polymer was transferred from the second reactor to the third reactor through the transfer piping, and tetraglycidyl-1,3-bisaminomethylcyclohexane (hereinafter also referred to as "N3") as a modifier was added at a flow rate of 1.02 g / hr, and the reaction was carried out for 30 minutes. A portion of the resulting modified rubbery polymer solution was withdrawn and the solvent was removed in a dryer. (Hydrogenation Step) The hydrogenation catalyst (TC) was then added to the rubbery polymer solution in an amount of 50 ppm (Ti basis) per 100 parts by mass of the rubbery polymer before hydrogenation, and the reaction was continued at a hydrogen pressure of 0.8 MPa and an average temperature of 85°C until the hydrogenation rate of the butadiene moiety reached 76 mol%. To the resulting rubbery polymer solution, 0.3 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate and 0.1 g of 4,6-bis(octylthiomethyl)-o-cresol were added as antioxidants per 100 g of polymer. The rubbery polymer solution was then added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain rubbery polymer B3. The resulting rubbery polymer B3 was analyzed using the methods described above, and the analytical results are shown in Table 5.

[0263] [Example 17] Rubber 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. The obtained rubber polymer B4 was analyzed by the above-mentioned methods, and the results are shown in Table 5.

[0264]

[0265] [Evaluation of Compound Properties] Using the rubbery polymers shown in Tables 1 to 5, rubber compositions containing each rubbery polymer were obtained according to the formulation shown below. Rubbery polymer: 100 parts by mass (oil excluded) 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" manufactured by Evonik Degussa, bis(triethoxysilylpropyl)tetrasulfide): 6.8 parts by mass S-RAE oil (trade name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation): 40 parts by mass Zinc oxide: 2.4 parts by mass Stearic acid: 1.25 parts by mass Antioxidant (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 3.5 parts by mass Sulfur: 1.0 part by mass Vulcanization accelerator 1 Tetrabenzyl thiuram disulfide: 0.5 parts by mass Vulcanization accelerator 2 N-(tert-butyl)-2-benzothiazole sulfenamide: 2.5 parts by mass Total: 246.95 parts by mass

[0266] The above materials were kneaded by the following method to obtain rubber compositions. Using an internal kneader (0.3 L capacity) equipped with a temperature control device, the rubber-like polymers (samples 1 to 25), fillers (silica, carbon black), silane coupling agent, process oil, zinc oxide, and stearic acid were kneaded in the first stage at a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm. The temperature of the internal mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 145 to 150°C.

[0267] Next, in the second stage of mixing, the compound obtained above was cooled to room temperature, and then an antioxidant was added. The compound was then mixed again to improve the dispersion of the silica. Again, the temperature of the mixer was controlled to 120°C to discharge the compound. After cooling, in the third stage of mixing, sulfur and vulcanization accelerators 1 and 2 were added and mixed using an open roll set at 70°C. The resulting mixture was then molded and vulcanized in a vulcanization press at 160°C for 20 minutes. The rubber compositions before and after vulcanization were evaluated. Specifically, the evaluations were carried out using the following methods. For the results of Examples 1 to 8, Comparative Example 1 was used; for Example 9, Comparative Example 2; for Example 10, Comparative Example 3; for Examples 11 to 14, Comparative Example 4; and for Examples 15 to 17, Comparative Example 5. The results for the rubber compositions using the rubbery polymers obtained for each comparison were indexed, with the results calculated as 100.

[0268] [Evaluation 1 and Evaluation 2: Viscoelasticity Parameter] The viscoelasticity parameter (tan δ) was measured in a torsion mode using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific.

[0269] (Evaluation 1) Tan δ measured at 60° C., a frequency of 10 Hz, and a strain of 3% was used as an index of fuel economy. A larger index indicates better fuel economy.

[0270] (Evaluation 2) Tan δ measured at 0° C., a frequency of 10 Hz, and a strain of 1% was used as an index of wet grip performance. A larger index indicates better wet grip performance.

[0271] (Evaluation 3) Using an Acron abrasion tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the amount of abrasion was measured at a load of 44.4 N and 1000 revolutions in accordance with JIS K6264-2. A higher index indicates better abrasion resistance.

[0272] (Evaluation 4) In accordance with the tensile test method of JIS K6251, the tensile strength and tensile elongation were measured at 0°C using a tensile tester with a thermostatic chamber, and the product of these values ​​was expressed as an index representing the material strength in a low-temperature environment. A larger index indicates better material strength in a low-temperature environment.

[0273] As can be seen from Tables 1 to 5, it was confirmed that the rubbery polymers obtained in Examples 1 to 17, compared to the rubbery polymers obtained in Comparative Examples 1 to 5, had both wet grip properties and abrasion resistance, and further had high material strength in a low-temperature environment corresponding to wet grip.

[0274] This application is based on a Japanese patent application (Patent Application No. 2023-195105) filed on November 16, 2023, the contents of which are incorporated herein by reference.

[0275] The rubbery polymer and rubber composition of the present invention, as well as crosslinked products (e.g., crosslinked rubber compositions) obtained using the rubbery polymer of the present invention, have industrial applicability, for example, as packings, gaskets, sealing materials, vibration-proof rubber, vibration-isolating rubber, vibration-damping materials, conveyor belts, shoe outsoles and shoe midsoles, automobile weather strips, glass runs, trunk lids, railway vehicle components, aircraft components, waterproof sheets, engine mounts, air springs, rubber gloves, medical and sanitary products, hoses for industrial and various uses, battery cases, adhesives, wire coatings, window frame rubber, rubber rollers for office automation equipment and spinning, etc., keypads, keyboard covers, underwater goggles, swimming caps, container bags, marine-related parts, indoor flooring materials, artificial muscle materials, and materials for various industrial products.

Claims

1. A rubber-like polymer comprising two or more structural units selected from the group consisting of structural units represented by the following formulas (1) to (4), including at least a structural unit represented by formula (2) among the structural units; having a weight average molecular weight of 100,000 or more as measured by gel permeation chromatography (GPC); and having a difference between the glass transition onset temperature (onset, Tg-on) and the glass transition end temperature (offset, Tg-off) of 10°C or more and 40°C or less as measured by differential scanning calorimetry (DSC).

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

3. The rubber-like polymer according to claim 1 or 2, wherein the difference between the glass transition onset temperature (Tg-on) and the glass transition end temperature (Tg-off) is 10°C or more and 30°C or less.

4. A rubber-like polymer according to claim 1 or 2, in which the content S of aromatic vinyl monomer units is 1% by mass or more and 8% by mass or less.

5. A rubber-like polymer according to claim 1 or 2, wherein, when the total content of the structural units represented by the formulas (1) to (4) is taken as 100 mol%, the total 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 50 mol% or more and 60 mol% or less.

6. The rubbery polymer according to claim 1 or 2, which has a heat of crystallization derived from a crystallization peak measured by differential scanning calorimetry (DSC) of more than 50 J / g.

7. The rubber-like polymer according to claim 1 or 2, having a nitrogen atom content of 30 ppm or more based on the total mass of the rubber-like polymer.

8. The rubbery polymer according to claim 1 or 2, wherein the rubbery polymer is a modified rubbery polymer modified with a modifying agent, and the modifying agent 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 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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