Hydrogenated conjugated diene polymer, and method for manufacturing hydrogenated conjugated diene polymer

Abstract

A hydrogenated conjugated diene polymer that satisfies conditions (i)-(iii).　Condition (i): The polymer is a random polymer that contains a conjugated diene monomer unit and may contain an aromatic vinyl monomer unit. When the aromatic vinyl monomer unit is contained, the content of the aromatic vinyl monomer block is less than 10 mass% of the hydrogenated conjugated diene polymer.　Condition (ii): The weight-average molecular weight is 10×104 to 200×104.　Condition (iii): The half-value width temperature of the elution amount peak measured by temperature gradient interaction chromatography is in the range of 20-80°C.

Description

Hydrogenated conjugated diene polymer and method for producing hydrogenated conjugated diene polymer

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

[0002] Conventionally, rubber products such as tires have been required to have improved durability such as ozone resistance and breaking strength, as well as excellent low hysteresis loss. For example, Patent Documents 1 and 2 propose technologies relating to rubber compositions containing hydrogenated conjugated diene polymers and having improved ozone resistance.

[0003] International Publication No. 2017 / 014282 Patent No. 6845679

[0004] However, as described in Patent Documents 1 and 2, when the hydrogenation process of a conjugated diene polymer is carried out batchwise, increasing the hydrogenation rate of the conjugated diene polymer to improve the ozone resistance of the rubber composition results in a significant increase in the viscosity of the resulting hydrogenated conjugated diene polymer due to entanglement of polymer chains, significantly deteriorating the processability of the hydrogenated conjugated diene polymer and the rubber composition. Reducing the molecular weight of the conjugated diene polymer to improve the processability results in a deterioration in cold flow resistance and a decrease in break physical properties. Lowering the hydrogenation rate improves processability, but degrades the ozone resistance, break physical properties, and cold flow resistance. On the other hand, although the cold flow resistance (fluidity) and break physical properties of the hydrogenated conjugated diene polymer and the rubber composition can be improved by introducing a small amount of an aromatic vinyl monomer block into the conjugated diene polymer, this also results in a deterioration in low hysteresis loss.

[0005] That is, the above-mentioned conventionally proposed hydrogenated conjugated diene polymers and rubber compositions have the problem that it is difficult to achieve excellent ozone resistance, break properties, and low hysteresis loss while ensuring good processability and cold flow resistance.

[0006] In view of the above-mentioned problems of the conventional art, the present invention aims to provide a hydrogenated conjugated diene polymer that can achieve excellent processability, ozone resistance, physical properties at break, and low hysteresis loss when made into a rubber composition while ensuring good processability and cold flow resistance.

[0007] The present inventors have conducted extensive research to solve the above-mentioned problems of the conventional art, and as a result have found that a hydrogenated conjugated diene polymer having a specific aromatic vinyl monomer block amount, weight-average molecular weight, and half-width temperature of an elution amount peak measured by temperature gradient interaction chromatography (hereinafter referred to as "TGIC") can solve the above-mentioned problems, thereby completing the present invention.

[0008] [1] A hydrogenated conjugated diene polymer satisfying the following conditions (i) to (iii): <Condition (i)> The polymer contains conjugated diene monomer units and may contain aromatic vinyl monomer units, and when the aromatic vinyl monomer units are contained, the polymer is a random polymer, and the content of the aromatic vinyl monomer blocks is less than 10% by mass of the hydrogenated conjugated diene polymer. <Condition (ii)> The weight average molecular weight is 10 x 10 ４ Above 200 x 10 ４ or less. <Condition (iii)> The half-width temperature of the elution amount peak measured by temperature gradient interaction chromatography is in the range of 20 to 80°C. [2] The hydrogenated conjugated diene polymer according to [1] above, having a hydrogenation rate of 97 mol% or less. [3] The hydrogenated conjugated diene polymer according to [1] or [2] above, having a hydrogenation rate of 50 mol% or more. [4] The hydrogenated conjugated diene polymer according to any one of [1] to [3] above, having an ethylene structure, and the ethylene structure accounts for 1 mass% or more. [5] The hydrogenated conjugated diene polymer according to any one of [1] to [4] above, containing an aromatic vinyl monomer unit. [6] A method for producing the hydrogenated conjugated diene polymer according to any one of [1] to [5] above, wherein the weight-average molecular weight is 10 x 10 ４ Above 200 x 10 ４The method for producing a hydrogenated conjugated diene polymer comprises: a polymerization step of obtaining a conjugated diene polymer having an aromatic vinyl monomer block content of less than 10% by mass; a hydrogenation step of obtaining a plurality of types of hydrogenated conjugated diene polymers having different hydrogenation rates; and a mixing step of mixing the plurality of types of hydrogenated conjugated diene polymers to make the hydrogenation rate distribution HWD, represented by the following formula (1), 1.005 or more.

[0009]

[0010] In formula (1), n ​​represents the total number of components of hydrogenated conjugated diene polymers having different hydrogenation rates, and w ｉ is a specific hydrogenation rate H ｉ represents the mass fraction of the hydrogenated conjugated diene polymer having the formula (I) in the total hydrogenated conjugated diene polymer.

[0011] [7] The method for producing the hydrogenated conjugated diene polymer according to any one of [1] to [5], wherein the weight average molecular weight is 10 × 10 ４ Above 200 x 10 ４ A method for producing a hydrogenated conjugated diene polymer, comprising: a polymerization step of obtaining a conjugated diene polymer having an aromatic vinyl monomer block content of less than 10% by mass; and a hydrogenation step of adding hydrogen to the conjugated diene polymer, wherein the hydrogenation step is a continuous process, and the number N of perfect mixing vessel rows is 1.0 to 2.5 when the residence time distribution in the reactor is fitted to a perfect mixing vessel row model by an impulse response method. [8] The method for producing a hydrogenated conjugated diene polymer according to [7] above, wherein hydrogen and the conjugated diene polymer are supplied to a reactor in the hydrogenation step from opposite directions, or hydrogen and / or the conjugated diene polymer are each supplied from a plurality of locations. [9] The method for producing a hydrogenated conjugated diene polymer according to [7], wherein the continuous process uses a stirred tank reactor, supplies the conjugated diene polymer and a hydrogenation catalyst from an upper part of the stirred tank reactor, and stirs the mixture while supplying hydrogen from a bottom part of the stirred tank reactor, and extrudes the hydrogenated conjugated diene polymer from the bottom part of the stirred tank reactor.

[0012] According to the present invention, it is possible to provide a hydrogenated conjugated diene polymer that has good processability and cold flow resistance, and that, when made into a rubber composition, has excellent processability, ozone resistance, physical properties at break, and low hysteresis loss.

[0013] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the following present embodiment is an example for explaining the present invention, and the present invention is not limited to the following embodiment. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0014] [Hydrogenated Conjugated Diene Polymer] The hydrogenated conjugated diene polymer of this embodiment satisfies the following conditions (i) to (iii): <Condition (i)> The polymer contains conjugated diene monomer units and may contain aromatic vinyl monomer units, and when the aromatic vinyl monomer units are contained, the polymer is a random polymer, and the content of the aromatic vinyl monomer blocks is less than 10% by mass of the hydrogenated conjugated diene polymer. <Condition (ii)> The weight average molecular weight is 10 x 10 ４ Above 200 x 10 ４ <Condition (iii)> The half-width temperature of the elution amount peak measured by temperature gradient interaction chromatography (hereinafter, sometimes referred to as TGIC) is in the range of 20 to 80°C.

[0015] According to the above configuration, the processability and cold flow resistance are good, and as will be described later, when the hydrogenated conjugated diene-based polymer of the present embodiment is appropriately combined with other polymers, filler components, plasticizer components, crosslinking agent components, etc. to form a rubber composition, the processability, ozone resistance, break physical properties, and low hysteresis loss are excellent.

[0016] The hydrogenated conjugated diene polymer of this embodiment has a structure in which hydrogen is added to a structural unit based on a conjugated diene compound (hereinafter also referred to as a "conjugated diene monomer unit") and a portion polymerized using a conjugated diene compound as a monomer. The hydrogenated conjugated diene polymer of this embodiment preferably contains a structural unit based on an aromatic vinyl compound (aromatic vinyl monomer unit). The hydrogenated conjugated diene polymer of this embodiment may have a structural unit based on ethylene (hereinafter sometimes referred to as an "ethylene structure"). The ethylene structure is formed by converting a portion of the double bond moiety into an ethylene structure by hydrogenating a conjugated diene monomer unit, or by copolymerizing a conjugated diene compound with ethylene.

[0017] From the viewpoint of production costs, the ethylene structure of the hydrogenated conjugated diene polymer of this embodiment is preferably obtained by subjecting a conjugated diene polymer to a hydrogenation reaction. The content of ethylene structures can be increased by controlling the hydrogenation rate to a high level. In the hydrogenated conjugated diene polymer of this embodiment, the ethylene structure is defined as a structure in which hydrogen is added to a bond that forms a polymer chain at both ends of the main chain of a conjugated diene monomer unit (for example, a 1,4-bond in a polymer in which 1,3-butadiene is used as a monomer), and a structure in which hydrogen is added to other bonds (for example, a 1,2-vinyl bond in a polymer in which 1,3-butadiene is used as a monomer) is not included in the ethylene structure.

[0018] Conjugated diene compounds used to form the conjugated diene monomer units that constitute the hydrogenated conjugated diene polymer of this embodiment include, but are not limited to, 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, and the like. These may be used alone or in combination of two or more. Of these, from the viewpoint of practical aspects such as easy availability of monomers, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is more preferred.

[0019] (Condition (i) Content of Aromatic Vinyl Monomer Units) The hydrogenated conjugated diene polymer of the present embodiment may contain aromatic vinyl monomer units. When the hydrogenated conjugated diene polymer contains the aromatic vinyl monomer units, the polymer is a random polymer. The content of the aromatic vinyl monomer units in the hydrogenated conjugated diene polymer is preferably 2% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on the total amount of the hydrogenated conjugated diene polymer, from the viewpoint of the breaking strength of the rubber composition of the present embodiment, which will be described later. Furthermore, the content of the aromatic vinyl monomer units is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, based on the total amount of the hydrogenated conjugated diene polymer, from the viewpoint of low hysteresis loss of the rubber composition of the present embodiment. The content of the aromatic vinyl monomer units can be measured by the method described in the examples below. The content of the aromatic vinyl monomer units can be controlled within the above-mentioned range by adjusting the timing and amount of addition of the aromatic vinyl compound in the polymerization step of the conjugated diene polymer, and the polymerization time.

[0020] Examples of aromatic vinyl compounds that form aromatic vinyl monomer units include, but are not limited to, styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, and 2,4,6-trimethylstyrene. These compounds may be used alone or in combination of two or more. Among these compounds, styrene is particularly preferred from the viewpoint of practical aspects such as easy availability of the monomer.

[0021] (Condition (i) Content of aromatic vinyl monomer block) From the viewpoint of low hysteresis loss of the rubber composition of the present embodiment, the hydrogenated conjugated diene polymer of the present embodiment has a content of aromatic vinyl monomer block, i.e., the content of long chain ratio of structural units based on aromatic vinyl compounds, of less than 10 mass%, preferably 7 mass% or less, and more preferably 5 mass% or less, relative to the total mass of the hydrogenated conjugated diene polymer of the present embodiment. The low hysteresis loss of the rubber composition contributes to fuel efficiency of tires when used as tire rubber, and also contributes to the property of small stress change during repeated deformation when used in industrial products such as cushion rubber. The content of the aromatic vinyl monomer block in the hydrogenated conjugated diene polymer of the present embodiment can be controlled within the above numerical range, for example, by adjusting the amount and timing of addition of the aromatic vinyl compound, the amount of randomizer added, etc. in the polymerization step.

[0022] (Condition (i): Random Polymer) When the hydrogenated conjugated diene polymer of this embodiment contains an aromatic vinyl monomer unit, it is a random polymer from the viewpoint of low hysteresis loss of the rubber composition of this embodiment. In this specification, the term "random polymer" means that the long chain ratio of aromatic vinyl monomer units is less than 10 mass% with respect to the total mass of the hydrogenated conjugated diene polymer. Here, the long chain ratio is the ratio of chains (long chains) in which 8 or more structural units are consecutive with respect to all structural units. In this specification, when the "random polymer" is a polymer using two or more types of monomer units, the two or more types of monomer units may be distributed uniformly in the polymer, or may be distributed in a tapered, stepped, convex, or concave shape.

[0023] Here, the long chain ratio of aromatic vinyl monomer units was measured using the hydrogenated conjugated diene polymer of this embodiment as a measurement sample and deuterated chloroform as a solvent. １It can be obtained by calculating the integral ratio of each chemical shift range (X) below in the H-NMR spectrum. Using this measured value, the content of aromatic vinyl monomer blocks contained in the hydrogenated conjugated diene polymer was determined. For example, when the aromatic vinyl monomer is styrene, a chain of eight or more styrene structural units is considered to be a long styrene chain, and the amount of styrene blocks can be determined. Eight or more chains of aromatic vinyl monomer units: 6.00≦X<6.68

[0024] As described above, from the viewpoint of low hysteresis loss of the rubber composition, the hydrogenated conjugated diene polymer of this embodiment is a random polymer when it contains the aromatic vinyl monomer unit. Furthermore, the hydrogenated conjugated diene polymer of this embodiment may be modified or unmodified, but from the viewpoint of reinforcement and abrasion resistance due to the filler component of the rubber composition, it is preferably a modified random polymer. The modification method will be described later, and an example of a modified hydrogenated conjugated diene polymer is one in which a functional group is introduced into the polymerization terminal of the polymer using a modifier.

[0025] (Amount of Ethylene Structures and Hydrogenation Ratio) The hydrogenated conjugated diene polymer of this embodiment preferably has 1% by mass or more of ethylene structures, more preferably 2% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of ozone resistance and tensile strength of a rubber composition containing the hydrogenated conjugated diene polymer of this embodiment. The upper limit of the ethylene structures is preferably 95% by mass or less, more preferably 90% by mass or less, from the viewpoint of processability, although this depends on the content of aromatic vinyl monomer units before hydrogenation and the amount of 1,2-vinyl bonds.

[0026] The amount of ethylene structures in the hydrogenated conjugated diene polymer of the present embodiment can be controlled by adjusting the ratio of styrene to 1,3-butadiene, the ratio of 1,4-bonds to 1,2-vinyl bonds in the butadiene moiety, and the hydrogenation rate, for example, in the case of a polymer formed from styrene and 1,3-butadiene as monomers. Methods for increasing the amount of ethylene structures include a method of decreasing the styrene ratio and increasing the butadiene ratio, a method of increasing the 1,4-bond ratio in the butadiene moiety, and a method of increasing the hydrogenation rate. Conversely, the amount of ethylene structures can be reduced by increasing the styrene ratio and decreasing the butadiene ratio, decreasing the 1,4-bond ratio in the butadiene moiety, or decreasing the hydrogenation rate. For example, in the case of a polymer formed from 1,3-butadiene as a monomer, 1,4-bonds and 1,2-vinyl bonds are produced by polymerization, and when a polymer containing both bonds is hydrogenated, the hydrogenation reaction of the 1,2-vinyl bonds proceeds more quickly and tends to be preferentially hydrogenated. Therefore, in order to "contain 1% by mass or more of ethylene structures," it is preferable to form 1,4-bonds by polymerization in an amount exceeding 1% by mass in the conjugated diene polymer before hydrogenation, and then carry out the hydrogenation reaction to an extent that most of the 1,2-vinyl bonds are consumed and 1% by mass or more of the 1,4-bonds are hydrogenated, so that 1% by mass or more of ethylene structures are formed in the hydrogenated conjugated diene copolymer. Specifically, the hydrogenation rate is preferably 1% or more, and more preferably 2% or more, higher than the proportion of 1,2-vinyl bonds in the proportion of conjugated diene monomer units. However, when the hydrogenation rate has a distribution as described below, even if the hydrogenation rate is lower than the amount of 1,2-vinyl bonds, 1% by mass or more of the 1,4-bonds may also be hydrogenated in the conjugated diene polymer before hydrogenation. The hydrogenation rate (proportion of hydrogenated units relative to the conjugated diene units) is preferably such that 1,4-bonds are hydrogenated so that the hydrogenated conjugated diene polymer contains 1% by mass or more of ethylene structures. Although it depends on the amount of 1,2-vinyl bonds before hydrogenation, the hydrogenation rate is preferably 50 mol % or more, more preferably 60 mol % or more, and even more preferably 70 mol % or more.Furthermore, from the viewpoint of fully exhibiting the effect of the hydrogenation rate distribution described below, the hydrogenated conjugated diene polymer of this embodiment preferably has a hydrogenation rate of 97 mol% or less, more preferably 93 mol% or less, even more preferably 90 mol% or less, still more preferably 88 mol% or less, and even more preferably 85 mol% or less. １ It can be calculated from the spectral reduction rate of unsaturated bonds in the spectrum obtained by measuring H-NMR, and when the hydrogen conversion rate has a distribution as described below, it corresponds to the average hydrogenation rate.

[0027] (Condition (ii) Weight-average molecular weight) The hydrogenated conjugated diene polymer of the present embodiment has a weight-average molecular weight (Mw) of 10 × 10 ４ or more, preferably 15×10 ４ More preferably, 20×10 ４ In addition, the weight average molecular weight of the hydrogenated conjugated diene polymer is set to 200×10 from the viewpoint of processability of the hydrogenated conjugated diene polymer and the rubber composition of the present embodiment. ４ or less, preferably 100×10 ４ or less, and more preferably 70×10 ４ The following is the result.

[0028] (Molecular Weight Distribution) From the viewpoint of processability of the hydrogenated conjugated diene polymer and the rubber composition, the hydrogenated conjugated diene polymer of this embodiment has a molecular weight distribution (Mw / Mn) of preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more. From the viewpoint of low hysteresis loss of the rubber composition, the molecular weight distribution of the hydrogenated conjugated diene polymer of this embodiment is preferably 4.0 or less, more preferably 3.5 or less, and even more preferably 3.0 or less. The weight average molecular weight (Mw) and number average molecular weight (Mn) can be measured by the method described in the Examples below.

[0029] (Condition (iii) Half-width temperature of elution amount peak measured by temperature gradient interaction chromatography (TGIC)) The hydrogenated conjugated diene polymer of this embodiment has a half-width temperature of elution amount peak measured by temperature gradient interaction chromatography (TGIG) in the range of 20 to 80°C. The "half-width temperature of elution amount peak" refers to the temperature difference (the higher temperature minus the lower temperature) at the point where a line drawn parallel to the baseline at half the height of the elution amount peak measured by temperature gradient interaction chromatography (TGIG) described below intersects with an elution distribution graph of the hydrogenated conjugated diene polymer. The hydrogenated conjugated diene polymer of this embodiment preferably has a hydrogenation rate distribution, from the viewpoint of achieving a high level of balance between processability, cold flow resistance, and the ozone resistance and tensile strength of the rubber composition. When the hydrogenated conjugated diene polymer has a narrow hydrogenation rate distribution, i.e., when the hydrogenation rate is uniform or when the frequency distribution with respect to the hydrogenation rate shows a sharp peak, a method for improving the ozone resistance and tensile strength of a rubber composition using the hydrogenated conjugated diene polymer of this embodiment includes, for example, increasing the hydrogenation rate, as described in International Publication No. 2014 / 133097. On the other hand, when the hydrogenation rate of the hydrogenated conjugated diene polymer is high, the Mooney viscosity of the hydrogenated conjugated diene polymer increases too much, and processability tends to deteriorate. Reducing the molecular weight is considered to ensure good processability, but reducing the molecular weight leads to a decrease in tensile strength when the rubber composition is formed, making it difficult to achieve both of these physical properties.

[0030] On the other hand, when the distribution of the hydrogenation degree of the hydrogenated conjugated diene polymer is broad, that is, when the frequency distribution with respect to the hydrogenation degree shows a broad peak, a low hydrogenation degree component that is excellent in processability and crosslinkability and a high hydrogenation degree component that is excellent in ozone resistance and tensile properties when made into a rubber composition coexist, and therefore these physical properties can be well balanced.

[0031] Furthermore, when compared at the same average hydrogenation degree, hydrogenated conjugated diene polymers having such a wide hydrogenation degree distribution tend to provide rubber compositions with better ozone resistance than hydrogenated conjugated diene polymers having a narrow hydrogenation degree distribution. This is thought to be because components having many units derived from ethylene structures in the molecular chain, such as high-hydrogenation components, have lower surface free energy than low-hydrogenation components, and therefore tend to segregate on the surface of the rubber composition when the hydrogenated conjugated diene polymer is made into a rubber composition. When the hydrogenated conjugated diene polymer is made into a vulcanized product, this segregation acts like a protective film on the vulcanized product, preventing ozone from penetrating into the vulcanized product and preventing deterioration of the vulcanized product.

[0032] The hydrogenation degree distribution of a hydrogenated conjugated diene polymer can be indirectly evaluated by the following method. Specifically, the hydrogenation degree distribution of a hydrogenated conjugated diene polymer can be evaluated by analyzing the half-width temperature of the elution amount peak from the elution profile of the hydrogenated conjugated diene polymer obtained by temperature gradient interaction chromatography (TGIC). Specifically, because the porous graphite carbon column used in TGIC exhibits strong interaction with ethylene structures, components with a higher amount of ethylene structures require a higher temperature for elution from the column. A case will be described in which styrene is used as the aromatic vinyl compound and butadiene is used as the conjugated diene compound. Specifically, assuming that the hydrogenated conjugated diene polymer of this embodiment is a random copolymer of butadiene and styrene, the amount of ethylene structures formed by hydrogenation of the 1,4-bonds of butadiene units, which are conjugated diene monomer units in the conjugated diene polymer, correlates with the elution temperature measured by TGIC. The higher the hydrogenation degree and the higher the amount of ethylene structures, the higher the elution temperature. Conversely, the lower the hydrogenation degree and the lower the amount of ethylene structures, the lower the elution temperature. Therefore, the wider the hydrogenation degree distribution of the hydrogenated conjugated diene polymer, the broader the elution distribution obtained by TGIC and the larger the half-width temperature of the elution amount peak. Furthermore, components with a small amount of ethylene structure and weak interaction with the porous graphite carbon column will have an elution temperature below 0°C. Components with a large amount of ethylene structure and strong interaction with the porous graphite carbon column will have an elution temperature of 0°C or higher and 160°C or lower, and an elution amount peak temperature of 0°C or higher and 160°C or lower, although this is not particularly limited. When the conjugated diene polymer contains a 1,2-vinyl bond derived from butadiene (a conjugated diene compound), the structure formed by hydrogenating the butadiene-derived 1,2-vinyl bond (hereinafter referred to as a butylene structure) exhibits relatively low or no interaction with the porous graphite carbon column used in TGIC compared to the ethylene structure. Therefore, the hydrogenation degree distribution analyzed by TGIC is presumed to more specifically represent the distribution of ethylene structures.Furthermore, the aromatic vinyl compound is not limited to styrene, and the conjugated diene compound is not limited to butylene as long as it has an ethylene structure or generates an ethylene structure after hydrogenation, and the hydrogenation rate distribution or the ethylene structure distribution can be evaluated by TGIC.

[0033] When the hydrogenation degree distribution of the hydrogenated conjugated diene polymer of this embodiment is evaluated by the half-width temperature of the elution amount peak measured by TGIC described above, the half-width temperature of the elution amount peak measured by TGIC is 20° C. or higher, preferably 22° C. or higher, more preferably 24° C. or higher, even more preferably 27° C. or higher, and still more preferably 30° C. or higher, from the viewpoint of achieving a high level of balance between the processability and cold flow resistance of the hydrogenated conjugated diene polymer and rubber composition of this embodiment, and the ozone resistance and tensile strength of the rubber composition. A half-width temperature of the elution amount peak measured by TGIC of 20° C. or higher means that the hydrogenation degree distribution of the hydrogenated conjugated diene polymer of this embodiment is relatively wide, and it is possible to achieve a balance between the processability and cold flow resistance of the hydrogenated conjugated diene polymer and rubber composition of this embodiment, and the ozone resistance and tensile strength of the rubber composition. Furthermore, from the viewpoint of fully exhibiting the ozone resistance and tensile strength of the rubber composition, the half-width temperature of the elution amount peak measured by TGIC is 80° C. or less, preferably 75° C. or less, more preferably 70° C. or less, even more preferably 65° C. or less, and still more preferably 60° C. or less. By setting the half-width temperature of the elution amount peak measured by TGIC to 80° C. or less, components with a very low hydrogenation rate are less likely to be included, and the ozone resistance and tensile strength of the rubber composition can be fully exhibited.

[0034] The molecular weight distribution of the hydrogenated conjugated diene polymer has almost no effect on the half-width temperature of the elution amount peak measured by TGIC described above. This is because, when the hydrogenated conjugated diene polymer of this embodiment contains the aromatic vinyl monomer unit, it is a random polymer, and the molecular weight itself has no or little effect on the elution temperature. The half-width temperature of the elution amount peak measured by TGIC can be controlled to fall within the above-mentioned numerical range, for example, by adjusting the distribution of 1,2-bonds and 1,4-bonds and the distribution of the hydrogenation rate of the hydrogenated conjugated diene polymer of this embodiment. Specific examples include a method of imparting a distribution to the 1,2-bonds and 1,4-bonds, and a method of imparting a distribution to the hydrogenation rate of the hydrogenated conjugated diene polymer of this embodiment, as described below.

[0035] [Method for Producing Hydrogenated Conjugated Diene Polymer] The hydrogenated conjugated diene polymer of this embodiment can be produced, for example, by a method including a polymerization step of polymerizing a conjugated diene compound and an aromatic vinyl compound, and a hydrogenation step of subjecting the conjugated diene polymer obtained in the polymerization step to a hydrogenation reaction. When the hydrogenated conjugated diene polymer of this embodiment has an ethylene structure, a hydrogenation step may be carried out to form the ethylene structure, or ethylene may be copolymerized in the polymerization step. Furthermore, even when ethylene is copolymerized in the polymerization step, the hydrogenation step may be carried out. Furthermore, a modification step, which will be described later, may be carried out as necessary.

[0036] (Polymerization step) In the polymerization step, a polymer having a weight average molecular weight of 10 × 10 ４ Above 200 x 10 ４ A conjugated diene polymer having an aromatic vinyl monomer block content of less than 10% by mass is polymerized as follows. The weight-average molecular weight can be controlled within the above-mentioned range by adjusting polymerization conditions such as the amount of polymerization initiator added, the amount of monomer added, and the polymerization time in the polymerization step. The aromatic vinyl block content can be controlled within the above-mentioned range by adjusting the timing and amount of addition of the aromatic vinyl compound and the amount of randomizer added in the polymerization step.

[0037] The polymerization step can be carried out by a solution polymerization method. The monomer concentration in the solution is preferably 5% by mass or more, more preferably 10% by mass or more. When the monomer concentration in the solution is 5% by mass or more, the amount of the obtained conjugated diene-based polymer tends to be large, and costs tend to be reduced. Furthermore, the monomer concentration in the solution is preferably 50% by mass or less, more preferably 30% by mass or less. When the monomer concentration in the solution is 50% by mass or less, the solution viscosity tends to be further reduced, stirring efficiency is improved, and polymerization tends to be easier.

[0038] When anionic polymerization is carried out in the polymerization step, the polymerization initiator is not particularly limited, but an organolithium compound is preferably used. Examples of organolithium compounds include, but are not limited to, ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, tert-octyllithium, n-decyllithium, phenyllithium, 2-naphthyllithium, 2-butylphenyllithium, 4-phenylbutyllithium, cyclohexyllithium, cyclopentyllithium, and a reaction product of diisopropenylbenzene and butyllithium. Among these, compounds having an alkyl group having 2 to 20 carbon atoms are preferred, and n-butyllithium or sec-butyllithium is preferred from the viewpoints of availability, safety, and the like.

[0039] In addition, when coordination polymerization is performed in the polymerization step, it is preferable to use the polymerization catalyst composition described in JP-A-2020-45500 as the polymerization initiator.

[0040] The method for producing a conjugated diene polymer by anionic polymerization or coordination polymerization using a polymerization initiator is not particularly limited, and a conventionally known method can be used. Specifically, the target conjugated diene polymer can be obtained by polymerizing styrene, 1,3-butadiene, ethylene, or the like in an organic solvent inert to the reaction, for example, a hydrocarbon solvent such as an aliphatic, alicyclic, or aromatic hydrocarbon compound, using, for example, butyllithium as a polymerization initiator, and optionally in the presence of a predetermined randomizer.

[0041] The hydrocarbon solvent is preferably a hydrocarbon solvent having 3 to 8 carbon atoms. Examples include, but are not limited to, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis-2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, and ethylbenzene. These may be used alone or in combination of two or more.

[0042] The randomizer is a compound that has the effect of controlling the microstructure of the conjugated diene portion in a conjugated diene polymer, for example, by increasing 1,2-vinyl bonds in butadiene or 3,4-bonds in isoprene, or of controlling the composition distribution of monomer units in a conjugated diene polymer, for example, by randomizing styrene units and butadiene units in a styrene-butadiene copolymer.

[0043] The randomizer is not particularly limited, and any known compound commonly used as a conventional randomizer can be used. Examples of the randomizer include, but are not limited to, ethers and tertiary amines such as dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, 2,2-di(2-tetrahydrofuryl)propane, triethylamine, pyridine, N-methylmorpholine, N,N,N',N'-tetramethylethylenediamine, and 1,2-dipiperidinoethane. Potassium salts such as potassium t-amylate and potassium t-butoxide, and sodium salts such as sodium t-amylate can also be used. These randomizers may be used alone or in combination of two or more.

[0044] The amount of randomizer used is preferably 0.01 molar equivalents or more, more preferably 0.05 molar equivalents or more, per mole of polymerization initiator. Randomization tends to be easier when the amount of randomizer used is 0.01 molar equivalents or more per mole of polymerization initiator. The amount of randomizer used is preferably 1000 molar equivalents or less, more preferably 500 molar equivalents or less, per mole of polymerization initiator. When the amount of randomizer used is 1000 molar equivalents or less per mole of polymerization initiator, changes in the reaction rate of the monomers tend to be small, and randomization tends to be less difficult.

[0045] The reaction temperature during the polymerization step is not particularly limited as long as the reaction proceeds smoothly, but is usually preferably 10°C to 130°C, more preferably 25°C to 110°C.

[0046] (Modification Step) Furthermore, the method for producing a hydrogenated conjugated diene polymer according to this embodiment may include a modification step of modifying the obtained conjugated diene polymer after the polymerization step. When the modification step is carried out, it is preferable to convert the polymerization terminals to conjugated diene monomer units by adding a conjugated diene compound at the end of the polymerization step. This tends to make the reaction by the modifier proceed more smoothly.

[0047] The modification step is, for example, a step of reacting the active terminal of the conjugated diene polymer obtained by the polymerization step with a compound having a functional group that interacts with silica and / or carbon black. The modification step allows a functional group that interacts with silica and / or carbon black to be introduced into the polymerization terminal of the conjugated diene polymer, thereby obtaining a conjugated diene polymer with a modified polymerization terminal. The term "terminal" refers to a portion present at the end of the molecular chain other than the structure derived from a monomer having a carbon-carbon double bond.

[0048] In the modification step, the active terminal of the conjugated diene polymer obtained in the polymerization step is reacted with a compound having a functional group that interacts with silica and / or carbon black. Furthermore, by carrying out polymerization using a polymerization initiator having a functional group in the molecule that interacts with silica and / or carbon black, a functional group can be introduced into the initiation terminal of the conjugated diene polymer. Furthermore, functional groups can be introduced into both the initiation terminal and the termination terminal, as necessary.

[0049] The conjugated diene polymer used in the modification reaction (hereinafter also referred to as "terminal modification reaction") may be one whose polymerization initiation terminal is unmodified or one whose polymerization initiation terminal is modified, so long as it has an active terminal. The compound having a functional group is not particularly limited as long as it has a functional group that interacts with silica and / or carbon black and can react with the active terminal of the conjugated diene polymer. A specific modification reaction using the conjugated diene polymer and the compound having a functional group is preferably a method of introducing a functional group into the conjugated diene polymer using a terminal modifying agent containing a tin atom or a nitrogen atom, and more preferably a method of introducing a functional group into the conjugated diene polymer using a terminal modifying agent containing a nitrogen atom.

[0050] As the nitrogen atom-containing terminal modifier, from the viewpoint of polymerization productivity and a high modification rate, for example, isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen group-containing carbonyl compounds, nitrogen group-containing vinyl compounds, nitrogen group-containing epoxy compounds, nitrogen group-containing alkoxysilane compounds, cyclic urea compounds, etc. are preferred. In particular, from the viewpoint of polymerization productivity, a high modification rate, and reinforcing properties with fillers, nitrogen group-containing alkoxysilane compounds and cyclic urea compounds are more preferred. These modifiers may be used alone or in combination of two or more.

[0051] 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.

[0052] Examples of the cyclic urea compound include, but are not limited to, 1,3-diethyl-2-imidazolinone, 1,3-dimethyl-2-imidazolinone, 1,3-dipropyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 1-methyl-3-propyl-2-imidazolinone, 1-methyl-3-butyl-2-imidazolinone, 1,3-dihydro-1,3-dimethyl-2H-imidazol-2-one, 1,3-diethyl-2-imidazolidinone, 1,3-dimethyl-2-imidazolidinone, 1,3-dipropyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-propyl-2-imidazolidinone, and 1-methyl-3-butyl-2-imidazolidinone.

[0053] The terminal modification reaction of the conjugated diene polymer can be carried out, for example, as a solution reaction. This solution reaction may be carried out using a solution containing unreacted monomers after the polymerization reaction in the polymerization step has been completed, or the conjugated diene polymer contained in the solution may be isolated and dissolved in a predetermined solvent such as cyclohexane before the reaction. The terminal modification reaction may be carried out batchwise or continuously, or a combination thereof. In this case, the method of adding the terminal modifier is not particularly limited, and may be any of a method of adding all at once, a method of adding in portions, a method of adding continuously, or the like.

[0054] The amount of the terminal modifier used in the terminal modification reaction may be appropriately determined depending on the type of the terminal modifier used in the reaction, but is preferably 0.1 molar equivalents or more, more preferably 0.3 molar equivalents or more, relative to the metal atoms of the polymerization initiator involved in the polymerization reaction. By using an amount of 0.1 molar equivalents or more, the modification reaction can be sufficiently progressed, and the agent can favorably interact with filler components such as silica and carbon black, thereby favorably improving the dispersibility of the filler components.

[0055] The temperature of the terminal modification reaction is usually the same as the temperature of the polymerization reaction described above, and is preferably −20 to 150° C., more preferably 0 to 120° C., and even more preferably 20 to 100° C. The higher the temperature of the modification reaction, the lower the viscosity of the modified conjugated diene polymer tends to be. On the other hand, the lower the temperature of the modification reaction, the less likely the active terminals are to be deactivated. The reaction time of the modification reaction is preferably 5 seconds to 1 hour, more preferably 10 seconds to 45 minutes, and even more preferably 15 seconds to 30 minutes.

[0056] (Reaction Termination in Polymerization Step) The polymerization step in the above-described method for producing a hydrogenated conjugated diene polymer can be terminated by adding a reaction terminator commonly used in this field. Examples of such reaction terminators include alcohols such as methanol, ethanol, and isopropanol; polar solvents having an active proton such as acetic acid; and mixtures thereof, or mixtures of the above polar solvents with nonpolar solvents such as hexane and cyclohexane. The amount of reaction terminator added is usually preferably about the same molar amount as the polymerization initiator to about 2 times the molar amount.

[0057] (Hydrogenation Step) The hydrogenation step in the method for producing a hydrogenated conjugated diene polymer of this embodiment is not particularly limited in terms of the hydrogenation method or reaction conditions, and can be carried out by a known method and under known conditions. Typically, the hydrogenation reaction can be carried out at 20 to 150°C under a hydrogen pressure of 0.1 to 10 MPa in the presence of a hydrogenation catalyst. The hydrogenation rate of the hydrogenated conjugated diene polymer of this embodiment can be controlled by adjusting the amount and type of the hydrogenation catalyst, the hydrogen pressure during the hydrogenation reaction, the reaction time, etc.

[0058] The hydrogenation reaction process may be either a batch process or a continuous process, or a combination thereof, but it is necessary to impart a distribution to the hydrogenation rate in order to control the half-width temperature of the elution amount peak of the hydrogenated conjugated diene polymer of this embodiment, as measured by TGIC, within the range of 20 to 80° C. Examples of methods for imparting a distribution to the hydrogenation rate distribution include a method of obtaining multiple types of hydrogenated conjugated diene polymers with different hydrogenation rates and then mixing these multiple types of hydrogenated conjugated diene copolymers, and a method of performing the hydrogenation step as a continuous process and controlling the residence time distribution in a reactor in which the hydrogenation step is carried out.

[0059] When a plurality of types of hydrogenated conjugated diene polymers having different hydrogenation rates are obtained and then mixed, the hydrogenation rate distribution HWD of the resulting hydrogenated conjugated diene polymer can be expressed by the following formula (1).

[0060]

[0061] In the formula (1), n ​​represents the total number of components of hydrogenated conjugated diene polymers having different hydrogenation rates, and w ｉ is a specific hydrogenation rate H ｉ represents the mass fraction of the hydrogenated conjugated diene polymer having the formula (I) in the total hydrogenated conjugated diene polymer.

[0062] (Mixing Step) In the method for producing a hydrogenated conjugated diene polymer according to this embodiment, hydrogenated conjugated diene polymers having different hydrogenation rates are mixed. The hydrogenation distribution HWD and the half-width temperature of the elution amount peak measured by TGIC of the resulting hydrogenated conjugated diene polymer depend on the microstructure, the predetermined reference hydrogenation rate, and the mixing ratio of the hydrogenated conjugated diene polymers having different hydrogenation rates. For example, when a conjugated diene polymer having a styrene content of 8% by mass and a 1,2-vinyl bond content of 40% is hydrogenated and hydrogenated conjugated diene polymers having hydrogenation rates different by 20% from the reference hydrogenation rate are mixed in equal amounts on the high and low hydrogenation sides, the hydrogenation distribution HWD is 1.02 to 1.1, and the half-width temperature of the elution amount peak measured by TGIC is about 25 to 50°C. Furthermore, when a conjugated diene polymer similar to that described above is hydrogenated and hydrogenated conjugated diene polymers having hydrogenation rates that are changed by 10% on the high and low hydrogenation sides relative to a predetermined reference hydrogenation rate are mixed in equal amounts, the hydrogenation rate distribution HWD is 1.005 to 1.02, and the half-width temperature of the elution amount peak measured by TGIC is about 21 to 40° C. By employing a method that broadens the hydrogenation rate distribution, the half-width temperature of the elution amount peak of the hydrogenated conjugated diene polymer measured by TGIC can be controlled to 20 to 80° C. Specifically, a reference hydrogenation rate is set to 75%, and hydrogenated conjugated diene polymers having hydrogenation rates that are 20% higher and 20% lower than the reference hydrogenation rate are mixed in equal amounts, and the hydrogenation rate distribution is broadened by the method described below, thereby making it possible to set the hydrogenation rate distribution HWD to 1.005 or more and control the half-width temperature of the elution amount peak measured by TGIC to 20 to 80° C. By setting the hydrogenation rate distribution HWD to 1.005 or more and controlling the half-width temperature of the elution amount peak measured by TGIC of the hydrogenated conjugated diene polymer to a value range of 20 to 80° C., a hydrogenated conjugated diene polymer that has a high level of balance between cold flow resistance, ozone resistance, and tensile strength tends to be obtained.

[0063] When the hydrogenation step is carried out as a continuous process, the distribution width of the hydrogenation rate of the hydrogenated conjugated diene polymer produced can be controlled by adjusting the solution viscosity, the amount of solution in the reactor, and the stirring conditions, or by changing the number of inlets for feeding the conjugated diene polymer to the continuous hydrogenation reactor and thereby changing the flow path through which the conjugated diene polymer passes, thereby adjusting the reaction time distribution (residence time distribution). An index of the reaction time distribution (residence time distribution) is the value N when the degree of mixing is represented by a perfect mixing tank series model in which N perfect mixing tanks of equal volume are connected in series. It is preferable to reduce the value N to approach perfect mixing. Specifically, perfect mixing can be approached by reducing the value N by reducing the solution viscosity, increasing the stirring speed, or reducing the value H / D, which is the ratio of the liquid level height (H) to the reactor diameter (D). More specifically, when the hydrogenation step is carried out in a continuous process, by setting the number N of perfect mixing vessel rows to 1.0 to 2.5 when fitting the residence time distribution in the reactor to a perfect mixing vessel row model by the impulse response method, the hydrogenation degree distribution HWD of the produced hydrogenated conjugated diene polymer can be made 1.005 or more, the half-width temperature of the elution amount peak measured by TGIC of the hydrogenated conjugated diene polymer can be controlled within a numerical range of 20 to 80°C, and a hydrogenated conjugated diene polymer having a high level of balance between cold flow resistance, ozone resistance and tensile strength can be obtained.

[0064] In addition to the above-mentioned methods, methods for adjusting the reaction time distribution and increasing the value of the hydrogenation degree distribution HWD include, for example, methods (1) and (2). Method (1): A method in which hydrogen and a conjugated diene polymer are supplied from opposite directions to a reactor in which a hydrogenation step is performed. Method (2): A method in which hydrogen and / or a conjugated diene polymer are supplied from multiple locations.

[0065] In the case of the method (1), for example, a more preferred method for widening the reaction time distribution of the hydrogenation reaction so as to broaden the hydrogenation degree distribution HWD is to supply a conjugated diene polymer solution and a hydrogenation catalyst from the top of the stirred tank reactor, continuously supply hydrogen from the bottom of the stirred tank reactor while stirring, and extrude the solution from the bottom of the stirred tank reactor by continuous supply. In the case of the method (2), for example, a preferred method for widening the reaction time distribution of the hydrogenation reaction is to provide a reactor in a continuous hydrogenation reaction process with multiple supply ports for the conjugated diene polymer, continuously supply 80% of the total amount of the polymer from the top of the reactor, continuously supply 20% of the total amount from the middle of the reactor, and continuously remove the entire amount of the polymer after the hydrogenation reaction from the bottom of the reactor.

[0066] In the above methods (1) and (2), the value of N in the above-mentioned perfect mixing tank train model will be about 1.0 to 1.8, although it depends on the L / D (L: height of the reactor, D: diameter of the reactor) of the reactor in which the hydrogenation reaction is carried out, the shape and rotation speed of the stirring blade, and the solution viscosity. The half-width temperature of the elution amount peak of the obtained hydrogenated conjugated diene polymer measured by TGIC will be about 25 to 80°C, although it depends on the microstructure, the standard hydrogenation rate, etc.

[0067] Alternatively, in the continuous process of the hydrogenation step, a stirred tank reactor may be used, and a conjugated diene polymer solution, a homogeneous hydrogenation catalyst, and hydrogen may be continuously supplied to the bottom of the stirred tank reactor while being stirred, thereby filling the inside of the stirred tank reactor, and the hydrogenated conjugated diene polymer may be extruded from the top of the stirred tank reactor by continuously supplying the polymer solution, the hydrogenation catalyst, and hydrogen.

[0068] Specific methods for adjusting stirring conditions to widen the reaction time distribution of the hydrogenation reaction include a method using a stirred tank reactor as a back-mix reactor in which the contents are vigorously mixed with an agitator, preferably a method using a complete mixing reactor. According to this method, the number N when the continuous hydrogenation reaction process is represented by a complete mixing tank train can be reduced, and the reaction time distribution can be widened, thereby producing a hydrogenated conjugated diene polymer with a wide hydrogenation rate distribution. As fitting to calculate the number N of complete mixing tank trains, known methods such as the impulse response method and step response method described in the Chemical Engineering Handbook can be used.

[0069] The hydrogenation catalyst can typically be a compound containing any of the metals of Groups 4 to 11 of the Periodic Table. For example, compounds containing Ti, V, Co, Ni, Zr, Ru, Rh, Pd, Hf, Re, or Pt atoms can be used. More specific examples of the hydrogenation catalyst include metallocene compounds of Ti, Zr, Hf, Co, Ni, Pd, Pt, Ru, Rh, Re, or the like; supported heterogeneous catalysts in which metals such as Pd, Ni, Pt, Rh, or Ru are supported on a support such as carbon, silica, alumina, or diatomaceous earth; homogeneous Ziegler-type catalysts in which an organic salt or acetylacetone salt of a metal element such as Ni or Co is combined with a reducing agent such as organoaluminum; organometallic compounds or complexes of Ru, Rh, or the like; and hydrogen-absorbed fullerenes or carbon nanotubes.

[0070] Among these, metallocene compounds containing any one of Ti, Zr, Hf, Co, and Ni are preferred because they can undergo a hydrogenation reaction in a homogeneous system in an inert organic solvent. Metallocene compounds containing any one of Ti, Zr, and Hf are more preferred. The hydrogenation catalysts may be used alone or in combination of two or more.

[0071] A preferred method for obtaining a hydrogenated conjugated diene polymer is to carry out solution polymerization, and then subject the resulting polymer solution to a modification treatment as is, followed by a hydrogenation step as necessary. Since the solution viscosity generally increases due to the hydrogenation reaction, a step of diluting the solution with a solvent to previously reduce the solution viscosity may be added depending on the process to be applied.

[0072] (Solvent Removal Step) The hydrogenated conjugated diene polymer is obtained by removing the solvent from the polymer solution obtained above and isolating the polymer. Examples of the method for isolating the hydrogenated conjugated diene polymer include a known solvent removal method such as steam stripping, and a drying method such as heat treatment using a dehydrating extruder, a drying extruder, or a conveyor.

[0073] [Rubber Composition] The hydrogenated conjugated diene polymer of the present embodiment can be combined with other polymers, filler components, plasticizer components, crosslinking agent components, etc. to form a rubber composition having desired properties.

[0074] Examples of other polymers include, but are not limited to, natural rubber (NR), isoprene rubber (IR), styrene butadiene rubber (SBR), butadiene rubber (BR), etc. These may be used alone or in combination of two or more.

[0075] The filler component is compounded into the rubber composition for the purpose of reinforcing the rubber, and includes, but is not limited to, white fillers (inorganic fillers) such as silica, calcium carbonate, mica, aluminum hydroxide, magnesium oxide, magnesium hydroxide, clay, talc, alumina, titanium oxide, and mica, as well as carbon black. These may be used alone or in combination of two or more. Silica and carbon black are particularly preferred.

[0076] From the viewpoint of tensile strength of the rubber composition, the content of the filler is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, per 100 parts by mass of the rubber component comprising the hydrogenated conjugated diene-based polymer of the present embodiment and other polymers. When silica is used as the filler, from the viewpoint of processability and low hysteresis loss, the content of silica is preferably 120 parts by mass or less, more preferably 100 parts by mass or less.

[0077] The silica is not particularly limited, and examples thereof include dry process silica (anhydrous silica) and wet process silica (hydrated silica), but wet process silica is preferred because it contains many silanol groups.

[0078] Silica has a nitrogen adsorption specific surface area (N ２ From the viewpoint of the abrasion resistance of the rubber composition, SA) is preferably 60 m ２ / g or more, more preferably 120m ２ / g or more, and from the viewpoint of fuel economy of the rubber composition, it is preferably 300 m ２ / g or less, more preferably 200m ２ The nitrogen adsorption specific surface area of ​​silica is a value measured by the BET method in accordance with ASTM D3037-81.

[0079] Examples of carbon black include, but are not limited to, furnace blacks (furnace carbon blacks) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal blacks (thermal carbon blacks) such as FT and MT; channel blacks (channel carbon blacks) such as EPC, MPC, and CC; and graphite. These may be used alone or in combination of two or more.

[0080] The nitrogen adsorption specific surface area of ​​carbon black (N ２ SA) is usually 5 to 200 m ２ / g, and from the viewpoint of the abrasion resistance of the rubber composition, it is preferably 30m ２ / g or more, more preferably 50m ２ / g or more, and from the viewpoint of fuel economy of the rubber composition, it is preferably 150 m ２ / g or less, more preferably 120m ２ The nitrogen adsorption specific surface area of ​​carbon black is measured in accordance with ASTM D4820-93.

[0081] The dibutyl phthalate (DBP) absorption of carbon black is usually 5 to 300 mL / 100 g, preferably 80 mL / 100 g or more and 180 mL / 100 g or less. The DBP absorption of carbon black is measured in accordance with ASTM D2414-93.

[0082] Silica is preferably used in combination with a silane coupling agent. As the silane coupling agent, a conventionally known agent can be used. Examples include, but are not limited to, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(3-triethoxysilylpropyl)trisulfide, bis(3-trimethoxysilylpropyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, and bis(3-trimethoxysilylpropyl)disulfide. sulfide-based silane coupling agents such as 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-trimethoxysilylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazole tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptopropyltriethoxysilane, mercapto-based compounds such as 2-mercaptoethyltrimethoxysilane and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane and 3-(2-aminoethyl)aminopropyltrimethoxysilane; γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, Examples thereof include glycidoxy-based silane coupling agents such as propyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 2-chloroethyltrimethoxysilane, and 2-chloroethyltriethoxysilane.The silane coupling agent may be used alone or in combination of two or more. From the viewpoints of the coupling effect, processability, and cost of the silane coupling agent, sulfide-based silane coupling agents are preferred, with bis(3-triethoxysilylpropyl)tetrasulfide and bis(3-triethoxysilylpropyl)disulfide being more preferred. From the viewpoints of fuel economy and abrasion resistance of the rubber composition, the content of the silane coupling agent is preferably 3 parts by mass or more, and more preferably 5 parts by mass or more, per 100 parts by mass of silica. From the viewpoints of processability and cost of the rubber composition, the content of the silane coupling agent is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of silica.

[0083] Examples of the plasticizer component include, but are not limited to, extender oil, resins other than the above-mentioned other polymers, antioxidants, waxes, stearic acid, vulcanization accelerators, etc. These may be used alone or in combination of two or more.

[0084] The extender oil is not limited to the following, but examples thereof include aromatic mineral oil (viscosity specific gravity constant (V.G.C. value) 0.900 to 1.049), naphthenic mineral oil (V.G.C. value 0.850 to 0.899), and paraffinic mineral oil (V.G.C. value 0.790 to 0.849). The polycyclic aromatic content of the extender oil is preferably less than 3 mass%, more preferably less than 1 mass%. The polycyclic aromatic content of the extender oil can be measured according to the British Petroleum Institute 346 / 92 method. The aromatic compound content (CA) of the extender oil is preferably 20 mass% or more. One type of extender oil may be used alone, or two or more types may be used in combination. From the viewpoint of the Mooney viscosity of the rubber composition, the content of the extender oil is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component. The amount of extender oil is preferably 50 parts by mass or less, and more preferably 40 parts by mass or less, per 100 parts by mass of the rubber component, from the viewpoint of low hysteresis loss and hardness of the rubber composition.

[0085] Resins other than the above-mentioned other polymers include, but are not limited to, C5 petroleum resins, C9 petroleum resins, coumarone-indene resins, indene resins, phenolic resins, and copolymers of α-methylstyrene and / or styrene. These may be used alone or in combination of two or more. In particular, coumarone-indene resins, phenolic resins (particularly terpene phenolic resins), and copolymers of α-methylstyrene and / or styrene are preferred, with copolymers of α-methylstyrene and styrene being more preferred. From the viewpoint of wet grip performance of the rubber composition, the resin content is preferably 1 part by mass or more, and more preferably 3 parts by mass or more, per 100 parts by mass of the rubber component. Furthermore, from the viewpoint of low hysteresis loss of the rubber composition, the resin content is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the rubber component.

[0086] Examples of the antioxidant include, but are not limited to, naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-phenyl-N'-isopropyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine; Examples of antioxidants include p-phenylenediamine antioxidants such as 1-phenylenediamine; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more. In particular, p-phenylenediamine antioxidants are preferred, with N-phenyl-N'-isopropyl-p-phenylenediamine being more preferred. The amount of antioxidant is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, per 100 parts by mass of the rubber component.

[0087] Examples of waxes include, but are not limited to, petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more. Petroleum waxes are particularly preferred, and paraffin wax is more preferred. The wax content is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, per 100 parts by mass of the rubber component.

[0088] As the stearic acid, conventionally known ones can be used, and examples thereof include, but are not limited to, products from NOF Corporation, NOF Corporation, Kao Corporation, Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. These may be used alone or in combination of two or more. The content of stearic acid is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, per 100 parts by mass of the rubber component.

[0089] Examples of the vulcanization accelerator include, but are not limited to, thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, dibenzothiazyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-t-butyl-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more. In particular, sulfenamide vulcanization accelerators are preferred, and N-cyclohexyl-2-benzothiazole sulfenamide is more preferred, because they provide the effects of this embodiment more favorably. It is also preferred to use a guanidine vulcanization accelerator in combination. The content of the vulcanization accelerator is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 4 parts by mass, per 100 parts by mass of the rubber component.

[0090] The crosslinking agent component is not limited to the following and can be appropriately selected depending on the purpose. Examples include sulfur-based crosslinking agents, organic peroxide-based crosslinking agents, inorganic crosslinking agents, polyamine crosslinking agents, resin crosslinking agents, sulfur compound-based crosslinking agents, and oxime-nitrosamine-based crosslinking agents. These may be used alone or in combination of two or more. In particular, sulfur-based crosslinking agents are preferred, and sulfur is more preferred, because the effects of this embodiment can be more suitably obtained. The content of the crosslinking agent in the rubber composition of this embodiment is preferably 0.1 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the rubber component. It is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1.5 parts by mass or more. It is also preferably 20 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less. This more suitably obtains the effects of this embodiment.

[0091] In addition to the various components described above, the rubber composition of this embodiment may contain various additives such as other softeners, fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants. Known softeners can be used as the other softeners. Examples of other fillers include calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. Known materials can be used as the heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, and lubricants.

[0092] (Method for Producing Rubber Composition) The rubber composition containing the hydrogenated conjugated diene-based polymer of this embodiment can be produced by a general method, for example, by kneading the components using a Banbury mixer, a kneader, an open roll, or the like, followed by vulcanization.

[0093] The present embodiment will be described in more detail below with reference to specific examples and comparative examples, but the present invention is not limited to these examples and comparative examples. Various physical properties in the examples and comparative examples were measured by the methods shown below and further evaluated by the methods described later.

[0094] [Method for measuring physical properties] (Bound styrene content of conjugated diene polymer) A measurement sample was prepared by dissolving 100 mg of the conjugated diene polymer before hydrogenation in 100 mL of chloroform. The bound styrene content (mass%) relative to 100 mass% of the conjugated diene polymer sample was measured based on the amount of absorption of ultraviolet light at a wavelength (near 254 nm) by the phenyl group of styrene. A spectrophotometer "UV-2450" manufactured by Shimadzu Corporation was used as the measuring device.

[0095] (1,2-vinyl bond amount in butadiene portion of conjugated diene polymer) A conjugated diene polymer before hydrogenation was used as a sample, and 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. －１The absorbance at a predetermined wave number was measured in the range of 100 to 1500, and the microstructure of the butadiene moiety, i.e., the 1,2-vinyl bond content (mol%) was determined according to the calculation formula of Hampton's method (method described in R.R. Hampton, Analytical Chemistry 21, 923 (1949)). The measuring device used was a Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation.

[0096] (Half-Width Temperature of Elution Amount Peak Measured by TGIC of Hydrogenated Conjugated Diene Polymer) A hydrogenated conjugated diene polymer was dissolved in orthodichlorobenzene, and the resulting solution sample was injected into a graphite carbon column as follows. The elution amount (mass%) of the sample and the temperature (°C) inside the column at that time were calculated. The elution amount at each temperature was determined from the elution temperature-elution amount curve obtained from these values. First, a column containing a packing material was heated to 140°C, and 0.2 mL of a sample solution prepared by dissolving a hydrogenated conjugated diene polymer in orthodichlorobenzene was introduced. The column temperature was then lowered to −20°C at a temperature lowering rate of 2°C / min. The column temperature was then raised to 165°C at a temperature raising rate of 2°C / min, the mobile phase flow rate was set to 0.5 mL / min, and the concentration of the sample eluted at each temperature was detected. The elution temperature-elution amount curve was then measured, and the elution amount at each temperature was determined. Apparatus: High-throughput composition distribution analyzer, CEF (manufactured by Polymer Char) Detector: IR5 MCT infrared spectrophotometer (manufactured by Polymer Char) Detection wavelength: concentration sensor CH ２ v3.42μm (2920cm －１ ), Methyl Sensor CH ３ v3.38μm (2960cm －１) Column: porous graphite carbon column, Hypercarb high temperature compatible type (manufactured by Thermo Scientific), inner diameter 4.6 mm, length 100 mm, particle size 5 μm Mobile phase: orthodichlorobenzene, BHT added Sample concentration: 8 mg / 8 mL Dissolution conditions: 150°C, 60 minutes (under nitrogen atmosphere) Sample filtration: 10 μm in-line filter Injection amount: 0.2 mL Temperature decreasing conditions: 140°C to -20°C (2°C / min), flow rate 0.0 mL / min Temperature increasing conditions: -20°C to -165°C (2°C / min), flow rate 0.5 mL / min From the obtained elution temperature-elution amount curve, the half width temperature of the elution amount peak and the temperature of the elution amount peak in the range of 0°C to 160°C were determined. (When there are multiple elution amount peaks, the highest peak point is used as the reference point.) The half-width temperatures of the elution amount peaks are shown in Tables 3 to 6 below. In the tables, "-" means that no peak area was detected.

[0097] (Hydrogenation rate of hydrogenated conjugated diene polymer) １ The integrated value of the unsaturated bond portion of the conjugated diene polymer before hydrogenation was obtained by H-NMR measurement. Next, a large amount of methanol was added to the reaction solution after the hydrogenation reaction, and the hydrogenated conjugated diene polymer was precipitated and recovered. Next, the hydrogenated conjugated diene polymer was extracted with acetone, and the hydrogenated conjugated diene polymer was vacuum dried. This was １ The hydrogenation rate was measured using the sample for H-NMR measurement. The measurement conditions are as follows. <Measurement conditions> Measurement equipment: JNM-LA400 (manufactured by JEOL) Solvent: deuterated chloroform Measurement sample: sample taken before and after hydrogenation of 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

[0098] (Content of aromatic vinyl monomer block in hydrogenated conjugated diene polymer) A chain of 8 or more styrene units is defined as a styrene block, and the content of the styrene block was determined as follows. The hydrogenated conjugated diene polymer was subjected to a 400 MHz spectrometry using deuterated chloroform as a solvent.１ The H-NMR spectrum was measured. １ From the H-NMR spectrum, the integral ratio of each chemical shift range of the following (X) was determined, and the content of the styrene block contained in the hydrogenated conjugated diene polymer was calculated.

[0099] (Amount of ethylene structure in hydrogenated conjugated diene polymer) １ The ethylene structure content of a hydrogenated conjugated diene polymer was measured by H-NMR measurement using a hydrogenated conjugated diene polymer. The conditions are as follows. <Measurement conditions> Measurement equipment: JNM-LA400 (manufactured by JEOL) Solvent: deuterated chloroform Measurement sample: hydrogenated conjugated diene polymer Sample concentration: 50 mg / mL Observation frequency: 400 MHz Chemical shift reference: TMS (tetramethylsilane) Pulse delay: 2.904 seconds Number of scans: 64 Pulse width: 45° Measurement temperature: 26°C

[0100] (Modification Ratio of Hydrogenated Conjugated Diene Polymer) The modification ratio of the hydrogenated conjugated diene polymer in the examples and comparative examples described below was measured by column adsorption GPC as follows. The measurement utilized the property of a conjugated diene polymer modified with a nitrogen atom-containing functional group to adsorb to a column. The amount of a sample solution containing a sample and a low-molecular-weight internal standard polystyrene adsorbed to the silica column was measured by subtracting the chromatogram measured using a polystyrene column from that measured using a silica column, and the modification ratio was determined. Specifically, the procedure is as follows. <Preparation of Sample Solution>: 10 mg of the measurement sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF (tetrahydrofuran) to prepare a sample solution. <GPC Measurement Conditions Using a Polystyrene Column>: THF containing 5 mmol / L of triethylamine was used as the eluent, and 20 μL of the sample solution was injected into the instrument for measurement. The columns used were: guard column: Tosoh Corporation, trade name "TSKguard column Super H-H", column: Tosoh Corporation, trade name "TSKgel Super H5000", "TSKgel Super H6000", "TSKgel Super H7000". Column oven temperature: 40 ° C., THF flow rate: 0.6 mL / min, measured using an RI detector (Tosoh Corporation, HLC8020) to obtain a chromatogram. <GPC measurement conditions using silica column>: Tosoh Corporation, trade name "HLC-8320GPC", THF was used as the eluent, 50 μL of sample solution was injected into the apparatus, and a column oven temperature of 40 ° C., THF flow rate: 0.5 ml / min, using an RI detector to obtain a chromatogram. The columns used were trade names "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S", and a guard column trade name "DIOL 4.6 x 12.5 mm 5 micron" was connected in front of them. <Method for calculating modification rate>: The entire peak area of ​​the chromatogram using the polystyrene column was set to 100, the peak area of ​​the sample was set to P1, the peak area of ​​the standard polystyrene was set to P2, and the entire peak area of ​​the chromatogram using the silica column was set to 100, the peak area of ​​the sample was set to P3, and the peak area of ​​the standard polystyrene was set to P4. The modification rate (%) was calculated using the following formula.Modification rate (%)=[1−(P2×P3) / (P1×P4)]×100 (where P1+P2=P3+P4=100).

[0101] (Weight-Average Molecular Weight of Hydrogenated Conjugated Diene Polymer) Measurement Condition 1: A conjugated diene polymer or a hydrogenated conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC measurement device (manufactured by Tosoh Corporation, trade name "HLC-8320GPC") equipped with three connected columns packed with polystyrene gel, and an RI detector (manufactured by Tosoh Corporation, trade name "HLC8020"), and the weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the sample were determined based on a calibration curve obtained using standard polystyrene. The eluent used was THF (tetrahydrofuran) containing 5 mmol / L triethylamine. Three columns, manufactured by Tosoh Corporation under the trade name "TSKgel SuperMultipore HZ-H," were connected, and a Tosoh Corporation "TSKguard column Super MP (HZ)-H" was connected in front of them as a guard column. 10 mg of the sample to be measured was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into the GPC measurement device and measured under conditions of an oven temperature of 40°C and a THF flow rate of 0.35 mL / min. Among the various samples measured under the above measurement condition 1, samples with a molecular weight distribution (Mw / Mn) value of less than 1.6 were remeasured under the following measurement condition 2, and the obtained results were used as the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the sample. Measurement Condition 2: A conjugated diene polymer or a hydrogenated conjugated diene polymer was used as a sample. A chromatogram was measured using a GPC measuring device with three columns connected together, each packed with a polystyrene gel. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the sample were determined based on a calibration curve using standard polystyrene. The eluent used was THF containing 5 mmol / L triethylamine. The columns used were a guard column manufactured by Tosoh Corporation under the trade name "TSKguardcolumn Super H-H," and columns manufactured by Tosoh Corporation under the trade names "TSKgel Super H5000," "TSKgel Super H6000," and "TSKgel Super H7000." An RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020") was used under conditions of an oven temperature of 40°C and a THF flow rate of 0.6 mL / min.10 mg of the sample to be measured was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into a GPC measurement device and measured.

[0102] [Method for evaluating properties] (Mooney viscosity (ML) of hydrogenated conjugated diene polymer) Using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.), the Mooney viscosity was measured in accordance with ISO 289. After preheating the sample at 100°C for 1 minute, the L-shaped rotor was rotated at 2 rpm, and the torque after 4 minutes was measured to determine the Mooney viscosity (ML （１＋４） ) was obtained.

[0103] (Cold Flow Resistance of Hydrogenated Conjugated Diene Polymer) A sample heated to 60°C was filled into a rectangular container with dimensions of 210 mm long, 105 mm short, and 200 mm deep, and compressed with a cylinder at a pressure of 3.5 MPa for 10 seconds to obtain a rectangular molded body. Using the obtained molded body, a 5 kg load was applied at an ambient temperature of 25°C and humidity of 50% and the thickness (H72) after 72 hours was measured. The thickness change rate (%) was calculated using the following formula, and the thickness change index was also calculated. Thickness change rate (%) = (H0 - H72) × 100 / H0 Thickness change index = (thickness change rate of reference hydrogenated conjugated diene polymer) ÷ (thickness change rate of hydrogenated conjugated diene polymer to be evaluated) × 100 H0 indicates the thickness of the sample immediately after molding. A smaller thickness change rate and a larger thickness change index indicate less cold flow of the sample during storage and better handleability. The thickness variation index of the hydrogenated conjugated diene polymer to be evaluated was evaluated according to the following criteria. The (reference hydrogenated conjugated diene polymer) is shown in Table 1 below. <Evaluation criteria> ⊚: Thickness variation index is 140 or more ◯: Thickness variation index is 120 or more and less than 140 Δ: Thickness variation index is 80 or more and less than 120 ×: Thickness variation index is less than 80

[0104] [Production of Hydrogenated Conjugated Diene Polymer] (Preparation of Hydrogenation Catalyst) The hydrogenation catalyst used in preparing the hydrogenated conjugated diene polymer in the Examples and Comparative Examples described below was prepared by the following method: 1 L of dried and purified cyclohexane was placed in a nitrogen-purged reaction vessel, and 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added. Then, with sufficient stirring, an n-hexane solution containing 200 mmol of trimethylaluminum was added, and the mixture was allowed to react at room temperature for about 3 days to obtain a hydrogenation catalyst.

[0105] Example 1 Production of Hydrogenated Conjugated Diene Polymer A1 A 40 L autoclave reactor whose interior volume had been purged with nitrogen was charged with 22,000 g of cyclohexane, 30 mmol of tetrahydrofuran (THF), 7.0 mmol of 2,2-di(2-tetrahydrofuryl)propane, 450 g of styrene, and 2,550 g of 1,3-butadiene. The temperature of the reactor contents was adjusted to 43°C, and then a cyclohexane solution containing 40.0 mmol of n-butyllithium was added to initiate polymerization, and the polymerization was carried out under adiabatic conditions.

[0106] Two minutes after the reaction temperature reached its peak, 8.0 mmol of 2,2-dimethoxy-1-(3-(trimethoxysilyl)propyl)-1,2-azasilolidine was added as a modifying agent and reacted with the active sites of the polymer for 20 minutes. Thereafter, 8.0 mmol of methanol was added to this polymer solution as a reaction terminator to obtain a conjugated diene polymer solution before hydrogenation.

[0107] In the subsequent hydrogenation reaction 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, respectively), 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 (polymer concentration 12% by mass) obtained above was fed from nozzle A at the top of the reactor at a rate such that the polymer amount was 1.7 kg / h. Further, the hydrogenation catalyst prepared as described above was added to the polymer solution in an amount of 100 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 (2), whereby the number of complete mixing vessels, N, was approximated to be 1.1.

[0108]

[0109] While maintaining the reactor conditions, hydrogen was continuously supplied to a pressure of 0.6 MPa to carry out the hydrogenation reaction. Next, 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 to the resulting hydrogenated conjugated diene polymer solution. Thereafter, an aqueous solution (temperature: 80°C) adjusted to pH 8.5 (pH at 80°C as determined by the glass electrode method; the same applies hereinafter) with ammonia, a pH adjuster, was placed in a solvent removal tank, and the hydrogenated conjugated diene polymer solution was added to the solvent removal tank (ratio of 200 parts by mass of aqueous solution to 100 parts by mass of polymer solution). The solvent was removed by steam stripping (steam temperature: 190°C) for 2 hours in the liquid phase of the solvent removal tank (temperature: 95°C). The remaining water was then dried using a dryer to obtain hydrogenated conjugated diene polymer A1. The analytical values ​​of the hydrogenated conjugated diene polymer A1 are shown in Table 3 below.

[0110] Comparative Example 1: Production of hydrogenated conjugated diene polymer A1' A nitrogen-purged autoclave reactor having an internal volume of 40 L was charged with 22,000 g of cyclohexane, 30 mmol of tetrahydrofuran (THF), 7.0 mmol of 2,2-di(2-tetrahydrofuryl)propane, 450 g of styrene, and 2,550 g of 1,3-butadiene. After adjusting the temperature of the reactor content to 43°C, a cyclohexane solution containing 40.0 mmol of n-butyllithium was added to initiate polymerization, and the polymerization was carried out under adiabatic conditions.

[0111] Two minutes after the reaction temperature reached its peak, 8.0 mmol of 2,2-dimethoxy-1-(3-(trimethoxysilyl)propyl)-1,2-azasilolidine was added as a modifying agent and reacted with the active sites of the conjugated diene polymer for 20 minutes. Thereafter, 8.0 mmol of methanol was added as a reaction terminator to this conjugated diene polymer solution to obtain a conjugated diene polymer solution before hydrogenation.

[0112] In the subsequent hydrogenation reaction step, a reactor having an internal volume of 40 L and an L / D ratio of 2.2, equipped with a rotary stirrer rotating at 114 rpm, was used. After adjusting the temperature of the reactor to 90°C, the reactor was completely filled with the conjugated diene polymer solution (polymer concentration: 12 mass%) obtained above, and the hydrogenation catalyst prepared as described above was added to the conjugated diene polymer solution in an amount of 100 ppm in terms of titanium relative to the amount of charged monomers. The hydrogenation reaction was carried out for 70 minutes while hydrogen was charged into the reactor to a pressure of 0.6 MPa. Next, 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 to the resulting polymer solution as antioxidants. The aqueous solution (temperature: 80°C) was then adjusted to pH 8.5 (pH at 80°C as determined by the glass electrode method; the same applies hereinafter) with ammonia as a pH adjuster. The resulting solution was then placed in a desolvation tank. The hydrogenated conjugated diene polymer solution was then added to the desolvation tank (200 parts by mass of aqueous solution per 100 parts by mass of polymer solution). The solvent was removed by steam stripping (steam temperature: 190°C) for 2 hours in the liquid phase of the desolvation tank (temperature: 95°C). The remaining water was then dried using a dryer to obtain hydrogenated conjugated diene polymer A1'. The analytical values ​​of hydrogenated conjugated diene polymer A1' are shown in Table 3.

[0113] Example 2: Production of hydrogenated conjugated diene polymer A2 A nitrogen-purged 40 L autoclave reactor was charged with 22,000 g of cyclohexane, 30 mmol of tetrahydrofuran (THF), 7.0 mmol of 2,2-di(2-tetrahydrofuryl)propane, and 240 g of styrene. The temperature of the reactor content was adjusted to 43°C, and then a cyclohexane solution containing 40.0 mmol of n-butyllithium was added to initiate polymerization, which was then carried out under adiabatic conditions for 10 minutes. Hydrogenated conjugated diene polymer A2 was obtained in the same manner as in Example 1, except that 210 g of styrene and 2,550 g of 1,3-butadiene were then added and polymerization was carried out under adiabatic conditions.

[0114] Comparative Example 2: Production of Hydrogenated Conjugated Diene Polymer A2' A 40 L autoclave reactor purged with nitrogen was charged with 22,000 g of cyclohexane, 30 mmol of tetrahydrofuran (THF), 7.0 mmol of 2,2-di(2-tetrahydrofuryl)propane, and 360 g of styrene. The temperature of the reactor content was adjusted to 43°C, and then a cyclohexane solution containing 40.0 mmol of n-butyllithium was added to initiate polymerization, which was then carried out under adiabatic conditions for 10 minutes. Hydrogenated Conjugated Diene Polymer A2' was obtained in the same manner as in Example 1, except that 90 g of styrene and 2,550 g of 1,3-butadiene were then added and polymerization was carried out under adiabatic conditions.

[0115] Comparative Example 3: Production of hydrogenated conjugated diene polymer A3' Hydrogenated conjugated diene polymer A3' was obtained in the same manner as in Comparative Example 1, except that the reaction time in the hydrogenation step was changed to 100 minutes.

[0116] Comparative Example 4: Production of hydrogenated conjugated diene polymer A4' Hydrogenated conjugated diene polymer A4' was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 56 mmol, n-butyllithium was 320 mmol, 2,2-dimethoxy-1-(3-(trimethoxysilyl)propyl)-1,2-azasilolidine was 64 mmol, and methanol was 64 mmol.

[0117] Comparative Example 5: Production of hydrogenated conjugated diene polymer A5' Hydrogenated conjugated diene polymer A5' was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 1.2 mmol, n-butyllithium was 6.4 mmol, 2,2-dimethoxy-1-(3-(trimethoxysilyl)propyl)-1,2-azasilolidine was 1.3 mmol, and methanol was 1.3 mmol.

[0118] Example 3 Production of Hydrogenated Conjugated Diene Polymer A3 Hydrogenated conjugated diene polymer A3 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 6.1 mmol, n-butyllithium was 35 mmol, and methanol was 35 mmol, and 2,2-dimethoxy-1-(3-(trimethoxysilyl)propyl)-1,2-azasilolidine was not added.

[0119] Comparative Example 6: Production of hydrogenated conjugated diene polymer A6′ A hydrogenated conjugated diene polymer A6′ was obtained in the same manner as in Comparative Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 6.1 mmol, n-butyllithium was 35 mmol, and methanol was 35 mmol, and 2,2-dimethoxy-1-(3-(trimethoxysilyl)propyl)-1,2-azasilolidine was not added.

[0120] Example 4 Production of Hydrogenated Conjugated Diene Polymer A4 Hydrogenated conjugated diene polymer A4 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 6.1 mmol, n-butyllithium was 35 mmol, 1,3-dimethyl-2-imidazolidinone was 28 mmol, and methanol was 7.0 mmol.

[0121] Comparative Example 7: Production of hydrogenated conjugated diene polymer A7' A hydrogenated conjugated diene polymer A7' was obtained in the same manner as in Comparative Example 1, except that the amount of 2,2-di(2-tetrahydrofuryl)propane was 6.1 mmol, the amount of n-butyllithium was 35 mmol, the amount of 1,3-dimethyl-2-imidazolidinone was 28 mmol, and the amount of methanol was 7.0 mmol.

[0122] Example 5: Production of hydrogenated conjugated diene polymer B1 Hydrogenated conjugated diene polymer B1 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 4.6 mmol, styrene was 120 g, and 1,3-butadiene was 2880 g.

[0123] Comparative Example 8: Production of hydrogenated conjugated diene polymer B1' A hydrogenated conjugated diene polymer B1' was obtained in the same manner as in Comparative Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 4.6 mmol, styrene was 120 g, and 1,3-butadiene was 2880 g.

[0124] Example 6: Production of hydrogenated conjugated diene polymer B2 Hydrogenated conjugated diene polymer B2 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were changed to 11.6 mmol, 240 g, and 2760 g, respectively.

[0125] Comparative Example 9: Production of hydrogenated conjugated diene polymer B2' Hydrogenated conjugated diene polymer B2' was obtained in the same manner as in Comparative Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were changed to 11.6 mmol, 240 g, and 2760 g, respectively.

[0126] Example 7: Production of hydrogenated conjugated diene polymer B3 Hydrogenated conjugated diene polymer B3 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were changed to 19.5 mmol, 780 g, and 2,220 g, respectively.

[0127] Comparative Example 10: Production of hydrogenated conjugated diene polymer B3' Polymer B3' was obtained in the same manner as in Comparative Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 19.5 mmol, styrene 780 g, and 1,3-butadiene 2220 g.

[0128] Example 8: Production of hydrogenated conjugated diene polymer B4 Hydrogenated conjugated diene polymer B4 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were changed to 11.6 mmol, 1200 g, and 1800 g, respectively.

[0129] Comparative Example 11: Production of hydrogenated conjugated diene polymer B4' Hydrogenated conjugated diene polymer B4' was obtained in the same manner as in Comparative Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were changed to 11.6 mmol, 1,200 g, and 1,800 g, respectively.

[0130] Example 9: Production of hydrogenated conjugated diene polymer B5 Hydrogenated conjugated diene polymer B5 was obtained in the same manner as in Example 1, except that styrene was not added and the amount of 1,3-butadiene was changed to 3,000 g.

[0131] Comparative Example 12: Production of hydrogenated conjugated diene polymer B5' Hydrogenated conjugated diene polymer B5' was obtained in the same manner as in Comparative Example 1, except that styrene was not added and the amount of 1,3-butadiene was changed to 3,000 g.

[0132] Example 10: Production of hydrogenated conjugated diene polymer C1 A hydrogenated conjugated diene polymer C1 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were changed to 11.6 mmol, 240 g, and 2760 g, respectively.

[0133] Example 11 Production of Hydrogenated Conjugated Diene Polymer C2 Hydrogenated conjugated diene polymer C2 was obtained in the same manner as in Example 1, except that the amount of 2,2-di(2-tetrahydrofuryl)propane was 11.6 mmol, the amount of styrene was 240 g, the amount of 1,3-butadiene was 2760 g, and the polymer supply rate in the hydrogenation reaction step was 1.5 kg / h.

[0134] Example 12: Production of hydrogenated conjugated diene polymer C3 Hydrogenated conjugated diene polymer C3 was obtained in the same manner as in Example 1, except that the amount of 2,2-di(2-tetrahydrofuryl)propane was 11.6 mmol, the amount of styrene was 240 g, the amount of 1,3-butadiene was 2760 g, and the polymer supply rate in the hydrogenation reaction step was 1.2 kg / h.

[0135] Example 13: Production of hydrogenated conjugated diene polymer C4 Hydrogenated conjugated diene polymer C4 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 11.6 mmol, styrene was 240 g, 1,3-butadiene was 2760 g, and the polymer supply rate in the hydrogenation reaction step was 2.7 kg / h.

[0136] Example 14: Production of hydrogenated conjugated diene polymer C5 Hydrogenated conjugated diene polymer C5 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 11.6 mmol, styrene was 240 g, 1,3-butadiene was 2760 g, and the polymer supply rate in the hydrogenation reaction step was 3.3 kg / h.

[0137] Comparative Example 13: Production of hydrogenated conjugated diene polymer C1' A hydrogenated conjugated diene polymer C1' was obtained in the same manner as in Comparative Example 1, except that the amount of 2,2-di(2-tetrahydrofuryl)propane was 11.6 mmol, the amount of styrene was 240 g, and the amount of 1,3-butadiene was 2760 g.

[0138] Comparative Example 14: Production of hydrogenated conjugated diene polymer C2' A hydrogenated conjugated diene polymer C2' was obtained in the same manner as in Comparative Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were changed to 11.6 mmol, 240 g, and 2,760 g, respectively, and the hydrogenation reaction step was not carried out.

[0139] Comparative Example 15: Production of hydrogenated conjugated diene polymer C3' A hydrogenated conjugated diene polymer C3' was obtained in the same manner as in Comparative Example 1, except that the amount of 2,2-di(2-tetrahydrofuryl)propane was 11.6 mmol, the amount of styrene was 240 g, the amount of 1,3-butadiene was 2760 g, and the reaction time of the hydrogenation step was 35 minutes.

[0140] Comparative Example 16: Production of hydrogenated conjugated diene polymer C4′ A hydrogenated conjugated diene polymer C4′ was obtained in the same manner as in Comparative Example 1, except that the amount of 2,2-di(2-tetrahydrofuryl)propane was 11.6 mmol, the amount of styrene was 240 g, the amount of 1,3-butadiene was 2760 g, and the reaction time of the hydrogenation step was 20 minutes.

[0141] Example 15: Production of hydrogenated conjugated diene polymer D1 Hydrogenated conjugated diene polymer D1 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were changed to 11.6 mmol, 240 g, and 2760 g, respectively.

[0142] Example 16: Production of hydrogenated conjugated diene polymer D2 Three types of hydrogenated conjugated diene polymers with different hydrogenation rates were obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were 11.6 mmol, styrene, and 1,760 g, the reaction times in the hydrogenation step were 81 minutes, 70 minutes, and 55 minutes, and one-third of the content was withdrawn at each reaction time. Thereafter, equal amounts of the obtained hydrogenated conjugated diene polymers were mixed to obtain hydrogenated conjugated diene polymer D2. At this time, the value of the hydrogenation rate distribution HWD was 1.01.

[0143] Example 17 Production of Hydrogenated Conjugated Diene Polymer D3 Five types of hydrogenated conjugated diene polymers with different hydrogenation rates were obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were 11.6 mmol, styrene, and 1,760 g, the reaction times for the hydrogenation step were 105 minutes, 81 minutes, 70 minutes, 55 minutes, and 42 minutes, and 1 / 5 of the content was withdrawn at each reaction time. The five hydrogenated conjugated diene polymers obtained were then mixed together to have equal contents, thereby producing hydrogenated conjugated diene polymer D3. The hydrogenation rate distribution HWD was 1.04.

[0144] Example 18 Production of Hydrogenated Conjugated Diene Polymer D4 Hydrogenated conjugated diene polymer D4 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 11.6 mmol, styrene was 240 g, and 1,3-butadiene was 2760 g, and the polymer solution was supplied from nozzle F at the bottom of the reactor and withdrawn from nozzle B at the top of the reactor in the hydrogenation step. At this time, the value of the number N of complete mixing vessels measured by the impulse response method was 2.3.

[0145] Example 19: Production of hydrogenated conjugated diene polymer D5 Hydrogenated conjugated diene polymer D5 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were 11.6 mmol, 240 g, and 2,760 g, respectively, and that the rotation speed in the hydrogenation step was 70 rpm. At this time, the value of the number N of complete mixing vessels measured by the impulse response method was 1.3.

[0146] Example 20 Production of Hydrogenated Conjugated Diene Polymer D6 Hydrogenated conjugated diene polymer D6 was obtained in the same manner as in Example 19, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 11.6 mmol, styrene 240 g, and 1,3-butadiene 2760 g, 20% of the polymer solution supplied from nozzle A at the top of the reactor in the hydrogenation step was supplied from nozzle G at the central side of the reactor, and the number of complete mixing tanks N was changed to 1.2. In this case, the value of the number of complete mixing tanks N measured by the impulse response method was 1.2.

[0147] Example 21 Production of Hydrogenated Conjugated Diene Polymer D7 Hydrogenated conjugated diene polymer D7 was obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane, styrene, and 1,3-butadiene were 11.6 mmol, 240 g, and 2,760 g, the rotation speed in the hydrogenation step was 20 rpm, the polymer supply rate was 2.3 kg / h, and the liquid level in the reactor was 80%. At this time, H / D (H: liquid level, D: reactor diameter) was 1.8, and the value of the number N of perfect mixing vessels measured by the impulse response method was 2.2.

[0148] Comparative Example 17: Production of hydrogenated conjugated diene polymer D1' Hydrogenated conjugated diene polymer D1' was obtained in the same manner as in Comparative Example 1, except that the amount of 2,2-di(2-tetrahydrofuryl)propane was 11.6 mmol, the amount of styrene was 240 g, and the amount of 1,3-butadiene was 2760 g.

[0149] Example 22 Production of Hydrogenated Conjugated Diene Polymer D8 Four types of hydrogenated conjugated diene polymers with different hydrogenation rates were obtained in the same manner as in Example 1, except that the amounts of 2,2-di(2-tetrahydrofuryl)propane were 4.6 mmol, styrene was 120 g, 1,3-butadiene was 2,880 g, and the reaction time in the hydrogenation step was changed to four levels: 90 minutes, 80 minutes, 30 minutes, and 20 minutes (one-fourth of the content was withdrawn at each time). Thereafter, the four types of hydrogenated conjugated diene polymers obtained and the hydrogenated conjugated diene polymer B1 obtained in Example 5, a total of five types of hydrogenated conjugated diene polymers, were mixed in equal amounts to obtain hydrogenated conjugated diene polymer D8.

[0150] [Evaluation of Rubber Compositions Containing Hydrogenated Conjugated Diene Polymers A1 to D1'] Rubber compositions were obtained by mixing the components according to the formulation shown in Table 2. The amount of each compounding agent added in Table 2 is shown in parts by mass relative to 100 parts by mass of the rubber component not containing a rubber softener, i.e., the hydrogenated conjugated diene polymer.

[0151] (Mixing Method) Using an internal mixer (capacity: 0.5 L) equipped with a temperature control device, materials other than sulfur and vulcanization accelerator were mixed in the first mixing stage at a filling rate of 65% and a rotor rotation speed of 50-90 rpm. The temperature of the internal mixer was controlled to obtain a compound at a discharge temperature of 150-160°C. Next, in the second mixing stage, the compound obtained above was cooled to room temperature and then mixed again to improve the dispersion of the filler, i.e., carbon black. Again, the mixer temperature was controlled to obtain a discharge temperature of 150-160°C. After cooling, in the third mixing stage, the vulcanization accelerator and sulfur were added and mixed using an open roll set at 70°C to obtain an unvulcanized rubber composition. The mixture was then molded and vulcanized in a vulcanization press at 160°C for a predetermined vulcanization time, obtaining a vulcanized rubber composition. The vulcanization time was calculated by adding 5 minutes to the 90% vulcanization time of the unvulcanized rubber composition. The vulcanized rubber compositions were evaluated by the following methods.

[0152] [Evaluation Items and Test Methods] The unvulcanized and vulcanized rubber compositions obtained were evaluated as follows, and the results are shown in Tables 3 to 6 below.

[0153] (1) Processability (Mooney Viscosity (Compound ML)) Using the unvulcanized rubber composition obtained above as a sample, a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.) was used in accordance with ISO 289 to measure the viscosity after preheating at 130°C for 1 minute and then rotating the rotor at 2 revolutions per minute for 4 minutes. The measurement result of the unvulcanized rubber composition of hydrogenated conjugated diene polymer, which served as the reference for comparison, was indexed as 100, and the results were evaluated using the following indices. The reference hydrogenated conjugated diene polymers are shown in Table 1 below. ⊚: Index less than 80 ◯: Index 80 or more but less than 90 Δ: Index 90 or more but less than 110 ×: Index 110 or more

[0154] (2) Tensile Properties The vulcanized rubber compositions obtained above were used as samples to measure tensile properties in accordance with the tensile testing method of JIS K6251. The measurement results of the vulcanized rubber compositions of hydrogenated conjugated diene polymers, which served as the reference for comparison, were indexed to 100, and the properties were evaluated using the following indices. The reference hydrogenated conjugated diene polymers are shown in Table 1 below. <Tensile strength (TB)> ◎: Index is 120 or more ○: Index is 110 or more but less than 120 △: Index is 90 or more but less than 110 ×: Index is less than 90 <Tensile elongation (EB)> ◎: Index is 120 or more ○: Index is 110 or more but less than 120 △: Index is 90 or more but less than 110 ×: Index is less than 90

[0155] (3) Ozone Resistance From the vulcanized rubber composition obtained above, strip samples (length 6 cm x width 1 cm x thickness 2.0 mm) were punched out and placed in an ozone bath (40°C, 50 pphm) and allowed to stand for 96 hours at 20% elongation. Thereafter, the strip samples (vulcanized rubber sheets) were observed, and the number of cracks present on the surface that were 1 mm or longer was counted. The number of cracks in the vulcanized rubber sheet of the hydrogenated conjugated diene polymer used as the reference for comparison was set as 100, and the resistance was evaluated using the following index. The reference hydrogenated conjugated diene polymers are shown in Table 1 below. ⊚: Index less than 60, or no cracks occurred in the vulcanized rubber sheet. ○: Index 60 or more but less than 80. Δ: Index 80 or more but less than 120. ×: Index 120 or more, or the vulcanized rubber sheet broke.

[0156] (4) Fuel Saving Performance Using a viscoelasticity tester "ARES" manufactured by Rheometrics Scientific, tan δ was measured in torsion mode at 50°C, a frequency of 10 Hz, and a strain of 3%, and used as an index of fuel saving performance. The measurement result of a vulcanized rubber composition of a hydrogenated conjugated diene polymer, which served as a reference for comparison, was set to 100, and the performance was evaluated using the following index. The reference hydrogenated conjugated diene polymers are shown in Table 1 below. ◎: Index less than 80 ○: Index 80 or more but less than 90 △: Index 90 or more but less than 110 ×: Index 110 or more

[0157] In Table 2 below, the trade names used for each component are as follows: Hydrogenated conjugated diene polymers: A1 to D1' Natural rubber: RSS No. 3 (Producer: UNIMAC RUBBER CO., LTD. (Thailand), Supplier: Marubeni Techno Rubber) Carbon black: SEAST SO (FEF) manufactured by Tokai Carbon Co., Ltd. (Nitrogen adsorption specific surface area: 42 m 2 / g) Softener: Process oil PF30 (SRAE oil) manufactured by JXTG Nippon Oil & Energy Corporation Zinc oxide: Zinc oxide manufactured by Sakai Chemical Industry Co., Ltd. Stearic acid: Lunac S-90V manufactured by Kao Corporation Wax: Sunnock manufactured by Ouchi Shinko Chemical Co., Ltd. Anti-aging agent: Nocrac 6C manufactured by Ouchi Shinko Chemical Co., Ltd. Sulfur: Powdered sulfur Sulfax 200S manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator: TBBS Suncerer NS-G (N-tert-butylbenzothiazole-2-sulfenamide) manufactured by Sanshin Chemical Co., Ltd.

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[0159]

[0160]

[0161]

[0162]

[0163]

[0164] From Tables 3 to 6, it was confirmed that the polymers of Examples 1 to 22 were superior in processability and cold flow resistance compared with the "reference hydrogenated conjugated diene polymers" shown in Table 1, and when made into rubber compositions, were superior in ozone resistance and break physical properties.

[0165] As described above, it has become clear that the present invention can provide a hydrogenated conjugated diene polymer that ensures the processability and cold flow resistance of a hydrogenated conjugated diene polymer and a rubber composition using the same, and that, when made into a rubber composition, has excellent ozone resistance, physical properties at break, and low hysteresis loss.

[0166] This application is based on a Japanese patent application (Patent Application No. 2024-069920) filed with the Japan Patent Office on April 23, 2024, the contents of which are incorporated herein by reference.

[0167] The present invention has industrial applicability, for example, in casings such as tire treads and sidewalls, packings and 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 hydrogenated conjugated diene polymer satisfying the following conditions (i) to (iii): <Condition (i)> The polymer contains conjugated diene monomer units and may contain aromatic vinyl monomer units, and when the aromatic vinyl monomer units are contained, the polymer is a random polymer, and the content of the aromatic vinyl monomer blocks is less than 10% by mass of the hydrogenated conjugated diene polymer. <Condition (ii)> The weight average molecular weight is 10 x 10 ４ Above 200 x 10 ４ <Condition (iii)> The half-width temperature of the elution amount peak measured by temperature gradient interaction chromatography is in the range of 20 to 80°C.

2. The hydrogenated conjugated diene polymer according to claim 1, having a hydrogenation rate of 97 mol % or less.

3. The hydrogenated conjugated diene polymer according to claim 1, having a hydrogenation rate of 50 mol % or more.

4. The hydrogenated conjugated diene polymer according to claim 1, which has an ethylene structure, and the ethylene structure accounts for 1 mass % or more.

5. The hydrogenated conjugated diene polymer according to claim 1, which contains an aromatic vinyl monomer unit.

6. A method for producing the hydrogenated conjugated diene polymer according to any one of claims 1 to 5, wherein the weight average molecular weight is 10 x 10 ４ Above 200 x 10 ４ The method for producing a hydrogenated conjugated diene polymer comprises: a polymerization step of obtaining a conjugated diene polymer having an aromatic vinyl monomer block content of less than 10% by mass; a hydrogenation step of obtaining a plurality of types of hydrogenated conjugated diene polymers having different hydrogenation rates; and a mixing step of mixing the plurality of types of hydrogenated conjugated diene polymers to make the hydrogenation rate distribution HWD, represented by the following formula (1), 1.005 or more. (In formula (1), n ​​represents the total number of components of hydrogenated conjugated diene polymers having different hydrogenation rates, and w ｉ is a specific hydrogenation rate H ｉ represents the mass fraction of the hydrogenated conjugated diene polymer having the formula (I) in the total hydrogenated conjugated diene polymer.

7. A method for producing the hydrogenated conjugated diene polymer according to any one of claims 1 to 5, wherein the weight average molecular weight is 10 x 10 ４ Above 200 x 10 ４ A method for producing a hydrogenated conjugated diene polymer, comprising: a polymerization step of obtaining a conjugated diene polymer having an aromatic vinyl monomer block content of less than 10% by mass; and a hydrogenation step of adding hydrogen to the conjugated diene polymer, wherein the hydrogenation step is a continuous process, and the number N of perfect mixing vessel rows is 1.0 to 2.5 when a residence time distribution in a reactor is fitted to a perfect mixing vessel row model by an impulse response method.

8. The method for producing a hydrogenated conjugated diene polymer according to claim 7, wherein hydrogen and the conjugated diene polymer are supplied to a reactor in the hydrogenation step from opposite directions, or hydrogen and / or the conjugated diene polymer are each supplied from a plurality of locations.

9. The method for producing a hydrogenated conjugated diene polymer according to claim 7, wherein the continuous process uses a stirred tank reactor, supplies the conjugated diene polymer and a hydrogenation catalyst from an upper part of the stirred tank reactor, stirs the mixture while supplying hydrogen from a bottom part of the stirred tank reactor, and extrudes the hydrogenated conjugated diene polymer from the bottom part of the stirred tank reactor.

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