Rubber compositions and vulcanized rubber compositions

Abstract

The rubber composition of the present invention comprises, relative to 100 parts by mass of a rubber component containing at least one conjugated diene polymer, 10 to 150 parts by mass of carbon black, and the content of silicon dioxide inorganic filler relative to the total amount of filler is 0% to 30% by mass, and at least 10% by mass of the aforementioned rubber component is a modified conjugated diene polymer, wherein the aforementioned modified conjugated diene polymer (1) has a main chain branching structure having a branched structure in the main chain, and (2) the main chain branching structure includes a structure derived from at least one conjugated diene monomer, or derived from at least one The structure of the conjugated diene monomer and the structure derived from the aromatic ethylene monomer, (3) at at least one end, having a terminal group having at least one carbonyl group and at least one substituted amino group in the molecule, (4) the Munich viscosity measured at 100°C is 30 to 120, (5) the branching degree (Bn) obtained by GPC-light scattering method with viscosity detector is 1.1 or higher and less than 4.0, (6) the shape of the chromatogram measured by gel permeation chromatography (GPC) is unimodal and the molecular weight distribution is 1.60 to 3.00, (7) the hydrogenation rate is less than 10 moles.

Description

[Technical Field]

[0001] This invention relates to a composition of a modified conjugated diene polymer, and more specifically, to a rubber composition comprising a modified conjugated diene polymer and a vulcanized rubber composition. [Previous Technology]

[0002] Since then, the demand for lower fuel consumption rates in automobiles has been increasing, and there has been a search for improvements in the rubber materials used in automobile tires, especially the tire treads that come into contact with the road surface.

[0003] In particular, there is a need for tires with improved performance characteristics for high-load tires used in large vehicles such as trucks or buses. These performance characteristics, in addition to the previously recognized high strength or wear resistance for supporting high loads, include fuel efficiency with low energy loss. Specifically, regarding the rubber material for the tread of high-load tires, there is a need for rubber compositions with high tensile strength and excellent fuel efficiency.

[0004] As a rubber material that meets the requirements described above, for example, there are modified conjugated diene polymers having hydroxyl groups at the ends of polymer chains and their compositions, or methods and compositions for manufacturing conjugated diene polymers by reacting a hydroxyl silane compound with the ends of the polymer chains and then further reacting a specific compound such as a hydroxyl silane compound (see, for example, Patent Documents 1 and 2).

[0005] However, for heavy-duty tires, from the point of view of durability and wear resistance, it is still appropriate to use rubber compositions containing carbon black. While seeking rubber compositions that improve fuel efficiency, wear resistance and tensile strength by using carbon black as a filler, there is the following problem: if the filler is not sufficiently dispersed in the rubber composition, it is not possible to fully exhibit fuel efficiency, wear resistance and tensile strength.

[0006] On the other hand, from the viewpoint of durability and processability, rubber products used in industrial applications are suitable for use with rubber compositions formulated with carbon black. For example, as vibration damping rubber for automobiles or trains, rubber materials containing natural rubber with excellent vibration damping properties such as compression set or dynamic amplification are proposed (see, for example, Patent Document 3). [Prior Art Documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2017-171806 [Patent Document 2] International Publication No. 03 / 046020 [Patent Document 3] Japanese Patent Application Publication No. 2004-292679 [Summary of the Invention]

[0008] [Problem to be solved by the invention] However, in recent years, rubber materials have insufficient vibration damping properties, especially in rubber compositions containing carbon black, which have the following problem: if the filler is not sufficiently dispersed, the vibration damping properties cannot be fully exhibited.

[0009] In addition, modified conjugated diene polymers suitable for high-load tire treads and industrial products have the following problems: the packaging (bale) in the shape of the product is prone to flow (hereinafter referred to as "cold flow"), making it difficult to handle the package after storage.

[0010] Based on this background, it is desirable to provide a rubber composition with excellent processability when the rubber composition is prepared with carbon black, excellent fuel efficiency after the rubber composition is vulcanized, excellent tensile strength, abrasion resistance and vibration damping properties. However, there is a problem that the processability of the rubber composition and the tensile strength and abrasion resistance after vulcanization are contradictory and difficult to achieve simultaneously.

[0011] Therefore, in this invention intended to solve the above-mentioned problems, the object is to provide a rubber composition and a vulcanized rubber composition that contain carbon black, a modified conjugated diene polymer with suppressed cold flow, and a rubber composition exhibiting excellent processability and a high degree of balance between fuel efficiency, tensile strength, abrasion resistance, and vibration damping properties after vulcanization. [Technical Means for Solving the Problem]

[0012] The inventors have conducted diligent research and exploration in order to solve the problems of the prior art described above, and as a result, they have discovered that: by using a rubber composition containing 10 to 150 parts by mass of carbon black relative to 100 parts by mass of a rubber component comprising at least one conjugated diene polymer, and by using a specific or modified conjugated diene polymer relative to 0% to 30% by mass of a silica-based inorganic filler relative to the total amount of filler, and by using a specific or modified conjugated diene polymer at 10% or more of the rubber component, the rubber composition exhibits excellent processability, and the resulting vulcanized product exhibits excellent fuel efficiency, tensile strength, abrasion resistance, and vibration damping properties; thus, the present invention is completed.

[0013] That is, the present invention is as follows. <1> A rubber composition, which, relative to 100 parts by mass of a rubber component comprising at least one conjugated diene polymer, comprises 10 to 150 parts by mass of carbon black, and the content of a silicon dioxide inorganic filler is 0% to 30% by mass relative to the total amount of filler, and 10% or more of the rubber component is a modified conjugated diene polymer, wherein the modified conjugated diene polymer (1) has a main chain branch structure having a branch structure in the main chain, (2) the main chain branch structure comprises a structure derived from at least one conjugated diene monomer, or a structure derived from at least one conjugated diene monomer and a structure derived from an aromatic vinyl monomer, (3) has at least one end a terminal group having at least one carbonyl group and at least one substituted amino group in the molecule, and (4) has a Munich viscosity of 30 to 120 measured at 100°C. (5) The branching degree (Bn) obtained by GPC-light scattering method with viscosity detector is 1.1 or more and less than 4.0; (6) The shape of the chromatogram measured by gel permeation chromatography (GPC) is unimodal and the molecular weight distribution is 1.60 to 3.00; (7) The hydrogenation rate is less than 10 mol%. <2> The rubber composition described in <1> above, wherein the amount of 1,2-vinyl bonds in the conjugated diene unit of the modified conjugated diene polymer is 10 mol% or more and 25 mol% or less. <3> The rubber composition described in <1> or <2> above, wherein the amount of aromatic vinyl bonds in the modified conjugated diene polymer is 0% by mass or more and 10% by mass or less. <4> The rubber composition described in any one of <1> to <3> above, wherein the glass transition temperature (Tg) of the modified conjugated diene polymer is -110°C to -80°C. <5> The rubber composition described in any one of <1> to <4> above, wherein the modification rate of the modified conjugated diene polymer, as determined by column adsorption GPC, is 40% by mass or more. <6> The rubber composition described in any one of <1> to <5> above, wherein the hydrogenation rate of the modified conjugated diene polymer is less than 5 moles. <7> The rubber composition described in any one of <1> to <6> above, wherein the modified conjugated diene polymer has the structure shown in the following formula (1) and / or the following formula (2). [Chemical 1] (In formula (1), P represents a conjugated diene polymer containing at least one conjugated diene monomer, and Ra and Rb each independently represent a hydrocarbon group having 1 to 20 carbon atoms). [Chemical 2] (In formula (2), P represents a conjugated diene polymer containing at least one conjugated diene monomer, and Ra and Rb each independently represent a hydrocarbon group having 1 to 20 carbon atoms).<8> The rubber composition described in any one of <1> to <7> above, wherein the main chain branching structure of the modified conjugated diene polymer has a portion derived from an ethylene monomer comprising alkoxysilyl or halosilyl, and the portion derived from the ethylene monomer comprising alkoxysilyl or halosilyl has the aforementioned branching structure. <9> The rubber composition described in <8> above, wherein the portion derived from the ethylene monomer comprising alkoxysilyl or halosilyl is a monomer unit derived from a compound represented by formula (3) or formula (4) below, and the branching structure in the main chain branching structure of the modified conjugated diene polymer has branch points of polymer chains obtained from monomer units derived from compounds represented by formula (3) or formula (4) below. [Chemical 3] (In the formula, R1 represents a hydrogen atom, or an alkyl group with 1 to 20 carbon atoms or an aryl group with 6 to 20 carbon atoms that may have a branched structure in part; R2 to R3 each independently represent an alkyl group with 1 to 20 carbon atoms or an aryl group with 6 to 20 carbon atoms that may have a branched structure in part; when there are multiple R1 to R3, each R1 to R3 is independent; X1 represents an independent halogen atom; m represents an integer from 0 to 2; n represents an integer from 0 to 3; l represents an integer from 0 to 3; (m + n + l) is 3). [Chemical Formula 4] (In the formula, R2 to R5 each independently represent a portion of an alkyl group with 1 to 20 carbon atoms or an aryl group with 6 to 20 carbon atoms that may have a branched structure. When there are multiple R2 to R5, each is independent. X2 to X3 represent independent halogen atoms. m represents an integer from 0 to 2, n represents an integer from 0 to 3, l represents an integer from 0 to 3, (m + n + l) is 3, a represents an integer from 0 to 2, b represents an integer from 0 to 3, c represents an integer from 0 to 3, (a + b + c) is 3). <10> The rubber composition described in <9> above, wherein the main chain branched structure of the modified conjugated diene polymer has monomer units derived from the compound represented by the above formula (3), in the above formula (3), R1 represents a hydrogen atom, and m represents 0. <11> The rubber composition described in <8> or <10> above, wherein the main chain branching structure of the modified conjugated diene polymer has monomer units derived from the compound represented by formula (4) above, where m represents 0 and b represents 0. <12> The rubber composition described in any one of <9> to <11> above, wherein the main chain branching structure of the modified conjugated diene polymer has monomer units derived from the compound represented by formula (3) above, where R1 represents a hydrogen atom, m represents 0, n represents 3, and l represents 0. <13> The rubber composition described in <9> above, wherein the main chain branching structure of the modified conjugated diene polymer has monomer units derived from the compound represented by formula (4) above, where m represents 0, n represents 3, l represents 0, a represents 0, b represents 0, and c represents 3.<14> A vulcanized rubber composition obtained by vulcanizing a rubber composition as described in any one of <1> to <13> above. [Effects of the invention].

[0014] According to the present invention, a rubber composition and a vulcanized rubber composition can be provided that use carbon black, a modified conjugated diene polymer with suppressed cold flow, and a rubber composition with excellent processability and a high degree of consideration for fuel efficiency, tensile strength, abrasion resistance and vibration damping properties after vulcanization.

Implementation Method

[0015] Hereinafter, the method for implementing the present invention (hereinafter referred to as "this embodiment") will be described in detail, but the present invention is not limited thereto, and various changes can be made without departing from its spirit. Furthermore, throughout this specification, expressions connecting numerical values ​​with "~", such as x~y (x and y are each numerical values), mean a range of values ​​including x and y as upper or lower limits.

[0016] <<Rubber Composition>> The rubber composition of this embodiment contains 10 to 150 parts by mass of carbon black relative to 100 parts by mass of the rubber component containing at least one conjugated diene polymer, and the content of silicon dioxide inorganic filler is 0% to 30% by mass relative to the total amount of filler. At least 10% by mass of the rubber component is a modified conjugated diene polymer, which (1) has a main chain branching structure having a branched structure in the main chain, (2) the main chain branching structure includes a structure derived from at least one conjugated diene monomer, or a structure derived from at least one conjugated diene monomer and a structure derived from an aromatic vinyl monomer, (3) has at least one end a terminal group having at least one carbonyl group and at least one substituted amino group in the molecule, and (4) has a Munich viscosity of 30 to 120 measured at 100°C. (5) The branching degree (Bn) obtained by GPC-light scattering method with viscosity detector is greater than 1.1 and less than 4.0; (6) The shape of the chromatogram measured by gel permeation chromatography (GPC) is unimodal and the molecular weight distribution is 1.60 to 3.00; (7) The hydrogenation rate is less than 10 mol%. Modified conjugated diene polymers will be described below.

[0017] [Rubber polymers other than modified conjugated diene polymers in this embodiment] As described above, the rubber composition of this embodiment contains a rubber component comprising at least one conjugated diene polymer and carbon black. The rubber composition of this embodiment may be used as a rubber component by combining rubber-like polymers (hereinafter, sometimes simply referred to as "rubber-like polymers") other than the modified conjugated diene polymers described below.

[0018] There is no particular limitation on this type of rubber-like polymer. Examples include: conjugated diene polymers or their hydrides, random copolymers of conjugated diene compounds and vinyl aromatic compounds or their hydrides, block copolymers of conjugated diene compounds and vinyl aromatic compounds or their hydrides, non-diene polymers, and natural rubber.

[0019] The specific type of conjugated diene polymer is not particularly limited. Examples include: butadiene rubber or its hydrogenated form, isoprene rubber or its hydrogenated form, styrene-butadiene rubber or its hydrogenated form, styrene-butadiene block copolymer or its hydrogenated form, styrene-isoprene block copolymer or its hydrogenated form, and other styrene-based elastomers, as well as acrylonitrile-butadiene rubber or its hydrogenated form.

[0020] As a non-diene polymer, there is no particular limitation. Examples include: olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber; butyl rubber; brominated butyl rubber; acrylic rubber; fluororubber; silicone rubber; chlorinated polyethylene rubber; epichlorohydrin rubber; α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber; ethyl carbamate rubber; and polysulfide rubber.

[0021] As for natural rubber, there are no particular limitations. Examples include: RSS3-5, SMR, and epoxidized natural rubber as smoked sheets.

[0022] The above-mentioned various rubber-like polymers may also be modified rubbers endowed with polar functional groups such as hydroxyl groups and amine groups. When used for tire applications, butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber are preferred.

[0023] From the viewpoint of balancing performance and processing characteristics, the weight-average molecular weight of the rubber-like polymer is preferably 2,000 to 2,000,000, and more preferably 5,000 to 1,500,000. Furthermore, low molecular weight rubber-like polymers, also known as liquid rubbers, can also be used as rubber-like polymers. One type of such rubber-like polymer can be used alone, or two or more can be used in combination.

[0024] In this embodiment, when a rubber composition comprising the modified conjugated diene polymer and a rubber-like polymer is prepared, the content ratio (mass ratio) of the modified conjugated diene polymer to the rubber-like polymer (modified conjugated diene polymer / rubber-like polymer) is preferably 10 / 90 or more and 100 / less, more preferably 20 / 80 or more and 90 / 10 or less, and even more preferably 40 / 60 or more and 80 / 20 or less. Therefore, the total amount (100 parts by mass) of the modified conjugated diene polymer contained in the rubber component relative to the total amount of the rubber component is preferably 10 parts by mass or more and 100 parts by mass, more preferably 20 parts by mass or more and 90 parts by mass, and even more preferably 40 parts by mass or more and 80 parts by mass or less. If the content ratio of (modified conjugated diene polymer / rubber-like polymer) is within the above range, the vulcanized rubber composition will have excellent wear resistance, tensile strength, a good balance between fuel efficiency and slip resistance, and excellent vibration damping performance.

[0025] [Filler] (Carbon Black) The carbon black included in the rubber composition of this embodiment is not particularly limited, and examples include carbon black of various grades such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon black with a nitrogen adsorption specific surface area of ​​50 m2 / g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100g or less is preferred.

[0026] In the rubber composition of this embodiment, the content of carbon black relative to 100 parts by mass of rubber component is preferably 10 parts by mass or more and 150 parts by mass or less, more preferably 25 parts by mass or more and 125 parts by mass or less, and even more preferably 30 parts by mass or more and 100 parts by mass or less.

[0027] In the crosslinked rubber composition of this embodiment, from the viewpoint of exhibiting the performance required for industrial use such as hardness or vibration damping properties, the carbon black content is preferably set to 10 parts by mass or more relative to 100 parts by mass of rubber component, and from the viewpoint of dispersibility, it is preferably set to 150 parts by mass or less relative to 100 parts by mass of rubber component.

[0028] (Fillers other than carbon black) The rubber composition of this embodiment may also contain fillers other than carbon black. There are no particular limitations on fillers other than carbon black; examples include: silicon dioxide-based inorganic fillers, metal oxides, and metal hydroxides. Among these, silicon dioxide is preferred. One type of filler may be used alone, or two or more may be used in combination.

[0029] As a silicon dioxide-based inorganic filler, there are no particular limitations, and known materials can be used. Preferably, it is a solid particle containing SiO2 or Si3Al as a structural unit, and more preferably, it is a solid particle containing SiO2 or Si3Al as the main structural unit. Here, the main component refers to a component that contains 50% or more by mass, more preferably 70% or more by mass, and more preferably 80% or more by mass in the silicon dioxide-based inorganic filler.

[0030] The specific silica-based inorganic filler is not particularly limited, and examples include: silica, clay, talc, mica, diatomaceous earth, silash, montmorillonite, zeolite, glass fiber, and other inorganic fibrous materials. Also examples include: silica-based inorganic fillers with hydrophobic surfaces, and mixtures of silica-based inorganic fillers and inorganic fillers other than silica-based fillers. Of these, silica and glass fiber are preferred from the viewpoint of strength and wear resistance, with silica being more preferred. Examples of silica include: dry silica, wet silica, and synthetic silicate silica. Of these silicas, wet silica is preferred.

[0031] From the viewpoint of obtaining practically good abrasion resistance and breaking strength of the vulcanized rubber composition, the nitrogen adsorption specific surface area of ​​the silica-based inorganic filler, determined by the BET adsorption method, is preferably 100 m² / g or more and 300 m² / g or less, more preferably 170 m² / g or more and 250 m² / g or less. Furthermore, silica-based inorganic fillers with relatively small specific surface areas (e.g., specific surface area of ​​200 m² / g or less) can be used in combination with silica-based inorganic fillers with relatively large specific surface areas (e.g., 200 m² / g or more), as needed.

[0032] The content of the silica-based inorganic filler in the rubber composition is 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, relative to the total amount of filler. When the rubber composition contains a silica-based inorganic filler, its lower limit content relative to the total amount of filler may be set to 15% by mass or more, 10% by mass or more, or 5% by mass or more.

[0033] In the rubber composition of this embodiment, metal oxide refers to solid particles whose main structural unit is a component with the chemical formula MxOy (M represents a metal atom, and x and y each independently represent integers from 1 to 6). There are no particular limitations on the metal oxide; examples include aluminum oxide, titanium oxide, magnesium oxide, and zinc oxide. There are also no particular limitations on the metal hydroxide; examples include aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0034] [Modified Conjugated Diene Polymer] The rubber composition of this embodiment comprises a modified conjugated diene polymer that satisfies the following (1) to (7). (1) It has a main chain branching structure with a branching structure in the main chain, (2) The main chain branching structure includes a structure derived from at least one conjugated diene monomer, or a structure derived from at least one conjugated diene monomer and a structure derived from an aromatic vinyl monomer, (3) It has a terminal group at at least one end, which has at least one carbonyl group and at least one substituted amino group in the molecule, (4) The Munich viscosity measured at 100°C is 30 to 120, (5) The branching degree (Bn) obtained by GPC-light scattering method with a viscosity detector is 1.1 or more and less than 4.0, (6) The shape of the chromatogram measured by gel permeation chromatography (GPC) is unimodal and the molecular weight distribution is 1.60 to 3.00, (7) The hydrogenation rate is less than 10 moles.

[0035] Although there are no particular limitations, the modified conjugated diene polymer in this embodiment can be synthesized by adding a branching agent while polymerizing at least one modified conjugated diene monomer or copolymerizing a conjugated diene monomer with an aromatic vinyl monomer.

[0036] (Method for manufacturing modified conjugated diene polymer) The method for manufacturing modified conjugated diene polymer in this embodiment may include the following steps: a polymerization and branching step, in which a conjugated diene monomer is polymerized using an organolithium compound as a polymerization initiator, and a branching agent is added to obtain a conjugated diene polymer with a main chain branching structure; and a modification step, in which the conjugated diene polymer is modified by a modifier.

[0037] (Polymerization and Branching Process) The polymerization and branching process (hereinafter also referred to as the "polymerization and branching process") in the method for manufacturing modified conjugated diene polymers is as follows: for example, using an organolithium compound as a polymerization initiator, polymerizing at least one conjugated diene compound, and adding a branching agent, thereby obtaining a conjugated diene polymer having a branched structure in the main chain. Hereinafter, when describing the polymerization reaction in the polymerization and branching process, it will also be referred to as the "polymerization process," and when describing the reaction with the branching agent, it will also be referred to as the "branching process."

[0038] In the polymerization process, it is preferable to carry out polymerization via a growth reaction of living anionic polymerization, thereby obtaining a conjugated diene polymer with active ends. Subsequently, in the branching process using a branching agent, the branching of the main chain can also be appropriately controlled, thereby tending to obtain a conjugated diene polymer with a high degree of modification.

[0039] Conjugated diene polymers can also be homopolymers obtained by using a single conjugated diene compound as a monomer, or polymers obtained by using different types of conjugated diene compounds as monomers, i.e., copolymers.

[0040] (Conjugated diene monomers) Specific examples of conjugated diene monomers in this embodiment are not particularly limited, but examples include: 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred from the viewpoint of ease of industrial acquisition. One of these may be used alone, or two or more may be used in combination.

[0041] (Aromatic vinyl monomers) Examples of aromatic vinyl monomers in this embodiment include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-, p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and stilbene, but are not limited to these. Of these, styrene is preferred from the viewpoint of ease of industrial acquisition. One of these monomers may be used alone, or two or more may be used in combination.

[0042] (Polymerization Initiator) As the polymerization initiator in this embodiment, at least an organic monolithium compound can be used. There are no particular limitations on the organic monolithium compound; examples include low-molecular-weight compounds and organic monolithium compounds that are soluble oligomers. Furthermore, regarding the bonding pattern between the organic group and the lithium, examples of organic monolithium compounds include compounds with carbon-lithium bonds, compounds with nitrogen-lithium bonds, and compounds with tin-lithium bonds. The amount of the organic monolithium compound used as the polymerization initiator is preferably determined by the molecular weight of the target conjugated diene polymer.

[0043] The amount of monomers such as conjugated diene compounds used relative to the amount of polymerization initiator is related to the degree of polymerization. That is, there is a tendency to be related to the number average molecular weight and / or weight average molecular weight. Therefore, in order to increase the molecular weight, the amount of polymerization initiator used can be adjusted in the direction of decreasing the amount of polymerization initiator used, and in order to decrease the molecular weight, the amount of polymerization initiator used can be adjusted in the direction of increasing the amount of polymerization initiator used.

[0044] From the viewpoint of being usable in a method of introducing nitrogen atoms into a conjugated diene polymer, the organic monolithium compound is preferably an alkyllithium compound having a substituted amine group, or a dialkylaminolithium. In this case, a conjugated diene polymer having a nitrogen atom at the polymerization initiation end is obtained. The substituted amine group refers to an amine group with a structure that does not contain active hydrogen or has active hydrogen protected.

[0045] There is no particular limitation as to the alkyl lithium compound having an amine group that does not contain active hydrogen, for example: 3-dimethylaminopropyl lithium, 3-diethylaminopropyl lithium, 4-(methylpropylamino)butyl lithium, and 4-hexamethyleneiminobutyl lithium.

[0046] There is no particular limitation on the alkyl lithium compound having an amino group with a structure in which active hydrogen is protected. Examples include 3-bis(trimethylsilyl)aminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0047] There is no particular limitation on the dialkylamino lithium, and examples include: lithium dimethylamino, lithium diethylamino, lithium dipropylamino, lithium dibutylamino, lithium dihexylamino, lithium diheptylamino, lithium diisopropylamino, lithium dioctylamino, lithium di-2-ethylhexylamino, lithium didecylamino. Lithium ethylpropyl acetamiprid, lithium ethylbutyl acetamiprid, lithium ethylbenzyl acetamiprid, lithium methylphenylethyl acetamiprid, lithium hexamethylene acetamiprid, lithium pyrrolidine, lithium piperidinium, lithium heptamethylene acetamiprid, lithium morpholine, 1-lithium-azacyclooctane, 6-lithium-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithium-1,2,3,6-tetrahydropyridine.

[0048] These organolithium compounds with substituted amine groups can also be used as organolithium compounds that produce soluble oligomers by reacting small amounts of polymerizable monomers, such as 1,3-butadiene, isoprene, styrene, etc.

[0049] From the viewpoint of ease of industrial acquisition and ease of controlling the polymerization reaction, alkyl lithium compounds are preferred as organolithium compounds. In this case, a conjugated diene polymer having an alkyl group at the polymerization initiation end is obtained.

[0050] There is no particular limitation on the alkyl lithium compound, but examples include: n-butyllithium, dibutyllithium, tributyllithium, n-hexyllithium, benzyllithium, phenyllithium, and 1,2-stilbenelithium. From the viewpoint of ease of industrial acquisition and ease of controlling the polymerization reaction, n-butyllithium and dibutyllithium are preferred as alkyl lithium compounds. These organolithium compounds can be used alone or in combination of two or more. Furthermore, they can also be used in combination with other organometallic compounds.

[0051] Other organometallic compounds include, for example, alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds.

[0052] As an alkaline earth metal compound, there is no particular limitation. Examples include organomagnesium compounds, organocalcalcium compounds, and organostrontium compounds. Also, examples include alkoxides, sulfonates, carbonates, and acetamine compounds of alkaline earth metals.

[0053] Examples of organomagnesium compounds include, for example, dibutylmagnesium and ethylbutylmagnesium. Examples of other organometallic compounds include, for example, organoaluminum compounds.

[0054] (Polymerization method) In the polymerization process of this embodiment, there is no particular limitation on the polymerization reaction pattern. For example, batch polymerization (also known as "batch type") and continuous polymerization reaction patterns can be cited.

[0055] In a continuous reactor, one or more connected reactors may be used. Continuous reactors may be, for example, tank-type or tubular type reactors equipped with a stirrer. Preferably, in a continuous reactor, monomers, inert solvents, and polymerization initiators are continuously supplied to the reactor to obtain a polymer solution containing the polymer, and the polymer solution is continuously discharged.

[0056] Batch reactors, for example, use tank-type reactors with a stirrer. In a batch reactor, it is preferable to supply monomers, inert solvents, and polymerization initiators, and to continuously or intermittently add monomers during polymerization as needed, to obtain a polymer solution containing the polymer in the reactor, and to discharge the polymer solution after polymerization is completed.

[0057] (Polymerization Solvent) In this embodiment, the polymerization process of the conjugated diene polymer is preferably carried out in an inert solvent. The solvent is not particularly limited; examples include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents are not particularly limited; examples include aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; and hydrocarbons composed of mixtures thereof.

[0058] By treating the impurities such as propadiene and acetylene with organometallic compounds before the polymerization reaction, there is a tendency to obtain conjugated diene polymers with high concentrations of active terminals, and there is a tendency to obtain modified conjugated diene polymers with higher modification rates, which is therefore better.

[0059] (Polar compound) A polar compound may also be added during the polymerization process. It tends to be an ethyleneizing agent that can also be used to control the amount of 1,2-vinyl bonds in conjugated diene polymers. Furthermore, it tends to have an effect on promoting the polymerization reaction.

[0060] As a polar compound, there are no particular limitations. For example, the following ethers can be used: tetrahydrofuran, diethyl ether, dialkyl, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, 2,2-bis(2-tetrahydrofuranyl)propane, etc.; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinyl ethane, trimethylamine, triethylamine, pyridine, pyridine, etc.; alkali metal alkoxide compounds such as potassium terpentoxide, potassium terbutoxide, sodium terbutoxide, sodium pentanoxide, etc.; and phosphine compounds such as triphenylphosphine, etc.

[0061] One of these polar compounds may be used alone, or two or more may be used in combination. There is no particular limitation on the amount of polar compound used, and it may be selected according to the purpose, etc. It is preferred to be 0.01 mol to 100 mol relative to 1 mol of polymerization initiator.

[0062] This polar compound (ethyleneizing agent) can be used as a regulator of the microstructure of conjugated diene polymers, and should be used in appropriate amounts according to the required amount of 1,2-vinyl bonds.

[0063] (Polymerization Temperature) The polymerization temperature in the polymerization process is preferably the temperature at which the active anionic polymerization takes place. From a production point of view, it is more preferably above 0°C, and even more preferably below 120°C. Within this range, there is a tendency to sufficiently ensure the amount of modifier reacting with the active end after polymerization. More preferably, it is between 50°C and 100°C.

[0064] (Branching Process) The rubber composition of this embodiment includes a modified conjugated diene polymer, which (1) has a main chain branching structure with branched structures in the main chain, and (2) the main chain branching structure is derived from the structure of at least one conjugated diene monomer, or from the structure of at least one conjugated diene monomer and the structure of an aromatic vinyl monomer. The modified conjugated diene polymer is obtained by adding a branching agent while polymerizing at least one conjugated diene monomer or copolymerizing a conjugated diene monomer with an aromatic vinyl monomer.

[0065] The amount of branching agent added in the branching process that forms the branch structure is not particularly limited and can be selected according to the purpose, etc. It is more preferably 0.02 mol or more and 0.5 mol or less relative to 1 mol of polymerization initiator, more preferably 0.03 mol or more and 0.4 mol or less, and even more preferably 0.03 mol or more and 0.3 mol or less.

[0066] The branching agent may be used in appropriate amounts according to the number of branching points required for the branching structure of the conjugated diene portion of the conjugated diene polymer.

[0067] In the branching process, there is no particular limitation on the timing of adding the branching agent, which can be selected according to the purpose, etc. From the viewpoint of increasing the absolute molecular weight of the conjugated diene polymer and increasing the modification rate, it is preferable to add the raw material conversion rate of 20% or more after the polymerization initiator is added, more preferably to add the raw material conversion rate of 40% or more, further preferably to add the raw material conversion rate of 50% or more, further preferably to add the raw material conversion rate of 65% or more, and even more preferably to add the raw material conversion rate of 75% or more.

[0068] Furthermore, after adding the branching agent, the required raw materials can be added, and the polymerization process can be carried out after branching, and the above-described contents can be repeated.

[0069] The modified conjugated diene polymer in this embodiment is not particularly limited and can be a polymer of a conjugated diene monomer and a branching agent, or a copolymer of a conjugated diene monomer, a branching agent, and other monomers. For example, when the conjugated diene monomer is butadiene or isoprene, and it is polymerized with a branching agent containing a vinyl aromatic portion (i.e., an aromatic vinyl monomer), it becomes a polymer with a polymer chain of so-called polybutadiene or polyisoprene and the branched portion contains a structure derived from the vinyl aromatic group. By having this structure, the linearity of each polymer chain is improved, the crosslinking density after vulcanization is increased, and the effect of improved wear resistance is achieved. Therefore, the conjugated diene polymer of this embodiment is more suitable for applications such as tires, resin modification, automotive interior and exterior parts, vibration damping rubber, and footwear.

[0070] When the rubber composition of this embodiment is used for the tread of a high-load tire, a copolymer of a conjugated diene monomer and a branching agent is more suitable as a modified conjugated diene polymer.

[0071] (Modified Conjugated Diene Polymer) The modified conjugated diene polymer (3) in this embodiment has a terminal group at at least one end, which has at least one carbonyl group and at least one substituted amino group in the molecule. The modified conjugated diene polymer in this embodiment is, for example, a modified conjugated diene polymer that is obtained by modifying the molecule having at least one carbonyl group (>C=O group) and at least one substituted amino group in the molecule by reacting with the active end of the conjugated diene polymer. That is, the terminal group having at least one carbonyl group and at least one substituted amino group in the molecule of the modified conjugated diene polymer in this embodiment is formed by modifying the active end by the above-mentioned modifier, and it is a group derived from the structure of the modifier.

[0072] In the above-mentioned modifier, the carbonyl group and the substituted amino group can be adjacent or separated. Examples of compounds with adjacent functional groups include amides, amides, ureas, and isocyanurates having a "-C(=O)-N<" bond. Among these, cyclic compounds are preferred, more preferably N-substituted cyclic amides and N-substituted cyclic ureas, and especially N-substituted cyclic ureas. Furthermore, examples of compounds with separated carbonyl groups and substituted amino groups include N-substituted amino ketones and N-substituted amino aldehydes, with N-substituted amino ketones being more preferred.

[0073] In this embodiment, two or more modifiers may be used, and the method of adding the modifiers in the modification process may be carried out simultaneously or separately. When two or more modifiers are used, the modified conjugated diene polymer in this embodiment becomes a conjugated diene polymer with two or more terminal groups modified.

[0074] There is no particular limitation on the amount of modifier used, and it can be selected according to the purpose, etc. It is more preferably 0.10 mol or more and 3.00 mol or less relative to 1 mol of polymerization initiator, more preferably 0.30 mol or more and 2.00 mol or less, and even more preferably 0.50 mol or more and 1.50 mol or less.

[0075] As a modifier having at least one carbonyl group and at least one substituted amino group in the molecule of this embodiment, there is no particular limitation. Examples of N-substituted cyclic amides include: N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, N-methyl-2-piperidone, N-phenyl-2-piperidone, N-methyl-ε-caprolactone, N-phenyl-ε-caprolactone, etc.

[0076] As an N-substituted cyclic urea, there are no particular limitations. Examples include: 1,3-dimethylvinylurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, etc.

[0077] As an N-substituted amino ketone, there are no particular limitations. Examples include 4,4'-bis(dimethylamino)benzophenone and 4,4'-bis(diethylamino)benzophenone.

[0078] As an N-substituted amino aldehyde, there are no particular limitations. Examples include 4-N,N-dimethylaminobenzaldehyde, etc.

[0079] [Structure of the terminal group of the modified conjugated diene polymer] In the modified conjugated diene polymer of this embodiment, the terminal group having at least one carbonyl group and at least one substituted amino group in the molecule is preferably having the structure (amino group or amide group) shown in the following formula (1) and / or the following formula (2).

[0080] [Chemical 5] (In formula (1), P represents a conjugated diene polymer containing at least one conjugated diene monomer, and Ra and Rb each independently represent a hydrocarbon group with 1 to 20 carbon atoms).

[0081] [Chemical 6] (In formula (2), P represents a conjugated diene polymer containing at least one conjugated diene monomer, and Ra and Rb each independently represent a hydrocarbon group with 1 to 20 carbon atoms).

[0082] Because the modified conjugated diene polymer in this embodiment has the terminal groups as described above, after preparing a rubber composition, especially containing carbon black as a filler, the terminal groups interact or bond with the functional groups on the surface of carbon black, tending to improve the dispersion of carbon black in the rubber composition, and the fuel-saving rate or dynamic scale-up after preparing the sulfurized product is excellent.

[0083] In this embodiment, the modifier used to form the structure shown in formula (1) is not particularly limited, and examples include: 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-imidazolinone, etc.

[0084] In this embodiment, the modifier shown in formula (2) is not particularly limited, and examples include: 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, etc.

[0085] (Modification process) In the method for manufacturing the modified conjugated diene polymer in this embodiment, there may be a modification process (hereinafter also referred to as "modification process") in which the conjugated diene polymer obtained by the above-mentioned polymerization and branching process is modified by the above-mentioned modifier.

[0086] In the modification process, one of the active ends of the conjugated diene polymer is modified by the aforementioned modifier to obtain the conjugated diene polymer. The reaction temperature in the modification process is preferably the same as the polymerization temperature of the conjugated diene polymer, more preferably 0°C to 120°C, and even more preferably 50°C to 100°C. Regarding the reaction time in the modification process, it is preferably set to a reaction time of 10 seconds or more, and even more preferably 30 seconds or more.

[0087] The mixing in the modification process can be any of mechanical stirring or stirring using a static mixer. If the polymerization process is continuous, it is preferable that the modification process is also continuous. The reactor in the modification process may be, for example, a tank-type or tubular type with an attached agitator.

[0088] The modifier can also be continuously supplied to the reactor after being diluted with an inert solvent. In the case of a batch polymerization process, the modifier can be directly added to the polymerization reactor, or it can be transferred to other reactors for the modification process.

[0089] The time from the polymerization step to the modification step is preferably short, preferably within 10 minutes, and more preferably within 5 minutes. In this case, there is a tendency to obtain conjugated diene polymers with higher modification efficiency. The time from the polymerization step to the modification step, for example, in the case of batch polymerization, refers to the time from reaching the peak polymerization temperature to adding the modifier, and in the case of continuous polymerization, it refers to the time from adding the modifier to the solution containing the conjugated diene polymer leaving the polymerization reactor.

[0090] In this embodiment, a condensation reaction step in the presence of a condensation accelerator may be carried out after the modification step.

[0091] Regarding the conjugated diene polymer of this embodiment, the conjugated diene portion in the conjugated diene polymer chain can also be hydrogenated. There are no particular limitations on the method for hydrogenating the conjugated diene portion of the conjugated diene polymer, and known methods can be used. Suitable hydrogenation methods include: hydrogenation by blowing gaseous hydrogen into the polymer solution in the presence of a catalyst. There are no particular limitations on the catalyst; examples include: heterogeneous catalysts such as those obtained by supporting noble metals on porous inorganic materials; homogeneous catalysts such as those obtained by soluble salts of nickel, cobalt, etc., and reacting them with organoaluminum compounds; and metallocene catalysts such as those using titanium thiocyanate. Among these, titanium thiocyanate catalysts are preferred from the viewpoint of selecting mild hydrogenation conditions. Furthermore, the hydrogenation of aromatic groups can be carried out using a noble metal-supported catalyst.

[0092] There are no particular limitations on the hydrogenation catalyst. Examples include: (1) supported heterogeneous hydrogenation catalysts obtained by supporting metals such as Ni, Pt, Pd, and Ru on carbon, silicon dioxide, aluminum oxide, diatomite, etc.; (2) so-called Ziegler-type hydrogenation catalysts using transition metal salts such as organic acid salts of Ni, Co, Fe, and Cr, or acetone salts, and reducing agents such as organoaluminum; and (3) so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, and Zr. Furthermore, there are no particular limitations on the hydrogenation catalyst; for example, known hydrogenation catalysts described in Japanese Patent Publication Nos. 42-8704, 43-6636, 63-4841, 1-37970, 1-53851, 2-9041, and 8-109219 can be cited. As a preferred hydrogenation catalyst, a reaction mixture of a titanocene compound and a reducing organometallic compound can be cited.

[0093] The reaction temperature of the hydrogenation reaction is preferably the same as the polymerization temperature of the conjugated diene polymer, preferably between 0°C and 120°C, and more preferably between 50°C and 100°C. Regarding the reaction time of the hydrogenation reaction, it is preferably set to a reaction time of 10 seconds or more, and more preferably to a reaction time of 30 seconds or more.

[0094] The hydrogenation reaction can be any of the following: mechanical stirring, stirring using a static mixer, etc. When the polymerization process is continuous, it is preferable that the hydrogenation reaction is also continuous. The reactor used in the hydrogenation reaction may be, for example, a tank-type or tubular type with an attached stirrer.

[0095] The hydrogenation catalyst can also be continuously supplied to the reactor after being diluted with an inert solvent. In the case of a batch polymerization process, the hydrogenation reaction can be carried out by directly adding the hydrogenation catalyst to the polymerization reactor and blowing in hydrogen, or it can be transferred to other reactors for hydrogenation reaction.

[0096] In the method for manufacturing conjugated diene polymers of this embodiment, deactivating agents, neutralizing agents, etc. may be added to the polymer solution as needed after the modification process.

[0097] There are no particular limitations on the deactivating agent. Examples include: water; methanol, ethanol, isopropanol, etc.

[0098] As a neutralizing agent, there are no particular limitations. Examples include: carboxylic acids such as stearic acid, oleic acid, and decacarbonate (a mixture of carboxylic acids with 9 to 11 carbon atoms and more branches centered around 10 carbon atoms); aqueous solutions of inorganic acids and carbon dioxide.

[0099] In the method for manufacturing the modified conjugated diene polymer in this embodiment, from the viewpoint of preventing gel formation after polymerization and improving stability during processing, it is preferable to add a rubber stabilizer.

[0100] As a stabilizer for rubber, known stabilizers may be used, such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol) propionate, 2-methyl-4,6-bis[(octylthio)methyl]phenol and other antioxidants, but are not limited to these.

[0101] In order to further improve the productivity of the modified conjugated diene polymer in this embodiment and the processability when preparing a composition containing fillers, etc., a rubber softener may be added as needed.

[0102] There are no particular limitations on the type of rubber softener, and examples include: bulking oil, liquid rubber, resin, etc. There are no particular limitations on the method of adding the rubber softener to the conjugated diene polymer, but a preferred method is to add the rubber softener to a conjugated diene polymer solution, mix to prepare a polymer solution containing the rubber softener, and then desolventize it.

[0103] Preferred additive oils include, for example, aromatic oils, naphthenic oils, paraffin oils, etc. Among these, from the viewpoint of environmental safety, as well as from the viewpoint of oil impermeability and wet grip properties, it is preferable to use an aromatic oil substitute with a polycyclic aromatic (PCA) content of 3% by mass or less according to the IP346 method. Examples of aromatic oil substitutes include TDAE (Treated Distillate Aromatic Extracts), MES (Mild Extraction Solvate), and RAE (Residual Aromatic Extracts) as shown in Kautschuk Gummi Kunststoffe 52(12)799(1999).

[0104] There is no particular limitation on the preferred liquid rubber, and examples include liquid polybutadiene, liquid styrene-butadiene rubber, etc. As for the effects of adding liquid rubber, there are tendencies to be: improved processability when preparing compositions containing conjugated diene polymers and fillers, etc. In addition, by being able to shift the glass transition temperature of the composition to the low-temperature side, the wear resistance, low hysteresis loss, and low-temperature characteristics of the vulcanized product are improved.

[0105] There is no particular limitation on the preferred resin, but examples include: aromatic petroleum resins, benzofuran-indene resins, terpene resins, rosin derivatives (including tung oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, oligomers of monoolefins, oligomers of dienes, aromatic hydrocarbon resins, aromatic petroleum resins, hydrogenated aromatic hydrocarbon resins, cyclic aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated tung oil resins, hydrogenated oil resins, hydrogenated oil resins, and esters of monofunctional or polyfunctional alcohols. One of these resins may be used, or two or more may be used in combination. In the case of hydrogenation, all unsaturated groups may be hydrogenated, or some may remain.

[0106] As an effect of adding resin, in addition to improving the processability when making a composition containing conjugated diene polymers and fillers, it also tends to improve the breaking strength after making a sulfurized product. Furthermore, it tends to improve the anti-slip properties by shifting the glass transition temperature of the composition to the high-temperature side.

[0107] The amount of rubber softener, such as bulking oil, liquid rubber, or resin, added is not particularly limited. However, relative to 100 parts by weight of the modified conjugated diene polymer in this embodiment, it is preferably 1 part by weight or more and 60 parts by weight, more preferably 5 parts by weight or more and 50 parts by weight, and even more preferably 10 parts by weight or more and 37.5 parts by weight or less. If the rubber softener is added within the above range, there is a tendency for the processability of the composition formulated with the conjugated diene polymer and fillers to improve, and for the breaking strength and abrasion resistance of the vulcanized product to improve.

[0108] (Desolventization Step) In the method for manufacturing the modified conjugated diene polymer in this embodiment, known methods can be used as the method for obtaining the modified conjugated diene polymer from the polymer solution. There are no particular limitations on this method; examples include: separating the polymer by steam stripping or similar means, filtering the polymer, and then dehydrating and drying it to obtain the polymer; concentrating the polymer in a washing tank and then removing it from the volatilization using a degassing extruder or similar means; and directly removing the volatilization using a rotary dryer or similar means.

[0109] (Munich viscosity) The modified conjugated diene polymer (4) in this embodiment has a Munich viscosity of 30 to 120 measured at 100°C. Specifically, from the viewpoints of the productivity of the conjugated diene polymer, the processability when preparing a composition containing fillers, etc., and the wear resistance and breaking strength of the composition after it is made into a sulfurized product, the modified conjugated diene polymer in this embodiment has a Munich viscosity of 30 or more and 120 or less, preferably 35 or more and 100 or less, and more preferably 40 or more and 90 or less.

[0110] By making the Munich viscosity measured at 100°C 30 or higher, the wear resistance and breaking strength of the sulfurized product are improved. Furthermore, by making the Munich viscosity measured at 100°C 120 or lower, the obstacles to the manufacture of conjugated diene polymers are suppressed, and the processability of the composition formulated with fillers and the like is improved.

[0111] In the determination of Munich viscosity, a sample obtained by pressing a conjugated diene polymer into a plate shape is used and placed in an apparatus. The sample is first preheated at 100°C for 1 minute, and then the rotor is rotated at 2 rpm. The torque after 4 minutes is measured, and the measured value is set as the Munich viscosity (ML(1+4)). More specifically, it can be determined by the method described in the following examples. The Munich viscosity of the conjugated diene polymer can be controlled within the above range by, for example, controlling the temperature conditions in the polymerization process, or adjusting the degree of branching in the branching process.

[0112] (Branching Degree (Bn)) The branching degree (Bn) of the modified conjugated diene polymer (5) in this embodiment, obtained by GPC-light scattering method using an adhesion detector, is 1.1 or higher and less than 4.0. Specifically, from the viewpoints of processability, abrasion resistance, and breaking strength, the modified conjugated diene polymer in this embodiment has a branching degree (Bn) of 1.1 or higher and less than 4.0, obtained by GPC-light scattering method using an adhesion detector.

[0113] The term “branching degree (Bn) not reaching 4.0” means that the branching structure of the modified conjugated diene polymer in this embodiment has less than 4 polymer chains relative to the longest polymer backbone.

[0114] The branching degree (Bn) of conjugated diene polymers is defined as g' = 6Bn / {(Bn+1)(Bn+2)}, which is determined by the shrinkage factor (g') using a GPC-light scattering method with an attached viscosity detector. Generally speaking, branched polymers tend to have smaller molecular sizes when compared with straight-chain polymers of the same absolute molecular weight.

[0115] The shrinkage factor (g') is an indicator of the ratio of the size of a molecule to that of a linear polymer with the same absolute molecular weight. That is, there is a tendency for the shrinkage factor (g') to decrease as the branching degree of the polymer increases.

[0116] In this embodiment, the intrinsic viscosity is used as an indicator of molecular size for the shrinkage factor, and the linear polymer is set according to the formula intrinsic viscosity [η] = 10⁻³.883 × M⁰.771. In the above formula, M is the absolute molecular weight.

[0117] However, the shrinkage factor represents the rate of reduction in molecular size, not the accurate representation of the branching structure of the polymer. Therefore, the branching degree (Bn) of the conjugated diene polymer is calculated using the shrinkage factor (g') value at each absolute molecular weight. The calculated "branching degree (Bn)" accurately represents the number of polymers directly or indirectly bonded to each other relative to the longest main chain structure.

[0118] The calculated branching degree (Bn) becomes an indicator of the branching structure of conjugated diene polymers. For example, in the case of a typical 4-branched star polymer (with 4 polymer chains connected in the central part), the branching degree (Bn) is evaluated as 2 relative to the longest highly branched main chain structure which has 2 polymer chain arms.

[0119] In the case of a typical 6-branched star polymer, the longest highly branched main chain has 4 polymer chain arms, and the branching degree (Bn) is evaluated as 4.

[0120] Ideally, the conjugated diene polymer of this embodiment has a branching degree (Bn) of 1.1 or more and less than 4.0. In this case, it means that the conjugated diene polymer system, as a star polymer structure, has the same branching as a star polymer structure with less than 6 branches in the straight chain.

[0121] Here, "branching" refers to the formation of a polymer by which other polymers are directly or indirectly bonded to each other relative to one polymer. Also, "branching degree (Bn)" refers to the number of polymers that are directly or indirectly bonded to each other relative to the longest main chain structure.

[0122] With a branching degree (Bn) of 1.1 or higher and less than 4.0, the modified conjugated diene polymer in this embodiment tends to suppress cold flow of the package as a product of the conjugated diene copolymer, while the interaction with the filler becomes good, and the fuel consumption rate or dynamic scale-up is excellent after the product is made into a sulfurized product.

[0123] In this embodiment, the branching degree (Bn) of the modified conjugated diene polymer is 1.1 or higher and less than 4.0, preferably 1.2 or higher and less than 3.9, more preferably 1.3 or higher and less than 3.8, and even more preferably 1.4 or higher and less than 3.7. Conjugated diene polymers with a branching degree (Bn) within this range tend to have excellent fuel efficiency or dynamic scaling-up after being made into sulfurized products.

[0124] The branching degree of the modified conjugated diene polymer can be controlled to be above 1.1 and below 4.0 based on the combination of the amount of branching agent added and the amount of end modifier added. Specifically, the branching degree can be controlled based on the functional group of the branching agent, the amount of branching agent added, the time of addition of the branching agent, and the functional group and amount of nitrogen-containing modifier added.

[0125] (Molecular Weight Distribution) The modified conjugated diene polymer (6) in this embodiment exhibits a unimodal chromatogram as measured by gel permeation chromatography (GPC), with a molecular weight distribution of 1.60 to 3.00. Specifically, the modified conjugated diene polymer in this embodiment exhibits a unimodal chromatogram as measured by gel permeation chromatography (GPC). A unimodal chromatogram means that the chromatogram shape measured by the method described in the following examples shows a peak originating from the polymer with a single top and no valleys in the peak shape.

[0126] The control of the GPC chromatography shape of modified conjugated diene polymers can be achieved by, for example, setting the polymerization mode to continuous polymerization and appropriately controlling the type or amount of branching agent in the branching process and the type or amount of end-modifier in the modification process. More specifically, it can be achieved by the methods described in the following examples.

[0127] In this embodiment, the molecular weight distribution (Mw / Mn), expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the modified conjugated diene polymer, is 1.60 or more and 3.00 or less. Conjugated diene polymers with molecular weight distributions within this range tend to exhibit excellent abrasion resistance and breaking strength when formulated into sulfurized products with compositions containing fillers, etc. More preferably, the molecular weight distribution is 1.65 or more and 2.70 or less, and even more preferably, 1.70 or more and 2.50 or less.

[0128] The number average molecular weight, weight average molecular weight, and molecular weight distribution of the modified conjugated diene polymer can be determined by the methods described in the following examples. The number average molecular weight, weight average molecular weight, and molecular weight distribution of the conjugated diene polymer can be controlled within the above range by, for example, controlling the temperature conditions in the polymerization process, or adjusting the degree of branching in the branching process.

[0129] The modified conjugated diene polymer (7) in this embodiment has a hydrogenation rate of less than 10 mol%. The hydrogenation rate in this embodiment refers to the hydrogenation rate of the double bonds in the structural units derived from the conjugated diene compound in the modified conjugated diene polymer. Modified conjugated diene polymers within this hydrogenation rate range tend to have the following characteristics: for example, they exhibit higher phase separability when formulated into compositions with other rubber components such as natural rubber, and they exhibit excellent dispersibility of the filler when formulated into compositions with fillers, as they demonstrate the effect of end-modified groups. From this point of view, a hydrogenation rate of less than 5 mol is preferred, and more preferably less than 3 mol, and even more preferably a non-hydrogenated form.

[0130] The hydrogenation rate of the modified conjugated diene polymer can be determined using a nuclear magnetic resonance apparatus (1H-NMR) and by the method described in the examples below.

[0131] In order to keep the hydrogenation rate within the above-mentioned range, it can be controlled by appropriately controlling the amount of hydrogen added to the double bond in the structural unit derived from the conjugated diene compound, or the amount of hydrogenation catalyst, hydrogen pressure, reaction temperature, reaction time, and other conditions in the hydrogenation reaction. More specifically, it is described in the following examples.

[0132] [1,2-Vinyl Bond Amount] The 1,2-vinyl bond amount of the modified conjugated diene polymer in this embodiment is preferably 25 mol% or less, more preferably 23 mol% or less, further preferably 22 mol% or less, and even more preferably 20 mol% or less. The lower limit of the 1,2-vinyl bond amount is not particularly limited, but is preferably 7 mol% or more, further preferably 10 mol% or more, and even more preferably 12 mol% or more. As an example of a combination of the upper and lower limits of the 1,2-vinyl bond amount, there is no particular limitation, but is preferably 10 mol% or more and 25 mol% or less, preferably 10 mol% or more and 25 mol% or less, and even more preferably 12 mol% or more and 22 mol% or less.

[0133] The microstructure of the modified conjugated diene polymer can be determined using a Fourier transform infrared spectrophotometer and by the methods described in the following examples.

[0134] To keep the amount of 1,2-vinyl bonds within the aforementioned specific range, the amount of polar substance added during the polymerization process can be controlled. If a large amount of polar compound is added, there is a tendency for the following: in addition to a higher amount of 1,2-vinyl bonds, it also promotes the polymerization reaction; on the other hand, the breaking strength and abrasion resistance decrease after the composition containing fillers, etc., is prepared. Therefore, it is necessary to adjust the amount of polar substance added to control the amount of 1,2-vinyl bonds within a specific range. More specifically, this is described in the following examples.

[0135] [Amount of Aromatic Vinyl Bonds] In this embodiment, the amount of aromatic vinyl bonds in the modified conjugated diene polymer is preferably 0% by mass or more and 10% by mass or less. More preferably, the upper limit of the amount of aromatic vinyl bonds in the conjugated diene polymer is 7% by mass or less, more preferably 6% by mass or less, and even more preferably 5% by mass or less.

[0136] The amount of aromatic vinyl bonds can be controlled by adjusting the addition ratio of conjugated diene monomers to aromatic vinyl compounds in the above polymerization process. More specifically, this is described in the following examples.

[0137] The amount of aromatic vinyl bonds in conjugated diene polymers can be determined using an ultraviolet spectrophotometer and by the method described in the examples below.

[0138] By keeping the amount of aromatic vinyl bonds within a specific range, there is a tendency to improve the breaking strength and wear resistance after preparing a composition containing fillers, etc.

[0139] [Glass transition temperature (Tg)] The glass transition temperature of the conjugated diene polymer of this embodiment is preferably in the range of -110°C to -80°C. The lower limit of the glass transition temperature of the conjugated diene polymer is more preferably -105°C or higher, more preferably -103°C or higher, and even more preferably -100°C or higher.

[0140] Furthermore, the upper limit of the glass transfer temperature is preferably below -82°C, more preferably below -84°C, and even more preferably below -86°C.

[0141] The glass transition temperature tends to increase if the amount of 1,2-vinyl bonds and aromatic vinyl bonds increases. This can be controlled by adjusting the amount of 1,2-vinyl bonds and aromatic vinyl bonds within an appropriate range. More specifically, this is described in the following embodiments.

[0142] The glass transition temperature of the conjugated diene polymer can be determined using a differential scanning calorimeter (DSC) and by the method described in the following examples.

[0143] By keeping the glass transfer temperature within a specific range, there is a tendency to improve the breaking strength and wear resistance after preparing a composition containing fillers, etc.

[0144] [Modification Rate] In this embodiment, the modified conjugated diene polymer preferably has a modification rate of 40% by mass or more. The term "modification rate" is sometimes used in this specification; it refers to the mass ratio of the conjugated diene polymer having nitrogen-containing functional groups to the total amount of the conjugated diene polymer. The modification rate can be determined by chromatography, which can separate the modified and unmodified components containing functional groups.

[0145] As a method for using this chromatography method, the following method can be cited: using a gel permeation chromatography column that uses polar substances such as silicon dioxide that adsorb specific functional groups as packing materials, and using internal standards of non-adsorbed components for comparison to perform quantification (column adsorption GPC method).

[0146] More specifically, the modification rate can be obtained by the following method: for a sample solution containing the sample and low molecular weight internal standard polystyrene, the amount of adsorption on the silicon dioxide column is determined based on the difference between the chromatography pattern determined by the polystyrene gel column and the chromatography pattern determined by the silicon dioxide column.

[0147] More specifically, the modification rate can be determined by the method described in the examples.

[0148] In the modified conjugated diene polymer of this embodiment, the modification rate can be controlled by adjusting the amount of modifier added and the reaction method, thereby enabling the modification rate to be controlled at 40% by mass or more.

[0149] [Branching Structure] In this embodiment, the modified conjugated diene polymer preferably has a main chain branching structure having a portion originating from an ethylene monomer containing alkoxysilyl or halosilyl groups, and the aforementioned branching structure is present in the portion originating from the ethylene monomer containing alkoxysilyl or halosilyl groups. Specifically, in this embodiment, the modified conjugated diene polymer preferably has a portion originating from an ethylene monomer containing alkoxysilyl or halosilyl groups in a portion of the polymer chain, and the branching structure is present in the portion originating from the ethylene monomer containing alkoxysilyl or halosilyl groups.

[0150] The branched structure is defined as having one or more branch points, preferably three or more branch points, and more preferably four or more branch points, derived from a portion of an ethylene monomer containing alkoxysilyl or halosilyl groups.

[0151] Furthermore, the branching point forming the branch structure preferably has at least one polymer chain, more preferably has two or more non-main chain polymer chains, and even more preferably has four or more non-main chain polymer chains.

[0152] In particular, in branched structures composed of ethylene monomers containing alkoxysilyl or halosilyl groups, when the signal is detected by 29Si-NMR, peaks originating from the branched structure are detected in the range of -45 ppm to -65 ppm, and more specifically in the range of -50 ppm to -60 ppm.

[0153] In a preferred embodiment of the conjugated diene polymer, a modified conjugated diene polymer is obtained. The ends of the polymer chains of the modified conjugated diene polymer are modified by a modifier containing nitrogen atoms. A portion of the polymer chain has a portion derived from an ethylene monomer containing alkoxysilyl or halosilyl groups, and the portion derived from the ethylene monomer containing alkoxysilyl or halosilyl groups has a further branched structure. Regarding the method for obtaining the modified conjugated diene polymer, it can be formed by adjusting the functional group and the amount of the modifier containing nitrogen atoms. The branched structure can be controlled by adjusting the functional group of the branching agent, the amount of the branching agent, and the timing of the addition of the branching agent. In this specification, "the portion derived from vinyl monomers" refers to the structure in which the alkoxy groups and / or halogens of the vinyl monomers used as branching agents become free radicals and are substituted by polymerically active ends, forming a silicon-bonded polymer chain in vinyl silane, and the vinyl polymerization of vinyl silane forms an aromatic vinyl compound. When an vinyl monomer containing a plurality of alkoxy groups and / or halogens is used as a branching agent, the obtained "the portion derived from vinyl monomers" can form a plurality of silicon-bonded polymer chains in vinyl silane.

[0154] In order to obtain a conjugated diene polymerization in which a portion of the polymer chain is derived from an ethylene monomer containing alkoxysilyl or halosilyl and has a further branched structure in the portion derived from the ethylene monomer containing alkoxysilyl or halosilyl, for example, the following method can be used: polymerizing with an organolithium compound as a polymerization initiator, adding a branching agent that imparts a specific branching point during or after polymerization, and modifying with a modifier that imparts a specific branching rate after continued polymerization.

[0155] [Branching Agent Structure] The modified conjugated diene polymer in this embodiment is a monomer unit derived from the above-mentioned ethylene monomer containing alkoxysilyl or halosilyl groups, which is derived from the monomer unit of the compound represented by formula (3) or (4) below. It is more preferably a polymer chain with branching points obtained from the monomer unit of the compound represented by formula (3) or (4) below. It is even more preferably a conjugated diene polymer obtained by using the branching agent below. Furthermore, it is more preferably a modified conjugated diene polymer in which at least one end of the conjugated diene polymer is modified by a modifier having an amino group and an amino group.

[0156] [Chemical 7] In the formula, R1 represents a hydrogen atom, or an alkyl group with 1 to 20 carbon atoms or an aryl group with 6 to 20 carbon atoms that may have a branched structure in a part thereof; R2 to R3 each independently represent an alkyl group with 1 to 20 carbon atoms or an aryl group with 6 to 20 carbon atoms that may have a branched structure in a part thereof; when there are multiple R1 to R3, each R1 to R3 is independent; X1 represents an independent halogen atom; m represents an integer from 0 to 2; n represents an integer from 0 to 3; l represents an integer from 0 to 3; and (m + n + l) is 3.

[0157] [Chemical 8] In the formula, R2 to R5 each independently represent a portion of an alkyl group with 1 to 20 carbon atoms or an aryl group with 6 to 20 carbon atoms that may have a branched structure. When there are multiple R2 to R5, each is independent. X2 to X3 represent independent halogen atoms. m represents an integer from 0 to 2, n represents an integer from 0 to 3, l represents an integer from 0 to 3, (m + n + l) is 3, a represents an integer from 0 to 2, b represents an integer from 0 to 3, c represents an integer from 0 to 3, (a + b + c) is 3.

[0158] The branching agent represented by formula (3) is not particularly limited, and examples include: trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, trimethoxy(2-vinylphenyl)silane, triethoxy(2-vinylphenyl)silane, tripropoxy(2-vinylphenyl)silane, tributoxy (2-Vinylphenyl)silane, triisopropoxy(2-vinylphenyl)silane, dimethoxymethyl(4-vinylphenyl)silane, diethoxymethyl(4-vinylphenyl)silane, dipropoxymethyl(4-vinylphenyl)silane, dibutoxymethyl(4-vinylphenyl)silane, diisopropoxymethyl(4-vinylphenyl)silane, dimethoxymethyl(3-vinylphenyl)silane, dipropoxymethyl(3-vinylphenyl)silane, dibutoxymethyl(3-vinylphenyl)silane, diisopropoxymethyl(3-vinylphenyl)silane, dimethoxymethyl(2-vinylphenyl)silane, diethoxymethyl(2-vinylphenyl)silane, dipropoxymethyl oxymethyl (2-vinylphenyl)silane, dibutoxymethyl (2-vinylphenyl)silane, diisopropoxymethyl (2-vinylphenyl)silane, dimethylmethoxy (4-vinylphenyl)silane, dimethylethoxy (4-vinylphenyl)silane, dimethylpropoxy (4-vinylphenyl)silane, dimethylbutoxy (4-vinylphenyl)silane, dimethylisopropoxy (4-vinylphenyl)silane, dimethylmethoxy (3-vinylphenyl)silane, dimethylethoxy (3-vinylphenyl)silane, dimethylpropoxy (3-vinylphenyl)silane, dimethylbutoxy (3-vinylphenyl)silane, dimethylisopropoxy (3-vinylphenyl)silane, dimethylmethoxy (2-vinylphenyl)silane Silane, dimethylethoxy(2-vinylphenyl)silane, dimethylpropoxy(2-vinylphenyl)silane, dimethylbutoxy(2-vinylphenyl)silane, dimethylisopropoxy(2-vinylphenyl)silane, trimethoxy(4-isopropenylphenyl)silane, triethoxy(4-isopropenylphenyl)silane, tripropoxy(4-isopropenylphenyl)silane, tributoxy(4-isopropenylphenyl)silane, triisopropoxy(4-isopropenylphenyl)silane, trimethoxy(3-isopropenylphenyl)silane, triethoxy(3-isopropenylphenyl)silane, tripropoxy(3-isopropenylphenyl)silane, tributoxy(3-isopropenylphenyl)silane, triisopropoxy(3-isopropenylphenyl)silane, triisopropoxy(3-isopropenylphenyl)silaneTrimethoxy(2-isopropenylphenyl)silane, Triethoxy(2-isopropenylphenyl)silane, Tripropoxy(2-isopropenylphenyl)silane, Tributoxy(2-isopropenylphenyl)silane, Triisopropoxy(2-isopropenylphenyl)silane, Dimethoxymethyl(4-isopropenylphenyl)silane, Diethoxymethyl(4-isopropenylphenyl)silane, Dipropoxymethyl(4-isopropenylphenyl)silane, Dibutoxymethyl(4-isopropenylphenyl)silane, Diisopropoxymethyl(4-isopropenylphenyl)silane, Dimethoxymethyl(3-isopropenylphenyl)silane, Diethoxymethyl(3-isopropenylphenyl)silane, Dipropoxymethyl(3-isopropenylphenyl)silane Silane, dibutoxymethyl(3-isopropenylphenyl)silane, diisopropoxymethyl(3-isopropenylphenyl)silane, dimethoxymethyl(2-isopropenylphenyl)silane, diethoxymethyl(2-isopropenylphenyl)silane, dipropoxymethyl(2-isopropenylphenyl)silane, dibutoxymethyl(2-isopropenylphenyl)silane, diisopropoxymethyl(2-isopropenylphenyl)silane, dimethylmethoxy(4-isopropenylphenyl)silane, dimethylethoxy(4-isopropenylphenyl)silane, dimethylpropoxy(4-isopropenylphenyl)silane, dimethylbutoxy(4-isopropenylphenyl)silane, dimethylisopropoxy(4-isopropenylphenyl)silane Dimethylmethoxy(3-isopropenylphenyl)silane, dimethylethoxy(3-isopropenylphenyl)silane, dimethylpropoxy(3-isopropenylphenyl)silane, dimethylbutoxy(3-isopropenylphenyl)silane, dimethylisopropoxy(3-isopropenylphenyl)silane, dimethylmethoxy(2-isopropenylphenyl)silane, dimethylpropoxy(2-isopropenylphenyl)silane, dimethylbutoxy(2-isopropenylphenyl)silane, dimethylisopropoxy(2-isopropenylphenyl)silane, trichloro(4-vinylphenyl)silane, trichloro(3-vinylphenyl)silane, trichloro(2-vinylphenyl)silane, Tribromo(4-vinylphenyl)silane, tribromo(3-vinylphenyl)silane, tribromo(2-vinylphenyl)silane, dichloromethyl(4-vinylphenyl)silane, dichloromethyl(3-vinylphenyl)silane, dichloromethyl(2-vinylphenyl)silane, dibromomethyl(4-vinylphenyl)silane, dibromomethyl(3-vinylphenyl)silane, dibromomethyl(2-vinylphenyl)silane, dimethylchloro(4-vinylphenyl)silane, dimethylchloro(3-vinylphenyl)silane, dimethylchloro(2-vinylphenyl)silane, dimethylbromo(4-vinylphenyl)silane, dimethylbromo(3-vinylphenyl)silane, and dimethylbromo(2-vinylphenyl)silane.

[0159] Among these, trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane, trimethoxy(3-vinylphenyl)silane, triethoxy(3-vinylphenyl)silane, tripropoxy(3-vinylphenyl)silane, tributoxy(3-vinylphenyl)silane, triisopropoxy(3-vinylphenyl)silane, and trichloro(4-vinylphenyl)silane are more preferred.

[0160] The branching agent represented by formula (4) is not particularly limited, and examples include: 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-tripropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, 1,1-bis(4-triisopropoxysilylphenyl)ethylene 1,1-bis(3-trimethoxysilylphenyl)ethylene, 1,1-bis(3-triethoxysilylphenyl)ethylene, 1,1-bis(3-tripropoxysilylphenyl)ethylene, 1,1-bis(3-tripentoxysilylphenyl)ethylene, 1,1-bis(3-triisopropoxysilylphenyl)ethylene, 1,1-bis(2-trimethoxysilylphenyl)ethylene, 1,1-bis(2-tri-trimethoxysilylphenyl)ethylene Ethoxysilylphenyl)ethylene, 1,1-bis(3-tripropoxysilylphenyl)ethylene, 1,1-bis(2-tripentoxysilylphenyl)ethylene, 1,1-bis(2-triisopropoxysilylphenyl)ethylene, 1,1-bis(4-(dimethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dipropyl) 1,1-bis(4-(dimethylethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylethoxysilyl)phenyl)ethylene, and 1,1-bis(4-(dipropylethoxysilyl)phenyl)ethylene, 1,1-bis(4-(methyldimethoxysilyl)phenyl)ethylene, 1,1-bis(4-(ethyldiethoxysilyl)phenyl)ethylene.

[0161] Among these, 1,1-bis(4-trimethoxysilylphenyl)ethylene, 1,1-bis(4-triethoxysilylphenyl)ethylene, 1,1-bis(4-tripropoxysilylphenyl)ethylene, 1,1-bis(4-tripentoxysilylphenyl)ethylene, and 1,1-bis(4-triisopropoxysilylphenyl)ethylene are preferred, and 1,1-bis(4-trimethoxysilylphenyl)ethylene is even more preferred.

[0162] In this embodiment, the modified conjugated diene polymer preferably has a main chain branch structure having monomer units derived from the compound represented by formula (3) above, where R1 represents a hydrogen atom and m represents 0. This achieves the following effects: increased branch number, suppression of cold flow in the packaging as a product of the conjugated diene polymer, excellent processability when made into a sulfurized product, and excellent wear resistance and breaking strength after sulfurization.

[0163] In this embodiment, the modified conjugated diene polymer preferably has a main chain branch structure having monomer units derived from the compound represented by formula (4) above, where m represents 0 and b represents 0. This allows for improved wear resistance and processability.

[0164] In this embodiment, the modified conjugated diene polymer is preferably such that the main chain branch structure has monomer units derived from the compound represented by formula (3) above, and in formula (3), R1 represents a hydrogen atom, m represents 0, n represents 3, and l represents 0. This improves the modification rate and branching degree, suppresses cold flow in the packaging as an article of the conjugated diene polymer, and achieves improved fuel efficiency, wear resistance, and processability.

[0165] In this embodiment, the modified conjugated diene polymer preferably has a main chain branch structure having monomer units derived from the compound represented by formula (4) above, where m represents 0, n represents 3, l represents 0, a represents 0, b represents 0, and c represents 3. This suppresses cold flow in the packaging, which is the product form of the conjugated diene polymer, and improves wear resistance and processability.

[0166] <<Rubber Composition, Vulcanized Rubber Composition>> The rubber composition of this embodiment can be vulcanized into a vulcanized rubber composition by vulcanization. In other words, the vulcanized rubber composition of this embodiment is a composition obtained by vulcanizing a rubber composition containing a modified conjugated diene polymer.

[0167] (Silane Coupling Agent) When the rubber composition of this embodiment contains silica as a filler, it may also contain a silane coupling agent. The silane coupling agent has the function of making the interaction between the rubber component and the inorganic filler more intense. Preferably, it is a compound having a group that has affinity or bonding with both the rubber component and the silica-based inorganic filler, and having a sulfur bond moiety and an alkoxysilyl or silanol moiety in one molecule. There are no particular limitations on such compounds; examples include bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0168] In the rubber composition of this embodiment, the content of the silane coupling agent relative to 100 parts by weight of the aforementioned silicon dioxide-based inorganic filler is preferably 0.1 parts by weight or more and 30 parts by weight or less, more preferably 0.5 parts by weight or more and 20 parts by weight or less, and even more preferably 1.0 parts by weight or more and 15 parts by weight or less. If the content of the silane coupling agent is within the above range, there is a tendency to make the above-mentioned additive effect obtained by the silane coupling agent more significant.

[0169] (Rubber softener) From the viewpoint of improving the processability of the rubber composition of this embodiment, it may also include a rubber softener.

[0170] The amount of rubber softener added is expressed relative to 100 parts by mass of the rubber component containing the above-mentioned conjugated diene polymer, including the amount of rubber softener contained in the above-mentioned conjugated diene polymer or other rubbery polymer, and the total amount of rubber softener added when preparing the crosslinked rubber composition.

[0171] Mineral oil, or liquid or low molecular weight synthetic softeners are more suitable as rubber softeners.

[0172] Mineral oil-based rubber softeners, also known as processing oils or thickening oils, used to soften, compatibilize, and improve the processability of rubber, are mixtures of aromatic rings, cycloalkane rings, and alkane chains. Alkane chains comprising 50% or more of the total carbon atoms are called alkane chains; cycloalkane chains comprising 30% to 45% of the total carbon atoms are called cycloalkane chains; and aromatic chains comprising more than 30% of the total carbon atoms are called aromatic chains. In the case where the conjugated diene polymer of this embodiment is a copolymer of a conjugated diene compound and a vinyl aromatic compound, a rubber softener with an appropriate aromatic content tends to have good affinity with the copolymer, and is therefore preferred.

[0173] In the rubber composition of this embodiment, the content of the rubber softener relative to 100 parts by mass of the rubber component is preferably 0 parts by mass or less than 100 parts by mass, more preferably 5 parts by mass or less than 90 parts by mass, and even more preferably 10 parts by mass or less than 80 parts by mass. By keeping the content of the rubber softener relative to 100 parts by mass of the rubber component at 100 parts by mass or less, there is a tendency to suppress exudation and reduce the stickiness of the surface of the rubber composition.

[0174] (Method for Manufacturing Rubber Composition) There are no particular limitations on the method for manufacturing the rubber composition of this embodiment. Examples include: melt mixing of conjugated diene polymers and other rubbery polymers, carbon black, silica-based inorganic fillers or other fillers, silane coupling agents, rubber softeners, and other additives using a conventional mixer such as an open-end roller, a Bamboo mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder; and methods involving removing the solvent by heating after dissolving and mixing the components. From the viewpoint of productivity and good mixing properties, melt mixing using a roller, a Bamboo mixer, a kneader, or an extruder is preferred. Furthermore, methods involving mixing the rubber components with other fillers, silane coupling agents, and additives in a single step, or methods involving mixing in multiple steps, are also applicable.

[0175] The rubber composition of this embodiment can be used to prepare a vulcanized rubber composition (hereinafter, sometimes referred to as a "vulcanized composition") obtained by vulcanization treatment using a vulcanizing agent. The vulcanizing agent is not particularly limited, but examples include: free radical generating agents such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds. Sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, and high-molecular-weight polysulfide compounds. In the rubber composition of this embodiment, the content of the vulcanizing agent relative to 100 parts by weight of the rubber component is preferably 0.01 parts by weight to 20 parts by weight, and more preferably 0.1 parts by weight to 15 parts by weight. As for the vulcanization method, previously known methods can be used, and the vulcanization temperature is preferably 120°C to 200°C, and more preferably 140°C to 180°C.

[0176] When vulcanizing, a vulcanizing accelerator may also be used as needed. Previously known materials can be used as vulcanizing accelerators without particular limitation, such as: sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-amine-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanizing accelerators. Furthermore, there are no particular limitations on vulcanizing additives; for example: zinc oxide and stearic acid. The content of the vulcanizing accelerator relative to 100 parts by weight of the rubber component is preferably 0.01 parts by weight to 20 parts by weight, more preferably 0.1 parts by weight to 15 parts by weight.

[0177] In the rubber composition of this embodiment, other softeners and fillers, heat stabilizers, antistatic agents, weather stabilizers, anti-aging agents, colorants, lubricants, and other additives may also be used within the scope not impairing the purpose of the present invention. As other softeners, known softeners can be used. As other fillers, there are no particular limitations; examples include calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. As the aforementioned heat stabilizers, antistatic agents, weather stabilizers, anti-aging agents, colorants, and lubricants, known materials can be used respectively.

[0178] The rubber composition of this embodiment is suitable for use as a tire rubber composition. That is, the tire of this embodiment contains the rubber composition of this embodiment or a vulcanized rubber composition.

[0179] As a tire rubber composition, there are no particular limitations. For example, it can be used in various parts of tires such as the tread, carcass, sidewall, and bead of various tires, including fuel-efficient tires, all-season tires, high-performance tires, studless anti-skid tires, and tires for high-load vehicles. In particular, the tire rubber composition, after being vulcanized, exhibits excellent balance between abrasion resistance, breaking strength, low hysteresis loss, and wet skid resistance, making it suitable for use as the tread of fuel-efficient tires, high-performance tires, and tires for high-load vehicles.

[0180] Furthermore, the rubber composition of this embodiment, in addition to its use in tires, is also industrially applicable as vibration-damping rubber, vibration-proof rubber, conveyor belts, shoe outsoles, automotive sealing strips, gaskets or washers, sealing materials, waterproof sheets, engine frames, air springs, rubber gloves, medical and hygiene products, industrial and various other hoses, battery boxes, adhesives, wire sheathing, window frame rubber, rubber stoppers, rubber rollers, and materials for various industrial products. [Example]

[0181] Hereinafter, specific embodiments and comparative examples will be given to further describe this embodiment in detail, but this embodiment is not limited to the following embodiments and comparative examples.

[0182] The various physical properties of the examples and comparative examples were measured by the methods shown below.

[0183] (Physical Property 1) Munich Viscosity: The Munich viscosity was measured using a Munich viscometer (a product manufactured by Uejima Corporation called "VR1132"), in accordance with ISO 289, using an L-shaped rotor. The measurement temperature was set to 100°C. First, the sample was preheated at the test temperature for 1 minute, and then the rotor was rotated at 2 rpm. The torque after 4 minutes was measured and set as the Munich viscosity (ML (Physical Property 1)). Table 1 shows the measurement results of the Munich viscosity (100°C) before modification and the Munich viscosity (100°C) after modification.

[0184] (Physical Property 2) Microstructure of Conjugated Diene Polymers (1,2-Vinyl Bond Content) When the (modified) conjugated diene polymer is polybutadiene, the (modified) conjugated diene polymer is used as a sample. 50 mg of the sample is dissolved in 10 mL of carbon disulfide to prepare the test sample. Using a solution cell, the infrared spectrum is measured in the range of 600–1000 cm⁻¹. Based on the absorbance at the specified wavenumber, the 1,2-vinyl bond content (mol%) of the conjugated diene polymer is calculated according to the Morero method (D. Morero, A. Santambrogio, L. Porri, F. Clampelli: Chim. e Ind., 41, 758 (1959)). (Measurement Apparatus: Fourier Transform Infrared Spectrophotometer "FT-IR230" manufactured by Nippon Spectrophotometer Co., Ltd.)

[0185] When the (modified) conjugated diene polymer is a styrene-butadiene copolymer, the determination is performed in the same manner as for the polybutadiene described above. The microstructure of the butadiene moiety, i.e., the amount of 1,2-vinyl bonds (mol%), is determined according to the absorbance at a specified wavenumber and the calculation formula of the Hampton method (RR Hampton, Analytical Chemistry 21,923 (1949)).

[0186] (Physical Property 3) Bonded Styrene Content (Styrene Content; Aromatic Vinyl Bond Content) A (modified) conjugated diene polymer was used as a sample. 100 mg of the sample was diluted to 100 mL with chloroform and dissolved to prepare the test sample. The bonded styrene content (mass%) relative to 100% by mass of the modified conjugated diene polymer used as the sample was determined based on the absorbance at the ultraviolet absorption wavelength (around 254 nm) obtained by the phenyl group of styrene (Shimadzu UV-2450 spectrophotometer).

[0187] (Physical Property 4) Glass Transition Temperature Using the (modified) conjugated diene polymer as the sample, DSC was performed according to ISO 22768:2006 using a differential scanning calorimeter (NETZSCH "DSC3500"). The DSC curve was recorded while the temperature was increased from -130°C at a flow rate of 50 mL / min under helium conditions. The peak (inflection point) of the DSC differential curve was set as the glass transition temperature (Tg).

[0188] (Physical Property 5) Branching Degree (Bn) The branching degree (Bn) of the (modified) conjugated diene polymer was determined by GPC-light scattering method with a viscosity detector, as follows. The (modified) conjugated diene polymer was used as the sample, and a gel permeation chromatography (GPC) apparatus (a product named "GPCmax VE-2001" manufactured by Malvern) was used, which was connected in the order of light scattering detector, RI detector, and viscosity detector (a product named "TDA305" manufactured by Malvern). Based on standard polystyrene, the absolute molecular weight was determined from the results of the light scattering detector and RI detector, and the intrinsic viscosity was determined from the results of the RI detector and viscosity detector.

[0189] The linear polymer was used as a shrinkage factor (g') calculated as the ratio of the intrinsic viscosity to the intrinsic viscosity corresponding to each molecular weight, based on the intrinsic viscosity [η] = 10⁻³.883 × M⁰.77. Furthermore, M represents the absolute molecular weight. Then, using the obtained shrinkage factor (g'), the branching degree (Bn) was calculated, defined as g' = 6Bn / {(Bn+1)(Bn+2)}. The precipitate was tetrahydrofuran (hereinafter also referred to as "THF") containing 5 mmol / L triethylamine. The column was connected to commercial products manufactured by Tosoh Corporation named "TSKgel G4000HXL", "TSKgel G5000HXL", and "TSKgel G6000HXL". The test sample of 20 mg was dissolved in 10 mL of THF to prepare the test solution. 100 μL of the test solution was injected into the GPC test device and the test was performed at an oven temperature of 40°C and a THF flow rate of 1 mL / min.

[0190] (Physical Property 6) Molecular Weight (Weight Average Molecular Weight, Number Average Molecular Weight, Mw / Mn) Determination Condition 1: The (modified) conjugated diene polymer was used as the sample. A GPC measuring device (manufactured by Tosoh Corporation, named "HLC-8320GPC") with three columns connected to polystyrene gel as the filler was used to measure the chromatogram. The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were determined based on the calibration curve obtained using standard polystyrene.

[0191] The elution solution used was THF (tetrahydrofuran) containing 5 mmol / L of triethylamine. The column was connected to three Tosoh Corporation products called "TSKgel SuperMultiporeHZ-H" and connected to Tosoh Corporation products called "TSKguardcolumn SuperMP(HZ)-H" at the front end as a protection column.

[0192] Dissolve 10 mg of the sample to be measured in 10 mL of THF to prepare a test solution. Inject 10 μL of the test solution into the GPC test apparatus and perform the test at an oven temperature of 40°C and a THF flow rate of 0.35 mL / min.

[0193] Samples whose molecular weight distribution (Mw / Mn) value measured under the above-described test conditions 1 is less than 1.6 shall be re-measured under the following test conditions 2. For samples whose molecular weight distribution value measured under test conditions 1 is 1.6 or higher, the value obtained under test conditions 1 shall be used.

[0194] Determination Condition 2: Using a conjugated diene polymer or a coupled conjugated diene polymer as a sample, a GPC assay apparatus with three columns connected to a polystyrene gel as a filler is used to measure the chromatogram. Based on the calibration curve obtained using standard polystyrene, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are determined.

[0195] The elution buffer used was THF containing 5 mmol / L triethylamine. Regarding the columns, the following were used: the guard column, "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation; and the columns, "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" manufactured by Tosoh Corporation.

[0196] Under the conditions of oven temperature 40°C and THF flow rate 0.6 mL / min, an RI detector (a product manufactured by Tosoh Corporation named "HLC8020") was used. 10 mg of the sample to be measured was dissolved in 20 mL of THF to prepare a test solution, and 20 μL of the test solution was injected into the GPC measuring device for measurement.

[0197] (Physical Property 7) The modification rate was determined by column adsorption GPC method as follows: The modified rate of the conjugated diene polymer was used as a sample. The modified basic polymer component was adsorbed onto the GPC column with silica gel as the filler, and the modification rate was determined by this method.

[0198] For a sample solution containing the sample and low molecular weight internal standard polystyrene, the amount of adsorption on the silicon dioxide column is determined based on the difference between the chromatogram measured by the polystyrene column and the chromatogram measured by the silicon dioxide column, and the modification rate is calculated.

[0199] Specifically, as shown below. Furthermore, for samples whose molecular weight distribution value is 1.6 or higher as determined by the above-mentioned (physical property 4) determination conditions 1, the determination is carried out under the following determination conditions 3; for samples whose molecular weight distribution value is less than 1.6, the determination is carried out under the following determination conditions 4.

[0200] Preparation of sample solution: Dissolve 10 mg of sample and 5 mg of standard polystyrene in 20 mL of THF to prepare sample solution.

[0201] Determination Conditions 3: GPC determination using a polystyrene-based column: A commercial product named "HLC-8320GPC" manufactured by Tosoh Corporation was used, with THF containing 5 mmol / L triethylamine as the chromatographic solvent. 10 μL of the sample solution was injected into the apparatus. The chromatography was obtained using an RI detector under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.35 mL / min. The column consisted of three commercial products named "TSKgel SuperMultiporeHZ-H" manufactured by Tosoh Corporation, with a "TSKguardcolumn SuperMP(HZ)-H" manufactured by Tosoh Corporation connected to the front end as a guard column.

[0202] Determination Condition 4: Using THF containing 5 mmol / L triethylamine as the elution solution, 20 μL of the sample solution was injected into the apparatus for determination. Regarding the columns, the following were used: guard column: "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation; and columns: "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" manufactured by Tosoh Corporation. Chromatography was obtained using an RI detector (HLC8020 manufactured by Tosoh Corporation) at a column oven temperature of 40°C and a THF flow rate of 0.6 mL / min.

[0203] GPC determination conditions using silicon dioxide-based columns: Tosoh Corporation's "HLC-8320GPC" was used, with THF as the precipitate. 50 μL of the sample solution was injected into the apparatus, and the chromatography was obtained using an RI detector at a column oven temperature of 40°C and a THF flow rate of 0.5 ml / min. The columns were connected to "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S" products, with a "DIOL 4.6×12.5mm 5micron" product connected to the front end as a guard column.

[0204] Calculation method of modification rate: Set the peak area of ​​the chromatogram obtained using the polystyrene-based column to 100, set the peak area of ​​the sample to P1, set the peak area of ​​the standard polystyrene to P2, set the peak area of ​​the chromatogram obtained using the silicon dioxide-based column to 100, set the peak area of ​​the sample to P3, set the peak area of ​​the standard polystyrene to P4, and calculate the modification rate (%) according to the following formula.

[0205] Modification rate (%) = [1 - (P2 × P3) / (P1 × P4)] × 100 (where, P1 + P2 = P3 + P4 = 100)

[0206] (Physical Property 8) Hydrogenation Rate: A (modified) conjugated diene polymer without antioxidants was used as the sample. 50 mg of the sample was dissolved in 1 mL of deuterated chloroform to prepare the test sample. The measurement was performed using a nuclear magnetic resonance (¹H-NMR) apparatus (JEOL Corporation, named "JNM-LA400") at an observation frequency of 400 MHz, a pulse delay of 2.904 seconds, a cumulative count of 64, a pulse width of 45°, and a measurement temperature of 26°C. The hydrogenation rate of the double bonds in the structural units derived from 1,3-butadiene was determined by the chemical shift of TMS (tetramethylsilane) as the reference material, based on the composition ratio (mol%) of the 1,4-bond structural units, 1,2-bond structural units, hydrogenated 1,4-bond structural units, and hydrogenated 1,2-bond structural units derived from 1,3-butadiene.

[0207] (Synthesis Example 1) Modified conjugated diene polymer (sample 1) Two trough-type pressure vessels are connected to form a polymerization reactor. The trough-type pressure vessel has an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom, an outlet at the top, and is a trough-type reactor equipped with a stirrer and a jacket for temperature control.

[0208] 1,3-Butadiene, which had been pre-moistened, was mixed at a rate of 30.8 g / min with n-hexane at a rate of 189.3 g / min. In a static mixer located midway through the piping supplying this mixture to the reactor inlet, n-butyllithium for residual impurity inert treatment was added at a rate of 0.072 mmol / min and mixed, and then continuously supplied to the bottom of the reactor. Next, 2,2-bis(2-tetrahydrofuranyl)propane, as a polar substance, was supplied at a rate of 0.027 mmol / min, and n-butyllithium, as a polymerization initiator, was supplied to the bottom of the first reactor, which was being vigorously mixed by a stirrer, and the reactor temperature was maintained at 78°C.

[0209] The polymer solution was continuously drawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, where the reaction continued at 78°C. The solution was then fed from the top of the second reactor to a static mixer. When the polymerization was sufficiently stable, 1,3-butadiene polymerization was carried out while trimethoxy(4-vinylphenyl)silane (referred to as "BS-1" in the table) was added from the bottom of the second reactor as a branching agent at a rate of 0.030 mmol / min to obtain a conjugated diene polymer with a branched structure. Then, when the polymerization and branching reactions were stable, a small amount of the conjugated diene polymer solution before the addition of the modifier was drawn off, and an antioxidant (BHT) was added at a rate of 0.2 g per 100 g of polymer. The solvent was then removed, and the Munich viscosity of the conjugated diene polymer was measured. The results are shown in Table 1.

[0210] Subsequently, 1,3-dimethylimidazolone (abbreviated as "A" in the table) as a modifier was continuously added to the polymer solution flowing out of the reactor outlet at a rate of 0.155 mmol / min, and the mixture was stirred using a static mixer to carry out the modification reaction. At this time, the time until the modifier was added to the polymer solution flowing out of the reactor outlet was 4.8 minutes, the temperature was 76°C, and the temperature difference between the temperature during the polymerization process and the temperature until the modifier was added was 2°C.

[0211] Subsequently, an antioxidant (BHT) was continuously added to the modified polymer solution at a rate of 0.2 g per 100 g of polymer at a rate of 0.055 g / min (n-hexane solution) to terminate the modification reaction. The solvent was then removed by steam stripping to obtain a modified conjugated diene polymer (sample 1) with a 4-branched structure in a portion of the main chain derived from trimethoxy(4-vinylphenyl)silane (the compound represented by formula (3) above), and various physical properties of the sample were measured. The results are shown in Table 1.

[0212] The structure of the modified conjugated diene polymer was identified by comparing the molecular weight obtained by GPC with the degree of branching obtained by GPC using an adhesion viscometer for the polymer before the addition of the branching agent, the polymer after modification with ... and the polymer after modification with the addition of the branching agent, the polymer after modification with the addition of the branching agent, the polymer after modification with the addition of the branching agent, and the polymer after modification with the addition of the branching agent, the polymer after modification with the addition of the branching agent, the polymer after modification with the addition of the branching agent, the

[0213] (Synthesis Examples 2-9) Modified Conjugated Diene Polymers (Samples 2-9) Except for changing the manufacturing conditions of Example 1 to the manufacturing conditions of Examples 2-9 shown in Table 1, the same operation as in Synthesis Example 1 was performed to obtain modified conjugated diene polymers (Samples 2-9). Various physical properties of the samples were measured. The results are shown in Table 1. "BS-2" to "BS-3" and "B" shown as branching agents and modifiers in the table represent the following compounds respectively. "BS-2": Dimethylmethoxy(4-vinylphenyl)silane "BS-3": 1,1-bis(4-(methyldimethoxysilyl)phenyl)ethylene (the compound represented by formula (4) above) "B": N-methyl-2-pyrrolidone

[0214] (Adjustment of Hydrogenation Catalyst) A tank-type pressure vessel with a stirrer, having been pre-purified with nitrogen and having an internal height (L) to diameter (D) ratio (L / D) of 4.0, was used as a mixing tank. 3200 g of pre-purified and dehydrated cyclohexane was supplied to the mixing tank. Then, 250 mmol of bis(n-5-cyclopentadienyl)titanium dichloride was added. While stirring thoroughly, 500 mmol of trimethylaluminum (1.4 mol / L, n-hexane solution) was added, and the reaction was allowed to proceed at room temperature for 3 days to obtain the hydrogenation catalyst.

[0215] (Synthesis Example 10) Modified conjugated diene polymer (sample 10) Two trough-type pressure vessels are connected to form a polymerization reactor. The trough-type pressure vessel has an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom, an outlet at the top, and is a trough-type reactor equipped with a stirrer and a jacket for temperature control.

[0216] 1,3-Butadiene, which had been pre-moistened, was mixed at a rate of 30.8 g / min with n-hexane at a rate of 189.3 g / min. In a static mixer located midway through the piping supplying this mixture to the reactor inlet, n-butyllithium for residual impurity inert treatment was added at a rate of 0.072 mmol / min and mixed, and then continuously supplied to the bottom of the reactor. Next, 2,2-bis(2-tetrahydrofuranyl)propane, as a polar substance, was supplied at a rate of 0.027 mmol / min, and n-butyllithium, as a polymerization initiator, was supplied at a rate of 0.205 mmol / min to the bottom of the first reactor, which was being vigorously mixed by a stirrer, and the reactor temperature was maintained at 78°C.

[0217] The polymer solution was continuously drawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, where the reaction continued at 78°C. The solution was then fed from the top of the second reactor to a static mixer. When the polymerization was sufficiently stable, 1,3-butadiene polymerization was carried out while trimethoxy(4-vinylphenyl)silane (referred to as "BS-1" in the table) was added from the bottom of the second reactor as a branching agent at a rate of 0.030 mmol / min to obtain a conjugated diene polymer with a branched structure. Then, when the polymerization and branching reactions were stable, a small amount of the conjugated diene polymer solution before the addition of the modifier was drawn off, and an antioxidant (BHT) was added at a rate of 0.2 g per 100 g of polymer. The solvent was then removed, and the Munich viscosity of the conjugated diene polymer was measured. The results are shown in Table 1.

[0218] Subsequently, 1,3-dimethylimidazolone (abbreviated as "A" in the table) as a modifier was continuously added to the polymer solution flowing out of the reactor outlet at a rate of 0.155 mmol / min, and the mixture was stirred using a static mixer to carry out the modification reaction. At this time, the time until the modifier was added to the polymer solution flowing out of the reactor outlet was 4.8 minutes, the temperature was 76°C, and the temperature difference between the temperature during the polymerization process and the temperature until the modifier was added was 2°C.

[0219] Next, a tank-type pressure vessel of the same type used as a polymerization reactor was connected as a hydrogenation reactor, and the modified polymer solution was continuously supplied to the bottom of the hydrogenation reactor. Then, the hydrogenation catalyst synthesized above was continuously added at a rate of 30 ppm / min (based on titanium atoms) relative to 100 parts by mass of the conjugated diene polymer, and hydrogen was added at a rate of 768 ml / min (the hydrogenation rate of the butadiene-derived double bonds in the conjugated diene polymer is equivalent to 6 mol%), and the hydrogenation reaction was continuously carried out. At this time, the pressure of the hydrogenation reactor was 0.50 MPa, and the temperature inside the reactor was 75°C.

[0220] When the hydrogenation reaction was stable, an antioxidant (BHT) was continuously added to the hydrogenated polymer solution at a rate of 0.2 g per 100 g of polymer at a rate of 0.055 g / min (n-hexane solution) to end the hydrogenation reaction. Subsequently, the solvent was removed by steam stripping to obtain a modified conjugated diene polymer (sample 10) in which a portion of the main chain has a 4-branched structure derived from trimethoxy(4-vinylphenyl)silane (the compound represented by formula (3) above) and a portion of the conjugated diene polymer was partially hydrogenated, and various physical properties of the sample were measured. The results are shown in Table 1.

[0221] (Comparative Synthesis Example 1) Conjugated diene polymer (sample 11) Two trough-type pressure vessels are connected to form a polymerization reactor. The trough-type pressure vessel has an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom, an outlet at the top, and is a trough-type reactor equipped with a stirrer and a jacket for temperature control.

[0222] 1,3-Butadiene, which had been pre-moistened, was mixed at a rate of 30.8 g / min with n-hexane at a rate of 189.3 g / min. In a static mixer located midway through the piping supplying this mixture to the inlet of the reactive base, n-butyllithium for residual impurity inert treatment was added at a rate of 0.072 mmol / min and mixed, and then continuously supplied to the bottom of the reactor. Next, 2,2-bis(2-tetrahydrofuranyl)propane, as a polar substance, was supplied at a rate of 0.027 mmol / min, and n-butyllithium, as a polymerization initiator, was supplied to the bottom of the first reactor, which was being vigorously mixed by a stirrer, and the reactor temperature was maintained at 78°C.

[0223] The polymer solution was continuously drawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, where the reaction continued at 78°C. The solution was then fed from the top of the second reactor to a static mixer. When the polymerization reaction was sufficiently stable, a small amount of the conjugated diene polymer solution was drawn off, and an antioxidant (BHT) was added at a rate of 0.2 g per 100 g of polymer. The solvent was then removed, and the Munich viscosity of the conjugated diene polymer was measured. The results are shown in Table 2.

[0224] Subsequently, an antioxidant (BHT) was continuously added to the modified polymer solution at a rate of 0.2 g per 100 g of polymer at a rate of 0.055 g / min (n-hexane solution). The solvent was then removed by steam stripping to obtain the modified conjugated diene polymer (sample 11), and various physical properties were measured. The results are shown in Table 2.

[0225] (Comparative Synthesis Examples 2 and 3) Conjugated Diene Polymers (Samples 12 and 13) The manufacturing conditions of Comparative Synthesis Example 1 were changed to those of Comparative Synthesis Examples 2 and 3 shown in Table 2. When the polymerization reaction was sufficiently stable, a branching agent was added to carry out the polymerization and branching reactions to obtain conjugated diene polymers with branched structures. Subsequently, no modifier was added, and the operation was performed in the same manner as in Comparative Example 1 to obtain conjugated diene polymers (Samples 12 and 13), and various physical properties were measured. The measurement results are shown in Table 2.

[0226] (Comparative Synthesis Example 4) Modified Conjugated Diene Polymer (Sample 14) The manufacturing conditions of Comparative Synthesis Example 1 were changed to those of Comparative Synthesis Example 4 as shown in Table 2. When the polymerization reaction was sufficiently stable, a modifier was added, and the polymerization and modification reactions to obtain the conjugated diene polymer were carried out. Otherwise, the operation was the same as in Comparative Synthesis Example 1 to obtain the modified conjugated diene polymer (Sample 14), and various physical properties were measured. The measurement results are shown in Table 2.

[0227] (Comparative Synthesis Examples 5 and 6) Modified Conjugated Diene Polymers (Samples 15 and 16) The manufacturing conditions of Comparative Synthesis Example 1 were changed to the manufacturing conditions of Comparative Synthesis Examples 5 and 6 shown in Table 2. When the polymerization reaction was sufficiently stable, a branching agent was added to carry out the polymerization reaction and branching reaction to obtain conjugated diene polymers with branched structures. Subsequently, when the polymerization reaction and branching reaction were sufficiently stable, a modifier was added, and the operation was carried out in the same manner as in Comparative Synthesis Example 1 to obtain modified conjugated diene polymers (Samples 15 and 16), and various physical properties were measured. The measurement results are shown in Table 2. "BS-4" shown as a branching agent in the table represents the following compound. "BS-4": 1,1-bis(4-trimethoxysilylphenyl)ethylene

[0228] (Comparative Synthesis Example 7) Modified Conjugated Diene Polymer (Sample 17) A trough-type pressure vessel was used as the polymerization reactor. The trough-type pressure vessel had an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, and was equipped with a stirrer and a jacket for temperature control. 1050 g of 1,3-butadiene and 4780 g of n-hexane, which had been pre-moistened, were supplied to the reactor and stirred. Then, 0.01 mmol of 2,2-bis(2-tetrahydrofuranyl)propane, a polar substance, was added to the reactor and stirring continued, while the internal temperature of the reactor was controlled at 45°C. After confirming that the internal temperature of the reactor stabilized at 45°C while stirring, the warm water in the reactor jacket was removed, and 10.66 mmol of n-butyllithium, a polymerization initiator, was added to start the polymerization reaction. After polymerization began, the internal temperature of the reactor slowly rose, reaching a peak of 95°C after 21 minutes. Two minutes after reaching the peak, 1.33 mmol of trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added as a branching agent, and a branching reaction was carried out for 5 minutes. Subsequently, 6.40 mmol of 1,3-dimethylimidazolone (abbreviated as "A" in the table) was added as a modifier, and a modification reaction was carried out for 5 minutes. After the modification reaction, 10.00 mmol of ethanol was added to completely stop the reaction. Then, an antioxidant (BHT) was added to the polymer solution at a rate of 0.2 g per 100 g of polymer. The solvent was then removed by steam stripping to obtain a modified conjugated diene polymer containing a 4-branched structure (sample 17), and various physical properties of the sample were measured. The results are shown in Table 2.

[0229] (Comparative Synthesis Example 8) Conjugated diene polymer (sample 18) A high cis BR (Mounier viscosity (100°C): 43,1,2-vinyl bond amount: 1 mol%) manufactured by UBE Elastomer Co., Ltd. under the trade name "UBEPOL BR150" was prepared as (sample 18).

[0230] (Comparative Synthesis Example 9) Modified Conjugated Diene Polymer (Sample 19) The manufacturing conditions of Comparative Synthesis Example 1 were changed to those of Comparative Synthesis Example 9 shown in Table 2. When the polymerization reaction was sufficiently stable, a branching agent was added to carry out the polymerization reaction and branching reaction to obtain a conjugated diene polymer with a branched structure. Subsequently, when the polymerization reaction and branching reaction were sufficiently stable, a modifier was added, and the operation was carried out in the same manner as in Comparative Synthesis Example 1 to obtain a modified conjugated diene polymer (Sample 19), and various physical properties were measured. The measurement results are shown in Table 2. "BS-3" shown as a branching agent in the table represents the following compound. "BS-3": 1,1-bis(4-(methyldimethoxysilyl)phenyl)ethylene

[0231] (Comparative Synthesis Example 10) Modified Conjugated Diene Polymer (Sample 20) Two trough-type pressure vessels are connected to form a polymerization reactor. The trough-type pressure vessel has an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom, an outlet at the top, and is a trough-type reactor equipped with a stirrer and a jacket for temperature control.

[0232] 1,3-Butadiene, which had been pre-moistened, was mixed at a rate of 30.8 g / min with n-hexane at a rate of 189.3 g / min. In a static mixer located midway through the piping supplying this mixture to the reactor inlet, n-butyllithium for residual impurity inert treatment was added at a rate of 0.072 mmol / min and mixed, and then continuously supplied to the bottom of the reactor. Next, 2,2-bis(2-tetrahydrofuranyl)propane, as a polar substance, was supplied at a rate of 0.027 mmol / min, and n-butyllithium, as a polymerization initiator, was supplied at a rate of 0.205 mmol / min to the bottom of the first reactor, which was being vigorously mixed by a stirrer, and the reactor temperature was maintained at 78°C.

[0233] The polymer solution was continuously drawn from the top of the first reactor and continuously supplied to the bottom of the second reactor, where the reaction continued at 78°C. The solution was then fed from the top of the second reactor to a static mixer. When the polymerization was sufficiently stable, 1,3-butadiene polymerization was carried out while trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added from the bottom of the second reactor as a branching agent to obtain a conjugated diene polymer with a branched structure. Then, when the polymerization and branching reactions were stable, a small amount of the conjugated diene polymer solution before the addition of the modifier was drawn off, and an antioxidant (BHT) was added at a rate of 0.2 g per 100 g of polymer. The solvent was then removed, and the Munich viscosity of the conjugated diene polymer was measured. The results are shown in Table 2.

[0234] Subsequently, 1,3-dimethylimidazolone (abbreviated as "A" in the table) as a modifier was continuously added to the polymer solution flowing out of the reactor outlet at a rate of 0.155 mmol / min, and the mixture was stirred using a static mixer to carry out the modification reaction. At this time, the time until the modifier was added to the polymer solution flowing out of the reactor outlet was 4.8 minutes, the temperature was 76°C, and the temperature difference between the temperature during the polymerization process and the temperature until the modifier was added was 2°C.

[0235] Next, a tank-type pressure vessel of the same type used as a polymerization reactor was connected as a hydrogenation reactor, and the modified polymer solution was continuously supplied to the bottom of the hydrogenation reactor. Then, the hydrogenation catalyst synthesized above was continuously added at a rate of 30 ppm / min (based on titanium element) relative to 100 parts by mass of the conjugated diene polymer, and hydrogen was added continuously at a rate of 1536 ml / min (the hydrogenation rate of the butadiene-derived double bonds in the conjugated diene polymer is equivalent to 12 mol%), and the hydrogenation reaction was continuously carried out. At this time, the pressure of the hydrogenation reactor was 0.50 MPa, and the temperature inside the reactor was 75°C.

[0236] When the hydrogenation reaction was stable, an antioxidant (BHT) was continuously added to the hydrogenated polymer solution at a rate of 0.2 g per 100 g of polymer at a rate of 0.055 g / min (n-hexane solution) to end the hydrogenation reaction. Subsequently, the solvent was removed by steam stripping to obtain a modified conjugated diene polymer (sample 20) in which a portion of the main chain has a 4-branched structure derived from trimethoxy(4-vinylphenyl)silane (the compound represented by formula (3) above) and a portion of the conjugated diene polymer was hydrogenated, and various physical properties of the sample were measured. The results are shown in Table 2.

[0237] (Comparative Synthesis Example 11) Modified Conjugated Diene Polymer (Sample 21) The hydrogenation rate during the hydrogenation reaction was changed from 1536 ml / min to 4470 ml / min (equivalent to 35 moles of hydrogenation rate for the butadiene-derived double bonds in the conjugated diene polymer) under the same conditions as in Comparative Synthesis Example 10, to obtain the modified conjugated diene polymer (Sample 21), and various physical properties were measured. The results are shown in Table 2.

[0238] [Table 1] Synthesis example 1 Synthesis example 2 Synthesis example 3 Synthesis example 4 Synthesis example 5 Synthesis example 6 Synthesis Example 7 Synthesis example 8 Synthesis example 9 Synthesis example 10 Modified conjugated diene polymers (Sample No.) 1 2 3 4 5 6 7 8 9 10 Aggregation conditions butadiene (g / minute) 30.8 30.8 30.8 30.8 30.8 29.0 30.8 24.6 30.8 30.8 styrene (g / minute) 0 0 0 0 0 1.8 0 6.2 0 0 n-Hexane (g / minute) 189.3 189.3 189.3 189.3 189.3 189.3 189.3 189.3 189.3 189.3 Polymerization temperature (°C) 78 78 78 78 78 78 78 78 78 78 Processing n-butyllithium (mmol / min) 0.072 0.072 0.072 0.072 0.072 0.072 0.072 0.072 0.072 0.072 Polymerization-initiated n-butyllithium (mmol / min) 0.205 0.205 0.205 0.205 0.205 0.205 0.205 0.205 0.205 0.205 Amount of polar substances added (mmol / min) 0.027 0.027 0.027 0.027 0.027 0.027 0.027 0.027 0.081 0.027 branching agent type BS-1 BS-1 BS-2 BS-2 BS-3 BS-1 BS-1 BS-1 BS-1 BS-1 Added amount (mmol / min) 0.030 0.030 0.060 0.060 0.024 0.030 0.030 0.030 0.030 0.03 Modifier type A B A B A A A A A A Added amount (mmol / min) 0.155 0.155 0.155 0.155 0.155 0.155 0.093 0.155 0.155 0.155 Analysis values (Physical Property 1) Munich viscosity before modification (100℃) 58 58 56 56 64 58 58 58 58 58 Modified conjugated diene polymers (Physical Property 1) Modified Munich viscosity (100℃) 63 61 62 60 71 61 60 63 61 64 (Physical Property 2) 1,2-Vinyl Bond Weight (mol%) 17 17 17 17 17 16 17 15 32 12 (Physical Property 3) Styrene content (quality%) 0 0 0 0 0 5.5 0 19.5 0 0 (Property 4) Glass transition temperature (°C) -89.6 -89.6 -89.6 -89.6 -89.6 -83.2 -89.6 -64.3 -76.5 -88.8 (Physical Property 5) Branching Degree Bn per molecule 1.7 1.8 1.3 1.3 3.5 1.7 1.8 1.8 1.9 1.7 (Physical Property 7) Modification Rate (quality%) 81 77 80 76 83 80 47 79 83 81 (Physical Property 6) Weight Average Molecular Weight (10 4 g / mol) 46.0 45.4 45.7 45.1 48.6 45.4 45.1 46.0 45.4 46.0 (Physical Property 6) Number Average Molecular Weight (10 4 g / mol) 24.6 24.0 24.5 24.0 26.7 23.9 23.5 25.2 24.2 24.6 (Physical property 6)Mw / Mn 1.87 1.89 1.87 1.88 1.82 1.91 1.92 1.83 1.88 1.87 (Physical Property 8) Hydrogenation Rate 0 0 0 0 0 0 0 0 0 4.6

[0239] [Table 2] Comparative Synthesis Example 1 Comparative Synthesis Example 2 Comparative Synthesis Example 3 Comparative Synthesis Example 4 Comparative Synthesis Example 5 Comparative Synthesis Example 6 Comparative Synthesis Example 7 Comparative Synthesis Example 8 Comparative Synthesis Example 9 Comparative Synthesis Example 10 Comparative Synthesis Example 11 Modified conjugated diene polymers (Sample No.) 11 12 13 14 15 16 17 18 19 20 twenty one Aggregation conditions butadiene (g / minute) 30.8 30.8 30.8 30.8 30.8 30.8 1050 g - 30.8 30.8 30.8 styrene (g / minute) 0 0 0 0 0 0 0 g - 0 0 0 n-Hexane (g / minute) 189.3 189.3 189.3 189.3 189.3 189.3 4780 g - 189.3 189.3 189.3 Polymerization temperature (°C) 78 78 78 78 78 78 45→95 - 78 78 78 Processing n-butyllithium (mmol / min) 0.072 0.072 0.072 0.072 0.072 0.072 0 mmol - 0.072 0.072 0.072 Polymerization-initiated n-butyllithium (mmol / min) 0.205 0.205 0.205 0.205 0.361 0.205 10.66 mmol - 0.205 0.205 0.205 Amount of polar substances added (mmol / min) 0.027 0.027 0.027 0.027 0.048 0.027 0.01 mmol - 0.027 0.027 0.027 branching agent type - BS-1 BS-2 - BS-1 BS-4 BS-1 - BS-3 BS-1 BS-1 Added amount (mmol / min) - 0.030 0.060 - 0.053 0.017 1.33 mmol - 0.03 0.03 0.03 Modifier type - - - A A A A - A A A Added amount (mmol / min) - - - 0.155 0.272 0.155 6.40 mmol - 0.124 0.155 0.155 Analysis values (Physical Property 1) Munich viscosity before modification (100℃) 49 58 56 48 15 78 - 43 64 58 58 Modified conjugated diene polymers (Physical Property 1) Modified Munich viscosity (100℃) - - - 51 twenty four 83 46 - 75 65 69 (Physical Property 2) 1,2-Vinyl Bond Weight (mol%) 17 17 17 17 18 17 16 1 17 6 0 (Physical Property 3) Styrene content (quality%) 0 0 0 0 0 0 0 0 0 0 0 (Property 4) Glass transition temperature (°C) -89.6 -89.6 -89.6 -89.6 -88.8 -89.6 -90.1 -101.9 -89.6 -87.4 -81.2 (Physical Property 5) Branching Degree Bn per molecule - 1.4 1.1 - 1.3 5.6 1.2 - 4.4 1.7 1.7 (Physical Property 7) Modification Rate (quality%) - - - 77 86 80 71 - 76 81 81 (Physical Property 6) Weight Average Molecular Weight (10 4 g / mol) 41.6 44.5 43.8 42.2 33.6 52.4 40.3 - 49.2 46.0 46.0 (Physical Property 6) Number Average Molecular Weight (10 4 g / mol) 21.4 23.6 23.3 22.7 18.5 28.2 31.5 - 26.7 24.6 24.6 (Physical property 6)Mw / Mn 1.94 1.88 1.88 1.86 1.82 1.86 1.28 - 1.84 1.87 1.87 (Physical Property 8) Hydrogenation Rate 0 0 0 0 0 0 0 0 0 11.2 33.4 *Comparative Synthesis Example 8 uses high-cis BR BR150 manufactured by UBE Elastomer.

[0240] (Examples 1, 2 and Comparative Example 10) Samples 1 and 18 shown in Tables 1 and 2 were used as raw material rubbers, and rubber compositions containing each raw material rubber were obtained according to the composition shown in Table 3.

[0241] (Examples 1 and 2 and Comparative Example 10 of Carbon Blending and Mixing Methods) Rubber compositions were obtained by mixing the materials shown in Table 3 using the following method. Using a closed mixer (0.3 L capacity) equipped with a temperature control device, as the first stage of mixing, the raw rubber (samples 1 and 18), carbon black, (silicon dioxide, silane coupling agent), SRAE oil, zinc oxide, and stearic acid were mixed at a filler ratio of 65% and a rotor speed of 30–50 rpm. The temperature of the closed mixer was controlled at the discharge temperature of 155–160°C to obtain each rubber composition (blended compound).

[0242] Next, as the second stage of mixing, the obtained compound was cooled to room temperature, and an anti-aging agent was added. The compound was then mixed again to improve carbon black dispersion. During this process, the discharge temperature of the compound was adjusted to 155–160°C using the temperature control of the mixer. After cooling, as the third stage of mixing, sulfur and vulcanization accelerator 1 were added and mixed in an open drum set to 70°C. Subsequently, molding was performed, and vulcanization was carried out at 160°C using a vulcanization press for 30 minutes. The rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, the evaluation was conducted using the following method. The results are shown in Table 4.

[0243] (Comparative Examples 1 and 2) Using the sample 1 shown in Table 1 as the raw material rubber, a rubber composition containing the raw material rubber was obtained according to the composition shown in Table 3.

[0244] (Comparative Examples 1 and 2 of Silicon Dioxide Blending and Mixing Methods) A rubber composition was obtained by mixing the materials shown in Table 3 using the following method. Using a closed mixer (0.3 L capacity) equipped with a temperature control device, as the first stage of mixing, the raw material rubber (sample 1), (carbon black), silicon dioxide, silane coupling agent, SRAE oil, zinc oxide, and stearic acid were mixed at a filling rate of 65% and a rotor speed of 30–50 rpm. The temperature of the closed mixer was controlled at the discharge temperature of 155–160°C to obtain the rubber composition (blended material).

[0245] Subsequently, as the second stage of mixing, the obtained compound was cooled to room temperature, and an anti-aging agent was added. To improve the dispersion of silicon dioxide, the compound was mixed again. During this process, the discharge temperature of the compound was adjusted to 155–160°C using the temperature control of the mixer. After cooling, as the third stage of mixing, sulfur and vulcanization accelerators 2 and 3 were added and mixed in an open drum set to 70°C. Afterward, molding was performed, and vulcanization was carried out at 160°C using a vulcanization press for 20 minutes. The rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, the evaluation was conducted using the following method. The results are shown in Table 4.

[0246] (Evaluation 1) Cold Flow Performance: Samples 1 and 18 were cut from the package to sample dimensions L×W×H = 40 mm × 40 mm × 50 mm, and a 1 kg load was placed on each sample. The samples were then left to stand at 40°C for 24 hours. After 24 hours, the height (H) of the sample was measured, and the average retention rate of the two test points was calculated. The result of Comparative Example 10 was used as 100 and indexed. A larger index indicates better cold flow performance. The results are shown in Table 4.

[0247] (Evaluation 2) Munich Viscosity of the Formulation: The formulation obtained above, after the second stage of mixing and before the third stage of mixing, was used as a sample. Using a Munich viscometer, following ISO 289, after preheating at 130°C for 1 minute, the viscosity was measured after rotating the rotor at 2 revolutions per minute for 4 minutes. The result of Comparative Example 10 was indexed as 100. The smaller the index, the better the processability. The results are shown in Table 4.

[0248] (Evaluation 3) Sheet condition: The mixture obtained in the second stage of mixing and before the third stage of mixing was used as a sample. A 10-inch open roller with a temperature of 70°C was used to pass the rubber composition sheet through 3 times under the conditions of a guide width of 200 mm and a gap of 2.5 mm. The edge and surface condition of the rubber composition sheet were visually judged as follows. The results are shown in Table 4.

[0249] ◎: Smooth edges and surface; ○: Slightly rough edges but smooth surface; Δ: Roughness is greater at the edges, and roughness is visible on the surface; ×: Severe roughness at the edges and surface makes sheet forming difficult.

[0250] (Evaluation 4) Tensile strength was measured according to the tensile test method of JIS K6251. The result of Comparative Example 10 was indexed as 100. The larger the index, the better the tensile strength. The results are shown in Table 4.

[0251] (Evaluation 5) The Payne effect was measured using a viscoelastic testing machine "ARES" manufactured by Rheometric Scientific in torsion mode at a temperature of 50°C and a frequency of 10 Hz. The storage elastic modulus (G'0.1) was obtained at 0.1% strain, and the storage elastic modulus (G'10) was obtained at 10% strain. Based on the difference between the storage elastic modulus (G'0.1) and the storage elastic modulus (G'10), ΔG'(G'0.1-G'10) was calculated and defined as the Payne effect. The result of Comparative Example 10 was indexed as 100. The smaller the index, the better the dispersion of the filler. The results are shown in Table 4.

[0252] (Evaluation 6) Fuel efficiency was measured using a viscoelastic testing machine "ARES" manufactured by Rheometric Scientific in torsion mode at a temperature of 50°C, a frequency of 10Hz, and a strain of 3%. The tanδ value was used as an indicator of fuel efficiency, and the result of Comparative Example 10 was indexed to 100. The smaller the index, the better the fuel efficiency. The results are shown in Table 4.

[0253] (Evaluation 7) Abrasion resistance was measured using an Akron abrasion tester (manufactured by Yasuda Seiki Co., Ltd.) according to JIS K6264-2, under a load of 44.4 N and 1000 revolutions. The result of Comparative Example 10 was indexed as 100. The smaller the index, the better the abrasion resistance. The results are shown in Table 4.

[0254] (Evaluation 8) The dynamic amplification rate was determined using MTS ACUMEN3 according to JIS K6385. The static spring constant and dynamic spring constant of the crosslinked rubber composition were measured, and the dynamic amplification rate (dynamic spring constant / static spring constant) was calculated. The result of Comparative Example 10 was taken as 100 and exponentialized. The smaller the exponent, the better the vibration damping characteristics. The results are shown in Table 4.

[0255] [Table 3] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 10 rubber components (parts by weight) Conjugated diene polymers (sample 1) 50.0 50.0 50.0 50.0 - Conjugated diene polymers (sample 18) - - - - 50.0 Natural rubber (RSS#3) 50.0 50.0 50.0 50.0 50.0 Allocation conditions carbon black 50.0 40.0 - 25.0 50.0 Silicon dioxide - 10.0 50.0 25.0 - Silane dioxide coupling agent - 0.9 4.5 2.3 - Oil 10.0 10.0 10.0 10.0 10.0 Relative to 100 parts by weight of rubber component Number of parts by weight Zinc white 5.0 5.0 2.5 2.5 5.0 stearic acid 1.0 1.0 1.0 1.0 1.0 Anti-aging agents 2.0 2.0 2.0 2.0 2.0 sulfur 2.5 2.5 2.2 2.2 2.5 Sulfurization accelerator 1 1.5 1.5 - - 1.5 Sulfurization accelerator 2 - - 1.7 1.7 - Sulfurization accelerator 3 - - 2.0 2.0 - total 172.0 172.9 175.9 173.7 172.0 Carbon Black: "Seast KH (N550)" manufactured by Tokai Carbon; Silica: "Ultrasil 7000GR" manufactured by Evonik Degussa (Nitrogen adsorption specific surface area 170 m² / g); Silane Coupling Agent: "Si75" manufactured by Evonik Degussa; SRAE Oil (Bis(triethoxysilylpropyl)disulfide): "NC140" manufactured by JX Nippon Minerals & Energy Co., Ltd.; Anti-aging Agent: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine; Sulfation Accelerator 1: N-(tert-butyl)-2-benzothiazolylsulfenamide; Sulfation Accelerator 2: N-cyclohexyl-2-benzothiazolylsulfinamide; Sulfation Accelerator 3: Diphenylguanidine.

[0256] [Table 4] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 10 Conjugated diene polymer (Sample No.) 1 1 1 1 18 (Physical Property 1) Munich viscosity of modified conjugated diene polymer (100℃) 63 63 63 63 43 (Evaluation 1) Cold flow properties of modified conjugated diene polymers index 101 101 101 101 100 Allocation conditions CB 50 copies CB / Silicon Dioxide 40 servings / 10 servings Silicon dioxide 50 copies CB / Silicon Dioxide 25 servings / 25 servings CB 50 copies (Evaluation 2) Munich viscosity of the formulation (130℃) index 116 117 123 120 100 (Evaluation 3) Sheet condition Visual inspection ○ ○ Δ Δ Δ Physical property value (Evaluation 4) Tensile strength index 102 100 86 92 100 (Evaluation 5) The Payne Effect index 55 58 98 86 100 (Evaluation 6) Fuel efficiency index 65 67 93 87 100 (Evaluation 7) Abrasion resistance index 85 88 113 107 100 (Evaluation 8) Dynamic magnification index 81 85 99 95 100

[0257] As shown in Table 4, it can be confirmed that: compared with Comparative Examples 1 and 2 which are formulated with silicon dioxide, Examples 1 and 2 with carbon black have lower viscosity, better processability, better filler dispersion, and better tensile strength, fuel-saving rate, wear resistance and dynamic scale-up.

[0258] (Examples 3-11, Comparative Examples 3-13) Samples 2-21 shown in Tables 1 and 2 were used as raw material rubbers. The conjugated diene polymer sample 1 shown in Example 1 in Table 3 was changed to sample 2-21. Otherwise, rubber compositions containing each raw material rubber were obtained according to the formulation conditions and mixing method of Example 1.

[0259] The physical property evaluation was conducted according to (Evaluation 1) to (Evaluation 8) as described above, and the results are shown in Tables 5 and 6. Furthermore, the evaluations of Example 1 and Comparative Example 10 are also shown.

[0260] [Table 5] Example 1 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Conjugated diene polymer (Sample No.) 1 2 3 4 5 6 7 8 9 10 (Physical Property 1) Munich viscosity of modified conjugated diene polymer (100℃) 63 61 62 60 71 61 60 63 61 64 (Evaluation 1) Cold flow properties of modified conjugated diene polymers index 101 103 98 98 112 100 92 108 100 101 (Evaluation 2) Munich viscosity of the formulation (130℃) index 116 114 115 113 119 114 113 116 114 117 (Evaluation 3) Sheet condition Visual inspection ○ ○ ○ ○ ○ ○ ○ ◎ ○ ○ Physical property value (Evaluation 4) Tensile strength index 102 104 103 104 107 107 98 116 95 101 (Evaluation 5) The Payne Effect index 55 78 57 77 53 56 79 58 57 57 (Evaluation 6) Fuel efficiency index 65 73 66 75 63 68 77 68 65 66 (Evaluation 7) Abrasion resistance index 85 89 86 88 82 88 90 103 99 87 (Evaluation 8) Dynamic magnification index 81 86 82 86 85 86 88 93 88 85

[0261] [Table 6] Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Conjugated diene polymer (Sample No.) 11 12 13 14 15 16 17 18 19 20 twenty one (Physical Property 1) Munich viscosity of modified conjugated diene polymer (100℃) 49 58 56 51 twenty four 83 46 43 75 65 69 (Evaluation 1) Cold flow properties of modified conjugated diene polymers index 52 88 87 57 47 128 62 100 118 103 108 (Evaluation 2) Munich viscosity of the formulation (130℃) index 105 112 110 106 83 131 107 100 125 118 123 (Evaluation 3) Sheet condition Visual inspection ◎ ◎ ◎ ○ ◎ × Δ Δ Δ ○ Δ Physical property value (Evaluation 4) Tensile strength index 81 86 85 88 78 110 103 100 102 104 109 (Evaluation 5) The Payne Effect index 103 101 100 54 60 59 58 100 71 80 95 (Evaluation 6) Fuel efficiency index 103 100 97 65 62 67 63 100 74 75 92 (Evaluation 7) Abrasion resistance index 127 123 122 91 136 86 90 100 86 84 81 (Evaluation 8) Dynamic magnification index 107 103 103 81 74 87 82 100 90 92 112

[0262] As shown in Tables 5 and 6, it can be confirmed that: Compared with Comparative Examples 3 to 13, Examples 1 and 3 to 11 have excellent cold flow resistance, and the formulations have lower Munich viscosity when made into sulfurized products, exhibiting good processability. The Payne effect after being made into sulfurized products is lower, and the fuel consumption rate or tensile strength and dynamic amplification are excellent.

Claims

1. A rubber composition comprising, relative to 100 parts by mass of a rubber component containing at least one conjugated diene polymer, 10 parts by mass and 150 parts by mass of carbon black, wherein the content of a silica-based inorganic filler is 0% by mass or 30% by mass relative to the total amount of filler, and 10% by mass or more of the rubber component is a modified conjugated diene polymer, wherein the modified conjugated diene polymer (1) has a main chain branching structure having a branched structure in the main chain, (2) the main chain branching structure includes a structure derived from at least one conjugated diene monomer, or a structure derived from at least one conjugated diene monomer and a structure derived from an aromatic vinyl monomer, (3) having at least one end a terminal group having at least one carbonyl group and at least one substituted amino group in the molecule, (4) having a Munich viscosity of 30 to 120 measured at 100°C, and (5) having a branching degree (Bn) of 1.1 or more and less than 4.0 obtained by GPC-light scattering method using an attached viscosity detector. (6) The shape of the chromatogram measured by gel permeation chromatography (GPC) is unimodal, and the molecular weight distribution is 1.60 to 3.

00. (7) The hydrogenation rate is less than 10 mol; and the amount of 1,2-vinyl bonds in the conjugated diene units of the above-mentioned modified conjugated diene polymer is more than 10 mol% and less than 25 mol%.

2. The rubber composition of claim 1, wherein the amount of aromatic vinyl bonds in the modified conjugated diene polymer is more than 0% by mass and less than 10% by mass.

3. The rubber composition of claim 1, wherein the glass transition temperature (Tg) of the modified conjugated diene polymer is -110°C to -80°C.

4. The rubber composition of claim 1, wherein the modification rate of the modified conjugated diene polymer, as determined by column adsorption GPC, is 40% by mass or more.

5. The rubber composition of claim 1, wherein the hydrogenation rate of the modified conjugated diene polymer is less than 5 moles.

6. The rubber composition of claim 1, wherein the modified conjugated diene polymer has the structure shown in formula (1) and / or formula (2) below, [Chemical 1] (in formula (1), P represents a conjugated diene polymer containing at least one conjugated diene monomer, and Ra and Rb each independently represent a hydrocarbon group having 1 to 20 carbon atoms) [Chemical 2] (in formula (2), P represents a conjugated diene polymer containing at least one conjugated diene monomer, and Ra and Rb each independently represent a hydrocarbon group having 1 to 20 carbon atoms).

7. The rubber composition of claim 1, wherein the main chain branching structure of the modified conjugated diene polymer has a portion derived from an ethylene monomer comprising alkoxysilyl or halosilyl groups, and the branching structure is present in the portion derived from the ethylene monomer comprising alkoxysilyl or halosilyl groups.

8. The rubber composition of claim 7, wherein the portion of the ethylene monomer derived from the alkoxysilyl or halosilyl group is a monomer unit derived from the compound represented by formula (3) or formula (4) below, and the branch structure in the main chain branch structure of the modified conjugated diene polymer has a branch point of the polymer chain obtained from the monomer unit of the compound represented by formula (3) or formula (4) below, [Chemical 3] (wherein, R1 represents a hydrogen atom, or an alkyl group of 1 to 20 carbons or an aryl group of 6 to 20 carbons that may have a branch structure in a portion thereof, R2 to R3 each independently represent an alkyl group of 1 to 20 carbons or an aryl group of 6 to 20 carbons that may have a branch structure in a portion thereof, and when there are multiple R1 to R3, each is independent; X1 represents an independent halogen atom, m represents an integer of 0 to 2, n represents an integer of 0 to 3, l represents an integer of 0 to 3, and (m + n + l) is 3) [Chemical 4] (In the formula, R2 to R5 each independently represent a portion of an alkyl group with 1 to 20 carbon atoms or an aryl group with 6 to 20 carbon atoms that may have a branched structure. When there are multiple R2 to R5, each is independent. X2 to X3 represent independent halogen atoms. m represents an integer from 0 to 2, n represents an integer from 0 to 3, l represents an integer from 0 to 3, (m + n + l) is 3, a represents an integer from 0 to 2, b represents an integer from 0 to 3, c represents an integer from 0 to 3, (a + b + c) is 3).

9. The rubber composition of claim 8, wherein the main chain branching structure of the modified conjugated diene polymer has monomer units derived from the compound represented by formula (3) above, in formula (3) above, R1 represents a hydrogen atom and m represents 0.

10. The rubber composition of claim 8, wherein the main chain branching structure of the modified conjugated diene polymer has monomer units derived from the compound represented by formula (4) above, where m represents 0 and b represents 0.

11. The rubber composition of claim 8, wherein the main chain branching structure of the modified conjugated diene polymer has monomer units derived from the compound represented by formula (3) above, in formula (3) above, R1 represents a hydrogen atom, m represents 0, n represents 3, and l represents 0.

12. The rubber composition of claim 8, wherein the main chain branching structure of the modified conjugated diene polymer has monomer units derived from the compound represented by formula (4) above, in formula (4) m represents 0, n represents 3, l represents 0, a represents 0, b represents 0, and c represents 3.

13. A vulcanized rubber composition obtained by vulcanizing a rubber composition as claimed in any one of claims 1 to 12.