Conjugated diene polymer and rubber composition

Abstract

To provide a crosslinked rubber composition excellent in tensile strength or fuel-saving property, antivibration proof properties when composed into a vulcanite.SOLUTION: A crosslinked rubber composition containing 100 pts.mass of a rubber component that includes at least one type of a conjugated diene polymer, and 20 to 150 pts.mass of a filler, where the volume fraction φ (vol%) of the filler in the crosslinked rubber composition and the pain effect ΔG' (MPa) calculated from a viscoelastic test satisfy the following equation (A): ΔG'<0.34×φ-3.4 (A) (In equation (A), ΔG' represents the pain effect obtained as the difference in the storage modulus (G') measured at 0.1% and 10% strain under conditions of a temperature 50°C and a frequency 10 Hz in a torsion mode for the crosslinked rubber composition in the viscoelastic test. φ represents the volume fraction (vol%) of the filler in the crosslinked rubber composition.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a conjugated diene-based polymer and a rubber composition. [Background technology]

[0002] Rubber materials containing natural rubber, which has excellent vibration-proof properties such as compression set and dynamic magnification, have been proposed as anti-vibration rubber for automobiles, trains, and the like (see, for example, Patent Document 1).

[0003] However, recent rubber materials may have insufficient vibration-damping properties, and there is a problem that, in a cross-linked rubber product containing a filler such as carbon black or silica, if the filler is not sufficiently dispersible, the vibration-damping properties are not fully expressed.

[0004] On the other hand, there has been an increasing demand for improved fuel economy in automobiles, and this has led to demands for improvements in the rubber materials used in automobile tires, particularly in the tire treads that come into contact with the road surface.

[0005] In particular, tires for heavy loads used on large vehicles such as trucks and buses are required to have improved fuel efficiency with less energy loss in addition to the conventional properties such as high strength and wear resistance required to support heavy loads. Specifically, rubber materials used in tire treads for heavy loads are required to have high tensile strength and excellent fuel economy.

[0006] As rubber materials that meet the above-mentioned requirements, for example, modified conjugated diene polymers having hydroxyl groups at the ends of the polymer chains and compositions thereof, as well as a method for producing a conjugated diene polymer in which a hydrocarbyloxysilane compound is reacted with the ends of the polymer chains and then a specific compound such as a hydrocarbyloxysilane compound is further reacted therewith, and a composition thereof have been proposed (see, for example, Patent Documents 2 and 3).

[0007] However, there is an increasing demand for improved durability in tires for heavy loads, and crosslinked rubber compositions having improved fuel economy, wear resistance and tensile strength for use in tires for heavy loads are in demand. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2004-292679 A [Patent Document 2] JP 2017-171806 A [Patent Document 3] International Publication No. 03 / 046020 Brochure Summary of the Invention [Problem to be solved by the invention]

[0009] In view of this background, it is desirable to provide a crosslinked rubber composition that is excellent in vibration-proofing properties, fuel saving properties, and tensile strength, and from the viewpoint of vibration-proofing properties and fuel saving properties, it is possible to improve them by reducing the amount of filler in the crosslinked rubber composition. However, in that case, the reinforcing properties of the rubber material are sacrificed, and the tensile strength is reduced. In other words, these vibration-proofing properties, fuel saving properties, and tensile strength are in a mutually contradictory relationship, and there is a problem that it is difficult to achieve them all at the same time.

[0010] Therefore, an object of the present invention is to provide a crosslinked rubber composition containing a filler, which has excellent vibration-proofing properties, fuel saving properties and tensile strength all at the same time. [Means for solving the problem]

[0011] As a result of intensive research by the present inventors to solve the problems of the conventional techniques described above, they have found that a crosslinked rubber composition containing 20 parts by mass or more and 150 parts by mass or less of a filler per 100 parts by mass of a rubber component containing at least one type of conjugated diene-based polymer, in which the volume fraction φ (vol %) of the filler in the crosslinked rubber composition and the Payne effect ΔG' (MPa) calculated by a viscoelasticity test satisfy a specific formula, can achieve a high degree of tensile strength, fuel saving properties and vibration-proofing properties, and have completed the present invention. That is, the present invention is as follows.

[0012] [1] A crosslinked rubber composition comprising 20 parts by mass or more and 150 parts by mass or less of a filler relative to 100 parts by mass of a rubber component containing at least one conjugated diene polymer, A crosslinked rubber composition, wherein a volume fraction φ (vol %) of a filler in the crosslinked rubber composition and a Payne effect ΔG' (MPa) calculated by a viscoelasticity test satisfy the following formula (A): ΔG'<0.34×φ-3.4 (A) (In formula (A), ΔG' represents the Payne effect obtained as the difference in storage modulus (G') value when a crosslinked rubber composition is measured in a torsion mode at a temperature of 50°C and a frequency of 10 Hz at 0.1% strain and 10% strain, by a viscoelasticity test. φ represents the volume fraction (vol%) of the filler in the crosslinked rubber composition.) [2] The crosslinked rubber composition according to the above item [1], wherein the conjugated diene polymer is a conjugated diene polymer containing at least one type of conjugated diene monomer unit, the conjugated diene portion having a 1,2-vinyl bond content of 10 mol % or more and 25 mol % or less, a 1,4-cis bond content of 40 mol % or less, and a molecular weight distribution of 1.05 to 2.50. [3] The crosslinked rubber composition according to [1] or [2] above, wherein the conjugated diene polymer has a modification rate of 20 mass % or more. [4] The crosslinked rubber composition according to any one of [1] to [3] above, wherein the conjugated diene polymer has an amino group and an amide group structure represented by the following formula (I) and / or the following formula (II):

[0013] [ka]

[0014] In the formula (I), P represents a conjugated diene polymer containing at least one conjugated diene monomer; 1 and R 2 each independently represents a hydrocarbon group having 1 to 20 carbon atoms.

[0015] [ka]

[0016] In the formula (II), P represents a conjugated diene polymer containing at least one conjugated diene monomer; 1 and R 2 each independently represents a hydrocarbon group having 1 to 20 carbon atoms.

[0017] [5] The crosslinked rubber composition according to any one of [1] to [4], wherein the conjugated diene polymer has a branching degree (Bn) of 1.1 or more and less than 4.0, as measured by a GPC-light scattering method with a viscosity detector. [6] A vibration-proof rubber comprising the crosslinked rubber composition according to any one of [1] to [5] above. [7] A tire comprising the crosslinked rubber composition according to any one of [1] to [5]. [8] A shoe sole comprising the crosslinked rubber composition according to any one of [1] to [5] above. [9] A hose comprising the crosslinked rubber composition according to any one of [1] to [5].

[10] A sealing material comprising the crosslinked rubber composition according to any one of [1] to [5] above.

[11] A rubber roller comprising the crosslinked rubber composition according to any one of [1] to [5] above.

[12] A rubber roller comprising the crosslinked rubber composition according to any one of [1] to [5] above.

[13] A conveyor belt comprising the crosslinked rubber composition according to any one of [1] to [5] above. Effect of the Invention

[0018] According to the present invention, it is possible to provide a crosslinked rubber composition excellent in tensile strength, fuel saving properties and vibration damping properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The following describes in detail an embodiment of the present invention (hereinafter referred to as the "present embodiment"); however, the present invention is not limited to this embodiment, and various modifications are possible without departing from the gist of the present invention.

[0020] [Crosslinked Rubber Composition] The crosslinked rubber composition of the present embodiment is a crosslinked rubber composition that contains 20 parts by mass or more and 150 parts by mass or less of a filler per 100 parts by mass of a rubber component containing at least one type of conjugated diene-based polymer, and the volume fraction φ (vol %) of the filler in the crosslinked rubber composition and the Payne effect ΔG' (MPa) calculated by a viscoelasticity test satisfy the following formula (A). ΔG'< 0.34×φ-3.4 (A) (In formula (A), ΔG' represents the Payne effect obtained as the difference in storage modulus (G') value when a crosslinked rubber composition is measured in a torsion mode at a temperature of 50°C and a frequency of 10 Hz at 0.1% strain and 10% strain, by a viscoelasticity test. φ represents the volume fraction (vol%) of the filler in the crosslinked rubber composition.)

[0021] The crosslinked rubber composition of the present embodiment contains a rubber component and 20 parts by mass or more and 150 parts by mass or less of a filler (hereinafter, may be referred to as a "filler") per 100 parts by mass of the rubber component. From the viewpoint of improving fuel economy performance, processability, and abrasion resistance, the rubber component contains 10% by mass or more of at least one conjugated diene polymer described below based on the total amount (100% by mass) of the rubber component.

[0022] In the crosslinked rubber composition of this embodiment, a rubbery polymer other than the conjugated diene polymer described below (hereinafter simply referred to as a "rubbery polymer") can be used in combination with the conjugated diene polymer described below.

[0023] Such rubber-like polymers are not particularly limited, but examples thereof include conjugated diene polymers or hydrogenated products thereof, random copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, block copolymers of conjugated diene compounds and vinyl aromatic compounds or hydrogenated products thereof, non-diene polymers, and natural rubber.

[0024] Specific examples of rubber-like polymers include, but are not limited to, styrene-based elastomers such as butadiene rubber or hydrogenated products thereof, isoprene rubber or hydrogenated products thereof, styrene-butadiene rubber or hydrogenated products thereof, styrene-butadiene block copolymer or hydrogenated products thereof, and styrene-isoprene block copolymer or hydrogenated products thereof, and acrylonitrile-butadiene rubber or hydrogenated products thereof.

[0025] Examples of non-diene polymers include, but are not limited to, olefin elastomers such as ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, and ethylene-octene rubber; butyl rubber, brominated butyl rubber, acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α,β-unsaturated nitrile-acrylate-conjugated diene copolymer rubber, urethane rubber, and polysulfide rubber.

[0026] The natural rubber is not particularly limited, but examples thereof include smoked sheets such as RSS3 to 5, SMR, and epoxidized natural rubber.

[0027] The above-mentioned various rubber-like polymers may be modified rubbers to which a polar functional group such as a hydroxyl group, an amino group, etc. When used for tires, butadiene rubber, isoprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber are preferably used.

[0028] From the viewpoint of the balance between performance and processing characteristics, the weight average molecular weight of the rubber-like polymer is preferably 2000 to 2,000,000, more preferably 5000 to 1,500,000. Also, a low molecular weight rubber-like polymer, so-called liquid rubber, can be used. These rubber-like polymers may be used alone or in combination of two or more.

[0029] In the present embodiment, in the case of preparing a crosslinked rubber composition containing a conjugated diene polymer and a rubber-like polymer described later, the content ratio (mass ratio) of the conjugated diene polymer to the rubber-like polymer (conjugated diene polymer / rubber-like polymer) is preferably 10 / 90 or more and 100 / 0 or less, more preferably 20 / 80 or more and 90 / 10 or less, and even more preferably 50 / 50 or more and 80 / 20 or less.

[0030] Therefore, the rubber component contains, relative to the total amount (100 parts by mass) of the rubber component, preferably 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 90 parts by mass or less, and even more preferably 50 parts by mass or more and 80 parts by mass or less of the conjugated diene polymer.

[0031] When the content ratio of (conjugated diene polymer / rubber-like polymer) is within the above range, the crosslinked rubber composition has excellent abrasion resistance and tensile strength, and also has a satisfactory balance between fuel economy and wet skid resistance.

[0032] The filler contained in the crosslinked rubber composition of the present embodiment is not particularly limited, but examples thereof include silica-based inorganic fillers, carbon black, metal oxides, and metal hydroxides. Among these, carbon black or silica is preferred. The fillers may be used alone or in combination of two or more.

[0033] The content of the filler in the crosslinked rubber composition of this embodiment is 20 parts by mass or more and 150 parts by mass or less, preferably 25 parts by mass or more and 125 parts by mass or less, and more preferably 30 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the rubber component containing the above-mentioned conjugated diene-based polymer.

[0034] In the crosslinked rubber composition of the present embodiment, the content of the filler is 20 parts by mass or more per 100 parts by mass of the rubber component from the viewpoint of expressing the effect of adding the filler, and is 150 parts by mass or less per 100 parts by mass of the rubber component from the viewpoint of sufficiently dispersing the filler and making the processability and mechanical strength of the composition practically sufficient.

[0035] The silica-based inorganic filler is not particularly limited and may be any known one, but solid particles containing SiO2 or Si3Al as a structural unit are preferred, and solid particles containing SiO2 or Si3Al as a main component of the structural unit are more preferred. Here, the main component refers to a component contained in the silica-based inorganic filler in an amount of 50% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more.

[0036] Specific silica-based inorganic fillers are not particularly limited, but include inorganic fibrous materials such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. Also include silica-based inorganic fillers with hydrophobic surfaces, and mixtures of silica-based inorganic fillers and non-silica-based inorganic fillers. Among these, silica and glass fiber are preferred from the viewpoint of strength and abrasion resistance, and silica is more preferred. Examples of silica include dry silica, wet silica, and synthetic silicate silica. Among these silicas, wet silica is preferred from the viewpoint of excellent balance between the effect of improving fracture strength and wet skid resistance.

[0037] From the viewpoint of obtaining practically satisfactory abrasion resistance and breaking strength of the crosslinked rubber composition, the nitrogen adsorption specific surface area determined by the BET adsorption method of the silica-based inorganic filler is 100 m 2 / g or more 300m 2 / g or less, and 2 / g or more 250m 2 / g or less. If necessary, the specific surface area is relatively small (for example, the specific surface area is 200 m 2 / g or less) and silica-based inorganic fillers with a relatively large specific surface area (e.g., 200 m 2 In this embodiment, a silica-based inorganic filler having a relatively large specific surface area (for example, 200 m 2 In the case where a silica-based inorganic filler (having a silica content of 100% or more per 1000 g / g or more) is used, a crosslinked rubber composition containing a conjugated diene-based polymer described later tends to improve the dispersibility of silica, is particularly effective in improving abrasion resistance, and achieves a high level of balance between good tensile strength and fuel economy.

[0038] The content of the silica-based inorganic filler in the crosslinked rubber composition is preferably 20 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, relative to 100 parts by mass of the rubber component containing the conjugated diene polymer. In the rubber composition of the present embodiment, the content of the silica-based inorganic filler is 20 parts by mass or more relative to 100 parts by mass of the rubber component from the viewpoint of exhibiting the effect of adding the inorganic filler, and is 150 parts by mass or less relative to 100 parts by mass of the rubber component from the viewpoint of sufficiently dispersing the inorganic filler and making the processability and mechanical strength of the composition practically sufficient.

[0039] The carbon black is not particularly limited, but examples thereof include carbon blacks of various classes such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon blacks having a nitrogen adsorption specific surface area of ​​50 m 2 / g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or less is preferred.

[0040] In the crosslinked rubber composition of this embodiment, the content of carbon black is preferably 20 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, relative to 100 parts by mass of the rubber component containing the conjugated diene polymer. In the crosslinked rubber composition of this embodiment, the content of carbon black is preferably 20 parts by mass or more relative to 100 parts by mass of the rubber component from the viewpoint of expressing the performance required for industrial product applications, such as hardness and vibration-proofing properties, and is preferably 150 parts by mass or less relative to 100 parts by mass of the rubber component from the viewpoint of dispersibility.

[0041] Metal oxide refers to solid particles whose main component is a structural unit represented by the chemical formula MxOy (M represents a metal atom, and x and y each independently represent an integer of 1 to 6).

[0042] The metal oxide is not particularly limited, but examples thereof include alumina, titanium oxide, magnesium oxide, and zinc oxide.

[0043] The metal hydroxide is not particularly limited, but examples thereof include aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0044] The crosslinked rubber composition of the present embodiment may contain a silane coupling agent. The silane coupling agent has a function of strengthening the interaction between the rubber component and the inorganic filler, and has a group having affinity or binding properties for each of the rubber component and the silica-based inorganic filler, and is preferably a compound having a sulfur bond portion and an alkoxysilyl group or a silanol group portion in one molecule. Examples of such compounds include, but are not limited to, bis-[3-(triethoxysilyl)-propyl]-tetrasulfide, bis-[3-(triethoxysilyl)-propyl]-disulfide, and bis-[2-(triethoxysilyl)-ethyl]-tetrasulfide.

[0045] In the crosslinked rubber composition of the present embodiment, the content of the silane coupling agent is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and even more preferably 1.0 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the inorganic filler. When the content of the silane coupling agent is within the above range, the above-mentioned effect of the addition of the silane coupling agent tends to be more remarkable.

[0046] The crosslinked rubber composition of the present embodiment may contain a rubber softener from the viewpoint of improving its processability.

[0047] The amount of rubber softener added is expressed as the total amount including the amount of rubber softener previously contained in the above-mentioned conjugated diene polymer or other rubber-like polymers, and the amount of rubber softener added when preparing a crosslinked rubber composition, per 100 parts by mass of the rubber component containing the above-mentioned conjugated diene polymer.

[0048] As the rubber softener, mineral oil or a liquid or low molecular weight synthetic softener is preferable.

[0049] Mineral oil-based rubber softeners, called process oils or extender oils, which are used to soften rubber, increase its volume, and improve its processability, are mixtures of aromatic rings, naphthene rings, and paraffin chains, and those in which the carbon number of the paraffin chain is 50% or more of the total carbon are called paraffin-based, those in which the carbon number of the naphthene ring is 30% to 45% of the total carbon are called naphthene-based, and those in which the aromatic carbon number is more than 30% of the total carbon are called aromatic. When the conjugated diene polymer of the present embodiment is a copolymer of a conjugated diene compound and a vinyl aromatic compound, it is preferable to use a rubber softener having a moderate aromatic content, since it tends to be compatible with the copolymer.

[0050] In the crosslinked rubber composition of the present embodiment, the content of the rubber softener is preferably 0 to 100 parts by mass, more preferably 5 to 90 parts by mass, and even more preferably 10 to 80 parts by mass, per 100 parts by mass of the rubber component. By making the content of the rubber softener 100 parts by mass or less per 100 parts by mass of the rubber component, bleeding out is suppressed, and stickiness of the surface of the rubber composition tends to be suppressed.

[0051] The method for producing the crosslinked rubber composition of the present embodiment is not particularly limited, but examples thereof include a method of melt-kneading a conjugated diene polymer with other rubber-like polymers, silica-based inorganic fillers, carbon black and other fillers, additives such as silane coupling agents and rubber softeners using a general mixer such as an open roll, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method of dissolving and mixing each component and then removing the solvent by heating. Among these, the melt-kneading method using a roll, a Banbury mixer, a kneader, or an extruder is preferred from the viewpoint of productivity and good kneading. In addition, either a method of kneading a rubber component with other fillers, a silane coupling agent, and additives at once or a method of mixing them in several batches can be applied.

[0052] The crosslinked rubber composition of the present embodiment may be a crosslinked rubber composition vulcanized with a vulcanizing agent (hereinafter, sometimes referred to as a "vulcanized composition"). The vulcanizing agent is not particularly limited, but examples thereof include radical generators 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 polymer polysulfur compounds. In the rubber composition of the present embodiment, the content of the vulcanizing agent is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the rubber component. As the vulcanization method, a conventionally known method can be applied, and the vulcanization temperature is preferably 120°C or more and 200°C or less, and more preferably 140°C or more and 180°C or less.

[0053] In vulcanization, a vulcanization accelerator may be used as necessary. As the vulcanization accelerator, a conventionally known material may be used, and although not particularly limited, examples thereof include sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. Furthermore, although not particularly limited, examples of the vulcanization aid include zinc oxide and stearic acid. The content of the vulcanization accelerator is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the rubber component.

[0054] In the crosslinked rubber composition of the present embodiment, various additives such as softeners and fillers other than those described above, heat stabilizers, antistatic agents, weather stabilizers, antiaging agents, colorants, and lubricants may be used within the scope of the present invention. As the other softeners, known softeners can be used. As the other fillers, specific examples include, but are not limited to, calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. As the above-mentioned heat stabilizers, antistatic agents, weather stabilizers, antiaging agents, colorants, and lubricants, known materials can be used.

[0055] [Formula (A)] In the crosslinked rubber composition of the present embodiment, the volume fraction φ (vol %) of the filler in the crosslinked rubber composition and the Payne effect ΔG′ (MPa) calculated by a viscoelasticity test satisfy the following formula (A). ΔG'< 0.34×φ-3.4 (A) (In formula (A), ΔG' represents the Payne effect obtained as the difference in storage modulus (G') value when a crosslinked rubber composition is measured in a torsion mode at a temperature of 50°C and a frequency of 10 Hz at 0.1% strain and 10% strain, by a viscoelasticity test. φ represents the volume fraction (vol%) of the filler in the crosslinked rubber composition.)

[0056] The Payne effect is usually used to obtain information about the filler-filler interactions in a rubber matrix; the higher the storage modulus (G') value at small strains, the higher the filler-filler interactions. During the strain sweep measurements, the storage modulus value decreases due to the destruction of the filler network, resulting in similar G' values ​​at large strains, even though the filler-filler interactions start at small strains.

[0057] Here, the Payne effect (ΔG') and the storage modulus at small strain (G') vary not only depending on the dispersibility of the filler in the crosslinked rubber composition but also on the volume fraction (φ) of the filler, and the higher the volume fraction (φ) of the filler, the larger the value tends to be. For example, when the filler is a silica-based inorganic filler, the volume fraction (φ) of the filler in the crosslinked rubber composition can be measured by measuring the m ash content (the amount of components that remain unburned when the crosslinked rubber composition is burned), or by converting the weight fraction of the silica-based inorganic filler quantified by a known quantitative analysis method using fluorescent X-rays or a known ICP analysis method into a volume fraction.

[0058] The range of ΔG' is preferably ΔG'<0.33×φ-3.3, and more preferably ΔG'<0.32×φ-3.2. When ΔG′ is less than the above upper limit, the crosslinked rubber composition has a more dispersed filler, which is more preferable.

[0059] From the viewpoint of dispersibility of the filler, the lower limit of ΔG' is not particularly limited, but from the viewpoint of fully expressing the rigidity of the crosslinked rubber composition, 0.10×φ-1.0<ΔG' is preferable, 0.11×φ-1.1<ΔG' is more preferable, and 0.12×φ-1.2<ΔG' is even more preferable.

[0060] The Payne effect ΔG' calculated by a viscoelasticity test of a crosslinked rubber composition can be reduced by effectively causing the filler to interact with the rubber component, thereby reducing the interaction between the fillers. As a method for effectively causing the filler to interact with the rubber component in this way, for example, a method of compounding a modified conjugated diene polymer, as described below, can be mentioned.

[0061] The range of the volume fraction (φ) in the crosslinked rubber composition is not particularly limited as long as the content is within a range of 20 to 150 parts by mass per 100 parts by mass of the rubber component. From the viewpoint of ensuring practically applicable processability while fully exhibiting the reinforcing effect of the filler, the range is preferably 5.0 to 50 vol%, more preferably 6.0 to 45 vol%, and even more preferably 7.0 to 40 vol%.

[0062] [Conjugated diene polymer] The conjugated diene polymer of the present embodiment is preferably a conjugated diene polymer containing at least one type of conjugated diene monomer.

[0063] (Microstructure) The conjugated diene polymer of this embodiment preferably has a microstructure in which the amount of 1,2-vinyl bonds is specified to be 10 mol % or more and 25 mol % or less, and the amount of 1,4-cis bonds is specified to be 40 mol % or less.

[0064] The microstructure of the conjugated diene polymer can be measured by using a Fourier transform infrared spectrophotometer according to the method described in the examples below.

[0065] The 1,2-vinyl bond content of the conjugated diene polymer of this embodiment is preferably 10 mol % or more and 25 mol % or less, more preferably 11 mol % or more and 23 mol % or less, and even more preferably 12 mol % or more and 22 mol % or less.

[0066] In order to set the 1,2-vinyl bond amount within the above-mentioned specific range, it can be controlled by the amount of polar substance added in the polymerization step. When the amount of polar compound added is increased, the 1,2-vinyl bond amount increases and the polymerization reaction is also promoted, but when a composition containing a filler or the like is formed, the breaking strength and abrasion resistance tend to deteriorate, so it is necessary to adjust the amount of polar substance added to control the 1,2-vinyl bond amount within a specific range. More specifically, this will be described in the examples below.

[0067] The 1,4-cis bond content of the conjugated diene polymer of the present embodiment is preferably 40 mol % or less, more preferably 38 mol % or less, and even more preferably 36 mol % or less.

[0068] The amount of 1,4-cis bonds can be adjusted to the above-mentioned specific range by carrying out polymerization by living anionic polymerization reaction using an organic alkali metal or an organic alkaline earth metal as a polymerization initiator. This makes it possible to obtain a conjugated diene polymer having an active terminal, and then in a branching step using a branching agent described later, the branched structure can be appropriately controlled. Furthermore, by adding a nitrogen-containing modifier described later, a conjugated diene polymer with a high modification rate tends to be obtained, and when a composition containing a filler or the like is formed, a composition with a good balance between low hysteresis loss and wet skid resistance tends to be obtained.

[0069] (Molecular Weight and Molecular Weight Distribution) The conjugated diene polymer of the present embodiment has a number average molecular weight and a weight average molecular weight (hereinafter simply referred to as "number average molecular weight" and "weight average molecular weight") that are determined as polystyrene-equivalent molecular weights by gel permeation chromatography (hereinafter also referred to as "GPC") measurement, which is a relative comparison method with a standard polystyrene sample. 4 g / mol or more 100×10 4 g / mol or less is preferable, and 10×10 4 g / mol or more 50×10 4 g / mol or less is more preferable, and 20×10 4 g / mol or more 35×10 4 g / mol or less. 4 g / mol or more 200×10 4 g / mol or less is preferable, and 20×10 4 g / mol or more 125×10 4 g / mol or less is more preferable, and 30×10 4 g / mol or more 75×10 4 It is more preferably less than g / mol.

[0070] The conjugated diene polymer of this embodiment has a molecular weight distribution (Mw / Mn) expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 1.05 or more and 2.50 or less. A conjugated diene polymer having a molecular weight distribution in this range tends to have excellent abrasion resistance and breaking strength when the composition containing a filler or the like is vulcanized. The molecular weight distribution is more preferably 1.10 or more and 2.45 or less, even more preferably 1.15 or more and 2.40 or less, and even more preferably 1.20 or more and 2.35 or less.

[0071] The number average molecular weight, weight average molecular weight, and molecular weight distribution of the conjugated diene polymer can be measured by the method described in the Examples below. The number average molecular weight, weight average molecular weight, and molecular weight distribution of the conjugated diene polymer can be controlled to the above ranges, for example, by controlling the conditions such as temperature conditions in the polymerization step, or by adjusting the branching degree in the branching step. More specifically, this will be described in the production method of the conjugated diene polymer described below.

[0072] (denaturation rate) The conjugated diene polymer of the present embodiment preferably has a modification rate of 20% by mass or more. In this specification, the term "modification rate" is sometimes used, and the "modification rate" refers to the mass ratio of a conjugated diene polymer having a nitrogen atom-containing functional group to the total amount of the conjugated diene polymer.

[0073] The degree of modification can be measured by chromatography, which is capable of separating the functional group-containing modified and unmodified components.

[0074] Examples of methods using chromatography include a method in which a gel permeation chromatography column is used, packed with a polar substance such as silica that adsorbs specific functional groups, and the non-adsorbed components are quantified using an internal standard for comparison (column adsorption GPC method).

[0075] More specifically, the modification rate can be obtained by measuring the amount of a sample adsorbed to a silica column from the difference between a chromatogram measured using a polystyrene-based gel column and a chromatogram measured using a silica-based column, for a sample solution containing the sample and a low-molecular-weight internal standard polystyrene.

[0076] More specifically, the modification rate can be measured by the method described in the Examples.

[0077] In the conjugated diene polymer of the present embodiment, the modification rate can be controlled by adjusting the amount of the modifier added and the reaction method, and thus the modification rate can be controlled to 20 mass % or more.

[0078] The conjugated diene polymer of the present embodiment preferably has an amino group and an amide group represented by the following formula (I) and / or the following formula (II).

[0079] [ka]

[0080] In formula (I), P represents a conjugated diene polymer containing at least one conjugated diene monomer; 1 and R 2 each independently represents a hydrocarbon group having 1 to 20 carbon atoms.

[0081] [ka]

[0082] In formula (II), P represents a conjugated diene polymer containing at least one conjugated diene monomer; 1 and R 2 each independently represents a hydrocarbon group having 1 to 20 carbon atoms.

[0083] By having such terminal groups, when a rubber composition containing, in particular, carbon black as a filler is formed, the terminal groups interact or bond with the functional groups on the surface of the carbon black, tending to improve dispersion of the carbon black in the rubber composition, and the rubber composition becomes excellent in fuel economy and dynamic magnification when vulcanized.

[0084] (Branching degree (Bn)) From the viewpoints of processability, abrasion resistance and breaking strength, the conjugated diene polymer of this embodiment desirably has a branching degree (Bn) of 1.1 or more and less than 4.0 as measured by a GPC-light scattering method with a viscosity detector.

[0085] The degree of branching (Bn) being less than 4.0 means that the conjugated diene polymer of the present embodiment has substantially less than four polymer chains with a branched structure relative to the longest polymer main chain.

[0086] The branching degree (Bn) of a conjugated diene polymer is defined as g'=6Bn / {(Bn+1)(Bn+2)}, using the shrinkage factor (g') measured by GPC-light scattering method with a viscometer.

[0087] In general, a polymer having branches tends to have a smaller molecular size when compared to a linear polymer having the same absolute molecular weight.

[0088] The shrinkage factor (g') is a measure of the ratio of the molecular size to that of a linear polymer of the same assumed absolute molecular weight. In other words, the greater the degree of branching of a polymer, the smaller the shrinkage factor (g') tends to be.

[0089] In this embodiment, the intrinsic viscosity is used as an index of molecular size for this shrinkage factor. For linear polymers, the intrinsic viscosity [η] is −3.883M 0.771 In the above formula, M is the absolute molecular weight.

[0090] However, the shrinkage factor represents the rate of reduction in molecular size and does not accurately represent the branched structure of a polymer.

[0091] Therefore, the branching degree (Bn) of the conjugated diene polymer is calculated using the value of the shrinkage factor (g') at each absolute molecular weight of the conjugated diene polymer. The calculated "branching degree (Bn)" accurately represents the number of polymers that are directly or indirectly bonded to each other with respect to the longest main chain structure.

[0092] The calculated branching degree (Bn) is an index that expresses the branching structure of a conjugated diene polymer. For example, in the case of a typical four-branched star polymer (four polymer chains connected to the center), two polymer chain arms are bonded to the longest highly branched main chain structure, and the branching degree (Bn) is evaluated as 2.

[0093] In a typical six-branched star polymer, four polymer chain arms are attached to the longest highly branched main chain structure, and the branching degree (Bn) is evaluated as four.

[0094] The conjugated diene polymer of the present embodiment desirably has a degree of branching (Bn) of 1.1 or more and less than 4.0. In such a case, it means that the conjugated diene polymer has a star polymer structure having a branch similar to that of a linear star polymer structure with less than 6 branches.

[0095] Here, "branch" refers to a structure formed by direct or indirect bonding of one polymer to another polymer, and "degree of branching (Bn)" refers to the number of polymers that are directly or indirectly bonded to each other in the longest main chain structure.

[0096] By having a branching degree (Bn) of 1.1 or more and less than 4.0, the conjugated diene-based polymer of the present embodiment has good interactivity with a filler while suppressing the cold flow of a bale, which is a product form of the conjugated diene copolymer, and tends to have excellent fuel economy and dynamic magnification when vulcanized.

[0097] The degree of branching (Bn) of the conjugated diene polymer of the present embodiment is 1.1 or more and less than 4.0, preferably 1.2 or more and less than 3.9, more preferably 1.3 or more and less than 3.8, and even more preferably 1.4 or more and less than 3.7. A conjugated diene polymer having a degree of branching (Bn) within this range tends to be excellent in fuel saving properties and dynamic magnification when vulcanized.

[0098] The degree of branching of the conjugated diene polymer can be controlled to 1.1 or more and less than 4.0 by combining the amount of the branching agent and the amount of the terminal modifier. Specifically, the degree of branching can be controlled by the number of functional groups of the branching agent, the amount of the branching agent added, the timing of adding the branching agent, and the number of functional groups and the amount of the nitrogen atom-containing modifier added. More specifically, this will be described later in the method for producing the conjugated diene polymer.

[0099] (Mooney viscosity) The conjugated diene polymer of the present embodiment has a Mooney viscosity measured at 100° C. 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, from the viewpoints of productivity of the conjugated diene polymer, processability when the composition is made into a composition containing a filler or the like, and abrasion resistance and breaking strength when the composition is made into a vulcanizate.

[0100] When the Mooney viscosity measured at 100°C is 30 or more, the abrasion resistance and breaking strength of the vulcanized product are improved, and when the Mooney viscosity measured at 100°C is 120 or less, problems in the production of the conjugated diene polymer are suppressed, and the processability is improved when the polymer is made into a composition containing a filler or the like.

[0101] The Mooney viscosity is measured by using a sample of a conjugated diene polymer formed into a plate shape by a pressure press, setting it in the apparatus, preheating the sample at 100°C for 1 minute, rotating the rotor at 2 rpm, measuring the torque after 4 minutes, and taking the measured value as the Mooney viscosity (ML(1+4)). More specifically, it can be measured by the method described in the Examples below. The Mooney viscosity of the conjugated diene polymer can be controlled to the above range, for example, by controlling the conditions such as the temperature conditions in the polymerization step or by adjusting the degree of branching in the branching step. More specifically, it will be described in the method for producing a conjugated diene polymer described below.

[0102] (Aromatic vinyl compounds) The conjugated diene polymer of the present embodiment contains at least one conjugated diene monomer and may also contain an aromatic vinyl compound.

[0103] Examples of aromatic vinyl compounds include, but are not limited to, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o,p-dimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.

[0104] The content of the aromatic vinyl compound in the conjugated diene polymer of the present embodiment can be controlled by adjusting the amount of aromatic vinyl monomer added and the polymerization time in the polymerization step in the production method for the conjugated diene polymer described below.

[0105] [Method for producing conjugated diene polymer] The method for producing a conjugated diene polymer according to the present embodiment is a method for producing the above-mentioned conjugated diene polymer, and includes a polymerization and branching step of polymerizing a conjugated diene compound using an organolithium compound as a polymerization initiator while adding a branching agent as necessary to obtain a conjugated diene polymer having a branched structure, and a modification step of modifying the conjugated diene polymer with a modifying agent as necessary.

[0106] (Polymerization and branching process) The polymerization and branching step in the method for producing a conjugated diene polymer of the present embodiment (hereinafter also simply referred to as the "polymerization and branching step") is, for example, a step of using an organic monolithium compound as a polymerization initiator, polymerizing at least one conjugated diene compound, and adding a branching agent as necessary to obtain a conjugated diene polymer having a branched structure. Hereinafter, when describing the polymerization reaction in the polymerization and branching step, it is also referred to as the "polymerization step", and when describing the reaction with the branching agent, it is also referred to as the "branching step".

[0107] In the polymerization step, it is preferable to carry out polymerization by a propagation reaction by a living anionic polymerization reaction, which can obtain a conjugated diene-based polymer having an active terminal. Then, in the branching step using a branching agent, the main chain branching can be appropriately controlled, and a conjugated diene-based polymer having a high modification rate can be obtained.

[0108] The conjugated diene polymer may be a homopolymer obtained using a single conjugated diene compound as a monomer, or a polymer, i.e., a copolymer, obtained using different kinds of conjugated diene compounds as monomers.

[0109] Specific examples of the conjugated diene compound include, but are not limited to, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-hexadiene, and 1,3-heptadiene. Among these, 1,3-butadiene and isoprene are preferred from the viewpoint of industrial availability. These may be used alone or in combination of two or more.

[0110] <Polymerization initiator> As the polymerization initiator, at least an organic monolithium compound can be used. The organomonolithium compound is not particularly limited, but examples thereof include low molecular weight compounds and solubilized oligomeric organomonolithium compounds. In addition, examples of the organomonolithium compound include compounds having a carbon-lithium bond, a nitrogen-lithium bond, and a tin-lithium bond in terms of the bonding mode between the organic group and the lithium. The amount of the organic monolithium compound used as the polymerization initiator is preferably determined depending on the targeted molecular weight of the conjugated diene polymer. The amount of a monomer such as a conjugated diene compound used relative to the amount of a polymerization initiator used is related to the degree of polymerization, that is, tends to be related to the number average molecular weight and / or weight average molecular weight. Therefore, in order to increase the molecular weight, the amount of the polymerization initiator used should be adjusted to decrease, and in order to decrease the molecular weight, the amount of the polymerization initiator used should be adjusted to increase.

[0111] The organomonolithium compound is preferably an alkyllithium compound having a substituted amino group or a dialkylaminolithium compound, from the viewpoint that it is used as one method for introducing nitrogen atoms into a conjugated diene-based polymer.

[0112] In this case, a conjugated diene polymer having a nitrogen atom consisting of an amino group at the polymerization initiation terminal is obtained.

[0113] The substituted amino group is an amino group that does not have an active hydrogen or has a structure in which the active hydrogen is protected.

[0114] Examples of alkyllithium compounds having an amino group that does not have an active hydrogen include, but are not limited to, 3-dimethylaminopropyllithium, 3-diethylaminopropyllithium, 4-(methylpropylamino)butyllithium, and 4-hexamethyleneiminobutyllithium.

[0115] The alkyllithium compound having an amino group with an active hydrogen protected structure is not particularly limited, but examples thereof include 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0116] Examples of dialkylaminolithium include, but are not limited to, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, lithium-di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.

[0117] These organomonolithium compounds having a substituted amino group can also be used as solubilized oligomeric organomonolithium compounds by reacting them with a small amount of a polymerizable monomer, such as 1,3-butadiene, isoprene, or styrene.

[0118] As the organomonolithium compound, from the viewpoints of industrial availability and ease of control of the polymerization reaction, an alkyllithium compound is preferred. In this case, a conjugated diene-based polymer having an alkyl group at the polymerization initiation terminal is obtained.

[0119] Examples of alkyllithium compounds include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium.

[0120] As the alkyllithium compound, n-butyllithium and sec-butyllithium are preferred from the viewpoints of industrial availability and ease of control of the polymerization reaction.

[0121] These organomonolithium compounds may be used alone or in combination of two or more, and may also be used in combination with other organometallic compounds.

[0122] Examples of other organometallic compounds include alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds.

[0123] Examples of alkaline earth metal compounds include, but are not limited to, organomagnesium compounds, organocalcium compounds, and organostrontium compounds, as well as alkaline earth metal alkoxides, sulfonates, carbonates, and amides.

[0124] Examples of organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Other organometallic compounds include organoaluminum compounds.

[0125] In the polymerization step, the polymerization reaction mode is not particularly limited, but examples thereof include a batchwise polymerization mode (also called a "batch type") and a continuous polymerization mode.

[0126] In the continuous system, one or more connected reactors can be used. The continuous reactor is, for example, a tank type or a tube type equipped with an agitator. In the continuous system, preferably, the monomer, the inert solvent, and the polymerization initiator are continuously fed into the reactor, a polymer solution containing a polymer is obtained in the reactor, and the polymer solution is continuously discharged.

[0127] The batch reactor may be, for example, a tank-type reactor equipped with a stirrer. In the batch reactor, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, a monomer is added continuously or intermittently during polymerization to obtain a polymer solution in the reactor, and the polymer solution is discharged after the polymerization is completed.

[0128] The polymerization step of the conjugated diene polymer is preferably carried out in an inert solvent. The solvent is not particularly limited, but examples thereof include hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents are not particularly limited, but examples thereof 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 consisting of mixtures thereof.

[0129] By treating the impurities, that is, allenes and acetylenes, with an organometallic compound before subjecting the polymer to the polymerization reaction, a conjugated diene-based polymer having a high concentration of active ends tends to be obtained, which is preferable since a modified conjugated diene-based polymer having a high modification rate tends to be obtained.

[0130] In the polymerization step, a polar compound may be added. It tends to be used as a vinylating agent for controlling the amount of 1,2 vinyl bonds in the conjugated diene polymer. It also tends to be effective in promoting the polymerization reaction.

[0131] The polar compound is not particularly limited, but examples of the polar compound that can be used include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium amylate; and phosphine compounds such as triphenylphosphine. These polar compounds may be used alone or in combination of two or more.

[0132] The amount of the polar compound used is not particularly limited and can be selected depending on the purpose, but is preferably 0.01 moles or more and 100 moles or less per mole of the polymerization initiator. Such polar compounds (vinylating agents) can be used as regulators for the microstructure of the conjugated diene polymer in an appropriate amount depending on the desired amount of 1,2-vinyl bonds.

[0133] The polymerization temperature in the polymerization step is preferably a temperature at which living anionic polymerization proceeds, and from the viewpoint of productivity, is more preferably 0°C or higher, and even more preferably 120°C or lower. By being in such a range, there is a tendency that the amount of the modifying agent reacting with the active terminal after the polymerization is completed can be sufficiently ensured. Even more preferably, it is 50°C or higher and 100°C or lower.

[0134] (Branching Agent) In the conjugated diene polymer of the present embodiment, when constructing a branched structure, a branching agent represented by the following formula (1) or formula (2) can be used as a branching agent.

[0135] [ka]

[0136] In the formula (1), R 1 R represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a branched structure in a portion thereof, or an aryl group having 6 to 20 carbon atoms. 2 ~R 3 R each independently represents an alkyl group having 1 to 20 carbon atoms, which may have a branched structure in a portion thereof, or an aryl group having 6 to 20 carbon atoms. 1 ~R 3 are each independent. X 1 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.

[0137] [ka]

[0138] In the formula (2), R 2 ~R 5 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms which may have a branched structure in a portion thereof, and when a plurality of R 2 ~R 5 are each independent. X 2 ~X 3 each independently represents a 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. a represents an integer of 0 to 2, b represents an integer of 0 to 3, c represents an integer of 0 to 3, and (a+b+c) is 3.

[0139] The branching agent represented by formula (1) is not particularly limited, but examples thereof 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, nylphenyl)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, diethoxymethyl(3-vinylphenyl)silane, dipropoxymethyl(3-vinylphenyl)silane, dibutoxymethyl(3-vinylphenyl)silane, diisopropoxymethyl(3-vinylphenyl)silane, dimethoxymethyl(2-vinylphenyl)silane, diethoxymethyl(2-vinylphenyl)silane, dipropoxymethyl(2-vinylphenyl)silane, and dibutoxymethyl(2-vinylphenyl)silane.

[0140] Also, 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, 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.

[0141] In addition, trimethoxy(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, di Isopropoxymethyl(4-isopropenylphenyl)silane, dimethoxymethyl(3-isopropenylphenyl)silane, diethoxymethyl(3-isopropenylphenyl)silane, dipropoxymethyl(3-isopropenylphenyl)silane, dibutoxymethyl(3-isopropenylphenyl)silane, diisopropoxymethyl(3-isopropenylphenyl)silane, dimethoxymethyl(2-isopropenylphenyl)silane, diethoxymethyl(2-isopropenylphenyl)silane, dipropoxymethyl(2-isopropenylphenyl)silane 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 propenylphenyl)silane, dimethylpropoxy(3-isopropenylphenyl)silane, dimethylbutoxy(3-isopropenylphenyl)silane, dimethylisopropoxy(3-isopropenylphenyl)silane, dimethylmethoxy(2-isopropenylphenyl)silane, dimethylethoxy(2-isopropenylphenyl)silane, dimethylpropoxy(2-isopropenylphenyl)silane, dimethylbutoxy(2-isopropenylphenyl)silane, and dimethylisopropoxy(2-isopropenylphenyl)silane.

[0142] Further examples thereof include 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.

[0143] 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 preferred, and trimethoxy(4-vinylphenyl)silane, triethoxy(4-vinylphenyl)silane, tripropoxy(4-vinylphenyl)silane, and tributoxy(4-vinylphenyl)silane, triisopropoxy(4-vinylphenyl)silane are more preferred.

[0144] The branching agent represented by the formula (2) is not particularly limited, and examples thereof 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-tripoxysilylphenyl)ethylene, 1,1-bis(3-tripentoxysilylphenyl)ethylene, 1,1-bis(3-triisopropoxysilylphenyl)ethylene, 1,1-bis(2-triisopropoxysilylphenyl)ethylene, 1,1-bis(3 ... methoxysilylphenyl)ethylene, 1,1-bis(2-triethoxysilylphenyl)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-(dipropylmethoxysilyl)phenyl)ethylene, 1,1-bis(4-(dimethylethoxysilyl)phenyl)ethylene, 1,1-bis(4-(diethylethoxysilyl)phenyl)ethylene, and 1,1-bis(4-(dipropylethoxysilyl)phenyl)ethylene.

[0145] 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 more preferred.

[0146] In the method for producing a conjugated diene-based polymer of the present embodiment, the amount of the branching agent added in the branching step for forming a branched structure is not particularly limited and can be selected depending on the purpose, etc., but is preferably 0.02 mol or more and 0.5 mol or less, 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, relative to 1 mol of the polymerization initiator.

[0147] The branching agent can be used in an appropriate amount according to the desired number of branching points as branching points of the branched structure of the conjugated diene portion of the conjugated diene polymer.

[0148] In the branching step, the timing of adding the branching agent is not particularly limited and can be selected depending on the purpose, etc., but from the viewpoint of improving the absolute molecular weight and the modification rate of the conjugated diene-based polymer, the timing is preferably when the raw material conversion rate after addition of the polymerization initiator is 20% or more, more preferably 40% or more, even more preferably 50% or more, even more preferably 65% ​​or more, and even more preferably 75% or more. After the branching agent is added, the desired raw materials may be further added to continue the polymerization step after branching, or the above-described process may be repeated.

[0149] The conjugated diene polymer of the present embodiment is not particularly limited, and may be a polymer of a conjugated diene monomer and a branching agent, or may be a copolymer of a conjugated diene monomer, a branching agent, and a monomer other than these. For example, when the conjugated diene monomer is butadiene or isoprene and is polymerized with a branching agent containing a vinyl aromatic moiety, the polymer chain is a so-called polybutadiene or polyisoprene, and the branched portion contains a structure derived from a vinyl aromatic. By having such a structure, the linearity per polymer chain is improved, and the crosslink density after vulcanization can be improved, thereby improving the wear resistance. Therefore, the conjugated diene polymer of the present embodiment is suitable for applications such as tires, resin modification, interior and exterior parts of automobiles, anti-vibration rubber, and footwear.

[0150] When the conjugated diene polymer is used for the tread of a tire carrying a high load, a copolymer of a conjugated diene monomer and a branching agent is preferred.

[0151] (Denaturation process) The method for producing a conjugated diene polymer of the present embodiment includes a modification step (hereinafter also simply referred to as the "modification step") of modifying the conjugated diene polymer obtained through the above-mentioned polymerization and branching steps with a modifying agent having a nitrogen-containing group. In the modification step, one active end of the conjugated diene polymer is modified with a modifying agent having a nitrogen-containing group to obtain a conjugated diene polymer.

[0152] The reaction temperature in the modification step is preferably the same as the polymerization temperature of the conjugated diene polymer, more preferably 0°C or higher and 120°C or lower, and even more preferably 50°C or higher and 100°C or lower.

[0153] The reaction time in the modification step is preferably 10 seconds or more, more preferably 30 seconds or more.

[0154] The mixing in the modification step may be carried out by any of mechanical stirring, stirring with a static mixer, and the like.

[0155] When the polymerization step is continuous, it is preferred that the modification step is also continuous.

[0156] The reactor used in the modification step may be, for example, a tank type or a tube type equipped with a stirrer. The modifying agent may be diluted with an inert solvent and continuously fed to the reactor. When the polymerization process is a batch process, the modifying agent may be directly charged into the polymerization reactor, or may be transferred to a separate reactor for the modification process.

[0157] The time from the polymerization step to the modification step is preferably short, preferably within 10 minutes, more preferably within 5 minutes, in which case a conjugated diene polymer with high modification efficiency tends to be obtained.

[0158] The time from the polymerization step to the modification step refers to, for example, the time from when the polymerization temperature reaches its peak temperature until the modifier is added when the polymerization step is a batch process, and refers to the time from when the modifier is added to the solution containing the conjugated diene-based polymer that has left the polymerization reactor when the polymerization step is a continuous process.

[0159] <Modifier> The nitrogen atom-containing modifying agent is not particularly limited, but examples thereof include isocyanate compounds, isothiocyanate compounds, isocyanuric acid derivatives, nitrogen atom group-containing carbonyl compounds, nitrogen atom group-containing vinyl compounds, and nitrogen atom group-containing epoxy compounds.

[0160] The isocyanate compound which is a modifying agent having a nitrogen atom-containing group is not particularly limited, but examples thereof include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate (C-MDI), phenyl isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, butyl isocyanate, and 1,3,5-benzene triisocyanate.

[0161] The isothiocyanate compound, which is a modifying agent having a nitrogen atom-containing group, is not particularly limited, and examples thereof include butyl isothiocyanate, cyclohexyl isothiocyanate, phenyl isothiocyanate, 2-chlorophenyl isothiocyanate, benzyl isothiocyanate, 2,6-diisopropylphenyl isothiocyanate, and 1,4-phenylene diisothiocyanate.

[0162] The isocyanuric acid derivative, which is a modifying agent having a nitrogen atom-containing group, is not particularly limited, and examples thereof include 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 1,3,5-tris(3-triethoxysilylpropyl)isocyanurate, 1,3,5-tri(oxiran-2-yl)-1,3,5-triazinane-2,4,6-trione, 1,3,5-tris(isocyanatomethyl)-1,3,5-triazinane-2,4,6-trione, and 1,3,5-trivinyl-1,3,5-triazinane-2,4,6-trione.

[0163] The nitrogen atom-containing carbonyl compound, which is a modifying agent having a nitrogen atom-containing group, is not particularly limited, and examples thereof include 1,3-dimethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 1-methyl-3-(2-methoxyethyl)-2-imidazolidinone, N-methyl-2-pyrrolidone, N-methyl-2-piperidone, N-methyl-2-quinolone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, and the like. Examples of the pyridine derivative include non-, methyl-2-pyridyl ketone, methyl-4-pyridyl ketone, propyl-2-pyridyl ketone, di-4-pyridyl ketone, 2-benzoylpyridine, N,N,N',N'-tetramethylurea, N,N-dimethyl-N',N'-diphenylurea, N,N-diethylmethylcarbamate, N,N-diethylacetamide, N,N-dimethyl-N',N'-dimethylaminoacetamide, N,N-dimethylpicolinic acid amide, and N,N-dimethylisonicotinic acid amide.

[0164] The vinyl compound which is a modifying agent having a nitrogen atom-containing group is not particularly limited, but examples thereof include N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N-methylmaleimide, N-methylphthalimide, N,N-bistrimethylsilylacrylamide, morpholinoacrylamide, 3-(2-dimethylaminoethyl)styrene, (dimethylamino)dimethyl-4-vinylphenylsilane, 4,4'-vinylidenebis(N,N-dimethylaniline), 4,4'-vinylidenebis(N,N-diethylaniline), 1,1-bis(4-morpholinophenyl)ethylene, 1-phenyl-1-(4-N,N-dimethylaminophenyl)ethylene, and the like.

[0165] The epoxy compound, which is a modifier having a nitrogen atom-containing group, is not particularly limited, but may be, for example, an epoxy group-containing hydrocarbon compound bonded to an amino group, and may further have an epoxy group bonded to an ether group. Such an epoxy compound is, for example, but is not limited to, an epoxy compound represented by the general formula (i).

[0166] [ka]

[0167] In the formula (i), R represents a divalent or higher organic group having at least one polar group selected from a divalent or higher hydrocarbon group, a polar group having oxygen such as ether, epoxy, or ketone, a polar group having sulfur such as thioether or thioketone, and a polar group having nitrogen such as a tertiary amino group or imino group.

[0168] The divalent or higher hydrocarbon group is a saturated or unsaturated, linear, branched or cyclic hydrocarbon group, and includes an alkylene group, an alkenylene group, a phenylene group, etc. A hydrocarbon group having 1 to 20 carbon atoms is preferable. Examples thereof include methylene, ethylene, butylene, cyclohexylene, 1,3-bis(methylene)-cyclohexane, 1,3-bis(ethylene)-cyclohexane, o-, m-, p-phenylene, m-, p-xylene, and bis(phenylene)-methane.

[0169] In the formula (i), R 1 and R 4 each represents a hydrocarbon group having 1 to 10 carbon atoms, and R 1 and R 4 may be the same or different from each other.

[0170] In the formula (i), R 2 and R 5 each represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms; R 2 and R 5 may be the same or different from each other.

[0171] In the formula (i), R 3 represents a hydrocarbon group having 1 to 10 carbon atoms, or a structure represented by the following formula (ii):

[0172] R 1 , R 2 , and R 3 may be bonded to each other to form a cyclic structure.

[0173] Also, R 3 When R represents a hydrocarbon group, R may be bonded to R to form a cyclic structure. 3 The N bonded to R may be directly bonded to the N bonded to R.

[0174] In the formula (i), n represents an integer of 1 or more, and m represents 0 or an integer of 1 or more.

[0175] [ka]

[0176] In the formula (ii), R 1 and R 2 is R in formula (i) 1 and R 2 is defined similarly to R 1 and R 2 may be the same or different from each other.

[0177] The epoxy compound, which is a modifying agent having a nitrogen atom-containing group, is preferably one having an epoxy group-containing hydrocarbon group, more preferably one having a glycidyl group-containing hydrocarbon group.

[0178] The epoxy group-containing hydrocarbon group bonded to the amino group or ether group is not particularly limited, but examples thereof include a glycidylamino group, a diglycidylamino group, and a glycidoxy group. More preferred molecular structures are epoxy group-containing compounds each having a glycidylamino group or a diglycidylamino group, and a glycidoxy group, and examples thereof include compounds represented by the following general formula (iii).

[0179] [ka]

[0180] In the formula (iii), R is defined as R in the formula (i), 6 represents a hydrocarbon group having 1 to 10 carbon atoms or a structure represented by the following formula (iv):

[0181] R 6 When represents a hydrocarbon group, it may be bonded to R to form a cyclic structure, in which case, R 6 The N bonded to R may be directly bonded to the N bonded to R. In formula (iii), n represents an integer of 1 or more, and m represents 0 or an integer of 1 or more.

[0182] [ka]

[0183] As the epoxy compound which is a modifying agent having a nitrogen atom-containing group, a compound having one or more diglycidylamino groups and one or more glycidoxy groups in the molecule is particularly preferred.

[0184] Specific examples of epoxy compounds used as a modifying agent having a nitrogen atom-containing group include N,N-diglycidyl-4-glycidoxyaniline, 1-N,N-diglycidylaminomethyl-4-glycidoxy-cyclohexane, 4-(4-glycidoxyphenyl)-(N,N-diglycidyl)aniline, 4-(4-glycidoxyphenoxy)-(N,N-diglycidyl)aniline, 4-(4-glycidoxybenzyl)-(N,N-diglycidyl)aniline, 4-(N,N'-diglycidyl-2-piperazinyl)-glycidoxybenzene, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-xylylenediamine. amine, 4,4-methylene-bis(N,N-diglycidylaniline), 1,4-bis(N,N-diglycidylamino)cyclohexane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, 4,4'-bis(diglycidylamino)benzophenone, 4-(4-glycidylpiperazinyl)-(N,N-diglycidyl)aniline, 2-[2-(N,N-diglycidylamino)ethyl]-1-glycidylpyrrolidine, N,N-diglycidylaniline, 4,4'-diglycidyl-dibenzylmethylamine, N,N-diglycidylaniline, N,N-diglycidylorthotoluidine, and N,N-diglycidylaminomethylcyclohexane. Of these, preferred ones include N,N-diglycidyl-4-glycidoxyaniline and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0185] The modifying agent having a nitrogen atom-containing group is also preferably an amine compound having no active hydrogen, and examples thereof include a tertiary amine compound, a protected amine compound in which the above-mentioned active hydrogen is replaced with a protecting group, an imine compound represented by the general formula -N=C (a compound represented by the general formula (D) described later), and an alkoxysilane compound bonded to a nitrogen atom-containing group.

[0186] As a modifying agent having a nitrogen atom-containing group and a protected amine compound capable of forming a primary or secondary amine, examples of a compound having an unsaturated bond and a protected amine in the molecule include, but are not limited to, 4,4'-vinylidenebis[N,N-bis(trimethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(triethylsilyl)aniline], 4,4'-vinylidenebis[N,N-bis(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(trimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl ... vinylidenebis[N-methyl-N-(triethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(triethylsilyl)aniline], 4,4'-vinylidenebis[N-methyl-N-(t-butyldimethylsilyl)aniline], 4,4'-vinylidenebis[N-ethyl-N-(t-butyldimethylsilyl)aniline], 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N-methyl-N-(trimethylsilyl)aminophenyl]ethylene, and 1-[4-N,N-bis(trimethylsilyl)aminophenyl]-1-[4-N,N-dimethylaminophenyl]ethylene.

[0187] As a modified agent having a nitrogen atom-containing group and a protected amine compound capable of forming a primary or secondary amine, a compound having an alkoxysilane and a protected amine in the molecule is not particularly limited, but examples thereof include N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane, N,N-bis(triethylsilyl)aminopropylmethyldiethoxysilane, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3 ... Triethylsilyl-1-imidazolidinyl)propyl methyldiethoxysilane, 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyl trimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-(4- trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, and 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane.

[0188] The alkoxysilane compound having a tertiary amine, which is a modifying agent having a nitrogen atom-containing group, is not particularly limited, and examples thereof include 3-dimethylaminopropyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyltriethoxysilane, 3-morpholinopropyltrimethoxysilane, 3-piperidinopropyltriethoxysilane, 3-hexamethyleneiminopropylmethyldiethoxysilane, 3-(4-methyl-1-piperazino)propyltriethoxysilane, 1-[3-(triethoxysilyl) -propyl]-3-methylhexahydropyrimidine, 3-(4-trimethylsilyl-1-piperazino)propyltriethoxysilane, 3-(3-triethylsilyl-1-imidazolidinyl)propylmethyldiethoxysilane, 3-(3-trimethylsilyl-1-hexahydropyrimidinyl)propyltrimethoxysilane, 3-dimethylamino-2-(dimethylaminomethyl)propyltrimethoxysilane, bis(3-dimethoxymethylsilylpropyl)-N-methylamine, bis(3-trimethoxysilylpropyl)-N-methylamine, bis(3-trimethylsilylpropyl)-N-methylamine, N,N,N',N'-tetra(3-trimethoxysilylpropyl)ethylenediamine, 3-isocyanatopropyltrimethoxysilane, 3-cyanopropyltrimethoxysilane, 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-diethoxy-1-(3-triethoxysilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1- (4-trimethoxysilylbutyl)-1-aza-2-silacyclohexane, 2,2-dimethoxy-1-(3-dimethoxymethylsilylpropyl)-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-phenyl-1-aza-2-silacyclopentane, 2,2-diethoxy-1-butyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-1-methyl-1-aza-2-silacyclopentane, 2,2-dimethoxy-8-(4-methylpiperazinyl)methyl-1,6-dioxa-2-silacyclooctane, 2,2-dimethoxy-8-(N,N-diethylamino)methyl-1,6-dioxa-2-silacyclooctane.

[0189] Particularly preferred examples of the alkoxysilane compound having a tertiary amine as a modifier having a nitrogen atom-containing group include tris(3-trimethoxysilylpropyl)amine, tris(3-triethoxysilylpropyl)amine, tris(3-tripropoxysilylpropyl)amine, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]amine, tetrakis(3-trimethoxysilylpropyl)-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-meth 3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tris(3-trimethoxysilylpropyl)-[3-(1-methoxy-2-methyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, bis(3-triethoxysilylpropyl)-[3-(2,2-diethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-ethoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-1,3-propanediamine, tetrakis(3 -trimethoxysilylpropyl)-1,3-bisaminomethylcyclohexane, tris(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-1,3-bisaminomethylcyclohexane, tetrakis(3-trimethoxysilylpropyl)-1,6-hexamethylenediamine, pentakis(3-trimethoxysilylpropyl)-diethylenetriamine, tris(3-trimethoxysilylpropyl)-methyl-1,3-propanediamine, tetrakis[3-(2,2-dimethoxy-1- aza-2-silacyclopentane)propyl]silane, bis(3-trimethoxysilylpropyl)-bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)silane, tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]silane, 3-tris[2-(2,2-dimethoxy-1-aza-2-silacyclopentane)ethoxy]silyl-1-trimethoxysilylpropane, 1-[3-(1-methoxy-2-trimethylsilyl-1-sila-2-azacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 1-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexane, 3,4,5-tris(3-trimethoxysilylpropyl)-cyclohexyl-[3 -(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]ether, (3-trimethoxysilylpropyl)phosphate, bis(3-trimethoxysilylpropyl)-[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate, bis[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]-(3-trimethoxysilylpropyl)phosphate, and tris[3-(2,2-dimethoxy-1-aza-2-silacyclopentane)propyl]phosphate.

[0190] In this embodiment, two or more types of denaturing agents may be used, and the denaturing agents may be added simultaneously or separately in the modification step.

[0191] In this embodiment, after the modification step, a condensation reaction step of carrying out a condensation reaction in the presence of a condensation promoter may be further carried out.

[0192] In the conjugated diene polymer of the present embodiment, the conjugated diene portion in the conjugated diene polymer chain may be hydrogenated.

[0193] The method for hydrogenating the conjugated diene portion of the conjugated diene polymer is not particularly limited, and any known method can be used.

[0194] A suitable hydrogenation method is to blow gaseous hydrogen into a polymer solution in the presence of a catalyst. The catalyst is not particularly limited, but examples thereof include heterogeneous catalysts such as catalysts in which precious metals are supported on porous inorganic materials; catalysts in which salts of nickel, cobalt, etc. are solubilized and reacted with organoaluminum, etc.; and homogeneous catalysts such as catalysts using metallocenes such as titanocene. Among these, titanocene catalysts are preferred from the viewpoint of being able to select mild hydrogenation conditions. Hydrogenation of aromatic groups can also be carried out by using a catalyst supported on a precious metal.

[0195] The hydrogenation catalyst is not particularly limited, but examples thereof include (1) supported heterogeneous hydrogenation catalysts in which metals such as Ni, Pt, Pd, Ru, etc. are supported on carbon, silica, alumina, diatomaceous earth, etc., (2) so-called Ziegler-type hydrogenation catalysts using transition metal salts such as organic acid salts or acetylacetone salts of Ni, Co, Fe, Cr, etc. and reducing agents such as organoaluminum, and (3) so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, Zr, etc. Furthermore, the hydrogenation catalyst is not particularly limited, but examples thereof include known hydrogenation catalysts described in JP-B-42-8704, JP-B-43-6636, JP-B-63-4841, JP-B-1-37970, JP-B-1-53851, JP-B-2-9041, and JP-A-8-109219. Preferred hydrogenation catalysts include a reaction mixture of a titanocene compound and a reducing organometallic compound.

[0196] In the method for producing a conjugated diene polymer of the present embodiment, after the modification step, a deactivator, a neutralizer, and the like may be added to the polymer solution, if necessary.

[0197] The quenching agent is not particularly limited, but examples thereof include water; alcohols such as methanol, ethanol, and isopropanol; and the like.

[0198] The neutralizing agent is not particularly limited, but examples thereof include carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, with the majority having 10 carbon atoms); aqueous solutions of inorganic acids, and carbon dioxide gas.

[0199] In the method for producing a conjugated diene polymer of the present embodiment, it is preferable to add a rubber stabilizer from the viewpoint of preventing gel formation after polymerization and improving stability during processing.

[0200] The rubber stabilizer is not limited to the following ones, and known ones can be used. For example, antioxidants such as 2,6-di-tert-butyl-4-hydroxytoluene (hereinafter also referred to as "BHT"), n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenol) propionate, and 2-methyl-4,6-bis[(octylthio)methyl]phenol are preferred.

[0201] In order to further improve the productivity of the conjugated diene polymer of the present embodiment and the processability when the polymer is made into a composition containing a filler or the like, a rubber softener can be added as necessary.

[0202] The rubber softener is not particularly limited, but examples thereof include extender oil, liquid rubber, and resin.

[0203] The method of adding the rubber softener to the conjugated diene polymer is not particularly limited, but a preferred method is to add the rubber softener to a conjugated diene polymer solution, mix, and remove the solvent from the resulting polymer solution containing the rubber softener.

[0204] Examples of preferred extender oils include aromatic oils, naphthenic oils, and paraffinic oils. Among these, aromatic substitute oils having a polycyclic aromatic (PCA) content of 3% by mass or less according to the IP346 method are preferred from the viewpoints of environmental safety, oil bleeding prevention, and wet grip properties. Examples of aromatic substitute oils 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).

[0205] Preferred liquid rubbers include, but are not limited to, liquid polybutadiene, liquid styrene-butadiene rubber, and the like.

[0206] The effect of adding liquid rubber is that it improves the processability of a composition containing a conjugated diene polymer and a filler, etc., and also shifts the glass transition temperature of the composition to a lower temperature, which tends to improve the abrasion resistance, low hysteresis loss, and low temperature properties of the vulcanized product.

[0207] Preferred resins include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including paulownia oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, monoolefin oligomers, diolefin oligomers, aromatic hydrocarbon resins, aromatic petroleum resins, hydrogenated aromatic hydrocarbon resins, cyclic aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated paulownia oil resins, hydrogenated oil resins, esters of hydrogenated oil resins and monofunctional or polyfunctional alcohols, etc. These resins may be used alone or in combination of two or more. When hydrogenating, all unsaturated groups may be hydrogenated, or some may be left.

[0208] The effect of adding the resin is to improve the processability of a composition made by blending the conjugated diene polymer with a filler, etc., and also to tend to improve the breaking strength of the vulcanized product. In addition, the glass transition temperature of the composition can be shifted to the higher temperature side, which tends to improve the wet skid resistance.

[0209] The amount of the rubber softener, such as an extender oil, liquid rubber, or resin, added is not particularly limited, but is preferably 1 part by mass or more and 60 parts by mass or less, more preferably 5 parts by mass or more and 50 parts by mass or less, and even more preferably 10 parts by mass or more and 37.5 parts by mass or less, relative to 100 parts by mass of the conjugated diene-based polymer of the present embodiment.

[0210] When the rubber softener is added within the above range, the processability of a composition containing the conjugated diene polymer and a filler or the like is improved, and the breaking strength and abrasion resistance of a vulcanizate tend to be improved.

[0211] (Desolvation process) In the method for producing a conjugated diene polymer according to the present embodiment, a known method can be used to obtain the resulting conjugated diene polymer from the polymer solution. The method is not particularly limited, but examples thereof include a method of separating the solvent by steam stripping or the like, filtering the polymer, and then dehydrating and drying it to obtain the polymer, a method of concentrating the polymer in a flashing tank and then devolatilizing the polymer with a vent extruder or the like, and a method of directly devolatilizing the polymer with a drum dryer or the like.

[0212] The rubber composition of the present embodiment is suitably used as a rubber composition for tires. That is, the tire of the present embodiment contains the rubber composition of the present embodiment.

[0213] The rubber composition for tires is not particularly limited, and can be used in various tire parts such as fuel-efficient tires, all-season tires, high-performance tires, studless tires, tires for vehicles carrying high loads, etc., such as treads, carcasses, sidewalls, beads, etc. In particular, the rubber composition for tires has an excellent balance between abrasion resistance, breaking strength, low hysteresis loss, and wet skid resistance when vulcanized, and is therefore suitably used for the treads of fuel-efficient tires, high-performance tires, and tires for vehicles carrying high loads.

[0214] In addition to being used for tires, the rubber composition of the present embodiment has industrial applicability as well, for example, anti-vibration rubber, vibration-isolating rubber, conveyor belts, soles such as shoe outsoles, weather strips for automobiles, packings and gaskets, sealing materials, waterproof sheets, engine mounts, air springs, rubber gloves, medical and sanitary products, hoses for industrial and various applications, battery cases, adhesives, wire coverings, window frame rubber, rubber stoppers, rubber rollers, and materials for various industrial products. EXAMPLES

[0215] Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present embodiment is not limited in any way to the following examples and comparative examples. Various physical properties in the examples and comparative examples were measured by the methods shown below.

[0216] (Physical Properties 1) Microstructure of Conjugated Diene Polymers Conjugated diene polymers or conjugated diene polymers modified with a modifier (hereinafter also referred to as "modified conjugated diene polymers" and, together with conjugated diene polymers, also referred to as "(modified) conjugated diene polymers") were used as samples, and 50 mg of the sample was dissolved in 10 mL of carbon disulfide to prepare a measurement sample. Using a solution cell, infrared spectrum was measured in the range of 600 to 1000 cm-1, and the 1,4 cis bond amount (mol%) and 1,2 vinyl bond amount (mol%) of the conjugated diene polymer were calculated from the absorbance at a predetermined wave number according to the calculation formula of the Morero method (method described in D. Morero, A. Santambrogio, L. Porri, F. Clampelli: Chim. e Ind., 41, 758 (1959)). (Measuring device: Fourier transform infrared spectrophotometer "FT-IR230" manufactured by JASCO Corporation)

[0217] (Physical property 2) Branching degree (Bn) The branching degree (Bn) of the conjugated diene polymer was measured by a GPC-light scattering method with a viscosity detector as follows. A conjugated diene polymer was used as a sample, and a gel permeation chromatography (GPC) measuring device (manufactured by Malvern under the trade name "GPCmax VE-2001") was used in which three columns packed with polystyrene gel were connected together, and measurements were performed using three detectors connected in this order: a light scattering detector, an RI detector, and a viscosity detector (manufactured by Malvern under the trade name "TDA305"). Based on standard polystyrene, the absolute molecular weight was calculated from the results of the light scattering detector and the RI detector, and the intrinsic viscosity was calculated from the results of the RI detector and the viscosity detector. Linear polymer has an intrinsic viscosity [η] = -3.883M 0.771 The shrinkage factor (g') was calculated as the ratio of the intrinsic viscosity corresponding to each molecular weight, where M represents the absolute molecular weight. The obtained shrinkage factor (g') was then used to calculate the branching degree (Bn), defined as g' = 6Bn / {(Bn+1)(Bn+2)}. The eluent used was tetrahydrofuran (hereinafter also referred to as "THF") containing 5 mmol / L triethylamine. The columns used were "TSKgel G4000HXL", "TSKgel G5000HXL", and "TSKgel G6000HXL" manufactured by Tosoh Corporation. 20 mg of the measurement sample was dissolved in 10 mL of THF to prepare a measurement solution, and 100 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 1 mL / min.

[0218] (Physical properties 3) Molecular weight, molecular weight distribution Measurement condition 1: A conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC measurement device (manufactured by Tosoh Corporation under the trade name "HLC-8320GPC") having three columns packed with polystyrene gel connected together, and an RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020"), and the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were determined based on a calibration curve obtained using standard polystyrene. The eluent used was tetrahydrofuran (THF) containing 5 mmol / L triethylamine. Three columns, Tosoh Corporation's "TSKgel SuperMultiporeHZ-H" (trade name), were connected, and a Tosoh Corporation's "TSKguardcolumn SuperMP(HZ)-H" (trade name) was connected in front of them as a guard column. 10 mg of the measurement sample was dissolved in 10 mL of THF to prepare a measurement solution, and 10 μL of the measurement solution was injected into a GPC measurement device and measured under conditions of an oven temperature of 40° C. and a THF flow rate of 0.35 mL / min. Among the various samples measured under the above measurement condition 1, samples whose molecular weight distribution (Mw / Mn) was less than 1.6 were measured again under the following measurement condition 2. Samples whose molecular weight distribution was 1.6 or more after measurement under measurement condition 1 were measured again under measurement condition 1. Measurement condition 2: A conjugated diene polymer or a coupled conjugated diene polymer was used as a sample, and a chromatogram was measured using a GPC measurement device having three columns connected together, each column using a polystyrene gel as a packing material. The weight average molecular weight (Mw) and number average molecular weight (Mn) were calculated based on a calibration curve using standard polystyrene. The eluent used was THF containing 5 mmol / L triethylamine. The columns used were the following: guard column: Tosoh Corporation's product name "TSKguardcolumn SuperH-H"; columns: Tosoh Corporation's product names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000". An RI detector (manufactured by Tosoh Corporation under the trade name "HLC8020") was used under the conditions of an oven temperature of 40° C. and a THF flow rate of 0.6 mL / min. 10 mg of a sample to be measured was dissolved in 20 mL of THF to prepare a measurement solution, and 20 μL of the measurement solution was injected into a GPC measurement device for measurement. For samples that were measured under measurement condition 1 and had a molecular weight distribution value of less than 1.6, measurement was performed under measurement condition 2.

[0219] (Physical property 4) Modification rate The modification rate of the conjugated diene polymer was measured by the column adsorption GPC method as follows. The measurement was performed by applying the adsorption property of the modified basic polymer component to a GPC column packed with silica gel, using a coupling conjugated diene polymer as a sample. The amount of a sample solution containing a sample and low molecular weight internal standard polystyrene was adsorbed onto the silica-based column by measuring the difference between the chromatogram measured using a polystyrene-based column and the chromatogram measured using a silica-based column, and the modification rate was calculated. Specifically, the measurements are as follows: In addition, the above-mentioned (Physical property 3) was performed under measurement condition 1. For samples whose molecular weight distribution was 1.6 or more, the measurements were performed under measurement condition 3 below, and for samples whose molecular weight distribution was less than 1.6, the measurements were performed under measurement condition 4 below. Preparation of sample solution: 10 mg of sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare a sample solution. Measurement condition 3: GPC measurement conditions using a polystyrene column: Using a Tosoh Corporation product name "HLC-8320GPC," 10 μL of the sample solution was injected into the device using 5 mmol / L triethylamine-containing THF as the eluent, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.35 mL / min. Three Tosoh Corporation product name "TSKgel SuperMultiporeHZ-H" columns were connected, and a Tosoh Corporation product name "TSKguardcolumn SuperMP(HZ)-H" was connected in front of them as a guard column. Measurement condition 4: 20 μL of the sample solution was injected into the device using THF containing 5 mmol / L triethylamine as the eluent. The guard column was Tosoh Corporation's "TSKguardcolumn SuperH-H" and the columns were Tosoh Corporation's "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000". The column oven temperature was 40°C, and the THF flow rate was 0.6 mL / min. The chromatogram was obtained using an RI detector (Tosoh Corporation's HLC8020). GPC measurement conditions using a silica column: A Tosoh Corporation product name "HLC-8320GPC" was used, THF was used as the eluent, 50 μL of the sample solution was injected into the device, and a chromatogram was obtained using an RI detector under the conditions of a column oven temperature of 40°C and a THF flow rate of 0.5 ml / min. The columns used were Zorbax PSM-1000S, PSM-300S, and PSM-60S, and a guard column "DIOL 4.6 × 12.5 mm 5 micron" was connected to the front of the columns. Calculation method of modification rate: The total peak area of ​​the chromatogram using a polystyrene-based column was set as 100, the peak area of ​​the sample was set as P1, the peak area of ​​the standard polystyrene was set as P2, the total peak area of ​​the chromatogram using a silica-based column was set as 100, the peak area of ​​the sample was set as P3, and the peak area of ​​the standard polystyrene was set as P4, and the modification rate (%) was calculated from the following formula. Denaturation rate (%) = [1-(P2 x P3) / (P1 x P4)] x 100 (where P1+P2=P3+P4=100)

[0220] (Example 1) Modified conjugated diene polymer (sample 1) Two tank-type pressure vessels having an internal volume of 10 L, an internal height (L) to diameter (D) ratio (L / D) of 4.0, an inlet at the bottom and an outlet at the top, and an agitator as a tank-type reactor and a jacket for temperature control were connected together as polymerization reactors. 1,3-butadiene, which had been previously dehydrated, was mixed at 21.7 g / min and n-hexane at 195 g / min. In a static mixer installed in the middle of the pipe supplying this mixed solution to the inlet of the reactor, n-butyllithium for inactivating remaining impurities was added at 0.051 mmol / min, mixed, and then continuously supplied to the bottom of the reactor. Furthermore, 2,2-bis(2-oxolanyl)propane as a polar substance was supplied at a rate of 0.0071 mmol / min, and n-butyllithium as a polymerization initiator was supplied at a rate of 0.108 mmol / min to the bottom of the first reactor, which was vigorously mixed with a stirrer, and the temperature inside the reactor was maintained at 78°C.

[0221] The polymer solution was continuously withdrawn from the top of the first reactor, continuously fed to the bottom of the second reactor, and the reaction was continued at 78°C, and further fed to a static mixer from the top of the second reactor. When the polymerization was sufficiently stable, trimethoxy(4-vinylphenyl)silane (abbreviated as "BS-1" in the table) was added as a branching agent from the bottom of the second reactor at a rate of 0.0057 mmol / min while 1,3-butadiene was polymerized, and polymerization and branching reactions were carried out to obtain a conjugated diene polymer having a branched structure. When the polymerization and branching reactions were further stabilized, a small amount of the conjugated diene polymer solution before the addition of the modifier was withdrawn, and an antioxidant (BHT) was added so that the amount was 0.2 g per 100 g of polymer, and then the solvent was removed, and the Mooney viscosity of the conjugated diene polymer was measured. The measurement results are shown in Table 1. Next, 1,3-dimethylimidazolidinone (abbreviated as "A" in the table) was continuously added as a modifier to the polymer solution flowing out from the outlet of the reactor at a rate of 0.092 mmol / min, and mixed using a static mixer to carry out a modification reaction. At this time, it took 4.8 minutes for the modifier to be added to the polymer solution flowing out from the outlet of the reactor, the temperature was 76°C, and the difference between the temperature in the polymerization process and the temperature before the modifier was added was 2°C.

[0222] Next, an antioxidant (BHT) was continuously added to the modified polymer solution at 0.055 g / min (n-hexane solution) so that the amount was 0.2 g per 100 g of polymer, and the modification reaction was terminated. After that, the solvent was removed by steam stripping to obtain a modified conjugated diene polymer (sample 1). The measurement results of various physical properties of sample 1 are shown in Table 1. represents an integer of 0 to 3, c represents an integer of 0 to 3, and (a+b+c) is 3.

[0223] (Example 2) Modified conjugated diene polymer (sample 2) Except for not adding BS-1 as a branching agent, a modified conjugated diene-based polymer (sample 2) was obtained in the same manner as in Example 1. The physical properties of sample 2 were measured, and the measurement results are shown in Table 1.

[0224] (Example 3) Modified conjugated diene polymer (sample 3) A modified conjugated diene polymer (sample 3) was obtained in the same manner as in Example 2, except that the modifying agent was a mixture of A and 2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (abbreviated as "B" in the table) and the amounts of A and B added were 0.069 mmol / min and 0.0057 mmol / min, respectively. The measurement results of various physical properties of sample 3 are shown in Table 1.

[0225] (Example 4) Modified conjugated diene polymer (sample 4) A modified conjugated diene polymer (sample 4) was obtained in the same manner as in Example 2, except that the modifying agent was a mixture of A and tetraglycidyl-1,3-bisaminomethylcyclohexane (abbreviated as "C" in the table) and the amounts of A and C added were 0.069 mmol / min and 0.0057 mmol / min, respectively. The measurement results of various physical properties of sample 4 are shown in Table 1.

[0226] (Example 5) Modified conjugated diene polymer (sample 5) A modified conjugated diene polymer (sample 5) was obtained in the same manner as in Example 2, except that the modifier was B and the amount added was 0.011 mmol / min. Various physical properties of sample 5 were measured, and the measurement results are shown in Table 1.

[0227] (Example 6) Modified conjugated diene polymer (sample 6) A modified conjugated diene polymer (sample 6) was obtained in the same manner as in Example 2, except that the modifier was B and the amount added was 0.023 mmol / min. The physical properties of sample 6 were measured, and the measurement results are shown in Table 1.

[0228] (Comparative Example 1) Conjugated diene polymer (sample 7) A conjugated diene polymer (sample 7) was obtained in the same manner as in Example 2, except that no modifier A was added. The physical properties of sample 7 were measured, and the measurement results are shown in Table 1.

[0229] (Examples 1 to 6 and Comparative Example 1) Using Samples 1 to 7 as raw rubbers, rubber compositions containing each raw rubber were obtained according to the formulations shown below.

[0230] (Rubber component) Conjugated diene polymers (samples 1-7) :40 parts by mass Natural rubber RSS#3 :60 parts by mass

[0231] (Combination conditions) The amount of each compounding ingredient added is shown in parts by mass per 100 parts by mass of the rubber component. Carbon black (product name "Seat KH (N550)" manufactured by Tokai Carbon Co., Ltd.) :50.0 parts by mass SRAE oil (product name "Process NC140" manufactured by JX Nippon Oil & Energy Corporation) :10.0 parts by mass ·Zinc white: 5.0 parts by mass Stearic acid: 1.0 parts by weight Anti-aging agent (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine): 2.0 parts by mass ·Sulfur: 2.5 parts by mass - Vulcanization accelerator: N-(tert-butyl)-2-benzothiazole sulfenamide) :1.5 parts by mass ·Total: 154.0 parts by mass

[0232] The volume fraction (φ) of the filler under these compounding conditions was calculated to be 18.0 vol%.

[0233] (Mixing method) The above materials were kneaded by the following method to obtain rubber compositions. In the first stage of kneading, raw rubber (samples 1 to 7), carbon black SRAE oil, zinc oxide, and stearic acid were kneaded at a filling rate of 65% and a rotor rotation speed of 30 to 50 rpm using an internal kneader (capacity 0.3 L) equipped with a temperature control device. At this time, the temperature of the internal mixer was controlled, and each rubber composition (compound) was obtained at a discharge temperature of 155 to 160°C. Next, as the second stage of kneading, the compound obtained above was cooled to room temperature, and then an antioxidant was added and kneaded again to improve the dispersion of carbon black. In this case, the discharge temperature of the compound was adjusted to 155 to 160°C by controlling the temperature of the mixer. After cooling, as the third stage of kneading, sulfur and a vulcanization accelerator were added and kneaded with an open roll set at 70°C. Then, the mixture was molded and vulcanized at 160°C for 30 minutes in a vulcanization press. The rubber composition before vulcanization and the rubber composition after vulcanization were evaluated. Specifically, the evaluation was performed by the following method. The results are shown in Table 1.

[0234] (Rating 1) Cold flow resistance The conjugated diene polymer was cut into a sample with a size of L×W×H=40 mm×40 mm×50 mm, and a load of 1 kg was placed on the sample, followed by leaving the sample standing for 24 hours in an environment at 40° C. After leaving the sample standing for 24 hours, the height (H) of the sample was measured, and the average retention rate of two tests was calculated. A higher retention rate indicates better cold flow resistance. The results of Comparative Example 1 were marked with ▲, and the results of the retention rate improved within the range of 5% or more and less than 10% were marked with △, the results of the retention rate improved within the range of 10% or more and less than 20% were marked with ◯, and the results of the retention rate improved by 20% or more were marked with ⊚.

[0235] (Evaluation 2) Compound Mooney Viscosity The compound obtained above after the second mixing and before the third mixing was used as a sample, and the viscosity was measured using a Mooney viscometer in accordance with ISO 289 after preheating at 130°C for 1 minute and rotating the rotor at 2 revolutions per minute for 4 minutes. The lower the compound Mooney viscosity, the better the processability. The result of Comparative Example 1 was marked with ▲, and the case where the processability was improved by 5% or more and less than 10% was marked with △, the case where the processability was improved by 10% or more and less than 20% was marked with ◯, and the case where the processability was improved by 20% or more was marked with ⊚.

[0236] (Rating 3) Tensile strength The tensile strength was measured according to the tensile test method of JIS K6251. The result of Comparative Example 1 was marked with ▲, the case where the tensile strength at break was improved by 10% or more and less than 20% was marked with △, the case where the tensile strength was improved by 20% or more and less than 30% was marked with ◯, and the case where the tensile strength was improved by 30% or more was marked with ◎.

[0237] (Rating 4) Fuel efficiency Using the Rheometrics Scientific viscoelasticity tester "ARES," tan δ was measured in torsion mode at a temperature of 50°C, a frequency of 10Hz, and a strain of 3%, and used as an index of fuel efficiency, with a lower tan δ value indicating better fuel efficiency. The result of Comparative Example 1 was marked ▲, while cases where fuel efficiency was improved by 5% or more but less than 10% were marked △, cases where fuel efficiency was improved by 10% or more but less than 20% were marked ◯, and cases where fuel efficiency was improved by 20% or more were marked ◎.

[0238] (Rating 5) Dynamic magnification The static spring constant (static spring constant) and dynamic spring constant (dynamic spring constant) of the crosslinked rubber composition were measured in accordance with JIS K6385 using ACUMEN3 manufactured by MTS, and the dynamic ratio (dynamic spring constant / static spring constant) was calculated. The lower the dynamic ratio, the better the vibration-proofing properties. The result of Comparative Example 1 was marked with ▲, and cases where the dynamic ratio was improved in the range of 5% or more and less than 10% were marked with △, cases where the dynamic ratio was improved in the range of 10% or more and less than 20% were marked with ◯, and cases where the dynamic ratio was improved by 20% or more were marked with ◎.

[0239] (Rating 6) Pain Effect The storage modulus (G') was measured at 50°C, 10Hz, and 0.1% strain using a Rheometrics Scientific viscoelasticity tester. 0.1 ) and the storage modulus (G') measured at 10% strain. 10 ) to its difference ΔG'(G' 0.1 -G' 10 ) was calculated as the Payne effect. When the volume fraction of the filler is the same, a lower Payne effect value indicates better filler dispersion.

[0240] [Table 1]

[0241] As shown in Table 1, it was confirmed that, compared with Comparative Example 1, Examples 1 to 6 have excellent cold flow resistance, and when vulcanized, the compound has low Mooney viscosity and exhibits good processability. When vulcanized, the Payne effect is low, and the fuel economy, tensile strength, and dynamic magnification are excellent. [Industrial Applicability]

[0242] The conjugated diene polymer according to the present invention has industrial applicability in the fields of tire treads, interior and exterior parts of automobiles, anti-vibration rubber, belts, footwear, foams, various industrial products, and the like.

Claims

1. A crosslinked rubber composition comprising 20 parts by mass or more and 150 parts by mass or less of a filler relative to 100 parts by mass of a rubber component containing at least one conjugated diene-based polymer, A crosslinked rubber composition, in which a volume fraction φ (vol %) of a filler in the crosslinked rubber composition and a Payne effect ΔG′ (MPa) calculated by a viscoelasticity test satisfy the following formula (A): ΔG'<0.34×φ-3.4...(A) (In formula (A), ΔG′ represents the Payne effect obtained as the difference in storage modulus (G′) value when the crosslinked rubber composition is measured at 0.1% strain and 10% strain in a viscoelasticity test under conditions of a temperature of 50° C. and a frequency of 10 Hz in a torsion mode. φ represents the volume fraction (vol %) of the filler in the crosslinked rubber composition.)

2. the conjugated diene polymer is a conjugated diene polymer containing at least one type of conjugated diene monomer unit, the conjugated diene portion of which has a 1,2-vinyl bond content of 10 mol % or more and 25 mol % or less and a 1,4-cis bond content of 40 mol % or less; The molecular weight distribution is 1.05 to 2.

50. The crosslinked rubber composition according to claim 1.

3. The conjugated diene polymer has a modification rate of 20% by mass or more. The crosslinked rubber composition according to claim 1.

4. The conjugated diene polymer has an amino group and an amide group structure represented by the following formula (I) and / or the following formula (II): The crosslinked rubber composition according to claim 1. 【Chemistry 1】 (In formula (I), P represents a conjugated diene polymer containing at least one conjugated diene monomer, R 1 and R 2 each independently represents a hydrocarbon group having 1 to 20 carbon atoms. 【Chemistry 2】 (In formula (II), P represents a conjugated diene polymer containing at least one conjugated diene monomer, R 1 and R 2 each independently represents a hydrocarbon group having 1 to 20 carbon atoms.

5. The conjugated diene polymer has a branching degree (Bn) of 1.1 or more and less than 4.0, as measured by a GPC-light scattering method with a viscosity detector. The crosslinked rubber composition according to claim 1.

6. A vibration-isolating rubber comprising the crosslinked rubber composition according to any one of claims 1 to 5.

7. A tire comprising the crosslinked rubber composition according to any one of claims 1 to 5.

8. A shoe sole comprising the crosslinked rubber composition according to any one of claims 1 to 5.

9. A hose comprising the crosslinked rubber composition according to any one of claims 1 to 5.

10. A sealing material comprising the crosslinked rubber composition according to any one of claims 1 to 5.

11. A rubber roller comprising the crosslinked rubber composition according to any one of claims 1 to 5.

12. A rubber roller comprising the crosslinked rubber composition according to any one of claims 1 to 5.

13. A conveyor belt comprising the crosslinked rubber composition according to any one of claims 1 to 5.

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