Conjugated diene-based polymer and conjugated diene-based polymer composition

Abstract

This conjugated diene-based polymer comprises a structural unit derived from a conjugated diene-based compound, wherein: the content of a structural unit derived from an aromatic vinyl compound is 7% by mass or less; the 1,2-vinyl bond amount in the structural unit derived from the conjugated diene-based compound is 8-22 mol%; the modification rate is 30%-99%; the Mooney viscosity at 100°C is 25-130; the Mooney stress relaxation at 100°C is 0.30-0.85; and the total content of silicon and tin is 50 ppm or less.

Description

Conjugated diene polymer and conjugated diene polymer composition

[0001] The present invention relates to a conjugated diene polymer and a conjugated diene polymer composition.

[0002] Rubber materials containing natural rubber, which has excellent compression set and dynamic magnification, have been proposed for use in anti-vibration rubbers for automobiles, trains, etc. (See, for example, Patent Document 1.) Anti-vibration rubbers and industrial materials generally use carbon black as the filler. Studies have been conducted to improve the dynamic magnification in anti-vibration rubbers by dispersing carbon black (See, for example, Non-Patent Document 1.)

[0003] International Publication No. 2012 / 119918

[0004] Journal of the Society of Rubber Science and Technology of Japan, 1991, Vol. 64, No. 12, pp. 52-58 "Improvement of vibration characteristics by rubber modification"

[0005] However, the polymers disclosed in Patent Document 1 and Non-Patent Document 1 have problems in terms of productivity and quality of the polymers, and there is room for further improvement in the dynamic magnification of the vibration-proof rubber.

[0006] Therefore, an object of the present invention is to provide a conjugated diene polymer and a conjugated diene polymer composition which have no problems in productivity and quality of the conjugated diene polymer, no problems in processability when obtaining the composition, and which are excellent in balance between tensile properties, dynamic magnification and compression set.

[0007] With regard to the productivity and quality mentioned above, the specific objective is to suppress gelation during production and to improve the cold flow properties of the bale molded body.

[0008] The present inventors have conducted extensive research to solve the problems of the prior art described above, and have found that by using a conjugated diene polymer in which the content of aromatic vinyl monomer units, the amount of 1,2-vinyl bonds, the modification rate, the Mooney viscosity, the Mooney stress relaxation, and the total content of silicon and tin are within certain ranges, there are no problems with productivity or quality, and when made into a composition, there are no problems with processability, and an excellent balance between tensile properties, dynamic magnification ratio, and compression set is achieved, leading to the completion of the present invention.

[0009] That is, the present invention is as follows. [1] A conjugated diene polymer containing structural units derived from a conjugated diene compound, wherein the content of structural units derived from an aromatic vinyl compound is 7% by mass or less, the amount of 1,2-vinyl bonds in the structural units derived from the conjugated diene compound is 8 mol % or more and 22 mol % or less, the modification rate is 30% or more and 99% or less, the Mooney viscosity at 100°C is 25 or more and 130 or less, the Mooney stress relaxation at 100°C is 0.30 to 0.85, and the total content of silicon and tin is 50 ppm or less. [2] The conjugated diene polymer according to [1], wherein the glass transition temperature measured by differential scanning calorimetry (DSC) is -86°C or less and -98°C or more. [3] The conjugated diene polymer according to [1] or [2], wherein a molecular weight distribution curve measured by gel permeation chromatography (GPC) has two or more peaks each having a peak area of ​​5% or more, and when the peak with the largest peak area is designated as Peak A, Peak A is located on the lowest molecular weight side among the peaks having a peak area of ​​5% or more, and the area of ​​Peak A is 60% or more and 95% or less. [3-1] The conjugated diene polymer according to [3], wherein the area of ​​Peak A is 70% or more and 94% or less. [3-2] The conjugated diene polymer according to [3] or [3-1], wherein the area of ​​Peak A is 76% or more and 93% or less. [3-3] The conjugated diene polymer according to any of [3] to [3-2], wherein the area of ​​Peak A is 80% or more and 92% or less. [3-4] The conjugated diene polymer according to any of [3] to [3-3], wherein the area of ​​Peak A is more than 80% and 90% or less. [4] The conjugated diene polymer according to [1] or [2], wherein in a molecular weight distribution curve measured by gel permeation chromatography (GPC), there are two or more peaks each having a peak area of ​​5% or more, and when the peak with the largest peak area is designated as Peak A, Peak A is located on the lowest molecular weight side among the peaks having a peak area of ​​5% or more, and the area of ​​Peak A is 80% or more and 95% or less. [4-1] The conjugated diene polymer according to [4], wherein the area of ​​Peak A is 80% or more and 94% or less. [4-2] The conjugated diene polymer according to [4], wherein the area of ​​Peak A is 80% or more and 93% or less.[4-3] The conjugated diene polymer according to [4], wherein the area of ​​Peak A is 80% or more and 92% or less. [4-4] The conjugated diene polymer according to [4], wherein the area of ​​Peak A is 80% or more and 90% or less. [4-5] The conjugated diene polymer according to [4], wherein the area of ​​Peak A is more than 80% and 94% or less. [4-6] The conjugated diene polymer according to [4], wherein the area of ​​Peak A is more than 80% and 93% or less. [4-7] The conjugated diene polymer according to [4], wherein the area of ​​Peak A is more than 80% and 92% or less. [4-8] The conjugated diene polymer according to [4], wherein the area of ​​Peak A is more than 80% and 90% or less. [5] The conjugated diene polymer according to any one of [1] to [4-8], wherein a molecular weight distribution curve measured by gel permeation chromatography (GPC) has two or more peaks each having a peak area of ​​5% or more, and when the peak with the largest peak area is designated as Peak A, Peak A is located on the lowest molecular weight side among the peaks having a peak area of ​​5% or more, and the modification rate of Peak A is 50% or more and 98% or less. [6] The conjugated diene polymer according to any one of [1] to [5], wherein the tin content is 30 ppm or less. [7] A conjugated diene polymer composition comprising: 100 parts by mass of the conjugated diene polymer according to any one of [1] to [6]; and 0.55 parts by mass or more and 1.8 parts by mass or less of a hindered phenol-based antioxidant. [7-1] The conjugated diene polymer composition according to [7], wherein the amount of the hindered phenol-based antioxidant is 0.60 parts by mass or more and 1.5 parts by mass or less. [7-2] The conjugated diene polymer composition according to [7] or [7-1], wherein the amount of the hindered phenol-based antioxidant is 0.65 parts by mass or more and 1.4 parts by mass or less. [8] A conjugated diene polymer composition comprising: 100 parts by mass of the conjugated diene polymer according to any one of [1] to [6], 0.1 parts by mass or more and 1.0 part by mass or less of a sulfur-containing hindered phenol-based antioxidant, and 0.35 parts by mass or more and 1.0 part by mass or less of a sulfur-free hindered phenol-based antioxidant. [8-1] The conjugated diene polymer composition according to [8], wherein the amount of the sulfur-containing hindered phenol-based antioxidant is 0.15 parts by mass or more and 1.0 part by mass or less.[8-2] The conjugated diene polymer composition according to [8] or [8-1], wherein the amount of the sulfur-containing hindered phenol-based antioxidant is from 0.20 parts by mass to 0.9 parts by mass. [8-3] The conjugated diene polymer composition according to any one of [8] to [8-2], wherein the amount of the sulfur-containing hindered phenol-based antioxidant is from 0.25 parts by mass to 0.8 parts by mass. [8-4] The conjugated diene polymer composition according to any one of [8] to [8-3], wherein the amount of the sulfur-free hindered phenol-based antioxidant is from 0.4 parts by mass to 1.0 part by mass. [8-5] The conjugated diene polymer composition according to any one of [8] to [8-4], wherein the amount of the sulfur-free hindered phenol-based antioxidant is from 0.5 parts by mass to 0.95 parts by mass. [8-6] The conjugated diene polymer composition according to any one of [8] to [8-5], wherein the amount of the sulfur-free hindered phenol antioxidant is 0.6 parts by mass or more and 0.9 parts by mass or less. [9] A conjugated diene polymer composition comprising: 100 parts by mass of a rubber component; and 10 parts by mass or more and 300 parts by mass or less of a filler, wherein the rubber component contains 10% by mass or more of the conjugated diene polymer according to any one of [1] to [6], and the filler contains 40% by mass or more of carbon black. [9-1] The conjugated diene polymer composition according to [9], wherein the rubber component contains 15% by mass or more of the conjugated diene polymer.

[10] A vibration-proof rubber comprising the conjugated diene polymer according to any one of [1] to [6] or a crosslinked product thereof, or the conjugated diene polymer composition according to any one of [7] to [9-1] or a crosslinked product thereof.

[11] A power transmission belt comprising the conjugated diene polymer or crosslinked product thereof according to any one of [1] to [6], or the conjugated diene polymer composition or crosslinked product thereof according to any one of [7] to [9-1].

[12] A conveyor belt comprising the conjugated diene polymer or crosslinked product thereof according to any one of [1] to [6], or the conjugated diene polymer composition or crosslinked product thereof according to any one of [7] to [9-1].

[13] A shoe sole comprising the conjugated diene polymer or crosslinked product thereof according to any one of [1] to [6], or the conjugated diene polymer composition or crosslinked product thereof according to any one of [7] to [9-1].

[14] An industrial material comprising the conjugated diene polymer or crosslinked product thereof according to any one of [1] to [6], or the conjugated diene polymer composition or crosslinked product thereof according to any one of [7] to [9-1].

[15] A tire comprising the conjugated diene polymer or crosslinked product thereof according to any one of [1] to [6], or the conjugated diene polymer composition or crosslinked product thereof according to any one of [7] to [9-1].

[0010] According to the present invention, a crosslinked conjugated diene polymer having excellent tensile properties and an excellent balance between dynamic magnification and compression set can be obtained, and a conjugated diene polymer having excellent processability in compound preparation and no problems in productivity or quality can be provided.

[0011] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail.

[0012] The following embodiments are merely examples for explaining the present invention, and the present invention is not limited to the following embodiments. The present invention can be implemented in various modifications within the scope of its gist.

[0013] [Conjugated Diene Polymer] The conjugated diene polymer of the present embodiment contains a structural unit derived from a conjugated diene compound (hereinafter also referred to as a "conjugated diene monomer unit"), and may contain a structural unit derived from an aromatic vinyl compound (hereinafter also referred to as an "aromatic vinyl monomer unit").

[0014] The conjugated diene polymer of the present embodiment has an aromatic vinyl monomer unit content of 7% by mass or less, and a 1,2-vinyl bond content in the conjugated diene monomer units of 8 mol % or more and 22 mol % or less.

[0015] Examples of aromatic vinyl compounds include, but are not limited to, styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of industrial availability. These compounds may be used alone or in combination of two or more.

[0016] Furthermore, conjugated diene compounds 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, from the viewpoint of ease of industrial availability, 1,3-butadiene and isoprene are preferred, and 1,3-butadiene is particularly preferred. These may be used alone or in combination of two or more.

[0017] The conjugated diene polymer of the present embodiment is characterized in that the so-called microstructure (content of aromatic vinyl monomer units, amount of 1,2-vinyl bonds, etc.) of the copolymer of a conjugated diene compound and an aromatic vinyl compound is controlled.

[0018] (Aromatic Vinyl Monomer Unit Content) The aromatic vinyl monomer unit content of the conjugated diene polymer of this embodiment is 7% by mass or less, preferably 6% by mass or less, more preferably 5% by mass or less, even more preferably 4% by mass or less, still more preferably 3% by mass or less, and particularly preferably 1% by mass or less, from the viewpoint of improving the dynamic magnification of a crosslinked conjugated diene polymer, which is a composition using the conjugated diene polymer of this embodiment and will be described later. On the other hand, from the viewpoint of suppressing an increase in viscosity in the solution and after solvent removal, the content is preferably 1% by mass or more, more preferably 2% by mass or more.

[0019] The content of aromatic vinyl monomer units is １ It can be measured by H-NMR, specifically by the method described in the examples.

[0020] The content of the aromatic vinyl monomer unit can be controlled within the above range by adjusting the amount of the aromatic vinyl compound added during polymerization.

[0021] (Aromatic Vinyl Block Content) In terms of dynamic magnification, the conjugated diene polymer of the present embodiment preferably has an aromatic vinyl block content of 7% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, and may even be 0% by mass.

[0022] The aromatic vinyl block content in the present application can be measured by the method described in I. M. Kolthoff, et al., J. Polym. Sci. 1, 429 (1946), more specifically, by the method described in the Examples.

[0023] (1,2-Vinyl Bond Amount) The 1,2-vinyl bond amount in the conjugated diene polymer of this embodiment is the molar ratio of 1,2-vinyl bonds based on the content of conjugated diene monomer units, and is 8 mol% or more, preferably 13 mol% or more, and more preferably 14 mol% or more, from the viewpoint of productivity of the conjugated diene polymer. On the other hand, from the viewpoint of improving the dynamic magnification and tensile properties of the conjugated diene polymer of this embodiment, and further from the viewpoint of suppressing gelation of the conjugated diene polymer, it is 22 mol% or less, preferably 21 mol% or less, more preferably 20 mol% or less, and even more preferably less than 20 mol%.

[0024] The amount of 1,2-vinyl bond is １ It can be measured by H-NMR, specifically by the method described in the examples.

[0025] The amount of 1,2-vinyl bonds can be controlled within the above range by adjusting the reaction initiation temperature, reaction termination temperature, and the type and amount of polar substance added during polymerization.

[0026] The polymerization method for the conjugated diene polymer of the present embodiment is not limited to the following, but living anionic polymerization is preferred, and adiabatic polymerization is preferred.

[0027] From the viewpoint of increasing the reaction rate and improving productivity, the reaction temperature is preferably a polymerization initiation temperature of 25° C. or higher and 60° C. or lower, more preferably 25° C. or higher and 55° C. or lower, and even more preferably 25° C. or higher and 50° C. or lower. From the viewpoint of increasing the polymerization addition rate of the monomer, the polymerization termination temperature is preferably 65° C. or higher, more preferably 68° C. or higher, and even more preferably 70° C. or higher. On the other hand, from the viewpoint of increasing the modification rate, the temperature is preferably 95° C. or lower, more preferably 85° C. or lower, even more preferably 82° C. or lower, and particularly preferably 80° C. or lower.

[0028] (Number of Peaks, Peak Molecular Weight, Peak Area, and Molecular Weight Distribution in Molecular Weight Distribution Curve in GPC Measurement) The conjugated diene polymer of the present embodiment preferably has two or more peaks with a peak area of ​​5% or more, and may have three or more peaks, from the viewpoints of cold flow properties and processability, when measured by GPC (gel permeation chromatography). On the other hand, from the viewpoint of improving the reproducibility of polymerization, the number of peaks with a peak area of ​​5% or more is preferably five or less, more preferably four or less, even more preferably three or less, and particularly preferably two.

[0029] In the conjugated diene polymer of the present embodiment, the peak derived from the conjugated diene polymer in the molecular weight distribution curve measured by GPC (gel permeation chromatography) refers to a portion sandwiched between the baseline or the minimum value. In the present application, the peak refers to a peak having a peak area of ​​2% or more.

[0030] The peak top molecular weight (also referred to as "peak molecular weight") is the molecular weight at which the value becomes 0 when the molecular weight distribution curve of the peak derived from the conjugated diene polymer in the molecular weight distribution curve is differentiated.

[0031] When the conjugated diene polymer of the present embodiment is measured by GPC (gel permeation chromatography), and the peak with the largest peak area is designated as Peak (A), Peak (A) is preferably the peak located on the lowest molecular weight side among peaks with a peak area of ​​5% or more. When the conjugated diene polymer has two or more peaks with the largest area and a plurality of peaks with the same area exist, the peak with the smaller molecular weight is designated as Peak (A).

[0032] The peak molecular weight of peak (A) is preferably 250,000 or more, more preferably 300,000 or more, even more preferably 350,000 or more, and particularly preferably 380,000 or more, from the viewpoint of reducing adhesion during production and improving the tensile properties of the crosslinked conjugated diene polymer. On the other hand, from the viewpoint of processability, it is preferably 1,200,000 or less, more preferably 1,000,000 or less, even more preferably 800,000 or less, and particularly preferably 600,000 or less.

[0033] The peak top molecular weight of the peak with the largest area when the conjugated diene polymer of the present embodiment is measured by GPC can be controlled within the above numerical range by controlling the amount of the polymerization initiator and the coupling agent described below added.

[0034] From the viewpoint of tensile properties, the peak area of ​​peak (A) is preferably 60% or more, more preferably 70% or more, even more preferably 76% or more, still more preferably 80% or more, and particularly preferably more than 80%. On the other hand, from the viewpoint of cold flow properties, the peak area is preferably 95% or less, more preferably 94% or less, even more preferably 93% or less, still more preferably 92% or less, and particularly preferably 90% or less.

[0035] In a molecular weight distribution curve measured by GPC, when there are two or more peaks with a peak area of ​​5% or more and the peak with the largest peak area is designated as peak (A), if peak (A) is located on the lowest molecular weight side among the peaks with a peak area of ​​5% or more and the area of ​​peak (A) is 80% or more and 95% or less, the vibration-proofing properties, tensile properties, and cold flow properties can be further improved.

[0036] The peak area of ​​peak (A) can be controlled within the above range by controlling the amount of the polymerization initiator and the coupling agent described below.

[0037] Peak (A) is the peak with the largest area when measured by GPC, and is preferably located on the lowest molecular weight side of the peaks. Furthermore, the conjugated diene polymer contained in peak (A) is preferably a polymer with a high linearity, and it is also preferable that the ratio of modified polymer is high. It is presumed that by modifying the terminal of the highly linear polymer, steric hindrance around the modifying group is small, making it easier to interact with the functional group of the filler, thereby improving the dispersibility of the filler and improving the dynamic magnification.

[0038] In the conjugated diene polymer of this embodiment, when measured by GPC (gel permeation chromatography), the peak with the highest molecular weight, excluding the peak (A), is designated as peak (B). From the viewpoint of cold flow properties, the peak molecular weight of peak (B) is preferably 500,000 or more, more preferably 550,000 or more, and even more preferably 600,000 or more. From the viewpoint of gelation suppression, it is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,200,000 or less.

[0039] (Molecular Weight Distribution) From the viewpoint of processability, the conjugated diene polymer of the present embodiment has a molecular weight distribution of preferably 1.02 or more, more preferably 1.03 or more, and even more preferably 1.05 or more. On the other hand, from the viewpoint of a balance between fuel economy performance and grip performance, the molecular weight distribution is preferably 2.5 or less, more preferably 2.0 or less, even more preferably 1.8 or less, and even more preferably 1.5 or less.

[0040] The number of peaks, molecular weight distribution, and peak top molecular weight of the conjugated diene polymer of this embodiment can be measured by gel permeation chromatography (GPC), and detailed conditions will be described in the examples below.

[0041] (Mooney Viscosity, Mooney Stress Relaxation) From the viewpoint of the tensile properties of the conjugated diene polymer crosslinked product, the conjugated diene polymer of the present embodiment has a Mooney viscosity at 100°C of 25 or more, preferably 30 or more, more preferably 35 or more, and even more preferably 40 or more. On the other hand, from the viewpoint of suppressing gelation in the production process, the Mooney viscosity is 130 or less, preferably 110 or less, more preferably 100 or less, and particularly preferably 90 or less.

[0042] The Mooney viscosity of the conjugated diene polymer can be measured by the method described in the examples below.

[0043] The conjugated diene polymer of this embodiment has a Mooney stress relaxation at 100°C of 0.85 or less, more preferably 0.80 or less, even more preferably 0.76 or less, and particularly preferably 0.7 or less, from the viewpoint of suppressing cold flow of the bale. On the other hand, from the viewpoint of suppressing gelation in the production process, the Mooney stress relaxation is 0.30 or more, preferably 0.35 or more, more preferably 0.40 or more, and even more preferably 0.45 or more.

[0044] The Mooney stress relaxation of the conjugated diene polymer at 100° C. can be measured by the method described in the examples below.

[0045] The Mooney viscosity can be controlled by the microstructure, molecular weight, molecular weight distribution, and the ratio of branched components formed by the coupling reaction described below of the conjugated diene polymer.

[0046] Mooney stress relaxation is greatly affected by the entanglement of conjugated diene polymer chains, and can be controlled by the molecular weight and the ratio of branched components.

[0047] (Glass Transition Temperature) From the viewpoint of dynamic magnification and low-temperature characteristics, the glass transition temperature of the conjugated diene polymer of the present embodiment is preferably −86° C. or lower, more preferably −87° C. or lower, still more preferably −89° C. or lower, and particularly preferably −90° C. or lower. On the other hand, from the viewpoint of polymerization reproducibility in living anionic polymerization, the glass transition temperature is preferably −98° C. or higher, more preferably −97° C. or higher, and even more preferably −96° C. or higher.

[0048] The glass transition temperature can be measured by the method described in the Examples below.

[0049] The glass transition temperature can be controlled within a predetermined range by adjusting the ratio of conjugated diene monomer units to aromatic vinyl monomer units in the conjugated diene polymer or the amount of 1,2 vinyl bonds, and the amount of 1,2 vinyl bonds can be controlled by adjusting the amount of polar substance added during polymerization or the polymerization temperature.

[0050] (Coupling) The conjugated diene polymer of the present embodiment may be a conjugated diene polymer obtained by subjecting active terminals of a conjugated diene polymer obtained through a polymerization step to a coupling reaction using a bifunctional or higher functional reactive compound (hereinafter also referred to as a "coupling agent").

[0051] In the coupling reaction step, a coupling agent is used to cause a coupling reaction at one active end of the conjugated diene polymer to obtain a conjugated diene polymer.

[0052] The coupling agent is not particularly limited, and examples thereof include coupling agents having one or more functional groups such as an epoxy group, a carbonyl group, a carboxylic acid ester group, a carboxylic acid amide group, an acid anhydride group, a phosphate ester group, a phosphite ester group, an epithio group, a thiocarbonyl group, a thiocarboxylic acid ester group, a dithiocarboxylic acid ester group, a thiocarboxylic acid amide group, an imino group, an ethyleneimino group, a halogen group, an alkoxysilyl group, an isocyanate group, a thioisocyanate group, a conjugated diene group, and an arylvinyl group. Among the coupling agents, nitrogen-containing coupling agents can also be used as modifiers, which will be described later.

[0053] Examples of coupling agents include, but are not limited to, halogenated silane compounds such as silicon tetrachloride, silicon tetrabromide, silicon tetraiodide, monomethyltrichlorosilicon, monoethyltrichlorosilicon, monobutyltrichlorosilicon, monohexyltrichlorosilicon, monomethyltribromosilicon, and bistrichlorosilylethane; and halogenated silane compounds such as monochlorotrimethoxysilane, monobromotrimethoxysilane, dichlorodimethoxysilane, dibromodimethoxysilane, trichloromethoxysilane, and tribromomethoxysilane.

[0054] Further, examples include, but are not limited to, alkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, and alkyltriphenoxysilane; and compounds having an imino group and an alkoxysilyl group such as tristrimethoxysilylpropylamine, triethoxysilylpropylamine, N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1,3-dimethylbutylidene)-3-(tributoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, and N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole.

[0055] Furthermore, examples thereof include, but are not limited to, 2-[3-(trimethoxysilyl)propyl]-1,3-dimethylimidazolidinone, 2-[3-(trimethoxysilyl)propyl]-1,3-(bistrimethylsilyl)imidazolidinone, 2-(diethoxydiethylsilyl)-1,3-diethylimidazolidinone, 2-(triethoxysilyl)-1,4-diethylpiperazine, 2-(dimethoxymethylsilyl)-1,4-dimethylpiperazine, 5-(triethoxysilyl)-1,3-dipropylhexahydropyrimidine, 5-(dieth ...ethylhexahydropyrimidine, 5-(diethoxysilyl)-1,3-dipropylhexahydropyrimidine, 5-(diethoxysilyl)-1,3-diethylhexahydropyrimidine, 5-(diethoxysilyl)-1,3-dipropylhexahydropyrimidine, 5-(diethoxysilyl)-1,3-diethylhexahydropyrimidine, 5-(diethoxysilyl)-1 {2-[3-(2-dimethylaminoethyl)-2-(ethyldimethoxysilyl)-imidazolidinone-1-yl]-ethyl}-dimethylamine, 5-(trimethoxysilyl)-1,3-bis-(2-methoxyethyl)-hexahydropyrimidine, 5-(ethyldimethoxysilyl)-1,3-bis-(2-trimethylsilylethyl)-hexahydropyrimidine-1,3-dimethylimidazolidinone, 2-(3-diethoxyethylsilyl-propyl)-1,3-diethylimidazolidinone non, 2-(3-triethoxysilyl-propyl)-1,4-diethylpiperazine, 2-(3-dimethoxymethylsilyl-propyl)-1,4-dimethylpiperazine, 5-(3-triethoxysilyl-propyl)-1,3-dipropylhexahydropyrimidine, 5-(3-diethoxyethylsilyl-propyl)-1,3-diethylhexahydropyrimidine, {2-[3-(2-dimethylaminoethyl)-2-(3-ethyldimethoxysilyl-propyl)-imidazolidinon-1-yl]-ethyl}-dimethylamine, 5-(3-trimethoxysilyl-propyl)-1,4-diethylpiperazine, 2-[3-(trimethoxysilyl)propyl]-1,3-bis(trimethylsilyl)imidazolidinone, 2-(diethoxyethylsilyl)-1,3-bis(triethylsilyl)imidazolidinone, 2-(triethoxysilyl)-1,4-bis(trimethylsilyl)piperazine, 2-(dimethoxymethylsilyl)-1,Examples include 4-bis(trimethylsilyl)piperazine and 5-(triethoxysilyl)-1,3-bis(tripropylsilyl)hexahydropyrimidine.

[0056] Furthermore, examples of the silanes include, but are not limited to, [3-(1-hexamethyleneimino)propyl]triethoxysilane, [3-(1-hexamethyleneimino)propyl]trimethoxysilane, [2-(1-hexamethyleneimino)ethyl]triethoxysilane, [2-(1-hexamethyleneimino)ethyl]trimethoxysilane, [3-(1-pyrrolidinyl)propyl]triethoxysilane, [3-(1-pyrrolidinyl)propyl]trimethoxysilane, [3-(1-heptamethyleneimino)propyl]triethoxysilane, [3-(1-do [3-(1-hexamethyleneimino)propyl]triethoxysilane, [3-(1-hexamethyleneimino)propyl]diethoxymethylsilane, [3-(1-hexamethyleneimino)propyl]diethoxyethylsilane, N-[3-(triethoxysilyl)propyl]-N,N'-diethyl-N'-trimethylsilyl-ethane-1,2-diamine, N-[2-(trimethoxysilanyl)ethyl]-N,N',N'-trimethylethane-1,2-diamine, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, and the like.

[0057] Furthermore, examples of the epoxy compounds include, but are not limited to, tetraglycidyl meta-xylene diamine, tetraglycidyl aminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidyl aminomethyl cyclohexane, tetraglycidyl-1,3-bisaminomethyl cyclohexane, 1,3-bis(N,N-diglycidyl aminomethyl) cyclohexane, etc. Furthermore, examples of the epoxy compounds include, but are not limited to, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, diphenylethane diisocyanate, 1,3,5-benzene triisocyanate, etc.

[0058] In addition, examples thereof include, but are not limited to, 3-(4-methylpiperazin-1-yl)propyltriethoxysilane, 1-[3-(diethoxyethylsilyl)propyl]-4-methylpiperazine, 1-[3-(trimethoxysilyl)propyl]-3-methylimidazolidinone, 1-[3-(diethoxysilyl)propyl]-3-ethylimidazolidinone, 1-[3-(triethoxysilyl)propyl]-3-methylhexahydropyrimidine, 1-[3-(di 3-[3-(trimethoxymethylsilyl)propyl]-1-methyl-1,2,3,4-tetrahydropyrimidine, 3-[3-(dimethoxymethylsilyl)propyl]-1-ethyl-1,2,3,4-tetrahydropyrimidine, 1-(2-ethoxyethyl)-3-[3-(trimethoxysilyl)propyl]imidazolidinone, (2-{3-[3-(trimethylsilyl)propyl]tetra hydropyrimidin-yl}ethyl)dimethylamine, 1-[3-(triethoxysilyl)propyl]-4-(trimethylsilyl)piperazine, 1-[3-(dimethoxymethylsilyl)propyl]-4-(trimethylsilyl)piperazine, 1-[3-(tributoxysilyl)propyl]-4-(trimethylsilyl)piperazine, 1-[3-(diethoxyethylsilyl)propyl]-3-(triethylsilyl)imidazolidinone, 2-(trimethoxysilanilide

[0033] Examples of suitable methylsilyl compounds include 1-[3-(triethoxysilyl)propyl]-1,3-dimethylimidazolidinone, 1-[3-(triethoxysilyl)propyl]-3-(trimethylsilyl)imidazolidinone, 1-[3-(dimethoxymethylsilyl)propyl]-3-(trimethylsilyl)hexahydropyrimidine, 1-[3-(triethoxysilyl)propyl]-3-(trimethylsilyl)hexahydropyrimidine, and 1-[4-(triethoxysilyl)propyl]-4-(trimethylsilyl)piperazine.

[0059] (Modification) The conjugated diene polymer of the present embodiment may be modified.

[0060] The term "modification" refers to modifying a conjugated diene polymer with a nitrogen-containing compound.

[0061] The modification method is not particularly limited, but examples thereof include a method using a polymerization initiator containing a nitrogen-containing compound, a method using a nitrogen-containing compound as a polymerization monomer, a method using the above-mentioned nitrogen atom-containing coupling agent, a method reacting a non-coupling nitrogen-containing compound with the reaction terminal, and a method of modifying the double bond of a conjugated diene polymer after polymerization by reacting a nitrogen-containing compound with the double bond.

[0062] Examples of the polymerization initiator containing a nitrogen-containing compound include, but are not limited to, reaction products of nitrogen-containing compounds such as dimethylamine, diethylamine, dibutylamine, dipropylamine, diheptylamine, dihexylamine, dioctylamine, di(2-ethylhexyl)amine, didecylamine, ethylpropylamine, ethylbutylamine, ethylbenzylamine, methylphenethylamine, piperidine, hexamethyleneimine, azacyclooctane, 1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, 1,2,3,6-tetrahydropyridine, and 3,5-dimethylpiperidine with organolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, n-propyllithium, and i-propyllithium.

[0063] Furthermore, examples of non-coupling nitrogen-containing compounds include, but are not limited to, 1,3-diethyl-2-imidazolinone, 1,3-dimethyl-2-imidazolinone, 1,3-dipropyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 1-methyl-3-propyl-2-imidazolinone, 1-methyl-3-butyl-2-imidazolinone, 1,3-dihydro-1,3-dimethyl-2H-imidazol-2-one, N-methyl-2-pyrrolidone, 1-phenyl-2-pyrrolidone, and N-methyl-ε-caprolactam.

[0064] (Modification Ratio) In this specification, unless otherwise specified, the "modification ratio" represents the mass ratio of the polymer having a nitrogen atom-containing functional group to the total amount of the conjugated diene polymer.

[0065] For example, when a nitrogen atom-containing modifying agent is reacted with the terminal end of a polymer, the mass ratio of the polymer having a nitrogen atom-containing functional group due to the nitrogen atom-containing modifying agent to the total amount of the polymer is expressed as the modification rate.

[0066] As mentioned above, the nitrogen atom-containing coupling agent is also included in the nitrogen atom-containing modifying agent.

[0067] On the other hand, when a polymer is branched using a branching agent containing a nitrogen atom, the resulting copolymer will also have a nitrogen atom-containing functional group, and therefore this branched polymer will also be counted as a polymer having a nitrogen atom-containing functional group when calculating the modification rate.

[0068] That is, in this specification, the polymer having a nitrogen atom-containing functional group refers to a polymer having a nitrogen atom-containing functional group formed by a nitrogen atom-containing modifying agent and a branched polymer formed by a branching agent having a nitrogen atom-containing functional group, and the total mass ratio of these is the "modification rate."

[0069] From the viewpoint of dynamic magnification, the conjugated diene polymer of this embodiment has a modification rate (hereinafter also simply referred to as "modification rate") measured by a column adsorption GPC method described below relative to the total amount of the conjugated diene copolymer of 30% or more, preferably 40% or more, more preferably 45% or more, even more preferably 50% or more, and particularly preferably 55% or more. On the other hand, since it is difficult to remove impurities during polymerization and from the viewpoint of increasing productivity, the modification rate is 99% or less, preferably 97% or less, more preferably 95% or less, and even more preferably 93% or less.

[0070] The modification rate can be controlled by keeping the amount of modifier added and the polymerization temperature low, thereby suppressing the deactivation of living ends.

[0071] The modification rate of the conjugated diene polymer of the present embodiment can be measured, for example, by chromatography, which can separate functional group-containing modified components from unmodified components.

[0072] Examples of such methods using chromatography include a method in which a gel permeation chromatography column is used, packed with a polar substance such as silica that adsorbs specific functional groups, and the non-adsorbed components are quantitatively determined using an internal standard for comparison (column adsorption GPC method).

[0073] More specifically, the modification rate can be determined by measuring the amount of adsorption onto the silica column from the difference between a chromatogram obtained by measuring a sample solution containing a sample and a low-molecular-weight internal standard polystyrene on a polystyrene gel column and a chromatogram obtained by measuring the sample solution on a silica column.

[0074] More specifically, the modification rate can be measured by the method described in the Examples.

[0075] The modification rate of the conjugated diene polymer of this embodiment can be controlled within the above-mentioned range by, for example, controlling the amount of the modifying agent added and the polymerization reaction temperature to prevent deactivation of the active terminals.

[0076] (Modification Ratio of Each Peak) The conjugated diene polymer of this embodiment preferably has two or more peaks with a peak area of ​​5% or more in a molecular weight distribution curve measured by GPC. In this case, when the peak with the largest peak area is designated as Peak (A) and the peak with the highest molecular weight excluding Peak (A) is designated as Peak (B), the modification ratio of the conjugated diene polymer contained in Peak (A) is preferably 50% or more, more preferably 60% or more, and even more preferably 65% ​​or more, from the viewpoints of filler dispersibility and improvement of dynamic magnification ratio. On the other hand, from the viewpoints of processability and ease of polymerization, it is preferably 98% or less, more preferably 96% or less, and even more preferably 92% or less.

[0077] The modification rate of the conjugated diene polymer contained in the peak (B) is preferably 85% or more, more preferably 90% or more, from the viewpoint of improving the bound rubber.

[0078] (Total Content of Silicon and Tin, Tin Content) From the viewpoint of improving dynamic magnification and production stability, the conjugated diene polymer of the present embodiment has a total silicon and tin content of 50 ppm or less, preferably 40 ppm or less, more preferably 30 ppm or less, even more preferably 20 ppm or less, and particularly preferably 15 ppm or less.

[0079] Furthermore, from the viewpoint of improving filler dispersibility, the conjugated diene polymer of the present embodiment preferably has a tin content of 30 ppm or less, more preferably 20 ppm or less, even more preferably 10 ppm or less, and particularly preferably contains no tin.

[0080] In the present embodiment, the content of silicon or tin in the conjugated diene polymer refers to the content of silicon or tin bonded to the conjugated diene polymer, and does not include the content of silicon-containing compounds or tin-containing compounds added as additives to the polymer.

[0081] The silicon content and tin content of the conjugated diene polymer of the present embodiment can be controlled by the type of monomer used in the polymerization, the type of coupling agent and the type of modifier and the amount of addition thereof.

[0082] (Method for producing conjugated diene polymer) The conjugated diene polymer of this embodiment is obtained by carrying out a polymerization step in which an aromatic vinyl compound and a conjugated diene compound are polymerized using a predetermined polymerization initiator. Preferably, a coupling reaction step and / or a modification reaction step may be carried out using the above-mentioned coupling agent or modifying agent, and a hydrogenation step may be carried out thereafter. A branching step may be carried out using a branching agent before the coupling reaction step or the modification step.

[0083] (Polymerization Step) As the polymerization initiator used in the polymerization step, at least an organic monolithium compound can be used.

[0084] The organomonolithium compound is not limited to the following, but examples thereof include low molecular weight compounds and solubilized oligomeric organomonolithium compounds.

[0085] Furthermore, examples of the organic monolithium compound include compounds having a carbon-lithium bond, a nitrogen-lithium bond, and a tin-lithium bond in terms of the bonding mode between the organic group and the lithium.

[0086] The amount of the organic monolithium compound used as the polymerization initiator is preferably determined depending on the structure of the target conjugated diene polymer and the molecular weight of the conjugated diene polymer.

[0087] 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, i.e., tends to be related to the number average molecular weight and / or weight average molecular weight, and peak top molecular weight.

[0088] Therefore, in order to increase the molecular weight, it is advisable to adjust the amount of polymerization initiator used in a direction to decrease it, and in order to decrease the molecular weight, it is advisable to adjust the amount of polymerization initiator used in a direction to increase it.

[0089] As the organic monolithium compound, an alkyllithium compound having a substituted amino group or a dialkylaminolithium is preferred from the viewpoint that it can be used as one method for introducing nitrogen atoms into a conjugated diene polymer.

[0090] In this case, a conjugated diene polymer having a nitrogen atom consisting of an amino group at the polymerization initiation terminal can be obtained.

[0091] 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.

[0092] 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.

[0093] Examples of alkyllithium compounds having an amino group with a structure in which an active hydrogen is protected include, but are not limited to, 3-bistrimethylsilylaminopropyllithium and 4-trimethylsilylmethylaminobutyllithium.

[0094] Examples of dialkylaminolithiums include, but are not limited to, lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium dibutylamide, lithium di-n-hexylamide, lithium diheptylamide, lithium diisopropylamide, lithium dioctylamide, lithium-di-2-ethylhexylamide, lithium didecylamide, lithium ethylpropylamide, lithium ethylbutylamide, lithium ethylbenzylamide, lithium methylphenethylamide, lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium morpholide, 1-lithioazacyclooctane, 6-lithio-1,3,3-trimethyl-6-azabicyclo[3.2.1]octane, and 1-lithio-1,2,3,6-tetrahydropyridine.

[0095] 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.

[0096] The organic monolithium compound is preferably an alkyllithium compound from the viewpoints of industrial availability and ease of control of the polymerization reaction, in which case a copolymer having an alkyl group at the polymerization initiation terminal can be obtained.

[0097] Examples of the alkyllithium compound include, but are not limited to, n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium.

[0098] 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.

[0099] 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.

[0100] Examples of the other organometallic compounds include alkaline earth metal compounds, other alkali metal compounds, and other organometallic compounds.

[0101] 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.

[0102] Examples of organomagnesium compounds include dibutylmagnesium and ethylbutylmagnesium. Examples of other organometallic compounds include organoaluminum compounds.

[0103] In the polymerization step, the polymerization reaction mode is not limited to the following modes, but examples thereof include a batch mode (also called a "batch mode") and a continuous mode.

[0104] In the continuous system, one or more connected reactors can be used. The continuous reactor may be, for example, a tank-type or tubular reactor equipped with a stirrer. 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.

[0105] The batch reactor may be, for example, a tank-type reactor equipped with a stirrer. In the batch reactor, preferably, a monomer, an inert solvent, and a polymerization initiator are fed, and if necessary, a monomer is added continuously or intermittently during polymerization to obtain a polymer solution in the reactor, which is then discharged after the polymerization is completed.

[0106] In the method for producing a conjugated diene polymer of the present embodiment, in order to obtain a conjugated diene polymer having active ends at a high rate, a continuous method is preferred, which allows the polymer to be continuously discharged and subjected to the next reaction in a short time.

[0107] In the polymerization step of the conjugated diene polymer of this embodiment, the polymerization is preferably carried out in an inert solvent. Examples of the inert solvent include, but are not limited to, hydrocarbon solvents such as saturated hydrocarbons and aromatic hydrocarbons. Specific hydrocarbon solvents include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; and hydrocarbons consisting of mixtures thereof.

[0108] 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, and a modified conjugated diene-based polymer with a high modification rate tends to be obtained, which is preferable.

[0109] In the polymerization step, a polar substance (polar compound) may be added. This allows the aromatic vinyl compound to be randomly copolymerized with the conjugated diene compound, and the polar substance tends to be usable as a vinylating agent for controlling the microstructure of the conjugated diene portion. It also tends to be effective in accelerating the polymerization reaction.

[0110] Examples of polar substances include, but are not limited to, ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, and 2,2-bis(2-oxolanyl)propane; tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxide compounds such as potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, and sodium amylate; and phosphine compounds such as triphenylphosphine. These polar substances may be used alone or in combination of two or more.

[0111] The amount of polar substance used is not particularly limited and can be selected depending on the purpose, but is preferably 0.01 moles or more and 30 moles or less per mole of the polymerization initiator.

[0112] Such polar substances (vinylating agents) can be used in an appropriate amount depending on the desired amount of 1,2-vinyl bonds as regulators for the microstructure of the conjugated diene moiety in the conjugated diene polymer. Many polar substances also have an effective randomizing effect in the copolymerization of a conjugated diene compound and an aromatic vinyl compound, and tend to be usable as regulators for adjusting the distribution of the aromatic vinyl compound and the amount of styrene blocks.

[0113] As a method for randomizing the conjugated diene compound and the aromatic vinyl compound, for example, as described in JP-A-59-140211, a copolymerization reaction may be initiated with the whole amount of styrene and a part of 1,3-butadiene, and the remaining 1,3-butadiene may be intermittently added during the copolymerization reaction.

[0114] 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, even more preferably 120° C. or lower, still more preferably 30° C. or higher and 100° C. or lower, and particularly preferably 50° C. or higher and 85° C. or lower. When the temperature is within such a range, it tends to be possible to ensure a sufficient amount of the modifying agent to react with the active terminals after the completion of polymerization.

[0115] (Coupling step, modification step, hydrogenation step) The active terminals of the conjugated diene polymer obtained through the above-mentioned polymerization step and, if necessary, a branching step using a predetermined branching agent may be subjected to a coupling reaction using the above-mentioned coupling agent or a modification reaction using a modifier having a nitrogen atom-containing group. When a nitrogen atom-containing coupling agent is used, the coupling reaction and the modification reaction proceed simultaneously. In addition, a hydrogenation step in which a hydrogenation reaction is carried out as appropriate may be carried out.

[0116] (Deactivator Addition Step, Neutralizer Addition Step) In the method for producing a conjugated diene polymer of this embodiment, a deactivator, a neutralizer, or the like may be added to the polymer solution as needed.

[0117] The quenching agent is not limited to the following, but examples thereof include water; alcohols such as methanol, ethanol, and isopropanol; and the like.

[0118] Examples of the neutralizing agent include, but are not limited to, carboxylic acids such as stearic acid, oleic acid, and versatic acid (a highly branched carboxylic acid mixture having 9 to 11 carbon atoms, mainly 10 carbon atoms); aqueous solutions of inorganic acids; and carbon dioxide gas.

[0119] (Rubber Stabilizer) In the method for producing a conjugated diene polymer composition 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.

[0120] In the method for producing a cross-linked conjugated diene polymer of the present embodiment, it is preferable to use a hindered phenol antioxidant as the rubber stabilizer.

[0121] The conjugated diene polymer composition of the present embodiment preferably contains 0.55 parts by mass or more, more preferably 0.60 parts by mass or more, and even more preferably 0.65 parts by mass or more of the hindered phenol antioxidant per 100 parts by mass of the conjugated diene polymer from the viewpoint of preventing gelation due to heat generated during kneading, while from the viewpoint of cost, the content is preferably 1.8 parts by mass or less, more preferably 1.5 parts by mass or less, and even more preferably 1.4 parts by mass or less.

[0122] Furthermore, hindered phenol-based antioxidants can be further classified into sulfur-containing hindered phenol-based antioxidants and sulfur-free hindered phenol-based antioxidants.

[0123] In the conjugated diene polymer composition of this embodiment, the sulfur-containing hindered phenol antioxidant is preferably contained in an amount of 0.10 parts by mass or more, more preferably 0.15 parts by mass or more, more preferably 0.20 parts by mass or more, and even more preferably 0.25 parts by mass or more, relative to 100 parts by mass of the conjugated diene polymer, from the viewpoints of suppressing gelation during kneading and suppressing oxidative degradation. On the other hand, from the viewpoint of odor, the amount is preferably 1.0 part by mass or less, more preferably 0.9 parts by mass or less, and even more preferably 0.8 parts by mass or less. Furthermore, from the viewpoint of suppressing deterioration due to heat or sunlight after production, the amount of the sulfur-free hindered phenol antioxidant is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, more preferably 0.35 parts by mass or more, more preferably 0.4 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.6 parts by mass or more, relative to 100 parts by mass of the conjugated diene polymer. On the other hand, from the viewpoint of coloring such as yellowing of the molded body, the amount is preferably 1.0 part by mass or less, more preferably 0.95 part by mass or less, and even more preferably 0.9 part by mass or less.

[0124] In the conjugated diene polymer composition of the present embodiment, gelation due to heat generation during kneading can be verified by the method described in the examples.

[0125] In order to sufficiently reduce the risk of gelation and obtain a conjugated diene polymer composition having excellent productivity, the hindered phenol antioxidant is preferably contained in an amount of 0.55 parts by mass or more and 1.8 parts by mass or less per 100 parts by mass of the conjugated diene polymer, and it is more preferable that the sulfur-containing hindered phenol antioxidant is contained in an amount of 0.1 part by mass or more and 1.0 part by mass or less, and the sulfur-free hindered phenol antioxidant is contained in an amount of 0.35 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of the conjugated diene polymer.

[0126] The hindered phenol-based antioxidants may be used alone or in combination of two or more.Similarly, it is preferable to use one or more sulfur-containing hindered phenol-based antioxidants and one or more sulfur-free hindered phenol-based antioxidants in combination, and two or more of each may be used in combination.

[0127] Examples of the hindered phenol compound include, but are not limited to, N-octadecyl-3-(4'-hydroxy-3',5'-di-t-butylphenyl)propionate, tetrakis{methylene-3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate}methane, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, distearyl(4-hydroxy-3-methyl-5-t-butylbenzyl)malonate, triethylenediamine, methyl methyl ester ... ethylene glycol-bis{3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate}, 1,6-hexanediol-bis{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate}, 2,4-bis-(N-octylthio)-6-(4-hydroxyphenyl)-3,5-di-t-butyl-anilino-1,3,5-triazine, 2,2-thiodiethylenebis{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate}, 2 , 2-thiobis(4-methyl-6-t-butylphenol), 2,2'-methylenebis-(4-ethyl-6-t-butylphenol), N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], 3,5-di-t-butyl-4-hydroxybenzylphosphonate diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, bis(3,5-di- t-butyl-4-hydroxybenzyl) sulfide, tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 2,4-bis{(octylthio)methyl}-O-cresol, isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, N,N'-bis{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionylhydrazine, and (meth)acrylate compounds having a hindered phenol structure.

[0128] (Solvent Removal Step) In the method for producing a conjugated diene polymer of the present embodiment, a known method can be used to obtain the resulting conjugated diene polymer from the polymer solution. Examples of the method include, but are not limited to, a method in which the solvent is separated by steam stripping or the like, the polymer is then filtered, and the polymer is then dehydrated and dried to obtain the polymer, a method in which the polymer is concentrated in a flashing tank and then devolatilized using a vent extruder or the like, and a method in which the polymer is directly devolatilized using a drum dryer or the like.

[0129] [Conjugated Diene Polymer Composition] The conjugated diene composition in the present application refers to a composition containing, in addition to the above-mentioned conjugated diene polymer, additives other than the conjugated diene polymer, a rubber component as described below, and the like.

[0130] The conjugated diene polymer composition of the present embodiment contains the conjugated diene polymer of the present embodiment described above in an amount of 10 mass % or more relative to the rubber component (including the conjugated diene polymer of the present embodiment described above) contained in the conjugated diene polymer composition.

[0131] The rubber component is not particularly limited, and may be, for example, natural rubber or synthetic rubber. Synthetic rubber may include, for example, isoprene rubber, butadiene rubber or its hydride, styrene butadiene rubber or its hydride, nitrile rubber or its hydride, urethane rubber, butyl rubber or its halide, ethylene-propylene-diene rubber (EPDM), chloroprene rubber, acrylic rubber, silicone rubber, or fluororubber.

[0132] The conjugated diene polymer composition of the present embodiment preferably contains 10 parts by mass or more, and more preferably 15 parts by mass or more, of a filler relative to 100 parts by mass of the rubber component of the present embodiment from the viewpoints of rigidity and compression set. On the other hand, from the viewpoints of sufficiently dispersing the filler and ensuring that the conjugated diene polymer composition of the present embodiment has practically sufficient processability and mechanical strength, the amount of the filler relative to 100 parts by mass of the rubber component of the present embodiment is preferably 300 parts by mass or less, more preferably 250 parts by mass or less, even more preferably 200 parts by mass or less, and particularly preferably 100 parts by mass or less.

[0133] Examples of fillers include, but are not limited to, silica-based inorganic fillers, carbon black, calcium carbonate, titanium oxide, aluminum hydroxide, and clay. These may be used alone or in combination of two or more. Furthermore, fillers other than those mentioned above may also be contained.

[0134] From the viewpoint of dynamic magnification, the filler used in the conjugated diene polymer composition of the present embodiment preferably contains 40% by mass or more of carbon black, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[0135] The conjugated diene polymer composition of this embodiment includes 100 parts by mass of a rubber component and 10 to 300 parts by mass of a filler, wherein the rubber component preferably includes 10% by mass or more of the conjugated diene polymer of this embodiment, and the filler preferably includes 40% by mass or more of carbon black. This composition can further improve rigidity, vibration-damping properties, and thermal stability. The conjugated diene polymer composition preferably includes 0.55 to 1.8 parts by mass of a hindered phenol-based antioxidant per 100 parts by mass of the conjugated diene polymer. Alternatively, the conjugated diene polymer composition preferably includes 0.1 to 1.0 part by mass of a sulfur-containing hindered phenol-based antioxidant and 0.35 to 1.0 part by mass of a non-sulfur-containing hindered phenol-based antioxidant per 100 parts by mass of the conjugated diene polymer. This composition can further improve thermal stability. Furthermore, it is preferable that the conjugated diene polymer has, in a molecular weight distribution curve measured by GPC, two or more peaks each having a peak area of ​​5% or more, and when the peak with the largest peak area is designated as peak (A), peak (A) is located on the lowest molecular weight side among the peaks each having a peak area of ​​5% or more, and the area of ​​peak (A) is 80% or more and 95% or less. By having such characteristics, the cold flow property can be further improved.

[0136] The silica-based inorganic filler is not limited to the following and any known filler can be used, for example, SiO ２ or Si ３ Solid particles containing Al as a constituent unit are preferred, and SiO ２ or Si ３ Solid particles containing Al as the main component of the structural units are more preferred. Here, the main component refers to a component contained in the silica-based 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.

[0137] Specific silica-based inorganic fillers include, but are not limited to, inorganic fibrous materials such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber.

[0138] Other examples include silica-based inorganic fillers whose surfaces have been made hydrophobic, and mixtures of silica-based inorganic fillers and inorganic fillers other than silica-based inorganic fillers.

[0139] Among these, silica and glass fiber are preferred, and silica is more preferred, from the viewpoints of strength, abrasion resistance, etc. Examples of silica include dry silica, wet silica, and synthetic silicate silica.

[0140] Examples of carbon black include, but are not limited to, carbon blacks of various classes such as SRF, FEF, HAF, ISAF, and SAF. Among these, carbon blacks with a nitrogen adsorption specific surface area of ​​50 m ２ Carbon black having a carbon absorption of 80 mL / 100 g or more and a dibutyl phthalate (DBP) oil absorption of 80 mL / 100 g or less is preferred.

[0141] The calcium carbonate is not particularly limited, but examples thereof include calcium carbonate having an average particle size of 0.04 μm to 8.0 μm and an oil absorption of 10 to 35 g per 100 g of calcium carbonate.

[0142] The filler may contain other fillers in addition to the above fillers. Examples of the other fillers include metal oxides and metal hydroxides. Metal oxides are compounds represented by the chemical formula M ｘ O ｙ(M represents a metal atom, and x and y each independently represent an integer of 1 to 6) as the main component of the structural unit.

[0143] Examples of metal oxides include, but are not limited to, alumina, titanium oxide, magnesium oxide, and zinc oxide.

[0144] Examples of metal hydroxides include, but are not limited to, aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

[0145] The conjugated diene polymer composition of the present embodiment may contain a silane coupling agent.

[0146] The silane coupling agent has the function of strengthening the interaction between the rubber component and the inorganic filler, and has groups that have affinity or bonding properties for both the rubber component and the silica-based inorganic filler. Preferably, the silane coupling agent is a compound that has a sulfur-bonding moiety and an alkoxysilyl group or silanol group moiety in one molecule.

[0147] 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.

[0148] In the conjugated diene polymer composition of this embodiment, the content of the silane coupling agent is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 0.5 parts by mass or more and 20 parts by mass or less, and even more preferably 1.0 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the inorganic filler. When the content of the silane coupling agent is within the above range, the effect of the addition of the silane coupling agent tends to be more pronounced.

[0149] (Rubber Softener) The conjugated diene polymer composition of the present embodiment may contain a rubber softener, if necessary.

[0150] The rubber softener is preferably added from the viewpoint of further improving the productivity of the conjugated diene polymer and the processability of the conjugated diene polymer composition containing a filler or the like.

[0151] Examples of rubber softeners include, but are not limited to, extender oil, liquid rubber, and resin.

[0152] The method of adding a rubber softener to a conjugated diene polymer or a conjugated diene polymer composition is not limited to the following, but a preferred method is to add a rubber softener to a conjugated diene polymer solution, mix them, and remove the solvent from the resulting polymer solution containing the rubber softener.

[0153] Examples of the extender oil include aromatic oil, naphthenic oil, paraffin oil, etc. Among these, from the viewpoint of environmental safety, oil bleed prevention, and wet grip properties, aromatic substitute oils having a polycyclic aromatic (PCA) component content of 3 mass% or less according to the IP346 method are preferred. Examples of aromatic substitute oils include TDAE (Treated Distillate Aromatic Extracts), MES (Mild Extraction Solvate), etc. shown in Kautschuk Gummi Kunststoffe 52(12)799(1999), as well as RAE (Residual Aromatic Extracts).

[0154] The liquid rubber is not limited to the following, but examples thereof include liquid polybutadiene and liquid styrene-butadiene rubber.

[0155] The effects of adding liquid rubber include improving the processability of a conjugated diene polymer composition obtained by blending a conjugated diene polymer with a filler or the like, and also shifting the glass transition temperature of the conjugated diene polymer composition (rubber composition) to a lower temperature, thereby improving the abrasion resistance and low-temperature properties of a vulcanized product.

[0156] Examples of the resin include, but are not limited to, aromatic petroleum resins, coumarone-indene resins, terpene resins, rosin derivatives (including tung oil resins), tall oil, tall oil derivatives, rosin ester resins, natural and synthetic terpene resins, aliphatic hydrocarbon resins, aromatic hydrocarbon resins, mixed aliphatic-aromatic hydrocarbon resins, coumarin-indene resins, phenolic resins, p-tert-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, monoolefin oligomers, diolefin oligomers, hydrogenated aromatic hydrocarbon resins, cyclic aliphatic hydrocarbon resins, hydrogenated hydrocarbon resins, hydrocarbon resins, hydrogenated tung oil resins, hydrogenated oil resins, and esters of hydrogenated oil resins with monofunctional or polyfunctional alcohols.

[0157] These resins may be used alone or in combination of two or more. When hydrogenating, all of the unsaturated groups may be hydrogenated, or some may remain.

[0158] The effects of adding a resin include an effect of improving the processability of the conjugated diene polymer composition (rubber composition) blended with the conjugated diene polymer of this embodiment and a filler, an effect of improving the breaking strength when vulcanized, and an effect of shifting the glass transition temperature of the conjugated diene polymer composition of this embodiment to a higher temperature, thereby improving the tensile properties at high temperatures.

[0159] The amount of extender oil, liquid rubber, resin, or the like added as a rubber softener is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 parts by mass of the conjugated diene-based polymer of the present embodiment.

[0160] When the rubber softener is added within the above range, the processability of the conjugated diene polymer composition containing the conjugated diene polymer of the present embodiment and a filler or the like is improved, and the breaking strength and abrasion resistance of the vulcanized product tend to be improved.

[0161] (Rubber Bale Molded Article) The conjugated diene polymer of the present embodiment can be made into a rubber bale molded article.

[0162] The rubber bale molded body is a mass of a conjugated diene polymer or a conjugated diene polymer composition obtained by compression molding, and can be obtained, for example, by extruding a conjugated diene polymer composition using an extruder, cutting it to obtain crumbs, and then compression molding the crumbs.

[0163] (Cross-linked Conjugated Diene Polymer) The conjugated diene polymer composition of the present embodiment may be a cross-linked composition obtained by subjecting the composition to a cross-linking treatment using a cross-linking agent.

[0164] Examples of crosslinking agents include, but are not limited to, radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur, and sulfur compounds.

[0165] The sulfur compounds include sulfur monochloride, sulfur dichloride, disulfide compounds, polymeric polysulfur compounds, and the like.

[0166] In the conjugated diene polymer composition of this embodiment, the content of the crosslinking agent is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the rubber component containing the conjugated diene polymer of this embodiment. 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.

[0167] In the crosslinking, a vulcanization accelerator may be used as needed.

[0168] As the vulcanization accelerator, conventionally known materials can be used, and examples thereof include, but are not limited to, sulfenamide-based, guanidine-based, thiuram-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, thiourea-based, and dithiocarbamate-based vulcanization accelerators. Furthermore, as the vulcanization aid, examples thereof include, but are not limited to, zinc oxide, stearic acid, and triallyl isocyanurate.

[0169] The content of the vulcanization accelerator is preferably 0.01 parts by mass or more and 20 parts by mass or less, and more preferably 0.1 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of the rubber component containing the conjugated diene polymer of the present embodiment.

[0170] Examples of organic peroxides include, but are not limited to, 1,3-bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexene-3, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 2,2'-bis(tert-butylperoxy)-p-isopropylbenzene, dicumyl peroxide, di-tert-butyl peroxide, tert-butylperoxy Examples of the peroxide include tert-butylperoxybenzoate, p-menthane peroxide, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, dilauroyl peroxide, diacetyl peroxide, tert-butyl peroxybenzoate, 2,4-dichlorobenzoyl peroxide, p-chlorobenzoyl peroxide, benzoyl peroxide, di(tert-butylperoxy)perbenzoate, n-butyl-4,4-bis(tert-butylperoxy)valerate, and tert-butylperoxyisopropyl carbonate.

[0171] The crosslinked conjugated diene polymer of this embodiment is used for, for example, tires, shoe soles, vibration-proof rubber and vibration-damping materials, rubber belts, power transmission belts, conveyor belts, automobile interiors, hoses, industrial materials, and the like.

[0172] (Method for Producing Conjugated Diene Polymer Cross-Linked Product (Rubber Cross-Linked Product)) As a pretreatment for obtaining the conjugated diene polymer cross-linked product of the present embodiment, the method for mixing various additives with the conjugated diene polymer includes, but is not limited to, a melt-kneading method using a general mixer such as an open roll, a Banbury mixer, a kneader, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder, and a method in which the components are dissolved and mixed and then the solvent is removed by heating.

[0173] Among these, melt-kneading methods using a roll, a Banbury mixer, a kneader, or an extruder are preferred from the viewpoints of productivity and good kneading ability. Also applicable are a method of kneading the rubber component, other fillers, silane coupling agent, and additives all at once, and a method of mixing them in several batches.

[0174] After the mixing step, it is preferable to carry out the crosslinking reaction described above to obtain a crosslinked conjugated diene polymer.

[0175] (Other Additives) The conjugated diene polymer composition (rubber composition) of this embodiment may contain various additives other than those described above, such as softeners and fillers, heat stabilizers, antistatic agents, weather stabilizers, antioxidants, colorants, lubricants, and tackifiers, within the scope of the present embodiment.

[0176] As other softeners, known softeners can be used.

[0177] Known materials can be used for the heat resistance stabilizer, antistatic agent, weather resistance stabilizer, antioxidant, colorant, and lubricant.

[0178] Hereinafter, the present embodiment will be described in more detail by giving specific examples and comparative examples, application examples and application comparative examples, but the present embodiment is not limited in any way by the following examples and comparative examples, application examples and application comparative examples.

[0179] Here, specific examples of conjugated diene polymers are referred to as "Examples" and "Comparative Examples", and specific examples of conjugated diene polymer compositions are referred to as "Application Examples" and "Application Comparative Examples".

[0180] Various physical properties in the Examples, Comparative Examples, Application Examples and Application Comparative Examples were measured by the methods shown below.

[0181] [Method of measuring physical properties] [Areas of Peak (A) and Peak (B), Peak Molecular Weight of Peak (A), Peak Molecular Weight of Peak (B), Number of Peaks with a Peak Area of ​​5% or More] A chromatogram was measured using a GPC measuring device in which three columns packed with polystyrene gel were connected, and the peak top molecular weight of each peak was determined based on a calibration curve using standard polystyrene. In the obtained molecular weight distribution curve, the peak with the largest peak area was designated as Peak (A), and the peak with the highest molecular weight excluding Peak (A) was designated as Peak (B).

[0182] Specific measurement conditions are shown below. Measurement was performed by injecting 20 μL of the following measurement solution into a GPC measurement device. (Measurement conditions) Device: "HLC-8320GPC" manufactured by Tosoh Corporation Eluent: Tetrahydrofuran (THF) containing 5 mmol / L triethylamine Guard column: "TSKguardcolumn SuperH-H" manufactured by Tosoh Corporation Separation column: "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" manufactured by Tosoh Corporation connected in this order Oven temperature: 40°C Flow rate: 0.6 mL / min Detector: RI detector ("HLC8020" manufactured by Tosoh Corporation) Measurement solution: Measurement solution prepared by dissolving 10 mg of the measurement sample in 20 mL of THF

[0183] [Modification Ratio of Conjugated Diene Polymer] The modification ratio was measured by a column adsorption GPC method, taking advantage of the property of the modified polymer to be adsorbed onto a column, as follows: A sample solution containing a sample and a low-molecular-weight internal standard polystyrene was measured using a column packed with a polystyrene-based gel, and a chromatogram was measured using a column packed with a silica-based gel to measure the amount of adsorption onto the silica-based column, and the modification ratio was calculated from the difference between the chromatograms.

[0184] (GPC Measurement Conditions Using a Polystyrene Column) The GPC measurement conditions using a polystyrene column are shown below. Measurements were performed by injecting 20 μL of the following measurement solution into a GPC measurement device. Device: Tosoh Corporation, product name "HLC-8320GPC" Eluent: THF containing 5 mmol / L triethylamine Guard column: Tosoh Corporation, product name "TSKguardcolumn SuperH-H" Column: Tosoh Corporation, product names "TSKgel SuperH5000", "TSKgel SuperH6000", and "TSKgel SuperH7000" connected in this order Oven temperature: 40°C Flow rate: 0.6 mL / min Detector: RI detector (Tosoh Corporation, HLC8020) Measurement solution: 10 mg of sample and 5 mg of standard polystyrene were dissolved in 20 mL of THF to prepare a sample solution.

[0185] (GPC measurement conditions using a silica-based column) The GPC measurement conditions using a silica-based column are shown below. Measurement was carried out by injecting 50 μL of the following measurement solution into a GPC measurement device. Device: "HLC-8320GPC" manufactured by Tosoh Corporation Eluent: THF Guard column: "DIOL 4.6 x 12.5 mm 5 micron" manufactured by GL Sciences Separation column: "Zorbax PSM-1000S", "PSM-300S", and "PSM-60S" manufactured by Agilent Technologies connected in this order Oven temperature: 40°C Flow rate: 0.5 mL / min Detector: RI detector (HLC8020 manufactured by Tosoh Corporation)

[0186] (Method of calculating modification rate) The total peak area of ​​the chromatogram using a polystyrene-based column was set to 100, the peak area of ​​the sample was set to P1, the peak area of ​​the standard polystyrene was set to P2, the total peak area of ​​the chromatogram using a silica-based column was set to 100, the peak area of ​​the sample was set to P3, and the peak area of ​​the standard polystyrene was set to P4, and the modification rate (%) was calculated using the following formula: Modification rate (%) = [1 - (P2 x P3) / (P1 x P4)] x 100 (where P1 + P2 = P3 + P4 = 100)

[0187] [Modification Rates of Peak (A) and Peak (B)] The total area of ​​Peak (A) in the chromatogram using a polystyrene column and the standard polystyrene was set to 100, the peak area of ​​the sample was set to P5, the peak area of ​​the standard polystyrene was set to P6, the total area of ​​Peak (A) in the chromatogram using a silica column and the standard polystyrene was set to 100, the peak area of ​​the sample was set to P7, and the peak area of ​​the standard polystyrene was set to P8. The modification rate (%) of Peak (A) was calculated using the following formula: Modification rate (%) = [1 - (P6 x P7) / (P5 x P8)] x 100 (where P5 + P6 = P7 + P8 = 100) The modification rate of Peak (B) was also calculated in a similar manner.

[0188] [Mooney Viscosity, Mooney Stress Relaxation (MSR)] Using a Mooney viscometer (trade name "VR1132" manufactured by Ueshima Seisakusho Co., Ltd.), the Mooney viscosity and Mooney stress relaxation of each polymer were measured in accordance with JIS K6300 (ISO289-1) and ISO289-4. The measurement temperature was 100°C. Here, the sample was preheated for 1 minute, and the rotor was rotated at 2 rpm. The torque was measured after 4 minutes to determine the Mooney viscosity (ML （１＋４） ) In addition, Mooney stress relaxation was also measured.

[0189] [Glass Transition Temperature] Measurement was carried out according to ISO 22768:2006 using a conjugated diene polymer as a sample. 10 mg of the sample was placed in a dedicated aluminum pan, and a Hitachi High-Tech Science DSC7020 differential scanning calorimeter was used as the measuring device. After heating from 30°C to 160°C at 20°C / min and holding for 2 minutes, the temperature was lowered from 160°C to -120°C at 10°C / min, and then the DSC curve was recorded while increasing the temperature from -120°C to 100°C at 10°C / min. The peak top (inflection point) of the DSC differential curve derived from the glass transition of the conjugated diene polymer when the temperature was increased from -120°C to 100°C was taken as the glass transition temperature.

[0190] [Silicon Content, Tin Content] The conjugated diene polymer obtained in the polymerization examples described below was subjected to elemental analysis using inductively coupled plasma (ICP, Inductive Coupled Plasma, manufactured by Shimadzu Corporation, device name: ICPS-8100) to measure the silicon content (unit: ppm) and tin content (unit: ppm) in the polymer, and the total content was calculated.

[0191] [Styrene Content, Butadiene Content, and Vinyl Bond Amount of Conjugated Diene Polymer] A conjugated diene polymer was used as a sample. １ The bound styrene content, butadiene content, and vinyl bond content were measured by H-NMR measurement.

[0192] １ ​The conditions for H-NMR measurement are as follows: <Measurement conditions> Measurement equipment: JNM-LA400 (manufactured by JEOL) Solvent: deuterated chloroform Measurement sample: conjugated diene polymer Sample concentration: 50 mg / mL Observation frequency: 400 MHz Chemical shift reference: TMS (tetramethylsilane) is contained at 0.05% by mass relative to deuterated chloroform Pulse delay: 2.904 seconds Number of scans: 64 times Pulse width: 45° Measurement temperature: 26°C

[0193] [Styrene Block Content] The content of the aromatic vinyl monomer block (styrene block) was measured according to the osmium tetroxide decomposition method described in I. M. Kolthoff, et al., J. Polym. Sci. 1, 429 (1946). More specifically, 0.050 g of a conjugated diene polymer was dissolved in 10 ml of chloroform, to which 16 mL of a 69% by mass aqueous solution of tert-butyl hydroperoxide and 4.0 mL of a 0.050% by mass chloroform solution of osmium tetroxide were added. The mixture was refluxed in a 90°C bath for 12 minutes to carry out an oxidative decomposition reaction. After completion of the reaction, the reaction solution was cooled, and 200 mL of methanol was added to the reaction solution with stirring to precipitate the styrene block component, which was then filtered through a 5 μm glass filter. The styrene block content was determined by dividing the mass of the resulting product by the total mass of the styrene-butadiene copolymer rubber.

[0194] [Evaluation of Cold Flow Property] The conjugated diene polymers containing a stabilizer obtained in the Examples and Comparative Examples described below were used as measurement samples. Cold flow was measured by applying a load of 1 kg to a sample of 40 mm × 40 mm × thickness (H0) 50 mm at 25°C, leaving it for 60 minutes, and then calculating the thickness change (%) from the thickness (H60) using the following formula: Thickness change (%) = (H0 - H60) × 100 / H0

[0195] If the thickness change rate was 40% or less, there was no practical problem, and therefore, ◯; if it exceeded 40%, severe cold flow occurred during storage, resulting in poor handling properties, and therefore, ◯.

[0196] [Thermal Stability Test (Low Temperature)] The conjugated diene polymer containing the stabilizer obtained in the Examples and Comparative Examples described below was used as the measurement sample. A Laboplastomill 4M150 and a Banbury mixer B75 (mixer capacity 75 cc) manufactured by Toyo Seiki Seisakusho, Ltd. were used. 50 g of the conjugated diene polymer was added to a Banbury mixer heated to 70°C and masticated for 4 minutes at 10 rpm. The rotation speed of the Banbury mixer was then increased so that the temperature exceeded 135°C within 1 to 5 minutes, and the time after exceeding 135°C was defined as 0 minutes of the thermal stability test time. Subsequently, kneading was continued while adjusting the rotation speed so that the temperature of the Banbury mixer remained within the range of 140°C ± 5°C. Note that if the temperature does not rise to 135°C or higher even when the rotation speed is increased, the temperature at the time of adding the conjugated diene polymer or the Banbury mixer may be heated to increase the temperature. The rotation was stopped 30 minutes, 60 minutes, and 90 minutes after the start of the thermal stability test, and 1 g of each sample was taken. After sampling was completed, the rotation was started again. 0.5 g of each sample was placed in a vial containing 10 ml of tetrahydrofuran and dissolved by shaking for 3 hours. If no insoluble components were found by visual inspection after that, no gel had been formed and the result was rated as "O", and if any insoluble components were found, the result was rated as "X". This test was designed to verify the risk of gel formation during kneading when producing a conjugated diene polymer or preparing a compound. If the result of this test was "X", the productivity was very poor due to the high risk of gel formation and the product was not suitable for industrial use. It was determined that a rating of "O" was necessary for practical use.

[0197] [Thermal Stability Test (High Temperature)] The same samples and equipment as in the thermal stability test (low temperature) were used, but the temperature conditions were changed as follows. 50 g of a conjugated diene polymer was added to a Banbury mixer heated to 90°C and kneaded at 10 rpm for 4 minutes. The rotation speed was then increased so that the temperature of the Banbury mixer exceeded 155°C within 1 to 6 minutes. The time when the temperature exceeded 155°C was designated as 0 minutes of the thermal stability test, and kneading was continued. Subsequently, kneading was continued while adjusting the rotation speed so that the temperature of the Banbury mixer fell within the range of 160°C ± 5°C. The temperature at the time of adding the conjugated diene polymer may be increased, or the Banbury mixer may be heated or raised. The rotation was stopped 30, 60, and 90 minutes after the start of the thermal stability test, and 1 g of each sample was sampled. After sampling was completed, the rotation was restarted. 0.5 g of each sample was placed in a vial containing 10 ml of tetrahydrofuran and dissolved by shaking for 3 hours. If there was no insoluble component when visually inspected, it was judged that no gel had been formed and was rated as ◯, and if there was an insoluble component, it was rated as ×. This test, like the test at low temperature (140°C ± 5°C) described above, was a test to verify the risk of gel formation during production of a conjugated diene polymer or kneading during compound preparation, and a rating of ◯ indicates good productivity and is preferable. However, in this test, even in the case of ×, it was judged that production was possible in actual production by sufficiently controlling the temperature.

[0198] [Preparation of Multifunctional Polymerization Initiator] The multifunctional polymerization initiator used in this example was prepared by the following method. A 10 L autoclave equipped with a stirrer and jacket was used as a reactor. Cyclohexane and n-butyllithium were added to the reactor, followed by cleaning and nitrogen substitution. 4583 g of cyclohexane, 10.3 g of divinylbenzene, and 450 g of 1,3-butadiene were added. The temperature inside the reactor was maintained at 40°C, and then 530 mmol of n-butyllithium was added and reacted for 90 minutes, after which the temperature inside the reactor was raised to 85°C. The reactor was then allowed to cool for 2 hours to prepare a multifunctional catalyst. The mixture was then allowed to stand at room temperature for 24 hours before use in the polymerization reaction. The divinylbenzene used was a divinylbenzene mixture containing m-divinylbenzene, p-divinylbenzene, ethylbenzene, and the like, with a divinylbenzene concentration of 57% by mass. The above amount of divinylbenzene added refers to the amount of divinylbenzene itself added. When a polyfunctional initiator is used as the polymerization initiator, the amount added is determined in terms of n-butyllithium.

[0199] [Production of Conjugated Diene Polymer] (Example 1) Polymer 1 As shown in Table 1, a 40 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 3,000 g of 1,3-butadiene, from which impurities had been removed in advance, 21,000 g of cyclohexane, and 0.16 mol of tetrahydrofuran (THF) as a polar substance were charged into the reactor, and the internal temperature of the reactor was maintained at 42°C. 15.9 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the polymerization reaction started, the temperature inside the reactor rose due to heat generated by the polymerization, and the final temperature inside the reactor was 83°C. To this polymer solution, 0.64 mmol of 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (Compound 1) was added as a modifying agent, and after reacting for 3 minutes, 12.7 mmol of 1,3-dimethyl-2-imidazolidinone (Compound 2) was added as a modifying agent and reacted for 5 minutes. Subsequently, 15 mol of water was added as a reaction terminator. To the resulting polymer solution, 21.0 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (Stabilizer 1) and 9.0 g of 4,6-bis(octylthiomethyl)-o-cresol (Stabilizer 2) were added as antioxidants, and the conjugated diene polymer solution was then added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain Polymer 1. The resulting Polymer 1 was analyzed by the above-mentioned methods, and the analytical results are shown in Table 3.

[0200] (Examples 2 to 5, 13 to 17, Comparative Examples 1, 4 to 7) As shown in Tables 1 and 2, conjugated diene polymers (polymers 2 to 5, 13 to 17, 20, and 23 to 26) were obtained in the same manner as in Example 1, except that the type and amount of modifier added were changed. A stabilizer shown in Tables 1 and 2 was added to the resulting conjugated diene polymer solution, and the resulting conjugated diene polymer solution was then dropped into warm water to remove the solvent. The resulting solution was then dried in a dryer to obtain conjugated diene polymer (polymers 2 to 5, 13 to 17, 20, and 23 to 26) compositions. In Tables 1 and 2, when Compound 3, Compound 4, Compound 7, or Compound 8 is used, it was used in place of Compound 1, and when Compound 5 or Compound 6 is used, it was used in place of Compound 2. In Example 16, dibutylhydroxytoluene (stabilizer 3) was used as the stabilizer. The resulting polymers were analyzed by the above-described methods, and the analytical results are shown in Tables 3 and 4.

[0201] (Example 6) Polymer 6 As shown in Table 1, a 40 L internal volume, temperature-controllable autoclave equipped with a stirrer and jacket was used as a reactor. 3,000 g of 1,3-butadiene, from which impurities had been removed in advance, 21,000 g of cyclohexane, and 0.16 mol of tetrahydrofuran (THF) as a polar substance were charged into the reactor, and the internal temperature of the reactor was maintained at 42°C. As a polymerization initiator, 15.9 mmol of the aforementioned multifunctional initiator, calculated as n-butyllithium, was supplied to the reactor. After the polymerization reaction began, the temperature inside the reactor rose due to heat generated by the polymerization, and the final temperature inside the reactor was 82°C. To this polymer solution, 15.1 mmol of 1,3-dimethyl-2-imidazolidinone (Compound 2) was added, and the reaction was allowed to proceed for 5 minutes. Thereafter, 16 mol of water was added as a reaction terminator. To the resulting polymer solution, 21.0 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)-propionate (stabilizer 1) and 9.0 g of 4,6-bis(octylthiomethyl)-o-cresol (stabilizer 2) were added as antioxidants, and the conjugated diene polymer solution was then added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain polymer 6. The resulting polymer 6 was analyzed by the above-mentioned methods, and the results are shown in Table 3.

[0202] (Example 7) Polymer 7 As shown in Table 1, a 40 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 2,940 g of 1,3-butadiene, from which impurities had been removed in advance, 21,000 g of cyclohexane, and 0.16 mol of tetrahydrofuran (THF) as a polar substance were charged into the reactor, and the internal temperature of the reactor was maintained at 42°C. 15.9 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the polymerization reaction started, the temperature inside the reactor rose due to heat generated by the polymerization, and reached 76°C. 4.8 mmol of 2-bis(2-oxolanyl)propane (BOP) was added to this polymer solution, and immediately thereafter 60 g of styrene was added and the reaction was carried out for 2 minutes. Subsequently, 0.8 mmol of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (compound 4) was added and allowed to react for 2 minutes, after which 12.7 mmol of 1,3-dimethyl-2-imidazolidinone (compound 2) was added and allowed to react for 5 minutes. Subsequently, 15 mol of water was added as a reaction terminator. To the resulting polymer solution, 21.0 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (stabilizer 1) and 9.0 g of 4,6-bis(octylthiomethyl)-o-cresol (stabilizer 2) were added as antioxidants, and the conjugated diene polymer solution was then added dropwise to warm water to remove the solvent. The resulting polymer was then dried in a dryer to obtain polymer 7. The analytical results of the resulting polymer 7, which was analyzed by the above-mentioned methods, are shown in Table 3.

[0203] (Examples 8 to 10, 12, 18, 19, Comparative Example 2) Polymers 8 to 10, 12, 18, 19, 21 As shown in Tables 1 and 2, each conjugated diene polymer was obtained in the same manner as in Example 7, except that the amount of styrene added and the type and amount of modifier added were changed. However, in Example 9, 15.9 mmol of piperidine was added at the same time as tetrahydrofuran. A stabilizer shown in Tables 1 and 2 was added to each of the obtained conjugated diene polymer solutions, and then the conjugated diene polymer solutions were added dropwise to warm water to remove the solvent. The solutions were then dried in a dryer to obtain conjugated diene polymer (polymers 8 to 10, 12, 18, 19, 21) compositions. In Tables 1 and 2, when Compound 3, Compound 4, Compound 7, or Compound 8 was used, it was used in place of Compound 1, and when Compound 5 or Compound 6 was used, it was used in place of Compound 2. The results of analyzing the obtained polymers using the above-mentioned methods are shown in Tables 3 and 4.

[0204] (Example 11) Polymer 11 As shown in Table 1, a 40 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor, and 2,850 g of 1,3-butadiene, 150 g of styrene, 21,000 g of cyclohexane, and 0.16 mol of tetrahydrofuran (THF) and 4.8 mmol of 2-bis(2-oxolanyl)propane (BOP) as polar substances were placed in the reactor, and the internal temperature of the reactor was maintained at 42°C. 15.9 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the polymerization reaction started, the temperature inside the reactor rose due to heat generated by the polymerization, and the temperature inside the reactor reached 79°C. To this polymer solution, 0.8 mmol of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (compound 4) was added and allowed to react for 2 minutes. Then, 12.7 mmol of 1,3-dimethyl-2-imidazolidinone (compound 2) was added and allowed to react for 5 minutes. Subsequently, 15 mol of water was added as a reaction terminator. To the resulting polymer solution, 21.0 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (stabilizer 1) and 9.0 g of 4,6-bis(octylthiomethyl)-o-cresol (stabilizer 2) were added as antioxidants. The conjugated diene polymer solution was then added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain polymer 11. The resulting polymer 11 was analyzed by the above-described methods, and the analytical results are shown in Table 3.

[0205] (Comparative Example 3) Polymer 22 As shown in Table 2, a 40 L internal volume, temperature-controllable autoclave equipped with a stirrer and a jacket was used as a reactor. 3,000 g of 1,3-butadiene, from which impurities had been removed in advance, 21,000 g of cyclohexane, and 0.16 mol of tetrahydrofuran (THF) and 4.0 mmol of 2-bis(2-oxolanyl)propane (BOP) as polar substances were charged into the reactor, and the internal temperature of the reactor was maintained at 40°C. 15.9 mmol of n-butyllithium was supplied to the reactor as a polymerization initiator. After the polymerization reaction started, the temperature inside the reactor rose due to heat generated by the polymerization, and the final temperature inside the reactor was 85°C. To this polymer solution, 0.8 mmol of 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane (Compound 1) was added, and after a 3-minute reaction, 11.9 mol of 1,3-dimethyl-2-imidazolidinone (Compound 2) was added, and the reaction was continued for 5 minutes. Subsequently, 15 mol of water was added as a reaction terminator. To the resulting polymer solution, 21.0 g of n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate (Stabilizer 1) and 9.0 g of 4,6-bis(octylthiomethyl)-o-cresol (Stabilizer 2) were added as antioxidants. The conjugated diene polymer solution was then added dropwise to warm water to remove the solvent, followed by drying in a dryer to obtain Polymer 22. The resulting Polymer 22 was analyzed by the above-described methods, and the analytical results are shown in Table 4.

[0206]

[0207]

[0208]

[0209]

[0210] The symbols in Tables 1 and 2 below are as follows: THF: Tetrahydrofuran BOP: 2,2-bis(2-oxolanyl)propane Compound 1: 2,2-dimethoxy-1-(3-trimethoxysilylpropyl)-1-aza-2-silacyclopentane Compound 2: 1,3-dimethyl-2-imidazolidinone Compound 3: Tetramethoxysilane Compound 4: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane Compound 5: N-methylpyrrolidone Compound 6: N-phenylpyrrolidone Compound 7: 3-(4-methylpiperazin-1-yl)propyltriethoxysilane Stabilizer 1: n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate Stabilizer 2: 4,6-bis(octylthiomethyl)-o-cresol Stabilizer 3: dibutylhydroxytoluene

[0211] [Application Examples 1 to 19, Application Comparative Examples 1 to 8] Conjugated diene polymers 1 to 26 shown in Tables 3 and 4 and high-cis-butadiene rubber (UBEPOL BR150, manufactured by UBE) were used as raw rubbers, and conjugated diene polymer compositions containing the respective raw rubbers were obtained according to the formulations shown below. When the conjugated diene polymer of Example 1 was used, it was designated Application Example 1, and when the conjugated diene polymer of Comparative Example 1 was used, it was designated Application Comparative Example 1. Similarly, the Example numbers and Comparative Example numbers correspond to the Application Example numbers and Comparative Example numbers, respectively. The composition using high-cis-butadiene rubber was designated Application Comparative Example 8.

[0212] (Conjugated diene polymer composition) Raw rubber (conjugated diene polymer 1-25, high-cis butadiene rubber): 100.0 parts by mass Carbon black (Tokai Carbon Co., Ltd., SEAST SO (N550)): 50.0 parts by mass Naphthenic oil (Idemitsu Kosan Co., Ltd., DIANA PROCESS NM-280): 10.0 parts by mass Zinc oxide: 5.0 parts by mass Stearic acid: 1.0 part by mass Antioxidant (Nocrac 6C): 2.0 parts by mass Antioxidant (Nocrac MB): 1.0 part by mass Wax (Ouchi Shinko Chemical Co., Ltd., Sunnock N): 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: 175.0 parts by mass

[0213] The above materials were kneaded by the following method to obtain a conjugated diene polymer composition. Using an internal mixer (capacity: 0.3 L) equipped with a temperature control device, the raw rubber, filler (carbon black), oil (naphthenic oil), wax (Sunnoc N), zinc oxide, stearic acid, and antioxidants (Nocrac 6C, Nocrac MB) were kneaded in the first stage at a filling rate of 65% and rotor rotation speeds of 50 / 57 rpm. The temperature of the internal mixer was controlled, and the discharge temperature (compound) was 150°C to obtain a conjugated diene polymer composition. After cooling, the mixture was kneaded in the second stage using an open roll set at 70°C, adding sulfur and a vulcanization accelerator. Subsequently, sheets of 2 mm and 3 mm thickness were molded and vulcanized in a vulcanization press at 160°C for 20 minutes. For tensile property testing, test specimens were prepared from the 2 mm thick vulcanized sheets using a punching machine. The compression set and dynamic magnification were measured by vulcanization using a mold so that each sample had a diameter of 29 mm and a thickness of 12.6 mm. After vulcanization, the physical properties of the conjugated diene polymer composition were measured. The results of the physical property measurements are shown in Tables 5 and 6. After vulcanization as described above, the physical properties of the vulcanized conjugated diene polymer composition were measured by the following methods.

[0214] (1) Processability: Mooney Viscosity of Composition) A portion of the kneaded conjugated diene polymer composition was taken out before molding, and the Mooney viscosity was measured. Using a Mooney viscometer, the composition was preheated at 100°C for 1 minute, and then the rotor was rotated at 2 revolutions per minute for 4 minutes, and the viscosity was measured according to JIS K6300-1. When the Mooney viscosity of the composition was 40 or more and 110 or less, it was determined that the processability was acceptable for practical use, and was rated as ○. On the other hand, when it was less than 40, the composition was prone to adhesion to equipment, and the processability deteriorated. When it exceeded 110, the composition had poor cohesion during kneading and was prone to tearing when made into a sheet, and it was determined that the processability was poor and not preferable for practical use, and was rated as ×.

[0215] ((2) Tensile Properties) The tensile strength and elongation at 23°C were measured in accordance with the tensile testing method of JIS K6251. The product of the tensile strength and elongation at 23°C was taken as the tensile property. Higher values ​​of the tensile property are preferable. Tables 5 and 6 show relative values ​​where Application Comparative Example 8 is used as the standard and the measured value of Application Comparative Example 8 is set to 100. The higher the relative value, the better. If the difference from Application Comparative Example is within 5%, it is equivalent, and if it is more than 5% and is improved, it is preferable. On the other hand, if the deterioration is more than 5% and less than 10%, it is at a level that is not problematic in practical use, but if it is worsened by more than 10%, it is judged to be undesirable.

[0216] ((3) Dynamic Magnification Ratio) In accordance with JIS K6385, the static spring constant (static spring constant) and dynamic spring constant (dynamic spring constant) of the crosslinked rubber composition were measured, and the dynamic magnification ratio (dynamic spring constant / static spring constant) was calculated. The measuring device used was an ACUMEN3 manufactured by MTS. The lower the dynamic magnification ratio, the better. Tables 5 and 6 show the relative values ​​when Application Comparative Example 8 is used as the standard and the measured value of Application Comparative Example 8 is set to 100. The higher the relative value, the better. If the improvement range was more than 0% and within 5%, it was considered to be the same, and if it was improved by more than 5%, it was an improvement compared to the standard, an improvement of 15% or more is more preferable, and an improvement of 25% or more is even more preferable. If the improvement range relative to Application Comparative Example 8 was 5% or less, it was determined that the improvement effect was insufficient.

[0217] ((4) Compression Set) In accordance with JIS K6262, compression set was measured after heating for 72 hours in an environment of 120°C. The smaller the compression set value, the better the result. Tables 5 and 6 show relative values ​​when the measured value of Application Comparative Example 8 is set to 100. The higher the relative value, the better the result. If the difference from Application Comparative Example 8 is within 5%, the result is equivalent, and if it is more than 5% and has improved, it is preferable. On the other hand, if the deterioration is more than 5% and less than 10%, it is at a level that does not pose a problem in practical use, but if it is more than 10% and has improved, it is judged to be undesirable.

[0218]

[0219]

[0220] It was found that the conjugated diene polymers obtained in Examples 1 to 19 and the conjugated diene polymer compositions of Application Examples 1 to 19 were excellent in practically sufficient tensile strength, compression set, and dynamic magnification while maintaining the cold flow properties of the bale, production stability, and processability when obtaining a compound, compared to the conjugated diene polymers obtained in Comparative Examples 1 to 7 or the high-cis-butadiene rubber used as a reference product, and the conjugated diene polymer compositions of Application Comparative Examples 1 to 8.

[0221] The conjugated diene polymer and the conjugated diene polymer composition of the present embodiment have industrial applicability as vibration-proof rubber, vibration-damping rubber materials, vibration-isolating rubber, tires, packings and gaskets, sealing materials, conveyor belts, power transmission belts, shoe outsoles and shoe midsoles, automobile weather strips, glass runs, trunk lids, railway vehicle components, aircraft components, waterproof sheets, engine mounts, motor mounts, industrial hoses, air springs, rubber gloves, medical and sanitary products, hoses for industrial and various uses, battery cases, adhesives, electric wire coatings, window frame rubber, rubber rolls, rubber rollers for office automation equipment and spinning, etc., keypads, keyboard covers, underwater goggles, swimming caps, container bags, marine-related parts, indoor flooring materials, artificial muscle materials, other vibration-reducing materials, materials for various industrial products, and the like.

Claims

1. A conjugated diene polymer comprising structural units derived from a conjugated diene compound, wherein the content of structural units derived from an aromatic vinyl compound is 7 mass% or less, the amount of 1,2-vinyl bonds in the structural units derived from the conjugated diene compound is 8 mol% or more and 22 mol% or less, the modification rate is 30% or more and 99% or less, the Mooney viscosity at 100°C is 25 or more and 130 or less, the Mooney stress relaxation at 100°C is 0.30 to 0.85, and the total content of silicon and tin is 50 ppm or less.

2. The conjugated diene polymer according to claim 1, which has a glass transition temperature of -86°C or lower and -98°C or higher as measured by differential scanning calorimetry (DSC).

3. The conjugated diene polymer according to claim 1, wherein a molecular weight distribution curve measured by gel permeation chromatography (GPC) has two or more peaks with a peak area of ​​5% or more, and when the peak with the largest peak area is designated as Peak A, Peak A is located on the lowest molecular weight side of the peaks with an area of ​​5% or more, and the area of ​​Peak A is 60% or more and 95% or less.

4. The conjugated diene polymer according to claim 1, wherein a molecular weight distribution curve measured by gel permeation chromatography (GPC) has two or more peaks with a peak area of ​​5% or more, and when the peak with the largest peak area is designated as Peak A, Peak A is located on the lowest molecular weight side of the peaks with an area of ​​5% or more, and the area of ​​Peak A is 80% or more and 95% or less.

5. The conjugated diene polymer according to claim 1, wherein a molecular weight distribution curve measured by gel permeation chromatography (GPC) has two or more peaks with a peak area of ​​5% or more, and when the peak with the largest peak area is designated as Peak A, Peak A is located on the lowest molecular weight side of the peaks with an area of ​​5% or more, and the modification rate of Peak A is 50% or more but 98% or less.

6. The conjugated diene polymer according to claim 1, wherein the tin content is 30 ppm or less.

7. A conjugated diene polymer composition comprising: 100 parts by mass of the conjugated diene polymer according to claim 1; and 0.55 to 1.8 parts by mass of a hindered phenol antioxidant.

8. A conjugated diene polymer composition comprising: 100 parts by mass of the conjugated diene polymer according to claim 1; 0.1 part by mass or more and 1.0 part by mass or less of a sulfur-containing hindered phenol-based antioxidant; and 0.35 part by mass or more and 1.0 part by mass or less of a sulfur-free hindered phenol-based antioxidant.

9. A conjugated diene polymer composition comprising: 100 parts by mass of a rubber component; and 10 to 300 parts by mass of a filler, wherein the rubber component contains 10% by mass or more of the conjugated diene polymer according to claim 1; and the filler contains 40% by mass or more of carbon black.

10. A vibration-proof rubber comprising the conjugated diene polymer or crosslinked product thereof according to any one of claims 1 to 6, or the conjugated diene polymer composition or crosslinked product thereof according to any one of claims 7 to 9.

11. A power transmission belt comprising the conjugated diene polymer or crosslinked product thereof according to any one of claims 1 to 6, or the conjugated diene polymer composition or crosslinked product thereof according to any one of claims 7 to 9.

12. A conveyor belt comprising the conjugated diene polymer or crosslinked product thereof according to any one of claims 1 to 6, or the conjugated diene polymer composition or crosslinked product thereof according to any one of claims 7 to 9.

13. A shoe sole comprising the conjugated diene polymer or crosslinked product thereof according to any one of claims 1 to 6, or the conjugated diene polymer composition or crosslinked product thereof according to any one of claims 7 to 9.

14. An industrial material comprising the conjugated diene polymer or crosslinked product thereof according to any one of claims 1 to 6, or the conjugated diene polymer composition or crosslinked product thereof according to any one of claims 7 to 9.

15. A tire comprising the conjugated diene polymer or crosslinked product thereof according to any one of claims 1 to 6, or the conjugated diene polymer composition or crosslinked product thereof according to any one of claims 7 to 9.

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