Conjugated diene polymer as well as preparation method and application thereof

Abstract

The invention relates to the field of rubber synthesis, in particular to a conjugated diene polymer as well as a preparation method and application thereof. According to the conjugated diene polymer provided by the invention, the proportion of molecules with the molecular rotation radius Rg smaller than 5nm in the conjugated diene polymer is small, and the conjugated diene polymer can be better physically wound and effectively adsorbed on the surface of a filler to form a strong interface layer, so that the dispersity of the filler is enhanced; good interaction interface strength between the polymer and the filler is achieved; the density of cross-linking points formed in the vulcanization stage is improved, and the strength is improved; in conclusion, when the conjugated diene polymer provided by the invention is applied to rubber, the rubber has relatively high wear resistance, high strength, rolling resistance and wet skid resistance.

Description

Technical Field

[0001] This invention relates to the field of rubber synthesis, specifically to a conjugated diene polymer, its preparation method, and its application. Background Technology

[0002] To meet the demand for reduced fuel consumption in automobiles, developing tire rubber composites that combine low rolling resistance, excellent wet skid resistance, high wear resistance, and good tensile properties has become a key technological challenge that the industry urgently needs to address. However, existing material systems often struggle to simultaneously optimize these properties, particularly exhibiting a significant contradiction in balancing low rolling resistance and high wet skid resistance.

[0003] Anionic polymerization is used to prepare solution-polymerized butadiene-styrene copolymers or polybutadiene. Because it allows for precise control of molecular weight, molecular weight distribution, chain microstructure, and block sequence, it is considered a key method for solving the aforementioned problems. However, polymer materials prepared using existing technologies are difficult to apply to rubber applications while simultaneously achieving high wear resistance, high strength, rolling resistance, and anti-slip properties. Summary of the Invention

[0004] This invention provides a conjugated diene polymer, its preparation method, and its application, in order to solve the problem that polymer materials prepared by existing technologies are difficult to apply to rubber to achieve high wear resistance, high strength, rolling resistance, and anti-slip properties.

[0005] In a first aspect, the present invention provides a conjugated diene polymer having the following structure:

[0006] Where a, b, and c are all integers, and a / (a+b+c)=0.05-0.95, b / (a+b+c)=0.05-0.95, c / (a+b+c)=0.05-0.95, and n is a positive integer from 1 to 4.

[0007] Wherein, R1 is selected from the chain-end groups retained after the initiator reaction; R2 is selected from the functional groups in the coupling agent that are retained after a chemical reaction. Furthermore, conjugated diene polymers satisfy the following conditions: (1) When the number of peaks in the gel chromatography-permeation chromatography molecular weight distribution curve of the conjugated diene polymer is singular or plural, the molecular weight of the lowest peak is between 1.01 and 1.2. (2) When the number of peaks in the gel chromatography-permeation chromatography molecular weight distribution curve of the conjugated diene polymer is singular or plural, the peak molecular weight of the lowest peak is 50,000 g / mol to 2,000,000 g / mol. (3) The total mass of molecules with a molecular rotation radius Rg of less than 5 nm in the conjugated diene polymer accounts for less than 1% of the total molecular mass, wherein the molecular rotation radius Rg is determined by GPC-light scattering method.

[0008] Current technologies do not identify or control the impact of these low molecular weight components on performance during the polymer-filler composite stage. Research has found that not all low molecular weight components are equally harmful; their degree of harm primarily depends on their molecular size (radius of gyration, Rg). When the polymer's radius of gyration, Rg, is much smaller than the filler particle size (e.g., approximately 15-20 nm for silica), its molecular chain segment length is insufficient to effectively bridge and entangle multiple adjacent filler particles simultaneously, thus failing to participate in the formation of a robust polymer-filler three-dimensional network. These molecules essentially constitute "functionally ineffective molecules."

[0009] The presence of these "functionally ineffective molecules" has multiple negative effects: (1) Their molecular size is much smaller than that of the filler particles, and they cannot form a strong interfacial layer on the filler surface through physical entanglement and effective chain segment adsorption like polymers. In the composite stage, they isolate the contact between high molecular weight polymers and fillers, resulting in poor filler dispersibility and severely weakening the interfacial strength of the polymer-filler interaction; (2) In the vulcanization stage, the crosslinking points they form have low density and weak strength; (3) Under dynamic use conditions, such weak interfaces and weak crosslinking points are prone to damage and reconstruction, resulting in irreversible slippage between molecular chains, generating extremely high energy dissipation, which macroscopically manifests as increased rolling resistance and internal heat, while wear resistance and mechanical properties decrease.

[0010] The material provided by this invention has a molecular rotation radius Rg of less than 5 nm, and the proportion of molecules with a molecular rotation radius Rg of less than 1% of the total number of molecules is less than 1%. This allows the obtained conjugated diene polymer to achieve a balance of wear resistance, high strength, rolling resistance, and anti-slip properties in applications.

[0011] In one alternative embodiment, the initiator is selected from organolithium.

[0012] In one optional embodiment, the initiator structure is LiR1; R1 is selected from C1-C6 alkyl, C3-C10 cycloalkyl, C3-C10 nitrogen-containing heterocycloalkyl, C6-C12 aryl, C3-C12 heteroaryl; and C2-C10 alkylamine.

[0013] In one alternative embodiment, R1 is selected from at least one of ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, n-pentyl, n-hexyl, cyclohexyl, phenyl, benzyl, naphthyl, piperidinyl, hexamethyleneimino, and diethylamino.

[0014] In one alternative embodiment, the coupling agent comprises a silane coupling agent.

[0015] In one optional embodiment, the silane coupling agent comprises at least one of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, and silicon tetrachloride. In one optional implementation, R2 is selected from R2. , , , , , , At least one of them, Indicates a connection key.

[0016] In one alternative embodiment, the ratio of butadiene to styrene is 0.05-0.95:0.05-0.95.

[0017] Secondly, the present invention also provides a method for preparing a conjugated diene polymer, comprising the following steps: S1: Butadiene and styrene are added to a hydrocarbon solvent under stirring conditions, and an initiator is added under stirring conditions to carry out the reaction and obtain an active polymer; S2: The active polymer obtained in S1 is reacted with a coupling agent to obtain the conjugated diene polymer; The preparation method needs to meet the following conditions: a) The total time from the start of adding the initiator to its completion is less than 2 minutes; b) During the initiator feeding and subsequent reaction process, the volumetric work per unit volume of stirring is greater than or equal to 0.5 kW / m³. 3 ; c) The initiation temperature when the initiator is added is 0-25℃; d) From the time the initiator feeding is completed, the relative deviation of the initiator concentration in any region of the system from the average initiator concentration of the system shall not exceed 5% for a period of time not exceeding 5 minutes; In existing anionic polymerization processes, a certain amount of low-molecular-weight "functionally ineffective molecules" inevitably remain in the product. Traditional research has focused on purifying the raw materials to avoid terminating the polymerization reaction and thus reducing the formation of low-molecular-weight components. However, the inventors have discovered that in large-scale anionic polymerization, the dispersion efficiency of the initiator in the system is lower than the initiation efficiency and impurity removal efficiency, which is a key factor leading to an increased proportion of low-molecular-weight components in the polymer molecules. If the initiator is added for too long, the initiation temperature is too high, or the total mixing time is too long, it will lead to asynchrony in the initiation process. Some of the already initiated active polymers will react with impurities in the system during mixing, generating a large number of "functionally ineffective molecules" with small radii of rotation. Therefore, by controlling the initiator addition conditions, the proportion of "functionally ineffective molecules" with small radii of rotation can be significantly reduced.

[0018] In one optional embodiment, the hydrocarbon solvent is selected from at least one of C5-C8 chain alkanes, C5-C8 cycloalkanes, and C6-C12 aromatic hydrocarbons.

[0019] In one optional embodiment, the hydrocarbon solvent is selected from one or a mixture of several of cyclohexane, n-hexane, cyclopentane, pentane, heptane, and benzene; In one alternative embodiment, the initiator is selected from organolithium initiators.

[0020] In one optional embodiment, the initiator is selected from at least one of lithium ethyl, lithium n-propyl, lithium isopropyl, lithium n-butyl, lithium sec-butyl, lithium n-pentyl, lithium n-hexyl, lithium cyclohexyl, lithium phenyl, lithium benzyl, lithium naphthyl, lithium piperidinium, lithium hexamethyleneimine, and lithium diethylamine. In one optional embodiment, the mass ratio of the hydrocarbon solvent, butadiene, styrene, and initiator is 1500-375000:20-30000:20-30000:1.

[0021] In one optional embodiment, in step S1, after adding butadiene and styrene and before adding the initiator, a reaction regulator is also added; In one alternative embodiment, the reaction regulator is selected from one or more of C3-C10 ethers and C3-C10 amines.

[0022] In one alternative embodiment, the structure modifier is selected from one or more of diethyl ether, dibutyl ether, tetrahydrofuran, dioxane, triethylamine, and tetramethylethylenediamine.

[0023] In one optional embodiment, the mass ratio of the reaction regulator to the hydrocarbon solvent is 1:(200-600). In one optional embodiment, the reaction temperature in step S1 is 40-120°C; the reaction time is 0.1-4h.

[0024] In one optional embodiment, in step S2, the mass ratio of the active polymer prepared in S1 to the coupling agent is 300-1500:1. In one alternative embodiment, the coupling agent comprises a silane coupling agent; In one optional embodiment, the silane coupling agent comprises at least one of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, and silicon tetrachloride. In one alternative implementation, R2 is selected from: , , , , , , At least one of them, Indicates a connection key.

[0025] Thirdly, the present invention also provides a rubber composition comprising the conjugated diene polymer described above or the conjugated diene polymer prepared by the preparation method described above; In one alternative embodiment, the rubber composition further includes fillers.

[0026] Fourthly, the present invention also provides a method for preparing the rubber composition described above, comprising the following steps: mixing and vulcanizing a conjugated diene polymer with a filler to obtain the rubber composition.

[0027] The technical solution of this invention has the following advantages: 1. The present invention provides a conjugated diene polymer, wherein the conjugated diene polymer satisfies the following conditions: (1) when the number of peaks in the gel chromatography-permeation chromatography molecular weight distribution curve of the conjugated diene polymer is singular or plural, the molecular weight of the lowest peak is between 1.01 and 1.2; (2) when the number of peaks in the gel chromatography-permeation chromatography molecular weight distribution curve of the conjugated diene polymer is singular or plural, the molecular weight of the lowest peak is between 50,000 g / mol and 2,000,000 g / mol; (3) the total mass of molecules with a molecular rotation radius Rg of less than 5 nm in the conjugated diene polymer accounts for less than 1% of the total mass of all molecules, wherein the molecular rotation radius Rg is determined by GPC-light scattering method.

[0028] Among the conjugated diene polymers possessing the above properties, the proportion of molecules with a molecular rotation radius Rg less than 5 nm is relatively small. Conjugated diene polymers can better physically entangle and effectively adsorb onto the filler surface to form a strong interfacial layer, thereby enhancing the filler's dispersibility and exhibiting better polymer-filler interfacial strength. Furthermore, the density and strength of crosslinking points formed during the vulcanization stage are increased. In summary, the conjugated diene polymers provided in this application, when applied to rubber, can enable the rubber to possess high wear resistance, high strength, rolling resistance, and anti-slip properties.

[0029] 2. The present invention provides a method for preparing conjugated diene polymers. By restricting the addition conditions of raw materials in the preparation method, the total mass of molecules with a molecular rotation radius Rg less than 5 nm in the prepared conjugated diene polymer accounts for less than 1% of the total mass of all molecules. The reduction of molecules with a molecular rotation radius Rg less than 5 nm can enable the conjugated diene polymer to be applied to rubber, so that the rubber has high wear resistance, high strength, rolling resistance, and anti-slip properties. Detailed Implementation

[0030] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0031] Unless otherwise specified, the experimental steps or conditions in the examples were performed in accordance with conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0032] Main raw material sources: Butadiene: Yantai Mingju Gas Co., Ltd., purity > 99%, CAS No. 106-99-0; Styrene: Shandong Zhengxing New Materials Co., Ltd., purity > 99%, CAS No. 100-42-5; n-Butyllithium: Shaoxing Shangyu Hualun Chemical Co., Ltd., purity 1.6M, CAS No. 109-72-8; Cyclohexane: Yangzhou Jinshi Chemical Yangzi Co., Ltd., purity > 99%, CAS No. 110-82-7; Tetrahydrofuran: Jinan Hongli Chemical Co., Ltd., purity > 99%, CAS No. 109-99-9; Dibutyl ether: Wuxi Yangshi Chemical Co., Ltd., purity > 99%, CAS No. 142-96-1; Triethylamine: Shandong Hongyuan Chemical Technology Co., Ltd., purity > 99%, CAS No. 121-44-8; Dimethyldimethoxysilane: Zhejiang Jiancheng New Material Co., Ltd., purity >99%, CAS No. 1112-39-6; γ-aminopropyltriethoxysilane: Shandong Silicon Science New Materials Co., Ltd., purity > 99%, CAS No. 919-30-2; Silicon tetrachloride: Zhejiang Xin'an Chemical Group Co., Ltd., purity > 99%, CAS No. 10026-04-7.

[0033] Unless otherwise specified, all other raw materials and reagents can be purchased through ordinary commercial channels.

[0034] The analytical and evaluation methods involved in the examples or comparative examples are as follows: The method for calculating the work per unit volume of the reactor is P=Np*ρ*n 3 *d 5 / V, where Np is the power constant, which can be obtained from the datasheet provided by the agitator supplier. ρ is the average density of the reaction system, in kg / m³. 3 n is the stirring speed, in revolutions per second. d is the impeller diameter, in meters (m). V is the reaction volume, in cubic meters (m³). 3 .

[0035] The test method for ensuring that the relative deviation of the initiator concentration in any region of the system from the average initiator concentration is ≤5% within 5 minutes after the initiator is added is as follows: Add the same volume of solvent to the reactor. Under the same stirring parameters as the reaction, add a 0.1M methanol solution of lithium hydroxide through the initiator inlet using the same method as adding the initiator. Collect conductivity data over time at different locations inside the reactor using a conductivity probe. The collected signals are transmitted in real time to the data acquisition system, which records the conductivity-time curve at a frequency of at least 10 Hz to obtain the initial response curve. Analyze the collected response curves. When the concentration at time t reaches 95% of the final average concentration, that time is considered the total mixing time t.

[0036] Example 1 This embodiment provides a method for preparing conjugated diene polymers, comprising the following steps: Add 8500 kg of cyclohexane, 375 kg of styrene, and 1125 kg of butadiene to a 20000 L reactor. Add 20 kg of tetrahydrofuran and maintain the reactor temperature at 10 °C. Add 5 kg of n-butyllithium solution to the reactor to initiate the reaction over 30 seconds. After polymerization at 60 °C for 80 min, add 1.31 kg of silicon tetrachloride and react for 10 min. Remove the solvent, unreacted monomers, and tetrahydrofuran to obtain polymer A1.

[0037] The 20000L reactor has a vessel diameter of 2000mm, uses a 3-layer A320 impeller with a blade diameter of 1000mm, and has a stirring speed of 120rpm. The calculated work per unit volume of the reaction system is 1.62kW / m³. 3 The total mixing time under this stirring condition was 115 seconds.

[0038] Example 2 This embodiment provides a method for preparing conjugated diene polymers, comprising the following steps: Add 8500 kg of cyclohexane, 375 kg of styrene, and 1125 kg of butadiene to a 20000 L reactor; add 20 kg of dibutyl ether, and control the reactor temperature to 10 °C. Add 8.28 kg of piperidinium solution to the reactor to initiate the reaction over 90 s. After polymerization for 80 min, add 1.85 kg of dimethyldimethoxysilane and react for 20 min. Remove the solvent, unreacted monomer, and dibutyl ether to obtain conjugated diene polymer A2.

[0039]

[0040] The 20000L reactor has a vessel diameter of 2000mm, uses a 3-layer A320 impeller with a blade diameter of 1000mm, and has a stirring speed of 120rpm. The calculated work per unit volume of the reaction system is 1.62kW / m³. 3 The total mixing time under this stirring condition was 115 seconds.

[0041] Example 3 This embodiment provides a method for preparing conjugated diene polymers, comprising the following steps: Add 8500 kg of cyclopentane, 375 kg of styrene, and 1125 kg of butadiene to a 20000 L reactor. Add 20 kg of triethylamine and maintain the reactor temperature at 10 °C. Add 5 kg of sec-butyllithium solution to the reactor to initiate the reaction over 30 seconds. After polymerization for 80 min, add 2.27 kg of γ-aminopropyltriethoxysilane and react for 40 min. Remove the solvent, unreacted monomers, and triethylamine to obtain polymer A3.

[0042]

[0043] The 20000L reactor has a vessel diameter of 2000mm, uses a 3-layer A320 impeller with a blade diameter of 1000mm, and has a stirring speed of 90rpm. The calculated work per unit volume of the reaction system is 0.69kW / m³. 3 The total mixing time under this stirring condition was 225 seconds.

[0044] Example 4 This embodiment provides a method for preparing conjugated diene polymers, comprising the following steps: 8500 kg of cyclohexane, 375 kg of styrene, and 1125 kg of butadiene were added to a 20000 L reactor. 20 kg of tetrahydrofuran was added, and the reactor temperature was controlled to 0 °C. 5 kg of n-butyllithium solution was added to the reactor to initiate the reaction over 30 seconds. After polymerization for 80 min, 1.31 kg of silicon tetrachloride was added, and the reaction was continued for 10 min. The solvent, unreacted monomers, and tetrahydrofuran were then removed to obtain polymer A4.

[0045]

[0046] The 20000L reactor has a vessel diameter of 2000mm, uses a 3-layer A320 impeller with a blade diameter of 1000mm, and has a stirring speed of 120rpm. The calculated work per unit volume of the reaction system is 1.62kW / m³. 3 The total mixing time under this stirring condition was 115 seconds.

[0047] Example 5 This embodiment provides a method for preparing conjugated diene polymers, comprising the following steps: 8500 kg of heptane, 375 kg of styrene, and 1125 kg of butadiene were added to a 20000 L reactor. 20 kg of tetrahydrofuran was added, and the reactor temperature was maintained at 25 °C. 7.19 kg of n-hexyllithium solution was added to the reactor to initiate the reaction over 30 seconds. After polymerization for 80 minutes, 1.31 kg of silicon tetrachloride was added, and the reaction continued for 60 minutes. The solvent, unreacted monomers, and tetrahydrofuran were then removed to obtain polymer A5.

[0048]

[0049] The 20000L reactor has a vessel diameter of 2000mm, uses a 3-layer A320 impeller with a blade diameter of 1000mm, and has a stirring speed of 120rpm. The calculated work per unit volume of the reaction system is 1.62kW / m³. 3The total mixing time under this stirring condition was 115 seconds.

[0050] Comparative Example 1: This comparative example provides a method for preparing a conjugated diene polymer, comprising the following steps: 8500 kg of cyclohexane, 375 kg of styrene, and 1125 kg of butadiene were added to a 20000 L reactor. 20 kg of tetrahydrofuran was added, and the reactor temperature was maintained at 10 °C. 5 kg of n-butyllithium solution was added to the reactor to initiate the reaction over 150 s. After polymerization for 80 min, 1.31 kg of silicon tetrachloride was added, and the reaction was continued for 10 min. The solvent, unreacted monomers, and tetrahydrofuran were then removed to obtain the conjugated diene polymer A6.

[0051]

[0052] The 20000L reactor has a vessel diameter of 2000mm, uses a 3-layer A320 impeller with a blade diameter of 1000mm, and has a stirring speed of 120rpm. The calculated work per unit volume of the reaction system is 1.62kW / m³. 3 The total mixing time under this stirring condition was 115 seconds.

[0053] Comparative Example 2: This comparative example provides a method for preparing a conjugated diene polymer, comprising the following steps: Add 8500 kg of cyclohexane, 375 kg of styrene, and 1125 kg of butadiene to a 20000 L reactor. Add 20 kg of tetrahydrofuran and maintain the reactor temperature at 10 °C. Add 5 kg of n-butyllithium solution to the reactor to initiate the reaction over 30 seconds. After polymerization for 80 minutes, add 1.31 kg of silicon tetrachloride and react for 10 minutes. Remove the solvent, unreacted monomers, and tetrahydrofuran to obtain polymer A7.

[0054]

[0055] The 20000L reactor has a vessel diameter of 2000mm, uses a 3-layer A320 impeller with a blade diameter of 1000mm, and has a stirring speed of 60rpm. The calculated work per unit volume of the reaction system is 0.2kW / m³. 3 The total mixing time under this stirring condition was 432 seconds.

[0056] Comparative Example 3: This comparative example provides a method for preparing a conjugated diene polymer, comprising the following steps: 8500 kg of cyclohexane, 375 kg of styrene, and 1125 kg of butadiene were added to a 20000 L reactor. 20 kg of tetrahydrofuran was added, and the reactor temperature was maintained at 40 °C. 5 kg of n-butyllithium solution was added to the reactor to initiate the reaction over 30 seconds. After polymerization for 80 minutes, 1.31 kg of silicon tetrachloride was added, and the reaction was continued for 10 minutes. The solvent, unreacted monomers, and tetrahydrofuran were then removed to obtain polymer A8.

[0057]

[0058] The 20000L reactor has a vessel diameter of 2000mm, uses a 3-layer A320 impeller with a blade diameter of 1000mm, and has a stirring speed of 120rpm. The calculated work per unit volume of the reaction system is 1.62kW / m³. 3 The total mixing time under this stirring condition was 115 seconds.

[0059] Test case The molecular weight, PDI, coupling rate, and radius of rotation Rg of conjugated diene polymers were determined using a gel permeation chromatography system equipped with a multi-angle laser light scattering detector, a differential refractive index detector, and an online viscometer. The instrument used was an Agilent 1260 Infinity II liquid chromatography system, equipped with a Wyatt DAWN HELEOS-II multi-angle laser light scattering detector, a Wyatt Optilab T-rEX differential refractive index detector, and a Wyatt ViscoStar-III online viscometer. The mobile phase was chromatographic grade tetrahydrofuran, the flow rate was 1.0 mL / min, the temperature was 30 °C, and the time was 45 min. The test results are shown in Table 1: Table 1

[0060] The corresponding rubber composition was prepared using the following formulation, which, by weight, is as follows: 100.0 parts conjugated diene polymer, 75.0 parts white carbon black, 5.0 parts carbon black, 12.8 parts silane Si69, 2.0 parts stearic acid, 3.0 parts zinc oxide, 37.5 parts TDAE oil, 1.5 parts sulfur, 2.0 parts TBBS, and 2.0 parts DPG; Then, the above rubber composition was mixed in a two-stage internal mixer to obtain a compound; a vulcanized rubber sample was prepared by vulcanizing it at 150°C for 30 minutes using a flat vulcanizing machine.

[0061] The above rubber composition was mixed in a two-stage internal mixer to obtain a compound; a vulcanized rubber sample was prepared by vulcanizing it at 150°C for 30 minutes using a flat vulcanizing machine.

[0062] The mechanical properties of the vulcanized rubber samples were tested using a universal testing machine; DIN abrasion was measured using a DIN abrasion tester; and dynamic mechanical properties were measured using a dynamic mechanical thermal analyzer in tensile mode. Specifically, 300% elongation at break and elongation at break were tested according to GB / T 528-2009; DIN abrasion was tested according to GB / T 9867-2008; and dynamic properties (tanδ, 0℃ and tanδ, 60℃) were tested according to GB / T 9870.1-2006.

[0063] The test results are shown in Table 2: Table 2

[0064] The conjugated diene polymer prepared by the method of this invention can significantly enhance the interaction between the polymer and the filler when used as the matrix of rubber composites, thereby comprehensively improving the overall performance of the composite material.

[0065] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A conjugated diene polymer, characterized in that, The conjugated diene polymer has the following structure: Where a, b, and c are all integers, and a / (a+b+c)=0.05-0.95, (b+c) / (a+b+c)=0.05-0.95, and n is a positive integer from 1 to 4; Wherein, R1 is selected from the chain-end groups retained after the initiator reaction; R2 is selected from the functional groups in the coupling agent that are retained after a chemical reaction. Furthermore, conjugated diene polymers satisfy the following conditions: (1) When the number of peaks in the gel chromatography-permeation chromatography molecular weight distribution curve of the conjugated diene polymer is singular or plural, the molecular weight of the lowest peak is between 1.01 and 1.

2. (2) When the number of peaks in the gel chromatography-permeation chromatography molecular weight distribution curve of the conjugated diene polymer is singular or plural, the peak molecular weight of the lowest peak is 50,000 g / mol to 2,000,000 g / mol. (3) The total mass of molecules with a molecular rotation radius Rg of less than 5 nm in the conjugated diene polymer accounts for less than 1% of the total mass of all molecules, and the molecular rotation radius Rg is determined by GPC-light scattering method.

2. The conjugated diene polymer according to claim 1, characterized in that, The initiator is selected from organolithium compounds; Preferably, the initiator structure is LiR1; R1 is selected from C1-C6 alkyl, C3-C10 cycloalkyl, C3-C10 nitrogen-containing heterocycloalkyl, C6-C12 aryl, C3-C12 heteroaryl; and C2-C10 alkylamine. Preferably, R1 is selected from at least one of ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, n-pentyl, n-hexyl, cyclohexyl, phenyl, benzyl, naphthyl, piperidinyl, hexamethyleneimine, and diethylamino.

3. The conjugated diene polymer according to claim 1 or 2, characterized in that, The coupling agent includes a silane coupling agent; Preferably, the coupling agent comprises at least one of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, and silicon tetrachloride. Preferably, R2 is selected from , , , , , , At least one of them, Indicates a connection key.

4. A method for preparing a conjugated diene polymer, characterized in that, Includes the following steps: S1: Butadiene and styrene are added to a hydrocarbon solvent under stirring conditions, and an initiator is added under stirring conditions to carry out the reaction and obtain an active polymer; S2: The active polymer obtained in S1 is reacted with a coupling agent to obtain the conjugated diene polymer; The preparation method needs to meet the following conditions: a) The total time from the start of adding the initiator to its completion is less than 2 minutes; b) During the initiator feeding and subsequent reaction process, the volumetric work per unit volume of stirring is greater than or equal to 0.5 kW / m³. 3 ; c) The initiation temperature when the initiator is added is 0-25℃; d) From the time the initiator feeding is completed, the relative deviation of the initiator concentration in any region of the system from the average initiator concentration of the system shall not exceed 5% for more than 5 minutes.

5. The preparation method according to claim 4, characterized in that, In step S1, the hydrocarbon solvent is selected from at least one of C5-C8 chain alkanes, C5-C8 cycloalkanes, and C6-C12 aromatic hydrocarbons; Preferably, the hydrocarbon solvent is selected from one or a mixture of several of cyclohexane, n-hexane, cyclopentane, pentane, heptane, and benzene; Preferably, the initiator is selected from organolithium initiators; Preferably, the initiator is selected from at least one of lithium ethyl, lithium n-propyl, lithium isopropyl, lithium n-butyl, lithium sec-butyl, lithium n-pentyl, lithium n-hexyl, lithium cyclohexyl, lithium phenyl, lithium benzyl, lithium naphthyl, lithium piperidinium, lithium hexamethyleneimine, and lithium diethylamine. Preferably, the mass ratio of the hydrocarbon solvent, butadiene, styrene, and initiator is 1500-375000:20-30000:20-30000:1; Preferably, in step S1, after adding butadiene and styrene and before adding the initiator, a reaction regulator is also added; Preferably, the reaction regulator is selected from at least one of C3-C10 ethers and C3-C10 amines; Preferably, the reaction regulator is selected from one or more of diethyl ether, dibutyl ether, tetrahydrofuran, dioxane, triethylamine, and tetramethylethylenediamine; Preferably, the mass ratio of the reaction regulator to the hydrocarbon solvent is 1:(200-600).

6. The preparation method according to claim 4 or 5, characterized in that, The reaction temperature in step S1 is 40-120℃; the reaction time is 0.1-4h.

7. The preparation method according to any one of claims 4-6, characterized in that, In step S2, the mass ratio of the active polymer prepared in S1 to the coupling agent is 300-1500:1; Preferably, the coupling agent includes at least one of silane coupling agents; Preferably, the coupling agent comprises at least one of γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, and silicon tetrachloride. Preferably, R2 is selected from: , , , , , , At least one of them, Indicates a connection key.

8. The preparation method according to any one of claims 4-7, characterized in that, The reaction temperature in step S2 is 40-120℃; the reaction time is 0.1-2h.

9. A rubber composition, characterized in that, The rubber composition comprises the conjugated diene polymer according to any one of claims 1-3 or the conjugated diene polymer prepared by the preparation method according to any one of claims 4-8; Preferably, the rubber composition further includes fillers.

10. The method for preparing the rubber composition according to claim 9, characterized in that, The process includes the following steps: mixing and vulcanizing a conjugated diene polymer with a filler to obtain the rubber composition.

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