Narrow-distribution liquid rubber based on high-steric-hindrance silane chain transfer agent and preparation method thereof

Abstract

The invention discloses narrow-distribution liquid rubber based on a high-steric-hindrance silane chain transfer agent and a preparation method of the narrow-distribution liquid rubber, and relates to the technical field of liquid rubber. Through the combination of specifically designed high-steric-hindrance adamantyldimethylsilane and the specific solvent, the technical problem that high-efficiency chain transfer and high-fidelity re-initiation are difficult to simultaneously realize in a low-cost chain transfer agent system is creatively solved, so that the production cost is remarkably reduced; and a high-performance liquid rubber product comparable with the traditional expensive n-butyllithium'pure 'living polymerization is obtained.

Description

Technical Field

[0001] This invention relates to the field of liquid rubber technology, specifically to a narrow-distribution liquid rubber based on a high-steric silane chain transfer agent and its preparation method. Background Technology

[0002] Liquid rubber is a type of rubber material with low molecular weight that flows at room temperature. It is widely used in sealants, adhesives, resin modification, coatings, and other fields. Currently, the main industrial methods for producing liquid rubber include degradation, free radical polymerization, and anionic polymerization.

[0003] Degradation method: This method degrades high molecular weight rubber through chemical or mechanical means. It has an extremely wide molecular weight distribution (PDI>0), uncontrollable functional group type and quantity, and low reactivity. It is mainly used for low-value-added products such as softeners and asphalt modifiers. Liquid rubber prepared by degradation method has a random and uncontrollable degradation process, resulting in poor product performance. The uncontrollable functional groups—the type and quantity of functional groups at the molecular chain ends are random—lead to low reactivity, difficult curing, and poor network properties, making it unsuitable for high-performance applications.

[0004] Free radical polymerization: When producing liquid rubber using traditional free radical polymerization, the controllability is poor, the molecular weight distribution is wide (PDI>2), the functional groups are introduced randomly, the functionality is low and uncontrollable, resulting in poor product performance consistency, uneven curing network, and poor mechanical properties. The mechanical properties of the final product are usually not as good as those of anionic polymerized products.

[0005] Anionic polymerization (such as the n-butyllithium system) can prepare liquid rubbers with narrow molecular weight distribution (PDI < 1.2). The ratio of monomer to initiator can be controlled, and functional groups are precisely located at both ends of the molecular chain, resulting in high functionality and the preparation of terminally functionalized "teleclaw" polymers with well-organized curing networks and excellent properties. However, the high price of the initiator n-butyllithium leads to high production costs, limiting its large-scale industrial application. Therefore, it is necessary to develop a low-cost method for preparing liquid rubber. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a narrow distribution liquid rubber based on a high steric silane chain transfer agent and its preparation method. By introducing a high steric silane chain transfer agent with a specific structure, multiple chain transfer-re-initiation cycles are realized in the anionic polymerization system, thereby solving the problem of expensive initiators, reducing the cost of producing liquid rubber by anionic polymerization, and ensuring a narrow molecular weight distribution of the product.

[0007] The technical solution of this invention is as follows: On one hand, the present invention provides a method for preparing a narrow-distribution liquid rubber based on a high-steric silane chain transfer agent, comprising the following steps: S1 Add 1200-2000 parts by weight of organic solvent and 60-100 parts by weight of butadiene to the reactor, heat to 35-45℃, and stir; S2 Add 15-35 parts by weight of n-butyllithium solution to the material obtained in step S1, and control the temperature at 60-90℃ after the reaction. Add 35-65 parts by weight of adamantyl dimethylsilane (Ad-SiMe2H) solution to S3 and stir to complete the transfer; Add 60-100 parts by weight of butadiene to S4, stir the reaction and control the temperature at 60-90℃; Add 35-65 parts by weight of adamantyl dimethylsilane solution to S5 and stir to complete the transfer. S6 Repeat steps S4 and S5 a total of 3-4 times; The reaction was terminated by adding methanol to S7, yielding liquid rubber.

[0008] The core of this invention lies in the unique chain transfer-re-initiation mechanism resulting from the use of a high-steric silane chain transfer agent: Steric hindrance effect of adamantyl alkyl groups: 1) The huge three-dimensional cage structure of adamantyl alkyl produces extremely strong steric hindrance. This steric hindrance forces the growing polymer chain (active chain, such as polybutadiene-based lithium) to mainly attack the sterically less hindrance Si-H bond, rather than the sterically more hindrance Si-C (adamantyl) bond, thereby significantly improving the selectivity and efficiency of the chain transfer reaction and ensuring that each chain transfer generates a chain-terminal Si-H functional group and a new active species (silicon-based lithium).

[0009] 2) The strong steric hindrance effect effectively shields the active center, reducing the probability of irreversible substitution and elimination side reactions between the active chain and silane, thus ensuring the controllability and "active" characteristics of the polymerization system.

[0010] Compatibility and optimization potential of solvent systems: The cyclohexane, hexane, and cyclopentane selected in this invention are all nonpolar or weakly polar solvents. In these solvents, the active centers mainly exist in the form of close ion pairs, and their high reactivity is sufficient to ensure the smooth progress of the chain transfer-re-initiation cycle. Therefore, the method of this invention can be successfully implemented in the above-mentioned solvent systems, and liquid rubber with a significantly narrower molecular weight distribution than that produced by the traditional free radical method can be prepared.

[0011] The liquid rubber prepared by this invention has the following excellent properties: 1) Narrow molecular weight distribution: Under the synergistic effect of the above-mentioned high steric hindrance silane chain transfer agent and solvent system, the chain transfer rate (ktr) and chain growth rate (kp) can reach an ideal balance. Each chain transfer can be rapidly and uniformly re-initiated, making the growth opportunities of all polymer chains in the system almost equal, thereby achieving the effect of extremely narrow molecular weight distribution (PDI≤1.2).

[0012] 2) Excellent mechanical properties: The extremely narrow molecular weight distribution and precise end-group functionalization mean that a highly regular network structure with uniform cross-linking points can be formed during subsequent cross-linking and curing. This regular network can more effectively disperse and bear stress, thereby giving the cured product higher tensile strength, resilience and lower glass transition temperature.

[0013] Preferably, the organic solvent, the solvent used in the n-butyllithium solution, and the solvent used in the adamantyl dimethylsilane solution are cyclohexane, hexane, or cyclopentane.

[0014] Preferably, in step S1, the stirring speed is 20-50 r / min; in step S2, the concentration of the n-butyllithium solution is 20 wt.%; and the reaction time is 20-40 min.

[0015] Preferably, the preparation method of adamantyl dimethylsilane is as follows: under nitrogen protection, lithium aluminum hydride suspension is added dropwise to an adamantyl dimethylchlorosilane solution at 0-5°C while stirring; after the addition is complete, the temperature is raised to room temperature and refluxed for 3.5-4.5 h; after the reaction is completed, the mixture is cooled and quenched by adding dilute sulfuric acid; then the liquid is separated, the organic phase is dried, filtered, and the solvent is removed by vacuum distillation and the product is collected to obtain adamantyl dimethylsilane.

[0016] Preferably, the solvent used for the adamantyl dimethylchlorosilane solution and the lithium aluminum hydride suspension is tetrahydrofuran, the concentration of the adamantyl dimethylchlorosilane solution is <5 mol / L, and the solid content of the lithium aluminum hydride suspension is <5 mol / L; the molar ratio of adamantyl dimethylchlorosilane to lithium aluminum hydride is 1:(0.95-1.15).

[0017] Preferably, in steps S3 and S5, the concentration of the adamantyl dimethylsilane solution is 10-20 wt.%.

[0018] Preferably, in step S3, the stirring is performed for 30-150 seconds; in step S4, the stirring reaction is performed for 20-40 minutes; and in step S5, the stirring is performed for 30-150 seconds.

[0019] Preferably, in step S7, the molar ratio of n-butyllithium to methanol is 1:1.1.

[0020] Preferably, the process further includes step S8: transferring the liquid rubber obtained in step S7 to a desolventizing vessel, performing desolventizing under negative pressure at 50-65°C for 1-1.5 hours, recovering the organic solvent, and obtaining the liquid rubber product.

[0021] On the other hand, the present invention provides a narrow distribution liquid rubber based on a high steric silane chain transfer agent, which is prepared by the above-described method for preparing a narrow distribution liquid rubber based on a high steric silane chain transfer agent.

[0022] Compared with the prior art, the present invention has the following advantages: This invention creatively solves the technical challenge of simultaneously achieving high-efficiency chain transfer and high-fidelity re-initiation in low-cost chain transfer agent systems by combining a specifically designed high-sterile-hindrance adamantyl dimethylsilane with a specific solvent. This significantly reduces production costs while yielding a high-performance liquid rubber product comparable to traditional expensive n-butyllithium "pure" living polymerization. The product prepared by this invention exhibits the following properties: number-average molecular weight of 950-1050, extremely narrow molecular weight distribution (PDI < 1.1), and good processing fluidity; its end groups are Si-H functional groups, allowing for crosslinking via hydrosilylation reactions, making it suitable for high-performance sealants, resin modification, and other fields. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0024] The preparation methods of Ad-SiMe2H used in the following examples and comparative examples are as follows: Under nitrogen protection, 1 mol of adamantyl dimethylchlorosilane and 1.5 L of anhydrous tetrahydrofuran were added to a dry three-necked flask, and the mixture was cooled to 0°C in an ice-water bath. While stirring vigorously, 1.1 L of a tetrahydrofuran suspension containing 1.1 mol of lithium aluminum hydride was added dropwise. After the addition was complete, the ice-water bath was removed, and the mixture was refluxed at room temperature for 4 h. After the reaction was complete, the mixture was cooled in an ice-water bath and quenched dropwise with dilute sulfuric acid. The mixture was separated, and the organic phase was dried over anhydrous magnesium sulfate. After filtration, the solvent was removed by vacuum distillation, and the product was further collected by vacuum distillation to obtain a colorless, transparent liquid.

[0025] The prepared Ad-SiMe2H was characterized, and the characterization results are as follows: 1H NMR spectrum 1 H NMR) (CDCl3, δ / ppm): 0.12 (s, 6H, Si-CH3), 1.65-1.95 (m, 15H, Adamantyl-H), 3.90 (s, 1H, Si-H).

[0026] Nuclear magnetic resonance silicon spectroscopy ( 29 Si NMR) (CDCl3, δ / ppm): -15.8.

[0027] The above data are in perfect agreement with the structure of the target product Ad-SiMe2H, proving that the high-purity Ad-SiMe2H product has been successfully synthesized.

[0028] The preparation method of tert-butyldimethylsilane used in the following comparative examples is as follows: Under nitrogen protection, 1 mol of tert-butyldimethylchlorosilane and 1.5 L of anhydrous tetrahydrofuran were added to a dry three-necked flask, and the mixture was cooled to 0°C in an ice-water bath. A tetrahydrofuran suspension containing 1.1 mol of lithium aluminum hydride was added dropwise with vigorous stirring. After the addition was complete, the ice-water bath was removed, and the mixture was refluxed at room temperature for 4 h. After the reaction was complete, the mixture was cooled in an ice-water bath and quenched dropwise with dilute sulfuric acid. The mixture was separated, and the organic phase was dried over anhydrous magnesium sulfate. After filtration, the solvent was removed by vacuum distillation, and the product was further collected by vacuum distillation to obtain tert-butyldimethylsilane.

[0029] The prepared tert-butyldimethylsilane was characterized, and the characterization results are as follows: 1H NMR spectrum 1 H NMR) (CDCl3, δ / ppm): 0.10 (s, 6H, Si-CH3), 0.92 (s,9H, t-Bu-H), 3.85 (s, 1H, Si-H).

[0030] Nuclear magnetic resonance silicon spectroscopy ( 29 Si NMR) (CDCl3, δ / ppm): -14.5.

[0031] The above data are in perfect agreement with the structure of the target product, tert-butyldimethylsilane, proving that a high-purity tert-butyldimethylsilane product has been successfully synthesized.

[0032] Example 1 The method for preparing narrow-distribution liquid rubber based on a high-steric silane chain transfer agent in this embodiment includes the following steps: S1 adds 1600g of cyclohexane and 80g of butadiene to a reactor equipped with a stirrer, heats to 40℃, and stirs at a speed of 45r / min; S2 Add 25g of 20wt.% n-butyllithium cyclohexane solution to the material obtained in step S1, react for 30min, and then pass cooling water through to control the temperature at 75℃. S3 was added to 50g of 15wt.% Ad-SiMe2H cyclohexane solution and stirred for 120s to complete the transfer; Add 80g butadiene to S4, stir for 30min, and after the reaction, pass cooling water through to control the temperature at 75℃. S5 is added to 50g of 15wt.% Ad-SiMe2H cyclohexane solution and stirred for 120s to complete the transfer; S6 repeats steps S4 and S5 a total of 4 times; The reaction was terminated by adding 2.75g of methanol to S7, yielding liquid rubber; S8. The liquid rubber obtained in step S7 is transferred to a desolventizing vessel and desolventized under negative pressure at -0.095 MPa and 65°C for 1 hour to recover the cyclohexane solvent and obtain a light yellow transparent viscous liquid rubber product.

[0033] Example 2 The method for preparing narrow-distribution liquid rubber based on a high-steric silane chain transfer agent in this embodiment includes the following steps: S1 adds 1200g hexane and 60g butadiene to a reactor equipped with a stirrer, heats to 35℃, and stirs at a speed of 20r / min; S2 Add 15g of 20wt.% n-butyllithium in hexane to the material obtained in step S1, react for 20min, and then pass cooling water through to control the temperature at 75℃; S3 is added to 30g of 15wt.% Ad-SiMe2H hexane solution and stirred for 30s to complete the transfer; Add 60g butadiene to S4, stir for 20min, and after the reaction, pass cooling water through to control the temperature at 60℃. S5 is added to 35g of 15wt.% Ad-SiMe2H hexane solution and stirred for 30s to complete the transfer; S6 repeats steps S4 and S5 a total of 4 times; The reaction was terminated by adding 1.65g of methanol to S7, yielding liquid rubber; S8. The liquid rubber obtained in step S7 is transferred to a desolventizing vessel and desolventized under negative pressure at -0.095 MPa and 50°C for 1 hour to recover the cyclohexane solvent and obtain a light yellow transparent viscous liquid rubber product.

[0034] Example 3 The method for preparing narrow-distribution liquid rubber based on a high-steric silane chain transfer agent in this embodiment includes the following steps: S1 adds 2000g of cyclopentane and 100g of butadiene to a reactor equipped with a stirrer, heats to 45℃, and stirs at a speed of 50r / min; S2 Add 35g of 20wt.% n-butyllithium cyclopentane solution to the material obtained in step S1, react for 40min, and then pass cooling water through to control the temperature at 90℃. S3 was added to 65g of 15wt.% Ad-SiMe2H cyclopentane solution and stirred for 150s to complete the transfer; Add 100g butadiene to S4, stir for 40min, and after the reaction, pass cooling water through to control the temperature at 90℃. S5 is added to 65g of 15wt.% Ad-SiMe2H cyclopentane solution and stirred for 150s to complete the transfer; S6 repeats steps S4 and S5 a total of 3 times; The reaction was terminated by adding 3.85g of methanol to S7, yielding liquid rubber; S8. The liquid rubber obtained in step S7 is transferred to a desolventizing vessel and desolventized under negative pressure at -0.095 MPa and 60°C for 1.5 h to recover the cyclohexane solvent and obtain a light yellow transparent viscous liquid rubber product.

[0035] Comparative Example 1 The difference from Example 1 is that Ad-SiMe2H in Example 1 is replaced with tert-butyldimethylsilane.

[0036] Comparative Example 2 The difference from Example 2 is that Ad-SiMe2H in Example 2 is replaced with tert-butyldimethylsilane.

[0037] Comparative Example 3 The difference from Example 3 is that Ad-SiMe2H in Example 3 is replaced with tert-butyldimethylsilane.

[0038] Comparative Example 4 The preparation method of the liquid rubber in Comparative Example 4 includes the following steps: S1 adds 1600g toluene and 80g butadiene to a reactor equipped with a stirrer, heats to 40℃, and stirs at a speed of 45r / min; S2 Add 25g of a 20wt.% toluene solution of n-butyllithium to the material obtained in step S1, react for 30min, and then pass cooling water through to control the temperature at 75℃; S3 is added to 50g of 15wt.% Ad-SiMe2H toluene solution and stirred for 120s to complete the transfer; Add 80g butadiene to S4, stir for 30min, and after the reaction, pass cooling water through to control the temperature at 75℃. S5 is added to 50g of 15wt.% Ad-SiMe2H toluene solution and stirred for 120s to complete the transfer; S6 repeats steps S4 and S5 a total of 4 times; The reaction was terminated by adding 11g of methanol to S7, yielding liquid rubber. S8. The liquid rubber obtained in step S7 is transferred to a desolventizing vessel and desolventized under negative pressure at -0.095 MPa and 65°C for 1 hour to recover toluene solvent and obtain the liquid rubber product.

[0039] Comparative Example 5 The preparation method of the liquid rubber in Comparative Example 5 includes the following steps: S1 adds 1600g of cyclohexane and 80g of butadiene to a reactor equipped with a stirrer, heats to 40℃, and stirs at a speed of 45r / min; S2 Add 100g of 20wt.% n-butyllithium cyclohexane solution to the material obtained in step S1, react for 50min, and then pass cooling water through to control the temperature at 75℃. The reaction was terminated by adding 44g of methanol to S3, yielding liquid rubber; S4. The liquid rubber obtained in step S3 is transferred to a desolventizing vessel and desolventized under negative pressure at -0.095 MPa and 65°C for 1 hour to recover the cyclohexane solvent and obtain a light yellow transparent viscous liquid rubber product.

[0040] The liquid rubber products prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to performance tests, and the test methods are as follows: Number average molecular weight M n Molecular weight distribution index (PDI) was tested according to ISO 11344:2016; viscosity was tested according to GB / T 41940-2022; glass transition temperature (Tg) was also tested. g Tests were conducted according to GB / T 9870.3-2025; appearance was observed according to GB / T 18950-2023. Test results are shown in Table 1. Table 1 Performance test results of the liquid rubber products prepared in Examples 1-3 and Comparative Examples 1-5

[0041] The number-average molecular weight, molecular weight distribution index, viscosity, appearance, and glass transition temperature of the liquid rubber products prepared in Examples 1-3 and Comparative Examples 1-5 in Table 1 show that the molecular weight of the liquid rubber prepared by the present invention is controllable and the molecular weight distribution is narrower.

[0042] As shown in Table 1, the molecular weight distribution index (PDI) of the liquid rubber products prepared in Examples 1-3 using the highly sterically hindered Ad-SiMe2H as a chain transfer agent is 1.03-1.08, significantly lower than that of Comparative Examples 1-3 using tert-butyldimethylsilane (PDI = 1.15-1.28). This indicates that the polymerization reaction in Examples 1-3 was well controlled, with uniform chain growth, effectively controlling the chain transfer process and reducing the heterogeneity of chain termination and chain transfer. This fully demonstrates the decisive role of the large steric hindrance of the adamantyl alkyl group of Ad-SiMe2H in achieving efficient and controllable chain transfer-re-initiation cycles.

[0043] Compared to Example 1, the liquid rubber product prepared in Comparative Example 4 has an extremely wide molecular weight distribution (PDI = 2.14, much higher than 1.03 in Example 1) and a glass transition temperature (T0). g =-90℃) slightly higher than Example 1 (T g =-95℃). This is because Comparative Example 4 uses toluene as a solvent. Toluene is a polar solvent, which changes the form of the active center (polybutadiene lithium), disrupts the uniformity of the chain transfer-re-initiation cycle, leads to uneven chain transfer reaction, increases side reactions, and ultimately significantly broadens the molecular weight distribution; at the same time, the polar environment affects the regularity of the polymer chain, resulting in T g Slightly higher, resulting in a decrease in mechanical performance potential.

[0044] Compared to Example 1, Comparative Example 5 did not add a chain transfer agent and relied on a large amount of n-butyllithium to directly initiate polymerization, although PDI (1.03) and M n (1045 g / mol) is similar to Example 1, but the amount of n-butyllithium and methanol as the terminator is 4 times that of Example 1. The high price of n-butyllithium leads to a significant increase in production costs; and it cannot achieve end-group functionalization through chain transfer (lacking Si-H end groups), which limits its application in high-performance sealants, resin modification and other fields.

[0045] In summary, this invention creatively solves the technical challenge of simultaneously achieving high-efficiency chain transfer and high-fidelity re-initiation in low-cost chain transfer agent systems by combining a specially designed high-sterile-hindrance adamantyl dimethylsilane with a specific solvent. This results in a high-performance liquid rubber product comparable to the traditional expensive n-butyllithium "pure" living polymerization while significantly reducing production costs.

Claims

1. Process for the preparation of a narrow distribution liquid rubber based on a high steric hindrance silane chain transfer agent, characterized in that, Comprising the following steps: S1 adding 1200-2000 parts by weight of organic solvent, 60-100 parts by weight of butadiene into a reaction kettle, heating to 35-45℃, stirring; S2 adding 15-35 parts by weight of n-butyllithium solution to the material obtained in step S1, controlling the temperature at 60-90℃ after reaction; S3 adding 35-65 parts by weight of adamantyl dimethyl silane solution, stirring to complete the transfer; S4 adding 60-100 parts by weight of butadiene, stirring and reacting, and controlling the temperature at 60-90℃; S5 adding 35-65 parts by weight of adamantyl dimethyl silane solution, stirring to complete the transfer; S6 repeating steps S4 and S5 for 3-4 times; S7 adding methanol to terminate the reaction to obtain liquid rubber.

2. The process for the preparation of a high-hindered silane chain transfer agent based narrow distribution liquid rubber according to claim 1, characterized in that, The solvents used for the organic solvent, n-butyllithium solution and adamantyl dimethyl silane solution are cyclohexane, hexane or cyclopentane.

3. The process for preparing a high-hindered silane chain transfer agent based narrow distribution liquid rubber according to claim 1, characterized in that, In step S1, the stirring speed is 20-50 r / min; in step S2, the concentration of n-butyllithium solution is 20 wt.%; and the reaction time is 20-40 min.

4. The process for preparing a high-hindered silane chain transfer agent based narrow distribution liquid rubber according to claim 1, characterized in that, The preparation method of adamantyl dimethyl silane is as follows: under nitrogen protection, lithium aluminum hydride suspension is added dropwise to adamantyl dimethyl chlorosilane solution at 0-5℃, and stirring is performed during dropwise addition; after dropwise addition is completed, the temperature is raised to room temperature and refluxed for 3.5-4.5 h; after the reaction is completed, cooling is performed and dilute sulfuric acid is added dropwise for quenching; then, liquid separation is performed, the organic phase is dried, filtered, and the solvent is removed by distillation under reduced pressure to collect the product, i.e. adamantyl dimethyl silane.

5. The process for the preparation of a high-hindered silane chain transfer agent based narrow distribution liquid rubber according to claim 4, characterized in that, The solvents used for adamantyl dimethyl chlorosilane solution and lithium aluminum hydride suspension are tetrahydrofuran, the concentration of adamantyl dimethyl chlorosilane solution is <5 mol / L, and the solid content of lithium aluminum hydride suspension is <5 mol / L; the molar ratio of adamantyl dimethyl chlorosilane to lithium aluminum hydride is 1: (0.95-1.15).

6. The process for preparing a high-hindered silane chain transfer agent based narrow distribution liquid rubber according to claim 1, characterized in that, In steps S3 and S5, the concentration of adamantyl dimethyl silane solution is 10-20 wt.%.

7. The process for preparing a high-hindered silane chain transfer agent based narrow distribution liquid rubber according to claim 1, characterized in that, In step S3, stirring is performed for 30-150 s; in step S4, stirring and reaction are performed for 20-40 min; and in step S5, stirring is performed for 30-150 s.

8. The process for preparing a high-hindered silane chain transfer agent based narrow distribution liquid rubber according to claim 1, characterized in that, In step S7, the molar ratio of n-butyllithium to methanol is 1:1.

1.

9. The process for preparing a high-hindered silane chain transfer agent based narrow distribution liquid rubber according to claim 1, characterized in that, It further comprises step S8: transferring the liquid rubber obtained in step S7 to a desolventizing kettle, and performing negative pressure desolventizing at 50-65℃ under negative pressure for 1-1.5 h to recover the organic solvent and obtain a liquid rubber product.

10. A narrow distribution liquid rubber based on a high steric hindrance silane chain transfer agent, characterized in that, Prepared by the preparation method of a high steric hindrance silane chain transfer agent-based narrow distribution liquid rubber according to any one of claims 1-9. Prepared by the preparation method of a high steric hindrance silane chain transfer agent-based narrow distribution liquid rubber according to any one of claims 1-9.

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