A star-shaped functionalized solution-polymerized styrene-butadiene rubber and its preparation method

Abstract

This invention provides a star-shaped functionalized solution-polymerized styrene-butadiene rubber and its preparation method. The preparation method includes the following steps: S10, under an inert atmosphere, in an organic solvent, using a conjugated diene monomer as the polymerization monomer and a substance obtained by premixing alkyl lithium with a front-end modifier as the functionalization initiator, solution polymerization is carried out to obtain a polymer precursor; S20, an active coupling agent is added to the polymer precursor to obtain a star-shaped polymer with an active core and polar functional groups at the ends of each star arm; S30, a functionalizing agent is added to the star-shaped polymer to obtain a star-shaped functionalized solution-polymerized styrene-butadiene rubber with both end-chain and mid-chain functionalization. This invention, by introducing a front-end modifier and an active coupling agent, allows the star core to retain its active center, and introduces a functionalizing agent for mid-chain modification, enhancing the interfacial bonding force between silica and styrene-butadiene rubber, thereby reducing the hysteresis loss of tire rubber and imparting it with wear resistance, fatigue resistance, and wet skid-rolling resistance balance.

Description

Technical Field

[0001] This invention relates to the field of rubber technology, and more specifically, to a star-shaped functionalized solution-polymerized styrene-butadiene rubber and its preparation method. Background Technology

[0002] Solution-polymerized styrene-butadiene rubber (SSBR) is a random copolymer of styrene and butadiene. Due to its advantages such as high monomer conversion rate, low polymerization auxiliaries, and low waste emissions, it has become a key research focus in the field of green tires. Its narrow molecular weight distribution and controllable microstructure allow for the synthesis of rubber types with different properties to meet various application requirements, such as high-styrene SSBR, high, medium, and low vinyl SSBR, and terminally functionalized SSBR, resulting in a rich variety of rubber types. The automotive industry's demand for energy-saving tires is gradually increasing. Studies show that energy loss due to overcoming tire rolling resistance during vehicle operation accounts for approximately 30% of total energy consumption. To address this issue, the "SSBR + silica" system has become the standard configuration for low rolling resistance tread compounds. Strengthening SSBR with silica to solve the "magic triangle" problem (i.e., the contradiction between rolling resistance, wet grip performance, and abrasion resistance) has become an industry consensus.

[0003] However, the presence of numerous silanol groups on the surface of silica leads to poor dispersibility in styrene-butadiene rubber (SBR). Therefore, how to regulate the interfacial bonding between silica and SBR to achieve uniform dispersion of silica in the rubber matrix remains a critical issue that urgently needs to be addressed. Currently, common solutions include adding silane coupling agents (such as bis(triethoxysilane)tetrasulfide and γ-mercaptopropyltrimethoxysilane) during rubber compounding, or surface modification of silica to improve its interfacial bonding with SBR. However, the use of silane coupling agents not only requires large amounts but also leads to "migration" of the silane coupling agent in the final vulcanized product, resulting in a decline in rubber properties. Furthermore, the effect of silane coupling agents on improving the interfacial bonding between silica and SBR is limited, and the surface modification process is complex and ineffective.

[0004] To improve the processing and dynamic properties of styrene-butadiene rubber (SBR), researchers have also employed techniques such as branching coupling and end-capping modification. For example, an amino-functionalized initiator was prepared by reacting cycloheximine with n-butyllithium, which then initiated the random copolymerization of butadiene and styrene to prepare amino-functionalized solution-polymerized SBR. Alkyllithium initiators were used to initiate the copolymerization of butadiene and styrene, and various end-capping agents (such as triethoxysilyl compounds and tetraglycidyl compounds) were used to modify the SBR, ultimately introducing amino and / or siloxane groups at the rubber ends to improve its properties.

[0005] Although these technologies can introduce polar functional groups such as amino and siloxane groups into the molecular chain ends of styrene-butadiene rubber (SBR), the improvement effect of chain-end modification on the interfacial bonding between fillers and polymers is very limited due to the limited number of chain-end groups. Such methods typically face a series of problems: first, chain-end modifiers are structurally complex, expensive, and highly toxic; second, the modifiers have low reactivity, require large addition amounts, and generate numerous side reactions; finally, the selection range of polar functional groups is narrow, typically limited to tertiary amine and siloxane groups. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes a star-shaped functionalized solution-polymerized styrene-butadiene rubber (SBR) and its preparation method. By combining star-shaped branched structure design with chain-end functionalization technology, it aims to significantly reduce the rolling resistance of tire tread rubber and improve processing performance, while also maintaining the mechanical properties of the rubber. Furthermore, through "active coupling technology" and "in-chain functionalization technology," the number of polar functional groups in the solution-polymerized SBR is further increased, greatly improving the dispersibility of silica and thus enhancing the overall performance of downstream tire products. This approach effectively solves the problems of poor filler dispersibility and limited performance improvement in existing technologies, providing an effective solution for the development of green and energy-saving tires.

[0007] To achieve the above objectives, the present invention provides a method for preparing star-shaped functionalized solution-polymerized styrene-butadiene rubber (SBR). The preparation method includes the following steps: S10, under an inert atmosphere, in an organic solvent, using a conjugated diene monomer as the polymerization monomer and a substance obtained by premixing alkyl lithium with a front-end modifier as the functionalization initiator, solution polymerization is carried out to obtain a polymer precursor; S20, an active coupling agent is added to the polymer precursor, and the reaction is carried out to obtain a star-shaped polymer with an active core and polar functional groups at the ends of each star arm; S30, a functionalizing agent is added to the star-shaped polymer, and the reaction is carried out to obtain a star-shaped functionalized solution-polymerized SBR with both end-chain and mid-chain functionalization; wherein, the functionalizing agent includes at least one of p-dimethylaminobenzophenone, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; the active coupling agent is a difunctional conjugated diene compound.

[0008] Furthermore, the conjugated diene monomer includes at least one of butadiene, isoprene, styrene, isoprene, 2,4-dimethyl-1,3-butadiene, and α-methylstyrene; and / or alkyl lithium includes at least one of methyl lithium, ethyl lithium, isopropyl lithium, n-butyl lithium, tert-butyl lithium, and sec-butyl lithium.

[0009] Furthermore, the front-end modifier includes at least one of N,N-dimethylamine, diphenylamine, cyclohexylimine, and pyrrolidine; and / or the active coupling agent includes at least one of divinylbenzene and 1,4-diisopropenylbenzene.

[0010] Further, S10 specifically includes: S11, under a closed inert atmosphere, mixing organic solvent and conjugated diene monomer at a mass ratio of (80-95):(5-20) to obtain a monomer solution; S12, under a temperature condition of -78℃ to 30℃, first premixing the dissociative agent and the pre-modifier at a molar ratio of (1.0-1.5):1 for 2min-10min, then premixing the pre-modifier and alkyl lithium at a molar ratio of 1:(1.0-1.3) for 2min-200min to obtain a functionalized initiator; S13, adding the functionalized initiator to the monomer solution at a temperature condition of 0℃-60℃ to initiate polymerization, with a reaction time of 10min-200min, to obtain a polymer precursor.

[0011] Furthermore, after S11, the method further includes: adding a cyclohexane solution of alkyllithium to the monomer solution at a temperature of 0℃-20℃; wherein the mass ratio of alkyllithium to cyclohexane is (10-20):(80-90).

[0012] Further, S20 specifically includes: adding a cyclohexane solution of the active coupling agent to the polymer precursor, and stirring and mixing at a temperature of 0℃-60℃ for a reaction time of 5min-120min to obtain a star-shaped polymer with an active core and polar functional groups at the end of each arm; wherein the mass ratio of the active coupling agent to cyclohexane is (1-3):(97-99).

[0013] Furthermore, the molar ratio of the functionalizing initiator, the active coupling agent, and the functionalizing reagent is 1:(2.0-6.0):(0.8-1.6).

[0014] Furthermore, the preparation method also includes: S40, adding an antioxidant to the star-shaped functionalized solution-polymerized styrene-butadiene rubber, concentrating it, and then vacuum drying it to obtain the finished rubber.

[0015] This invention provides a star-shaped functionalized solution-polymerized styrene-butadiene rubber, which is prepared by the preparation method described above.

[0016] Furthermore, the star-shaped functionalized solution-polymerized styrene-butadiene rubber uses butadiene and styrene as polymerizing monomers. The mass fraction of styrene monomer in the star-shaped functionalized solution-polymerized styrene-butadiene rubber is 5%-95%, and the mass fraction of vinyl structural units in the butadiene structural units is 6%-90%. The Mooney viscosity of the star-shaped functionalized solution-polymerized styrene-butadiene rubber is 30-80, the glass transition temperature is -50℃ to 0℃, and the modification rate of polar functional groups of the polymer is >90%. The nitrogen content of the star-shaped functionalized solution-polymerized styrene-butadiene rubber is 2000-3500 mg / kg of solution-polymerized styrene-butadiene rubber.

[0017] By adopting the technical solution of the present invention, the following technical effects can be achieved:

[0018] (1) The present invention adopts an innovative combination of "functionalized initiator preparation technology" + "DVB active coupling technology" + "functionalization technology in star core chain". By introducing polar functional groups into the end group and "star core" of each "star arm" of star-shaped functionalized solution polymerized styrene-butadiene rubber, the interfacial bonding force between silica and styrene-butadiene rubber can be significantly enhanced, thereby reducing the hysteresis loss of the final tire rubber product and giving it high wear resistance, fatigue resistance and excellent wet skid-rolling resistance balance.

[0019] (2) This invention utilizes the active groups of functionalized reagents or their rigid cyclic backbone and bifunctional characteristics to undergo coupling reactions with the active lithium sites at the ends of solution-polymerized styrene-butadiene rubber chains. These reagents act as a "core" connecting multiple polymer chains, forming a unique cyclic multi-star-arm structure. This unique star-shaped structure enhances the inter-chain interactions through multi-arm crosslinking and reduces interfacial defects through the interaction between functional groups and fillers (such as silica), thereby exhibiting higher tensile strength and better wear resistance;

[0020] (3) The star-shaped functionalized solution polystyrene-butadiene rubber of the present invention has a star-shaped branched structure, which can significantly improve the processing performance and dynamic performance while taking into account the physical and mechanical properties of the rubber.

[0021] (4) In this invention, the front-end modifier, back-end functionalizing agent, conjugated diene monomer, alkyl lithium initiator and DVB coupling agent used to prepare star-functionalized solution polystyrene-butadiene rubber are all commonly used industrial chemicals with the advantages of being inexpensive, readily available and non-toxic.

[0022] (5) The preparation principle of the functionalized initiator and star-shaped functionalized polymer in this invention is simple, the operation is convenient, the reaction conditions are mild, there are no side reactions, and the product conversion rate is high.

[0023] (6) The chemical structures of the front-end modifier and the back-end functionalizing agent used in this invention are diverse, and the types of functional groups available are varied, which can realize the customized design of polar groups and material properties of star-functionalized SSBR. Attached Figure Description

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 A reaction principle diagram of star-shaped functionalized solution polymerized styrene-butadiene rubber provided in an embodiment of the present invention;

[0026] Figure 2 This invention provides an embodiment of the in-chain functionalization mechanism of star-shaped functionalized solution-polymerized styrene-butadiene rubber. Detailed Implementation

[0027] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Solution-polymerized styrene-butadiene rubber (SSBR) is a random copolymer of styrene and butadiene, possessing advantages such as high monomer conversion rate, low polymerization auxiliaries, and low waste emissions. The synthesized rubber exhibits a narrow molecular weight distribution and controllable microstructure, allowing for the synthesis of various types of rubber, including high-styrene SSBR, high-, medium-, and low-vinyl SSBR, and terminally functionalized SSBR, to meet diverse application requirements. Due to its rich variety of rubber types, solution-polymerized SSBR has become an important research direction for green tires both domestically and internationally.

[0029] The automotive industry is increasingly demanding energy-efficient tires. Studies show that energy consumption from overcoming tire rolling resistance accounts for 30% of total energy consumption during vehicle operation. To reduce tire energy loss, the "SSBR + silica" system has become the standard for low rolling resistance tread compounds. Using silica to reinforce SSBR to prepare tread compounds to solve the "magic triangle" problem has become an industry consensus. However, due to the large number of silanol groups on the surface of silica, its dispersibility in styrene-butadiene rubber (SBR) is poor. How to control the interfacial bonding force between silica and SBR to ensure uniform dispersion of polar silica in the rubber matrix remains a key challenge that urgently needs to be overcome.

[0030] During rubber compounding, silane coupling agents (such as bis(triethoxysilane)tetrasulfide, γ-mercaptopropyltrimethoxysilane, etc.) can be added, or these silane coupling agents can be used to modify the surface of silica, thereby adjusting the interfacial properties of silica and achieving good interfacial bonding between silica and styrene-butadiene rubber (SBR). However, adding silane coupling agents during compounding not only requires large quantities, but also leads to the problem of silane coupling agent "migration" in vulcanized products, resulting in a decline in rubber properties. Furthermore, this method does not significantly improve the interfacial bonding between silica and SBR. On the other hand, the pretreatment process of surface modification of silica using silane coupling agents is relatively complex, with poor modification effects and limited improvement in interfacial bonding.

[0031] In addition, branching coupling and end-capping modification are also common methods to improve the processing and dynamic properties of styrene-butadiene rubber (SBR). LG Chem Corporation of South Korea described two methods in its patent CN107810209B: First, cycloheximine reacts with n-butyllithium and immediately reacts with a conjugated diene (such as butadiene) to prepare an amino-functionalized initiator, which is used to initiate the random copolymerization of butadiene and styrene, thereby preparing chain-terminated amino-functionalized solution-polymerized SBR; second, an amino-functionalized anionic initiator is prepared by reacting a vinyl-N,N-dimethylbenzylamine compound with butyllithium, which can also be used to prepare chain-terminated amino-functionalized solution-polymerized SBR.

[0032] Asahi Kasei Corporation of Japan, in its patent CN105175582B, describes a method for initiating the random copolymerization of butadiene and styrene using an alkyllithium initiator, followed by the addition of end-capping agents such as 1-[3-(triethoxysilyl)propyl]-4-methylpiperazine, 1-[3-(triethoxysilyl)propyl]-4-(trimethylsilyl)piperazine, tetraglycidyl-1,3-diaminomethylcyclohexane, 2-[3-(trimethoxysilyl)propyl]-1,3-dimethylimidazolidine, [3-(dimethylamino)propyl]trimethoxysilane, and 1,3-dimethyl-2-imidazolinone. These end-capping agents can introduce amino and / or siloxane groups at the ends of styrene-butadiene rubber, and the end-capping modification rate can reach over 80%.

[0033] CN105777946B discloses a double-ended modified star-shaped solution-polymerized styrene-butadiene rubber, its preparation method, and the vulcanized rubber and its applications. The invention utilizes an organolithium initiator for initiation, coupling with coupling agents such as DVB, and silane end-capping to form a double-ended modified star-shaped solution-polymerized styrene-butadiene rubber. In this invention, the initiator only introduces silane chains, while silane and other functional groups are introduced through end-capping.

[0034] In addition, CN102482359A also uses piperazine compounds containing siloxane substituents as end-capping agents for styrene-butadiene rubber; CN107250172B and CN109476778B use silazane compounds as end-capping agents for styrene-butadiene rubber; CN107835752A uses 3-isocyanate-propyltrimethoxysilane to react with hydroxyl-terminated polybutadiene to prepare silane-modified polybutadiene rubber for tire components.

[0035] The above methods can introduce polar functional groups such as amino and siloxane groups into the molecular chain ends of solution-polymerized styrene-butadiene rubber (SBR), achieving a chain end modification rate of over 80%. However, these methods can only introduce polar functional groups into the molecular chain ends. Since the number of macromolecular chain ends of solution-polymerized SBR is very limited, the chain end modification technology has a very limited effect on improving the interfacial bonding force between the filler and the polymer. In addition, the above-mentioned end-capping agents have the following problems: (1) complex structure and difficult to obtain; (2) high price; (3) very obvious odor and strong toxicity; (4) low reactivity, large addition amount, and many side reactions; (5) small range of polar functional groups, generally tertiary amine groups and siloxane groups are the main ones.

[0036] In addition, most common or functionalized grades of solution-polymerized styrene-butadiene rubber (SBR) have linear molecular chains, large molecular weights, and are difficult to mix and process, requiring oil extrusion before use. However, oil-extended rubber will have reduced performance. Therefore, some SBRs adopt a star-branched structural design to improve processing performance while maintaining the excellent properties of the rubber. It can also reduce the rolling resistance of downstream tire tread rubber by reducing the number of free ends.

[0037] Therefore, we are considering developing a star-shaped polymer functionalization modification technology for solution-polymerized styrene-butadiene rubber (SBR). On the one hand, we will combine the star-shaped branched structure design with chain-end functionalization technology to significantly reduce the rolling resistance of downstream tire tread rubber, improve processing performance, and maintain excellent mechanical properties. On the other hand, we will combine "active coupling technology" and "in-chain functionalization technology" to further increase the number of polar functional groups in solution-polymerized SBR, greatly improve the dispersion of silica, and fully improve the overall performance of downstream tire products.

[0038] The present invention provides a method for preparing star-shaped functionalized solution-polymerized styrene-butadiene rubber (SBR). The preparation method includes the following steps: S10, under an inert atmosphere, in an organic solvent, using a conjugated diene monomer as the polymerization monomer and a substance obtained by premixing alkyl lithium with a front-end modifier as the functionalization initiator, solution polymerization is carried out to obtain a polymer precursor; S20, an active coupling agent is added to the polymer precursor, and the reaction is carried out to obtain a star-shaped polymer with an active core and polar functional groups at the end of each star arm; S30, a functionalizing agent is added to the star-shaped polymer, and the reaction is carried out to obtain a star-shaped functionalized solution-polymerized SBR with both end-chain and mid-chain functionalization; wherein, the functionalizing agent includes at least one of p-dimethylaminobenzophenone, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; the active coupling agent is a difunctional conjugated diene compound.

[0039] This invention introduces a pre-modifier before the reaction and uses an active coupling agent to connect the polymerizable SSBR active chains. After coupling, the active center is retained at the very center of the star-shaped molecular chain (i.e., the star core). Finally, a functionalizing agent is introduced for in-chain modification. This invention innovatively combines "functionalized initiator preparation technology," "DVB active coupling technology," and "star core in-chain functionalization technology." By introducing polar functional groups at the end groups of each "star arm" and the "star core" of the star-shaped functionalized solution-polymerized styrene-butadiene rubber, the interfacial bonding force between silica and styrene-butadiene rubber can be significantly enhanced, thereby reducing the hysteresis loss of the final tire rubber product and endowing it with high wear resistance, fatigue resistance, and excellent wet skid-rolling resistance balance.

[0040] When a bifunctional conjugated diene compound, such as DVB (active coupling agent), is added to a polymer precursor solution, the active coupling agent undergoes an active coupling reaction with the active chain ends of the polymer precursor. The resulting star polymer still has a carbanion active center in its core, which can react with functionalizing reagents, and each star arm end has a polar functional group.

[0041] Existing technologies typically use siloxane-based end-capping agents, which can experience molecular weight jumps or even cross-linking during production and storage, negatively impacting product processing and performance. The functionalizing agents used in this invention include at least one of p-dimethylaminobenzophenone, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. After these functionalizing agents react with the active centers at the molecular chain star core, no side reactions such as molecular weight increase or cross-linking occur during subsequent production and storage.

[0042] The preparation process of the star polymer was carried out under a nitrogen atmosphere with a purity of 99.999% or higher. The star polymer was prepared by using a functionalized initiator to initiate polymerization of conjugated diene monomers in cyclohexane solvent by premixing alkyl lithium with a front-end modifier. Finally, it was obtained by coupling with divinyl aromatic hydrocarbons and reacting with an equimolar amount of functionalized reagents in the chain.

[0043] In some embodiments of this application, the conjugated diene monomer includes at least one of butadiene, isoprene, styrene, isoprene, 2,4-dimethyl-1,3-butadiene, and α-methylstyrene; and / or alkyllithium includes at least one of methyllithium, ethyllithium, isopropyllithium, n-butyllithium, tert-butyllithium, and sec-butyllithium.

[0044] Olefin monomers with conjugated structures can react with other monomers in polymerization reactions to form polymers with specific properties, which have important applications in the synthesis of rubber. Different conjugated diene monomers have different structures and reactivity; selecting different monomers can control the properties and performance of the polymer. In this invention, alkyllithium typically acts as an initiator to drive the polymerization reaction of the conjugated diene monomers. Different types of alkyllithium (such as methyllithium, ethyllithium, etc.) exhibit different activities and selectivities in the reaction, thus affecting the properties of the final polymer.

[0045] In some embodiments of this application, the front-end modifier includes at least one of N,N-dimethylamine, diphenylamine, cyclohexylimine, and pyrrolidine; and / or the active coupling agent includes at least one of divinylbenzene and 1,4-diisopropenylbenzene; and / or the functionalizing agent includes at least one of p-dimethylaminobenzophenone, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

[0046] The role of front-end modifiers is to chemically modify the ends of polymer chains, providing the active groups required for subsequent functionalization reactions. N,N-dimethylamine, diphenylamine, cycloheximine, and pyrrolidine, as front-end modifiers, can help introduce nitrogen- or aromatic ring groups, which can effectively affect the final properties of the polymer, such as enhancing polarity, improving solubility, or improving compatibility with other materials.

[0047] Active coupling agents are used to promote cross-linking reactions between polymer molecular chains or to promote the bonding of polymers with other materials. Compounds such as divinylbenzene and 1,4-diisopropenylbenzene have double bonds or multiple olefin structures and can initiate cross-linking or coupling reactions under appropriate conditions, thereby achieving the connection between different polymer chains or the interaction of multiple polymers, improving the overall performance and structural strength of the material. Preferably, divinylbenzene includes ortho / m / p-divinylbenzene and ortho / m / p-diisopropenylbenzene.

[0048] Functionalizing agents are mainly used to further modify the middle part of the polymer chain, endowing it with specific functional groups. Specifically, the listed functionalizing agents, such as p-dimethylaminobenzophenone, diphenylmethane diisocyanate, and toluene diisocyanate, have active groups such as isocyanate and amino groups, which can be used for further reaction modification to give the polymer more functionality and improve its performance in specific applications.

[0049] In some embodiments of this application, S10 specifically includes: S11, mixing an organic solvent and a conjugated diene monomer at a mass ratio of (80-95):(5-20) under a closed inert atmosphere to obtain a monomer solution; S12, premixing a dissociative agent and a pre-modifier at a molar ratio of (1.0-1.5):1 for 2 min-10 min under a temperature condition of -78°C to 30°C, and then premixing a pre-modifier and an alkyl lithium at a molar ratio of 1:(1.0-1.3) for 2 min-200 min to obtain a functionalized initiator; S13, adding the functionalized initiator to the monomer solution at a temperature condition of 0°C-60°C to initiate polymerization for a reaction time of 10 min-200 min to obtain a polymer precursor.

[0050] Preferably, the dissociative agent can be tetrahydrofuran.

[0051] In some embodiments of this application, after S11, the method further includes: adding a cyclohexane solution of alkyl lithium to the monomer solution at a temperature of 0°C-20°C; wherein the mass ratio of alkyl lithium to cyclohexane is (10-20):(80-90).

[0052] Adding alkyllithium solution at low temperatures can reduce the impact of impurities while maintaining the stability of the desired reaction. In polymerization reactions, impurities (such as moisture, oxygen in the air, residual reactants or byproducts, etc.) can interfere with the reaction or affect the quality of the final product. The purpose of adding alkyllithium solution is to remove or transform these impurities by reacting with them, thereby ensuring the purity of the reaction system and the smooth progress of the reaction.

[0053] In some embodiments of this application, S20 specifically includes: adding a cyclohexane solution of an active coupling agent to a polymer precursor and stirring and mixing at a temperature of 0°C-60°C for a reaction time of 5 min-120 min to obtain a star-shaped polymer with an active core and polar functional groups at the end of each arm; wherein the mass ratio of the active coupling agent to cyclohexane is (1-3):(97-99).

[0054] In this step, the active coupling agent is used to further modify the molecular structure of the polymer precursor, giving it a star-shaped structure and introducing polar functional groups at the ends. Dissolving the coupling agent in cyclohexane improves its solubility in solution and promotes reaction homogeneity. An appropriate concentration of the active coupling agent can effectively promote the polymerization reaction while avoiding excessive use that could trigger unnecessary side reactions.

[0055] In some embodiments of this application, the molar ratio of the functionalizing initiator, the active coupling agent, and the functionalizing reagent is 1:(2.0-6.0):(0.8-1.6).

[0056] In some embodiments of this application, the preparation method further includes: S40, adding an antioxidant to star-shaped functionalized solution-polymerized styrene-butadiene rubber, concentrating it, and then vacuum drying it to obtain the finished rubber.

[0057] The embodiments of the present invention provide a star-shaped functionalized solution-polymerized styrene-butadiene rubber, which is prepared by the preparation method described above.

[0058] In some embodiments of this application, the star-shaped functionalized solution-polymerized styrene-butadiene rubber uses butadiene and styrene as polymerizing monomers. The mass fraction of styrene monomer in the star-shaped functionalized solution-polymerized styrene-butadiene rubber is 5%-95%, and the mass fraction of vinyl structural units in the butadiene structural units is 6%-90%. The Mooney viscosity of the star-shaped functionalized solution-polymerized styrene-butadiene rubber is 30-80, the glass transition temperature is -50℃ to 0℃, and the modification rate of polar functional groups of the polymer is >90%. The nitrogen content of the star-shaped functionalized solution-polymerized styrene-butadiene rubber is 2000-3500 mg / kg of solution-polymerized styrene-butadiene rubber.

[0059] Specifically, the product structure design of the star-shaped functionalized solution-polymerized styrene-butadiene rubber polymer is as follows (in-chain and end-chain functionalization of starfish-shaped chains): Star-shaped functionalized solution-polymerized styrene-butadiene rubber is a random copolymer of butadiene and styrene, and has a unique cyclic multi-star arm structure. The active center is retained at the center of the star-shaped molecular chain (i.e., the star nucleus), and in-chain functionalization can be achieved through functionalizing agents; after coupling, each star arm of the star-shaped functionalized solution-polymerized styrene-butadiene rubber carries polar functional groups at its end. These polar functional groups come from front-end modifiers, including N,N-dimethylamine and diphenylamine compounds.

[0060] The star-shaped functionalized solution-polymerized styrene-butadiene rubber (SBR) contains 5-95% styrene monomer by mass, most preferably 30%; 6-90% vinyl structural units in all butadiene structural units, preferably 13-60%, most preferably 40%; Mooney viscosity of 30-80, preferably 55-65, most preferably 65; and a glass transition temperature of -50~0℃, preferably -40~-15℃, most preferably -30℃. The polar functional group modification rate of the polymer is >90%, preferably 97%. The nitrogen content is 2000-3500 mg / kg of solution-polymerized SBR, preferably 2500-3200 mg / kg of solution-polymerized SBR.

[0061] The molecular weight distribution spectrum obtained by GPC analysis generally exhibits a three-peak distribution. The number average molecular weight of the first polymer peak is 80,000-150,000 g / mol, preferably 90,000-120,000 g / mol, and most preferably 100,000 g / mol; the molecular weight distribution of the first polymer peak is 1.0-1.5, preferably 1.05-1.1. The number average molecular weight of the second polymer peak is 240,000-450,000 g / mol, most preferably 300,000 g / mol; the molecular weight distribution of the second polymer peak is 1.0-1.5, preferably 1.1-1.3; the peak area ratio of the second polymer peak is 20-40%, preferably 35%. The number average molecular weight of the third polymer peak is 480,000-900,000 g / mol, most preferably 600,000 g / mol; the molecular weight distribution of the third polymer peak is 1.0-1.5, preferably 1.1-1.3; the peak area ratio of the third polymer peak is 40-60%, preferably 55%.

[0062] The in-chain functionalizing agents of star-shaped solution-polymerized styrene-butadiene rubber include: p-dimethylaminobenzophenone, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

[0063] Embodiments of the present invention provide a method for preparing star-shaped functionalized solution-polymerized styrene-butadiene rubber, comprising the following steps:

[0064] S1: Prepare a clean, dry glass bottle and purge it with nitrogen to remove oxygen. Under a sealed, inert atmosphere, add 900g cyclohexane, 30g styrene, 70g butadiene, and 5ml of a 10g / L THF cyclohexane solution. Then, add 0.6ml of a 0.5mol / L n-butyllithium cyclohexane solution below 20°C to remove impurities. Next, in another clean, dry glass bottle purged with nitrogen, premix 2.0ml of a 0.5mol / L n-butyllithium solution and 2.1ml-2.4ml of a 0.5mol / L cycloheximine (or other front-end modifier) ​​solution and react for 2min-200min at -78°C to obtain the functionalized initiator. Subsequently, add the monomer solution at 60°C and stir to carry out the polymerization reaction for 10min-200min, continuing stirring to proceed to the next coupling reaction.

[0065] S2: Add 2.4ml-21ml of 0.5mol / L DVB coupling agent solution to the reaction system and stir rapidly at 60℃ for 5min-120min to generate a star-shaped polymer with an active star core and polar functional groups at the end of each star arm.

[0066] S3: Add 2.2ml-10.5ml of 0.5mol / L mid-chain functionalizing agent to form a multifunctional star polymer with end-chain and mid-chain functionalization.

[0067] S4: Add an antioxidant solution of 1520 / 1076 in a 1:1 mass ratio to the polymer solution at 0.6% of the dry adhesive content. After concentrating and removing 80% of the solvent using a rotary evaporator, place the concentrated solution in an enamel tray and vacuum dry it in a vacuum oven at 70°C for 24 hours to obtain a colorless and transparent sample.

[0068] Figure 1 A schematic diagram of the reaction principle of the star polymer provided in the embodiments of the present invention; Figure 2 The in-chain functionalization mechanism of star polymers provided in the embodiments of the present invention.

[0069] I. Analytical and Detection Methods

[0070] Mooney viscosity test: Preheat a sample weighing more than 15 grams for 1 minute, then measure at 100°C for 4 minutes using an MV-2000 manufactured by ALPHA Technologies.

[0071] Molecular weight (number average molecular weight, weight average molecular weight, polydispersity index): measured by gel permeation chromatography (GPC) at 40°C. Polystyrene monodisperse standard was used as the standard sample for molecular weight calculation; THF was used as the mobile phase at a flow rate of 1 ml / min.

[0072] Modification rate analysis method: Using chain-modified styrene-butadiene rubber (SBR) as the sample, the content of chain-modified SBR components is determined by utilizing the characteristic that chain-modified SBR components adsorb onto a GPC column packed with silica-based gel. The adsorption amount of chain-modified SBR components on the silica column is determined by the difference in chromatograms (the difference between the chromatogram obtained by measuring the sample solution containing the sample and the low molecular weight polystyrene internal standard using a polystyrene-based gel column and the chromatogram obtained by measuring using a silica-based column). GPC analysis sample preparation method: 10 mg of sample and 5 mg of standard low molecular weight polystyrene internal standard are dissolved in 20 ml of tetrahydrofuran. Polystyrene-based column GPC determination conditions: THF is used as the eluent, and 200 μL of sample is injected into the device for determination. A guard column (TSK guard column HHR-H, manufactured by Tosoh Corporation) and three columns (TSK gelSuper Multipore HZ-H, manufactured by Tosoh Corporation) are connected together. Chromatograms were obtained using an RI detector (HLC8020, manufactured by Tosoh Corporation) at a column oven temperature of 40°C and a THF flow rate of 1.0 mL / min. For silica-based column GPC assays, 200 μL of the sample was injected into the apparatus using THF as the eluent. Three silica-based columns (Zorbax PSM-1000S, PSM-300S, and PSM-60S) were connected in series, with a DIOL 4.6 × 12.5 mm 5 micron guard column connected upstream. Chromatograms were obtained using an RI detector (HLC8020, manufactured by Tosoh Corporation) at a column oven temperature of 40°C and a THF flow rate of 0.5 mL / min. The method for calculating the modification rate (content of modified styrene-butadiene rubber in the chain) is as follows: For chromatograms using polystyrene columns, the peak area is set to 100, the peak area of ​​the sample is set to P1, and the peak area of ​​standard polystyrene is set to P2. For chromatograms using silica columns, the peak area is set to 100, the peak area of ​​the sample is set to P3, and the peak area of ​​standard polystyrene is set to P4. The modification rate (%) is then calculated using the following formula:

[0073] Modification rate (%) = [1 - (P2 × P3) / (P1 × P4)] × 100

[0074] (Where, P1 + P2 = P3 + P4 = 100)

[0075] Definition of polymer modification rate: The polymer modification rate index represents the mass fraction of all polymer molecular chains that carry polar functional groups at the end groups or star-cores of the molecular chains.

[0076] Nuclear magnetic resonance (NMR) analysis: The microstructure of the samples was analyzed using a Brucker 600 MHz superconducting Fourier transform NMR spectrometer. The ¹H spectrum was observed at 600 MHz, and the ¹³C spectrum at 150.9 MHz. CDCl₃ was used as the solvent, TMS as the internal standard, and the experimental temperature was 20 °C. This method can be used to analyze the styrene and vinyl content of styrene-butadiene rubber (SBR).

[0077] DSC thermal property analysis: A sample of 15-20 mg was taken, and the temperature test range was -120℃ to 120℃. Thermal history was eliminated before the formal test. The heating and cooling rates were 10℃ / min, and the dwell time at the highest and lowest temperatures was 5 min. This method can be used to analyze the glass transition temperature of styrene-butadiene rubber.

[0078] Conversion rate test method: A small portion of the polymer solution was removed from the reactor using a specially designed cylindrical container. The total weight (A) of the cylindrical container containing the polymer solution was then measured. The polymer solution in the cylindrical container was then transferred to an aluminum tray, and the weight (B) of the cylindrical container after removing the polymer solution was measured. The aluminum tray containing the polymer solution was then dried in a vacuum oven at 100°C for at least 180 minutes until the polymer was completely dry and transparent. Finally, the weight (C) of the dried polymer was measured, and the polymer conversion rate was calculated using the following mathematical formula:

[0079]

[0080] Nitrogen content analysis method: N content was measured using the NSX analytical method with a trace nitrogen quantitative analyzer (NSX-2100H). Specifically, the trace nitrogen quantitative analyzer (autosampler, horizontal furnace, PMT & Nitrogen detector) was turned on, the carrier gas flow rate was set to 250 ml / min for Ar, 350 ml / min for oxygen, and 300 ml / min for ozone generator, and the heater was set to 800°C. The analyzer was left to stabilize for approximately 3 hours. After stabilization, calibration curves were prepared using nitrogen standards (AccuStandard S-22750-01 to 5 ml) at concentrations of 5 ppm, 10 ppm, 50 ppm, 100 ppm, and 500 ppm, and the area corresponding to each concentration was obtained. Then, a ceramic boat containing 20 mg of sample was placed in the analyzer's autosampler and measured to obtain the area. The N content was calculated using the thus obtained sample area and calibration curves.

[0081] Silicon content analysis: The silicon content was measured using inductively coupled plasma optical emission spectrometry (ICP-OES: Optima 7300DV) via ICP analysis. Specifically, approximately 0.7 g of sample was added to a platinum crucible, followed by approximately 1 ml of concentrated sulfuric acid (98% by mass, electronic grade). The mixture was heated at 300°C for 3 hours and then burned in an electric furnace (Thermo Scientific, Lindberg Blue M) following steps 1 to 3:

[0082] Step 1: Initial temperature 0℃, rate (temperature / hour) 180℃ / hour, temperature (holding time) 180℃ (1 hour);

[0083] Step 2: Initial temperature 180℃, rate (temperature / hour) 85℃ / hour, temperature (holding time) 370℃ (2 hours);

[0084] Step 3: Initial temperature 370℃, rate (temperature / hour) 47℃ / hour, temperature (holding time) 510℃ (3 hours);

[0085] Add 1 ml of concentrated nitric acid (48% by mass) and 20 μL of concentrated hydrofluoric acid (50% by mass) to the residue, seal the platinum crucible and shake for at least 30 minutes, add 1 ml of boric acid to the sample, store at 0°C for at least 2 hours, dilute with 30 ml of ultrapure water, and incinerate.

[0086] II. Summary of Experimental Data

[0087] Table 1. Data results of Examples 1-2 and Comparative Examples 1-5

[0088]

[0089] The star-shaped functionalized solution-polymerized styrene-butadiene rubber of this embodiment has the following advantages:

[0090] 1. The star-shaped functionalized solution-polymerized styrene-butadiene rubber has a higher modification rate. It can be seen that the combination of the "functionalized initiator preparation technology" and "star core chain modification technology" of the present invention significantly improves the molecular chain polarity of solution-polymerized styrene-butadiene rubber, which can significantly improve the interfacial bonding force between SSBR and silica.

[0091] 2. The fact that the star-shaped functionalized solution-polymerized styrene-butadiene rubber has a higher nitrogen content shows that the functionalization technology of this invention can give SSBR a higher degree of functionalization, thus significantly improving the interfacial bonding force between SSBR and silica.

[0092] 3. The combination of coupling technology and functionalization technology in this invention significantly improves the molecular weight and Mooney viscosity of star-functionalized solution-polymerized styrene-butadiene rubber, which can significantly improve the strength of rubber products.

[0093] III. Vulcanized Rubber Compound Formulation and Manufacturing Conditions

[0094] The compounding formulations for vulcanized rubber are shown in Table 2 (the raw material amounts in Table 2 are expressed as parts by weight based on 100 parts by weight of styrene-butadiene rubber):

[0095] Table 2. Compound Formulations for Vulcanized Rubber

[0096]

[0097] Vulcanized rubber is prepared through a first-stage mixing and a second-stage mixing process. In the first-stage mixing, rubber, silica, organosilane coupling agent (X50S, Evonik), processing oil (TDAE), zinc oxide (zinc white), stearic acid, antioxidant (TMQ(RD)) (2,2,4-trimethyl-1,2-dihydroquinoline polymer), anti-aging agent (6PPD (dimethylbutyl-N-phenyl-phenylenediamine) and microcrystalline wax) are mixed using a Banbury mixer equipped with a temperature control device. In this case, the initial temperature of the mixing unit is controlled at 70°C, and after mixing, the first compound is obtained at a discharge temperature of 145°C. In the second stage of compounding, the first compound was cooled to room temperature, and then the first compound, sulfur, rubber accelerator (DPD (diphenylguanidine)), and vulcanization accelerator (CZ (N-cyclohexyl-2-benzothiazolylsulfinamide)) were added to the mixer and mixed at a temperature below 100°C to obtain the second compound. Finally, vulcanized rubber samples were prepared by crosslinking in a flat vulcanizing machine at 160°C for 20 minutes.

[0098] IV. Evaluation Methods for the Application Performance of Vulcanized Rubber

[0099] 1. Tensile Testing of Vulcanized Rubber: The tensile strength and tensile stress at 300% elongation (300% constant elongation) were measured according to ASTM 412 tensile testing method. For this purpose, a Universal Test Machine 4204 manufactured by Instron was used, and the tensile strength, modulus, and elongation were measured at room temperature at a tensile rate of 50 cm / min.

[0100] 2. Dynamic Mechanical Properties Testing of Vulcanized Rubber: A dynamic mechanical analyzer manufactured by TA was used. The loss factor Tanδ was measured for each sample after deformation at a frequency of 10 Hz in deformation mode and a measurement temperature range of -60°C to 80°C. The Payne effect is represented by the difference between the minimum and maximum values ​​within the deformation range of 0.28% to 40%. A lower Payne effect indicates higher filler dispersibility. Increasing the loss factor at 0°C improves wet skid resistance, and decreasing it at 60°C reduces hysteresis loss and rolling resistance, thus increasing fuel economy. A decrease in the loss modulus at 60°C reduces internal heat generation in the rubber, reduces hysteresis loss, and improves dynamic performance.

[0101] 3. DIN abrasion resistance test of vulcanized rubber: For each vulcanized rubber sample, a DIN abrasion test was performed based on ASTM D5963 and displayed by the DIN loss index (volume index: ARIA (abrasion resistance index, method A)).

[0102] Table 3. Evaluation results of the application performance of vulcanized rubber (analytical values)

[0103]

[0104] Comparing the Mooney viscosity of the compound rubbers, all compound rubbers showed an increase in Mooney viscosity compared to the raw rubber. However, the increase in Mooney viscosity of the compound rubbers in Comparative Examples 2-4 was not significant compared to the raw rubber, and was much lower than that in Examples 1-2. This indicates that the innovative combination of the "functionalized initiator technology," "DVB active coupling technology," and "back-end functionalized chain modification technology" of this invention significantly improves the compounding and processing performance of solution-polymerized styrene-butadiene rubber. It exhibits the best mixing and dispersion properties between the rubber and fillers, is easy to incorporate, and generates low heat during the compounding process, resulting in the lowest degree of pre-vulcanization of the compound rubber. The resulting data characteristic is that the Mooney viscosity of the compound rubber does not increase significantly compared to the Mooney viscosity of the raw rubber.

[0105] The 300% elongation at break, elongation at break, and tensile strength of Examples 1-2 were significantly higher than those of Comparative Examples 1-3, which is related to the molecular weight and Mooney viscosity.

[0106] The elongation at break and tensile strength of Examples 1-2 are higher than those of Comparative Examples 4-5 because the molecular chains of Examples 1-2 are more functionalized. The star-shaped functionalized solution-polymerized styrene-butadiene rubber exhibits the best mixing and dispersion properties with the filler, resulting in the most complete filler-polymer network and the best mechanical properties in the prepared vulcanized rubber. Therefore, the star-shaped functionalization modification technology of this invention has significant advantages.

[0107] A higher abrasion resistance index indicates better abrasion resistance of the vulcanized rubber. The abrasion resistance indices of Examples 1-2 are significantly higher than those of Comparative Examples 1-5, indicating that the functionalization modification technology of the star polymer improves the abrasion resistance of SSBR.

[0108] A higher 0°C loss factor indicates higher wet grip and traction of the vulcanized rubber. The 0°C loss factors of Examples 1-2 are all >0.3, which are higher than those of Comparative Examples 1-5. Therefore, the star-shaped functionalized SSBR of the present invention has excellent traction and wet grip on ice surfaces.

[0109] A lower 60°C loss factor indicates lower rolling resistance of the vulcanized rubber, which can improve fuel economy when used in tires. The 60°C loss factors of Examples 1-2 are all below 0.1000, significantly lower than Comparative Examples 1-2, and not significantly different from Comparative Examples 3-5. This indicates that the star-shaped functionalization modification technology of the present invention, compared with traditional chain-end functionalization technology and star-shaped branching technology, mainly improves the 0°C loss factor, but has a relatively small impact on the 60°C loss factor. The star-shaped functionalization modification technology of the present invention significantly reduces the hysteresis loss of SSBR and exhibits excellent dynamic performance.

[0110] A lower loss modulus at 60°C indicates lower internal heat generation and better dynamic performance of the vulcanized rubber, which can improve fatigue resistance when used in tires. The loss modulus at 60°C in Examples 1-2 is lower than that in Comparative Examples 1-5, indicating that the star-functionalized solution-polymerized styrene-butadiene rubber of the present invention has lower internal heat generation and better fatigue resistance. Similarly, the loss modulus at 60°C in Comparative Examples 3-5 is lower than that in Comparative Example 1, indicating that the chain-end modification technology of tertiary amine groups and siloxane groups can also improve the dynamic performance and fatigue resistance of SSBR, but the improvement effect is slightly lower than that of the star-functionalized modification technology of the present invention.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing star-shaped functionalized solution-polymerized styrene-butadiene rubber, characterized in that, The preparation method includes the following steps: Under S10 and inert atmosphere conditions, in an organic solvent, butadiene and styrene are used as polymerization monomers, and a substance obtained by premixing alkyl lithium and a front-end modifier is used as a functionalization initiator for solution polymerization to obtain a polymer precursor. S20. An active coupling agent is added to the polymer precursor to react and obtain a star-shaped polymer with an active star core and polar functional groups at the end of each star arm. S30. Add the functionalizing agent to the star polymer and react to obtain the star-functionalized solution-polymerized styrene-butadiene rubber with both end-chain and mid-chain functionalization. The functionalizing agent includes at least one of p-dimethylaminobenzophenone, diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. The active coupling agent is a bifunctional conjugated diene compound; The front-end modifier includes at least one of N,N-dimethylamine, diphenylamine, cycloheximine, and pyrrolidine; The active coupling agent includes at least one of divinylbenzene and 1,4-diisopropenylbenzene; The molar ratio of the functionalized initiator, the active coupling agent, and the functionalized reagent is 1:(2.0-6.0):(0.8-1.6). The active group and bifunctional characteristics of the functionalizing agent undergo a coupling reaction with the active lithium site at the end of the star polymer. The functionalizing agent acts as a "core" to connect multiple polymer chains, forming the unique cyclic multi-star arm structure of the star-functionalized solution-polymerized styrene-butadiene rubber. Polar functional groups are introduced into the end group and the core of each "star arm" of the star-shaped functionalized solution polystyrene-butadiene rubber. Under temperature conditions ranging from -78°C to 30°C, the dissociative agent and the front-end modifier are first premixed at a molar ratio of (1.0-1.5):1, and then the front-end modifier and the alkyl lithium are premixed at a molar ratio of 1:(1.0-1.3) to obtain the functionalized initiator; the dissociative agent is tetrahydrofuran.

2. The preparation method according to claim 1, characterized in that, The alkyl lithium includes at least one of methyl lithium, ethyl lithium, isopropyl lithium, n-butyl lithium, tert-butyl lithium, and sec-butyl lithium.

3. The preparation method according to claim 1, characterized in that, S10 specifically includes: S11. Under a closed, inert atmosphere, the organic solvent and the polymeric monomer are mixed at a mass ratio of (80-95):(5-20) to obtain a monomer solution. S12. Under temperature conditions ranging from -78℃ to 30℃, the dissociative agent and the front-end modifier are premixed at a molar ratio of (1.0-1.5):1 for 2 min-10 min, and then the front-end modifier and the alkyl lithium are premixed at a molar ratio of 1:(1.0-1.3) for 2 min-200 min to obtain the functionalized initiator. S13. The functionalized initiator is added to the monomer solution at a temperature of 0℃-60℃ to initiate polymerization. The reaction time is 10min-200min to obtain the polymer precursor.

4. The preparation method according to claim 3, characterized in that, Following S11, the following is also included: A cyclohexane solution of the alkyllithium is added to the monomer solution at a temperature of 0℃-20℃. The mass ratio of the alkyllithium to the cyclohexane is (10-20):(80-90).

5. The preparation method according to claim 1, characterized in that, S20 specifically includes: The cyclohexane solution of the active coupling agent was added to the polymer precursor and stirred and mixed at a temperature of 0℃-60℃ for a reaction time of 5min-120min to obtain the star-shaped polymer with an active star core and polar functional groups at the end of each star arm. The mass ratio of the active coupling agent to the cyclohexane is (1-3):(97-99).

6. The preparation method according to claim 1, characterized in that, The preparation method further includes: S40. Add an antioxidant to the star-shaped functionalized solution-polymerized styrene-butadiene rubber, concentrate it, and then vacuum dry it to obtain the finished rubber.

7. A star-shaped functionalized solution-polymerized styrene-butadiene rubber, characterized in that, The star-shaped functionalized solution-polymerized styrene-butadiene rubber is prepared by the preparation method according to any one of claims 1-6.

8. The star-shaped functionalized solution-polymerized styrene-butadiene rubber according to claim 7, characterized in that, The star-shaped functionalized solution-polymerized styrene-butadiene rubber uses butadiene and styrene as polymerizing monomers. The mass fraction of the styrene monomer in the star-shaped functionalized solution-polymerized styrene-butadiene rubber is 5%-95%, and the mass fraction of the vinyl structural units in the butadiene structural units is 6%-90%. The star-shaped functionalized solution-polymerized styrene-butadiene rubber has a Mooney viscosity of 30-80, a glass transition temperature of -50℃ to 0℃, and a polymer polar functional group modification rate of >90%. The nitrogen content of the star-shaped functionalized solution-polymerized styrene-butadiene rubber is 2000-3500 mg / kg.

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