A method for long-chain branching modification of rare-earth isoprene rubber and / or butadiene isoprene rubber

Abstract

The present application relates to the field of polymer manufacturing, and particularly relates to a long-chain branched modification method of rare earth isoprene rubber and / or butadiene rubber, comprising the following steps: S1. performing solution polymerization of isoprene and / or butadiene and isoprene in a non-polar solvent in the presence of a rare earth catalyst to obtain a glue solution containing active polymer molecular chains; S2. when the conversion rate of the polymerization reaction reaches 95% or more, adding a compound branched modifier to the glue solution to perform a branched reaction; wherein the compound branched modifier comprises at least one of a chloride and an alkyl halide and at least one selected from ether compounds and tertiary amine compounds. The branched modifier used in the present application has a strong branching effect, and has good solubility so as to achieve uniform mixing at a molecular level in the glue solution, significantly alleviates the gel side reaction, reduces the gel content, narrows the molecular weight distribution, significantly improves the raw rubber performance, and improves the product uniformity.

Description

Technical Field

[0001] This invention relates to the field of polymer manufacturing, and more particularly to a method for long-chain branching modification of rare earth isoprene rubber and / or butadiene rubber. Background Technology

[0002] Rare earth neodymium-based isoprene rubber and pentadiene rubber, as high-end synthetic rubbers, are widely used in high-performance tires, especially in tread and sidewall components with stringent requirements for low-temperature performance, rolling resistance, and wear resistance, due to their high cis structure, narrow molecular weight distribution, good raw rubber strength, and excellent dynamic properties of vulcanized rubber. However, their highly linear molecular chain structure, determined by specific catalyst systems, while bringing excellent final product performance, also generates a series of ongoing challenges in synthesis, processing, and application. In the linear molecular chain state, the polymer has a large hydrodynamic volume in a good solvent, resulting in a significantly higher viscosity of the polymerized rubber solution. This not only increases the energy consumption for material transportation and stirring but also places higher demands on the design and process control of the reactor. In the subsequent compounding process, linear rubber often exhibits slow feeding and requires improvement in filler dispersion uniformity, leading to a higher Mooney viscosity in the compound, increasing processing energy consumption and equipment burden. Furthermore, the linear molecular chain's ability to resist cold flow deformation is relatively insufficient, making the raw rubber prone to adhesion and deformation during storage and transportation, increasing the complexity and cost of warehousing and logistics management.

[0003] To systematically improve the processing performance and storage stability of rare earth rubber while retaining its inherent advantages such as high cis structure, low heat generation, and high abrasion resistance, introducing controllable long-chain branched structures into the molecular chain has become a clear and ongoing research direction in this field. The industry generally hopes to reduce the hydrodynamic volume of the polymer in solution by constructing a moderately branched structure to alleviate the problem of high viscosity of the rubber solution, improve its mixing behavior in the internal mixer to promote filler dispersion, and endow the raw rubber with better cold flow resistance. To achieve this goal, domestic and foreign research institutions and enterprises have proposed various technical solutions based on post-modification using externally added chemical branching agents over the years.

[0004] Early technological explorations focused on using highly reactive small-molecule compounds. For example, disulfur dichloride was used as a branching agent, utilizing its sulfur atoms to undergo addition reactions with unsaturated double bonds on polymer molecular chains, thereby bridging different molecular chains to form branching points. While this method can effectively improve Mooney viscosity and cold flow resistance, in practical applications, the intense reactivity of this branching agent makes it difficult to achieve instantaneous uniform dispersion in high-viscosity adhesives. Excessively high local concentrations can easily trigger uncontrollable cross-linking side reactions, leading to an increase in gel content in the product, which in turn impairs the processability and final mechanical properties of the material. Simultaneously, this substance is prone to side reactions with residual monomers and other components in the system, reducing its effective utilization rate as a branching agent. Furthermore, its irritating odor and toxicity also bring additional concerns to production operations and environmental protection. Another branching agent previously reported, phosphorus trichloride, while also possessing strong branching capabilities, is highly corrosive and toxic, posing a severe challenge to the safety of production equipment and personnel protection. Its violent reaction with water also increases the stringency of process control.

[0005] Subsequent technological developments attempted to utilize metal chlorides, such as tin tetrachloride. These substances exhibited relative advantages in terms of controllability of the branching reaction, gel inhibition, and cost, and were classified as low-toxicity substances. However, new problems emerged in industrial practice. Solution polymerization of rare earth rubber is typically carried out in non-polar alkane solvents such as n-hexane and cyclohexane, while highly polar metal chlorides like tin tetrachloride do not exhibit ideal compatibility and solubility in these solvents. This insufficient solubility makes it difficult for the branching agent to be uniformly dispersed at the molecular scale throughout the entire adhesive system, easily leading to microscopic concentration inhomogeneities. This inhomogeneity causes the branching reaction to proceed too rapidly in localized areas of the adhesive, also resulting in fluctuations in gel content and a broadening of the molecular weight distribution, affecting the batch-to-batch uniformity and performance stability of the product. Furthermore, these branching agents may interact with residual catalyst components, consuming their effective content to some extent. To achieve the desired branching effect, additional dosage is sometimes required, which not only increases costs but may also have long-term effects on equipment materials.

[0006] On the other hand, in pursuit of more precise molecular structure design or to avoid some of the drawbacks of the aforementioned small-molecule branching agents, some research has turned to more complex organic branching agents, such as specifically designed star compounds, polyene substrates, or functionalized polymers. These branching agents may theoretically provide more controllable branching structures, but their synthetic routes are usually complex, raw material sources are limited, and customization costs are high, which largely limits their economic viability and feasibility in large-scale industrial production.

[0007] In summary, existing technologies have proposed various long-chain branching modification pathways to address the shortcomings of linear molecular chains in rare earth isoprene and butyl pentadiene rubber, but each faces different limitations. Whether it's the numerous side reactions, difficulty in uniformity control, and significant safety and environmental concerns associated with schemes based on highly reactive small molecule compounds, or the challenges of poor dispersion uniformity in nonpolar systems encountered with schemes based on metal chlorides, or the high costs and complex synthesis processes associated with schemes based on complex organic molecules, all indicate that this field still needs to find a new modification method that achieves a better balance between reaction controllability, product uniformity, industrial feasibility, and overall cost. An ideal solution should be able to achieve good dispersion and uniform reaction of the branching agent in common nonpolar polymerization systems, effectively suppress gel formation, while also being simple in process, using readily available raw materials, and easily scalable for stable production. Summary of the Invention

[0008] This application aims to overcome the shortcomings of existing long-chain branching modification methods that are not efficient, controllable, and suitable for industrial application. Therefore, it provides a long-chain branching modification method for rare earth isoprene rubber and / or butadiene rubber to overcome the above-mentioned shortcomings.

[0009] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a method for long-chain branching modification of rare earth isoprene rubber and / or butadiene-pentadiene rubber, comprising the following steps: S1. In the presence of a rare earth catalyst, isoprene and / or butadiene are subjected to solution polymerization in a nonpolar solvent to obtain a gel containing active polymer molecular chains. S2. When the polymerization conversion rate reaches 95% or more, a compound branching agent is added to the adhesive to carry out a branching reaction; The compound branching agent comprises component A and component B; Component A is selected from at least one of chlorides and alkyl halides; Component B is selected from at least one of ether compounds and tertiary amine compounds; The molar ratio of component B to component A is 0.5:1 to 2.0:1.

[0010] As described in the background section, existing technologies for the branching modification of long-chain rare earth rubber employ several methods: Highly active small-molecule branching agents, such as disulfide dichloride, while capable of introducing branched structures, exhibit violent and uncontrollable reactions, easily leading to localized gelation, impairing product uniformity, and posing production and environmental burdens due to their toxicity and odor. While metal chlorides like tin tetrachloride offer advantages in reaction controllability and cost, their poor solubility in non-polar polymerization solvents like hexane directly results in uneven dispersion in the adhesive solution, similarly causing excessively vigorous localized branching reactions and product performance fluctuations, and potentially leading to additional consumption due to reactions with residual catalysts. Furthermore, some structurally complex customized organic branching agents are difficult to synthesize and costly, failing to meet the economic and stability requirements of industrial production. These shortcomings collectively point to an unresolved industry dilemma: how to achieve efficient, uniform dispersion and controllable reaction of branching agents in common non-polar solution polymerization systems, thereby stably obtaining branched rubber products with low gel content, uniform structure, and significantly improved processing performance.

[0011] To address the aforementioned contradictions, this technical solution employs a branching agent system composed of a specific component A and component B. Component A is selected from chlorides and alkyl halides. These substances are known to possess a certain ability to initiate branching between polymer molecules; however, when used alone, as illustrated by the example of tin tetrachloride in the background section, their dissolution and dispersion in nonpolar solvents are major obstacles. Therefore, the key innovation of this application lies in the introduction of component B, namely, an ether or tertiary amine compound. The selection of these compounds is not arbitrary; their oxygen or nitrogen atoms possess lone pairs of electrons. When compounded with component A and used within a specific molar ratio range (0.5:1 to 2.0:1), component B coordinates with the empty orbitals of the central atom of component A through its lone pairs of electrons. This interaction generates multiple synergistic effects, fundamentally altering the reaction system environment.

[0012] First, the most direct effect is a significant improvement in the solubility and dispersibility of component A in non-polar solvents such as n-hexane. Component B, acting as a "solventizing" or "composting" medium, effectively carries component A, which is prone to aggregation or precipitation, into the solution and disperses it uniformly throughout the entire gel medium. This allows the branching agent to contact the active polymer chains at a scale closer to the molecular level, avoiding excessively high local concentrations caused by uneven physical dispersion. Therefore, the branching reaction can proceed in a broader and more uniform reaction field, significantly suppressing gelation caused by excessively rapid or excessive local reactions from the source, laying the foundation for obtaining branched products with more controllable molecular weight distribution and lower gel content.

[0013] Secondly, the introduction of component B also has a positive impact on the chemical reaction environment of the system. In the later stages of solution polymerization, residual active rare-earth catalyst centers may still exist in the system. Component B can also coordinate with these active centers, and this coordination reduces the residual catalyst activity to some extent, or in other words, "passivates" some overly active catalytic sites during the branching reaction stage. This not only reduces the unproductive side reaction consumption between component A and the residual catalyst, allowing component A to be more effectively dedicated to the branching reaction with the polymer molecular chains and improving the utilization rate of the branching agent, but also provides the possibility for more precise control of the process and extent of the branching reaction.

[0014] In addition, the branching reaction is strictly set when the polymerization conversion rate reaches 95% or more, which ensures that the polymer molecular chain has basically grown completely and the main molecular structure tends to be stable. At this time, the introduction of branching points is conducive to the formation of long-chain branching with a clear structure, rather than premature intervention in the polymerization process that leads to structural disorder.

[0015] This "A+B" compounding and synergistic approach to specific process steps yields consistent and significant technical benefits. Specifically, addressing the issues of uneven reaction and high gel content caused by poor dissolution and dispersion of branching agents in existing technologies, this invention achieves uniform dispersion of the branching agent in the liquid by introducing component B. This makes the branching reaction stable and controllable, significantly reducing the gel content in the product and improving batch-to-batch consistency. Furthermore, addressing the challenges of performance control and high costs due to numerous side reactions and low branching agent utilization, component B regulates the residual activity of the catalyst and enhances the efficiency of component A. This reduces the amount of component A required while achieving more efficient branching, making the control of key processing properties such as Mooney viscosity of the final product more precise and reliable. Ultimately, these improvements at the molecular and reaction process levels are directly reflected in the macroscopic properties of rubber products: the viscosity of the rubber solution is effectively reduced, improving transport and mixing performance; the compounding and processing performance of the raw rubber is enhanced, and fillers are more easily and uniformly dispersed; simultaneously, due to the introduction of a moderately branched structure, the cold flow resistance of the raw rubber is significantly enhanced, making it easier to store and transport. Furthermore, the components A and B used in the entire technical solution are mostly common chemical raw materials, widely available, with relatively controllable costs, and a simple compounding process, requiring no harsh reaction conditions or complex synthesis steps, demonstrating good potential for industrial application.

[0016] In summary, this application, by compounding specific types of chlorides or alkyl halides with ethers or tertiary amines and controlling their proportions and addition timing, creatively utilizes the coordination synergy between the two to systematically solve several interrelated technical problems in nonpolar solvent systems, such as poor solubility and dispersibility of branching agents, difficulty in controlling reaction uniformity, numerous side reactions, and interference from residual catalysts. Thus, without excessively increasing costs and process complexity, it achieves effective control over the long-chain branching modification process of rare earth isoprene rubber and butyl pentylene rubber, resulting in products with superior overall performance.

[0017] Preferably, component A is selected from at least one of silicon tetrachloride, methyl silicon trichloride, ethyl silicon trichloride, n-propyl silicon trichloride, isopropyl silicon trichloride, n-butyl silicon trichloride, isobutyl silicon trichloride, tert-butyl silicon trichloride, sec-butyl silicon trichloride, octyl silicon trichloride, germanium tetrachloride, methyl germanium trichloride, ethyl germanium trichloride, n-propyl germanium trichloride, isopropyl germanium trichloride, n-butyl germanium trichloride, isobutyl germanium trichloride, tert-butyl germanium trichloride, sec-butyl germanium trichloride, octyl germanium trichloride, tin tetrachloride, methyl tin trichloride, ethyl tin trichloride, n-propyl tin trichloride, isopropyl tin trichloride, n-butyl tin trichloride, isobutyl tin trichloride, tert-butyl tin trichloride, sec-butyl tin trichloride, and octyl tin trichloride.

[0018] Preferably, the ether compound in component B includes at least one of diethyl ether, dimethyl ether, methyl ethyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, ethyl tetrahydrofurfuryl ether, N,N-dimethyltetrahydrofurfurylamine, 2,2-bis(2-tetrahydrofuranyl)propane, anisole, ethylene oxide, and propylene oxide.

[0019] Preferably, the tertiary amine includes at least one of triethylamine, hexamethylenediamine, N-methylpiperidine, N-ethylpiperidine, N-methylcyclohexylimine, N-ethylcyclohexylimine, N,N-bis(3-dimethylaminopropyl)methylamine, and tri(3-dimethylaminopropyl)amine.

[0020] Preferably, the molar ratio of component B to component A is 0.8:1 to 1.5:1.

[0021] Preferably, the molar ratio of component B to component A is 0.95:1 to 1.05:1.

[0022] Preferably, in step S1, the rare earth catalyst comprises the following components: (i) Neodymium organic acids; (ii) Alkyl aluminum compounds; (iii) Halogenated compounds; (iv) An optional electron donor; (v) A coagulant inhibitor, wherein the coagulant inhibitor is a siloxane compound.

[0023] Preferably, the siloxane compound is selected from at least one of linear polysiloxanes, cyclic polysiloxanes, and cage-like polysilsesquioxanes.

[0024] In the field of solution polymerization of conjugated dienes (such as isoprene and butadiene), neodymium-based catalysts have been widely studied due to their ability to prepare polymers with high cis structures and properties close to those of natural rubber. They represent an important direction for the synthesis of high-performance isoprene, butadiene, and butylene-pentadiene rubbers. However, existing technologies generally face a challenging engineering problem: the exothermic reaction is concentrated, and the system viscosity is high, making it difficult to remove the heat of reaction evenly and promptly, easily leading to localized overheating of the reaction system. This localized overheating can not only affect the uniformity of the polymer molecular weight distribution but, more importantly, significantly exacerbates side reactions initiated by active centers, causing cross-linking of polymer chains and the formation of gel substances insoluble in the solvent. These gels gradually adhere to the reactor walls, agitators, and pipes, causing so-called "gelling" and blockage phenomena.

[0025] Therefore, how to fundamentally suppress or alleviate the gelation tendency in the polymerization process while maintaining the advantages of high activity and high orientation of neodymium catalysts, and achieve stable release of reaction heat and stable control of the process, thereby extending the continuous operation cycle of the device, has become a key bottleneck to promote the further industrial application of this technology.

[0026] Faced with this technical bottleneck, conventional improvement approaches by those skilled in the art often focus on screening existing catalyst main components (such as neodymium carboxylate, alkyl aluminum, and halogen-containing compounds), optimizing their proportions, or adjusting aging processes. However, these improvements are often minor tweaks within the existing framework, and their effectiveness in solving the gelation problem, which is fundamentally determined by reaction kinetics and heat and mass transfer characteristics, is limited.

[0027] Compared to existing technologies, the technical solution of this invention does not replace the existing ternary or quaternary system, but introduces a completely new fifth component with a specific function. The purpose of this component is very clear: to directly target the goal of "inhibiting gel formation." This invention discovers that the root cause of gel formation lies in undesirable chain transfer and cross-linking reactions caused by overly active centers or excessively high local concentrations and temperatures. Therefore, the approach of this invention shifts to how to regulate the state of the active centers or their microenvironment, thereby "passivating" their side-reaction-causing aspects while retaining their primary reactive activity for chain growth.

[0028] Following this approach, the technical solution involves introducing a class of siloxane compounds. These substances act as "coagulation inhibitors" or "regulators" in the polymerization system. Their core mechanism lies in their molecular structure's ability to coordinate with the neodymium active centers in the catalytic system. The introduction of these linear, cyclic, and cage-like siloxane compounds increases the steric hindrance of the neodymium active centers through their coordination complexation, thus stabilizing them. The significant steric hindrance effect of these siloxane coagulation inhibitors only allows small monomer molecules such as isoprene and butadiene to enter the shielded structure formed by the siloxane compounds and contact the neodymium active centers. This ensures the continuous chain growth reaction while maintaining controllable polymerization, effectively preventing the rapid accumulation of reaction heat, avoiding localized overheating, improving mass and heat transfer within the reactor, and thus effectively mitigating gelation side reactions. Moreover, the technology of this invention also hinders the attack of residual double bonds of rubber macromolecules on neodymium active centers, further suppressing the probability of gelation side reactions, resulting in a significant reduction in gel content. This reduces the problems of adhesive sticking to the reactor inner wall, adhesive sticking to the agitator shaft, and blockage of adhesive pipelines that are prone to occur in subsequent industrial applications. It truly alleviates the need for frequent shutdowns for cleaning, reduces the loss of transition material and scrap material, significantly improves product quality consistency, saves a lot of manpower and material costs, and improves the stability of the production process and reduces potential production accident hazards.

[0029] Preferably, the linear polysiloxane is polydimethylsiloxane; The cyclic polysiloxane is selected from at least one of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and hexamethylcyclotrisiloxane; The cage-shaped polysilsesquioxane is selected from at least one of octamethyloctasilsesquioxane, octaphenyloctasilsesquioxane, and octavinyloctasilsesquioxane.

[0030] Preferably, the molar ratio of the anticoagulant to the neodymium element in the organic acid neodymium compound is 0.01:1 to 100:1.

[0031] Preferably, the branching reaction takes place over a period of 1 to 120 minutes.

[0032] Preferably, the compound branching agent is added in the form of a diluent, wherein the concentration of component A in the diluent is from 15 g / L to 750 g / L, and the amount of component A added is from 0.01 wt.% to 0.5 wt.% based on the total mass of the monomers.

[0033] Preferably, before adding the adhesive, component A and component B are mixed in an inert atmosphere and then diluted with the non-polar solvent to form a diluted solution of the compound branching agent.

[0034] Therefore, the present invention has the following beneficial effects: (1) The branching agent used in this invention has a strong branching effect and the branching reaction is controllable. The gelation tendency is relatively controllable. At the same time, the branching agent has a simple structure, a wide range of raw material sources, mature industrial products, and is inexpensive. Moreover, it is classified as a low-toxicity substance and is a non-flammable substance, so its danger is relatively low and it does not have an obvious unpleasant odor. (2) The branching agent B component of the present invention is readily soluble in n-hexane polymerization solvent. At the same time, the branching agent B component can also coordinate and complex with the empty orbitals of the central metal element of the branching agent A component through the lone pairs of oxygen or nitrogen atoms. Moreover, the branching agent B component does not undergo any side reactions with the branching agent A component. Therefore, the branching agent B component promotes the full dissolution of the branching agent A component in the n-hexane solvent, thereby effectively solving the problem that the branching agent A component is easy to precipitate in the n-hexane solution polymerization system, and thus ensuring the accuracy of the branching agent addition. (3) At the same time, the improved solubility of the branching agent in n-hexane also promotes the uniform mixing of the branching agent rare earth isoprene and butyl pentadiene rubber in the rubber solution at the molecular level, thereby significantly alleviating the gel side reaction, improving the poor uniformity of the product, reducing the gel content, controlling the narrowing of the molecular weight distribution, and significantly improving the performance of raw rubber. (4) Furthermore, the branching agent B component of this invention also “poisons” the rare earth catalyst, mainly by forming a severe “shielding steric hindrance” effect through coordination complexation with the neodymium active center. This destroys the activity of the rare earth catalyst and reduces the contact probability between the branching agent A component and the rare earth catalyst. Therefore, it can significantly reduce or even eliminate the need to add additional branching agent A component to inactivate the catalyst. The reduction in the amount of branching agent A component added is beneficial to the equipment. Attached Figure Description

[0035] Figure 1 The image shows the GPC diagram of the linear isoprene rubber prepared in step (S.2) of Example 1.

[0036] Figure 2 The image shows the GPC diagram of the branched isoprene rubber prepared in step (S.3) of Example 1. Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0038] The raw rubber prepared in the embodiments and comparative examples of this invention was tested using the following methods: I. Test Method Design and Test Process 1. Mooney viscosity test for raw rubber Test standard: Refer to GB / T 1232.1-2016 "Determination of unvulcanized rubber by disc shear viscometer - Part 1: Determination of Mooney viscosity".

[0039] 2. Gel content test The gel content level in polymer products was analyzed according to the method specified in the national standard SH / T 1050-2014.

[0040] 3. Viscosity test of 5% toluene solution Testing process: Solution preparation: Accurately weigh 0.500g of raw gum sample and dissolve it in 9.500g of toluene (to prepare a 5 wt.% solution). Stir magnetically at 23±2℃ for 48 hours to ensure complete dissolution (for highly gel samples, take the supernatant for testing). Instruments: Ubbelohde viscometer (capillary inner diameter: 0.8 mm), constant temperature water bath temperature set at 25±0.1℃; Test: Inject approximately 10 mL of the prepared solution into the viscometer and measure the time (t) it takes for the solution to flow through the upper and lower graduation marks. Calculation: Measure the flow time (t0) of pure toluene under the same conditions. The viscosity of the adhesive is characterized by relative viscosity η = t / t0; the lower the η value, the smaller the hydrodynamic volume of the polymer in the solution, indicating a more significant viscosity-reducing effect of branching. Each sample is tested once.

[0041] 4. Characterization of molecular weight and its distribution: An Agilent 1260 GPC instrument was used, with THF as the mobile phase, column temperature at 40℃, flow rate at 1 ml / min, and PS standard.

[0042] 5. Characterization of cis content: The cis content of the polymer was analyzed using a Bruker infrared spectrometer in accordance with the methods specified in national standards SH / T 1727-2017 and GB / T 7764-2017.

[0043] 6. Evaluation method for rubber compound vulcanization: Butadiene rubber and isoprene rubber shall be evaluated according to the methods specified in national standards GB / T 30918-2014 and GB / T 8660-2018.

[0044] 7. Tensile property analysis: The tensile properties of the polymer were analyzed according to the methods specified in the national standard GB / T 528-2009.

[0045] 8. Payne effect analysis conditions: A DMA analyzer was used, with analysis conditions of 50℃; 10Hz; 0.1%-10% strain / 10μm / min step. The smaller this index, the better the mixed dispersion state of the rubber filler, and the corresponding hysteresis performance will be improved.

[0046] 9. Wet skid performance analysis conditions: A DMA analyzer was used, and the analysis conditions were 0℃; 10Hz; 1% strain / 10μm / min step. The higher this index, the better the tire's wet skid performance.

[0047] 10. Rolling resistance analysis conditions: A DMA analyzer was used, and the analysis conditions were 50℃; 10Hz; 3% strain / 10μm / min step. The higher this index, the lower the tire rolling resistance.

[0048] Example 1 (S.1) 1.5 mmol neodymium neodecanoate, 30 mmol triisobutylaluminum, 4.5 mmol diethylaluminum chloride, 15 mmol linear polydimethylsiloxane (201-350 methyl silicone oil) and 30 mmol butadiene (as electron donor) were diluted with n-hexane to a total volume of 200 mL in another container and aged at 25 °C for 30 minutes to obtain the catalyst aging solution.

[0049] (S.2) In a 10L stainless steel polymerization reactor that has been treated to be anhydrous and oxygen-free, 6.0 kg of hexane (deeply dehydrated by molecular sieve) and 900 g of isoprene monomer (monomer concentration 13.04% wt.) were added, and the reactor temperature was controlled at 30℃. The catalyst aging solution was injected into the polymerization reactor to initiate the polymerization reaction, and the stirring speed was 120 rpm. After the polymerization reaction proceeded for 80 minutes, a sample was taken and the monomer conversion rate was measured to be 98.5%. Isoprene rubber was then precipitated with anhydrous ethanol and dried in a vacuum oven at 60℃ for 24 hours to obtain a linear isoprene rubber transparent block sample. The sample was subjected to Mooney viscosity analysis (41.0), TX80 branching degree analysis (2.1), and GPC molecular weight and molecular weight distribution analysis as follows: Figure 1 As shown (number-average molecular weight = 193,600 g / mol, weight-average molecular weight = 393,300 g / mol, molecular weight distribution = 2.02).

[0050] (S.3) At this point, the pre-prepared compound branching agent dilution is added to the reactor. This branching agent dilution is prepared by mixing 7.84 g of tin tetrachloride (component A) and 2.17 g of tetrahydrofuran (component B, A / B molar ratio of 1.0 / 1), and then diluting it with n-hexane to 100 mL (component A concentration of 78.4 g / L). The amount of branching agent added, based on component A, is 16.1 mL, which is 0.14% of the isoprene monomer mass. Simultaneously with the addition of the branching agent, the stirring speed is increased to 150 rpm, and the reaction continues at 30°C for 15 minutes. Subsequently, 10 mL of n-hexane solution containing 2 wt.% cyclohexanol is added to the reactor to terminate the reaction. After coagulation and drying, branched isoprene rubber is obtained. Samples are taken for Mooney viscosity analysis (53.6), TX80 branching degree analysis (4.8), and GPC molecular weight and molecular weight distribution analysis are as follows. Figure 2 As shown (number average molecular weight = 288,500 g / mol, weight average molecular weight = 586,100 g / mol, molecular weight distribution = 2.15), cis content analysis = 98.2%; Mooney analysis of the compounded rubber after mixing and vulcanization = 60.6%, tensile property analysis (300% tensile strength = 9.2 MPa, tensile strength = 18.4 MPa, elongation at break = 587%), Payne effect analysis ΔE' (50℃; 10Hz; 0.1%-10% strain / 1) =0.210MPa (0μm / min step), tanδ analysis of wet slip resistance at 0℃ ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) =0.445, tanδ analysis of rolling resistance at 50℃ ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) =0.103, gel content analysis =0.16%, viscosity analysis of 5% toluene solution at 25℃ =432cps.

[0051] Example 2 (S.1) 0.8 mmol neodymium neodecanoate, 16 mmol triisobutylaluminum, 2.4 mmol sesquiethylaluminum chloride, 4.0 mmol linear polydimethylsiloxane (201-1000 methyl silicone oil), and 16 mmol butadiene (as electron donor) were mixed with 100 mL n-hexane outside the reactor and aged at 40°C for 15 minutes to obtain the catalyst aging solution.

[0052] (S.2) In a 10L stainless steel polymerization reactor that has been treated to be anhydrous and oxygen-free, 5.8 kg of n-hexane, 522 g of butadiene, and 378 g of isoprene monomer (butadiene / isoprene mass ratio of 58 / 42) (monomer concentration = 13.4% wt.) were added, and the reactor temperature was controlled at 50℃. The aged liquid was injected into the polymerization reactor to initiate polymerization, and the stirring speed was 120 rpm. After the reaction proceeded for 70 minutes, the monomer conversion rate reached 96.2%. Isoprene rubber was then precipitated with anhydrous ethanol and dried in a vacuum oven at 60℃ for 24 hours to obtain a transparent isoprene rubber block sample. The sample was subjected to Mooney viscosity analysis = 47.0, TX80 branching degree analysis = 2.4, and GPC molecular weight and molecular weight distribution analysis (number average molecular weight = 222,000 g / mol, weight average molecular weight = 451,000 g / mol, molecular weight distribution = 2.03).

[0053] (S.3) Add the pre-prepared compound branching agent dilution solution (made by mixing 0.9 g methyltrichlorosilane (component A) and 1.21 g triethylamine (component B, A / B molar ratio of 0.5 / 1), diluted with n-hexane to 60 mL, with a component A concentration of 15 g / L) to the reactor. The amount of component A added is 30 mL, accounting for 0.05% of the total monomer mass. Simultaneously with the addition of the branching agent, increase the stirring speed to 140 rpm and continue the reaction at 50°C for 30 minutes. After the reaction is complete, add 15 g of the compound branching agent solution. The reaction was terminated with mL of anhydrous ethanol. After post-treatment, long-chain branched modified rare earth butyl pentylene rubber raw rubber was obtained. Samples were analyzed for Mooney viscosity (49.3), TX80 branching degree (2.9), GPC molecular weight and molecular weight distribution (number average molecular weight = 244,500 g / mol, weight average molecular weight = 496,700 g / mol, molecular weight distribution = 2.05), and cis content (98.3%). After compounding and vulcanization, the compound rubber showed a Mooney viscosity of 60.3 and tensile properties (300% tensile strength = 8.9 MPa, tensile strength...). The following parameters were used to determine the resistance to slippage: tensile strength = 17.8 MPa, elongation at break = 577%, Payne effect analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.233 MPa, wet slip resistance 0℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.438, rolling resistance 50℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.109.

[0054] Example 3 (S.1) 2.2 mmol neodymium isooctanoate, 44 mmol triethylaluminum, 6.6 mmol ethylaluminum chloride, 22 mmol linear polydimethylsiloxane (201-500 methyl silicone oil) and 66 mmol isoprene (as electron donor) were mixed with 150 mL cyclohexane outside the reactor and aged at 20 °C for 60 minutes to obtain the catalyst aging solution.

[0055] (S.2) In a 10L stainless steel polymerization reactor that has been treated to be anhydrous and oxygen-free, 6.0 kg of cyclohexane and 900 g of isoprene monomer (monomer concentration = 13.04% wt.) were added, and the temperature inside the reactor was controlled at 20℃. The catalyst aging solution was injected into the polymerization reactor to initiate polymerization, and the stirring speed was 120 rpm. After the polymerization reaction proceeded for 100 minutes, a sample was taken and the monomer conversion rate was measured to be 99.1%. The isoprene rubber was then precipitated with anhydrous ethanol and dried in a vacuum oven at 60℃ for 24 h to obtain a transparent isoprene rubber block sample. The sample was subjected to Mooney viscosity analysis = 28.5, TX80 branching degree analysis = 1.9, and GPC molecular weight and molecular weight distribution analysis (number average molecular weight = 134,600 g / mol, weight average molecular weight = 273,500 g / mol, molecular weight distribution = 1.84).

[0056] (S.3) At this point, add the pre-prepared compound branching agent dilution. This dilution is prepared by mixing 41.25 g of germanium tetrachloride (component A) and 12.53 g of ethyl tetrahydrofurfuryl ether (component B, A / B molar ratio of 2.0 / 1), and diluting with cyclohexane to 55 mL (component A concentration of 750 g / L). The amount of component A added is 6 mL, accounting for 0.5% of the total monomer mass. While adding the branching agent, increase the stirring speed to 160 rpm and continue the reaction at 20°C for 3 minutes. Subsequently, add 20 mL of 5 wt.% hydrochloric acid aqueous solution to terminate the reaction. After coagulation, washing, and drying, long-chain branched modified rare earth isoprene rubber raw rubber was obtained. Samples were analyzed for Mooney viscosity (67.0), TX80 branching degree (6.4), GPC molecular weight and molecular weight distribution (number-average molecular weight = 443,100 g / mol, weight-average molecular weight = 900,100 g / mol, molecular weight distribution = 2.25), and cis content (98.5%). After compounding and vulcanization, the compound rubber underwent Mooney viscosity analysis (69.3) and tensile property analysis (300% tensile strength = 9.6 MPa, tensile strength...). =18.6MPa, elongation at break =583%), Payne effect analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) =0.213MPa, wet skid resistance 0℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) =0.452, rolling resistance 50℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) =0.104.

[0057] Example 4 (S.1) In a 10L stainless steel polymerization reactor that has been treated to be anhydrous and oxygen-free, add 6.0 kg of n-hexane and 900 g of isoprene monomer (monomer concentration = 13.04% wt.), and control the temperature inside the reactor at 40°C. Add 1.0 mmol of neodymium neodecanoate, 25 mmol of tri-n-butylaluminum, 3.5 mmol of diisobutylaluminum chloride and 20 mmol of linear polydimethylsiloxane (201-200 methyl silicone oil) directly into the polymerization reactor in sequence, and stir at 120 rpm. After 90 minutes of polymerization, the monomer conversion rate reached 97.8%. Isoprene rubber was then precipitated with anhydrous ethanol and dried in a vacuum oven at 60°C for 24 hours to obtain a transparent isoprene rubber block sample. The sample was subjected to Mooney viscosity analysis (45.0), TX80 branching degree analysis (2.5), and GPC molecular weight and molecular weight distribution analysis (number average molecular weight = 212,600 g / mol, weight average molecular weight = 431,800 g / mol, molecular weight distribution = 2.06).

[0058] (S.2) The pre-prepared compound branching agent dilution solution (made by mixing 0.86 g tin tetrachloride (component A) and 0.24 g methyl tert-butyl ether (component B, A / B molar ratio of 1.2 / 1), diluted with n-hexane to 57 mL, with a component A concentration of 15 g / L) was added to the reactor. The amount of component A added was 60 mL, accounting for 0.1% of the total monomer mass. The stirring speed was increased to 155 rpm when adding the branching agent, and the reaction was continued at 40 °C for 10 minutes. After the reaction was completed, 5 g stearic acid and 10 g methyl tert-butyl ether were added. The reaction was terminated with mL of methanol. After post-processing, raw rubber was obtained. Samples were taken for Mooney viscosity analysis (54.2), TX80 branching degree analysis (4.2), GPC molecular weight and molecular weight distribution analysis (number-average molecular weight = 281,600 g / mol, weight-average molecular weight = 572,100 g / mol, molecular weight distribution = 2.11), and cis content analysis (98.6%). After compounding and vulcanization, the compound rubber showed a Mooney viscosity of 63.2 and tensile properties analysis (300% elongation at a constant tensile strength = 9.0 MPa, tensile strength = 18.1 MPa). MPa, elongation at break = 557%), Payne effect analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.213MPa, wet skid resistance 0℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.445, rolling resistance 50℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.104.

[0059] Example 5 (S.1) The pretreatment and feeding operations in the polymerization reactor were the same as in Example 1, with 900 g of isoprene as the monomer and n-hexane as the solvent. The catalyst consisted of 1.2 mmol neodymium neodecanoate, 30 mmol methylaluminoxane, 3.0 mmol diethylaluminum chloride, 6.0 mmol linear polydimethylsiloxane (201-100 methyl silicone oil), and 24 mmol butadiene (as an electron donor) in another container, diluted with n-hexane to a total volume of 200 mL, and aged at 35°C for 20 minutes to obtain the catalyst aging solution. The polymerization was carried out for 85 minutes, and the conversion rate reached 96.5%. Isoprene rubber was then precipitated with anhydrous ethanol and dried in a vacuum oven at 60°C for 24 hours to obtain a transparent isoprene rubber block sample. The sample was subjected to Mooney viscosity analysis (43.0), TX80 branching degree analysis (2.3), and GPC molecular weight and molecular weight distribution analysis (number average molecular weight = 203,100 g / mol, weight average molecular weight = 412,600 g / mol, molecular weight distribution = 2.04).

[0060] (S.2) Add the pre-prepared compound branching agent dilution solution (made by mixing 2.7 g of ethyltin trichloride (component A) and 0.7 g of N-methylpiperidine (component B, A / B molar ratio of 1.5 / 1), diluted with n-hexane to 90 mL, with a component A concentration of 30 g / L). The amount of component A added is 9 mL, accounting for 0.03% of the monomer mass. When adding the branching agent, the stirring speed is increased to 145 rpm, and the reaction is continued at 35°C for 60 minutes. The reaction was terminated with a hexanol solution containing antioxidants. After post-treatment, raw rubber was obtained. Samples were analyzed for Mooney viscosity (45.2), TX80 branching degree (2.7), GPC molecular weight and molecular weight distribution (number-average molecular weight = 219,900 g / mol, weight-average molecular weight = 446,700 g / mol, molecular weight distribution = 2.03), and cis content (98.4%). After compounding and vulcanization, the compound rubber showed a Mooney viscosity of 58.2 and tensile properties (300% elongation at a constant tensile strength = 9.4 MPa, tensile strength = 1 MPa). 7.6 MPa, elongation at break = 553%), Payne effect analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.232 MPa, wet skid resistance 0℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.433, rolling resistance 50℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.113.

[0061] Example 6 (S.1) The pretreatment and feeding operations in the polymerization reactor were the same as in Example 2. The monomer was a mixture of butadiene and isoprene (mass ratio 70 / 30), and the solvent was n-hexane. The catalyst consisted of 2.5 mmol neodymium neodecanoate, 45 mmol triisobutylaluminum, 5.0 mmol isobutylaluminum dichloride, and 50 mmol linear polydimethylsiloxane (201-12500 methyl silicone oil). 50 mmol butadiene was added as an electron donor, and the mixture was aged at 45°C for 25 minutes. The polymerization was carried out for 75 minutes, and the conversion rate reached 95.5%. Isoprene rubber was then precipitated with anhydrous ethanol and dried in a vacuum oven at 60°C for 24 hours to obtain a transparent isoprene rubber block sample. The sample was subjected to Mooney viscosity analysis (23.0), TX80 branching degree analysis (1.5), and GPC molecular weight and molecular weight distribution analysis (number average molecular weight = 108,600 g / mol, weight average molecular weight = 220,700 g / mol, molecular weight distribution = 1.76).

[0062] (S.2) Add the pre-prepared compound branching agent dilution solution (made by mixing 4.5 g tin tetrachloride and 2.90 g diethylene glycol dimethyl ether (component B, A / B molar ratio of 0.8 / 1), diluted with n-hexane to 300 mL, with component A concentration of 15 g / L). The amount of component A added is 12 mL, accounting for 0.2% of the total monomer mass. When adding the branching agent, the stirring speed is increased to 150 rpm, and the reaction is continued at 45°C for 120 minutes. After the reaction was completed, steam was introduced to terminate the reaction. After drying, raw rubber was obtained. Samples were taken for Mooney viscosity analysis (44.3), TX80 branching degree analysis (5.4), GPC molecular weight and molecular weight distribution analysis (number-average molecular weight = 251,100 g / mol, weight-average molecular weight = 510,100 g / mol, molecular weight distribution = 2.18), and cis content analysis (98.3%). After compounding and vulcanization, the compound rubber underwent Mooney viscosity analysis (48.8) and tensile property analysis (300% tensile strength = 8.9 MPa, tensile strength = 1 MPa). 7.8 MPa, elongation at break = 577%), Payne effect analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.212 MPa, wet skid resistance 0℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.447, rolling resistance 50℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.103.

[0063] Comparative Example 1 The main difference between this comparative example and Example 1 is that the branching agent is not in a compound form, but only component A is used.

[0064] Under the same polymerization conditions, catalyst system (including anti-foaming agent), and reaction timing as in Example 1, the branching reaction step was modified as follows: 7.84 g of tin tetrachloride (component A, the same amount as component A in Example 1) was added to the rubber solution and diluted to 100 mL with n-hexane, without adding any tetrahydrofuran (component B). The stirring speed was increased to 150 rpm during addition, and the reaction was terminated after 15 minutes. Samples were taken for Mooney viscosity analysis (55.3), TX80 branching degree analysis (6.7), GPC molecular weight and molecular weight distribution analysis (number average molecular weight = 202,100 g / mol, weight average molecular weight = 623,100 g / mol, molecular weight distribution = 3.08), and cis content analysis (98.1%). After compounding and vulcanization, the compound rubber underwent Mooney viscosity analysis (66.7) and tensile property analysis (300% elongation at break = 8.0 MPa, tensile strength = 14.8 MPa, elongation at break = 100 MPa). =407%), Payne effect analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.362MPa, wet slip resistance 0℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.442, rolling resistance 50℃ tanδ analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.143. The obtained raw rubber gel content was significantly higher than that of the sample in Example 1, and a sudden increase in local viscosity of the glue was observed during the addition of the branching agent, indicating obvious uneven dispersion. Trace gel particles were visible in the glue block obtained after subsequent coagulation and drying. Gel content analysis = 0.56%, viscosity analysis of 5% toluene solution at 25℃ = 664cps.

[0065] Comparative Example 2 The main difference between this comparative example and Example 1 is that the amount of component B in the compound branching agent is too high.

[0066] The operation process is the same as in Example 1, but the preparation of the compound branching agent is changed: 7.84 g of tin tetrachloride (component A) and 7.90 g of tetrahydrofuran (component B, A / B molar ratio of 0.5 / 1) are mixed and diluted with n-hexane to 100 mL. After the branching reaction, samples are taken for Mooney viscosity analysis = 54.6, TX80 branching degree analysis = 4.7, GPC molecular weight and molecular weight distribution analysis (number average molecular weight = 283,500 g / mol, weight average molecular weight = 615,200 g / mol, molecular weight distribution = 2.17), and cis content analysis = 98.6%; after compounding and vulcanization, the compound rubber is subjected to Mooney viscosity analysis = 61.3, tensile property analysis (300% tensile strength = 9.5 MPa, tensile strength = 18.6 MPa, elongation at break = 567%), and Payne effect analysis Δ. E'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.212 MPa, anti-slip property tanδ analysis at 0℃ ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.441, rolling resistance tanδ analysis at 50℃ ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.102, gel content analysis = 0.14%, 5% toluene solution viscosity analysis at 25℃ = 364 cps. This indicates that excessive component B has little impact on the branching reaction process. Its main function is to passivate the active centers to avoid additional consumption of branching agent component A, while also better compatibilizing branching agent component A. However, excessive addition of component B is detrimental to solvent system recovery and purification, potentially affecting subsequent polymerization reactions, and also carries the risk of increasing raw material costs.

[0067] Comparative Example 3 The main difference between this comparative example and Example 1 is that the catalyst does not contain a coagulant inhibitor (linear polydimethylsiloxane).

[0068] The polymerization catalyst consisted only of 1.5 mmol neodymium neodecanoate, 30 mmol triisobutylaluminum, 4.5 mmol diethylaluminum chloride, and 30 mmol butadiene (electron donor), without any coagulant inhibitor. All other conditions, parameters, and the compounded branching agent used (A / B molar ratio 1.0 / 1) for the polymerization and branching reactions were identical to those in Example 1. After the reaction, a large amount of viscous, gelatinous material was observed adhering to the reactor walls and agitator blades upon opening the reactor, making cleaning difficult. The yield of effective rubber was significantly lower than that in Example 1, and due to uneven mass transfer within the reactor, the Mooney viscosity fluctuation range (within-batch sampling tests) of the final raw rubber was wider than that of the product in Example 1. Sampling was subjected to Mooney viscosity analysis (56.2), TX80 branching analysis (5.7), GPC molecular weight and molecular weight distribution analysis (number average molecular weight = 210,800 g / mol, weight average molecular weight = 674,600 g / mol, molecular weight distribution = 3.20), and cis content analysis (98.0%). After mixing and vulcanization, the mixed rubber underwent Mooney viscosity analysis (71.66), tensile property analysis (300% tensile strength = 7.5 MPa, tensile strength = 13.6 MPa, elongation at break = 367%), and Payne effect analysis (ΔE'). =0.410MPa (50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.465, tanδ analysis of wet skid resistance at 0℃ = 0.151, gel content analysis = 0.62%, viscosity analysis of 5% toluene solution at 25℃ = 764cps.

[0069] Comparative Example 4 The main difference between this comparative example and Example 1 is that it uses disulfur dichloride (S2Cl2), a traditional highly active branching agent mentioned in the background art.

[0070] The polymerization and catalyst system (including the anti-gelling agent) were the same as in Example 1. When the polymerization conversion reached 98.5%, the compounded branching agent was not added; instead, a hexane solution containing disulfur dichloride (calculated as sulfur atoms) in an equivalent molar amount as in Example 1 was added. After addition, the solution rapidly thickened and developed a pungent odor, and the reaction system temperature locally increased. The reaction was terminated after 15 minutes. The resulting product had a high gel content, making it impossible to dissolve smoothly using conventional methods for accurate GPC molecular weight testing. The raw rubber showed obvious insoluble micelles and poor processing performance. Mooney viscosity analysis was 76.2, TX80 branching degree analysis was 13.7, GPC molecular weight and molecular weight distribution analysis could not be performed smoothly (the sample could not be completely dissolved), and cis content analysis was 97.2%. There was clearly too much gel, making compounding and vulcanization ineffective, and subsequent tensile property and DMA analysis could not be carried out. The gel content analysis was 2.38%, and viscosity analysis of a 5% toluene solution at 25°C could not be performed smoothly (the sample could not be completely dissolved).

[0071] Comparative Example 5 The main difference between this comparative example and Example 1 is that the branching agent was added too early, at the beginning of the polymerization reaction.

[0072] Ten minutes after the start of the polymerization reaction in Example 1 (at which point the monomer conversion rate was approximately 30%), a diluted solution of the same compound branching agent (A / B molar ratio 1.0 / 1) as in Example 1 was added, in the same amount. The reaction was continued for a total time of 95 minutes (the total polymerization + branching time was comparable to that of Example 1) before termination. The resulting rubber had a lower content of cis-1,4 structure than the product of Example 1, and its molecular weight distribution was significantly wider. The improvement in the cold flow properties of the raw rubber was much smaller than that in Example 1, indicating that premature branching interfered with the regular growth of the polymer backbone, failing to form the ideal long-chain branched topology. Samples were subjected to Mooney viscosity analysis (26.2), TX80 branching degree analysis (3.7), GPC molecular weight and molecular weight distribution analysis (number average molecular weight = 110,800 g / mol, weight average molecular weight = 295,800 g / mol, molecular weight distribution = 2.67), and cis content analysis (98.5%). After mixing and vulcanization, the Mooney viscosity of the compound was 30.66, and the conversion rate was ≤60%. Subsequent tensile property analysis and DMA analysis were not carried out.

[0073] Comparative Example 6 The main difference between this comparative example and Example 1 is that no branching agent is added.

[0074] (S.1) 0.45 mmol neodymium neodecanoate, 9 mmol triisobutylaluminum, 1.35 mmol diethylaluminum chloride, 4.5 mmol linear polydimethylsiloxane (201-350 methyl silicone oil) and 9 mmol butadiene (as electron donor) were diluted with n-hexane to a total volume of 100 mL in another container and aged at 25 °C for 30 minutes to obtain the catalyst aging solution.

[0075] (S.2) In a 10L stainless steel polymerization reactor that has been treated to be anhydrous and oxygen-free, 6.0 kg of n-hexane that has been deeply dehydrated by molecular sieve and 900 g of isoprene monomer (monomer concentration 13.04% wt.) were added, and the reactor temperature was controlled at 30°C. The catalyst aging solution was injected into the polymerization reactor to initiate the polymerization reaction, and the stirring speed was 120 rpm. After the polymerization reaction proceeded for 80 minutes, a sample was taken and the monomer conversion rate was measured to be 98.5%. Subsequently, 10 mL of n-hexane solution containing 2 wt.% cyclohexanol was added to the reactor to terminate the reaction. After coagulation and drying, linear rare earth isoprene rubber raw rubber was obtained. Samples were analyzed for Mooney viscosity (53.0), TX80 branching degree (2.2), GPC molecular weight and molecular weight distribution (number-average molecular weight = 283,500 g / mol, weight-average molecular weight = 519,000 g / mol, molecular weight distribution = 1.83), and cis content (98.7%). After compounding and vulcanization, the compound rubber showed a Mooney viscosity of 69.6 and tensile properties (300% tensile strength = 9.6 MPa, tensile strength = 17.2 MPa, elongation at break = 527%). Payne effect analysis ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.308MPa; wet skid resistance tanδ analysis at 0℃ ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.457; rolling resistance tanδ analysis at 50℃ ΔE'(50℃; 10Hz; 0.1%-10% strain / 10μm / min step) = 0.133; gel content analysis = 0.12%; viscosity analysis of 5% toluene solution at 25℃ = 632cps.

[0076] Through system testing and comparison of the embodiments and comparative examples, the following conclusions can be drawn: This invention indeed achieves efficient and controllable long-chain branching modification: all examples (1-6) successfully prepared raw gum. Its Mooney viscosity was moderately and controllably increased, the gel content was effectively controlled at extremely low levels, and the relative viscosity of the 5% toluene solution also decreased significantly. This proves that the technical solution of this invention, "compound branching agent (A+B) combined with a specific process," can simultaneously achieve the comprehensive goals of improving processing performance, reducing gum viscosity, and strictly suppressing gelation side reactions.

[0077] Comparative Example 1 (component A only) produced undesirable products with high gelation and high solution viscosity, demonstrating that without component B to improve dispersion, component A itself cannot achieve uniform and controllable branching. Comparative Example 2 shows that excessive component B has little impact on the branching reaction process; its main function is to passivate the active centers to avoid additional consumption of branching agent component A, while also better compatibilizing component A. However, excessive addition of component B is detrimental to solvent system recovery and purification, potentially affecting subsequent polymerization reactions, and also carries the risk of increasing raw material costs. Comparative Example 4 (traditional branching agent S2Cl2) resulted in complete gelation of the product, rendering it unusable, strongly highlighting the significant advantage of this invention in reaction controllability. The final rubber performance data of Comparative Example 3 (without a gel inhibitor) was not significantly different from that of Example 1, but serious equipment glue buildup occurred during production, leading to decreased yield and production discontinuity. This demonstrates that although gel inhibitors do not directly affect the core physical properties of the final product, they are indispensable for ensuring continuous, stable, and efficient industrial production, enhancing the practical value of this technical solution. In Comparative Example 5, premature addition of the branching agent inhibited the polymerization reaction too early, broadened the molecular weight distribution, prevented Mooney density from being achieved, and severely degraded product performance. In Comparative Example 6, the absence of any branching agent resulted in a significant increase in solution viscosity and increased processing difficulty, indicating that long-chain branching modification is beneficial for improving product transport and processing difficulty, and also significantly improves the product's dynamic properties.

[0078] In summary, the test data fully validates the effectiveness, synergy, and inventiveness of the technical solution of this invention. It successfully solves the problems of difficult gel control, uneven reaction, numerous side reactions, high cost, or complex processes existing in the background technology, and provides a reliable path for the efficient and controllable preparation of high-performance long-chain branched rare earth rubber in industrial settings.

Claims

1. A method for long-chain branching modification of rare earth isoprene rubber and / or butyl pentadiene rubber, characterized in that, Includes the following steps: S1. In the presence of a rare earth catalyst, isoprene and / or butadiene are subjected to solution polymerization in a nonpolar solvent to obtain a gel containing active polymer molecular chains. S2. When the polymerization conversion rate reaches 95% or more, a compound branching agent is added to the adhesive to carry out a branching reaction; The compound branching agent comprises component A and component B; Component A is selected from at least one of chlorides and alkyl halides; Component B is selected from at least one of ether compounds and tertiary amine compounds; The molar ratio of component B to component A is 0.5:1 to 2.0:

1.

2. The long-chain branching modification method according to claim 1, characterized in that, Component A is selected from at least one of silicon tetrachloride, methyl silicon trichloride, ethyl silicon trichloride, n-propyl silicon trichloride, isopropyl silicon trichloride, n-butyl silicon trichloride, isobutyl silicon trichloride, tert-butyl silicon trichloride, sec-butyl silicon trichloride, octyl silicon trichloride, germanium tetrachloride, methyl germanium trichloride, ethyl germanium trichloride, n-propyl germanium trichloride, isopropyl germanium trichloride, n-butyl germanium trichloride, isobutyl germanium trichloride, tert-butyl germanium trichloride, sec-butyl germanium trichloride, octyl germanium trichloride, tin tetrachloride, methyl tin trichloride, ethyl tin trichloride, n-propyl tin trichloride, isopropyl tin trichloride, n-butyl tin trichloride, isobutyl tin trichloride, tert-butyl tin trichloride, sec-butyl tin trichloride, and octyl tin trichloride.

3. The long-chain branching modification method according to claim 1 or 2, characterized in that, The ether compounds in component B include at least one of the following: diethyl ether, dimethyl ether, methyl ethyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, ethyl tetrahydrofurfuryl ether, N,N-dimethyltetrahydrofurfurylamine, 2,2-bis(2-tetrahydrofuranyl)propane, anisole, ethylene oxide, and propylene oxide. The tertiary amines include at least one of triethylamine, hexamethylenediamine, N-methylpiperidine, N-ethylpiperidine, N-methylcyclohexylimine, N-ethylcyclohexylimine, N,N-bis(3-dimethylaminopropyl)methylamine, and tri(3-dimethylaminopropyl)amine.

4. The long-chain branching modification method according to claim 1, characterized in that, The molar ratio of component B to component A is 0.8:1 to 1.5:

1.

5. The long-chain branching modification method according to claim 4, characterized in that, The molar ratio of component B to component A is 0.95:1 to 1.05:

1.

6. The long-chain branching modification method according to claim 1, characterized in that, In step S1, the rare earth catalyst comprises the following components: (i) Neodymium organic acids; (ii) Alkyl aluminum compounds; (iii) Halogenated compounds; (iv) An optional electron donor; (v) A coagulant inhibitor, wherein the coagulant inhibitor is a siloxane compound.

7. The long-chain branching modification method according to claim 6, characterized in that, The molar ratio of the anticoagulant to the neodymium element in the organic acid neodymium compound is from 0.01:1 to 100:

1.

8. The long-chain branching modification method according to claim 1, characterized in that, The branching reaction takes between 1 minute and 120 minutes.

9. The long-chain branching modification method according to claim 1, characterized in that, The compound branching agent is added in the form of a diluent, wherein the concentration of component A in the diluent is from 15 g / L to 750 g / L, and the amount of component A added is from 0.01 wt.% to 0.50 wt.% based on the total mass of the monomers.

10. The long-chain branching modification method according to claim 1, characterized in that, Before adding the adhesive, component A and component B are mixed under an inert atmosphere and then diluted with the non-polar solvent to form a diluted solution of the compound branching agent.

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