A conjugated diene rubber having branched, broad distribution, high content of side vinyl groups, and a method of making and use thereof

Abstract

The application discloses conjugated diene rubber with branching, wide distribution and high content of side vinyl groups and a preparation method and application thereof. The conjugated diene rubber has the following structural expression: wherein the conjugated diene block is represented by, the total mass fraction of 1,2-addition units and 3,4-addition units in the conjugated diene block accounts for 65-83%, D is a branching node, the conjugated diene rubber has the characteristics of wide molecular weight distribution, high stiffness, large melt elasticity, good processing performance and high content of side vinyl groups, can be widely applied to tire rubber, has low tire rolling resistance, excellent wet skid resistance and low heat build-up performance. The conjugated diene rubber is obtained through anionic polymerization, has the characteristics of fast polymerization speed, high monomer conversion rate, simple operation, low cost and easy industrial production, etc.

Description

Technical Field

[0001] This invention relates to a conjugated diene rubber, specifically a conjugated diene rubber with branching, broad distribution, and high side alkenyl content, and also relates to its preparation method and its application as a base rubber for shoe soles, tire sidewall rubbers, or tire treads, belonging to the field of functional rubber synthesis technology. Background Technology

[0002] Generally, conjugated diene rubbers with a side alkenyl content greater than 65% are called high side alkenyl rubbers, while those with a side alkenyl content of 65% or more and 30% or more are called medium side alkenyl rubbers.

[0003] Traditional Ziegler-Natta catalysts, such as nickel-based, rare-earth-based, cobalt-based, and titanium-based catalysts, synthesize conjugated diene rubbers, specifically butadiene rubber (BR) and polyisoprene rubber (IR). These rubbers are characterized by high cis 1,4-additive molecules. For example, commercially available rubbers such as BR-9000, CB-24, and IR2200 contain no more than 5% 1,2-additive units (side vinyl groups) or 3,4-additive units (side isopropylene groups) in their molecular chains. These rubbers are mainly used in tire sidewalls; if used as tread rubbers, their wet grip performance is poor.

[0004] In the 1980s, the Soviet Union successfully synthesized highly branched conjugated diene rubber (iron-based rubber) with high side-alkene content from butadiene or isoprene using iron-based catalysts. Since 2020, the Qingdao Institute of Energy Chemistry of the Chinese Academy of Sciences and Sinopec Baling Petrochemical Company have also been conducting research on preparing highly branched butadiene-pentadiene rubber with high side-alkene content by copolymerizing butadiene and / or isoprene with iron-based catalysts and toluene as a solvent. However, this method has drawbacks such as long polymerization time, high gel content leading to poor physical properties, severe glue buildup in the polymerization reactor leading to reactor burnout, incomplete monomer conversion, poor self-adhesion of raw rubber, poor processing performance, difficulty in removing the solvent toluene, and the presence of excessive metallic iron in the raw rubber which accelerates the catalytic oxidation of the vulcanized rubber and makes it difficult to industrialize.

[0005] In 2017, Qingdao University of Science and Technology and Sinopec Baling Petrochemical Company synthesized a high-ethylene-content BR (Mo-HVPB) using a molybdenum-based method. This molybdenum-based catalyst system consists of a molybdenum agent, an aluminum agent, and a co-catalyst: the molybdenum agent is prepared by reacting MoCl5 with a phosphorus-containing compound to produce a phosphorus-containing ligand; the aluminum agent is prepared by reacting triisobutylaluminum with a phenolic compound; and the co-catalyst is a structural modifier used to adjust the degree of molecular chain branching and molecular weight distribution. Mo-HVPB, used as a tire tread compound, exhibits good processing rheology and low heat generation. Compared to commercially available products such as BR9000, ESBR1502, and SSBR2305, Mo-HVPB possesses superior wet skid resistance and low heat generation. For example, Chinese patent (CN1884328A) discloses a method for preparing branched high-vinyl polybutadiene rubber using molybdenum-based catalysis. This method involves the coordination polymerization of butadiene using Mo-based catalysis to prepare structurally controllable branched high-vinyl polybutadiene rubber. The prepared polymer has suitable molecular weight and distribution, with a vinyl content exceeding 80%. The properties, length, distribution, and degree of branching of the branches are controllable and adjustable within a certain range, resulting in excellent processing performance and physical and mechanical properties. Another example is Chinese patent (CN105199028A), which discloses a microstructure-adjustable high-vinyl polybutadiene rubber and its preparation method. This method uses an alkyl alcohol-substituted MOCl5 as the main catalyst and alkylaluminum as the co-catalyst. By adjusting the catalyst ratio and polymerization temperature, the polymerization behavior and product microstructure can be controlled. This new synthetic method prepares polybutadiene with a wide adjustable vinyl content ranging from 60% to 90%. The product can be used to prepare new materials with excellent comprehensive properties such as low rolling resistance, low heat generation, high anti-slip properties, and high wear resistance. Meanwhile, Chinese patent (CN106317281B) discloses a method for preparing heat-stable high-vinyl butadiene rubber. Specifically, under nitrogen protection, a hexane polymerization solution of butadiene monomer is added to an anhydrous and oxygen-free polymerization tank, followed by the sequential addition of an oxygen-containing ligand Mo-based main catalyst and an alkyl aluminum co-catalyst. The molar ratio of the oxygen-containing ligand Mo-based main catalyst to the butadiene monomer is (0.2~10)×10. -4 The molar ratio of alkylaluminum co-catalyst to oxygen-containing ligand Mo-based main catalyst is (5-40):1. The polymerization reaction is carried out at 30℃-80℃ for 10 hours, and the 1,2 structure content of the prepared polybutadiene is above 80%. The above three technologies all belong to Ziegler-Natta modified coordination polymerization, but they have low catalytic activity, long polymerization reaction time, butadiene monomer conversion rate <85%, and the viscosity and gelation of the raw rubber are not easy to control. The rubber in the polymerization reactor is seriously coated, and the physical properties of the vulcanized rubber are greatly damaged.

[0006] The paper "Synthesis and Performance Characterization of Titanium-Based Isoprene Rubber" (Zhang Jianguo et al., *Synthetic Rubber Industry*, 2011-09-15) describes the synthesis of IR with a 1,4-addition unit content >97% using isoprene as a monomer and toluene as a solvent, with triisobutylaluminum-titanium tetrachloride as a catalyst. This IR requires removal of catalyst residues, and the monomer conversion rate is less than 83%. The synthesized raw rubber can partially replace natural rubber. Chinese patent (publication number CN102911298A) discloses a catalytic system for isoprene polymerization and its preparation method, specifically introducing the preparation of polyisoprene rubber or rare earth polybutadiene rubber using a neodymium neodecanoate-triisobutylaluminum-diethylaluminum chloride catalytic system. The prepared BR molecule has a cis-1,4 content of 98% and no other functional groups in its molecular structure. This rubber, when combined with general-purpose SSBR, can only be used in the manufacture of B / C grade tires.

[0007] The paper "Research on Dynamic Mechanical Properties and Thermal Conductivity of ESBR Composites for High-Performance Tire Tread Rubber" (Shanghai Jiao Tong University, Materials Science, 2012) mentions the urgent need for "green tires" with high wear resistance, high wet skid resistance, low heat generation, and low rolling resistance in modern society. While emulsion-polymerized styrene-butadiene rubber (ESBR) exhibits good wear resistance and wet skid resistance when used in tire treads, its molecular chain structure limits its heat generation, and its thermal conductivity is relatively low. Traditional ESBR composites do not meet the requirements for "green tires." Both US4424323A and US4451576A describe anionic polymerization using butyllithium as an initiator, with hindered amine compounds regulating the reaction rate of the conjugated diene monomers, and adjusting the polymer molecular weight distribution index M... W / Mn≥2.0, but this synthesis method has defects such as monomer conversion rate of less than 90%, excessive amount of hindered amine, loss of activity of active lithium, low stiffness of raw rubber and large cold flow.

[0008] A method for preparing high-vinyl polybutadiene oil-extended rubber and its preparation was disclosed in "High-Vinyl Polybutadiene Oil-Extended Rubber and Its Preparation Method," Rubber Technology, April 2013. This product is obtained by a wet process where branched high-vinyl polybutadiene rubber slurry is oil-extended, stirred for 2-4 hours, and then coagulated and dried. Another example is "Molecular Design of Star-Shaped Vinyl Polybutadiene Rubber," Proceedings of the 2004 International Rubber Conference (A), which describes the preparation of energy-saving polybutadiene rubber with low rolling resistance and high wet skid resistance. By analyzing the relationship between polymer properties and structure, the molecular structure of star-shaped vinyl polybutadiene rubber was designed using polymer molecular design, including the molecular chain ends, number of molecular arms, vinyl content, relative molecular mass of each arm, and relative molecular mass distribution. Using tin-coupled multifunctional organolithium as an initiator and tetrahydrofuran as a microstructure modifier, star-shaped vinyl polybutadiene rubber (S-MVBR) was synthesized in a one-step process in raffinate oil. The influencing factors on the molecular structure and the corresponding control methods were analyzed. For example, the BR prepared by anionic polymerization with hindered amine as a modifier has a butadiene conversion rate of no more than 81%, a vinyl content of 43-50%, and a molecular weight distribution of 1.1-7.15. Although the raw rubber exhibits excellent processing performance, the raw rubber molecules have high linearity, large cold flow, and low melt elasticity.

[0009] In summary, conjugated diene rubber with high side-alkene content has become a popular brand, but commercial production has not yet been achieved in China in recent years. The root causes are nothing more than low monomer catalytic activity, long polymerization reaction time, low monomer conversion rate, unstable raw rubber quality, and low tensile strength of vulcanized rubber. However, no relevant technologies have yet been reported for preparing high-side-alkene polyconjugated diene rubber with high monomer conversion rate, highly branched molecular chains, high weight-average molecular weight, wide molecular weight distribution, good stiffness, high melt elasticity, and good processing performance using anionic polymerization. Summary of the Invention

[0010] To address the shortcomings of existing technologies for synthesizing highly branched, broadly distributed polybutadiene rubber, polyisoprene rubber, or butadiene-pentadiene rubber via iron-based and molybdenum-based catalysis, such as long polymerization time, high gel content, low monomer conversion, poor self-adhesion of raw rubber, poor processing performance, difficulty in solvent removal, and difficulty in removing excessive metal catalyst residues, as well as the shortcomings of existing anionicly polymerized conjugated diene rubbers, such as narrow molecular weight distribution leading to poor processing performance and the use of hindered amines as regulators resulting in slow monomer polymerization rate and low monomer conversion rate.

[0011] The first objective of this invention is to provide a conjugated diene rubber with asymmetric long-chain branching, wide molecular weight distribution, and high content of side-chain alkenyl units. This conjugated diene rubber has advantages such as high stiffness, no gelation, low cold flow, good processability, excellent physical and mechanical properties, excellent wet skid resistance, and low rolling resistance, making it an ideal rubber material for high-performance tire treads, sidewalls, or shoe soles.

[0012] Another objective of this invention is to provide a method for preparing conjugated diene rubber with branching, wide distribution, and high side alkenyl content. This method is achieved through anionic polymerization and has the advantages of fast polymerization speed, high monomer conversion rate, simple operation, low cost, and ease of industrial production, making it suitable for widespread application.

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] To achieve the above technical objectives, the present invention provides a conjugated diene rubber (HVDR) with branching, broad distribution, and high side alkenyl content, which has the following structural expression:

[0015]

[0016] in,

[0017] It is a conjugated diene block, and the total mass fraction of 1,2-addition units and 3,4-addition units in the conjugated diene block is 65% to 83%; D is a branching node.

[0018] The HVDR structure of this invention contains conjugated diene blocks that simultaneously include 1,4-addition units, 1,2-addition units, and / or 3,4-addition units of conjugated dienes. These conjugated diene addition units are randomly distributed, especially the proportion of conjugated dienes with 1,2-addition units and 3,4-addition units, which is as high as 65% to 83%. The content of side vinyl groups affects the vulcanization effect of the rubber. If the content of side alkenyl groups is too low, the wet skid resistance of the vulcanizate is poor and the vulcanizate does not meet the Grade A standard. If the content of side alkenyl groups is too high, the glass transition temperature of the rubber increases accordingly, and the vulcanizate exhibits defects such as poor low-temperature performance and abrasion resistance, low strength, high heat generation, and other poor overall performance. In the HVDR structural formula, D is the branching node. The conjugated diene blocks are connected through the branching nodes to form random straight chains and / or asymmetric branched long chain structures, which improves the molecular weight distribution. Its wide molecular weight distribution and the appropriate branching of the molecular chains to form asymmetric long chain structures endow the rubber melt with good elasticity and stiffness, and improve its processing performance.

[0019] As a preferred embodiment, the conjugated diene block is composed of at least one conjugated diene unit selected from butadiene, isoprene, and isoprene. More preferably, the conjugated diene block is composed of butadiene and / or isoprene conjugated diene units. Most preferably, the conjugated diene block is composed of butadiene and isoprene units in a mass percentage ratio of 5–95%:95–5%. The presence of isoprene units in the conjugated diene block can increase the anti-slip properties of the polymer vulcanizate, thanks to the presence of isoprene units in the polymer molecular chain. However, the content of the isopropylene side branch should not be too high, otherwise the Tg will also increase. Therefore, considering all factors, random units with high and suitable side molecular chains of vinyl and isopropylene groups best meet the overall performance requirements of rubber engineering and practical applications.

[0020] As a preferred embodiment, the branching node is a divinylbenzene unit.

[0021] As a preferred embodiment, the branched nodes account for 0.03–0.10% of the total mass of the conjugated diene blocks. A further preferred embodiment is that the branched nodes account for 0.05–0.08% of the total mass of the conjugated diene blocks. If there are too many branched nodes, the higher the degree of branching, the greater the polymer viscosity and the larger the molecular weight (MW), resulting in poorer flowability of the polymer solution and potentially leading to gelation. Conversely, if the number of branched nodes is too low, the amount of divinylbenzene units is small, resulting in low branching and polymer shift towards linear molecules, leading to a decrease in MW. W The molecular weight distribution of raw rubber decreases, which prevents the widening of the molecular weight distribution and results in poor processing performance.

[0022] As a preferred option, the molecular weight distribution index M w / M n =1.9~2.5, Mooney viscosity ML(1+4 =45~55.

[0023] The present invention also provides a method for preparing a conjugated diene rubber with branching, wide distribution and high side alkenyl content. The method involves simultaneously and uniformly adding an initiator and a conjugated diene monomer to a solution system containing a structure modifier to carry out a polymerization reaction. After the conjugated diene monomer is added, a divinylbenzene monomer is added to continue the polymerization reaction. After the polymerization reaction is completed, the product is obtained.

[0024] In the HVDR synthesis process of this invention, the addition of the divinylbenzene monomer must be carried out after the addition of the conjugated diene monomer in the solution system for polymerization. This is mainly because divinylbenzene has high reactivity and its polymerization rate is much higher than that of the conjugated diene. If it is added together with the conjugated diene monomer, gel formation is likely to occur. However, adding the divinylbenzene monomer after the conjugated diene monomer has been added for a period of time allows the polymer to grow while the divinylbenzene randomly forms asymmetric long-chain branched chains or branched nodes, effectively avoiding the formation of gels from the homopolymerization of divinylbenzene.

[0025] As a preferred embodiment, the initiator is an alkyl lithium. Alkyl lithium, for example, is butyl lithium; more specifically, n-butyl lithium can be selected.

[0026] As a preferred embodiment, the structure modifier is tetrahydrofurfuryl ethyl ether and / or tetrahydrofurfuryl hexyl ether. As a more preferred embodiment, the fraction of the structure modifier in the solution system is 0.03–0.06%. By selecting tetrahydrofurfuryl ethyl ether and / or tetrahydrofurfuryl hexyl ether, which have strong structure-modifying capabilities, as structure modifiers for conjugated diene polymerization, and by controlling the amount of structure modifier, the total mass percentage content of 1,2-addition units and 3,4-addition units in the front end of the conjugated diene polymerization can be effectively controlled within the range of 65%–83%. Preferably, tetrahydrofurfuryl ethyl ether and / or tetrahydrofurfuryl hexyl ether are multifunctional Lewis bases with low temperature sensitivity; using them as structure modifiers can effectively regulate the structure of the conjugated diene under low-temperature conditions.

[0027] As a preferred embodiment, the solution system uses hexane and / or cyclohexane as solvents, and the amount of solvent used ensures that the mass fraction of the polymerizable monomer in the solvent is 7-15%.

[0028] As a preferred embodiment, the initiator and conjugated diene monomer are added to the solution system containing the structure modifier within 40 to 60 minutes.

[0029] As a preferred embodiment, during the polymerization reaction, the pressure is controlled at 3–4.5 bar, the initial polymerization temperature is controlled within the range of 50–55°C, and the maximum polymerization temperature is controlled below 68°C. In the synthesis of HVDR, the polymerization initiation temperature is not lower than 50°C, and as the monomer polymerization is exothermic, the maximum polymerization temperature does not exceed 68°C. Existing Lewis bases (anionic polymerization structure modifiers) do not have high modulating ability at temperatures above 70°C, even at concentrations as high as 600 mg / kg, resulting in a side alkenyl content of less than 65%. However, the structure modifier selected in this invention easily controls the side alkenyl content to reach over 65% under conditions of lower polymerization temperature and lower dosage.

[0030] The present invention achieves a high conversion rate of conjugated diene monomers, >99%, during the anionic polymerization synthesis of HVDR.

[0031] The preferred preparation method of HVDR provided by the present invention is as follows: A certain amount of hexane or cyclohexane solvent is added to a clean steel polymerization reactor, along with a certain amount of structure modifier. The reactor liquid is then heated to 50-55°C. Within 40-45 minutes, conjugated diene monomer and NBL are continuously and uniformly added to the polymerization reactor. After the monomer is added, divinylbenzene is added, and the reaction continues for another 30 minutes. During this period, if necessary, cooling water is introduced to remove the heat of reaction and maintain the polymerization temperature not higher than 68°C. Finally, the gel is discharged and a small amount of water is added to terminate the reaction. A certain amount of antioxidant is then added and mixed evenly. The gel is then coagulated, dehydrated, and dried to obtain transparent block HVDR raw rubber.

[0032] The antioxidants used in this invention can be phenolic and amine antioxidants known to those skilled in the art, such as antioxidant 1076, etc., and their addition amount relative to the amount of conjugated diene monomer is 0.25-0.35g / 100g.

[0033] The present invention also provides an application of a conjugated diene rubber with branching, wide distribution, and high side alkenyl content, which is used as a base rubber for shoe soles, tire sidewall rubbers, or tire tread rubbers.

[0034] The common HVDR vulcanizate formulation (parts by weight) of the present invention is as follows: HVDR raw rubber, 100 parts; stearic acid, 2.5 parts; zinc oxide, 5 parts; TDAE rubber oil, 15 parts; accelerator TBBS, 1.5 parts; sulfur, 1.8 parts; N330, 50 parts.

[0035] The HVDR raw rubber provided by this invention is processed and vulcanized in the same way as existing general-purpose conjugated diene rubbers.

[0036] The HVDR provided by this invention is mainly used in the sidewall and tread of radial tires. It is also an ideal compound for solution styrene-butadiene rubber (SSBR). The resulting tires have low heat generation, and the prepared tread compound has extremely high wet skid resistance and low rolling resistance.

[0037] Compared with existing technologies, the beneficial effects of the technical solution of this invention are as follows:

[0038] Existing high-cis-butadiene rubbers suffer from several drawbacks: monomer conversion rates are no higher than 85%, and cis-1,4-structure content is as high as 95%, resulting in poor wet skid resistance when used as tire tread rubbers. Furthermore, existing lithium-based BRs exhibit narrow molecular weight distribution and poor processing performance. Existing iron- and molybdenum-based synthesized highly branched, broadly distributed polybutadiene rubbers, polyisoprene rubbers, or terephthalic rubbers suffer from long polymerization times, high gel content, low monomer conversion, poor self-adhesion of raw rubber, poor processing performance, difficulty in solvent removal, and difficulty in removing excessive metal catalyst residues. Additionally, existing anionicly polymerized conjugated diene rubbers suffer from narrow molecular weight distribution leading to poor processing performance, and the use of hindered amines as regulators results in slow monomer polymerization rates and low monomer conversion rates.

[0039] The HVDR preparation process provided by this invention features fast monomer polymerization rate, complete conversion, and easy control.

[0040] The HVDR raw rubber provided by this invention also has a wide molecular weight distribution, adjustable molecular chain branching, good melt elasticity and stiffness, and good processing performance. It is an ideal rubber type for radial tire treads. The vulcanized rubber has excellent physical properties and a long service life. It also has low heat generation, especially excellent wet skid resistance, while maintaining the original low rolling resistance. It is one of the excellent materials for high-performance green tires.

[0041] The HVDR preparation process provided by this invention is a homogeneous reaction, simple to prepare, can be synthesized using existing mature processes, the reaction is easy to control, and it is easy to industrialize. Attached Figure Description

[0042] Figure 1 The GPC chromatogram of HVDR-1# raw gum is shown.

[0043] Figure 2 HVDR-1# raw rubber 1 -NMR spectrum; Figure 2 Chemical shifts 4.6–4.7 represent hydrogen protons on the 3,4-addition units of the isoprene chain, chemical shifts 4.9–4.95 represent hydrogen protons on the side vinyl groups of the butadiene polymerization, chemical shift 5.13 represents hydrogen protons on the 1,4-addition units of isoprene, and chemical shifts 5.3–5.4 represent hydrogen protons on the 1,4-hydrogen proton-addition units of butadiene. Detailed Implementation

[0044] The following specific embodiments are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims.

[0045] In the following examples, the molecular weight distribution index of the polymer was determined using gel permeation chromatography (GPC); H2 was used. 1 - The microstructure of the polymer was quantitatively determined by NMR spectroscopy; the mechanical properties of the vulcanizate were tested according to GB / T36089-2018; the tanδ value at 0℃ was measured by dynamic viscoelastic spectrometry to characterize the wet skid resistance of the vulcanizate, and the tanδ value at 60℃ was used to characterize the rolling resistance of the tire tread compound; the dynamic heat generation of the vulcanizate was measured by DUNLOP power loss meter.

[0046] Example 1

[0047] Under nitrogen protection, 3500 mL of cyclohexane solution and 0.85 mL of tetrahydrofurfuryl ethyl ether were added to a 5L polymerization reactor. Stirring was started and the material temperature was raised to 50°C. Simultaneously, 3.3 mL of 0.78 mol / L NBL and 350 mL of butadiene were added to the reactor over 45 min. After the monomers were added, 1.8 mL of a 10.4% divinylbenzene (DVB) cyclohexane solution was added, and polymerization continued for another 30 min. During this period, the polymerization temperature was maintained below 68°C, and the Mooney viscosity of the polymer was continuously analyzed until the set requirements were met. Finally, the resin was discharged, and a small amount of water was added to terminate the lithium activation. Then, 0.96 g of 1076 antioxidant was added and mixed thoroughly. The resin was then subjected to hot water coagulation, dehydration, and drying to obtain 216.0 g of transparent block raw rubber (labeled HVDR-1#). Gel permeation chromatography (GPC) analysis of the raw rubber is shown below. Figure 1 H 1 -NMR spectrum see Figure 2 The contents of vinyl units are shown in Table 1.

[0048] Example 2

[0049] The relevant process conditions in Implementation 1 were kept unchanged, except that 360 mL of isoprene monomer was added. As a result, 243.3 g of raw rubber (labeled as HVDR-2#) was obtained, and the technical specifications are shown in Table 1.

[0050] Example 3

[0051] The relevant process conditions in Implementation 1 were kept unchanged, except that 0.90 mL of tetrahydrofurfuryl ether, 3.5 mL of NBL, 1.9 mL of cyclohexane solution of DVB, 330 mL of butadiene, and 16 mL of isoprene were added. As a result, 215.4 g of raw rubber (labeled as HVDR-3#) was obtained. The technical specifications of the raw rubber are shown in Table 1.

[0052] Example 4

[0053] The relevant process conditions in Implementation 3 remain unchanged, except that 1.10 mL of tetrahydrofurfuryl ether, 30 mL of butadiene, and 310 mL of isoprene are added. 228.3 g of raw rubber (labeled HVDR-4#) is added, and its technical specifications are shown in Table 1.

[0054] Example 5

[0055] The relevant process conditions in Implementation 1 were kept unchanged, except that 1.3 mL of tetrahydrofurfuryl ethyl ether, 3.6 mL of NBL, 1.9 mL of cyclohexane solution of DVB, 170 mL of butadiene, and 200 mL of isoprene were added. The result was 241.6 g of raw rubber (labeled as HVDR-5#). The technical specifications of the raw rubber are shown in Table 1.

[0056] Example 6

[0057] The relevant process conditions in Implementation 5 were kept unchanged, except that 1.5 mL of tetrahydrofurfuryl ethyl ether, 2.0 mL of cyclohexane solution of DVB, 250 mL of butadiene, and 110 mL of isoprene were added, and the continuous feeding time was 50 min. As a result, 229.6 g of raw rubber (labeled as HVDR-6#) was obtained, and the technical indicators of the raw rubber are shown in Table 1.

[0058] Comparative Example-1#

[0059] The relevant process conditions in Implementation 3 were kept unchanged, except that the continuous feeding time of monomer and NBL was 32 min, and the maximum polymerization temperature was 73℃. As a result, 228.8 g of raw rubber (labeled as Comparison-1#) was obtained, and the technical indicators of the raw rubber are shown in Table 1.

[0060] Comparative Example-2#

[0061] The relevant process conditions in Implementation 6 were kept unchanged, except that 1.7 mL of tetrahydrofurfuryl ethyl ether was added. As a result, 229.3 g of raw rubber (standardization comparison-2#) was obtained, and the technical indicators of the raw rubber are shown in Table 1.

[0062] Comparative Example-3#

[0063] The relevant process conditions in Implementation 6 were kept unchanged, except for the addition of 1.4 mL of cyclohexane solution of DVB. The resulting raw rubber (standardization comparison -3#) was prepared, and its technical specifications are shown in Table 1.

[0064] Comparative Example-4#

[0065] The relevant process conditions in Implementation 6 were kept unchanged, except that 0.15 mL of hindered amine 1,8-diazabicyclo[5.4.0]undecene (DBU) was added.

[0066] The resulting raw rubber yielded 197.8g, with a monomer conversion rate of 86.2%. Technical specifications of the raw rubber (standardization comparison - 3#) are shown in Table 1.

[0067] Comparative Example-5#

[0068] The relevant process conditions in Exercise 6 were kept unchanged, except for the addition of 2.2 mL of cyclohexane solution of DVB. The resulting adhesive solution exhibited gelation and poor flow properties.

[0069] Table 1. Technical specifications of raw rubber in the examples and comparative examples.

[0070]

[0071]

[0072] Note: *Based on polybutadiene units; **Based on polyisoprene units.

[0073] Example 7

[0074] The trial samples in Table 1, such as HVDR-1#, HVDR-2#, HVDR-3#, HVDR-4#, HVDR-5#, HVDR-6#, Comparison-1#, Comparison-2#, Comparison-3#, Comparison-4#, as well as the molybdenum BR trial produced by the Rubber Department of Qilu Petrochemical of China Petrochemical Corporation and the isoprene rubber IR2200 produced by JSR Corporation of Japan, were mixed with carbon black, sulfur, accelerators and other minor ingredients according to national standards, vulcanized and tested. Their physical properties are shown in Table 2.

[0075] Table 2 Physical properties of vulcanizates

[0076]

[0077] Note: 1) Formula (parts by weight): raw rubber, 100 parts; stearic acid, 2.5 parts; zinc oxide, 5 parts; TDAE rubber oil, 15 parts; accelerator TBBS, 1.5 parts; sulfur, 1.8 parts; N330, 50 parts.

[0078] 2) Vulcanization conditions: 145℃×45min.

[0079] Compared to the other six types of rubber, the HVDR of this invention has excellent anti-slip properties, low heat generation, and low rolling resistance.

Claims

1. A conjugated diene rubber with branching, broad distribution, and high side alkenyl content, characterized in that: It has the following structure expression: ； Formula 1 in, It is a conjugated diene block, and the total mass fraction of 1,2-addition units and 3,4-addition units in the conjugated diene block is 65%~83%; D is a branched node; The mass of the branched nodes accounts for 0.05 to 0.08% of the total mass of the conjugated diene blocks.

2. The conjugated diene rubber with branching, broad distribution, and high side alkenyl content according to claim 1, characterized in that: The conjugated diene block is composed of at least one conjugated diene unit selected from butadiene, isoprene and isoprene units.

3. A conjugated diene rubber with branching, broad distribution, and high side alkenyl content according to claim 1 or 2, characterized in that: The conjugated diene block is composed of butadiene units and isoprene units in a mass percentage ratio of 5~95%:95~5%.

4. A conjugated diene rubber with branching, broad distribution, and high side alkenyl content according to claim 1, characterized in that: The branching nodes are divinylbenzene units.

5. A conjugated diene rubber with branching, broad distribution, and high side alkenyl content according to claim 1, 2, or 4, characterized in that: Molecular weight distribution index M w / M n =1.9~2.5, Mooney viscosity is ML （1+4） =45~55.

6. A method for preparing a conjugated diene rubber with branching, broad distribution, and high side alkenyl content as described in any one of claims 1 to 5, characterized in that: The initiator and conjugated diene monomer are simultaneously and uniformly added to a solution system containing a structure modifier to carry out the polymerization reaction. After the conjugated diene monomer is completely added, divinylbenzene monomer is added to continue the polymerization reaction. After the polymerization reaction is completed, the product is obtained.

7. The method for preparing a conjugated diene rubber with branching, broad distribution, and high side alkenyl content according to claim 6, characterized in that: The initiator is an alkyl lithium; The structure modifier is tetrahydrofurfuryl ethyl ether and / or tetrahydrofurfuryl ethyl ether.

8. A method for preparing a conjugated diene rubber with branching, broad distribution, and high side alkenyl content according to claim 6 or 7, characterized in that: The fraction of the structure modifier in the solution system is 0.03~0.06%.

9. The method for preparing a conjugated diene rubber with branching, broad distribution, and high side alkenyl content according to claim 6, characterized in that: The initiator and conjugated diene monomer are added to the solution system containing the structure modifier within 40-60 minutes.

10. The method for preparing a conjugated diene rubber with branching, broad distribution, and high side alkenyl content according to claim 7, characterized in that: During the polymerization process, the pressure is controlled at 3~4.5 bar, the initial polymerization temperature is controlled at 50~55℃, and the maximum polymerization temperature is controlled below 68℃.

11. The application of a conjugated diene rubber with branching, broad distribution, and high side alkenyl content as described in any one of claims 1 to 6, characterized in that: It is used as a base rubber for shoe soles, tire sidewalls, or tire treads.

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