Preparation of high molecular damping brominated grafting agent and high damping brominated branched butyl rubber

Abstract

This invention discloses a polymeric damping brominated grafting agent, which is a linear block copolymer composed of p-alkylstyrene, allyl halide, and isoprene, and its preparation method. This invention also discloses a method for preparing highly damping brominated branched butyl rubber using the aforementioned polymeric damping brominated grafting agent. In the preparation process of highly damping brominated branched butyl rubber, this invention eliminates the emission of volatile organic compounds (VOCs) and the byproduct HBr, avoiding harm to humans and the environment. It also eliminates the need for an alkaline washing and recovery process for the byproduct HBr. The preparation method is green and environmentally friendly, with a short process flow, low production cost, and suitability for industrial production.

Description

Technical Field

[0001] This invention relates to the preparation of a polymeric damping brominated grafting agent and a highly damping brominated branched butyl rubber. Background Technology

[0002] With the rapid development of modern science and technology, mechanical equipment is trending towards high frequency and high speed. While bringing convenience to daily production and life, this has also generated a series of problems, such as high-frequency vibration and noise. These problems not only accelerate the fatigue damage of mechanical structural materials and shorten their service life, but also affect people's daily lives to a certain extent. Therefore, developing high-performance, high-efficiency damping materials and improving their damping and vibration reduction applications is crucial for improving the operating environment of machinery. Due to the unique viscoelasticity of polymers, rubber damping materials have significant damping effects in vibration reduction, noise reduction, and improving the human-machine working environment. They have been widely used in many fields such as high-speed rail, aerospace, naval vessels, mechanical engineering, automobiles, and electronics. In particular, the data storage systems in various IT equipment such as servers, computers, workstations, and switches are subject to vibration and noise from the fan rotation, which seriously affects the service life of hard drives. The demand for high-efficiency damping and vibration reduction products is very urgent. Furthermore, as electronic equipment faces increasingly complex operating environments with lower and higher temperatures, extremely high requirements are placed on rubber damping materials.

[0003] Brominated butyl rubber (BIIR) is produced by introducing bromine atoms into the molecular chain of butyl rubber (IIR) through an electrophilic substitution reaction under the influence of molecular bromine. Compared to IIR, BIIR, in addition to possessing the same excellent airtightness, also exhibits better adhesion, faster vulcanization speed, good thermal stability, and corrosion resistance, enabling its use in extreme environments such as strong corrosion or high temperatures. Furthermore, the introduction of bromine atoms increases the polarity of the molecular chain, leading to increased relaxation resistance and greater internal friction, resulting in excellent damping performance. Therefore, it is one of the most widely used basic damping rubbers. However, brominated butyl rubber currently suffers from drawbacks such as insufficient damping value, unstable damping performance, a limited effective damping temperature range, and unsatisfactory mechanical properties. These limitations prevent it from meeting the damping performance requirements of large equipment and precision instruments, thus becoming a bottleneck for the expanded application of brominated butyl rubber materials.

[0004] In the prior art, the preparation methods of polymer damping materials mainly include blending, copolymerization, interpenetrating polymer networks, and adding organic small molecule functional damping agents.

[0005] CN112574333A, CN102229724A, CN102775659B, CN 106749816A, CN105906956B, CN113969031A, CN103113682A, CN103113682A, CN201110165757.2, Tao Gang et al. (Polymer Materials Science and Engineering, 2013, 29(11): 114-118), Liao Mingyi et al. (Journal of Dalian Maritime University, 2008, 34(2): 83-86) and other literatures have broadened the effective damping temperature range of rubber and improved the damping performance of rubber to a certain extent through blending, copolymerization and interpenetrating network polymer methods. However, these methods still have certain limitations. They can lead to a decrease in the mechanical properties of modified materials, complex processes, difficulties in actual operation, large addition amounts, high costs, difficulty in removing organic solvents, and environmental pollution. Summary of the Invention

[0006] One of the objectives of this invention is to provide a maximum damping factor tanδ max A method for preparing high-damping brominated branched butyl rubber with a strength ≥1.8. This invention first synthesizes a macromolecular brominating agent with anionic reactivity; secondly, using alkyllithium as an initiator, a high-molecular-weight damping brominated grafting agent is synthesized from p-alkylstyrene and the macromolecular brominating agent; finally, the high-molecular-weight damping brominated grafting agent, isobutylene, and isoprene are cationicly polymerized in a catalytic system of alkyl aluminum halide and protic acid to prepare high-damping brominated branched butyl rubber. This method solves the problems of low damping and bromine structural isomer rearrangement in butyl rubber, not only avoiding the damage to the mechanical properties and permeability of butyl rubber caused by the damping brominated grafting agent, but also improving the damping performance and tensile strength of butyl rubber. This invention prepares high-damping brominated branched butyl rubber through addition polymerization, rather than the ion substitution reaction used in the prior art. This not only solves the problem of the stability of the bromine structure in brominated butyl rubber, but also greatly improves the damping performance of brominated butyl rubber by introducing alkyl phenyl groups. Furthermore, it also improves the tensile strength and air tightness of brominated butyl rubber.

[0007] In this invention, "%" refers to mass percentage.

[0008] As one aspect of the present invention, a polymeric damping brominated grafting agent is disclosed, which is a linear block copolymer composed of p-alkylstyrene, allyl halide, and isoprene, and its general structural formula is shown in Formula I:

[0009]

[0010] Wherein: I is a small molecule isoprene segment; R1 is a C1-C5 alkyl group; R2 is hydrogen (H) or a C1-C4 alkyl group; n is the number of repeating units: n≥1. The number average molecular weight (Mn) of the polymeric damping brominated grafting agent is 40,000-50,000. The mass percentage of bromine in the polymeric damping brominated grafting agent is 3-4%.

[0011] As another aspect of the present invention, a method for preparing the above-mentioned polymeric damping brominated grafting agent is provided, comprising:

[0012] Based on 100% of the total mass of reactants, 300%–400% solvent, 50%–70% p-alkylstyrene, and 0.4%–0.6% structure modifier are added sequentially to a reactor. The temperature is raised to 60–70°C, and then an initiator is added, reacting for 60–80 minutes. Next, 30%–50% allyl halide and 0.2%–0.4% structure modifier are added to the reactor, and the temperature is raised to 80–90°C, reacting for 100–120 minutes. Finally, 2–4 parts of isoprene are added to the reactor for end-capping, reacting for 20–30 minutes until no free monomers remain. The resulting solution is then wet-coagulated and dried to obtain a high-molecular-weight damping brominated grafting agent. Preferably, the reactor is purged with argon gas 2–4 times before adding the reactants.

[0013] As another aspect of the present invention, a method for preparing high-damping brominated branched butyl rubber is disclosed, comprising: adding 100%–200% mixed solvent (diluent / solvent V:V ratio of 70–30 / 30–70) and 3%–6% high-molecular-weight damping brominated grafting agent to a reaction vessel, based on 100% of the mass of the reactant monomer isobutylene, stirring and dissolving for 30–50 minutes until the grafting agent is completely dissolved; then cooling to -80 to -70°C, and subsequently adding 100%–200% of the diluent / solvent mixture sequentially. The reaction mixture, consisting of 100% isobutylene and 3%–5% isoprene, is stirred until the polymerization system temperature drops to -90 to -80°C. Then, 10%–20% diluent and 0.05%–0.3% co-initiator are mixed and aged at -100 to -90°C for 50–60 minutes, and then added to the polymerization system. The mixture is stirred and reacted for 2.0–3.0 hours. Finally, 3%–5% terminator is added, and the mixture is discharged, coagulated, washed, and dried to obtain a high-damping brominated branched butyl rubber product. Preferably, nitrogen is purged 3–5 times before adding the reactants to the reactor.

[0014] The p-alkylstyrene described in this invention is one of p-methylstyrene, p-ethylstyrene, p-propylstyrene, p-n-butylstyrene, p-isobutylstyrene, and p-isopentylstyrene, with p-methylstyrene being preferred.

[0015] The allyl halide described in this invention is one of allyl bromide, 2-methyl-1-allyl bromide, 2-ethyl-1-allyl bromide, 2-propyl-1-allyl bromide, and 2-butyl-1-allyl bromide, preferably allyl bromide.

[0016] The initiator described in this invention is a hydrocarbon-based monolithium compound, namely RLi, wherein R is a saturated aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic group, or a complex group containing 1 to 20 carbon atoms. This hydrocarbon-based monolithium compound is selected from one of n-butyllithium, sec-butyllithium, methylbutyllithium, phenylbutyllithium, naphthenelithium, cyclohexyllithium, and dodecyllithium, preferably n-butyllithium. The amount of organolithium added is determined by the molecular weight of the designed polymer.

[0017] The structure modifier described in this invention is a polar organic compound that produces a solvation effect in the polymerization system, enabling it to adjust the reactivity ratio of styrene and isoprene, thus allowing them to copolymerize randomly. This type of polar organic compound is selected from one of diethylene glycol dimethyl ether (DGE), tetrahydrofuran (THF), diethyl ether, ethyl methyl ether, anisole, diphenyl ether, diethylene glycol dimethyl ether (DME), and triethylamine, preferably tetrahydrofuran (THF).

[0018] The diluent described in this invention is a haloalkane, wherein the halogen atom in the haloalkane can be chlorine, bromine, or fluorine; and the number of carbon atoms in the haloalkane is C1-C4. This haloalkane is selected from one of chloromethane, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloropropane, heptachloropropane, fluoromethane, difluoromethane, tetrafluoroethane, carbon hexafluoride, and fluorobutane, preferably chloromethane.

[0019] The co-initiator described in this invention is composed of alkyl aluminum halides and protic acids in different proportions. The alkyl aluminum halide is selected from at least one of diethylaluminum chloride, diisobutylaluminum chloride, dichloromethylaluminum, sesquiethylaluminum chloride, sesquiisobutylaluminum chloride, dichloro-n-propylaluminum, dichloroisopropylaluminum, dimethylaluminum chloride, and ethylaluminum chloride, preferably sesquiethylaluminum chloride. The protic acid is selected from one of HCl, HF, HBr, H2SO4, H2CO3, H3PO4, and HNO3, preferably HCl. The total amount of co-initiator added is 0.01% to 0.5%, and the molar ratio of protic acid to alkyl aluminum halide is 0.01:1 to 0.1:1.

[0020] The terminating agent described in this invention may be selected from one or more of methanol, ethanol, and butanol.

[0021] The polymerization reactions described in this invention are all carried out in an oxygen-free and anhydrous environment, preferably in an inert gas environment. Both the polymerization and dissolution processes are completed in a hydrocarbon solvent. The solvent described in this invention is a hydrocarbon solvent, including straight-chain alkanes, aromatics, and cycloalkanes. This hydrocarbon solvent is selected from one of pentane, hexane, octane, heptane, cyclohexane, benzene, toluene, xylene, and ethylbenzene, with pentane being preferred.

[0022] The polymeric damping brominated grafting agent prepared in this invention combines p-methylphenyl, methyl, and bromine atoms onto a single macromolecular chain via anionic polymerization. This well-organized arrangement of the p-methylphenyl, methyl, and bromine atoms results in a structure characterized by high rigidity, strong steric hindrance, and high adsorption force, along with high isotacticity. These structural features produce a significant "synergistic effect" in improving the damping properties of the material, greatly enhancing the damping performance of brominated branched butyl rubber and enabling the preparation of a maximum damping factor tanδ. max High-damping brominated branched butyl rubber with a resistance of ≥1.8.

[0023] The high-damping brominated branched butyl rubber prepared by this invention is generated by addition polymerization of a high-molecular-weight damping brominated grafting agent, rather than by ionic substitution. The p-methylphenyl, methyl, and primary bromine structures in the grafting agent are embedded in the main chain segment of the butyl rubber, which blocks the conditions for molecular structure isomerization and improves the stability of the damping performance of the brominated branched butyl rubber.

[0024] The polymeric damping brominated grafting agent prepared in this invention contains highly regular nonpolar p-methylbenzene ring groups and methyl groups. The superposition of its "group effect" and "structural effect" not only avoids the problem of butyl rubber's mechanical properties and air tightness decreasing due to the widening of molecular weight distribution caused by branching, but also improves the tensile strength and air tightness of butyl rubber.

[0025] This invention produces high-damping brominated branched butyl rubber without the emission of volatile organic compounds (VOCs) or byproduct HBr, thus avoiding harm to humans and the environment. It also eliminates the need for alkaline washing and recovery of the byproduct HBr. The preparation method is green and environmentally friendly, with a short process flow, low production cost, and is suitable for industrial production. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] (1) Source of raw materials:

[0028]

[0029] All other reagents are commercially available industrial products.

[0030] (2) Analysis and testing methods:

[0031] Bromine content determination: Weigh 10 mg of sample and use a Q600 TG / DTG thermogravimetric analyzer at a heating rate of 10℃ / min in a nitrogen atmosphere with a flow rate of 50 mL / min to perform thermal degradation of the sample. The first stage of thermal degradation involves the debromination of bromine-containing units in the sample to form HBr. The bromine content (X) in the sample is then inferred from the percentage of HBr removed, using the following formula:

[0032]

[0033] In the formula: Y—percentage content of the sample at 220℃; 79.904—relative atomic mass of bromine; 1.008—relative atomic mass of hydrogen.

[0034] Molecular weight determination: Molecular weight was determined using a Waters 2414 gel permeation chromatography (GPC) system (Waters, Inc., USA). A polystyrene standard was used as the calibration curve. The mobile phase was tetrahydrofuran, the column temperature was 40℃, the sample concentration was 1 mg / ml, the injection volume was 50 μL, the elution time was 40 min, and the flow rate was 1 ml·min⁻¹.

[0035] Air tightness determination: An automated air tightness tester was used to determine the air permeability number according to ISO 2782:1995. The test gas was N2, the test temperature was 23℃, and the test sample was an 8cm diameter circular sea sheet with a thickness of 1mm.

[0036] Dynamic mechanical analysis (DMA): Measurements were performed in tensile mode on a Netzsch 242C dynamic mechanical analyzer (Germany). Sample dimensions were 10 mm long, 6 mm wide, and 2 mm thick. The temperature range was -90℃ to 90℃, with a heating rate of 3℃ / min. Data were analyzed at a frequency of 10 Hz.

[0037] Tensile strength: The method specified in standard GB / T528-2009 shall be applied.

[0038] Example 1

[0039] (1) Preparation of polymeric damping brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was purged twice. Then, 3000g of pentane, 500g of p-methylstyrene, and 4.0g of THF were added to the polymerization reactor in sequence. The temperature was raised to 60℃, and 17.1mmol of n-butyllithium was added to start the reaction for 60min. Then, 500g of 2-methyl-1-allyl bromide and 2.0g of THF were added to the polymerization reactor. The temperature was raised to 80℃ and the reaction was carried out for 100min. Finally, 20g of isoprene was added to the polymerization reactor and the end-capping reaction was carried out for 20min until no free monomers were present. The glue solution was wet coagulated and dried to obtain the polymeric damping brominated grafting agent (Mn is 40200, bromine content is 3.95%). The polymeric damping brominated grafting agent obtained in this embodiment, in the general formula I, I is isoprene; R1 is methyl (CH3); R2 is methyl (CH3); n is the number of repeating units: n≥1.

[0040] (2) Preparation of high-damping brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen gas was purged three times. 700g of dichloromethane, 300g of pentane, and 15g of high-molecular-weight damping brominated grafting agent were added to the polymerization reactor and stirred for 30 minutes until completely dissolved. Then, the temperature was lowered to -70℃, and 500g of monochloromethane, 500g of isobutylene, and 15g of isoprene were added sequentially. The mixture was stirred until the polymerization system temperature dropped to -80℃. Then, 50g of monochloromethane, 0.95g of sesquiethylaluminum chloride, and 0.013g of HCl were mixed and aged at -90℃ for 50 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.0 hours. Finally, 15g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0041] Example 2

[0042] (1) Preparation of polymeric damping brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was purged twice. Then, 3200g of pentane, 540g of p-methylstyrene, and 4.3g of THF were added to the polymerization reactor in sequence. The temperature was raised to 61℃, and 18.7mmol of n-butyllithium was added to start the reaction for 62min. Then, 460g of allyl bromide and 2.3g of THF were added to the polymerization reactor, and the temperature was raised to 82℃ and the reaction was carried out for 104min. Finally, 22g of isoprene was added to the polymerization reactor and the end-capping reaction was carried out for 22min until no free monomers were present. The glue solution was wet coagulated and dried to obtain polymeric damping brominated grafting agent (Mn is 41800, bromine content is 3.76%). The polymeric damping brominated grafting agent obtained in this embodiment, in the general formula I, I is isoprene; R1 is methyl (CH3); R2 is hydrogen atom (H); n is the number of repeating units: n≥1.

[0043] (2) Preparation of high-damping brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged three times. Then, 650g of dichloromethane, 350g of pentane, and 18g of high-molecular-weight damping brominated grafting agent were added to the polymerization reactor and stirred for 33 minutes until completely dissolved. Next, the temperature was lowered to -71℃, and then 600g of monochloromethane, 500g of isobutylene, and 17g of isoprene were added sequentially. The mixture was stirred until the polymerization system temperature dropped to -81℃. Then, 60g of monochloromethane, 1.32g of sesquiethylaluminum chloride, and 0.024g of HCl were mixed and aged at -91℃ for 51 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.2 hours. Finally, 17g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0044] Example 3

[0045] (1) Preparation of polymeric damping brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was purged three times. Then, 3500g of pentane, 580g of p-methylstyrene, and 4.8g of THF were added to the polymerization reactor in sequence. The temperature was raised to 63℃, and 19.8mmol of n-butyllithium was added to start the reaction for 68min. Then, 420g of allyl bromide and 2.6g of THF were added to the polymerization reactor, and the temperature was raised to 83℃ and the reaction was carried out for 108min. Finally, 27g of isoprene was added to the polymerization reactor and the end-capping reaction was carried out for 24min until no free monomers were present. The glue solution was wet coagulated and dried to obtain polymeric damping brominated grafting agent (Mn is 43100, bromine content is 3.61%). The polymeric damping brominated grafting agent obtained in this embodiment, in the general formula I, I is isoprene; R1 is methyl (CH3); R2 is hydrogen atom (H); n is the number of repeating units: n≥1.

[0046] (2) Preparation of high-damping brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged four times. Then, 600g of dichloromethane, 400g of pentane, and 20g of high-molecular-weight damping brominated grafting agent were added to the polymerization reactor and stirred for 36 minutes until completely dissolved. Then, the temperature was lowered to -73℃, and 700g of monochloromethane, 500g of isobutylene, and 19g of isoprene were added sequentially. The mixture was stirred until the polymerization system temperature dropped to -83℃. Then, 70g of monochloromethane, 1.48g of sesquiethylaluminum chloride, and 0.036g of HCl were mixed and aged at -93℃ for 53 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.3 hours. Finally, 18g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0047] Example 4

[0048] (1) Preparation of polymeric damping brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was purged three times. Then, 3600g of pentane, 600g of p-methylstyrene, and 5.0g of THF were added to the polymerization reactor in sequence. The temperature was raised to 65℃, and 20.8mmol of n-butyllithium was added to start the reaction for 70min. Then, 400g of allyl bromide and 3.0g of THF were added to the polymerization reactor, and the temperature was raised to 85℃ and the reaction was carried out for 110min. Finally, 30g of isoprene was added to the polymerization reactor and the end-capping reaction was carried out for 26min until no free monomers were present. The glue solution was wet coagulated and dried to obtain polymeric damping brominated grafting agent (Mn is 44900, bromine content is 3.52%). The polymeric damping brominated grafting agent obtained in this embodiment, in the general formula I, I is isoprene; R1 is methyl (CH3); R2 is hydrogen atom (H); n is the number of repeating units: n≥1.

[0049] (2) Preparation of high-damping brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen gas was purged four times. Then, 500g of dichloromethane, 500g of pentane, and 24g of high-molecular-weight damping brominated grafting agent were added to the polymerization reactor and stirred for 39 minutes until completely dissolved. Then, the temperature was lowered to -75℃, and 800g of monochloromethane, 500g of isobutylene, and 20g of isoprene were added sequentially. The mixture was stirred until the polymerization system temperature dropped to -85℃. Then, 80g of monochloromethane, 1.55g of sesquiethylaluminum chloride, and 0.047g of HCl were mixed and aged at -95℃ for 55 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.5 hours. Finally, 20g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0050] Example 5

[0051] (1) Preparation of polymeric damping brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was purged three times. Then, 3700g pentane, 630g p-isopentylstyrene, and 5.4g THF were added sequentially to the polymerization reactor. The temperature was raised to 66℃, and 21.7 mmol of n-butyllithium was added to initiate a reaction for 75 min. Next, 370g allyl bromide and 3.4g THF were added to the polymerization reactor, and the temperature was raised to 86℃ for a reaction of 113 min. Finally, 33g isoprene was added to the polymerization reactor for a capping reaction for 27 min until no free monomers remained. The resulting solution was wet-coagulated and dried to obtain a polymeric damping brominated grafting agent (Mn = 46100, bromine content = 3.38%). In the polymeric damping brominated grafting agent obtained in this example, in Formula I, I represents isoprene; R1 represents isopentyl (C5H) 11 R2 is a hydrogen atom (H); n is the number of repeating units: n≥1.

[0052] (2) Preparation of high-damping brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen gas was purged four times. Then, 400g of dichloromethane, 600g of pentane, and 26g of high-molecular-weight damping brominated grafting agent were added to the polymerization reactor and stirred for 42 minutes until completely dissolved. Then, the temperature was lowered to -77℃, and 900g of monochloromethane, 500g of isobutylene, and 22g of isoprene were added sequentially. The mixture was stirred until the polymerization system temperature dropped to -86℃. Then, 90g of monochloromethane, 1.69g of sesquiethylaluminum chloride, and 0.053g of HCl were mixed and aged at -96℃ for 56 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.6 hours. Finally, 22g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0053] Example 6

[0054] (1) Preparation of polymeric damping brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was purged four times. Then, 3900g of pentane, 660g of p-methylstyrene, and 5.7g of THF were added to the polymerization reactor in sequence. The temperature was raised to 68℃, and 22.8mmol of n-butyllithium was added to start the reaction for 77min. Then, 340g of allyl bromide and 3.7g of THF were added to the polymerization reactor, and the temperature was raised to 88℃ for 118min. Finally, 35g of isoprene was added to the polymerization reactor for end-capping reaction for 28min until no free monomers were present. The gel was wet coagulated and dried to obtain the polymeric damping brominated grafting agent (Mn is 48700, bromine content is 3.24%). The polymeric damping brominated grafting agent obtained in this embodiment, in the general formula I, I is isoprene; R1 is methyl (CH3); R2 is hydrogen atom (H); n is the number of repeating units: n≥1.

[0055] (2) Preparation of high-damping brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged five times. Then, 350g of dichloromethane, 650g of pentane, and 28g of high-molecular-weight damping brominated grafting agent were added to the polymerization reactor and stirred for 46 minutes until completely dissolved. Then, the temperature was lowered to -78℃, and 950g of monochloromethane, 500g of isobutylene, and 23g of isoprene were added sequentially. The mixture was stirred until the polymerization system temperature dropped to -88℃. Then, 95g of monochloromethane, 1.75g ​​of sesquiethylaluminum chloride, and 0.063g of HCl were mixed and aged at -98℃ for 58 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.8 hours. Finally, 23g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0056] Example 7

[0057] (1) Preparation of polymeric damping brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was purged four times. Then, 4000g of pentane, 700g of p-n-butylstyrene, and 6.0g of THF were added to the polymerization reactor in sequence. The temperature was raised to 70℃, and 23.2 mmol of n-butyllithium was added to start the reaction for 80 min. Then, 300g of 2-butyl-1-allyl bromide and 4.0g of THF were added to the polymerization reactor. The temperature was raised to 90℃ and the reaction was carried out for 120 min. Finally, 40g of isoprene was added to the polymerization reactor and the end-capping reaction was carried out for 30 min until no free monomers were present. The glue solution was wet coagulated and dried to obtain the polymeric damping brominated grafting agent (Mn is 49500, bromine content is 3.03%). The polymeric damping brominated grafting agent obtained in this embodiment, in the general formula I, I is isoprene; R1 is butyl (C4H9); R2 is butyl (C4H9); n is the number of repeating units: n≥1.

[0058] (2) Preparation of high-damping brominated branched butyl rubber: First, in a jacketed 4L stainless steel reactor, nitrogen was purged five times. Then, 300g of dichloromethane, 700g of pentane, and 30g of high-molecular-weight damping brominated grafting agent were added to the polymerization reactor and stirred for 50 minutes until completely dissolved. Next, the temperature was lowered to -80℃, and then 1000g of monochloromethane, 500g of isobutylene, and 25g of isoprene were added sequentially. The mixture was stirred until the polymerization system temperature dropped to -90℃. Then, 100g of monochloromethane, 1.75g ​​of sesquiethylaluminum chloride, and 0.085g of HCl were mixed and aged at -100℃ for 60 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 3.0 hours. Finally, 25g of ethanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0059] Comparative Example 1

[0060] (1) Preparation of polymeric damping brominated grafting agent: Other conditions are the same as in Example 1, except that: p-methylstyrene is not added during the preparation of the polymeric damping brominated grafting agent, but styrene is added, with an addition amount of 500g, that is: first, in a 15L stainless steel reactor with a jacket, argon gas is purged twice, and 3000g pentane, 500g styrene, and 4.0g THF are added to the polymerization reactor in sequence, the temperature is raised to 60℃, and 17.1mmol n-butyllithium is added to start the reaction for 60min; then 500g 2-methyl-1-allyl bromide and 2.0g THF are added to the polymerization reactor. THF was heated to 80℃ and reacted for 100 min. Finally, 20 g of isoprene was added to the polymerization reactor, and the end-capping reaction was carried out for 20 min until no free monomers were present. The solution was then wet-coagulated and dried to obtain polymeric damping brominated grafting agent-1 (Mn is 40100, bromine content is 3.90%). In the polymeric damping brominated grafting agent obtained in this comparative example, in the general formula I, I is isoprene; R1 is a hydrogen atom (H); R2 is a methyl group (CH3); n is the number of repeating units: n≥1.

[0061] (2) Preparation of high-damping brominated branched butyl rubber: Other conditions are the same as in Example 1, except that: no polymeric damping brominated grafting agent is added during the preparation of high-damping brominated branched butyl rubber; instead, polymeric damping brominated grafting agent-1 is added, with an addition amount of 15g. That is: first, nitrogen gas is purged three times in a 4L stainless steel reactor with a jacket, and then 700g of dichloromethane, 300g of pentane, and polymeric damping brominated grafting agent-1 are added to the polymerization reactor. 15g of methanol was added and stirred for 30 minutes until completely dissolved. Then, the temperature was lowered to -70℃, followed by the sequential addition of 500g of chloromethane, 500g of isobutylene, and 15g of isoprene. The mixture was stirred until the polymerization system temperature reached -80℃. Then, 50g of chloromethane, 0.95g of sesquiethylaluminum chloride, and 0.013g of HCl were mixed and aged at -90℃ for 50 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.0 hours. Finally, 15g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0062] Comparative Example 2

[0063] (1) Preparation of polymeric damping brominated grafting agent: Other conditions are the same as in Example 2, except that the amount of p-methylstyrene added in the preparation of polymeric damping brominated grafting agent is 300g, that is: firstly, in a 15L stainless steel reactor with a jacket, argon gas is purged twice, and 3200g pentane, 300g p-methylstyrene, and 4.3g THF are added to the polymerization reactor in sequence, the temperature is raised to 61°C, and 18.7mmol n-butyllithium is added to start the reaction for 62min; then 460g allyl bromide and 2.3g THF are added to the polymerization reactor, the temperature is raised to 82°C, and the reaction is carried out for 104min; finally, 22g isoprene is added to the polymerization reactor, and the end-capping reaction is carried out for 22min until no free monomers are present. The glue solution is wet coagulated and dried to obtain polymeric damping brominated grafting agent-2 (Mn is 35000, bromine content is 3.72%). The polymeric damping brominated grafting agent obtained in this comparative example, in the general formula described in Formula I, I is isoprene; R1 is methyl (CH3); R2 is hydrogen atom (H); n is the number of repeating units: n≥1.

[0064] (2) Preparation of high-damping brominated branched butyl rubber: Other conditions are the same as in Example 2, except that: no polymeric damping brominated grafting agent is added during the preparation of high-damping brominated branched butyl rubber; instead, polymeric damping brominated grafting agent-2 is added, with an addition amount of 18g. That is: first, nitrogen gas is purged three times in a 4L stainless steel reactor with a jacket, and then 650g of dichloromethane, 350g of pentane, and polymeric damping brominated grafting agent-2 are added to the polymerization reactor. 18g of methanol was added and stirred for 33 minutes until completely dissolved. Then, the temperature was lowered to -71℃, followed by the sequential addition of 600g of chloromethane, 500g of isobutylene, and 17g of isoprene. The mixture was stirred until the polymerization system temperature reached -81℃. Then, 60g of chloromethane, 1.32g of sesquiethylaluminum chloride, and 0.024g of HCl were mixed and aged at -91℃ for 51 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.2 hours. Finally, 17g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0065] Comparative Example 3

[0066] (1) Preparation of polymeric damping brominated grafting agent: Other conditions are the same as in Example 3, except that: free radical polymerization is used in the preparation of polymeric damping brominated grafting agent, and dicumyl peroxide (DCP) is added instead of n-butyllithium as the initiator. The amount added is 19.8 mmol, that is: first, in a 15L stainless steel reactor with a jacket, argon gas is purged three times, and 3500g pentane, 580g p-methylstyrene, and 4.8g THF are added to the polymerization reactor in sequence. The temperature is raised to 63°C, and 19.8 mmol of DCP is added to start the reaction for 68 min; then 420g allyl bromide and 2.6g THF are added to the polymerization reactor. The THF reaction was then heated to 83°C and reacted for 108 min. Finally, 27 g of isoprene was added to the polymerization reactor, and the end-capping reaction was carried out for 24 min until no free monomers were present. The solution was then wet-coagulated and dried to obtain polymeric damping brominated grafting agent-3 (Mn is 37000, bromine content is 2.65%). In the polymeric damping brominated grafting agent obtained in this comparative example, in the general formula I, I is isoprene; R1 is methyl (CH3); R2 is hydrogen atom (H); n is the number of repeating units: n≥1.

[0067] (2) Preparation of high-damping brominated branched butyl rubber: Other conditions are the same as in Example 3, except that: no polymeric damping brominated grafting agent is added during the preparation of high-damping brominated branched butyl rubber; instead, polymeric damping brominated grafting agent-3 is added, with an addition amount of 20g. That is: first, nitrogen gas is purged four times in a 4L stainless steel reactor with a jacket, and then 600g of dichloromethane, 400g of pentane, and polymeric damping brominated grafting agent-3 are added to the polymerization reactor. 20g of methanol was added and stirred for 36 minutes until completely dissolved. Then, the temperature was lowered to -73℃, followed by the sequential addition of 700g of chloromethane, 500g of isobutylene, and 19g of isoprene. The mixture was stirred until the polymerization system temperature reached -83℃. Then, 70g of chloromethane, 1.48g of sesquiethylaluminum chloride, and 0.036g of HCl were mixed and aged at -93℃ for 53 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.3 hours. Finally, 18g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0068] Comparative Example 4

[0069] (1) Preparation of polymeric damping brominated grafting agent: Other conditions were the same as in Example 4, except that isoprene monomer was not added for end-capping. Specifically, in a 15L stainless steel reactor with a jacket, argon gas was purged three times, and 3600g pentane, 600g p-methylstyrene, and 5.0g THF were added sequentially to the polymerization reactor. The temperature was raised to 65°C, and 20.8 mmol of n-butyllithium was added to start the reaction for 70 min. Then, 400g allyl bromide and 3.0g THF were added to the polymerization reactor, and the temperature was raised to 85°C for 110 min. Finally, the gel was wet-coagulated and dried to obtain polymeric damping brominated grafting agent-4 (Mn is 44800, bromine content is 3.41%). In the polymeric damping brominated grafting agent obtained in this comparative example, R1 is methyl (CH3); R2 is hydrogen atom (H); and n is the number of repeating units: n≥1.

[0070] (2) Preparation of high-damping brominated branched butyl rubber: Other conditions are the same as in Example 4, except that: no polymeric damping brominated grafting agent is added during the preparation of high-damping brominated branched butyl rubber; instead, polymeric damping brominated grafting agent-4 is added, with an addition amount of 24g. That is: first, nitrogen gas is purged four times in a 4L stainless steel reactor with a jacket, and then 500g of dichloromethane, 500g of pentane, and polymeric damping brominated grafting agent-4 are added to the polymerization reactor. 24g of methanol was added and stirred for 39 minutes until completely dissolved. Then, the temperature was lowered to -75℃, followed by the sequential addition of 800g of chloromethane, 500g of isobutylene, and 20g of isoprene. The mixture was stirred until the polymerization system temperature reached -85℃. Then, 80g of chloromethane, 1.55g of sesquiethylaluminum chloride, and 0.047g of HCl were mixed and aged at -95℃ for 55 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.5 hours. Finally, 20g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0071] Comparative Example 5

[0072] Preparation of high-damping brominated branched butyl rubber: Other conditions are the same as in Example 5, except that no high-molecular-weight damping brominated grafting agent is added during the preparation of high-damping brominated branched butyl rubber. Instead, 26g of p-methylstyrene is added directly. Specifically: First, in a 4L stainless steel reactor with a jacket, nitrogen is purged four times. Then, 400g of dichloromethane, 600g of pentane, and 26g of p-methylstyrene are added to the polymerization reactor and stirred for 42 minutes until completely dissolved. Then, when the temperature is lowered to -77°C, 900g of monochloromethane, 500g of isobutylene, and 22g of isoprene are added sequentially and stirred until the polymerization system temperature drops to -86°C. Then, 90g of monochloromethane, 1.69g of sesquiethylaluminum chloride, and HCl are added. 0.053g of the mixture was aged at -96℃ for 56 minutes, then added to the polymerization system and stirred for 2.6 hours. Finally, 22g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain a high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0073] Comparative Example 6

[0074] (1) Preparation of polymeric damping brominated grafting agent: Other conditions are the same as in Example 6, except that the amount of allyl bromide added in the preparation of polymeric damping brominated grafting agent is 200g, that is: firstly, in a 15L stainless steel reactor with a jacket, argon gas is purged 4 times, and 3900g pentane, 660g p-methylstyrene, and 5.7g THF are added to the polymerization reactor in sequence, the temperature is raised to 68℃, and 22.8mmol n-butyllithium is added to start the reaction for 77min; then 200g allyl bromide and 3.7g THF are added to the polymerization reactor, the temperature is raised to 88℃, and the reaction is carried out for 118min; finally, 35g isoprene is added to the polymerization reactor, and the end-capping reaction is carried out for 28min until no free monomers are present. The glue solution is wet coagulated and dried to obtain polymeric damping brominated grafting agent-5 (Mn is 42300, bromine content is 2.98%). The polymeric damping brominated grafting agent obtained in this comparative example, in the general formula described in Formula I, I is isoprene; R1 is methyl (CH3); R2 is hydrogen atom (H); n is the number of repeating units: n≥1.

[0075] (2) Preparation of high-damping brominated branched butyl rubber: Other conditions are the same as in Example 6, except that: no polymeric damping brominated grafting agent is added during the preparation of high-damping brominated branched butyl rubber; instead, polymeric damping brominated grafting agent-5 is added, with an addition amount of 28g. That is: first, nitrogen gas is purged five times in a 4L stainless steel reactor with a jacket, and then 350g of dichloromethane, 650g of pentane, and polymeric damping brominated grafting agent-5 are added to the polymerization reactor. 28g of methanol was added and stirred for 46 minutes until completely dissolved. Then, the temperature was lowered to -78℃, followed by the sequential addition of 950g of chloromethane, 500g of isobutylene, and 23g of isoprene. The mixture was stirred until the polymerization system temperature reached -88℃. Then, 95g of chloromethane, 1.75g ​​of sesquiethylaluminum chloride, and 0.063g of HCl were mixed and aged at -98℃ for 58 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.8 hours. Finally, 23g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0076] Comparative Example 7

[0077] (1) Preparation of polymeric damping brominated grafting agent: Other conditions are the same as in Example 6, except that: in the preparation of polymeric damping brominated grafting agent, allyl bromide is not added, but ethylene bromide is added, and the amount added is 340g. That is: first, in a 15L stainless steel reactor with a jacket, argon gas is purged 4 times, and 3900g pentane, 660g p-methylstyrene, and 5.7g THF are added to the polymerization reactor in sequence. The temperature is raised to 68°C, and 22.8mmol n-butyllithium is added to start the reaction for 77min; then 340g ethylene bromide and 3.7g THF are added to the polymerization reactor, and the temperature is raised to 88°C and the reaction is carried out for 118min; finally, 35g isoprene is added to the polymerization reactor and the end-capping reaction is carried out for 28min until no free monomers are present. The glue solution is wet coagulated and dried to obtain polymeric damping brominated grafting agent-6 (Mn is 31000, bromine content is 0.12%). The polymeric damping brominated grafting agent obtained in this comparative example, in the general formula I, I is isoprene; R1 is methyl (CH3); R2 is hydrogen atom (H); n is the number of repeating units: n≥1. (2) Preparation of high-damping brominated branched butyl rubber: Other conditions are the same as in Example 6, except that: no polymeric damping brominated grafting agent is added in the preparation process of high-damping brominated branched butyl rubber, but polymeric damping brominated grafting agent-6 is added, and the amount added is 28g, that is: firstly, in a 4L stainless steel reactor with a jacket, nitrogen gas is purged 5 times, and 350g of dichloromethane, 650g of pentane, and polymeric damping brominated grafting agent-6 are added to the polymerization reactor. 28g of methanol was added and stirred for 46 minutes until completely dissolved. Then, the temperature was lowered to -78℃, followed by the sequential addition of 950g of chloromethane, 500g of isobutylene, and 23g of isoprene. The mixture was stirred until the polymerization system temperature reached -88℃. Then, 95g of chloromethane, 1.75g ​​of sesquiethylaluminum chloride, and 0.063g of HCl were mixed and aged at -98℃ for 58 minutes, and then added to the polymerization system. The mixture was stirred and reacted for 2.8 hours. Finally, 23g of methanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain the high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0078] Comparative Example 8

[0079] (1) Preparation of polymeric damping brominated grafting agent: Same as in Example 7.

[0080] (2) Preparation of high-damping brominated branched butyl rubber: Other conditions are the same as in Example 7, except that the amount of polymeric damping brominated grafting agent added during the preparation of high-damping brominated branched butyl rubber is 12g. That is: first, in a 4L stainless steel reactor with a jacket, nitrogen gas is purged 5 times, and 300g of dichloromethane, 700g of pentane, and 12g of polymeric damping brominated grafting agent are added to the polymerization reactor. The mixture is stirred and dissolved for 50 minutes until completely dissolved. Then, when the temperature is lowered to -80℃, 1000g of monochloromethane, 500g of isobutylene, and 25g of isoprene are added sequentially. The mixture is stirred and mixed until the temperature of the polymerization system drops to -90℃. Then, 100g of monochloromethane, 1.75g ​​of sesquiethylaluminum chloride, and HCl are added. 0.085g of the mixture was aged at -100℃ for 60 minutes, then added to the polymerization system and stirred for 3.0 hours. Finally, 25g of ethanol was added, and the mixture was discharged, coagulated, washed, and dried to obtain a high-damping brominated branched butyl rubber product. Sampling and analysis: Standard samples were prepared, and the test performance is shown in Table 1.

[0081] Table 1 Properties of High Damping Brominated Branched Butyl Rubber

[0082]

Claims

1. A method for preparing a polymeric damping brominated grafting agent, characterized in that, include: Based on 100% of the total mass of the reactants, 300%–400% solvent, 50%–70% p-alkylstyrene, and 0.4%–0.6% structure modifier were added sequentially to the reactor. After heating to 60–70°C, an initiator was added and the reaction proceeded for 60–80 minutes. Next, 30%–50% allyl halide and 0.2%–0.4% structure modifier were added to the reactor, and the temperature was raised to 80–90°C, with the reaction proceeding for 100–120 minutes. Finally, 2–4 parts of isoprene were added to the reactor for end-capping, and the reaction proceeded for 20–30 minutes until no free monomers remained. The resulting solution was then wet-coagulated and dried to obtain a polymeric damping brominated grafting agent. The initiator is RLi, wherein R is a saturated aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group or a complex group of the above groups containing 1 to 20 carbon atoms; The polymeric damping brominated grafting agent has a number average molecular weight of 40,000 to 50,000 and a bromine content of 3 to 4% by mass.

2. The method according to claim 1, characterized in that, The initiator is selected from one of n-butyllithium, sec-butyllithium, methylbutyllithium, phenylbutyllithium, naphthalenelithium, cyclohexyllithium, and dodecyllithium.

3. The method according to claim 2, characterized in that, The initiator is n-butyllithium.

4. The method according to claim 2, characterized in that, The structure modifier is selected from one of diethylene glycol dimethyl ether, tetrahydrofuran, diethyl ether, ethyl methyl ether, anisole, diphenyl ether, ethylene glycol dimethyl ether, and triethylamine.

5. The method according to claim 4, characterized in that, The structure modifier is tetrahydrofuran.

6. The method according to claim 1, characterized in that, The p-alkylstyrene is one of p-methylstyrene, p-ethylstyrene, p-propylstyrene, p-n-butylstyrene, p-isobutylstyrene, and p-isopentylstyrene.

7. The method of claim 6, characterized in that, The p-alkylstyrene mentioned is p-methylstyrene.

8. The method according to claim 1, characterized in that, The allyl halide is one of allyl bromide, 2-methyl-1-allyl bromide, 2-ethyl-1-allyl bromide, 2-propyl-1-allyl bromide, and 2-butyl-1-allyl bromide.

9. The method of claim 8, characterized in that, The allyl halide mentioned is allyl bromide.

10. A method for preparing high-damping brominated branched butyl rubber, characterized in that, include: Add 100% to 200% of a mixed solvent (of 70% to 30% by mass of isobutylene, the mixed solvent being a diluent / solvent mixture) and 3% to 6% of the polymeric damping brominated grafting agent prepared by any of claims 1-9 to the reactor. Stir and dissolve for 30 to 50 minutes until the grafting agent is completely dissolved. Then, when the temperature is lowered to -80 to -70°C, add 100% to 200% of the diluent, 100% of isobutylene, and 3% to 5% of isoprene in sequence. Stir and mix until the polymerization system temperature drops to -90 to -80°C. Then, mix and age 10% to 20% of the diluent and 0.05% to 0.3% of the co-initiator at -100 to -90°C for 50 to 60 minutes, and then add them together to the polymerization system. Stir and react for 2.0 to 3.0 hours. Finally, add 3% to 6% of the diluent. After adding 5% terminator, the material is discharged, coagulated, washed, and dried to obtain a high-damping brominated branched butyl rubber product. The co-initiator is a combination of alkyl aluminum halide and protic acid.

11. The method of claim 10, characterized in that, The diluent is a haloalkane, wherein the halogen atom in the haloalkane is chlorine, bromine or fluorine; and the number of carbon atoms in the haloalkane is C1-C4.

12. The method of claim 11, characterized in that, The diluent is selected from one of the following: chloromethane, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloropropane, heptachloropropane, fluoromethane, difluoromethane, tetrafluoroethane, carbon hexafluoride, and fluorobutane.

13. The method of claim 12, characterized in that, The diluent is chloromethane.

14. The method of claim 10, characterized in that, The alkyl aluminum halide is selected from at least one of diethylaluminum chloride, diisobutylaluminum chloride, dichloromethylaluminum, sesquiethylaluminum chloride, sesquiisobutylaluminum chloride, dichloro-n-propylaluminum, dichloroisopropylaluminum, dimethylaluminum chloride, and ethylaluminum chloride; the protic acid is selected from one of HCl, HF, HBr, H2SO4, H2CO3, H3PO4, and HNO3.

15. The method of claim 14, characterized in that, The alkyl aluminum halide is sesquiethyl aluminum chloride, and the protic acid is HCl.

16. The method of claim 10, characterized in that, In the co-initiator, the molar ratio of protic acid to alkyl aluminum halide is 0.01:1 to 0.1:

1.

17. The method of claim 10, characterized in that, The terminator is selected from one or more of methanol, ethanol, and butanol.

18. The method of claim 10, characterized in that, The solvent is a hydrocarbon solvent selected from one of pentane, hexane, octane, heptane, cyclohexane, benzene, toluene, xylene, and ethylbenzene.

19. The method of claim 18, characterized in that, The solvent is pentane.

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