A method for preparing brominated highly branched butyl rubber

Abstract

The invention discloses a kind of preparation method of brominated highly branched butyl rubber, the preparation method includes adding quaternary three-arm brominated grafting agent to a mixed solvent, is sufficiently stirred until the quaternary three-arm brominated grafting agent is completely dissolved, and a mixed solution is obtained; Cooling, diluent, isobutylene and isoprene are sequentially added into the mixed solution, is sufficiently stirred and mixed, and a polymerization reaction system is obtained, and the temperature is again lowered; Diluent and co-initiator are mixed and aged, and then added to the polymerization reaction system and fully stirred and reacted after, terminator is added, discharging condenses, washes, dries, and brominated highly branched butyl rubber is obtained; Quaternary three-arm brominated grafting agent is a quaternary three-arm full primary position brominated star block copolymer consisting of isoprene, 1,3-butadiene, styrene and reactive brominating agent. The preparation method of the present invention enables butyl rubber to maintain enough green rubber strength and good air tightness, imparts the balance of physical and mechanical properties and vulcanization processability.

Description

Technical Field

[0001] The present invention relates to a method for preparing brominated highly branched butyl rubber, and in particular to a method for preparing brominated highly branched butyl rubber by grafting and modifying a quaternary three-arm star-shaped block copolymer of isoprene / butadiene / styrene / reactive brominating agent having a primary brominated structure. Background Art

[0002] Butyl rubber (IIR) is a cationic copolymer of isobutylene and a small amount of isoprene. It exhibits excellent air tightness, damping properties, heat aging resistance, ozone resistance, and weather resistance, making it widely used in the manufacture of inner tubes, airtight layers, and vulcanizing bladders for automotive tires, making it one of the most important synthetic rubbers. However, the butyl rubber molecular chain is primarily composed of carbon-carbon single bonds, has a low degree of unsaturation, and has symmetrically arranged methyl substituents. This leads to high crystallinity, poor molecular chain flexibility, slow stress release and vulcanization rates, poor adhesion, and poor compatibility with other general-purpose rubbers. Consequently, butyl rubber is prone to excessive flow and deformation during processing, which has become a bottleneck in the expansion of butyl rubber's application.

[0003] Currently, 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 action of molecular bromine. Compared to IIR, BIIR not only has the same excellent airtightness, but the introduction of bromine atoms not only increases the polarity of the molecular chain, improving adhesion to other rubbers, and can be used in any ratio with unsaturated rubbers such as natural rubber and styrene-butadiene rubber, but also creates additional crosslinking sites, enhancing the activity of the original double bonds, improving the vulcanization properties of the rubber, faster vulcanization speed, more diverse vulcanization methods, and increased heat resistance. Therefore, BIIR is gradually replacing IIR in industrial products such as radial tires, tubeless tires, medical sealing equipment, and chemical equipment linings, and has broad industrial application value and prospects.

[0004] In recent years, researchers have discovered a star-branched butyl rubber composed of high-molecular-weight branched structures and low-molecular-weight linear structures. This star-branched butyl rubber can be brominated to produce brominated star-branched butyl rubber. This brominated star-branched butyl rubber, due to its unique "three-dimensional network" branching structure and bromine atoms, possesses a wide molecular weight distribution and excellent viscoelastic properties, as well as high green strength and a fast cure rate. In particular, during processing, it exhibits low melt viscosity, low processing energy consumption, low binder removal temperature, low shrinkage, and long scorch time. This balance of physical and mechanical properties and processing performance is achieved in brominated star-branched butyl rubber. Therefore, brominated star-branched butyl rubber has become a hot topic in the future butyl rubber research.

[0005] CN112574333A provides a bromination process for star-branched butyl rubber, which comprises: a) dissolving the star-branched butyl rubber in an aliphatic hydrocarbon to obtain a rubber solution; b) mixing the above-mentioned rubber solution with a branching agent and a scavenger ethanol to obtain a mixed solution; c) adding an oxidizing agent, hydrogen peroxide, and a brominating agent, Br2, to the above-mentioned mixed solution, wherein the molar ratio of bromine element to unsaturated double bonds in the star-branched butyl rubber is Bromination reaction, final neutralization, and product recovery are performed to obtain brominated star-branched butyl rubber. This process can dissolve the residual branching agent in the star-branched butyl rubber before bromination, preventing it from combining with the HBr byproduct generated during the bromination process, thereby improving neutralization efficiency and inhibiting the isomerization transformation of Type II secondary structure to Type III primary structure.

[0006] CN112011019A discloses a method for preparing a halogenated bimodal star-branched butyl rubber. The method uses anionic polymerization technology to synthesize a poly(styrene-conjugated diene) block polymer, which is then coupled with silicon tetrachloride to obtain a four-arm star-shaped block polymer. After dissolving the copolymer, HCl gas is continuously introduced at -20 to 0°C for 3 to 12 hours to obtain a functionalized four-arm star-shaped branching agent containing silicon and chlorine. The functionalized four-arm star-shaped branching agent containing silicon and chlorine is dissolved in a solvent, isobutylene and isoprene are added, the temperature is lowered to below -60°C, a primary initiator and a co-initiator are mixed and aged, and then added to the system. The mixture is polymerized under stirring for 3 to 30 minutes, a terminator is added to terminate the reaction, the mixture is steamed under reduced pressure, and the sample is vacuum dried. The rubber is then halogenated to obtain a halogenated bimodal star-shaped branched butyl rubber. The bimodal star-shaped branched butyl rubber prepared by this method has the characteristics of low Mooney stress relaxation and lower intrinsic viscosity, and exhibits good processing properties.

[0007] CN 101353403B discloses a method for preparing star-branched polyisobutylene or butyl rubber. The method adopts a polystyrene / isoprene block copolymer containing a silyl chloride group at the end or a polystyrene / butadiene block copolymer containing a silyl chloride group at the end as an initiator-grafting agent for cationic polymerization. The method directly participates in cationic polymerization in a cationic polymerization system containing a mixed solvent of monochloromethane / cyclohexane with a v:v ratio of 20-80 / 80-20 at a temperature of 0-100°C. The star-branched polyisobutylene or butyl rubber product is prepared by the cationic polymerization initiated by the silyl chloride group and the grafting reaction of unsaturated chains.

[0008] CN 106749816A discloses a method for preparing brominated butyl rubber. The method first dissolves the butyl rubber in n-alkanes, then uses a specific organic bromide, such as phenyltrimethylammonium tribromide, benzyltrimethylammonium tribromide, or dibromoisocyanuric acid, as a brominating agent, and Br2 or HBr as a bromination accelerator in a solvent to carry out a bromination reaction to obtain brominated butyl rubber. This method inhibits the molecular rearrangement of secondary bromine in the brominated butyl rubber to form tertiary bromine, thereby increasing the content of secondary bromine structures in the brominated butyl rubber.

[0009] Wu Yibo et al. (Davang SH, et al. Skid resistant coatings for aircraft carrier decks [J]. Coat Technol, 1980, 52 (671): 65-69.) disclosed a method of preparing a poly (isoprene-styrene) block copolymer as a grafting agent by living anionic polymerization, and preparing a star-branched butyl rubber showing obvious bimodal properties by living carbocationic polymerization in an initiation system of 2-chloro-2,4,4-trimethylpentane / titanium tetrachloride / proton scavenger.

[0010] Synthetic Rubber Industry (2006, 29(4): A method for preparing brominated butyl rubber (Polysar-301) by dissolving it in cycloalkanes and brominating it with liquid bromine was disclosed. The effects of residence time and reaction temperature on the Mooney viscosity, unsaturation, bromine content, and microstructure of the product were investigated. The results showed that the Mooney viscosity and unsaturation decreased sharply when the residence time was less than 2 minutes, but remained largely unchanged after 2 minutes. Increasing the reaction temperature decreased the Mooney viscosity while having little effect on the unsaturation. Increasing the reaction temperature and residence time not only increased the bromine content of the product but also promoted a rearrangement of its molecular structure, namely, a shift from a secondary allylic bromide configuration to a more stable primary allylic bromide configuration.

[0011] In the above-mentioned prior art, the brominated butyl rubber obtained by dissolving and brominating star-branched butyl rubber or butyl rubber exhibits a larger molecular weight distribution, increased stress relaxation rate, faster vulcanization speed, and excellent processability. However, these methods still have certain limitations. During the bromination of butyl rubber, hydrogen bromide is easily generated as a byproduct, resulting in loss of the remaining bromine, reducing bromine utilization and significantly isomerizing the Type II secondary structure of the brominated butyl rubber to the Type III primary structure, thereby affecting the processability of the brominated butyl rubber. Furthermore, hydrogen bromide is highly corrosive, resulting in deterioration of the quality of the brominated butyl rubber and potentially causing environmental pollution and human health issues. Summary of the Invention

[0012] The present invention provides a method for preparing brominated hyperbranched butyl rubber. This method uses alkyl lithium as an initiator, a hydrocarbon as a solvent, and reactive monomers consisting of isoprene, styrene, butadiene, and a reactive brominating agent. These monomers are added sequentially into a polymerization system four times to synthesize linear and multi-double-bond long-chain segments. Subsequently, the copolymer is coupled with a coupling agent to produce a quaternary three-arm brominated star copolymer. This quaternary three-arm brominated star copolymer serves as a grafting agent and is then cationic polymerized with isobutylene and isoprene to produce the hyperbranched butyl rubber. This method avoids rearrangement of the bromine structure while ensuring sufficient green strength and good air tightness in the brominated hyperbranched butyl rubber. This method addresses the low vulcanization efficiency and slow stress relaxation rate that are common problems with butyl rubber during processing, resulting in the brominated hyperbranched butyl rubber having good processability and achieving a balance between the physical and mechanical properties and processing performance of the hyperbranched butyl rubber.

[0013] Unless otherwise specified, the "%" mentioned in the present invention refers to mass percentage.

[0014] To achieve the above object, the present invention provides a method for preparing brominated highly branched butyl rubber, the preparation method comprising the following steps:

[0015] S1: adding a quaternary three-arm brominated grafting agent to a mixed solvent and stirring thoroughly until the quaternary three-arm brominated grafting agent is completely dissolved to obtain a mixed solution;

[0016] S2: Cooling the mixture, sequentially adding a diluent, isobutylene, and isoprene to the mixed solution of step S1, stirring and mixing the mixture to obtain a polymerization reaction system, and cooling the mixture again;

[0017] S3: mixing the diluent and the co-initiator and aging them, then adding them to the polymerization reaction system of step S2, stirring them thoroughly for reaction, adding a terminator, coagulating the discharged material, washing, and drying it to obtain brominated highly branched butyl rubber;

[0018] It is characterized in that the quaternary three-arm brominated grafting agent is a quaternary three-arm all-primary brominated star block copolymer composed of isoprene, 1,3-butadiene, styrene and a reactive brominating agent, and its general structural formula is shown in Formula I:

[0019]

[0020] Among them, Bu is tert-butyl; IR is an isoprene homopolymer block; BR is a 1,3-butadiene homopolymer segment; SBR is a styrene-butadiene random block copolymer; m is the number of repeating units, and m is an integer ≥1; the number average molecular weight (Mn) of the quaternary three-arm brominated grafting agent is 80,000 to 100,000, and the molecular weight distribution (Mw / Mn) is 9.13 to 11.05.

[0021] In the method for preparing brominated highly branched butyl rubber of the present invention, in step S1, the mass ratio of the mixed solvent to the quaternary three-arm brominated grafting agent is 100-200:7-12.

[0022] In the method for preparing brominated highly branched butyl rubber of the present invention, in step S1, the mixed solvent comprises a diluent and a solvent, and the volume ratio of the diluent to the solvent is 70-30 / 30-70.

[0023] In the method for preparing brominated highly branched butyl rubber of the present invention, in step S2, the temperature is lowered to -80 to -90°C.

[0024] In the method for preparing brominated highly branched butyl rubber of the present invention, in step S2, the mass ratio of the diluent, isobutylene and isoprene is 100-200:80-90:3-8.

[0025] In the method for preparing brominated highly branched butyl rubber of the present invention, in step S2, the temperature is lowered again to a temperature of -100 to -90°C.

[0026] In the method for preparing brominated highly branched butyl rubber of the present invention, in step S3, the mass ratio of the diluent, the co-initiator and the terminator is 20-30:0.3-0.7:5-10.

[0027] In the preparation method of brominated highly branched butyl rubber of the present invention, in step S3, the aging temperature is -95°C to -85°C, and the aging time is 30 to 50 minutes.

[0028] The preparation method of the brominated highly branched butyl rubber of the present invention specifically comprises the following steps:

[0029] Based on 100 parts by weight of the reactive brominating agent, 300 wt% to 400 wt% of solvent, 60 wt% to 80 wt% of isoprene, and 0.1 wt% to 0.4 wt% of a structure regulator are first added sequentially to a reactor after inert gas replacement, the temperature is raised to 40 to 50° C., an initiator is added, and the reaction is carried out for 50 to 70 minutes to form an -IR- segment; then 40 wt% to 60 wt% of 1,3-butadiene and 0.05 wt% to 0.2 wt% of a structure regulator are added sequentially to reactor A, the temperature is raised to 60 to 70° C., and the reaction is carried out for 40 to 60 minutes to form an -IR-BR- segment; then, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 39, 43, 30, 31, 32, 34, 35, 37, 38, 39, 40, 42, 31, 32, 33, 34, 35, 36 ... 30 wt% to 50 wt% of styrene, 50 wt% to 60 wt% of 1,3-butadiene, and 0.2 to 0.5 wt% of a structure regulator are added, the temperature is raised to 70 to 80° C., and the reaction is carried out for 60 to 80 minutes to form -IR-BR--SBR- segments. Then, 100 wt% of a reactive brominating agent and an initiator are added to the reactor A, and the reaction is carried out for 80 to 90 minutes until no free monomers are present. Finally, the reactor A is heated to 80 to 90° C., a coupling agent is added to carry out a coupling reaction, and the reaction mixture after the reaction is treated with water after 90 to 120 minutes. The reaction mixture is subjected to wet coagulation and drying to obtain a quaternary three-arm brominated grafting agent.

[0030] The initiator in the method for preparing brominated highly branched butyl rubber of the present invention is a hydrocarbon monolithium compound, namely, RLi, where R is a saturated aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group, or a composite of the foregoing groups containing 1 to 20 carbon atoms. The hydrocarbon monolithium compound is selected from at least one of n-butyllithium, sec-butyllithium, methylbutyllithium, phenylbutyllithium, naphthalenelithium, cyclohexyllithium, and dodecyllithium, preferably n-butyllithium. The amount of initiator added is determined by the molecular weight of the designed polymer.

[0031] The method for preparing brominated highly branched butyl rubber of the present invention comprises a polar organic compound as the structure regulator, which produces a solvation effect in the polymerization system and can adjust the reactivity ratio of styrene and isoprene, thereby causing the two to copolymerize randomly. The polar organic compound is selected from at least one of diethylene glycol dimethyl ether (DGE), tetrahydrofuran (THF), ethyl ether, ethyl methyl ether, anisole, diphenyl ether, ethylene glycol dimethyl ether (DME), and triethylamine, preferably tetrahydrofuran (THF).

[0032] In the preparation method of brominated highly branched butyl rubber of the present invention, the reactive brominating agent is selected from at least one of p-bromomethylstyrene and p-chloromethylstyrene, preferably p-bromomethylstyrene.

[0033] In the method for preparing brominated highly branched butyl rubber of the present invention, the coupling agent is a halosilane coupling agent selected from tert-butyltrichlorosilane and tert-butyltribromosilane, preferably tert-butyltrichlorosilane. The amount of the coupling agent used depends on the amount of the initiator, and the molar ratio of the coupling agent to the initiator is 2:1 to 6:1.

[0034] The polymerization reaction in the method for preparing brominated highly branched butyl rubber of the present invention is carried out in an oxygen-free and water-free environment, preferably in an inert gas environment. The polymerization reaction and dissolution process are both carried out in a hydrocarbon solvent. The solvent of the present invention is a hydrocarbon solvent, which includes linear alkanes, aromatic hydrocarbons, and cycloalkanes. The hydrocarbon solvent is selected from at least one of pentane, hexane, octane, heptane, cyclohexane, benzene, toluene, xylene, and ethylbenzene, with hexane being preferred.

[0035] In the method for preparing brominated highly branched butyl rubber of the present invention, the diluent is a halogenated alkane, wherein the halogen atoms in the halogenated alkane may be chlorine, bromine, or fluorine; and the number of carbon atoms in the halogenated alkane is C1-C4. The halogenated alkane is at least one selected from the group consisting of monochloromethane, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloropropane, heptachloropropane, monofluoromethane, difluoromethane, tetrafluoroethane, carbon hexafluoride, and fluorobutane, with monochloromethane being preferred.

[0036] The present invention provides a method for preparing brominated highly branched butyl rubber. The co-initiator comprises an alkyl aluminum halide and a protonic acid compounded in different proportions. The alkyl aluminum halide is selected from at least one of diethylaluminum monochloride, diisobutylaluminum monochloride, methylaluminum dichloride, sesquiethylaluminum chloride, sesquiisobutylaluminum chloride, n-propylaluminum dichloride, isopropylaluminum dichloride, dimethylaluminum chloride, and ethylaluminum chloride, preferably sesquiethylaluminum chloride. The protonic acid is selected from at least one of HCl, HF, HBr, H2SO4, H2CO3, H3PO4, and HNO3, preferably HCl. The molar ratio of the protonic acid to the alkyl aluminum halide is 0.07:1 to 0.6:1.

[0037] In the preparation method of brominated highly branched butyl rubber of the present invention, the terminator is, for example but not limited to, at least one of methanol, ethanol, and butanol.

[0038] The present invention can also be described in detail as follows:

[0039] In detail, the specific preparation process of the preparation method of the brominated highly branched butyl rubber of the present invention comprises the following steps:

[0040] (1) Preparation of quaternary three-arm brominated grafting agent: Based on 100% of the mass of the brominating agent, first, in a 15L stainless steel reactor A with a jacket, argon gas was replaced 2 to 4 times, and 300 wt% to 400 wt% of solvent, 60 wt% to 80 wt% of isoprene, and 0.1 wt% to 0.4 wt% of structure regulator were added to the reactor A in sequence, and the temperature was raised to 40 to 50°C. An initiator was added and the reaction was carried out for 50 to 70 minutes to form -IR- segments; then 40 wt% to 60 wt% of 1,3-butadiene and 0.05 wt% to 0.2 wt% of structure regulator were added to the reactor A in sequence, and the temperature was raised to 60 to 70°C. The reaction was carried out for 40 to 60 minutes to form -IR- segments. BR-chain segment; then, 30wt%-50wt% of styrene and 50wt%-60wt% of 1,3-butadiene, and 0.2-0.5wt% of a structure regulator are sequentially added to the reactor A, the temperature is raised to 70-80°C, and the reaction is carried out for 60-80min to form -IR-BR--SBR-chain segment; then, 100wt% of a reactive brominating agent and an initiator are added to the reactor A, and the reaction is carried out for 80-90min until no free monomer is present; finally, the reactor A is heated to 80-90°C, a coupling agent is added to carry out a coupling reaction, and the reaction mixture after 90-120min is treated with water, and the reaction mixture is subjected to wet coagulation and drying to obtain a quaternary three-arm brominated grafting agent.

[0041] (2) Preparation of brominated highly branched butyl rubber: Based on 100% of the total mass of the reaction monomers, first, in a 4L stainless steel reactor with a jacket, nitrogen is replaced 3 to 5 times, 100wt% to 200wt% of a mixed solvent (diluent / solvent V:V ratio is 70 to 30 / 30 to 70) and 7wt% to 12wt% of a quaternary three-arm brominated grafting agent are added to the reactor, and stirred and dissolved for 80 to 100 minutes until the grafting agent is completely dissolved; then, when the temperature is lowered to -80 to -90°C, 100wt% to 200wt% of a diluent and 12wt% of a quaternary three-arm brominated grafting agent are added in sequence. The invention discloses a method for preparing a brominated highly branched butyl rubber product comprising the steps of: preparing a dispersant, 80 wt% to 90 wt% isobutylene, and 3 wt% to 8 wt% isoprene, and stirring and mixing the mixture until the temperature of the polymerization system drops to -100 to -95°C; then, mixing and aging 20 wt% to 30 wt% of a diluent and 0.3 wt% to 0.7 wt% of a co-initiator at -95 to -85°C for 30 to 50 minutes, and then adding the mixture to the polymerization system, stirring and reacting for 3.0 to 5.0 hours; finally, adding 5 wt% to 10 wt% of a terminator, and discharging the product for coagulation, washing, and drying to obtain a brominated highly branched butyl rubber product.

[0042] The quaternary three-arm brominated grafting agent of the present invention is a quaternary three-arm all-primary brominated star block copolymer composed of isoprene, 1,3-butadiene, styrene and a reactive brominating agent, and its general structural formula is shown in Formula I:

[0043]

[0044] Wherein, Bu represents a tert-butyl group; IR represents an isoprene homopolymer block; BR represents a 1,3-butadiene homopolymer segment; SBR represents a styrene-butadiene random block copolymer; and m represents the number of repeating units. The quaternary three-arm brominated grafting agent has a number average molecular weight (Mn) of 80,000 to 100,000 and a molecular weight distribution (Mw / Mn) of 9.13 to 11.05.

[0045] The invention first uses alkyl lithium as an initiator, hydrocarbons as a solvent, and an organic matter with a certain polarity as a structure regulator. Reaction monomers consist of isoprene, styrene, butadiene, and a reactive brominating agent. The monomers are added in sequence four times and then coupled with a trihalosilane coupling agent to prepare a quaternary three-arm brominated grafting agent having a three-arm structure and a primary bromine structure. Finally, the quaternary three-arm brominated grafting agent is reacted with isobutylene and isoprene in a catalytic system of a composite of alkyl aluminum halide and protonic acid to prepare brominated highly branched butyl rubber through cationic polymerization.

[0046] The present invention combines four chain segments with different microstructures on a macromolecular chain to form a quaternary three-arm star structure and a primary bromine structure, so that the performance of the different chain segments, the characteristics of the quaternary three-arm structure and the primary bromine structure can be organically combined and work synergistically.

[0047] First, this primary bromine structure is introduced into the main chain of butyl rubber through a grafting process, which solves the problem of butyl rubber being difficult to vulcanize due to the small number of unsaturated double bonds, accelerates the vulcanization speed, increases the degree of vulcanization, and improves the vulcanization efficiency.

[0048] Secondly, the vinyl groups in the BR, IR and SBR chain segments can undergo cationic polymerization with isobutylene, forming multiple connections on the main chain during the grafting process of butyl rubber to form highly branched butyl rubber. This high branching and quaternary three-arm structure characteristics increase the disorder of the molecular chain segments during the grafting polymerization of butyl rubber, significantly destroy the regularity of the molecular chain, and significantly broaden the molecular weight distribution, allowing butyl rubber to obtain good viscoelastic properties and a fast stress relaxation rate, thereby improving the processing performance of butyl rubber.

[0049] Finally, the -SBR- segment and primary bromine structure in the quaternary three-arm brominated grafting agent contain a certain amount of benzene rings. The benzene rings have the characteristics of high rigidity and large steric hindrance, which can avoid the decrease in strength and air tightness caused by the increase in the branching degree of butyl rubber, ensuring that the butyl rubber has sufficient strength and good air tightness. The present invention achieves a balance between the vulcanization characteristics, processability, strength and air tightness of butyl rubber, so that the performance of butyl rubber is more comprehensively improved. The preparation method of brominated highly branched butyl rubber provided by the present invention has the characteristics of short process flow, controllable bromine structure, safety and environmental protection, and suitability for industrial production.

[0050] In summary, the present invention has the following beneficial effects:

[0051] 1. The quaternary three-arm brominated grafting agent of the present invention adopts anionic polymerization rather than the ion substitution reaction in the prior art, thereby avoiding the rearrangement of the bromine structure, improving the stability of the all-primary bromine structure in the brominated highly branched butyl rubber, and solving the problem of butyl rubber being difficult to vulcanize due to the small number of unsaturated double bonds. It accelerates the vulcanization speed, increases the degree of vulcanization, and improves the vulcanization efficiency.

[0052] 2. The quaternary three-arm brominated grafting agent of the present invention uses a reactive brominating agent with anionic reaction characteristics to carry out anionic polymerization. No by-product HBr is generated during the entire reaction process, thereby improving the utilization rate of the bromine element in the brominated highly branched butyl rubber.

[0053] 3. The quaternary three-arm brominated grafting agent of the present invention does not generate the byproduct HBr during the entire reaction process, reducing the harm to humans and the environment, eliminating the alkali washing and recovery process of the byproduct HBr, thereby shortening the process and reducing production costs.

[0054] 4. The quaternary three-arm brominated grafting agent of the present invention utilizes the vinyl groups in the BR, IR, and SBR segments to undergo cationic polymerization with isobutylene. During the grafting process of the butyl rubber, multiple connections are formed on the main chain to form highly branched butyl rubber. This structural feature increases the disorder of the molecular segments of the butyl rubber, significantly destroys the regularity of the molecular chains, and significantly broadens the molecular weight distribution. The butyl rubber can obtain good viscoelastic properties and a fast stress relaxation rate, thereby improving the processing performance of the butyl rubber. In addition, the benzene ring structure contained in the SBR segment and the reactive brominating agent can avoid the decrease in strength and air tightness caused by the broadening of the molecular weight distribution of the butyl rubber, thereby ensuring that the butyl rubber has high strength and good air tightness, and achieving a balance between the vulcanization characteristics and processability of the butyl rubber and the strength and air tightness.

[0055] 5. The quaternary three-arm brominated grafting agent of the present invention is a new type of safe and environmentally friendly compound that does not emit atmospheric pollutants (VOC) and by-product HBr. Its preparation method is green and environmentally friendly, the process flow is short, the bromine structure is stable, the processing performance is excellent, and it is suitable for industrial production. DETAILED DESCRIPTION

[0056] The following is a detailed description of the embodiments of the present invention: This embodiment is implemented based on the technical solution of the present invention, and provides detailed implementation methods and processes. However, the protection scope of the present invention is not limited to the following embodiments. The experimental methods in the following embodiments where specific conditions are not specified are generally based on conventional conditions.

[0057] (1) Source of raw materials:

[0058] Styrene, 1,3-butadiene, polymer grade, PetroChina Lanzhou Petrochemical Company;

[0059] Isobutylene, isoprene, polymer grade Zhejiang Xinhui New Materials Co., Ltd.;

[0060] p-Bromomethylstyrene, polymer grade Shanghai Yien Chemical Technology Co., Ltd.;

[0061] n-Butyl lithium, 98% purity, Nanjing Tonglian Chemical Co., Ltd.;

[0062] Tert-butyltrichlorosilane, purity 98%, Nanjing Tonglian Chemical Co., Ltd.;

[0063] Ethyl aluminum chloride, purity 98%, J&K Technology Co., Ltd.;

[0064] Other reagents are commercially available products.

[0065] (2) Analytical testing methods:

[0066] Bromine content determination: Weigh 10 mg of sample and thermally degrade the sample using a Q600 TG / DTG thermogravimetric analyzer at a heating rate of 10°C / min in a nitrogen atmosphere at a flow rate of 50 mL / min. The first stage of thermal degradation is 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:

[0067]

[0068] Where: Y is the percentage of the sample at 220°C; 79.904 is the relative atomic mass of bromine; 1.008 is the relative atomic mass of hydrogen.

[0069] Molecular weight and distribution were determined using a 2414 gel permeation chromatograph (GPC) produced by Waters, USA. Polystyrene standards were used as the calibration curve, the mobile phase was tetrahydrofuran, the column temperature was 40°C, 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 .

[0070] Mooney stress relaxation was determined using a GT-7080S2 Mooney viscometer, using a large rotor at 125°C (1+8°C) according to the method described in GB / T 1232.1-2000. Stress relaxation was determined by rapidly stopping the rotor (within 0.1 second) after the Mooney viscosity test and recording the Mooney viscosity decay over time. The torque within 0.1 second of rotor cessation was set as 100%, and the stress relaxation behavior of the rubber was expressed as t80 (the time it takes for the torque to decay by 80% (remaining 20%)) and X30 (the percentage of torque remaining 30 seconds after the rotor stopped).

[0071] Characterization of the degree of branching: Degree of branching = molecular weight of polymer after branching / molecular weight of polymer before branching.

[0072] Vulcanization characteristics: tested according to GB / T 16584-1996.

[0073] Air tightness test: Use an automated air tightness tester to measure the air permeability according to ISO 2782:1995.

[0074] The test gas is N2, the test temperature is 23°C, and the test sample is a circular sea piece with a diameter of 8 cm and a thickness of 1 mm.

[0075] Tensile strength: Execute the method in standard GB / T528-2009.

[0076] Example 1

[0077] (1) Preparation of quaternary three-arm brominated grafting agent: First, in a 15L stainless steel reactor A with a jacket, argon was replaced twice, and 3000g hexane, 600g isoprene, and 1g THF were added to the reactor in sequence. The temperature was raised to 40°C, and 30.2mmol n-butyl lithium was added to start the reaction for 50min to form -IR- segment; then 400g 1,3-butadiene and 0.5g THF were added to the reactor A in sequence, and the temperature was raised to 60°C and the reaction was carried out for 40min to form -IR-BR- segment; then 300g styrene and 500g 1,3-butadiene, 2.0g THF, heated to 70 ° C, reacted for 60 minutes to form -IR-BR--SBR- segments, and then added 1000g of p-bromomethylstyrene and 10.5mmol of n-butyllithium to reactor A and reacted for 80 minutes until no free monomers existed; finally, the reactor A was heated to 80 ° C, and 90.5mmol of tert-butyltrichlorosilane was added to carry out coupling reaction. After reacting for 90 minutes, the coupled reaction mixture was treated with water, and the glue was wet coagulated and dried to obtain a quaternary three-arm brominated grafting agent (Mn is 81000, Mw / Mn is 9.13).

[0078] (2) Preparation of brominated hyperbranched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged three times. 150g of dichloromethane, 350g of hexane, and 35.0g of a quaternary three-arm brominated grafting agent were added to the reactor and stirred and dissolved for 80 minutes until completely dissolved. Then, when the temperature was cooled to -80°C, 500g of dichloromethane, 450g of isobutylene, and 15.0g of isoprene were added in sequence and stirred and mixed until the polymerization system temperature dropped to -90°C. Then, 100g of dichloromethane, 1.65g of sesquiethylaluminum chloride, and 0.031g of HCl were mixed and aged at -85°C for 30 minutes. The mixture was then added to the polymerization system and stirred for reaction for 3.0 hours. Finally, 25g of butanol was added. The product was discharged, condensed, washed, and dried to obtain a brominated hyperbranched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0079] Example 2

[0080] (1) Preparation of quaternary three-arm brominated grafting agent: First, in a 15L stainless steel reactor A with a jacket, argon was replaced twice, and 3100g hexane, 630g isoprene, and 1.5g THF were added to the reactor in sequence, and the temperature was raised to 42°C. 35.5mmol n-butyl lithium was added to start the reaction for 53min to form -IR- segment; then 420g 1,3-butadiene and 0.8g THF were added to the reactor A in sequence, and the temperature was raised to 62°C. The reaction was carried out for 43min to form -IR-BR- segment; then 320g styrene and 510g 1,3-butadiene, 2.5g THF, heated to 71 ° C, reacted for 63 minutes to form -IR-BR--SBR- segments, and then added 1000g of p-bromomethylstyrene and 11.5mmol of n-butyllithium to reactor A and reacted for 82 minutes until no free monomers were present; finally, the reactor A was heated to 81 ° C, and 100.2mmol of tert-butyltrichlorosilane was added for coupling reaction. After reacting for 95 minutes, the coupled reaction mixture was treated with water, and the glue was wet coagulated and dried to obtain a quaternary three-arm brominated grafting agent (Mn is 84000, Mw / Mn is 9.52).

[0081] (2) Preparation of brominated hyperbranched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged three times. 200g of dichloromethane, 300g of hexane, and 40.0g of a quaternary three-arm brominated grafting agent were added to the reactor and stirred for 84 minutes until completely dissolved. Then, when the temperature was cooled to -82°C, 600g of dichloromethane, 440g of isobutylene, and 20.0g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -92°C. Then, 110g of dichloromethane, 1.86g of sesquiethylaluminum chloride, and 0.045g of HCl were mixed and aged at -87°C for 33 minutes. The mixture was then added to the polymerization system and stirred for 3.4 hours. Finally, 30g of butanol was added. The product was discharged, condensed, washed, and dried to obtain a brominated hyperbranched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0082] Example 3

[0083] (1) Preparation of quaternary three-arm brominated grafting agent: First, in a 15L stainless steel reactor A with a jacket, argon was replaced three times, and 3300g hexane, 660g isoprene, and 2.0g THF were added to the reactor in sequence, and the temperature was raised to 44°C. 39.5mmol n-butyl lithium was added to start the reaction for 57min to form -IR- segment; then 480g 1,3-butadiene and 1.0g THF were added to the reactor A in sequence, and the temperature was raised to 64°C and the reaction was carried out for 48min to form -IR-BR- segment; then 350g styrene and 530g 1,3-butadiene, 3.0g THF, heated to 73 ° C, reacted for 66 minutes to form -IR-BR--SBR- segments, and then added 1000g of p-bromomethylstyrene and 12.5mmol of n-butyllithium to reactor A and reacted for 84 minutes until no free monomers were present; finally, the reactor A was heated to 83 ° C, and 120.2mmol of tert-butyltrichlorosilane was added for coupling reaction. After reacting for 100 minutes, the coupled reaction mixture was treated with water, and the glue was wet coagulated and dried to obtain a quaternary three-arm brominated grafting agent (Mn is 89000, Mw / Mn is 10.23).

[0084] (2) Preparation of brominated hyperbranched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged four times. 350g of dichloromethane, 150g of hexane, and 45.0g of a quaternary three-arm brominated grafting agent were added to the reactor and stirred and dissolved for 88 minutes until completely dissolved. Then, when the temperature was cooled to -84°C, 700g of dichloromethane, 430g of isobutylene, and 25.0g of isoprene were added in sequence and stirred and mixed until the polymerization system temperature dropped to -94°C. Then, 120g of dichloromethane, 2.06g of sesquiethylaluminum chloride, and 0.058g of HCl were mixed and aged at -89°C for 38 minutes. The mixture was then added to the polymerization system and stirred for reaction for 3.7 hours. Finally, 34g of butanol was added. The product was discharged, condensed, washed, and dried to obtain a brominated hyperbranched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0085] Example 4

[0086] (1) Preparation of quaternary three-arm brominated grafting agent: First, in a 15L stainless steel reactor A with a jacket, argon was replaced three times, and 3500g hexane, 700g isoprene, and 2.5g THF were added to the reactor in sequence, and the temperature was raised to 45°C. 41.2mmol n-butyl lithium was added to start the reaction for 60min to form -IR- segment; then 500g 1,3-butadiene and 1.3g THF were added to the reactor A in sequence, and the temperature was raised to 65°C and the reaction was carried out for 50min to form -IR-BR- segment; then 400g styrene and 550g 1,3-butadiene, 3.5g THF, heated to 74 ° C, reacted for 70 minutes to form -IR-BR--SBR- segments, and then added 1000g of p-bromomethylstyrene and 12.8mmol of n-butyllithium to reactor A and reacted for 85 minutes until no free monomers were present; finally, the reactor A was heated to 85 ° C, and 140.2mmol of tert-butyltrichlorosilane was added for coupling reaction. After reacting for 105 minutes, the coupled reaction mixture was treated with water, and the glue was wet coagulated and dried to obtain a quaternary three-arm brominated grafting agent (Mn is 92000, Mw / Mn is 10.46).

[0087] (2) Preparation of brominated hyperbranched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged four times. 560g of dichloromethane, 240g of hexane, and 50.0g of a quaternary three-arm brominated grafting agent were added to the reactor and stirred and dissolved for 90 minutes until completely dissolved. Then, when the temperature was cooled to -85°C, 800g of dichloromethane, 420g of isobutylene, and 30.0g of isoprene were added in sequence and stirred and mixed until the polymerization system temperature dropped to -95°C. Then, 130g of dichloromethane, 2.46g of sesquiethylaluminum chloride, and 0.062g of HCl were mixed and aged at -90°C for 41 minutes. The mixture was then added to the polymerization system and stirred and reacted for 4.0 hours. Finally, 40g of butanol was added. The product was discharged, condensed, washed, and dried to obtain a brominated hyperbranched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0088] Example 5

[0089] (1) Preparation of quaternary three-arm brominated grafting agent: First, in a 15L stainless steel reactor A with a jacket, argon was replaced 4 times, and 3600g hexane, 740g isoprene, and 3.0g THF were added to the reactor in sequence, and the temperature was raised to 47°C. 45.2mmol n-butyl lithium was added to start the reaction for 64min to form -IR- segment; then 530g 1,3-butadiene and 1.5g THF were added to the reactor A in sequence, and the temperature was raised to 67°C and the reaction was carried out for 54min to form -IR-BR- segment; then 430g styrene and 560g 1,3-butadiene, 4.0g THF, heated to 76 ° C, reacted for 72 minutes to form -IR-BR--SBR- segments, and then added 1000g of p-bromomethylstyrene and 13.1mmol of n-butyllithium to reactor A and reacted for 86 minutes until no free monomers were present; finally, the reactor A was heated to 87 ° C, and 160.3mmol of tert-butyltrichlorosilane was added for coupling reaction. After reacting for 110 minutes, the coupled reaction mixture was treated with water, and the glue was wet coagulated and dried to obtain a quaternary three-arm brominated grafting agent (Mn is 94000, Mw / Mn is 10.61).

[0090] (2) Preparation of brominated hyperbranched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged four times. 500g of dichloromethane, 300g of hexane, and 55.0g of a quaternary three-arm brominated grafting agent were added to the reactor and stirred for 93 minutes until completely dissolved. Then, when the temperature was cooled to -87°C, 900g of dichloromethane, 410g of isobutylene, and 35.0g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -97°C. Then, 140g of dichloromethane, 2.83g of sesquiethylaluminum chloride, and 0.071g of HCl were mixed and aged at -92°C for 45 minutes. The mixture was then added to the polymerization system and stirred for 4.3 hours. Finally, 43g of butanol was added. The product was discharged, condensed, washed, and dried to obtain a brominated hyperbranched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0091] Example 6

[0092] (1) Preparation of quaternary three-arm brominated grafting agent: First, in a 15L stainless steel reactor A with a jacket, argon was replaced 4 times, and 3800g hexane, 780g isoprene, and 3.5g THF were added to the reactor in sequence, and the temperature was raised to 48°C. 47.5mmol n-butyl lithium was added to start the reaction for 67min to form -IR- segment; then 560g 1,3-butadiene and 1.8g THF were added to the reactor A in sequence, and the temperature was raised to 68°C and the reaction was carried out for 58min to form -IR-BR- segment; then 460g styrene and 580g 1,3-butadiene, 4.5g THF, heated to 77 ° C, reacted for 75 minutes to form -IR-BR--SBR- segments, and then added 1000g of p-bromomethylstyrene and 13.5mmol of n-butyllithium to reactor A and reacted for 88 minutes until no free monomers were present; finally, the reactor A was heated to 89 ° C, 200.3mmol of tert-butyltrichlorosilane was added for coupling reaction, and after reacting for 115 minutes, the coupled reaction mixture was treated with water, and the glue was wet coagulated and dried to obtain a quaternary three-arm brominated grafting agent (Mn is 96000, Mw / Mn is 10.92).

[0093] (2) Preparation of brominated hyperbranched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged four times. 400g of dichloromethane, 400g of hexane, and 57.0g of a quaternary three-arm brominated grafting agent were added to the reactor and stirred for 95 minutes until completely dissolved. Then, when the temperature was lowered to -88°C, 950g of dichloromethane, 405g of isobutylene, and 38.0g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -98°C. Then, 145g of dichloromethane, 3.13g of sesquiethylaluminum chloride, and 0.085g of HCl were mixed and aged at -94°C for 48 minutes. The mixture was then added to the polymerization system and stirred for 4.6 hours. Finally, 45g of butanol was added. The product was discharged, condensed, washed, and dried to obtain a brominated hyperbranched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0094] Example 7

[0095] (1) Preparation of quaternary three-arm brominated grafting agent: First, in a 15L stainless steel reactor A with a jacket, argon was replaced 4 times, and 4000g hexane, 800g isoprene, and 4.0g THF were added to the reactor in sequence, and the temperature was raised to 50°C. 50.5mmol n-butyl lithium was added to start the reaction for 70min to form -IR- segment; then 600g 1,3-butadiene and 2.0g THF were added to the reactor A in sequence, and the temperature was raised to 70°C and the reaction was carried out for 60min to form -IR-BR- segment; then 500g styrene and 600g 1,3-butadiene, 5.0g THF, heated to 80°C, reacted for 80 minutes to form -IR-BR--SBR- segments, and then added 1000g of p-bromomethylstyrene and 14.1mmol of n-butyllithium to reactor A and reacted for 90 minutes until no free monomers existed; finally, the reactor A was heated to 90°C, 260.5mmol of tert-butyltrichlorosilane was added for coupling reaction, and after reacting for 120 minutes, the coupled reaction mixture was treated with water, and the glue was wet-coagulated and dried to obtain a quaternary three-arm brominated grafting agent (Mn is 99000, Mw / Mn is 11.05).

[0096] (2) Preparation of brominated hyperbranched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged five times. 700g of dichloromethane, 300g of hexane, and 60.0g of a quaternary three-arm brominated grafting agent were added to the reactor and stirred for 100 minutes until completely dissolved. Then, when the temperature was lowered to -90°C, 1000g of dichloromethane, 400g of isobutylene, and 40.0g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -98°C. Then, 150g of dichloromethane, 3.35g of sesquiethylaluminum chloride, and 0.096g of HCl were mixed and aged at -95°C for 50 minutes. The mixture was then added to the polymerization system and stirred for 5.0 hours. Finally, 50g of butanol was added. The product was discharged, condensed, washed, and dried to obtain a brominated hyperbranched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0097] Comparative Example 1

[0098] (1) Preparation of quaternary three-arm brominated grafting agent: Other conditions were the same as those in Example 1, except that p-bromomethylstyrene was not added during the preparation of the quaternary three-arm brominated grafting agent. That is, first, argon was introduced into a 15L stainless steel reactor A with a jacket, and 3000g of hexane, 600g of isoprene, and 1g of THF were added to the reactor in sequence. The temperature was raised to 40°C, and 30.2mmol of n-butyllithium was added to start the reaction for 50min to form -IR- segments. Then, 400g of 1,3-butadiene and 0.5g of THF were added to the reactor A in sequence, and the temperature was raised to 60°C and the reaction was carried out for 40min to form -IR-BR- segments. Then, 300g of styrene and 500g of 1,3-butadiene, 2.0g of THF, heated to 70 ° C, reacted for 60 minutes to form -IR-BR--SBR- segments, and then 10.5 mmol n-butyl lithium was added to reactor A and reacted for 80 minutes until no free monomers were present; finally, reactor A was heated to 80 ° C, 90.5 mmol tert-butyltrichlorosilane was added for coupling reaction, and after reacting for 90 minutes, the coupled reaction mixture was treated with water, and the glue was wet coagulated and dried to obtain a quaternary three-arm brominated grafting agent-1 (Mn is 42000, Mw / Mn is 7.65).

[0099] (2) Preparation of brominated hyperbranched butyl rubber: Other conditions were the same as those in Example 1, except that: in the preparation of brominated hyperbranched butyl rubber, instead of adding a quaternary three-arm brominated grafting agent, a quaternary three-arm brominated grafting agent-1 was added in an amount of 35.0 g. That is, first, in a 4 L stainless steel reactor with a jacket, nitrogen was passed through and replaced three times, 150 g of dichloromethane, 350 g of hexane, and 35.0 g of the quaternary three-arm brominated grafting agent-1 were added to the reactor, and the mixture was stirred and dissolved for 80 min until it was completely dissolved. The mixture was then cooled to -80°C, followed by the addition of 500g of dichloromethane, 450g of isobutylene, and 15.0g of isoprene. The mixture was stirred until the polymerization temperature dropped to -90°C. Then, 100g of dichloromethane, 1.65g of sesquiethylaluminum chloride, and 0.031g of HCl were mixed and aged at -85°C for 30 minutes before being added to the polymerization system and stirred for 3.0 hours. Finally, 25g of butanol was added, the product was discharged, coagulated, washed, and dried to obtain a brominated highly branched butyl rubber product. Sampling and Analysis: Standard specimens were prepared. The test properties are shown in Table 1.

[0100] Comparative Example 2

[0101] (1) Preparation of quaternary three-arm brominated grafting agent: other conditions are the same as those in Example 2, except that: in the preparation process of quaternary three-arm brominated grafting agent, instead of adding p-bromomethylstyrene, allyl bromide is added in an amount of 1000 g, that is: first, in a 15 L stainless steel reactor A with a jacket, argon is replaced twice, 3100 g hexane, 630 g isoprene, and 1.5 g THF are added to the reactor in sequence, the temperature is raised to 42° C., 35.5 mmol n-butyl lithium is added to start the reaction for 53 min to form -IR- segment; then 420 g 1,3-butadiene and 0.8 g THF are added to the reactor A in sequence, the temperature is raised to 62° C., and the reaction is carried out for 43 min to form -IR-BR- segment; then 320 g styrene and 510 g 1,3-butadiene, 2.5 g THF, heated to 71°C, reacted for 63 minutes to form -IR-BR--SBR- segments, and then added 1000g allyl bromide and 11.5mmol n-butyl lithium to reactor A, and reacted for 82 minutes until no free monomers existed; finally, reactor A was heated to 81°C, and 100.2mmol tert-butyltrichlorosilane was added for coupling reaction. After reacting for 95 minutes, the coupled reaction mixture was treated with water, and the glue was wet coagulated and dried to obtain quaternary three-arm brominated grafting agent-2 (Mn is 46000, Mw / Mn is 8.12).

[0102] (2) Preparation of brominated hyperbranched butyl rubber: Other conditions were the same as those in Example 2, except that: in the preparation of brominated hyperbranched butyl rubber, instead of adding a quaternary three-arm brominated grafting agent, a quaternary three-arm brominated grafting agent-2 was added in an amount of 40.0 g. That is, first, in a 4L stainless steel reactor with a jacket, nitrogen was passed through and replaced three times, 200 g of dichloromethane, 300 g of hexane, and 40.0 g of the quaternary three-arm brominated grafting agent-2 were added to the reactor, and the mixture was stirred and dissolved for 84 min until it was completely dissolved. The mixture was then cooled to -82°C, followed by the addition of 600g of dichloromethane, 440g of isobutylene, and 20.0g of isoprene. The mixture was stirred until the polymerization temperature dropped to -92°C. Then, 110g of dichloromethane, 1.86g of sesquiethylaluminum chloride, and 0.045g of HCl were mixed and aged at -87°C for 33 minutes before being added to the polymerization system. The mixture was stirred and reacted for 3.4 hours. Finally, 30g of butanol was added. The product was discharged, coagulated, washed, and dried to obtain a brominated highly branched butyl rubber product. Sampling and Analysis: Standard specimens were prepared. The test properties are shown in Table 1.

[0103] Comparative Example 3

[0104] (1) Preparation of quaternary three-arm brominated grafting agent: Other conditions were the same as those in Example 3, except that: in the preparation process of the quaternary three-arm brominated grafting agent, 300 g of bromomethylstyrene was added, namely: first, in a 15 L stainless steel reactor A with a jacket, argon was replaced three times, 3300 g of hexane, 660 g of isoprene, and 2.0 g of THF were added to the reactor in sequence, the temperature was raised to 44° C., 39.5 mmol of n-butyl lithium was added to start the reaction for 57 min to form -IR- segment; then 480 g of 1,3-butadiene and 1.0 g of THF were added to the reactor A in sequence, the temperature was raised to 64° C., and the reaction was carried out for 48 min to form -IR-BR- segment; then 350 g of styrene and 530 g of 1,3-butadiene, 3.0 g of THF, heated to 73°C, reacted for 66 minutes to form -IR-BR--SBR- segments, and then added 300g of p-bromomethylstyrene and 12.5mmol of n-butyllithium to reactor A, and reacted for 84 minutes until no free monomers were present; finally, the reactor A was heated to 83°C, and 120.2mmol of tert-butyltrichlorosilane was added for coupling reaction. After reacting for 100 minutes, the coupled reaction mixture was treated with water, and the glue was wet-coagulated and dried to obtain a quaternary three-arm brominated grafting agent-3 (Mn is 72000, Mw / Mn is 8.56).

[0105] (2) Preparation of brominated hyperbranched butyl rubber: Other conditions were the same as those in Example 3, except that: in the preparation of brominated hyperbranched butyl rubber, instead of adding a quaternary three-arm brominated grafting agent, a quaternary three-arm brominated grafting agent-3 was added in an amount of 45.0 g. That is, first, in a 4L stainless steel reactor with a jacket, nitrogen was passed through and replaced 4 times, 350 g of dichloromethane, 150 g of hexane, and 45.0 g of the quaternary three-arm brominated grafting agent-3 were added to the reactor, and the mixture was stirred and dissolved for 88 min until it was completely dissolved. The mixture was then cooled to -84°C, followed by the addition of 700g of dichloromethane, 430g of isobutylene, and 25.0g of isoprene. The mixture was stirred until the polymerization temperature dropped to -94°C. Then, 120g of dichloromethane, 2.06g of sesquiethylaluminum chloride, and 0.058g of HCl were mixed and aged at -89°C for 38 minutes before being added to the polymerization system and stirred for 3.7 hours. Finally, 34g of butanol was added, the product was discharged, coagulated, washed, and dried to obtain a brominated highly branched butyl rubber product. Sampling and Analysis: Standard specimens were prepared. The test properties are shown in Table 1.

[0106] Comparative Example 4

[0107] Preparation of brominated hyperbranched butyl rubber: Other conditions are the same as those in Example 4, except that: during the preparation of brominated hyperbranched butyl rubber, no quaternary three-arm brominated grafting agent is added, but p-bromomethylstyrene is directly added in an amount of 50.0 g. That is: first, in a 4L stainless steel reactor with a jacket, nitrogen is replaced 4 times, 560 g of dichloromethane, 240 g of hexane, and 50.0 g of p-bromomethylstyrene are added to the reactor, and stirred and dissolved for 90 minutes until completely dissolved. Then, when the temperature is cooled to -85°C, 800 g of dichloromethane, 420 g of isobutylene, and 30.0 g of isoprene are added in sequence, and stirred and mixed until the polymerization system temperature drops to -95°C. Then, 130 g of dichloromethane, 2.46 g of sesquiethylaluminum chloride and HCl are added. After mixing and aging 0.062g of the butyl rubber at -90°C for 41 minutes, the mixture was added to the polymerization system and stirred for 4.0 hours. Finally, 40g of butanol was added. The product was then coagulated, washed, and dried to obtain brominated highly branched butyl rubber. Sampling and Analysis: Standard specimens were prepared. The test properties are shown in Table 1.

[0108] Comparative Example 5

[0109] (1) Preparation of a quaternary three-arm brominated grafting agent: same as in Example 5.

[0110] (2) Preparation of brominated hyperbranched butyl rubber: Other conditions were the same as those in Example 5, except that 15.0 g of the quaternary three-arm brominated grafting agent was added during the preparation of the brominated hyperbranched butyl rubber. Specifically, 500 g of dichloromethane, 300 g of hexane, and 15.0 g of the quaternary three-arm brominated grafting agent were added to a 4 L stainless steel reactor with a jacket, and the mixture was replaced with nitrogen 4 times. The mixture was stirred and dissolved for 93 minutes until the mixture was completely dissolved. The mixture was then cooled to -87°C, and 900 g of dichloromethane, 410 g of isobutylene, and 35.0 g of isoprene were added in sequence. The mixture was stirred and mixed until the polymerization temperature dropped to -97°C. Then, 140 g of dichloromethane, 2.83 g of sesquiethylaluminum chloride, and HCl were added. After mixing and aging 0.071 g of the butyl rubber at -92°C for 45 minutes, the mixture was added to the polymerization system and stirred for 4.3 hours. Finally, 43 g of butanol was added. The product was then coagulated, washed, and dried to obtain brominated highly branched butyl rubber. Sampling and Analysis: Standard samples were prepared, and the test properties are shown in Table 1.

[0111] Comparative Example 6

[0112] (1) Preparation of quaternary three-arm brominated grafting agent: Other conditions were the same as those in Example 6, except that tert-butyltrichlorosilane was not added for coupling during the preparation of the quaternary three-arm brominated grafting agent. That is, first, argon was introduced into a 15L stainless steel reactor A with a jacket, and 3800g of hexane, 780g of isoprene, and 3.5g of THF were added to the reactor in sequence. The temperature was raised to 48°C, and 47.5mmol of n-butyl lithium was added to start the reaction for 67min to form -IR- segments. Then, 560g of 1,3-butadiene and 1.8g of THF were added to the reactor A in sequence. The temperature was raised to 68°C and the reaction was carried out for 58min to form -IR-BR- segments. Then, 460g of styrene and 580g of 1,3-butadiene, 4.5g of THF, heated to 77 ° C, reacted for 75 minutes to form -IR-BR--SBR- segment, and then added 1000g of p-bromomethylstyrene and 13.5mmol of n-butyl lithium to reactor A and reacted for 88 minutes until no free monomers were present; the glue was wet coagulated and dried to obtain a quaternary three-arm brominated grafting agent-4 (Mn is 93000, Mw / Mn is 3.56).

[0113] (2) Preparation of brominated hyperbranched butyl rubber: Other conditions were the same as those in Example 6, except that: in the preparation of brominated hyperbranched butyl rubber, instead of adding a quaternary three-arm brominated grafting agent, a quaternary three-arm brominated grafting agent-4 was added in an amount of 57.0 g. That is, first, in a 4 L stainless steel reactor with a jacket, nitrogen was replaced 4 times, 400 g of dichloromethane, 400 g of hexane, and 57.0 g of the quaternary three-arm brominated grafting agent-4 were added to the reactor, and the mixture was stirred and dissolved for 95 min until it was completely dissolved. The mixture was then cooled to -88°C, followed by the addition of 950g of dichloromethane, 405g of isobutylene, and 38.0g of isoprene. The mixture was stirred and mixed until the polymerization temperature dropped to -98°C. Then, 145g of dichloromethane, 3.13g of sesquiethylaluminum chloride, and 0.085g of HCl were mixed and aged at -94°C for 48 minutes before being added to the polymerization system and stirred for 4.6 hours. Finally, 45g of butanol was added, the product was discharged, coagulated, washed, and dried to obtain a brominated highly branched butyl rubber product. Sampling and Analysis: Standard specimens were prepared. The test properties are shown in Table 1.

[0114] Comparative Example 7

[0115] (1) Preparation of quaternary three-arm brominated grafting agent: Other conditions were the same as those in Example 7, except that: no isoprene monomer was added during the preparation of the quaternary three-arm brominated grafting agent, and no IR segment was formed. That is: first, argon was replaced four times in a 15L stainless steel reactor A with a jacket, 4000g of hexane, 600g of 1,3-butadiene, and 2.0g of THF were added to the reactor in sequence, the temperature was raised to 70°C, 50.5mmol of n-butyllithium was added, and the reaction was started for 60min to form -BR- segments; then 500g of styrene and 600g of 1,3-butadiene, 5.0g of THF, heated to 80°C, reacted for 80 minutes to form -BR--SBR- segments, and then added 1000g of p-bromomethylstyrene and 14.1mmol of n-butyllithium to reactor A and reacted for 90 minutes until no free monomers were present; finally, reactor A was heated to 90°C, 260.5mmol of tert-butyltrichlorosilane was added for coupling reaction, and after reacting for 120 minutes, the coupled reaction mixture was treated with water, and the glue was wet-coagulated and dried to obtain a quaternary three-arm brominated grafting agent-5 (Mn is 71000, Mw / Mn is 8.58).

[0116] (2) Preparation of brominated hyperbranched butyl rubber: Other conditions were the same as those in Example 7, except that: in the preparation of brominated hyperbranched butyl rubber, instead of adding a quaternary three-arm brominated grafting agent, a quaternary three-arm brominated grafting agent-5 was added in an amount of 60.0 g. That is, first, in a 4 L stainless steel reactor with a jacket, nitrogen was passed through and replaced 5 times, 700 g of dichloromethane, 300 g of hexane, and 60.0 g of the quaternary three-arm brominated grafting agent-5 were added to the reactor, and the mixture was stirred and dissolved for 100 min until it was completely dissolved. The mixture was then cooled to -90°C, followed by the addition of 1000g of dichloromethane, 400g of isobutylene, and 40.0g of isoprene. The mixture was stirred and mixed until the polymerization temperature dropped to -98°C. Then, 150g of dichloromethane, 3.35g of sesquiethylaluminum chloride, and 0.096g of HCl were mixed and aged at -95°C for 50 minutes before being added to the polymerization system and stirred for 5.0 hours. Finally, 50g of butanol was added, the product was discharged, coagulated, washed, and dried to obtain a brominated highly branched butyl rubber product. Sampling and Analysis: Standard specimens were prepared. The test properties are shown in Table 1.

[0117] Table 1 Properties of brominated highly branched butyl rubber

[0118]

[0119]

[0120] Note: 10 The scorch time reflects the size of the scorch safety window; t 90The positive vulcanization time reflects the speed of vulcanization.

[0121] As shown in Table 1, the brominated branched butyl rubber of the present invention has a high degree of branching, a high vulcanization rate and a short Mooney stress relaxation time, showing good processing and vulcanization characteristics, while maintaining a high tensile strength and good air tightness.

[0122] The above embodiments are typical examples listed to illustrate the technical solutions of the present invention in detail. The present invention is subject to the scope of protection of the claims and the content of the invention and is not limited to the implementation scheme. Simple replacement or modification of the present invention is still within the scope of protection of the invention.

Claims

1. A method for preparing brominated highly branched butyl rubber, comprising the following steps: S1: adding a quaternary three-arm brominated grafting agent to a mixed solvent and stirring thoroughly until the quaternary three-arm brominated grafting agent is completely dissolved to obtain a mixed solution; S2: Cooling the mixture, sequentially adding a diluent, isobutylene, and isoprene to the mixed solution of step S1, stirring and mixing the mixture to obtain a polymerization reaction system, and cooling the mixture again; S3: mixing the diluent and the co-initiator and aging them, then adding them to the polymerization reaction system of step S2, stirring them thoroughly for reaction, adding a terminator, coagulating the discharged material, washing, and drying it to obtain brominated highly branched butyl rubber; It is characterized in that the quaternary three-arm brominated grafting agent is a quaternary three-arm all-primary brominated star block copolymer composed of isoprene, 1,3-butadiene, styrene and a reactive brominating agent, and its general structural formula is shown in Formula I: Among them, Bu is tert-butyl; IR is an isoprene homopolymer block; BR is a 1,3-butadiene homopolymer segment; SBR is a styrene-butadiene random block copolymer; m is the number of repeating units, and m is an integer ≥1; the number average molecular weight (Mn) of the quaternary three-arm brominated grafting agent is 80,000 to 100,000, and the molecular weight distribution (Mw / Mn) is 9.13 to 11.

05.

2. The method for preparing brominated highly branched butyl rubber according to claim 1, wherein In step S1, the mass ratio of the mixed solvent to the quaternary three-arm brominated grafting agent is 100-200:7-12; the mixed solvent includes a diluent and a solvent, and the volume ratio of the diluent to the solvent is 70-30 / 30-70.

3. The method for preparing brominated highly branched butyl rubber according to claim 2, wherein: The solvent is selected from at least one of pentane, hexane, octane, heptane, cyclohexane, benzene, toluene, xylene and ethylbenzene.

4. The method for preparing brominated highly branched butyl rubber according to claim 2, wherein: The solvent is hexane.

5. The method for preparing brominated highly branched butyl rubber according to claim 1, wherein In step S2, the temperature is lowered to -80 to -90°C, and the temperature is lowered again to -100 to -90°C.

6. The method for preparing brominated highly branched butyl rubber according to claim 1, wherein: In step S2, the mass ratio of the diluent, isobutylene and isoprene is 100-200:80-90:3-8.

7. The method for preparing brominated highly branched butyl rubber according to claim 1, wherein: In step S3, the mass ratio of the diluent, the co-initiator and the terminator is 20-30:0.3-0.7:5-10.

8. The method for preparing brominated highly branched butyl rubber according to claim 1, wherein: The preparation method of the quaternary three-arm brominated grafting agent specifically comprises the following steps: Based on 100 parts by weight of the reactive brominating agent, 300 wt% to 400 wt% of solvent, 60 wt% to 80 wt% of isoprene, and 0.1 wt% to 0.4 wt% of a structure regulator are first added sequentially to a reactor after inert gas replacement, the temperature is raised to 40 to 50° C., an initiator is added, and the reaction is carried out for 50 to 70 minutes to form an -IR- segment; then 40 wt% to 60 wt% of 1,3-butadiene and 0.05 wt% to 0.2 wt% of a structure regulator are added sequentially to reactor A, the temperature is raised to 60 to 70° C., and the reaction is carried out for 40 to 60 minutes to form an -IR-BR- segment; then, 2, 3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 42, 39, 43, 30, 31, 32, 34, 35, 37, 38, 39, 40, 42, 31, 32, 33, 34, 35, 36 ... 30 wt% to 50 wt% of styrene, 50 wt% to 60 wt% of 1,3-butadiene, and 0.2 to 0.5 wt% of a structure regulator are added, the temperature is raised to 70 to 80° C., and the reaction is carried out for 60 to 80 minutes to form -IR-BR--SBR- segments. Then, 100 wt% of a reactive brominating agent and an initiator are added to the reactor A, and the reaction is carried out for 80 to 90 minutes until no free monomers are present. Finally, the reactor A is heated to 80 to 90° C., a coupling agent is added to carry out a coupling reaction, and the reaction mixture after the reaction is treated with water after 90 to 120 minutes. The reaction mixture is subjected to wet coagulation and drying to obtain a quaternary three-arm brominated grafting agent.

9. The method for preparing brominated highly branched butyl rubber according to claim 8, wherein: The initiator is a hydrocarbon monolithium compound RLi, selected from at least one of n-butyllithium, sec-butyllithium, methylbutyllithium, phenylbutyllithium, naphthalenelithium, cyclohexyllithium, and dodecyllithium; The structure regulator is a polar organic compound selected from at least one of diethylene glycol dimethyl ether (2G), tetrahydrofuran (THF), ethyl ether, ethyl methyl ether, anisole, diphenyl ether, ethylene glycol dimethyl ether (DME), and triethylamine; The reactive brominating agent is p-bromomethylstyrene.

10. The method for preparing brominated highly branched butyl rubber according to claim 8, characterized in that: The initiator is n-butyl lithium.

11. The method for preparing brominated highly branched butyl rubber according to claim 8, wherein: The structure regulator is tetrahydrofuran (THF).

12. The method for preparing brominated highly branched butyl rubber according to claim 8, wherein: The coupling agent is a halogen silane coupling agent, selected from one of tert-butyltrichlorosilane and tert-butyltribromosilane; the molar ratio of the coupling agent to the initiator is 2:1 to 6:

1.

13. The method for preparing brominated highly branched butyl rubber according to claim 8, wherein: The coupling agent is tert-butyltrichlorosilane.

14. The method for preparing brominated highly branched butyl rubber according to claim 8, wherein: The solvent is selected from at least one of pentane, hexane, octane, heptane, cyclohexane, benzene, toluene, xylene and ethylbenzene.

15. The method for preparing brominated highly branched butyl rubber according to claim 8, wherein: The solvent is hexane.

16. The method for preparing brominated highly branched butyl rubber according to claim 1, wherein: The diluent is a halogenated alkane, selected from at least one of monochloromethane, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloropropane, heptachloropropane, monofluoromethane, difluoromethane, tetrafluoroethane, carbon hexafluoride, and fluorobutane.

17. The method for preparing brominated highly branched butyl rubber according to claim 1, wherein: The diluent is methyl chloride.

18. The method for preparing brominated highly branched butyl rubber according to claim 1, wherein: The co-initiator is composed of an alkyl aluminum halide and a protonic acid mixed in proportion; the alkyl aluminum halide is selected from at least one of diethylaluminum monochloride, diisobutylaluminum monochloride, methylaluminum dichloride, sesquiethylaluminum chloride, sesquiisobutylaluminum chloride, n-propylaluminum dichloride, isopropylaluminum dichloride, dimethylaluminum chloride and ethylaluminum chloride; the protonic acid is selected from at least one of HCl, HF, HBr, H2SO4, H2CO3, H3PO4 and HNO3; and the molar ratio of the protonic acid to the alkyl aluminum halide is 0.07:1 to 0.6:

1.

19. The method for preparing brominated highly branched butyl rubber according to claim 18, characterized in that: The alkylaluminum halide is ethylaluminum sesquichloride.

20. The method for preparing brominated highly branched butyl rubber according to claim 18, wherein: The protonic acid is HCl.

21. The method for preparing brominated highly branched butyl rubber according to claim 1, wherein: The terminator is at least one of methanol, ethanol and butanol.

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