A preparation method of secondary brominated branched butyl rubber

Abstract

The invention discloses a method for preparing a secondary brominated branched butyl rubber. The method comprises adding a high molecular weight brominated grafting agent to a mixed solvent, stirring the mixture until the high molecular weight brominated grafting agent is completely dissolved, and obtaining a mixed solution; cooling the mixture, sequentially adding a diluent, isobutylene, and isoprene to the mixed solution, stirring and mixing the mixture, and obtaining a polymerization reaction system; and cooling the mixture again; mixing the diluent and a co-initiator, aging the mixture, and then adding the mixture to the polymerization reaction system, stirring and reacting the mixture, adding a terminator, and coagulating the material, washing, and drying the material to obtain a secondary brominated branched butyl rubber; the high molecular weight brominated grafting agent is a linear block copolymer composed of isoprene, styrene, and vinyl bromide. The preparation method of the invention not only solves the problem of slow stress relaxation rate of butyl rubber during processing, but also maintains sufficient green rubber strength and good air tightness, and provides a balance between physical and mechanical properties and vulcanization processing performance.

Description

Technical Field

[0001] The present invention relates to a method for preparing secondary brominated branched butyl rubber, in particular to a method for grafting butyl rubber onto a secondary brominated isoprene / styrene block copolymer. 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] 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, neutralization, and product recovery are performed to obtain brominated star-branched butyl rubber. This process dissolves residual branching agent in the star-branched butyl rubber before bromination, preventing it from combining with the HBr byproduct produced during the bromination process. This improves neutralization efficiency and inhibits the isomerization of Type II secondary structures to Type III primary structures.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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

[0011] The present invention aims to provide a method for preparing secondary brominated branched butyl rubber. This method uses a macromolecular brominating agent as a raw material, and the macromolecular brominating agent has anionic reactivity. Subsequently, an alkyl lithium is used as an initiator to synthesize a high-molecular brominated grafting agent from isoprene, styrene, and the macromolecular brominating agent. Finally, the high-molecular brominated grafting agent, isobutylene, and isoprene are subjected to cationic polymerization in the presence of a catalytic system comprising an alkyl aluminum halide and a protonic acid to prepare the brominated branched butyl rubber. The present invention utilizes a brominating agent containing an unsaturated double bond to prepare the brominated branched butyl rubber through an addition polymerization reaction, rather than the ionic substitution reaction used in the prior art. This method avoids the molecular rearrangement of the secondary bromine in the brominated branched butyl rubber to form primary bromine due to the production of hydrogen bromide as a byproduct, thereby resolving the structural stability issue of the secondary bromine in the brominated branched butyl rubber and improving the vulcanization rate of the butyl rubber. At the same time, by branching butyl rubber, not only the problem of slow stress relaxation rate of butyl rubber during processing is solved, but also the butyl rubber is kept with sufficient raw rubber strength and good air tightness, giving butyl rubber a balance between physical and mechanical properties and vulcanization processing performance.

[0012] Unless otherwise specified, the "%" mentioned in the present invention refers to mass percentage.

[0013] To achieve the above object, the present invention provides a method for preparing a secondary brominated branched butyl rubber, the preparation method comprising the following steps:

[0014] S1: adding a high molecular weight brominated grafting agent to a mixed solvent and stirring thoroughly until the high molecular weight brominated grafting agent is completely dissolved to obtain a mixed solution;

[0015] 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;

[0016] 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 a secondary brominated branched butyl rubber;

[0017] It is characterized in that the polymer brominated grafting agent is a linear block copolymer composed of isoprene, styrene and vinyl bromide, and its general structural formula is shown in Formula I:

[0018]

[0019] Wherein, IR is an isoprene homopolymer block; PS is a styrene homopolymer block; m and n are the number of repeating units, m is an integer ≥1, and n is an integer ≥1; the number average molecular weight (Mn) of the polymer brominated grafting agent is 27,000 to 45,000, and the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) is 1.57 to 2.64.

[0020] In the method for preparing secondary brominated branched butyl rubber of the present invention, in step S1, the mass ratio of the mixed solvent to the high molecular weight brominated grafting agent is 100-200:3-6.

[0021] In the method for preparing secondary brominated branched butyl rubber of the present invention, in step S1, the mixed solvent includes a diluent and a solvent, and the volume ratio of the diluent to the solvent is 70-30 / 30-70.

[0022] In the method for preparing secondary brominated branched butyl rubber of the present invention, in step S2, the temperature is lowered to -60°C to -80°C.

[0023] In the method for preparing secondary brominated branched butyl rubber of the present invention, in step S2, the mass ratio of the diluent, isobutylene and isoprene is 100-200:90-95:2-4.

[0024] In the method for preparing secondary brominated branched butyl rubber of the present invention, in step S2, the temperature is lowered again to a temperature of -100 to -90°C.

[0025] In the method for preparing secondary brominated branched butyl rubber of the present invention, in step S3, the mass ratio of the diluent, the co-initiator and the terminator is 20-30:0.01-1.0:5-10.

[0026] In the preparation method of the secondary brominated branched butyl rubber of the present invention, in step S3, the aging temperature is -95°C to -85°C, and the aging time is 20 to 30 minutes.

[0027] In the method for preparing secondary brominated branched butyl rubber of the present invention, in step S3, the drying temperature is 60-70° C. and the drying time is 25-35 hr.

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

[0029] a. Preparation of a macromolecular brominating agent: First, based on 100 parts of vinyl bromide by mass, 100-200 parts of solvent, 100 parts of vinyl bromide, and 0.1-0.3 parts of a molecular weight regulator are added sequentially to a reactor after inert gas replacement, stirred and mixed, and heated. When the temperature of the reactor reaches 40-60°C, 0.05-0.2 parts of a first initiator are added and reacted for 2.0-4.0 hours until the vinyl bromide monomer conversion reaches 100%. Then, 5-10 parts of isoprene are added to the reactor for end-capping, and the reaction is carried out for 30-50 minutes until no free monomer is present. After the reaction is completed, the mixture is washed and dried to obtain a macromolecular brominating agent.

[0030] b. Preparation of a high molecular weight brominated grafting agent: Based on 100% by weight of the reaction monomer isoprene, 300 wt% to 400 wt% of a solvent, 100 wt% of isoprene, and 0.1 wt% to 0.3 wt% of a structure regulator are first added sequentially to a reactor replaced with inert gas. After the temperature is raised to 40-50° C., a second initiator is added and the reaction is carried out for 50-70 minutes. Then, 20 wt% to 30 wt% of styrene is added to the reactor, the temperature is raised to 60-70° C., and the reaction is carried out for 40-60 minutes to form -IR-PS- segments. Finally, 40 wt% to 60 wt% of a high molecular weight brominating agent is added to the reactor, the temperature is raised to 80-85° C., and the reaction is carried out for 50-80 minutes until no free monomer is present. After the reaction is completed, the reactor is subjected to wet coagulation and drying to obtain a high molecular weight brominated grafting agent.

[0031] In the preparation method of the secondary brominated branched butyl rubber of the present invention, the molecular weight regulator can be selected from at least one of tert-decyl mercaptan, tert-dodecyl mercaptan, tert-tetradecyl mercaptan and tert-hexadecanethiol, preferably tert-dodecyl mercaptan.

[0032] In the preparation method of the secondary brominated branched butyl rubber of the present invention, the first initiator is an organic peroxide, selected from at least one of di-tert-butyl hydroperoxide (TBHP), 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane (BPDH), di-tert-butyl peroxide (DTBP), and dicumyl peroxide (DCP), preferably DCP.

[0033] The method for preparing secondary brominated 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 regulate 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), ether, ethyl methyl ether, anisole, diphenyl ether, ethylene glycol dimethyl ether (DME), and triethylamine, preferably tetrahydrofuran (THF).

[0034] In the method for preparing secondary brominated branched butyl rubber of the present invention, the second initiator 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 n-butyllithium, sec-butyllithium, methylbutyllithium, phenylbutyllithium, naphthalenelithium, cyclohexyllithium, and dodecyllithium, with n-butyllithium being preferred. The amount of the second initiator added is determined by the molecular weight of the designed polymer.

[0035] The polymerization reaction in the method for preparing the secondary brominated branched butyl rubber of the present invention is carried out in an oxygen-free, 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 cyclohexane being preferred.

[0036] In the method for preparing secondary brominated branched butyl rubber of the present invention, the diluent is a halogenated alkane; 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, preferably monochloromethane.

[0037] The present invention provides a method for preparing secondary brominated branched butyl rubber. The co-initiator comprises an alkyl aluminum halide and a protonic acid mixed 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 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 0.01:1 to 0.1:1.

[0038] In the method for preparing secondary brominated branched butyl rubber of the present invention, the terminator may be, for example but not limited to, at least one of methanol, ethanol, and butanol.

[0039] The present invention can also be described in detail as follows:

[0040] In detail, the specific process of the preparation method of the secondary brominated branched butyl rubber of the present invention comprises the following steps:

[0041] (1) Preparation of high molecular weight brominated grafting agent:

[0042] a. Preparation of a macromolecular brominating agent: Based on 100 parts of vinyl bromide, first, in a 15L jacketed stainless steel reactor, replace the atmosphere with inert gas 2-4 times, then sequentially add 100-200 parts of solvent, 100 parts of vinyl bromide, and 0.1-0.3 parts of a molecular weight regulator to the reactor, stir and mix, and heat. When the reactor temperature reaches 40-60°C, add 0.05-0.2 parts of a first initiator and react for 2.0-4.0 hours, at which point the vinyl bromide monomer conversion reaches 100%. Then, add 5-10 parts of isoprene to the reactor for end-capping, and react for 30-50 minutes until no free monomer is present. After completion of the reaction, wash and dry the mixture to obtain a macromolecular brominating agent.

[0043] b. Preparation of a high molecular weight brominated grafting agent: First, in a 15 L stainless steel reactor with a jacket, argon gas is replaced 2 to 4 times, and 300 wt% to 400 wt% of solvent, 100 wt% of isoprene, and 0.1 wt% to 0.3 wt% of a structure regulator are added to the reactor in sequence. The temperature is raised to 40 to 50° C., and a second initiator is added and reacted for 50 to 70 minutes. Then, 20 wt% to 30 wt% of styrene is added to the reactor, and the temperature is raised to 60 to 70° C. and reacted for 40 to 60 minutes to form -IR-PS- segments. Finally, 40 wt% to 60 wt% of a high molecular weight brominating agent is added to the reactor, and the temperature is raised to 80 to 85° C. and reacted for 50 to 80 minutes until no free monomer is present. After completion of the reaction, the reactor is subjected to wet coagulation and drying to obtain a high molecular weight brominated grafting agent.

[0044] (2) Preparation of secondary brominated 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 3wt% to 6wt% of a high molecular weight brominated grafting agent are added to the reactor, and stirred and dissolved for 30 to 50 minutes until the grafting agent is completely dissolved; then, when the temperature is lowered to -60°C to -80°C, 100wt% to 200wt% of a diluent and 100wt% of a grafting agent are added in sequence. The invention discloses a method for preparing a brominated branched butyl rubber product comprising the steps of: preparing a first polymerization product comprising ...

[0045] The high molecular weight brominated grafting agent of the present invention is a linear block copolymer composed of isoprene, styrene and vinyl bromide, and its general structural formula is shown in Formula I:

[0046]

[0047] wherein IR is an isoprene homopolymer block; PS is a styrene homopolymer block; m and n are the number of repeating units; and the number average molecular weight (Mn) of the high molecular weight brominated grafting agent is 27,000 to 45,000, and the molecular weight distribution (Mw / Mn) is 1.57 to 2.64.

[0048] The preparation process of the high molecular weight brominated grafting agent of the present invention firstly involves free radical polymerization of vinyl bromide to generate a high molecular weight brominated agent, and then using isoprene to perform end-capping and activation treatment on the high molecular weight brominated agent to make it have anionic reaction activity and be able to undergo anionic polymerization with the high polymer [-PS-IR-]m to generate the high molecular weight brominated grafting agent.

[0049] The high molecular weight brominated grafting agent of the present invention mainly plays three roles:

[0050] On the one hand, the invention plays a role in preventing the rearrangement of the bromine structure in the brominated branched butyl rubber. This is mainly because the secondary bromine structure in the high molecular weight brominated grafting agent is generated through addition polymerization rather than ion substitution in the prior art, thereby avoiding the generation of by-product hydrogen bromide (HBr) and blocking the conditions for the isomerization of the secondary bromine structure to the primary structure, thereby greatly inhibiting the molecular rearrangement of the secondary bromine in the brominated branched butyl rubber to form primary bromine, improving the stability of the secondary bromine structure in the brominated branched butyl rubber, increasing the vulcanization speed, and solving the problem of slow vulcanization speed of butyl rubber during processing.

[0051] Secondly, it plays a role in improving the utilization rate of bromine elements. The high-molecular-weight brominated grafting agent uses an organic brominating agent containing an unsaturated double bond to first undergo free radical polymerization to generate a macromolecular brominating agent, which then participates in an anion reaction. No HBr is generated during the entire reaction process, avoiding the loss of remaining bromine, increasing the reaction degree of the organic brominating agent, and improving the utilization rate of bromine elements in brominated branched butyl rubber. At the same time, the alkali washing and recovery process of the by-product HBr is omitted, thereby shortening the process flow and reducing production costs.

[0052] The third aspect is to prevent the strength and air tightness of brominated branched butyl rubber from decreasing. The -PS- polymer chain segment in the high molecular weight brominated grafting agent contains a large number of benzene rings. The benzene rings have the characteristics of high rigidity and large steric hindrance, which can avoid the molecular weight distribution of butyl rubber from becoming wider due to branching, thereby causing the strength and air tightness of butyl rubber to decrease.

[0053] Therefore, the polymer brominated grafting agent designed in the present invention organically combines the properties of the brominating agent and the two polymer chain segments -IR- and -PS-, and synergistically exerts them, thereby achieving the stability of the secondary bromine structure in the brominated branched butyl rubber. This not only effectively solves the problems of slow stress relaxation rate and slow vulcanization rate of butyl rubber during processing, but also maintains sufficient green rubber strength and good air tightness of butyl rubber, thus giving butyl rubber a balance between physical and mechanical properties and processing performance.

[0054] In summary, the present invention has the following beneficial effects:

[0055] 1. The secondary bromine structure contained in the high molecular weight brominated grafting agent of the present invention is generated by addition polymerization rather than ion substitution as in the prior art, thereby avoiding the generation of hydrogen bromide (HBr) as a by-product and blocking the conditions for isomerization of the secondary bromine structure to the primary structure, thereby greatly inhibiting the molecular rearrangement of the secondary bromine in the brominated branched butyl rubber to form primary bromine, improving the stability of the secondary bromine structure in the brominated branched butyl rubber, increasing the vulcanization rate, and solving the problem of slow vulcanization rate of butyl rubber during processing.

[0056] 2. The high molecular weight brominated grafting agent of the present invention first undergoes free radical polymerization with an organic brominating agent containing an unsaturated double bond to generate a macromolecular brominating agent, which then participates in an anion reaction. No HBr is generated during the entire reaction process, thereby avoiding the loss of remaining bromine, increasing the reaction degree of the organic brominating agent, and improving the utilization rate of the bromine element in the brominated branched butyl rubber.

[0057] 3. The high molecular weight brominated grafting agent of the present invention does not generate a by-product HBr during the entire reaction process, thereby reducing the harm to humans and the environment and eliminating the alkali washing and recovery process of the by-product HBr, thereby shortening the process and reducing production costs.

[0058] 4. The high molecular weight brominated grafting agent of the present invention contains a [-PS-IR-]m chain segment. The molecular chain structure is non-polar and contains a benzene ring structure. The benzene ring has the characteristics of high rigidity and large steric hindrance. It can avoid the problem of butyl rubber having a widened molecular weight distribution due to branching, thereby reducing the strength and air tightness of butyl rubber.

[0059] 5. The polymer brominated grafting agent of the present invention is a new type of safe and environmentally friendly compound that does not emit atmospheric pollutants (VOCs) and by-product HBr. Its preparation method is green and environmentally friendly, the process flow is short, the bromine structure is controllable, and it exhibits good processability and is suitable for industrial production. DETAILED DESCRIPTION

[0060] 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.

[0061] (1) Source of raw materials:

[0062] Styrene, polymer grade, PetroChina Lanzhou Petrochemical Company;

[0063] Isobutylene, isoprene, polymer grade Zhejiang Xinhui New Materials Co., Ltd.;

[0064] Vinyl bromide polymer grade Wuhan Fuxinyuan Technology Co., Ltd.;

[0065] Dicumyl peroxide (DCP), Lanzhou Additive Factory;

[0066] n-Butyl lithium, 98% purity, Nanjing Tonglian Chemical Co., Ltd.;

[0067] Ethyl aluminum chloride, purity 98%, J&K Technology Co., Ltd.;

[0068] Other reagents are commercially available products.

[0069] (2) Analytical testing methods:

[0070] 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:

[0071]

[0072] 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.

[0073] 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 .

[0074] Determination of Mooney stress relaxation: Using the GT-7080S2 Mooney viscometer, refer to the method of GB / T1232.1-2000 and use a large rotor to measure at 125℃ (1+8). After the Mooney viscosity test is completed, the rotor is quickly stopped (within 0.1 seconds) and the decay of the Mooney viscosity value over time is recorded. The torque after the rotor stops (within 0.1 seconds) is set as 100%, and t 80 [The time it takes for the torque to decay by 80% (remaining 20%)] and X30 (the percentage of torque remaining after the rotor stops rotating for 30 seconds) describe the stress relaxation behavior of the rubber.

[0075] Vulcanization characteristics: tested according to GB / T 16584-1996.

[0076] Air tightness test: Use an automated air tightness tester to measure the air permeability according to ISO 2782:1995.

[0077] 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.

[0078] Tensile strength: Execute the method in standard GB / T528-2009.

[0079] Example 1

[0080] (1) Preparation of high molecular weight brominated grafting agent:

[0081] Preparation of a macromolecular brominating agent: First, in a 15 L stainless steel reactor with a jacket, argon was replaced twice, and 1000 g of cyclohexane, 1000 g of vinyl bromide, and 1.0 g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the reactor temperature reached 40°C, 0.5 g of DCP was added and the reaction was carried out for 2.0 hours. Then, 50 g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 30 minutes until no free monomer was left. After the reaction was completed, the reaction was washed and dried to obtain a macromolecular brominating agent.

[0082] b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon was replaced twice, and 3000g cyclohexane, 1000g isoprene, and 1.0g THF were added to the polymerization kettle in sequence. The temperature was raised to 40°C, and 12.1mmol n-butyl lithium was added to start the reaction for 50min; then 200g styrene was added to the polymerization kettle, the temperature was raised to 60°C, and the reaction was carried out for 40min to form -IR-PS- chain segments; finally, 400g of high molecular weight brominating agent was added to the polymerization kettle, the temperature was raised to 80°C, and the reaction was carried out for 50min until no free monomers were present. The glue was wet-coagulated and dried to obtain a high molecular weight brominated grafting agent (Mn was 27350, Mw / Mn was 1.57).

[0083] (2) Preparation of secondary brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged three times. 700g of chloromethane, 300g of cyclohexane, and 30g of a high-molecular-weight brominated grafting agent were added to the reactor and stirred for 30 minutes until completely dissolved. Then, when the temperature was lowered to -60°C, 500g of chloromethane, 450g of isobutylene, and 20g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -90°C. Then, 100g of chloromethane, 1.55g of sesquiethylaluminum chloride, and 0.016g of HCl were mixed and aged at -85°C for 20 minutes. The mixture was then added to the polymerization system and stirred for 1.0 hour. Finally, 25g of methanol was added, the product was discharged, condensed, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0084] Example 2

[0085] (1) Preparation of high molecular weight brominated grafting agent:

[0086] Preparation of a macromolecular brominating agent: First, in a 15 L stainless steel reactor with a jacket, the atmosphere was replaced with argon twice. 1200 g of cyclohexane, 1000 g of vinyl bromide, and 1.4 g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and heated. When the reactor temperature reached 43°C, 0.8 g of DCP was added and the reaction was carried out for 2.4 hours. Then, 55 g of isoprene was added to the polymerization reactor for end-capping. The reaction was carried out for 34 minutes until no free monomer was present. After completion of the reaction, the reactor was washed and dried to obtain a macromolecular brominating agent.

[0087] b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon was replaced twice, and 3200g of cyclohexane, 1000g of isoprene, and 1.3g of THF were added to the polymerization kettle in sequence. The temperature was raised to 42°C, and 14.3mmol of n-butyl lithium was added to start the reaction for 53min; then 220g of styrene was added to the polymerization kettle, the temperature was raised to 62°C, and the reaction was carried out for 43min to form -IR-PS- chain segments; finally, 430g of high molecular weight brominating agent was added to the polymerization kettle, the temperature was raised to 80°C, and the reaction was carried out for 55min until no free monomers were present. The glue was wet-coagulated and dried to obtain a high molecular weight brominated grafting agent (Mn was 29120, Mw / Mn was 1.74).

[0088] (2) Preparation of secondary brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged three times. 500g of chloromethane, 500g of cyclohexane, and 28g of a high molecular weight brominated grafting agent were added to the reactor and stirred for 35 minutes until completely dissolved. Then, when the temperature was lowered to -64°C, 550g of chloromethane, 455g of isobutylene, and 17g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -91°C. Then, 110g of chloromethane, 1.71g of sesquiethylaluminum chloride, and 0.056g of HCl were mixed and aged at -87°C for 22 minutes. The mixture was then added to the polymerization system and stirred for 1.6 hours. Finally, 30g of methanol was added. The product was discharged, condensed, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0089] Example 3

[0090] (1) Preparation of high molecular weight brominated grafting agent:

[0091] Preparation of a macromolecular brominating agent: First, in a 15 L stainless steel reactor with a jacket, argon was replaced three times, and 1400 g of cyclohexane, 1000 g of vinyl bromide, and 1.8 g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the reactor temperature reached 48°C, 1.0 g of DCP was added and the reaction was carried out for 2.7 hours. Then, 60 g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 38 minutes until no free monomer was left. After completion of the reaction, the reaction was washed and dried to obtain a macromolecular brominating agent.

[0092] b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon was replaced three times, and 3400g of cyclohexane, 1000g of isoprene, and 1.6g of THF were added to the polymerization kettle in sequence. The temperature was raised to 44°C, and 15.2mmol of n-butyl lithium was added to start the reaction for 56min; then 230g of styrene was added to the polymerization kettle, the temperature was raised to 65°C, and the reaction was carried out for 48min to form -IR-PS- chain segments; finally, 450g of high molecular weight brominating agent was added to the polymerization kettle, the temperature was raised to 82°C, and the reaction was carried out for 60min until no free monomers were present. The glue was wet-coagulated and dried to obtain a high molecular weight brominated grafting agent (Mn was 32540, Mw / Mn was 1.91).

[0093] (2) Preparation of secondary brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged four times. 300g of chloromethane, 500g of cyclohexane, and 25g of a high molecular weight brominated grafting agent were added to the reactor and stirred for 35 minutes until completely dissolved. Then, when the temperature was lowered to -68°C, 600g of chloromethane, 459g of isobutylene, and 16g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -92°C. Then, 120g of chloromethane, 2.73g of sesquiethylaluminum chloride, and 0.065g of HCl were mixed and aged at -88°C for 24 minutes. The mixture was then added to the polymerization system and stirred for 1.9 hours. Finally, 35g of methanol was added, the product was discharged, condensed, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0094] Example 4

[0095] (1) Preparation of high molecular weight brominated grafting agent:

[0096] Preparation of a macromolecular brominating agent: First, in a 15 L stainless steel reactor with a jacket, argon was replaced three times, and 1600 g of cyclohexane, 1000 g of vinyl bromide, and 2.0 g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the reactor temperature reached 50°C, 1.3 g of DCP was added and the reaction was carried out for 3.0 hours. Then, 70 g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 40 minutes until no free monomer was left. After completion of the reaction, the reaction was washed and dried to obtain a macromolecular brominating agent.

[0097] b. Preparation of a high molecular weight brominated grafting agent: First, in a 15 L stainless steel reactor with a jacket, argon was replaced three times, and 3600 g of cyclohexane, 1000 g of isoprene, and 2.0 g of THF were added to the polymerization kettle in sequence. The temperature was raised to 46° C., and 16.5 mmol of n-butyl lithium was added to start the reaction for 59 minutes; then 240 g of styrene was added to the polymerization kettle, the temperature was raised to 66° C., and the reaction was carried out for 50 minutes to form -IR-PS- segments; finally, 480 g of a high molecular weight brominating agent was added to the polymerization kettle, the temperature was raised to 83° C., and the reaction was carried out for 65 minutes until no free monomers were present. The glue was wet-coagulated and dried to obtain a high molecular weight brominated grafting agent (Mn was 37140, Mw / Mn was 2.21).

[0098] (2) Preparation of secondary brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged four times. 330g of chloromethane, 470g of cyclohexane, and 22g of a high molecular weight brominated grafting agent were added to the reactor and stirred for 35 minutes until completely dissolved. Then, when the temperature was lowered to -68°C, 700g of chloromethane, 464g of isobutylene, and 14g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -94°C. Then, 130g of chloromethane, 3.56g of sesquiethylaluminum chloride, and 0.075g of HCl were mixed and aged at -90°C for 26 minutes. The mixture was then added to the polymerization system and stirred for 2.0 hours. Finally, 40g of methanol was added. The product was discharged, condensed, washed, and dried to obtain a brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0099] Example 5

[0100] (1) Preparation of high molecular weight brominated grafting agent:

[0101] Preparation of a macromolecular brominating agent: First, in a 15 L stainless steel reactor with a jacket, argon was replaced three times, and 1800 g of cyclohexane, 1000 g of vinyl bromide, and 2.3 g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the reactor temperature reached 52° C., 1.6 g of DCP was added and the reaction was carried out for 3.5 hours. Then, 80 g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 42 minutes until no free monomer was left. After completion of the reaction, the reaction was washed and dried to obtain a macromolecular brominating agent.

[0102] b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon was replaced three times, and 3700g of cyclohexane, 1000g of isoprene, and 2.2g of THF were added to the polymerization kettle in sequence. The temperature was raised to 47°C, and 17.7mmol of n-butyllithium was added to start the reaction for 62min; then 260g of styrene was added to the polymerization kettle, the temperature was raised to 67°C, and the reaction was carried out for 52min to form -IR-PS- chain segments; finally, 500g of high molecular weight brominating agent was added to the polymerization kettle, the temperature was raised to 84°C, and the reaction was carried out for 70min until no free monomers were present. The glue was wet-coagulated and dried to obtain a high molecular weight brominated grafting agent (Mn was 40260, Mw / Mn was 2.35).

[0103] (2) Preparation of secondary brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged four times. 300g of chloromethane, 200g of cyclohexane, and 18g of a high molecular weight brominated grafting agent were added to the reactor and stirred for 35 minutes until completely dissolved. Then, when the temperature was lowered to -68°C, 800g of chloromethane, 469g of isobutylene, and 13g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -96°C. Then, 135g of chloromethane, 3.91g of sesquiethylaluminum chloride, and 0.086g of HCl were mixed and aged at -91°C for 27 minutes. The mixture was then added to the polymerization system and stirred for 2.3 hours. Finally, 43g of methanol was added. The product was discharged, condensed, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0104] Example 6

[0105] (1) Preparation of high molecular weight brominated grafting agent:

[0106] Preparation of a macromolecular brominating agent: First, in a 15 L stainless steel reactor with a jacket, argon was replaced four times, and 2000 g of cyclohexane, 1000 g of vinyl bromide, and 3.0 g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the reactor temperature reached 60°C, 2.0 g of DCP was added and the reaction was carried out for 4.0 hours. Then, 100 g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 50 minutes until no free monomer was left. After completion of the reaction, the reactor was washed and dried to obtain a macromolecular brominating agent.

[0107] b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon was replaced four times, and 4000g of cyclohexane, 1000g of isoprene, and 3.0g of THF were added to the polymerization kettle in sequence. The temperature was raised to 50°C, and 19.2mmol of n-butyl lithium was added to start the reaction for 70min; then 300g of styrene was added to the polymerization kettle, the temperature was raised to 70°C, and the reaction was carried out for 60min to form -IR-PS- chain segments; finally, 600g of high molecular weight brominating agent was added to the polymerization kettle, the temperature was raised to 85°C, and the reaction was carried out for 80min until no free monomers were present. The glue was wet-coagulated and dried to obtain a high molecular weight brominated grafting agent (Mn was 44650, Mw / Mn was 2.64).

[0108] (2) Preparation of secondary brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged five times. 350g of chloromethane, 150g of cyclohexane, and 15g of a high molecular weight brominated grafting agent were added to the reactor and stirred for 35 minutes until completely dissolved. Then, when the temperature was lowered to -68°C, 1000g of chloromethane, 475g of isobutylene, and 10g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -100°C. Then, 150g of chloromethane, 4.52g of sesquiethylaluminum chloride, and 0.098g of HCl were mixed and aged at -95°C for 30 minutes. The mixture was then added to the polymerization system and stirred for 3.0 hours. Finally, 50g of methanol was added, the product was discharged, condensed, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0109] Example 7

[0110] (1) Preparation of high molecular weight brominated grafting agent:

[0111] Preparation of a macromolecular brominating agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced four times, and 2000g of hexane, 1000g of vinyl bromide, and 2.6g of tert-tetradecane mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the reactor temperature reached 55°C, 1.8g of DTBP was added and the reaction was carried out for 3.7 hours. Then, 90g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 45 minutes until no free monomer was present. After completion of the reaction, the reaction was washed and dried to obtain the prepared macromolecular brominating agent.

[0112] b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon was replaced four times, and 3800g of hexane, 1000g of isoprene, and 2.8g of anisole were added to the polymerization kettle in sequence. The temperature was raised to 48°C, and 18.5mmol of dodecyllithium was added to start the reaction for 67min; then 290g of styrene was added to the polymerization kettle, the temperature was raised to 68°C, and the reaction was carried out for 58min to form -IR-PS- chain segments; finally, 550g of high molecular weight brominating agent was added to the polymerization kettle, the temperature was raised to 88°C, and the reaction was carried out for 75min until no free monomers were present. The glue was wet-coagulated and dried to obtain a high molecular weight brominated grafting agent (Mn was 42800, Mw / Mn was 2.51).

[0113] (2) Preparation of secondary brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was purged five times. 330g of ethylene dichloride, 130g of hexane, and 16g of a high molecular weight brominated grafting agent were added to the reactor and stirred for 33 minutes until completely dissolved. Then, when the temperature was lowered to -68°C, 1000g of ethylene dichloride, 473g of isobutylene, and 12g of isoprene were added in sequence and stirred until the polymerization system temperature dropped to -100°C. Then, 150g of ethylene dichloride, 4.45g of diisobutylaluminum monochloride, and 0.095g of HCl were mixed and aged at -95°C for 30 minutes. The mixture was then added to the polymerization system and stirred for 2.6 hours. Finally, 46g of ethanol was added, the product was discharged, condensed, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared. The test properties are shown in Table 1.

[0114] Comparative Example 1

[0115] (1) Preparation of high molecular weight brominated grafting agent:

[0116] Preparation of a macromolecular brominating agent: Other conditions were the same as in Example 1, except that monomer isoprene was not added for end-capping. Specifically, in a 15 L stainless steel reactor with a jacket, argon was replaced twice. 1000 g of cyclohexane, 1000 g of vinyl bromide, and 1.0 g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the reactor temperature reached 40° C., 0.5 g of DCP was added and the reaction was carried out for 30 min until no free monomer was present. After completion of the reaction, the reactor was washed and dried to obtain macromolecular brominating agent-1.

[0117] b. Preparation of a high molecular weight brominated grafting agent: Other conditions were the same as in Example 1, except that: instead of adding a high molecular weight brominating agent during the synthesis, a high molecular weight brominating agent-1 was added in an amount of 400 g. That is, first, in a 15 L stainless steel reactor with a jacket, argon was replaced twice, and 3000 g of cyclohexane, 1000 g of isoprene, and 1.0 g of THF were added to the polymerization kettle in sequence. The temperature was raised to 40° C., and 12.1 mmol of n-butyl lithium was added to initiate the reaction for 50 min. Then, 200 g of styrene was added to the polymerization kettle, the temperature was raised to 60° C., and the reaction was carried out for 40 min to form -IR-PS- segments. Finally, 400 g of the high molecular weight brominating agent-1 was added to the polymerization kettle, the temperature was raised to 80° C., and the reaction was carried out for 50 min until no free monomers were present. The glue was subjected to wet coagulation and drying to obtain a high molecular weight brominated grafting agent-1 (Mn was 26120, Mw / Mn was 1.43).

[0118] (2) Preparation of secondary brominated branched butyl rubber: Other conditions were the same as those in Example 1, except that: in the preparation of secondary brominated branched butyl rubber, instead of adding a high molecular weight brominated grafting agent, a high molecular weight brominated grafting agent-1 was added in an amount of 30 g. That is, first, in a 4 L stainless steel reactor with a jacket, nitrogen was passed through and replaced three times, and 700 g of monochloromethane, 300 g of cyclohexane, and high molecular weight brominated grafting agent-1 were added to the polymerization reactor. 30g of methyl chloroform was stirred and dissolved for 30 minutes until completely dissolved. Then, when the temperature was lowered to -60°C, 500g of methyl chloroform, 450g of isobutylene, and 20g of isoprene were added sequentially and stirred until the polymerization system temperature dropped to -90°C. Then, 100g of methyl chloroform, 1.55g of sesquiethylaluminum chloride, and 0.016g of HCl were mixed and aged at -85°C for 20 minutes before being added to the polymerization system and stirred for 1.0 hour. Finally, 25g of methanol was added, the product was discharged, coagulated, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard specimens were prepared. The test properties are shown in Table 1.

[0119] Comparative Example 2

[0120] (1) Preparation of high molecular weight brominated grafting agent:

[0121] a. Preparation of macromolecular brominating agent: same as in Example 2.

[0122] b. Preparation of a high molecular weight brominated grafting agent: Other conditions were the same as those in Example 2, except that no macromolecular brominating agent was added during the preparation of the high molecular weight brominated grafting agent. Instead, a low molecular weight vinyl bromide was directly added in an amount of 430 g. That is, first, in a 15 L stainless steel reactor with a jacket, argon was replaced twice, and 3200 g of cyclohexane, 1000 g of isoprene, and 1.3 g of THF were added to the polymerization kettle in sequence. The temperature was raised to 42° C., and 14.3 mmol of n-butyl lithium was added to initiate the reaction for 53 min. Then, 220 g of styrene was added to the polymerization kettle, the temperature was raised to 62° C., and the reaction was carried out for 43 min to form -IR-PS- segments. Finally, 430 g of vinyl bromide was added to the polymerization kettle, the temperature was raised to 80° C., and the reaction was carried out for 55 min until no free monomers were present. The gel was subjected to wet coagulation and drying to obtain a high molecular weight brominated grafting agent-2 (Mn: 26720, Mw / Mn: 1.51).

[0123] (2) Preparation of secondary brominated branched butyl rubber: Other conditions were the same as those in Example 2, except that: in the preparation process of secondary brominated branched butyl rubber, instead of adding a high molecular weight brominated grafting agent, a high molecular weight brominated grafting agent-2 was added in an amount of 28 g, namely: first, in a 4 L stainless steel reactor with a jacket, nitrogen was purged three times, 500 g of chloromethane, 500 g of cyclohexane, and 28 g of high molecular weight brominated grafting agent-2 were added to the polymerization reactor, and stirred and dissolved for 35 minutes until completely dissolved; then, when the temperature was lowered to -64°C, 550 g of chloromethane, 455 g of isobutylene, and 17 g of isoprene were added in sequence, and stirred and mixed until the polymerization system temperature dropped to -91°C, and then 110 g of chloromethane, 1.71 g of sesquiethylaluminum chloride and HCl were added. After mixing and aging for 22 minutes at -87°C, 0.056g of the butyl rubber was added to the polymerization system and stirred for 1.6 hours. Finally, 30g of methanol was added, and the product was coagulated, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared, and the test properties are shown in Table 1.

[0124] Comparative Example 3

[0125] (1) Preparation of high molecular weight brominated grafting agent:

[0126] a. Preparation of macromolecular brominating agent: same as Example 3.

[0127] b. Preparation of a high molecular weight brominated grafting agent: Other conditions were the same as in Example 3, except that monomer styrene was not added during the preparation of the high molecular weight brominated grafting agent. Specifically, in a 15 L stainless steel reactor with a jacket, argon was replaced three times, and 3400 g of cyclohexane, 1000 g of isoprene, and 1.6 g of THF were added to the polymerization kettle in sequence. The temperature was raised to 44° C., and 15.2 mmol of n-butyl lithium was added to initiate the reaction for 56 min to form -IR- segments. Finally, 450 g of a high molecular weight brominating agent was added to the polymerization kettle, the temperature was raised to 82° C., and the reaction was continued for 60 min until no free monomers were present. The gel was then subjected to wet coagulation and drying to obtain a high molecular weight brominated grafting agent-3 (Mn: 28620, Mw / Mn: 1.42).

[0128] (2) Preparation of secondary brominated branched butyl rubber: Other conditions are the same as those in Example 3, except that: in the preparation process of secondary brominated branched butyl rubber, instead of adding a high molecular weight brominated grafting agent, a high molecular weight brominated grafting agent-3 is added in an amount of 25 g, that is: first, in a 4L stainless steel reactor with a jacket, nitrogen is replaced 4 times, 300 g of chloromethane, 500 g of cyclohexane, and 25 g of high molecular weight brominated grafting agent-3 are added to the polymerization reactor, and stirred and dissolved for 35 minutes until completely dissolved; then, when the temperature is lowered to -68°C, 600 g of chloromethane, 459 g of isobutylene, and 16 g of isoprene are added in sequence, and stirred and mixed until the polymerization system temperature drops to -92°C, and then 120 g of chloromethane, 2.73 g of sesquiethylaluminum chloride and HCl are added. After mixing and aging at -88°C for 24 minutes, 0.065g of the butyl rubber was added to the polymerization system and stirred for 1.9 hours. Finally, 35g of methanol was added, and the product was coagulated, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared, and the test properties are shown in Table 1.

[0129] Comparative Example 4

[0130] (1) Preparation of secondary brominated branched butyl rubber: Other conditions were the same as those in Example 4, except that: in the preparation of secondary brominated branched butyl rubber, a high molecular weight brominated grafting agent was not added, but a small molecular weight brominating agent, vinyl bromide, was added in an amount of 22 g. That is: first, in a 4 L stainless steel reactor with a jacket, nitrogen was purged 4 times, 330 g of chloromethane, 470 g of cyclohexane, and 22 g of vinyl bromide were added to the polymerization reactor, and stirred and dissolved for 35 minutes until completely dissolved; then, when the temperature was lowered to -68°C, 700 g of chloromethane, 464 g of isobutylene, and 14 g of isoprene were added in sequence, and stirred and mixed until the polymerization system temperature dropped to -94°C. Then, 130 g of chloromethane, 3.56 g of sesquiethylaluminum chloride, and HCl were added. After mixing and aging for 26 minutes at -90°C, 0.075g of the butyl rubber was added to the polymerization system and stirred for 2 hours. Finally, 40g of methanol was added, and the product was coagulated, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared, and the test properties are shown in Table 1.

[0131] Comparative Example 5

[0132] (1) Preparation of high molecular weight brominated grafting agent:

[0133] a. Preparation of macromolecular brominating agent: same as Example 5.

[0134] b. Preparation of high molecular weight brominated grafting agent: same as Example 5.

[0135] (2) Preparation of secondary brominated branched butyl rubber: Other conditions were the same as those in Example 5, except that: in the preparation of secondary brominated branched butyl rubber, instead of adding a high molecular weight brominated grafting agent, a macromolecular brominating agent was added in an amount of 18 g, namely: first, in a 4 L stainless steel reactor with a jacket, nitrogen was purged 4 times, 300 g of chloromethane, 200 g of cyclohexane, and 18 g of macromolecular brominating agent were added to the polymerization reactor, and stirred and dissolved for 35 minutes until completely dissolved; then, when the temperature was lowered to -68°C, 800 g of chloromethane, 469 g of isobutylene, and 13 g of isoprene were added in sequence, and stirred and mixed until the polymerization system temperature dropped to -96°C, and then 135 g of chloromethane, 3.91 g of sesquiethylaluminum chloride and HCl were added. After mixing and aging for 27 minutes at -91°C, 0.086g of the butyl rubber was added to the polymerization system and stirred for 2.3 hours. Finally, 43g of methanol was added, and the product was coagulated, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared, and the test properties are shown in Table 1.

[0136] Comparative Example 6

[0137] (1) Preparation of high molecular weight brominated grafting agent:

[0138] a. Preparation of macromolecular brominating agent: same as Example 6.

[0139] b. Preparation of high molecular weight brominated grafting agent: same as Example 6.

[0140] (2) Preparation of secondary brominated branched butyl rubber: Other conditions were the same as those in Example 6, except that 5.0 g of the high molecular weight brominated grafting agent was added during the preparation of the secondary brominated branched butyl rubber. Specifically, 350 g of methyl chloride, 150 g of cyclohexane, and 5.0 g of the high molecular weight brominated grafting agent were added to a 4 L stainless steel reactor with a jacket, and the mixture was replaced with nitrogen 5 times. The mixture was stirred and dissolved for 35 minutes until it was completely dissolved. The mixture was then cooled to -68°C, and 1000 g of methyl chloride, 475 g of isobutylene, and 10 g of isoprene were added in sequence. The mixture was stirred and mixed until the temperature of the polymerization system dropped to -100°C. Then, 150 g of methyl chloride, 4.52 g of sesquiethylaluminum chloride, and HCl were added. 0.098g of the butyl rubber was mixed and aged at -95°C for 30 minutes before being added to the polymerization system and stirred for 3.0 hours. Finally, 50g of methanol was added, the product was coagulated, washed, and dried to obtain the brominated branched butyl rubber product. Sampling and Analysis: Standard samples were prepared, and the test properties are shown in Table 1.

[0141] Table 1 Properties of secondary brominated branched butyl rubber

[0142]

[0143]

[0144] Note: 10 The scorch time reflects the size of the scorch safety window; t 90 The positive vulcanization time reflects the speed of vulcanization.

[0145] As shown in Table 1, the brominated branched butyl rubber of the present invention has a wide molecular weight distribution, a high vulcanization rate and a low Mooney stress relaxation time, exhibiting good processing and vulcanization characteristics while maintaining high tensile strength and good air tightness.

[0146] 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 a secondary brominated branched butyl rubber, the method comprising the following steps: S1: adding a high molecular weight brominated grafting agent to a mixed solvent and stirring thoroughly until the high molecular weight 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 a secondary brominated branched butyl rubber; It is characterized in that the preparation method of the polymer brominated grafting agent specifically comprises the following steps: a. Preparation of a macromolecular brominating agent: First, based on 100 parts of vinyl bromide by weight, 100-200 parts of solvent, 100 parts of vinyl bromide, and 0.1-0.3 parts of a molecular weight regulator are added sequentially to a reactor after inert gas substitution, stirred and mixed, and heated. When the reactor temperature reaches 40-60° C., 0.05-0.2 parts of a first initiator are added and reacted for 2.0-4.0 hours until the vinyl bromide monomer conversion reaches 100%. Then, 5-10 parts of isoprene are added to the reactor for end-capping, and the reaction is carried out for 30-50 minutes until no free monomer is left. After the reaction is completed, the mixture is washed and dried to obtain a macromolecular brominating agent. b. Preparation of a high molecular weight brominated grafting agent: First, to a reactor purged with inert gas, 300 wt% to 400 wt% of a solvent, 100 wt% of isoprene, and 0.1 wt% to 0.3 wt% of a structure modifier are added in sequence, based on 100% by weight of the reaction monomer isoprene. After heating to 40-50° C., a second initiator is added and reacted for 50-70 minutes. Then, 20 wt% to 30 wt% of styrene is added to the reactor, the temperature is raised to 60-70° C., and the reaction is carried out for 40-60 minutes to form -IR-PS- segments. Finally, 40 wt% to 60 wt% of a high molecular weight brominating agent is added to the reactor, the temperature is raised to 80-85° C., and the reaction is carried out for 50-80 minutes until no free monomer is present. After completion of the reaction, the reactor is subjected to wet coagulation and drying to obtain a high molecular weight brominated grafting agent. The number average molecular weight (Mn) of the high molecular weight brominated grafting agent is 27000-45000, and the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) is 1.57-2.

64.

2. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein In step S1, the mass ratio of the mixed solvent to the high molecular weight brominated grafting agent is 100-200:3-6; 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 secondary brominated branched butyl rubber according to claim 2, wherein The solvent is at least one of pentane, hexane, octane, heptane, cyclohexane, benzene, toluene, xylene and ethylbenzene.

4. The method for preparing secondary brominated branched butyl rubber according to claim 2, wherein The solvent is cyclohexane.

5. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein In step S2, the temperature is lowered to -60°C to -80°C; and the temperature is lowered again to -100°C to -90°C.

6. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein In step S2, the mass ratio of the diluent, isobutylene and isoprene is 100-200:90-95:2-4.

7. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein In step S3, the mass ratio of the diluent, the co-initiator and the terminator is 20-30:0.01-1.0:5-10.

8. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein The molecular weight regulator is at least one of tert-decyl mercaptan, tert-dodecyl mercaptan, tert-tetradecyl mercaptan, and tert-hexadecanethiol; The first initiator is an organic peroxide, selected from at least one of di-tert-butyl hydroperoxide, 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane, di-tert-butyl peroxide, and dicumyl peroxide; The structure regulator is a polar organic compound, and the polar organic compound is at least one selected from diethylene glycol dimethyl ether, tetrahydrofuran, ethyl ether, ethyl methyl ether, anisole, diphenyl ether, ethylene glycol dimethyl ether, and triethylamine.

9. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein The molecular weight regulator is tert-dodecyl mercaptan.

10. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein: The first initiator is dicumyl peroxide.

11. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein: The structure regulator is tetrahydrofuran.

12. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein: The second initiator is a hydrocarbon monolithium compound RLi, which is selected from one of n-butyllithium, sec-butyllithium, methylbutyllithium, phenylbutyllithium, naphthalenelithium, cyclohexyllithium, and dodecyllithium.

13. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein: The second initiator is n-butyl lithium.

14. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein: In the method for preparing the polymer brominated grafting agent, the solvents in step a and step b are independently selected from at least one of pentane, hexane, octane, heptane, cyclohexane, benzene, toluene, xylene and ethylbenzene.

15. The method for preparing secondary brominated branched butyl rubber according to claim 1, wherein: In the preparation method of the polymer brominated grafting agent, the solvent in step a and step b is cyclohexane.

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

18. The method for preparing secondary brominated 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 one of HCl, HF, HBr, H2SO4, H2CO3, H3PO4 and HNO3; and the molar ratio of the protonic acid to the alkyl aluminum halide is 0.01:1 to 0.1:

1.

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

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

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

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