CN116410413A - A kind of preparation method of secondary position brominated branched butyl rubber - Google Patents

Abstract

The invention discloses a preparation method of secondary brominated branched butyl rubber, which comprises the steps of adding a high molecular brominated grafting agent into a mixed solvent, and fully stirring until the high molecular brominated grafting agent is completely dissolved to obtain a mixed solution; cooling, sequentially adding a diluent, isobutene and isoprene into the mixed solution, fully stirring and mixing to obtain a polymerization reaction system, and cooling again; mixing and aging a diluent and a co-initiator, adding the mixture into a polymerization reaction system, fully stirring the mixture for reaction, adding a terminator, discharging, condensing, washing and drying to obtain secondary brominated and branched butyl rubber; the polymer brominated grafting agent is a linear block copolymer composed of isoprene, styrene and bromoethylene. The preparation method not only solves the problem of low stress relaxation rate of the butyl rubber in the processing process of the butyl rubber, but also maintains enough green rubber strength and good air tightness, and gives balance of physical and mechanical properties and vulcanization processing properties.

Description

A method for preparing secondary brominated branched butyl rubber

Technical Field

The invention relates to a method for preparing secondary brominated branched butyl rubber, in particular to a method for grafting butyl rubber with secondary brominated isoprene/styrene block copolymer.

Background Art

Butyl rubber (IIR) is a copolymer of isobutylene and a small amount of isoprene by cationic polymerization. It has excellent air tightness, damping, heat aging resistance, ozone resistance and weather resistance, and is widely used in the manufacture of inner tubes, airtight layers, vulcanization bladders and other fields of automobile tires, becoming one of the most important synthetic rubber varieties. However, the molecular chain of butyl rubber is mainly composed of carbon-carbon single bonds, with low unsaturation, and symmetrical arrangement of methyl substituents. It has the disadvantages of high crystallinity, poor flexibility of the molecular chain, slow stress relaxation rate, slow vulcanization speed, poor adhesion, and poor compatibility with other general rubbers. Therefore, butyl rubber is prone to excessive flow and deformation during processing, which has become a bottleneck for the expansion of butyl rubber materials.

At present, 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 with IIR, BIIR has the same excellent air tightness. The introduction of bromine atoms not only increases the polarity of the molecular chain and improves the adhesion with other rubbers, but also can be used with natural rubber, styrene-butadiene rubber and other unsaturated rubbers in any ratio. It also produces additional cross-linking points, which enhances the activity of the original double bonds, improves the vulcanization performance of the rubber, and makes the vulcanization speed faster and the vulcanization methods more diversified; the heat resistance is also improved. 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.

进行溴化反应、最后中和及产品回收得到溴化星形支化丁基橡胶。该工艺可以在溴化前将星形支化丁基橡胶中残余的支化剂溶解，防止其与溴化过程中产生的HBr副产物结合，从而提高中和效率，抑制TypeⅡ仲位结构向Type III伯位结构的异构化转变。CN112574333A provides a bromination process for star-branched butyl rubber, which comprises: a) dissolving the star-branched butyl rubber in aliphatic hydrocarbon to obtain a rubber solution; b) mixing the above-mentioned rubber solution with a branching agent and a scavenging agent ethanol to obtain a mixed solution; c) adding an oxidizing agent hydrogen peroxide and a brominating agent Br ₂ to the above-mentioned mixed solution, and the molar ratio of the bromine element to the 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 to prevent it from combining with the HBr by-product generated during the bromination process, thereby improving the neutralization efficiency and inhibiting the isomerization transformation from the Type II secondary structure to the Type III primary structure.

CN112011019A discloses a method for preparing a halogenated bimodal distribution star-branched butyl rubber, which adopts anionic polymerization technology to synthesize poly(styrene-conjugated diene) block polymer, and obtains a four-arm star-shaped block polymer by coupling with silicon tetrachloride; 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 reduced to below -60°C, the main initiator and the co-initiator are mixed and aged, and then added to the system, polymerized for 3 to 30 minutes under stirring, a terminator is added to terminate the reaction, the filling is steamed under reduced pressure, and the sample is vacuum dried; and then it is halogenated to obtain a halogenated bimodal distribution star-shaped branched butyl rubber. The bimodal distribution star-shaped branched butyl rubber prepared by this method has the characteristics of small Mooney stress relaxation and lower intrinsic viscosity, and exhibits good processing performance.

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, directly participates in cationic polymerization in a cationic polymerization system of a mixed solvent of methyl chloride/cyclohexane with a v:v ratio of 20-80/80-20 under the temperature condition of 0-100°C, and prepares star-branched polyisobutylene or butyl rubber products through the initiation of cationic polymerization by silyl chloride groups and the participation of unsaturated chains in grafting reaction.

CN 106749816A discloses a method for preparing brominated butyl rubber, which firstly uses n-alkane to dissolve butyl rubber, then uses specific organic bromides such as phenyltrimethylammonium tribromide, benzyltrimethylammonium tribromide, and dibromoisocyanuric acid as brominating agents, and uses _Br2 or HBr as bromination accelerators to carry out bromination reaction in a solvent to obtain brominated butyl rubber. The method inhibits the molecular rearrangement of secondary bromine in brominated butyl rubber to form quaternary bromine, and increases the secondary bromine structure content in brominated butyl rubber.

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 carbon cation polymerization in an initiator system of 2-chloro-2,4,4-trimethylpentane/titanium tetrachloride/proton scavenger.

公开了一种将丁基橡胶(Polysar-301)用环烷烃溶解，并通过液溴进行溴化后制备出了溴化丁基橡胶的方法,考察停留时间及反应温度对产物门尼黏度、不饱和度、溴含量及微观结构的影响。结果表明，停留时间在2min以内时其门尼黏度和不饱和度急剧下降，超过2min后的变化不大；升高反应温度会使门尼黏度下降，而对不饱和度影响较小。升高反应温度和延长停留时间不仅有利于产物中溴含量的增加，而且有利于其分子结构的重排，即存在由溴代仲位烯丙基构型向更稳定的溴代伯位烯丙基构型转移的现象。Synthetic Rubber Industry (2006, 29(4):

A method for preparing brominated butyl rubber by dissolving butyl rubber (Polysar-301) in cycloalkane and brominating it with liquid bromine is disclosed, and the effects of residence time and reaction temperature on the Mooney viscosity, unsaturation, bromine content and microstructure of the product are investigated. The results show that the Mooney viscosity and unsaturation drop sharply when the residence time is less than 2 minutes, and the change is not significant after exceeding 2 minutes; increasing the reaction temperature will reduce the Mooney viscosity, but have little effect on the unsaturation. Increasing the reaction temperature and extending the residence time are not only conducive to increasing the bromine content in the product, but also conducive to the rearrangement of its molecular structure, that is, there is a phenomenon of transfer from the brominated secondary allylic configuration to the more stable brominated primary allylic configuration.

In the above-mentioned prior art, the molecular weight distribution of the brominated butyl rubber obtained after the star-branched butyl rubber or butyl rubber is dissolved and brominated becomes larger, the stress relaxation rate increases, the vulcanization speed becomes faster, and good processability is shown. However, these methods still have certain limitations. In the bromination process of butyl rubber, hydrogen bromide is easily generated as a byproduct, which leads to the loss of the remaining bromine, reduces the utilization rate of bromine, and makes the isomerization of the rubber of Type II secondary structure in the brominated butyl rubber to Type III primary structure obvious, thereby affecting the processing performance of the brominated butyl rubber. At the same time, hydrogen bromide is very corrosive, resulting in the deterioration of the quality of the brominated butyl rubber, and is also easy to cause environmental pollution and human safety and health problems.

Summary of the invention

The purpose of the present invention is to provide a method for preparing secondary brominated branched butyl rubber. The preparation method uses a macromolecular brominating agent as a raw material, and the macromolecular brominating agent has anionic reaction activity; secondly, alkyl lithium is used as an initiator to synthesize a high molecular bromination grafting agent from isoprene, styrene and the macromolecular brominating agent; finally, the high molecular bromination grafting agent, isobutylene and isoprene are subjected to cationic polymerization under a catalytic system of alkyl aluminum halide and protonic acid to prepare a method for brominated branched butyl rubber. The present invention uses a brominating agent containing an unsaturated double bond to prepare brominated branched butyl rubber through addition polymerization, rather than the ion substitution reaction in the prior art. This method avoids the molecular rearrangement of secondary bromine in brominated butyl rubber to form primary bromine due to the production of byproduct hydrogen bromide, solves the problem of structural stability of secondary bromine in brominated branched butyl rubber, and improves the vulcanization rate of 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 sufficient raw rubber strength and good air tightness of butyl rubber are maintained, giving butyl rubber a balance between physical and mechanical properties and vulcanization processing performance.

Unless otherwise specified, the "%" described in the present invention refers to mass percentage.

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:

S1: adding the polymer brominated grafting agent to the mixed solvent, and stirring until the polymer brominated grafting agent is completely dissolved to obtain a mixed solution;

S2: cooling, adding a diluent, isobutylene and isoprene to the mixed solution of step S1 in sequence, stirring and mixing sufficiently to obtain a polymerization reaction system, and cooling 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 sufficiently for reaction, adding a terminator, condensing the discharged material, washing, and drying them to obtain a secondary brominated branched butyl rubber;

It is characterized in that the macromolecular 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:

Among them, 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 27000-45000, and the ratio of the weight average molecular weight to the number average molecular weight (Mw/Mn) is 1.57-2.64.

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.

In the method for preparing secondary brominated 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.

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.

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.

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.

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.

In the method for preparing 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.

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.

The preparation method of the secondary brominated branched butyl rubber of the present invention, the preparation method of the polymer brominated grafting agent specifically comprises the following steps:

a. Preparation of macromolecular brominating agent: based on 100 parts of vinyl bromide, firstly, into a reactor replaced with inert gas, 100-200 parts of solvent, 100 parts of vinyl bromide, and 0.1-0.3 parts of molecular weight regulator are added in sequence, stirred, mixed, and heated. When the temperature of the reactor reaches 40-60°C, 0.05-0.2 parts of the first initiator are added, and the reaction is carried out for 2.0-4.0 hours, and the vinyl bromide monomer conversion rate 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 macromolecular brominating agent is obtained by washing and drying.

b. Preparation of high molecular weight brominated grafting agent: based on 100% of the total weight of the reaction monomers, first, 300 wt% to 400 wt% of solvent, 100 wt% of isoprene, and 0.1 wt% to 0.3 wt% of structure regulator are added to the reactor after inert gas replacement in sequence, and after the temperature is raised to 40 to 50° C., a second initiator is added to react for 50 to 70 min; then, 20 wt% to 30 wt% of styrene is added to the reactor, the temperature is raised to 60 to 70° C., and the reaction is carried out for 40 to 60 min to form -IR-PS- segments; finally, 40 wt% to 60 wt% of a macromolecular bromizing agent is added to the reactor, the temperature is raised to 80 to 85° C., and the reaction is carried out for 50 to 80 min until no free monomers are present. After the reaction is completed, the high molecular weight brominated grafting agent is obtained by wet condensation and drying.

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-hexadecyl mercaptan, preferably tert-dodecyl mercaptan.

The method for preparing secondary brominated branched butyl rubber of the present invention, wherein 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 diisopropylbenzene peroxide (DCP), preferably DCP.

The method for preparing secondary brominated branched butyl rubber of the present invention, wherein the structure regulator is a polar organic compound, which produces a solvation effect in the polymerization system, can adjust the reactivity ratio of styrene and isoprene, and make the two copolymerize randomly. This type of 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).

The preparation method of the secondary brominated branched butyl rubber of the present invention, the second initiator is a hydrocarbon monolithium compound, i.e., RLi, wherein R is a saturated aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group or a composite group of the above groups containing 1 to 20 carbon atoms. The hydrocarbon monolithium compound is selected from one of n-butyl lithium, sec-butyl lithium, methyl butyl lithium, phenyl butyl lithium, naphthalene lithium, cyclohexyl lithium and dodecyl lithium, preferably n-butyl lithium. The amount of the second initiator added is determined by the molecular weight of the designed polymer.

The polymerization reaction in the preparation method of the secondary brominated 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 the dissolution process are both completed in a hydrocarbon solvent. The solvent of the present invention is a hydrocarbon solvent, and the hydrocarbon solvent includes straight-chain 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, preferably cyclohexane.

In the preparation method of the secondary brominated branched butyl rubber of the present invention, the diluent is a halogenated alkane; the halogen atom 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 selected from at least one of monochloromethane, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloropropane, heptachloropropane, monofluoromethane, difluoromethane, tetrafluoroethane, carbon hexafluoride and fluorobutane, preferably monochloromethane.

The preparation method of secondary brominated branched butyl rubber of the present invention, the co-initiator is composed of alkyl aluminum halide and protonic acid in different proportions. The alkyl aluminum halide is selected from at least one of diethyl aluminum monochloride, diisobutyl aluminum monochloride, methyl aluminum dichloride, sesquiethyl aluminum chloride, sesquiisobutyl aluminum chloride, n-propyl aluminum dichloride, isopropyl aluminum dichloride, dimethyl aluminum chloride and ethyl aluminum chloride, preferably sesquiethyl aluminum 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 .

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.

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

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

(1) Preparation of polymer brominated grafting agent:

a. Preparation of macromolecular brominating agent: based on 100 parts of vinyl bromide, firstly, in a 15L stainless steel reactor with a jacket, inert gas is replaced 2 to 4 times, 100 to 200 parts of solvent, 100 parts of vinyl bromide, and 0.1 to 0.3 parts of molecular weight regulator are added to the reactor in sequence, stirred, mixed, and heated. When the temperature of the reactor reaches 40 to 60°C, 0.05 to 0.2 parts of the first initiator are added and reacted for 2.0 to 4.0 hours, at which time the vinyl bromide monomer conversion rate reaches 100%; then 5 to 10 parts of isoprene are added to the reactor for end-capping, and the reaction is carried out for 30 to 50 minutes until no free monomer is present. After the reaction is completed, the macromolecular brominating agent is obtained by washing and drying.

b. Preparation of high molecular weight brominated grafting agent: Based on 100% of the mass of the reaction monomer isoprene, first, in a 15L stainless steel reactor with a jacket, argon gas is replaced 2 to 4 times, and 300wt% to 400wt% of solvent, 100wt% of isoprene, and 0.1wt% to 0.3wt% of structure regulator are added to the reactor in sequence, and after the temperature is raised to 40 to 50°C, a second initiator is added to react for 50 to 70 minutes; then 20wt% to 30wt% of styrene is added to the reactor, the temperature is raised to 60 to 70°C, and the reaction is carried out for 40 to 60 minutes to form -IR-PS- segments; finally, 40wt% to 60wt% of a macromolecular brominating agent is added to the reactor, the temperature is raised to 80 to 85°C, and the reaction is carried out for 50 to 80 minutes until no free monomer is present. After the reaction is completed, the high molecular weight brominated grafting agent is obtained by wet condensation and drying.

(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 the diluent and 100wt% of the solvent are added in sequence. The invention relates to a method for preparing a branched butyl rubber product comprising: preparing a first polymerization product comprising: ...

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:

Wherein: IR is isoprene homopolymer block; PS is styrene homopolymer block; m and n are the number of repeating units. The number average molecular weight (Mn) of the high molecular brominated grafting agent is 27000-45000, and the molecular weight distribution (Mw/Mn) is 1.57-2.64.

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

The polymer brominated grafting agent of the present invention mainly plays three roles:

On the one hand, it plays a role in preventing the rearrangement of the bromine structure in the brominated branched butyl rubber, mainly because the secondary bromine structure in the high molecular weight brominated grafting agent is generated by addition polymerization rather than ion substitution in the prior art, thereby avoiding the generation of by-product hydrogen bromide (HBr), 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.

Secondly, it plays a role in improving the utilization rate of bromine element. 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, and then participates in an anion reaction. HBr will not be 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 element in brominated branched butyl rubber. At the same time, the alkali washing recovery process of the by-product HBr is omitted, thereby shortening the process flow and reducing production costs.

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, which have the characteristics of high rigidity and large steric hindrance. It can avoid the problem of molecular weight distribution of butyl rubber becoming wider due to branching, thereby causing the strength and air tightness of butyl rubber to decrease.

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

In summary, the present invention has the following beneficial effects:

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 in the prior art, thereby avoiding the generation of by-product hydrogen bromide (HBr) 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 speed, and solving the problem of slow vulcanization speed of butyl rubber during processing.

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. HBr will not be generated during the entire reaction process, thereby avoiding the loss of the 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.

3. The polymer brominated grafting agent of the present invention does not generate by-product HBr during the entire reaction process, which reduces the harm to humans and the environment and eliminates the alkali washing and recovery process of the by-product HBr, thereby shortening the process and reducing production costs.

4. The high molecular weight brominated grafting agent of the present invention contains a [-PS-IR-]m chain segment, and 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, which can avoid the problem of a widening of the molecular weight distribution of butyl rubber due to branching, thereby causing a decrease in the strength and air tightness of butyl rubber.

5. The polymer brominated grafting agent of the present invention is a new type of safe and environmentally friendly compound without air pollutants (VOC) and by-product HBr emissions. Its preparation method is green and environmentally friendly, the process flow is short, the bromine structure is controllable, it shows good processability, and it is suitable for industrial production.

DETAILED DESCRIPTION

The following is a detailed description of the embodiments of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and process are given, but the protection scope of the present invention is not limited to the following embodiments. The experimental methods in the following embodiments without specifying specific conditions are usually carried out under conventional conditions.

(1) Source of raw materials:

Styrene, polymer grade PetroChina Lanzhou Petrochemical Company;

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

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

Dicumyl peroxide (DCP), Lanzhou Additive Factory;

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

Sesquiethylaluminum chloride, purity 98%, J&K Technology Co., Ltd.;

Other reagents are commercially available products.

(2) Analytical testing methods:

Determination of bromine content: Weigh 10 mg of sample and use Q600 TG/DTG thermogravimetric analyzer, with a heating rate of 10℃/min, in a nitrogen atmosphere with a flow rate of 50mL/min to thermally degrade the sample. The first stage of thermal degradation is the debromination of the bromine-containing units of the sample to form HBr, and then the bromine content (X) in the sample is inferred from the percentage of HBr removed. The calculation formula is as follows:

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.

Molecular weight and its distribution were determined by using a 2414 gel permeation chromatograph (GPC) produced by Waters, USA. The polystyrene standard was 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 .

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°C (1+8). Stress relaxation determination 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 taken for the torque to decay by 80% (remaining 20%)] and X30 (the remaining torque percentage after the rotor stops for 30 seconds) are used to describe the stress relaxation behavior of rubber.

Vulcanization characteristics: Tested according to GB/T 16584-1996.

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

The test gas was N ₂ , the test temperature was 23° C., and the test sample was a circular sea piece with a diameter of 8 cm and a thickness of 1 mm.

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

Example 1

(1) Preparation of polymer brominated grafting agent:

a. Preparation of macromolecular brominating agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced twice, and 1000g of cyclohexane, 1000g of vinyl bromide, and 1.0g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the temperature of the reactor reached 40°C, 0.5g of DCP was added and reacted for 2.0hr; then 50g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 30min until no free monomer was present. After the reaction was completed, the macromolecular brominating agent was obtained by washing and drying.

b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas 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- 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 colloid was wet condensed and dried to obtain a high molecular weight brominated grafting agent (Mn was 27350, Mw/Mn was 1.57).

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

Example 2

(1) Preparation of polymer brominated grafting agent:

a. Preparation of macromolecular brominating agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced twice, and 1200g of cyclohexane, 1000g of vinyl bromide, and 1.4g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the temperature of the reactor reached 43°C, 0.8g of DCP was added and reacted for 2.4hr; then 55g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 34min until no free monomer was present. After the reaction was completed, the macromolecular brominating agent was obtained by washing and drying.

b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced twice, and 3200g cyclohexane, 1000g isoprene, and 1.3g THF were added to the polymerization kettle in sequence, the temperature was raised to 42°C, and 14.3mmol n-butyl lithium was added to start the reaction for 53min; then 220g 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- 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 colloid was wet-coagulated and dried to obtain a high molecular weight brominated grafting agent (Mn was 29120, Mw/Mn was 1.74).

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

Example 3

(1) Preparation of polymer brominated grafting agent:

a. Preparation of macromolecular brominating agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced three times, and 1400g of cyclohexane, 1000g of vinyl bromide, and 1.8g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the temperature of the reactor reached 48°C, 1.0g of DCP was added and reacted for 2.7 hours; then 60g 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 present. After the reaction was completed, the macromolecular brominating agent was obtained by washing and drying.

b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced three times, and 3400g cyclohexane, 1000g isoprene, and 1.6g THF were added to the polymerization kettle in sequence, the temperature was raised to 44°C, and 15.2mmol n-butyl lithium was added to start the reaction for 56min; then 230g 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- 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 colloid was wet condensed and dried to obtain a high molecular weight brominated grafting agent (Mn was 32540, Mw/Mn was 1.91).

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

Example 4

(1) Preparation of polymer brominated grafting agent:

a. Preparation of macromolecular brominating agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced three times, and 1600g of cyclohexane, 1000g of vinyl bromide, and 2.0g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the temperature of the reactor reached 50°C, 1.3g of DCP was added and reacted for 3.0 hours; then 70g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 40min until no free monomer was present. After the reaction was completed, the macromolecular brominating agent was obtained by washing and drying.

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

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

Example 5

(1) Preparation of polymer brominated grafting agent:

a. Preparation of macromolecular brominating agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced three times, and 1800g of cyclohexane, 1000g of vinyl bromide, and 2.3g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the temperature of the reactor reached 52°C, 1.6g of DCP was added and reacted for 3.5 hours; then 80g 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 present. After the reaction was completed, the macromolecular brominating agent was obtained by washing and drying.

b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced three times, and 3700g cyclohexane, 1000g isoprene, and 2.2g THF were added to the polymerization kettle in sequence, the temperature was raised to 47°C, and 17.7mmol n-butyl lithium was added to start the reaction for 62min; then 260g 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- 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 colloid was wet-coagulated and dried to obtain a high molecular weight brominated grafting agent (Mn was 40260, Mw/Mn was 2.35).

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

Example 6

(1) Preparation of polymer brominated grafting agent:

a. Preparation of macromolecular brominating agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced 4 times, and 2000g of cyclohexane, 1000g of vinyl bromide, and 3.0g of tert-dodecyl mercaptan were added to the reactor in sequence, stirred and mixed, and heated. When the temperature of the reactor reached 60°C, 2.0g of DCP was added and reacted for 4.0hr; then 100g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 50min until no free monomer was present. After the reaction was completed, the macromolecular brominating agent was obtained by washing and drying.

b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced 4 times, and 4000g cyclohexane, 1000g isoprene, and 3.0g THF were added to the polymerization kettle in sequence, the temperature was raised to 50°C, and 19.2mmol n-butyl lithium was added to start the reaction for 70min; then 300g 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- segments; finally, 600g of high molecular weight brominated 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 colloid was wet condensed and dried to obtain a high molecular weight brominated grafting agent (Mn was 44650, Mw/Mn was 2.64).

(2) Preparation of secondary brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was replaced 5 times, and 350g of methyl chloride, 150g of cyclohexane, and 15g of high molecular weight brominated grafting agent were added to the polymerization reactor, and stirred and dissolved for 35 minutes until they were completely dissolved; then when the temperature was lowered to -68°C, 1000g of methyl chloride, 475g of isobutylene, and 10g of isoprene were added in sequence, and stirred and mixed until the temperature of the polymerization system dropped to -100°C, and then 150g of methyl chloride, 4.52g of sesquiethylaluminum chloride and 0.098g of HCl were mixed and aged at -95°C for 30 minutes, and then added together to the polymerization system and stirred and reacted for 3.0 hours, and finally 50g of methanol was added, and the material was condensed, washed, and dried to obtain a brominated branched butyl rubber product. Sampling analysis: Standard samples were prepared, and the test properties are shown in Table 1.

Example 7

(1) Preparation of polymer brominated grafting agent:

a. Preparation of macromolecular brominating agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced 4 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 temperature of the reactor reached 55°C, 1.8g of DTBP was added and reacted for 3.7 hours; then 90g of isoprene was added to the polymerization reactor for end-capping, and the reaction was carried out for 45min until no free monomer was present. After the reaction was completed, the macromolecular brominating agent was obtained by washing and drying.

b. Preparation of high molecular weight brominated grafting agent: First, in a 15L stainless steel reactor with a jacket, argon gas was replaced 4 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 dodecyl lithium 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- 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 colloid was wet condensed and dried to obtain a high molecular weight brominated grafting agent (Mn was 42800, Mw/Mn was 2.51).

(2) Preparation of secondary brominated branched butyl rubber: First, in a 4L stainless steel reactor with a jacket, nitrogen was replaced 5 times, and 330g of ethylene dichloride, 130g of hexane, and 16g of high molecular weight brominated grafting agent were added to the polymerization reactor, and stirred and dissolved for 33 minutes until they were completely dissolved; then when the temperature dropped to -68°C, 1000g of ethylene dichloride, 473g of isobutylene, and 12g of isoprene were added in sequence, and stirred and mixed until the temperature of the polymerization system dropped to -100°C, and then 150g of ethylene dichloride, 4.45g of monoisobutyl aluminum chloride and 0.095g of HCl were mixed and aged at -95°C for 30 minutes, and then added together to the polymerization system and stirred and reacted for 2.6 hours, and finally 46g of ethanol was added, and the material was condensed, washed, and dried to obtain a brominated branched butyl rubber product. Sampling analysis: Standard samples were prepared, and the test properties are shown in Table 1.

Comparative Example 1

(1) Preparation of polymer brominated grafting agent:

a Preparation of macromolecular brominating agent: Other conditions are the same as those in Example 1, except that: monomer isoprene is not added for end-capping, that is: first, in a 15L stainless steel reactor with a jacket, argon gas is passed through and replaced twice, 1000 g of cyclohexane, 1000 g of vinyl bromide, and 1.0 g of tert-dodecyl mercaptan are added to the reactor in sequence, stirred and mixed, and heated. When the temperature of the reactor reaches 40°C, 0.5 g of DCP is added, and the reaction is carried out for 30 min until no free monomer is present. After the reaction is completed, the macromolecular brominating agent-1 is obtained by washing and drying.

b. Preparation of macromolecular brominated grafting agent: Other conditions were the same as those in Example 1, except that: no macromolecular brominating agent was added during the synthesis process, but macromolecular brominating agent-1 was added in an amount of 400 g, namely: first, in a 15L stainless steel reactor with a jacket, argon was passed through and replaced twice, 3000 g of cyclohexane, 1000 g of isoprene, and 1.0 g of THF were added to the polymerization reactor in sequence, the temperature was raised to 40° C., and 12.1 mmol of n-butyl lithium was added to start the reaction for 50 min; then 200 g of styrene was added to the polymerization reactor, 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 macromolecular brominating agent-1 was added to the polymerization reactor, the temperature was raised to 80° C., and the reaction was carried out for 50 min until no free monomer was present, and the glue was wet-coagulated and dried to obtain macromolecular brominated grafting agent-1 (Mn was 26120, Mw/Mn was 1.43).

(2) Preparation of secondary brominated branched butyl rubber: The other conditions were the same as those in Example 1, except that in the preparation of the 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 the reactor for 3 times, and 700 g of methyl chloride, 300 g of cyclohexane, and high molecular weight brominated grafting agent-1 were added to the reactor. 30g, stirred and dissolved for 30min until completely dissolved; then when the temperature dropped to -60℃, 500g of chloromethane, 450g of isobutylene, and 20g of isoprene were added in sequence, and stirred and mixed until the polymerization system temperature dropped to -90℃, then 100g of chloromethane, 1.55g of sesquiethylaluminum chloride and 0.016g of HCl were mixed and aged for 20min at -85℃, and then added together to the polymerization system and stirred and reacted for 1.0hr, and finally 25g of methanol was added, the material was condensed, washed, and dried to obtain a brominated branched butyl rubber product. Sampling analysis: Standard samples were made, and the test properties are shown in Table 1.

Comparative Example 2

(1) Preparation of polymer brominated grafting agent:

a. Preparation of macromolecular brominating agent: same as Example 2.

b. Preparation of 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, but low molecular weight vinyl bromide was directly added in an amount of 430 g, namely: first, in a 15L stainless steel reactor with a jacket, argon was passed through and replaced twice, 3200 g of cyclohexane, 1000 g of isoprene, and 1.3 g of THF were added to the polymerization reactor in sequence, the temperature was raised to 42° C., and 14.3 mmol of n-butyl lithium was added to start the reaction for 53 min; then 220 g of styrene was added to the polymerization reactor, 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 reactor, the temperature was raised to 80° C., and the reaction was carried out for 55 min until no free monomers were present, and the glue was wet-coagulated and dried to obtain high molecular weight brominated grafting agent-2 (Mn was 26720, Mw/Mn was 1.51).

(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 the 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 4L stainless steel reactor with a jacket, nitrogen was purged three times, 500 g of methyl chloride, 500 g of cyclohexane, and 28 g of the high molecular weight brominated grafting agent-2 were added to the polymerization reactor, and the mixture was stirred and dissolved for 35 min until it was completely dissolved; then, when the temperature was lowered to -64°C, 550 g of methyl chloride, 455 g of isobutylene, and 17 g of isoprene were added in sequence, and the mixture was stirred and mixed until the temperature of the polymerization system dropped to -91°C, and then 110 g of methyl chloride, 1.71 g of sesquiethylaluminum chloride and HCl were added. 0.056g was mixed and aged for 22min at -87℃, then added to the polymerization system and stirred for 1.6hr, and finally 30g of methanol was added, the material was condensed, washed and dried to obtain brominated branched butyl rubber product. Sampling analysis: Standard samples were prepared, and the test properties are shown in Table 1.

Comparative Example 3

(1) Preparation of polymer brominated grafting agent:

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

b. Preparation of high molecular weight brominated grafting agent: Other conditions were the same as those in Example 3, except that monomer styrene was not added during the preparation of the high molecular weight brominated grafting agent, namely: first, in a 15L stainless steel reactor with a jacket, argon was passed through and replaced three times, 3400g of cyclohexane, 1000g of isoprene, and 1.6g of THF were added to the polymerization reactor in sequence, the temperature was raised to 44°C, 15.2mmol of n-butyl lithium was added to start the reaction for 56min to form -IR- segments; finally, 450g of high molecular weight brominating agent was added to the polymerization reactor, the temperature was raised to 82°C, the reaction was carried out for 60min, until no free monomer was present, the gel was wet condensed and dried to obtain high molecular weight brominated grafting agent-3 (Mn was 28620, Mw/Mn was 1.42).

(2) Preparation of secondary brominated branched butyl rubber: Other conditions were the same as those in Example 3, except that: in the preparation process of the secondary brominated branched butyl rubber, instead of adding a high molecular weight brominated grafting agent, a high molecular weight brominated grafting agent-3 was added in an amount of 25 g, namely: first, in a 4L stainless steel reactor with a jacket, nitrogen was purged 4 times, 300 g of methyl chloride, 500 g of cyclohexane, and 25 g of the high molecular weight brominated grafting agent-3 were added to the polymerization reactor, and stirred and dissolved for 35 minutes until they were completely dissolved; then, when the temperature was lowered to -68°C, 600 g of methyl chloride, 459 g of isobutylene, and 16 g of isoprene were added in sequence, and the mixture was stirred and mixed until the temperature of the polymerization system dropped to -92°C, and then 120 g of methyl chloride, 2.73 g of sesquiethylaluminum chloride and HCl were added. 0.065g was mixed and aged for 24min at -88℃, then added to the polymerization system and stirred for 1.9hr, and finally 35g of methanol was added, the material was condensed, washed and dried to obtain brominated branched butyl rubber product. Sampling analysis: Standard samples were prepared, and the test properties are shown in Table 1.

Comparative Example 4

(1) Preparation of secondary brominated branched butyl rubber: Other conditions were the same as those in Example 4, except that: in the preparation of the 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 methyl chloride, 470 g of cyclohexane, and 22 g of vinyl bromide were added to the polymerization reactor, and stirred and dissolved for 35 min until they were completely dissolved; then, when the temperature was lowered to -68°C, 700 g of methyl chloride, 464 g of isobutylene, and 14 g of isoprene were added in sequence, and the mixture was stirred and mixed until the temperature of the polymerization system dropped to -94°C, and then 130 g of methyl chloride, 3.56 g of sesquiethylaluminum chloride, and HCl were added. 0.075g was mixed and aged for 26min at -90℃, then added to the polymerization system and stirred for 2.0hr, and finally 40g of methanol was added, the material was condensed, washed and dried to obtain brominated branched butyl rubber product. Sampling analysis: Standard samples were prepared, and the test properties are shown in Table 1.

Comparative Example 5

(1) Preparation of polymer brominated grafting agent:

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

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

(2) Preparation of secondary brominated branched butyl rubber: The other conditions were the same as those in Example 5, except that: in the preparation process of the secondary brominated branched butyl rubber, no high molecular weight brominated grafting agent was added, but a macromolecular brominating agent was added in an amount of 18 g, namely: first, in a 4L stainless steel reactor with a jacket, nitrogen was purged 4 times, 300 g of methyl chloride, 200 g of cyclohexane, and 18 g of the macromolecular brominating agent were added to the polymerization reactor, and stirred and dissolved for 35 minutes until they were completely dissolved; then, when the temperature was lowered to -68°C, 800 g of methyl chloride, 469 g of isobutylene, and 13 g of isoprene were added in sequence, and the mixture was stirred and mixed until the temperature of the polymerization system dropped to -96°C, and then 135 g of methyl chloride, 3.91 g of sesquiethylaluminum chloride and HCl were added. 0.086g was mixed and aged for 27min at -91℃, then added to the polymerization system and stirred for 2.3hr, and finally 43g of methanol was added, the material was condensed, washed and dried to obtain brominated branched butyl rubber product. Sampling analysis: Standard samples were prepared, and the test properties are shown in Table 1.

Comparative Example 6

(1) Preparation of polymer brominated grafting agent:

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

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

(2) Preparation of secondary brominated branched butyl rubber: Other conditions were the same as those in Example 6, except that: the amount of the high molecular weight brominated grafting agent added during the preparation of the secondary brominated branched butyl rubber was 5.0 g, namely: first, in a 4 L stainless steel reactor with a jacket, nitrogen was purged 5 times, 350 g of methyl chloride, 150 g of cyclohexane, and 5.0 g of the high molecular weight brominated grafting agent were added to the polymerization reactor, and stirred and dissolved for 35 min until they were completely dissolved; then, when the temperature was lowered to -68°C, 1000 g of methyl chloride, 475 g of isobutylene, and 10 g of isoprene were added in sequence, and the mixture was stirred and mixed until the temperature of the polymerization system dropped to -100°C, and then 150 g of methyl chloride, 4.52 g of sesquiethylaluminum chloride and HCl were added. 0.098g was mixed and aged for 30min at -95℃, then added to the polymerization system and stirred for 3.0hr, and finally 50g of methanol was added, the material was condensed, washed and dried to obtain brominated branched butyl rubber product. Sampling analysis: Standard samples were prepared, and the test properties are shown in Table 1.

Table 1 Properties of secondary brominated branched butyl rubber

Note: _t10 is the scorch time, which reflects the size of the scorch safety window; _t90 is the positive vulcanization time, which reflects the speed of vulcanization.

It can be seen from Table 1 that 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, showing good processing and vulcanization characteristics, while maintaining a high tensile strength and good air tightness.

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 protection scope of the claims and the content of the invention and is not limited by the implementation scheme. Simple replacement or modification of the present invention is still within the protection scope of the present invention.

Claims (12)

1. a preparation method of secondary position brominated branched butyl rubber, the preparation method may further comprise the steps: S1: Add the polymer brominated grafting agent into the mixed solvent, and stir until the polymer brominated grafting agent is completely dissolved to obtain a mixed solution; S2: cooling down, adding diluent, isobutylene and isoprene to the mixed solution in step S1 in sequence, fully stirring and mixing to obtain a polymerization reaction system, and cooling down again; S3: Mix and age the diluent and the co-initiator, then add it to the polymerization reaction system of step S2 and stir the reaction fully, then add the terminator, discharge the material, coagulate, wash, and dry to obtain the secondary brominated branched butyl rubber ; 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 as shown in formula I:

Among them, 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 polymer The number-average molecular weight (Mn) of the brominated grafting agent is 27000-45000, and the ratio (Mw/Mn) of the weight-average molecular weight to the number-average molecular weight is 1.57-2.64. 2. The preparation method of secondary brominated branched butyl rubber according to claim 1, characterized in that, in step S1, the mass ratio of the mixed solvent to the polymer brominated grafting agent is 100 to 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 preparation method of secondary brominated branched butyl rubber according to claim 1, characterized in that, in step S2, the cooling to a temperature of -60°C to -80°C; the cooling to a temperature of It is -100～-90°C. 4. The preparation method of secondary brominated branched butyl rubber according to claim 1, characterized in that, in step S2, the mass ratio of the diluent, isobutylene and isoprene is 100 to 200:90 ~95: 2~4. 5. The preparation method of secondary brominated branched butyl rubber according to claim 1, characterized in that, in step S3, the mass ratio of the diluent, co-initiator and terminator is 20-30:0.01 ~1.0: 5~10. 6. the preparation method of secondary position brominated branched butyl rubber according to claim 1, is characterized in that, the preparation method of described polymer brominated grafting agent specifically comprises the following steps: a preparation of macromolecule brominating agent: taking the mass of vinyl bromide as 100 parts, first add 100 to 200 parts of solvent, 100 parts of vinyl bromide, and 0.1 to 0.3 parts of molecular weight regulator in the reactor after inert gas replacement, Stir, mix and heat, when the temperature of the reactor reaches 40-60°C, add 0.05-0.2 parts of the first initiator, react for 2.0-4.0 hours, and the conversion rate of vinyl bromide monomer reaches 100%; then add isoamyl into the reactor 5 to 10 parts of diene are capped, reacted for 30 to 50 minutes, until no free monomer exists, after the reaction is completed, the macromolecular brominating agent is obtained by washing and drying; b Preparation of polymer brominated grafting agent: based on 100% of the total mass of the reaction monomer, first add 300wt% to 400wt% solvent, 100wt% isoprene, and 0.1wt% to the reactor after inert gas replacement ~0.3wt% structure modifier, after heating up to 40~50°C, add the second initiator to react for 50~70min; ~60min to form -IR-PS- segment; finally add 40wt%~60wt% macromolecular bromination agent to the reaction kettle, heat up to 80~85°C, react for 50~80min, until no free monomer exists After the reaction is completed, the polymer brominated grafting agent is obtained by wet coagulation and drying. 7. the preparation method of secondary position brominated branched butyl rubber according to claim 6, is characterized in that, described molecular weight regulator is tertiary decanyl mercaptan, tertiary dodecyl mercaptan, tertiary tetradecyl mercaptan At least one of alcohol, tertiary hexadecanyl mercaptan, preferably tertiary dodecyl mercaptan; The first initiator is an organic peroxide, selected from di-tert-butyl hydroperoxide, 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane, di-tert-butyl peroxide 1. At least one of dicumyl peroxide, preferably dicumyl peroxide; The structure modifier is a polar organic compound, selected from the group consisting of diethylene glycol dimethyl ether, tetrahydrofuran, ether, ethyl methyl ether, anisole, diphenyl ether, ethylene glycol dimethyl ether , at least one of triethylamine, preferably tetrahydrofuran. 8. the preparation method of second-position brominated branched butyl rubber according to claim 6, is characterized in that, described second initiator is hydrocarbyl monolithium compound RLi, is selected from n-butyllithium, sec-butyllithium , methyl butyl lithium, phenyl butyl lithium, naphthalene lithium, cyclohexyl lithium, dodecyl lithium, preferably n-butyl lithium. 9. according to the preparation method of claim 2 or 6 described secondary position brominated branched butyl rubbers, it is characterized in that, described solvent is pentane, hexane, octane, heptane, hexanaphthene, benzene, At least one of toluene, xylene and ethylbenzene, preferably cyclohexane. 10. the preparation method of secondary position brominated branched butyl rubber according to claim 1, is characterized in that, described diluent is halogenated alkane, is selected from monochloromethane, methylene dichloride, carbon tetrachloride, dichloromethane At least one of ethyl chloride, tetrachloropropane, heptachloropropane, monofluoromethane, difluoromethane, tetrafluoroethane, carbon hexafluoride, and fluorobutane, preferably monochloromethane. 11. the preparation method of secondary position brominated branched butyl rubber according to claim 1, is characterized in that, described co-initiator is compounded in proportion by alkyl aluminum halide and protonic acid; Aluminum is selected from diethylaluminum monochloride, diisobutylaluminum monochloride, methylaluminum dichloride, sesquiethylaluminum chloride, sesquiisobutylaluminum chloride, n-propylaluminum dichloride, dichloroaluminum At least one of isopropyl aluminum, dimethyl aluminum chloride and ethyl aluminum chloride, preferably sesquiethyl aluminum chloride; the protic acid is selected from HCI, HF, HBr, H ₂ SO ₄ , H One of ₂ CO ₃ , H ₃ PO ₄ and HNO ₃ , preferably HCI; the molar ratio of the protonic acid to the alkylaluminum halide is 0.01:1˜0.1:1. 12. The preparation method of secondary brominated branched butyl rubber according to claim 1, characterized in that, the terminator is at least one of methanol, ethanol and butanol.