A preparation method for improving the monomer concentration of butyl rubber polymerization and the solid content of butyl rubber

Abstract

The application discloses a preparation method for improving butyl rubber polymer monomer concentration and butyl rubber solid content, and belongs to the technical field of butyl rubber synthesis. The preparation method for improving butyl rubber polymer monomer concentration and butyl rubber solid content. The preparation method has the common effect of stabilizers and initiators (main initiators and auxiliary initiators), and fundamentally solves the problems of concentrated reaction heat release, excessive temperature rise and polymerization out of control which are prone to occur when the butyl rubber solid content in a reaction solution is improved by simply increasing the polymer monomer concentration in the traditional process. Under the same process conditions and equipment load, the monomer addition amount can be safely increased, the butyl rubber glue liquid solid content is significantly improved, the effective output of the device is improved, the energy consumption and solvent consumption per unit product are reduced, and finally the comprehensive optimization effect of more stable reaction, higher solid content and lower production cost is achieved. Moreover, the preparation method further improves the product quality stability of butyl rubber.

Description

Technical Field

[0001] This invention relates to the field of butyl rubber synthesis technology, and more particularly to a method for preparing butyl rubber by increasing the concentration of polymeric monomers and the solid content of butyl rubber. Background Technology

[0002] Butyl rubber is a linear polymer composed of isobutylene (IB) and a small amount of isoprene (IP) monomers bonded together end-to-end. It is produced through a cationic reaction at a low temperature of -90℃ to -100℃. Its initiation system consists of an initiator and a co-initiator forming an ion pair with initiating activity. The tightness of the ion pair determines the activity of the initiator and the initiation rate of the polymerization reaction. Cationic donors are generally used as initiators, typically including carbocation donors and proton donors; Lewis acids are used as co-initiators, commonly boron trifluoride, titanium tetrachloride, aluminum trichloride, and dichloroethylaluminum. Based on the state of the polymer during polymerization, it can be divided into solution polymerization and slurry polymerization, mainly depending on the polymer's solubility in the diluent. Industrially, hexane is generally used as the diluent for solution polymerization, while chloromethane is used for slurry polymerization. Slurry polymerization has a high monomer concentration, low system viscosity, is easy to cool, and is less prone to glue buildup and pipe blockage, making it the most widely used polymerization method in industry.

[0003] Commercial butyl rubber contains only 0.6% to 2.5% isoprene in its main chain. Due to its low degree of unsaturation and the large number of side methyl groups in its molecular chain, butyl rubber has good chemical and thermal stability, and its air tightness is particularly outstanding. To this day, butyl rubber remains one of the irreplaceable materials for manufacturing tire inner tubes and vulcanized bladders.

[0004] In the production of butyl rubber, under the same process operating conditions, equipment load, energy consumption, and material consumption, a higher solid content of butyl rubber in the dilution system means a greater amount of effective rubber product that can be produced per unit time. By increasing the solid content in the diluent, effective output can be increased without significantly increasing production input, while reducing energy consumption and solvent consumption per unit product, thereby achieving improved production efficiency and reduced production costs.

[0005] Currently, increasing the concentration or solid content of butyl rubber monomers will cause a series of chain reactions, as follows:

[0006] The rate of heat generation in the reaction increases dramatically: the cationic polymerization of isobutylene-isoprene in butyl rubber is a rapid and strongly exothermic reaction. With the increase of solid content, there are more reactive monomers per unit volume. The heat release of the polymerization reaction increases exponentially in a short time, far exceeding the conventional heat removal capacity of the polymerization reactor, and the temperature rise of the system gets out of control.

[0007] A sudden increase in system viscosity leads to glue adhesion and agglomeration: The increase in solid content reduces the dispersibility of the polymer in the diluent, and the system viscosity increases significantly. Polymer particles are prone to sticking together and forming agglomerates. At the same time, they are very easy to be adsorbed on the inner wall of the polymerization reactor and the inner wall of the pipes, forming glue adhesion. This not only further hinders the heat exchange efficiency of the reactor, but also causes pipe blockage and increased stirring resistance inside the reactor.

[0008] A vicious cycle of process stability: the agglomeration of the adhesive residue becomes a new polymerization reaction site, exacerbating local overheating and further increasing the heat generation rate; while insufficient heat removal capacity leads to a sustained high system temperature, accelerating polymer adhesion to the walls, ultimately requiring frequent shutdowns of the polymerization reactor to clean the adhesive residue, significantly shortening the operating cycle.

[0009] Therefore, it is crucial to research and develop a novel method for preparing butyl rubber in order to increase the concentration of butyl rubber monomers and the solid content in the reaction system. Summary of the Invention

[0010] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing butyl rubber with increased monomer concentration and butyl rubber solid content. The preparation method significantly increases the butyl rubber solid content in the reaction system during polymerization, resulting in a significant reduction in temperature rise and a significant increase in monomer conversion rate.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] This invention provides a method for preparing butyl rubber with increased monomer concentration and solid content, comprising the following steps:

[0013] (1) Mix isobutylene, isoprene and diluent to obtain a monomer solution;

[0014] (2) Mix the solution containing the main initiator and the solution containing the co-initiator to obtain an initiator solution, and age it to obtain an aged initiator solution;

[0015] There is no specific order between (1) and (2); (3) the polymer monomer solution and the aged initiator solution are mixed to react and obtain reaction solution S;

[0016] (4) Add an alcohol terminator to the reaction solution S to precipitate butyl rubber;

[0017] At least one of the monomer solution or the initiator solution contains a stabilizer; when both are present, the stabilizers may be the same or different.

[0018] The stabilizer is selected from one or more of acid, alcohol, ketone, and ester stabilizers;

[0019] The main initiator is selected from Lewis acid initiators;

[0020] The co-initiator is selected from initiators that provide carbocations or protons.

[0021] Preferably, in the above preparation method, step (1) is performed first, followed by step (2).

[0022] The preparation method described in this invention introduces a specific stabilizer, which works together with other raw materials (especially initiators) to significantly increase the solid content of butyl rubber in the reaction solution and achieve long-term stable operation of the preparation device while ensuring a stable and controllable reaction.

[0023] The stabilizer has a dual synergistic effect: on the one hand, the stabilizer can complex with the Lewis acid, the main initiator in the reaction system, and reduce the acidity and initiation activity of the Lewis acid through electronic effects, thereby gently reducing the polymerization initiation rate and avoiding excessively violent reactions during the initiation stage; on the other hand, the stabilizer can interact with the active centers formed during chain growth, moderately passivating the active centers, weakening the chain growth reaction rate, and making the polymerization process smoother.

[0024] Under the combined effect of the dual regulation mechanism, the polymerization rate of butyl rubber is significantly slowed down, the rate of exothermic reaction is more uniform, the temperature rise of the system is significantly reduced, and the temperature fluctuation is effectively suppressed.

[0025] The preparation method described in this invention achieves synergistic regulation of polymerization kinetics, system viscosity, and heat exchange environment through the combined action of stabilizers and initiators (main initiator and co-initiator). While increasing the concentration of polymeric monomers in the diluent and the solid content of butyl rubber in the reaction solution, it effectively avoids problems such as excessively rapid exothermic reaction rates and localized overheating of the system. It fundamentally suppresses phenomena such as glue buildup on the inner wall of the polymerization reactor, decreased heat exchange efficiency, and deteriorated operational stability. This truly achieves stable polymerization operation with high solid content, low exothermic reaction, and long cycle time, significantly improving the production efficiency of the butyl rubber plant without increasing production energy consumption or reactor cleaning frequency. Simultaneously, the increased solid content of butyl rubber in the reaction solution reduces the recovery cost of the diluent, improving the economic benefits of butyl rubber production.

[0026] Preferably, the stabilizer is selected from aromatic acids, alcohols, ketones or esters.

[0027] More preferably, the stabilizer is selected from any of the following structures:

[0028] ;

[0029] R, R1, and R2 are independently selected from H or C1-C30 straight-chain or branched alkyl groups.

[0030] The C1-C30 straight-chain or branched alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl (isopentyl), 1-ethylpropyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl (neopentyl), n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl (isohexyl), 1-ethylbutyl, 2-Ethylbutyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 1,4-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl to n-triacontyl, etc.

[0031] In a further preferred embodiment of the present invention, the stabilizer is selected from one or more of dioctyl isophthalate, dibutyl phthalate, diethyl terephthalate, dimethyl terephthalate, or dipropanol.

[0032] Preferably, when added to the monomer solution, the amount of stabilizer added is 100-3000 ppm (where ppm represents parts per million) of the monomer solution; more preferably, it is 300-2000 ppm; in some specific embodiments of the present invention, it is preferably 400 ppm, 600 ppm or 700 ppm.

[0033] When added to the initiator solution, the molar ratio of the stabilizer to the co-initiator is (0.02-0.5):1; more preferably (0.04-0.3):1; and in some specific embodiments of the present invention, it is preferably 0.06:1, 0.1:1 or 0.2:1.

[0034] Preferably, the diluent of the present invention is selected from polar halogenated alkanes and / or nonpolar alkanes;

[0035] Preferably, the halogen in the polar halogenated alkane is selected from fluorine, chlorine or bromine, and the alkane is selected from C1-C20 straight-chain or branched-chain alkanes;

[0036] Preferably, the nonpolar alkane is selected from C1-C20 straight-chain or branched-chain alkanes, or C3-C10 cycloalkanes.

[0037] The C1-C20 straight-chain or branched alkanes include, but are not limited to, methane, ethane, n-propane, isopropane, n-butane, isobutane, tert-butane, n-pentane, 1-methylbutane, 2-methylbutane, 3-methylbutane (isopentane), 1-ethylpropane, 1,2-dimethylpropane, 1,1-dimethylpropane (neopentane), n-hexane, 1-methylpentane, 2-methylpentane, 3-methylpentane, 4-methylpentane (isohexane), and 1-ethylbutane. 2-Ethylbutane, 1,1-Dimethylbutane, 1,2-Dimethylbutane, 1,3-Dimethylbutane, 1,4-Dimethylbutane, 2,2-Dimethylbutane, 2,3-Dimethylbutane, 3,3-Dimethylbutane, 1-Ethyl-1-methylpropane, 1-Ethyl-2-methylpropane, 1,1,2-Trimethylpropane, 1,2,2-Trimethylpropane, n-Heptane, n-Octane, n-Nonane, n-Decanane, n-Undecane to n-Eicosane, etc.

[0038] The C3-C10 cycloalkanes include, but are not limited to, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, and cyclodecane.

[0039] More preferably, the diluent is selected from one or more of n-hexane, cyclohexane, isopentane, n-pentane, chloromethane, dichloromethane, fluoromethane, 1,1-difluoromethane, 1,1,1-trifluoromethane, 1,1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane, or 1,1,1,2,2-pentafluoroethane. More preferably, it is chloromethane.

[0040] Preferably, the total concentration of isobutylene and isoprene in the monomer solution is 10wt%-30wt%; more preferably, it is 12wt%-20wt%.

[0041] Preferably, the Lewis acid initiator is selected from one or more of dichloroethylaluminum, aluminum trichloride, boron trifluoride, and titanium tetrachloride; more preferably, it is dichloroethylaluminum or aluminum trichloride.

[0042] The initiator that provides carbocations or protons is selected from hydrogen chloride, hydrogen bromide, or tert-butyl chloride; more preferably, it is hydrogen chloride.

[0043] Preferably, the solvents in the solution containing the main initiator and the solution containing the co-initiator are independently selected from one or more of n-hexane, chloromethane, and dichloromethane; more preferably, the solvents in both the solution containing the main initiator and the solution containing the co-initiator are n-hexane.

[0044] Preferably, the molar ratio of isobutylene to isoprene is (2:98)-(12:88).

[0045] Preferably, the ratio of the total molar number of the polymeric monomers isobutylene and isoprene to the molar number of the main initiator is (500-5000):1; more preferably (600-2000):1; in some specific embodiments of the present invention, it is preferably 1100:1, 700:1, or 800:1.

[0046] Preferably, the molar ratio of the main initiator to the co-initiator is (5-10):1; more preferably (6-9):1; and in some specific embodiments of the present invention, it is preferably 8:1.

[0047] Preferably, the reaction temperature in step (3) of this invention is -70°C to -100°C; more preferably, it is -75°C to -95°C.

[0048] The reaction time is preferably 5-30 min.

[0049] In the above preparation method, the aging temperature in step (2) is preferably -70°C to -100°C; more preferably -90°C to -100°C.

[0050] The aging time is preferably 5-30 minutes.

[0051] The product precipitated in step (4) above also includes post-treatment such as drying.

[0052] The present invention does not impose any particular limitation on the drying method, and any drying method known to those skilled in the art is acceptable.

[0053] In some specific embodiments of the present invention, the drying is preferably vacuum drying.

[0054] The vacuum drying temperature is preferably 40℃-50℃; more preferably 45℃.

[0055] Compared with the prior art, the preparation method for increasing the concentration of butyl rubber polymer monomers and the solid content of butyl rubber provided by the present invention includes the following steps: (1) mixing isobutylene, isoprene and diluent to obtain a polymer monomer solution; (2) mixing a solution containing a main initiator and a solution containing a co-initiator to obtain an initiator solution, and aging to obtain an aged initiator solution; there is no specific order between (1) and (2);

[0056] (3) The monomer solution and the aged initiator solution are mixed to react and obtain reaction solution S; (4) An alcohol terminator is added to reaction solution S to precipitate butyl rubber; at least one of the monomer solution or the initiator solution contains a stabilizer; the stabilizer is selected from one or more of acid, alcohol, ketone, and ester stabilizers; the main initiator is selected from Lewis acid initiators; the co-initiator is selected from initiators that provide carbocations or protons. The preparation method of the present invention fundamentally solves the problems of concentrated exothermic reaction, excessive temperature rise, and uncontrolled polymerization that are easily encountered when simply increasing the monomer concentration to increase the solid content of butyl rubber in the reaction solution in the traditional process. Under the same process conditions and equipment load, the monomer addition can be safely increased, significantly increasing the solid content of butyl rubber solution, thereby increasing the effective output of the device, reducing the energy consumption and solvent consumption per unit product, and ultimately achieving a comprehensive optimization effect of more stable reaction, higher solid content, and lower production cost. Furthermore, the preparation method further improves the product quality stability of butyl rubber. Attached Figure Description

[0057] Figure 1 The graphs show the magnitude and rate of temperature rise in the polymerization reactions of Examples 1-3 and the comparative examples.

[0058] Figure 2 The reaction mechanism diagrams for Examples 1-7 of this invention are shown. Detailed Implementation

[0059] To further illustrate the present invention, the following detailed description of the preparation method for increasing the concentration of butyl rubber polymer monomers and the solid content of butyl rubber provided by the present invention is provided in conjunction with embodiments.

[0060] Example 1

[0061] 138g of chloromethane was placed in a reactor in a -95℃ cold bath;

[0062] Then add 22.425g of isobutylene and 0.69g of isoprene to obtain a monomer solution;

[0063] Add 0.012 g of dioctyl isophthalate to the monomer solution and start stirring;

[0064] Take 0.22g of 20wt% dichloroethylaluminum in n-hexane and 5g of 0.025wt% HCl in n-hexane and mix them to obtain an initiator solution, and age it in a cold bath at -95℃ for 10min.

[0065] The initiator solution was slowly added dropwise to the monomer solution, and the reaction was allowed to proceed for 10 minutes. The temperature was then raised to -80°C, and the solid content of butyl rubber in the reaction solution was 12.9 wt%.

[0066] Add 50g of ethanol to the reaction vessel to terminate the reaction and precipitate the product;

[0067] Place the product in a vacuum drying oven and dry at 45°C.

[0068] 20.8 g of butyl rubber was obtained, with a conversion rate of 90%. Mn = 92358 g / mol, Mw = 437526 g / mol, and Mw / Mn = 4.74.

[0069] Example 2

[0070] 138g of chloromethane was placed in a reactor in a -95℃ cold bath;

[0071] Add 24.375g of isobutylene and 0.75g of isoprene to obtain a monomer solution, and start stirring.

[0072] Take 0.44g of 20wt% dichloroethylaluminum in n-hexane and 10g of 0.025wt% HCl in n-hexane and mix them together to obtain an initiator solution, and age it in a cold bath at -95℃ for 10min.

[0073] Add 0.012 g of dioctyl isophthalate to the initiator solution;

[0074] The initiator solution was slowly added dropwise to the monomer solution, and the reaction was allowed to proceed for 10 minutes. The temperature was then raised to -85°C, and the solid content of butyl rubber in the reaction solution was 14.2 wt%.

[0075] Add 50g of ethanol to the reaction vessel to terminate the reaction and precipitate the product;

[0076] Place the product in a vacuum drying oven and dry at 45°C.

[0077] 23.1 g of butyl rubber was obtained, with a conversion rate of 92%, Mn = 113762 g / mol, Mw = 472925 g / mol, and Mw / Mn = 4.15.

[0078] Example 3

[0079] 138g of chloromethane was placed in a reactor in a -95℃ cold bath;

[0080] Then add 29.25g of isobutylene and 0.9g of isoprene to obtain a monomer solution;

[0081] Add 0.012 g of dioctyl isophthalate to the monomer solution and start stirring;

[0082] Take 0.44g of 20wt% dichloroethylaluminum in n-hexane and 10g of 0.025wt% HCl in n-hexane and mix them to obtain an initiator solution, and age it in a cold bath at -95℃ for 10min.

[0083] Add 0.012 g of dioctyl isophthalate to the initiator solution;

[0084] The initiator solution was slowly added dropwise to the monomer solution, and the reaction was allowed to proceed for 10 minutes. The temperature was then raised to -88°C, and the solid content of butyl rubber in the reaction solution was 17 wt%.

[0085] Add 50g of ethanol to the reaction vessel to terminate the reaction and precipitate the product;

[0086] Place the product in a vacuum drying oven and dry at 45°C.

[0087] 28.6 g of butyl rubber was obtained, with a conversion rate of 95%, Mn = 156382 g / mol, Mw = 526793 g / mol, and Mw / Mn = 3.37.

[0088] Example 4

[0089] 138g of chloromethane was placed in a reactor in a -95℃ cold bath;

[0090] Then add 28.275g of isobutylene and 0.87g of isoprene to obtain a monomer solution;

[0091] Add 0.0116 g of dibutyl phthalate to the monomer solution and start stirring;

[0092] Take 0.44g of 20wt% dichloroethylaluminum in n-hexane and 10g of 0.025wt% HCl in n-hexane and mix them to obtain an initiator solution, and age it in a cold bath at -95℃ for 10min.

[0093] Add 0.0116 g of dibutyl phthalate to the initiator solution;

[0094] The initiator solution was slowly added dropwise to the monomer solution, and the reaction was allowed to proceed for 10 minutes. The temperature was then raised to -89°C, and the solid content of butyl rubber in the reaction solution was 15.5 wt%.

[0095] Add 50g of ethanol to the reaction vessel to terminate the reaction and precipitate the product;

[0096] Place the product in a vacuum drying oven and dry at 45°C.

[0097] 25.93 g of butyl rubber was obtained, with a conversion rate of 89%. Mn = 142836 g / mol, Mw = 517693 g / mol, and Mw / Mn = 3.62.

[0098] Example 5

[0099] 138g of chloromethane was placed in a reactor in a -95℃ cold bath;

[0100] Then add 29.25g of isobutylene and 0.9g of isoprene to obtain a monomer solution;

[0101] Add 0.015 g of diethyl terephthalate to the monomer solution and start stirring;

[0102] Take 0.44g of 20wt% dichloroethylaluminum in n-hexane and 10g of 0.025wt% HCl in n-hexane and mix them to obtain an initiator solution, and age it in a cold bath at -95℃ for 10min.

[0103] Add 0.015 g of diethyl terephthalate to the initiator solution;

[0104] The initiator solution was slowly added dropwise to the monomer solution, and the reaction was allowed to proceed for 10 minutes. The temperature was then raised to -90°C, and the solid content of butyl rubber in the reaction solution was 14.5 wt%.

[0105] Add 50g of ethanol to the reaction vessel to terminate the reaction and precipitate the product;

[0106] Place the product in a vacuum drying oven and dry at 45°C.

[0107] 23.83 g of butyl rubber was obtained, with a conversion rate of 91%. Mn = 152638 g / mol, Mw = 536973 g / mol, and Mw / Mn = 3.51.

[0108] Example 6

[0109] 138g of chloromethane was placed in a reactor in a -95℃ cold bath;

[0110] Then add 30.225g of isobutylene and 0.93g of isoprene to obtain a monomer solution;

[0111] Add 0.0187 g of p-phenylenedimethyl ether to the monomer solution and start stirring;

[0112] Take 0.44g of 20wt% dichloroethylaluminum in n-hexane and 10g of 0.025wt% HCl in n-hexane and mix them to obtain an initiator solution, and age it in a cold bath at -95℃ for 10min.

[0113] Add 0.0187 g of p-phenylenedimethyl ether to the initiator solution;

[0114] The initiator solution was slowly added dropwise to the monomer solution, and the reaction was allowed to proceed for 10 minutes. The temperature was then raised to -89°C, and the solid content of butyl rubber in the reaction solution was 16.6 wt%.

[0115] Add 50g of ethanol to the reaction vessel to terminate the reaction and precipitate the product;

[0116] Place the product in a vacuum drying oven and dry at 45°C.

[0117] 28.04 g of butyl rubber was obtained, with a conversion rate of 90%. Mn = 157693 g / mol, Mw = 539864 g / mol, and Mw / Mn = 3.42.

[0118] Example 7

[0119] 138g of chloromethane was placed in a reactor in a -95℃ cold bath;

[0120] Then add 29.25g of isobutylene and 0.9g of isoprene to obtain a monomer solution;

[0121] Add 0.021 g of terephthalic acid to the monomer solution and start stirring;

[0122] Take 0.44g of 20wt% dichloroethylaluminum in n-hexane and 10g of 0.025wt% HCl in n-hexane and mix them to obtain an initiator solution, and age it in a cold bath at -95℃ for 10min.

[0123] Add 0.021g of terephthalic acid to the initiator solution;

[0124] The initiator solution was slowly added dropwise to the monomer solution, and the reaction was allowed to proceed for 10 minutes. The temperature was then raised to -90°C, and the solid content of butyl rubber in the reaction solution was 16.5 wt%.

[0125] Add 50g of ethanol to the reaction vessel to terminate the reaction and precipitate the product;

[0126] Place the product in a vacuum drying oven and dry at 45°C.

[0127] 27.74 g of butyl rubber was obtained, with a conversion rate of 92%. Mn = 142732 g / mol, Mw = 526739 g / mol, and Mw / Mn = 3.69.

[0128] Comparative Example

[0129] 138g of chloromethane was placed in a reactor in a -95℃ cold bath;

[0130] Add 29.25g isobutylene and 0.9g isoprene to obtain a monomer solution, and start stirring.

[0131] Take 0.44g of 20wt% dichloroethylaluminum in n-hexane and 10g of 0.025wt% HCl in n-hexane and mix them to obtain an initiator solution, and age it in a cold bath at -95℃ for 10min.

[0132] The initiator solution was slowly added dropwise to the monomer solution, and the reaction was allowed to proceed for 10 minutes. The temperature was then raised to -75°C, and the solid content of butyl rubber in the reaction solution was 11.65 wt%.

[0133] Add 50g of ethanol to the reaction vessel to terminate the reaction and precipitate the product;

[0134] Place the product in a vacuum drying oven and dry at 45°C.

[0135] 19.6 g of butyl rubber was obtained, with a conversion rate of 65%, Mn = 64856 g / mol, Mw = 356758 g / mol, and Mw / Mn = 5.5.

[0136] Figure 1 The graphs show the magnitude and rate of temperature rise in the polymerization reactions of Examples 1-3 and the Comparative Example, used to characterize the relationship between the magnitude and rate of temperature rise in the polymerization reaction under different stabilizer addition methods; the temperature rise rate (the rate at which the temperature increases) is ranked as follows: stabilizer added to the initiation system (i.e., the initiator solution) and the mixture (i.e., the monomer solution) (Example 3) < stabilizer added to the initiation system (Example 2) < stabilizer added to the mixture (Example 1) < no stabilizer added (Comparative Example).

[0137] By comparing Examples 1-7 (especially Example 3) and the comparative example, it can be seen that after adding the stabilizer, the solid content of butyl rubber in the reaction system during the polymerization of butyl rubber in Examples 1-7 was significantly increased, the reaction temperature rise was significantly reduced, and the monomer conversion rate was greatly improved. Simultaneously, the resulting polymer had a higher molecular weight and a narrower and more uniform molecular weight distribution. The reason for this may be the combined effect of the specific stabilizer and initiator solution, which reduced the acidity of the Lewis acid in the initiator solution and weakened the carbon chain growth activity, preventing the initiation reaction from being too vigorous and making the polymerization process more gradual (the specific mechanism is as follows). Figure 2 As shown, Figure 2 This was used to reveal the role of stabilizers in reducing the acidity of Lewis acids through complexation and in reducing the polymerization rate through binding with terminal active sites.

[0138] Experimental results show that stabilizers can effectively improve the stability of butyl rubber polymerization, significantly increase the monomer concentration and process solids content in the polymerization system, and improve polymerization efficiency and monomer conversion rate without adversely affecting the polymer molecular weight and its distribution. Therefore, introducing stabilizers into the butyl rubber polymerization system is a feasible and efficient technical means to effectively increase monomer concentration, improve process solids content, and enhance polymerization stability.

[0139] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing butyl rubber with increased monomer concentration and solid content, characterized in that, Includes the following steps: (1) Mix isobutylene, isoprene and diluent to obtain a monomer solution; (2) Mix the solution containing the main initiator and the solution containing the co-initiator to obtain an initiator solution, and age it to obtain an aged initiator solution; There is no specific order between (1) and (2); (3) The monomer solution and the aged initiator solution are mixed and reacted to obtain reaction solution S; (4) Add an alcohol terminator to the reaction solution S to precipitate butyl rubber; At least one of the monomer solution or the initiator solution contains a stabilizer; The stabilizer is selected from one or more of acid, alcohol, ketone, and ester stabilizers; The main initiator is selected from Lewis acid initiators; The co-initiator is selected from initiators that provide carbocations or protons.

2. The preparation method according to claim 1, characterized in that, The stabilizer is selected from aromatic acids, alcohols, ketones or ester stabilizers.

3. The preparation method according to claim 2, characterized in that, The stabilizer is selected from any of the following structures: ； R, R1, and R2 are independently selected from H or C1-C30 straight-chain or branched alkyl groups.

4. The preparation method according to claim 3, characterized in that, The stabilizer is selected from one or more of dioctyl isophthalate, dibutyl phthalate, diethyl terephthalate, dimethyl terephthalate, or dipropanol.

5. The preparation method according to any one of claims 1-4, characterized in that, When added to a monomer solution, the amount of stabilizer added is 100-3000 ppm of the monomer solution; When added to the initiator solution, the molar ratio of the stabilizer to the co-initiator is (0.02-0.5):

1.

6. The preparation method according to claim 1, characterized in that, The diluent is selected from polar halogenated alkanes and / or nonpolar alkanes; The halogen in the polar halogenated alkane is selected from fluorine, chlorine or bromine, and the alkane is selected from C1-C20 straight-chain or branched alkane. The nonpolar alkanes are selected from C1-C20 straight-chain or branched alkanes, or C3-C10 cycloalkanes.

7. The preparation method according to claim 6, characterized in that, The diluent is selected from one or more of the following: n-hexane, cyclohexane, isopentane, n-pentane, monochloromethane, dichloromethane, fluoromethane, 1,1-difluoromethane, 1,1,1-trifluoromethane, 1,1,1,2-tetrafluoroethane, 1,1,2,2-tetrafluoroethane, or 1,1,1,2,2-pentafluoroethane.

8. The preparation method according to claim 1, characterized in that, The total concentration of isobutylene and isoprene in the monomer solution is 10wt%-30wt%; The Lewis acid initiator is selected from one or more of dichloroethylaluminum, aluminum trichloride, boron trifluoride, and titanium tetrachloride; The initiator that provides carbocations or protons is selected from hydrogen chloride, hydrogen bromide, or tert-butyl chloride; The solvents in the solutions containing the primary initiator and the co-initiator are independently selected from one or more of n-hexane, chloromethane, and dichloromethane.

9. The preparation method according to claim 1, characterized in that, The molar ratio of isobutylene to isoprene is (2:98)-(12:88). The ratio of the total molar number of the polymeric monomers isobutylene and isoprene to the molar number of the main initiator is (500-5000):1; The molar ratio of the main initiator to the co-initiator is (5-10):

1.

10. The preparation method according to claim 1, characterized in that, The reaction temperature in step (3) is -70℃ to -100℃.

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