Flexible switching production method and equipment for low-cis-polybutadiene rubber, solution polymerized styrene-butadiene rubber and hydroxyl-terminated liquid polybutadiene rubber

Abstract

The invention provides a flexible switching production method and equipment for low cis-polybutadiene rubber (LCBR), solution polymerized styrene-butadiene rubber (SSBR) and hydroxyl-terminated liquid polybutadiene rubber (HTPB), the flexible switching production equipment comprises an initiator production device and a polymerization unit, and the flexible switching production method comprises the following steps: mixing cyclohexane and n-hexane according to a volume ratio of 6.5: 3.5-7: 3, adding an initiator, and stirring to obtain a mixture; forming a mixed solvent; the method comprises the following steps: adding a monomer, an active agent, an initiator and a mixed solvent into a polymerization kettle 31 of a polymerization unit, and carrying out polymerization reaction to obtain a low-cis-polybutadiene, solution polymerized styrene-butadiene or hydroxyl-terminated liquid polybutadiene rubber solution; a novel protection initiator tert-butyl dimethyl siloxy propyl sodium is designed, and hydroxyl-terminated liquid polybutadiene rubber with a controllable structure is prepared through anionic living polymerization. According to the process, shutdown for kettle cleaning is not needed, the low cis-polybutadiene, the solution polymerized styrene-butadiene and the hydroxyl-terminated liquid polybutadiene rubber can be produced on the same polymerization device in a flexible switching manner, and the overall production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer synthesis, in particular to a flexible switching production method and equipment for low cis-polybutadiene rubber, solution-polymerized styrene-butadiene rubber and hydroxyl-terminated liquid polybutadiene rubber. BACKGROUND

[0002] In the field of high polymer synthesis, low cis-polybutadiene rubber, solution-polymerized styrene-butadiene rubber and hydroxyl-terminated liquid polybutadiene rubber are three key synthetic rubber and polymer products, and their production and performance optimization have always been at the forefront of industry research and development. However, their production technology still faces a series of challenges, especially when trying to produce in a co-line to improve device utilization and economic benefits.

[0003] Currently, due to the difference in the selection of solvent systems and additives, it is difficult to seamlessly switch between the production of low cis-polybutadiene rubber and solution-polymerized styrene-butadiene rubber on the same production line, especially the residual tetrahydrofuran in the production of solution-polymerized styrene-butadiene rubber and the strict requirements on solution viscosity and gel content in the production of low cis-polybutadiene rubber, which limit the flexible production of the two materials. The mature production process of hydroxyl-terminated liquid polybutadiene rubber is mainly based on free radical polymerization, and its polymerization mechanism and solvent system are completely different from those of anionic polymerization process. Therefore, a solvent refining unit needs to be independently constructed for the production device of hydroxyl-terminated liquid polybutadiene rubber, and the structure and size design of the polymerization kettle are also different from those of solution-polymerized styrene-butadiene rubber, which cannot realize flexible switching production in the same production device. Moreover, the traditional production method of hydroxyl-terminated liquid polybutadiene rubber uses free radical polymerization, which leads to defects in the control of product relative molecular mass distribution, functional group distribution and microstructure. The capacity bottleneck of this process also leads to high price and limited market promotion, which is not conducive to its wide application in civilian fields.

[0004] Although the industry has a flexible production line for low cis-polybutadiene rubber and solution-polymerized styrene-butadiene rubber, there are still significant compatibility problems between the two rubber production processes. The gel inhibitor 1,2-butadiene used in the production of low cis-polybutadiene rubber will interfere with the chain end modification and coupling reaction of solution-polymerized styrene-butadiene rubber, and tetrahydrofuran in the solution-polymerized styrene-butadiene rubber system as an active regulator is difficult to remove effectively by conventional distillation due to its similar boiling point with n-hexane / cyclohexane mixed solvent, which seriously affects the microstructure control of low cis-polybutadiene rubber.

[0005] In the existing production strategy, in order to realize the co-line production of different kinds of rubber, it is often necessary to make large-scale adjustments or even modifications to the production equipment, such as adding a large amount of solvent refining units, which not only increases energy consumption, but also significantly increases capital investment, hindering the practice of efficient and economic co-line production. SUMMARY

[0006] The present application aims to solve the above problems, by optimizing the cyclohexane / n-hexane mixed solvent ratio, using solvation to regulate the stretched state of the polymer chain, reducing the viscosity of the polymerization system under the premise of not causing phase separation, reducing the amount of 1,2-butadiene and maintaining low gel content; design a new type of protecting group initiator sodium tert-butyl dimethyl siloxy propyl, prepare hydroxyl-terminated liquid polybutadiene rubber with controllable structure by anionic living polymerization. The process makes full use of the raw material homology, process similarity and solvent system compatibility of low cis-polybutadiene rubber, solution-polymerized styrene-butadiene rubber and hydroxyl-terminated liquid polybutadiene rubber, realizes flexible switching production of the three rubbers and their high value-added grades in the same device, does not need to stop and clean the tank, significantly reduces the production cost, and improves the production efficiency and safety.

[0007] To achieve the above purpose, the present application provides a flexible switching production method of low cis-polybutadiene rubber, solution-polymerized styrene-butadiene rubber and hydroxyl-terminated liquid polybutadiene rubber, which is carried out in a flexible switching production device, the flexible switching production device comprises a polymerization unit and an initiator preparation unit, and the flexible switching production method comprises the following steps: Cyclohexane and n-hexane are mixed in a volume ratio of 6.5:3.5-7:3 to form a mixed solvent; a new type of protecting initiator sodium tert-butyl dimethyl siloxy propyl is prepared; monomers, active agents, n-butyllithium or functionalized initiators, and mixed solvents are added to the polymerization kettle of the polymerization unit to carry out polymerization reaction, and low cis-polybutadiene rubber, solution-polymerized styrene-butadiene rubber or hydroxyl-terminated liquid polybutadiene rubber glue liquid is obtained; wherein the monomers include at least one of butadiene and styrene; the active agent is 2,2-di(2-tetrahydrofurfuryl)propane; in the polymerization unit, when preparing the hydroxyl-terminated liquid polybutadiene rubber, the initiator is sodium tert-butyl dimethyl siloxy propyl, and when preparing the low cis-polybutadiene rubber and solution-polymerized styrene-butadiene rubber, the initiator is n-butyllithium; the initiator production device comprises a preparation tank, a reaction kettle, a buffer tank and a filter; the initiator production device is connected with the polymerization unit.

[0008] Further, the initiator sodium tert-butyl dimethyl siloxy propyl is prepared by the following steps: tert-butyl dimethyl chlorosilane and imidazole solid powder are quickly stirred in cyclohexane to form a suspension; chloro-1-propanol is added to the suspension to generate tert-butyl dimethyl siloxy chloropropane; sodium metal particles suspended in cyclohexane after melting and rapid cooling are reacted with the tert-butyl dimethyl siloxy chloropropane to generate sodium tert-butyl dimethyl siloxy propyl; Further, in the polymerization unit, when preparing low syndiotactic polybutadiene rubber, the refined mixed solvent, butadiene, n-butyllithium are pumped into the polymerization kettle through the metering tank, stirred and mixed uniformly, and polymerized; and / or when preparing solution polymerized styrene-butadiene rubber, the refined mixed solvent, butadiene, styrene, n-butyllithium are pumped into the polymerization kettle through the metering tank, stirred and mixed uniformly, and polymerized; and / or when preparing hydroxyl-terminated liquid polybutadiene rubber, the refined mixed solvent, butadiene, sodium tert-butyldimethylsiloxypropyl are pumped into the polymerization kettle through the metering tank, stirred and mixed uniformly, and polymerized.

[0009] Further, the flexible switching production device further comprises a solvent refining unit, a butadiene refining unit, and a styrene refining unit; the solvent mixture obtained by flashing the low syndiotactic polybutadiene rubber, solution polymerized styrene-butadiene rubber, and hydroxyl-terminated liquid polybutadiene rubber obtained by polymerization reaction is sent to the solvent refining unit; the mixed solvent, butadiene, and styrene recovered from the refining unit are sent to the polymerization unit.

[0010] Further, in the solvent refining unit, the solvent mixture is sequentially sent to a water washing tower, a dehydration tower, a three-stage heavy component removal tower, and a residual liquid recovery tower for a solvent refining process; in the butadiene refining unit, butadiene is sequentially sent to a water washing tower, a dehydration tower, and a heavy component removal tower for a refining process; in the styrene refining unit, styrene is sequentially sent to a water washing tower, a dehydration tower, and a heavy component removal tower for a refining process.

[0011] Further, the flexible switching production device further comprises a polymerization aid preparation system, which is part of the polymerization unit and is used to prepare and add polymerization aids to the polymerization kettle; the polymerization aids include one or more of 2,2-di(2-tetrahydrofuryl)propane, 1,2-butadiene, ethylene oxide, silicon tetrachloride, piperidine, hexamethylene diisocyanate, 2-ethylhexanoic acid, and an antioxidant.

[0012] Further, the flexible switching production device further comprises a rubber solution flashing system; in the rubber solution flashing system, the rubber solution in the polymerization kettle is pumped into a flashing tank, the solvent flashing gas is condensed and pumped back to the polymerization kettle, and the concentrated rubber solution is pumped to the post-treatment unit.

[0013] Further, the flexible switching production device further comprises a post-treatment unit, in which the hydroxyl-terminated liquid polybutadiene rubber is sequentially subjected to water washing treatment, three-stage flash drying treatment, and filling treatment; the low syndiotactic polybutadiene rubber or solution polymerized styrene-butadiene rubber is sequentially subjected to coagulation treatment, extrusion treatment, swelling drying treatment, fluidized bed drying treatment, and packaging treatment.

[0014] Furthermore, the post-processing unit includes a filling unit, which includes a three-stage flash drying device. Each flash drying device includes a preheater, a pressure regulating valve, a flash tank, a vapor-liquid separator, and a vapor phase condenser.

[0015] The present invention also provides a flexible switching production equipment, which adopts the flexible switching production method described above.

[0016] By adopting the technical solution of the present invention, the following technical effects can be achieved: 1. The technical challenge of HTPB functionalization initiators has been solved, enabling the production of HTPB through living polymerization mechanism, thereby improving the controllability of the product's molecular weight distribution, functional group distribution, and microstructure. 2. It enabled the co-line production of SSBR, LCBR and HTPB, reducing production costs and improving production efficiency and safety; 3. Reduced production energy and material consumption, especially in the flash evaporation and solvent recovery stages. Through a solvent recovery strategy that returns the solvent to the polymerization reactor, and a multi-stage flash drying process, resources are effectively saved. 4. It has expanded the product range, especially for HTPB, enabling the production of more grades with narrow molecular weight distribution and excellent macroscopic properties, thus enhancing market competitiveness. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation process of different rubber adhesives according to the present invention; Figure 2 This is a schematic diagram of the polymerization unit of the present invention; Figure 3 This is a schematic diagram of the process flow of the post-processing unit of the present invention; Figure 4 This is a schematic diagram of the water washing process for hydroxyl-terminated liquid polybutadiene rubber. Figure 5 This is a schematic diagram of the primary drying process for hydroxyl-terminated liquid polybutadiene rubber. Figure 6 This is a schematic diagram of the two-stage drying process for hydroxyl-terminated liquid polybutadiene rubber. Figure 7 This is a schematic diagram of the three-stage drying process for hydroxyl-terminated liquid polybutadiene rubber.

[0018] Explanation of reference numerals in the attached figures: 02-Polymerization Unit; 31-Polymerization Reactor; 32-Polymerization Auxiliary Agent Preparation System; 33-Polymerization Auxiliary Agent Metering Tank; 34-Precooling / Preheating Heat Exchanger; 35-Adhesive Cooler; 41-Flash Tank; 42-First Adhesive Pump; 43-Static Mixer; 44-Washing Unit; 45-Three-Stage Flash Drying Unit; 46-Filling Unit; 47-Antioxidant Preparation System; 48-Coagulation Unit; 49-Extrusion Dehydrator; 50-Expansion Dryer; 51-Fluidized Bed; 52-Weighing / Blocking Unit; 53-Packaging Unit; 60-Process Water Flow Meter; 61-Washing Reactor; 62-Second Adhesive Pump; 63-First Aqueous Phase Buffer Tank; 64-First Water Pump; 65-Volatile De-Volatile Unit; 66-Wastewater Pipeline; 67-Metal Recovery Unit; 68-Second Water Pump; 69-Second Aqueous Phase Buffer Tank; 7 0 - Dilute sulfuric acid flow meter; 71 - Oil cooler for devolatilization unit; E-711 - Primary adhesive preheater; PV-711 - Primary pressure regulating valve; V-711 - Primary flash tank; P-711 - Primary adhesive pump; P-712 - Adhesive circulation pump; V-712 - Primary gas-liquid separator; E-712 - Primary vapor phase condenser; E-721 - Secondary adhesive preheater; PV-721 - Secondary pressure regulating valve; Secondary flash tank V-721; Secondary adhesive pump P-721; Secondary gas-liquid separator V-722; E-722 - Secondary vapor phase condenser; E-731 - Tertiary adhesive preheater; PV-731 - Tertiary pressure regulating valve; V-731 - Tertiary flash tank; P-731 - Tertiary adhesive pump; V-732 - Tertiary gas-liquid separator; E-732 - Tertiary vapor phase condenser. Detailed Implementation

[0019] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In existing technologies, the production of low-cis polybutadiene rubber, solution-polymerized styrene-butadiene rubber (SBR), and hydroxyl-terminated liquid polybutadiene rubber (PPB) requires independent production lines, which presents problems such as solvent system incompatibility and complex equipment modifications. Traditional processes use tetrahydrofuran as an activator in SBR production, leading to solvent residue. Switching between products necessitates cleaning the reaction unit and adjusting the solvent purification system, increasing energy consumption. Anionic polymerization of hydroxyl-terminated liquid PBR requires a dedicated initiator unit, increasing equipment investment costs. Switching between different rubber products also suffers from low equipment utilization and poor process flexibility.

[0021] Therefore, embodiments of the present invention provide a flexible switching production method for low-cis polybutadiene rubber, solution-polymerized styrene-butadiene rubber, and hydroxyl-terminated liquid polybutadiene rubber. This flexible switching production method is carried out in a flexible switching production equipment and includes the following steps: mixing cyclohexane and n-hexane at a volume ratio of 6.5:3.5-7:3 to form a mixed solvent; preparing a novel protective initiator, sodium tert-butyldimethylsiloxypropyl; adding the monomer, activator, initiator, and mixed solvent to the polymerization reactor 31 of polymerization unit 02 to carry out a polymerization reaction, yielding... The polymer unit 02 is used to produce low-cis polybutadiene rubber, solution-polymerized styrene-butadiene rubber, or hydroxyl-terminated liquid polybutadiene rubber; wherein the monomer includes at least one of butadiene and styrene; the activator is 2,2-bis(2-tetrahydrofuranyl)propane; in polymerization unit 02, when preparing hydroxyl-terminated liquid polybutadiene rubber, the initiator is sodium tert-butyldimethylsiloxypropyl; when preparing low-cis polybutadiene rubber or solution-polymerized styrene-butadiene rubber, the initiator is n-butyllithium; the initiator production device includes a preparation tank, a reaction vessel, a buffer tank, and a filter; the initiator production device is connected to polymerization unit 02.

[0022] like Figure 1 As shown, the flexible switching production method allows for the switching of production of different types of rubber within the same production equipment according to demand. This includes methods such as low-cis polybutadiene rubber, solution-polymerized styrene-butadiene rubber, and hydroxyl-terminated liquid polybutadiene rubber. This flexibility makes the production process more efficient and adaptable to changes in market demand. Flexible switching refers to the ability to flexibly adjust the type of rubber produced within the same production process as needed. This technology breaks through the traditional single-production-line model, enabling more efficient production of multiple types of rubber and reducing equipment downtime and resource waste.

[0023] Specifically, this invention optimizes the cyclohexane / n-hexane mixed solvent ratio to 6.5:3.5-7:3, utilizing solvation to regulate the stretching state of the polymer chains. This reduces the viscosity of the polymerization system without phase separation, thereby decreasing the amount of 1,2-butadiene and maintaining a low gel content. The mixed solvent, through precise proportioning, forms a unified solvent system that satisfies the solubility requirements of butadiene in low-cis polymerization while also being compatible with the reaction conditions during styrene copolymerization. The initiator production unit alternately prepares n-butyllithium and tert-butyldimethylsiloxypropyl sodium through independent reaction modules. After temporary storage in the initiator preparation system, the initiator is delivered to the polymerization reactor 31 as needed via an initiator metering tank.

[0024] In some embodiments of this application, the technical bottleneck of functionalized initiators for the preparation of hydroxyl-terminated liquid polybutadiene rubber by anionic active polymerization has been overcome. A novel initiator, sodium tert-butyldimethylsiloxypropyl, is prepared, which possesses high solubility in nonpolar solvents, room temperature stability, and high initiation activity. This allows hydroxyl-terminated liquid polybutadiene rubber to be produced using an anionic polymerization process similar to solution-polymerized styrene-butadiene rubber and low-cis polybutadiene rubber, enabling flexible switching of production on the same equipment.

[0025] Specifically, the protective initiator production unit includes a 200L preparation tank A, a 200L preparation tank C, a 1 cubic meter reactor A, a 1 cubic meter buffer tank A, a 1 cubic meter reactor B, a 1 cubic meter buffer tank B, and a filter. These units are first subjected to 24 hours of oil transport, followed by purging with 99.999% high-purity nitrogen. Reactor B is then purged with 99.999% argon gas until the oxygen levels in the water inside the tanks are below 10 ppm.

[0026] Specifically, the preparation steps of the initiator sodium tert-butyldimethylsiloxypropyl in this embodiment are as follows: In preparation tank A, tert-butyldimethylchlorosilane is diluted to a specific concentration using a refined mixed solvent, and then injected into reactor A under high-purity nitrogen atmosphere and high-pressure nitrogen gas, and stirring is started; a certain amount of imidazole compound crystalline powder is weighed and poured into reactor A through the solid feed port above reactor A, while simultaneously accelerating the stirring speed to rapidly and uniformly disperse the imidazole solid powder in the cyclohexane solution of tert-butyldimethylchlorosilane to form a suspension; in preparation tank B, chloro-1-propanol is diluted to a specific concentration using a refined mixed solvent, and then slowly added to reactor A over 30 minutes using a metering pump, ensuring that the temperature inside the reactor does not exceed 40°C during the reaction, and stirring is continued for 30 minutes after the addition is completed; while stirring, the suspension in reactor A is pumped out using a centrifugal pump and passed through a two-stage filter to allow the imidazole-hydrogen chloride complex solid particles to pass through... The metal filter screen is retained in the filter, while the cyclohexane solution of tert-butyldimethylsiloxychloropropane is stored in buffer tank A for later use. Sodium metal is added to reactor B through the solid feed port, along with a refined mixed solvent that covers the stirring paddle. Under argon protection, the material inside the reactor is heated to 100°C, and the nitrogen pressure is maintained at 0.4 MPa for 90 minutes to melt the sodium metal. Stirring is accelerated to ensure the sodium metal is evenly distributed in small droplets. After 20 minutes, the steam heating process is shut off, and after another 20 minutes, the circulating water cooling process is started until the reactor temperature drops to 60°C. Using a metering pump, the cyclohexane solution of tert-butyldimethylsiloxychloropropane from buffer tank A is slowly added to reactor B over 60 minutes, ensuring the reactor temperature does not exceed 40°C during the reaction. After the addition is complete, the 5°C low-temperature water cooling process is started, and the reaction is continued with stirring for another 60 minutes, ultimately yielding sodium tert-butyldimethylsiloxypropyl.

[0027] It should be noted that after the feeding process of pouring the solid feed into reactor B through the solid feed port above reactor B is completed, the air introduced during the feeding process is replaced with 99.999% argon gas to a level below 10 ppm. The initiator concentration of sodium tert-butyldimethylsiloxypropyl is 0.5 mol / L.

[0028] Specifically, after the reaction is complete, the product is discharged from the bottom valve of reactor B and transferred to buffer tank B via a discharge pump. Buffer tank B, under high-purity nitrogen protection, is used to store the initiator solution. Reactor B has four layers of metal mesh screens with different mesh sizes at its bottom to ensure effective separation of sodium metallic particles and sodium chloride particles. The sodium chloride and imidazole-hydrogen chloride complex generated during the reaction are treated as solid waste. The sodium metallic particles and sodium chloride particles separated by the metal mesh screens are periodically replaced to remove sodium chloride byproducts.

[0029] Through the above steps, the protecting group initiator sodium tert-butyldimethylsiloxypropyl sodium was successfully prepared and stored, providing a key functionalizing initiator for subsequent polymerization reactions. This process requires strict control of reaction conditions, including temperature, pressure, solvent, and atmospheric purity, to ensure the activity of the initiator and the quality of the product.

[0030] In some embodiments of this application, such as Figure 2 As shown, polymerization unit 02 includes a polymerization kettle 31, a polymerization aid preparation system 32, a polymerization aid metering tank 33, a precooling / preheating heat exchanger 34, and a rubber solution cooler 35. This process involves adding butadiene monomer or styrene monomer, a mixed solvent, and an initiator to the polymerization kettle 31 of polymerization unit 02 for polymerization, thereby producing different types of rubber solutions. In polymerization unit 02, a technical solution for flexibly switching between three rubber products is achieved by setting the raw material combination and initiator selection according to the type of polymerization reaction: when preparing low-cis polybutadiene rubber, refined mixed solvent, butadiene, and n-butyllithium are pumped to polymerization kettle 31 through polymerization aid metering tank 33 for polymerization; when preparing solution-polymerized styrene-butadiene rubber, mixed solvent, butadiene, styrene, and n-butyllithium are pumped to polymerization kettle 31 through metering tank for polymerization; when preparing hydroxyl-terminated liquid polybutadiene rubber, mixed solvent, butadiene, and sodium tert-butyldimethylsiloxypropyltrimonium are pumped to polymerization kettle 31 through polymerization aid metering tank 33 for polymerization. The precooling / preheating heat exchanger 34 adjusts the material temperature according to the polymerization type. For example, in the production of hydroxyl-terminated liquid polybutadiene rubber, it preheats the mixture to the initiator activation temperature, and in the production of solution-polymerized styrene-butadiene rubber, it precools to control the reaction initiation rate. The liquid cooler 35 is introduced in the later stage of the reaction to control the molecular weight distribution of the product through gradient cooling.

[0031] Specifically, polymerization unit 02 includes a 15 cubic meter polymerization reactor, a polymerization aid preparation system 32, a flow meter, a polymerization aid metering tank 33, and a liquid cooler 35. The polymerization aid metering tank 33 includes an initiator metering tank, an activator metering tank, a gel inhibitor metering tank, a capping agent metering tank, a coupling agent metering tank, a chain end modifier A metering tank, a chain end modifier B metering tank, and a terminator metering tank. The refined mixed solvent is adjusted to the required temperature through the flow meter and the polymerization aid metering tank 33, and then pumped into the polymerization reactor 31. Simultaneously, refined butadiene is pumped into the polymerization reactor 31 through the flow meter, and then stirring is started to ensure uniform mixing. The polymerization aids required for the polymerization reaction are metered by volume through the aid metering tank above the polymerization reactor 31 and then pressurized into the polymerization reactor 31 with nitrogen gas. Finally, the initiator is metered by volume through the initiator metering tank above the polymerization reactor 31 and then pressurized into the polymerization reactor 31 with nitrogen gas, and polymerization is started.

[0032] It should be noted that the polymerization of solution-polymerized styrene-butadiene requires initiating the feeding process of refined styrene; depending on the formulation design, activators may be added; a gel inhibitor is required when polymerizing low-cis polybutadiene rubber, and chain-end modifier A is required when polymerizing solution-polymerized styrene-butadiene; low-cis polybutadiene rubber or solution-polymerized styrene-butadiene uses n-butyllithium as an initiator, while hydroxyl-terminated liquid polybutadiene rubber requires initiating the feeding process of the protective initiator sodium tert-butyldimethylsiloxypropyltrimonium. All polymerization auxiliaries are metered and added to the polymerization reactor 31 via an auxiliary metering tank.

[0033] The polymerization process shares the same polymerization reactor 31 and temperature control system. The production line can be quickly switched by changing the material conveying path and the type of initiator. The fixed ratio design of the mixed solvent avoids the need for equipment cleaning due to changes in the solvent system.

[0034] In some embodiments of this application, the flexible switching production equipment further includes a solvent refining unit, a butadiene refining unit, and a styrene refining unit; the solvent mixture obtained by flash evaporation of the low-cis polybutadiene rubber, solution-polymerized styrene-butadiene rubber, and hydroxyl-terminated liquid polybutadiene rubber obtained from the polymerization reaction is fed into the solvent refining unit; the mixed solvent, butadiene, and styrene recovered from the refining unit are fed into the polymerization unit 02.

[0035] The solvent refining unit is a device for purifying the solvent mixture formed after the polymerization reaction. Specifically, it can employ a refining process consisting of a water washing tower, a dehydration tower, a three-stage deweighting tower, and a residual liquid recovery tower. By removing residual activators, unreacted monomers, and high-boiling-point byproducts stage by stage, it ensures that the purity of the recovered solvent meets the production requirements of different rubber products. The butadiene refining unit is a device for the targeted purification of butadiene monomers. Specifically, it can employ a water washing, dehydration, and deweighting process to avoid residual impurities in butadiene affecting the polymerization reaction activity during product switching. The styrene refining unit is a device for the targeted purification of styrene monomers. Specifically, it can employ an independent water washing, dehydration, and deweighting process to eliminate cross-contamination caused by trace amounts of solvents or other monomers that may be mixed into the styrene.

[0036] Specifically, the mixed solvent, after flash evaporation, enters the solvent refining unit. Water-soluble impurities are removed by washing, free water is separated in a dehydration tower, heavy components are gradually removed in a three-stage de-heavyness tower, and the solvent is further purified in a residual liquid recovery tower. The refined mixed solvent is returned to polymerization unit 02 for recycling, preventing uncontrolled polymerization reactions caused by impurity accumulation. The butadiene refining unit and the styrene refining unit process the two monomers independently, achieving directional refining through modular design. This prevents styrene residue from contaminating either butadiene or styrene, ensuring that monomer purity meets the polymerization requirements of different rubbers during production switchovers. Each refining unit and polymerization unit 02 form a closed-loop material circulation system, reducing solvent and monomer consumption.

[0037] By setting up independent solvent, butadiene, and styrene refining units, different materials can be processed in stages to avoid cross-contamination. This enables efficient recycling of mixed solvents and monomers. At the same time, the modular design allows for adaptation to the refining needs of different products without modifying existing equipment, significantly reducing production changeover time and energy consumption.

[0038] In some embodiments of this application, in the solvent refining unit, the mixed solvent is sequentially fed into a water washing tower, a dehydration tower, a three-stage de-heavy removal tower, and a residual liquid recovery tower for solvent refining; in the butadiene refining unit, butadiene is sequentially fed into a water washing tower, a dehydration tower, and a de-heavy removal tower for refining; and in the styrene refining unit, styrene is sequentially fed into a water washing tower, a dehydration tower, and a de-heavy removal tower for refining.

[0039] Specifically, the mixed solvent first enters a water washing tower to remove water-soluble impurities such as alcohols, amines, and ethers. It then enters a dehydration tower for azeotropic distillation to remove trace amounts of water. The purified solvent, free of water and light component impurities after the first two steps, enters a three-stage de-heavy solvent tower. The purified solvent exits from the top of the three-stage de-heavy solvent tower, is condensed and liquefied in the de-heavy solvent tower condenser, and then enters the de-heavy solvent tower reflux tank. A portion of the purified solvent in the reflux tank is pumped back to the three-stage de-heavy solvent tower by the de-heavy solvent tower reflux pump at a specific reflux ratio, while a portion is pumped into the purified solvent storage tank for later use. The solvent containing heavy components from the bottom of the de-heavy solvent tower sequentially enters the next stage of the de-heavy solvent tower. Finally, the bottom liquid from the third-stage de-heavy solvent tower is pumped into the residue recovery tower by the bottom liquid pump of the third-stage de-heavy solvent tower. The recovered solvent from the residue recovery tower exits from the top of the tower, is condensed and liquefied in the residue recovery tower condenser, and then enters the residue recovery tower reflux tank. Finally, the residue recovery tower reflux pump pumps all of it back to the first de-heavy solvent tower for further de-heavy solvent removal. The residual liquid in the bottom of the residual liquid tower is pumped into the residual liquid tank by the residual liquid tower bottom liquid pump in preparation for loading.

[0040] Specifically, during butadiene refining, a water washing tower removes water-soluble impurities such as alcohols, amines, and ethers, and then the product enters a dehydration tower. Water and other light component impurities exit from the top of the dehydration tower, are condensed and liquefied in the dehydration tower condenser, and then enter the dehydration tower reflux tank. The water separated from the dehydration tower is channeled into the wastewater network via the water separator in the dehydration tower reflux tank, while the butadiene is entirely pumped back to the dehydration tower by the dehydration tower reflux pump. Butadiene free of water and light impurities is pumped from the bottom of the dehydration tower into the butadiene de-weighting tower via a bottom pump. Refined butadiene exiting the top of the de-weighting tower is condensed and liquefied in the condenser before entering the reflux tank. A portion of the refined butadiene in the reflux tank is pumped back to the de-weighting tower by a reflux pump at a specific reflux ratio, while the remainder is pumped into a refined butadiene storage tank for later use. Butadiene containing heavy components from the bottom of the de-weighting tower is pumped into a residual liquid tank by a bottom pump and mixed with residual solvent before loading.

[0041] Specifically, in the styrene refining process, a water washing tower removes water-soluble impurities such as alcohols, amines, and ethers, and then the product enters a dehydration tower. Water and other light component impurities leave the top of the dehydration tower, are condensed and liquefied in the dehydration tower condenser, and then enter the dehydration tower reflux tank. The water separated from the dehydration tower is discharged into the wastewater network through the water separator in the dehydration tower reflux tank, while the styrene is entirely pumped back to the dehydration tower by the dehydration tower reflux pump. Styrene free of water and light component impurities is pumped from the bottom of the dehydration tower into the styrene de-heavy tower by the dehydration tower bottom liquid pump. Refined styrene leaves the top of the de-heavy tower, is condensed and liquefied in the de-heavy tower condenser, and then enters the de-heavy tower reflux tank. A portion of the refined styrene in the de-heavy tower reflux tank is pumped back to the de-heavy tower by the de-heavy tower reflux pump at a certain reflux ratio, while a portion is pumped into a refined butadiene storage tank for later use by the withdrawal pump. The styrene containing heavy components in the bottom of the de-heavy tower is pumped into the residual liquid tank by the bottom liquid pump of the de-heavy tower to be mixed with the solvent residue in preparation for loading.

[0042] All three refining units employ a standardized process of washing, dehydration, and deweighting, ensuring structural compatibility of the refining equipment for different monomers and eliminating the need for equipment replacement during production line switchovers. The solvent refining unit achieves gradient separation of heavy components through the synergistic effect of a three-stage deweighting tower and a residual liquid recovery tower.

[0043] In some embodiments of this application, the flexible switching production equipment further includes a polymerization aid preparation system 32. The polymerization aid preparation system 32 is used to prepare and add polymerization aids to the polymerization reactor 31. The types of aids that can be prepared and added include, but are not limited to, surfactants, gel inhibitors, end-capping agents, coupling agents, chain-end modifiers, terminators, and antioxidants. The polymerization aids include one or more of 2,2-di(2-tetrahydrofuranyl)propane, 1,2-butadiene, ethylene oxide, silicon tetrachloride, piperidine, hexamethylene diisocyanate, 2-ethylhexanoic acid, and antioxidants. All polymerization aids are liquids at room temperature and are equipped with independent preparation and metering tanks.

[0044] Specifically, the polymerization aid preparation system 32 achieves independent storage and precise metering of different aids through the polymerization aid metering tank 33. Taking the surfactant 2,2-bis(2-tetrahydrofuranyl)propane as an example, the preparation process is as follows: The polymerization aid preparation tank and the polymerization aid metering tank 33 are first transported by oil for 24 hours, and then purged with 99.999% high-purity nitrogen until the water and oxygen values ​​in the tanks are both below 10 ppm. The liquid surfactant is pumped into the 1 cubic meter preparation tank using a diaphragm pump under nitrogen protection. Then, the required dose of 2,2-bis(2-tetrahydrofuranyl)propane is metered into the polymerization reactor 31 through the surfactant metering tank in the polymerization aid metering tank 33. The preparation process for other aids such as gel inhibitors and ethylene oxide is similar.

[0045] In the production stage of low-cis polybutadiene rubber, the activity of the polymerization reaction is controlled by adding 2,2-bis(2-tetrahydrofuranyl)propane to polymerization reactor 31 through an activator preparation system and an activator metering tank, thereby increasing the cis structure content of the polymer. 1,2-Butadiene is added through a gel inhibitor metering tank to reduce gel formation during polymerization and improve rubber properties. During or in the later stages of polymerization, a star-shaped coupling agent, silicon tetrachloride, can be added through a coupling agent metering tank to prepare low-cis polybutadiene rubber with a star-branched structure. After the polymerization reaction is complete, a terminator, such as 2-ethylhexanoic acid, needs to be added to polymerization reactor 31 through a terminator metering tank to terminate the reaction.

[0046] In the solution polymerization stage of styrene-butadiene rubber (SSBR), 2,2-bis(2-tetrahydrofuranyl)propane (DTHFP) is used as an activator. After being metered in the activator preparation system, it is added to the polymerization reactor 31 via nitrogen pressure or pumping. Piperidine is used as chain-end modifier A to regulate the chain-end structure of SSBR. It is added to the polymerization reactor 31 through the chain-end modifier A preparation system and the chain-end modifier A metering tank. Depending on the formulation requirements, silicon tetrachloride is added as a coupling agent, or hexamethylene diisocyanate is added as chain-end modifier B. These act in the later stages of the polymerization process to regulate the polymer's microstructure and are added to the polymerization reactor 31 through the corresponding preparation system and metering tank. After the polymerization reaction is complete, a terminator, such as 2-ethylhexanoic acid, is added to the polymerization reactor 31 through the terminator metering tank to terminate the reaction.

[0047] In the production stage of hydroxyl-terminated liquid polybutadiene rubber, ethylene oxide is used as a polymerization aid to block the hydroxyl groups at the end of the polybutadiene chain. It is pumped into the polymerization reactor 31 through the end-capping agent preparation system and the end-capping agent metering tank.

[0048] These polymerization auxiliaries are formulated using the polymerization auxiliary formulation system 32 to ensure they reach the required concentration and state before being added to the polymerization reactor 31, thereby controlling the reaction conditions and achieving production targets. After formulation, the auxiliaries are precisely metered via the polymerization auxiliary metering tank 33 and added to the polymerization reactor 31 of polymerization unit 02 via nitrogen pressure or pumping to participate in the reaction process. Furthermore, antioxidants can also be added to the rubber solution during post-processing using the antioxidant formulation system 47 to further enhance the performance of the rubber product.

[0049] The formulation of polymerization auxiliaries is based on the principles of metering and mixing, enabling precise formulation and addition of various polymerization auxiliaries, thereby achieving precise control over polymerization reaction conditions. Using a polymerization auxiliary formulation system can improve the formulation accuracy and addition efficiency of auxiliaries, thus improving the performance of rubber products and production efficiency. In other embodiments, the formulation accuracy and addition efficiency of auxiliaries can be further improved by optimizing the design and operating parameters of the auxiliary formulation system to meet the needs of different rubber products.

[0050] In some embodiments of this application, a flash evaporation system for adhesives is provided in the flexible switching production equipment. The adhesive in the polymerization reactor 31 is transported to the flash tank 41, the mixed solvent is returned to the polymerization reactor 31 after flash vaporization and condensation, and the concentrated adhesive is pumped to the post-processing unit.

[0051] Specifically, the solvent in polymerization reactor 31 is pumped into a 30 cubic meter flash tank 41 using a solvent circulation pump. The solvent rapidly flashes and vaporizes, rising to the top of the tank where a vertically arranged gas-phase condenser condenses and liquefies the solvent, which then flows into a 1 cubic meter solvent collection tank. The solvent is then pumped back into the polymerization reactor 31 via a solvent pump into a solvent cooler 35. Non-condensable gases are sent to the RTO waste gas treatment system. The concentrated solvent is pumped to the post-treatment unit. In this embodiment, the solvent can be returned to the polymerization reactor 31, reducing energy and material consumption.

[0052] Specifically, the flash-evaporated adhesive solution can be pumped together with the antioxidant and then mixed evenly in the static mixer 43. The antioxidant can be added to the discharge line of the polymerization reactor 31 and mixed evenly in the static mixer 43 before entering the water washing unit 44 or the coagulation unit 48 for further processing.

[0053] In some embodiments of this application, the flexible switching production equipment further includes a post-processing unit. In the post-processing unit, hydroxyl-terminated liquid polybutadiene rubber is sequentially subjected to water washing, three-stage flash drying, and filling; low-cis polybutadiene rubber or solution-polymerized styrene-butadiene rubber is sequentially subjected to coagulation, extrusion, expansion drying, fluidized bed drying, and packaging. The three-stage flash drying unit 45 in the post-processing unit includes a three-stage flash drying device, each of which includes a preheater, a pressure regulating valve, a flash tank 41, a vapor-liquid separator, and a vapor-phase condenser.

[0054] like Figure 4As shown, the hydroxyl-terminated liquid polybutadiene rubber solution polymerized in polymerization unit 02 is sent to a 30 cubic meter water washing tank 61. Then, the process water flow meter 60 is turned on, and deionized water is added at a water-to-resin ratio of 1:1. Stirring is started to ensure thorough mixing of the solution and deionized water. Then, a small amount of 10% dilute sulfuric acid solution is added to the dilute sulfuric acid flow meter 70 to adjust the pH of the water-resin system to 6-7. After settling and separating, the lower aqueous phase enters the first aqueous phase buffer tank 63 and is pumped into the sewage network 66 by the first water pump 64. The upper layer of solution remains in the water washing tank 61. The water washing process is repeated by adding deionized water at a water-to-resin ratio of 1:1 and stirring. Finally, the solution is allowed to settle and separate. The lower aqueous phase is pumped into the sewage network 66, and the upper layer of solution is pumped to the devolatilization unit 65 by the second solution pump 62. The liquid after passing through the first water pump 64 also passes through the metal recovery unit 67 to recover lithium metal from the liquid. The recovered liquid is stored in the second aqueous phase buffer tank 69 and is then returned to the washing tank 61 or the sewage network 66 by the second water pump 68. The flash vapor solvent in the washing step enters the oil cooler 71 of the devolatilization unit from the washing tank. This washing step can remove residual metals from the adhesive solution to less than 20 ppm.

[0055] like Figure 3 , 5 As shown, the hydroxyl-terminated liquid polybutadiene rubber solution, after passing through the water washing unit 44, first passes through the primary solution preheater E-711. The primary solution preheater E-711 is equipped with a steam condensate tank and a condensate pump. After preheating, the outlet pressure is regulated by the primary pressure regulating valve PV-711 and then enters the primary flash tank V-711. The flash vapor phase passes through the primary gas-liquid separator V-712 and enters the primary gas phase condenser E-712 for condensation and liquefaction before being sent to the solvent refining unit for recovery. The primary concentrated solution is pumped by the primary solution pump P-711 and enters the secondary drying process.

[0056] like Figure 6 As shown, the liquid rubber after primary drying is preheated by secondary rubber preheater E-721, which is equipped with a steam condenser tank and a condenser pump. After preheating, the liquid rubber enters the secondary flash tank V-721 after the outlet pressure is regulated by the secondary pressure regulating valve PV-721. The secondary flash vapor phase enters the secondary vapor phase condenser E-722 through the secondary gas-liquid separator V-722 and is then condensed and liquefied before being sent to the solvent refining unit for recovery. The secondary concentrated rubber is pumped by the secondary rubber pump P-721 and enters the tertiary drying process.

[0057] It should be noted that if the volatile content of the rubber solution after the second-stage flash evaporation is too high, the rubber solution circulation pump P-712 should be turned on to return the rubber solution to the first-stage flash tank V-711 to extend the residence time.

[0058] like Figure 7As shown, the liquid rubber after secondary drying is preheated by the tertiary adhesive preheater E-731, which is equipped with a steam condenser tank and a condenser pump. After preheating, the liquid rubber enters the tertiary flash tank V-721 after the outlet pressure is regulated by the secondary pressure regulating valve PV-721. The tertiary flash vapor phase enters the tertiary gas phase condenser E-732 through the tertiary gas-liquid separator V-732 and is then condensed and liquefied before being sent to the solvent refining unit for recycling. After the tertiary concentrated adhesive is sampled and the volatile content is tested and found to be qualified, it can enter the subsequent filling unit 46 for packaging and warehousing.

[0059] For hydroxyl-terminated liquid polybutadiene rubber, three-stage flash evaporation can completely remove residual solvent. For low-cis polybutadiene rubber or solution-polymerized styrene-butadiene rubber, the rubber solution after preliminary flash evaporation enters the coagulation unit 48. Specifically, the low-cis polybutadiene rubber or solution-polymerized styrene-butadiene rubber solution enters the coagulation system to separate the rubber from the solution, and the solvent is recovered and sent to the solvent refining unit for recycling. Then, the water-containing rubber particles enter the extrusion dewatering machine 49 for preliminary dehydration. Next, the rubber particles enter the expansion dryer 50 for expansion drying to remove most of the moisture. Finally, the rubber particles enter the fluidized bed 51 for further drying until the volatile matter content meets the requirements. The qualified dried rubber particles are then packaged and stored in the packaging unit 53 after passing through the weighing / blending unit 52. The modular combination of equipment in each flash evaporation stage replaces the traditionally independently set drying and coagulation systems.

[0060] Embodiments of the present invention also provide a flexible switching production device, which employs the flexible switching production method described above.

[0061] Flexible switching production equipment enables seamless switching between different production modes. It encompasses not only the physical equipment itself but also the intelligent switching of operating processes. By combining flexible switching production methods, this equipment can adjust production methods, control parameters, and reaction conditions according to specific needs during production, thereby achieving a highly efficient and precise production process.

[0062] The versatility of flexible production equipment can significantly reduce investment costs. Furthermore, equipment capable of rapidly switching production modes helps improve production efficiency, reduce changeover time and unnecessary downtime, thereby lowering production costs.

[0063] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A flexible switching production process of low syndiotactic polybutadiene rubber, solution polybutadiene rubber and hydroxyl-terminated liquid polybutadiene rubber, characterized by, The flexible switching production method is performed in a flexible switching production device, the flexible switching production device comprises an initiator production device, a polymerization unit, and the flexible switching production method comprises the following steps: Cyclohexane and n-hexane are mixed in a volume ratio of 6.5:3.5-7:3 to form a mixed solvent; A novel protective initiator, sodium tert-butyl dimethyl silyloxy propyl, is prepared; The monomer, the active agent, the initiator, and the mixed solvent are added into a polymerization kettle 31 of the polymerization unit to perform a polymerization reaction, so as to obtain a low cis-polybutadiene rubber, a solution-polymerized styrene-butadiene rubber, or a hydroxyl-terminated liquid polybutadiene rubber; The monomer comprises at least one of butadiene and styrene; the active agent is 2,2-bis(2-tetrahydrofuryl)propane; when the hydroxyl-terminated liquid polybutadiene rubber is prepared, the initiator in the polymerization unit is the protective initiator, sodium tert-butyl dimethyl silyloxy propyl; when the low cis-polybutadiene rubber or the solution-polymerized styrene-butadiene rubber is prepared, the initiator is n-butyl lithium; The initiator production device comprises a preparation tank, a reaction kettle, a buffer tank, and a filter; the initiator production device is connected with the polymerization unit.

2. The flexible switching production method according to claim 1, characterized in that, The initiator, sodium tert-butyl dimethyl silyloxy propyl, is prepared by the following steps: Tert-butyl dimethyl chlorosilane and imidazole solid powder are rapidly stirred in a cyclohexane solution to form a suspension; Chloro-1-propanol is added into the suspension to generate tert-butyl dimethyl silyloxy chloropropyl; After sodium metal is melted and rapidly cooled, sodium metal particles are formed; the suspension of the sodium metal particles is reacted with the tert-butyl dimethyl silyloxy chloropropyl to generate sodium tert-butyl dimethyl silyloxy propyl.

3. The flexible switching production method according to claim 1, characterized in that, In the polymerization unit: When the low cis-polybutadiene rubber is prepared, the refined mixed solvent, butadiene, and n-butyl lithium are pumped into the polymerization kettle through a metering tank, are stirred and mixed uniformly, and are subjected to polymerization; and / or When the solution-polymerized styrene-butadiene rubber is prepared, the refined mixed solvent, butadiene, styrene, and n-butyl lithium are pumped into the polymerization kettle through a metering tank, are stirred and mixed uniformly, and are subjected to polymerization; and / or When the hydroxyl-terminated liquid polybutadiene rubber is prepared, the refined mixed solvent, butadiene, and the sodium tert-butyl dimethyl silyloxy propyl are pumped into the polymerization kettle through a metering tank, are stirred and mixed uniformly, and are subjected to polymerization.

4. The flexible switching production method according to claim 1, characterized in that, The flexible switching production device further comprises a solvent refining unit, a butadiene refining unit, and a styrene refining unit; a solvent mixture obtained by flashing the low cis-polybutadiene rubber, the solution-polymerized styrene-butadiene rubber, and the hydroxyl-terminated liquid polybutadiene rubber obtained through the polymerization reaction is sent into the solvent refining unit; the mixed solvent, butadiene, and styrene recovered from the refining unit are sent into the polymerization unit.

5. The flexible switching production method according to claim 4, characterized in that, In the solvent refining unit, the solvent mixture is sequentially sent into a water washing tower, a dehydration tower, a three-stage heavy component removal tower, and a residual liquid recovery tower to perform a solvent refining process; In the butadiene refining unit, butadiene is sequentially sent into a water washing tower, a dehydration tower, and a heavy component removal tower to perform a refining process; In the styrene refining unit, styrene is sequentially sent into a water washing tower, a dehydration tower, and a heavy component removal tower to perform a refining process.

6. The flexible switching production method according to claim 1, characterized in that, The flexible switching production device further comprises a polymerization aid preparation system, the polymerization aid preparation unit being part of the polymerization unit and being used for preparing and adding polymerization aids into the polymerization kettle; The polymerization aids comprise one or more of 2,2-di(2-tetrahydrofurfuryl)propane, 1,2-butadiene, ethylene oxide, silicon tetrachloride, piperidine, hexamethylene diisocyanate, 2-ethylhexanoic acid, and antioxidant.

7. The flexible switching production method according to claim 1, characterized in that, The flexible switching production device further comprises a glue liquid flash evaporation system; in the glue liquid flash evaporation system, glue liquid in the polymerization kettle is pumped into a flash tank, solvent flash evaporation gasification condensation is re-pumped back to the polymerization kettle, and concentrated glue liquid is pumped to a post-treatment unit.

8. The flexible switching production method according to claim 1, characterized in that, The flexible switching production device further comprises a post-treatment unit, in which the hydroxyl-terminated liquid polybutadiene rubber is sequentially subjected to water washing treatment, three-stage flash evaporation drying treatment, and filling treatment. Low cis-polybutadiene rubber or solution-polymerized styrene-butadiene rubber is sequentially subjected to coagulation treatment, extrusion treatment, swelling drying treatment, fluidized bed drying treatment, and packaging treatment.

9. The flexible switching production method according to claim 9, characterized in that, The post-treatment unit comprises a canning unit, and the canning unit comprises three-stage flash evaporation drying devices, each of which comprises a preheater, a pressure regulating valve, a flash tank, a vapor-liquid separator, and a gas phase condenser.

10. A flexible switching production device, characterized by The flexible switching production device adopts the flexible switching production method according to any one of claims 1-9.

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