Preparation method and system of butadiene-styrene latex for artificial turf back coating

Abstract

This application relates to the technical field of polymer material preparation, and in particular to a method and system for preparing styrene-butadiene latex for artificial turf back coating. The method includes: when the heating rate of the center temperature exceeds a preset rate threshold, and the temperature difference between the center temperature and the near-wall temperature exceeds a preset temperature difference threshold, and the normalized deviation coefficient exceeds a preset decoupling threshold, reducing the rotation speed of the inner stirrer, increasing the rotation speed of the outer stirrer, and switching the coolant to periodic on-off flow; during the speed adjustment period, if the real-time torque of the inner stirrer exceeds a preset sudden change threshold, pumping the mixture into the central region through an internal channel; when the heating rate and the normalized deviation coefficient fall back to a preset range, restoring the state before speed adjustment, and obtaining the styrene-butadiene latex. This application resolves the "heat-shear force decoupling" effect through multi-dimensional synergistic intervention, thereby effectively inhibiting boundary layer microgelation.

Description

Technical Field

[0001] This application relates to the technical field of polymer material preparation, and in particular to a method and system for preparing styrene-butadiene latex for back coating of artificial turf. Background Technology

[0002] Artificial turf is widely used in sports stadiums and landscaping. Its backing fabric requires an adhesive coating to fix the grass fibers and stabilize their dimensions, thus giving the turf good leveling properties, water resistance, and tear resistance. Styrene-butadiene rubber (SBR) latex, due to its excellent physical and mechanical properties and environmental friendliness, has become one of the most important water-based synthetic latexes in artificial turf backing processes. In practical applications, SBR latex for backing must possess excellent penetration and leveling properties to deeply penetrate the densely woven polypropylene or polyethylene backing fabric, while also requiring extremely high adhesion to firmly lock the grass fibers at the roots and prevent grass shedding during use. Therefore, extremely uniform particle size distribution of the latex is a key prerequisite for ensuring backing quality, which places extremely stringent requirements on the large-scale polymerization preparation process of SBR latex.

[0003] To improve the overall performance of latex used for backing artificial turf, the industry has explored numerous technologies. For example, Chinese invention patent announcement number CN103374090B discloses a method for preparing carboxylated styrene-butadiene latex for artificial turf backing using soap-free polymerization. This prior art uses butadiene and styrene as the main monomers, adds ethylene maleate, and completes the polymerization reaction using a batch-by-batch feeding and dripping method. After dripping, the reaction is kept at a constant temperature, and then transferred to a degassing reactor for reduced pressure flash degassing. This method, through a specific formulation and soap-free polymerization process, produces carboxylated styrene-butadiene latex that exhibits good elasticity, stiffness, bonding strength, and water resistance when used on artificial turf. This conventional polymerization preparation method, to a certain extent, meets environmental protection requirements and improves conventional physical properties.

[0004] However, the aforementioned existing technologies face a hidden and fatal core technical flaw when scaled up for mass production: during the exothermic peak of the polymerization reaction, they are highly susceptible to boundary layer microgelation caused by the decoupling of heat and shear force. In specific scenarios of large-scale production, when the polymerization reaction reaches its exothermic peak, the system typically requires full-operation jacket cooling to suppress the exothermic peak at the center of the reactor. Due to the non-Newtonian fluid characteristics of styrene-butadiene latex, the viscosity of the reaction liquid near the reactor wall increases sharply after rapid cooling, forming a highly viscous, cold boundary layer that is extremely difficult to flow. This boundary layer acts like an insulating blanket, completely blocking the effective heat transfer path from the central high-temperature reaction liquid to the reactor wall. At the same time, the shear force of a conventional agitator rapidly decays when attempting to penetrate this highly viscous boundary layer, resulting in the formation of localized high-temperature hot spots at the interface between the inner side of the boundary layer and the central reaction liquid that cannot be effectively stirred. Within this hot spot region, the monomer reaction rate becomes exponentially out of control, transiently triggering a large number of micro-gel clusters. These large-particle microgels, resulting from localized loss of control, mix into the finished latex. During subsequent artificial turf coating operations, they are trapped on the dense backing fabric surface, forming a pseudo-skin. This skinning phenomenon directly hinders the effective latex components from penetrating deeper, causing the grass fibers to remain suspended at the roots. Ultimately, this results in a wider particle size distribution of the artificial turf backing latex, extremely poor backing fabric permeability, and a precipitous drop in the pull-out strength of the finished turf, making it highly susceptible to grass shedding and other defects. Summary of the Invention

[0005] In order to resolve the "heat-shear force decoupling" effect through multi-dimensional synergistic intervention and thus effectively suppress boundary layer microgelation, this application provides a method and system for preparing styrene-butadiene latex for artificial turf back coating.

[0006] In a first aspect, this application provides a method for preparing styrene-butadiene latex for back coating of artificial turf, employing the following technical solution: A method for preparing styrene-butadiene latex for back coating of artificial turf, using a reaction vessel equipped with a jacket, an outer agitator, and an inner agitator with internal channels, the method comprising:

[0007] When the temperature of the reaction system is lower than the preset exothermic temperature, the torque of the outer and inner stirrers is collected to establish the outer reference torque and the inner reference torque.

[0008] When the temperature of the reaction system reaches the exothermic temperature, the center temperature of the central region of the reaction system, the near-wall temperature of the inner wall region of the reactor, and the real-time rotation speed and real-time torque of the outer and inner stirrers are obtained.

[0009] When the heating rate of the center temperature is greater than the preset rate threshold, and the temperature difference between the center temperature and the near-wall temperature is greater than the preset temperature difference threshold, and the normalized deviation coefficient determined by the real-time rotation speed, real-time torque and the corresponding reference rotation speed, reference torque is greater than the preset decoupling threshold, the rotation speed of the inner agitator is reduced, the rotation speed of the outer agitator is increased, and the coolant flowing into the jacket is switched to periodic opening and closing flow.

[0010] During the speed adjustment, if the real-time torque of the inner agitator is greater than the preset sudden change threshold, a mixture containing chain transfer agent and terminator is pumped into the central region through the internal channel.

[0011] When the heating rate and the normalized deviation coefficient fall back to the preset range, the state before the speed adjustment is restored, and styrene-butadiene latex is obtained.

[0012] Optionally, establishing the outer reference torque and the inner reference torque includes:

[0013] Within a set time window during which the reaction system is operating and the temperature is below the preset exothermic temperature, multiple torque data of the outer and inner stirrers are acquired according to a set acquisition cycle.

[0014] The acquired torque data of the outer and inner agitators are averaged to generate the outer reference torque and inner reference torque respectively.

[0015] Optionally, the steps for obtaining the heating rate and the normalized deviation coefficient include:

[0016] The differential of the real-time acquired center temperature is used as the heating rate;

[0017] When the heating rate is greater than the preset rate threshold within a set number of consecutive determination cycles, the real-time torque of the outer layer stirrer is divided by the outer layer reference torque, and then divided by the ratio of the real-time rotation speed of the outer layer stirrer to the corresponding reference rotation speed to obtain the outer layer torque ratio; and the real-time torque of the inner layer stirrer is divided by the inner layer reference torque, and then divided by the ratio of the real-time rotation speed of the inner layer stirrer to the corresponding reference rotation speed to obtain the inner layer torque ratio.

[0018] The normalized deviation coefficient is generated by subtracting the inner layer torque ratio from the outer layer torque ratio.

[0019] Optionally, reducing the speed of the inner agitator, increasing the speed of the outer agitator, and switching the coolant flowing into the jacket to a periodic on-off flow includes:

[0020] Reduce the rotation speed of the inner agitator according to the set decrease range;

[0021] The rotation speed of the outer agitator is increased synchronously according to a set rate of change in order to strip the reaction liquid from the inner wall area of ​​the reactor.

[0022] The coolant supplied to the jacket is switched on and off alternately according to a set time period to form the periodic opening and closing flow, which is synchronized with the increase in the rotation speed of the outer agitator.

[0023] Optionally, the pumping of a mixture containing a chain transfer agent and a terminator into the central region via the internal channel includes:

[0024] During the cycle of increasing the speed of the outer stirrer to perform stripping on the reaction solution, the instantaneous rate of change of the real-time torque of the inner stirrer is extracted;

[0025] When the real-time torque of the inner agitator is greater than the preset sudden change threshold and the instantaneous change rate is greater than the set change rate threshold, the temperature of the mixture is configured to be lower than the set temperature threshold and pumped into the central region through the internal channel.

[0026] The pumping cycle of the mixture overlaps with the cycle of the rotational speed increase of the outer agitator.

[0027] Optionally, the inner agitator is configured to have a liquid outlet communicating with the internal channel; the method further includes:

[0028] During pumping cycles other than those of the mixture, inert gas is introduced into the internal channel to set the gas pressure in the internal channel to be greater than a set gas pressure threshold, so as to block the reaction liquid from entering the internal channel through the liquid outlet.

[0029] When the mixture is triggered to be pumped into the central region through the outlet, the inert gas is stopped from being supplied to the internal channel.

[0030] Optionally, restoring the state before the speed adjustment includes:

[0031] When the heating rate is less than the set stable threshold and the normalized deviation coefficient is less than the preset decoupling threshold, the alternating on / off of the coolant flowing into the jacket is stopped.

[0032] The rotation speeds of the inner and outer agitators are restored to their original states before the speed adjustment.

[0033] Stop pumping the mixture in and resume the flow of the inert gas into the internal channel.

[0034] Optionally, the jacket can be configured to include multiple independent segmented jackets;

[0035] The alternating switching on and off of the coolant supplied to the jacket includes:

[0036] A set phase delay time is configured between adjacent segmented jackets;

[0037] According to the phase delay time, the switching on and off actions of each segment jacket on the coolant are triggered sequentially and in staggered order.

[0038] The adjacent segmented jackets are configured to maintain an asynchronous on / off state within the same set time period.

[0039] Optionally, the method further includes:

[0040] When the normalized deviation coefficient is less than the preset decoupling threshold, the flow rate of the coolant entering the jacket is adjusted based on the obtained center temperature.

[0041] When the coolant flowing into the jacket is switched to the periodic on-off flow, the adjustment of the coolant flow rate into the jacket based on the center temperature is stopped.

[0042] When the alternating on / off of the coolant supplied to the jacket is stopped, the regulation of the coolant flow rate supplied to the jacket based on the center temperature is resumed.

[0043] Secondly, this application provides a styrene-butadiene latex preparation system for artificial turf back coating, which adopts the following technical solution: a styrene-butadiene latex preparation system for artificial turf back coating, the system comprising:

[0044] A reaction vessel comprising a jacket, an outer agitator, and an inner agitator with internal channels, and a control unit communicatively connected to the jacket, the outer agitator, and the inner agitator, the control unit being configured to perform the following operations:

[0045] When the temperature of the reaction system is lower than the preset exothermic temperature, the torque of the outer and inner stirrers is collected to establish the outer reference torque and the inner reference torque.

[0046] When the temperature of the reaction system reaches the exothermic temperature, the center temperature of the central region of the reaction system, the near-wall temperature of the inner wall region of the reactor, and the real-time rotation speed and real-time torque of the outer and inner stirrers are obtained.

[0047] When the heating rate of the center temperature is greater than the preset rate threshold, and the temperature difference between the center temperature and the near-wall temperature is greater than the preset temperature difference threshold, and the normalized deviation coefficient determined by the real-time rotation speed, real-time torque and the corresponding reference rotation speed, reference torque is greater than the preset decoupling threshold, the rotation speed of the inner agitator is reduced, the rotation speed of the outer agitator is increased, and the coolant flowing into the jacket is switched to periodic opening and closing flow.

[0048] During the speed adjustment, if the real-time torque of the inner agitator is greater than the preset sudden change threshold, the mixture containing chain transfer agent and terminator is pumped into the central region through the internal channel.

[0049] When the heating rate and the normalized deviation coefficient fall back to the preset range, the state before the speed adjustment is restored.

[0050] In summary, this application includes the following beneficial technical effects:

[0051] 1. This application employs a multi-dimensional synergistic intervention strategy to precisely resolve the decoupling effect of heat and shear force during the peak of the exothermic polymerization reaction. This fundamentally suppresses the problem of widened latex particle size distribution caused by boundary layer microgelation, ensuring that styrene-butadiene latex has excellent backing penetration and leveling properties and grass fiber root adhesion, thus avoiding quality defects such as grass shedding during the use of artificial turf.

[0052] 2. By adopting a two-level nested judgment logic, and combining multiple parameters such as the central temperature rise rate, the temperature difference between the center and near the wall, and the normalized deviation coefficient, it can accurately capture the critical window of decoupling state. Compared with single parameter judgment, it significantly improves the accuracy and foresight of state recognition, and provides a reliable basis for subsequent collaborative intervention.

[0053] 3. By adjusting the stirring speed in the opposite direction, periodically opening and closing the pulsed coolant, and synergistically pumping in the chain transfer agent and terminator mixture, multi-dimensional control of heat source, flow field reconstruction, heat transfer enhancement, and reaction blocking is achieved. This effectively curbs the formation and development of local high-temperature hot spots, ensuring the stable and controllable polymerization reaction process and the high-quality stability of the finished latex. Attached Figure Description

[0054] Figure 1 This is a logical flowchart of the method in this application;

[0055] Figure 2 This is a cross-sectional view of the reactor structure and a schematic diagram of the multi-source sensor layout in this application;

[0056] Figure 3 This is a schematic diagram comparing the intervention actions and flow field effects of conventional processes and the present application in a decoupled state. Detailed Implementation

[0057] The following combination Figures 1-3 This application will be described in further detail.

[0058] The backcoating process for artificial turf places stringent requirements on the performance of styrene-butadiene latex, demanding an extremely narrow particle size distribution and very low gel content to ensure excellent penetration and leveling properties of the backing fabric and adhesion to the grass roots. In existing large-scale polymerization processes for styrene-butadiene latex, during the peak of the exothermic reaction, when the jacket is fully opened for cooling to suppress the central exothermic peak, the viscosity of the reaction liquid near the reactor wall increases sharply due to rapid cooling, forming a high-viscosity cold boundary layer. This boundary layer blocks the heat transfer path from the central high-temperature reaction liquid to the reactor wall. Simultaneously, it causes the shear force of conventional stirring to rapidly decrease when penetrating the boundary layer, forming localized high-temperature hot spots inside the boundary layer that cannot be effectively stirred. This leads to uncontrolled monomer polymerization, generating numerous microscopic gel clusters. These gel clusters result in a wider particle size distribution in the finished latex, forming a pseudo-skin during backcoating, hindering latex penetration, and ultimately causing quality problems such as reduced grass pull-out strength and easy grass shedding.

[0059] like Figure 1 As shown, this application discloses a method for preparing styrene-butadiene latex for artificial turf back coating. Based on a styrene-butadiene latex preparation system for artificial turf back coating, and addressing the core deficiencies of the prior art, this method resolves the heat-shear force decoupling effect during polymerization through complete closed-loop control logic and coordinated intervention actions, thereby fundamentally suppressing the occurrence of boundary layer microgelation. The following steps will be described in detail:

[0060] S1 polymerization reaction preparatory work and control parameter setting

[0061] This step lays the foundation for dedicated hardware, a stable reaction system, reliable equipment operation, and clear control judgment criteria for the closed-loop control of the entire process of styrene-butadiene latex polymerization reaction. It ensures that the status monitoring, logical judgment, and collaborative intervention actions of the subsequent reaction process can be executed stably and accurately, and fully supports the entire process handling logic of this solution for the heat-shear force decoupling effect.

[0062] Hardware configuration confirmed for the S11 polymerization-specific reaction system.

[0063] This step confirms that the configuration of the core container for the polymerization reaction and the supporting functional units are fully matched to the implementation requirements of the scheme, providing a dedicated physical carrier for state perception and collaborative control throughout the entire process.

[0064] A pressure-resistant stainless steel polymerization reactor is used as the core reaction vessel. The reactor's outer wall is jacketed, comprising three independent segmented jackets arranged axially from top to bottom, corresponding to the upper liquid level zone, the main reaction zone, and the bottom zone of the reaction liquid. Each segmented jacket's inlet is equipped with a high-frequency switching solenoid valve, allowing independent control of the coolant's on / off state and timing. The reactor contains two completely independently driven agitators. The first is an outer agitator with an anchor-type scraper structure, where the blades are flush against the inner wall of the reactor. It is powered by an independent variable frequency drive motor and equipped with a built-in torque acquisition module mounted on the drive shaft. This module collects dynamic torque data of the outer agitator in real time, with a acquisition frequency of at least 1Hz. The second is an inner agitator located in the central axis area of ​​the reactor. It employs a 3- to 5-stage turbine propeller structure, with the turbine propellers evenly distributed along the shaft axis. It is also powered by an independent variable frequency drive motor and equipped with a built-in torque acquisition module of the same specifications, allowing real-time collection of dynamic torque data of the inner agitator during operation. The inner agitator has a hollow shaft with a through-hole channel inside. Multiple liquid outlet holes with a diameter of 2mm to 5mm are opened on the side wall of the shaft and are connected to the internal channel. Two to four outlet holes are set at the corresponding positions of each turbine impeller along the shaft axis and are evenly radially opened along the circumference of the shaft. They radially penetrate the side wall of the shaft to connect the internal channel with the reaction system inside the vessel, which can realize the uniform diffusion of the reagent at the full depth in the central region.

[0065] A temperature acquisition unit is included, comprising multiple temperature probes inserted into the central region of the reaction system, and a near-wall temperature sensor array attached to the inner wall of the reactor. The multiple temperature probes are inserted to the designed liquid level depth within the reactor, with 3 to 5 measuring points arranged axially, covering the upper, middle, and lower regions of the reaction liquid, enabling comprehensive acquisition of temperature data from the central region of the reaction system. The near-wall temperature sensor array is arranged in 4 to 6 groups circumferentially along the inner wall of the reactor, with 3 measuring points in each group along the axial direction, corresponding to the coverage areas of the upper, middle, and lower jacket sections, respectively, enabling comprehensive acquisition of the near-wall temperature of the reactor's inner wall region.

[0066] like Figure 2 As shown, the reactor body has three independent cooling jackets arranged axially along its outer side: an upper section, a middle section, and a lower section. Inside the reactor, a multi-stage turbine agitator with an inner hollow shaft is positioned at the center, while an outer anchor-type scraper agitator is positioned close to the reactor wall. In the temperature measurement system, multiple temperature probes are vertically inserted into the central area of ​​the reactor, while an array of wall temperature sensors is attached to the circumferential and axial sides of the reactor's inner wall.

[0067] The system is equipped with a variable frequency drive unit, which is electrically connected to the drive motors of both the outer and inner agitators. This unit can receive control commands to independently adjust the operating speed of both agitators, with a speed adjustment accuracy of no less than 1 rpm. A coolant control unit is also included, connected to the high-frequency solenoid valves of each segment jacket. This unit can receive control commands to adjust the on / off state and timing of the coolant flow, with a solenoid valve response time of no more than 100ms. A reagent delivery unit is also included. Its storage tank can pre-cool and store the mixture, and its delivery outlet is connected to the internal channel of the inner agitator. This unit can receive control commands to precisely pump a preset flow rate of the mixture into the internal channel of the inner agitator, with precise pressure control to ensure smooth injection of the reagent into the reactor system. Finally, an inert gas supply unit is included. This unit uses a nitrogen cylinder with a pressure reducing and stabilizing valve. Its output port is connected to the internal channel of the inner agitator, allowing it to receive control commands to introduce high-purity nitrogen into the internal channel and precisely maintain stable gas pressure within the channel.

[0068] The system is equipped with a control unit, which establishes bidirectional communication connections with the temperature acquisition unit, frequency converter drive unit, torque acquisition module, coolant control unit, reagent delivery unit, and inert gas supply unit. It can complete the synchronous acquisition of multi-source data, real-time calculation of core parameters, nested judgment of logical states, and coordinated issuance of execution actions. The latency of the entire process data processing and command issuance does not exceed 200ms.

[0069] Functional verification and linkage debugging of S12 hardware system

[0070] After the hardware configuration is confirmed, this step completes the functional verification and linkage debugging of the entire system hardware to ensure the accuracy of subsequent data acquisition and the reliability of execution actions, and to avoid control failures caused by equipment malfunctions during the response process.

[0071] First, complete the functional verification of each individual component. Then, start the control unit to complete the power-on initialization of the entire system hardware, confirming that the communication connections between each acquisition unit, execution unit, and control unit are normal, with no communication interruptions or data transmission delays. Read the real-time temperature data from the center temperature probe and near-wall temperature sensor of the temperature acquisition unit. Perform temperature calibration under normal temperature conditions, confirming that the accuracy deviation of the temperature data does not exceed 0.2℃, with no temperature drift or data anomalies. Start the outer and inner agitators separately, and complete no-load operation tests at the preset reference speeds. Confirm that the frequency converter drive function of both agitators is normal, operating smoothly without jamming, and that the matching torque acquisition module can stably output real-time torque data, with the data acquisition frequency and accuracy meeting the preset requirements.

[0072] On / off commands were issued to the high-frequency solenoid valves of each segment jacket to confirm that the valves' response speed met the requirements, that they could accurately perform on / off control, and that there were no blockages or leaks in the coolant pipeline. Operating commands were then issued to the reagent delivery unit and the inert gas supply unit to confirm that the delivery pipelines were unobstructed, that the control accuracy of the reagent pump flow rate and nitrogen gas pressure met the preset requirements, that the pipeline switching action was timely, and that there were no cross-circuiting or leaks.

[0073] After the individual component verification is completed, the entire system is debugged in a coordinated manner. The simulation of possible speed adjustment, coolant on / off switching, and nitrogen and reagent delivery switching actions during the reaction process is carried out to confirm that each execution unit can synchronously receive control commands and complete the corresponding actions without action conflicts or timing deviations, thus providing reliable hardware operation guarantee for the full process control of the subsequent polymerization reaction.

[0074] Preparation and System Construction of S13 Polymerization Reactants

[0075] After the hardware system verification and debugging are completed and all equipment is confirmed to be operating normally, this step completes the precise configuration and addition of polymerization reaction materials, and builds a stable and compliant polymerization reaction system.

[0076] According to the polymerization formula of styrene-butadiene latex for artificial turf backing, the precise weighing and preparation of various reactive materials were completed. The polymer material includes main monomers, functional monomers, emulsion system, initiation system, and deionized water medium. Based on a total mass of 100 parts of the reaction system, the dosage range of each component is as follows: 35-50 parts of main monomers, of which the main monomers are butadiene and styrene, with a mass ratio of 30:70 to 50:50; 1-5 parts of functional monomers, of which are unsaturated carboxylic acid monomers, including one or more of acrylic acid, methacrylic acid, and itaconic acid, used to adjust the adhesive properties and storage stability of the latex; 1-3 parts of the emulsion system, using environmentally friendly anionic emulsifiers, including one or more of sodium dodecylbenzenesulfonate and potassium disproportionated rosinate soap; 0.1-0.5 parts of the initiation system, using thermally decomposable aqueous initiators, including one or more of potassium persulfate and ammonium persulfate; the remainder is deionized water medium.

[0077] After the materials are prepared, deionized water, emulsifier, and water-soluble functional monomers are sequentially added to the reactor. The inlet and outlet of the reactor are sealed, and the air inside the reactor is replaced by purging with high-purity nitrogen after vacuuming. This replacement operation is repeated 2 to 3 times to ensure that the oxygen content inside the reactor is below 100 ppm. After replacement, the oil-soluble main monomers butadiene and styrene are added to the reactor. The outer and inner agitators are turned on, and the stirring is carried out at the preset reference speed of S14 for 30-60 minutes to ensure that the materials are fully mixed and emulsified, thus completing the construction of the polymerization reaction system. Simultaneously, a mixture containing chain transfer agent and terminator is pre-prepared in the storage tank of the reagent delivery unit. The mixture uses an aqueous dispersion of tert-dodecyl mercaptan and hydroquinone in a mass ratio of 3:1, and the total solid content of the mixture is controlled at 10-15%. The mixture is pre-cooled to below 5°C for later use.

[0078] After the system construction is completed, the control unit initiates the preheating program, heating the reaction system uniformly to 55-60℃ at a heating rate of 0.5-1℃ / min. After holding at this temperature for 10-20 minutes, the initiator aqueous solution, pre-prepared with deionized water, is added into the reactor in one go. The concentration of the initiator aqueous solution is controlled at 5-10%, initiating the free radical polymerization reaction. Simultaneously, during the non-mixed liquid pumping cycle of the entire polymerization reaction process, the control unit continuously controls the inert gas supply unit to introduce high-purity nitrogen into the internal channel of the inner stirrer, maintaining the gas pressure in the internal channel stable above the set gas pressure threshold, thus achieving full-process anti-clogging protection of the internal channel.

[0079] S14 core control threshold preset and fixed

[0080] After the reaction system is constructed, this step completes the preset of the core thresholds and parameters required for the whole process control of the polymerization reaction, providing a unified and clear benchmark for subsequent state judgment and action execution. All parameters are set based on the reaction mechanism of styrene-butadiene latex free radical polymerization and engineering practice experience of large-scale production, taking into account the sensitivity, anti-interference and process safety of control.

[0081] All thresholds and parameters are pre-stored and fixed in the control unit. The specific settings and basis for each parameter are as follows.

[0082] The preset exothermic temperature is set to 65℃. In the free radical polymerization reaction of styrene-butadiene latex, the self-accelerating effect and concentrated exothermic peak are concentrated in the range of monomer conversion rate of 30% to 70%. The control target temperature for conventional isothermal polymerization is 75℃ to 85℃. 65℃ is lower than the conventional isothermal control target and is in the critical range before the self-accelerating effect starts. At this temperature, the system reaction is stable, the material viscosity is uniform and stable, there is no risk of local heat accumulation, and a stable system environment can be provided for the acquisition of the reference torque.

[0083] The time window is set to 10 minutes, and the acquisition cycle is set to 1 second. The 10-minute time window allows for the acquisition of a sufficient amount of effective torque data, eliminating numerical errors caused by instantaneous fluctuations in equipment operation and localized material turbulence. The 1-second acquisition cycle ensures the density of the acquired data, improving the accuracy and representativeness of subsequent baseline torque calculations, and matching the minimum acquisition frequency of the torque acquisition module.

[0084] The preset rate threshold is set to 1.5℃ / min. During the stable operation phase of the polymerization reaction, the system's heating rate is typically below 0.5℃ / min. When the heating rate reaches 1.5℃ / min, it indicates that significant heat accumulation has occurred in the central region of the system, the self-accelerating effect of the polymerization reaction has been initiated, and the exothermic rate has exceeded the basic heat exchange capacity of a conventional cooling system. This threshold can accurately identify the critical state when the system enters the peak exothermic period, while effectively avoiding false triggering caused by instantaneous fluctuations in temperature acquisition.

[0085] The number of judgment cycles is set to 3, the duration of each judgment cycle is set to 2 seconds, and each judgment cycle covers 2 consecutive acquisition cycles. Using continuous exceedance of the standard for 3 consecutive judgment cycles as the trigger condition can effectively eliminate instantaneous noise in temperature acquisition and numerical fluctuations caused by local turbulence in the system, avoid erroneous triggering of subsequent in-depth judgment processes, and ensure that the judgment results can truly reflect the thermal accumulation trend of the system.

[0086] The preset temperature difference threshold is set to 4℃. Under stable reaction conditions, the temperature difference between the central region and the near-wall region of the reaction system is usually less than 1℃. When the temperature difference reaches 4℃, it indicates that a significant temperature gradient has formed between the materials in the near-wall region and the central region. The cooling effect in the near-wall region cannot be effectively transferred to the central region, and the heat transfer path of the system shows signs of obstruction. This threshold can be corroborated by the heating rate index to confirm the authenticity of the system's thermal accumulation state.

[0087] The preset decoupling threshold is set to 0.15. The normalized deviation coefficient is used to characterize the difference in the relative changes in resistance experienced by the outer and inner agitators. When the value is positive, it indicates that the increase in viscosity of the material near the wall is greater than that in the central region. When the value reaches 0.15, it indicates that a significant high-viscosity cold boundary layer has formed in the near-wall region, and the heat-shear force decoupling effect has emerged. If not intervened in time, it will quickly develop into heat transfer blockage and local hot spots, thereby triggering micro-gelation. This threshold setting can avoid frequent system malfunctions caused by an excessively low threshold, ensuring stable reaction operation, and can also avoid intervention lag caused by an excessively high threshold, missing the optimal window for handling the decoupling state.

[0088] The reduction rate is set to 50% of the inner layer's reference speed. This reduction rate can lower the inner layer agitator speed and reduce frictional heat generated by high-speed shearing in the central region while maintaining basic material flow in the central region. This avoids problems such as material stagnation and local reaction runaway caused by complete shutdown, thus reducing the heat load in the central region from the source. The reference speed of the inner layer agitator is preset to 60-100 rpm, and the reference speed of the outer layer agitator is preset to 20-40 rpm. This speed range matches the conventional mixing requirements of the styrene-butadiene latex polymerization system, ensuring the basic requirements of emulsification, mass transfer, and heat transfer of the system. It is also the fixed operating speed during the S2 reference torque acquisition stage.

[0089] The speed increase is set at 180% of the outer layer's base speed, meaning the target speed of the outer agitator after the increase is 1.8 times the base speed. This increase allows the outer agitator to generate strong shear force, effectively stripping away the high-viscosity cold boundary layer that has formed near the wall, breaking down the physical barrier that blocks heat transfer, and achieving forced convection displacement between the high-temperature material in the center and the low-temperature material near the wall. Simultaneously, it avoids problems such as excessive equipment load or excessive shearing of the system due to excessive speed increase. During the speed increase process, the control unit is configured with a speed change rate of 5-10 rpm / s to avoid equipment shock and drastic fluctuations in the system flow field caused by sudden speed changes.

[0090] The time cycle is set to 10 seconds, with the coolant on for 4 seconds and off for 6 seconds. This periodic on / off parameter creates a periodic water hammer effect and strong turbulence inside the jacket, breaking up the laminar heat transfer layer on the inner wall of the jacket and significantly improving the convective heat transfer coefficient on the jacket side. Simultaneously, the intermittent cooling method avoids excessive rapid cooling of the near-wall material caused by continuous coolant flow, preventing further thickening of the high-viscosity boundary layer, thus balancing cooling efficiency and boundary layer control.

[0091] The phase delay time is set to 3 seconds. The 3-second phase delay is one-third of the set time period, which allows the coolant on / off states of the upper, middle, and lower jackets to be staggered sequentially, forming an alternating cooling intensity distribution in the axial direction of the reactor. Combined with the rotational shearing action of the outer agitator, this breaks the uniform distribution of the axial boundary layer inside the reactor, avoids synchronous thickening of the boundary layer on the entire reactor wall, eliminates local heat transfer dead zones in the axial direction, and improves the heat transfer uniformity throughout the entire reactor.

[0092] The preset mutation threshold is set to 200% of the inner layer reference torque. The torque of the inner layer agitator is directly related to the viscosity of the material in the central region. During the stable operation phase of the reaction, the torque fluctuation range usually does not exceed 20% of the reference torque. When the torque reaches 200% of the reference torque, it indicates a sharp increase in the viscosity of the material in the central region, which is a key precursor to the concentrated polymerization reaction of monomers and the initiation of micro-explosive polymerization. This threshold can accurately identify the risk of reaction runaway in the central region.

[0093] The threshold for the rate of change is set to 50% / s. This value characterizes the instantaneous rate of change of the real-time torque of the inner agitator. When the rate of change reaches 50% / s, it indicates that the viscosity in the central region is rising very rapidly, and the polymerization reaction is in a critical state of being out of control. This can be distinguished from the slow viscosity increase during the normal polymerization process of the system, accurately identifying the precursor signal of micro-explosive polymerization and avoiding accidental triggering of the reagent pumping action.

[0094] The set temperature threshold for the mixture is 5℃. Pre-cooling the mixture to 5℃ allows for rapid temperature reduction in the localized high-temperature region upon injection, inhibiting further development of the self-accelerating reaction. Simultaneously, in conjunction with the chemical action of the reagents, it inhibits micro-agglomeration from both physical and chemical perspectives. This temperature ensures sufficient cooling without reducing the mixture's fluidity, thus preventing disruption to pumping and dispersion efficiency due to excessively low temperatures.

[0095] The gas pressure threshold is set to 0.15 MPa. During the polymerization reaction, the system pressure inside the reactor is usually between 0.1 MPa and 0.12 MPa. The internal channel gas pressure of 0.15 MPa is always higher than the system pressure inside the reactor, which can effectively block the reaction liquid from entering the internal channel through the liquid outlet, avoid the reaction liquid from undergoing polymerization reaction in the channel and causing blockage of the liquid outlet, and ensure the long-term unobstructed flow of the internal channel.

[0096] The stability threshold was set at 0.2℃ / min. This value indicates that the exothermic reaction at the center of the system has been effectively controlled, the polymerization reaction has returned to a stable operating stage, there is no risk of continuous heat accumulation, and the decrease in the normalized deviation coefficient confirms that the decoupling state of the system has been completely eliminated.

[0097] The control unit stores all the preset thresholds and parameters as a unified benchmark for data acquisition, parameter calculation, logic judgment, and action execution throughout the entire polymerization process, ensuring the consistency and stability of the control logic. Simultaneously, the control unit presets PID control loop parameters for coolant flow based on the center temperature. This ensures that during the normalized deviation coefficient is less than the preset decoupling threshold in the normal steady-state phase, the control unit continuously adjusts the coolant flow into the jacket based on the real-time collected center temperature through the PID control loop to maintain the isothermal control target for the polymerization reaction.

[0098] Establishment of S2 steady-state reference torque

[0099] This step follows up on the work completed in S1, including the construction of the polymerization reaction system, hardware system verification and debugging, and the solidification of core control thresholds. It establishes a precise torque benchmark for determining the state in the subsequent reaction process, eliminates numerical errors caused by differences in equipment structure and the initial state of materials, and serves as the core data foundation for subsequent heat-shear force decoupling state identification.

[0100] Confirmation of S21 reference acquisition trigger conditions

[0101] After the polymerization reaction starts, the system temperature gradually increases with the preheating program and the progress of the initial polymerization reaction. The control unit continuously monitors the overall temperature of the reaction system in real time, and simultaneously monitors the stability of the reaction. When the control unit confirms that the system temperature is consistently and stably lower than the preset exothermic temperature for curing in S1, and the stable state lasts for at least 5 minutes with temperature fluctuations not exceeding ±0.5℃, and the system is in a stable reaction state without drastic temperature rise, significant exothermic fluctuations, or uniform material mixing and emulsification, the triggering conditions for baseline torque acquisition are confirmed to be met. The preset exothermic temperature is 65℃, which is in the critical range before the self-acceleration effect of the polymerization reaction starts. At this stage, the system is in a homogeneous steady state, the material viscosity is uniform and stable, and there is no risk of local heat accumulation. The acquired torque data can accurately reflect the steady-state operating resistance benchmark of the two agitators in the normal reaction system, thus avoiding deviations in subsequent state judgments due to distorted benchmark data.

[0102] Continuous acquisition of S22 torque data

[0103] After confirming the trigger conditions for baseline data acquisition, the control unit calls the preset time window and acquisition cycle in S1. Within the 10-minute time window, it continuously acquires the operating torque data of the outer and inner agitators at a 1-second acquisition cycle. During the acquisition cycle, both the outer and inner agitators maintain stable operation at the preset baseline speed in S1, without performing any speed adjustment actions, ensuring the consistency of the acquired data. The control unit synchronously timestamps each set of acquired torque data to ensure that the torque data of the outer and inner agitators are completely synchronized in the time dimension, avoiding timing deviations in subsequent data processing. The 10-minute time window can acquire sufficient effective data, eliminating numerical errors caused by instantaneous fluctuations in equipment operation and local turbulence of materials. The 1-second acquisition cycle ensures data acquisition density and maintains consistency with the real-time data acquisition frequency during the subsequent exothermic period, providing a sufficient, reliable, and dimensionally consistent data source for subsequent baseline torque calculation.

[0104] S23 reference torque generation and solidification

[0105] After completing torque data acquisition within the set time window, the control unit averages the acquired torque data from multiple sets of the outer agitator to generate the outer reference torque. Similarly, it averages the acquired torque data from multiple sets of the inner agitator to generate the inner reference torque. The averaging process uses an arithmetic mean calculation method. Before calculation, instantaneous outliers exceeding three times the standard deviation are removed, and then the valid data are arithmetically averaged. This effectively filters abnormal fluctuations in the torque data and eliminates the influence of structural differences between the two agitators and differences in the initial viscosity of the materials on the absolute torque value. This ensures that the subsequently calculated torque variation parameters accurately reflect the relative viscosity changes in different regions of the system, rather than absolute differences caused by the equipment itself. The control unit stores the generated outer and inner reference torques as fixed benchmarks for torque deviation calculation and normalized deviation coefficient generation throughout the entire polymerization process, ensuring the consistency and stability of the entire process state determination logic.

[0106] Real-time monitoring and nested determination of the reaction state during the S3 exothermic period

[0107] This step follows up on the solidification of the outer and inner reference torques completed in S2. After the polymerization reaction enters the exothermic critical stage, it completes the synchronous acquisition of the entire process status data, the real-time calculation of the core judgment parameters, and the nested precise judgment of the decoupled state.

[0108] S31 Multi-dimensional Real-time Data Synchronous Acquisition

[0109] When the control unit detects that the temperature of the reaction system reaches the preset exothermic temperature for curing in S1, it immediately initiates the full-process real-time monitoring process for the exothermic period. The preset exothermic temperature is 65℃, which is the critical node for the initiation of the self-accelerating effect of styrene-butadiene latex free radical polymerization. From this point onward, the system enters a reaction stage with concentrated exothermic risks, requiring high-frequency, multi-dimensional status monitoring. The control unit calls upon a 1-second acquisition cycle identical to that of S22 to simultaneously collect four types of core operating data. The first type is the center temperature of the central region of the reaction system, acquired through multi-point temperature probes configured in S1. The arithmetic mean of all central temperature measurement points is taken as the final center temperature, covering the temperature information of the central region at the full depth of the reaction liquid, truly reflecting the exothermic state of the system's core. The second type is the near-wall temperature of the inner wall region of the reactor, acquired through a near-wall temperature sensor array configured in S1. The arithmetic mean of all near-wall temperature measurement points is taken as the final near-wall temperature, comprehensively acquiring the material temperature distribution near the reactor wall, reflecting the cooling state and material characteristic changes in the near-wall region. The third category is the real-time torque and speed of the outer agitator, acquired through a torque acquisition module and frequency converter, directly reflecting the flow resistance and viscosity changes of the material near the wall. The fourth category is the real-time torque and speed of the inner agitator, acquired through a torque acquisition module and frequency converter, directly reflecting the flow resistance and viscosity changes of the material in the central region. The control unit marks each set of synchronously acquired data with a unified timestamp, ensuring that temperature, torque, and speed data are completely aligned in time, avoiding errors in subsequent parameter calculations due to timing discrepancies, and providing a foundation for the accurate calculation of core judgment parameters.

[0110] Real-time calculation of S32 core decision parameters

[0111] Based on synchronously acquired multi-dimensional real-time data, the control unit calculates the heating rate, a core judgment parameter, in real time. The heating rate is calculated by taking the derivative of the real-time acquired center temperature with respect to time. In continuous acquisition scenarios in industrial settings, this derivative calculation is achieved by dividing the center temperature difference between two adjacent acquisition cycles by the duration of the acquisition cycle. The result is then converted into a value in °C / min, directly reflecting the instantaneous temperature change trend in the central region. This provides extremely high real-time performance and enables rapid capture of the initiation signal of system heat accumulation.

[0112] S33 Two-level nested state determination

[0113] The control unit executes a two-level nested decision logic. First, it completes the first-level thermal accumulation trend determination. Only when the first-level determination conditions are fully met is the second-level decoupled state comprehensive determination process activated. This nested logic reduces the system's invalid continuous calculations and significantly improves the anti-interference and accuracy of the determination results through multi-dimensional progressive verification, avoiding false triggers caused by fluctuations in a single parameter. This differs from the simple threshold determination of a single parameter in existing technologies.

[0114] S331 First-level thermal accumulation trend determination

[0115] The control unit continuously judges the real-time calculated heating rate and verifies the state of continuous exceeding the heating rate limit. The control unit calls the set number of judgment cycles and preset rate thresholds fixed in S1, where the set number of judgment cycles is 3, the duration of each judgment cycle is 2 seconds, and the preset rate threshold is 1.5℃ / min. When the average heating rate corresponding to each of the 3 consecutive judgment cycles is greater than 1.5℃ / min, the control unit completes the first-level judgment, confirming that the system has shown a clear and continuous trend of heat accumulation, and then activates the second-level judgment process.

[0116] Using continuous exceedances over multiple consecutive cycles as the triggering condition can effectively filter out instantaneous noise and numerical fluctuations caused by local turbulence in the temperature acquisition process, avoid triggering subsequent in-depth judgments due to single-point data anomalies, and ensure that the judgment results can truly reflect the overall thermal accumulation state of the system.

[0117] S332 Second-Level Decoupling State Comprehensive Judgment

[0118] After the second-level judgment process is activated, the control unit immediately calculates the normalized deviation coefficient based on the synchronously collected real-time speed and torque data. This calculation is only initiated after the first-level heat accumulation judgment is passed, to avoid invalid calculations and logical contradictions.

[0119] The first step involves the control unit dividing the real-time torque of the outer agitator by the outer reference torque solidified in S2, and then dividing this by the ratio of the real-time rotational speed of the outer agitator to the corresponding reference rotational speed, to obtain the outer torque ratio. This ratio not only eliminates the influence of the absolute value of the initial torque of the outer agitator and differences in equipment structure, but also eliminates the physical bias amplification effect of sudden changes in mechanical speed on torque during rotational speed coordination through a speed compensation mechanism. This allows it to independently and accurately reflect the relative change in the apparent viscosity of the material in the near-wall region.

[0120] The second step involves the control unit dividing the real-time torque of the inner agitator by the inner layer reference torque solidified in S2, and then dividing by the ratio of the real-time rotational speed of the inner layer agitator to the corresponding reference rotational speed, to obtain the inner layer torque ratio. Similarly, this compensation eliminates the torque reduction interference caused by the inner layer speed reduction, and can directly and accurately reflect the relative change in the viscosity of the material in the central region.

[0121] The third step involves the control unit subtracting the inner layer torque ratio from the outer layer torque ratio to generate a normalized deviation coefficient. This coefficient is a dimensionless parameter that completely solves the core problem of the incomparability of absolute torque values ​​between the inner and outer agitators due to their different structural forms and dynamic changes in rotational speed during operation. It can directly quantify the relative changes in the actual viscosity of the material in the near-wall region and the central region, accurately reflecting the degree of formation of the high-viscosity cold boundary layer and the decoupling state of the flow field. This is the core innovative parameter of this solution for breaking the physical closed-loop deadlock and identifying the decoupling effect.

[0122] After calculating the normalized deviation coefficient, the control unit continuously verifies two core indicators: the real-time temperature difference between the center temperature and the near-wall temperature, and the synchronously calculated normalized deviation coefficient. The control unit calls the preset temperature difference threshold and preset decoupling threshold fixed in S1, where the preset temperature difference threshold is 4℃ and the preset decoupling threshold is 0.15. When the real-time temperature difference between the center temperature and the near-wall temperature is consistently greater than 4℃, and the normalized deviation coefficient calculated from the synchronously collected data is consistently greater than 0.15, the control unit completes the second-level judgment. Combining this with the result of the first-level judgment indicating that the heating rate exceeds the limit, it confirms that all three triggering conditions are met, and the heat-shear force decoupling state within the system is formally established. The persistently excessive real-time temperature difference verifies the existence of a significant spatial temperature gradient within the system, indicating that heat from near-wall cooling cannot be effectively transferred to the central region, and the heat transfer path shows clear signs of obstruction. The persistently excessive normalized deviation coefficient verifies that the increase in the actual viscosity of the material near the wall region significantly exceeds that in the central region, indicating the formation of a stable, highly viscous, cold boundary layer near the wall, and the decoupling of the flow field and heat transfer state between the inner and outer regions. The simultaneous verification of these two indicators, combining the thermodynamic and hydrodynamic states of the system, achieves multi-dimensional cross-verification of the decoupling phenomenon. Compared to existing technologies that rely solely on temperature or viscosity, this approach can more accurately and earlier identify the critical state of microscopic gelation, providing a reliable basis for subsequent coordinated intervention actions.

[0123] S4 Decoupling State Multidimensional Collaborative Intervention Control

[0124] This step follows the final determination of the heat-shear force decoupling state completed in S3. After the control unit confirms that the decoupling state has been formally established, multi-dimensional collaborative intervention actions are executed simultaneously. Efforts are made simultaneously from multiple dimensions such as flow field reconstruction, heat transfer enhancement, and source heat control to accurately resolve the decoupling effect that has appeared and curb the development trend of boundary layer micro-gelation from the root.

[0125] S41 conventional temperature control circuit termination

[0126] After the control unit completes the final determination of the decoupling state, it immediately issues a control command to terminate the PID control loop for coolant flow based on the center temperature during normal operation. Simultaneously, it completely transfers control of the jacket coolant to the periodic on / off and asynchronous on / off control logic, avoiding command conflicts caused by multiple control logics operating in parallel. The conventional PID control loop uses the deviation between the center temperature and the set target temperature as its core adjustment basis, continuously increasing the coolant flow rate when the center temperature exceeds the target. However, in the decoupling state, a continuously high coolant flow rate further exacerbates the rapid cooling effect in the near-wall region, driving the continuous thickening of the high-viscosity cold boundary layer, which in turn exacerbates the core problem of heat transfer path obstruction. Terminating this conventional loop fundamentally avoids the inherent conflicts in the control logic, providing the execution conditions for subsequent pulsed cooling control and ensuring the coordinated consistency of intervention actions throughout the entire process.

[0127] S42 stirring speed reverse coordinated adjustment

[0128] Completely synchronized with the shutdown action of the conventional temperature control circuit, the control unit sends commands to the frequency conversion drive units of the outer and inner agitators to execute the reverse coordinated adjustment of the speed of the two agitators. The speed adjustment actions of the two agitators start and take effect simultaneously, realizing the rapid reconstruction of the flow field state inside the vessel.

[0129] S421 Inner Layer Agitator Speed ​​Adjustment

[0130] The control unit calls the preset reduction range in S1 and adjusts the operating speed of the inner agitator downwards. The reduction range is set to 50% of the inner agitator's base speed, meaning the adjusted speed of the inner agitator is 50% of the base speed. The inner agitator's operating area is concentrated in the central region of the reaction system. Reducing its operating speed directly reduces frictional heat generated by high-speed shear in the central region, lowering the heat load on the central hot spot area from the source and preventing the temperature in the central region from continuously rising. At the same time, the 50% reduction range can maintain the basic material flow state in the central region while reducing shear heat generation, avoiding the problem of central material stagnation and further loss of control of the local polymerization reaction caused by complete shutdown.

[0131] S422 outer agitator speed adjustment

[0132] Completely synchronized with the action of reducing the rotational speed of the inner stirrer, the control unit calls the set lifting amplitude固化 in S1 and raises the operating rotational speed of the outer stirrer upward, increasing the rotational speed of the outer stirrer to 180% of the reference rotational speed. The outer stirrer adopts an anchor-type scraping wall structure that closely adheres to the kettle wall. After increasing its operating rotational speed, strong rigid shear force can be generated, directly stripping the reaction liquid in the inner wall area of the reactor, breaking up the highly viscous cold boundary layer that has formed in the near-wall area, breaking the physical barrier of heat transfer blockage, promoting the forced convection replacement of the central high-temperature material and the near-wall low-temperature material, and completely opening up the heat transfer path inside the kettle. This action forms an accurate cooperation with the speed reduction action of the inner stirrer, simultaneously exerting force from two dimensions of heat source control and heat transfer obstacle removal, and quickly遏制 the continuous deterioration of the decoupled state.

[0133] S43 Periodic opening and closing control of the jacket coolant

[0134] Completely synchronized with the action of reverse adjustment of the stirring rotational speed, the control unit issues an instruction to the coolant control unit supporting the jacket, switching the coolant flowing into the jacket from the conventional continuous flowing-in mode to the periodic opening and closing flowing mode. The control unit calls the set time period固化 in S1, and the set time period is 10s, where the coolant connection duration is 4s and the disconnection duration is 6s. The periodically opening and closing coolant flow can form a periodic water hammer effect and strong turbulence inside the jacket, shattering the laminar heat transfer bottom layer on the inner wall of the jacket and significantly increasing the convective heat transfer coefficient on the jacket side; at the same time, the intermittent cooling method can avoid the excessive sudden cooling of the near-wall material caused by continuous flowing-in of the coolant and prevent the further thickening of the highly viscous cold boundary layer. This action is executed synchronously with the boundary layer stripping action of the outer stirrer. The convective heat transfer path of the material is opened up inside the kettle, and the heat transfer efficiency on the cooling side is simultaneously enhanced outside the kettle. The two cooperate with each other to achieve the synchronous improvement of the heat transfer efficiency inside and outside the kettle and quickly导出 the heat accumulated in the central area.

[0135] S44 Asynchronous on-off control of the segmented jacket

[0136] During the execution of the periodic opening and closing control of the coolant, the control unit performs asynchronous on-off control on multiple independent segmented jackets supporting the reactor.

[0137] S441 Invocation of the phase delay parameter

[0138] The control unit calls the phase delay time固化 in S1, and the phase delay time is set to 3s. Between adjacent segmented jackets, the on-off actions of the coolant are staggered in sequence according to this phase delay time. The 3s phase delay is one-third of the set time period, which can make the on-off states of the upper, middle, and lower three segmented jackets form a uniform time sequence misalignment, avoiding the problem of synchronous thickening of the boundary layer caused by synchronous cooling of the entire kettle wall surface.

[0139] S442 Execution of the asynchronous on-off action

[0140] The control unit triggers the coolant on / off actions of each segment jacket sequentially from top to bottom according to a preset phase delay time, ensuring that adjacent segment jackets maintain an asynchronous on / off state within the same set time period. Specifically, the upper segment jacket is triggered to connect at 0s and disconnect at 4s; the middle segment jacket is triggered to connect at 3s and disconnect at 7s; and the lower segment jacket is triggered to connect at 6s and disconnect at 10s. This timing control method creates an alternating cooling intensity distribution along the axial direction of the reactor. Combined with the rotational shearing action of the outer agitator, it further breaks the uniform distribution of the axial boundary layer within the reactor, eliminates localized heat transfer dead zones, improves heat transfer uniformity across the entire reactor, and prevents the continued development of localized decoupling.

[0141] Combination Figure 3 As shown, when the decoupling state is triggered, the conventional process (comparative example) maintains the reference speed of the inner and outer agitators unchanged, and the cooling flow rate of the three-section jacket is constant, resulting in a high-viscosity flow field in the reactor that is prone to forming a crust. However, the embodiment of this application (the process of this invention) performs spatiotemporal coordinated intervention: the speed of the inner agitator is reduced to 50% of the reference speed, and the speed of the outer agitator is increased to 180% of the reference speed; at the same time, the upper, middle and lower cooling jackets enter a periodic opening and closing mode, and the actions of each section are phase-delayed and staggered. Figure 3 By using comparative diagrams, the abstract concept of time-series control and physical fluid changes are visualized, intuitively demonstrating how this scheme breaks the traditional global uniform flow field and reconstructs a complex and interwoven flow and temperature field through "outer layer strong shear acceleration + inner layer deceleration and heat reduction" and "asynchronous pulse cooling". This proves that the method steps of this application have a substantial and predictable effect on breaking up the high-viscosity cold boundary layer.

[0142] Targeted emergency response to the risk of explosive clustering at the S5 center

[0143] This step closely follows the decoupled state multidimensional collaborative intervention process initiated by S4. Throughout the entire execution cycle of the collaborative intervention action, it conducts real-time monitoring, dual-dimensional risk assessment, and precise targeted emergency response for the micro-explosive polymerization risk most likely to occur in the central area of ​​the polymerization reaction. It directly blocks the locally runaway polymerization reaction from the perspective of chemical regulation, and avoids the formation of micro-gel clusters from the source.

[0144] Real-time monitoring of the torque of the S51 inner agitator

[0145] During the entire execution of the S4 collaborative intervention action, specifically the cycle in which the outer agitator speed is increased to strip the reaction liquid, the control unit continuously calls the 1-second acquisition cycle, identical to the previous process, to continuously acquire real-time torque data from the inner agitator and simultaneously calculate the instantaneous rate of change of real-time torque. The instantaneous rate of change is calculated by dividing the torque difference between two adjacent acquisition cycles by the duration of the acquisition cycle, and then converted into a relative rate of change in % / s. This allows for real-time, highly sensitive reflection of the viscosity change rate of the material in the central region, accurately capturing early warning signals of uncontrolled polymerization. The inner agitator's operating area completely covers the central hotspot-prone area of ​​the reaction system. Its operating torque is directly positively correlated with the viscosity of the material in the central region, allowing it to provide feedback on the intensity of the polymerization reaction in the central region earlier than temperature signals, providing the most direct and fastest-responding core data support for subsequent risk assessment.

[0146] Triggering criteria for S52 explosive polymerization risk

[0147] The control unit performs a synchronous dual-index closed-loop judgment based on the real-time acquired torque of the inner agitator and the synchronously calculated instantaneous rate of change. The control unit calls the preset mutation threshold and the set rate of change threshold fixed in S1, where the preset mutation threshold is 200% of the inner layer reference torque and the set rate of change threshold is 50% / s. During the stable operation phase of the polymerization reaction, the fluctuation range of the inner agitator torque typically does not exceed 20% of the inner layer reference torque. The 200% mutation threshold clearly distinguishes between the slow viscosity increase caused by normal polymerization and the abnormally rapid increase in viscosity caused by reaction runaway, accurately identifying the core precursor to micro-explosive polymerization. The 50% / s rate of change threshold effectively filters out small torque fluctuations caused by normal temperature rise and material flow, avoiding false triggering of emergency actions. When the real-time torque of the inner agitator continuously exceeds the preset mutation threshold, and the synchronously calculated instantaneous rate of change continuously exceeds the set rate of change threshold, the control unit determines that there is a clear risk of micro-explosive polymerization in the central region of the reaction system and immediately triggers the targeted reagent pumping action.

[0148] S53 Mixture Targeted Pumping Control

[0149] Upon triggering the targeted agent pumping action, the control unit immediately sends a command to the inert gas supply unit to stop the supply of inert gas to the internal channels of the inner stirrer; simultaneously, it sends a precise pumping command to the agent delivery unit, pumping the pre-cooled mixture below the set temperature threshold directly and uniformly into the central runaway region of the reaction system through the internal channels of the inner stirrer and the liquid outlet on the side wall of the rotating shaft. The control unit calls upon the set temperature threshold of the solidified mixture in S1, which is set to 5°C. The mixture pre-cooled to below 5°C, when injected into the central region, can rapidly reduce the temperature of the local hot spot, physically inhibiting the further development of the self-accelerating reaction. The mixture uses an aqueous dispersion of chain transfer agent tert-dodecyl mercaptan and terminator hydroquinone in a mass ratio of 3:1. The chain transfer agent can rapidly regulate the growth process of polymer molecular chains and block the cross-linking reaction between molecular chains, while the terminator can efficiently capture the active free radicals of the polymerization reaction and directly terminate the runaway chain polymerization reaction. The two work together to achieve dual regulation from physical cooling to chemical blocking, and act directly on the core area of ​​the runaway reaction without interfering with the normal polymerization reaction in other areas of the reactor.

[0150] The mixture is injected using a single, metered pumping method, with a single pumping volume of 0.1-0.3% of the total mass of the reaction system. The pumping time is controlled within 5-10 seconds, and the pumping pressure is controlled to be 0.05-0.1 MPa higher than the pressure of the system inside the reactor, ensuring that the mixture can be smoothly sprayed into the central area through the outlet. The pumping cycle of the mixture completely overlaps with the rotation speed increase cycle of the outer agitator, ensuring that the reagent is fully dispersed in the central area after injection and is not quickly carried to the near-wall area, maximizing the emergency control effect of the reagent. After the pumping action is completed, the control unit continuously monitors the torque status of the inner agitator. If the torque and instantaneous change rate continue to exceed the limit, a supplementary pumping action can be triggered again after an interval of 30 seconds, with the supplementary pumping volume not exceeding 50% of the initial pumping volume.

[0151] S54 internal channel anti-blockage protection

[0152] Throughout the entire process cycle without mixed liquid pumping, including the heating phase, steady-state reaction phase, and synergistic intervention phase of the polymerization reaction when pumping is not triggered, the control unit continuously controls the inert gas supply unit to introduce high-purity nitrogen into the internal channel of the inner agitator. This ensures that the gas pressure within the internal channel is stably maintained above the set gas pressure threshold for solidification in S1. The set gas pressure threshold is 0.15 MPa. During the entire polymerization process, the system pressure inside the reactor is typically maintained stably between 0.1 MPa and 0.12 MPa. The 0.15 MPa internal channel pressure is always higher than the system pressure inside the reactor, effectively preventing the reaction liquid from backflowing into the internal channel through the outlet, thus avoiding polymerization within the channel and blockage of the outlet. The continuously introduced trace amount of inert gas also forms a stable gas curtain near the outlet, further preventing high-viscosity materials from backflowing and adhering to the edge of the outlet, ensuring the long-term unobstructed flow of the internal channel and the outlet, and ensuring that the targeted pumping action can be executed stably and reliably under emergency conditions. When the mixture pumping action is triggered, the control unit simultaneously stops the inert gas supply to prevent airflow from affecting the pumping accuracy and dispersion effect of the mixture; after the pumping action is completed, the control unit immediately resumes the inert gas supply to re-establish the positive pressure protection of the internal channel.

[0153] S6 steady-state recovery and polymerization reaction tailing control

[0154] This step closely follows the decoupling state collaborative intervention process initiated by S4 and the center burst polymerization targeted emergency response process of S5. It is the core closing link of the entire polymerization reaction closed-loop control. It is necessary to accurately determine the complete elimination of the decoupling effect and to achieve a stable and orderly recovery of the system's operating state, ultimately completing the controllable closing of the polymerization reaction and the preparation of the finished product.

[0155] S61 Continuity determination of steady-state recovery condition

[0156] Throughout the execution of the S4 collaborative intervention and S5 emergency response actions, the control unit continuously uses a 1-second data acquisition cycle identical to the previous process to simultaneously monitor the system's heating rate and normalized deviation coefficient—two core judgment parameters—and continuously track the system's steady-state recovery. The control unit invokes the pre-defined stability threshold and preset decoupling threshold from S1, where the stability threshold is set at 0.2℃ / min and the decoupling threshold at 0.15. These two core parameters completely correspond to the core indicators for determining the decoupling state in the previous process, ensuring consistency in the judgment logic and avoiding misjudgments due to inconsistent judgment standards. The 0.2℃ / min stability threshold corresponds to the normal temperature rise level during the stable phase of styrene-butadiene latex free radical polymerization. When the heating rate continuously falls below this threshold, it can be confirmed that the heat accumulation in the central region of the system has been completely eliminated, and the polymerization reaction rate has returned to a stable and controllable range. The preset decoupling threshold of 0.15 is the critical node for determining the decoupling state. Thanks to the dynamic compensation mechanism of the rotation speed ratio introduced when calculating the normalized deviation coefficient, the interference of sudden rotation speed changes during the intervention period has been completely eliminated. Therefore, when the compensated normalized deviation coefficient truly and continuously falls below this threshold, it can be reliably confirmed that the high-viscosity cold boundary layer in the near-wall region has been completely broken up and dissipated, and the material viscosity difference and flow field state in the near-wall and central regions of the reactor have substantially recovered to the homogeneous steady-state level of normal polymerization. When the heating rate is continuously monitored to be less than the set stability threshold, and the normalized deviation coefficient is less than the preset decoupling threshold, and the stable state of both indicators continuously covers no less than 3 consecutive judgment cycles, the control unit finally determines that the heat-shear force decoupling state of the system has been completely eliminated, and the reaction system as a whole has recovered to the homogeneous steady state, and then initiates the orderly recovery action of the system operation state. The multi-cycle continuous stability judgment requirement can effectively filter out misjudgments caused by instantaneous fluctuations in the system, avoid premature recovery of the normal control mode and repeated decoupling states, and ensure the stability of the entire process control.

[0157] Orderly restoration of S62 system operation status

[0158] After confirming that the system has returned to a homogeneous steady state, the control unit executes the system operation state recovery actions in sequence according to the logic that is reversed with the previous intervention actions, so as to ensure a smooth switch of control mode and avoid the stability impact of sudden state changes on the ongoing polymerization reaction.

[0159] The control unit first sends a command to the coolant control unit of the jacket to stop the periodic alternating on / off and asynchronous timing control of the coolant in each section of the jacket, ending the pulse cooling mode. Next, the control unit synchronously sends commands to the variable frequency drive units of the outer and inner agitators to restore the operating speeds of both agitators to the reference speeds before speed adjustment, allowing the flow field inside the reactor to return to the stable mixing and mass transfer state required for a conventional polymerization reaction. Subsequently, the control unit sends a command to the reagent delivery unit to completely stop the pumping of the emergency mixture, and simultaneously sends a command to the inert gas supply unit to resume the continuous flow of high-purity nitrogen into the internal channels of the inner agitator, maintaining the positive pressure and anti-clogging protection state of the internal channels. Regardless of whether the mixture pumping action was triggered earlier, this reset command does not affect the normal operation of the system. Finally, the control unit restores the coolant flow PID control loop based on the center temperature under normal operating conditions, recalls the PID parameters before the stoppage, and re-maintains the isothermal polymerization reaction through mature conventional temperature control logic, ensuring the smooth progress of the subsequent polymerization final stage.

[0160] S63 polymerization reaction completion and product preparation

[0161] After the system fully recovers to the normal polymerization mode, the control unit continuously monitors the overall progress of the polymerization reaction. It tracks the monomer conversion rate in real-time by monitoring the system's real-time torque and internal temperature trends, combined with intermittent sampling and testing. The monomer conversion rate is calculated from the solid content of the sampled system using the formula: Monomer Conversion Rate = (Measured Solid Content - Theoretical Non-volatile Content) / Theoretical Total Monomer Content × 100%. This calculation method is a commonly used conversion rate detection method in the field of styrene-butadiene emulsion polymerization and accurately reflects the progress of the polymerization reaction. When the monomer conversion rate reaches a preset target value of 98% or higher, the control unit triggers a polymerization termination operation, adding a matching terminator aqueous solution to the system to terminate the polymerization reaction. A monomer conversion rate target of over 98% ensures that the polymerization reaction reaches the designed reaction depth, guaranteeing that the final latex product's core indicators such as solid content, molecular weight distribution, and adhesion performance fully meet the stringent requirements of artificial turf back coating applications.

[0162] After the polymerization reaction is terminated, the material in the reactor is transferred to the subsequent post-processing steps. First, unreacted residual monomers are removed from the material through a reduced-pressure flash evaporation process. The flash evaporation temperature is controlled at 60-80℃, and the vacuum degree is controlled at -0.08MPa to -0.095MPa to ensure that the residual monomer content is below 100ppm. Then, the material is filtered through a 100-200 mesh filter to remove trace impurities and agglomerates. Finally, the solid content and pH value are precisely adjusted to control the solid content of the finished latex at 50±2% and the pH value at 7-9, thus obtaining the finished styrene-butadiene latex product for artificial turf back coating. Through the closed-loop control of the entire process in this solution, the heat-shear force decoupling effect during the peak of polymerization exothermic reaction is resolved at its source, effectively inhibiting the formation of micro-gel clusters. The final styrene-butadiene latex has the characteristics of narrow particle size distribution, low gel content, excellent permeability to the substrate, and strong adhesion to grass fibers, which can completely solve the back coating application defects and finished product quality problems caused by gel in the existing technology.

[0163] This method, through a two-level nested decision logic, can accurately capture the critical window of decoupling state, significantly improving the accuracy and foresight of state identification compared to the single-parameter decision-making of existing technologies. By synergistically adjusting the stirring speed, pulsed cooling, and targeted drug delivery, it acts on four core dimensions: heat source control, flow field reconstruction, heat transfer enhancement, and reaction blocking, forming a mutually reinforcing synergistic effect. This effectively resolves the heat-shear force decoupling effect during the peak of polymerization exothermics, fundamentally inhibiting the occurrence of boundary layer microgelation. The resulting styrene-butadiene latex possesses characteristics such as narrow particle size distribution, low gel content, excellent backing material permeability, and strong grass fiber adhesion, significantly improving the backing quality and long-term performance of artificial turf. Furthermore, the hardware used in this solution consists of mature industrial equipment commonly used in the field of polymer polymerization. All control steps, parameter thresholds, and formulation ranges are clearly recorded and set according to established principles. Those skilled in the art can fully implement this method based on the content described in this embodiment.

[0164] This application also discloses a styrene latex preparation system for artificial turf back coating, which is used to realize the full-process execution and closed-loop control of the aforementioned styrene-butadiene latex preparation method. The hardware configuration, functional parameters, and control logic of each component of the system are fully matched with the implementation requirements of the preparation method. The core includes four major modules: reaction vessel body, acquisition unit, execution unit, and control unit. The modules establish bidirectional communication connections to jointly realize the precise and stable control of the entire polymerization reaction process.

[0165] The reactor uses a pressure-resistant stainless steel polymer vessel body with a jacketed structure on the outer wall. The jacket consists of three independent segmented jackets, corresponding to the upper, middle, and lower sections of the vessel body. Each segmented jacket inlet is equipped with a high-frequency switching solenoid valve, which can independently control the on / off state and timing of the coolant. Inside the vessel body are two completely independently driven stirring devices. The first is an outer agitator with an anchor-type scraper structure, where the outer edge of the impeller blades is tightly attached to the inner wall of the vessel. The second is an inner agitator with a multi-stage turbine impeller structure. Its rotating shaft is hollow, forming a continuous internal channel. Multiple sets of liquid outlet holes are evenly distributed along the axial and circumferential directions on the sidewall of the rotating shaft, radially penetrating the sidewall of the rotating shaft and connecting the internal channel with the reaction system inside the vessel.

[0166] The data acquisition unit provides real-time data support for the entire system process, and its core components include a temperature acquisition unit and a torque acquisition unit. The temperature acquisition unit includes multiple temperature probes inserted into the central region of the reaction system, and an array of near-wall temperature sensors attached to the inner wall of the vessel, capable of acquiring real-time data on the center and near-wall temperatures of the reaction system. The torque acquisition unit is integrated into the drive shafts of the two agitators, capable of acquiring real-time dynamic torque data of the outer and inner agitators, with an acquisition frequency of at least 1Hz.

[0167] The execution unit receives instructions from the control unit and performs various actions during the polymerization process. Its core components include a frequency converter drive unit, a coolant control unit, a reagent delivery unit, and an inert gas supply unit. The frequency converter drive unit is electrically connected to the drive motors of the two agitators and can receive control commands to independently adjust the operating speed of the two agitators, with a speed adjustment accuracy of no less than 1 rpm. The coolant control unit is connected to the high-frequency solenoid valves of each segment jacket and can receive control commands to adjust the on / off state, opening / closing cycle, and asynchronous on / off sequence of the coolant. The reagent delivery unit's outlet is connected to the internal channel of the inner agitator, allowing for controlled and precise pumping of a pre-cooled chain transfer agent and terminator mixture into the internal channel. The inert gas supply unit's output port is connected to the internal channel of the inner agitator and can receive control commands to introduce high-purity nitrogen into the internal channel, precisely maintaining stable gas pressure within the internal channel.

[0168] The control unit serves as the system's central control hub, establishing bidirectional communication connections with the acquisition unit and all execution units. The latency for data processing and command issuance throughout the entire process does not exceed 200ms. The control unit pre-stores and solidifies the core control thresholds and parameters for the entire polymerization process. It can fully execute the entire process control logic of the aforementioned preparation method, including synchronous data acquisition, real-time calculation of core parameters, two-level nested state determination, decoupled state collaborative intervention, targeted emergency response to central burst polymerization risk, system steady-state recovery, and polymerization termination. It can accurately identify and resolve the heat-shear force decoupling effect during the peak of exothermic polymerization, fundamentally suppressing the occurrence of boundary layer microgelation and ensuring the stable and controllable polymerization reaction of styrene-butadiene latex.

[0169] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing styrene-butadiene latex for back coating of artificial turf, characterized in that, The method, employing a reaction vessel equipped with a jacket, an outer stirrer, and an inner stirrer with internal channels, includes: When the temperature of the reaction system is lower than the preset exothermic temperature, the torque of the outer and inner stirrers is collected to establish the outer reference torque and the inner reference torque. When the temperature of the reaction system reaches the exothermic temperature, the center temperature of the central region of the reaction system, the near-wall temperature of the inner wall region of the reactor, and the real-time rotation speed and real-time torque of the outer and inner stirrers are obtained. When the heating rate of the center temperature is greater than the preset rate threshold, and the temperature difference between the center temperature and the near-wall temperature is greater than the preset temperature difference threshold, and the normalized deviation coefficient determined by the real-time rotation speed, real-time torque and the corresponding reference rotation speed, reference torque is greater than the preset decoupling threshold, the rotation speed of the inner agitator is reduced, the rotation speed of the outer agitator is increased, and the coolant flowing into the jacket is switched to periodic opening and closing flow. During the speed adjustment, if the real-time torque of the inner agitator is greater than the preset sudden change threshold, a mixture containing chain transfer agent and terminator is pumped into the central region through the internal channel. When the heating rate and the normalized deviation coefficient fall back to the preset range, the state before the speed adjustment is restored, and styrene-butadiene latex is obtained.

2. The method according to claim 1, characterized in that, The establishment of the outer layer reference torque and the inner layer reference torque includes: Within a set time window during which the reaction system is operating and the temperature is below the preset exothermic temperature, multiple torque data of the outer and inner stirrers are acquired according to a set acquisition cycle. The acquired torque data of the outer and inner agitators are averaged to generate the outer reference torque and inner reference torque respectively.

3. The method according to claim 2, characterized in that, The steps for obtaining the heating rate and the normalized deviation coefficient include: The differential of the real-time acquired center temperature is used as the heating rate; When the heating rate is greater than the preset rate threshold within a set number of consecutive determination cycles, the real-time torque of the outer layer stirrer is divided by the outer layer reference torque, and then divided by the ratio of the real-time rotation speed of the outer layer stirrer to the corresponding reference rotation speed to obtain the outer layer torque ratio; and the real-time torque of the inner layer stirrer is divided by the inner layer reference torque, and then divided by the ratio of the real-time rotation speed of the inner layer stirrer to the corresponding reference rotation speed to obtain the inner layer torque ratio. The normalized deviation coefficient is generated by subtracting the inner layer torque ratio from the outer layer torque ratio.

4. The method according to claim 3, characterized in that, The steps of reducing the speed of the inner agitator, increasing the speed of the outer agitator, and switching the coolant flowing into the jacket to a periodic on-off flow include: Reduce the rotation speed of the inner agitator according to the set decrease range; The rotation speed of the outer agitator is increased synchronously according to a set rate of change in order to strip the reaction liquid from the inner wall area of ​​the reactor. The coolant supplied to the jacket is switched on and off alternately according to a set time period to form the periodic opening and closing flow, which is synchronized with the increase in the rotation speed of the outer agitator.

5. The method according to claim 4, characterized in that, The pumping of a mixture containing a chain transfer agent and a terminator into the central region via the internal channel includes: During the cycle of increasing the speed of the outer stirrer to perform stripping on the reaction solution, the instantaneous rate of change of the real-time torque of the inner stirrer is extracted; When the real-time torque of the inner agitator is greater than the preset sudden change threshold and the instantaneous change rate is greater than the set change rate threshold, the temperature of the mixture is configured to be lower than the set temperature threshold and pumped into the central region through the internal channel. The pumping cycle of the mixture overlaps with the cycle of the rotational speed increase of the outer agitator.

6. The method according to claim 5, characterized in that, The inner agitator is configured to have a liquid outlet communicating with the internal channel; the method further includes: During pumping cycles other than those of the mixture, inert gas is introduced into the internal channel to set the gas pressure in the internal channel to be greater than a set gas pressure threshold, so as to block the reaction liquid from entering the internal channel through the liquid outlet. When the mixture is triggered to be pumped into the central region through the outlet, the inert gas is stopped from being supplied to the internal channel.

7. The method according to claim 6, characterized in that, The process of restoring the state before the speed adjustment includes: When the heating rate is less than the set stable threshold and the normalized deviation coefficient is less than the preset decoupling threshold, the alternating on / off of the coolant flowing into the jacket is stopped. The rotation speeds of the inner and outer agitators are restored to their original states before the speed adjustment. Stop pumping the mixture in and resume the flow of the inert gas into the internal channel.

8. The method according to claim 4, characterized in that, The jacket configuration includes multiple independent segmented jackets; The alternating switching on and off of the coolant supplied to the jacket includes: A set phase delay time is configured between adjacent segmented jackets; According to the phase delay time, the switching on and off actions of each segment jacket on the coolant are triggered sequentially and in staggered order. The adjacent segmented jackets are configured to maintain an asynchronous on / off state within the same set time period.

9. The method according to claim 7, characterized in that, The method further includes: When the normalized deviation coefficient is less than the preset decoupling threshold, the flow rate of the coolant entering the jacket is adjusted based on the obtained center temperature. When the coolant flowing into the jacket is switched to the periodic on-off flow, the adjustment of the coolant flow rate into the jacket based on the center temperature is stopped. When the alternating on / off of the coolant supplied to the jacket is stopped, the regulation of the coolant flow rate supplied to the jacket based on the center temperature is resumed.

10. A styrene-butadiene latex preparation system for back coating of artificial turf, characterized in that, The system for implementing the method as described in any one of claims 1 to 9 comprises: A reaction vessel comprising a jacket, an outer agitator, and an inner agitator with internal channels, and a control unit communicatively connected to the jacket, the outer agitator, and the inner agitator, the control unit being configured to perform the following operations: When the temperature of the reaction system is lower than the preset exothermic temperature, the torque of the outer and inner stirrers is collected to establish the outer reference torque and the inner reference torque. When the temperature of the reaction system reaches the exothermic temperature, the center temperature of the central region of the reaction system, the near-wall temperature of the inner wall region of the reactor, and the real-time rotation speed and real-time torque of the outer and inner stirrers are obtained. When the heating rate of the center temperature is greater than the preset rate threshold, and the temperature difference between the center temperature and the near-wall temperature is greater than the preset temperature difference threshold, and the normalized deviation coefficient determined by the real-time rotation speed, real-time torque and the corresponding reference rotation speed, reference torque is greater than the preset decoupling threshold, the rotation speed of the inner agitator is reduced, the rotation speed of the outer agitator is increased, and the coolant flowing into the jacket is switched to periodic opening and closing flow. During the speed adjustment, if the real-time torque of the inner agitator is greater than the preset sudden change threshold, the mixture containing chain transfer agent and terminator is pumped into the central region through the internal channel. When the heating rate and the normalized deviation coefficient fall back to the preset range, the state before the speed adjustment is restored.

Images