An automatic control system and method for monitoring the viscosity of chemically synthesized hot melt adhesives.

Abstract

This invention discloses an automatic control system and method for monitoring the viscosity of chemically synthesized hot melt adhesives, relating to the field of viscosity monitoring technology for chemically synthesized hot melt adhesives. The system includes: an online viscosity monitoring module that can be directly embedded in the hot melt adhesive synthesis reaction system for real-time acquisition of apparent viscosity data, reaction temperature data, and shear rate data of the hot melt adhesive during the synthesis process; a data processing module for receiving real-time data acquired by the online viscosity monitoring module, performing noise reduction, calibration, and fitting processing on the data, comparing it to a preset hot melt adhesive viscosity standard threshold, and generating a corresponding control command if the threshold is exceeded; an automatic control module for responding to the control commands generated by the data processing module; and a control module. This invention enables real-time, accurate online monitoring and, based on the monitoring data, completes automated and intelligent viscosity control, improving the quality consistency of hot melt adhesive products and enhancing industrial production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of viscosity monitoring technology for chemically synthesized hot melt adhesives, and specifically relates to an automatic control system and method for monitoring the viscosity of chemically synthesized hot melt adhesives. Background Technology

[0002] Chemically synthesized hot melt adhesives are widely used in various industrial fields such as packaging, automobile manufacturing, electronic device assembly, and wood processing due to their solvent-free, rapid curing, and excellent bonding properties. As a core process and performance indicator, viscosity directly determines the fluidity, coating uniformity, and final bonding effect of hot melt adhesives in the molten state. Therefore, accurate monitoring and control of viscosity during the chemical synthesis of hot melt adhesives is a key link to ensure product quality stability.

[0003] Currently, the industry's methods for monitoring the viscosity of chemically synthesized hot melt adhesives are mainly offline sampling and testing, adhering to testing standards such as ASTM D3236-88. The mainstream testing equipment is the Brookfield rotational viscometer, supplemented by capillary viscometers, thermomechanical analyzers, and other devices. In some testing scenarios, cone-plate and parallel-plate viscometers are used to complete rheological property analysis. The specific testing process involves taking a sample from the synthesis reaction system, heating the hot melt adhesive to a molten state at around 175°C, and measuring the apparent viscosity at different shear rates and temperatures using a viscometer. The temperature-viscosity curve is then plotted using curve analysis software to determine whether the hot melt adhesive viscosity meets the process requirements. In a few testing scenarios, vibration-type or ultrasonic viscometers are used to attempt simple online viscosity testing, but these methods have low detection accuracy and cannot be adapted to the high-temperature and dynamic reaction environment during the hot melt adhesive synthesis process. Existing technologies for controlling the viscosity of chemically synthesized hot melt adhesives typically rely on offline viscosity testing data and are centered on manual, post-processing control. These methods fall into two main categories: First, formulation control, which involves adding viscosity modifiers such as paraffin wax or low-molecular-weight polyethylene to the synthesis system based on offline viscosity testing results. By adjusting the type and amount of these modifiers, the degree of molecular chain entanglement in the hot melt adhesive matrix resin is altered, thereby controlling the viscosity. Second, process parameter control, which involves manually adjusting process parameters such as mixing speed, reaction temperature, isothermal time, and processing pressure during the hot melt adhesive synthesis process based on viscosity testing data. Alternatively, the grafting process of functional monomers can be optimized using a segmented isothermal method to alter the melt flow characteristics of the hot melt adhesive and achieve viscosity control.

[0004] However, since the monitoring and control process is highly dependent on manual operation, sample processing, parameter setting and data reading in the detection stage, and viscosity modifier addition and process parameter adjustment in the control stage all need to be done manually. This not only results in low operational efficiency, but also easily leads to deviations in detection data and insufficient control accuracy due to human error, further reducing the stability of product quality. Summary of the Invention

[0005] The purpose of this invention is to provide an automatic control system and method for monitoring the viscosity of chemically synthesized hot melt adhesives. This system can achieve real-time and accurate online monitoring, and automatically and intelligently control the viscosity based on the monitoring data, thereby improving the quality consistency of hot melt adhesive products and increasing the efficiency of industrial production, thus solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: An automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesives includes: an online viscosity monitoring module that can be directly embedded in the hot melt adhesive synthesis reaction system, used to collect the apparent viscosity data, reaction temperature data and shear rate data of the hot melt adhesive in real time during the synthesis process; The data processing module is used to receive real-time data collected by the online viscosity monitoring module, perform noise reduction, calibration and fitting processing on the data, plot the real-time temperature and viscosity change curve, compare it with the preset hot melt adhesive viscosity standard threshold, determine whether the current hot melt adhesive viscosity meets the process requirements, and generate corresponding control instructions if it exceeds the threshold. The automatic control module includes an automatic formulation control unit for accurately metering and adding viscosity modifiers, and an automatic process parameter control unit for automatically adjusting the mixing speed, reaction temperature and isothermal time during the synthesis process, in response to control commands generated by the data processing module. The control module coordinates the collaborative work of the online viscosity monitoring module, data processing module, and automatic control module, stores real-time monitoring data, control parameters, and historical data, and performs closed-loop control of viscosity monitoring and regulation.

[0007] Preferably, the online viscosity monitoring module adopts a flange-type sealing embedded structure to be embedded in the hot melt adhesive synthesis reaction system, thereby achieving integration with the hot melt adhesive synthesis reaction system.

[0008] Preferably, the online viscosity monitoring module includes a cone-plate rheological sensor, a temperature sensor, a shear rate detection unit, a signal processing unit, and a data transmission unit. The cone-plate probe of the cone-plate rheological sensor is sealed and fixed to the reaction vessel through a fluororubber seal. The probe of the temperature sensor is embedded in parallel with the cone-plate probe of the cone-plate rheological sensor, both passing through the fluororubber seal. The signal output terminals of the cone-plate rheological sensor, the temperature sensor, and the shear rate detection unit are all connected to the input terminal of the signal processing unit. The signal output terminal of the signal processing unit is connected to the signal input terminal of the data transmission unit. The data transmission unit establishes communication with the data processing module via wired or wireless means.

[0009] Preferably, the data processing module includes a noise reduction processing unit for eliminating interference signals in the original data, a calibration processing unit for correcting systematic errors in the detection data, a data fitting unit for fitting the temperature-viscosity relationship curve, a curve plotting unit for generating real-time temperature-viscosity change curves, a threshold comparison unit for determining whether the viscosity meets the process requirements, and an instruction generation unit for generating corresponding control instructions. The noise reduction processing unit, calibration processing unit, data fitting unit, curve plotting unit, threshold comparison unit, and instruction generation unit are connected in sequence.

[0010] Preferably, the process by which the curve plotting unit generates real-time temperature and viscosity change curves is as follows: A1. Sort the calibrated temperature and the fitted viscosity by timestamp to ensure data time sequence consistency; A2. Set the horizontal axis to temperature and the vertical axis to viscosity, and map each timestamp to a point on the coordinate plane. A3. Linear interpolation is used to connect adjacent data points to form a real-time temperature and viscosity change curve; A4. Receive new data every 50ms, update the curve data points, and realize dynamic curve refresh.

[0011] Preferably, the threshold comparison unit compares the current fitted real-time viscosity value with a preset viscosity standard threshold range. When the real-time viscosity value is within the viscosity standard threshold range, a qualified signal is output to maintain the current process parameters. When the real-time viscosity value is greater than the maximum value of the viscosity standard threshold range, a viscosity-to-high signal is output to trigger a viscosity-reducing control command. When the real-time viscosity value is less than the minimum value of the viscosity standard threshold range, a viscosity-to-low signal is output to trigger a viscosity-increasing control command. Finally, the judgment result and the corresponding control command are transmitted to the control module.

[0012] Preferably, the automatic formulation control unit includes: a corrosion-resistant storage tank for storing viscosity modifier, and a liquid level sensor is installed inside the corrosion-resistant storage tank; A metering unit for precisely metering the amount of regulator added includes a plunger metering pump and a flow sensor installed on the plunger metering pump line; The delivery pipeline is used to transport the regulator to the reaction system, and the metering pump outlet is connected to the delivery pipeline; The control unit used to adjust the addition rate includes a servo controller and a PID control module; A valve unit for controlling the on / off state of a pipeline includes an electromagnetic shut-off valve. The outlet of the corrosion-resistant storage tank is connected to the electromagnetic shut-off valve via a flange, and the outlet of the electromagnetic shut-off valve is connected to the inlet of a plunger metering pump. The mixing unit includes a static mixer installed at the addition port, the end of the delivery pipeline is connected to the static mixer, and the outlet of the static mixer is embedded inside the reactor. The signal output terminals of the level sensor and flow sensor are connected to the signal input terminal of the control unit; the control output terminal of the control unit is connected to the servo motor of the plunger metering pump and the coil of the electromagnetic shut-off valve.

[0013] Preferably, the automatic formulation control unit performs the following process for precise metering and addition of viscosity modifier: B1. The servo controller receives control commands from the control module, which include the type of regulator, the target amount to be added, and the duration of addition. B2. The remaining amount of regulator in the corrosion-resistant storage tank is detected by the liquid level sensor. If it is lower than the minimum liquid level threshold, a replenishment alarm is issued; if it is sufficient, the solenoid shut-off valve is opened. B3. Calculate the required real-time addition rate based on the target addition amount and addition duration; B4. The flow sensor collects the actual added flow rate in real time, and the PID adjustment module compares the actual added flow rate with the target rate, and outputs a control signal to adjust the servo motor speed of the plunger metering pump. B5. The plunger metering pump outputs a corresponding displacement of regulator according to the rotation speed, ensuring that the actual addition amount is consistent with the target addition amount. B6. The regulator is delivered to the static mixer via the delivery pipeline and quickly mixed with the hot melt adhesive in the reactor. When the cumulative addition reaches the target addition amount, the electromagnetic shut-off valve and the plunger metering pump are closed, and a signal indicating that the addition is complete is sent back to the control module.

[0014] Preferably, the automatic process parameter control unit includes: a temperature control subunit for adjusting the temperature of the reaction system, including a temperature controller, an electric heating element and a cooling coil, wherein a solenoid valve for controlling the flow of coolant is installed on the cooling coil, and the temperature controller is electrically connected to the solenoid valve on the electric heating element and the cooling coil. A speed control subunit for controlling the speed of the mixing rotor includes a frequency converter and a three-phase asynchronous motor; The isothermal time control subunit, which controls the duration of isothermal maturation, includes a logic controller and a timer; The feedback sensing unit, used for real-time feedback of actual process parameters, mainly consists of a PT100 temperature sensor and a speed sensor. An actuator unit used to execute temperature and speed control commands includes a contactor, a relay, and a regulating valve; Safety protection units used to prevent process parameters from exceeding safe ranges include alarm modules and emergency stop switches; The output of the frequency converter driver is connected to a three-phase asynchronous motor, which is connected to the mixing rotor of the reactor via a coupling. The electric heating tube is embedded in the reactor jacket, and the cooling coil is connected to an external cooling water pump. The signal outputs of the PT100 temperature sensor and speed sensor are connected to the signal inputs of each control subunit. The control outputs of each control subunit are connected to contactors and relays. The safety protection unit is linked with the temperature control subunit, speed control subunit, and constant temperature time control subunit. When an alarm is triggered, the power supply to the actuator is cut off via an emergency stop switch.

[0015] Based on the above-described automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesives, this invention also provides an automatic control method for monitoring the viscosity of chemically synthesized hot melt adhesives, comprising the following steps: S1. Preset the viscosity standard threshold, reaction temperature range, shear rate range, and viscosity modifier addition amount calibration parameters of the chemically synthesized hot melt adhesive, start the online viscosity monitoring module, data processing module, and automatic control module, and complete the self-test and linkage debugging of each module. S2. Embed the online viscosity monitoring module into the hot melt adhesive synthesis reaction system to collect the apparent viscosity data, reaction temperature data and shear rate data of the hot melt adhesive in real time during the synthesis process, and transmit them to the data processing module in an instant. S3. The data processing module performs noise reduction and calibration on the received raw data to eliminate detection errors caused by high temperature environment and reaction disturbance. It fits and plots the real-time temperature-viscosity change curve, compares it with the preset threshold to determine whether the viscosity is qualified. If it is qualified, the process parameters are maintained. If it is not qualified, the control command is generated and transmitted to the control module. S4. After receiving the control command, the control module drives the automatic control module to perform precise control. S5. The online viscosity monitoring module continuously collects the viscosity data after adjustment, repeats S3-S4 until the hot melt adhesive viscosity is qualified, and the control module records the adjustment parameters and combines them with historical data to automatically optimize the response speed and amplitude of subsequent adjustments, thus completing the adaptive optimization of viscosity monitoring and adjustment.

[0016] The automatic control system and method for monitoring the viscosity of chemically synthesized hot melt adhesives proposed in this invention have the following advantages compared with the prior art: 1. This invention constructs a closed-loop system of monitoring, processing, regulating and feedback through the coordinated operation of an online viscosity monitoring module, a data processing module, an automatic regulation module and a control module. This ensures that regulation commands can quickly respond to real-time monitoring data, shorten the response time of viscosity regulation, avoid large fluctuations in the viscosity of hot melt adhesives, and further improve the stability of product quality.

[0017] 2. This invention directly embeds an online viscosity monitoring module into the synthesis reaction system to collect data in real time, thereby improving detection accuracy and effectively avoiding data distortion caused by changes in the temperature and shear state of the hot melt adhesive during sampling. It can truly reflect the real-time viscosity state of the hot melt adhesive in the reaction system, providing reliable data support for subsequent precise control. 3. This invention, through an automatic formula control unit and an automatic process parameter control unit, responds to the control commands generated by the data processing module. It can automatically adjust process parameters such as the precise metering and addition of viscosity modifier, mixing speed, and reaction temperature without manual intervention. This completely eliminates the dependence on operator experience and avoids problems such as detection deviation and inaccurate control range caused by manual operation. It greatly improves the accuracy and consistency of viscosity control and effectively ensures the stability of hot melt adhesive melt flow, coating uniformity, and bonding performance. 4. This invention standardizes the operation of viscosity monitoring and control through a complete process of system initialization, real-time monitoring, data processing and judgment, automatic control execution, and closed-loop feedback optimization. It avoids the problems of non-standard operation and arbitrary parameter adjustment in the existing manual control process, and ensures that the viscosity control process of hot melt adhesives in different batches and different production periods is uniform and controllable, further improving the control accuracy and product quality consistency. Attached Figure Description

[0018] Figure 1 A system block diagram according to an embodiment of the present invention is shown; Figure 2 A block diagram of an online viscosity monitoring module according to an embodiment of the present invention is shown; Figure 3 A block diagram of an automatic formula control unit according to an embodiment of the present invention is shown; Figure 4 A block diagram of an automatic process parameter control unit according to an embodiment of the present invention is shown; Figure 5 A flowchart illustrating the process of generating real-time temperature and viscosity change curves according to an embodiment of the present invention is shown. Figure 6 A flowchart of a method according to an embodiment of the present invention is shown. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides, for example Figure 1-5 An automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesives is shown, including an online viscosity monitoring module, a data processing module, an automatic control module, and a control module. The online viscosity monitoring module can be directly embedded in the hot melt adhesive synthesis reaction system to collect the apparent viscosity data, reaction temperature data, and shear rate data of the hot melt adhesive in real time during the synthesis process. The hot melt adhesive synthesis reaction system is centered on the polymerization or grafting reaction of the base resin, combined with the processes of raw material mixing, melting, and curing. Specifically, the base resin, functional monomers, initiators, and tackifiers are added to a mixing reactor according to the actual requirements. The reactor is heated by heat transfer oil in the jacket or by electric heating to raise the system temperature to 160-90℃. The mixing rotor is started at a speed of 30 to 80 r / min to melt and uniformly mix the solid raw materials to form a homogeneous melt. The initiator decomposes at high temperature to generate free radicals, which initiate the grafting polymerization reaction between the base resin and the functional monomers. By adjusting the reaction temperature and rotation speed, the molecular chain growth rate is controlled to form a polymer with the target molecular weight distribution. After the reaction is completed, the temperature is maintained at 170-180℃ and the rotation speed is 20-40 r / min for constant temperature curing to eliminate internal stress and stabilize the melt viscosity. After curing, the molten hot melt adhesive is transported to the subsequent coating or molding process through the discharge port at the bottom of the reactor.

[0021] The online viscosity monitoring module adopts a flange-sealed embedded structure into the hot melt adhesive synthesis reaction system, achieving integration with the system. Specifically, a standardized flange interface is reserved on the side wall of the reactor, with a built-in fluororubber gasket resistant to ≥250℃ to ensure sealing under high-temperature molten conditions. The sensing probe of the online viscosity monitoring module is made of corrosion-resistant alloy material, such as Hastelloy, and is fixed to the interface with flange bolts. The probe tip is directly immersed in the hot melt adhesive synthesis reaction system to a depth of 1 / 3-2 / 3 of the effective volume of the reactor to avoid liquid level fluctuations affecting the detection. The main body of the online viscosity monitoring module is installed outside the reactor and includes a signal processing and transmission unit, which is connected to the probe via a high-temperature shielded cable. The cable is covered with a heat-insulating protective sleeve to prevent damage to the circuitry from the high-temperature environment.

[0022] like Figure 2As shown, the online viscosity monitoring module includes a cone-plate rheological sensor, a temperature sensor, a shear rate detection unit, a signal processing unit, and a data transmission unit. The cone-plate probe of the cone-plate rheological sensor is sealed and fixed to the reaction vessel through a fluororubber seal. The probe of the temperature sensor is embedded in parallel with the cone-plate probe of the cone-plate rheological sensor, both passing through the fluororubber seal. The signal output terminals of the cone-plate rheological sensor, the temperature sensor, and the shear rate detection unit are all connected to the input terminal of the signal processing unit. The signal output terminal of the signal processing unit is connected to the signal input terminal of the data transmission unit. The data transmission unit establishes communication with the data processing module via wired or wireless means.

[0023] In this cone-plate rheological sensor, the fixed cone and the rotating cone form a shear gap with a width of 0.05~0.1mm. The rotating cone is driven to rotate synchronously by the reactor's internal mixing rotor. Hot melt adhesive fills the gap. The shear rate detection unit includes a Hall effect speed sensor and a torque sensor. The speed sensor collects the rotational speed of the rotating cone and converts it into the shear rate. The shear rate conversion formula is: , In the formula, Shear rate, The rotational speed of the cone. Let be the radius of the cone plate. The gap between the cone and the plate; A torque sensor detects the shear torque acting on a fixed cone, and the shear stress is calculated using the sensor's structural parameters (i.e., cone radius R and cone angle θ). The formula for calculating the shear stress is: , In the formula, Where M is the shear stress, M is the value detected by the torque sensor, and R is the radius of the cone plate; The signal processing unit uses an ADC converter. The unit converts shear stress and shear rate into apparent viscosity using an algorithm. The apparent viscosity conversion formula is as follows: In the formula, For shear stress, Shear rate, This refers to the apparent viscosity.

[0024] The temperature sensor directly contacts the molten hot melt adhesive. It converts the temperature signal into a resistance signal by observing the change in resistance with temperature. This resistance signal is then amplified by the operational amplifier in the signal processing unit and converted into digital temperature data by the ADC converter. The formula for the change in resistance with temperature is: , In the formula, The resistance value is given by T, where T is the temperature of the reaction system. This is the standard resistance value at 0℃. This is a primary temperature coefficient. It is a second-order temperature coefficient.

[0025] The data transmission unit includes an RS485 bus module and a wireless LoRa module, which facilitates signal transmission via wired or wireless means; The data processing module is used to receive real-time data collected by the online viscosity monitoring module, perform noise reduction, calibration and fitting processing on the data, plot the real-time temperature and viscosity change curve, compare it with the preset hot melt adhesive viscosity standard threshold, determine whether the current hot melt adhesive viscosity meets the process requirements, and generate corresponding control instructions if it exceeds the threshold. The data processing module includes a noise reduction processing unit for eliminating interference signals in the original data, a calibration processing unit for correcting systematic errors in the detection data, a data fitting unit for fitting the temperature-viscosity relationship curve, a curve plotting unit for generating real-time temperature-viscosity change curves, a threshold comparison unit for determining whether the viscosity meets the process requirements, and an instruction generation unit for generating corresponding control commands. The noise reduction processing unit, calibration processing unit, data fitting unit, curve plotting unit, threshold comparison unit, and instruction generation unit are connected in sequence. The noise reduction unit uses a moving average algorithm to reduce noise in the original data. The moving average algorithm formula is as follows: , in, For the i-th denoised data, Let k be the i-th original data, and k be the size of the sliding window; The standard processing unit retrieves pre-stored standard calibration curve parameters, which are obtained through calibration using standard viscosity samples. The calibrated data is then calculated using a linear calibration formula, which is: , In the formula, For calibrated data, Let A be the i-th denoised data, and let B be the slope of the calibration curve obtained by fitting the standard sample. The data fitting unit uses the least squares algorithm to fit the calibrated temperature and viscosity data, and outputs the fitted viscosity data. The least squares algorithm formula is as follows: , The coefficients are obtained by solving the system of equations: , , , In the formula, For the i-th calibrated viscosity data, For the i-th calibrated temperature data, , and These are the fitting coefficients, and m is the number of data points; like Figure 5 As shown, the process by which the curve plotting unit generates real-time temperature and viscosity change curves is as follows: A1. Sort the calibrated temperature and the fitted viscosity by timestamp to ensure data time sequence consistency; A2. Set the horizontal axis to temperature and the vertical axis to viscosity, and map each timestamp to a point on the coordinate plane. A3. Linear interpolation is used to connect adjacent data points to form a real-time temperature and viscosity change curve; A4. Receive new data every 50ms and update the curve data points to achieve dynamic curve refresh; The threshold comparison unit compares the current fitted real-time viscosity value with a preset viscosity standard threshold range. When the real-time viscosity value is within the viscosity standard threshold range, a qualified signal is output to maintain the current process parameters. When the real-time viscosity value is greater than the maximum value of the viscosity standard threshold range, a high viscosity signal is output, triggering a viscosity reduction control command. When the real-time viscosity value is less than the minimum value of the viscosity standard threshold range, a low viscosity signal is output, triggering a viscosity increase control command. Finally, the judgment result and the corresponding control command are transmitted to the control module. The preset viscosity standard threshold range is set according to the product model. The automatic control module includes an automatic formulation control unit for precise metering and addition of viscosity modifiers, and an automatic process parameter control unit for automatically adjusting the mixing speed, reaction temperature and isothermal time during the synthesis process, in response to control commands generated by the data processing module. like Figure 3As shown, the automatic formulation control unit includes a corrosion-resistant storage tank for storing viscosity modifiers, a metering unit for accurately metering the amount of modifier added, a delivery pipeline for conveying the modifier to the reaction system, a control unit for adjusting the addition rate, a valve unit for controlling the on / off state of the pipeline, and a mixing unit. The metering unit includes a plunger metering pump and a flow sensor installed on the plunger metering pump pipeline. A level sensor is installed inside the corrosion-resistant storage tank. The control unit includes a servo controller and a PID control module. The mixing unit includes a static mixer installed at the addition port. The valve unit includes an electromagnetic shut-off valve. The outlet of the corrosion-resistant storage tank is connected to the electromagnetic shut-off valve of the valve unit via a flange. The outlet of the electromagnetic shut-off valve is connected to the inlet of the plunger metering pump of the metering unit. The outlet of the metering pump is connected to the stainless steel pipeline of the delivery pipeline. The end of the delivery pipeline is connected to the static mixer of the mixing unit. The outlet of the static mixer is embedded inside the reactor. The signal output terminals of the level sensor and the flow sensor are connected to the signal input terminals of the control unit. The control output terminal of the control unit is connected to the servo motor of the plunger metering pump and the coil of the electromagnetic shut-off valve. The control unit communicates with the control module via an RS485 bus.

[0026] The automatic formulation control unit performs the following process for precise metering and addition of viscosity modifiers: B1. The servo controller receives control commands from the control module, which include the type of regulator, the target amount to be added, and the duration of addition. B2. The remaining amount of regulator in the corrosion-resistant storage tank is detected by the liquid level sensor. If it is lower than the minimum liquid level threshold, a replenishment alarm is issued; if it is sufficient, the solenoid shut-off valve is opened. B3. Calculate the required real-time addition rate based on the target addition amount and addition duration. Real-time addition rate = target addition amount / addition duration; B4. The flow sensor collects the actual added flow rate in real time, and the PID adjustment module compares the actual added flow rate with the target rate, and outputs a control signal to adjust the servo motor speed of the plunger metering pump. The formula for calculating the servo motor speed is: , In the formula, Let t be the metering pump speed. The initial rotational speed, This is the proportionality coefficient. The integral coefficient is... Here, v is the differential coefficient, v is the target addition rate, and Q is the actual addition flow rate.

[0027] B5. The plunger metering pump outputs a corresponding displacement of regulator according to the rotation speed, ensuring that the actual addition amount is consistent with the target addition amount. B6. The regulator is delivered to the static mixer via the delivery pipeline and quickly mixed with the hot melt adhesive in the reactor. The delivery pipeline needs to be insulated and the temperature of the insulation layer is maintained at 60-80℃ to prevent solidification. When the cumulative addition reaches the target addition amount, the electromagnetic shut-off valve and the plunger metering pump are closed, and a signal indicating that the addition is complete is fed back to the control module. like Figure 4 As shown, the automatic process parameter control unit includes a temperature control subunit for adjusting the reaction system temperature, a speed control subunit for controlling the speed of the mixing rotor, a constant temperature time control subunit for controlling the duration of constant temperature maturation, a feedback sensing unit for real-time feedback of actual process parameter values, an actuator unit for executing temperature and speed control commands, and a safety protection unit for preventing process parameters from exceeding safe ranges. The temperature control subunit includes a temperature controller, an electric heating element, and a cooling coil. A solenoid valve for controlling the flow of coolant is installed on the cooling coil. The temperature controller is electrically connected to the solenoid valve on the electric heating element and the cooling coil. The speed control subunit includes a frequency converter and a three-phase asynchronous motor, with the frequency converter electrically connected to the three-phase asynchronous motor. The constant temperature time control subunit includes a logic controller and a timer, with the logic controller electrically connected to the timer. The feedback sensing unit mainly consists of a PT100 temperature sensor and a speed sensor. The actuator unit includes a contactor, a relay, and a regulating valve. The safety protection unit includes an alarm module and an emergency stop switch. The variable frequency drive output of the speed control subunit is connected to a three-phase asynchronous motor, which is connected to the mixing rotor of the reactor via a coupling. The electric heating tube of the temperature control subunit is embedded in the reactor jacket, and the cooling coil is connected to an external cooling water pump. The signal outputs of the PT100 temperature sensor and speed sensor of the feedback sensing unit are connected to the signal inputs of each control subunit. The control outputs of each control subunit are connected to the contactors and relays of the actuator unit. The safety protection unit is linked with the temperature control subunit, speed control subunit, and constant temperature time control subunit. When an alarm is triggered, the power supply to the actuator is cut off via an emergency stop switch.

[0028] The automatic process parameter control unit automatically controls process parameters through the following process: C1. The temperature control subunit receives the target temperature T_target from the control module. C2, PT100 temperature sensor collects the actual temperature T_real of the reaction system in real time; C3. Calculate the temperature deviation ΔT based on the target temperature T_target and the actual temperature of the reaction system T_real, i.e., ΔT = T_target - T_real; C4. The control signal U_T is output through the PID algorithm to adjust the heating power of the electric heating tube or the opening of the regulating valve of the cooling coil. If ΔT>0 (temperature is too low), increase the heating power and turn off the cooling coil; If ΔT < 0 (temperature is too high), reduce the heating power and turn on the cooling coil; When |T_real-T_target|≤±0.5℃, the system enters a constant temperature state, and the temperature control subunit maintains the current control output. The automatic process parameter control unit regulates the rotation speed through the following process: D1. The speed control subunit receives the target speed n_target from the control module; D2. The speed sensor collects the actual speed n_real of the mixing rotor in real time; D3. Calculate the speed deviation Δn based on the target speed n_target and the actual speed n_real of the mixing rotor, i.e., Δn = n_target - n_real; D4. The output frequency of the frequency converter driver is adjusted by outputting a control signal U_n through the PID algorithm. D5. Using the formula that shows a linear relationship between frequency and rotational speed, precise speed control can be achieved by changing the frequency. The formula that shows a linear relationship between frequency and rotational speed is: N=60f / p, where N is the adjusted speed of the mixing rotor, f is the frequency, and p is the number of pole pairs of the motor; D6. When |n_real-n_target|≤±1r / min, maintain the current output frequency.

[0029] The automatic process parameter control unit regulates the isothermal time through the following process: F1. When the temperature control process enters the constant temperature state, i.e. (|T_real-T_target|≤±0.5℃), the constant temperature time control subunit is triggered to start timing. F2, the timer accumulates the constant temperature time t_acc in real time; F3. When t_acc reaches the preset constant temperature time t_target, send a signal to the control module that the constant temperature has been completed; if it has not been reached, continue to maintain the current temperature and speed parameters.

[0030] The control module coordinates the collaborative work of the online viscosity monitoring module, data processing module, and automatic control module, stores real-time monitoring data, control parameters, and historical data, and performs closed-loop control of viscosity monitoring and control. The control module includes an STM32H7 microcontroller. During collaborative control, it first receives real-time data from the online viscosity monitoring module, the processing results from the data processing module, and judgment instructions. Then, it converts the control instructions from the data processing module into control signals that the CPU can recognize, such as "add 0.5kg of paraffin" or "raise the temperature to 175℃". Based on the instruction type, it issues specific execution instructions to the automatic control module. At the same time, it coordinates the working sequence of each module through a timing generator, such as first collecting data → processing and judging → issuing instructions → executing control → collecting data again. Finally, it receives real-time execution status feedback from the automatic control module, such as "addition completed" or "temperature reached", and stores it.

[0031] Based on the above description of an automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesives, this invention also provides an automatic control method for monitoring the viscosity of chemically synthesized hot melt adhesives, such as... Figure 6 As shown, it includes the following steps: S1. Preset the viscosity standard threshold, reaction temperature range, shear rate range, and viscosity modifier addition amount calibration parameters for the chemically synthesized hot melt adhesive. Start the online viscosity monitoring module, data processing module, and automatic control module to complete the self-test and linkage debugging of each module. S2. Embed the online viscosity monitoring module into the hot melt adhesive synthesis reaction system to collect the apparent viscosity data, reaction temperature data and shear rate data of the hot melt adhesive in real time during the synthesis process, and transmit the collected raw data to the data processing module in real time. S3. The data processing module performs noise reduction and calibration on the received raw data to eliminate detection errors caused by high temperature environment and reaction disturbance. It plots real-time temperature-viscosity change curve by data fitting, compares the real-time viscosity data with the preset viscosity standard threshold, and determines whether the current viscosity is within the qualified range. If it is within the qualified range, the current synthesis process parameters are maintained. If it exceeds the qualified range, the corresponding control command is generated and transmitted to the control module. S4. After receiving the control command, the automatic control module starts the corresponding control unit. If the viscosity is higher than the preset threshold, the automatic control unit of the formula adds the preset amount of viscosity modifier, and at the same time the automatic control unit of the process parameters appropriately increases the reaction temperature and adjusts the mixing speed. If the viscosity is lower than the preset threshold, the automatic control unit of the formula reduces or stops adding viscosity modifier, and the automatic control unit of the process parameters appropriately decreases the reaction temperature and adjusts the mixing speed to achieve precise control of viscosity. S5. The online viscosity monitoring module continuously collects the viscosity data after adjustment, repeats steps S3-S4 until the viscosity of the hot melt adhesive returns to the qualified range. The control module records all parameters in this adjustment process, and combines them with historical adjustment data to automatically optimize the response speed and adjustment range of subsequent adjustment parameters, so as to achieve adaptive optimization of viscosity monitoring and adjustment.

[0032] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An automatic viscosity monitoring system for chemical synthesis of hot melt adhesives, characterized by, include: An online viscosity monitoring module that can be directly embedded in the hot melt adhesive synthesis reaction system is used to collect the apparent viscosity data, reaction temperature data and shear rate data of the hot melt adhesive in real time during the synthesis process; The data processing module is used to receive real-time data collected by the online viscosity monitoring module, perform noise reduction, calibration and fitting processing on the data, plot the real-time temperature and viscosity change curve, compare it with the preset hot melt adhesive viscosity standard threshold, determine whether the current hot melt adhesive viscosity meets the process requirements, and generate corresponding control instructions if it exceeds the threshold. The automatic control module includes an automatic formulation control unit for accurately metering and adding viscosity modifiers, and an automatic process parameter control unit for automatically adjusting the mixing speed, reaction temperature and isothermal time during the synthesis process, in response to control commands generated by the data processing module. The control module coordinates the collaborative work of the online viscosity monitoring module, data processing module, and automatic control module, stores real-time monitoring data, control parameters, and historical data, and performs closed-loop control of viscosity monitoring and regulation.

2. The automatic viscosity monitoring and regulating system for chemical synthesis of hot melt adhesive according to claim 1, characterized in that: The online viscosity monitoring module adopts a flange-sealed embedded structure to be embedded in the hot melt adhesive synthesis reaction system, thereby achieving integration with the hot melt adhesive synthesis reaction system.

3. The automatic viscosity monitoring and regulating system for chemical synthesis of hot melt adhesive according to claim 2, characterized in that: The online viscosity monitoring module includes a cone-plate rheological sensor, a temperature sensor, a shear rate detection unit, a signal processing unit, and a data transmission unit. The cone-plate probe of the cone-plate rheological sensor is sealed and fixed to the reaction vessel through a fluororubber seal. The probe of the temperature sensor is embedded in parallel with the cone-plate probe of the cone-plate rheological sensor, both passing through the fluororubber seal. The signal output terminals of the cone-plate rheological sensor, the temperature sensor, and the shear rate detection unit are all connected to the input terminal of the signal processing unit. The signal output terminal of the signal processing unit is connected to the signal input terminal of the data transmission unit. The data transmission unit establishes communication with the data processing module via wired or wireless means.

4. The automatic viscosity monitoring and regulating system for chemical synthesis of hot melt adhesive according to claim 1, characterized in that: The data processing module includes a noise reduction processing unit for eliminating interference signals in the original data, a calibration processing unit for correcting systematic errors in the detection data, a data fitting unit for fitting the temperature-viscosity relationship curve, a curve plotting unit for generating real-time temperature-viscosity change curves, a threshold comparison unit for determining whether the viscosity meets the process requirements, and an instruction generation unit for generating corresponding control commands. The noise reduction processing unit, calibration processing unit, data fitting unit, curve plotting unit, threshold comparison unit, and instruction generation unit are connected in sequence.

5. The automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesive according to claim 4, characterized in that: The process by which the curve plotting unit generates real-time temperature and viscosity change curves is as follows: A1. Sort the calibrated temperature and the fitted viscosity by timestamp to ensure data time sequence consistency; A2. Set the horizontal axis to temperature and the vertical axis to viscosity, and map each timestamp to a point on the coordinate plane. A3. Linear interpolation is used to connect adjacent data points to form a real-time temperature and viscosity change curve; A4. Receive new data every 50ms, update the curve data points, and realize dynamic curve refresh.

6. The automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesive according to claim 5, characterized in that: The threshold comparison unit obtains the current fitted real-time viscosity value and compares it with the preset viscosity standard threshold range. When the real-time viscosity value is within the viscosity standard threshold range, a qualified signal is output to maintain the current process parameters. When the real-time viscosity value is greater than the maximum value of the viscosity standard threshold range, a viscosity too high signal is output to trigger a viscosity reduction control command. When the real-time viscosity value is less than the minimum value of the viscosity standard threshold range, a viscosity too low signal is output to trigger a viscosity increase control command. Finally, the judgment result and the corresponding control command are transmitted to the control module.

7. The automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesive according to claim 1, characterized in that: The automatic formulation control unit includes: a corrosion-resistant storage tank for storing viscosity modifiers, and a liquid level sensor is installed inside the corrosion-resistant storage tank; A metering unit for precisely metering the amount of regulator added includes a plunger metering pump and a flow sensor installed on the plunger metering pump line; The delivery pipeline is used to transport the regulator to the reaction system, and the metering pump outlet is connected to the delivery pipeline; The control unit used to adjust the addition rate includes a servo controller and a PID control module; A valve unit for controlling the on / off state of a pipeline includes an electromagnetic shut-off valve. The outlet of the corrosion-resistant storage tank is connected to the electromagnetic shut-off valve via a flange, and the outlet of the electromagnetic shut-off valve is connected to the inlet of a plunger metering pump. The mixing unit includes a static mixer installed at the addition port, the end of the delivery pipeline is connected to the static mixer, and the outlet of the static mixer is embedded inside the reactor. The signal output terminals of the level sensor and flow sensor are connected to the signal input terminal of the control unit; the control output terminal of the control unit is connected to the servo motor of the plunger metering pump and the coil of the electromagnetic shut-off valve.

8. The automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesive according to claim 7, characterized in that: The automatic formulation control unit performs the following process for precise metering and addition of viscosity modifiers: B1. The servo controller receives control commands from the control module, which include the type of regulator, the target amount to be added, and the duration of addition. B2. The remaining amount of regulator in the corrosion-resistant storage tank is detected by the liquid level sensor. If it is lower than the minimum liquid level threshold, a replenishment alarm is issued; if it is sufficient, the solenoid shut-off valve is opened. B3. Calculate the required real-time addition rate based on the target addition amount and addition duration; B4. The flow sensor collects the actual added flow rate in real time, and the PID adjustment module compares the actual added flow rate with the target rate, and outputs a control signal to adjust the servo motor speed of the plunger metering pump. B5. The plunger metering pump outputs a corresponding displacement of regulator according to the rotation speed, ensuring that the actual addition amount is consistent with the target addition amount. B6. The regulator is delivered to the static mixer via the delivery pipeline and quickly mixed with the hot melt adhesive in the reactor. When the cumulative addition reaches the target addition amount, the electromagnetic shut-off valve and the plunger metering pump are closed, and a signal indicating that the addition is complete is sent back to the control module.

9. The automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesive according to claim 1, characterized in that: The automatic process parameter control unit includes: a temperature control subunit for adjusting the temperature of the reaction system, including a temperature controller, an electric heating element and a cooling coil. The cooling coil is equipped with a solenoid valve for controlling the flow of coolant. The temperature controller is electrically connected to the solenoid valve on the electric heating element and the cooling coil. A speed control subunit for controlling the speed of the mixing rotor, including a frequency converter and a three-phase asynchronous motor; The isothermal time control subunit, which controls the duration of isothermal ripening, includes a logic controller and a timer; The feedback sensing unit, used for real-time feedback of actual process parameters, mainly consists of a PT100 temperature sensor and a speed sensor. An actuator unit used to execute temperature and speed control commands includes a contactor, a relay, and a regulating valve; Safety protection units used to prevent process parameters from exceeding safe ranges include alarm modules and emergency stop switches; The output of the frequency converter driver is connected to a three-phase asynchronous motor, which is connected to the mixing rotor of the reactor via a coupling. The electric heating tube is embedded in the reactor jacket, and the cooling coil is connected to an external cooling water pump. The signal outputs of the PT100 temperature sensor and speed sensor are connected to the signal inputs of each control subunit. The control outputs of each control subunit are connected to contactors and relays. The safety protection unit is linked with the temperature control subunit, speed control subunit, and constant temperature time control subunit. When an alarm is triggered, the power supply to the actuator is cut off via an emergency stop switch.

10. An automatic control method for monitoring the viscosity of chemically synthesized hot melt adhesives, using the automatic control system for monitoring the viscosity of chemically synthesized hot melt adhesives as described in any one of claims 1-9, characterized in that: Includes the following steps: S1. Preset the viscosity standard threshold, reaction temperature range, shear rate range, and viscosity modifier addition amount calibration parameters of the chemically synthesized hot melt adhesive, start the online viscosity monitoring module, data processing module, and automatic control module, and complete the self-test and linkage debugging of each module. S2. Embed the online viscosity monitoring module into the hot melt adhesive synthesis reaction system to collect the apparent viscosity data, reaction temperature data and shear rate data of the hot melt adhesive in real time during the synthesis process, and transmit them to the data processing module in an instant. S3. The data processing module performs noise reduction and calibration on the received raw data to eliminate detection errors caused by high temperature environment and reaction disturbance. It fits and plots the real-time temperature-viscosity change curve, compares it with the preset threshold to determine whether the viscosity is qualified. If it is qualified, the process parameters are maintained. If it is not qualified, the control command is generated and transmitted to the control module. S4. After receiving the control command, the control module drives the automatic control module to perform precise control. S5. The online viscosity monitoring module continuously collects the viscosity data after adjustment, repeats S3-S4 until the hot melt adhesive viscosity is qualified, and the control module records the adjustment parameters and combines them with historical data to automatically optimize the response speed and amplitude of subsequent adjustments, thus completing the adaptive optimization of viscosity monitoring and adjustment.

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