Nano rubber epoxy resin flexibilizer double-emulsion stirring preparation method

Abstract

The invention relates to the technical field of epoxy resin materials, and discloses a nano rubber epoxy resin flexibilizer double-emulsion stirring preparation method, which comprises: mixing an epoxy resin matrix, a liquid rubber component, a surfactant and a diluent to form a primary double-emulsion; the method comprises the following steps: acquiring a viscosity induction torque representing dispersion phase droplet breaking resistance in a stirring process, monitoring a torque change rate to judge a dispersion equilibrium state, triggering a rotating speed step factor to increase a stirring rotating speed according to the torque change rate, and realizing forced regulation and control on dispersion phase particle size distribution by increasing shear stress; overlapping an oscillation shear field and cooperating with reverse stirring to induce an interface anchoring component to be spread and implanted at a phase interface to construct a chemical anchoring layer. According to the method, viscosity drift caused by temperature rise is compensated through torque feedback, the shear energy level is maintained to be constant, and the consistency of nanophase particle size distribution is ensured; a chemical anchoring structure is formed by utilizing an oscillation shearing induced phase interface, an infiltration dead zone is eliminated, the two-phase bonding strength is enhanced, and the service reliability of the material is improved.

Description

A method for preparing a nano-rubber epoxy resin toughening agent by stirring a double emulsion Technical Field

[0001] This invention belongs to the field of epoxy resin material technology, and particularly relates to a method for preparing a nano-rubber epoxy resin toughening agent by stirring a double emulsion. Background Technology

[0002] Currently, epoxy resin materials generally possess high mechanical strength and excellent chemical stability. To address the inherent brittleness of epoxy resins, constructing a dual-emulsion system using a nano-rubber phase to improve toughness is a common modification approach in industry. In the preparation process, high-speed shear stirring devices are typically used to disperse the nano-rubber phase within the epoxy resin matrix. However, as applications evolve towards heavy-duty and long-term service, the industry demands higher requirements for the dispersion precision and interfacial bonding strength of the nano-phase. Applying existing technologies to high-viscosity epoxy resin systems may lead to issues arising from rheological properties. Due to the inherent limitations of epoxy resin matrix, it exhibits non-Newtonian fluid characteristics at room temperature or under preheating conditions. This results in random and discontinuous transmission of mixed energy within the system. Under these conditions, the shear stress field experienced by fluid micro-elements moving within the stirred tank is randomly distributed, making it difficult to precisely guide the droplet deformation process. To overcome viscous resistance and achieve nanoscale fragmentation, the traditional linear logic of increasing driving power often leads to the conversion of mechanical work into internal energy, resulting in viscous dissipation. This temperature rise can easily induce mechanical thermal degradation of epoxy molecular chains, and viscosity fluctuations can also disrupt the stable transmission of shear force.

[0003] Furthermore, due to the lack of effective management of the dynamic state during energy unloading, the discrete nano-rubber micro-elements have high surface potential energy and are prone to thermodynamic re-aggregation when stirring stops, leading to the collapse of the toughening agent's microstructure. This severely restricts the long-term performance stability of the material. Although the industry has attempted to use ultrasonic cavitation or high-pressure homogenization, the high energy consumption and poor processing continuity of equipment in large-scale, high-viscosity industrial batching make it difficult to reverse the uncertainty of microstructure evolution caused by random stirring. In addition to hardware improvements, the exploration of process logic is also lagging behind. For example, Chinese invention patent with publication number CN120535906A... The application discloses a method for preparing a pre-dispersion liquid of active nano-silicone rubber core-shell particles. This technology focuses on constructing a multi-layer core-shell structure and drying it into powder, attempting to improve the initial dispersion state of the nano-phase at the chemical level. However, in actual stirring, the static chemical pre-processing path cannot sense the resistance fluctuations of the material caused by the non-Newtonian fluid characteristics in real time, making it difficult to perform energy gradient compensation for the temperature rise caused by viscous dissipation. Due to the lack of physical feedback on fluid deformation resistance, the system cannot control the shear energy level at each breakage equilibrium point, ultimately resulting in low dispersion efficiency and poor parameter consistency. Furthermore, it cannot eliminate the static rebound at the moment of stress unloading, making the nano-phase prone to secondary agglomeration.

[0004] Therefore, how to construct a nonlinear gradient stress field to forcefully constrain the plastic deformation process of fluid micro-elements in the hybrid system, eliminate the imbalance of nanophase distribution and static rebound while ensuring the integrity of epoxy resin molecular structure, and ensure the consistency of the preparation method of nano-rubber epoxy resin toughening agent by stirring in engineering implementation, has become the technical problem to be solved by this invention. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A method for preparing a nano-rubber epoxy resin toughening agent dual emulsion by stirring, comprising the following steps: Step S1, mixing epoxy resin matrix, liquid rubber component, surfactant and diluent uniformly to form a primary dual emulsion system in which a continuous phase and a dispersed phase coexist; the diluent is at least one volatile organic solvent selected from acetone, butanone, ethyl acetate, toluene or xylene; Step S2, placing the primary dual emulsion system in a stirring unit to perform a controlled stirring sequence, during the execution of the controlled stirring sequence, acquiring the viscosity-sensing torque value of the stirring unit, and extracting the viscosity-sensing torque increment characterizing the droplet breakage resistance of the dispersed phase from the viscosity-sensing torque value; Step S3, monitoring the rate of change of the viscosity-sensing torque increment over time, and when the rate of change is lower than a preset rate of change threshold, determining that the primary dual emulsion... In step S4, after step S3, an oscillating shear field with a frequency of 50 Hz to 200 Hz is superimposed on the primary dual emulsion system, and a reverse stirring operation with alternating directions is performed to induce the interface anchoring component to spread and implant at the interface between the dispersed phase droplets and the epoxy resin matrix to construct a chemical anchoring layer and obtain a nano-rubber epoxy resin toughening agent. The interface anchoring component is a polyetheramine modified adduct with matrix-loving polyether segments and active terminal epoxy groups, with a number average molecular weight of 2000 to 5000 and a terminal epoxy group content of 1.5 to 2.8 mol / kg.

[0006] Preferably, in step S3, the change rate threshold is 0.05 to 0.12, and the value of the rotation speed step factor is calibrated based on the real-time temperature of the primary dual emulsion system; when the real-time temperature increases and the viscosity of the system decreases, the value of the rotation speed step factor is increased to compensate for the decrease in shear energy level, so that the energy intake density is maintained within the preset range throughout the controlled stirring sequence.

[0007] Preferably, the shear stress intensity τ n Following a gradient distribution that satisfies the rheological properties of the fluid, its calculation method satisfies the following formula: τ n =τ base ·(1+λ i ) n-1 , where τ n τ is the shear stress intensity during the nth stage of stirring. base Based on the shear stress intensity, λ i is the speed step factor, and n is the stirring stage number.

[0008] Preferably, in step S4, the amplitude of the oscillating shear field is 0.1 mm to 0.5 mm, and the cycle of the reverse stirring operation is synchronized with the pulse cycle of the stirring speed, thereby using the alternating shear force field to lock the nanomorphic structure after breakage.

[0009] Preferably, in step S1, the epoxy resin matrix is ​​selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, multifunctional phenolic epoxy resin, hydrogenated bisphenol A type epoxy resin, or glycidyl ester type epoxy resin.

[0010] Preferably, in step S1, the liquid rubber component is selected from carboxyl-terminated liquid nitrile rubber, hydroxyl-terminated liquid nitrile rubber, amino-terminated liquid nitrile rubber, or vinyl-terminated liquid nitrile rubber, and the mass percentage of acrylonitrile in the liquid rubber component is 10% to 30%.

[0011] Preferably, in step S1, the mass ratio of epoxy resin matrix to liquid rubber component is 70:30 to 90:10, and the mass fraction of surfactant in primary dual emulsion system is 1% to 5%.

[0012] Preferably, in step S4, the interface anchoring component spreads on the surface of the dispersed phase droplets by oscillating shear field, so that the average particle size of the final formed nano-rubber phase in the epoxy resin matrix is ​​50 nm to 200 nm, and the particle size distribution index (PDI) is less than 0.15.

[0013] Preferably, after step S4, a devolatilization step is further included to remove the diluent, so that the volatile matter mass fraction in the nano-rubber epoxy resin toughening agent is less than 0.5%.

[0014] Preferably, in step S3, the triggering of the speed step factor is controlled by the real-time correlation curve between the viscosity-induced torque increment and the output current of the stirring unit. The torque fluctuation caused by the non-Newtonian fluid characteristics of the primary dual emulsion system is identified and eliminated through the correlation curve to ensure the determinism of the crushing path.

[0015] Compared with existing technologies, the present invention's method for preparing a nano-rubber epoxy resin toughening agent dual emulsion by stirring has the following advantages: 1. In the preparation of the nano-rubber epoxy resin toughening agent dual emulsion by stirring, through the synergistic effect of multi-level continuous stress pulse sequences and dynamic relaxation windows, the present invention solves the technical defect of uncontrollable nanophase dispersion process of epoxy resin matrix under high viscosity conditions. By adopting an arrangement in which the stress step factor increases with the processing stage, it can accurately match the nonlinear response requirements of epoxy resin molecular chains to shear field strength during the crushing process, so that the mixed system is in an effective plastic deformation range in each processing pass. After stress relaxation treatment, the mixed system obtains a buffer period for conformational rearrangement after experiencing high-energy shear, reducing the tendency of nano-rubber micro-elements to generate thermodynamic re-aggregation due to excessive surface potential energy. Thus, while maintaining the structural integrity of the epoxy resin matrix, a dual emulsion system with narrow particle size distribution and stable spatial dispersion is obtained.

[0016] 2. Based on the dynamic correction mechanism of the stress step factor executed by the high-frequency characteristic component of the driving torque, and based on the closed-loop adjustment capability of the preparation process for the fluctuation of material rheological properties, the deformation resistance state inside the fluid is inverted by the electrical signal characteristics fed back by the driving unit. This effectively eliminates the interference of viscosity fluctuations of different batches of epoxy resin raw materials on the consistency of energy intake. This real-time calibration path based on physical signal feedback enables the system to automatically match the optimal shear work density according to the evolution law of the dynamic viscosity of the system. This avoids the matrix thermal degradation or ineffective breakage of nanophase induced by stress step mismatch in traditional preparation processes, and ensures the stability of toughening agent quality in large-scale industrial production.

[0017] 3. The interface finishing step constructs a high-strength chemical anchoring layer between the nano-rubber phase and the epoxy resin matrix by superimposing a micro-amplitude oscillating field and periodic reverse shearing action. By utilizing a low-intensity and alternating shear force field, the interface anchoring components can be induced to perform isotropic spreading and implantation at the phase interface, eliminating the interface wetting dead zone caused by rapid fragmentation. This energy management strategy, which simulates a precision smoothing process, not only locks the nano-morphology after fragmentation but also improves the bonding strength between the rubber phase and the resin matrix. This results in the final cured product having better fatigue peeling resistance under alternating loads, achieving simultaneous enhancement of material dispersion accuracy and service reliability. Attached Figure Description

[0018] Figure 1 is a flowchart of the preparation process and feedback control of the nano-rubber epoxy resin toughening agent double emulsion stirring according to the present invention; Figure 2 is a schematic diagram of the logical architecture of the stirring preparation system with adaptive closed-loop control according to the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] This invention provides a method for preparing a nano-rubber epoxy resin toughening agent through a two-emulsion stirring process. The method comprises four stages: primary two-emulsion system construction, controlled stirring sequence execution, real-time viscosity feedback compensation, and interfacial energy gradient shaping. Its core lies in utilizing the physical signal characteristics fed back from the stirring drive unit to construct a nonlinear gradient stress field simulating the continuous rolling process of metals, thereby forcibly constraining the plastic deformation process of fluid micro-elements. In the primary two-emulsion system construction stage, the epoxy resin matrix, liquid rubber component, surfactant, and diluent are mixed according to a preset ratio. The diluent mentioned in this invention specifically refers to a non-reactive diluent (i.e., a volatile organic solvent) with low boiling point characteristics. The selection of components such as acetone or butanone is based on the fact that they can significantly reduce the volatile rubber toughening agent's viscosity. The viscosity mismatch between the epoxy resin matrix and the liquid rubber component is minimized, and its volatilization parameters are highly compatible with the devolatilization process after step S4, ensuring that the volatile matter mass fraction in the final product is less than 0.5%, thus avoiding negative impacts on the mechanical strength of the cured product. The epoxy resin matrix is ​​selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, multifunctional phenolic epoxy resin, hydrogenated bisphenol A type epoxy resin, or glycidyl ester type epoxy resin. The liquid rubber component is selected from carboxyl-terminated liquid nitrile rubber, hydroxyl-terminated liquid nitrile rubber, amino-terminated liquid nitrile rubber, or vinyl-terminated liquid nitrile rubber, wherein the mass percentage of acrylonitrile is 10% to 30%. The mass ratio of the epoxy resin matrix to the liquid rubber component is 70:30 to 90:10. The surfactant has a mass fraction of 1% to 5% in the system. The mixing process is carried out in a stirred tank. Preliminary mechanical mixing allows the dispersed phase to enter the continuous phase, forming a coexisting primary double emulsion system, providing the initial material state for subsequent stress field processing. The interface anchoring component is a polyetheramine modified adduct with terminal epoxy groups, a number average molecular weight of 2000 to 5000, and a terminal epoxy group content of 1.5 to 2.8 mol / kg. The interface anchoring component is added together with the surfactant during initial mixing. Utilizing the affinity between the polyether segments and the epoxy resin matrix, as well as the chemical reaction activity between the terminal epoxy groups and the carboxyl or amino functional groups of the liquid rubber component, step S4, alternating shear induces the interface anchoring component to perform isotropic spreading and implantation at the phase interface. A chemical anchoring layer with a thickness of 10 nm to 30 nm is constructed on the surface of a nano-rubber phase. The thickness of the anchoring layer is controlled by setting the mass fraction of the interface anchoring component in the primary two-emulsion system to 0.5% to 2.0%. The interface anchoring component of this invention is chemically a polyetheramine modified adduct with terminal epoxy groups. To ensure its precise migration and anchoring ability in complex high-viscosity epoxy resin systems, the number average molecular weight of this component is limited to 2000 to 5000, and its terminal epoxy group content is precisely controlled to 1.5 to 2.8 mol / kg. In the preparation process, this component is added together with the surfactant in the initial mixing stage of step S1, and its mass fraction in the primary two-emulsion system is 0.5% to 2.0%.The technical logic behind this 0% solution lies in the fact that the molecular structure of this component contains polyether segments with strong affinity and terminal epoxy groups with high chemical reactivity. The polyether segments are responsible for physical entanglement and compatibility with the epoxy resin matrix, while the terminal epoxy groups can chemically graft with active functional groups (such as carboxyl or amino groups) in the liquid rubber component. In the interface finishing operation of step S4, the kinetic energy provided by the superimposed oscillating shear field induces the component to overcome the steric hindrance at the phase interface, achieving isotropic spreading and implantation on the surface of the nanodroplets. Finally, a high-strength chemical anchoring layer with a thickness of 10nm to 30nm is constructed on the surface of the nano-rubber phase. This structure not only fundamentally locks the broken nanomorphology and prevents thermodynamic repolymerization after the shear force is removed, but also eliminates the wetting dead zone through interfacial bridging, enabling the cured material to have excellent fatigue peeling resistance and energy dissipation efficiency when subjected to alternating loads.

[0021] In the construction of the primary dual-emulsion system, the mass fraction of the diluent is limited to an optimal working window of 5% to 15%. This setting is based on balancing the initial processing viscosity of the system with the mechanical integrity of the final cured product. When the mass fraction of the diluent is below 5%, the viscosity mismatch between the high-viscosity epoxy resin matrix and the liquid rubber component is too high, leading to an excessively high basic shear stress intensity τ output by the stirring unit. base The initial deformation resistance of the dispersed phase droplets is difficult to overcome, leading to large-sized phase segregation in the primary dual emulsion system. When the mass fraction of the diluent exceeds 15%, excessive solvent molecules cause a decrease in the crosslinking density between epoxy resin molecular chains, and micropore defects are easily formed during subsequent devolatilization, resulting in a decrease in the tensile strength of the material of more than 20%. By controlling the amount of diluent within a certain range, the system ensures that the mixed system has suitable rheological responsiveness, enabling the viscosity-sensing torque increment to sensitively capture the weak energy fluctuations in the droplet breakup process, providing a high-quality material prerequisite for the precise application of subsequent stress pulse chains. During the execution of the controlled stirring sequence, the system acquires the viscosity-sensing torque value of the stirring unit and extracts the viscosity-sensing torque increment that characterizes the resistance to the breakup of the dispersed phase droplets. Due to the non-Newtonian fluid characteristics of the epoxy resin system, the shear stress required for its droplet breakup process increases as the particle size decreases. The system continuously monitors the rate of change k of the viscosity-sensing torque increment over time. When the rate of change k is lower than the preset rate of change threshold, it is determined that the dispersed phase droplets have reached the dispersion equilibrium state at the current stirring speed, at which point the preset speed step factor λ is triggered. iThe threshold for the rate of change is 0.05 to 0.12. In the actual implementation of this process, the dynamic increase in system temperature causes drastic fluctuations in the rheological properties of the nano-rubber epoxy resin matrix. Studies have found that limiting the rate of change threshold to between 0.05 and 0.12 is based on a balance between the response hysteresis of the servo control system and the stability of energy density. When the rate of change is below 0.05, the viscosity fluctuations exhibited by the system are often transient disturbances in a heterogeneous flow field. If speed compensation is triggered at this time, the excessive sensitivity of the control system will cause frequency oscillations in the mechanical structure, which will instead damage the system. The continuity of the microscopic shear field is disrupted. Once the rate of change exceeds 0.12, if energy level compensation is not performed in time using a speed step factor, the effective shear torque of the system will rapidly drop below the nanoparticle exfoliation energy level, causing the dispersed rubber particles to undergo uncontrolled secondary agglomeration under interfacial tension. Experiments show that by calibrating the speed step factor with real-time temperature, a closed-loop compensation mechanism of thermo-rheological-kinetic energy is essentially constructed, ensuring that the energy intake density throughout the controlled stirring process remains above the critical dispersion threshold. After triggering, the shear stress intensity τ is increased by increasing the stirring speed. n To increase the shear energy level and enforce control over the droplet size distribution; shear stress intensity τ n Follow the formula as follows: τ n =τ base ·(1+λ i ) n-1 , where τ n τ is the shear stress intensity during the nth stage of stirring, in Pa. base λ is the basic shear stress intensity, measured in Pa. i τ is the rotational speed step factor, ranging from 0.12 to 0.38; n is the stirring stage number; and τ is the shear stress intensity. n Following a gradient distribution that satisfies the rheological properties of the fluid, its calculation method satisfies the following formula: τ n =τ base ·(1+λ i ) n-1 Where the speed step factor λ i The numerical range is limited to between 0.12 and 0.38; the design logic of this formula lies in matching the exponentially increasing Laplace pressure (i.e., the internal deformation resistance of the droplet) of the non-Newtonian fluid during the particle size reduction process with an exponentially increasing stress field, ensuring that the shear energy level generated by each stage of stirring can break through the plastic fracture threshold of the droplet, thereby achieving forced and precise control of the nanophase particle size distribution; in this invention, the basic shear stress intensity τ base The initial energy threshold is determined based on the initial rheological parameters of the material to be processed and the kinetic characteristics of the stirring unit. Specifically, its calculation method satisfies the formula: τ base =η ini ·γini , where η ini γ is the initial dynamic viscosity of the epoxy resin matrix at 25°C. ini To determine the initial shear rate for the mixing unit when executing a controlled mixing sequence, the system needs to perform an initial benchmark calibration procedure before actual engineering applications: The mixing motor is driven to run at a constant speed of 300 rpm, and the inherent torque signal generated by the no-load current and mechanical impedance is collected in real time. An inherent mechanical impedance mapping table is then established. By subtracting the mechanical impedance from this mapping table from the real-time detected initial total torque, the τ, which characterizes the material's true resistance to plastic deformation, can be accurately determined. base This ensures that the initial energy density of the subsequent stress pulse chain is physically matched with the initial bite threshold of the fluid micro-element.

[0022] The viscosity-sensing torque increment is obtained through a pre-calibration program of the stirring drive unit. Before adding the liquid rubber component, the driving stirring motor performs a speed scan on the epoxy resin matrix at 25℃ to 80℃, records the no-load current at different frequencies and temperatures, converts it into torque values, and establishes an intrinsic mechanical impedance mapping table M. loss During the controlled stirring sequence operation in step S2, the control unit collects the total output torque M of the motor. total According to the formula ΔM=M total -M loss The viscosity-induced torque increment ΔM, which characterizes the droplet breakup resistance, is determined. ΔM is the viscosity-induced torque increment, and M is the value of M. total M represents the total output torque of the motor. loss To address the inherent mechanical impedance at the current frequency and temperature, the extraction of the rheological background torque of the epoxy resin matrix is ​​achieved by pre-measuring the resistance characteristics of the pure epoxy resin matrix under different temperature and rotational speed gradients before initial mixing, and establishing a dynamic mapping matrix M. lossThe matrix (T,ω) is used to compensate for the matrix shear thinning behavior caused by the system temperature rise, ensuring that the extracted viscosity-sensing torque increment ΔM only reflects the effective deformation resistance of the dispersed phase droplets when subjected to shear breakage, thus eliminating the nonlinear interference of the non-Newtonian fluid matrix. When the rate of change of viscosity-sensing torque increment with time k is less than 0.05 for 30 consecutive sampling periods, the dispersed phase droplets are determined to have reached the dispersion equilibrium state. In order to accurately separate and extract the viscosity-sensing torque increment ΔM characterizing the resistance to breakage of dispersed phase droplets, the viscosity-sensing torque in this embodiment is not a simple instantaneous torque difference, but a dynamic increment relative to the matrix rheological reference. Specifically, due to the non-Newtonian fluid characteristics of the epoxy resin matrix and liquid rubber component after mixing, the total torque fluctuation of the system is not a linear superposition of mechanical friction and fluid resistance. In the calibration logic of this method, the no-load state is strictly defined as: including the inherent mechanical friction loss of the stirring mechanism, and the basic viscous resistance generated by the epoxy resin matrix with a stable flow field established at the current real-time temperature and speed. Considering the nonlinear load drift caused by the concentration gradient and polarity interaction after the material is added, the mapping table M loss A rheological coupling correction factor η based on shear rate was introduced during the establishment process. c During controlled mixing, the torque increment ΔM extracted by the system refers to the real-time mapping at the drive end of the effective shear work consumed to overcome Laplace pressure during the evolution of the dispersed phase (liquid rubber) from large-scale phase regions to nanoscale droplets after removing the above-mentioned system no-load baseline. This increment can accurately capture the torque plateau point generated when the dispersed phase reaches dispersion equilibrium due to the micro-element deformation rate approaching zero. This effectively eliminates the interference of unstable flow in the initial mixing stage, matrix viscosity dilution caused by temperature rise, and non-Newtonian fluid shear thinning behavior on the determination of crushing dynamics, ensuring the speed step factor λ. i The triggering logic is unique and deterministic.

[0023] To address the temperature rise caused by viscous dissipation during processing, the system implements a real-time feedback compensation process. Temperature rise leads to a decrease in the dynamic viscosity of the epoxy resin system, thereby diluting the effective shear energy level. The system continuously monitors the temperature of the primary dual-emulsion system and adjusts the rotational speed step factor λ based on temperature fluctuations. i The values ​​are calibrated; the specific compensation strategy is as follows: taking 25℃ as the reference origin, when the value fed back by the real-time temperature sensor increases by 1℃, the control program automatically increments the speed step factor by 0.0067 from the initial value, in order to compensate for the decrease in shear energy dissipation caused by the decrease in system viscosity by increasing the output frequency of the stirring motor, ensuring that the deviation of the actual input shear energy density is less than 5%. When the temperature increases and the viscosity decreases, the system increases the speed step factor λ. iThe value of this step factor λ is used to compensate for the decrease in shear energy level, ensuring that the energy intake density remains within a preset range throughout the controlled stirring sequence, thus guaranteeing the determinism of the breakup path; this step factor λ is used to compensate for the decrease in shear energy level. i The triggering of step S3 is controlled by the real-time correlation curve between the viscosity-sensing torque increment and the output current of the stirring unit, which is used to eliminate torque fluctuations caused by non-Newtonian fluid characteristics. The triggering of step S3 is controlled by the composite logic of rate of change determination and correlation curve verification. The rate of change k being lower than the threshold is the main triggering condition for determining the dispersed equilibrium. The real-time correlation curve is used as a logic gate to filter interference. When the torque fluctuation originates from the actual droplet breaking resistance, the torque increment and the output current signal exhibit highly linear in-phase evolution characteristics. If the fluctuation is caused by the nonlinear rheological characteristics of non-Newtonian fluid, the two exhibit obvious phase lag. The system uses discrete Fourier transform to extract the characteristic components in the frequency band from 10Hz to 50Hz, and eliminates rheological noise by identifying the linearity deviation of the correlation curve to ensure the determinism of the breaking path.

[0024] After the controlled stirring sequence is completed, the system superimposes an oscillating shear field with a frequency of 50Hz to 200Hz, and performs a reverse stirring operation with alternating directions. The amplitude of the oscillating shear field is 0.1mm to 0.5mm, and the period of the reverse stirring operation is synchronized with the pulse period of the stirring speed. The alternating shear force field locks the broken nano-morphology. In step S4, a piezoelectric ceramic transducer array integrated at the bottom of the stirring shaft generates an oscillating shear field. The transducer receives a sinusoidal electrical signal from the high-frequency drive power supply and converts the electrical energy into mechanical longitudinal vibration with a frequency of 50Hz to 200Hz and an amplitude of 0.1mm to 0.5mm. The vibration is superimposed on the rotating shear field of the stirring blade to generate a high-frequency micro-amplitude pulse pressure pointing towards the phase interface, inducing the molecular chains of the interface anchored components to overcome the steric hindrance and diffuse to the surface of the nanodroplets. This is combined with the reverse stirring operation with the alternating direction and frequency synchronized with the pulse period of the stirring speed. The process involves instantaneous stress removal to lock in the nano-morphology, resulting in an average particle size of the nano-rubber phase converging to 50 nm to 200 nm with a particle size distribution index (PDI) below 0.15. This PDI process induces the interfacial anchoring components to spread and implant at the interface between the dispersed phase droplets and the epoxy resin matrix, constructing a chemical anchoring layer and eliminating wetting dead zones. The final nano-rubber phase in the epoxy resin matrix has an average particle size of 50 nm to 200 nm and a PDI below 0.15. After completing the interfacial energy gradient shaping, a devolatilization step is included to remove the diluent, ensuring that the volatile matter mass fraction in the nano-rubber epoxy resin toughening agent is below 0.5%. The resulting toughening agent possesses a high-strength chemical anchoring structure between the rubber phase and the matrix, exhibiting fatigue-resistant peeling properties under alternating loads and improving the material's service reliability.

[0025] Example 1: In a scenario involving the preparation of 30% by mass of terminal carboxyl-terminated liquid nitrile rubber and 70% by mass of bisphenol A type epoxy resin, the initial particle size of the dispersed phase component in the high-viscosity matrix is ​​greater than 10 μm. Furthermore, the shear heat generated during stirring causes the system temperature to rise by 12°C within 15 minutes, resulting in a decrease in system viscosity and the formation of rubber phase particles with a particle size greater than 40 μm. The stirring unit acquires the viscosity-sensing torque increment by frequently sampling the motor current signal. When the rate of change of the viscosity-sensing torque increment over time, k, stabilizes at 0.08, it is determined that the droplet breakup has reached equilibrium at the 500 rpm energy level. The system adjusts the rotational speed step factor λ based on the collected temperature rise value. i Adjust, to λ i The value was changed from 0.20 to 0.28, so that the stirring speed of the next stage is based on the formula τ. n =τ base ·(1+λ i ) n-1 To determine the shear stress intensity, the rotation speed was increased to 820 rpm to maintain the shear stress intensity τ against the backdrop of decreasing viscosity. n Within the stress range that induces plastic fracture in the rubber phase, τ n τ represents the shear stress intensity during the nth stage of stirring, in Pa. base The basic shear stress intensity, in Pa, λ i is the speed step factor, and n is the stirring stage number.

[0026] After undergoing four stress step cycles, the system is superimposed with a 150Hz oscillating shear field to induce the interfacial anchoring components to spread at the phase interface. By synchronously cooperating the reverse stirring cycle and the rotation speed pulse cycle, the interfacial wetting dead zone is eliminated. The average particle size of the nano-rubber phase converges to 115nm and the particle size distribution index (PDI) is 0.12. The crack propagation resistance of the solidified material under 50J impact is increased by 45% compared with the normal process, achieving uniformity of nanophase particle size distribution and enhanced interfacial bonding strength.

[0027] Example 2: In a 50L reactor preparation scenario, the experimental subjects were bisphenol A type epoxy resin and carboxyl-terminated liquid nitrile rubber. The initial dynamic viscosity of the epoxy resin matrix at 25℃ was 12.5 Pa·s, and the mass fraction of the liquid rubber component was 20%. The experimental platform was equipped with a stirring drive unit with a torque measurement resolution of not less than 0.01 N·m and a signal sampling frequency of not less than 100 Hz, used to capture the physical fluctuations of the internal deformation resistance of the fluid in real time, and the temperature control accuracy was maintained within ±0.5℃. To address the 8.5℃ temperature rise of the system due to viscosity dissipation during stirring, random torque noise with a signal-to-noise ratio of 20 dB was actively superimposed on the experimental signal source to simulate the interference of the industrial environment on the measurement of viscosity-sensing torque value. The sampling period was set to balance the real-time performance of signal processing and the load of the computing unit, and its value was determined to be 10 ms according to the Nyquist sampling criterion to ensure the accuracy of extracting the rate of change k of viscosity-sensing torque increment over time.

[0028] The experimental design included the present invention sample group, control group 1, control group 2, and control group 3, wherein control group 1 removed the thermo-mechanical co-calibration step in the controlled stirring sequence, and control group 2 adjusted the rotational speed step factor λ. i The speed step factor λ was set to 0.45 for control group 3. i The value was set to 0.10. The parameters of both control groups 2 and 3 deviated from the range of 0.12 to 0.38. During the controlled stirring sequence, the stirring unit operated at an initial speed of 400 rpm. The system extracted droplet breakage resistance characteristics by monitoring the viscosity-sensing torque increment. When the rate of change k was detected to be 0.08, it was determined that the plastic work input of the current energy level was approaching equilibrium, triggering a speed step. In the sample group of this invention, the system adjusted λ based on the real-time collected system temperature of 42.5℃. i Dynamic compensation is performed, and this value is set to 0.25 to ensure that the next level of shear stress intensity τ n According to the formula τ n =τ base ·(1+λ i ) n-1 The resulting gain offsets the shear force dilution caused by the decrease in viscosity. For a comparison of specific experimental data, please refer to Table 1.

[0029] Table 1: Performance Test Data of Nano Rubber Epoxy Resin Toughening Agent

[0030] Analysis of the data in Table 1 shows that, due to the lack of stress step compensation, the effective shear force in control group 1 decreases with increasing temperature, resulting in a rubber phase with an average particle size of 358.4 nm and a wide distribution; when λ iWhen the shear force exceeds the upper limit of 0.38, as shown in control group 2, although the shear force increases, the high-intensity energy input induces thermal degradation of the epoxy resin molecular chains, leading to a sharp increase in system temperature to 15.2℃, causing the particle size distribution index (PDI) to deteriorate to 0.24; when λ i Below the lower limit of 0.12, as shown in control group 3, the shear stress increment is insufficient to overcome the droplet deformation resistance, resulting in the average particle size remaining at 850.3 nm. However, within the working window of 0.25, the sample of this invention achieves convergence of the nanophase at 118.2 nm through dynamic adaptation of stress field intensity and rheological properties, with a solidified impact strength of 42.5 kJ·m. -2 The experimental results confirmed that the synergistic effect of the parameters in the controlled stirring sequence constrained the deformation process of the fluid micro-element and ensured the evolution of the nanophase morphology under complex thermodynamic environment. After the interfacial energy gradient was stabilized, the preparation process carried out a devolatilization process under a pressure of 0.05 MPa to remove the residual diluent with a mass fraction of 2.5% in the system until its volatile mass fraction was less than 0.5%. The final obtained nano-rubber epoxy resin toughening agent has a chemical anchoring layer between the rubber phase and the matrix.

[0031] Example 3: This example, in conjunction with Figures 1 and 2, illustrates a method for preparing a nano-rubber epoxy resin toughening agent using a dual-emulsion stirring process. As shown in Figure 1, step S1 involves mixing the epoxy resin matrix, liquid rubber component, surfactant, and diluent to form a continuous and dispersed phase coexisting system through a primary dual-emulsion system. The process then proceeds to step S2, a controlled stirring sequence, where the system is placed in a stirring unit to perform shearing and apply basic shear stress. Simultaneously, viscosity-sensing torque is acquired, and the torque increment characterizing the droplet breakage resistance of the dispersed phase is extracted. During this process, the system performs logical judgments to monitor whether the rate of change is below a threshold. If the judgment result is yes, indicating that dispersion equilibrium has been reached, a speed step factor is triggered. By increasing the stirring speed and shear stress intensity, the particle size distribution is forcibly controlled. Feedback is sent to the stirring sequence via the dotted path. When the judgment result is no or the sequence is completed, step S4, interface finishing, is performed. An oscillating shear field with a frequency of 50Hz-200Hz is superimposed and combined with reverse stirring to induce the interface anchoring component to spread and implant at the phase interface to construct a chemical anchoring layer, ultimately yielding the nano-rubber epoxy resin toughening agent.

[0032] As shown in Figure 2, the upper left side is the power execution subsystem, which integrates a current / torque transformer and a variable frequency stirring motor. It receives speed commands and outputs resistance feedback signals to the core. The upper right side is the reaction environment subsystem, which includes a dual emulsion reactor and a high-sensitivity temperature probe for collecting and outputting temperature rise data. The adaptive process control core located in the center receives the above resistance feedback and temperature rise data, processes them using the internally integrated viscosity-torque analysis, speed step calculation, and thermodynamic error compensation modules, and sends speed commands to the power execution subsystem and oscillation frequency control signals to the interface micro-control subsystem located below, driving the oscillation shear generator to run, thereby forming a closed-loop control logic.

[0033] Example 4: In the preparation of a phenolic epoxy resin toughening system with a functional group density of 176 g / eq and an initial dynamic viscosity of 35.8 Pa·s at 25°C, the branched structure of the matrix molecules leads to nonlinear shear thinning behavior. Furthermore, the viscosity-temperature sensitivity coefficient in the temperature range of 60°C to 80°C is higher than that of bisphenol A epoxy resin. The shear heat generated during stirring causes a local temperature increase of 15°C within 8 minutes, resulting in fluctuations in effective shear force and causing thermodynamic agglomeration of the rubber phase in conventional processes. To establish the execution criteria in the controlled stirring sequence, this method performs dynamic frequency scanning on the epoxy resin matrix within a temperature field from 25°C to 100°C, extracting the storage modulus and loss modulus at different shear rates. Based on the scanning curves, the system determines the lower limit of the effective shear stress of the phenolic epoxy system in the initial stage of stirring, and accordingly sets the rotational speed step factor λ. i The initial value is set to 0.15.

[0034] During the preparation process, the stirring unit collects the real-time output torque signal of the drive motor, extracts the current fluctuation characteristics in the 10Hz to 50Hz frequency band using discrete Fourier transform, and converts it into viscosity-sensing torque increment. The judgment logic is as follows: when the rate of change k of the viscosity-sensing torque increment over time is maintained below 0.06 for 50 consecutive sampling periods, the system confirms that it is in a state of dispersion equilibrium. At this time, the system reads the instantaneous temperature value of 72.4℃ fed back by the platinum resistance sensor in the reactor, and adjusts λ according to the temperature sensitivity coefficient of the matrix. i Correction, λ i Adjusted to 0.32; this step reduces the shear stress intensity τ of the next stage of stirring. n Achieving physical compatibility with the real-time rheological resistance of the matrix, the total dissipated energy generated by each stage of stirring is maintained within the preset plastic work range, addressing the problem of energy loss during the temperature rise process of high-viscosity systems; shear stress intensity τ n The calculation formula is as follows: τ n =τ base ·(1+λ i ) n-1 , where τ nτ is the shear stress intensity during the nth stage of stirring, in Pa. base λ is the basic shear stress intensity, measured in Pa. i denoted as the rotational speed step factor; n is the stirring stage number; during the process of performing interface energy gradient shaping, a high-frequency micro-amplitude oscillating shear field of 180Hz is superimposed on the system, with its amplitude set to 0.15mm; this kinetic energy input induces the functional groups at the dispersed phase interface to couple with the matrix molecules, constructing a chemical anchoring layer with a thickness of 8nm to 15nm within the residence time; the average particle size of the nano-rubber phase in the finally obtained nano-rubber epoxy resin toughening agent converges to 85.2nm, and the particle size distribution index (PDI) is 0.09. The data comparison between the experimental group and the control group is shown in Table 2.

[0035] Table 2: Parameter Calibration and Performance Test Data of Phenolic Epoxy Toughening System

[0036] Analysis of data 2 shows that in control group A, the step factor was not adequately compensated for the viscosity dilution caused by temperature rise, resulting in insufficient shear force to overcome droplet deformation resistance, causing the particle size to remain at the micrometer level. Although control group B increased the energy input, the lack of precise control over the interfacial diffusion process led to secondary re-aggregation of the product during devolatilization. The experimental group, through the collaboration of parameter calibration and feedback compensation, achieved forced constraint on the deformation process of fluid micro-elements in the high-viscosity system. The dense chemical anchoring layer formed at the product cross-section hindered crack propagation and improved the mechanical strength of the composite material under extreme service conditions.

[0037] Example 5: In a batch preparation scenario of hydrogenated bisphenol A type epoxy resin with an initial viscosity of 18.2 Pa·s, the system initiates an initial benchmark calibration program before the controlled stirring sequence. The epoxy resin matrix is ​​driven to run at a constant speed of 300 rpm within a temperature range of 25°C to 60°C, and the benchmark load current and no-load output torque signals are acquired in real time. By performing discrete sampling on the acquired benchmark load current, the inherent mechanical impedance of the drive motor is calculated, and a real-time mapping model between the drive motor electrical signal and the fluid deformation resistance is established using a piecewise linear fitting method. By performing incremental loading tests on standard viscosity samples, the system calibrates the proportional conversion coefficient of the viscosity-induced torque increment, so that the time change rate k reflects the plastic power dissipation level of the dispersed phase droplets in a hardware environment. The basic shear stress intensity τ is calibrated online based on the initial flow resistance of the epoxy resin matrix. base This allows the initial energy density of the stress pulse chain to be physically matched with the initial bite threshold of the fluid element.

[0038] When the system encounters a carboxyl-terminated liquid nitrile rubber component with an acrylonitrile content of 25% and an initial viscosity that deviates by 15% from the baseline batch, the control unit performs a parameter fine-tuning process to adjust the output accuracy of the stress field. A platinum resistance sensor collects real-time temperature data inside the reactor, while the motor feedback loop captures high-frequency current components at a sampling frequency of 120Hz. By logically comparing the measured viscosity-sensing torque increment with a pre-stored intrinsic mechanical impedance benchmark, a three-point calibration test is performed to determine the speed step factor λ for this specific material. i The system acquires the real-time value of the torque signal; in the first step of the stirring speed change, the system captures the response delay of the torque signal to the speed change and corrects λ accordingly. i The gain compensation parameter is used to reduce the shear stress intensity τ of the next stage of stirring. n Following the formula τ n =τ base ·(1+λ i ) n-1 A defined evolutionary path, where τ n τ represents the shear stress intensity during the nth stage of stirring, in Pa. base The basic shear stress intensity, in Pa, λ i The rotational speed step factor is n, and the stirring stage is n. After the process is executed, the average particle size of the nano-rubber phase in the product converges to 110.5 nm and the particle size distribution index (PDI) is 0.10. At the same time, the synchronous effect of the oscillating shear field and the adaptive stirring sequence induces the formation of a uniformly distributed chemical anchoring layer at the phase interface.

[0039] Example 6: In a preparation system consisting of an anchor-type stirring paddle with a diameter of D and a reaction vessel with an inner diameter of 600 mm, the inherent frictional resistance of the drive chain and the random fluctuations caused by the radial runout of the bearings result in the extracted original torque signal containing more than 15% mechanical impedance components. This causes a detection offset in the viscosity-sensing torque increment, which reflects the resistance of the dispersed phase droplets to deformation, leading to a logical misjudgment when the system determines the physical state of the rate of change k, and triggering a speed step factor λ. i The triggering timing deviates from the preset processing path, and an impedance calibration process based on standard Newtonian fluid is executed. Under no-load conditions in the stirred tank, the stirring unit is driven to perform a stepped speed increase within the speed range of 100 rpm to 1000 rpm. Real-time acquisition of no-load current and torque feedback values ​​at each speed level is used to establish an inherent mechanical impedance mapping table. For determining the equilibrium state of droplet breakup, the system sets the sampling time window for viscosity-sensing torque increment to 30 seconds, and according to the formula τ... base =η ini ·γ ini Determine the initial energy level of the stress field, where τ base The basic shear stress intensity is expressed in Pa; η iniγ is the initial dynamic viscosity of the epoxy resin matrix at 25°C, expressed in Pa·s; ini Initial shear rate, in seconds. -1 .

[0040] In actual operation, the control unit subtracts the corresponding impedance value from the mapping table from the real-time acquired torque signal and monitors the sliding average value of the rate of change k over three consecutive sampling periods. When the k stabilizes within the preset threshold range of 0.05 to 0.12 and the signal ripple variance is less than 0.02, the next-level speed step factor λ is triggered. i By applying this standardized process and discretizing the sampling time window, the system reduces the impact of mechanical transmission errors on the criterion threshold, thus reducing the shear stress intensity τ at each rotational speed. n Controlled by the real-time rheological response of fluid micro-elements, the average particle size of the rubber phase in the obtained nano-rubber epoxy resin toughening agent remained within the range of 112.5 nm to 118.2 nm in independent production batches, and its particle size distribution index (PDI) remained stable at 0.11. The chemical anchoring layer formed in the product provided a stable interfacial stress transmission path during the deformation of the cured product. In the preparation scheme using carboxyl-terminated liquid nitrile rubber as the liquid rubber component, the interfacial anchoring component was selected from polyetheramine modified with epoxy group end caps, utilizing its amphiphilic structure at the phase interface. Chemical bridging is performed at the interface. During the superimposed oscillating shear field from 50Hz to 200Hz, the hydrophilic segment of the polyetheramine modifier undergoes hydrogen bonding association with the epoxy resin matrix, while its hydrophobic long carbon chain portion penetrates the interface layer of the dispersed phase droplet under the induction of the alternating force field and forms physical entanglement or chemical grafting with the rubber molecular chain. By monitoring the energy intake density of the interface energy gradient during the shaping stage, the system ensures that the anchoring reaction is completed before the droplet re-aggregation tendency occurs, so that the chemical anchoring layer finally formed on the surface of the nano rubber phase has a thickness gradient of more than 10nm.

[0041] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A method for preparing a nano-rubber epoxy resin toughening agent by stirring a double emulsion, characterized in that, Includes the following steps: Step S1: Mix the epoxy resin matrix, liquid rubber component, surfactant, and diluent evenly to form a primary dual-emulsion system in which the continuous phase and dispersed phase coexist. The diluent is at least one volatile organic solvent selected from acetone, butanone, ethyl acetate, toluene, or xylene. Step S2: Place the primary dual-emulsion system in a stirring unit and execute a controlled stirring sequence. During the controlled stirring sequence, obtain the viscosity-sensing torque value of the stirring unit and extract the viscosity-sensing torque increment, which characterizes the resistance to droplet breakage in the dispersed phase. Step S3: Monitor the rate of change of the viscosity-sensing torque increment over time. When the rate of change is lower than a preset threshold... When the value is reached, it is determined that the dispersed phase droplets in the primary dual emulsion system have reached the dispersion equilibrium state at the current stirring speed, triggering the preset speed step factor, and increasing the stirring speed based on the speed step factor to increase the shear stress intensity. By increasing the shear energy level, the particle size distribution of the dispersed phase droplets is forcibly controlled; in step S4, after step S3 is completed, an oscillating shear field with a frequency of 50Hz to 200Hz is superimposed in the primary dual emulsion system, and a reverse stirring operation with alternating directions is performed to induce the interface anchoring component to spread and implant at the phase interface between the dispersed phase droplets and the epoxy resin matrix to construct a chemical anchoring layer and obtain a nano-rubber epoxy resin toughening agent; The interface anchoring component is a polyetheramine modified adduct with terminal epoxy groups; The interface anchoring component is a polyetheramine modified adduct with matrix-loving polyether segments and active terminal epoxy groups, with a number average molecular weight of 2000 to 5000 and a terminal epoxy group content of 1.5 to 2.8 mol / kg.

2. The method for preparing a nano-rubber epoxy resin toughening agent by stirring a dual emulsion according to claim 1, characterized in that, In step S3, the rate of change threshold is 0.05 to 0.12, and the value of the rotational speed step factor is calibrated based on the real-time temperature of the primary dual emulsion system. When the real-time temperature increases and the system viscosity decreases, the value of the rotation speed step factor is increased to compensate for the decrease in shear energy level, so that the energy intake density is maintained within the preset range throughout the controlled stirring sequence.

3. The method for preparing a nano-rubber epoxy resin toughening agent by stirring a dual emulsion according to claim 1, characterized in that, Shear stress intensity τ n Following a gradient distribution that satisfies the rheological properties of the fluid, its calculation method satisfies the following formula: τ n =τ base ⋅(1+λ i ) n-1 , where τ n τ is the shear stress intensity during the nth stage of stirring. base Based on the shear stress intensity, λ i is the speed step factor, and n is the stirring stage number.

4. The method for preparing a nano-rubber epoxy resin toughening agent by stirring a dual emulsion according to claim 1, characterized in that, In step S4, the amplitude of the oscillating shear field is 0.1 mm to 0.5 mm, and the period of the reverse stirring operation is synchronized with the pulse period of the stirring speed, thereby using the alternating shear force field to lock the nanomorphic structure after breakage.

5. The method for preparing a nano-rubber epoxy resin toughening agent by stirring a dual emulsion according to claim 1, characterized in that, In step S1, the epoxy resin matrix is ​​selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, multifunctional phenolic epoxy resin, hydrogenated bisphenol A type epoxy resin, or glycidyl ester type epoxy resin.

6. The method for preparing a nano-rubber epoxy resin toughening agent by stirring a dual emulsion according to claim 1, characterized in that, In step S1, the liquid rubber component is selected from carboxyl-terminated liquid nitrile rubber, hydroxyl-terminated liquid nitrile rubber, amino-terminated liquid nitrile rubber, or vinyl-terminated liquid nitrile rubber, and the mass percentage of acrylonitrile in the liquid rubber component is 10% to 30%.

7. The method for preparing a nano-rubber epoxy resin toughening agent by stirring a dual emulsion according to claim 5, characterized in that, In step S1, the mass ratio of epoxy resin matrix to liquid rubber component is 70:30 to 90:10, and the mass fraction of surfactant in primary dual emulsion system is 1% to 5%.

8. The method for preparing a nano-rubber epoxy resin toughening agent by stirring a dual emulsion according to claim 1, characterized in that, In step S4, the interface anchoring component spreads on the surface of the dispersed phase droplets through oscillating shear field induction, so that the average particle size of the final formed nano-rubber phase in the epoxy resin matrix is ​​50 nm to 200 nm, and the particle size distribution index (PDI) is less than 0.

15.

9. The method for preparing a nano-rubber epoxy resin toughening agent by stirring a dual emulsion according to claim 1, characterized in that, After step S4, a devolatilization step is also included to remove the diluent, so that the volatile matter mass fraction in the nano-rubber epoxy resin toughening agent is less than 0.5%.

10. The method for preparing a nano-rubber epoxy resin toughening agent by stirring a dual emulsion according to claim 5, characterized in that, In step S3, the triggering of the speed step factor is controlled by the real-time correlation curve between the viscosity-induced torque increment and the output current of the stirring unit. The torque fluctuation caused by the non-Newtonian fluid characteristics of the primary dual emulsion system is identified and eliminated through the correlation curve.

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