Temperature-responsive emulsifier, preparation method, application and epoxy resin emulsifying equipment

Abstract

The invention belongs to the technical field of epoxy resin emulsification, and particularly relates to a temperature response type emulsifier, a preparation method, application and epoxy resin emulsification equipment. The preparation method of the temperature response type emulsifier comprises the following steps: (1) mixing a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with water, dissolving, and adjusting the pH value to obtain a pre-polymerized solution; (2) adding an N-isopropylacrylamide monomer and an initiator into the pre-polymerized solution under the protection of nitrogen, and heating for reaction to obtain a reaction solution; (3) adding a cross-linking agent into the reaction liquid for cross-linking modification to obtain a crude product; and (4) purifying the crude product obtained in the step (3) to obtain the temperature-responsive emulsifier. The temperature-responsive emulsifier provided by the invention is helpful for realizing regulation and control of the surface activity of the emulsifier, and breaks through the technical limitation of the traditional static emulsifier.

Description

Technical Field

[0001] This invention belongs to the field of epoxy resin emulsification technology, specifically relating to a temperature-responsive emulsifier, its preparation method, its application, and epoxy resin emulsification equipment. Background Technology

[0002] Currently, the preparation technology of waterborne epoxy emulsions faces multiple challenges. Traditional emulsification processes mainly rely on static surfactants, whose hydrophilic-lipophilic balance values ​​remain constant. These surfactants cannot adapt to dynamic changes in process parameters such as temperature and viscosity during emulsification, resulting in low emulsification efficiency and insufficient product stability. Especially under cold environmental conditions, the viscosity of epoxy resin increases dramatically (in low-temperature environments ranging from -20℃ to 0℃, the viscosity of oil-based epoxy resin can increase by 8-25 times, making effective dispersion difficult with traditional mechanical stirring). Traditional emulsification processes require large-scale heating of the entire reaction system, resulting in high energy consumption and difficulty in temperature control, often leading to resin degradation due to localized overheating.

[0003] Existing emulsifier technologies have significant limitations. Current emulsifiers are sensitive to pH and ionic strength, and are prone to hydrolysis at high temperatures, affecting the long-term stability of the emulsion. Furthermore, traditional polymeric emulsifiers have a wide molecular weight distribution and poor batch stability, making precise process control difficult. The effects of cold environments further exacerbate these technical challenges (at low temperatures, the surface activity of traditional emulsifiers decreases significantly, the critical micelle concentration increases, and emulsification efficiency drops sharply).

[0004] Existing emulsification equipment technology also has significant shortcomings. Traditional high-speed shearing equipment mainly relies on mechanical shearing force to achieve dispersion, resulting in low energy utilization efficiency and a tendency to generate localized high temperatures, leading to uneven product performance. While ultrasonic dispersion equipment has good dispersion effects, its processing capacity is limited when used alone, making it difficult to meet the needs of industrial production. Steam heating equipment lacks precise temperature control, easily causing overheating or uneven heating, affecting the stability of product quality.

[0005] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0006] The purpose of this invention is to provide a temperature-responsive emulsifier, its preparation method, its application, and an epoxy resin emulsification device, in order to help solve or improve the problem of achieving uniform dispersion of oily epoxy resins in water.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a temperature-responsive emulsifier, comprising the following steps: (1) mixing polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with water, dissolving it, and adjusting the pH to obtain a prepolymer solution; (2) adding N-isopropylacrylamide monomer and an initiator to the prepolymer solution under nitrogen protection, heating the solution to obtain a reaction solution; (3) adding a crosslinking agent to the reaction solution for crosslinking modification to obtain a crude product; (4) purifying the crude product obtained in step (3) to obtain the temperature-responsive emulsifier.

[0008] The present invention also provides a temperature-responsive emulsifier, which adopts the following technical solution: a temperature-responsive emulsifier is prepared by the method described above.

[0009] The present invention also provides an epoxy resin emulsion, which adopts the following technical solution: an epoxy resin emulsion, wherein the components of the epoxy resin emulsion include epoxy resin, temperature-responsive emulsifier as described above, and water.

[0010] This invention also provides a method for preparing an epoxy resin emulsion, which adopts the following technical solution: The method for preparing an epoxy resin emulsion as described above includes the following steps: A. Dissolving the temperature-responsive emulsifier in water to obtain an emulsifier solution; B. Preheating the epoxy resin to 35-45°C and mixing it with the emulsifier solution under stirring to obtain a mixture; C. Shearing and stirring the mixture; D. Steam-activated emulsification of the mixture; E. Ultrasonic dispersion of the mixture obtained in step D.

[0011] This invention also provides an epoxy resin emulsification device, which adopts the following technical solution: an epoxy resin emulsification device, comprising a shearing mechanism, a steam injection mechanism, an ultrasonic mechanism, and a support; the support has a vertical rod, on which a motor is slidably mounted; a spiral stirring head is disposed on the rotating shaft of the motor; a support rod extending downward along the bottom surface of the motor and parallel to the rotating shaft is disposed circumferentially on the motor, and the upper end of the support rod is connected to the outer casing of the motor; the steam injection mechanism includes a steam collector, which is connected to the lower end of the support rod; the steam collector is hollow and cylindrical, and has multiple steam injection holes disposed circumferentially on the steam collector; the rotating shaft passes through the steam collector, and the spiral stirring head is disposed above the steam collector; the shearing mechanism includes a mechanical shearing head, which is disposed on the rotating shaft corresponding to the position below the steam collector; the ultrasonic mechanism includes a transducer, which is disposed on the support rod.

[0012] Beneficial effects: The temperature-responsive emulsifier of the present invention helps to regulate the surface activity of the emulsifier, overcoming the technical limitations of traditional static emulsifiers.

[0013] The epoxy resin emulsion of the present invention has a particle size that can be controlled within the range of 50-500 nm, which is significantly smaller than that of epoxy resin emulsions prepared by traditional processes (the particle size of epoxy resin emulsions prepared by traditional processes is about 300-1000 nm; the smaller the particle size, the better it is for the uniform dispersion and stability of epoxy resin in water), and the storage stability is also better, the applicable temperature range is wider, and the overall performance of the product is significantly improved. Attached Figure Description

[0014] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 This is a schematic diagram of the overall structure of an epoxy resin emulsification device provided in one embodiment of the present invention; Figure 2 for Figure 1 A magnified view of a portion of the image; Figure 3 This is a schematic diagram of the structure of a steam generator provided in one embodiment of the present invention; Figure 4 Here is a schematic diagram of a mechanical shear head; where (a) is a top view of the mechanical shear head and (b) is a partial enlarged view of the mechanical shear head. Figure 5 This is a schematic diagram of an ultrasonic oscillation device; Figure 6 Thermogravimetric analysis charts for Example 1, Comparative Example 6, and Comparative Example 9; Figure 7 The graph shows the dynamic light scattering test results of the epoxy resin emulsions of Examples 1-2 and the aqueous epoxy emulsions of Comparative Examples 1, 3, 5 and 11. Figure 8 The images show the effects of the epoxy resin emulsion of Example 1 and the aqueous epoxy emulsions of Comparative Examples 1 and 4 after freeze-thaw tests and after standing for 12 months. Figure label: 1-Bracket; 11-Vertical rod; 12-Base plate; 13-Switch controller; 14-Electric lifter; 21-Motor; 22-Shaft; 23-Spiral mixer head; 24-Support rod; 241-Transducer; 31-Mechanical shear head; 310-Protective housing; 311-First-stage shear head; 312-Second-stage shear head; 313-Third-stage shear head; 4-Ultrasonic oscillation mechanism; 51-Steam collector; 511-Steam nozzle; 521-Heating electromagnetic pump; 522-Water inlet pipe; 523-Steam outlet pipe; 524-Pressure controller; 53-Water-steam separator; 531-Steam outlet pipe; 532-Pressure gauge; 533-Pressure relief valve; 534-Valve. Detailed Implementation

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0016] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0017] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0018] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" and "second" may explicitly or implicitly include one or more features.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection or a movable connection, a detachable connection or a non-detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection or a connection that allows communication between the two components; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components, an indirect connection, or an interaction between two components.

[0021] This invention addresses the problem of achieving uniform dispersion of oily epoxy resins in water in existing technologies by providing a method for preparing a temperature-responsive emulsifier.

[0022] The method for preparing the temperature-responsive emulsifier according to the present invention includes the following steps: (1) mixing polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with water, dissolving it, and adjusting the pH to obtain a prepolymer solution; (2) adding N-isopropylacrylamide monomer and initiator to the prepolymer solution under nitrogen protection, heating the reaction to obtain a reaction solution; (3) adding a crosslinking agent to the reaction solution for crosslinking modification to obtain a crude product; (4) purifying and drying the crude product obtained in step (3) to obtain the temperature-responsive emulsifier.

[0023] This invention utilizes a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer as the main chain, and introduces thermosensitive poly(N-isopropylacrylamide) segments into the side chains via free radical graft copolymerization, resulting in an emulsifier with temperature-controlled emulsification properties. The polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer possesses a unique amphiphilic structure, where the polyoxyethylene segments provide hydrophilicity and the polyoxypropylene segments provide moderate hydrophobicity. This structure, synergistically with the temperature-responsiveness of PNIPAM, can form a "hydrophobic core" under high-temperature conditions. "Core-shell structure of hydrophilic shell (PEO)". If the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is replaced with other polymers, it may not be possible to achieve such precise molecular structure design and temperature response mechanism, especially in the steam-activated emulsification process where it is difficult to regulate surface activity.

[0024] Preferably, the molecular formula of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is: .

[0025] In a preferred embodiment of the method for preparing the temperature-responsive emulsifier of the present invention, the mass ratio of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer to the N-isopropylacrylamide monomer is 100:(15-25) (e.g., 100:15, 100:18, 100:20, 100:22, or 100:15), and the mass ratio of the initiator to the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is (0.5-1.2):100 (e.g., 0.5:100, 0.7:100, 0.9:10). The mass ratio of crosslinking agent to polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is (0.1-0.3):100 (e.g., 0.1:100, 0.2:100 or 0.3:100), and the mass ratio of water to polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is (150-200):100 (e.g., 150:100, 160:100, 170:100, 180:100, 190:100, 200:100). If the ratio of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer to N-isopropylacrylamide monomer is too high, the grafting amount of PNIPAM segments in the temperature-responsive emulsifier will be insufficient. This will weaken the temperature-responsive characteristics of the emulsifier, preventing it from undergoing sufficient phase transformation during steam-activated emulsification, thus affecting the optimization effect of interfacial activity. If the ratio of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer to N-isopropylacrylamide monomer is too low, excessive grafting of PNIPAM segments will result in the emulsifier molecules being too hydrophobic, reducing their water solubility and dispersibility at room temperature, and affecting their solubility in the emulsifier solution preparation stage.

[0026] Preferably, the molecular weight of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is 3000-6000 Da; the initiator is potassium persulfate, and the crosslinking agent is N,N'-methylenebisacrylamide.

[0027] In a preferred embodiment of the method for preparing the temperature-responsive emulsifier of the present invention, in step (1), the dissolution is carried out at 75-85°C (e.g., 75°C, 78°C, 80°C, 83°C, or 85°C), and the pH is adjusted to 6.5-7.5 (e.g., 6.5, 6.8, 7.0, 7.2, or 7.5); in step (2), the reaction temperature is controlled at 68-72°C (avoiding exceeding the lower critical solution temperature of NIPAM; e.g., 68°C, 69°C, 70°C, 71°C, or 72°C), the reaction time is 4-6 h (e.g., 4 h, 5 h, or 6 h), and the conversion rate is ≥95% (i.e., the conversion rate of N-isopropylacrylamide monomer; referring to N-isopropylacrylamide). The proportion of amide monomers converted into PNIPAM segments grafted onto the main chain, with a high conversion rate ensuring that the emulsifier has sufficient temperature-responsive segments); in step (3), after adding the crosslinking agent, the reaction is carried out at 55-65℃ (e.g., 55℃, 58℃, 60℃, 63℃ or 65℃) for 2-3 hours (e.g., 2 hours, 2.2 hours, 2.5 hours, 2.8 hours or 3 hours); in step (4), the purification method is dialysis, using a dialysis membrane with a molecular weight cutoff of 3500 Da (preferably, the dialysis time is 48 hours to remove unreacted monomers and small molecule impurities); the drying method is freeze drying (after freeze drying, a white loose powder emulsifier product is obtained).

[0028] Preferably, dialysis is performed in deionized water, and the dialysate is replaced every 6 hours during the dialysis process; the freeze-drying temperature is -40°C, the vacuum degree is 0.01 mbar, and the drying time is 24 hours.

[0029] The present invention also proposes a temperature-responsive emulsifier, which is prepared by the method described above in the embodiments of the present invention.

[0030] In a preferred embodiment of the temperature-responsive emulsifier of the present invention, the molecular formula of the temperature-responsive emulsifier is: Where a = 20-45, b = 15-35, and the grafting degree is 8wt%-15wt%. Here, a and b are mainly related to the molecular structure of the selected polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer; a represents the number of repeating units in the polyoxyethylene (PEO) chain, and b represents the number of repeating units in the polyoxypropylene (PPO) chain; the molecular formula of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is... During the preparation process, the grafting reaction of N-isopropylacrylamide mainly occurs on the PPO segment, forming... The structure is adjusted, but the basic numerical ranges of a and b are not changed. The values ​​of a and b have a significant impact on the performance of the emulsifier. The a value (PEO segment length) affects hydrophilicity and water solubility, while the b value (PPO segment length) affects hydrophobicity and temperature response. A suitable a / b ratio ensures that the emulsifier has appropriate interfacial activity at room temperature and can undergo effective conformational transformation when activated by high-temperature steam, thereby achieving optimized adjustment of HLB value and interfacial tension.

[0031] "Grafting degree of 8wt%-15wt%" refers to the grafting degree of N-isopropylacrylamide (PNIPAM); the grafting degree represents the percentage of PNIPAM segments grafted onto the main chain of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer relative to the total molecular weight of the emulsifier.

[0032] The present invention also provides an epoxy resin emulsification method, wherein the epoxy resin emulsification method of the present invention includes the step of mixing epoxy resin with a temperature-responsive emulsifier.

[0033] In a preferred embodiment of the epoxy resin emulsification method of the present invention, the method includes the following steps: A. Dissolving a temperature-responsive emulsifier in water to obtain an emulsifier solution; B. Preheating the epoxy resin to 35-45°C (e.g., 35°C, 38°C, 40°C, 43°C, or 45°C), and mixing it with the emulsifier solution under stirring to obtain a mixture; C. Shearing and stirring the mixture; D. Steam-activated emulsification of the mixture; E. Ultrasonic dispersion of the mixture obtained in step D. Steps C, D, and E are not construed as limiting the order of steps; for example, steam-activated emulsification and / or ultrasound can be performed simultaneously with shearing.

[0034] In the process of preparing waterborne epoxy emulsion, the core function of shearing and stirring in step C is to break the water-insoluble epoxy resin oil phase into micron or nano-sized droplets by applying strong mechanical force, and to stably disperse them in the aqueous phase. At the same time, the violent fluid movement ensures that emulsifiers and other additives are uniformly distributed in the system and quickly coat the newly formed oil-water interface. By reducing interfacial tension and forming steric hindrance or electrostatic repulsion barriers, the re-aggregation of droplets is effectively prevented, thereby obtaining a waterborne epoxy emulsion with uniform particle size distribution and stable storage.

[0035] For temperature-responsive emulsifiers, below 25°C, the poly(N-isopropylacrylamide) segments are in a swollen, hydrophilic state (forming a hydrogen bond network with water molecules), the molecular conformation is relatively extended, the block copolymer backbone maintains a relatively ordered arrangement, and the overall molecule exhibits moderate interfacial activity, with some surface active sites exposed, suitable for room temperature storage and initial dispersion; during steam-activated emulsification (85-105°C), the PNIPAM segments undergo a phase transition and shrink to a hydrophobic state (changing from hydrophilic to hydrophobic), while the PPO segments (polyoxyethylene-polyoxypropylene)... The enhanced thermal motion of the polypropylene oxide intermediate segment and PNIPAM segment in the olefin-polyoxyethylene triblock copolymer leads to increased activity and conformational extension, forming a core-shell structure of hydrophobic core (PPO-PNIPAM) and hydrophilic shell (PEO) (this core-shell structure is key to achieving efficient emulsification). Temperature response optimizes interfacial activity; for example, as temperature increases, the PNIPAM segment changes from a hydrophilic to a hydrophobic state, causing a change in the hydrophilic-lipophilic balance (HLB value) of the entire emulsifier molecule, resulting in enhanced interfacial activity (reduced interfacial tension). This change does not refer to the overall properties of the mixture, but rather to the surface activity parameters of the emulsifier molecules at different temperatures; during steam-activated emulsification at 85-105℃, the surface activity of the temperature-responsive emulsifier is adjusted from HLB=12-14 to HLB=8-10, the interfacial tension decreases from 35 mN / m to 18-22 mN / m, and the critical micelle concentration is significantly reduced, achieving a high-temperature enhanced emulsification effect. Furthermore, steam-activated emulsification generates intense turbulent motion in the shear region. The essential function of this turbulence is to accelerate the renewal rate of the interfacial liquid. The aqueous phase on the epoxy resin droplet surface absorbs heat and activates the emulsifier molecules, causing its temperature to drop. Turbulence can then replace the cooled interfacial liquid with a new, high-temperature aqueous phase at a speed far exceeding that of natural convection. The latent heat carried by the steam bubbles, released during the condensation phase change on the epoxy resin droplet surface, is also a key factor in improving emulsification efficiency. Moreover, a thermal boundary layer with a significant temperature gradient exists at the interface between the epoxy resin droplet and the aqueous phase. Heat transfer within this layer primarily relies on conduction, and its thermal resistance is much greater than that of convective heat transfer outside the boundary layer. The thickness of the thermal boundary layer directly determines the heat transfer efficiency; a greater thickness results in higher thermal resistance, longer activation time for the emulsifier's temperature response, and lower emulsification efficiency. The turbulence generated by high-temperature steam has a strong scouring and disturbance effect on the thermal boundary layer, especially when the steam system works in conjunction with the shear mechanism; this high-speed flow can effectively reduce the thickness of the thermal boundary layer. More importantly, the growth, rising (stirring), and collapse of bubbles at the interface generate high-speed microjets that can penetrate and disrupt the stable structure of the thermal boundary layer. When the thermal boundary layer thickness is minimized, the path for heat transfer from the aqueous phase to the emulsifier molecules is shortened, the thermal resistance is significantly reduced, and the kinetic rate (efficiency) of the temperature response process is significantly improved.

[0036] In a preferred embodiment of the epoxy resin emulsification method of the present invention, in step A, the mass of the temperature-responsive emulsifier is 2%-8% of the mass of the epoxy resin (e.g., 2%, 4%, 6% or 8%); in step B, mixing is carried out at a speed of 800 rpm for a time of 10-15 min (e.g., 10 min, 11 min, 12 min, 13 min, 14 min or 15 min); in step C, shearing includes first-stage shearing, second-stage shearing and third-stage shearing, with the rotational speeds of the first-stage shearing, second-stage shearing and third-stage shearing gradually increasing; in step D, when steam activates emulsification, the temperature of the steam is 100-120°C (e.g., 100°C, 110°C or 120°C); in step E, the frequency of ultrasound is 28-40 kHz (e.g., 28 kHz, 30 kHz, 33 kHz, 35 kHz, 37 kHz or 40 kHz). If the proportion of temperature-responsive emulsifier is too small, the number of emulsifier molecules will be insufficient to form a complete protective layer on the surface of epoxy resin droplets, resulting in inadequate emulsification. This will lead to increased emulsion particle size, uneven particle size distribution, and decreased stability. If the proportion of temperature-responsive emulsifier is too large, although it can provide more interfacial protection, it will have the following adverse effects: First, it will increase production costs; second, excessive emulsifier may lead to excessively high emulsion viscosity, affecting flowability and application performance; third, excess emulsifier may form micelles in the aqueous phase, affecting the optical properties and application performance of the emulsion; fourth, it may affect the performance of the epoxy resin coating after curing, because excessive surfactant residue will affect the mechanical properties and water resistance of the coating.

[0037] Preferably, in step C, the rotational speed of the first-stage shearing is 1200-2000 rpm (e.g., 1200 rpm, 1400 rpm, 1600 rpm, 1800 rpm, or 2000 rpm), and the time for the first-stage shearing is 10-15 min; the rotational speed of the second-stage shearing is 2000-2500 rpm (e.g., 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, or 2500 rpm), and the time for the first-stage shearing is 15-25 min (e.g., 15 min, 20 min, or 25 min); the rotational speed of the second-stage shearing is 3500-4000 rpm (e.g., 3500 rpm, 3600 rpm, 3700 rpm, 3800 rpm, 3900 rpm, or 4000 rpm), and the time for the first-stage shearing is 20-35 min (e.g., 20 min, 25 min, 30 min, or 35 min).

[0038] This invention also proposes an epoxy resin emulsification device. The epoxy resin emulsification device of this embodiment includes a shearing mechanism, a steam jetting mechanism, an ultrasonic mechanism, and a support 1. The support 1 has a vertical rod 11, on which a motor 21 is slidably mounted. A spiral stirring head 23 is mounted on the rotating shaft 22 of the motor 21. A support rod 24 extending downwards along the bottom surface of the motor 21 and parallel to the rotating shaft 22 is circumferentially arranged on the motor 21. The upper end of the support rod 24 is connected to the outer casing of the motor 21, and the lower end of the support rod 24 is connected to the steam jetting mechanism. A steam collector 51 is connected; the steam collector 51 is a hollow column with multiple steam nozzles 511 arranged around its circumference; a rotating shaft 22 is arranged through the steam collector 51 (the rotating shaft 22 is connected to the steam collector 51 with a sealed bearing), a spiral stirring head 23 is arranged on the rotating shaft 22 at a position corresponding to the upper part of the steam collector 51, and a mechanical shearing head 31 is arranged on the rotating shaft 22 at a position corresponding to the lower part of the steam collector 51; the ultrasonic mechanism includes a transducer 241, which is arranged on the support rod 24.

[0039] Preferably, the support 1 further includes a base plate 12, which is used to support a reaction container (not shown in the figure) containing the mixture obtained in step B, so as to facilitate the treatment of the mixture in the reaction container and realize the emulsification of epoxy resin.

[0040] Preferably, a wall-mounted distribution sensor is provided on the inner wall of the reaction vessel; a switch controller 13 is also provided on the vertical rod 11, the switch controller 13 is connected to the electrical components in the epoxy resin emulsification equipment, the wall-mounted distribution sensor in the reaction vessel is connected to the switch controller 13 via a connecting line, and the switch controller 13 is configured to receive and display the monitoring parameters of the sensor; an electric lifter 14 is also provided on the vertical rod 11, and the motor 21 is slidably connected to the vertical rod 11 via the electric lifter 14.

[0041] Preferably, the system also includes a steam generator, which comprises a heating electromagnetic pump 521 and a water-vapor separator 53. One end of the heating electromagnetic pump 521 is connected to a water inlet pipe 522, and the other end is connected to a water outlet pipe 523. The end of the water outlet pipe 523 away from the heating electromagnetic pump 521 is connected to the water-vapor separator 53. The water-vapor separator 53 is provided with an exhaust pipe 531, which is connected to the cavity of the steam collector 51. The heating electromagnetic pump 521 is used to heat water to a specific temperature of steam so that the steam can enter the water-vapor separator 53. The separated steam in the water-vapor separator 53 enters the steam collector 51 through the exhaust pipe 531, and is then ejected through the steam nozzles 511 provided on the surface of the steam collector 51.

[0042] Preferably, the water vapor separator 53 is also equipped with a pressure gauge 532, a pressure relief valve 533 and a valve 534 (for discharging the water separated by the water vapor separator 53; preferably, the valve 534 is a high-temperature resistant valve).

[0043] In a preferred embodiment of the epoxy resin emulsification equipment of the present invention, the mechanical shear head 31 of the shearing mechanism adopts a three-stage concentric ring structure. The mechanical shear head 31 includes a first-stage shear head 311, a second-stage shear head 312, and a third-stage shear head 313 from the outside to the inside. A protective shell 310 is also provided on the outer side of the first-stage shear head 311. The first-stage shear head 311, the second-stage shear head 312, and the third-stage shear head 313 work synchronously during shearing and are driven by the motor 21 to perform shearing.

[0044] Preferably, the outer diameter of the protective shell is 150mm; the diameter of the first-stage shear head (shearing ring diameter) is 95mm; the diameter of the second-stage shear head (shearing ring diameter) is 0.8-1.2mm; and the diameter of the third-stage shear head (shearing ring diameter) is 0.3-0.6mm. The ultrasonic mechanism is dual-frequency adjustable and has multiple transducers arranged in two layers, symmetrically distributed in a hexagonal pattern (i.e., transducers at the same height are distributed at the vertices of a regular hexagon), with a power of 0-4000W and an ultrasonic power density of 0.8-4.5W / cm². 3 The steam nozzle 511 has a diameter of 0.3-0.8mm and is distributed in a ring near the shearing zone. The steam generator has a power of 6500W, a steam temperature regulation accuracy of ±1℃, a response time of <10s, and a pressure of 0.1-0.8MPa.

[0045] Preferably, the ultrasonic oscillation mechanism includes multiple transducers 241, which are mounted on a support rod 24 (a control box can be externally installed to adjust the power and frequency of the ultrasonic oscillation mechanism). It employs a ring-shaped ultrasonic dispersion device and a dual-frequency adjustable design of 28kHz and 40kHz. The 24 transducers are arranged in a hexagonal symmetrical distribution in two layers (e.g., ...). Figure 5 As shown, six transducers at the same height are distributed at the vertices of a regular hexagon; this transducer arrangement differs from the single-layer or simple arrangement of conventional ultrasonic equipment, forming a three-dimensional, intersecting sound field network. This enables a more uniform and stronger ultrasonic field within the processing container, avoiding dead zones and improving the overall processing effect. The symmetrical hexagonal distribution is an optimized geometric layout that allows for the interference and superposition of sound waves, enhancing the ultrasonic dispersion effect. The 28kHz low frequency is used for coarse dispersion, effectively breaking up larger particle agglomerates. The 40kHz high frequency is used for fine dispersion, achieving uniform dispersion of nanoscale particles. The total power is continuously adjustable from 0-4000W, and the sound power density is 0.8-4.5W / cm³. 3The system employs a dual-frequency collaborative working mode under program control, initially using 28kHz for coarse dispersion and later using 40kHz for fine dispersion. The power parameters are optimized for the specific needs of the epoxy resin emulsification process, ensuring sufficient dispersion while avoiding excessive ultrasound that could decompose the emulsifier or break the epoxy resin molecular chains. The continuously adjustable power allows the equipment to adapt to emulsion systems with varying viscosities and solid contents.

[0046] This invention integrates an ultrasonic oscillation mechanism with a shearing mechanism and a steam jet mechanism into a single device, forming a synergistic emulsification system. Addressing the specific needs of temperature-responsive emulsifiers and epoxy resin emulsification, this invention features systematic optimization in frequency selection, power configuration, transducer layout, and synergistic operating modes, resulting in a dedicated ultrasonic oscillation mechanism suitable for the technical solution of this invention. These improvements are integral to the overall technical solution of this invention. The design ensures sufficient dispersion while avoiding excessive ultrasound that could lead to emulsifier decomposition or epoxy resin molecular chain breakage. The continuously adjustable power allows the device to adapt to emulsion systems with different viscosities and solid contents.

[0047] Preferably, the steam collector 51 is equipped with 36 steam nozzles 511, each with a diameter of 0.3-0.8 mm. These nozzles are arranged in a ring around the shear zone, generating a uniform and dense flow of microbubbles. The steam generator has a power of 6500W and supports dual-mode switching between precision temperature control and inert gas protection. The steam temperature is precisely regulated by a PID control system with a control accuracy of ±1℃ and a response time of less than 10 seconds. The steam pressure is controlled by an electric regulating valve with a pressure range of 0.1-0.8 MPa, allowing for flexible adjustment of the steam flow rate according to process requirements. This system not only provides the precise temperature required to activate the emulsifier, but the rising flow of the generated microbubbles also acts as a natural stirrer, enhancing mass transfer.

[0048] Preferably, the multi-parameter real-time monitoring system adopts a wall-mounted distribution design, integrating high-precision temperature sensors, viscosity sensors, and conductivity sensors (each sensor is positioned at different locations on the inner wall of the reaction vessel). The temperature sensor uses a platinum resistance element, with a detection range of -30℃ to 180℃ and an accuracy of ±0.1℃, and is installed on the inner wall of the reaction vessel. The viscosity sensor uses a vibration principle, with a detection range of 1-50000 cP and an accuracy of ±1%, monitoring changes in emulsion viscosity in real time. The conductivity sensor has a detection range of 0-5000 μS / cm and an accuracy of ±2%, monitoring changes in the ionic strength of the system to reflect the emulsification reaction process.

[0049] Preferably, the equipment supports inert gas protection (e.g., when steam is not required, nitrogen or other inert gases can be introduced into the reaction vessel 40 via a steam generator and steam collector) and a condensation system (e.g., condensation collection is achieved by installing condenser pipes on the reaction vessel). Inert gas protection, through nitrogen or argon purging, effectively prevents the oxidation reaction of epoxy resin under high-temperature conditions, protects the integrity of the molecular structure, and improves the chemical stability of the product. The condensation system enables the recovery of steam condensate, achieving water resource recycling, while also recovering some heat energy, reducing production costs. The reaction vessel employs a double-layer insulation design, which effectively reduces heat loss and improves energy utilization efficiency.

[0050] The following detailed description of the temperature-responsive emulsifier, preparation method, application, and epoxy resin emulsification equipment of the present invention is provided through specific embodiments.

[0051] The main reagents used in the following examples are as follows: the epoxy resin is E51 epoxy resin with an epoxy value of 0.51, purchased from Nantong Xingchen Synthetic Materials Co., Ltd.; the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer has a molecular weight of 3500 Da and a polyoxyethylene content of 70% (in the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, the molar ratio of polyoxyethylene to polyoxypropylene is 3:1), purchased from Shandong Tonglian Chemical Co., Ltd.; the N-isopropylacrylamide monomer has a purity of over 99%, purchased from Aladdin Reagent Co., Ltd.; and potassium persulfate is of analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0052] The main testing methods used in the following examples are: 1. Emulsion Particle Size Distribution and Polydispersity Index: A dynamic light scattering nanoparticle size analyzer was used. An appropriate amount of emulsion sample was diluted and placed in the sample cell, and measurements were taken at 25°C. The average particle size and polydispersity index of the emulsion were calculated by analyzing the autocorrelation function of the scattered light intensity fluctuation.

[0053] 2. Emulsion Storage Stability: The emulsion sample was sealed and stored in a constant temperature incubator (25±1℃). Samples were taken periodically to observe the appearance and test particle size changes. Stability evaluation indicators included: presence of stratification and sedimentation, and whether the particle size increase was less than 5%.

[0054] 3. Mechanical stability: Place a quantitative amount of emulsion sample in a centrifuge tube and centrifuge at 4000 rpm for 30 minutes using a high-speed centrifuge. Immediately after centrifugation, observe whether the sample shows stratification, precipitation, or demulsification.

[0055] 4. Freeze-thaw stability: The emulsion sample was frozen at -20°C for 16 hours, then thawed at 25°C for 8 hours, which constituted one cycle. After repeating 5 cycles, the apparent state of the sample was observed and changes in particle size distribution and viscosity were detected.

[0056] 5. Viscosity: Place the thoroughly mixed aqueous epoxy emulsion sample in a 25°C constant temperature water bath and allow it to stand at a constant temperature. Then, using a suitable rotational viscometer, select the predetermined rotor and speed, and completely immerse the rotor in the sample up to the marked line. Start the viscometer, and after the reading stabilizes, record its apparent viscosity value.

[0057] 6. Grafting Degree: The grafting degree was determined by thermogravimetric analysis (TGA) at a heating rate of 10°C per minute under a nitrogen atmosphere from room temperature to 600°C. The grafting degree was calculated based on the different thermal decomposition behaviors of the PNIPAM segments and main chain. The grafting degree was calculated based on the TGA test data. Where W0: the initial total mass of the sample; W 水 W1: Mass of the sample before the start of side chain decomposition (approximately 150°C); W2: Residual mass before the end of side chain decomposition and the start of main chain decomposition (approximately 350°C); W1-W2: Thermal decomposition weight loss of the PNIPAM side chains.

[0058] Example 1 The method for preparing the temperature-responsive emulsifier in this embodiment includes the following steps: (1) Mix 100 parts of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with 180 parts of deionized water, heat to 80°C to completely dissolve to obtain a transparent solution, and adjust the pH to 7.0 to obtain a prepolymer solution; (2) Under nitrogen protection, 20 parts of N-isopropylacrylamide monomer and 0.8 parts of potassium persulfate initiator were added to the prepolymer solution, and the temperature was raised to 70℃ for 5 hours (the monomer conversion rate reached 96.3%; by real-time monitoring of the viscosity change and infrared spectral characteristic peaks of the reaction system, the monomer conversion rate was ensured to reach more than 95%), and the reaction solution was obtained. (3) Add 0.2 parts of N,N'-methylenebisacrylamide crosslinking agent to the reaction solution for crosslinking modification (the crosslinking reaction was carried out at 60°C for 3 hours, and the gel content was 20.5%) to obtain the crude product; (4) The crude product obtained in step (3) was purified by dialysis (unreacted monomers and small molecule impurities were removed by dialysis using a dialysis membrane with a molecular weight cutoff of 3500 Da, and dialysis was performed in flowing deionized water for 48 hours, with the dialysis solution being replaced every 6 hours) and freeze-dried (freezing temperature -40℃, vacuum degree 0.01 mbar, drying time 24 hours) to obtain 110.86 parts of the temperature-responsive emulsifier of this embodiment in white powder form (yield of 92.8%; calculated according to (110.86 / [mass of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer + mass of N-isopropylacrylamide monomer × monomer conversion rate + mass of crosslinking agent] × 100%).

[0059] The molecular formula of the temperature-responsive emulsifier in this embodiment is: ; Where a=28, b=18, and the grafting degree is 12%. Parameters a and b are determined based on the original molecular structure of the selected polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer. The grafting degree is determined by thermogravimetric analysis (TGA). Figure 6 As shown (grafting degree was 12 wt%), the temperature was increased at a rate of 10 °C per minute, and the temperature was increased from room temperature to 600 °C under a nitrogen atmosphere. The grafting degree was calculated based on the different thermal decomposition behaviors of the PNIPAM segments and main chain. Simultaneously, gel permeation chromatography (GPC) was used to determine the molecular weight distribution of the product, confirming the successful conduct of the grafting reaction.

[0060] The preparation method of the epoxy resin emulsion in this embodiment includes the following steps: A. Dissolve 5 parts by mass of temperature-responsive emulsifier in 95 parts by mass of deionized water to obtain an emulsifier solution (which is slightly turbid). B. Preheat 100 parts of E51 epoxy resin to 40°C to reduce the initial viscosity, and mix it with the emulsifier solution under stirring (mix at 800 rpm for 15 min) to obtain a mixture; C. Perform shearing and stirring on the mixture (three-stage shearing with gradually increasing speed: the first stage of shearing runs at 2000 rpm for 15 minutes, mainly to pre-crush the epoxy resin and stir and blend the epoxy resin and emulsifier; the second stage of shearing runs at 2500 rpm for 15 minutes; the third stage of shearing runs at 4000 rpm for 20 minutes). D. Steam activation emulsification of the mixture; specifically, the steam system is started at the beginning of the third stage of shearing, with a temperature of 105°C and a flow rate of 60 mL / min. When the local system temperature at the mechanical shear head reaches 85°C (a temperature sensor is installed on the outer wall of the protective shell 310 to detect local temperature changes at the mechanical shear head; preferably, a temperature sensor can also be installed at other locations on the inner wall of the container), a temperature response change of the emulsifier is observed, and the local system instantly turns into a uniform milky white, indicating the achievement of enhanced emulsification. Simultaneously with the start of the third stage of shearing, the ultrasonic oscillation system is started, running at 28 kHz frequency and 2000 W for 5 minutes, and then at 40 kHz frequency and 1500 W for 15 minutes. The entire synergistic emulsification process lasts for 45 minutes. Finally, the condensation reflux system is started, and the temperature is reduced to 30°C at a rate of 2°C / min, yielding the epoxy resin emulsion of this embodiment. The epoxy resin emulsion prepared in this embodiment has a solid content of 50%, consistent with the specifications of commercially available standard emulsions, facilitating performance comparison.

[0061] Performance test results show that the average particle size of the emulsion is 265 nm (measured using dynamic light scattering method), and the particle size distribution is highly uniform. Figure 7 As shown in the image, the particle size distribution is uniform, with a polydispersity index of 0.25 (narrow and uniform particle size distribution). 92% of the particles are distributed in the 200-350 nm range, with no obvious large particles present. The emulsion has a uniform milky white appearance, without stratification or sedimentation (see image below for the effect after standing for 12 months). Figure 8 As shown, it is a uniform milky white color with no stratification or sedimentation. The viscosity test result is 1850 m. It exhibits excellent rheological properties. The emulsion remained stable after five freeze-thaw cycles (e.g., ...). Figure 8 (As shown).

[0062] Storage stability tests were conducted at 25°C, and the particles remained stable after 18 months with a particle size change of less than 5%. Mechanical stability was verified by high-speed centrifugation, with no stratification observed after centrifugation at 4000 rpm for 30 minutes.

[0063] Example 2 The method for preparing the temperature-responsive emulsifier in this embodiment includes the following steps: (1) Mix 100 parts of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with 185 parts of deionized water, heat to 80°C to completely dissolve to obtain a transparent solution, and adjust the pH to 7.0 to obtain a prepolymer solution; (2) Under nitrogen protection, 22 parts of N-isopropylacrylamide monomer and 0.1 parts of potassium persulfate initiator were added to the prepolymer solution, and the temperature was raised to 70℃ for 6 hours (the monomer conversion rate reached 97.2%; by real-time monitoring of the viscosity change and infrared spectral characteristic peaks of the reaction system, the monomer conversion rate was ensured to reach more than 95%), and the reaction solution was obtained. (3) Add 0.25 parts of N,N'-methylenebisacrylamide crosslinking agent to the reaction solution for crosslinking modification (the crosslinking reaction was carried out at 60°C for 3 hours, and the gel content was 22.8%) to obtain the crude product; (4) The crude product obtained in step (3) was purified by dialysis (unreacted monomers and small molecule impurities were removed by dialysis using a dialysis membrane with a molecular weight cutoff of 3500 Da, and dialysis was performed in flowing deionized water for 48 hours, with the dialysis solution being replaced every 6 hours) and freeze-dried (freezing temperature -40°C, vacuum degree 0.01 mbar, drying time 24 hours) to obtain the temperature-responsive emulsifier of this embodiment in white powder form (yield 93.8%).

[0064] The molecular formula of the temperature-responsive emulsifier in this embodiment is: ; Where a=28, b=18, and the grafting degree is 12.3wt%.

[0065] In this embodiment, the epoxy resin emulsion was prepared at an experimental temperature of 5°C and an initial epoxy resin temperature of 8°C, resulting in a viscosity increase of approximately 15 times compared to room temperature.

[0066] The preparation method of the epoxy resin emulsion in this embodiment includes the following steps: A. Dissolve 6 parts by mass of temperature-responsive emulsifier in 100 parts by mass of deionized water, extending the dissolution time to 30 minutes compared to the normal dissolution time, to ensure complete dissolution and obtain an emulsifier solution; B. Mix 100 parts by mass of E51 epoxy resin with the emulsifier solution under stirring (mixing at 1000 rpm for 25 minutes) to obtain a mixture. C. The mixture is sheared and stirred (three-stage shearing, with the speed of the mechanical shear head gradually increasing: the first stage shearing is run at 1200 rpm for 15 minutes, the second stage shearing is run at 2000 rpm for 20 minutes, and the third stage shearing is run at 3500 rpm for 25 minutes). D. The mixture was subjected to steam-activated emulsification. Specifically, the steam system was started at the beginning of the third stage of shearing, with a temperature of 120°C and a flow rate of 80 ml / min. When the local system temperature at the mechanical shear head reached 85°C, a temperature-responsive change in the emulsifier was observed, and the local system instantly turned into a uniform milky white, indicating the achievement of enhanced emulsification. Simultaneously with the start of the third stage of shearing, the ultrasonic oscillation system was started, running at 28 kHz frequency and 2000 W for 5 minutes, and then at 40 kHz frequency and 1500 W for 20 minutes. The entire synergistic emulsification process lasted for 60 minutes. Finally, the reflux condensation system was started, and the temperature was reduced to ambient temperature at a rate of 2°C / min, yielding the epoxy resin emulsion of this embodiment. The epoxy resin emulsion prepared in this embodiment has a solid content of 50%, consistent with the specifications of commercially available standard emulsions, facilitating performance comparison.

[0067] Performance test results showed that the emulsion had an average particle size of 285 nm, uniform particle size distribution, and a polydispersity index of 0.26. This is comparable to the product prepared at room temperature in Example 1 (e.g.,...). Figure 7 As shown, the particles (265 nm in diameter, polydispersity index 0.25) exhibited essentially the same performance, with a difference of only 7.5%. This demonstrates that the synergistic effect of precision steam local heating technology and temperature-responsive emulsifiers can effectively overcome the adverse effects of low-temperature environments on the emulsification process. The emulsion appeared uniformly milky white, without any stratification or sedimentation. The viscosity at ambient temperature (5°C) was 1950 mM. It exhibits excellent rheological properties. The emulsion remained stable after five freeze-thaw cycles.

[0068] Low-temperature storage stability testing is particularly important. The emulsion was stored at -25°C for 45 days, with weekly sampling and testing during this period. Test results showed that the emulsion performance remained stable, with a particle size increase rate of less than 5%, viscosity change within 8%, and no demulsification or freezing. The pass rate for 5 freeze-thaw cycles reached 93%, slightly lower than Example 1 but still considered excellent.

[0069] Example 3 The method for preparing the temperature-responsive emulsifier in this embodiment includes the following steps: (1) Mix 100 parts of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with 195 parts of deionized water, heat to 80°C to completely dissolve to obtain a transparent solution, and adjust the pH to 7.0 to obtain a prepolymer solution; (2) Under nitrogen protection, 25 parts of N-isopropylacrylamide monomer and 1.2 parts of potassium persulfate initiator were added to the prepolymer solution, and the temperature was raised to 70℃ and reacted for 6 hours (monomer conversion rate reached 97.5%) to obtain the reaction solution; (3) Add 0.3 parts of N,N'-methylenebisacrylamide crosslinking agent to the reaction solution for crosslinking modification (the crosslinking reaction was carried out at 60°C for 3 hours, and the gel content was 23.5%) to obtain the crude product; (4) The crude product obtained in step (3) was purified by dialysis (unreacted monomers and small molecule impurities were removed by dialysis using a dialysis membrane with a molecular weight cutoff of 3500 Da, and dialysis was performed in flowing deionized water for 48 hours, with the dialysis solution being replaced every 6 hours) and freeze-dried (freezing temperature -40°C, vacuum degree 0.01 mbar, drying time 24 hours) to obtain the temperature-responsive emulsifier of this embodiment in the form of a white powder (yield of 94.2%).

[0070] The molecular formula of the temperature-responsive emulsifier in this embodiment is: ; Where a=28, b=18, and the grafting degree is 13.7wt%.

[0071] The preparation method of the epoxy resin emulsion in this embodiment includes the following steps: A. Dissolve 2 parts by mass of temperature-responsive emulsifier in 54 parts by mass of deionized water to obtain an emulsifier solution (which is slightly turbid); B. Mix 100 parts by mass of E51 epoxy resin with the emulsifier solution under stirring (mix at 800 rpm for 20 min) to obtain a mixture; C. Shear and stir the mixture (start the three-stage shear system, gradually increasing the speed: the first stage shear runs at 1500 rpm for 10 minutes, the second stage shear runs at 2500 rpm for 25 minutes, and the third stage shear runs at 4000 rpm for 35 minutes). D. The mixture was subjected to steam-activated emulsification. Specifically, the steam system was started at the beginning of the third-stage shearing, with a temperature of 120°C and a flow rate of 80 ml / min. When the local system temperature at the mechanical shear head reached 85°C, a temperature-responsive change in the emulsifier was observed, and the local system instantly turned into a uniform milky white, indicating the achievement of enhanced emulsification. Simultaneously with the start of the third-stage shearing, the ultrasonic oscillation system was started, running at 28 kHz frequency and 2000 W for 5 minutes, and then at 40 kHz frequency and 1500 W for 30 minutes. The entire synergistic emulsification process lasted for 70 minutes. Finally, the condensation system was started, and the temperature was reduced to 30°C at a rate of 2°C / min, yielding the epoxy resin emulsion of this embodiment. The epoxy resin emulsion prepared in this embodiment has a solid content of 30%, which is significantly lower than that of commercially available conventional waterborne epoxy resins.

[0072] Performance test results show: The emulsion has an average particle size of 385 nm, uniform particle size distribution, and a polydispersity index of 0.29, indicating good dispersion uniformity. 89% of the particles are concentrated in the 300-500 nm range, with no obvious large particles present. The emulsion has a uniform milky white appearance and shows no stratification or sedimentation. The viscosity test result is 8500 m³ / s. After being stored at 25°C for 15 months, the emulsion remained stable, with no stratification, precipitation, or gel formation. The particle size change was 7%, and the viscosity change was within 12%. Mechanical stability testing, performed by centrifugation at 4000 rpm for 30 minutes, showed no stratification and a pass rate of 96%. High-speed shear stability testing, performed by treatment at 8000 rpm for 10 minutes, showed a particle size increase of 11%, indicating good shear resistance and the ability to withstand mechanical forces during coating. After five freeze-thaw cycles, the pass rate was 90%. High-solids content emulsions face greater challenges during freeze-thaw cycles due to their higher oil phase ratio, making ice crystal growth more likely to damage the emulsion structure. However, the epoxy emulsion in this example showed a 15% particle size increase and an 18% viscosity change after freeze-thaw cycles, and could be restored to normal use after stirring at room temperature.

[0073] Example 4 The method for preparing the temperature-responsive emulsifier in this embodiment includes the following steps: (1) Mix 100 parts of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with 180 parts of deionized water, heat to 80°C to completely dissolve to obtain a transparent solution, and adjust the pH to 7.0 to obtain a prepolymer solution; (2) Under nitrogen protection, 20 parts of N-isopropylacrylamide monomer and 0.9 parts of potassium persulfate initiator were added to the prepolymer solution, and the temperature was raised to 70℃ for 5 hours (the monomer conversion rate reached 96.5%; by real-time monitoring of the viscosity change and infrared spectral characteristic peaks of the reaction system, the monomer conversion rate was ensured to reach more than 95%), and the reaction solution was obtained. (3) Add 0.2 parts of N,N'-methylenebisacrylamide crosslinking agent to the reaction solution for crosslinking modification (the crosslinking reaction was carried out at 60°C for 3 hours, and the gel content was 21%) to obtain the crude product; (4) The crude product obtained in step (3) was purified by dialysis (unreacted monomers and small molecule impurities were removed by dialysis using a dialysis membrane with a molecular weight cutoff of 3500 Da, and dialysis was performed in flowing deionized water for 48 hours, with the dialysis solution being replaced every 6 hours) and freeze-dried (freezing temperature -40°C, vacuum degree 0.01 mbar, drying time 24 h) to obtain the temperature-responsive emulsifier of this embodiment in the form of a white powder (yield of 93.2%).

[0074] The molecular formula of the temperature-responsive emulsifier in this embodiment is: ; Where a=28, b=18, and the grafting degree is 12wt%.

[0075] The preparation method of the epoxy resin emulsion in this embodiment includes the following steps: A. Dissolve 8 parts by mass of temperature-responsive emulsifier in 225 parts by mass of deionized water to obtain an emulsifier solution (which is slightly turbid); B. Mix 100 parts by mass of E51 epoxy resin with the emulsifier solution under stirring (mix at 800 rpm for 15 min) to obtain a mixture. C. Shear and stir the mixture (start the three-stage shear system, gradually increasing the speed: the first stage shear runs at 1500 rpm for 10 minutes, the second stage shear runs at 2500 rpm for 15 minutes, and the third stage shear runs at 4000 rpm for 30 minutes). D. The mixture was subjected to steam-activated emulsification. Specifically, the steam system was started at the beginning of the third-stage shearing, with a temperature of 105°C and a flow rate of 60 ml / min. When the local system temperature reached 85°C at the mechanical shear head, a temperature-responsive change in the emulsifier was observed, and the local system instantly turned into a uniform milky white, indicating the achievement of enhanced emulsification. Simultaneously with the start of the third-stage shearing, the ultrasonic oscillation system was started, running at 28 kHz frequency and 2000 W for 5 minutes, and then at 40 kHz frequency and 1500 W for 25 minutes. The entire synergistic emulsification process lasted 55 minutes. Finally, the condensation system was started, and the temperature was reduced to 30°C at a rate of 2°C / min, yielding the epoxy resin emulsion of this embodiment. The epoxy resin emulsion prepared in this embodiment has a solid content of 30%, which is significantly lower than that of commercially available conventional waterborne epoxy resins.

[0076] Performance test results show that the emulsion has an average particle size of 255 nm, uniform particle size distribution, and a polydispersity index of 0.22. No large particles are present. The emulsion has a uniform milky white appearance and shows no stratification or sedimentation. The viscosity test result is 1000 m³ / s. After being stored at 25°C for 18 months, the emulsion remained stable without stratification or sedimentation, exhibiting a particle size change of less than 3% and a viscosity change of less than 6%. Regular sampling revealed that the emulsion maintained a uniform appearance with no significant supernatant separation or bottom sedimentation. Centrifugal stability testing at 4000 rpm for 30 minutes showed no stratification, with a pass rate of 98%. After five freeze-thaw stability tests, the emulsion remained stable, with a pass rate of 92%. Low-solids content emulsions are more susceptible to ice crystal growth during freeze-thaw cycles, but the waterborne epoxy emulsion in this embodiment showed a particle size increase of only 10% and a viscosity change of only 13% after freeze-thaw cycles, far superior to traditional products.

[0077] Example 5 The method for preparing the temperature-responsive emulsifier in this embodiment includes the following steps: (1) Mix 100 parts of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with 150 parts of deionized water, heat to 75°C to completely dissolve to obtain a transparent solution, and adjust the pH to 6.5 to obtain a prepolymer solution; (2) Under nitrogen protection, 15 parts of N-isopropylacrylamide monomer and 0.5 parts of potassium persulfate initiator were added to the prepolymer solution, and the temperature was raised to 70℃ and reacted for 4 hours (monomer conversion rate reached 95.2%) to obtain the reaction solution; (3) Add 0.1 parts of N,N'-methylenebisacrylamide crosslinking agent to the reaction solution for crosslinking modification (the crosslinking reaction was carried out at 55°C for 2 hours, and the gel content was 18.5%) to obtain the crude product; (4) The crude product obtained in step (3) was purified by dialysis (unreacted monomers and small molecule impurities were removed by dialysis using a dialysis membrane with a molecular weight cutoff of 3500 Da, and dialysis was performed in flowing deionized water for 48 hours, with the dialysis solution being replaced every 6 hours) and freeze-dried (freezing temperature -40°C, vacuum degree 0.01 mbar, drying time 24 hours) to obtain the temperature-responsive emulsifier of this embodiment in white powder form (yield 92%).

[0078] The molecular formula of the temperature-responsive emulsifier in this embodiment is: Where a=28, b=18, and the grafting degree is 8.8wt%.

[0079] The preparation method of the epoxy resin emulsion in this embodiment includes the following steps: A. Dissolve 2 parts by mass of temperature-responsive emulsifier in 98 parts by mass of deionized water to obtain an emulsifier solution (which is slightly turbid); B. Mix 100 parts by mass of E51 epoxy resin with the emulsifier solution under stirring (mix at 800 rpm for 10 min) to obtain a mixture. C. Shear and stir the mixture (start the three-stage shear system, gradually increasing the speed: the first stage shear runs at 1500 rpm for 10 minutes, the second stage shear runs at 2000 rpm for 15 minutes, and the third stage shear runs at 3000 rpm for 20 minutes). D. The mixture is subjected to steam-activated emulsification; specifically, the steam system is started at the onset of the third-stage shearing at a temperature of 105°C and a flow rate of 60 ml / min. Simultaneously with the onset of the third-stage shearing, the ultrasonic oscillation system is started, running at 28 kHz at 2000 W for 5 minutes and then at 40 kHz at 1500 W for 15 minutes. The entire synergistic emulsification process lasts for 45 minutes. Finally, the condensation system is started, and the temperature is reduced to room temperature at a rate of 2°C / min to obtain the epoxy resin emulsion of this embodiment.

[0080] Performance test results show that the emulsion has an average particle size of 298 nm, uniform particle size distribution, a polydispersity index of 0.27, and a uniform milky white appearance with no stratification or sedimentation. The viscosity test result is 1950 mM. Storage stability tests showed stability for 18 months with an 8% change in particle size. Low-temperature stability showed no demulsification for 30 days at -20°C. Mechanical stability showed a 95% throughput after centrifugation at 4000 rpm for 30 minutes.

[0081] Comparative Example 1 The waterborne epoxy emulsion prepared in this comparative example differs from that in Example 1 only in that the self-made temperature-responsive emulsifier is replaced with a commercially available conventional nonionic emulsifier (DY-56 nonionic emulsifier produced by Shenyang Dongyan Coatings & Decoration Co., Ltd.), while the rest of the preparation method is the same as in Example 1.

[0082] Performance test results show that the average particle size of the emulsion is 485 nm (e.g., Figure 7 As shown in the figure, the particle size distribution is relatively wide, with a polydispersity index of 0.42. Compared to Example 1 (particle size 265 nm, polydispersity index 0.25), the particle size increased by 83%, and the dispersion uniformity decreased significantly. The emulsion has a milky white appearance, but its uniformity is not as good as that of Example 1. The viscosity test result is 2850 m³ / s. It is 54% higher than that of Example 1, but has poorer fluidity.

[0083] Storage stability tests showed that slight stratification occurred after 6 months of storage at 25°C, and significant stratification occurred after 12 months (e.g., ...). Figure 8 As shown in the figure, the particle size increased by 23%. Mechanical stability testing showed slight stratification after centrifugation at 4000 rpm for 30 minutes, with a pass rate of only 85%, far lower than Example 1. After 5 freeze-thaw cycles, significant particle size increase and viscosity rise were observed, indicating significantly weaker freeze-thaw stability than Example 1.

[0084] This indicates that conventional nonionic emulsifiers, due to their lack of temperature responsiveness, cannot dynamically regulate interfacial activity during emulsification, resulting in poor emulsification effects and insufficient product stability.

[0085] Comparative Example 2 The aqueous epoxy emulsion prepared in this comparative example differs from the raw material composition of Example 1 only in that the mechanical shear head containing the first-stage shear head, the second-stage shear head and the third-stage shear head of the present invention is replaced with a conventional mechanical stirrer (single-stage paddle stirrer). The rest of the preparation method is the same as that of Example 1.

[0086] Performance test results show that the emulsion has an average particle size of 620 nm, a wide particle size distribution, and a polydispersity index of 0.51. Only 65% ​​of the particles are distributed in the 500-800 nm range, indicating the presence of significant large particles (particles with a diameter >1 μm account for 15%). The emulsion has a milky white appearance but is not uniform; slight particle size stratification can be observed after standing. The viscosity test result is 3250 mM. It is 76% higher than that of Example 1.

[0087] Storage stability tests showed that significant stratification occurred after 3 months of storage at 25°C, with a particle size increase of 35%. Mechanical stability tests showed severe stratification after centrifugation at 4000 rpm for 30 minutes, with a pass rate of only 62%. Significant demulsification was observed after 5 freeze-thaw cycles.

[0088] This indicates that ordinary mechanical stirring cannot provide sufficient shear force to achieve adequate dispersion of the oil phase. In particular, for high-viscosity epoxy resin systems, single-stage stirring is difficult to overcome viscous resistance, resulting in large and unevenly distributed emulsion particles, which seriously affects product stability.

[0089] Comparative Example 3 The aqueous epoxy emulsion prepared in this comparative example differs from the raw material components in Example 1 only in that: no high-temperature steam is involved in the preparation process, and the entire emulsification process is carried out at room temperature (25°C) (i.e., the steam-activated emulsification step in step D is omitted), while the rest of the preparation method is the same as in Example 1.

[0090] Performance test results show that the average particle size of the emulsion is 550 nm (e.g., Figure 7 As shown in the figure, the particle size distribution is relatively wide, with a polydispersity index of 0.46. Compared to Example 1 (particle size 265 nm, polydispersity index 0.25), the particle size increased by 108%. Only 70% of the particles are distributed in the 400-700 nm range, and large particles with a diameter >1 μm account for about 12%. The emulsion has a milky white appearance but poor uniformity. The viscosity test result is 2950 m³ / s. It is 59% higher than that of Example 1.

[0091] Observations during the emulsification process revealed that the temperature-responsive emulsifier was not fully activated at room temperature, and the system maintained a consistently high viscosity, resulting in significantly insufficient mixing and dispersion. Even with an extended shear time of 60 minutes, the particle size remained difficult to reduce to the ideal range.

[0092] Storage stability tests showed that stratification occurred after 9 months of storage at 25°C, with a particle size increase of 18%. The mechanical stability test pass rate was 76%. Bottom sedimentation occurred after 5 freeze-thaw cycles, with a particle size increase of 28%.

[0093] This indicates that temperature-responsive emulsifiers require high-temperature activation to achieve optimal emulsifying performance. At room temperature, the PNIPAM segments are in a swollen, hydrophilic state with weak interfacial activity (HLB value approximately 12-14), failing to effectively reduce interfacial tension. Without a steam activation step, the emulsifier cannot undergo a phase transition to form the optimal hydrophobic core-hydrophilic shell structure, resulting in a significant reduction in emulsifying effectiveness.

[0094] Comparative Example 4 The aqueous epoxy emulsion prepared in this comparative example differs from the raw material composition of Example 1 only in that the steam-activated emulsification step is replaced by ordinary external water bath heating (e.g., placing the entire reaction vessel in an 85°C water bath; or heating through the insulation system of the reaction vessel jacket). The rest of the preparation method is the same as that of Example 1.

[0095] Performance test results show: The emulsion has an average particle size of 420 nm, with uneven particle size distribution and a polydispersity index of 0.38. Compared to Example 1 (particle size 265 nm, polydispersity index 0.25), the particle size increases by 58%. Approximately 78% of the particles are distributed in the 300-600 nm range, but the particle size distribution exhibits a clear bimodal characteristic, indicating temperature inhomogeneity in the system. The emulsion has an overall milky white appearance, but variations in color intensity are observed. The viscosity test result is 2450 m³ / s. It is 32% higher than that of Example 1.

[0096] Temperature field monitoring revealed that when the temperature at the edge of the container reached 82°C, the temperature in the central area was only 58°C, resulting in a temperature gradient as high as 24°C.

[0097] Storage stability tests showed that stratification occurred after 12 months of storage at 25°C. The mechanical stability test pass rate was 82%. After 5 freeze-thaw cycles, the particle size increase exceeded 45%, and stratification and flocculation occurred (e.g., ...). Figure 8 (As shown in the image). This indicates that conventional water bath heating suffers from severe temperature unevenness, failing to ensure sufficient activation of the emulsifier while significantly increasing energy consumption. Precision steam local heating technology can create a uniform and stable temperature field in the shear zone, achieving precise activation of the emulsifier and avoiding overheating of the entire system, thus offering significant technical advantages and energy-saving effects.

[0098] Comparative Example 5 The aqueous epoxy emulsion prepared in this comparative example differs from that in Example 4 in that the shearing time of the three-stage shearing is shortened (the first stage runs at 1500 rpm for 5 minutes, the second stage runs at 2500 rpm for 8 minutes, and the third stage runs at 4000 rpm for 12 minutes, for a total of 25 minutes). The rest of the preparation method is the same as in Example 4.

[0099] Performance test results show that the average particle size of the emulsion is 580 nm (e.g., Figure 7 As shown in the figure, the particle size distribution is very wide, with a polydispersity index of 0.52. Compared to Example 4 (particle size 255 nm, polydispersity index 0.22), the particle size increased by 127%, and the dispersion uniformity decreased significantly. Only 62% of the particles were distributed in the 400-800 nm range, and large particles with a diameter >1.2 μm accounted for 18%, showing a bimodal particle size distribution. The emulsion appeared milky white overall, but obvious inhomogeneity was observed, and slight stratification appeared after standing for 5 minutes. The viscosity test result was 2850 m. It is 185% higher than that of Example 4, and its fluidity is significantly worse.

[0100] Storage stability tests showed that significant stratification occurred after one month of storage at 25°C, with the aqueous phase floating and the oil phase settling, and the interface clearly visible. After three months, stratification worsened, with particle size increasing by 38%. This is a typical stratification phenomenon in low-solids-content emulsions, caused by significant gravity sedimentation due to droplet density differences and an excess of aqueous phase. Mechanical stability tests revealed severe stratification after centrifugation at 4000 rpm for 30 minutes. The pass rate for five freeze-thaw cycles was only 45%, with a significantly increased particle size increase and substantial precipitation of the aqueous phase after freeze-thaw cycles.

[0101] This indicates that for low-solids emulsion systems, although lower viscosity facilitates handling, sufficient mechanical shear time is equally crucial for forming a stable dispersion. Insufficient shear time leads to incomplete initial droplet breakage, incomplete emulsifier adsorption, poor droplet interfacial stability, and ultimately, aggregation and stratification during storage. Example 4 employed a 55-minute gradient shearing (particularly a 30-minute high-speed fine shearing) to ensure sufficient droplet refinement and complete emulsifier adsorption, resulting in a long-term stable product even under low-solids conditions.

[0102] Comparative Example 6 The waterborne epoxy emulsion prepared in this comparative example differs from that in Example 1 in that the amount of N-isopropylacrylamide monomer is reduced to 10 parts (the mass ratio of N-isopropylacrylamide monomer to polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is 100:10), while the rest of the preparation method is the same as in Example 1.

[0103] Characterization results of temperature-responsive emulsifiers showed that the grafting degree was only 4.2 wt%, and the PNIPAM segment content was significantly insufficient.

[0104] Performance test results showed that the emulsion had an average particle size of 465 nm, a relatively wide particle size distribution, and a polydispersity index of 0.41. Compared to Example 1 (particle size 265 nm, polydispersity index 0.25), the particle size increased by 75%. Approximately 73% of the particles were distributed in the 350-650 nm range, but about 13% were large particles (particle size > 1 μm). The emulsion had a milky white appearance and moderate uniformity.

[0105] Storage stability tests showed that slight stratification occurred after 9 months of storage at 25°C, with a particle size increase of 16%. The mechanical stability test pass rate was 79%, and the particle size increase reached 21% after 5 cycles.

[0106] This indicates that insufficient N-isopropylacrylamide monomer dosage leads to inadequate PNIPAM segment grafting and weakened temperature response performance. Although the emulsifier still exhibits some temperature response characteristics, the phase transition is not significant enough, the interfacial activity adjustment range is narrow, and it cannot form an optimal hydrophobic core-hydrophilic shell structure at the activation temperature, resulting in poor emulsification and decreased product stability.

[0107] Comparative Example 7 The waterborne epoxy emulsion prepared in this comparative example differs from that in Example 1 in that the amount of N-isopropylacrylamide monomer is increased to 35 parts (the mass ratio of N-isopropylacrylamide monomer to polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is 100:35), while the rest of the preparation method is the same as in Example 1.

[0108] An abnormal phenomenon was observed during the preparation of the temperature-responsive emulsifier: the reaction system rapidly became turbid after being heated to 70°C, the viscosity increased sharply, and a clear tendency to gel was observed. This was due to excessive NIPAM monomer dosage, over-grafting reaction, and excessively long and dense PNIPAM segments, which exceeded the LCST at the reaction temperature, resulting in phase separation and aggregation. The final product was a heterogeneous semi-solid state, and the yield dropped to 76%, far lower than the 92.8% of Example 1.

[0109] Characterization results of the temperature-responsive emulsifier showed that the grafting degree was as high as 22.5 wt%, indicating an excessively high PNIPAM segment content. This emulsifier exhibited poor water solubility at room temperature and required a considerable amount of time to dissolve completely.

[0110] Performance test results showed that the emulsion had an average particle size of 520 nm, a wide particle size distribution, and a polydispersity index of 0.48. Compared to Example 1 (particle size 265 nm, polydispersity index 0.25), the particle size increased by 96%. The particle size distribution exhibited obvious multi-peak characteristics, indicating the presence of droplet clusters of different sizes in the system. Only 65% ​​of the particles were distributed in the 400-750 nm range, and large particles with a diameter >1.5 μm accounted for approximately 16%. The emulsion appeared milky white but was not uniform, and some aggregates could be observed. The viscosity test result was 3150 m³ / h. It is 70% higher than that of Example 1.

[0111] Storage stability tests showed that significant stratification and precipitation occurred after only 3 months of storage at 25°C, with a particle size increase of 32%. This was because the LCST of the emulsifier was too low, and the PNIPAM segments were in a hydrophobic state under normal temperature storage conditions. This caused the emulsifier molecules to aggregate, failing to effectively stabilize the emulsion droplets and leading to rapid instability. The mechanical stability test pass rate was 68%, and the particle size increase rate after 5 freeze-thaw cycles was 43%.

[0112] This indicates that excessive N-isopropylacrylamide monomer dosage can lead to multiple adverse effects, including increased efflorescence during preparation, reduced product yield, excessively long and dense PNIPAM segments resulting in a low LCST of the emulsifier and poor room temperature stability, and excessive hydrophobicity leading to decreased solubility and dispersibility of the emulsifier in water, making it difficult to form a stable emulsion system. A suitable monomer dosage range (15-25 parts) is crucial for obtaining optimal temperature response performance and emulsification effect.

[0113] Comparative Example 8 The epoxy emulsion prepared in this comparative example differs from that in Example 1 in that the reaction time after adding the initiator is shortened to 2 hours, while the rest of the preparation method is the same as in Example 1.

[0114] Monitoring of the temperature-responsive emulsifier preparation process showed that after 2 hours of reaction, the monomer conversion rate was only 78.5% according to infrared spectroscopy and viscosity measurements, far lower than the 96.3% in Example 1. A large amount of unreacted N-isopropylacrylamide monomer remained in the reaction solution. Although some unreacted monomer was removed during subsequent dialysis purification, a small amount of monomer remained in the final product (gas chromatography detected approximately 0.8% residual monomer content).

[0115] Characterization results of the temperature-responsive emulsifier showed that, due to insufficient monomer conversion, the grafting amount and chain length of the PNIPAM chain segments were both lower than the design values, with a grafting degree of only 6.8 wt%, lower than the target grafting degree (8-15 wt%) in Example 1. Molecular weight distribution testing showed that the product contained a large number of low molecular weight components, and the molecular weight distribution width was significantly increased.

[0116] Performance test results show: The emulsion has an average particle size of 435 nm, a relatively wide particle size distribution, and a polydispersity index of 0.39. Compared to Example 1 (particle size 265 nm, polydispersity index 0.25), the particle size is increased by 64%. Approximately 75% of the particles are distributed in the 330-620 nm range, but about 11% are large particles. The emulsion has a milky white appearance and moderate homogeneity. The viscosity test result is 2550 mM. It is 38% higher than that of Example 1.

[0117] Storage stability tests showed that slight stratification occurred after 6 months of storage at 25°C, with a particle size increase of 19%. The mechanical stability test pass rate was 81%, and the particle size increase rate was 18% after 5 freeze-thaw cycles. In addition, a trace odor was detected during long-term storage (after 12 months), which may be related to the slow volatilization of residual monomers.

[0118] This indicates that insufficient reaction time leads to inadequate monomer conversion, incomplete grafting of PNIPAM segments, and weakened temperature response performance. Furthermore, residual monomer may affect the long-term stability and safety of the product. Sufficient reaction time (4-6 hours) is essential to ensure high monomer conversion (≥95%), obtain ideal grafted structures, and achieve excellent product performance.

[0119] Comparative Example 9 The waterborne epoxy emulsion prepared in this comparative example differs from that in Example 1 in that the reaction time after adding the initiator is extended to 9 hours, while the rest of the preparation method is the same as in Example 1.

[0120] Monitoring of the temperature-responsive emulsifier preparation process showed that after 5 hours of reaction, the monomer conversion rate reached 96.8%, comparable to Example 1. Continuing the reaction for 9 hours only slightly increased the conversion rate to 97.2%, but the system viscosity increased significantly, and the color gradually changed from colorless and transparent to pale yellow. This indicates that after the monomers have basically reacted completely, extending the reaction time mainly leads to side reactions, including partial thermal degradation and oxidation of the PNIPAM segments, as well as possible inter-segment crosslinking.

[0121] Thermogravimetric analysis (TGA) showed that ( Figure 6 The thermal stability of this product is slightly lower than that of the product in Example 1, and the initial decomposition temperature is reduced by about 15°C.

[0122] Performance test results showed that the emulsion had an average particle size of 315 nm, a relatively wide particle size distribution, and a polydispersity index of 0.31. Compared to Example 1 (particle size 265 nm, polydispersity index 0.25), the particle size increased by 19%, but the increase was relatively small. Approximately 85% of the particles were distributed in the 240-450 nm range. The emulsion had a uniform milky white appearance, but the color was slightly darker than that of Example 1. The viscosity test result was 2150 m³ / s. It is 16% higher than that of Example 1.

[0123] Storage stability tests showed that after 15 months of storage at 25°C, the particle size increased by 11%, slightly higher than the 5% in Example 1. The mechanical stability test pass rate was 89%, and the particle size increase rate was 15% after 5 freeze-thaw cycles. Although the performance indicators were still within an acceptable range, they were significantly weaker than those in Example 1.

[0124] This indicates that while excessively long reaction times do not cause serious product quality problems, they can lead to side reactions, including thermal degradation, oxidation, and slight cross-linking of PNIPAM segments, reducing product purity and thermal stability, while also extending the production cycle and increasing energy consumption and costs. A suitable reaction time (4-6 hours) can ensure high conversion rates while minimizing side reactions, resulting in high-purity, high-performance temperature-responsive emulsifiers.

[0125] Comparative Example 10 The waterborne epoxy emulsion prepared in this comparative example differs from that in Example 1 in that the reaction time after adding the crosslinking agent is shortened to 1 hour, while the rest of the preparation method is the same as in Example 1.

[0126] Monitoring of the temperature-responsive emulsifier preparation process showed that after 1 hour of crosslinking reaction, the gel content was only 12.8%, far lower than the 20.5% in Example 1. This indicates that the crosslinking reaction was insufficient, and most polymer segments were still in a linear or slightly branched state, failing to form a sufficient three-dimensional network structure.

[0127] Characterization results of temperature-responsive emulsifiers showed that, due to insufficient crosslinking, the swelling degree of the product in water was significantly higher than that of Example 1, reaching 580% (approximately 320% in Example 1).

[0128] Performance test results showed that the emulsion had an average particle size of 395 nm, a relatively wide particle size distribution, and a polydispersity index of 0.36. Compared to Example 1 (particle size 265 nm, polydispersity index 0.25), the particle size increased by 49%. Approximately 80% of the particles were distributed in the 300-560 nm range, with about 10% being large particles. The emulsion had a milky white appearance and moderate uniformity. The viscosity test result was 2380 mM. It is 29% higher than that of Example 1.

[0129] Storage stability tests showed slight stratification after 9 months of storage at 25°C, with a particle size increase of 17%. This is because the emulsifier molecular chains with insufficient cross-linking were too soft, resulting in insufficient mechanical strength and poor resistance to deformation after interfacial adsorption, making the droplets prone to coalescence under external forces. The mechanical stability test pass rate was 77%, significantly lower than that of Example 1. After 5 freeze-thaw cycles, the particle size increase was 17%, indicating significant droplet coalescence during the freeze-thaw process.

[0130] This indicates that an insufficient crosslinking reaction time leads to inadequate crosslinking degree, resulting in emulsifier molecules lacking a suitable three-dimensional network structure. The protective layer formed at the interface has insufficient mechanical strength and elasticity, failing to effectively prevent droplet coalescence and causing a decrease in emulsion stability. A sufficient crosslinking reaction time (2-3 hours) is crucial for obtaining a suitable degree of crosslinking and optimizing emulsifier performance.

[0131] Comparative Example 11 The waterborne epoxy emulsion prepared in this comparative example differs from that in Example 1 in that the reaction time after adding the crosslinking agent is extended to 5 hours, while the rest of the preparation method is the same as in Example 1.

[0132] Monitoring of the temperature-responsive emulsifier preparation process showed that after 5 hours of crosslinking reaction, the gel content reached as high as 38.5%, far exceeding the 20.5% in Example 1. The viscosity of the reaction system increased significantly, and the product exhibited a hard gel state, making it difficult to fully dissolve and disperse.

[0133] Characterization results of the temperature-responsive emulsifier showed that, due to excessive crosslinking, the swelling degree of the product in water was significantly reduced to only 180% (compared to approximately 320% in Example 1). This indicates that excessive crosslinking restricts the mobility of polymer segments and reduces the interaction ability between hydrophilic segments and water molecules.

[0134] Performance test results show that the average particle size of the emulsion is 505 nm (test results are as follows). Figure 7 As shown in the figure, the particle size distribution is very wide, with a polydispersity index of 0.45. Compared to Example 1 (particle size 265 nm, polydispersity index 0.25), the particle size increased by 91%. Only 70% of the particles are distributed in the 380-720 nm range, and large particles with a diameter >1 μm account for about 14%. The emulsion has a milky white appearance but is not uniform, and some large particles can be observed. The viscosity test result is 2980 m. It is 61% higher than that of Example 1.

[0135] Emulsification performance analysis revealed that while the over-crosslinked emulsifier possessed high mechanical strength, its flexibility and interfacial activity were significantly reduced. The overly rigid molecular structure made it difficult for it to effectively adsorb and spread at curved droplet interfaces, resulting in incomplete interfacial coverage and decreased emulsification efficiency. Temperature response performance testing showed that the phase transition of this emulsifier was not significant enough, and the phase transition temperature range was widened. This is because excessive crosslinking restricted the conformational transformation of the PNIPAM segments.

[0136] Storage stability tests showed that after 12 months of storage at 25°C, the particle size increased by 15%, slightly higher than in Example 1. The mechanical stability test pass rate was 85%, and the particle size increase rate was 31% after 5 freeze-thaw cycles.

[0137] This indicates that excessively long cross-linking reaction times lead to over-cross-linking, resulting in an overly rigid emulsifier molecular structure, reduced flexibility and interfacial activity, weakened temperature response, and decreased adsorption and spreading capacity at the interface, ultimately leading to poor emulsification. Moderate cross-linking (2-3 hours reaction, gel content 18%-23%) can maintain sufficient flexibility and temperature responsiveness while ensuring molecular mechanical strength, achieving optimal emulsification performance.

[0138] Comparative Example 12 The epoxy emulsion prepared in this comparative example differs from that in Example 1 in that the amount of temperature-responsive emulsifier is reduced to 1% of the epoxy resin mass, while the rest of the preparation method is the same as in Example 1.

[0139] Performance test results show that the emulsion has an average particle size of 950 nm, an extremely wide particle size distribution, and a polydispersity index of 0.72. Only 45% of the particles are distributed in the 700-1500 nm range, while large particles with a diameter >2 μm account for as much as 35%, exhibiting a very wide multi-peak particle size distribution. The emulsion appears milky white but is very uneven, with obvious large particles suspended in it. After standing for 10 minutes, it quickly separates into layers: a thin aqueous phase on top and a high-viscosity concentrated emulsion phase at the bottom. The viscosity of the lower liquid is 5850 mV. .

[0140] Emulsification mechanism analysis revealed that a severe deficiency in emulsifier dosage was the root cause of emulsification failure. According to emulsification theory, the emulsifier needs to form a complete adsorption layer at the droplet interface to effectively reduce interfacial tension and provide steric stabilization. When the emulsifier dosage was only 1%, based on the amounts of epoxy resin and water, the emulsifier coverage at the interface was less than 50%. This large amount of exposed interface led to droplet aggregation, preventing the formation of a stable emulsion system. Although localized emulsification could be observed during steam-activated emulsification, the insufficient total amount of emulsifier caused the newly formed droplets to quickly lose their protection and re-aggregate into larger droplets.

[0141] Storage stability tests showed that the emulsion exhibited severe stratification after only one week of storage at 25°C, with a clear and transparent upper aqueous phase and a viscous resin phase at the lower phase, with a clear interface. After one month, it almost completely decomposed, with a particle size increase of over 80%. Mechanical stability tests showed complete demulsification after centrifugation at 4000 rpm for 30 minutes, with a pass rate of 0%, and complete demulsification after one freeze-thaw cycle.

[0142] This indicates that insufficient emulsifier dosage leads to incomplete interfacial coverage and prevents the formation of a stable emulsion system. Although temperature-responsive emulsifiers have excellent temperature control properties, their dosage must meet basic interfacial adsorption requirements to be effective.

[0143] Comparative Example 13 The epoxy emulsion prepared in this comparative example differs from that in Example 1 in that the amount of temperature-responsive emulsifier is increased to 12% of the epoxy resin mass, while the rest of the preparation method is the same as in Example 1.

[0144] Performance test results show that the emulsion has an average particle size of 585 nm and a polydispersity index of 0.68. Only about 50% of the particles are distributed in the 400-800 nm range, with obvious large particles (particles with a diameter > 1.5 μm account for about 22%). The particle size distribution exhibits a multi-peak characteristic, indicating significant droplet aggregation and uneven dispersion in the system. The emulsion appears milky white but has poor homogeneity; particle sedimentation and phase separation can be observed within a short time after standing. The viscosity test result is 3420 m³ / h. It is about 85% higher than that of Example 1, and its fluidity is significantly worse.

[0145] The emulsion showed obvious stratification after only 3 months of storage at 25°C, with a particle size increase of 45%. Mechanical stability testing showed severe stratification after centrifugation at 4000 rpm for 30 minutes, with a pass rate of only 58%. After 5 freeze-thaw cycles, the emulsion was basically demulsified, and the particle size increase rate exceeded 65%, indicating a significant deterioration in the stability of the system.

[0146] The above results indicate that exceeding the reasonable range of emulsifier dosage (2-8%) not only fails to improve emulsification but also leads to increased emulsion particle size, wider distribution, and decreased stability due to factors such as interfacial adsorption imbalance, micelle competition, and deterioration of system rheological properties. Therefore, a suitable emulsifier dosage (2-8%, preferably 5%) can achieve the best balance between emulsification effect, product performance, and economy.

[0147] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a temperature-responsive emulsifier, characterized in that, Includes the following steps: (1) Mix the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with water, dissolve it, and adjust the pH to obtain a prepolymer solution; (2) Under nitrogen protection, N-isopropylacrylamide monomer and initiator are added to the prepolymer solution, and the temperature is raised to react and a reaction solution is obtained; (3) Add a crosslinking agent to the reaction solution to perform crosslinking modification and obtain a crude product; (4) The crude product obtained by step (3) is purified to obtain the temperature-responsive emulsifier.

2. The method for preparing the temperature-responsive emulsifier as described in claim 1, characterized in that, The mass ratio of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer to the N-isopropylacrylamide monomer is 100:(15-25); The mass ratio of the initiator to the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is (0.5-1.2):100; The mass ratio of the crosslinking agent to the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer is (0.1-0.3):100; Preferably, the initiator is potassium persulfate; the crosslinking agent is N,N'-methylenebisacrylamide.

3. The method for preparing the temperature-responsive emulsifier as described in claim 1, characterized in that, In step (1), the dissolution is carried out at 75-85°C, and the pH is adjusted to 6.5-7.5; In step (2), the reaction temperature is controlled at 68-72℃, the reaction time is 4-6h, and the conversion rate is ≥95%; In step (3), after adding the crosslinking agent, the reaction is carried out at 55-65℃ for 2-3 hours; In step (4), the purification method is dialysis, which is performed using a dialysis membrane with a molecular weight cutoff of 3500 Da.

4. A temperature-responsive emulsifier, characterized in that, It is prepared by the method described in any one of claims 1-3.

5. The temperature-responsive emulsifier as described in claim 4, characterized in that, The molecular formula of the temperature-responsive emulsifier is: ; Where a=20-45, b=15-35, and the grafting degree is 8wt%-15wt%.

6. An epoxy resin emulsion, characterized in that, The epoxy resin emulsion comprises epoxy resin, a temperature-responsive emulsifier as described in claim 4 or 5, and water.

7. The method for preparing the epoxy resin emulsion as described in claim 6, characterized in that, Includes the following steps: A. Dissolve the temperature-responsive emulsifier in water to obtain an emulsifier solution; B. Preheat the epoxy resin to 35-45°C, and mix it with the emulsifier solution under stirring to obtain a mixture; C. Shear and stir the mixture; D. The mixture is subjected to steam-activated emulsification; E. The mixture obtained in step D is ultrasonically dispersed.

8. The method for preparing the epoxy resin emulsion as described in claim 7, characterized in that, In step A, the mass of the temperature-responsive emulsifier is 2%-8% of the mass of the epoxy resin; In step B, the mixing is carried out at a speed of 800 rpm for a time of 10-15 minutes. In step C, the shearing includes first-stage shearing, second-stage shearing, and third-stage shearing, with the rotational speeds of the first-stage shearing, second-stage shearing, and third-stage shearing gradually increasing. In step D, the temperature of the steam is 100-120℃ during steam-activated emulsification; In step E, the frequency of the ultrasound is 28-40 kHz.

9. An epoxy resin emulsification device, characterized in that, The epoxy resin emulsification equipment includes a shearing mechanism, a steam jetting mechanism, an ultrasonic mechanism, and a support frame; The support has a vertical rod, on which a motor is slidably mounted. A spiral stirring head is provided on the rotating shaft of the motor. A support rod extending downward along the bottom surface of the motor and parallel to the rotating shaft is provided around the motor. The upper end of the support rod is connected to the outer casing of the motor. The steam injection mechanism includes a steam collector connected to the lower end of the support rod. The steam collector is a hollow column with multiple steam injection holes arranged around its circumference. The rotating shaft passes through the steam collector, and the spiral stirring head is positioned above the steam collector. The shearing mechanism includes a mechanical shearing head, which is disposed on the rotating shaft at a position corresponding to the lower part of the steam collector; The ultrasonic mechanism includes a transducer, which is mounted on the support rod.

10. The epoxy resin emulsification equipment as described in claim 9, characterized in that, The mechanical shearing head of the shearing mechanism has a first-stage shearing head, a second-stage shearing head, and a third-stage shearing head arranged sequentially from the outside to the inside; a protective shell is also provided on the outside of the first-stage shearing head. Multiple transducers are provided, and the multiple transducers are arranged in a hexagonal symmetrical distribution in two layers; The steam injection mechanism also includes a steam generator, which is connected to the steam collector and is used to supply steam to the steam collector.

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