Equipment for preparing waterborne polyurethane resin through continuous emulsification and production process

Abstract

The invention belongs to the field of high polymer materials, and particularly relates to equipment for preparing waterborne polyurethane resin through continuous emulsification and a production process. The equipment for preparing the waterborne polyurethane resin through continuous emulsification comprises a prepolymer synthesis device, a water adding device, a continuous emulsification device, a post-chain extension device and a supercritical CO2 adding device, is a complete device which is compact in structure, reasonable in design and easy to manufacture, and adopts a supercritical CO2 continuous viscosity reduction and continuous shearing emulsification process at the same time; the steps of prepolymer synthesis, supercritical COviscosity reduction, water adding dispersion, continuous emulsification, post chain extension and the like are organically integrated, online viscosity reduction, accurate proportion feeding and efficient continuous emulsification of the polyurethane prepolymer are achieved, the pressure-resistant requirement of the continuous emulsification process for reaction equipment is effectively lowered, the production efficiency and product consistency are greatly improved, and the production cost is reduced. The method is suitable for large-scale and environment-friendly production of various waterborne polyurethanes.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and in particular relates to equipment and a production process for preparing waterborne polyurethane resin by continuous emulsification. Background Art

[0002] Waterborne polyurethane (WPU) is a type of environmentally friendly polyurethane resin that uses water as a dispersion medium, replacing organic solvents. Since its invention by Dr. Otta Bayer in 1937, continuous advancements in synthesis technology have driven the continuous optimization of WPU's performance and the rapid expansion of its application range. Currently, WPU is widely used in coatings, adhesives, leather, textiles, paper, plastics, rubber, and other fields. Entering the 21st century, the global emphasis on environmental regulations and sustainable development has further accelerated the development of the WPU industry.

[0003] At present, emulsification of polyurethane resin with low viscosity is a necessary condition for obtaining waterborne polyurethane emulsion with good performance. Therefore, acetone is usually used as a viscosity reducer in industrial production. For example, US4857565 discloses a continuous emulsification process using acetone as a solvent. The prepolymer, water and chain extender are briefly emulsified in a high-power mixer, and then the solvent is quickly removed through a circulating evaporator, thereby achieving continuous production. The article "A Brief Introduction to Hot Issues in Waterborne Polyurethane Patent Technology" (Polyurethane Industry, 2019, 34(1): 1-4.) also conducts a detailed investigation of the patent application status of continuous mechanical dispersion process for producing polyurethane emulsion at home and abroad, indicating that the industry is continuously exploring the use of continuous emulsification process to prepare waterborne polyurethane resin in order to achieve efficient production of waterborne polyurethane. In fact, although the continuous mechanical dispersion process has been patented internationally and is continuously explored and promoted in the industry, the current domestic production of waterborne polyurethane is still mainly based on the intermittent method, which has mature technology, low equipment investment and flexible operation. However, the batch emulsification process has significant disadvantages such as low production efficiency, high energy consumption, high labor intensity, large quality fluctuations between batches, and difficulty in scalability. At the same time, although the acetone method can effectively reduce the viscosity of the prepolymer and facilitate dispersion, its removal requires additional vacuum distillation equipment, which increases energy consumption and equipment costs. In addition, it is difficult to completely remove residual solvents. As a result, residual acetone in the emulsion not only increases environmental and VOC emission pressures, but may also affect the long-term stability and safety of the product. Therefore, with the increasing demand for efficient, green, and low-VOC production, the batch emulsification method combined with the acetone process, although traditional and mature, has gradually revealed obvious limitations.

[0004] In summary, in order to solve the problems of low efficiency, high energy consumption and difficulty in completely removing acetone residues in the existing intermittent emulsification process, it is urgent to develop a water-based polyurethane resin preparation equipment and supporting process that can achieve continuous and efficient emulsification, which will not only improve production efficiency and product consistency, but also meet the industrial development needs of green environmental protection and low VOC emissions. Summary of the Invention

[0005] In response to the above-mentioned problems existing in the prior art, the present invention aims to provide an apparatus for preparing waterborne polyurethane resin by continuous emulsification. Another object of the present invention is to provide a production process for preparing waterborne polyurethane resin by continuous emulsification. The present invention uses a complete set of equipment with a compact structure, reasonable design, and ease of manufacture, while simultaneously adopting supercritical CO2 continuous viscosity reduction and continuous shear emulsification processes to organically integrate the steps of prepolymer synthesis, supercritical CO2 viscosity reduction, water dispersion, continuous emulsification, and post-chain extension. This achieves online viscosity reduction, precise proportion feeding, and efficient continuous emulsification of polyurethane prepolymers, effectively reduces the pressure resistance requirements of the continuous emulsification process on the reaction equipment, significantly improves production efficiency and product consistency, and is suitable for large-scale, green and environmentally friendly production of various waterborne polyurethanes.

[0006] In order to solve the above problems, the technical solutions adopted by the present invention are as follows: A device for preparing waterborne polyurethane resin by continuous emulsification, comprising a prepolymer synthesis device, a water adding device, an emulsifying device, a post-chain extension device, and a supercritical CO2 adding device; The supercritical CO2 addition device includes a first booster pump, a second booster pump, a first pressure gauge, a second pressure gauge, a first flow meter, a second flow meter, a first check valve, a second check valve, a gas storage tank, a gas valve, a heat exchanger, a first thermometer, a first proportional feeder, and a static mixer; wherein the first booster pump, the first pressure gauge, the first flow meter, the first check valve, and the first proportional feeder are connected in series with the static mixer, the gas storage tank, the gas valve, the heat exchanger, the first thermometer, the second booster pump, the second pressure gauge, the second flow meter are connected in series with the second check valve, and the second check valve is connected to the first proportional feeder; The water adding device includes a third flow meter, a third one-way valve, a water tank, a water tank valve, a third booster pump, a third pressure gauge, a fourth flow meter, a fourth one-way valve, a second proportional feeder, and a second thermometer; wherein the water tank, the water tank valve, the third booster pump, the third pressure gauge, the fourth flow meter, the fourth one-way valve, the second proportional feeder and the second thermometer are connected in series, the third flow meter and the third one-way valve are connected in series, and the third one-way valve is connected to the second proportional feeder; The prepolymer synthesis device is connected with a first booster pump of the supercritical CO2 adding device, a static mixer of the supercritical CO2 adding device is connected with a third flow meter of the water adding device, the water adding device is connected with the emulsifying device, and the emulsifying device is connected with the post chain extension device.

[0007] The application designs a set of production devices, which organically integrates the steps of prepolymer synthesis, supercritical CO2 viscosity reduction, water dispersion, continuous emulsification and post chain extension, reduces the viscosity of polyurethane resin by supercritical carbon dioxide (scCO2), then continuously emulsifies the obtained low-viscosity polyurethane resin, finally obtains water-based polyurethane resin without organic solvent assisted emulsification, realizes online viscosity reduction, precise proportion feeding and high-efficiency continuous emulsification of polyurethane prepolymer, and effectively reduces the pressure resistance requirement of the reaction equipment for the continuous emulsification process.

[0008] Further, the prepolymer synthesis device is a normal-pressure reaction kettle, the emulsifying device is a horizontal high-speed continuous emulsifier, and the post chain extension device is a normal-pressure reaction kettle.

[0009] Further, the prepolymer synthesis device comprises a synthesis reaction kettle tank body, a synthesis reaction kettle stirring paddle, a synthesis reaction kettle heating device, a feeding port, a synthesis reaction kettle pressure gauge, a synthesis reaction kettle thermometer, a discharge port and a synthesis reaction kettle valve, the synthesis reaction kettle tank body is in a hollow structure and is internally provided with the synthesis reaction kettle stirring paddle, the feeding port, the synthesis reaction kettle pressure gauge and the synthesis reaction kettle thermometer are arranged on the top of the synthesis reaction kettle tank body, the synthesis reaction kettle heating devices are arranged on the two sides of the synthesis reaction kettle tank body, and the discharge port is located at the bottom of the synthesis reaction kettle tank body and is connected with the synthesis reaction kettle valve.

[0010] The post chain extension device comprises a chain extension reaction kettle tank body, a chain extension reaction kettle stirring paddle, a chain extension reaction kettle heating device, a feeding port, a chain extension reaction kettle pressure gauge and a chain extension reaction kettle thermometer, the chain extension reaction kettle tank body is in a hollow structure and is internally provided with the chain extension reaction kettle stirring paddle, the chain extension reaction kettle heating devices are arranged on the two sides of the chain extension reaction kettle tank body, and the feeding port, the chain extension reaction kettle pressure gauge and the chain extension reaction kettle thermometer are arranged on the top of the chain extension reaction kettle tank body.

[0011] The application also provides a production process for continuously emulsifying and preparing water-based polyurethane resin, which is produced by using the equipment for continuously emulsifying and preparing water-based polyurethane resin as described above and comprises the following steps. S1: completing the synthesis of polyurethane prepolymer in the prepolymer synthesis device; S2: starting the supercritical CO2 generating device, pressurizing the polyurethane prepolymer obtained in S1 by a first booster pump and then conveying it to a first proportional feeder; CO2 is heated by a gas storage tank through a heat exchanger and pressurized by a second booster pump, and then conveyed to the first proportional feeder while maintaining a supercritical state; then, the first proportional feeder simultaneously conveys the polyurethane prepolymer and supercritical CO2 to a static mixer, thereby obtaining a polyurethane prepolymer having a viscosity reduced by supercritical CO2; S3: The water adding device is turned on to convey the polyurethane prepolymer subjected to supercritical CO2 viscosity reduction from the static mixer to the second proportional feeder of the water adding device; the water or the aqueous solution of the salt-forming agent in the water tank is pressurized by the third booster pump and conveyed to the second proportional feeder, and then conveyed together with the polyurethane prepolymer subjected to supercritical CO2 viscosity reduction through the second proportional feeder to the emulsification device, and then emulsification is completed in the emulsification device to obtain a continuously emulsified waterborne polyurethane resin; S4: starting the post-chain extension device, and then conveying the continuously emulsified waterborne polyurethane resin obtained in S3 to the post-chain extension device for stirring to obtain an organic solvent-free emulsified waterborne polyurethane resin; The production process is suitable for the preparation of nonionic, cationic and anionic waterborne polyurethanes.

[0012] The use of carbon dioxide (CO2) is very common in modern life. In addition to the three common states of gas, liquid and solid, carbon dioxide also has another state that is not well known to people - supercritical carbon dioxide (scCO2). This scCO2 is carbon dioxide with a temperature and pressure above the critical temperature and critical pressure. It has the advantages of being safe and non-toxic, low-priced, abundant in reserves, large in production scale and high in product purity. The present invention innovatively uses supercritical CO2 as a solvent to replace organic solvents with a boiling point below 100°C, and uses supporting equipment to effectively reduce the viscosity of the polyurethane resin; and due to the use of supercritical CO2 continuous viscosity reduction and continuous shear emulsification process, the pressure resistance requirements of the reaction equipment for continuous emulsification production are effectively reduced.

[0013] Furthermore, the CO2 is heated by a gas storage tank through a heat exchanger and pressurized by a second booster pump to maintain the temperature of CO2>32°C and the pressure of CO2>7.4MPa.

[0014] Furthermore, the temperature of the CO2 is 35-45°C, and the pressure of the CO2 is 7.5-8.5 MPa.

[0015] Furthermore, when the equipment is running, the pressure settings of the first booster pump and the third booster pump are synchronized with the second booster pump, for example, they are synchronously set to 7.5-8.5 MPa.

[0016] Furthermore, when the polyurethane prepolymer obtained in S1 passes through the first booster pump, the material temperature is maintained at 40-80° C.; By adjusting the second flow meter, the amount of supercritical CO2 is 5-50 wt% of the amount of the waterborne polyurethane resin, preferably 10-30 wt%; By adjusting the fourth flow meter, the mass ratio of the aqueous polyurethane resin to the water or the aqueous solution of the salt-forming agent is made to be aqueous polyurethane resin: water or the aqueous solution of the salt-forming agent = (30-50): (70-50); Alternatively, the stirring speed in S4 is 100-1000 rpm, and the stirring time is 0.5-1 h.

[0017] Furthermore, by adjusting the second flow meter, the amount of supercritical CO2 is set to 10-30 wt% of the amount of the aqueous polyurethane resin.

[0018] Furthermore, the method further includes S5: performing a chain extension reaction on the organic solvent-free emulsified aqueous polyurethane resin obtained in S4, comprising the following steps: The temperature of the post-chain extension device is lowered to 5-25°C, and the chain extender is then added dropwise. After the addition is completed, the temperature is maintained at 5-25°C and the reaction is continued for 1-3 hours to obtain an organic solvent-free emulsified chain-extended waterborne polyurethane resin.

[0019] The polyols used in the present invention include polytetramethylene ether, polypropylene glycol ether, polyadipic acid polyester, polycaprolactone, polycarbonate, and mixtures thereof; the isocyanates used include MDI, TDI, HDI, IPDI, HMDI, and mixtures thereof; the diol chain extenders used include ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.; the diamine chain extenders used include ethylenediamine, butanediamine, hexamethylenediamine, isophoronediamine, etc.; the catalyst used is an organic tin, preferably stannous octoate or dibutyltin dilaurate.

[0020] For nonionic waterborne polyurethane, the hydrophilic polyol used is polyethylene glycol, trimethylolpropane polyethylene glycol monomethyl ether, or a copolyether containing ethylene oxide (EO) segments.

[0021] For cationic waterborne polyurethane, the hydrophilic chain extenders used include diethanolamine, triethanolamine, N-methyldiethanolamine (MDEA), N-ethyldiethanolamine (N-EDEA), N-propyldiethanolamine (N-PDEA), N-benzyldiethanolamine (N-BDEA), tert-butyldiethanolamine (t-BuDEAt), dimethylethanolamine, bis(2-hydroxyethyl)benzylaniline (BHBA) and bis(2-hydroxypropyl)aniline (BHPA), among which N-methyldiethanolamine (MDEA) is preferred. The salt-forming agents used include formic acid, glycolic acid, acetic anhydride and glacial acetic acid.

[0022] For anionic waterborne polyurethane, the hydrophilic chain extender used includes dimethylol propionic acid (DMPA), dimethylol butyric acid (DMBA), 1,2-propanediol-3 sodium sulfonate, 1,4-butanediol-2-sodium sulfonate, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium (BES-Na), 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt (AAS-Na), and the salt forming agent used includes triethylamine, NaOH, KOH, Ba(OH)2, LiOH, Cs2CO3, K2CO3.

[0023] Compared with the prior art, the application has the following advantages: (1) The device for preparing waterborne polyurethane resin by continuous emulsification provided by the application realizes the continuous and automatic emulsion production process by organically integrating the pre-polymer synthesis, supercritical CO2 viscosity reduction, water dispersion, continuous emulsification and post chain extension process. The supercritical CO2 adding device can introduce supercritical CO2 as a green viscosity reducer into the pre-polymer, significantly reduce the system viscosity, and avoid the organic solvent residue and VOC emission pressure caused by the traditional acetone method. At the same time, the continuous emulsification device ensures efficient and stable dispersion of the pre-polymer and the water phase, uniform particle size distribution, and higher consistency between batches. The overall production process can reduce manual operation and energy consumption, improve production efficiency and large-scale capacity, and meet the industrial demand for green, environmentally friendly and efficient preparation of waterborne polyurethane resin.

[0024] (2) The production process provided by the application realizes online viscosity reduction by continuously introducing supercritical CO2 after the pre-polymer synthesis, does not need to use flammable organic solvents, significantly improves the safety and environmental protection level, and uniformly mixes the supercritical CO2 with the pre-polymer in a short time, which can quickly and controllably reduce the system viscosity to create ideal conditions for subsequent water dispersion and emulsification. The proportional feeding and continuous mixing emulsification are used in the process flow, which avoids the multiple feeding, batch operation and temperature fluctuation in the batch method, realizes the high automation and continuous stability of material conveying, proportional ratio and mixing emulsification, and greatly improves the production efficiency. Moreover, the online post chain extension step can complete the molecular structure regulation immediately after emulsification, ensuring the controllability and consistency of the emulsion structure and performance. The overall process is not only suitable for different systems such as nonionic, cationic and anionic, but also can flexibly adjust the formula parameters to meet the diversified application requirements, and has the comprehensive advantages of process simplification, energy consumption reduction, production scaling and product consistency.

[0025] (3) The equipment for preparing waterborne polyurethane resin by continuous emulsification of the present invention has a simple and compact structure and a rational design. The functional units are precisely connected, facilitating continuous and automated production. The modules have clear division of labor and efficient collaboration, making operation and maintenance easy. The overall system is easy to manufacture and install, and its capacity and specifications can be flexibly adjusted according to the production scale to meet different production capacity requirements. By integrating functional modules such as supercritical CO2 addition, water dispersion, continuous emulsification, and post-chain extension, intermediate transportation and manual intervention are reduced, and production safety, stability, and efficiency are improved. The system has good industrial application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the equipment for preparing waterborne polyurethane resin by continuous emulsification according to the present invention; In the figure: 1. Prepolymer synthesis device, 2. Supercritical CO2 addition device, 3. Water addition device, 4. Continuous emulsification device, 5. Post-chain extension device; 1-1, synthesis reactor tank, 1-2, synthesis reactor stirring paddle, 1-3, synthesis reactor heating device, 1-4, feeding port, 1-5, synthesis reactor pressure gauge, 1-6, synthesis reactor thermometer, 1-7, discharge port, 1-8, synthesis reactor valve; 2-1, first booster pump, 2-9, second booster pump, 2-2, first pressure gauge, 2-10, second pressure gauge, 2-3, first flow meter, 2-11, second flow meter, 2-4, first check valve, 2-12, second check valve, 2-5, gas storage tank, 2-6, gas valve, 2-7, heat exchanger, 2-8, first thermometer, 2-13, first proportional feeder, 2-14, static mixer; 3-1, third flow meter, 3-2, third one-way valve, 3-3, water tank, 3-4, water tank valve, 3-5, third booster pump, 3-6, third pressure gauge, 3-7, fourth flow meter, 3-8, fourth one-way valve, 3-9, second proportional feeder, 3-10, second thermometer; 4-1. Horizontal high-speed continuous emulsifier; 5-1. Chain extension reactor tank body, 5-2. Chain extension reactor stirring paddle, 5-3. Chain extension reactor heating device, 5-4. Feed port, 5-5. Chain extension reactor pressure gauge, 5-6. Chain extension reactor thermometer.

[0027] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] It should be noted that the terms "inward" and "outward" used in the following description refer to directions toward or away from the geometric center of a particular component, respectively. Furthermore, unless otherwise expressly specified or limited, the terms "connected," "connected," and "communicated" should be interpreted broadly, meaning, for example, directly connected, indirectly connected through an intermediary, or internally connected between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention.

[0030] like Figure 1 As shown, the present invention provides a production equipment for preparing waterborne polyurethane resin by continuous emulsification, which mainly includes: a prepolymer synthesis device 1, a supercritical carbon dioxide addition device 2, a water addition device 3, an emulsification device 4 and a post-chain extension device 5.

[0031] The prepolymer synthesis device 1 includes a hollow synthesis reactor vessel 1-1 equipped with a synthesis reactor stirring paddle 1-2 for uniformly mixing the raw materials. Synthesis reactor heating devices 1-3 are installed on both sides of the synthesis reactor vessel 1-1 to maintain the required reaction temperature. A feed port 1-4, a synthesis reactor pressure gauge 1-5, and a synthesis reactor thermometer 1-6 are located at the top of the vessel for feeding raw materials and monitoring the process. A discharge port 1-7 is located at the bottom of the vessel, connected to a downstream supercritical carbon dioxide addition device 2 via a synthesis reactor valve 1-8.

[0032] The supercritical CO2 addition device 2 primarily comprises a first booster pump 2-1, a first pressure gauge 2-2, a first flowmeter 2-3, a first one-way valve 2-4, a first proportional feeder 2-13, and a static mixer 2-14 connected in series. Furthermore, the device also comprises a gas storage tank 2-5, a gas valve 2-6, a heat exchanger 2-7, a first thermometer 2-8, a second booster pump 2-9, a second pressure gauge 2-10, a second flowmeter 2-11, and a second one-way valve 2-12. These components are also connected in series to form a supercritical CO2 gas supply system. The second one-way valve 2-12 is connected to the first proportional feeder 2-13 to uniformly mix a predetermined amount of supercritical CO2 into the prepolymer material.

[0033] The water adding device 3 comprises a water tank 3-3 and a water tank valve 3-4 for storing and adjusting water or a salt forming agent solution. The water or salt forming agent solution is delivered through a third booster pump 3-5 and a third pressure gauge 3-6, a fourth flow meter 3-7, a fourth one-way valve 3-8, a second proportional feeder 3-9, and a second thermometer 3-10, and the like in series to form a water or salt forming agent solution circuit, so as to realize quantitative water or salt forming agent solution adding and temperature control. Meanwhile, the third flow meter 3-1 is connected with the third one-way valve 3-2 in series, and the outlet of the third one-way valve 3-2 is connected with the second proportional feeder 3-9, so as to ensure the fluid flow direction and proportional control.

[0034] The emulsifying device 4 adopts a horizontal high-speed continuous emulsifying machine 4-1 for high-shear and high-speed homogenization and emulsification of the pre-polymer mixture after adding supercritical CO2 and water, so as to prepare a stable waterborne polyurethane emulsion.

[0035] The post-chain extension device 5 comprises a chain extension reaction kettle body 5-1 which is also a hollow structure and is internally provided with a chain extension reaction kettle stirring paddle 5-2 for realizing reprocessing or chain extension reaction of the material after emulsification. The kettle body is provided with a chain extension reaction kettle heating device 5-3 on both sides to maintain the temperature, and is provided with a material inlet 5-4, a chain extension reaction kettle pressure gauge 5-5, and a chain extension reaction kettle thermometer 5-6 on the top, so as to facilitate feeding and reaction process monitoring.

[0036] In terms of process connection, the pre-polymer synthesis device 1 is connected with the first booster pump 2-1 of the supercritical CO2 adding device 2 through a synthesis reaction kettle valve 1-8. After supercritical CO2 addition and mixing, the material is delivered to the inlet of the third flow meter 3-1 of the water adding device 3 through a static mixer 2-14. The mixture after treatment of the water adding device 3 further flows into the emulsifying device 4 for continuous emulsification, and finally enters the material inlet 5-4 of the post-chain extension device 5 through the outlet of the emulsifying device 4, so as to finally complete the preparation process of the waterborne polyurethane.

[0037] Example 1 The reaction temperature of the pre-polymer synthesis device 1 is set to 70℃, and the temperature of the pre-polymer reaction after flowing through the synthesis reaction kettle valve 1-8 is 45℃. The pressures of the first booster pump 2-1 and the second booster pump 2-9 of the supercritical CO2 adding device 2 are both set to 7.6MPa; the heat exchanger 2-7 is set to heat the CO2 temperature to 42℃; the flow rate of the first flow meter 2-3 is set to 1.0kg / min, and the flow rate of the second flow meter 2-11 is set to 0.15kg / min. The water tank 3-3 stores a water solution with a triethylamine mass content of 0.78%, the flow rate of the third flow meter 3-1 of the water adding device 3 is calibrated to 1.15kg / min, and the flow rate of the fourth flow meter 3-7 is set to 1.5kg / min.

[0038] The following raw materials were added to prepolymer synthesis unit 1: 100 kg of polycaprolactone (PCL2000) with a molecular weight of 2000 g / mol, 4.2 kg of dimethylolpropionic acid (DMPA), 12.23 kg of toluene diisocyanate (TDI), and 0.07 kg of stannous octoate. The reaction temperature was set at 70°C and the reaction was allowed to proceed for 3.5 hours. 0.25 kg of 1,4-butanediol was then added dropwise and the reaction continued for 1 hour. The temperature was lowered to 55°C, and valves 1-8 of the synthesis reactor were opened. The supercritical CO2 addition unit 2, water addition unit 3, and continuous emulsification unit 4 were started according to the above settings. Simultaneously, the chain extension reactor agitator 5-2 of the post-chain extension unit 5 was started and the speed was set to 200 rpm. After all the materials had flowed through the entire unit and reached the post-chain extension unit 5, stirring was continued at room temperature for 1 hour to produce an anionic waterborne polyurethane resin with a solids content of 40%.

[0039] Example 2 The reaction temperature of the prepolymer synthesis unit 1 was set at 75°C, and the temperature of the fluid flowing through valve 1-8 of the synthesis reactor after the prepolymer reaction was completed was set at 65°C. The pressures of the first booster pump 2-1 and the second booster pump 2-9 of the supercritical CO2 addition unit 2 were both set at 7.8 MPa. A heat exchanger 2-7 was installed to heat the CO2 to 44°C. The flow rates of the first flowmeter 2-3 and the second flowmeter 2-11 were set at 1.0 kg / min and 0.12 kg / min, respectively. Deionized water was stored in the water tank 3-3, and the flow rate of the third flowmeter 3-1 was calibrated to 1.12 kg / min. The flow rate of the fourth flowmeter 3-7 was set at 1.38 kg / min.

[0040] The following raw materials were added to prepolymer synthesis unit 1: 240 kg of polytetramethylene glycol (PTMEG 2000) with a molecular weight of 2000 g / mol, 32 kg of polyethylene glycol with a molecular weight of 500 g / mol, 40 kg of trimethylolpropane polyethylene glycol monomethyl ether (mPEG) with a molecular weight of 420 g / mol, 2 kg of 1,4-butanediol (BDO), 0.1 kg of dibutyltin dilaurate, 40 kg of isophorone diisocyanate (IPDI), and 80 kg of 4,4-diisocyanatodicyclohexylmethane (HMDI). The reaction was allowed to proceed at 75°C under nitrogen for 4.5 hours. The temperature of the materials was lowered to 50°C, and valves 1-8 of the synthesis reactor were opened. The supercritical CO2 addition unit 2, water addition unit 3, and continuous emulsification unit 4 were started according to the above settings. Simultaneously, the chain extension reactor agitator 5-2 of the post-chain extension unit 5 was started and the speed of the agitator 5-2 was set to 800 rpm. After all the materials have flowed through the complete set of equipment to the post-chain extension device 5, stirring is continued for 0.5 hours to obtain a non-ionic waterborne polyurethane resin with a solid content of 42%.

[0041] Example 3 The reaction temperature of the prepolymer synthesis unit 1 was set at 80°C, and the temperature of the liquid flowing through valve 1-8 of the synthesis reactor after the prepolymer reaction was completed was set at 72°C. The pressures of the first booster pump 2-1 and the second booster pump 2-9 of the supercritical CO2 addition unit 2 were both set at 8.0 MPa. A heat exchanger 2-7 was installed to heat the CO2 to 42°C. The flow rates of the first flowmeter 2-3 and the second flowmeter 2-11 were set at 1.0 kg / min and 0.2 kg / min, respectively. A water tank 3-3 was filled with an aqueous solution containing 0.46% acetic acid. The flow rates of the third flowmeter 3-1 and the fourth flowmeter 3-7 of the water addition unit 3 were calibrated to 1.20 kg / min and 1.5 kg / min, respectively.

[0042] The raw materials were added according to the following design: 100 kg of polyneopentyl adipate (PNA2000) with a molecular weight of 2000 g / mol, 3.8 kg of N-methyldiethanolamine (MDEA), 0.25 kg of 1,4-butanediol (BDO), 0.07 kg of stannous octoate, 6.1 kg of toluene diisocyanate (TDI), and 5.9 kg of hexamethylene diisocyanate (HDI). The raw materials were added into the prepolymer synthesis device 1, and the mixture was reacted at 80° C. for 3.5 hours under nitrogen protection. The material temperature was lowered to 56° C., and valves 1-8 of the synthesis reactor were opened. The supercritical CO2 addition device 2, the water addition device 3, and the continuous emulsification device 4 were started according to the above settings. At the same time, the chain extension reactor stirring paddle 5-2 of the post-chain extension device 5 was started, and the speed of the chain extension reactor stirring paddle 5-2 was set to 500 rpm. After all the materials have flowed through the complete set of equipment to the post-chain extension device 5, stirring is continued for 0.5 hours to obtain a cationic waterborne polyurethane resin with a solid content of 40%.

[0043] Example 4 The reaction temperature of the prepolymer synthesis unit 1 was set at 70°C, and the temperature of the liquid flowing through valve 1-8 of the synthesis reactor after the prepolymer reaction was completed was set at 42°C. The pressures of the first booster pump 2-1 and the second booster pump 2-9 of the supercritical CO2 addition unit 2 were both set at 7.6 MPa. A heat exchanger 2-7 was installed to heat the CO2 to 42°C. The flow rate of the first flowmeter 2-3 was set at 1.0 kg / min, and the flow rate of the second flowmeter 2-11 was set at 0.35 kg / min. A water tank 3-3 was filled with an aqueous solution containing 0.46% KOH. The flow rate of the third flowmeter 3-1 was calibrated to 1.35 kg / min, and the flow rate of the fourth flowmeter 3-7 was set to 1.5 kg / min.

[0044] The raw materials were put in according to the following design: 160 kg of polycarbonate diol (PCD) with a molecular weight of 2000 g / mol, 8.9 kg of dimethylol propionic acid (DMPA), 45.6 kg of isophorone diisocyanate (IPDI), 0.11 kg of stannous octoate, into the prepolymer synthesis device 1, under nitrogen protection, reacted at 70°C for 3.5 h, the material temperature was reduced to 45°C, the synthesis reactor valve 1-8 was opened, the supercritical CO2 addition device 2, water addition device 3 and continuous emulsification device 4 were opened according to the above setting, and the chain extension reactor stirring paddle 5-2 of the post-chain extension device 5 was opened, and the chain extension reactor stirring paddle 5-2 was set to 420 rpm. After the material flowed through the complete set of devices to the post-chain extension device 5, the material was cooled to 10°C after stirring for 0.5 h, 1.2 kg of ethylenediamine was added, the stirring paddle speed was maintained at 420 rpm, and the reaction was continued for 1.5 h, to obtain an anionic waterborne polyurethane resin with a solid content of 40%.

[0045] Example 5 The reaction temperature of the prepolymer synthesis device 1 was set to 80°C, and the temperature of the prepolymer reaction flowing through the synthesis reactor valve 1-8 was 42°C after the reaction was completed. The first booster pump 2-1 and the second booster pump 2-9 of the supercritical CO2 addition device 2 were both set to 8.2 MPa; the CO2 temperature was heated to 42°C by setting the heat exchanger 2-7; the first flow meter 2-3 was set to 1.0 kg / min, and the second flow meter 2-11 was set to 0.25 kg / min. Deionized water was stored in the water tank 3-3, the third flow meter 3-1 was calibrated to 1.25 kg / min, and the fourth flow meter 3-7 was set to 1.22 kg / min.

[0046] The raw materials were put in according to the following design: 160 kg of polycarbonate diol (PCD) with a molecular weight of 2000 g / mol, 8.9 kg of dimethylol propionic acid (DMPA), 45.6 kg of isophorone diisocyanate (IPDI), 0.11 kg of stannous octoate, into the prepolymer synthesis device 1, under nitrogen protection, reacted at 70°C for 3.5 h, the material temperature was reduced to 45°C, the synthesis reactor valve 1-8 was opened, the supercritical CO2 addition device 2, water addition device 3 and continuous emulsification device 4 were opened according to the above setting, and the chain extension reactor stirring paddle 5-2 of the post-chain extension device 5 was opened, and the chain extension reactor stirring paddle 5-2 was set to 420 rpm. After the material flowed through the complete set of devices to the post-chain extension device 5, the material was cooled to 10°C after stirring for 0.5 h, 1.2 kg of ethylenediamine was added, the stirring paddle speed was maintained at 420 rpm, and the reaction was continued for 1.5 h, to obtain an anionic waterborne polyurethane resin with a solid content of 40%.

[0047] The particle size of the prepared waterborne polyurethane resin was tested using a laser particle size analyzer. The emulsion stability was tested using a high-speed centrifuge at 10,000 rpm for 30 minutes. The state of the emulsion in the centrifuge tube was observed. The results are as follows: Table 1

[0048] In summary, the present invention adopts a complete set of equipment with a compact structure, reasonable design and easy manufacturing, and combines supercritical CO2 continuous viscosity reduction and continuous shear emulsification process to efficiently integrate key steps such as prepolymer synthesis, supercritical CO2 viscosity reduction, water dispersion, continuous emulsification and post-chain extension into one, thereby constructing a complete continuous preparation process. The continuous emulsification device ensures efficient and stable dispersion of the prepolymer and the aqueous phase, uniform particle size distribution, and higher consistency between product batches. This process not only achieves online viscosity reduction, precise proportion feeding and efficient and stable emulsification of polyurethane prepolymers, but also significantly reduces the requirements of the emulsification process on the pressure resistance of the equipment, simplifies the system design, and at the same time, greatly improves production efficiency and consistency between product batches. It is suitable for the green, environmentally friendly and large-scale preparation of various types of water-based polyurethanes and has good industrial promotion value.

[0049] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A device for preparing waterborne polyurethane resin by continuous emulsification, comprising a prepolymer synthesis device (1), a water adding device (3), an emulsifying device (4), and a post-chain extension device (5), characterized in that: It also includes a supercritical CO2 addition device (2); The supercritical CO2 addition device (2) comprises a first booster pump (2-1), a second booster pump (2-9), a first pressure gauge (2-2), a second pressure gauge (2-10), a first flow meter (2-3), a second flow meter (2-11), a first one-way valve (2-4), a second one-way valve (2-12), a gas storage tank (2-5), a gas valve (2-6), a heat exchanger (2-7), a first thermometer (2-8), a first proportional feeder (2-13), and a static mixer (2-14); wherein, the first booster pump (2 -1), a first pressure gauge (2-2), a first flow meter (2-3), a first one-way valve (2-4), a first proportional feeder (2-13) and a static mixer (2-14) are connected in series; the gas storage tank (2-5), the gas valve (2-6), the heat exchanger (2-7), the first thermometer (2-8), the second booster pump (2-9), the second pressure gauge (2-10), the second flow meter (2-11) and the second one-way valve (2-12) are connected in series; the second one-way valve (2-12) is connected to the first proportional feeder (2-13); The water adding device (3) comprises a third flow meter (3-1), a third one-way valve (3-2), a water tank (3-3), a water tank valve (3-4), a third booster pump (3-5), a third pressure gauge (3-6), a fourth flow meter (3-7), a fourth one-way valve (3-8), a second proportional feeder (3-9), and a second thermometer (3-10); wherein the water tank (3-3), the water tank valve (3-4), the third booster pump (3-5), the third pressure gauge (3-6), the fourth flow meter (3-7), the fourth one-way valve (3-8), the second proportional feeder (3-9), and the second thermometer (3-10) are connected in series, the third flow meter (3-1) is connected in series with the third one-way valve (3-2), and the third one-way valve (3-2) is connected to the second proportional feeder (3-9); The prepolymer synthesis device (1) is connected to the first booster pump (2-1) of the supercritical CO2 addition device (2), the static mixer (2-14) of the supercritical CO2 addition device (2) is connected to the third flow meter (3-1) of the water addition device (3), the water addition device (3) is connected to the emulsification device (4), and the emulsification device (4) is connected to the post-chain extension device (5).

2. The equipment for preparing waterborne polyurethane resin by continuous emulsification according to claim 1, characterized in that: The prepolymer synthesis device (1) is a normal pressure reactor; the emulsification device (4) is a horizontal high-speed continuous emulsifier; and the post-chain extension device (5) is a normal pressure reactor.

3. The equipment for preparing waterborne polyurethane resin by continuous emulsification according to claim 1, characterized in that: The prepolymer synthesis device (1) comprises a synthesis reactor tank body (1-1), a synthesis reactor stirring paddle (1-2), a synthesis reactor heating device (1-3), a feeding port (1-4), a synthesis reactor pressure gauge (1-5), a synthesis reactor thermometer (1-6), a discharge port (1-7), and a synthesis reactor valve (1-8); the synthesis reactor tank body (1-1) is a hollow structure, and a synthesis reactor stirring paddle (1-2) is arranged inside the synthesis reactor tank body; the feeding port (1-4), the synthesis reactor pressure gauge (1-5), and the synthesis reactor thermometer (1-6) are respectively arranged on the top of the synthesis reactor tank body (1-1); the synthesis reactor heating device (1-3) is arranged on both sides of the synthesis reactor tank body (1-1); the discharge port (1-7) is located at the bottom of the synthesis reactor tank body (1-1) and is connected to the synthesis reactor valve (1-8); The post-chain extension device (5) comprises a chain extension reactor tank body (5-1), a chain extension reactor stirring paddle (5-2), a chain extension reactor heating device (5-3), a feed port (5-4), a chain extension reactor pressure gauge (5-5), and a chain extension reactor thermometer (5-6); wherein the chain extension reactor tank body (5-1) is a hollow structure, and a chain extension reactor stirring paddle (5-2) is arranged inside the chain extension reactor tank body; the chain extension reactor heating device (5-3) is arranged on both sides of the chain extension reactor tank body (5-1); and the feed port (5-4), the chain extension reactor pressure gauge (5-5), and the chain extension reactor thermometer (5-6) are respectively arranged on the top of the chain extension reactor tank body (5-1).

4. A production process for preparing waterborne polyurethane resin by continuous emulsification, characterized in that: The production process is carried out using the equipment for preparing waterborne polyurethane resin by continuous emulsification as described in any one of claims 1 to 3, comprising the following steps: S1: completing the synthesis of polyurethane prepolymer in the prepolymer synthesis device (1); S2: The supercritical CO2 generating device (2) is turned on, and the polyurethane prepolymer obtained in S1 is pressurized by a first booster pump (2-1) and then transported to a first proportional feeder (2-13); CO2 is heated by a gas storage tank (2-5) through a heat exchanger (2-7), and pressurized by a second booster pump (2-9), and then transported to the first proportional feeder (2-13) while maintaining a supercritical state; then, the polyurethane prepolymer and supercritical CO2 are simultaneously transported from the first proportional feeder (2-13) to a static mixer (2-14), thereby obtaining a polyurethane prepolymer with viscosity reduced by supercritical CO2; S3: The water adding device (3) is turned on to convey the polyurethane prepolymer subjected to supercritical CO2 viscosity reduction from the static mixer (2-14) to the second proportional feeder (3-9) of the water adding device (3); the water or the aqueous solution of the salt-forming agent in the water tank (3-3) is pressurized by the third booster pump (3-5) and conveyed to the second proportional feeder (3-9), and then conveyed to the emulsifying device (4) through the second proportional feeder (3-9) together with the polyurethane prepolymer subjected to supercritical CO2 viscosity reduction, and then emulsified in the emulsifying device (4) to obtain a continuously emulsified waterborne polyurethane resin; S4: starting the post-chain extension device (5), and then conveying the continuously emulsified waterborne polyurethane resin obtained in S3 to the post-chain extension device (5) for stirring to obtain an organic solvent-free emulsified waterborne polyurethane resin; The production process is suitable for the preparation of nonionic, cationic and anionic waterborne polyurethanes.

5. The production process for preparing waterborne polyurethane resin by continuous emulsification according to claim 4, characterized in that: The CO2 is heated by the gas storage tank (2-5) through the heat exchanger (2-7) and pressurized by the second booster pump (2-9), maintaining the temperature of CO2>32°C and the pressure of CO2>7.4MPa.

6. The production process for preparing waterborne polyurethane resin by continuous emulsification according to claim 5, characterized in that: The temperature of the CO 2 is 35-45° C., and the pressure of the CO 2 is 7.5-8.5 MPa.

7. The production process for preparing waterborne polyurethane resin by continuous emulsification according to claim 4, characterized in that: When the equipment is running, the pressure settings of the first booster pump (2-1) and the third booster pump (3-5) are synchronized with the second booster pump (2-9).

8. The process for preparing waterborne polyurethane resin by continuous emulsification according to claim 4, characterized in that: When the polyurethane prepolymer obtained by S1 passes through the first booster pump (2-1), the material temperature is maintained at 40-80°C; By adjusting the second flow meter (2-11), the amount of supercritical CO2 is 5-50 wt% of the amount of the waterborne polyurethane resin; By adjusting the fourth flow meter (3-7), the mass ratio of the aqueous polyurethane resin to the water or the aqueous solution of the salt-forming agent is made to be aqueous polyurethane resin: water or the aqueous solution of the salt-forming agent = (30-50): (70-50); Alternatively, the stirring speed in S4 is 100-1000 rpm, and the stirring time is 0.5-1 h.

9. The process for preparing waterborne polyurethane resin by continuous emulsification according to claim 8, characterized in that: By adjusting the second flow meter (2-11), the amount of supercritical CO2 is set to 10-30 wt% of the amount of the waterborne polyurethane resin.

10. The production process for preparing waterborne polyurethane resin by continuous emulsification according to claim 4, characterized in that: The method further includes S5: performing a chain extension reaction on the organic solvent-free emulsified waterborne polyurethane resin obtained in S4, including the following steps: The temperature of the post-chain extension device (5) is lowered to 5-25°C, and the chain extender is then added dropwise. After the addition is completed, the temperature is maintained at 5-25°C and the reaction is continued for 1-3 hours to obtain an organic solvent-free emulsified chain-extended waterborne polyurethane resin.

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